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Percutaneous image guided thermal ablation has become a cornerstone of therapy for patients with oligometastatic disease and primary liver malignancies. Evolving from percutaneous ethanol injection (PEI), thermal ablation utilizing radiofrequency ablation (RFA) and microwave ablation (MWA) have become the standard approach in the treatment of isolated lesions that fit within the size criteria for curative intent therapy (typically 3-4cm). With the evolution of more intense thermal ablation, such as MWA, the dramatic increase in both the size of ablation zone and intensity of heat generation have extended the limits of this technique. As a result of these innovations, intra-procedural and post-procedural pain have also significantly increased, requiring either higher levels of intravenous sedation or, in some institutions, general anesthesia. In addition to the increase in therapeutic intensity, the use of intravenous sedation during aggressive ablation procedures carries the risk of over-sedation when the noxious insult (i.e. the ablation) is removed, adding further difficulty to post-procedural recovery and management. Furthermore, high subdiaphragmatic lesions become challenging in this setting due to issues relating to sedation and compliance with breath hold/breathing instructions. Although general anesthesia may mitigate these complications, the added resources associated with providing general anesthesia during ablation is not cost effective and may result in substantial delays in treatment. The reduction of Aerosol Generating Medical Procedures (AGMP), such as intubation due to the COVID-19 Pandemic, must also be taken into consideration. Due to the potential increased risk of infection transmission, alternatives to general anesthesia should be considered when safe and possible. Upper abdominal regional nerve block techniques have been used to manage pain related to trauma, surgery, and cancer; however, blocks of this nature are not well described in the interventional radiology literature. The McGill University group has developed experience in using such blocks as splanchnic, celiac and hepatic hilar nerve blocks to provide peri-procedural pain control [1]. Since incorporating these techniques (along with hydrodissection with tumescent anesthesia), we have also observed in our high volume ablation center a dramatic decrease in the amount of sedatives administered during the procedure, a decrease in patient discomfort during localization and ablation, as well as decreased pain post-procedure. Faster time to discharge and overall reduction in room procedural time serve as added benefits. The purpose of this publication is to outline and illustrate the practical application and use of nerve block/regional anesthesia techniques with respect to percutaneous hepatic thermal ablation.

Summary Aims In the present study, we aimed to determine the muscles that mostly respond to the push-start of the sled. Methods Seven male Korea Winter Olympics elite athletes form the two-man bobsleigh team. Performance was assessed using push-start time. Electromyogram (EMG) activity of the rectus femoris (RF), tibialis anterior (TA), gastrocnemius medialis (GM), and biceps femoris (BF) muscles was recorded during the push-start phases. Results The paired t-test showed that right and left GM activity (P Conclusion This study provides preliminary evidence to suggest that BF muscle activity may represent an effective push-start time to reduce race time in bobsleigh athletes.

This article conducts an exact analysis of a thermal dielectric crack moving in piezoelectric materials. Self-generating thermal and electric loadings by the crack interior are exerted on the crack surfaces as well as various external loadings including a shearing force. Fundamental solutions of the thermal and electro-elastic coupling fields are given by determining a temperature function and a harmonic function with eigenvalues properties due to material properties considered. Analytical expressions are obtained benefiting evaluation of key parameters. Numerical analysis is done and some interesting observations are found. There is a critical crack velocity within and beyond which the electric loading exerts different influences on the thermal flux of crack interior and the thermal stress intensity factor.

Over the last decade, liver transplantation of sicker, older non-hepatitis C cirrhotics with multiple co-morbidities has increased in the United States. We sought to identify an easily applicable set of recipient factors among HCV negative adult transplant recipients associated with significant morbidity and mortality within five years after liver transplantation.We collected national (n = 31,829, 2002-2015) and center-specific data. Coefficients of relevant recipient factors were converted to weighted points and scaled from 0-5. Recipient factors associated with graft failure included: ventilator support (five patients; hazard ratio [HR] 1.59; 95% CI 1.48-1.72); recipient age60 years (three patients; HR 1.29; 95% CI 1.23-1.36); hemodialysis (three patients; HR 1.26; 95% CI 1.16-1.37); diabetes (two patients; HR 1.20; 95% CI 1.14-1.27); or serum creatinine ≥1.5 mg/dl without hemodialysis (two patients; HR 1.15; 95% CI 1.09-1.22).Graft survival within five years based on points (any combination) was 77.2% (0-4), 69.1% (5-8) and 57.9% (8). In recipients with8 points, graft survival was 42% (model for end-stage liver disease [MELD] score25) and 50% (MELD score 25-35) in recipients receiving grafts from donors with a donor risk index1.7. In center-specific data within the first year, subjects with ≥5 points (vs. 0-4) had longer hospitalization (11 vs. 8 days, p 0.01), higher admissions for rehabilitation (12.3% vs. 2.7%, p 0.01), and higher incidence of cardiac disease (14.2% vs. 5.3%, p 0.01) and stage 3 chronic kidney disease (78.6% vs. 39.5%, p = 0.03) within five years.The impact of co-morbidities in an MELD-based organ allocation system need to be reassessed. The proposed clinical tool may be helpful for center-specific assessment of risk of graft failure in non-HCV patients and for discussion regarding relevant morbidity in selected subsets.Over the last decade, liver transplantation of sicker, older patient with multiple co-morbidities has increased. In this study, we show that a set of recipient factors (recipient age60 years, ventilator status, diabetes, hemodialysis and creatinine1.5 mg/dl) can help identify patients that may not do well after transplant. Transplanting sicker organs in patients with certain combinations of these characteristics leads to lower survival.

