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.

Effect of Copper Doping on Electronic Structure, Geometric Structure, and Stability of Thiolate-Protected Au25 Nanoclusters.

Abstract: Several recent studies have attempted to impart [Au25(SR)18](-) with new properties by doping with foreign atoms. In this study, we studied the effect of copper doping on the electronic structure, geometric structure, and stability of [Au25(SR)18](-) with the aim of investigating the effect of foreign atom doping of [Au25(SR)18](-). CunAu25-n(SC2H4Ph)18 was synthesized by reducing complexes formed by the reaction between metal salts (copper and gold salts) and PhC2H4SH with NaBH4. Mass analysis revealed that the products contained CunAu25-n(SC2H4Ph)18 (n = 1-5) in high purity. Experimental and theoretical analysis of the synthesized clusters revealed that copper doping alters the optical properties and redox potentials of the cluster, greatly distorts its geometric structure, and reduces the cluster stability in solution. These findings are expected to be useful for developing design guidelines for functionalizing [Au25(SR)18](-) through doping with foreign atoms.

The Arabidopsis Phosphatidylinositol Phosphate 5-Kinase PIP5K3 is a key regulator of root hair tip growth

Abstract: Phosphatidylinositol 4,5-bisphosphate [PtdIns(4,5)P2] functions as a site-specific signal on membranes to promote cytoskeletal reorganization and membrane trafficking. Localization of PtdIns(4,5)P2 to apices of growing root hairs and pollen tubes suggests that it plays an important role in tip growth. However, its regulation and mode of action remain unclear. We found that Arabidopsis thaliana PIP5K3 (for Phosphatidylinositol Phosphate 5-Kinase 3) encodes a phosphatidylinositol 4-phosphate 5-kinase, a key enzyme producing PtdIns(4,5)P2, that is preferentially expressed in growing root hairs. T-DNA insertion mutations that substantially reduced the expression of PIP5K3 caused significantly shorter root hairs than in the wild type. By contrast, overexpression caused longer root hairs and multiple protruding sites on a single trichoblast. A yellow fluorescent protein (YFP) fusion of PIP5K3, driven by the PIP5K3 promoter, complemented the short-root-hair phenotype. PIP5K3-YFP localized to the plasma membrane and cytoplasmic space of elongating root hair apices, to growing root hair bulges, and, notably, to sites about to form root hair bulges. The signal was greatest in rapidly growing root hairs and quickly disappeared when elongation ceased. These results provide evidence that PIP5K3 is involved in localizing PtdIns(4,5)P2 to the elongating root hair apex and is a key regulator of the machinery that initiates and promotes root hair tip growth.

Scalaron from R 2 -gravity as a heavy field

Abstract: We study a model of inflation in which a scalar field χ is non-minimally coupled to Starobinsky's R2 gravity. After transforming it to the Einstein frame, a new scalar field, the scalaron , will appear and couple to χ with a nontrivial field metric, while χ acquires a positive mass via the non-minimal coupling. Initially inflation occurs along the direction with χ trapped near its origin by this induced mass. After crosses a critical value, it starts rolling down rapidly and proceeds to damped oscillations around an effective local minimum determined by the value of χ, while inflation still continues, driven by the χ field at this second stage where the effect of the non-minimal coupling becomes negligible. The presence of the damped oscillations during the transition from the first to second stage of inflation causes enhancement and oscillation features in the power spectrum of the curvature perturbation. Assuming that the oscillations may be treated perturbatively, we calculate these features by using the δ N formalism, and discuss its observational implications to large scale CMB anomalies or primordial black hole formation, depending on the scale of the features.

Comparative Study of Sodium Polyacrylate and Poly(vinylidene fluoride) as Binders for High Capacity Si–Graphite Composite Negative Electrodes in Li-Ion Batteries

Abstract: To study the effect of different polymer binders on electrochemical performance of the Si composite electrode in rechargeable lithium-ion batteries, sodium polyacrylate (PAANa), sodium carboxymethyl cellulose (CMCNa), and poly(vinylidene fluoride) (PVdF) are utilized as the polymer binders for the preparation of composite electrodes consisting of powdery silicon, graphite, and Ketjen black. The electrodes are examined by cross-sectional observation using a scanning electron microscope after a focused ion beam process, X-ray photoelectron spectroscopy, micro Raman spectroscopy, X-ray diffraction, and a peel test. We report that electrode performance of the Si composites depends on a selection of binders, and PAANa binder remarkably improves the electrochemical lithiation and delithiation performance of the Si–graphite composite electrode compared to that of conventional binders of PVdF and CMCNa. When the electrode is prepared with 30 wt % PAANa binder, the higher initial efficiency is obtained with much i...