Synthesis and orientation study of a magnetically aligned liquid‐crystalline chitin/poly(acrylic acid) composite

A high magnetic field of 5 T was used to fabricate a magnetically aligned, optically anisotropic, liquid‐crystalline chitin/poly(acrylic acid) composite. The aligned mesophase was fixed by photoinitiated free‐radical polymerization. From an examination of polarized optical micrographs and an X‐ray diffraction study, a high degree of orientation of 0.70 was observed for the composite with a higher liquid‐crystalline chitin concentration (10.70 wt %); the orientation was reduced with a decreased chitin concentration at a given acrylic acid concentration. The X‐ray data for the developed composite showed a uniplanar orientation for the chitin crystallites, with its molecular long axes perpendicular to the direction of the magnetic field. © 2003 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 41: 711–714, 2003     

A facile non-oxidative method for synthesizing 1,3-disubstituted pyrroles from pyrrolidine and aldehydes

Reactions of pyrrolidine with 2 equiv of aldehydes without any catalyst in a pressurized vessel at 140–200 °C yielded 1,3-disubstituted pyrroles. -Branched aldehydes gave fairly good yields of the corresponding products by this method, which provides a facile non-oxidative procedure for synthesizing 1,3-dialkylpyrroles from inexpensive pyrrolidine and aldehydes.     

Study on effects of substrate temperature on growth and structure of alignment carbon nanotubes in plasma-enhanced hot filament chemical vapor deposition system

Alignment carbon nanotubes (ACNTs) were synthesized on silicon substrate coated with Ni catalyst film and Ta buffer layer by plasma-enhanced hot filament chemical vapor deposition using CH₄, NH₃, and H₂ as the reaction gas, and they were investigated by scanning electron microscopy and transmission electron microscopy. It is found that the diameter of the bamboo-structured ACNTs is increased from 62 to 177 nm when the substrate temperature was changed from 626 to 756 °C. Their growth rate is enhanced by the substrate temperature in a range of 626-683 °C and it is reversely reduced with the substrate temperature after the substrate temperature is over 683 °C. Beginning with wetting phenomenon, the effects of the substrate temperature on the structure and growth rate of the ACNTs are analyzed.     

XeF和KrF的热催化合成及KrF在含氟高能氧化剂NFBF合成中的应用

本文介绍了一种以氟气和惰性气体为原料合成 Kr F2 和 Xe F2 的热催化合成方法并对合成机理和条件作了简单的讨论 ,利用合成的 Kr F2 作为氟化剂合成了含氟高能氧化剂 NF4BF4,纯度约为 93%,其红外光谱和拉曼光谱基本与文献值吻合。元素分析结果表明产品 NF4BF4中含 B5.8%(mass) ,自由氟原子含量为 9.95%(mass) ,与理论值基本一致 ,此结果也间接证明了 Kr F2 质量的可靠性。粉末状的 Xe F2 经升华 -再结晶纯化后可得纯净晶体产品。     

Fast and continuous chemical isolation of short-lived isotopes of Hf,Ta and W as homologs of elements 104, 105 and 106

Some short-lived isotopes of Hf, Ta and W, synthesized at the U-400 cyclotron of JINR-Dubna, have been isolated using a previously elaborated fast continuous method of chemical isolation of element 104 from nuclear reaction products. The products were transported by a NaCl aerosol jet, from the irradiated targets to a separation device in which Hf, Ta and W were isolated by using three coupled ion-exchange columns.     

Synthesis of oxychelerythrine using lithiated toluamide-benzonitrile cycloaddition

Oxychelerythrine, benzo[c]phenanthridine alkaloid, was synthesized from easily available starting toluamide 5 and benzonitrile 6 using toluamide-benzonitrile cycloaddition reaction in 6 steps.     

A Novel Cu-Mo／ZSM-5 Catalyst for NOx Catalytic Reduction with Ammonia

The Cu-Mo/ZSM-5 catalysts with different Cu/Mo ratios were prepared by wet impregnation method, and their catalytic performance for selective catalytic reduction of NOx was studied. The results showed that Cu-Mo/ZSM-5 is a very effective catalyst for NOx catalytic reduction with ammonia, especially when Cu/Mo molar ratio is about 1.5. It not only exhibited the extremely high catalytic activity, but also showed good stability for 02. The bulk phase structure of Cu-Mo/ZSM-5 catalysts was determined by XRD technique, and the results indicated that there is a maximum dispersion for Cu species when Cu/Mo molar ratio is 1.5, and an interaction between Cu and Mo along with HZSM-5 may be present in Cu-Mo/ZSM-5, which may possibly result in a special structure favorable for the catalytic reduction of NOx over Cu-Mo/ZSM-5 catalyst.     

Durch Bromierung ausgelöste Umlagerung tertiärer Allylalkohole: Der Einfluss eines Fluor-Substituenten auf Reaktionsgeschwindigkeit und Reaktionsverlauf

Rearrangement of Tertiary Allyl Alcohols Induced by Bromination: The Effect of a Fluorine Substituent on the Rate and the Outcome of the Reaction The allyl alcohol bearing a methyl and a t-butyl group at the hydroxylated position was found to undergo a rearrangement when treated with bromine (or N-bromosuccinimide) in an aqueous medium and to afford a product mixture containing two regioisomeric ketones and one oxirane. Introduction of an additional methyl group or a fluorine atom at the non-terminal olefinic center led to a more selective discrimination between potential migratory groups. As the result of an exclusive t-butyl shift only one product, a ketone, was formed in both cases. Whereas the reaction rate was only slightly affected by the additional methyl group, it was substantially decreased by the fluorine atom.