半球点测试仪研制

采用高精度欧陆3508/3504温度控制器,计算机RS232串口通讯技术和CCD成像技术,研制了半球点测试仪,其测试误差小于3℃,可满足对冶金辅料检测的快速准确检测精度的要求。     

欧陆590与组态王的通讯

本文介绍了欧陆590的通讯协约和组态王的通讯设备以及欧陆590与组态王的通讯实例。     

直流调速系统在机床中的应用

介绍欧陆590P数字直流调速器典型功能块的控制原理，以及在重八米卧车改造中的应用。功能块的运用代替了原控制电路的功能，减少了外围的配置和接线；提高了系统的准确性和稳定性；方便了设备的维护和故障处理。     

关于冰箱温控器调节的探讨

随着我国经济的发展和人民生活水平的提高,电冰箱已成为常用的家用电器.冰箱是比较复杂的机电一体化的产品,尽管良好的生产工艺及先进技术的应用已使电冰箱变得相当可靠、相当耐用,但如果不合理调节冰箱温控器,就造成电能的浪费和冰箱寿命的缩短.所以正确调节冰箱温控器档位非常重要.     

新一代控制单元在高炉煤气锅炉控制上成功运用

介绍了分散控制系统在高炉煤气热电厂的应用情况,包括采用英国欧陆NETWORK-6000+系统配置状况、特点及应用效果等。     

龙门锯切机列的节能技术改造

本文介绍了PLC、欧陆590全数字直流调速装置在龙门锯切机列中的应用,分析了系统改造控制方案和软硬件结构的设计,最后阐述了电气传动系统改造后的的优点和节能效果.     

宇电大屏系列 重新定义智能温控器——访宇电自动化项目负责人粟晓立

<正>仪器仪表行业的重量级展会——多国仪器仪表展将于9月22日在重庆拉开帷幕,众多仪器仪表的企业摩拳擦掌,准备拿出最好的状态和产品呈现在新老客户面前。本刊记者得知,在本届的多国仪器仪表展上,温控器龙头企业宇电自动化(以下简称"宇电")将给我们带来其强势推出的新品——宇电大屏系列触摸操作记录型人工智能温度控制器(以下简称"宇电大屏系列"),这一系列产品与传统温控器相比究竟有     

基于欧陆温控仪2604和工控机的温度监控系统的通信问题

用定向凝固法提纯铝的关键是精确灵活控制熔体温度场,本文就高纯铝提纯系统的温度监控子系统进行了介绍,重点讨论了子系统中工控机与欧陆温控仪2604间的通信问题.     

可逆热轧机控制系统的应用实践

本文阐述了由欧陆590全数字直流调速装置、S7-300可编程序控制器、WinCC组态软件以及ProfibusDP构成的(φ)900可逆热轧机控制系统,介绍了系统的软硬件设计及WinCC和Profibus DP在轧机控制系统上的应用.     

Profibus控制技术在拉伸弯曲矫直机组中的应用

介绍了拉伸弯曲矫直机组自控系统原理及硬件配置,阐述了Profibus总线网络结构特点--由PLC、触摸屏、现场I/O模块、欧陆590+直流驱动器组成、是一种开放的、模块化的、实时多任务的、集散型的、可扩展的数据采集和自动控制系统.     

太钢六轧厂2300mm轧机电气系统改造的设计与应用

简要介绍了太钢六轧厂2300mm轧机电气系统改造工程的主传动、液压系统、辅助传动系统、自动化系统的改造内容以及基本控制功能。主传动采用西门子SIMADYND系统取代旧系统,辅助传动系统采用西门子6RA70系列和欧陆590+系列直流调速器,自动化系统采用S7-300型PLC。系统设计先进,可靠性好,在冶金行业内具有很好的参考价值。     

Incidence of the prozone phenomenon in syphilis serology

OBJECTIVE: To determine the rate of the prozone phenomenon in our patient population. METHODS: Sera from 4328 patients--3504 females (2065 pregnant, 1439 nonpregnant) and 824 males--were tested for syphilis by the rapid plasma reagin (RPR) test, and then rechecked with serial twofold dilutions of up to 16-fold to detect the prozone phenomenon. Chi-square analysis with Yates correction was used, with P < or = .05 considered significant. RESULTS: The total positivity rate in females was 6% (213 patients); 13% (27) of the positive tests were false-positive reactions as confirmed by a negative anti-treponemal antibody test. Only one prozone reaction was detected, in serum from a male subject, but it was not missed on initial screening. CONCLUSION: The rate of prozone phenomenon is very low (95% confidence interval 0-0.4%), and routine serial dilutions are not cost effective.     

