Loss Of Selenium Research Articles

A First-Time Addition of Selenium to a Mg-Based Metal Matrix Composite for Biomedical Purposes

A magnesium-based metal matrix composite, Mg-5Se-2Zn-2SiO2, was synthesized using the Disintegrated Melt Deposition (DMD) method followed by hot extrusion. Elemental analysis revealed that the material experienced selenium loss which was attributed to the evaporation of selenium at high temperatures. Superior damping characteristics were exhibited while retaining similar Young’s modulus, and significant grain refinement also resulted in decisively superior mechanical properties such as hardness (32% increase), fracture strain (39% increase), as well as yield and ultimate compressive strength (157% and 54% increase, respectively). These were a consequence of SiO2 addition as well as presence of Mg2Si (and MgSe) intermetallic phases which were detected by X-ray characterization. Furthermore, while the material had lower corrosion resistance than pure magnesium, it retained acceptable corrosion resistance as well as structural integrity after the full immersion duration of 28 days. Overall, the material exhibits promising potential for applications in the biomedical field, especially in development of smaller and lighter implants where mechanical properties are paramount, with key lessons learned for the synthesis of Mg-materials containing selenium for the future.

Selenium loss during boiling processes and its bioaccessibility in different crops: Estimated daily intake

Food crops provide a good selenium (Se) source for Se-deficient populations. This study assessed how boiling affects Se concentration, speciation, and bioaccessibility in common food crops to determine human Se intake. Boiling rice resulted in an 11.9% decrease in minimum Se content, while sorghum experienced a maximum (34.9%) reduction. Boiled vegetables showed a 21% – 40% Se loss. Cereals showed notable decreases in selenomethionine (SeMet) and selenocysteine (SeCys2), while most vegetables exhibited a significant reduction in Se-methylselenocysteine (SeMeCys). Boiling significantly reduced the Se bioaccessibility in all food crops, except cabbage and potato. Cereal crops were more efficacious in meeting the recommended daily intake (RDI) of Se compared to vegetables. Rice exceeds other crops and provides up to 39.2% of the WHO/FAO-recommended target minimum daily intake of 60 μg/day. This study provides insight into a substantial dissonance between the estimated daily intake (EDI) of Se and the bioaccessible Se in both raw and boiled crops. Consequently, revising EDI standards is imperative.

Selenosalicylate; a little-studied heavy-element analogue of the versatile thiosalicylate ligand.

Selenosalicylic acid (ortho-HSeC6H4CO2H), the heavy element congener of the widely studied thiosalicylic acid, was prepared by reaction of 2-carboxybenzenediazonium chloride (HO2CC6H4N2+Cl-) with Na2Se2, followed by reduction of the resulting diselenide (SeC6H4CO2H)2 with zinc and acetic acid. The coordination chemistry of the selenosalicylate ligand towards a variety of platinum(ii), palladium(ii), nickel(ii), gold(iii), gold(i), rhodium(iii), iridium(iii) and ruthenium(ii) centres was explored. X-ray crystal structure determinations were carried out on the complexes [Pt(SeC6H4CO2)(PPh3)2], [{(p-cym)Ru(SeC6H4CO2)}2] (p-cym = η6-p-cymene, CH3C6H4CH(CH3)2), [{Cp*Rh(SeC6H4CO2)}2] (Cp* = η5-C5Me5) and [Cp*Ir(SeC6H4CO2)(PPh3)], and comparisons are made with corresponding thiosalicylate complexes. The complexes were characterised by NMR spectroscopy as well as ESI mass spectrometry, which indicated a greater propensity for fragmentation including by selenium loss, compared to the thiosalicylate analogues. Hirshfeld surface analysis to visualise and quantify intermolecular interactions revealed the dominance of H⋯H contacts in [{(p-cym)Ru(SeC6H4CO2)}2] and [Cp*Ir(SeC6H4CO2)(PPh3)].

Emerging investigator series: predicted losses of sulfur and selenium in european soils using machine learning: a call for prudent model interrogation and selection.

