This paper studies the critical behaviours and magnetic properties of three-dimensional bond and anisotropy dilution Blume-Capel model （BCM） in the presence of an applied field within the effective field theory. The...This paper studies the critical behaviours and magnetic properties of three-dimensional bond and anisotropy dilution Blume-Capel model （BCM） in the presence of an applied field within the effective field theory. The trajectory of tricritical point, reentrant transitions and degenerate patterns of anisotropy are obtained both for the bond and the anisotropy dilutions. The global phase diagrams demonstrate unusually reentrant phenomena. The temperature dependences of magnetization curves undergo remarkable spin glass behaviour at low temperatures, and transform from ferromagnetism to paramagnetism at high temperature in applied fields. Temperature dependence of magnetic susceptibility curve is in qualitative agreement with experimental result.展开更多
HgCr2S4 is a typical compound manifesting competing ferromagnetic （FM） and antiferromagnetic （AFM） exchanges as well as strong spin-lattice coupling. Here we study these effects by intentionally choosing a combina...HgCr2S4 is a typical compound manifesting competing ferromagnetic （FM） and antiferromagnetic （AFM） exchanges as well as strong spin-lattice coupling. Here we study these effects by intentionally choosing a combination of magnetization under external hydrostatic pressure and thermal conductivity at various magnetic fields. Upon applying pressure up to 10 kbar at 1 kOe, while the magnitude of magnetization reduces progressively, the AFM ordering temperature TN enhances concomitantly at a rate of about 1.5 K/kbar. Strikingly, at lO kOe the field polarized FM state is found to be driven readily back to an AFM one even at only 5kbar. In addition, the thermal conductivity exhibits drastic increments at various fields in the temperature range with strong spin fluctuations, reaching about 30% at 50 kOe. Consequently, the results give new experimental evidence of spin-lattice coupling. Apart from the colossal magnetoeapacitance and colossal magnetoresistance reported previously, the findings here may enable new promising functionalities for potential applications.展开更多
In this paper,we focus on the two-dimensional pulsating nanofluid flow through a parallel-plate channel in the presence of a magnetic field.The pulsating flow is produced by an applied pressure gradient that fluctuate...In this paper,we focus on the two-dimensional pulsating nanofluid flow through a parallel-plate channel in the presence of a magnetic field.The pulsating flow is produced by an applied pressure gradient that fluctuates with a small amplitude.A kind of proper transformation is used so that the governing equations describing the momentum and thermal energy are reduced to a set of non-dimensional equations.The analytical expressions of the pulsating velocity,temperature,and Nusselt number of nanofluids are obtained by the perturbation technique.In the present study,the effects of the Cu-H2O and Al_(2)O_(3)-H2O nanofluids on the flow and heat transfer in pulsating flow are compared and analyzed.The results show that the convective heat transfer effect of Cu-H2O nanofluids is better than that of Al_(2)O_(3)-H2O nanofluids.Also,the effects of the Hartmann number and pulsation amplitude on the velocity,temperature,and Nusselt number are examined and discussed in detail.The present work indicates that increasing the Hartmann number and pulsation amplitude can enhance the heat transfer of the pulsating flow.In addition,selecting an optimal pulsation frequency can maximize the convective heat transfer of the pulsating flow.Therefore,improved understanding of these fundamental mechanisms is conducive to the optimal design of thermal systems.展开更多
It is well known that the critical current density of a superconductor depends on its size, shape, nature of doping and the manner of preparation. It is suggested here that the collective effect of such differences fo...It is well known that the critical current density of a superconductor depends on its size, shape, nature of doping and the manner of preparation. It is suggested here that the collective effect of such differences for different samples of the same superconductor is to endow them with different values of the Fermi energy—a single property to which may be attributed the observed variation in their critical current densities. The study reported here extends our earlier work concerned with the generalized BCS equations [Malik, G.P. (2010) Physica B, 405, 3475-3481;Malik, G.P. (2013) WJCMP, 3,103-110]. We develop here for the first time a framework of microscopic equations that incorporates all of the following parameters of a superconductor: temperature, momentum of Cooper pairs, Fermi energy, applied magnetic field and critical current density. As an application of this framework, we address the different values of critical current densities of Bi-2212 for non-zero values of temperature and applied magnetic field that have been reported in the literature.展开更多
