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BACKGROUND Patients who understand their diagnosis and treatment are more likely to be satisfied with their care and more compliant with treatment. Dermatologic surgery is a specialized field with associated jargon that many patients may not understand. OBJECTIVE The aim of the study was to assess patient understanding of dermatology medical terminology. METHODS This was a single-blinded study conducted with patients 18 years and older from an academic dermatology clinic surveying patients on 12 terms that are frequently used in dermatologic surgery. Participants rated their level of confidence in their understanding of each term using a 5-point Likert scale, followed by explaining the definition of the term. 3 blinded physicians graded each participant’s definition using a 5-point scale of accuracy of understanding, designed to mimic the Likert scale. RESULTS A total of 200 respondents completed the survey (96% response rate). The average term perceived understanding was 3.90 ±0.66, the average term accuracy was 3.26±0.93. Patients overestimated their understanding 44% of the time, and underestimated their knowledge 17% of the time. The terms with the lowest respondent confidence were the terms secondary intention, Mohs, and flaps. The terms with the lowest respondent accuracy was secondary intention, defect, and Mohs surgery. CONCLUSION There is a gap in knowledge in commonly used dermatologic surgery terms among patients. Certain demographics appear to be more at risk for not understanding medical jargon or overestimating their understanding of terms. Obtaining these patient demographics may help to identify patients needing additional education regarding dermatologic surgery. J Drugs Dermatol. 2021;20(11):1252-1254. doi:10.36849/JDD.6174.

Metastatic melanoma is a heterogeneous tumor of the skin derived from melanocytes notorious for its resistance to various forms of systemic therapy. Many different types of monotherapies and combination therapies have been developed in recent years, each with their own setbacks, and drawbacks. This review article will provide an overview of current FDA approved drug therapies for stage III and IV metastatic melanoma, key signaling pathways they target, and mechanisms of drug resistance. This paper will then look at future therapy for metastatic melanoma with a particular focus on targeted therapy on embryonic and evolutionarily conserved pathways in metastatic melanoma, including notch, wnt, hippo, hedgehog signaling, among others.

In this letter, a standard deviation based optimization technique has been applied on High Resolution X-ray Diffraction symmetric and asymmetric scan results to accurately determine the Aluminum molar fraction and lattice relaxation of Molecular Beam Epitaxy grown compositionally graded Aluminum Gallium Nitride (AlGaN)/Aluminum Nitride/Gallium Nitride (GaN) heterostructures. Mathews–Blakeslee critical thickness model has been applied in an alternative way to determine the partially relaxed AlGaN epilayer thicknesses. The coupling coefficient determination has been presented in a different perspective involving sample tilt method by offset between the asymmetric planes of GaN and AlGaN. Sample tilt is further increased to determine mosaic tilt ranging between 0.01° and 0.1°.

Metastatic melanoma is a cancer that is notoriously difficult to treat due to its ability to form resistance to various treatment regimens Cancer stem cells represent a population of tumor cells capable of self renewal and differentiation capable of maintaining the tumor and capable of resisting treatment Melanoma stem cells have also been identified with increasing amounts of information being elucidated about these cells over the past decade Therapeutic targeting of stem cells will be a key component in the fight against malignant melanoma and other cancers in the future

We report growth, by plasma-assisted molecular beam epitaxy, of thin Al0.2Ga0.8N/GaN and In0.17Al0.83N/GaN heterostructures on Si(111) substrate with three different buffer thickness (600, 400, and 200 nm). Successful growth by critical optimization of growth conditions was followed by comparative characterization of these heterostructures by use of high resolution x-ray diffraction (HRXRD), including reciprocal space mapping (RSM), room-temperature photoluminescence (RT-PL), and high resolution transmission electron microscopy (HRTEM). The effect of different buffer thickness on the threading dislocation (TD) density of a thin 1.5 nm Al0.2Ga0.8N/In0.17Al0.83N–1.25 nm GaN–1.5 nm Al0.2Ga0.8N/In0.17Al0.83N heterostructure, was also studied. Analysis revealed increasing tensile strain with decreasing buffer thickness for AlGaN-based samples; this was confirmed by the red-shift of the GaN RT-PL peak. Reduced strain in lattice-matched InAlN-based samples resulted in a blue-shift of the GaN RT-PL peak; this was indicative of better crystallographic quality than for the AlGaN/GaN samples, which was proved by XRD-FWHM and RSM results. A substantial reduction of TD density from approximately 1010 to 108 cm−2 with increasing buffer thickness resulted in a smooth thin active region for both thick buffer structures whereas the lattice-matched InAlN/GaN-based thick buffer resulted in less effect on TD and a smooth and prominent thin active region.

