Fresh Molecular Look at Calcite-Brine Nanoconfined Interfaces

Calcite-fluid interface plays a central role in geochemical, synthetic, and biological crystal growth. The ionic nature of the calcite surface can modify the fluid-solid interaction and the fluid properties under spatial confinement and can also influence the adsorption of chemical species. We investigate the structure of the solvent and ions (Na, Cl, and Ca) at the calcite-aqueous solution interface under confinement and how such environment modifies the properties of water. To properly investigate the system, molecular dynamics simulations were employed to analyze the hydrogen bond network and to calculate NMR relaxation times. Here, we provide a new insight with additional atomistically detailed analysis by relating the topology of the hydrogen bond network with the dynamical properties in nanoconfinement interfaces. We have shown that the strong geometrical constraints and the presence of ions do influence the hydrogen bond network, resulting in more extended geodesic paths. Hydrogen bond branches connect low to high dynamics molecules across the pore and hence may explain the gluelike mechanical properties observed in the confinement environment. Moreover, we showed that the surface water observed at the calcite interface is characterized by slow transversal spin relaxation time (T2) and highly coordinated water molecules. The physical and electrostatic barrier emerged from the epitaxial ordering of water results in a particular ionic distribution, which can prevent the direct adsorption of a variety of chemical species. The implications of our results delineate important contributions to the current understanding of crystallization and biomineralization processes.Fil: Kirch, Alexsandro. Universidade de Sao Paulo; BrasilFil: Mutisya, Sylvia Mueni. Universidade Federal Do Abc; BrasilFil: Sanchez, Veronica Muriel. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Centro de Simulación Computacional para Aplicaciones Tecnológicas; Argentina. Universidad Nacional de San Martín. Escuela de Ciencia y Tecnología; ArgentinaFil: de Almeida, James Moraes. Universidade de Sao Paulo; BrasilFil: Miranda, Caetano Rodrigues. Universidade de Sao Paulo; Brasi

Isolation and phylogenetic characterization of arboviruses circulating among phlebotomine sandflies in parts of North Rift, Kenya

BackgroundUntil recently, arbovirus surveillance is mainly focused on mosquito and tick vectors, resulting in the discovery of several mosquito- and tick-borne arboviruses. However, the role of sandflies in arbovirus transmission and disease has remained largely unexplored. This study sought to isolate and characterize arboviruses from phlebotomine sandflies from selected pastoral ecozones in the North Rift region of Kenya.MethodsSandflies were collected from selected sites in North Rift Kenya between 2015 and 2018. They were sorted and pooled by sex, site, and collection date. The pools were homogenized and inoculated onto Vero cells for virus isolation. The positive pools were analyzed by polymerase chain reaction targeting different arboviruses. The isolates were further characterized by high-throughput sequencing using Illumina Miseq platform.ResultsApproximately 28,226 sandflies translating to 824 pools were sampled from the selected regions. A total of 11 showed reproducible cytopathic effects on Vero cells. We identified five arboviruses: sindbis (n = 4) from Kacheliba and Baringo, Chandipura (n = 4) from Turkana and Baringo, Koutango (n = 1) and Ntepes (n = 1) from Baringo, and Bogoria (n = 1) from Kacheliba. The percent identities of the identified viruses were approximately 80% to 98% compared to known viruses in GenBank, suggesting that some of them could be novel viruses.ConclusionThis study successfully isolated and characterized five arboviruses from sandflies. The findings suggest that sandflies are potential hosts of a wide range of arboviruses and are therefore important vectors to consider in arbovirus surveillance and evaluated for their ability to transmit them. Further studies are needed to determine the public health importance and extent of exposure of these viruses to humans and livestock populations