The superexchange interaction on a magnetic ion may be represented by an effective field Hm =λM in some paramagnetic materials, here λis the coefficient of effective field and M = XHe with X being the magnetic susce...The superexchange interaction on a magnetic ion may be represented by an effective field Hm =λM in some paramagnetic materials, here λis the coefficient of effective field and M = XHe with X being the magnetic susceptibility and He being the applied field. The variation of the equivalent λX with the dynamic applied field is given and the crystal field-splitting levels of the excited configuration 4f75d1 of the Tb3＋ ion are calculated in the Tb3Ga5O12. By means of the effective field Hm and the applied field He, the Faraday rotation of Tb3CasO12 at 6 K and 41 K, under the high magnetic field and at 0.63μm wavelength, are presented. Our calculated results are in agreement with the experimental data.展开更多
To investigate the influence of stress alone on the stray field signals of ferromagnetic materials,the static tensile tests of 0.45%C steel and 45CrNiMoVA steel flat-shaped specimens were performed on an MTS810 hydrau...To investigate the influence of stress alone on the stray field signals of ferromagnetic materials,the static tensile tests of 0.45%C steel and 45CrNiMoVA steel flat-shaped specimens were performed on an MTS810 hydraulic testing machine. Hp（y） signals,the normal component of spontaneous stray field,were measured during the testing process by an EMS-2003 metal magnetic memory diagnostic apparatus cooperated with a non-magnetic electric control displacement instrument. Fracture and microstructure were observed by a scanning electronic microscope and a transmission electron microscope,respectively. The relationships between axial applied stress or residual stress measured by X-ray diffraction method and Hp（y） were analyzed. The results indicate that some regular pattern of the magnetic curve is displayed only between applied stress and stray field signals. The magnetic ordering process stops due to dislocation pinning magnetic domain structure,and Hp（y） value unvaried nearly with applied load increasing in the plastic deformation stage.展开更多
Adsorption characteristics of CO adsorbed on pristine 4,12,2-graphyne(4,12,2-G)and Fe-doped 4,12,2-graphyne(Fe-4,12,2-G)are studied by first-principles calculations.It is shown that CO is only physically adsorbed on p...Adsorption characteristics of CO adsorbed on pristine 4,12,2-graphyne(4,12,2-G)and Fe-doped 4,12,2-graphyne(Fe-4,12,2-G)are studied by first-principles calculations.It is shown that CO is only physically adsorbed on pristine 4,12,2-G.Fe atoms can be doped into 4,12,2-G stably and lead to band gap opening.After doping,the interaction between Fe-4,12,2-G and CO is significantly enhanced and chemisorption occurs.The maximum adsorption energy reaches-1.606 e V.Meanwhile,the charge transfer between them increases from 0.009e to 0.196e.Moreover,the electric field can effectively regulate the adsorption ability of the Fe-4,12,2-G system,which is expected to achieve the capture and release of CO.Our study is helpful to promote applications of two-dimensional carbon materials in gas sensing and to provide new ideas for reversible CO sensor research.展开更多
In the present study, kambala (botanical name: Chlorophora excelsa and Chlorophora regia) wood wastes were incorporated into stabilized earth bricks in order to test their acoustic insulation capacity of the walls;lea...In the present study, kambala (botanical name: Chlorophora excelsa and Chlorophora regia) wood wastes were incorporated into stabilized earth bricks in order to test their acoustic insulation capacity of the walls;leading to better waste management from the timber industry. Two methods have been applied to determine the influence of the wood waste content in the stabilized earth bricks, on the weakening of the level of noise reception coming from the environmental medium, in an apartment built with composite bricks (earth + wood chips + cement). This influence has also been analyzed on the magnetic field induced by these bricks. The results showed that the level of sound reception through these bricks decreases with increasing wood waste content regardless of the method used (from 110 dB to 68 dB, respectively for Φb = 0% and Φb = 8%). The kambala wood waste in cement-stabilized clay bricks induces a magnetic field that increases with the wood waste content;the high contents of the wood chips causing an increase in the magnetic permeability of the composite medium. The correlation between the noise level and the magnetic field of the bricks shows that the noise level declines with increasing magnetic induction of the bricks.展开更多
We utilize the effective field theory approach to study the properties of the axion. In particular, with s as well as u and d quarks regarded to be relatively light we derive a formula for the mass of the axion; a rou...We utilize the effective field theory approach to study the properties of the axion. In particular, with s as well as u and d quarks regarded to be relatively light we derive a formula for the mass of the axion; a rough estimate of the rate for its dominant decay mode at low energy is also carried out.展开更多
The paper is based on the development of a wood preservative without metal salts to be used in use classes 3 and 4 (EN 335), eco-friendly and harmless to humans and animals. Boric acid was used as a biocide, due to it...The paper is based on the development of a wood preservative without metal salts to be used in use classes 3 and 4 (EN 335), eco-friendly and harmless to humans and animals. Boric acid was used as a biocide, due to its effectiveness against fungi and insects. It is also known to be easily leached from wood exposed to weather action. Colloidal silica was therefore added in the formulations to guarantee the fixation of boric acid to wood. The different formulations were tested for the protective efficacy against decay fungi through laboratory tests (EN 113) and field trials (EN 252). The results were promising, especially those concerning boron fixation and efficacy against decay fungi through laboratory tests, where some formulations and retentions gave a durability class 1 (very durable) according to EN 350-1. The fourth evaluation, after 50 months of field trials showed only a slight difference between the treated samples and controls.展开更多