Reductions in sulfur (S) atmospheric deposition in recent decades have been attributed to S deficiencies in crops. Similarly, global soil selenium (Se) concentrations were predicted to drop, particularly in Europe, due to increases in leaching attributed to increases in aridity. Given its international importance in agriculture, reductions of essential elements, including S and Se, in European soils could have important impacts on nutrition and human health. Our objectives were to model current soil S and Se levels in Europe and predict concentration changes for the 21st century. We interrogated four machine-learning (ML) techniques, but after critical evaluation, only outputs for linear support vector regression (Lin-SVR) models for S and Se and the multilayer perceptron model (MLP) for Se were consistent with known mechanisms reported in literature. Other models exhibited overfitting even when differences in training and testing performance were low or non-existent. Furthermore, our results highlight that similarly performing models based on RMSE or R2 can lead to drastically different predictions and conclusions, thus highlighting the need to interrogate machine learning models and to ensure they are consistent with known mechanisms reported in the literature. Both elements exhibited similar spatial patterns with predicted gains in Scandinavia versus losses in the central and Mediterranean regions of Europe, respectively, by the end of the 21st century for an extreme climate scenario. The median change was -5.5% for S (Lin-SVR) and -3.5% (MLP) and -4.0% (Lin-SVR) for Se. For both elements, modeled losses were driven by decreases in soil organic carbon, S and Se atmospheric deposition, and gains were driven by increases in evapotranspiration.

Electrical, dielectric, and ferroelectric characteristics of Bi4Ti2.9Se0.1O12

The current communication addresses structural, impedance, conductivity, dielectric permittivity, tangent loss, and ferroelectric hysteresis of selenium doped bismuth titanate (Bi4Ti2.9Se0.1O12) synthesized by a solid-state reaction technique. XRD profile reveals the formation of orthorhombic unit cell structure (B2ab space group) in Bi4Ti2.9Se0.1O12. Partial doping of Se (10%) makes significant modifications in the electrical and dielectric characteristics, which are investigated over discrete frequencies (1 kHz–1 MHz) and temperatures (27–300 °C). The compound exhibits comparatively low value of the tangent loss at 1 MHz frequency. The ferroelectric hysteresis loop of the compound confirms the non-centrosymmetric arrangement of elements at room temperature, and the value of remanent polarization makes the compound suitable for memory applications.

Ultrasensitive determination of selenium in food samples and its speciation in water and beverages using thiosemicarbazide-incorporated graphene and total-reflection X-ray fluorescence spectrometry

The paper presents a new analytical procedure for the determination and speciation of trace and ultratrace selenium in water, beverages, seafood, milk, and vegetables. The developed method is based on the dispersive micro-solid phase extraction with the use of new thiosemicarbazide-incorporated graphene as a solid sorbent, in combination of the total-reflection X-ray fluorescence spectrometry (TXRF). As a result, we have created an auspicious analytical tool for fast and sensitive analysis of samples with a complex matrix. Regardless of the specimen type, the method is characterized by a very low detection limit of 1.7 pg mL−1 and high precision. The developed strategy allowed us to solve common problems associated with selenium loss during the sample preparation for the TXRF measurement and also improve its performance toward the analysis of beverages and high saline/solid samples, which may even be impossible to perform using standard sample preparation procedures for a TXRF measurement.

Is anti-IgE therapy effective in preventing magnesium and selenium loss in bones of mice with chronic allergic asthma?

Objective: Chronic allergic asthma (CA) is a respiratory disease that affects millions of people worldwide. While there is evidence linking airway hyperresponsiveness and asthma to factors related to bone metabolism, the impact of asthma on bone health is not well understood. Therefore, to explore whether: (i) CA causes meaningful changes in bone magnesium (Mg) and selenium (Se) levels, and if any, (ii) anti-IgE (anti-immunoglobulin E) treatment has a protective effect against these changes.
 Methods: In present study used tibia bones from a previous study on CA in mice. A murine model was used to generate CA. Thirty-two BALB/c male mice were randomly divided into four equal sized groups (eight mice/group): control group (intact), CA (treated with saline (0.9% NaCl), CA+L-AIgE (100 μg of anti-IgE), CA+H-AIgE (200 μg of anti-IgE). After immunization, saline was administered by inhalation three times a week. Anti-IgE applications were performed intraperitoneally for a total of 8 weeks in five sessions with 15-day intervals. Bone Mg and Se levels are determined by inductively coupled plasma mass spectrometry (ICP-MS), which is used to determine the elemental composition of various samples.
 Results: Mg levels of CA and CA+L-AIgE groups were significantly decreased compared to the control (P

Effect of Vacuum Roasting on Total Selenium Content of Selenium-Enriched Rapeseed, Maillard Reaction Products, Oxidative Stability and Physicochemical Properties of Selenium-Enriched Rapeseed Oil.

