The document discusses enhancing the working temperature span and refrigerant capacity of two-phase composite systems based on amorphous FeZrBCu ribbons. It first introduces the magnetocaloric effect and improving the relative cooling power through composite compounds. It then presents results on the magnetocaloric properties of FeZrBCu amorphous alloys, including their tunable Curie temperatures and large magnetic entropy changes. The advantages of using these alloys in two-phase composite systems are discussed.
Kirkwood-Buff Theory of Solutions and the Development of Atomistic and Coarse...Nikos Bentenitis
This document discusses the development of atomistic and coarse-grained force fields using the Kirkwood-Buff theory of solutions.
The Kirkwood-Buff theory relates the structure of solutions to their thermodynamic properties through integrals known as Kirkwood-Buff integrals. Several force fields have been developed that reproduce experimental Kirkwood-Buff integrals through adjustments to effective charges. Coarse-grained force fields can also be developed using this approach by mapping molecules to beads and deriving potentials of mean force. The document outlines methods for developing a coarse-grained force field for an ionic liquid in water based on iterative Boltzmann inversion and potential of mean force calculations from all-atom simulations.
Phase Equilibrium Of Structure Ii Clathratesshaunakpotdar
The document provides an overview of gas hydrates including their structure, applications, phase equilibrium modeling, and molecular dynamic simulations. Gas hydrates are crystalline structures formed when gas molecules like methane are trapped within a lattice of water molecules. They are stable under conditions of low temperature and high pressure. The document discusses gas hydrate structures, applications in energy storage and transport, modeling of phase equilibria, and results from molecular dynamic simulations validating distortion models of gas hydrate properties.
Heat Capacity of BN and GaN binary semiconductor under high Pressure-Temperat...IOSR Journals
In this paper, we have calculated the molar heat capacity for cubic zinc blende (cZB) BN and GaN binary semiconductors at high pressure-temperature (PT). For the calculation of heat capacity, we firstly obtained the Debye temperature (ϴD) variation with temperature and at higher temperature it becomes constant with temperature in quasi-harmonic approximation limits. We have also calculated the static Debye temperature (ϴD) from elastic constant for the both BN and GaN binary semiconductors. The elastic constants are calculated from the energy-strain relation using plane wave method in DFT approach. All the calculated results are well consistence with experimental and reported data
Magnetic entropy change and critical exponentsMary Oliveira
1) The document analyzes the magnetic entropy change and critical exponents in the double perovskite material Y2NiMnO6, which exhibits a second-order ferromagnetic to paramagnetic transition at 86 K.
2) A maximum magnetic entropy change of -6.57 J/kg-K was measured for a field change of 80 kOe. Critical exponents were obtained from analysis of the spontaneous magnetization and inverse susceptibility, and were found to be consistent with 3D Heisenberg behavior.
3) Rietveld refinement of the crystal structure confirmed the material crystallizes in a monoclinic structure with alternating Ni2+ and Mn4+ ions along the c-axis and tilted oct
11.a new mechanism of sodium zirconate formationAlexander Decker
This document presents a new mechanism for forming sodium zirconate (Na2ZrO3) through the thermal decomposition of sodium acetate (CH3COONa) and zirconium(IV) acetylacetonate (Zr(C5H7O2)4). Thermogravimetric analysis showed the reaction occurs in three significant weight losses. Fourier transform infrared spectroscopy identified gases like CO2 and CO released during the reaction. X-ray diffraction confirmed the product was sodium zirconate. A kinetic study determined the activation energy, pre-exponential factor, and reaction order for each weight loss region using the Arrhenius equation. The proposed mechanism involves three reactions corresponding to the decomposition
This document summarizes a talk on the variation of fundamental constants over time. It discusses several methods for measuring potential variations, including analyses of the cosmic microwave background, quasar absorption spectra, radioactive decay rates from the natural nuclear reactor at Oklo, and comparisons of atomic clock rates. Measurements from big bang nucleosynthesis and quasar data suggest the fine structure constant may have been smaller in the early universe, varying on the order of 10^-15 per year. However, results are not conclusive and depend on theoretical models. Ongoing work using improved atomic clocks aims to more precisely measure any drift of fundamental constants like the fine structure constant and quark-mass ratios over time.
The document discusses various types of phase transformations in solids, including diffusional and diffusionless transformations. It focuses on diffusional transformations involving long-range and short-range diffusion, such as precipitation reactions where a supersaturated solid solution transforms into a more stable solid solution phase and a precipitate phase. Precipitation can occur through homogeneous or heterogeneous nucleation of the precipitate phase, and factors such as the driving force for precipitation, interfacial energy, and undercooling determine the rate of nucleation and growth.
Kirkwood-Buff Theory of Solutions and the Development of Atomistic and Coarse...Nikos Bentenitis
This document discusses the development of atomistic and coarse-grained force fields using the Kirkwood-Buff theory of solutions.
The Kirkwood-Buff theory relates the structure of solutions to their thermodynamic properties through integrals known as Kirkwood-Buff integrals. Several force fields have been developed that reproduce experimental Kirkwood-Buff integrals through adjustments to effective charges. Coarse-grained force fields can also be developed using this approach by mapping molecules to beads and deriving potentials of mean force. The document outlines methods for developing a coarse-grained force field for an ionic liquid in water based on iterative Boltzmann inversion and potential of mean force calculations from all-atom simulations.
Phase Equilibrium Of Structure Ii Clathratesshaunakpotdar
The document provides an overview of gas hydrates including their structure, applications, phase equilibrium modeling, and molecular dynamic simulations. Gas hydrates are crystalline structures formed when gas molecules like methane are trapped within a lattice of water molecules. They are stable under conditions of low temperature and high pressure. The document discusses gas hydrate structures, applications in energy storage and transport, modeling of phase equilibria, and results from molecular dynamic simulations validating distortion models of gas hydrate properties.
Heat Capacity of BN and GaN binary semiconductor under high Pressure-Temperat...IOSR Journals
In this paper, we have calculated the molar heat capacity for cubic zinc blende (cZB) BN and GaN binary semiconductors at high pressure-temperature (PT). For the calculation of heat capacity, we firstly obtained the Debye temperature (ϴD) variation with temperature and at higher temperature it becomes constant with temperature in quasi-harmonic approximation limits. We have also calculated the static Debye temperature (ϴD) from elastic constant for the both BN and GaN binary semiconductors. The elastic constants are calculated from the energy-strain relation using plane wave method in DFT approach. All the calculated results are well consistence with experimental and reported data
Magnetic entropy change and critical exponentsMary Oliveira
1) The document analyzes the magnetic entropy change and critical exponents in the double perovskite material Y2NiMnO6, which exhibits a second-order ferromagnetic to paramagnetic transition at 86 K.
2) A maximum magnetic entropy change of -6.57 J/kg-K was measured for a field change of 80 kOe. Critical exponents were obtained from analysis of the spontaneous magnetization and inverse susceptibility, and were found to be consistent with 3D Heisenberg behavior.
3) Rietveld refinement of the crystal structure confirmed the material crystallizes in a monoclinic structure with alternating Ni2+ and Mn4+ ions along the c-axis and tilted oct
11.a new mechanism of sodium zirconate formationAlexander Decker
This document presents a new mechanism for forming sodium zirconate (Na2ZrO3) through the thermal decomposition of sodium acetate (CH3COONa) and zirconium(IV) acetylacetonate (Zr(C5H7O2)4). Thermogravimetric analysis showed the reaction occurs in three significant weight losses. Fourier transform infrared spectroscopy identified gases like CO2 and CO released during the reaction. X-ray diffraction confirmed the product was sodium zirconate. A kinetic study determined the activation energy, pre-exponential factor, and reaction order for each weight loss region using the Arrhenius equation. The proposed mechanism involves three reactions corresponding to the decomposition
This document summarizes a talk on the variation of fundamental constants over time. It discusses several methods for measuring potential variations, including analyses of the cosmic microwave background, quasar absorption spectra, radioactive decay rates from the natural nuclear reactor at Oklo, and comparisons of atomic clock rates. Measurements from big bang nucleosynthesis and quasar data suggest the fine structure constant may have been smaller in the early universe, varying on the order of 10^-15 per year. However, results are not conclusive and depend on theoretical models. Ongoing work using improved atomic clocks aims to more precisely measure any drift of fundamental constants like the fine structure constant and quark-mass ratios over time.
The document discusses various types of phase transformations in solids, including diffusional and diffusionless transformations. It focuses on diffusional transformations involving long-range and short-range diffusion, such as precipitation reactions where a supersaturated solid solution transforms into a more stable solid solution phase and a precipitate phase. Precipitation can occur through homogeneous or heterogeneous nucleation of the precipitate phase, and factors such as the driving force for precipitation, interfacial energy, and undercooling determine the rate of nucleation and growth.
