Heterostructure CdS/ZnS nanoparticles as a visible light-driven photocatalyst for hydrogen generation from water

(CdS)_x/(ZnS)_1–x nanoparticles were synthesized as a visible light-driven photocatalyst using the stepped microemulsion technique with a series of the ratio factors (x). The photocatalytic test results showed that (CdS)_x/(ZnS)_1-x with x = 0.8 had the highest photo-reactivity for H₂ production from water under visible light. The composite (CdS)_0.8/(ZnS)_0.2 catalyst had a heterogeneous structure that exhibited a much greater photocatalytic hydrogen production activity than either pure CdS or the homogeneous Cd_0.8Zn_0.2S solid solution. ZnS deposition also was shown to largely improve the stability of CdS in the heterostructured CdS/ZnS catalyst. Thermal treatment of the catalyst, i.e., annealing (CdS)_0.8/(ZnS)_0.2 at 723 K, improved the crystallinity of the catalyst and increased its photocatalytic H₂ production rate by more than 36 times. Deposition of Ru on the surface of the catalyst particles by in situ photo-deposition further increased the photo-H₂ generation rate by 3 times. The photocatalyst of 0.5%Ru/CdS/ZnS achieved the highest H₂ production activity, at a rate of 12650 μmol/g-h and with a light to hydrogen energy conversion efficiency of 6.5%.     

Comparison of ANN,MVR, and SWR models for computing thermal efficiency of a solar still

In this paper, the viability of modeling the instantaneous thermal efficiency (η_ith) of a solar still was determined using meteorological and operational data with an artificial neural network (ANN), multivariate regression (MVR), and stepwise regression (SWR). This study used meteorological and operational variables to hypothesize the effect of solar still performance. In the ANN model, nine variables were used as input parameters: Julian day, ambient temperature, relative humidity, wind speed, solar radiation, feed water temperature, brine water temperature, total dissolved solids of feed water, and total dissolved solids of brine water. The η_ith was represented by one node in the output layer. The same parameters were used in the MVR and SWR models. The advantages and disadvantages were discussed to provide different points of view for the models. The performance evaluation criteria indicated that the ANN model was better than the MVR and SWR models. The mean coefficient of determination for the ANN model was about 13% and14% more accurate than those of the MVR and SWR models, respectively. In addition, the mean root mean square error values of 6.534% and 6.589% for the MVR and SWR models, respectively, were almost double that of the mean values for the ANN model. Although both MVR and SWR models provided similar results, those for the MVR were comparatively better. The relative errors of predicted η_ith values for the ANN model were mostly in the vicinity of ±10%. Consequently, the use of the ANN model is preferred, due to its high precision in predicting η_ith compared to the MVR and SWR models. This study should be extremely beneficial to those coping with the design of solar stills.     

绝缘子表面RTV憎水性与其放电的紫外成像结果关系研究

室温硫化硅橡胶(RTV)涂料在运行过程中会逐渐老化,可采用憎水性测量和理化手段分析其老化程度,但无法对运行中的绝缘子进行评估。通过涂污的方式模拟绝缘子表面RTV憎水性的减弱,对绝缘子串加压并用紫外成像仪记录放电过程,研究憎水性与紫外成像结果的关系。分析放电产生的紫外光子数和光斑面积发现,绝缘子串表面RTV憎水性越差,其发生显著放电的电压越低,相同电压下放电程度越剧烈。研究成果为运行中绝缘子RTV憎水性能的评估提供了一种新思路。     

麻疯树核糖体失活蛋白(curcin)的化学修饰与其活性的关系

通过无细胞体系蛋白合成抑制活性的测定,结合荧光光谱和圆二色谱技术,对麻疯树核糖体失活蛋白(cur-c in)部分氨基酸残基进行特异性化学修饰,探讨维持curc in活性的必需氨基酸基团及修饰对curc in结构的影响.结果表明,组氨酸和半胱氨酸的修饰对活性没有影响.色氨酸和赖氨酸的修饰使curc in的活性分别下降了50%和100%,表明色氨酸和赖氨酸是维持curc in活性的重要残基.精氨酸修饰导致curc in的抑制活性完全丧失,内源荧光强度下降,最大发射波长发生红移,CD谱发生显著变化;表明精氨酸也是维持curc in活性的必需残基,并且对空间结构影响较大,推测对精氨酸的修饰破坏了精氨酸与其它基团的连接,导致curc in分子结构发生改变,失去和底物结合的能力,因而活性丧失.图3表1参34     

Age-dependent association between testosterone and crown UV coloration in male blue tits (Parus caeruleus)

The proximate basis of sexual traits can suggest mechanisms maintaining honesty in signalling. A central role hereby has been attributed to testosterone, although its importance for brightly coloured plumage has been questioned. We determined circulating testosterone levels in male blue tits captured at the start of breeding and demonstrated an age-dependent relationship between testosterone and male crown UV/blue coloration. In yearling males, testosterone increases with increasing ornamentation (higher UV chroma, higher chroma, more UV-shifted hue), whereas in older males, this relationship is negative, with less UV-ornamented males having higher testosterone. This pattern is robust since it occurred in 2 years, before and after egg laying, and in males sampled during the day and during the night, despite a tenfold difference in testosterone levels. Since more UV-ornamented young males gain higher within-pair paternity, while less UV-ornamented older males achieve more extra-pair matings, the results imply that higher testosterone is associated with reproductive success and attractiveness in both age classes. We hypothesise that this relationship could result from causal effects of testosterone on coloration or through associations with behaviour and suggest ways to test these hypotheses. Our results caution against premature dismissal of a potential role for testosterone in maintaining honesty of plumage signals.     

