3^rd International Conference on Theoretical and Condensed Matter Physics October 19-21, 2017 New York, USA

Biography:

Utpal Chatterjee has completed his PhD from University of Illinois at Chicago in 2007. Afterwards, he has conducted his Postdoctoral studies at Matreials Science Division of Argonne National Laboratory with Director’s fellowship. He has joined University of Virginia in 2012. His research is focused on experimental study of strongly correlated electronic systems. His principal expertise in angle resolved photoemission spectroscopy. His research over past 10 years has produced many high impact publications, which include Nat. Commun, 2015; 6: 6313 DOI: 10.1038/ncomms 7313, Nat. Phys. 10, 357; PNAS 110, 17774; PNAS 108, 9346; Nat. Phys. 6, 99; PRL 96, 107006.

Abstract:

Recently, the studies of incommensurate charge density wave (CDW) phases in various 2H-polytypes of transition metal dichalcogenides (TMDs), e.g., 2H-NbSe2 and 2H-TaSe2, have attracted a lot of attention due to intriguing experimental observations, some of which are reminiscent of the enigmatic pseudogap phase in cuprate high temperature superconductors (HTSCs). We present a comprehensive Angle Resolved Photoemission spectroscopy. ARPES) study on 2H-TaS2, a canonical incommensurate CDW material. Comparing our ARPES data together with arguments based on a tight-binding analysis on 2H-TaS2, with those on related materials like 2H-NbSe2 and 2H-TaSe2, we identify the generic and system-specific characteristics of these systems. We find the following generic features of incommensurate CDW TMDs: (i) opening of CDW energy gap (Δcdw) along part of the underlying Fermi Surface (FS) sheets; (ii) finite Δcdw at temperatures above the CDW transition temperatures and particle-hole asymmetry in Δcdw and a lack of one-to-one correspondence between CDW wave vectors and the FS nesting vectors. We have also observed some system-specific features. For example, in contrast to 2H-NbSe2, where Δcdw is non-zero only at a few “hot spots” on a specific FS sheet, Δcdw in 2H-TaS2 is non-zero along the entirety of multiple FS sheets. Using a tight-binding model, we describe this in terms of the difference in the orbital orientations of their electronic states close to the Fermi level. In short, our strong-coupling model can describe both the generic and the material-specific features of these compounds. Therefore, we argue that the strong electron-phonon coupling, including its orbital and momentum-dependence, is key to the incommensurate CDW instability in TMDs.

Biography:

Yshai Avishai (PhD at Weizmann institute), is a professor of theoretical condensed matter Physics at Ben Gurion University, Beer Sheva Israel. He is a fellow of the American Physical Society, and during 2008-2014 he served as a Divisional Associate Editor for Physical Review Letters. In 2014 he was an Outstanding Referee for APS journals. Professor Avishai served as head of the Physics Department at Ben Gurion University, as head of the Ilse-Katz Center for Nanotechnology, as member of the Judging Committees, for Israel prize in Physics and the Emet prize for exact Sciences. He is the author of 235 papers in high level journals including Physical Review Letters and Nature, and an author of three books in Physics. Professor Avishai occasionally serves as Faculty Member at NYU-Shanghai University, and he is an affiliated professor (2017) of the Yukawa Institute of Theoretical Physics at Kyoto Japan. He visited and worked in numerous institutes around the world, Including Argonne National Laboratories, Lyon, Saclay, Orsay, Heidelberg, Tokyo, Kyoto, Hokkaido and others. Professor Avishai holds also a second degree in Economics and speaks numerous languages including French and Japanese. He is also an amateur Piano player.

Abstract:

The feasibility of manipulating a Fermi gas of cold atoms with spin s>1/2 in a specially designed optical potential enables studying a new kind of topological insulators, described by a two band model where cold fermionic atoms with spin s=3/2 occupy a two dimensional optical lattice where spin orbit coupling is relevant. The pertinent time-reversal invariant Hamiltonian is an 8x8 matrix in [spin]x[particle-hole] spaces, whose spectrum and topological properties are remarkably distinct from those encountered for spin 1/2 fermions. Specifically, on each edge of the 2D sample there are two pairs of oppositely propagating helical states. The two states in each pair move along the same direction, but they are protected against scattering with each other: they have different quantum numbers and different dispersion: (E1 proportional to k and E2 proportional to k^3). Strikingly, the corresponding bulk topological numbers are Z1=2 and Z2=0. Thus, the ubiquitous bulk-edge correspondence is broken here because the group velocity (and hence the conductivity) associated with the second edge state vanishes at k=0.