Background Little published data exist examining causes of hospital readmission following total pancreatectomy with islet autotransplantation (TPIAT). Methods A retrospective analysis was performed of a prospectively collected institutional TPIAT database. Primary outcome was unplanned readmission to the hospital within 30 days from discharge. Reasons and risk factors for readmission as well as islet function were evaluated and compared by univariate and multivariate analysis. Results 83 patients underwent TPIAT from 2006 to 2014. 21 patients (25.3%) were readmitted within 30 days. Gastrointestinal problems (52.4%) and surgical site infection (42.8%) were the most common reasons for readmission. Initial LOS and reoperation were risk factors for early readmission. Patients with delayed gastric emptying (DGE) were three times more likely to get readmitted. In multivariate analysis, patients undergoing pylorus preservation surgery were nine times more likely to be readmitted than the antrectomy group. Conclusion Early readmission after TPIAT is common (one in four patients), underscoring the complexity of this procedure. Early readmission is not detrimental to islet graft function. Patients undergoing pylorus preservation are more likely to get readmitted, perhaps due to increased incidence of delayed gastric emptying. Decision for antrectomy vs. pylorus preservation needs to be individualized.

Summary An open-label, first-in-human phase 1/2 study is being conducted to evaluate the safety and efficacy of pancreatic endoderm cells (PECs) implanted in non-immunoprotective macroencapsulation devices for the treatment of type 1 diabetes. We report an analysis on 1 year of data from the first cohort of 15 patients from a single trial site that received subcutaneous implantation of cell products combined with an immunosuppressive regimen. Implants were well tolerated with no teratoma formation or severe graft-related adverse events. After implantation, patients had increased fasting C-peptide levels and increased glucose-responsive C-peptide levels and developed mixed meal-stimulated C-peptide secretion. There were immunosuppression-related transient increases in circulating regulatory T cells, PD1high T cells, and IL17A+CD4+ T cells. Explanted grafts contained cells with a mature β cell phenotype that were immunoreactive for insulin, islet amyloid polypeptide, and MAFA. These data, and associated findings ( Shapiro et al., 2021 ), are the first reported evidence of meal-regulated insulin secretion by differentiated stem cells in patients.

Liver disease is a major cause of mortality worldwide. Liver transplantation (LT) is the most effective treatment for end stage liver disease. Available resources and social circumstances have led to different ways of implementing LT around the world. The experience with pediatric LT corroborates the hypothesis that a combination of surgical strategies can be beneficial. The goal of this manuscript is to describe the strategies used by LT centers in North America, Europe and Asia and how these strategies can be applied to reduce waitlist mortality and increase access to LT.

BackgroundCombined pancreaticoduodenectomy (PD) and colonic resection may be necessary to achieve an R0 resection of peri-ampullary tumours. The aim of this study was to examine the morbidity and mortality associated with this procedure.MethodsA retrospective cohort study was performed comparing 607 patients who underwent a standard pancreaticoduodenectomy (S-PD) to 28 patients who had a concomitant colon resection and PD (PD-colon) over a 10-year period at an academic centre.ResultsPatients in the PD-colon group were more likely to have received neoadjuvant chemotherapy ± radiation (3/28, 11% versus 14/607, 2%, P = 0.024). Operative time was also longer (530 versus 410min, P < 0.001) and they were more likely to have had portal vein resections (9/28, 32% versus 76/607, 13%, P = 0.007). There was no difference in the intra-operative blood loss, length of stay, or overall complication rates. The PD-colon group had a higher rate of severe post-operative bleeding (4/28, 11% versus 8/607, 1%, P = 0.002). The post-operative mortality rates for the PD-colon and PD groups were 2/28 (7%) and 8/607 (1%), respectively (P = 0.068).ConclusionsPD-colon has an acceptable risk of peri-operative morbidity compared with S-PD in well-selected patients.

Objectives An aberrant right hepatic artery (aRHA) may pose technical and oncologic challenges during pancreaticoduodenectomy (PD) for pancreatic adenocarcinoma (PA) as a result of its proximity to the head of the pancreas. The aim of this study was to assess the impact of an aRHA on resectability, and perioperative and oncologic outcomes after PD for PA. Methods An 11-year retrospective cohort study was conducted. A total of 289 patients with PA scheduled for PD with intent for resection were included in the study. Results Of 289 patients, 249 underwent PD and 40 were found to have unresectable tumours. Incidences of aRHA in the resectable (14.9%) and unresectable (7.5%) groups were similar (P = 0.2); the main reasons for aborting PD were not directly related to the presence of an aRHA. In patients who underwent resection, complications occurred more frequently in the standard PD group (41.5% versus 24.3%; P = 0.04), but there was no difference in rates of positive margin (R1) resection (10.8% versus 16.0%; P = 0.4) or median overall survival (17 months versus 23 months; P = 0.1) between patients with and without an aRHA. Conclusions The presence of an aRHA in patients with PA does not affect resectability. In patients with resectable tumours, the presence of an aRHA does not increase morbidity or R1 resection rates and does not impact on overall survival.

