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Superconductivity well above room temperature incompressed MgH6

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Frontiers of physics 2016年第6期11卷 103-107页

作者： R. Szczesniaki A. P. Durajski Institute of Physics Jan Dtugosz University Ave. Armii Krajowej 13/15 42-200 Czestochowa Poland Institute of Physics Czestoehowa University of Technology Ave. Arrnii Krajowej 19 42-200 Czestochowa Poland

It has been suggested that hydrogen-rich systems at high pressure may exhibit notably high super-conducting transition temperatures. One of the more interesting theoretical predictions was that hydrogen sulfide can be metallized and the high-temperature superconducting state can be induced. A record critical temperature (203 K) was later confirmed for H3S in an experiment. In this paper, we investigated, within the framework of the Eliashberg formalism, the properties of compressed MgH6, which is expected to be a very good candidate for room-temperature superconductivity. This applies particularly to the pressure range from 300 to 400 GPa, where the transition temperature is close to 400 K. Moreover, the estimated thermodynamic properties and the resulting dimensionless ratios exceed the predictions of the Bardeena€“Coopera€“Schrieffer theory. This behavior is attributed to the strong electrona€“phonon coupling and retardation effects existing in hydrogen-dominated materials under high pressure.

关键词： superconductors hydrogen-rich compounds high pressure thermodynamic properties 74.20.Fg 74.25.Bt 74.62.Fj

Microstructure and magnetic properties of Fe-Co-Nd-Y-B alloys obtained by suction casting method

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Journal of Rare Earths 2009年第4期27卷 680-683页

作者： J.Olszewski J.Zbroszczyk M.Hasiak J.Kaleta M.Nabiaek P.Bragiel K.Sobczyk W.Ciurzyńska J.wierczek A.Lukiewska Institute of Physics Cz■stochowa University of Technology Al.Armii Krajowej 19 42-200 Cz■stochowa Poland Institute of Materials Science and Applied Mechanics Wroctaw university of Technology ul.Smoluchowskiego 25 50-370 Wroctaw Poland jan dtugosz university Al.Armii Krajowej 13/15 42-200 Cz■stochowa Poland

The phase composition, magnetic properties i.e. coercivity and the magnetic polarization at room temperature for the bulk Fe67Co5Nd3Y6B19 and Fe64Co5Nd6Y6B19 alloys were studied. The bulk amorphous Fe67CosNd3Y6B19 alloy, inhomogeneous in the as-quenched state, crystallized after annealing at 948 K for 0.5 h and consisted of Nd2Fe14B-type, Fe2B and paramagnetic phases. The rapidly solidified Fe64Co5Nd6Y6B19 alloy contained the Nd2Fel4B-type and paramagnetic phases. The annealing of the bulk Fe67CosNd3Y6B19 alloy at 948 K for 0.5 h led to hard magnetic properties. However, the bulk Fe64Co5Nd6Y6B19 alloy exhibited good hard magnetic properties directly after preparation.

关键词： Moessbauer spectroscopy bulk alloys rare earth hard magnetic materials

Cerium dioxide as a new reactive sorbent for fast degradation of parathion methyl and some other organophosphates

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Journal of Rare Earths 2014年第4期32卷 360-370页

作者： Pavel janos Pavel Kuran Martin Kormunda Vaclav Stengl Tomas Matys Grygar Marek Dosek Martin Stastny Jakub Ederer Vera Pilarova Lubos Vrtoch Faculty of the Environment University of Jan Evangelista Purkyne Faculty of Science University of Jan Evangelista Purkyne Institute of Inorganic Chemistry AS CR v.v.i.

