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Gallium nitride (GaN) high electron-mobility transistors (HEMTs) offer considerable high-power operation but suffer in reliability due to potentially damaging self-heating. In this study, self-heating in AlGaN/GaN HEMTs on high conductivity substrates is assessed using a high-resolution thermoreflectance (TR) imaging technique, to compare the thermal response between GaN-on-Si, GaN-on-Diamond, and GaN-on-4H-SiC. The TR method accuracy at high-power density is verified using a nonlinear coefficient of TR (CTR) as a function of temperature. The acquired steady-state thermal maps give a thermal resistance of 11.5~mm ⋅ K/W for GaN-on-Si (based on peak channel temperature), compared to 2.7 and 3.3~mm ⋅ K/W for GaN-on-SiC and GaN-on-diamond substrates, respectively. The tested GaN-on-diamond HEMT exhibits similar heating rates to those seen on a SiC substrate, with a slightly higher peak temperature, which indicates a higher thermal boundary resistance that could offset the benefits of using a higher conductivity substrate and lead to faster thermally enhanced degradation. The analysis reveals the importance using high-resolution imaging to detect hotspots and areas of peak temperature that largely affect failure initiation and device reliability and which may not be otherwise observable. [ABSTRACT FROM AUTHOR]

GaN is a favorable martial for future efficient high voltage power switches. GaN has not dominated the power electronics market due to immature substrate, homoepitaxial growth, and immature processing technology. Understanding the impact of the substrate and homoepitaxial growth on the device performance is crucial for boosting the performance of GaN. In this work, we studied vertical GaN PiN diodes that were fabricated on non-homogenous Hydride Vapor Phase Epitaxy (HVPE) substrates from two different vendors. We show that defects which stemmed from growth techniques manifest themselves as leakage hubs. Different non-homogenous substrates showed different distribution of those defects spatially with the lesser quality substrates clustering those defects in clusters that causes pre-mature breakdown. Energetically these defects are mostly mid-gap around 1.8Ev with light emission spans from 450nm to 700nm. Photon emission spectrometry and hyperspectral electroluminescence were used to locate these defects spatially and energetically. [ABSTRACT FROM AUTHOR]

Plasma etching of p-type GaN creates n-type nitrogen vacancy (VN) defects at the etched surface, which can be detrimental to device performance. In mesa isolated diodes, etch damage on the sidewalls degrades the ideality factor and leakage current. A treatment was developed to recover both the ideality factor and leakage current, which uses UV/O3 treatment to oxidize the damaged layers followed by HF etching to remove them. The temperature dependent I–V measurement shows that the reverse leakage transport mechanism is dominated by Poole–Frenkel emission at room temperature through the etch-induced VN defect. Depth resolved cathodoluminescence confirms that the damage is limited to first several nanometers and is consistent with the VN defect. [ABSTRACT FROM AUTHOR]

About 2 MeV proton numerical calculation damage indicates that a quasiflat profile is introduced into the GaN buffer layer of high‐electron‐mobility transistor (HEMT) templates. A previous transport study of such HEMT structures showed increased breakdown voltage and reduced GaN buffer layer leakage after proton irradiation. Hyperspectral electroluminescence measurements detected the emission band in the spectral region between 700 and 800 nm. This emission is assumed to be associated with the generation of trap levels responsible for the device failure. To obtain insights into the nature of radiation‐generated traps, detailed low‐temperature photoluminescence (PL) and cathodoluminescence (CL) experiments are conducted in a set of virgin and proton‐irradiated device structure templates. Both the PL and CL spectra show large intensity variations of all emission bands, in the spectral range between 330 and 890 nm, with increasing proton dosage. This is consistent with the introduction of compensating and/or nonradiative recombination centers in the GaN buffer layer. Luminescence measurements carried out under various excitation conditions show different recombination rates for emission bands observed near 420 and 550 nm, indicating different free carrier capture rates. Spectral analysis suggests that these two emission bands have different dependences on proton irradiation dosage, consistent with different chemical natures. [ABSTRACT FROM AUTHOR]

Ion implantation of magnesium for p‐type GaN presents many opportunities; however, activation has proven difficult due to the decomposition of GaN at relevant annealing temperatures. Herein, testing the efficacy of multiple in situ and ex situ caps based on aluminum nitride and silicon nitride for GaN protection during annealing is presented. Photoluminescence shows better activation for in situ metal organic chemical vapor deposition (MOCVD)‐grown aluminum nitride caps compared with ex situ sputtered aluminum nitride and the best performance by ex situ plasma‐enhanced chemical vapor deposition (PECVD) silicon nitride. Furthermore, only samples annealed at the highest temperatures tested show preferential growth of UV luminescence to yellow‐green luminescence reinforcing the need for better capping solutions and higher temperature annealing. [ABSTRACT FROM AUTHOR]

