Advanced Atomic Layer Deposition: Ultrathin and Continuous Metal Thin Film Growth and Work Function Control Using the Discrete Feeding Method.

The ultrathin and continuous ruthenium (Ru) film was deposited through an improved atomic layer deposition (ALD) process with a discrete feeding method (DFM), called DF-ALD, employing a cut-in purge step during the precursor feeding. The excess precursor molecules can be physically adsorbed onto the chemisorbed precursors on the substrate during precursor feeding, which screens the reactive sites on the surface. Using DF-ALD, surface coverage of precursors was enhanced because the cut-in purge removes the physisorbed precursors securing the reactive sites beneath them; thus, nucleation density was greatly increased. Therefore, the grain size decreased, which changed the microstructure and increased oxygen impurity concentration. However, a more metallic Ru thin film was formed due to thermodynamic stability and improved physical density. Consequently, DF-ALD enables the deposition of the ultrathin (3 nm) and continuous Ru film with a low resistivity of ∼60 µΩ cm and a high effective work function of ∼4.8 eV.

Two-Dimensional Stacked Composites of Self-Assembled Alkane Layers and Graphene for Transparent Gas Barrier Films with Low Permeability.

Self-assembled alkane layers are introduced between graphene layers to physically block nanometer size defects in graphene and lateral gas pathways between graphene layers. A well-defined hexatriacontane (HTC) monolayer on graphene could cover nanometer-size defects because of the flexible nature and strong intermolecular van der Waals interactions of alkane, despite the roughness of graphene. In addition, HTC multilayers between graphene layers greatly improve their adhesion. This indicates that HTC multilayers between graphene layers can effectively block the lateral pathway between graphene layers by filling open space with close-packed self-assembled alkanes. By these mechanisms, alternately stacked composites of graphene and self-assembled alkane layers greatly increase the gas-barrier property to a water vapor transmission rate (WVTR) as low as 1.2 × 10-3 g/(m2 day), whereas stacked graphene layers generally show a WVTR < 0.5 g/(m2 day). Furthermore, the self-assembled alkane layers have superior crystallinity and wide bandgap, so they have little effect on the transmittance.

Guided Lateral Window Osteotomy Using Dynamic Navigation for Maxillary Sinus Augmentation: A Novel Technique.

The size and the position of the sinus antrostomy play a key role in making sinus grafting surgery more predictable and effective with less complications. A cone beam computed tomography and intraoral scan of the maxilla were taken for a patient who is missing maxillary first molar tooth with limited residual bone. Data were exported to the dynamic navigation (DN) system software. Sinus lateral window osteotomy position and dimensions were determined and planned using four 1.5 mm diameter implants placed on the maxillary sinus lateral wall. The osteotomy was initiated following the planned four 1.5 mm implants in a parallel motion to the bone surface using dynamic navigation guidance; thus, creating an outline for the lateral sinus window. Afterword's, the lateral sinus window was greenstick fractured and the membrane was lifted; first molar implant osteotomy done, implant placed, and bone graft material was placed. The flap was sutured, and post-operative instructions and medications were given. No post-operative complications noticed. The outline of the lateral window osteotomy along with implant osteotomy can be accurately planned and executed using DN technology, which may potentially reduce complications and insure accurate placement of the implant and the graft.

Discrepancies in periodontitis classification among dental practitioners with different educational backgrounds.

