Flow and Fracture Behaviour of Tungsten Fiber Reinforced Superalloy Composites-Effect Of Specimen Geometry

The influence of aspect ratio (i.e. width to height ratio) of test specimens on the flow and fracture behaviour of fiber reinforced composites is herein examined. The composite material was prepared by isostatic pressing of a Mar-M200 nickel-base superallov matrix reinforced with 40% tungsten wires. I. niaxial compression forging was performed at a constant true strain rate of 3x10^ S , with temperature as parameter. The aspect ratio (wo/ho) of test blanks was made to vary between 0.3 and 3, loading being always normal to the direction of wire alignment. It is herein established that peak flow stress values of composite material increase significantly with rising aspect ratio while severity of damage is shown to decrease. Furthermore, it is found that the fracture pattern is also influenced by specimen geometry. This may he attributed to some favourable effect of a hydrostatic compressive stress component which seeks to retard void formation and growth. Relevant practical implications are discussed

STEROLS BIOACTIVITY OF RUTA GRAVEOLENS L. AND MURRAYA PANICULATA L.

Objective: Ruta graveolens L. (R. graveolens) and Murraya paniculata L. (M. paniculata) are medicinal plants belonging to Rutaceae family have many uses in traditional medicine. The aim of the present study was to investigate sterols bioactivity of the two Rutaceae plant leaves.Methods: Sterols of the two Rutaceae plant leaves were identified using GC/MS. The antioxidant activities of the sterols of these herbs were evaluated by three different methods; free radical scavenging using 2,2′-Azino-bis (3-ethylbenzthiazoline-6-sulfonic acid) (ABTS), 1,1-Diphenyl-2-picryl-hydrazyl (DPPH) and total antioxidant activity. The anticancer activity of the sterols was determined by MTT assay against colorectal cancer HCT116, breast cancer MCF7, liver cancer HepG2 and lung cancer A549 cell lines. Anti-inflammatory activity was evaluated using albumin denaturation assay and antiviral activities against H5N1 virus were carried out using plaque reduction assay.Results: GC/MS assay showed β-Sitosterol (36%) as the most abundant sterols of R. graveolens followed by stigmasterol (18%), while stigmasterol (25.2%) was the most abundant one of M. paniculata steroids. The anti-inflammatory potential of R. graveolens steroids was significantly higher than that of diclofenac sodium (standard drug). M. paniculata sterols have higher antiviral activity (IC50= 0.15 of µg/ml) than R. graveolens sterols (IC50= 7.8 of µg/ml). The sterols of R. graveolens showed anticancer activity against MCF7 and A549 cells with inhibition 84.3 and 81%, at 100 µg/ml respectively. While M. paniculata sterols showed 77.3% inhibition against A549 cells.Conclusion: The current study suggests that the sterols of M. paniculata have more anti-viral activity than R. graveolens sterols which showed more anticancer and anti-inflammatory activities

Rapid evolution of A(H5N1) influenza viruses after intercontinental spread to North America

Highly pathogenic avian influenza A(H5N1) viruses of clade 2.3.4.4b underwent an explosive geographic expansion in 2021 among wild birds and domestic poultry across Asia, Europe, and Africa. By the end of 2021, 2.3.4.4b viruses were detected in North America, signifying further intercontinental spread. Here we show that the western movement of clade 2.3.4.4b was quickly followed by reassortment with viruses circulating in wild birds in North America, resulting in the acquisition of different combinations of ribonucleoprotein genes. These reassortant A(H5N1) viruses are genotypically and phenotypically diverse, with many causing severe disease with dramatic neurologic involvement in mammals. The proclivity of the current A(H5N1) 2.3.4.4b virus lineage to reassort and target the central nervous system warrants concerted planning to combat the spread and evolution of the virus within the continent and to mitigate the impact of a potential influenza pandemic that could originate from similar A(H5N1) reassortants

Accelerated evolution of SARS-CoV-2 in free-ranging white-tailed deer

The zoonotic origin of the COVID-19 pandemic virus highlights the need to fill the vast gaps in our knowledge of SARS-CoV-2 ecology and evolution in non-human hosts. Here, we detected that SARS-CoV-2 was introduced from humans into white-tailed deer more than 30 times in Ohio, USA during November 2021-March 2022. Subsequently, deer-to-deer transmission persisted for 2–8 months, disseminating across hundreds of kilometers. Newly developed Bayesian phylogenetic methods quantified how SARS-CoV-2 evolution is not only three-times faster in white-tailed deer compared to the rate observed in humans but also driven by different mutational biases and selection pressures. The long-term effect of this accelerated evolutionary rate remains to be seen as no critical phenotypic changes were observed in our animal models using white-tailed deer origin viruses. Still, SARS-CoV-2 has transmitted in white-tailed deer populations for a relatively short duration, and the risk of future changes may have serious consequences for humans and livestock

The evolving SARS-CoV-2 epidemic in Africa: insights from rapidly expanding genomic surveillance

Investment in severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) sequencing in Africa over the past year has led to a major increase in the number of sequences that have been generated and used to track the pandemic on the continent, a number that now exceeds 100,000 genomes. Our results show an increase in the number of African countries that are able to sequence domestically and highlight that local sequencing enables faster turnaround times and more-regular routine surveillance. Despite limitations of low testing proportions, findings from this genomic surveillance study underscore the heterogeneous nature of the pandemic and illuminate the distinct dispersal dynamics of variants of concern—particularly Alpha, Beta, Delta, and Omicron—on the continent. Sustained investment for diagnostics and genomic surveillance in Africa is needed as the virus continues to evolve while the continent faces many emerging and reemerging infectious disease threats. These investments are crucial for pandemic preparedness and response and will serve the health of the continent well into the 21st century

The evolving SARS-CoV-2 epidemic in Africa: insights from rapidly expanding genomic surveillance

Investment in SARS-CoV-2 sequencing in Africa over the past year has led to a major increase in the number of sequences generated, now exceeding 100,000 genomes, used to track the pandemic on the continent. Our results show an increase in the number of African countries able to sequence domestically, and highlight that local sequencing enables faster turnaround time and more regular routine surveillance. Despite limitations of low testing proportions, findings from this genomic surveillance study underscore the heterogeneous nature of the pandemic and shed light on the distinct dispersal dynamics of Variants of Concern, particularly Alpha, Beta, Delta, and Omicron, on the continent. Sustained investment for diagnostics and genomic surveillance in Africa is needed as the virus continues to evolve, while the continent faces many emerging and re-emerging infectious disease threats. These investments are crucial for pandemic preparedness and response and will serve the health of the continent well into the 21st century