Nd_nSrFe_nO_(3n+1)(n=1,2,3,∞)的合成、结构、电性质和磁性研究

合成了NdnSrFenO3n+1(n=1,2 ,3,∞ ) 系列复合氧化物 ,其中Nd3SrFe3O10 是首次合成 ,并研究了其晶体结构 ,IR谱以及 30 0～ 110 0K之间的电性质和磁性质。相对于NdSrFeO4 ,Nd2 SrFe2 O7中ab平面上的Fe O键较短而c轴方向的Fe O键较长 ;而NdFeO3中只有一种Fe O键 ,在 30 0～110 0K之间 ,NdSrFeO4 ,显反铁磁性行为 ,Nd2 SrFe2 O7表现为亚铁磁性 ,而Nd3SrFe3O10 和NdFeO3为顺磁性。随着n值的增大 ,该系列氧化物电阻率增大 ,这可能是系统四价Fe离子浓度减小的结果。     

Structural,textural and catalytic properties of pure and Li-doped NiO/Al2O3 and CuO/Al2O3 catalysts

Pure and Li-doped NiO/Al₂O₃ and CuO/Al₂O₃ catalysts were prepared to contain 2, 4 and 8 wt.% of Ni and Cu, respectively. The structural properties were determined using DTA, XRD and FTIR techniques, and the textural properties of the catalysts were determined from their adsorption–desorption isotherms of nitrogen at 77 K. The chemisorption of hydrogen at 473–823 K with the pre-reduced catalysts was measured. The data obtained allowed the determination of the metal surface area, S (m²/g); the percentage of metal distribution, R; and the diameter of metal crystallite, d (nm). The amount of surface acidity, measured in mmol/g, was determined from the amount of chemisorbed pyridine necessary to completely inhibit the catalytic dehydration (DHD) of isopropanol. The conversion of isopropanol at 533–623 K was investigated using the micro-catalytic pulse technique. DTA, XRD and FTIR indicated that NiO and CuO exist as separate phases with crystallite sizes too small to be detected. No evidence has been gathered to indicate the existence of an aluminate phase.With the increase of metal loading, the surface area decreased whereas the total pore volume and the mean pore radius increased. Conversion of iso-propanol to propene proceeded via (DHD) on surface acid sites, and conversion of isopropanol to acetone proceeded via dehydrogenation (DHG) on redox sites. DHD and DHG exhibited first-order kinetics, and the rates of both reactions increased with temperature, with the latter being more temperature-dependent.     

Properties of Low Density Polyethylene/Polypropylene Blends

ABSTRACT

The role of di-cumyl peroxide (DCP) as compatibilizer in low density Polyethylene/Polypropylene (LDPE/PP) blends has been explored. Mixtures with varying LDPE/PP ratio were prepared in a Brabender plasticorder and tested for their mechanical properties and calorimetric response. Then peroxide was added at concentrations up to 0.5%, and the mechanical properties of the these new blends were measured. Also, the mixing torque, melt flow index and gel content of the above products were recorded as a function of peroxide concentration. It was found that the incorporation of DCP restricts the thermoplastic characteristics of the melt, which was primarily attributed to branching which occurs in LDPE. This results in an enhancement in the adhesive bonding between the two polymers mainly due to chain entanglements. This was further supported by the fact that mechanical properties of the treated blend were significantly improved.     

Full CI benchmark calculations for molecular properties

Full CI calculations of first- and second-order properties are presented to provide benchmark results for comparisons with other methods, such as multireference CI(MRCI). The full CI(FCI) polarizability of F^– is computed using a double zeta plus polarization plus diffuse basis set. These FCI results are compared to those obtained at other levels of theory; the CASSCF/MRCI with Davidson correction results are in excellent agreement with the FCI. Differences between the polarizability results computed as a (numerical) second derivative of the energy or as an induced dipole moment are also discussed. FCI calculations are presented for the dipole moment and polarizability of HF, CH₂ and SiH₂ using a DZP basis set. Again, the CASSCF/MRCI values are in excellent agreement with the FCI results, whereas SDCI values, whether computed as an expectation value or as an energy derivative, are much worse. The results obtained using the CPF approach are in considerably better agreement with the FCI results than SDCI, and are similar in quality to the SDCI energy derivative results with the inclusion of Davidson's correction.     

