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81.
Yuri A. de Oliveira Só Mônica de Abreu Silva Fernando M. Carvalho Alessandra S. Kiametis Ricardo Gargano 《International journal of quantum chemistry》2020,120(11):e26194
Oxidative stress is an imbalance between the production of free radicals and the antioxidant defenses of the organism. Heart diseases, anemia, inflammation, and neurodegenerative disorders have been associated with this biological condition. Trolox is a notable antioxidant drug similar to vitamin E, and it is used to decrease the oxidative stress or repair the damage caused by it. In this work, the virtual screening technique is applied to identify compounds with antioxidant activities similar to Trolox. The antioxidant activity of these compounds was assessments by the mechanisms of hydrogen atom transfer and single electron transfer. Properties such as bond dissociation enthalpy, adiabatic ionization potential, Gibbs free reaction energy, spin density, highest occupied molecular orbital (HOMO), and GAP (HOMO-LUMO) energies, obtained from the DFT approach, point out to the predominance of the HAT mechanism for the antioxidant action of these compounds. The obtained results contribute to a better understanding of the chemical and physical properties responsible for antioxidant activity and the design of new antioxidant agents. 相似文献
82.
83.
Vivian?Regina?Trist?o Fernando?Felippe?de?Carvalho Cinthia?Zanini?Gomes Adriana?Regina?Miranda Cíntia?C.?Vequi-Suplicy Maria?Teresa?Lamy Nestor?Schor Maria?Helena?Bellini 《Journal of fluorescence》2010,20(3):665-669
The progression to end-stage renal failure is independent of the initial pathogenic mechanism. Metabolic acidosis is a common
consequence of chronic renal failure that results from inadequate ammonium excretion and decreased tubular bicarbonate reabsorption.
Protoporphyrin IX (PpIX) is the immediate metabolic precursor of the heme molecule. The purpose of this study was to evaluate
the levels of erythrocytes protoporphyrin IX at an animal model during progressive renal disease. A total of 36 eight-week-old
male Wistar rats were divided into six groups: Normal, 4 and 8 weeks after 5/6 nephrectomy (NX). Renal function was evaluated
by creatinine clearance and plasma creatinine levels. The autofluorescence of erythrocytes porphyrin of healthy and NX rats
was analyzed using fluorescence spectroscopy. Emission spectra were obtained by exciting the samples at 405 nm. Significant
differences between normal and NX rats autofluorescence shape occurred in the 600–700 nm spectral region. A correlation was
observed between emission band intensity at 635 nm and progression of renal disease. 相似文献
84.
85.
Valencia L Martinez J Macías A Bastida R Carvalho RA Geraldes CF 《Inorganic chemistry》2002,41(20):5300-5312
Complexes between the Py(2)N(6)Ac(4) (H(4)L) ligand containing four carboxylate pendant arms and trivalent lanthanide ions have been synthesized, and structural studies have been made both in the solid state and aqueous solution. The crystal structures of the La, Ce, Sm, Tb, Dy, Ho, Er, Tm, and Lu complexes, with chemical formulas [LaH(2)L](NO(3)).3H(2)O (1), [Ce(4)L(2)](NO(3))(4).30H(2)O (2), [SmHL].EtOH.3H(2)O (5), [TbHL].EtOH.3H(2)O (8), [DyHL].2EtOH.2H(2)O (9), [HoHL].3H(2)O (10), [ErHL].EtOH.3H(2)O (11) [TmHL].EtOH.3H(2)O (12), and [LuHL].3H(2)O (14), have been determined by single-crystal X-ray crystallography. In the solid state, the complexes of the lighter lanthanide ions La(3+)-Dy(3+) show a 10-coordinated geometry close to a distorted bicapped antiprism, where the carboxylate pendants are situated alternatively above and below the best plane that contains the nitrogen donor atoms. The complexes of the heavier ions, Ho(3+)-Lu(3+), have a 9-coordinated geometry close to distorted tricapped trigonal prism, with one of the pendant carboxylate groups uncoordinated. The ligand is in a "twist-fold" conformation, where the twisting of the pyridine units is accompanied by an overall folding of the major ring of the macrocycle so that the pyridine nitrogen atoms and the metal are far from linear. The aqueous solution structures of the complexes were thoroughly characterized, the diamagnetic ones (La(3+) and Lu(3+)) by their COSY NMR spectra, and the paramagnetic complexes using a linear least-squares fitting of the (1)H LIS (lanthanide-induced shift) and LIR (lanthanide-induced relaxation) data with rhombic magnetic susceptibility tensors. The solution structures obtained for the La(3+)-Dy(3+) complexes (10-coordinate) and for the Tm(3+)-Lu(3+) complexes (9-coordinate) are in very good agreement with the corresponding crystal structures. However, the 10-coordinate structure is still exclusive in solution for the Ho(3+) complex and predominant for the Er(3+) complex. 相似文献
86.
