Tailored fabrication of a self-rolled-up AlGaN/GaN tubular structure with photoelectrochemical etching

Group III-nitride semiconductors with tubular structures offer significant potential across various applications, including optics, electronics, and chemical sensors. However, achieving tailored fabrication of these structures remains a challenge. In this study, we present a novel, to the best of our knowledge, method to fabricate micro-sized tubular structures by rolling the layered membrane of group III-nitride alloys utilizing the photoelectrochemical (PEC) etching. To customize the geometry of the tubular structure, we conducted an analytic calculation to predict the strain and deformation for the layered membrane. Based on the calculations, we designed and fabricated an AlGaN/GaN/InGaN/n-GaN/ sapphire structure using metal-organic chemical vapor deposition (MOCVD). Photolithography and PEC etching were employed to selectively etch the sacrificial InGaN layer. We investigated the changes of optical properties of the rolled-up structure by utilizing micro-photoluminescence (µ-PL) and micro-Raman spectroscopy.

Electrically Confined Electroluminescence of Neutral Excitons in WSe2 Light-Emitting Transistors

Monolayer transition metal dichalcogenides (TMDs) have drawn significant attention for their potential in optoelectronic applications due to their direct band gap and exceptional quantum yield. However, TMD-based light-emitting devices have shown low external quantum efficiencies as imbalanced free carrier injection often leads to the formation of non-radiative charged excitons, limiting practical applications. Here, electrically confined electroluminescence (EL) of neutral excitons in tungsten diselenide (WSe2) light-emitting transistors (LETs) based on the van der Waals heterostructure is demonstrated. The WSe2 channel is locally doped to simultaneously inject electrons and holes to the 1D region by a local graphene gate. At balanced concentrations of injected electrons and holes, the WSe2 LETs exhibit strong EL with a high external quantum efficiency (EQE) of ≈8.2 % at room temperature. These experimental and theoretical results consistently show that the enhanced EQE could be attributed to dominant exciton emission confined at the 1D region while expelling charged excitons from the active area by precise control of external electric fields. This work shows a promising approach to enhancing the EQE of 2D light-emitting transistors and modulating the recombination of exciton complexes for excitonic devices.

Ultrafast and Bright Quantum Emitters from the Cavity-Coupled Single Perovskite Nanocrystals

Perovskite nanocrystals (NCs) have attracted increasing interest in the realization of single-photon emitters owing to their ease of chemical synthesis, wide spectral tunability, fast recombination rate constant, scalability, and high quantum yield. However, the integration of a single perovskite NC into a photonic structure has yet to be accomplished. In this work, the integration of a highly stable individual zwitterionic ligand-based CsPbBr3 perovskite NC with a circular Bragg grating (CBG) is successfully demonstrated. The far-field radiation pattern of the NC inside the CBG exhibits high directionality toward a low azimuthal angle, which is consistent with the simulation results. A 5.4-fold enhancement in brightness is observed due to an increase in collection efficiency. Moreover, a 1.95-fold increase in the recombination rate constant is achieved. This study offers ultrafast (<100 ps) single-photon emission and an improved brightness of perovskite NCs, which are critical factors for practical quantum optical applications.

Scannable Dual-Focus Metalens with Hybrid Phase

Metalenses with two foci in the longitudinal or transverse direction, called bifocal or dual-focus metalenses, are promising building blocks in tomography techniques, data storage, and optical tweezers. For practical applications, relative movement between the beam and specimen is required, and beam scanning is highly desirable for high-speed operation without vibration. However, dual-focus metalenses employ a hyperbolic phase that experiences off-axis aberrations, which is not suitable for beam scanning. Here, we demonstrated a scannable dual-focus metalens by employing a new phase called "hybrid phase". The hybrid phase consists of a hyperbolic phase inside and a quadratic phase outside to reduce off-axis aberrations while maintaining a high numerical aperture. We show that the two foci of the scannable dual-focus metalens move together without severe distortion for incident angles of up to 2.5°. Our design easily extends to the case of multifocusing, which is essential for various applications ranging from imaging to manipulation.

Deep-learning-based gas identification by time-variant illumination of a single micro-LED-embedded gas sensor

Electronic nose (e-nose) technology for selectively identifying a target gas through chemoresistive sensors has gained much attention for various applications, such as smart factory and personal health monitoring. To overcome the cross-reactivity problem of chemoresistive sensors to various gas species, herein, we propose a novel sensing strategy based on a single micro-LED (μLED)-embedded photoactivated (μLP) gas sensor, utilizing the time-variant illumination for identifying the species and concentrations of various target gases. A fast-changing pseudorandom voltage input is applied to the μLED to generate forced transient sensor responses. A deep neural network is employed to analyze the obtained complex transient signals for gas detection and concentration estimation. The proposed sensor system achieves high classification (~96.99%) and quantification (mean absolute percentage error ~ 31.99%) accuracies for various toxic gases (methanol, ethanol, acetone, and nitrogen dioxide) with a single gas sensor consuming 0.53 mW. The proposed method may significantly improve the efficiency of e-nose technology in terms of cost, space, and power consumption.

Nanowatt-Level Photoactivated Gas Sensor Based on Fully-Integrated Visible MicroLED and Plasmonic Nanomaterials

Photoactivated gas sensors that are fully integrated with micro light-emitting diodes (µLED) have shown great potential to substitute conventional micro/nano-electromechanical (M/NEMS) gas sensors owing to their low power consumption, high mechanical stability, and mass-producibility. Previous photoactivated gas sensors mostly have utilized ultra-violet (UV) light (250-400 nm) for activating high-bandgap metal oxides, although energy conversion efficiencies of gallium nitride (GaN) LEDs are maximized in the blue range (430-470 nm). This study presents a more advanced monolithic photoactivated gas sensor based on a nanowatt-level, ultra-low-power blue (λ_peak  = 435 nm) µLED platform (µLP). To promote the blue light absorbance of the sensing material, plasmonic silver (Ag) nanoparticles (NPs) are uniformly coated on porous indium oxide (In₂ O₃ ) thin films. By the plasmonic effect, Ag NPs absorb the blue light and spontaneously transfer excited hot electrons to the surface of In₂ O₃ . Consequently, high external quantum efficiency (EQE, ≈17.3%) and sensor response (ΔR/R₀ (%) = 1319%) to 1 ppm NO₂ gas can be achieved with a small power consumption of 63 nW. Therefore, it is highly expected to realize various practical applications of mobile gas sensors such as personal environmental monitoring devices, smart factories, farms, and home appliances.

Single Quantum Dot Selection and Tailor-Made Photonic Device Integration using a Nanoscale-Focus Pinspot

Among the diverse platforms of quantum light sources, epitaxially grown semiconductor quantum dots (QDs) are one of the most attractive workhorses for realizing quantum photonic technologies owing to their outstanding brightness and scalability. However, the spatial and spectral randomness of most QDs severely hinders the construction of large-scale photonic platforms. In this work, a methodology is presented to deterministically integrate single QDs with tailor-made photonic structures. A nondestructive luminescence picking method termed as nanoscale-focus pinspot (NFP) is applied using helium-ion microscopy to reduce the luminous QD density while retaining the surrounding medium. A single QD emission is only extracted out of the high-density ensemble QDs. Then the tailor-made photonic structure of a circular Bragg reflector (CBR) is designed and deterministically integrated with the selected QD. Given that the microscopy can image with nanoscale resolution and apply NFP in situ, photonic devices can be deterministically fabricated on target QDs. The extraction efficiency of the NFP-selected QD emission is improved by 25 times after the CBR integration. Since the NFP method only controls the luminescence without destroying the medium, it is applicable to various photonic structures such as photonic waveguides or photonic crystal cavities regardless of materials.

