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31.
Lisbeth M Ottosen Ana T Lima Anne J Pedersen Alexandra B Ribeiro 《Journal of chemical technology and biotechnology (Oxford, Oxfordshire : 1986)》2006,81(4):553-559
The possibility of using fly ash from municipal solid waste incineration (MSWI) in, for example, concrete is considered. MSWI fly ash, however, has too high a concentration of heavy metals, which may cause leaching problems during use or problems with waste handling at the end of the lifetime of the concrete. The Cl content in MSWI fly ash is also too high and will cause corrosion problems in reinforced concrete. The possibility of removing some of the unwanted heavy metals (Cu and Pb) together with Cl from an MSWI fly ash suspended in water using an electrodialytic separation method was investigated. The removal of Pb and Cu was found to be highly pH dependent and the highest contents removed were 41 and 90%, respectively. The Cu concentration of the ash decreased from 2200 to 860 mg kg?1 but the Pb concentration increased from 8560 to 16 800 mg kg?1, showing that Pb is mainly found in the ash fraction that is least soluble. Hence electrodialytic treatment of the ash suspended in water is not a solution to improve the ash quality in terms of Pb. The water‐soluble Cl content per unit weight of the original ash was 12.4%. The removal of water‐soluble Cl was efficient and >98% of Cl was removed (calculated on the basis of mean initial and final concentrations). This result indicates that electrodialytic extraction may be a method that can be used for the removal of Cl from ash prior to its utilization in concrete. Copyright © 2006 Society of Chemical Industry 相似文献
32.
Dehydrogenation of Light Alkanes Over Rhenium Catalysts on Conventional and Mesoporous MFI Supports 总被引:1,自引:0,他引:1
Anne Krogh Rovik Anke Hagen Iver Schmidt Søren Dahl Ib Chorkendorff Claus Hviid Christensen 《Catalysis Letters》2006,109(3-4):153-156
Recently, Re/HZSM-5 (Si/Al = 15) was shown to be an efficient catalyst for ethane dehydrogenation and aromatization at 823 K
and atmospheric pressure. In this reaction, the major initial products were benzene, toluene and xylene (BTX), but increasing
amounts of ethene were produced with time on stream due to deactivation of the catalyst. We show that by use of rhenium impregnated
MFI supports with very few or no acidic sites (Si/Al > 500), highly selective ethane dehydrogenation catalysts are obtained
with ethene selectivities of 98%. By use of mesoporous MFI supports (Si/Al >500) the lifetime of the catalyst appears to be
slightly improved compared to conventional MFI crystals. The beneficial effect of a mesoporous MFI support is convincingly
demonstrated in propane dehydrogenation, where both conversion and selectivities on the mesoporous MFI (Si/Al > 500) impregnated
with Re are significantly higher than on Re supported on a comparable conventional MFI support. 相似文献
33.
Said Ghaout Alain Louveaux Anne Marie Mainguet Max Deschamps Youssef Rahal 《Journal of chemical ecology》1991,17(8):1499-1515
A field study of the food eaten by solitary desert locusts was carried out in a winter breeding area in Mauritania. The food eaten, determined by the plant epidermis found in fecal pellets, was compared to the plant's availability in the habitat.Schouwia purpurea, well represented in the diets, was dominant at the study site. Adults had a preference forTribulus terrester. Growth and feeding on these two plants were compared. The high water content ofS. purpurea leaves limited the dry matter eaten and slowed down growth. Glucosinolates were separated and quantified by gas chromatography. There are 132mol/g dry matter in green leaves. In multiple choice tests, with paper disks, glucosinolate extracts were phagostimulant at a low concentration (21mol/g dry matter) and repulsive at a higher one (214mol/ g dry matter). Biting behavior onS. purpurea was recorded and analyzed on video. The importance ofSchouwia purpurea in desert locust habitats and its defenses is discussed. 相似文献
34.
Antioxidant activity of grape extracts in a lecithin liposome system 总被引:15,自引:0,他引:15
Ock-Sook Yi Anne S. Meyer Edwin N. Frankel 《Journal of the American Oil Chemists' Society》1997,74(10):1301-1307
Extracts of 14 different grapes were tested for their antioxidant activities in a copper-catalyzed lecithin liposome oxidation
assay and analyzed for their phenolic components by high-performance liquid chromatography (HPLC). The total phenolic contents
of the grape extracts varied from 176 to 1236 mg gallic acid equivalents (GAE)/L. Extracts of red wine grape varieties contained
higher concentrations of phenolics than other varieties. When compared at the same 20 μM GAE basis, the grape extracts inhibited
formation of conjugated diene hydroperoxides by 25.1 to 67.9%, and hexanal formation by 49.3 to 97.8%. Extracts of red table
grape varieties Red Globe and Emperor and white wine grape varieties Chardonnay and Sauvignon Blanc gave the highest antioxidant
activities. The relative percentage inhibition of conjugated dienes and hexanal correlated with total phenols (r=0.86 and 0.89). HPLC analyses showed that anthocyanins were the most abundant phenolic compounds in extracts of red grapes,
and flavonols were most abundant in extracts of white grapes. 相似文献
35.