The FTIR and FT Raman spectra of 1-4-Dichloro-2-NitroBenzene (14DC2NB) have been recorded in the region 4000-400 cm-1 and 3500-50 cm-1 respectively. The optimized geometry ,frequency and intensity of the vibrational bands of 1-4-Dichloro-2-NitroBenzene (14DC2NB) was obtained by the Density functional theory (DFT)using the basis set 6-31g(d,p). The harmonic vibrational frequencies were calculated and scaled values have been compared with experimental FT-IR and FT-Raman spectra. The Calculated and Observed frequencies are found to be in good agreement. UV-Visible spectrum of the compound was recorded, the electronic properties and HOMO - LUMO energies were calculated by Time Dependent DFT (TD-DFT) approach. A detailed interpretation of the infrared and Raman spectra were also reported based on Potential Energy Distribution (PED). The 1H and 13C nuclear magnetic resonance (NMR) chemical shifts of 14DC2NB were calculated using the GIAO approach by applying B3LYP method. The calculated HOMO and LUMO energies show that charge transfer occurs within the molecule. The Chemical reactivity and Thermodynamic properties of 14DC2NB at different temperatures were also calculated
Apartes de la Conferencia de la SJG del 14 y 21 de Enero de 2012Nonlinear ele...SOCIEDAD JULIO GARAVITO
This document summarizes a research article about nonlinear electrodynamics and its effects on the polarization of the cosmic microwave background radiation. It introduces nonlinear electrodynamics models as alternatives to Maxwell's electrodynamics. The document then discusses how nonlinear electrodynamics is minimally coupled to gravity and derives the relevant equations of motion. It focuses on analyzing the Pagels-Tomboulis nonlinear electrodynamics Lagrangian and computing the polarization angle of photons propagating in an expanding universe with planar symmetry. Constraints on the nonlinear electrodynamics parameter are obtained using data on cosmic magnetic field strengths and the rotation of CMB polarization spectra measured by experiments.
The document discusses heat transfer and thermal properties of materials.
[1] It explains thermal capacity as the amount of thermal energy needed to raise the temperature of a material by 1 degree. Thermal expansion is caused by the asymmetric nature of the interatomic potential energy curve, causing the average atomic separation to increase with temperature. Thermal conductivity involves the transfer of kinetic energy between energetic conduction electrons and vibrating atoms.
[2] It provides equations for linear and volumetric thermal expansion coefficients. The thermal expansion coefficient of metals generally increases with decreasing melting point.
[3] Thermal conductivity in metals occurs via conduction electrons, while in nonmetals it occurs via phonon vibrations
High pressure structural properties of rare earth antimonideAlexander Decker
1) The document investigates the high-pressure structural phase transition of rare-earth antimonide DySb using a three-body potential model with electronic polarizability.
2) This model predicts a first-order phase transition from the NaCl (B1) structure to the CsCl (B2) structure in DySb at 22.6 GPa, with a 3.8% volume collapse.
3) The predicted transition pressure and volume change are in good agreement with available experimental data.
Study on rare-earth–doped type-I germanium clathratesYang Li
The synthesis of rare-earth clathrates RExBa8xGa16Ge30 is a challenging task. The Group IV clathrates with rare-earth doping are hardly to be experimentally prepared, except Eu clathrate. In the current study, the first-principle method based on the density functional theory was implemented. The effects of the various RE elements doping on the binding energy and chemical reaction drive energy were studied by optimizing the phase structure. The energy calculations suggest that it is difficult to synthesize RE clathrates without Ga doping. The function of Ga doping is to effectively increase the drive chemical reaction in order to synthesize the clathrates. The simulation shows that, besides Eu, other rare-earth elements, such as Sm, Nd, and Yb can also enter cage lattice in the considering of drive energy, thus making it possible to synthesize the (RE,Ba)8Ge30Ga16 clathrates.
Research Inventy : International Journal of Engineering and Scienceresearchinventy
This document summarizes a research study on the thermoluminescence properties of nanocrystalline europium-doped barium sulfate (BaSO4:Eu) phosphor. Key findings include:
1) Nanocrystalline BaSO4:Eu powder was successfully synthesized via a chemical co-precipitation technique and characterized using XRD and TEM analysis.
2) TL measurements showed a single prominent dosimetric peak around 456 K, above room temperature, making the material suitable for radiation dosimetry.
3) The material exhibited a linear dose response up to 100 Gy. Deconvolution of the TL glow curve identified two trap centers responsible for the observed luminescence
Fluorescence quenching of 5-methyl-2-phenylindole (MPI) by carbon tetrachlori...IOSR Journals
The fluorescence quenching of 5-methyl-2-phenylindole (MPI) by carbon tetrachloride by steady state in different solvents, and by transient method in benzene has been carried out at room temperature. The Stern–Volmer (SV) plot has been found to be non-linear with a positive deviation for all the solvents studied. In order to interpret these results we have invoked the ground state complex and sphere of action static quenching models. Using these models various rate parameters have been determined. The magnitudes of these parameters imply that sphere of action static quenching model agrees well with the experimental results. Hence the positive deviation in the SV plots is attributed to the static and dynamic quenching. Further, from the studies of temperature dependence of rate parameters and lifetime measurements, it could be explained that the positive deviation is due to the presence of a small static quenching component in the overall dynamic quenching. With the use of finite sink approximation model, it was possible to check whether these bimolecular reactions as diffusion limited and to estimate independently distance parameter R′ and mutual diffusion coefficient D. Finally an effort has been made to correlate the values of R′ and D with the values of the encounter distance R and the mutual diffusion coefficient D determined using the Edward's empirical relation and Stokes–Einstein relation.
This study examines the clustering properties and redshift evolution of bias for 593 X-ray selected AGN from the XMM-Newton survey in the COSMOS field with spectroscopic redshifts below z=4. The authors find evidence that the bias factor increases with redshift for the total AGN population, from b=2.30 at z=0.92 to b=4.37 at z=1.94. Splitting the sample, they observe a similar increase in bias with redshift for broad-line and unobscured AGN, corresponding to a constant halo mass of logM~13.28 and logM~13, respectively. The observed bias factors cannot be reproduced by models assuming AGN are triggered
SIMULATION OF GENERATION OF HIGH PRESSURE AND TEMPERATURE IN METALS UNDER SHO...IJORCS
This document simulates the generation of high pressure and temperature in metals under shock loading. It presents equations to model the total pressure and energy behind a shock front in metals. The pressure is modeled as a function of density ratio and temperature, taking into account cold, thermal, and excitation pressures. Results show that as the shock wave converges towards the center of a spherical metal sample, excitation pressure dominates over elastic and thermal pressures. Graphs show the variation of pressure and temperature in different metals like aluminum, iron, stainless steel, molybdenum, and iridium as the shock wave moves inward. Thermal pressure initially increases then levels off, while excitation pressure rises very fast before decreasing as the shock nears the center
First principles study of electronic, elastic and thermal properties of b2 ty...Alexander Decker
This document reports on a first principles study of the electronic, elastic, and thermal properties of RECd (RE = La, Ce, and Pr) intermetallic compounds using density functional theory. The compounds were found to be metallic in nature. Elastic constants were calculated and satisfied mechanical stability criteria, though values have not been experimentally measured. Among the compounds, PrCd was predicted to be most ductile based on its bulk to shear modulus ratio. Thermal properties like Debye temperature were also derived from the calculated elastic constants. This study provides the first theoretical predictions of elastic properties of these RECd intermetallic compounds.
This document discusses the hydrodynamic equations that describe neutral gas and plasma, and how they are modified to become the magnetohydrodynamic (MHD) equations when a conducting fluid is in a magnetic field. It introduces the continuity, momentum, and entropy equations for neutral gas hydrodynamics. It then explains how these are updated to the MHD equations by adding magnetic forces and Ohm's law relating current and fields. The key MHD equations derived include equations for momentum, entropy, and the magnetic field evolving due to motion and diffusion.
Electronic structure of strongly correlated materials Part II V.AnisimovABDERRAHMANE REGGAD
This document summarizes applications of the LDA+U and LDA+DMFT methods to strongly correlated materials. It discusses how these methods can accurately model Mott insulators, charge order, spin order, orbital order, and other phenomena. Specific examples discussed include charge ordering in Fe3O4, orbital ordering in KCuF3 and LaMnO3, and the spin state of Co3+ in LaCoO3. It also outlines the theoretical foundations and computational schemes of the LDA+U and LDA+DMFT methods, such as how the quantum Monte Carlo method can be used to solve the effective impurity problem in LDA+DMFT.
