Single-Polymer Composites (SPCs) : Status and Future Trends

Preparation, properties and applications of single-polymer composites (SPCs), representing an emerging family within the polymeric composite materials, have been surveyed. SPCs were classified in respect to their composition (one- and two-constituents), and preforms (non-consolidated and consolidated). SPCs composed of amorphous or semicrystalline matrices and semicrystalline reinforcements were considered. Methods to widen the temperature difference between the matrix- and reinforcement-giving materials of the same polymer (one-constituent) or same polymer type (two-constituent approach) have been introduced and discussed. Special attention was paid to the unsolved questions related to the interface/interphase in SPCs. It was emphasized that the development of SPCs is fuelled by the need of engineering parts in different applications which have low density and “ultimate” recyclability (i.e. reprocessing via remelting). Recent development of SPCs is supported by novel preform preparation, consolidation and production possibilities

Risk factors for Coronavirus disease 2019 (Covid-19) death in a population cohort study from the Western Cape province, South Africa

Risk factors for coronavirus disease 2019 (COVID-19) death in sub-Saharan Africa and the effects of human immunodeficiency virus (HIV) and tuberculosis on COVID-19 outcomes are unknown. We conducted a population cohort study using linked data from adults attending public-sector health facilities in the Western Cape, South Africa. We used Cox proportional hazards models, adjusted for age, sex, location, and comorbidities, to examine the associations between HIV, tuberculosis, and COVID-19 death from 1 March to 9 June 2020 among (1) public-sector “active patients” (≥1 visit in the 3 years before March 2020); (2) laboratory-diagnosed COVID-19 cases; and (3) hospitalized COVID-19 cases. We calculated the standardized mortality ratio (SMR) for COVID-19, comparing adults living with and without HIV using modeled population estimates.Among 3 460 932 patients (16% living with HIV), 22 308 were diagnosed with COVID-19, of whom 625 died. COVID19 death was associated with male sex, increasing age, diabetes, hypertension, and chronic kidney disease. HIV was associated with COVID-19 mortality (adjusted hazard ratio [aHR], 2.14; 95% confidence interval [CI], 1.70–2.70), with similar risks across strata of viral loads and immunosuppression. Current and previous diagnoses of tuberculosis were associated with COVID-19 death (aHR, 2.70 [95% CI, 1.81–4.04] and 1.51 [95% CI, 1.18–1.93], respectively). The SMR for COVID-19 death associated with HIV was 2.39 (95% CI, 1.96–2.86); population attributable fraction 8.5% (95% CI, 6.1–11.1)

Mitogenomics and the Global Dispersion of <i>Vespula germanica</i>: A Case Study from South Africa Shows Evidence for Two Separate Invasion Events

Vespula germanica is currently present in all major world regions outside its native Northern Hemisphere range and poses a biological threat to the invaded ecosystems. The genetic diversity of the species is poorly described in both the native and invaded ranges, thus hampering insights into possible mechanisms of invasion. In South Africa, V. germanica was first detected in 1972, and a recent study concluded that one large or several independent invasion events had occurred. However, the high number of low-frequency haplotypes reported therein raised doubts about the quality of the data. In this study, we reassessed the haplotype diversity of V. germanica in South Africa under improved methodological conditions. New mitochondrial markers were developed using complete mitochondrial genomes of V. germanica that allowed the identification of polymorphic regions and the design of robust species-specific primers. Contrary to two previous studies, only two mitochondrial haplotypes were found in South Africa despite almost doubling the number of sampled nests. It is likely that that the number of haplotypes previously reported was overestimated due to the miscalling of nucleotide positions in the electropherograms. Furthermore, the two haplotypes found have contrasting geographic distributions, which supports the known invasion history for this species. Availability of complete mitochondrial genomes for selection of polymorphic regions and design of robust species-specific primers improved the accuracy of the assessment of V. germanica diversity in South Africa. This approach will also be valuable for studying invasive wasp populations of this and other species globally