Solvent fractionation of hard palm stearin to increase the concentration of tripalmitoylglycerol and dipalmitoyl-stearoyl-glycerol as substrates for synthesis of human milk fat substitute

This research aimed to produce triacylglycerols fraction rich in palmitic acid (PA) at the sn-2 position from hard palm stearin (HPS) through acetone fractionation. Fractionations were done at HPS-to-acetone ratios of 1:3, 1:5 and 1:7 (w/v) and at temperatures of 25, 30 and 35 °C for 3 h. Triacylglycerols with PA at the sn-2 position, such as tripalmitoylglycerol (PPP) and dipalmitoyl-stearoyl-glycerol (PPS), were concentrated in the solid fraction, obtained after separation by filtration. The optimal fractionation conditions were at a HPS-to-acetone ratio of 1:5 (w/v) and 30 °C. The total PPP and PPS content was more than 91%, with a corresponding yield of more than 59%. Triacylglycerols obtained were composed of more than 91% PA in which 88% were at the sn-2 position. Conclusively, the solvent fractionation is a suited alternative method for the preparation of triacylglycerols used for the enzymatic synthesis of 1,3-dioleoyl-2-palmitoylglycerol which is the main triacylglycerol for human milk fat substitute.     

丙酮低压一步法合成甲基异丁基酮催化剂体系研究进展

对丙酮低压一步法合成甲基异丁基酮所需要的催化剂体系及反失活机理进行了详尽的综述，并对近年来的研究工作进行了系统地分析与比较，提出了未来的研究方向。     

STUDY ON PERMEATION OF ACETONE/NITROGEN MIXED GAS THROUGH AL2O3 MICROPOROUS MEMBRANES: MOLECULAR DYNAMICS

In this work, by applying Materials Studio 2.2 software package, molecular dynamics (MD) was performed to investigate the dynamic processes of 1:4 acetone/nitrogen mixed gas permeating through different Al₂O₃ microporous membranes. Three systems were modeled by considering different box lengths, microporous sizes, and textures of Al₂O₃ membranes to compare different permeation behaviors. In each system, initial mixed gas contained 20 acetone molecules and 80 nitrogen molecules, and its density was set to 0.1 g/cm³. Analysis on the concentration profiles of nitrogen molecules (N2) and acetone molecules (Ace) in each system at different sampling times was implemented to discuss the permeation behaviors of smaller N2 and larger Ace. The results showed that adsorption and diffusion occurred synchronously but adsorption was dominant for acetone molecules and that the adsorption on the floor surface of the feed gas region more easily reached equilibrium (local equilibrium) than the diffusion and the adsorption on the ceiling of the initially vacuum region. Furthermore, for nitrogen, adsorption followed diffusion. Higher temperature is in favor of the enrichment of acetone on the floor surface of the feed gas region but against the adsorption of nitrogen. The adsorptive layer was found to be a double-layer with COMPASS force field and to be a monolayer with PCFF force field.     

Effect of the nature and structure of pillared clays in the catalytic behaviour of supported manganese oxide

In the present work, the complete oxidation of acetone has been studied over a series of supported manganese oxide catalysts on the unpillared and the Al- and Zr-pillared forms of two natural clays, a montmorillonite and a saponite. A significant influence of the clay supports characteristics on the catalytic performance has been found. The following order of improving catalytic performance is established with respect to the pillars composition: Al-pillared clays < unpillared clays < Zr-pillared clays.     

The Viscosity of cottonseed oil,fractionation solvents and their solutions

Cold fractionation of cottonseed oil is made difficult by the high viscosity of the oil. This study was aimed at demonstrating the effect of solvents on the viscosity of mixtures between 0°C and 25°C with a view to facilitating the fractionation of refined cottonseed oil. The solvents used were acetone, methylethylketone, methylisobutylketone, hexane and heptane. Measurements of viscosity were carried out by means of a capillary viscometer. The ratio of the viscosity of cottonseed oil to that of pure solvents is of the order of 300. The viscosities of solutions of various ratios of solvent to oil (1/3, 1/1, 3/1) are between those of cottonseed oil and the pure solvents. The effect of the solvent/oil ratio overrides that of solvent nature. The effect of solvent in reducing the viscosity of cottonseed oil is by descending order: acetone, hexane, methylethylketone, heptane, methylisobutylketone.     

