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Design of a Flood Water Powered Water Pump
No full textProceedings from the First International Conference on
Appropriate Technology,
Bulawayo, Zimbabwe
July 15-17, 2004The paper set to discuss the research to develop a machine that collects water from
flooded rivers and pumps it to a reservoir so that it can be used to water crops during
the interludes of dry spells that characterize the Zimbabwe rain season. This water is
not necessary intended to irrigate the crop on full scale, but just to bridge the crop and
sustain it during the critical weeks of the dry spells which usually stresses the crop
beyond recovery even after the rains resume.
The simple machine designed relies totally on the force of the flood water to pump
water from the river and send it to the reservoir, thus making it possible for the
machine to be used in the rural areas where there is no electricity. The cost of the model
that was built is given as well as the pictorial view of the model
Molecular characterisation of Armillaria species from Zimbabwe
No full textResearch articleArmillaria species are amongst the most important pathogens of trees and have a world-wide distribution. In recent
years, the taxonomy of Northern Hemisphere Armillaria spp. has been extensively treated, but those occurring in Africa
are poorly known. Previously, isolates of Armillaria from Zimbabwe have been grouped based on morphology and
biochemical tests. In this study, six isolates representing the three previously characterized groups of Armillaria spp.
occurring in Zimbabwe were analysed using DNA-based techniques. Three distinct clusters emerged from both
PCR?RFLP and analysis of sequence data for the IGS-1 rRNA operon. The three groups corresponded to those
previously identified based on morphology and biochemical tests. Differences in IGS-1 sequences strongly suggest that
the Zimbabwean groups represent three distinct taxa. Isolates belonging to Group I, previously assumed to be to
A. heimii, were similar to those identified as A. fuscipes from South Africa and La Reunion. Group II isolates
resided in a clade apart from all other isolates and appear to represent A. heimii. The remaining isolates residing in
Group III clustered with isolates from Zambia and Cameroon. These are different from A. heimii and A. fuscipes and
apparently represent an undescribed taxon
Activities of glutamate dehydrogenase and aspartate and alanine aminotransferases in freshwater snails Helisoma duryi and Lymnaea natalensis exposed to copper.
No full textIn this paper we investigate the potential of glutamate dehydrogenase (GDH) and aspartate and alanine aminotransferases (AST and ALT) as biomarkers of water pollution due to copper in the freshwater snails Helisoma duryi and Lymnaea natalensis. Snails were dosed with copper(II) ion concentrations of 0.01, 0.1 and 1 mg kg(-1) breeding water for a period of 96 h, after which those surviving were shelled. The copper content in the breeding water, in whole snail tissue and in the snail shells was determined at the end of the period of exposure. For enzyme determinations, whole snail tissue was first homogenized and fractionated by centrifugation at 500 g to remove the nuclei. The resulting supernatant was then centrifuged at 10,000 g to give a pellet fraction representing the mitochondrial fraction and a supernatant representing the cytosolic fraction. Copper was very toxic to both snail species at concentrations above 0.2 mg l(-1), with only 3% of the Helisoma and 12% of the Lymnaea surviving at concentrations of approximately 1 mg l(-1). The copper content in the shells and tissues of snails rose with increasing copper concentration in the breeding water, and was 2.1- to 4.9-fold in snails exposed to copper ion at a dose of 1 mg kg(-1) water compared with undosed snails. Similarly, the activities of GDH and AST rose by up to 4.7-fold in the homogenate and the mitochondrial and cytosolic fractions with increasing concentrations of copper. These activities, however, fell at copper concentrations of approximately 1 mg l(-1), which coincided with massive death of snails. Mitochondrial ALT disappeared at copper ion concentrations of approximately 0.2 mg l(-1) for Lymnaea and 1 mg l(-1) for Helisoma, possibly indicating mitochondrial degeneration. These results show that GDH, AST and ALT have the potential to be biomarkers of sublethal copper pollution in these two snail species, since their activities were significantly altered by low copper concentrations.Sida/SAREC Water Projec
A simulation model of draught animal power in smallholder farming systems. Part I: Context and structural overview
No full textThis paper presents the context, approach, and overview of a computer based draught animal power simulation model named Draught Animal Power Simulator (DAP-Simulator). The model was developed using data from literature and modified components and modules of existing models. The overall objective of this study was to provide a decision support system for agricultural planners and development agencies in the evaluation of different strategies of improving the efficiency of DAP use in crop production. The model was coded in Turbo PASCAL 7.0 and implemented in the interactive modelling package, DRIVER. The traction module of the PCHERD model was modified and interfaced with dynamic, empirical and deterministic sub-routines that simulate energy requirements for work (ploughing or carting loads), maintenance, pregnancy, lactation, feed intake, digestion and absorption, and daily weight changes. It can be used as a tool for the strategic use of draught animals, estimating effects of work stress on animal performance and calculation of work requirements. The development of this model indicated that more research work needs to be carried out in quantifying rolling resistance; estimating specific soil resistance, energy requirements for maintenance in Bos indicus cattle; effects of disease; animal behaviour (temperament); and partition of endogenous and exogenous energy. A subsequent paper will present detailed descriptions of model validation, sensitivity analysis, and application
Prevalence of Paramphistomes in Mashonaland West, Central, and East, and Midlands Provinces, Zimbabwe
No full textJournal article.Paramphistomes were collected from cattle from various localities in Mashonaland West,
Central, and East and Midlands Provinces. After slaughter, their rumens and reticulum were
cut open and examined for paramphistomes. Identifications were based on the morphological
structuresand measurementsof diagnosticfeaturesfrom flattened and median sagittal sections.