Dielectric Relaxation And Molecular Interaction Studies Of PEG With Non-Polar...IOSR Journals
This document discusses a study of the dielectric relaxation and molecular interactions of polyethylene glycol (PEG) with non-polar solvents like carbon tetrachloride, benzene, and 1,4-dioxane using time domain reflectometry technique. The complex dielectric permittivity was measured for PEG-solvent mixtures at different concentrations from 10 MHz to 30 GHz. Parameters like the static dielectric constant, relaxation time, Bruggeman factor, and Kirkwood correlation factors were determined. The results indicate that heteromolecular hydrogen bonding between PEG and the solvents significantly affects the dielectric properties of the mixtures.
Quantum-Gravity Thermodynamics, Incorporating the Theory of Exactly Soluble Active Stochastic Processes, with Applications
by Daley, K.
Published in IJTP in 2009. http://adsabs.harvard.edu/abs/2009IJTP..tmp...67D
W. Buchmüller: Cosmological B-L Breaking: Baryon Asymmetry, Dark Matter and G...SEENET-MTP
1) Cosmological B−L breaking can provide a unified explanation for inflation, baryogenesis via leptogenesis, and dark matter in the form of gravitinos or higgsinos/winos. Spontaneous breaking of B−L symmetry at high scales generates heavy neutrino masses and can drive hybrid inflation.
2) Decay of the false vacuum after hybrid inflation reheats the universe and produces an initial population of particles. Boltzmann equations track the evolution and show this process can successfully generate the observed baryon asymmetry via leptogenesis and dark matter density in gravitinos.
3) Relic gravitational waves provide a potential test, with contributions predicted from inflation, preheating after inflation ends, and cosmic
Nucleation III: Phase-field crystal modeling of nucleation processPFHub PFHub
The document summarizes research on modeling nucleation processes using phase-field crystal modeling. It discusses how phase-field crystal models can capture nucleation and growth phenomena observed in experiments and atomistic simulations. Specifically, it describes how different phase-field crystal models are able to simulate:
1) Homogeneous and heterogeneous nucleation processes in 2D and 3D, including the effects of lattice mismatch and particle-induced nucleation.
2) Continuous cooling simulations that show amorphous phase formation prior to crystallization, similar to experimental observations in colloids.
3) Instantaneous quenching simulations that produce amorphous clusters and domains that facilitate heterogeneous nucleation of body-centered cubic crystals.
4
This document summarizes a molecular dynamics study of the stacking interactions between nucleobase pairs in dinucleoside monophosphates in aqueous solution. 32 dinucleoside monophosphates containing adenine, thymine, cytosine and guanine were simulated for 40 nanoseconds. A reaction coordinate was defined to quantify stacked and unstacked states based on the distance and angle between nucleobase planes. Free energies were calculated for all base pair combinations, with AG stacking being most favorable and TT/CC stacking least favorable. The presence of a 2'-OH group in RNA dinucleosides increased stacking but decreased compactness relative to DNA. Base dipole orientations in stacked states were also analyzed.
This lecture covered enzymatic catalysis and enzyme kinetics. It discussed how enzymes speed up reactions by lowering the activation energy and transition state through substrate binding and use of catalytic groups. It also described Michaelis-Menten enzyme kinetics and different inhibition mechanisms like competitive and noncompetitive inhibition. Single-molecule studies reveal enzymes have dynamic conformations that result in a distribution of catalytic activities.
Sainsbury's plans to redevelop its regional distribution depot in Basingstoke to provide a modern, more efficient facility. The existing 300,000 sq ft depot built in 1964 is outdated and at full capacity. The proposed redevelopment will increase distribution efficiency, secure Sainsbury's long-term future in Basingstoke, and safeguard existing jobs. Construction of the new 15-hectare site will begin in November 2011 if planning approval is granted.
The Houston retail market posted positive net absorption of 397,000 square feet in Q1 2013, with vacancy declining slightly to 7.0%. Rental rates increased to an average of $14.68 per square foot. New retail space under construction totaled 585,000 square feet. The Houston job market and economy remained strong, with 118,700 new jobs added in the last year and unemployment falling to 6.3%.
The FTIR and FT Raman spectra of 1-4-Dichloro-2-NitroBenzene (14DC2NB) have been recorded in the region 4000-400 cm-1 and 3500-50 cm-1 respectively. The optimized geometry ,frequency and intensity of the vibrational bands of 1-4-Dichloro-2-NitroBenzene (14DC2NB) was obtained by the Density functional theory (DFT)using the basis set 6-31g(d,p). The harmonic vibrational frequencies were calculated and scaled values have been compared with experimental FT-IR and FT-Raman spectra. The Calculated and Observed frequencies are found to be in good agreement. UV-Visible spectrum of the compound was recorded, the electronic properties and HOMO - LUMO energies were calculated by Time Dependent DFT (TD-DFT) approach. A detailed interpretation of the infrared and Raman spectra were also reported based on Potential Energy Distribution (PED). The 1H and 13C nuclear magnetic resonance (NMR) chemical shifts of 14DC2NB were calculated using the GIAO approach by applying B3LYP method. The calculated HOMO and LUMO energies show that charge transfer occurs within the molecule. The Chemical reactivity and Thermodynamic properties of 14DC2NB at different temperatures were also calculated
Apartes de la Conferencia de la SJG del 14 y 21 de Enero de 2012Nonlinear ele...SOCIEDAD JULIO GARAVITO
This document summarizes a research article about nonlinear electrodynamics and its effects on the polarization of the cosmic microwave background radiation. It introduces nonlinear electrodynamics models as alternatives to Maxwell's electrodynamics. The document then discusses how nonlinear electrodynamics is minimally coupled to gravity and derives the relevant equations of motion. It focuses on analyzing the Pagels-Tomboulis nonlinear electrodynamics Lagrangian and computing the polarization angle of photons propagating in an expanding universe with planar symmetry. Constraints on the nonlinear electrodynamics parameter are obtained using data on cosmic magnetic field strengths and the rotation of CMB polarization spectra measured by experiments.
The document discusses heat transfer and thermal properties of materials.
[1] It explains thermal capacity as the amount of thermal energy needed to raise the temperature of a material by 1 degree. Thermal expansion is caused by the asymmetric nature of the interatomic potential energy curve, causing the average atomic separation to increase with temperature. Thermal conductivity involves the transfer of kinetic energy between energetic conduction electrons and vibrating atoms.
[2] It provides equations for linear and volumetric thermal expansion coefficients. The thermal expansion coefficient of metals generally increases with decreasing melting point.
[3] Thermal conductivity in metals occurs via conduction electrons, while in nonmetals it occurs via phonon vibrations
High pressure structural properties of rare earth antimonideAlexander Decker
1) The document investigates the high-pressure structural phase transition of rare-earth antimonide DySb using a three-body potential model with electronic polarizability.
2) This model predicts a first-order phase transition from the NaCl (B1) structure to the CsCl (B2) structure in DySb at 22.6 GPa, with a 3.8% volume collapse.
3) The predicted transition pressure and volume change are in good agreement with available experimental data.
Study on rare-earth–doped type-I germanium clathratesYang Li
The synthesis of rare-earth clathrates RExBa8xGa16Ge30 is a challenging task. The Group IV clathrates with rare-earth doping are hardly to be experimentally prepared, except Eu clathrate. In the current study, the first-principle method based on the density functional theory was implemented. The effects of the various RE elements doping on the binding energy and chemical reaction drive energy were studied by optimizing the phase structure. The energy calculations suggest that it is difficult to synthesize RE clathrates without Ga doping. The function of Ga doping is to effectively increase the drive chemical reaction in order to synthesize the clathrates. The simulation shows that, besides Eu, other rare-earth elements, such as Sm, Nd, and Yb can also enter cage lattice in the considering of drive energy, thus making it possible to synthesize the (RE,Ba)8Ge30Ga16 clathrates.
Research Inventy : International Journal of Engineering and Scienceresearchinventy
This document summarizes a research study on the thermoluminescence properties of nanocrystalline europium-doped barium sulfate (BaSO4:Eu) phosphor. Key findings include:
1) Nanocrystalline BaSO4:Eu powder was successfully synthesized via a chemical co-precipitation technique and characterized using XRD and TEM analysis.
2) TL measurements showed a single prominent dosimetric peak around 456 K, above room temperature, making the material suitable for radiation dosimetry.
