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排序方式: 共有71条查询结果,搜索用时 31 毫秒
1.
Two series of monoionic (M) kaolinites (M = H(+), Ca(2+), Cu(2+), Zn(2+), Al(3+), and Fe(3+)) were prepared from a natural Brazilian clay (S?o Sim?o clay, SP): series A, dried under vacuum at 25 degrees C, and series B, dried under vacuum at 25 degrees C. The natural clay was characterized by elemental analysis, cation exchange capacity, X-ray diffractometry, differential thermal analysis, and surface area measurements (BET). The interactions of M,M-dimethylacetamide and pyridine with these (M) kaolinites were studied by adsorption isotherms, titration calorimetry, and infrared spectroscopy (for pyridine only). The results indicated a coordinative interaction between M,M-dimethylacetamide and (M) kaolinites. For the interactions between pyridine and (M) kaolinites, the formation of hydrogen bonds (M = Al(3+), Fe(3+)), hydrogen and coordinative bonds (M = Cu(2+), Zn(2+)), and ionic pairs (M = H(+), Ca(2+)) was observed. For the pyridine-(Cu) kaolinite system, a substitution of water coordinated to Cu(2+) by pyridine was established. 相似文献
2.
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
3.
Gomes João Pedro Agra Mourão Eduard David Simões dos Anjos Janaina Versiani de Alencar Filho Edilson Beserra 《Structural chemistry》2020,31(6):2501-2512
Structural Chemistry - In this paper, we present a quantitative structure–activity relationships modelling for two series of heterocyclic synthetic compounds with larvicidal activity against... 相似文献
4.
Alencar Raymundo; Aron Richard; Galindo Pablo; Zagorodnyuk Andriy 《Bulletin London Mathematical Society》2003,35(1):55-64
The authors study the algebra of uniformly continuous holomorphicsymmetric functions on the ball of lp, investigating in particularthe spectrum of such algebras. To do so, they examine the algebraof symmetric polynomials on lp-spaces, as well as finitely generatedsymmetric algebras of holomorphic functions. Such symmetricpolynomials determine the points in lp up to a permutation. 相似文献
5.
Cristofher Victor Vivas Palomares Yan Borges Barreto Natalia Marchesan Bexiga Sergio Hiroshi Toma Jonnatan Julival dos Santos Koiti Araki Adriano Mesquita Alencar Antonio Carlos Bloise 《Particle & Particle Systems Characterization》2023,40(4):2200191
The macrophage time-dependent metabolic profile changing basal metabolism triggered by nanoparticles can be obtained and used to improve wound healing treatments. Herein this study demonstrates that metabolic status responds systematically to cytotoxicity manipulation, providing an interesting way of cellular control. Nuclear magnetic resonance (NMR) based metabolomics and cytotoxic assays are used to study RAW 264.7 cells exposed to AgNPs at different concentrations and incubation times. Cytotoxicity data show a slight decrease in cellular expansion rates accompanied by morphological changes in cells. Metabolomics show that despite the glycolytic activity of treated and non-treated cells remains unchanged; however, only the treated cells present a rich Citrate environment signaling up-regulation of Tricarboxylic-Acid-Cycle (TCA). Cells choose aerobic routes instead of anaerobic ones to produce energy and self-regulate their amino acid metabolism to balance TCA. Choline metabolism is down-regulated once its sub-products, Betaine and Glycine, are reduced, thus compromising Creatine synthesis. Phospholipid metabolism is down-regulated due to the decreasing of Phosphocholine and Sn-Glycerol-3-PC, in agreement with the cytotoxicity results. Pyroglutamate decreases in treated cells, signaling different levels of oxidative stress. These analytical tools can characterize AgNPs-treatments, even distinguishing dose and time dependencies. Therefore, the fine-tuning of exposition parameters can modulate cellular activity to achieve better wound healing. 相似文献
6.
I. Alencar J. Ruiz‐Fuertes K. Schwartz C. Trautmann L. Bayarjargal E. Haussühl B. Winkler 《Journal of Raman spectroscopy : JRS》2016,47(8):978-983
The formation conditions and dynamics of Ca colloids and point defects that appear in irradiated single crystals of CaF2 were investigated by Raman spectroscopy. The intensity changes in the Raman spectra because of the presence of different concentrations of point defects and Ca colloids that emerged in CaF2 after irradiation with 2.2 GeV Au ions were used to study their distribution and stability under illumination with three laser wavelengths (473, 532 and 633 nm) at different output powers (2 to 200 mW). A damage saturation at a fluence of 6 × 1011 ion cm−2 was observed. The dependence of the spectral changes on the ion fluence can be described by a core/halo damage cross‐section model. A radius of 13–18 nm was obtained for the outer (halo) cylinder, in agreement with previous swelling studies. Illuminations of irradiated samples with blue (473 nm) and green (532 nm) lasers were found to be extremely efficient in bleaching the samples, while illumination with a red (633 nm) laser did not lead to a sample recovery. This indicates that the bleaching process is governed by recombination of point defects that have to overcome an energy barrier. Typical time constants for the processes involved are presented. Copyright © 2016 John Wiley & Sons, Ltd. 相似文献
7.
L. A. Farias D. I. T. Favaro V. A. Maihara Vasconcellos M. B. A. L. K. Yuyama J. P. L. Aguiar F. J. Alencar 《Journal of Radioanalytical and Nuclear Chemistry》2006,270(1):217-223
Summary Daily dietary intake of Hg and some essential elements in diets of children from communities in the Jaú National Park, Amazon
region, were assessed. Diet samples were analyzed for total Hg content using cold vapor atomic absorption spectrometry and
Ca, Fe, K, Na, Se and Zn contents by instrumental neutron activation analysis. The weekly tolerable provisional intake for
Hg in the communities studied varied from 13 to 57 mg of Hg per kg of body weight, exceeding the limit of 5 mg . kg-1 set by the WHO. Comparison of the daily dietary intake values to the new Dietary Reference Intakes (4-8 years), showed prevalence
of inadequacy. 相似文献
8.
Josepha Yohanna de Jesus Eliane Santos de Carvalho Dantas Mairim Russo Serafini Paula dos Passos Menezes Juliana Cordeiro Cardoso Ricardo Luiz Cavalcanti Albuquerque-Jr Jivaldo do Rosário Matos Juliana Ferreira de Oliveira Irwin Rose Alencar de Menezes Francilene Amaral da Silva Adriano Antunes de Souza Araújo 《Journal of Thermal Analysis and Calorimetry》2016,123(3):2003-2012
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We want to thank Detang Zhou for kindly pointing us our mistake. 相似文献