In this study,the open-source software MFIX-DEM simulations of a bubbling fluidized bed(BFB)are applied to assess nine drag models according to experimental and direct numerical simulation(DNS)results.The influence of...In this study,the open-source software MFIX-DEM simulations of a bubbling fluidized bed(BFB)are applied to assess nine drag models according to experimental and direct numerical simulation(DNS)results.The influence of superficial gas velocity on gas–solid flow is also examined.The results show that according to the distribution of time-averaged particle axial velocity in y direction,except for Wen–Yu and Tenneti–Garg–Subramaniam(TGS),other drag models are consistent with the experimental and DNS results.For the TGS drag model,the layer-by-layer movement of particles is observed,which indicates the particle velocity is not correctly predicted.The time domain and frequency domain analysis results of pressure drop of each drag model are similar.It is recommended to use the drag model derived from DNS or fine grid computational fluid dynamics–discrete element method(CFD-DEM)data first for CFD-DEM simulations.For the investigated BFB,the superficial gas velocity less than 0.9 m·s^(-1) should be adopted to obtain normal hydrodynamics.展开更多
Structural and optical properties of nanometric titanium oxide(TixOy) films obtained by cathodic arc plasma deposition were investigated. Phase analysis by x-ray diffraction and Fouriertransform infrared spectroscop...Structural and optical properties of nanometric titanium oxide(TixOy) films obtained by cathodic arc plasma deposition were investigated. Phase analysis by x-ray diffraction and Fouriertransform infrared spectroscopy showed the presence of anatase, rutile, Ti_2O_3, Ti_4O_7 and amorphous phases. Scanning electron microscopy images showed well-developed surface morphology with nano-patterns. Spectroscopic ellipsometry revealed film thicknesses of 53 and50 nm, variable refractive indices dependent on the light wavelength and close to zero extinction coefficients for wavelengths higher than 500 nm. On the basis of ultraviolet–visible spectroscopy data and using the Tauc equation, band gap values for direct and indirect electron transitions were determined.展开更多
We investigate the interactions of charged particles with straight and bent single-walled carbon nanotubes (SWNTs) under channeling conditions in the presence of dynamic polarization of the valence electrons in carb...We investigate the interactions of charged particles with straight and bent single-walled carbon nanotubes (SWNTs) under channeling conditions in the presence of dynamic polarization of the valence electrons in carbon, This polarization is described by a cylindrical, two-fluid hydrodynamic model with the parameters taken from the recent modelling of several independent experiments on electron energy loss spectroscopy of carbon nano-structures. We use the hydrodynamic model to calculate the image potential for protons moving through four types of SWNTs at a speed of 3 atomic units. The image potential is then combined with the Doyle-Turner atomic potential to obtain the total potential in the bent carbon nanotubes. Using that potential, we also compute the spatial and angular distributions of protons channeled through the bent carbon nanotubes, and compare the results with the distributions obtained without taking into account the image potential.展开更多
Particles and fields represent two major modeling paradigms in pure and applied science at all. In this paper a methodology and some of the results for three-dimensional (3D) simulations that include both field and pa...Particles and fields represent two major modeling paradigms in pure and applied science at all. In this paper a methodology and some of the results for three-dimensional (3D) simulations that include both field and particle abstractions are presented. Electromagnetic field calculations used here are based on the discrete differential form representation of the finite elements method, while the Monte Carlo method makes foundation of the particle part of the simulations. The first example is the simulation of the feature profile evolution during SiO2 etching enhanced by Ar + /CF4 non-equilibrium plasma based on the sparse field method for solving level set equations. Second example is devoted to the design of a spiral inflector which is one of the key devices of the axial injection system of the VINCY Cyclotron.展开更多
