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β-Ga 2 O 3 is a promising material for next-generation power devices because of its ultra-wide bandgap, the commercial availability of bulk substrates, epitaxial growth, and ease of n-type doping. To fully exploit its potential, it is critical to establish fabrication processes to form low-resistance ohmic contacts with excellent long-term stability. Due to upward band bending and unavoidable redox reactions occurring at the contact interface, making a good ohmic contact to gallium oxide can be challenging. Herein, we use a process-structure-property approach to systematically review the reported processes for ohmic contact formation on gallium oxide, the contact microstructure, and the resulting electrical properties including charge transport physics. Furthermore, we describe the present evidence for ohmic contact stability under accelerated aging. Using thermodynamic assessment, we propose alternate ohmic contact materials candidates. Finally, we identify gaps in the scientific knowledge on ohmic contacts to Ga 2 O 3 and highlight opportunities for future investigations. Graphic Abstract

The performance of silicon complementary metal–oxide–semiconductor integrated circuits can be enhanced through the monolithic three-dimensional integration of additional device layers. For example, silicon integrated circuits operate at low voltages (around 1 V) and high-voltage handling capabilities could be provided by monolithically integrating thin-film transistors. Here we show that high-voltage amorphous oxide semiconductor thin-film transistors can be integrated on top of a silicon integrated circuit containing 100-nm-node fin field-effect transistors using an in-air solution process. To solve the problem of voltage mismatch between these two device layers, we use a top Schottky, bottom ohmic contact structure to reduce the amorphous oxide semiconductor circuit switching voltage. These contacts are used to form Schottky-gated thin-film transistors and vertical thin-film diodes with excellent switching performance. As a result, we can create high-voltage amorphous oxide semiconductor circuits with switching voltages less than 1.2 V that can be directly integrated with silicon integrated circuits. High-voltage amorphous oxide semiconductor thin-film transistors can be integrated on top of a silicon integrated circuit containing 100-nm-node fin field-effect transistors using an in-air solution process.

PurposeDefects in the homologous recombination (HR) DNA repair pathway sensitize tumors to therapeutics that target this pathway. A significant proportion of triple-negative breast cancers (TNBC) carry HR defects. The HRD assay is highly associated with sensitivity to neoadjuvant platinum-based chemotherapy in TNBC. Standard chemotherapy consists of some combination of an anthracycline, cyclophosphamide, and taxane. This study assesses the association of HR deficiency status with response to standard neoadjuvant chemotherapy in TNBC or BRCA1/2 mutation-associated breast cancer.MethodsTumor samples were retrospectively obtained from 45 TNBC patients and 2 BRCA1/2 mutant, hormone receptor-positive/HER2-negative breast cancer patients who received anthracycline- and/or taxane-based neoadjuvant chemotherapy at Stanford University or Cedars-Sinai Medical Centers. The HRD score and tumor BRCA1/2 mutation status were determined from baseline tumor biopsies. HR deficient tumors were those with a HRD score of ≥ 42 or a tumor BRCA1/2 mutation. Response was categorized by the residual cancer burden (RCB) index.ResultsHR deficient patients were more likely to achieve a pathologic complete response (pCR) compared with non-deficient patients (OR 13.06, CI 1.52–11.241, p = 0.0028). Among BRCA1/2 mutation wild-type patients, HR deficient patients were more likely to achieve a pCR (OR 16, 95% CI 1.65–160.41, p = 0.0041) compared with HR non-deficient patients. Further, HRD scores were highly concordant pre- and post-therapy (Spearman correlation > 99%).ConclusionsHR deficiency status is significantly associated with response to standard neoadjuvant chemotherapy in TNBC. This observation is consistent with the mechanisms of action of doxorubicin and cyclophosphamide as DNA damaging agents.

