一些聚合物对中相微乳液物性的影响

研究了水解聚丙烯酰胺、黄原胶和木质素磺酸盐对中相微乳液相体积、粘度和界面张力的影响。实验结果表明: 含有聚丙烯酰胺时,中相微乳液的相态、增溶参数、中相与下相间界面张力及中相粘度均无明显变化。生物聚合物对中相微乳液的物理性质影响也不大。木质素磺酸盐则对微乳液的形成产生明显影响: 随着木质素磺酸盐浓度的增大,微乳液由中相转变为上相,相应的物理参数亦有变化。     

Synthesis of Hydroxypropyl Guar Gum by Phase Transfer Catalysis

HGG (Hydroxypropyl guar gum) was synthesized by phase transfer catalysis for the first time. The effects of alkalinity, phase transfer catalyst, etherification, pH value, temperature,reaction time and stirring speed were investigated. An optimal synthetic reaction technology was established, namely, dose of guar gum is 100 g, propylene oxide 40-50 g, HTAC (hexadecyl trimethyl ammonium chloride ) 1.3-1.7 g, pH value 10-10.5, temperature 45-50~C, and reaction time 3-4 hours. The result shows that the improved HGG has high viscosity. Its dissolution speed, content of insoluble residue, colloid light transparency and stability are apparently superior to guar flour.     

HS/GC-MS法分析胶基型嚼烟中的挥发性香味物质

运用静态顶空气相色谱-质谱法对22个胶基型嚼烟样品中的挥发性香味物质进行分析,并采用质谱数据库对挥发性香味物质进行定性分析。对顶空分析条件以及GC-MS条件进行了优化,提高了挥发性香味物质的测定灵敏度;对峰面积归一化结果大于0.1%的化合物进行定性分析,通过匹配度限定(≥85%)确认了65种挥发性香味物质;最后对样品进行了相似性分析和聚类分析。结果表明:22个胶基型嚼烟样品中的香味物质主要有酯类(18个化合物)、烯烃类(16个化合物)、醇类(9个化合物)、醛类(8个化合物)、酮类(7个化合物)、酚类(1个化合物)、酸类(1个化合物)、呋喃类(2个化合物)、烷烃类(2个化合物)、硫醚类(1个化合物),共10类化合物;不同胶基型嚼烟样品的品牌识别度高,同时口味对品牌识别有一定的影响作用。方法为进一步开发胶基型嚼烟制品提供了理论基础和技术支持。     

Characterization of different double-emulsion formulations based on food-grade emulsifiers and stabilizers

This study focused on the preparation and characterization of water-in-oil-in-water (W1/O/W2)-type double emulsions designed by food-grade emulsifiers and stabilizers. The primary objective of this study was to compare different emulsion formulations in terms of droplet size, rheology, and stability and to reduce the amount of polyglycerol poliricinoleate (PGPR). To achieve these goals, PGPR and a PGPR–lecithin blend were utilized in the formation of the primary phase (W1/O), while varying concentrations of guar gum (GG) and gum tragacanth (GT) incorporated in the secondary water phase (W2). Shear thinning behavior was observed for all emulsion formulations. Sauter mean diameters of the emulsions prepared with PGPR as a hydrophobic emulsifier ranged between 30?µm and 75?µm, while those prepared with the PGPR–lecithin blend varied between 25?µm and 85?µm based on the first day’s measurements. In emulsions with the PGPR–lecithin blend, the smallest droplet size was obtained when the GG–GT blend was incorporated in the external aqueous phase. Moreover, GG–GT blends had high consistency coefficients and high apparent viscosity values. It was also observed that PGPR–lecithin containing emulsions were more stable.     

Biosynthesis of palladium nanoparticles as a heterogeneous and reusable nanocatalyst for reduction of nitroarenes and Suzuki coupling reactions

A facile and green route for the synthesis of palladium nanoparticles (Pd‐NPs) was developed utilizing non‐toxic and renewable natural green tea extract as the reducing, stabilizing and capping agent. The as‐prepared Pd‐NPs@Oak Gum catalyst was characterized using UV–visible spectroscopy, X‐ray diffraction, Fourier transform infrared spectroscopy, field emission scanning electron microscopy, transmission electron microscopy and energy dispersive X‐ray spectroscopy. The Pd‐NPs@Oak Gum catalyst could be used as an efficient and heterogeneous catalyst for Suzuki coupling reactions between phenylboronic acid and a range of aryl halides containing iodo, bromo and chloro moieties and also for the reduction of nitroarenes using sodium borohydride in an environmental friendly medium. Excellent yields of products were obtained with a wide range of substrates and the catalyst was recycled multiple times without any significant loss of its catalytic activity. Copyright © 2016 John Wiley & Sons, Ltd.     

