In this work, the characteristics of a diode with a p-n junction located in a magnetic field were investigated. Current-voltage characteristics were observed in the presence and absence of a magnetic field at different temperatures and the results were compared with experimental results. In addition, the dependence of the voltage on temperature in various magnetic fields was observed and graphs were obtained. The voltage decreases as the temperature increases, and this result is consistent with the experimental ones. The necessary conclusion was drawn from the agreement of the theoretical results with the experimental results.

We have recently proposed a theoretical model for the mechanism of heat production in the mitochondrial respiratory chain, derived from the overpotential of electrochemical reactions in enzyme catalysis. A key feature of this overpotential-derived thermogenesis model is that the distribution of energy consumption between thermogenesis and adenosine triphosphate synthesis changes depending on the reaction rate. To verify that similar energy partitioning occurs in other metabolic reactions linked to the respiratory chain, we developed a system for the simultaneous measurement of thermogenesis and respiration rate in yeast cells. We correlated the amount of thermogenesis with the respiration rate, finding that most thermogenesis in yeast cells is derived from fermentation, which is connected to the respiration rate. By investigating the relationship between fermentative heat production and respiration rate, we discovered that the energy partitioning between heat production and substance synthesis exists and changes depending on the respiration rate. This strongly suggests the existence of electrochemical overpotential-derived thermogenesis in metabolic processes.

When a voltage applied between a pair of metal electrodes is increased in gas atmosphere, gas discharge breakdown occurs at a certain voltage (a breakdown voltage). This voltage depends on gas species. In other words, gas sensing possible by measuring their breakdown voltages. However, voltage for gas discharge breakdown using conventional metal electrode is generally high under atmospheric pressure. Thus, reduction of the discharge voltage is desirable for the application mentioned above. This study aims at considering possibility to develop gas sensing method by detecting gas discharge breakdown occurring at a relatively low voltage. Electrodes on which carbon nanotubes (CNTs) were attached were used for this purpose. CNTs possess fibrous shapes with nano-sized tip radii. This shape generates very high electric field on the tip. The high field enables reduction of the breakdown voltage. Our results showed that the electrode with CNTs gave dependence of gas discharge breakdown voltages on gas species with relatively lower applied voltages. The breakdown voltage linearly changed with respect to composition ratios of gas mixtures. It is considered that these characteristics originate in field emission electrons from the CNTs.

In this study, we evaluated the refractive indices of silicon dioxide (SiO₂) optical thin films deposited using a combinatorial coating method comprising electron beam (EB) evaporation and direct-current pulse sputtering. The combinatorial deposition system can fabricate optical thin films by simultaneously operating EB evaporation and sputtering within the same vacuum chamber. The refractive indices of the deposited films can be reduced by increasing the degree of vacuum during deposition and decreasing the deposition rate ratio of sputtering, substrate temperature, and sputtering output owing to a decrease in the film packing density due to the reduced mean free path of deposited particles and surface diffusion. When the sputter output and deposition rate ratio of sputtering were low, cracks were observed during simultaneous deposition, indicating that sputtered particles can suppress cracks in the film. Simultaneous deposition can be used to fabricate SiO₂ optical thin films with a refractive index of 1.17. The films were crack-free and exhibited a low light scattering intensity ratio of less than 0.1%. Further, they were not peeled off upon crosshatch testing or ultrasonic cleaning and had sufficient adhesion for practical use.

The work presented here aims to optimize parameters for emission current and lifetime based on thermionic, microstructural and chemical characterization. Carburization was performed using toluene in a test structure consisting of a straight 0.006-inch diameter 2% thoria-tungsten wire, tensioned with a leaf spring and concentric to the inner diameter of a 1-inch long, 0.250-inch diameter molybdenum tube serving as the anode for emission testing. Scanning electron microscope/energy dispersive spectroscopy analysis shows the formation of a ∼5 µm carburization layer, while thermionic measurements show improved emission over uncarburized thoriated tungsten.

Two factors have hindered the extraction of surface structural information by repulsive desorption of hyperthermal products. The first is associated with non-angle resolved (AR) desorption analyses, especially non-AR-resonance-enhanced multiphoton ionization combined with time-of-flight. This ignores the anisotropy of desorption that conveys structural information and overlooks the coupling of rotational and translational modes in repulsive desorption, leading to an overestimation of the translational energy of high rotational energy states. Second, the detailed balance principle has been incorrectly used in desorption dynamics, leading to a mixing of adsorption and desorption dynamics and obscuring the energy transfer to each mode of desorbed products. Based on these considerations, a new partitioning of energy is proposed for the associative D₂ desorption on Cu(111).

