Large Leakage Research Articles

Inhibition of tau amyloid formation and disruption of its preformed fibrils by Naphthoquinone-Dopamine hybrid.

Misfolding and aggregation of tau protein, into pathological amyloids, are hallmarks of a group of neurodegenerative diseases collectively termed tauopathies and their modulation may be therapeutically valuable. Herein, we describe the synthesis and characterization of a dopamine-based hybrid molecule, naphthoquinone-dopamine (NQDA). Using thioflavin S assay, CD, transmission electron microscopy, dynamic light scattering, Congo Red birefringence, and large unilamellar vesicle leakage assays, we demonstrated its efficacy in inhibiting the invitro aggregation of key tau-derived amyloidogenic fragments, PHF6 (VQIVYK) and PHF6* (VQIINK), prime drivers of aggregation of full-length tau in disease pathology. Isothermal titration calorimetry analysis revealed that the interaction between NQDA and PHF6 is spontaneous and has significant binding efficiency driven by both entropic and enthalpic processes. Furthermore, NQDA efficiently disassembled preformed fibrils of PHF6 and PHF6* into nontoxic species. Molecular dynamic simulations supported the invitro results and provided a plausible mode of binding of NQDA with PHF6 fibril. NQDA was also capable of inhibiting the aggregation of full-length tau protein and disrupting its preformed fibrils invitro in a dose-dependent manner. In a comparative study, the IC50 value (50% inhibition of fibril formation) of NQDA in inhibiting the aggregation of PHF6 (25µm) was ~17µm, which is lower than for other bona fide amyloid inhibitors, naphthoquinone-tryptophan, rosmarinic acid, epigallocatechin gallate, ~21, ~77, or ~19µm, respectively. Comparable superiority of NQDA was observed for inhibition of PHF6*. These findings suggest that NQDA can be a useful scaffold for designing new therapeutics for Alzheimer's disease and other tauopathies.

Highly isolated switching mode power supply for solid-state transformers in railway vehicles

This paper discusses an isolated switching mode power supply (SMPS) with an AC 30 kVrms insulation capability for application to the solid-state transformers (SSTs) in railway vehicles. The insulation capability of the SMPS should be higher than AC 25 kVrms for application at the SSTs in railway vehicles. The proposed highly isolated SMPS is superior to commercial isolated power supplies with low insulation capability, which is normally less than 20 kV. The input side of the proposed isolated SMPS is physically separated from its output side by a specially designed miniature high-frequency (HF) transformer to obtain high insulation capability. The core of the miniature HF transformer is separated by insulation material. The primary and secondary coils are wound around each separated core. A CLLC resonant converter that consists of a primary resonant capacitor (C), two inductors (LL), and a secondary resonant capacitor (C) is applied as the proposed isolated SMPS topology to improve the output voltage regulation performance, which varies due to a large leakage inductance derived from the airgap of the proposed miniature HF transformer. Experiments are carried out to verify the CLLC resonant converter of the proposed isolated SMPS. Electrostatic finite element method (FEM) simulations and high potential (HiPot) tests are carried out to verify the AC 30 kVrms insulation capability of the proposed isolated SMPS. The electrostatic FEM simulations demonstrate the DC 42.43 kV insulation capability, and the HiPot tests verify the insulation capability from AC 5 kVrms to AC 30 kVrms.

Effects of Al Composition and High-Temperature Atomic Layer-Deposited Al2O3 Layer on the Leakage Current Characteristics of AlGaN/GaN Schottky Barrier Diodes

AlGaN/GaN Schottky barrier diodes (SBDs) with high Al composition and high temperature atomic layer deposition (ALD) Al2O3 layers were investigated. Current–voltage (I–V), X-ray photoelectron spectroscopy (XPS), atomic force microscope (AFM), and capacitance–voltage (C–V) measurements were conducted in order to find the leakage current mechanism and reduce the reverse leakage current. The fabricated AlGaN/GaN SBDs with high Al composition exhibited two orders’ higher leakage current compared to the device with low Al composition (20%) due to large bulk and surface leakage components. The leakage current measured at −60 V for the fabricated SBD with Al2O3 deposited at temperature of 550 °C was decreased to 1.5 μA, compared to the corresponding value of 3.2 mA for SBD with nonpassivation layer. The high quality ALD Al2O3 deposited at high temperature with low interface trap density reduces the donorlike surface states, which effectively decreases surface leakage current of the AlGaN/GaN SBD.

