Subjects -> MATHEMATICS (Total: 1112 journals)
    - APPLIED MATHEMATICS (90 journals)
    - GEOMETRY AND TOPOLOGY (23 journals)
    - MATHEMATICS (818 journals)
    - MATHEMATICS (GENERAL) (45 journals)
    - NUMERICAL ANALYSIS (25 journals)
    - PROBABILITIES AND MATH STATISTICS (111 journals)

MATHEMATICS (818 journals)            First | 1 2 3 4 5     

Showing 401 - 538 of 538 Journals sorted alphabetically
Journal of Computational Physics : X     Open Access   (Followers: 1)
Journal of Computer Engineering, System and Science (CESS)     Open Access  
Journal of Contemporary Mathematical Analysis     Hybrid Journal  
Journal of Cryptology     Hybrid Journal   (Followers: 5)
Journal of Difference Equations and Applications     Hybrid Journal  
Journal of Differential Equations     Full-text available via subscription   (Followers: 1)
Journal of Discrete Algorithms     Hybrid Journal   (Followers: 4)
Journal of Discrete Mathematics     Open Access   (Followers: 1)
Journal of Dynamics and Differential Equations     Hybrid Journal  
Journal of Engineering Mathematics     Hybrid Journal   (Followers: 2)
Journal of Evolution Equations     Hybrid Journal  
Journal of Experimental Algorithmics     Full-text available via subscription   (Followers: 1)
Journal of Flood Risk Management     Hybrid Journal   (Followers: 14)
Journal of Formalized Reasoning     Open Access   (Followers: 2)
Journal of Function Spaces     Open Access  
Journal of Functional Analysis     Full-text available via subscription   (Followers: 2)
Journal of Geochemical Exploration     Hybrid Journal   (Followers: 1)
Journal of Geological Research     Open Access   (Followers: 1)
Journal of Geovisualization and Spatial Analysis     Hybrid Journal  
Journal of Global Optimization     Hybrid Journal   (Followers: 7)
Journal of Global Research in Mathematical Archives     Open Access   (Followers: 1)
Journal of Group Theory     Hybrid Journal   (Followers: 2)
Journal of Homotopy and Related Structures     Hybrid Journal  
Journal of Honai Math     Open Access  
Journal of Humanistic Mathematics     Open Access   (Followers: 1)
Journal of Hyperbolic Differential Equations     Hybrid Journal  
Journal of Indian Council of Philosophical Research     Hybrid Journal  
Journal of Industrial Mathematics     Open Access   (Followers: 2)
Journal of Inequalities and Applications     Open Access  
Journal of Infrared, Millimeter and Terahertz Waves     Hybrid Journal   (Followers: 2)
Journal of Integrable Systems     Open Access   (Followers: 1)
Journal of K-Theory     Full-text available via subscription  
Journal of Knot Theory and Its Ramifications     Hybrid Journal   (Followers: 1)
Journal of Kufa for Mathematics and Computer     Open Access   (Followers: 1)
Journal of Liquid Chromatography & Related Technologies     Hybrid Journal   (Followers: 7)
Journal of Logical and Algebraic Methods in Programming     Hybrid Journal  
Journal of Manufacturing Systems     Full-text available via subscription   (Followers: 4)
Journal of Mathematical Analysis and Applications     Full-text available via subscription   (Followers: 5)
Journal of mathematical and computational science     Open Access   (Followers: 7)
Journal of Mathematical and Fundamental Sciences     Open Access  
Journal of Mathematical Behavior     Hybrid Journal   (Followers: 3)
Journal of Mathematical Chemistry     Hybrid Journal   (Followers: 3)
Journal of Mathematical Cryptology     Hybrid Journal   (Followers: 1)
Journal of Mathematical Extension     Open Access   (Followers: 3)
Journal of Mathematical Finance     Open Access   (Followers: 9)
Journal of Mathematical Imaging and Vision     Hybrid Journal   (Followers: 6)
Journal of Mathematical Logic     Hybrid Journal   (Followers: 3)
Journal of Mathematical Modelling and Algorithms     Hybrid Journal   (Followers: 1)
Journal of Mathematical Neuroscience     Open Access   (Followers: 10)
Journal of Mathematical Sciences     Hybrid Journal  
Journal of Mathematical Sciences and Applications     Open Access   (Followers: 2)
Journal of Mathematical Sociology     Hybrid Journal   (Followers: 3)
Journal of Mathematics     Open Access  
Journal of Mathematics and Statistics     Open Access   (Followers: 8)
Journal of Mathematics and Statistics Studies     Open Access   (Followers: 4)
Journal of Mathematics and the Arts     Hybrid Journal   (Followers: 2)
Journal of Mathematics Education at Teachers College     Open Access   (Followers: 2)
Journal of Mathematics in Industry     Open Access  
Journal of Mathematics Research     Open Access   (Followers: 6)
