Effect of Water Fraction on Rheological Properties of Waxy Crude Oil Emulsions

This article discusses the effect of water fraction on the rheological properties of waxy crude oil emulsions including gel point, yield stress, viscosity, and thixotropy. The experimental results reveal that the rheological behaviors of the w/o emulsion samples all intensify with the increase of water volume fraction within 60%. Of more significance is that a correlation for w/o emulsions between yield stress and water volume fraction is put forward with an average relative error of 6.75%. In addition, some mainstream viscosity prediction models of w/o emulsions are evaluated, and Elgibaly model is the best-fit for the emulsions in this study.     

Effect of a topical formulation containing Calophyllum brasiliense Camb. extract on cutaneous wound healing in rats

This study evaluated the wound healing effects of topical application of an emulsion containing the HPLC-standardised extract from Calophyllum brasiliense Cambess (Clusiaceae) leaves in rats. The macroscopic analysis demonstrated that the wounds treated with the C. brasiliense emulsion healed earlier than the wounds treated with emulsion base and Dersani®. The percentage of wound healing in the group treated with the C. brasiliense emulsion was significantly higher than in the other groups at 7 and 14 days. On day 14, the animals treated with the C. brasiliense emulsion exhibited a 90.67% reduction of the wound areas. The histological evaluation revealed that on day 21, the group treated with the C. brasiliense emulsion exhibited a significant increase in fibroblasts compared with the other groups. Thus, the C. brasiliense emulsion had healing properties in the topical treatment of wounds and accelerated the healing process.     

ESR and calculations on electronic structure of phenalenyl and phenalenyl derivative radicals

Calculations on electronic structure of the perinaphthenyl radical and phenalenyl derivative radicals responsible for the composition of the ESR spectrum of marine diesel under heating were performed to obtain support for the experimental ESR results. The parameters calculated were the hyperfine coupling constants (A), which were then used for comparison with the experimental data. The energy‐minimized structures were obtained using the density functional theory method. In all cases, the symmetry system was taken into account in theoretical calculations. The differences between experimental and theoretical values were below 7% for nearest hydrogens in molecules, named hyperfine coupling constant A (first neighbors) and 18% for farthest hydrogens atoms named hyperfine coupling constants A′ (second neighbors), for all structures analyzed. Copyright © 2014 John Wiley & Sons, Ltd.     

费谢尔判别法鉴别原油/燃料油

以多环芳烃作为变量,建立了原油、燃料油属性鉴别的费谢尔判别法。分别测定了来自不同国家和地区的26个原油样品和25个燃料油样品中8种多环芳烃的含量,并将它们作为判别变量。借助SPSS 16.0进行费谢尔判别分析,建立费谢尔判别函数。将未知样品的判别变量值代入后,可以快速地得知样品的类别。结果表明,以多环芳烃作为判别变量进行原油、燃料油费谢尔判别快速而准确。     

活性炭吸附-火焰原子吸收光谱法测定粗硒中的金

建立了活性炭吸附-火焰原子吸收光谱法测定粗硒中金量的分析方法。讨论了称样量、溶样条件和活性炭的灰化程度对金量测定的影响,并且对火焰原子吸收光谱法与火试金法测定粗硒中的金量做了比较。火焰原子吸收光谱法和火试金法测定的相对标准偏差分别为1.3%~5.9%和0.91%~7.8%;加标回收率分别为93.1%~100.7%和94.8%~102.2%。结果表明,方法有较好的精密度和准确度,并且具有较强的实用性。     

Non-isothermal kinetic analysis and feasibilty study of medium grade crude oil field

In this research, non-isothermal kinetics and feasibility study of medium grade crude oil is studied in the presence of a limestone matrix. Experiments were performed at a heating rate of 10°C min⁻¹, whereas the air flow rate was kept constant at 50 mL min⁻¹ in the temperature range of 20 to 600°C (DSC) and 20 to 900°C (TG). In combustion with air, three distinct reaction regions were identified in all crude oil/limestone mixtures, known as low temperature oxidation (LTO), fuel deposition (FD) and high temperature oxidation (HTO). The activation energy values were in the order of 5–9 kJ mol⁻¹ in LTO region and 189–229 kJ mol⁻¹ in HTO region. It was concluded that the medium grade crude oil field was not feasible for a self-sustained combustion process.     

