High Se Research Articles

Linking circular economy model and green supply chain practices to shape environmental performance: case of Vietnam.

The circular economy (SE) is the foremost element for environmental improvement that reduces wastage and enhances production. This aspect requires the focus of new researchers and experienced policymakers. Hence, the current research examines the impact of SE practices such as internal environmental management (IEM), eco-design, and internal recovery on the SE targeted performance, such as environmental performance in Vietnam. The research also investigates the moderating role of environmental-oriented supply chain (SC) practices such as green purchases among IEM, eco-design, internal recovery, and environmental performance in Vietnam. The research collected the data from the respondents using survey questionnaires. The research also investigates the association among variables using smart-PLS. The outcomes revealed that the IEM, eco-design, and internal recovery are positively associated with environmental performance. The outcomes also exposed that the green purchases significantly moderates among IEM, eco-design, internal recovery, and environmental performance. The research guides the regulators in establishing regulations related to achieve the high SE targeted performance, such as environmental performance using circular economy practices such as IEM, eco-design, and internal recovery.

Liquid metal assisted fabrication of MXene-based films: Toward superior electromagnetic interference shielding and thermal management

The development of thin and flexible films that possess both electromagnetic interference (EMI) shielding and thermal management capabilities has always been an intriguing pursuit, but itisnevertheless a crucialproblemtoaddress. Inspired by the deformability of liquid metal (LM) and film forming capacity of MXene, here we present a series of ternary compositing films prepared via cellulose nanofiber (CNF) assisted vacuum filtration technology. Originating from the highly conductive LM/MXene network, the MLMC film presents a maximum EMI shielding effectiness (EMI SE) of 78 dB at a tiny thickness of 45 μm, together with a high specific EMI SE of 3046 dB mm−1. Meanwhile, these compositing films also deliver excellent flexibility and mechanical reliability, showing no obvious decline in EMI shielding performance even after 1000 bending and 500 folding cycles, respectively. Moreover, notable anisotropic thermal conductive property was successfully achieved, allowing for a highly desirable in-plane thermal conductivity of 7.8 W m−1 K−1. This accomplishment also yielded an exceptional electro-thermal conversion capacity, enabling efficient low-voltage (3 V) heating capabilities. These captivating features are expected to greatly drive the widespread adoption of LM-based films in future flexible electronic and wearable technologies.

A pilot survey of selenium status and its geospatial variation among children and women in three rural districts of Zimbabwe.

Selenium (Se) deficiency is increasingly recognized as a public health problem in sub-Saharan Africa. The current cross-sectional study assessed the prevalence and geospatial patterns of Se deficiency among children aged 6-59 months (n = 741) and women of 15-49 years old (n = 831) selected by simple random sampling in rural Zimbabwe (Murewa, Shamva, and Mutasa districts). Venous blood samples were collected and stored according to World Health Organization guidelines. Plasma Se concentration was determined by inductively coupled plasma-mass spectrometry. Median, Q1, and Q3 plasma Se concentrations were 61.2, 48.7, and 73.3 μg/L for women and 40.5, 31.3, and 49.5 μg/L for children, respectively. Low plasma Se concentrations (9.41 μg/L in children and 10.20 μg/L in women) indicative of severe Se deficiency risk was observed. Overall, 94.6% of children and 69.8% of women had sub-optimal Se status defined by plasma Se concentrations of <64.8 μg/L and <70 μg/L, respectively. High and widespread Se deficiency among women and children in the three districts is of public health concern and might be prevalent in other rural districts in Zimbabwe. Geostatistical analysis by conditional kriging showed a high risk of Se deficiency and that the Se status in women and children in Murewa, Shamva, and Mutasa districts was driven by short-range variations of up to ⁓12 km. Selenium status was homogenous within each district. However, there was substantial inter-district variation, indicative of marked spatial patterns if the sampling area is scaled up. A nationwide survey that explores the extent and spatial distribution of Se deficiency is warranted.

