牛蒡提取物抑菌活性的研究

对牛蒡根茎和皮的水、50% 乙醇以及无水乙醇提取物的抑菌作用及其稳定性进行初步研究,结果表明：各种提取液对大肠杆菌、金黄色葡萄球菌、枯草芽孢杆菌、黑曲霉以及面包酵母菌均有一定的抑制作用,50% 乙醇提取液抑菌效果好于水提取液和无水乙醇提取液,且各种提取液中牛蒡皮的抑菌效果好于牛蒡根茎提取液,抑菌活性由大到小依次为金黄色葡萄球菌、枯草芽孢杆菌、大肠杆菌、黑曲霉菌、面包酵母。提取液在酸性条件下(pH3～5)抑菌效果较好,但高温(＞ 100℃)处理和紫外光长时间(≥ 5min)照射均可降低其抑菌活性。     

柚子皮提取物对C38的缓蚀作用

目的研究柚子皮提取物对C38钢在1 mol/L HCl中的缓蚀作用。方法通过索氏提取器从柚子皮中提取天然绿色缓蚀剂,进而与0.01 mol/L KI进行复配,采用失重法和电化学测试法分析柚子皮提取物的缓蚀作用机理。结果失重实验表明,柚子皮提取物对C38钢的缓蚀作用最高达93%,而与0.01mol/L KI复配使用后缓蚀效率最高达98%以上。同时表明其在碳钢表面的吸附符合Langmuir吸附等温式;Tafel极化曲线表明其能同时抑制碳钢腐蚀的阴、阳极过程;碳钢的阻抗值随着柚子皮提取物浓度的增加而增大。结论柚子皮提取物是很好的缓蚀剂,与卤素离子复配后效果更佳。     

陈皮的挥发性香气分析

为了深入探究陈皮的挥发性香气成分,采用溶剂辅助风味蒸发法（SAFE）提取陈皮中的挥发性成分,利用气相色谱-质谱联用仪（GC-MS）和气相色谱-嗅闻联用技术（GC-O）对陈皮和九制陈皮中的挥发性风味物质进行鉴定,结果共鉴定出93挥发性成分,46种香气活性物质。为了确定关键香气物质,采用香气提取物稀释分析法（AEDA）对两种陈皮的香气活性成分作进一步分析,结果显示：萜烯类、醇类和醛类化合物是主要的香气活性物质,其中柠檬烯、月桂烯是两者共有的关键香气成分。此外,1,4-二甲基-4-乙酰基-1-环己烯、橙花醇、香茅醛、肉豆蔻醛和α-甜橙醛是陈皮中的关键香气成分;香兰素、香芹酚、紫苏醇、芳樟醇、香芹酮和β-紫罗酮是九制陈皮中关键香气成分。通过对两种陈皮的关键性风味物质进行对比分析,确定出两种陈皮中对风味贡献较大的香气化合物及其差异组分,从而为陈皮类产品的开发提供理论支撑。     

Preparation and properties of environment-friendly acrylic latex laminating adhesives applied in plastic/plastic composite films

Acrylic latex laminating adhesives (ALLAs) were successfully prepared via a monomer-starved seeded semi-continuous emulsion polymerization with butyl acrylate (BA), methyl methacrylate (MMA), styrene (St), acrylamide (Am), and methacrylate glycidyl ether (GMA) as monomers. Impacts of GMA on the final latex, the dried latex films and the adhesive properties of ALLAs were investigated, respectively. The results indicated that the increase of GMA contents in the pre-emulsion feed has no apparent effect on the final latex average particle size and size distribution, while the gel contents, glass transition temperature (T_g) and water contact angle of the ALLAs gradually increased, and the molecular weight (M_n, M_w) obviously increased. Additionally, as the amount of GMA increased from 0 to 10?wt%, the maximum peel strength of the composite films reached 3.72 N/15mm with 5?wt% GMA contents. When heated to 65?°C, the peel strength of the composite films with 5?wt% of GMA can still maintain an acceptable peel strength (2.51 N/15mm) for application, showing excellent adhesive performance and heat resistance properties.     

