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251.
Oxide to metal conversion is one of the most energy-intensive steps in the value chain for metals production. Solid oxide membrane (SOM) electrolysis process provides a general route for directly reducing various metal oxides to their respective metals, alloys, or intermetallics. Because of its lower energy use and ability to use inert anode resulting in zero carbon emission, SOM electrolysis process emerges as a promising technology that can replace the state-of-the-art metals production processes. In this paper, a careful study of the SOM electrolysis process using equivalent DC circuit modeling is performed and correlated to the experimental results. A discussion on relative importance of each resistive element in the circuit and on possible ways of lowering the rate-limiting resistive elements provides a generic guideline for designing optimum SOM electrolysis cells. 相似文献
252.
253.
在鼓泡吸收反应器中,以过硫酸盐溶液为氧化剂吸收脱除烟气中NO,以双膜理论为基础,研究了吸收过程中的传质动力学。对NO的氧化吸收过程进行了分析,建立了气液传质模型,测定了动力学参数:比相界面(a)和气相传质系数(KG)。结果显示:温度为75 oC,过硫酸盐溶液浓度在0.05-0.2M范围内,NO浓度≤1 000 ppm,NO的反应级数为0.5,过硫酸钠的反应级数为1,并确定了过硫酸盐溶液吸收NO总的传质速率方程。 相似文献
254.
为了提高氧化锌(ZnO)压敏电阻的电学性能,采用常规烧结并在ZnO压敏电阻中掺杂预先合成的BiSbO4和Zn2SiO4,研究不同掺杂比例对ZnO压敏电阻的微观结构、电学性能、通流能力的影响.结果表明:ZnO压敏电阻在掺杂BiSbO4和Zn2SiO4后,能够有效抑制ZnO晶粒变大,晶体结构变得致密均匀,致密性有所提高,有效提高压敏特性和通流能力.BiSbO4和Zn2SiO4掺杂比例为3∶1的样品综合性能比较优异,样品的致密度为5.58 g·cm-3,压敏电位梯度达到425 V·mm-1,非线性系数为70,漏电流为1.2×10-7 A·cm-2,能量耐受能力达到334.21 J·cm-3,残压比为2.5. 相似文献
255.
通过对锌蒸气冷凝过程的热力学分析 ,结合实际 ,从炉气、冷凝介质、冷凝设备来探讨如何提高火法炼锌的冷凝效率 相似文献
256.
Endothelium-derived nitric oxide and vascular physiology and pathology 总被引:13,自引:0,他引:13
J.-F. Arnal A.-T. Dinh-Xuan M. Pueyo B. Darblade J. Rami 《Cellular and molecular life sciences : CMLS》1999,55(8-9):1078-1087
In 1980, Furchgott and Zawadzki demonstrated that the relaxation of vascular smooth muscle cells in response to acetylcholine
is dependent on the anatomical integrity of the endothelium. Endothelium-derived relaxing factor was identified 7 years later
as the free radical gas nitric oxide (NO). In endothelium, the amino acid L-arginine is converted to L-citrulline and NO by
one of the three NO synthases, the endothelial isoform (eNOS). Shear stress and cell proliferation appear to be, quantitatively,
the two major regulatory factors of eNOS gene expression. However, eNOS seems to be mainly regulated by modulation of its
activity. Stimulation of specific receptors to various agonists (e.g., bradykinin, serotonin, adenosine, ADP/ATP, histamine,
thrombin) increases eNOS enzymatic activity at least in part through an increase in intracellular free Ca2+. However, the mechanical stimulus shear stress appears again to be the major stimulus of eNOS activity, although the precise
mechanisms activating the enzyme remain to be elucidated. Phosphorylation and subcellular translocation (from plasmalemmal
caveolae to the cytoskeleton or cytosol) are probably involved in these regulations. Although eNOS plays a major vasodilatory
role in the control of vasomotion, it has not so far been demonstrated that a defect in endothelial NO production could be
responsible for high blood pressure in humans. In contrast, a defect in endothelium-dependent vasodilation is known to be
promoted by several risk factors (e.g., smoking, diabetes, hypercholesterolemia) and is also the consequence of atheroma (fatty
streak infiltration of the neointima). Several mechanisms probably contribute to this decrease in NO bioavailability. Finally,
a defect in NO generation contributes to the pathophysiology of pulmonary hypertension. Elucidation of the mechanisms of eNOS
enzyme activity and NO bioavailability will contribute to our understanding the physiology of vasomotion and the pathophysiology
of endothelial dysfunction, and could provide insights for new therapies, particularly in hypertension and atherosclerosis. 相似文献
257.
B. Thébaud J.-F. Arnal J. C. Mercier A.-T. Dinh-Xuan 《Cellular and molecular life sciences : CMLS》1999,55(8-9):1103-1112
Inhaled nitric oxide (NO) is used to treat various cardiopulmonary disorders associated with pulmonary hypertension. The
rationale is based on the fact that NO, given by inhalation, only dilates those pulmonary vessels that perfuse well-ventilated
lung units. As a result, pulmonary gas exchange is improved while pulmonary vascular resistance is reduced and pulmonary blood
flow is increased. Inhaled NO has been succesfully applied to treat persistent pulmonary hypertension of the newborn, reducing
the need for extracorporeal life support. Although pulmonary hypertension and altered vasoreactivity contribute to profound
hypoxaemia in adult and paediatric acute respiratory distress syndrome (ARDS), the benefit of inhaled NO still remains to
be established in patients with ARDS. ARDS is a complex response of the lung to direct or indirect insults, leading to pulmonary
vasoconstriction and various inflammatory responses. Recent randomized trials suggest that inhaled NO only causes a transient
improvement in oxygenation. Whether this effect is important in the long-term management of ARDS remains to be established.
NO, measured in the exhaled breath, is an elegant and non-invasive means to monitor inflammation of the upper and lower respiratory
tract. In the normal upper airways, the bulk of exhaled NO originates from the paranasal sinuses. Exhaled NO is increased
in nasal allergy and decreased in cystic fibrosis, nasal polyposis and chronic sinusitis. That NO production is increased
in asthmatic airways is also well established. However, several questions still need to be addressed, in particular evaluation
of the sensitivity and specificity of the measurement techniques, and assessment of the bronchodilator action of endogenous
NO. 相似文献
258.
针对锌合金压铸时采用3Cr2W8V钢制作的模具使用寿命低的问题,通过试验分析了锌合金液对其的腐蚀原因.通过实验发现,若钢材中存在着大量的夹杂物和网状碳化物的缺陷,加上钢材本身存在的回火脆性问题,是导致钢材腐蚀的主要原因. 相似文献
259.
The effects of Cl-concentration,temperature,pH,flow velocity,soluble oxygen content of seawater and anodic current on the potential of high purity zinc and Zn-Al-Cd reference electrodes were investigated. The results show that the investigated metal materials are liable to establish stable potential and act as reference electrodes in seawater,diluted seawater and urban tap water. Cl-concentration,temperature,seawater flow velocity and anodic current have an obvious effect on zinc potentials. However,seawate... 相似文献
260.
研究了含亮铅锌矿经沸腾炉焙烧的挥发氧化物酸浸处理的浸渣的锌、铅分离,使用添加剂LHY后,常压下用硫酸浸取,在实验条件下,锌的浸取率达98%以上,而铅仍以硫酸铅的形式留在浸渣中,从而有效地将锌、铅分离,而其中稀有元素铟的浸出率也较高。 相似文献