Defect spectroscopy of sidewall interfaces in gate-all-around silicon nanosheet FET.

Through time-dependent defect spectroscopy and low-frequency noise measurements, we investigate and characterize the differences of carrier trapping processes occurred by different interfaces (top/sidewall) of the gate-all-around silicon nanosheet field-effect transistor (GAA SiNS FET). In a GAA SiNS FET fabricated by the top-down process, the traps at the sidewall interface significantly affect the device performance as the width decreases. Compare to expectations, as the width of the device decreases, the subthreshold swing (SS) increases from 120 to 230 mV/dec, resulting in less gate controllability. In narrow-width devices, the effect of traps located at the sidewall interface is significantly dominant, and the 1/f 2 noise, also known as generation-recombination (G-R) noise, is clearly appeared with an increased time constant (τ i ). In addition, the probability density distributions for the normalized current fluctuations (ΔI D) show only one Gaussian in wide-width devices, whereas they are separated into four Gaussians with increased in narrow-width devices. Therefore, fitting is performed through the carrier number fluctuation-correlated with mobility fluctuations model that separately considered the effects of sidewall. In narrow-width GAA SiNS FETs, consequently, the extracted interface trap densities (N T ) distribution becomes more dominant, and the scattering parameter ([Formula: see text]) distribution increases by more than double.

Real-time effect of electron beam on MoS2 field-effect transistors.

Irradiation of MoS2 field-effect transistors (FETs) fabricated on Si/SiO2 substrates with electron beams (e-beams) below 30 keV creates electron-hole pairs (EHP) in the SiO2, which increase the interface trap density (Nit ) and change the current path in the channel, resulting in performance changes. In situ measurements of the electrical characteristics of the FET performed using a nano-probe system mounted inside a scanning electron microscope show that e-beam irradiation enables both multilayer and monolayer MoS2 channels act as conductors. The e-beams mostly penetrate the channel owing to their large kinetic energy, while the EHPs formed in the SiO2 layer can contribute to the conductance by flowing into the MoS2 channel or inducing the gate bias effect. The analysis of the device parameters in the initial state and the vent-evacuation state after e-beam irradiation can clarify the effect of the interplay between the e-beam-induced EHPs and ambient adsorbates on the carrier behavior, which depends on the thickness of the MoS2 layer. DC and low frequency noise analysis reveals that the e-beam-induced EHPs increase Nit from 109-1010 to 1011 cm-2 eV-1 in both monolayer and multilayer devices, while the interfacial Coulomb scattering parameter αSC increases by three times in the monolayer and decreases to one-tenth of its original value in the multilayer. In other words, an MoS2 layer with a thickness of ∼30 nm is less sensitive to adsorbates by surface screening. Thus, the carrier mobility in the monolayer device decreases from 45.7 to 40 cm2 V-1 s-1, while in the 30 nm-thick multilayer device, it increases from 4.9 to 5.6 cm2 V-1 s-1. This is further evidenced by simulations of the distribution of interface traps and channel carriers in the MoS2 FET before and after e-beam irradiation, demonstrating that Coulomb scattering decreases as the effective channel moves away from the interface.

Upregulation of TRESK Channels Contributes to Motor and Sensory Recovery after Spinal Cord Injury.

TWIK (tandem-pore domain weak inward rectifying K+)-related spinal cord K+ channel (TRESK), a member of the two-pore domain K+ channel family, is abundantly expressed in dorsal root ganglion (DRG) neurons. It is well documented that TRESK expression is changed in several models of peripheral nerve injury, resulting in a shift in sensory neuron excitability. However, the role of TRESK in the model of spinal cord injury (SCI) has not been fully understood. This study investigates the role of TRESK in a thoracic spinal cord contusion model, and in transgenic mice overexpressed with the TRESK gene (TGTRESK). Immunostaining analysis showed that TRESK was expressed in the dorsal and ventral neurons of the spinal cord. The TRESK expression was increased by SCI in both dorsal and ventral neurons. TRESK mRNA expression was upregulated in the spinal cord and DRG isolated from the ninth thoracic (T9) spinal cord contusion rats. The expression was significantly upregulated in the spinal cord below the injury site at acute time points (6, 24, and 48 h) after SCI (p < 0.05). In addition, TRESK expression was markedly increased in DRGs below and adjacent to the injury site. TRESK was expressed in inflammatory cells. In addition, the number and fluorescence intensity of TRESK-positive neurons increased in the dorsal and ventral horns of the spinal cord after SCI. TGTRESK SCI mice showed faster paralysis recovery and higher mechanical threshold compared to wild-type (WT)-SCI mice. TGTRESK mice showed lower TNF-α concentrations in the blood than WT mice. In addition, IL-1ß concentration and apoptotic signals in the caudal spinal cord and DRG were significantly decreased in TGTRESK SCI mice compared to WT-SCI mice (p < 0.05). These results indicate that TRESK upregulated following SCI contributes to the recovery of paralysis and mechanical pain threshold by suppressing the excitability of motor and sensory neurons and inflammatory and apoptotic processes.

