Study on removing selenate from groundwater by autohydrogenotrophic microorganisms

Performance of autohydrogenotrophic bac- teria for bio-reduction of selenate （Se（VI）） under anaerobic conditions was investigated with batch experiments. Results showed Se（VI） was bio-reduced to selenite （Se（IV）） as an intermediate product, and then to elemental selenium （Se）. Reduction kinetics could be described by the pseudo-first-order model. In particular, the influences of pH value and temperature on Se（VI） reduction by autohydrogentrophic organisms were examined. The high degradation rate was achieved at pH 7.0 to 8.0; and the best reduction temperature was between 25℃ and 35℃. This study is of help for treating groundwater with selenium contamination by autohydrogenotrophic bacteria as well as its reactor development.

Biological removal of selenate in saline wastewater by activated sludge under alternating anoxic/oxic conditions

Selenium (Se)-containing industrial wastewater is often coupled with notable salinity. However, limited studies have examined biological treatment of Se-containing wastewater under high salinity conditions. In this study, a sequencing batch reactor (SBR) inoculated with activated sludge was applied to treat selenate in synthetic saline wastewater (3% w/v NaCl) supplemented with lactate as the carbon source. Start-up of the SBR was performed with addition of 1–5 mM of selenate under oxygen-limiting conditions, which succeeded in removing more than 99% of the soluble Se. Then, the treatment of 1 mM Se with cycle duration of 3 days was carried out under alternating anoxic/oxic conditions by adding aeration period after oxygen-limiting period. Although the SBR maintained soluble Se removal of above 97%, considerable amount of solid Se remained in the effluent as suspended solids and total Se removal fluctuated between about 40 and 80%. Surprisingly, the mass balance calculation found a considerable decrease of Se accumulated in the SBR when the aeration period was prolonged to 7 h, indicating very efficient Se biovolatilization. Furthermore, microbial community analysis suggested that various Se-reducing bacteria coordinately contributed to the removal of Se in the SBR and main contributors varied depending on the operational conditions. This study will offer implications for practical biological treatment of selenium in saline wastewater.

Chromate and selenate hydrocalumite solid solutions and their applications in waste treatment

Hydrocalumite, a calcium aluminate hydrate phase, consists of positively-charged structure units, and is therefore an ideal candidate for accommodating anionic contaminants. In this study, a series of batch experiments was carried out to examine the uptake of chromate and selenate by hydrocalumite. To determine the uptake capacity and long-term stability, hydrocalumite solid solutions between chromate/selenate and hydroxyl were synthesized over a reaction time of more than one year. At a ratio of water to initial solids added (CaAl2O4+CaO) of 75: 1, the maximum uptake capacities were over 77 and 114 g/kg for Cr and Se, respectively.These values are very close to the theoretical uptake capacities of chromate and selenate hydrocalumite end-members (81 and 118 g/kg, respectively). The oxyanion removal efficiency from solution was above 95%. Due to the high uptake capacity and anion removal efficiency of hydrocalumites, their application in wastewater treatment is promising. Hydrocalumites are also important hydration products of cementitious materials and the long-term stability of these phases is of significance for application in solidification/stabilization technology.

月陆地区次级撞击坑特征及年龄统计方法

通过撞击坑的大小频率计算月表的地质年龄是一种行之有效的方法,包括累积分布法和相对分布法。其中累计分布法在已知撞击坑直径范围的基础上,可分为3种年代函数计算月表的地层单元,分别是Melosh和Vickery 1989(直径大于4km撞击坑),Neukum 1983(直径大于1km撞击坑)和李坤等2012(直径小于1km撞击坑)。应用高分辨率影像SELENE TC(10m/pixel)数据,完成了Apollo 14及Apollo 16登月区域地层单元的解译,并应用撞击坑直径-频率统计方法获取同一地层单元的形成年龄。通过与Apollo登月区域样品同位素年龄对照,得出Neukum 1983(直径大于1km撞击坑)相对于其他几种方法更加准确,同时分析了撞击坑的退化、次级撞击坑影响等相关问题。

