Upfront vs. no upfront neck dissection in primary head and neck cancer radio(chemo)therapy: Reply to Elicin et al.

Publication date: Available online 4 January 2018
Source:Radiotherapy and Oncology
Author(s): Daan Nevens, Fréderic Duprez, Katrien Bonte, Philippe Deron, Wouter Huvenne, Annouschka Laenen, Wilfried De Neve, Sandra Nuyts




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A young girl with severe cerebral fungal infection due to card 9 deficiency

Publication date: Available online 4 January 2018
Source:Clinical Immunology
Author(s): Pinar Gur Cetinkaya, Deniz Cagdas Ayvaz, Betül Karaatmaca, Rahsan Gocmen, Figen Söylemezoğlu, Wayne Bainter, Janet Chou, Talal A. Chatila, Ilhan Tezcan
Pattern recognition receptors (PRRs), receptors of the innate immune system, are important in interaction with pathogens. Caspase Recruitment Domain-containing protein 9 (CARD9), a member of PRRs, is an intracellular adaptor protein important in fungal defense. CARD9 deficiency causes a rare primary immunodeficiency (PID) characterized by superficial and deep fungal infections. We report a 17year-old female with a homozygous nonsense mutation in CARD9, who presented with severe cerebral fungal infection of the central nervous system. She was also found to have an heterozygous NLRP12 mutation, which may have had add-on effect on the severity of the infection.



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Light attenuation versus evolved carbon (AVEC) – A new way to look at elemental and organic carbon analysis

Publication date: February 2018
Source:Atmospheric Environment, Volume 175
Author(s): E.M.G. Nicolosi, P. Quincey, A. Font, G.W. Fuller
The Attenuation Versus Evolved Carbon (AVEC) plot is a new way to represent thermal-optical organic carbon/elemental carbon (OC/EC) analysis data. The accumulated carbon concentration is plotted against the attenuation (ln (I0/I)). Unlike the thermogram, it provides information about the sample properties rather than the instantaneous instrument sensor status.The plot can be used to refine the determination of OC and EC split point, either from consideration of laser instability or transit time within the instrument; to investigate the optical properties of the particles; and to spot the early evolution of pyrolysed carbon (PC) and/or EC during the inert phase.168 samples from three sites were studied. The gradient of the AVEC plot curve in the oxygenated phase provides information about the mass absorption cross section (σ) of the particles leaving the filter. The σ of the PC generated in the higher temperature Quartz protocol was greater than the PC generated in the lower temperature EUSAAR_2 protocol. Also, in both cases the PC evolved at a lower temperature in the oxygenated phase than the native EC.To minimise the shadowing effect, σ was also measured for the particles leaving the filter at the end of the analysis. These σ values, which are expected to be a combination of inherent σ together with fixed instrumental factors, were consistent between the different sites (45 ± 10 m² g⁻¹ in rural samples, 42 ± 8 m² g⁻¹ in urban samples and 35 ± 14 m² g⁻¹ in roadside samples).The AVEC plot can be generated from the data routinely produced by the analytical instrument using the R-code supplied in the supplementary material.

Graphical abstract

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Ozone impact minimization through coordinated scheduling of turnaround operations from multiple olefin plants in an ozone nonattainment area

Publication date: March 2018
Source:Atmospheric Environment, Volume 176
Author(s): Sijie Ge, Sujing Wang, Qiang Xu, Thomas Ho
Turnaround operations (start-up and shutdown) are critical operations in olefin plants, which emit large quantities of VOCs, NOx and CO. The emission has great potentials to impact the ozone level in ozone nonattainment areas. This study demonstrates a novel practice to minimize the ozone impact through coordinated scheduling of turnaround operations from multiple olefin plants located in Houston, Texas, an ozone nonattainment area. The study considered two olefin plants scheduled to conduct turnaround operations: one start-up and one shutdown, simultaneously on the same day within a five-hour window. Through dynamic simulations of the turnaround operations using ASPEN Plus Dynamics and air quality simulations using CAMx, the study predicts the ozone impact from the combined effect of the two turnaround operations under different starting-time scenarios. The simulations predict that the ozone impact from planned turnaround operations ranges from a maximum of 11.4 ppb to a minimum of 1.4 ppb. Hence, a reduction of up to 10.0 ppb can be achieved on a single day based on the selected two simulation days. This study demonstrates a cost-effective and environmentally benign ozone control practice for relevant stakeholders, including environmental agencies, regional plant operators, and local communities.

Graphical abstract

http://ift.tt/2lVzicY

Emission factors of greenhouse gases from layer and broiler barns in Cameroon

Publication date: March 2018
Source:Atmospheric Environment, Volume 176
Author(s): N. Martin Ngwabie, Ada N. Acobta, Veronica E. Manga, Andrew C. VanderZaag
Limited information is available in the literature on greenhouse gas (GHG) quantification from livestock production systems in Africa. Therefore, this project was carried out to generate baseline emission factors of methane (CH4), nitrous oxide (N2O) and carbon dioxide (CO2) from broiler and layer barns with building design typical of Cameroon. Emissions were measured from two broiler barns during the entire production cycles and a layer barn for a limited period using flux chambers. Methane emission factors from the broiler barns with mud and cement floors were 0.96 ± 1.04 and 0.36 ± 0.17 mg bird⁻¹ hr⁻¹ respectively, and 0.76 ± 0.56 mg bird⁻¹ hr⁻¹ from the layer barn with cement floor. Nitrous oxide emission from the broiler barns with mud and cement floors were 12.94 ± 10.11 and 1.68 ± 1.02 mg bird⁻¹ hr⁻¹ respectively, and 0.21 ± 0.28 mg bird⁻¹ hr⁻¹ from the layer barn. Carbon dioxide emission factors from the broiler barns with mud and cement floors were 9327 ± 3508 and 25526 ± 6904 mg bird⁻¹ hr⁻¹ respectively, and 8942 ± 36756 mg bird⁻¹ hr⁻¹ from the layer barn. When scaled per livestock unit (LU), where 1 LU is 500 kg bird weight, CH4 emissions were 0.16 ± 0.17 and 0.06 ± 0.03 g LU⁻¹ hr⁻¹ from the broiler barns, and 0.19 ± 0.14 g LU⁻¹ hr⁻¹ from the layer barn. Nitrous oxide emissions were 2.16 ± 1.69 and 0.28 ± 0.17 g LU⁻¹ hr⁻¹ from the broiler barns, and 0.05 ± 0.07 g LU⁻¹ hr⁻¹ from the layer barn. Broilers reared in management systems with wood shavings on mud floor had relatively high CH4 and N2O emissions compared to broilers on wood shavings and cement floor, with the contrary observed for CO2. The emissions N2O were significantly higher from broiler barns compared to layer barns. Emissions were higher in the mornings compared to later periods of the day. Given the observed results, GHG emission mitigation strategies need to be customised for each building design and management system.



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Contribution of microenvironments to personal exposures to PM10 and PM2.5 in summer and winter

Publication date: February 2018
Source:Atmospheric Environment, Volume 175
Author(s): Yunhyung Hwang, Kiyoung Lee
Personal exposure to particulate matter (PM) can be affected by time–activity patterns and microenvironmental concentrations. Particle size is closely associated with potential health problems, where smaller particles have greater effects on health. We investigated the effects of time–activity patterns on personal exposure and the contribution of the microenvironment to personal exposure to PM with maximal diameters of 10 μm and 2.5 μm (PM10 and PM2.5, respectively) in summer and winter. Technicians carried a nephelometer to detect various sizes of PM while engaging in one of nine scripted time–location–activity patterns. The scripted activities were based on the time–activity patterns of nine groups of inhabitants of Seoul, Korea. The monitoring was repeated in summer and winter to assess seasonal variation. The differences of personal exposures to PM10 and PM2.5 in summer and winter were not significant. The greatest PM concentrations occurred in restaurants. The PM2.5/PM10 ratios were varied from 0.35 at schools to 0.92 at stores. In both seasons, the residential indoor microenvironment was the largest contributor to personal PM exposure. The other major contributors were restaurants, offices, schools, buses, and walking, although their contributions differed by season and particle size. The different microenvironmental contributions among the activity pattern groups suggest that personal exposure significantly differs according to activity pattern.



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Assessment of trace metal levels in size-resolved particulate matter in the area of Leipzig

Publication date: March 2018
Source:Atmospheric Environment, Volume 176
Author(s): Khanneh Wadinga Fomba, Dominik van Pinxteren, Konrad Müller, Gerald Spindler, Hartmut Herrmann
Size-resolved trace metal concentrations at four sites in Leipzig (Germany) and its surrounding were assessed between the winter of 2013 and the summer of 2015. The measurements were performed in parallel at; traffic dominated (Leipzig – Mitte, LMI), traffic and residential dominated (Eisenbahnstrasse, EIB), urban background (TROPOS, TRO) and regional background (Melpitz, MEL) sites. In total, 19 trace metals, i.e. K, Ca, Ti, Mn, Fe, Cu, Zn, As, Se, Ba, V, Pb, Ni, Cr, Sr, Sn, Sb, Co and Rb were analysed using total reflection x-ray fluorescence (TXRF). The major metals were Fe, K and Ca with concentrations ranging between; 31–440 ng/m³, 42–153 ng/m³ and 24–322 ng/m³, respectively, while the trace metals with the lowest concentrations were Co, Rb and Se with concentrations of; < 0.3 ng/m³, <0.5 ng/m³ and 0.5–0.7 ng/m³, respectively. PM10 trace metal concentrations during easterly air mass inflow especially at the background sites were in average 70% higher in the winter and 30% higher in the summer in comparison to westerly air mass inflow.Traffic at LMI contributed to about 75% of Cr, Ba, Cu, Sb, Sn, Ca, Co, Mn, Fe and Ti concentrations while regional activities contributed to more than 70% of K, Rb, Pb, Se, As and V concentrations. Traffic dominated trace metals were often observed in the coarse mode while the regional background dominated trace metals were often observed in the fine mode. Trace metal sources were related to crustal matter and road dust re-suspension for metals such as Ca, Fe, Co, Sr, and Ti, brake and tire wear (Cu, Sb, Ba, Fe, Zn, Pb), biomass burning (K, Rb), oil and coal combustion (V, Zn, As, Pb). Crustal matter contributed 5–12% in winter and 8–19% in summer of the PM10 mass. Using Cu and Zn as markers for brake and tire wear, respectively, the estimated brake and tire wear contributions to the PM10 mass were 0.1–0.8% and 1.7–2.9%, respectively. The higher contributions were observed at the traffic sites while the lower contributions were observed at the regional background site. In total, non-exhaust emissions could account for about 10–22% of the PM10 mass in the summer and about 7–15% of the PM10 mass in the winter.