A method for the determination of 3-chloro-4-(dichloromethyl)-5-hydroxy-2[5H]-furanone (MX), in drinking water by GC-MS with a limit of detection of 3.0 microg/l and a limit of quantification of 7.0 microg/l is presented. Clean-up by SPE and extraction of water samples with dichloromethane were carried out before the preconcentration of MX, which was derivatized directly in the injector of the GC, and the MX trimethylsilyl derivative was identified and quantitatively determined by MS. 相似文献
87.
Knowledge of the element content of biological systems is important in enabling understanding of uptake mechanisms and physiological response to stress conditions. In this work concentrations of mineral elements in sycamore (Acer pseudoplatanus L.) cells grown in the presence of cadmium have been analysed and compared with concentrations in control cells. Energy-dispersive X-ray fluorescence (EDXRF) was used to quantify the nutrients K, Ca, Mn, Fe, Cu, and Zn present in the cells. The reproducibility and accuracy of the technique were demonstrated by analysis of biological reference materials. Exposure of sycamore cells to cadmium had induced variation in the content of some elements. Mn, Cu, Zn, and, particularly, Fe concentrations in cells exposed to Cd were higher than those found in control cells. Ca is adsorbed on the cell walls and the concentration of K is not affected by the presence of Cd. 相似文献
88.
This is the first of two papers devoted to the study of a nonlocal evolution equation that describes the evolution of the local magnetization in a continuum limit of an Ising spin system with Kawasaki dynamics and Kac potentials. We consider subcritical temperatures, for which there are two local equilibria, and begin the proof of a local nonlinear stability result for the minimum free energy profiles for the magnetization at the interface between regions of these two different local equilibria; i.e., the fronts. We shall show in the second paper that an initial perturbation v
0 of a front that is sufficiently small in L
2 norm, and sufficiently localized that x
2
v
0(x)2
dx<, yields a solution that relaxes to another front, selected by a conservation law, in the L
1 norm at an algebraic rate that we explicitly estimate. There we also obtain rates for the relaxation in the L
2 norm and the rate of decrease of the excess free energy. Here we prove a number of estimates essential for this result. Moreover, the estimates proved here suffice to establish the main result in an important special case.on leave from 相似文献
89.
Carlos A. Aragão de Carvalho 《Nuclear Physics B》1977,119(3):401-412
We investigate a theory using Callan-Symanzik equations. Logarithmic corrections to trivial fixed-point behaviour are obtained. The theory is shown to correspond to a model for tri-critical phenomena in 3He4He mixtures. 相似文献
90.
Dominating proton structure has been identified in the Kπ=3+ band of 168Yb, contrasting with neutron structure in the corresponding band of 172Yb. A region of low-lying Kπ=3+ bands is now established, with N=98?104, Z=68?72. For all stable nuclei in this region, the IπK=4+3 state is excited by inelastic deutron scattering. 相似文献