Degradation of the earthy and musty odorant 2,4,6-tricholoroanisole by persulfate activated with iron of different valences

Abstract

2,4,6-Trichloroanisole (TCA) is an odorous compound that is often detected in tap water and is difficult to be removed via water treatment. In this study, the transformation efficiency of TCA in the presence of persulfate (PS) activated by iron (Fe²⁺, Fe⁰, and Fe³⁺) was investigated for the first time. The effects of the activator dosage, oxidant dosage, pH, dosing method, chelating agents, humic acid, and temperature were evaluated. The degradation rate of TCA increased with increasing PS dosages (0.12–0.48 mM) and initial Fe²⁺ concentrations (0.12–0.96 mM), while it decreased with higher Fe²⁺ concentrations. Fe²⁺/PS and Fe⁰/PS systems achieved their best TCA removal efficiency at pH 7 and 2.5, respectively. According to the results of electron paramagnetic resonance (EPR), the contribution of SO₄⁻• to TCA degradation was much higher than that of •OH. Gradual addition of Fe²⁺ improved TCA degradation compared to single addition. Citric acid (CA) promoted TCA degradation under Fe²⁺/PS at the beginning of the reaction, but inhibited it after 10 min. Ethylenediaminetetraacetic acid (EDTA) improved the TCA removal rate with an EDTA/Fe²⁺ molar ratio of 0.5:1, while it decreased it at higher EDTA/Fe²⁺ molar ratios. Oxalic acid (OA) negatively affected TCA degradation with increasing OA/Fe²⁺ molar ratios. Among all of the chelating agents, only CA increased TCA degradation by Fe⁰/PS. Humic acid promoted TCA degradation by Fe²⁺/PS at the proper dosage (1 mg/L). Under our specific conditions and over the temperature ranging from 10 to 25 °C, no change was observed in the reaction kinetics. It was found that 2,4,6-trichlorophenol (TCP) was the only detected oxidation product. The presence of an Fe²⁺-Fe³⁺ redox cycle in iron-activated PS systems was confirmed by TCA degradation under the Fe³⁺/PS system.

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A novel process for CO 2 capture by using sodium metaborate. Part I: effects of calcination

Abstract

This paper presents a comprehensive study on the carbonation of sodium metaborate (NaBO₂) and the synthesis of high added value chemicals via NaBO₂ and carbon dioxide (CO₂). Carbon dioxide (CO₂) is a greenhouse gas and NaBO₂ is a by-product of sodium borohydride (NaBH₄) hydrolysis reaction to produce H₂. Therefore their transformation into commercial chemicals is quite important in order to provide a mutual benefit to global warming issue and hydrogen economy. In the presented study, reaction parameters such as hydration factor, furnace type, calcination temperature, and environment are investigated at different levels and optimized. The effects of those key parameters on CO₂ fixation yield are discussed. It is found that 400 °C is a key temperature for dehydration and reaction steps. Both dehydrated NaBO₂ is obtained and maximum carbonation conversion is reached at 400 °C. Moreover, at relatively low temperatures (below 400 °C), a new reaction pathway is proposed and proved by thermodynamic calculations. Structural properties of NaBO₂ are exhibited differences regard to thermal exposure and the conversion is strictly related to the structural properties.

http://ift.tt/2zf2bdp

Silica nanoparticle exposure inducing granulosa cell apoptosis and follicular atresia in female Balb/c mice

Abstract

Given that the effects of ultrafine fractions (< 0.1 μm) on reproductive diseases are gaining attention, this study aimed to explore the influence of silica nanoparticle (SiNP)-induced female reproductive dysfunction. In this study, 80 female mice were randomly divided into four groups including a control group and three concentrations of SiNP groups (7, 21, 35 mg/kg). Mice were exposed to the vehicle control and silica nanoparticles by tracheal perfusion every 3 days a total of five times in 15 days. Then, half of the mice in each group were sacrificed on 15 and 30 days after the first dose, respectively. Our findings indicated that SiNPs can result in ovarian damage, cause an imbalance of sex hormones, increase the number of atretic and primary follicles, and induce oxidative stress and DNA strand breaks in ovary by day 15. The protein expressions of ATM, CHK-2, P53, E2F1, P73, BAX, Caspase-9, and Caspase-3 were significantly increased, while expressions of RAD51 were down-regulated after SiNP exposure by days 15. Estradiol increased, while progesterone increased in low dose and decreased in high dose after SiNP exposure by 15 days. However, these changes were recovered by 30 days. The results suggest that SiNPs can cause reversible damage to follicles in mice. SiNPs could primarily cause DNA damage and DNA damage response through oxidative stress, while DNA damage repair failure because of severe DNA damage activated the mitochondrial apoptosis pathway and therefore resulted in apoptosis of granulosa cell. In addition, the disorder of reproductive endocrine function caused by SiNPs could be another reason for SiNP-induced reproductive dysfunction in mice. These events in turn induce the follicles to undergo atresia.

