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Excess emission has been observed from velvet cathodes with total emission times >150 ns. In this diode experiment, we produce a sub-relativistic electron beam with the ability to consistently change γ from 1.2 to 1.5 and β = 0.5–0.75. Electron emission in this particular diode geometry requires electric fields >40 kV/cm. The current increases at steady rates >0.05 A/ns after the head of the pulse, indicating an expansion of the emission surface and reduction in the effective AK gap. Small transients of excess emission (or arcs) are consistently observed for current pulses exceeding 150 ns. The excess emission results in beam loaded levels ≥ 10 kV on the diode voltage. The effects described here are compounded as diode voltage is increased. The principal objective of these experiments is to quantify electric field emission thresholds, current ramps, excess emission delays, effective beam loading, and impedance collapse. [ABSTRACT FROM AUTHOR]

There is an emerging body of evidence showing that young patients, post haematopoietic stem cell transplantation (HSCT), can develop skeletal changes that mimic an osteochondrodysplasia process. The key discriminator is that these children have had otherwise normal growth and skeletal development before the therapeutic intervention (HSCT), typically for a haematological malignancy. Herein we present that case of a boy who underwent HSCT for Haemophagocytic Lymphohistiocytosis (HLH) aged 2 years. Following Intervention with HSCT this boy's growth has severely decelerated (stature less than 1st centile matched for age) and he has developed a spondyloepiphyseal dysplasia. [ABSTRACT FROM AUTHOR]

The purpose of this study is to explore the effect of additive manufacturing (AM) process variables on the grain structure of Fe-6Si, a soft-magnetic alloy used in electrical machine and grid applications. Samples were fabricated with laser engineered net shaping (LENS) with varying inter-pass timing and numbers of unidirectional passes. The results show that the grain structure was affected by both solidification and solid-state grain growth mechanisms. A model of the LENS process suggests that, although shorter inter-pass times encourage greater nucleation of new grains and therefore grain refinement during solidification, these conditions also help maintain high solid-state temperatures that allow for grain boundary motion to keep pace with the build rate. Grains formed under these conditions may span multiple layers, and the high-temperature gradient promotes directional growth. This new understanding of these microstructure evolution mechanisms will aid in using process conditions to control the competition between solidification and solid-state grain growth to create grain structures that may not be possible with conventional processing. [ABSTRACT FROM AUTHOR]

A spatially resolved air-wedge shearing interferometer and shadowgraph diagnostic provides measurements of electron density with a resolution of ∼ 40 μ m. A ∼ 100-ns-long, monoenergetic electron bunch at 19.8 MeV and a current of 1.4 kA (8.5 × 10 14 e −) heats 100- μ m-thick aluminum (Al) foils in a 1-mm-spot to T e ∼ 1 eV. A 5-ns-long, ∼ 60 mJ, frequency doubled Nd:YAG laser probes the dense Al plasma. Electron densities up to 10 20 cm − 3 are resolved; the maximum resolvable density is limited by opacity, transmission, and spatial fringe density achievable with the detector. This diagnostic provides measurements of the total phase shift, transmission, and electron density. Several measurements at different time slices provide the ability to determine the velocity of the leading edge of the shadowgraph and compare it to the motion of different density shells. These measurements are also compared to radiation hydrodynamics simulations. A rough quantitative agreement is shown between the hydro simulations and the measurements; there are differences in the exact density distributions. [ABSTRACT FROM AUTHOR]

The article describes the case of a 38-year old white male with congenitally missing maxillary lateral incisors who received lithium disilicate crowns with custom milled zirconia abutments instead of anodized custom milled titaniuim abutment. Factors to restoring implants include tissue thickness and implant angulation. It differentiates zirconia prostheses from lithium disilicate in terms of material translucency and notes the esthetic effect of the thickness of restorative material.

