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排序方式: 共有133条查询结果,搜索用时 31 毫秒
1.
Julliane Diniz Yoneda Magaly Giro Albuquerque Ktia Zaccur Leal Peter R. Seidl Ralph A. Wheeler Scott E. Boesch Ricardo Bicca de Alencastro Maria Cecília B.V. de Souza Vitor F. Ferreira 《Journal of Molecular Structure》2006,778(1-3):97-103
Conformational analysis of nucleosides may have direct applications to the structure–activity relationship (SAR) studies and in the design of new drug candidates. Although conformational analysis may be accessed in many different ways, in this work it was performed using molecular dynamics (MD) simulation in order to study the dynamic behavior of a nucleoside derivative of 1,4-dihydro-4-oxoquinoline-3-carboxylic acid, synthesized by our group as a potential antiviral agent. The MD simulation was carried out during 10 ns in vacuum and in a box of water at two different temperatures (i.e., 300 and 600 K) using the AMBER force field. The in vacuum MD simulation results are in agreement with the crystallographic structure and with the DFT calculations of the nucleoside, revealing the anti conformer as the more stable one. The simulation in water, however, shows that both conformers may exist at 300 K, the temperature of the in vivo and in vitro assays, revealing that both the syn and anti conformers should be considered in a MD simulation study of the inhibitor–enzyme complex. Simulations are also in agreement with the NOE experiment, which shows that the anti conformer is the preferential one in DMSO-d6 solution at 298 K. 相似文献
2.
The capacity for anaerobic decolorization of a sulfonated azo dye, Congo Red, by a strain of a sulfate-reducing bacterium
was evaluated. After optimizing the growth rate of the bacteria on a simple carbon source and terminal electron acceptor pair,
lactate and sulfate, respectively, the effect of the dye concentration on their growth rate was analyzed. The decolorization
rate was affected by the dye concentration in the growth medium. The azo-bond cleavage mechanism of reductive decolorization
with the formation of benzidine was consistent with the results, as this metabolite was identified by high-performance liquid
chromatography. Several fractions of the culture medium, including lysed cell extracts, were examined for the capacity to
reduce the azo dye. This reduction capacity was found in the culture medium in which the cells had previously grown. The results
showed that the mechanism of reductive decolorization of this sulfonated azo dye was extracellular and nonenzymatic, consistent
with the production of sulfide anion by the microorganisms while growing on lactate and sulfate. The sulfide anions were the
cause of the reduction leading to the disappearance of color in the medium. To increase the rate of decolorization, the presence
of ferrous ion was also necessary together with the lactate and sulfate substrates. 相似文献
3.
Leandro Augusto Gouvêa De Godoi Carla Eloísa Diniz Dos Santos Eugenio Foresti Marcelo Zaiat Márcia Helena Rissato Zamariolli Damianovic 《International journal of environmental analytical chemistry》2019,99(9):809-823
Recent developments in wastewater treatment have led to a renewed interest to obtain elemental sulphur (S°) as a by-product from bioreactors. However, practical studies are limited by the gap of adequate analytical techniques for its determination. This paper provides a statistical study and matrix effect evaluation of an adapted spectrophotometric method for routine S° analyses in aqueous samples, based on a methodology previously described by Hart (1961). Four complex matrices were tested: domestic sewage and effluent samples from three different bioreactors. Tested performance criteria included linearity, matrix effect, limit of detection and quantification and S° recovery. Results were linear (R2 = 0.99994) in the studied range (5 to 100 mg S° L?1) and no matrix effect was observed. The accuracy was based on recovery values that varied from 100% to 106%. The colloidal S° separation and extraction protocol was also considered suitable for aqueous samples, reaching more than 99.0% of S° recovery. 相似文献
4.
