Modification of alumina matrices through chemical etching and electroless deposition of nano-Au array for amperometric sensing

Simple nanoporous alumina matrix modification procedure, in which the electrically highly insulating alumina barrier layer at the bottom of the pores is replaced with the conductive layer of the gold beds, was described. This modification makes possible the direct electron exchange between the underlying aluminum support and the redox species encapsulated in the alumina pores, thus, providing the generic platform for the nanoporous alumina sensors (biosensors) with the direct amperometric signal readout fabrication

Voltammetric investigation of the kinetics of alkali metal cation reduction in N,N-dimethylformamide

The standard electron-transfer heterogeneous rate constant of lithium, potassium, sodium and caesium amalgams in N,N-dimethylformamide was ascertained employing cyclic voltammetry in an effort to relate the presence of a non-equilibrium electrode reaction at the dropping lithium amalgam electrode to the variation of the lithium amalgam electrode potential with amalgam electrode con- figuration, i.e. whether streaming, dropping or stationary. Such variations are not observed at other alkali metal amalgam electrodes. In the dipolar aprotic solvents the standard electron-transfer heterogeneous rate constant for the Li(Hg) electrode increases as the solvating power for Li+ decreases, i.e. dimethyl sulphoxide < di- methylformamide < propylene carbonate. Water is a much stronger solvator of Li+ than is propylene carbonate, but the electron transfer is faster in water than in propylene carbonate; the important role of entropic contributions in ion solvation is discussed as an explanation

The electrochemical behaviour of galena (lead sulphide) — II. Cathodic reduction

The cathodic reduction of natural samples of high-purity galena has been studied in both acidic and alkaline solutions. The products of the reaction are lead metal and, depending on the pH value, the various forms of sulphide ion. Linear-sweep voltammetric measurements in solutions of various pH values have been used to obtain current-potential data from which possible mechanisms for the reaction have been derived. Results are also presented that show that the cathodic reduction of anodically produced sulphur is possible, but that the rate of reduction is strongly dependent upon the amount of sulphur present and its history

Planning schistosomiasis control: investigation of alternative sampling strategies for Schistosoma mansoni to target mass drug administration of praziquantel in East Africa.

In schistosomiasis control, there is a need to geographically target treatment to populations at high risk of morbidity. This paper evaluates alternative sampling strategies for surveys of Schistosoma mansoni to target mass drug administration in Kenya and Ethiopia. Two main designs are considered: lot quality assurance sampling (LQAS) of children from all schools; and a geostatistical design that samples a subset of schools and uses semi-variogram analysis and spatial interpolation to predict prevalence in the remaining unsurveyed schools. Computerized simulations are used to investigate the performance of sampling strategies in correctly classifying schools according to treatment needs and their cost-effectiveness in identifying high prevalence schools. LQAS performs better than geostatistical sampling in correctly classifying schools, but at a cost with a higher cost per high prevalence school correctly classified. It is suggested that the optimal surveying strategy for S. mansoni needs to take into account the goals of the control programme and the financial and drug resources available