BACKGROUND: The 2018 classification of periodontal disease characterizes the disease with a multidimensional staging and grading system. The purpose of this multicenter study was to examine variations in periodontitis classification among dental practitioners with different postgraduate educational backgrounds at the University of Maryland School of Dentistry and the Loma Linda University School of Dentistry using the 2018 classification. METHODS: This cross-sectional observational study included two cohorts: dental practitioners with periodontal backgrounds (n1 = 31) and those with other educational backgrounds (n2 = 33). The survey instrument contained three periodontitis cases presented with the guideline of the 2018 classification and a questionnaire including closed and open-ended questions. The participants were asked to review each case and to fill out the questionnaire independently. Fisher's exact test was conducted to examine the differences in responses between the two cohorts. Polychoric correlations were calculated to examine the relation between the level of familiarity with the 2018 classification and the accuracy of the classification. RESULTS: The distribution of item responses was significantly different between the two cohorts regarding only one item, grading for Case 1 (p = 0.01). No significant differences in accuracy between the two cohorts were observed except for two items, grading in Case 1 (p = 0.03) and staging in Case 3 (p = 0.04). There were no significant differences in risk factor identification for each case among the two cohorts (p = 1.00, Case 1; p = 0.22, Case 2). Staging in Case 3 ([Formula: see text] = 0.52) and risk factor identification in Case 2 ([Formula: see text]= 0.32) were significantly correlated with familiarity with the 2018 classification. CONCLUSION: A fair level of agreement in periodontitis classification was observed among dental practitioners with different educational backgrounds when the 2018 classification was used. The periodontal cohort showed better agreement levels and partially better accuracy. Risk factor identification for periodontal disease was difficult regardless of the educational background.

Results of Intradermal Skin Testing with Cefazolin according to a History of Hypersensitivity to Antibiotics.

BACKGROUND: The relationship between cephalosporin hypersensitivity and a history of ß-lactam hypersensitivity is unclear. We evaluated the usefulness of routine intradermal cefazolin skin testing and its relationship with the history of ß-lactam hypersensitivity. METHODS: The electronic medical records of patients who underwent intradermal cefazolin (0.3 mg/mL) skin testing without negative controls from January 2010 to January 2011 at Seoul National University Bundang Hospital were evaluated. The history of ß-lactam hypersensitivity of the patients was taken. Immediate adverse reactions after cefazolin injection were evaluated by searching the electronic medical records for key words and reviewing consultation documents of allergy specialists or dermatologists. The medical records of the patients were reviewed by an allergist. RESULTS: There were 13,153 cases of cefazolin skin testing over the 13-month study period. Among the 12,969 cases with negative skin test results, 8 had immediate hypersensitivity related to cefazolin (0.06%). The negative predictive value of cefazolin skin testing alone was 99.94%. The overall positivity rate of cefazolin skin tests was 1.4% (184/13,153). Of the cases with a history of allergy to ß-lactams, 15% (6/40) showed a positive cefazolin skin test result compared to only 1.36% (178/13,113) of cases with no such history (P < 0.001) including some false-positive tests. CONCLUSION: The results suggest that routine screening involving cefazolin skin testing without negative controls is not useful for all patients, but could be helpful for those with a history of ß-lactam hypersensitivity, although a large prospective study is needed to confirm this.

Contact Mechanics of Anatomic Radial Head Prosthesis: Comparison Between Native Radial Head and Anatomic Radial Head Prostheses in the Dynamic Mode.

PURPOSE: The biomechanical characteristics of anatomic radial head prostheses have not been completely investigated. We compared and analyzed the contact kinematic characteristics of the native radial head and radial head prostheses replicating the native head contour, using a real-time flexion simulation model. METHODS: Ten fresh-frozen cadavers were used in this pilot study. A simulating dynamic motion mode from 0° to 130° of elbow flexion was applied. Radiocapitellar contact pressure and area were measured using a real-time digitized pressure sensor. Further, contact area and pressure curves were obtained during flexion, using a motion-tracking device. RESULTS: The mean contact area, mean contact pressure, and peak contact pressure of the native radial head and radial head prosthesis were 39 mm2, 0.0078 kgf/mm2, 0.0123 kgf/mm2, and 33 mm2, 0.0093 kgf/dm2, 0.0148 kgf/mm2, respectively. The contact area and pressure curves were parabolic nonlinear for the radial head prosthesis and more linear for the native radial head. CONCLUSIONS: The radial head prosthesis mimics the mechanics of the native radial head in terms of mean contact area, mean contact pressure, and peak contact pressure; however, different patterns of contact pressure and area curves during elbow flexion-extension were observed. CLINICAL RELEVANCE: We found that the biomechanics of the anatomic radial head prostheses used in the study were similar to those of the native radial head.