Axial Triangle of the Maxillary Sinus, and its Surgical Implication With the Position of Maxillary Sinus Septa During Sinus Floor Elevation: A CBCT Analysis.

The aim of this study was to measure the convexity of the lateral wall of the maxillary (Mx) sinus and identify the locational distribution of antral septa in relation to the zygomaticomaxillary buttress (ZMB), in order to suggest another anatomical consideration and surgical modification of sinus floor elevation procedures. This study was designed as a cross-sectional study, and a total of 134 patients and 161 sinuses containing edentulous alveolar ridges were analyzed. The angle between the anterior and lateral walls of the Mx sinus (lateral sinus angle [LSA]), and the angle between the midpalatal line and the anterior sinus wall (anterior sinus angle [ASA]) were measured. Mean LSAs and ASAs were 105.9° ± 9.86° and 58.4° ± 6.43°, respectively. No significant difference between left and right sides was found (LSA, P = .420; right = 105.5° ± 9.27°; left = 105.5° ± 9.27° and ASA, P = .564; right = 57.9° ± 6.80°; left = 58.8° ± 6.02°). The prevalence of septa was 37.3%, and it was most frequently noted in the second molar region (32.8%), followed by the first molar (20.9%), retromolar (16.4%), and second premolar regions (14.9%). Septa were most frequently located posterior to the ZMB (49.2%), while ZMB was mostly located in the first molar region (66.4%). Narrow LSAs may complicate the surgical approach to the posterior maxilla, especially when sinus elevation should be used in the second molar region. Considering the occasional presence of antral septa, membrane elevation may be complicated when a septum is encountered during the procedure. These results suggest that 3-dimensional examination of the convexity of the Mx sinus should be performed preoperatively to choose proper surgical techniques and minimize surgical complications.

Validation of a three-dimensional printed model for training of surgical extraction of supernumerary teeth.

INTRODUCTION: This study aimed to validate a three-dimensional (3D) printed model to provide training for supernumerary teeth (SNTs) extraction. MATERIALS AND METHODS: Each of the 30 participants, grouped as experienced and without experience, conducted two identically simulated surgeries on a 3D-printed replica of human mixed dentition with a SNT. The surgery time, area of bony window and volume of removed material were measured; subsequently, responses to a five-item questionnaire were recorded. The collected data were statistically analysed. RESULTS: The surgery time was 228.37 ± 141.53 seconds and 125.47 ± 53.03 seconds in the first and second surgery, respectively. The training significantly decreased the surgery time in the participants without experience (P = .000). However, there were no significant differences in the area of window opening (P = .271) and volume of removed material between the two surgeries (P = .075). The participants who perceived educational benefits accounted for more than 60% of the respondents for every question. Participants without experience in SNT extraction showed a tendency to rate a higher score than did those with experience. CONCLUSIONS: A 3D-printed model for surgical extraction of a SNT can improve surgical skill and, especially, shorten the learning curve in beginners.

The Effect of Polydeoxyribonucleotide Extracted from Salmon Sperm on the Restoration of Bisphosphonate-Related Osteonecrosis of the Jaw.

