Controllable quantum scars induced by spin-orbit couplings in quantum dots.

Spin-orbit couplings (SOCs), originating from the relativistic corrections in the Dirac equation, offer nonlinearity in the classical limit and are capable of driving chaotic dynamics. In a nanoscale quantum dot confined by a two-dimensional parabolic potential with SOCs, various quantum scar states emerge quasi-periodically in the eigenstates of the system, when the ratio of confinement energies in the two directions is nearly commensurable. The scars, displaying both quantum interference and classical trajectory features on the electron density, due to relativistic effects, serve as a bridge between the classical and quantum behaviors of the system.

What is the risk of returning to the emergency department within 30 days for patients diagnosed with substance-induced psychosis?

Objectives: The primary objective of this study was to measure the risk of return Emergency Department (ED) visits in patients presenting to the ED with a diagnosis of substance-induced psychosis. Secondary objectives included: (1) describing the characteristics of patients returning within 30 days to the ED with substance-induced psychosis, and (2) identifying risk factors associated with such ED return.

Methods: At two urban sites from January 1, 2018 to December 31, 2019, we included consecutive patients presenting to the ED with substance-induced psychosis defined by their ED discharge diagnosis of psychosis and clinical evidence of substance use.

One-year mortality of emergency department patients with substance-induced psychosis.

Objectives: Psychosis is a well established complication of non-prescription drug use. We sought to measure the 1-year mortality of emergency department patients with substance-induced psychosis (SIP).

Methods: This study was a multi-centre, retrospective electronic medical records review of patients presenting to the ED with substance-induced psychosis (SIP).

Seeking Maxwell's Demon in a non-reciprocal quantum ring.

A non-reciprocal quantum ring, where one arm of the ring contains the Rashba spin-orbit interaction but not in the other arm, is found to posses very unique electronic properties. In this ring the Aharonov-Bohm oscillations are totally absent. That is because in a magnetic field the electron stays in the non-Rashba arm, while it resides in the Rashba arm for zero (or negative) magnetic field.

Unique Spin Vortices and Topological Charges in Quantum Dots with Spin-orbit Couplings.

Spin textures of one or two electrons in a quantum dot with Rashba or Dresselhaus spin-orbit couplings reveal several intriguing properties. We show here that even at the single-electron level stable spin vortices with tunable topological charges exist. These topological textures appear in the ground state of the dots.

Lipid-based nanocarrier efficiently delivers highly water soluble drug across the blood-brain barrier into brain.

Delivering highly water soluble drugs across blood-brain barrier (BBB) is a crucial challenge for the formulation scientists. A successful therapeutic intervention by developing a suitable drug delivery system may revolutionize treatment across BBB. Efforts were given here to unravel the capability of a newly developed fatty acid combination (stearic acid:oleic acid:palmitic acid = 8.

Interaction-driven distinctive electronic states of artificial atoms at the ZnO interface.

We have investigated the electronic states of planar quantum dots at the ZnO interface containing a few interacting electrons in an externally applied magnetic field. The electron-electron interaction effects are expected to be much stronger in this case than in traditional semiconductor quantum systems, such as in GaAs or InAs quantum dots. In order to highlight that stronger Coulomb effects in the ZnO quantum dots, we have compared the energy spectra and the magnetization in this system to those of the InAs quantum dots.

Irregular Aharonov-Bohm effect for interacting electrons in a ZnO quantum ring.

The electronic states and optical transitions of a ZnO quantum ring containing few interacting electrons in an applied magnetic field are found to be very different from those in a conventional semiconductor system, such as a GaAs ring. The strong Zeeman interaction and the Coulomb interaction of the ZnO system, two important characteristics of the electron system in ZnO, exert a profound influence on the electron states and on the optical properties of the ring. In particular, our results indicate that the Aharonov-Bohm (AB) effect in a ZnO quantum ring strongly depends on the electron number.

Nano-ART and NeuroAIDS.

