Background: Retinal and optic disc perfusion in nonarteritic anterior ischemic optic neuropathy (NAION) is incompletely understood. Our aim was to investigate the characteristics of the microvascular structures at the peripapillary area and optic disc, and their associations with retinal structure and function in patients with NAION. Methods: We conducted a prospective, observational case series study. Thirty-four eyes, consisting of 15 NAION eyes and 19 normal eyes, were included. Optical coherence tomography (OCT) angiography was used to measure the vessel densities in the peripapillary superficial retina and whole-depth mode inside the optic disc. Measurement of circumpapillary retinal nerve fiber layer (cpRNFL) thickness was performed using OCT. Sectorial division analysis of cpRNFL was performed by eliminating the influences of the difference in disc rotation between OCT images and OCT angiography images. Results: The vessel densities of peripapillary retina and inside the optic disc were significantly reduced in the NAION compared to the normal (both P
http://ift.tt/2hbbZZ9
Παρασκευή 16 Δεκεμβρίου 2016
Short Follow-up Bias Confounds Estimates of the "Typical" Clinical Course of Susac Syndrome.
Background: To evaluate the validity of the prevailing concept that Susac syndrome (SS), a rare microvasculopathy of the brain, retina, and inner ear, is a self-limiting disease. Methods: We performed a literature search to identify all cases of SS reported between 1973 and October 2015. If available, we determined their demographics, duration of follow-up, and the clinical course that was labeled as monocyclic or polycyclic. We attempted to determine the number of relapses and the relapse rate in patients with polycyclic disease. Results: Our literature search yielded 185 relevant publications reporting 405 cases of SS. The duration of follow-up could be determined in 247/405 cases, with a range 0.5-312 months. The mean was 41 months but the distribution was skewed, with a median of 24 months. Defining the clinical course as monocyclic or polycyclic was possible in 102 patients who were followed for greater than 24 months; 53 were identified as having a polycyclic course. Patients labeled polycyclic were followed longer than those labeled monocyclic (median 62 vs 42 months, P
http://ift.tt/2gV6Isy
http://ift.tt/2gV6Isy
Reversible Charles Bonnet Syndrome After Oculoplastic Procedures.
Individuals with Charles Bonnet syndrome (CBS) typically have severe visual loss and experience visual hallucinations yet have no psychiatric disease. Visual impairment often is due to end-stage glaucoma or macular degeneration. We report 3 cases of CBS in patients who underwent an oculoplastic surgical procedure. One patient experienced binocular visual distortion due to excessive topical ophthalmic ointment, and 2 patients experienced monocular visual impairment from patching. Visual hallucinations resolved once vision returned to baseline. We highlight the possibility of transient CBS in postoperative patients who have temporary iatrogenic vision impairment in one or both eyes. (C) 2016 by North American Neuro-Ophthalmology Society
http://ift.tt/2hbfX3W
http://ift.tt/2hbfX3W
Assessment reactivity: A randomized controlled trial of alcohol-specific measures on alcohol-related behaviors
Source:Addictive Behaviors, Volume 67
Author(s): Ellen Meier, Mary Beth Miller, Nate Lombardi, Thad Leffingwell
IntroductionCompletion of alcohol assessments influences treatment outcomes, yet little is known about the aspects of assessment that may contribute to this response. The present study is a randomized controlled trial examining how the themes of alcohol assessments (e.g., assessment of alcohol-related consequences as opposed to drinking patterns) may affect drinking behaviors.MethodsUndergraduate students (N=290, Mage=19.97, SDage=1.81, 61.7% female), reporting at least one binge drinking episode during the past month, completed one of five baseline assessment batteries that varied thematically: (a) Control (e.g., minimal drinking quantity and frequency questions), (b) Consequences (e.g., College Alcohol Problems Scale; CAPS-r), (c) Norms (e.g., Drinking Norms Rating Form), (d) Diagnostic (e.g., Alcohol Use Disorders Identification Test), and (e) Combined (all themes). Participants completed a one-month follow-up of drinking quantity/frequency and the CAPS-r.ResultsAll groups decreased their self-reported peak drinks consumed (p<0.001, ηp2=0.05) and past month frequency of drinking (p=0.002, ηp2=0.03; except for the consequences group) from baseline to follow-up. There were no between-group differences. No changes emerged in drinks per week (p=0.09, ηp2=0.01) or alcohol-related consequences (p=0.06, ηp2=0.03) from baseline to follow-up.ConclusionMinimal assessment of drinking quantity and frequency may result in assessment reactivity. Reductions in markers of risky drinking behaviors did not differ as a function of the type of assessments completed (e.g., Consequences vs Diagnostic). Continued research is needed to determine what other important variables (e.g., treatment seeking) may affect assessment reactivity.