Properties of an operator representing the dynamical time in the extended parameterization invariant formulation of quantum mechanics are studied. It is shown that this time operator is given by a positive operator me...Properties of an operator representing the dynamical time in the extended parameterization invariant formulation of quantum mechanics are studied. It is shown that this time operator is given by a positive operator measure analogously to the quantities that are known to represent various measurable time operators. The relation between the dynamical time of the extended formulation and the best known example of the system time operator, i.e., for the free one- dimensional particle, is obtained.展开更多
Pure and Pt-doped ZnO nanophase particles were synthesized using the ultrasonic spray pyrolysis. Particles were obtained through decomposition of zinc nitrate and new developed Pt(IV) complex with 1,3-propylenediami...Pure and Pt-doped ZnO nanophase particles were synthesized using the ultrasonic spray pyrolysis. Particles were obtained through decomposition of zinc nitrate and new developed Pt(IV) complex with 1,3-propylenediamine-N,N-diacetate ligand (pdda) belonging to the tetradentate class. The complex is characterized by elemental analysis, electronic absorption and infrared spectra. The crystal structure of trans-[Pt(pdda)Br2]·H2O complex has been determined implying that Pt(IV) ion has a distorted octahedral coordination due to intramolecular N-H ...Br interaction. Ultrasonically derived pure and Pt-doped ZnO particles were characterized by XRD, SEM, EDS and TEM analysis. It was shown that zincite phase exhibits different growing morphologies influenced by precursor chemistry and processing parameters. The composite inner structure, primary particle size and mechanism of Pt 4+ ion introducing into ZnO cell is discussed based on structural refinement and selected area electron diffraction analysis.展开更多
Oxidative stress(OS)occurs when the production of reactive oxygen species(ROS)overrides the body’s natural defence.When the cell nucleus represents the target,macromolecular damage may result in mutations.Cancer is a...Oxidative stress(OS)occurs when the production of reactive oxygen species(ROS)overrides the body’s natural defence.When the cell nucleus represents the target,macromolecular damage may result in mutations.Cancer is a disease of mutations,and DNA damages that are not repaired or mis-repaired during cell proliferation are necessary but not sufficient for cancer development.A role of ROS for cancer initiation depends on the likelihood of interaction between reactive electrophilic molecules and nuclear DNA.As described in part one of this presentation,the physico-chemical properties of the ROS involved in OS and of the ensuing DNA lesions are of major importance.Current knowledge dictates that emphasis should be shifted from oxidative DNA damages of low genotoxicity towards pro-mutagenic lesions induced by reaction products of nitrogen monoxide and complex highly reactive carbonyls,e.g.from the peroxidation of lipids.Based on the determination of pro-mutagenic DNA adducts in human tissues there is compelling evidence for a causal relation between OS and cancers of the liver,colon/rectum,cervix,pancreas and stomach.However,modulation by the simultaneous presence of an ubiquitous high background of potent pro-carcinogenic DNA adducts,which are not generated by ROS should be taken into account.Ionizing radiation is established human carcinogenic agent,and generate some of the same oxidative ROS as those involved in OS.However,the cancer spectrum from whole body radiation exposure differs in some important respects from that associated with OS.The scientific support for a causal link between exposure to non-ionizing electromagnetic radiation and human cancer is judged to be insufficient.As exemplified by diabetes,a common shortcoming when assessing the role of OS in disease is the failure to distinguish between cause and effect-i.e.could the indicators of harmful oxidative stress be the result of the pathological condition in question,rather than its cause.展开更多
Oxidative stress(OS)occurs when the production of reactive oxygen species(ROS)overpowers the body’s natural defence,causing macromolecular damage.The role of OS in cancer initiation will depend on the likelihood of i...Oxidative stress(OS)occurs when the production of reactive oxygen species(ROS)overpowers the body’s natural defence,causing macromolecular damage.The role of OS in cancer initiation will depend on the likelihood of interaction between short lived ROS and nuclear DNA.For this reason,a description of the physico-chemical properties of the various ROS that have been suggested to be involved is included.DNA damages that are not repaired or mis-repaired during cell proliferation are necessary but not sufficient for cancer initiation.The characteristics