高耐温性钢塑管材用热熔胶黏剂的制备及性能研究

以神华均聚聚丙烯（PP）为基体树脂,通过与聚烯烃弹性体（POE）共混反应挤出制备了高耐温性钢塑管材用热熔胶黏剂。研究了引发剂含量、接枝单体含量和PP/POE配比对热熔胶性能的影响,考察了自制热熔胶在实际应用中的耐温性能。结果表明,反应挤出制备的聚丙烯接枝马来酸酐(PP?g?MAH)基热熔胶综合性能优异,其剥离强度和100 %拉伸弹性回复率分别可达131.4 N/25 mm和65.5 %;高低温循环（-40~130 ℃）800次后自制热熔胶的剥离强度依然可以维持在122.2 N/25 mm,剥离失效率只有7.0 %,其耐温性明显优于选取的两个商业化牌号热熔胶。     

Surface modification of tetrafluoroethylene–hexafluoropropylene (FEP) copolymer by remote H2, N2, O2, and Ar plasmas

Tetrafluoroethylene–hexafluoropropylene (FEP) copolymer sheets were modified by remote H₂, N₂, O₂, and Ar plasmas, and the effects of the modification on adhesion between FEP sheets and copper metal were investigated. The four plasmas were able to modify the FEP surfaces' hydrophilicity. Defluorination and oxidation reactions on the FEP surfaces occurred with exposure to the plasma. The hydrophilic modification by H₂ plasma was best, followed by modification by O₂, Ar, and N₂ plasmas. The surface modification of FEP by all four remote plasmas was effective in improving adhesion with copper metal. The peel strength order of the FEP/Cu adhesive joints was H₂ plasma > Ar plasma > N₂ plasma > O₂ plasma. Mild surface modification is important for the adhesion improvement of FEP with Cu metal. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 83: 1258–1267, 2002     

CONVECTIVE DRYING OF AGRICULTURAL PRODUCTS. EFFECT OF CONTINUOUS AND STEPWISE CHANGE IN DRYING AIR TEMPERATURE

Samples of banana were dried in a two-stage heat pump dryer capable of producing stepwise control of the inlet drying air temperature while keeping absolute humidity constant. Two stepwise air temperature profiles were tested. The incremental temperature step change in temperature of the drying air about the mean air temperature of 30 °C was 5 °C. The total drying time for each temperature-time profile was about 300 minutes. The drying kinetics and color change of the products dried under these stepwise variation of the inlet air temperature were measured and compared with constant air temperature drying. The stepwise air temperature variation was found to yield better quality product in terms of color of the dried product. Further, it was found that by employing a step-down temperature profile, it was possible to reduce the drying time to reach the desired moisture content.     

Physicochemical properties and organoleptic aspects of ice cream enriched with microencapsulated pistachio peel extract

The purpose of this study was to produce a functional ice cream by the addition of microcapsules of pistachio peel extract (MPPE). Various properties of the resulting ice cream were investigated. By increasing the amount of MPPE the total phenolic content and antioxidant activity increased about 2.0‐ and 3.7‐fold, respectively, compared with the control sample. The rheological properties of the mixes were fitted by the Power Law model. All mixes showed non‐Newtonian pseudoplastic behaviour. By increasing the concentration of MPPE, the consistency coefficient (m), viscosity, and shear sensitivity were increased, but the flow behaviour index (n) decreased. The addition of MPPE to ice cream mixes improved the melting resistance, first dripping times and functional properties of ice cream such as antioxidant activity and total phenolic content. The results of the sensory analysis showed that the addition of MPPE had no significant effect on the overall acceptability of the product. Based on our findings, MPPE has the potential to be used as an added‐value ingredient in the ice cream industry to enhance the functional properties of their products.     

葡萄籽和葡萄皮清除自由基作用的研究

用化学发光法研究了葡萄籽和葡萄皮水提物对活性氧超氧阴离子自由基和羟自由基的清除作用,分光光度法研究了它们对１,１－二工本 基－２－苦肼基自由基的清清除作用。     

Natural compounds from Punica granatum peel as multiple stabilizers for polyethylene

Punica granatum peel extractive (PPE), a novel stabilizer of polyethylene, is investigated in this study. Oxidation onset temperature (OOT), carbonyl index (CI), melt flow rate (MFR), tensile strength, and elongation at break are used to characterize the effects of PPE, which are also compared with commercial antioxidant (Irganox 1010) with the presence of tetrakis (2,4-di-tert-butylphenol)[1,1-biphenyl]-4,4′-diylbisphosphite (PEPQ). Long-term and short-term aging results show that samples modified by PPE or Irganox 1010 (PE-PPE_0.12%-P and PE-1010_0.12%-P samples) have comparable CI value and stability of OOT. However, compared with PE-PPE_0.12%-P sample, much higher CI and larger change of MFR is detected for PE-1010_0.12%-P after UV irradiation and five extrusions. It suggests that PPE is better protector for PE against UV light and mechanical shear force. All results indicate that the effect of PPE in protecting PE is comparable or much better than Irganox 1010 and it can be used as multiple stabilizers for PE. Moreover, the stabilities of PE modified with PPE alone (PE-PPE_2%) is also investigated. Results show that PE-PPE_2% sample has good thermo-oxidative, UV and processing stabilities. All results reveal that PPE is a good candidate of PE stabilizer and it could avoid the usage of PEPQ in protecting PE.