Total Se Research Articles

Partitioning of selenium from coal to fly ash: The key roles of Fe-bearing minerals and implications for Se potential recovery

The roles of Ca/Fe phases on selenium (Se) enrichment behavior in fly ash during coal combustion were investigated by examining the Ca/Fe mineralogy of various ash samples, exploring the binding forms of Se in fly ashes, and performing bench-scale adsorption experiments (150–1000 ℃). The results indicated that Se capture by fly ash is a function of flue gas temperature, particle size, and more importantly, the contents and form of Ca/Fe in combustion ash. Physical condensation/adsorption was mainly determined by temperature and particle size, contributing to less than 25% of total Se in fly ash. The remaining Se in fly ash was captured by chemical reactions of Se with ash components. Calcium in ash mostly was present as Ca-aluminosilicates, Ca-silicates, gypsum, or complex Ca-Al-Si-Fe-O mixed phases. Iron mainly occurred as Fe-silicates and some crystalline minerals including hematite, magnetite, and maghemite. Although adsorption experiments found that only CaO was able to capture SeO2 (g) at high temperature (> 900 ℃), the roles of lime as well as Fe2+-/Fe3+-silicates (conclusion from previous literature) can be excluded, as inferred from the small amount of CaO in ash and the lack of correlation between Fe-silicate and Se. Sequential extraction experiments and electron microscopy analysis revealed that Fe-bound Se was dominant and iron oxides might be the critical phase for Se retention. Simulated adsorption experiments demonstrated that magnetite had the best Se capture ability among the iron minerals. The extraction of Fe-bound Se from coal fly ash required more stringent conditions than that of physiosorbed-Se and Ca-bound Se. Therefore, pretreatment methods including magnetic separation, flotation, size segregation, etc. were suggested to be used prior to acid leaching. This study can provide scientific basis for developing high-efficiency Se recovery methods or Se emission control techniques for high-Se coal utilization in thermal power stations.

Effects of Sodium Selenite on the Rhizosphere Environment, Growth, and Physiological Traits of Oilseed Rape (Brassica napus L.)

Soil selenium (Se) speciation characteristics and their influence on the Se enrichment pattern and physiological characteristics of oilseed rape are poorly understood. We investigated dynamic changes in rhizosphere soil physicochemical properties, Se uptake and partitioning, biomass, and physiological indices in oilseed rape under five exogenous Se condition levels (0, 1.0, 2.5, 5.0, and 10.0 mg kg−1 Se in sodium selenite) using soil cultivation experiments. The rhizosphere pH and dissolved organic carbon in the soil solution were higher than those of the non-rhizosphere soil solution. The total Se, water-soluble Se, exchangeable Se, and organic Se contents in soils, as well as rapeseed root/leaf Se contents, significantly increased with increasing exogenous Se. Under 2.5 mg kg−1 Se, the biomass of rapeseed roots and leaves increased at the sixth week (82% and 58%) and eighth week (48% and 32%), respectively, reaching the highest level. Applications of 5.0 mg kg−1 Se at 6 and 8 weeks significantly increased the glutathione peroxidase activity (49%/82%), and decreased malondialdehyde content (23%/39%). Canonical correlation and ridge regression analyses showed that Se in the rapeseed roots/leaves significantly and positively correlated with water-soluble Se, exchangeable Se, and organic Se in rhizosphere soil. Overall, moderate-concentration Se soil application benefited oilseed rape growth (optimum = 2.5 mg kg−1 Se). Our findings reveal the response of oilseed rape to soil Se application based on plant growth and physiological traits, rhizospheric soil solution properties, and Se speciation transformation.

