纳米硒的制备与应用研究进展

硒是生物体必需的微量元素之一,具有重要的生理功能,而纳米硒具有毒性低、生物活性高等特征.综述了载体/模板法、溶胶法、固相法等纳米硒的制备与保护方法,并简要介绍了纳米硒在保健食品、医药以及饲料添加剂等领域中的应用.     

Cadmium cathodic deposition on polycrystalline p-selenium: Dark and photoelectrochemical processes

Cathodic reduction of Cd²⁺ on p-Se proceeds at low overpotential in the dark and results in bulk Cd, while the underpotential deposition is kinetically inhibited. Cadmium adlayer is photoelectrochemically deposited on illuminated electrode 0.7 V above E(Cd²⁺/Cd). The adlayer cathodic deposition under illumination proceeds with simultaneous formation of CdSe nanoparticles. Potentiodynamic electrochemical impedance spectroscopy has discriminated the two products of the photoelectrochemical reaction both by their potentials of anodic oxidation and by characteristic dependences of impedance on potential. Anodic oxidation of CdSe nanoparticles gives a sharp peak of real impedance in low frequencies close to the corresponding anodic current peak in cyclic voltammogram. The impedance peak appears below a threshold frequency f_t. The latter separates two modes of diffusion in anodic dissolution of CdSe nanoparticles. The diffusion proceeds independently at different particles above f_t and turns to cooperative mode below the threshold frequency. Due to this effect, information on spatial distribution of growing nuclei on electrode surface in early stages of electrodeposition can be obtained from potentiodynamic impedance spectra.     

催化光度法测定痕量硒的研究

利用 1 10—邻菲 口罗 啉为活化剂 ,硒 (IV)催化高碘酸钾氧化酸性铬蓝K褪色的指示反应 ,方法具有一定的选择性 ,表现摩尔吸光系数可达 3 6 5× 10 6Lmol-1cm-1。测量的线性范围为 0～ 10 0ng/ 2 5mL ,本法可直接用于头发、茶叶、火腿、牛肉等样品中痕量硒的测定 ,结果令人满意     

靛蓝胭脂红—溴酸钾催化光度法测定茶叶中微量硒

研究了硒（IV）对溴酸钾氧化靛蓝胭脂红褪色反应的催化作用及NaCl的活化作用,建立了一种测定微量硒的方法,硒量在0－1．0ug/mL范围内与△A呈线性关系,检出限为0．02ug/mL,在NaF及尿素存在下,多数常见离子无干扰,本法灵敏度及选择性较高,用于茶叶中微量硒的测定,结果满意。     

Bridgman-grown CuInSe2 + x with Na or Na2Se

Elemental sodium Na⁰ was introduced into Bridgman melts with the two compositions CuInSe₂ (stoichiometric) and CuInSe_2.2 (excess Se) in amounts of 0, 0.1, 0.5, 1, 2 and 3 at.%. In the resulting Bridgman-grown ingots brittleness generally increased with increased Na⁰ content, as found earlier also with Na₂Se additions. Measured thermoelectric power (α) changed sign from p- to n-type in stoichiometric ingots above 0.1 at.% Na⁰, while it remained entirely p-type in ingots with excess Se. However, in earlier work with increasing Na₂Se in excess Se ingots, α decreased by about 70%, corresponding to an apparent hole concentration increase of more than an order of magnitude. Four different deposits were observed in the containing ampoules: white and reddish deposits, and grey and black spots. These were found to contain sodium, copper, Cu₃Se₂ and selenium, respectively.     

顺序注射氢化物发生-原子荧光光谱法测定富硒鸡蛋中的硒

本研究建立了一种顺序注射氢化物发生-原子荧光光谱法测定富硒鸡蛋中的Se含量的方法,同时讨论了共存离子的干扰情况。在最佳实验条件下,Se的检出限为0.082μg/L,加标回收率为94.2%～102.9%。     

Heavy coal combustion as the dominant source of particulate pollution in Taiyuan, China, corroborated by high concentrations of arsenic and selenium in PM10

Coal burning generates toxic elements, some of which are characteristic of coal combustion such as arsenic and selenium, besides conventional coal combustion products. Airborne particulate samples with aerodynamic diameter less than 10 microm (PM(10)) were collected in Taiyuan, China, and multi-element analyses were performed by inductively coupled plasma atomic emission spectrometry (ICP-AES) and inductively coupled plasma mass spectrometry (ICP-MS). Concentrations of arsenic and selenium from ambient air in Taiyuan (average 43 and 58 ng m(-3), respectively) were relatively high compared to what is reported elsewhere. Arsenic and selenium were found to be highly correlated (r=0.997), indicating an overwhelmingly dominant source. Correlation between these two chalcophile elements and the lithophile element Al is high (r is 0.75 and 0.72 for As and Se, respectively). This prompted the hypothesis that the particles were from coal combustion. The enrichment of the trace elements could be explained by the volatilization-condensation mechanism during coal combustion process. Even higher correlations of arsenic and selenium with PM(10) (r=0.90 and 0.88) give further support that airborne particulate pollution in Taiyuan is mainly a direct result of heavy coal consumption. This conclusion agrees with the results from our previous study of individual airborne particles in Taiyuan.     

Soil migration, plant uptake and volatilisation of radio-selenium from a contaminated water table

The properties of (79)Se make it of likely potential importance in safety studies for geological disposal of radioactive wastes. Despite a substantial literature on toxic and nutritional aspects of selenium in the environment little consideration has been given to the behaviour of radioactive selenium and its potential transfer from a radioactive waste repository to the biosphere. Column experiments (15 x 50 cm), using a sandy loam soil, indicated that the upwards migration of (75)Se (as a surrogate for (79)Se) from a contaminated water table was dependent upon the redox status of the soil. Low redox conditions within the water table strongly limited upwards (75)Se soil migration, presumably due to the immobilisation of reduced Se species. Under natural conditions, (79)Se from a radioactive waste repository is therefore likely to accumulate at considerable depth. As a consequence, its absence from the rooting zone is likely to limit its transfer into plants. Nevertheless, the column experiments indicated that when an overlap between roots and soil contamination occurs, uptake into the plant is observed. Quantification of (75)Se volatilisation from the column surfaces suggested that this is a significant pathway by which (79)Se may move either directly from soil to the atmosphere, or from soil to plants and then to the atmosphere.     

12°Bx富硒红啤酒的研制

介绍了一种含硒丰富的啤酒——12Bx富硒红啤酒的研制方法,主要是利用富硒红曲米和麦芽,通过糖化、发酵等手段而制成。     

微波消解ICP—AES法测定茶叶中铅、砷、铜、铁、锌、硒等12种元素的含量

研究了用微波消解前处理样品,ICP－AES法同时测定茶叶中铅、砷、铜、镉、锰、铁、锌、硒等12个元素含量的方法,并对样品前处理、酸度及茶叶中共存元素干扰的影响等因素进行了探讨,该方法的回收率在84.5%－115％之间,精密度RSD均小于9％,该方法能满足茶叶测定要求。