Journal of Metallurgy     Open Access   (Followers: 8)
Journal of Modern Mathematics Frontier     Open Access  
Journal of Multidisciplinary Modeling and Optimization     Open Access  
Journal of Multivariate Analysis     Hybrid Journal   (Followers: 13)
Journal of Natural Sciences and Mathematics Research     Open Access  
Journal of Nonlinear Analysis and Optimization : Theory & Applications     Open Access   (Followers: 4)
Journal of Nonlinear Mathematical Physics     Hybrid Journal   (Followers: 1)
Journal of Nonlinear Science     Hybrid Journal   (Followers: 1)
Journal of Numerical Cognition     Open Access   (Followers: 1)
Journal of Numerical Mathematics     Hybrid Journal   (Followers: 2)
Journal of Optimization     Open Access   (Followers: 5)
Journal of Peridynamics and Nonlocal Modeling     Hybrid Journal  
Journal of Problem Solving     Open Access   (Followers: 2)
Journal of Progressive Research in Mathematics     Open Access   (Followers: 5)
Journal of Pseudo-Differential Operators and Applications     Hybrid Journal  
Journal of Pure and Applied Algebra     Full-text available via subscription   (Followers: 4)
Journal of Quantitative Analysis in Sports     Hybrid Journal   (Followers: 9)
Journal of Quantitative Linguistics     Hybrid Journal   (Followers: 6)
Journal of Scientific Computing     Hybrid Journal   (Followers: 18)
Journal of Scientific Research     Open Access  
Journal of Symbolic Computation     Hybrid Journal   (Followers: 1)
Journal of the Australian Mathematical Society     Full-text available via subscription  
Journal of the Egyptian Mathematical Society     Open Access  
Journal of the European Mathematical Society     Full-text available via subscription   (Followers: 1)
Journal of the Indian Mathematical Society     Hybrid Journal   (Followers: 1)
Journal of the Institute of Mathematics of Jussieu     Hybrid Journal  
Journal of the London Mathematical Society     Hybrid Journal   (Followers: 2)
Journal of the Nigerian Mathematical Society     Open Access   (Followers: 1)
Journal of Theoretical and Applied Physics     Open Access   (Followers: 8)
Journal of Topology and Analysis     Hybrid Journal  
Journal of Transport and Supply Chain Management     Open Access   (Followers: 16)
Journal of Turbulence     Hybrid Journal   (Followers: 9)
Journal of Uncertainty Analysis and Applications     Open Access   (Followers: 1)
Journal of Universal Mathematics     Open Access  
Journal of Urban Regeneration & Renewal     Full-text available via subscription   (Followers: 11)
JRAMathEdu : Journal of Research and Advances in Mathematics Education     Open Access   (Followers: 5)
JUMLAHKU : Jurnal Matematika Ilmiah STKIP Muhammadiyah Kuningan     Open Access   (Followers: 3)
JURING (Journal for Research in Mathematics Learning)     Open Access   (Followers: 1)
Jurnal Ilmiah AdMathEdu     Open Access  
Jurnal Matematika     Open Access   (Followers: 1)
Jurnal Matematika Integratif     Open Access  
Jurnal Matematika, Sains, Dan Teknologi     Open Access  
Jurnal Natural     Open Access  
Jurnal Pendidikan Matematika Raflesia     Open Access  
Jurnal Penelitian Pembelajaran Matematika Sekolah     Open Access  
Jurnal Penelitian Sains (JPS)     Open Access  
Jurnal Riset Pendidikan Matematika     Open Access  
Jurnal Sains Matematika dan Statistika     Open Access  
Jurnal Tadris Matematika     Open Access  
Jurnal Teknologi dan Sistem Komputer     Open Access  
Kontinu : Jurnal Penelitian Didaktik Matematika     Open Access   (Followers: 3)
Kreano, Jurnal Matematika Kreatif-Inovatif     Open Access   (Followers: 6)
Le Matematiche     Open Access  
Learning and Teaching Mathematics     Full-text available via subscription   (Followers: 7)
Lettera Matematica     Hybrid Journal  
Lietuvos Matematikos Rinkinys     Open Access   (Followers: 3)
Limits : Journal of Mathematics and Its Applications     Open Access   (Followers: 1)
Linear Algebra and its Applications     Full-text available via subscription   (Followers: 23)
Linear and Multilinear Algebra     Hybrid Journal   (Followers: 8)
Lithuanian Mathematical Journal     Hybrid Journal  
LMS Journal of Computation and Mathematics     Free  
Lobachevskii Journal of Mathematics     Open Access  
Logic and Analysis     Hybrid Journal   (Followers: 1)
Logic Journal of the IGPL     Hybrid Journal   (Followers: 1)
Logica Universalis     Hybrid Journal  
manuscripta mathematica     Hybrid Journal  
MaPan : Jurnal Matematika dan Pembelajaran     Open Access  
Marine Genomics     Hybrid Journal   (Followers: 2)
Matemáticas, Educación y Sociedad     Open Access  
