Uptake characteristics of loracarbef and cephalexin in the Caco-2 cell culture model: effects of the proton gradient and possible presence of a distinctive second component

The mechanisms of apical (AP) uptake of cephalexin (CEPH) and loracarbef (LOR) in the absence or presence of an (extemally imposed) proton gradient were determined using well-stirred diffusion chambers that minimize the effects of the unstirred water layer. The results indicated that, compared to AP uptake in the presence of an imposed proton gradient, AP uptake in the absence of an imposed proton gradient had higher K(m) values and lower Jmax values. Furthermore, when inhibition studies were performed in the absence of a proton gradient, only natural peptides were effective, whereas the peptide analogs (e.g., enalapril) were not. In addition to the effects of concentration and competitive inhibitors, the results also indicated that (1) the AP uptake of both drugs was decreased more than 60% by FCCP, regardless of whether the proton gradient was present or absent; (2) effects of protein kinase C promoter were dependent upon the presence of a proton gradient; and (3) AP uptake in the presence of an imposed proton gradient was not affected by feeding restriction, whereas AP uptake in the absence of an imposed proton gradient was. These results showed for the first time that two substrates with similar AP uptake characteristics in the presence of an imposed proton gradient may not share those characteristics in the absence of an imposed proton gradient. Taken together, these results suggest that the AP uptake component that functions in the absence of an imposed proton gradient is distinctly different from the one that functions in the presence of an imposed proton gradient. Data generated from the present study and those in the literature lend support to the hypothesis that this distinctive component represents the second binding site on the AP peptide transporter. However, an alternative hypothesis that there are two AP peptide transporters remains to be disapproved.     

工业汽轮机的清洗

本文介绍了用饱和蒸汽对冷凝式汽轮机进行清洗除垢时主要参数的确定、操作要点及清洗方案，清洗后的汽轮机运行正常。     

用于实时测量负重轮轮胎温度场的红外遥测系统

为研究坦克装甲车辆行使过程中负重轮轮胎内部的温度分布，研制了一种用于实时测量轮胎内部温度的多路遥测装置。该装置温度信号的传输采用了红外线无线光通信技术，免去了连线，可广泛应用于旋转件中及其它不便连线场合测量信号的传输。该文详细介绍了这一装置的工作原理及各部分的关键技术。     

Determination of assimilable organic carbon (aoc) in ozonated water with acinetobacter calcoaceticus

The effect of ozone application in drinking water on the production of assimilable organic carbon (AOC) was evaluated. The typical procedure to determine AOC is suggested by van der Kooij, which is the method of bacterial growth measurement by colony‐forming units using the strain P17 and/or NOX. The bacterial indicator species used for this study is Acinetobacter calcoaceticus which was isolated and identified while ozonating Nakdong river water. This strain could never be isolated from the raw water, but this strain was the predominant isolate in the ozonated water. Within a short incubation time, this organism was found to replicate well on acetate and oxalate as the sole carbon sources. The yield coefficients of this organism for acetate and oxalate are the same order of magnitude as the value of P17 and NOX. With full‐scale experiments, A. calcoaceticus concentration was found to increase after ozonation, but did not decrease upon chlorination. In laboratory‐scale experiments with Yongsan river water, aldehyes were found to be produced in proportion to the ozone dose. The raw water contains low concentrations of aldehydes, but has a high AOC concentration. A correlation between aldehyde production and AOC production was observed in the tested water with ozonation.     

复合棒弯曲振动的矩阵解法

按组成材料和横截面大小的不同，把复合棒分成若干单元，每单元两端的位移，截面转角，弯矩以及剪力间的关系用矩阵表示，各单元矩阵相乘即复到复合棒总的矩阵，最后由此求解复合棒的共振条件，以及两端振速比，还给出了应用例。     

重力坝深(底)孔断面钢筋混凝土模型试验研究

文通过7个小尺寸和1个大尺寸的钢筋混凝土断面模型试验，研究重力坝深(底)孔在坝体自重和内水压力以及超内水压力作用下的结构特性和破坏规律。重点探讨混凝土和钢筋应力应变、混凝土开裂、裂缝宽度和裂缝扩展规律，为建立更为科学的孔口配筋理论提供依据。     

光盘用光学头物镜性能的综合评估

论述了采用波象差均方根、点扩展函数、光学传递函数对高次旋转对称非球面光学头物镜性能进行综合评估的方法。作者在正则坐标理论基础〔１〕上编制了光学头物镜性能综合评估软件。给出了评估实例。     

ATM交换机的硬件体系结构探讨

本文首先对ＡＴＭ的背景作了一个简单的介绍，接着阐述了ＡＴＭ和ＡＴＭ交换机的主要原理和技术，然后从硬件系结构的角度具体地分析了一种实验ＡＴＭ交换机是怎样ＡＴＭ技术的详细方法。     

陕甘宁盆地中部奥陶系风化壳储层特征

陕甘宁盆地中部奥陶系风化壳碳酸盐岩储集层属于古岩溶型,主要储集空间是溶蚀孔洞。本文根据古岩溶成因及发育特征,利用毛细管压力曲线、铸体薄片、阴极发光及物性分析资料,综合研究了碳酸盐岩储层参数及其分布特征,探讨了孔、洞、缝组合关系并划分出4种储层类型,判别了储层的有效性,为天然气勘探及储量计算提供了地质基础资料。