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Publication date: February 2018
Source:Neuroimaging Clinics of North America, Volume 28, Issue 1





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Source:Neuroimaging Clinics of North America, Volume 28, Issue 1





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Publication date: February 2018
Source:Neuroimaging Clinics of North America, Volume 28, Issue 1





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Contents

Publication date: February 2018
Source:Neuroimaging Clinics of North America, Volume 28, Issue 1





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Imaging of Brain Concussion

Publication date: February 2018
Source:Neuroimaging Clinics of North America, Volume 28, Issue 1
Author(s): Eliana Bonfante, Roy Riascos




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Imaging of Brain Concussion

Publication date: February 2018
Source:Neuroimaging Clinics of North America, Volume 28, Issue 1
Author(s): Suresh K. Mukherji




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Imaging of Cerebral Concussion and Chronic Traumatic Encephalopathy

Publication date: February 2018
Source:Neuroimaging Clinics of North America, Volume 28, Issue 1
Author(s): Eliana Bonfante, Roy Riascos




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Definition of Traumatic Brain Injury, Neurosurgery, Trauma Orthopedics, Neuroimaging, Psychology, and Psychiatry in Mild Traumatic Brain Injury

Publication date: February 2018
Source:Neuroimaging Clinics of North America, Volume 28, Issue 1
Author(s): Mubashir Pervez, Ryan S. Kitagawa, Tiffany R. Chang

Teaser

Traumatic brain injury (TBI) disrupts the normal function of the brain. This condition can adversely affect a person's quality of life with cognitive, behavioral, emotional, and physical symptoms that limit interpersonal, social, and occupational functioning. Although many systems exist, the simplest classification includes mild, moderate, and severe TBI depending on the nature of injury and the impact on the patient's clinical status. Patients with TBI require prompt evaluation and multidisciplinary management. Aside from the type and severity of the TBI, recovery is influenced by individual patient characteristics, social and environmental factors, and access to medical and rehabilitation services.


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Conventional Computed Tomography and Magnetic Resonance in Brain Concussion

Publication date: February 2018
Source:Neuroimaging Clinics of North America, Volume 28, Issue 1
Author(s): Juan Nicolas Useche, Sonia Bermudez

Teaser

Conventional neuroimaging is still the mainstay in the assessment of the acute, follow-up, and chronic settings of concussion and mild traumatic brain injury (mTBI). Computed tomography (CT) is preferred for the initial assessment of acute mTBI, repeat evaluation in acute mTBI with neurologic deterioration, and cautious use in children with mTBI. Clinical rules have been developed to identify pediatric and adult patients with mTBI who can safely forego CT. Magnetic resonance (MR) imaging is mostly used in patients with acute mTBI when initial or follow-up CT is normal and there are persistent neurologic findings and in subacute or chronic mTBI.


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Multimodal Advanced Imaging for Concussion

Publication date: February 2018
Source:Neuroimaging Clinics of North America, Volume 28, Issue 1
Author(s): Khader M. Hasan, Zafer Keser, Paul E. Schulz, Elisabeth A. Wilde

Teaser

In the United States alone, 1.6 to 3.8 million people have sports-related concussions yearly. The patho-mechanisms of concussions may not be directly measured by conventional neuroimaging; advanced models may be needed to address the shortcomings of the current clinical protocols. Multimodal advanced imaging may provide more accurate diagnosis and predict the clinical course of concussion, assessing the efficacy of existing and emerging multifaceted therapies. In this article, the authors present an overview and pictorial display of conventional and advanced multimodal MR imaging methods that have been applied to identify the brain structures affected in traumatic brain injuries.


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Imaging of Concussion in Young Athletes

Publication date: February 2018
Source:Neuroimaging Clinics of North America, Volume 28, Issue 1
Author(s): Jeffrey P. Guenette, Martha E. Shenton, Inga K. Koerte

Teaser

Conventional neuroimaging examinations are typically normal in concussed young athletes. A current focus of research is the characterization of subtle abnormalities after concussion using advanced neuroimaging techniques. These techniques have the potential to identify biomarkers of concussion. In the future, such biomarkers will likely provide important clinical information regarding the appropriate time interval before return to play, as well as the risk for prolonged postconcussive symptoms and long-term cognitive impairment. This article discusses results from advanced imaging techniques and emphasizes imaging modalities that will likely become available in the near future for the clinical evaluation of concussed young athletes.