Electrically Driven Sub-Micrometer Light-Emitting Diode Arrays Using Maskless and Etching-Free Pixelation

For decades, group-III-nitride-based light-emitting diodes (LEDs) have been regarded as a light emitting source for future displays by virtue of their novel properties such as high efficiency, brightness, and stability. Nevertheless, realization of high pixel density displays is still challenging due to limitations of pixelation methods. Here, a maskless and etching-free micro-LED (µLED) pixelation method is developed via tailored He focused ion beam (FIB) irradiation technique, and electrically driven sub-micrometer-scale µLED pixel arrays are demonstrated. It is confirmed that optical quenching and electrical isolation effects are simultaneously induced at a certain ion dose (≈10¹⁴ ions cm^-2 ) without surface damage. Furthermore, highly efficient µLED pixel arrays at sub-micrometer scale (square pixel, 0.5 µm side length) are fabricated. Their pixelation and brightness are verified by various optical measurements such as cathodo-, photo-, and electroluminescence. It is expected that the FIB-induced optical quenching and electrical isolation method can pioneer a new defect engineering technology not only for µLED fabrication, but also for sub-micrometer-scale optoelectronic devices.

Enhancement of Single-Photon Purity and Coherence of III-Nitride Quantum Dot with Polarization-Controlled Quasi-Resonant Excitation

III-Nitride semiconductor-based quantum dots (QDs) play an essential role in solid-state quantum light sources because of their potential for room-temperature operation. However, undesired background emission from the surroundings deteriorates single-photon purity. Moreover, spectral diffusion causes inhomogeneous broadening and limits the applications of QDs in quantum photonic technologies. To overcome these obstacles, it is demonstrated that directly pumping carriers to the excited state of the QD reduces the number of carriers generated in the vicinities. The polarization-controlled quasi-resonant excitation is applied to InGaN QDs embedded in GaN nanowire. To analyze the different excitation mechanisms, polarization-resolved absorptions are investigated under the above-barrier bandgap, below-barrier bandgap, and quasi-resonant excitation conditions. By employing polarization-controlled quasi-resonant excitation, the linewidth is reduced from 353 to 272 µeV, and the second-order correlation value is improved from 0.470 to 0.231. Therefore, a greater single-photon purity can be obtained at higher temperatures due to decreased linewidth and background emission.

Dielectric-Engineered High-Speed, Low-Power, Highly Reliable Charge Trap Flash-Based Synaptic Device for Neuromorphic Computing beyond Inference

The coming of the big-data era brought a need for power-efficient computing that cannot be realized in the Von Neumann architecture. Neuromorphic computing which is motivated by the human brain can greatly reduce power consumption through matrix multiplication, and a device that mimics a human synapse plays an important role. However, many synaptic devices suffer from limited linearity and symmetry without using incremental step pulse programming (ISPP). In this work, we demonstrated a charge-trap flash (CTF)-based synaptic transistor using trap-level engineered Al₂O₃/Ta₂O₅/Al₂O₃ gate stack for successful neuromorphic computing. This novel gate stack provided precise control of the conductance with more than 6 bits. We chose the appropriate bias for highly linear and symmetric modulation of conductance and realized it with very short (25 ns) identical pulses at low voltage, resulting in low power consumption and high reliability. Finally, we achieved high learning accuracy in the training of 60000 MNIST images.

Ultra-Low-Power E-Nose System Based on Multi-Micro-LED-Integrated, Nanostructured Gas Sensors and Deep Learning

As interests in air quality monitoring related to environmental pollution and industrial safety increase, demands for gas sensors are rapidly increasing. Among various gas sensor types, the semiconductor metal oxide (SMO)-type sensor has advantages of high sensitivity, low cost, mass production, and small size but suffers from poor selectivity. To solve this problem, electronic nose (e-nose) systems using a gas sensor array and pattern recognition are widely used. However, as the number of sensors in the e-nose system increases, total power consumption also increases. In this study, an ultra-low-power e-nose system was developed using ultraviolet (UV) micro-LED (μLED) gas sensors and a convolutional neural network (CNN). A monolithic photoactivated gas sensor was developed by depositing a nanocolumnar In₂O₃ film coated with plasmonic metal nanoparticles (NPs) directly on the μLED. The e-nose system consists of two different μLED sensors with silver and gold NP coating, and the total power consumption was measured as 0.38 mW, which is one-hundredth of the conventional heater-based e-nose system. Responses to various target gases measured by multi-μLED gas sensors were analyzed by pattern recognition and used as the training data for the CNN algorithm. As a result, a real-time, highly selective e-nose system with a gas classification accuracy of 99.32% and a gas concentration regression error (mean absolute) of 13.82% for five different gases (air, ethanol, NO₂, acetone, methanol) was developed. The μLED-based e-nose system can be stably battery-driven for a long period and is expected to be widely used in environmental internet of things (IoT) applications.

Perioperative risk and benefit of antiplatelet therapy in patients undergoing non-cardiac surgery within 1 year after percutaneous coronary intervention with second-generation drug-eluting stents

Background

Antiplatelet therapy (APT) in patients undergoing non-cardiac surgery (NCS) after percutaneous coronary intervention (PCI) is still on debate due to its opposite effects which are to prevent from cardiovascular events and to cause bleeding. There is no apparent consensus on how to determine perioperative APT strategy within 1 year after PCI. Therefore, we investigated the risk and benefit of APT in NCS within 1 year after PCI.

Methods

Patients undergoing NCS after PCI with second-generation drug-eluting stents are retrospectively included from multicenter cohort of 8 medical centers in Korea. Perioperative clinical event within 30 days after NCS was recorded. Net adverse clinical event (NACE) including all cause death, major adverse cardiac event (MACE, a composite of cardiac death, myocardial infarction, and stent thrombosis) and major bleeding were evaluated. To overcome bias, propensity score covariate adjustment was performed using logistic regression analysis to generate propensity scores for patients of both APT strategies.

Results

Total 1130 patients (median age 69 years, female 30.5%) undergoing NCS within 1 year after PCI were eligible in the cohort. Study population included 55.1% patients suffered from ACS and 22.5% underwent complex PCI. NCS included 45.8% intermediate-to-high risk surgery and 10.7% urgent or emergent surgery. APT was continued during NCS in 62.7% of the patients. More patients continued DAPT (48% vs. 32%, p&lt;0.001) among the patients who underwent NCS within 6 months after PCI than those who underwent NCS after 6 months. There were 49 NACE (4.3%), 16 MACE (1.4%) and 23 major bleeding events (2.0%), respectively. Continuing APT was associated with a lower risk of NACE (Adjusted hazard ratio [HR], 0.49; 95% confidence interval [CI], 0.27–0.89; p=0.020)) and MACE (Adjusted HR, 0.35; 95 CI, 0.12–0.96; p=0.042). Subgroup analysis showed a tendency that continuing APT might be favorable than discontinuing APT in terms of MACE in patients who were diagnosed with ACS, underwent complex PCI, or underwent NCS within 6 months after PCI.

Conclusions

About two thirds of the patients were continuing APT during NCS. Our findings may support a careful consideration of APT continuation for some of the patients who are undergoing NCS within 1 year after PCI.

Funding Acknowledgement

Type of funding sources: None.

A Rare Case of Oligodendroglioma in Sacrococcygeal Mature Teratoma Diagnosed in Preterm Infant

Sacrococcygeal teratoma is the most common congenital tumor in neonates, and is reported in approximately 1/35,000 to 1/40,000 live births. Oligodendroglioma is a rare central nervous system tumor that is usually found in the cerebral hemisphere of young and middle aged adults. When associated with a teratoma, it is mainly identified in ovarian teratoma in adolescents and adults. We describe a rare case of a preterm infant with oligodendroglioma in a mature sacrococcygeal teratoma. The male neonate was born at a gestational age of 30 weeks with a protruding mass in the sacrococcygeal region. Pelvic magnetic resonance imaging showed a sacrococcygeal teratoma of approximately 11 cm comprising fat components and skeletal structure, that extended from the anterior part of the sacrum to the abdominal cavity. Radical resection was performed at 36 days of age. Macroscopically, the resected intra-abdominal mass had the characteristics of a cystic lesion, and the intrapelvic mass was a predominantly solid mixed cystic-solid lesion. Histologically, this solid lesion in the intrapelvic mass was composed of mature glial tissue, which comprised as a proliferation of monotonous cells with small and round nuclei, surrounded by a perinuclear halo (“fried egg” appearance). Additionally, these cells were immunohistochemically positive for glial fibrillary acidic protein. These findings confirmed the diagnosis of oligodendroglioma in sacrococcygeal mature teratoma. After the treatment, no recurrence was observed during the follow-up period, and no additional intervention was required. However, the patient is undergoing treatment for voiding dysfunction caused by a neurogenic bladder.

