Plasmonic Terahertz Wave Detector Based on Silicon Field-Effect Transistors with Asymmetric Source and Drain Structures

In this paper, we present the validity and potential capacity of a modeling and simulation environment for the nonresonant plasmonic terahertz (THz) detector based on the silicon (Si) field-effect transistor (FET) with a technology computer-aided design (TCAD) platform. The nonresonant and "overdamped" plasma-wave behaviors have been modeled by introducing a quasi-plasma electron charge box as a two-dimensional electron gas (2DEG) in the channel region only around the source side of Si FETs. Based on the coupled nonresonant plasma-wave physics and continuity equation on the TCAD platform, the alternate-current (AC) signal as an incoming THz wave radiation successfully induced a direct-current (DC) drain-to-source output voltage as a detection signal in a sub-THz frequency regime under the asymmetric boundary conditions with a external capacitance between the gate and drain. The average propagation length and density of a quasi-plasma have been confirmed as around 100 nm and 1x10(19)/cm(3), respectively, through the transient simulation of Si FETs with the modulated 2DEG at 0.7 THz. We investigated the incoming radiation frequency dependencies on the characteristics of the plasmonic THz detector operating in sub-THz nonresonant regime by using the quasi-plasma modeling on TCAD platform. The simulated dependences of the photoresponse with quasi-plasma 2DEG modeling on the structural parameters such as gate length and dielectric thickness confirmed the operation principle of the nonresonant plasmonic THz detector in the Si PET structure. The proposed methodologies provide the physical design platform for developing novel plasmonic THz detectors operating in the nonresonant detection mode.open3

Coulomb oscillations based on band-to-band tunneling in a degenerately doped silicon metal-oxide-semiconductor field-effect transistor

The Coulomb oscillations based on band-to-band tunneling through a valence band in silicon metal-oxide-semiconductor field-effect-transistors were discussed. It was found that the formation of tunnel barries and a quantum dot in a single-electron transistor structure originated from two p+ - p+ tunnel junctions and a p+ -doped channel with mesoscopic dimension, respectively. At liquid nitrogen temperature, the Coulomb-blockade oscillations with multiple peaks were also observed. Analysis shows that the single-electron charging effect based on band-to-band tunneling was confirmed using the electrical and thermal characterization of the quantum dots.open2

Silicon-compatible high-hole-mobility transistor with an undoped germanium channel for low-power application

In this work, Ge-based high-hole-mobility transistor with Si compatibility is designed, and its performance is evaluated. A 2-dimensional hole gas is effectively constructed by a AlGaAs/Ge/Si heterojunction with a sufficiently large valence band offset. Moreover, an intrinsic Ge channel is exploited so that high hole mobility is preserved without dopant scattering. Effects of design parameters such as gate length, Ge channel thickness, and aluminum fraction in the barrier material on device characteristics are thoroughly investigated through device simulations. A high on-current above 30 ??A/??m along with a low subthreshold swing was obtained from an optimized planar device for low-power applications.open0

Interferometric Imaging, and Beam-Formed Study of a Moving Type-IV Radio Burst with LOFAR

Type-IV radio bursts have been studied for over 50 years. However, the specifics of the radio emission mechanisms is still an open question. In order to provide more information about the emission mechanisms, we studied a moving Type-IV radio burst with fine structures (spike group) by using the high-resolution capability of the Low-Frequency Array (LOFAR) on August 25, 2014. We present a comparison of Nançay Radioheliograph (NRH) and the first LOFAR imaging data of the Type-IV radio burst. The degree of circular polarization (DCP) is calculated at frequencies in the range 20 — 180 MHz using LOFAR data, and it was found that the value of DCP gradually increased during the event, with values of 20 — 30%. LOFAR interferometric data were combined with white-light observations in order to track the propagation of this Type-IV burst. The kinematics shows a westward motion of the radio sources, slower than the CME leading edge. The dynamic spectrum of LOFAR shows a large number of fine structures with durations of less than 1 s and high brightness temperatures (TB), i.e., 1012 — 1013 K. The gradual increase of DCP supports gyrosynchrotron emission as the most plausible mechanism for the Type IV. However, coherent emissions such as Electron Cyclotron Maser (ECM) instability may be responsible for small-scale fine structures. Countless fine structures altogether were responsible for such high TB.Peer reviewe