A new synthesis of trifluoromethanethiolates—characterization and properties of tetramethylammonium, cesium and di(benzo-15-crown-5)cesium trifluoromethanethiolates

[NMe₄]SCF₃, CsSCF₃ and [(B-15-C-5)₂Cs]SCF₃ (B-15-C-5: benzo-15-crown-5) are formed from reactions of the corresponding fluorides, trimethyl(trifluoromethyl)silane, Me₃SiCF₃, and elemental sulfur in glyme or THF. All compounds are colorless to pale ochre solids decomposing significantly above ambient temperature. Excellent agreement between experimental and theoretical vibrational frequencies, calculated at the B3PW91 level of theory, impressively confirms the salt-like nature of [NMe₄]SCF₃.The properties of the title compounds as nucleophilic SCF₃ transfer reagents were checked with a variety of organic, organometallic and inorganic compounds.     

铋先生的一天

In this article, the periodic table is described as a thriving "city", and Mr. Bismuth is one of the citizens. Through a day's life of Mr. Bismuth, the main properties and applications of bismuth and its compounds are demonstrated.     

Synthesis and properties of novel segmented polyurethanes containing alkyl phosphatidylcholine side groups

In this article, we report the synthesis and properties of novel segmented polyurethanes containing alkyl phosphatidylcholine side groups. Alkyl phosphatidylcholine groups were attached to the hard blocks of the polyurethanes. A novel diol, 9-(2-hydroxy-1-hydroxymethyl-1-methyl-ethylcarbamoyl)-nonyl-phosphatidylcholine (HDEAPC), was synthesized and characterized by FTIR, ¹H-NMR and mass spectroscopy. Two types of polyurethanes, poly(ether urethane)s and poly(carbonate urethane)s, containing alkyl phosphatidylcholine side groups were synthesized using methylenebis(phenylene isocyanate) (MDI), polytetramethyleneoxide (PTMO), poly(1,6-hexyl-1,5-pentylcarbonate) diol (PHPCD), 1,4-butanediol (BDO) and HDEAPC. The obtained phosphatidylcholine polyurethanes had relatively high molecular weights and good mechanical strength, as characterized by GPC and Instron. XPS and contact angle studies revealed that there was enrichment of alkyl phosphatidylcholine side groups near the surface of the polyurethanes. Biocompatibility was evaluated by protein adsorption using conventional polyurethanes as references. The surface of phosphatidylcholine poly(carbonate urethane)s effectively suppressed protein adsorption.     

三烷氧基(β-酯基)乙基锗的合成及性质

生物及临床实验结果表明β-羧基乙基锗倍半氧化物[简式为(GeCH_2CH_2COOH)_2O_3]工具有抗癌等广泛的生物活性,且毒性极低。最近,我们又发现该化合物是一种具有双重性能的放射增敏剂,并合成了末见报道的类似物β-(N-芳基酰胺基)乙基锗倍半氧化物[简式(GeCH_2CH_2CONHAr)_2O_3],研究了其抗癌活性。本文所要报道的新有机锗化合物包括7个三烷氧基(β-酯基)乙基锗化合物[简式(R~2O)_3GeCH_2CHR~1COOR~2]和6个β-三氯锗基丙酸酯类化合物[简式Cl_3GeCH_2CHR~1COOR~2]。     

The effect of radiation on the physical and chemical properties of polyethylene containing an antioxidant and/or other additives

This paper describes the effect of an antioxidant, a monomer and fillers (silica or carbon black), alone or in certain combinations with each other, on the mechanical and chemical response of a low density polyethylene to exposure to ionizing radiation. If chain scission is a significant factor in the radiolysis of a polymer, then the relation between sol fraction and Young's modulus or ultimate elongation (both at 160°C) should change depending on whether an additive inhibits or enhances crosslinking. Such additives do not significantly or consistently alter the relation between these properties in a low density polyethylene, indicating that chain scission is not a significant feature of the radiolysis of this polymer.     