Distinctive clinical features of spontaneous pneumoperitoneum in neonates: A retrospective analysis

BACKGROUND

Spontaneous pneumoperitoneum (SP) without gastrointestinal perforation rarely occurs in neonates, with most SP cases being idiopathic. Although SP usually follows a benign clinical course with favorable prognosis, it can become life-threatening in certain situations. In these cases, urgent surgical intervention may be required. Therefore, it may be difficult to decide when or how to perform prompt interventions.

AIM

To demonstrate the distinct clinical features of SP to guide appropriate management by comparing characteristics between SP and typical pneumoperitoneum secondary to gastrointestinal perforation.

METHODS

We retrospectively reviewed electronic medical records and identified 37 neonates with radiological evidence of pneumoperitoneum who were treated at our institution. Clinical variables were compared between neonates with SP without gastrointestinal perforation (Group A) and those with pneumoperitoneum secondary to gastrointestinal perforation (Group B). Clinical variables between groups were compared using Student’s t-test and the chi-square test. The risk factors related to mortality were examined using multi-logistic regression analysis.

RESULTS

Group A comprised 35.1% (13/37) of the patients. The frequency of persistent pulmonary hypertension (53.8%) and pneumothorax (46.2%) before the development of pneumoperitoneum was significantly higher in group A than in group B (P = 0.004). Platelet count and partial pressure of arterial oxygen (PaO2) were significantly lower in group A (P = 0.015 and 0.025, respectively). Overall mortality was significantly higher in group A than in group B (76.9% vs 16.7%, P = 0.001). Only preterm infants were significantly associated with high mortality (P = 0.041; odds ratio = 18.0). Accompaniment with persistent pulmonary hypertension and pneumothorax were also significantly high (P = 0.004) in group A, but these were not strongly associated with high mortality.

CONCLUSION

This study identified a higher mortality rate in patients with SP than that described in previous reports. Neonates with SP were more likely to have thrombocytopenia, pneumothorax, and persistent pulmonary hypertension. Prematurity was the most significant factor affecting mortality.

Perinatal Prognostic Factors for Congenital Diaphragmatic Hernia: A Korean Single-Center Study

Purpose: This study aimed to identify prognostic factors based on treatment outcomes for congenital diaphragmatic hernia (CDH) at a single-center and to identify factors that may improve these outcomes.Methods: Thirty-five neonates diagnosed with CDH between January 2011 and December 2021 were retrospectively analyzed. Pre- and postnatal factors were correlated and analyzed with postnatal clinical outcomes to determine the prognostic factors. Highest oxygenation index (OI) within 24 hours of birth was also calculated. Treatment strategy and outcome analysis of published literatures were also performed.Results: Overall survival rate of this cohort was 60%. Four patients were unable to undergo anesthesia and/or surgery. Three patients who commenced extracorporeal membrane oxygenation (ECMO) post-surgery were non-survivors. Compared to the survivor group, the non-survivor group had a significantly higher occurrence of pneumothorax on the first day, need for high-frequency ventilator and inhaled nitric oxide use, and high OI within the first 24 hours. The non-survivor group showed an early trend towards the surgery timing and a greater number of patch closures. Area under the receiver operating characteristic curve was 0.878 with a sensitivity of 76.2% and specificity of 92.9% at an OI cutoff value of 7.75.Conclusion: OI within 24 hours is a valuable predictor of survival. It is expected that the application of ECMO based on OI monitoring may help improve the opportunity for surgical repair, as well as the prognosis of CDH patients.

Influence of wafer quality on chip size-dependent efficiency variation in blue and green micro light-emitting diodes

We propose a key factor associated with both surface recombination velocity and radiative efficiency of an LED to estimate its chip size-dependent radiative efficiencies. The validity of the suggested factor is verified through experimental comparison between various LED wafers. Efficiencies of micro-LEDs from a blue and two green LED wafers are examined by temperature-dependent photoluminescence experiments. Surface recombination velocities are extracted from chip size dependent time-resolved PL results. Possible explanations on the reason why two green wafers show different properties are also given. With the suggested factor, we can provide more accurate prediction on the chip size-dependent efficiency of an LED wafer.

Wide-Field Super-Resolution Optical Fluctuation Imaging through Dynamic Near-Field Speckle Illumination

Stochastic optical fluctuation imaging (SOFI) generates super-resolution fluorescence images by emphasizing the positions of fluorescent emitters via statistical analysis of their on-and-off blinking dynamics. In SOFI with speckle illumination (S-SOFI), the diffraction-limited grain size of the far-field speckles prevents independent blinking of closely located emitters, becoming a hurdle to realize the full super-resolution granted by SOFI processing. Here, we present a surface-sensitive super-resolution technique exploiting dynamic near-field speckle illumination to bring forth the full super-resolving power of SOFI without blinking fluorophores. With our near-field S-SOFI technique, up to 2.8- and 2.3-fold enhancements in lateral spatial resolution are demonstrated with computational and experimental fluorescent test targets labeled with conventional fluorophores, respectively. Fluorescent beads separated by 175 nm are also super-resolved by near-field speckles of 150 nm grain size, promising sub-100 nm resolution with speckle patterns of much smaller grain size.

Spatially isolated neutral excitons via clusters on trilayer MoS2

In spite of having a large exciton binding energy, two-dimensional (2D) transition metal dichalcogenides (TMDs) are limited as light-emitting materials because the spectral weight of neutral excitons decreases exponentially with increasing the excitation density. That is, neutral excitons easily transfer to trions, and exciton-exciton annihilation (EEA) occurs due to the strengthening of exciton kinetic energy in the layered structure. In here, we come up with an isolated neutral exciton system, maintaining its high spectral weight when the carrier density increased, which is achieved via MoS₂ clusters on a MoS₂ trilayer directly synthesized by metal-organic chemical vapor deposition (MOCVD). While increasing the excitation density, trions are decomposed by spatial confinement at the saturation level of its full width at half maximum (FWHM), and simultaneously the spectral weight of neutral excitons restarts to increase. Furthermore, we reveal the causality relationship between trions and B excitons, providing a keen insight into organic interactions among radiative recombination processes in 2D TMDs.

Surgical perspectives of symptomatic omphalomesenteric duct remnants: Differences between infancy and beyond

BACKGROUND

The clinical manifestations of omphalomesenteric duct remnant (OMDR) can vary with the age at diagnosis, from asymptomatic incidental findings to symptoms related to gastrointestinal complications. The lifelong complication rates are reported as 4%-34%, and complications are more common in patients younger than 2 years of age. The authors attempted to identify different clinical features and management for the various pediatric age groups.

AIM

To find surgical perspectives for the pediatric age-related variants of OMDR and make recommendations for optimal management.

METHODS

The medical records of pediatric patients diagnosed with OMDR were reviewed retrospectively. Fifteen patients diagnosed based on incidental findings during other surgeries were excluded. The patients were divided into two groups based on age: < 12 mo (infants) and > 12 mo (beyond infancy). We analyzed the demographic characteristics, clinical manifestations, diagnostic tools, surgical procedures, and clinical outcomes of the patients and compared them for the age groups. Chi-squared and Fisher's exact tests were used for nominal scales and a Mann-Whitney test was used for ratio scales.

