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981.
Gilberto Siqueira Sandra Tapin-Lingua Julien Bras Denilson da Silva Perez Alain Dufresne 《Cellulose (London, England)》2011,18(1):57-65
In a previous work (Siqueira et al. 2010b) the preparation of cellulosic nanoparticles from sisal fibers using different processing routes, viz. a combination of mechanical shearing, acid and enzymatic hydrolysis was reported. It was shown that the pre-enzymatic hydrolysis treatment of bleached sisal pulp helps the preparation of well individualized rod-like nanocrystals. An amorphous polymer (natural rubber—NR) was chosen as model matrix to investigate the effect of these nanoparticles on the thermo-mechanical properties of nanocomposites. Both tensile tests and dynamic mechanical analyses showed improved stiffness for all nanocomposites. The enzymatic treatment allowed production of a huge range of cellulosic nanoparticles which provided completely different mechanical properties to NR matrix. 相似文献
982.
R. A. G. Silva A. T. Adorno A. G. Magdalena T. M. Carvalho M. Stipcich A. Cuniberti M. L. Castro 《Journal of Thermal Analysis and Calorimetry》2011,103(2):459-463
In this study the effect of Ag additions on the thermal behavior of the Cu–22.55 at.%Al alloy was studied using electrical
resistivity measurements, in situ X-ray diffractometry, differential scanning calorimetry, and optical microscopy. The results
indicated that Ag additions do not change the phase transformations sequence in the studied alloys, but modify its critical
temperatures due to a change on entropy of system. It was verified that at the cooling rate of 10 K/min the decomposition
of β phase into (α + γ1) is incomplete, but for lower cooling rates than 1.0 K/min this reaction is completed. 相似文献
983.
Sílvia S. P. R. Almeida Joo J. R. Fraústo Da Silva Armando J. L. Pombeiro 《Journal of organometallic chemistry》1993,450(1-2)
Treatment of a THF solution of trans-[ReCl(N2)(dppe)2] (dppe = Ph2PCH2CH2PPh2) with a 1-alkyne HCCR (R =tBu, CO2Me, CO2Et, or C6H4Me-4), in the presence of Tl[BF4]/[NH4][BF4], under sunlight, affords the corresponding carbyne-fluoro complexes trans-[ReF(CCH2R)(dppe)2][BF4] in an unprecedented single-pot synthesis. Further reaction with [BU4N]OH leads to the vinylidenefluoro compounds trans-[ReF(=C=CHR)(dppe)2] (R = CO2Me, CO2Et, or C6H4Me-4). 相似文献
984.
The Kalman filter algorithm was used to process data obtained in the simultaneous determination of species following first- and second-order kinetics. The performance of the algorithm in the quantification of chemical components from simulated data was assessed, and the influence of various parameters involved was estimated. The algorithm was applied to the resolution of cysteine-ascorbic acid and glutathione-ascorbic acid mixtures where the ascorbic acid followed pseudo first-order kinetics and the amino acids second-order kinetics in the reaction with the copper(II)-neocuproine system. Some features of the determinations (namely, afforded concentration ratios, accuracy and precision) are discussed. 相似文献
985.
Silva NL Betancur GJ Vasquez MP Gomes Ede B Pereira N 《Applied biochemistry and biotechnology》2011,163(7):928-936
Current research indicates the ethanol fuel production from lignocellulosic materials, such as residual wood chips from the
cellulose industry, as new emerging technology. This work aimed at evaluating the ethanol production from hemicellulose of
eucalyptus chips by diluted acid pretreatment and the subsequent fermentation of the generated hydrolysate by a flocculating
strain of Pichia stipitis. The remaining solid fraction generated after pretreatment was subjected to enzymatic hydrolysis, which was carried out simultaneously
with glucose fermentation [saccharification and fermentation (SSF) process] using a strain of Saccharomyces cerevisiae. The acid pretreatment was evaluated using a central composite design for sulfuric acid concentration (1.0–4.0 v/v) and solid to liquid ratio (1:2–1:4, grams to milliliter) as independent variables. A maximum xylose concentration of 50 g/L
was obtained in the hemicellulosic hydrolysate. The fermentation of hemicellulosic hydrolysate and the SSF process were performed
in bioreactors and the final ethanol concentrations of 15.3 g/L and 28.7 g/L were obtained, respectively. 相似文献
986.
Clovis Piovezan Fábio da Silva Lisboa Fábio Souza Nunes Sueli Maria Drechsel 《Transition Metal Chemistry》2011,36(1):79-85
We report the reactivity of three binuclear non-heme Fe(III) compounds, namely [Fe2(bbppnol)(μ-AcO)(H2O)2](ClO4)2 (1), [Fe2(bbppnol)(μ-AcO)2](PF6) (2), and [Fe2(bbppnol)(μ-OH)(Cl)2]·6H2O (3), where H3bbppnol = N,N′-bis(2-hydroxybenzyl)-N,N′-bis(2-methylpyridyl)–1,3-propanediamine-2-ol, toward the hydrolysis of bis-(2,4-dinitrophenyl)phosphate as models for phosphoesterase
activity. The synthesis and characterization of the new complexes 1 and 3 was also described. The reactivity differences observed for these complexes show that the accessibility of the substrate
to the reaction site is one of the key steps that determinate the hydrolysis efficiency. 相似文献
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