Application of recording films of solar radiation for environmental and ecological research

Global solar radiation is recorded by fading of the colored film into which azo-dye is impregnated with use of organic solvent. Oil Red O, Sudan I, Sudan IV and Pyridylazonaphthol are used as the azo dye. These films can be applied to measure the solar radiation in many kinds of environmental or ecological conditions. The merits of the film compared with usual measurements are to be: unnecessary of any electric sources; cheap and mass-productive easily; suitable to integrate solar radiation for long time; easy dealing in out-door or underwater conditions; possible to use on leaves of any plants because of light weight; possible to use in a lot of points at the same time.     

用185nm UV降解水中二苯甲酮和孔雀石绿

研究了185nm紫外光降解水中二苯甲酮和孔雀石绿和总有机碳(TOC)的规律.研究了浓度、体积、流速、pH等因素对二苯甲酮的降解效果的影响.通过改变污染物初始浓度、体积、流量、pH值以及添加无机离子来讨论185nm紫外光对孔雀石绿的降解效果,探讨了降解的最佳条件.降解达到了治理水中二苯甲酮和孔雀石绿污染的目的.用这种方法降解水中二苯甲酮和孔雀石绿,去除率能够达到99.9%以上,是一种非常有效的治理污染方法.实验同时验证了185nm UV降解水中的二苯甲酮和孔雀石绿符合准一级动力学规律.     

Mycobiota and mycotoxins in bee pollen collected from different areas of Slovakia

Contamination by microscopic fungi and mycotoxins in different bee pollen samples, which were stored under three different ways of storing as freezing, drying and UV radiation, was investigated. During spring 2009, 45 samples of bee-collected pollen were gathered from beekeepers who placed their bee colonies on monocultures of sunflower, rape and poppy fields within their flying distance. Bee pollen was collected from bees’ legs by special devices placed at the entrance to hives. Samples were examined for the concentration and identification of microscopic fungi able to grow on Malt and Czapek-Dox agar and mycotoxins content [deoxynivalenol (DON), T-2 toxin (T-2), zearalenone (ZON) and total aflatoxins (AFL), fumonisins (FUM), ochratoxins (OTA)] by direct competitive enzyme-linked immunosorbent assays (ELISA). The total number of microscopic fungi in this study ranged from 2.98 ± 0.02 in frozen sunflower bee pollen to 4.06 ± 0.10 log cfu.g^?1 in sunflower bee pollen after UV radiation. In this study, 449 isolates belonging to 21 fungal species representing 9 genera were found in 45 samples of bee pollen. The total isolates were detected in frozen poppy pollen 29, rape pollen 40, sunflower pollen 80, in dried poppy pollen 12, rape pollen 36, sunflower 78, in poppy pollen after UV radiation treatment 54, rape 59 and sunflower 58. The most frequent isolates of microscopic fungi found in bee pollen samples of all prevalent species were Mucor mucedo (49 isolates), Alternaria alternata (40 isolates), Mucor hiemalis (40 isolates), Aspergillus fumigatus (33 isolates) and Cladosporium cladosporioides (31 isolates). The most frequently found isolates were detected in sunflower bee pollen frozen (80 isolates) and the lowest number of isolates was observed in poppy bee pollen dried (12 isolates). The most prevalent mycotoxin of poppy bee pollen was ZON (361.55 ± 0.26 μg.kg^?1), in rape bee pollen T-2 toxin (265.40 ± 0.18 μg.kg^?1) and in sunflower bee pollen T-2 toxin (364.72 ± 0.13 μg.kg^?1) in all cases in frozen samples.     

Effect of humic acids on photodegradation of chloroacetanilide herbicides under UV irradiation

The effects of two humic acids (HAs) of different origins on the photodegradation of the chloroacetanilide herbicides acetochlor, propisochlor and butachlor were investigated in this study. One of the tested HAs was a standard sample that was purchased from a commercial source, and the other was isolated from the black soil of Northeast China. The photolysis of all three herbicides followed pseudo-first-order kinetics under ultraviolet (UV) irradiation conditions, regardless of whether HAs were present or not. Both HAs improved the photolysis rates of acetochlor in a dose-reversed way, whereas they inhibited butachlor degradation under all experimental concentrations. The two HAs differed in their effects on propisochlor photolysis, changing from enhancement to inhibition, depending on the origin and concentration of HAs. Element and Fourier Transform Infrared spectroscopy analyses showed that the isolated HAs had more polysaccharides and less aliphatic groups than the commercial HAs, and it was indicated that some characteristic radicals (C═O, O─H and phenolic hydroxyls) in HAs were involved in the photolysis of the herbicides. Gas chromatography/mass spectrometry (GC/MS) analyses indicated that the presence of HAs had no effects on the photolysis pathway and photoproduct species of the three herbicides.