An exfoliated graphite-based Bisphenol A electrochemical sensor

The use of an exfoliated graphite (EG) electrode in the square wave voltammetric detection of bisphenol A (a model phenolic pollutant) in water, whereby the phenolic electrode fouling challenge is mitigated, is described. The oxidation peak of BPA was observed at about 0.45 V in phosphate buffer solution at pH 10. The current response exhibited a linear relationship with the concentration over a range from 1.56 μM–50 μM. The detection limit was calculated to be 0.76 μM. The EG electrode surface was renewed after each measurement with excellent reproducibility. A real sample application was also investigated

Socio-economic aspects in draught animal-crop linkages: a diagnostic study of Tsholotsho, Chinyika and Mutoko smallholder farming areas of Zimbabwe

A research paper on Zimbabwe's small-holder farmers' constraints in crop production due to shortages of draught animal power during the 1994/95 agricultural season.A survey was conducted on 451 households in Tsholotsho, Chinyika and Mutoko smallholder areas to understand farmers’ crop production constraints in relation to draught animal power (DAP) during the 1994/95 agricultural season. Farmers without DAP constituted 48.6 percent in the three districts. Of these, 54.5 percent had access to neighbours’ or relatives’ animals. The rest hired or worked in others’ fields in exchange for draught animals. Animal diseases and shortage of grazing land were noted as the major constraints in animal production. Both farmer education and experience as well as household head were found to be associated with district (p<0.001). Tsholotsho had the largest number of farmers (52.8 percent) with more than 10 years experience while Mutoko had the largest proportion (43.3 percent) of Master farmers. Farmer education and experience were found to be independent of sex. The average land holdings per farmer for Tsholotsho, Chinyika and Mutoko were 6.21 ha, 4.22 ha and 1.62 ha, respectively. Tsholotsho is a dryland communal area whilst Chinyika is a relatively wet area. Mutoko is a typical communal area with a high population pressure. Maize is the main crop in Chinyika and Mutoko whilst millet is the most common in Tsholotsho

Physiological parameters of seed vigour in ex situ stored sorghum germplasm

Viability and vigour are seed quality parameters that affect the seed chain. Seed vigour is a measure of accumulated damage in seed as viability declines from physiological maturity. This study aimed at determining the seed vigour of various sorghum genotypes stored ex situ for 10 years using the Heat Shock Stress Test (HSST), Cold Test (CT), Standard Germination Test (SGT) and field germination. The samples from the regeneration trial were kept in ex situ storage at 0-4°C and 40% relative humidity from 2003 to 2014. The experiments were arranged in a completely randomised design with four replication and differences in radicle length, shoot length for the 65 genotypes evaluated at 5% level of significance. An unpaired T- test was used to compare the accuracy of the quality methods in predicting field emergence. All the evaluated genotypes responded differentially to all the vigour test methods. There were significant differences (P<0.01) in the performance of genotypes with respect to radical and shoot length in response to the CT, HSST and the SGT. The results of CT and HSST predicted field emergence better than the standard germination test. None of the quality test methods and a strong and significant correlation with field emergence. Genotypes IS 30260 and IS 34637 were vigourous as they had the highest shoot length of 43.75 and 42.38 mm and IS 30063 had 45.52 mm in root length after 48 h of incubation. Overall, this study showed that field emergence of sorghum cannot be accurately predicted from a standard germination, HSST and CT

Subtle Longitudinal Alterations in Env Sequence Potentiate Differences in Sensitivity to Broadly Neutralizing Antibodies following Acute HIV-1 Subtype C Infection

