Descending aortic translocation for left aortic arch with right descending aorta and coarctation of the aorta.

Left aortic arch with right descending aorta associated with coarctation of the aorta is a rare congenital cardiac anomaly. Conventional aortic arch repair in this condition may cause airway compression by the abnormally coursing descending aorta. We present the case of a neonate with this anomaly who underwent successful descending aortic translocation to prevent postoperative left main bronchial stenosis.

Core-Shell Tunnel Junction Nanowire White-Light-Emitting Diode.

We have demonstrated a new class of phosphor-free white LEDs with the use of tunnel junction structure in nonpolar core-shell InGaN nanowires. It is confirmed that the tunnel junction based nanowire LEDs can eliminate the use of the resistive p-GaN:Mg contact layer, leading to significantly enhanced hole injection and dramatically reduced voltage loss. The nonpolar core-shell nanowire heterostructure showed the enhanced carrier injection efficiency through the widened shell n-GaN contact area. The TEM analysis verified that the core-shell Al tunnel junction layers were uniformly grown on nonpolar surfaces of the GaN wurtzite crystal nanowire structure. We have also showed the monolithic integration of multiple-color emission on a single chip by using the multiple-stacked tunnel junction core-shell nanowire heterostructure. Compared to the conventional film based quantum well LEDs, the demonstrated nonpolar core-shell tunnel junction nanowire LEDs will be a very promising candidate for future solid-state lighting applications as well as phosphor-free white LEDs.

Utility of three-dimensional printed heart models for education on complex congenital heart diseases.

OBJECTIVE: The objective of this study was to evaluate the feasibility and effects of education on complex congenital heart diseases using patient-specific three-dimensional printed heart models. METHODS: Three-dimensional printed heart models were created using computed tomography data obtained from 11 patients with complex congenital heart disease. Fourteen kinds of heart models, encompassing nine kinds of complex congenital heart disease were printed. Using these models, a series of educational hands-on seminars, led by an experienced paediatric cardiac surgeon and a paediatric cardiologist, were conducted for medical personnel who were involved in the care of congenital heart disease patients. Contents of the seminars included anatomy, three-dimensional structure, pathophysiology, and surgery for each diagnosis. Likert-type (10-point scale) questionnaires were used before and after each seminar to evaluate the effects of education. RESULTS: Between November 2019 and June 2020, a total of 16 sessions of hands-on seminar were conducted. The total number of questionnaire responses was 75. Overall, participants reported subjective improvement in understanding anatomy (4.8 ± 2.1 versus 8.4 ± 1.1, p < 0.001), three-dimensional structure (4.6 ± 2.2 versus 8.9 ± 1.0, p < 0.001), pathophysiology (4.8 ± 2.2 versus 8.5 ± 1.0, p < 0.001), and surgery (4.9 ± 2.3 versus 8.8 ± 0.9, p < 0.001) of the congenital heart disease investigated. CONCLUSIONS: The utilisation of three-dimensional printed heart models for education on complex congenital heart disease was feasible and improved medical personnel's understanding of complex congenital heart disease. This education tool may be an effective alternative to conventional education tools for complex congenital heart disease.

Tricuspid atresia with absent pulmonary valve and intact ventricular septum: successful bidirectional cavopulmonary anastomosis with complete exclusion of the right ventricle.

Tricuspid atresia with absent pulmonary valve and intact ventricular septum is an extremely rare cardiac malformation, historically associated with a poor prognosis. Only a few cases with successful surgical palliation have been reported in the literature. We present the case of an 8-month-old infant with this malformation who underwent successful bidirectional cavopulmonary anastomosis with complete exclusion of the right ventricle.

Surface Characterizations of Railway Electrical Wires Coated with Anti-Icing Mixtures of Ethylene Glycol or Glycerol with Tap Water.

Icing of railway contact wires in the cold climates of the USA, Canada, China, Japan, and South Korea can cause significant problems and delays in the operation schedules of electric-powered trains and subway cars. As anti-icing methods, manual de-icing, contact-wire thermal running, resistive-wire-heating de-icing, and chemical de-icing have all been explored and tested. Among them, environmentally friendly chemical de-icing based on the same concept as that of automobileengine antifreezer can be practically effective for application to contact wires at railcar depots. In the present study, the railway contact wires are coated with anti-icing mixtures of ethylene glycol/tap water and glycerol/tap water at various ratios (v/v %) as well as with tap water alone, at temperatures of -30 and -40 °C in a deep freezer. The morphological change on the wire surfaces is observed under optical microscopy. The surface-contact angles are measured to examine the surface difference between uncoated and coated railway contact-wire fragments. Conclusively, the fragments coated with 40/60 and 60/40 (v/v %) ratios of ethylene glycol or glycerol with tap water, as compared with the uncoated fragments, are shown to have been effectively de-iced. The surface-characterizations data thus indicate that mixtures of glycerol or ethylene glycol with tap water can be practical de-icing agents for application to railway contact wires.

