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181.
Yanis Caro Pierre Villeneuve Michel Pina Max Reynes Jean Graille 《Journal of the American Oil Chemists' Society》2000,77(8):891-902
The protein contents in crude latices from various varieties of papaya (Carica papaya) and their catalytic activities in proteolysis, lipolysis, and interesterification reactions were studied with regard to
the variety, the geographic location of cultures, and the frequency of fruit tapping. Biocatalytic activities of these raw
materials were compared to several commercially available crude and purified preparations of papain. These investigations
were carried out in order to have a better physicochemical characterization of these raw materials, to select the adequate
papaya latex for protein or lipid bioconversions, and to valorize them on an industrial scale. For the purified preparations
of papain, only proteolytic activity was obtained. All crude papaya latices exhibit proteolytic, lipolytic, and interesterification
activities, and no relationship between the proteolytic and lipolytic activities was observed. The high multiple correlation
coefficient (R) on the order of R=0.93–0.99, obtained from the regression analysis for the lipolytic and interesterification activities for all crude papaya
latices investigated suggested that there was a correlation between these enzyme activities. However, for the same lipase
preparation, the interesterification activity differed substantially depending on the type of interesterification reaction. 相似文献
182.
Besson Michèle Blackburn Andy Gallezot Pierre Kozynchenko Oleksander Pigamo Anne Tennison Steve 《Topics in Catalysis》2000,13(3):253-257
Carbons derived from phenolic resins were used as catalysts for the aqueous phase oxidation of cyclohexanone at 140°C under air pressure. The reaction yielded mainly adipic, glutaric and succinic acids. The samples were modified by heat treatments in CO2, air or N2 at different temperatures and characterized to determine their surface area and porosity and to evaluate the functional groups on the surface. Treatments under CO2 or air increased the oxidation activity. The selectivity to adipic acid was maximum (33%) after activation in air which greatly increased the surface concentration of oxygen-containing functional groups. However, it was not possible to attribute the selectivity to specific acidic, neutral or basic groups present at the surface of carbons. This revised version was published online in June 2006 with corrections to the Cover Date. 相似文献
183.
François Malherbe Jean‐Pierre Besse Steven R. Wade Warren J. Smith 《Catalysis Letters》2000,67(2-4):73-79
The catalytic activity of a series of mixed oxides obtained by the thermal decomposition of hydrotalcite‐like precursors was
assessed for the alkoxylation of n-butanol with ethylene oxide. The calcination products of a decavanadate intercalated magnesium–aluminium layered double hydroxide
were shown to possess extremely high activity for the alkoxylation reaction achieving up to 100% conversion in batch reaction.
In all cases, the catalysts exhibit a much higher selectivity towards the monoglycol adduct than that obtained with the industrial
catalyst.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
184.
Chapdelaine Pierre; Moisset Pierre-Alain; Campeau Philippe; Asselin Isabelle; Vilquin Jean-Thomas; Tremblay Jacques P. 《Protein engineering, design & selection : PEDS》2000,13(9):611-615
Transfection and transduction studies involving the use of thefull-length dystrophin (11 kb) or the truncated mini-gene (6kb) cDNAs are hampered by the large size of the resulting viralor non-viral expression vectors. This usually results in verylow yields of transgene-expressing cells. Moreover, the detectionof the few transgene-expressing cells is often tedious and costly.For these reasons, expression vectors containing the enhancedgreen fluorescent protein (EGFP) fused with the N-termini ofmini- and full-length human dystrophin were constructed. Theseconstructs were tested by transfection of Phoenix cells withEffectene, resulting after 48 h in a green fluorescent signalin 20% of cells. Analysis of the cell extracts by immunoblottingwith the use of a monoclonal antibody specific to the dystrophinC-terminus confirmed the expression of EGFPmini- (240kDa) and EGFPfull-length human dystrophin (450 kDa) fusionproteins. Moreover, following the in vivo electroporation ofthe plasmids containing the EGFPmini- and full-lengthdystrophin in mouse muscles, both fluorescent proteins wereobserved in cryostat sections in their normal location underthe plasma membrane. This indicates that the fusion of EGFPto dystrophin or mini-dystrophin did not interfere with thenormal localization of the protein. In conclusion, the fusionof EGFP provides a good tool for the search of the best methodsto introduce mini- or full-length dystrophin cDNA in the cells(in vitro) or muscle fibers (in vivo) for the establishmentof a treatment by gene therapy of Duchenne muscular dystrophypatients. 相似文献
185.
186.