Device and Circuit Exploration of Multi-Nanosheet Transistor for Sub-3 nm Technology Node

A multi-nanosheet field-effect transistor (mNS-FET) device was developed to maximize gate controllability while making the channel in the form of a sheet. The mNS-FET has superior gate controllability for the stacked channels; consequently, it can significantly reduce the short-channel effect (SCE); however, punch-through inevitably occurs in the bottom channel portion that is not surrounded by gates, resulting in a large leakage current. Moreover, as the size of the semiconductor device decreases to several nanometers, the influence of the parasitic resistance and parasitic capacitance increases. Therefore, it is essential to apply design–technology co-optimization, which analyzes not only the characteristics from the perspective of the device but also the performance from the circuit perspective. In this study, we used Technology Computer Aided Design (TCAD) simulation to analyze the characteristics of the device and directly fabricated a model that describes the current–voltage and gate capacitance characteristics of the device by using Berkeley short-channel insulated-gate field-effect transistor–common multi-gate (BSIM–CMG) parameters. Through this model, we completed the Simulation Program with Integrated Circuit Emphasis (SPICE) simulation for circuit analysis and analyzed it from the viewpoint of devices and circuits. When comparing the characteristics according to the presence or absence of bottom oxide by conducting the above research method, it was confirmed that subthreshold slope (SS) and drain-induced barrier lowering (DIBL) are improved, and power and performance in circuit characteristics are increased.

Trap Reduction through O3 Post‐Deposition Treatment of Y2O3 Thin Films Grown by Atomic Layer Deposition on Ge Substrates

AbstractFor Ge‐based metal‐oxide‐semiconductor field‐effect transistor application, high‐k Y2O3 thin films are deposited on Ge single‐crystal substrate using atomic layer deposition. The primary drawbacks of a metal‐oxide‐semiconductor capacitor with pristine Y2O3 are large hysteresis and high leakage current. Through forming gas annealing (FGA), the leakage current can be reduced by approximately three orders of magnitude, along with the reduction of interface trap density. However, there is still a large hysteresis in the capacitance–voltage curves. O3 post‐deposition annealing (OPA) is used to solve the problem. The formation of the YGeOx interfacial layer through OPA and the reduction of the defect level of the Y2O3 thin film effectively decrease the hysteresis, which also decreases the leakage current. Additionally, the hysteresis is 690 mV when only FGA is performed. However, it is further reduced to 260 mV through OPA. Moreover, the remote oxygen scavenging effect using TiN/Pt electrodes prevents an unintentional increase in equivalent oxide thickness (EOT). The 4.7 nm thick Y2O3 film results in an EOT of 1.77 nm and leakage current density of 2.1 × 10−7 A cm−2 (at flat band voltage—1 V) after the OPA.

A Simulation Study on the Effects of Interface Charges and Geometry on Vertical GAA GaN Nanowire MOSFET for Low-Power Application

The effects of interface charges on the performances of gate-all-around (GAA) GaN vertical nanowire MOSFETs with different geometries have been studied. Geometrical effect on the gate current of vertical GAA GaN nanowire MOSFET has also been analysed for the first time. In the ideal condition, the circular geometry nanowire (CGN) MOSFET exhibits the best performance with subthreshold swing (SS) of 62 mV/dec, drain-induced barrier lowering (DIBL) of 14 mV/V, and ON/OFF current ratio ( I <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">ON</sub> /I <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">OFF</sub> ) of ~10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">8</sup> . The triangular or hexagonal geometry nanowire (TGN or HGN) MOSFET suffer from large gate leakage current due to the field enhancement at sidewall corners. It is also known that interface traps at the sidewall surface of vertical nanowires deteriorate the overall device performance. The HGN MOSFET with m-plane sidewall demonstrates the best performance with SS of 69 mV/dec and DIBL of 13 mV/V, while the TGN MOSFET with a-plane sidewall exhibits the worst performance with SS of 112 mV/dec and DIBL of 101 mV/V.

