Advanced Materials Research Vols. 554-556

Abstract: Scanning electron microscopy (SEM), X-ray power diffraction (XRD) and Zeta potential () analyzer were used to investigate the changes of morphology, species, crystal quantity, , and aggregation state of urinary crystallites of calcium oxalate (CaO_xa) stone formers before and after taking drug potassium citrate (K₃cit). Before taking K₃cit the edges and corners of urinary crystallite were sharp and aggregated significantly, the main components were uric acid, calcium oxalate monohydrate (COM) and phosphate, etc. While after taking K₃cit for one week, some of urinary crystallites became blunt, the aggregated crystallites and the species of crystallites were obviously reduced, the amount of uric acid was reduced, but the percentage of calcium oxalate dihydrate (COD) and the absolute value of increased. Especially crystal depressions emerged at the surface of some crystallites, which was the direct proof of K₃cit dissolving CaO_xa stones in vivo. From the point of coordination between K₃cit and Ca²⁺, the increase of pH and citric acid concentration excreted in urine after taking K₃cit, the mechanism of how K₃cit inhibit the formation of COM stones was discussed.

Abstract: In order to obtain optimized operating condition for industry naphthalene purification using fractional crystallizing method, the influence of heating rate, crystallizing times, holding time and cooling rate on the yield and purity of industrial naphthalene were studied. The industrial naphthalene from AISC Chemical General tar workshop was used as starting material in the study. The results show that the yield and purity of refined naphthalene can achieve 94.2％ and 99.30％ respectively, when the heating rate is 1.2°C/h, the cooling rate is 3°C/h, holding time is 5 hours and the crystallizing times is 3. The result of present study provides a theoretical foundation for the actual production and technology improvement of naphthalene purification.

Abstract: Reaction 3-thiocyanatoacetylacetone with leucine (C6H13O2N1) was found to give 3-(5-acetyl-2-aminothiazol-4-ylthio)-4-hydroxypentan-2-one (I). Compound I crystallized in the orthorhombic system with space group Pbca a= 8.143 Å, b=13.831Å, c=21.878Å. V= 2463.7Å3, Z=8.

Abstract: With gallic acid and n-butanol as main materials, a new dendrimer micromolecular compound with the skeleton of gallic acid was synthesized by reactions of esterification and etherification of gallic acid. The structure of product was detected by elemental analysis, ¹H NMR, IR and MS. The target molecule has the structure of alkyl ester and phenoether. The differential scanning calorimeter (DSC) and polarizing optical microscope (POM) measurements showed the target molecular behavior of mesophase and its streak textures belong to nematic. Its temperature range of mesophase was 78 °C during heating process and 58 °C during cooling process. The results showed that dendrimer molecule can formed with the structural unit of gallic acid and it has lower melting point and behaviors of thermotropic liquid crystal.

Abstract: The supramolecular structure of 1,5-diaminotetrazole was investigated by first principles calculations, based on the plane-wave psedopotential method. The exchange-correlations potential was performed with the Perdew-Burke-Ernzerhof (PBE) functional of generalized gradient approximation (GGA). The Muliken population, total electron density and electron density difference were calculated. As a result, there are strong intramolecular and intermolecular hydrogen bonds among 1,5-diaminotetrazole molecules. The mainly reason for the formation of supramolecular structure of 1,5-diaminotetrazole is that the intermolecular hydrogen bonds of N(5)－H(5B)…N(4) and N(6)－H(6)…N(2).Moreover, chemical bond analysis showed that there are strong non-bond actions and the N(1)－N(5) bond seriously distorted was observed. The performance of 1,5-diaminotetrazole is quite related with the supramolecular structure.

Abstract: The morphological and optical properties of ZnO nanocrystals prepared by thermal evaporation of Zn powders were studied at both upstream and downstream under different O₂ flow rates. The morphological evolution was observed by scanning electron microscopy. With O₂ flow rates changing from 0.25 sccm to 1 sccm, the caps of the ZnO nanonails become bigger and the stems gradually disappear at upstream, and the diameters at the top of ZnO nanorods become thicker and the length become longer at downstream. Room temperature PL study shows that UV emission is relatively enhanced with increasing O₂ flow rates. Computational fluid dynamics simulation was performed, which indicates that the morphological evolution of the ZnO structures results from the competition between the axial growth and the radial growth based on different O₂ and Zn vapor partial pressure.

Abstract: Non-isothermal crystallization behavior of (Cu₆₀Zr₃₀Ti₁₀)₉₈Y₂ bulk metallic glass (BMG) has been investigated by Differential Scanning Calorimeter (DSC). The results show that crystallization in this bulk metallic glass has a three-stage crystalline precipitation process during continuous heating. The glass transition and crystallization behavior have relations to the continuous heating rate. Analyzed by the Kissinger and Ozawa method, apparent activation energies for three crystallization peak temperatures were Ep1

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