scholarly journals Molecular System Bioenergics of the Heart: Experimental Studies of Metabolic Compartmentation and Energy Fluxes versus Computer Modeling

2011 ◽  
Vol 12 (12) ◽  
pp. 9296-9331 ◽  
Author(s):  
Mayis Aliev ◽  
Rita Guzun ◽  
Minna Karu-Varikmaa ◽  
Tuuli Kaambre ◽  
Theo Wallimann ◽  
...  
Keyword(s):  
Computer Modeling ◽  
Molecular System ◽  
Experimental Studies ◽  
Energy Fluxes ◽  
Metabolic Compartmentation

scholarly journals A Parameterization Scheme for Air–Sea Surface Interface Fluxes: Design and Stand-Alone Experiments

2018 ◽  
Vol 75 (7) ◽  
pp. 2359-2383
Author(s):  
Haixiong Zhuang ◽  
Xiaojun Yang ◽  
Zhenling Wu
Keyword(s):  
Mixed Layer ◽  
Surface Wind ◽  
Experimental Studies ◽  
Ocean Surface ◽  
Atmospheric Modeling ◽  
Surface Interaction ◽  
Sea Surface ◽  
Bulk Temperature ◽  
Ocean Mixed Layer ◽  
Energy Fluxes

Abstract Observations show that sea surface temperature (SST) can vary up to several degrees in a day and sea surface energy fluxes up to a few hundreds of watts per square meter. For synoptic- and subsynoptic-scale atmospheric modeling, there remains a need for the parameterization of air–sea surface interaction using simple schemes. In this paper, such a simple scheme, Atmosphere–Ocean Surface Interaction Scheme (AOSIS), is presented so that the short time variations in SST and energy fluxes can be estimated using a small number of atmospheric and oceanic bulk quantities. The scheme consists of three components: a two-layer ocean temperature model, a wind-wave model, and a surface flux model. Numerical experiments show that the scheme performs well in simulating SST and the air–sea exchanges. Relative to other schemes, AOSIS shows the following improvements: 1) it simulates SST and the cool-skin and warm-layer effect of the ocean mixed layer without the input of ocean bulk temperature of the mixed layer as a prior condition, which is required by most one-layer models; 2) the depth of the ocean mixed layer is allowed to vary according to surface wind stress and buoyancy flux; and 3) a method for computing ocean surface roughness length is proposed, which accounts for the aerodynamic effect of wind-generated waves. For experimental studies, AOSIS can be used in stand-alone mode for the calculation of SST through a small number of bulk measurements. AOSIS can also be used as an interface between the atmosphere and ocean models to be coupled together.

scholarly journals Refining of high-phosphorus manganese alloys, which are formed during electrometallurgical Dephosphoration of manganese ore

2019 ◽  
pp. 43-53
Author(s):  
Myanovska Ya ◽  
Mishalkin A ◽  
Kamkina L ◽  
Du Yunsheng Du ◽  
Isaeva Lydmila ◽  
...  
Keyword(s):  
Computer Modeling ◽  
Experimental Studies ◽  
Refining Process ◽  
Manganese Ore ◽  
Manganese Alloy ◽  
The Real ◽  
Manganese Alloys ◽  
Real Process ◽  
Low Phosphorus ◽  
Kinetics Of

