Measurement of oxygen potentials in Ag-Pb system employing oxygen sensor

Accurate and instantaneous analysis of dissolved nonmetallic or metallic species in molten metals at elevated temperatures using an online electrochemical sensor is important for continuous process control during metal refining and alloying operations in metallurgical industries. In this article, the application of long-life, solid-state electrochemical sensors for oxygen has been demonstrated to measure the oxygen potential as a function of the lead concentration in a molten Ag-Pb system at 1323 K. Yttria-stabilized zirconia (YSZ) in the form of one end-closed tube 20 mm long, 3 mm inner diameter, and 1 mm wall thickness has been used as a solid electrolyte in the oxygen sensor. Electromotive force (EMF) of the solid-state electrochemical cell (−)Pt, Ni-NiO//YSZ//O _Ag-Pb, Mo(+) has been measured at 1323 K. The reference electrode consisted of Ni + NiO biphasic mixture; the working electrode was composed of a molten Ag-Pb alloy of varying concentrations of lead. The concentrations of lead in silver ranged from 0.02 to 10.20 wt pct. Samples of the molten alloy were drawn after each addition of Pb to Ag and analyzed by induction coupled plasma (ICP).     

Acute oxygen therapy

Tissues require oxygen for survival. Its delivery depends on adequate ventilation, gas exchange and distribution in the circulation. Many causes of hypoxaemia can be corrected by adding oxygen to the inspired air but response is variable and must be measured.     

Postoperative oxygen therapy

Much has been published in the medical literature concerning adverse events relating to the surgical patient. Among the notable disorders requiring the expertise of the postanesthesia care unit nurse are the diagnosis and management of respiratory dysfunction acutely attributable to the effects of surgery and anesthesia. Inhalational and/or intravenous anesthetic agents contribute to pathophysiological alterations that lend to the development of hypoxemia in the postoperative period. When patients present with preexisting respiratory disease, their care is frequently more complex and challenging. This review session will address the oxygenation component of respiration and the perioperative influences that alter it as well as treatment considerations for normalizing oxygenation.     

环氧温度对超音速主射流特性的影响

超音速氧气射流喷吹工艺是炼钢过程的重要技术,通过在主氧周围增加环状高温伴随流是改善主氧射流特性、提高冶炼效率的重要途径。通过数值模拟的方法研究集束射流条件下环氧温度对超音速氧气射流特性的影响。研究结果表明,高温环氧可抑制超音速主射流速度的衰减,环氧温度越高,速度衰减越慢,射流核心区长度明显延长;不同环氧温度下,主射流温度均呈现先增大后减小的趋势,环氧温度的升高使得主射流温度的快速增长受到抑制;环氧在主射流周围形成高温低密度区域,将主射流与环境介质隔离,延缓主射流与周围介质的掺混,对主射流起到封套作用。     

Capillary oxygen transport during severe hypoxia: role of hemoglobin oxygen affinity

The efficacy of an increased hemoglobin oxygen affinity [decreased oxygen half-saturation pressure of hemoglobin (P50)] on capillary oxygen transport was evaluated in the hamster retractor muscle under conditions of a severely limited oxygen supply resulting from the combined effects of a 40% reduction in systemic hematocrit and hypoxic ventilation (inspired oxygen fraction 0.1). Two groups of hamsters were utilized: one with a normal oxygen affinity (untreated; P50 = 26.1 +/- 2.4 Torr) and one with an increased oxygen affinity (treated; P50 = 15.7 +/- 1.4 Torr) induced by the chronic short-term administration of sodium cyanate. Using in vivo video microscopy and image analysis techniques, we determined oxygen saturation and associated hemodynamics at both ends of the capillary network. During hypoxic ventilation, the decrease in oxygen saturation across the network was 3.6% for untreated animals compared with 9.9% for treated animals. During hypoxia, estimated end-capillary PO2 was significantly higher in the untreated animals. These data indicate that, at the capillary level, a decreased P50 is advantageous for tissue oxygenation when oxygen supply is severely compromised, because normal oxygen losses in capillaries are maintained in treated but not in untreated animals. The data are consistent with the presence of a diffusion limitation for oxygen during severe hypoxia in animals with a normal hemoglobin oxygen affinity.     