Biography:

Avik Ghosh is Professor of Electrical and Computer Engineering and Professor of Physics at the University of Virginia. He has over 100 refereed papers and book chapters and 2 upcoming books in the areas of computational nano-electronics and low power devices including 2D materials, molecular electronics, low-power devices, nanomagnetism, photodetectors and nanoscale heat flow. Ghosh did his PhD in physics from the Ohio State University and Postdoctoral Fellowship in Electrical Engineering at Purdue University. He is a Fellow of the Institute of Physics (IOP), senior member of the IEEE, and has received the IBM Faculty Award, the NSF CAREER Award, a best paper award from the Army Research Office, the Charles Brown New Faculty Teaching Award and the UVA's all University Teaching Award. His group's research on observing negative index behavior in graphene was voted by Physics World as one of the top-10 Breakthroughs of 2016.

Abstract:

With the current slow-down of Moore's law and the abolition of the ITRS roadmap, there is a pressing need to explore various materials, architectural and physical solutions for low-power electronics, ranging from spintronics to 2D materials to subthermal switching that beats the fundamental Boltzmann limit. Graphene and other 2D materials have been widely studied because of their photon-like band structure and high mobility. However, their gaplessness compromises their ability to switch under gate bias. I will discuss how using a sequence of gated PN junctions, we can make electron flow in graphene resemble optics-with unconventional equivalents of Snell's law for trajectories, Fresnel equation for transmission, Malus' law for polarization and cut-off modes of a waveguide. These equivalents (negative index, Klein tunneling and Veselago focusing) can be used to filter electrons and engineer a gate-tunable transport gap that allows us to turn off the electron flow abruptly without hurting the mobility of the on current. This novel switching has implications for both digital devices and high speed analog RF applications. Extended to 3D topological insulators, the unconventional switching allows us to filter the spins, amplifying their torque at an injecting ferromagnetic by giving us a gate-tunable giant spin hall angle.

Biography:

Patrick M Vora has received a PhD in Physics from the University of Pennsylvania. Subsequently, he was a Postdoctoral Fellow at the University of Pennsylvania and later at the US Naval Research Laboratory as a part of the National Research Council’s Research Associateship Program. He was named an Assistant Professor at George Mason University in 2014 where he has established a research group that focuses on two-dimensional materials. He has published 22 papers in reputed journals.

Abstract:

The structural polymorphism intrinsic to transition metal dichalcogenides provides exciting opportunities for engineering novel devices. Of special interest are memory technologies that rely upon controlled changes in crystal phase, collectively known as phase change memories (PCMs). MoTe2 is ideal for PCMs as the ground state energy difference between the hexagonal (2H, semiconducting) and monoclinic (1T’, metallic) phases is minimal. This energy difference can be further reduced by substituting W for Mo on the metal sublattice, thus improving PCM performance. Therefore, understanding the properties of Mo1-xWxTe2 alloys across the entire compositional range is vital for the technological application of these versatile materials. We combine Raman spectroscopy with aberration-corrected scanning transmission electron microscopy and x-ray diffraction to explore the MoTe2-WTe2 alloy system. The results of these studies enable the construction of the complete alloy phase diagram, while polarization-resolved Raman measurements provide phonon mode and symmetry assignments for all compositions. Temperature-dependent Raman measurements indicate a transition from 1T’-MoTe2 to a distorted orthorhombic phase (Td) below 250 K and facilitate identification of the harmonic contributions to the optical phonon modes in bulk MoTe2 and Mo1-xWxTe2 alloys. We also identify a Ramanforbidden MoTe2 mode that is activated by compositional disorder and find that the main WTe2 Raman peak is asymmetric for x<1. This asymmetry is well-fit by a phonon confinement model, which allows the determination of the phonon correlation length. Our work is foundational for future studies of MoxW1-xTe2 alloys and provides new insights into the impact of disorders in transition metal dichalcogenides.