The effect of lead selection on traditional and heart rate-adjusted ST segment analysis in the detection of coronary artery disease during exercise testing

1. The present studies were designed to measure the affinity of UP 269-6, a newly developed angiotensin AT1 receptor antagonist, for vascular AT1 receptors from normotensive and hypertensive rats and to investigate in vitro, its effects on angiotensin II (AII)-induced hyperplasia and hypertrophy of vascular smooth muscle cells (VSMC). In addition the in vivo effects of UP 269-6 on neointimal proliferation in a carotid artery balloon injury in normotensive rats were also investigated. 2. UP 269-6 selectively inhibited [125I]-Sar1-Ile8-AII binding to vascular AT1 receptors present on VSMC derived from normotensive Wistar rat and from SHR (Ki = 16.6 +/- 3.6 nM and 7.5 +/- 2.0 nM, respectively). In comparison, losartan and its metabolite, EXP 3174, inhibited [125I]-Sar1-Ile8-AII binding to vascular AT1 receptors derived from both cell models with Ki values slightly lower (losartan) and higher (EXP 3174), respectively, than that of UP 269-6. 3. AII (1 microM) induced a weak and variable hyperplastic response (4 to 32% increase in cell number) in Wistar rat VSMC after 96 h. 4. AII (1 microM) induced a time-dependent increase in cell number in VSMC from SHR. UP 269-6 inhibited concentration-dependently this effect with an IC50 value of 159 +/- 58 nM. Losartan was clearly less potent and EXP 3174 showed nearly the same inhibitory potency, compared to UP 269-6. UP 269-6 (1 microM) inhibited nearly completely the action of AII. 5. AII (500 nM) caused maximal stimulation of protein synthesis in Wistar rat VSMC (117 +/- 36%). UP 269-6, losartan and EXP 3174 totally inhibited this stimulation with IC50 values of 28 +/- 6 nM, 3504 +/- 892 nM and 21 +/- 3 nM, respectively. 6. AII (50 nM) induced maximal stimulation of protein synthesis in SHR VSMC (237 +/- 67%). UP 269-6, losartan and EXP 3174 totally inhibited this stimulation with IC50 values of 16 +/- 3 nM, 282 +/- 122 nM and 3.3 +/- 1.0 nM, respectively. 7. UP 269-6 (75 mg kg-1 day-1) administered orally in the diet for 20 days induced a 38% reduction in neointimal area and a 36% reduction in neointima/media ratio associated with the intimal thickening induced by carotid artery balloon injury. 8. In conclusion, UP 269-6 was shown to be a potent antiproliferative agent both in vitro on AII-induced hyperplasia and hypertrophy of VSMC derived from normotensive and hypertensive rats, and in vivo upon intimal thickening induced by carotid artery balloon injury in the rat.     

Completion pneumonectomy: analysis of operative mortality and survival

BACKGROUND: A single-institution experience with completion pneumonectomy was analyzed to assess operative mortality and late outcome. METHODS: A consecutive series of 138 completion pneumonectomies from 1975 to 1995 was reviewed, and compared with single-stage pneumonectomies performed during the same period. RESULTS: Hospital mortality was 13.8%, including 4 intraoperative and 15 postoperative deaths. Hospital mortality was the same for lung cancer (13.2%) as for benign disease (15.5%). It was 37.5% if an early complication of the primary operation was the indication (p = 0.01). If infection of the pleural space was the indication for completion pneumonectomy, hospital mortality was 23.3% (p > 0.05). In 760 single-stage pneumonectomies hospital mortality was 8.7% (p > 0.05). Five-year actuarial survival after completion pneumonectomy was 42.5% for all patients, 32.3% for those with lung cancer, and 58.8% for those with benign disease. CONCLUSIONS: Hospital mortality for completion pneumonectomy was the same for malignant as for benign indications. It was significantly higher if completion pneumonectomy was done for an early complication of the primary operation. Results at long term of lung cancer patients were the same for single-stage pneumonectomy and completion pneumonectomy.     

Relationship between hamstring strains and leg muscle strength. A follow-up study of collegiate track and field athletes

Between August 1988 and October 1992, 1,052 patients underwent 1,522 valve procedures in our institution. Their mean age was 32.69 years (range 1-90). The etiology was rheumatic in 724 (68.8%), congenital in 120 (11.4%), degenerative in 99 (9.4%), infective in 58 (5.5%) and ischemic in 17 (1.6%). The mean preoperative functional class (NYHA) was 2.95 and 780 (74.1%) were in sinus rhythm. Repair was possible in 885 (58.1%) valves. The rate of repair versus replacement was 94.5% for the tricuspid, 56.2% for the mitral and 43.6% for the aortic valve. The total hospital mortality was 4.18%. For isolated mitral surgery it was 2.94%, for isolated aortic 4.12% and for isolated tricuspid 15%. Double valve surgery carried a mortality of 3% and triple valve surgery 13%. Hospital mortality for isolated mitral and isolated aortic surgery was lower for repair than for replacement (1.5% vs. 5% and 0 vs. 6.8%). The follow-up was 94.65% complete. The total incidence of embolic events was 2.93% with an actuarial freedom at 48 months of 92.71 +/- 5.35% for repair, 88.22 +/- 6.26% for replacement and 90.31 +/- 5.65% for patients with repair and replacement. Late mortality was 4.5%. The actuarial survival excluding hospital deaths was 94.89 +/- 2.10% for repair, 86.84 +/- 2.84% for replacement and 91.33 +/- 2.73% for the mixed group. The reoperation rate was higher for repair (13%) than for replacement (0.1%). This rate was highest for the rheumatic mitral patients with an age below 20 years (25.2%).(ABSTRACT TRUNCATED AT 250 WORDS)     

