Sol-gel Preparation of Fluoridated Hydroxyapatite in Ca(NO3)2-PO(OH)3− x (OEt) x -HPF6 System

Fluoridated hydroxyapatite (FHA) has been successfully synthesized via sol-gel method with HPF₆ as the fluorine containing reagent. The chemical reactions induced by HPF₆ addition and the formation process of fluoridated hydroxyapatite (FHA) are investigated. The hydrolysis and alcoholysis of HPF₆ release F ion into the solution which, in turn, reacts with Ca ion to form nanocrystalline CaF₂ (nc-CaF₂). These nc-CaF₂ improves the gelation ability of the system through formation of F‒H hydrogen bonding between F in nc-CaF₂ and H in P precursors. Increasing HPF₆ leads to more nc-CaF₂ thus less Ca(NO₃)₂ in the dried gel, or the presence of nc-CaF₂ in the gel suppresses the formation of Ca(NO₃)₂. At elevated firing temperatures, the P containing groups react with each other to form condensed phosphate. These condensed calcium phosphate, nc-CaF₂/Ca(NO₃)₂, reacts with the rest of the amorphous phase to form FHA phase at above 400°C.     

高温煤气脱硫 Ⅰ.铁基脱硫剂的相态特征和活性

用穆斯堡尔谱考察了氧化铁脱硫剂在高温煤气中还原及硫化时的铁形态变化规律。在反应开始阶段，原脱硫剂中的α-Fe2O3即被迅速还原成Fe3O,Fe3O4可进一步还原转化成α-Fe。反应初期Fe3O4和α-Fe都参与脱硫反应，其中α-Fe具有较高的脱硫活性，对整个脱硫过程而言α-Fe是主要的脱硫活性相。铁化合物与硅铝氧化物载体间存在相互作用，形成磁微 晶颗粒及少量γ-Fe。在高温煤气条件下，FeS是唯一的铁硫化物，θ－Fe3C则是α－Fe转化中的主要产物。适量的θ－F e3C对脱硫有促进作用。     

Two polymorphs of cobalt(II) imidazolate polymers synthesized solvothermally by using one organic template N,N-dimethylacetamide

Two structurally different polymorphs of cobalt(II) imidazolate frameworks are solvothermally synthesized by using N,N-dimethylacetamide as a template: The polymorph 6 (a = 9.797 (4) angstroms, b = 15.301(6) angstroms, c =14.902(6) angstroms, beta = 98.904(6) degrees, monoclinic, P21/n) shows structures of silicate CaAl2Si2O8 with CrB4 topology, while polymorph 7 (a = 15.173(4) angstroms, b = 15.173(4) angstroms, c = 19.089(5) angstroms, Pbca) shows CaGa2O4-related topological structures. In addition, the 7' (a = 15.9712(18) angstroms, b = 15.9253(19) angstroms, c = 18.475(2) angstroms, Pbca), a compound isostructural with 7, is synthesized by using cyclohexanol as a template. Thus, these cobalt(II) imidazolate polymers are reminiscent of the zeolite syntheses in that not only the same topological structure can be synthesized by using the different organic templates, but also different topological structures can be synthesized by using the same organic template.     

Solventless polymerization: spatial migration of a catalyst to form polymeric thin films in microchannels

This paper reports a simple, additive process to generate patterned polymer films without using any solvent. This process involves a highly efficient catalyst, a Grubbs's catalyst, and a volatile monomer, norbornene. The catalyst and monomers have higher local concentrations inside the microchannels, formed by contacting poly(dimethylsiloxane) stamps to a solid surface, and allow the polymeric thin films to be defined by the microchannels. The patterned thin film serves as an excellent resistant to reactive ion etching, which promises that this process is a complementary, useful alternative to spin-coating and plasma polymerization in microfabrication.     

协萃络合物结构的研究——二(1-苯基 -3-甲基-4-三氟乙酰基吡唑啉酮-5)-(1，10菲啰啉)合钴(II)的合成、表征与晶体结构的测定

合成了二(1-苯基-3-甲基-4-三氟乙酰基吡唑啉酮-5)-(1,10菲啰啉)合钴(Ⅱ)混合配体络合物单晶, 由元素分析确定其组成为Co(C_(12)H_3F_3O_2N_2)_2·(C_(12)H_8N_2)。通过溶解性、摩尔电导, 磁性、中红外光谱、远红外光谱、差热、热重分析研究了该化合物的有关性质。用四园单晶衍射仪, 测定了该络合物的分子及晶体结构。晶体属单斜晶系, P2_(l/o)空间群,晶胞参数为:a=1.0422(3) nm, b=1.6462(2) nm, c=2.0678(3) nm, β=75.86(1)°, V=3.4402(1.6) nm, Z=4, F(000)=1580, d_(calc)=1.50 g cm~(-3), d_(exp.)=1.492g cm~(-3)。经最小二乘法修正后, 最终偏差因子R=0.0716。配合物中钴的配位数为六, 分子中有四个氧来自两个双齿配体PMTFP, 两个氮原子由phen所提供。     

INVESTIGATION OF MICROSTRUCTURE AND CONDUCTIVE MECHANISM OF HIGH DENSITY POLYETHYLENE/CARBON BLACK PARTICLE COMPOSITE BY POSITRON ANNIHILATION LIFETIME SPECTROSCOPY