Motion is a ground-laying concept in physics. Its meaning however depends fundamentally on the assumptions about the nature of empty space. In Einstein’s theory of relativity (TR), no absolute references can be defin...Motion is a ground-laying concept in physics. Its meaning however depends fundamentally on the assumptions about the nature of empty space. In Einstein’s theory of relativity (TR), no absolute references can be defined and only relative motions are relevant. This however makes it impossible to understand why the motion of matter obeys the principle of inertia and why there exist laws of motion. The Higgs theory introduces radical changes in the current view about the nature of empty space. It introduces the idea that space is filled up by a real and very powerful quantum fluid medium, giving mass to the elementary particles by the Higgs mechanism. This Higgs Quantum Space (HQS) is locally an absolute reference for rest and for motions. It not only recovers an intrinsic meaning for motions, however literally governs the inertial motion of matter-energy. In this new scenario, the velocity of light is fixed with respect to the local HQS and velocity of matter with respect to the local HQS and not relative velocities are responsible for all the effects of motion. The Higgs mechanism is too responsible for the gravitational dynamics;because it is mass that creates the gravitational fields. Actually several clear experimental observations demonstrate that the HQS is moving round the sun consistently with the planetary motions. The present work therefore replaces Einstein’s spacetime curvature by a Keplerian velocity field of the HQS. This velocity field creates the ingenious outside-inside centrifuge mechanism of gravity. It also causes all the observed effects of the gravitational fields on light and on clocks.展开更多
The empirically reported values of the critical current density (<i>j<sub>c</sub></i>) of Bi-2212 as 2.4 × 10<sup>5</sup> (<i>j<sub>c</sub></i><sub&g...The empirically reported values of the critical current density (<i>j<sub>c</sub></i>) of Bi-2212 as 2.4 × 10<sup>5</sup> (<i>j<sub>c</sub></i><sub>1</sub>;Sample 1) and 1.0 × 10<sup>6</sup> A/cm<sup>2</sup> (<i>j<sub>c</sub></i><sub>2</sub>;Sample 2) are intriguing because both of them correspond to the <i>same</i> values of the temperature <i>T</i> = 4.2 K and the applied magnetic field <i>H</i> = 12 × 10<sup>4</sup> G. This difference is conventionally attributed to such factors—not all of which are quantifiable—as the geometry, dimensions and the nature of dopants and the manners of preparation of the samples which cause their granular structures, grain boundaries, alignment of the grains and so on to differ. Based on the premise that the chemical potential <i>μ</i> subsumes most of these features, given herein is a novel explanation of the said results in terms of the values of <i>μ</i> of the two samples. This paper revisits the problem that was originally addressed in [Malik G.P., Varma V.S. (2020) WJCMP, 10, 53-70] in the more accurate framework of a subsequent paper [Malik G.P., Varma V.S. (2021) JSNM, 34, 1551-1561]. Besides, it distinguishes between the contributions of the electro-electron (<i>e-e</i>) and the hole-hole (<i>h-h</i>) pairs to <i>j<sub>c</sub></i>—a feature to which no heed was paid earlier. The essence of our findings is that the <i>j<sub>c</sub></i>s of the two samples differ because they are characterized by different values of the <i>primary</i> variables <i>μ<sub>i</sub></i><sub> </sub>and <img src="Edit_e1b831e9-dc51-4c3b-bd84-fa905e3e62b5.png" alt="" />, where <img src="Edit_1f775a80-30ab-447d-861f-afb4ba8fba6a.png" alt="" /> is the effective mass of a charge-carrier and <i>m<sub>e</sub></i><sub> </sub>is the free-electron mass and <i>i</i> = 1 and 2 denote Sample 1 and Sample 2, respectively. In the scenario of the charge-carriers being <i>predominantly h-h</i> pairs, the values of these parameters are estimated to be: <i>μ</i><sub>1</sub> ≈ 12.3 meV, <i>η</i><sub>1</sub> ≈ 0.58;<i>μ</i><sub>2</sub> ≈ 22.7 meV, <i>η</i><sub>2</sub> ≈ 0.94. Following from these and similar estimates when the charge-carriers are <i>e-e</i> pairs, given below for each sample are the detailed results for the values of the <i>secondary</i> variables viz. the number density of the charge-carriers and their critical velocity, the number of occupied Landau levels and the magnetic interaction parameter.展开更多
