Antimony isotopes as indicators of redox reactions in aqueous systems: fractionation during Sb(V) reduction by sulfide and isotope exchange kinetics between dissolved Sb(III) and Sb(V)

Antimony (Sb) has a history of being overlooked as an aqueous contaminant. The widespread commercial use of Sb has caused scientists to realize the importance of studying the fate and transport of Sb. For other contaminant elements, stable isotopic ratio measurements have been useful for source tracing and detection of environmentally critical chemical reactions (e.g., Wiederhold 2015). We seek to develop Sb isotopic ratios as tools for detecting and quantifying Sb in the environment. Currently, processes that generate shifts in 123Sb/121Sb are not well studied, though they can be inferred from theory and the isotopic systematics of other elements. To provide a more precise understanding of the drivers of Sb isotope variation, the magnitude of isotopic fractionation for individual reactions must be determined. In this study, we determine the magnitude of isotopic fractionation in environmentally relevant reactions. We use anion exchange resin and hydride generation MC-ICP-MS methods to obtain precise measurements of 123Sb/121Sb. The anion exchange method is also effective for separating Sb(III) from Sb(V). First, we find that isotopic exchange between aqueous Sb(V) and Sb(III) at higher than natural concentrations (3 mM Sb) is negligible over a timescale of 6 weeks. At the lower concentrations of natural systems, exchange is likely to be much slower. Accordingly, we conclude that kinetic isotope effects that occur during Sb redox reactions are not overprinted by isotopic exchange, which would drive coexisting Sb(III) and Sb(V) toward isotopic equilibrium. Second, we quantified isotopic fractionation during reduction of 8.2 μM aqueous Sb(V) by sulfide to form amorphous Sb2S3. The data mostly conform to a Rayleigh distillation model, with 5 out of 11 data points deviating from the model slightly more than the measurement uncertainty. During experimentation it was found that the dissolved portion contained about 75% Sb(V) and 25% Sb(III). The best-fit model corresponds to an isotopic fractionation factor of 0.9986; Sb2S3 product was lower in 123Sb/121Sb, relative to the dissolved portion. This is a larger magnitude of 123Sb/121Sb shift during Sb(V) reduction than observed by Rouxel et. al. (2003)

Assessing Tolerance to Heavy-Metal Stress in Arabidopsis thaliana Seedlings

The deposited book chapter is a post-print version and has been submitted to peer review.The deposited book chapter version contains attached the supplementary materials within the pdf.This publication hasn't any creative commons license associated.The deposited book chapter is part of the book series: "Environmental Responses in Plants: Methods and Protocols" (pp.197-208) published by Springer.Heavy-metal soil contamination is one of the major abiotic stress factors that, by negatively affecting plant growth and development, severely limit agricultural productivity worldwide. Plants have evolved various tolerance and detoxification strategies in order to cope with heavy-metal toxicity while ensuring adequate supply of essential micronutrients at the whole-plant as well as cellular levels. Genetic studies in the model plant Arabidopsis thaliana have been instrumental in elucidating such mechanisms. The root assay constitutes a very powerful and simple method to assess heavy-metal stress tolerance in Arabidopsis seedlings. It allows the simultaneous determination of all the standard growth parameters affected by heavy-metal stress (primary root elongation, lateral root development, shoot biomass, and chlorophyll content) in a single experiment. Additionally, this protocol emphasizes the tips and tricks that become particularly useful when quantifying subtle alterations in tolerance to a given heavy-metal stress, when simultaneously pursuing a large number of plant lines, or when testing sensitivity to a wide range of heavy metals for a single line.Fundação para a Ciência e a Tecnologia grants: (EXPL/AGR-PRO/1013/2013, SFRH/BPD/44640/2008); GREEN-it "Bioresources for Sustainability": (UID/Multi/04551/2013).info:eu-repo/semantics/publishedVersio

Label-free chemically specific imaging in planta with stimulated Raman scattering microscopy.

The growing world population puts ever-increasing demands on the agricultural and agrochemical industries to increase agricultural yields. This can only be achieved by investing in fundamental plant and agrochemical research and in the development of improved analytical tools to support research in these areas. There is currently a lack of analytical tools that provide noninvasive structural and chemical analysis of plant tissues at the cellular scale. Imaging techniques such as coherent anti-Stokes Raman scattering (CARS) and stimulated Raman scattering (SRS) microscopy provide label-free chemically specific image contrast based on vibrational spectroscopy. Over the past decade, these techniques have been shown to offer clear advantages for a vast range of biomedical research applications. The intrinsic vibrational contrast provides label-free quantitative functional analysis, it does not suffer from photobleaching, and it allows near real-time imaging in 3D with submicrometer spatial resolution. However, due to the susceptibility of current detection schemes to optical absorption and fluorescence from pigments (such as chlorophyll), the plant science and agrochemical research communities have not been able to benefit from these techniques and their application in plant research has remained virtually unexplored. In this paper, we explore the effect of chlorophyll fluorescence and absorption in CARS and SRS microscopy. We show that with the latter it is possible to use phase-sensitive detection to separate the vibrational signal from the (electronic) absorption processes. Finally, we demonstrate the potential of SRS for a range of in planta applications by presenting in situ chemical analysis of plant cell wall components, epicuticular waxes, and the deposition of agrochemical formulations onto the leaf surface

