排序方式: 共有15条查询结果,搜索用时 15 毫秒
1.
Silvânia Marilene de Lima Jorge Antonio Gómez Valéria P. Barros Greice de S. Vertuan Marilda das Dores Assis Carlos Frederico de Oliveira Graeff Grégoire Jean-François Demets 《Polyhedron》2010
This work presents a new oxovanadium(IV)–cucurbit[6]uril complex, which combines the catalytic properties of the metal ion with the size-excluding properties of the macrocycle cavity. In this coordination compound, the VO2+ ions are coordinated to the oxygen atoms located at the rim of the macrocycle in slightly distorted square-pyramidal configurations, which are in fact C2v symmetries. This combination results in a size-selective heterogeneous catalyst, which is able to oxidize linear alkanes like n-pentane at room temperature, but not styrene, cyclohexane or z-cyclooctene, which are too big to enter the cucurbit[6]uril cavity. The results presented here contribute to understanding the mechanism of alkane catalytic oxidation by oxovanadium(IV) complexes. 相似文献
2.
Anna Maria Deobald Greice Tabarelli Oscar E.D. Rodrigues Antônio L. Braga 《Tetrahedron letters》2010,51(26):3364-3367
We present here our results of the efficient synthesis of azido arylselenides and azido aryldiselenides under mild conditions. Starting from nitrogen-substituted benzenes, we incorporated selenium atom at aromatic ring and obtained amino arylselenides and diselenides in satisfactory yields. Treatment of these compounds with iso-pentyl nitrite (i-C5H11ONO) and azido trimethylsilane (Me3SiN3) in THF affords a variety of azido arylselenides and diselenides in good to excellent yields. 相似文献
3.
4.
A. Donini E. Fernandez-Martinez P. Migliozzi S. Rigolin L. Scotto Lavina T. Tabarelli de Fatis F. Terranova 《The European Physical Journal C - Particles and Fields》2006,48(3):787-796
The beta beam CERN design is based on the present LHC injection complex and its physics reach is mainly limited by the maximum
rigidity of the SPS. In fact, some of the scenarios for the machine upgrades of the LHC, particularly the construction of
a fast cycling 1 TeV injector (“Super-SPS”), are very synergic with the construction of a higher γ beta beam. At the energies
that can be reached by this machine, we demonstrate that dense calorimeters can already be used for the detection of ν at
the far location. Even at moderate masses (40 kton) as the ones imposed by the use of existing underground halls at Gran Sasso,
the CP reach is very large for any value of θ13 that would provide evidence of νe appearance at T2K or NOνA (θ13≥3°). Exploitation of matter effects at the CERN to Gran Sasso distance provides sensitivity to the neutrino mass hierarchy
in significant areas of the θ13-δ plane.
PACS 14.60.Pq; 14.60.Lm 相似文献
5.
D. Tabarelli A. Vilardi C. Begliomini F. Pavani M. Turatto L. Ricci 《The European Physical Journal B - Condensed Matter and Complex Systems》2009,69(1):155-159
In human perception, exogenous noise is known to yield a masking effect, i.e. an increase of the perceptual threshold relative
to a stimulus acting on the same modality. However, somehow counter-intuitively, the opposite mechanism can occasionally occur:
a decrease of the perceptual threshold for a non-vanishing, virtuous amount of noise. This mechanism, called stochastic resonance, is deemed to provide important information about the role of
noise in the human brain. In this paper, we investigate stochastic resonance in a detection task in the auditory modality.
Normal-hearing participants were asked to judge the presence of acoustic stimuli of different intensity and superimposed to
different levels of white noise. The matrix-like outcomes of a behavioural experiment were fitted by a two-dimensional, noise-dependent
psychometric function. The fit revealed a statistically significant stochastic resonance in 43% of the experimental runs.
We conclude that, in the auditory modality, stochastic resonance is a tiny effect that, under conventional circumstances,
is largely overrun by standard masking. 相似文献
6.
de Vargas BA Argenta DF Borghetti G Koester LS Bassani VL Teixeira HF 《Journal of chromatographic science》2012,50(2):114-118
Recent studies have shown the effect of soy isoflavones in preventing skin photoaging and photocarcinogenesis, especially for genistein (GEN). Nanoemulsions have been proposed as a delivery system for GEN administration due to the low water solubility of this isoflavone. This article describes the validation of an isocratic liquid chromatography method to determine GEN in porcine ear skin layers from nanoemulsions before and after incorporation into hydrogels. The analyses are performed on a reversed-phase C18 column using a mobile phase composed of methanol-water (70:30, v/v) under acid conditions (at pH 3.0) and UV detection at 270 nm. The method is linear in the range of 0.1-10 μg/mL (r(2) > 0.999) in the presence of skin extracts. The low limit of quantitation is estimated as 0.1 μg/mL. No interferences from formulation excipients or skin layer compounds are detected. The RSD values for intra- and inter-day precision are lower than 15%. Recovery ranged from approximately 90% to 110%. The method is applied to estimate GEN retention in the skin from formulations using Franz diffusion cells. The highest amount of GEN is detected in the epidermis (185 μg/cm(2)). In conclusion, the method proved to be specific, precise, and accurate in determining GEN amounts from formulations in skin retention studies. 相似文献
7.
T. Tabarelli?de?Fatis 《The European Physical Journal C - Particles and Fields》2010,65(1-2):359-361
Active background reduction in high resolution calorimeters is a promising approach to achieve ultimate sensitivity in neutrinoless double beta decay experiments. We propose Cerenkov emission from beta rays in bolometric crystals as a viable alternative to scintillation. This novel approach could broaden the range of materials of interest for calorimetric searches of the double beta decay. We discuss the optical properties of TeO2 crystals, as a show case. 相似文献
8.
Maiara Maziero Marina Ortiz Lovatto Vinícius Victor Lorenzoni Greice Graziela Moraes Rafaela Castro Dornelles Michele Rorato Sagrillo 《Natural product research》2020,34(1):192-196
AbstractInga semialata (Vell.) C. Mart. belongs to the family Fabaceae. It is known for its therapeutic properties, highlighting its antimicrobial and antioxidant potential. The objective of the present work was to obtain crude extract leaves of Inga semialata, to identify and quantify active compounds, to evaluate the antioxidant potential of the crude extract in vitro, as well as to determine its antimicrobial activity. The crude extract was obtained by the maceration process. The identified and quantified of compounds present in the crude extract of Inga semialata was performed by high performance liquid chromatography. The evaluation of the antioxidant potential of the extract was realized by in vitro tests (DPPH, diacetate dichlorofluorescein test and nitric oxide test) and the evaluation of the antimicrobial activity was carried out using the minimum inhibitory concentration methodology. 相似文献
9.
Ernesto Schulz Lang Prof. Dr. Gelson Manzoni de Oliveira Prof. Dr. Greice Tabarelli 《无机化学与普通化学杂志》2008,634(3):416-418
Selenium and bromine were refluxed in methanol and stirred with ethylenethiourea to give yellow crystals of [(Se‐ettu)2]Br2 (ettu = ethylenethiourea). The first reported 1,2‐diselenonium dication stabilized by sulfur atoms is air unstable and yields a three‐dimensional lattice with Se+···Br?···Se+ bridges enclosing also single Se+···Br? interactions and H···Br? bonds. The air instability of [(Se‐ettu)2]Br2 probably is due to redox reactions which lead to the decomposition of ethylenethiourea with precipitation of sulfur. 相似文献
10.