Unbiased compound screening with a reporter gene assay highlights the role of p13 in the cardiac cellular stress response.

We recently showed that a 13-kDa protein (p13), the homolog protein of formation of mitochondrial complex V assembly factor 1 in yeast, acts as a potential protective factor in pancreatic islets under diabetes. Here, we aimed to identify known compounds regulating p13 mRNA expression to obtain therapeutic insight into the cellular stress response. A luciferase reporter system was developed using the putative promoter region of the human p13 gene. Overexpression of peroxisome proliferator-activated receptor gamma coactivator 1α, a master player regulating mitochondrial metabolism, increased both reporter activity and p13 expression. Following unbiased screening with 2320 known compounds in HeLa cells, 12 pharmacological agents (including 8 cardiotonics and 2 anthracyclines) that elicited >2-fold changes in p13 mRNA expression were identified. Among them, four cardiac glycosides decreased p13 expression and concomitantly elevated cellular oxidative stress. Additional database analyses showed highest p13 expression in heart, with typically decreased expression in cardiac disease. Accordingly, our results illustrate the usefulness of unbiased compound screening as a method for identifying novel functional roles of unfamiliar genes. Our findings also highlight the importance of p13 in the cellular stress response in heart.

Digital data acquisition of shoulder range of motion and arm motion smoothness using Kinect v2.

BACKGROUND: Range of motion (ROM) is a clinically important parameter in evaluating joint function. However, dynamic evaluation to determine the quality of the arm motion using digitized measurement is often overlooked during clinical assessment. We evaluated the accuracy of Kinect v2 (Microsoft, Redmond, WA, USA) as a digital tool for measuring shoulder ROM objectively and proposed a concept of motion smoothness reflecting the quality of arm motion. METHODS: Ten male participants were included in a 2-stage experiment. First, shoulder ROM was measured in 4 static poses (flexion, abduction, external rotation, and internal rotation) with Kinect v2, a 3-dimensional (3D) motion analysis system, and goniometry. Second, participants performed a point-to-point arm motion as naturally as possible. Kinematic data were collected with Kinect v2 and the 3D motion analysis system and then postprocessed to acquire parameters related to motion smoothness, including peak to mean velocity ratio, acceleration to movement time ratio, and number of peaks. RESULTS: Kinect v2 resulted in very good agreement of ROM measurement (r > 0.9) with the 3D motion analysis (95% limits of agreement < ±8°) compared with goniometry (95% limits of agreement < ±10°). Kinect v2 also showed a good correlation and agreement of measurement of motion quality parameters compared with the 3D motion analysis (peak to mean velocity ratio, acceleration to movement time ratio, and number of peaks: r = 0.769, discrepancy = ±0.1; r = 0.922, discrepancy = ±5%; and mean = 1 ± 0, respectively). CONCLUSIONS: We show that Kinect v2 can be used as a reliable tool to measure shoulder ROM and arm motion smoothness.

The relationship between cognitive performance and insulin resistance in non-diabetic patients with mild cognitive impairment.

OBJECTIVE: Insulin resistance (IR) is a distinct and early feature of type 2 diabetes mellitus and metabolic syndrome. IR is thought to play a vital role in cognitive impairment. We conducted this study to understand the early characteristics of cognitive dysfunctions attributable to IR. METHODS: This study included 85 consecutive non-diabetic elderly participants with mild cognitive impairment (MCI). IR was estimated with the homeostasis model assessment of insulin resistance (HOMA-IR). Cognitive performances were analyzed as a function of scores on the HOMA-IR. RESULTS: The group analysis those with and without IR did not show any differences in the cognitive performance although higher HOMA-IR was closely associated with lower performances in immediate recall on the Seoul Verbal Learning Test (SVLT-I) (r = -0.244, p = 0.026) and Controlled Oral Word Association Test (COWAT) (r = -0.270, p = 0.013). In subgroup analysis by APOE status, SVLT-delayed (p = 0.027) and COWAT (p = 0.016) scores were found to be significantly lower in the IR than the non-IR among those with APOE ε4 allele. In multiple regression analysis, impairment on the COWAT remained significantly correlated with scores on HOMA-IR (ß = -0.271, t = -2.340, p = 0.022). However, IR status was identified to interact with APOE ε4 carriership toward poor performances in the COWAT (ß = -0.335, t = -2.285, p = 0.026). CONCLUSION: This study found a domain-specific impact of HOMA-IR scores on cognitive performances in non-diabetic patients with MCI. This association was profound only in APOE ε4carriers.