Selenium-enriched rapeseed (SER) is an emerging oil seed. Roasting is beneficial in improving oil yield and promoting the release of micronutrients into SER oil, but high temperatures and dry air lead to selenium loss and fatty acid degradation in SER. To minimize the selenium loss and improve the SER oil quality, this study investigated the effects of vacuum (VC) roasting (90-170 °C for 30 min) on the SER selenium content, Maillard reaction products, oxidative stability, and physicochemical properties of SER oil, with conventional dry air (DA) roasting as the control. The results showed that the selenium loss in VC-roasted SER meals increased from 7.17 to 19.76% (90-170 °C for 30 min), which was 47.13 to 80.48% of that in DA-roasted SER meals, while no selenium was detected in the SER oils. Compared to DA roasting, VC roasting (90-170 °C for 30 min) reduced lipid oxidation products (LOPs), Maillard reaction products (MRPs), and benzo[a]pyrene contents, and increased carotenoids, unsaturated fatty acid contents, reaching a maximum oil yield of 35.58% at a lower temperature (130 °C for 30 min). Selenium contents exhibited a highly significant negative correlation with MRPs and LOPs (p ≤ 0.005). The VC roasting retarded selenium loss and improved SER oil quality compared to conventional DA roasting.

Loss of Selenium from Mollisol Paddy Wetlands of Cold Regions: Insights from Flow-through Reactor Experiments and Process-Based Modeling

Mollisols are critical agricultural resources for securing global food supply. Due to its health importance, selenium (Se) fate in the Mollisols attracts growing concerns. Land use change from conventional drylands to paddy wetlands impacts Se bioavailability in the vulnerable Mollisol agroecosystems. The underlying processes and mechanisms however remain elusive. Here, results of flow-through reactor experiments with paddy Mollisols from northern cold-region sites indicate that continuous flooding with surface water for 48 d induced redox zonation that facilitated the loss of Mollisol Se by up to 51%. Further process-based biogeochemical modeling suggests largest degradation rates of dissolved organic matter (DOM) in 30 cm deep Mollisols that contained the highest-level labile DOM and organic-bound Se. Electron shunting from degradation of Se-bearing DOM coupled to reductive dissolution of Se-adsorbed Fe oxides accounts mainly for Se(IV) release into the pore water. Consequent changes in DOM molecular composition make the reservoir of organic-bound Se vulnerable to flooding-induced redox zonation and likely enhance Se loss through destruction of thiolated Se and emission of gaseous Se from the Mollisol layer. This study highlights a neglected scenario where the speciation-driven loss of bioavailable Se from the paddy wetlands can be a significant consequence in the cold-region Mollisol agroecosystems.

Effects of Different Drying Methods on the Selenium Bioaccessibility and Antioxidant Activity of Cardamine violifolia

Understanding the effects of drying on the selenium (Se) content and Se bioaccessibility of Se-rich plants is critical to dietary supplementation of Se. The effects of five common drying methods (far-infrared drying (FIRD), vacuum drying (VD), microwave vacuum drying (MVD), hot air drying (HD), and freeze vacuum drying (FD)) on the content and bioaccessibility of Se and Se species in Cardamine violifolia leaves (CVLs) were studied. The content of SeCys2 in fresh CVLs was the highest (5060.50 μg/g of dry weight (DW)); after FIRD, it had the lowest selenium loss, with a loss rate of less than 19%. Among all of the drying processes, FD and VD samples had the lowest Se retention and bioaccessibility. FIRD, VD, and FD samples have similar effects on antioxidant activity.

