爆炸条件下溶菌酶反应产物的基质辅助激光解吸-飞行时间质谱分析

以爆炸条件下溶菌酶的反应产物为研究对象,运用基质辅助激光解吸-飞行时间质谱的方法研究其反应产物与不同炸药的反应特征性.结果显示,雷管的使用不会对溶菌酶有影响,而在有爆炸物爆炸的条件下,除了正常溶菌酶酶解多肽信号外,一些[MH+17]+,[MH+18]+,[MH+28]+,[MH+32]+和[MH+44]+的加合峰信号也能被检测到.这可能是在炸药爆炸过程中产生的一些活性小分子(如NH3,H2O,CO/N2,O2,CO2)与溶菌酶发生反应得到的反应产物.不同炸药生成的活性小分子能够分别与溶菌酶的某些反应位点反应生成特征性的反应产物,有利于这些炸药的分析与检测.     

Structure of the calcium pyrophosphate monohydrate phase (Ca2P2O7·H2O): towards understanding the dehydration process in calcium pyrophosphate hydrates

Calcium pyrophosphate hydrate (CPP, Ca₂P₂O₇·nH₂O) and calcium orthophosphate compounds (including apatite, octacalcium phosphate etc.) are among the most prevalent pathological calcifications in joints. Even though only two dihydrated forms of CPP (CPPD) have been detected in vivo (monoclinic and triclinic CPPD), investigations of other hydrated forms such as tetrahydrated or amorphous CPP are relevant to a further understanding of the physicochemistry of those phases of biological interest. The synthesis of single crystals of calcium pyrophosphate monohydrate (CPPM; Ca₂P₂O₇·H₂O) by diffusion in silica gel at ambient temperature and the structural analysis of this phase are reported in this paper. Complementarily, data from synchrotron X‐ray diffraction on a CPPM powder sample have been fitted to the crystal parameters. Finally, the relationship between the resolved structure for the CPPM phase and the structure of the tetrahydrated calcium pyrophosphate β phase (CPPT‐β) is discussed.     

Effect of calcination temperature on structure and characteristics of calcium oxide powder derived from marine shell waste

Marine fishery wastes such as bivalve shells, crab shells and cuttlebone are rich in calcium. Calcium carbonate derived from these materials can be transformed into calcium oxide by calcination, which is used in a wide variety of applications (e.g., biomaterials for bone and teeth implants and drugs). In this study we analyze the effects of calcination temperatures (550 °C, 700 °C and 900 °C) on characteristics and elemental composition of calcium oxide derived from shells of four marine species collected in Thailand: oyster (Saccostrea cucullata), green mussel (Perna viridis), blue swimming crab (Portunus pelagicus), and cuttlefish (Sepia brevimana). The XRD patterns indicated the complete transformation of calcium carbonate into calcium oxide, observed by the changes of diffraction angles at 900 °C for all calcined samples, except cuttlebone, which was calcined successfully at 700 °C. Likewise, the FT-IR results revealed changes of functional groups at the same calcination temperatures. In addition, ICP-OES showed the effects of calcination temperature on elemental contents: major elements (Ca, P and K) increased in all samples, and some minor elements increased in blue swimming crab shell (Zn and Cu) and oyster shell (Fe) as a result of increasing the calcination temperature. This study demonstrates the optimum calcination temperature of calcium oxide production from four types of marine wastes that might be benefit for the chemical compound production industry.     

Dielectric properties and study of AC electrical conduction mechanisms by non-overlapping small polaron tunneling model in Bis(4-acetylanilinium) tetrachlorocuprate(II) compound

In the present work, the synthesis and characterization of the Bis(4-acetylanilinium) tetrachlorocuprate(II) compound are presented. The structure of this compound is analyzed by X-ray diffraction which confirms the formation of single phase and is in good agreement the literature. Indeed, the Thermo gravimetric Analysis (TGA) shows that the decomposition of the compound is observed in the range of 420–520 K. However, the differential thermal analysis (DTA) indicates the presence of a phase transition at T=363 k. Furthermore, the dielectric properties and AC conductivity were studied over a temperature range (338–413 K) and frequency range (200 Hz–5 MHz) using complex impedance spectroscopy. Dielectric measurements confirmed such thermal analyses by exhibiting the presence of an anomaly in the temperature range of 358–373 K. The complex impedance plots are analyzed by an electrical equivalent circuit consisting of resistance, constant phase element (CPE) and capacitance. The activation energy values of two distinct regions are obtained from log σT vs 1000/T plot and are found to be E=1.27 eV (T<363 K) and E=1.09 eV (363 K<T).The frequency dependence of ac conductivity, σ_ac, has been analyzed by Jonscher's universal power law σ(ω)=σ_dc+Aω^s. The value of s is to be temperature-dependent, which has a tendency to increase with temperature and the non-overlapping small polaron tunneling (NSPT) model is the most applicable conduction mechanism in the title compound.     