Successfully combating the COVID-19 pandemic depends on mass vaccination with suitable vaccines to achieve herd immunity. Here, we describe COVI-VAC, the only live attenuated severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) vaccine currently in clinical development. COVI-VAC was developed by recoding a segment of the viral spike protein with synonymous suboptimal codon pairs (codon-pair deoptimization), thereby introducing 283 silent (point) mutations. In addition, the furin cleavage site within the spike protein was deleted from the viral genome for added safety of the vaccine strain. Except for the furin cleavage site deletion, the COVI-VAC and parental SARS-CoV-2 amino acid sequences are identical, ensuring that all viral proteins can engage with the host immune system of vaccine recipients. COVI-VAC was temperature sensitive in vitro yet grew robustly (>107 plaque forming units/mL) at the permissive temperature. Tissue viral loads were consistently lower, lung pathology milder, and weight loss reduced in Syrian golden hamsters (Mesocricetus auratus) vaccinated intranasally with COVI-VAC compared to those inoculated with wild-type (WT) virus. COVI-VAC inoculation generated spike IgG antibody levels and plaque reduction neutralization titers similar to those in hamsters inoculated with WT virus. Upon challenge with WT virus, COVI-VAC vaccination reduced lung challenge viral titers, resulted in undetectable virus in the brain, and protected hamsters from almost all SARS-CoV-2-associated weight loss. Highly attenuated COVI-VAC is protective at a single intranasal dose in a relevant in vivo model. This, coupled with its large-scale manufacturing potential, supports its potential use in mass vaccination programs. [ABSTRACT FROM AUTHOR]

Solidification characteristics in the meltpool drive the process-microstructure relationship which helps dictate the material properties of as-built parts in additive manufacturing; therefore, being able to accurately and quickly simulate the size, shape, and solidification characteristics in the melt pool is of great interest to the field. This study investigates various important physical phenomena (dynamic material properties, fluid-flow, radiation and vaporization) which can either be included or neglected in a continuum finite volume model (FVM) and their effect on the solidification conditions. Additionally, since the simplest form of such a model (conduction only) has an analytic solution which is much faster, its viability is also considered. Since the inclusion of some of these physical phenomena will inherently change the net energy input as well as the amount of energy needed to achieve melting of a control volume, each set of included phenomena had an effective absorption efficiency which was calibrated to closely match the dimensions of the melt pool to that of the ground truth data. The ground truth data for this study was defined to be the output of the FVM which included all the physical phenomena (OF). This study then goes on to compare the effects on solidification conditions each of these calibrated models has. It was found that most of the change in solidification conditions comes from the inclusion of latent heat. A posterior correlation factor (PCF) is then introduced to enable an analytic model to predict similar solidification conditions to OF model. [ABSTRACT FROM AUTHOR]

Spatially and temporally resolved visible absorption spectroscopy is performed on sodium D-lines present as surface contaminants on an expanded dense aluminum plasma plume. An 80-ns FWHM, intense, relativistic electron beam deposits 5.4 J into a 100-μm-thick Al foil, which isochorically heats and subsequently hydrodynamically expands the material through the warm dense matter state and into a classical-like plasma state, with a coupling parameter of approximately 0.2 and a degeneracy parameter of approximately 270. The Na contamination, carried along with the expanding plume, shows saturated absorption features in the dense Al continuum for λ > 450 nm. X-ray photoelectron spectroscopy and laser-induced breakdown spectroscopy confirm Na is a surface contaminant with an atomic concentration of ∼ 0.1 % when interrogating identical foil samples. A spectroscopic-quality radiation transport model is used to post-process 2D hydrodynamic simulations to interpret the plasma conditions based on the measured Na 3p-3s doublet line profiles. A sodium number density of 3 × 10 15 cm−3 best matches the experimental spectra, which originate from a dense surface plasma with n e = 3.0 ± 0.8 × 10 18 cm−3. [ABSTRACT FROM AUTHOR]

Genome-wide studies often exclude family members, even though they are a valuable source of information. We identified parent–offspring pairs, siblings and couples in the UK Biobank and implemented a family-based DNA-derived heritability method to capture additional genetic effects and multiple sources of environmental influence on neuroticism and years of education. Compared to estimates from unrelated individuals, total heritability increased from 10 to 27% and from 17 to 56% for neuroticism and education respectively by including family-based genetic effects. We detected no family environmental influences on neuroticism. The couple similarity variance component explained 35% of the variation in years of education, probably reflecting assortative mating. Overall, our genetic and environmental estimates closely replicate previous findings from an independent sample. However, more research is required to dissect contributions to the additional heritability by rare and structural genetic effects, assortative mating, and residual environmental confounding. The latter is especially relevant for years of education, a highly socially contingent variable, for which our heritability estimate is at the upper end of twin estimates in the literature. Family-based genetic effects could be harnessed to improve polygenic prediction. [ABSTRACT FROM AUTHOR]