Sasang constitution affects the prevalence of functional dyspepsia.

BACKGROUND: Functional dyspepsia (FD), which is a very common disorder worldwide, is known to be caused by multiple factors including environmental and genetic factors. Sasang constitutional medicine (SCM) is a component of traditional Korean medicine that emphasizes inherited characteristics of the physical and psychological patterns of a patient. This study investigated whether the prevalence of FD differs depending on Sasang classification. METHODS: A total 517 subjects (190 males and 327 females) were recruited, and interviewed for the presence of FD using a Rome III-based questionnaire. The Sasang constitution of all subjects were diagnosed using a Sasang constitutional analytical tool (SCAT). A Chi-square test was performed to compare prevalence of DF among different Sasang constitutional types. RESULTS: Of the 517 subjects, 115 (22.2 %) met the diagnostic criteria for FD, and the prevalence was significantly higher in females (26.9 %) than males (14.2 %, p < 0.01). The Sasang-constitution-based prevalence among all subjects was 27.5 % for Taeumin, 23.1 % for Soumin, and 16.4 % for Soyangin (p = 0.055). When compared by sex, the prevalence of FD among Sasang types showed significantly different patterns between males and females (p < 0.05); in females with FD, Taeumin predominated (32.5 % compared with 29.5 % and 18.8 % for Soumin and Soyangin, respectively; p < 0.05), whereas males with FD displayed a higher prevalence of Soumin (17.3 % compared with 9.1 % and 11.3 % for Taeumin and Soyangin, respectively; p > 0.05). CONCLUSIONS: This study identified significant differences in FD prevalence depending on Sasang constitution and sex. Our findings provide data to guide future research on the prevention and management of FD.

Genome-wide methylation profiling of the bronchial mucosa of asthmatics: relationship to atopy.

BACKGROUND: Asthma is a common respiratory disease that is characterized by bronchial hyperresponsiveness and airway obstruction due to chronic airway inflammation. Atopic asthma is a typical IgE-mediated disease in which the enhanced production of IgE is driven by the activation of Th2 cells, which release a distinct pattern of cytokines, including interleukin 4 (IL4) and IL3, in response to specific antigen presentation. To evaluate the methylation status of the whole genomes of bronchial mucosa tissues from subjects who lacked or had sensitization to Dermatophagoides farina (Df) and Dermatophagoides pteronyssinus (Dp). METHODS: The genome-wide DNA methylation levels in the bronchial mucosa tissues of atopic asthmatics (N=10), non-atopic asthmatics (N=7), and normal controls (N=7) were examined using microarrays. RESULTS: In the bronchial mucosa of atopic asthmatics, hypermethylation was detected at 6 loci in 6 genes, while hypomethylation was detected at 49 loci in 48 genes compared to those of non-atopic asthmatics. Genes that were assigned the ontologies of multicellular organismal process, response to organic substance, hormone metabolic process, and growth factor receptor binding were hypomethylated. The methylation levels in the mucosa of asthmatics and normal controls were similar. CONCLUSIONS: The bronchial mucosa of asthmatics who are atopic to Df or Dp have characteristic methylation patterns for 52 genes. The genes and pathways identified in the present study may be associated with the presence of atopy in asthmatics and therefore represent attractive targets for future research.