Bisphosphonates (BPs) used for treating skeletal diseases can induce bisphosphonate-related osteonecrosis of the jaw (BRONJ). Despite much effort, effective remedies are yet to be established. In the present study, we investigated the feasibility of polydeoxyribonucleotide (PDRN) extracted from salmon sperm for the treatment of BRONJ, in a BRONJ-induced rat model. Compared with BRONJ-induced samples, PDRN-treated samples exhibited lower necrotic bone percentages and increased numbers of blood vessels and attached osteoclast production. Moreover, local administration of PDRN at a high concentration (8 mg/kg) remarkably resolved the osteonecrosis. Findings from this study suggest that local administration of PDRN at a specific concentration may be considered clinically for the management of BRONJ.

Sequential Two-Stage Network and Thematic Analysis for Exploring an Interdisciplinary Care Approach in Nursing Homes.

Since various groups of older adults with different conditions and levels of function coexist in nursing homes, it is necessary to develop integrated care strategies through collaboration among experts across related fields. The purposes of this study are to identify the regularity of information sharing in managing daily function for older adults, with a special focus on interdisciplinary cooperation, and to explore a practical care strategy for nursing home residents. The collaborative methods of network and thematic analysis were done by conducting in-depth interviews with 33 interdisciplinary experts working at seven nursing homes. This study proposed three relationships and three themes as interrelated key factors for providing interdisciplinary care to the elderly at various levels of function based on the experiences accumulated by the practitioners. First, independent sharing is required to make professional judgments about how daily function in older adults changes from reported baselines. Second, practitioners accurately judge clinical situations and supplement experts' judgments through partial sharing. Finally, all interdisciplinary consensus through complete sharing achieves the ultimate goal of maintaining remaining function in older adults. These findings can be the first step in developing practical care guidelines for interdisciplinary use, and the results can be used to develop integrated assessment and intervention strategies.

Soft-type trap-induced degradation of MoS2 field effect transistors.

The practical applicability of electronic devices is largely determined by the reliability of field effect transistors (FETs), necessitating constant searches for new and better-performing semiconductors. We investigated the stress-induced degradation of MoS2 multilayer FETs, revealing a steady decrease of drain current by 56% from the initial value after 30 min. The drain current recovers to the initial state when the transistor is completely turned off, indicating the roles of soft-traps in the apparent degradation. The noise current power spectrum follows the model of carrier number fluctuation-correlated mobility fluctuation (CNF-CMF) regardless of stress time. However, the reduction of the drain current was well fitted to the increase of the trap density based on the CNF-CMF model, attributing the presence of the soft-type traps of dielectric oxides to the degradation of the MoS2 FETs.

Capacitance-voltage analysis of electrical properties for WSe2 field effect transistors with high-k encapsulation layer.

Doping effects in devices based on two-dimensional (2D) materials have been widely studied. However, detailed analysis and the mechanism of the doping effect caused by encapsulation layers has not been sufficiently explored. In this work, we present experimental studies on the n-doping effect in WSe2 field effect transistors (FETs) with a high-k encapsulation layer (Al2O3) grown by atomic layer deposition. In addition, we demonstrate the mechanism and origin of the doping effect. After encapsulation of the Al2O3 layer, the threshold voltage of the WSe2 FET negatively shifted with the increase of the on-current. The capacitance-voltage measurements of the metal insulator semiconductor (MIS) structure proved the presence of the positive fixed charges within the Al2O3 layer. The flat-band voltage of the MIS structure of Au/Al2O3/SiO2/Si was shifted toward the negative direction on account of the positive fixed charges in the Al2O3 layer. Our results clearly revealed that the fixed charges in the Al2O3 encapsulation layer modulated the Fermi energy level via the field effect. Moreover, these results possibly provide fundamental ideas and guidelines to design 2D materials FETs with high-performance and reliability.

Conductive multi-walled boron nitride nanotubes by catalytic etching using cobalt oxide.