Biography:

V P Maslov is a professor of National Research University, Higher School of Economics (School of Applied Mathematics). In 1984, he was elected to Full Membership of the Mathematical section of Russian Academy of Sciences directly, without passing through the Corresponding Member stage. He has published over 600 papers and over 20 monographs. He has introduced a series of important notions of which Maslov-type index theory, Maslov classes, Maslov form, Maslov correction, Maslov WKB method, Maslov cycle, Maslov dequantization are best known.

Abstract:

Quantum mechanics has established a new physical picture of the world, a significant contribution being due to the famous treatise “Theoretical Physics” by Landau and Lifshits. In the “Statistical Physics” volume, they obtained the main equations ofthermodynamics without resorting to the so-called three main principles of thermodynamics, which appear in all thermodynamics textbooks. Bohr’s liquid-drop model of nucleus does not involve attraction interaction of particles and is based on a potential well common for all nucleus elements. Our concept of thermodynamics is based on quantum mechanics and the Earth’s gravitational attraction as an element of a common potential well. We say that a condensate is soft if the gravitational forces push the heavier clusters of the solution to the bottom of the vessel, where they form a thin heavy liquid layer without becoming a hard precipitate. Thus, the critical isochore separates fluids into soft and heavy ones. This approach allows describing the behavior of isotherms in the domain of heavy fluids and determining the weight of heavy clusters for each gas. Our model of thermodynamics shows good agreement with experimental data and explains effects such as negative pressure and liquid–solid phase transition based solely on collisions between molecules and the Earth’s gravitational attraction without using attraction between molecules. N Bohr (1938) noticed the deep relationship between nuclear fission and the partition problem in number theory. The author involves methods of number theory as the third constituent of a new model of thermodynamics. This model does not apply to satellites, where weightlessness occurs.

Biography:

Ceballos Garzón Ricardo has a degree in Physics from the National  Pedagogical University, Physics Specialist from the National University of Colombia, Magister in Geophysics of the Central University of Venezuela, PhD student in Engineering Sciences from the Central University of Venezuela.

Carrillo Guerrero Sergio is a Physicist from the National University of Colombia, M.Sc in Physics from the National University of Colombia, Ph.D in Materials Science from the University of Lille 1.

Abstract:

We carry out the study of a theory based on the properties of transport, with the purpose of obtaining a detailed description of the process of optic absorption in the semiconductors. We have derived expressions that show the relationship between the spectra of absorption and the conductivity of the crystals starting from those properties of transport (conductivity) and of the optic transitions. Such a correlation settled down keeping in mind that the model Tight Binding can be used to show the correlation of the moment matrix elements with the optical matrix elements. The relationship between the conductivity and the infuence of the external field was established, including the importance of the optical constants of the material. When delving into the relationship between the absorption spectrum and the electrical conductivity tensor in the semiconductors it was possible to obtain the description of the optical absorption spectrum in terms of the electric conductivity tensor. Intraband absorption in PbSe QD's is present in a broad wavelength range. Broadband response in near to mid-infrared range can be very relevant for ultra high speed all-optical signal processing (telecom applications). Dominant e_ect from the PbSe core in PbSe/CdSe QD's: electronic structure (bandgap, SP splitting), absorption. CdSe QD's show new high intraband peaks corresponding to hole transitions.

Biography:

Anant Raj received his Undergraduate Degree in Mechanical Engineering from the Indian Institute of Technology, Kanpur in 2010. He received a Master’s degree in Nuclear Engineering from the North Carolina State University, Raleigh in 2013 and continued to pursue a PhD degree under the guidance of Prof Jacob Eapen. During his graduate studies, he was introduced to the fascinating field of materials science and the intricacies of probing materials behavior using statistical mechanics and atomistic simulations. He received his PhD on phonon dynamics and beyond-phonon descriptors for energy transport in materials. He is currently working as a Post-doctoral Research Scholar at the North Carolina State University.