Negatively substituted trimethylenecyclopropane dianions, a subclass of hexasubstituted [3]radialenes, are candidates for use as active species in redox flow batteries (RFBs) due to their stability in water, reversible electrochemistry, and tailorable synthesis. Hexacyano[3]radialene disodium is investigated as a pH 7 aqueous organic catholyte. The dianion and radical anion are stable in air and aqueous solutions at neutral pH. Systematic introduction of asymmetry via step-wise synthesis leads to enhanced solubility and higher capacity retention during galvanostatic cycling. An aqueous flow cell comprising a diester-tetracyano[3]radialene catholyte, sulfonated-methyl viologen as the anolyte, and a cation exchange membrane provides an operating Vcell = 0.9 V, 99.609% coulombic efficiency, and minimum capacity fade over 50 cycles. [ABSTRACT FROM AUTHOR]

We report selective area n-type doping using ion implantation of Si into semi-insulating, C-doped GaN samples activated using both conventional rapid thermal annealing (RTA) and 30 atm N2 overpressure annealing. Implanted regions were tested for Si activation using Circular Transmission Line Measurements (CTLM), while linear and circular photoconductive switches (PCSS) in the unimplanted regions were used as a test vehicle to separate implanted Si dopant activation from leakage paths generated by N vacancy formation due to damage and decomposition during annealing. We observed that at an optimal temperature around 1060 °C, a low contact resistivity of $1\times 10^{-6}\,\,\Omega $ -cm2 was obtained while preserving the breakdown of the unimplanted regions. [ABSTRACT FROM AUTHOR]

The [Na.sup.+] and [[Cu[(en).sub.2][([H.sub.2]O).sub.2]].sup.2+] (en = ethylenediamine) salt of a pseudosandwich-type heteropolyniobate is formed upon prolonged heating of Cu[)N[O.sub.3]).sub.2] and hydrated [Na.sub.14][[(SiOH).sub.2][Si.sub.2][Nb.sub.16][O.sub.54]] in a mixed water-en solution. The studies have shown that unlike tungsten-based sandwich-type complexes, the [[Na[(SiOH).sub.2][Si.sub.2][Nb.sub.16][O.sub.54]].sup.13-] units are linked exclusively by [Na.sup.+] instead of one or more d-electron metals.

Oxygen-isotope-exchange rates were measured on the Ta(V) Lindquist ions as a function of the pH and temperature. Result shows tantalizing differences in reactivities.

To study the demetalation process observed upon reduction of Fe(III) centers in a large family of multi-iron Wells-Dawson polyoxometalates, the cyclic voltammetry and controlled potential coulometry is used. A report showing a series of multi-iron sandwich-type complexes that are effective catalysts is presented.

The decomposition of A-type sandwich polyoxometalate complexes is investigated. A crystallographic study is done, which shows the formation of a new type of polyanion.

A-type sandwich polyoxometalate,(YOH2)3(CO3)(A-alpha-PW9O34)(super 11-) is discussed. Ions.(super 31) P and (super 13)C, NMR studies confirm that this complex is significantly more stable than the analogous A-type sandwich polyoxometalates containing divalent metals.

Research has been conducted on coordination network polymer which involves redox-active polyanion. The authors describe the characterization of this polymer via the use X-ray crystallography.

Research describes the synthesis and characterization of multi-iron sandwich-type polyoxometalates. Data indicate that the compound mediates electrocatalytic reduction of dioxygen and hydrogen peroxide.

Here, we demonstrate the effects of surface functionalization on a tunable series of nano-sized electron shuttles, toward improving their function in nonaqueous energy storage. The synthesis of a series of polyoxovanadium clusters featuring bridging ether functional groups is reported, revealing the influence of bridging "R" group identity on electrochemical stability in solution. Furthermore, the presence of bridging ether moeities yields enhanced solubility in acetonitrile (up to 1.2 M), highlighting synthetic strategies for the development of organofunctionalized polyoxometalate-derived charge carriers for nonaqueous, electrochemical energy storage. [ABSTRACT FROM AUTHOR]

