在多太瓦Ti：蓝宝石激光作用下获得高能电子和X射线量子

使用应用光学实验室和马克斯·玻恩研究所的多太瓦Ti：蓝宝石激光器在宽度～30fS，强度10^18～10^19W／cm^2的激光脉冲照射钨靶和钽靶时研究了电子和硬X射线量子产额以及它们的能量分布。在应用光学实验室测量15～700keV范围硬X射线量子通量时使用了具有校准的热致发光探测器的九通道谱仪。在一个数量级范围内入射激光能量和脉冲宽度改变五倍时研究了硬X射线量子的定标。在玻恩研究所新Ti：蓝宝石激光器上借助飞行时间谱仪研究了300keV～1MeV范围的热电子产额。所获结果表明电子产额与激光脉冲的强度和形状的强依赖关系。

Curved crystal spectrometer for the measurement of X-ray lines from laser-produced plasmas

In order to diagnose the laser-produced plasmas, a focusing curved crystal spectrometer has been developed for measuring the X-ray lines radiated from a laser-produced plasmas. The design is based on the fact that the ray emitted from a source located at one focus of an ellipse will converge on the other focus by the reflection of the elliptical surface. The focal length and the eccentricity of the ellipse are 1350 mm and 0.9586, respectively. The spectrometer can be used to measure the X- ray lines in the wavelength range of 0.2-0.37 nm, and a LiF crystal （200） （2d = 0.4027 nm） is used as dispersive element covering Bragg angle from 30° to 67.5°. The spectrometer was tested on Shengnang- Ⅱ which can deliver laser energy of 60-80 J/pulse and the laser wavelength is 0.35 μm. Photographs of spectra including the 1 s2p ^1P1-1s^2 ^1S0 resonance line（w）, the 1s2p ^3P2-1s^2 1S0 magnetic quadrupole line（x）, the 1s2p ^3P1-1 s^2 ^1S0 intercombination lines（y）, the 1 s2p ^3S^1-1 s^2 ^1S0 forbidden line（z） in helium-like Ti Ⅹ Ⅺ and the 1 s2s2p ^2P3/2-1 s622s ^2S1/2 line（q） in lithium-like Ti Ⅹ Ⅹhave been recorded with a X-ray CCD camera. The experimental result shows that the wavelength resolution（λ/△ 2） is above 1000 and the elliptical crystal spectrometer is suitable for X-ray spectroscopy.

Some Transition Metal Complexes Bearing Artemisinin Derivatives and （N-N-O） Tridentate Chromium （Ⅲ） Complexes Ligated by 2-benzolmidazo-yl-6-acetyl. pyridines for Catalytic Behaviour towards Ethylene

Interventions of metal complexes in the area of metallopharrneceutical and polymer sciences play a great economic importance to human challenges. Complexation behavior of some artemisinin derivatives with late transition metals and chromium-benzoimidazoylpyridine analogues have been investigated. The Fe（Ⅲ）, Zn（Ⅱ） and Cd（Ⅱ） complexes of artesunate and artemether and that of chromium-benzimidazoyl pyridine were synthesized with molar ratio of metal to ligand between 1：1 and 1：2. Structural elucidation using X-ray analysis and other characterization of the complexes （AAS, IR, UV, E.A, NMR） were carried out to explore the coordination affinity of them viz-a viz bonding, geometries and elemental composition. The IR absorption revealed that artesunate acts as monodentate specie through carbonyl group on coordination. However, its bidentate mode was also observed with carboxylic group acting as C=O and C-O bonding when deprotonation happened. Artemether （L2） was synthesized using artesunate and its structure was confirmed by single crystal X-ray crystallography as well as its Zn（Ⅱ） complex exhibiting a square planar geometry. A series of 2-benzoimidazoylpyridine derivates （L3-L6） and their chromium complexes were synthesized and characterized. In the presence of methylaluminoxane （MAO）, all chromium complexes show good activity for ethylene oligomerization and polymerization whereas with diethylaluminium chloride （Et2AlCl2） the complexes show moderate activity. The distribution of oligomers obtained follows Schulz- Flory rules with high selectivity for α-olefins. The combined productivity （meaning both activities of ethylene oligomerization and polymerization） are improved with increasing ethylene pressure. The results show that the reaction conditions greatly affect the properties of the polymer such as molecular weight distribution and melting point（Tm） with extremely broad molecular weight distributions. With elevating reaction temperature from 0 to 60 ℃, the melting point （Tin） of resultant polyethylene decreased rapidly from 134 ℃ to 70 ℃.

