Initial Se Research Articles

090 Effects of Se-fortified Hay Feeding During the Periparturient Period on Measures of Se Status in Cows and Calves

The objective of this study was to evaluate the effect of supplemental Se source during the periparturient, on Se status of cows and calves. 27 mature cows were randomly assigned to the follow treatments; no Se (Control; n = 6), Na selenite (n = 9) or High-Se hay (n = 12). Cows assigned to the Na selenite and High-Se hay treatments were provided 2.5 mg of supplemental Se daily. High-Se hay was created by biofortification of ‘Jiggs’ bermudagrass (Cynodon dactylon L.) hayfields. Briefly, Na selenate (8.8 g/L) was dissolved into water and sprayed onto hayfields at a rate of 257 g Se/ha at 8 weeks prior of harvest. Selenium concentration of hay harvested from Na selenate-treated fields was greater (P < 0.001) than fields without Na selenate treatment (10.8 vs. 0.1 mg Se/kg DM). Cows were moved into partially covered individual feeding areas at an estimated 30 d prior to calving (actual days on treatment = 29.07, 32.60, and 23.83 for high-Se hay, Na selenite, and Control treatments, respectively; SEM = 6.45). Cows calving sooner than 10 d on treatment were removed from the study, which resulted in an unequal number of cows enrolled among treatments. Initial cow Se status was determined by blood and liver samples collected on d 0 (study enrollment). Placenta was collected at calving for determination of Se concentration of cotyledons. Four days after calving, blood and liver samples were collected from both cows and calves for determination of Se status. Initial liver Se concentrations were used as a covariate for analyses. Selenium-supplemented cows had greater (P < 0.0001) liver Se concentrations on d 4 after calving compared to Control and cows provided supplemental Se via High-Se hay tended (P = 0.11) to have greater liver Se concentrations compared to cows provided Na selenite (0.60, 1.22, and 1.13 mg/kg DM for Control, High-Se hay, and Na selenite, respectively; SEM = 0.057). Similarly, Se-supplemented cows had greater (P = 0.03) cotyledon Se concentrations at calving compared to Control, but source of Se did not differ (P = 0.16; 0.69, 0.88 and 0.80 mg/kg DM for Control, High-Se hay, and Na selenite, respectively; P=0.03; SEM=0.056). Calf liver Se concentrations did not differ (P ≥ 0.58) among treatments (1.17, 1.27 and 1.21 mg/kg DM for High-Se hay, Na selenite, and Control, respectively). These data imply that Se biofortification of hayfields can increase Se status of periparturient cows.

0206: The correlation between serum selenium levels and cardiac biomarkers in patients with acute myocardial infarction

Selenium plays an important role in the antioxidant defense of myocardium both by being a part of enzyme glutathione peroxidase and operating independently. The Purpose of this research was to establish relation between serum selenium levels and the biomarkers of cardiac injury in acute phase of myocardial infarction. 42 patients with acute myocardial infarction (AMI) were examined, mean age 61.82±7.65 years; 11 women, 31 men. The amounts of troponin I (TnI, ng/mL) and creatine kinase-MB (CK-MB, U/L) were determined on admission and in 24 hours. Selenium (Se) level was measured by fluorometric method. All patients received standard therapy during first day of hospitalization. Se levels on admission and in 24 hours didn’t significantly differ (0.225±0.03µg/mL and 0.219±0.04µg/mL, respectively). Close correlation was established between initial Se levels and peak indexes of biomarkers: TnI (r=0.14, p=0.006), CK-MB (r=0.16, p=0.004). Also, a positive correlation was found between the peak amounts of biomarkers and the difference from initial to 24 h: TnI (r=0.09, p=0.031), CK-MB (r=0.07, p=0.043). At the same time, initial Se levels correlated negatively with the difference from initial to 24 h (r=–0.63, p=0.002). Se levels in acute phase of AMI closely correlate with the peak amounts of cardiac biomarkers. Therefore, the changes of Se levels may interrelate with the extent of myocardial injury during infarction.

