The extraction of platinum from Pt(II) chloride solution by a quaternary ammonium compound

The fundamental aspects of the extraction and stripping of platinum (II) from its chloride solution by Aliquat 336 diluted with toluene have been studied. The extraction and stripping was at 99.5 and 97.6% equilibrium within 30 s and 20 min respectively. The percentage extraction increased slightly with decreasing hydrochloric acid concentration. In 0.1 mol dm^?3 hydrochloric acid, 1.0 volume percent Aliquat 336 in toluene could load 9.8 mmol dm^?3 of platinum (II). The percentage stripping of platinum (II) from Pt(II)-load organic solvent increased with increasing sodium bisulphite concentration. The enthalpy changes of extraction and of stripping were 12.8 and 114.9 kJ mol^?1 respectively. Both of the reactions were endothermic.     

On the current-voltage characteristics of epitaxial Schottky barrier diodes

The J-V characteristics of epitaxial Schottky barrier diodes are analyzed. Based on the assumption of negligible recombination in the epitaxial layer, formal solution from which the J-V characteristics can be calculated is derived. The solution is valid for all injection levels and reduces to the form I = I_s[exp (q(V?IR)/kT) ? 1], where R is the series resistance of the epitaxial layer, under C12 C12V low-injection conditions. The analysis is justified by very close correspondence with exact numerical calculations using the Finite Element Device Analysis Program (FIELDAY) in which thermionic emission boundary conditions are implemented for both electrons and holes. It is shown that for low barrier Schottky diodes the minority carrier injection is negligible and the expression I = I_s[exp (q(V?IR)/kT) ? 1] describes the I-V characteristics over large bias range. For high barrier C12 C12 V Schottky diodes the exact solution must be used as minority carriers are injected and the series resistance is decreased due to conductivity modulation effect.     

Soft-output equalization and TCM for wireless personalcommunication systems

This paper investigates the use of a maximum a posteriori probability (MAP) algorithm to realize soft-output equalization in a concatenated equalization and trellis-coded modulation (TCM) decoding-based wireless communication system. Specifically, we first begin with a general MAP algorithm and then focus on studying Bahl's (1974) MAP and Lee's (1974) MAP algorithms. We then propose a modified version of Lee's MAP algorithm which is much simpler than the original, in terms of complexity, and is more practical. In particular, a very simple channel estimation method which employs orthogonal training sequences is proposed. In order to improve the system performance, equal-gain combining and selection diversity are also considered. Finally, we compare the performance of the MAP algorithm-based equalization with our previously proposed equalization scheme, which combines decision feedback equalization and TCM     

Identification of heat load loops and downstream paths in heat exchanger networks

To achieve the optimal trade-off between economies and operability, simplifications of heat exchanger networks (HENs) are required. To do so, identifications of heat load loops and downstream paths are necessary. This paper proposes new methods for identifications of independent and dependent loops as well as downstream paths in HENs, respectively. Stream table and node adjacency matrix are defined in this paper to represent the structures of HENs. Based on graph theory, identification of loops in HENs is decomposed into three procedures: (a) finding a maximal tree, (b) identifying a maximal set of independent loops and (c) searching all loops. Locating the downstream paths in HENs is accomplished by finding directed trees which are generated by modifying the procedure for finding a maximal tree. A complex network with a splitting stream is used for detailed illustrations of the procedures.     

规格说明语言ChiSL

ＣｈｉＳＬ是一种作用式可执行的功能规格说明语言，它是以数据抽象为核心的将代数规格说明和面向模型的规格说明两种技术有机地结合起来的模块化语言，具有良好的数据性质和可读性，能比较方便地书写大型规格说明?由于该语言是可执行的，因此ＣｈｉＳＬ规格说明可作为所要开发的软件系统的一个原型在该语言的支撑系统上执行。本文后面介绍了使用ＣｈｉＳＬ语言及其支撑系统开发软件原型的一些应用实例。     

紧凑型K波段单级反馈式MMIC中功率放大器

给出了一种基于功率PHEMT工艺技术设计加工完成的紧凑型K波段单级反馈式MMIC宽带功率放大器.在21～28GHz的工作频段内,当漏极电压为6V,栅电压为-0.25V,电流为82mA时,1dB压缩点输出功率大于21dBm,小信号增益为7dB左右,输入驻波比小于3,输出驻波比均小于2.芯片尺寸为1mm×1.2mm×0.1mm.同时,给出了一种芯片级电磁场仿真验证方法,用该方法仿真的结果和测试结果非常一致,保证了电路设计的准确性.     