The electrical and optical properties of organic light-emitting devices (OLEDs) with bis(ethylenedithio)-tetrathiafulvalene (BEDT-TTF)-doped 4,7-diphenyl-1,10-phenanthroline (BPhen) electron transport layers (ETLs) were investigated. The current density–voltage characteristics of the OLEDs with BEDT-TTF-doped BPhen ETLs and electron only devices with BEDT-TTF-doped BPhen layers showed that the electrons injected from the cathode were increased by inserting a BEDT-TTF-doped BPhen layer. OLEDs containing BEDT-TTF-doped BPhen layers at a doping concentration of 1 wt.% demonstrated the highest current density and luminance values. Enhancements of the electron injection and luminance as well as a decrease in the operating voltage of the OLEDs were achieved by inserting a BEDT-TTF-doped BPhen layer.

We investigated the effects of swimming and treadmill exercise on the level of nerve growth factor (NGF) protein and neurogenesis in the hippocampus, and cognitive function of adult rats over a period of 8 weeks. We divided 144 male Sprague-Dawley rats into 3 groups: (1) a control group (COG; total n=48, n=8 for each time-point), (2) a swimming exercise group (SEG; total n=48; n=8 for each time-point), and (3) a treadmill exercise group (TEG; total n=48, n=8 for each time-point). The SEG and TEG were made to perform their respective exercise type for 5 days per week over a period of 8 weeks. The level of NGF on the second day, and after the first, second, and fourth weeks increased significantly in the SEG and TEG, compared to the COG (p

Purpose To evaluate the outcome of ophthalmic complications in children with otitis media. Methods The records of children with ophthalmic complications arising from otitis media who presented to the British Columbia Children's Hospital between August 2006 and March 2008 were reviewed retrospectively. Results Of 1,400 patients presenting to the emergency department for otitis media during the study period, 7 with ophthalmic complications were identified (age range, 1-11 years). All patients had abducens nerve palsy on presentation. Other notable ophthalmic complications included papilledema, Horner syndrome, and proptosis. Extracranial and intracranial complications included mastoiditis, petrositis, parapharyngeal abscess, hydrocephalus, epidural abscess, and cerebral venous thrombosis, including cavernous sinus thrombosis in 2. Of the 7 patients, 6 were treated with surgery, including myringotomy and tube placement (6 patients) and mastoidectomy (3 patients). All patients were initially anticoagulated and received intravenous antibiotics. Satisfactory final visual outcomes and stereopsis ranging from 40 to 100 seconds were achieved in all patients. Conclusions Ophthalmic complications of otitis media in children are likely to include abducens palsy. All patients in our series required anticoagulation and intravenous antibiotics. Most required otolaryngologic surgery, but none required strabismus surgery, and all patients had satisfactory visual and ocular motility outcomes.

The effects of electric fields and temperatures on the carrier mobilities in organic layers and at electrode/organic interfaces were investigated by using three-dimensional Monte-Carlo simulation. The mobility variations in the organic layers and at the electrode/organic layer interfaces were described on the basis of the calculated results. The density of deep sites significantly affected the difference in the mobility behavior between the organic layers and the electrode/organic interfaces.

A nano-island array of approximately 7-nm-diameter Zn single crystals embedded in a SiO 2 nanowire was created by using electrospinning and electron-beam irradiation. Bright-field transmission electron microscopy (TEM) images, high-resolution TEM (HRTEM) images, energy dispersive spectroscopy (EDS), and fast-Fourier-transformed electron diffraction patterns showed that Zn nanocrystals were created inside the SiO 2 nanowire. The formation mechanisms of Zn nanoparticles embedded in a SiO 2 nanowire due to the decomposition of ZnO and SiO 2 nanoparticles are described on the basis of the HRTEM images and the EDS profiles.

Objective: To report the incidence of aphakic glaucoma following lensectomy in infants in their first year of life and examine the impact of this diagnosis on visual outcome. Design: Retrospective cohort study. Participants: All patients who had lensectomy for congenital cataract during the first year of life at British Columbia Children's Hospital between 1995 and 2006. Methods: Retrospective review of medical records. Results: Seventy-five eyes of 46 patients (29 bilateral, 17 unilateral) were included. The mean age at lensectomy was 93 days (range, 2–364 days) with a mean follow-up of 77.5 months (range, 36–166 months). Patients with bilateral cataracts had a better visual outcome than those with unilateral cataracts ( p = 0.032). Of the patients with measurable visual acuity (VA), 34 of 45 eyes (75.6%) with bilateral cataracts and only 3 of 16 eyes (18.8%) with unilateral cataract achieved a VA of 20/40 or better. Eighteen of 75 eyes (24%) developed aphakic glaucoma at a mean of 30 months following lensectomy. Nine patients (50%) achieved final vision of 20/40 or better. The development of aphakic glaucoma was not associated with worse visual outcomes ( p = 0.315). The mean intraocular pressure (IOP) at diagnosis was 28.6 ± 5.9 mm Hg and mean final IOP was 14.1 ± 3.0 mm Hg, a significant reduction ( p > 0.0001). Fifteen of 18 eyes with aphakic glaucoma (83.3%) required surgical intervention to achieve IOP control. Conclusions: Children with aphakic glaucoma may have good visual outcomes if it is recognized early and managed appropriately. A significant proportion of patients required surgical intervention to control IOP.

