Iridium-palladium binary alloy as a counter electrode in dye-sensitized solar cells

This study is concerned with the iridium-palladium (Ir-Pd) binary alloy as a counter electrode (CE) for DSSC. The CE was prepared using the liquid phase deposition (LPD) technique. The influence of the concentration of hydrogen hexachloroiridate(IV) hydrate (H2Cl6Ir·H2O) on the properties and the performance of the device was investigated. The source of iridium was H2Cl6Ir·H2O. XRD analysis confirmed that the dominant phase of Ir-Pd existed in the sample. The grain size of Ir-Pd increased with the increase in the concentration of H2Cl6Ir·H2O until an optimum concentration of 0.7 mM was reached. The % wt of Ir was found to increase with the concentration of H2Cl6Ir·H2O. The device utilizing Ir-Pd CE with 0.7 mM H2Cl6Ir·H2O demonstrated the highest power conversion efficiency (PCE) of 5.84%, beating that of the device with Pt CE having a PCE of 5.04%. This is because the device possesses the lowest charge transfer resistance (Rct), highest recombination resistance (Rcr), and longest carrier lifetime (τ), and the device possesses the highest reduction current (Jpc) and incident-photon conversion efficiency (IPCE). The PCE was significantly affected by Ir content in the binary alloy of Ir-Pd. According to the PCE result, Ir-Pd CE was found as a suitable substitution for Pt as CE for the device.

Predictors of pediatric HIV disclosure among caregivers of HIV positive children attending special treatment clinic in dalhatu araf specialist hospital, Lafia, Nigeria

Background

HIV-infected children now live longer due to the availability of HIV counseling, testing, and treatment with highly active antiretroviral treatment (HAART). Efforts to help these children to know about the HIV infection and their status are important steps toward long-term disease management. This study was conducted to determine the factors associated with pediatric HIV disclosure among caregivers of children attending Special Treatment Clinic at Dalhatu Araf Specialist Hospital, Lafia.

Methods

This was a descriptive cross-sectional study conducted among 160 caregivers of children attending the Special Treatment Clinic (STC) at DASH, Lafia, selected by systematic random sampling technique. Interviewer administered structured questionnaire was used to collect data, while bivariate and multivariate analyses were done with the Epi Info version 7.

Results

Pediatric HIV disclosure rate in this study was 33.8%. The mean age at pediatric HIV disclosure was 9.85 ± 1.86 years. The independent predictors for pediatric HIV disclosure following logistic regression were child's age, 10-14 years (AOR = 4.46; 95%CI 1.47-13.61), child knowledge of caregivers' HIV status (AOR = 51.18; 95%CI 13.40-195.66), and caregivers' age ≥40 years (AOR = 3.58; 95%CI 1.25-11.74).

Conclusions

The pediatric HIV disclosure was low in this study due to the caregivers' and their wards' factors. Health care workers need to intensify health education on the benefit of pediatric HIV disclosure at the STC clinic.

Determination of methylprednisolone acetate in biological fluids at gold nanoparticles modified ITO electrode

The electrochemical behavior of a corticosteroid methylprednisolone (MP), used for doping, has been studied at gold nanoparticles modified indium tin oxide (nanoAu/ITO) electrode. The nanoAu/ITO electrode exhibited an effective catalytic response towards its oxidation and lowered its oxidation potential by approximately 127 mV when compared with bare ITO electrode. Oxidation of MP has been carried out in phosphate containing electrolyte in the pH range 2.13-10.00 and a well-defined oxidation peak was noticed. Linear concentration curves are obtained over the concentration range 0.01-1.0 microM with a detection limit of 2.68 x 10(-7)M at nanoAu/ITO electrode. A diffusion coefficient of 2.36 x 10(-6)cm(2)/s is calculated for MP using chronoamperometry. The proposed method is effectively applied to detect the concentration of MP in pharmaceutical formulations and human blood plasma and urine samples. A comparison of MP concentration determined in blood plasma and urine by the proposed method and GC/MS indicated that the results are essentially similar. It is believed that the method will be useful in determining this drug in case of doping.