Selective Blocking of Graphene Defects Using Polyvinyl Alcohol through Hydrophilicity Difference.

Defects on graphene over a micrometer in size were selectively blocked using polyvinyl alcohol through the formation of hydrogen bonding with defects. Because this hydrophilic PVA does not prefer to be located on the hydrophobic graphene surface, PVA selectively filled hydrophilic defects on graphene after the process of deposition through the solution. The mechanism of the selective deposition via hydrophilic-hydrophilic interactions was also supported by scanning tunneling microscopy and atomic force microscopy analysis of selective deposition of hydrophobic alkanes on hydrophobic graphene surface and observation of PVA initial growth at defect edges.

Asp664 cleavage of amyloid precursor protein induces tau phosphorylation by decreasing protein phosphatase 2A activity.

Caspase cleavage of amyloid precursor protein (APP) has been reported to be important in amyloid beta protein (Aß)-mediated neurotoxicity. However, the underlying mechanisms are not clearly understood. In this study, we explored the effect of caspase cleavage of APP on tau phosphorylation in relation to Aß. We found that Asp664 cleavage of APP increased tau phosphorylation at Thr212 and Ser262 in N2A cells and primary cultured hippocampal neurons. Compared with wild-type APP, protein phosphatase 2A (PP2A) activity was significantly increased when Asp664 cleavage was blocked by the D664A point mutation. Furthermore, we found that over-expression of C31 reduced PP2A activity. C31 binds directly to the PP2A catalytic subunit, through the asparagine, proline, threonine, tyrosine (NPTY) motif, which is essential for C31-induced tau hyperphosphorylation. However, it appears that the other fragment produced by Asp664 cleavage, Jcasp, modulates neither PP2A activity nor tau hyperphosphorylation. Asp664 cleavage and accompanying tau hyperphosphorylation were remarkably diminished by blockage of Aß production using a γ-secretase inhibitor. Taken together, our results suggest that Asp664 cleavage of APP leads to tau hyperphosphorylation at specific epitopes by modulating PP2A activity as a downstream of Aß. Direct binding of C31 to PP2A through the C31-NPTY domain was identified as a mechanism underlying this effect.

Differential gene expression profile in PBMCs from subjects with AERD and ATA: a gene marker for AERD.

Aspirin-exacerbated respiratory disease (AERD) is associated with severe asthma and aspirin can cause asthma to worsen, often in the form of a severe and sudden attack. The oral aspirin challenge is the gold standard to confirm the diagnosis of AERD, but it is time consuming and produces serious complications in some cases. Therefore, more efficient and practical method is needed to predict AERD patients. The aim of the present study was to identify AERD-related gene expression in peripheral blood mononuclear cells (PBMCs) and examine the diagnostic potential of these candidate gene(s) for predicting AERD. To do this, RNAs from 24 subjects with AERD and 18 subjects with aspirin-tolerant asthma (ATA) were subjected to microarray analysis of ~34,560 genes. In total, 10 genes were selected as candidate gene markers by applying p ≤ 0.001(t test) and ≥8-fold change, and to correct for multiple comparisons, the false discovery rate analyses were performed. By applying multiple logistic regression analysis, among possible 1,023 models (2(10)-1), a model consisting of CNKSR3, SPTBN2, and IMPACT was selected as candidate set, because this set showed the best AUC (0.98) with 88 % sensitivity and 89 % specificity. For validation, mRNA levels by real-time PCR on PBMCs from two population sets in a gene-chip study and another replication sample, 20 AERD, 20 ATA, and 8 normal controls, were significantly different between groups with 100 % sensitivity and 100 % specificity in each of the two population sets. However, IMPACT gene did not differentiate between AERD and normal controls. The set of the two genes (CNKSR3 and SPTBN2) showed the best AUC (0.96) with 88 % sensitivity and 94 % specificity in a gene-chip study sample. In addition, this set showed perfect discriminative power with AUC (1.0, 100 % sensitivity and 100 % specificity) in each of the two population sets: the gene-chip samples and the replication samples. It also showed perfect discrimination for AERD from NC (AUC: 1.0) and ATA from NC (AUC: 1.0). In conclusion, we developed the two gene markers (CNKSR3 and SPTBN2) of PBMC which differentiate between AERD and ATA with a perfect discriminative power. These gene markers may be an efficient and practical method for predicting AERD.

