Chemistryhttp://hdl.handle.net/10566/3862024-03-19T05:56:26Z2024-03-19T05:56:26ZCopper-modified carbon nano-onions as electrode modifiers for the electroanalysis of the antiretroviral drug efavirenzMokwebo, K VIwuoha, E IMurphy, EGuin, S Khttp://hdl.handle.net/10566/92922024-02-14T00:00:45Z2023-01-01T00:00:00ZCopper-modified carbon nano-onions as electrode modifiers for the electroanalysis of the antiretroviral drug efavirenz
Mokwebo, K V; Iwuoha, E I; Murphy, E; Guin, S K
The high prescription and consumption rate of antiretroviral drugs (ARV) such as Efavirenz (EFV) in South Africa for the treatment of the human immunodeficiency virus (HIV) has resulted in its presence in wastewater and surface water. Herein we report the electroanalysis of EFV at oxidised boron-nitrogen doped carbon nano-onions (oxi-BNCNO) and microscale branched copper cluster (CuC) modified glassy carbon electrodes. Potentiostatic electrodeposition of CuC on the oxi-BNCNO/GCE platform resulted in a stable and electrocatalytic surface that accelerated electron transfer between the analyte and the CuC/oxi-BNCNO/GCE surface, making quantification efficient. The electroactive surface area of CuC/oxi-BNCNO/GCE was estimated as being 3 times higher than bare GCE and twice that of oxi-BNCNO/GCE. The electrooxidation of EFV on a CuC/oxi-BNCNO/GCE sensor resulted in a pH-dependant anodic peak in the potential range of 0.8 to 1.2 V vs Ag/AgCl (3M KCl).
2023-01-01T00:00:00ZMulti-objective optimization of a metal hydride reactor coupled with phase change materials for fast hydrogen sorption timeNyamsi, Serge NyallangPasupathi, SivakumarTolj, Ivanhttp://hdl.handle.net/10566/92862024-02-14T00:00:43Z2023-01-01T00:00:00ZMulti-objective optimization of a metal hydride reactor coupled with phase change materials for fast hydrogen sorption time
Nyamsi, Serge Nyallang; Pasupathi, Sivakumar; Tolj, Ivan
Recently, the utilization of phase change materials (PCM) for the heat storage/recovery of the metal hydride's reaction heat has received increasing attention. However, the poor heat management process makes hydrogen sorption very slow during heat recycling. In this work, the H2 charging/discharging performance of a metal hydride tank (MHT) filled with LaNi5 and equipped with a paraffin-based (RT35) PCM finned jacket as a passive heat management medium is numerically investigated. Using a two-dimensional mathematical model validated with our in-house experiments, the effects of design parameters such as PCM thermophysical properties and the fin size on hydrogen charging/discharging times of the MHT are investigated systematically. The results showed that the PCM's melting point and apparent heat capacity have a conflicting impact on the hydrogen sorption times, i.e., the low melting point and high specific heat capacity reduce the H2 charging time. In contrast, the hydrogen discharging time follows the opposite trend. As a result, a multi-objective optimization was conducted to simultaneously minimize the H2 charging/discharging times using the thermal properties and size of the PCM. The optimum solutions selected from the Pareto front show that the PCM melting point should be around 42–43 ◦C for fixed hydrogen ab/desorption pressures of 10/1.5 bar.
2023-01-01T00:00:00ZThe crystal structure of fac-tricarbonyl((pyridin-2-yl)methanamino-κ2N,N′)-((pyridin-2-yl)methanamino-κN)rhenium(I) nitrate,C15H16O3N4ReAlexander, Orbett TRamoba, Lesetja VMalan, Frederick Phttp://hdl.handle.net/10566/92852024-02-15T07:54:11Z2023-01-01T00:00:00ZThe crystal structure of fac-tricarbonyl((pyridin-2-yl)methanamino-κ2N,N′)-((pyridin-2-yl)methanamino-κN)rhenium(I) nitrate,C15H16O3N4Re
Alexander, Orbett T; Ramoba, Lesetja V; Malan, Frederick P
Abstract: C15H16O3N4Re, triclinic, P1̄ (no. 2), a = 7.4939(2) Å, b = 10.1316(2) Å, c = 13.8351(3) Å, α = 103.453(2)°, β = 101.992(2)°, γ = 107.880(2)°, V = 926.98(4) Å3, Z = 2, Rgt(F) = 0.0341, wRref(F2) = 0.0861, T = 150 K.
2023-01-01T00:00:00ZParticle number concentration measurements on public transport in Bangkok, ThailandShallcross, Dudley EMatthews, James CChalida, ChompoobutNavasumrit, Panidahttp://hdl.handle.net/10566/92682024-01-26T00:00:41Z2023-01-01T00:00:00ZParticle number concentration measurements on public transport in Bangkok, Thailand
Shallcross, Dudley E; Matthews, James C; Chalida, Chompoobut; Navasumrit, Panida
Traffic is a major source of particulate pollution in large cities, and particulate matter (PM) level in Bangkok often exceeds the World Health Organisation limits. While PM2.5 and PM10 are both measured in Bangkok regularly, the sub-micron range of PM, of specific interest in regard to possible adverse health effects, is very limited. In the study, particle number concentration (PNC) was measured on public transport in Bangkok. A travel route through Bangkok using the state railway, the mass rapid transport underground system, the Bangkok Mass Transit System (BTS) Skytrain and public buses on the road network, with walking routes between, was taken whilst measuring particle levels with a hand-held concentration particle counter. The route was repeated 19 times covering different seasons during either morning or evening rush hours.
2023-01-01T00:00:00Z