Rodrigues Ana Luísa Marques Rosa Dias Maria Isabel Prudêncio Maria Isabel Russo Dulce Diniz Mariana Martins Andrea Neves César Kasztovszky Zsolt Harsányi Ildiko Szilágyi Veronika Kovács Imre Szőkefalvi-Nagy Zoltán 《Journal of Radioanalytical and Nuclear Chemistry》2022,331(9):3887-3903
Journal of Radioanalytical and Nuclear Chemistry - A contribution to the discussion about Vila Nova de São Pedro (VNSP) as a production centre of symbolic lithic artefacts, the origin of raw... 相似文献
5.
do Nascimento Ticiano Gomes Borges Arthur Luy Tavares Ferreira de Almeida Lara Mendes Ribeiro Êurica Adélia Nogueira Silva Fernanda Geny Calheiros da Costa Silva Valdemir do Nascimento Prata Ana Paula Basílio-Júnior Irinaldo Diniz Goulart Marília Oliveira Fonseca Morilla Demetrius Peireira de Freitas Johnnatan Duarte Aragão Cícero Flávio Soares 《Journal of Thermal Analysis and Calorimetry》2022,147(21):11949-11963
Journal of Thermal Analysis and Calorimetry - This work prepared and characterized microcapsule of Uncaria tomentosa (UT) in order to standardize a spray-dryer Uncaria tomentosa extract. The UT... 相似文献
6.
Celeste de Jesus Pereira Franco Oberdan Oliveira Ferreira ngelo Antnio Barbosa de Moraes Everton Luiz Pompeu Varela Lidiane Diniz do Nascimento Sandro Percrio Mozaniel Santana de Oliveira Eloisa Helena de Aguiar Andrade 《Molecules (Basel, Switzerland)》2021,26(11)
Essential oils (EOs) were extracted from Eugenia patrisii, E. punicifolia, and Myrcia tomentosa, specimens A and B, using hydrodistillation. Gas chromatography coupled with mass spectrometry (GC/MS) was used to identify the volatile constituents present, and the antioxidant capacity of EOs was determined using diphenylpicryl-hydrazyl (DPPH) and trolox equivalent antioxidant capacity (TEAC) assays. For E. patrisii, germacrene D (20.03%), bicyclogermacrene (11.82%), and (E)-caryophyllene (11.04%) were identified as the major constituents of the EOs extracted from specimen A, whereas specimen B primarily comprised γ-elemene (25.89%), germacrene B (8.11%), and (E)-caryophyllene (10.76%). The EOs of E. punicifolia specimen A contained β-Elemene (25.12%), (E)-caryophyllene (13.11%), and bicyclogermacrene (9.88%), while specimen B was composed of (E)-caryophyllene (11.47%), bicyclogermacrene (5.86%), β-pinene (5.86%), and γ-muurolene (5.55%). The specimen A of M. tomentosa was characterized by γ-elemene (12.52%), germacrene D (11.45%), and (E)-caryophyllene (10.22%), while specimen B contained spathulenol (40.70%), α-zingiberene (9.58%), and γ-elemene (6.89%). Additionally, the chemical composition of the EOs was qualitatively and quantitatively affected by the collection period. Furthermore, the EOs of the studied specimens, especially specimen A of E. punicifolia, showed a greater antioxidant activity in DPPH rather than TEAC, as represented by a significantly high inhibition percentage (408.0%). 相似文献
7.
Lidiane Diniz do Nascimento Sebastio Gomes Silva Mrcia Moraes Cascaes Kauê Santana da Costa Pablo Luis Baia Figueiredo Cristiane Maria Leal Costa Eloisa Helena de Aguiar Andrade Lênio Jos Guerreiro de Faria 《Molecules (Basel, Switzerland)》2021,26(9)
Leaves of Lippia thymoides (Verbenaceae) were dried in an oven at 40, 50 and 60 °C and the kinetic of drying and the influence of the drying process on the chemical composition, yield, and DPPH radical scavenging activity of the obtained essential oils were evaluated. The composition of the essential oils was determined with gas chromatography-mass spectrometry and gas chromatography-flame ionization detection analyses. The influence of drying on the chemical composition of the essential oils of L. thymoides was evaluated by multivariate analysis, and their antioxidant activity was investigated via the 2,2-diphenyl-1-picrylhydrazyl (DPPH) assay. The Midilli model was the most appropriate to describe the behavior of drying kinetic data of L. thymoides leaves. Thymol was the major compound for all analyzed conditions; the maximum content was obtained from fresh leaves (62.78 ± 0.63%). The essential oils showed DPPH radical scavenging activity with an average of 73.10 ± 12.08%, and the fresh leaves showed higher inhibition (89.97 ± 0.31%). This is the first study to evaluate the influence of drying on the chemical composition and antioxidant activity of L. thymoides essential oils rich in thymol. 相似文献
8.