High yield uniformity in pseudo-vertical diamond Schottky barrier diodes fabricated on half-inch single-crystal wafers

We fabricated diamond pseudo-vertical Schottky barrier diodes using a half-inch semi-insulative diamond (100) wafer. Most diodes exhibited a large rectifying ratio (&amp;gt;1010) with undetectable leakage current at a reverse bias of 5 V (0.6 MV cm−1), with only 2% of diodes exhibiting an Ohmic-like leakage current. Surface defects were observed under the Schottky barrier diode, and their impacts on electrical properties were analyzed using a Murphy model and correlation factor analysis. We found that most crystalline defects (surface hillocks) were electrically non-active and that non-epitaxial crystallites and process-related field-plate cracks were the main defects that induced a large leakage current. Schottky barrier diodes without such killer defects showed a high electric field strength of ∼5 MV cm−1.

Experimental Study on Leak Detection and Location for Gas Pipelines Based on Acoustic Waves Using Improved Hilbert–Huang Transform

Pipeline systems are a safe method of transporting oil and gas from one place to another, although they suffer from leaks due to external and internal factors and fail to deliver the required products to customers. Many methods have been researched and implemented for gas leakage detection and localization. However, larger leakages can be easily detected while small leakages may not be detected for some time, especially when a pipeline is buried in remote places or under ice. Therefore, lacking real-time small and larger gas leakage wireless sensor detection systems causes financial, environmental, and health problems. In this paper, an experimental study has been conducted for real-time natural gas leakage detection and localization based on acoustic waves. Surface acoustic sensor technology and Hilbert–Huang transform (HHT) processing algorithm were successfully studied both experimentally and numerically to discover their efficiency on leakage detection and localization, and they are proposed and established as the best method for gas pipeline leak detection. A small gas pipe section with 40-m length, 20-mm internal diameter, and two valves as the artificial leaks was used. First, the leakage detection and location method based on an acoustic wave with an improved HHT method and the propagation model were suggested and designed. When the two key points were established, the experiential equipment was constructed on a laboratory scale and the experiments were conducted. The time difference (TD) was calculated, and the propagation model and the leakage localization methods were also verified. Finally, the results of the experiments are discussed and analyses indicate the improved HHT method and the HHT method yield different experimental leak location error maximum absolute values of 0.58% and 13.66%, respectively, showing that an improved HHT method is better than the HHT method for calculating the TD of leakage location; the method based on the amplitude propagation model can be achieved without TD calculation. Therefore, it is concluded that the new method is efficient and can protect and monitor natural gas pipelines.

Hysteresis of Percolation Transition and Relaxation of Fast and Slow States of the System Nanoporous Medium - Non-Wetting Liquid

In the present paper we present the results of experimental and theoretical studies of intrusion-extrusion and relaxation of non-wetting liquid in three Fluka porous media. New data on hysteresis of intrusion-extrusion and dependence of the degree of filling of a porous body on time in the process of extrusion were obtained experimentally. It has been established that in all the conducted experiments the liquid extrusion took place in two stages: at the first stage of fast relaxation the characteristic time of outflow is several seconds, at the second stage of slow relaxation the characteristic time is several hundred seconds. The experimental data obtained are described in the theoretical model [1]. For the studied porous media, the existence at the initial moment of time of local states with short leakage times (a few seconds or less) and states with large leakage times (hundreds of seconds) was established. Porous bodies in which the coexistence of fast and slow states at the initial moment of time is established are investigated for the first time.

A sub-500 mV monolayer hexagonal boron nitride based memory device

The recent discovery of memristive devices based on two-dimensional materials have attracted much interest for emerging applications on flexible memory, neuromorphic computing, and so forth. Reducing the thickness to a single-layer level would prompt the scaling limit to sub-nanometer. However, monolayer materials based vertical memristive devices generally suffer inferior performance with high operating voltage, large leakage currents, and poor reliability. In this study, an interfacial polymer layer is inserted between the monolayer hexagonal boron nitride (h-BN) and top electrodes, which not only helps to constrain the conducting filament size but also block the formation of excess filaments from the bottom Cu foil. Therefore, the device shows stable bipolar resistive switching behavior with low operating voltage (< 500 mV), large on/off ratio (up to 105), long retention time (> 105 s), and excellent flexibility. It is demonstrated that tunneling conduction is shown in off-state and on-state current conducts via metallic conducting filaments, which are formed by the substitute of metal ions for lattice vacancies in h-BN. This work presents a scalable interface engineering strategy to control the interactions between metal ions and defects in monolayer h-BN films and sheds light on their promising application for large-scale integrated ultrathin flexible memory.