聚ε-己内酯/β-磷酸三钙共混物的制备与性能

研究了β－磷酸三钙和表面接枝改性β－磷酸三钙与聚ε－己内酯共混物的制备,共混体系的界面相互作用、热性能和力学性能。获得了全生物降解的聚ε－己内酯／β－磷酸三钙共混物材料。     

壳聚糖保鲜膜的研究进展

壳聚糖是非常有价值的天然高分子材料 ,壳聚糖膜保鲜食品 (特别是果蔬 )已引起越来越多的国家和研究机构的重视 ,本文综述了近年来关于壳聚糖保鲜膜的制备、性能、应用的研究进展。     

有机及金属有机苯乙炔树状分子体系的非线性光学性质的理论研究

应用密度泛函理论研究了一系列有机及金属有机苯乙炔树状分子的激发态性质和非线性光学性质。计算的电子吸收光谱显示这些树状分子均在低能区域有一个最强的吸收;此外,金属有机体系的吸收光谱和有机体系相比发生了明显的红移。响应性质的计算结果表明共轭体系的扩展和金属有机基团的引入都使得苯乙炔树状分子的非线性光学极化率显著增加,尤其是含Ru体系,其β和γ值呈数量级增长。对于有机体系和含Pd体系,发生在共轭体系内部的π→π*电荷跃迁是产生分子一阶和二阶超极化率的主要原因。而含Ru体系相当大的非线性响应则主要起源于Ru的轨道到共轭体系的π*的跃迁,同时与Ru相邻的C≡C到共轭体系的π→π*跃迁起着辅助贡献。     

A study of morphological,thermal, rheological and barrier properties of Poly(3-hydroxybutyrate-Co-3-Hydroxyvalerate)/polylactide blends prepared by melt mixing

The paper aims to study blend properties of biodegradable polymers of poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) and polylactide (PLA) prepared by melt mixing. Blend compositions based on PHBV/PLA were investigated according to the following weight ratios, i.e. 100/0, 75/25, 50/50, 25/75 and 0/100 wt%. The study showed through scanning electron microscopy (SEM) that blends of PHBV/PLA are not miscible. This is consistent with differential scanning calorimetry (DSC) data which indicate the presence of two distinct glass transition temperatures (T_g) and melting temperatures (T_m), attributed to the neat polymers, over all the range of blend compositions. Water and oxygen barrier properties of PHBV/PLA blends are significantly improved with increasing the PHBV content in the blend. Further, morphological analyzes indicated that increasing the PHBV content in the polymer blends results in increasing the PLA crystallinity due to the finely dispersed PHBV crystals acting as a filler and a nucleating agent for PLA. On the other hand, the addition of PLA to the blend results in a very impressive increase in the complex viscosity of PHBV. Moreover, the rheological data showed that, excluding the specific behavior of the neat polymers at low frequencies, i.e. less than 0.1 Hz, the complex viscosity of PHBV/PLA blends fits the mixing law well.     

Synthesis and evaluation of antioxidant and antibacterial properties of morin complexes

This study examines the interaction of Mg(II) and Ca(II) with morin (2′,3,4′,5,7-pentahydroxyflavone) in conjunction with the appraisal of antioxidant and biological properties of the complexes. The complexes were characterized by UV-Vis spectroscopy, FT-IR, ¹H NMR, ¹³C NMR, thermal, and elemental analyses. The complexes have also been studied to determine metal?:?ligand stoichiometry. For antioxidant studies, it may be induced that complex formation increases the scavenging ability because of the differential and selective role of metals in free radical scavenging. The bioactivity studies show that both complexes have remarkable antibacterial properties against Micrococcus flavus and Staphylococcus aureus.     

Dilithium Hexaboride,Li2B6

Li₂B₆ is formed from the elements as transparent red microcrystalline compound (Li : B = 1 : 3; Mo crucible in closed Nb ampoule; 1723 K; 4 h). Single crystals are grown from a lithium silicide melt with large Li excess at 1923 K. Li₂B₆ is a semiconductor with electron as well as Li⁺ ionic conductivity which dominates above 600 K. Microcrystalline samples react with H₂O liberating gases and forming a brownish amorphous product, but larger crystals are not very sensitive. – Li₂B₆ crystallizes tetragonally in a new tP16 structure type which is a variant of the CaB₆ structure (a = 5.975 Å, c = 4.189 Å; Z = 2; space group P4/mbm). The [B₆^2–] net of the polymeric octahedro-anion is slightly distorted to give space for the insertion of a (3²434) net of the Li⁺ cations in the cavities (d(B–B)_endo = 1.766 Å; d(B–B)_exo = 1.720 Å; d(Li–B) = 2.363 Å; d(Li–Li) = 3.094 Å). The incomplete occupancy of the Li position (80%) and the electron density at a further position (20%) indicate the mobility of the Li⁺ cations.     