The microstructure and conductive mechanism of high density polyethylene/carbon black (HDPE/CB) compositewere investigated by positron annihilation lifetime spectroscopy (PALS). The PALS were measured in two series of samples,one with various CB contents in the composites and the other with various γ-irradiation doses in HDPE/CB compositecontaining 20 wt% CB. It was found that CB particles distribute in the amorphous regions, the CB critical content value inHDPE/CB composite is about 16.7 wtO/ and the suitable γ-irradiation dose for improving the conductive behavior ofHDPE/CB composite is about 20 Mrad. T'he result observed for the second set of samples suggests that γ-irradiation causesnot only cross-linking in amorphous regions but also destruction of the partial crystalline structure. Therefore, a suitableirradiation dose, about 20 Mrad, can induce sufficient cross-linking in the amorphous regions without enhancing thedecomposition of crystalline structure, so that the positive temperature coefficient (PTC) effect remains while the negativetemperature coefficient (NTC) effect is suppressed. A new interpretation of the conductive mechanism, which might providea more detailed explanation of the PTC effect and the NTC effect has been proposed.     

Two Key Amino Acids Variant of α-l-arabinofuranosidase from Bacillus subtilis Str. 168 with Altered Activity for Selective Conversion Ginsenoside Rc to Rd

α-l-arabinofuranosidase is a subfamily of glycosidases involved in the hydrolysis of l-arabinofuranosidic bonds, especially in those of the terminal non-reducing arabinofuranosyl residues of glycosides, from which efficient glycoside hydrolases can be screened for the transformation of ginsenosides. In this study, the ginsenoside Rc-hydrolyzing α-l-arabinofuranosidase gene, BsAbfA, was cloned from Bacilus subtilis, and its codons were optimized for efficient expression in E. coli BL21 (DE3). The recombinant protein BsAbfA fused with an N-terminal His-tag was overexpressed and purified, and then subjected to enzymatic characterization. Site-directed mutagenesis of BsAbfA was performed to verify the catalytic site, and the molecular mechanism of BsAbfA catalyzing ginsenoside Rc was analyzed by molecular docking, using the homology model of sequence alignment with other β-glycosidases. The results show that the purified BsAbfA had a specific activity of 32.6 U/mg. Under optimal conditions (pH 5, 40 °C), the kinetic parameters K_m of BsAbfA for pNP-α-Araf and ginsenoside Rc were 0.6 mM and 0.4 mM, while the K_cat/K_m were 181.5 s⁻¹ mM⁻¹ and 197.8 s⁻¹ mM⁻¹, respectively. More than 90% of ginsenoside Rc could be transformed by 12 U/mL purified BsAbfA at 40 °C and pH 5 in 24 h. The results of molecular docking and site-directed mutagenesis suggested that the E173 and E292 variants for BsAbfA are important in recognizing ginsenoside Rc effectively, and to make it enter the active pocket to hydrolyze the outer arabinofuranosyl moieties at C₂₀ position. These remarkable properties and the catalytic mechanism of BsAbfA provide a good alternative for the effective biotransformation of the major ginsenoside Rc into Rd.     

胆盐与磷酸钙的相互作用

胆汁的pH条件下(pH=6～8)，应该生成无定形磷酸钙(ACP)，而在胆结石中磷酸钙通常以羟基磷灰石的形式出现.利用谱学方法研究了ACP与胆盐的作用.结果表明，胆盐以胶团的形式与ACP作用，在溶液中形成复合胶团，使其溶解度增加.不同类型胆盐与ACP的作用能力不同：脱氧胆酸钠(NaDC) > 牛磺胆酸钠(NaTC) > 胆酸钠(NaC).胆盐与ACP中结合钙的亲和能力大于结合钙的亲和能力，使ACP在胆汁的环境下容易转化为羟基磷灰石.     

A New Octadecanuclear Copper(II)‐Lanthanide(III) Cluster Complex: Synthesis and Structural Characterization of [Cu12Nd6(OH)24(betaine)16(NO3)3(H2O)10](NO3)[PF6]14·5H2O

The new octadecanuclear Cu‐Ln complex, [Cu₁₂Nd₆(OH)₂₄(betaine)₁₆(NO₃)₃(H₂O)₁₀](NO₃)[PF₆]₁₄·5H₂O, was synthesized, which crystallizes in triclinic P1¯ space group, a = 18.649(6)Å, b = 20.363(7)Å, c = 19.865(7)Å, α = 116.61(2)°, β = 91.99(2)°, γ = 117.93(2)°, V = 5666(3)ų. Its crystal structure features a [Cu₁₂Nd₆(OH)₂₄(betaine)₁₆(NO₃)₃(H₂O)₁₀]¹⁵⁺ core of pseudocubic O_h symmetry, with the six Nd ions positioned at the vertices of a regular octahedron and the twelve Cu ions located at the midpoints of the twelve octahedral edges. The Cu‐Nd metal framework may be viewed as a cuboctahedron, which is interconnected by twenty‐four μ₃‐OH bridges that are each linked to one Nd ion and two Cu ions. In the centre of metal polyhedron, there is an encapsulated NO₃^— anion that exhibits a multi‐ coordinating mode.