In 2015, there was a large outbreak of Zika virus (ZIKV) in Brazil. Despite its relatively mild impact on healthy adults, ZIKV infection during pregnancy has been associated with severe birth defects. Currently, there is no ZIKV vaccine available, but several vaccine candidates based on the ZIKV membrane (M) and envelope (Env) structural proteins showed promising results in preclinical and clinical studies. Here, the immunogenicity and protective efficacy of a non-replicating adenoviral vector type 26 (Ad26) that encodes the ZIKV M-Env antigens (Ad26.ZIKV.M-Env) was evaluated in mice and non-human primates (NHP). Ad26.ZIKV.M-Env induced strong and durable cellular and humoral immune responses in preclinical models. Humoral responses were characterized by Env-binding and ZIKV neutralizing antibody responses while cellular responses were characterized by ZIKV reactive CD4+ and CD8+ T cells. Importantly, a single immunization with a very low dose of 4x107 vp of Ad26.ZIKV.M-Env protected mice from ZIKV challenge. In NHP, a single immunization with a typical human dose of 1x1011 vp of Ad26.ZIKV.M-Env also induced Env-binding and ZIKV neutralizing antibodies and Env and M specific cellular immune responses that associated with complete protection against viremia from ZIKV challenge as measured in plasma and other body fluids. Together these data provide the rationale to progress the Ad26.ZIKV.M-Env candidate vaccine to clinical testing.

As gallium oxide-based heterojunction devices gain prominence, low-resistance contacts to aluminum gallium oxide material are of increasing importance for high performance and access to modulation doped layers. Here, the activation of ion-implanted silicon donors is investigated as a function of donor density from 5 × 1018 cm−3 to 1 × 1020 cm−3, activation anneal duration from 6 s to 600 s, and activation temperature from 900°C to 1140°C. Importantly, ohmic behavior was achievable across a reasonably wide process window at moderate to high doping concentrations. Specific contact resistance of 1 × 10−3 Ω cm2 and sheet resistance of 2.8 kΩ/□ were achieved for a 60 nm-deep 1 × 1020 cm−3 box implant after activation at 1000°C for 6 s with standard Ti/Au contacts. Under these conditions, an activation efficiency of 7% was observed with Hall mobility of ~32 cm2/Vs. Furthermore, we demonstrate a Schottky diode formed of implanted material with a rectification ratio > 106 and further confirm the Hall carrier density results using capacitance–voltage profiling analysis. Finally, we show the significant impact of anneal duration and the potential for deleterious over-annealing which reduces the active carrier density, mobility, and resultant material conductivity.

Zinc oxide-based transparent amorphous oxide semiconductors (TAOS) are strong contenders to replace amorphous and polycrystalline silicon for large area display backplanes due to their high electron mobility. To enable future roll-to-roll printed electronics, solution-processed fabrication methods are needed. Here, we use low-temperature measurements from 77 to 300 K to quantitatively compare charge transport mechanisms and band-tail density of states of solution-processed zinc tin oxide (ZTO) thin film transistors fabricated with different film composition and annealing temperature. The devices exhibit percolation conduction with Fermi level pinning at high charge carrier concentrations. The shape and energy levels of band-tail states can be engineered by process and stoichiometry. For optimal amorphous ZTO film with Zn:Sn ink ratio of 7:3 and annealing temperature of 480 °C, the band structure exhibits Arrhenius and percolation energy values of 7 and 3 meV, respectively, better than those measured by others for vacuum-processed TAOS films, showing the potential of solution processing.

