A comparative study of the structure and crystallization of bulk metallic amorphous rod Pr60Ni30Al10 and melt-spun metallic amorphous ribbon Al87Ni10Pr3

Pr-based bulk metallic amorphous （BMA） rods （Pr60Ni30Al10） and Al-based amorphous ribbons （Al87Ni10Pr3） have been prepared by using copper mould casting and single roller melt-spun techniques, respectively. Thermal parameters deduced from differential scanning calorimeter （DSC） indicate that the glass-forming ability （GFA） of Pr60Ni30Al10 BMA rod is far higher than that of Al87Ni10Pr3 ribbon. A comparative study about the differences in structure between the two kinds of glass-forming alloys, superheated viscosity and crystallization are also made. Compared with the amorphous alloy Al87Ni10Pr3, the BMA alloy Pr60Ni30Al10 shows high thermal stability and large viscosity, small diffusivity at the same superheated temperatures. The results of x-Ray diffraction （XRD） and transmission electron microscope （TEM） show the pronounced difference in structure between the two amorphous alloys. Together with crystallization results, the main structure compositions of the amorphous samples are confirmed. It seems that the higher the GFA, the more topological type clusters in the Pr-Ni-Al amorphous alloys, the GFAs of the present glass-forming alloys are closely related to their structures.     

含氢硅单晶2210cm-1红外吸收峰本质的理论研究——Ⅰ.振子频率的价键力场计算

本文根据Urey-Bradely 力场的思想,用价键力场的方法对文献[1]中提出的含氢硅单晶中2210cm^-1吸收峰对应的缺陷复合体的两个模型:空位+4H,间隙硅烷,进行了振动频率的计算.在对计算结果和力常数调节合理性分析的基础上,得出了空位+4H模型比较合理的结论.此外还介绍了理论计算揭示的从实验上区分两个模型的可靠途径.     

自由基CH(X2Π,a4Σ-)的光谱数据从头算研究

用分子轨道从头算方法,对CH自由基的基态(X2Π)和低激发态(a4Σ-)的光谱数据进行了计算.计算结果表明,在基态CH(X2Π)时,在QCISD(T)/6-311G (3df,3pd)水平上,计算所得的键长R=0.1120981nm,偶极矩μ＝1.5891 Debye,ν＝2845.43cm-1均与实验值相吻合,在B3PW91/6-311G (3df,3pd)理论水平上,计算的基态能量为-38.496143 Hartree,误差仅为0.22%;对低激发态CH(a4Σ-),使用含时的密度泛函方法(TDDFT)和大基组6-311 G(3df,3pd)计算所得的R=0.1094nm,垂直跃迁能量为0.926eV,均与实验结果有较好的吻合.     

Self-supported metal sulphide nanocrystals-assembled nanosheets on carbon paper as efficient counter electrodes for quantum-dot-sensitized solar cells

Developing efficient counter electrodes (CEs) and quantum dots made of earth-abundant and non-toxic elements is essential but still challenging for quantum dot-sensitized solar cells (QDSSCs). Here, we report a facile strategy to prepare self-supported and robust CoS₂ and NiS nanocrystals-assembled nanosheets directly grown on carbon paper (MSx NS@CP) as efficient counter electrodes for QDSSCs. Such CEs integrate the merits of fast electron transfer from interconnected conductive scaffold, efficient mass transfer from hierarchically vertical nanosheet on 3D open substrate, as well as abundant highly active catalytic sites from metal sulphide nanocrystal units. As a result, QDDSCs based on such CoS₂ NS@CP and NiS NS@CP CEs achieve a PCE of 8.88% and 7.53%, respectively. The detailed analyses suggest that CoS₂ NS@CP has the highest catalytic activity and shows the lowest charger transfer resistance, leading to the highest PCE. These findings may inspire the design and exploration of other self-supported efficient CEs by integrating highly active catalysts onto 3D conductive networks for efficient QDSSCs.     

磁控溅射制备W掺杂VO2/FTO复合薄膜及其性能分析

为了获得相变温度低且热致变色性能优越的光学材料, 室温下在F:SnO₂ (FTO)导电玻璃基板表面沉积钨钒金属膜, 再经空气气氛下的热氧化处理, 制备了W掺杂VO₂/FTO复合薄膜, 利用X射线光电子能谱、X射线衍射和扫描电镜对薄膜的结构和表面形貌进行了分析. 结果表明: 高温热氧化处理过程中没有生成W, F, V混合氧化物, W以替换V原子的方式掺杂. 与采用相同工艺和条件制备的纯VO₂/FTO复合薄膜相比, W掺杂VO₂薄膜没有改变晶面取向, 仍具有(110)晶面择优取向, 相变温度下降到35 ℃左右, 热滞回线收窄到4 ℃, 高低温下的近红外光透过率变化量提高到28%. 薄膜的结晶程度明显提高, 表面变得平滑致密, 具有很好的一致性, 对光电薄膜器件的设计开发和工业化生产具有重要意义. 关键词： W掺杂 2')" href="#">VO₂ FTO导电玻璃 磁控溅射     