Matematicheskie Zametki     Full-text available via subscription  
Matematika     Open Access  
Matematychni Studii     Open Access  
Mathematica Eterna     Open Access  
Mathematica Scandinavica     Full-text available via subscription   (Followers: 1)
Mathematica Slovaca     Hybrid Journal   (Followers: 1)
Mathematical and Computational Forestry & Natural-Resource Sciences     Free  
Mathematical Communications     Open Access  
Mathematical Computation     Open Access   (Followers: 1)
Mathematical Geosciences     Hybrid Journal   (Followers: 3)
Mathematical Journal of Interdisciplinary Sciences     Open Access   (Followers: 1)
Mathematical Medicine and Biology: A Journal of the IMA     Hybrid Journal   (Followers: 1)
Mathematical Methods in the Applied Sciences     Hybrid Journal   (Followers: 4)
Mathematical Methods of Statistics     Hybrid Journal   (Followers: 4)
Mathematical Modelling and Analysis     Open Access   (Followers: 1)
Mathematical Modelling in Civil Engineering     Open Access   (Followers: 5)
Mathematical Modelling of Natural Phenomena     Full-text available via subscription   (Followers: 1)
Mathematical Models and Methods in Applied Sciences     Hybrid Journal   (Followers: 2)
Mathematical Models in Engineering     Open Access   (Followers: 3)
Mathematical Notes     Hybrid Journal  
Mathematical Proceedings of the Cambridge Philosophical Society     Full-text available via subscription   (Followers: 2)
Mathematical Programming Computation     Hybrid Journal   (Followers: 3)
Mathematical Sciences     Open Access  
Mathematical Social Sciences     Hybrid Journal   (Followers: 1)
Mathematical Theory and Modeling     Open Access   (Followers: 13)
Mathematical Thinking and Learning     Hybrid Journal   (Followers: 3)
Mathematics and Statistics     Open Access   (Followers: 5)
Mathematics Education Forum Chitwan     Open Access   (Followers: 1)
Mathematics Education Journal     Open Access   (Followers: 2)
Mathematics Education Research Journal     Partially Free   (Followers: 18)
Mathematics in Science and Engineering     Full-text available via subscription  
Mathematics of Control, Signals, and Systems (MCSS)     Hybrid Journal   (Followers: 5)
Mathematics of Quantum and Nano Technologies     Open Access  
Mathématiques et sciences humaines     Open Access   (Followers: 6)
Mathematische Annalen     Hybrid Journal   (Followers: 1)
Mathematische Nachrichten     Hybrid Journal   (Followers: 1)
Mathematische Semesterberichte     Hybrid Journal  
Mathematische Zeitschrift     Hybrid Journal   (Followers: 1)
MathLAB Journal     Open Access   (Followers: 5)
MATI : Mathematical Aspects of Topological Indeces     Open Access  
MATICS     Open Access   (Followers: 2)
Matrix Science Mathematic     Open Access   (Followers: 1)
Measurement Science Review     Open Access   (Followers: 3)
Mediterranean Journal of Mathematics     Hybrid Journal  
Memetic Computing     Hybrid Journal  
Mendel : Soft Computing Journal     Open Access  
Metaheuristics     Hybrid Journal  
Metals and Materials International     Hybrid Journal  
Metascience     Hybrid Journal   (Followers: 1)
Metrology and Instruments / Метрологія та прилади     Open Access   (Followers: 1)
Milan Journal of Mathematics     Hybrid Journal  
Mitteilungen der DMV     Hybrid Journal  
MLQ- Mathematical Logic Quarterly     Hybrid Journal   (Followers: 1)
MONA : Matematik- og Naturfagsdidaktik     Hybrid Journal   (Followers: 5)
Monatshefte fur Mathematik     Hybrid Journal  
Moroccan Journal of Pure and Applied Analysis     Open Access   (Followers: 4)
Moscow University Mathematics Bulletin     Hybrid Journal  
MSOR Connections     Open Access   (Followers: 1)
Multiscale Modeling and Simulation     Hybrid Journal   (Followers: 3)
MUST : Journal of Mathematics Education, Science and Technology     Open Access   (Followers: 1)
Nagoya Mathematical Journal     Hybrid Journal  
Nano Research     Hybrid Journal   (Followers: 4)
Nanotechnologies in Russia     Hybrid Journal   (Followers: 1)
Natural Resource Modeling     Hybrid Journal   (Followers: 1)
New Mathematics and Natural Computation     Hybrid Journal  
Nonlinear Analysis : Modelling and Control     Open Access   (Followers: 1)
Nonlinear Analysis : Theory, Methods & Applications     Hybrid Journal   (Followers: 1)
Nonlinear Analysis: Hybrid Systems     Hybrid Journal  
Nonlinear Analysis: Real World Applications     Hybrid Journal   (Followers: 2)
Nonlinear Differential Equations and Applications NoDEA     Hybrid Journal  
Nonlinear Engineering     Open Access  
Nonlinear Oscillations     Hybrid Journal   (Followers: 1)

