On ordered categories as a framework for fuzzification of algebraic and topological structures

Using the framework of ordered categories, the paper considers a generalization of the fuzzification machinery of algebraic structures introduced by Rosenfeld as well as provides a new approach to fuzzification of topological structures, which amounts to fuzzifying the underlying “set” of a structure in a suitably compatible way, leaving the structure itself crisp. The latter machinery allows the so-called “double fuzzification”, i.e., a fuzzification of something that is already fuzzified.     

Thermal characterization of piezoelectric and non-piezoelectric Lead Meta-Niobate

Powerful tools like Differential Scanning Calorimetry (DSC) and DTA seem to be under-utilized for the emerging materials for high temperature piezoelectric sensors, while thermal aspects of such piezoelectric phase change are also of theoretical interest. Curie temperature of Lead Meta-Niobate (PbNb₂O₆ or PN) is 570 °C, much higher than that for widely used lead zirconate titanate, making PN potentially more attractive at high temperatures. However, the only specific heat measurement for PN appears to be the 2–25 K study by Lawless, leaving the Curie temperature region unexplored. For PN, piezoelectricity is possible for the meta-stable orthorhombic structure only. So, we prepared pure phase orthorhombic PN by quenching (Q) and the rhombohedral PN by slow-cooling (S). We report for the first time, to our knowledge, DSC across the Curie temperature for Q and S types of PN. We find clear and interesting DSC signals at the Curie temperature in heating and cooling graphs for quenched (Q) PbNb₂O₆ only and none for the slow-cooled (S) PbNb₂O₆.     

具有DFT拓扑结构的有机-无机杂化材料(C2N2H10)[Zn2(PO4)2]的合成与结构表征

以氯化锌和磷酸为原料, 二亚乙基三胺(DETA)为模板剂, 通过水热法合成了一种具有空旷骨架结构的有机-无机杂化磷酸锌化合物. 晶体结构分析结果表明, 该化合物属于四方晶系, P42bc空间群, 晶胞参数a=b=1.46850(2) nm, c=0.89274(2) nm, α=β=γ=90°, V=1.92519(6) nm3, Z=8, Dc=2.641 g/cm3. 并对其进行了IR光谱和TG-DTA热分析研究. 荧光光谱分析结果表明, 化合物(C2N2H10)[Zn2(PO4)2]用451 nm的光激发时, 发射峰位置在665~688 nm之间.     

CH3SH…HOO开壳型氢键复合物的结构及其电子密度拓扑性质

在DFT-B3LYP/6-311++G**水平下求得CH3SH…HOO复合物势能面上的稳定构型. 计算结果表明, 在HOO以其O8—H7作为质子供体与CH3SH分子中的S5原子为质子受体形成的氢键复合物1和2中, O8—H7明显被“拉长”, 且其伸缩振动频率发生显著的红移, 红移值分别为330.1和320.4 cm-1; 在CH3SH分子以其S5—H6作为质子供体与HOO的端基O9原子为质子受体形成的氢键复合物3和4中, 也存在类似的情况, 但S5—H6伸缩振动频率红移不大. 经MP2/6-311++G**水平计算的4种复合物含BSSE校正的相互作用能分别为-20.81, -20.10, -4.46和-4.52 kJ/mol. 自然键轨道理论(NBO)分析表明, 在CH3SH…HOO复合物1和2中, 引起H7—O8键长增加的因素包括两种电荷转移, 即孤对电子n1(S5)→σ*(H7—O8)和孤对电子n2(S5)→σ*(H7—O8), 其中后者为主要作用. 在复合物3和4中也有相似的电荷转移情况, 但轨道间的相互作用要弱一些. AIM理论分析结果表明, 4个复合物中的S5…H7间和O9…H6间都存在键鞍点, 且其Laplacian量▽2ρ(r)都是很小的正值, 说明这种相互作用介于共价键和离子键之间, 偏静电作用为主.     

锂离子电池的合金电极材料的失效研究

采用电镀技术在铜箔上电镀金属锡, 并对其充放电过程中的厚度和结构的变化进行了观察和分析. 锡电极经过热处理后, 活性物质锡与基体铜相互扩散生成中间合金Cu6Sn5. 在合金电极嵌锂过程中, 由于有机电解液的分解, 形成了大量的锂氧化物, 这是合金电极体积膨胀的最主要的原因之一. 锂脱嵌后, 部分锂以Li2SnCu的形态保留在合金中, 造成了合金电极首次充放电的不可逆容量损失. 一些新型电解质的应用可能有助于降低合金电极材料体积的膨胀并提高其循环寿命.     

