The component miscibility evolution during polymerization of the polybutadiene containing styrene solutions

In situ graft copolymerization of polystyrene (PS) on polybutadiene (PB) during polymerization of PB solution in styrene monomer was investigated to determine the performance of grafting process, chain structure of generated copolymers, and their effectiveness as compatibilizing agents for incompatible PS-rich and PB-rich phases. The amount of copolymers and their chain structures at different stages of polymerization were determined by gel permeation chromatography (GPC) curves of the reactive blends (taken directly from the reaction) and physical blends (physically prepared based on total composition of reactive blends). It was demonstrated that copolymer formation started from the early stage of polymerization and continued up to the phase inversion stage. In addition, PS grafting on PB occurred initially via single-chain attachment and then converted to a double-chain scenario later on. Compatibilizing efficiency of the copolymers was evaluated by Huggins coefficient (k _H) obtained by performing dilute solution viscometry (DSV) on samples taken at different stages of conversions. The effect of molecular weight of PB on the grafting process and the effectiveness of copolymers generated were also studied. It was found that while compatibilizing role of the copolymers produced from high molecular weight PB (HPB) increases as conversion goes further, the compatibilizing efficiency of the copolymers produced from low molecular weight PB (LPB) shows a very sharp variation in a small range of conversion. Plotting k _H of physical blends against weight fraction of PB molecules in solid content of the solutions (w _PB) showed negative deviation from mixture law with a W-like pattern containing two minima with a maximum in between. While a negative deviation was assumed as indication of immiscibility of the components, upward deviation at middle values of w _PB was attributed to molecular segregations that reduce the interface between the incompatible PS-rich and PB-rich phases.     

Effects of composition and sintering time on liquid phase sintered Co-Cu samples in microgravity

Twelve Co-Cu powder compact samples with different liquid volume fractions were processed during microgravity liquid phase sintering on a suborbital sounding rocket and three Space Shuttle missions. The processing times ranged from 2.5 minutes to 66 minutes. The samples exhibited dimension stability after sintering. Microstructural evolutions such as densification, dihedral angle, contact per grain and grain growth rates, indicated a dependency on Cu composition and sintering time. Grain growth analysis showed a diffusion-controlled grain growth mechanism. The diffusional layer was found in a microgravity processed 70vol%Co-Cu sample. A mechanism that explains the transient nature of this diffusion layer is proposed and used to explain the results at other processing times. Agglomeration and coalescence of particles were observed in this study, and the grain size distributions were in agreement with LSEM model, which incorporates the effect of higher solid volume fraction and particle coalescence. Analysis of the samples also revealed considerable pore formation and metamorphosis. Unlike the Fe-Cu samples, in which pore breakup was found, pore filling and coarsening dominate in all Co-Cu samples. The evolution of these parameters has been used to enhance the understanding of driving forces that contribute to the pore metamorphosis during liquid phase sintering in the Co-Cu system under microgravity.     

Influence of Ultrasonic Waves on the Processing of Cotton with Cationic Softener

In recent years, the textile industry has been forced to develop new technologies to reduce energy and water consumption. The use of ultrasound in textile wet processing is one solution to this problem. The aim of this work was to investigate the effects of ultrasonic energy on the processing of cotton with a cationic softener. For this purpose, cotton fabric was treated with a fatty acid amide derivative cationic softener in water using ultrasonic energy during treatment. The physical properties of the fabrics treated under different conditions are discussed. The results show that the treatment of fabrics with softeners in an ultrasound bath is more effective compared to conventional methods and that it enhances the physical properties of the cotton.     

Model Free Approach for Non-Isothermal Decomposition of Un-Irradiated and γ-Irradiated Silver Acetate: New Route for Synthesis of Ag(2)O Nanoparticles

Kinetic studies for the non-isothermal decomposition of unirradiated and γ-irradiated silver acetate with 10(3) kGy total γ-ray doses were carried out in air. The results showed that the decomposition proceeds in one major step in the temperature range of (180-270 °C) with the formation of Ag(2)O as solid residue. The non-isothermal data for un-irradiated and γ-irradiated silver acetate were analyzed using Flynn-Wall-Ozawa (FWO) and nonlinear Vyazovkin (VYZ) iso-conversional methods. These free models on the investigated data showed a systematic dependence of Ea on α indicating a simple decomposition process. No significant changes in the thermal decomposition behavior of silver acetate were recorded as a result of γ-irradiation. Calcinations of γ-irradiated silver acetate (CH(3)COOAg) at 200 °C for 2 hours only led to the formation of pure Ag(2)O mono-dispersed nanoparticles. X-ray diffraction, FTIR and SEM techniques were employed for characterization of the synthesized nanoparticles.     

