Layered materials separated from each bulk crystal can be assembled to form a strain-free heterostructure by using the van der Waals interaction. We demonstrated a heterostructure n-channel ...depletion-mode β-Ga2O3 junction field-effect transistor (JFET) through van der Waals bonding with an exfoliated p-WSe2 flake. Typical diode characteristics with a high rectifying ratio of ∼105 were observed in a p-WSe2/n-Ga2O3 heterostructure diode, where WSe2 and β-Ga2O3 were obtained by mechanically exfoliating each crystal. Layered JFETs exhibited an excellent I DS–V DS output as well as I DS–V GS transfer characteristics with a high on/off ratio (∼108) and low subthreshold swing (133 mV/dec). Saturated output currents were observed with a threshold voltage of −5.1 V and a three-terminal breakdown voltage of +144 V. Electrical performances of the fabricated heterostructure JFET were maintained at elevated temperatures with outstanding air stability. Our WSe2–Ga2O3 heterostructure JFET paves the way to the low-dimensional high-power devices, enabling miniaturization of the integrated power electronic systems.
Vanadium dioxide undergoes a reversible metal-insulator phase change near 68°C. This transition is often recognized for its electronic properties; however, the concomitant change in optical ...properties is also attractive. One application is to exploit the optical properties within this transition region to control and tune the refractive index between its insulating and metallic states. To achieve this, we used atomic layer deposition to grow high-quality, low-temperature (≤150°C), ultrathin films of vanadium dioxide on sapphire substrates. Measurements of optical transmittance and reflectance as a function of temperature are then used to create wavelength and temperature dependent models of the complex optical refractive index. Our models create a foundation for developing vanadium dioxide as a tunable refractive index material.
Semiconductor wafer manufacturing relies on the precise control of various performance metrics to ensure the quality and reliability of integrated circuits. In particular, GaN has properties that are ...advantageous for high voltage and high frequency power devices; however, defects in the substrate growth and manufacturing are preventing vertical devices from performing optimally. This paper explores the application of machine learning techniques utilizing data obtained from optical profilometry as input variables to predict the probability of a wafer meeting performance metrics, specifically the breakdown voltage (V
). By incorporating machine learning techniques, it is possible to reliably predict performance metrics that cause devices to fail at low voltage. For diodes that fail at a higher (but still below theoretical) breakdown voltage, alternative inspection methods or a combination of several experimental techniques may be necessary.
A long-standing goal of GaN device research has been the development of a reliable, well-controlled process for p-GaN formation by ion implantation. Results to date have indicated an activation of 1% ...or less using high-temperature rapid thermal annealing (RTA) techniques and coimplantation. Although Mg is a relatively deep acceptor, this is still much less than the theoretically achievable value (8.2% based on the 160 meV acceptor level). A multicycle RTA process is presented that is capable of achieving up to 8% activation of the Mg-implanted GaN. This approaches the theoretical value, and represents a significant step in GaN device research.
Objective
To detail the characteristic traits of children with fetal alcohol spectrum disorders (FASDs) and maternal risk factors in a southeastern U.S. County.
Methods
Independent samples were drawn ...from 2 different cohorts of first‐grade students. All consented children (49.8%) were measured for height, weight, and head circumference, and those ≤ 25th centile entered the study along with a random sample drawn from all enrolled students. Study children were examined for physical growth, dysmorphology, and neurobehavior, and their mothers were interviewed.
Results
Total dysmorphology scores discriminated well the physical traits of children across the FASD continuum: fetal alcohol syndrome (FAS) = 15.8, partial FAS (PFAS) = 10.8, alcohol‐related neurobehavioral disorder (ARND) = 5.2, and typically developing controls = 4.4. Additionally, a neurobehavioral battery distinguished children with each FASD diagnosis from controls. Behavioral problems qualified more children for FASD diagnoses than cognitive traits. Significant proximal maternal risk variables were as follows: reports of prepregnancy drinking, drinking in any trimester, and comorbid use of other drugs in lifetime and during pregnancy, especially alcohol and marijuana (14.9% among mothers of children with FASD vs. 0.4% for controls). Distal maternal risks included reports of other health problems (e.g., depression), living unmarried with a partner during pregnancy, and a lower level of spirituality. Controlling for other drug use during pregnancy, having a child diagnosed with a FASD was 17.5 times greater for women who reported usual consumption of 3 drinks per drinking day prior to pregnancy than for nondrinking mothers (p < 0.001, 95% CI = 5.1 to 59.9). There was no significant difference in the prevalence of FASD by race, Hispanic ethnicity, or socioeconomic status. The prevalence of FASD was not lower than 17.3 per 1,000, and weighted estimated prevalence was 49.0 per 1,000 or 4.9%.
Conclusion
This site had the second lowest rate in the CoFASP study, yet children with FASD are prevalent.
In the Southeastern US site, mothers of children with fetal alcohol spectrum disorders (FASD) were significantly later than mothers of typically developing controls in recognizing their pregnancy. Self‐rated spirituality was significantly lower among mothers of children with FASD, and self‐reported drinking prior to pregnancy was significantly associated with increased odds (7.8‐17.6 times) of bearing a child with FASD than that of women reporting no drinking. This site had the second lowest weighted prevalence of FASD of the four Collaboration on Fetal Alcohol Spectrum Disorders Prevalence (CoFASP) sites of 4.9%.
