Chisinau, Moldova
Chisinau, Moldova

The Moldova State University is a university located in Chişinău, Moldova. It was founded in 1946. Wikipedia.


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Nika D.L.,University of California at Riverside | Nika D.L.,Moldova State University | Askerov A.S.,Moldova State University | Balandin A.A.,University of California at Riverside
Nano Letters | Year: 2012

We investigated the thermal conductivity K of graphene ribbons and graphite slabs as the function of their lateral dimensions. Our theoretical model considered the anharmonic three-phonon processes to the second-order and included the angle-dependent phonon scattering from the ribbon edges. It was found that the long mean free path of the long-wavelength acoustic phonons in graphene can lead to an unusual nonmonotonic dependence of the thermal conductivity on the length L of a ribbon. The effect is pronounced for the ribbons with the smooth edges (specularity parameter p > 0.5). Our results also suggest that, contrary to what was previously thought, the bulk-like three-dimensional phonons in graphite make a rather substantial contribution to its in-plane thermal conductivity. The Umklapp-limited thermal conductivity of graphite slabs scales, for L below ∼30 μm, as log(L), while for larger L, the thermal conductivity approaches a finite value following the dependence K 0 - A × L -1/2, where K 0 and A are parameters independent of the length. Our theoretical results clarify the scaling of the phonon thermal conductivity with the lateral sizes in graphene and graphite. The revealed anomalous dependence K(L) for the micrometer-size graphene ribbons can account for some of the discrepancy in reported experimental data for graphene. © 2012 American Chemical Society.


Balandin A.A.,University of California at Riverside | Nika D.L.,University of California at Riverside | Nika D.L.,Moldova State University
Materials Today | Year: 2012

Phonons - quanta of crystal lattice vibrations - reveal themselves in all electrical, thermal, and optical phenomena in materials. Nanostructures open exciting opportunities for tuning the phonon energy spectrum and related material properties for specific applications. The possibilities for controlled modification of the phonon interactions and transport - referred to as phonon engineering or phononics - increased even further with the advent of graphene and two-dimensional van der Waals materials. We describe methods for tuning the phonon spectrum and engineering the thermal properties of the low-dimensional materials via ribbon edges, grain boundaries, isotope composition, defect concentration, and atomic-plane orientation. © 2012 Elsevier Ltd.


Grant
Agency: European Commission | Branch: FP7 | Program: MC-IRSES | Phase: FP7-PEOPLE-2012-IRSES | Award Amount: 500.00K | Year: 2012

The main objective of this project is to create fundamental understanding in dynamical systems theory and to apply this theory in formulating and analyzing real world models met especially in Neuroscience, Plasma Physics and Medicine. The specific objectives, tasks and methodology of this proposal are contained in the 5 WPs of the project. In WP1 we want to develop new methods for the center and isochronicity problems for analytic and non-analytic systems, study bifurcations of limit cycles and critical periods, including time-reversible systems with perturbations, and investigate reaction-diffusion and fractional differential equations. In WP2 we deal with the problem of integrability for some differential systems with invariant algebraic curves, classification of cubic systems with a given number of invariant lines, study global attractors of almost periodic dynamical systems and their topological structure, respectively, Levitan/Bohr almost periodic motions of differential/difference equations. The main objective of WP3 is to study dynamics of some classes of continuous and discontinuous vector fields, preserving, respectively, breaking some symmetries, study of their singularities and closed orbits for classes of piecewise linear vector fields. WP4 deals with Hamiltonian systems in Plasma Physics, twist and non-twist area preserving maps, further studies of a recent model proposed to study some phenomena occurring in the process of plasmas fusion in Tokamaks, numerical methods, and the study of symmetries of certain kinds of k-cosymplectic Hamiltonians. The last WP tackles mathematical models in Neuroscience and Medicine. Firstly, we study several ODE-based and map-based neuronal models, survey in vivo results with respect to Autism Spectrum Disorder (ASD) and propose a model for ASD. Secondly, we study several approaches to mathematical models for diabetes. Finally, bone remodeling by means of convection-diffusion-reaction equations is our last task.