Boron nitride nanotubes (BNNTs) are ceramic compounds which are hardly oxidized below 1000 °C due to their superior thermal stability. Also, they are electrically almost insulators with a large band gap of 5 eV. Thus, it is a challenging task to etch BNNTs at low temperature and to convert their electrical properties to a conductive behavior. In this study, we demonstrate that BNNTs can be easily etched at low temperature by catalytic oxidation, resulting in an electrically conductive behavior. For this, multi-walled BNNTs (MWBNNTs) impregnated with Co precursor (Co(NO3)2·6H2O) were simply heated at 350 °C under air atmosphere. As a result, diverse shapes of etched structures such as pits and thinned walls were created on the surface of MWBNNTs without losing the tubular structure. The original crystallinity was still kept in the etched MWBNNTs in spite of oxidation. In the electrical measurement, MWBNNTs with a large band gap were converted to electrical conductors after etching by catalytic oxidation. Theoretical calculations indicated that a new energy state in the gap and a Fermi level shift contributed to MWBNNTs being conductive.

Triethanolamine doped multilayer MoS2 field effect transistors.

Chemical doping has been investigated as an alternative method of conventional ion implantation for two-dimensional materials. We herein report chemically doped multilayer molybdenum disulfide (MoS2) field effect transistors (FETs) through n-type channel doping, wherein triethanolamine (TEOA) is used as an n-type dopant. As a result of the TEOA doping process, the electrical performances of multilayer MoS2 FETs were enhanced at room temperature. Extracted field effect mobility was estimated to be ∼30 cm2 V-1 s-1 after the surface doping process, which is 10 times higher than that of the pristine device. Subthreshold swing and contact resistance were also improved after the TEOA doping process. The enhancement of the subthreshold swing was demonstrated by using an independent FET model. Furthermore, we found that the doping level can be effectively controlled by the heat treatment method. These results demonstrate a promising material system that is easily controlled with high performance, while elucidating the underlying mechanism of improved electrical properties by the doping effect in a multilayered scheme.

Effects of sodium tri- and hexameta-phosphate in vitro osteoblastic differentiation in Periodontal Ligament and Osteoblasts, and in vivo bone regeneration.

The present study was designed to assess the effects and underlying mechanism of two poly(P) compounds, sodium triphosphate (STP, Na5P3O10) and sodium hexametaphosphate (SHMP, Na15P13O40~Na20P18O40) on osteoblastic differentiation of human periodontal ligament cells (PDLCs) and osteoblasts in vitro, and bone formation in vivo. Differentiation was assessed by alkaline phosphatase (ALP) activity, mineralization, and mRNA expression for marker genes. To examine the osteogenic potential to regenerate bone, the critical-sized mouse calvarial defect model was utilized. Incubation of PDLCs and osteoblasts with STP and SHMP resulted in a dose- and time-dependent increase in growth, alkaline phosphatase (ALP) activity, mineralization and mRNA expression for marker genes. STP and SHMP increased phosphorylation of adenosine monophosphate-activated protein kinase (AMPK), Akt, and mammalian target of rapamycin (mTOR), and mitogen-activated protein kinases (MAPK). Treatment with the mTOR inhibitor, rapamycin, attenuatted STP- and SHMP-induced osteoblastic differentiation. Micro-CT and histologic analysis showed that STP significantly increased new bone formation in calvarial defects, compared with SHMP and control group. Collectively, this is the first study to demonstrate that STP and SHMP promotes the osteoblastic differentiation in vitro, whereas STP only stimulated bone repair in vivo. Therefore, STP may be useful therapeutic approach for the regeneration of bone or periodontal tissue.

Sonic Hedgehog Promotes Cementoblastic Differentiation via Activating the BMP Pathways.

Although sonic hedgehog (SHH), an essential molecule in embryogenesis and organogenesis, stimulates proliferation of human periodontal ligament (PDL) stem cells, the effects of recombinant human SHH (rh-SHH) on osteoblastic differentiation are unclear. To reveal the role of SHH in periodontal regeneration, expression of SHH in mouse periodontal tissues and its effects on the osteoblastic/cementoblastic differentiation in human cementoblasts were investigated. SHH is immunolocalized to differentiating cementoblasts, PDL cells, and osteoblasts of the developing mouse periodontium. Addition of rh-SHH increased cell growth, ALP activity, and mineralization nodule formation, and upregulated mRNA expression of osteoblastic and cementoblastic markers. The osteoblastic/cementoblastic differentiation of rh-SHH was abolished by the SHH inhibitor cyclopamine (Cy) and the BMP antagonist noggin. rh-SHH increased the expression of BMP-2 and -4 mRNA, as well as levels of phosphorylated Akt, ERK, p38, and JNK, and of MAPK and NF-κB activation, which were reversed by noggin, Cy, and BMP-2 siRNA. Collectively, this study is the first to demonstrate that SHH can promote cell growth and cell osteoblastic/cementoblastic differentiation via BMP pathway. Thus, SHH plays important roles in the development of periodontal tissue, and might represent a new therapeutic target for periodontitis and periodontal regeneration.

