Advanced Materials Research Vol. 950

Abstract: Porous 1 dimensional (1D) ZnO nanofibers were synthesized by electrospinning technology and sequent annealing process. The ZnO nanofibers have many nanopores in it and connect to each other to form a porous film. The diameters of the nanofibers are about 100 nm, and their lengths are so long as tens of millimeters. Owing to the porous nanofibers based matrix has 1D channels and high isoelectric point, the prepared ZnO porous film is wonderful platform to immobilize glucose oxidase enzyme for glucose biosensing. The as-fabricated biosensor exhibited high sensitivity (69 μA/mMcm^-2), fast response (3 s) and low detection limit (10 μM), due to the nanomaterial with large surface-to-volume ratio for enzyme immobilization and excellent electrical properties. The biosensors can be fabricated controllably and repeatedly. These excellent results indicate the biosensors are attractive for application.

Abstract: We report that crystallization property of amorphous Sb₂Te₃ can be significantly improved via Al doping. However, the effect of Al on the structure and electrical properties of crystalline Sb₂Te₃ is not clear, which is valuable for phase change memory. In this work, we find that Al addition could increase the crystallization temperature and change the structure. The results show that both nucleation and growth of crystallite are suppressed by Al doping. Based on ab initio calculation, we have validated the formations of Al-Sb and Al-Te bonds in doped films and the effect of Al on the structure and properties of crystalline Sb₂Te₃. Especially for 10 at% Al doped Sb₂Te₃ (Al-Sb-Te) film, which exhibits better thermal stability and might be a good candidate material for phase change memory.

Abstract: Hyaluronic acid is an important polysaccharide of various physiological functions. Nowadays, it is produced mainly through microbial fermentation of Streptococcus zooepidemicus. HA production in more safe and efficient genetic modified GRAS strains is a hot research area. Bacillus subtilis, Lactococcus lactis, Streptococcus thermophiles, Agrobacterium sp. , and some Escherichia coli strains, which were GRAS strains, had been selected for genetic engineering to express hyaluronic acid. Here, we provide a comprehensive review of HA production by these genetic modified GRAS strains.

Abstract: Have been reactively synthesized bio-composites material that has a good in mechanical strength and fuel resistance. The starting material for the manufacture of bio-composite was recycled PP (rPP) modified AA, reinforcement kenaf fiber (KF), the mixture of magnesium hydroxide (MH) and aluminum hydroxide (ATH) without or with boric acid (BA) as a fire retardant. The burning rate (BR) and tensile strength (TS) test were used ASTM D635 and D638, respectively. The presence of mixture fire retardant [MH/ATH] with ratio of 15/5 in the bio-composites can effectively reduce their burning rate (BR). Biodegradability of the bio-composites, which is reflected by weight loss (WL) is achieved arise after burying the bio-composites in garbage soil for four months. However, the presence of mixture fire retardant could marginally decrease the TS of the bio-composites.

Abstract: This research describes morphological aspect of BC-PVA nanocomposite asscaffold for bone tissue that was synthesized by adding PVA to Gluconacetobacterxylinus fermentation medium. PVA concentrationswere varied as 0,3,6,9, and 12 % (w/v) of the medium. The culture was agitated with magnetic stirrer for 28 days. Freeze drying was then conducted to obtain dry BC/PVA nanocomposite. Some nanocomposite samples subjected to sonication treatments. The morphology of BC-PVA nanocomposite was examined by Scanning Electron Microscope (SEM) whileits surface area and pore characteristic were determined by nitrogen adsorption of BJH method (BET device). SEM images showed the smallest fiber diameter of approximately 35 nm andnanocomposite surface that was smoother with higher PVA content in the fermentation medium. The sonicationtreatmentcould enhance nanocomposite surface area from 17,2 m2/g to 72,7 m2/g for pure BC sample and from 9,9 m2/g to 14,3 m2/g for 12% PVA sample. BC/PVA nanocompisite had smaller pore diameter than pure BC and its size increased with more PVA content in the fermentation medium.PVA could modify BC morphology bymakinga hindrance on cellulose nanofiber sothat fiber agglomeration could be avoided andthe sonicationtreatmentshowedto enhance this phenomena.

Abstract: A base-catalyzed process was applied to the synthesis C₁₈-silicananoparticles.The base-catalyzed process led to the rearrangement of spherical particles to form a flower-like aggregation of 300-nm silica particles. IR and TGA supported the success of the modification. The extraction of di-methyl phthalate (DMP) was successfully achieved (Fig. 1) in the ngrange. Fig. 1 Extraction of DMP silica nanoparticles

Abstract: Al₂O₃/PVDF-HFP based polymer electrolyte was prepared by the phase transfer method with different mass ratios of organic solvent and non-organic solvent. The solid polymer electrolyte was characterized by means of SEM, FTIR and AC impedance methods. The results show that the optimum mass ratio of organic solvent to non-organic solvent is 1:0.3 and the optimum mass ratio of Al₂O₃ is 7%. The liquid absorption rate of the polymer electrolyte is 225%. The lithium ionic conductivity of the polymer electrolyte at room temperature is about 1.75×10⁻³ S·cm^-1, and the LiCoO₂/Al₂O₃/PVDF-HFP/Li cell has good cycle performance.

Abstract: Study shows that gold can resist the formation of insulating oxide films that could interfere with reliable contact operation. So the gold coatings are often used in the contacts of separable electrical connectors and other devices. In this article, the corrosion test method is carried to show the porosity of specimens in gold coatings and the testing procedure is based on JIS standards. In addition to corrosion atmosphere, there is a sliding between the contact surfaces of the connector, which would affect the resistance of the connector contact materials. This paper studies the complicated effects of the corrosion environment and sliding on the dynamic resistance of the contacts materials of Au plated. Series of inspections and analytical research methods are introduced in this article. The surface morphology of specimens after corrosion test is observed by stereoscopic microscope and scanning electron microscope (SEM). Chemical constitution was examined by X-ray energy spectrum. The contact resistances were measured by four-point method. The experiment results show that after corrosion test by SO₂ with JIS corrosion test, the corrosion products appear islands-like spots on gold plating surface after corrosion test. The corrosion degree of gold plating specimens is decreased with the increase of the thickness of gold coatings. The results show that corrosion environment and sliding has a more complex and significant impact on the performance of the contact materials than single-factors, and the tests are closer to the real working environment.

Abstract: Highly bright-fluorescent N (nitrogen), S (sulfur) co-doped graphene quantum dots (GQDs) were synthesized through an modified hydrothermal method. The doped GQDs are smaller than 10 nm in size in average and stable in aqueous solution. Unlike many reports on graphene oxide (GO), the as-synthesized doped GQDs exhibit bright blue photoluminescence (PL) emission and the emission wavelength is excitation-independent. The intriguling results indicate that GQDs may have great potential in the optic and optoelectronic applications.