Currently, influenza vaccine manufacturers need to produce 1–5 x 107 PFU of each vaccine strain to fill one dose of the current live-attenuated-influenza-vaccine (LAIV). To make a single dose of inactivated vaccine (15 ug of each hemagglutinin), the equivalent of 1010 PFU of each vaccine strains need to be grown. This high dose requirement is a major drawback for manufacturing as well as rapidly sourcing sufficient doses during a pandemic. Using our computer-aided vaccine platform Synthetic Attenuated Virus Engineering (SAVE), we created a vaccine candidate against pandemic H1N1 A/CA/07/2009 (CodaVax-H1N1) with robust efficacy in mice and ferrets, and is protective at a much lower dose than the current LAIV. CodaVax-H1N1 is currently in Phase I/II clinical trials. The hemagglutinin (HA) and neuraminidase (NA) gene segments of A/California/07/2009 (H1N1) (CA07) were "de-optimized" and a LAIV was generated ex silico using DNA synthesis. In DBA/2 mice, vaccination at a very low dose (100 or approximately 1 PFU) with CodaVax-H1N1 prevented disease after lethal challenge with wild-type H1N1. In BALB/c mice, as little as 103 PFU was protective against lethal challenge with mouse-adapted H1N1. In ferrets, CodaVax-H1N1 was more potent compared to currently licensed LAIV and still effective at a low dose of 103 PFU at preventing replication of challenge virus. [ABSTRACT FROM AUTHOR]

We measure the time-resolved photoluminescence characteristics of a novel type of lithographically patterned quantum dot fabricated by electron beam lithography, wet chemical etching, and overgrowth of the barrier layers by metalorganic chemical vapor deposition.We find that the quantum dot (QD) photoluminescence exhibits a bi-exponential decay that we explain in terms of the fast capture of carriers by defect states followed by a slower radiative relaxation process. We also perform a systematic investigation of the rise time and decay time as a function of the QD density, size, and temperature. These measurements indicate that the carrier capture process in this type of QD is limited by carrier drift within the GaAs barrier material. [ABSTRACT FROM AUTHOR]

We present an analysis of the physics of intersubband transitions in a patterned inverse quantum dot (IQD) array. Numerical techniques for computing the oscillator strength for intersubband transitions are outlined along with the selection and sum rules. It is demonstrated that the polarization dependence of intersubband absorption can be controlled through appropriate design of the IQD array geometry. [ABSTRACT FROM AUTHOR]

We present a detailed analytical study of the effect of nanopore lattice geometry, material parameters, and temperature on the density of states and intraband energy gaps in an ordered nanopore array diode laser. An improved fabrication process is proposed to increase the peak gain achievable in the nanopore laser by a factor of 3 based on the simulation results. [ABSTRACT FROM AUTHOR]

The upper cladding and residual guide thickness have been varied to develop an optimal asymmetric cladding ridge waveguide geometry for use in photonic integrated circuits (PICs). Measured values of the intrinsic loss, threshold current, and lateral modal characteristics allowed the determination of the geometry that simultaneously achieved good active device performance and a strong lateral index step. The bend loss was found by fabricating curved-waveguide y-branch lasers. These characteristics are important for fabricating low-loss routing structures in PICS. This experimental work analyzed an asymmetric cladding ridge waveguide for use with photonic integrated circuits; however, the method presented here generally can be used for the experimental optimization of ridge waveguide lasers. [ABSTRACT FROM AUTHOR]

We critically test the capabilities of the effective-medium approximation (EMA) and alloy models to describe multilayer samples with gradual interfaces by analyzing spectroscopic ellipsometric (SE) data of two AlGaAs samples grown expressly for this purpose. The dielectric functions [variant_greek_epsilon] of the interfaces are calculated in the EMA and alloy models, and the interfaces themselves simulated either as a single layer of Al0.5Ga0.5As or a stack of layers of AlxGa1-xAs with x increasing or decreasing between 0.1 and 0.9 in increments of 0.1. The EMA essentially fails completely for either interface representation. For the alloy model the stepwise-graded representation is significantly better, not only simulating the data more accurately but also yielding thicknesses in essential agreement with those obtained by cross-sectional transmission electron microscopy. The results highlight the types of errors that are encountered with the different models, and show that the analysis of SE data can provide information about these interfaces. [ABSTRACT FROM AUTHOR]