Low frequency noise in single GaAsSb nanowires with self-induced compositional gradients.

Due to bandgap tunability, GaAsSb nanowires (NWs) have received a great deal of attention for a variety of optoelectronic device applications. However, electrical and optical properties of GaAsSb are strongly affected by Sb-related defects and scattering from surface states and/or defects, which can limit the performance of GaAsSb NW devices. Thus, in order to utilize the GaAsSb NWs for high performance electronic and optoelectronic devices, it is required to study the material and interface properties (e.g. the interface trap density) in the GaAsSb NW devices. Here, we investigate the low frequency noise in single GaAsSb NWs with self-induced compositional gradients. The current noise spectral density of the GaAsSb NW device showed a typical 1/f noise behavior. The Hooge's noise parameter and the interface trap density of the GaAsSb NW device were found to be ∼2.2 × 10(-2) and ∼2 × 10(12) eV(-1) cm(-2), respectively. By applying low frequency noise measurements, the noise equivalent power, a key figure of merit of photodetectors, was calculated. The observed low frequency noise properties can be useful as guidance for quality and reliability of GaAsSb NW based electronic devices, especially for photodetectors.

Schottky nanocontact of one-dimensional semiconductor nanostructures probed by using conductive atomic force microscopy.

To develop the advanced electronic devices, the surface/interface of each component must be carefully considered. Here, we investigate the electrical properties of metal-semiconductor nanoscale junction using conductive atomic force microscopy (C-AFM). Single-crystalline CdS, CdSe, and ZnO one-dimensional nanostructures are synthesized via chemical vapor transport, and individual nanobelts (or nanowires) are used to fabricate nanojunction electrodes. The current-voltage (I -V) curves are obtained by placing a C-AFM metal (PtIr) tip as a movable contact on the nanobelt (or nanowire), and often exhibit a resistive switching behavior that is rationalized by the Schottky (high resistance state) and ohmic (low resistance state) contacts between the metal and semiconductor. We obtain the Schottky barrier height and the ideality factor through fitting analysis of the I-V curves. The present nanojunction devices exhibit a lower Schottky barrier height and a higher ideality factor than those of the bulk materials, which is consistent with the findings of previous works on nanostructures. It is shown that C-AFM is a powerful tool for characterization of the Schottky contact of conducting channels between semiconductor nanostructures and metal electrodes.

Catalytic etching of monolayer graphene at low temperature via carbon oxidation.

In this work, an easy method to etch monolayer graphene is shown by catalytic oxidation in the presence of ZnO nanoparticles (NPs). The catalytic etching of monolayer graphene, which was transferred to the channel of field-effect transistors (FETs), was performed at low temperature by heating the FETs several times under an inert gas atmosphere (ZnO + C → Zn + CO or CO2). As the etching process proceeded, diverse etched structures in the shape of nano-channels and pits were observed under microscopic observation. To confirm the evolution of etching, current-voltage characteristics of monolayer graphene were measured after every step of etching by catalytic oxidation. As a result, the conductance of monolayer graphene decreased with the development of etched structures. This decrease in conductance was analyzed by percolation theory in a honeycomb structure. Finally, well-patterned graphene was obtained by oxidizing graphene under air in the presence of NPs, where Al was deposited on graphene as a mask for designed patterns. This method can substitute graphene etching via carbon hydrogenation using H2 at high temperature.

Volume stability of hydroxyapatite and ß-tricalcium phosphate biphasic bone graft material in maxillary sinus floor elevation: a radiographic study using 3D cone beam computed tomography.

