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81.
82.
Pinheiro-Sant'ana HM Guinazi M Oliveira Dda S Della Lucia CM Reis Bde L Brandão SC 《Journal of chromatography. A》2011,1218(47):8496-8502
The objective of this study was to optimize a method to investigate the occurrence and to quantify the full isomeric composition of vitamin E (α-, β-, γ- and δ-tocopherols and tocotrienols) in 6 vegetables (raw and cooked), 3 herbs/spices, raw and cooked eggs, vegetable oils (canola, olive and soybean), flaxseed and sorghum (flour and seeds) and soy (flour) by HPLC with fluorescence detection. Different conditions of extraction and analysis were tested. The optimized method consisted of direct extraction with solvent (hexane:ethyl acetate, 85:15, v/v). For analysis normal phase column was used with mobile phase consisting of hexane:isopropanol:acetic acid (98.9:0.6:0.5) with isocratic elution and fluorescence detection. Excellent separation of all isomers was obtained along with adequate quantification in the foods analyzed. Recovery rates of standards ranged from 91.3 to 99.4%. The linearity range for each isomer varied from 2.5 to 137.5 ng/mL (R2 greater than 0.995 in all cases). Detection limits ranged from 21.0 to 48.0 ng/mL for tocopherols and from 56.0 to 67.0 ng/mL for tocotrienols, while quantification limits ranged from 105.0 to 240.0 ng/mL for tocopherols and from 280.0 to 335.0 ng/mL for tocotrienols. The optimized method was considered simple, fast and reliable, and also preserved vitamin E isomers when compared to validated methods involving saponification. 相似文献
83.
84.
Rubens R Santos Jr Alexandrina Sartori Deison S Lima Patrícia RM Souza Arlete AM Coelho-Castelo Vania LD Bonato Célio L Silva 《Journal of immune based therapies and vaccines》2009,7(1):4-12
Background
Our group previously demonstrated that a DNA plasmid encoding the mycobacterial 65-kDa heat shock protein (DNA-HSP65) displayed prophylactic and therapeutic effect in a mice model for tuberculosis. This protection was attributed to induction of a strong cellular immunity against HSP65. As specific immunity to HSP60 family has been detected in arthritis, multiple sclerosis and diabetes, the vaccination procedure with DNA-HSP65 could induce a cross-reactive immune response that could trigger or worsen these autoimmune diseases. 相似文献85.
Gizelle A.B. Vieira Telma L.G. Lemos Marcos Carlos de Mattos Maria da Conceicão F. de Oliveira Vânia M.M. Melo Gonzalo de Gonzalo Vicente Gotor-Fernández Vicente Gotor 《Tetrahedron: Asymmetry》2009,20(2):214-219
Straightforward synthetic strategies for the preparation of optically active Mugetanol isomers have been developed through different independent chemoenzymatic routes implying the use of either alcohol dehydrogenases in aqueous media or lipases in organic solvents coupled with a catalytic hydrogenation process. Among the alcohol dehydrogenases tested, ADH RS1 showed the best activities in the bioreduction of 4-isopropylacetophenone. The lipase from Pseudomonas cepacia (PSL-C I) reached high activity values in the lipase-catalyzed transesterification of 4-isopropylphenyl)ethanol, while Candida antarctica lipase B showed the best stereopreference in the acetylation of 4-isopropylcyclohexylethanol. 相似文献
86.
87.
The Schlieren effect in flow-injection analysis is critically examined. Effects of sample constitution, injection volume, coil lengths, flow-rates, confluent stream addition and temperature are studied and practical implications in flow-injection design with and without the stopped-flow approach are discussed. For Schlieren compensation, a diode-array spectrophotometer is used and non-specific absorbance subtraction is exploited: the incident light passes through the flowing sample, the emergent light is dispersed, the intensities of two selected monochromatic beams are measured simultaneously by separate detectors and real-time subtraction of the wavelength-independent noise is achieved. The sensitivity and measurement precision improve after application of the subtraction algorithm. The potential, limitations and practical applications of the method are discussed. 相似文献
88.
This paper concerns the study of the interaction between aging and plasticity in a 2024 aluminum-copper alloy. The framework of thermodynamics of irreversible processes is used to introduce the effect of aging in the constitutive equations by means of an internal variable. These constitutive equations are checked by comparing the prediction of uniaxial tests with the experimental responses. They are also introduced into a finite element code, and the evolution of notched structures shows that the coupling between aging and plasticity can strongly modify the distribution of the stresses. 相似文献
89.
Inelastic scattering induces dephasing in mesoscopic systems. An analysis of previous models to simulate inelastic scattering
in such systems is presented and a relatively new model based on wave attenuation is introduced. The problem of Aharonov-Bohm
(AB) oscillations in conductance of a mesoscopic ring is studied. We show that the conductance is symmetric under flux reversal
and the visibility of AB oscillations decays to zero as a function of the incoherence parameter, signaling dephasing. Further
the wave attenuation model is applied to a fundamental problem in quantum mechanics, that of the conditional (reflection/transmission)
times spent in a given region of space by a quantum particle before scattering off from that region. 相似文献
90.
Adriano L. A. Mattos Diego Lomonaco Morsyleide de Freitas Rosa Men de sá S. M. Souza Filho Edson N. Ito 《Composite Interfaces》2018,25(2):93-107
This work is aimed at the one-step chemical modification of the surface of cashew wood flour particles using the technical grade cashew nut shell liquid (CNSL). The goal is to develop an alternative way to introduce chemically active sites on the surface of the particles, which allows the addition of new functionalities to such particles. The influence of time and temperature and catalyst on the substitution of lignocellulosic hydroxyls with cardanol/cardol urethane derivatives was evaluated by thermogravimetric analysis, scanning electron microscopy, Fourier-transform infrared spectroscopy (FTIR), and contact angle measurements. The mechanical behavior of the modified particles in polypropylene composites was also evaluated by mechanical testing and dynamic mechanical thermal analysis. The FTIR, thermogravimetry, and contact angle results indicated changes on the particle surface, and the mechanical and thermomechanical behavior of the mercerized and modified particles in the composites was found to be similar. These results point that the CNSL approach is a viable way to chemically modify cashew wood flour particle surfaces, while maintaining their properties. 相似文献