Improvement of Magnetic Field on Tribological Properties of Lubricating Oils with Zinc Butyloctyldithiophosphate

Tribological properties of 150 SN mineral oil and the oils doped with different contents of zinc butyloctyldithiophosphate(T202) under magnetic field or non-magnetic field were evaluated on a four-ball tribotester by applying an external magnetic field around the friction region. Moreover, the morphology and the tribochemical characteristics of worn surfaces were examined by a scanning electron microscope(SEM) and an X-ray photoelectron spectrometer(XPS). Then the lubrication mechanisms were discussed. The tribological test results indicated that the wear scar diameters(WSDs) of steel balls lubricated by the T202-containing lubricating oils and the friction coefficients of the corresponding oil under magnetic field were smaller than those without magnetic affection. The worn surface lubricated with the T202-formulated oils in a magnetic field was smoother than that obtained under the normal condition. Furthermore, the results of XPS analysis indicated that tribochemical films on the surfaces lubricated with T202-doped oils were mainly composed of compounds such as FeSO_4, FeS and ZnS. The atomic concentrations of oxygen, sulfur, iron, zinc and phosphorus species identified in T202 under magnetic field were higher than those without magnetic impact. It can be inferred that the improved anti-wear and friction-reducing ability of T202-doped oils was attributed to the promoted tribochemical reactions and the modification of the worn surfaces induced by magnetic field.

Luminescence Properties of Green-emitting Phosphors-Sr4Al14O25：Eu2＋ for LED Applications

A highly intense green-emitting phosphor of Eu2＋-doped Sr4Al14O25 （SAE：Eu2＋） was synthesized by a solid state reaction. In this study, XRD, PL/PLE, QE, thermal stability and LED package tests are systematically carried out and investigated. The optimized-composition of （Sro 92Eu0.08）4Al14025 exhibited a green emission peak at 497 nm under excitation wavelength of 400 nm, giving the chromaticity coordinates of （0.14, 0.35） with excellent quantum efficiency （98%） compared to those of other green-commodities, such as Ba2SiO4：Eu2＋ （90%） and BaMgAl10O17：EU2＋, Mn2＋ （92%）. The results demonstrated that SAE：Eu2＋ could be a potential candidate as the NUV-pumping phosphor for applications in light-emitting diodes （LEDs）.

Development of Biotechnology for Microbial Synthesis of Gold and Silver Nanoparticles

Several bacterial strains of Actinomycetes belonging to Streptomyces and Arthrobacter genera for the first time were used to study the biotechnology of synthesis of gold and silver nanoparticles. The experimental conditions of gold and silver nanoparticles production by the cells of studied strains in aqueous chloroauric acid （HAuCIq） and in silver nitrate （AgNO3） solutions, respectively, were determined. Concentration and time-dependences of nanoparticle formation were investigated. The complex of optical and analytical methods was used for testing the gold and silver nanoparticles in the bacterial biomass. The TEM （Transmission Electron Microscopy） and XRD （X-ray Diffraction） data in all cases demonstrated the presence of crystals with fcc （face centered cubic） structure. The results obtained show that the Actinomycetes are capable of producing gold and silver nanoparticles of spherical shape extracellularly when exposed to suitable compounds. The particle size distribution shows that the sizes of nanoparticles are in the range of 5 nm to 80 nm. The biomass obtained may be used for industrial as well as medical and pharmaceutical purposes.

