Theoretical study of the thermal rearrangement of chloromethylsilanes, and its mechanism

The thermal rearrangement reactions of chloromethylsilane, (chloromethyl)dimethylsilane, and (chloromethyl)vinylsilane have been studied by use of the density functional theory method at the B3LYP/6-311G(d, p) level. The structures of the reactants, transition states, and the products were determined and fully optimized. The geometries of the different stationary points and the harmonic vibrational frequencies were calculated at the same level. The results showed that thermal rearrangement of the chloromethylsilanes occurred via one pathway. The chlorine atom migrated from the carbon atom to the silicon atom, and the hydrogen atom migrated simultaneously from the silicon atom to the carbon atom through a double-three-membered-ring transition state, forming methylchlorosilane, trimethylchlorosilane, and vinylmethylchlorosilane. The energy barriers of the three rearrangements calculated at the B3LYP/6-311G(d, p) level were 217.4, 201.6, and 208.7 kJ mol^?1, respectively. The effects of alkyl substituents on silicon atom are discussed. Changes of thermodynamic functions, equilibrium constant, and reaction rate constant were calculated in accordance with Eyring transition-state theory over the temperature range 400–1,500 K.     

Syntheses and Crystal Structures of Two One-dimensional Cobalt(Ⅱ) Compounds with the Flexible Dipyridyl Ligan

Two one-dimensional cobalt(Ⅱ) compounds {[Co(Hbpma)(H2O)4 ] 2 ·3SO 4 ·4.5H2O} n1 and {[Co(Hbpma)(NCS) 3 (H2O)]·2.85H2O}n2 (bpma = N,N -bis(3-pyridylmethyl)amine) have been synthesized and structurally characterized by single-crystal X-ray diffraction. Complex 1 crystallizes in triclinic, space group P1 with a = 15.8780(5), b = 16.2187(5), c = 16.4858(5) , α = 91.0420(10), β = 94.5190(10), γ = 101.4360(10)°, V = 4145.7(2) 3 , C 24 H 53 Co 2 N 6 O 24.50 S 3 , M r = 1031.76, Z = 4, D c = 1.653 g/cm 3 , μ(MoKα) = 1.046 mm -1 , F(000) = 2148, S = 1.017, the final R = 0.0269 and wR = 0.0644 for 13032 observed reflections (I > 2σ(I)). For complex 2, it belongs to triclinic, space group P1 with a = 9.3761(11), b = 10.5814(13), c = 11.2972(14) , α = 85.472(2), β = 88.058(2), γ = 76.203(2)°, V = 1085.0(2) 3 , C 15 H 21.70 CoN 6 O 3.85 S 3 , M r = 502.79, Z = 2, D c = 1.539 g/cm 3 , μ(MoKα) = 1.112 mm -1 , F(000) = 519, S = 1.070, the final R = 0.0358 and wR = 0.0899 for 3466 observed reflections (I > 2σ(I)). Two complexes 1 and 2 are both found to be one-dimensional coordination polymers bridged by the protonated bpma ligands, which are assembled into three-dimensional supramolecular structures through the hydrogen bonding interactions and π-π packing interactions.     

盘旋螺旋槽管强化传热研究

用实验的方法以水为介质研究了同轴换热器的流动与传热,Re范围为30000到100000。研究表明管内摩擦阻力系数是相同情况下圆管的4到5倍,总体传热系数随管内Re的增大而增大,当Re较大时提高壳侧速度对换热性能的提升更有利。采用数值模拟的方法分别研究了同轴换热器整体的换热与流动,且和实验结果进行了比较,研究表明,受离心力的影响流体在管内产生了掺混流动,掺混流动的程度随螺距的减小而加剧,增加槽深减少了参与掺混的流体量,流体之间的掺混对换热具有积极的影响。     

Simulation of the gelation process of hydrogel droplets in 3D bioprinting

The aim of this work is to numerically simulate the gelation of a crosslinking polymer, which is a very complex process involving chemical reactions and phase transitions from a viscous fluid to a viscoelastic solid. A phenomenological model is proposed to simulate the gelation process of agarose droplets, considering the thermal boundary conditions. The numerical model is implemented using the finite element package FlexPDE. The temperature- and time-dependent degree of gelation and the deformation of the droplets during the gelation process are investigated. (© 2016 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim)     

