239 research outputs found
Superfluid-Insulator transition of two-species bosons with spin-orbit coupling
Motivated by recent experiments [Y.J. Lin {\it et al.}, Nature {\bf 471}, 83
(2011)], we study Mott phases and superfluid-insulator (SI) transitions of
two-species ultracold bosonic atoms in a two-dimensional square optical lattice
with nearest neighbor hopping amplitude in the presence of a spin-orbit
coupling characterized by a tunable strength . Using both
strong-coupling expansion and Gutzwiller mean-field theory, we chart out the
phase diagrams of the bosons in the presence of such spin-orbit interaction. We
compute the momentum distribution of the bosons in the Mott phase near the SI
transition point and show that it displays precursor peaks whose position in
the Brillouin zone can be varied by tuning . Our analysis of the
critical theory of the transition unravels the presence of unconventional
quantum critical points at which are accompanied by emergence of
an additional gapless mode in the critical region. We also study the superfluid
phases of the bosons near the SI transition using a Gutzwiller mean-field
theory which reveals the existence of a twisted superfluid phase with an
anisotropic twist angle which depends on . Finally, we compute the
collective modes of the bosons and point out the presence of reentrant SI
transitions as a function of for non-zero . We propose experiments
to test our theory.Comment: v2, 13 pages, 9 figs; new section and fig
Synthesis, Characterization, DNA binding and Microbial Activity of Cobalt (III) Complexes of Mixed Ligands, Hydroxamic Acid and 1,10-Phenanthroline
New Co(III) complexes of mixed ligands, hydroxamic acid (L1 = AHA (acetohydroxamic acid), L2 = BHA (benzohydroxamic acid) and L3 = OHA (oxalohydroxamic acid) and 1, 10-phenanthroline (phen) were synthesized and characterized by NMR, IR, UV-visible, mass spectrometer, and elemental analysis. In the complexes, [Co(phen)2L]ClO4 (L = L1, L2, L3), the metal ion is coordinated by six atoms, two oxygen atoms from hydroxamic acid and 4N atoms from co-ligand 1, 10-phenanthroline to form octahedral Co(III) complexes. The interaction of these complexes with calf thymus DNA (CT-DNA) has been investigated by absorption spectroscopy measurement. The DNA-binding constants for complexes 1, 2, 3 are 2.47 x 106 M-1, 4.02 x 106 M-1, 2.23 x 106 M-1 respectively. Detailed analysis shows that these complexes bind with DNA through interaction binding. And the study of microbial activity against Gram positive and Gram negative bacteria. Keywords: DNA binding, hydroxamic acid, cobalt complexes, 1, 10-phenanthroline, microbial activity
Protein Nanoparticles as Vaccine Platforms for Human and Zoonotic Viruses
Vaccines are one of the most effective medical interventions, playing a pivotal role in treating infectious diseases. Although traditional vaccines comprise killed, inactivated, or liveattenuated pathogens that have resulted in protective immune responses, the negative consequences of their administration have been well appreciated. Modern vaccines have evolved to contain purified antigenic subunits, epitopes, or antigen-encoding mRNAs, rendering them relatively safe. However, reduced humoral and cellular responses pose major challenges to these subunit vaccines. Protein nanoparticle (PNP)-based vaccines have garnered substantial interest in recent years for their ability to present a repetitive array of antigens for improving immunogenicity and enhancing protective responses. Discovery and characterisation of naturally occurring PNPs from various living organisms such as bacteria, archaea, viruses, insects, and eukaryotes, as well as computationally designed structures and approaches to link antigens to the PNPs, have paved the way for unprecedented advances in the field of vaccine technology. In this review, we focus on some of the widely used naturally occurring and optimally designed PNPs for their suitability as promising vaccine platforms for displaying native-like antigens from human viral pathogens for protective immune responses. Such platforms hold great promise in combating emerging and re-emerging infectious viral diseases and enhancing vaccine efficacy and safety
Differential rates of perinatal maturation of human primary and nonprimary auditory cortex
Abstract Primary and nonprimary cerebral cortex mature along different timescales; however, the differences between the rates of maturation of primary and nonprimary cortex are unclear. Cortical maturation can be measured through changes in tissue microstructure detectable by diffusion magnetic resonance imaging (MRI). In this study, diffusion tensor imaging (DTI) was used to characterize the maturation of Heschl’s gyrus (HG), which contains both primary auditory cortex (pAC) and nonprimary auditory cortex (nAC), in 90 preterm infants between 26 and 42 weeks postmenstrual age (PMA). The preterm infants were in different acoustical environments during their hospitalization: 46 in open ward beds and 44 in single rooms. A control group consisted of 15 term-born infants. Diffusion parameters revealed that (1) changes in cortical microstructure that accompany cortical maturation had largely already occurred in pAC by 28 weeks PMA, and (2) rapid changes were taking place in nAC between 26 and 42 weeks PMA. At term equivalent PMA, diffusion parameters for auditory cortex were different between preterm infants and term control infants, reflecting either delayed maturation or injury. No effect of room type was observed. For the preterm group, disturbed maturation of nonprimary (but not primary) auditory cortex was associated with poorer language performance at age two years
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