大豆分离蛋白与明胶蛋白复合膜的制备与性能研究

以大豆分离蛋白为基质,添加明胶蛋白,用溶液铸膜法制备复合膜.研究了成膜液的溶液性能;复合膜的各种性能,包括表观性能、力学性能、阻隔性能.通过扫描电子显微镜观察了膜的微观结构.结果表明,当明胶含量为30%(质量分数)左右,两种蛋白的相容性最佳,复合膜的各项性能达到较佳值,拉伸强度达到31.59MPa,断裂伸长率达到65.96%,并且对氧气和水都有良好的阻隔性.     

Development and characterization of coated-microparticles based on whey protein/alginate using the Encapsulator device

The aim of this study is to prepare whey protein (WP)-based microparticles (MP) using the Encapsulator^® device. The viscosity dependence of the extrusion device required to mix WP with a food-grade and less viscous polymer. Mixed WP/ALG MP were obtained with the optimized WP/alginate (ALG) ratio (62/38). These particles were further coated with WP or ALG using non-traumatic and solvent-free coating process developed in this study. Size and morphology of coated and uncoated MP were determined. Then, swelling and degradation (WP release) of formulations were investigated in pH 1.2 and 7.5 buffers and in simulated gastric and intestinal fluids (SGF, SIF) and compared to pure ALG and pure WP particle behaviours. At pH 1.2, pure ALG shrank and pure WP swelled, whereas the sizes of mixed WP/ALG matrix were stable. In SGF, WP/ALG MP resisted to pepsin degradation compare to pure WP particles due to ALG shrinkage which limited pepsin diffusion within particles. Coating addition with WP or ALG slowed down pepsin degradation. At pH 7.5, WP/ALG particles were rapidly degraded due to ALG sensitivity but the addition of a WP coating limited effectively the swelling and the degradation of MP. In SIF, pancreatin accelerated MP degradation but ALG-coated MP exhibited interesting robustness. These results confirmed the interest and the feasibility to produce coated WP-based MP which could be a potential orally controlled release drug delivery system.     

Physicochemical properties of soy protein isolate/carboxymethyl cellulose blend films crosslinked by Maillard reactions: Color, transparency and heat-sealing ability

Soy protein isolate (SPI) films have many potential applications in the biomaterial field as surgical dressings for burns, films for reduction of wound inflammation, and facial masks. The appearance and the sealing ability are important physicochemical properties that greatly influence consumer acceptance of such protein-based films. The aim of the present work was to investigate the chemical structure and the physical properties associated with color, transparency and heat-sealing ability for SPI/carboxymethyl cellulose (CMC) blend films prepared by solution casting, with weight proportions 90/10, 80/20, 70/30 and 60/40. Fourier transform infra-red (FTIR) and solid-state ¹³C nuclear magnetic resonance (NMR) spectra confirmed that Maillard reactions occurred between SPI and CMC. The Hunter color value (L, a, b) and transparency of films were affected by varying the proportions of SPI and CMC. With increasing degree of crosslinking of SPI and CMC, the yellow color of the films was diluted and transparency was improved. Peel strength and tensile strength measurements showed that the Maillard reactions had the main effect of enhancing the heat-sealing ability above the melting temperature. These results indicated that the structure and properties of SPI-based films could be modified and improved by blending with CMC.     

大豆分离蛋白可食膜的制备及微波处理对性能的影响

制备了大豆分离蛋白可食性膜.为了提高大豆分离蛋白膜的性能,通过微波进行处理,考察微波对蛋白膜性能影响.结果表明:由于微波处理作用,蛋白膜机械性能增加显著,蛋白膜的阻水性能也得到提高.通过溶胀实验进一步考察蛋白膜交联程度,结果表明:微波处理大豆分离蛋白可食性膜,交联程度提高.     

大豆分离蛋白与小麦面筋蛋白共混的可食性复合包装膜研究

采用正交实验方法制备加入丙酸钙的大豆分离蛋白(SPI)与小麦面筋蛋白(WGP)复合薄膜,从力学性能、透水性、透氧性理化指标方面来比较蛋白质复合膜性能的优劣,结果发现,SPI-WGP复合膜性能比较优异,从中找出最优化的水平组合.     

