Advanced Materials Research Vols. 236-238

Abstract: A novel SiO₂ hierarchical nanostructure standing on carbon nanowires is synthesized by using the hydrothermal method without any metallic catalysts. Its surface morphology, microstructure and composition are characterized by scanning electron microscopy, high-resolution transmission electron microscope and energy-dispersive spectroscope, respectively. The results show that this new nanostructure is consisted of core-shell-branches C@SiO₂/SiO₂. The cores are the single-crystalline carbon nanowire, and the shells and branches are the amorphous SiO₂. Growth mechanisms are discussed.

Abstract: High filtration efficiency of nanofibrous membrane has been proved in air filtration area, but, in addition to filtration efficiency, pressure drop is another important characteristic of fibrous filter. Because pressure-drop is related to energy wastage of filtration, it’s necessary to study. While there are not enough studies dedicated to pressure-drop of nanofibrous membrane filters. Here, different thickness PVA nanofibrous membranes were made by electrospinning, and they deposited on cotton scaffolds to form nanofibrous filter samples. Through testing these samples, we found as thickness of nanofibrous membrane increased, pressure-drop rose almost linearly, while filtration efficiency presented a different change trend. When thickness of nanofibrous membrane reaching a point, filtration efficiency attained extreme limit, even if increasing thickness nanofibrous membrane, filtration efficiency only rose limitedly, but pressure-drop still increased rapidly. At the same time, we found despite the thickness of nanofibrous membrane was thinner than conventional fibrous filter, pressure-drop of nanofibrous filter was obviously higher than conventional fibrous filter. So it’s remarkable phenomena. Through theoretical analysis and simulation, the causation of high pressure-drop of nanofibrous filter was discussed and provided. Decreasing diameter of fiber caused resistance performance change. It’s necessary to carry on a further research.

Abstract: Alginate/silica composite beads of mm-size for biomedical applications were prepared from water glass and sodium alginate via a simple sol-gel route. They kept their original shapes when soaked in the phosphate solution of lower pH. In this case, faint calcium phosphate peaks were observed in X-ray diffraction. Peaks corresponding to phosphate group were also found in FT-IR. Apatite was obtained on the surface of beads made with calcium chloride after soaking in phosphate solution while monetite was formed on the surface of beads made with calcium nitrate.

Abstract: The magnetic MFe₂O₄ (M=Co, Ni) nanoparticles are synthesized using a hydrothermal synthesis method in ethylene glycol (EG) solution. Their morphologies, structures, surface properties and magnetism are characterized by field emission scanning electron microscopy (FE-SEM), powder X-ray diffraction (XRD), fourier transform infrared (FTIR) absorption spectra, and vibrating sample magnetometer (VSM), respectively. The nickel ferrite and the cobalt ferrite samples are nearly spherical and homogeneous nanoparticles with average size range of about 90 nm (NiFe₂O₄) and 30 nm (CoFe₂O₄). XRD patterns confirm that the NiFe₂O₄ samples belong to the cubic structure and the CoFe₂O₄ samples are the rhombohedral structure. The NiFe₂O₄ nanoparticles are superparamagnetic at room temperature, while the CoFe₂O₄ nanoparticles are sub-ferromagnetic at room temperature and possess higher saturation magnetization.

Abstract: Tissue engineering involves the use of living cells and cell scaffolds to develop biological substitutes for tissue replacements, it is one of promising ways for rehabilitation and reconstruction functional tissue and organs. In order to engineer substitutes for tissue replacements, cell scaffolds with specific shape and pore structure are required. A novel “elastic porogen/pressure filtration technique” was put forward and studied firstly in this paper to overcome the disadvantages of the existed techniques for cell scaffold fabrication. The properties of elastic porogen (deformation ratio, water solubility, appearance and dimension) and pore structure of scaffolds were studied, respectively. The experimental results demonstrated that the scaffolds with well defined pore structure can be formed through this novel technique, and the pore shape and sizes as well as size of openings between pores could be manual controlled conveniently. The pore structure and morphology of scaffolds were satisfied to the requirements of tissue engineering, which suggested that elastic porogen/pressure filtration technique was an ideal cell scaffold forming technique.

Abstract: The Bombyx mori silk fibroin microspheres with controllable size were prepared by electrostatic spraying and freeze-drying method. The effects of solution concentration, voltage and flow rate on the sphere size were discussed. The morphology of microspheres was observed by scanning electron microscopy (SEM). The influence of ethanol treatment on the molecular conformation of silk fibroin microspheres was investigated by XRD and FT-IR spectra. The results indicated that the silk fibroin microspheres with diameter in range of 117-363 μm were spherical in shape, and there were plenty of pores both on the surface and in the interior of the microspheres. The sphere size increased with the rising of silk fibroin solution concentration and flow rate, while decreased as the voltage enhanced. The conformation of silk fibroin microspheres changed from random coil to silk II structure after ethanol treatment.

Abstract: We present a novel method to synthesize mesoporous nickel siliceous coated on CNTs with larger hole based on the mesoporous silica coated on CNTs, the pore size of mesoporous silica coated on CNTs was enlarged to 7.8 nm from 2.72 nm. Compared to others’ work, our method is low cost, simple and high efficiency. And more importantly, this method shows great potential in applying other type of mesoporous materials such as SBA-15 etc.

Abstract: A bioactive Si-Ca-P system (designated 58S) wet gel was prepared via a sol-gel method. The wet gel was reacted continuously in 0.25M K₂HPO₄ solution with a starting pH value of 9.0 at 37 °C for different time. The structural and compositional changes resulting from the conversion reaction were characterized using X-ray diffraction, scanning electron microscopy, Fourier transform infrared spectroscopy and inductive coupled plasma spectroscopy. The results indicated that the induction period for the CDHA nucleation on the surface of the 58S bioactive wet gel was about 3 days. The conversion mechanism of the products was also discussed.

Abstract: A novel compound N-benzoyl-N＇-(4-chlorobenzamido) thiourea was prepared from benzoyl isothiocyanate which was obtained from benzoyl chloride and potassium thiocyanate, and 4-chlorobenzoyl hydrazine which was obtained from ethyl 4-chlorobenzoate and hydrazine hydrate. IR, ¹H NMR, ¹³C NMR and elemental analysis were utilized to determine the structure of the thiourea. The biological tests indicated that the target compound had antibacterial activity against bacillus subtilis and taphylo-coccus aurers. Meanwhile, the thermal stability was investigated by thermogrativity（TG） and differential thermogrativity (DTG). The results demonstrated there was one weight-loss in the thermal decomposition process. The thermal kinetics equation obtained describing the thermal decomposition process was expressed as .

Abstract: BiOI nanolamellas and BiSI nanowires were synthesized using Bi(NO₃)₃·5H₂O, (NH₂)₂CS and I₂ as reactants in the solvothermal process with ethanol as the system media. The as-prepared samples were characterized by X-ray powder diffraction (XRD), scanning electronic microscopy (SEM), Energy-Dispersive X-ray Spectrometer (EDS). The competitive growth of BiOI and BiSI were investigated by changing the quantity of (NH₂)₂CS. A possible reaction mechanism was proposed.