« UMTRI: average US new vehicle fuel economy drops in October | Main | Navigant forecasts global sales of electric drive buses to reach 181,000 in 2026 » An international team of scientists led by a researcher at the University of California, Riverside has modified the energy spectrum of acoustic phonons—elemental excitations, also referred to as quasi-particles, that spread heat through crystalline materials like a wave—by confining them to nanometer-scale semiconductor structures. The results, published in an open-access paper in the journal Nature Communications, have important implications in the thermal management of electronic devices. The project was led by Alexander Balandin, Distinguished Professor of Electrical and Computing Engineering and UC Presidential Chair Professor in UCR’s Bourns College of Engineering. The team used semiconductor nanowires from Gallium Arsenide (GaAs), synthesized by researchers in Finland, and an imaging technique called Brillouin-Mandelstam light scattering spectroscopy (BMS) to study the movement of phonons through the crystalline nanostructures. By changing the size and the shape of the GaAs nanostructures, the researchers were able to alter the energy spectrum, or dispersion, of acoustic phonons. The BMS instrument used for this study was built at UCR’s Phonon Optimized Engineered Materials (POEM) Center, which is directed by Balandin. Controlling phonon dispersion is crucial for improving heat removal from nanoscale electronic devices, which has become the major roadblock in allowing the engineers to continue to reduce their size. It can also be used to improve the efficiency of thermoelectric energy generation, Balandin said. In that case, decreasing thermal conductivity by phonons is beneficial for thermoelectric devices that generate energy by applying a temperature gradient to semiconductors. For years, the only envisioned method of changing the thermal conductivity of nanostructures was via acoustic phonon scattering with nanostructure boundaries and interfaces. We demonstrated experimentally that by spatially confining acoustic phonons in nanowires one can change their velocity, and the way they interact with electrons, magnons, and how they carry heat. Our work creates new opportunities for tuning thermal and electronic properties of semiconductor materials. In addition to Balandin, contributors to this paper included Fariborz Kargar, a graduate student and Ph.D. candidate in electrical and computer engineering at UCR and the lead author on the paper; Bishwajit Debnath, a graduate student in electrical and computer engineering at UCR; Kakko Joona Pekko, Antti Saynatjoki and Harri Lipsanen from Aalto University in Helsinki, Finland; Denis L. Nika, from Moldova State University in Chisinau, Moldova; and Roger K. Lake, professor of electrical and computer engineering at UCR. The work at UC Riverside was supported as part of the Spins and Heat in Nanoscale Electronic Systems (SHINES), an Energy Frontier Research Center funded by the U.S. Department of Energy, Office of Science, Basic Energy Sciences (BES) under Award # SC0012670.


News Article | November 11, 2016
Site: www.cemag.us

Controlling the flow of heat through semiconductor materials is an important challenge in developing smaller and faster computer chips, high-performance solar panels, and better lasers and biomedical devices. For the first time, an international team of scientists led by a researcher at the University of California, Riverside has modified the energy spectrum of acoustic phonons— elemental excitations, also referred to as quasi-particles, that spread heat through crystalline materials like a wave—by confining them to nanometer-scale semiconductor structures. The results have important implications in the thermal management of electronic devices. Led by Alexander Balandin, Distinguished Professor of Electrical and Computing Engineering and UC Presidential Chair Professor in UCR’s Bourns College of Engineering, the research is described in a paper published Thursday, Nov. 10, in the journal Nature Communications. The paper is titled “Direct observation of confined acoustic phonon polarization branches in free-standing nanowires.” The team used semiconductor nanowires from Gallium Arsenide (GaAs), synthesized by researchers in Finland, and an imaging technique called Brillouin-Mandelstam light scattering spectroscopy (BMS) to study the movement of phonons through the crystalline nanostructures. By changing the size and the shape of the GaAs nanostructures, the researchers were able to alter the energy spectrum, or dispersion, of acoustic phonons. The BMS instrument used for this study was built at UCR’s Phonon Optimized Engineered Materials (POEM) Center, which is directed by Balandin. Controlling phonon dispersion is crucial for improving heat removal from nanoscale electronic devices, which has become the major roadblock in allowing engineers to continue to reduce their size. It can also be used to improve the efficiency of thermoelectric energy generation, Balandin said. In that case, decreasing thermal conductivity by phonons is beneficial for thermoelectric devices that generate energy by applying a temperature gradient to semiconductors. “For years, the only envisioned method of changing the thermal conductivity of nanostructures was via acoustic phonon scattering with nanostructure boundaries and interfaces. We demonstrated experimentally that by spatially confining acoustic phonons in nanowires one can change their velocity, and the way they interact with electrons, magnons, and how they carry heat. Our work creates new opportunities for tuning thermal and electronic properties of semiconductor materials,” Balandin said. In addition to Balandin, contributors to this paper included Fariborz Kargar, a graduate student and Ph.D. candidate in electrical and computer engineering at UCR and the lead author on the paper; Bishwajit Debnath, a graduate student in electrical and computer engineering at UCR; Kakko Joona Pekko, Antti Saynatjoki and Harri Lipsanen from Aalto University in Helsinki, Finland; Denis L. Nika, from Moldova State University in Chisinau, Moldova; and Roger K. Lake, professor of electrical and computer engineering at UCR. The work at UC Riverside was supported as part of the Spins and Heat in Nanoscale Electronic Systems (SHINES), an Energy Frontier Research Center funded by the U.S. Department of Energy, Office of Science, Basic Energy Sciences (BES) under Award # SC0012670.