Broadly neutralizing antibodies (bNAbs) for HIV-1 prevention or cure strategies must inhibit transmitted/founder and reservoir viruses. Establishing sensitivity of circulating viruses to bNAbs and genetic patterns affecting neutralization variability may guide rational bNAbs selection for clinical development. We analyzed 326 single env genomes from nine individuals followed longitudinally following acute HIV-1 infection, with samples collected at ~1 week after the first detection of plasma viremia; 300 to 1,709 days postinfection but prior to initiating antiretroviral therapy (ART) (median = 724 days); and ~1 year post ART initiation. Sequences were assessed for phylogenetic relatedness, potential N- and O-linked glycosylation, and variable loop lengths (V1 to V5). A total of 43 env amplicons (median = 3 per patient per time point) were cloned into an expression vector and the TZM-bl assay was used to assess the neutralization profiles of 15 bNAbs targeting the CD4 binding site, V1/V2 region, V3 supersite, MPER, gp120/gp41 interface, and fusion peptide. At 1 μg/mL, the neutralization breadths were as follows: VRC07-LS and N6.LS (100%), VRC01 (86%), PGT151 (81%), 10-1074 and PGT121 (80%), and less than 70% for 10E8, 3BNC117, CAP256.VRC26, 4E10, PGDM1400, and N123-VRC34.01. Features associated with low sensitivity to V1/V2 and V3 bNAbs were higher potential glycosylation sites and/or relatively longer V1 and V4 domains, including known "signature" mutations. The study shows significant variability in the breadth and potency of bNAbs against circulating HIV-1 subtype C envelopes. VRC07-LS, N6.LS, VRC01, PGT151, 10-1074, and PGT121 display broad activity against subtype C variants, and major determinants of sensitivity to most bNAbs were within the V1/V4 domains. IMPORTANCE Broadly neutralizing antibodies (bNAbs) have potential clinical utility in HIV-1 prevention and cure strategies. However, bNAbs target diverse epitopes on the HIV-1 envelope and the virus may evolve to evade immune responses. It is therefore important to identify antibodies with broad activity in high prevalence settings, as well as the genetic patterns that may lead to neutralization escape. We investigated 15 bNAbs with diverse biophysical properties that target six epitopes of the HIV-1 Env glycoprotein for their ability to inhibit viruses that initiated infection, viruses circulating in plasma at chronic infection before antiretroviral treatment (ART), or viruses that were archived in the reservoir during ART in subtype C infected individuals in South Africa, a high burden country. We identify the antibodies most likely to be effective for clinical use in this setting and describe mutational patterns associated with neutralization escape from these antibodies

infection in wildfowl: a continental-scale study across Africa Understanding the ecological drivers of avian influenza virus

Despite considerable effort for surveillance of wild birds for avian influenza viruses (AIVs), empirical investigations of ecological drivers of AIV prevalence in wild birds are still scarce. Here we used a continental-scale dataset, collected in tropical wetlands of 15 African countries, to test the relative roles of a range of ecological factors on patterns of AIV prevalence in wildfowl. Seasonal and geographical variations in prevalence were positively related to the local density of the wildfowl community and to the wintering period of Eurasian migratory birds in Africa. The predominant influence of wildfowl density with no influence of climatic conditions suggests, in contrast to temperate regions, a predominant role for inter-individual transmission rather than transmission via long-lived virus persisting in the environment. Higher prevalences were found in Anas species than in non-Anas species even when we account for differences in their foraging behaviour (primarily dabbling or not) or their geographical origin (Eurasian or Afro-tropical), suggesting the existence of intrinsic differences between wildfowl taxonomic groups in receptivity to infection. Birds were found infected as often in oropharyngeal as in cloacal samples, but rarely for both types of sample concurrently, indicating that both respiratory and digestive tracts may be important for AIV replication. Keywords: influenza A virus; pathogen transmission; disease ecology; wild birds; tropical; migratio

A Decolonial Critique of the Racialized “Localwashing” of Extraction in Central Africa

Responding to calls for increased attention to actions and reactions “from above” within the extractive industry, we offer a decolonial critique of the ways in which corporate entities and multinational institutions propagate racialized rhetoric of “local” suffering, “local” consultation, and “local” fault for failure in extractive zones. Such rhetoric functions to legitimize extractive intervention within a set of practices that we call localwashing. Drawing from a decade of research on and along the Chad-Cameroon Oil Pipeline, we show how multi-scalar actors converged to assert knowledge of, responsibility for, and collaborations with “local” people within a racialized politics of scale. These corporate representations of the racialized “local” are coded through long-standing colonial tropes. We identify three interrelated and overlapping flexian elite rhetoric(s) and practices of racialized localwashing: (a) anguishing, (b) arrogating, and (c) admonishing. These elite representations of a racialized “local” reveal diversionary efforts “from above” to manage public opinion, displace blame for project failures, and domesticate dissent in a context of persistent scrutiny and criticism from international and regional advocates and activists

Electrolytic deposition of manganese dioxide from Nigerian manganese ore using graphite electrodes