Cerium dioxide was used for the first time as reactive sorbent for the degradation of the organophosphate pesticides para-thion methyl, chlorpyrifos, dichlofenthion, fenchlorphos, and prothiofos, as well as of some chemical warfare agents-nerve gases soman and O-ethyl S-[2-（diisopropylamino） ethyl] methylphosphonothioate （VX）. CeO2 specimens were prepared by calcination of basic cerous carbonate obtained by precipitation from an aqueous solution. The CeO2 samples containing certain amounts （1 wt.%-5 wt.%） of the neighboring lanthanides （La, Pr, Nd） were prepared in a similar way from pure lanthanide salts. It was shown that ceria accelerated markedly the decomposition of parathion methyl causing the cleavage of the P-O-aryl bond in the pesticide molecule. A similar reaction mechanism was proposed for the degradation of other organophosphate pesticides and nerve agents. The degradation times （reaction half-times） were in an order of minutes in the presence of CeO2, compared to hours or days under common environ-mental conditions. The reaction in suitable organic solvents allowed conversions of about 90%for parathion methyl loading of 20 mg pesticide/g CeO2 within 2 h with a reactant half-life in the order of 0.1 min. The key parameter governing the degradation efficiency of CeO2 was the temperature during calcination. At optimum calcination temperature （about 773.15 K）, the produced ceria retained a sufficiently high surface area, and attained an optimum degree of crystallinity （related to a number of crystal defects, and thus poten-tial reactive sites）. The presence of other lanthanides somewhat decreased the reaction rate, but this effect was not detrimental and permitted the possible use of chemically impure ceria as a reactive sorbent. A fast organophosphate degradation was demonstrated not only in non-polar solvents （such as heptane）, but also in polar aprotic solvents （acetonitrile, acetone） that are miscible with water. This opens new possibilities for designi

关键词： cerium dioxide carbonate precursor lanthanides organophosphate pesticide parathion methyl chemical warfare agents hydrolysis non-aqueous solvents rare earths

The Numerical Comparison of Heat Transfer in a Coated and Fixed Bed of an Adsorption Chiller

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Journal of Thermal Science 2018年第5期27卷 421-426页

作者： GRABOWSKA Karolina SOSNOWSKI Marcin KRZYWANSKI Jaroslaw SZTEKLER Karol KALAWA Wojciech ZYLKA Anna NOWAK Wojciech Faculty of Mathematics and Natural Science Jan Dlugosz University Faculty of Energy and Fuels AGH University of Science and Technology

Ecological adsorption technology is becoming a focus of attention by industry due to the utilization of low grade thermal energy sources for cooling production. It can be a promising part of sustainable development concept of the global economy. Therefore, research aiming at improving their performance i.e. Coefficient of Performance(COP) by optimizing the construction of sorption beds with a built in heat exchanger system is crucial. The heat transfer characteristics between the bed of porous media(sorbent) and surface of the heat exchanger system determine the heating power of an adsorption chiller. The HP increase can be obtained by heat transfer intensification due to the increase in the thermal conductivity of the sorbent layer in the vicinity of the heat exchanger's surface. The novel modification of the sorbent layer structure is proposed in the paper in order to improve the heat transfer processes in the heat exchanger boundary layer. The analysis of desorption process conditions in the parametric model of a coated and fixed adsorption bed design is presented in the paper. The computational fluid dynamics(CFD) with conjugate heat transfer analysis is used to determine the crucial input parameters(temperature distribution in the sorbent bed) for further analytical calculations. The commercial code Ansys Fluent was used to perform numerical simulations. The developed computational model consisted of three subdomains representing heating water, heat exchanger material(copper) and sorbent(silica gel). The comparison of a novel coated design and a conventional fixed bed is discussed in the paper. The numerical analysis is based on experimental thermal conductivity measurements of the sorbent layer in different configurations, which were performed using Laser Flash Method.