Home > Press > UCR researchers discover new method to dissipate heat in electronic devices: By modulating the flow of phonons through semiconductor nanowires, engineers can create smaller and faster devices Abstract: Controlling the flow of heat through semiconductor materials is an important challenge in developing smaller and faster computer chips, high-performance solar panels, and better lasers and biomedical devices. For the first time, an international team of scientists led by a researcher at the University of California, Riverside has modified the energy spectrum of acoustic phonons-- elemental excitations, also referred to as quasi-particles, that spread heat through crystalline materials like a wave--by confining them to nanometer-scale semiconductor structures. The results have important implications in the thermal management of electronic devices. Led by Alexander Balandin, Distinguished Professor of Electrical and Computing Engineering and UC Presidential Chair Professor in UCR's Bourns College of Engineering, the research is described in a paper published Thursday, Nov. 10, in the journal Nature Communications. The paper is titled "Direct observation of confined acoustic phonon polarization branches in free-standing nanowires." The team used semiconductor nanowires from Gallium Arsenide (GaAs), synthesized by researchers in Finland, and an imaging technique called Brillouin-Mandelstam light scattering spectroscopy (BMS) to study the movement of phonons through the crystalline nanostructures. By changing the size and the shape of the GaAs nanostructures, the researchers were able to alter the energy spectrum, or dispersion, of acoustic phonons. The BMS instrument used for this study was built at UCR's Phonon Optimized Engineered Materials (POEM) Center, which is directed by Balandin. Controlling phonon dispersion is crucial for improving heat removal from nanoscale electronic devices, which has become the major roadblock in allowing engineers to continue to reduce their size. It can also be used to improve the efficiency of thermoelectric energy generation, Balandin said. In that case, decreasing thermal conductivity by phonons is beneficial for thermoelectric devices that generate energy by applying a temperature gradient to semiconductors. "For years, the only envisioned method of changing the thermal conductivity of nanostructures was via acoustic phonon scattering with nanostructure boundaries and interfaces. We demonstrated experimentally that by spatially confining acoustic phonons in nanowires one can change their velocity, and the way they interact with electrons, magnons, and how they carry heat. Our work creates new opportunities for tuning thermal and electronic properties of semiconductor materials," Balandin said. ### In addition to Balandin, contributors to this paper included Fariborz Kargar, a graduate student and Ph.D. candidate in electrical and computer engineering at UCR and the lead author on the paper; Bishwajit Debnath, a graduate student in electrical and computer engineering at UCR; Kakko Joona Pekko, Antti Saynatjoki and Harri Lipsanen from Aalto University in Helsinki, Finland; Denis L. Nika, from Moldova State University in Chisinau, Moldova; and Roger K. Lake, professor of electrical and computer engineering at UCR. The work at UC Riverside was supported as part of the Spins and Heat in Nanoscale Electronic Systems (SHINES), an Energy Frontier Research Center funded by the U.S. Department of Energy, Office of Science, Basic Energy Sciences (BES) under Award # SC0012670. For more information, please click If you have a comment, please us. Issuers of news releases, not 7th Wave, Inc. or Nanotechnology Now, are solely responsible for the accuracy of the content.