ZnO thin films were deposited on n-Si substrates by using plasma-assisted molecular beam epitaxy. Plane-view zero-loss energy filtered transmission electron microscopy (TEM) images showed that the grain boundaries between large and small grains changed from the curve to the straight shape during ZnO grain growth. The [0 0 0 1]-tilt grain boundary of as-grown ZnO thin films changed from the zigzag facet planes into the symmetric tilt grain boundary through the asymmetric tilt grain boundary with periodic { 0 1 1 ¯ 0 } / { 3 5 8 ¯ 0 } flat planes. Such an atomic structural variation of grain boundary changes from curved grain boundaries to flat shape was due to decrease of total boundary energy during grain growth. The atomic structural variations of the [0 0 0 1]-tilt grain boundaries during ZnO grain growth occurred by thermal treatments are described on the basis of the TEM images.

ZnO nanocrystals embedded in an amorphous Zn 2 x Si 1− x O 2 layer inserted between a ZnO thin film and a p-Si (1 0 0) substrate were formed by magnetron sputtering and thermal annealing. High-resolution transmission electron microscopy (HRTEM) images showed that ZnO nanocrystals were embedded in the Zn 2 x Si 1− x O 2 layer inserted into a ZnO/Si heterostructure. The { 0 1 1 ¯ 0 } planes were observed for the ZnO nanocrystals with a [0 0 0 1] orientation direction, and the { 0 1 1 ¯ 1 } and the {0 0 0 1} planes were observed for the ZnO nanocrystal with a [ 2 1 ¯ 1 ¯ 0 ] orientation direction. The formation of ZnO nanocrystals consisting of the most stable {0 0 0 1} and { 0 1 1 ¯ 1 } facet planes was attributed to atomic rearrangement of Zn and O atoms to reduce the surface energy during the thermal annealing and the cooling processes. The formation mechanisms for the ZnO nanocrystals embedded in an amorphous Zn 2 x Si 1− x O 2 layer inserted into a ZnO/p-Si (1 0 0) heterostructure were described on the basis of the HRTEM images.

Well-aligned GaN nanorods were synthesized on Si substrates to form heterojunctions with potential applications in photovoltaic (PV) cells. Transmission electron microscopy images, selected area electron diffraction pattern images, and photoluminescence spectra showed that the GaN crystalline nanorods were preferentially oriented along the [0 0 0 1] direction and were very well-aligned perpendicular to the Si (1 1 1) substrate. An ultraviolet (UV) PV cell based on GaN nanorod/n-Si heterojunctions was fabricated, and current–voltage curves under an illumination with UV light exhibited obvious PV effect with a power conversion efficiency of about 1%.

A correlation between composition, microstructure, and magnetic properties of sputter-deposited CoFeSiB alloy films has been studied. Various analytical tools and micromagnetic models were employed to understand the details of microstructural evolution and magnetic reversal processes, respectively. The CoFeSiB alloy film shows significantly different microstructure and magnetic properties depend on the Co concentration. When the Co concentration is below 75 at.%, the alloy has an amorphous phase exhibiting magnetic softness with negative remanence. Meanwhile, beyond 75 at.%, the structure consists of nanocrystals precipitated in the amorphous matrix, which becomes magnetically hard with positive remanence as well as antiferromagnetic exchange coupling.

An X-ray diffraction pattern (XRD) showed that GaN nanorods grown on Si(111) substrates were preferentially oriented along the [0001] direction. The transmission electron microscopy (TEM) images showed that the side facet planes of the tip region for the GaN nanorods consisted of {1100} and {1102} planes. The disordered nuclei of the GaN nanorods produced a two-dimensional thin-film layer near the GaN/Si(111) interfacial region. The relation between the microstructural properties and the geometry factors of the tip region for GaN nanorods formed on Si(111) substrates is described on the basis of the XRD and TEM results.

X-ray diffraction (XRD) patterns revealed that the as-grown and annealed Al-doped ZnO (AZO) films grown on the n-Si (1 0 0) substrates were polycrystalline. Transmission electron microscopy (TEM) images showed that bright-contrast regions existed in the grain boundary, and high-resolution TEM (HRTEM) images showed that the bright-contrast regions with an amorphous phase were embedded in the ZnO grains. While the surface roughness of the AZO film annealed at 800 °C became smoother, those of the AZO films annealed at 900 and 1000 °C became rougher. XRD patterns, TEM images, selected-area electron diffraction patterns, HRTEM images, and atomic force microscopy (AFM) images showed that the crystallinity in the AZO thin films grown on the n-Si (1 0 0) substrates was enhanced resulting from the release in the strain energy for the AZO thin films due to thermal annealing at 800 °C. XRD patterns and AFM images show that the crystallinity of the AZO thin films annealed at 1000 °C deteriorated due to the formation of the amorphous phase in the ZnO thin films.