The performances of five commercial anion exchange membranes are compared in aqueous soluble organic redox flow batteries (RFBs) containing the TEMPO and methyl viologen (MV) redox pair. Capacities between RFBs with different membranes are found to vary by >50% of theoretical after 100 cycles. This capacity loss is attributed to crossover of TEMPO and MV across the membrane and is dominated by either diffusion, migration, or electroosmotic drag, depending on the membrane. Counterintuitively, the worst performing membranes display the lowest diffusion coefficients for TEMPO and MV, instead seeing high crossover fluxes due to electroosmotic drag. This trend is rationalized in terms of the ion exchange capacity and water content of these membranes. Decreasing these values in an effort to minimize diffusion of the redox-active species while the RFB rests can inadvertently exacerbate conditions for electroosmotic drag when theRFBoperates. Using fundamental membrane properties, it is demonstrated that the relative magnitude of crossover and capacity loss during RFB operation may be understood. [ABSTRACT FROM AUTHOR]

Context: Although fatigue has been implicated in anterior cruciate ligament (ACL) injury, few researchers have examined the timing of injury across a competitive sport season or within a competitive session to gain insight into the potential effects of fatigue on the incidence of ACL injury. Objective: To identify the time segments across a competitive season or within an individual competition associated with the greatest ACL injury incidence. Design: Descriptive epidemiology study. Methods: Data from the National Collegiate Athletic Association Injury Surveillance Program for 2004-2005 through 2015-2016 for basketball, lacrosse, and soccer were analyzed. Incidence rate ratios (IRRs) compared ACL injury rates by sport, sex, season segment, and competition period. Poisson regression was used to examine the associations between each of these categories and the incidence of ACL injury as well as interaction effects. Results: During the early regular season, the incidence rate was elevated relative to the preseason (IRR = 1.86; 95% confidence interval [CI] = 1.27, 2.74), middle regular season (IRR = 1.48; 95% CI = 1.01, 2.15), late regular season (IRR = 1.56; 95% CI=1.08, 2.27), and postseason (IRR=2.20; 95% CI = 1.06, 4.56). A sport-by-season interaction indicated this effect was largely attributable to a higher incidence in the early season among lacrosse athletes. An interaction between season segment and competition period (P = .02) revealed a greater injury incidence before halftime in the early regular season (IRR = 0.38, 95% CI = 0.19, 0.76), but a greater incidence after halftime in the late regular season (IRR = 2.40, 95% CI = 1.15, 5.02). Fewer noncontact injuries occurred in soccer than in basketball or lacrosse. Conclusions: The ACL injury incidence was higher in the early part of the regular season, particularly among lacrosse athletes. Although the injury incidences before and after halftime were similar, further analyses of player time and time of injury within each half are necessary. Coaches and practitioners should be cognizant of the elevated injury incidence during the early season among lacrosse athletes. Future authors should consider more specific analyses to further elucidate the potential role of fatigue development in exacerbating the incidence of ACL injury in collegiate athletes both within games and across the season. [ABSTRACT FROM AUTHOR]

Record DC power has been demonstrated in AlGaN/GaN high electron mobility transistors fabricated using a substrate replacement process in which a thick diamond substrate is grown by chemical vapor deposition following removal of the original Si substrate. Crucial to the process is a ~30 nm thick SiN interlayer that has been optimized for thermal resistance. The reductions obtained in self-heating have been quantified by transient thermoreflectance imaging and interpreted using 3D numerical simulation. With a DC power dissipation level of 56 W/mm, the measured average and maximum temperatures in the gate-drain access region were 176 °C and 205 °C, respectively. [ABSTRACT FROM AUTHOR]

Evidence suggests menstrual cycle variation in the hormone relaxin may have an impact on ligament integrity and may be associated with risk of anterior cruciate ligament injury in physically active women. However, studies to date have only detected relaxin in a small number of participants, possibly due to inter-individual variability, frequency of sample collection, or analytical techniques. Therefore, the purpose of this study was to analyze serial serum samples in moderately active, eumenorrheic women to identify the proportion of women with detectable relaxin concentrations. Secondary analyses were conducted on two independent data sets. Data Set I (DSI; N = 66) participants provided samples for 6 days of menses and 8–10 days of the luteal phase. Data Set II (DSII; N = 15) participants provided samples every 2–3 days for a full menstrual cycle. Samples were analyzed via a relaxin-2 specific ELISA assay. Limit of detection (LOD) was calculated from the empirical assay data. LOD was calculated as 3.57 pg·ml−1. Relaxin concentrations exceeded the LOD in 90.91% (DSI) and 93.33% (DSII) of participants on at least 1 day of sampling. Actual peak values ranged from 0.0 pg·ml−1 to 118.0 pg·ml−1. Relaxin was detectable in a higher proportion of young women representing a broad range of physical activity levels when sampled more frequently. Future studies investigating relaxin should consider sampling on more than 1 day to accurately capture values among normal menstruating women. [ABSTRACT FROM AUTHOR]