Magnetic properties of composites prepared by coating lacquer containing neodymium iron boron （Nd-Fe-B） powders on rubberwood were characterized by vibrating sample magnetometry （VSM）, magnetic moment measurements...Magnetic properties of composites prepared by coating lacquer containing neodymium iron boron （Nd-Fe-B） powders on rubberwood were characterized by vibrating sample magnetometry （VSM）, magnetic moment measurements, and attraction tests with an iron-core solenoid. The Nd-Fe-B powders were recycled from electronic wastes by the ball-milling technique. Varying the milling time from 20 to 300 min, the magnetic squareness and the coercive field of the Nd-Fe-B powders were at the minimum when the powders were milled for 130 rain. It followed that the coercive field of the magnetic wood composites was increased with the milling time increasing from 130 to 300 min. For the magnetic wood composites using Nd-Fe-B obtained from the same milling time, the magnetic squareness and the coercive field were rather insensitive to the variation of Nd-Fe-B concentration in coating lacquer from 0.43 to 1.00 g/cm3. By contrast, the magnetization and magnetic moment were increased with the Nd-Fe-B concentration increasing. Furthermore, the electrical current in the solenoid required for the attraction of the magnetic wood composites was exponentially reduced with the increase in the amount of Nd-Fe-B used in the coating.展开更多
A double cascade-type four-level multiple-quantum-well-based exciton-biexciton transitions are proposed. The study is carried out on a 4.8-rim ZnSe single-quantum well which is embedded into ZnMgSSe cladding layers an...A double cascade-type four-level multiple-quantum-well-based exciton-biexciton transitions are proposed. The study is carried out on a 4.8-rim ZnSe single-quantum well which is embedded into ZnMgSSe cladding layers and pseudomor- phically grown by molecular beam epitaxy on a （0 0 1） GaAs substrate. It is displayed that the exciton spin relaxation and relative phases between applied fields can influence the transient and steady-state behaviors of absorption, dispersion, and group velocity of two weak probe and signal fields. Also, transient behaviors of electron population of different levels are discussed. It is found that the probe or signal amplification occurs in the absence of population inversion.展开更多
This paper makes some qualitative and quantitative analyses about halo formation rules of some mirror nuclei with the relativistic mean-field （RMF） theory and the Woods Saxon mean-field model. By analysing two oppos...This paper makes some qualitative and quantitative analyses about halo formation rules of some mirror nuclei with the relativistic mean-field （RMF） theory and the Woods Saxon mean-field model. By analysing two opposite effects of Coulomb interaction on the proton halo formation, it finds that the energy level shift has a larger contribution than that of the Coulomb barrier when the mass number A is small, the hindrance of the Coulomb barrier becomes more obvious with the increase of the mass number A, and the overall effect of the Coulomb interaction almost disappears when A ≈ 39 as its two effects counteract with each other.展开更多
The two-dimensional diffusion of interstitial hydrogen atoms in zirconium in a non-uniform stress field was simulated using the phase-field method. The interaction between hydrogen interstitials and the stress field w...The two-dimensional diffusion of interstitial hydrogen atoms in zirconium in a non-uniform stress field was simulated using the phase-field method. The interaction between hydrogen interstitials and the stress field was described by Khachaturyan＇s elastic theory. The Cahn-Hilliard diffusion equation was then solved by an explicit finite difference method. The result shows that hydrogen atoms diffuse to the high-tensile hydrostatic region near the tip of the notch. The content of hydrogen near the tip of the notch increases by 13%, while the stress distribution caused by hydrogen interstitials around the notch is modified by only 0.7%.展开更多
We calculate the exciton binding energy and interband optical absorption in a rectangular coupled quantum wire under the hydrostatic pressure in the effective-mass approximation, using the variational approach. It is ...We calculate the exciton binding energy and interband optical absorption in a rectangular coupled quantum wire under the hydrostatic pressure in the effective-mass approximation, using the variational approach. It is found that the interband optical absorption strongly depend on the hydrostatic pressure and the coupling parameter, and that the magnitude of the absorption coefficient for the HH1-E1 transition in the coupled quantum wire is larger than that of the single quantum wire.展开更多
The strain distribution and electronic structures of the InAs/GaAs quantum ring molecule are calculated via the finite element method.In our model,three identical InAs quantum rings are aligned vertically and embedded...The strain distribution and electronic structures of the InAs/GaAs quantum ring molecule are calculated via the finite element method.In our model,three identical InAs quantum rings are aligned vertically and embedded in the cubic GaAs barrier.Considering the band edge modification induced by the strain,the electronic ground state and the dependence of ground state energy on geometric parameters of the quantum ring molecule are investigated.The change of localization of the wavefunction resulting from the applied electric field along the growth direction is observed.The ground state energy decreases as the electric field intensity increases in a parabolic-like mode.The electric field changes the monotonic dependence of the energy level on the inter-ring distance into a non-monotonic one.However,the electric field has no effect on the relationships between the energy level and other geometric parameters such as the inner radius and outer radius.展开更多
基金Project supported by the Education Bureau Key Natural Science Foundation of Jiangsu Province （Grant No 03KJA140117） and by the 0pen Foundation of Jiangsu Key Laboratory of Thin Film （Grant No K2022）.