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Biogenic volatile organic compound emissions from senescent maize leaves and a comparison with other leaf developmental stages

Publication date: March 2018
Source:Atmospheric Environment, Volume 176
Author(s): A. Mozaffar, N. Schoon, A. Bachy, A. Digrado, B. Heinesch, M. Aubinet, M.-L. Fauconnier, P. Delaplace, P. du Jardin, C. Amelynck
Plants are the major source of Biogenic Volatile Organic Compounds (BVOCs) which have a large influence on atmospheric chemistry and the climate system. Therefore, understanding of BVOC emissions from all abundant plant species at all developmental stages is very important. Nevertheless, investigations on BVOC emissions from even the most widespread agricultural crop species are rare and mainly confined to the healthy green leaves. Senescent leaves of grain crop species could be an important source of BVOCs as almost all the leaves senesce on the field before being harvested. For these reasons, BVOC emission measurements have been performed on maize (Zea mays L.), one of the most cultivated crop species in the world, at all the leaf developmental stages. The measurements were performed in controlled environmental conditions using dynamic enclosures and proton transfer reaction mass spectrometry (PTR-MS). The main compounds emitted by senescent maize leaves were methanol (31% of the total cumulative BVOC emission on a mass of compound basis) and acetic acid (30%), followed by acetaldehyde (11%), hexenals (9%) and m/z 59 compounds (acetone/propanal) (7%). Important differences were observed in the temporal emission profiles of the compounds, and both yellow leaves during chlorosis and dry brown leaves after chlorosis were identified as important senescence-related BVOC sources. Total cumulative BVOC emissions from senescent maize leaves were found to be among the highest for senescent Poaceae plant species. BVOC emission rates varied strongly among the different leaf developmental stages, and senescent leaves showed a larger diversity of emitted compounds than leaves at earlier stages. Methanol was the compound with the highest emissions for all the leaf developmental stages and the contribution from the young-growing, mature, and senescent stages to the total methanol emission by a typical maize leaf was 61, 13, and 26%, respectively. This study shows that BVOC emissions from senescent maize leaves cannot be neglected and further investigations in field conditions are recommended to further constrain the BVOC emissions from this important C4 crop species.

Graphical abstract

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Comparison of two different dust emission mechanisms over the Horqin Sandy Land area: Aerosols contribution and size distributions

Publication date: March 2018
Source:Atmospheric Environment, Volume 176
Author(s): Tingting Ju, Xiaolan Li, Hongsheng Zhang, Xuhui Cai, Yu Song
Dust aerosols (PM10) emission fluxes due to convective turbulent dust emissions (CTDE) and saltation-bombardment and/or aggregation-disintegration dust emissions (SADE) events were comparatively studied using the data obtained from the Naiman station over the Horqin Sandy Land area in Inner Mongolia, China from 2011 to 2015. The annual cumulative dust fluxes released by CTDE events was about one third of that by SADE events, with the order of 10³∼10⁴ μg m⁻² s⁻¹. The particle size distributions (PSDs) with diameter between 0.1 and 20 μm during CTDE and SADE events over the Horqin Sandy Land area were simulated based on the fragmentation theory, respectively. The results indicated that an improved equation based on fragmentation theory could be applied to describe the PSDs over the Horqin site which may be because the scale-invariant fragmentation theory mainly explains the PSDs of free dust particles on the surface, which differ from the PSDs of suspend airborne dust and the improved equation was more applicable to the PSDs of SADE events because the dust emission mechanism of SADE are saltation bombardment and aggregation disintegration. The number-related mean aerosol diameters (DN) barely varied under different friction velocity (u*) for SADE events, while the volume-related mean aerosol diameters (DV) changed distinctly with the change of u*. For CTDE events, the DN and DV had no obvious relationship with the change of u* because the dominating influence factor during CTDE event was thermal convection rather than u*. The mass-related PSDs usually exhibited a peak between 0.45 and 0.70 μm during SADE events, while for CTDE events there was a wide peak in the range of 0.10~0.70μm. The results suggest that DN should be not be recommended as an individual parameter to describe the PSDs. The mass-related PSDs can effectively distinguish the SADE and CTDE events.



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Atmospheric depositions of natural and anthropogenic trace elements on the Guliya ice cap (northwestern Tibetan Plateau) during the last 340 years

Publication date: March 2018
Source:Atmospheric Environment, Volume 176
Author(s): M. Roxana Sierra-Hernández, Paolo Gabrielli, Emilie Beaudon, Anna Wegner, Lonnie G. Thompson
A continuous record of 29 trace elements (TEs) has been constructed between 1650 and 1991 CE (Common Era) from an ice core retrieved in 1992 from the Guliya ice cap, on the northwestern Tibetan Plateau. Enrichments of Pb, Cd, Zn and Sb were detected during the second half of the 19th century and the first half of the 20th century (∼1850–1950) while enrichments of Sn (1965–1991), Cd and Pb (1975–1991) were detected during the second half of the 20th century. The EFs increased significantly by 20% for Cd and Sb, and by 10% for Pb and Zn during 1850–1950 relative to the pre-1850s. Comparisons of the Guliya TEs data with other ice core-derived and production/consumption data suggest that Northern Hemisphere coal combustion (primarily in Western Europe) is the likely source of Pb, Cd, Zn, and Sb during the 1850–1950 period. Coal combustion in Europe declined as oil replaced coal as the primary energy source. The European shift from coal to oil may have contributed to the observed Sn enrichment in ∼1965 (60% EF increase in 1975–1991), although regional fossil fuel combustion (coal and leaded gasoline) from western China, Central Asia, and South Asia (India, Nepal), as well as Sn mining/smelting in Central Asia, may also be possible sources. The post-1975 Cd and Pb enrichments (40% and 20% EF increase respectively in 1975–1991) may reflect emissions from phosphate fertilizers, fossil fuel combustion, and/or non-ferrous metal production, from western China, Central Asia, and/or South Asia. Leaded gasoline is likely to have also contributed to the post-1975 Pb enrichment observed in this record. The results strongly suggest that the Guliya ice cap has recorded long-distance emissions from coal combustion since the 1850s with more recent contributions from regional agriculture, mining, and/or fossil fuel combustion. This new Guliya ice core record of TEs fills a geographical gap in the reconstruction of the pollution history of this region that extends well beyond modern instrumental records.

Graphical abstract

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Oxidative potential of ambient fine aerosol over a semi-urban site in the Indo-Gangetic Plain

Publication date: February 2018
Source:Atmospheric Environment, Volume 175
Author(s): Anil Patel, Neeraj Rastogi
Indo-Gangetic Plain (IGP) receives emissions from variety of pollutant sources such as post-harvest crop residue burning, vehicles, industries, power plants, and bio-fuel burning. Several studies have documented physical, chemical and optical properties of aerosol over the IGP; however, their oxidative potential (OP) has not yet documented. Present study reports the OP (measured through dithiothreitol (DTT) assay) of soluble particulate matter smaller than 2.5 μm aerodynamic diameter (PM2.5) over Patiala (30.3°N, 76.4°E, 249 m amsl), a semi-urban site located in the IGP, during winter 2014. Volume-normalized OP (range: 1.3–7.2 nmol DTT min⁻¹ m⁻³, average: 3.8 ± 1.4, 1σ) is found to be ∼3 to 20 times higher, and mass-normalized OP (range: 13-50 pmol DTT min⁻¹ μg⁻¹, average: 27 ± 8, 1σ) is found to be similar or higher than those documented in literature. Further, observed OP is found to depend more on PM2.5 composition rather than mass concentration. Mass fractions of organic carbon (OC), elemental carbon (EC) and water-soluble organic carbon (WSOC) correlate positively whereas that of secondary inorganic aerosol (SIA, sum of the concentrations of SO42−, NO3− and NH4+) correlate negatively with OP μg⁻¹ at considerable significance level (p < 0.05). Negative correlation of SIA with OP μg⁻¹ has been assessed in laboratory experiment and attributed to their DTT inactive nature. It is suggested to use WSOC/SIA ratio as a measure of DTT activity of secondary particles over the study region. Further, biomass burning derived species are observed to be more DTT active than those derived from fossil fuel burning. It was also observed that the slope of OP μg⁻¹ and WSOC/SIA ratio linear relationship enhances significantly in samples collected during days following foggy nights in comparison to that in samples collected during non-foggy period, which may be due to the production of redox-active species by fog processing. Such studies have implications in assessing the effect of ambient aerosol on atmospheric chemistry, air quality and human health.



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Cloud condensation nuclei activity and hygroscopicity of fresh and aged cooking organic aerosol

Publication date: March 2018
Source:Atmospheric Environment, Volume 176
Author(s): Yanwei Li, Antonios Tasoglou, Aikaterini Liangou, Kerrigan P. Cain, Leif Jahn, Peishi Gu, Evangelia Kostenidou, Spyros N. Pandis
Cooking organic aerosol (COA) is potentially a significant fraction of organic particulate matter in urban areas. COA chemical aging experiments, using aerosol produced by grilling hamburgers, took place in a smog chamber in the presence of UV light or excess ozone. The water solubility distributions, cloud condensation nuclei (CCN) activity, and corresponding hygroscopicity of fresh and aged COA were measured. The average mobility equivalent activation diameter of the fresh particles at 0.4% supersaturation ranged from 87 to 126 nm and decreased for aged particles, ranging from 65 to 88 nm. Most of the fresh COA had water solubility less than 0.1 g L⁻¹, even though the corresponding particles were quite CCN active. After aging, the COA fraction with water solubility greater than 0.1 g L⁻¹ increased more than 2 times. Using the extended Köhler theory for multiple partially soluble components in order to predict the measured activation diameters, the COA solubility distribution alone could not explain the CCN activity. Surface tensions less than 30 dyn cm⁻¹ were required to explain the measured activation diameters. In addition, COA particles appear to not be spherical, which can introduce uncertainties into the corresponding calculations.



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Use of cameras for monitoring visibility impairment

Publication date: February 2018
Source:Atmospheric Environment, Volume 175
Author(s): William Malm, Scott Cismoski, Anthony Prenni, Melanie Peters
Webcams and automated, color photography cameras have been routinely operated in many U.S. national parks and other federal lands as far back as 1988, with a general goal of meeting interpretive needs within the public lands system and communicating effects of haze on scenic vistas to the general public, policy makers, and scientists. Additionally, it would be desirable to extract quantifiable information from these images to document how visibility conditions change over time and space and to further reflect the effects of haze on a scene, in the form of atmospheric extinction, independent of changing lighting conditions due to time of day, year, or cloud cover. Many studies have demonstrated a link between image indexes and visual range or extinction in urban settings where visibility is significantly degraded and where scenes tend to be gray and devoid of color. In relatively clean, clear atmospheric conditions, clouds and lighting conditions can sometimes affect the image radiance field as much or more than the effects of haze. In addition, over the course of many years, cameras have been replaced many times as technology improved or older systems wore out, and therefore camera image pixel density has changed dramatically. It is shown that gradient operators are very sensitive to image resolution while contrast indexes are not. Furthermore, temporal averaging and time of day restrictions allow for developing quantitative relationships between atmospheric extinction and contrast-type indexes even when image resolution has varied over time. Temporal averaging effectively removes the variability of visibility indexes associated with changing cloud cover and weather conditions, and changes in lighting conditions resulting from sun angle effects are best compensated for by restricting averaging to only certain times of the day.