Selenium Ameliorated Oxidized Fish Oil-Induced Lipotoxicity via the Inhibition of Mitochondrial Oxidative Stress, Remodeling of Usp4-Mediated Deubiquitination, and Stabilization of Pparα.

Aims: Studies demonstrated that oxidized fish oil (OFO) promoted oxidative stress and induced mitochondrial dysfunction and lipotoxicity, which attenuated beneficial effects of fish oil supplements in the treatment of nonalcoholic fatty liver disease (NAFLD). The current study was performed on yellow catfish, a good model to study NAFLD, and its hepatocytes to explore whether selenium (Se) could alleviate OFO-induced lipotoxicity via the inhibition of oxidative stress and determine its potential mechanism. Results: The analysis of triglycerides content, oxidative stress parameters, and histological and transmission electronic microscopy observation showed that high dietary Se supplementation alleviated OFO-induced lipotoxicity, oxidative stress, and mitochondrial injury and dysfunction. RNA-sequencing and immunoblotting analysis indicated that high dietary Se reduced OFO-induced decline of peroxisome-proliferator-activated receptor alpha (Pparα) and ubiquitin-specific protease 4 (Usp4) protein expression. High Se supplementation also alleviated OFO-induced reduction of thioredoxin reductase 2 (txnrd2) messenger RNA (mRNA) expression level and activity. The txnrd2 knockdown experiments revealed that txnrd2 mediated Se- and oxidized eicosapentaenoic acid (oxEPA)-induced changes of mitochondrial reactive oxygen species (mtROS) and further altered Usp4 mediated-deubiquitination and stabilization of Pparα, which, in turn, modulated mitochondrial fatty acid β-oxidation and metabolism. Mechanistically, Usp4 deubiquitinated Pparα and ubiquitin-proteasome-mediated Pparα degradation contributed to oxidative stress-induced mitochondrial dysfunction. Innovation: These findings uncovered a previously unknown mechanism by which Se and OFO interacted to affect lipid metabolism via the Txnrd2-mtROS-Usp4-Pparα pathway, which provides the new target for NAFLD prevention and treatment. Conclusion: Se ameliorated OFO-induced lipotoxicity via the inhibition of mitochondrial oxidative stress, remodeling of Usp4-mediated deubiquitination, and stabilization of Pparα. Antioxid. Redox Signal. 40, 433-452.

Interactive influences of dietary selenium and oxidized fish oil on growth, nutritional composition, muscle development, antioxidant responses and selenoprotein expression in the muscle of yellow catfish Pelteobagrus fulvidraco

The current study is conducted to determine the influences of dietary selenium (Se) and oxidized fish oil (OFO) on growth, nutritional composition, muscle development, antioxidant responses and selenoprotein expression in the muscle of yellow catfish. We used the 2 × 2 factorial experimental design, which included two dietary Se levels at 0.25 (adequate) and 0.5 (high) mg Se/kg diets, and each Se level had fresh fish oil (FFO) and OFO, respectively. The experiment continued for 10 weeks. Compared to FFO group, dietary OFO reduced final body weight (FBW), specific growth rate (SGR) and weight gain (WG), and the contents of n-6 polyunsaturated fatty acid (PUFA), 18: 2n-6, 20: 4n-6, n-3 PUFA, 20: 5n-3, 22: 6n-3 and total PUFA, the diameters of muscle fibers >80 μm, mRNA expression of mef2d, myf5, myod, s6kb and mTOR, and the ratio of p-mTOR to mTOR protein expression, but increased feed conversion rate (FCR), muscle lipid content, malic enzyme (ME) and isocitrate dehydrogenase (ICDH) activities, the number of the muscle fiber with the diameter lower than 50 μm; high dietary Se addition alleviated OFO- induced variations of these indices mentioned above. Dietary OFO also reduced muscle catalase (CAT) and glutathione peroxidase (GPX) activities and total antioxidant capacity (AOC), and mRNA expression of gpx1, gpx2, gpx3, selenoe, selenok and selenos, but increased total superoxide dismutase (SOD) activity, malondialdehyde (MDA) content and NRF2 protein expression, and high dietary Se addition alleviated OFO-induced changes of these parameters involved in antioxidant responses and selenoprotein expression in the muscle of yellow catfish. Based on these observations above, dietary Se addition alleviated OFO-induced lipogenesis, and reversed the OFO-induced inhibition of muscle growth and development, and oxidative damage of muscle. Our study provides new mechanistic insights into the Se and OFO interaction in fish. Statement of relevanceThe biological basis through which dietary OFO and Se diets interacted to affect muscle metabolism and physiology is scarce. Our study indicated that dietary Se could alleviate OFO-induced negative effects on muscle metabolism and physiology, which will be helpful to the feed formulation and fish farm.