Synthesis and Structural Characterization of Sm-Sr Nickelates

The main purpose of this work was to obtain Sm-Sr nickelates nanoparticles with Ruddelsden-Popper type structures obtained by a simple process such as gelatin synthesis. The powders were calcinated at 900 ℃ and characterized by X-ray diffraction, thermogravimetric analysis, scanning electron microscopy and high-resolution transmission electron microscopy techniques. The effect of chemical substitution of the Sm^3＋ by Sr^2＋ ions on the structural properties of the powders was studied. The Rietveld＇s method was successfully applied for determination of the quantitative phase analysis of the powders and revealed that the main phase of the powders for different strontium content is of Ruddelsden-Popper type structure. A symmetry change from orthorhombic to tetragonal is observed as increasing strontium.

Structure,magnetic properties and magnetocaloric effects of Fe_(50)Mn_(15-x)Co_xNi_(35) alloys

FesoMn15-xCoxNi35 （x=0, 1, 3, 5, 7） alloys were prepared by arc melting under purified argon atmosphere. The ingots were homogenized at 930℃ for 90 h followed by water quenching. The crystal structure, magnetic properties and magnetocaloric effects of the alloys were studied by X-ray diffraction （XRD） and MPMS-7-type SQUID. The results show that all samples still maintained a single γ-（Fe, Ni）-type phase structure. With the increase of the content of Co, the Curie temperatures of these alloys increased and exhibited a second-order magnetic transition from ferromagnetic （FM） to paramagnetic （PM） state near Curie temperature. The maximum magnetic entropy change and the relative cooling power of Fe50Mn10CosNi35 alloy was 2.55 J/kg.K and 181 J/kg, respectively, for an external field change of 5 T. Compared with rare earth metal Gd, FesoMnls-xCoxNi35 series of alloys have obvious advantage in resource price; their Curie temperatures can be tuned to near room temperature, maintain a relatively large magnetic entropy change at the same time and they are a type of potential magnetic refrigeration materials near room temperature.

Effects of the ZnO buffer layer and Al proportion on AZO film properties

To evaluate the influence of the ZnO buffer layer and A1 proportion on the properties of ZnO： A1 （AZO）/ZnO bi-layer films, a series of AZO/ZnO films are deposited on the quartz substrates by electron beam evaporation. The X-ray diffraction measurement shows that the crystal quality of the films is improved with the increase of the film thickness. The electrical properties of the films are investigated. The carrier concentration and Hall mobility both increase with the increase of buffer layer thickness. However, the resistivity reaches the lowest at about 50 nm-thick buffer layer. The lowest resistivity and the maximum Hall mobility are both obtained at 1 wt% Al concentration. But the optical transmittance of all the films is greater than 80% regardless of the buffer layer thickness with A1 concentration lower than 5 wt% in the visible region.

Enhanced visible-light photocatalytic activity of a g-C_3N_4/m-LaVO_4 heterojunction: band offset determination

Band offset is a dominant factor affecting the photocatalytic performance of heterostructure photocatalysts. Therefore, controlling the band gap structure of semiconductors is a key challenge in the development of efficient photocatalysts. We used a typical in situ-method to prepare diverse graphite-phase carbon nitride(g-C_3N_4)samples from melamine, thiourea, and a mixture thereof,and found that they exhibited band gaps between2.3–2.8 e V. From UV–Vis spectra and X-ray photoelectron spectroscopy measurements, we determined that the g-C_3N_4 samples exhibited different band gap values and valence band positions. On this basis, we constructed g-C_3N_4/m-La VO_4 heterojunctions with different band offsets. UV–Vis spectra and X-ray photoelectron spectroscopy measurements revealed that the valence band offsets(VBOs) of the different heterojunctions were similar, but their conduction band offsets(CBOs) were significantly different. Photocatalytic experiments revealed that the reaction rate was enhanced with an increase in the CBO value. Furthermore, the three-phase g-C_3N_4/g-C_3N_4/mLa VO_4 heterojunction composed of m-La VO_4 and mixed g-C_3N_4 showed the highest photocatalytic activity, which was mainly due to the construction of a multilevel structure. This work investigates the influence of the band offset on heterojunction photoelectrochemical properties and provides a new strategy to improve the photocatalytic activity by constructing multilevel structures.