In this paper, we detailed a novel 3D detection method for geometric features in CAD models used in CAD-to-CAE model simplification process. Model preparation is now the most time consuming part in the computer-aided engineering process chain, it is commonly labor intensive. Therefore, the overall objectives are: 1) introduce automation to speed-up the model preparation process; 2) remove redundant features to reduce model mesh size for fast mesh generation and analysis without compromising on solution accuracy. Automatic feature detection that is generic and easily extendable is a key element needed to achieve these objectives. Inside the article, we proposed detection by characteristics to complement existing geometric modeling kernels for CAD systems with defeaturing functions to detect features previously not detectable.

This paper presents an approach of compositional grading of the barrier in AlGaN/GaN quantum well heterostructure to achieve high two dimensional electron gas (2DEG) carrier concentration and mobility for RF power amplifier applications. Plasma assisted Molecular Beam Epitaxy (PAMBE) has been used to grow compositionally graded AlGaN/GaN and AlGaN/AlN/GaN heterostructures. In-situ cathodoluminescence (CL) and ex-situ high resolution x-ray diffraction (HRXRD) along with high resolution transmission electron microscopy (HRTEM) techniques were used to study the compositions and thicknesses of grown heterostructures. Ohmic contact formation for all the samples were found to be challenging due to unusual surface behavior and thus addressed with three different metallization schemes. The graded AlGaN/GaN and AlGaN/AlN/GaN heterostructures show 2DEG carrier concentrations of 2.0 × 1013 cm−2 and 2.3 × 1013 cm−2 with carrier mobility of 764 cm2v−1s−1 and 960 cm2v−1s−1, respectively at room temperature. A performance index has been proposed to correlate the obtained results with its suitability for particular RF applications.

A comparative assessment of AlGaN/GaN high-electron-mobility transistors (HEMTs) grown by molecular beam epitaxy on silicon and sapphire substrates has been carried out. Large-area power GaN HEMTs with identical device dimensions were fabricated on both substrates. A thicker AlN buffer layer was used for the GaN HEMT on silicon to achieve similar quality and uniformity of GaN epitaxy for rational comparison with that grown on sapphire. Direct-current analysis and physical characterization were carried out to understand the performance of the devices. Mathematical measurement of the instability of the current–voltage (I–V) characteristic at high applied drain bias was carried out to evaluate the performance of both devices. An improved two-dimensional (2D) analysis of the I–V characteristic was performed from a thermal perspective including appropriate scattering effects on the 2D electron gas mobility. The experimental and analytical studies were correlated to reveal the effects of temperature-sensitive scattering phenomena on the mobility as well as on the I–V characteristic at high drain bias in terms of lattice thermal heating. It is observed that the HEMT on Si has improved stability compared with sapphire due to its weaker scattering phenomena at high drain bias, associated with its thermal conductivity. Simulation of 2D thermal mapping was also carried out to distinguish the hot-spot regions of the devices. The comparable electrical performance of these devices illustrates the viability of AlGaN/GaN HEMTs on Si(111) to achieve low-cost stable devices with better thermal power handling for high-voltage applications.

The performance of InAlAs/InGaAs quantum well field effect transistors are subject to high impact ionization and band-to-band tunneling (BTBT) due to its narrow bandgap feature. In this work, the energy gap is engineered using strain and quantization techniques to increase the effective energy gap leading to low impact ionization and BTBT leakage current. It is shown that the impact ionization is reduced in 5 nm channel device as compared to 13 nm device with onset at approximately Egeff/q. Also the band-to-band-tunneling current is reduced due to the increase in effective energy gap. We have also investigated the effects of quantum well engineering on the dc performance of InGaAs HEMTs.