News Article | November 10, 2016
Site: www.eurekalert.org

RIVERSIDE, Calif. -- Controlling the flow of heat through semiconductor materials is an important challenge in developing smaller and faster computer chips, high-performance solar panels, and better lasers and biomedical devices. For the first time, an international team of scientists led by a researcher at the University of California, Riverside has modified the energy spectrum of acoustic phonons-- elemental excitations, also referred to as quasi-particles, that spread heat through crystalline materials like a wave--by confining them to nanometer-scale semiconductor structures. The results have important implications in the thermal management of electronic devices. Led by Alexander Balandin, Distinguished Professor of Electrical and Computing Engineering and UC Presidential Chair Professor in UCR's Bourns College of Engineering, the research is described in a paper published Thursday, Nov. 10, in the journal Nature Communications. The paper is titled "Direct observation of confined acoustic phonon polarization branches in free-standing nanowires." The team used semiconductor nanowires from Gallium Arsenide (GaAs), synthesized by researchers in Finland, and an imaging technique called Brillouin-Mandelstam light scattering spectroscopy (BMS) to study the movement of phonons through the crystalline nanostructures. By changing the size and the shape of the GaAs nanostructures, the researchers were able to alter the energy spectrum, or dispersion, of acoustic phonons. The BMS instrument used for this study was built at UCR's Phonon Optimized Engineered Materials (POEM) Center, which is directed by Balandin. Controlling phonon dispersion is crucial for improving heat removal from nanoscale electronic devices, which has become the major roadblock in allowing engineers to continue to reduce their size. It can also be used to improve the efficiency of thermoelectric energy generation, Balandin said. In that case, decreasing thermal conductivity by phonons is beneficial for thermoelectric devices that generate energy by applying a temperature gradient to semiconductors. "For years, the only envisioned method of changing the thermal conductivity of nanostructures was via acoustic phonon scattering with nanostructure boundaries and interfaces. We demonstrated experimentally that by spatially confining acoustic phonons in nanowires one can change their velocity, and the way they interact with electrons, magnons, and how they carry heat. Our work creates new opportunities for tuning thermal and electronic properties of semiconductor materials," Balandin said. In addition to Balandin, contributors to this paper included Fariborz Kargar, a graduate student and Ph.D. candidate in electrical and computer engineering at UCR and the lead author on the paper; Bishwajit Debnath, a graduate student in electrical and computer engineering at UCR; Kakko Joona Pekko, Antti Saynatjoki and Harri Lipsanen from Aalto University in Helsinki, Finland; Denis L. Nika, from Moldova State University in Chisinau, Moldova; and Roger K. Lake, professor of electrical and computer engineering at UCR. The work at UC Riverside was supported as part of the Spins and Heat in Nanoscale Electronic Systems (SHINES), an Energy Frontier Research Center funded by the U.S. Department of Energy, Office of Science, Basic Energy Sciences (BES) under Award # SC0012670.


Grant
Agency: European Commission | Branch: FP7 | Program: MC-IRSES | Phase: FP7-PEOPLE-2012-IRSES | Award Amount: 589.00K | Year: 2013

The research will cover areas of the EU-Moldova and EU-Georgia cooperation, linked to both, the European Neighbourhood Policy Action Plan and the EU conditionality. It looks at Moldovas and Georgias economic, legal and political situation and development. The focus of the project and project-related research is structuring the CEE states reform experience and analysing the possibilities and limits of transferring the best practices and experience to Moldovas and Georgias (possible) EU pre-accession process. It analyses the situation in Moldova and Georgia and suggests benchmarking opportunities best suitable for Moldova and Georgia. The results of the analysis and researchers/lecturers exchange are wrapped up via regular thematic workshops and publications. The output of the research results is also used in improving and developing the European Union-related curricula and courses in all participating universites: in Tartu, Vilnius, Moldova and Georgia. Work Packages are as follows: 1. Mapping CEE states reform experience: environment of positive conditionality mapping of success and failure of reforms in key policy areas related to EU accession criteria (Progress Report Chapters); 2. European Neighbourhood Policy and Europeanization (political, economic and legal aspects) analysing which CEE states pre-accession knowledge is transferable and needed; 3. Moldova and Georgia the transition countries on the EU border and states between EU and Russia analysing the specific circumstances and policy trends; 4. Teaching EU, EU-Russia relations and European Neighbourhood Policy in the context of interdisciplinary European Studies curricula.


Chirita A.,Moldova State University
Journal of Modern Optics | Year: 2010

The processes of micro-object hologram real-time recording on a photo-thermo-plastic carrier based on a chalcogenide glassy semiconductor As-Se-S-Sn system were studied. The possibility to measure micro-object dimensions using an interference fringe pattern was shown. Double-exposure hologram recording by use of photo-induced structural transformation processes in a photo-semiconductor and photo-thermoplastic recording process was investigated. © 2010 Taylor & Francis.


Seremet V.,Moldova State University
Acta Mechanica | Year: 2014

This paper is devoted to a new approach for the derivation of main thermoelastic Green's functions (MTGFs), based on their new integral representations via Green's functions for Poisson's equation. These integral representations have permitted us to derive in elementary functions new MTGFs and new Poisson-type integral formulas for a thermoelastic octant under mixed mechanical and thermal boundary conditions, which are formulated in a special theorem. Examples of validation of the obtained MTGFs are presented. The effectiveness of the obtained MTGFs and of the Poisson-type integral formula is shown on a solution in elementary functions of a particular BVP of thermoelasticity for octant. The graphical and numerical computer evaluation of the obtained MTGFs and of the thermoelastic displacements of the particular BVP for an octant is also presented. By using the proposed approach, it is possible to derive in elementary functions many new MTGFs and new Poisson-type integral formulas for many canonical Cartesian domains. © 2013 Springer-Verlag Wien.

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