The osmotic dehydration of cherry tomatoes in complex solution of salt and sugar was studied by using the response surface methodology while the approach of desirability was applied to define the ...best operative conditions taking into account contemporaneously several quality parameters. Water activity, moisture content, consistency and red index (a*) were the only parameters which showed significant changes as a function of the independent variables. The changes of these attributes were well modeled obtaining in all cases a correlation coefficients greater than 0.94; treatment time and the mass fraction of sucrose were the most important variables for reducing water activity and moisture content while for consistency and color, the mass fractions of sucrose and sodium chloride were the most important processing variables. Desirability approach allowed defining the best operative conditions; specifically, when the overall quality of osmotized cherry tomatoes was considered as equilibrium of values of aw, consistency and red index, a maximum desirability of 0.736 could be obtained by using mass fractions of sucrose and NaCl respectively of 55.62 and 2.45% and a treatment time of 22 h.
•The osmotic dehydration of cherry tomatoes in solution of sugar and salt was studied.•Response surface methodology (RSM) enabled to define the effect process variables on the quality of samples.•The optimization of multiple responses was obtained by desirability approach.•The mass fraction of osmotic agents exhibited the higher effect on the quality of samples.•A water activity reduction until 0.935 was obtained maintaining sensorial properties of fresh tomatoes.
It is well known that hepatocellular carcinoma (HCC) is an arginine auxotroph due to argininosuccinate synthetase I deficiency. This study's purpose was to evaluate the effects of pegylated arginine ...deiminase (ADI) in terms of toxicity, tumor response, alpha-fetoprotein (AFP) levels, and serum arginine levels.
Eighty patients were randomly assigned to receive either 80 IU/m(2) or 160 IU/m(2) of ADI weekly for up to 6 months. Adverse events, serum arginine, AFP levels, and antibody production against ADI were measured on a regular basis. In addition, disease response and time to progression according to the Response Evaluation Criteria in Solid Tumors (RECIST) and survival rates were evaluated.
Four patients were excluded from the survival analysis because they developed exclusion criteria after randomization, but before first treatment. The number of patients in the two cohorts were similar (n = 37 in the low-dose cohort, n = 39 in the high-dose cohort). Mean (+/-SE) survival for all subjects was 15.8 months (474 days +/- 39 days) from time of diagnosis of unresectable disease. Arginine levels remained below baseline for 50 days while antibodies against ADI reached a plateau at approximately the same time. There were no deaths attributed to ADI treatment. Only two patients were withdrawn for immunogenic-related adverse events. Grade 2, 3, or 4 toxicities were recorded in 92, 19, and 0 patients, respectively.
Pegylated ADI is a promising drug that capitalizes on a significant enzymatic deficiency in HCC. It is safe, well tolerated, and may benefit patients with unresectable HCC.
Patients living with multidrug-resistant (MDR) HIV have limited antiretroviral regimen options that provide durable viral suppression. Lenacapavir is a novel first-in-class inhibitor of HIV-1 capsid ...function with efficacy at various stages of the viral life cycle, and it is indicated for the treatment of MDR HIV-1 infection in combination with optimized background antiretroviral therapy. The favourable pharmacokinetic profile supports an every sixth month dosing interval of subcutaneous lenacapavir after an initial oral loading dose, which may advocate for continued adherence to antiretroviral therapy (ART) through the reduction of daily pill burden. The role of lenacapavir in promoting virologic suppression has been studied in patients with MDR HIV-1 on failing ART at baseline. Lenacapavir was well tolerated in clinical trials with the most common adverse effects including mild to moderate injection site reactions, gastrointestinal symptoms, and headache. Substitutions on the capsid molecule may confer resistance to lenacapavir by changing the binding potential. Cross-resistance to other antiretrovirals has not been observed. The unique mechanism of action, pharmacokinetics, and safety and efficacy of lenacapavir support its use for the management of MDR HIV-1 infection. Current studies are ongoing to evaluate the potential use of subcutaneous lenacapavir for pre-exposure prophylaxis (PrEP). Future studies will confirm the long-term clinical safety, efficacy, and resistance data for lenacapavir.
AlGaN/GaN high electron mobility transistors grown on Si, SiC, and sapphire substrates were exposed to 2-MeV proton irradiation in incremental fluences up to 6 × 10 14 cm -2 . The devices were ...characterized initially and after each irradiation by Hall and dc I-V measurements to probe the mechanisms associated with radiation-induced degradation and failure. It was determined that defects created at the AlGaN/GaN interface introduce scattering centers near the two-dimensional electron gas (2DEG), which result in degraded mobility. Additionally, charged traps in the structure serve to screen the 2DEG resulting in reduced sheet carrier density. These two effects are responsible for degraded I-V behavior, including reduced saturation current and transconductance, increased ON-resistance, and positive threshold voltage shift. Interestingly, the sample with the most pre-existing defects was the most tolerant of radiation-induced damage.
To improve the manufacturing process of GaN wafers, inexpensive wafer screening techniques are required to both provide feedback to the manufacturing process and prevent fabrication on low quality or ...defective wafers, thus reducing costs resulting from wasted processing effort. Many of the wafer scale characterization techniques-including optical profilometry-produce difficult to interpret results, while models using classical programming techniques require laborious translation of the human-generated data interpretation methodology. Alternatively, machine learning techniques are effective at producing such models if sufficient data is available. For this research project, we fabricated over 6000 vertical PiN GaN diodes across 10 wafers. Using low resolution wafer scale optical profilometry data taken before fabrication, we successfully trained four different machine learning models. All models predict device pass and fail with 70-75% accuracy, and the wafer yield can be predicted within 15% error on the majority of wafers.
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