MOCVD of group III chalcogenides

A review is presented of recent advances in the metal organic chemical vapour deposition (MOCVD) of thin films of group III chalcogenides, including their application for the passivation of GaAs surfaces. The majority of studies involve the deposition of thermodynamic phases of composition ME and M₂E₃ (M?Ga, In; E?S, Se, Te), however, MOCVD allows for the growth of either high-pressure (tetragonal InS) or non-thermodynamic phases (metastable cubic phases of GaS and InSe). Based on the results to date, a series of goals for molecular control over the structure of deposited films is discussed.     

Polymerization of hexachlorocyclotriphosphazene by sulphur and selenium

The thermal bulk polymerization of hexachlorocyclotriphosphazine is described. The possibility of obtaining soluble polymer using sulphur and selenium as catalysts was investigated. It was found that the catalytic activity of selenium was much lower than that of sulphur. Monomeric sulphur may be acting as a chlorine-attractive agent for hexachlorocyclotriphosphazine.     

Influence of arsenic overpressure on Light-Output and degradation behavior of GaAsP: Se Led’s

GaAsP: Se LED’s exhibit low quantum efficiencies if diffused under high arsenic overpressure. A high arsenic pressure during the diffusion process on the other hand results in small rates of initial degradation. If GaAsP: Se LED’s are annealed at 600° C under arsenic overpressure their light-output decreases substantially depending on the selenium doping concentration. A similiar dependence on the selenium doping concentration was observed for the process of light-output degradation in GaAsP: Se LED’s. It is proposed that gallium-vacancy selenium complexes are responsible for the observed phenomena.     

Distribution of some essential trace elements in commercial flour-mill streams

The iron, copper, zinc, manganese, chromium, nickel, selenium, protein and ash contents of two different bread grists and flour samples from the first to fourth break and A to J reduction systems of a commercial flour mill were determined. Iron, zinc, manganese and selenium levels followed the trend of ash and protein with the lowest from the A, B and C rolls and highest from either the fourth break or J roll. Copper and chromium levels were relatively homogeneous among the grist and mill streams while for nickel there was only a slight increase through the break and reduction systems.     

Highly reactive,flexible yet green Se precursor for metal selenide nanocrystals： Se-octadecene suspension （Se-SUS）

A suspension of fine selenium （Se） powder （100 or 200 mesh） in octadecene （Se-SUS） has proven to be a high-performance, versatile, convenient, reproducible, yet green Se precursor. The advantages of Se-SUS arise from its highly reactive chemical nature and flexibility. These two features made it possible to carry out the synthesis of high quality metal selenide nanocrystals with diverse compositions and structures, including binary, core/shelL transition metal doped, and complex composition nanocrystals. These successes further demonstrated that Se-SUS is a powerful Se precursor for solving a few long- standing challenges in the synthesis of high quality selenide nanocrystals. For instance, Se-SUS was successfully employed as a Se precursor for shell growth in high quality core/shell nanocrystals to replace expensive and highly toxic precursors, such as Se-phosphine and bis-trimethylsilyl selenide, with greatly lowered epitaxial temperatures （as low as 150℃） to avoid alloying. As another example, Se-SUS enabled ＂co-nucleation doping＂ as a means of preparing high quality Mn doped ZnSe nanocrystals with pure, stable, and highly efficient dopant fluorescence.     

Selenium bioaccumulation in eutrophic lake – Dąbie Małe Lake,Poland

While the world literature presents many studies on the occurrence of selenium in aquatic ecosystems, the risks associated with overexposure of hydrobionts to this element and the consequences of its magnification in the food chain (areas rich in Se), there are few studies on Se concentration in Poland's water bodies and watercourses (Se deficient area). The objective of the study was to assess the Se bioaccumulation in D?bie Ma?e Lake, based on Se concentration in the water, bottom sediments, and organs of Rutilus rutilus and Perca fluviatilis. The accumulation and biomagnification factor averaged 231 ± 69 and 1.2, respectively. Bioconcentration factor, calculated as Se in muscle divided by Se in water, ranged 35–104. Although Se concentrations in bottom sediments and fish were generally lower than the values reported in the literature, Se concentration in the water exceeded 2 µg/L, recommended value as a probable safe water concentration for wildlife.     

Study on selenium extraction from anode slime

Taking a copper anode slime as the raw material, a novel process for selenium extraction was studied. The primary selenium recovery can reach above 88.5 , and the quality index of selenium product can be up to 99.5 ,. The economic benefit resulted is remarkable and environment has been protected.     

三重四极杆ICP-MS测定烟叶中的痕量硒

为准确测定烟叶中的痕量硒，本研究使用三重四极杆ICP-MS进行测定，并与单四极杆ICP-MS进行比较。试验表明，三重四极杆ICP-MS采用两级质谱进行质量筛选，选择O₂作为反应气体，将待测元素Se质量数转移到无干扰的质量数区域，能消除多原子离子和双电荷离子的干扰，可获得更加准确的结果。⁷⁸Se、⁸⁰Se和⁸²Se三种同位素的回收率分别为99.1%、98.3%、99.2%，相对偏差（RSD）分别为1.59%、2.07%、1.32%，线性相关系数r>0.9999。结果还表明，三重四极杆ICP-MS方法测定烟叶中的痕量硒受干扰因素小，可获得更准确结果。