Threading and basal dislocations were observed and their Burgers vectors ( b → ) were analyzed in 20 µm thick halide vapor phase homoepitaxially grown beta-gallium oxide (β−Ga2O3) films using 15 keV monochromatic synchrotron X-ray topography with symmetric reflection (004) and two asymmetric reflections (205) and (115) in back-reflection and grazing incidence angle geometries, respectively. In a 1 × 1.5 cm2 sample, threading screw dislocations with b → = 001 were observed with a density of 30 cm−2, whereas a single threading edge dislocation with b → = 100 was observed. Basal dislocations with b → = 1 2 112 were observed with a density of ∼20 cm−2, and a single basal dislocation with b → = 010 was observed. Rocking curve mapping of the three reflections was also performed on the entire sample with the same setup and a high resolution x-ray camera to obtain the full width at half maximum (FWHM), strain, and curvature maps in two almost orthogonal directions. The epilayer demonstrated excellent crystalline quality with a median FWHM of 8.2 arc sec in the (004) reflection and a very low median strain of ∼|8 × 10−5| obtained from both sample directions. The median radius of curvature was ∼−100 m along the [100] direction and ∼280 m along the [010] sample axis, indicating very low lattice plane curvature that enables high manufacturability and reliability of devices. [ABSTRACT FROM AUTHOR]

Semi-insulating halide vapor phase epitaxial β-Ga2O3 films without intentional dopants introduced during growth are demonstrated. The sheet resistance measured in the 340–480 K range yielded 268–134 kΩ/◻ and an activation energy of 0.81 eV. Room temperature capacitance-voltage measurements at 1 MHz showed evidence of an ultra-low free carrier concentration n-type film with a free carrier concentration near flatband (VFB ∼ 4.4 V) estimated to be <1014 cm−3, resulting in a high breakdown voltage of 2380 V (3.18 MV/cm) measured on a lateral diode without field termination. Secondary ion mass spectroscopy did not reveal Fe compensating species; however, an average Si concentration of about 5 × 1015 cm−3 and an N concentration of about 2 × 1017 cm−3 were detected, suggesting that N acceptors compensated Si donors to result in a nearly intrinsic β-Ga2O3 film. Photoionization spectroscopy suggested the presence of a deep acceptor-like level located at Ec −0.23 eV. [ABSTRACT FROM AUTHOR]

A new type of synthesis resulting in a new type of sandwich polyoxmetalates is synthesized and characterized. This new synthesis replaces the old Wells-Dawson-derived sandwich type polyoxometalates.

Background: Thinning of the posterior cingulate cortex (PCC) is implicated in Alzheimer's disease (AD). Though some evidence suggests ApolipoproteinE (APOE) ε4 carriers (ε4+) have thinner PCCs than non‐carriers (ε4‐), the evidence is conflicting and lacks association with learning outcomes relevant to AD. Method: A subset from an ongoing clinical trial (NIH/NIA: R01AG058919) was used for analyses and included 26 ε4+ (73% female, Agemean=55.81±5.53) and 42 ε4‐ (88% female, Agemean= 57.54±5.10), who were all cognitively normal, sedentary, and had a family history of AD. Genetic sampling was completed via passive drool. Structural MRI was completed to assess PCC cortical thickness, and the Rey Auditory Verbal Learning Task (AVLT) was used to assess learning. Brain segmentation was completed with Freesurfer's automated pipeline, and left and right PCC cortical thickness was extracted for analysis. A learning over trials (LOT) composite score from the AVLT was calculated to represent learning. An analysis of covariance was completed to assess the effect of carrier status on left/right PCC thickness, controlling for age and sex. Linear regressions were completed to assess main effects and interaction of carrier status and left/right PCC thickness in predicting LOT when controlling for age and sex. Result: ε4+ had less cortical thickness in the left PCC (F(1,64)=5.07, p=.03), but not the right PCC (p=.33), relative to ε4‐. Carrier status predicted LOT (Left: F(1,62)=10.37, p<.01; Right: F(1,62)=10.66, p<.01), however this was superseded by significant interactions between carrier status and PCC thickness predicting LOT (Left: F(1,62)=10.72, p<.01; Right: F(1, 62)=11.10, p<.01), with post‐hoc analyses demonstrating PCC thickness predicts LOT for ε4+ (Left:β=‐21.07, p=.04; Right:β=‐24.33, p<.01), but not ε4‐ (p's>.09). Conclusion: In cognitively normal sedentary adults with a family history of AD, carrying the APOE ε4 allele was associated with a thinner left PCC. Further, thinner bilateral PCCs in ε4+ were associated with greater learning during the AVLT task. This suggests that ε4+ may have compensatory neural pathways to account for losses in the PCC, which temporarily bolster learning to delay the onset of AD. However, additional research is needed to continue understanding the neural mechanisms affected by carrying the APOE ε4 allele. [ABSTRACT FROM AUTHOR]

