宝钢1930板坯铸机二冷喷嘴布置方式对铸坯质量的影响

在对宝钢1930铸机铸坯质量缺陷类型和形成位置分析的基础上，通过喷嘴性能测试和数值模拟计算，重点研究了1930铸机六、七冷却区喷嘴布置方式对铸坯的冷却均匀性和铸坯质量的影响，从解决铸坯角部横裂纹和内部三角区裂纹角度出发，提出了宝钢1930铸机二冷系统进一步改造方案。     

攀钢板坯连铸机二冷区喷嘴特性测试

对连铸二冷区喷嘴的冷态特性进行了研究。测定了不同喷水条件下喷嘴的压力一流量关系,喷水密度分布以及喷射角和喷雾粒度分布。分析了国内外喷嘴的特性曲线,为国内厂家生产喷嘴提供了更为合理的参数。     

昆钢新型板带除鳞装置的改造与应用

针对昆钢1725炉卷轧机生产线中除鳞不彻底的缺陷，通过对板坯炉生氧化铁皮结构特点和除鳞的原理进行分析，结合生产实际，优化喷嘴冲击力、流量和工艺参数。经现场实施应用，实现了良好的除鳞效果，炉生氧化铁皮除鳞率达97％以上，热轧板卷除鳞合格率达99．78％，节约了生产成本，经济效益显著。     

CSP高压水除鳞技术研究

从理论角度分析了氧化铁皮产生及高压水除鳞的机理,从喷嘴喷射打击力和除鳞喷嘴的布置方面结合酒钢CSP的实际应用效果详细讨论了影响板坯除鳞效果的设备因素,对除鳞系统的维护与检查及下一步的改进作了简单的说明。     

特厚板坯连铸机二冷区喷嘴选型与布置

 连铸的二次冷却是影响铸坯质量的重要因素之一,而喷嘴选型和布置对二次冷却均匀性尤为重要。针对厚度大于400mm的特厚板坯生产所具有浇铸速度低、角部温度低、横向温度不均匀、液芯长度偏长等特点,拟定了特厚板坯喷嘴选型及布置的设计要求准则,再基于喷嘴厂提供的喷嘴试验参数和设备设计特点,从喷嘴喷射角度、安装高度、喷嘴间距、布置方式等方面对特厚板坯喷嘴选型与布置进行了分析,并就弱化特厚板坯边部冷却、均匀化水流密度提出了策略。生产实践表明,特厚板坯外形尺寸良好,表面质量无缺陷、内部质量良好。     

连铸板坯二冷区传热数学模型的研究与应用

本文结合板坯连铸机的具体条件，对二冷区各种传热方式进行了分析研究，应用数学方法建立凝固传热方程，并针对使用喷嘴及浇铸钢种，借助于计算机对二冷热制度进行模拟优化，提出配方程为：Ｑ＝７．８１３１５＋４６．４７４３Ｖ＋５７．４２８６Ｖ＾２，经现场应用表明，所制定的水表合理，生产的铸坯质量较好，取得了良好的效果。     

二冷喷嘴类型和布置对板坯质量的影响

对南钢超低头板坯连铸机使用的二冷喷嘴性能测试表明 ,扁平喷嘴喷射水流分布均匀 ,而圆形喷嘴喷射水流分布不均匀 ,易造成板坯侧面凹陷和三角区裂纹。根据二冷仿真软件模拟 10 0 0mm× 180mm板坯冷却过程 ,得出改进工艺模型 :在板坯侧面全部采用扁平喷嘴 ,并将板坯正面喷嘴间距由 2 2 5～ 30 0mm改为180～ 2 0 0mm。应用结果表明 ,生产板坯的优质品率由 86 32 %增至 92 2 2 %。     

喷嘴布置方式对中厚板坯连铸二次冷却效果的影响

研究了铸机矫直区现行喷嘴布置对板坯冷却效果的影响,并在喷嘴自动化测试平台上进行一系列喷嘴的组合实验,从喷嘴流量、喷射高度和水压三个方面探讨了相邻喷嘴喷淋水重叠度与水量在板坯宽度方向分布均匀性的关系.在此基础上,对现行的二次冷却系统提出了优化方案.实验结果表明,优化后,铸坯角部横裂基本消除,铸坯中心偏析从B类1.0减轻至C类1.5,其等轴晶比例提高了4.1%,明显地改善了铸坯的内部质量.     

板坯连铸机二次冷却均匀性的分析与优化

针对某厂连铸板坯裂纹频繁出现的问题,结合连铸机的喷嘴布置特点,在测试分析铸机喷嘴的喷淋冷却特性的基础上,以Q235G钢为对象,考虑板坯宽度方向二冷水流密度分布状态,采用数值仿真方法模拟计算了200 mm×1350 mm连铸坯的凝固壳生长形貌及铸坯表面内弧温度分布.研究表明:板坯铸机二冷前期足辊段与零段原喷嘴布置及水流密...     

