Oxidative coupling of methane over CaO-MgO mixed oxide

Mixed oxide catalyst prepared by co-precipitating magnesium oxide and calcium oxide showed an excellent activity for the oxidative coupling of methane. The high performances were presumed to arise from the high basicity of the mixed oxide.     

Increased hepatic β-oxidation of docosahexaenoic acid, elongation of eicosapentaenoic acid, and acylation of lysophosphatidate in rats fed a docosahexaenoic acid-enriched diet

Rats were fed a diet supplemented with corn oil (n-3 deficient), soy oil, or a mixture containing 8% 22∶6n-3 ethyl ester for 6 wk. The hepatic capacities for the β-oxidation and synthesis of 22∶6n-3, in addition to the acylation of lysophosphatidate, were tested in vitro. In rats that were fed a 22∶6n-3-enriched diet, both the β-oxidation of 22∶6n-3 and elongation of 20∶5n-3 were enhanced compared to those in rats fed the other diets. Acylation of lysophosphatidate was also enhanced in rats fed a 22∶6n-3-enriched diet, while the rate of dephosphorylation of phosphatidate was not changed. The amount of 22∶6n-3 in the liver was much less than that consumed in a docosahexaenoic acid-enriched diet. These results suggest that a significant amount of dietary 22∶6n-3 was degraded via β-oxidation, and that a portion of the retroconverted 20∶5n-3 was recycled for the synthesis of 22∶6n-3. The recycling of 20∶5n-3 might contribute to the low level of 22∶6n-3 in rats fed an n-3-deficient diet.     

Novel fatty acid esters of (7E, 12E, 18R, 20Z)-variabilin from the marine sponge Ircinia felix

The methanolic extract of the marine sponge Ircinia felix has yielded nine novel fatty acid esters, (7E, 12E, 18R, 20Z)-variabilin (5Z, 9Z)-22-methyltricosadienoate, (7E, 12E, 18R, 20Z)-variabilin (5Z, 9Z)-tetracosadienoate, (7E, 12E, 18R, 20Z)-variabilin hexadecanoate, (7E, 12E, 18R, 20Z)-variabilin 10-methylhexadecanoate, (7E, 12E, 18R, 20Z)-variabilin 15-methylhexadecanoate, (7E, 12E, 18R, 20Z)-variabilin 14-methylhexadecanoate, (7E, 12E, 18R, 20Z)-variabilin 9-octadecenoate, (7E, 12E, 18R, 20Z)-variabilin octadecanoate, and (7E, 12E, 18R, 20Z)-variabilin 2,11-dimethyloctadecanoate, along with the recently described (7E, 12E, 18R, 20Z)-variabilin 11-methyloctadecanoate. The characterization of the new fatty acids (5Z, 9Z)-22-methyltricosadienoic and 2,11-dimethyloctadecanoic acids is also described. The chemical structures were determined by extensive spectroscopic, chromatographic, and chemical analyses.     

A highly stable and efficient catalyst for direct synthesis of LPG from syngas

Liquefied petroleum gas (LPG) fuel was directly synthesized from syngas over a hybrid catalyst which contained a methanol synthesis catalyst and zeolite. The new hybrid catalyst composed of (Pd–Ca/SiO₂) and β-zeolite, showed a high activity and selectivity for LPG production. X-ray diffraction (XRD) characterization of the catalyst was used to analyze the deactivation of (Pd–Ca/SiO₂)/β-zeolite.     

The study of polymers by high-temperature ATR spectroscopy

A new high-temperature attenuated total reflectance apparatus (HATR) was constructed and used at different temperatures for making infrared measurements on the same liquid or solid sample. It was found that this method was applicable to the continuous quantitative analysis of changes occurring during chemical reactions such as polymerization, isomerization, and crosslinking. In the bulk polymerization of styrene, the process of monomer consumption could be followed progressively. In the crosslinking reaction of high cis-polybutadiene by sulfur-accelerator or peroxide crosslinking systems, the decrease of cis content and its partial isomerization to trans structure was measured. Furthermore, in the crosslinking reaction of ethylene–propylene terpolymers (EPDM), the consumption of double bonds was observed over the course of the reaction with both sulfur-accelerator and peroxide crosslinking systems. The effect was greatest in the case of methylenenorbornene-type EPDM.     

Oxidation of synthetic triacylglycerols containing eicosapentaenoic and docosahexaenoic acids: Effect of oxidation system and triacylglycerol structure