An examination of tissue engineered scaffolds in a bioreactor

Replacement tissues, designed to fill in articular cartilage defects, should exhibit the same properties as the native material. The aim of this study is to foster the understanding of, firstly, the mechanical behavior of the material itself and, secondly, the influence of cultivation parameters on cell seeded implants as well as on cell migration into acellular implants. In this study, acellular cartilage replacement material is theoretically, numerically and experimentally investigated regarding its viscoelastic properties, where a phenomenological model for practical applications is developed. Furthermore, remodeling and cell migration are investigated. (© 2016 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim)     

磁载光催化剂Fe3O4/C/TiO2的制备及对三氯苯酚的降解

以FeCl3为铁源,葡萄糖为碳源,钛酸四丁酯为钛源,采用水热法制备了磁载光催化剂Fe3O4/C/TiO2,用TEM、EDX、VSM、XRD和IR对Fe3O4/C/TiO2的粒径、形貌和物相等进行了表征。研究了该催化剂对三氯苯酚的降解性能,探讨了其重复使用的可能性,用荧光光谱法推测了可能的反应机理。结果表明该材料结合了光催化与可再生的优点,1 g·L-1 Fe3O4/C/TiO2在18 W紫外灯下,50 min内可将三氯苯酚降解97.9%以上,6次循环使用后降解率仍保持在95.1%,降解过程中有羟基自由基生成。     

二氧化硅负载磷钼酸铯催化苯液相硝化反应的研究

采用溶胶-凝胶法制备了二氧化硅负载磷钼酸铯催化剂,利用XRD、IR以及电位滴定等方法对催化剂进行了表征,并初步评价了催化剂的苯液相硝化反应催化性能。结果表明,溶胶-凝胶法制备的二氧化硅负载磷钼酸铯具有典型的Keggin结构,且在苯液相硝化反应中表现出优良的催化性能;催化剂用量、反应时间和温度等反应参数对催化苯液相硝化反应有明显的影响,在优化实验条件下,苯硝化转化率可达95%;催化剂可回收重复使用,多次反应后催化剂活性组分有所损失,但催化剂整体物相和结构没有发生明显变化。     

New Cytotoxic Triterpenoids from the Aerial Parts of Euphorbia sieboldiana

Phytochemical investigation of the EtOH extract of Euphorbia sieboldiana led to the isolation of four new oleanane‐type triterpenoids, (1β,2α,3β,19β)‐1,2,3,19‐tetrahydroxyolean‐12‐en‐28‐oic acid, (1β,3β,19β)‐1,3,19‐trihydroxyolean‐12‐en‐28‐oic acid, (1β,2α,3β,16β,19β)‐1,2,3,16,19‐pentahydroxyolean‐12‐en‐28‐oic acid, and (1β,2α,3β,19β,23)‐1,2,3,19,23‐pentahydroxyolean‐12‐en‐28‐oic acid, along with 16 known compounds. Their structures were established by extensive 1D‐ and 2D‐NMR, as well as other spectral analyses. Biological evaluation of the four new triterpenoids revealed potent cytotoxic activities against HeLa and Hep‐G2 cells.     

3-取代-12-氧代-N,N-双(2-氯乙基)脱氧胆酰胺的合成及其抑制癌细胞活性

以7-脱氧胆酸(1)为原料,由Jones试剂氧化得到3,12-二氧代-7-脱氧胆酸(2),然后与双(2-氯乙基)胺反应,得到3,12-二氧代-N,N-双(2-氯乙基)-7-脱氧胆酰胺(4),进一步通过对化合物4中的3-位羰基进行官能团转换,得到2个3-位分别被肟基、缩胺硫腙基取代的12-氧代-N,N-双(2-氯乙基)-7-脱氧胆酰胺类型化合物。同时,初步测试了合成物对肿瘤细胞增殖抑制活性,结果表明,化合物对宫颈癌细胞的生长有显著的抑制活性。