乌鲁木齐天文站在月球探测同波束干涉测量中的作用

首先简要介绍同波束干涉测量技术,随后叙述中国科学院国家天文台乌鲁木齐天文站在2008年成功完成了约200 h日本月球卫星SELENE同波束较差甚长基线干涉测量,并阐述乌站在此次VLBI中的作用。给出利用SELENE的观测数据,分析、解算出乌站25 m天线与日本VERA网相关台站基线Rstar、Vstar的S1、S2、S3、X频段的较差相关相位、较差相关相位残差,以及对各频段的较差相关相位、较差相关相位残差比对,最后获得较差相位时延。结果显示,同波束甚长基线干涉测量比传统VLBI观测得到的群时延精度提高了1～2个量级。

GEODYN-Ⅱ软件移植和40阶次月球重力场的解算

将GEODYN-Ⅱ软件从工作站移植到了PC机平台上,其计算效率明显高于工作站平台上5~10倍。利用移植版本的GEODYN-Ⅱ软件和SELENE卫星轨道数据求解了40阶次月球重力场模型,以及月球自由空气重力异常场和月表重力异常场。其自由空气重力异常场与SELENE小组在SCIENCE上的结果是一致的。同时与LP165Q对比,在月球背面其解算的40阶次月球重力场的精度比LP165Q模型要高,但是相对于月球正面仍没有LP165P的精度高,还有待进一步改进。

A dual role of selenium in the growth control of seedlings of Stylosanthes humilis

The growth of seedlings of Townsville sytlo (Stylosanthes humilis H.B.K.) is inhibited by aluminium (Al) ions, their elongation being re-covered with sodium selenate at 1.0 μM. Methyl viologen and hydrogen peroxide, reactive oxy-gen species (ROS)-generating compounds, also inhibited seedling elongation and again growth was relieved by selenate. Selenate, thus, seemed to be operating as a ROS quencher, since N-acetylcysteine (NAC), an antioxidant com-pound, also stimulated largely the growth of Al-inhibited seedlings. At a higher concentra-tion (0.1 mM), however, selenate inhibited seed-ling growth and elongation was recovered by NAC. Ethylene production by selenate plus NAC-treated seedlings was very higher and thus the gaseous hormone was not responsible for the seedling growth inhibition caused by sele-nate. Hence, it seems that at high levels sele-nate operates as a ROS-generating compound whose effects were counteracted by NAC. It can be deduced that, at low concentration, sele-nates behave as a ROS quencher and at high level as a ROS-promoting species.

新53阶次月球重力场及其精细结构

月球重力场是了解月球内部结构的重要信息之一.日本SELENE卫星首次获得月球背面卫星轨道的直接探测数据并建立了更高精度的全月球重力场模型.本文根据日本公布的采样间隔为60s、轨道高度为100km的SELENE卫星观测资料并利用作者移植的GEODYN-II微机版本软件求解出新53阶次月球球谐场模型LG-53.经过测试表明移植后的微机版本比原始工作站版本的计算效率提高了5到10倍.理论上表明60s采样间隔、100km高度的轨道数据能够计算出60阶次的月球球谐系数模型,但是作者在实际计算过程中发现:在接近理论阶次(60阶次)的一系列模型中出现了平行于经线的高频噪声,且模型越接近理论阶次其噪声越高.因此本文将53阶次月球球谐系数模型LG-53作为最后的解算结果并建立各种月球重力异常场,并将其与美国GLGM-2(70阶次)模型和利用嫦娥1号数据解算出的CEGM-01(50阶次)模型对比,发现新53阶次重力场模型LG-53在高纬度和月球背面都显示出了更高分辨率的异常特征;与美国LP165P(165阶次)模型对比发现LG-53所建立的自由空气重力异常在月球背面不存在LP165P中所出现的高频噪声.与日本90阶次SGM90d模型对比后发现新模型的精度较日本模型还有所差距.主要是由于两者参与计算的数据采样率不同所致.53阶次的模型LG-53能够反映100km尺度的重力异常,而日本90阶次模型则可以反映60km尺度的异常.利用新53阶次模型计算的自由空气重力异常图并结合月球地形图探讨了四种类型的Mascon重力异常特征及其地形特征.

