CHARACTERISTICS OF THE STRAIN Lactobacillus plantarum UL487 ISOLATED FROM TOFU (HUE)

Lactobacillus plantarum is widely used in many fields, especially in medicine. In this study, besides thestrain’s morphology (i.e, the colony and the cell under microscrope and scan electronic microscope), antibacterial activities against some pathogenic bacteria and the nucleotide sequences encoded for bacteriocin PlnA, PlnEF and the cold shock protein (Csp) of L. plantarum UL487 isolated form Tofu (Hue) were studiedby agar diffusion method and cloning. The results showed that: i) the morphology of the colony and the cell of the strain were typical for lactic acid bacteria; ii) UL487 owned antibacterial activities against some pathogenic bacteria such as Staphylococcus aureus VTCCB 658, Bacillus cereus VTCCB 613 and Salmonella enterica VTCCB 480; and iii) the nucleotide sequences encoded for bacteriocin PlnA, PlnEF and the amino acid of the cold shock protein (Csp) of the strain were 96%, 99% and 94% identical to those of the L. plantarum in the Gen Bank, respectively.

Microstructure and Mechanical Properties of TiAlON/TiAlN/TiAl Films

TiAlON/TiAlN/TiAl hard films are prepared by multi-arc ion plating technology using the Ti-50Al (at%) alloy target. The high speed steel (HSS) is adopted as substrate. The surface and cross-fracture morphology, the surface and cross-fracture compositions and the phase structures of the as-deposited TiAlON/TiAlN/TiAl hard films are observed and measured by scan electronic microscope (SEM), energy dispersive spectroscopy (EDS) and X-ray diffraction (XRD). The mechanical properties, including micro-hardness and adhesive strength between film and substrate, of the as-deposited TiAlON/TiAlN/TiAl hard films are investigated. The effects of oxygen partial pressure on the as-deposited films are discussed. It is revealed that the increase of oxygen decreased liquid droplets distribution density to some extent, caused complicated phase structure. Nevertheless, the good adhesive strength and the improved hardness with a maximum of 3900HV are achieved.

Procedure and Discussion of Failure Analysis in Iron-Steel Materials

The failure analysis of the H13 steel hot-forging mould is the main content in the open experiment. The scan electronic microscope and the optical microscope are used to analyze the failure workpiece in this experiment. The over-high quenching temperature, the too low drawing temperature, the insufficient drawing time and frequency, the over-high hardness value are the main reasons of fracture failure of the mould. The work environment of the failure materials, the heat treatment processing, the metallographic analysis, the fracture analysis and the using of test standard are the important aspects which the students should know. The students can learn how to analyze problem and how to solve them from the open experiments which is a good teaching try.

Microstructure and Mechanical Properties of (CrTiNb)N Films

(CrTiNb)N hard reactive films are prepared by multi-arc ion plating technology using the combination of Ti-Nb alloy target and Cr target. The high speed steel (HSS) is adopted as substrate. The surface and cross-fracture morphology, the surface compositions and the phase structures of the as-deposited (CrTiNb)N films are observed and measured by scan electronic microscope (SEM) and X-ray diffraction (XRD). The mechanical properties including the micro-hardness, the adhesion between film and substrate, the friction and wear resistance of the as-deposited (CrTiNb)N films are systemically investigated. The effects of deposition bias voltage and the addition of Nb element on the as-deposited (CrTiNb)N films are discussed. It is revealed that the optimally comprehensive performances including the micro-hardness, the adhesion and also the friction resistance can be achieved by the (CrTiNb)N hard reactive films with bias voltage of 200V.

Effect of Type and Dosage of Activators on Strength of Repair Concretes

The different effect of chemical activators on mechanical properties and microstructure of cement-base repair materials were investigated. The microstructure of repair concrete was also analyzed by using scan electronic microscope (SEM). Test of mechanical properties indicate that the optimum chemical activator suitable to repair concrete with nearly 30% mineral materials replacement of cement is the type J-B, and the optimum addition is 5% dosage by weight of binders. The presence of chemical activator J-B increase the early strength and exert significantly advantageous affect on the later strength. Measurement of microstructure indicates that the surface of fly ash particle can be seen obvious pozzolanic reaction, and this is due to the presence of chemical activator which accelerate the pozzolanic reaction and densify the mortar pore structure.