文摘This paper studies the critical behaviours and magnetic properties of three-dimensional bond and anisotropy dilution Blume-Capel model （BCM） in the presence of an applied field within the effective field theory. The trajectory of tricritical point, reentrant transitions and degenerate patterns of anisotropy are obtained both for the bond and the anisotropy dilutions. The global phase diagrams demonstrate unusually reentrant phenomena. The temperature dependences of magnetization curves undergo remarkable spin glass behaviour at low temperatures, and transform from ferromagnetism to paramagnetism at high temperature in applied fields. Temperature dependence of magnetic susceptibility curve is in qualitative agreement with experimental result.
基金Supported by the National Natural Science Foundation of China under Grant Nos U1332143 and 11574323
文摘HgCr2S4 is a typical compound manifesting competing ferromagnetic （FM） and antiferromagnetic （AFM） exchanges as well as strong spin-lattice coupling. Here we study these effects by intentionally choosing a combination of magnetization under external hydrostatic pressure and thermal conductivity at various magnetic fields. Upon applying pressure up to 10 kbar at 1 kOe, while the magnitude of magnetization reduces progressively, the AFM ordering temperature TN enhances concomitantly at a rate of about 1.5 K/kbar. Strikingly, at lO kOe the field polarized FM state is found to be driven readily back to an AFM one even at only 5kbar. In addition, the thermal conductivity exhibits drastic increments at various fields in the temperature range with strong spin fluctuations, reaching about 30% at 50 kOe. Consequently, the results give new experimental evidence of spin-lattice coupling. Apart from the colossal magnetoeapacitance and colossal magnetoresistance reported previously, the findings here may enable new promising functionalities for potential applications.
基金Project supported by the China Postdoctoral Science Foundation(No.2018M631909)the Doctor of Entrepreneurship and Innovation Project of Jiangsu Province(No.JSSCBS20221300)。
文摘In this paper,we focus on the two-dimensional pulsating nanofluid flow through a parallel-plate channel in the presence of a magnetic field.The pulsating flow is produced by an applied pressure gradient that fluctuates with a small amplitude.A kind of proper transformation is used so that the governing equations describing the momentum and thermal energy are reduced to a set of non-dimensional equations.The analytical expressions of the pulsating velocity,temperature,and Nusselt number of nanofluids are obtained by the perturbation technique.In the present study,the effects of the Cu-H2O and Al_(2)O_(3)-H2O nanofluids on the flow and heat transfer in pulsating flow are compared and analyzed.The results show that the convective heat transfer effect of Cu-H2O nanofluids is better than that of Al_(2)O_(3)-H2O nanofluids.Also,the effects of the Hartmann number and pulsation amplitude on the velocity,temperature,and Nusselt number are examined and discussed in detail.The present work indicates that increasing the Hartmann number and pulsation amplitude can enhance the heat transfer of the pulsating flow.In addition,selecting an optimal pulsation frequency can maximize the convective heat transfer of the pulsating flow.Therefore,improved understanding of these fundamental mechanisms is conducive to the optimal design of thermal systems.