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Spatial and temporal variation in sources of atmospheric nitrogen deposition in the Rocky Mountains using nitrogen isotopes

Publication date: March 2018
Source:Atmospheric Environment, Volume 176
Author(s): Leora Nanus, Donald H. Campbell, Christopher M.B. Lehmann, M. Alisa Mast
Variation in source areas and source types of atmospheric nitrogen (N) deposition to high-elevation ecosystems in the Rocky Mountains were evaluated using spatially and temporally distributed N isotope data from atmospheric deposition networks for 1995-2016. This unique dataset links N in wet deposition and snowpack to mobile and stationary emissions sources, and enhances understanding of the impacts of anthropogenic activities and environmental policies that mitigate effects of accelerated N cycling across the Rocky Mountain region. δ¹⁵N−NO3⁻ at 50 U.S. Geological Survey Rocky Mountain Snowpack (Snowpack) sites ranged from −3.3‰ to +6.5‰, with a mean value of +1.4‰. At 15 National Atmospheric Deposition Program (NADP)/National Trends Network wet deposition (NADP Wetfall) sites, summer δ¹⁵N−NO3⁻ is significantly lower ranging from −7.6‰ to −1.3‰ while winter δ¹⁵N−NO3⁻ ranges from −2.6‰ to +5.5‰, with a mean value of +0.7‰ during the cool season. The strong seasonal difference in NADP Wetfall δ¹⁵N−NO3⁻ is due in part to variation in the proportion of N originating from source regions at different times of the year due to seasonal changes in weather patterns. Snowpack NO3⁻ and δ¹⁵N−NO3⁻ are significantly related to NADP Wetfall (fall and winter) suggesting that bulk snowpack samples provide a reliable estimate at high elevations. Spatial trends show higher NO3⁻ concentrations and δ¹⁵N−NO3⁻ in the Southern Rocky Mountains located near larger anthropogenic N emission sources compared to the Northern Rocky Mountains. NADP Wetfall δ¹⁵N−NH4⁺ ranged from −10‰ to 0‰, with no observed spatial pattern. However, the lowest δ¹⁵N−NH4⁺(−9‰), and the highest NH4⁺ concentration (35 μeq/L) were observed at a Utah site dominated by local agricultural activities, whereas the higher δ¹⁵N−NH4⁺ observed in Colorado and Wyoming are likely due to mixed sources, including fossil fuel combustion and agricultural sources. These findings show spatial and seasonal variation in N isotope data that reflect differences in sources of anthropogenic N deposition to high-elevation ecosystems and have important implications for environmental policy across the Rocky Mountain region.



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High contributions of vehicular emissions to ammonia in three European cities derived from mobile measurements

Publication date: February 2018
Source:Atmospheric Environment, Volume 175
Author(s): Miriam Elser, Imad El-Haddad, Marek Maasikmets, Carlo Bozzetti, Robert Wolf, Giancarlo Ciarelli, Jay G. Slowik, Rene Richter, Erik Teinemaa, Christoph Hüglin, Urs Baltensperger, André S.H. Prévôt
Ambient ammonia (NH3) measurements were performed with a mobile platform in three European cities: Zurich (Switzerland), Tartu (Estonia) and Tallinn (Estonia) deploying an NH3 analyzer based on cavity ring-down spectroscopy. A heated inlet line along with an auxiliary flow was used to minimize NH3 adsorption onto the inlet walls. In addition, a detailed characterization of the response and recovery times of the measurement system was used to deconvolve the true NH3 signal from the remaining adsorption-induced hysteresis. Parallel measurements with an aerosol mass spectrometer were used to correct the observed NH3 for the contribution of ammonium nitrate, which completely evaporated in the heated line at the chosen temperature, in contrast to ammonium sulfate. In this way a quantitative measurement of ambient gaseous NH3 was achieved with sufficient time resolution to enable measurement of NH3 point sources with a mobile sampling platform. The NH3 analyzer and the aerosol mass spectrometer were complemented by an aethalometer and various gas-phase analyzers to enable a complete characterization of the sources of air pollution, including the spatial distributions and the regional background concentrations and urban increments of all measured components. Although at all three locations similar increment levels of organic aerosols were attributed to biomass burning and traffic, traffic emissions clearly dominated the city enhancements of NH3, equivalent black carbon (eBC) and carbon dioxide (CO2). Urban increments of 3.4, 1.8 and 3.0 ppb of NH3 were measured in the traffic areas in Zurich, Tartu and Tallinn, respectively, representing an enhancement of 36.6, 38.3 and 93.8% over the average background concentrations. Measurements in areas strongly influenced by traffic emissions (including tunnel drives) were used to estimate emission factors (EF) for the traffic-related pollutants. The obtained median EFs range between 136.8-415.1 mg kg⁻¹ fuel for NH3, 157.1–734.8 mg kg⁻¹ fuel for eBC and 39.9–324.3 mg kg⁻¹ fuel for HOA. Significant differences were found between the EFs of certain components in the three cities, which were partially linked to an older vehicle fleet in Estonia compared to Switzerland. Using the determined EFs we show that traffic can fully explain the NH3 enhancements in the three cities and also presents a non-negligible fraction of the background concentrations, which are mostly related to agricultural activities. Moreover, the estimated total contribution of traffic to NH3 at all three locations is in good agreement with the available emission inventories.

Graphical abstract

http://ift.tt/2lWq4wU

City-level variations in NOx emissions derived from hourly monitoring data in Chicago

Publication date: March 2018
Source:Atmospheric Environment, Volume 176
Author(s): Benjamin de Foy
Control on emissions of nitrogen oxides (NOx) in the United States of America have led to reductions in concentrations in urban areas by up to a factor of two in the last decade. The Air Quality System monitoring network provides surface measurements of concentrations at hourly resolution over multiple years, revealing variations at the annual, seasonal, day of week and diurnal time scales. A multiple linear regression model was used to estimate the temporal profiles in the NOx concentrations as well as the impact of meteorology, ozone concentrations, and boundary layer heights. The model is applied to data from 2005 to 2016 available at 6 sites in Chicago, Illinois. Results confirm the 50% decrease in NOx over the length of the time series. The weekend effect is found to be stronger in more commercial areas, with 32% reductions on Saturdays and 45% on Sundays and holidays; and weaker in more residential areas with 20% reductions on Saturdays and 30% reductions on Sundays. Weekday diurnal profiles follow a double hump with emission peaks during the morning and afternoon rush hours, but only a shallow drop during the middle day. Difference in profiles from the 6 sites suggest that there are different emission profiles within the urban area. Diurnal profiles on Saturdays have less variation throughout the day and more emissions in the evening. Sundays are very different from both weekdays and Saturdays with a gradual increase until the early evening. The results suggest that in addition to vehicle type and vehicle miles traveled, vehicle speed and congestion must be taken into account to correctly quantify morning rush hour emissions and the weekend effect.

Graphical abstract

http://ift.tt/2lYmoen

Identification and semi-quantification of biogenic organic nitrates in ambient particulate matters by UHPLC/ESI-MS

Publication date: March 2018
Source:Atmospheric Environment, Volume 176
Author(s): Rui Li, Xinfeng Wang, Rongrong Gu, Chunying Lu, Fanping Zhu, Likun Xue, Huijun Xie, Lin Du, Jianmin Chen, Wenxing Wang
Particulate biogenic organic nitrates (PBONs) are important components of secondary organic aerosols and play an important role in the tropospheric atmosphere chemistry. However, the concentrations and the chemistry of PBONs remain poorly understood due to the lack of accurate measurement techniques on specific organic nitrates. In this study, ultra high performance liquid chromatography/electrospray mass spectrometry was applied in detection of individual PBONs in ambient atmosphere. Total five kinds of PBONs were identified in PM2.5 samples collected in urban Ji'nan in spring according to characteristic fragments of NO2, NO3, HNO3, CO2, and H2O, including monoterpene hydroxyl nitrate (MW = 215, MHN215), pinene keto nitrate (MW = 229, PKN229), limonene di-keto nitrate (MW = 247, LDKN247), oleic acid keto nitrate (MW = 359, OAKN359), and oleic acid hydroxyl nitrate (MW = 361, OAHN361). Among them, three kinds of PBONs originated from biogenic volatile organic compounds of pinene and limonene and two kinds of PBONs came from chemical conversion of oleic acid. The concentrations of these PBONs were roughly quantified with surrogate standards of (1R,2R,5R)-(+)-2-hydroxy-3-pinanone and ricinoleic acid. The average concentrations of MHN215, PKN229, LDKN247, OAKN359, and OAHN361 were 111.6 ± 23.0, 93.1 ± 49.6, 55.3 ± 7.4, 23.4 ± 14.5, 36.8 ± 18.3 ng m⁻³, respectively. The total concentration of these PBONs was 325.4 ± 116.7 ng m⁻³, contributing to 1.64 ± 0.34‰ of PM2.5.



http://ift.tt/2lWatNO

Genotoxic effects of daily personal exposure to particle mass and number concentrations on buccal cells

Publication date: March 2018
Source:Atmospheric Environment, Volume 176
Author(s): Daniela S. de Almeida, Silvano César da Costa, Marcos Ribeiro, Camila A.B. Moreira, Alexandra Beal, Rafaela Squizzato, Anderson Paulo Rudke, Sameh Adib Abou Rafee, Jorge A. Martins, Graciana Freitas Palioto, Prashant Kumar, Leila D. Martins
The aim of this study is to assess personal exposure to Particle Number Concentrations (PNC) in four size ranges between 0.3 and 10 μm, and particulate matter (PM1; PM2.5; PM4; PM10) in order to evaluate possible genotoxic effects through a comet assay in buccal cells. A convenience cohort of 30 individuals from a Brazilian medium-sized city was selected. These individuals aged between 20 and 61 and worked in typical job categories (i.e., administrative, commerce, education, general services and transport). They were recruited to perform personal exposure measurements during their typical daily routine activities, totaling 240 h of sampling. The 8-h average mass concentrations in air for volunteers ranged from 2.4 to 31.8 μg m⁻³ for PM1, 4.2–45.1 μg m⁻³ for PM2.5, 7.9–66.1 μg m⁻³ for PM4 and from 23.1 to 131.7 μg m⁻³ for PM10. The highest PNC variation was found for 0.3–0.5 range, between 14 and 181 particles cm⁻³, 1 to 14 particles cm⁻³ for the 0.5–1.0 range, 0.2 to 2 particles cm⁻³ for the 1.0–2.5 range, and 0.06 to 0.7 particles cm⁻³ for the 2.5–10 range. Volunteers in the 'education' category experienced the lowest inhaled dose of PM2.5, as opposed to those involved in 'commercial' activities with the highest doses for PM10 (1.63 μg kg⁻¹ h⁻¹) and PM2.5 (0.61 μg kg⁻¹ h⁻¹). The predominant cause for these high doses was associated with the proximity of the workplace to the street and vehicle traffic. The comet assay performed in buccal cells indicated that the volunteers in 'commerce' category experienced the highest damage to their DeoxyriboNucleic Acid (DNA) compared with the control category (i.e. 'education'). These results indicate the variability in personal exposure of the volunteers in different groups, and the potential damage to DNA was much higher for those spending time in close proximity to the vehicle sources (e.g. commercial services) leading to exposure to a higher fraction of fine particles. This study builds understanding on the exposure of people in different job categories, and provide policy makers with useful information to tackle this neglected issue.