Abstract:

Energy transport in low dimensional systems has been of interest for over 60 years, since the seminal paper by Fermi, Pasta, and Ulam on the vibrational modes of a one-dimensional non-linear string, popularly known as the FPU problem. Several studies have demonstrated that unlike bulk three-dimensional systems, the energy transport in low dimensional systems does not follow Fourier’s law of heat conduction. The thermal conductivity for these systems is ill-defined and is reported to diverge, scaling with the size of the system. Such divergence is also observed in realistic polymer chains as well as in two dimensional materials such as graphene. More recently, this anomalous behavior has been linked to the presence of cross-correlation between different phonon modes arising from collective phonon excitations. To elucidate the relationship between the phonon modes and energy transport more deeply, we analyze the local energy fluctuations of a linear mono-atomic chain and relate them to the phonon modes. We demonstrate theoretically that normal modes of the displacements interfere to produce energy wave packets. We further derive the condition that pairs of phonon modes interfere to produce waves of energy if and only if three-phonon scattering law is satisfied by the trio, even in the absence of phonon-phonon scattering. In general, for nth order in the interaction potential, n displacement normal modes combine to form energy waves if and only if (n+1)th order phonon scattering law is satisfied between them. Further, we show that the frequency and decay of the energy normal modes are directly associated with the collective excitation of phonon modes. Our theoretical findings link the established theory of phonon excitation modes to the normal modes of energy in crystal lattices from statistical-mechanical first principles.

Biography:

Leonardo dos Santos Lima has completed his PhD from Federal University of Minas Gerais, Brazil and Postdoctoral studies from Technische Universität Kaiserslautern, Germany. He has published more than 35 papers in reputed journals.

Abstract:

We use the SU(3) Schwinger's boson theory to study the spin transport properties of two-dimensional anisotropic frustrated Heisenberg model at T=0. We have investigated the behavior of the spin conductivity in diferent frustrated spin systems that presents exchange interactions J1, J2 and J3. We have studied the spin transport in the Bose-Einstein condensation regime where the bosons tz are condensed. Our results show an influence of the quantum phase transition point on the spin conductivity behavior. We also have made a diagrammatic expansion for the green-function and do not have obtained any significative change on the results.

Biography:

Eliade Stefanescu graduated the Faculty of Electronics, Section of Physicist Engineers, in 1970, and obtained a PhD in Theoretical Physics in 1990. As a Scientist from 1976, a Senior Scientist III from 1978, he worked in physics and technology of semiconductor devices, and from 1978, he worked in physics of optoelectronic devices. From 1987, and from 1990 as a Senior Scientist II, he worked in the field of open quantum physics. In the years 1995-2000, he held a course called Dissipative Systems for the master degree. In 1991 he discovered that the penetrability of a potential barrier can be increased by coupling to a dissipative system, and described the decay spectrum of some cold fission modes. As a Senior Scientist I, from 1997 he developed a microscopic theory of open quantum systems, and discovered a physical principle for the heat conversion into usable energy. In 2014, he produced a unitary relativistic quantum theory. He received the Prize of the Romanian Academy for Physics in 1983, Diploma as Ordinary Member of the Academy of Romanian Scientists, Diploma and Golden Plate as Founder of the Academy of Romanian Scientists, and the Prize “Serban Titeica” (2014) for the book “Open Quantum Physics”.

Abstract:

Recently, we conceived a semiconductor structure converting environmental heat into electromagnetic energy and, further, into electric energy: while a current I is injected in the device, a super radiant field is generated by quantum transitions of electrons from the n-zones to the p-zones. We notice that this current enhances the lower states of the ohmic contacts between the n-p super radiant junctions, while the upper states of these contacts are depleted. This makes these contacts become colder, the current I traversing these contacts by thermal excitations of electrons, on the account of the heat absorption from the surrounding zones. This is a complex process based on the quantum dynamics of three coupled physical systems: (1) the active electrons in the quantum wells of the super radiant junctions, (2) the electromagnetic field in the device cavity, and (3) the optical vibrations of the crystal lattice, leading to an approximately 3 times variation of the field propagation velocity, according to the crystal refractive index. The dynamics of these systems includes an important dissipative component due to the couplings to the other electrons and to the mechanical vibrations of the crystal. We describe the dissipative quantum dynamics of the three systems by quantum master equations with explicit microscopic coefficients depending on the physical characteristics of the device. We understand the electron and electromagnetic field dynamics in the framework of a unitary relativistic quantum theory. In this theory, a quantum particle is described by wave packets in the two spaces of the coordinates and momenta, of a form providing the Hamilton equations as group velocities of the two wave packets, which include the Lagrangian instead of the Hamiltonian in the conventional wave functions. Unlike the classical relativistic principle of the light velocity consistency, we consider a relativistic quantum principle of invariance of the time dependent phase of a quantum particle.