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The impact of detergents on the tissue decellularization process: a ToF-SIMS study
Publication date: Available online 16 December 2016
Source:Acta Biomaterialia
Author(s): Lisa J White, Adam J Taylor, Denver M Faulk, Tim J Keane, Lindsey T Saldin, Janet E Reing, Ilea T Swinehart, Neill J Turner, Buddy D Ratner, Stephen F Badylak
Biologic scaffolds are derived from mammalian tissues, which must be decellularized to remove cellular antigens that would otherwise incite an adverse immune response. Although widely used clinically, the optimum balance between cell removal and the disruption of matrix architecture and surface ligand landscape remains a considerable challenge. Here we describe the use of time of flight secondary ion mass spectroscopy (ToF-SIMS) to provide sensitive, molecular specific, localized analysis of detergent decellularized biologic scaffolds. We detected residual detergent fragments, specifically from Triton X-100, sodium deoxycholate and sodium dodecyl sulphate (SDS) in decellularized scaffolds; increased SDS concentrations from 0.1% to 1.0% increased both the intensity of SDS fragments and adverse cell outcomes. We also identified cellular remnants, by detecting phosphate and phosphocholine ions in PAA and CHAPS decellularized scaffolds. The present study demonstrates ToF-SIMS is not only a powerful tool for characterization of biologic scaffold surface molecular functionality, but also enables sensitive assessment of decellularization efficacy.Statement of significanceWe report here on the use of a highly sensitive analytical technique, time of flight secondary ion mass spectroscopy (ToF-SIMS) to characterize detergent decellularized scaffolds. ToF-SIMS detected cellular remnants and residual detergent fragments; increased intensity of the detergent fragments correlated with adverse cell matrix interactions. This study demonstrates the importance of maintaining a balance between cell removal and detergent disruption of matrix architecture and matrix surface ligand landscape. This study also demonstrates the power of ToF-SIMS for the characterization of decellularized scaffolds and capability for assessment of decellularization efficacy. Future use of biologic scaffolds in clinical tissue reconstruction will benefit from the fundamental results described in this work.
Graphical abstract
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Three-dimensional Hepatic Lobule-like Tissue Constructs Using Cell-microcapsule Technology
Publication date: Available online 16 December 2016
Source:Acta Biomaterialia
Author(s): Zeyang Liu, Masaru Takeuchi, Masahiro Nakajima, Chengzhi Hu, Yasuhisa Hasegawa, Qiang Huang, Toshio Fukuda
The proper functioning of the liver and tissues containing hepatocytes greatly depends upon the intricate organization of the cells. Consequently, controlling the shape of three-dimensional (3D) cellular constructs is an important issue for in vitro applications of fabricated artificial livers. However, the precise control of tissue shape at the microscale cannot be achieved with various commonly used 3D tissue-engineered building units, such as spheroids. Here, we present the fabrication of hepatic lobule-shaped microtissue (HLSM) containing rat liver (RLC-18) cells. By using cell-microcapsule technology, RLC-18 cells were encapsulated in the core region of poly-l-lysine-alginate microcapsules. After 14 days of long-term cultivation, RLC-18 cells self-assembled into HLSM, and the cells fully occupied the microcapsule. By monitoring the cell number and albumin secretion during culture and characterizing the dimensions of the fabricated tissue, we demonstrated that the HLSM showed higher hepatic function as compared with normal cell spheroids. We also showcased the assembly of these microtissues into a 3D four-layered hepatic lobule model by a facile micromanipulation method. Our technology for fabricating 3D multilayer hepatic lobule-like, biofunctional tissue enables the precise control of tissue shape in three dimensions. Furthermore, these constructs can serve as tissue-engineered building blocks for larger organs and cellular implants in clinical treatment.
