厂用电源切换探讨

国内以往发电厂的厂用电源自动投入装置都为慢速切换。但现在随着大容量电动机的增加,大容量电动机在断电后电压衰减较慢,残余电压的幅值很大,给厂用电源的切换带来许多问题。传统的BZT(备自投)切换装置采用的是慢速切换,因为没有检测相位回路,这种切换方式的成功率低、冲击电流大,造成6kV厂用电电源中断的事故频频发生。文中对厂用电源的切换方式(慢切和快切)进行了分析,并对提高厂用电源切换可靠性和稳定性提出了一些建议。

厂用电6kV快切装置动作分析与改进

发电厂中,厂用电的安全可靠直接关系到发电机组、电厂乃至整个电力系统的安全运行。分析了高压厂用备用电源自动切换中存在的问题。通过南通华能电厂中快切装置的定值整定计算和快切试验分析,可知备用电源快速切换装置可有效避免备用电源电压与母线残压在相角、频率相差过大时合闸而对电动机、变压器等电器设备造成冲击,并通过慢切提高厂用电切换的成功率。

6kV系统厂用快切装置可行性方案

本文主要介绍6kV系统厂用电快切装置在化工企业厂中的作用,结合企业用电事例,解决110kV内网和主变单线故障带来失电问题,保证化工生产的持续性供电。

核电站核岛中压配电盘内燃弧故障保护研究

介绍了配电盘内燃弧故障产生的原因、危害及预防措施,分析了岭澳核电站(二期)中已经采用的内燃弧保护配置。在研究中压配电盘二次接线图及中压配电系统逻辑图的基础上,提出了将中压内燃弧保护和中压厂用电系统切换逻辑相结合的保护方案。

Selection criteria for liver resection in patients with hepatocellular carcinoma and chronic liver disease

Hepatocellular carcinoma (HCC) is one of the most common malignancies worldwide with an annual occurrence of one million new cases. An etiologic association between HBV infection and the development of HCC has been established with a relative risk 200-fold greater than in non-infected individuals. Hepatitis C virus is also proving an important predisposing factor for this malignancy with an incidence rate of 7% at 5 years and 14% at 10 years. The prognosis depends on tumor stage and degree of liver function, which affect the tolerance to invasive treatments. Although surgical resection is generally accepted as the treatment of choice for HCC, new treatment strategies, such as local ablative therapies, transarterial embolization and liver transplantation, have been developed nowadays. With increasing detection of small HCCs from screening programs for cirrhotic patients, it is foreseen that locoregional therapy will play an important role in the near future.

Gastrectomy for patients with gastric cancer and non-uremic renal failure

AIM： To investigate the safety and outcome of gastrectomy for patients with gastric cancer and nonuremic renal failure （NURF）.METHODS： One hundred forty-seven patients who underwent gastrectomy for carcinoma were retrospectively divided into two groups： a group with Ccr values of ≥ 50 mL/min （Group 1, n = 110）, and one with Ccr values of ≥ 20 to 〈 50 mL/min （Group 2, n = 37）. Preoperative patient characteristics, intraoperative parameters （including operation time and blood loss）, and postoperative management and complications were evaluated.RESULTS： There were no statistically significant differences between the two groups in operation time （297.9 rnin vs 272.6 rnin, P = 0.137） or blood loss （435 rnL vs 428 rnL, P = 0.078）. The differences in postoperative complications and hospital stay between the groups were not statistically significant. None of the patients in Group 2 required dialysis therapy, and no patients died due to gastrectorny or gastrectorny-related causes. The overall 4-year survival rates in Groups 1 and 2 were 86.6% and 81.8%, respectively （P = 0.48）, and the corresponding 4-year disease-free survival rates for stage I, I, and Ⅲ patients were 88.7% and 83.5%, respectively （P = 0.65）.CONCLUSION： Gastrectomy can be performed as safely in patients with NURF similar to patients with normal renal function.

THROMBOENDARTERECTOMY FOR CHRONIC PULMONARY THROMBOEMBOLISM

Objective To evaluate the improving reliability and safety of thromboendarterectomy and perioperative management for chronic pulmonary thromboembolism. Methods The clinical data of 12 cases with chronic pulmonary thromboembolism, who underwent thromboendarterec- tomy assisted by low flow or circulation arrest with deep hypothermia, were reviewed retrospectively. Results Pulmonary artery pressure decreased 20 to 40 mmHg immediately after surgical procedures in 9 cases. The postoperative pulmonary edema at various degrees happened in 12 cases, among them, 1 died of severe lung infection and pulmonary re-embolism at 19 days postoperation. Computed tomography pulmonary angiography and angiography of 11 cases indicated that the original obstruction of pulmonary artery disappeared. During the follow-up period of 2 months to 5 years, the clinical symptoms and activity was improved. Conclusion Thromboendarterectomy is an effective treatment for chronic pulmonary thromboembolism. The outcome of the surgical procedure needs to be further investigated and followed up regularly according to an evaluative system, because it might be influenced by multiple factors.