Biography:

Manuel S Morales is an independent researcher in the field of fundamental mechanics, i.e., origin physics. He has a BFA in illustration and AS in photography. His notable career as an artist inadvertently led to conducting a twelve year experiment at TemptDestiny.com which revealed that the current methods and theories of science are incomplete. He has applied his findings to particle physics, theoretical physics, experimental physics, and has served as a referee for a number of physics journals.

Abstract:

In a twelve year experiment it has been empirically confirmed, without ambiguity, that there are two mutually exclusive and jointly exhaustive (hidden) variables that give rise to existence. What has been revealed is that the two acts of selection are not effects of cognition. They are origin variables of physical existence. This bold claim can be confirmed by all via a simple thought experiment or empirically validated in real life. The findings show that the two complimentary dichotomies of selection can only come to exist not preexist or be existent. As such, they serve to give rise to effects of existence, i.e., matter and the four fundamental forces of nature. Graph analysis of the findings illustrate the construct of how an act (x) directly pairs with its potential (y) in order to become a direct selection dichotomy (z) and how an act (-x) indirectly pairs with its potential (y) in order to become an indirect selection dichotomy (-z). Together, both dichotomies create an X pattern similar to the X-ray diffraction photograph of the famed DNA image taken by Raymond Gosling in May 1952. The difference between the two observations is that one creates an X pattern while the photograph records the effect of an X pattern which in turn prompts further investigation. DNA is known to carry the genetic code of cells and some viruses. The two acts of selection serve to generate everything that exists. Exploration of how the fundamental laws of selection generate genetic codes hopes to open new fields of research that will bridge physics with genetics.

Biography:

Holger Bech Nielsen is Professor emeritus at the Niels Bohr Institute and reputed for being one of the inventors of string theory, vortex lines line paper with P Olesen, Nielsen-Ninomiya (Foerster) No go theorem for chiral Fermions on the lattice, Forggat-Nielsen mechanism for masses of fermions in the Standard Model, and has been very keen on developing his dream of Random Dynamics, that the laws of nature shall come out automatically almost whatever the fundamental theory is taken to be. He gives many popular talks on high energy physics. Recently, he works on the suggested new law of nature Multiple Point Principle, from which coupling constants get restricted (predicted the Higgs mass). The Humboldt prize visiting DESY and several ca 8month visits to CERN.

Abstract:

It is an old idea of ours (H. B. “Nielsen Dual Models'' section 6 “Catastrophe Theory Program'' Scottish University Summer school 1976?) that a most general material with only translation symmetry, but otherwise no symmetries should generically (in general) have some small regions in quasi momentum space, where you ''see" an approximate Weyl equation behavior. The Weyl equation is the relativistic equation for a (left handed) neutrino. This remark means that one could imagine, that there were behind the Standard Model of High energy physics, a very general crystal model with very little symmetry. Even for the Yang Mill or electrodynamics types fields a similar philosophy is possible. There are though some problems with this solid-state type of model beyond the Standard model, for which we thought have some remedy by means of homolumo gap effects. Now a days, the kind of material on which we speculated is being found and very high conductivity achieved for them.

Biography:

Loris Ferrari is graduated in Physics at the University of Bologna, with highest praise. He was awarded with Guglielmo Marconi prize in 1974. He became Assistant of Analytical Mechanics at University of Ferrara (Italy). He became Associate Professor of Condensed Matter Physics in 1981. Since 1985 he held a number of courses in the field of condensed matter at the Department of Physics of the University of Bologna. His research work was initially concerned with glasses and glass transition. In this period he cooperated with Sir N F Mott and W A Phillips of the University of Cambridge. Then he worked in the field of renormalization group theory and non autonomous quantum systems. At present, he works on ultracold bosonic systems and superfluidity. He has published about 80 papers in reputated scientific reviews.