The reflectivity of surface-etched distributed Bragg reflector (DBR) laser gratings, suitable for incorporation in photonic integrated circuits, is determined from a series of samples having varied grating etch depths. The effective index step and DBR scattering loss are used to characterize the relationship between the physical structure and associated optical characteristics of asymmetric cladding surface-etched lasers at 850 nm. These results enable the fabrication of frequency-selective DBR gratings with a predetermined grating index step and reflectivity. [ABSTRACT FROM AUTHOR]

This paper describes the rationale for the development of three Internet-enabled prototype information systems and presents a case study for each system. The prototypes are applications developed to support the e-supply ambitions of three companies and their supply-chain partners by allowing production information created at the prime tier to be made accessible to first-, second- and third-tier suppliers. Each prototype consists of a series of information systems' trials, and the impact of these trials on supply-chain performance is established using a range of indicators aggregated in the form of a scorecard. The scorecard for each prototype is compared with an equivalent scorecard used to establish the performance of the original supply-chain configuration. The prototypes reveal a potential opportunity for using the Internet to share supply-chain information and demonstrate how timely access to accurate production (or demand) information can enable second- and third-tier suppliers to align their manufacturing activities with final product assembly at the prime tier, improve build-to-order capability and make efficiency gains in terms of inventory reduction and lead-time compression. In one highlighted trial, the pipeline inventory and supply-chain cycle time were reduced from 53 days to less than 7 days. [ABSTRACT FROM AUTHOR]

Control of interchain separation enables the optical properties of polymer thin films to be altered. We present a thin film preparation technique that increases the free volume fraction in spin coated polymer thin films resulting in reduced interchain interaction. The polaron yield, measured using photoinduced absorption, was significantly reduced as a direct result of the increased interchain separation, leading to a higher value for the measured photoluminescence efficiency. Impedance spectroscopy showed an increase in permittivity, probably due to greater polarizability. Increases approaching one order of magnitude were observed for direct current hole conductivity and mobility values. Space charge limited conduction analysis suggests a narrowing of the highest occupied molecular orbital band tail on treatment resulting in reduced trapping. Single layer light emitting devices prepared using this technique were found to be significantly brighter and to have longer operating lifetimes. © 2004 American Institute of Physics. [ABSTRACT FROM AUTHOR]

Alternating current (ac) and direct current (dc) conductivities have been measured in polymer-nanotube composite thin films. This was carried out for a range of concentrations of multiwall nanotubes in two polymer hosts, poly(m-phenylenevinylene-co-2,5-dioctyloxyp-phenylenevinylene) (PmPV) and polyvinylalcohol (PVA). In all cases the dc conductivity σ[sub DC] was ohmic in the voltage range studied. In general the ac conductivity displayed two distinct regions, a frequency independent region of magnitude σ[sub 0] at low frequency and a frequency dependent region at higher frequency. Both σ[sub DC] and σ[sub 0] followed a percolation scaling law of the form σ∝(p-p[sub c])[sup t] with p[sub c] = 0.055% by mass and t = 1.36. This extrapolates to a conductivity of 1 × 10[sup -3] S/m for 100% nanotube content. Such a low value reflects the presence of a thick polymer coating, resulting in poor electrical connection between tubes. This leads to the suggestion that charge transport is controlled by fluctuation induced tunneling. In the high frequency regime the conductivity increases with frequency according to an approximate power law with exponent s ≈ 0.92, indicative of hopping transport. The onset of this frequency independent conductivity scales with mass fraction for the PmPV composite due to the variation of correlation length with nanotube content. This behavior is discussed in terms of a biased random walk in three dimensions. In addition ac universality is demonstrated by the construction of a mastercurve. [ABSTRACT FROM AUTHOR]

We have studied the effects of using a composite fabricated from carbon nanotubes and a host polymer, poly(m-phenylene-vinylene-co-2,5-dioctyloxy-p-phenylene-vinylene) (PmPV), as an electron-transport layer in organic light-emitting diodes. Double layer devices using this composite as an electron-transport layer, triple layer devices with a composite electron-transport layer, and poly(9-vinylcarbazole) as a hole-transport layer, as well as poly(2,5-dimethoxy-1,4phenylene-vinylene-2-methoxy- 5(2′-ethylhexyloxy)-1,4-phenylene-vinylene (M3EH-PPV) single layer devices were prepared. Current–voltage–luminance and electroluminescent spectral measurements were performed using six different nanotube powder to polymer mass ratios (0%, 2%, 4%, 8%, 16%, and 32%) for all device structures studied. dc transport and photoluminescence behavior of the polymer-nanotube composite were also investigated. Although a potential barrier is introduced at the M3EH-PPV/composite interface, a significant increase in efficiency was observed using the composite. The best efficiency was obtained for those devices with an electron-transport layer of mass ratio 8%. In addition, on doping with nanotubes, electron conductivity in the composite increased by over 4 orders of magnitude with little quenching of photoluminescence. © 2000 American Institute of Physics. [ABSTRACT FROM AUTHOR]