Modeling flow properties of fine dry powders using particle morphological properties and its effects on geometry of fly ash evacuation hoppers

This paper results from an ongoing effort to correlate the physical properties of powders at a fundamental level with their bulk behavior. Cohesion and unconfined yield stress are the measure of inter-particle forces of attraction in the bulk powder. The existing model for cohesion does not include important bulk properties, such as particle size distribution, tapped density, and prevailing applied stress. In the present paper, flow properties of 25 bulk solids (different cement and fly ash samples) have been evaluated using a ring shear tester and the products have been characterized according to their flowabilities. Models for cohesion and unconfined yield strength have been developed in this study by taking into account the effects of particle size distribution, tapped bulk density and pre-shear stress. The newly developed models have provided good fit to the experimental data. The effect of these flow properties on the design of hoppers have been investigated for fly ash samples collected from seven consecutive electrostatic precipitator (ESP) hoppers of a coal fired thermal power station. The results show that fly ash from the rear end ESP hopper would require higher amount of opening size compared to the first or second field of ESP to ensure proper mass flow condition is achieved at all the ESP hoppers.     

A review on selective laser sintering/melting (SLS/SLM) of aluminium alloy powders: Processing,microstructure, and properties

Manufacturing businesses aiming to deliver their new customised products more quickly and gain more consumer markets for their products will increasingly employ selective laser sintering/melting (SLS/SLM) for fabricating high quality, low cost, repeatable, and reliable aluminium alloy powdered parts for automotive, aerospace, and aircraft applications. However, aluminium powder is known to be uniquely bedevilled with the tenacious surface oxide film which is difficult to avoid during SLS/SLM processing. The tenacity of the surface oxide film inhibits metallurgical bonding across the layers during SLS/SLM processing and this consequently leads to initiation of spheroidisation by Marangoni convection. Due to the paucity of publications on SLS/SLM processing of aluminium alloy powders, we review the current state of research and progress from different perspectives of the SLS/SLM, powder metallurgy (P/M) sintering, and pulsed electric current sintering (PECS) of ferrous, non-ferrous alloys, and composite powders as well as laser welding of aluminium alloys in order to provide a basis for follow-on-research that leads to the development of high productivity, SLS/SLM processing of aluminium alloy powders. Moreover, both P/M sintering and PECS of aluminium alloys are evaluated and related to the SLS process with a view to gaining useful insights especially in the aspects of liquid phase sintering (LPS) of aluminium alloys; application of LPS to SLS process; alloying effect in disrupting the surface oxide film of aluminium alloys; and designing of aluminium alloy suitable for the SLS/SLM process. Thereafter, SLS/SLM parameters, powder properties, and different types of lasers with their effects on the processing and densification of aluminium alloys are considered. The microstructure and metallurgical defects associated with SLS/SLM processed parts are also elucidated by highlighting the mechanism of their formation, the main influencing factors, and the remedial measures. Mechanical properties such as hardness, tensile, and fatigue strength of SLS/SLM processed parts are reported. The final part of this paper summarises findings from this review and outlines the trend for future research in the SLS/SLM processing of aluminium alloy powders.     

Comparative analysis of oxide phase formation and its effects on electrical properties of SiO2/InSb metal-oxide-semiconductor structures

We report on the changes in the interfacial phases between SiO₂ and InSb caused by various deposition temperatures and heat treatments. X-ray photoelectron spectroscopy (XPS) and Raman spectroscopy were used to evaluate the relative amount of each phase present at the interface. The effect of interfacial phases on the electrical properties of SiO₂/InSb metal-oxide-semiconductor (MOS) structures was investigated by capacitance-voltage (C-V) measurements. The amount of both In and Sb oxides increased with the deposition temperature. The amount of interfacial In oxide was larger for all samples, regardless of the deposition and annealing temperatures and times. In particular, the annealed samples contained less than half the amount of Sb oxide compared with the as-deposited samples, indicating a strong interfacial reaction between Sb oxide and the InSb substrate during annealing. The interface trap density sharply increased for deposition temperatures above 240 °C. The C-V measurements and Raman spectroscopy indicated that elemental Sb accumulation due to the interfacial reaction of Sb oxide with InSb substrate was responsible for the increased interfacial trap densities in these SiO₂/InSb MOS structures.     

The effects of preparation conditions on the structural and up-conversion properties of NaYF4:Yb, Er nano powders

The NaYF₄:Yb³⁺, Er³⁺ powders were prepared by a co-precipitation method. The relationship between the phase ratio of cubic to hexagonal phase and the emission intensity ratio of red to green was investigated. This concluded that the cubic phase dominantly contributed to the red emission, while the green emission was mainly ascribed to the hexagonal phase. The effects of Al³⁺ doping on UC emission were investigated first. The red emission intensity of the cubic phase was drastically enhanced when 10 mol% Al was added.