Aqueous extracts of Agave sisalana boles have prebiotic potential

Abstract

This work aimed at evaluating the prebiotic potential of the aqueous extract and crude polysaccharides from Agave sisalana boles by an in vitro screening. Crude polysaccharides were obtained from the aqueous bole extract by precipitation with acetone and resuspension in water. The liquid extract and the polysaccharide solution were then spray dried and submitted to thermal analysis and quantification of metabolites. Prebiotic activity was checked on probiotic strains belonging to the Lactobacillus genus using inulin, fructo-oligosaccharides, fructose and glucose as positive controls. The powder of A. sisalana bole extract, which has recently been identified as a rich source of inulin, exhibited higher potential of fermentation compared with crude polysaccharides.     

含蜡原油胶凝过程特性研究

利用RS75流变仪在小振幅振荡剪切的模式下分别研究了3种不同历史条件下含蜡原油的胶凝过程, 同时通过偏光显微镜观察了不同降温速率条件下原油中的蜡晶形貌. 结果表明, 在静态降温条件下, 降温速率越大, 原油胶凝的温度越低, 原油形成的胶凝结构越弱; 并且降温速率越大, 原油在恒温静止过程中, 结构随时间恢复的速率越大, 恢复至平衡所需时间越长, 但最终的平衡结构却越弱; 在同样的降温速率下, 原油低温胶凝结构随着降温过程中剪切作用的增强而减弱, 但当历史剪切速率超过一定数值时, 原油的胶凝结构将基本不再继续变化; 在同样的历史剪切速率下, 降温速率越大, 原油在低温(31 ℃)静止初始的储能模量越小, 但最终的平衡结构却越强.     

Molecularly Engineered 6FDA-Based Polyimide Membranes for Sour Natural Gas Separation

Glassy polyimide membranes are attractive for industrial applications in sour natural gas purification. Unfortunately, the lack of fundamental understanding of relationships between polyimide chemical structures and their gas transport properties in the presence of H₂S constrains the design and engineering of advanced membranes for such challenging applications. Herein, 6FDA-based polyimide membranes with engineered structures were synthesized to tune their CO₂/CH₄ and H₂S/CH₄ separation performances and plasticization properties. Under ternary mixed sour gas feeds, controlling polymer chain packing and plasticization tendency of such polyimide membranes via tuning the chemical structures were found to offer better combined H₂S and CO₂ removal efficiency compared to conventional polymers. Fundamental insights into structure–property relationships of 6FDA-based polyimide membranes observed in this study offer guidance for next generation membranes for sour natural gas separation.     

Determination of volatile and non-volatile nickel and vanadium compounds in crude oil using electrothermal atomic absorption spectrometry after oil fractionation into saturates, aromatics, resins and asphaltenes

In recent work, it has been shown that electrothermal atomic absorption spectrometry (ET AAS) can be used to differentiate between volatile and non-volatile nickel and vanadium compounds in crude oil. In the present work, the distribution of these two groups of compounds over different fractions of crude oil was investigated. For this purpose two crude oil samples were separated in two steps: firstly, the asphaltenes were precipitated with n-heptane, and secondly, the maltenes were loaded on a silica column and eluted with solvents of increasing polarity. The four fractions of maltenes eluted from silica column were: F1, saturated and light aromatics; F2, polyaromatics; F3, resins; and F4, polar compounds. Fractions F1 and F2 were further investigated using gas chromatography, and all fractions were characterized by CHN analysis, confirming the increase of aromatics in the fractions 2, 3, 4 and asphaltenes. For the determination of Ni and V by ET AAS, oil-in-water emulsions were prepared. The speciation analysis was carried out measuring without chemical modifier (stable compounds) and with 20 μg palladium (total Ni and V) and the volatile fraction was calculated by difference. The limits of detection were 0.02 μg g⁻¹ and 0.06 μg g⁻¹, for Ni and V, respectively, based on an emulsion of 2 g of oil in 10 mL. The volatile species of Ni and V were associated with fractions F3 and F4, while only thermally stable Ni and V was precipitated in part together with the asphaltenes.