Crystal structures of murine norovirus-1 RNA-dependent RNA polymerase in complex with 2-thiouridine or ribavirin

AbstractMurine norovirus-1 (MNV-1) shares many features with human norovirus (HuNoV) and both are classified within the norovirus genus of Caliciviridae family. MNV-1 is used as the surrogate for HuNoV research since it is the only form that can be grown in cell culture. HuNoV and MNV-1 RNA dependent RNA polymerase (RdRp) proteins with the sequence identity of 59% show essentially identical conformations. Here we report the first structural evidence of 2-thiouridine (2TU) or ribavirin binding to MNV-1 RdRp, based on the crystal structures determined at 2.2Å and 2.5Å resolutions, respectively. Cellular and biochemical studies revealed stronger inhibitory effect of 2TU on the replication of MNV-1 in RAW 264.7 cells, compared to that of ribavirin. Our complex structures highlight the key interactions involved in recognition of the nucleoside analogs which block the active site of the viral RNA polymerase

Fabrication of single-electron tunneling transistors with an electrically formed Coulomb island in a silicon-on-insulator nanowire

For the purpose of controllable characteristics, silicon single-electron tunneling transistors with an electrically formed Coulomb island are proposed and fabricated on the basis of the sidewall process technique. The fabricated devices are based on a silicon-on-insulator (SOI) metal-oxide-semiconductor (MOS) field effect transistor with them depletion gate. The key fabrication technique consists of two sidewall process techniques. One is the patterning of a uniform SOI nanowire, and the other is the formation of n-doped polysilicon sidewall depletion gates. While the width of a Coulomb island is determined by the width of a SOI nanowire, its length is defined by the separation between two sidewall depletion gates which are formed by a conventional lithographic process combined with the second-sidewall process. These sidewall techniques combine the conventional lithography and process technology, and guaran tee the compatibility with complementary MOS process technology. Moreover, critical dimension depends not on the lithographical limit but on the controllability of chemical vapor deposition and reactive-ion etching. Very uniform weakly p-doped SOI nanowire defined by the sidewall technique effectively suppresses unintentional tunnel junctions formed by the fluctuation of the geometry or dopant in SOI nanowire, and the Coulomb island size dependence of the device characteristics confirms the good controllability. A voltage gain larger than one and the controllability of Coulomb oscillation peak position are also successfully demonstrated, which are essential conditions for the integration of a single-electron tunneling transistor circuit. Further miniaturization and optimization of the proposed device will make room temperature designable single-electron tunneling transistors possible in the foreseeable future.open101

Effects of Lowering Dialysate Calcium Concentrations on Arterial Stiffness in Patients Undergoing Hemodialysis

BACKGROUND/AIMS: We assessed changes in hemodynamic and arterial stiffness parameters following reductions of dialysate calcium concentrations in patients undergoing hemodialysis. METHODS: In this prospective study, 20 patients on maintenance hemodialysis (10 females, 10 males) with dialysate calcium concentrations of 1.75 mmol/L were enrolled. At the start of the study, the dialysate calcium level was lowered to 1.50 mmol/L. Serial changes in biochemical, hemodynamic, and arterial stiffness parameters, including pulse wave velocity (PWV) and augmentation index (AIx), were assessed every 2 months for 6 months. We also examined changes in the calcification-inhibitory protein, serum fetuin-A. RESULTS: During the 6-month study period, serum total calcium and ionized calcium decreased consistently (9.5 ± 1.0 to 9.0 ± 0.7, p = 0.002 vs. 1.3 ± 0.1 to 1.1 ± 0.1, p = 0.035). Although no apparent changes in blood pressure were observed, heart-femoral PWW (hf-PWV) and AIx showed significant improvement (p = 0.012, 0.043, respectively). Repeated-measures ANOVA indicated a significant effect of lowering dialysate calcium on hf-PWV (F = 4.58, p = 0.004) and AIx (F = 2.55, p = 0.049). Accompanying the change in serum calcium, serum fetuin-A levels significantly increased (95.8 ± 45.8 pmol/mL at baseline to 124.9 ± 82.2 pmol/mL at 6 months, p = 0.043). CONCLUSIONS: Lowering dialysate calcium concentration significantly improved arterial stiffness parameters, which may have been associated with upregulation of serum fetuin-A.ope

