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11.
Two hydrated uranyl arsenates and a uranyl phosphate were synthesized by hydrothermal methods in the presence of amine structure-directing agents and their structures determined: (N2C6H14)[(UO2)(AsO4)]2(H2O)3, DabcoUAs, {NH(C2H5)3}[(UO2)2(AsO4)(AsO3OH)], TriethUAs, and (N2C4H12)(UO2)[(UO2)(PO4)]4(H2O)2, PiperUP. Intensity data were collected at room temperature using MoKα X-radiation and a CCD-based area detector. The crystal structures were refined by full-matrix least-squares techniques on the basis of F2 to agreement indices (DabcoUAs, TriethUAs, PiperUP) wR2=5.6%, 8.3%, 7.2% for all data, and R1=2.9%, 3.3%, 4.0%, calculated for 1777, 5822, 9119 unique observed reflections (|Fo|?4σF), respectively. DabcoUAs is monoclinic, space group C2/m, Z=2, a=18.581(1), b=7.1897(4), c=7.1909(4) Å, β=102.886(1)°, V=936.43(9) Å3, Dcalc=3.50 g/cm3. TriethUAs is monoclinic, space group P21/n, Z=4, a=9.6359(4), b=18.4678(7), c=10.0708(4) Å, β=92.282(1)°, V=1790.7(1) Å3, Dcalc=3.41 g/cm3. PiperUP is monoclinic, space group Pn, Z=2, a=9.3278(4), b=15.5529(7), c=9.6474(5) Å, β=93.266(1)°, V=1397.3(1) Å3, Dcalc=4.41 g/cm3. The structure of DabcoUAs contains the autunite-type sheet formed by the sharing of vertices between uranyl square bipyramids and arsenate tetrahedra. The triethylenediammonium cations are located in the interlayer along with two H2O groups and are disordered. Both TriethUAs and PiperUP contain sheets formed of uranyl pentagonal bipyramids and tetrahedra (arsenate and phosphate, respectively) with the uranophane sheet-anion topology. In TriethUAs, triethlyammonium cations are located in the interlayer. In PiperUP, the sheets are connected by a uranyl pentagonal bipyramid that shares corners with phosphate tetrahedra of adjacent sheets, resulting in a framework with piperazinium cations and H2O groups in the cavities of the structure. 相似文献
12.
环丙沙星在胶束体系中的荧光特性研究及应用 总被引:9,自引:1,他引:8
研究了环丙沙星在胶束体系中的荧光性质,发现十二烷基硫基酸对环丙沙星有较强的增敏作用。据此建立了胶束增敏荧光光谱法测定痕量环丙沙星的新方法,经样品测定,其线性范围为0.033-0.60μg.mL^-1,检出限为0.033μg.mL^-1,回收率为94.0%-98.1%相对标准偏差为1.5%-2.8%。 相似文献
13.
A new flow electrical conductance instrument was constructed and tested on dilute NaCl solutions up to 458 K, and on more
concentrated solutions (maximum 0.436 mol⋅kg−1) at 373 K. The results of the new instrument agreed with those of previous authors within the estimated experimental errors.
The model of Bernard et al. (J. Phys. Chem. 96, 3833–3840 (1992), MSA) was found to represent the high-temperature results without introducing an ion-pairing equilibrium constant. The Fuoss–Hsia
conductance equation as given by Fernandez-Prini was found to represent the dilute concentrations with Λ° (NaCl) as the only adjustable parameter. It was found that Λ° (NaCl) could be expressed as a function of solvent viscosity and density by using three parameters found by regression of
literature results between 278.15 and 523 K. This equation along with the FHFP theory permits the equivalent conductivity
of dilute sodium chloride solutions to be calculated within the accuracy of the existing experimental measurements. 相似文献
14.
采用气相色谱-质谱(GC-MS)选择离子监测法(SIM),建立了准确可靠、灵敏度高、快速简便的测定维生素C泡腾片中甜蜜素含量的新方法.样品中的甜蜜素衍生后用有机试剂提取,在选择离子模式下进行测定,以保留时间和特征离子比例进行定性,单离子定量.甜蜜素的线性范围为0.05-10mg/L,检出限为0.6mg/kg,回收率为90.5%-96.9%,相对标准偏差小于4.4%.方法分析所用时间短,结果准确可靠,选择性好,适用于维生素C泡腾片中甜蜜素含量的检验. 相似文献
15.
Dilip H. Dagade Rajendra R. KumbharSandip R. Sabale Kesharsingh J. Patil 《Fluid Phase Equilibria》2007
In the present communication, we report the studies concerning liquid–liquid–solid equilibria for the ternary system sodium thiosulphate (Na2S2O3) + ethanol + water at ambient pressure and at room temperature (303 ± 2 K). The solubility data of Na2S2O3 are reported for solutions in water, ethanol and solutions of varying concentrations of ethanol in water. The phase diagram for the said system is developed, described and compared with similar system K2CO3 + methanol + water. These results have been explained in terms of structural properties of aqueous ethanol solutions and further discussed in terms of the effect of ions to cause phase separation. 相似文献
16.
比较了用三碘甲状腺氨酸抗体(T3抗体)、褐藻酸钠(AS)标记T3抗体及褐藻酸钠-纳米金复合物(ASN)标记的T3抗体,在通过免疫反应结合到免疫电极表面后,引起的电极表面微环境发生改变的程度;用Fe(CN)3-/4-6为电化学探针,用循环伏安法获取金电极表面微环境改变的电流信息来检测 T3抗体,检测的线性范围为100~1 600ng·ml-1,检出限为45ng·ml-1. 相似文献
17.
The study of the partitioning mechanism of methyl orange in an aqueous two-phase system 总被引:2,自引:0,他引:2
An aqueous two-phase system of dodecyl triethylammonium bromide (C12NE, cationic surfactant) and sodium dodecyl sulfate (SDS, anionic surfactant) mixture is proposed for the extraction of some dyes and porphyrin compounds. Transparent two phase-systems are formed when the surfactant concentrations and C12NE/SDS ratios are in certain regions. In this study, the aqueous two phase-systems were prepared by mixing 0.1 mol l−1 C12NE and SDS with a molar ratio of 1.7:1.0. The results showed that negatively charged chlorophyll (sodium copper chlorophyllin) and positively charged dye (methyl violet) were efficiently extracted into the upper phase. The negatively charged methyl orange (pH>7) was moved into the upper phase mostly while amphoteric methyl orange (pH<3) was distributed in the two phases uniformly. Except for hydrophobic force, charge interaction between solute and surfactant also play an important role in the extraction process. 相似文献
18.
19.
碲氢化钠是一个用途广泛的磁试剂,自作为有用的去溴试剂以来,日益受到化学工作者的关注,不断有文献报道它的合成及应用.例如能有效地还原卤代烃、硝基化合物、叠氮化合物和亚胺等.近年来,Katritzky报道了胺烷基化苯并三氮唑衍生物的合成及应用,此衍生物中的苯并三氮唑基是很好的离去基团,易被各种亲核试剂所取代.我们在前文中对硒氢化钠与胺烷基化苯并三氮唑反应生成二苄基二硒醚的合成进行了报道.本文用碲氢化钠与胺烷基化苯并三氮唑反应,结果生成还原产物N-取代胺. 相似文献
20.