  First | 1 2 3 4 5     

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Journal Cover
Journal of Theoretical and Applied Physics
Journal Prestige (SJR): 0.207
Citation Impact (citeScore): 1
Number of Followers: 8  

  This is an Open Access Journal Open Access journal
ISSN (Print) 1735-9325 - ISSN (Online) 2251-7235
Published by SpringerOpen Homepage  [261 journals]
  • Optimizing the performance of extended-gate field-effect transistor
           (EGFET) pH sensor by regulating the structural properties of the
           nanostructured porous silicon layer

    • Abstract: Abstract We report the performance of extended-gate field-effect transistor (EGFET) pH sensors based on the properties of nanostructured porous silicon layer (nano PSi). Four different forms of nano PSi layers with different characteristic features are used as a sensor for determining the pH level. The synthesized nano PSi layer was prepared by laser-assisted etching of n-type (100) by using different illumination intensities 15, 30, 45 and 60 mW/cm2 of 530 nm laser wavelength. The structural and morphological properties of nano PSi were investigated through exploring scanning electron microscopy, X-ray diffraction (XRD) and gravimetrical measurements. Nano PSi with pore-like structures of various pore shapes and sizes are as follows: fine circular pores, star full pore, circular pores and rectangular pores; star full pore shape was prepared through varying the laser illumination intensity. The Fourier transform infrared spectroscopy, current–voltage measurements and specific surface area of were employed to describe the density of the hydrogenated dangling bonds (Si–Hx) of the nano PSi layer. The synthesized nano PSi pH sensors were tested and dry out in the pH range from 3 to 11 at room temperature. The performance of nano PSi pH sensors was comparatively analyzed based on the density of (Si–Hx), specific surface area, porosity and layer thickness of nano PSi. Concerning EGFET pH sensor showed noticeably enhanced pH sensitivity and linearity with increasing the density of (Si–Hx) and specific surface area. Higher sensitivity with excellent linearity was obtained for pore-like structures of circular pore shapes when the laser illumination intensity was about 45 mW/cm2.
      PubDate: 2021-02-03
       
  • Mitigation of disruption on IR-T1 tokamak by means of low-energy neutral
           beam injection to control runaway electron generation

    • Abstract: Abstract In a tokamak, the poloidal magnetic field provided by the toroidal plasma current forms an essential part of the magnetic field confining the plasma. However, instabilities of magnetohydrodynamic equilibrium can lead to an uncontrolled sudden loss of plasma current and energy, which is called a disruption. Disruptions are of significant concern to future devices due to the large amount of energy released during the rapid quenching of the plasma. One important consequence of disruption is the generation of significant current carried in multi-MeV runaway electrons that are eventually lost into plasma components. They can damage the tokamak walls and its structure if they are not controlled. Disruption control by neutral beam injection has been performed on IR-T1 to study the effect on runaway electron generated by plasma disruptions. Noble gases are used for injection, pure Hydrogen, Helium and Argon. The use of these non-reactive gases for disruption control ensures they fast removed from the vessel after the termination of a tokamak discharge. A piezo-valve is used for injection which has the precision of 1 ms. The effect of runaway electron generation control during disruption is studied using a comparison between reference disruptive discharge and a discharge into which different impurity species are injected. The data collected can then be used to optimize the performance of these energetic electrons control generated in disruption.
      PubDate: 2020-12-01
       
  • Transcriptional responses following seed priming with cold plasma and
           electromagnetic field in Salvia nemorosa L.

    • Abstract: Abstract This study was conducted to monitor the plant responses to seed priming with electromagnetic fields (0, 4, or 6 mT) or cold plasma (0, 80, or 100 s) in Salvia nemorosa. The cold plasma or electromagnetic field treatments significantly increased shoot fresh weight (49%), root fresh weight (41%), and root length (56%). The results highlighted that seed priming with cold plasma or the electromagnetic field is an effective method to modify seedling growth. The electromagnetic field and plasma treatments upregulated the AREB1 gene (mean = 3.9-fold). Except for the electromagnetic field of 4mT, the other treatments stimulated expressions of the WRKY1 gene by an average of 6.7-fold relative to the control. The cold plasma or electromagnetic field also induced the expression of cinnamoyl-CoA reductases (CCR2) gene (mean = fourfold). These treatments also changed the expression of the rosmarinic acid synthase by an average of sixfold. These findings may improve our knowledge of plant reactions to cold plasma and electromagnetic field for possible functions in seed technology.
      PubDate: 2020-12-01
       
  • Efficacy of Plasma ONE apparatus for disinfection of S. aureus , P.
           aeruginosa and E. coli bacteria from the solid surface