Impact of Al Pre-Deposition Layer on Crystalline Quality of GaN Grown on Si(111) Substrates.

The effects of Al metal pre-deposition under different conditions on GaN grown on Si(111) substrates by metal-organic chemical vapor deposition (MOCVD) have been investigated. Al pre-deposition improves surface morphology and crystal quality of GaN grown on Si. The surface morphology of Al pre-deposition layer, AlN, and GaN vary depending on Al pre-deposition temperature. With the increase of Al pre-deposition temperature, Al cluster size is observed to increase in the Al predeposition layer due to increased lateral mobility of Al atoms. The Al pre-deposition carried out at about 750 °C enables to grow pit-free GaN layer on Si(111) substrate.

Successful mitral valve repair for isolated mitral regurgitation in a child with Williams syndrome.

Williams syndrome is a genetic disorder associated with various cardiovascular abnormalities, most commonly supravalvar aortic stenosis and peripheral pulmonary stenosis. However, isolated severe mitral regurgitation necessitating surgical intervention is extremely rare. Here, we present the case of a 14-year-old child with Williams syndrome and isolated severe mitral regurgitation who underwent successful mitral valve repair.

Formation of spherical-shaped GaN and InN quantum dots on curved SiN/Si surface.

This paper reports the formation of GaN and InN quantum dots (QDs) with symmetric spherical shapes, grown on SiN/Si(111). Spherical QDs are grown by modulating initial growth behavior via gallium and indium droplets functioning as nucleation sites for QDs. Field-emission scanning electron microscope (FE-SEM) images show that GaN and InN QDs are formed on curved SiN/Si(111) instead of on a flat surface similar to balls on a latex mattress. This is considerably different from the structural properties of In(Ga)As QDs grown on GaAs or InP. In addition, considering the shape of the other III-V semiconductor QDs, the QDs in this study are very close to the ideal shape of zero-dimensional nanostructures. Transmission-electron microscope images show the formation of symmetric GaN and InN QDs with a round shape, agreeing well with the FE-SEM results. Compared to other III-V semiconductor QDs, the unique structural properties of Si-based GaN and InN QDs are strongly related to the modulation in the initial nucleation characteristics due to the presence of droplets, the degree of lattice mismatch between GaN or InN and SiN/Si(111), and the melt-back etching phenomenon.

Repair of interrupted aortic arch using autologous pulmonary artery tissue.

There are several options for the repair of interrupted aortic arch. Direct anastomosis may cause several problems including anastomotic site stenosis, left main bronchus compression, and acute-angled aortic arch. Interposition of a prosthetic graft has no growth potential. We present a case of 34-month-old child with interrupted aortic arch, which was repaired using a pulmonary autograft tube.

Yellow-red light-emitting diodes using periodic Ga-flow interruption during deposition of InGaN well.

We report a possible way to extend the emission wavelength of InyGa1-yN/InxGa1-xN quantum-well (QW) light-emitting diodes (LEDs) to the yellow-red spectral range with little degradation of the radiative efficiency. The InyGa1-yN well with high indium (In) content (HI-InyGa1-yN) was realized by periodic Ga-flow interruption (Ga-FI). The In contents of the HI-InyGa1-yN well and the InxGa1-xN barrier were changed to manipulate the emission wavelength of the LEDs. An In0.34Ga0.66N/In0.1Ga0.9N-QW LED, grown by continuous growth mode (C-LED), was prepared as a reference. The photoluminescence (PL) wavelengths of the HI-InyGa1-yN/InxGa1-xN QW LEDs were changed from 556 to 597 nm. The PL intensity of the HI-InyGa1-yN/InxGa1-xN LED with a peak wavelength of 563 nm was 2.7 times stronger than that of the C-LED (λ = 565 nm). The luminescence intensity for the HI-InyGa1-yN/InxGa1-xN QW LED emitting at 597 nm was stronger than those of the other LED samples with shorter wavelengths. Considering the previous works on degradation in crystal quality and increase in the quantum-confined Stark effect with increasing In content in InGaN, the approach in this work is very promising for yellow-red InGaN LEDs.

Topochemical polymerization of dumbbell-shaped diacetylene monomers: relationship between chemical structure, molecular packing structure, and gelation property.