Sensitive analysis of selenium speciation in natural seawater by isotope-dilution and large volume injection using PTV-GC-ICP-MS

Although oceans play a key role in the global selenium (Se) cycle, there is currently very little quantitative information available on the distribution of Se concentrations and Se speciation in marine environments. In general, determining Se concentration and speciation in seawater is highly challenging due to very low Se levels ((sub)ng⋅L−1), whereas matrix elements interfering Se pre-concentration and detection are up to the g⋅L−1 levels. In this study, we established a sensitive method for the determination of the various Se chemical fractions present in natural seawater, i.e. selenite (SeIV), selenate (SeVI), organic Se-II + Se0 and total Se, using species-specific isotope dilution gas chromatography coupled to inductively coupled plasma mass spectrometry (ID-GC-ICP-MS). We compared different derivatization reagents and optimized specific pre-treatment protocols, including a microwave assisted oxidation protocol for the determination of total Se and organic Se-II + Se0 using H2O2. To increase sensitivity, we developed an online pre-concentration method based on large volume injection (LVI) using a programmed temperature vaporization (PTV) inlet. Eventually, the developed method achieved low absolute and methodological detection limits, i.e., respectively, 0.1–0.3 pg and 0.9–3.1 ng.L-1 for the different fractions. The accuracy of our method was of 2% for a certified reference material (CRM) diluted in artificial seawater while the precision was better than 4% for a freshwater CRM in artificial seawater matrix as well as two common seawater CRMs certified for trace elements excluding Se. As a proof-of-concept, we quantified the various Se fractions in a large number of natural water samples from the Baltic and North Seas, encompassing a wide range of salinity (7–35 psu), which shows that its detection limits are sufficient to determine total Se, SeIV, SeVI and organic Se-II + Se0 concentrations in brackish and marine systems.

Determination of selenium in cereal and biofortified samples by ICP-OES using an alcohol-based deep eutectic solvent in digestion procedure

The application of deep eutectic solvents (DESs) as green solvents in analytical chemistry has attracted increasing attention. The present study presents a simple, eco-friendly, and cost-effective approach for the extraction of selenium (Se) in food samples. The extraction method utilised alcohol-based DES and inductively coupled plasma optical emission spectrometry (ICP-OES) to determine total Se. Factors affecting the extraction procedure were optimised using the design of experiments. Using the optimal conditions, the limits of detection (LOD) and quantification (LOQ) and linearity of the developed method were 0.0011 µg Se/g, 0.0037 µg Se/g and 0.004–0.20 µg Se/g, respectively. The precision expressed as relative standard deviations (RSDs) was less than 10 %. The accuracy of the method was investigated using certified reference materials (IRMM 804 Rice Flour and NIST SRM 1567b wheat flour), and the results were in close agreement with the certified values (0.038 µg/g and 1.14 µg/g) with percentage recoveries ranging from 89.5 to 106 %. The interday ( %RSD) and Intraday ( %RSD) were 2.8–5.4 % and 4.3–5.9 %, respectively. The greenness of the method was assessed using NEMI, AES, and AGREE metrics tools. When comparing all these tools, they all qualified the proposed method as green.

Water extract of Fagopyrum dibotrys (D. Don) Hara straw increases selenium accumulation in peach seedlings under selenium-contaminated soil

To promote the selenium (Se) uptakes in fruit trees under Se-contaminated soil, the effects of water extract of Fagopyrum dibotrys (D. Don) Hara straw on the Se accumulation in peach seedlings under selenium-contaminated soil were studied. The results showed that the root biomass, chlorophyll content, activities of antioxidant enzymes, and soluble protein content of peach seedlings were increased by the F. dibotrys straw extract. The different forms of Se (total Se, inorganic Se, and organic Se) were also increased in peach seedlings following treatment with the F. dibotrys straw extract. The highest total shoot Se content was treated by the 300-fold dilution of F. dibotrys straw, which was 30.87% higher than the control. The F. dibotrys straw extract also increased the activities of adenosine triphosphate sulfurase (ATPS), and adenosine 5'-phosphosulfate reductase (APR) in peach seedlings, but decreased the activity of serine acetyltransferase (SAT). Additionally, correlation and grey relational analyses revealed that chlorophyll a content, APR activity, and root biomass were closely associated with the total shoot Se content. Overall, this study shows that the water extract of F. dibotrys straw can promote Se uptake in peach seedlings, and 300-fold dilution is the most suitable concentration.