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

INTRODUCTION Investment in Africa over the past year with regard to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) sequencing has led to a massive increase in the number of sequences, which, to date, exceeds 100,000 sequences generated to track the pandemic on the continent. These sequences have profoundly affected how public health officials in Africa have navigated the COVID-19 pandemic. RATIONALE We demonstrate how the first 100,000 SARS-CoV-2 sequences from Africa have helped monitor the epidemic on the continent, how genomic surveillance expanded over the course of the pandemic, and how we adapted our sequencing methods to deal with an evolving virus. Finally, we also examine how viral lineages have spread across the continent in a phylogeographic framework to gain insights into the underlying temporal and spatial transmission dynamics for several variants of concern (VOCs). RESULTS Our results indicate that the number of countries in Africa that can sequence the virus within their own borders is growing and that this is coupled with a shorter turnaround time from the time of sampling to sequence submission. Ongoing evolution necessitated the continual updating of primer sets, and, as a result, eight primer sets were designed in tandem with viral evolution and used to ensure effective sequencing of the virus. The pandemic unfolded through multiple waves of infection that were each driven by distinct genetic lineages, with B.1-like ancestral strains associated with the first pandemic wave of infections in 2020. Successive waves on the continent were fueled by different VOCs, with Alpha and Beta cocirculating in distinct spatial patterns during the second wave and Delta and Omicron affecting the whole continent during the third and fourth waves, respectively. Phylogeographic reconstruction points toward distinct differences in viral importation and exportation patterns associated with the Alpha, Beta, Delta, and Omicron variants and subvariants, when considering both Africa versus the rest of the world and viral dissemination within the continent. Our epidemiological and phylogenetic inferences therefore underscore the heterogeneous nature of the pandemic on the continent and highlight key insights and challenges, for instance, recognizing the limitations of low testing proportions. We also highlight the early warning capacity that genomic surveillance in Africa has had for the rest of the world with the detection of new lineages and variants, the most recent being the characterization of various Omicron subvariants. CONCLUSION Sustained investment for diagnostics and genomic surveillance in Africa is needed as the virus continues to evolve. This is important not only to help combat SARS-CoV-2 on the continent but also because it can be used as a platform to help address the many emerging and reemerging infectious disease threats in Africa. In particular, capacity building for local sequencing within countries or within the continent should be prioritized because this is generally associated with shorter turnaround times, providing the most benefit to local public health authorities tasked with pandemic response and mitigation and allowing for the fastest reaction to localized outbreaks. These investments are crucial for pandemic preparedness and response and will serve the health of the continent well into the 21st century

AN ASSESSMENT OF THE INFLUENCE OF MATHEMATICS TEACHERS’ TRAINING ON USE OF QUESTIONING TECHNIQUE AND STUDENTS’ ACHIEVEMENT IN MATHEMATICS IN PUBLIC SECONDARY SCHOOLS IN MWALA SUB-COUNTY, MACHAKOS COUNTY, KENYA

Purpose: Mathematics’ teachers play an important role in teaching of concepts in mathematics and ensuring that students register good grades in tests. However, in Mwala Sub-county, the scenario is different with many students registering low achievement in mathematics. Thus, the purpose of this study was to assess the influence of mathematics’ teachers training on use of questioning technique on students’ achievement in mathematics in public secondary schools in Mwala Sub-county, Machakos County, Kenya.Methodology: The study was guided by the learning theory. This study adopted mixed methodology and thus applied concurrent triangulation research design. Questionnaires were used to gather quantitative data from mathematics’ teachers whereas interview guides were used to collect qualitative data from principals. Qualitative data were analyzed thematically based on study objectives and presented in narrative form. Quantitative data were analyzed using descriptive statistics and inferentially using linear regression analysis in Statistical Package for Social Sciences (SPSS Version 23) and presented using tables.Findings: The study established that many mathematics’ teachers have basic training on how to use the questioning technique in teaching mathematics. However, this has not improved students’ achievement in mathematics.Contribution to theory, policy and practice: The study recommends that mathematics’ teachers should undergo many in-service trainings on how improve the questioning technique skills. Mathematics’ teachers interact more with experienced colleagues by attending seminars and workshops designed to improve their experience and levels of exposure to different approaches of questioning. The Ministry of Education should create room for more in-service trainings for the newly recruited mathematics’ teachers.</jats:p

Mediation by Organizational Design in the Influence of Organizational Ambidexterity on the Performance of Large Manufacturing Firms in Kenya

The aim of this study was to establish the role of organizational design in the organizational ambidexterity - performance relationship among large manufacturing firms (LMFs) in Kenya. The studies linking ambidexterity to organizational performance are few and with mixed findings. The few studies indicate that there is no clear ambidexterity - organizational performance relationship. The research was founded on dynamic capabilities and configurations theories. Based on the reviewed literature, a conceptual model and hypotheses were formulated. The study was guided by positivist philosophy. The population of the research was the entire 107 Kenyan large manufacturing firms (LMFs). Cross-sectional research design was used. Primary data in respect of predictor variables was used and was collected using a structured questionnaire. The respondents were the senior managers of the large manufacturing firms (LMFs) in Kenya; namely Chief Executive Officers/Managing Directors (CEOs/MDs) or General Managers (GMs), or Heads of departments (HODs). Descriptive statistics, correlations, linear, multiple and hierarchical regressions were applied in the data scrutiny and interpretation. The study results showed partial organizational design mediating role in the organizational ambidexterity - performance association of LMFs in Kenya. The study findings are useful to practitioners and managers of LMFs, policymakers in government as well as scholars and researchers. The study recommends further studies on the mediating role of organizational design, different variable operationalization, diversify respondents and context as well as longitudinal study.</jats:p