Incidence, patterns and severity of reported unintentional injuries in Pakistan for persons five years and older: results of the National Health Survey of Pakistan 1990–94

<p>Abstract</p> <p>Background</p> <p>National level estimates of injuries are not readily available for developing countries. This study estimated the annual incidence, patterns and severity of unintentional injuries among persons over five years of age in Pakistan.</p> <p>Methods</p> <p>National Health Survey of Pakistan (NHSP 1990–94) is a nationally representative survey of the household. Through a two-stage stratified design, 18, 315 persons over 5 years of age were interviewed to estimate the overall annual incidence, patterns and severity of unintentional injuries for males and females in urban and rural areas over the preceding one year. Weighted estimates were computed adjusting for complex survey design using <it>surveyfreq </it>and <it>surveylogistic </it>option of SAS 9.1 software.</p> <p>Results</p> <p>The overall annual incidence of all unintentional injuries was 45.9 (CI: 39.3–52.5) per 1000 per year; 59.2 (CI: 49.2–69.2) and 33.2 (CI: 27.0–39.4) per 1000 per year among males and females over five years of age, respectively. An estimated 6.16 million unintentional injuries occur in Pakistan annually among persons over five years of age. Urban and rural injuries were 55.9 (95% CI: 48.1–63.7) and 41.2 (95% CI: 32.2–50.0) per 1000 per year, respectively. The annual incidence of injuries due to falls were 22.2 (95% CI: 18.0–26.4), poisoning 3.3 (95%CI: 0.5–6.1) and burn was 1.5 (95%CI: 0.9–2.1) per 1000 per year. The majority of injuries occurred at home 19.2 (95%CI: 16.0–22.4) or on the roads 17.0 (95%CI: 13.8–20.2). Road traffic/street, school and urban injuries were more likely to result in handicap.</p> <p>Conclusion</p> <p>There is high burden of unintentional injuries among persons over five years of age in Pakistan. These results are useful to plan further studies and prioritizing prevention programs on injuries nationally and other developing countries with similar situation.</p

NUCLEAR MERCHANT SHIP REACTOR PROJECT. EXTENDED ZERO POWER TESTS NS SAVANNAH CORE I. Final Report

Experiments were performed on the NS Savannah Service Core I to supply irformation on future shipboard operation of the Nuclear Merchant Ship Reactor. Testing of instrumentation equipment was satisfactory. Correction factors for shipboard use were determined. Fast neutron flux, neutron fiux distribution, and stuck control rod studies were carried out successfully, as was a three- dimesional calculation to match two critical rod patterns. (auth

A Common CNR1 (Cannabinoid Receptor 1) Haplotype Attenuates the Decrease in HDL Cholesterol That Typically Accompanies Weight Gain

We have previously shown that genetic variability in CNR1 is associated with low HDL dyslipidemia in a multigenerational obesity study cohort of Northern European descent (209 families, median  = 10 individuals per pedigree). In order to assess the impact of CNR1 variability on the development of dyslipidemia in the community, we genotyped this locus in all subjects with class III obesity (body mass index >40 kg/m2) participating in a population-based biobank of similar ancestry. Twenty-two haplotype tagging SNPs, capturing the entire CNR1 gene locus plus 15 kb upstream and 5 kb downstream, were genotyped and tested for association with clinical lipid data. This biobank contains data from 645 morbidly obese study subjects. In these subjects, a common CNR1 haplotype (H3, frequency 21.1%) is associated with fasting TG and HDL cholesterol levels (p = 0.031 for logTG; p = 0.038 for HDL-C; p = 0.00376 for log[TG/HDL-C]). The strength of this relationship increases when the data are adjusted for age, gender, body mass index, diet and physical activity. Mean TG levels were 160±70, 155±70, and 120±60 mg/dL for subjects with 0, 1, and 2 copies of the H3 haplotype. Mean HDL-C levels were 45±10, 47±10, and 48±9 mg/dL, respectively. The H3 CNR1 haplotype appears to exert a protective effect against development of obesity-related dyslipidemia