Demonstration of a low power and high-speed graphene/silicon heterojunction near-infrared photodetector.

The structure and process of the graphene/Si heterojunction near-infrared photodetector were optimized to enhance the operating speed limit. The introduction of a well-designed structure improved the rise time from 12.6 µs to 115 ns, albeit at the expense of the responsivity, which decreased from 1.25 A W-1 to 0.56 A W-1. Similarly, the falling time was improved from 38 µs to 288 ns with a sacrifice in responsivity from 1.25 A W-1 to 0.29 A W-1, achieved through the introduction of Ge-induced defect-recombination centers within the well. Through a judicious well design and the introduction of recombination defect centers, the minimum pulse width could be improved from 50.6 µs to 435 ns, facilitating 2 MHz operation. This represents more than 100 times increase compared to previously reported graphene and graphene/Si hybrid photodetectors.

Changes in ocular biometrics following cycloplegic refraction in strabismic and amblyopic children.

This study was aimed to analyze ocular biometric changes following cycloplegia in pediatric patients with strabismus and amblyopia. Cycloplegia is routinely used to measure refractive error accurately by paralyzing accommodation. However, effects on axial length (AL), anterior chamber depth (ACD), keratometry (Km), and white-to-white distance (WTW) are not well studied in this population. This retrospective study examined 797 patients (1566 eyes) undergoing cycloplegic refraction at a Samsung Kangbuk hospital pediatric ophthalmology clinic from 2010 to 2023. Ocular biometry was measured before and after instilling 1% cyclopentolate and 0.5% phenylephrine/0.5% tropicamide. Patients were categorized by strabismus diagnosis, age, refractive error and amblyopia status. Differences in AL, ACD, Km, WTW, and refractive error pre- and post-cycloplegia were analyzed using paired t tests. ACD (3.44 ±â€…0.33 vs 3.58 ±â€…0.29 mm, P < .05) and WTW (12.09 ±â€…0.42 vs 12.30 ±â€…0.60 mm, P < .05) increased significantly after cycloplegia in all groups except other strabismus subgroup (Cs) in both parameters and youngest subgroup (G1) in ACD. Refractive error demonstrated a hyperopic shift from -0.48 ±â€…3.00 D to -0.06 ±â€…3.32 D (P < .05) in overall and a myopic shift from -6.97 ±â€…4.27 to -8.10 ±â€…2.26 in high myopia (HM). Also, AL and Km did not change significantly. In conclusion, cycloplegia impacts ocular biometrics in children with strabismus and amblyopia, significantly increasing ACD and WTW. Refractive error shifts hyperopically in esotropia subgroup (ET) and myopically in high myopia subgroup (HM), eldest subgroup (G3) relating more to anterior segment changes than AL/Km. Understanding cycloplegic effects on biometry is important for optimizing refractive correction in these patients.

Cecal duplication cyst in an infant presenting as shock: A case report.

BACKGROUND: Although intestinal obstruction is one of the most common surgical emergencies in an infant, it is difficult to diagnose neonatal enteric duplication cysts (EDC) preoperatively owing to their rarity as a cause of intestinal obstruction. We describe a case report of a neonatal EDC presenting intestinal obstruction and shock. CASE SUMMARY: A 32-d-old male infant with a prenatal sonographic finding of bladder distension was admitted to our hospital for a severely distended abdomen, fever, and oliguria. The first diagnostic hypothesis was septic shock and intestinal obstruction. The patient's symptoms worsened; following an emergency surgical exploratory laparotomy and histopathological findings, the final diagnosis of cecal duplication cyst was confirmed. The patient's postoperative course was uneventful, and on the fifth postoperative day, oral feeding restarted. Twenty days later, the patient was discharged from the hospital. CONCLUSION: Although EDC located in the cecum is exceptional, it should be considered when evaluating suspected intestinal obstruction and shock.

Numerical Optimization on Char Conversion and NOx Emission under Various Operating Conditions in a Retrofit Biomass Boiler.

