Relativistic Hamiltonian for Neutral Atom of Spin-1/2 Nucleus in Homogeneous Magnetic Field

A relativistic formalism to construct the Hamiltonian for a general N-electron neutral atom with a spin-1/2 nucleus and placed in a homogeneous magnetic field [J. Chem. Phys. 123 064101 (2005)] is discussed here. Projected Coulomb and Breit interactions are taken to describe the inter-particle interaction through second order in fine structure constant. The center of mass motion is separated from the movement of the neutral (N+1) fermion system. Using a series of suitable unitary transformations, the Hamiltonian can be brought into a separable form. The correct atomic Hamiltonian in the non-relativistic limit is also discussed. The treatment can be extended to the case of a molecule containing atoms of only spin-1/2 nuclei

Minimally Kekulenoid π-Networks and Reactivity for Acyclics

Graphs which admit exactly one Kekule structure are here termed »minimally Kekulenoid« and are suggested to be an interesting class of conjugated π-network structures, which then are investigated, especially for the alternant case. The inverses of the adjacency matrices of such molecular graphs are constructed, and found to represent a (generally edge-weighted) adjacency matrix of a »Kekulenoid transform« graph. These transforms are also studied, and a »multiplicative « pairing result is established for suitable circumstances. It is noted that tree graphs are either non-Kekulenoid or minimally Kekulenoid, and for the minimally Kekulenoid case the »Kekulenoid transform« are shown to be especially simple. Finally bounds for the HOMO-LUMO gap of tree graphs (representing acyclic conjugated polyenes) are obtained in terms of chemically appealing »conjugated-path« invariants. Some examples are presented, and some general chemical consequences relating to »cross conjugation« are identified

Constraining Scalar Leptoquarks from the K and B Sectors

Upper bounds at the weak scale are obtained for all $\lambda_{ij}\lambda_{im}$ type product couplings of the scalar leptoquark model which may affect K-K(bar), B_d-B_d(bar), and B_s-B_s(bar)$ mixing, as well as leptonic and semileptonic K and B decays. Constraints are obtained for both real and imaginary parts of the couplings. We also discuss the role of leptoquarks in explaining the anomalously large CP-violating phase in B_s-B_s(bar) mixing.Comment: 16 pages, 5 figures, more constraints analyzed, added a number of reference

Fast loading of a cold mixture of Sodium and Potassium atoms from compact and versatile cold atomic beam sources

We present the design, implementation and detailed experimental characterization of two-dimensional Magneto-optical traps (MOT) of bosonic $^{23}$Na and $^{39}$K atoms for loading the cold atomic mixture in a dual-species 3DMOT with a large number of atoms. We report our various measurements pertaining to the characterisation of the two 2D$^+$MOTs via the capture rate in the 3DMOT and also present the optimised parameters for the best performance of the system of the cold atomic mixture. In the optimised condition, we capture more than $3 \times 10^{10}$ $^{39}$K atoms and $5.8 \times 10^8$ $^{23}$Na atoms in the 3DMOT simultaneously from the individual 2D$^+$MOTs with the capture rate of $5 \times 10^{10}$ atoms/sec and $3.5 \times 10^8$ atoms/sec for $^{39}$K and $^{23}$Na, respectively. We also demonstrate improvements of more than a factor of 5 in the capture rate into the 3DMOT from the cold atomic sources when a relatively high-power ultra-violet light is used to cause light-induced atomic desorption (LIAD) in the 2D$^+$MOT glass cells. The cold atomic mixture would be useful for further experiments on Quantum simulation with ultra-cold quantum mixtures in optical potentials

Vertically Aligned Few-Layered Graphene-Based Non-Cryogenic Bolometer

In this study, we report the photoresponse of vertically aligned few-layered graphene (VAG) upon infra-red (IR) irradiation at room temperature. Four probe measurements showed the current−voltage (I−V) characteristic of electrical switching during pulsed IR irradiation. The photoresponse reported here for VAG was significantly higher than that reported for carbon nanotube (CNT) samples. Our investigation shows that such a photoresponse arose solely from the bolometric effect, where the conductivity changed with temperature. The resistance magnitude of the VAGs increased ~two fold for each 6 °C increase in temperature. Also, the Thermal Coefficient of Resistance (TCR) in this region was ~11%/K, which is the highest TCR value reported for any carbon nanomaterial

Abrogated Inflammatory Response Promotes Neurogenesis in a Murine Model of Japanese Encephalitis

Japanese encephalitis virus (JEV) induces neuroinflammation with typical features of viral encephalitis, including inflammatory cell infiltration, activation of microglia, and neuronal degeneration. The detrimental effects of inflammation on neurogenesis have been reported in various models of acute and chronic inflammation. We investigated whether JEV-induced inflammation has similar adverse effects on neurogenesis and whether those effects can be reversed using an anti-inflammatory compound minocycline.Here, using in vitro studies and mouse models, we observed that an acute inflammatory milieu is created in the subventricular neurogenic niche following Japanese encephalitis (JE) and a resultant impairment in neurogenesis occurs, which can be reversed with minocycline treatment. Immunohistological studies showed that proliferating cells were replenished and the population of migrating neuroblasts was restored in the niche following minocycline treatment. In vitro, we checked for the efficacy of minocycline as an anti-inflammatory compound and cytokine bead array showed that production of cyto/chemokines decreased in JEV-activated BV2 cells. Furthermore, mouse neurospheres grown in the conditioned media from JEV-activated microglia exhibit arrest in both proliferation and differentiation of the spheres compared to conditioned media from control microglia. These effects were completely reversed when conditioned media from JEV-activated and minocycline treated microglia was used.This study provides conclusive evidence that JEV-activated microglia and the resultant inflammatory molecules are anti-proliferative and anti-neurogenic for NSPCs growth and development, and therefore contribute to the viral neuropathogenesis. The role of minocycline in restoring neurogenesis may implicate enhanced neuronal repair and attenuation of the neuropsychiatric sequelae in JE survivors