3) The material exhibited a linear dose response up to 100 Gy. Deconvolution of the TL glow curve identified two trap centers responsible for the observed luminescence
Fluorescence quenching of 5-methyl-2-phenylindole (MPI) by carbon tetrachlori...IOSR Journals
The fluorescence quenching of 5-methyl-2-phenylindole (MPI) by carbon tetrachloride by steady state in different solvents, and by transient method in benzene has been carried out at room temperature. The Stern–Volmer (SV) plot has been found to be non-linear with a positive deviation for all the solvents studied. In order to interpret these results we have invoked the ground state complex and sphere of action static quenching models. Using these models various rate parameters have been determined. The magnitudes of these parameters imply that sphere of action static quenching model agrees well with the experimental results. Hence the positive deviation in the SV plots is attributed to the static and dynamic quenching. Further, from the studies of temperature dependence of rate parameters and lifetime measurements, it could be explained that the positive deviation is due to the presence of a small static quenching component in the overall dynamic quenching. With the use of finite sink approximation model, it was possible to check whether these bimolecular reactions as diffusion limited and to estimate independently distance parameter R′ and mutual diffusion coefficient D. Finally an effort has been made to correlate the values of R′ and D with the values of the encounter distance R and the mutual diffusion coefficient D determined using the Edward's empirical relation and Stokes–Einstein relation.
This study examines the clustering properties and redshift evolution of bias for 593 X-ray selected AGN from the XMM-Newton survey in the COSMOS field with spectroscopic redshifts below z=4. The authors find evidence that the bias factor increases with redshift for the total AGN population, from b=2.30 at z=0.92 to b=4.37 at z=1.94. Splitting the sample, they observe a similar increase in bias with redshift for broad-line and unobscured AGN, corresponding to a constant halo mass of logM~13.28 and logM~13, respectively. The observed bias factors cannot be reproduced by models assuming AGN are triggered
SIMULATION OF GENERATION OF HIGH PRESSURE AND TEMPERATURE IN METALS UNDER SHO...IJORCS
This document simulates the generation of high pressure and temperature in metals under shock loading. It presents equations to model the total pressure and energy behind a shock front in metals. The pressure is modeled as a function of density ratio and temperature, taking into account cold, thermal, and excitation pressures. Results show that as the shock wave converges towards the center of a spherical metal sample, excitation pressure dominates over elastic and thermal pressures. Graphs show the variation of pressure and temperature in different metals like aluminum, iron, stainless steel, molybdenum, and iridium as the shock wave moves inward. Thermal pressure initially increases then levels off, while excitation pressure rises very fast before decreasing as the shock nears the center
First principles study of electronic, elastic and thermal properties of b2 ty...Alexander Decker
This document reports on a first principles study of the electronic, elastic, and thermal properties of RECd (RE = La, Ce, and Pr) intermetallic compounds using density functional theory. The compounds were found to be metallic in nature. Elastic constants were calculated and satisfied mechanical stability criteria, though values have not been experimentally measured. Among the compounds, PrCd was predicted to be most ductile based on its bulk to shear modulus ratio. Thermal properties like Debye temperature were also derived from the calculated elastic constants. This study provides the first theoretical predictions of elastic properties of these RECd intermetallic compounds.
This document discusses the hydrodynamic equations that describe neutral gas and plasma, and how they are modified to become the magnetohydrodynamic (MHD) equations when a conducting fluid is in a magnetic field. It introduces the continuity, momentum, and entropy equations for neutral gas hydrodynamics. It then explains how these are updated to the MHD equations by adding magnetic forces and Ohm's law relating current and fields. The key MHD equations derived include equations for momentum, entropy, and the magnetic field evolving due to motion and diffusion.
Electronic structure of strongly correlated materials Part II V.AnisimovABDERRAHMANE REGGAD
This document summarizes applications of the LDA+U and LDA+DMFT methods to strongly correlated materials. It discusses how these methods can accurately model Mott insulators, charge order, spin order, orbital order, and other phenomena. Specific examples discussed include charge ordering in Fe3O4, orbital ordering in KCuF3 and LaMnO3, and the spin state of Co3+ in LaCoO3. It also outlines the theoretical foundations and computational schemes of the LDA+U and LDA+DMFT methods, such as how the quantum Monte Carlo method can be used to solve the effective impurity problem in LDA+DMFT.
Dielectric Relaxation And Molecular Interaction Studies Of PEG With Non-Polar...IOSR Journals
This document discusses a study of the dielectric relaxation and molecular interactions of polyethylene glycol (PEG) with non-polar solvents like carbon tetrachloride, benzene, and 1,4-dioxane using time domain reflectometry technique. The complex dielectric permittivity was measured for PEG-solvent mixtures at different concentrations from 10 MHz to 30 GHz. Parameters like the static dielectric constant, relaxation time, Bruggeman factor, and Kirkwood correlation factors were determined. The results indicate that heteromolecular hydrogen bonding between PEG and the solvents significantly affects the dielectric properties of the mixtures.
Quantum-Gravity Thermodynamics, Incorporating the Theory of Exactly Soluble Active Stochastic Processes, with Applications
by Daley, K.
Published in IJTP in 2009. http://adsabs.harvard.edu/abs/2009IJTP..tmp...67D
W. Buchmüller: Cosmological B-L Breaking: Baryon Asymmetry, Dark Matter and G...SEENET-MTP
1) Cosmological B−L breaking can provide a unified explanation for inflation, baryogenesis via leptogenesis, and dark matter in the form of gravitinos or higgsinos/winos. Spontaneous breaking of B−L symmetry at high scales generates heavy neutrino masses and can drive hybrid inflation.
2) Decay of the false vacuum after hybrid inflation reheats the universe and produces an initial population of particles. Boltzmann equations track the evolution and show this process can successfully generate the observed baryon asymmetry via leptogenesis and dark matter density in gravitinos.
3) Relic gravitational waves provide a potential test, with contributions predicted from inflation, preheating after inflation ends, and cosmic
Nucleation III: Phase-field crystal modeling of nucleation processPFHub PFHub
The document summarizes research on modeling nucleation processes using phase-field crystal modeling. It discusses how phase-field crystal models can capture nucleation and growth phenomena observed in experiments and atomistic simulations. Specifically, it describes how different phase-field crystal models are able to simulate:
1) Homogeneous and heterogeneous nucleation processes in 2D and 3D, including the effects of lattice mismatch and particle-induced nucleation.
2) Continuous cooling simulations that show amorphous phase formation prior to crystallization, similar to experimental observations in colloids.
3) Instantaneous quenching simulations that produce amorphous clusters and domains that facilitate heterogeneous nucleation of body-centered cubic crystals.
4
This document summarizes a molecular dynamics study of the stacking interactions between nucleobase pairs in dinucleoside monophosphates in aqueous solution. 32 dinucleoside monophosphates containing adenine, thymine, cytosine and guanine were simulated for 40 nanoseconds. A reaction coordinate was defined to quantify stacked and unstacked states based on the distance and angle between nucleobase planes. Free energies were calculated for all base pair combinations, with AG stacking being most favorable and TT/CC stacking least favorable. The presence of a 2'-OH group in RNA dinucleosides increased stacking but decreased compactness relative to DNA. Base dipole orientations in stacked states were also analyzed.
This lecture covered enzymatic catalysis and enzyme kinetics. It discussed how enzymes speed up reactions by lowering the activation energy and transition state through substrate binding and use of catalytic groups. It also described Michaelis-Menten enzyme kinetics and different inhibition mechanisms like competitive and noncompetitive inhibition. Single-molecule studies reveal enzymes have dynamic conformations that result in a distribution of catalytic activities.
Sainsbury's plans to redevelop its regional distribution depot in Basingstoke to provide a modern, more efficient facility. The existing 300,000 sq ft depot built in 1964 is outdated and at full capacity. The proposed redevelopment will increase distribution efficiency, secure Sainsbury's long-term future in Basingstoke, and safeguard existing jobs. Construction of the new 15-hectare site will begin in November 2011 if planning approval is granted.
The Houston retail market posted positive net absorption of 397,000 square feet in Q1 2013, with vacancy declining slightly to 7.0%. Rental rates increased to an average of $14.68 per square foot. New retail space under construction totaled 585,000 square feet. The Houston job market and economy remained strong, with 118,700 new jobs added in the last year and unemployment falling to 6.3%.
I am a marketing and policy practitioner with a master’s degree in public policy and over four years experience in marketing project management. Here is my resume.
Bill Campbell, chairman of Intuit and mentor to many Silicon Valley companies, believes that innovation starts with product-focused engineers leading development. He discusses how companies like Google strive to invent new products and services, while others like Apple focus on perfecting technology to create seamless consumer experiences. Campbell has seen both breakthrough innovations and failed startups over his career. He emphasizes the importance of founding teams that care about building durable companies with lasting value through intellectual property and competitive advantages.