Graphical abstract
http://ift.tt/2gUVLat
A new tool to improve delivery of patient-engaged care and satisfaction in facial treatments: the Aesthetic Global Ranking Scale
Summary
Background
Physicians face the challenge of individualizing aesthetic treatments in order to match the aesthetic needs of patients with their expectations.
Objective
To review issues underlying patient satisfaction with minimally invasive aesthetic treatment and to present a patient-centric assessment tool (the Global Ranking Scale [GRS]) designed to set higher standards for patient consultation and treatment experience; ensure a comprehensive patient-centric aesthetic consultation process; and raise patient satisfaction with facial rejuvenation treatment.
Methods
A review of the design and content of the GRS and its use as part of the wider Galderma Harmony Program. Results of a small survey of clinicians who have switched to the GRS, and case studies of patients who have used the tool, are also presented.
Results
The GRS is used in ~500 clinics around the world. In a small survey, physicians who have used the GRS report that it has changed the way that patients are assessed and treated. While no patient survey was conducted, anecdotal evidence suggests that patients are satisfied with the GRS procedure and the outcomes of treatment.
Conclusions
The GRS is a new patient assessment tool that is designed as a guide for clinicians to help ensure consistency in the quality of patient assessment and consultation in their clinics offering minimally invasive facial cosmetic procedures. Qualitative research suggests that it gives patients a better chance to achieve results aligned with their needs resulting in a higher level of satisfaction with aesthetic treatments, but this needs to be confirmed in a formal patient survey.
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The role of oxidative stress in early-onset androgenetic alopecia
Abstract
Background
Androgenetic alopecia (AGA) is the most common cause of alopecia in men. In the literature, although there are in vitro studies investigating the relationship between oxidative stress and AGA, any in vivo study does not exist.
Aim
Our aim was to evaluate the oxidative stress status in male patients with early-onset AGA by measuring total oxidant levels (TOS), total antioxidant levels (TAS), and oxidative stress index (OSI).
Methods
Our study included 33 male patients with early-onset AGA and 30 healthy men between ages of 18 and 30 years old. TAS and TOS measurements were taken, and OSI was calculated.
Results
When TAS, TOS, and OSI levels were compared between patient and control groups, there was no difference for TAS level, while TOS and OSI were significantly higher in patient group. In patient group, correlation between TAS, TOS, and OSI levels and age, and disease onset age and disease duration was evaluated. Highly significant negative correlation was determined between TAS level and both age and disease duration. When TAS, TOS, and OSI levels were assessed according to AGA stage, there was no significant difference between groups, while OSI level was significantly higher in patients with family history.
Conclusions
We found increased oxidative stress in younger patients with early-onset AGA. There is need for further molecular studies on the role of oxidative stress in the etiopathogenesis of AGA. We also think that topical or systemic antioxidants can be promising in treatment of AGA, especially for young patients.