Human immunodeficiency virus (HIV) is a neurotropic virus that enters the central nervous system (CNS) early in the course of infection. Although highly active antiretroviral therapy (HAART) has resulted in remarkable decline in the morbidity and mortality in AIDS patients, controlling HIV infections still remains a global health priority. HIV access to the CNS serves as the natural viral preserve because most antiretroviral (ARV) drugs possess inadequate or zero delivery across the brain barriers.

Excitation gap of fractal quantum hall states in graphene.

In the presence of a magnetic field and an external periodic potential the Landau level spectrum of a two-dimensional electron gas exhibits a fractal pattern in the energy spectrum which is described as the Hofstadter's butterfly. In this work, we develop a Hartree-Fock theory to deal with the electron-electron interaction in the Hofstadter's butterfly state in a finite-size graphene with periodic boundary conditions, where we include both spin and valley degrees of freedom. We then treat the butterfly state as an electron crystal so that we could obtain the order parameters of the crystal in the momentum space and also in an infinite sample.

Fractional quantum Hall effect in Hofstadter butterflies of Dirac fermions.

We report on the influence of a periodic potential on the fractional quantum Hall effect (FQHE) states in monolayer graphene. We have shown that for two values of the magnetic flux per unit cell (one-half and one-third flux quantum) an increase of the periodic potential strength results in a closure of the FQHE gap and appearance of gaps due to the periodic potential. In the case of one-half flux quantum this causes a change of the ground state and consequently the change of the momentum of the system in the ground state.

Tunable spin-selective transport through DNA with mismatched base pairs.

In our theoretical analysis of spin-selective transport through a homogeneous poly(G)-poly(C) DNA we explore the influence of a mismatched base pair in the DNA chain. The spin polarization of the electrical current through DNA is strongly sensitive to the presence of the mispair in a DNA with less than 20 base pairs. Replacing a canonical G-C base pair by a G-A mispair in homogeneous DNA can strongly decrease, increase up to an order of magnitude, or even change the sign of spin polarization of the electrical current.

Gap structure of the Hofstadter system of interacting Dirac fermions in graphene.

The effects of mutual Coulomb interactions between Dirac fermions in monolayer graphene on the Hofstadter energy spectrum are investigated. For two flux quanta per unit cell of the periodic potential, interactions open a gap in each Landau level with the smallest gap in the n=1 Landau level. For more flux quanta through the unit cell, where the noninteracting energy spectra have many gaps in each Landau level, interactions enhance the low-energy gaps and strongly suppress the high-energy gaps and almost close a high-energy gap for n=1.

Stable Pfaffian state in bilayer graphene.

Here, we show that the incompressible Pfaffian state originally proposed for the 5/2 fractional quantum Hall states in conventional two-dimensional electron systems can actually be found in a bilayer graphene at one of the Landau levels. The properties and stability of the Pfaffian state at this special Landau level strongly depend on the magnetic field strength. The graphene system shows a transition from the incompressible to a compressible state with increasing magnetic field.

Interacting dirac fermions on a topological insulator in a magnetic field.

We study the fractional quantum Hall states on the surface of a topological insulator thin film in an external magnetic field, where the Dirac fermion nature of the charge carriers have been experimentally established only recently. Our studies indicate that the fractional quantum Hall states should indeed be observable in the surface Landau levels of a topological insulator. The strength of the effect will however be different, compared to that in graphene, due to the finite thickness of the topological insulator film and due to the admixture of Landau levels of the two surfaces of the film.

Intramolecularly coordinated azobenzene selenium derivatives: effect of strength of the Se···N intramolecular interaction on luminescence.

A series of selenium derivatives (6-12) of 2-phenylazophenyl have been synthesized using o-lithiation route. The effect of the strength of the intramolecular Se···N interaction on the absorption spectra as well as emission spectra has been studied. The studies suggest that the secondary bonding Se···N interaction give rise to fluorescence, however, the strength of Se···N interaction cannot be directly correlated with the intensity of the fluorescence.