Effect of sodium doping on thermal properties of perovskite r mn o3 for poten...Alexander Decker
This document discusses the effect of sodium doping on the thermal properties of perovskite rare earth manganites RMnO3 for potential magnetoelectric applications. It studies the thermal, elastic, and cohesive properties of sodium-doped rare earth manganites R1-xNaxMnO3 (R3+ = La, Pr, Tb) using a modified rigid ion model and atom in molecules theory. It finds that sodium doping increases the A-site cation radius, affecting properties like lattice specific heat, Debye temperature, thermal expansion, bulk modulus, and cohesive energy. These thermal properties are important for determining the compatibility of components in thermoelectric devices and revealing electron-lattice coupling in
The document summarizes research on the magnetic properties and magnetocaloric effect of two materials: La2NiMnO6 nanocrystals and a single crystal of La1.2Sr1.8Mn2O7. For both materials, the document examines structural properties, magnetic phase transitions, critical behavior near the Curie temperature, and magnetocaloric effects. Key results include determining the materials undergo second-order phase transitions and exhibit short-range ferromagnetic order. The magnetocaloric effect is also investigated through measurements of magnetic entropy change and development of universal curves for both materials.
In the focus of attention at the present time are the new rare earth‐cobalt‐based magnet alloys. This paper is primarily a qualitative review of the physical phenomena controlling their behavior and of the materials problems these magnets have posed. It also provides an outlook at possibilities for the development of still better or cheaper permanent magnets which current research on rare earth‐ transition metal alloys appears to provide. The origins of the magnetic moments and the crystal anisotropy of rare earth‐transition metal phases are discussed. Alternative concepts of the causes of coercivity in powders and sintered bodies are analyzed. Some basic aspects of the sintering of R‐Co compacts and the magnetic hardening of R–Co–Cu alloys in the massive state are reviewed. Specific problems related to particular alloys and applications of the magnets are pointed out. The conclusion is drawn that the new family of permanent magnets now emerging rivals in complexity both the Alnicos and the ferrites together. There are many development opportunities for the future, and we can expect that, eventually, magnets based on high‐anisotropy alloys containing rare earths will be offered in a variety of grades, covering a wide range of properties and prices, and that they will be produced by several drastically different methods.
Presentation of Licentiate in Physics Engineering of Francisco AlmeidaFrancisco Almeida
This seminar was presented to show the results of my research on magnetic thin films for my Licentiate diploma in Physics Engineering. This is a subset (although the biggest portion) of the analysis performed.
(note: the two last slides are not part of the actual presentation).
Revisiting the magnetic and magnetocaloric properties of FeZrB Invar alloys u...Universidad de Oviedo
This document summarizes research on the magnetic and magnetocaloric properties of FeZrB Invar alloy ribbons. Key findings include:
1) The Curie temperature, peak magnetic entropy change, and peak temperature decrease with increasing Fe content in the alloys.
2) The alloys exhibit large refrigerant capacity values due to the combination of low peak entropy change but broad entropy change curves.
3) A two-phase composite of the alloys leads to an increased width of the entropy change curves and a flattened overall entropy change curve, enhancing refrigerant capacity.
This document discusses a proposed spin filter device consisting of a ferromagnetic scanning tunneling microscope (STM) tip above a metallic surface containing a Kondo adatom.
The combined effects of the Kondo screening, quantum interference between tunneling paths, and the tip magnetism are studied theoretically. It is found that for certain tip-adatom distances and bias voltages, the tunneling current can be nearly 100% spin polarized, making this a potential spin filter or polarizer.
The conductance formula is derived taking into account the Fano lineshape from quantum interference and the splitting of the Kondo resonance into two spin components from the exchange interaction with the tip. For an optimized configuration, one spin channel is suppressed,
Study of Boron Based Superconductivity and Effect of High Temperature Cuprate...IOSR Journals
This paper illustrates the main normal and Boron superconducting state temperature properties of magnesium diboride, a substance known since early 1950's, but lately graded to be superconductive at a remarkably high critical temperature Tc=40K for a binary synthesis. What makes MgB2 so special? Its high Tc, simple crystal construction, large coherence lengths, high serious current densities and fields, lucidity of surface boundaries to current promises that MgB2 will be a good material for both large scale applications and electronic devices. Throughout the last seven month, MgB2 has been fabricated in various shape, bulk, single crystals, thin films, ribbons and wires. The largest critical current densities >10MA/cm2 and critical fields 40T are achieved for thin films. The anisotropy attribution inferred from upper critical field measurements is still to be resolved, a wide range of values being reported, γ = 1.2 ÷ 9. Also there is no consensus about the existence of a single anisotropic or double energy cavity. One central issue is whether or not MgB2 represents a new class of superconductors, being the tip of an iceberg that waits to be discovered. Until now MgB2 holds the record of the highest Tc among simple binary synthesis. However, the discovery of superconductivity in MgB2 revived the interest in non-oxides and initiated a search for superconductivity in related materials, several synthesis being already announced to become superconductive: TaB2, BeB2.75, C-S composites, and the elemental B under pressure.
This document summarizes a study that models the thermal conductivity of graphite nanosheet (GNS)/epoxy composites. An effective medium model is used to analyze how the thermal conductivity of these composites is affected by the aspect ratio and orientation of the GNS, as well as the interfacial thermal resistance between the GNS and polymer matrix. The model predicts that the interfacial thermal resistance between GNS and polymers is about one order of magnitude lower than between carbon nanotubes and polymers, potentially explaining the high thermal conductivity observed experimentally for GNS/epoxy composites.
This document summarizes ab initio quantum mechanical calculations performed to study the mechanical and thermodynamic properties of calcium carbonate polymorphs, including calcite, aragonite, and vaterite. The calculations were carried out using the CRYSTAL code to determine properties such as lattice parameters, vibrational frequencies, elastic moduli, thermal expansion, and phase transitions at pressures up to 30 GPa and temperatures from 298-700 K. The results from these calculations agree well with available experimental data and provide an exclusive investigation of the properties of calcium carbonate polymorphs.
This document discusses a fusion-driven rocket (FDR) concept for rapid interplanetary travel. It summarizes the FDR approach, which uses magneto-inertial fusion to directly convert fusion energy into propulsive energy through a thick metal blanket and magnetic nozzle. Initial mission studies show the FDR could enable 30-day and 90-day missions to Mars, with the 30-day option providing the fastest transit but lower payload mass fraction, while the 90-day option allows higher payload but a longer trip. Further development is needed to advance the FDR concept to a technology readiness level of 5 through experiments and additional mission analysis.
The document discusses developments in the theory of x-ray absorption and Compton scattering. It focuses on using the Compton profile to study warm dense matter by extracting equations of state information from x-ray scattering data. Molecular dynamics simulations are used to model thermal disorder effects on the Compton profile at high temperatures and densities relevant to warm dense matter regimes. The Compton profile is calculated from the molecular dynamics snapshots to account for disorder beyond perfect crystal calculations.
BoltzTraP is a software tool that uses linearized Boltzmann transport theory to calculate electronic transport properties from first-principles band structures. It can calculate properties like electrical conductivity, Seebeck coefficient, and electronic thermal conductivity. The document discusses applications of BoltzTraP to analyze transport properties of metals and thermoelectric materials. Key applications highlighted include analyzing anisotropy, resistivity temperature dependence, and optimizing the electronic structure of materials for high thermoelectric performance.
International Refereed Journal of Engineering and Science (IRJES)irjes
a leading international journal for publication of new ideas, the state of the art research results and fundamental advances in all aspects of Engineering and Science. IRJES is a open access, peer reviewed international journal with a primary objective to provide the academic community and industry for the submission of half of original research and applications.
This is the summary of a study we conducted to simulate heat transfer in one dimension of same and alternating mass systems using statistical mechanics and molecular dynamics.
This document summarizes research manipulating the coercivity of cobalt ferrite nanoparticles by changing particle size. Cobalt ferrite nanoparticles were synthesized with sizes ranging from 6 to 44 nm through calcination of a precursor at temperatures from 300 to 1200 degrees Celsius. X-ray diffraction characterization confirmed the crystal structure and particle sizes calculated using the Scherrer formula. Magnetic characterization using VSM found that coercivity reached a maximum of 645 Oe for 19 nm particles due to thermal effects and magnetic anisotropy in the nano-range. Smaller particles also exhibited lower saturation magnetization attributed to greater surface spin disorder. Future work could further investigate the mechanism of surface spin disorder through magnetic domain imaging.
