Advanced Materials Research Vols. 560-561

Abstract: The nanocrystalline surface was obtained on bulk pure nickel by using high-current pulsed electron beam (HCPEB) technique. The temperature field induced by HCPEB was numerically simulated. The structures of the nanocrystallized surface were characterized by scanning electron beam (SEM), which showed that after HCPEB irradiation, the initial coarse-grained structure on the surface was refined into fine grains with sizes of about 70nm. It was revealed that melting surface caused by HCPEB irradiation and subsequently rapid cooling was the dominant mechanism of the surface nanocrystallization of bulk nickel. The HCPEB technique provides a new method for rapid fabricating surface-nanocrystallized materials.

Abstract: Two inorganic compounds containing CO32- and SiO44- groups were introduced and ultrasound-aided coprecipitation method was applied to fabricate carbonated silicon-substituted hydroxyapatite (CSi-HA) nanopowder. The synthetic process was optimized and the crystalline phase, grain dimension and morphology of the CSi-HA nanopowder were characterized. The obtained results demonstrate that H3PO4 addition into alkaline Ca(OH)2 ammonia liquid with ultrasonic application can obviously prevent secondary phase formation and make the nascent HA product pure, highly dispersed and gel-like. The introduction of Na2SiO3 and Na2CO3 mixed solution as doping source into the nascent HA product with also continuous ultrasound utilization can effectively realize the ionic group substitution of HA by CO32- and SiO44- and make the final CSi-HA nanopowder fine and uniform. It was also found that the CSi-HA grain size shows a decrease trend with the increase of CO32- and SiO44- substitution in the experimental range.

Abstract: The novel photocatalyst of α-Fe₂O₃/Sb-doped SnO₂ (ATO) nanocomposites were fabricated by two-step process of hydrothermal and precipitation method. The structure, size, magnetic behavior and absorption property were characterized by XRD, TEM, VSM and UV-Vis absorption spectrum. The composites with low mole ratio of ATO have more pronounced photocatalytic activities. The optimum photocatalytic activity in our experiments appears at the mole ratio of n_Fe:n_Sn=1:0.25. The α-Fe₂O₃/Sb-doped SnO₂ nanocomposites have better photocatalytic activities than α-Fe₂O₃/SnO₂ nanocomposites. The results show that the doping of Sb ions can improve the capture ability of electrons and consequently enhance the photocatalytic activities of the composite system.

Abstract: In order to get highly monodispersed nanoparticles, a post-synthesis separation of nanopaticles polydisersed in size and shape is often desired, although the experimental conditions for the synthesis of nanoparticles are carefully controlled. Using continuous density gradient centrifugation, Ag nanospheres, nanocubes, and nanowires can be separated from polydisperse samples. Size and dimension analysis by sanning electron microscopy and absorption spectroscopy prove that density gradient centrifugation is a powerful method to obtain monodisersed nanoparticles.

Abstract: In this study, the nano-silver impregnated media (NAg-ball) was proposed to inactive E. coli in water. After 24 h of contact with NAg-ball, about 99 % removal of E. coli from the water sample with an initial bacteria loading oItalic textf 10³ - 10⁵ CFU/ml was observed. According 32 day repetitive use, periodical surface cleaning would be suggested to maintain the high inactivation lasting of NAg-ball. The dosing of 1: 20 (Nag-ball: water) was found to be the best and most suitable in a 500 L pilot scale. This result confirmed the existence of synergistic effect lower dose shall be expected to treat the same loading of bacteria for further larger scale. Toxicity Characteristic Leaching Procedure (TCLP) test revealed trace amount of Ag, Cu, Cr and Zn released from NAg-ball into the treated water sample. In conclusion, nano-silver impregnated media has very good inactivation performance on E. coli. This NAg-ball provides a safe, convenient and effective solution in drinking water treatment, especially in the mountain area.

Abstract: Electrospinning and its application in filtration area have been caught much attention because of the large surface-to-volume ratio of nanoweb , which affects the filtration efficiency by possibly giving more particle-capture sites. In this study, PAN is electrospun to produce ultra-fine nonwovens, and its characteristics as filter media are investigated.

Abstract: Here we report for on the functionalization of ordered cage-type mesoporous carbons through a simple oxidation using ammonium perchlorate (AP). The degree of functionalization can be easily controlled by the simple adjustment of the oxidation parameters such as oxidation time, AP concentration and oxidation temperature. The functionalized materials have been unambiguously characterized by XRD, nitrogen adsorption, FT-IR and TEM measurements. It has been found that the functionalized carbon nanocage, ‘‘carboxy carbon nanocage’’.

Abstract: InGaAs nanoflowers have been prepared on InP substrates by MOCVD, using TMIn, TMGa and AsH3 as reactive precursors at 420 oC. Through observation by scanning electron microscopy, we find that InGaAs nanoflowers are composed with blades and rods. The flower patterns are controlled by the growth temperature. The nanoflowers of InGaAs are disappeared, when we alter the growth temperature up and down. The InGaAs nanoflowers are In0.98Ga0.02As.

Abstract: The Microporous Poly(vinylidene Fluoride) (PVDF) Materials Were Prepared by Emulsion in the Article, and through Appropriate Methods to Characterize Considerable Specific Surface Area and Excellent Pore Structure. with DMF as Solvent, Ethanol as a Diluent to Dissolve and Dilute PVDF, by Virtue of this Method to Destroy the Morphology of PVDF Structure, that Changed the Spherical Structure to Porous Structure, and to Get the Different Pore Size and Specific Surface Area through Controling the Speed of Dripping Water. the Structure Information, Surface Morphology and Specific Surface Area Were Determined by XRD, SEM (or Field Emission) and Specific Surface Area and Pore Size Analyzer, then Found the Regulation about Control of Pore Size and Specific Surface Area Preliminary.

Abstract: The research explores gold nanoparticles (NPs)/PVA/carbon black composite film and their further applications in humidity sensor chips, which include: 1. Novel humidity sensitive Au NPs/PVA/carbon black composite film has been prepared; 2. Humidity sensor chips based on Au NPs/PVA/carbon black composite film devices has been fabricated. The initial research works have been focused on the preparation of gold nanoparticles/PVA/carbon black composite film and the fabrication of humidity sensor chips. Performance of as-fabricated humidity sensor devices has been investigated and compared. In this work, the Au NPs are added to a highly plasticized polymer film doped with electrically conductive carbon black particles. As the film is exposed in the water vapor and its structural conformation changes, the Au NPs and carbon black particles would be redistributed, thereby changing the electrical resistance of the device. Humidity sensor chips have been fabricated using the Au NPs/polymer/carbon black composite film with the pixels defined through screen printer or chip writer. By converting the signals into a recorder, the changes of humidity can be tracked over the chip. The success of the research not only prepares novel humidity sensitive materials, but also provides promising applications in fabricating humidity sensor chips, which with low cost, reliable humidity detector other than those reported.