of DNA pro-mutagenic lesions and their potential role in cancer induction will be assessed,while stressing quantitative aspects as well as the importance of DNA repair.A low level of a specific DNA adduct can be compensated for by its persistence and high pro-mutagenic potency.Because ionizing radiations generate some of the same oxidative ROS as those involved in OS,the cancer spectrum from whole body radiation exposure should be compared with that associated with OS.A causal link between electromagnetic radiations and human cancer lacks adequate scientific support.Current knowledge dictates that emphasis should be shifted from oxidative damages of low genotoxicity towards pro-mutagenic lesions induced by reaction products of nitrogen monoxide and complex highly reactive carbonyls,e.g.from the peroxidation of lipids.A common shortcoming when assessing the role of OS in disease is the failure to distinguish between cause and effect-i.e.could the indicators of harmful OS be the result of the pathological condition in question,rather than its cause?Further,little attention has been paid to exposure in food to some of the same ROS(e.g.reactive carbonyl compounds),as are generated endogenously by OS.Nor have the simultaneous presence of an ubiquitous high background of potent pro-carcinogenic DNA adducts which are not generated by ROS been taken into account.展开更多
The aim of this research was to investigate the luminescent behavior of ultra-small Eu3+-activated phosphate and vanadate nanoparticles in the presence of pesticides.Nanoparticles have an average diameter of approxima...The aim of this research was to investigate the luminescent behavior of ultra-small Eu3+-activated phosphate and vanadate nanoparticles in the presence of pesticides.Nanoparticles have an average diameter of approximately 2 nm with a narrow size distribution.The monazite crystal structure of phosphate-based particles(space group P121/n1)and single tetragonal zircon-type structure of vanadate-based particles(space group of I41/amd)have been confirmed using X-ray diffraction measurements.All synthesized Eu3+-activated colloidal nanoparticles show sharp emission peaks in the red spectral region.Photoluminescence measurements revealed emission quenching upon addition of millimolar concentrations of following pesticides:4-Chloro-2-methyl-phenoxyacetic acid(MCPA),2,4-Dichlorophenoxyacetic acid(2,4-D)and N-(phosphonomethyl)glycine(Glyphosate).In both phosphate and vanadate-based colloidal nanoparticles luminescence quenching is more evident in the presence of 2,4-D pesticide with the lowest limit of detection(0.7μM)obtained for phosphate-based nanoparticles.展开更多
We use the Galerkin approach and the finite-element method to numerically solve the effective-mass Schr¨odinger equation.The accuracy of the solution is explored as it varies with the range of the numerical domai...We use the Galerkin approach and the finite-element method to numerically solve the effective-mass Schr¨odinger equation.The accuracy of the solution is explored as it varies with the range of the numerical domain.The model potentials are those of interdiffused semiconductor quantum wells and axially symmetric quantum wires.Also,the model of a linear harmonic oscillator is considered for comparison reasons.It is demonstrated that the absolute error of the electron ground state energy level exhibits a minimum at a certain domain range,which is thus considered to be optimal.This range is found to depend on the number of mesh nodes N approximately as α_0 log_e^(α1)(α_2N),where the values of the constants α_0,α_1,and α_2are determined by fitting the numerical data.And the optimal range is found to be a weak function of the diffusion length.Moreover,it was demonstrated that a domain range adaptation to the optimal value leads to substantial improvement of accuracy of the solution of the Schr¨odinger equation.展开更多
Rectification phenomena and the phase locking in a two-dimensional overdamped Frenkel-Kontorova model with a graphite periodic substrate were studied. The presence of dc and ac forces in the longitudinal direction cau...Rectification phenomena and the phase locking in a two-dimensional overdamped Frenkel-Kontorova model with a graphite periodic substrate were studied. The presence of dc and ac forces in the longitudinal direction causes the appearance of dynamicalmode locking and the steps in the response function of the system. On the other hand, the presence of an ac force in the transverse direction causes the appearance of rectification,even though there is no net dc force in the transverse direction. It is found that whereas the longitudinal velocity increases in a series of steps, rectification in the transverse direction can occur only between two neighbor steps. The amplitude and phase of the external ac driving force affect the depinning force,rectification of the system and particles trajectories.展开更多
