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The ternary zinc nitrides CaZn2N2 and SrZn2N2 are promising materials for solar energy conversion because their direct band gaps are tunable to optimal values, and they contain only earth-abundant ...

The root cap is a multi-layered tissue covering the tip of a plant root that directs root growth through its unique functions such as gravity-sensing and rhizosphere interaction. To prevent damages from the soil environment, cells in the root cap continuously turn over through balanced cell division and cell detachment at the inner and the outer cell layers, respectively. Upon displacement toward the outermost layer, columella cells at the central root cap domain functionally transition from gravity-sensing cells to secretory cells, but the mechanisms underlying this drastic cell fate transition are largely unknown. By using live-cell tracking microscopy, we here show that organelles in the outermost cell layer undergo dramatic rearrangements, and at least a part of this rearrangement depends on spatiotemporally regulated activation of autophagy. Notably, this root cap autophagy does not lead to immediate cell death, but rather is necessary for organized separation of living root cap cells, highlighting a previously undescribed role of developmentally regulated autophagy in plants.Summary statementTime-lapse microscope imaging revealed spatiotemporal dynamics of intracellular reorganization associated with functional transition and cell separation in the Arabidopsis root cap and the roles of autophagy in this process.

To improve the penumbra of low‐energy beams used in spot‐scanning proton therapy, various collimation systems have been proposed and used in clinics. In this paper, focused on patient‐specific brass collimators, the collimator‐scattered protons' physical and biological effects were investigated. The Geant4 Monte Carlo code was used to model the collimators mounted on the scanning nozzle of the Hokkaido University Hospital. A systematic survey was performed in water phantom with various‐sized rectangular targets; range (5–20 cm), spread‐out Bragg peak (SOBP) (5–10 cm), and field size (2 × 2–16 × 16 cm2). It revealed that both the range and SOBP dependences of the physical dose increase had similar trends to passive scattering methods, that is, it increased largely with the range and slightly with the SOBP. The physical impact was maximized at the surface (3%–22% for the tested geometries) and decreased with depth. In contrast, the field size (FS) dependence differed from that observed in passive scattering: the increase was high for both small and large FSs. This may be attributed to the different phase‐space shapes at the target boundary between the two dose delivery methods. Next, the biological impact was estimated based on the increase in dose‐averaged linear energy transfer (LET d) and relative biological effectiveness (RBE). The LET d of the collimator‐scattered protons were several keV/μm higher than that of unscattered ones; however, since this large increase was observed only at the positions receiving a small scattered dose, the overall LET d increase was negligible. As a consequence, the RBE increase did not exceed 0.05. Finally, the effects on patient geometries were estimated by testing two patient plans, and a negligible RBE increase (0.9% at most in the critical organs at surface) was observed in both cases. Therefore, the impact of collimator‐scattered protons is almost entirely attributed to the physical dose increase, while the RBE increase is negligible.

Niobium oxynitride (NbON) is a promising photoanode material for photoelectrochemical water splitting using visible light up to ∼600 nm in wavelength. However, the NH 3 nitridation method widely used for oxynitride synthesis cannot convert Nb2O5 (Nb5+) to crystalline NbON (Nb5+), due to the generation of NbOxNy (Nb2+−3+). To prevent Nb reduction during nitridation, we added O2 as an oxidant to the NH 3 nitridation reaction system. Investigation of the relationship between O2 concentration and the crystal phase of the resulting samples revealed that Nb2O5 nitridation produces crystalline NbON (Nb5+) within a specific O2 concentration range. The O2 concentration required to synthesize NbON increases from 0.05% to over 0.40% upon increasing the nitridation temperature from 600 °C to 750 °C. The photoelectrochemical properties of NbON films were also investigated. Under simulated sunlight illumination, a NbON photoanode produced a photocurrent of 0.6 mA cm-2 at 1.2 V vs. RHE in H2O2 aqueous solution.

Because inorganic solid electrolytes are one of the key components for application to all-solid-state batteries, high-ionic-conductivity materials must be developed. Therefore, we propose a method of efficiently evaluating the activation energy of ionic diffusion by calculating a potential-energy surface (PES), searching for the optimal diffusion path by an algorithm developed using dynamic programming (DP), and calculating the corresponding activation energy by the nudged elastic band (NEB) method. Taking beta-Li3PS4 as an example, the activation energy of Li-ion diffusion was calculated as 0.43, 0.25, and 0.40 eV in the a-, b-, and c-axis directions, respectively, which is in good agreement with previously reported values. By comprehensively searching for the lowest energy path by PES-DP, the arbitrariness of the path selection can be eliminated, and the activation energy must only be calculated using the NEB method a few times, which greatly reduces the computational cost required for evaluating activation energy and enables the high-throughput screening of solid state electrolytes., 8 pages, 10 figures

Efforts are being focused on increasing the power of extreme ultraviolet (EUV) light sources used in semiconductor manufacturing to increase the throughput. As a result, the investigation of the effect of high power sources on resist materials is a critical issue. A chemically amplified resist (CAR) and a non-CAR were irradiated with 13.5 nm EUV high-flux pulses from a soft X-ray free-electron laser (FEL). In the non-CAR, the positive-tone resist (ZEP520A) exhibited lower sensitivity at high irradiation densities, while the negative-tone resist exhibited a higher sensitivity. In addition, the dose rate did not considerably affect the sensitivity of the CAR.

