Coaxial electrospinning core-shell fibers for self-healing scratch on coatings

Polystyrene (PS) fibers with core-shell structure were prepared by coaxial electrostatic spinning using liquid epoxy or curing agent as the core and PS solution as the shell. Scratch self-healing coatings were realized by using the healant-loaded core-shell fibers in the matrix.     

Mg改性对Co/γ-Al2O3-TiO2催化燃烧丙烷性能影响

采用分步浸渍法制备了系列Mg改性的Co/γ-Al_2O_3-TiO_2催化剂,通过X射线衍射(XRD)、紫外可见漫反射光谱(DR-UV-vis)、N_2吸附-脱附(BET)、X射线光电子能谱(XPS)和H_2程序升温还原(H_2-TPR)等技术对催化剂进行表征,并考察了其对丙烷燃烧的催化性能。结果表明,Co在原始γ-Al_2O_3-TiO_2载体和Mg改性MgO/γ-Al_2O_3-TiO_2载体上均以Co_3O_4的形式存在;Mg掺入后与Al_2O_3作用形成MgAl_2O_4尖晶石,改善了载体的织构性质,提升了Co_3O_4在催化剂载体表面的暴露数量和分散程度。此外,MgAl_2O_4与Co_3O_4相互作用提升了Co_3O_4颗粒表面Co~(3+)/Co~(2+)和O_(ads)/O_(latt)的比例,并削弱了Co-O键键能,从而提升了其对丙烷的催化燃烧活性。当Mg负载量为15%(质量分数)时,在Co/MgO(15%)/γ-Al_2O_3-TiO_2催化剂上进行丙烷燃烧,丙烷90%转化率的温度比无Mg掺杂的Co/γ-Al_2O_3-TiO_2催化剂的降低了45℃,并且连续反应40 h其活性保持稳定。     

硅胶担载四核羰基钴催化剂的EXAFS和IR研究

本文以透射法EXAFS和IR等手段研究了四核羰基钴金属簇Co_4(CO)_(10)(PPh)_2担载在SiO_2上以后及用于烯烃醛化反应前后的变化,确定了相应的结构参数并探讨了催化活性与结构的关系。     

Pre-Column Derivatization of Amines with 1,2-Benzo-3,4-Dihydrocarbazole-9-Isopropyl Chloroformate Followed by LC-Fluorescence and LC-APCI-MS

A pre-column derivatization method for the sensitive determination of amines using the labeling reagent 1,2-benzo-3,4-dihydrocarbazole-9-isopropyl chloroformate (BCIC-Cl) followed by high-performance liquid chromatography with fluorescence detection has been developed. Identification of derivatives is carried out by high performance liquid chromatography/atmospheric pressure chemical ionization (LC-APCI-MS-MS). The chromophore of 2-(9-carbazole)-ethyl chloroformate (CEOC) reagent is replaced by 1,2-benzo-3,4-dihydrocarbazole-9-isopropyl functional group, which results in a sensitive fluorescence derivatizing reagent BCIC-Cl. BCIC-Cl can easily and quickly label amines. Derivatives are stable enough to be efficiently analyzed by high-performance liquid chromatography and show an intense protonated molecular ion corresponding m/z [MH]⁺ under APCI in positive-ion mode. The collision-induced dissociation of protonated molecular ion formed a product at m/z 260 corresponding to the cleavage of CH₂-OCO bond. Studies on derivatization demonstrate excellent derivative yields over the pH 9.0–10.0. Maximal yields close to 100% are observed with a 3 to 4-fold molar reagent excess. In addition, the detection responses for BCIC derivatives are compared with those obtained using CEOC and FMOC as derivatization reagents. The ratios of I_BCIC/I_CEOC and I_BCIC/I_FMOC are, respectively, 1.23–3.14 and 1.25–3.08 for fluorescent (FL) responses (here, I is relative fluorescence intensity). Separation of the derivatized amines had been optimized on reversed-phase Eclipse XDB-C₈ column. Detection limits are calculated from 1.0 pmol injection, at a signal-to-noise ratio of 3, are 10.6–37.8 fmol. The mean interday accuracy ranges from 94 to 105% for fluorescence detection with the largest mean %CV<7.5. The mean interday precision for all standards is < 6.0% of the expected concentration. Excellent linear responses are observed with coefficients of > 0.9997. Revised: 12 December 2005 and 13 Febrauary 2006     

A novel method of the separation/preconcentration and determination of trace molybdenum(VI) in water samples using microcrystalline triphenylmethane loaded with salicyl fluorone

