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51.
A combined method for determination of the standard enthalpies of formation of nitroform and its salts was proposed. The enthalpies
of dissolution of nitroform and its ammonium, hydrazinium, guanidinium, and potassium salts in water were measured. The enthalpy
of combustion of hydrazinium salt of nitroform was determined by a combustion calorimetry, and its standard enthalpy of formation
was calculated. The enthalpy of formation of trinitromethyl anion in indefinitely diluted aqueous solution −24.94±0.79 kJ
mol−1, was calculated on the basic of the data obtained for enthalpies of formation and dissolution of ammonium and hydrazinium
salts of nitroform. Standard enthalpies of formation of nitroform and its salts were calculated.
Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 12, pp. 2451–2454, December, 1998. 相似文献
52.
合成了乙二胺盐酸盐, 并表征了其晶体结构. 测定了其在78~370 K温度区间的低温热容, 通过最小二乘法拟合得到热容对温度的多项式方程. 设计了合理的热化学循环, 测定了所设计反应的反应物和产物的溶解焓, 得到反应焓. 利用Hess定律计算出乙二胺盐酸盐的标准摩尔生成焓为-(540.74±1.33) kJ/mol. 利用紫外-可见光谱和折光指数的结果检验了所设计热化学循环的可靠性. 相似文献
53.
Crystalline zinc silicate, Zn2SiO4, and zinc ferrite, ZnFe2O4, were prepared and characterized. The solubilities of these phases were measured using flow-through apparatus from 50 to
350 °C in 100 °C intervals over a wide range of pH. Both solid phases dissolve incongruently, presumably to form ZnO(s) and
Fe2O3(s) (or the corresponding hydroxide phases at low temperature), respectively. The respective concentrations of zinc(II) and
iron(III) matched those of ZnO(cr) and Fe2O3(s) (≥150 °C) reported in the literature, whereas the corresponding Si(IV) and Zn(II) concentrations were at least an order
of magnitude below the solubility limits for their pure oxide phases. Therefore, the solubility constants for zinc silicate
and ferrite were determined with respect to the known solubility constants for ZnO(cr) and Fe2O3(s) (≥150 °C), respectively, and the corresponding concentrations of Si(IV) and Zn(II) measured in this study. The results
of independent experiments, as well as those reported in the literature provide insights into the mechanism(s) of formation
of zinc silicate and ferrite in the primary circuits of nuclear reactors.
D.A. Palmer is retired. 相似文献
54.
R. M. Lazorenko-Manevich A. N. Podobaev L. A. Sokolova 《Russian Journal of Electrochemistry》2007,43(1):42-50
Based on the model of spatial separation of the dissolution and passivation of hydrophilic metals, the effect of strong specific adsorption of anions on the shape of curves for the relaxation of anodic current of metals in acid solutions after switching an anodic activation pulse off is considered by using iron as an example. 相似文献
55.
Giampiero Bettinetti Milena Sorrenti Laura Catenacci Franca Ferrari Silvia Rossi Ilaria Salvadeo Paolo Carraro 《Journal of inclusion phenomena and macrocyclic chemistry》2007,57(1-4):329-332
Triacetyl α-cyclodextrin, triacetyl β-cyclodextrin and triacetyl γ-cyclodextrin were tested as possible hydrophobic carriers
to prolong the release of hydrophilic teicoplanin (TCP). Physical–chemical characterization of individual components, drug-carrier
physical mixtures at 0.5, 0.67 and 0.75 mass fraction of carrier, and the respective interaction products by kneading or evaporative
crystallization under microwave irradiation was carried out using differential scanning calorimetry (DSC) and thermogravimetric
analysis (TGA). In vitro drug release in pH 7.4 phosphate buffer at 37 °C was determined by intrinsic dissolution rate (IDR)
measurements on non disintegrating compressed discs. Solid-state interactions of TCP with triacetyl α-cyclodextrin by evaporative
crystallization and kneading and with triacetyl β-cyclodextrin by evaporative crystallization (probably resulting in carrier
amorphization) were demonstrated. The role of carrier hydrophobicity, carrier mass fraction and preparation method of solid
drug-carrier combinations on solid-state drug-carrier interactions and slowing down of TCP release was assessed. Modulation
of drug release can be achieved using TCP-triacetyl γ-cyclodextrin combinations at 0.5 mass fraction of carrier. 相似文献
56.
57.
沉淀溶解法制备纳米硫化锌 总被引:7,自引:0,他引:7
以烷基黄原酸锌和硫化钠分别为锌源和硫源,采用烷基黄原酸锌沉淀溶解法制备了粒度可调、粒径分布比较窄的面心硫化锌纳米粒子,利用比表面积(BET)测定、透射电镜(TEM)、粉末X射线衍射(XRD)、傅里叶转换红外光谱(FTIR)等方法对合成的硫化锌纳米粒子进行了表征。结果表明随着烷基黄原酸锌链长的增长,通过添加硫化钠而生成的硫化锌纳米粒子的粒径逐渐减小。本文还对沉淀溶解法制备纳米硫化锌的溶液化学反应机理进行了探讨。 相似文献
58.
光纤药物原位溶出度/释放度监测仪实时监测复方氯唑沙宗片体外溶出度 总被引:1,自引:0,他引:1
研制了光纤-光学传感-药物溶出监测仪并应用于复方氯唑沙宗片的实时-原位体外溶出度.分支光纤的一端与光源相接,另一端与检测器连接,其公共端部探头浸入于盛于溶出杯中的溶解液中.借联机的计算机进行数据记录及处理,对复方氯唑沙宗片的组分对乙酰氨基酚和氯唑沙宗的回收率在低、中、高三个浓度水平进行了试验,结果依次为98.3%,102.3%和103.1%及108.6%,98.7%和97.7%,其相应的RSD值为1.0%,1.4%和0.4%及1.7%,1.6%及1.3%.应用此监测仪对药片的溶出全过程进行了监控,并显示了药物的溶解曲线,相关的溶出参数可随时提取.试验证明,使用该仪器可获得药物溶出全过程的真实情况的信息. 相似文献
59.
60.
[MnIIxFeII1?x(H2O)6][LiFeIII(ox)3] (with 0 ≤ x ≤ 1) crystallizes in the space group P31c with a = 9.341(3) Å, c = 10.226(3) Å, c/a = 1.0947, and V = 772.8(5) Å3 for Z = 2. The compound has a layered structure with two enantiomeric layers per unit cell. The layers are built up by an iron and lithium oxalate framework with intercalated M(II)-water octahedra of the formula [MnIIxFeII1?x(H2O)6][MIMIII(ox)3]. The value of x cannot be specified at present. The structure displays intermolecular hydrogen bonding between the layers. 相似文献