Tokyo University of Science

About: Tokyo University of Science is a education organization based out in Tokyo, Japan. It is known for research contribution in the topics: Thin film & Enantioselective synthesis. The organization has 15800 authors who have published 24147 publications receiving 438081 citations. The organization is also known as: Tōkyō Rika Daigaku & Science University of Tokyo.

Effects of graft densities and chain lengths on separation of bioactive compounds by nanolayered thermoresponsive Polymer brush surfaces

Abstract: We have prepared various poly(N-isopropylacrylamide) (PIPAAm)-grafted silica bead surfaces through surface-initiated atom transfer radical polymerization (ATRP) by changing graft densities and brush chain lengths. The prepared surfaces were characterized by chromatographic analysis using the modified silica beads as chromatographic stationary phases. ATRP initiator (2-(m,p-chloromethylphenyl)ethyltrichlorosilane) density on silica bead surfaces was modulated by changing the feed composition of the self-assembled monolayers (SAMs) of mixed silane coupling agents consisting of ATRP initiator and phenethyltrichlorosilane on the surfaces. IPAAm was then polymerized on SAM-modified silica bead surfaces by ATRP in 2-propanol at 25 °C. The chain length of the grafted PIPAAm was controlled by simply changing the ATRP reaction time at constant catalyst concentration. The thermoresponsive surface properties of the PIPAAm-grafted silica beads were investigated by temperature-dependent elution behavior of hydrophobic...

Two-photon probe of the Jaynes–Cummings model and controlled symmetry breaking in circuit QED

Abstract: Micrometre-scale superconducting circuits can act as quantum two-level systems, but unlike in their natural counterparts—such as atoms—the parameters of these ‘artificial qubits’ can be controlled externally. This tunability has now been used to break the symmetry of the system hamiltonian in a controlled manner. Superconducting qubits1,2 behave as artificial two-level atoms and are used to investigate fundamental quantum phenomena. In this context, the study of multiphoton excitations3,4,5,6,7 occupies an important role. Moreover, coupling superconducting qubits to onchip microwave resonators has given rise to the field of circuit quantum electrodynamics8,9,10,11,12,13,14,15 (QED). In contrast to quantum-optical cavity QED (refs 16, 17, 18, 19), circuit QED offers the tunability inherent to solid-state circuits. Here, we report on the observation of key signatures of a two-photon-driven Jaynes–Cummings model, which unveils the upconversion dynamics of a superconducting flux qubit20 coupled to an on-chip resonator. Our experiment and theoretical analysis show clear evidence for the coexistence of one- and two-photon-driven level anticrossings of the qubit–resonator system. This results from the controlled symmetry breaking of the system hamiltonian, causing parity to become a not-well-defined property21. Our study provides fundamental insight into the interplay of multiphoton processes and symmetries in a qubit–resonator system.

Chaotic inflation in modified gravitational theories

Abstract: We study chaotic inflation in the context of modified gravitational theories. Our analysis covers models based on (i) a field coupling ?() with the kinetic energy X = ?(1/2)g?????? and a nonmimimal coupling ?2R/2 with a Ricci scalar R, (ii) Brans-Dicke (BD) theories, (iii) Gauss-Bonnet (GB) gravity, and (iv) gravity with a Galileon correction. Dilatonic coupling with the kinetic energy and/or negative nonminimal coupling are shown to lead to compatibility with observations of the Cosmic Microwave Background (CMB) temperature anisotropies for the self-coupling inflaton potential V() = ?4/4. BD theory with a quadratic inflaton potential, which covers Starobinsky's f(R) model f(R) = R+R2/(6M2) with the BD parameter ?BD = 0, gives rise to a smaller tensor-to-scalar ratio for decreasing ?BD. In the presence of a GB term coupled to the field , we express the scalar/tensor spectral indices ns and nt as well as the tensor-to-scalar ratio r in terms of two slow-roll parameters and place bounds on the strength of the GB coupling from the joint data analysis of WMAP 7yr combined with other observations. We also study the Galileon-like self-interaction ?()X with exponential coupling ?()e?. Using a CMB likelihood analysis we put bounds on the strength of the Galileon coupling and show that the self coupling potential can in fact be made compatible with observations in the presence of the exponential coupling with ? > 0.