The Application of NMR Spectroscopy and Chemometrics in Authentication of Spices

Spices and herbs are among the most commonly adulterated food types. This is because spices are widely used to process food. Spices not only enhance the flavor and taste of food, but they are also sources of numerous bioactive compounds that are significantly beneficial for health. The healing effects of spices are connected with their antimicrobial, anti-inflammatory and carminative properties. However, regular consumption of adulterated spices may cause fatal damage to our system because adulterants in most cases are unhealthy. For that reason, the appropriate analytical methods are necessary for quality assurance and to ensure the authenticity of spices. Spectroscopic methods are gaining interest as they are fast, require little or no sample preparation, and provide rich structural information. This review provides an overview of the application of NMR spectroscopy combined with chemometric analysis to determine the quality and adulteration of spices.     

封闭异氰酸酯几种反应的动力学

封闭异氰酸酯广泛地应用于各种单组分涂料、粉末涂料和胶粘剂中。近年来,随着人们对水性聚氨酯的重视和开发,封闭异氰酸酯的重视和使用程度进一步加大。本文对封闭异氰酸酯的相关反应的动力学进行了综述,对两种不同的反应机理及其动力学的影响因素作了介绍。     

油页岩中微量元素赋存形态的研究

通过浮沉实验及脱灰实验对抚顺、龙口、茂名3种油页岩样中部分微量元素进行了赋存形态的研究。结果表明,浮沉实验所得微量元素的赋存状态结果与脱灰实验基本一致,抚顺、龙口、茂名3种油页岩中大部分微量元素以无机态赋存,但也有所区别,抚顺、龙口、茂名油页岩中的元素V、Mn、Zn、Sr、Mo、Ta以及抚顺油页岩中的Cr、Te,龙口油页岩中的Cd、Sn,茂名油页岩中的Cd、Sn、Pb,主要赋存于无机矿物中;茂名油页岩中的Cr、Te,抚顺油页岩中的Cd,龙口油页岩中的Pb有相对较多的比例富集于有机质部分;龙口、茂名油页岩中的元素Co,抚顺油页岩中的Co、Sn、Pb,更多地富集于黏土矿中,但也有少部分富集于有机质中。     

Densities,speeds of sound,excess volumes and viscosities of binary mixtures of mtbe with tetralin and decalin at 303.15 k

Measurements of densities, speeds of sound, excess volumes and viscosities of binary mixture of methyl tert-butyl ether with tetralin and decalin are reported at 303.15?K over the entire range of composition. Excess volumes are measured using batch dilatometer technique. Sound speeds are obtained using ultrasonic interferometer. Densities are computed from excess volume data. Isentropic compressibilities are derived from density and sound speed data. Speeds of sound are evaluated on the basis of Jacobson's free length theory and Schaff's collision factor theory. The predicted values are in good agreement with the experimental results. The viscosity data are analysed on the basis of corresponding states approach. Excess volumes and deviation in isentropic compressibilities are negative and deviation in viscosities are positive over the entire composition range. The experimental results are discussed in terms of possible molecular interactions between unlike molecules.     

Importance of the catalytic effect of the substrate in the functionality of lubricant additives: the case of molybdenum dithiocarbamates

Molybdenum dithiocarbamates (MoDTCs) are lubricant additives very efficient in reducing the friction of steel, and they are used in a number of industrial applications. The functionality of these additives is ruled by the chemical interactions occurring at the buried sliding interface, which are of key importance for the improvement of the lubrication performance. Yet, these tribochemical processes are very difficult to monitor in real time. Ab initio molecular dynamics simulations are the ideal tool to shed light on such a complicated reactivity. In this work, we perform ab initio simulations, both in static and tribological conditions, to understand the effect of surface oxidation on the tribochemical reactivity of MoDTC, and we find that when the surfaces are covered by oxygen, the first dissociative steps of the additives are significantly hindered. Our preliminary tribological tests on oxidized steel discs support these results. Bare metallic surfaces are necessary for a stable adsorption of the additives, their quick decomposition, and the formation of a durable MoS₂ tribolayer. This work demonstrates the importance of the catalytic role of the substrate and confirms the full capability of the computational protocol in the pursuit of materials and compounds more efficient in reducing friction.     