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Beware of De-intensification of Radiotherapy in Patients with p16-positive Oropharynx Cancer and Rheumatological Diseases
Publication date: Available online 16 December 2016
Source:Practical Radiation Oncology
Author(s): Bhishamjit S. Chera, Robert J. Amdur, William Mendenhall, Jose Zevallos, Neil Hayes
http://ift.tt/2haZHzH
Initial Clinical Experience of Postmastectomy Intensity Modulated Proton Therapy in Patients with Breast Expanders with Metallic Ports
Publication date: Available online 16 December 2016
Source:Practical Radiation Oncology
Author(s): Robert W. Mutter, Nicholas B. Remmes, Mohamed MH Kahila, Kathy A. Hoeft, Deanna H. Pafundi, Yan Zhang, Kimberly S. Corbin, Sean S. Park, Elizabeth S. Yan, Valerie Lemaine, Judy C. Boughey, Chris J. Beltran
PurposeThe feasibility of proton post-mastectomy radiotherapy (PMRT) in patients reconstructed with expanders has not been previously reported, limiting treatment options. We analyzed the dosimetric impact of the metallic port contained within expanders on intensity modulated proton therapy (IMPT) and report our techniques and quality control for treating patients in this setting.Methods and Materials12 patients with the same expander model underwent two-field IMPT as part of a prospective registry. All planning dosimetry was checked with an in-house graphic processing unit-based Monte-Carlo simulation. Proton ranges through the expander were validated using a sample implant. Dosimetric impact of setup metallic port position uncertainty was evaluated. Pre and post-treatment photographs were obtained and acute toxicity was graded using the Common Terminology Criteria for Adverse Events, version 4.0.ResultsNine patients had bilateral skin-sparing mastectomy with bilateral tissue expander reconstruction and three patients had unilateral skin-sparing mastectomy and reconstruction. The left side was treated in ten patients and the right side in two. Target coverage and normal tissue dose uncertainties resulting from the expander were small and clinically acceptable. The maximum physician-assessed acute radiation dermatitis was three in one patient, two in five patients and one in six patients.ConclusionsPostmastectomy IMPT in breast cancer patients with expanders is feasible and associated with favorable CTV coverage and normal tissue sparing, even when taking into account treatment uncertainties. Therefore, these patients should be eligible to participate in clinical trials studying the potential role of proton therapy in breast cancer. We caution, however, that institutions should carry out similar analyses of the physical properties and dosimetric impact of the particular expanders used in their practice prior to considering IMPT.
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Increasing faculty participation in resident education and providing cost-effective self-assessment module credit to faculty through resident generated didactics
Publication date: Available online 16 December 2016
Source:Practical Radiation Oncology
Author(s): Hyun Kim, Theresa M. Malatesta, Pramila R. Anne ', John McAna, Voichita Bar Ad, Adam P. Dicker, Robert B. Den
Purpose/Objective(s)Board certified radiation oncologists and medical physicists are required to earn self-assessment module (SAM) continuing medical education (CME) credit, which may require travel costs or usage fees. Data indicate that faculty participation in resident teaching activities is beneficial to resident education. Our hypothesis was that providing the opportunity to earn SAM credit in resident didactics would increase faculty participation in and improve resident education.Materials/MethodsSAM applications, comprised of CME certified category 1 resident didactic lectures and faculty-generated questions with respective answers, rationales and references, were submitted to the American Board of Radiology for formal review. Surveys were distributed to assess main academic campus physician (MCP), affiliate campus physician (ACP), physicist and radiation oncology resident impressions regarding the quality of the lectures. Survey responses were designed in Likert-scale format. Sign-test was performed with p<0.05 considered statistically different from neutral.ResultsFirst submission SAM approval was obtained for 9 of 9 lectures to date. A total of 52 SAM credits have been awarded to 4 physicists and 7 attending physicians. MCP and ACP attendance increased from 20% and 0%, respectively, over the 12months preceding CME/SAM lectures, to 55.6% and 20%, respectively. Survey results indicated that the change to SAM lectures increased the quality of resident lectures (p=.001), attending physician participation in resident education (p<.0001), physicist involvement in medical resident education (p=.0006) and faculty motivation to attend resident didactics (p=.004). Residents reported an increased amount of time required to prepare lectures (p=.008).ConclusionsWe are the first department, to our knowledge, to offer SAM credit to clinical faculty for participation in resident generated didactics. Offering SAM credit at resident lectures is a cost effective alternative to purchasing SAM resources, increases faculty attendance and may improve the quality of radiation oncology resident education.