PTH-216 Trace element measurement in hospitalised children on parenteral nutrition: Abstract PTH-216 Table 1

<h3>Introduction</h3> The aim of parenteral nutrition (PN) is to meet the body’s needs while avoiding complications of deficiency and toxicity.¹Trace elements (Cu, Zn, Se) play an important role in many of the body’s functions including metabolism, immunity and enzymes.¹ESPGHAN/ ESPEN guidelines recommended that levels of trace elements should be checked at the commencement and frequently after starting PN.¹Our aim was to review the current practice in our tertiary paediatric hospital. <h3>Method</h3> In-patients receiving PN were identified from the pharmacy database. All records from patients receiving PN on two randomly allocated days in December and January were analysed for demographic data and diagnosis. From the laboratory database we looked for Zinc (Zn), Copper (Cu) and Selenium (Se) levels at the commencement and 4–8 weeks after starting PN. We excluded patients with no available data on the start of PN. <h3>Results</h3> 72 patients receiving PN were identified on the two days. Data were available for 63 patients and 9 others were excluded as data was not available on starting PN. The 63 patients with available results were aged 1–16 years, median age of 4.5 years. 36 were males. Overall; Trace Elements (TE) were checked in 26/63 (41.2%) (Table1). TE results were available before or within one week of starting PN in 18/63 (28.5%). Thirteen had TE follow up. Table 3 shows the levels of TE within one week of starting PN and the follow up results. 5 patients had low initial Zn, Cu and Se. These were patients with Tufting enteropathy, early onset inflammatory bowel disease (IBD), one patient with IPEX, one patient with Intestinal obstruction and one with missing records. The latter two in addition to another patient with HLH also had low levels on follow up. Out of the whole cohort of 63, 27 (43%) patients have an underlying gastrointestinal disorder, 20 (74%) of whom had levels checked initially and 9 (33%) had levels done on follow up. <h3>Conclusion</h3> Unfortunately determination of TE level is frequently missed in our institution. Although figures from the gastroenterology department were better than other departments, we recommended use of a proforma to be filled by the clinician before starting PN. We recommend TE to be checked at least once every 3 months for those with normal levels and once a month for those with low levels. A re-audit is planned later in the year. <h3>Disclosure of interest</h3> None Declared. <h3>Reference</h3> Koletzko B, <i>et al</i>. J Pediatr Gastroenterol Nutr. 2005;41(Suppl 2)

Ultimate selenium(IV) monitoring and removal from water using a new class of organic ligand based composite adsorbent

This work reports the selenium (Se(IV)) detection and removal from water by ligand functionalized organic–inorganic based novel composite adsorbent. The composite adsorbent was prepared by direct immobilization of N,N′-di(3-carboxysalicylidene)-3,4-diamino-5-hydroxypyrazole onto the mesoporous silica monolith. The adsorbent exhibited distinct color change in the presence of various concentrations of Se(IV). This was characterized by UV–vis spectroscopy, and the color change was observed by naked-eye observation. The detection limit was determined to be 1.14μg/L. The effect of solution pH, interferential metal ions, contact time, initial Se(IV) concentration, and adsorbent regeneration were evaluated. The maximum sorption capacity was determined based on the initial concentration. The data fitted well to the Langmuir isotherm model, and the maximum Se(IV) sorption capacity was 111.12mg/g. The presence of diverse competing ions did not affect the Se(IV) sorption capacity, and the adsorbent had almost no sorption capacity for these coexisting ions, which suggests the high selectivity to Se(IV) ions. The adsorbed Se(IV) was eluted with suitable eluent (0.10M NaOH) and simultaneously regenerated into the initial form for the next operation. The excellent reusability of the adsorbent was justified after eight consecutive sorption–elution–regeneration cycles. The proposed adsorbent is cost-effective and environmentally friendly and a potential candidate for treatment of water containing Se(IV).