Two extensive collaborative meta studies including 13 residential case-control studies from Europe and 7 from North America have demonstrated that domestic radon clearly poses a risk for lung cancer at exposure levels...Two extensive collaborative meta studies including 13 residential case-control studies from Europe and 7 from North America have demonstrated that domestic radon clearly poses a risk for lung cancer at exposure levels approaching those for underground miners.An excess risk for lung cancer of 0.08–0.16 per 100 Bq/m3 increase in radon concentration was obtained,with a positive trend of increased relative risk at above 200 Bq/m3.However,estimation of the cancer risk associated with domestic radon obtained by the pooling of multiple casecontrol studies has led to inaccuracies of the derived risk estimates in the low dose range,mainly due to smoking misclassification bias,uncertainties with respect to radon dosimetry,the histopathological characterization of lung cancers,as well as confounding by co-exposures with tobacco smoke and other indoor air pollutants.Together with a lack of biological plausibility,these deficiencies have a negative impact on the reliability of reported statistical relations between radon exposure and lung cancer at concentrations below 200 Bq/m3.It is vital that costly remedial actions to reduce domestic radon exposure are based on a scientifically robust risk assessment,and in view of aforementioned flaws,the hitherto proposed risk estimates need to be reconsidered.展开更多
The multicore fiber(MCF)is a physical system of high practical importance.In addition to standard exploitation,MCFs may support discrete vortices that carry orbital angular momentum suitable for spatial-division multi...The multicore fiber(MCF)is a physical system of high practical importance.In addition to standard exploitation,MCFs may support discrete vortices that carry orbital angular momentum suitable for spatial-division multiplexing in high-capacity fiber-optic communication systems.These discrete vortices may also be attractive for high-power laser applications.We present the conditions of existence,stability,and coherent propagation of such optical vortices for two practical MCF designs.Through optimization,we found stable discrete vortices that were capable of transferring high coherent power through the MCF.展开更多
Recent LHC results on the appearance of sub-leading flow modes in Pb Pb collisions at 2.76 TeV, related to initial-state fluctuations, are analyzed and interpreted within the HYDJET++ model. Using the newly introduc...Recent LHC results on the appearance of sub-leading flow modes in Pb Pb collisions at 2.76 TeV, related to initial-state fluctuations, are analyzed and interpreted within the HYDJET++ model. Using the newly introduced Principal Component Analysis(PCA) method applied to two-particle azimuthal correlations extracted from the model calculations, the leading and sub-leading flow modes are studied as a function of the transverse momentum(p T) over a wide centrality range. The leading modes of the elliptic(v2^(1)) and triangular(v3^(1)) flow calculated with the HYDJET++ model reproduce rather well the v2 {2} and v3 {2} coefficients measured experimentally using the two-particle correlations. Within the p T 3 Ge V/c range, where hydrodynamics dominates, the sub-leading flow effects are greatest at the highest p T of around 3 Ge V/c. The sub-leading elliptic flow mode(v2^(2)), which corresponds to the n = 2 harmonic, has a small non-zero value and slowly increases from central to peripheral collisions, while the sub-leading triangular flow mode(v3^(2)), which corresponds to the n = 3 harmonic, is even smaller and does not depend on centrality. For n= 2, the relative magnitude of the effect measured with respect to the leading flow mode shows a shallow minimum for semi-central collisions and increases for very central and for peripheral collisions. For the n= 3 case, there is no centrality dependence. The sub-leading flow mode results obtained from the HYDJET++model are in rather good agreement with the experimental measurements of the CMS Collaboration.展开更多
基金the China-CEEC Joint Higher Education Project(Cultivation Project)(CEEC2021001)Srdjan Beloševic,Aleksandar Milicevic and Ivan Tomanovic acknowledge the financial support by the Ministry of Science,Technological Development and Innovation of the Republic of Serbia(Contract Annex:451-03-47/2023-01/200017).
