金莲花活性成分研究

用柱层析等色谱分离手段从金莲花中得到三个纯化合物,通过现代波谱技术分别鉴定为原金莲酸、牡荆甙和荭草甙.经对上述化合物和所提取的总黄酮样品进行抑菌、抗病毒活性研究.结果表明,总黄酮、牡荆甙和荭草甙对金黄色葡萄球菌和表皮葡萄球菌有很好的抑制效果,并对副流感病毒有强的抑制作用.     

On the molecular origin of the sensitivity to impact of cyclic nitramines

Nitramine explosives can combine relative insensitivity to initiation and great energy content. In this work, based on a previous approach developed for nitroaromatic explosives, we propose four mathematical models to correlate impact sensitivity, given by the h₅₀ value, to molecular charge properties. Fourteen cyclic nitramines were studied using Density Functional Theory (DFT). Six molecules of the set have measured h₅₀ values, which were used to evaluate the sensitivity models. Converged DFT charge densities of the molecules were partitioned and analyzed according to the distributed multipole analysis (DMA) atom-centered method. The sensitivity models were based on the DMA electric multipole values. The electron withdrawing role of the nitro group and the strong polarization of the charges of the nitrogen atom in the amine group were clearly identified. The influence of the electronic properties on the sensitivity of the explosives was characterized by including in the sensitivity models the charge values of the nitro or the nitramine groups and electron delocalization, the latter quantified by the DMA quadrupole values of the ring atoms. Inclusion of electron delocalization effects can improve the prediction of h₅₀ values for two out of the five strained-ring nitramines in the set. The charge values of the nitramine groups are the most important molecular property affecting the impact sensitivity. The h₅₀ values of eight nitramine explosives of the set not available experimentally were computed.     

Study of the fractional and fatty-acid compositions of the phospholipids ofPsoralea seeds

Summary The fractional and fatty-acid compositions of the phospholipids of Psoralea seeds have been studied for the first time. It has been established that the total phospholipids consist of phosphatidylcholines, phosphatidylethanolamines, phosphatidylinositols, N-acyl-PEs, N-acyllyso-PEs, lysophosphatidylcholines, and, possibly, phosphatidylglycerols, and also of two unidentified phospholipids.Institute of the Chemistry of Plant Substances, Academy of Sciences of the Uzbek SSR, Tashkent. Translated from Khimiya Prirodnykh Soedinenii, No. 1, pp. 12–14, January–February, 1979.     

Study of triplet kinetic of thermal decomposition reaction and sensitivity to impact and electrostatic discharge of HMX polymorphs

Journal of Thermal Analysis and Calorimetry - The polymorphs of HMX explosive show the different sensitivities to heat, friction, impact, shock, electrostatic charge, etc. Knowledge and...     

Theoretical investigation on the impact sensitivity of tetrazole derivatives and their metal salts

The relative orders of impact sensitivity of tetrazole derivatives and their metal salts are investigated by examining the activation energy for forming azide in the process of thermal decomposition based on PM3-SCF-MO calculations. It is found that there is a parallel relationship between the activation energy and the sensitivity and a good linear relationship between the experimental impact sensitivity of metal salts of tetrazole and the reaction activation energy. It is shown that treating the metal salts of the tetrazole derivatives as the metal derivatives of tetrazole is meaningful.     

Study of the structure and curing of thiourethane elastomers based on oligomer compositions

Data on the structure formation of thiourethane elastomers based on oligo(diene diols) and polysulfide oligomers are generalized. The curing of oligo(diene diols) by polyfunctional isocyanates in the presence of liquid thiokols and glycerol is characterized by the formation of highly branched molecules already at the early stages of structure formation. This feature predetermines the microheterogeneous character of the process and the appearance of the gel fraction at low conversions of functional groups. The maximum values of the curing rate and crosslink density are achieved at NCO: (OH + SH) = 1.     

Stress accumulation in Ni-rich layered oxide cathodes:Origin,impact,and resolution

LiNi_xCo_yMn_zO₂(NCM,x+y+z=1)is one of the most promising cathode candidates for high energy density lithium-ion batteries(LIBs).Due to the potential in enhancing energy density and cyclic life of LIBs,Ni-rich layered NCM(NCM,x≥0.6)have garnered significant research attention.However,improved specific capacity lead to severer expansion and shrinkage of layered lattice,accelerating the stress generation and accumulation even microcracks formation in NCM materials.The microcracks can promote the electrolyte permeation and decomposition,which can consequently reduce cyclic stabilities.Therefore,it is significant to provide an in-depth insight into the origin and impacts of stress accumulation,and the available modification strategies for the future development of NCM materials.In this review,we will first summarize the origin of stress accumulation in NCM materials.Next,we discuss the impact of stress accumulation.The electrolyte permeation along microcracks can enhance the extent of side reaction at the interface,trigger phase transformation and consequential capacity fading.To cushion the impact of stress accumulation,we will review five main strategies.Finally,concise perspectives to reduce stress accumulation and enhance particle strength in further works will be presented.     

