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MOS capacitors fabricated on substrates with doping concentrations as high as 1018 cm−3 were characterized at 4.2 K. The highly doped substrate exhibited an intrinsic imaginary component of impedance at 4.2 K. The imaginary component is attributed to the time delay induced by hopping phenomena, leading to a decrease in the gate capacitance. Furthermore, we investigated the time constant associated with dopant ionization under depletion conditions and determined it to be 0.35 μ s. An equivalent circuit model of the highly doped substrate at 4.2 K is also shown. [ABSTRACT FROM AUTHOR]

The donor properties at the interface of the PtO x /ZnO Schottky diodes on hydrothermally grown ZnO were investigated. From the capacitance–voltage (C–V) characteristics of the diode and Hall effect measurements of the bulk substrate, we revealed that the carrier concentration at the ZnO Schottky diodes interface is much higher than that in the bulk. By utilizing the C–V characteristics and the deep level transient spectroscopy, we demonstrated that the interfaces have two kinds of ionized donors; the shallow and deep donors, whose activation energies were 4 meV and 0.33 eV, respectively. Both of the two types of donors were ionized near the interface, whereas only the low-concentration shallow donors were ionized in the bulk. The shallow and deep donors were assigned to hydrogen interstadials and E3 defects, respectively. Since both the donor types are related to hydrogens, annealing in the oxygen atmosphere was effective to greatly suppress the donor concentration at the diode interface. [ABSTRACT FROM AUTHOR]

A nonvolatile resistive switching of NanoBridgeTM (NB) at 4 K has been demonstrated for realizing the Quantum-classical interface (QCI), in which the challenging of reset operation at cryogenic temperature is successfully achieved. The set voltage of the NB is increased with decreasing temperature, saturated around 150 K and to be 2.55 V at 4 K. The on-state resistances tuned at 1 k–5 kΩ show small temperature dependence down to 4 K due to high residual resistivity. The increased reset current of the NB at 4 K is compensated by the process optimization with thermal engineering and the increased I dsat of the select transistor at 4 K, resulting in stable switching. The low-power QCI featuring NBs is a strong candidate for controlling a large number of qubits at cryogenic temperature. [ABSTRACT FROM AUTHOR]

The understanding of carrier transport in metal nanostructures is indispensable for the development of nanoelectronics. In particular, Pt nanostructures have been intensively studied to realize gas sensors based on adsorbate-induced surface electron scattering. Conventionally, electron scattering at the surface of metal nanostructures has been phenomenologically described by a single specularity parameter. In this work, surface electron scattering was quantitatively studied through molecular dynamics simulations, followed by density functional nonequilibrium Green’s function calculations. Although the extracted specularity parameters qualitatively agreed with empirically treated diffusive scattering at the O-covered Pt surface and specular scattering at the H-covered Pt surface, our atomistic calculation revealed an increase in resistivity owing to H adsorption on thin Pt(111) nanosheets. [ABSTRACT FROM AUTHOR]

By utilizing stable thiol self-assembled monolayers (SAMs) on gold (Au) nanosheets, we investigated the temperature dependence of the amount of resistivity increases by SAM modification. increased with increasing temperature from 5 to 375 K in all the measured nanosheets for various thicknesses (9–20 nm). We consider from the DFT calculation that the temperature dependence originates from unoccupied states of sulfur atoms above the Fermi level of Au. The available unoccupied states increase at higher temperatures, which enhances scattering rates and thus increases the resistivity. Furthermore, we calculated the temperature dependence of using the Bloch–Grüneisen theory and Fuchs–Sondheimer (FS) model. Based on the results, we conclude that for ultra-thin metal films, the temperature-dependent specularity parameter which represents the fraction of electrons scattered specularly should be introduced into the conventional FS model to predict over a wide temperature range. [ABSTRACT FROM AUTHOR]

In situ ambient-pressure X-ray photoelectron spectroscopy (AP-XPS) combined with resistivity measurement was performed for a Pt thin-film H2 gas sensor. We experimentally demonstrate that the chemical state of the Pt surface changes under working conditions, and it directly links to the sensing performance. Moreover, the operating principle is discussed at the atomic scale. [ABSTRACT FROM AUTHOR]

For highly sensitive and selective sensors, numerical study of transistors functionalized with a defected self-assembled monolayer (SAM) was performed. Adsorption of water molecules on the defected SAM was treated by molecular dynamics (MD) calculations. Based on time dependent atomic positions and charges derived from the MD calculations, carrier concentration and threshold voltage of defected-SAM-functionalized transistors were derived from the Poisson equation. The defects of the SAM caused a penetration of water molecules. Due to a strong polarization of water molecules, the water molecules penetrating the defects were stacked in the same direction. The alignment of the water molecules in the defects generated a large electrical dipole, and the threshold voltage of the transistors were shifted. [ABSTRACT FROM AUTHOR]