    • Abstract: Abstract Cold atmospheric plasma (CAP) is a cocktail of charged particles with high antibacterial potency. In this study, we evaluated CAP efficacy generated by Plasma ONE, a mobile medical device against common chronic wound pathogens. Two sets of working saline suspensions, i.e. 105 and 103 CFU/ml of each reference strain E. coli, P. aeruginosa and S. aureus, were inoculated on Mueller–Hinton media plates and exposed to CAP for 30, 60, 120, 300 s and incubated for 24 h. The radiating nozzle surface was 3.4 cm. Plasma efficacy evaluation was based on the diameter of attained inactivation area and bacterial decontamination rate within. Plasma ONE device showed high capacity against S. aureus in all time intervals and exposure yielded a gradual time-dependent CFU reduction starting with 99.6% after 30 s in the 105 plates. Comparison between mean area diameters of S. aureus and E. coli of 30 and 120 s indicated a significant area increase (p < 0.05). In contrast, P. aeruginosa appeared more resistant to a longer exposure and the inactivation area was hardly extended following the longest exposure. In both Gram-negative bacteria, CFU reduction plateaued at 30 s in 103 petri dishes, while in 105 groups more than 120-s interval was insufficient for attaining full decontamination; however, treatment for 300 s led to complete eradication. Plasma ONE is effective against most commonly isolated pathogens from wounds, but its further validation requires data concerning efficacy in eradicating biofilms.
      PubDate: 2020-11-25
       
  • Dispersion of nanoparticles into the low birefringent nematic liquid
           crystal: study of optical and electro-optical parameters and its
           applicability towards liquid crystal displays

    • Abstract: Abstract In the present reported work, TiO2 nanoparticles (NPs) are dispersed into the pure nematic liquid crystal (NLC) in three different concentrations. The used NLC consisted of 4′-(trans, trans-4-alkylbicyclohexyl) carbonates and 4′-(4-(trans, trans-4-alkyl)-4-cyanobicyclohexane, which is an optically sensitive material. Optical parameters like photoluminescence and UV absorbance for this material can be tuned by doping of TiO2 NPs. Study of photoluminescence parameter is crucial for liquid crystalline materials. Therefore, optical and electro-optical parameters are measured here for pure and NP-dispersed NLC system. UV absorbance was found to be decreased for the TiO2-dispersed system when compared to pure NLC. Band gap was also calculated by using Tauc plot method, and it is found to be decreased for the NP-dispersed system. Photoluminescence study revealed that PL intensity increases after the dispersion of NPs into the pure NLC. This is the key output of the present reported work. Response time measurement was measured by Optical Switching method, and it is found to be reduced for NP-dispersed system when compared to pure NLC. Contrast ratio of the NP-dispersed system was also found to be increased. Threshold voltage showed that it decreases after the dispersion of NPs into the pure NLC. Enhanced photoluminescence, fast optical response time and high contrast ratio are the promising results of the present reported work because these parameters have many applications in the liquid crystal displays, opto-electronics devices and photonic devices.
      PubDate: 2020-11-24
       
  • On the characteristics and optical properties of Mn-based (MnO 2 ) helical
           conical nanostructure thin films

    • Abstract: Abstract Mn-based helical conical nano-sculptured thin films were fabricated by means of oblique angle deposition method in conjunction with the rotation of sample holder with different speeds at different pitches of each revolution. Atomic force microscopy, field emission scanning electron microscopy and X-ray diffraction (XRD) analyses were used to obtain morphology, nanostructure and crystallography of the samples. Formation of MnO2 film by the proposed method of this work is confirmed by the XRD results. Optical spectra of the films were obtained using s- and p-polarized incident lights at three different incident light angles of 0°, 20° and 30°. Bruggeman homogenization method was employed to obtain spectra for different optical parameters. The observed peaks/oscillations in these spectra are related to the different radii of the deposited sculptured structure with helical conical shape. Results show that by engineering of Mn-based (MnO2) helical conical sculptured thin film the absorption is increased. Hence, by engineering of this type of thin films the absorption increases due to entrapment of light between the elements of the structure (rings) and results in a high broadband absorption.
      PubDate: 2020-11-12
       
  • Two-step preparation and characterization of ZnO Core–Si shell
           coaxial nanorods

    • Abstract: Abstract This study compares and analyzes the key characteristics of the ZnO core–Si shell coaxial nanorod (Si@ZnO NR) heterostructures that were grown on semi-insulating, (100)-oriented Si substrates at Si layer temperatures of 450, 500, 550 and 600 °C for optoelectronic device applications. The Si@ZnO NRs were prepared in two separate stages. Vapor-phase transport produced the ZnO NRs, whereas rapid thermal chemical vapor deposition formed the Si layers. Results obtained from X-ray diffraction, field emission scanning electron microscopy, energy-dispersive X-ray spectroscopy and Raman tests indicate that the ZnO NRs were single crystals with a zincblende configuration. The findings also reveal that the Si layer was polycrystalline in nature, poly-Si, with a würtzite configuration. The present research is beneficial to the optoelectronic devices such as light-emitting diodes, solar cells and photodetectors in the UV–infrared range using the Si@ZnO coaxial nanostructures.
      PubDate: 2020-10-29
       
