356 research outputs found

    Unveiling hidden topological phases of a one-dimensional Hadamard quantum walk

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    Quantum walks, whose dynamics is prescribed by alternating unitary coin and shift operators, possess topological phases akin to those of Floquet topological insulators, driven by a time-periodic field. While there is ample theoretical work on topological phases of quantum walks where the coin operators are spin rotations, in experiments a different coin, the Hadamard operator is often used instead. This was the case in a recent photonic quantum walk experiment, where protected edge states were observed between two bulks whose topological invariants, as calculated by the standard theory, were the same. This hints at a hidden topological invariant in the Hadamard quantum walk. We establish a relation between the Hadamard and the spin rotation operator, which allows us to apply the recently developed theory of topological phases of quantum walks to the one-dimensional Hadamard quantum walk. The topological invariants we derive account for the edge state observed in the experiment, we thus reveal the hidden topological invariant of the one-dimensional Hadamard quantum walk.Comment: 11 pages, 4 figure

    Improved controllability of wet infiltration technique for fabrication of solid oxide fuel cell anodes

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    Ni/yttria-stabilized zirconia anodes of solid oxide fuel cells are fabricated by a wet infiltration technique and the ability of the infiltration technique to control the anode microstructure is quantitatively demonstrated by a detailed three-dimensional microstructural analysis. The microstructural analysis reveals favorable aspects of the infiltrated anodes, such as larger triple-phase boundary density and sufficiently large pore size, and they are mostly unachievable by the conventional powder-mixing and sintering approaches. The improved controllability of the infiltration technique is expected to be useful to tailor porous microstructures to meet the multiple requirements for transport and electrochemical reactions within the anodes

    REMOTE BACTERICIDAL ACTIVITY OF TIO2 NANOPARTICLES

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    The remote bactericidal effect of TiO2 photocatalyst, i.e., the bactericidal effect away from the photocatalyst, was successfully achieved using a humidified airflow. The TiO2 photocatalyst used was anatase-type TiO2 nanoparticles (NPs) annealed with a low-temperature O2 plasma. For comparison, anatase-type TiO2 NPs annealed in the air were used. The bacteria, Bacillus subtilis, were placed away from the TiO2 NPs. The plasma-assisted-annealed TiO2 NPs significantly inactivated 99% of the bacterial cells in 5 h, whereas the pristine and air-annealed TiO2 NPs inactivated 88-90% of the bacterial cells. The remote bactericidal effect of plasma-assisted-annealed TiO2 NPs would be attributed to a larger amount of H2O2 molecules traveled by the airflow from the TiO2 NPs. The molecules were generated by chemically reacting more photoexcited carriers on the TiO2 surface with H2O and O2 in the airflow. These photoexcited carriers originated from more oxygen-based species adsorbed and more oxygen vacancies introduced on the TiO2 surface by the plasma-assisted-annealing

    Steady‐State and Time‐Resolved Optical Properties of Multilayer Film of Titanium Dioxide Sandwiched by Gold Nanoparticles and Gold Thin Film

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    We proposed metal-insulator (MI) and metal-insulator-metal (MIM) structures of titanium dioxide (TiO2) sandwiched by gold nanoparticles (AuNPs) layer and gold sputtered thin film (only for the MIM film) to couple localized plasmon mode of AuNP with multi-reflection mode and/or cavity resonator mode of TiO2. The optical extinctions of MI and MIM with differing TiO2 thickness were studied theoretically by finite-element method simulation and experimentally by optical spectrometry. The extinction peaks of MI and MIM shifted by exchanging the surrounding medium from air to TiO2. The interference of TiO2 in MI structure also affected the extinction spectra showing the oscillation along the spectrum of AuNP in TiO2. Then, the extinction degree of MIM was higher than that of MI because of the coupling between cavity resonance mode with localized plasmon mode and interband transition in AuNPs. In addition, the cross section of MI and MIM films were observed by scanning electron microscopy. The surface of thinner film was rough because TiO2 heterogeneously grew from AuNP. The irregular growth of TiO2 might have induced the wide-range extinction in 300-2500 nm after Au thin film deposition. The transient absorption spectra using a femtosecond laser were also carried out under the condition of 800 nm for excitation laser and 950 nm for probe laser. The long-lived electron (~1 ns) was observed in thick MIM film as a result of hot electron transfer from the gold nanostructure in the film

    Implantable pneumatically actuated microsystem for renal pressure-mediated transfection in mice.