Comparison of adsorption characteristics of Se(IV) and Se(VI) onto hematite: effects of reaction time, initial concentration, pH, and ionic strength

In this study, the adsorption of selenite [Se(IV)] and selenate [Se(VI)] onto synthesized hematite is investigated under various conditions of reaction time, initial concentration, pH, and ionic strength. The adsorption of 50 µM Se(IV) and Se(VI) reaches steady-state within 5 h and 5 min, respectively, for the condition of 0.8 g/L hematite, 0.01 M NaCl and pH 5.5 ± 0.2. It is found that the parabolic diffusion model is the best to represent the adsorption kinetics of the two Se species onto hematite. On the contrary to the kinetic results, more Se(IV) is adsorbed than Se(VI) at equilibrium by approximately three times under the same physicochemical condition. The maximum adsorption capacities of Se(IV) and Se(VI) onto hematite are 4.04 × 10−6 and 1.15 × 10−6 mol/m2, respectively, for 10–400 µM initial Se species concentration, 0.8 g/L hematite, 0.01 M NaCl, and pH 5.5 ± 0.2. The Langmuir model is the best to describe the isotherm data of both Se(IV) and Se(VI) adsorption. The adsorption of both Se(IV) and Se(VI) is maximum at acidic pH, showing considerable gap of adsorption capacity between the two Se species. As pH increases, the gap decreases and at pH higher than 10 it becomes negligible. The adsorption envelope of the Se(IV) is insensitive to ionic strength but that of the Se(VI) decreases with increasing ionic strength, indicating the formation of inner-sphere complex and outer-sphere complex for Se(IV) and for Se(VI), respectively.

Removal of Se(IV) and Se(VI) from drinking water by coagulation

Selenium (Se) is one of contaminants required to be regulated during drinking water treatment, however, little information has been collected to date regarding Se removal by coagulation. In this study, the performance of Se removal by coagulation has been evaluated with respect to the dependence on Se species, coagulant type, water pH and interfering ions. The results showed that a Fe-based coagulant was much more efficient than Al-based coagulants in Se removal. The removal of selenite (Se(IV)) by coagulation was much more pronounced than that of selenate (Se(VI)). With an FC dosage of more than 0.4mMFe/L, Se(IV) removal efficiency of more than 98% could be achieved when the initial Se(IV) concentration was 250μg/L. For Al-based coagulants (AlCl3 (AC) and polyaluminum chloride (PACl)) Se removal efficiency was positively correlated with the content of Al13 species during the coagulation process. Adsorption onto hydroxide flocs was the most active coagulation mechanism for Se removal and precipitation also played specific roles at low dosage, especially for Se(IV) removal and with Fe coagulant. High coagulant dosage and weakly acidic pH could enhance the formation of hydroxide flocs having more active adsorption sites and high zeta potential, and thus favored Se removal. These findings are important to understand the efficiency and mechanisms of Se removal by coagulation.

Selenium speciation in malt, wort, and beer made from selenium-biofortified two-rowed barley grain.

Selenium (Se) biofortification of barley is a suitable strategy to increase the Se concentration in grain. In the present paper, the suitability of this Se-biofortified grain for making Se-enriched beer is analyzed. The aim of the present study was to evaluate the effect of different Se fertilizer doses (0, 10, and 20 g of Se ha(-1)) and forms (sodium selenate or sodium selenite) on the Se loss during the malting and brewing processes and Se speciation in grain, malt, wort, and beer. Samples were analyzed using inductively coupled plasma-mass spectrometry (ICP-MS) and high-performance liquid chromatography (HPLC)-ICP-MS for total Se and speciation. Mashing-lautering was the process with the greatest Se loss (83.8%). After malting and brewing, only 7.3% of the initial Se was retained in beer, mainly in selenite form. Even so, the fertilizer application of sodium selenate at 20 g ha(-1) increased the total Se concentration almost 6-fold in the final beer in comparison to the use of grain derived from unfertilized barley. The present paper provides evidence that the use of Se-biofortified barley grain as a raw material to produce Se-enriched beer is possible, and the results are comparable to other methods in terms of efficiency.