煤粉燃烧过程碳烟生成的激光测量研究

燃煤锅炉生成的碳烟不仅会增强火焰辐射、影响燃烧外,还排放到大气环境中带来严重危害。为了进一步了解其生成机理从而更好地对其生成量及特性进行控制,对煤粉燃烧过程中颗粒周围碳烟的分布规律进行定量的研究十分必要。本文自行设计了注射式微量给粉装置,成功实现了0.1 g/h量级给粉率下的连续给粉,并通过改进多元扩散燃烧器和以及结合激光诱导白炽光(Laser Induced Incandescence)技术,首次实现了对单颗粒煤粉燃烧过程中碳烟分布的定量测量,发现对于70μm左右的煤粉颗粒,碳烟分布直径约为1 mm。此外还通过控制气氛,研究了含氧量对碳烟生成的影响,发现随着氧含量的上升,碳烟总浓度下降并且峰值出现更早的规律。     

Heavy Metal Resistances and Chromium Removal of a Novel Cr(VI)-Reducing Pseudomonad Strain Isolated from Circulating Cooling Water of Iron and Steel Plant

Three bacterial isolates, GT2, GT3, and GT7, were isolated from the sludge and water of a circulating cooling system of iron and steel plant by screening on Cr(VI)-containing plates. Three isolates were characterized as the members of the genus Pseudomonas on the basis of phenotypic characteristics and 16S rRNA sequence analysis. All isolates were capable of resisting multiple antibiotics and heavy metals. GT7 was most resistant to Cr(VI), with a minimum inhibitory concentration (MIC) of 6.5 mmol L^?1. GT7 displayed varied rates of Cr(VI) reduction in M2 broth, which was dependent on pH, initial Cr(VI) concentration, and inoculating dose. Total chromium analysis revealed that GT7 could remove a part of chromium from the media, and the maximum rate of chromium removal was up to 40.8 %. The Cr(VI) reductase activity of GT7 was mainly associated with the soluble fraction of cell-free extracts and reached optimum at pH 6.0～8.0. The reductase activity was apparently enhanced by external electron donors and Cu(II), whereas it was seriously inhibited by Hg(II), Cd(II), and Zn(II). The reductase showed a K _m of 74 μmol L^?1 of Cr(VI) and a V _max of 0.86 μmol of Cr(VI) min^?1 mg^?1 of protein. The results suggested that GT7 could be a promising candidate for in situ bioremediation of Cr(VI).     

含氢硅单晶2210cm-1IR峰本质的理论研究——Ⅲ.峰型的温度效应和缺陷的对称性破缺

本文研究表明,除了200K附近异常峰宽外,2210cm^-1IR峰峰宽均是由声子散射和剩余峰宽决定。对于200K附近峰宽、峰型的异常变化,提出了该峰对应缺陷中心由低温的T_d对称性向高温的D_2d对称性转变的机制。计算表明,空位+4H模型确实具有两种状态:低于200K的T_d稳态和D_2d亚稳态及高于200K的D_2d稳态和T_d亚稳态。对称性破缺机制所给出的结果不仅在定性上,而且在定量上都能与实验相符,这证明V+4H是2210cm^-1IR峰对应的缺陷中心具有较高的可信度。     

A pair of enantiomeric 5-oxabicyclic[4.3.0]lactam derivatives and one new polyketide from the marine-derived fungus Penicillium griseofulvum

A pair of enantiomeric 4-oxabicyclic[4.3.0]lactam derivatives, (+)- and (?)-penicilactam A (1), and one new polyketide derivative penicitrinone F (2) were isolated from the marine-derived fungus Penicillium griseofulvum GT-10. Their structures and absolute configurations were elucidated through extensive spectroscopic analyses combined with the calculated ECD spectra. Penicitrinone F (2) had moderate inhibitory activity towards Bacillus subtilis with a MIC value of 6.3 μM.     

A nanofiber mat prepared from sulfonated polyaniline for solid-phase extraction of fluoroquinolones from water and biological fluids prior to their quantitation by UPLC-MS/MS

Microchimica Acta - A core-shell structured magnetic covalent organic frameworks of the type Fe3O4@COFs was prepared by using the Fe3O4 nanoparticles as magnetic core, and...