Graphic Processing Units (GPUs) have greatly exceeded their initial role of graphics accelerators and have taken a new role of co-processors for computation—heavy tasks. Both hardware and software ecosystems have now matured, with fully IEEE compliant double precision and memory correction being supported and a rich set of software tools and libraries being available. This in turn has lead to their increased adoption in a growing number of fields, both in academia and, more recently, in industry. In this review we investigate the adoption of GPUs as accelerators in the field of Finite Element Structural Analysis, a design tool that is now essential in many branches of engineering. We survey the work that has been done in accelerating the most time consuming steps of the analysis, indicate the speedup that has been achieved and, where available, highlight software libraries and packages that will enable the reader to take advantage of such acceleration. Overall, we try to draw a high level picture of where the state of the art is currently at.

AlGaN/GaN high electron mobility transistors (HEMTs) functionalized with ZnO nanorods were used for sensing CO in the concentration range of 50–500 ppm balanced with air at ambient and temperatures from 25 to 250 °C. An increase of the HEMT drain current was observed for exposure to the CO-containing ambient. The sensing limitation was improved from 100 ppm to 50 ppm by increasing the sensor temperature from room temperature to 250 °C. The sensing response was also enhanced from 0.09% to 0.34% by increasing the sensor temperature. Reliable and repeatable current changes with the introduction of a low CO concentration of 50 ppm and also rapid response times of ∼40 s and recovery times ∼15 s were demonstrated.

In this study, we report on a demonstration of hydrogen sensing at low temperature using SnO2 functionalized AlGaN/GaN high electron mobility transistors (HEMT). The SnO2 dispersion was synthesized via a hydrothermal method and selectively deposited on the gate region of a HEMT device through a photolithography process. The high electron sheet carrier concentration of nitride HEMTs provides an increased sensitivity relative to simple Schottky diodes fabricated on GaN layers. The morphology and crystalline properties of the SnO2-gate, together with the texture of the multilayer films on the device were investigated by SEM, HRTEM, EDS and XRD. The effects of annealing treatment on the crystalline properties of the SnO2-gate, and gas sensing properties of SnO2-gated HEMT sensors were studied. The SnO2-gated HEMT sensor showed fast and reversible hydrogen gas sensing response at low temperature.

This paper presents high performance device results using an ultra-thin AlN / GaN structure on sapphire substrate with a 100-nm T -gate. Excellent dc and RF characteristics are reported, including an extrinsic transconductance of 500 mS/mm and an extrinsic f t / f max ( U ) ratio of 78/111-GHz which is among the highest reported for AlN / GaN HFETs. Low gate leakage results are also presented despite the small barrier thickness and absence of a gate dielectric. Modeling of the small signal parameters is also discussed to gain an understanding of the limiting and contributing performance factors.

AlN/GaN high electron mobility transistors (HEMTs) were irradiated with 5 MeV protons at fluences from 2×1011 to 2×1015 protons/cm2. Changes from 10% to 35% of the saturation drain current and the source-drain resistances were observed for the HEMTs exposed to the proton irradiations due to radiation-induced carrier scattering and carrier removal. Both forward and reverse bias gate currents were increased after proton irradiation and affected the drain current modulation in the positive gate bias voltage range. There was almost no gate-lag observed for the HEMT exposed to 2×1011 protons/cm2 irradiation and minimal changes for the higher doses, which implied that few surface traps were created by the high energy proton irradiation.

We report on the novel normally-on/off AlN/GaN high electron mobility transistors (HEMTs) grown by plasma-assisted molecular beam epitaxy. With simple oxygen exposure, the threshold voltage can be tuned from -2.76 V to +1.13 V depending on the treatment time. The gate current was reduced and current-voltage curves show metal-oxide semiconductor diode-like characteristics after oxygen plasma exposure. The extrinsic transconductance of HEMTs decrease with increasing oxygen plasma exposure time due to the thicker Al oxide formed on the gate area. The unity current gain cut-off frequency, fT, and maximum frequency of oscillation, fmax, were 20.4 GHz and 36.5 GHz, respectively for an enhancement-mode HEMT with the gate dimension of 0.4 × 100 μm2. (© 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

The long-term stability of antibody-functionalized, Au-gated AlGaN/GaN high electron mobility transistors for detecting botulinum toxin is reported in this study. The botulinum toxin sensor, which initially showed good data reproducibility and recyclability, was repeatedly tested over a 9-month period. The botulinum sensor was packaged and stored in phosphate buffered saline (PBS) at 4 °C in a refrigerator for long-term storage. The sensor was tested over time at room temperature and we found sensitivity losses of 2%, 12% and 28% after 3, 6 and 9 months, respectively. These results clearly demonstrate a significant step towards the realization of electronic detection of biomolecules by field-deployed sensor chips based on AlGaN/GaN HEMTs.

