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91.
The applications of membrane separation within the bioconversion of lignocellulosic materials to ethanol are studied, and this paper reports on cellulolytic enzyme recovery, and reduction of the product inhibition. The conversion of cellulose and hemicellulose to hexoses and pentoses is carried out in a laboratory scale UF-membrane reactor, and the sugars, which have an inhibiting effect on the enzymes, are continuously removed with the permeate. By optimizing the space velocity, the enzyme inhibition is minimized and the rate of hydrolysis is significantly increased.The recovery of the enzymes has also been investigated with regard to their mechanical stability and adsorption on the substrate. Prior to enzymatic hydrolysis, the raw material is subjected to a pretreatment to make the cellulose more accessible to the enzymes, and the effect of the pretreatment can easily be evaluated in the UF-membrane reactor.As a result of the continuous removal of products formed in the hydrolysis, the permeate has a low content of fermentable sugars, and to give the optimal conditions for the fermentation a concentration step is needed. Different RO-membranes are tested in a laboratory scale batch cell to be able to choose a membrane material, fit for filtration in larger modules. 相似文献
92.
Kolli T. Rahkamaa-Tolonen K. Lassi U. Savimäki A. Keiski R. L. 《Topics in Catalysis》2004,30(1-4):341-346
Topics in Catalysis - The interaction of CO, C2H4, O2, and NO reaction gas compounds over the metallic Pd/Al2O3 and Pd/OSC/Al2O3 monoliths was investigated in order to understand the behaviour of... 相似文献
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94.
Pontus Johnson Maria Eugenia Iacob Margus Välja Marten van Sinderen Christer Magnusson Tobias Ladhe 《Information Systems and E-Business Management》2014,12(4):567-593
In the design phase of business collaboration, it is desirable to be able to predict the profitability of the business-to-be. Therefore, techniques to assess qualities such as costs, revenues, risks, and profitability have been previously proposed. However, they do not allow the modeler to properly manage uncertainty with respect to the design of the considered business collaboration. In many real collaboration projects today, uncertainty regarding the business’ present or future characteristics is so significant that ignoring it becomes problematic. In this paper, we propose an approach based on the predictive, probabilistic architecture modeling framework (P2AMF), capable of advanced and probabilistically sound reasoning about profitability risks. The P2AMF-based approach for profitability risk prediction is also based on the e3-value modeling language and on the object constraint language. The paper introduces the prediction and modeling approach, and a supporting software tool. The use of the approach is illustrated by means of a case study originated from the Stockholm Royal Seaport smart city project. 相似文献
95.
Positional isomers (1-butyryl-2X-3Y-rac-glycerol and 2-butyryl-1X-3Y-rac-glycerol;X,Y=long-chain acyls) of saturated triacylglycerols (TAG) with 34 and 40 acyl carbons were shown to separate in two chromatographic
peaks on immobilized phenyl(65%) methylsilicone column by gas-liquid chromatography, and on reversed-phase ODS-1 column by
high-performance liquid chromatography. The analysis of 500-MHz1H nuclear magnetic resonance (NMR) spectra showed distinct differences between 2-butyryl-1X-3Y-rac-glycerol and 1-butyryl-2X-3Y-rac-glycerol isomers in the resonance signals of methylene and methine protons of glycerol backbone, and carbon-2 methylene of
acyl groups, and methyl protons of butyryl group. The1H NMR spectra of three interesterified mixtures of three monoacid TAG containing saturated butyrate and caproate TAG and unsaturated
butyrate TAG showed that triplets of methyl protons of butyryl groups atsn-1(3)- andsn-2-positions in saturated and unsaturated TAG had similar chemical shifts and that the chemical shift of caproyl methyl protons
was different from those of butyryl methyl protons. The positional distribution of butyryl groups in isolated positional isomers
of butyrate TAG, interesterified TAG mixtures, and natural and interesterified butteroil can be determined by integration
of these signals. 相似文献
96.
A theoretical approach to the kinetics of the thermal decomposition of molten thermoplastic polyurethane elastomers, under conditions of thermoplastic processing, is described. On the basis of these considerations, the thermal decomposition in different instruments (melt index analyser and measuring extruder) can be described quantitatively and the various results can be compared. As a result, identical conditions of decomposition of the melt can be defined accurately, thus opening up the possibility of combining experimental values from different instruments. The fundamental kinetic equation obtained for the kinetics of the thermal decomposition of thermoplastic polyurethanes describes the decomposition reaction and the reverse reaction (formation reaction) – which is dependent on the system of measurement and processing – as a function of the molar mass (end‐group concentration) of the original product, determined from the velocity constants for the decomposition reaction and back reaction. The consideration of the limiting value for t → ∞ is in agreement with the equilibrium constant. Consequently, the development of physical characteristic functions of thermoplastic polyurethane elastomers – independent of the system of measurement – is possible.
97.
98.
99.
Ribosome display of mammalian receptor domains 总被引:2,自引:0,他引:2
Many mammalian receptor domains, among them a large number of potential therapeutic target proteins, are highly aggregation-prone upon heterologous expression in bacteria. This severely limits functional studies of such receptor domains and also their engineering towards improved properties. One of these proteins is the Nogoreceptor, which plays a central role in mediating the inhibition of axon growth and functional recovery after injury of the adult mammalian central nervous system. We show here that the ligand binding domain of the Nogoreceptor folds to an active conformation in ternary ribosomal complexes, as formed in ribosome display. In these complexes the receptor is still connected, via a C-terminal tether, to the peptidyl tRNA in the ribosome and the mRNA also stays connected. The ribosome prevents aggregation of the protein, which aggregates as soon as the release from the ribosome is triggered. In contrast, no active receptor was observed in phage display, where aggregation appears to prevent incorporation of the protein into the phage coat. This strategy sets the stage for rapidly studying defined mutations of such aggregation-prone receptors in vitro and to improve their properties by in vitro evolution using the ribosome display technology. 相似文献
100.
Vasudev P. Saraf Wolfgang G. Glasser Garth L. Wilkes James E. McGrath 《应用聚合物科学杂志》1985,30(5):2207-2224
Hydroxypropyl lignin-based thermosetting polyurethanes were synthesized with excess hexamethylene diisocyanate (HDI) and tolylene diisocyanate (TDI) by solution casting. Four polyethylene glycols (PEG) of molecular weight 400, 600, 1000, and 4000 were mixed with lignin polyol to incorporate different proportions of soft segment into the network prior to crosslinking. Neither thermal nor mechanical and limited small angle x-ray scattering (SAXS) analysis provided distinct evidence for phase separation and microstructure formation. The study examines the effect of the soft segment in relation to chain length and weight contribution on the thermal and mechanical properties of the final networks. A significant sensitivity of glass transition temperature (Tg), of swelling in DMF, and of the mechanical properties to soft segment content was observed. Some of this sensitivity must, however, be attributed to differences in crosslink density since the polyol to diisocyanate weight ratio was kept constant throughout the synthesis series. The magnitude of the change of the different properties was found to be influenced by both glycol content and glycol molecular weight. The Tg of the network decreased from 105°C to as low as 38°C (HDI), and from 158°C to 70°C (TDI), with incorporation of up to 17.8% glycol, and it was greater with lower molecular weight glycols than with higher ones at any weight fraction. Swelling in DMF increased as expected with soft segment content. Mechanical properties were affected most if HDI and lower molecular weight glycols were used. The uniformity in structure, reduction in brittleness, and considerable improvement in mechanical properties with inclusion of minor PEG contents indicates that lignin-based network polyurethanes can be synthesized with controllable performance characteristics. 相似文献