  • Fabrication and characterization of Mn-implanted GaN layers followed by
           annealing

    • Abstract: Abstract We report the effect of Mn incorporation on the structural and optical properties of GaN grown on a sapphire substrate in a plasma-enhanced molecular-beam epitaxy system followed by Mn ion implantation and annealing. The crystalline quality and phase purity were determined by high-resolution X-ray diffraction (XRD). The XRD results indicated that no macroscopic second phases were present in the Mn-implanted GaN layer after the annealing process. High-resolution transmission microscopy and energy dispersive X-ray spectroscopy revealed that the as-grown GaN epilayer and Mn-implanted GaN layer after annealing were single crystals with a hexagonal wurtzite structure, and they grew with a c-axis orientation perpendicular to the sapphire substrate. The Raman and photoluminescence spectra showed that the Mn-implanted GaN layer fabricated with a Mn ion dose of 5 × 1015 cm−2 followed by annealing at 800 °C for 30 min had higher crystalline quality than the Mn-implanted GaN layers fabricated with Mn ion doses of 5 × 1015 and 2 × 1016 cm−2 followed by annealed at 900 °C for 30 and 80 min.
      PubDate: 2020-10-29
       
  • Bismuth-based metal–organic framework prepared by pulsed laser
           ablation method in liquid

    • Abstract: Abstract Metal organic framework (MOF) is an important class of highly porous hybrid materials with its unique structures and properties. A bismuth-based MOF was prepared by pulsed laser ablation in liquid environment as a physical bottom-up method for the first time. The experiment involved the ablation of a bismuth target in a solvents with the fundamental wavelength of a ns pulsed Nd:YAG laser. Materials include bismuth target for preparation of Bi3+ ion as a connector center, benzene-1,3,5-tricarboxylic acid (BTC) as a bridging ligand, and methanol and dimethylformamide as a solvent. We studied the effects of laser fluence and concentration of BTC in the ablation environment on the properties of bismuth-based MOF structure. The MOF was characterized by Fourier transform infrared spectroscopy for determination of functional groups, Ultraviolet–Visible (UV–Vis) spectrophotometer for evaluation of optical properties, X-ray diffraction for investigation of crystal structure, field emission scanning electron microscope, and transmission electron microscope for presentation of morphology and size of produced nanostructures. Based on the results, laser ablation is a capable, clean, and simple candidate method for synthesizing different kinds of MOF.
      PubDate: 2020-10-20
       
  • Industrial application of apodized gas sensor for on-line and in situ
           measurement of CO and CO 2 concentration

    • Abstract: Abstract The performance of an apodized gas sensor is demonstrated through simultaneous detection of CO and CO2 absorption lines around 1.57 µm in the recuperator channel of a gas-fired industrial furnace at Shahid Montazeri power plant (SMPP) industry. This led to the concentration measurement of targeted molecules as less than ~ 1% and 9.5%, respectively, at atmospheric pressure and 350 °C, indicating close consistency with the reference data reported by SMPP. A minimum detectable absorption of ~ 0.4 × 10−3, corresponding to a detection sensitivity of ~ 4.8 × 10−9 cm−1 Hz−1/2 is measured in this application.
      PubDate: 2020-10-07
       
  • The effects of grounded electrode geometry on RF-driven cold atmospheric
           pressure plasma micro-jet

    • Abstract: Abstract With the argument that two-electrode DBD-like systems are much more operational than single-electrode systems in biomedical applications, targets sensitive to temperature and electric shock, the effects of parameters associated with the geometry of the grounded electrode such as its shape, size, and position it at the output of the atmospheric pressure RF plasma jet in two-electrode systems is investigated. By varying the position of the typical narrow ring grounded electrode on the dielectric tube toward the powered electrode, the ratio of the axial to radial electric field components depend on the externally applied potential to the plasma has been investigated and shown that the axial component of the electric field is maximized at certain position(s) of the grounded electrode. The analysis of the data indicates that there is an inverse relationship between the magnitude of the axial electric field in the plasma channel and the discharge ignition voltage, and a direct relationship with the plasma jet length. It is known that by increasing the width of the ground electrode until the full covering of dielectric, the jet length increases from the dielectric output to the neighborhood near the needle electrode, and reduces the discharge ignition threshold and consequently power consumption of the jet, but increasing its width to greater than the above values does not have a significant effect on jet output. It has also been shown that by tapering the dielectric end and fully covering it with its conical-shaped electrode, the output jet length increases and decreases its width.
      PubDate: 2020-10-06
       
  • Comparative study of behavior of electrical conductivity in KI‒Al 2 O 3
           and KI‒TiO 2 heterostructure composites

