排序方式: 共有10条查询结果,搜索用时 15 毫秒
1
1.
Nelson Durán Klaus Zinner Roberto Casadei de Baptista Carmen C. C. Vidigal Giuseppe Cilento 《Photochemistry and photobiology》1976,24(4):383-388
Abstract— The thiophenyl ester of indole-3-acetic acid and indole-3-acetonitrile produce chemiluminescence in aerated dimethylsulfoxide in the presence of potassium t -butoxide. The emitter is the aromatic aldehyde. In the case of acetonitrile, the other product expected from the cleavage of an intermediate dioxetane, cyanate/isocyanate, has also been identified. Other auxins also chemiluminesce under similar conditions, but the emitters have not been properly identified.
These systems are models for the peroxidase catalyzed oxidation of indole-3-acetic acid to indole-3-carboxaldehyde and as such support the earlier inference (Vidigal et al , 1975) that the excited aldehyde is generated in the enzymic process.
An additional result is the observation of an exciplex between excited indole-3-carboxaldehyde and the thiophenylester of indole-3-acetic acid. This appears to be the first case of chemical generation of an exciplex by a route other than radical ion reaction, presumably by the dioxetane route. 相似文献
These systems are models for the peroxidase catalyzed oxidation of indole-3-acetic acid to indole-3-carboxaldehyde and as such support the earlier inference (Vidigal et al , 1975) that the excited aldehyde is generated in the enzymic process.
An additional result is the observation of an exciplex between excited indole-3-carboxaldehyde and the thiophenylester of indole-3-acetic acid. This appears to be the first case of chemical generation of an exciplex by a route other than radical ion reaction, presumably by the dioxetane route. 相似文献
2.
A sequential injection lab-on valve (SI-LOV) method for the enzymatic determination of hydrogen peroxide was developed. The spectrophotometric assay is based on the reaction between hydrogen peroxide and ABTS (2,2′-Azino-bis(3-Ethylbenzothiazoline 6-sulfonic acid)) in the presence of the enzyme HRP (horseradish peroxidase). The produced oxidized ABTS is measured at 410 nm. The sample consumption was 15 µL/assay and the consumption of HRP and ABTS was 34.6 mg L− 1 and 0.06 g L− 1, respectively with a determination rate of 45 h− 1.Relative deviations lower than 9.0% were found when the results were compared to those obtained by the reference procedure in the analysis of bleaches and disinfection solutions for contact lenses. With the incorporation of an in-line dilution (dialysis) process, was possible to attain a response range up to 342 mg L− 1 of hydrogen peroxide. The developed method was applied to monitor on-line of the disinfection–neutralization process of contact lenses. The study of two different one-step systems for cleaning contact lenses demonstrated that the neutralization of the hydrogen peroxide is completed within 6 h as recommended by the manufactures. The developed flow method was proved to be a useful tool for monitoring the dynamic process of disinfection–neutralization. 相似文献
3.
A sequential injection lab-on-valve (SI-LOV) system was used to develop a new methodology for the determination of iron in wine samples exploiting the bead injection (BI) concept for solid phase extraction and spectrophotometric measurement. Nitrilotriacetic Acid (NTA) Superflow resin was used to build the bead column of the flow through sensor. The iron (III) ions were retained by the bead column and react with SCN− producing an intense red colour. The change in absorbance was monitored spectrophotometrically on the optosensor at 480 nm. It was possible to achieve a linear range of 0.09-5.0 mg L−1 of iron, with low sample and reagent consumption; 500 μL of sample, 15 μmol of SCN−, and 9 μmol of H2O2, per assay. The proposed method was successfully applied to the determination of iron in wine, with no previous treatment other than dilution, and to other food samples. 相似文献
4.
ELECTRONICALLY EXCITED SPECIES IN THE PEROXIDASE CATALYZED OXIDATION OF INDOLEACETIC ACID. EFFECT UPON DNA AND RNA 总被引:1,自引:0,他引:1
Carmen C. C. Vidigal Adelaide Faljoni-Alário Nelson Durán Klaus Zinner Yoshiaki Shimizu Giuseppe Cilento 《Photochemistry and photobiology》1979,30(1):195-198
Abstract— The electronically excited species generated in the peroxidase (oxidase) catalyzed oxidation of the plant hormone indole-3-acetic acid is an excited state of indole-3-carboxaldehyde.
The chemiexcited species is able to induce in DNA the same alterations as observed with light or with enzyme-generated triplet acetone. The chemiexcited species can also alter r-RNA. 相似文献
The chemiexcited species is able to induce in DNA the same alterations as observed with light or with enzyme-generated triplet acetone. The chemiexcited species can also alter r-RNA. 相似文献
5.
A collection of 39 metallic artefacts recovered in archaeological sites of Southern Portugal was studied by micro‐EDXRF to identify their compositions and the use of metal among ancient communities. Artefacts presented different typologies such as tools (e.g. awls, chisels and a saw) and weapons (e.g. daggers and arrowheads) mostly belonging to 2500–2000 BC. The results show copper with variable amounts of As and very low content of other impurities, such as Fe, Pb or Sb. Moreover, nearly half of the collection is composed by arsenical copper alloys, and an association was found between arsenic content and typology because the weapons group (mostly daggers) present higher values than tools (mostly awls). These results suggest some criteria in the selection of arsenic‐rich copper ores or smelting products. Finally, the compositions were compared to those of other collections from neighbouring regions and different chronology to determine metallurgical parallels. Copyright © 2015 John Wiley & Sons, Ltd. 相似文献
6.