RESULTS

A total of 35 patients (7 infants, 28 children beyond infancy) were finally included. In both groups, Meckel's diverticulum (MD) was the most common type of OMDR, while umbilical lesions were more common in the infant group (P = 0.006). Hematochezia and abdominal pain were common in the beyond infancy group, while umbilical lesions were the most frequent symptoms in the infant group. Several diagnostic tools were used, but Meckel's scan was most useful in diagnosing OMDR in patients with painless rectal bleeding. Minimally invasive surgery was more commonly performed for children than for infants (P = 0.016). Single-incision laparoscopic surgery (SILS) was performed for fifteen patients who underwent laparoscopic surgery. There were only three cases of postoperative complications, and all patients survived in good condition.

CONCLUSION

The clinical type of OMDR varies with age, umbilical lesions in infants, and MD beyond infancy. SILS is effective for managing children with MD regardless of age.

Scrotal pyocele secondary to gastrointestinal perforation in infants: a case series

Pyocele in infants is rarely described in the literature, but it is an emergent condition that requires rapid recognition and treatment to prevent testicular loss. If peritonitis due to gastrointestinal perforation occurs, abdominal contamination may spread through a patent processus vaginalis in an infant, which may lead to pyocele. We report the cases of three infants with scrotal pyocele due to the spread of infection or inflammatory material from the intraperitoneal cavity through a patent processus vaginalis. Two infants were surgically treated, while the other was treated with percutaneous aspiration and intravenous antibiotic administration. Although rare, pyocele should be considered in the differential diagnosis of acute scrotum in infants, especially in infants who previously had peritonitis due to gastrointestinal perforation.

Assessment of defecation function beyond infantile period for transanal single-stage endorectal pull-through in Hirschsprung disease

Purpose

Transanal single-stage endorectal pull-through (TERPT) procedure for patients with Hirschsprung disease (HD) has favorable outcomes, with a lower complication rate. Nevertheless, various degrees of bowel dysfunction and fecal incontinence can persist for a long time in some patients. The aim of this study was to assess the mid- and long-term outcomes of TERPT performed during the infantile period after the completion of toilet training.

Methods

We retrospectively reviewed 82 patients aged ≥4 years who underwent TERPT during the infantile period after the pathological diagnosis of HD between 2001 and 2013. Functional outcomes were investigated according to the answers of the Bowel Function Score (BFS) questionnaire, a previously validated 7-item questionnaire about bowel habits. Normal values were obtained in a previous study on BFS for children in Western countries, and a one-sample t-test was used for statistical analysis.

Results

Overall, BFS was similar in all investigated age groups. On comparing fecal soiling and social problems between the HD and normal populations, a lower score at an early age in patients with HD was noted; however, the scores became similar when the patients were 7 years of age. Stool frequency decreased continuously but was not significantly different between the 2 groups.

Conclusion

The functional outcomes of TERPT performed during the infantile period, after completing toilet training, were similar to that of the normal population. In most cases, uncomfortable symptoms were diminished and functions improved with age.

Correlation between Exposure to Fine Particulate Matter (PM2.5) during Pregnancy and Congenital Anomalies: Its Surgical Perspectives

BACKGROUND

Fine particulate matter (PM_2.5) can easily penetrate blood vessels and tissues through the human respiratory tract and cause various health problems. Some studies reported that particular matter (PM) exposure during pregnancy is associated with low birth weight or congenital cardiovascular anomalies. This study aimed to investigate the correlation between the degree of exposure to PM ≤ 2.5 μm (PM_2.5) during pregnancy and congenital anomalies relevant to the field of pediatric surgery.

METHODS

Mother-infant dyads with registered addresses in the Metropolitan City were selected during 3 years. The electronic medical records of mothers and neonates were retrospectively analyzed, with a focus on maternal age at delivery, date of delivery, gestation week, presence of diabetes mellitus (DM) or hypertension, parity, the residence of the mother and infant, infant sex, birth weight, Apgar score, and presence of congenital anomaly. The monthly PM_2.5 concentration from the first month of pregnancy to the delivery was computed based on the mothers' residences.

RESULTS

PM_2.5 exposure concentration in the second trimester was higher in the congenital anomaly group than in the non-congenital anomaly group (24.82 ± 4.78 µg/m³, P = 0.023). PM_2.5 exposure concentration did not affect the incidence of nervous, cardiovascular, and gastrointestinal anomalies. While statistically insignificant, the groups with nervous, cardiovascular, gastrointestinal, musculoskeletal, and other congenital anomalies were exposed to higher PM_2.5 concentrations in the first trimester compared with their respective counterparts. The effect of PM_2.5 concentration on the incidence of congenital anomalies was significant even after adjusting for the mother's age, presence of DM, hypertension, and parity. The incidence of congenital anomalies increased by 26.0% (95% confidence interval of 4.3% and 49.2%) per 7.23 µg/m³ elevation of PM_2.5 interquartile range in the second trimester.

CONCLUSIONS

The congenital anomaly group was exposed to a higher PM_2.5 concentration in the second trimester than the non-congenital anomaly group. The PM_2.5 exposure concentration level in the first trimester tended to be higher in groups with anomalies than those without anomalies. This suggests that continuous exposure to a high PM_2.5 concentration during pregnancy influences the incidence of neonatal anomalies in surgical respects.

Highly Efficient Vacuum-Evaporated CsPbBr3 Perovskite Light-Emitting Diodes with an Electrical Conductivity Enhanced Polymer-Assisted Passivation Layer

Highly efficient vacuum-deposited CsPbBr₃ perovskite light-emitting diodes (PeLEDs) are demonstrated by introducing a separate polyethylene oxide (PEO) passivation layer. A CsPbBr₃ film deposited on the PEO layer via thermal co-evaporation of CsBr and PbBr₂ exhibits an almost 50-fold increase in photoluminescence quantum yield intensity compared to a reference sample without PEO. This enhancement is attributed to the passivation of interfacial defects of the perovskite, as evidenced by temperature-dependent photoluminescence measurements. However, direct application of PEO to an LED device is challenging because of the electrically insulating nature of PEO. This issue is solved by doping PEO layers with MgCl₂. This strategy results in an enhanced luminance and external quantum efficiency (EQE) of up to 6887 cd m^-2 and 7.6%, respectively. To the best of our knowledge, this is the highest EQE reported to date among vacuum-deposited PeLEDs.

Nanoscale Focus Pinspot for High-Purity Quantum Emitters via Focused-Ion-Beam-Induced Luminescence Quenching

Epitaxially grown quantum dots (QDs), especially embedded in photonic structures, play an essential role in various quantum photonic systems as on-demand single-photon sources. However, these QDs often suffer from adjacent unwanted emitters, which contribute to the background noise of the QD emission and fundamentally limit the single-photon purity. In this paper, a nanoscale focus pinspot (NFP) technique using focused-ion-beam-induced luminescence quenching enables us to improve single-photon purity from site-controlled QD as a proof-of-concept experiment. The optical quality of the QD emission is not degraded while the signal-to-noise ratio of the QD is improved. Moreover, the QD after the NFP technique reveals the single-photon nature at further elevated temperatures owing to the reduced background noise. As the NFP technique is nondestructive, it retains the apparent physical structures and photonic functions, thereby indicating its promising potential for applying diverse high-purity quantum emitters, particularly integrated in photonic devices and circuits.

Skin autofluorescence in people with type 1 diabetes and people without diabetes: An eight-decade cross-sectional study with evidence of accelerated aging and associations with complications

AIM

To measure skin autofluorescence in youth (<18 y.o.) and adults (≥18 y.o.) and to assess its relationship with type 1 diabetes, chronic complications and smoking.

METHODS

In a cross-sectional study (n = 383) skin autofluorescence was measured in 269 people with type 1 diabetes (67 with vascular complications) and 114 people without diabetes, covering eight decades of age. Associations of skin autofluorescence with demographics and traditional risk factors were assessed.