    • Abstract: Abstract The present work reports development of binary KI–Al2O3 and KI–TiO2-based nanocomposites using simple solid-state reaction method and is characterized by X-ray diffraction, Fourier-transform infrared spectroscopy, scanning electron microscopy and impedance spectroscopy. The results show the effect of heterogeneously doped Al2O3 and TiO2 on the ionic conductivity of pure KI which is moderately conductive. The results supported the composite development in which the interface layer portrays a significant part in governing the bulk properties of the compound. Improvement in electrical conductivity is seen in the incorporation of Al2O3 and TiO2 dispersoid into the matrix of KI. With temperature, electrical conductivity increased and the activation energies were found to be decreasing. The activation energies for KI–Al2O3 and KI–TiO2 systems were 0.22 eV and 0.21 eV, respectively, in the temperature range 20‒400 °C. Dielectric constant increases with the increase in temperature in the entire temperature range studied attributed to the phenomenon of distortion of electric charges.
      PubDate: 2020-09-28
       
  • Tunable and reversible thermo-plasmonic hot spot imaging for temperature
           confinement

    • Abstract: Abstract In the present study, a novel tunable two-dimensional thermo-plasmonic grating based on gold nanorods was demonstrated by combining the plasmonic properties of the gold nanostructure and the applied external voltage. In this structure, a thin layer of the gold grating was typically deposited on a patterned polydimethylsiloxane substrate using the nanoimprint lithography method. The surface plasmon resonance of the fabricated plasmonic structure was excited by the surface plasmon imaging system based on a high numerical aperture objective lens and the charged coupled device camera. Based on the results, the number of the plasmonic hot spots due to the thermo-plasmonic effect increased by the external voltage, leading to an increase in this effect. Therefore, this reversible and tunable temperature confinement can be used as the controller of each element including cells in a defined micro-position.
      PubDate: 2020-09-18
       
  • Terahertz emission during laser-plasma interaction: effect of electron
           temperature and collisions

    • Abstract: Abstract The electron-neutral collisions in the plasma become crucial with regard to the generation of THz radiation when thermal motion of the electrons is considerable. If we look at the mechanism of THz emission, this is only the movement/oscillations of the electrons which is responsible for the excitation of nonlinear current that generated the THz radiation. The present work aims to disclose the role of thermal motion of the plasma electrons to the resonance condition and the THz emission when two co-propagating super-Gaussian laser beams beat in the plasma. The dynamics of the plasma electrons and subsequent generation of nonlinear current are discussed in greater detail for the emission of THz radiation.
      PubDate: 2020-09-05
       
  • Transmission of electromagnetic waves through a nonlinear over-dense
           plasma slab

    • Abstract: Abstract A study on the transmission of the electromagnetic waves from a structure consisting of an over-dense plasma layer with nonlinear effects is undertaken. The applied nonlinearity is presented due to the series expansion of the polarization in the medium. The nonlinear plasma layer is supposed to be placed between two linear dielectric layers. The transparency conditions are investigated for the p-polarized obliquely incident waves. It is shown that the formation of the surface waves can eventuate to the transmission of the incident waves. This fact has already be seen in the case of the linear over-dense plasma, but, here, it is examined in the presence of the nonlinear effects. To determine the propitious conditions for the surface wave excitation, the exact solutions of the electromagnetic field equations are used in all regions. The transmission, the reflection, and the dissipation rates of the electromagnetic waves from the entire structure are obtained, and the effects of the main parameters on them are discussed.
      PubDate: 2020-08-29
       
  • Fabrication of Au/ZnO/MWCNTs electrode and its characterization for
           electrochemical cholesterol biosensor

    • Abstract: Abstract In this work, a new sensitive enzyme-based electrode for electrochemical cholesterol biosensor was fabricated based on a nanocomposite of Au nanoparticles, ZnO nanoparticles and multi-wall carbon nanotubes (Au/ZnO/MWCNTs). The nanocomposite was prepared by sol–gel method and deposited on FTO substrate by dip coating, followed by cholesterol oxidase (ChOx) enzyme immobilized (ChOx/Au/ZnO/MWCNTs). Structural properties and morphology of the nanocomposite have been studied using X-ray diffraction (XRD) and Field emission scanning electron microscopy (FESEM). The sample was subjected to Fourier transform infrared spectroscopy (FTIR) to determine functional groups. Electrochemical behavior of the electrode was studied by cyclic voltammetry (CV) and differential pulse voltammetry (DPV) techniques as a function of cholesterol concentration. Electrochemical impedance spectroscopy (EIS) was also considered to study of surface modified electrodes. The ChOx/Au/ZnO/MWCNTs electrode has been found to have enhanced electron transfer and display excellent analytical linear performances. The fabricated electrode exhibited low detection limit (0.1 μM), high sensitivity (25.89 μA/μM) evaluated from DPV data in the detection range of 0.1–100 µM and high selectivity in the determination of cholesterol over glucose and uric acid. The application of the ChOx/Au/ZnO/MWCNTs electrode in detection of cholesterol in human serum was also confirmed.
      PubDate: 2020-08-19
       