镁铝复合氧化物催化剂气相法合成异佛尔酮

研究了镁铝复合氧化物存在下的丙酮综合合成异佛尔酮的常压气相反应以及催化剂的制备，考察了催化剂的组成和反应温度等对反应温度等对反应的影响，从而确定了较适于工业化投产的反应条件。     

WO3 nanocrystals: Synthesis and application in highly sensitive detection of acetone

WO₃ nanocrystals have been prepared by a sol-gel route and characterized by X-ray diffractometry, scanning electron microscopy, and transmission electron microscopy. The experimental results show that WO₃ nanocrystals have a high crystallographic quality and a good dispersivity. The particles’ sizes are in the range of 25-100 nm. The fabricated WO₃ nanocrystal-based sensors have an excellent sensitivity and selectivity to acetone, and display a rapid response and recovery characteristics. The developed sensors exhibit a detection limit down to 0.05 ppm at 300 °C, rendering a promising application in noninvasive diagnosis of diabetes. The response mechanism of the WO₃ nanocrystal sensor to low concentration of acetone has been discussed based on the depletion layer model.     

二丙酮醇生产工艺的改进

探讨了用强碱性阴离子交换树脂催化下合成了二丙酮醇的适宜工艺，选择了合适的工艺条件，反应周期短，催化剂寿命长，如，反应从催化剂上端进行，反应温度２０～２５℃。单程反应的最短时间为４ｈ，收率９２％，比重０．９３，折光率１．４２４０～１．４２４２产品质量与文献值相符，催化剂寿命大于１５０ｈ。     

Measurements of fuel mixture fraction oscillations of a turbulent jet non-premixed flame

This work describes new type of combustion instability for which the 3-way coupling between mixing, flame heat release, and acoustics is modified by local buoyancy effects. Measurements of fuel mixture fraction are made for a non-premixed jet flame in a combustion chamber to assess the dynamics of mixing under imposed acoustic oscillations (22-55 Hz). Infrared laser absorption and phase resolved acetone-planar laser induced fluorescence are used to measure the fuel mixture fraction and then the degree of fuel/air mixing is calculated by determining the unmixedness. Results show acoustic excitation causes oscillations in the degree of fuel/air mixing at the driving frequency, which results in oscillatory flame behavior. This oscillatory flame behavior couples to the buoyancy and this in turn affects the mixing. Results also show that the mixing becomes less effective when the excitation frequency is increased or when the flame is present, compared to the non-reacting case. This work describes a key coupling mechanism that occurs when buoyancy is a significant factor in the flow field.     

Effects of acetone on electrooxidation of 2-propanol in alkaline medium on the Pd/Ni-foam electrode

Acetone is the main product of 2-propanol electrooxidation in both acid and alkaline electrolytes; it always co-exists with 2-propanol in the reaction solution due to its liquid nature. Whether acetone will affect the electrooxidation of 2-propanol has not been well documented, which is a key issue that needs to be addressed for the direct 2-propanol fuel cell. In this study, the influence of acetone on the electrooxidation of 2-propanol in alkaline medium is investigated, using state-of-the-art Pd electrode, by cyclic voltammetry and chronoamperometry. The electrode is prepared using a chemical replacement method, by dipping nickel foam into acidified PdCl₂ solution, and characterized by scanning electron microscopy. We found that the presence of acetone adversely affects electrooxidation performance of 2-propanol and substantially reduces the oxidation current of 2-propanol on Pd in alkaline medium. The acetone poisoning effect is interpreted by a competitive adsorption mechanism, in which acetone adsorbs onto Pd surface and occupies the active sites for 2-propanol electrooxidation, leading to a significant decrease in the number of these sites for 2-propanol electrooxidation. The results of this study point out that efficient electrocatalysts for 2-propanol electrooxidation in alkaline electrolytes must be non-adsorptive to acetone besides being highly active to 2-propanol oxidation.