Advanced Materials Research Vol. 716

Abstract: Respiratory route is one of the major exposure routes to nanoparticles. The environmental agent aluminum is intensively investigated for the association with development of neurodegeneration. To evaluate potential neurotoxicity induced by aluminum oxide (Al₂O₃) nanoparticles, male rats were intranasally instilled with 0.1 or 1 (Al) mg/kg nanoAl₂O₃ or aluminum chloride (AlCl₃) every two days for 60 days, using pure water as vehicle control. Neurotoxicity effects were determined by behavioural studies and immunohistochemistry staining of ED1 and beta-amyloid precursor protein (Aβ). Neither of nanoAl₂O₃ treated groups showed significant alterations in Morris water maze tests, however, increased escape latency were observed in 1mg/kg AlCl₃ treated rats. Further, upregulation of ED1 expression were showed in olfactory bulb of 1 mg/kg nanoAl₂O₃ and AlCl₃ exposed rats. Massive Aβ expressions were observed in whole brain of 1mg/kg (Al) AlCl₃ treated rats. ED1 expression is a marker of microglia/macrophages activation, suggesting stimulus of Al₂O₃ nanoparticles to microglia/macrophages located in olfactory bulb and perivascular areas. In these studies, Al₂O₃ nanoparticles didnt show any alterations on spacial learning behaviours of rats and expression of Aβ of neuron, therefore, display lower neural effects than AlCl₃.

Abstract: Based on the interfacial reaction model between Ti and ZrO₂ in gravity field, taking account of the effect of electromagnetic field, a comprehensive numerical model for simulation of heat and mass transfer is established to study the interfacial reaction between liquid Ti and ZrO₂ in electromagnetic field. With the proposed model, numerical simulations are preformed to investigate the influences of pouring temperature, holding time on the oxygen concentration and reactive layer thickness in metal. The results show that both the oxygen concentration and the thickness of reactive layer in metal increase with increasing the holding time and the pouring temperature. The thickness of reactive layer in electromagnetic field is greater than that in gravity field.

Abstract: The present study was undertaken to investigate the effect of metallurgical parameters on the hardness and microstructural characterisations of as-cast and heat-treated 356 and 319 alloys, with the aim of adjusting these parameters to produce castings of suitable hardness and Fe-intermetallic volume fractions for subsequent use in studies relating to the machinability of these alloys. Hardness measurements were carried out on specimens prepared from 356 and 319 alloys in the as-cast and heat-treated conditions, using different combinations of grain refining, Sr-modification, and alloying additions. Aging treatments were carried out at 155 °C, 180 °C, 200 °C, and 220 °C for 4 h, followed by air cooling, as well as at 180 °C and 220 °C for 2, 4, 6, and 8 h. Peak hardness was observed in 356 alloys when aging was carried out at 180oC/4h. In the case of unmodified or modified 356 alloys containing mostly α-Fe intermetallics, aging at 180 °C up to 8h produced a sharp rise in hardness during the first two hours of aging, followed by a broad peak or plateau over the 2-8 h aging period. Aging at 220 °C revealed a hardness peak at 2h aging time for both 356 and 319 alloys. Addition of Mg to unmodified or modified 319 alloys produced a remarkable increase in hardness at all aging temperatures. This may be explained on the basis of the combined effect of Cu-and Mg-intermetallics in the 319 alloys, where hardening during aging occurs by the cooperative precipitation of Al₂Cu and Mg₂Si phase particles.[, ] For 356 and 384 alloys, the Mg-containing 319 alloys (~same Mg concentration as in 356 alloys) displayed higher hardness values than the 356 alloys for the aged condition, where hardening occurs by cooperative precipitation of Al₂Cu and Mg₂Si phase particles in 319 alloys compared to only Mg₂Si precipitation in the case of 356 alloys.

