固相分散萃取-液相色谱法测定豆沙中的富马酸二甲酯

采用固相分散萃取技术对豆沙样品进行预处理,用高效液相色谱法测定其中的富马酸二甲酯。Diamonsil C18色谱柱,柱温25℃,甲醇-水（体积比为55∶45）作流动相,流速1.0mL/min,检测波长220nm。富马酸二甲酯在0.136μg/mL～33.5μg/mL范围内线性良好,相关系数为0.9998,方法检出限0.82μg/g,平均回收率82.5%,相对标准偏差为3.3%。市售豆沙馅中未检出富马酸二甲酯。     

造纸填料的包覆改性——提高加填纸张的强度性能

加填可改善纸张性能、降低抄造成本,但加填也会降低纸张强度。利用与纤维素纤维具有结合能力的材料对填料进行包覆改性是降低填料对纸张强度的不利影响、提高纸张加填量的重要途径。本文就淀粉、壳聚糖和纤维素对常规填料的包覆改性进行了较为详细的介绍。其中淀粉由于价格低廉、包覆改性后强度改善效果显著,是应用潜力最大的填料包覆改性材料。     

Waves in nonlocal thermoelastic solids of type II

The present article deals with the investigation of the propagation of thermoelastic plane harmonic waves in a nonlocal thermoelastic medium. The Green and Naghdi theory II (without energy dissipation) of generalized thermoelasticity with elastic nonlocal effect is adopted to address this problem. The problem of reflection of thermoelastic waves due to an incident coupled longitudinal elastic wave from the rigid and thermally insulated boundary of a homogeneous, isotropic nonlocal thermoelastic half-space is also studied. The amplitude ratios of the reflected waves and their respective energy ratios are determined analytically. For a particular model, the effect of elastic nonlocality parameter on the variations of phase speeds, attenuation coefficients, amplitude ratios and corresponding energy ratios of the reflected waves is presented graphically and analysis of these results is given.     

Simulation of Flow and Mass Transport in a Meander Microchannel Subject to Electroosmotic Pumping

We have investigated the flow and mass transport within an electroosmotically pumped incompressible liquid through a meander microchannel system. We employ two-dimensional, time-dependent finite element simulations in conjunction with a matched asymptotic treatment of the electrical double layers. The electroosmotic pumping is realized for two idealized and two realistic electrical fields, while a pressure-driven flow is used for comparison. We focus on the aspects of the electroosmotic transport.

We find for most of the electroosmotically driven cases rather complex flow fields, involving recirculation regions. These recirculation regions in all cases increase dispersion. (i) The least dispersion is associated with a plug-type velocity profile, which is obtained for an idealized purely wall-tangential orientation of the electrical field. (ii, iii) We find that both the idealized horizontal electrical field and the real electrical field between two vertical plates give considerably higher dispersion than the pressure-driven flow. Vertical plate electrodes, therefore, do not allow for a electrical field, which minimizes dispersion. (iv) The arrangement of two point electrodes at the in and out sections likewise proves to be no optimal means to reduce dispersion beyond the pressure-driven flow. Thus, meander geometries of channels, in general, cause severe problems if electroosmotic pumping needs to be achieved in combination with minimized dispersion.     

Oviposition decisions in the seed beetle, Callosobruchus maculatus (Coleoptera: Bruchidae): effects of seed size on superparasitism

The seed parasite Callosobruchus maculatus generally disperses eggs uniformly among seeds. We used cowpeas (Vigna unguiculata) of two class sizes (large and small) to test predictions based on a simple resource threshold model that females will distribute eggs among seeds in a manner that maximizes the amount of resources allocated to each offspring. When females were presented with multiple seeds of the same size, they tended to distribute their eggs relatively uniformly among seeds (I?0.27 where I is the variance/mean ratio, and I=1 reflects a random Poisson distribution). However, when seeds varied in size females distributed their eggs in a manner that maximized the amount of resources per offspring; females distributed eggs as predicted by seed differences in mass rather than as predicted by seed differences in surface area. Therefore, females must evaluate the relative quantity of resources available inside of a seed more accurately than if they compared the ratio of surface areas between seeds of varying size. Instead, females must either use cues other than surface area when estimating seed mass, or must have the ability to extrapolate non-linearly from surface area to seed mass. Females with higher egg loads (4-d-old females) laid more eggs when presented with seeds, but did not distribute their eggs less uniformly, than females with lower egg loads (1-d-old females), indicating that high egg load does not reduce female sensitivity to seed size and the presence of conspecific eggs.     

干法阳离子淀粉作电荷中和剂提高填料留着率

主要研究了干法制备高取代度阳离子淀粉的方法，将玉米原淀粉和适量的碱催化剂在混合容器中混合均匀后，再加入3-氯-2-羟丙基三甲基氯化铵阳离子醚化剂，在温度为60～80℃时，反应5h，用乙醇溶液浸泡、过滤、洗涤、真空干燥，制得高取代度阳离子淀粉，用其作为阴电荷中和剂可提高填料留着率。在造纸过程中具有显的助留效果，且用量明显减少。     

高分子质量阳离子聚丙烯酰胺的合成及其应用

研究采用复合引发体系，以阳离子单体DMC和丙烯酰胺(AM)为共聚单体合成出一系列不同分子质量和不同阳离子化度的阳离子聚丙烯酰胺(CPAM)，并将其应用于造纸湿部。结果表明，自制的CPAM可以显著改善造纸湿部的填料因着率和滤水性能；与膨润土复配后，不仅能提高填料留着率，而且对纸页强度没有不利影响，另外，由动态滤水仪(DDJ)实验得出的单程因着率也有较大提高。     

高浓液相改性膨润土的开发前景

常规改性膨润土作造纸微粒助留剂使用时，在低pH值下既不方便，效率也不高，并且生产轮末状膨润土成本高。因此，造纸中使用高浓液相膨润土有很大的应用潜力。文中综述了各种制备高浓液相膨润土的方法。     

水性聚氨酯分散体的改性探讨

详细讨论了水性聚氨酯分散体 (PUD)改性研究的新进展 ,如交联、利用有机硅氧烷以及丙烯酸树脂改性PUD等。同时对利用纳米材料、纳米技术改性PUD也作了初步探讨和设想。最后指出了水性聚氨酯分散体的发展趋势为高性能、多功能复合型     

平顶山市伊利石在橡胶中的应用研究

平顶山市伊利石矿是河南省首次发与评价的一大型伊利石矿床。通过工业应用研究,用该矿制备的伊利石粉代替轻质炭酸钙,白炭黑作橡胶填料,产品达到国际ＧＢ７０３６－８９质量标准。