The luminescence properties of zinc oxide (ZnO) nanocrystals grown from solution are reported. The ZnO nanocrystals were characterized by scanning electron microscopy, X-ray diffraction, cathodo- and photoluminescence (PL) spectroscopy. The ZnO nanocrystals have the same regular cone form with the average sizes of 100–500 nm. Apart from the near-band-edge emission around 381 nm and a weak yellow–orange band around 560–580 nm at 300 K, the PL spectra of the as-prepared ZnO nanocrystals under high-power laser excitation also showed a strong defect-induced violet emission peak in the range of 400 nm. The violet band intensity exhibits superlinear excitation power dependence while the UV emission intensity is saturated at high excitation laser power. With temperature raising the violet peak redshifts and its intensity increases displaying unconventional negative thermal quenching behavior, whereas intensity of the UV and yellow–orange bands decreases. The origin of the observed emission bands is discussed.

Nitrogen-doped p-type ZnSe, p-type ZnSySe1−y, and p-type Zn1−xMgxSySe1−y epilayers were grown on n-type GaAs (1 0 0) substrates by molecular beam epitaxy. Photoluminescence (PL) spectra for the p-type ZnSe and the lattice-matched p-type ZnS0.06Se0.94, and p-type Zn0.92Mg0.08S0.12Se0.88 epilayers showed a deep acceptor bound exciton emission and a donor–acceptor pair emission. Temperature-dependent PL measurements were carried out to determine the activation energies of these states. The activation energies of the acceptor-bound excitons and the donor–acceptor pairs were determined to be 40 and 65 meV in the p-type ZnSe epilayer, 20 and 45 meV in the p-type ZnS0.06Se0.94, and 45 and 43 meV in the p-type Zn0.92Mg0.08S0.12Se0.88 epilayers.

X-ray diffraction patterns, scanning electron microscopy images, and transmission electron microscopy (TEM) images showed that one-dimensional GaN nanorods grown on Si (1 1 1) substarates by using hydride vapor phase epitaxy had crystalline wurzite structures and were preferentially oriented along the [0 0 0 1] direction. The high-resolution TEM (HRTEM) images showed that the side facet planes of the tip region for the GaN nanorods consisted of {1¯ 1 0 0}, {1¯ 1 0 2}, and {1¯ 1 0 3} planes. The structural properties of the GaN nanorods were significantly affected by the gas-mixing and the substrate temperatures in the final growth zone.

Mn+-implanted and annealed Si1−xGex thin films grown on p-Si (100) substrates were formed with the goal of producing (Si1−xGex)1−yMny with a high ferromagnetic transition temperature ( T c ) . The double-crystal X-ray rocking curves and transmission electron microscopy images showed that the Mn-implanted and annealed Si1−xGex thin films were single crystalline. The magnetization curves as functions of the magnetic field clearly showed that ferromagnetism existed in the Mn + -implanted and annealed Si1−xGex thin films, and the magnetization curves as functions of the temperature showed that the T c value was above 300 K. These results indicate that the formed (Si1−xGex)1−yMny thin films hold promise for potential applications in Si-based spintronic devices operating at room temperature.

Scanning electron microscopy (SEM) images, transmission electron microscopy (TEM) images, and selected-area electron diffraction (SAED) patterns showed that vertically well aligned GaN nanorods with c-axis-oriented crystalline wurzite structures were grown on Si(1 1 1) substrates by using hydride vapor phase epitaxy. The high-resolution TEM (HRTEM) images showed that the crystallized GaN nanorods contained very few defects and that they were consisted of { 1 ¯ 1 0 0 } , {0 0 0 1}, and { { 1 ¯ 1 0 N } } facets. The formation mechanisms for the GaN nanorods grown on Si(1 1 1) substrates are described on the basis of the SEM, TEM, SAED pattern, and HRTEM results.

X-ray diffraction (XRD) patterns, field-emission scanning electron microscopy (FESEM) images, transmission electron microscopy (TEM) images, and selected area electron diffraction pattern (SADP) images showed that one-dimensional GaN nanorods with c -axis-oriented single-crystalline wurzite structures were grown on Si (1 1 1) substrates by using improved hydride vapor phase epitaxy. The high-resolution TEM (HRTEM) images showed that the crystallized GaN nanorods contained very few defects. The atomic arrangements for the GaN nanorods grown on the Si (1 1 1) substrates are described on the basis of the XRD, the TEM, the SADP, and the HRTEM results.

The influence of the presence of a double emitting layer (DEL) consisting of 4,4′-Bis(carbazol-9-yl)biphenyl (CBP) and 4,4′-Bis(2,2-diphenyl-ethen-1-yl)diphenyl (DPVBi) acting as electron and hole trapping layers in the organic light-emitting devices (OLEDs) was studied. While the luminance efficiency of the OLEDs with a DEL was very stable, regardless of variations in the applied voltage, that of the OLEDs with a CBP or a DPVBi emitting layer varied with the applied voltage. The rate of decrease is smaller than the single emitting layer, about 30%. The dominant peak corresponding to the CBP layer, in the electroluminescence spectrum for the OLEDs with a DEL appeared at 451 nm, which is in the deep-blue region. The Commission Internationale de l'Eclairage chromaticity coordinates of the OLEDs with a DEL at 11 V were (0.150, 0.137), indicative of a deep, stabilized blue color. These results indicate that luminance efficiency-stabilized blue OLEDs can be fabricated using a CBP/DPVBi DEL acting as electron and hole trapping layers.