Abstract:

In a gas of N interacting bosons, Bogoliubov’s first step is dropping all the interaction terms between free bosons with moment ,which leads to the truncated Hamiltonian Hc. Bogoliubov’s second step (Bogoliubov Canonic Approximation) is approssimating Hc with a bi-linear canonic form HBCA in the creation/annihilation operators, which can be diagonalized by the well known Bogoliubov transformations. All this leads to the current notion of quasiphonons, i.e. collective bosonic excitation, with wave-like character (at low k), each carrying a finite moment Here we show what happens when Hc is diagonalized exactly. The resulting eigenstates depend on two discrete indices where numerates the quasiphonons carrying a moment , responsible for transport or dissipation processes. S, in turn, numerates a ladder of vacua , with increasing equispaced energies, formed by boson pairs with opposite moment. Passing from one vacuum to another , results from creation/annihilation of new momentless collective excitations, reminiscent of bosonic cooper pairs, that we call pseudo-bosons. Exact quasiphonons originate from one of the vacua by creating an asymmetry in the number of opposite moment bosons. The well known Bogoliubov quasiphonons (QPs) are shown to coincide with the exact eigenstates , i.e. with the QPs created from the lowest-level vacuum (S=0). All this is discussed, in view of existing or future experimental observations of what we call the hidden side of Bogoliubov collective excitations (CEs), i.e. the
pseudobosons.

Biography:

Eugene Machusky is currently Head of the Dept. of Technical Information Protection Systems, Scientific Director of Special Design Bureau "Storm" in National Technical University of Ukraine "Kyiv Polytechnic Institute" (KPI), Kyiv, Ukraine. He received his MEng (1974), PhD (1979), DSc (1989) from NTUU "KPI". He has been a Research Visitor at the University of North Wales (1983-1984, Bangor, UK), Visiting Professor at Harbin Technological University (2015-2018), China. He has also been an Author and Editor of Radio Engineering Encyclopaedia (Kyiv 1999; Moscow 2002, 2009, 2016), Articles in Great Ukrainian Encyclopedia (2016-2017). His scientific fields of interest includes microwave electronics, underwater acoustics, information security, mathematical linguistics.

Abstract:

For the first time, the Unified Quantum Metric system was analytically developed without any artifacts, such as m, s, kg and without measurements at all. The energy diagrams of Feynman were replaced by calculations of harmonic space-time differentials. The main constants of quantum physics are, in fact, dynamic gradients of normal, half-normal, log-normal and truncated normal distribution of inverse radius of pulsing spiral. The Quantum Physics is the logarithmically compressed two-dimensional image of threedimensional motion of wave fronts. One matrix equation [Gi]=2*PI*[Ri]*(1+[Ai]) where Ai, Ri, Gi are eccentricity, radius, density correspondingly, completely describe the 3D motion of wave fronts. Radii and eccentricities are bonded by the argument of information entropy Sqrt(2*PI*E) of the function of normal distribution Ri = 1+2/100*(E +Ai*(1+Sqrt(2*PI*E/100))). Lower limit of the nuclear rotational radius of pulsing spiral R = Integer{10^8*(C/10^7)^(1/64)/10^8 = 1.05456978 corresponds to upper limit of the harmonic rotational speed. C = (R+4*PI*C/10^18)^64*10^7 = 299792457.86759 (Maxwell unit) and K=E+AS+BS=2.7315999984590452 (upper limit of background temperature, Kelvin unit) link electrodynamics and thermodynamics. The number AS = 0.00729 = 1/100/(1.11111111...)^3=1/100/Sum{[137+(137-100)*N]/10^(3*N+2)} is the Schrodinger quantum binary inverse integral number.The number BS=Sum{602214183/10^(3*N+11)}=0.0060281699999…=0.00602817 (Avogadro quantum decimal integral number) connects binary and decimal calculation systems The thirteen digital sequences are sufficient for estimating all fundamental quantumconstants with practically unlimited accuracy.

