Rheological characteristics of tamarind (Tamarindus indica L.) juice concentrates

The steady-shear and small-amplitude oscillatory rheological properties of tamarind (Tamarindus indica L.) juice concentrate (TJC) were studied in the temperature range of 10-90 °C using a controlled-stress rheometer. Under steady-shear deformation tests, shear stress-shear rate data were adequately fitted to the Herschel-Bulkley and Casson model at lower (10-30 °C) and higher (50−90 °C) temperature range, respectively. The Carreau model was applied to describe the shear-thinning behaviour of the concentrate, and the model parameters estimated empirically showed temperature dependence. Oscillatory shear data of TJC revealed predominating viscous behaviour (G″>G′) at lower frequency range while the elastic modulus predominating over the viscous one (G′>G″) at higher frequency range. The Cox-Merz rule that relates steady shear and dynamic material functions was tested and not followed by most of the temperatures. The specific heat of TJC increased with temperature and the glass transition temperature of the product was found to be −70.74 °C.     

布拉维法则和剪式合成法与高品级金刚石

讨论两种与高品级金刚石有关指导思想。似乎是些纯基础理论的内容,但绝非如此,它是指导我们一些基本思路的方法。     

阳离子疏水缔合聚丙烯酰胺的合成及性能

以环氧氯丙烷、丙烯酰胺(AM)及N,N-二甲基十八烷基叔胺为原料,制备了二甲基十八烷基(2-羟基-3-丙烯酰胺丙基)氯化铵(DMOHAC)阳离子表面活性单体,利用红外光谱及核磁共振氢谱方法对其结构进行了表征,并将DMOHAC与AM通过胶束共聚反应制备了阳离子疏水缔合聚丙烯酰胺P(DMOHAC/AM),通过红外光谱对聚合物的结构进行了表征,并利用表观黏度法考察了DMOHAC用量、疏水嵌段长度及疏水碳链长度不同的表面活性剂对P(DMOHAC/AM)溶液缔合性能的影响.结果表明,P(DMOHAC/AM)聚合物与阴离子表面活性剂在疏水缔合、静电吸引及氢键三重作用下能显著提高聚合物溶液的缔合性能,且阴离子表面活性剂与P(DMOHAC/AM)聚合物之间的缔合作用随表面活性剂烷基碳链长度的增加而增强.     

几种常用酸碱盐对明胶透明度和黏度的影响

研究了明胶提取过程中 ,几种常用酸碱盐对明胶透明度和黏度的影响。结果表明 :柠檬酸、硫酸和氢氧化钠用量的增加 ,明胶的透明度先降到最低点而后上升 ;其它材料用量增加 ,明胶的透明度下降。明胶的黏度随氢氧化钠用量的增加而下降 ,随氧化镁用量的增加而升高 ,碳酸钙和氢氧化钙用量的变化对明胶黏度影响不大。而酸用量对明胶黏度的影响比较复杂 ,其变化趋势与明胶的等电点有关。在等电点之前 ,黏度随着硫酸用量的增加而升高 ,随着柠檬酸用量的增加先降而后升 ;在等电点之后 ,黏度随着硫酸和柠檬酸用量的增加而下降     

粮油食品中真菌毒素的LC-MS法检测

粮油食品中常见的真菌毒素有:黄曲霉毒素、赭(棕)曲霉毒素、展青霉毒素、玉米赤霉烯酮、串珠镰刀菌毒素及脱氧雪腐镰刀菌烯醇等,因含量较低,用常规方法检测不出来。用LC-MS检测,灵敏度高、前处理比较简单,结果准确可靠,在检测食品中真菌毒素上前景广阔。     

紫苏精油与环糊精包结物的制备与光谱研究

利用紫外可见光谱法(UV-Vis)测定了β-CD及其衍生物与VOP作用的包结比和包结常数;测定了包结过程在30～45℃范围内的热力学参数△G、△H、△S;研究了包结物的抗光解作用;以饱和水溶液法制备固体包结物,用红外吸收光谱进行包结物鉴定。实验表明,β-CD及其衍生物与紫苏挥发油的包结比均为1∶1,包结能力顺序为HP-β-CD>HE-β-CD>M-β-CD>β-CD,包结反应是一个放热过程,以焓变为主,符合熵焓补偿效应,范德华是主要的驱动力。     

植物蛋白肉产品品质评价及过敏原分析

为考察不同类别、不同品牌植物蛋白肉的品质,对市售18种植物蛋白肉产品进行感官评价及仪器检测,并对感官评价结果与仪器分析结果进行关联性分析,进一步探讨了过敏原的存在风险.通过外观、风味、口感等方面的指标可对植物蛋白鸡块、牛肉饼、肉馅品类有效评价产品像真性.全质构分析(TPA)参数中的咀嚼性和剪切力可以有效地评价感官指标,...     

A viscometric study of the interaction of polybutadienyllithium with N,N,N′,N′-tetramethylethylenediamine in benzene

Moderately concentrated solutions of polystyryllithium in benzene were prepared under high vacuum conditions in an Ubbelohde viscometer and the active chain ends were ‘capped’ with a few molecules of butadiene. The flow times of these solutions were determined before and after the addition of small aliquots of N,N,N′,N′-tetramethylethylenediamine (TMEDA) and finally following protonation of the carbanions with a trace of alcohol. The addition of the TMEDA caused a decrease in the viscosity that was slightly greater than that predicted on the basis that two molecules of TMEDA cause the disaggregation of a dimeric polybutadienyllithium associate.     

Change in the molecular weight distribution of poly(ethylene oxide) caused by the complexation with poly(acrylic acid)

The complexation between poly(ethylene oxide) (PEO) and poly(acrylic acid) (PAA) was made by using double the molar quantity of either polymer component at pH 2 where the resulting complex completely precipitates. After the removal of the precipitate, PEO or PAA remaining in the supernatant was subjected to gel permeation chromatography to investigate the change in the molecular weight distribution (MWD) caused by the complexation. No remarkable difference is observed in the MWD curves for PEO[1] (M_w=1.37 × 10⁴) before and after the complexation with PAA[1] (M_w=1.10 × 10³) and PAA[2] (M_w=4.16 × 10⁵). However, the MWD curves of PEO[2] (M_w=1.26 × 10⁵) and PAA[2] become shortened and shift to the low molecular weight side after the complexation with PAA[1] or [2] and PEO[2], respectively. This tendency is enhanced by increasing the complexation temperature. From these results, it is indicated that the complexation between PEO and PAA deals with an equilibrium reaction, and the equilibrium constant is dependent on the chain length of both polymer components and also on the complexation temperature.     

基于动态阈值启发式图搜索的SLAM算法

针对当前多数SLAM数据关联算法存在不能在线修正的问题,提出一种使用动态阈值的启发式图搜索数据关联算法.该方法使用回溯机制实现对错误数据的修正,在搜索过程中使用动态阈值进行门限过滤,减少可能的数据关联的数目,在不降低数据关联正确率的情况下,提高数据关联效率.仿真实验结果表明,该算法可有效地降低运算时间.