Background: The Apolipoprotein E (APOE) ε4 allele has been identified as a critical genetic risk factor for developing Alzheimer's disease. Heart rate variability (HRV) metrics are non‐invasive indicators of autonomic nervous system function associated with cognitive performance in patients with dementia and mild cognitive impairment. Some evidence suggests reduced HRV complexity in elderly adults carrying the ε4 allele beyond the effects of aging. However, no study has evaluated whether cognitively normal middle‐aged adults differ in their HRV based on their APOE carrier status. Method: The present cross‐sectional analysis was based on the larger Physical Activity and Alzheimer's Disease 2 clinical trial (NIH: R01AG058919). Eighty‐six cognitively normal middle‐aged adults (sex: 85.9% female; age: 57.5±5.9 years; height: 166.5±8.8 cm; mass: 78.3±18.8 kg) had height, mass, and resting blood pressure assessed and completed a series of surveys. Participants provided a saliva sample via passive drool to determine APOE ε4 carrier status and also completed a 5‐minute seated electrocardiogram assessment. R‐waves were identified, and the RR interval time series were filtered prior to HRV analysis. HRV metrics of the standard deviation of the normal‐to‐normal interval, root mean square of successive differences, high and low‐frequency power, and sample entropy were calculated. Differences in HRV metrics between ε4 carriers (n = 32) and non‐carriers (n = 54) were tested via general linear models. Differences were also tested after controlling for sex, age, education, ethnicity, body mass index, moderate to vigorous physical activity, and mean arterial pressure. Result: No differences in any HRV metric were observed between APOE ε4 carriers and non‐carriers (all p's > 0.05), including after controlling for all and sets of covariates. Conclusion: The absence of significant associations between carrier status and HRV in cognitively normal adults suggests that HRV is not predictive of Alzheimer's disease risk in the same manner as genetic factors. Rather, HRV may be concurrently altered with cognitive decline and thus serve as a non‐invasive biomarker that could be monitored to indicate when more intensive cognitive testing is required. Future research should test the similarity in HRV and cognition trajectories in APOE ε4 carriers and non‐carriers. [ABSTRACT FROM AUTHOR]

The electrical quality of HfO2 dielectrics grown by thermal atomic layer deposition at 175 °C on n-type (201) β-Ga2O3 has been studied through capacitance- and current-voltage measurements on metal-oxide-semiconductor capacitors. These capacitors exhibited excellent electrical characteristics, including dual-sweep capacitance-voltage curves with low hysteresis and stretch-out and a frequency-stable dielectric constant of k ~14 when measured between 10 kHz and 1MHz. The C-V curves exhibited a uniform and repeatable +1.05V shift relative to the ideal case when swept from 3.5 to ~5V, yielding positively measured flatband (+2.15 V) and threshold (+1.05 V) voltages that may be useful for normally off n-channel Ga2O3 devices. Using the Terman method, an average interface trap density of 1.3 x 1011 cm-2eV-1 was obtained between 0.2 and 0.6 eV below the conduction band edge. The forward bias current-voltage characteristic was successfully fitted to the Fowler-Nordheim tunneling model at a field strength of 5MV/cm, allowing an extraction of a 1.3 eV conduction band offset between HfO2 and Ga2O3, which matches the value previously determined from x-ray photoelectron spectroscopy. However, a temperature dependence in the leakage current was observed. These results suggest that HfO2 is an appealing dielectric for Ga2O3 device applications. [ABSTRACT FROM AUTHOR]

Terminal oxo complexes of the late-transition-metal elements are proposed as possible intermediates for oxidations catalyzed by these elements and in technologies where these elements encounter O2 or other oxidants. A unique Pd-oxo compound, K10Na3[Pd(super IV)O(OH)WO(OH2)-(PW9O34)2 is prepared and fully characterized.