YVO4∶Sm3+红色发光材料的熔盐法合成与光谱性能

采用熔盐法合成了YVO4∶Sm3+红色发光材料. 用X射线粉末衍射对其结构进行表征, 证实样品为具有锆石结构的YVO4相; 测定了样品的激发与发射光谱; 分析了不同的掺杂浓度和烧结温度对样品发光强度的影响. 研究结果表明, 采用熔盐法合成的样品均可以产生Sm3+的特征发射, 但是与其它方法相比, 熔盐法合成样品位于647 nm处Sm3+的4G5/2-6H9/2发射明显得到加强, 从而使得样品发出明亮的红光, 而不是其它合成方法获得的橙色光. 当掺杂浓度为1%(摩尔分数)且在500 ℃下烧结5 h后, 熔盐法得到的YVO4∶Sm3+荧光粉的发光强度最大.     

Prediction of the vaporization enthalpy based on modified Randi? indices. I. Monohydric alcohols

The vaporization enthalpy of monohydric alcohols with different structures under normal conditions is calculated using a modified Randič method with an error comparable to the experimental one. The energy of hydrogen bonds in alcohols is determined and shown to be constant and independent on the alcohol structure. Original Russian Text Copyright ? 2009 by E. L. Krasnykh __________ Translated from Zhurnal Strukturnoi Khimii, Vol. 50, No. 3, pp. 577–581, May–June, 2009.     

Grafting of organosilane derived from 3-glycidoxypropyltrimethoxysilane and thiourea onto magnesium phyllosilicate by sol–gel process and investigation of metal adsorption properties

A layered inorganic–organic magnesium silicate (Mg-GTPS-TU) has been successfully synthesized by using sol–gel based precursor under mild temperature conditions and a new silylaing agent (GTPS-TU) derived from 3-glycidoxypropyltrimethoxysilane (GTPS) and thiourea (TU) as the silicon source. The hybrid material was characterized through elemental analysis, infrared spectroscopy, X-ray diffractometry, thermogravimetry, and carbon and silicon solid-state nuclear magnetic resonance spectroscopy. The result confirmed the attachment of organic functionality to the inorganic silicon network. The inter-lamellar distance for the hybrid material was found to be 18.8 Å. Metal adsorption characteristics follows Cr(III) >Mn(II)>Zn(II) with more affinity towards Cr(III) in dilute aqueous solution. Evaluation of thermodynamic parameters ΔH and ΔS for Cr(III) were found to be 25.44 J mol⁻¹ and 79.9 J mol⁻¹ K⁻¹, respectively, indicating adsorption process to be endothermic in nature. The negative value of ΔG indicated the feasibility and spontaneity of ongoing adsorption process at relatively higher temperature. The presence of multiple coordination sites in the attached organic functionality expresses the potentiality of the hybrid material containing new silylating agent for heavy cation removal from eco-system.     

General and facile synthesis of ceria-based solid solution nanocrystals and their catalytic properties

Uniform Ce_1−xZr_xO₂ (x=0.2–0.8) nanocrystals with ultra-small size were synthesized through a thermolysis process, facilitated by the initial formation of precursor (hydrated (Ce,Zr)-hydroxides) at low temperature. TEM, XRD, EDAX, and Raman spectra were employed to study the formation of the solid solutions with various Ce/Zr ratios. Ultraviolet–visible (UV–vis) spectra showed that the ratios of Ce³⁺ to Ce⁴⁺ in both surface and bulk for the as-prepared Ce_1−xZr_xO₂ nanocrystals increased with the zirconium content x. The well-distributed Zr and Ce in the hydrated (Ce,Zr)-hydroxides before their thermolysis became the crucial factor for the structural homogeneity of the products. In addition, this strategy was extended to the synthesis of Ce_1−xGd_xO_1−x/2, Ce_1−xSm_xO_1−x/2, and Ce_1−xSn_xO₂ solid solutions. Catalytic measurements indicated that the ceria-based catalysts were active for CO oxidation at temperatures beyond 250 °C and the sequence of catalytic activity was Ce_0.5Zr_0.5O₂>Ce_0.8Zr_0.2O₂>Ce_0.2Zr_0.8O₂>Ce_0.5Sm_0.5O_1.75.     

Optimization of FLEC-SPME for field passive sampling of VOCs emitted from solid building materials

The FLEC^®-SPME sampler, described in a previous paper, consists of an emission cell coupled with solid phase microextraction (SPME) for passive sampling of VOCs emitted from building materials. It represents an interesting alternative to standard dynamic sampling protocol as it is easier to implement. If standard dynamic sampling determines emission rates, passive FLEC^®-SPME aims to the determination of the concentration in air at the material surface. That could be assumed provided that material/air equilibrium is reached. Thus, VOCs emission kinetics were studied for 3 different materials (pine wood panel, carpet and PVC floor) to determine equilibrium times. Then, the relevance of the method has been assessed using new materials through a 3-day emission test. Qualitative results were compared to those obtained from the standard method to check the ability of FLEC^®-SPME to detect the most toxic compounds, named “VOCs of interest” and listed in the French regulation. Minor differences were observed, so this methodology seems promising, especially for field studies aiming in the identification of VOCs sources in buildings. Moreover, the concentration at the material surface combined to emission modeling could be used to predict indoor VOCs concentrations helping in indoor air quality diagnostic.