Life-cycle selenium accumulation and its correlations with the rhizobacteria and endophytes in the hyperaccumulating plant Cardamine hupingshanensis

Cardamine hupingshanensis (C. hupingshanensis) is known for its ability to hyperaccumulate selenium (Se). However, the roles of the rhizobacteria or endophytes in Se hyperaccumulation have not been explored in C. hupingshanensis. Here, in-situ-like pot experiments were conducted to investigate the characteristics of Se accumulation throughout C. hupingshanensis growth stages and its correlations with rhizobacteria and endophytes under varying soil Se levels. Results showed that Se levels in roots, stems and leaves increased from the seedling to bolting stage, but remained relatively stable during the flowering and maturity. Leaves exhibited the highest Se levels (736.48 ± 6.51 mg/kg DW), followed by stems (575.39 ± 27.05 mg/kg DW), and lowest in roots (306.62 ± 65.45 mg/kg DW) under high-Se stress. The Se translocation factors from soils to C. hupingshanensis roots was significantly higher (p < 0.05) in low-Se soils compared to medium- and high-Se soils. Rhizobacterial diversity showed significant positive correlations (p < 0.05) with both total and bioavailable soil Se contents. The levels of soil Se and growth stages of C. hupingshanensis were found to have significant effects (p < 0.03) on the compositions of rhizosphere bacteria and C. hupingshanensis endophytes. Low-abundance bacteria (< 5%), including Gemmatimonadetes, Latescibacteria and Nitrospirae, were identified to potentially increase the bioavailable Se levels in the rhizosphere. The Se accumulation significantly decreased (p < 0.05) in C. hupingshanensis grown in sterilized low- (32.4%), medium- (17%) and high-Se (42%) soils. Endophytes in C. hupingshanensis, such as Firmicutes and Proteobacteria, were likely recruited from the rhizobacteria, as evidenced by the isolated bacterial strains, and played an important role in Se hyperaccumulation, particularly during the flowering stage. This study provides new insights into potential mechanism underlying Se hyperaccumulation in C. hupingshanensis.

Selenium, Selenoproteins and 10-year Cardiovascular Risk: Results from the ATTICA Study.

Selenium (Se) is an essential trace element that is involved in several pathophysiological functions. The relationship of Se with cardiovascular disease remains inconclusive, especially regarding the role of different selenospecies. The present study assessed the levels of Se distribution in plasma selenoproteins, namely glutathione peroxidase 3 (GPx3), selenoprotein P (SelP) and selenoalbumin (SeAlb) and total Se in selenoproteins in relation to 10-year cardiovascular risk in the ATTICA prospective study. A sub-sample from the ATTICA Study's database, consisting of 278 subjects (114 women and 164 men) with data on Se and selenoproteins levels, was considered. SeGPx3, SelP, and SeAlb in human plasma were simultaneously determined by high-performance liquid chromatography (HPLC) coupled with inductively coupled plasma mass spectrometry (ICP-MS) at baseline. The duration of the follow-up was 8.74 ±2.36 years (mean± standard deviation) and cardiovascular outcomes were recorded. Cox proportional hazards models were applied with total Se or selenoprotein Se as independent variables adjusted for several covariates. Total Se in selenoproteins was positively related to 10-year relative risk of cardiovascular disease (Hazard Ratios of 3rd vs 2nd tertile 10.02, 95% CI:1.15, 92.34). Subjects with high Se but low SeGPx3, as identified by discordant percentiles in the distribution of SeGPx3 and Se, had a higher cardiovascular risk. The differentiated effects of circulating selenoproteins on cardiovascular disease risk in the present study, suggest the importance of redox regulation by specific selenoproteins.