ZIF-derived porous carbon supported cobalt and selenium dual sites enhanced oxygen reduction reaction

Non-noble metal based oxygen-reduction electrocatalysts with high performance in acidic medium are of great importance to application of proton exchange membrane fuel cells (PEMFCs). Dual-sites catalysts with rational design are essential to promote the sluggish kinetics of oxygen reduction reactions (ORR) owing to the synergistic effect. However, the study of dual sites is mainly based on metal atom pairs and need further mechanism exploration for guiding the reasonable design. Herein, a novel designed dual-sites electrocatalyst with high dispersed Co-Nx and Se–C dual sites embedded in ZIF-derived porous carbon frameworks was successfully synthesized, which displayed a positive ORR activity with a half-wave potential of 0.764 V (vs. RHE) as well as a high stability in 0.5 M H2SO4. Besides, the prepared Co–Se–N–C-2 sample exhibited a high ORR activity with a peak power density of 297 mW cm−2 and a low charge-transfer resistant of 0.326 Ω when this catalyst was employed in the H2/O2 fuel cell test. Furthermore, experimental characterizations and theoretical calculations revealed that the constructed Co/Se dual sites had multiple effects. In addition to providing additional active sites, the introduction of Se can effectively modulate the charge redistribution, enhance the efficiency of charge transfer, and reduce the energy barrier of the desorption process of the ORR pathway. These multiple effects promote the ORR kinetics and improve the catalytic performance.

Effect of Selenium Application on Growth, Antioxidative Capacity, and Nutritional Quality in Purple Lettuce Seedlings

Selenium (Se) is involved in the growth and development of plants. More importantly, Se from plant foods is a primary source of Se intake for humans and animals. Improving the Se content in vegetables through biofortification is an effective way to solve the hidden hunger induced by Se deficiency. This study demonstrated the effect of different exogenous Se application concentrations on the growth, antioxidative capacity, and nutritional quality of purple lettuce (Lactuca sativa var. crispa L. “Purple Rome”) at the seedling stage. The low Se application concentration (≤8 μM) significantly promoted the lettuce seedling growth. Conversely, the high Se application concentration (16 μM) inhibited the seedling growth and overproduced the reactive oxygen species in lettuce root tips, which caused oxidative damage to membrane lipids and cell death. Furthermore, the enzyme activities and gene expression of the antioxidant enzymes, superoxide dismutase-peroxidase, and catalase, were significantly increased under exogenous Se application. The exogenous Se application significantly increased the accumulation of nutrients in purple lettuce at the seedling stage. Remarkably, the exogenous Se application concentrations were significantly positively related to the Se and anthocyanin contents. The gene expression levels of chalcone synthase were positively correlated with the anthocyanin contents under exogenous Se application. This study contributes to the role of Se in lettuce growth and provides a reference for producing high-quality purple lettuce rich in Se and anthocyanins.

Association of Selenium Intake and Selenium Concentrations with Risk of Type 2 Diabetes in Adults: A Narrative Review.

