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151.
Ahmed Abd El-Fattah Mohamad Nageeb Hassan Ahmad Rashad Mona Marei Sherif Kandil 《International Journal of Polymer Analysis and Characterization》2020,25(5):362-373
Abstract An injectable composite hydrogel composed of polyvinyl alcohol (PVA) and bioactive glass (BG) particles were synthesized by a physical crosslinking approach. The morphology, mechanical properties, and viscoelasticity of the PVA/BG composite hydrogel were characterized. Scanning electronic microscopy (SEM) showed uniform and homogeneous distribution of BG particles throughout the composite hydrogel. The incorporation of 2.5?wt% of BG particles in the composite hydrogel formulations, enhanced the static compressive strength and static elastic modulus by 325% and 150%, respectively. The storage molds (G′) was greater than the loss modules (G′′) at all the frequency range studied, which revealed a self-standing elastic composite hydrogel with a smooth injectability. The PVA/BG composite hydrogel was also implanted subcutaneously in the dorsal region of adult male rats. After 4?weeks of implantation, no inflammatory cells were seen within and around the implant, which indicated that the composite hydrogel was biocompatible. The properties of the synthesized injectable PVA/BG composite hydrogel demonstrate its capability toward bone regeneration. 相似文献
152.
A.A. Ahmed I.M. Youssof A.F. Abbas O. Abou Eleinen 《Journal of Sol-Gel Science and Technology》1998,13(1-3):753-756
The chemical durability of lead glass tumblers (24% PbO) in a 4% (v/v) acetic acid solution before and after coating with sol-gel derived SiO2 films was assessed to determine the extent of reduction in Pb-leaching that can be achieved. It was found that by coating the internal surface of the glass tumblers with 1 ml of 10% TEOS solutions at 100°C and densifying the coating formed at 500°C for 1 h, it was possible to reduce Pb-leaching to about one quarter of that of the uncoated glass. 相似文献
153.
Xi-yan Liu Dong Qiu Mei-li Guo Zhen-zhong Yang 《高分子科学》2005,(5):561-566
Sub-micron sized phenolic epoxy resin waterborne particles were prepared by phase inversion emulsification. Micro-phase separation occurred during the curing process at high temperature. The as-prepared samples possessed one glass transition temperature (Tg) and two exothermal processes during DSC heating scannings. After being thermally treated above the exothermal peak temperature, they possessed two glass transition temperatures with the disappearance of exothermal peaks, whilst a core/shell structure was formed. This was likely related with the outward diffusion of reactive oligomers to the outer layer of particles. 相似文献
154.
Two types of commercial glass fibers were subjected to attack in strongly basic KOH solutions. The resulting leach solutions were analysed for Na, Ca, and Si. This showed that the corrosion process attacks the fibers incongruently. Although there are some distinct differences in the performance of these fibers, to a first approximation both types behave similarly. Further, the fibers were depth profiled using a recently developed SNMS technique for fiber in-depth analysis. This showed that both types of fibers behave in a quite dissimilar manner. The fibers were weathered already without any treatment. Although both fibers show alkali ion exchange and network splitting processes, on one of the fiber layers enriched in SiO2, Fe2O3, and CaO are formed by a redeposition process from the leach solution.Dedicated to Professor Dr. rer. nat. Dr. h.c. Hubertus Nickel on the occasion of his 65th birthday 相似文献
155.
Quan HAN Hong Tao YAN* Zhen Jie QIAN Department of Chemistry Northwest University Xi抋n 《中国化学快报》2002,13(12)
Thermal lens spectrometry (TLS) is an excellent tool for trace analysis1. TLS allows the detection of absorbances of 10-7~10-8, concentration of ≈ 10-11 mol稬-1 and the analysis of 10-15 L volumes with ≈10-2 absorbing molecules2. Kinetic analysis is playing an increasingly important part in modern analytical chemistry. Therefore, TLS shows much promise in combination with kinetic analysis. However, there are few data on TLS applications in kinetic analysis method so far3~4. A ne… 相似文献
156.
Exfoliated polystyrene (PS)/laponite nanocomposites were prepared successfully. The characteristic doo1 diffraction peak of organo-laponite disappeared in the XRD patterns of nanocomposites, indicating that the laponite layers were exfoliated and the ordered crystal structure of laponite was destroyed because of the styrene polymerization. TEM observations showed that the exfoliated laponite primary particles were dispersed randomly in the PS matrix with lateral dimensions from 1 nm to 10 rim. SEM results showed that the PS/laponite nanocomposite particles were almost monodispersed spheres with the size of about 120 rim. Because of the interaction between PS and laponite nanolayers, the nanocomposites exhibited higher thermal stability and glass transition temperature when compared to pure PS. 相似文献
157.
Summary Thermally stimulated depolarization currents (TSDC) of atactic (a), syndiotactic (s) and isotactic (i) PMMA and mixtures ofs- andi-PMMA were measured. In pure tactic PMMA, TSDC peak was obtained at a temperature corresponding to the glass transition temperature of each PMMA. TSDC of mixtures isolated as precipitates from 1/1 and 1/2 (i/sweight ratio) mixed solutions showed a peak which can be attributed to the glass transition temperature of the stereocomplex. TSDC of original l/1 mixture showed two peaks which are ascribed to the glass transition temperature of residual i-PMMA and the stereocomplex. The results suggests that stereocomplex formation occurs ini/s weight ratio of 1/2 independent of the way of preparation.With 9 figures and 1 table 相似文献
158.
Most of the common classes of organic compounds chromatograph normally on Superoxes. There is no tailing or adverse effect from excessively different activity different activity coefficients. Superoxes are therefore universal phases for gas chromatography. This is also expressed by a wide useful temperature range from ~50° to ~300°. High MW Superox-4 has a MAOT about 20° higher than the lower MW Superox-0.1. Several applications illustrating the versatility of Superox phases in (GC)2 are presented. 相似文献
159.
氯酚(CP)化合物被广泛应用于木材防腐、金属防锈及杀虫剂等,因其毒性大、难降解,对环境造成严重污染[1,2]。目前用于CP的光催化降解的TiO2粉体悬浮体系,催化剂不易回收利用。本文采用Sol Gel法制备的负载型TiO2纳米粒子膜作为光催化剂,对4 CP进行了降解实验研究。同时应用XRD法表征了不同实验条件下薄膜中TiO2的晶相结构和粒度,考察了不同层数TiO2膜的光催化活性,并对4 CP的降解条件及反应动力学特征进行了探讨。1 实验部分1.1 玻璃负载TiO2膜的制备与表征[3-5]按照钛酸四丁酯∶无水乙醇∶水=3∶12∶… 相似文献
160.
P. Torline G. du Plessis N. Schnautz J. C. Thompson 《Journal of separation science》1979,2(10):613-616
A detailed method for the routine preparation of glass capillary columns is presented. The method consists of coating a glass tube with quartz powder prior to pulling the tube into a capillary. The inner surface of the capillary consists of an even distribution of quartz particles fused to the walls. This surface has been found readily deactivated by standard procedures and ideal for the preparation of thick-film glass capillary columns. The method has been thoroughly tested in two independent laboratories to ensure that the procedures described are reproducible. 相似文献