文摘It is well known that the critical current density of a superconductor depends on its size, shape, nature of doping and the manner of preparation. It is suggested here that the collective effect of such differences for different samples of the same superconductor is to endow them with different values of the Fermi energy—a single property to which may be attributed the observed variation in their critical current densities. The study reported here extends our earlier work concerned with the generalized BCS equations [Malik, G.P. (2010) Physica B, 405, 3475-3481;Malik, G.P. (2013) WJCMP, 3,103-110]. We develop here for the first time a framework of microscopic equations that incorporates all of the following parameters of a superconductor: temperature, momentum of Cooper pairs, Fermi energy, applied magnetic field and critical current density. As an application of this framework, we address the different values of critical current densities of Bi-2212 for non-zero values of temperature and applied magnetic field that have been reported in the literature.
文摘The superexchange interaction on a magnetic ion may be represented by an effective field Hm =λM in some paramagnetic materials, here λis the coefficient of effective field and M = XHe with X being the magnetic susceptibility and He being the applied field. The variation of the equivalent λX with the dynamic applied field is given and the crystal field-splitting levels of the excited configuration 4f75d1 of the Tb3＋ ion are calculated in the Tb3Ga5O12. By means of the effective field Hm and the applied field He, the Faraday rotation of Tb3CasO12 at 6 K and 41 K, under the high magnetic field and at 0.63μm wavelength, are presented. Our calculated results are in agreement with the experimental data.
基金the National Natural Science Foundation of China (No 50235030 and No 50505052)
文摘To investigate the influence of stress alone on the stray field signals of ferromagnetic materials,the static tensile tests of 0.45%C steel and 45CrNiMoVA steel flat-shaped specimens were performed on an MTS810 hydraulic testing machine. Hp（y） signals,the normal component of spontaneous stray field,were measured during the testing process by an EMS-2003 metal magnetic memory diagnostic apparatus cooperated with a non-magnetic electric control displacement instrument. Fracture and microstructure were observed by a scanning electronic microscope and a transmission electron microscope,respectively. The relationships between axial applied stress or residual stress measured by X-ray diffraction method and Hp（y） were analyzed. The results indicate that some regular pattern of the magnetic curve is displayed only between applied stress and stray field signals. The magnetic ordering process stops due to dislocation pinning magnetic domain structure,and Hp（y） value unvaried nearly with applied load increasing in the plastic deformation stage.
基金Project supported by the National Natural Science Foundation of China(Grant No.52072132)。
文摘Adsorption characteristics of CO adsorbed on pristine 4,12,2-graphyne(4,12,2-G)and Fe-doped 4,12,2-graphyne(Fe-4,12,2-G)are studied by first-principles calculations.It is shown that CO is only physically adsorbed on pristine 4,12,2-G.Fe atoms can be doped into 4,12,2-G stably and lead to band gap opening.After doping,the interaction between Fe-4,12,2-G and CO is significantly enhanced and chemisorption occurs.The maximum adsorption energy reaches-1.606 e V.Meanwhile,the charge transfer between them increases from 0.009e to 0.196e.Moreover,the electric field can effectively regulate the adsorption ability of the Fe-4,12,2-G system,which is expected to achieve the capture and release of CO.Our study is helpful to promote applications of two-dimensional carbon materials in gas sensing and to provide new ideas for reversible CO sensor research.
文摘In the present study, kambala (botanical name: Chlorophora excelsa and Chlorophora regia) wood wastes were incorporated into stabilized earth bricks in order to test their acoustic insulation capacity of the walls;leading to better waste management from the timber industry. Two methods have been applied to determine the influence of the wood waste content in the stabilized earth bricks, on the weakening of the level of noise reception coming from the environmental medium, in an apartment built with composite bricks (earth + wood chips + cement). This influence has also been analyzed on the magnetic field induced by these bricks. The results showed that the level of sound reception through these bricks decreases with increasing wood waste content regardless of the method used (from 110 dB to 68 dB, respectively for Φb = 0% and Φb = 8%). The kambala wood waste in cement-stabilized clay bricks induces a magnetic field that increases with the wood waste content;the high contents of the wood chips causing an increase in the magnetic permeability of the composite medium. The correlation between the noise level and the magnetic field of the bricks shows that the noise level declines with increasing magnetic induction of the bricks.
基金Supported by the National Natural Science Foundation of China under Grant No 11175088
文摘We utilize the effective field theory approach to study the properties of the axion. In particular, with s as well as u and d quarks regarded to be relatively light we derive a formula for the mass of the axion; a rough estimate of the rate for its dominant decay mode at low energy is also carried out.