The electrical and the optical properties of organic light-emitting devices (OLEDs), with and without multiple heterostructures consisting of N, N-bis-(1-naphthyl)-N, N-diphenyl-1,1-biphenyl-4,4-diamine (NPB)/5,6,11,12-tetraphenylnaphthacene (rubrene) acting as a hole transport layer (HTL), were investigated. The OLEDs with 3 periods of NPB/mixed rubrene:NPB multiple heterostructures acting as an HTL showed the highest luminances and efficiencies. While the electroluminescence (EL) peak corresponding to the rubrene layer did not appear for the OLEDs with 3 periods of NPB/mixed rubrene:NPB multiple heterostructures, only the EL peak related to the tris (8-hydroxyquinoline) aluminum layer was observed. The Commission Internationale de l’Eclairage chromaticity coordinates of the OLEDs with 3 periods of NPB/mixed rubrene:NPB multiple heterostructures at 14 V were (0.321, 0.531), indicative of a deep stabilized green color.

The degradation behaviors of the electrical and the optical properties of organic light-emitting devices (OLEDs) fabricated with an emitting layer (EML) doped with or without a wide-bandgap-impurity were investigated. The OLEDs with a wide-bandgap-doped Alq 3 EML were more stable than those with an undoped Alq 3 EML. The existence of the doped wide-bandgap-impurity in the EML decreased the trap-charge density in the EML, resulting in an increase in the number of electrons in the Alq 3 EML. That increases in the number of electron in the Alq 3 EML for the OLEDs with a wide-bandgap-impurity decreased the staying time of the holes in the Alq 3 EML, resulting in an enhanced lifetime for the OLEDs. These results indicate that OLEDs with a wide-bandgap-impurity-doped EML hold promise for potential applications in long-lifetime OLED displays.

The light extraction efficiencies of organic light emitting diodes (OLEDs) utilizing various kinds of porous alumina films with different pore diameters were investigated. The OLEDs with the porous alumina film deposited on the glass surface were fabricated to improve their light extraction efficiency. The porous alumina film was fabricated by using a two step anodizing electrochemical procedure. The current densities as functions of the applied voltage do not significantly change, regardless of the existence and the magnitude of the pore diameter in the porous alumina film. The luminance efficiency of the OLEDs increased with increasing pore diameter. The luminance efficiency of the OLEDs utilizing the porous alumina film with a pore diameter of 70 nm was enhanced approximately 9% in comparison with that of the OLEDs without the porous alumina film. These results indicate that highly efficient OLEDs can be fabricated using a porous alumina film with an optimum pore diameter.

The photo and cathodoluminescence of zinc oxide (ZnO) filled opal arrays, as well as ZnO nanocrystals prepared by a chemical deposition method were investigated. The photoluminescence (PL) from the arrays was studied using angular resolution. The PL spectra of the filled opal exhibited a dip corresponding to the array’s photonic band gap. ZnO nanocrystals embedded in the opal matrix demonstrated quenched excitonic emission while the opal matrix showed enhanced emission. This effect is explained by an energy transfer from ZnO nanocrystals to the opal matrix.

Dependence of the magnetic properties on the Mn/In flux ration in multiple stacked self-assembled (In 1− x Mn x )As quantum dots (QDs) was investigated. Transmission electron microscopy images showed that crystalline (In 0.84 Mn 0.16 )As QDs with symmetric single-domain particles were formed on GaAs substrates. Magnetic force microscopy (MFM) images showed that the density of the (In 1− x Mn x )As QDs decreased with increasing Mn/In flux ratio, and the magnetization curves as functions of the magnetic field at 5 K depicted that the magnetization of the (In 1− x Mn x )As QDs increased. Near-field scanning optical spectroscopy spectra for the (In 0.84 Mn 0.16 )As stacked QDs showed the interband transitions from the ground electronic subband to the ground heavy-hole band, indicative of the semiconductor phase of the QDs. These results indicate that magnetic properties of (In 1− x Mn x )As QDs are affected by the Mn/In flux ratio.

CdTe thin films were grown on GaAs (1 0 0) substrates by using molecular beam epitaxy at various temperatures. The bright-field transmission electron microscopy (TEM) images and the high-resolution TEM (HRTEM) images showed that the crystallinity of CdTe epilayers grown on GaAs substrates was improved by increasing the substrate temperature. The result of selected-area electron diffraction pattern (SADP) showed that the orientation of the grown CdTe thin films was the (1 0 0) orientation. The lattice constant the strain, and the stress of the CdTe thin film grown on the GaAs substrate were determined from the SADP result. Based on the SADP and HRTEM results, a possible atomic arrangement for the CdTe/GaAs heterostructure is presented.

ZnO nanocrystals capped with an organic dye Rhodamine 6G (Rh6G) were investigated by photoluminescence (PL) and cathodoluminescence (CL) techniques. PL and CL spectra showed a remarkable decrease in visible emission intensity after ZnO nanocrystals were capped with Rh6G, indicating that dangling bonds and defect states existing at the surface of ZnO nanocrystals were significantly passivated. Rh6G on the ZnO surface exhibited a monomer-like emission, and the intensity and the position of the emission were dependent on the dye concentration.