Milk Protein-Derived Antioxidant Tetrapeptides as Potential Hypopigmenting Agents.

Excessive accumulation of melanin can cause skin pigmentation disorders, which may be accompanied by significant psychological stress. Although many natural and synthetic products have been developed for the regulation of melanogenesis biochemistry, the management of unwanted skin pigmentation remains challenging. Herein, we investigated the potential hypopigmenting properties of peptide sequences that originated from milk proteins such as ĸ-casein and ß-lactoglobulin. These proteins are known to inhibit melanogenesis and their hydrolysates are reported as antioxidant peptides. We synthesize tetrapeptide fragments of the milk protein hydrolysates and investigate the amino acids that are essential for designing peptides with tyrosinase inhibitory and antioxidant activities. We found that the peptide methionine-histidine-isoleucine-arginine amide sufficiently inhibits mushroom tyrosinase activity, shows potent antioxidant activity and effectively impedes melanogenesis in cultured melanocytes via cooperative biological activities. Our findings demonstrate the potential utility of the bioactive tetrapeptide from milk proteins as a chemical alternative to hypopigmenting agents.

A Behavior-Learned Cross-Reactive Sensor Matrix for Intelligent Skin Perception.

Mimicking human skin sensation such as spontaneous multimodal perception and identification/discrimination of intermixed stimuli is severely hindered by the difficulty of efficient integration of complex cutaneous receptor-emulating circuitry and the lack of an appropriate protocol to discern the intermixed signals. Here, a highly stretchable cross-reactive sensor matrix is demonstrated, which can detect, classify, and discriminate various intermixed tactile and thermal stimuli using a machine-learning approach. Particularly, the multimodal perception ability is achieved by utilizing a learning algorithm based on the bag-of-words (BoW) model, where, by learning and recognizing the stimulus-dependent 2D output image patterns, the discrimination of each stimulus in various multimodal stimuli environments is possible. In addition, the single sensor device integrated in the cross-reactive sensor matrix exhibits multimodal detection of strain, flexion, pressure, and temperature. It is hoped that his proof-of-concept device with machine-learning-based approach will provide a versatile route to simplify the electronic skin systems with reduced architecture complexity and adaptability to various environments beyond the limitation of conventional "lock and key" approaches.

Long-term survival of a child with homozygous protein C deficiency successfully treated with living donor liver transplantation.

Homozygous protein C deficiency is an autosomal recessive disorder often presenting with purpura fulminans. Fresh frozen plasma and oral anticoagulation have been used in the treatment of this disease. Lately, protein C concentrate has become the treatment of choice. However, protein C concentrate is not yet widely available in many countries. We report a six-month-old girl with homozygous protein C deficiency who had suffered from frequent thrombotic episodes. She was successfully treated with living donor liver transplantation. Eight years after the transplantation, she remains symptom free. As described here, the liver transplantation offers an alternative curative treatment for children with homozygous protein C deficiency.

Accuracy of Implants Placed with Surgical Guides: Thermoplastic Versus 3D Printed.