Kinetics of selenite reduction by zero-valent iron

Zero-valent iron (ZVI) is an inexpensive agent that can remove many common environmental contaminants. The effects of dissolved oxygen (DO), pH, initial selenite concentration (Se(IV)), ZVI dosage and particle size as well as reaction temperature on Se(IV) removal by ZVI were systematically investigated in this study. Se(IV) removal by ZVI was more favored under oxic conditions with higher reaction rate than under anoxic conditions, ascribing to the promoted ZVI corrosion rate in the presence of DO. Moreover, Se(IV) removal by ZVI was enhanced with increasing ZVI dosage and reaction temperature but decreased with increasing pH and ZVI particle size. The removal rate of Se(IV) by ZVI experienced an increase and then a decrease with initial Se(IV) concentration ranging from 9.9 to 78.6mg L-1. To further describe the reaction rate, a pseudo-?rst-order kinetics was employed, and the calculated activation energy, by fitting the rate constants at different temperatures, was determined to be 32.86kJmol(-1). When fixing other conditions, good linear correlation could be observed between pseudo-first-order reaction rate constants (k(obs)) and ZVI dosage. Compared with other methods for Se(IV) removal reported in literatures, reduction by ZVI was considered a promising technique, which could rapidly and effectively eliminate Se(IV) from waters.

Comparative study of Se oxyanions retention on three argillaceous rocks: Upper Toarcian (Tournemire, France), Black Shales (Tournemire, France) and Opalinus Clay (Mont Terri, Switzerland)

A comparative study of selenium oxyanion sorption was carried out by means of batch sorption experiments on three argillaceous rocks that differ in their mineralogical compositions and textural properties. The results show no selenate (Se(VI)) sorption onto the argillaceous rocks after 60 days, but clear sorption of selenite (Se(IV)), the extent being closely related to the initial Se(IV) concentration. At the lowest concentration ([Se(IV)]eq < 10−8 mol L−1), the ranking of rock affinity for Se(IV) is Black Shales > Opalinus Clay (OPA) > Upper Toarcian, with Rd values of 910 ± 70, 600 ± 65 and 470 ± 70 mL g−1 respectively. The Se(IV) sorption isotherms acquired for the three argillaceous rocks can be reproduced well by means of Langmuir formalism, particularly with a two-site Langmuir model. The comparison of the Se(IV) sorption isotherms obtained for these three rocks led to identification of pyrite associated with natural organic matter (NOM) as one of the main phases involved in selenium retention. While the desorption results suggested a significant Se(IV) reduction in the Upper Toarcian samples, the reversible sorption shown on the Black Shales and OPA samples was correlated with a sulfate increase, symptomatic of surface oxidation of pyrite which could limit the Se(IV) reduction in favor of sorption.

Weak magnetic field significantly enhances selenite removal kinetics by zero valent iron

The effect of weak magnetic field (WMF) on Se(IV) removal by zero valent iron (ZVI) was investigated as functions of pH and initial Se(IV) concentrations. The presence of WMF significantly accelerated Se(IV) removal and extended the working pH range of ZVI from 4.0–6.0 to 4.0–7.2. The WMF induced greater enhancement in Se(IV) removal by ZVI at lower initial Se(IV) concentrations. The influence of WMF on Se(IV) removal by ZVI was associated with a more dramatic drop in ORP and a more rapid release of Fe2+ compared to the case without WMF. SEM and XRD analysis revealed that WMF accelerated the corrosion of ZVI and the transformation of amorphous iron (hdyr)oxides to lepidocrocite. XANES analyses showed that WMF expedited the reduction of Se(IV) to Se(0) by ZVI at pH 6.0 when its initial concentration was ≤20.0 mg L−1. Se(IV) dosed at 40.0 mg L−1 was removed by ZVI via adsorption followed by reduction to Se(0) at pH 7.0 but via adsorption at 7.2 in the presence of WMF. Regardless of WMF, Se(IV) applied at 40.0 mg L−1 was removed by reduction at pH 4.0–6.0. The WMF-induced improvement in Se(IV) removal by ZVI may be mainly attributable to the Lorentz force and magnetic field gradient force. Employing WMF to enhance Se(IV) removal by ZVI is a promising and environmental-friendly method since it does not need extra energy and costly reagents.