Distinct clinicopathologic characteristics of diffuse- and intestinal-type gastric cancer in Taiwan

The clinicopathologic features of 221 patients with intestinal-type (IT) gastric cancer were compared retrospectively with those of 290 diffuse type (DT). Intestinal type was characterized by an older mean age (65.0 +/- 10.8 years vs. 56.2 +/- 13 years), a higher male-female ratio (2.56 vs. 1.06), predominance of blood group O (46.2% vs. 31.1%), and frequent habitual smoking (50.7% vs. 31.4%) and drinking (28.5% vs. 17.6%) than did DT. In contrast, DT had a higher frequency of positive history of parent or sibling with gastric cancer (9.3% vs. 4.1%) and blood group A (40.3% vs. 27.6%) than did IT. The distinguishing histologic features of DT included more Borrmann type IV (13.1% vs. 1.3%) but less Borrmann type I (1% vs. 7.2%), more frequent involvement of middle third (26.9% vs. 15.9%) and whole stomach (4.1% vs. 0%), and more peritoneal seeding (15.5% vs. 9%), lymph node metastasis (67.2% vs. 51%), and nerve permeation (34.1% vs. 24.4%), but less Helicobacter pylori infection (55.9% vs. 69.2%) when compared with those of IT. There was no difference in depth of tumor invasion, venous permeation, duodenal involvement, and postoperative survival between IT and DT. These distinct clinicopathologic features between IT and DT in Taiwan suggest the presence of a different pathogenic process for these two histologic subtypes of gastric cancer.     

Factors associated with the therapeutic efficacy of retinoic acids on malignant lymphomas

We recently reported the successful use of retinoic acids in the treatment of refractory lymphoma. The biologic determinants predicting response of lymphomas to retinoic acid remain unknown. This study was conducted to explore this question using in vitro models. Sensitivity of representative lymphoma cells to 13-cis-retinoic acid was determined. Sensitive and resistant cell lines were then compared for their baseline and/or retinoic-acid-regulated expression of total cellular retinoic acid binding protein, retinoic acid receptor (RAR)-alpha, RAR-beta, RAR-gamma mRNA, retinoid X receptor (RXR)-alpha, RXR-beta, RXR-gamma mRNA, transforming growth factor (TGF)-beta 1 and TGF-beta 1 receptors, and Fas (Apo-I) mRNA. The results showed that four of five T, two of three Hodgkin's, and none of six B cell lymphoma cell lines were sensitive (IC30 < 1.5 mmol/L) to 13-cis-retinoic acid. Further analyses revealed several of the above-mentioned parameters may be relevant to retinoic acid sensitivity. Baseline expression of TGF-beta 1 receptors was present in all of the five sensitive cell lines examined, but in only one of the four resistant cell lines. The correlation of Fas expression and retinoic acid sensitivity was good for B cell lines, but not apparent for T cell or Hodgkin's cell lines. On exposure to retinoic acid, an immediate and prolonged upregulation of RAR-alpha mRNA expression, lasting for more than 12 hours, occurred in all sensitive cell lines, but only minimal or transient induction was seen in resistant cells. Together, these data suggested that; 1) retinoic acid has a preferential effect on T cell and Hodgkin's lymphoma cell lines; 2) autoregulation of RAR-alpha by retinoic acids, and the presence of TGF-beta 1 receptors may be relevant to the response of lymphomas to treatment with retinoic acids.     

The effect of education on mortality among older Taiwanese and its pathways

The present research examines the impact of education on the mortality of older Taiwanese during a 4-year interval from April 1989 to April 1993. Data used for this study come from the Taiwan Survey of Health & Living Status of the Elderly (1989). The research decomposes the effect of education into the direct effect and the indirect effects by means of health status, health behaviors, and social relationships. We have shown that, of the total effect of educational attainment on the mortality of older Taiwanese, about 83% represents indirect influences by means of the 3 mediating factors, particularly health status. On the other hand, the magnitude of the direct effect, which might reflect influences of additional intervening variables on old-age mortality, is low and not statistically significant. The results demonstrate that the apparent strong effect of education on mortality among older Taiwanese can be accounted for parsimoniously through 3 major pathways.