文摘In this study,the open-source software MFIX-DEM simulations of a bubbling fluidized bed(BFB)are applied to assess nine drag models according to experimental and direct numerical simulation(DNS)results.The influence of superficial gas velocity on gas–solid flow is also examined.The results show that according to the distribution of time-averaged particle axial velocity in y direction,except for Wen–Yu and Tenneti–Garg–Subramaniam(TGS),other drag models are consistent with the experimental and DNS results.For the TGS drag model,the layer-by-layer movement of particles is observed,which indicates the particle velocity is not correctly predicted.The time domain and frequency domain analysis results of pressure drop of each drag model are similar.It is recommended to use the drag model derived from DNS or fine grid computational fluid dynamics–discrete element method(CFD-DEM)data first for CFD-DEM simulations.For the investigated BFB,the superficial gas velocity less than 0.9 m·s^(-1) should be adopted to obtain normal hydrodynamics.
基金by the Ministry of Education,Science and Technological Development of the Republic of Serbia(grant 172026)COST action MP1306
文摘Structural and optical properties of nanometric titanium oxide(TixOy) films obtained by cathodic arc plasma deposition were investigated. Phase analysis by x-ray diffraction and Fouriertransform infrared spectroscopy showed the presence of anatase, rutile, Ti_2O_3, Ti_4O_7 and amorphous phases. Scanning electron microscopy images showed well-developed surface morphology with nano-patterns. Spectroscopic ellipsometry revealed film thicknesses of 53 and50 nm, variable refractive indices dependent on the light wavelength and close to zero extinction coefficients for wavelengths higher than 500 nm. On the basis of ultraviolet–visible spectroscopy data and using the Tauc equation, band gap values for direct and indirect electron transitions were determined.
基金supported by the Funds from the Ministry of EducationScience and Technological Development of the Republic of Serbia(Grant No.45005)Natural Sciences and Engineering Research Council of Canada for Finacial Support
文摘We investigate the interactions of charged particles with straight and bent single-walled carbon nanotubes (SWNTs) under channeling conditions in the presence of dynamic polarization of the valence electrons in carbon, This polarization is described by a cylindrical, two-fluid hydrodynamic model with the parameters taken from the recent modelling of several independent experiments on electron energy loss spectroscopy of carbon nano-structures. We use the hydrodynamic model to calculate the image potential for protons moving through four types of SWNTs at a speed of 3 atomic units. The image potential is then combined with the Doyle-Turner atomic potential to obtain the total potential in the bent carbon nanotubes. Using that potential, we also compute the spatial and angular distributions of protons channeled through the bent carbon nanotubes, and compare the results with the distributions obtained without taking into account the image potential.
基金supported by O171037,Ⅲ 41011 and Ⅲ45006 Projects of Ministry of Education and Science,Serbia.
文摘Particles and fields represent two major modeling paradigms in pure and applied science at all. In this paper a methodology and some of the results for three-dimensional (3D) simulations that include both field and particle abstractions are presented. Electromagnetic field calculations used here are based on the discrete differential form representation of the finite elements method, while the Monte Carlo method makes foundation of the particle part of the simulations. The first example is the simulation of the feature profile evolution during SiO2 etching enhanced by Ar + /CF4 non-equilibrium plasma based on the sparse field method for solving level set equations. Second example is devoted to the design of a spiral inflector which is one of the key devices of the axial injection system of the VINCY Cyclotron.
基金Supported by the Ministry of Science and Technological Development of the Republic Serbia and“Super-Intense Laser-Matter Interactions”-SILMI Project,European Scientific Foundation
基金supported by the Ministry of Education, Science and Technological Development of the Republic of Serbia under the research project: “Electrochemical synthesis and characterization of nanostructured functional materials for application in new technologies” (Project No. 172046)
基金The Ministry of Education, Science and Technological Development of the Republic of Serbia has supported financially this work through projects TR 35021 and OI 172005
基金supported by the Ministry of Education, Science and Technological Development of the Republic of Serbia under the research project: “Electrochemical Synthesis and Characterization of Nanostructured Functional Materials for Application in New Technologies” (Project No. 172046)
基金Project supported by the Ministry of Science and Education of the Republic of Serbia (Grant Nos. 171017, 171028, and 171006)
文摘Properties of an operator representing the dynamical time in the extended parameterization invariant formulation of quantum mechanics are studied. It is shown that this time operator is given by a positive operator measure analogously to the quantities that are known to represent various measurable time operators. The relation between the dynamical time of the extended formulation and the best known example of the system time operator, i.e., for the free one- dimensional particle, is obtained.