RESULTS

Skin autofluorescence increased with age in people with diabetes: for those with complications it increased by a mean ± se of 0.029 ± 0.003 arbitrary units per year (r = 0.76) and, for those without complications, it increased by 0.028 ± 0.002 arbitrary units (r = 0.77). These increases were higher than for people without diabetes, whose skin autofluorescence increased by 0.022 ± 0.002 arbitrary units (r = 0.78) per year (p = 0.004). Mean ±se age-adjusted skin autofluorescence was higher in people with diabetes complications vs people without diabetes complications (1.85 ± 0.04 vs 1.66 ± 0.02 arbitrary units) and people without diabetes (1.48 ± 0.03 arbitrary units; all P < 0.0001). Age-adjusted skin autofluorescence was higher in current smokers and recent ex-smokers vs non-smokers and longer-term ex-smokers (1.86 ± 0.06 vs 1.63 ± 0.02 arbitrary units; P = 0.0005). Skin autofluorescence area under the receiver-operating characteristic curve was 0.89 (95% CI 0.85-0.94) for retinopathy and 0.56 (95% CI 0.47-0.65) for nephropathy.

CONCLUSIONS

Skin autofluorescence increases with age, but faster in people with diabetes, particularly in those with complications and in smokers, consistent with accelerated aging. Skin autofluorescence may facilitate complication screening and prediction. Longitudinal studies are merited.

Absent or impaired rectoanal inhibitory reflex as a diagnostic factor for high-grade (grade III-V) rectal prolapse: a retrospective study

Background

Clinically diagnosing high-grade (III–V) rectal prolapse might be difficult, and the prolapse can often be overlooked. Even though defecography is the significant diagnostic tool for rectal prolapse, it is noticed that rectoanal inhibitory reflex (RAIR) can be associated with rectal prolapse. This study investigated whether RAIR can be used as a diagnostic factor for rectal prolapse.

Methods

In this retrospective study, we evaluated 107 patients who underwent both anorectal manometry and defecography between July 2012 and December 2019. Rectal prolapse was classified in accordance with the Oxford Rectal Prolapse Grading System. Patients in the high-grade (III–V) rectal prolapse (high-grade group, n = 30), and patients with no rectal prolapse or low-grade (I, II) rectal prolapse (low-grade group, n = 77) were analyzed. Clinical variables, including symptoms such as fecal incontinence, feeling of prolapse, and history were collected. Symptoms were assessed using yes/no surveys answered by the patients. The manometric results were also evaluated.

Results

Frequencies of fecal incontinence (p = 0.002) and feeling of prolapse (p < 0.001) were significantly higher in the high-grade group. The maximum resting (77.5 vs. 96 mmHg, p = 0.011) and squeezing (128.7 vs. 165 mmHg, p = 0.010) anal pressures were significantly lower in the high-grade group. The frequency of absent or impaired RAIR was significantly higher in the high-grade group (19 cases, 63% vs. 20 cases, 26%, p < 0.001). In a multivariate analysis, the feeling of prolapse (odds ratio [OR], 23.88; 95% confidence interval [CI], 4.43–128.78; p < 0.001) and absent or impaired RAIR (OR, 5.36; 95% CI, 1.91–15.04, p = 0.001) were independent factors of high-grade (III–V) rectal prolapse. In addition, the percentage of the absent or impaired RAIR significantly increased with grading increase of rectal prolapse (p < 0.001). The sensitivity of absent or impaired RAIR as a predictor of high-grade prolapse was 63.3% and specificity 74.0%.

Conclusions

Absent or impaired RAIR was a meaningful diagnostic factor of high-grade (III–V) rectal prolapse. Furthermore, the absent or impaired reflex had a positive linear trend according to the increase of rectal prolapse grading.

A Flash-Induced Robust Cu Electrode on Glass Substrates and Its Application for Thin-Film μLEDs

A robust Cu conductor on a glass substrate for thin-film μLEDs using the flash-induced chemical/physical interlocking between Cu and glass is reported. During millisecond light irradiation, CuO nanoparticles (NPs) on the display substrate are transformed into a conductive Cu film by reduction and sintering. At the same time, intensive heating at the boundary of CuO NPs and glass chemically induces the formation of an ultrathin Cu₂ O interlayer within the Cu/glass interface for strong adhesion. Cu nanointerlocking occurs by transient glass softening and interface fluctuation to increase the contact area. Owing to these flash-induced interfacial interactions, the flash-activated Cu electrode exhibits an adhesion energy of 10 J m^-2 , which is five times higher than that of vacuum-deposited Cu. An AlGaInP thin-film vertical μLED (VLED) forms an electrical interconnection with the flash-induced Cu electrode via an ACF bonding process, resulting in a high optical power density of 41 mW mm^-2 . The Cu conductor enables reliable VLED operation regardless of harsh thermal stress and moisture infiltration under a high-temperature storage test, temperature humidity test, and thermal shock test. 50 × 50 VLED arrays transferred onto the flash-induced robust Cu electrode show high illumination yield and uniform distribution of forward voltage, peak wavelength, and device temperature.

Changes in the prevalence of index diseases in pediatric surgery: case analysis of single national children’s hospital

Pusan National University Children’s Hospital (PNUCH) opened in November 2008 as the second National Children’s Hospital in Korea and celebrated its 10th anniversary in 2018. In the last decade, birth rates and pediatric populations have been declining sharply and has been more serious in Busan, Ulsan, and Gyeongsangnam-do where the PNUCH is located, affecting the prevalence of index diseases. The number of the index diseases was investigated by year according to changes in the population. Patients who underwent surgery at PNUCH for 10 years were included. Changes in pediatric population and the number of live births were analyzed using the data from Statistics Korea. The number of the index diseases was analyzed retrospectively through the review of electronic medical records. Statistical analysis was performed through Poisson regression. The number of live births and pediatric population decreased from 69,528 to 48,600 (30.1%) and 1,880,284 to 1,444,961 (23.2%), respectively. Operations of pediatric surgery decreased by 32.3% compared to that during the peak season, but the prevalence rate ratio of the pediatric population increased to 1.03 (<i>P</i><0.001). The number of emergency operation increased due to the largest surge in acute appendicitis operations. Both esophageal atresia and Hirschsprung disease decreased, while hypertrophic pyloric stenosis significantly increased. The absolute number of pediatric surgery cases decreased. However, considering the changes in pediatric population and the number of live births, the relative number of pediatric surgery cases does not changed. The decrease in the number of each disease would be related to the decrease in pediatric population and the number of live births. We should consider the increase of emergency operations such as acute appendicitis.

Friction Control by Deformation Mode in Nanopatterned Amorphous Carbon

Traditionally, the manipulation of contact mechanisms has been adopted as the primary strategy to tailor the friction properties of surfaces. On the contrary, the detaching process involving the local deformation and failure at the interface has been considered relatively less important. Here, we present a new approach toward the friction control of amorphous carbon through the plasticity and resultant transition of deformation mode on nanopatterned surfaces. Depending on the topography of the nanopatterns, the mechanical responses of the surfaces alter from elastic fracture to plastic flow, through which the friction coefficient changes by a factor of 5 without manipulation of the intrinsic structure of the material.

Control of the 3-Fold Symmetric Shape of Group III-Nitride Quantum Dots: Suppression of Fine-Structure Splitting

Controlling the in-plane symmetry of wide-bandgap semiconductor quantum dots (QDs) is essential for room temperature quantum photonic applications using polarization entangled photon pairs. Herein, we report the formation of 3-fold symmetric group III-nitride QDs at the apex of a triangular pyramid via a self-limited growth mechanism. We employed the in-plane rotational symmetry of the c-plane of a Wurtzite crystal and the large built-in piezoelectric field to reduce fine-structure splitting. The QDs exhibit emission that is distinguishable from that of sidewall quantum wells, and the biexciton-exciton cascade possesses a single-photon nature. We observed the relatively low optical polarization anisotropy and small fine structure splitting under the measurement limit (270 μeV) with the 3-fold symmetric QD. In contrast with current strategies that consider group III-nitride QDs as strongly polarized single-photon emitters, our approach for controlling the QD symmetry provides a new perspective on such QDs, as polarization-entangled photon pairs.