关键词： adsorption chiller computational fluid dynamics low grade thermal energy sources coated adsorption bed silica gel thermal conductivity

An easy,convenient statistical method to analyze bark beetle populations

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Journal of Forestry Research 2023年第6期34卷 2027-2040页

作者： Andrzej Borkowski Department of Environmental Biology Institute of BiologyJan Kochanowski UniversityUniwersytecka 7 Str25-406 KielcePoland

A non-invasive method to estimate the number of Trypodendron lineatum holes on dead standing pines(Pinus sylvestris L.)was developed using linear and nonlinear estimations.A clas sical linear regres sion model was first used to analyze the relationship between the number of holes caused by *** on selected stem units and the total number of holes on an entire dead stem of ***,to obtain a better fit of the regression function to the data for the stem unit selected in the first step,piecewise linear regression(PLR)was ***,in an area used to evaluate wood decomposition(method validation),the total and mean numbers of *** holes were estimated for single dead trees and for a sample(n=8 dead trees).Data were collected in 2009(data set D1),in 2010-2014(data set D2)and in 2020(data set D3)in forests containing *** located within Suchedniow-Oblegorek Landscape Park,Poland.A model was constructed with three linear *** evaluation of model accuracy showed that it was highly effective regardless of the density of *** holes and sample *** method enables the evaluation of the biological role of this species in the decomposition of dead standing wood of *** in strictly protected areas.

关键词： Trypodendron lineatum Pinus sylvestris Population Wood decomposition Forest management Piecewise linear regression

Hylocomium splendens (Hedw.) *** Pleurozium schreberi (Brid.) *** trace element bioindicators:Statistical comparison of bioaccumulative properties

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Journal of Environmental Sciences 2013年第2期25卷 340-347页

作者： Sabina Doegowska Zdzisaw M.Migaszewski Artur Michalik Geochemistry and the Environment Division Institute of ChemistryJan Kochanowski University15GSwietokrzyska St25-406 KielcePoland

The principal objective of this study was to compare bioaccumulative properties of two terrestrial moss species Hylocomium splendens and Pleurozium schreberi from the Kielce area （south-central Poland）, using various statistical techniques. Forty-six moss samples from 23 sampling sites located within the city limits were analyzed for 33 trace elements. The results indicated that 17 elements （Ba, Ce, Co, Cu, Eu, Fe, Gd, Hg, La, Mo, Nd, Ni, Pb, Pr, Sm, V, Y） dominated in H. splendens, whereas only three elements （Mn, Sr, Zn） occurred in excessive amounts in P. schreberi. No differences in the distribution pattern of Dy, Er, Ho, Sn, Tb, Th and Yb were observed. The element concentration ratio （PI/Hy） varied from 0.50 to 1.19. For 14 elements （Ce, Co, Cu, Fe, Gd, Hg, La, Mo, Nd, Ni, Pb, Sm, Th, V）, PI/Hy 〈 1; for 4 elements （Cd, Mn, Sr, Zn）, PI/Hy 〉 1; for 7 elements （Ba, Dy, Er, Eu, Pr, Y, Yb）, PI/Hy = equalled 1. Czekanowski＇s method showed similarities in rare earth element concentrations for both moss species. The cluster analysis exhibited three significant clusters at D link /D max × 100 〈 50 for both moss species. Strong positive Spearman correlations between both moss species were recorded for the following pairs：Ba-Ba, Co-Co, Er-Er, Eu-Eu, Gd Gd, Mn-Mn, Ni-Ni, Pb-Pb, Pr-Pr, Sm-Sm, Th-Th, Y-Y, and Yb-Yb. Nonparametric tests （Sign test, Wilcoxon tests） showed statistically significant differences only for Cd, Ce, Co, Cu, Hg, Mo, Ni, Pb and Sr. The scanning electron microscope study of H. splendens and P. schreberi revealed a different morphology of these species with no injuries.