Ferroelectric gating of functional materials has often suffered because ferroelectric materials are poor insulators. In this study, the recently reported ferroelectric HfO2, a large band‐gap oxide with excellent insulating properties, is exploited for electrostatically gating the archetypical metal–insulator transition material, VO2. By protecting the meta‐stable ferroelectric phase from deterioration, the ferroelectric gating is successfully demonstrated with an ultra‐thin VO2 channel in the back‐gate geometry. The observed modulation of the VO2 channel conductivity is originated from the ferroelectric polarization reversal in the HfO2 gate insulator combined with the VO2 metal–insulator transition. These results demonstrate the significant potential of ferroelectric HfO2 for electrostatically controlling the state of matter for both fundamental research and device application. [ABSTRACT FROM AUTHOR]

H2 and NH3 detection with low power consumption was demonstrated by integrated chemiresistive Pt and PtRh nanosheet sensors on glass substrates. The self-heating effects realized low power and local heating of metal nanosheet sensors, enabling the integration of sensors with different operating temperatures. Based on different resistance changes in Pt and PtRh nanosheets toward H2 and NH3, the concentration of each gas was detected from a gas mixture by consuming around 1-mW power. For decreasing the power consumption and further integration of sensors, sensor scaling and pulsed operations were numerically and experimentally studied. In addition to good connectivity of metal nanosheet sensors to large-scale integration (LSI) circuits, improvements of the power consumption by sensor scaling were proven. The pulsed operations required for integrated sensor arrays maintained a sensor response, or a resistance change, of approximately 60%, even when the power consumption was reduced by 20%. [ABSTRACT FROM AUTHOR]

The effects of the gate-induced field on sensor response in functionalized graphene sensor have not been fully understood yet. In this letter, graphene sensors decorated with Pd nanoparticles were fabricated, and gate voltage dependences of drain current and sensor response to hydrogen were experimentally and numerically examined. The sensor response was enhanced in the gate-induced electron conduction regime, compared to that in hole conduction regime. By utilizing the non-equilibrium Green’s function calculations, the origin of the response enhancement was modeled as asymmetric potentials for holes and electrons. We conclude that the sensor response of graphene can be enhanced using the gate-induced electric field in various types of graphene sensors. [ABSTRACT FROM AUTHOR]

The temperature dependence of the mobility of the two-dimensional electron gas (2DEG) in a silicon quantum well strained by Si0.7Ge0.3 relaxed buffer layer is determined precisely by a mobility spectrum analysis. The 2DEG mobility is 2780 cm2/V s at room temperature and, upon cooling, increases continuously to reach μ2DEG=7.4×104cm2/Vs at 7 K. A back gate installed on the sample changes the 2DEG concentration n successfully to establish μ2DEG∝n1.4 at the constant temperature T=10K, implying that the scattering at such low temperature is limited solely by the remote ionized impurity scattering. Based on this finding, theoretical analysis of the temperature dependence of μ2DEG is performed based on the relaxation time approximation using 2DEG wavefunctions and subband structures determined self-consistently and including three major scatterings; by intravalley acoustic phonons, intervalley g-processes of longitudinal optical (LO) phonons, and remote ionized impurities. The calculation included only three fitting parameters, the shear deformation potential (Ξu=9.5eV), LO phonon deformation potential for g-process scattering (D0=9.0×108eV/cm), and sheet density of remote ionized impurities that have been determined by quantitative comparison with our experimental results. The temperature dependence of μ2DEG calculated theoretically show excellent agreement with experimentally determined μ2DEG. [ABSTRACT FROM AUTHOR]

Papillary fibroelastoma (PFE) is a benign tumor that arises mostly from left-sided valves. PFE can cause stroke, and surgical resection may be needed. Lambl's excrescence (LE) is a filiform valvular lesion and is considered a possible cause of stroke. A 79-year-old man with light-headedness and left-sided hemiparesis was diagnosed with stroke. Transesophageal echocardiography (TEE) revealed a round-shaped mobile mass in the left ventricular outflow tract (LVOT), which was considered the cause of the stroke. Surgical resection was performed transaortically, and during surgery, a mass was incidentally detected on the noncoronary cusp (NCC), which was also resected followed by aortic valve replacement. Pathology confirmed that the mass in the LVOT was a PFE and that the filiform mass on the NCC was LE. We herein report a rare case of PFE in the LVOT and coexisting LE on the NCC. A careful examination via TEE helps to identify other possible causes of stroke hidden behind the obvious cause.