X射线荧光光谱法分析高碳铬镍生铁中7种元素

高碳铬镍生铁是不锈钢冶炼的前期产品,该钢中C、Si、Cr、Ni含量高,高含量元素间的谱线干扰给样品分析的准确度带来较大影响,提高该钢中主元素分析的准确度是降低不锈钢冶炼成本的关键。实验通过铣床参数的组合优化,确定了样品表面制备的最佳参数。通过X射线荧光光谱法分析条件的优化,确定了在40 kV电压和70 mA电流下,Si、Cr、Ni使用固定道分析谱线,C、Mn、P、S使用Kα1,2扫描道分析谱线;C使用AX16C晶体,Si使用InSb晶体,P和S使用Ge111晶体,Mn、Cr、Ni使用LiF200晶体;同时C使用2.60°超粗准直器,其他元素使用0.25°中粗准直器;在4~6 s时间内进行分析的试验条件。使用标准样品对C、Ni采用浓度乘法校正,对Si采用强度加法校正,对S采用浓度加法校正,对Mn、P、Cr采用强度乘法校正,绘制了C、Si、Mn、P、S、Cr、Ni 7个主元素的分析曲线,各曲线回归的相关系数在0.996 7~0.999 9之间。对实验方法进行了长期和短期精密度验证,分析结果的相对标准偏差(RSD,n=11)在0.019%～2.0%之间。正确度试验显示:样品的分析结果与参考值吻合较好。对日常分析中,时常出现的手指接触分析面,或是在样品表面被污染时用乙醇清洁的情况进行了试验比对,给出只有在不关注C元素分析结果时,才能对样品表面进行乙醇清洁处理。实验方法用于高碳铬镍生铁的分析可提高准确度,降低不锈钢冶炼成本。     

Purification and initial characterization of the ATP:corrinoid adenosyltransferase encoded by the cobA gene of Salmonella typhimurium

The cobA gene of Salmonella typhimurium and its product were overexpressed to approximately 20% of the total cell protein. CobA was purified to 98% homogeneity; N-terminal sequence analysis (21 residues) of homogeneous protein confirmed the predicted amino acid sequence. ATP:corrinoid adenosyltransferase activity was demonstrated in vitro to be associated with CobA. This activity was optimal at pH 8 and 37 degrees C. A quantitative preference was determined for Mn(II) cations and ATP. The apparent Km of CobA for ATP was 2.8 microM, and that for cob(I)alamin was 5.2 microM. Vmax was measured at 0.43 nmol/min. Cobinamide served as the substrate for CobA to yield adenosylcobinamide. Activity was stable at 4 degrees C for several weeks but was lost rapidly at room temperature (50% overnight). Dithiothreitol was required to maintain the enzymatic activity of CobA.     

Amphetamines in hair by enzyme-linked immunosorbent assay

Human hair was collected from the occipital crown region of the head from several subjects; these hair samples were presumptively positive for amphetamines by a previously evaluated immunoassay. Hair was washed briefly with methanol to remove external contamination, then extracted with hot methanol for 2 h to recover the drugs. The extracts were evaporated to dryness, reconstituted in buffer, and analyzed using a new enzyme-linked immunosorbent assay (ELISA) technique adapted for the detection of amphetamines in hair. Gas chromatography-mass spectrometry was used as the reference technique. Cross-reactivity of several related compounds was evaluated by equating the inverse of the ligand concentration at 50% antibody binding to the affinity constant for each compound. The ratio of a compound's affinity constant to that for d-methamphetamine was used to derive percent crossreactivity. These experiments yielded values of 30.8% for d-amphetamine, 7.4% for I-methamphetamine, 4.3% for phentermine, 2.9% for I-amphetamine, and <1% for ephedrine, methylenedioxyamphetamine, and methylenedioxymethamphetamine. Cross-reactivity of unrelated compounds was found to be non-existent. The optimum cutoff concentration was determined by receiver operating characteristic curve analysis to be 300 pg/mg and the observed limit of detection was 60 pg/mg. Intra-assay precision at 300 pg/mg was 3.3% (coefficient of variation, CV), and the interassay CV was 10.5%. The sensitivity and specificity of the method were 83% and 92%, respectively.