Impact of treatment planning target volumen (PTV) size on radiation induced diarrhoea following selenium supplementation in gynecologic radiation oncology - a subgroup analysis of a multicenter, phase III trial

BackgroundIn a previous analysis (Int J Radiat Oncol Biol Phys 70:828-835,2010), we assessed whether an adjuvant supplementation with selenium (Se) improves Se status and reduces the radiation-induced side-effects of patients treated by adjuvant radiotherapy (RT) for cervical and uterine cancer. Now, a potential relation between the planning target volume (PTV) of the RT and the Se effect concerning radiation induced diarrhoea was evaluated in detail.MethodsWhole blood Se concentrations had been measured in patients with cervical (n=11) and uterine cancer (n=70) after surgical treatment, during, and at the end of RT. Patients with initial Se concentrations of less than 84 μg/l were categorized as Se-deficient and randomized before RT to receive Se (as sodium selenite) per os on the days of RT, or to receive no supplement during RT. Diarrhoea was graded according to the Common Toxicity Criteria system (CTC, Version 2a). The evaluation of the PTV of the RT was ascertained with the help of a specialised computer-assisted treatment planning software used for radiation planning procedure.ResultsA total of 81 patients had been randomized for the initial supplementation study, 39 of which received Se [selenium group, SeG] and 42 serving as controls [control group, CG]. Mean Se levels did not differ between SeG and CG upon study initiation, but were significantly higher in the SeG compared to the CG at the end of RT. The actuarial incidence of at least CTC 2 radiation induced diarrhoea in the SeG was 20.5% compared to 44.5% in the CG (p=0.04). The median PTV in both groups was 1302 ml (916–4608). With a PTV of <= 1302 ml (n=41) the actuarial incidence of at least CTC 2 diarrhoea in the SeG was 22.3% (4 of 18 patients) compared to 34.8% (8 of 23 patients) in the CG (p=0.50). In patients with a PTV of > 1302 ml (n=40) the actuarial incidence of at least CTC 2 diarrhoea in the SeG was 19.1% (4 of 21 patients) versus 52.6% (10 of 19 patients) in the CG (p=0.046).ConclusionsSe supplementation during RT was effective to improve blood Se status in Se-deficient cervical and uterine cancer patients, and reduces episodes and severity of RT-induced diarrhoea. This effect was most pronounced and significant in patients with large PTV (> 1302 ml).

Sorption and Desorption Processes of Selenium (VI) Using Non-Living Biomasses of Aquatic Weeds in Horizontal Flow

The sorption and desorption processes of Se(VI) onto non-living Eichhornia crassipes (E. crassipes) and Lemna minor (L. minor) were evaluated. Different pH values of the initial Se solution (20 μg L−1) were tested at static conditions. At dynamic conditions of horizontal flow, biomass-packed columns (BPC) were estimated as prepared (pH 4) and unprepared (pH 6–7) and at different flow rates. The desorption process was tested using HCl (0.1 M) as the eluent. The maximum Se uptake took place at a pH of 4 for both biomasses. The lowest flow rate improves major Se removal due to the increase in contact time. The Se was desorbed from the biomass with elution efficiencies of 5 and 18 % for E. crassipes and L. minor, respectively. Nevertheless, more time was needed to increase these efficiencies and reach desaturation times. The breakthrough curves showed that unprepared E. crassipes and L. minor BPC at horizontal flow, with a flow rate of 6 and 4 mL min−1 respectively, had a biomass removal capacity of 0.135 and 0.743 μg g−1 correspondingly. The system of E. crassipes is more efficient, suggesting an ion exchange sorption mechanism. This demonstrates that non-living E. crassipes and L. minor have the capacity to remove Se from very dilute solutions.