The continuous monitoring of hydrogen sulfide (H 2 S) in exhaled breath enables the detection of health issues such as halitosis and gastrointestinal problems. However, H 2 S sensors with high selectivity and parts per billion-level detection capability, which are essential for breath analysis, and facile fabrication processes for their integration with other devices are lacking. In this study, we demonstrated Au nanosheet H 2 S sensors with high selectivity, ppb-level detection capability, and high uniformity by optimizing their fabrication processes: (1) insertion of titanium nitride (TiN) as an adhesion layer to prevent Au agglomeration on the oxide substrate and (2) N 2 annealing to improve nanosheet crystallinity. The fabricated Au nanosheets successfully detected H 2 S at concentrations as low as 5.6 ppb, and the estimated limit of detection was 0.5 ppb, which is superior to that of the human nose (8-13 ppb). In addition, the sensors detected H 2 S in the exhaled breath of simulated patients at concentrations as low as 175 ppb while showing high selectivity against interfering molecules, such as H 2 , alcohols, and humidity. Since Au nanosheets with uniform sensor characteristics enable easy device integration, the proposed sensor will be useful for facile health checkups based on breath analysis upon its integration into mobile devices.

The Pt-Rh thin-film sensors exhibit excellent sensitivity and selectivity for H 2 gas detection. Here, we studied the mechanism of highly selective detection of H 2 by the Pt-Rh thin-film sensors with ambient-pressure X-ray photoelectron spectroscopy (AP-XPS) measurements at working conditions, which were paralleled with electric resistivity measurements. The elemental composition and chemical state of surface Pt and Rh drastically change depending on the background gas environments, which directly link to the sensor response. It is revealed that surface segregated Pt atoms accelerate dissociative adsorption of H 2 , resulting in a reduction of the sensor surface and then a decrease of electric resistivity of the film, whereas a thin oxidized Rh layer blocks dissociation of the other reducing agent, that is, NH 3 . This is supported from the adsorption energetics obtained by the density functional theory (DFT) calculations.

The sensing of gas components in a mixed gas is required for breath-based health monitoring and diagnosis. In this work, we report the simultaneous detection of mixed-gas components using a sensor consisting of [EMIM][BF 4 ]-based ionic gel with four electrodes made of Au, Pt, Rh, and Cr. The voltage between any given pair of electrodes depends on the gas molecules absorbed in the ionic gel and the elements the electrodes are made of. When the voltage signals between all pairs of electrodes were used, H 2 , NH 3 , and C 2 H 5 OH concentrations were simultaneously estimated by a neural-network-based inference. From molecular dynamics simulations, the origin of the voltage signal was attributed to the catalytically generated adsorbates on the electrodes.

In situ ambient-pressure X-ray photoelectron spectroscopy (AP-XPS) combined with resistivity measurement was performed for a Pt thin-film H2 gas sensor. We experimentally demonstrate that the chemical state of the Pt surface changes under working conditions, and it directly links to the sensing performance. Moreover, the operating principle is discussed at the atomic scale.

Objective: Proteinuria is a marker for cardiovascular diseases and all-cause mortality. In the Specific Health Checkups in Japan, when subjects show trace proteinuria (grade±) on dipstick assay, further examination is recommended to them. Although 150 mg/gCr is a threshold for diagnosing chronic kidney disease (CKD), little data on the relationship between dipstick grade± and the protein-creatinine ratio have been reported., Methods: A cross-sectional study using urine specimens obtained in a single institute, JCHO Saitama Northern Medical Center, was performed from October 2014 to March 2016. The level of proteinuria was measured in fresh morning urine samples from 819 volunteer participants of the Specific Health Checkups by two methods: Eiken Uropaper III to detect and qualitatively grade proteinuria, and total protein concentration by the pyrogallol red method., Results: Sensitivity, specificity, and the positive likelihood ratio to detect proteinuria of 30 mg/dL by 1+ were 90.3%, 97.8%, and 41.9, whereas 150 mg/gCr by ± were 45.3%, 81.4%, and 2.4, respectively. Therefore, screening for 150 mg/gCr by dipstick grade± had a false-negative rate of 54.7% and false-negative rate was significantly higher in women (8.0%) than in men (1.7%) (p < 0.0001)., Conclusions: Although the dipstick assay is useful to detect clinically significant proteinuria, substantial numbers of false-negative results occur in checkups for identifying subjects with a risk of CKD.