Effect of Orientation of Reinforcements on the Quality of the Machined Surface in Machining Aluminium Composites

The precision turning experiments of aluminium composites reinforced with SiC whisker reinforcements were done by polycrystalloid diamond (PCD) tools. The measure analysis of the machined surface was carried out with Atom Force Microscope (AFM) and Scan Electronic Microscope (SEM). The roughness values of the machined surface were measured by Talysurf-6. The results show that the orientation of reinforcements in the machined surface will directly affect the deformation mechanism of SiC whiskers, microstructures of the machined surface, and to determine the quality of the machined surface. In the five types from A to E of SiC whisker orientation, the orientation of case A easily makes to produce SiC whisker deformation by cutting off directly, and to result in the best machined surface. However, for the orientation of case E, it easily makes to induce SiC whisker deformation by pulling out or pressing into aluminium matrix, and to produce the worst machined surface.

Formation Mechanism of the Slice and Rod-Like Cerium Dioxide Precursor Particles

Ultra-fine cerium dioxide precursor particles was prepared with cerium (III) nitrate hexahydrate (Ce (NO3)36H2O) and urea (CO(NH2)2) at 85°C by homogenous precipitation method. Effects of reaction and ageing time on the morphology of the precursor particles were studied, the morphology of precursor particles was characterized by scan electronic microscope and the crystallinity of the precursors was studied by X-ray diffraction. The result showed that the mono-dispersed spherical particles turned into flower and bundle-like particles as reaction time increasing, the particles turned into slice and rod-like particles as the ageing time increasing, the transition process occurred in ageing process was later than that in the reaction process, the spherical particles were less crystallization and the slice and the rod-like particles were at a state of fine crystallization.

Synthesis of Si-O-C Nanoballs by CVD of Polydimethylsiloxane

Here we reported that the Si-O-C nanoballs (SCONBs) were yielded from polyorganosiloxane, polydimethylsiloxane, by chemical vapor deposition (CVD) method. The composite nanoballs with a range of diameters from 50 to 200nm were composed of silicon, carbon and oxygen based on analysis of EDX. At the transmission electron microscope(TEM) and scan electronic microscope(SEM), two populations of nanoballs were found: around 200nm and 500nm. X-ray diffraction patterns demonstrated that the nanoballs were dominatingly amorphous. Temperature played an key role in size distribution of Si-O-C nanoballs, and the 850–900°C temperature range was typical for nanoparticles growth via CVD.

Study of Microstructure and Dynamic Mechanical Analysis of Biodegradable Tableware Produced with Corn Straw

This paper focused on biodegradable tableware processed with plant fiber, which were obtained by mechanical processing corn straw, abundant in Heilongjiang Province of China. Firstly, the microstructure characteristics of tableware were described by Scan Electronic Microscope (SEM). Secondly, the dynamic mechanical property of biodegradable tableware was analyzed by DMA, which will provide a reference to optimize the biodegradable tableware design in future. And the dynamic mechanical property of biodegradable tableware also was compared with the dynamic mechanical properties of the plastic snack box. The results showed that biodegradable tableware had a highly storage modulus (E′) originally, it was 3216MPa,while the maximum storage modulus (E′) of plastic snack box was 852MPa. And the results also indicated that the treat temperature has a significant effect on the dynamic mechanical properties of biodegradable tableware, as the treat temperature increased closely to 95°C, the biodegradable tableware appeared glassy transition, but the storage modulus (1650MPa) was still much higher than that of the plastic snack box.

Effect of Nano-Graphite on Friction Performance of Cu-Based Friction Material

The Cu-based friction materials with nano-graphite were prepared through powder metallurgy technology. The microstructure and friction performance were studied through scan electronic microscope (SEM) and friction tester, respectively. The results indicate that coefficient of the Cu-based friction materials with 2 wt% nano-graphite is high and stable. Comparing with the friction materials without n-C, the wear resistance and heat resistance of the friction materials with nano-graphite has been improved by 11 % and 25 %, respectively. The nano-graphite particles will reduce the abrasive wear and enhance the wear resistance of the Cu-based friction materials.