Several recent studies have suggested selenium (Se) as a potential risk factor for diabetes mellitus (DM); however, the relationship between high Se levels and type 2 diabetes mellitus (T2DM) risk remains unclear. This review article aimed to provide a comprehensive discussion to clarify the association between high dietary Se intake and blood Se concentrations and the risk of T2DM among adults. We conducted searches in the PubMed, Science Direct, and Google Scholar databases for the years 2016 to 2022 and evaluated 12 articles from systematic reviews, meta-analyses, cohort studies, and cross-sectional studies. This review found a controversial association between high blood Se concentrations and T2DM risk while demonstrating a positive correlation with DM risk. In contrast, there are conflicting results regarding the association between high dietary Se intake and T2DM risk. Thus, longitudinal studies and randomized controlled trials are needed to better elucidate the link.

Effects of selenite on the responses of lettuce (Lactuca sativa L.) to polystyrene nano-plastic stress

Nowadays, nano-plastics are widespread in agricultural soils and could be uptaken by crops to cause an increased risk for food safety. As a beneficial element for plants, selenium (Se) can alleviate oxidative damages under various environmental stresses (eg. heavy metals, heat, cold). This study investigated the single and co-applications of nano-size polystyrene (PS) (80 nm and 200 nm) and selenite (0.8 ppm and 5 ppm) in lettuce (Lactuca sativa L.). Results showed nano-PS significantly decreased the root-shoot fresh biomass ratios, inhibited physiological functions in roots and leaves (e.g. root length, chlorophyll content and net photosynthetic rate), as well as stimulated the activities of the antioxidant enzymes in roots and shoots with greater toxicity at the smaller particle size (80 nm). However, both exogenous selenite applications significantly alleviated the above toxic effects of nano-PS in lettuces, especially at a high Se level of 5 ppm. Regression Path Analysis (RPA) revealed that regulation of chlorophyll levels by Se might be a key mechanism for counteracting PS stress in lettuces, which led to the increase in indigenous defense capacity. The present findings provide a novel but safer and cleaner agricultural strategy to alleviate or minimize nano-plastics toxicity in agricultural soils for staple crops and vegetables via application of Se.

An engineered biochar for treatment of selenite contaminated water: Mass transfer characteristics in fixed bed adsorption

Biochar composites have been gaining attention in recent years as a promising and cost-effective material for wastewater treatment. In the present study, a novel procedure was developed to create a biochar (BC) composite impregnated with binary zinc (Zn) and iron (Fe) oxides (denoted as ZnFeBC). The procedure was optimized to enhance selenite, Se(IV), adsorption performance of the ZnFeBC composite. The modified biochar composite had excellent pore characteristics with a specific surface area of 854 m2/g. The maximum Se(IV) adsorption capacity of an unary Zn-loaded biochar composite was 520 µg/g, which significantly increased to 4,100 µg/g after the iron oxide impregnation. Isotherm experiments suggested that the adsorption process was likely through homogeneous monolayer adsorption. The ZnFeBC composite exhibited excellent performance over a broad range of pH values, with the highest Se(IV) adsorption capacities observed at lower pH values (maximums at pH 3). X-ray absorption near edge structure spectroscopy (XANES) indicated that the redox reaction of Se oxyanions did not occur during the adsorption process. ZnFeBC was successfully used to remove Se(IV) from a mining lake water matrix in a fixed-bed adsorption system. Additionally, a mass transfer model optimizing effective diffusion and external mass transfer coefficients was developed to comprehensively assess the adsorption system. Overall, ZnFeBC exhibited great potential as an adsorbent for treating Se(IV) contaminated waters and the developed mass transfer model is useful for scaling up fixed-bed adsorption systems.