Removal of trace Cr(VI) from water using chitosan-iron nanowires in porous anodic alumina

Chitosan-iron nanowires in porous anodic alumina （PAA） have been successfully prepared under ambient conditions as an ad- sorbent. The adsorbent was characterized by scanning electron microscopy, X-ray photoelectron spectroscopy and N2-BET surface area. The results showed that PAA can disperse and protect Fe0 nanorods from oxidation. The adsorption characteris- tics of trace Cr（VI） onto adsorbent have been examined at different initial Cr（VI） concentrations with pH 5. Batch adsorption studies show that the removal percentage of adsorbent for the removal of trace Cr（VI） is strongly dependent on the initial Cr（VI） concentrations. Langmuir and Freundlich isotherm models were used to analyze the experiment data. The adsorption of trace Cr（VI） by adsorbent is well modeled by the Langmuir isotherm and the maximum adsorption capacity of Cr（VI） is calcu- lated as 123.95 mg/g which is very closed to the experiment results. Intraparticle diffusion study shows that the intraparticle diffusion of adsorbent is not the sole rate-controlling step. The negative value of Gibbs free energy change,△G0, indicated that the process of Cr（VI） onto adsorbent was spontaneous. This work has demonstrated that chitosan-iron nanowires in porous anodic alumina as an adsorbent has promising potential for heavy metal removal at trace level.

Cementing mechanism of bio-phosphate cement

Cementing mechanism of bio-phosphate cement was investigated by Fourier transform infrared spectroscopy(FTIR), X-ray photoelectron spectroscopy(XPS), thermogravimetric-differential scanning calorimetry(TG-DSC) analysis and scanning electron microscopy(SEM). The results of FTIR and XPS show that Si-O bond and Si(2p) electron binding energy in sandstone cemented via chemical and microbiological methods are changed by the binding effects of barium hydrogen phosphate with quartz sand. Compared with barium hydrogen phosphate precipitated in solution, there were higher decomposition temperatures or melting points in sandstone. The FTIR, XPS, and TG-DSC results indicate that the microbial-induced and chemical precipitation of barium hydrogen phosphate can interact with quartz sand to generate van der Waals bond, which plays a role in the binding function between loose sand particles and barium hydrogen phosphate. SEM results show that barium hydrogen phosphate after chemical precipitation in sandstone has better dispersion than microbiological deposition. Therefore, barium hydrogen phosphate via chemical precipitation did not bind loose sand particles into sandstone.

Photophysical properties of heteroaromatic ring-fused(di)benzosiloles

Benzosiloles fused to heterocycles such as thiophene, benzothiophene, and benzofuran, and indole- and benzosilole-fused dibenzosiloles were prepared by palladium-catalyzed intramolecular coupling of the corresponding 2-（arylsilyl）aryl triflates in good to high yields. Molecular and crystal structures of 5,7-dihydro-5,5,7,7-tetrakis（1-methylethyl）bis[1]benzosilolo-[2,3-b：3＇, 2＇-d]thiophene, 6-methyl-12,12-diisopropyl-12H-indololo[3,2-b][1]silafluorene, and 5,5,11,11-tetraisopropyl-5,11H-benzosilolo[3,2-c]silafluorene were determined by X-ray diffraction analysis. The UV absorption spectra of the （di）benzosilole derivafives in cyclohexane red-shifted when compared to 1,1-diisopropyldibenzosilole, indicating that replacing a benzene ring of dibenzosilole by the heterocycles as well as fusion of indole and benzosilole moieties onto dibenzosilole narrowed the HOMO- LUMO gaps of the n-conjugation system. The thiophene-fused benzosiloles were faintly fluorescent in solution and in the solid state, whereas the dibenzosiloles exhibited luminescence with moderate and high quantum yields in cyclohexane and in microcrystals, respectively. In other words, aggregation-induced emission was observed for the dibenzosiloles. Notably, 5,5,11,1 1- tetraisopropyl-5,11H-benzosilolo[3,2-c]silafluorene in microcrystals exhibited violet fluorescence （λmax = 396 nm） with a quantum yield of 0.70. Density functional theory （DFT） calculations of the prepared （di）benzosiloles were also performed.