文摘Pure and Pt-doped ZnO nanophase particles were synthesized using the ultrasonic spray pyrolysis. Particles were obtained through decomposition of zinc nitrate and new developed Pt(IV) complex with 1,3-propylenediamine-N,N-diacetate ligand (pdda) belonging to the tetradentate class. The complex is characterized by elemental analysis, electronic absorption and infrared spectra. The crystal structure of trans-[Pt(pdda)Br2]·H2O complex has been determined implying that Pt(IV) ion has a distorted octahedral coordination due to intramolecular N-H ...Br interaction. Ultrasonically derived pure and Pt-doped ZnO particles were characterized by XRD, SEM, EDS and TEM analysis. It was shown that zincite phase exhibits different growing morphologies influenced by precursor chemistry and processing parameters. The composite inner structure, primary particle size and mechanism of Pt 4+ ion introducing into ZnO cell is discussed based on structural refinement and selected area electron diffraction analysis.
基金The authors would like to thank Professor Jian Tong,School of Public Health,Medical College of Soochow University,Suzhou for his constructive suggestions when preparing this publication.This work was supported by the Suzhou Science and Technology Development Project(SYS2020090)the Program of the Network-type Joint Usage/Research Center for Radiation Disaster Medical Science,the Collaborative Innovation Center of Radiological Medicine of Jiangsu Higher Education Institutions,and a project funded by the Priority Academic Program Development of Jiangsu Higher Education Institutions(PAPD).
文摘Oxidative stress(OS)occurs when the production of reactive oxygen species(ROS)overrides the body’s natural defence.When the cell nucleus represents the target,macromolecular damage may result in mutations.Cancer is a disease of mutations,and DNA damages that are not repaired or mis-repaired during cell proliferation are necessary but not sufficient for cancer development.A role of ROS for cancer initiation depends on the likelihood of interaction between reactive electrophilic molecules and nuclear DNA.As described in part one of this presentation,the physico-chemical properties of the ROS involved in OS and of the ensuing DNA lesions are of major importance.Current knowledge dictates that emphasis should be shifted from oxidative DNA damages of low genotoxicity towards pro-mutagenic lesions induced by reaction products of nitrogen monoxide and complex highly reactive carbonyls,e.g.from the peroxidation of lipids.Based on the determination of pro-mutagenic DNA adducts in human tissues there is compelling evidence for a causal relation between OS and cancers of the liver,colon/rectum,cervix,pancreas and stomach.However,modulation by the simultaneous presence of an ubiquitous high background of potent pro-carcinogenic DNA adducts,which are not generated by ROS should be taken into account.Ionizing radiation is established human carcinogenic agent,and generate some of the same oxidative ROS as those involved in OS.However,the cancer spectrum from whole body radiation exposure differs in some important respects from that associated with OS.The scientific support for a causal link between exposure to non-ionizing electromagnetic radiation and human cancer is judged to be insufficient.As exemplified by diabetes,a common shortcoming when assessing the role of OS in disease is the failure to distinguish between cause and effect-i.e.could the indicators of harmful oxidative stress be the result of the pathological condition in question,rather than its cause.