聚合物/层状硅酸盐纳米复合材料的性能

取合物／层状硅酸盐纳米复合材料是近十年发展起来的一类新型材料，即使硅酸盐纳米填料的含量很低，一般在5％（wt）以下，就使该类材料具有许多优良的性能，如杨氏模量，储能模量，热稳定性，气体阻隔性及阻燃性等均有较大的提高。本文综述了该类材料的性能。     

L-苏氨酸铜(Ⅱ)超分子配合物的合成、晶体结构及性质

合成了L-苏氨酸铜(Ⅱ)超分子配合物[Cu(C4H8NO3)2].H2O,通过元素分析、红外、差热-热重、紫外光谱和单晶结构对其结构进行确认。该化合物由1个Cu(Ⅱ)离子、2个L-苏氨酸阴离子和1分子结晶水组成,其中氨基酸的羧基氧原子及氨基氮原子与铜(Ⅱ)离子配位,形成六配位拉长八面体构型,单胞之间通过分子间氢键构成三维网状超分子体系。配合物在水溶液中的紫外吸收波长为233nm,固态荧光发射之间通过分子间氢键构成三维网状超分子体系。配合物在水溶液中的紫外吸收波长为233nm,固态荧光发射出现在357nm。电化学行为显示,配合物在玻碳电极上为不可逆的氧化还原过程,反应过程受扩散控制。     

Study of blends of HDPE and different grades of CaCO3. Part I. Factorial experimental design

Calcium carbonate (CaCO₃)/high density polyethylene (HDPE) composites were prepared in a HAAKE twin screw extruder. The influence of the CaCO₃ particle size and content and the processing conditions were investigated by using a factorial experimental design. The dependent variables studied were tensile properties, such as Young's modulus, stress at break and toughness, and the rheological property, zero-shear viscosity, η₀. Preliminary results have shown that the most significant processing variables were content and mineral filler type. Mathematical modeling has given us a more efficient evaluation of the results obtained and has become an important tool in the development of this work.     

Fluorine-Containing Functional Group-Based Energetic Materials

Molecules featuring fluorine-containing functional groups exhibit outstanding properties with high density, low sensitivity, excellent thermal stability, and good energetic performance due to the strong electron-withdrawing ability and high density of fluorine. Hence, they play a pivotal role in the field of energetic materials. In light of current theoretical and experimental reports, this review systematically focuses on three types of energetic materials possessing fluorine-containing functional groups F- and NF₂- substituted trinitromethyl groups (C(NO₂)₂F, C(NO₂)₂NF₂), trifluoromethyl group (CF₃), and difluoroamino and pentafluorosulfone groups (NF₂, SF₅) and investigates the synthetic methods, physicochemical parameters, and energetic properties of each. The incorporation of fluorine-containing functional moieties is critical for the development of novel high energy density materials, and is rapidly being adopted in the design of energetic materials.     

Molecular Structure and Magnetic Properties of the Binuclear Phthalato-Bridged Species Bis[(N-(2-(Diethylamino)Ethyl)Salicylidenaminato)-Copper(II)] Trihydrate

The crystal structure of ( w -phthalato)bis[(N-(2-(diethylamino)ethyl)-salicylidenaminato)copper(II)-trihydrate,[Cu₂(salNet₂)₂(w m phthal)] · 3H₂O, where salNet₂= N-(2-(diethylamino)ethyl)salicylidenaminate, has been determined by single-crystal X-ray analysis. It crystallizes in the monoclinic system, space group P2₁/c, with a = 19.9109(9), b = 10.0465(4), c = 18.5837(8)Å, and g = 100.625(1)°. In the molecular structure the two copper(II) ions are bridged by the phthalato ligand coordinated in an amphimonodentate mode and the local geometry around both copper(II) ions is square planar. Magnetic susceptibility data for the complex as a function of temperature show weak exchange interactions. The fitting of these data to the HDVV (? = -2J ? ₁ ?₂), S₁ = S₂ = 1/2 spin exchange model, yields a 2J value of -0.34 cm^-1. An orbital interpretation of the observed weak antiferromagnetic interactions is presented based on the results of extended Hückel calculations on a model molecule.