Photoluminescence (PL) and photoluminescence excitation (PLE) spectroscopies have been carried out at 6 K on the ∼1540 nm [sup 4]I[sub 13/2]-[sup 4]I[sub 15/2] emissions of Er[sup 3+] in Er-implanted and annealed GaN. These studies revealed the existence of multiple Er[sup 3+] centers and associated PL spectra in Er-implanted GaN films grown by metalorganic chemical vapor deposition, hydride vapor phase epitaxy, and molecular beam epitaxy. The results demonstrate that the multiple Er[sup 3+]PL centers and below-gap defect-related absorption bands by which they are selectively excited are universal features of Er-implanted GaN grown by different techniques. It is suggested that implantation-induced defects common to all the GaN samples are responsible for the Er site distortions that give rise to the distinctive, selectively excited Er[sup 3+]PL spectra. The investigations of selectively excited Er[sup 3+]PL and PLE spectra have also been extended to Er-implanted samples of Mg-doped GaN grown by various techniques. In each of these samples, the so-called violet-pumped Er[sup 3+]PL band and its associated broad violet PLE band are significantly enhanced relative to the PL and PLE of the other selectively excited Er[sup 3+]PL centers. More importantly, the violet-pumped Er[sup 3+]PL spectrum dominates the above-gap excited Er[sup 3+]PL spectrum of Er-implanted Mg-doped GaN, whereas it was unobservable under above-gap excitation in Er-implanted undoped GaN. These results confirm the hypothesis that appropriate codopants can increase the efficiency of trap-mediated above-gap excitation of Er[sup 3+] emission in Er-implanted GaN. © 2001 American Institute of Physics. [ABSTRACT FROM AUTHOR]

Despite high rates of co-occurring tobacco use and anxiety among persons living with HIV, evidence-based interventions for these individuals are limited. An existing cognitive-behavioral treatment protocol for smoking cessation and anxiety (Norton, P. J., & Barrera, T. L. (2012). Transdiagnostic versus diagnosis-specific CBT for anxiety disorders: A preliminary randomized controlled noninferiority trial. Depression and Anxiety, 29(10), 874-882. https://doi.org/10.1002/da.21974) was modified to address transdiagnostic constructs, such as anxiety sensitivity, distress tolerance, and depressive symptomatology (Labbe, A. K., Wilner, J. G., Kosiba, J. D., Gonzalez, A., Smits, J. A., Zvolensky, M. J., ... O'Cleirigh, C. (2017). Demonstration of an Integrated Treatment for Smoking Cessation and Anxiety Symptoms in People with HIV: A Clinical Case Study. Cognitive and Behavioral Practice, 24(2), 200-214. https://doi.org/10.1016/j.cbpra.2016.03.009). This study examines the feasibility and acceptability of the intervention as determined from qualitative data from structured exit interviews from 10 participants who completed treatment. Results demonstrated that participants were very motivated to quit smoking and enrolled in the program for health-related reasons and to be able to quit. Participants found nearly all the treatment components to be useful for reaching their smoking cessation goal and in managing emotional dysregulation. Last, all participants stated that they would strongly recommend the treatment program. This qualitative study provides initial evidence for the feasibility and acceptability of a modified smoking cessation treatment protocol for HIV+ individuals with anxiety and emotional dysregulation. Future research will focus on evaluating the efficacy of the protocol in a full-scale randomized controlled trial, as well as working to collect qualitative data from participants who discontinue treatment to better understand reasons for treatment attrition. [ABSTRACT FROM AUTHOR]

Presents a study which focuses on the amorphization mechanism operative in Al0.6Ga0.4As/GaAs structures. Examination of the damage produced by the ion implantations; Consistency of the recovered structure; Basis of structures; Indication of results.