Retrofitting retirement or existing fossil boiler with biomass is an important method of curbing electricity shortage and lowering the cost of modern power plants. However, the use of biomass combustion is hampered by operational problems, such as the resulting high unburned carbon, amount of bottom ash, and nitrogen oxide (NOx) release. In this study, we investigated the burning of pulverized biomass in a retrofitting boiler power plant using computational fluid dynamics of commercial software fluent ANSYS to determine the optimal combustion conditions. The objective of this study was to investigate a 125 MWe pulverized biomass boiler that was retrofitted from an anthracite down-fired boiler. The air distribution, including the influence of the secondary air ratio and the location of the burner standby, was evaluated. Key factors such as biomass ash mass at the hopper, char conversion, and high zone temperature relating to NOx formation/reduction were calculated. The adjustment of the secondary air ratio from 30 to 50% of the total air and the mass ash at the hopper significantly decreased to a low value at 247 kg/h and a high value of char conversion at 97.33% in case R (SA40%). The standard deviation temperature was 240 K at the BNR B-A level for case R, which was significantly lower than in other cases. This implies that the best mixing of air and biomass occurs in case R at 40%. Comparative analysis of the burner standby conditions showed that the NOx emission was similar at the boiler outlet (approximately 94-116 ppm). Burner A on standby, with a secondary air ratio of 40%, was used as the optimal case with the highest value of char conversion at 98.43%, the lowest bottom ash release of 204 kg/h, and a low-NOx emission of 106 ppm.

Demonstration of p-type stack-channel ternary logic device using scalable DNTT patterning process.

A p-type ternary logic device with a stack-channel structure is demonstrated using an organic p-type semiconductor, dinaphtho[2,3-b:2',3'-f]thieno[3,2-b]thiophene (DNTT). A photolithography-based patterning process is developed to fabricate scaled electronic devices with complex organic semiconductor channel structures. Two layers of thin DNTT with a separation layer are fabricated via the low-temperature deposition process, and for the first time, p-type ternary logic switching characteristics exhibiting zero differential conductance in the intermediate current state are demonstrated. The stability of the DNTT stack-channel ternary logic switch device is confirmed by implementing a resistive-load ternary logic inverter circuit.

Dual-channel P-type ternary DNTT-graphene barristor.

P-type ternary switch devices are crucial elements for the practical implementation of complementary ternary circuits. This report demonstrates a p-type ternary device showing three distinct electrical output states with controllable threshold voltage values using a dual-channel dinaphtho[2,3-b:2',3'-f]thieno[3,2-b]-thiophene-graphene barristor structure. To obtain transfer characteristics with distinctively separated ternary states, novel structures called contact-resistive and contact-doping layers were developed. The feasibility of a complementary standard ternary inverter design around 1 V was demonstrated using the experimentally calibrated ternary device model.

Glioblastoma-educated mesenchymal stem-like cells promote glioblastoma infiltration via extracellular matrix remodelling in the tumour microenvironment.

BACKGROUND: The biological function of mesenchymal stem-like cells (MSLCs), a type of stromal cells, in the regulation of the tumour microenvironment is unclear. Here, we investigated the molecular mechanisms underlying extracellular matrix (ECM) remodelling and crosstalk between MSLCs and glioblastomas (GBMs) in tumour progression. METHODS: In vitro and in vivo co-culture systems were used to analyze ECM remodelling and GBM infiltration. In addition, clinical databases, samples from patients with GBM and a xenografted mouse model of GBM were used. RESULTS: Previous studies have shown that the survival of patients with GBM from whom MSLCs could be isolated is substantially shorter than that of patients from whom MSLCs could not be isolated. Therefore, we determined the correlation between changes in ECM-related gene expression in MSLC-isolatable patients with that in MSLC non-isolatable patients using gene set enrichment analysis (GSEA). We found that lysyl oxidase (LOX) and COL1A1 expressions increased in MSLCs via GBM-derived clusters of differentiation 40 ligand (CD40L). Mechanistically, MSLCs are reprogrammed by the CD40L/CD40/NFκB2 signalling axis to build a tumour infiltrative microenvironment involving collagen crosslinking. Importantly, blocking of CD40L by a neutralizing antibody-suppressed LOX expression and ECM remodelling, decreasing GBM infiltration in mouse xenograft models. Clinically, high expression of CD40L, clusters of differentiation 40 (CD40) and LOX correlated with poor survival in patients with glioma. This indicated that GBM-educated MSLCs promote GBM infiltration via ECM remodelling in the tumour microenvironment. CONCLUSION: Our findings provide mechanistic insights into the pro-infiltrative tumour microenvironment produced by GBM-educated MSLCs and highlight a potential therapeutic target that can be used for suppressing GBM infiltration.