Tiina Reponen Anne Hyv rinen Juhani Ruuskanen Taisto Raunemaa Aino Nevalainen 《Journal of aerosol science》1994,25(8):1595-1603
Concentrations and types of airborne fungal spores and their aerodynamic sizes were studied in nine buildings with mould problems and in matched reference buildings in order to characterize the exposure in buildings with mould problems. Samples were taken with Andersen six-stage impactors in the autumn and winter. In winter, total concentrations of fungal spores in buildings with mould problems were twice those in reference buildings, even though all concentrations were quite small. In the autumn, the differences were less obvious due to the masking effect of outdoor air fungi. Also, the compositions of fungal genera differed in buildings with mould problems from that in reference buildings. The difference was most significant in the size range 2.1-4.7 μm. The size distribution of fungal spores in dwellings with mould problems skewed towards larger particles than in reference dwellings. The observed differences in size distribution indicate differences in airborne behaviour of fungal spores and, consequently, in respiratory exposure. 相似文献
36.
Kinetics of alkaline hydrolysis of mica-acrylonitrile graft copolymers was studied. The dependence of alkali concentration and the time of hydrolysis on the degree of saponification was determined. Chemical and spectroscopical techniques were used to determine the mechanism of hydrolysis. 相似文献
37.
Louise M. Canfield Judy M. Hopkinson Anne F. Lima Gail S. Martin Kyoto Sugimoto Jeanne Burr Larry Clark Daniel L. McGee 《Lipids》1990,25(7):406-411
A quantitative method was developed for the assay of vitamin K in human colostrum and milk. The procedure combines preparative
and analytical chromatography on silica gel in a nitrogen atmosphere followed by reversed phase high performance liquid chromatography
(HPLC). Two HPLC steps were used: gradient separation with ultraviolet (UV) detection followed by isocratic separation detected
electrochemically. Due to co-migrating impurities, UV detection alone is insufficient for identification of vitamin K. Exogenous
vitamin K was shown to equilibrate with endogenous vitamin K in the samples. A statistical method was incorporated to control
for experimental variability. Vitamin K1 was analyzed in 16 pooled milk samples from 7 donors and in individual samples from 15 donors at 1 month post-partrum. Vitamin
K1 was present at 2.94±1.94 and 3.15±2.87 ng/mL in pools and in individuals, respectively. Menaquinones, the bacterial form
of the vitamin, were not detected. The significance of experimental variation to studies of vitamin K in individuals is discussed. 相似文献
38.
Anne Bagley Hardy Wendell E. Rhine H. Kent Bowen 《Journal of the American Ceramic Society》1993,76(1):97-104
A new method for forming spherical, submicrometer ceramic oxide particles by the hydrolysis of emulsified alkoxide droplets is reported. Emulsions are formed of alkoxide droplets dispersed in an inert, polar solvent. The alkoxide droplets are hydrolyzed to form oxide particles by adding water to the emulsion. It was shown that individual droplets acted as "microreactors" and controlled the powder size, shape, and composition. Both single-oxide and mixed-oxide powders were formed by this technique. 相似文献
39.
We are investigating the bulk and interfacial chemistry of polyimide (PI) exposed to heat and relative humidity (RH) stress (85°C/85% RH) over long periods to understand the long-term reliability aspects of PI for microelectronic applications. The PI surface chemistry and the PI–Si interface chemistry was followed with electron spectroscopy for chemical analysis (ESCA). For exposure times greater than 550 h, the PI surface exhibits significant changes in emission structure and atomic concentration. The PI–Si interface indicates little change in the PI chemistry when compared to control samples. The water-contact angle at the PI surface shows no statistically significant change as a function of exposure time. Bulk and surface chemistry were followed with Fourier transform infrared spectroscopy (FTIR) in a grazing incidence reflection configuration. There were measurable differences in FTIR spectra between aged and control samples only for the case of very thin PI layers. These results suggest that for exposure times of less than 1100 h, chemical changes in PI occur primarily at the PI–air interface for samples 1 μm thick and greater. These changes represent a possible rearrangement of the imide structure and may be a form of deimidization of the polymer, but the final state is not polyamic acid. The PI surface chemistry changes observed with ESCA are reversible upon reheating to the cure temperature. 相似文献
40.
Associations between apolipoprotein E genotype and circulating F<Subscript>2</Subscript>-isoprostane levels in humans 总被引:1,自引:0,他引:1
Dietrich M Hu Y Block G Olano E Packer L Morrow JD Hudes M Abdukeyum G Rimbach G Minihane AM 《Lipids》2005,40(4):329-334
Apolipoprotein E (apoE), an important determinant of plasma lipoprotein metabolism, has three common alleles (ε2, ε3, and
ε4). Population studies have shown that the risk of diseases characterized by oxidative damage, such as coronary heart disease
and Alzheimer’s disease, is significantly higher in ɛ4 carriers. We evaluated the association between apoE genotypes and plasma
F2-isoprostane levels, an index of lipid peroxidation, in humans. Two hundred seventy-four healthy subjects (104 males, 170
females; 46.9±13.0 yr; 200 whites, 74 blacks; 81 nonsmokers, 64 passive smokers, and 129 active smokers) recruited for a randomized
clinical antioxidant intervention trial were included in this analysis. ApoE genotype was determined by PCR and restriction
enzyme digestion. Free plasma F2-isoprostane was measured by GC-MS. Genotype groups were compared using multiple regression analysis with adjustment for sex,
age, race, smoking status, body mass index, plasma ascorbic acid, and β-carotene. Subjects with ε3/ε4 and ε4/ε4 genotype (ε4-carriers)
and with ε2/ε3 and ε3/ε3 (non-ε4-carriers) were pooled for analysis. In subjects with high cholesterol levels (total cholesterol
above 200 mg/dl), plasma F2-isoprostane levels were 29% higher in ε4 carriers than in non-ε4-carriers (P=0.0056). High-cholesterol subjects that are ε4 carriers have significantly higher levels of lipid peroxidation as assessed
by circulating F2-isoprostane levels. 相似文献