Isolation and identification of green alga Chlorella vulgaris HNUFU001 for environmental selenium enrichment in heterotrophic growth regime

Microalgae, particularly Chlorella, have promising selenium (Se) enrichment capacity and great potential in wastewater treatment and the development of nutraceuticals. To acquire Chlorella strains with strong heterotrophic propensity and robust Se tolerance, this research utilized a heterotrophic isolation strategy along with a high Se concentration medium as selection factors. The combined sequence of the ribosomal small subunit (SSU) and internal transcribed spacer (ITS) was utilized for phylogenetic analysis, and comparative analysis of ITS secondary structures was also integrated to identify the desired strain. A novel subtropical microalgal strain, Chlorella vulgaris HNUFU001 with high Se tolerance, was isolated from water samples in a lake at Hainan University, China. Gaussian process regression was utilized to assess the strain's growth under varying Se concentrations. The intracellular accumulation and extracellular removal of Se were measured using Inductively Coupled Plasma-Mass Spectrometry (ICP-MS) and Inductively Coupled Plasma Optical Emission Spectrometer (ICP-OES), respectively. The maximum intracellular organic Se (92 % of total Se) was observed as 108.835 μg/g dry weight (DW) for 1 mg/L Se treatment. The highest Se removal rate was 40 %. The high Se tolerance and enrichment traits enable Chlorella vulgaris HNUFU001 to be a promising candidate for the heterotrophic production of organic Se-related nutraceuticals.

Design of 3D graphene‐Ni microsphere based polymeric composites for highly efficient and absorption‐dominated electromagnetic interference shielding performance

AbstractThe development of polymeric composites that possess both exceptional electromagnetic interference shielding effectiveness (EMI SE) and high absorption capacity has always been appealing, yet it continues to pose a significant challenge. To this end, we disclose a hollow and spherical shielding unit that could achieve “absorption‐reflection‐attenuation” process for incident electromagnetic (EM) wave, which was fabricated through decorating Ni nanoparticles onto rGO hollow microspheres by virtue of Pickering emulsification method followed by thermal annealing. With integrated magnetic and electric parts, the consequent shielding composite by assembling these microspheres into PDMS displayed not only a favorable EMI SE of 44 dB across the entire x‐band, but also significantly improved absorption performance that has exceeded 95% of the total SE. Moreover, the power coefficient of absorption (A) is up to 0.73 at the pyrolysis temperature of 550°C. Such admirable performance is mainly attributed to the synergistic effect of conductive rGO walls, magnetic Ni nanoparticles, as well as the unique spherical architecture, which has enabled more efficient capture and attenuation of EM waves. Herein, this research has highlighted the development of polymeric composites for high‐performance EMI shielding applications.Highlights Reflection‐absorption‐integrated shielding compartment was designed. Decorating magnetic Ni nanoparticles onto rGO hollow microspheres. High EMI SE with enhanced absorption ability was acquired. Unique structure generating synergistic effect on EMI shielding

Selenium bioaccessibility in rice grains biofortified via soil or foliar application of inorganic Se

Selenium (Se) is a micronutrient for humans, and its deficiency is related to various diseases. Recent studies have proposed strategies to increase Se intake, especially using selenium biofortification in staple foods. However, few investigations shed light on the chemical species and the bioavailability of Se in cereal grains, including rice, one of the most important staple foods worldwide. This study aimed to determine the bioaccessible fractions of Se in rice grains biofortified with inorganic Se species using an in vitro sequential extraction method to simulate human digestion. Samples and extracts were submitted to microwave-assisted acid digestion, and total/bioaccessible Se levels were determined by DRC-ICP-MS. Accurate Se quantification was achieved using matrix-matching calibration. Rice biofortification via foliar application increased Se levels in the bioaccessible fraction more effectively than soil applications. Bioaccessible Se represented, on average, 61 ± 5 % of the total levels. Of the total Se content in rice, 44 ± 4 % was extracted in the gastric step, which is where most protein-bound bioaccessible selenium is degraded. Biofortification with inorganic forms of Se effectively increases the bioaccessible content of this element in food. Still, the amount to be applied must be corrected based on the bioaccessible fraction of the nutrient in rice grains.