影响板坯热喷号机喷号效果因素及应对措施

影响喷号效果的因素有喷嘴气压、喷嘴与铸坯之间距离、喷嘴角度、起弧电压、喂线速度以及铸坯喷号区域是否平整。现场试验喷号结果表明喷嘴气压越小,字迹越模糊,效果越差,尽量使用最大压力喷号;喷嘴与铸坯之间距离越近越喷号效果清晰,但是距离太近融化后的铝末容易将喷嘴堵塞,因此在保证喷号喷嘴不堵塞和字迹不发散的情况下,距离在20mm~25mm效果最好;喷嘴之间距离为3mm~4mm,角度为40℃~45℃喷号效果最好;起弧电压越小,字迹越清晰;喂线速度越慢,字迹越发散。如果铸坯喷号区域不平整或者有毛刺,直接会导致喷号终止并损坏喷号设备。     

Benzimidazole resistance in cyathostomes in horses in the Ukraine

The efficacy of treatment with cambendazole was tested in 1-year-old horses on a farm in Dubrovka, Ukraine. Thirty-five horses were treated. Their egg output was compared on the day of treatment and 14 days later with that of 33 untreated horses. Before treatment the mean number of eggs g-1 faeces was 614 in the controls and 766 in horses that had been treated. After 14 days the mean egg output in the controls was 580 and in the treated horses 369. This means a reduction of 54.5%. Only cyathostome larvae could be cultured from faeces collected after treatment. It can be concluded that benzimidazole resistance in cyathostomes is present in the Ukraine.     

Apoptosis in experimental myocardial infarction in situ and in the perfused heart in vitro

We report the appearance of apoptotic cells in experimental myocardial infarction (rabbit heart) in in situ and in vitro preparations. Apoptosis was recognized by intravital staining with Hoechst 33342 (Ho342), by nick-end labeling (TUNEL) and by DNA laddering. A steady rise in the relative number of apoptotic cardiomyocytes (apoptotic index) was noted in in situ preparations. Apoptosis was first noted 6 h after the onset of ischemia with its highest value occurring after 72 h. Apoptotic nuclei were absent in remote areas of the left and right ventricles. Apoptotic nuclei within the infarcted area showed diminished intensity of Ho342 fluorescence. Three days after ischemia, a border zone adjacent to the infarcted area consisting of apoptotic macrophages was recognized. A novel finding was the appearance of apoptotic cardiomyocytes in the isolated perfused ischemic heart. Occurring as early as 50 min after the onset of ischemia, a high apoptotic index was present adjacent to the ligature placed around the coronary artery. This observation provides the opportunity to selectively examine factors leading to apoptosis in the ischemic heart under controlled experimental conditions.     

Trends in Temperature Extremes in Association with Weather-Intraseasonal Fluctuations in Eastern China

Trends in the frequencies of four temperature extremes (the occurrence of warm days, cold days, warm nights and cold nights) with respect to a modulated annual cycle (MAC), and those associated exclusively with weather-intraseasonal fluctuations (WIF) in eastern China were investigated based on an updated homogenized daily maximum and minimum temperature dataset for 1960-2008. The Ensemble Empirical Mode Decomposition (EEMD) method was used to isolate the WIF, MAC, and longer-term components from the temperature series. The annual, winter and summer occurrences of warm (cold) nights were found to have increased (decreased) significantly almost everywhere, while those of warm (cold) days have increased (decreased) in northern China (north of 40°N). However, the four temperature extremes associated exclusively with WIF for winter have decreased almost everywhere, while those for summer have decreased in the north but increased in the south. These characteristics agree with changes in the amplitude of WIF. In particular, winter WIF of maximum temperature tended to weaken almost everywhere, especially in eastern coastal areas (by 10%-20%); summer WIF tended to intensify in southern China by 10%-20%. It is notable that in northern China, the occurrence of warm days has increased, even where that associated with WIF has decreased significantly. This suggests that the recent increasing frequency of warm extremes is due to a considerable rise in the mean temperature level, which surpasses the effect of the weakening weather fluctuations in northern China.     

Epstein-Barr virus in malignancies in renal transplant recipients in Japan

A role for Epstein-Barr virus (EBV) in the development of malignancies including lymphomas, and carcinoma of the stomach, nasopharynx, thymus and salivary gland is suggested. It is indicated that EBV evokes polyclonal-B-cell-proliferative diseases in immunocompromised hosts, such as transplant patients, which results in monoclonal malignant lymphomas. The suppression of immune functions in these patients is thought to lead to incomplete elimination of the cells expressing EBV latent infection genes. To examine the etiological role of EBV in the development of malignancies following renal transplant in Japan, 42 malignancies in 1744 cases of renal transplant were studied for the presence and type of EBV. The polymerase chain reaction revealed that 5 malignancies were positive for EBV, all type A: 2 of 2 cases of non-Hodgkin's lymphoma (NHL), 2 of 8 cases of gastric adenocarcinoma of the common type, and 1 of 2 cases of gastric plasmacytoma. In situ hybridization revealed positive signals in the nucleus of tumor cells in 2 cases of NHL and 1 of plasmacytoma. Positive signals were found in the small lymphoid cells but not in the tumor cells in 2 cases of gastric carcinoma. On the basis of these findings, a role for EBV in the development of malignancies in renal transplant patients is unlikely except for lymphoid neoplasias.     

