Applied Mechanics and Materials Vols. 80-81

Abstract: A phenolic syntan GA-SHBS had been synthesized by radical copolymerization of gallic acid (GA) and sodium 4-hydroxybenzenesulfonate (SHBS) using horseradish peroxides (HRP)/H2O2 as catalyst. The effects of monomer ratio, reaction temperature and HRP dosage on syntan were discussed. The optimum performance of GA-SHBS was got when the molar ratio of GA: SHBS is 1:1 in the presence of 5 mg HRP at 35°C in pH 7.0. The chemical structure of copolymer was characterized by means of FTIR and NMR. The mechanism of polymerization between GA and SHBS and binding mechanism between syntans and leather fibers were proposed. The copolymer was used in making leather as tanning agent and retanning agent respectively, applied results showed that the Ts of tanned leather can reach to 75.6°C, re-tanned leather has the merits of good uniformity, fullness, softness, fine grain and non-plastic feel etc. Syntan also has good permeability, excellent tanning performance and dyeing effect.

Abstract: The chitosan was degraded by hydrochloric acid and the effects of concentration of chitosan, amount of hydrochloric acid, reaction temperature and reaction time on the viscosity of chitosan were investigated. The results showed that the degraded chitosan with low viscosity could be prepared when chitosan (wt 6%) was dissolved in acetic acid solution and hydrochloric acid (wt 3%) at 90°C for 6 h to decrease the viscosity from 7.52 mPa·s to 2.48 mPa·s. Then, a graft copolymer was synthesized by copolymerization of degraded chitosan with methacrylic acid (MAA) and acrylamide (AAM) by using horseradish peroxidase (HRP)/H₂O₂/acetylacetone (ACAC) as initiator. The structures of original chitosan, degraded chitosan and the copolymer were characterized by FTIR. The copolymer was applied to the leather industry as an amphoteric retanning agent. The applied results showed that the retanned leather had the merits of good uniformity fullness softness, strong selecting filling properties, good dyeing ability and antimicrobial activity.

Abstract: The chloroprene rubber (CR) and trans isoprene rubber (TPI) combined with methyl methacrylate (MMA) and α-Methylacrylic acid (MAA) to obtain a tetrabasic graft copolymer adhesive in a low poisonous mixing solvent. The effect of solvent, ratio of CR and TPI, benzoyl peroxide (BPO) amount, the dosage of MMA and MAA on the adhesive properties was investigated by studied the relationship between graft percentage (GP) and the T peel strength (T-PS) of various graft copolymer adhesives. The results showed that an excellent tetrabasic graft copolymer adhesive was obtained by a copolymerization of CR, TPI, MMA and MAA was 85 g, 15 g, 0.8 g, 60 g and 10 g using 0.8g BPO as initiator in a low poisnouos mixing solvent consisted of 124 g ethyl acetate (EA), 44 g pyroacetic spirit (PK) and 32 g toluene (TOL) at 85 °C for 5 h. The chemical structure of the tetrabasic graft copolymer adhesive was characterized by FTIR.

Abstract: A new type of magnetic polymer microspheres with super paramagnetic properties were prepared by a co-precipitation method. Atomic absorption spectroscopy (AAS), X-ray diffraction (XRD), transmission electron microscope (TEM) and scanning electron microscopy (SEM) were used to analyze Fe content, micro morphology, particle size and phase structure of the products. Results indicate that the content of Fe in the microspheres is up to 5.25 *105ug/g. The main phase of the product is Fe3O4. The average particle sizes of the products are ~30nm.

Abstract: Lead rubber bearings (LRB) is a new type of earthquake-resistance rubber bearings, formed by inserting lead-core into ordinary laminated rubber bearings, vertical supporting, horizontal displacement and hysteretic damping are hung in single unit together. Because lead-core can dissipate seismic energy and increase stiffness under load simultaneously, most of the requirements of the Seismic isolation system can be satisfied , the material-device has been found widespread application prospect in bridge Engineering. Equivalent linear model of hysteretic characteristics, computational method and the varying range of design parameters of LRB are presented. A full-bridge model of multi-span simple supported bridge with LRB is established in which box beam、LRB and piers are taken into account as a whole. By changing the property of earthquake excitation, ground motion intensity, vehicle speed and so on, the response of Bridge vibration system are analyzed, response law and characteristics of Bridge with LRB under different excitations are investigated systematically, compared with bridge with common bearings.