Sbastien Bessenet Viviane Renaudin Jean‐Pierre Leclerc Jean‐Marie Hornut 《加拿大化工杂志》2000,78(3):486-494
A hydrodynamic study of a new graphite evaporator has been performed. In this exchanger the fluid flows as a thin film on a spirally wound fin which forms a spiral staircase inside a tube. The slope θm of the spirally wound fin is modifiable. The residence time distribution (RTD) of the film was measured for different fin slopes θm and several film flowrates mf. The flow pattern was then modelled thanks to the DTS software as a cascade of perfect mixed cells and the mean residence time τm was calculated. The evolution of τm as a function of θm and mf is accurately represented by a power law relation. 相似文献
187.
Bérengère Du Roizel Ana M. P. Henriques Alan J. Pearce Pierre Sinaÿ 《Israel journal of chemistry》2000,40(3-4):317-324
Carbohydrate-based vinyl acetals (5-hex-enopyranosides) undergo reductive rearrangement with triisobutylaluminum (TIBAL) to afford highly functionalized cyclohexanes in which both the aglycon and anomeric stereochemistry are retained. Here, we report the first application of this process to the rearrangement of hex-5-enopyranosides of sucrose in which the interglycosidic oxygen atom of the vinyl acetal system links the anomeric centers of both monosaccharide units. The sucrose-derived 5-hex-enopyranoside 1 undergoes smooth reductive rearrangement with TIBAL to afford the (1 → 2′) ether-linked pseudo-disaccharide 2 in 34% yield. The rearrangement is accompanied by some loss of stereochemical integrity at C-2′ due to a competitive exo-cleavage of the interglycosidic (O-C2′) bond, hence diastereomers at C-2′ are also obtained in 12% yield. The 4-O-allyl-protected sucrose-5-ene 3 is similarly transformed into the corresponding (1 → 2′) ether-linked pseudo-disaccharide 4 , illustrating the compatibility of the allyl group with the TIBAL reaction conditions. 相似文献
188.
Amy E. Childress Pierre Le-Clech Joanne L. Daugherty Caifeng Chen Greg L. Leslie 《Desalination》2005,180(1-3):5-14
In order to gain insight into membrane fiber failure (i.e., loss of integrity), properties of five hollow fiber membranes and four hollow fiber modules were evaluated. Specifically, membrane material, membrane symmetry, fiber modulus of elasticity, fiber diameter and thickness, module potting technique, module flow pattern (inside-out or outside-in), and coliform breakthrough were investigated. The approach combined evaluation of the above properties with mathematical modeling of structure-fluid interactions to comprehensively evaluate the properties most important for maintaining hollow fiber membrane integrity. Tensile strength testing revealed that the strongest fiber was an asymmetric polyacrylonitrile membrane fiber. The weakest fiber was a symmetric polyethylene membrane fiber. Pilot plant testing on the four membrane modules revealed that membrane symmetry may be a more important factor than potting technique for hollow fiber integrity. Results from the SEM and tensile testing were used as input to a finite element analysis model used to evaluate time-dependent structure-fluid interactions. It was found that additional stresses at the juncture of the potting material and the hollow fiber membranes exist. These stresses likely lead to the formation of fractures. 相似文献
189.
Stability of ruthenium catalysts supported on TiO2 or ZrO2 in catalytic wet air oxidation 总被引:1,自引:0,他引:1
The stability of ruthenium catalysts supported on TiO2 and ZrO2 were studied in the wet air oxidation of aqueous solution of succinic and p-hydroxybenzoic acids taken as model effluent and on real effluents from the paper-pulp industry. Catalyst recycling experiments were conducted in batch reactor and long-term stability tests were conducted in trickle-bed reactor. In all experiments, ruthenium and support materials were perfectly stable to leaching, sintering and fouling. Ruthenium catalysts experienced a weak deactivation as they were exposed to air, e.g., in recycling experiments however the loss of activity occurred only after the first exposure and was completely reversible upon catalyst reduction. The deactivation was attributed to an over-oxidation of the catalyst surface particularly noticeable in the case of very small Ru-clusters (1 nm). 相似文献
190.
Catalytic ethylene oligomerization represents a topic of considerable current academic and industrial interest, in particular for the production of linear alpha-olefins in the C4-C10 range, whose demand is growing fast. Identifying and fine-tuning the parameters that influence the activity and selectivity of metal catalysts constitute major challenges at the interface between ligand design, coordination/organometallic chemistry, and homogeneous catalysis. In this Account, we show how comparative studies aiming at modulating the coordinating properties of functional ligands for a metal, such as nickel, which is used in industrial processes, lead to beneficial effects in catalytic ethylene oligomerization. 相似文献