Demonstration of Anti-ambipolar Switch and Its Applications for Extremely Low Power Ternary Logic Circuits.

Anti-ambipolar switch (AAS) devices at a narrow bias region are necessary to solve the intrinsic leakage current problem of ternary logic circuits. In this study, an AAS device with a very high peak-to-valley ratio (∼106) and adjustable operating range characteristics was successfully demonstrated using a ZnO and dinaphtho[2,3-b:2',3'-f]thieno[3,2-b]thiophene heterojunction structure. The entire device integration was completed at a low thermal budget of less than 200 °C, which makes this AAS device compatible with monolithic 3D integration. A 1-trit ternary full adder designed with this AAS device exhibits excellent power-delay product performance (∼122 aJ) with extremely low power (∼0.15 µW, 7 times lower than the reference circuit) and lower device count than those of other ternary device candidates.

Effect of Blending Ratio and Temperature on CO2 Solubility in Blended Aqueous Solution of Monoethanolamine and 2-Amino-2-methyl-propanol: Experimental and Modeling Study Using the Electrolyte Nonrandom Two-Liquid Model.

This paper reports the newly measured experimental data for CO2 solubility in a blended aqueous solution of monoethanolamine (MEA) and 2-amino-2-methyl-propanol (AMP) at different amine mixing ratios (MEA/AMP/H2O = 9:21:70, 15:15:70, and 21:9:70 wt %) and working temperatures (323.15, 373.15, and 383.15 K). The successive substitution method was used for calculating the mole fractions of all molecules (four molecules) and electrolytes (three cations and four anions) from the equilibrium along with the material and charge balance equations (11 equations). The electrolyte nonrandom two-liquid (e-NRTL) model was used to investigate nonideality in the liquid phase. Using the abovementioned thermodynamic models, the partial pressures of CO2 in the gas phase, mole fractions of all components in the liquid phase, pH variations, heats of absorption, and cyclic capacities of CO2 according to the absorption/desorption temperature and the blending ratio of MEA/AMP were estimated.

Charging Effect by Fluorine-Treatment and Recess Gate for Enhancement-Mode on AlGaN/GaN High Electron Mobility Transistors.

An enhancement-mode AlGaN/GaN metal-insulator-semiconductor high-electron- mobility-transistor was fabricated using a recess gate and CF4 plasma treatment to investigate its reliable applicability to high-power devices and circuits. The fluorinated-gate device showed hysteresis during the DC current-voltage measurement, and the polarity and magnitude of hysteresis depend on the drain voltage. The hysteresis phenomenon is due to the electron trapping at the Al2O3/AlGaN interface and charging times longer than milliseconds were obtained by pulse I-V measurement. In addition, the subthreshold slope of the fluorinated-gate device was increased after the positive gate bias stress because of the two-dimensional electron gas reduction by ionized fluorine. Our systematic observation revealed that the effect of fluorine ions should be considered for the design of AlGaN/GaN power circuits.

Low-Temperature Oxidation Reactivity of Low-Rank Coals and Their Petrographic Properties.

Through the oxidation of coal at low temperatures and the resulting petrographic analysis, this study aims to predict spontaneous combustion, which has emerged as an industrial problem. Low-temperature oxidation analysis and the corresponding petrographic characteristics of four different coals treated under low temperatures of 25, 50, and 75 °C, which was set as the reactor temperature, were investigated. Low-temperature oxidation experiments designed at Pusan National University, based on papers related to low-temperature experiments, were conducted to analyze the constant of oxidation reactions. The petrographic characteristics of the coals were analyzed using a coal petrographic microscope spectrophotometer for determining their vitrinite reflectance and morphology, and the coals were extracted after the low-temperature oxidation experiments. After these analyses, vitrinite reflectance changed, and the normalized k, which is the difference between the constant of reaction from 25 °C to (the setting temperatures of) 50 and 75 °C, was also calculated. By comparing the oxidation rates of the coals and the corresponding petrographic analyses, the cause of spontaneous combustion can be deduced and a prediction can be made about which coal burns most efficiently at a low temperature.

Performance Degradation in Graphene-ZnO Barristors Due to Graphene Edge Contact.