Effect of injectable trace minerals on the humoral immune response to multivalent vaccine administration in beef calves1

The objective of this experiment was to investigate the effects of injectable trace minerals on humoral responses of calves receiving a viral vaccination. Beef steer calves (n = 99; average BW = 316 ± 4.2 kg), seronegative for bovine herpesvirus-1 (BHV-1) and bovine viral diarrhea virus, genotypes 1 and 2 (BVDV-1 and BVDV-2), were sourced from 2 locations. All calves, except 15 non-vaccinated (sentinel) calves, received a single dose of a multivalent modified live vaccine (Titanium 5; AgriLabs, St. Joseph, MO) containing BHV-1, BVDV-1, BVDV-2, bovine parainfluenza virus type 3, and bovine respiratory syncytial virus. Among the vaccinated calves, 2 treatments were concurrently and randomly applied on the basis of initial serum Se status and BW, including 1) injectable trace mineral supplement (ITM; n = 42; 7 mL subcutaneous.; MultiMin, Fort Collins, CO) containing 15, 40, 10, and 5 mg/mL of Cu, Zn, Mn (all as disodium EDTA salts), and Se (as Na selenite) or 2) saline-injected control (Control; n = 42). As a measure of humoral immunity, neutralizing antibody titers were measured on d 0, 14, 30, 60, and 90, relative to vaccine administration. All calves were seronegative for each of the 3 viruses on d 0, and sentinel calves remained seronegative throughout the study. Serum mineral concentrations were evaluated on d 0 and 14. No differences (P ≥ 0.30) in serum Cu, Zn, Mn, or Se were observed between treatments on d 0. Control steers experienced a decrease (P < 0.001) in serum Zn and Se, and ITM steers had an increase (P = 0.007) in serum Cu on d 14 relative to initial d 0 values. On d 14, serum Zn and Se concentrations were greater (P < 0.01) in ITM compared with Control steers. Vaccinated calves experienced marked increases in neutralizing antibody titers by d 30 following vaccine administration. Calves receiving ITM at the time of vaccination experienced greater (P ≤ 0.003) neutralizing antibody titers to BHV-1 on d 14, 30, and 60 compared with Control. These results demonstrate that the injectable trace mineral formulation evaluated in this study, administered concurrently to viral vaccination, does not impair humoral immune responses in beef calves. Further, concurrent administration of ITM and BHV-1 vaccine may enhance the production of neutralizing antibodies to BHV-1 in previously naïve beef calves.

Evaluation of FeOOH performance on selenium reduction

Selenium is an important micronutrient for human and animal health; however, at elevated concentrations, it becomes toxic and could cause serious health problems. The objective of this research is to characterize a commercial adsorbent, FeOOH, and investigate the adsorption kinetics and capacity of Se(IV) onto FeOOH. Nitrogen adsorption–desorption analyses indicate that the Brunauer–Emmett–Teller (BET) specific surface of FeOOH is 361.4 m 2/g. Analyses of spent FeOOH using scanning electron microscope (SEM) and energy dispersion spectrometer (EDS) show that the selenite can be adsorbed onto the FeOOH surface uniformly. The effects of different experimental parameters on the selenite removal efficiency of FeOOH, including solution pH, adsorption time, initial Se concentration and the presence of coexisting contaminants, were also evaluated. The adsorption of selenite was significantly affected by pH, and high removal efficiency was achieved at pH 5.0. SiO 3 2 - and PO 4 3 - both slightly reduced Se(IV) removal, especially at high concentrations, while the presence of V(V) enhanced the adsorption of Se(IV). The pseudo-second-order model demonstrated the best fitting of kinetic data for Se. Adsorption isotherms at various temperatures were developed, and the data fitted the Langmuir model. The thermodynamic characteristics of the sorption process were also evaluated experimentally, and the derived negative Δ G 0 and positive Δ H 0 values indicate that sorption is spontaneous and endothermic.

Validity of administrative data for the diagnosis of primary sclerosing cholangitis: a population-based study