The following equations functionally links binary, decimal and natural quantum calculation systems (bit-dit-nat): A1=1/137, A0=(PI*E/100)^2, A4=A0+4*(A1-A0), AH=1/(4^2*PI*E), AL=(1+59*Ln(10)), AF=1000/Inteer{1000*Sqrt(137^2+PI^2)},RC=R+4*PI*C/10^18,RE=R+1/E/10^8, RA=R+1/(E+AS)/10^8, RK=R+1/K/10^8, NB=602214183/(1+4*PI/10^8)/10^8=6.022141073235 (reference number of differential entropy, lower limit of harmonic Avogadro unit), [Ni]=(Sqrt(8*PI*E/(8*PI*E+137^2))/(1+2*[Ai]/1000)-1/2/10^7)/10 (Avogadro energy entropy matrix), [MMi]=12-[Ai]/10 (molar mass entropy matrix), [KBI]=Cos(12-[Ai]/10)-Sin(12-[Ai]/10) (Boltzmann phase entropy matrix), [Vi]=[Ri]^64*10^7 (translation speed entropy matrix), AX=5/Root{X*E^X/(E^X-1)=5}=0.0070261763632109 (lower limit of relative inverse eccentrisity, Wien referenceunit).

Biography:

Mohammed Ä°brahim has completed his PhD at University of Technology (IRAQ) in Material Science on 1996 and he got his MSc degree from University of Glasgow (UK) in Reactor Technology (1985). He has published more than 40 scientific papers in material technology in scientific journals and has been serving as Researcher and Teaching Staff in University Of Technology/Chemical Engineering Department. Currently, he is working as an academic staff in Chemical Engineering Department, Faculty of Engineering, Sulyeman Demirel University-Isparta-Turkey.

Abstract:

In recent years, using nanofluids to increase the heat transfer is gaining much more attention among engineers and researchers. Nanofluids are comprised of a concentration of nanoscale sized particles dispersed in a base fluid. The particles can be composed of any type of material, examples include pure metals, oxides, carbides and carbon nanotubes. The base fluid can be any material from pure water, ionic liquids, oils, to diluted organic compounds such as ethylene glycol and oleic acid. A chance to increase the heat transfer by employing nanofluids have opened the way for a spectrum of promising applications like miniature electronic devices, high power electric devices like transformers and enhanced heat transfer in many other energy conversion systems. Magnetic nanofluids also called as ferrofluids, consists of colloidal mixtures of super paramagnetic nanoparticles suspended in a nonmagnetic carrier fluid, constitute a special class of nanofluids exhibiting both magnetic and fluid properties. In these suspensions, also known as smart or functional fluids all features such as fluid flow, particles movement and heat transfer process can be controlled by applying external magnetic fields. In the present work, we proposed to synthesize water base nanofluids consisting of magnetic Graphene-Fe (Ge-Fe) nanocomposite and to study the fluid thermal conductivity in presence and in absence of magnetic field. Graphene was prepared by exfoliation method and graphene-Fe nanocomposite was prepared by co-precipitation of Fe2O3 (over graphene) from aqueous salt solution in alkaline medium. Synthesis of nanofluid has been done by well dispersed of Ge-Fe in a certain fluid. The results obtained showed that, the disperssion of these nanoparticles in fluid, as a magnetic nanoparticle increased the efficiency of nanofluid (when graphene is used alone) and a significant improvment in thermal conductivity has been obtained by addition of Fe to graphene sheets. When the magnetic field is applied, the magnetic dipole moments of the particles align and the particles came in contact with each other and form chains in the direction of the applied magnetic field. When parallel to the direction of heat flow, the magnetic field causes the effective thermal conductivity in the direction of the magnetic field to increase. Characterization techniques like X-ray diffraction (XRD), Scanning electron microscope (SEM),Transmission electron microscope (TEM),Raman shift spectroscopy were used to investigate the morphology and structure of synthesized nanoparticles, while thermal conductivity of nanofluid at different conditions is measured by thermal conductivity meters and temperature thermocouples readings.