Goal. Creation of the most rational way of dephosphorization of manganese alloys. Method. Thermodynamic calculations to establish the preference of the reactions during dephosphorization. Computer modeling of the influence of the charge composition on the process of reducing the phosphorus content. Experimental studies in the laboratory during a two-stage processing of high phosphorus metal. Results. The results of computer modeling and experimental study of the refining process of manganese alloy with high content of silicon and phosphorus indicate the feasibility of using the experimental slag-forming mixture based on Na4SiO4. Comparisons of the calculated data with the results of experimental melting show that there are differences in their values. These differences are due to the fact that in real conditions the thermo-dynamic forecast does not always coincide with the kinetics of the real process. The obtained experimental data indicate that the analyzed system achieves a state of dynamic equilibrium in contrast to the data of thermodynamic calculations by the program, which does not take into account the kinetics of the real process and the assumptions made in the simulation. Scientific novelty. The results of experimental studies have shown that the adopted physico-chemical features of the one-stage method of refining the alloy from silicon and phosphorus at a temperature of ~ 1350oC, provide protection of manganese from oxidation with the use of Na4SiO4. Practical significance. Therefore, it is advisable to implement the developed scheme of dephosphorization of the accompanying manganese alloy, which is formed during the production of low phosphorus slag, in industrial conditions. Given that the limiting link in the refining process is the oxidation reaction of the phosphorus alloy due to the interaction with Fe2O3, it is advisable to use forced mixing of the metal and the alloy by purging with neutral gas. Key words: phosphorus, manganese ore, concomitant manganese alloy, low phosphorus slag, dephosphorization,

scholarly journals Insights into the cooperative nature of ATP hydrolysis in actin filaments

2018 ◽  
Author(s):  
Harshwardhan H. Katkar ◽  
Aram Davtyan ◽  
Aleksander E. P. Durumeric ◽  
Glen M. Hocky ◽  
Anthony C. Schramm ◽  
...  
Keyword(s):  
Actin Filament ◽  
Actin Filaments ◽  
Atp Hydrolysis ◽  
Molecular System ◽  
Experimental Studies ◽  
Monomer Concentration ◽  
Growth Dynamics ◽  
Coarse Grained ◽  
Subtle Change ◽  
Internal States

ABSTRACTActin filaments continually assemble and disassemble within a cell. Assembled filaments “age” as a bound nucleotide ATP within each actin subunit quickly hydrolyzes, followed by a slower release of the phosphate Pi, leaving behind a bound ADP. This subtle change in nucleotide state of actin subunits affects filament rigidity as well as its interactions with binding partners. We present here a systematic multiscale ultra-coarse-graining (UCG) approach that provides a computationally efficient way to simulate a long actin filament undergoing ATP hydrolysis and phosphate release reactions, while systematically taking into account available atomistic details. The slower conformational changes and their dependence on the chemical reactions are simulated with the UCG model by assigning internal states to the coarse-grained sites. Each state is represented by a unique potential surface of a local heterogeneous elastic network. Internal states undergo stochastic transitions that are coupled to conformations of the underlying molecular system. The UCG model reproduces mechanical properties of the filament and allows us to study whether fluctuations in actin subunits produce cooperative aging in the filament. Our model predicts that nucleotide state of neighboring subunit significantly modulates the reaction kinetics, implying cooperativity in ATP hydrolysis and Pi release. We further systematically coarse-grain the system into a Markov state model that incorporates assembly and disassembly, facilitating a direct comparison with previously published models. We find that cooperativity in ATP hydrolysis and Pi release significantly affects the filament growth dynamics only near the critical G-actin monomer concentration, while both cooperative and random mechanisms show similar growth dynamics far from the critical concentration. In contrast, filament composition in terms of the bound nucleotide distribution varies significantly at all monomer concentrations studied. These results provide new insights into the cooperative nature of ATP hydrolysis and Pi release and the implications it has for actin filament properties, providing novel predictions for future experimental studies.

scholarly journals EXPERIMENTAL STUDIES AND COMPUTER MODELING OF THE HOMESIS OF MICROORGANISMS BY IRRADIATION OF THE ELECTROMAGNETIC FIELD

2020 ◽  
pp. 109-114
Author(s):  
B. L. Ikhlov ◽  
◽  
I. L. Volkhin ◽  
A. Yu. Oshchepkov ◽  
◽  
...  
Keyword(s):  
Electromagnetic Field ◽  
Mycobacterium Tuberculosis ◽  
Computer Modeling ◽  
Experimental Studies ◽  
Torsional Vibrations ◽  
Resonant Frequencies ◽  
E Coli ◽  
Computer Research ◽  
Matlab Package ◽  
Number Of Bacteria