Graphical abstract

http://ift.tt/2CCKnKn

Black carbon emissions from biomass and coal in rural China

Publication date: March 2018
Source:Atmospheric Environment, Volume 176
Author(s): Weishi Zhang, Zifeng Lu, Yuan Xu, Can Wang, Yefu Gu, Hui Xu, David G. Streets
Residential solid fuel combustion makes a major contribution to black carbon (BC) emissions in China. A new estimation of BC emissions from rural solid biomass and coal consumption has been derived from field survey data. The following new contributions are made: (1) emission factors are collected and reviewed; (2) household energy data are collected from field survey data and from the literature; (3) a new extrapolation method is developed to extend the field survey data to other locations; (4) the ownership and usage of two stove types are estimated and considered in the emission calculations; and (5) uncertainties associated with the estimation results are quantified. It is shown that rural households with higher income will consume less biomass but more coal. Agricultural acreage and temperature also significantly influence the amount of solid fuel consumed in rural areas. It is estimated that 640 ± 245 Gg BC/y were emitted to the atmosphere due to residential solid fuel consumption in rural China in 2014. Emissions of BC from straw, wood, and coal contributed 42 ± 13%, 36 ± 15%, and 22 ± 10% of the total, respectively. We show that effective BC mitigation (a reduction of 47%) could be obtained through widespread introduction of improved stoves in rural households.



http://ift.tt/2CF1F9x

Tracer element for indoor PM2.5 in China migrated from outdoor

Publication date: March 2018
Source:Atmospheric Environment, Volume 176
Author(s): Wenjing Ji, Hongyu Li, Bin Zhao, Furong Deng
Sulfur and nickel have been widely used as tracers of outdoor PM2.5 (particulate matter with an aerodynamic diameter ≤ 2.5 μm) in the United States and Europe; however, their feasibility as tracers has not been verified yet in China. We aim to verify whether sulfur or nickel could be used as a tracer element and, if not, to identify a suitable tracer element for outdoor PM2.5 in China. We conduct two types of experiments, namely, preliminary and main-study experiments. We analyze 102 pairs of indoor and outdoor PM2.5 samples in Beijing. The correlation between the I/O (indoor/outdoor) ratio of an element and the I/O ratio of total PM2.5 is one of the criteria used to test whether this element can be used as a tracer element. The average concentrations of nickel are found to be below the detection limits in both preliminary and main-study tests. Thus, nickel cannot be used as a tracer element in China. Based on the correlations of elemental I/O ratios and the I/O ratio of total PM2.5 in the preliminary and main-study tests, sulfur also cannot be used as a tracer element; however, it should be feasible to use iron as a tracer element in Beijing according to the test results. The estimated infiltration factor obtained by using iron as tracer is extremely consistent with the calculations based on the mass balance model. In summary, iron is found to be more suitable as a tracer for outdoor PM2.5 in Beijing than sulfur or nickel.

Graphical abstract

http://ift.tt/2lV5ooZ

Emissions of volatile organic compounds from maize residue open burning in the northern region of Thailand

Publication date: March 2018
Source:Atmospheric Environment, Volume 176
Author(s): Duanpen Sirithian, Sarawut Thepanondh, Melanie L. Sattler, Wanna Laowagul
Emission factors for speciated volatile organic compounds (VOCs) from maize residue burning were determined in this study based on chamber experiments. Thirty-six VOC species were identified by Gas Chromatography/Mass Spectrometer (GC/MS). They were classified into six groups, including alkanes, alkenes, oxygenated VOCs, halogenated VOCs, aromatics and other. The emission factor for total VOCs was estimated as about 148 mg kg⁻¹ dry mass burned. About 68.4% of the compounds were aromatics. Field samplings of maize residues were conducted to acquire the information of fuel characteristics including fuel loading, fraction of maize residues that were actually burned as well as proximate and elemental analysis of maize residues. The emission factors were then applied to estimate speciated VOC emissions from maize residue open burning at the provincial level in the upper-northern region of Thailand for the year 2014. Total burned area of maize covered an area of about 500,000 ha which was about 4.7% of the total area of upper-northern region of the country. It was found that total VOC emissions released during the burning season (January–April) was about 79.4 tons. Ethylbenzene, m,p-xylene, 1,2,4-trimethylbenzene, acetaldehyde and o-xylene were the major contributors, accounting for more than 65% of total speciated VOC emissions.



http://ift.tt/2lUP5c3

Analysis of reaction products formed in the gas phase reaction of E,E-2,4-hexadienal with atmospheric oxidants: Reaction mechanisms and atmospheric implications

Publication date: March 2018
Source:Atmospheric Environment, Volume 176
Author(s): I. Colmenar, P. Martin, B. Cabañas, S. Salgado, E. Martinez
An analysis of reaction products for the reaction of E,E-2,4-hexadienal with chlorine atoms (Cl) and OH and NO3 radicals has been carried out at the first time with the aim of obtaining a better understanding of the tropospheric reactivity of α,β-unsaturated carbonyl compounds. Fourier Transform Infrared (FTIR) spectroscopy and Gas Chromatography-Mass Spectrometry with a Time of Flight detector (GC-TOFMS) were used to carry out the qualitative and/or quantitative analyses. Reaction products in gas and particulate phase were observed from the reactions of E,E-2,4- hexadienal with all oxidants. E/Z-Butenedial and maleic anhydride were the main products identified in gas phase. E-butenedial calculated molar yield ranging from 4 to 10%. A significant amount of multifunctional compounds (chloro and hydroxy carbonyls) was identified. These compounds could be formed in particulate phase explaining the ∼90% of unaccounted carbon in gas phase. The reaction with Cl atoms in the presence of NOx with a long reaction time gave Peroxy Acetyl Nitrate (PAN) as an additional product, which is known for being an important specie in the generation of the photochemical smog. Nitrated compounds were the major organic products from the reaction with the NO3 radical. Based on the identified products, the reaction mechanisms have been proposed. In these mechanisms a double bond addition of the atmospheric oxidant at C4/C5 of E,E-2,4-hexadienal is the first step for tropospheric degradation.



http://ift.tt/2CGGbcg

Low-Intensity Ultrasound Reduces High Glucose-Induced Nitric Oxide Generation in Retinal Pigment Epithelial Cells

Publication date: Available online 4 January 2018
Source:Ultrasound in Medicine & Biology
Author(s): Mrigendra Bir Karmacharya, Binika Hada, So Ra Park, Byung Hyune Choi
Diabetic retinopathy (DR) is a severe micro-vascular complication of diabetes. High glucose (HG)-evoked nitric oxide (NO) production mediated by increased oxidative stress is a key factor in DR pathogenesis. In this study, we examined whether low-intensity ultrasound (LIUS) stimulation can reduce HG-induced NO generation. We determined that LIUS stimulation decreased the HG-induced NO generation possibly via inhibition of reactive oxygen species (ROS) and subsequently diminished the associated pro-inflammatory pathway involving the induced expression of inducible nitric oxide synthase, cyclooxygenase-2 and vascular endothelial growth factor. In addition, we determined that LIUS stimulation reduced the quantity of NO produced by N-acetylcysteine, which was not mediated by ROS. These results indicate that LIUS can inhibit both ROS-dependent and -independent NO generation processes in ARPE-19 cells. We envision LIUS as a potential therapeutic alternative to treat DR. Further studies are required to understand the underlying mechanism of the LIUS-induced reduction of NO generation for DR therapy.



http://ift.tt/2CUkQK8

Maximum standard metabolic rate corresponds with the salinity of maximum growth in hatchlings of the estuarine northern diamondback terrapin (Malaclemys terrapin terrapin): Implications for habitat conservation

Publication date: January 2018
Source:Acta Oecologica, Volume 86
Author(s): Christopher L. Rowe
I evaluated standard metabolic rates (SMR) of hatchling northern diamondback terrapins (Malaclemys terrapin terrapin) across a range of salinities (salinity = 1.5, 4, 8, 12, and 16 psu) that they may encounter in brackish habitats such as those in the Maryland portion of the Chesapeake Bay, U.S.A. Consumption of O2 and production of CO2 by resting, unfed animals served as estimates of SMR. A peak in SMR occurred at 8 psu which corresponds closely with the salinity at which hatchling growth was previously shown to be maximized (salinity ∼ 9 psu). It appears that SMR is influenced by growth, perhaps reflecting investments in catabolic pathways that fuel anabolism. This ecophysiological information can inform environmental conservation and management activities by identifying portions of the estuary that are bioenergetically optimal for growth of hatchling terrapins. I suggest that conservation and restoration efforts to protect terrapin populations in oligo-to mesohaline habitats should prioritize protection or creation of habitats in regions where average salinity is near 8 psu and energetic investments in growth appear to be maximized.



http://ift.tt/2lZGAgH

A Coated Sponge: Toward Neonatal Brain Repair

Publication date: 4 January 2018
Source:Cell Stem Cell, Volume 22, Issue 1
Author(s): Orly Reiner, Tamar Sapir
In this issue of Cell Stem Cell, Jinnou et al. (2018) identify a limited time window wherein neonatal brain injuries may be treated through neuroblast migration toward the injury site on radial glial fibers. Implanting a sponge coated with an adhesive factor in the injured neonatal brain supports the migration of neuroblasts and improves functional recovery.

Teaser

In this issue of Cell Stem Cell, Jinnou et al. (2018) identify a limited time window wherein neonatal brain injuries may be treated through neuroblast migration toward the injury site on radial glial fibers. Implanting a sponge coated with an adhesive factor in the injured neonatal brain supports the migration of neuroblasts and improves functional recovery.


http://ift.tt/2CVZcWa

Chewing through Roots: How Leukemia Invades and Disrupts the Bone Marrow Microenvironment

Publication date: 4 January 2018
Source:Cell Stem Cell, Volume 22, Issue 1
Author(s): Owen J. Tamplin
The bone marrow (BM) niche is a complex microenvironment that supports healthy hematopoietic stem cells (HSCs) throughout life. In this issue of Cell Stem Cell, Duarte et al. (2018) reveal the spatio-temporal progress of leukemic cells as they invade and occupy the niche, ultimately outcompeting native HSCs.

Teaser

The bone marrow (BM) niche is a complex microenvironment that supports healthy hematopoietic stem cells (HSCs) throughout life. In this issue of Cell Stem Cell, Duarte et al. (2018) reveal the spatio-temporal progress of leukemic cells as they invade and occupy the niche, ultimately outcompeting native HSCs.


http://ift.tt/2CsavUX

Think About the Environment: Cellular Reprogramming by the Extracellular Matrix

Publication date: 4 January 2018
Source:Cell Stem Cell, Volume 22, Issue 1
Author(s): David J. Huels, Jan Paul Medema
In this issue of Cell Stem Cell, Yui et al. (2018) show how tissue regeneration is driven by changes in the microenvironment. During intestinal regeneration, the epithelium is reprogrammed into a fetal state by an altered extracellular matrix (ECM), which is dependent on YAP/TAZ activation.

Teaser

In this issue of Cell Stem Cell, Yui et al. (2018) show how tissue regeneration is driven by changes in the microenvironment. During intestinal regeneration, the epithelium is reprogrammed into a fetal state by an altered extracellular matrix (ECM), which is dependent on YAP/TAZ activation.


http://ift.tt/2CUSM9r

Turning up the Heat with Therapeutic Epigenome Editing

Publication date: 4 January 2018
Source:Cell Stem Cell, Volume 22, Issue 1
Author(s): Alexandra Zezulin, Kiran Musunuru
CRISPR-Cas9 has been touted for therapeutic genome editing, but limitations include inefficient correction of disease-causing mutations and off-target mutagenesis. In the latest issue of Cell, Liao et al. (2017) show that a modified version of CRISPR-Cas9 can target and activate key therapeutic genes in vivo without altering DNA sequence identity.

