日本花柏心材精油的抑菌活性分析

日本花柏心材精油的抑菌活性实验结果表明:下部年轮5~10年心材和中部心材精油均对金黄色葡萄球菌和大肠杆菌有抑制作用,中部心材精油对金黄色葡萄球菌的抑菌圈直径为 14.86 mm,对大肠杆菌的抑菌圈直径为 14.56 mm;气相色谱-质谱分析结果表明日本花柏心材下部年轮5~10年心材和中部心材精油挥发性组分主要由醇类和萜烯类化合物组成,中部心材精油含有较高的柏木醇(26.52%)。柏木醇是具有潜在开发价值的抑菌活性化合物。     

毛竹和日本花柏精油化学成分研究

利用气相色谱-质谱法分析了毛竹和日本花柏精油的活性化学成分,结果表明:毛竹精油主要化学成分为柏木醇(44.03%)、罗汉柏烯(13.88%)、花侧柏烯(11.48%)、马兜铃烯(4.82%)和α-杜松醇(3.66%);日本花柏精油主要化学成分为δ-杜松醇(35.04%)、α-杜松醇(14.40%)、epi-双环倍半水芹烯(10.08%)、可巴烯(9.84%)、8-丙氧基-香松烷(7.84%)、卡达烯(3.60%)和γ-桉叶醇(3.41%)。α-杜松醇、罗汉柏烯和马兜铃烯是毛竹和日本花柏精油的共有化学成分,柏木醇和α-杜松醇是具有开发潜力的活性化学成分。     

无规共聚聚丙烯正己烷提取物的性能及影响因素研究

采用气相质谱色谱分析仪(PGC-MS)和凝胶色谱分析仪(GPC)分析了无规共聚聚丙烯正己烷提取物的组成和性能,并对影响正己烷提取物的因素进行了分析。结果表明,正己烷提取物由摩尔质量在4 000～20 000 g/mol范围内的乙丙共聚物和主、辅抗氧剂构成,乙烯含量是影响正己烷提取物的关键因素,其他聚合条件如氢气加入量、双环管反应器的乙烯进料比、助催化剂与外给电子体的质量比(AL/DO)等也影响正己烷提取物。     

傅里叶变换近红外光谱法应用于聚乙烯树脂的正己烷提取物分析

采用偏最小二乘法(PLS),建立了傅里叶变换近红外漫反射光谱法检测聚乙烯树脂正己烷提取物的数学模型。分析过程选择了最佳光谱预处理方法、谱区范围及主因子数,并使用内部交叉验证对模型进行验证。实验结果表明,当选择最小-最大归一化的光谱预处理方法,谱区范围7 501.8～6 097.9 cm-1和5 025.6～4 597.5 cm-1,主因子数8时定量模型的准确度最好,决定系数(R2)和均方差(RMSECV)分别为0.988和0.416,近红外测定值与标准方法测定值基本一致。对297种牌号共1 251个进口聚乙烯树脂正己烷提取物项目的普查结果表明,聚乙烯树脂正己烷提取物项目的总体安全性较低,属于进口聚乙烯需重点关注的安全卫生项目。     

多种天然提取物将在日本禁售

2005年8月，日本将有38种非合成食品添加剂从现有食品添加剂目录中删除。与此同时，含有这38种食品添加剂的食品在日本境内也将禁止销售，此举主要是为了确保食品安全。     

正己烷分析方法的研究

气相色谱法具有分离效能高,分析速度快等特点,文章建立了气相色谱分析正己烷的方法,确立了色谱的最佳分离条件,该方法精密度高,对正己烷的三个样品进行分析,取6次平行测定结果,标准偏差分别为0.092,0.017,0.061。相对标准偏差(RSD)分别为0.435,0.027,0.114。准确性好,样品加标回收率在96.09%~101.16%之间。     

气相色谱法测定正己烷中的烯烃

采用气相色谱分析仪,建立了正己烷中烯烃含量的测定方法,同时考察了该方法的检测限、精密度。结果表明,该方法测定正己烷中烯烃含量为0.004%(质量百分含量)时,其信噪比仍在3以上。该方法的相对标准偏差为1.5%~14.1%。     

工业正己烷精制生产药用级正己烷

对工业正己烷装置进行扩能及精制工艺改造,使工业正己烷产品的生产能力从1900t/a增至3000t/a;精制后高纯正己烷产品含量达到97%,苯含量小于1mg/kg,硫含量小于1mg/kg,达到药用级。改造充分利用原有装置、设施,节省大量资金,具有很好的经济效益。     

正己烷中微量水分的测定

有机物中所含的微量水分会对化工生产造成很大影响,使用WS-2型微量水测定仪测定正己烷中的微量水分,能检出5×10^-6以上的水分含量,结果稳定性好,精确度高。     

Analysis and Fate of Lipophilic Extractives in Sulphite Pulps

Abstract

One of the major requirements of sulphite pulps, particularly those used in the manufacture of dissolving grades, is that their extractives content must not exceed certain levels, as specified by the customer. Since these levels are generally very low, the accuracy and reproducibility of extractives measurements can be poor, which in turn can lead to disagreements between pulp suppliers and their customers. In an effort to improve the reliability of extractives measurements, we have evaluated several methods for the determination of lipophilic extractives in sulphite pulps, using Soxhlet and Soxtec solvent extraction and various modes of drying the extracts including hot plate, infrared lamp, and freeze drying. Analysis of the extracts by size exclusion chromatography showed that a significant portion of the extracts was polymerized during the production process. Lipophilic extractives from ammonium sulphite pulps contain more polymerized matter than the extractives from the magnesium process.     