To show in experiments that hormesis is observed not only on E. coli, but also on other types of bacteria, investigate hormesis under influence of microwaves on Mycobacterium, suggest an explaination of this effect and develop a mathematical model for its computer research. M. avium 104 (subsp. hominissuis) and Mycobacterium tuberculosis strains were used, and electromagnetic field (EMF) irradiation was performed using an ultrahigh-frequency (UHF) generator at frequencies equal to the resonant frequencies of torsional vibrations of DNA of the bacteria used. Computer modeling was carried out in the MATLAB package on the basis of the modified Verhulst equation. Under the action of UHF EMF in cultures of M. avium 104 (subsp. hominissuis) and Mycobacterium tuberculosis on the first cell cycle, almost the same surges of survival were observed.: for a number of bacteria, the effect of microwave EMF, resonant natural frequency of torsional vibrations of their DNA, on the first division cycle hormesis is observed, which is explained by the stabilization of dying microorganisms, which is confirmed by computer simulation.

scholarly journals Development of a circular polarized fractal antenna

2019 ◽  
Vol 30 ◽  
pp. 05032
Author(s):  
Alexandr Savochkin ◽  
Alexander Nudga
Keyword(s):  
Experimental Study ◽  
Circular Polarization ◽  
Computer Modeling ◽  
Experimental Studies ◽  
Phase Shifts ◽  
Fractal Antenna ◽  
Delay Lines ◽  
Frequency Range ◽  
Flat Structure ◽  
Analytical Work

The article presents the results of analytical work, computer modeling, and experimental studies of the fractal antenna of circular polarization. The antenna is a flat structure parallel to the screen. The phase shifts necessary for the operation of the antenna are provided by delay lines. The antenna operates in the frequency range of 902 ... 928 MHz, an experimental study of its characteristics was performed in the same range.

scholarly journals Role of 2‒13C Isotopic Glyphosate Adsorption on Silver Nanoparticles Based on Ninhydrin Reaction: A Study Based on Surface—Enhanced Raman Spectroscopy

Nanomaterials ◽  
2020 ◽  
Vol 10 (12) ◽  
pp. 2539
Author(s):  
Meng-Lei Xu ◽  
Yu Gao ◽  
Jing Jin ◽  
Jin-Feng Xiong ◽  
Xiao Xia Han ◽  
...  
Keyword(s):  
Metal Surface ◽  
Density Functional ◽  
Molecular System ◽  
Raman Band ◽  
Experimental Studies ◽  
Surface Enhanced Raman Spectroscopy ◽  
Ag Nps ◽  
Surface Enhanced ◽  
Surface Enhanced Raman ◽  
Ninhydrin Reaction

Glyphosate is one of the most commonly used and non-selective herbicides in agriculture, which may directly pollute the environment and threaten human health. A simple and effective approach to its detection is thus quite necessary. Surface-enhanced Raman scattering (SERS) spectroscopy was shown to be a very effective method to approach the problem. However, sensitivity in SERS experiments is quite low, caused by different orientation/conformation of the adsorbed molecules on the metal surface, which limit its detection by using SERS. In this paper, 2‒13C‒glyphosate (hereafter: 13–GLP) was designed as a model molecule for theoretical and experimental studies of the molecule structure. Vibrational modes were assigned based on the modeling results obtained at the B3LYP/6-311++G** level by density functional theory (DFT) calculations, which were performed to predict the FT‒IR and Raman spectra. Band downshifts were caused by 13C atom isotopic substitution with mass changed. Moreover, SERS spectra of 13–GLP by combining ninhydrin reaction on Ag NPs were obtained. Isotopic Raman shifts are helpful in identifying the components of each Raman band through vibrations across the molecular system. They are coupled by probe molecules and thus bind to the substrates, indirectly offering the opportunity to promote interactions with Ag NPs and reduce the complex equilibrium between different orientation/conformation of glyphosate molecules on the metal surface.

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