Selenium contents, speciation and bioaccessibility of Se-enriched rice grains from Chinese markets

Diet intake accounts for >90% of selenium (Se) exposure in humans, with rice being the main source of Se intake for >60% of the Chinese population. In this study, 48 rice grain samples labeled Se-enriched were obtained from 22 major rice producing areas in China through online sources. Their total Se contents, Se speciation, and Se bioaccessibility were evaluated to provide a holistic view of Se-enriched rice in the market. The total Se contents were 0.006–0.951 ​μg ​g−1 (average 0.249 ​μg ​g−1), which showed great regional variations, with 73% of the samples satisfying the Se-enriched standard based on GB/T22499-2008 (0.04–0.30 ​mg ​kg−1). Over 80% of Se in the rice samples was organic Se species including selenomethionine, selenocysteine and methylselenocysteine, with selenomethionine being the main Se species, accounting for 61–98%. Based on a modified physiologically-based extraction test (MPBET), the Se bioaccessibility in 33 selected samples was 8.05–49.6% (28.6%) in the gastric phase and 18.1–117% (82.5%) in the intestinal phase. Further, Se bioaccessibility was positively correlated with organic Se (r ​= ​0.89–0.93), but not with inorganic Se (selenite and selenate), suggesting that Se bioaccessibility depended on organic Se in these rice grains. The data call for re-evaluation of Se-enriched rice in the market. Further, the potential risk of long-term consumption of Se-enriched rice in the market towards human health should be studied.

Transfer of Se from sediments to the western mosquitofish Gambusia affinis: Tissue distribution, accumulation, and effects on the antioxidant physiology

Selenium (Se) has been shown to cause various toxicities in predatory species (i.e., fish and birds) in Se-contaminated aquatic environments. However, trophic transfer of Se from abiotic environments to freshwater fish has been relatively less addressed. In this study, 2-month-old mosquitofish (Gambusia affinis) were fed Se-enriched oligochaete (Lumbriculus variegatus, exposed to different concentrations of Se(IV) at 0.0, 3.0, 10.0, and 30.0 µg/g dry weight for 7 days) for 45 days. Tissue distribution, Se speciation, and effects on the antioxidant physiology in G. affinis were assessed. The results showed Se was rapidly accumulated in the oligochaete, with 6.30 ± 1.20, 16.20 ± 2.10, and 34.50 ± 2.40 µg/g dw of total Se levels in the worms exposed to 3.0, 10.0, and 30.0 µg/g of Se(IV), respectively. Total Se levels were increased in a dose-dependent manner in fish tissues and Se(IV) from sediments was maternally transferred to the fish embryos. Se-Met-and Se-Cys-were the predominant Se species in the worm and fish tissues, accounting for a minimum of 91.01% of the total Se. Furthermore, increased lipid peroxidation and altered the activities of antioxidant enzymes and levels of GSH were noticed in G. affinis fed the Se-enriched L. variegatus. This study has demonstrated that Se(IV) is transferred from an abiotic vector to freshwater organisms, disturbing the antioxidant physiology in G. affinis and potentially their offspring. This study highlights the importance of dietary exposure on the accumulation and toxicity of Se in aquatic organisms.

Assessment of Membrane and Electrochemical Technologies for the Treatment of a Selenium-Bearing Mine water: Technology Performance and Effect on Toxicity and Bioaccumulation

Nanofiltration (NF), reverse osmosis (RO), electrodialysis (ED), and electrocoagulation (EC), were all tested at the bench scale for removing selenium (Se) from mine water. All of these technologies reduced the concentration of total Se from 216 µg/L (i.e. 120.1 µg/L of selenate; 59.1 µg/L of selenite, and 0.6 µg/L methyl-selenic acid) in the raw mine water to about 2 µg/L or less in the treated water, equivalent to more than 99% removal. Electrodialysis was found to be the most effective, removing more than 99.5% of the Se. The untreated mine water was toxic to algae. In contrast, RO and NF reduced the toxicity of the mine water, allowing algae to grow between 15,000 to 25,000 cells/mL, while ED and EC did not allow algal growth, likely due to complete removal of essential minerals (ED) or the presence of other contaminants (EC), such as copper. The Se speciation did not change as a result of membrane filtration; however, selenite in the effluent was almost fully transformed to selenate in the brines from the ED and EC treatment processes. The effluent treated by NF and EC generated seleno-cyanate at 0.37 and 1.01 µg/L, respectively. Further testing is recommended at the pilot-scale with the same mine water as well as different mine water.