Computer customization errors compromised the optimization of trace element repletion dose after major burns

Major burns develop acute trace element (TE) deficiencies due to exudative losses of copper, selenium, and zinc from the wounds. A repletion strategy has been shown to decrease infectious and surgical complications. The TE doses have been adapted over time and the last adaptation, was not followed by the expected changes. The study aims at identifying the causes of the failure. Retrospective cohort study including critically ill major burns patients admitted to intensive care with burns exceeding 20% of body surface area (BSA). Period A (2011-2015) included patients admitted before the dose change, and Period B patients after (2017-2020). Demographic variables, daily TE delivery, and weekly TE blood levels were extracted from the computerized information system (CIS). Altogether 71 patients completed the inclusion criteria (Periods A and B: 42 and 29 patients respectively). They were aged 38 (32) years and burned 35 (30) % BSA, with no severity differences. Comparing periods A and B, copper (p=0.046) and selenium (p=0.031) blood levels were significantly lower in B. The dose value extracted from CIS was as planned. Customization error was found: TE salts' weight had been entered instead of elemental weight in molar units. The lower TE repletion doses administered since 2017 resulted in a significant decrease in blood levels of Cu and Se. A CIS customisation error, confusing salt weight and elemental weight was the source of the error. A systematic quality control is crucial to identify systemic errors, as is the use of the standard international units.

Sample preparation induced phase transitions in solution deposited copper selenide thin films.

Thin films of CuSe were deposited onto GaAs substrate. XRD showed that the as-deposited films were of the Klockmannite (CuSe – P63/mmc 194) phase with lattice parameters a0 = b0 = 0.3939 nm, c0 = 1.7250 nm; however, electron diffraction in the TEM surprisingly indicated the β-Cu2−xSe phase (Cu1.95Se – R3̄m 166) with lattice parameters a0 = b0 = 0.412 nm, c0 = 2.045 nm. The discrepancy originated from the specimen preparation method, where the energy of the focused ion beam resulted in loss of selenium which drives a phase transition to β-Cu2−xSe in this system. The same phase transition was observed also upon thermal treatment in vacuum, as well as when the 200 keV electron beam was focused on a powder sample in the TEM. The initial phase can be controlled to some extent by changing the composition of the reactants in solution, resulting in thin films of the cubic α-Cu2−xSe (Cu1.95Se – Fm3̄m) phase co-existing together with the β-Cu2−xSe phase.

Dopaminergic Neuronal Death in Substantia Nigra Associates with Serum Levels of Total Bilirubin, Selenium, and Zinc: Evidences from 6-Hydroxydopamine Animal Model of Parkinson's Disease.

Mild to moderate dopaminergic (DA) neuronal death in substantia nigra pars compacta (SNc) as the main pathological hallmark of Parkinson's disease (PD) is usually silent and does not produce marked clinical symptoms. In this study, we investigated the association between SNc DA neuronal loss and serum levels of total bilirubin (TB), selenium (Se), and zinc (Zn) in 6-hydroxydopamine (6-OHDA) animal model of PD. The neurotoxin of 6-OHDA was injected into the medial forebrain bundle of right hemisphere by stereotaxic surgery. Two conventional behavioral tests were carried out in several steps after the toxin to confirm the model reproduction and quantify severity and progress of 6-OHDA-induced PD. Blood samples were collected within 1week before the toxin and in the second, fifth, and eighth weeks thereafter. Immunohistochemistry (IHC) assessments were performed on the rat's brain to determine the severity of DA neuronal loss in SNc. The severity of behavioral symptoms and TB levels were progressively increased in 6-OHDA-treated rats. On the other hand, Se and Zn levels in them were lower than control. These changes were observed in rats with severe or mild behavioral symptoms. Also, IHC revealed that changes in TB, Se, and Zn associate with SNc DA neuronal loss but do not correlate with its severity. Significant changes in serum levels of TB, Se, and Zn in the mild SNc DA neuronal loss suggest them as valuable parameters for establishment of a serum profile for early detection of PD.

Effect of boiling and frying on the selenium content, speciation, and in vitro bioaccessibility of selenium-biofortified potato (Solanum tuberosum L.)

Selenium-enriched potato is a good supplement for selenium-deficient populations. This study evaluated the influence of two most common cooking methods, including boiling and frying, on selenium content, speciation, and in vitro bioaccessibility of selenium-biofortified potato tubers. After foliar application of 200 μg/mL sodium selenite, potato tubers with 1.33 μg Se/g were obtained. Peeling resulted in 53.4%–69.9% loss of selenium in tubers. The total selenium content decreased by approximately 43.3% after boiling, among which up to 38.5% of the lost selenium is found in the boiling water. Nearly 31.7% of selenium was lost via volatilization during frying. Both cooking methods significantly enhanced the bioaccessibility of Se(IV) in tubers. Whereas SeMeCys became less bioaccessible after boiling. SeMet and SeCys2 in fired tubers were not accessible after digestion. This study suggested that boiling is more appropriate for cooking selenium-enriched potatoes.

