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PHOTON-ASSISTED TRANSPORT CHARACTERISTICS THROUGH QUANTUM DOT COUPLED TO SUPERCONDUCTING RESERVOIRS
A. H. PHILLIPS,A. S. ATALLAH,A. F. AMIN,M. A. SEMARY 성균관대학교(자연과학캠퍼스) 성균나노과학기술원 2006 NANO Vol.1 No.3
The influence of time-varying fields on the transport through a mesoscopic device has been investigated. This mesoscopic device is modeled as a quantum dot coupled to superconducting reservoirs via quantum point contact. The effect of a magnetic field and the Andreev reflection process were taken into account. The conductance was deduced by using Landuaer–Buttiker equation. A numerical calculation has been performed that shows a resonant tunneling behavior. Such investigation is important for fabricating photoelectron mesoscopic devices.
Thermoelectric Seebeck and Peltier effects of single walled carbon nanotube quantum dot nanodevice
H. A. El-Demsisy,M. D. Asham,D. S. Louis,A. H. Phillips 한국탄소학회 2017 Carbon Letters Vol.21 No.-
The thermoelectric Seebeck and Peltier effects of a single walled carbon nanotube (SWCNT) quantum dot nanodevice are investigated, taking into consideration a certain value of applied tensile strain and induced ac-field with frequency in the terahertz (THz) range. This device is modeled as a SWCNT quantum dot connected to metallic leads. These two metallic leads operate as a source and a drain. In this three-terminal device, the conducting substance is the gate electrode. Another metallic gate is used to govern the electrostatics and the switching of the carbon nanotube channel. The substances at the carbon nanotube quantum dot/ metal contact are controlled by the back gate. Results show that both the Seebeck and Peltier coefficients have random oscillation as a function of gate voltage in the Coulomb blockade regime for all types of SWCNT quantum dots. Also, the values of both the Seebeck and Peltier coefficients are enhanced, mainly due to the induced tensile strain. Results show that the three types of SWCNT quantum dot are good thermoelectric nanodevices for energy harvesting (Seebeck effect) and good coolers for nanoelectronic devices (Peltier effect).
High-resolution tunnelling spectroscopy of a graphene quartet
Song, Young Jae,Otte, Alexander F.,Kuk, Young,Hu, Yike,Torrance, David B.,First, Phillip N.,de Heer, Walt A.,Min, Hongki,Adam, Shaffique,Stiles, Mark D.,MacDonald, Allan H.,Stroscio, Joseph A. Nature Publishing Group, a division of Macmillan P 2010 Nature Vol.467 No.7312
Electrons in a single sheet of graphene behave quite differently from those in traditional two-dimensional electron systems. Like massless relativistic particles, they have linear dispersion and chiral eigenstates. Furthermore, two sets of electrons centred at different points in reciprocal space (??valleys??) have this dispersion, giving rise to valley degeneracy. The symmetry between valleys, together with spin symmetry, leads to a fourfold quartet degeneracy of the Landau levels, observed as peaks in the density of states produced by an applied magnetic field. Recent electron transport measurements have observed the lifting of the fourfold degeneracy in very large applied magnetic fields, separating the quartet into integer and, more recently, fractional levels. The exact nature of the broken-symmetry states that form within the Landau levels and lift these degeneracies is unclear at present and is a topic of intense theoretical debate. Here we study the detailed features of the four quantum states that make up a degenerate graphene Landau level. We use high-resolution scanning tunnelling spectroscopy at temperatures as low as 10??mK in an applied magnetic field to study the top layer of multilayer epitaxial graphene. When the Fermi level lies inside the fourfold Landau manifold, significant electron correlation effects result in an enhanced valley splitting for even filling factors, and an enhanced electron spin splitting for odd filling factors. Most unexpectedly, we observe states with Landau level filling factors of 7/2, 9/2 and 11/2, suggestive of new many-body states in graphene.
SPIN-COHERENT TRANSPORT IN MESOSCOPIC INTERFERENCE DEVICE
WALID A. ZEIN,ADEL H. PHILLIPS,OMAR A. OMAR 성균관대학교(자연과학캠퍼스) 성균나노과학기술원 2007 NANO Vol.2 No.6
We investigate the quantum size effect in the phase coherent mesoscopic ring. A quantum dot is embedded in one arm and it is connected to one lead via tunnel barrier. Both Aharonov–Casher and Aharonov–Bohm effects are studied. A spin-dependent conductance has been deduced and it depends on the intrinsic parameters. Our results show that the strength of spin-orbit coupling depends on the size of the present device. This investigation is valuable for fabricating such spintronics devices.
Kim, Chunjoong,Adil, Abdullah A.,Bayliss, Ryan D.,Kinnibrugh, Tiffany L.,Lapidus, Saul H.,Nolis, Gene M.,Freeland, John W.,Phillips, Patrick J.,Yi, Tanghong,Yoo, Hyun Deog,Kwon, Bob Jin,Yu, Young-Sang American Chemical Society 2018 Chemistry of materials Vol.30 No.5
<P>Oxides undergoing reversible electrochemical cycling of Mg<SUP>2+</SUP> ions would enable novel battery concepts beyond Li<SUP>+</SUP>, capable of storing large amounts of energy. However, materials showing this chemical reactivity are scarce. Suitable candidates require small particles to shorten transport lengths, together with chemically complex structures that promote cation mobility, such as spinel. These goals pose a challenge for materials chemists. Here, nanocrystals of spinel-type Mg<SUB>0.5</SUB>Mn<SUB>2.5</SUB>O<SUB>4</SUB> were prepared using colloidal synthesis, and their electrochemical activity is presented. Cycling in an aqueous Mg<SUP>2+</SUP> electrolyte led to a reversible transformation between a reduced spinel and an oxidized layered framework. This reaction involves large amounts of capacity because of the full oxidation to Mn<SUP>4+</SUP>, through the extraction of both Mg<SUP>2+</SUP> and, in the first cycle, Mn<SUP>2+</SUP> ions. Re-formation of the spinel upon reduction resulted in enrichment with Mg<SUP>2+</SUP>, indicating that its insertion is more favorable than that of Mn<SUP>2+</SUP>. Incorporation of water into the structure was not indispensable for the transformation, as revealed by experiments in non-aqueous electrolytes and infrared spectroscopy. The findings open the door for the use of similar nanocrystals in Mg batteries provided that electrolytes with suitable anodic stability are discovered, thereby identifying novel routes toward electrode materials for batteries with high energy.</P> [FIG OMISSION]</BR>
Sex and Gender Influence Urinary Symptoms and Management in Multiple System Atrophy
Elke Schipani Bailey,Sara J. Hooshmand,Negin Badihian,Paola Sandroni,Eduardo E. Benarroch,James H. Bower,Phillip A. Low,Wolfgang Singer,Elizabeth A. Coon 대한파킨슨병및이상운동질환학회 2023 Journal Of Movement Disorders Vol.16 No.2
Multiple system atrophy (MSA) is characterized by urinary dysfunction, yet the influence of sex and gender on urinary symptoms and treatment is unclear. We sought to characterize sex and gender differences in the symptomatology, evaluation, and management of urinary dysfunction in patients with MSA.