Inhibitory effect of IFN on CFU-GM antagonized by some hemopoietic stimulators

The PE of murine CFU-GM effected by three types of CSF,HCS,Li2CO3 and Na2SeO4,all of which used to be able tO reverse the inhibitory effectof IFN on CFU-GM,were reported in this paper.The results were as follows:The three types of CSF could antagonize partially the inhibitory effect of IFN onCFU-GM,trace Na2SeO4 and Li2CO3 could stimulate the proliferation ofCFU-GM,and increase more than 200% of the PE inhibited by IFN,trace HCSalso could reverse partially the inhibition of IFN on CFU-GM.

Recent Developments to Mitigate Selenium Deficiency in Agricultural Eco-Systems

Under changing climate,trace elements like selenium(Se)have emerged as vital constituent of agro-ecosystems enabling crop plants to off-set the adverse effects of suboptimal growth conditions.The available form of selenium is important for boosting its bioavailability to crop plants having varied agro-botanical traits and root architectural systems.As compared to selenite,the selenate has a weaker soil bonding,higher absorption in the soil solution which results in a comparatively absorption by plant roots.Various factors including dry climate,high pH,optimal ambient air temperature,less accumulation of water,and low concentration of organic matter in the soil tend to boost the selenate ratio in the soil.The use of selenium pelleted seeds has emerged as an interesting and viable alternative to alleviate selenium deficiency in agricultural eco-systems.Similarly,the co-inoculation of a mixture of Selenobacteria and Arbuscular mycorrhizal fungi represents an evolving promising strategy for the bio-fortification of wheat plants to produce selenium-rich flour to supplement human dietary needs.Furthermore,in-depth research is required to assure the effectiveness of biological fertilization procedures in field conditions as well as to explore and increase our understanding pertaining to the underlying main mechanisms and channels of selenium absorption in plants.The focus of this review is to synthesize the recent developments on Se dynamics in soil-plant systems and emerging promising strategies to optimize its levels for crop plants.Recent developments regarding the use of micro-organisms as a biotechnological mean to enhance plant nutrition and crop quality have been objectively elaborated.The study becomes even more pertinent for arid and semi-arid agro-ecosystems owing to the potential role of selenium in providing stress tolerance to crop plants.Moreover,this review synthesizes and summarizes the recent developments on climate change and bioavailability,and the protective role of selenium in crop plants.

Influence of Selenium on Growth, Antioxidants Production and Physiological Parameters of Rice (<i>Oryza sativa</i>L.) Seedlings and Its Possible Reversal by Coapplication of Sulphate

The effect of selenate (Na2SeO4) and sulphate (Na2SO4) was studied on growth and metabolism in two rice cultivars cv. satabdi and cv. khitish. Selenate at low concentration (2 μM) expressed growth promoting effect on rice seedlings as opposed to its high concentration (≥20 μM) where the test seedlings showed stunted growth with browning at the apices of both roots and shoots. The chlorophyll contents showed a dose dependent effect. Both chlorophyll a and chlorophyll b contents were inhibited with increase in selenate concentrations. The effect was more pronounced in cv. satabdi compared to cv. khitish.The level of accessory pigments was deferentially affected by selenium treatment. Simultaneously, the fluorescence intensity and Hill activity decreased with increase in selenate concentrations in the test seedlings. It is assumed that selenium plays a protective role in plants subjected to stress and prevents the formation of reactive oxygen species (ROS) in the cells. Higher selenate concentrations (≥20 μM) exerted variable effect on the activities of enzymatic antioxidants viz.;superoxide dismutase (SOD), catechol peroxidase (CPX) and catalase (CAT) in the test seedlings. The activity of SOD increased with increase in selenate concentrations, whereas activities of CAT and CPX decreased. Under high selenate concentrations, the levels of oxidative stress markers, viz.;proline, H2O2 and MDA were also enhanced. Selenium induced accumulation of total soluble sugar and increased the level of both reducing and non reducing sugars in both the test cultivars. The starch contents concomitantly decreased with rise in selenate concentrations. Moreover, the nutrient contents of test seedlings were significantly influenced by selenium. The Na and K levels gradually increased whereas Ca, Mg and Fe levels decreased on application of selenate. Joint application of 10 mM sulphate and selenate showed significant alterations on all parameters tested with respect to selenate treatment alone. Partial to complete amelioration occurred in the test seedlings treated with high concentrations of selenate and sulphate. Our study shows that selenium at low concentration had a stimulatory effect on growth and metabolism as against high concentrations which proved to be toxic to the rice seedlings obtained from both the cultivars. Effects were more pronounced in cv. satabdi than in cv. khitish which is considered to be comparatively tolerant to selenium. The dose dependent influence of selenium on the physiological and biochemical responses of test seedlings may be reversed by co-application with sulphate.