Topological nature of in‐gap bound states in disordered large‐gap monolayer transition metal dichalcogenides 下载免费PDF全文
We propose a physical model based on disordered (a hole punched inside a material) monolayer transition metal dichalcogenides (TMDs) to demonstrate a large‐gap quantum valley Hall insulator. We find an emergence of bound states lying inside the bulk gap of the TMDs. They are strongly affected by spin–valley coupling, rest‐ and kinetic‐mass terms and the hole size. In addition, in the whole range of the hole size, at least two in‐gap bound states with opposite angular momentum, circulating around the edge of the hole, exist.Their topological insulator (TI) feature is analyzed by the Chern number, characterized by spacial distribution of their probabilities and confirmed by energy dispersion curves (energy vs. angular momentum). It not only sheds light on overcoming low‐temperature operating limitation of existing narrow‐gap TIs, but also opens an opportunity to realize valley‐ and spin‐qubits. (© 2016 WILEY‐VCH Verlag GmbH &Co. KGaA, Weinheim) 相似文献
9.
Ba0.5Sr0.5Co0.8Fe0.2O3−δ (BSCF) hollow fibers were fabricated using a phase inversion/sintering method. As oxygen permeation of BSCF hollow fibers is controlled by the rate surface exchange kinetics, catalytic Ag particles were coated on both inner and outer surfaces using chemical deposition method, as verified by SEM and EDX. The Ag coated BSCF membranes showed up to 100% increase in oxygen permeation at 700 °C, and improvements lower than 10% were measured at 950 °C as compared with unmodified membranes. It was found that Ag catalyst surface loading was non-homogenous and concentrated on the perovskite grain boundaries. As a result, lighter Ag surface loading delivered improved oxygen flux while oxygen flux reached a maximum even though in the presence of excess catalyst loading. The catalytic activity of Ag was beneficial in enhancing surface reaction kinetics up to 850 °C attributed to the spillover effect. Above this temperature, the increase in oxygen permeation rate was marginally diminished due to the reduction of the spillover effect. 相似文献
10.
Marli Roehsig Daniela Mendes Louzada de Paula Sidnei Moura Edna Maria de Albuquerque Diniz Mauricio Yonamine 《Journal of separation science》2010,33(14):2115-2122
A number of fatty acid ethyl esters (FAEEs) have recently been detected in meconium samples. Several of these FAEEs have been evaluated as possible biomarkers for in utero ethanol exposure. In the present study, a method was optimized and validated for the simultaneous determination of eight FAEEs (ethyl laurate, ethyl myristate, ethyl palmitate, ethyl palmitoleate, ethyl stearate, ethyl oleate, ethyl linoleate and ethyl arachidonate) in meconium samples. FAEEs were extracted by headspace solid‐phase microextraction. Analyte detection and quantification were carried out using GC‐MS operated in chemical ionization mode. The corresponding D5‐ethyl esters were synthesized and used as internal standards. The LOQ and LOD for each analyte were <150 and <100 ng/g, respectively. The method showed good linearity (r2>0.98) in the concentration range studied (LOQ – 2000 ng/g). The intra‐ and interday imprecision, given by the RSD of the method, was lower than 15% for all FAEEs studied. The validated method was applied to 63 authentic specimens. FAEEs could be detected in alcohol‐exposed newborns (>600 ng/g cumulative concentration). Interestingly, FAEEs could also be detected in some non‐exposed newborns, although the concentrations were much lower than those measured in exposed cases. 相似文献