Ozone treatment of AlN on AlN∕GaN heterostructures produces effective surface passivation and chemical resistance to the AZ positive photoresist developer used for subsequent device fabrication. The ozone-passivated AlN∕GaN high electron mobility transistors (HEMTs) exhibited low gate leakage currents, high gate modulation voltage, and minimal drain current degradation during gate pulse measurements. With an additional oxygen plasma treatment on the gate area prior to the gate metal deposition, enhancement-mode AlN∕GaN high electron mobility transistors were realized. The gate characteristics of the HEMTs treated with the ozone and oxygen plasma behaved in a manner similar to a metal oxide semiconductor diodelike gate current-voltage characteristic instead of a Schottky diode. Drain breakdown voltages of 23 and 43V for d- and e-mode HEMTs were obtained, respectively. For d-mode HEMTs, there was no reduction in the drain current during the gate pulse measurements at frequencies of 1, 10, and 100kHz. For th...

AlGaN/GaN high electron mobility transistors (HEMTs) were used to detect botulinum toxin. The gate area was deposited with Au and thioglycolic acid. The antibody was anchored on the gate area. The AlGaN/GaN HEMT drain-source current showed a rapid response of less than 5 seconds when the target toxin in a buffer was added to the antibody-immobilized surface. Different concentrations (from 0.1 ng/ml to 100 ng/ml) of the exposed target botulinum toxin in a buffer solution were detected. The sensor showed low detection limit of less than 1ng/ml and saturates above 10ng/ml of the toxin. The sensor was recycled with the phosphate buffered saline (PBS) after the toxin detection and still showed the same sensitivity.

We have demonstrated a wireless hydrogen sensing system using commercially available wireless components and AlGaN/GaN high electron mobility transistor (HEMTs) differential sensing diodes as the sensing devices. The active device in the differential pair is coated with 10 nm of Pt to enhance catalytic dissociation of molecular hydrogen, while the reference diode is coated with Ti/Au. Our sensors have a wide range of detection from ppm levels to ∼30%, with the added advantages of a very rapid response time within a couple of seconds, and rapid recovery. The sensors have shown good stability for more than 18 months in an outdoor field test. Currently, the wireless sensing system consists of six wireless sensor nodes and a base station. The wireless sensor node consists of a sensor, a power management system with back-up batteries in case of power outages and a wireless transceiver. The base station consists of a high sensitivity receiver and an in-house developed intelligent monitoring software that does basic data logging and tracking of each individual sensor. The software defines and implements the monitoring states, transitions, and actions of the hydrogen sensor network. Also, the software is able to warn the user of potential sensor failure, power outages and network failures through cell phone network and Internet. Real-time responses of the sensors are displayed through a web site on the Internet. ( http://ren.che.ufl.edu/app/default.aspx ).

We have demonstrated a wireless hydrogen sensing system using commercially available wireless components and AlGaN/GaN High Electron Mobility Transistor (HEMTs) differential sensing diodes as the sensing devices. The active device in the differential pair is coated with 10 nm of Pt to enhance catalytic dissociation of molecular hydrogen, while the reference diode is coated with Ti/Au. Our sensors have a wide range of detection from ppm levels to ~30%, with the added advantages of a very rapid response time within a couple of seconds, and rapid recovery. The sensors have shown good stability for more than 18 months in an outdoor field test.