我国钨冶炼技术的新进展

综述了近年来我国钨冶炼在开发处理多种资源的工艺技术，钨钼分离技术，从低品位钨矿物原料和含钨废料中生产高纯APT，钨冶炼技术装备和自动化水平，膜分离技术在开发无污染钨冶炼工艺的应用，超细钨粉等方面的最新进展和成果。在此基础上，展望了我国今后钨冶炼发展的方向。     

Fractures in childhood in Khartoum

A prospective study of fractures in 231 children received at Khartoum North Teaching Hospital(KNTH) was carried out for a period of six months. The incidence of child fracture rated as one per day, then it increased from the age of 5 years onwards in boys and between 6 and 8 years in girls. Most injuries were sustained during the day time, especially between late afternoon and sunset. 82% of injured children presented to a medical facility, while 18% were taken to native healers first. Non-road traffic accidents accounted for 84% of the fractures mainly due to sports, domestic injuries and falls; whereas road traffic accidents were 16% and occurred mainly in pedestrians. Forty three percent of the fractures needed only first aid and splintage while 42% needed closed reduction. Thirty one percent of all patients were treated as inpatients. The long bones were affected in 91% of all fractures, the commonest site being the distal end of the forearm (26%), followed by supracondylar fracture of the humerus (15.6%). In the upper limb, left-sided fractures predominated. The epiphyseal injuries were 3.5% of all fractures, mainly at the distal radial epiphysis. Boys were commonly affected between 13-15 years of age. Open fractures constituted 9.8% of the series and were mainly due to traffic accidents in town dwellers, the most vulnerable bones were those of the leg and foot. Pathological fractures accounted for 2.2% and were due to bone cysts and osteogenesis imperfecta. The problem of child safety and the preventive measures need to be more stressed.     

The change in laser usage in gastroenterology--the status in 1997

Since the establishing of laser technology in gastroenterology there has been a change in the indications for laser therapy and numerous new laser systems have been introduced in basic and clinical research. First the argon laser and later on the Nd:YAG laser were used mainly for bleeding peptic lesions, today emphasis is on palliative desobliteration of advanced esophageal and rectosigmoidal carcinoma. Moreover, in selected cases it is used for curative ablation of early carcinoma and dysplasia. A new field of application is photocoagulation of the "watermelon stomach". Despite of promising ablation results the erbium:YAG and holmium:YAG laser became not yet established in gastroenterology. Also the KTP laser is rarely used e.g. for treatment of telangiectasia. Difficult bile duct stones can be highly effective fragmented intracorporally by means of laser lithotripsy; an automatic stone-tissue discrimination system avoids uncontrolled injury of the bile ducts. The hitherto experimental interstitial laser therapy of primary and secondary liver malignancies shows excellent results, but online monitoring of the expansion of the necrosis is still a problem. Thermal probes, MRT technology and duplex sonography are under current evaluation. Photodynamic therapy (PDT) is now, after numerous pilot studies, investigated with larger numbers of patients. First results show a marked effectiveness in ablation of dysplasia and mucosal carcinoma. The photosensitizer 5-aminolaevulinic acid seems to be particularly effective for ablation of Barrett's mucosa and m-THPC for treatment of local carcinoma. Palliative PDT of bile duct cancer may help to avoid repeated endoprosthetic treatment. The possibilities and limitations of light induced fluorescence diagnostics of severe dysplasia and carcinoma in situ is now being evaluated intensively. This method might in future facilitate the endoscopic diagnosis of dysplasia in Barrett's esophagus and chronic inflammatory bowel disease.     

风吹石墨在莱钢6m焦炉的应用

针对石墨在焦炉内的生成机理,对莱钢7号、8号焦炉炉墙上的石墨采用压缩空气进行吹扫,有效控制了石墨的生长速度,降低了劳动强度。     

Heatstroke in runners in Oklahoma

It is a common opinion that general surgery is the first step for whoever approaches a surgical discipline, and that whoever practices training in general surgery should learn the rudiments of each surgical branch. The role of microsurgery in the training of the general surgeon has not been well-established. Clinical applications of microsurgery in general surgery are few and are rarely required, and have been connected strictly to restricted indications. However, we think that microsurgery could be very useful to the general surgeon because it allows the execution of experimental research on rats, the only possibility permitted by law. In these studies the microsurgeon can perform many times and in a short time the same surgical operation, thus improving his skill, and easily getting familiarity with surgical instruments and sutures.