Reversible and Precisely Controllable p/n‐Type Doping of MoTe2 Transistors through Electrothermal Doping

Precisely controllable and reversible p/n‐type electronic doping of molybdenum ditelluride (MoTe₂) transistors is achieved by electrothermal doping (E‐doping) processes. E‐doping includes electrothermal annealing induced by an electric field in a vacuum chamber, which results in electron (n‐type) doping and exposure to air, which induces hole (p‐type) doping. The doping arises from the interaction between oxygen molecules or water vapor and defects of tellurium at the MoTe₂ surface, and allows the accurate manipulation of p/n‐type electrical doping of MoTe₂ transistors. Because no dopant or special gas is used in the E‐doping processes of MoTe₂, E‐doping is a simple and efficient method. Moreover, through exact manipulation of p/n‐type doping of MoTe₂ transistors, quasi‐complementary metal oxide semiconductor adaptive logic circuits, such as an inverter, not or gate, and not and gate, are successfully fabricated. The simple method, E‐doping, adopted in obtaining p/n‐type doping of MoTe₂ transistors undoubtedly has provided an approach to create the electronic devices with desired performance.     

The study on change of mechanical properties of NBR due to deterioration

Rubber is an important industrial material. However, mechanical properties and deformation of the high polymer including rubber are not clear. A method of estimating the mechanical properties which can be used for the deteriorated rubber is demanded to improve the reliability of it. Improved VBO (Viscoplasticity theory based on overstress) model is a constitutive equation. We applied it for the compression stress-strain behavior of deteriorated NBR (acryloNitrile-Butadiene rubber). Furthermore, we proposed a method of estimating the mechanical properties of deteriorated NBR. In this paper, deterioration tests in water and in air were conducted. To confirm the validity of the proposed improved VBO model and estimated mechanical properties, simulations of the stress-strain curves obtained in the tests were conducted.     

On-line measurement of orientation development in the high-speed melt spinning process

On-line measurement of birefringence was performed in the high-speed melt spinning process of poly(ethylene terephthalate) using an apparatus that incorporates a rotating polarizer for the measurement of the optical retardation of running filament. Particular attention was paid to the detailed measurements in the vicinity of neck-like deformation. Through the measurement at the take-up velocity of 5 km/min, development of birefringence under the strain rate up to about 1 ms^?1 was investigated. To analyze the relation between applied stress and birefringence, tension and temperature profiles of the spin-line were calculated based on the experimentally obtained diameter profiles. Even though the strain rate is extremely high, a linear relationship between birefringence and a parameter calculated by dividing stress by temperature was confirmed to hold up to birefringence and stress/temperature values of about 0.017 and 10 kPa/K, respectively.     

Energy storage system utilizing large‐capacity electric double‐layer capacitors for peak‐cut of power demand

Recently, due to a rapid increase of demand for air conditioning in summer, peak power demand is becoming increasingly acute. Therefore, the load factor has a tendency to drop every year. The drop of the load factor is leading to a drop in the utilization factor of the power facilities and an increase in the cost of installation. In this paper, we propose an energy storage system for peak‐cut of power demand, in which we use large‐capacity electric double‐layer capacitors. This energy storage system has some distinctive characteristics, including long life span, maintenance‐free operation, preservation of environment, high efficiency at charge/discharge, and so on. This paper deals with the circuit arrangement of the proposed energy storage system, the charge equalization method of the capacitors, and the control method of the converter at charge/discharge. Finally, the operating characteristics of this system are evaluated by simulation analysis. © 2000 Scripta Technica, Electr Eng Jpn, 133(3): 83‐92, 2000     

Improvement of inductive power collection in null-flux maglev system

In the superconducting maglev system it is important to develop a non-contact on-board power source without environmental pollution such as noise and exhaust gases; therefore, inductive power collection (IPC), which utilizes a harmonic magnetic field generated by ground coils in EDS, is being studied. However, alteration to a null-flux EDS that has a high drag ratio reduces the power collecting capacity in the IPC system. In addition, power collecting coils are located on the cryostat of the superconducting coil (SC), so eddy currents at the cryostat also reduce the power collecting capacity. Therefore, an exclusive SC type that locates the exclusive SCs and IPC and power collecting coils so as to face the upper and lower coils of ground coils, respectively, is examined; but we aim to improve the conventional type. After analyzing the influence of eddy currents at the cryostat in detail and improving the composition of the power collecting coil and cryostat, we found that the conventional type has the same capacity as the exclusive SC type. In order to prove the above-mentioned result, we measured the induced voltage of the new-type coils in a test run at Miyazaki test track and confirmed the output of this IPC system in a full-scale synthetic bench test with a PWM converter and magnetic field simulator. © 1998 Scripta Technica. Electr Eng Jpn, 122(2): 48–60, 1998     

Fault current limiting system for 500‐kV power systems

Recently, expansion in the scale of power systems and development of localized power sources are leading to an increase in fault current of 500‐kV systems. In the future, it is quite likely that the fault current at the interconnection of such power systems may exceed the rated short‐time current of existing electric power facilities. As one of the solutions of this problem, a thyristor‐controlled series‐resonant‐type fault current limiter (FCL) is proposed to restrain the fault current. This paper deals with the FCL system configuration, the placement method of the FCL in power systems, the outline of the FCL's specification, and the operation method of the protective relay in the multimachine system. Finally, the effectiveness of the FCL is evaluated from the viewpoints of limiting the fault current by simulation analysis. The FCL is shown to be a useful protection device for large, high‐capacity power systems. © 1999 Scripta Technica, Electr Eng Jpn, 127(1): 11–22, 1999     

Enhancement of recombinant soluble dengue virus 2 envelope domain III protein production in Escherichia coli trxB and gor double mutant

The dengue virus is currently the most important flavivirus causing human diseases in the tropical and subtropical regions of the world. The envelope protein domain III of dengue virus type 2 (D2EIII), which induces protective and neutralizing antibodies, was expressed as an N-terminal fusion to a hexa-histidine tag in Escherichia coli. The expression of recombinant D2EIII of 103 amino acids in the soluble form can be achieved using suitable host strains, such as Origami, at a low induction temperature of 18 degrees C. The enhanced production of the soluble protein could be attributed to the thioredoxin reductase (trxB) and glutathione reductase (gor) double mutations in the Origami genome. The soluble and refolded D2EIII proteins were recognized by different antibodies including human patient antiserum. The immunization of rats with soluble D2EIII protein elicited the production of antibodies that could recognize the D2EIII protein in the D2EIII precursor protein and in C-terminal truncated dengue envelope protein type 1-4. Thus, this protein production system is suitable for the production of authentic recombinant dengue proteins that may be used in the diagnosis of the dengue virus infection or in vaccine development.     

Comparative study of behavior of inhaled samarium and cerium in mice

Distribution of Sm and Ce in mice was investigated after inhalation exposure to their oxide particles of 5 μm diameter and 15 mg/m3.Sm and Ce were mainly distributed in lung,their concentrations decreased with passing time,and their concentrations in lung were correlated with exposure periods.Concentrations of Ce were lower than that of Sm in each point.Sm was also distributed in the other organs and bone but Ce was scarcely detected.These results suggest that the behaviors of Sm and Ce inhaled were different,although their chemical properties are similar.