The preparation and characterization of a new type of material comprised of anionic metal oxygen clusters (polyoxometalates or POMs) that are electrostatically bound to cationic silica nanoparticles is reported. The binding of a new sandwich-type POM (super 4) of formula, [((Fe (super III)((OH2)(sub 2)(sub 3)(A-alpha-PW9O34)(sub 2)](super 9-), to (Si/AlO2)(super n+) forms an active heterogeneous catalyst, for selective oxidations under mild conditions that has actually been more reactive than the same quantity of the same POM catalyst in solution.

Background: The cortisol awakening response (CAR) has been used as a biomarker of stress response in a multitude of psychological investigations. While a myriad of biochemical responses have been proposed to monitor responses to exercise training, the use of CAR within the exercise and sports sciences is currently limited and is a potentially underutilized variable. Therefore, the purpose of this review was to collate studies that incorporate both exercise and CAR, in an effort to better understand (a) whether CAR is a useful marker for monitoring exercise stress and (b) how CAR may be most appropriately used in future research. Methods: A systematic review of the literature was conducted, following PRISMA guidelines. Searches were conducted using PubMed, SportDISCUS, Scopus, and PsychInfo databases, using search terms related toCAR and exercise and physical activity. Results: 10,292 articles were identified in the initial search, with 32 studies included in the final analysis. No studies investigated the effects of laboratory-controlled exercise on CAR. Variable effects were observed, possibly due to inconsistencies in study design, methodology, population, and CAR analysis. The available literature suggests a threshold of exercise may be required to alter the HPA axis and affect CAR. Moreover, CAR may represent a combination of previous exercise load and upcoming stress, making current interpretation of field-based observational research challenging. Conclusions: More research is needed to fully elucidate the influence of exercise on CAR and address a number of gaps in the literature, including controlling exercise load, consistent sample collection, and CAR calculation and analysis. [ABSTRACT FROM AUTHOR]

This letter demonstrates vertical GaN junction barrier Schottky (JBS) rectifiers fabricated with novel ion implantation techniques. We used two different methods to form the lateral p-n grids below the Schottky contact: 1) Mg implantation into n-GaN to form p-wells and 2) Si implantation into p-GaN to form n-wells. Specific differential ON-resistances ( R \mathrm{\scriptscriptstyle ON} ) of 1.5–2.5 \textm\Omega ~\cdot cm2 and 7–9 \textm\Omega ~\cdot cm2 were obtained in the Mg-implanted and Si-implanted JBS rectifiers, respectively. A breakdown voltage of 500–600 V was achieved in both devices, with a leakage current at high reverse biases at least 100-fold lower than conventional vertical GaN Schottky barrier diodes. The impact of n-well and p-well widths on the R \mathrm{\scriptscriptstyle ON} and BV was investigated. Fast switching capability was also demonstrated. This letter shows the feasibility of forming patterned p-n junctions by novel ion implantation techniques, to enable high-performance vertical GaN power devices. [ABSTRACT FROM AUTHOR]

We seek to optimize Ionic liquids (ILs) for application to redox flow batteries. As part of this effort, we have developed a computational method for suggesting ILs with high conductivity and low viscosity. Since ILs consist of cation-anion pairs, we consider a method for treating ILs as pairs using product descriptors for QSPRs, a concept borrowed from the prediction of protein-protein interactions in bioinformatics. We demonstrate the method by predicting electrical conductivity, viscosity, and melting point on a dataset taken from the ILThermo database on June 18th, 2014. The dataset consists of 4,329 measurements taken from 165 ILs made up of 72 cations and 34 anions. We benchmark our QSPRs on the known values in the dataset then extend our predictions to screen all 2,448 possible cation-anion pairs in the dataset. [ABSTRACT FROM AUTHOR]

The activation of ion implanted p-type dopants in GaN is notoriously difficult as the extremely high temperatures required to activate implanted Mg also damage the GaN crystal. In this paper, we present refinements to our novel annealing process (symmetric multicycle rapid thermal annealing) to reduce surface damage and contamination responsible for elevated leakage currents and non-ideal diode behavior. Furthermore, we apply the technique to Mg-implanted bulk GaN substrates to enable vertical power device structures, demonstrating rectifying p-i-n junctions. In addition, the technique was applied for edge termination in both p-i-n and Schottky barrier diodes, realizing floating guard ring and junction termination extension structures. The processes demonstrated here represents a key enabling step for future GaN-based power devices. [ABSTRACT FROM AUTHOR]