The Gate Cut Process Window Discussion

The technology of FinFET has led to the continuity of device scaling and enabled the prolongation of Moore’s Law towards the 7 nm and beyond nodes. The gate cut last has been widely adopted since it can provide better SiP/SiGe growth environment, hence yielding the better electrical performance. However, This approach requires a higher level of defect control.As we all know, the first task of gate cut is to completely cut off the gate, so that the metal gate that do not need to be connected can realize electrical separation. If good electrical insulation can not be achieved, there will induce a large leakage, so that the working voltage is increased. However, due to the miniaturization of the size, the distance between the end of the metal gate and the effective Fin is very short, which requires that the gate cutting can not only achieve electrical isolation through the size increase. The filling and patterning of the various materials of the metal gate must be considered. On the other hand, defect control is also critical for many special structures, such as gate ends formed by SaDP and gate cutting with special relationship to Fin.This paper focuses on defect issues related to gate cutting in FinFET. It mainly includes: the first, some common defects related to gate cutting itself, such as the absence of cutting pattern caused by etch bias in dense and iso areas, the mutation of gate cutting pattern caused by stress introduction, and the gate bridge caused by tapered bottom profile, etc. The second, defect issues caused by gate cutting size affecting other manufacturing processes, such as residue generated by HKMG pattering, dummy poly gate residue, capping layer residue, single diffusion break induce metal gate bridge, etc. The third, defect issue of a structure that has a special relationship to the gate cut pattern, gate line end bridge, etc. In this article, we will discuss these typical defect issues in detail to gain a better understanding of the gate cut process. By understanding these defects, we can better control the metal gate cut process and maximize the process window.

Virtual refrigerant charge sensor for booster refrigeration systems

Abstract In this paper a virtual refrigerant charge sensor (VRCS) for a booster refrigeration system with a receiver unit is developed and proposed. The VRCS estimates the liquid charge in the receiver unit by utilizing a combined mass and energy balance equation for mapping the change in the receiver unit’s time constant to the liquid volume in the receiver unit. The time constant for the receiver unit is found by utilizing the commonly available data in an online subspace identification method. The parameters estimated by the online subspace identification method are recast in a linear fractional transformation structure to identify parameter changes due to liquid volume change. Hence, the VRCS functions in a plug and play framework where only the initial refrigerant charge in percentage is required to be known. Results from utilizing the VRCS on experimental data from a charge test conducted on a test setup located at Danfoss A/S are shown, where the VRCS shows an accurate estimation of the liquid charge in the receiver. The results from the VRCS can be employed for: early prediction of low charge in the system, early detection of a too large leakage rate, estimation of the current charge on a daily basis, and estimation of the amount of charge lost.

Numerical Simulation and Analysis of Diffusion Process for the Leakages of a Tunnel LNG Pipeline

Taking a practical project as an example, based on the computational fluid dynamics (CFD), standard k-ε model and finite element method, a mathematical model for the diffusion due to liquefied natural gas (LNG) pipeline leakage in a tunnel was established, and the diffusion process was numerically simulated for three LNG leakage cases. From the simulation results, the variation of CH4 concentration field and explosive gas cloud with time within the tunnel, and the influence of leakage location on the diffusion was analyzed for the three cases. It was shown that the variation of CH4 concentration field had a similar trend for the three cases, but the CH4 explosive gas cloud length increased rapidly with the LNG leakage intensity so that dangerous situations would occur for the medium and large leakages, and a leak location closer to air inlet would lead to a more dangerous situation. When the amount of LNG leakage in the tunnel is large, the effect of mechanical ventilation is obviously weakened. Furthermore, a nitrogen seal precaution was proposed for the situations.

