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41.
络合滴定法测定钙含量微型实验研究 总被引:1,自引:0,他引:1
陈晓红 《广东微量元素科学》2006,13(9):64-66
利用微型滴定法测定含钙制品中的Ca2 含量,并对微型滴定法与常量滴定法的平行测定结果进行了比较。结果两种方法无显著性差异,F检验t检验结果均在允许范围内,相对偏差均小于2.0%,微型滴定法的精度达到常量滴定法测定水平,能满足化学分析要求。 相似文献
42.
L. A. Dunyushkina A. V. Kuz’min V. B. Balakireva V. P. Gorelov 《Russian Journal of Electrochemistry》2006,42(4):375-380
Transport numbers for oxygen ions and protons are measured by an emf method in the system CaTi1?x FexO3?δ (x = 0.1–0.5) in the oxidizing and reducing atmospheres in the temperature interval 973–1173 K. It is shown that the compounds under study are mixed ion-electron conductors at small iron concentrations and electron conductors, at large iron contents. The proton conductivity in the compounds is very poor and does not exceed 0.5% in air. On the basis of the temperature dependences of transport numbers for ions and linear expansion, it is established that the CaTi0.9Fe0.1O3?δ system has a phase transition of a second order in a reducing environment at 1020–1050 K. The total and partial electron conductivities of CaTi0.9Fe0.1O3?δ are studied as a function of the partial pressure of oxygen at 1173 K. The nature of electroconduction in CaTi1?x FexO3?δ is discussed. 相似文献
43.
Bi-Sr-Ca-Cu-O超导材料中存在110K和80K2个超导相。其组成是Bi_2Sr_2Ca_2Cu_3O_y和Bi_2Sr_2CaCu_2O。但迄今为止,在按2223组成比合成的未掺杂Bi系超导材料中从未得到过纯的110K相,也未见过组成为2223,零电阻温度在100K以上材料的报道。为了探索形成110K相的最佳条件,本文以2223组成比为参考,合成了5个系列材料:Bi_xSr_2Ca_2Cu_3O_y,Bi_2Sr_xCa_2Cu_3O_y,Bi_2Sr_2Ca_xCu_3O_y,Bi_2Sr_2Ca_2Cu_xO_y,Bi_i Sr_uCa_yCu_wO_s。 相似文献
44.
据报,在BiPbSrCaCuO中加Sb形成BiPbSbSrCaCuO体系的T_c可达130K。但其组成、结构、性质等均未见详细报道。我们合成了一系列BiPbSbSrCaCuO,发现了一个具有2212相结构、但T_c却为~110K的超导相。 试样制备包括将Bi_2O_3,PbO,Sb_2O_3,SrCO_3,CaO和CuO(AR级)混匀、碾磨、于 相似文献
45.
废弃生物质在超临界水中转化制氢过程的研究 总被引:14,自引:3,他引:14
以废弃生物质转化为富氢气体为目的,使用间歇式超临界水反应器,在反应温度773 K~923 K、压力15.5 MPa~34.5 MPa停留时间1 min~30 min和Ca/C摩尔比0~0.56范围内,对木屑在超临界水条件下生成的气体组成及产率进行了考察。实验表明,Ca/C摩尔比和温度对木屑转化的影响较大。当Ca/C摩尔比为0.48时,碳的气体转化率和氢气产率提高了近一倍。温度从773 K提高到923 K,碳的气体转化率由47%提高到76%,氢气产率由4.5 mmol/g上升到6.9 mmol/g。与温度相比,停留时间和压力的影响不大。 相似文献
46.
The absorption spectra of Co(II) chloride complexes, containing variable concentrations of chloride ligand, in a molten mixture of 80 mol% acetamide–20 mol% calcium nitrate tetrahydrate, were studied at 313, 333, 353, and 363 K, in the wavelength range 400-800 nm. The melt contains three possible ligands (CH3CONH2, H2O, and NO3
-) for competition with added chloride ligand. Addition of chloride caused a shift of the absorption maximum of octahedral cobalt(II) nitrate towards lower energies and pronounced changes in the shape of the initial spectrum of cobalt(II) nitrate. The effect of temperature changes on the molar absorption coefficient of the Co(II) species was dependent on the chloride concentration and was attributed to the structural changes occurring in the cobalt(II) species. The STAR and STAR FA programs were applied to identify the complex ionic species and to calculate the stability constants of Co(II) complexes formed in this solvent. The results indicate the highest probability of formation of the following complex species: Co(NO3)4
2-, Co(NO3)2Cl2
2-, and CoCl4
2-. Stability constants of each complex were presented for the equilibria occurring at 313, 333, 353, and 363 K. Distribution of the Co(II) species was also calculated over the ranges of chloride concentration and temperature investigated. 相似文献
47.
48.
Evaluation of the adsorption affinity of proteins to calcium hydroxyapatites by desorption and pre-adsorption methods 总被引:1,自引:0,他引:1
Kazuhiko Kandori Aya Fujiwara Megumi Mukai Akemi Yasukawa Tatsuo Ishikawa 《Colloids and surfaces. B, Biointerfaces》1998,11(6):313-320
The adsorption affinity of bovine serum albumin (BSA) and lysozyme (LSZ) to calcium hydroxyapatite (CaHAP) was evaluated by desorption and two step adsorption methods. These experiments were carried out at 15°C in a 1×10−4 mol dm−3 KCl solution of pH 6.0. BSA molecules were scarcely desorbed, exhibiting an irreversible adsorption of BSA, though LSZ slightly desorbed. This result supports our previous findings that LSZ adsorbs weakly onto phosphate ions exposed on ac or bc faces of CaHAP while BSA adsorbs strongly onto positively charged sites on ac or bc faces of CaHAP. The amount of adsorbed LSZ was markedly increased by the pre-adsorption of BSA, where LSZ was adsorbed onto BSA-covered CaHAP. On the other hand, the amount of adsorbed BSA was not changed by the pre-adsorption of LSZ. In both pre-adsorption systems it was confirmed by an HPLC method that no protein molecule pre-adsorbed was desorbed after the post-adsorption procedure. Therefore, it was interpreted that the enhancement of adsorption of positively charged LSZ is induced by an electrostatic attractive force through pre-adsorption of negatively charged BSA molecules with a high coverage. However, since the coverage of LSZ onto CaHAP is considerably low, no stimulation of BSA adsorption occurred on the LSZ-covered surface. The formation of double protein adsorbed layers consisting of pre- and post-adsorbed proteins was proposed. 相似文献
49.
50.
Surface modification of highly dispersed rubber fillers and pigments by titanate proadhesive and hydrophobic compounds 总被引:1,自引:0,他引:1
A method of modifying silicate and carbonate fillers with titanate coupling agents and proadhesive agents was worked out. The modification aimed at hydrophobization of filler surface by introduction to the surface of functional groups with chemical affinity to polymers. Optimum amounts of modifying substances and appropriate conditions for performing the modification process were established. The obtained fillers showed a high degree of hydrophobicity.The modified fillers were applied in rubber mixtures based on butadienestyrene or natural rubber, in polyurethanes, in PVC, and as pigments in oil dyes of high corossive resistance. 相似文献