New Constraints on Warm Dark Matter from the Lyman-α Forest Power SpectrumSérgio Sacani
The forest of Lyman-α absorption lines detected in the spectra of distant quasars encodes information on the nature and properties of dark matter and the thermodynamics of diffuse baryonic
material. Its main observable – the 1D flux power spectrum (FPS) – should exhibit a suppression on
small scales and an enhancement on large scales in warm dark matter (WDM) cosmologies compared
to standard ΛCDM. Here, we present an unprecedented suite of 1080 high-resolution cosmological
hydrodynamical simulations run with the Graphics Processing Unit-accelerated code Cholla to
study the evolution of the Lyman-α forest under a wide range of physically-motivated gas thermal
histories along with different free-streaming lengths of WDM thermal relics in the early Universe. A
statistical comparison of synthetic data with the forest FPS measured down to the smallest velocity
scales ever probed at redshifts 4.0 ∼
< z ∼
< 5.2 [1] yields a lower limit mWDM > 3.1 keV (95 percent
CL) for the WDM particle mass and constrains the amplitude and spectrum of the photoheating
and photoionizing background produced by star-forming galaxies and active galactic nuclei at these
redshifts. Interestingly, our Bayesian inference analysis appears to weakly favor WDM models with a
peak likelihood value at the thermal relic mass of mWDM = 4.5 keV. We find that the suppression of
the FPS from free-streaming saturates at k ∼
> 0.1 s km−1 because of peculiar velocity smearing, and
this saturated suppression combined with a slightly lower gas temperature provides a moderately
better fit to the observed small-scale FPS for WDM cosmologies.
This document discusses magnetic deflagration and detonation in nanomagnets and manganites. It summarizes previous work on magnetic avalanches in these materials and introduces the concept of quantum magnetic deflagration. Key findings include observing deflagration fronts propagating at resonant magnetic fields and a potential deflagration to detonation transition. The document also discusses using surface acoustic waves and high-frequency EPR to study spin dynamics, as well as observing magnetic deflagration and colossal resistivity changes in manganites.
This document presents a comparative study of the dynamic optical filtering and temperature sensing capabilities of one-dimensional binary and ternary photonic crystals (PHCs). The study finds that:
1) The binary PHC shows four optical bandgaps compared to seven bandgaps in the ternary PHC.
2) For temperatures between 100-700K, both PHCs show improved temperature sensing effectiveness as temperature increases, except for the first bandgap of the binary and the first two bandgaps of the ternary.
3) The binary PHC performs better as a temperature sensor between 840-1100nm, but the ternary PHC outperforms at longer wavelengths.
4)
Similar to Enhancing the working temperature span and refrigerant capacity of two-phase composite systems based on amorphous FeZrBCu ribbons (20)
Este documento presenta una introducción a la refrigeración magnética. Explica los beneficios de esta tecnología como una alternativa más eficiente y respetuosa con el medio ambiente que la refrigeración tradicional. Describe los diferentes tipos de materiales magnetocalóricos, incluyendo aleaciones con memoria de forma magnética y cintas de Ni-Mn-Sn y Ni-Mn-In. También cubre temas como la determinación del efecto magnetocalórico a través de medidas directas e indirectas y los requisitos para materiales con transic
Magnetocaloric effect and magnetic field-induced martensitic transformation i...Universidad de Oviedo
One of the challenges of modern societies consists in to increase the equipment energy efficiency, whereby reducing the energy consumption. In this sense, the magnetic solid-state refrigeration technology based on the magnetocaloric effect (MCE), attracts an enormous interest because of its potential to substitute the conventional liquid-gas refrigerant systems due to, among other advantages, its superior efficiency (up to 60% of Carnot's cycle) [1,2]. However, to be commercially competitive, this technology still needs cheap materials with enhanced refrigerant properties. Among the potential materials, metamagnetic shape memory alloys (mainly, Heusler-type Ni-Mn-based alloys) occupy a unique place because, alongside the shape memory effect and superelasticity, they exhibit large magnetocaloric effect due to the sharp change of the magnetization associated to the magnetostructural martensitic transformation (MT) [4].
We will present our recent studies of both the magnetocaloric effect and the influence of magnetic field on MT in metamagnetic Ni-Mn-In alloys doped by Cu and Cr. This doping mode allows a fine tuning of both the MT temperature around the room temperature (278-315 K) and magnetization drop at MT. The adiabatic MCE measurements have been performed using in-house made set-up [3]. An application of 1.9 T magnetic field results in a maximum inverse adiabatic temperature change of ~ -2 K caused by magnetic field-induced MT. Besides, the austenite phase undergoes a ferro-to-paramagnetic transition to which a direct adiabatic temperature change of almost the same amplitude as for inverse effect is associated. Furthermore, MT moves to lower temperatures (around 40 K for Cu-doped alloy) in magnetic fields up to 10 T accompanied by a decrease of the transformation entropy change.
References:
1. M.-H. Phan and S.-C. Yu, J. Magn. Magn. Mater. 308, 325 (2007).
2. V. Franco, J.S. Blázquez, B. Ingale, and A. Conde, Annu. Rev. Mater. Res. 42, 305 (2012).
3. V.A. Chernenko et al., J. Magn. Magn. Mater. 324, 3519 (2012).
4. P. Álvarez-Alonso et al., Key Eng. Mater. 644, 215–218 (2015).
This document summarizes the fabrication of patterned ferromagnetic shape memory thin films. It discusses two routes for micropatterning Ni-Mn-Ga thin films using self-assembled polystyrene spheres and reactive ion etching. Route 1 uses a Si sacrificial layer deposited at 500°C, while Route 2 produces arrays of Ni-Mn-Ga antidots at room temperature followed by annealing at 500°C. Characterization shows the patterned films via Route 2 exhibit ferromagnetism up to 100°C and a spread martensitic transformation, demonstrating their functional properties. Route 1 showed promise but requires further optimization.
Efecto magnetocalórico en materiales con transicion de segundo ordenUniversidad de Oviedo
Este documento trata sobre el efecto magnetocalórico en materiales con transición de segundo orden. Describe la introducción al efecto magnetocalórico y la refrigeración magnética, estudios realizados sobre materiales con alta capacidad refrigerante como cintas amorfas en el sistema FeZrBCu e intermetálicos cristalinos y nanocristalinos R2Fe17, y ofrece conclusiones sobre cómo optimizar el efecto magnetocalórico.
Nuevas oportunidades para el desarrollo de refrigerantes magneticos: compos...Universidad de Oviedo
Este documento presenta una investigación sobre nuevos materiales magnético-calóricos compuestos para su uso como refrigerantes. Discuten la importancia de que la curva de variación de entropía magnética con la temperatura (ΔSM) sea constante para lograr mayor eficiencia en la refrigeración magnética. Presentan estudios sobre compuestos bifásicos basados en cintas amorfas de FeZrBCu, mostrando que pueden lograr una curva ΔSM tipo "tabla", similar a materiales de primer y segundo orden. Finalmente, anticipan el estudio de
Se ha caracterizado magnéticamente cintas nanoperm de
distintas composiciones, con el objetivo de estudiar cómo varía la impedancia con el campo magnético, efecto
conocido como Magneto-Impedancia, tanto en el estado as-quenched como tras recocerlas durante una hora a 600ºC.
Se ha elegido este tipo de materiales porque presenta un comportamiento magnético muy prometedor, sobre todo tras la nanocristalización, para obtener un fuerte efecto de la Magneto-Impedancia, así como muy buena sensibilidad al
campo magnético, lo cual es deseable para diversas aplicaciones relacionadas con sensores magnéticos.
Efectos Magnetovolúmico y Magnetocalórico en el compuesto Nd2Fe17Universidad de Oviedo
I. El documento caracteriza estructural y magnéticamente el compuesto Nd2Fe17 y estudia su efecto magnetovolumétrico y magnetocalórico.
II. Se encontró que el compuesto cristaliza en la fase Th2Ni17 y muestra una variación de volumen de celda anómala.
III. Presenta una transición de fase de segundo orden con una temperatura de Curie cercana a la ambiental, mostrando un valor de refrigeración magnética comparable al de Gd pero con menor costo de fabricación.
Efectos Magnetovolúmico y Magnetocalórico en el compuesto Nd2Fe17Universidad de Oviedo
Trabajo de investigación sobre el efecto magnetocalórico presente en el compuesto intermetálico Nd2Fe17, y su relación con las anomalías de magnetovolumen.