文摘The paper is based on the development of a wood preservative without metal salts to be used in use classes 3 and 4 (EN 335), eco-friendly and harmless to humans and animals. Boric acid was used as a biocide, due to its effectiveness against fungi and insects. It is also known to be easily leached from wood exposed to weather action. Colloidal silica was therefore added in the formulations to guarantee the fixation of boric acid to wood. The different formulations were tested for the protective efficacy against decay fungi through laboratory tests (EN 113) and field trials (EN 252). The results were promising, especially those concerning boron fixation and efficacy against decay fungi through laboratory tests, where some formulations and retentions gave a durability class 1 (very durable) according to EN 350-1. The fourth evaluation, after 50 months of field trials showed only a slight difference between the treated samples and controls.
文摘Motion is a ground-laying concept in physics. Its meaning however depends fundamentally on the assumptions about the nature of empty space. In Einstein’s theory of relativity (TR), no absolute references can be defined and only relative motions are relevant. This however makes it impossible to understand why the motion of matter obeys the principle of inertia and why there exist laws of motion. The Higgs theory introduces radical changes in the current view about the nature of empty space. It introduces the idea that space is filled up by a real and very powerful quantum fluid medium, giving mass to the elementary particles by the Higgs mechanism. This Higgs Quantum Space (HQS) is locally an absolute reference for rest and for motions. It not only recovers an intrinsic meaning for motions, however literally governs the inertial motion of matter-energy. In this new scenario, the velocity of light is fixed with respect to the local HQS and velocity of matter with respect to the local HQS and not relative velocities are responsible for all the effects of motion. The Higgs mechanism is too responsible for the gravitational dynamics;because it is mass that creates the gravitational fields. Actually several clear experimental observations demonstrate that the HQS is moving round the sun consistently with the planetary motions. The present work therefore replaces Einstein’s spacetime curvature by a Keplerian velocity field of the HQS. This velocity field creates the ingenious outside-inside centrifuge mechanism of gravity. It also causes all the observed effects of the gravitational fields on light and on clocks.
文摘The empirically reported values of the critical current density (<i>j<sub>c</sub></i>) of Bi-2212 as 2.4 × 10<sup>5</sup> (<i>j<sub>c</sub></i><sub>1</sub>;Sample 1) and 1.0 × 10<sup>6</sup> A/cm<sup>2</sup> (<i>j<sub>c</sub></i><sub>2</sub>;Sample 2) are intriguing because both of them correspond to the <i>same</i> values of the temperature <i>T</i> = 4.2 K and the applied magnetic field <i>H</i> = 12 × 10<sup>4</sup> G. This difference is conventionally attributed to such factors—not all of which are quantifiable—as the geometry, dimensions and the nature of dopants and the manners of preparation of the samples which cause their granular structures, grain boundaries, alignment of the grains and so on to differ. Based on the premise that the chemical potential <i>μ</i> subsumes most of these features, given herein is a novel explanation of the said results in terms of the values of <i>μ</i> of the two samples. This paper revisits the problem that was originally addressed in [Malik G.P., Varma V.S. (2020) WJCMP, 10, 53-70] in the more accurate framework of a subsequent paper [Malik G.P., Varma V.S. (2021) JSNM, 34, 1551-1561]. Besides, it distinguishes between the contributions of the electro-electron (<i>e-e</i>) and the hole-hole (<i>h-h</i>) pairs to <i>j<sub>c</sub></i>—a feature to which no heed was paid earlier. The essence of our findings is that the <i>j<sub>c</sub></i>s of the two samples differ because they are characterized by different values of the <i>primary</i> variables <i>μ<sub>i</sub></i><sub> </sub>and <img src="Edit_e1b831e9-dc51-4c3b-bd84-fa905e3e62b5.png" alt="" />, where <img src="Edit_1f775a80-30ab-447d-861f-afb4ba8fba6a.png" alt="" /> is the effective mass of a charge-carrier and <i>m<sub>e</sub></i><sub> </sub>is the free-electron mass and <i>i</i> = 1 and 2 denote Sample 1 and Sample 2, respectively. In the scenario of the charge-carriers being <i>predominantly h-h</i> pairs, the values of these parameters are estimated to be: <i>μ</i><sub>1</sub> ≈ 12.3 meV, <i>η</i><sub>1</sub> ≈ 0.58;<i>μ</i><sub>2</sub> ≈ 22.7 meV, <i>η</i><sub>2</sub> ≈ 0.94. Following from these and similar estimates when the charge-carriers are <i>e-e</i> pairs, given below for each sample are the detailed results for the values of the <i>secondary</i> variables viz. the number density of the charge-carriers and their critical velocity, the number of occupied Landau levels and the magnetic interaction parameter.