Herein, we have synthesized novel photopolymerizable dumbbell-shaped diacetylene liquid crystal (LC) monomers by locating a diacetylene dicarboxylic acid group at the center and chemically connecting swallow-tails, such as hydrophobic alkyl chains (abbreviated as AT3DI) and amphiphilic biphenyl mesogens (abbreviated as BP3DI), with bisamide groups. Major phase transitions of dumbbell-shaped diacetylene monomers were identified using differential scanning calorimetry (DSC), polarized optical microscopy (POM), and Fourier transform infrared spectroscopy (FT IR). Molecular packing structures were studied based on structure-sensitive wide-angle X-ray diffraction (WAXD) and small-angle X-ray scattering (SAXS) analyses. Mainly, due to nanophase separations and strong intermolecular hydrogen bonding, AT3DI formed a low-ordered lamellar LC phase at room temperature. BP3DI self-assembled into highly-ordered crystal phases (K1 and K2) at lower temperatures below a low-ordered lamellar LC phase, in which BP3DI were intercalated with each other to compensate the mutual volume differences. From the photopolymerization of AT3DI and BP3DI, it was realized that the topochemical reactions of dumbbell-shaped diacetylene monomers were closely related to their chemical structures as well as molecular packing structures.

Optical characteristics of InGaN/GaN light-emitting diodes depending on wafer bowing controlled by laser-treated grid patterns.

We evaluated the effects of grid patterns (GPs) realized on 2-inch sapphire substrates by simple laser treatment on the device characteristics of InGaN/GaN light-emitting diodes (LEDs). The degrees of wafer bowing for the LEDs with distances between the GPs of 1 (GP1-LED), 2 (GP2-LED), and 3 mm (GP3-LED) were 100.05, 100.43, and 101.59 µm, respectively, which are significantly improved compared to that (108.06 µm) of a conventional LED (C-LED) without GPs. Consequently, a blue-shift of the emission wavelength for the GP-LEDs was observed compared to the C-LED via alleviation of the quantum-confined stark effect. A comparative study of the fluorescence microscopy images of the C-LED and GP2-LED samples showed a significant reduction of threading dislocations as a result of the GPs. In the electroluminescence mapping results for the entire 2-inch region, the standard deviations of the emission wavelengths were 1.64, 1.49, and 2.55 nm for the GP1-LED, GP2-LED, and GP3-LED samples, respectively, which are smaller than that of the C-LED (2.66 nm). In addition, the average output power of the GP2-LED was 8.5% higher than that of the C-LED.

Influences of Si-doped graded short-period superlattice on green InGaN/GaN light-emitting diodes.

We report significant improvement in optical and electrical properties of green InGaN/GaN light-emitting diodes (LEDs) by using Si-doped graded short-period InGaN/GaN superlattice (SiGSL) formed by so called indium-conversion technique. For comparison, a conventional LED without the superlattice (C-LED) and a LED with undoped graded superlattice (unGSL-LED) were prepared, respectively. The photoluminescence (PL) intensity of the SiGSL-LED was increased more than 3 times at room temperature (RT) as compared to C-LED. The PL intensity ratios of RT to 10K for the C-LED, unGSL-LED, and SiGSL-LED were measured to be 25, 40.9, and 47.5%, respectively. The difference in carrier lifetimes between 10K and RT for the SiGSL-LED is relatively small compared to that of the C-LED, which is consistent with the variation in PL intensity. The output power of a transistor-outline type SiGSL-LED was increased more than 2 times higher than that of the C-LED.

Single nanowire light-emitting diodes using uniaxial and coaxial InGaN/GaN multiple quantum wells synthesized by metalorganic chemical vapor deposition.

We report the controlled synthesis of InGaN/GaN multiple quantum well (MQW) uniaxial (c-plane) and coaxial (m-plane) nanowire (NW) heterostructures by metalorganic chemical vapor deposition. Two kinds of heterostructure NW light-emitting diodes (LEDs) have been fabricated: (1) 10 pairs of InGaN/GaN MQW layers in the c-plane on the top of n-GaN NWs where Mg-doped p-GaN NW is axially grown (2) p-GaN/10 pairs of InGaN/GaN shell structure were surrounded by n-GaN core. Here, we discuss a comparative analysis based on the m-plane and the c-plane oriented InGaN/GaN MQW NW arrays. High-resolution transmission electron microscopy studies revealed that the barrier and the well structures of MQW were observed to be substantially clear with regular intervals while the interface regions were extremely sharp. The c-plane and m-plane oriented MQW single NW was utilized for the parallel assembly fabrication of the LEDs via a focused ion beam. The polarization induced effects on the c-plane and m-plane oriented MQW NWs were precisely compared via power dependence electroluminescence. The electrical properties of m-plane NWs exhibited superior characteristics than that of c-plane NWs owing to the absence of piezoelectric polarization fields. According to this study, high-quality m-plane coaxial NWs can be utilized for the realization of high-brightness LEDs.