The physical and chemical characteristics of the edge states of graphene have been studied extensively as they affect the electrical properties of graphene significantly. Likewise, the edge states of graphene in contact with semiconductors or transition-metal dichalcogenides (TMDs) are expected to have a strong influence on the electrical properties of the resulting Schottky junction devices. We found that the edge states of graphene form chemical bonds with the ZnO layer, which limits the modulation of the Fermi level at the graphene-semiconductor junction, in a manner similar to Fermi level pinning in silicon devices. Therefore, we propose that graphene-based Schottky contact should be accomplished with minimal edge contact to reduce the limits imposed on the Fermi level modulation; this hypothesis has been experimentally verified, and its microscopic mechanism is further theoretically examined.

Dynamic band alignment modulation of ultrathin WOx/ZnO stack for high on/off ratio field-effect switching applications.

A two-dimensional (2D) WOx/ZnO stack reveals a unique carrier transport behavior, which can be utilized as a novel device element to achieve a very high on/off ratio (>106) and an off current density lower than 1 nA cm-2. These unique behaviors are explained by a dynamic band alignment between WOx and ZnO, which can be actively modulated by a gate bias. The performance of FET utilizing the WOx/ZnO stack is comparable to those of other 2D heterojunction devices; however, it has a unique benefit in terms of process integration because of very low temperature process capability (T < 110 °C). The high on/off switching with extremely low off current density utilizing the dynamic band alignment modulation at the WOx/ZnO stack can be a very useful element for future device applications, especially in monolithic 3D integration or flexible electronics.

Effect of Temperature on the Mechanical Properties and Polymerization Kinetics of Polyamide-6 Composites.

This work reports the preparation of carbon fiber reinforced thermoplastic composites via the in situ anionic ring opening polymerization of ε-caprolactam. Vacuum assisted resin transfer molding was used to fabricate polyamide-6/carbon fiber composites at different molding temperatures. As a result, the higher polymerization of ε-caprolactam was observed with the condition at 140 °C for satisfactory impregnation. Regarding molding temperature, the physical properties of polyamide-6/carbon fiber were observed that the bending and impact strengths at 140 °C were higher than those to at other molding temperatures. The polymerization kinetics of polyamide-6 was analyzed using differential scanning calorimetry by experimentally acquiring kinetic parameters according to model fitting approaches. Polymerization and crystallization, which occur simultaneously throughout the whole process, were separated using Gaussian and Maxwell-Boltzmann distributions to study polymerization kinetics. The result of the developed model was in good agreement with the experimental data for the presented first order autocatalytic reaction model.

High-pressure oxygen annealing of Al2O3 passivation layer for performance enhancement of graphene field-effect transistors.

High-pressure annealing in oxygen ambient at low temperatures (∼300 °C) was effective in improving the performance of graphene field-effect transistors. The field-effect mobility was improved by 45% and 83% for holes and electrons, respectively. The improvement in the quality of Al2O3 and the reduction in oxygen-related charge generation at the Al2O3-graphene interface, are suggested as the reasons for this improvement. This process can be useful for the commercial implementation of graphene-based electronic devices.

A nationwide study of the incidence rate of herb-induced liver injury in Korea.

Discrepant incidence has been reported regarding the incidence of herb-induced liver injury (HILI). To address the growing worldwide concern of HILI, we evaluated the risk of HILI in a nationwide prospective study. Between April 2013 and January 2016, 1001 inpatients (360 males and 641 females) from 10 tertiary hospitals throughout South Korea were treated with herbal drugs and had their liver enzymes periodically measured. A total of six patients met the criteria for HILI with RUCAM scores ranging from 4 to 7. All these participants were women and developed the hepatocellular type of HILI. One HILI participant met the criteria for Hy's law; however, none of six cases presented clinical symptoms related to liver injury. This is the first nationwide prospective study that estimated the extent of the incidence of HILI [total: 0.60%, 95% confidence interval (CI) 0.12-1.08; women: 0.95%, 95% CI 0.19-1.68] and described its features in hospitalized participants.

Saeng-Kankunbi-Tang () protects liver against oxidative damage through activation of ERK/Nrf2 pathway.