Fluid Leakage in Metallic Seals

Metallic seals are crucial machine elements in many important applications, e.g., in ultrahigh vacuum systems. Due to the high elastic modulus of metals, and the surface roughness which exists on all solid surfaces, if no plastic deformation would occur one expects in most cases large fluid flow channels between the contacting metallic bodies, and large fluid leakage. However, in most applications plastic deformation occurs, at least at the asperity level, which allows the surfaces to approach each other to such an extent that fluid leakage often can be neglected. In this study, we present an experimental set-up for studying the fluid leakage in metallic seals. We study the water leakage between a steel sphere and a steel body (seat) with a conical surface. The experimental results are found to be in good quantitative agreement with a (fitting-parameter-free) theoretical model. The theory predicts that the plastic deformations reduce the leak-rate by a factor approx 8.

Study of Shallow Groundwater in Al-Diwaniya City / South Iraq

Al-Diwaniya city suffers from shallow groundwater levels, which cause serious problems on the foundation of builds in the area and affect the general health of citizens in residential areas. For investigating this problem, four different paths perpendicular to Shatt Al- Diwaniya were selected, along 11 hand-dug wells in the city to observe groundwater levels during a whole year (2019-2020). The work included observation boreholes water levels and comparing results with water levels in the Shatt al-Diwaniya. Along each of the four selected paths (A, B, C, and D), two boreholes are observed on each side of the Shatt al-Diwaniya. Depths of boreholes are from 6 to 12 m. All boreholes paths that represent shallow groundwater within residential districts. The water level of Shatt Al-Diwaniya and groundwater levels is monitored twice-per-month, especially over high and low water conditions within Shatt Al-Diwaniya. Hydrometric results showed a relationship between shallow groundwater and Shatt Al-Diwaniya levels in track A. The nature of this interaction along with the track A due to many local factors such as depth of water in Shatt Al-Diwaniya, amount of rainfall, factors of high water levels, conditions and climatic changes, soil factors and the current state of the deterioration of the sewage network in Diwaniya city. Finally, the results of the rest tracks indicated that the city is flooded with shallow groundwater due to the large sewage leakage in addition to the rainwater and that Shatt Al-Diwaniya does not affect groundwater in the area. Still, it works discharge groundwater in the city.

Strengthened Complementary Metal-Oxide-Semiconductor Logic for Small-Band-Gap Semiconductor-Based High-Performance and Low-Power Application.

Silicon-based complementary metal-oxide-semiconductor (CMOS) has been the mainstream logic style for modern digital integrated circuits (ICs) for decades but will meet its performance limits soon. Extensive investigations have thus been carried out using other semiconductors, especially those with extremely high carrier mobility. However, these materials usually have small or even zero band gap, which leads inevitably to large leakage current or voltage loss in ICs based on these semiconductors. In this work, we propose and demonstrate a strengthened CMOS (SCMOS) logic style using modified field-effect transistors (FETs) to solve this problem, that is, to achieve high performance, utilizing the high carrier mobility in these materials, and to reduce the current leakage resulting from their small band gap. Conventional CMOS FETs are modified to have an asymmetric structure where an additional assistant gate is introduced near the drain to further lower the potential barrier in on-state and to increase the barrier in off-state. SCMOS ICs are constructed using these modified asymmetric CMOS FETs, which demonstrate perfect rail-to-rail output with negligible voltage loss and 3 orders of magnitude suppression of the static power consumption and an operating speed similar to or even higher than that of CMOS ICs. Here, SCMOS is demonstrated using carbon nanotubes, but, in principle, this logic style can be used in ICs based on any small-band-gap semiconductors to provide simultaneously high performance and low power consumption.