http://ift.tt/2haWwIt
A KCNJ6 gene polymorphism modulates theta oscillations during reward processing
Source:International Journal of Psychophysiology
Author(s): Chella Kamarajan, Ashwini K. Pandey, David B. Chorlian, Niklas Manz, Arthur T. Stimus, Howard J. Edenberg, Leah Wetherill, Marc Schuckit, Jen-Chyong Wang, Samuel Kuperman, John Kramer, Jay A. Tischfield, Bernice Porjesz
Event related oscillations (EROs) are heritable measures of neurocognitive function that have served as useful phenotype in genetic research. A recent family genome-wide association study (GWAS) by the Collaborative Study on the Genetics of Alcoholism (COGA) found that theta EROs during visual target detection were associated at genome-wide levels with several single nucleotide polymorphisms (SNPs), including a synonymous SNP, rs702859, in the KCNJ6 gene that encodes GIRK2, a G-protein inward rectifying potassium channel that regulates excitability of neuronal networks. The present study examined the effect of the KCNJ6 SNP (rs702859), previously associated with theta ERO to targets in a visual oddball task, on theta EROs during reward processing in a monetary gambling task. The participants were 1601 adolescent and young adult offspring within the age-range of 17–25years (800 males and 801 females) from high-dense alcoholism families as well as control families of the COGA prospective study. Theta ERO power (3.5–7.5Hz, 200–500ms post-stimulus) was compared across genotype groups. ERO theta power at central and parietal regions increased as a function of the minor allele (A) dose in the genotype (AA > AG>GG) in both loss and gain conditions. These findings indicate that variations in the KCNJ6 SNP influence magnitude of theta oscillations at posterior loci during the evaluation of loss and gain, reflecting a genetic influence on neuronal circuits involved in reward-processing. Increased theta power as a function of minor allele dose suggests more efficient cognitive processing in those carrying the minor allele of the KCNJ6 SNPs. Future studies are needed to determine the implications of these genetic effects on posterior theta EROs as possible "protective" factors, or as indices of delays in brain maturation (i.e., lack of frontalization).
http://ift.tt/2gLh2OV
Socio-emotionally significant experience and children's processing of irrelevant auditory stimuli
Source:International Journal of Psychophysiology
Author(s): Alice C. Schermerhorn, John E. Bates, Aina Puce, Dennis L. Molfese
Theory and research indicate considerable influence of socio-emotionally significant experiences on children's functioning and adaptation. In the current study, we examined neurophysiological correlates of children's allocation of information processing resources to socio-emotionally significant events, specifically, simulated marital interactions. We presented 9- to 11-year-old children (n=24; 11 females) with 15 videos of interactions between two actors posing as a married couple. Task-irrelevant brief auditory probes were presented during the videos, and event-related potentials (ERPs) elicited to the auditory probes were measured. As hypothesized, exposure to higher levels of interparental conflict was associated with smaller P1, P2, and N2 ERPs to the probes. This finding is consistent with the idea that children who had been exposed to more interparental conflict attended more to the videos and diverted fewer cognitive resources to processing the probes, thereby producing smaller ERPs to the probes. In addition, smaller N2s were associated with more child behavior problems, suggesting that allocating fewer processing resources to the probes was associated with more problem behavior. Results are discussed in terms of implications of socio-emotionally significant experiences for children's processing of interpersonal interactions.