Full and gradient structural colouration by lattice amplified gallium nitride Mie-resonators

The hybridised resonances between Mie-scatterers and lattice resonances, i.e. quasi-guided mode resonances, are investigated. The scattering of the Mie-resonators is improved by the first order of transmitted diffracted light which is coupled to the lattice formed by the Mie-resonators. The conditions of coupling are dependent on the refractive index of the substrate and the effective refractive index of the unit cell of the resonators. Based on the momentum matching conditions, the cut-off wavelength of coupling and the amount of the amplification can be controlled. As a proof-of-concept application of this framework, gallium nitride metasurfaces are designed to produce metasurfaces that display structural colour. Palettes of full spectral colour and gradients are successfully demonstrated. The hue of the colour can be controlled by changing the periodicity of the unit cell at a fixed filling ratio of Mie-scatterer radius to unit cell periodicity, since the increase in periodicity redshifts the cut-off wavelength of the lattice resonance conditions, identified as the Rayleigh anomaly. The brightness of the colour can be tuned by adjusting the filling ratio of the unit cell. Consequently, the proposed framework may provide a fundamental guideline to design spectral filters made up of low-index Mie-scatterers for various applications.

Alimentary Tract Duplication in Pediatric Patients: Its Distinct Clinical Features and Managements

PURPOSE

Alimentary tract duplication (ATD) is a rare congenital condition that may occur throughout the intestinal tract. Clinical symptoms are generally related to the involved site, size of duplication, or associated ectopic mucosa. This study aimed to identify clinical implications by anatomical locations and age group and then suggest a relevant management according to its distinct features.

METHODS

We retrospectively reviewed the clinical data of pediatric patients who received a surgical management due to ATD. Furthermore, data including patients' demographics, anatomical distribution of the duplication, clinical features according to anatomical variants, and outcomes were compared.

RESULTS

A total of 25 patients were included in this study. ATD developed most commonly in the midgut, especially at the ileocecal region. The most common clinical presentation was abdominal pain, a sign resulting from intestinal obstruction, gastrointestinal bleeding, and intussusception. The non-communicating cystic type was the most common pathological feature in all age groups. Clinically, prenatal detection was relatively low; however, it usually manifested before the infantile period. A laparoscopic procedure was performed in most cases (18/25, 72.0%), significantly in the midgut lesion (p=0.012).

CONCLUSION

ATD occurs most commonly at the ileocecal region, and a symptomatic one may usually be detected before the early childhood period. Surgical management should be considered whether symptom or not regarding its symptomatic progression, and a minimal invasive procedure is the preferred method, especially for the midgut lesion.

AlGaN Deep-Ultraviolet Light-Emitting Diodes with Localized Surface Plasmon Resonance by a High-Density Array of 40 nm Al Nanoparticles

We present a remarkable improvement in the efficiency of AlGaN deep-ultraviolet light-emitting diodes (LEDs) enabled by the coupling of localized surface plasmon resonance (LSPR) mediated by a high-density array of Al nanoparticles (NPs). The Al NPs with an average diameter of ∼40 nm were uniformly distributed near the Al_0.43Ga_0.57N/Al_0.50Ga_0.50N multiple quantum well active region for coupling 285 nm emission by block copolymer lithography. The internal quantum efficiency is enhanced by 57.7% because of the decreased radiative recombination lifetime by the LSPR. As a consequence, the AlGaN LEDs with an array of Al NPs show 33.3% enhanced electroluminescence with comparable electrical properties to those of reference LEDs without Al NPs.

A discrete core-shell-like micro-light-emitting diode array grown on sapphire nano-membranes

A discrete core-shell-like micro-light-emitting diode (micro-LED) array was grown on a 100 nm-thick sapphire nano-membrane array without harmful plasma etching for chip singulation. Due to proper design for the sapphire nano-membrane array, an array of multi-faceted micro-LEDs with size of 4 μm × 16 μm was grown. Threading dislocation density in the micro-LED formed on sapphire nano-membrane was reduced by 59.6% due to the sapphire nano-membranes, which serve as compliant substrates, compared to GaN formed on a planar substrate. Enhancements in internal quantum efficiency by 44% and 3.3 times higher photoluminescence intensity were also observed from it. Cathodoluminescence emission at 435 nm was measured from c-plane multiple quantum wells (MQWs), whereas negligible emissions were detected from semi-polar sidewall facets. A core-shell-like MQWs were formed on all facets, hopefully lowering concentration of non-radiative surface recombination centers and reducing leakage current paths. This study provides an attractive platform for micro-LEDs by using sapphire nano-membrane.

Perforated Choledochal Cyst: Its Clinical Implications in Pediatric Patient

PURPOSE

Perforation of choledochal cyst (CC) is a relatively rare clinical presentation in pediatric populations and difficult to predict preoperatively. We assess the clinical implications by comparing clinical parameters based on a single-center experience between perforated and nonperforated CC to facilitate the appropriate management for future interventions.

METHODS

A total of 92 cases of CC in pediatric patients (aged <18 years) who received surgical management between January 2003 and December 2018 at a Pusan National University Children's Hospital were reviewed. After screening the clinical features of perforated cases, we compared the demographic findings, clinical characteristics, and some laboratory results between the perforated and nonperforated groups.

RESULTS

Perforated CC was identified in 8 patients (8.7%), and nonperforated CC in 84 patients (91.3%). Perforation can be classified into three categories: free perforation of cyst (3 cases), pinpoint perforation of cyst (2 cases), and necrotic change of cyst (3 cases). CC perforation occurred significantly more commonly in patients aged <24 months. Clinically, the perforated group showed significantly higher frequency of fever and higher C-reactive protein (CRP) level during the initial visit.

CONCLUSION

Perforation is more likely to be suspected in patients aged <24 months presenting together with fever and high CRP level in the initial visit. It is also necessary to keep in mind that it indicates not only a possibility of complicated disease status regardless of its association with stones but also a difficulty of applying a minimal invasive procedure and relatively increased length of hospital stay.

Three-dimensional hierarchical semi-polar GaN/InGaN MQW coaxial nanowires on a patterned Si nanowire template

We have demonstrated for the first time the hybrid development of next-generation 3-D hierarchical GaN/InGaN multiple-quantum-well nanowires on a patterned Si nanowire-template. The patterned Si nanowire-template is fabricated using metal-assisted chemical-etching, and the conformal growth of the GaN/InGaN multiple-quantum-well (MQW) coaxial nanowires is conducted using metal-organic-chemical-vapor-deposition by the two-step growth approach of vapor-liquid-solid for the GaN core and vapor-solid for the GaN/InGaN MQW shells. The growth directions of the GaN nanowires are confirmed by transmission electron microscopy and selected area electron diffraction patterns. The emission of the GaN/InGaN MQW nanowire is tuned from 440 nm to 505 nm by increasing the InGaN quantum-well thickness. The carrier dynamics were evaluated by performing temperature-dependent time-resolved photoluminescence measurement, and the radiative lifetime of photogenerated electron-hole pairs was found to range from 30 to 35 ps. A very high IQE of 56% was measured due to the suppressed quantum-confined Stark effect which was enabled by the semi-polar growth facet of the GaN/InGaN MQWs. The demonstration of the growth of the hybrid 3-D hierarchical GaN/InGaN MQW nanowires provides a seamless platform for a broad range of multifunctional optical and electronic applications.

