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91.
Microwave irradiation processing (MIP) was considered as a potential method to synthesize perovskite-type oxides rapidly, cleanly and energy-efficiently. In this paper, La0.7Sr0.3MnO3+λ, a kind of promising catalyst for automobile exhaust purification, was successfully prepared by MIP in not more than 5 min. The sol–gel method was also used for comparison. All the samples were evaluated by catalytic activity tests in the simulated exhaust and characterized by XRD, BET, TEM and XRF analyses. The results showed that the integrated perovskite-type phase and uniform particle size were obtained in the microwave-treated samples. And those ones exhibited a better oxidation activity under slightly oxygen-rich condition than that by sol–gel method, which may be related to more A-site cation vacancies and larger bulk oxygen content generated in MIP. Possible formation mechanism of perovskites in MIP was also discussed. 相似文献
92.
Latexes with intrinsic crosslink activity 总被引:1,自引:0,他引:1
In order to develop and study ‘two pack in one pot’ systems, i.e. binder systems consisting of a blend of complementary reactive latexes, epoxy- and amino-functional latexes were prepared and characterised, with atte lion especially directed to control of the number of functional groups and control of the molecular weight. The investigation is focused on the control of the molecular weight of epoxy-functional latexes and on the incorporation of amino groups in latexes by using amino-functional methacrylic monomers. To determine the reactivity of the epoxy and amino groups and to check which factors influence the crosslink reaction a number of blends were prepared from both solution and emulsion copolymers and dried at ambient temperatures. It was found that the major factors, which affect the efficiency of crosslinking, are the Tg and the molecular weight of the copolymers and, in the case of a ‘two pack in one pot system’, the rate of the polymer-polymer reaction in relation to that of the polymer-polymer interdiffusion. 相似文献
93.
Yong-Seo Park Seong-Gook Kang Alma Leticia Martinez Ayala Olga Martín-Belloso Shela Gorinstein 《LWT》2006,39(7):748-755
Fresh persimmons were subjected to two different processes: sun-drying during 1 month and dehydration at 60 °C during 12 h. To assess the effect of this process on nutritional and health-related properties of persimmons dietary fibers, minerals, trace elements, polyphenols and the total radical scavenging activities (TRSAs) were determined before and after processing. It was found that the contents of dietary fibers, minerals and trace elements in fresh and dried persimmons fruits were comparable. Total polyphenols in fresh persimmons was higher than in dried fruits (1.3 vs. 0.9 and 0.8 mg/100 g FW, respectively) and percentage of inhibition was higher than in dried fruits (70% vs. 59% and 55% and 58% vs. 53% and 46% for 1,1-diphenyl-2-picrylhydrazyl (DPPH) and 2,2′-azino-bis (3-ethylbenzthiazoline-6-sulfonic acid) [ABTS] radicals, respectively (P>0.05 in all cases). In conclusion: (1) the differences in the contents of dietary fibers, minerals and trace elements in fresh and dried persimmons are not significant; (2) the contents of polyphenols and the level of the TRSA are higher in fresh persimmons than in dried fruits; however, both variables are also high in dried persimmons; (3) when fresh fruits are not available, proper dried persimmons could be used as a valuable substitute. 相似文献
94.
95.
Maciej Winiewski Artur Jakubiak Jan Szymanowski 《Journal of chemical technology and biotechnology (Oxford, Oxfordshire : 1986)》1995,63(3):209-214
Decyl isonicotiniate and decyl nicotiniate permit a rapid extraction of palladium(II) from its hydrochloride solutions. Decyl picoliniate is not a suitable extractant. 4-Octylphenylamine can act as a phase transfer catalyst when its concentration in the organic phase is at least 2·5 × 10?4 M . It seems that the interfacial adsorption of pyridine carboxylates and of 4-octylphenylamine is not the decisive phenomenon in palladium(II) extraction. The negligible protonation of the pyridine-type extractants and the phase transfer catalysis explains well the quick extraction of palladium(II) with the commercial and highly hydrophobic extractant ACORGA CLX-50. 相似文献
96.
