Tokyo Institute of Technology

About: Tokyo Institute of Technology is a education organization based out in Tokyo, Tôkyô, Japan. It is known for research contribution in the topics: Catalysis & Thin film. The organization has 46775 authors who have published 101656 publications receiving 2357893 citations. The organization is also known as: Tokyo Tech & Tokodai.

Results from one thousand days of real-time, directional solar-neutrino data.

Abstract: A data sample of 1040 days from the Kamiokande II detector, consisting of subsamples of 450 days at electron-energy threshold ${\mathit{E}}_{\mathit{e}}$\ensuremath{\ge}9.3 MeV and 590 days at ${\mathit{E}}_{\mathit{e}}$\ensuremath{\ge}7.5 MeV, yields a clear directional correlation of the solar-neutrino-induced electron events with respect to the Sun and a measurement of the differential electron-energy distribution. These provide unequivocal evidence for the production of $^{8}\mathrm{B}$ by fusion in the Sun. The measured flux of $^{8}\mathrm{B}$ solar neutrinos from the two subsamples relative to a prediction of the standard solar model is 0.46\ifmmode\pm\else\textpm\fi{}0.05(stat)\ifmmode\pm\else\textpm\fi{}0.06(syst). The total data sample is tested for short-term time variation; within the statistical error, no significant variation is observed.

Carbazole Dendrimers as Solution‐Processable Thermally Activated Delayed‐Fluorescence Materials

Abstract: Recently, thermally activated delayed fluorescence (TADF) materials have received increasing attention as effective emitters for organic light-emitting diodes (OLEDs). However, most of them are usually employed as dopants in a host material. In this report, carbazole dendrimers with a triphenyl-s-triazine core are reported, which are the first solution-processable, non-doped, high-molecular-weight TADF materials. The dendrimers were obtained by a new and facile synthetic route using the tert-butyldimethylsilyl moiety as a protecting group. All dendrimers showed TADF in toluene. Measurements of the temperature-dependent luminescence lifetime revealed that spin-coated neat films also showed TADF with moderate quantum yields. OLED devices incorporating these dendrimers as spin-coated emitting layers gave external quantum efficiencies of up to a 3.4 %, which suggests that this device is harvesting triplet excitons. This result indicates that carbazole dendrimers with attached acceptors are potential TADF materials owing to their polarized electronic structure (with HOMO–LUMO separation).

On the Equivalence of the Entropic Curvature-Dimension Condition and Bochner's Inequality on Metric Measure Spaces

Abstract: We prove the equivalence of the curvature-dimension bounds of Lott-Sturm-Villani (via entropy and optimal transport) and of Bakry--Emery (via energy and \Gamma_2$-calculus) in complete generality for infinitesimally Hilbertian metric measure spaces. In particular, we establish the full Bochner inequality on such metric measure spaces. Moreover, we deduce new contraction bounds for the heat flow on Riemannian manifolds and on mms in terms of the $L^2$-Wasserstein distance.

Attenuation of Conducted EMI Emissions From an Inverter-Driven Motor

Abstract: This paper provides theoretical and experimental discussions on conducted electromagnetic interference (EMI) emissions from an inverter-driven motor rated at 400 V and 15 kW. It focuses on a line EMI filter and its combination with a motor EMI filter, along with their effects on attenuation of conducted emission voltage. When no EMI filter is connected, the motor drive cannot meet the conducted emission limits prescribed by Category 3 in the IEC61800-3 regulations. The reason is that the common-mode voltage generated by a voltage-source pulse width modulation (PWM) inverter causes a common-mode leakage current flowing into the ground wire lead through parasitic capacitors inside the motor. When the line EMI filter is connected, the motor drive can meet Category 3. The motor EMI filter eliminates the common-mode voltage from the motor terminals, thus bringing a drastic reduction to the leakage current. The combination of the two EMI filters can comply with the limits prescribed by Category 2, which are much stricter than those by Category 3.

A Highly Efficient Mononuclear Iridium Complex Photocatalyst for CO2 Reduction under Visible Light

Abstract: Development of photocatalysts for the reduction of CO2 by sunlight is increasingly becoming an important research area owing to fossil-fuel shortage and global warming. Developing a photosynthetic system that generates solar fuel from CO2, H2O, and sunlight is a promising approach. Photocatalytic systems, including transition-metal complexes such as ruthenium(II) polypyridine carbonyl complexes, cobalt(II) trisbipyridine, and cobalt(II) macrocycles combined with a photosensitizer, can reduce CO2 with a relatively high quantum yield and high product selectivity. Among them, the rhenium(I) bipyridine (bpy) complex systems are the only mononuclear systems that exhibit definite photocatalytic activity for CO2 reduction. A typical example is fac-[Re(bpy)(CO)3Cl], developed by Lehn, which reduces CO2 to CO under UV irradiation without any additional photosensitizers. Cobalt porphyrins can also act as a CO2 reduction catalyst without a photosensitizer. [3c] A fac-[Re(bpy)(CO)3{P(OEt)3}] + complex is an efficient photocatalyst for CO2 reduction in a homogeneous system that selectively produces CO with a quantum yield of 0.38 at the ultraviolet light irradiation of 365 nm. However, the compound must be modified to allow effective use of solar energy because its absorption in the visible region is limited to wavelengths less than 440 nm. Thus, activation of highly active Re complex photocatalysts toward the visible region is necessary. Furthermore, the photocatalytic activity for CO2 reduction is very low in the presence of H2O, even at a concentration of 10 %. Therefore, for CO2 reduction, the development of metal complex photocatalysts that operate under visible light irradiation, even in the presence of H2O, is desirable. In Ir complexes, the stronger spin–orbit coupling coordinates with singlet and triplet excited states, leading to efficient luminescence and visible-light absorption from the singlet–triplet transition. Therefore, Ir complexes have been used as an emitter for electroluminescence devices, a photosensitizer for photocatalytic reactions, and a light-absorber for Gr tzel solar cells. Recently, it was reported that an Ir complex acted as a water oxidation catalyst with a sacrificial electron accepter and a CO2 reduction catalyst with an electronical bias or in the presence of hydrogen. Although Ir complexes are considered suitable for photocatalysis owing to visible-light absorption from S–T transitions and a longer lifetime of the excited state, no studies on Ir complex photocatalysts for CO2 reduction have been reported. This report describes the successful development of a novel photocatalyst, mononuclear iridium(III) terpyridine (tpy) 2-phenylpyridine (ppy) complex [Ir(tpy)(ppy)Cl] ([Irppy]), which selectively reduced CO2 to CO under visible light at 480 nm without additional photosensitizers such as in the case for Re complexes. Furthermore, advantages of the Ir complexes over Re complexes include: 1) greater photocatalytic activity for CO2 reduction; 2) CO2 reduction under visible light, such as at a wavelength of 480 nm; and 3) the photocatalytic activity is maintained (including selectivity) even in a solution containing H2O. [Ir-ppy] catalyzed the reduction of CO2 molecules to CO under visible-light irradiation. Figure 1 shows the photocatalytic formation of CO over [Ir-ppy] compared with conventional [Re(bpy)(CO)3Cl] under visible light irradiation