It is the first time that triphenylmethane was used as an adsorbent to preconcentrate and separate trace amount of molybdenum in water samples. The effects of different parameters, such as acidity, stirring time and various metal ions, the amounts of triphenylmethane and salicyl fluorine, etc. on the enrichment yield of molybdenum have been studied to optimize the experimental conditions. Under the optimum conditions, molybdenum can be adsorbed on the surface of microcrystalline triphenylmethane loaded with salicyl fluorone by the intermolecular action strength. The possible reaction mechanism for the enrichment of molybdenum was discussed in detail in this paper. Mo(VI) can be completely separated from Pb(II), Co(II), Cu(II), Cr(III), Ni(II), Hg(II), Zn(II), Cd(II), Fe(III) and Al(III) in the solution. The proposed method was successfully applied to the determination of trace amount of molybdenum in various water samples by spectrophotometry after preconcentration using microcrystalline triphenylmethane. The preconcentration factor is from 83 (500 ml water sample was enriched to 6.0 ml) to 166 (1000 ml water sample was enriched to 6.0 ml). The detection limit is 1.3 × 10⁻⁵ mg l⁻¹ and the linearity is maintained in the concentration range 3.8 × 10⁻³ to 0.36 mg l⁻¹ with a correlation coefficient of 0.9998. The recoveries are in the range of 93.5-104%. The relative standard deviation is 1.8-2.9%. Analytical results obtained with this novel method are very satisfactory.     

A Novel Polyoxovanadium Cluster Shell: β‐As8V14O42

The hydrothermal reaction of VOSO₄, As₂O₅, piperazine and H₂O produces [H₂N(CH₂)₄NH₂]₄[β‐As₈V₁₄O₄₂(SO₄)]·2HSO₄ ( 1 ), which is the first arsenic‐vanadium cluster containing a spherical β‐As₈V₁₄O₄₂ shell. The structure of this compound was characterized by single crystal X‐ray diffraction, elemental analysis, TG, and IR spectrum. Crystal data for 1 : Orthorhombic, Cmcm, a = 15.369(1) Å, b = 16.404(1) Å, c = 25.772(1) Å, V = 6497.4(9) ų, Z = 4.     

破碎-絮凝法分离细长碳纳米管与碳纤维

根据碳纤维与细长碳纳米管耐磨性能与絮凝沉降性能的差异，提出了一种有效分离细长碳纳米管与碳纤维的物理方法——破碎-絮凝法.该方法包括研磨破碎、液相分散、絮凝沉降、过滤分离等步骤，可高效去除混杂于细长碳纳米管样品中的碳纤维，同时还可去除螺旋状碳纤维及细小碳颗粒等易悬浮杂质.纯化过程对细长碳纳米管无损伤.用电子显微镜和热重分析表征了纯化效果，并初步分析了纯化机理.     

运动对去卵巢大鼠骨元素代谢的影响

用测定骨元素含量的方法，分析了运动对正常大鼠和切除双侧卵巢后的大鼠骨元素代谢的影响。将健康4个月龄雌性SD大鼠44只随机分成5组：（1）非去势非运动组；（2）非去势＋运动组；（3）假去势非运动组；（4）去势非运动组；（5）去势＋运动组。运动组用大鼠专用跑台中等运动强度训练，持续10周。结果表明，去卵巢大鼠骨Ca,Mg,S,Mn,Zn等含量显著降低，P含量显著增加。运动训练可使去卵巢大鼠降低的骨Ca,Mg,S,Mn,Zn等含量显著回升，骨P含量显著回降。提示中等强度运动训练可对抗由于去卵巢所引起的骨元素代谢紊乱。     

Density functional study of HO(H2O)n (n = 1–3) clusters

The hydrogen bonding complexes HO(H₂O)_n (n = 1–3) were completely investigated in the present study using DFT and MP2 methods at varied basis set levels from 6‐31++G(d,p) to 6‐311++G(2d,2p). For n = 1 two, for n = 2 two, and for n = 3 five reasonable geometries are considered. The optimized geometric parameters and interaction energies for various complexes at different levels are estimated. The infrared spectrum frequencies and IR intensities of the most stable structures are reported. Finally, thermochemistry studies are also carried out. The results indicate that the formation and the number of hydrogen bonding have played an important role in the structures and relative stabilities of different complexes. © 2004 Wiley Periodicals, Inc. Int J Quantum Chem, 2005