Thirteen synthetic triacylglycerols (TAG) containing eicosapentaenoic acid (EPA) or docosahexaenoic acid (DHA) were oxidized in the presence of 2,2′-azobis(2,4-dimethyl-valeronitrile) (AMVN) and 2,2′-azobis(2-amidinopropane)dihydrochloride (AAPH) as aqueous and nonaqueous radical initiators to investigate the influence of TAG structure and oxidation system on the oxidative stability of TAG that contain highly unsaturated fatty acids (HUFA). A 2:1 (mol/mol) mixture of trieicosapentaenoylglycerol and tripalmitoylglycerol was most susceptible to the AMVN-initiated oxidation among three types of TAG that contained EPA and palmitic acid (2:1, mol/mol). Compared with 1,2 (or 2,3)-dieicosapentaenoyl-3(or 1)-palmitoylglycerol (EEP) and 1,3-dieicosapentaenoyl-2-palmitoylglycerol (EPE), the oxidative rate of EEP was somewhat higher. A similar result was obtained for DHA-containing TAG. The oxidative rate of TAG that contained EPA and palmitic acid (1:2, mol/mol) showed a positive correlation with the amount of EPA in a single TAG molecule. Moreover, in the nonaqueous system, the oxidative rate of EPA-containing TAG was affected by unsaturation and carbon chainlength of constituent fatty acids. In the AAPH-initiated oxidation in the aqueous system, the oxidative rate of TAG with EPA and palmitic acid was higher with the increased quantity of EPA in a single TAG molecule. Also, constituent fatty acids modified the oxidative rate of EPA-containing TAG in an aqueous system. The glycerol position of EPA and DHA also affected the oxidative rate of the TAG. EPA and DHA located at the 1,2 (or 2,3)-position of glycerol were more oxidizable than those at the 1,3-position during AAPH-initiated oxidation. Thus, 1,2(or2,3)-dipalmitoyl-3(or 1)-eicosapentaenoylglycerol was oxidized faster than 1,3-dipalmitoyl-2-eicosapentaenoylglycerol. These observations suggest that the oxidative stability of TAG that contain HUFA could be modulated by the oxidation system and TAG structure.     

Evaluation of the wettability of spherical cement particle surfaces using penetration rate method

The wettability of cement particles is related to the fluidity of cement paste. This paper describes the mechanism of the higher fluidity imparted by the spherical cement particles in light of their wettability. In addition, the effects of gypsum on the wettability were also studied. This study has shown the following: (1) The weight of water and water-reducing agent solution penetrating the spherical cement powder bed is 24-150% higher than that for the ordinary Portland cement powder bed. This results in the improvement of the wettability of the particle surfaces of spherical cement. The high wettability of spherical cement contributes to its high fluidity. (2) The presence of many fine gypsum particles on the spherical cement particle surface reduces the wettability. (3) To prepare spherical cement, the optimum amount of gypsum added is determined by the acceleration of the formation of spherical particles and the wettability of particle surfaces.     

Glass transition behavior of emulsion-polymerized polymer films containing a surface-active agent

The glass transition behavior of emulsion-polymerized poly(methyl methacrylate) and polystyrene films containing sodium laurylsulfate as emulsifier was studied by measurements of dynamic mechanical properties and thermal depolarization current. The film specimens of the emulsion-polymerized polymers were prepared by casting from their benzene solutions. The glass transition temperatures of the emulsion-polymerized films are higher than those of the bulk-polymerized films. The higher glass transition temperature of the emulsion-polymerized films is attributed to the colloidal properties of sodium laurylsulfate in the process of the film formation. The restriction of the molecular chains in the emulsion-polymerized films is attributed to the interaction between the hydrophobic groups of sodium laurylsulfate and the polymer molecules.     

Growth of β-Alumina (Na2O · 11Al2O3) Single Crystals by the Flux Method

The crystal-growth process and growth conditions of β-alumina (Na₂O · Al₂O₃) were investigated using the Na₂B₄O₇-Na₃AlF₆ flux method. β-Alumina (electric fusion brick) was used as both nutrient and seed. Weight loss of the flux varied widely for various runs: ≅ 10 wt% of flux evaporated at 100 h, ≅ 17 wt% at 150 h, and 43 wt% at 600 h. When β-alumina crystal was grown, only 20 wt% Na₂B₄O₇ was added to the Na₃AlF₆ flux. The linear growth rates of the β-alumina single crystal grown by an Na₃AlF₆-20 wt% Na₂B₄O₇ flux method at 1040°C and Δ t = 18°C were ≅ 1.0 × 10⁻³ mm/h ( a face) and ≅0.3 × 10⁻³ mm/h ( c face). The β-alumina single crystals grown were bounded by only c [001] and a [100] and were colorless and transparent.     

Deterioration of diacylglycerol‐ and triacylglycerol‐rich oils during frying of potatoes

The stabilities of a commercial diacylglycerol‐rich oil (DAG) and a salad oil (TAG) that had been prepared from a mixture of rapeseed and soybean oils were compared while frying potatoes at 180 °C for 3 h. The representative chemical and physical characteristics of the oils were assessed before and after frying, together with the amount of volatile aldehydes in the exhaust of frying. Among the deterioration indications, the carbonyl value, polymer content, and residual polyunsaturated fatty acid content were similar and not significantly different between the TAG and DAG. On the other hand, the characteristics relating to free fatty acids, i.e. the acid value and emission of chemiluminescence at 100 °C, were greater and the smoke and flash points were lower in the DAG than in the TAG. An irritating odor was generated from the DAG after 1 h of frying and got stronger as frying continued. These results suggested that DAG more easily forms free fatty acids under frying conditions than TAG.