The electrical and the optical properties of organic light-emitting diodes (OLEDs) fabricated utilizing nickel-oxide (NiO) buffer layers between the anodes and the hole transport layers were investigated. The NiO layer was formed by using a thermally evaporated nickel thin film and a subsequent oxidation process. The tunneling holes in the OLED were increased due to the existence of the NiO layer between the anode and the hole transport layer, resulting in enhanced efficiency for the OLED. These results indicate that OLEDs with NiO buffer layers hold promise for potential applications in highly-efficient flat-panel displays.

Ti/Ge 2 Sb 2 Te 5 /Ti thin films deposited by a sputtering method on SiO 2 /Si substrates were annealed at 400 °C in N 2 atmosphere and characterized by using transmission electron microscopy (TEM) and Auger electron spectroscopy (AES) in order to investigate the inter-diffusion of the Ti/Ge 2 Sb 2 Te 5 /Ti system due to annealing. The TEM and AES results showed that the interface between the Ti and the Ge 2 Sb 2 Te 5 layers was unstable and Ti atoms were incorporated into the Ge 2 Sb 2 Te 5 thin film upon annealing. The Te and Sb atoms of the Ge 2 Sb 2 Te 5 layer diffused into the Ti layer. The intermixing layers between the Ge 2 Sb 2 Te 5 layer and two Ti layers were formed. These results indicate that the microstructural properties of the Ti/Ge 2 Sb 2 Te 5 /Ti systems can be degraded by the postgrowth thermal annealing.

Scanning electron microscopy (SEM), Fourier transform infrared (FTIR) transmission, and Hall effect measurements were performed to investigate the structural, optical, and electrical properties of as-grown and in situ-annealed Hg0.7Cd0.3Te epilayers grown on CdTe buffer layers by using molecular beam epitaxy. After the Hg0.7Cd0.3Te epilayers had been annealed in a Hg-cell flux atmosphere, the SEM images showed that the surface morphologies of the Hg0.7Cd0.3Te thin films were mirror-like with no indication of pinholes or defects, and the FTIR spectra showed that the transmission intensities had increased in comparison to that of the as-grown Hg0.7Cd0.3Te epilayer. Hall-effect measurements showed that n-Hg0.7Cd0.3Te epilayers were converted to p-Hg0.7Cd0.3Te epilayers. These results indicate that the surface, optical, and electrical properties of the Hg1 − xCdxTe epilayers are improved by annealing and that as-grown n-Hg1 − xCdxTe epilayers can be converted to p-Hg1 − xCdxTe epilayers by in situ annealing.

The optical properties and the deep levels in bulk Si 1− x Mn x formed by using an implantation and annealing method were investigated. Transmission electron microscopy, X-ray diffraction, and Hall-effect measurements showed that the annealed bulk Si 1− x Mn x samples were p-type crystalline semiconductors. The photoluminescence spectra for the annealed bulk Si 1− x Mn x material showed luminescence peaks corresponding to excitons bound to neutral acceptors and related to dislocations due to the existence of Mn impurities. Deep-level transient spectroscopy results for the annealed bulk Si 1− x Mn x showed deep levels related to the interstitial and substitutial sites of the Mn + ions. These results can help improve understanding of the optical properties and the deep levels in annealed bulk Si 1− x Mn x material.

ZnO active layers on ZnO buffer layers were grown at various O2/O2 + Ar flow-rate ratios by using radio-frequency magnetron sputtering. Atomic force microscopy images showed that the surface roughnesses of the ZnO active layers grown on ZnO buffer layers decreased with decreasing O2 atmosphere, indicative of an improvement in the ZnO surfaces. The type of the ZnO active layer was n-type, and the resistivity of the layer increased with increasing O2 atmosphere. Photoluminescence spectra from the ZnO active layers grown on the ZnO buffer layers showed dominant peaks corresponding to local levels in the ZnO energy gap resulting from oxygen vacancies or interstitial zinc vacancies, and the peak positions changed significantly with the O2/O2 + Ar flow rate. These results can help improve understanding of the dependences of the surface and the optical properties on the O2/O2 + Ar ratio for ZnO thin films grown on ZnO buffer layers.

We consider two equations for the filling factor estimation of infiltrated zinc oxide (ZnO) in silica (SiO2) opal and gallium nitride (GaN) in ZnO opal. The first equation is based on the effective medium approximation, while the second one—on Maxwell–Garnett approximation. The comparison between two filling factors shows that both equations can be equally used for the estimation of the quantity of infiltrated nanoparticles inside opal photonic crystal.

We have studied growth of self-assembled CdTe quantum dots (QDs) grown on various thicknesses of ZnTe buffer layer by using molecular beam epitaxy (MBE) and atomic layer epitaxy (ALE). The excitonic peak corresponding to the interband transitions from the ground electronic subband to the ground heavy-hole band (E1−HH1) in the CdTe/ZnTe QDs shifted to a lower energy with increasing thickness of the ZnTe buffer layer. The results of the atomic force microscopy (AFM) images showed that the size of the CdTe/ZnTe QDs increases with increasing thickness of the ZnTe buffer layer. The activation energy of the electrons confined in the CdTe/ZnTe QDs, as obtained from the temperature-dependent PL spectra, increases with increasing thickness of the ZnTe buffer layer. These results can help improve our understanding of the effect of the ZnTe buffer layer on the structural and the optical properties of CdTe/ZnTe QDs.