In this paper, electrical characterization results of N-polar GaN high-electron-mobility transistors that have been released from a 6H-SiC wafer and manually transferred to a Si wafer using a novel epitaxial lift-off (ELO) technique are presented. This recently developed ELO method uses a thin sacrificial layer of Nb2N, a hexagonal epitaxial conductor with less than 1% lattice mismatch to 4H- and 6H-SiC, to serve as the template for III-N device heterostructure growth. Measured results of transferred devices indicate that electron transport properties and low power density electrical performance are nominally unchanged relative to values measured before release. This technique has several advantages over competing ELO techniques, such as the well-known smart cut method, including bonding-ready released material with atomically-smooth backsides (≤ 0.5 nm rms), easy substrate reclaim with indefinite recycling potential, and a transfer process that can be performed after full front-side device processing and yield screening has been completed. [ABSTRACT FROM AUTHOR]

Here we investigate the electrochemical activity of metal–organic frameworks (MOFs) as positive electrodes for Na-ion batteries in coin cell configurations. The performance of Fe-MIL-100 material is highly dependent on the choice of sodium salt source, and electrolyte system. The overall capacity fades over many cycles, however the high coulombic efficiency is maintained. This can be correlated with inaccessibility of active sites for Na intercalation, due to the increase of extra carbonaceous material inside the pores. Powder X-ray diffraction via synchrotron data and pair distribution function analyses of the as-made and cycled electrodes reveal the structure maintains the long-range order with progressive cycling. This finding suggests that careful consideration of all variables in battery components, and especially electrolyte selection can lead to greatly improved performances. [ABSTRACT FROM AUTHOR]

Carrier injection by single-photon absorption using ultraviolet optical pulses is used to investigate single-event transients in pristine and proton-irradiated AlGaN/GaN HEMTs. High-precision spatial mapping of defects and traps in AlGaN/GaN HEMT devices identify regions of enhanced SET signals, or “hot spots” that are ascribed to the presence of lattice defects that modify the electric field in the structure. The resulting transient shape and amplitude depend strongly on the specific location of the injected carriers, and vary with changes in gate and drain bias. Proton irradiation significantly alters transient signal shapes, increases the integrated collected charge, and increases density of defects and traps. [ABSTRACT FROM PUBLISHER]

High-temperature X-ray diffraction with concurrent gas chromatography (GC) was used to study cobalt disulfide cathode pellets disassembled from thermal batteries. When CoS2 cathode materials were analyzed in an air environment, oxidation of the K(Br, Cl) salt phase in the cathode led to the formation of K2SO4 that subsequently reacted with the pyrite-type CoS2 phase leading to cathode decomposition between ~260 and 450 °C. Independent thermal analysis experiments, i.e. simultaneous thermogravimetric analysis/differential scanning calorimetry/mass spectrometry (MS), augmented the diffraction results and support the overall picture of CoS2 decomposition. Both gas analysis measurements (i.e. GC and MS) from the independent experiments confirmed the formation of SO2 offgas species during breakdown of the CoS2. In contrast, characterization of the same cathode material under inert conditions showed the presence of CoS2 throughout the entire temperature range of analysis. [ABSTRACT FROM AUTHOR]

Radiation tolerance of AlGaN/GaN high-electron mobility transistors (HEMTs) is studied with 2-MeV protons, up to a fluence of 6 \times 10^14 H+/cm2 (about 200 times of typical Si MOSFET rating). The increase in dynamic ON-resistance ( $R_{{\textit{ONDYN}}})$ after radiation is observed to be much more severe than that of static ON-resistance. Radiation-induced donorlike traps located near the two-dimensional electron gas trap electrons, which is responsible for the phenomenon. Compared with the devices passivated by conventional plasma-enhanced chemical vapor deposition (PECVD) SiN, GaN HEMTs with 10 nm of in situ SiN before the PECVD SiN step demonstrate much less increase in $R_{{\textit{ONDYN}}}$ from 2300% to only 300%. The in situ SiN is believed to reduce the process damage by PECVD, improving radiation tolerance. [ABSTRACT FROM PUBLISHER]