0737 Age, menstrual phase, and circadian preference impact sleep in menstruating individuals

Abstract Introduction An eveningness chronotype is generally associated with reduced sleep continuity and quality, as well as social jetlag. Changes in hormones and menstrual phase similarly impact sleep, although research on the chronobiological effects of these changes are equivocal. This study aimed to examine the role of menstrual cycle in daily self-report and actigraphy-assessed sleep in two consecutive menstrual cycles. Methods Participants (n=51; 43% Caucasian), 18-35 years (23.67±4.68) completed actigraphy and daily sleep diaries over two menstrual cycles (m days=51.29). Four menstrual phases were identified via dates of menstrual bleeding and urinary ovulation testing: perimenstrual (±3 days of bleeding), mid-follicular, periovulatory, and mid-luteal. Relationships between menstrual phase and sleep parameters were estimated using multistep hierarchical linear modeling. Subjective and objective measures yielded the following sleep variables: Total Wake Time (TWTsub and TWTobj), Sleep Efficiency (SEsub and SEobj), and mid-sleep point (MSP). Participants completed the Morning-Eveningness Questionnaire (MEQ) at baseline. Results Mean cycle length was 28.61 days±2.69. Age was significantly associated with TWTobj (r=-.32, p &amp;lt;.001); SEobj (r=.34, p &amp;lt;.001), and MSP (r=-.42, p &amp;lt;.001) such that older participants had shorter TWT, higher SE, and earlier MSP. TWTobj was 4-7 minutes lower during the mid-follicular (61.54±3.37) and mid-luteal phases (63.11±3.29) compared to the perimenstrual phase (67.54±3.37; p &amp;lt;.001). SEobj was higher in the mid-luteal phase (82.50±0.79) vs. the perimenstrual phase (80.71±0.82, p =.006). Perimenstrual women reported 8-16 minutes longer awake (TWTsub=52.23±5.01, p &amp;lt;.001) and had 1-3% reduction in SEsub (89.70±0.10, p &amp;lt;.001). MEQ negatively predicted TWTobj (p=.004) and SEobj (p=.003), but did not vary across menstrual phase. In morning-type individuals, TST was significantly higher in the periovulatory (b =1.81, p=.01) and mid-luteal phases (b=2.03, p&amp;lt;.001) compared to the perimenstrual phase. Conclusion With increasing age, women experienced reduced time awake, higher sleep efficiency, and earlier sleep timing. Eveningness predicted greater total wake time and lower sleep efficiency. With menstrual phase considered, disturbed sleep was highest in the perimenstrual phase and women reporting a stronger preference for eveningness reported shorter TST during the perimenstrual phase. These findings highlight the importance of considering the menstrual cycle in the sleep health of menstruating individuals. Support (if any)

Irrigation leads to new Se-toxicity paddy fields in and around typical Se-toxicity area

Although the issue has been of much concern and has subsequently been controlled for years, the environmental risk of excess selenium (Se) in farmlands still has not been eliminated in Se-toxicity areas. Different types of farmland utilization can change Se behavior in soil. Thus, located field monitoring and surveys of various farmland soils in and around typical Se-toxicity areas spanning eight years were conducted in the tillage layer and deeper soils. The source of new Se contamination in farmlands was traced along the irrigation and natural waterway. This research indicated that 22 % of paddy fields increased to Se-toxicity in surface soil led by irrigation with high-Se river water. Selenate is the dominant Se species in rivers (90 %) originating from geological background areas with high Se. Both soil organic matter (SOM) and amorphous iron content played important roles in the fixation of input Se. Thus, available Se was increased by more than twofold in paddy fields. The release of residual Se and eventual bounding by organic matter is commonly observed, thus suggesting that stable soil Se availability seems sustainable for a long time. This study is the first report in China that shows how new soil Se-toxicity farmland is caused by high-Se water irrigation. This research warns that external attention should be paid to the selection of irrigation water in high-Se geological background areas to avoid new Se contamination.

Selenium-mediated Cr(VI) reduction and SeNPs synthesis accelerated Bacillus cereus SES to remediate Cr contamination

