共查询到20条相似文献,搜索用时 78 毫秒
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Dr.‐Ing. Professor Ottmar Knacke Dr.‐Ing. Michael Lemperle Ursula Seidl 《国际钢铁研究》2000,71(6-7):189-196
In an ultra high vacuum heterogeneous gas reactions such as 2 C + O2G → 2 COG and C + CO2G → 2 COG often show a less complicated reaction path than under normal pressure. In the present study the graphite sample is a commercial light‐bulb filament, which is extremely resistant against oxidation. Under low pressure the combustion reaction is of first order with a continuous transition to zero order at temperatures between 900 and 1300 K depending on the oxygen pressure. The Boudouard reaction behaves similarly but obeys zero order only around 2000 K and for CO2 pressures around 1 bar. The measured and the statistically calculated reaction rates agree well. An insight of the details of the reaction and chemisorption is determined by the evaluation of experiments carried out in an ultra high vacuum using isotopes such as 13CO2G. The Boudouard equilibrium for graphite can be reached only catalytically, e.g., with sponge iron in statu nascendi. 相似文献
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H. Toyota M. Hasegawa S. Oh‐yama K. Wakimoto T. Ariyama M. Asanuma M. Iwase 《国际钢铁研究》2006,77(6):379-384
To better understand the thermodynamic behaviour of chlorine in blast furnaces, CaO‐SiO2‐Al2O3 slags were brought into equilibrium with Ar + H2 + HCl + H2O gas mixtures at temperatures between 1673 K and 1798 K. The dissolution of chlorine into molten slags could be well interpreted through a reaction: (1/2) {CaO}slag + (HCl) = {Ca1/2Cl}slag + (1/2) (H2O). Conforming to this formula, a linear relation was observed between log (%CI) and log with an anticipated slope of 1/2. 相似文献
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Antipyrineandsomeofitsderivativescanbeusedinsynergisticextractionoftherareearthions.Someoftheirrareearthcomplexesshowthelumin... 相似文献
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2,6-吡啶二甲酸钠与三氯化镓在pH≈3的条件下直接反应,合成了NaGa(C7H3NO4)2·2H2O配合物单晶.通过元素分析、红外及X射线衍射分析确定了配合物的结构.以该配合物作为催化剂,用罗丹明B模拟染料废水进行了光催化降解脱色试验,对影响反应的各种条件(如催化剂的投加量,染料的初始浓度,通氧速率及光源)进行了考察.结果表明,在催化剂为20mg,染料初始浓度为2.0×10-4mol·L-1,通氧速率为200ml·min-1,光源为500W汞灯时,配合物NaGa(C7H3NO4)2·2H2O具有优良的催化活性,1h内对罗丹明B的降解率可达98.9%. 相似文献
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VZ Pletnev SN Ruzeinikov IN Tsigannik VT Ivanov SV Pletnev DA Langs WL Duax 《Canadian Metallurgical Quarterly》1997,42(6):651-658
The crystal and molecular structure of the valinomycin analogue, cyclo[(D-Val-L-Lac-L-Ala-D-Hyi)2(D-Val-L-Lac-L-Val-D-Hyi)] has been solved by x-ray direct methods using the "Shake and Bake" procedure. The crystals, grown from a mixture of octane/CH2Cl2, belong to space group P2(1) (Z = 4) with cell parameters a = 10.29, b = 32.08, c = 18.73 A, beta = 97.05 degrees, and contain two molecules per asymmetric unit. After anisotropic refinement the standard reliability factor was Rl = 0.058. The conformations of both independent molecules is similar to that observed for isoleucinomycin, cyclo[-(D-Ile-L-Lac-L-Ile-D-Hyi)3] [V. Z. Pletnev et al. (1980) Biopolymers, Vol. 19, pp. 1517-1534]. The structure has an asymmetric conformation stabilized by six intramolecular H bonds, five bonds being of the 4-->1 type and one bond being of the 5-->1 type. One water molecule is caged in the internal cavity of each cyclodepsipeptide. This conformation could represent an intermediate state between free and complexed forms of valinomycin. 相似文献
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Reactive oxygen species are known to cause attenuation of cardiac muscle contraction. This attenuation is usually preceded by transient augmentation of twitch amplitude as well as cytosolic Ca2+. The present study examines the role of an endogenous antioxidant, glutathione in the mechanism of H2O2-mediated augmentation of Ca2+ release from the sarcoplasmic reticulum. Whole-cell patch-clamped single rat ventricular myocytes were dialyzed with the Cs+-rich internal solution containing 200 microM fura-2 and 2 mM glutathione (reduced form). After equilibration of the myocyte with intracellular dialyzing solution, Ca2+ current-induced