Carbon Nanotube Reinforced Titanium Metal Matrix Composites Prepared by Powder Metallurgy—A Review

Titanium-based metal composites (TMCs) are showing great potential to replace existing traditional materials in aerospace, automotive, and other high temperature engineering applications. This is due to their excellent mechanical, thermal, and physical properties and improved strength to weight ratio. Weight savings in the aerospace industry results in higher efficiency. Carbon nanotubes (CNTs), because of their low density and high Young's modulus, are considered to be an excellent reinforcement for metal matrix composites (MMCs). In the last 20 years extensive research has been carried out to investigate the combination of carbon nanotubes with aluminum, nickel, copper, magnesium, and other metal matrices. The production techniques such as mechanical alloying through powder metallurgy routes and their effects on the mechanical properties of CNT reinforced TMCs are reviewed in this article. The role of the volume fraction of carbon nanotubes and their dispersion into the metal matrix are highlighted. Governing equations to predict the mechanical and tribological properties of CNT reinforced titanium matrix composites are deduced. With the help of this initial prediction of properties, the optimal processing parameters can be optimized. Successful development of CNT reinforced TMCs would result in better wear and mechanical behavior and enhance their ability to withstand high temperature and structural loading environments.     

超高效液相色谱-串联质谱快速检测精米、玉米与土豆样品中噻呋酰胺残留

采用分散固相萃取(QuEChERS)为样品前处理方法,建立了超高效液相色谱-串联质谱(UPLCMS/MS)快速检测精米、玉米和土豆中噻呋酰胺残留的分析方法。样品经乙腈提取,PSA净化,超高效液相色谱分离,电喷雾电离、负离子扫描,三重四极杆串联质谱以多反应监测扫描方式进行检测,基质匹配标准品外标法进行定量分析。结果显示,噻呋酰胺在1.0~1 000μg·L-1范围内呈良好线性(r2=0.999 0)。在0.01~1.0 mg·kg-1加标水平范围内,噻呋酰胺在精米、玉米和土豆中的平均回收率为89.1%~109.3%,相对标准偏差为3.5%~8.7%,检出限(LOD)为0.009~0.015μg·kg-1,定量下限(LOQ)为0.032~0.049μg·kg-1。该方法简便、快速、准确,可用于精米、玉米和土豆中噻呋酰胺农药残留的确证检测。     

C.I.颜料红177中间体的制备工艺改进

本文较为系统地研究了铜粉催化剂加入方式对C.I.颜料红177中间体4,4'-二氨基-1,1'-二蒽醌-3,3'-二磺酸(DAS)合成过程中的乌尔曼偶联反应速率的影响规律。 研究结果表明,在55 ℃较佳反应温度下,先加入与溴氨酸钠质量比为2:5的铜粉,反应一段时间后再加入与溴氨酸钠的质量比为1:5的铜粉,与一次性加入与溴氨酸钠的质量比为3:5的铜粉相比较,综合反应时间可节省2~3 h。 另外,对于DAS中混有的铜盐,采取在制备过程中加入柠檬酸的方法予以去除,此举可提高DAS的纯度。 当铜粉与柠檬酸的质量比为6:1时,可使DAS中铜盐的含量小于0.001%。 此外还探究了蒸馏后滤液的剩余量对DAS收率的影响,结果表明,滤液的剩余量在20 mL时,DAS的收率在95%以上。 基于本文的研究结果提出,欲进一步提高该反应的收率,需要寻找更高效的催化剂。     

用于荧光光谱测定的微量固体粉末样品制样优化*

为满足微量固体粉末荧光检测要求,采用薄层制样法,改变黏结剂种类、黏结剂的用量、涂层厚度以及后处理方法来进行其制样工艺优化。 结果表明:以聚乙烯醇做黏结剂、1∶5的固液比、在50 ℃烘干30 min、涂片次数3层的薄层制样优化工艺可满足荧光固体测样的要求。采用t检验比较固体样品池装样和薄层制样法的荧光检测结果发现两者无显著性差异,薄层制样优化工艺的需样量较样品池减少90%。     

Multiobjective Optimization of Fabrication Parameters of Jute Fiber/Polyester Composites with Egg Shell Powder and Nanoclay Filler

In the present study, a model is presented to optimize the fabrication parameters of natural fiber reinforced polyester matrix composites with dual fillers. In particular, jute fiber mat was chosen as reinforcement and eggshell powder (ESP) and montmorillonite nanoclay (NC) were selected as fillers. The weight per square meter (GSM) of the fiber, the weight percentage of ESP and NC have been chosen as independent variables and the influence of these variables on tensile, flexural and impact strength of the composite has been inspected. The permutations of the different combinations of factors are intended to accomplish higher interfacial strength with the lowest possible number of tested specimens. The experiments were designed by the Taguchi strategy and a novel multi-objective optimization technique named COPRAS (COmplex PRoportional ASsessment of alternatives) was used to determine the optimal parameter combinations. Affirmation tests were performed with the optimal parameter settings and the mechanical properties were evaluated and compared. Experimental results show that fiber GSM and eggshell powder content are significant variables that improve mechanical strength, while the nanoclay appears less important.     

粉末微波滤波器的制备和特性

利用通电导线的电磁感应和铜粉的趋肤效应,试制了在超导量子计算实验系统中使用的粉末微波滤波器.滤波器的频率响应随频率升高而平缓下降,在1GHz左右衰减至-80dB.我们分析了滤波器的原理,并通过改变参数对滤波器性能的变化进行了详细的研究.