Since proteose-peptone is a mixture of heterogeneous proteins and peptides, its functional properties have not yet been fully understood. The present study was undertaken to elucidate the emulsifying properties of proteose-peptones and a parallel evaluation was performed of the emulsifying activity of the total fraction prepared from bulk skimmed milk by precipitation with ammonium sulphate and of the most hydrophobic fraction purified by hydrophobic interaction fast protein liquid chromatography. A turbidimetric technique was used and the absorbance value at 500 nm was then directly used as the emulsifying activity index. The results obtained confirmed the good emulsifying activity of this protein fraction of the whey and demonstrated the considerable influence of the concentration on the capacity of the proteose-peptones to stabilize a model oil-in-water emulsion. Moreover, at all the concentrations examined, the purified component 3 showed a higher emulsifying activity than the total unpurified fraction. 相似文献
97.
Modified Atmosphere Packaging Affects Ascorbic Acid, Enzyme Activity and Market Quality of Broccoli 总被引:1,自引:0,他引:1
Reduced ascorbic acid (RAA) content, total chlorophyll and green color retention, enzyme activities and texture changes were followed in broccoli spears packaged in polymeric film and nonpackaged during 96 hr storage (10°C). Concentrations within packages monitored by gas chromatography were (CO2,) 8% and (02) 10%. RAA retention, moisture content, total chlorophyll and color retention were greater in packaged broccoli. No differences were found between packaged and nonpackaged broccoli for ascorbate oxidase and peroxidase activities, or texture. 相似文献
98.
Peng Dangcong Jin Qiting 《Journal of chemical technology and biotechnology (Oxford, Oxfordshire : 1986)》1993,58(1):89-93
The anaerobic digestion of alkaline black liquor from a cereal straw pulping mill was studied in batch (serum bottles) and continuous systems (up-flow anaerobic sludge blanket reactor—UASB). The batch digestion studies confirmed that lignin and related compounds (LRC) in the alkaline black liquor were the main inhibitory substances and could not be decomposed by anaerobic bacteria. At organic loading rates of 5–10 kg COD m?3 day?1, the UASB reactor achieved 50–60% COD removal efficiencies. Gas production was 2–3 dm3 per dm3 of alkaline black liquor. Two different sludge types were examined in the reactor: granular and cluster-like sludges. Sludge in a cluster, which involved many small granules and flocs, tended to form larger aggregates and possessed good settling ability. 相似文献
99.
在钼丝炉内氩气保护下,利用固体电解质定氧探头测定了含镓1.87%~6.21%范围内Fe-Ga-O三元系平衡时的氧活度,通过处理得到镓在铁液中的标准溶解自由能等热力学参数与温度的关系。 相似文献
100.
《Journal of Great Lakes research》2021,47(6):1581-1593
On Great Lakes dunes, the link between foredune dynamics and coastal processes is seen in dune responses to changing lake levels. This paper investigates foredune dynamics during a recent period of rising and high lake levels. The study location was an active foredune in P.J. Hoffmaster State Park on the east coast of Lake Michigan, where field data were collected from 2000 through the final destruction of the foredune by wave removal in November 2019. Foredune dynamics were studied with erosion pins, direct observations, photographs, mapping, and on-site wind measurements. Regional climate and lake-level data were obtained from established data collection programs. The response of the foredune to rising lake levels was compared to several models of foredune behavior. During the study, the Lake Michigan-Huron level rose 1.89 m from January 2013 to July 2020. After an early transitional period, foredune activity was characterized by scarp retreat (4–19 m per year) and dune narrowing from 2014 to 2019. When the foredune completely disappeared in November 2019, erosion/scarping began on the next landward dune. The foredune activity fits Olson’s (1958) model for foredune growth and erosion through lake-level cycles. The foredune migration predicted by the revised Davidson-Arnott (2021) model of foredune response to relative water level rise did not occur, most likely because the rate of lake-level rise was too high. The six years of foredune narrowing before wave erosion started affecting the next landward dune represent a time-lag in Lake Michigan dune history models of increased dune activity during high lake-level stands. 相似文献