This thesis examines the magnetocaloric and magnetovolume effects in two families of iron-rich compounds: R2Fe17 alloys and FeZrBCu amorphous ribbons. The R2Fe17 alloys were synthesized by arc melting and can crystallize in two structures depending on the rare earth element. FeZrBCu amorphous ribbons were produced by rapid quenching and their Curie temperature depends on iron content. Both families show second-order magnetic transitions near room temperature. The effects of mechanical milling on the microstructure and magnetic properties of Pr2Fe17 and Nd2Fe17 alloys are also studied. Combining amorphous ribbons of different compositions increases refrigeration capacity
The document discusses magnetocaloric effects and magnetovolume anomalies in iron-based alloys. It introduces the magnetocaloric effect and how it relates to entropy changes and temperature shifts under applied magnetic fields. Two types of alloys studied are R2Fe17 compounds that can crystallize in rhombohedral or hexagonal structures depending on the rare earth element, and FeZrBCu amorphous alloys. The document outlines experimental techniques for fabrication and characterization of these materials and presents results on their magnetic properties and magnetocaloric behavior.
ISO/IEC 27001, ISO/IEC 42001, and GDPR: Best Practices for Implementation and...PECB
Denis is a dynamic and results-driven Chief Information Officer (CIO) with a distinguished career spanning information systems analysis and technical project management. With a proven track record of spearheading the design and delivery of cutting-edge Information Management solutions, he has consistently elevated business operations, streamlined reporting functions, and maximized process efficiency.
Certified as an ISO/IEC 27001: Information Security Management Systems (ISMS) Lead Implementer, Data Protection Officer, and Cyber Risks Analyst, Denis brings a heightened focus on data security, privacy, and cyber resilience to every endeavor.
His expertise extends across a diverse spectrum of reporting, database, and web development applications, underpinned by an exceptional grasp of data storage and virtualization technologies. His proficiency in application testing, database administration, and data cleansing ensures seamless execution of complex projects.
What sets Denis apart is his comprehensive understanding of Business and Systems Analysis technologies, honed through involvement in all phases of the Software Development Lifecycle (SDLC). From meticulous requirements gathering to precise analysis, innovative design, rigorous development, thorough testing, and successful implementation, he has consistently delivered exceptional results.
Throughout his career, he has taken on multifaceted roles, from leading technical project management teams to owning solutions that drive operational excellence. His conscientious and proactive approach is unwavering, whether he is working independently or collaboratively within a team. His ability to connect with colleagues on a personal level underscores his commitment to fostering a harmonious and productive workplace environment.
Date: May 29, 2024
Tags: Information Security, ISO/IEC 27001, ISO/IEC 42001, Artificial Intelligence, GDPR
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Strategies for Effective Upskilling is a presentation by Chinwendu Peace in a Your Skill Boost Masterclass organisation by the Excellence Foundation for South Sudan on 08th and 09th June 2024 from 1 PM to 3 PM on each day.
LAND USE LAND COVER AND NDVI OF MIRZAPUR DISTRICT, UPRAHUL
This Dissertation explores the particular circumstances of Mirzapur, a region located in the
core of India. Mirzapur, with its varied terrains and abundant biodiversity, offers an optimal
environment for investigating the changes in vegetation cover dynamics. Our study utilizes
advanced technologies such as GIS (Geographic Information Systems) and Remote sensing to
analyze the transformations that have taken place over the course of a decade.
The complex relationship between human activities and the environment has been the focus
of extensive research and worry. As the global community grapples with swift urbanization,
population expansion, and economic progress, the effects on natural ecosystems are becoming
more evident. A crucial element of this impact is the alteration of vegetation cover, which plays a
significant role in maintaining the ecological equilibrium of our planet.Land serves as the foundation for all human activities and provides the necessary materials for
these activities. As the most crucial natural resource, its utilization by humans results in different
'Land uses,' which are determined by both human activities and the physical characteristics of the
land.
The utilization of land is impacted by human needs and environmental factors. In countries
like India, rapid population growth and the emphasis on extensive resource exploitation can lead
to significant land degradation, adversely affecting the region's land cover.
Therefore, human intervention has significantly influenced land use patterns over many
centuries, evolving its structure over time and space. In the present era, these changes have
accelerated due to factors such as agriculture and urbanization. Information regarding land use and
cover is essential for various planning and management tasks related to the Earth's surface,
providing crucial environmental data for scientific, resource management, policy purposes, and
diverse human activities.
Accurate understanding of land use and cover is imperative for the development planning
of any area. Consequently, a wide range of professionals, including earth system scientists, land
and water managers, and urban planners, are interested in obtaining data on land use and cover
changes, conversion trends, and other related patterns. The spatial dimensions of land use and
cover support policymakers and scientists in making well-informed decisions, as alterations in
these patterns indicate shifts in economic and social conditions. Monitoring such changes with the
help of Advanced technologies like Remote Sensing and Geographic Information Systems is
crucial for coordinated efforts across different administrative levels. Advanced technologies like
Remote Sensing and Geographic Information Systems
9
Changes in vegetation cover refer to variations in the distribution, composition, and overall
structure of plant communities across different temporal and spatial scales. These changes can
occur natural.
Temple of Asclepius in Thrace. Excavation resultsKrassimira Luka
The temple and the sanctuary around were dedicated to Asklepios Zmidrenus. This name has been known since 1875 when an inscription dedicated to him was discovered in Rome. The inscription is dated in 227 AD and was left by soldiers originating from the city of Philippopolis (modern Plovdiv).
How to Setup Warehouse & Location in Odoo 17 InventoryCeline George
In this slide, we'll explore how to set up warehouses and locations in Odoo 17 Inventory. This will help us manage our stock effectively, track inventory levels, and streamline warehouse operations.
Walmart Business+ and Spark Good for Nonprofits.pdfTechSoup
"Learn about all the ways Walmart supports nonprofit organizations.
You will hear from Liz Willett, the Head of Nonprofits, and hear about what Walmart is doing to help nonprofits, including Walmart Business and Spark Good. Walmart Business+ is a new offer for nonprofits that offers discounts and also streamlines nonprofits order and expense tracking, saving time and money.
The webinar may also give some examples on how nonprofits can best leverage Walmart Business+.
The event will cover the following::
Walmart Business + (https://business.walmart.com/plus) is a new shopping experience for nonprofits, schools, and local business customers that connects an exclusive online shopping experience to stores. Benefits include free delivery and shipping, a 'Spend Analytics” feature, special discounts, deals and tax-exempt shopping.
Special TechSoup offer for a free 180 days membership, and up to $150 in discounts on eligible orders.
Spark Good (walmart.com/sparkgood) is a charitable platform that enables nonprofits to receive donations directly from customers and associates.
Answers about how you can do more with Walmart!"
Gender and Mental Health - Counselling and Family Therapy Applications and In...PsychoTech Services
A proprietary approach developed by bringing together the best of learning theories from Psychology, design principles from the world of visualization, and pedagogical methods from over a decade of training experience, that enables you to: Learn better, faster!
Enhancing the working temperature span and refrigerant capacity of two-phase composite systems based on amorphous FeZrBCu ribbons
1. Introduction Results Conclusions
Enhancing the working temperature span and refrigerant
capacity of two-phase composite systems based on
amorphous FeZrBCu ribbons
P. Alvarez1 J.L. Sánchez-Llamazares2 P. Gorria1 J.A. Blanco1
1 University of Oviedo, Spain
2 Instituto Potosino de Investigación Científica y Tecnológica, Mexico
International Symposium on Metastable, Amorphous and Nanostructured
Materials
2. Introduction Results Conclusions
Outline
1 Introduction
Magnetocaloric Effect
Improving the Relative Cooling Power
2 Results
Magnetocaloric Properties
Combined System
3 Conclusions
3. Introduction Results Conclusions
Magnetocaloric Effect
The Magnetic Entropy Change and the Relative Cooling Power
Temperature dependence of
Magnetization for GdAl2 and its
relation with the MCE
Maxwell Relation
Isothermal Magnetic Entropy Change
H2 ∂M
∆S (T , H2 )P,∆H = dH
H1 ∂T P,H
4. Introduction Results Conclusions
Magnetocaloric Effect
The Magnetic Entropy Change and the Relative Cooling Power
Temperature dependence of Relative Cooling Power (RCP)
Magnetization for GdAl2 and its
relation with the MCE
Estimation of RCP
Peak
Maxwell Relation RCP1 (H) = |∆SM (H) | × δTFWHM
TH
Isothermal Magnetic Entropy Change RCP2 (H) = |∆SM (T , H)| dT .