关键词： biomonitoring trace elements moss species accumulative properties comparison

Analysis of erosion rill development under rainfall events using structure-from-motion photogrammetry——a case study from Kielce(Holy Cross Mts.,Poland)

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Journal of Mountain Science 2022年第5期19卷 1231-1244页

作者： Piotr Tomasz KOPYSC jan Kochanowski university Institute of Geography and Environmental SciencesUniwersytecka 725-406 KielcePoland

The development of erosive landforms such as rills,ditches,slits,and gullies depends on many environmental factors;thus,the rate of the development of each individual form *** this paper,the author presents a case study of two erosion rills located on a hiking trails(Holy Cross Mts.)resulting after 2 years of monitoring in which the process of their evolution was precisely *** established,such landforms develop over time with variable rates and can represent multiple different ***,the final result of the rill development hardly reminds their original form and does not allow for interpretation of the events that affected it in the recent ***,the main objective was to determine the volumetric changes of erosion rills created by the surface runoff on both sections,during two years of *** objectives included a description of the physical and meteorological parameters,important in the development process and a comparison of them to the volumetric changes of each *** the Structure-from-motion(Sf M)photogrammetry technique,monitoring procedures have been performed quickly offering sufficient *** direct comparison,the digital elevation model of difference(Do D)method was used,enabling the calculation of *** results showed that the erosion to deposition ratio was more disproportionate during storm events or periods with higher depth of *** erosion to deposition balance for the entire monitoring period was negative and equal to 1448.84 kg or 410 Mg/ha for the first erosion rill and 1059.5 kg or 300 Mg/ha for the second *** erosion rills developed *** first erosion rill developed by linear cut into deeper and wider form,while the other,steeper rill,evolved from plunge pools merging together into deeper and wider form.

关键词： Erosion SfM DoD Rainfall Microtopography

Genotype 3-hepatitis C virus’last line of defense

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World Journal of Gastroenterology 2021年第11期27卷 1006-1021页

作者： Dorota Zarębska-Michaluk Department of Infectious Diseases Jan Kochanowski UniversityKielce 25-369ŚwiętokrzyskiePoland

Chronic infection with hepatitis C virus(HCV)is one of the leading causes of liver disease globally,affecting approximately 71 million *** majority of them are infected with genotype(GT)1 but infections with GT3 are second in *** many years,GT3 was considered to be less pathogenic compared to other GTs in the HCV family due to its favorable response to interferon(IFN)-based ***,the growing evidence of a higher rate of steatosis,more rapid progression of liver fibrosis,and lower efficacy of antiviral treatment compared to infection with other HCV GTs has changed this *** review presents the specifics of the course of GT3 infection and the development of therapeutic options for GT3-infected patients in the era of direct-acting antivirals(DAA).The way from a standard of care therapy with pegylated IFNalpha(pegIFNα)and ribavirin(RBV)through a triple combination of pegIFNα+RBV and DAA to the highly potent IFN-free pangenotypic DAA regimens is discussed along with some treatment options which appeared to be dead *** the implementation of highly effective pangenotypic regimens is the most recent stage of revolution in the treatment of GT3 infection,there is still room for improvement,especially in patients with liver cirrhosis and those who fail to respond to DAA therapies,particularly those containing inhibitors of HCV nonstructural protein 5A.

关键词： Hepatitis C virus Genotype 3 Antiviral treatment Interferon Direct-acting antivirals Pangenotypic

Ground settlement during tunneling in groundwater drawdown environment-Influencing factors

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Underground Space 2016年第1期1卷 20-29页

作者： Chungsik Yoo School of Civil Architectural Engineering and Landscape ArchitectureSungkyunkwan University2066 Seoboo RoJan-An GuSuwonKyong-Gi Do 16419Republic of Korea

In this paper,the results of a parametric study on groundwater drawdown-induced surface settlement during tunneling in waterbearing ground are presented.A calibrated stress–pore pressure coupled finite element model was adopted for the parametric *** results were analyzed to establish the relationships between key design issues,such as the ground surface settlement and groundwater drawdown,and influencing *** artificial neural network(ANN)-based sensitivity analysis was performed to obtain insight into the relative importance of the influencing *** results indicated that the primary influencing factors on the settlement development are the thickness and stiffness of the soil layer within the drawdown zone and the lining permeability,while the initial void ratio and the permeability of the soil layer were considered secondary influencing *** implications and findings of the study are discussed.

关键词： Conventional tunneling Ground settlement Groundwater Finite element method Stress-pore pressure coupled analysis