Ca2+ release from the sarcoplasmic reticulum was monitored. Rapid perfusion with H2O2 (100 microM or 1 mM) for 20 s inhibited Ca2+ current, but enhanced the intracellular Ca2+ transients for 3-4 min. Thus, the efficacy of Ca2+-induced Ca2+ release mechanism was augmented in 71% of myocytes (n = 7). This enhancement ranged between 1.5- to threefold as the concentrations of H2O2 were raised from 100 microM to 1 mM. If glutathione were excluded from the patch pipette or replaced with glutathione disulfide, the enhancement of Ca2+-induced Ca2+ release was seen in only a minority (20%) of the myocytes. H2O2 exposure did not increase the basal intracellular Ca2+ levels, suggesting that the mechanism of H2O2 action was not mediated by inhibition of the sarcoplasmic reticulum Ca2+ uptake or activation of passive Ca2+ leak pathway. H2O2-mediated stimulation of Ca2+-induced Ca2+ release was also observed in myocytes dialyzed with dithiothreitol (0.5 mM). Therefore, reduced thiols support the action of H2O2 to enhance the efficacy of Ca2+-induced Ca2+ release, suggesting that redox reactions might regulate Ca2+ channel-gated Ca2+ release by the ryanodine receptor. 相似文献
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V. N. MISRA 《Mineral Processing and Extractive Metallurgy Review》2013,34(1-4):223-232
Abstract A multimetallic sulphide concentrate containing sphalerite, galena, chalcopyrite and silver in the matrix of pyrite was decomposed at elevated temperature and oxygen pressures in dilute sulphuric acid solutions for sufficient residence time to yield 95% of the zinc in the pregnant solution while most of the lead and silver remained in the residue together with most of the pyrite. The selective leaching process appeared to follow the diffusion controlled mechanism. The effects of concentration of the leachant, temperature and time of leaching, particle size, oxygen pressure and agitation on the leaching process were investigated. Results indicate the prospect of extracting not only all the metals but also appreciable amounts of elemental sulphur under optimized experimental conditions. 相似文献
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M. Loudjani J. C. Pivin C. Roques-carmes P. Lacombe J. H. Davidson 《Metallurgical and Materials Transactions A》1982,13(7):1299-1311
A series of Fe-Ni-Cr, Fe-Cr-AI, and Fe-Ni-Cr-Al alloys has been exposed at 1200 °C in atmospheres of controlled oxygen and
sulfur potentials, after preoxidation in air or in impure argon. The corrosion behavior has been interpreted on the basis
of phase-stability diagrams. The presence of iron and nickel-rich spinel particles in the outer layers of the initial oxide
scales plays an essential role in the resistance to sulfur attack. When the oxygen potential is sufficiently low, these spinels
are reduced to a mixture of chromium oxide and an Fe-Ni alloy. The latter can then form sulfides which are liquid at high
temperatures and which accelerate the penetration of sulfur into the underlying metal.
C. ROQUES-CARMES, formerly at the Laboratoire de Métallurgie Physique, Orsay. 相似文献
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The chemical potential of O for the coexistence of Ni + NiO and Ni + Cr2O3 + NiCr2O4 equilibria has been measured employing solid-state galvanic cells, (+) Pt, Cu + Cu2O // (Y2O3)ZrO2 // Ni + NiO, Pt (-) and (+) Pt, Ni + NiO // (Y2O3)ZrO2 // Ni + Cr2O3 + NiCr2O4, Pt (-) in the temperature range of 800 to 1300 K and 1100 to 1460 K, respectively. The electromotive force (emf) of both
the cells was reversible, reproducible on thermal cycling, and varied linearly with temperature. For the coexistence of the
two-phase mixture of Ni + NiO, δΜO
2(Ni + NiO) = −470,768 + 171.77T (±20) J mol−1 (800 ≤T ≤ 1300 K) and for the coexistence of Ni + Cr2O3 + NiCr2O4, δΜO
2(Ni + Cr2O3 + NiCr2O4) = −523,190 + 191.07T (±100) J mol−1 (1100≤ T≤ 1460 K) The “third-law” analysis of the present results for Ni + NiO gives the value of ‡H
298
o
= -239.8 (±0.05) kJ mol−1, which is independent of temperature, for the formation of one mole of NiO from its elements. This is in excellent agreement
with the calorimetric enthalpy of formation of NiO reported in the literature. 相似文献