Teaser

CRISPR-Cas9 has been touted for therapeutic genome editing, but limitations include inefficient correction of disease-causing mutations and off-target mutagenesis. In the latest issue of Cell, Liao et al. show that a modified version of CRISPR-Cas9 can target and activate key therapeutic genes in vivo without altering DNA sequence identity.


http://ift.tt/2CqZGlP

Alpha to Beta Cell Reprogramming: Stepping toward a New Treatment for Diabetes

Publication date: 4 January 2018
Source:Cell Stem Cell, Volume 22, Issue 1
Author(s): Anna B. Osipovich, Mark A. Magnuson
Beta cell replacement strategies hold promise for permanently treating type 1 diabetes. In Cell Stem Cell, Xiao et al. (2018) restore pancreatic beta cell mass and normalize blood glucose in diabetic mice by reprogramming pancreatic alpha to beta cells using Pdx1- and Mafa-expressing adeno-associated virus infused into the pancreatic duct.

Teaser

Beta cell replacement strategies hold promise for permanently treating type 1 diabetes. In Cell Stem Cell, Xiao et al. restore pancreatic beta cell mass and normalize blood glucose in diabetic mice by reprogramming pancreatic alpha to beta cells using Pdx1- and Mafa-expressing adeno-associated virus infused into the pancreatic duct.


http://ift.tt/2CXKHBa

Self-Renewal and Lineage Transitions

Publication date: 4 January 2018
Source:Cell Stem Cell, Volume 22, Issue 1
Author(s): Sheila Chari




http://ift.tt/2Cw2FJX

The Skin(ny) on Regenerating the Largest Organ to Save a Patient’s Life

Publication date: 4 January 2018
Source:Cell Stem Cell, Volume 22, Issue 1
Author(s): Rui Yi
Stem cells hold enormous potential to regenerate an entire organ for organ replacement therapy. Recently, in Nature, Hirsch et al. (2017) restored the expression of laminin-332 in epidermal stem cells isolated from an individual with junctional epidermolysis bullosa and grafted the entire skin back to save the patient's life.

Teaser

Stem cells hold enormous potential to regenerate an entire organ for organ replacement therapy. Recently, in Nature, Hirsch et al. (2017) restored the expression of laminin-332 in epidermal stem cells isolated from an individual with junctional epidermolysis bullosa and grafted the entire skin back to save the patient's life.


http://ift.tt/2CVb6zu

Ihor R. Lemischka (1953–2017)

Publication date: 4 January 2018
Source:Cell Stem Cell, Volume 22, Issue 1
Author(s): Natalia Ivanova, Carlos-Filipe Pereira, Dung-Fang Lee




http://ift.tt/2CVbga4

Mentoring the Next Generation: Brigid Hogan

Publication date: 4 January 2018
Source:Cell Stem Cell, Volume 22, Issue 1

Mentor-mentee relationships are essential for professional development, but developing these interpersonal skills is not often highlighted as a priority in scientific endeavors. In a yearlong series, Cell Stem Cell interviews prominent scientists who have prioritized mentorship over the years. Here, we chat with Dr. Brigid Hogan about her views.



http://ift.tt/2Cre3qm

iPSC-Derived Organs In Vivo: Challenges and Promise

Publication date: 4 January 2018
Source:Cell Stem Cell, Volume 22, Issue 1
Author(s): Fabian Suchy, Tomoyuki Yamaguchi, Hiromitsu Nakauchi
Transplanting iPSCs into the embryos of another species can generate functional organs for basic research and translational applications. We discuss forward-looking approaches and address key remaining challenges of generating iPSC-derived human organs in vivo.

Teaser

Transplanting iPSCs into the embryos of another species can generate functional organs for basic research and translational applications. We discuss forward-looking approaches and address key remaining challenges of generating iPSC-derived human organs in vivo.


http://ift.tt/2CTDmT0

Capturing Totipotent Stem Cells

Publication date: 4 January 2018
Source:Cell Stem Cell, Volume 22, Issue 1
Author(s): Christopher L. Baker, Martin F. Pera
Minority subpopulations within embryonic stem cell cultures display an expanded developmental potential similar to that of early embryo blastomeres or the early inner cell mass. The ability to isolate and culture totipotent cells capable of giving rise to the entire conceptus would enhance our capacity to study early embryo development, and might enable more efficient generation of chimeric animals for research and organ production for transplantation. Here we review the biological and molecular characterization of cultured cells with developmental potential similar to totipotent blastomeres, and assess recent progress toward the capture and stabilization of the totipotent state in vitro.

Teaser

Baker and Pera review the biological and molecular characterization of cultured cells with developmental potential similar to totipotent blastomeres, and assess recent progress toward the capture and stabilization of the totipotent state in vitro.


http://ift.tt/2CrdX1Y

Endogenous Reprogramming of Alpha Cells into Beta Cells, Induced by Viral Gene Therapy, Reverses Autoimmune Diabetes

Publication date: 4 January 2018
Source:Cell Stem Cell, Volume 22, Issue 1
Author(s): Xiangwei Xiao, Ping Guo, Chiyo Shiota, Ting Zhang, Gina M. Coudriet, Shane Fischbach, Krishna Prasadan, Joseph Fusco, Sabarinathan Ramachandran, Piotr Witkowski, Jon D. Piganelli, George K. Gittes
Successful strategies for treating type 1 diabetes need to restore the function of pancreatic beta cells that are destroyed by the immune system and overcome further destruction of insulin-producing cells. Here, we infused adeno-associated virus carrying Pdx1 and MafA expression cassettes through the pancreatic duct to reprogram alpha cells into functional beta cells and normalized blood glucose in both beta cell-toxin-induced diabetic mice and in autoimmune non-obese diabetic (NOD) mice. The euglycemia in toxin-induced diabetic mice and new insulin⁺ cells persisted in the autoimmune NOD mice for 4 months prior to reestablishment of autoimmune diabetes. This gene therapy strategy also induced alpha to beta cell conversion in toxin-treated human islets, which restored blood glucose levels in NOD/SCID mice upon transplantation. Hence, this strategy could represent a new therapeutic approach, perhaps complemented by immunosuppression, to bolster endogenous insulin production. Our study thus provides a potential basis for further investigation in human type 1 diabetes.

Graphical abstract

Teaser

Reprograming of endogenous mouse alpha cells into functional beta cells, which significantly delays diabetes onset in autoimmune diabetic mice, and the successful reprograming of human alpha cells into beta cells with the same strategy represent a promising way for treating type 1 diabetes.


http://ift.tt/2CVvIaO

A Coated Sponge: Toward Neonatal Brain Repair

Publication date: 4 January 2018
Source:Cell Stem Cell, Volume 22, Issue 1
Author(s): Orly Reiner, Tamar Sapir
In this issue of Cell Stem Cell, Jinnou et al. (2018) identify a limited time window wherein neonatal brain injuries may be treated through neuroblast migration toward the injury site on radial glial fibers. Implanting a sponge coated with an adhesive factor in the injured neonatal brain supports the migration of neuroblasts and improves functional recovery.

Teaser

In this issue of Cell Stem Cell, Jinnou et al. (2018) identify a limited time window wherein neonatal brain injuries may be treated through neuroblast migration toward the injury site on radial glial fibers. Implanting a sponge coated with an adhesive factor in the injured neonatal brain supports the migration of neuroblasts and improves functional recovery.


http://ift.tt/2CVZcWa

Chewing through Roots: How Leukemia Invades and Disrupts the Bone Marrow Microenvironment

Publication date: 4 January 2018
Source:Cell Stem Cell, Volume 22, Issue 1
Author(s): Owen J. Tamplin
The bone marrow (BM) niche is a complex microenvironment that supports healthy hematopoietic stem cells (HSCs) throughout life. In this issue of Cell Stem Cell, Duarte et al. (2018) reveal the spatio-temporal progress of leukemic cells as they invade and occupy the niche, ultimately outcompeting native HSCs.

Teaser

The bone marrow (BM) niche is a complex microenvironment that supports healthy hematopoietic stem cells (HSCs) throughout life. In this issue of Cell Stem Cell, Duarte et al. (2018) reveal the spatio-temporal progress of leukemic cells as they invade and occupy the niche, ultimately outcompeting native HSCs.


http://ift.tt/2CsavUX

Think About the Environment: Cellular Reprogramming by the Extracellular Matrix

Publication date: 4 January 2018
Source:Cell Stem Cell, Volume 22, Issue 1
Author(s): David J. Huels, Jan Paul Medema
In this issue of Cell Stem Cell, Yui et al. (2018) show how tissue regeneration is driven by changes in the microenvironment. During intestinal regeneration, the epithelium is reprogrammed into a fetal state by an altered extracellular matrix (ECM), which is dependent on YAP/TAZ activation.

Teaser

In this issue of Cell Stem Cell, Yui et al. (2018) show how tissue regeneration is driven by changes in the microenvironment. During intestinal regeneration, the epithelium is reprogrammed into a fetal state by an altered extracellular matrix (ECM), which is dependent on YAP/TAZ activation.


http://ift.tt/2CUSM9r

Turning up the Heat with Therapeutic Epigenome Editing

Publication date: 4 January 2018
Source:Cell Stem Cell, Volume 22, Issue 1
Author(s): Alexandra Zezulin, Kiran Musunuru
CRISPR-Cas9 has been touted for therapeutic genome editing, but limitations include inefficient correction of disease-causing mutations and off-target mutagenesis. In the latest issue of Cell, Liao et al. (2017) show that a modified version of CRISPR-Cas9 can target and activate key therapeutic genes in vivo without altering DNA sequence identity.

Teaser

CRISPR-Cas9 has been touted for therapeutic genome editing, but limitations include inefficient correction of disease-causing mutations and off-target mutagenesis. In the latest issue of Cell, Liao et al. show that a modified version of CRISPR-Cas9 can target and activate key therapeutic genes in vivo without altering DNA sequence identity.


http://ift.tt/2CqZGlP

Alpha to Beta Cell Reprogramming: Stepping toward a New Treatment for Diabetes

Publication date: 4 January 2018
Source:Cell Stem Cell, Volume 22, Issue 1
Author(s): Anna B. Osipovich, Mark A. Magnuson
Beta cell replacement strategies hold promise for permanently treating type 1 diabetes. In Cell Stem Cell, Xiao et al. (2018) restore pancreatic beta cell mass and normalize blood glucose in diabetic mice by reprogramming pancreatic alpha to beta cells using Pdx1- and Mafa-expressing adeno-associated virus infused into the pancreatic duct.

Teaser

Beta cell replacement strategies hold promise for permanently treating type 1 diabetes. In Cell Stem Cell, Xiao et al. restore pancreatic beta cell mass and normalize blood glucose in diabetic mice by reprogramming pancreatic alpha to beta cells using Pdx1- and Mafa-expressing adeno-associated virus infused into the pancreatic duct.


http://ift.tt/2CXKHBa

Self-Renewal and Lineage Transitions

Publication date: 4 January 2018
Source:Cell Stem Cell, Volume 22, Issue 1
Author(s): Sheila Chari




http://ift.tt/2Cw2FJX

The Skin(ny) on Regenerating the Largest Organ to Save a Patient’s Life

Publication date: 4 January 2018
Source:Cell Stem Cell, Volume 22, Issue 1
Author(s): Rui Yi
Stem cells hold enormous potential to regenerate an entire organ for organ replacement therapy. Recently, in Nature, Hirsch et al. (2017) restored the expression of laminin-332 in epidermal stem cells isolated from an individual with junctional epidermolysis bullosa and grafted the entire skin back to save the patient's life.

