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281.
Erfani Hamidreza Karadimitriou Nikolaos Nissan Alon Walczak Monika S. An Senyou Berkowitz Brian Niasar Vahid 《Transport in Porous Media》2021,140(1):421-435
Transport in Porous Media - Solute transport under single-phase flow conditions in porous micromodels was studied using high-resolution optical imaging. Experiments examined loading (injection of... 相似文献
282.
A number of studies performed on biological systems have shown that redox-active metals such as iron and copper as well as
other transition metals can undergo redox cycling reactions and produce reactive free radicals termed also reactive oxygen
species (ROS) or reactive nitrogen species (RNS). The most representative examples of ROS and RNS are the superoxide anion
radical and nitric oxide, respectively, both playing a dual role in biological systems. At low/moderate concentrations of
ROS and RNS, they can be involved in many physiological roles such as defense against infectious agents, involvement in a
number of cellular signaling pathways and other important biological processes. On the other hand, at high concentrations,
ROS and RNS can be important mediators of damage to biomolecules involving DNA, membrane lipids, and proteins. One of the
most damaging ROS occurring in biological systems is the hydroxyl radical formed via the decomposition of hydrogen peroxide
catalyzed by traces of iron, copper and other metals (the Fenton reaction). The hydroxyl radical is known to react with the
DNA molecule, forming 8-OH-Guanine adduct, which is a good biomarker of oxidative stress of an organism and a potential biomarker
of carcinogenesis. This review discusses the role of iron and copper in uncontrolled formation of ROS leading to various human
diseases such as cancer, cardiovascular disease, and neurological disorders (Alzheimer’s disease and Parkinson’s disease).
A discussion is devoted to the various protective antioxidant networks against the deleterious action of free radicals. Metal-chelation
therapy, which is a modern pharmacotherapy used to chelate redox-active metals and remove toxic metals from living systems
to avoid metal poisoning, is also discussed. 相似文献
283.
Two types of bifurcation diagrams of cytosolic calcium nonlinear oscillatory systems are presented in rectangular areas determined by two slowly varying parameters. Verification of the periodic dynamics in the two-parameter areas requires solving the underlying model a few hundred thousand or a few million times, depending on the assumed resolution of the desired diagrams (color bifurcation figures). One type of diagram shows period-n oscillations, that is, periodic oscillations having n maximum values in one period. The second type of diagram shows frequency distributions in the rectangular areas. Each of those types of diagrams gives different information regarding the analyzed autonomous systems and they complement each other. In some parts of the considered rectangular areas, the analyzed systems may exhibit non-periodic steady-state solutions, i.e., constant (equilibrium points), oscillatory chaotic or unstable solutions. The identification process distinguishes the later types from the former one (periodic). Our bifurcation diagrams complement other possible two-parameter diagrams one may create for the same autonomous systems, for example, the diagrams of Lyapunov exponents, diagrams for mixed-mode oscillations or the 0–1 test for chaos and sample entropy diagrams. Computing our two-parameter bifurcation diagrams in practice and determining the areas of periodicity is based on using an appropriate numerical solver of the underlying mathematical model (system of differential equations) with an adaptive (or constant) step-size of integration, using parallel computations. The case presented in this paper is illustrated by the diagrams for an autonomous dynamical model for cytosolic calcium oscillations, an interesting nonlinear model with three dynamical variables, sixteen parameters and various nonlinear terms of polynomial and rational types. The identified frequency of oscillations may increase or decrease a few hundred times within the assumed range of parameters, which is a rather unusual property. Such a dynamical model of cytosolic calcium oscillations, with mitochondria included, is an important model in which control of the basic functions of cells is achieved through the signal regulation. 相似文献
284.
285.
Jadwiga Walczak Izabella Rych owska-Himmel Elzbieta Mikos-Naw atyna 《Thermochimica Acta》1995,260(1-2):229-234
A diagram for the phase equilibria established in the two-component Fe2V4O13-WO3 system (one of the intersections of the Fe2O3-V2O5-WO3 three-component system) has been constructed based on the measurements made by DTA and X-ray phase analysis. The diagram shows that the system investigated does not appear to be a true two-component system, even below the solidus line. 相似文献
286.
Paper chromatography investigations were performed with the aim of tracing the adsorption mechanism of the selected higher fatty alcohols on a paper layer and determining the role of polar solvents in establishing thermodynamic equilibria. 相似文献
287.
This paper describes the rationale for carrying out EPR studies in human subjects in the clinical setting and the potential approaches and specific steps needed to make such studies feasible and useful. The suggested operational approach is to have the initial applications occur in as clinically useful and simple a manner as possible, with the expectation that once the technique is introduced and accepted in the clinical setting, that more complex and/or more technically difficult applications will be able to be developed. The initial approach should be based on EPR spectroscopy at 1.2 GHz focusing on clinical applications for which in vivo EPR provides a clearly useful approach to important clinical problems for which currently there is no good alternative approach, that can be carried out by measurements within 10 mm of the surface. The suggested initial clinical applications are: guiding tumor therapy for tumors and vascular disease by direct measurements of tissue pO2, characterizing and monitoring implanted drug delivery systems, and monitoring critical care. 相似文献
288.
M. C. Abreu T. Armstrong M. Baubillier W. Beusch A. Burns J. M. Gago A. Jacholkowski K. Knudson S. Otwinowski D. Perrin A. Palano M. Pimenta E. Quercigh Z. Strachman M. Szeptycka S. Tkaczyk R. Walczak R. Zitoun 《Zeitschrift für Physik A Hadrons and Nuclei》1986,324(1):1-8
Data on fast protons and antiprotons produced byπ ± incident on hydrogen and nuclear targets at 30 GeV/c are presented. The results covering the kinematic range 0.32 F <0.54 andp T >0.2 GeV/c, complete our previous paper. We give results on inclusive cross-sections as a function ofx F , ofp T 2 and on cross-section ratios. A search for effects of nuclear matter on the production of protons and antiprotons has yielded no major effects beyond final state absorption. 相似文献
289.
This article presents a selection of the relevant issues that emerge at the interface between chromatography and chemometrics. In the first part, we present advantages and drawbacks of applying signal-enhancement, warping and mixture-analysis methods. In the second part, we discuss typical examples of misuse and abuse of chemometrics that can occur with those less familiar with the data-processing approaches. Finally, we conclude that close collaboration between the communities of chromatographers and chemometricians will allow a deeper insight into the chromatographic systems being analyzed and permit new chromatographic problems to be solved in an efficient, elegant manner. 相似文献
290.
M. G. Abreu T. Armstrong M. Baubillier W. Beusch A. Burns N. Erschaidat J. Gago A. Jacholkowski K. Knudson S. Otwinowski D. Perrin A. Palano M. Pimenta E. Quercigh Z. Strachman M. Szeptycka S. Tkaczyk R. Walczak R. Zitoun 《Zeitschrift fur Physik C Particles and Fields》1984,25(2):115-120
We present the first results on the production of fast (p>10 GeV/c)p, \(\bar p\) , Λ and \(\bar \Lambda \) from π± hydrogen and nucleus interactions at 30 GeV/c using the CERN Ω′ spectrometer. We have used five nuclear targets (C, Al, Cu, Sn, Pb) to study theA-dependence of the inclusive particle distributions in the region 0.3<x F <0.6. The high statistical level of our experiment allows us to demonstrate the differentA-behaviour of baryon and antibaryon inclusive reactions. We relate this difference to the final state interaction inside a nucleus using the formation-zone model. 相似文献