Synthesis of SAPO-41 from a new reproducible route using H3PO3 as the phosphorus source and its application in hydroisomerization of n-decane

In the new reproducible route, phosphorous acid (H₃PO₃) or the mixture of H₃PO₃ and phosphoric acid (H₃PO₄) are used as the phosphorus source to synthesize microporous silicoaluminophosohates. It is found that gels containing H₃PO₃ favor the formation of SAPO-41 materials. With only H₃PO₃ as the phosphorus source, pure SAPO-41 phase can be prepared with high crystallinity. When the mixture of H₃PO₃ and H₃PO₄ is used as the phosphorus source, the crystallization of SAPO-41 can be accelerated. Raman and XRD results show that SAPO-41 can be formed after crystallizing for 12 h. The dosage of the template di-n-propylamine (DPA) can be reduced in the mixed phosphorus source system. The SAPO-41 has been used to prepare catalysts for the hydroisomerization of n-decane. High selectivity of isomerization (89.5%) has been observed even at high conversion (88%) over the Pt/SAPO-41.     

火花源质谱法定量分析高纯氧化钬和氧化镥中痕量元素

本文采用相对灵敏度因子，研究了９９．９９９％－９９．９９９９％的Ｈｏ２Ｏ３和Ｌｕ２Ｏ３中４０余种杂质元素的火花源定量分析方法，讨论了谱线干扰。做了加入回收及生理性实验，大多数元素的相对标准偏差在３０％以内，检测下限为０．００ｘμｇ／ｇ。     

Determination of radiation power of the solar-simulated light source

Calorimetric method for the determination of radiation power of the solar-simulated light sources has been proposed. The application of the differential scanning calorimetry guarantees very high sensitivity (1 mW) of the measuring property, independent of the wavelength (within 300-1200 nm). The applied method yields reliable calibration curves of the radiation power vs. wavelength with good accuracy. This revised version was published online in July 2006 with corrections to the Cover Date.     

Single Crystal X‐ray Diffraction Study of CsHSi2O5

Hydrothermally synthesized CsHSi₂O₅ was studied by single‐crystal X‐ray diffraction. The compound is orthorhombic (space group Pnma). Unit cell parameters are a = 4.9758(3), b = 8.8089(6), c = 12.9295(9) Å with four formula units per cell. The structure was solved by direct methods and refined to a residual R₁ = 0.025 for 621 independent observed reflections with I > 2σ(I) and 41 parameters. Residual electron densities were used to locate positions of the H atoms. They are part of silanol groups and show a disorder involving two positions related by a center of symmetry. The resulting O—H···O distance of 2.44 Å is one of the shortest hydrogen bonded O···O distances in inorganic compounds containing silanol groups. The structure belongs to the class of unbranched zweier double chain silicates. The [Si₂O₄(OH)^—] chains run parallel [100]. Cesium cations providing additional linkage between the anionic ribbons reside in voids between the chains and coordinate to nine oxygen ligands.     

Syntheses and structures of CsHo3Te5 and Cs3Tm11Te18 and the electronic structure of CsHo3Te5

Single crystals of CsHo₃Te₅ and Cs₃Tm₁₁Te₁₈ have been grown as byproducts in the synthesis of CsLnZnTe₃ (Ln=Ho or Tm) through the reaction of Ln, Zn, and Te with a CsCl flux at 850 °C. The crystal structures have been determined from single-crystal X-ray diffraction data. CsHo₃Te₅ crystallizes in space group Pnma of the orthorhombic system whereas Cs₃Tm₁₁Te₁₈ crystallizes in the space group C2/m of the monoclinic system. Each of the compounds adopts a three-dimensional structure; each possesses tunnels built from LnTe₆ octahedra that are filled with Cs atoms. The pseudo-rectangular tunnel in CsHo₃Te₅ is large enough in cross-section to accommodate two symmetrically equivalent Cs atoms. In the Cs₃Tm₁₁Te₁₈ structure there are two different sized tunnels: the smaller one is only large enough to host one Cs atom per unit cell whereas the larger one can accommodate two Cs atoms. The electronic structure of CsHo₃Te₅ was calculated. The band gap is estimated to be about 1.2 eV, consistent with the black color of the crystals.     

Electrocatalytic Processes in Lithium Power Sources

Most important electrocatalytic processes that occur in primary and secondary (rechargeable) lithium power sources are briefly considered.     

铷和铯含量的示波极谱滴定法测定

用了示波极谱滴定法测定硝酸盐样品中铷和铯的含量，回收率为９７７８％～１００３％，相对标准偏差均值为０２１％。该法以示波极谱图形突变来确定滴定终点，终点直观，不受溶液颜色、沉淀的影响，具有准、快、简、省的特点，有广泛的应用价值     

Low temperature synthesis of bilayer hydrated cesium cobalt oxide

Bilayer hydrated Na_0.35CoO₂·1.3H₂O structure has re-directed superconductivity research in recent years. Here, we develop a low temperature synthesis method to prepare a novel hydrous Cs_0.2CoO₂·0.63H₂O compound in one step. The bilayer-hydrate of Cs_0.2CoO₂·0.63H₂O with a greatest interlayer spacing d=10.0(2) Å among alkali cobalt oxides has been grown in crystal form. Magnetic susceptibility measurement of Cs_0.2CoO₂·0.63H₂O displays a paramagnetic behavior down to 1.9 K. With the assistance of low temperature molten CsOH solvent, crystals of Rb_0.30CoO₂·0.36H₂O and K_0.35CoO₂·0.4H₂O can be grown. The results provide the capability for preparing a novel hydrous structure and the systematic investigation of interlayer coupling effect of alkali ion insertion compounds.     

Nucleophilic aromatic substitution reaction of nitroarenes with alkyl- or arylthio groups in dimethyl sulfoxide by means of cesium carbonate

Treatment of nitroarenes having electron-withdrawing groups at the ortho or para position with alkanethiol in the presence of cesium carbonate in dimethyl sulfoxide at 25 °C leads to nucleophilic displacement of the nitro group with the alkylthio group. Cesium carbonate is superior to other bases such as potassium carbonate, sodium carbonate, and triethylamine. The cesium-mediated nucleophilic aromatic substitution reaction provides a mild yet powerful and user-friendly protocol for the synthesis of aryl sulfides.     

H nuclear magnetic resonance spectroscopy analysis for simultaneous determination of levodopa, carbidopa and methyldopa in human serum and pharmaceutical formulations

A method utilizing NMR spectroscopy has been developed to confirm the identity and quantity of levodopa, carbidopa and methyldopa in human serum and pharmaceutical preparations. The method is based on 500 MHz proton NMR spectra of individual catecholamine molecules. Qualitative and quantitative analyses are based on resonance characteristics of the functional groups present in their structures and the integral ratio of selected signals belonging to different compounds with respect to those of an internal standard, respectively. Experiments are performed to validate the quantitative NMR method, and the linearity and reproducibility of the proposed method are verified. The detection limit of the proposed method was estimated as 4.2, 1.7 and 1.6  μg ml⁻¹ for levodopa, carbidopa and methyldopa, respectively. The recovery studies performed on human serum samples ranged from about 82-96% with relative standard deviations of <4%. The method was also applied successfully to the determination of each active compound in real pharmaceutical samples, and compared with the results obtained by the reference methods. The method is rapid, precise, accurate, and suitable for routine analyses.