Teaser

Stem cells hold enormous potential to regenerate an entire organ for organ replacement therapy. Recently, in Nature, Hirsch et al. (2017) restored the expression of laminin-332 in epidermal stem cells isolated from an individual with junctional epidermolysis bullosa and grafted the entire skin back to save the patient's life.


http://ift.tt/2CVb6zu

Thoron exposure in Dutch dwellings – An overview

Publication date: March 2018
Source:Journal of Environmental Radioactivity, Volume 183
Author(s): G. de With, R.C.G.M. Smetsers, H. Slaper, P. de Jong
In the Netherlands considerable attention has been given to the exposure from thoron progeny in dwellings. For this purpose a nationwide survey on the thoron exhalation and thoron progeny concentration has been completed in 2015. Furthermore, extensive laboratory studies have been performed to measure activity concentrations and thoron exhalation rates from regular Dutch building materials. The purpose of this study is to demonstrate if the findings from both field experiments and laboratory results are consistent. For this reason measured properties of building materials and surface barriers, in-situ measurements on air ventilation and thoron(progeny) in dwellings as well as advanced computational modelling on indoor air and aerosol behaviour have been used. The results demonstrate that median and mean thoron progeny concentrations of 0.53 and 0.64 Bq·m⁻³ found in the survey are comparable with the mean concentration of 0.57 Bq·m⁻³ obtained from laboratory testing and calculation. Furthermore, upper thoron progeny concentrations from the survey and the calculations are with respectively 13 and 14 Bq·m⁻³ also in good agreement. Such elevated concentrations lead to an effective doses of around 4 mSv per year. The study also includes worst-case scenarios on the application of surface materials high on ²³²Th, and the expected reduction in thoron progeny when using mainstream mitigation measures.



http://ift.tt/2CVG3Ds

Inventory and vertical distribution of 137Cs, 239+240Pu and 238Pu in soil from Raivavae and Hiva Oa, two French Polynesian islands in the southern hemisphere

Publication date: March 2018
Source:Journal of Environmental Radioactivity, Volume 183
Author(s): P. Bouisset, M. Nohl, A. Bouville, G. Leclerc
Atmospheric nuclear weapons tests carried out by the United States, the former Soviet Union, the United Kingdom, France and China between 1945 and 1980 resulted in radioactive fallout over the earth's surface of long-lived radionuclides, such as ¹³⁷Cs, ^239+240Pu and ²³⁸Pu that could be detected more than 50 years after their production. In addition, the burnup in the upper atmosphere of a thermoelectric generator fueled by ²³⁸Pu, SNAP-9A, contributed to the inventory of ²³⁸Pu deposited on the ground. In order to estimate the deposition densities of ¹³⁷Cs, ^239+240Pu and ²³⁸Pu in French Polynesia, we collected undisturbed soil samples up to 30 cm deep at eight sites in two islands (Hiva Oa, 139°W - 10°S and Raivavae, 148°W - 24°S) in 2015–2016. The top 0–10 cm of the soil cores were sliced into five 2-cm layers and the bottom 10–30 cm into four 5-cm layers for gamma spectrometry and alpha spectrometry measurements. We found that more than 50% of the radioactive inventories are still contained within the first 10 cm and that the average vertical migration velocities of ¹³⁷Cs and Pu are less than 0.2 cm y⁻¹. The average accumulated depositions, deduced from the profile measurements, are 236 ± 11 Bq.m⁻² and 313 ± 39 Bq.m⁻² for ¹³⁷Cs, 12.1 ± 1.5 Bq.m⁻² and 22.1 ± 1.7 Bq.m⁻² for ^239+240Pu, and 1.23 ± 0.46 Bq.m⁻² and 1.58 ± 0.60 Bq.m⁻² for ²³⁸Pu, in Hiva Oa and Raivavae, respectively. The ²³⁸Pu/^239+240Pu ratios are 0.102 ± 0.050 at Hiva Oa and 0.072 ± 0.033 at Raivavae. Both values are higher than the ratio in nuclear weapons tests fallout estimated to be 0.016 in 2016 (Hardy et al., 1973), because of the contribution of ²³⁸Pu fallout from SNAP-9A, which is latitude dependent. The ¹³⁷Cs/^239+240Pu ratios, 19.5 ± 3.2 at Hiva Oa and 14.2 ± 2.8 at Raivavae are in the lower part of the range of values observed in other regions of the world.



http://ift.tt/2CrEa0y

8-Hydroxypyrene-1,3,6-trisulfonic acid trisodium salt (HPTS) based high fluorescent, pH stimuli waterborne polyurethane coatings

Publication date: 31 January 2018
Source:Polymer, Volume 136
Author(s): Rajnish Kumar, Ramkeval Yadav, Mangesh A. Kolhe, Rajesh S. Bhosale, Ramanuj Narayan
8-Hydroxypyrene-1,3,6-trisulfonic acid trisodium salt (HPTS), a water-soluble pyrene dye, was used to develop highly fluorescent waterborne polyurethane (WPU) by physical dispersion in WPU matrix. The presence of negatively charged sulfonate ions in HPTS moiety assisted in homogeneous dispersion of HPTS in WPU matrix. The optical properties of HPTS-WPU emulsion and films were characterized by UV-Vis and PL spectroscopy and observed to exhibit high fluorescence property both in emulsion state as well as in solid state even at very low concentration. The fluorescence intensity was found to increase with increasing weight % of the HPTS dye in WPU matrix. Further, pH sensing behavior of these films was also investigated by exposing to trifluoroacetic acid (TFA) vapor (pka = 0.23) and ammonia (NH3) vapor (pkb = 9.25). Observations revealed that HPTS retained not only its highly green fluorescent nature in WPU matrix but also exhibited pH sensing behavior. The overall analysis suggested that HPTS-WPU could be used to develop an environmentally friendly high fluorescent smart coatings and textiles inheriting real-time pH sensing property.

Graphical abstract

http://ift.tt/2E7U8NA

Preparation of monolithic polycaprolactone foams with controlled morphology

Publication date: 31 January 2018
Source:Polymer, Volume 136
Author(s): Ozgun Can Onder, Emel Yilgor, Iskender Yilgor
Polycaprolactone (PCL) foams were produced by thermally induced phase separation. Tetrahydrofuran/methanol (THF/MeOH) (solvent/non-solvent) mixture was used for the induction of liquid-liquid phase separation of PCL solutions at three different temperatures. Subsequent solvent exchange followed by vacuum drying yielded polymeric foams with different morphologies. Characterization of foams was obtained by scanning electron microscopy, x-ray diffractometry, mercury intrusion porosimetry and compression tests. Influence of polymer concentration (8, 10 and 12 wt%), quench temperature (4, −20 and −80 °C), and THF/MeOH ratio from (42/58) to (54/46) (wt/wt) on the foam formation, morphology and properties were investigated systematically. Lower PCL concentration, lower THF content and higher quench temperature lead to larger pore sizes in the foams obtained. Detailed discussions of the influence of processing parameters on foam structure and porosity, foam density, percent crystallinity and compressive properties are provided. By selectively tuning the process parameters, foams with controlled pore sizes (10–450 μm), porosity (83–91%) and morphology (cellular, bead-like, microspherical) were obtained.

Graphical abstract

http://ift.tt/2E7SlIo

Co association of mucus modulating agents and nanoparticles for mucosal drug delivery

Publication date: Available online 4 January 2018
Source:Advanced Drug Delivery Reviews
Author(s): Catherine Taylor Nordgård, Kurt I. Draget
Nanoparticulate drug delivery systems (nDDS) offer a variety of options when it comes to routes of administration. One possible path is crossing mucosal barriers, such as in the airways and in the GI tract, for systemic distribution or local treatment. The main challenge with this administration route is that the size and surface properties of the nanoparticles, as opposed to small molecular drugs, very often results in mucosal capture, immobilization and removal, which in turn results in a very low bioavailability. Strategies to overcome this challenge do exist, like surface 'stealth' modification with PEG. Here we review an alternative or supplemental strategy, co-association of mucus modulating agents with the nDDS to improve bioavailability, where the nDDS may be surface modified or unmodified. This contribution presents some examples on how possible co-association systems may be achieved, using currently marketed mucolytic drugs, alternative formulations or novel agents.

Graphical abstract

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Diversity and Bioprospecting of Extremely Halophilic Archaea isolated from Algerian Arid and Semi-Arid Wetland Ecosystems for Halophilic-Active Hydrolytic Enzymes

Publication date: Available online 4 January 2018
Source:Microbiological Research
Author(s): Taha Menasria, Margarita Aguilera, Hacène Hocine, Leyla Benammar, Ammar Ayachi, Abdelkrim Si Bachir, Ahmed Dekak, Mercedes Monteoliva-Sánchez
The diversity of haloarchaea associated with different dry salt lakes in northeastern Algeria was investigated together with their potential of hydrolytic enzyme production. A total of 68 aerobic halophilic archaea were isolated from saline sediments. Based on the 16S rRNA gene sequencing, the isolates were assigned to seven phylotypes within the class Halobacteria sequences, namely Haloarcula, Halococcus, Haloferax, Halogeometricum, Haloterrigena, Natrialba, and Natrinema. The results showed that Haloferax group was found to be dominant in all samples (30 isolates) (44%) with high diversity, followed by Halococcus spp. (13%) (9 isolates). All phylotypes are extreme halophiles and thermotolerant with the ability to grow at temperatures up to 48 °C. In addition, the screening for extracellular halophilic enzymes showed that 89.7% of the isolates were able to produce at least two types of the screened enzymes respectively. The strains producing esterase, gelatinase, inulinase, cellulase and protease activities were the most diverse functional group. These data showed an abundant and diverse haloarchaeal community, detected in Algerian wetland ecosystems, presenting a promising source of molecules with important biotechnological applications.



http://ift.tt/2E9RZkB

Functional analysis of an APSES transcription factor (GlSwi6) involved in fungal growth, fruiting body development and ganoderic-acid biosynthesis in Ganoderma lucidum

Publication date: Available online 4 January 2018
Source:Microbiological Research
Author(s): Guang Zhang, Ang Ren, Liang Shi, Jing Zhu, Ailiang Jiang, Dengke Shi, Mingwen Zhao
The APSES transcription factors have been identified as key regulators of fungal development and other biological processes in fungi. In the present study, the function of Ganoderma lucidum GlSwi6, a homolog of Saccharomyces cerevisiae Swi6, was characterized. RNAi was used to examine the function of GlSwi6 in G. lucidum. Silencing GlSwi6 resulted in multiple developmental defects, including reduced fungal growth and increased hyphal branching, and the GlSwi6-silenced strains did not exhibit primordium or fruiting body formation. In addition, the H2O2 and ganoderic-acid (GA) levels of the GlSwi6-silenced strains decreased approximately 50% and 25%, respectively, compared with those of the WT strain. Furthermore, the addition of H2O2 led to the recovery of the GA levels of GlSwi6-silenced strains, implying that GlSwi6 might regulate GA biosynthesis by regulating the intracellular ROS levels. Taken together, these results indicate that GlSwi6 is involved in fungal growth, development and GA biosynthesis in G. lucidum.



http://ift.tt/2EYOq23

Could Ceramides Become the New Cholesterol?

Publication date: Available online 4 January 2018
Source:Cell Metabolism
Author(s): Scott A. Summers
The Mayo Clinic recently introduced a diagnostic test that quantifies plasma ceramides in order to identify patients at risk of major adverse cardiac events. By comparing recent discoveries about these biomarker ceramides with the exhaustive body of literature surrounding cholesterol, Summers aims to highlight important advances and critically needed areas of investigation on this exciting class of bioactive lipids.