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    In vivo transfection is an important technique used in biological research and drug therapy development. Previously, we developed a renal pressure-mediated transfection method performed by pressing a kidney after an intravenous injection of naked nucleic acids. Although this is a useful method because of its safety and wide range of applications, an innovative approach for performing this method without repeatedly cutting open the abdomen is required. In this study, we developed an implantable microsystem fabricated by Micro-Electro-Mechanical Systems (MEMS) technologies for renal pressure-mediated transfection. The system consists of a polydimethylsiloxane pneumatic balloon actuator (PBA) used as an actuator to press the target kidney. The PBA of the implanted microsystem can be actuated without opening the abdomen by applying air pressure from outside the body to the pressure-supplying port via a needle. We successfully performed renal pressure-mediated transfection using the newly developed system when the implanted system was activated at 60kPa for 10s. This is the first report of an implantable MEMS-based microsystem that demonstrates in vivo transfection to a kidney using naked plasmid DNA

    長期ホルマリン固定により失活したProliferating Cell Nuclear Antigen (PCNA) の免疫反応性回復条件の基礎的検討 ―マイクロウェーブ、オートクレーブの影響について―

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    Using paraffin-embedded tissue sections of liver cancer obtained from autopsy which had been preserved in 10% buffered formalin solution for 6 months while PCNA immunoreactivity was lost, we examined the effects of heat processing by either microwave(MW) and autoclave(AC) in the presence of various processing solution. It appeared that AC processing took shorter time period than MW irradiation to restore equal immunoreactivity. With regard to immunoreactivity retrieval by MW irradiation,however, variation of the degree of retrieval depending on processing time was smaller than in AC, and so the stable consequences were obtained. Although AC processed tissues tended to be stained deep, prolonged processing time presented strong background staining and blurred nuclear margins which made it difficult to estimate the positive cell count. As for the effects of processing solution, there was little difference in retrieval of PCNA among 0.01 M citrate buffer (pH 6.0), saturated solution of lead thiocyanate and distilled water, but the least background staining was observed with distilled water. These observations suggest that MW irradiation of which effect of retrieval is less dependent of processing time and with the least background stainability, is superior to AC processing for PCNA immunoreactivity retrieval on formalin-fixed tissues.10%緩衝ホルマリンに6ヶ月間浸漬していた剖検材料(肝臓癌)のパラフィン包埋後の組織切片を用いて、ホルマリンの固定作用により失活したPCNAの免疫反応性の回復にマイクロウェーブ(MW)及びオートクレーブ(AC)による熱処理とその時用いる処理溶液が、どのような影響を与えるかについて検討した。その結果、同等の免疫反応性を回復するのには、AC処理の方がMW照射より短時間でよいことが解った。しかし、MW照射による免疫反応性回復では、処理時間による影響がAC処理に比べて少なく、安定した結果が得られた。また、PCNAの染色所見については、AC処理の方が濃く染まる傾向が見られた。しかし、処理時間が長くなるとバックグラウンドの染色性が高くなる、核の周囲ににじみ現象が見られる等の所見があり判定に困難をきたした。一方、処理溶液についてはクエン酸(0.01M pH6.0)、チオシアン酸鉛飽和溶液、蒸留水について検討を行った結果、PCNAの回復には差は認められなかったが、バックグラウンドの染色については蒸留水が最も少なかった。以上の結果により、ホルマリン固定により失活したPCNAの免疫反応性を回復するには、MW照射の方がAC処理より処理時間に関係なく安定した染色性が得られ、なおかつバックグラウンドの染色性が少ない等の点で優れていることが示唆された

    Ultra‐Narrowband Blue Multi‐Resonance Thermally Activated Delayed Fluorescence Materials

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    Ultra-narrowband blue multi-resonance-induced thermally activated delayed fluorescence (MR-TADF) materials (V-DABNA and V-DABNA-F), consisting of three DABNA subunits possessing phenyl or 2, 6-difluorophenyl substituents on the peripheral nitrogen atoms are synthesized by one-shot triple borylation. Benefiting from the inductive effect of fluorine atoms, the emission maximum of V-DABNA-F (464 nm) is blueshifted from that of the parent V-DABNA (481 nm), while maintaining a small full width at half maximum (FWHM, 16 nm) and a high rate constant for reverse intersystem crossing (6.5 × 10⁵ s⁻¹). The organic light-emitting diodes (OLEDs) using V-DABNA and V-DABNA-F as emitters are fabricated by vapor deposition and exhibit blue emission at 483 and 468 nm with small FWHMs of 17 and 15 nm, corresponding to Commission Internationale d’Éclairage coordinates of (0.09, 0.27) and (0.12, 0.10), respectively. Both devices achieve high external quantum efficiencies of 26.2% and 26.6% at the maximum with minimum efficiency roll-offs of 0.9% and 3.2%, respectively, even at 1000 cd m⁻², which are record-setting values for blue MR-TADF OLEDs
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