静电纺动物蛋白纳米纤维研究进展

为拓展静电纺纳米纤维的应用领域,拓宽静电纺丝工艺的材料来源,对国内外近期静电纺动物蛋白纳米纤维的研究进展进行了综述。针对目前静电纺丝工艺中有机溶剂使蛋白质变性的问题,介绍了几种取代有机溶剂的方法,并对这些方法的优缺点进行对比,分析认为水溶性聚合物代替有机溶剂的方法更有利于蛋白纳米纤维在生物医药领域应用;讨论了交联改性及共混改性对静电纺动物蛋白纳米纤维力学性能的影响,对静电纺胶原蛋白纳米纤维在生物医药领域的应用进行了总结;最后针对利用静电纺丝技术制备动物蛋白纳米纤维亟待解决的问题以及未来的发展方向进行了展望。     

蓝莓-蓝靛果复合冻干粉贮藏期品质及加工特性

研究蓝莓-蓝靛果复合果粉在不同贮藏温度（4、25、37 ℃）及相对湿度（relative humidity,Hr）（43%、75%、95%）下贮藏12 周内玻璃化转变温度（Tg）、亮度、抗氧化能力及抗氧化物质含量的变化规律,并对其贮藏过程中的粉体行为进行表征。结果表明：相比于其他贮藏条件,25 ℃、Hr 43%（Tg降低4.62 ℃）和4 ℃、Hr 75%（水分质量分数上升4.2%）条件下复合果粉贮藏12 周后在基本理化指标方面表现较佳;在对抗氧化物质含量和抗氧化能力影响方面,随贮藏时间延长,不同条件处理组总酚和总黄酮含量以及抗氧化能力下降;在对花色苷含量影响方面,与贮藏前相比,25 ℃、Hr 43%条件下贮藏12 周后6 种花色苷及总花色苷降解量最低（总花色苷含量（72.56 mg/g）降低了23.92%）,4 ℃、Hr 75 %条件下贮藏12 周后总花色苷含量保留率较高;在加工特性方面,25 ℃、Hr 43%及4 ℃、Hr 75 %条件下贮藏12 周后样品的流动性保持较好。综上表明4 ℃、Hr 75%和25 ℃、Hr 43%的环境利于复合果粉贮藏。     

A simple one‐step synthesis and polymerization of plant oil triglyceride iodo isocyanates

In this study, a novel and simple route for the synthesis of the iodine isocyanate (INCO) adduct of soybean oil triglycerides is described. Soybean oil iodo isocyanate (ISONCO) was synthesized by the reaction of iodine isocyanate and soybean oil at room temperature. ISONCO was then polymerized with polyols, such as, castor oil, pentamethylene glycol, and glycerol to give the corresponding polyurethanes and with polyamines, such as, ethylene diamine, hexamethylene diamine, and triethylene tetramine to give corresponding polyureas. The structures of the monomer and the polymers were determined by FTIR and ¹H‐NMR analyses. Thermal properties of the polymers were determined by DSC and TGA. Thermal degradation of the polyurethanes started at 150°C. Stability of the polyureas was higher than polyurethanes. Almost all polymers showed a T_g around ?50°C. The mechanical properties of the polymers were determined by tensile tests. Among the polymers synthesized, castor oil polyurethane showed the highest elongation at break and the lowest tensile strength of 140 KPa. The highest tensile strength of 900 KPa was observed in the pentamethylene glycol polyurethanes. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Carbon nanotube/boehmite-derived alumina ceramics obtained by hydrothermal synthesis and spark plasma sintering (SPS)

Preparation, structure and properties of hydrothermally treated carbon nanotube/boehmite (CNT/γ-AlOOH) and densification with spark plasma sintering of Al₂O₃ and CNT/Al₂O₃ nanocomposites were investigated. Hydrothermal synthesis was employed to produce CNT/boehmite from an aluminum acetate (Al(OH)(C₂H₃O₂)₂) and multiwall-CNTs mixture (200 °C/2 h.). TEM observations revealed that the size of the cubic shape boehmite particles lies around 40 nm and the presence of the interaction between surface functionalized CNTs and boehmite particles acts to form ‘nanocomposite particles’. Al₂O₃ and CNT/Al₂O₃ compact bodies were formed by means of spark plasma sintering (SPS) at 1600 °C for 5 min using an applied pressure of 50MPa resulting in the formation of stable α-Al₂O₃ phase and CNT–alumina compacts with nearly full density. It was also found that CNTs tend to locate along the alumina grain boundaries and therefore inhibit the grain coarsening and cause inter-granular fracture mode. The DC conductivity measurements reveal that the DC conductivity of CNT/Al₂O₃ is 10^?4 S/m which indicate that there is a 4 orders of magnitude increase in conductivity compared to monolithic Al₂O₃. The results of the microhardness tests indicate a slight increase in hardness for CNT/Al₂O₃ (28.35 GPa for Al₂O₃ and 28.57 GPa for CNT/Al₂O₃).     

Separation of gas and organic/water mixtures by MFI type zeolite membranes synthesized in a flow system

MFI type zeolite membranes were synthesized in a recirculating flow system at 95 °C where the synthesis solution was flown over the tubular α-alumina supports. The performance of the membranes for the separation of binary gas mixtures and alcohol/water liquid mixtures was investigated. A membrane synthesized by two consecutive synthesis steps had a separation selectivity of 15 and 11 for equimolar mixtures of n-C₄H₁₀/CH₄ and n-C₄H₁₀/N₂ at 200 °C, respectively. The membrane selectively permeated large n-C₄H₁₀ over small CH₄ and N₂, suggesting that the separation is essentially adsorption-based and the membrane has few nonselective intercrystalline pores. The selectivities in the pervaporation separation of 5% ethanol/95% water mixture were 43 and 23 with permeate fluxes of 0.2 and 1.9 kg/m² h at 25 and 85 °C, respectively. The separation performance of membranes showed that MFI type membranes prepared in a recirculating flow system can be used both in the separation of gas and liquid mixtures.     