煤微组分结构的X-射线实验研究

本文介绍用X-射线研究烟煤的壳质组、镜质组和惰质组三种煤微组分的结构。结果表明,不同微组分的结构存在差异,这是由于其化学组成不同而决定的。     

Extension of semiempirical methods to simulation of surfaces

Various approaches for surface simulation are described. They are based on free, saturated, and embedded clusters, as well as periodic models. The features of semiempirical methods are reviewed and ideas for their improvement are discussed. Special features of the structure and stability of clusters are presented which are suitable for the transition to the solid state. Linear and nonlinear relationships for binding energies and bond lengths in dependence of the average coordination number are discussed. Finally, a systematic way for the simulation of adsorption at ion crystal surfaces by model clusters is suggested. © 1996 John Wiley & Sons, Inc.     

纳米SiO2的表面处理及其在聚合物基纳米复合材料中的应用进展

简要介绍了纳米二氧化硅(SiO2)粒子的制备方法、结构和特性,对近年来国内外纳米SiO2的表面处理方法及聚合物/SiO2纳米复合材料的制备方法进行了阐述,并针对不同改性方法和制备方法的特点加以分析比较;讨论了SiO2粒子的分散机理和增强机理,并对未来的研究内容及方向提出展望。     

CO在Pd系双金属及其单金属催化剂上的吸脱附红外光谱

红外光谱表明吸附在担载于Al_2O_3上的Pd-Cu、Pd-Ag、Pd-Co和Pd-Pt 双组分催化剂上的CO仍保持其在单金属上的主要吸附物种,但其部分CO吸收带发生位移,吸附的CO易于脱附.CO在还原态Pd-Cu和Pd-Ag双金属催化剂上以吸附于Pd上者为主,其吸收带明显变弱而更易脱附.在Pd- Pt和Pd-Co氧化和还原态催化剂上CO桥式和线式吸收带强度比发生显著变化.似乎在这二类双金属催化剂上的几何结构效应比电子配位效应更为明显.     

超声技术在纳米材料制备中的应用

对超声技术在纳米材料制备中的应用与研究进展作了比较全面的综述,着重介绍了与超声有关的纳米材料制备方法,包括雪声雾化－热分解法,金属有机物超声热分解法,化学沉淀法和声电化学法,并就这些方法中声化作用的机理,特点和影响因素进行了讨论。     

Analytical applications of ternary complexes-VII Elucidation of mode of formation of sensitized metal-chelate systems and determination of molybdenum and antimony

The ternary complexes which are formed when surface-active agents are added to various metal-dyestuff chelate systems are shown to be dependent on the formation of micelles. Spectrophotometric measurements indicate that true ternary complexes are formed with well defined structures and that the changes in absorption spectra produced are not due to simple adsorption of the binary metal-dye complex onto micellar aggregates. Some suggestions are made to account for the nature of the observed changes. The analytical potentialities of this type of system are illustrated by the formation of such complexes between molybdenum or antimony, Catechol Violet and cetyltrimethylammonium bromide, yielding molar absorptivities of 4.6 × 10⁴ and 3.0 × 10⁴ respectively.     

Alternate multi-layered adsorption of macro-cations and -anions on the colloidal spheres. Influence of the deionization of the complexation mixtures with coexistence of the ion-exchange resins

The alternate multiple adsorption layers of macrocations and macroanions on the surfaces of colloidal spheres, in which the complexation mixtures are deionized with ion-exchange resins are studied with help of the electrophoretic light-scattering, dynamic light-scattering and transmitted electron-microscopy techniques. The results are compared with those without resins. Colloidal silica spheres (110 nm in diameter) and monodispersed polystyrene spheres (220 nm) are used as colloidal spheres. The macrocations used are poly (4-vinyl-N-n-butyl pyridinium bromide) and poly (allylamine hydrochloride). Sodium poly (styrene sulfonate) and sodium polyacrylate are used as macroanions. The macroion-colloid complexations are formed firmly when the complexation suspensions are deionized with the resins.     

