Advanced Materials Research Vols. 750-752

Abstract: The aim of the present study is to evaluate the cupric ion releases and cytotoxicity of Cu-bearing intrauterine device (IUD) with different surface areas. TCu380, GCu300 and MCu165 were selected and extracted with MEM for 24h. Inductively Coupled Plasma Mass Spectrometry (ICP-MS) was employed to determine the concentration of Cu ions. MTT assay was conducted to evaluate the cell viability of original and diluted extracts. Oxidative stress indicators such as superoxide dismutase (SOD) and lipid peroxidation (MDA) were measured. The results showed the concentration of Cu ions released from three kinds of IUDs were 114.836mg/L, 91.161mg/L and 85.750mg/L, respectively. Cell viability of all original IUDs extracts was around 10%. TCu380 showed more significant cytotoxicity and higher oxidative stress level than other two IUDs when extracts were diluted. The study suggested that there was a positive correlation between the quantity of released Cu ions and cell damage effect in Cu-IUDs. The mechanism of cytotoxicity might be elevation of oxidative stress.

Abstract: Gelatin, as an amphoteric polyelectrolyte, can combine with cationic or anionic organic compounds by ionic bond. In this work, two binary quaternary ammonium salts have been prepared from 1,2-ethanediamine and 1,4-butanediamine. The viscosity of aqueous gelatin solution containing these two organic salts is studied systematically, which verifies the occurrence of the crosslinking between the gelatin and the binary quaternary ammonium salts. This crosslinking improves the thermal stability of the dried gelatin.

Abstract: Hydroxyapatite (HA) has been widely used as a biomaterial because HA has excellent biocompatibility, but the mechanical properties of HA are not sufficiently strong for dental applications. To enhance these mechanical properties, zirconia (ZrO₂) has been introduced as a second phase material. However, doping of ZrO₂ favors HA decomposition at low temperatures. In this paper, the effect of adding ZrO₂ on HA decomposition is discussed. Experimental results in previous studies are compared with theoretical results of chemical equations. The ideal percentage of doped ZrO₂ should be <10 wt.% to prevent HA decomposition unless a special sintering method is applied.

Abstract: In order to improve the corrosion resistance of Mg alloys as degradable implant material, fluorine conversion coatings were synthesized on AZ31 magnesium alloy by immersion in hydrofluoric acid (HF) for different time. Potentiodynamic electrochemical technique and hydrogen evolution testing were employed to investigate the corrosion behavior of the coated alloys in Hanks solution. It is indicated that the fluoride conversion coating, which is compact and composed of MgF₂, can significantly decrease the degradation rate of Mg alloy AZ31 in Hanks solution. The most improved corrosion protection was achieved by immersion for 10 days. The corrosion current density was 40 times lower than that of the substrate and the hydrogen evolution rate of the coated sample was only one-fiftieth of the substrate.

Abstract: To expand the extent of conjugation with biologically active molecules (biopolymers, peptides, drugs, etc.) and biomaterial substrates, we synthesized a serial of poly (ethy1ene glycol) (PEG) derivatives (PEG-2000-NH₂, MPEG-1200-NH₂, and APEG-1200-NH₂) in three efficient steps. The end groups were characterized by ¹H NMR spectroscopy.

Abstract: Molecular imprinting technology（MIT）is a kind of new-emerging polymerizing technology with specific selectivity and affinity ability, An elucidation on the basic principles, and the broad applications of molecularly imprinted polymers (MIPs) in some fields are given in this paper. It also gives an overview of some recent development in the field and offers an insight into how the area is likely to evolve in the future.

Abstract: Superfine cement is an ideal grouting material of high-performance ultrafine particles. It has excellent permeability, higher strength and durability. One of the most important features of superfine cement is no pollution on environment. SHD and SCC are two kinds of cement which have different performance. Comparing particle size, initial setting time, compressive strength and plug rate of two kinds of superfine cement by experiment. The result of experiment shows that cement SCC has higher compressive strength and plug rate at higher temperatures.

Abstract: The thermal behavior of coal tar refined soft pitch (CTRSP) was investigated by using polarizing microscope with heating stage and thermogravimetric analyzer. The phenomena of carbonization regime process of CTRSP were observed directly in the micro-picture taken online. The results showed that the carbonization thermal dynamic process of CTRSP is divided into several typical stages. At 30-250°C,there is small molecular evaporation; at 250-390 °C,there is thermal decomposition and small molecular evaporation; at 390-480°C,there is the condensation of small molecules and radicals into macromolecules and directional arrangement generating small spheres; at 480-520°C,there is the coking stage; at 520-560°C, there is the semicokes dehydrogenation and shrinkage. The spherules are formed at about 390°C. The growth process of the spherules is divided into several stages: absorption optical isotropic matrix asphalt to grow, two spherule collision fusion and growth, finally (at 480-520°C) due to gravity is greater than surface tension small spheroid disintegration deformation and became fibrillar semicoke (at 520-560 °C). Thermogravimetric (TG) - differential thermogravimetry (DTG) curve are treated by Freeman-Carrolls non isothermal differential method, coal tar soft pitchs first-order reaction is from 253°C to 325°C, from 370 °C to 413°C two temperature stages, activation energy is 28.575 kJ/mol and 60.210 kJ/mol, pre-exponential factor is 2.328×10⁶ and 1.4833×10⁷, respectively. The microscopic picture recording was consistent with thermal heavy kinetic equation and the results confirmed that the chief of thermal decomposition reaction is operated from 253 °C to 325 °C, the most of condensation polymerization reaction is operated from 370 °C to 413 °C.

Abstract: A facile method to prepare well-dispersed Platinum nanoparticles (Pt NPs) on FTO and TiO₂ nanotube (TNTs) film was reported. The so-prepared Pt/FTO and Pt/TNT film electrodes are characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD). The results show Pt NPs have been dispersed on the supporting matrixs uniformly. Electrochemical investigations indicate that Pt/TNT has higher electrocatalytic activity and better tolerance to poisoning species in methanol oxidation than Pt/FTO, which can be ascribed to the high dispersion of Pt NPs on the TiO₂ nanotubes surface. The present method is promising for the design of high performance catalysts for direct methanol fuel cells.

Abstract: In this study, we first purposefully synthesized SAPO-11 and Na-ZSM-23 molecular sieves. The catalysts loaded with Cu were prepared by using seven typical carriers, including Montmorillonite-K10, USY, SAPO-11, Na-ZSM-23, γ-Al₂O₃, ZnO and MgO, and the performance of the catalysts was tested for amination of ethanol. The results demonstrate that the acid-base property of the carriers is closely related with the results of amination of ethanol over the catalysts. Among all these catalysts, 15%Cu/Na-ZSM-23 shows the highest yield of acetonitrile.