Paiva LC Vidigal PG Donatti L Svidzinski TI Consolaro ME 《Micron (Oxford, England : 1993)》2012,43(2-3):497-502
Vulvovaginal candidiasis (VVC) is a very common cause of fungal infection that remains a significant problem worldwide, especially concerning its complex pathogenicity. Biofilm dynamics from vaginal isolates requires further investigation. Different assays, such as cell surface hydrophobicity (CSH), biofilm production, fungal metabolism by 2H-tetrazolium-5-carboxanilide (XTT) and phenazine methosulfate (PMS), scanning electron microscopy (SEM) and confocal scanning laser microscopy (CSLM) were used in order to determine the ability of five Candida species isolates from VVC patients to form in vitro biofilms and their ultrastructural characteristics. All yeasts demonstrated the ability to produce biofilm and showed viability up to 48 h after the completion of assay, confirmed by SEM and CSLM, but differences were observed between them. SEM and CSLM also revealed that all VVC isolates adhered only in blastoconidia form, except for Candida parapsilosis. Even though, only one isolate from each Candida species has been used, the results of high biofilm formation, metabolic activity and CSH showed by Candida albicans and C. parapsilosis, as well as by the ultrastructural characteristics, suggest that these species exhibit greater ability of adherence in relation to the others. Ours results support the theory that virulence potential is multifactorial and that other factors not evaluated in this study could be involved in the CVV physiopathogeny. 相似文献
7.
S. D. da Cunha R. R. Vidigal L. R. da Silva R. Dickman 《The European Physical Journal B - Condensed Matter and Complex Systems》2009,72(3):441-449
We study diffusion of particles in large-scale simulations of one-dimensional
stochastic sandpiles, in both the restricted and unrestricted versions.
The results indicate that the diffusion constant scales in the same manner as the
activity density, so that it represents an alternative definition of an order parameter.
The critical behavior of the unrestricted sandpile is very similar to that of its
restricted counterpart, including the fact that a data collapse of the order parameter as a function of
the particle density is possible, but with a narrow scaling region.
We also develop a series expansion, in inverse powers of the density,
for the collective diffusion coefficient in a variant
of the stochastic sandpile in which the toppling rate at a site with n particles is n(n-1),
and compare the theoretical prediction with simulation results. 相似文献
8.
Richard Marins da Silva Valeria Monteze Guimarães Lizzy Ayra Alcântara Veríssimo Márcia Cristina Teixeira Ribeiro Vidigal Valéria Paula Rodrigues Minim Luis Antonio Minim 《Journal of separation science》2022,45(2):401-410
This study focused on the extraction, purification, and physicochemical characterization of γ-conglutin, a protein present in lupin seeds with properties of reducing blood glucose levels. Total protein was extracted with an alkaline-saline solvent, followed by isoelectric precipitation. Chromatographic purification of the precipitated fraction was performed using a cation exchange supermacroporous cryogel column. Electrophoresis of the eluted fraction from chromatography presented a single band of ∼48 kDa under non-reducing conditions (two bands of ∼30 and ∼17 kDa, under reducing conditions) confirming the success of the purification protocol. Liquid chromatography-tandem mass spectrometry analysis confirmed the identity of the protein as γ-conglutin. The purified γ-conglutin had an isoelectric point of 7.51, β-sheets prevailing as a secondary structure, and denaturation temperature close to 68°C. The outcome of this work showed that γ-conglutin was obtained with a high degree of purity. The proposed purification protocol is simple and can be easily scaled up. 相似文献
9.
We derive the first four terms in a series for the order paramater (the stationary activity density ) in the supercritical regime of a one-dimensional stochastic sandpile; in the two-dimensional case the first three terms are reported. This is done by reorganizing the pertubation theory derived using a path-integral formalism [Dickman and Vidigal, J. Phys. A 35, 7269 (2002)], to obtain an expansion for stationary properties. Since the process has a strictly conserved particle density p, the Fourier mode N-1 k=0 p, when N , and so is not a random variable. Isolating this mode, we obtain a new effective action leading to an expansion for in the parameter 1/(1+4p). This requires enumeration and numerical evaluation of more than 200,000 diagrams, for which task we develop a computational algorithm. Predictions derived from this series are in good accord with simulation results. We also discuss the nature of correlation functions and one-site reduced distributions in the small- (high-density) limit. 相似文献
10.
Giuseppe Cilento Nelson Durán Klaus Zinner Carmen C. C. Vidigal Olga M. M. Faria Oliveira Marcela Haun Adelaide Fauoni Ohara Augusto Roberto Casadei de Baptista Etelvino J. H. Bechara 《Photochemistry and photobiology》1978,28(4-5):445-450
Abstract— Several hemeprotein-catalyzed reactions generate products of the type expected from the cleavage of a high energy intermediate. For some systems, the formation, in high yield, of a carbonyl compound in its excited triplet state has been firmly established on the basis of (i) equivalence of the chemiluminescence and phosphorescence spectra of the expected products; (ii) energy transfer to sensitizers containing heavy atoms and (iii) occurrence of photoproducts. The excited species appears to be generated within the enzyme and shielded from quenching by oxygen. It may be quenched, however, via long-range triplet-singlet energy transfer.
This work strongly supports our hypothesis that excited electronic states are also formed in biological systems which are not necessarily bioluminescent. One of the functions which peroxidases may thus fulfill might be the utilization of the potential of photochemistry in the absence of light. 相似文献
This work strongly supports our hypothesis that excited electronic states are also formed in biological systems which are not necessarily bioluminescent. One of the functions which peroxidases may thus fulfill might be the utilization of the potential of photochemistry in the absence of light. 相似文献
1