Advanced Materials Research Vols. 430-432

Abstract: The kinetics of the reaction is essential for the synthesis of polyurethane. In this study, the reaction kinetics and polymerization conditions in two-step process of isophorone diisocyante (IPDI) and polypropylene glycol (PPG) with organo-tin mixed catalyst were investigated by chemical titration. The results showed that the reaction obeyed the second-order equation of step-growth polymerization, the rate constants of IPDI and PPG reaction at 50, 60 and 70°C were 0.0161, 0.0373 and 0.0806 kg•mol-1•min-1，respectively. The activation energy obtained from the result was 74.25 kJ•mol-1. The polyurethane with number molecular weight 38721 was synthesized and was characterized by Fourier transform infrared (FTIR).

Abstract: The failure components made of silicon is an important issue in the electronic and nano-technological developments. A study on the near-crack-tip deformation of single-crystal silicon wafer under tensile load was presented. The strain formulas around the crack tip of mode I crack were deduced from linear elastic fracture mechanics. The strain fields around the crack tip were simulated and analyzed in detail.

Abstract: The construction method of the joint section connecting bridge and tunnel was simulated by FEM. After Calculating and comparing the result of stresses and effect of displacement-control in the surrounding rock under three methods of construction, it shown that the side heading method was very advantageous for the stress concentration, and the CRD method provided a good control of bottom heave, as for the top heave, the double side heading method was more favorable. From the dynamic analysis, the vehicle load is found to have, though small, wide influence. What’s more, the lapping distance between the bridge and tunnel is better more than 4m, and the influence from the high running speed should be paid attention to.

Abstract: Most popular agents for protein cleavage are proteolytic enzymes, but they require more rigorous hydrolytic conditions, and it is very difficulty to separate them from the productions. In this paper, an new artificial metalloprotease, Cu(II) complex of cyclen (Cu(II)Cyc) using chitosan as supporter, was designed and synthesized successfully. The hydrolytic efficient under different conditions was measured and confirmed with HPLC, SDS-PAGE, further more. Some reaction conditions, such as pH, temperature, were researched, and the results show that the optimum reaction time was 48 h, temperature was 60 °C respectively, The observed rate constants for trypsase inhibitor cleavage was 1.006×10-2 h-1 under above conditions, and the observed rate constants was 2.120×10-2 h-1 when the pH was 9.0. This paper suggested that the chitosan metal complexes could efficiently accelerate the hydrolysis reaction.

Abstract: The Cu thin films were deposited on P type Si (111) substrates by ionized cluster beam (ICB) technique. The surface morphology and roughness of Cu thin films were studied at different deposition condition by atomic force microscopy (AFM). The results show that the average grain size and surface roughness of the Cu thin films deposited at an acceleration voltage of 3 kV is smaller than other conditions.

Abstract: In order to improve the physical and electrochemical hydrogen storage kinetics of the Mg2Ni-type alloys, Ni in the alloy was partially substituted by M (M=Co, Cu). Melt-spinning technology was used for the preparation of the Mg20Ni10-xMx (M=Co, Cu; x=0, 1, 2, 3, 4) hydrogen storage alloys. The structures of the as-cast and spun alloys are characterized by XRD, SEM and TEM. The physical and electrochemical hydrogen storage kinetics of the alloys is measured. The results show that the as-spun (M=Cu) alloys hold an entire nanocrystalline structure, whereas the as-spun (M=Co) alloys exhibit a nanocrystalline and amorphous structure, confirming that the substitution of Co for Ni facilitates the glass formation in the Mg2Ni-type alloy. The substitution of M (M=Co, Cu) for Ni engenders an insignificant effect on the hydrogen absorption kinetics of the alloys, but it markedly ameliorates the hydrogen desorption kinetics of the alloys and the high rate discharge ability. With an increase of the M (M=Co, Cu) content from 0 to 4, the hydrogen desorption ratio ( ) is enhanced form 20.0% to 65.43% for the as-spun (20 m/s) alloy (M=Co), and from 20.0% to 52.88% for the as-spun (20 m/s) alloy (M=Cu).

Abstract: This paper introduces the method of deformation mechanism of steel channel’s cold bending forming process through numerical simulation, mainly analysis the changing rule of stress and strain in the deformation of the fifth pass. Simulation results show that, in global terms, stress and strain of the typical position value increases with time going.

Abstract: This article researched the cementation and hardening mechanisms of cement asphalt emulsion and waterborne epoxy mortar by using the XRD, and heat of hydration testing methods. The results of this study show that the mixture of cement with epoxy and cement- asphalt-epoxy are endothermic reaction. There are occurring endothermic reactions between cement with epoxy. The waterborne epoxy resin and basic structure unit of ettringite [Ca3Al(OH)6•12H2O] were reacted and formed Ca-complex at earlier period of hydration.

Abstract: The in vitro antimicrobial activity of the essential oil from needles of Pinus yunnanensis Franch.var tenuifolia was investigated. The essential oil was obtained by hydro-distillation and analyzed by gas chromatography-mass spectrometry (GC-MS) method. The major compound of the essential oil was α-pinene (22.542%), followed by β-caryophyllene (16.636%), 1,2,4a,5,8,8a-hexahydro-4,7-dimethyl-1-(1-methylethyl)-naphthalene (5.085%), β-cubebene (4.779%), elixene (4.442%), α-cadinol (3.528%),α-caryophyllene (3.459%) and limonene (3.428%). The antimicrobial activity of oil was evaluated by using disc diffusion and agar dilution methods, respectively. The results indicated that the essential oil held moderate antimicrobial activity against tested microorganisms. The essential oil did not differ remarkably in its antibacterial and antifungal activities. The minimum inhibitory concentrations (MICs) were 40 ml/l for bacterial strains, and 80 ml/l for fungal strains.

Abstract: Firstly a graft copolymer was synthesized by graft copolymerization of starch with acrylamide (AM) in inverse emulsion, and then the copolymer was deaminated and post-cross-linked by heating to produce three-dimensional superabsorbent polymer. The effect of initiate conditions, composition and concentration of emulsifier, cross-linking methods and conditions were investigated. The results show that the optimized conditions are as follows: The mixture of (NH4)2S2O8-(NH2)2CO are used as initiators, and molar ratio of initiators and acrylamide is 1.4∶105; The mixture of Span20 and Tween80 with the mass ratio of mSpan20∶mTween80=80∶20 is used as emulsifier, and the total mass fraction of the mixed emulsifier is 7% of the oil phase; Post-cross-linking method is used, and the conditions are Tc=130 °C – 140 °C, t=30 min. The water-absorbing capacity of superabsorbent polymer obtained under such conditions can reach up to 1300 – 1400 g/g in distilled water and 400 -500 g/g in saline, respectively. Its water retention rate can reach more than 90%.