A pyroelectric crystal has spontaneous polarization and generates a high voltage of several tens of kilovolts between both ends of the crystal with a temperature change of several tens of degrees Celsius. When this pyroelectric crystal is set in a vacuum with a counter electrode, electrons can be accelerated by this high voltage. Such a device can be used as an X-ray source without any external high-voltage sources. In this study, a thin copper foil was set at the end of a vacuum chamber as a target electrode and partitioned between the vacuum and atmosphere. The pyroelectric crystal was heated using infrared (IR) laser light. The X-ray was detected outside the vacuum chamber. The X-ray yield and the maximum energy during the laser irradiation cycle were higher than those during the natural cooling cycle. A transmission X-ray image of the lead foil sandwiched between aluminum foils was observed outside the vacuum chamber. In addition, a fingertip-sized miniature X-ray source using the IR laser light through an optical fiber was used to heat the pyroelectric crystal. The sizes of the fingertip-sized miniature X-ray source were 10 mm in outer diameter and 10 mm in length. The X-ray yield and the maximum energy during the laser irradiation cycle were less than those during the natural cooling cycle, which differed from the experimental results obtained using the vacuum chamber. This was due to fewer electrons in the fingertip-sized miniature X-ray source and insufficient recovery of the compensating charge on the crystal surface during the natural cooling cycle.

X-ray reflectivity (XRR) was applied to in-situ measurements of the interface of liquid electrolytes and electrodes of rechargeable batteries. Here, we report the in-situ XRR measurements during the charge and discharge of the zinc-anode battery. The combination of physical and chemical polishing of the Zn plate gave a flat surface, enough to produce the total reflection. Changes in the reflectivity curves during discharge and charge indicated that the Zn density decreased during discharge and increased during charge. This suggests that the uneven structure grew by Zn dissolution and decreased by Zn precipitation. This uneven surface becomes the starting point for dendrite growth. Using this method will make it possible to evaluate what kind of electrolyte to use for a more uniform reaction, which is expected to lead to the development of batteries with good cycle characteristics.

This paper suggests a novel method for the dynamic measurement and control of single-crystal tungsten micro-tip corrosion in order to address the problems of poor repeatability, low control precision, and the inability to set control tip diameters in the conventional single-crystal tungsten micro-tip electrochemical corrosion process. This technique begins by capturing experimental images using a video microscope, performing edge detection and contour searching to extract boundary information of the single-crystal tungsten micro-tip, and subsequently calculating and displaying the instantaneous tip diameter. Subsequently, a target diameter for the micro-tip is set, and when the detected value reaches this target, the software automatically cuts off the corrosion current. Experimental results demonstrate that this technique enables the production of high-quality single-crystal tungsten micro-tips with a diameter of approximately ⌀800 nm and exhibits excellent repeatability.

The utilization of superconductors as emitter material for field-emission cathodes has been investigated for the fundamental physics and practical applications of monochromatic electron emitters. The theoretical prediction of a narrow energy distribution and the empirical observation of a specific total energy distribution (TED) are the primary motivations of this study. We examined the TED of field-emitted electrons from a Bi₂Sr₂CaCu₂O_y (Bi-2212) cathode under different temperatures and applied voltages. The observed energy distribution appeared below the Fermi level of a typical metal, and symmetrical energy distribution was observed on both the high- and low-energy sides. The peak shifted toward the low-energy side and was separated into two peaks as the applied voltage increased, a phenomenon distinctly noticeable at low temperatures. These findings are attributed to field emission that originated from the atomic site on the edge of Bi-2212, where the shift in energy level within the atoms is due to the external field.

Pyrocatechol is a toxic substance which easily pollutes the environment and Nd vanadate nanowires (NdVONs) were developed for the electrochemical detection of pyrocatechol in the water environment. NdVONs were controllably synthesized via a facile hydrothermal approach using Nd trifluoromethanesulfonate and sodium vanadate. The formation mechanism of the NdVONs was investigated by controlling the synthesis parameters. The obtained nanowires possess single crystalline tetragonal NdVO₄ structure with a length of <10 µm and a diameter of 30–100 nm. There is a well-defined anodic peak at +0.12 V at the NdVON-modified electrode in 0.1 M phosphate buffer saline (PBS) electrolyte containing 1 mM pyrocatechol. The optimized measurement parameters for pyrocatechol detection including a pH value of PBS solution, a deposition time, a deposition potential, and a standing time are pH = 8, 60 s, +1.5 V, and 60 s, respectively. The NdVON-modified electrode indicates broad linear detection range of 0.01–1000 µM, a low limit of detection of 1.15 nM, a reliable stability, reproducibility, selectivity, and a practical application for pyrocatechol detection. The NdVONs are promising for pyrocatechol sensors.