Selenium Modulates Growth and Thiol Metabolism in Wheat (<i>Triticum aestivum</i>L.) during Arsenic Stress

Arsenic affects plants by disrupting their growth and metabolism while selenium, an essential micronutrient has beneficial role in stress tolerance. Owing to the antioxidative capacity of selenium, it can counteract detrimental effects of arsenic induced stress in plants. The interactive influence of arsenate and selenate on the growth, arsenic and selenium accumulation, activities of non-enzymatic and enzymatic antioxidants, levels of ascorbate, α-tocopherol, total glutathione and activities of glutathione regulatory enzymes along with characterization and quantification of phytochelatins in growing wheat (Triticum aestivum L.) seedlings were investigated. Rate of arsenic accumulation was increased in arsenate treated seedlings while in seedlings treated jointly with arsenate and selenate, arsenic accumulation decreased. Arsenate stress resulted decrease in ascorbate and total glutathione contents, activities of the glutathione metabolism enzymes while significantly increased the levels of α-tocopherol and phytochelatins (PC2 and PC4), along with activities of ascorbate peroxidase and ascorbic acid oxidase in the test seedlings. The effects were more pronounced in roots than in shoots. Joint application of arsenate along with selenate was able to overcome the adverse effects caused by arsenic alone to variable extents by exhibiting significant alterations of all parameters tested, imparting better growth and thiol metabolism in the test seedlings. Our results conclude that application of selenium fertilizer in arsenic contaminated soil might be favourable to improve growth and defense ability in wheat against arsenic toxicity.

A New Reagent for the Reduction of N-Arylsulfonylimines

N-arylsulfonyimines were reduced easily to the corresponding N-arylsulfonylalnineswith potassium selenated borohydride (KBH2Se3) under reflux in formamide.

基于同波束VLBI的双差分电离层电子总量抖动与角距离关系模型

深空探测器信号穿过地球电离层时会产生信号时延和相位抖动,从而对VLBI(Very Long Baseline Interferometry)测量精度产生很大影响.利用日本SELENE 2颗小卫星Rstar和Vstar的4测站6基线长达1 yr的同波束VLBI观测数据,首次解算出了双差分电离层电子总量抖动的均方根和角距离的关系模型.6条基线的双差分电离层电子总量抖动的均方根r(单位为TECU)和角距离θ(?)的关系模型为:r=0.773θ+0.562,由基线反演出的4个测站的关系模型为:r=0.554θ+0.399.研究成果对差分相时延的解算和行星电离层掩星观测研究均有重要参考意义.

Preliminary Study on the Standard of Selenium Content in Agricultural Products

With the improvement of living standards, people pay more attention to the agricultural products with health protection function, and the selenium-rich agricultural products attract more and more consumers. The main biological role of selenium is to resist oxidation and inflammatory response, mainly focusing on resisting aging, preventing cardiovascular disease, protecting eyesight, counteracting or destroying the toxic properties, preventing cancer and thyroid disease. In most areas of China, there is a widespread shortage of selenium, thus producing selenium-rich agricultural products to provide natural selenium-rich health food to the areas in need of selenium, has gradually become a new hot spot of China's health food industry, but high content of selenium in food is detrimental to human body, even leads to selenium intoxication, and artificially adding inorganic selenium is difficult to guarantee that the selenium content of agricultural products is not exceeded. According to human body's daily demand for selenium in dietetics and the content of selenium in agricultural products in the Chinese food composition table, we put forward the recommendations on the standard of selenium in agricultural products, in order to provide the basis for China to formulate the health standard of selenium content in selenium-rich agricultural products.