Abstract: Orientin, isolated from bamboo leaves, is an important natural antioxidant. It has been identified that orientin could protect myocardium against ischemia/reperfusion (I/R) injury. But the precise mechanism of this protective effect is still elusive. The ubiquitin-proteasome system (UPS) plays a central role in regulating a variety of critical cellular processes. Recently, the cardiac UPS has become increasingly recognized as the key regulator of cardiac function under both physiological and pathological conditions. Previous studies indicated that alterations in the UPS function are involved in the pathogenesis and progression of a variety of cardiac diseases including myocardial ischemia/reperfusion. The proteasome is the proteolytically active core of UPS and could cause various diseases when it malfunctions. Accordingly, the proteasome has become an attractive target for pharmaceutical interventions. In addition, the relationship of orientin and UPS in mediating I/R-induced cardiomyocytes injury is still unclear. Here, we used H9c2 cardiomytocytes to explore the relationship of orientin-induced cardioprotection and proteasome inhibition during I/R process. Our findings suggested that orientin could reduce H9c2 cells apoptosis subjected to I/R injury partly through surpressing the proteasome inhition. Further investigation revealed that this effect was associated with orientin-attenuated reactive oxygen species (ROS) generation and depolarization of mitochondrial membrane potential (Δψm). Orientin also enhanced Bcl-2 protein level, decreased the expression levels of Bax and Smac/DIABLO. Our results also indicated that this beneficial effect of orientin on Bax expression was dramatically attenuated by MG132, the proteasomal inhibitor. In summary, we demonstrated that orientin exerts protective functions in H9c2 cardiomytocytes against I/R-induced apoptosis partially through suppressing proteasome inhibition, and mitochondrial apoptotic pathway is probably involved in this effect.

Abstract: In this study, the biosorption of Malachite Green, a cationic dye from aqueous solution onto pretreated biomass of Penicilium sp. was examined. The biosorption studies were carried out under various parameters such as initial pH, contact time and initial dye concentration. The experimental results show that optimum pH for efficient dye biosorption was found to be 5.0-6.0 for pretreated biomass. The bosorption capacity was increased with the increasing initial dye concentration in studied dye concentration range. The kinetic data obtained at different concentrations were analyzed using pseudo-first-order, pseudo-second-order and intra-particle diffusion models. It was obtained that the biosorption process followed the pseudo-second-order kinetic model.

Abstract: The bioceramic hydroxyapaptie (HA) is frequently used as coat in titanium medical implants improving bone fixation and thus increasing a lifetime of the implant. However, its joining to the titanium alloy is not satisfactorily good. The aim of this work is to produce TiO₂ and HA gradient coatings on Ti6Al4V alloy to improve the interface joining. Compared the microstructures of cross section of Ti6Al4V-HA coating and Ti6Al4V-TiO₂ /HA gradient coatings. HA coatings were obtained by sol-gel method with sol solutions prepared from calcium nitrate tetrahydrate and triethyl phosphate as the calcium and phosphorous sources. And TiO2 coatings were obtained from Tetra Butyl Titanate and absolute ethyl alcohol as the sources by sol-gel method too. The configuration and structure were investigated with scanning electron microscopy (SEM) and X-ray diffraction (XRD) techniques. The results demonstrated that the TiO₂/HA gradient coatings have a homogeneous microstructure. The TiO₂ coating made the HA coating adhere to the Ti-6Al-4V substrate well.

Abstract: Ti-Nb alloys were prepared by powder metallurgy. Their microstructures are detected by the XRD diffraction and are observed using an optical microscope. The mechanical properties are tested using a dynamic mechanical analysis (DMA) Q800 from TA Instruments in single cantilever mode and using a 100 KN MTS testing machine with control software. It has been found that the sintered Ti-Nb alloys possess the stable α and β phases and the amount in β phase increases with increasing Nb content. The water quenched Ti-35.4Nb alloy contains α^,, and β_M. The as-sintered alloy has higher yield stress and storage modulus than the water quenched Ti-35.4Nb alloy, which is resulted from the α phase with high modulus in the as-sintered alloy. The ω phase can be precipitated from β_M when the water quenched Ti-35.4Nb alloy is aged at 300 °C, causing the modulus to increase since ω phase has large modulus.

Abstract: Using mixing casting method, in-situ composite technology, rapid solidification process and powder metallurgic method etc. can parpare metal matrix nano composites successfully. Comparing with other preparing methods, mixing casting method is with many advantages such as easy to manipulate, low cost, the composites obtained with better properties. CNTs strengthening metal matrix composites are with more dense organization and higher tensile strength, micro hardness, fatigue strength, and abrasive resistance etc. comparing with traditional metal matrix composites. So CNTs strengthening metal matrix composites are widely applied in industrial areas. In this article, the prepare methods of CNTs strengthening metal matrix composites are summed up, the micro organization and mechanical properties of CNTs strengthening metal matrix composites are described and whose future work is prospected.