An HIV therapeutic that would give long-term remission without sustained antiretroviral therapy (ART) is a long-term goal. Byrareddy et al. [ Science 354 , 197 (2016)] reported that treating simian immunodeficiency virus (SIV)–positive macaques with an antibody against integrin α 4 β 7 during and after ART results in sustained virologic control after stopping all treatment. Three studies in this issue question the reproducibility of that result. Di Mascio et al. sequenced the virus used in the 2016 study and found that it was a variant with a stop codon in the nef gene rather than a wild-type virus. Abbink et al. used the same antibody for α 4 β 7 as before but tested control of a more commonly used pathogenic virus. Iwamato et al. used the same nef -stop virus as in the earlier paper but combined the antibody against the integrin with an antibody against the SIV envelope glycoprotein, which also blocks viral binding of the integrin. None of these three new studies found that treating with the antibody had any effect on virologic control after stopping ART treatment. Science , this issue p. 1025 , p. 1029 , p. 1033 Anti-α 4 β 7 treatment did not have a detectable impact on plasma viremia, tissue viral load, or CD4 + T cell counts. Sustained virologic control of human immunodeficiency virus type 1 (HIV-1) infection after discontinuation of antiretroviral therapy (ART) is a major goal of the HIV-1 cure field. A recent study reported that administration of an antibody against α 4 β 7 induced durable virologic control after ART discontinuation in 100% of rhesus macaques infected with an attenuated strain of simian immunodeficiency virus (SIV) containing a stop codon in nef . We performed similar studies in 50 rhesus macaques infected with wild-type, pathogenic SIVmac251. In animals that initiated ART during either acute or chronic infection, anti-α 4 β 7 antibody infusion had no detectable effect on the viral reservoir or viral rebound after ART discontinuation. These data demonstrate that anti-α 4 β 7 antibody administration did not provide therapeutic efficacy in the model of pathogenic SIVmac251 infection of rhesus macaques.

Sustained virologic control of human immunodeficiency virus type 1 (HIV-1) infection after discontinuation of antiretroviral therapy (ART) is a major goal of the HIV-1 cure field. A recent study reported that administration of an antibody against α4β7 induced durable virologic control after ART discontinuation in 100% of rhesus macaques infected with an attenuated strain of simian immunodeficiency virus (SIV) containing a stop codon in nef. We performed similar studies in 50 rhesus macaques infected with wild-type, pathogenic SIVmac251. In animals that initiated ART during either acute or chronic infection, anti-α4β7 antibody infusion had no detectable effect on the viral reservoir or viral rebound after ART discontinuation. These data demonstrate that anti-α4β7 antibody administration did not provide therapeutic efficacy in the model of pathogenic SIVmac251 infection of rhesus macaques.

Peterson considers Brad S. Gregory's Rebel in the Ranks: Martin Luther, the Reformation and the Conflicts that Continue to Shape Our World from the perspective of an undergraduate student choosing it as a source for a project. Undergraduate students are apt to choose this work because of the more relaxed manner in which it is written and the broad coverage of the era. This work does not imaginatively reinterpret the Reformer but communicates topics and personalities of the Reformation in an accessible way to those new to the era and challenges them to consider the unintended impacts of the Reformation and Luther's theme of sola scriptura.

Robust redhorse (Moxostoma robustum) is a rare riverine sucker for which life history information is scarce. Spawning occurs over loose gravel substrate and eggs and larvae may be adversely affected by fine sediments among the gravel. A 2-year study was conducted to determine the threshold at which fine sediments are detrimental to successful egg incubation and larval emergence. Year 1 gravel treatments contained 0, 25, 50, and 75% fine sediments. Mean survival during Year 1 ranged from 63.5% in the 0% fine sediment treatment to 0% in the 75% fine sediment treatment. The results also indicated an adverse affect threshold between 0 and 25% fine sediment. Year 2 gravel treatments contained 0, 5, 10, 15, 20, and 25% fine sediments. Mean survival during Year 2 ranged from 69.8% in the 0% treatment to 9.1% in the 25% treatment. Year 2 results also identified the 15% fine sediment treatment as the threshold at which survival began to decline. Substrates at one known spawning area used by robust redhorse typically contain 25 to 50% fine sediment, but the spawning act cleans some fines from the egg pocket. Whether the “cleaning” that results from the spawning act reduces the fines sufficiently to avoid adverse effects is unknown. According to our results, survival rates of robust redhorse eggs and larvae are predicted to be about 8.0% or less when fine sediment is >25%.