OBJECTIVES: The purpose of this study was to confirm volume stability of biphasic calcium phosphate (BCP) through the changes of grafted volume over the time by 3D CT analyzing software program. PATIENTS AND METHODS: Fifteen patients, 16 sinuses who were scheduled a staged implantation through sinus floor elevation (SFE)-lateral window technique from 2009 to 2011 were included in the study. Of the 15 patients, eight were male and seven were female (mean age 50.1). For sinus floor augmentation, BCP with local blood was packed loosely into the maxillary sinus and the grafted site was covered with a collagen membrane. For the evaluation of volume change, 3D CBCT scans were taken five times at pre-operatively (To), post-op 1 week (T1), 1 month (T2), 3 months (T3), and 6 months (T4). 3D image processing software (OnDemand3DTM software) was used for this study. The time sequential change was statistically evaluated. RESULT: 84.32% grafted BCP is maintained until post-op 6 month (T4), and the average volume loss is 207.7 mm(3) (about 0.21 cc). Statistically, a significant volume change (decreasing) was observed in three groups (T2-T1, T3-T2, T4-T3). CONCLUSION: Biphasic calcium phosphate, as a synthetic material, has high volume stability and is a predictable graft material for the successful SFE. Although some limitations of the 3D analyzing software program, it is a fast, simple, relatively accurate and promising approach to quantifying long-term changes in the grafted area.

Three-dimensional evaluation of the pharyngeal airway using cone-beam computed tomography following bimaxillary orthognathic surgery in skeletal class III patients.

OBJECTIVE: The study aims to evaluate the pharyngeal airway space (PAS) following bimaxillary surgery in skeletal class III patients and to compare the changes in PAS between genders using cone-beam computed tomography (CBCT). MATERIALS AND METHODS: In all, 38 patients (16 male and 22 female) with skeletal class III malocclusion underwent bimaxillary surgery. CBCT scans were acquired approximately 1 month before surgery, 3 months after surgery, and 6 months after surgery. The oropharyngeal volume and the minimum cross-sectional area (CSA) were characterized using the InVivoDental imaging software package at each time point. RESULTS: The volume and minimum CSA decreased significantly postoperatively, which was maintained until 6 months postoperatively (p < 0.01). The location of the minimum CSA tended to move into the retropalatal and retroglossal areas postoperatively. A strong correlation between volume and minimum CSA was found. The amount of mandibular setback was not correlated with the change in the airway. By gender, significant decreases in both the volume and minimum CSA were found in females (p < 0.05) but not in males. CONCLUSION: Bimaxillary surgery significantly affects PAS. Gender differences should also be considered when considering changes in PAS. CLINICAL RELEVANCE: An awareness of the effects of bimaxillary setback surgery on the airway should be considered when implementing an orthognathic treatment plan.

The Influence of Cu Lattices on the Structure and Electrical Properties of Graphene Domains during Low-Pressure Chemical Vapor Deposition.

The influence of various Cu lattices on the texturing of graphene domains during low-pressure chemical vapor deposition was investigated in a large area. The results show that the sizes and shapes of graphene domains grown on Cu(111) substrates match well with those of the underlying Cu(111) domains, which seem to be quasi-single-crystalline. In contrast, on other Cu substrates such as (100) and more intermediate domains, graphene islands with poly-domains (ca. 85 %) are significantly nucleated, eventually merging into polycrystalline graphene. Within the overall channel-length range, graphene from a Cu foil shows a higher resistance compared to graphene from a Cu(111) domain, with the extracted average channel resistances being 34.51 Ω µm(-1) for Cu(111) and 66.17 Ω µm(-1) for the Cu foil.

Fabrication of controllable and stable In2O3 nanowire transistors using an octadecylphosphonic acid self-assembled monolayer.

The controllability and stability of nanowire transistor characteristics are essential for the development of low-noise and fast-switching nano-electronic devices. In this study, the positive shift of threshold voltage and the improvement of interface quality on In2O3 nanowire transistors were simultaneously achieved by using octadecylphosphonic acid (OD-PA) self-assembly. Following the chemical bond of OD-PA molecules on the surface of In2O3 nanowires, the threshold voltage was positively shifted to 2.95 V, and the noise amplitude decreased to approximately 87.5%. The results suggest that an OD-PA self-assembled monolayer can be used to manipulate and stabilize the transistor characteristics of nanowire-based memory and display devices that require high-sensitivity, low-noise, and fast-response.