Cancer treatment is associated with adverse changes in strength, body composition, physical function, and quality of life. Exercise training reduces cancer incidence and mortality rates and may offset some of the treatment-related effects. To determine the independent effects of strength training (ST) on the effects of cancer treatment, an initial search was performed in March and then updated in November 2015. Additional articles (ST) on strength, body composition, aerobic capacity, functional assessments, and psychosocial parameters were included. Excluded studies had no objective strength measurement or combined ST with additional exercise. Mean and standard deviations from 39 studies across seven cancer types were extracted for main outcomes. ST-induced change scores with 95 % confidence intervals were calculated and were evaluated with paired t tests, where appropriate. Twenty to fifty percent improvements in maximal strength were observed, indicating that the ST programs were effective. Physical function was also enhanced (7–38 %), although gains were less consistent. Body composition and psychosocial changes were rare, with only a few changes in selected cancer types. As such, ST appears to promote benefits that may be specific to cancer types. Strength was the only consistent outcome that improved in all cancer survivors. However, these gains in strength are still of tremendous importance, given its impact on functionality and quality of life. Several practical considerations for exercise testing, training, and data reporting are presented for consideration to improve the overall depth of the field. [ABSTRACT FROM AUTHOR]

Top-side integration of nanocrystalline diamond films in the fabrication sequence of AlGaN/GaN high electron mobility transistors is demonstrated. Reliable oxygen plasma etching of the diamond capping layer, required for a diamond-before-gate process, was implemented by using a sacrificial SiN 'dummy' gate. Hall characterization showed minimal (∼6%) reduction in sheet carrier density and commensurate increase in sheet resistance, while maintaining mobility and on-state drain current density. Off-state drain current and threshold voltage were increased, likely by fluorination of the AlGaN surface after removal of the sacrificial gate, even though a 20 nm thick Al2O3 layer was used as a SF6-plasma etch stop. Pulsed IDS and on-resistance were improved, indicating that a 10 nm SiN/500 nm NCD could offer improved AlGaN surface passivation compared to a more conventional 100 nm thick PECVD SiN film. [ABSTRACT FROM AUTHOR]

Background. Overtraining (OVT) is a concern for many athletes. Immunological (increased interleukin-6 [IL-6]) and hormonal (increased cortisol [C], decreased free testosterone [fT]) biomarkers have been analyzed during training to detect OVT development. Methods. This study determined if resting levels of salivary IL-6, T, and C change during a pre-season resistance training (RT) program in 20 Division I American football players (mean ± SD: age = 19.1 ± 1.1 years; height = 185.4 ± 6.7 cm; mass = 102.0 ± 22.2 kg; body fat = 14.7 ± 7.6%). 1RM squat, bench press and Olympic-style clean, IL-6, C and T were assessed at baseline (WK1), week 4 (WK4), week 6 (WK6) along with psychological status (PS) to determine affective state. Results. 1RM (bench press: 121.6 ± 36.3 kg vs. 127.4 ± 35.9 kg, squat: 187.2 ± 30.2 kg, 190.9 ± 28.1 kg, clean: 116.8 ± 14.6 kg, vs. 119.2 ± 14.5 kg), IL-6 (1.42 ± 1.77 pg/mL vs. 5.60 ± 12.57 pg/mL) and C (2.57 ± 2.46 nmol/L vs. 5.33 ± 4.94) increased significantly from WK1 to WK6 (p < .05), fT decreased significantly (417.44 ± 83.63 pmol/L vs. 341.10 ± 87.79 pmol/L) from WK1 to WK6 (p < .05). PS was minimally affected during the study. Significant biomarker changes were detected, but no OVT was induced (i.e. performance improved). Conclusion. Therefore, directional changes in these biomarkers may not be sufficiently reflective of OVT in RT programs. [ABSTRACT FROM AUTHOR]

An Mg-implanted p-i-n diode was fabricated and characterized. Mg activation was achieved using the multicycle rapid thermal annealing technique with rapid heating pulses up to 1340 °C. The surface of the implanted GaN after annealing was smooth (0.94 nm RMS roughness) with growth steps evident as characterized by atomic force microscopy. The full width at half-maximum of the implanted GaN E2 Raman mode approaches that of the as-grown GaN after the annealing process, indicating that the annealing process is able to reverse most of the implantation damage. The Mg-implanted p-i-n diode exhibits rectification and a low leakage current of 0.11 μA cm−2 at a bias of −10 V. Under forward bias, light emission was observed from the p-i-n diode. The implantation and activation of Mg in a GaN-based device, demonstrated for the first time in this research, is a key enabling step for future optoelectronic and power electronic devices. Current-voltage characteristics of the Mg-implanted p-i-n diode with an inset of the device schematic. [ABSTRACT FROM AUTHOR]