We have studied structural and optical properties of self-assembled Cd 0.6 Zn 0.4 Te/ZnTe quantum dots (QDs) grown on Si(1 0 0) substrates by using molecular beam epitaxy. X-ray diffraction patterns indicated that the ZnTe buffer layers grown on the Si substrates were hetero-epitaxial films with the (1 0 0) orientation. The atomic force microscopy images showed that Cd 0.6 Zn 0.4 Te/ZnTe QDs were formed on Si(1 0 0) substrates. The photoluminescence spectra at 32 K showed the dominant excitonic peaks corresponding to the interband from the ground-state electronic sub-band to the ground-state heavy-hole band in the Cd 0.6 Zn 0.4 Te/ZnTe QDs. The present results can help to improve the understanding of the structural and interband transition properties in Cd 0.6 Zn 0.4 Te/ZnTe QDs grown on Si(1 0 0) substrates.

(Ga1−xMnx)N thin films grown on GaN buffer layers by using molecular beam epitaxy were investigated with the goal of producing diluted magnetic semiconductors (DMSs) with band-edge exciton transitions for applications in optomagnetic devices. The magnetization curve as a function of the magnetic field at 5 K indicated that ferromagnetism existed in the (Ga1−xMnx)N thin films, and the magnetization curve as a function of the temperature showed that the ferromagnetic transition temperature of the (Ga1−xMnx)N thin film was above room temperature. Photoluminescence and photoluminescence excitation spectra showed that band-edge exciton transitions in (Ga1−xMnx)N thin films appeared. These results indicate that the (Ga1−xMnx)N DMSs with a magnetic single phase hold promise for potential applications in spin optoelectronic devices in the blue region of the spectrum.

Hexagonal MnAs thin films were grown on GaAs (1 0 0) substrates by using molecular beam epitaxy. The magnetization curve as a function of the magnetic field at 5 K showed that the MnAs thin films were ferromagnetic, and the magnetization curve as a function of the temperature revealed that the ferromagnetic transition temperature was as high as 318 K. The selected-area electron-diffraction pattern (SADP) and the high-resolution transmission electron microscopy (HRTEM) measurements on the MnAs/GaAs heterostructure showed that the hexagonal MnAs layer was grown pseudomorphically on the GaAs substrate. Based on the SADP and HRTEM results, a possible crystal structure for the MnAs/GaAs heterostructure is presented.

Atomic force microscopy (AFM) measurements were carried out to investigate the formation of CdTe quantum dots (QDs) grown on GaAs substrates by using molecular beam epitaxy. The AFM images showed that uniform CdTe QDs were formed on GaAs substrates due to the large lattice mismatch between the CdTe QDs and the GaAs substrate. The size and the density of the CdTe QDs were varied by changing the thickness and the substrate temperature. The formation behavior for the CdTe QDs on the GaAs substrate is in reasonable agreement with a Volmer–Weber (V–W) growth mode. The size and the density of the CdTe QDs grown on the GaAs substrate by using the V–W growth mode are compared with those of the CdTe QDs grown on the ZnTe buffer layer by using the Stranski–Krastanow mode. The present results can help improve understanding of the formation and the structural properties of CdTe QDs directly grown on GaAs substrates.

Reflection high-energy electron diffraction, atomic force microscopy, transmission electron microscopy, and double-crystal X-ray curves showed that high-quality InAs quantum dot (QD) arrays inserted into GaAs barriers were embedded in an Al0.3Ga0.7As/GaAs heterostructure. The temperature-dependent photoluminescence (PL) spectra of the InAs/GaAs QDs showed that the exciton peak corresponding interband transition from the ground electronic subband to the ground heavy-hole subband (E1–HH1) was dominantly observed and that the peak position and the full width at half maximum corresponding to the interband transitions of the PL spectrum were dependent on the temperature. The activation energy of the electrons confined in the InAs/GaAs QDs was 115 meV. The electronic subband energy and the energy wave function of the Al0.3Ga0.7As/GaAs heterostructures were calculated by using a self-consistent method. The electronic subband energies in the InAs/GaAs QDs were calculated by using a three-dimensional spatial plane wave method, and the value of the calculated (E1–HH1) transition in the InAs/GaAs QDs was in reasonable agreement with that obtained from the PL measurement.

Photoluminescence (PL) and transmittance measurements were carried out to investigate the optical properties of ZnO nanoparticles inserted into ultraviolet (UV) opal. The ZnO nanoparticles were grown in the voids between face-centered cubic packed silica spheres by using a chemical deposition. The PL spectra showed a decrease in the band edge emission and an enhancement of the deep-level emission from the ZnO nanoparticles embedded in the UV opal. The PL intensity enhancement in the green spectral region might be attributed to the Purcell effect. The infiltration of ZnO nanoparticles inside an artificial opal can be used to select the spectral band and to increase the emission efficiency of ZnO nanoparticles.