Administrative databases could be useful in studying the epidemiology of primary sclerosing cholangitis (PSC); however, there is no information regarding the validity of the diagnostic code in administrative databases. The aims of this study were to determine the validity of administrative data for a diagnosis of PSC and generate algorithms for the identification of PSC patients. The sensitivity (Se) and positive predictive value (PPV) of a PSC diagnosis based on administrative data from 2000 to 2003 were determined through chart review data. Algorithms were developed by considering variables associated with PSC and coding details. A logistic regression model was constructed using covariates associated with PSC. Based on this model, each subject was assigned a probability of having PSC. A cutoff value was selected that maximized the Se and specificity (Sp) of correctly predicting PSC cases. In the administrative data, the initial Se and PPV were 83.7 and 7.2% respectively. The optimal algorithm included one PSC code and one inflammatory bowel disease code and had Se 56% and PPV 59%. Overall, the algorithms yielded inadequate PPV and Se estimates to identify a cohort of true PSC cases. The predictive model was constructed using six covariates. For this model, the area under the receiver operating characteristic curve was 93.5%. A cutoff of 0.0729 was used, which maximized the Se 81.9% and Sp 90.7%; however, the PPV was 41.0%. An algorithm for the identification of true PSC cases from administrative data was not possible. We recommend that PSC receives a distinct ICD code from ascending cholangitis.

Isotope Fractionation of Selenium During Fungal Biomethylation by Alternaria alternata

The natural abundance of stable Se isotopes may reflect sources and formation conditions of methylated Se. We aimed at (1) quantifying the degree of methylation of selenate [Se(VI)] and (hydro)selenite [Se(IV)] by the fungus Alternaria alternata at pH 4 and 7 and (2) determining the effects of these different Se sources and pH values on 82Se/76Se ratios (δ82/76Se) in methylselenides. Alternaria alternata was incubated with Se(VI) and Se(IV) in closed microcosms for 11-15 days and additionally with Se(IV) for 3-5 days at 30 °C. We determined Se concentrations and δ82/76Se values in source Se(VI) and Se(IV), media, fungi, and trapped methylselenides. In Se(VI) incubations, methylselenide volatilization ended before the 11th day, and the amounts of trapped methylselenide were not significantly different among the 11-15 day incubations. In 11-15 days, 2.9-11% of Se(VI) and 21-29% of Se(IV) were methylated, and in 3-5 days, 3-5% of Se(IV) was methylated. The initial δ82/76Se values of Se(VI) and Se(IV) were -0.69±SD 0.07‰, and -0.20±0.05‰, respectively. The δ82/76Se values of methylselenides differed significantly between Se(VI) (-3.97‰ to -3.25‰) and Se(IV) (-1.44‰ to -0.16‰) as sources after 11-15 days of incubation; pH had little influence on δ82/76Se values. Thus, the δ82/76Se values of methylselenide indicate the source species of methylselenides used in this study. The strong isotope fractionation of Se(VI) is probably attributable to the different reduction steps of Se(VI) to Se(-II) which were rate-limiting explaining the low methylation yields, but not to the methylation itself. The shorter incubation of Se(IV) for 3-5 days showed a large Se isotope fractionation of at least -6‰ before the biomethylation reaction reached its end. This initial Se isotope fractionation during methylation of Se(IV) is much larger than previously published.

Evidences of non-reactive mercury–selenium compounds generated from cultures of Pseudomonas fluorescens

This work was designed to determine chemically inert mercury–selenium (Hg–Se) compounds formed in a culture of Pseudomonas fluorescens exposed to Hg 2+ and Se IV (selenite). To isolate these compounds, different digestion methods were studied and sodium dodecyl sulfate (SDS) lysis was selected. The Hg 0 and non-reactive Hg were determined in two series of cultures containing 0.0–6.00 μg L −1 Se IV (0.0–76.0 μmol L −1) in combination with low 5.00 μg L −1 (0.025 μmol L −1) or high 100 μg L −1 (0.500 μmol L −1) Hg 2+. It was found that Hg 0 formed in the culture decreased with the increase of initial Se IV, while the non-reactive Hg increased with the Se IV. In cultures with low initial [Hg 2+], a median Se IV (2.0 μg L −1 or 25.3 μmol L −1) resulted in about 70% of the added Hg 2+ sequestered as non-reactive Hg, and in culture with high initial Hg 2+, about 40% was sequestered. P. fluorescens was proved to be indispensible for the formation of the non-reactive Hg–Se compounds. The Hg:Se molar ratio in the non-reactive Hg–Se compounds was close to 1, suggesting the existence of mercuric selenide in cells. Mechanisms for the formation of the non-reactive Hg–Se compounds are proposed.