Understanding the dopant properties in heavily doped nanoscale semiconductors is essential to design nanoscale devices. We report the deionization or finite ionization energy of dopants in silicon (Si) nanofilms with dopant concentration (ND) of greater than 10(19) cm(-3), which is in contrast to the zero ionization energy (ED) in bulk Si at the same ND. From the comparison of experimentally observed and theoretically calculated ED, we attribute the deionization to the suppression of metal-insulator transition in highly doped nanoscale semiconductors in addition to the quantum confinement and the dielectric mismatch, which greatly increase ED in low-doped nanoscale semiconductors. Thus, for nanoscale transistors, ND should be higher than that estimated from bulk Si dopant properties in order to reduce their resistivity by the metal-insulator transition.

A 34-year-old Japanese woman presented at our institution weighing 182.7 kg, 148.2 cm tall, and with a body mass index of 83.2 kg/m(2). She had been overweight since childhood, but no abnormality was found to explain her obesity. Treatments, including mazindol, bofu-tsusho-san, dietary restriction, and BioEnterics Intragastric Balloon, did not result in improvement of her obesity. Finally, we performed sleeve gastrectomy, and she has maintained her weight within 130-140 kg without rebounding for 2 and a half years. We followed the clinical changes before and after the operation. This case provides potentially interesting information regarding operative treatment for morbid obesity in Japanese.

The prevalence of diabetes is increasing globally. In addition to established risk factors for diabetes, such as diet, inactivity, overweight and obesity, the involvement of persistent organic pollutants, including dioxins and polychlorinated biphenyls (PCBs), has also been suggested to be a possible, but controversial, cause of this epidemic. The present study investigated the association between blood PCB congener levels and the prevalence of diabetes among middle-aged, overweight and obese Japanese participants in the Saku Control Obesity Program. One hundred seventeen participants had their congener-specific PCB levels measured in addition to undergoing routine blood analyses at the time of a medical checkup. Prevalent diabetes was defined according to two methods: definite diabetes was defined as people with an HbA1c level ≥ 6.9% or who were taking medication for diabetes, and all diabetes was defined as people with an HbA1c level ≥ 6.5%, a fasting plasma glucose level ≥ 126 mg/dL, or a history of doctor-diagnosed diabetes. A multiple logistic regression analysis was performed to analyze the association between the PCB levels and the prevalence of diabetes, with adjustments for sex, age, body mass index and total lipids. As a result, PCB 146 and 180 were positively associated and PCB 163/164 and 170 were negatively associated with the prevalence of definite diabetes. The significance of the association of PCB 180 and 163/164 with the prevalence of diabetes persisted regardless of the definition of diabetes or adjustments for total lipids, suggesting the possibility that these parameters may modify the risk of diabetes., (©The Japan Endocrine Society)

Glycohemoglobin, also known as hemoglobin (Hb) A(1c), is a marker of long-term glycemic control in patients with diabetes. We present two South-Asian diabetic patients whose HbA(1c) peaks were not measurable using high performance liquid chromatography (HPLC). Further investigations showed that these patients were homozygous for a hemoglobin variant, HbE (beta26 Glu-->Lys). Because of the increasing numbers of immigrants in Japan, area-specific hemoglobinopathies are now encountered more frequently than before. Thus, if discrepant results are found on an HbA(1c) assay or if the HbA(1c) value cannot be measured, such patients should be screened for hemoglobinopathies and alternative measurements for monitoring diabetes should be considered.

Objective: To evaluate the results of treatment with an insulin glargine-based regimen as compared with those of an NPH insulin-based regimen., Methods: We reviewed the charts of 83 Japanese patients with Type 1 diabetes treated with insulin glargine for 12 months., Patients: Median age, 56.9 years (range, 24.6-74.8 years), mean (+/-S.D.) body mass index, 21.2 (+/-2.2) kg/m2., Results: The average HbA1c level of the cohort was 7.8 +/- 1.2% at baseline and 7.7 +/- 1.0% at the end of the 12-month treatment (P=0.34). The average insulin requirement per day in the cohort remained unchanged after the 12-month treatment (35.0 +/- 11.6 units/day versus 35.2 +/- 11.2 units/day (P=0.58). Of the 36 patients who were receiving twice or three times daily injections of NPH insulin, 30 could be switched to a single-daily injection of insulin glargine. The frequency of severe hypoglycemia with unconsciousness became lower after switching to the insulin glargine-based regimen than during treatment with the NPH-based regimen. The average ratio of the daily usage of insulin glargine to that of total insulin after 12 months was smaller than that reported from other countries (0.34 +/- 0.09)., Conclusion: These results obtained from a larger number of patients as compared to previous Japanese studies confirm earlier reports that insulin glargine provides equivalent glycemic control to human NPH insulin, with a lower incidence of severe hypoglycemia. Thus, treatment with insulin glargine provides some benefits to Japanese patients with Type 1 diabetes.