基金supported by Molecular Technology Research Unit, Walailak University and Department of Physics, Kasetsart University
文摘Magnetic properties of composites prepared by coating lacquer containing neodymium iron boron （Nd-Fe-B） powders on rubberwood were characterized by vibrating sample magnetometry （VSM）, magnetic moment measurements, and attraction tests with an iron-core solenoid. The Nd-Fe-B powders were recycled from electronic wastes by the ball-milling technique. Varying the milling time from 20 to 300 min, the magnetic squareness and the coercive field of the Nd-Fe-B powders were at the minimum when the powders were milled for 130 rain. It followed that the coercive field of the magnetic wood composites was increased with the milling time increasing from 130 to 300 min. For the magnetic wood composites using Nd-Fe-B obtained from the same milling time, the magnetic squareness and the coercive field were rather insensitive to the variation of Nd-Fe-B concentration in coating lacquer from 0.43 to 1.00 g/cm3. By contrast, the magnetization and magnetic moment were increased with the Nd-Fe-B concentration increasing. Furthermore, the electrical current in the solenoid required for the attraction of the magnetic wood composites was exponentially reduced with the increase in the amount of Nd-Fe-B used in the coating.
文摘A double cascade-type four-level multiple-quantum-well-based exciton-biexciton transitions are proposed. The study is carried out on a 4.8-rim ZnSe single-quantum well which is embedded into ZnMgSSe cladding layers and pseudomor- phically grown by molecular beam epitaxy on a （0 0 1） GaAs substrate. It is displayed that the exciton spin relaxation and relative phases between applied fields can influence the transient and steady-state behaviors of absorption, dispersion, and group velocity of two weak probe and signal fields. Also, transient behaviors of electron population of different levels are discussed. It is found that the probe or signal amplification occurs in the absence of population inversion.
基金Project supported by the National Natural Science Foundation of China (Grant No 10435020)the Science Foundation of the Beijing Education Committee (Grant No XK100270454)
文摘This paper makes some qualitative and quantitative analyses about halo formation rules of some mirror nuclei with the relativistic mean-field （RMF） theory and the Woods Saxon mean-field model. By analysing two opposite effects of Coulomb interaction on the proton halo formation, it finds that the energy level shift has a larger contribution than that of the Coulomb barrier when the mass number A is small, the hindrance of the Coulomb barrier becomes more obvious with the increase of the mass number A, and the overall effect of the Coulomb interaction almost disappears when A ≈ 39 as its two effects counteract with each other.
基金This work was financially supported by the National Natural Science Foundation of China (No.50428101), the Research GrantsCouncil of Hong Kong (B-Q471), the Hong Kong Polytechnic University (G-V851), and the U.S. National Science Foundation (DMR96-33719)
文摘The two-dimensional diffusion of interstitial hydrogen atoms in zirconium in a non-uniform stress field was simulated using the phase-field method. The interaction between hydrogen interstitials and the stress field was described by Khachaturyan＇s elastic theory. The Cahn-Hilliard diffusion equation was then solved by an explicit finite difference method. The result shows that hydrogen atoms diffuse to the high-tensile hydrostatic region near the tip of the notch. The content of hydrogen near the tip of the notch increases by 13%, while the stress distribution caused by hydrogen interstitials around the notch is modified by only 0.7%.
文摘We calculate the exciton binding energy and interband optical absorption in a rectangular coupled quantum wire under the hydrostatic pressure in the effective-mass approximation, using the variational approach. It is found that the interband optical absorption strongly depend on the hydrostatic pressure and the coupling parameter, and that the magnitude of the absorption coefficient for the HH1-E1 transition in the coupled quantum wire is larger than that of the single quantum wire.
基金supported by the National High Technology Research and Development Program of China (Grant No 2009AA03Z405)the National Natural Science Foundation of China (Grant Nos 60908028 and 60971068)the High School Innovation and Introducing Talent Project of China (Grant No B07005)
文摘The strain distribution and electronic structures of the InAs/GaAs quantum ring molecule are calculated via the finite element method.In our model,three identical InAs quantum rings are aligned vertically and embedded in the cubic GaAs barrier.Considering the band edge modification induced by the strain,the electronic ground state and the dependence of ground state energy on geometric parameters of the quantum ring molecule are investigated.The change of localization of the wavefunction resulting from the applied electric field along the growth direction is observed.The ground state energy decreases as the electric field intensity increases in a parabolic-like mode.The electric field changes the monotonic dependence of the energy level on the inter-ring distance into a non-monotonic one.However,the electric field has no effect on the relationships between the energy level and other geometric parameters such as the inner radius and outer radius.