A broadband ultraviolet light source using GaN quantum dots formed on hexagonal truncated pyramid structures

Group III-nitride semiconductor-based ultraviolet (UV) light emitting diodes have been suggested as a substitute for conventional arc-lamps such as mercury, xenon and deuterium arc-lamps, since they are compact, efficient and have a long lifetime. However, in previously reported studies, group III-nitride UV light emitting diodes did not show a broad UV spectrum range as conventional arc-lamps, which restricts their application in fields such as medical therapy and UV spectrophotometry. Here, we propose GaN quantum dots (QDs) grown on different facets of hexagonal truncated pyramid structures formed on a conventional (0001) sapphire substrate. A hexagonal truncated GaN pyramid structure includes {101̄1} semipolar facets as well as a (0001) polar facet, which have intrinsically different piezoelectric fields and growth rates of GaN QDs. Consequently, we successfully demonstrated a plateau-like broadband UV spectrum ranging from ∼400 nm (UV-A) to ∼270 nm (UV-C) from the GaN QDs. In addition, at the top-edge of the truncated pyramid structure, a strain was locally suppressed compared to the center of the truncated pyramid structure. As a result, various emission wavelengths in the UV range were achieved from the GaN QDs grown on the sidewall, top-edge and top-center of hexagonal truncated pyramid structures, which ultimately provide a broadband UV spectrum with high efficiency.

Monolithic Micro Light-Emitting Diode/Metal Oxide Nanowire Gas Sensor with Microwatt-Level Power Consumption

High-performance, monolithic photoactivated gas sensors based on the integration of gas-sensitive semiconductor metal oxide nanowires on micro light-emitting diodes (μLEDs) are introduced. The μLEDs showed improved irradiance and energy conversion efficiency (i.e., external quantum efficiency, EQE), as the size of LEDs was reduced from 200 × 200 μm² (irradiance of 46.5 W/cm² and EQE of 4%) to 30 × 30 μm² (irradiance of 822.4 W/cm² and EQE of 9%). Gas-sensitive zinc oxide (ZnO) nanowires were directly synthesized on top of the μLED through a hydrothermal reaction. The direct contact between the sensing component and μLED sensor platform leads to high light coupling efficiency, minimizing power consumption of the sensor. Furthermore, the sensing performance (i.e., sensitivity) at optimal operating power was improved as the LED size was reduced. The smallest fabricated gas sensor (active area = 30 × 30 μm²) showed excellent NO₂ sensitivity (ΔR/R₀ = 605% to 1 ppm NO₂) at the optimal operating power (∼184 μW). In addition, the sensor showed a low limit of detection (∼14.9 ppb) and robustness to high humidity conditions, which demonstrate its potential for practical applications in mobile internet of things (IoT) devices.

Modulation of Growth Kinetics of Vacuum-Deposited CsPbBr3 Films for Efficient Light-Emitting Diodes

Because of its excellent optical properties and good stability, all-inorganic halide perovskite CsPbX₃ (X = I, Br, Cl) has been attracting interest for use in light-emitting diodes (LEDs). One challenge is improving the efficacy of the spatial confinement of excitons for higher luminescence efficiency. Here, we present a simple yet very effective strategy to form fine-grain-structured CsPbBr₃ polycrystalline films prepared by thermal co-evaporation. The strategy involves controlling growth kinetics by adjusting the deposition rate, which, along with growth temperature, determines the nucleation rate and therefore the eventual grain structure. A correlation between deposition rate and average grain size was noted except for a very large deposition rate when there were large hillocks, which we attributed to the peculiar growth behavior of PbBr₂ films. The growth conditions that produced a nanoscale grain structure and textured orientations without large hillocks also resulted in the highest luminescence efficiency as we anticipated. With the optimized CsPbBr₃ light emitters, we demonstrate a green-light-emitting (at 524 nm) LED with a maximum current efficiency of 1.07 cd/A and an extremely narrow electroluminescence spectrum of 18 nm, a result that highlights the potential of vacuum-processed CsPbBr₃ films for high-efficiency LEDs.

Orthogonally Polarized, Dual-Wavelength Quantum Wire Network Emitters Embedded in Single Microrod

Semiconductor nanowires are attractive building blocks of optoelectronics due to high efficiency and optical controllability. In particular, the mutual controllability of wavelength and polarization of light is essential for versatile applications such as displays, precise metrology, and bioimaging. We present quantum wire network emitters embedded in a single microrod capable of exhibiting orthogonally polarized dual-wavelength visible light at room temperature. The InGaN/GaN shell layers were grown on a single hexagonal GaN core microrod, spontaneously forming site-selective In-rich InGaN quantum wires on each edge between the nonpolar facets as well as each boundary between the nonpolar and semipolar facets. The orthogonally self-arranged, two sets of six quantum wires formed on the edges and the boundaries showed efficient violet and blue-green color emissions with strong linear polarization parallel and perpendicular to the c-axis at room temperature, respectively. This intriguing emission from a single microrod allows us to mutually manipulate the color and the polarization of light, which would be beneficial for photonic applications with unprecedented controllability and functionality.

P1711The association of multidisciplinary team approach with clinical outcomes in patients with acute myocardial infarction underwent veno-arterial extracorporeal membrane oxygenation

Background

Multidisciplinary team approach is necessary for the management of critically-ill patients. However, limited data are available on the impact of specialized extracorporeal membrane oxygenation (ECMO) team on clinical outcomes in patients with acute myocardial infarction (AMI) complicated by cardiogenic shock.

Objectives

This study aimed to identify whether specialized ECMO team is associated with improved in-hospital mortality in AMI patients underwent venoarterial ECMO.

Methods

A total of 255 AMI patients underwent venoarterial ECMO from May 2004 to July 2018 were enrolled. In January 2014, multidisciplinary ECMO team was founded at our institution. Eligible patients were classified into pre-ECMO team group (n=131) and post-ECMO team group (n=124). The primary outcome was in-hospital mortality.

Results

In-hospital mortality (54.2% vs. 33.9%, p=0.002) and cardiac intensive care unit mortality (45.0% vs. 25.0%, p=0.001) were significantly lower after the implantation of multidisciplinary ECMO team (pre ECMO team vs. post-ECMO team). On binary logistic regression model, the multidisciplinary ECMO team approach was associated with lower risk of in-hospital mortality (odds ratio 0.36, 95% confidence interval 0.19–0.67, p=0.001). Incidence of all-cause mortality (58.3% vs. 35.2%, p<0.001) and rehospitalization due to heart failure (28.2% vs. 6.4%, p=0.001) at 6-months follow-up were also significantly lower in the post-ECMO team group than in the pre-ECMO team group.

Clinical outcomes Variables Total (N=255) Pre-ECMO team (N=131) Post-ECMO team (N=124) P value In-hospital mortality 113 (44.3) 71 (54.2) 42 (33.9) 0.002 Cardiovascular death 90 (35.3) 59 (45.0) 31 (25.0) 0.001 Noncardiovascular death 23 (9.0) 12 (9.2) 11 (8.9) >0.99 Cardiac intensive care unit mortality 106 (41.6) 68 (51.9) 38 (30.6) 0.001 Successful weaning of ECMO 169 (66.3) 75 (57.3) 94 (75.8) 0.002 Data are presented as n (%). Abbreviations: ECMO, extracorporeal membrane oxygenation.

Incidence of death, readmission for HF

Conclusions

The multidisciplinary ECMO team approach was associated with improved clinical outcomes in AMI patients complicated by cardiogenic shock. Our data support that specialized ECMO team is indispensable to improve outcomes in patients with AMI with refractory cardiogenic shock.

P6445Stress hyperglycemia and in-hospital mortality in patients with ST-segment elevation myocardial infarction

Introduction

Stress hyperglycemia is common in acute ill patients and associated with poor clinical outcomes. Some studies demonstrated the association of stress hyperglycemia and poor outcomes in acute MI. However, current results for the impact of stress hyperglycemia on mortality in acute MI who underwent PCI are insufficient.

Purpose

We aimed to evaluate the impact of stress hyperglycemia on clinical outcomes of patients with STEMI underwent primary PCI in large scale multi-center registry.