  • The effects of multiwall carbon nanotubes on the electrical
           characteristics of ZnO-based composites

    • Abstract: Abstract In this experimental work, the effects of multiwall carbon nanotubes (MWCNTs) on electrical characteristics of zinc oxide–MWCNT–high-density polyethylene composite varistors have been investigated. All the samples were made at the temperature of 130 °C and pressure of 60 MPa by the hot-press method. Results show that increasing zinc oxide content in the mixture increases breakdown voltage up to 170 V, where the highest nonlinear coefficient (α ~ 13) corresponds to the samples with 95 wt% of ZnO. Results with regard to the effects of MWCNT as an additive reveal that increasing its content from 1 to 2.5% in the composites, the breakdown voltage decreases to 50 V, but the highest nonlinear coefficient (~ 14) corresponds to the sample with 1.5% of MWCNT content. It is also revealed that, heat treatment of the sample at a constant temperature of 135 °C and different time intervals from 2 to 10 h, the sample with 6 h annealing time shows maximum breakdown voltages (Vb = 140 V) with the highest nonlinear coefficient (~ 14). Investigation of the potential barrier height of samples shows a complete consistency with the breakdown voltage variations. The results have been justified regarding XRD patterns and SEM micrographs of samples.
      PubDate: 2020-08-18
       
  • Enhancement of charge breeding efficiency for rare isotope beam with the
           control of magnetic field profile and electron beam energy in EBIS

    • Abstract: Abstract The magnetic field in the ion trap of electron beam ion source (EBIS) determines the current density of electron beam and thus the depth of trap potential, which affects the charge breeding efficiency to desired charge state. An EBIS charge breeder has been constructed to be used for the Rare Isotope Science Project in Korea. A 6 T superconducting solenoid is used for the trap, and uniform magnetic field is extended with correction coils at the ends. The effect of field uniformity on the electron current density is evaluated using TRAK, and it is shown sizable improvement in the charge breeding efficiency for rare isotope beams can be obtained by elaborate magnetic design. Furthermore, the electron beam energy affects the ionization efficiency. The electron energy is often reduced in the trap for optimal matching with charge striping cross section. However, virtual cathode formation can appear in the process of energy reduction. Maximum beam currents limited by electron energy are studied analytically and by TRAK simulation in the view of improving the charge breeding efficiency.
      PubDate: 2020-08-13
       
  • The effect of mixed electric field on characteristic of ozone generation
           in a DBD plasma source

    • Abstract: Abstract In this paper, we have presented a new power supply structure for ozone generation in a dielectric barrier discharge reactor, so that a high-frequency pulse electric field is applied on the reactor simultaneously with a low-frequency sinusoidal electric field, referred as mixed electric field. In this study, the effect of mixed electric field variation on ozone production efficiency has been investigated and increasing effects on ozone production have been observed when the reactor temperature decreases. This performance has been achieved by modifying the mechanism of electrical discharge and decrease in filamentary discharge in plasma. By examining the spectral lines of atomic emission spectroscopy, the highest peak of the oxygen (O I) spectral lines was observed in the spectrum of the mixed electric field structure. Also by qualitative comparison of the spectral lines, the lowest intensity for the oxygen (O II) spectral lines was observed in this spectrum. Practically, this technique allows us to achieve higher ozone efficiency with less electrical power. Eventually, with the electric field mixing, we were able to achieve a 4.5% efficiency with 7.7 g/h of ozone generation at 2 kW/m2 with 2 L/min injector oxygen. In addition, by electric field mixing, we were able to reduce the reactor temperature from 66 to 41 °C.
      PubDate: 2020-07-19
       
  • Investigating the effect of geometrical asymmetry on conductance and TMR
           ratio in the ZnO rock salt-based MTJ: a DFT study

    • Abstract: Abstract Effects of geometrical asymmetry on spintronic properties of Fe/ZnO/Fe magnetic tunnel junction based on zinc oxide barrier tunnel with rock-salt crystalline structure is studied. Simulations are performed using density functional theory, and substituted layers of C, Mg, Al, Mo, and Ta are used to make geometrically asymmetric structures. The results indicate that this asymmetry has a substantial influence on the properties of the spin-dependent electronic transport, conductance, and the tunneling magneto-resistance (TMR) ratio of the pristine symmetric structure. Additionally, it is shown that geometrical asymmetry results in a sharp decrease in the TMR ratio in one of these junctions and causes a negative TMR ratio in the other four asymmetric structures. Due to the large conductance of the three pristine, C and Al substituted structures in the PA configuration, these structures can be used to generate the current with pure spin for experimental purposes.
      PubDate: 2020-07-09
       
 
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