Teaser

Scott Summers evaluates the current status of research on ceramides, a lipid implicated in cardiometabolic disorders that shows intriguing parallels with cholesterol.


http://ift.tt/2CHmEZw

Predicting postoperative language outcome using presurgical fMRI, MEG, TMS, and high gamma ECoG

Publication date: Available online 4 January 2018
Source:Clinical Neurophysiology
Author(s): Abbas Babajani-Feremi, Christen M. Holder, Shalini Narayana, Stephen P. Fulton, Asim F. Choudhri, Frederick A. Boop, James W. Wheless
ObjectiveTo predict the postoperative language outcome using the support vector regression (SVR) and results of multimodal presurgical language mapping.MethodsEleven patients with epilepsy received presurgical language mapping using functional MRI (fMRI), magnetoencephalography (MEG), transcranial magnetic stimulation (TMS), and high-gamma electrocorticography (hgECoG), as well as pre- and postoperative neuropsychological evaluation of language. We constructed 15 (2⁴-1) SVR models by considering the extent of resected language areas identified by all subsets of four modalities as input feature vector and the postoperative language outcome as output. We trained and cross-validated SVR models, and compared the cross-validation (CV) errors of all models for prediction of language outcome.ResultsSeven patients had some level of postoperative language decline and two of them had significant postoperative decline in naming. Some parts of language areas identified by four modalities were resected in these patients. We found that an SVR model consisting of fMRI, MEG, and hgECoG provided minimum CV error, although an SVR model consisting of fMRI and MEG was the optimal model that facilitated the best trade-off between model complexity and prediction accuracy.ConclusionsA multimodal SVR can be used to predict the language outcome.SignificanceThe developed multimodal SVR models in this study can be utilized to calculate the language outcomes of different resection plans prior to surgery and select the optimal surgical plan.



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Neurophysiologic characterization of periodic paralysis episode in a patient with Andersen-Tawil syndrome

Publication date: Available online 4 January 2018
Source:Clinical Neurophysiology
Author(s): Catarina Falcão de Campos, Mamede de Carvalho




http://ift.tt/2qvbDFV

The critical warning sign of real-time brainstem auditory evoked potentials during microvascular decompression for hemifacial spasm

Publication date: Available online 4 January 2018
Source:Clinical Neurophysiology
Author(s): Sang-Ku Park, Byung-Euk Joo, Seunghoon Lee, Jeong-A Lee, Jeong-Ho Hwang, Doo-Sik Kong, Dae-Won Seo, Kwan Park, Hoon-Taek Lee
ObjectiveThe aim of this study was to define the critical warning sign of real-time brainstem auditory evoked potential (BAEP) for predicting hearing loss (HL) after microvascular decompression (MVD) for hemifacial spasm (HFS).MethodsNine hundred and thirty-two patients with HFS who underwent MVD with intraoperative monitoring (IOM) of BAEP were analyzed. We used a 43.9 Hz/s stimulation rate and 400 averaging trials to obtain BAEP. To evaluate HL, pure-tone audiometry and speech discrimination scoring were performed before and one week after surgery. We analyzed the incidence for postoperative HL according to BAEP changes and calculated the diagnostic accuracy of significant warning criteria.ResultsOnly 11 (1.2 %) patients experienced postoperative HL. The group showing permanent loss of wave V showed the largest percentage of postoperative HL (p <0.001). No patient who experienced only latency prolongation (≥ 1 ms) had postoperative HL. Loss of wave V and latency prolongation (≥1 ms) with amplitude decrement (≥ 50%) were highly associated with postoperative HL.ConclusionsLoss of wave V and latency prolongation of 1 ms with amplitude decrement ≥ 50% were the critical warning signs of BAEP for predicting postoperative HL.SignificanceThese findings elucidate the critical warning sign of real-time BAEP.



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Characterizing the effects of deep brain stimulation with magnetoencephalography: A review

Publication date: Available online 4 January 2018
Source:Brain Stimulation
Author(s): Irene E. Harmsen, Nathan C. Rowland, Richard A. Wennberg, Andres M. Lozano
BackgroundDeep brain stimulation (DBS) is an important form of neuromodulation that is being applied to patients with motor, mood, or cognitive circuit disorders. Despite the efficacy and widespread use of DBS, the precise mechanisms by which it works remain unknown. Over the last decade, magnetoencephalography (MEG) has become an important functional neuroimaging technique used to study DBS.ObjectiveThis review summarizes the literature related to the use of MEG to characterize the effects of DBS.MethodsPeer reviewed literature on DBS-MEG was obtained by searching the publicly accessible literature databases available on PubMed. The abstracts of all reports were scanned and publications which combined DBS-MEG in human subjects were selected for review.ResultsA total of 32 publications met the selection criteria, and included studies which applied DBS for Parkinson's disease, dystonia, chronic pain, phantom limb pain, cluster headache, and epilepsy. DBS-MEG studies provided valuable insights into network connectivity, pathological coupling, and the modulatory effects of DBS.ConclusionsAs DBS-MEG research continues to develop, we can expect to gain a better understanding of diverse pathophysiological networks and their response to DBS. This knowledge will improve treatment efficacy, reduce side-effects, reveal optimal surgical targets, and advance the development of closed-loop neuromodulation.



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Scalp-recorded high-frequency oscillations in childhood epileptic encephalopathy with continuous spike-and-wave during sleep with different etiologies

Publication date: Available online 4 January 2018
Source:Brain and Development
Author(s): Pan Gong, Jiao Xue, Ping Qian, Haipo Yang, Xiaoyan Liu, Lixin Cai, Kaigui Bian, Zhixian Yang
ObjectiveTo investigate high-frequency oscillations (HFOs) in epileptic encephalopathy with continuous spike-and-wave during sleep (CSWS) with different etiologies.MethodsTwenty-one CSWS patients treated with methylprednisolone were divided into structural group and genetic/unknown group. Comparisons were made between the two etiological groups: selected clinical variables including gender, age parameters, seizure frequencies and antiepileptic drugs; distribution of HFOs in pre-methylprednisolone electroencephalography (EEG) and percentage changes of HFOs and spikes after methylprednisolone treatment.ResultsThere were 7 patients (33%) in structural group and 14 patients (68%) in genetic/unknown group. No significant difference was found between the two groups regarding selected clinical variables. HFOs were found in 12 patients in pre-methylprednisolone EEG. The distribution of HFOs was focal and accordant with lesions in 5 of structural group, and it was also focal but in different brain regions in 7 of genetic/unknown group. The percentage reduction of total HFOs and spikes was 81% (158/195) and 19% (1956/10,037) in structural group, while 98% (315/323) and 55% (6658/12,258) in genetic/unknown group after methylprednisolone treatment.ConclusionThe etiologies had no distinct correlation with some clinical characteristics in CSWS. HFOs recorded on scalp EEG might not only be used as makers of seizure-onset zone (SOZ), but also have association with functional disruption of brain networks. Both HFOs and spikes reduced more in genetic/unknown patients than that in structural patients after methylprednisolone treatment and HFOs were more sensitive to treatment than spikes.



http://ift.tt/2CGyHHg

Involvement of α7nAChR in electroacupuncture relieving neuropathic pain in the spinal cord of rat with spared nerve injury

Publication date: Available online 4 January 2018
Source:Brain Research Bulletin
Author(s): Ying Wang, Qian Jiang, Yang-yang Xia, Zhi-hua Huang, Cheng Huang
Alpha-7 nicotinic acetylcholine receptor (α7nAChR) was reported to be involved in the modulation of neuropathic pain. Electroacupuncture (EA) has therapeutic effects on neuropathic pain induced by nerve injury, but the underlying mechanisms remain unclear. The present study was designed to investigate whether α7nAChR participates in the relieving effects of 2 Hz EA on neuropathic pain. Paw withdrawal threshold (PWT) was measured to study the EA-mediated analgesic effect in a rat model of spared nerve injury (SNI). The spinal α7nAChR and IL-1β expression levels were determined by RT-PCR, Western blot analysis, and immunofluorescence staining. Additionally, immunofluorescence targeting the expression of CD11b, which is a molecular indicator of microglial activation. The results showed that 2 Hz EA stimulation significantly improved the expression of α7nAChR and reduced the production of IL-1β and CD11b in the spinal cord of rats with SNI-induced neuropathic pain, along with the relief of mechanical hypersensitivity after EA treatment. Moreover, intrathecal injection of alpha-bungarotoxin (α-Bgtx), a selective antagonist for α7nAChR, at the dosage of 1.0 μg/kg, not only suppressed the analgesic effect of EA in SNI rats, but also inhibited the enhancement of α7nAChR expression and the reduction of IL-1β expression induced by EA. In conclusion, our study indicated that 2 Hz EA reduces SNI-induced mechanical hypersensitivity via upregulating α7nAChR and downregulating IL-1β and CD11b in the spinal cord of SNI rats, which might be one of the mechanisms underlying its effectiveness in the neuropathic pain.



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ATP-sensitive potassium-channel inhibitor glibenclamide attenuates HPA axis hyperactivity, depression- and anxiety-related symptoms in a rat model of Alzheimer's disease

Publication date: Available online 4 January 2018
Source:Brain Research Bulletin
Author(s): Mohammad Hossein Esmaeili, Behnam Bahari, Ali-Akbar Salari
Affective disorders including depression and anxiety are among the most prevalent behavioral abnormalities in patients with Alzheimer's disease (AD), which affect the quality of life and progression of the disease. Dysregulation of the hypothalamic-pituitary-adrenal-(HPA) axis has been reported in affective disorders and AD. Recent studies revealed that current antidepressant drugs are not completely effective for treating anxiety- and depression-related disorders in people with dementia. ATP-sensitive-potassium-(KATP) channels are well-known to be involved in AD pathophysiology, HPA axis function and the pathogenesis of depression and anxiety-related behaviors. Thus, targeting of KATP channel may be a potential therapeutic strategy in AD. Hence, we investigated the effects of intracerebroventricular injection of Aβ25-35 alone or in combination with glibenclamide, KATP channel inhibitor on depression- and anxiety-related behaviors as well as HPA axis response to stress in rats. To do this, non-Aβ25-35- and Aβ25-35-treated rats were orally treated with glibenclamide, then the behavioral consequences were assessed using sucrose preference, forced swim, light-dark box and plus maze tests. Stress-induced corticosterone levels following forced swim and plus maze tests were also evaluated as indicative of abnormal HPA-axis-function. Aβ25-35 induced HPA axis hyperreactivity and increased depression- and anxiety-related symptoms in rats. Our results showed that blockade of KATP channels with glibenclamide decreased depression- and anxiety-related behaviors by normalizing HPA axis activity in Aβ25-35-treated rats. This study provides additional evidence that Aβ administration can induce depression- and anxiety-like symptoms in rodents, and suggests that KATP channel inhibitors may be a plausible therapeutic strategy for treating affective disorders in AD patients.