In recent years, vacuum has attracted attention as an excellent insulating medium and is used in many high voltage and high electric field equipment. To improve the performance and reliability of the equipment, it is essential to improve the electric strength, and more advanced insulation technology is required. In a previous study, it was reported that apertures and the number of apertures affected the property of electron emission on electrodes with millimeter-sized apertures. Besides, micro-sized pits have been observed on electrode surface after chemical polishing and electric breakdown. However, it is not clear that how these micro-sized pits affect electron emission, whether they cause vacuum breakdown, or not. Therefore, the purpose of this study was to investigate the effect of micro-sized pits on electron emission. In this study, voltage-current measurement, and breakdown tests were conducted in vacuum using electrodes with and without micro-sized pits (5 µm square side). In addition, electric field simulations of electrodes with micro- or millimeter-sized pit were performed. From these results, it is considered that micro-sized pits have little effect on field electron emission and it is suggested that the micro-sized pits appeared after breakdown are probably generated by other physical processes following the breakdown.

Electron linacs based on superconducting radio frequency (SRF) technology are gaining attention as a highly efficient and high-power electron beam (EB) source for variety of applications. We also intend to apply the SRF technology for wastewater purification and radioactive isotope production that requires high-power EBs. Development of an electron source with high average current suitable for the SRF electron linac has been started. The objective of this work is to generate a pulsed EB with a high repetition rate, same as either the SRF accelerating frequency (1.3 GHz) or its subharmonic frequency. As even a small beam loss can quench SRF cavities, the EB produced by an electron gun should be of small emittance and sufficiently short pulses. Using simulation codes, the current dependence of the beam properties has numerically investigated based on the electron gun configuration at Research Center for Electron Photon Science (ELPH). At present, we are conducting studies to optimize and improve the electron gun including the grid pulser with design and development of the SRF linac. In addition, an electron gun test stand is currently under construction to experimentally evaluate the EB produced by the electron gun system. In this paper, we will present the results of numerical studies for the electron gun system.

Reducing the surface optical loss and broadening the spectral response range is an effective method to improve the power conversion efficiency of the multi-junction solar cells. We simulated the different HLHL (high/low/high/low index) antireflection coatings (ARCs) for the triple-junction solar cells based on an optical transfer matrix. From the ARC optimization results, the total effective reflectivity (R_e) of ZnS/MgF₂/ZnS/MgF₂ is the lowest among HLHL ARCs, which is 1.34%, best R_e at the region of interest appeared to be 5.03% for the top solar cell, 1.20% for the middle solar cell, and 0.93% for the bottom solar cell. Moreover, the effects of thickness, refractive index, and incident angle on the performance of the ZnS/MgF₂/ZnS/MgF₂ ARC were analyzed. It was found that the thickness of each film decreases when it deviates from the optimal theoretical value, and the appropriate reduction of MgF₂ refractive index can reduce total R_e. The ZnS/MgF₂/ZnS/MgF₂ ARC exhibits remarkable antireflection properties over a broad wavelength and a wide angular range. The experimental results showed that the reflectance spectrum of ZnS/MgF₂/ZnS/MgF₂ is basically consistent with the theoretical curve.

This paper presents the results of experimental studies of the structural characteristics of the epitaxial layers of GaAs_1−x−yZnSe_xGe_y solid solutions grown from a bismuth solution-melt on GaAs substrates with (100) crystallographic orientation. The grown epitaxial film of the GaAs_1−x−yZnSe_xGe_y solid solution is a single crystal with a sphalerite-like structure with the (100) orientation corresponding to the substrate orientation. It is shown that ZnSe molecules partially replace GaAs molecules in defect-capable regions of the (100) matrix crystal lattice at the high-potential sites.

Mode transitions in reactive sputtering of metal (Ti, V) oxides are studied. Under a controlled Ar gas pressure at a flow rate of 10 sccm, direct current sputtering plasma was generated. The oxygen flow rate Q and discharge power P were changed in two ways (Q was varied at fixed P, and vice versa), and the mode transitions were monitored using the state jump in the discharge voltage. When the transition points (P, Q) were plotted as two-dimensional (2D) maps, the metal-to-oxide and oxide-to-metal transition points were found to be located on two corresponding straight lines that passed through the origin, irrespective of how the parameters were varied. The origin of this behavior is discussed and ascribed to the linear relationship between the input power and the sputter etching rate of the target. These results also suggest that the metal-mode, hysteresis, and oxide-mode regions of the 2D map can be determined by a few pilot experiments. By depositing vanadium oxide films under conditions in the oxide-mode region, near its boundary, films with very similar optical properties could be obtained.