The transient distribution of lightning current, which flows in a multilayer carbon-fiber-reinforced plastic (CFRP) material of aircraft, has been studied using the finite-difference time-domain (FDTD) method. Each layer of the multilayer CFRP panel has a fiber direction of 45°, 90°, −45° or 0°, and, therefore, has an anisotropic conductivity. It is quite difficult to represent such an anisotropic layered panel using the FDTD method with common rectangular prism or cubic cells. In this paper, the distribution of lightning currents on a 3-mm-thick multilayer CFRP panel, composed of 16 layers, is computed using the FDTD method with a conductivity matrix approach.

Vortex motions in a stably stratified rotating fluid are considered theoretically, based on the quasigeostrophic approximation. A class of exact solution is obtained, which represents a tilted spheroidal volume with uniform potential vorticity embedded in an otherwise quiescent fluid of infinite extent. The spheroid rotates steadily about the vertical axis, where the angular velocity is independent of the inclination angle of the axis of symmetry from the vertical axis. We study the stability of these solutions against infinitesimal disturbances. Highly elongated prolate spheroids are shown to be unstable if the inclination angle is large. In contrast, oblate spheroids of certain aspect ratio are unstable even if the inclination angle is very small. This instability is caused by resonace between the tilted rotation and other disturbance modes.

Electroluminescent porous Si (PS) diodes exhibit various useful functions under a high-electric field. The experimental PS diodes are composed of thin semitransparent metal films, PS layers (about 500 nm thick in minimum), p- or n-type Si substrates and ohmic back contacts. Definite nonlinear electrical behavior (negative resistance and nonvolatile bistable memory effects) and cold electron emission phenomena appear in these PS diodes associated with the EL emission. Both the negative resistance and memory effects are related to the charging of Si nanocrystallites by field-induced carrier injection. The electron emission observed in the PS diodes formed on n+–Si substrates is caused by hot electrons tunnelling through the top contact. By an appropriate structural control of PS, the effective drift length under a high-field conduction is significantly increased, and then electrons are emitted ballistically. These functions reflect the activity of PS as a nanocrystalline confined system.

It is demonstrated that there are distinct off and on states in the current–voltage characteristics of porous silicon (PS) diodes, and that the visible electroluminescence (EL) is observed in the on state. The PS diodes are composed of semitransparent thin Au films, rapid thermal oxidization (RTO)-treated PS layers (∼0.5 μm thick), p-type Si substrates, and ohmic back contacts. After the PS layers were prepared by anodizing Si wafers in an ethanoic HF solution, the samples were treated by RTO process. The bistable states of this PS diode can be simply and reversibly controlled by the external bias voltage. Based on the behavior of the EL and capacitance–voltage characteristics, the model of memory effect is presented, in which field-induced carrier injection and ejection into and from silicon nanocrystallites strongly affects the carrier transport.

Uremic pruritus is a very common and frustrating condition for both patients and clinicians because no treatment has been demonstrated to be effective in relieving the itch. In this report, nalfurafine, a new kappa-opioid receptor agonist, was used to treat uremic pruritus in patients who were undergoing routine hemodialysis. Two multicenter, randomized, double-blind, placebo-controlled studies enrolled 144 patients with uremic pruritus to postdialysis intravenous treatment with either nalfurafine or placebo for 2 to 4 wk. A meta-analysis approach was used to assess the efficacy of nalfurafine. Statistically significant reductions in worst itching (P = 0.0212), itching intensity (P = 0.0410), and sleep disturbances (P = 0.0003) were noted in the nalfurafine group as compared with placebo. Improvements in itching (P = 0.0025) and excoriations (P = 0.0060) were noted for the nalfurafine-treated patients. Nalfurafine showed similar types and incidences of drug-related adverse events as did placebo. Nalfurafine was shown to be an effective and safe compound for use in this severely ill patient population.

Some nonlinear electrical characteristics in electroluminescent porous silicon (PS) diodes with a relatively thin PS layer (0.5–5 μm thick) are described. The experimental PS diodes were composed of a semitransparent Au film, a PS layer, p- or n-type Si substrate, and an ohmic back contact. The PS layers were prepared by anodizing Si wafers in an ethanoic HF solution. In some cases, the PS layers were treated by rapid thermal oxidization (RTO) process. When the bias voltage is applied, the PS diodes show the electrical behavior like the metal-insulator-semiconductor (MIS) diodes. The negative-resistance characteristics and memory effect are also observed. These results indicate that the quantum-structured nature of the PS layer appears not only in the optical properties but also in the electrical properties.

Definite negative-resistance (NR) effects in electroluminescence(EL)-emissive porous silicon (PS) diodes have been investigated in relation to the EL characteristics. The PS diode is composed of a semitransparent thin Au film, a relatively thin PS layer, a n+- or p-type Si substrate and an ohmic back contact. When the forward bias voltage is applied to the diode, a reversible NR behavior is observed in the current–voltage (I–V) characteristics at room temperature. At a low temperature of 10 K, the peak-to-valley current ratio in the n+-type substrate case extends to about 104. It is shown that the EL emission is switched on at the onset of the NR effect. For the p-type substrate diode, the NR effects can be activated by photoillumination. The mechanism of the observed NR effects is also discussed from the viewpoint of electron injection into the silicon nanocrystallites in PS. The NR effects can be regarded as one of the field-induced functions of PS as a quantum-sized crystalline system.

We report the optical and electrical properties of deuterium terminated porous Si. It is found that the replacement of hydrogen with deuterium reduces the degradation not only of photoluminescence but also of electroluminescence. The luminescence degradation was analyzed using a rate equation model for photoinduced oxidation.