A standardized extract of Rhynchosia volubilis Lour. exerts a protective effect on benzalkonium chloride-induced mouse dry eye model

ETHNOPHARMACOLOGICAL RELEVANCE In contrast to other leguminous plants generally used as food, Rhynchosia volubilis Loureiro, a small soybean with a black seed coat, has been used as a traditional oriental remedy for various human diseases in Eastern Asia. In this study, we demonstrated the protective effect of R. volubilis against dry eye disease. AIM OF THE STUDY We aimed to investigate whether a standardized ethanol extract of R. volubilis (EERV) can protect the cornea in a benzalkonium chloride (BAC)-induced mouse dry eye model. MATERIALS AND METHODS Experimental dry eye was induced by the instillation of 0.2% BAC on mouse cornea. A standardized ethanol extract of R. volubilis (EERV) was orally administered following BAC treatment. The positive control group was treated with commercial eye drops. Fluorescein staining, tear break-up time (BUT), and hematoxylin and eosin staining were evaluated on the ocular surface. Squamous metaplasia and apoptosis in the corneal epithelial layer were detected by immunostaining. Furthermore, the protein expression of cytochrome c, Bcl-2, and Bax was determined. RESULTS EERV treatment significantly improved fluorescein scoring, BUT, and smoothness in the cornea compared to the vehicle group. In addition, EERV inhibited squamous metaplasia and apoptosis in the cornea. The expression of cytochrome c and Bax was upregulated, while that of Bcl-2 was downregulated in the vehicle group compared with that in the control group. However, EERV treatment inhibited the expression of cytochrome c and Bax, while that of Bcl-2 was improved. CONCLUSION Standardized EERV could be a beneficial candidate for the treatment of dry eye disease

Schwannoma in Head and Neck: Preoperative Imaging Study and Intracapsular Enucleation for Functional Nerve Preservation

PURPOSE: In treating schwannoma patients, it is critical to determine the origin of the tumor to preserve nerve function. We evaluated the validity of preoperative imaging studies in distinguishing the neurological origin of the schwannomas of the head and neck, and the efficacy of intracapsular enucleation in preserving nerve function. MATERIALS AND METHODS: In 7 cases of schwannomas in the head and neck region, we predicted whether the tumor originated from the vagus nerve or the cervical sympathetic chain through imaging studies including computed tomography (CT) and magnetic resonance imaging (MRI). All patients were performed intracapsular enucleation, and the function of the vagus nerve and the sympathetic nerve was evaluated preoperatively and postoperatively. RESULTS: Preoperative imaging studies showed 6 cases where the tumor was located between the carotid artery and the internal jugular vein, and 1 case where the tumor was located posteriorly, displacing the carotid artery and the internal jugular vein anteriorly. At the time of operation, we confirmed schwannoma originating from the vagus nerve on the first 6 cases, and schwannoma originating from the sympathetic nervous system on the last case. All patients went through successful intracapsular enucleation, and of the seven schwannoma cases, 6 patients maintained normal postoperative neurological function (85.7%). CONCLUSION: Preoperative imaging studies offer valuable information regarding the location and origination of the tumor, and intracapsular enucleation helped us to preserve the nerve function.ope