Selenium quantification in wastewaters from selected coal-fired power plants and river waters in South Africa using ICP-MS

South Africa mainly relies on Eskom's coal-fired power plants for electricity generation. However, the use of coal causes several adverse environmental impacts, including the release of selenium into the hydrosphere. Selenium is an essential nutrient for humans, animals, and microbes, but excess selenium is toxic. This paper describes the determination of total dissolved selenium in wastewater from selected coal-fired power plants and river waters near coal-fired power plants in South Africa. A sensitive and robust inductively coupled plasma mass spectrometry (ICP-MS) method for determining total dissolved selenium in wastewater and river water was developed using a certified reference material (NIST SRM 1640a Trace Elements in Natural Water). The results agreed with the certified values, with percentage recoveries ranging from 92–96%. The method detection limit was 0.13 µg/L. Total Se concentrations in wastewater samples from Kriel and Lethabo Power Stations ranged between 4.86 and 8.53 µg/L, and in river water samples from the Olifants and Wilge Rivers, the concentrations ranged from 2.63–8.20 µg/L. These results indicate that the Se levels in the wastewater are too low to pose a health hazard to humans and livestock but pose an environmental threat to aquatic life. The low concentrations in the river samples also show that there may be slight Se pollution (regarding aquatic life) from the selected coal-fired power plants in South Africa. There may be slight Se pollution (with regards to aquatic life) from Duvha and Kendal Power Stations because an increase from 2–8 µg/L was observed in river water samples collected near these selected coal-fired power plants.

Comparison of Selenium Accumulation in Edible Parts of Wheat and Broad Bean

The concentration of selenium (Se) in agricultural products primarily depends on the concentration of Se in soil and the ability of plants to accumulate Se. Selenium deficiency not only leads to decreased body resistance, but also increases the risk of cancer. The form and concentration of bioavailable Se is important for diet. The present study was carried out via field experiment with wheat and broad beans in soil of different Se concentrations (0, 1.12, and 11.2 kg·ha−1), which was determined based on the national standard and the team’s previous experience. Results indicated that the concentration of Se in the edible organs of wheat was higher than in broad bean, while the enriched Se concentration in the root of broad bean was more than twice and three times higher than that of wheat at medium and high levels of Se, respectively. Selenomethionine, which accounted for over half of the total Se speciations, was the dominant species in the edible parts of the two crops, followed by Selenocystine and methylselenocysteine. Through the analysis of the rhizosphere soil, it was found that Fe-Mn oxide-bound Se exceeded 80% of the total Se. Additionally, there was a significant linear correlation between the Se content in the edible parts of the two crops and the Se content in the soil. Findings suggested that wheat was more favorable than broad beans as Se supplement crops in a Se-supplied field.

Aloe Vera Extract Gel-Biosynthesized Selenium Nanoparticles Enhance Disease Resistance in Lettuce by Modulating the Metabolite Profile and Bacterial Endophytes Composition.

