C/SiC复合材料应力氧化失效机理

研究了干氧和湿氧两种气氛、疲劳和蠕变两种应力下C/SiC复合材料在1300℃的应力氧化行为. 试验结果和断口形貌SEM分析表明: C/SiC复合材料在疲劳应力下比在蠕变应力下具有更强的抗氧化能力和更长的持续时间; 干氧环境中的蠕变试样以C纤维氧化失效为主; 水蒸气的存在加剧了SiC基体的氧化, 并且使受蠕变应力的C/SiC复合材料以SiC基体氧化失效为主.     

Web服务测试研究

Web服务技术为软件测试研究带来了新的挑战。Web服务测试需要能够适应面向服务的新的分布式计算体系架构。为保证服务的质量，Web服务需要从多个层次进行验证与确认，包括基础设施、单元服务、集成服务等；测试需涵盖服务的功能、性能、可靠性、安全等各个方面。本文从web服务体系架构和应用模式出发，讨论了Web服务测试的主要问题。文章分析当前相关研究的现状，并归纳总结了SOAP协议验证、WSDL语言扩展、基于模型的服务集成验证、和测试构架等主要研究成果。本文最后讨论了当前存在的主要问题及进一步的研究方向。     

基于免疫克隆选择的块匹配运动估计

运动估计是视频压缩编码中的关键技术.从运动矢量的特点出发,采用搜索点预测、Gray码编码以及有效的迭代终止准则等策略,提出了基于免疫克隆选择的块匹配运动估计.该方法将块匹配运动估计问题的性质与免疫克隆选择算法所具有的全局搜索特性、解的多样性和不易早熟的特点相融合,在能够获得接近全搜索方法所得到的平均峰值信噪比的前提下,使得平均搜索点数大为降低.仿真实验结果表明,在大多数序列上,该算法都比已有的快速搜索算法具有更高的性能和更少的平均搜索点数.同时,该算法适用面广,对大运动和小运动序列都能得到较好的效果.     

成纤维细胞和血小板在多壁碳纳米管上粘附性

使用化学气相沉积(CVD)的方法在碳纸基底上制备了多壁碳纳米管(MWCNTs),并研究了L929小鼠成纤维细胞在多壁碳纳米管和碳纸对照组上的粘附及增殖等生长行为,以及各种血液蛋白吸附于这两种材料表面后对人皮肤成纤维细胞粘附产生的影响,同时对比了这两种材料的血小板粘附情况.结果表明:种植在多壁碳纳米管上的成纤维细胞生长明显比碳纸上的旺盛,细胞浓度从第1天的12.5×10~5/mL明显增加到第7天的4.1×10~5/mL,多壁碳纳米管对细胞无毒性反应.预吸附白蛋白、纤维蛋白原、免疫球蛋白对细胞粘附量有促进作用,并且多壁碳纳米管的血小板粘附率低于碳纸.这些结果证明多壁碳纳米管具有良好的组织相容性和一定的血液相容性.     

Comparative study of isoflavones in wild and cultivated soybeans as well as bean products by high-performance liquid chromatography coupled with mass spectrometry and chemometric techniques

A high-performance liquid chromatography method coupled with mass spectrometry and chemometric analysis has been developed for the quality evaluation of wild and cultivated soybean as well as bean products. Fifteen isoflavones were qualified by LC–MS and quantified by HPLC. The assay results demonstrated that the type of isoflavones was quite similar between cultivated and wild soybean, and 6″-O-malonylglucosides were the main ingredients in soybean, while glucosides and aglycones were abundant in bean products. Moreover, the unsupervised chemometric methods including principal component analysis (PCA) and cluster analysis revealed that different species, geographic locations, and the processing methods have great influences on the chemical properties of soybean and bean products. In conclusion, HPLC coupled with chemometric techniques would be a very flexible and reliable method for dietary selection of soybean and bean products.     