高供氧压力下高马赫数氧枪数值模拟

  以北方某钢厂100 t转炉为原型，建立顶吹转炉炉内流场的三维数学模型，采用Fluent软件研究了不同高马赫数氧气射流与熔池钢液速度流场分布之间的依赖关系。研究发现，高马赫数氧枪在Ma（马赫数）为2.0～2.3时，曲线平稳，为最佳供氧压力。在提高供氧压力的同时，氧气射流的最大速度、熔池钢液面的冲击直径及冲击深度也随之增加。模拟结果显示，氧气射流在设计工况氧压小于1.0 MPa时，射流之间相互干扰作用最弱；氧气射流在设计工况氧压力大于1.0 MPa后，冲击直径与冲击深度增幅较小。基于上述研究，在实际生产中应用了高马赫数氧枪后，并结合变枪变压操作工艺，可以改善熔池底部钢液流动状况、稳定转炉吹炼过程、控制炉渣喷溅。     

Steroids and oxygen solubility

Determinations of oxygen solubility in serum were made utilizing various concentrations of corticosteroids in the serum. Within a certain concentration range dexamethasone and betamethasone caused an increase in oxygen solubility. None of the other steroids tested demonstrated this property.     

Long-term home oxygen therapy

Trichomonas vaginalis was diagnosed in 42 (19%) of 227 adult males with urethral discharge. In 27 men (15%) T. vaginalis was isolated together with Neisseria gonorrhoeae. Non-gonococcal urethritis was diagnosed in 15 patients and T. vaginalis was isolated from 47% of such patients. Stained smear preparations, i.e. RapiDiff and acridine orange of modified Diamond's media, were superior to wet smear microscopy for the identification of T. vaginalis. RapiDiff stain was the most sensitive and identified 41 of 42 (98%) positive cultures. It is recommended that all turbid culture media should be stained for the optimal diagnosis of trichomoniasis.     

转炉炼钢用氧枪快换装置和大锥度氧枪的应用

为了实现快速炼钢,降低工人的劳动强度,氧枪快换和大锥度氧枪的应用是炼钢厂发展的必然选择。文章详细介绍了氧枪快换和大锥度氧枪的结构、性能及特点,以及在鞍钢260t转炉实际使用的情况。     

变压吸附制氧过程中不连续反吹对回收率的影响

为了提高变压吸附制氧过程中氧气的回收率和体积分数,提出了一种在反吹步骤中采取适当中断次数和时间的不连续反吹方法,并实验研究了该方法对氧气的回收率和体积分数的影响.结果表明:不连续反吹步骤可以显著提高变压吸附制氧系统的回收率和产品气纯度;在本实验条件下,优化后反吹中断次数为2、反吹中断时间为0.3s时,与连续反吹相比,氧气回收率最大提高了9.2%,产品气中氧气的体积分数最大提高了4.0%.     

高炉休风时供氧管网压力对氧气调度的影响

以国内某大型钢铁企业空分厂为研究对象,基于混合整数线性规划方法建立以氧气放散量最小为目标的生产调度模型,并在此基础上以高炉休风期间的氧气生产调度为案例,分析了高炉开始休风期间管网初始压力对氧气放散率的影响.高压管网初始压力大于临界值时,系统出现氧气放散,放散率随初始压力上升呈近线性增大关系,高压管网缓冲容量越大,该线性关系斜率越大.有氧气放散的情况下,对于同一高压管网初始压力,高压管网缓冲容量越大,系统放散率越小.该趋势随着高压管网初始压力增大变得越来越不明显,当初始压力等于最高压力时,高压管网缓冲容量的大小对放散率没有影响.