Tasaki H.,Gakushuin University
Physical Review Letters | Year: 2013
In a system of interacting f=1 bosons (in the subspace where the total spin in the z direction is vanishing), we prove inequalities for the ground state expectation value of the density of spin-0 bosons. The inequalities imply that the ground state possesses "polar" or "antiferromagnetic" order when the quadratic Zeeman term q is large enough. In the low density limit, the inequalities establish the existence of a sharp transition at q=0 when q is varied. © 2013 American Physical Society.
Nakano F.,Gakushuin University
Journal of Statistical Physics | Year: 2014
We study the level statistics for two classes of 1-dimensional random Schrödinger operators: (1) for operators whose coupling constants decay as the system size becomes large, and (2) for operators with critically decaying random potential. As a byproduct of (2) with our previous result (Kotani and Nakano in Festschrift Masatoshi Fukushima, 2013) imply the coincidence of the limits of circular and Gaussian beta ensembles. © 2014 Springer Science+Business Media New York.
Sun K.,University of Maryland University College |
Gu Z.,University of California at Santa Barbara |
Katsura H.,Gakushuin University |
Das Sarma S.,University of Maryland University College
Physical Review Letters | Year: 2011
We report the theoretical discovery of a class of 2D tight-binding models containing nearly flatbands with nonzero Chern numbers. In contrast with previous studies, where nonlocal hoppings are usually required, the Hamiltonians of our models only require short-range hopping and have the potential to be realized in cold atomic gases. Because of the similarity with 2D continuum Landau levels, these topologically nontrivial nearly flatbands may lead to the realization of fractional anomalous quantum Hall states and fractional topological insulators in real materials. Among the models we discover, the most interesting and practical one is a square-lattice three-band model which has only nearest-neighbor hopping. To understand better the physics underlying the topological flatband aspects, we also present the studies of a minimal two-band model on the checkerboard lattice. © 2011 American Physical Society.
Nakamura H.,Gakushuin University
Future Medicinal Chemistry | Year: 2013
Recent development of boron cluster lipids and their liposomal boron delivery system (BDS) are summarized in this article. Boron compounds used in boron neutron capture therapy (BNCT) are, in general, nontoxic unless neutron capture reaction of boron takes place. Therefore, the boron compounds accumulated into other organs would not cause such side effects for patient. Selective and sufficient delivery of boron-10 to tumor results in the successful BNCT. There are two approaches for BDS: encapsulation of boron compounds into liposomes and incorporation of boron-conjugated lipids into the liposomal bilayer, both of which have been significantly investigated. The combination of both approaches displayed potency and, hence, the ability to reduce the total dose of liposomes without reducing the efficacy of BNCT. Boron compounds that have no affinity to tumor can potentially be delivered to tumor tissues by liposomes, therefore, liposomal BDS would be one of the most attractive approaches for efficient BNCT of various cancers. © 2013 Future Science Ltd.
Sato S.,Gakushuin University |
Nakamura H.,Gakushuin University
Angewandte Chemie - International Edition | Year: 2013
A photocatalyst ([Ru(bpy)3]2+) bound to a protein ligand was essential for the title method. Local single-electron transfer from the catalyst resulted in the formation of tyrosyl radicals. N′-Acetyl-N,N- dimethyl-1,4-phenylenediamine was used as the tyrosyl radical trapping agent and used in a radical addition to afford selective modification of the target protein. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.