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Forging networks and mixing ores: Rethinking the social landscapes of iron metallurgy

Publication date: March 2018
Source:Journal of Anthropological Archaeology, Volume 49
Author(s): Louise Iles
This research explores the networks of technological knowledge that influenced changes in the iron production practices of western Uganda in the second half of the second millennium AD. Temporal and spatial variability in technological processes were observed within the research area, in terms of the style and construction of the furnaces, the use of a manganese-rich flux, and the configuration of tuyères. These shifts were considered in relation to the social dimensions of iron production, specifically the protection of technical knowledge. Informed by ethnographic data from the study area, variations were noted in the participation in, or exclusion from, iron production activity on the basis of gender and clan affiliation. This stands in contrast to ethno-historic accounts that speak of a strongly regulated production environment.This paper considers that an uncritical emphasis on conservatism provides an inadequate framework for addressing long-term change in iron production technologies. It suggests that constellations of knowledge in western Uganda fostered the potential for innovation and experimentation, resulting in dynamic technological practice. This paper urges a more nuanced discussion of how complex metallurgical technologies transform and move within cultural and physical landscapes, with ramifications for how we conceptualize the emergence and adoption of early technologies.



http://ift.tt/2EYqzQ2

Ancient monetization: The case of Classic Maya textiles

Publication date: March 2018
Source:Journal of Anthropological Archaeology, Volume 49
Author(s): Joanne P. Baron
The role played by individuals, markets, and state institutions in the origins of money have been debated by economists, historians, and anthropologists. Two dominant models have emerged: those who see money's function arising out of exchange, and those who see it arising out of the operation of state institutions. Curiously, archaeology has played only a minor role in this debate, with most scholars focused instead on written records and ethnographic parallels to recent non-capitalist societies. Scholarship on monetization has also focused primarily on Eurasian currency and the roots of modern capitalism. In this article, I argue that much can be gained by examining a different context: the origins of textile money in pre-Columbian Mesoamerica, particularly among the Late Classic Maya. During this period, textiles underwent a process of monetization that saw them take on the roles of exchange medium, measure of value, means of payment, and store of wealth. I argue that neither of the dominant models of monetization is sufficient to describe this process. Instead, elements of both models operated simultaneously, as households and state institutions negotiated differing economic strategies.



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Thin-wall injection molding of polystyrene parts with coated and uncoated cavities

Publication date: 5 March 2018
Source:Materials & Design, Volume 141
Author(s): Davide Masato, Marco Sorgato, Maksims Babenko, Ben Whiteside, Giovanni Lucchetta
Low-friction mold surface coatings can be used to promote filling of thin-wall parts through reduction of the melt flow resistance by causing wall slip at the polymer-mold interface. This work investigates the effects of different mold coatings (DLC, CrN and CrTiNbN) on the flow resistance of molten polystyrene in thin-wall injection molding. The design of the mold allowed high-speed visualization of the molten polymer flow during the filling phase and measurement of the velocity profile across the cavity thickness. The evaluation of the speed profiles allowed the characterization of the wall-slip phenomenon, indicating the absence of conventional 'fountain-flow' filling mechanism. The results indicate that a DLC deposited on a chrome substrate can significantly reduce the flow resistance of polystyrene, by increasing the slip velocity of polymer melt in contact with the mold surface. Moreover, the contact angle of molten polystyrene over the considered coatings was found to be inversely proportional to the melt flow resistance, indicating the importance of the adhesion at the polymer-mold interface.

Graphical abstract

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A strategy for constructing superhydrophobic multilayer coatings with self-cleaning properties and mechanical durability based on the anchoring effect of organopolysilazane

Publication date: 5 March 2018
Source:Materials & Design, Volume 141
Author(s): Zhifeng Chen, Guangji Li, Liying Wang, Yinlei Lin, Wei Zhou
Artificial superhydrophobic surfaces suffer from poor mechanical durability. Organopolysilazane (OPSZ), which could anchor to most materials, and fluorinated silica nanoparticles (F-SiO2 NPs) were employed to construct mechanically durable superhydrophobic nanocomposite multilayer coatings. (OPSZ/F-SiO2)n (n=0.5, 1, 1.5, …, 5) coatings were constructed by alternately spraying OPSZ and F-SiO2 NPs layer by layer on glass substrates. With the increase in the number of OPSZ/F-SiO2 bilayers, the surface roughness and hydrophobicity exhibited an overall increasing trend. The coatings with F-SiO2 NPs on the outside possessed slightly rougher surfaces and stronger hydrophobicity than the corresponding coatings with OPSZ on the outside. The coating containing five bilayers exhibited a microscopic rough surface with hierarchical micro/nanoscale structures and superhydrophobicity, with a water contact angle of 158.3° and a sliding angle of 3°. The coating was translucent and possessed a low water droplet adhesive force (13μN) and good self-cleaning properties. It possesses excellent mechanical durability and maintains its superhydrophobicity upon being immersed in strong acid and alkali solutions, presenting broad application prospects. This facile yet universal strategy for constructing superhydrophobic coatings offers an effective solution to the poor mechanical durability of artificial superhydrophobic surfaces and expands the applications of polysilazane for constructing functional surfaces.

Graphical abstract

http://ift.tt/2CFWXZm

Development of melt-stretching technique for manufacturing fully-recyclable thermoplastic honeycombs with tunable cell geometries

Publication date: 5 March 2018
Source:Materials & Design, Volume 141
Author(s): Calvin Moes, Glenn Hibbard
Honeycomb sandwich panels of several cell geometries were created by stretching polycarbonate melts between opposing platens. Perforations for air ingress through one of the platens were employed to enable and direct the formation of cells within the honeycomb, demonstrating a simple means to produce complicated architectures. Platen temperature, consolidation pressure, and platen movement speeds were each investigated to establish a range of effective process parameters. Honeycomb panels were successfully produced with areal densities of 0.18gcm^-2 to 0.42gcm^-2 and panel thicknesses ranging from 6mm to 32mm. The cell geometries were found to be effectively modeled by Voronoi diagrams seeded by the perforations used for air ingress. This model was validated by the successful production of hexagonal-, square-, and triangular-celled honeycombs, as well as an architecture combining all three cell shapes. Analysis of several samples via computed tomography provided insight into the internal distribution of material. Out-of-plane compressive testing was used to probe the mechanical performance of the structures. Minimal variation in buckling strength was found between the different honeycomb geometries, but post-failure behavior was dependent on cell shape.

Graphical abstract

http://ift.tt/2CFWVkc

Exploring AgBixI3x+1 semiconductor thin films for lead-free perovskite solar cells

Publication date: 5 March 2018
Source:Materials & Design, Volume 141
Author(s): Z. Shao, T. Le Mercier, M.B. Madec, Th. Pauporté
Perovskite solar cells are based on organolead halide compounds which are used as highly efficient solar cell absorber materials. However, their lead component is a high human health concern, toxic, and causes strong damages when disperse in the environment. In the present paper, silver iodobismuthate compounds are investigated as lead-free semiconductors in replacement of organolead halide in perovskite solar cells. We describe the design of thin films of AgBixI3x+1 for x composition ranging between 1 and 2.25. The preparation is optimized to get well-crystallized well-covering layers. The prepared compounds are semiconductors, absorbing light below 700nm. Compounds for x<1.5 have a pure rhombohedral phase. Ag2Bi3I11 is crystallized in the pure cubic phase, yields to the layer with the largest grains and is the composition giving the best solar cell power conversion efficiency (PCE). For higher Bi content, a mixture of cubic AgBi3I11 and BiI3 is produced. The device design includes the use of a SnO2 hole blocking layer to get good efficiency. Based on these results it can be concluded that AgBixI3x+1 compounds are potentially promising properties for application in optoelectronic devices.

Graphical abstract

http://ift.tt/2CCQtKx

Al-based composites reinforced with AlB2, AlN and BN phases: Experimental and theoretical studies

Publication date: 5 March 2018
Source:Materials & Design, Volume 141
Author(s): Alexander E. Steinman, Shakti Corthay, Konstantin L. Firestein, Dmitry G. Kvashnin, Andrey M. Kovalskii, Andrei T. Matveev, Pavel B. Sorokin, Dmitri V. Golberg, Dmitry V. Shtansky
The influence of reinforcing AlN, AlB2 and BN phases, either individually or in combination, on the mechanical properties of Al-based composites fabricated via reactive ball milling of Al/BN, Al/B, and Al/Li3N powder mixtures, followed by their spark plasma sintering (SPS) was studied. An increase in tensile strength by 135% (25°C) and 185% (500°C) compared to pure Al was achieved in the Al/BN composites where BN, AlN, and AlB2 phases simultaneously formed. Density functional theory (DFT) calculations of the interface strength between Al and formed phases supported the experimental data. The obtained results demonstrated that the combination of reactive ball milling and SPS is a promising technique allowing for the formation of reinforcing phases from source materials.

Graphical abstract

http://ift.tt/2CFWRks

Design, characterisation and performance evaluation of a Peltier-driven cryo-adhesive fixture for manufacturing operations

Publication date: 5 March 2018
Source:Materials & Design, Volume 141
Author(s): S.M. O'Shaughnessy, A. Sloane, A. Kearns, G. Byrne, D. Trimble, G.E. O'Donnell
Workholding and fixturing is a critically important aspect of manufacturing that has direct implications for the quality of the manufactured component during processing as well as a direct impact on the cost of the component. The field of workholding is mature with numerous techniques employed, mostly using contact pressure, but also using magnetics and adhesives. Looking to nature for inspiration presents us with the use of ice as a mechanism for adhesion, referred to as cryo-adhesion. Cryo-adhesion offers some advantages over more traditional fixturing methods such as removing contact pressure and therefore reducing the dependence on the machining of complex, intricate bespoke fixtures. While the concept of ice adhesion is known, there is minimal research presented on the application of ice adhesion in manufacturing processes. This research reports on the development of a novel Peltier-based cryo-cooling fixture for workholding in manufacturing operations. The research provides insight into the main interactions that might be experienced in manufacturing type scenarios and presents findings on the cryo fixture's thermal and geometric characteristics, the use of the novel cryo fixture for holding various materials under tensile and shear loads, and a consideration of contact area and surface roughness on the cryo fixture performance.

Graphical abstract

http://ift.tt/2CCmqTo

Tailoring of magnesium aluminum titanate based ceramics from aluminum dross

Publication date: 5 March 2018
Source:Materials & Design, Volume 141
Author(s): Emad M.M. Ewais, Nada H.A. Besisa
Magnesium aluminum titanate (Mg0.3Al1.4Ti1.3O5 and MgAl8Ti6O25) "MAT" based ceramics were successfully prepared by reaction sintering at a temperature of 1300°C for 6h starting from aluminum dross waste and rutile ore powders. Different mixtures of dross-(0–60wt%) rutile were prepared. The obtained ceramic composites were characterized by XRD and FE-SEM. Physical and mechanical properties of MAT based ceramics were also investigated as well as the linear thermal expansion. XRD data illustrated that the solid solutions of composition Mg0.3Al1.4Ti1.3O5 and MgAl8Ti6O25 were initially formed in the specimen containing 10% rutile (R). Afterward, their amount increased with further addition of rutile up to 60%. The best values of densification parameters (≈2.76g/cm³ bulk density and ≈12.46% apparent porosity) were recorded for specimen containing 20% rutile. In contrast, 50% and 60% R added samples, which are mainly composed of Mg0.3Al1.4Ti1.3O5, MgAl8Ti6O25 and traces of TiO2 exhibited density of 2.31g/cm³ and 2.5g/cm³, respectively. Moreover, the obtained samples present thermal stability even at high temperatures. No decomposition was observed over a range of temperature of RT-1200°C. In addition, the TECs of the obtained samples have lower values than those of AT ceramics. As a consequence, the solid state sintering of aluminum dross waste and rutile ore can be considered as a promising way to produce a new advanced ceramic material based on MAT. Also, using this waste has two intrinsic impacts. One over the nature by reusing this waste and the second on production cost.

Graphical abstract

http://ift.tt/2CBldf7