裂褶菌茵丝体各提取成份免疫生物活性研究

研究裂褶菌茵丝体的乙醇脱脂浸膏、石油醚萃取成份、乙酸乙酯萃取成缮份及糖蛋白部份对小鼠淋巴细胞的增殖作用.结果表明石油醚及糖蛋白部份对小鼠淋巴细胞的增殖具有明显的免疫抑制作用,而乙酸乙酯与乙醇部份既有免疫抑制,又有免疫增强作用.     

Evaluation of the renal calculi compositions

Thermal analysis and infrared (IR) spectroscopy are modern physical–chemical methods suitable for the investigation of the kidney stones composition. The applications of these methods in our work were anticipated by performing the standard thermal analysis and standard infrared spectra on pure compounds: oxalates, phosphate, carbonate, and uric acid. This work reveals a logical algorithm for correlating the experimental data regarding urolithiasis types and compositions by thermal analysis methods, Fourier Transform Infrared (FT-IR) spectroscopy, and second derivative FT-IR spectra. The limits and performance of each analysis method have been highlighted, and by correlating the results of both methods we have obtained comprehensive information for the identification and/or determination of the main components as well as of organic and/or inert impurities in calculi composition. The data regarding the urinary calculi composition are important for the clinical guideline in the prophilaxy and methaphylaxy of urolithiasis.     

Study of an alternative material to manufacture layered hydraulic hoses

Hydraulic hoses are components of umbilical cables and others subsea equipments. They are manufactured from thermoplastic polymers and are susceptible to collapse under external pressure, which can cause plastic strains around the circumference, leading to failure under internal pressure (bursting). This work studies an alternative hydraulic hose liner capable of support such load history, even after long time exposure to the hydraulic fluid. It is based on the comparison between the material currently used (Polyamide 11) and a fluorinated elastomer, Viton^®. Mechanical characterization, ageing tests as well as nonlinear finite elements simulations were accomplished to issue both performances. The results obtained showed that Viton^® liners are mechanically more suitable than Polyamide 11 liners to such hoses. The ageing tests showed compatibility between Viton^® and the hydraulic fluid. Considering that the external aramid layer is responsible to withstand the internal pressure in both cases, Viton^® can successfully replace Polyamide 11 for this application as well as others involving layered hoses under combined internal and external pressure.     

Study of physical and mechanical properties and combustibility of filled acrylate compositions

Compositions based on cross-linked acrylate copolymers and bentonites were obtained. Physical-mechanical and absorption characteristics of bentonite-polymeric composite materials were studied. The effect of a filling agent on the final product properties was demonstrated. The possibility of using these compositions for creating materials with reduced combustibility was shown.     

Thermodynamics of the mixing of lignincontaining compositions

The thermodynamic mixing parameters in the composition nitrolignin-hydrolyzed nitron have been determined and it has been shown that the system is thermodynamically stable over the whole range of compositions.Institute of the Chemistry of Plant Substances, Academy of Sciences of the Republic of Uzbekistan, Tashkent, fax (3712) 40 64 75. Translated from Khimiya Prirodnykh Soedinenii, No. 6, pp. 874–876, November–December, 1997.     

TATB及其衍生物的撞击感度与C-NO2键级的关系

对TATB及其系列衍生物进行了半经验分子轨道PM3和AM1计算，求得全优化几何构型和电子结构．结果发现各化合物分子中C-NO2键的Wiberg键级(WCN)均小于其他C—N或C—C键的键级．实验撞击感度h50%与WCN计算结果之间分别呈三阶成二阶多项式关系，相关系数r≥0．92．当WCN＜0．90时，该值对撞击感度影响甚微，表明属高感度炸药；而当WCN＞0．90时，撞击感度与分子中最小的G—NO2键级WCN呈显的线性关系，WCN增大，撞击感度线性递减，符合判别感度相对大小的“最小键级原理”．     

Band gaps and the possible effect on impact sensitivity for some nitro aromatic explosive materials

The first principle density functional theory method SIESTA has been used to compute the band gap of several polynitroaromatic explosives, such as TATB, DATB, TNT, and picric acid. In these systems, the weakest bond is the one between an NO₂ group and the aromatic ring. The bond dissociation energy (BDE) alone cannot predicate the relative sensitivity to impact of these four systems correctly. It was found that their relative impact sensitivity could be explained by considering the BDE and the band gap value of the crystal state together. © 2009 Wiley Periodicals, Inc. Int J Quantum Chem, 2009     

First-principles band gap criterion for impact sensitivity of energetic crystals: a review

In this article, we review some recent studies in predicting impact sensitivity for different classes of energetic crystals based on first-principles band gap. Based on these investigations on metal azides, a first-principles band gap criterion is founded to measure impact sensitivity for a series of energetic crystals. For energetic crystals with similar structure or with similar thermal decomposition mechanism, the smaller the band gap is, the easier the electron transfers from the valence band to the conduction band, and the more they becomes decomposed and exploded. Applications of this criterion on other series of energetic crystals show that the first-principles band gap criterion is applicable to different series of energetic crystals with similar structure or with similar thermal decomposition mechanism. This criterion may be useful for molecular design of high-energy density materials.