http://ift.tt/2hR1gqJ
Enhancing tolerance of rice ( Oryza sativa ) to simulated acid rain by exogenous abscisic acid
Abstract
Abscisic acid (ABA) regulates much important plant physiological and biochemical processes and induces tolerance to different stresses. Here, we studied the regulation of exogenous ABA on adaptation of rice seedlings to simulated acid rain (SAR) stress by measuring biomass dry weight, stomatal conductance, net photosynthesis rate, nutrient elements, and endogenous hormones. The application of 10 μM ABA alleviated the SAR-induced inhibition on growth, stomatal conductance, net photosynthesis rate, and decreases in contents of nutrient (K, Mg, N, and P) and hormone (auxin, gibberellins, and zeatin). Moreover, 10 μM ABA could stimulate the Ca content as signaling molecules under SAR stress. Contrarily, the application of 100 μM ABA aggravated the SAR-induced inhibition on growth, stomatal conductance, net photosynthesis rate, and contents of nutrient and hormone. The results got after a 5-day recovery (without SAR) show that exogenous 10 μM ABA can promote self-restoration process in rice whereas 100 μM ABA hindered the restoration by increasing deficiency of nutrients and disturbing the balance of hormones. These results confirmed that exogenous ABA at proper concentration could enhance the tolerance of rice to SAR stress.
http://ift.tt/2hYJ36C
Exploring river pollution based on sediment analysis in the Upper Tisza region (Hungary)
Abstract
We assessed contamination in the Upper Tisza region (Hungary, Central Europe), analyzing the elemental concentrations in sediment cores of oxbows. Our hypothesis was that the metal contamination which occurred in the year 2000 and which came from the mining area in Transylvania (Romania) may be detected even 15 years after the contamination, based on the vertical profile of sediment cores. Sediment cores were collected from five oxbows, and the following elements were measured with microwave plasma-atomic emission spectrometry (MP-AES): Cu, Cr, Ba, Fe, Mn, Pb, Sr, and Zn. Among the oxbows studied, there was one protected oxbow, three were used for fishing, and one was contaminated with sewage. Our results indicated that the year of contamination is still observable in the vertical profile of the sediment cores. The pollution index (PI) was used to characterize the sediment enrichment of metal elements in the sediment cores. In the case of Cu, Pb, and Zn, the contamination which originated in the year 2000 was detected in the layers of the sediment cores. The contamination levels of Cu, Pb, and Zn were high or moderate in the studied oxbows. All oxbows were moderately contaminated by Mn, while a moderate level of contamination was found for Fe in the protected oxbow, one fishing oxbow, and the sewage-contaminated oxbow. In the fishing oxbows, a low level of contamination was found for Fe. The contamination level of Sr was low in the protected oxbow and in the two fishing oxbows, while in one of the fishing oxbows and in the sewage-contaminated oxbow, a moderate level of Sr contamination was found. The pollution index scores indicated that the contamination level for Ba and Cr was low in the sediment cores of the oxbows studied. Our results indicated that the contamination of the Tisza River from the mining area in Northern Romania has been continuous and is still ongoing.
http://ift.tt/2hYKQZr
Further understanding on the mechanism of alkyl ketene dimer sizing on the causticized calcium carbonate filled paper and its improvements
Abstract
Causticized calcium carbonate (CCC), a solid waste derived from kraft black recovery process, can be used as an alternative for the conventional precipitated calcium carbonate (PCC). However, the application of the CCC has been limited due to its low sizing efficiency in its filled paper. In this study, the characteristics of the CCC were studied aiming to improve the alkyl ketene dimer (AKD) sizing performances of the CCC filled papers, and the results were compared with those from PCC filled papers. The results showed that the CCC had higher pore structure, higher specific surface area, and more negative charge density than the PCC, thus leading to a higher cationic AKD adsorption onto the CCC filler. The lower AKD sizing efficiency in the CCC filled paper can be explained by the combination of higher AKD adsorption and migration, both of which resulted in preferred AKD adsorption onto/into the CCC fillers, rather than the cellulose fibers. Based on the above, the prior addition of polyamide-polyamine epichlorhydrin (PAE) resin to the CCC filler system was proposed to remedy the related issues, thus improving the sizing efficiency.
