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391.
Summary Amine-modified and alkylated (with butyl bromide or hexyl bromide) acrylonitrile-butyl acrylate-divinylbenzene terpolymers and alkyl acrylate-divinylbenzene copolymers (where alkyl=methyl, ethyl or butyl) were used as catalysts in the reaction of octyl bromide with cyanide anions. The dependence of catalytic activity as a function of the acrylate content and swelling properties was investigated. The most effective catalyst was butyl acrylate-divinylbenzene copolymer. This sample showed maximum toluene uptake from the toluene/water mixture. 相似文献
392.
Modelling of flocculation and transport of cohesive sediment from an on-stream stormwater detention pond 总被引:2,自引:0,他引:2
A new model to predict the transport characteristics of suspended sediment from an on-stream stormwater management pond is presented. It is based on Krishnappan's model of flocculated settling in still water, which was extended to dynamic conditions and verified by experiments with stormwater pond sediment in a laboratory rotating flume. The model was derived from first principles, but some input parameters, such as floc properties, had to be obtained by calibration, and input parameters describing flow field properties were obtained from a kappa-epsilon turbulence model. Simulated suspended concentrations vs. time and the size distribution of the flocculated sediment, produced with the calibrated model, agreed well with flume measurements. 相似文献
393.
In this work, we present a novel surface and assay for the simultaneous detection of DNA and protein analytes on a surface plasmon resonance (SPR) imaging sensor. A mixed DNA/oligo (ethylene glycol) (OEG) self-assembled monolayer (SAM) is created using a microarrayer. Thiol-modified single-stranded DNA sequences are spotted onto a gold-coated glass substrate. Backfilling with an OEG-modified alkanethiol creates a protein-resistant surface background. Antibodies conjugated to complementary single-stranded DNA sequences are immobilized on the surface through DNA hybridization. By converting only part of the DNA array into a protein array, simultaneous detections of DNA and protein analytes are possible. A model system of two cDNA sequences and two human pregnancy hormones are used to demonstrate the assay. No cross-reactivity was observed between DNA or protein analytes and nontargeted immobilized cDNA sequence or antibodies. A response from a detection of a single analyte in a mixture of protein and DNA analytes corresponds well with that of a single-analyte solution. 相似文献
394.
ABSTRACT The paper presents results of water sorption tests of dried blood flour carried out tinder laboratory conditions and mathematical analyses of sorption isotherms obtained. Moisture equilibrium data were investigated at air temperatures in the range of 20–50°C and water activity ranging from 0 4 to 0 99. The experimental procedure used was a gravimetric dynamic method with continuous registration of sample weight changes. Sorption capacity decreases as temperature increases. Rehydration of the dried material results in hysteresis but this phenomenon was small. Four models of equilibrium moisture content/equilibrium relative air humidity (Chung—Pfost. Halsey. Henderson, and Oswin) were evaluated for their ability to fit data for the samples of dried blood. The modified Henderson equation was a good model for moisture adsorption and desorption of dried blood flour 相似文献
395.
Petr Zaloha Jiri Kristal Vladimir Jiricny Norbert Völkel Catherine Xuereb Joelle Aubin 《Chemical engineering science》2012,68(1):640-649
The hydrodynamics of liquid slugs in gas–liquid Taylor flow in straight and meandering microchannels have been studied using micro Particle Image Velocimetry. The results confirm a recirculation motion in the liquid slug, which is symmetrical about the center line of the channel for the straight geometry and more complex and three-dimensional in the meandering channel. An attempt has also been made to quantify and characterize this recirculation motion in these short liquid slugs (Ls/w<1.5) by evaluating the recirculation rate, velocity and time. The recirculation velocity was found to increase linearly with the two-phase superficial velocity UTP. The product of the liquid slug residence time and the recirculation rate is independent of UTP under the studied flow conditions. These results suggest that the amount of heat or mass transferred between a given liquid slug and its surroundings is independent of the total flow rate and determined principally by the characteristics of the liquid slug. 相似文献
396.
397.
MgH2 is a perspective hydrogen storage material whose main advantage is a relatively high hydrogen storage capacity (theoretically, 7.6 wt.% H2). This compound, however, shows poor hydrogen desorption kinetics. Much effort was devoted in the past to finding possible ways of enhancing hydrogen desorption rate from MgH2, which would bring this material closer to technical applications. One possible way is catalysis of hydrogen desorption. This paper investigates separate catalytic effects of Ni, Mg2Ni and Mg2NiH4 on the hydrogen desorption characteristics of MgH2. It was observed that the catalytic efficiency of Mg2NiH4 was considerably higher than that of pure Ni and non-hydrated intermetallic Mg2Ni. The Mg2NiH4 phase has two low-temperature modifications below 508 K: un-twinned phase LT1 and micro-twinned phase LT2. LT1 was observed to have significantly higher catalytic efficiency than LT2. 相似文献
398.
399.
A simplified theory is developed that yields the approximate stresses within a dust cake on the outer surface of ceramic candle filter and gives the critical factors which ensure complete detachment of cake. The radial and tangential stresses in cake during filtration have been derived by consideration of active state of stress in the dust cake. Back pulses of cleaning gas expand dust cake on the condition, that their power is just adequate to properties of cake, such as angle of internal friction and cohesion. Expansion of the dust cake induces tension cracks and disintegration of the cake. Back pulses of higher values hamper expansion of cake and cause “patchy” cleaning. 相似文献
400.
Laura Bocher Myriam H. Aguirre Rosa Robert Dmitry Logvinovich Snejana Bakardjieva Jiri Hejtmanek Anke Weidenkaff 《Acta Materialia》2009,57(19):5667-5680
Polycrystalline perovskite-type CaMn1-xNbxO3 phases (with x=0.02,0.05,0.08 and 0.10) were investigated with regard to their structure, microstructure and thermal stability as a function of temperature. The studied phases revealed a complex microstructure at room temperature with 90° twinned domains. At high temperatures, the manganate phases underwent a structural transition from orthorhombic to cubic symmetry, as confirmed by in situ high-temperature X-ray powder diffraction and electron diffraction data. Thermogravimetric heating/cooling studies showed a reversible thermal reduction/reoxidation process that occurred above a defined transition temperature. A possible mechanism relating the high-temperature structural transition and the thermal reduction process of slightly substituted CaMnO3 phases was proposed. The thermal reduction process resulted in a change in the Mn3+/Mn4+ concentrations in the Mn sublattice, and therefore in a modification of the transport properties. A comprehensive study examined the impact of both phenomena on the electrical and thermal transport properties. 相似文献