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Perfusion Imaging in Acute Traumatic Brain Injury

Publication date: February 2018
Source:Neuroimaging Clinics of North America, Volume 28, Issue 1
Author(s): David B. Douglas, Ruchir Chaudhari, Jason M. Zhao, James Gullo, Jared Kirkland, Pamela K. Douglas, Ely Wolin, James Walroth, Max Wintermark

Teaser

Traumatic brain injury (TBI) is a significant problem worldwide and neuroimaging plays a critical role in diagnosis and management. Recently, perfusion neuroimaging techniques have been explored in TBI to determine and characterize potential perfusion neuroimaging biomarkers to aid in diagnosis, treatment, and prognosis. In this article, computed tomography (CT) bolus perfusion, MR imaging bolus perfusion, MR imaging arterial spin labeling perfusion, and xenon CT are reviewed with a focus on their applications in acute TBI. Future research directions are also discussed.


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PET and Single-Photon Emission Computed Tomography in Brain Concussion

Publication date: February 2018
Source:Neuroimaging Clinics of North America, Volume 28, Issue 1
Author(s): Cyrus A. Raji, Theodore A. Henderson

Teaser

This article offers an overview of the application of PET and single photon emission computed tomography brain imaging to concussion, a type of mild traumatic brain injury and traumatic brain injury, in general. The article reviews the application of these neuronuclear imaging modalities in cross-sectional and longitudinal studies. Additionally, this article frames the current literature with an overview of the basic physics and radiation exposure risks of each modality.


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Imaging the Role of Myelin in Concussion

Publication date: February 2018
Source:Neuroimaging Clinics of North America, Volume 28, Issue 1
Author(s): Alexander Mark Weber, Carlos Torres, Alexander Rauscher

Teaser

Myelin water imaging (MWI) provides mild traumatic brain injury (mTBI) researchers with a specific myelin biomarker and helps to further elucidate microstructural and microarchitectural changes of white matter after mTBI. Improvement of scanner hardware and software with the implementation of MWI across scanner platforms will likely result in increased research regarding the role of myelin in traumatic brain injury (TBI). Future research should include detailed investigation of myelin between 2 weeks and 2 months after injury, the use of MWI in moderate and severe TBI, and investigation of the role of myelin in chronic TBI.


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Susceptibility-Weighted Imaging and Magnetic Resonance Spectroscopy in Concussion

Publication date: February 2018
Source:Neuroimaging Clinics of North America, Volume 28, Issue 1
Author(s): Ivan I. Kirov, Christopher T. Whitlow, Carlos Zamora

Teaser

Although susceptibility-weighted imaging (SWI) studies have suggested an increased number of microhemorrhages in concussion, most show no significant differences compared with controls. There have been mixed results on using SWI to predict neurologic outcomes. Drawbacks include inability to time microhemorrhages and difficulty in attributing them to the concussion. Magnetic resonance spectroscopy (MRS) in concussion can identify metabolic abnormalities, with many studies showing correlations with clinical outcome. Applications in individual patients are impeded by conflicting data and lack of consensus on an optimal protocol. Therefore, currently MRS has most utility in group-level comparisons designed to reveal the pathophysiology of concussion.


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Functional MR Imaging: Blood Oxygen Level–Dependent and Resting State Techniques in Mild Traumatic Brain Injury

Publication date: February 2018
Source:Neuroimaging Clinics of North America, Volume 28, Issue 1
Author(s): Scott Rosenthal, Matthew Gray, Hudaisa Fatima, Haris I. Sair, Christopher T. Whitlow

Teaser

This article discusses mild traumatic brain injury (mTBI)-associated effects on brain functional connectivity assessed via resting-state functional MR (fMR) imaging. Several studies have reported acute post-injury default mode network hyperconnectivity, followed by a period of decreased connectivity before later connectivity normalization in some patients. Other studies have reported mTBI associated effects on connectivity that remain evident for up to 5-years or more. Discordance in the published literature regarding the direction of network connectivity changes (eg, increased versus decreased connectivity) may reflect differences in timing of data collection post-injury, as well as the need to standardize MR imaging acquisition protocols and processing methods.


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