聚合物微球在油田深部调驱技术中的研究进展

深部调驱技术作为目前提高低渗非均质油藏采收率的有效办法之一,聚合物微球因具有良好的封堵性能和深入性能得到了广泛研究。本文详细介绍了聚合物微球在地层中的深部调驱机理,介绍了聚合物微球的制备方法,综述了聚合物微球的研究内容和研究现状,并指出引入纳米材料合成功能性聚合物微球能有效解决聚合物微球的稳定性,对低渗油藏后期开发具有重要意义。     

Stochastic Spatial Heterogeneity in Activities of H+-ATP-Ases in Electrically Connected Plant Cells Decreases Threshold for Cooling-Induced Electrical Responses

H⁺-ATP-ases, which support proton efflux through the plasma membrane, are key molecular transporters for electrogenesis in cells of higher plants. Initial activities of the transporters can influence the thresholds of generation of electrical responses induced by stressors and modify other parameters of these responses. Previously, it was theoretically shown that the stochastic heterogeneity of individual cell thresholds for electrical responses in a system of electrically connected neuronal cells can decrease the total threshold of the system (“diversity-induced resonance”, DIR). In the current work, we tested a hypothesis about decreasing the thresholds of generation of cooling-induced electrical responses in a system of electrically connected plant cells with increasing stochastic spatial heterogeny in the initial activities of H⁺-ATP-ases in these cells. A two-dimensional model of the system of electrically connected excitable cells (simple imitation of plant leaf), which was based on a model previously developed in our works, was used for the present investigation. Simulation showed that increasing dispersion in the distribution of initial activities of H⁺-ATP-ases between cells decreased the thresholds of generation of cooling-induced electrical responses. In addition, the increasing weakly influenced the amplitudes of electrical responses. Additional analysis showed two different mechanisms of the revealed effect. The increasing spatial heterogeneity in activities of H⁺-ATP-ases induced a weak positive shift of the membrane potential at rest. The shift decreased the threshold of electrical response generation. However, the decreased threshold induced by increasing the H⁺-ATP-ase activity heterogeneity was also observed after the elimination of the positive shift. The result showed that the “DIR-like” mechanism also participated in the revealed effect. Finally, we showed that the standard deviation of the membrane potentials before the induction of action potentials could be used for the estimation of thresholds of cooling-induced plant electrical responses. Thus, spatial heterogeneity in the initial activities of H⁺-ATP-ases can be a new regulatory mechanism influencing the generation of electrical responses in plants under actions of stressors.     

双丝GMAW焊接的电弧干扰和中断分析

为了进一步了解双丝焊接过程中电弧干扰的规律以及有规律的断弧现象,设计了不同焊接电流参数值的匹配系列试验,同步拍摄了电弧形态并采集了两电弧的电流、电压波形.通过理论推导出的双丝电弧的偏移量公式分析了上述试验结果并得到了基本符合的结论：增大另一电弧与该电弧的电流比例,该电弧中断频率增加.最后将高速摄影拍摄到的电弧图片与采集...     

粉体压制过程密度变化机理及影响因素模拟分析

采用MSC.MARC有限元模拟软件对轴套粉体压制成形过程中粉末的位移走向和粉末位移对生坯相对密度的影响进行研究。同时,研究了不同模壁润滑条件以及不同厚度高度比对生坯密度分布的影响。结果表明,粉体成形过程中模壁摩擦导致的位移滞后效应决定了生坯最终的相对密度分布状况;粉末的位移变化规律与生坯的密度分布相似。随着模壁润滑条件的改善和高度厚度比的增加,生坯的密度分布均匀性得到提高;尤其是采用特殊润滑时,生坯密度均匀性得到了明显的改善。这些为研究粉体压制致密化过程提供了理论参考依据。     

NMR法观测熟食豆制品真空冷却前后水分的迁移与分布

利用低场核磁共振及其成像技术,研究经真空冷却的熟食豆制品中水分的状态、分布和迁移情况.通过分析四种豆制品中不同状态的驰豫时间和MR/成像测试图可判定:熟食豆制品中存在三种状态水,分别为结合水、吸附水和自由水;真空冷却前后,结合水(T21)处于相对稳定状态,发生变化的主要是吸附水(T22)和自由水(T23),吸附水和自由...     

基于LF-NMR的香芋微波真空干燥中水分扩散特性研究

为了研究香芋片微波真空干燥过程中水分扩散特性,采用微波真空干燥箱在1.5、2.0和2.5 W/g 3个微波强度下对香芋片进行了干燥试验,利用低场核磁共振技术测定了香芋片微波真空干燥过程中水分迁移及分布情况。结果表明,香芋片微波真空干燥过程主要为降速阶段,3种微波强度下平均干燥速率为0.149、0.185和0.224 g/(g·min);有效水分扩散系数为7.30×10-9、9.46×10-9、1.14×10-8m~2/s。NMR T2谱显示,香芋中存在结合水、不易流动水和自由水3种状态,其横向弛豫时间分别为T21 (2.31～9.32 ms),T22 (10.72～49.77ms)和T23 (57.22～705.48 ms)。干燥过程中,MVD香芋内自由水含量显著降低(p0.05),不易流动水所占比例呈现先增加后下降的趋势,结合水含量变化不显著(p0.05),所占比例逐步上升。MRI检测表明,MVD香芋内外同时失水,且微波强度越高,弛豫信号消失的越快。该研究揭示了微波真空干燥中香芋内水分扩散规律,即微波强度越高,样品内水分扩散速率及不同组分水分之间的转化越迅速。该研究为香芋的微波真空干燥产业化生产提供理论依据。     

酶联适体分析法检测葡萄酒中的赭曲霉素A

建立了竞争取代酶联适体分析方法,检测葡萄酒中的赭曲霉素A(OTA)。核酸适体和OTA特异性结合导致与核酸适体杂交的短链DNA解链,解离的DNA作为捕获元素,进一步特异性结合辣根过氧化物酶(HRP),HRP催化四甲基二苯胺(TMB)底物显色,测定A450nm与浓度的线性关系,确定OTA的检出限。考察了DNA包被浓度、杂交温度和封闭液等因素对检测的影响。结果表明,在优化的条件下,所建立的竞争取代酶联适体分析法对OTA检测有高灵敏度,检测限0.88μg/L,线性范围1~100μg/L在葡萄酒中添加时,加标回收率为92.03%~106.6%,相对标准偏差RSD(n=5)小于2.1%,此方法可用于葡萄酒中OTA的快速测定。     

表面等离子共振法传感器快速检测农药残留的研究进展

为确保农产品质量安全, 发展高灵敏检测技术对农药残留进行检测尤为重要。本文简要介绍了表面等离子共振(surface plasmon resonance, SPR)传感器的原理和增强SPR检测灵敏度的方法, 重点综述了国内外应用SPR传感器检测农药残留的研究现状, 分析了SPR检测农药残留的优势和发展趋势。     

白背三七多糖的分离纯化

采用D315弱碱性阴离子交换树脂和Sephadex G-25凝胶柱层析,从白背三七叶粗多糖中分离纯化得到中性多糖GDPs-1、GDPs-2及酸性多糖GDPs-3 3个多糖组分。经高效凝胶色谱测定,重均分子质量分别为：1.06×104、4.17×103D和3.74×103D;纯度分别为94.08%、92.3%和99.8%。红外光谱证明3种多糖均含有多糖类特征吸收峰,初步推测GDPs-1中α和β构型并存,GDPs-2和GDPs-3为α构型;核磁共振结果进一步证实3种多糖中均只含有α构型。