Advanced Materials Research Vols. 148-149

Abstract: A low-temperature precursor sulfuration route has been established to prepare metal sulfides with different nanostructures during the synthesis of nickel sulfide. The advantages of the low-temperature precursor sulfuration route were testified by the synthesis of different metal sulfides ( lead sulfide, zinc sulfide and cobalt sulfide). It offers a novel path to the preparation of other metal sulfides.

Abstract: Four kinds of solutions were prepared by dissolving cellulose acetate in dichloromethane, formic acid, acetic acid and trifluoroacetic acid respectively, and then were electrospun into fibers. The solutions were characterized for their viscosity and conductivity using rotary viscosimeter and conductivity meter, respectively. The morphology and performance of the electrospun CA fibers were investigated by scanning electron microscopy (SEM), digital microscope and X-ray diffraction (XRD). Results showed that the important factors determining the electro-spinnability of the CA solutions were boiling point, viscosity and conductivity of the resulting solutions. 8% CA spinning solution with trifluoroacetic acid as solvent had good spinnability, and the average diameter reached 236nm; the obtained fibers were mainly amorphous, but characterized for good mechanical properties.

Abstract: Cu-Zn alloy was prepared by high energy ball milling of elemental copper and zinc, With the Simoloyer attrition mill the particle around 10µm with good particle-size distributions can be made in 100 min. Through the analysis by TG-DTA, XRD, SEM, the results show that Cu-Zn alloys can be produced by ball milling without the formation of oxide even milling in the air atmosphere and subsequent heat treatment at 350°C, it indicated that the formation of the oxide can be avoided during ball milling by adding Al.

Abstract: Carbon nanotubes (CNTs) of different diameter were synthesized by chemical vapor deposition using LaNi5 alloy of micrometer magnitude as catalyst. High-power ultrasonic grinder was employed to disperse CNTs for various time. CNTs with different dispersion levels were obtained and their impacts on the performance of CNTs supercapacitor electrode were researched as well. Constant current charge-discharge, Cycle Votammetry was employed to study the supercapacitors properties of carbon nanotubes. And the results showed that the specific capacitance of CNTs electrode without ultrasonic was 95.88F/g. However CNTs electrode has preferable electrochemistry properties with 16 hours ultrasonic dispersion, CNTs diameter about 30-50nm and well dispersibility: the specific capacitance had enhanced 69.9%, as high as 162.88F/g.

Abstract: Control of the water level in the drum of the boiler system is a critical operation consideration, because asymmetric dynamics of water level measured leads to measuring errors. This phenomenon is testified by field data from a 400t/h drum boiler with natural circulation in a power plant of China. Some equations are developed and several related factors are focused on, and two of which become critical ones accounting for asymmetry of measured value. With the study of structure of distribution pipes in drum, it is found that feed-water flows distributed on the opposite ends of drum are obviously asymmetric, where measurement systems are positioned. When more feed-water is supplied at one end of drum, the rate of steam in water and water temperature become lower, and measured level get higher. Through the simulation, the important factors for asymmetric of water level are found out, which is necessary to minimize the measuring errosrs.

Abstract: As a drug delivery carrier, a novel pH/temperature sensitive bead (pTSB) with core-shelled structure from poly(N-acryloylglycine) (PAG), copoly(N-acryloylglycine methyl este and N-acryloylglycine ethyl ester) was prepared by two steps. In pH=7.4 phosphate buffer solution (PBS), the cumulative release amount of indomethacin loaded in the pTSB was about 60.1 % within 500 mins, but this value only reached to 22.3 % in pH=2.1 PBS. The release behaviors of indomethacin from pTSB also exhibited a remarkable dependence on PAG content in the core. Additionally, the release rate of indomethacin was much faster at 18 oC than that at 37 oC due to the temperature sensitivity of poly(N-acryloylglycinates). The experimental results indicate that pTSB seems to have a potential application in the drug release system controlled via pH or temperature in the biomedical fields.

Abstract: Silk fibroin/cellulose acetate blend Nanofibrous membranes were prepared by electro- spinning and their performances were evaluated as a heavy metal ion adsorbent. The electrospun nanofibrous membranes were comprised of randomly oriented ultra-fine fibers of 100-600nm diameters. As a result of field emission electron microscope (FEEM), compared with pure nanofibrous membranes, the anti-felting shrinkage of SF/CA blend nanofibrous membranes with 20% CA content was markedly improved after treatment with 100% ethanol. Metal ion adsorption test was performed with Cu2+ as a model heavy metal ion in a stock solution. The pure SF nanofibrous membranes exhibited high metal ion capacities compared with that pure CA nanofibrous membrane. Especially, the SF/CA blend nanofibrous membranes had an exceptional performance for the adsorption of metal ions, and the maximum milligrams per gram of metal ions adsorbed reached 22.8mg/g for Cu2+. This indicated that SF and CA had synergetic effect.

Abstract: In the paper a high-pressure stirring solvothermal method with ethylenediamine as a solvent was used to prepare CIGS powders. The impact factors of reaction temperature and holding time on product-phase and morphology were investigated. The increasing reaction temperature make a important impact on the phase of product and the increasing holding time has much effect on the product morphology. CIGS particles (8-10 μm) were successfully synthesized at reaction temperatures in the range of 200-250 °C for different holding times.

Abstract: Monodispersed ZnO micro/nanocrystals with various morphologies were successfully prepared via a simple solution route at low temperature. The products were characterized by means of scanning electron microscopy (SEM), X-ray diffraction (XRD), high-resolution transmission electron microscope (HRTEM), and selected area electron diffraction (SAED). Results suggest a close relationship between the morphology of ZnO and the external factors. Possible mechanisms for the controllable synthesis of ZnO particles are preliminarily discussed.

Abstract: In this research, NaA zeolite samples were synthesized from aluminosilicate solution through hydrothermal method. The effects of different parameters such as the SiO2/Al2O3, OH-/Si and H2O/Na2O molar ratios of the initial gel solution, crystallization time and temperature on the crystallinity and morphology of the synthesized zeolites were investigated. The final products were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and laser particle size analyzer. The experiment results indicated that the SiO2/Al2O3 molar ratio had influence on morphology and size of the synthesized zeolites, the optimum range of SiO2/Al2O3 molar ratio for synthesizing NaA zeolite was 1.5-2. Alkalinity (OH-/Si and H2O/Na2O molar ratio) had a significant effect on particle sizes of the synthesized zeolites, the higher the alkalinity, the smaller the crystal particle size. In addition, it was found that crystallization temperature during hydrothermal treatment played an important role in reducing the over all reaction time. The crystallization time had effect on the crystallinity of the synthesized zeolites. Finally, the optimum synthesis parameters can be proposed in order to synthesize NaA zeolite with desirable particle size, crystallinity and morphology.