Presents a study which examined the ion implantation damage in AlxGa1 - xAs. Information on the X-ray diffraction and channeling-Rutherford backscattering spectrometry employed in this study; Preparation of the samples used in this study; Results of this study.

Presents a study aimed at monitoring the thickness of GaAs growth by surface photoabsorption in metalorganic chemical vapor deposition. Information on metalorganic chemical vapor deposition; Explanation of the experiment used in the study; Results of and discussion on the experiment.

Provides information on a study that determined the influence of interface type on the accumulation of damage and ion mixing in Al[subx]Ga[sub1-x]As/GaAs heterostructures by using a combination of Rutherford backscattering spectrometry and transmission electron microscopy. Experimental procedure; Experimental results and discussion; Conclusions.

Provides information on a study that examined luminescence properties of GaN layers grown by metalorganic chemical vapor deposition on sapphire substrates with GaN/AIN double buffer layers or GaN single buffer layers. Methodology of the study; Results and discussion on the study.

Presents a study that investigated the effect of electron beam exposure on the room-temperature electroluminescence spectra on a p-n junction GaN light emitting diode. Background on GaN based III-V nitride semiconductor system; Analysis of the change in electroluminescence spectral features; Discussion on the origin of each electroluminescence band.

Deals with a study which examined the effect of deposition temperature of a-Si:H films deposited by the de glow discharge technique on the structural and electrical properties of the laser-crystallized films. Experimental procedures; Results and discussion; Conclusion.

Presents information on a study which described the deposition of hydrogenated amorphous silicon films on molybdenum by direct current glow discharge. Factors in building a polysilicon structure where the effects of aluminum in silicon could be eliminated; Structural and electrical properties of the polysilicon films; Experimental details; Results and discussion; Conclusions.

Deals with a study that investigated the ion implantation damage in Al[sub0.6]Ga[sub0.4]As/gallium arsenide heterostructures. Factor to which the difference in the damage states at the bottom and top interfaces is attributed; Method used to determine the depth dependence and nature of the damage produced by the ion implantation; Reason for the greater degree of damage produced at the bottom interface.

Presents a study that examined the gain characteristics for a series of five separate confinement heterostructure indium compound strained-layer quantum well lasers. Use of indium compound strained-layer quantum well heterostructure laser diodes; Dependence of emission wavelength on cavity length for five different quantum well compositions.

Presents a study which analyzed data from a series of separate confinement heterostructure quantum well Al[subx]Ga[sub1-x]As lasers of various structural design. Analysis of experimental data; Characterization of various SCH structures; Conclusion.

Investigates the optical transmission loss in dielectric waveguide bends using the finite-difference time-domain approach. Value of an absorbing boundary condition for the waveguide structure; Structures of multiple-bend waveguides; Investigation of bending loss in nonplanar laser arrays.

Provides data on strong carrier-induced antiguiding present in strained-layer indium gallium arsenide-gallium arsenide-aluminum gallium arsenide lasers. Magnitude of the carrier-induced index depression; Emission from short cavity devices; Discussion of results.

Presents a study which observed the characteristics of step-graded separate confinement quantum well lasers with direct and indirect barriers. Details on the experiment; Results of the study; Discussion of findings.

Focuses on a study which investigated the growth of gallium arsenide irradiated with ultraviolet laser light in a metalorganic chemical vapor deposition reactor. Information on laser photochemical vapor deposition; Methodology of the study; Results and discussion.

Presents information on a study which examined the switching speed of a heterostructure hot-electron diode (HHED). Illustration of an experimental current-voltage characteristic; Mechanisms underlying the switching of HHED and the effect of electron-electron interactions; Transient analysis.

Describes the surface acoustic wave (SAW) properties of aluminum gallium arsenide. Parameters used to characterize SAW properties; Measurement of the piezoelectric coupling coefficient of the substrate; Information on SAW velocities as compared to those measured on gallium arsenide.

Provides information on a study which examined the effect of the buffer-layer structures on the generation and propagation of dislocations in epitaxial layers of high composition aluminum[subx]gallium[sub1--x]arsenic through chemical vapor deposition. Experimental procedure; Results and discussion; Conclusions.

Presents a theoretical and experimental analysis of the switching mechanism in heterostructure hot-electron diodes. Prerequisite for the development of a theory for the direct current properties of hot electron diodes; Discussion of the switching mechanism in hot-electron diodes; Details of the experimental techniques used.