Effect of NCPB and VSPL on pain and quality of life in chronic pancreatitis patients

AIM: To compare the effects of neurolytic celiac plexus block (NCPB) and videothoracoscopic splanchnicectomy (VSPL) on pain and quality of life of chronic pancreatitis (CP) patients.METHODS: Forty-eight small duct CP patients were treated invasively with NCPB (n = 30) or VSPL (n = 18) in two non-randomized, prospective, case-controlled protocols due to chronic pain syndrome, and compared to a control group who were treated conservatively (n = 32). Visual analog scales were used to assess pain and opioid consumption rate was evaluated. In addition, the quality of life was measured using QLQ C-30 for NCPB and FACIT for VSPL.Although both questionnaires covered similar problems,they could not be compared directly one with another.Therefore, the studies were compared by meta-analysis methodology.RESULTS: Both procedures resulted in a significant positive effect on pain of CP patients. Opioids were withdrawn totally in 47.0% of NCPB and 36.4% of VSPL patients,and reduced in 53.0% and 45.4% of the respective patient groups. No reduction in opioid usage was observed in the control group. In addition, fatigue and emotional well-being showed improvements. Finally, NCPB demonstrated stronger positive effects on social support, which might possibly be attributed to earlier presentation of patients treated with NCPB.CONCLUSION: Both invasive pain treatment methods are effective in CP patients with chronic pain.

Endoscopic sphincterotomy in patients with stenosis of ampulla of Vater:Three-year follow-up of exocrine pancreatic function and clinical symptoms

AIM: To investigate retrospectively the long-term effect of endoscopic sphincterotomy (ES) including exocrine pancreatic function in patients with stenosis of ampulla of Vater. METHODS: After diagnostic endoscopic retrograde cholangiopancreatography (ERCP) and ES because of stenosis of the ampulla of Vater (SOD Type Ⅰ), follow-up examinations were performed in 60 patients (mean follow-up time 37.7 mo). Patients were asked about clini-cal signs and symptoms at present and before interven-tion using a standard questionnaire. Before and after ES exocrine pancreatic function was assessed by determina-tion of immunoreactive fecal elastase 1. Serum enzymes indicating cholestasis as well as serum lipase and amy-lase were measured. RESULTS: Eighty percent of patients reported an im-provement in their general condition after ES. The fecal elastase 1 concentrations (FEC) in all patients increased significantly after ES. This effect was even more marked in patients with pathologically low concentrations (< 200 μg/g) of fecal elastase prior to ES. The levels of serum lipase and amylase as well as serum alcaline phosphatase (AP) and gamma-glutamyltranspeptidase (GGT) decreased signifi-cantly after ES. CONCLUSION: The results of this study demonstrate that patients with stenosis of the ampulla of Vater can be successfully treated with endoscopic sphincterotomy. The positive effect is not only indicated by sustained improvement of clinical symptoms and cholestasis but also by improvement of exocrine pancreatic function.

Risk factors for post-hepatectomy liver dysfunction in primary liver cancer patients with concurrent hepatic schistosomiasis and chronic hepatitis

Objective:The purpose of this study was to analyze risk factors for development of post-hepatectomy liver dysfunction in primary liver cancer(PLC)patients with concurrent hepatic schistosomiasis and chronic hepatitis.Methods:A retrospective analysis of 73 PLC patients with concurrent hepatic schistosomiasis and chronic hepatitis,of which 16 patients developed liver dysfunction(persistent ascites or pleural effusion or occurrence of liver-related potentially fatal complications)following hepatectomy,was performed.After clinical characteristics were recorded,preoperative liver function parameters and surgery-related parameters in these patients were assessed.Seventeen potential risk factors for post-hepatectomy liver dysfunction were identified.The association between these potential risk factors and post-hepatectomy liver dysfunction then was analyzed.Results:Univariate analysis showed that liver cirrhosis,intraoperative blood loss,and preoperative total bilirubin were associated with the development of post-hepatectomy liver dysfunction.Multivariate logistic regression analysis of these three factors revealed that intraoperative blood loss≥600 mL and cirrhosis were two independent risk factors for post-hepatectomy liver dysfunction in PLC patients with concurrent hepatic schistosomiasis and chronic hepatitis.Conclusion:Keeping intraoperative blood loss below 600 mL can help avoid the development of post-hepatectomy liver dysfunction in liver cancer patients with concurrent hepatic schistosomiasis and chronic hepatitis.For patients with concomitant liver cirrhosis,every effort should be made to minimize potential liver function impairment induced by other adverse factors.