The use of nanotechnology to suppress crop diseases has attracted significant attention in agriculture. The present study investigated the antifungal mechanism by which aloe vera extract gel-biosynthesized (AVGE) selenium nanoparticles (Se NPs) suppressed Fusarium-induced wilt disease in lettuce (Lactuca sativa). AVGE Se NPs were synthesized by utilizing sodium selenite as a Se source and AVGE as a biocompatible capping and reducing agent. Over 21 d, 2.75% of total AVGE Se NPs was dissolved into Se ions, which was more than 8-fold greater than that of bare Se NPs (0.34%). Upon exposure to soil applied AVGE Se NPs at 50 mg/kg, fresh shoot biomass was significantly increased by 61.6 and 27.8% over the infected control and bare Se NPs, respectively. As compared to the infected control, the shoot levels of citrate, isocitrate, succinate, malate, and 2-oxo-glutarate were significantly upregulated by 0.5-3-fold as affected by both Se NPs. In addition, AVGE Se NPs significantly increased the shoot level of khelmarin D, a type of coumarin, by 4.40- and 0.71-fold over infected controls and bare Se NPs, respectively. Additionally, AVGE Se NPs showed greater upregulation of jasmonic acid and downregulation of abscisic acid content relative to bare Se NPs in diseased shoots. Moreover, the diversity of bacterial endophytes was significantly increased by AVGE Se NPs, with the values of Shannon index 40.2 and 9.16% greater over the infected control and bare Se NPs. Collectively, these findings highlight the significant potential of AVGE Se NPs as an effective and biocompatible strategy for nanoenabled sustainable crop protection.

Selenium application during fruit development can effectively inhibit browning of fresh-cut apples by enhancing antioxidant capacity and suppressing polyphenol oxidase activity

Browning is a crucial factor affecting the quality of fresh-cut apples. A safe, simple, and effective method to inhibit browning is urgently needed in fresh-cut apple production. We carried out this study to explore the effect mechanism of exogenous selenium (Se) fertilizer on fresh-cut apple browning. During the development of apples, 0.75 kg/plant Se fertilizer was exerted on the ‘Fuji’ apple tree at the critical stage of the young fruit stage (late May), early fruit expansion stage (late June), and fruit expansion stage (late July), an equal amount of Se-free organic fertilizer was used as control. Polyphenol oxidase (PPO), peroxidase (POD), and phenylalanine ammonia-lyase (PAL) activities, phenolic and malondialdehyde (MDA) content, antioxidant enzymes activity, and DPPH free radical scavenging rate of the apple at different development stages were investigated. The highest Se accumulation efficiency was observed in apple fruit one month after applying Se fertilizer, which was 41.1%. Se-rich apples exhibited a more remarkable ability to resist browning than control after fresh-cut. The anti-browning effect of the fertilization group (M7) was the best, the PPO activity decreased to 0.5 × 103 U kg−1, and the browning index was 28.6. The total Se content (TSC) of 331.4 μg kg−1 DW and organic Se content (OSC) of 292.0 μg kg−1 DW were the highest in the apple samples, reached the classification standard of Se content in Se-rich food. The correlation analysis found that fresh-cut apple browning was closely related to antioxidant capacity and PPO activity. The stronger the antioxidant capacity of fresh-cut apples treated with Se fertilizer, the lower their browning degree. Therefore, exogenous Se can alleviate fresh-cut apples browning by improving antioxidant capacity and reducing PPO activity. Se-rich apples could increase the Se content of the human essential trace element and inhibit the browning of fresh-cut apples, which would become a new, safe and effective way to solve the fresh-cut apples browning.

Effects of SeNPs Fertilizer on Se and Microelement Contents, Eating and Cooking Qualities, and Volatile Organic Compounds in Rice Grains

Foliar application of selenium (Se) fertilizer has been widely used in the production of Se-rich rice. However, the effect of Se-nanoparticles (SeNPs) fertilizer on rice quality remains largely unknown. Two bioSeNPs fertilizers were applied at different Se concentrations to explore the effect of the foliar application of SeNPs fertilizer on various rice grain qualities. The results showed that Se treatments resulted in 1.93–9.09 and 1.89–7.73 folds of total Se contents in brown and polished rice relative to the CK, respectively. Moreover, the Se treatments led to 1.04–2.33 folds increases in Cd contents, 14.6–26.4% decreases in As contents, a 13.9–16.7% reduction in Cr contents and no changes in Pb contents to that of the CK in rice grains. In addition, SeNPs exhibited no obvious impact on rice eating and cooking quality, and only the XY1 treatment could slightly improve the fatty acid content. Interestingly, Se treatments enhanced the contents of more than half of volatile organic compounds in brown rice. In general, SeNPs fertilizer XY at 6.4 g/ha was identified as the optimum choice for improvement in grain Se contents and grain qualities.