Improvement of processing parameters by using processing aids during the linear low‐density polyethylene film blowing process

Polymer processing aids are used to improve processing properties in the polyethylene industry. These materials improve not only the physical and mechanical properties of the final products but also their processing properties. This paper studies some of the processing variables such as die pressure, melt temperature, masterbatch activity, and die gap by examining the functions of polymer processing aids and, last but not least, the effects on the film blowing process of two‐component processing aids containing a perfluorinated additive and polyoxyethylene. J. VINYL ADDIT. TECHNOL., 2010. © 2009 Society of Plastics Engineers     

Non-Intrusive Online Quality of Experience Assessment for Voice Communications

Recently user quality of experience (QoE) is employed in evaluating end user satisfaction in communications systems. Generally, current approaches for QoE assessment are obtrusive, laboratory based and offline. Estimation of user satisfaction in static manner based on mean opinion score is not directly related to instantaneous individual end user contentment. In this paper, based on correlations between user’s physiological signals and her/his feelings about the service quality, a non-intrusive and user centric QoE assessment system for voice communications is developed. The findings of this study indicate that the emotional patterns in response to the changes in channel quality can be adapted to estimate the level of satisfaction in a QoE assessment system in a live manner. Based on experimental results, two categories of users are identified: sensitive and insensitive towards quality degradations. The results indicate that for the sensitive users, our non-intrusive subjective quality assessment method outperforms ITU-T P.563 standard with respect to root mean square error; while, the results are much better among the insensitive users.     

Lyophilized insulin nanoparticles prepared from quaternized N-aryl derivatives of chitosan as a new strategy for oral delivery of insulin: in vitro,ex vivo and in vivo characterizations

Objective: The purpose of this research was the development, in vitro, ex vivo and in vivo characterization of lyophilized insulin nanoparticles prepared from quaternized N-aryl derivatives of chitosan.

Methods: Insulin nanoparticles were prepared from methylated N-(4-N,N-dimethylaminobenzyl), methylated N-(4 pyridinyl) and methylated N-(benzyl). Insulin nanoparticles containing non-modified chitosan and also trimethyl chiotsan (TMC) were also prepared as control. The effects of the freeze-drying process on physico-chemical properties of nanoparticles were investigated. The release of insulin from the nanoparticles was studied in vitro. The mechanism of the release of insulin from different types of nanoparticles was determined using curve fitting. The secondary structure of the insulin released from the nanoparticles was analyzed using circular dichroism and the cell cytotoxicity of nanoparticles on a Caco-2 cell line was determined. Ex vivo studies were performed on excised rat jejunum using Frantz diffusion cells. In vivo studies were performed on diabetic male Wistar rats and blood glucose level and insulin serum concentration were determined.

Results: Optimized nanoparticles with proper physico-chemical properties were obtained. The lyophilization process was found to cause a decrease in zeta potential and an increase in PdI as well as and a decrease in entrapment efficiency (EE%) and loading efficiency (LE%) but conservation in size of nanoparticles. Atomic force microscopy (AFM) images showed non-aggregated, stable and spherical to sub-spherical nanoparticles. The in vitro release study revealed higher release rates for lyophilized compared to non-lyophilized nanoparticles. Cytotoxicity studies on Caco-2 cells revealed no significant cytotoxicity for prepared nanoparticles after 3-h post-incubation but did show the concentration-dependent cytotoxicity after 24?h. The percentage of cumulative insulin determined from ex vivo studies was significantly higher in nanoparticles prepared from quaternized aromatic derivatives of chitosan. In vivo data showed significantly higher insulin intestinal absorption in nanoparticles prepared from methylated N-(4-N, N-dimethylaminobenzyl) chitosan nanoparticles compared to trimethyl chitosan.

Conclusion: These data obtained demonstrated that as the result of optimized physico-chemical properties, drug release rate, cytotoxicity profile, ex vivo permeation enhancement and increased in vivo absorption, nanoparticles prepared from N-aryl derivatives of chitosan can be considered as valuable method for the oral delivery of insulin.     

Structural and optical properties of Co-doped ZnS nanoparticles synthesized by a capping agent

Cobalt-doped Zinc sulfide (ZnS) nanoparticles were prepared by a simple chemical method using alkyl hydroxyl ethyl dimethyl ammonium chloride (YH) as capping agent. The structural and optical properties of prepared cobalt-doped ZnS nanoparticles have been characterized. X-ray diffraction patterns and transmission electron microscope images reveal pure cubic ZnS phase with size of about 5–2 nm for all cobalt-doped ZnS nanoparticles. The lattice constant of the samples decreases slightly by the introduction of Co²⁺ The absorption edge of the ZnS:Co²⁺ nanoparticles is blue-shifted as compared with that of bulk ZnS, indicating the quantum confinement effect. The photoluminescence emission band exhibits a blue shift for Co-doped ZnS nanoparticles as compared to the ZnS nanoparticles.     

利用上下文转移实现移动IPv6上的IMS无缝切换

Mobility support for the next generation IPv6 networks has been one of the recent research issues due to the growing demand for wireless services over internet. In the other hand, 3GPP has introduced IP Multimedia Subsystem as the next generation IP based infrastructure for wireless and wired multimedia services. In this paper we present two context transfer mechanisms based on predictive and reactive schemes, to support seamless handover in IMS over Mobile IPv6. Those schemes reduce handover latency by transferring appropriate session ＇information between the old and the new access networks. Moreover, we present two methods for QoS parameters negotiations to preserve service quality along the mobile user movement path. The performances of the proposed mechanisms are evaluated by simulations.