SIMULINK在水轮机调节系统仿真中的应用

在小波动范围内,建立了水轮机调节系统各部分的数学模型,采用SIMULINK仿真软件对水轮机调节系统在１％频率扰动和机组突减30%负荷情况下的动态特性进行了仿真分析。通过仿真,整定了水轮机调节系统空载频率扰动过程中,暂态转差系数bt=0.4,暂态反馈时间常数Td=2.95和负荷扰动过程中bt=0.5,Td=2.95的最佳调节参数,获得水轮机调节系统良好的快速性和稳定性。结果表明,利用SIMULINK仿真软件对水轮机调节系统进行仿真研究,方便、灵活。     

广西部分食品中防腐剂检测结果分析

目的了解广西部分食品中防腐剂使用情况。方法从8类场所随机抽取14类食品样品,按照相应标准检测7种食品防腐剂,对检测结果进行分析。结果共检测2386批次食品样品,防腐剂不合格样品9批次,不合格率为0.38%;脱氢乙酸及其钠盐、山梨酸及其钾盐检出率较高,分别为35.07%、21.17%,山梨酸及其钾盐不合格率最高,为0.21%。山梨酸及其钾盐、苯甲酸及其钠盐、乙二胺四乙酸二钠等3种防腐剂在预包装食品中的检出率高于散装食品,脱氢乙酸及其钠盐和丙酸及其钠盐、钙盐在散装食品中检出率高于预包装食品。蔬菜制品复合使用防腐剂样品占其抽检样品量的58.82%,其次是焙烤食品,占比为32.37%。结论广西企业生产的部分食品中防腐剂使用基本符合GB2760-2014《食品安全国家标准食品添加剂使用标准》要求,少量食品存在超范围超限量添加防腐剂问题,部分食品复合使用两种以上防腐剂。     

Formation and dynamic interfacial adsorption of glycinin/chitosan soluble complex at acidic pH: Relationship to mixed emulsion stability

The formation and interfacial adsorption of glycinin/chitosan (CS) soluble complex were investigated at acidic pH. The stability of the mixed emulsion stabilized by the complex was also evaluated at pH 4.5. Turbidimetric analysis, isothermal titration calorimetry (ITC) and dynamic light scattering were used to characterize the dynamic formation of the complex. The results showed that soluble complexes were formed mainly at pHs between 4.0 and 6.0, depending on CS/Glycinin mixing ratio. At pH 4.5, soluble complex was formed and saturated at mixing ratio = 0.1, showing a maximum size distribution at 164.2 nm. We found that the glycinin/CS soluble complex showed improved interfacial adsorption than glycinin at pH 4.5. In detail, dynamic interfacial adsorption data showed the coefficient of diffusion (K_diff), unfolding (K₁) and rearrangement (K₂) for soluble complex (K_diff, K₁ and K₂: 0.58 mNm⁻¹ s^−0.5, 2.23 E−4 s⁻¹ and 5.78 E−4 s⁻¹) were higher than those of the glycinin (K_diff, K₁ and K₂: 0.32 mNm⁻¹ s^−0.5, 1.72 E−4 s⁻¹ and 4.63 E−4 s⁻¹). The droplet size and confocal observation of the mixed emulsion fabricated with glycinin/CS soluble complex displayed improved stability at mixing ratios of 0.1 to/and 0.2, suggesting the synergistic effect of the two molecules. We concluded that interfacial and emulsifying properties of glycinin could be improved by formation of glycinin/CS soluble complex at acidic pH.     

Active sites modulation with Runge–Gross theorem: CO2 capture by porphyrinic metal–organic frameworks at excited states

Traditionally chemical modifications altering molecular skeletons (MSs) were the only solution to modulate material active sites at ground states. According to Runge–Gross theorem, the MS and the adjoint electron-configuration (MS-AEC) can be tuned at excited states (ESs), even without chemical modifications. A porphyrinic metal–organic framework PCN-222 and its metalloporphyrin homologs are used for adsorptive carbon capture both at ground states and with photoexcitation (350–780 nm). Instead of passive photothermal effects, the carbon capture performances of all the adsorbents get promotions. The dominant first ESs with long lifetimes meet the time-scale of molecular adsorption equilibrium, meanwhile tune the MS-AEC of the porphyrin ligands to generate new active sites with much more negative electrostatic-potentials, of which the distribution gradient is crucial for inducing CO₂ and can be further modulated by the central-coordinated metal cations at ground and excited states. This work demonstrates the availability of static ESs and possibility of nonchemical modifications.