Preparation of CuInSe_2 films by ultrasonic electrodeposition-selenization and the improvement of their surface morphology

The CulnSe2 compound was prepared by selenization of Cu-In precursor, which was ultrasonic electrodeposited at constant current. CulnSe2 films were compacted to improve surface morphology. The films were characterized by X-ray diffractometry （XRD）, scanning electron microscopy （SEM）, and energy dispersive spectroscopy （EDS）. It is indicated that ideal stoichiometrie CulnSe2 films can be obtained by the selenization of Cu-In precursor deposited at a current density of 20 mA/cm^2. Single-phase CulnSe2 is formed in the selenization proeess, and it exhibits preferred orientation along the （112） plane. The CulnSe2 films with smooth surface can be obtained under the pressure of 500 MPa at 60℃.

Obtaining the thin Semiconductive Covering Re-Se From Sulphate Electrolyte

There have been investigated the kinetics and mechanism of the cathode electrodeposition of thin coverings Re-Se?from the sulphate electrolyte, containing NH4ReO4, SeO2 and H2SO4. On the base of X-ray phase analysis and by the method of cyclic avometry there have been determined the content of obtained coverings, electrosettled at the various concentrations of components in electrolyte. The co-deposition process was shown to be attended by depolarization, which is due to the energy release upon the formation of the alloy.

“月女神”探测器揭开日本月球探测的新篇章

1 概述 2007年9月14日，日本“月女神”（SELENE）探测器由H-2A火箭从种子岛航天发射中心发射升空。SELENE探测器计划是日本为未来载人登月迈出的第一步。

Two-step growth of VSe_2 films and their photoelectric properties

We put forward a two-step route to synthesize vanadium diselenide(VSe_2), a typical transition metal dichalcogenide(TMD). To obtain the VSe_2 film, we first prepare a vanadium film by electron beam evaporation and we then perform selenization in a vacuum chamber. This method has the advantages of low temperature, is less time-consuming, has a large area, and has a stable performance. At 400?C selenization temperature, we successfully prepare VSe_2 films on both glass and Mo substrates. The prepared VSe_2 has the characteristic of preferential growth along the c-axis, with low transmittance.It is found that the contact between Al and VSe_2/Mo is ohmic contact. Compared to Mo substrate, lower square resistance and higher carrier concentration of the VSe_2/Mo sample reveal that the VSe_2 film may be a potential material for thin film solar cells or other semiconductor devices. The new synthetic strategy that is developed here paves a sustainable way to the application of VSe_2 in photovoltaic devices.

Effects of silver-doping on properties of Cu(In,Ga)Se_(2) films prepared by Cu In Ga precursors

The AgCuInGa alloy precursors with different Ag concentrations are fabricated by sputtering an Ag target and a CuInGa target.The precursors are selenized in the H_(2)Se-containing atmosphere to prepare(Ag,Cu)(In,Ga)Se_(2)(ACIGS)absorbers.The beneficial effects of Ag doping are demonstrated and their mechanism is explained.It is found that Ag doping significantly improves the films crystallinity.This is believed to be due to the lower melting point of chalcopyrite phase obtained by the Ag doping.This leads to a higher migration ability of the atoms that in turn promotes grain boundary migration and improves the film crystallinity.The Ga enrichment at the interface between the absorber and the back electrode is also alleviated during the selenization annealing.It is found that Ag doping within a specific range can passivate the band tail and improve the quality of the films.Therefore,carrier recombination is reduced and carrier transport is improved.The negative effects of excessive Ag are also demonstrated and their origin is revealed.Because the atomic size of Ag is different from that of Cu,for the Ag/(Ag+Cu)ratio(AAC)≥0.030,lattice distortion is aggravated,and significant micro-strain appears.The atomic radius of Ag is close to those of In and Ga,so that the continued increase in AAC will give rise to the Ag;or Ag;defects.Both the structural and compositional defects degrade the quality of the absorbers and the device performance.An excellent absorber can be obtained at AAC of 0.015.