Abstract: Super rich manganese dioxide got deposited at the anode when manganese sulphate solution was electrolytically decomposed, and the deposits called Electrolytic Manganese Dioxide (EMD). Manganese ore containing about 35.79% manganese from Ka’oje (Kebbi State, Nigeria) with pyrolusite (MnO2) as the major manganese mineral alongside iron mineral present as hematite, was the resource material. Some 1973.31g of beneficiated ore sample (75 to 600μm) was isothermally reduced with charcoal (52.17% carbon) at 6000C for one hour. The paramagnetic high oxide ore got reduced to a ferromagnetic lower oxide containing 38.90% manganese. Some 610g portions of the reduced ore were leached in varied concentrations of sulphuric acid (1.0M, 1.5M and 2.0M) at 500C for one hour and 42.36% leaching efficiency was achieved with 2.0M acid. Calculated elemental mass balance revealed that 2.0M acid dissolved 100.52g of manganese into the leach liquor as manganese sulphate along with 13.83g of iron and 7.47g of aluminium as the major elements. Each leach filtrate was purified with aqueous sodium hydroxide except some 600ml of filtrate from 2.0M acid leaching which was decomposed unpurified for comparison. The filtrates were respectively electrolyzed at 2.5V, 3.0V and 4.0V driving potentials for five hours using graphite electrodes. Analyses showed that the purified liquor extracted with 2.0M acid and electrolysed at 4.0V deposited the best quantity and quality of EMD, containing 98% MnO2. This high grade EMD is a principal precursor in Ferro-alloy production for steel making and also an important raw material for electrochemical cells and other allied manganese-based chemicals

Interplay between edge states and simple bulk defects in graphene nanoribbons

We study the interplay between the edge states and a single impurity in a zigzag graphene nanoribbon. We use tight-binding exact diagonalization techniques, as well as density functional theory calculations to obtain the eigenvalue spectrum, the eigenfunctions, as well the dependence of the local density of states (LDOS) on energy and position. We note that roughly half of the unperturbed eigenstates in the spectrum of the finite-size ribbon hybridize with the impurity state, and the corresponding eigenvalues are shifted with respect to their unperturbed values. The maximum shift and hybridization occur for a state whose energy is inverse proportional to the impurity potential; this energy is that of the impurity peak in the DOS spectrum. We find that the interference between the impurity and the edge gives rise to peculiar modifications of the LDOS of the nanoribbon, in particular to oscillations of the edge LDOS. These effects depend on the size of the system, and decay with the distance between the edge and the impurity.Comment: 10 pages, 15 figures, revtex

Political activism across the life course

The study of political activism has neglected people’s personal and social relationships to time. Age, life course and generation have become increasing important experiences for understanding political participation and political outcomes (e.g. Brexit), and current policies of austerity across the world are affecting people of all ages. At a time when social science is struggling to understand the rapid and unexpected changes to the current political landscape, the essay argues that the study of political activism can be enriched by engaging with the temporal dimensions of people’s everyday social experiences because it enables the discovery of political activism in mundane activities as well as in banal spaces. The authors suggest that a values-based approach that focuses on people’s relationships of concern would be a suitable way to surface contemporary political sites and experiences of activism across the life course and for different generations

Casting a Wide Net: HIV Drug Resistance Monitoring in Pre-Exposure Prophylaxis Seroconverters in the Global Evaluation of Microbicide Sensitivity Project

Background: Evidence of HIV drug resistance (HIVDR) in individuals using oral pre-exposure prophylaxis (PrEP) who acquire HIV is limited to clinical trials and case studies. More data are needed to understand the risk of HIVDR with oral PrEP during PrEP rollout. Mechanisms to collect these data vary, and are dependent on cost, scale of PrEP distribution, and in-country infrastructure for the identification, collection, and testing of samples from PrEP seroconverters. / Methods: The Global Evaluation of Microbicide Sensitivity (GEMS) project, in collaboration with country stakeholders, initiated HIVDR monitoring among new HIV seroconverters with prior PrEP use in Eswatini, Kenya, South Africa, and Zimbabwe. Standalone protocols were developed to assess HIVDR among a national sample of PrEP users. In addition, HIVDR testing was incorporated into existing demonstration projects for key populations. / Lessons learned: Countries are supportive of conducting a timelimited evaluation of HIVDR during the early stages of PrEP rollout. As PrEP rollout expands, the need for long-term HIVDR monitoring with PrEP will need to be balanced with maintaining national HIV drug resistance surveillance for pretreatment and acquired drug resistance. Laboratory capacity is a common obstacle to setting up a monitoring system. / Conclusions: Establishing HIV resistance monitoring within PrEP programs is feasible. Approaches to drug resistance monitoring may evolve as the PrEP programs mature and expand. The methods and implementation support offered by GEMS assisted countries in developing methods to monitor for drug resistance that best fit their PrEP program needs and resources