Isolation and identification of the <Emphasis Type="Italic">thermophilic alkaline desulphuricant</Emphasis> strain

A desulfurization strain that belongs to the thermophilic alkaline desulphuricant is designated as strain GDJ-3 and isolated from Inner Mongolia, China. The colony of the strain shows tiny, yellow, or white-yellow, and it becomes henna with the protracting of cultivated time. The cells are bacilliform (0.3−0.6 × 1.0−1.2 μm), motive, and Gram negative. The strain GDJ-3 is able to utilize respectively the thiosulphate, sulfate, sulfite, or sulfide as sulfur source, utilize the carbon dioxide as the carbon source, and utilize the ammonium or nitrate as the nitrogen source. According to GenBank data, 16s RNA results of GDJ-3 are in good agreement with Alpha proteobacterrium sp. (97%) and Ochrobactrum sp. (98%). For GDJ-3, the optimum growth temperature is at 45°C, the optimum pH is at 8.5–8.8, and the optimum rocking speed of sorting table is at 150 r/min. Under the optimum culture condition, the cells of the strain can live for about 18 h. In the desulfurization solution, which is prepared according to the composition of DDS solution, the objectionable constituents of sodium thiosulphate and sodium sulfide were added factitiously, and the bacterial cell concentration was set at 10⁷/mL. After the regeneration of the above desulfurization solution by the strain cells, the concentration of sodium thiosulphate was decreased by 14.75 g/L (percentage loss of content 13.21%), the concentration of sodium sulfide was decreased by 0.76 g/L (percentage loss of content 87.36%) in the desulfurization solution in 9.5 hours, and sulfur appeared. Maybe, this kind of strain can be used as the regeneration’s bacterial source of DDS solution.     

Photochemical fixation and reduction of sulfur dioxide to sulfide by tetraphenylporphyrin magnesium: Spectroscopic and kinetic studies

The photochemical reaction of sulfur dioxide(SO2) with tetraphenylporphyrin magnesium(MgTPP) has been investigated in dichloromethane(CH2Cl2) solution at room temperature with illumination by visible light.Conventional fluorescence,UV-vis,and MS spectral analyses showed that under these conditions,SO2 was initially photochemically fixed by MgTPP to form a 1:1 molecular adduct.On continued irradiation and maintaining the flow of SO2,MS and XRD results showed that MgTPP is remarkably effective in the photochemical reduction of SO2 to sulfide(S2).The kinetics of the photochemical reaction of MgTPP with SO2 was studied in a SO2-saturated solution.Under irradiation,the reaction follows pseudo first order kinetics for MgTPP,having a half-life decreasing from 106 to 57 min as the illumination intensity is increased from 350 to 600 Lm.This investigation of the photochemical fixation and reduction of SO2 by MgTPP is of key interest in elucidating fundamental photochemical reaction mechanisms associated with porphyrins in the presence of SO2 ;furthermore,the analysis of the photochemical reaction may offer new opportunities for the fixation and reduction of SO2 to less harmful species.     

滑线式电桥电阻测量条件和灵敏度数据处理的探讨

运用不确定度,推出了滑线式电桥测电阻的最佳测量条件,指出了该条件应用时出现的问题,提出了解决办法：另外对电桥灵敏度测量的等效方法给出了证明,对灵敏度数据处理方法进行了补充。     

Facile shape and size-controlled growth of uniform magnetite and hematite nanocrystals with tunable properties

Monodispersed magnetite Fe3O4 and hematite α-Fe2O3 nanocrystals have been grown in co-solvents of alcohol and water. Either the shape or the size of the nanocrystals could be easily controlled. Both the phases and nanostructures have been characterized by powder X-ray diffraction patterns and electron microscopy. The magnetic and catalytic properties of these products were investigated and compared with each other. The obtained results clearly demonstrate that these iron oxide nanocrystals are soft ferromag...     

Biological decomposition of Na_2S_2O_3 into sulfur by a newly isolated facultative thermophilic alkaline desulphuricant strain

A facultative thermophilic alkaline desulphuricant strain named GDJ-3 was isolated from neutral soils,enriched on sulfur synthetic medium,and detected in previous work.Conventional and chemotax-onomic analyses and 16s RNA gene sequencing showed that the strain was in good agreement with Alpha proteobacterium sp.(97%) and ochrobactrum sp.(98%).The regenerative processes of the solu-tion containing sulfur compounds(SCS) from the strain through an orthogonal test were investigated to get the optimum regenerati...     

Biological decomposition of Na<Subscript>2</Subscript>S<Subscript>2</Subscript>O<Subscript>3</Subscript> into sulfur by a newly isolated facultative thermophilic alkaline desulphuricant strain