Polymeric absorbent for water sorption based on chemically crosslinked poly (acrylamide/2-acrylamido-2-methyl-1-propanesulfonic acid sodium salt) hydrogels

Summary Swelling equilibrium of polyelectrolyte copolymer gels containing of acrylamide (AAm) and 2-acrylamido-2-methyl-1-propanesulfonic acid sodium salt (AMPS) have been studied as a function of copolymer composition. AAm/AMPS hydrogels were prepared by free radical solution polymerization in aqueous solution of AAm with AMPS as anionic comonomer and two multifunctional crosslinkers such as ethylene glycol dimethacrylate (EGDMA) and trimethylolpropane triacrylate (TMPTA). Swelling experiments were performed in water at 25 °C, gravimetrically. The influence of AMPS content in hydrogels was examined. Swelling of AAm/AMPS hydrogels was increased up to 1018% (for containing 2% AMPS and crosslinked by EGDMA) 15246% (for containing 8% AMPS and crosslinked by TMPTA), while AAm hydrogels swelled up to 804% (crosslinked by TMPTA)–770% (crosslinked by EGDMA). The values of equilibrium water content of the hydrogels are 0.8851–0.9935. Diffusion behavior was investigated. Water diffusion into hydrogels was found to be non-Fickian in character.     

Synthesis and characterization of a Zr‐containing silicate‐based epoxy‐functional polymer nanocomposite system

As a continuation of efforts to explore the potential of certain types of polymer nanocomposites to be successful candidates as dental restoration/adhesion materials, a Zr‐containing and organically modified silicate‐based material system with epoxy functionality was prepared by use of a sol–gel synthesis method, and UV light‐ and visible light (VL)‐curing processes. Comparative influences of the synthesis and processing parameters on the mechanical, thermal, and microstructural/nanostructural properties of the system were detailed. Zr‐containing species proved to more effectively catalyze the epoxy polymerization/crosslinking reactions than those containing Ti. Incorporation of Zr into the nanocomposite network led to significantly advanced mechanical properties. An elastic (Young's) modulus value of 23 MPa was achieved. The system with relatively high Zr content was successfully obtained, which also had higher thermal stability. Overall observations and results suggested that Zr content, and the UV light‐ or VL‐curing process could be capitalized on to modify the structure, and to improve the final properties of these material systems, which indicated a prospective opportunity for this material system to be utilized in dental restoration/adhesion applications. POLYM. ENG. SCI., 55:792–798, 2015. © 2014 Society of Plastics Engineers     

Determination of nutrients and volatile constituents of Agaricus bisporus (brown) at different stages

BACKGROUND: The physical properties, proximate composition, mineral and vitamin contents, and estimated volatile components of Portobello mushroom, Agaricus bisporus (brown), were analyzed in three flushes and at two different harvest times. The results showed different trends in the flushes and harvest terms studied. RESULTS: The mean values of texture, diameter, and protein of the harvested produce were 1.78–1.97 kg mm^?2, 4.67–5.02 cm, and 4.18–3.31% wet weight basis (wb), respectively. The mean Zn, Fe, P, Mg, K, Na, and Ca contents of both harvests (mg kg^?1 wb) were 8.15–7.07, 7.40–7.96, 1180.93–1038.69, 88.05–76.29, 213.29–238.82, 2652.0–2500.89, and 534.2–554.80, respectively. In terms of vitamin C, folic acid, thiamin, riboflavin, and niacin, the mean contents (mg kg^?1 wb) were 6.75–3.97, 0.09–0.08, 0.085–0.09, 0.27–0.29, and 3.62–2.94, respectively. The estimated volatile components comprised 18‐ or 16‐carbon compounds such as octadecanoic acid, hexadecanoic acid derivatives, and other important volatiles like dl‐limonene, n‐nonane, benzendicarboxylic acid, and cis‐linoleic acid esters. CONCLUSION: Nutritive contents and estimated volatiles of Portobello mushroom were evaluated in detail at different stages. Copyright © 2009 Society of Chemical Industry     

Myoglobin adsorption onto poly(glycidyl methacrylate) microbeads with surface functionalized iminodiacetic acid

In this study, poly(glycidyl methacrylate) [PGMA] microbeads with surface modified iminodiacetic acid (IDA) were used for myoglobin (Mb) adsorption from buffer solutions at different pHs and ionic strengths in a packed-bed column. Attenuated Total Reflectance Fourier Transformed Infrared (ATR-FTIR) spectroscopy and scanning electron microscopy (SEM) measurements before and after the adsorption process confirmed the structural stability of adsorbed Mb. The effects of initial concentration, flow-rate, pH and ionic strength on the adsorption were investigated. The results showed that the maximum amount of protein was adsorbed at a pH 7.0, which is the protein isoelectric point. The adsorption is rationalized in terms of local electrostatic forces acting between the protein and the IDA modified PGMA surface as well as hydrophobic interactions close to the protein isoelectric point, whereas at low pH the global changes give rise to protein–protein repulsion and at high pH protein-support material repulsion.