Biography:

Numerical methods for differential equations are one of the notable glories of contemporary science. Coupled with much algorithmic ingenuity, numerical methods are widely applied across science and engineering fields. One of the most important numerical methods is the numerical integration which has been the focus of intense research since its development in 1915 by David Gibb. In this abstract, we present the study of numerical integrator based on Fer expansion in the integration of the time-dependent Schrodinger equation (TDSE) which is a central problem to nuclear magnetic resonance (NMR) in general and solid-state NMR in particular. Numerical simulations of NMR experiments are often required for the development of new techniques and for the extraction of structural and dynamic information from the spectra. The development and design of various pulse sequences and understanding of different NMR experiments are based on the form of effective Hamiltonian or effective propagator that satisfies the TDSE which is difficult to solve unless the Hamiltonian is time independent or commutes with itself at two different times. The evolution operator allows obtaining the density matrix of the spin system that has evolved from the equilibrium density matrix due to the application of RF irradiation. The signal intensity depends on the final density matrix of the spin system. For example, if the numerical model is implemented with the approximate solutions of Fer or Magnus, the results of the simulation will show incorrect or undesirable effects of finite pulses and ring-down mainly when dealing with quadrupolar nuclei (I>1/2). In this study we proposed an efficient numerical integrator based on Fer expansion for solving the TDSE to obtain an effective propagator that continually improves the detected NMR signal. We will also compare the performance of the numerical integrator based on Fer expansion with respect to other Lie-group solvers, namely Magnus and Cayley methods.

Abstract:

Eugene Stephane Mananga is a Faculty Member in the Physics Doctorate Program and in the PhD Program in Chemistry at the Graduate Center of the City University of New York. He is an Assistant Professor of Physics and Nuclear Medicine at BCC of CUNY, and an Adjunct Professor of Applied Physics at New York University. He completed his PhD in Physics from the Graduate Center of the City University of New York, and holds six additional graduate degrees and training from various institutions including Harvard University (HMS), Massachusetts General Hospital (MGH), and City College of New York. He did his Postdoctoral studies in the National High Magnetic Field Laboratory of USA, Harvard Medical School, and Massachusetts General Hospital. Prior to joining Harvard - MGH, he was a Research Engineer in the French Atomic Energy Commission and Alternative Energies. He has published more than 40 peer-review scientific articles including prestigious scientific journals and he has been serving as Editorial Board Member for more than 20 remarkable journals. He currently serves as Editor-in-Chief of the Journal of Imaging Science. His scientific contribution was honored during the 70th anniversary (1946-2016) of the Russian Academic of Sciences.

Biography:

Hafiz Muhammad Asif Javed has completed his PhD from Electronic Materials Research Laboratory, School of Electronic and Information Engineering, Xi’an Jiaotong University, Xi’an China. He is an Assistant Professor of Physics at University of Agriculture Faisalabad Pakistan. He has published more than 12 papers in well reputed journals. His current research interests include advanced energy nanomaterials, organic–inorganic hybrid nanomaterials for solar cells, TiO2 nanotubes/nanowires arrays, ZnO nanowires arrays and SnO2 nanotube arrays sensitized with semiconductor quantum dots or organic dyes for photovoltaic and environmental applications.

Abstract:

An efficient photoanode for dye-sensitized solar cells (DSSCs) should have several features, such as high dye uploading, favorable band gaps and good capability in electron transport. Herein, TiO2 nanohexagon arrays (TNHAs) were fabricated by using an electrochemical anodization process. Then, the TNHAs were attached onto FTO glass for front-side illumination mode operation. The as-prepared TiO2 nanohexagon arrays had a length of 27.25 μm and an average diameter of 125 nm. SnO2 is a promising wide band gap material for DSSCs due to its high electron mobility. To improve the performance of DSSCs, SnO2 was introduced into the TNHAs by using a one-step facile immersion approach in 0.25 M K2SnO3 solution for 30 min. The as-fabricated SnO2/TiO2 nanohexagon array heterojunction was utilized as the photoanode for DSSCs. The SnO2 nanoparticles had a superior light harvesting capability owe to the higher surface area for dye uploading and the high electron mobility. The SnO2/TNHAs heterojunction based DSSC had a power conversion efficiency of 6.34%, which was 1.32 times higher than that of the pure TiO2 nanohexagon arrays. Furthermore, incident photon-to-current conversion efficiency (IPCE) and the amount of dye adsorption (Ada) are also improved, with values of 63.96% and 6.8×10-5 mol cm-2, respectively.