Microbial biotransformation of Cr(VI) is a sustainable approach to reduce Cr(VI) toxicity and remediate Cr(VI) contamination. In this study, Bacillus cereus SES with the capability of reducing both Cr(VI) and Se(IV) was isolated, and the effect of Se supplementation on Cr(VI) reduction by Bacillus cereus SES was investigated. Se(IV) addition enabled 2.6-fold faster Cr(VI) reduction, while B. cereus SES reduced 96.96% Se(IV) and produced more selenium nanoparticles (SeNPs) in the presence of Cr(VI). Co-reduction products of B. cereus SES on Cr(VI) and Se(IV) were SeNPs adsorbed with Cr(III). The relevant mechanisms were further revealed by proteomics. Se(IV) supplementation mediated the synthesis of Cr(VI) reductants and stress-resistant substances, thus enhancing Cr(VI) resistance and promoting Cr(VI) reduction. Meanwhile, high Se(IV) reduction rate was associated with Cr(VI)-induced electron transport processes, and Cr(VI) mediated the up-regulation of flagellar assembly, protein export and ABC transporters pathways to synthesis and export more SeNPs. Furthermore, Se combined with B. cereus SES had the potential to reduce the toxicity of Cr(VI) via reducing the bioavailability of Cr and improving the bioavailability of Se in soil. Results suggested that Se could be an efficient strategy to enhance the remediation of B. cereus SES on Cr contamination.

Mercury and selenium co-ingestion assessment via rice consumption using an in-vitro method: Bioaccessibility and interactions

Mercury (Hg) was reported to accumulate in rice grains, and, together with the selenium (Se) was found in rice, the co-exposure of Hg-Se via rice consumption may present significant health effects to human. This research collected rice samples containing high Hg:high Se and high Se:low Hg concentrations from high Hg and high Se background areas. The physiologically based extraction test (PBET) in vitro digestion model was utilized to obtain bioaccessibility data from samples. The results showed relatively low bioaccessible for Hg (<60%) and Se (<25%) in both rice sample groups, and no statistically significant antagonism was identified. However, the correlations of Hg and Se bioaccessibility showed an inverse pattern for the two sample groups. A negative correlation was detected in the high Se background rice group and a positive correlation in the high Hg background group, suggesting various micro forms of Hg and Se in rice from different planting locations. In addition, when the benefit-risk value (BRV) was calculated, some “fake” positive results showed while Hg and Se concentrations were directly used, which indicated that bioaccessibility should not be neglected in benefit-risk assessment.

Mantle plume plays an important role in modern seafloor hydrothermal mineralization system

Deyin-1 hydrothermal field is located on the Southern Mid-Atlantic Ridge (SMAR) 15°S. The geochemical characteristics of substrate basalts record the incorporation of Saint Helena plume components in the magma source, which implies that the hydrothermal mineralization characteristics in Deyin-1 might be influenced by the mantle plume indirectly. In this study, the pyrite trace element contents and sulfide in situ Pb and He-Ar isotope compositions of a chimney sample from Deyin-1 field are determined systematically in order to clarify the mantle plume influence on local hydrothermal mineralization process. The higher Ba/Co ratios in Deyin-1 pyrites, compared with those from other mid-ocean ridge hydrothermal fields, may be related to the Saint Helena mantle plume influence. Besides, Deyin-1 pyrites possess lower Pb/As, Ag/As, Ni/As ratios and higher As contents than ultramafic-hosted hydrothermal fields, indicating the Deyin-1 is a mafic-hosted hydrothermal system. The higher Se, Co and lower Zn, As, Pb contents in pyrites from interior layers of the chimney demonstrate that the fluid temperature increases during the chimney growth. The in situ Pb isotope compositions of Deyin-1 sulfides are similar to those of mantle plume-influenced basalts in SMAR 15°S and more radiogenic than that of the plume-free SMAR basalt, which demonstrates that the Saint Helena mantle plume has contributed parts of Pb (and other metal elements) to the Deyin-1 sulfides. The He isotope compositions of Deyin-1 sulfides also prove the mantle plume contribution to the hydrothermal system. End-member mixing calculation of Pb-He isotopes indicates that the Saint Helena plume components account for about 3% of the mineralization material sources in Deyin-1 sulfides. Many hydrothermal fields have been discovered near the hot spots besides Deyin-1. Our study emphasizes that mantle plume influence on hydrothermal mineralization might be ubiquitous and needs to be revaluation. This study might shed some light on modern seafloor hydrothermal mineralization process and lithosphere-seawater mass exchange.