Irradiated bilayer graphene.

We describe the gated bilayer graphene system when it is subjected to intense terahertz frequency electromagnetic radiation. We examine the electron band structure and density of states via exact diagonalization methods within Floquet theory. We find that dynamical states are induced which lead to modification of the band structure.

Quantum transport anomalies in DNA containing mispairs.

The effect of mispairs on charge transport in DNA of sequence (GC)(TA)(N)(GC)(3) connected to platinum electrodes is studied using the tight-binding model. With parameters derived from an ab initio density functional result, we calculate the current versus bias voltage for DNA with and without a mispair and for different numbers of (TA) basepairs N between the single and triple (GC) basepairs. The current decays exponentially with N under low bias but reaches a minimum under high bias when a multichannel transport mechanism is established.

Controllable driven phase transitions in fractional quantum Hall states in bilayer graphene.

Here we report from our theoretical studies that, in biased bilayer graphene, one can induce phase transitions from an incompressible fractional quantum Hall state to a compressible state by tuning the band gap at a given electron density. The nature of such phase transitions is different for weak and strong interlayer coupling. Although for strong coupling more levels interact there is a lesser number of transitions than for the weak coupling case.

Isolation and reactivity of an unusually stable organoselenenyl azide.

The stabilities of a series of isolated covalent selenium(II) azides such as [2-[1-(3,5-dimethylphenyl)-2-naphthyl]-4,5-dihydro-4,4-dimethyloxazole]selenium azide (2a), [2-(4,4-dimethyl-2-oxazolinyl)phenyl]selenenyl azide (3a), [o-(2,6-diisopropylphenyl-iminomethinyl)phenyl]selenenyl azide (4a), [o-(R)-(methylbenzyliminomethinyl)phenyl]selenenyl azide (5a) and o-formylphenylselenenyl azide (6a) are rationalized; also the reactivity of first room temperature stable azide (2a) toward 1,3-cycloaddition has been explored.

Spin interactions in a quantum dot containing a magnetic impurity.

The electron and hole states in a CdTe quantum dot containing a single magnetic impurity in an external magnetic field are investigated using a multiband approximation which includes the heavy hole-light hole coupling effects. The electron-hole spin interactions and sp-d interactions between the electron, the hole and the magnetic impurity are also included. The exciton energy levels and optical transitions are evaluated using the exact diagonalization scheme.

Sustained ferromagnetism induced by H-vacancies in graphane.

The electronic and magnetic properties of graphane flakes with H-vacancies were investigated using quantum-chemistry methods. The hybridization of the edges is found to be absolutely crucial in defining the size of the HOMO-LUMO gap, which is increased from 3.04 to 7.

Electrical current through DNA containing mismatched base pairs.

Mismatched base pairs, such as different conformations of the G.A mispair, cause only minor structural changes in the host DNA molecule, thereby making mispair recognition an arduous task. Electron transport in DNA that depends strongly on the hopping transfer integrals between the nearest base pairs, which in turn are affected by the presence of a mispair, might be an attractive approach in this regard.

Unique magnetic signatures of mismatched base pairs in DNA.

Magnetic properties of DNA containing mispairs, such as different conformations of the GA mispair, or a GT mispair inserted into the DNA chain, have been theoretically investigated. The essential ingredients for these studies, the charge transfer integrals, were evaluated from the DNA sequences containing the mispair and optimized in the solvent. We find that the magnetic susceptibilities of the host DNA chain containing a large number of Watson-Crick base pairs are significantly altered in the presence of the mispairs, and the effects depend on the choice of mispairs.

Long-range Coulomb interaction in bilayer graphene.

We report on our studies of interacting electrons in bilayer graphene in a magnetic field. We demonstrate that the long-range Coulomb interactions between electrons in this material are highly important and account for the band asymmetry in recent optical magneto-absorption experiments [E. A.