糯小麦淀粉分子—碘包合物的研究

本文通过测定糯小麦淀粉、糯玉米淀粉和谷物淀粉与碘结合后的吸收光谱,发现直链淀粉分子和支链淀粉分子在与碘分子形成包合物时存在结合速率(结合顺序)的差异。即直链淀粉首先与碘结合,只有当碘液的添加量足够大,与直链淀粉充分结合后仍剩余有一定量时,支链淀粉才与碘结合。同时,本文测定了几种糯小麦淀粉的直链淀粉分子含量,发现不同文献测量值之间的差异是计算基准不同造成的。

氡子体粒径分布测量实验比对研究

为评估氡子体粒径分布测量的准确性和可靠性,本文研究了粒径扫描法、低压撞击器法和丝网扩散法的3种氡子体活度粒径分布测量方法。依据气溶胶结合理论,以粒径扫描间接测量法作为气溶胶活度粒径参照,在氡室环境和室内环境开展了低压撞击器法和丝网扩散组法测量氡子体活度粒径比对研究。研究表明:撞击器法、丝网扩散组法2种直接测量方法测得的活度几何粒径均值与间接测量法一致性较好;撞击器法在氡室内测量粒径略微偏低,在室内低活度浓度环境下具有很好的一致性;丝网扩散组在粒径300 nm以下时具有很好的一致性,在粒径大于500 nm时误差较大不再适用;在室内低活度环境下,丝网扩散组法受限于测量灵敏度,测量结果的不确定性显著增大。3种方法各有优缺点,适用于不同环境的氡子体粒径分布测量。

Influence of strain rate on microstructure and formability of AZ31B magnesium alloy sheets

The effects of strain rate on microstructure and formability of AZ31B magnesium alloy sheets were investigated through uniaxial tensile tests and hemispherical punch tests with strain rates of 10^-4, 10^-3, 10^-2, 10^-1 s^-1 at 200℃. The results show that the volume fraction of dynamic recrystallization grains increases and the original grains are gradually replaced by recrystallization grains with the strain rate decreasing. A larger elongation and a smaller r-value are obtained at a lower strain rate, moreover the erichsen values become larger with the strain rate reducing, so the formability improves. This problem arises in part from the enhanced softening and the coordination of recrystallization grains during deformation.

Effects of retrogression heating rate on microstructures and mechanical properties of aluminum alloy 7050

The effects of the retrogression heating rate(340℃/min,57℃/min,4.3℃/min)on the microstructures and mechanical properties of aluminum alloy 7050 were investigated by means of hardness measurement,tensile properties testing,differential scanning calorimetry(DSC)and transmission electron microscopy(TEM).The results show that the retrogression heating rate significantly affects the microstructures and mechanical properties of the alloys treated by retrogression and re-aging(RRA)process, and it is found that the medium rate(57℃/min)leads to the highest mechanical properties.The strengthening phases in the matrix are mainly the fine dispersed η′precipitates and GP zones,and the grain boundary precipitates are coarse and discontinuous η phases.

Rheological catastrophic model for soft clays

A brief review of the former studies on the mechanisms of soil rheology and microstructure is presented. Then a microstructure model and a set of rheological constitutive relations for sott clays, which describe how the rheological consolidation settlement develops, are established in the framework of the catastrophe theory. The validity of this model is verified by a series of rheological consolidation experiments with different loading rates. The experimental data show that creep deformation can be clearly observed in these tests, and the consolidation settlement is loading rate dependent. The characteristics of the deformation can be explained and reproduced successfully using the model. It can be concluded that only the biggest set of voids would collapse for one load increment. Parameters in the model, k and η, are gained by curve fitting. With only two free parameters, good fits of the data are achieved.

动平衡毛细管电泳的研究进展

动平衡毛细管电泳(KCE)是一种既能测定配受体间相互作用热力学参数、还可获得配受体间动力学参数的新方法。本文对动平衡毛细管电泳的发展历史、作用模式和原理,以及动平衡毛细管电泳目前存在的一些问题进行了评述。

黄芩素、槲皮素、高良姜素对黄嘌呤氧化酶靶点占有率的模拟分析

目的:模拟分析黄芩素、槲皮素、高良姜素对黄嘌呤氧化酶体内靶点占有率。方法:通过体外酶促反应测定非布司他、黄芩素、槲皮素、高良姜素对黄嘌呤氧化酶的半数抑制浓度(IC_(50)),利用分子对接技术对其结合自由能进行预测,同时,采用表面等离子共振技术测定其结合速率常数(k_(on))和解离速率常数(k_(off))。基于测定的结合动力学参数和提取的药物代谢动力学数据建立体内靶点占有率模型。结果:非布司他、黄芩素、槲皮素、高良姜素对黄嘌呤氧化酶的IC_(50)分别为0.0027,1.63,0.38,1.59μmol·L^(-1),非布司他的IC_(50)与文献报道一致。预测的非布司他体内靶点占有率曲线与其临床药效持续时间相吻合。当大鼠按100 mg·kg^(-1)单次灌胃给予槲皮素长循环脂质体时,体内靶点占有率>70%的持续时间约3.9 h;当大鼠按200 mg·kg^(-1)单次口服给予黄芩素和高良姜素时,体内靶点占有率>50%的持续时间分别约为10,1.7 h。结论:利用药靶结合动力学和体内药代动力学曲线建立的黄嘌呤氧化酶靶点占有率预测模型能有效地评估化合物对靶点的体内抑制活性。