A facultative thermophilic alkaline desulphuricant strain named GDJ-3 was isolated from neutral soils, enriched on sulfur synthetic medium, and detected in previous work. Conventional and chemotaxonomic analyses and 16s RNA gene sequencing showed that the strain was in good agreement with Alpha proteobacterium sp. (97%) and ochrobactrum sp. (98%). The regenerative processes of the solution containing sulfur compounds (SCS) from the strain through an orthogonal test were investigated to get the optimum regenerative condition. The results showed that regenerative temperature, air flow, and stirring speed of the agitator were the main three variables influencing the regenerative processes of the SCS. The optimum regenerative efficiency of the SCS from the strain was obtained when temperature, air flow, and stirring speed of the agitator were 318.2 K, 3.0 L/min, and zero r/min, respectively. Under this condition, when the cell concentration of the strain was adjusted to 10⁷/mL, the concentrations of Na₂S₂O₃ and Na2S in the SCS decreased from 112.68 g/L to 96.88 g/L and from 0. 87 g/L to 0.11 g/L in 9.5 h. Meanwhile, XRD spectrum shows that sulfur was formed in the regeneration process. These results suggest that the strain has potential application to the regeneration of the industrial solution containing sulfur compounds. Supported by Yongfeng Boyuan Industry Co., Ltd., Jiangxi Province, China     

Hydrogen bonding interactions between ethylene glycol and water: density,excess molar volume,and spectral study

Studies of the density and the excess molar volume of ethylene glycol (EG)-water mixtures were carried out to illustrate the hydrogen bonding interactions of EG with water at different temperatures. The re-sults suggest that a likely complex of 3 ethylene glycol molecules bonding with 4 water molecules in an ethylene glycol-water mixture (EGW) is formed at the maximal excess molar volume,which displays stronger absorption capabilities for SO2 when the concentration of SO2 reaches 400×10?6 (volume ratio) in the gas phase. Meanwhile,FTIR and UV spectra of EGWs were recorded at various EG concentra-tions to display the hydrogen bonding interactions of EG with water. The FTIR spectra show that the stretching vibrational band of hydroxyl in the EGWs shifts to a lower frequency and the bending vibra-tional band of water shifts to a higher frequency with increasing the EG concentration,respectively. Furthermore,the UV spectra show that the electron transferring band of the hydroxyl oxygen in EG shows red shift with increasing the EG concentration. The frequency shifts in FTIR spectra and the shifts of absorption bands in UV absorption spectra of EGWs are interpreted as the strong hydrogen bonding interactions of the hydrogen atoms in water with the hydroxyl oxygen atoms of EG.     

Binding of nucleosides with the cytotoxic plant alkaloid sanguinarine: Spectroscopic and thermodynamic studies

In spite of a large number of studies of the interaction of the cytotoxic plant alkaloid sanguinarine(SAN) with nucleic acids,the anticancer mechanism of SAN is still not clear.In contrast to the large number of studies of the interaction mechanism of SAN with DNA,there have been relatively few studies of the interaction of SAN with nucleosides.In this work,the interaction of SAN with three nucleosides-thymidine(T),uridine(U),and adenosine(A)-was investigated using a combination of conventional fluorescence and UV-vis spectroscopic techniques;thermodynamic calculations were also carried out at physiological pH 7.2.The binding processes of SAN with the different nucleosides were characterized by hypochromic and bathochromic effects in the absorption spectra of SAN and by the quenching of the fluorescence intensity of SAN.The measurements of fluorescence lifetime,the variations of the absorption spectra of the fluorophore,and the dependence of the quenching on the temperature indicated that the fluorescence quenching is static.The Stern-Volmer plot is nonlinear and approximately quadratic showing that,in this process,one SAN molecule can bind with two nucleoside molecules.These studies,together with our earlier studies of the binding of SAN with cytidine(C) and guanosine(G),showed that the binding constants of SAN with the five nucleosides at T = 308.15,318.15,and 328.15 K decreased in the order C > G > T > U > A and at T = 298.15 K decreased in the order G > C > T > U > A,and that the binding of SAN with the various nucleosides is not only slightly exothermic but also entropy-driven.All these results together with fluorescence quenching experiments advance good evidence concerning the interaction of SAN with various nucleosides.Such studies of the interaction mechanism of alkaloids with DNA may promote the development of new drugs.     

First dark matter search results from the PandaX-I experiment

We report on the first dark-matter (DM) search results from PandaX-I, a low threshold dual-phase xenon experiment operating at the China JinPing Underground Laboratory. In the 37-kg liquid xenon target with 17.4 live-days of exposure, no DM particle candidate event was found. This result sets a stringent limit for low-mass DM particles and disfavors the interpretation of previously-reported positive experimental results. The minimum upper limit, 3.7 × 10^?44 cm², for the spin-independent isoscalar DM-particle-nucleon scattering cross section is obtained at a DM-particle mass of 49GeV/c² at 90% confidence level.     

Luminescence mechanism and energy level structure of Eu-doped GaN powders investigated by cathodoluminescence spectroscopy

1.5at% Eu-doped GaN powders were prepared by a co-precipitation method.Powder X-ray diffraction(XRD)results shows that there is only the wurtzite phase.Cathodoluminescence spectra were measured at room temperature and liquid nitrogen temperature,respectively.The band-to-band luminescence of GaN was shifted from 373 nm to 368 nm with the temperature decreasing from room temperature to liquid nitrogen temperature.The luminescence peaks at 537,557,579,590,597,614,653 and 701 nm are attributed to the Eu ions related transitions in the host of GaN powders and the peak positions were not influenced by the variation of temperature.With the increase of accelerating voltage,the intensity of all luminescence peaks was increased.The strongest luminescence peak at 614 nm shows non-symmetrical shape and is composed of 612,615 and 621 nm through Lorentzian fitting,which indicates there are oxygen and nitrogen environments of the Eu3+ions in the Eu-doped GaN powders.