Autoantibodies to selenoprotein P in chronic fatigue syndrome suggest selenium transport impairment and acquired resistance to thyroid hormone

Chronic Fatigue Syndrome (CFS) presents with symptoms of hypothyroidism, including mental and physical fatigue, poor sleep, depression, and anxiety. However, thyroid hormone (TH) profiles of elevated thyrotropin and low thyroxine (T4) are not consistently observed. Recently, autoantibodies to the Se transporter SELENOP (SELENOP-aAb) have been identified in Hashimoto's thyroiditis and shown to impair selenoprotein expression. We hypothesized that SELENOP-aAb are prevalent in CFS, and associate with reduced selenoprotein expression and impaired TH deiodination.Se status and SELENOP-aAb prevalence was compared by combining European CFS patients (n = 167) and healthy controls (n = 545) from different sources. The biomarkers total Se, glutathione peroxidase (GPx3) and SELENOP showed linear correlations across the samples without reaching saturation, indicative of Se deficiency. SELENOP-aAb prevalence was 9.6–15.6% in CFS versus 0.9–2.0% in controls, depending on cut-off for positivity. The linear correlation between Se and GPx3 activity was absent in SELENOP-aAb positive patients, suggesting impaired Se supply of kidney. A subgroup of paired control (n = 119) and CSF (n = 111) patients had been characterized for TH and biochemical parameters before. Within this subgroup, SELENOP-aAb positive patients displayed particularly low deiodinase activity (SPINA-GD index), free T3 levels, total T3 to total T4 (TT3/TT4) and free T3 to free T4 (FT3/FT4) ratios. In 24 h urine, iodine concentrations were significantly lower in SELENOP-aAb positive than in SELENOP-aAb negative patients or controls (median (IQR); 43.2 (16.0) vs. 58.9 (45.2) vs. 89.0 (54.9) μg/L). The data indicate that SELENOP-aAb associate with low deiodination rate and reduced activation of TH to active T3.We conclude that a subset of CFS patients express SELENOP-aAb that disturb Se transport and reduce selenoprotein expression in target tissues. Hereby, TH activation decreases as an acquired condition not reflected by thyrotropin and T4 in blood. This hypothesis opens new diagnostic and therapeutic options for SELENOP-aAb positive CFS, but requires clinical evidence from intervention trials.

Phosphoramidic acid functionalized silica microspheres for simultaneous removal of Cr(VI), As(V) and Se(VI) from aqueous solutions based on molecular geometry match

The phosphoramidic acid functionalized silica (SiO2@NH2@H2PO3) were successfully synthesized to remove chromate (Cr(VI)), arsenate (As(V)), and selenate (Se(VI)) from aqueous solutions based on the molecular geometry of phosphoramidic acid is complementary to the target oxoanions shape and coordination geometry. The adsorption equilibration can be reached within 10 min. The maximum adsorption capacities of Cr(VI), As(V), and Se(VI) by SiO2@NH2@H2PO3 were 29.7, 25.6, and 38.8 mg/g, respectively. SiO2@NH2@H2PO3 is capable of removing Cr(VI), As(V) and Se(VI) in source water from 1 mg/L to 35, 584, and 94 μg/L, where the residual of Cr(VI) and Se(VI) was well below the discharge standard of total Cr and Se (< 100 μg/L) for municipal wastewater treatment plant in China. The reusability test showed that SiO2@NH2@H2PO3 can be successfully regenerated and reused. The analysis of pH effect, FT-IR and X-ray photoelectron spectroscopy demonstrated that removal of Cr(VI) and Se(VI) was mainly attributed to the formation of OP-O-Cr and OP-O-Se. The removal of As(V) was mainly ascribed to the formation of hydrogen bond with As(V). These results indicated that SiO2@NH2@H2PO3 could be a promising adsorbent in removal of Cr(VI) and Se(VI) from aqueous solutions, and the relatively low removal of As(V) warranting further design of adsorbents are needed.