Molecular Mechanism of Exogenous Selenium Affecting the Nutritional Quality, Species and Content of Organic Selenium in Mustard

It is an essential method for healthy Selenium (Se) supplementation to convert exogenous Se into organic Se via crops. Brassica juncea (L.) Czern (leaf mustard) was employed as plant material in this investigation and was treated with sodium selenite (Na2SeO3). Its physiological indicators, nutritional quality, antioxidant enzyme activity, total Se content, and Se morphology were all evaluated. The absorption, transportation, and transformation mechanisms of Se in mustard were studied using transcriptome data. The results revealed that low concentration of Se treatment promoted the growth of mustard, while high concentration Se treatment inhibited it. The concentration of 10 mg/L Na2SeO3 treatment had the best growth parameters for mustard. Compared to the control group, the content of vitamin C (Vc) and anthocyanins in the treatment group increased to varying degrees, while the content of flavonoids, total phenols, soluble sugar, and soluble protein increased first and then decreased. Five Se forms, Se (IV), Se (VI), selenocystine(SeCys2), selenomethionine (SeMet), and methylselenocysteine (MeSeCys), were detected in the Na2SeO3 treatment group, with organic Se accounting for over 95%. Na2SeO3 treatment can significantly reduce the accumulation of ROS in mustard plants and enhance their stress resistance. Transcriptome data and metabolite association analysis showed that PHO1-H8 promoted the absorption of Na2SeO3 by mustard roots, while SULTR3;3 and SULTR4;1 promoted the transport of Se from roots to the aboveground portion and chloroplasts. Se in mustard was transformed into SeMet, SeCys, MeSeCys, and selenoprotein through the action of genes such as APS, APR, and SEP1, and stored in plant leaves.

Highly flexible, PEDOT:PSS-polyvinylpyrrolidone coated carbon nanofiber-polydimethylsiloxane composite for electromagnetic interference shielding

Lightweight, flexible and portable electronics, and wearable devices are recognized as the next-generation electronic devices. Rapid growth in the usage of such devices will add to electromagnetic interference (EMI) or EM pollution in an alarming magnitude. Hence, lightweight, hydrophobic, and flexible EMI shielding materials capable of effectively reducing EMI are urgently required. The present work reports fabrication of poly(3,4-ethylenedioxythiophene): polystyrene sulfonate (PEDOT:PSS) and polyvinylpyrrolidone (PVP) coated, carbonized electrospun polyacrylonitrile (PAN) nanofiber (CNF) and their flexible polydimethylsiloxane (PDMS) composites. The material showed excellent EMI shielding effectiveness of 44 dB in the frequency range of 8–26.5 GHz with a thickness of 0.06 mm due to the synergetic effect of CNF matrix, PEDOT: PSS, and PVP. It also exhibited a high absolute EMI SE of 5678 dB cm2 g−1 with low loading of PEDOT:PSS-PVP. Here, PEDOT:PSS-PVP/CNF shows EMI shielding through an absorption dominated mechanism rather than reflection. These findings indicate the potential of these composites as thin, flexible, hydrophobic, and lightweight EMI shielding materials for practical applications.

Characterization and tissue expression of twelve selenoproteins in yellow catfish Pelteobagrus fulvidraco fed diets varying in oxidized fish oil and selenium levels

BackgroundSelenium (Se) functions through selenoproteins and is essential to growth and metabolism of vertebrates. The present study was conducted to identify twelve selenoproteins genes (selenoe, selenof, selenoh, selneoi, selenom, selenok, selneon, selenoo, selenot, selenos, selenou and msrb1) from yellow catfish. Their mRNA expression patterns, as well as their response to dietary oxidized fish oils and Se addition were explored. MethodsWe use 3′and 5′ RACE PCR to clone full-length cDNA sequence of twelve selenoprotein genes from yellow catfish. Their mRNA expression patterns were assessed via quantitative real-time PCR. Yellow catfish were fed diet adequate Se+ fresh fish oil, adequate Se+ oxidized fish oil, high Se+ fresh fish oil and high Se+ oxidized fish oil, respectively, for 10 weeks. Their kidney, heart, brain and testis were used to assess the mRNA expression of twelve selenoprotein. ResultsTwelve selenoprotein genes had similar domains with mammals and the other fish. Their mRNAs were expressed widely in eleven tissues but varied with the tissues. Dietary oxidized fish oils and Se addition influenced their mRNA abundances of twelve selenoproteins in a tissue-dependent manner. ConclusionOur study demonstrated the characterization and expression of twelve selenoproteins, and elucidated their responses in yellow catfish fed diets varying in oxidized fish oils and Se addition, which increased our knowledge into the biological function and regulatory mechanism of Se and selenoproteins in fish.