Methods

From 2007 to 2014, in 1,538 patients of the INTERSTELLAR (Incheon-Bucheon Cohort of Patients Undergoing Primary PCI for Acute ST-Elevation Myocardial Infarction) cohort, 997 patients without diabetes who underwent primary PCI for STEMI were retrospectively analyzed. We defined random glucose more than 200mg/dl at admission without diabetic history or results of HbA1C more than 6.5% as stress hyperglycemia. The primary endpoint was in-hospital all-cause death and the secondary endpoint was all-cause death within 1 year after index PCI.

Results

From 997 nondiabetic cohort population, 117 patients with stress hyperglycemia and 880 patients without stress hyperglycemia were enrolled. Baseline characteristics including age, sex, hypertension, hyperlipidemia, atrial fibrillation, left main disease, and multivessel disease were not significantly different between two groups. However, systolic blood pressure was lower (111.2±39.2 vs. 125.5±28.1, p<0.001) and hypoxic liver injury was frequent (31.0% vs. 20.1%, p=0.007) in stress hyperglycemia. In-hospital and 1-year all-cause mortality were higher in stress hyperglycemia (13.7% vs. 2.7%, p<0.001; 15.4% vs. 3.8%, p<0.001, respectively). However, there is no significant difference in post-discharge mortality rate. Stress hyperglycemia was a significant independent predictor of in-hospital death (adjusted OR: 5.67, 95% CI: 2.40–13.39; p<0.001). Hypotension (defined less than 90mmHg) and left ventricular dysfunction (defined less than 40% of LVEF on echocardiography) were significantly associated with stress hyperglycemia (adjusted OR: 5.72, 95% CI: 3.33–9.82; p<0.001; adjusted OR: 2.38, 95% CI: 1.49–3.82; p<0.001, respectively).

Landmark analysis of all-cause death

Conclusions

In nondiabetic patients who underwent primary PCI for STEMI, stress hyperglycemia is significantly associated with an increased in-hospital all-cause mortality but did not increase post-discharge mortality within 1 year.

Ultrafast carrier dynamics of conformally grown semi-polar (112[combining macron]2) GaN/InGaN multiple quantum well co-axial nanowires on m-axial GaN core nanowires

The growth of semi-polar (112[combining macron]2) GaN/InGaN multiple-quantum-well (MQW) co-axial heterostructure shells around m-axial GaN core nanowires on a Si substrate using MOCVD is reported for the first time. The core GaN nanowire and GaN/InGaN MQW shells are grown in a two-step growth sequence of vapor-liquid-solid and vapor-solid growth modes. The luminescence and carrier dynamics of GaN/InGaN MQW coaxial nanowires are studied by photoluminescence, cathodoluminescence, and low temperature time-resolved photoluminescence (TRPL). The emission is tuned from 430 nm to 590 nm by increasing the InGaN QW thickness. The non-single exponential decay measured by low-temperature TRPL was attributed to the indium fluctuations in the InGaN QW. The ultrafast radiative lifetime was measured from 14 ps to 26 ps with different emission wavelengths at a very high internal quantum efficiency up to 68%. An ultrafast carrier lifetime was assigned to the growth of the InGaN QW on semi-polar (112[combining macron]2) growth facet and the improved carrier collection efficiency due to the radial growth of the GaN/InGaN MQW shells. Such an ultrafast carrier dynamics of NWs provides a meaningful active medium for high speed optoelectronic applications.

Optical properties of GaN nanowires grown on chemical vapor deposited-graphene

Optical properties of GaN nanowires (NWs) grown on chemical vapor deposited-graphene transferred on an amorphous support are reported. The growth temperature was optimized to achieve a high NW density with a perfect selectivity with respect to a SiO₂ surface. The growth temperature window was found to be rather narrow (815°C ± 5°C). Steady-state and time-resolved photoluminescence from GaN NWs grown on graphene was compared with the results for GaN NWs grown on conventional substrates within the same molecular beam epitaxy reactor showing a comparable optical quality for different substrates. Growth at temperatures above 820 °C led to a strong NW density reduction accompanied with a diameter narrowing. This morphology change leads to a spectral blueshift of the donor-bound exciton emission line due to either surface stress or dielectric confinement. Graphene multi-layered micro-domains were explored as a way to arrange GaN NWs in a hollow hexagonal pattern. The NWs grown on these domains show a luminescence spectral linewidth as low as 0.28 meV (close to the set-up resolution limit).

Direct Transfer of Light's Orbital Angular Momentum onto a Nonresonantly Excited Polariton Superfluid

Recently, exciton polaritons in a semiconductor microcavity were found to condense into a coherent ground state much like a Bose-Einstein condensate and a superfluid. They have become a unique testbed for generating and manipulating quantum vortices in a driven-dissipative superfluid. Here, we generate an exciton-polariton condensate with a nonresonant Laguerre-Gaussian optical beam and verify the direct transfer of light's orbital angular momentum to an exciton-polariton quantum fluid. Quantized vortices are found in spite of the large energy relaxation involved in nonresonant pumping. We identified phase singularity, density distribution, and energy eigenstates for the vortex states. Our observations confirm that nonresonant optical Laguerre-Gaussian beam can be used to manipulate chirality, topological charge, and stability of the nonequilibrium quantum fluid. These vortices are quite robust, only sensitive to the orbital angular momentum of light and not other parameters such as energy, intensity, size, or shape of the pump beam. Therefore, optical information can be transferred between the photon and exciton-polariton with ease and the technique is potentially useful to form the controllable network of multiple topological charges even in the presence of spectral randomness in a solid state system.

Primary Segmental Volvulus of Small Intestine: Surgical Perspectives According to Age at Diagnosis

Background: Small intestinal volvulus often occurs with malrotation. However, in some cases, it could develop without any other clinical conditions, and this is called primary segmental volvulus (PSV) of the small intestine. Two types of PSV (early and late neonatal) have been described previously, especially in preterms. Moreover, there were other cases occurring beyond the neonatal period. Methods: The medical records of 14 cases definitively identified as PSV were retrospectively reviewed. The patients were divided into 2 groups according to postnatal age at diagnosis: neonatal group and beyond neonatal group. Then, the 2 groups were compared in terms of clinical features. Results: There were 11 patients in the neonatal group (78.6%) and 3 patients in the beyond neonatal group (21.4%). There were no differences in gestational age, birth weight, and ratio of prematurity. In the neonatal group, the antenatal abnormal sonographic findings were found more frequently and the perforation of the involved segment were relatively common. Meanwhile, the involved segment was confined to the ileum and more commonly associated with mesentery change in the beyond neonatal group. There was no mortality. Conclusion: The 2 clinical types of PSV according to postnatal age at diagnosis show some differences in clinical features. Moreover, PSV should be considered a possible cause of surgical problems beyond the neonatal period.

Electrochemically generated bimetallic reductive mediator Cu1+[Ni2+(CN)4]1- for the degradation of CF4 to ethanol by electro-scrubbing

Remediation of electronic gas CF₄ using commercially available technologies results in another kind of greenhouse gas and corrosive side products. This investigation aimed to develop CF₄ removal at room temperature with formation of useful product by attempting an electrogenerated Cu¹⁺[Ni²⁺(CN)₄]^1- mediator. The initial electrolysis of the bimetallic complex at the anodized Ti cathode demonstrated Cu¹⁺[Ni²⁺(CN)₄]^1- formation, which was confirmed by additional electron spin resonance results. The degradation of CF₄ followed mediated electrochemical reduction by electrogenerated Cu¹⁺[Ni²⁺(CN)₄]^1-. The removal efficiency of CF₄ of 95% was achieved by this electroscrubbing process at room temperature. The spectral results of online and offline Fourier transform infrared analyzer, either in gas or in solution phase, demonstrated that the product formed during the removal of CF₄ by electrogenerated Cu¹⁺[Ni²⁺(CN)₄]^1- by electroscrubbing was ethanol (CH₃CH₂OH), with a small amount of trifluoroethane (CF₃CH₃) intermediate.