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1.
Fábio C. Sampaio Paolo Torre Flávia M. Lopes Passos Célia Alencar de Moraes Patrizia Perego Attilio Converti 《Applied biochemistry and biotechnology》2007,136(2):165-181
To obtain in-depth information on the overall metabolic behavior of the new good xylitol producer Debaryomyces hansenii UFV-170, batch bioconversions were carried out using semisynthetic media with compositions simulating those of typical acidic
hemicellulose hydrolysates of sugarcane bagasse. For this purpose, we used media containing glucose (4.3–6.5 g/L), xylose
(60.1–92.1 g/L), or arabinose (5.9–9.2 g/L), or binary or ternary mixtures of them in either the presence or absence of typical
inhibitors of acidic hydrolysates, such as furfural (1.0–5.0 g/L), hydroxymethylfurfural (0.01–0.30 g/L), acetic acid (0.5–3.0
g/L), and vanillin (0.5–3.0 g/L). D. hansenii exhibited a good tolerance to high sugar concentrations as well as to the presence of inhibiting compounds in the fermentation
media. It was able to produce xylitol only from xylose, arabitol from arabinose, and no glucitol from glucose. Arabinose metabolization
was incomplete, while ethanol was mainly produced from glucose and, to a lesser less extent, from xylose and arabinose. The
results suggest potential application of this strain in xyloseto-xylitol bioconversion from complex xylose media from lignocellulosic
materials. 相似文献
2.
In this paper an electromechanical system is analyzed. The existence and asymptotic stability of a periodic orbit are obtained in a mathematically rigorous way as well as an expansion of the period by using an adequate small parameter. For the analytical results the main tool used is the regular perturbation theory. Some results, such as the growing of the period according to some powers of the parameters and the relation 2:1 between the period of the cart, which is a part of the electromechanical system, and the period of the current, are compatible with earlier numerical findings. 相似文献
3.
4.
Braga WS Kimura NM Luders DD Sampaio AR Santoro PA Palangana AJ 《The European physical journal. E, Soft matter》2007,24(3):247-250
The phase diagram is an interesting field of research, particularly in lyotropic liquid crystals (LLC). In this way, one of the most important phase diagrams of this LLC system was reported by Yu and Saupe. Two uniaxial (calamitic--N(C) and discotic--N(D)) and one biaxial nematic (N(B)) phases were determined by these authors. Furthermore, in this phase diagram the classical isotropic phase (I was observed at high temperature as well as a reentrant isotropic phase (I(RE)) which takes place at lower temperature. Later, this phase diagram was also studied by several authors and in all cases the I(RE)-N(C)-I phase transitions were not observed. In this work, we present a study of this phase diagram through digital image processing and refractometry optical techniques. The occurrence of these phase transitions is investigated and characterized. In addition, the order parameter is obtained based on the Vuks hypothesis from a particular point, in the range of the N(C) phase, where the absolute value of the optical birefringence (Deltan is maximum. 相似文献
5.
6.
Langanke K Martínez-Pinedo G Sampaio JM Dean DJ Hix WR Messer OE Mezzacappa A Liebendörfer M Janka HT Rampp M 《Physical review letters》2003,90(24):241102
Supernova simulations to date have assumed that during core collapse electron captures occur dominantly on free protons, while captures on heavy nuclei are Pauli blocked and are ignored. We have calculated rates for electron capture on nuclei with mass numbers A=65-112 for the temperatures and densities appropriate for core collapse. We find that these rates are large enough so that, in contrast to previous assumptions, electron capture on nuclei dominates over capture on free protons. This leads to significant changes in core collapse simulations. 相似文献
7.
CdTe quantum dots (QDs), capped with mercaptopropionic acid (MPA), were synthesized and the variation of their fluorescence properties (steady state and lifetime) with pH was assessed in solution and when immobilized in a sol-gel host. Three different sizes of CdTe QDs with excited state lifetimes ranging from 42 to 48 ns and with emission maximum at 540 nm (QD540), 580 nm (QD580) and 625 nm (QD625) were selected. The solution pH affects the maximum emission wavelength (shifts to higher wavelengths of 23, 24 and 27 nm for QD540, QD580 and QD625, respectively), the excited state lifetime and the fluorescence intensity in a reversible way. Linearization of the maximum emission wavelength variation with the pH allows the estimation of an apparent ionization constant (pKa) for each QD: 6.5 ± 0.1 (QD540), 6.1 ± 0.5 (QD580) and 5.4 ± 0.3 (QD625). The variation of the QDs fluorescence properties was further explored using confocal laser scanning microscopy allowing the implementation of a new calibration method for pH imaging in solution. QDs were successfully immobilized on the tip of an optical fiber by dip-coating using sol-gel procedure. The immobilized QDs showed a similar pH behaviour to the one observed in solution and an apparent lifetime of 80, 68 and 99 ns, respectively. The proposed QDs based methodology can be successfully used to monitor pH using wavelength encoded data in imaging and fiber optic sensing applications. 相似文献
8.
O'Brien L Petit D Lewis ER Cowburn RP Read DE Sampaio J Zeng HT Jausovec AV 《Physical review letters》2011,106(8):087204
Domain wall (DW) pinning in ferromagnetic nanowires is in general a complex process. Distortions of the DW shape make quantitative agreement between modeling and experiment difficult. Here we demonstrate pinning using nanometer scale localized stray fields. This type of interaction gives well-characterized, tailorable potential landscapes that do not appreciably distort the DW. Our experimental results are in excellent quantitative agreement with an Arrhenius-Néel model of depinning--a result only possible when the modeled potential profile agrees fully with that experienced by the DW. 相似文献
9.
In this paper, with the help of convex-like function, we discuss the duality theory for nonconvex semidefinite programming.
Our contributions are: duality theory for the general nonconvex semidefinite programming when Slater’s condition holds; perfect
duality for a special case of the nonconvex semidefinite programming for which Slater’s condition fails. We point out that
the results of Fan (Appl. Math. Lett. 18:1068–1073, 2005) can be regarded as a special case of our result. 相似文献
10.
Rangel TB Assreuy AM Pires Ade F Carvalho AU Benevides RG Simões Rda C Silva HC Bezerra MJ Nascimento AS Nascimento KS Nagano CS Sampaio AH Delatorre P Rocha BA Fernandes PM Cavada BS 《Molecules (Basel, Switzerland)》2011,16(6):5087-5103
DwL, a lectin extracted from the seeds of Dioclea wilsonii, is a metalloprotein with strong agglutinating activity against rabbit and ABO erythrocytes, inhibited by glucose and mannose. DwL was purified by affinity chromatography on a Sephadex G-50 column and ion exchange chromatography on a HiTrap SP XL column. SDS-PAGE revealed three electrophoretic bands corresponding to the α (25,634 ± 2 Da), β (12,873 ± 2 Da) and γ (12,779 ± 2 Da) chains. Protein sequencing was done by Tandem Mass Spectrometry. The primary sequence featured 237 amino acids and was highly homologous to other reported Diocleinae lectins. A complete X-ray dataset was collected at 2.0 ? for X-Man-complexed DWL crystals produced by the vapor diffusion method. The crystals were orthorhombic and belonged to the space group I222, with the unit-cell parameters a = 59.6, b = 67.9 and c = 109.0 ?. DWL differed in potency from other ConA-like lectins and was found to induce neutrophil migration in rats, making it particularly useful in structural/functional studies of this class of proteins. 相似文献