Abstract: Biodegradable polylactide (PLA) composites/pristine multiwalled carbon nanotubes (P-CNT) composites with three different aspect ratios (length to diameter) are prepared by coagulation method. Isothermal crystallization and morphology of neat PLA and its composites are further investigated to clarify the effects of aspect ratio of CNT on the crystallization behaviors of PLA in its composites. Results show that the different aspect ratio CNT exhibit substantially different effects on PLA crystallization. It is interesting to find that small aspect ratio CNT (CNT-S) greatly promotes nucleation rate than big aspect ratio CNT (CNT-L).

Abstract: Self-compaction concrete is a new green concrete featuring self-leveling, self-compaction, low noise and low consumption of labor force. Nowadays, a large number of super high-rise buildings (h>400m) are under construction around the world, the complicated structures and dense reinforcement placement has brought numerous inconveniences to construction of concrete. Research on high strength / ultra-high strength self-compaction concrete thus becomes a hotspot. The porous structure of zeolite powder can help absorb the water reducing agent and then release it slowly in concrete mixture. With the low slump loss it produces, the prepared C100UHP-SCC can resist slump loss for over 3 hours. Test of super-high pumping at a height of 411m is carried out in the West Tower program at Pearl River New Town of Guangzhou (the building height is 441m). Drilled core test for L-shaped component indicates a dense internal structure, so it has a desirable self-compaction and capacity to pass through dense reinforcement.

Abstract: The nucleophilic addition reaction was happened between 2-pyrrolidone and acrylonitrile in the toluene solvent using the PTC and sodium hydroxide respectively as phase transfer agent and catalyst. The nitrile fraction which seemed as pale yellow liquid was obtained by rectification. The effect of types and amount of PTC on gas chromatographic purity and yield of product were studied. The results showed that a better product could be obtained by using BTEAC as the catalyst compared to the CTAB and TBA. The optimum experimental condition was determined by the orthogonal experimental method. The yield was as high up to 94.2% when the quality score of BTEAC accounted for 0.5% of the total feeding mass, the concentration of aqueous solution of sodium hydroxide was 10%, acrylonitrile excessed 5%, gas chromatographic purity of the product was 98.5%.

Abstract: Vanadium oxide films were deposited on ITO (Indium Tin oxide) glass substrates at room temperature byreactive DC magnetron sputtering.The Vanadium oxide films were varied the nitrogen flow rateto investigate composition, microstructure, optical properties, and electrochromic properties determined by X-ray diffraction, field-emission scanning electron microscope (FE-SEM), UV-visible spectrometer, andcyclic voltammetry. Experimental results indicatedthat V₂O₅filmsreactively sputtered at oxygen flow rates of 15 sccm had better electrochromic property and optimalperformance.

Abstract: TiO₂ has been considered the most promising photocatalyst for the degradation of volatile organic compounds (VOCs). However, the application of pure TiO₂ is limited because it requires UV activation with a high-energy band gap, and < 5% of the solar radiation can be used. In order to improve the photocatalytic performance, TiO₂ with Zr and N doping can be activated by the UV-vis radiation available in sunlight to perform solar photocatalysis. The properties of the N-Zr-TiO₂ catalysts are characterised by SEM and DRS. The results exhibit that the optical response of TiO₂ is shifted from UV to the visible light region with the introduction of Zr and N. The photocatalytic tests indicate that the N-Zr-TiO₂ demonstrate a high activity for the degradation of formaldehyde.

Abstract: In the presence of sodium dodecyl benzene sulfate (SDBS) and under the irradiation of microwave, silver nitrate was reduced by alcohol to prepare stabile green and yellow silver nanoparticles in size of 41 nm and 71 nm respectively. Yellow silver nanoparticles have two resonance Rayleigh scattering (RRS) peaks at 440nm and 465nm. Green silver nanoparticles exhibit three RRS peaks at 420nm, 465nm and 585nm. Gray nanoparticles, which prepared in absence of SDBS, show a strong RRS at 465nm. Silver nanoparticles modified by dodecyl benzene sulfate (DBS) can react with cationic surfactant to exhibit novel RRS property. The concentration of some cationic surfactants is liner to the enhanced RRS intensity at 465nm.