A study on the preparation of supported metal oxide catalysts using JRC-reference catalysts. I. Preparation of a molybdena–alumina catalyst. Part 2. Volume of an impregnation solution

Ten types of 13 wt% MoO₃/Al₂O₃ catalysts were prepared by a conventional impregnation or equilibrium adsorption method using a common extrudate support. These catalysts were subjected to a comprehensive characterization and catalytic reactions to find important preparation parameters in practical preparations. It was demonstrated in the present group study that the formation of crystalline MoO₃ was strongly correlated with the Mo segregation on the outer surface of the extrudate. When the amount of the impregnation solution was large (ca. 10 cm³ g-Al₂O₃⁻¹), a considerably homogeneous distribution and high dispersion of Mo oxide species were attained irrespective of the other preparation parameters. It is suggested that when a pore volume impregnation or incipient wetness technique is employed, drying processes strongly affect the dispersion and distribution of Mo oxide species. Drying at a reduced pressure is suggested to result in a segregation of Mo oxides on the outer surface of the extrudate, and accordingly a formation of crystalline MoO₃.     

Changes in evaporation rate and vapor pressure of gasoline with progress of evaporation

The evaporation properties of motor gasoline are expected to change markedly with the progress of evaporation because gasoline is a multi-component fuel. The aim of this paper was to develop a prediction model of the amount of vapor generated from gasoline spill. The risks associated with gasoline spills can be accurately evaluated by the models. Degraded samples of regular gasoline and high-octane gasoline were prepared by leaving them under conditions of no wind at 20 °C, and their vapor pressures and flash points were measured. The evaporation rate was measured by determining weight loss using an electronic balance, and the relation between the weight loss fraction and the evaporation rate was investigated. “Weight loss fraction” was used as a parameter signifying the progress of evaporation and expressed the changes in vapor pressure and evaporation rate as a function of the weight loss fraction. The vapor pressure and the evaporation rate could be shown by exponential functions of the weight loss fraction, and a prediction model of the amount of gasoline vapor was obtained. Furthermore, the prediction model of the flash point of degraded gasoline was derived from the relational expression of temperature and vapor pressure, and the predicted flash points were compared with the measured values.     

Enhanced electrochemical response in oxidative differential pulse voltammetry of dopamine in the presence of ascorbic acid at carboxyl-terminated boron-doped diamond electrodes

The differential pulse voltammetric (DPV) peak for dopamine (DA) oxidation was found to be highly amplified by the addition of ascorbic acid (AA) when carboxyl-terminated boron-doped diamond (BDD) electrodes were used as the working electrode. The DP voltammogram for a solution containing DA and AA obtained using a 4-pentenoic acid-modified BDD (4PA-BDD) electrode showed well-separated oxidation peaks for DA and AA at 0.4 and 0.6 V vs. Ag/AgCl, respectively. In addition, as the DA concentration increased at constant AA concentration, a simultaneous increase in the DA peak current density and decrease in the AA peak current density were observed. The slope of the calibration curve for the [DA] range of 1-10 μM in the presence of AA (500 μM) was seven times larger than that obtained in the absence of AA. Such an enhancement was found to be more efficient at 4PA-BDD than at oxidized-BDD, partly due to simple electrostatic effects and partly due to suppression of the polymerization of DA oxidation products by the terminal carboxyl groups. The enhanced detection method using a carboxyl-terminated BDD electrode should be an effective analytical tool, especially for determining low concentrations of DA in the presence of high concentrations of AA.     

Enantioselective Hydrogenation of (E)-α-phenylcinnamic Acid over Cinchonidine-modified Pd Catalysts Supported on TiO2 and CeO2

The effects of the catalyst support, reaction temperature, and concentration of the modifier were examined to optimize supported Pd-catalysts and reaction conditions for the achievement of higher enantiomeric excess in the hydrogenation of (E)-α-phenylcinnamic acid. Over 90% of enantioselectivity was achieved using a cinchonidine-modified 40 wt% Pd/TiO₂ catalyst at 288 K.     

