Magnetoresistance of doped silicon

We have performed longitudinal magnetoresistance measurements on heavily n-doped silicon for donor concentrations exceeding the critical value for the metal-non-metal transition. The results are compared to those from a many-body theory where the donor-electrons are assumed to reside at the bottom of the many-valley conduction band of the host. Good qualitative agreement between theory and experiment is obtained.Comment: 7 pages, 8 figure

Heavily n-doped Ge : low-temperature magnetoresistance properties on the metallic side of the metal–nonmetal transition

We report here an experimental and theoretical study on the magnetoresistance properties of heavily phosphorous doped germanium on the metallic side of the metal–nonmetal transition. An anomalous regime, formed by negative values of the magnetoresistance, was observed by performing low-temperature measurements and explained within the generalized Drude model, due to the many-body effects. It reveals a key mechanism behind the magnetoresistance properties at low temperatures and, therefore, constitutes a path to its manipulation in such materials of great interest in fundamental physics and technological applications

Highly Photocatalytic Titanium Oxide/Carbon Nitride Heterojunctions Obtained via Dual Asymmetric Centrifugation

In this work dual asymmetric centrifugation technique was applied to obtain new TiO2/carbon nitride heterojunctions (TiO2/g-C3N4) with high photocatalytic performance. Materials were obtained from TiO2 and g-C3N4, with an optimal mass ratio of 1.0:0.1 for achieving the highest photocatalytic activity in dyes degradation. The TiO2/g-C3N4 (1.0/0.1) photocatalyst was characterized via X-ray diffraction, confirming the crystalline phases and chemical composition of the material. UV–VIS spectroscopy data showed an increase in the visible light absorption, indicating an effective interaction between the heterojunction components. XPS data showed the formation of Ti3+ ions and oxygen vacancies, boosting the photocatalytic process. The TiO2/g-C3N4 (1.0/0.1) showed the highest photocatalytic performance degrading 99.9 % of rhodamine B and 99.6 % of methylene blue in 60 min under LED light irradiation. Radicals trapping experiments indicated O2–● radicals as the major photoactive species, through a Z-scheme type mechanism. The product of RhB photodegradation did not show toxicity to Artemia fransciscana larvae

Serum biomarkers associated with SARS-CoV-2 severity

Immunity with SARS-CoV-2 infection during the acute phase is not sufficiently well understood to differentiate mild from severe cases and identify prognostic markers. We evaluated the immune response profile using a total of 71 biomarkers in sera from patients with SARS-CoV-2 infection, confirmed by RT-PCR and controls. We correlated biological marker levels with negative control (C) asymptomatic (A), nonhospitalized (mild cases-M), and hospitalized (severe cases-S) groups. Among angiogenesis markers, we identified biomarkers that were more frequently elevated in severe cases when compared to the other groups (C, A, and M). Among cardiovascular diseases, there were biomarkers with differences between the groups, with D-dimer, GDF-15, and sICAM-1 higher in the S group. The levels of the biomarkers Myoglobin and P-Selectin were lower among patients in group M compared to those in groups S and A. Important differences in cytokines and chemokines according to the clinical course were identified. Severe cases presented altered levels when compared to group C. This study helps to characterize biological markers related to angiogenesis, growth factors, heart disease, and cytokine/chemokine production in individuals infected with SARS-CoV-2, offering prognostic signatures and a basis for understanding the biological factors in disease severity

HIV-1 and HIV-2 prevalence, risk factors and birth outcomes among pregnant women in Bissau, Guinea-Bissau: a retrospective cross-sectional hospital study

The human immunodeficiency virus (HIV) remains a leading cause of maternal morbidity and mortality in Sub-Saharan Africa. Prevention of mother-to-child transmission (PMTCT) has proven an effective strategy to end paediatric infections and ensure HIV-infected mothers access treatment. Based on cross-sectional data collected from June 2008 to May 2013, we assessed changes in HIV prevalence, risk factors for HIV, provision of PMTCT antiretroviral treatment (ART), and the association between HIV infection, birth outcomes and maternal characteristics at the Simão Mendes National Hospital, Guinea-Bissau’s largest maternity ward. Among 24,107 women, the HIV prevalence was 3.3% for HIV-1, 0.8% for HIV-2 and 0.9% for HIV-1/2. A significant decline in HIV-1, HIV-2, and HIV-1/2 prevalence was observed over time. HIV infection was associated with age and ethnicity. A total of 85% of HIV-infected women received ART as part of PMTCT, yet overall treatment coverage during labour and delivery declined significantly for both mothers and infants. Twenty-two percent of infants did not receive treatment, and 67% of HIV-2-infected mothers and 77% of their infants received ineffective non-nucleoside reverse transcriptase inhibitors for PMTCT. Maternal HIV was associated with low birth weight but not stillbirth. Inadequate continuity of care and ART coverage present challenges to optimal PMTCT in Guinea-Bissau