Hydrogen Production in the Radiolysis of Dodecane and Hexane

The yields of molecular hydrogen, H₂, have been measured in the radiolysis of dodecane and hexane following radiolysis by γ-rays and a variety of heavy ions. Measured yields with γ-rays are found to be slightly higher than literature values and decrease by about 25% on aeration of the sample. Increasing the linear energy transfer (LET) from γ-rays to radiolysis with protons results in a decrease of H₂ yields by about 15% due to the increased importance of second-order H atom combination reactions. A further increase in LET results in a slight increase in H₂ yields.     

Hexane sorption in oilseed meals

Sorptional equilibrium of hexane in oilseed meals was studied as a function of temperature, solvent activity, and oil content. A dynamic technique was implemented based on gravimetric measurements with a Cahn electrobalance. Sorption and desorption isotherms of hexane in sunflower and soybean meals were determined at atmospheric pressure in the range 50 to 95°C. The equilibrium was reached faster during the adsorption process and at high hexane activities. The final equilibrium was not influenced by particle size and sample geometry. Hexane sorption is strongly dependent on temperature, meal composition and oil content, and the effect of hysteresis is negligible. Hexane is mainly retained by adsorption on the cell structure, absorption in the residual oil, and capillary condensation in the meal pores. Experimental equilibrium data were fitted to the GAB equation, and the parameters were determined by nonlinear regression analysis. This model represents satisfactorily the sorption behavior in a wide range of conditions.     

LLDPE装置己烷系统的环境治理改进

兰州石化LLDPE装置的含氮气己烷回收系统由于历史原因无法有效回收,造成周围环境污染较为严重,给邻近各区的动火施工作业造成极大的危害.经过对该系统进行改造治理可以大大减少周边作业环境污染,同时可以节约能源,降低装置物耗.     

微库仑法测定己烷中微量水

己烷中微量水的测定采用微库仑法,本文提出了在不同改变测试步骤的情况下,将用氮气进样改为直接进样,两法所得结果十分吻合,本文就如何提高分析的准确作了讨论。     

己烷的工业分离方法

介绍了己烷的原料来源,重点介绍了其工业分离方法。     

食品接触材料、高分子材料、橡胶制品中提出物的测定条件的探讨

根据接触的食品类型,选择合适的溶剂,在回流温度下初回流提取7h后,再次回流提取2h,提取液经蒸发、干燥和恒重,得到的残渣的质量,除以试样的表面积,即为提取物的含量。     

Rapid Prediction of Different Wood Species Extractives and Lignin Content Using Near Infrared Spectroscopy

Abstract

The feasibility of using Fourier transform near infrared spectroscopy (FT-NIR) to rapidly determine the lignin and extractive content of various wood species (including softwoods and hardwoods) was investigated. Partial Least Square regression analyses were performed to describe the relationships between the data sets of wet laboratory chemical data and the FT-NIR spectra. The selection of relevant wavenumbers combined with the appropriate data pre-processing methods produced satisfactory prediction models. The test statistics (R² , RMSECV, RMSEP, RPD) improved compared with the models over the wave number range 7500 cm^?1 to 4000 cm^?1. Automatic selection was superior to manual selection. The predicted lignin and extractive content models, using the full cross-validation in the appropriate wave number ranges (in cm^?1) of 5450.1 to 4246.7, 6102.1 to 4597.7, 6252.4 to 4246.7, and 6252.4 to 6098.1 using the spectral data preprocessing methods of the straight-line subtraction, minimum–maximum normalization, and first derivative + vector normalization, were established. The high R² values were 0.9838, 0.9809, and 0.9625, respectively. The low RMSECV values were 0.425%, 0.452%, and 0.185%, respectively. RPD values were 7.86, 7.25, and 5.17, respectively. Predictions were very good, with R² of 0.9775, 0.9751, and 0.9521; RMSEP of 0.418%, 0.403%, and 0.206%; and RPD of 6.78, 6.7, and 4.57 for the lignin, 1% sodium hydroxide extractive, and ethanol-benzene extractive models, respectively.     

云南松树皮提取物的性能研究

以乙酸乙酯-水为溶剂对云南松树皮进行提取。对提取产物的溶解性、紫外吸收光谱、热稳定性、光稳定性和抗氧化性进行了研究。结果表明,云南松树皮提取物具有较好的水溶性,最大吸收波长为 280 nm,当温度≤60℃时,对热稳定,具有一定的耐光性;对食用油脂具有良好的抗氧化作用。