AlGaN/ GaN High Electron Mobility Transistors (HEMTS) were used to detect pH value and glucose concentration in the exhaled breath condensate (EBC). A Peltier element mounted on the backside of the AlGaN/GaN HEMT was used to lower the temperature of the sensor in order to condense the exhaled breath. The measured current change of the HEMT shows that the pH of the condensate from the exhaled breath is within the range of 7- 8, corresponding to the range of interest for human blood. The sensor exhibited a repeatable change of 1.24 mA/mm of the drain current at a drain bias of 0.25V, when the surface was exposed to repeated exhalations. ZnO nanorod-gated AlGaN/GaN HEMTs were used to detect glucose in EBC. A ZnO nanorod array was selectively grown on the gate area using low temperature hydrothermal decomposition to immobilize glucose oxidase (GOx).

Wurtzite CdxZn1−xO epilayers with cadmium concentrations ranging from x = 0.02 to 0.30 were investigated using photoluminescence, transmission/reflection spectroscopy, and atomic force microscopy. The CdxZn1−xO photoluminescence peak was found to shift through the visible region from 421 (2.95 eV) to 619 nm (2.0 eV) as the cadmium concentration was increased from 2% to 30%. An additional broad photoluminescence peak was observed and is attributed to deep levels – the center of the broad peak was found to shift from 675 to 750 nm as the cadmium concentration was increased. RMS roughness of the epilayers increased from 1.5 nm (x = 0.02) to 9.2 nm (x = 0.30), as determined from atomic force microscopy. The demonstrated visible wavelength tunability throughout the visible range verifies the viability of using wurtzite CdxZn1−xO compounds for visible light emission in future optoelectronic devices.

In the paper we present band-gap alignment diagrams for type-II/type-I heterostructures incorporating the strong piezoelectric and spontaneous polarization fields in ZnCdMgO and AlGaN-based materials and interfaces. The paper describes some of the recent progress made in the development of high quality ZnCdO layers and CdZnO/ZnO heterostructures grown epitaxially by RF-plasma molecular beam epitaxy (MBE). We summarize optical and electrical properties of high quality CdxZn1-xO alloys with Cd mole fraction from 0.02 to 0.78 and discuss phase separation phenomenon, which may be present in ternary alloys. A single-crystal wurtzite structure of CdZnO alloys has been confirmed. We achieved a strong optical emission at RT in the 380 nm to 574 nm spectral range from CdxZn1-xO with various compositions. Dependence of the fundamental optical band gap on the composition of CdxZn1- xO alloys, band gap bowing, and the possible effect of composition micro-fluctuations in ternary CdxZn1-xO alloys on the optical bandgap is also discussed. Time resolved photoluminescence shows multi-exponential decay with 21 psec. and 49{plus minus}3 psec. lifetimes, suggesting that composition micro- fluctuations may be present in Cd0.16Zn0.84O film. We also report on crystallographic and optical properties of CdZnO/ZnO multiple quantum wells.

We report on the fabrication and characterization of an ultraviolet (UV) light-emitting diode (LED) based on a p-n junction MgZnO/ZnO/AlGaN/GaN semiconductor triple-heterostructure (THS). Radio-frequency (RF) plasma-assisted molecular-beam epitaxy (MBE) has been employed to grow individual epitaxial layers of ZnO, MgxZn1−xO, and the complete heterostructure on c-plane GaN/sapphire templates. Various growth strategies have been used to optimize the quality of the ZnO layers as well as to precisely control the composition of the MgxZn1−xO compound. Cross-sectional transmission electron microscopy (TEM) study shows the excellent crystalline quality of the pseudomorphically grown ZnO active region of the device. A strong electroluminescence (EL) emission associated with ZnO excitonic transition was observed up to 650 K. The results shown in this paper strongly suggest the viability of RF plasma-assisted MBE in the development of next-generation UV emitters using ZnO-based materials.

We investigated different Er3+ defect sites found in Er-doped GaN layers by site-selective combined excitation-emission spectroscopy and studied the role of these sites in different direct and multistep excitation schemes. The layers were grown by molecular beam epitaxy and were 200 nm thick. Two majority sites were found along with several minority sites. The sites strongly differ in excitation and energy transfer efficiencies as well as branching ratios during relaxation. For this reason, relative emission intensities from these sites depend strongly on emission and excitation. The sites were identified for several transitions and a comprehensive list of energy levels has been compiled. One of the minority sites appears strongly under ultraviolet excitation above the GaN band gap suggesting that this site is an excellent trap for excitation energy of electron-hole pairs.