Robust Arduino controlled spin coater using a novel and simple gravity chuck design.

Spin coaters offer an invaluable method of thin film fabrication. Various implementations, both proprietary and open-source exist, offering vacuum and gravity samples chucks. These implementations vary in their reliability, ease-of-use, cost, and versatility. Here we present a novel easy-to-use open-source gravity-chuck type spin coater with minimal points of failure at a material cost of around 100 USD (1500 ZAR). The unique chuck design makes use of interchangeable brass plate sample masks, each specific to a sample size, these can be made with basic skills and common hand tools. In comparison, replacement chucks for commercial alternatives can cost as much as the entire spin coater we present. Open-source hardware such as this provides an example for individuals in the field on the design and development of hardware where reliability, cost, and flexibility are most important, as is the case for many institutions in developing countries.

Adaptation of a social vulnerability index for measuring social frailty among East African women.

BACKGROUND: The number of older women living with HIV in Africa is growing, and their health outcomes may be adversely impacted by social frailty, which reflects deficits in social resources that accumulate over the lifespan. Our objective was to adapt a Social Vulnerability Index (SVI) originally developed in Canada for use in a study of older women living with or without HIV infection in Mombasa, Kenya. METHODS: We adapted the SVI using a five-step process: formative qualitative work, translation into Kiswahili, a Delphi procedure, exploration of potential SVI items in qualitative work, and a rating and ranking exercise. Four focus group discussions (FGD) were conducted (three with women living with HIV and one with HIV-negative women), and two expert panels were constituted for this process. RESULTS: Themes that emerged in the qualitative work were physical impairment with aging, decreased family support, a turn to religion and social groups, lack of a financial safety net, mixed support from healthcare providers, and stigma as an added burden for women living with HIV. Based on the formative FGD, the expert panel expanded the original 19-item SVI to include 34 items. The exploratory FGD and rating and ranking exercise led to a final 16-item Kenyan version of the SVI (SVI-Kenya) with six domains: physical safety, support from family, group participation, instrumental support, emotional support, and financial security. CONCLUSIONS: The SVI-Kenya is a holistic index to measure social frailty among older women in Kenya, incorporating questions in multiple domains. Further research is needed to validate this adapted instrument.

Annealing effect on the structural and optical behavior of ZnO:Eu3+ thin film grown using RF magnetron sputtering technique and application to dye sensitized solar cells.

Eu-doped ZnO (ZnO:Eu3+) thin films deposited by RF magnetron sputtering have been investigated to establish the effect of annealing on the red photoluminescence. PL spectra analysis reveal a correlation between the characteristics of the red photoluminescence and the annealing temperature, suggesting efficient energy transfer from the ZnO host to the Eu3+ ions as enhanced by the intrinsic defects levels. Five peaks corresponding to 5D0-7FJ transitions were observed and attributed to Eu3+ occupancy in the lattice sites of ZnO thin films. As a proof of concept a dye sensitized solar cell with ZnO:Eu3+ thin films of high optical transparency was fabricated and tested yielding a PCE of 1.33% compared to 1.19% obtained from dye sensitized solar cells (DSSC) with pristine ZnO without Eu produced indicating 11.1% efficiency enhancement which could be attributed to spectral conversion by the ZnO:Eu3+.

Probing the stoichiometry dependent catalytic activity of nickel selenide counter electrodes in the redox reaction of iodide/triiodide electrolyte in dye sensitized solar cells.

Nickel selenide (Ni x Se y ) systems have received much attention in recent years as potential low cost counter electrodes (CEs) in dye sensitized solar cells (DSSCs). Their electrocatalytic activities are comparable to that of the conventional platinum CE. Despite their achievements, the effect of stoichiometry on their catalytic performance as CEs in DSSCs still remains unclear, hence the motivation for this work. Different stoichiometries of Ni x Se y were synthesized via a colloidal method in oleylamine or oleylamine/oleic acid mixture at the appropriate synthetic temperature and Ni to Se precursor ratio. X-ray diffraction revealed that different stoichiometries of nickel selenide were formed namely, NiSe2, Ni3Se4, Ni0.85Se, NiSe and Ni3Se2. Scanning electron microscopy showed that all the stoichiometries had predominantly spherical-like morphologies. Cyclic voltammetry, electrochemical impedance spectroscopy analysis and the photovoltaic performances of the DSSCs fabricated using the different Ni x Se y CEs revealed that selenium rich stoichiometries performed better than the nickel rich ones. Consequently, the catalytic activity towards the redox reaction of the triiodide/iodide electrolyte and hence the power conversion efficiency (PCE) followed the order of NiSe2 > Ni3Se4 > Ni0.85Se > NiSe > Ni3Se2 with PCE values of 3.31%, 3.25%, 3.17%, 2.35% and 1.52% respectively under ambient conditions.

Effect of thermal treatment on ZnO:Tb3+ nano-crystalline thin films and application for spectral conversion in inverted organic solar cells.

Down conversion has been applied to minimize thermalization losses in photovoltaic devices. In this study, terbium-doped ZnO (ZnO:Tb3+) thin films were deposited on ITO-coated glass, quartz and silicon substrates using the RF magnetron sputtering technique fitted with a high-purity (99.99%) Tb3+-doped ZnO target (97% ZnO, 3% Tb) for use in organic solar cells as a bi-functional layer. A systematic study of the film crystallization dynamics was carried out through elevated temperature annealing in Ar ambient. The films were characterized using grazing incidence (XRD), Rutherford backscattering spectrometry (RBS), atomic force microscopy, and UV-visible transmittance and photoluminescence measurements at an excitation wavelength of 244 nm. The tunability of size and bandgap of ZnO:Tb3+ nanocrystals with annealing exhibited quantum confinement effects, which enabled the control of emission characteristics in ZnO:Tb3+. Energy transfer of ZnO → Tb3+ (5D3-7F5) was also observed from the photoluminescence (PL) spectra. At an inter-band resonance excitation of around 300-400 nm, a typical emission band from Tb3+ was obtained. The ZnO:Tb3+ materials grown on ITO-coated glass were then used as bi-functional layers in an organic solar cell based on P3HT:PCBM blend, serving as active layers in an inverted device structure. Energy transfer through down conversion between ZnO and Tb3+ led to enhanced absorption in P3HT:PCBM in the 300-400 nm range and subsequently augmented J sc of a Tb3+-based device by 17%.

Short communication: High prevalence of transmitted antiretroviral drug resistance among newly HIV type 1 diagnosed adults in Mombasa, Kenya.

Abstract In view of the recent antiretroviral therapy (ART) scale-up in Kenya, surveillance of transmitted HIV drug resistance (TDR) is important. A cross-sectional survey was conducted among newly HIV-1 diagnosed, antiretroviral-naive adults in Mombasa, Kenya. Surveillance drug resistance mutations (SDRMs) were identified according to the 2009 WHO list. HIV-1 subtypes were determined using REGA and SCUEAL subtyping tools. Genotypic test results were obtained for 68 of 81 participants, and SDRMs were identified in 9 samples. Resistance to nonnucleoside reverse transcriptase inhibitors (K103N) occurred in five participants, yielding a TDR prevalence of 7.4% (95% confidence interval 2.4-16.3%). Frequencies of HIV-1 subtypes were A (70.6%), C (5.9%), D (2.9%), and unique recombinant forms (20.6%). The TDR prevalence found in this survey is higher than previously reported in different regions in Kenya. These findings justify increased vigilance with respect to TDR surveillance in African regions where ART programs are scaled-up in order to inform treatment guidelines.