基金The authors would like to thank Professor Jian Tong,School of Public Health,Medical College of Soochow University,Suzhou for his constructive suggestions when preparing this paper.This work was supported by the Program of the Network-type Joint Usage/Research Center for Radiation Disaster Medical Science。
文摘Oxidative stress(OS)occurs when the production of reactive oxygen species(ROS)overpowers the body’s natural defence,causing macromolecular damage.The role of OS in cancer initiation will depend on the likelihood of interaction between short lived ROS and nuclear DNA.For this reason,a description of the physico-chemical properties of the various ROS that have been suggested to be involved is included.DNA damages that are not repaired or mis-repaired during cell proliferation are necessary but not sufficient for cancer initiation.The characteristics of DNA pro-mutagenic lesions and their potential role in cancer induction will be assessed,while stressing quantitative aspects as well as the importance of DNA repair.A low level of a specific DNA adduct can be compensated for by its persistence and high pro-mutagenic potency.Because ionizing radiations generate some of the same oxidative ROS as those involved in OS,the cancer spectrum from whole body radiation exposure should be compared with that associated with OS.A causal link between electromagnetic radiations and human cancer lacks adequate scientific support.Current knowledge dictates that emphasis should be shifted from oxidative damages of low genotoxicity towards pro-mutagenic lesions induced by reaction products of nitrogen monoxide and complex highly reactive carbonyls,e.g.from the peroxidation of lipids.A common shortcoming when assessing the role of OS in disease is the failure to distinguish between cause and effect-i.e.could the indicators of harmful OS be the result of the pathological condition in question,rather than its cause?Further,little attention has been paid to exposure in food to some of the same ROS(e.g.reactive carbonyl compounds),as are generated endogenously by OS.Nor have the simultaneous presence of an ubiquitous high background of potent pro-carcinogenic DNA adducts which are not generated by ROS been taken into account.
基金support from the National Recruitment Program of High-end Foreign Experts(Grant No.GDT20185200479)offered by the Chongqing University of Posts and Telecommunications(CQUPT),Chinafinancial support of the Ministry of Education,Science and Technological Development of the Republic of Serbia(Nos.45020 and 172056).
文摘The aim of this research was to investigate the luminescent behavior of ultra-small Eu3+-activated phosphate and vanadate nanoparticles in the presence of pesticides.Nanoparticles have an average diameter of approximately 2 nm with a narrow size distribution.The monazite crystal structure of phosphate-based particles(space group P121/n1)and single tetragonal zircon-type structure of vanadate-based particles(space group of I41/amd)have been confirmed using X-ray diffraction measurements.All synthesized Eu3+-activated colloidal nanoparticles show sharp emission peaks in the red spectral region.Photoluminescence measurements revealed emission quenching upon addition of millimolar concentrations of following pesticides:4-Chloro-2-methyl-phenoxyacetic acid(MCPA),2,4-Dichlorophenoxyacetic acid(2,4-D)and N-(phosphonomethyl)glycine(Glyphosate).In both phosphate and vanadate-based colloidal nanoparticles luminescence quenching is more evident in the presence of 2,4-D pesticide with the lowest limit of detection(0.7μM)obtained for phosphate-based nanoparticles.
基金Supported by the Ministry of Education,Science,and Technological Development of Serbia and the Flemish fund for Scientific Research(FWO Vlaanderen)
文摘We use the Galerkin approach and the finite-element method to numerically solve the effective-mass Schr¨odinger equation.The accuracy of the solution is explored as it varies with the range of the numerical domain.The model potentials are those of interdiffused semiconductor quantum wells and axially symmetric quantum wires.Also,the model of a linear harmonic oscillator is considered for comparison reasons.It is demonstrated that the absolute error of the electron ground state energy level exhibits a minimum at a certain domain range,which is thus considered to be optimal.This range is found to depend on the number of mesh nodes N approximately as α_0 log_e^(α1)(α_2N),where the values of the constants α_0,α_1,and α_2are determined by fitting the numerical data.And the optimal range is found to be a weak function of the diffusion length.Moreover,it was demonstrated that a domain range adaptation to the optimal value leads to substantial improvement of accuracy of the solution of the Schr¨odinger equation.