Ion-Exchange Separators Suppressing Self-Discharge in Polymeric Supercapacitors

Author(s): Wang, K; Yao, L; Jahon, M; Liu, J; Gonzalez, M; Liu, P; Leung, V; Zhang, X; Ng, TN | Abstract: Supercapacitors offer superior cycle life and high power densities, but as energy storage devices, they are limited by self-discharge processes manifested as large potential decay and leakage current, resulting in loss of stored energy and low charging efficiency. To minimize Faradaic side reactions, this Letter has incorporated a sulfonate ion-exchange resin in separators to trap impurities and thereby suppress self-discharge in supercapacitors with PEDOT as redox electrodes. The versatile separator design is generally applicable to organic and aqueous electrolytes and compatible with a pH range of 0-14, while maintaining the device capacitance and rate performance. Temperature-dependent characteristics were analyzed to identify that the reduction of impurity concentration and diffusion was key to improve potential retention. Compared to devices using commercially available separators, the device here exhibited a lower leakage current and better charging efficiency. It was demonstrated to work with radio frequency energy-harvesting circuits and showed the potential to serve as an energy reservoir for wireless electronic applications.

Impact of dislocation pits on device performances and interface quality degradation for E-mode recessed-gate Al2O3/GaN MOSFETs

The degradation of device electrical characterizations and MOS interfacial quality caused by dislocation pits on recessed-gate GaN surface are directly observed and investigated for e-mode Al2O3/GaN MOSFETs on Si substrate. The pits have resulted in negative shift of threshold voltage (Vth), large gate leakage current and deteriorated channel conduction. Moreover, the serious gate trapping effects reflected in Vth instability are confirmed to be correlated with these pits. It has been mainly attributed to the formation of poor-quality MOS interface with high density of interface traps more than 1013 cm−2eV−1. Further experimental measurements reveal that the pits tend to induce detrimental Ga–O on the recessed GaN surface, generally known as a common origin of interface traps, and thus cause the undesirable effects. A lower pits density helps to suppress the Ga–O, and improve the interface stability and device performances of e-mode MOS-gate GaN transistors.

Design of a rear-stage subsonic axial compressor with casing treatments

The aerodynamic design of a 3.5-stage high-pressure axial compressor, representing a modern rear stage design with low aspect ratio blades and large relative tip gaps is presented. The subsonic rotor and stator airfoils feature a controlled-diffusion (CDA) type of sectional design, obtained from 2D viscous-inviscid simulations using the MISES flow solver. Improvements of the main gas path, as well as the 3D blade design, are based on 3D steady Reynolds-averaged Navier–Stokes simulations (ANSYS CFX). Sweep and dihedral were applied to improve the design and off-design performance of the compressor. The matured set of blading, with smooth casing, still exhibits large rotor tip vortices and double leakage, limiting the compressors operability towards stall point. Consequently, the application and development of axial slot casing treatments (CT) into the smooth casing is performed, aimed at improving local stage and overall stall margin with particular emphasis on avoiding efficiency penalties within stages. In order to investigate and optimise the geometric properties of the CTs with respect to efficiency a DoE (Design of Experiments) is executed. Based on the DoE a CT-geometry is deduced and applied to the critical rotor. Due to the fact, that the stage operability with casing treatment is limited by the downstream stator, a first adaption of the existing blade design is considered. In a first step, the downstream stator’s incidence is adjusted, resulting in a slightly increased stall margin. The second step incorporates the modification of rotor blade count, following the idea of trading rotor operability for an efficiency increase, due to reduced friction. However, no notable efficiency benefit was achieved, as the reduced friction loss is counterbalanced by increased secondary flow loss resulting from higher blade loadings.

Electrical characteristics of SnO2 voltage-sensitive ceramics doped with Ni2O3

SnO2 voltage-sensitive ceramics is a kind of ceramic with nonlinear characteristics, which is the most promising new material for high voltage and large current varistors. At present, the SnO2 varistors still have the problems of large leakage current and relatively low nonlinear coefficient. For the low leakage current and high nonlinear coefficient of the varistors, in this paper, the influence of different amounts of Ni2O3 on the electrical properties and microstructure of SnO2·MnO2·ZnO·Ta2O5 system was studied. The formation mechanism of the electrical characteristics of SnO2 varistors was studied by measuring current-voltage, SEM, capacitor-voltage, X-ray diffraction and ac impedance spectra of the samples. It was found that the electrical characteristics of the samples were the best (the voltage gradient was 563V/mm, the leakage current was 8.87 μA/cm2, the nonlinear coefficient was 38.5), when 0.2 mol % Ni2O3 was added. This study has reference significance for exploring SnO2 varistor with high nonlinear and low leakage current.