Concentrations, distribution and influencing factors of selenium (Se) in soil of arid and semi-arid climate: A case from Zhangye-Yongchang region, north-western China

Selenium (Se) is an essential trace element for human health. It is therefore important to investigate Se geochemical characteristics in the environment. However, less attention has been paid to the supergene geochemistry of selenium in alkaline soils. Based on a recently-completed geochemical survey in the Zhangye-Yongchang region of north-western China, this paper first summarizes the concentrations and spatial distribution of Se in the topsoil therein, and then discuss the influencing factors through multivariate statistical analysis, and study the bio-availability of soil Se. Our results showed that the contents of Se in the topsoil of the Zhangye-Yongchang range from 0.07 to 0.88 mg/kg, and the average concentration was 0.255 mg/kg. The Se-rich soil samples were mainly distributed in the Zhangye city and surrounding counties and towns, mainly including Dongyuan town, Shandan County, and Huocheng town of Minle county, and the potential Se-deficiency areas contain northern Dongyuan Town where develops sandy land, and Shigangdun town that covered by Gobi Desert. Relatively high Se background in local strata points out that the soil parent material is the dominant controlling factor of the Se concentrations in the topsoil. Results from factor analysis, cluster analysis and correlation analysis suggest a positive relationship between Se and F, Mo, Sr, U, MgO, CaO, and organic matter, but negative relationship between Se and SiO2 and pH value. Organic matter and certain oxides are likely to be the adsorbent of soil Se. Moreover, a high proportion of water-soluble and ion-exchange state Se (7.66 % of the total contents) and a high Se enrichment rate of crops (>30 %) indicate high bio-availability of soil Se in the Zhangye-Yongchang region, where could probably develop a green industry of Se-rich agricultural products in the future.

Time-Resolved Examination of Fungal Selenium Redox Transformations.

Selenium (Se) is both a micronutrient required for most life and an element of environmental concern due to its toxicity at high concentrations, and both bioavailability and toxicity are largely influenced by the Se oxidation state. Environmentally relevant fungi have been shown to aerobically reduce Se(IV) and Se(VI), the generally more toxic and bioavailable Se forms. The goal of this study was to shed light on fungal Se(IV) reduction pathways and biotransformation products over time and fungal growth stages. Two Ascomycete fungi were grown with moderate (0.1 mM) and high (0.5 mM) Se(IV) concentrations in batch culture over 1 month. Fungal growth was measured throughout the experiments, and aqueous and biomass-associated Se was quantified and speciated using analytical geochemistry, transmission electron microscopy (TEM), and synchrotron-based X-ray absorption spectroscopy (XAS) approaches. The results show that Se transformation products were largely Se(0) nanoparticles, with a smaller proportion of volatile, methylated Se compounds and Se-containing amino acids. Interestingly, the relative proportions of these products were consistent throughout all fungal growth stages, and the products appeared stable over time even as growth and Se(IV) concentration declined. This time-series experiment showing different biotransformation products throughout the different growth phases suggests that multiple mechanisms are responsible for Se detoxification, but some of these mechanisms might be independent of Se presence and serve other cellular functions. Knowing and predicting fungal Se transformation products has important implications for environmental and biological health as well as for biotechnology applications such as bioremediation, nanobiosensors, and chemotherapeutic agents.