Selenium loss and changes in product quality during cooking of selenium enriched potato tubers

Selenium biofortification is increasingly applied to improve selenium contents in the edible parts of crops. Potato (Solanum tuberosum L.) is a major food crop with wide availability of consumption, which is suitable for selenium biofortification. However, the processing and product quality of selenium-enriched potatoes has rarely been reported. Herein, selenium-enriched potato tubers (0.24 mg kg−1 fresh weight) were used to investigate selenium retention, loss details, and quality changes in different processed products. Final selenium contents of the products varied with different processing methods (P <0.01). Compared to fresh tubers, steaming resulted in the lowest loss rate of selenium (28.64 %), mainly related to decoction. Moderate loss rates of selenium were recorded in boiled tubers (42.44 %), French fries (44.73 %), and crisps (50.86 %), mainly related to decoction, cutting and hot cleaning, respectively. The highest loss rate was attributed to starch extraction (98.69 %), mainly related to crude protein. Selenium application delayed enzymatic discoloration of fresh-cut tubers (P < 0.05) and increased the proportion of large- to medium-sized starch granules (>30 μm) (P < 0.05) compared to the control. To minimize selenium loss, steaming is superior to boiling and frying for the processing of selenium-enriched potatoes, and it is not feasible to produce selenium-enriched starch.

Sorption of Se (IV) from aqueous solutions with subsequent determination by X-ray fluorescence analysis

An approach to sorptive separation of Se (IV) from solutions on a novel S,N-containing sorbent with subsequent determination of the analyte in the sorbent phase by micro-x-ray fluorescence method is presented. The sorbent copolymethylenesulfide-N-alkyl-methylenamine (CMA) was synthesized using «snake in the cage» procedure and proven to be stable in acid solutions. Conditions for quantitative extraction of Se (IV) were determined: sorption in 5 M HCl or 0.05 M HNO3 solutions when heated to 60°C, phase contact time being 1 h. The residual selenium content in the solution was determined by inductively coupled plasma mass spectrometry (ICP-MS) using 82Se isotope. The absence of selenium losses is proved and the mechanism of sorption interaction under specified conditions is proposed. The method of micro-x-ray fluorescence analysis (micro-RFA) with mapping revealed a uniform distribution of selenium on the sorbent surface. The possibility of determining selenium in the sorbent phase by micro-RFA is shown. When comparing the obtained results with the results of calculations by the method of fundamental parameters, it is shown the necessity of using standard samples of sorbates to obtain correct results of RFA determination of selenium in the sorbent phase.

Can Selenoenzymes Resist Electrophilic Modification? Evidence from Thioredoxin Reductase and a Mutant Containing α-Methylselenocysteine.

Selenocysteine (Sec) is the 21st proteogenic amino acid in the genetic code. Incorporation of Sec into proteins is a complex and bioenergetically costly process that evokes the following question: "Why did nature choose selenium?" An answer that has emerged over the past decade is that Sec confers resistance to irreversible oxidative inactivation by reactive oxygen species. Here, we explore the question of whether this concept can be broadened to include resistance to reactive electrophilic species (RES) because oxygen and related compounds are merely a subset of RES. To test this hypothesis, we inactivated mammalian thioredoxin reductase (Sec-TrxR), a mutant containing α-methylselenocysteine [(αMe)Sec-TrxR], and a cysteine ortholog TrxR (Cys-TrxR) with various electrophiles, including acrolein, 4-hydroxynonenal, and curcumin. Our results show that the acrolein-inactivated Sec-TrxR and the (αMe)Sec-TrxR mutant could regain 25% and 30% activity, respectively, when incubated with 2 mM H2O2 and 5 mM imidazole. In contrast, Cys-TrxR did not regain activity under the same conditions. We posit that Sec enzymes can undergo a repair process via β-syn selenoxide elimination that ejects the electrophile, leaving the enzyme in the oxidized selenosulfide state. (αMe)Sec-TrxR was created by incorporating the non-natural amino acid (αMe)Sec into TrxR by semisynthesis and allowed for rigorous testing of our hypothesis. This Sec derivative enables higher resistance to both oxidative and electrophilic inactivation because it lacks a backbone Cα-H, which prevents loss of selenium through the formation of dehydroalanine. This is the first time this unique amino acid has been incorporated into an enzyme and is an example of state-of-the-art protein engineering.