An eco-friendly synthesis,characterization and antibacterial applications of novel almond gum – poly(acrylamide) based hydrogel silver nanocomposite

Polysaccharide based semi interpenetrating hydrogel (SIH) networks of cross-linked poly(acrylamide) was synthesised through an redox initiating free radical polymerization utilizing almond gum as a grafting backbone, N,N′– methylenebisacrylamide (MBA) as the cross-linker and ammonium persulphate (APS) – N,N,N′,N′-tetramethyl ethylenediamine (TEMED) as the redox initiator pair. Silver ions were introduced into the hydrogel matrix and silver nanoparticles of invariable size were developed insitu of the swollen hydrogel by the reduction of silver ions (Ag⁺) using azadirachta indica (neem) leaf extract. The prepared hydrogel - silver nanocomposite (HSN) was characterized by UV–visible diffused reflectance spectroscopy (DRS), fourier transform infrared spectroscopy (FT-IR), high resolution scanning electron microscopy (HR-SEM), energy dispersive X-ray analysis (EDX) and thermogravimetric analysis (TGA). The influence of pH on the swelling behavior of HSN was studied and the antibacterial activity of the developed nanocomposite was evaluated.     

Effect of ultrasonic treatment on the stability and release of selenium-containing peptide TSeMMM-encapsulated nanoparticles in vitro and in vivo

Rice selenium-containing peptide TSeMMM (T) with immunomodulatory functions was isolated from selenium-enriched rice protein hydrolysates. However, its biological activity is difficult to be protected in complex digestive environments. In this study, T was encapsulated within zein and gum arabian (GA) through ultrasound treatment to improve its bioactivity and bioavailability. The zein@T/GA nanoparticles were formed using ultrasonic treatment at 360 W for 5 min with a 59.9% T-encapsulation efficiency. In vitro digestion showed that the cumulative release rate of zein@T/GA nanoparticles reached a maximum of 80.69% after 6 h. In addition, short-term animal studies revealed that the nanoparticles had an effect on the levels of tissue glutathione and improved peptides’ oral bioavailability. Conclusively, these findings suggest that the ultrasonicated polysaccharide/protein system is suitable for encapsulating active small molecular peptides. Furthermore, it provides a novel foundation for studying the bioavailability of active substances in functional foods.     

Damping performance of Eucommia ulmoides gum

Eucommia ulmoides gum(EU gum),known as gutta percha in Southeast Asia,is a natural polymer with double characteristics of rubber and plastic.In present paper,tanδ-T curve and hysteresis loss(HL) were chosen to characterize its damping property.The results indicated that its tanδvalue would increase with rising of temperature when T>0℃and form another damping peak at 40-80℃besides T_g peak.This phenomenon resulted from meltage of crystals of EU gum could increase its damping property at ambient-high temperature.Its tanδvalue even exceeded those of conventional damping rubbers,such as nitrile-butadiene rubber(NBR) and chlorinated isobutene-isoprene rubber(CIIR).     

Preparation and characterization of oxidized sesbania gum and evaluation of its warp sizing performance for fine cotton yarns

Sesbania gum (SG) was oxidized by sodium hypochlorite. Resultant oxidized sesbania gum (OSG) was characterized by means of Fourier transformation infrared spectrometry, scanning electron microscopy, and high resolution transmission electron microscopy. The thermal stability of OSG was analyzed by means of thermal analysis and the apparent viscosity of its slurry was also measured by rotary viscometer. Moreover, the effect of OSG slurry as a warp sizing agent on the physico-mechanical properties of fine cotton yarns was investigated. It was found that fine cotton yarns sized with OSG had increased tensile strength and decreased elongation at break than the untreated ones. Besides, the fine cotton yarns treated with the OSG slurry had obviously decreased hairiness index and slightly increased abrasion resistance, and OSG slurry had good adhesion. In one word, as-synthesized OSG slurry may find promising application as a novel high-performance warp sizing agent for fine cotton yarns.     

微波消解-原子吸收光谱法测定瓜尔豆胶中的痕量铅

建立了微波消解-石墨炉原子吸收法测定瓜尔豆胶中铅的方法。探讨了样品的称样量及前处理条件、基体改进剂的选择以及仪器工作条件的优化。铅的线性范围为0～40.0μg/L,相关系数r=0.9996,方法的检出限为0.63μg/L,测定结果的相对标准偏差为1.32%～2.16%(n=6),加标回收率为90.3%～99.4%。该法准确、简单、灵敏度高,重现性好。