Coaxial In(x)Ga(1-x)N/GaN multiple quantum well nanowire arrays on Si(111) substrate for high-performance light-emitting diodes.

We report the growth of high-quality nonpolar (m-plane) and semipolar (r-plane) multiple quantum well (MQW) nanowires (NWs) for high internal quantum efficiency light emitting diodes (LEDs) without polarization. Highly aligned and uniform In(x)Ga(1-x)N/GaN MQW layers are grown coaxially on the {1-100} sidewalls of hexagonal c-axis n-GaN NWs on Si(111) substrates by a pulsed flow metal-organic chemical vapor deposition (MOCVD) technique. The photoluminescence (PL) measurements reveal that the wavelength and intensity of an MQW structure with various pairs (2-20) are very stable and possess composition-dependent emission ranging from 369 to 600 nm. The cathodoluminescence (CL) spectrum of individual In(x)Ga(1-x)N/GaN MQW NW is dominated by band-edge emission at 369 and 440 nm with a relatively homogeneous profile of parallel alignment. High-resolution transmission electron microscopy (HR-TEM) studies of coaxial InxGa1-xN/GaN MQW NWs measured along the [0001] and [2-1-10] zone axes reveal that the grown NWs are uniform with six nonpolar m-plane facets without any dislocations and stacking faults. The p-GaN/In(x)Ga(1-x)N/GaN MQW/n-GaN NW coaxial LEDs show a current rectification with a sharp onset voltage at 2.65 V in the forward bias. The linear enhancement of power output could be attributed to the elimination of piezoelectric fields in the In(x)Ga(1-x)N/GaN MQW active region. The superior performance of coaxial NW LEDs is observed in comparison with that of thin film LEDs. Overall, the feasibility of obtaining low defect and strain free m-plane coaxial NWs using pulsed MOCVD can be utilized for the realization of high-power LEDs without an efficiency droop. These kinds of coaxial NWs are viable high surface area MQW structures which can be used to enhance the efficiency of LEDs.

Long-term Outcomes of Polytetrafluoroethylene Bicuspid Pulmonary Valve Replacement.

BACKGROUND: In 2016 we reported promising midterm outcomes of bicuspid pulmonary valve replacement using 0.1-mm polytetrafluoroethylene (PTFE) membrane. This follow-up study analyzes long-term outcomes and risk factors for reintervention and structural valve deterioration (SVD). METHODS: We performed a retrospective review of the original 119 patients who underwent PTFE bicuspid pulmonary valve replacement. Median patient age was 16.9 years (range, 0.4-57.1). Reintervention was defined as any surgical or percutaneous catheter procedure on the PTFE valve. SVD was defined as development of a peak pressure gradient ≥ 50 mm Hg or at least a moderate amount of pulmonary regurgitation on follow-up echocardiography. RESULTS: The median follow-up duration was 9.5 years. The survival rate was 96.5% at 5 and 10 years, with 2 early and 2 late mortalities. Freedom from reintervention was 90.0% at 5 years and 63.3% at 10 years. Freedom from SVD was 92.8% at 5 years and 51.1% at 10 years, with regurgitation the predominant mode (64.6%). Freedom from both reintervention and SVD at 5 and 10 years were 89.1% and 49.5%, respectively. Multivariable analysis identified smaller valve diameter (hazard ratio, 0.82; P < .001) and more than trivial pulmonary regurgitation at discharge (hazard ratio, 5.81; P < .001) as risk factors for reintervention or SVD. CONCLUSIONS: Long-term results of the PTFE bicuspid pulmonary valve replacement were acceptable. However, improvements may be needed to reduce technical error and improve durability. Smaller valve diameter and more than trivial pulmonary regurgitation at discharge were risk factors for reintervention or SVD, warranting careful follow-up for timely reintervention.

Patent ductus arteriosus management in very-low-birth-weight prematurity: a place for an early operation?