大面积功率器件软钎料的焊接失效分析

针对大面积功率器件软钎料的失效问题,运用扫描电子显微镜(SEM)分析了SnPb软钎料的微观结构并运用能谱仪对其进行成分分析,找出了失效的主要原因:对软钎料进行刚玉抛光后,未能将残留在软钎料内的Al2O3成分完全去除,以至于器件的可焊性变差.根据分析提出了改进意见,较好地解决了SnPb软钎料的失效问题.     

燃油脱硫技术研究进展

综述了燃油脱硫技术的研究进展.介绍了燃油中硫含量的现状和国内外标准,重点阐述了脱硫工艺的开发和应用情况,列举了加氢脱硫、氧化脱硫、吸附脱硫等主要脱硫工艺的研究现状;并就燃油脱硫工艺技术的发展提出了建议.     

解读《有机化合物命名原则-2017》 ——新老命名原则的比较及常见取代基的命名

The differences between "Nomenclature of Organic Compounds-2017" and "Nonmenclature of Organic Chemistry (1980)" issued by Chinese Chemical Society are described. The general principles and numbering methods for naming substituent groups commonly used in organic chemistry for undergraduates are analyzed and explained; the proper systematic names are recommended to benefit classroom teaching and academic communication. Moreover, the principles such as systemization, standardization, simplification, uniformization, and "looking afterward" are proposed. Some recommendations are further presented:1) numbering the carbon skeleton of the substituent without compulsory numbering rule always begins at the point of attachment; 2) only preserving a minority of trivial names (common names); 3) naming methanoyl (formyl)-analogue groups following the name of methanoyl.     

Schemes of calculation of the properties of substituted ethylenes

Calculation schemes for estimation of the properties of X-substituted ethylenes based on the concept of atoms interacting in pairs are described. The equivalence of these schemes are shown, and the relations between their parameters are established.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 10, pp. 2586–2587, October, 1996.     

Successive construction of cellulase hyperproducers of Trichoderma using hyperpolyploids

When the swollen conidia of Trichoderma reesei QM 6a are treated with 0.1% (w/v) colchicine solution, huge autopolyploid nuclei can be formed in those swollen conidia. When a mycelial mat derived from such a conidum is treated with a haploidizing reagent, benomyl, many fan-shaped sectors are produced from the colony, and cellulase hyperproducers are selected from conidia on the colony. When colchicine and benomyl treatments are repeated on cellulase hyperproducers, new hyperproducers can be constructed successively and systematically. Moreover, when conidia derived from autopolyploids are treated with ethylmethanesulfonate solution, another type of cellulase hyperproducers (polyploids) can be obtained.     

A perturbative calculation of the rovibrational energy levels of methane

The rovibrational energy levels of methane are determined from a quartic ab initio potential energy force field where the expansion coordinates are the Morse coordinates for the stretches and extension coordinates for the bends. Energies are calculated using canonical Van Vleck perturbation theory. Results are obtained for both rotation-vibration Hamiltonians expressed as functions of curvilinear and rectilinear normal coordinates. Second, fourth, and sixth order curvilinear results are compared with experimental results, and fourth order results for the rectilinear and curvilinear Hamiltonian are compared to each other. The calculated rovibrational levels are in good agreement with the experimental values for low J levels. The calculated rotational level splittings are in even better agreement with the experiment. In particular, the ground state tetrahedral splittings, which are as small as 10(-4) cm(-1), are well reproduced by our calculations at sixth order.     

毛细管电泳在完整哺乳动物细胞分析中的应用

作为人体形态结构、生理功能和生长发育的基本单位,细胞的结构功能及行为分析具有重要的研究价值。毛细管电泳作为日渐成熟的微量分析技术在细胞分析及应用方面已取得显著进展。本文综述了毛细管电泳在完整哺乳动物细胞分析中的应用,包括群体细胞分析和完整单细胞分析。所述内容涉及血红细胞、公猪精子、人宫颈癌细胞、人神经母细胞瘤细胞、人结直肠腺癌细胞、人慢性髓系白血病细胞以及鼠小脑颗粒细胞。总结了完整哺乳动物细胞分析的毛细管电泳方法和条件,归纳分析了完整细胞分析中存在的细胞破碎、聚集、沉降、吸附及电泳异质性等关键问题及解决方法。对毛细管电泳在细胞分析方面未来的应用方向进行了展望。综述文献49篇。