OBJECTIVE: To investigate the cytoprotective effects of Saeng-kankunbi-tang (, SKT), a herbal prescription consisting of Artemisia capillaris and Alisma canaliculatum, and its underlying mechanism involved. METHODS: In mice, blood biochemistry and histopathology were assessed in carbon tetrachloride (CCl4)-induced oxidative hepatic injury in vivo. The animal groups included vehicle-treated control, CCl4, SKT 500 mg/(kg day) CCl4+SKT 200 or 500 mg/(kg day). In HepG2 cell, tert-butyl hydroperoxide (tBHP) induced severe oxidative stress and mitochondrial dysfunction in vitro. The cyto-protective effects of SKT were determined by 3-(4,5-dimethylthiazol)-2,5-diphenyltetrazolium bromide (MTT) assay, flfluorescence activated cell sorting analysis and western blotting. RESULTS: The administration of SKT prevented liver damage induced by CCl4 in mice, by inhibition of hepatocyte degeneration and inflflammatory cell infifiltration as well as plasma parameters such as alanine aminotransferase (P<0.01). Moreover, treatment with tBHP induced hepatocyte death and cellular reactive oxygen species production in hepatocyte cell line. However, SKT pretreatment (30-300 µg/mL) reduced this cell death and oxidative stress (P<0.01). More importantly, SKT inhibited the ability of tBHP to induce changes in mitochondrial membrane transition in cell stained with rhodamine 123 P<0.01). Furthermore, treatment with SKT induced extracellular signal-regulated kinases-mediated nuclear factor erythroid-2-related factor 2 (Nrf2) activation as well as the expressions of heme oxygenase 1 and glutamate- cystein ligase catalytic, Nrf2 target genes. CONCLUSIONS: SKT has the ability to protect hepatocyte against oxidative stress and mitochondrial damage mediated by Nrf2 activation.

Refractive predictability of partial coherence interferometry and factors that can affect it.

PURPOSE: To evaluate the refractive predictability of a partial coherence interferometry (PCI) biometry device (IOL Master) for cataract surgery and to investigate factors that may affect it. METHODS: Retrospective review of 209 eyes from 151 patients that had undergone preoperative PCI biometry and an uneventful phacoemulsification cataract surgery with posterior chamber intraocular lens (IOL) implantation was conducted. Prediction error defined as the intended refraction minus the postoperative refraction in spherical equivalent (SE) and the absolute error were analyzed according to IOL calculation formulas, patient characteristics, preoperative visual acuity (VA) and refraction, posterior subcapsular cataract (PSC), signal-to-noise ratio (SNR), and axial length (AL). RESULTS: The overall refractive predictability of the PCI device was good. Generally, the SRK/T formula performed better than the SRK-II formula. Refractive predictability was slightly worse in eyes with >or=+2.0 diopters (D) of preoperative SE (with both SRK-II and SRK/T) and in eyes with an ALor=+2.0D was related to a significantly greater hyperopic shift in postoperative refraction. With proper verification of measured data and a suitable IOL calculation formula, good refractive predictability is expected from PCI biometry regardless of patient characteristics, preoperative VA, SNR, PSC, and AL.

Clinical efficacy and complications of intraocular lens exchange for opacified intraocular lenses.

PURPOSE: To evaluate the clinical efficacy and complications of intraocular lens (IOL) exchange. METHODS: A review of medical records was performed for 52 eyes that had undergone an IOL exchange due to IOL opacification. Surgical complications and their incidences were analyzed. The mean best corrected visual acuity (BCVA) after the IOL exchange was compared with the mean pre-exchange BCVA and with the mean BCVA after the initial IOL implantation. Prediction error of refraction and biometric data obtained for the IOL exchange were, if available, compared with those obtained for the initial IOL implantation. The prediction error for the IOL exchange, calculated from the biometric data obtained before the IOL exchange, was compared with that calculated from the measurements obtained before the initial IOL implantation. RESULTS: The overall complication rates were low and no serious complications were found. The mean BCVA improved significantly after the IOL exchange and was not significantly different from that obtained after the initial IOL implantation. However, the refractive prediction for the IOL exchange was not as good as it was for the initial IOL implantation, which was thought to be related with difficulties in axial length (AL) measurements. Biometric data taken before the initial IOL implantation was associated with a significantly better refractive prediction than those taken before the IOL exchange. CONCLUSIONS: IOL exchange was both efficacious and safe for visual recovery. However, IOL exchange was related with increased difficulty of predicting postoperative refraction; difficulties in AL measurements are the suggested cause.