Structure and mechanical behavior of a toucan beak

The toucan beak, which comprises one third of the length of the bird and yet only about 1/20th of its mass, has outstanding stiffness. The structure of a Toco toucan (Ramphastos toco) beak was found to be a sandwich composite with an exterior of keratin and a fibrous network of closed cells made of calcium-rich proteins. The keratin layer is comprised of superposed hexagonal scales (50 μm diameter and 1 μm thickness) glued together. Its tensile strength is about 50 MPa and Young’s modulus is 1.4 GPa. Micro and nanoindentation hardness measurements corroborate these values. The keratin shell exhibits a strain-rate sensitivity with a transition from slippage of the scales due to release of the organic glue, at a low strain rate (5 × 10⁻⁵/s) to fracture of the scales at a higher strain rate (1.5 × 10⁻³/s). The closed-cell foam is comprised of fibers having a Young’s modulus twice as high as the keratin shells due to their higher calcium content. The compressive response of the foam was modeled by the Gibson–Ashby constitutive equations for open and closed-cell foam. There is a synergistic effect between foam and shell evidenced by experiments and analysis establishing the separate responses of shell, foam, and foam + shell. The stability analysis developed by Karam and Gibson, assuming an idealized circular cross section, was applied to the beak. It shows that the foam stabilizes the deformation of the beak by providing an elastic foundation which increases its Brazier and buckling load under flexure loading.     

Biodiesel Production from Rubber Seed Oil by Transesterification Using a Co‐solvent of Fatty Acid Methyl Esters

Rubber seed oil (RSO) is a high‐potential feedstock for the production of biodiesel fuel (BDF) in Asia. Transesterification using fatty acid methyl esters (FAMEs) as co‐solvents was developed for BDF production from RSO with high content of free fatty acids (FFAs). The homogeneous system (FAMEs/triglyceride/methanol) was attained when the FAME content was more than 30 wt %. After esterification of RSO, the crude RSO obtained was transesterified with FAMEs as a co‐solvent. The quality of BDF with high FAME content satisfied the criteria of the EN 14214/JIS K2390 standards. These results suggest that FAMEs converted from FFAs can be applied as a co‐solvent and, thus, reused for BDF production.     

Biodiesel production by esterification of oleic acid with short-chain alcohols under ultrasonic irradiation condition

Production of fatty acid ethyl ester (FAEE) from oleic acid (FFA) with short-chain alcohols (ethanol, propanol, and butanol) under ultrasonic irradiation was investigated in this work. Batch esterification of oleic acid was carried out to study the effect of: test temperatures of 10–60 °C, molar ratios of alcohol to oleic acid of 1:1–10:1, quantity of catalysts of 0.5–10% (wt of sulfuric acid/wt of oleic acid) and irradiation times of 10 h. The optimum condition for the esterification process was molar ratio of alcohol to oleic acid at 3:1 with 5 wt% of H₂SO₄ at 60 °C with an irradiation time of 2 h.     

Diagnosis of oil-immersed transformers by colorimetry of insulating paper

Power transformers have been expected to work with safety and reliability over a period of more than 30 years. The life expectancy of transformers depends upon the degree of deterioration of insulating materials, particularly conductor insulating paper. Many attempts have been made in recent years to estimate the degree of deterioration of transformers but no diagnostic techniques have been put into practical use because of the difficulty of taking into account the service conditions. It is well known that materials change color when they deteriorate, but no colorimetry study has been made on material deteriorations. According to the recent advances in instrumentation and data processing equipment, the color of materials has become easy to measure qualitatively. Therefore, the basic investigation on colorimetry of insulating papers has been made to clarify the applicability to power transformers. Test results showed a strong correlation between the color difference and the deterioration of insulating paper. This report discusses the effect of materials of papers and impregnating oils on colorimetry.     

Effect of Processed Onions on the Plasma Concentration of Quercetin in Rats and Humans

Onion is a major dietary source of the bioactive flavonoid, quercetin. Quercetin aglycone (QA) is exclusively distributed in the onion peel, although quercetin‐4′‐β‐O‐glucoside (Q4′G) is present in both the peel and the bulb, and quercetin‐3,4′‐β‐O‐diglucoside (Q3,4′diG) is present only the bulb. The bioavailability of flavonoids from fruits and vegetables is frequently affected by the manufacturing process and related conditions. The present study aimed to estimate the effect of food processing on the bioavailability of onion QA and its glucosides, Q4′G and Q3,4′diG, provided through the consumption of onion products. Rats were fed onion peel and onion bulb products‐mixed meal or pure QA/Q4′G+Q3,4′diG‐mixed meal at 5 mg QA equivalent/kg body weight. A comparison of the blood plasma concentrations strongly suggested that quercetin glucosides (Q4′G and Q3,4′diG) are superior or at least equal to QA in their bioavailability, when each purified compound is mixed with the meal. The intake of a peel powder‐containing meal provided a significantly higher increase of plasma quercetin concentration than the peel extract, bulb powder, bulb extract, and bulb sauté containing meals at each period tested. A human ingestion study confirmed the superiority of onion peel powder to onion peel extract. The difference of log P for QA between peel powder and peel extract indicated that a food matrix improves the bioavailability of QA in onion peel products. These results demonstrated that the bioavailability of quercetin provided by not the onion bulb but the onion peel is significantly affected by food processing.