Mercury exposure in a low-income community in South Africa

Objectives. To establish whether a specific community in a gold mining area, with potentially associated small-scale gold mining activities, was exposed to mercury.Methods. The community was situated in Mpumalanga, where some potential sources of mercury emissions may have an impact. Adults ≥18 years were considered eligible. Biological monitoring, supported by questionnaires, was applied. Thirty respondents completed the questionnaire which covered demographics, energy use, food and waterconsumption, neurological symptoms, and confounders such as alcohol consumption and brain injuries. Mercury levels were determined in 28 urine and 20 blood samples of these respondents.Results. Three (15%) of the blood samples exceeded the guideline

Graphene-Polyaniline Biosensor for Carbamate Pesticide Determination in Fruit Samples

In this study, a simple, sensitive, and low cost electrochemical biosensor for the quantitative determination of carbamate pesticides has been constructed. A composite consisting of polyaniline (PANI) and graphene oxide was electrochemically synthesised on a platinum electrode. This sensor platform was then used in the biosensor construction by electrostatic attachment of the enzyme, horseradish peroxidase (HRP) onto the surface of the Pt/GO-PANI electrode. Voltammetric results concluded that HRP immobilised on the Pt/GO-PANI composite retained its bio-electrocatalytic activity towards the reduction of H2O2 and was not changed during its immobilisation. The Pt/GO-PANI/HRP biosensor was then applied to successfully detect standard carbamate pesticides in a 0.1 M phosphate buffer (PB; pH = 6.8) solution. Various performance and stability parameters were evaluated for the Pt/GO-PANI/HRP biosensor, which included the optimal enzyme loading, effect of pH and long-term stability of the biosensor on its amperometric behaviour. The Pt/GO-PANI/HRP biosensor was finally applied to the detection of three carbamate pesticides of carbaryl, carbofuran, and methomyl using the enzyme inhibition method. Carbaryl, carbofuran, and methomyl analyses were amperometrically determined using spiked real samples of orange, pear, and grapes, within a concentration range of 0.01–0.3 mg/L. These results indicated that the biosensor is sensitive enough to detect carbamate pesticides in real fruit matrices. The detection limit for carbaryl, carbofuran, and methomyl in real fruit samples by amperometric method was determined to be 0.136 mg/L, 0.145 mg/L, and 0.203 mg/L, respectively. The application of the Pt/GO-PANI/HRP biosensor has demonstrated that the biosensor is sensitive enough for amperometric detection and could be a useful tool in the screening of these pesticides at low concentrations

Mercury exposure in a low-income community in South Africa

Objectives. To establish whether a specific community in a gold mining area, with potentially associated small-scale gold mining activities, was exposed to mercury. Methods. The community was situated in Mpumalanga, where some potential sources of mercury emissions may have an impact. Adults ≥18 years were considered eligible. Biological monitoring, supported by questionnaires, was applied. Thirty respondents completed the questionnaire which covered demographics, energy use, food and water consumption, neurological symptoms, and confounders such as alcohol consumption and brain injuries. Mercury levels were determined in 28 urine and 20 blood samples of these respondents. Results. Three (15%) of the blood samples exceeded the guideline

Spectroelectrochemical reactivities of novel polyaniline nanotube pesticide biosensors

Summary: The preparation and characterisation of electrosynthetic polyaniline nanomaterials doped with phenanthrene sulphonic acid (PSA) is being presented. The polymeric nanomaterials prepared include processable poly(o-methoxy aniline) (POMA) and poly(2,5-dimethoxy aniline) (PDMA). Spectroelectrochemical reactivities of the electroactive polymeric nanotube systems as well as the nanobiosensor systems were studied by SEM, FTIR, UV-Vis and Subtractively Normalised Fourier Transformed Infrared Spectroscopy (SNIFTIRS) techniques. Furthermore, cyclic and differential pulse voltammetric studies of the nanomaterials were also performed using platinum or thiol-modulated gold electrodes. The SEM studies confirmed the nanorod morphology of the polyanilines. The heterogeneous rate constant, k o , for the nanopolymeric material and the diffusion coefficient of electrons, D e , was calculated and found to be in agreement with values expected for electron hopping along conducting polymer chains. Organophosphate pesticide nanobiosensor devices were prepared by encapsulating acetylcholinesterase (AChE) in the nanopolymeric composite. The biosensor amperometric response to the organophosphate pesticide called diazinon and the carbamate pesticide called carbofuran were studied. The sensor responses to pesticides followed typical electrochemical Michaelis-Menten kinetics

Witchcraft and the Somerset idyll : The depiction of folk belief in Walter Raymond’s novels

The work of Walter Raymond (1852-1931) is now largely forgotten. Yet his Somerset novels, complemented by his ethnographic writings, contain depictions of local witchcraft belief that are worthy of study in literary and historical contexts. They raise issues regarding the fictional depiction of rural life and tradition, and the value of fiction as a folkloric and historical sourcePeer reviewe