文摘Rectification phenomena and the phase locking in a two-dimensional overdamped Frenkel-Kontorova model with a graphite periodic substrate were studied. The presence of dc and ac forces in the longitudinal direction causes the appearance of dynamicalmode locking and the steps in the response function of the system. On the other hand, the presence of an ac force in the transverse direction causes the appearance of rectification,even though there is no net dc force in the transverse direction. It is found that whereas the longitudinal velocity increases in a series of steps, rectification in the transverse direction can occur only between two neighbor steps. The amplitude and phase of the external ac driving force affect the depinning force,rectification of the system and particles trajectories.
文摘Two extensive collaborative meta studies including 13 residential case-control studies from Europe and 7 from North America have demonstrated that domestic radon clearly poses a risk for lung cancer at exposure levels approaching those for underground miners.An excess risk for lung cancer of 0.08–0.16 per 100 Bq/m3 increase in radon concentration was obtained,with a positive trend of increased relative risk at above 200 Bq/m3.However,estimation of the cancer risk associated with domestic radon obtained by the pooling of multiple casecontrol studies has led to inaccuracies of the derived risk estimates in the low dose range,mainly due to smoking misclassification bias,uncertainties with respect to radon dosimetry,the histopathological characterization of lung cancers,as well as confounding by co-exposures with tobacco smoke and other indoor air pollutants.Together with a lack of biological plausibility,these deficiencies have a negative impact on the reliability of reported statistical relations between radon exposure and lung cancer at concentrations below 200 Bq/m3.It is vital that costly remedial actions to reduce domestic radon exposure are based on a scientifically robust risk assessment,and in view of aforementioned flaws,the hitherto proposed risk estimates need to be reconsidered.
基金We acknowledge the financial support of the Engineering and Physical Sciences Research Council(project UNLOC),a grant from the Ministry of Education and Science of the Russian Federation(Agreement No.14.B25.31.0003)the Ministry of Education,Science and Technology Development,Serbia(Project III45010)The work was partly performed under the auspices of the U.S.Department of Energy at the Lawrence Livermore National Laboratory under Contract DE-AC52-08NA28752.
文摘The multicore fiber(MCF)is a physical system of high practical importance.In addition to standard exploitation,MCFs may support discrete vortices that carry orbital angular momentum suitable for spatial-division multiplexing in high-capacity fiber-optic communication systems.These discrete vortices may also be attractive for high-power laser applications.We present the conditions of existence,stability,and coherent propagation of such optical vortices for two practical MCF designs.Through optimization,we found stable discrete vortices that were capable of transferring high coherent power through the MCF.
基金support for this work was provided by the Ministry of Education,Science and Technological Development of Republic of Serbia(Project Nos.OI 172056 and Ⅲ 45020).
基金Supported by Ministry of Education,Science and Technological Development of the Republic of Serbia(171019)
文摘Recent LHC results on the appearance of sub-leading flow modes in Pb Pb collisions at 2.76 TeV, related to initial-state fluctuations, are analyzed and interpreted within the HYDJET++ model. Using the newly introduced Principal Component Analysis(PCA) method applied to two-particle azimuthal correlations extracted from the model calculations, the leading and sub-leading flow modes are studied as a function of the transverse momentum(p T) over a wide centrality range. The leading modes of the elliptic(v2^(1)) and triangular(v3^(1)) flow calculated with the HYDJET++ model reproduce rather well the v2 {2} and v3 {2} coefficients measured experimentally using the two-particle correlations. Within the p T 3 Ge V/c range, where hydrodynamics dominates, the sub-leading flow effects are greatest at the highest p T of around 3 Ge V/c. The sub-leading elliptic flow mode(v2^(2)), which corresponds to the n = 2 harmonic, has a small non-zero value and slowly increases from central to peripheral collisions, while the sub-leading triangular flow mode(v3^(2)), which corresponds to the n = 3 harmonic, is even smaller and does not depend on centrality. For n= 2, the relative magnitude of the effect measured with respect to the leading flow mode shows a shallow minimum for semi-central collisions and increases for very central and for peripheral collisions. For the n= 3 case, there is no centrality dependence. The sub-leading flow mode results obtained from the HYDJET++model are in rather good agreement with the experimental measurements of the CMS Collaboration.