Efficacy of feeding selenium-enriched yeast to finishing beef cattle

<h2>ABSTRACT</h2> An experiment was conducted to evaluate supplementation with Se yeast of a finishing diet containing adequate Se from feedstuffs. Forty calves (307 ± 3.2 kg) were blocked by sex and randomly allotted to 8 pens. After completing acclimation to the diet, pens were randomly assigned within sex to the basal finishing diet (CON) or the basal finishing diet plus 0.34 mg of supplemental Se per kilogram of dietary DM from Se yeast (SUP) for a 130-d finishing period. Body weight and blood samples were obtained at 28-d intervals and before shipping. At slaughter, hot carcass weights were recorded and liver samples collected. After a 48-h chill, standard carcass data and LM samples were obtained. No differences (P > 0.10) in BW, ADG, DMI, feed efficiency, or any carcass measures were detected. Serum Se had a treatment-bytime interaction (P < 0.01) where initial serum Se concentrations were similar, but subsequently SUP calves had greater (P < 0.01) serum Se concentrations than did CON calves. Muscle and liver Se concentrations were lower (P < 0.01) for CON than for SUP calves. There was a treatment-by-sex interaction (P < 0.01), with heifers on SUP having higher liver Se concentrations than those of SUP steers. Results of this experiment indicate that supplementing 0.34 mg/kg Se (DM) from Se yeast to a basal feedlot diet with adequate Se does not increase performance but does result in increased tissue Se concentrations that do not exceed a range determined as normal.

Iron Oxide-Coated GAC Adsorbents: Diffusion-Controlled Sorption of Selenite

Iron oxide-impregnated granular activated carbon has been proven to be successful in removal of selenite (Se(IV)) from aqueous solution. However, the key application component of the mass transfer operations and diffusion coefficient has not been determined. In this study, a modified finite bath diffusion control model with changing initial Se(IV) concentrations was analytically derived, and a constant related to radius of the absorbent particle and the fractional attainment of adsorption was introduced into this model. Batch adsorption studies of Se(IV) onto Fe−GAC were conducted at three different initial concentrations ranged from 0.5 to 2.0 mg/L with loading rate from 0.21 to 0.80 g/L. Results confirmed that the modified model is applicable to both low initial concentration with low fractional attainment and high initial concentration with X̅ > 0.5, while the original model was only applicable for the low initial Se(IV) concentration. The observed sorption kinetics was consistent with the finite bath diffusion, with an average value of 2.9 × 10−4 cm2/s for the product of the distribution coefficient and the effective diffusivity in the adsorption of Se(IV) on the iron oxide-coated granular activated carbon.

Palaeocene–early Eocene inversion of the Phuquoc–Kampot Som Basin: SE Asian deformation associated with the suturing of Luconia

Abstract: The little explored Cambodian and Vietnamese Phuquoc–Kampot Som Basin is a Late Jurassic to Early Cretaceous foreland basin developed in response to the build-up of a palaeo-Pacific magmatic arc. A combination of seismic data, well data and outcrop geology complemented by fission track and U/Pb analysis is used to unravel the basin history. This reveals a hitherto unknown earliest Palaeogene basin inversion associated with the Luconian suturing to SE Asia and the shutdown of palaeo-Pacific subduction underneath SE Asia. The Phuquoc–Kampot Som Basin and the Khorat Basin in Thailand constitute the erosional remnants of a larger basin that covered large parts of SE Asia in Late Mesozoic time, and subsequently became segregated during earliest Palaeogene inversion and erosion. Inversion was focused along the several hundred kilometres long Kampot and Khmer–Chanthaburi fold belts that confine the Phuquoc–Kampot Som Basin and merge with the Mae Ping and the Three Pagodas fault zones. These connections, together with local NW–SE-trending sinistral transpressional faults offshore, indicate a link between initial SE Asian left-lateral strike-slip faulting and the Luconian suturing. The separation between the once unbroken Khmer–Chanthaburi Fold Belt and the Phetchabun Fold Belt in Thailand suggests a 50–100 km Cenozoic left-lateral offset across the Mae Ping Fault Zone.