http://ift.tt/2gV3DH8
Environmental investigation for the presence of Vibrio species following a case of severe gastroenteritis in a touristic island
Abstract
Global changes have caused a worldwide increase in reports of Vibrio-associated diseases with ecosystem-wide impacts on humans and marine animals. In Europe, higher prevalence of human infections followed regional climatic trends with outbreaks occurring during episodes of unusually warm weather. Similar patterns were also observed in Vibrio-associated diseases affecting marine organisms such as fish, bivalves, and corals. Following a possible human case of infection due to V. cholerae in the island of Kos (eastern Aegean, Greece), environmental samples were collected and tested for the presence of Vibrio species. Using chromogenic agar and MALDI-TOF MS, V. parahaemolyticus, V. vulnificus V. furnisii, V. alginolyticus, and V. fluvialis were isolated and/or identified. The presence of V. cholerae was established by PCR-sequencing analysis only. Following the susceptibility testing of the Vibrio isolates, only one, V. furnisii, showed intermediate resistance to ciprofloxacin. The rest of the isolates were susceptible to all antibiotics tested. The presence of Vibrio species in aquatic samples reveals potential dangers due to exposure to contaminated seawaters.
http://ift.tt/2hYQ6vW
Effective characterization of Salmonella Enteritidis by most probable number (MPN) followed by multiplex polymerase chain reaction (PCR) methods
Abstract
Nontyphoidal Salmonella (NTS) is a relevant pathogen involved in gastroenteritis outbreaks worldwide. In this study, we determined the capacity to combine the most probable number (MPN) and multiplex polymerase chain reaction (PCR) methods to characterize the most important Salmonella serotypes in raw sewage. A total of 499 isolates were recovered from 27 raw sewage samples and screened using two previously described multiplex PCR methods. From those, 123 isolates were selected based on PCR banding pattern—identical or similar to Salmonella Enteritidis and Salmonella Typhimurium—and submitted to conventional serotyping. Results showed that both PCR assays correctly serotyped Salmonella Enteritidis, however, they presented ambiguous results for Salmonella Typhimurium identification. These data highlight that MPN and multiplex PCR can be useful methods to describe microbial quality in raw sewage and suggest two new PCR patterns for Salmonella Enteritidis identification.
http://ift.tt/2gV6qAn
Reducing N losses through surface runoff from rice-wheat rotation by improving fertilizer management
Abstract
To better understand N runoff losses from rice-wheat rotation and demonstrate the effectiveness of improved fertilizer management in reducing N runoff losses, a field study was conducted for three consecutive rice-wheat rotations. Nitrogen losses through surface runoff were measured for five treatments, including CK without N application, C200, C300 simulating the conventional practices, CO200, and CO300. Optimum N rate was applied for C200 and CO200, and 30% of chemical fertilizer was substituted with organic fertilizer for CO200 and CO300 with respect to C200 and C300, respectively. Rice season had higher runoff coefficients than wheat season. Approximately 52% of total N was lost as NH4+-N in rice season, ranging from 21 to 83%, and in wheat season, the proportion of NO3−-N in total N averaged 53% with a variation from 38 to 67%. The N treatments lost less total N in rice season (1.67–10.7 kg N ha−1) than in wheat season (1.72–17.1 kg N ha−1). These suggested that a key to controlling N runoff losses from rice-wheat rotation was to limit NO3−-N accumulation in wheat season. In both seasons, N runoff losses for C200 and CO300 were lower than those for C300. CO200 better cut N losses than C200 and CO300, with 64 and 57% less N in rice and wheat seasons than C300, respectively. Compared with the conventional practices, optimum N inputs integrated with co-application of organic and chemical fertilizers could reduce N runoff losses with a better N balance under rice-wheat rotation.
http://ift.tt/2hYSkeN
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Publication date: September 2017 Source: Free Radical Biology and Medicine, Volume 110 Author(s): Lucía Fernández-del-Río, Anish Nag, Elen...
