含碳冷固结团矿还原性测定方法探讨

含碳冷固结团矿与天然铁矿石、烧结矿、氧化球团矿不同、其还原性不能用减量法直接测定，需要根据还原后试样的化学成分计算获得，或根据试样中碳量的变化和试样的减量计算获得，但还原速率指数无法得到，本文以沙城铁厂试样为例进行了说明。     

Characterization of an ovarian cancer activating factor in ascites from ovarian cancer patients

Ascites from ovarian cancer patients contain potent growth-promoting activity toward human ovarian cancer cells both in vitro and in vivo. This activity is associated with rapid increases in cytosolic free calcium ([Ca2+]i) as a consequence of phosphoinositide hydrolysis. In this study, we describe the purification, characterization, and identification of an ovarian cancer activating factor (OCAF) from ascites of ovarian cancer patients. We have isolated OCAF by a combination of solvent extraction, silica gel chromatography, and TLC. Mass spectral analysis, phospholipase sensitivity, and gas chromatographic behavior of purified OCAF indicate that OCAF is composed of various species of lysophosphatidic acid (LPA), including LPAs with polyunsaturated fatty acyl chains (linoleic, arachidonic, and docosahexaenoic acids). However, OCAF is more potent than sn-1 palmitoyl, oleoyl, or stearoyl LPA in increasing [Ca2+]i in ovarian cancer cells. The ability of OCAF to alter [Ca2+]i is sensitive to the effects of lipoxidase, whereas the activity of sn-1 oleoyl, stearoyl, or palmitoyl LPA is not, suggesting that polyunsaturated bonds in the fatty acyl chain of OCAF may account for its increased ability to activate ovarian cancer cells. Furthermore, a sn-2 linoleoyl LPA generated by phospholipase A1 treatment of synthetic phosphatidic acid is much more active than are sn-1 palmitoyl, stearoyl, or oleoyl LPA in increasing [Ca2+]i in ovarian cancer cells. Taken together, these data suggest that the ability of OCAF to increase cellular calcium may reside in the structure and/or location of the fatty acyl chain of LPA. Purified OCAF, at concentrations similar to those present in ascites from ovarian cancer patients, was sufficient to induce proliferation of ovarian cancer cells, as indicated by thymidine incorporation, reduction of 3-(4,5-dimethylthiazol-2-yl)-2, 5-diphenyltetrazolium bromide, or colony formation. However, even at optimal concentrations of OCAF, proliferation was lower than that induced by FCS or ascites from ovarian cancer patients, indicating that, although OCAF may be a major regulator of ovarian cancer cells in vivo, it is not the sole mediator present in ascites, and it likely functions in concert with other growth factor activities.     

Flow reversal in the descending aorta: a guide to intraoperative assessment of aortic regurgitation with transesophageal echocardiography

This study assessed the value of biplane transesophageal echocardiographic assessment of diastolic flow reversal in the descending aorta as an alternative to Doppler color flow imaging in determining severity of aortic regurgitation. In 45 patients undergoing cardiac operations, the severity of aortic regurgitation was assessed by semiquantitative grading of the width of the Doppler color flow regurgitant jet relative to the left ventricular outflow tract, and the presence of diastolic flow reversal was assessed with pulsed-wave Doppler measurements at three sites in the descending aorta. In four patients, the diastolic flow reversal method was the only available form of assessment because of inadequate visualization of the left ventricular outflow tract beneath a mitral valve prosthesis. Diastolic flow reversal in the descending aorta was not observed in patients without aortic regurgitation and was always present in patients with severe aortic regurgitation. Aortic valve replacement successfully eliminated descending aortic flow reversal in all 19 patients in whom it was present before valve replacement. Identification of diastolic flow reversal at multiple sites in the descending aorta with biplane transesophageal echocardiography helps to confirm the presence of severe aortic regurgitation and can serve as an alternative method of assessment when visualization of the left ventricular outflow tract is impaired.     

异步时序型PAL解析方法的研究及解析结果分析

本文就异步时序现ＰＡＬ的解析，提出了一种状态图遍历算法。     

一个全数字化交流永磁伺服系统

介绍了开发的全数字交流伺服系统的组成、基本原理及软、硬件结构。通过与模拟交流伺服系统的比较，说明了全数字交流伺服系统可编程能力强、系统稳定性好、系统性能提高等特点。     

铜蒸汽激光器双闸流管触发系统的研究

研制成用于钢蒸汽激光器的双间流管触发系统。用两个闸流管并联进行交替触发，总输入电功率达7．8kW。低功率运行时，激光器的效率为0．6％与单间流管激光器的效率一致。     

特种人造纤维微观结构的扫描电镜观察和研究

本文以吸湿睛纶、双层纤维，中空纤维，酚醛纤维和阻燃纤维等特种人造纤维为研究对象，用扫描电子显微镜观察和研究了它们各自的微观形态，结构特点和性能。提出了一些认识，以便为纺织业和印染业的生产工艺提供可靠的科学依据。