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101.
Débora de Oliveira Marco Di Luccio Carina Faccio Clarissa Dalla Rosa João Paulo Bender Nádia Lipke Silvana Menoncin Cristiana Amroginski José Vladimir de Oliveira 《Applied biochemistry and biotechnology》2004,115(1-3):771-780
We studied the production of fatty acid ethyl esters from castor oil using n-hexane as solvent and two commercial lipases, Novozym 435 and Lipozyme IM, as catalysts. For this purpose, a Taguchi experimental
design was adopted considering the following variables: temperature (35–65°C), water (0–10 wt/wt%), and enzyme (5–20 wt/wt%)
concentrations and oil-to-ethanol molar ratio (1∶3 to 1∶10). An empirical model was then built so as to assess the main and
cross-variable effects on the reaction conversion and also to maximize biodiesel production for each enzyme. For the system
containing Novozym 435 as tatalyst the maximum conversion obtained was 81.4% at 65°C, enzyme concentration of 20 wt/wt%, water
concentration of 0 wt/wt%, and oil-to-ethanol molar ratio of 1∶10. When the catalyst was Lipozyme IM, a conversion as high
as 98% was obtained at 65°C, enzyme concentration of 20 wt/wt%, water concentration of 0 wt/wt%, and oil-to-ethanol molar
ratio of 1∶3. 相似文献
102.
Enzo Santaniello Silvana Casati Pierangela Ciuffreda Giuseppe Meroni Alessandro Pedretti Giulio Vistoli 《Tetrahedron: Asymmetry》2009,20(16):1833-1836
The Burkholderia cepacia lipase-catalyzed transesterification of 2-methyl-3-phenyl-1-propanol with vinyl esters proceeds with high enantioselectivity independently of the acyl chain length and the low enantioselectivity of the same reaction with 2-phenyl-1-propanol is not affected by chain length of the vinyl esters. A molecular modelling approach has been developed in order to rationalize the enzymatic results. 相似文献
103.
The present paper reports on an ultrastructural investigation of the sensilla on the antennal flagellum of the imago (SEM and TEM) and subimago (SEM) of the mayfly Rhithrogena semicolorata. Sensilla coeloconica of two different sizes, named big and small pegs, are distinguishable in both stages. The big pegs are lobe-shaped with a porous cuticle. The small pegs are more or less conical with a smooth cuticle. TEM seriate sections revealed that the big pegs are innervated by three neurons, which enter the peg. The dendrite sheath opens at the entrance to the peg and leaves the dendrites in contact with the outside through pores and pore tubules. This structure is in agreement with that reported for single-walled olfactory receptors. The small pegs may be innervated by two or four neurons. In both cases, two unbranched dendrites enter the peg and are in close association with the peg wall. These show features typical of hygroreceptors. In the small pegs innervated by four neurons, the other two neurons stop short of entering the peg, and one of them branches. This last could constitute the thermoreceptive unit. The function of the fourth neuron is unknown.The presence of olfactory sensilla in adult mayflies, such as Paleoptera, is relevant to the study of evolutionary trends in insect odour perception. Hygro–thermoreceptors are important in such fragile aquatic insects, which need a moist environment for moulting and reproduction. 相似文献
104.
Silvana Bazzoni Jan Stoví cek 《Proceedings of the American Mathematical Society》2007,135(12):3771-3781
We prove that any infinitely generated tilting module is of finite type, namely that its associated tilting class is the Ext-orthogonal of a set of modules possessing a projective resolution consisting of finitely generated projective modules.
105.
Sunto A partire da uno spazio topologico X e da un prefascio di gruppi abeliani & su X si determina, sotto npportune ipotesi, e
per ogni dimensione n, un corrispondente fibrato gruppale abeliano tale che il gruppo di omotopia legata alle fibre delle
sue sezioni globali è isomorfo alla coomologia di Čech n-dimensionale a coefficienti in & dello spazio X. 相似文献
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109.
Silvana E. Vignaduzzo Luciana Vera-Candioti Patricia M. Castellano H��ctor C. Goicoechea Teodoro S. Kaufman 《Chromatographia》2011,74(7-8):609-617
A capillary zone electrophoresis method for the simultaneous determination of pridinol mesylate (PRI) and meloxicam (MEL) employing epinastine hydrochloride and piroxicam as internal standards, was developed and optimized employing experimental design and response surface methodologies. The separation was optimally achieved in less than 2 min at 30 kV in an uncoated fused-silica capillary (41.4 cm × 75 ??m I.D.), employing an 18 mmol L?1 sodium phosphate buffer solution (pH 5.90) at 25 °C. Samples were injected in hydrodynamic mode (50 mbar, 5 s) and the analytes were spectrophotometrically detected at 200 nm. Method robustness was demonstrated by ANOVA of determinations performed under conditions slightly different from the optimum. The method was validated regarding separation selectivity (peak purity factors > 0.99), linearity and range (PRI = 17.6?C31.4 mg L?1; MEL = 66.5?C122.5 mg L?1), accuracy (PRI = 100.2?C101.9%; MEL = 98.9?C100.7%) and precision. The RSD values obtained were ??1.3% for injection repeatability and ??1.9% for intra-day precision. The limits of detection (1.0 and 0.9 mg L?1) and quantification (3.3 and 16.5 mg L?1) of PRI and MEL, respectively, were also determined. The method was successfully applied to the determination of both drugs in three brands of tablet formulations. No statistically significant differences were observed when these results were compared with those of a RP-HPLC method. 相似文献
110.
Romualdo Caputo Carla Ferreri Luigi Longobardo Domenico Mastroianni Giovanni Palumbo Silvana Pedatella 《合成通讯》2013,43(9):1223-1229
A new high yielding coupling reaction of C-2 monosubstituted 5,6-dihydro-1,4-dithiins with aldehydes is reported. In this way allylic alcohols having the cis-substituted double bond tied up by a sulfur-containing ring can be readily prepared. Subsequent stereoselective sulfur removal then affords allylic alcohols with cis-configurated double bond. 相似文献