TC
H2 ∂M
∆S (T , H2 )P,∆H = dH RCP3 (H) = max ∆Smag (T1 , H) × (T2 − T1 )
H1 ∂T P,H
5. Introduction Results Conclusions
Improving the Relative Cooling Power
Composite Compounds: an Effective way to Improve the RCP via the ∆SM (T ) Broadening
Past: Low Temperature
Magnetic Composites
T. Hashimoto et al., J. Appl. Phys. 62 (9)
(1987) 3873-3878
6. Introduction Results Conclusions
Improving the Relative Cooling Power
Composite Compounds: an Effective way to Improve the RCP via the ∆SM (T ) Broadening
Past: Low Temperature Recent: RCP Improvement around RT by
Magnetic Composites Using Magnetic Composites
T. Hashimoto et al., J. Appl. Phys. 62 (9)
(1987) 3873-3878 R. Caballero-Flores et al., Appl. Phys. Lett. 98 (2011) 102505
7. Introduction Results Conclusions
Improving the Relative Cooling Power
Composite Compounds: an Effective way to Improve the RCP via the ∆SM (T ) Broadening
Past: Low Temperature Recent: RCP Improvement around RT by
Magnetic Composites Using Magnetic Composites
T. Hashimoto et al., J. Appl. Phys. 62 (9)
(1987) 3873-3878 R. Caballero-Flores et al., Appl. Phys. Lett. 98 (2011) 102505
Further Comments
RCP Optimization for a Two-Phase
Magnetic Composite The Maximum Refrigeration Efficiency is
attained with Constant Magnetic Entropy
Shape of ∆SM (T ) Change curves.
δTC
A.M. Tishin and Y.I. Spichkin. Magnetocaloric Effect
Weight Fraction of Both Phases and Its Applications. Series in Condensed Matter
Physics, 1 edition (2003).
Applied Magnetic Field
8. Introduction Results Conclusions
FeZrBCu amorphous alloys
Nanoperm Alloys
∆SM (T ) for Nanoperm alloys
P. Alvarez et al., Intermetallics 18 (2010)
2464-2467
10. Introduction Results Conclusions
Advantages
Advantages of FeZrBCu alloys for their use in Two-Phase Composite Systems
Advantages
Easy to produce (Melt
spinning technique)
Low Cost (Fe-Based
alloys)
Large MS values
Second Order Magnetic
Phase Transition
Tunable TC in a wide range
Broad ∆SM (T ) curves
11. Introduction Results Conclusions
Advantages
Advantages of FeZrBCu alloys for their use in Two-Phase Composite Systems
Advantages Magnetization Isotherms
Easy to produce (Melt
spinning technique)
Low Cost (Fe-Based
alloys)
Large MS values
Second Order Magnetic
Phase Transition
Tunable TC in a wide range MS ≈ 125 − 135 emu g−1
Broad ∆SM (T ) curves
12. Introduction Results Conclusions
Advantages
Advantages of FeZrBCu alloys for their use in Two-Phase Composite Systems
Advantages Magnetization Isotherms
Easy to produce (Melt
spinning technique)
Low Cost (Fe-Based
alloys)
Large MS values
Second Order Magnetic
Phase Transition
Tunable TC in a wide range MS ≈ 125 − 135 emu g−1
Broad ∆SM (T ) curves
Typical Arrott Plot
13. Introduction Results Conclusions
Advantages
Advantages of FeZrBCu alloys for their use in Two-Phase Composite Systems
Advantages Magnetization Isotherms
Easy to produce (Melt
spinning technique)
Low Cost (Fe-Based
alloys)
Large MS values
Second Order Magnetic
Phase Transition
Tunable TC in a wide range MS ≈ 125 − 135 emu g−1
Broad ∆SM (T ) curves
TC vs Fe Content
Typical Arrott Plot
14. Introduction Results Conclusions
Advantages
Advantages of FeZrBCu alloys for their use in Two-Phase Composite Systems
Advantages Magnetization Isotherms
Easy to produce (Melt
spinning technique)
Low Cost (Fe-Based
alloys)
Large MS values
Second Order Magnetic
Phase Transition
Tunable TC in a wide range MS ≈ 125 − 135 emu g−1
Broad ∆SM (T ) curves
TC vs Fe Content
Typical Arrott Plot
15. Introduction Results Conclusions
Magnetocaloric Properties
Magnetic Entropy Change
A general view to ∆SM (T ) curves
for amorphous FeZrCuB alloys
16. Introduction Results Conclusions
Magnetocaloric Properties
Magnetic Entropy Change
A general view to ∆SM (T ) curves
for amorphous FeZrCuB alloys
17. Introduction Results Conclusions
Magnetocaloric Properties
Typical RCP and δTFWHM values of amorphous FeZrCuB alloys
RCP-1
Metallic Gd
RCP1(µ0 H = 5 T) = 687 Jkg−1
RCP2(µ0 H = 5 T) = 503 Jkg−1
RCP-2
18. Introduction Results Conclusions
Magnetocaloric Properties
Typical RCP and δTFWHM values of amorphous FeZrCuB alloys
RCP-1
Metallic Gd
RCP1(µ0 H = 5 T) = 687 Jkg−1
RCP2(µ0 H = 5 T) = 503 Jkg−1
Width of the ∆SM (T ) Curves
RCP-2
19. Introduction Results Conclusions
Combined System
A Concrete Two-Phase Composite based on amorphous FeZrCuB ribbons: EXAMPLE 1
∆SM (T ) curves of Component
A (Fe90 Zr9 B1 ) and B (Fe87 Zr6 B6 Cu1 )
20. Introduction Results Conclusions
Combined System
A Concrete Two-Phase Composite based on amorphous FeZrCuB ribbons: EXAMPLE 1
∆SM (T ) curves of Component ∆SM (T ) curves of the Composite System
A (Fe90 Zr9 B1 ) and B (Fe87 Zr6 B6 Cu1 ) 0.4 A + 0.6 B
21. Introduction Results Conclusions
Combined System
A Concrete Two-Phase Composite based on amorphous FeZrCuB ribbons: EXAMPLE 2
∆SM (T ) for the two-ribbon system
0.5 A (Fe87 Zr6 B6 Cu1 ) + 0.5 B (Fe90 Zr8 B2 )
22. Introduction Results Conclusions
Combined System
A Concrete Two-Phase Composite based on amorphous FeZrCuB ribbons: EXAMPLE 2
Increase of δTFWHM for the Two-Phase System
0.5 A (Fe87 Zr6 B6 Cu1 ) + 0.5 B (Fe90 Zr8 B2 )
∆SM (T ) for the two-ribbon system
0.5 A (Fe87 Zr6 B6 Cu1 ) + 0.5 B (Fe90 Zr8 B2 )
23. Introduction Results Conclusions
Combined System
A Concrete Two-Phase Composite based on amorphous FeZrCuB ribbons: EXAMPLE 2
Increase of δTFWHM for the Two-Phase System
0.5 A (Fe87 Zr6 B6 Cu1 ) + 0.5 B (Fe90 Zr8 B2 )
∆SM (T ) for the two-ribbon system
0.5 A (Fe87 Zr6 B6 Cu1 ) + 0.5 B (Fe90 Zr8 B2 )
Resulting RCP for the Two-Phase System
0.5 A (Fe87 Zr6 B6 Cu1 ) + 0.5 B (Fe90 Zr8 B2 )
RCP ≈ 95% of Metallic Gd
24. Introduction Results Conclusions
Combined System
Flattening of the ∆SM (T ) Curve
Flattening of ∆SM (T ) for the system
0.5 A (Fe87 Zr6 B6 Cu1 ) + 0.5 B (Fe90 Zr8 B2 )
25. Introduction Results Conclusions
Combined System
Flattening of the ∆SM (T ) Curve
Flattening of ∆SM (T ) for the system
0.5 A (Fe87 Zr6 B6 Cu1 ) + 0.5 B (Fe90 Zr8 B2 )
26. Introduction Results Conclusions
Conclusions
In this contribution we experimentally show that a combination
of two Nanoperm amorphous ribbons forming a two-phase
composite system may lead to:
A considerably increase of the δTFWHM with the consequent
enhancement in the RCP;
A Flattening of the ∆SM (T ) curve which improves the
refrigerant efficiency of the refrigerant thermodynamic cycle.
The latter is possible due to the broad ∆SM (T ) curve shown by
Nanoperm alloys and their combination in a proper way (i.e, the
right selection of both, the δTC of the two alloys chosen to form
the composite, and the relative weight fraction).
27. Introduction Results Conclusions
Conclusions
In this contribution we experimentally show that a combination
of two Nanoperm amorphous ribbons forming a two-phase
composite system may lead to:
A considerably increase of the δTFWHM with the consequent
enhancement in the RCP;
A Flattening of the ∆SM (T ) curve which improves the
refrigerant efficiency of the refrigerant thermodynamic cycle.
The latter is possible due to the broad ∆SM (T ) curve shown by
Nanoperm alloys and their combination in a proper way (i.e, the
right selection of both, the δTC of the two alloys chosen to form
the composite, and the relative weight fraction).
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