This study was conducted to evaluate the accuracy of implants placed using two different guided implant surgery materials: thermoplastic versus three-dimensionally (3D) printed. A cone beam computed tomography (CBCT) scan previously obtained and selected for single-tooth implant replacement was converted into a Digital Imaging and Communications in Medicine (DICOM) file. All models were planned and exported for printing using BlueSkyBio Plan Software with the DICOM files. A total of 20 3D-printed mandibular quadrant jaws replicating the CBCT were printed by Right Choice Milling, as was the control model to accept the control implant. Previously, 10 thermoplastic and 10 3D-printed surgical guides had been made by the same lab technician at Right Choice Milling. One Nobel Biocare implant with a trilobe connection was placed per guide and replica jaw model pair. Implants were placed using the thermoplastic and 3D-printed surgical guides, representing the two test groups, following the Nobel Biocare guided surgical protocol. A total of 21 CBCT scans were then taken, one for the control implant and one for each test implant. The CBCT volume was converted to a DICOM file and transferred to Invivo5 software version 5.4 (Anatomage). The DICOM file of each test implant was superimposed over the DICOM file of the control. The deviation of the head of the implant, the deviation of the apex of the implant, and the angle of deviation were evaluated from measurements on the superimposition of the control and test implants. Mann-Whitney U test was used to test the null hypotheses at α = .05 and a confidence interval of 95%. Descriptive statistics were used for the average ± standard deviation. The implants placed with the thermoplastic surgical guides showed an average of 3.40 degrees of angular deviation compared to 2.36 degrees for implants placed with the 3D-printed surgical guides (P = .143). The implants placed with the thermoplastic surgical guides showed an average of 1.33 mm of deviation at the head of the implant compared to 0.51 mm for implants placed with the 3D-printed surgical guides (P < 0.001). The implants placed with the thermoplastic surgical guides showed an average of 1.6 mm of deviation at the apex of the implant compared to 0.76 mm for implants placed with the 3D-printed surgical guides (P < .001). There was no significant difference in the angular deviations of implants placed with thermoplastic surgical guides compared to those placed with the 3D-printed surgical guide. However, the locations of the implant head and implant apex were significantly more accurate for the implants placed with the 3D-printed surgical guides compared to those placed with the thermoplastic surgical guides.

Stable Logic Operation of Fiber-Based Single-Walled Carbon Nanotube Transistor Circuits Toward Thread-Like CMOS Circuitry.

A fiber-based single-walled carbon nanotube (SWCNT) thin-film-transistor (TFT) has been proposed. We designed complementary SWCNT TFT circuit based on SPICE simulations, with device parameters extracted from the fabricated fiber-based SWCNT TFTs, such as threshold voltage, contact resistance, and off-/gate-leakage current. We fabricated the SWCNTs CMOS inverter circuits using the selective passivation and n-doping processes on a fiber substrate. By comparing the simulation and experimental results, we could enhance the circuit's performance by tuning the threshold voltage between p-type and n-type TFTs, reducing the source/drain contact resistance and off current level, and maintaining a low output capacitance of the TFTs. Importantly, it was found that the voltage gain, output swing range, and frequency response of the fiber-based inverter circuits can be dramatically improved.

Corrugated Heterojunction Metal-Oxide Thin-Film Transistors with High Electron Mobility via Vertical Interface Manipulation.

A new strategy is reported to achieve high-mobility, low-off-current, and operationally stable solution-processable metal-oxide thin-film transistors (TFTs) using a corrugated heterojunction channel structure. The corrugated heterojunction channel, having alternating thin-indium-tin-zinc-oxide (ITZO)/indium-gallium-zinc-oxide (IGZO) and thick-ITZO/IGZO film regions, enables the accumulated electron concentration to be tuned in the TFT off- and on-states via charge modulation at the vertical regions of the heterojunction. The ITZO/IGZO TFTs with optimized corrugated structure exhibit a maximum field-effect mobility >50 cm2 V-1 s-1 with an on/off current ratio of >108 and good operational stability (threshold voltage shift <1 V for a positive-gate-bias stress of 10 ks, without passivation). To exploit the underlying conduction mechanism of the corrugated heterojunction TFTs, a physical model is implemented by using a variety of chemical, structural, and electrical characterization tools and Technology Computer-Aided Design simulations. The physical model reveals that efficient charge manipulation is possible via the corrugated structure, by inducing an extremely high carrier concentration at the nanoscale vertical channel regions, enabling low off-currents and high on-currents depending on the applied gate bias.