Содержание селена в макаронных изделиях на основе полбяной и гречневой муки, а также овощных порошков

Introduction. As a trace element, selenium is present in humans as part of selenoproteins. It improves the work of the antioxidant defense system and produces a strong immunomodulatory effect. Selenium is part of about 30 biologically active compounds of human body. However, selenium deficiency is considered a global problem. The research objective was to determine the selenium content in the developed pasta products. Study objects and methods. The study featured laboratory samples of pasta made from a mix of whole wheat spelt flour, buckwheat, and low-temperature drying powders of broccoli and celery. The selenium content was determined by atomic absorption spectroscopy with electrothermal atomization with a palladium nitric acid matrix modifier. The experiment employed a Hitachi 180-80 atomic absorption spectrophotometer. To determine the selenium content, the samples underwent wet mineralization in nitric and perchloric acids. Adding hydrogen peroxide and ethanol made it possible to convert selenium from inorganic and organic forms into selenite ions. Results and discussion. The research involved domestic natural raw materials. The components proved to be good sources of selenium, which means that they can be used to produce functional products. The selenium content ranged from 105.7 ± 22 mkg/kg to 302.5 ± 17 mkg/kg in the samples. Taking into account the loss of selenium during cooking, the selenium content in 100 g of the finished product ranged from 13.5% to 38.5 %. Conclusion. The developed pasta products proved excellent sources of selenium. The use of buckwheat flour and vegetable powders in the formulation of wholegrain spelt dough increased the selenium content in the pasta by 40.7–186.2 %. The obtained results can be used for tables of the chemical composition of Russian food products.

Compositional Phase Change of Early Transition Metal Diselenide (VSe2 and TiSe2) Ultrathin Films by Postgrowth Annealing

AbstractThe transition metal selenides M1+ySe2 (M = V, Ti) have intriguing quantum properties, which make them target materials for controlling properties by thinning them to the ultrathin limit. An appropriate approach for the synthesis of such ultrathin films is by molecular beam epitaxy. Here, it is shown that such synthesized V‐ and Ti‐Se2 films can undergo a compositional change by vacuum annealing. Combined scanning tunneling and photoemission spectroscopy is used to determine compositional and structural changes of ultrathin films as a function of annealing temperature. Loss of selenium from the film is accompanied by a morphology change of monolayer height islands to predominantly bilayer height. In addition, crystal periodicity and atomic structure changes are observed. These changes are consistent with a transition from a layered transition metal dichalcogenide (TMDC) to ordered intercalation compounds with V or Ti intercalated in between two layers of their respective TMDCs. These observations may clear up misconception of the nature of previously reported high‐temperature grown transition metal selenides. More significantly, the demonstrated control of the formation of intercalation compounds is a key step toward modifying properties in van der Waals systems and toward expanding material systems for van der Waals heterostructures.

Selenium in Se-enriched tartary buckwheat (Fagopyrum tataricum L. Gaertn.): Its molecular form and changes during processing

The essential trace mineral, selenium (Se), is of fundamental importance to human health. Tartary buckwheat is a pseudocereal variety rich in functional flavonoids. To investigate the characters of Se-enriched Tartary buckwheat in Shaanxi province, we studied effect of different processing methods on its nutrients and selenium distribution in Se-enriched buckwheat groat (Se-BG), milled flour (Se-BMF), extruded flake (Se-BEF) and roasted groat (Se-BRG). The highest total selenium content in Se-BG was 118.04 μg/kg. Se-BMF (110.55 μg/kg) and Se-BEF (98.55 μg/kg) showed less selenium loss while the most selenium loss was recorded in Se-BRG (66.63 μg/kg). Selenium and selenomethionine (SeMet) were mainly present in glutelin, followed by albumin. SeMet content followed the trends of Se-BG (76.21 μg/kg groat) > Se-BMF (75.24 μg/kg groat) > Se-BEF (64.76 μg/kg groat) > Se-BRG (21.21 μg/kg groat).This shows that processing also has a great influence on the distribution of selenium forms.