OBJECTIVES: The goal was to evaluate neonatal outcomes based on treatment strategies and time points for haemodynamically significant patent ductus arteriosus (hsPDA) in very-low-birth-weight preterm infants, with a particular focus on surgical closure. METHODS: This retrospective study included very-low-birth-weight infants born between 2014 and 2021 who received active treatment for hsPDA. Neonatal outcomes were compared between (i) primary surgical closure versus primary ibuprofen; (ii) early (<14th post-natal day) versus late primary surgical closure (≥14th post-natal day); and (iii) primary versus secondary surgical closure after ibuprofen failure. Further analysis using 1:1 propensity score matching was performed. Logistic regression was conducted to analyse the risk factors for post-ligation cardiac syndrome (PLCS) and/or acute kidney injury (AKI). RESULTS: A total of 145 infants with hsPDA underwent active treatment for closure. The in-hospital death rate and the incidence of severe bronchopulmonary dysplasia (BPD) were similar between the primary surgical closure group and the primary ibuprofen group in a 1:1 matched analysis. Severe BPD was significantly higher in the late surgical closure group than in the early primary surgical closure group with 1:1 propensity score matching (72.7% vs 40.9%, P=0.033). The secondary surgical closure group showed the mildest clinical condition; however, the probability of PLCS/AKI was highest (38.6%) compared to the early (15.2%) or the late primary surgical group (28.1%, P<0.001), especially in extremely premature infants (gestational age < 28 weeks). CONCLUSIONS: Surgical patent ductus arteriosus closure is not inferior to pharmacologic treatment. Considering the harmful effect of a prolonged patent ductus arteriosus shunt exposure, a timely decision and timely efforts should be made to minimize the risk of severe BPD and PLCS/AKI after surgical closure.

Low-Leakage Current Core-Shell AlGaN Nanorod LED Device Operating in the Ultraviolet-B Band.

Despite the considerable potential of AlGaN-based ultraviolet-B light-emitting diodes (UV-B LEDs) in various applications such as phototherapy, UV curing, plant growth, and analytical technology, their development is still ongoing due to low luminescence efficiency. In this study, we introduced a novel epitaxial growth mechanism to effectively control the height and thickness of AlGaN multiple wells (MWs) on AlGaN nanorod structures using horizontal reactor-based metal-organic chemical vapor deposition (MOCVD). By adjusting the H2 carrier gas flow rate, we could control the growth boundary layer's thickness, successfully separating the AlGaN well and p-AlGaN layer from the substrate. Cathodoluminescence (CL) measurements confirmed the stability of the core-shell AlGaN quantum wells as a highly stable nonpolarized structure, with the wavelength peak remaining almost unchanged under various injection currents. Furthermore, transmission electron microscopy (TEM) provided clear evidence of differentiation, highlighting the distinct formation of the 275 nm AlGaN core and the 295 nm AlGaN shell structure. The developed AlGaN MW structure, characterized by these rectification features, not only demonstrated a significantly improved electroluminescence (EL) peak intensity but also exhibited a much lower leakage current compared to the conventional core-shell AlGaN structure. The newly proposed growth mechanism and advanced nonpolarized core-shell AlGaN structure are expected to serve as excellent alternatives for substantially enhancing the efficiency of the next generation of high-efficiency UV LEDs.

Primary or Delayed Repair for Complete Atrioventricular Septal Defect, Tetralogy of Fallot, and Ventricular Septal Defect: Relationship to Country Economic Status.

OBJECTIVE: Primary repair in the first six months of life is routine for tetralogy of Fallot, complete atrioventricular septal defect, and ventricular septal defect in high-income countries. The objective of this analysis was to understand the utilization and outcomes of palliative and reparative procedures in high versus middle-income countries. METHODS: The World Database of Pediatric and Congenital Heart Surgery identified patients who underwent surgery for: tetralogy of Fallot, complete atrioventricular septal defect, and ventricular septal defect. Patients were categorized as undergoing primary repair, repair after prior palliation, or palliation only. Country economic status was categorized as lower middle, upper middle, and high, defined by the World Bank. Multiple logistic regression models were utilized to identify independent predictors of hospital mortality. RESULTS: Economic categories included high (n = 571, 5.3%), upper middle (n = 5,342, 50%), and lower middle (n = 4,793, 49.7%). The proportion of patients and median age with primary repair were: tetralogy of Fallot, 88.6%, 17.7 months; complete atrioventricular septal defect, 83.4%, 7.7 months; and ventricular septal defect, 97.1%, ten months. Age at repair was younger in high income countries (P < .0001). Overall mortality after repair was lowest in high income countries. Risk factors for hospital mortality included prematurity, genetic syndromes, and urgent or emergent operations (all P < .05). CONCLUSIONS: Primary repair was selected in >90% of patients, but definitive repair was delayed in lower and upper middle income countries compared with high-income countries. Repair after prior palliation versus primary repair was not a risk factor for hospital mortality. Initial palliation continues to have a small but important role in the management of these three specific congenital heart defects.