Multicomponent mass transport modeling of water desalination by reverse osmosis including ion pair formation.

Reverse Osmosis (RO) is one of the main membrane technologies currently used for the desalination of seawater and brackish water to produce freshwater. However, the mechanism of transport and separation of ions in RO membranes is not yet fully understood. Besides acid-base reactions (i.e., including the H+-ion), at high concentrations, the salt ions can associate and form ion pairs. In this study, we investigate how to include the formation of these ion pairs in the extended Donnan steric partitioning pore model. We study the desalination of a water source where three ion pairs can be formed (NaCl, MgCl+, and MgCl2) and also include water self-dissociation and the carbonate system. The model assumes infinitely fast reactions, which means that the participating ions are locally at chemical equilibrium with one another. A square stoichiometric reaction matrix composed of active species, moieties, and reactions is formulated. As the final constraint equation, we use the charge balance. The model predicts profiles in concentration, flux, and reaction rates across the membrane for all species and calculates the retention per group of ions. Ion pair formation has an influence on the fluxes of individual ions and therefore influences the retention of ions.

Transcriptome Sequencing Reveals a Complete Genome Sequence of Cowpea Aphid-Borne Mosaic Virus from Passion Fruit in Kenya.

Analysis of transcriptome sequencing (RNA-Seq) data revealed a complete Cowpea aphid-borne mosaic virus (CABMV) genome from virus-infected passion fruit in Kenya. We compared it with six complete CABMV genomes, one each from Zimbabwe and Uganda and two each from Brazil and India. The Zimbabwean isolate CABMV-Z was the closest, with 83.0% nucleotide identity.

Harlequin ichthyosis in an African child: case report.

Severe congenital skin abnormalities are a rare event. This case is unique in that it is a case of harlequin ichthyosis in sub-sahara Africa in a child of African origin and elaborates the challenges faced in its management. We present a neonate who was managed for this condition at Chogoria Mission Hospital. In presenting this case, we aim to sensitise healthcare providers to promptly recognise and manage this rare skin condition.

Indoor air pollution in a Kenyan village.

In April 1986, a study was carried out within rural households in Maragua area, Muranga District, Republic of Kenya, to assess the degree of indoor air pollution and to find its relationship, if any, to acute respiratory infections (ARI) among children aged below 5 years within the study. This study was carried out within an ongoing aetiological and epidemiological community study on ARI as a collaborative effort between the Department of Paediatrics, University of Nairobi; the Department of Chemistry, Kenyatta University; the Department of Environmental Sciences, Agricultural University, Wagenigen, The Netherlands; the World Health Organization; and the Ministry of Health, Republic of Kenya. Repeated 24 hour measurements of respirable suspended particles (RSP) and nitrogen dioxide (NO2), were carried out in 36 randomly selected houses where most of the cooking was done on open fires using firewood and crop residues as fuel. Data on house characteristics and activity in the study were gathered by questionnaire. The mean of 24 hour average RSP concentration (1400mg/m3), average during the 7 hours of daily burning (3000-4000mg/m3), and evening peak levels (up to 3600mg/m3) indicate that deleterious health effects due to exposure to excessive levels of toxic pollutants in smoke from biomass combustion are likely to occur especially among pre-school children and women. Concentrations of selected polycyclic hydrocarbons in the particulate material were found to be high. It was not possible to demonstrate a relationship between the indoor air pollution and episodes of ARI partly because of small sample size and also the more or less homogeneous nature of pollution among all the households.