Analysis of the structures of the acetabulum, pharynx, and genital atrium revealed the
following parasites in the area, Paramphistomum microbothrium, P. clavula, Calicophoron
calicophorum, C. raja, and Gigantocotyle symmeri. The average number of cattle found
infected annually was 29.39% with an upper limit of the range of around 69%. Parasite
loads and damage to tissues were not serious in most cases, except in a few severe cases
where the papillae were damaged and a catarrhal pus-like exudate was noticed on the mucos
Inhibition of Glutathione S-Transferases by antimalarial drugs possible implications for circumventing anticancer drug resistance.
No full textAn approval letter from editors is attached to the articleA strategy to overcome multidrug resistance in cancer
cells involves treatment with a combination of the antineoplastic
agent and a chemomodulator that inhibits the activity
of the resistance-causing protein. The aim of our study was to
investigate the effects of antimalarial drugs on human recombinant
glutathione S-transferase (GSTs) activity in the
context of searching for effective and clinically acceptable
inhibitors of these enzymes. Human recombinant GSTs heterologously
expressed in Escherichia coli were used for inhibition
studies. GST Al-l activity was inhibited by artemisinin
with an IC,, of 6 pM, whilst GST MI-l was inhibited by
quinidine and its diastereoisomer quinine with IC5,s of I2 pM
and 17 pM, respectively. GST M3-3 was inhibited by tetracycline
only with an IC,, of 47 pM. GST PI-l was the most
susceptible enzyme to inhibition by antimalarials with IC,,
values of I, 2, 1, 4, and 13 pM for pyrimethamine, arteniislnin,
quinidine, quinine and tetracycline, respectively. The
IC,, values obtained for artemisinin, quinine, quinidine and
tetracycline are below peak plasma concentrations obtained
during therapy of malaria with these drugs. It seems likely,
therefore, that GSTs may be inhibited in vivo at doses normally
used in clinical practice. Using the substrate ethacrynic
acid, a diuretic drug also used as a modulator to overcome
drug resistance in tumour cells, GST PI-l activity was inhibited
by tetracycline, quinine, pyrimethamine and quinidine
with IC,, values of 18, 27, 45 and 70 pM, respectively. The
ubiquitous expression of GSTs in different malignancies suggests
that the addition of nontoxic reversing agents such as
antimalarials could enhance the efficacy of a variety of alkylating
agents.International Program in Chemical Sciences (IPICS), Uppsala University, Uppsala, Sweden; Research Board University of Zimbabwe, Harare Zimbabwe
The effect of air sparging on the electrical resolution of water-in-oil emulsions
No full textResearch ArticleA novel process is described in which the resolution of a stable water-in-oil emulsion is augmented by the simultaneous use of
pulsed DC electric 1elds and mild bubbling of the emulsion with air. The work has indicated that there is a synergistic effect of
air sparging on demulsi1cation in the electric 1eld and that the maximum emulsion resolution requires the voltage to be pulsed
with optimum frequency. Emulsion resolution was found to increase steadily with increasing air 5ow rate until a maximum value
is reached after which the extent of phase separation starts to fall rapidly with further increase in the air 5ow rate. The electrical
resolution was best (79% resolution) when the ratio of air to emulsion 5ow rate (volumetric) in the coalescer was about 120 : 1.Engineering and Physical Sciences Research Counci
Proposed Reductive Metabolism of Artemisinin by Glutathione Transferases in vitro
No full textjournal for proposed reductive metabolismArtemisinin is a sesquiterpene lactone containing an
endoperoxide bridge. It is a promising new antimalarial
and is particularly useful against the drug resistant
strains of Plasmodium fakiparum. It has unique antimalarial
properties since it acts through the generation of
free radicals that alkylate parasite proteins. Since the
antimalarial action of the drug is antagonised by
glutathionc and ascorbate and has unusual pharmacokinetic
properties in humans, we have investigated if
the drug is broken down by a typical reductive reaction
in the presence of glutathione transferases. Cytosolic
glutathione transferases (GSTs) detoxlfy electrophilic
xenobiotics by catalysing the formation of glutathione
(GSH) conjugates and exhibit glutathione peroxidase
activity towards hydroperoxides. Arternisinin was
incubated with glutathione, NADPH and glutathione
reductase and G~TiSn a coupled assay syste&analogous
to the standard assav scheme with cumene hv,d rover- L oxide as a substrate df GSTS. Arternisinin was shown to
stimulate NADPH oxidation in cytosols from rat liver,
kidney, intestines and in affinity purified preparations
of GSTs from rat liver. Using human recombinant GSTs
hetelorogously expressed in Escherichia coli, artemisinin
was similarly shown to stimulate NADPH oxidation
with the highest activity observed with GST MI-1.
Using recombinant GSTs the activity of GSTs with artemisinin
was at least two fold higher than the reaction
with CDNB. Considering these results, it is possible that
GSTs may contribute to the metabolism of artemisinin
in the presence of NADPH and GSSG-reductase We
propose a model, based on the known reactions of
GSTs and sesquiterpenes, in which (1) artemisinin
reacts with GSH resulting in oxidised glutathione; (.2)
the oxidised glutathione is then converted to reduced
glutathione via glutathione reductase; and (3) the latter
reaction may then result in the depletion of NADPH
via GSSG-reductase. The ability of artemisinin to react
with GSH in the presence of GST may be responsible
for the NADPH utilisation observed in vitro and suggests
that cytosolic GSTs are likely to be contributing to
metabolism of artemisinin and related drugs in vivothe support of the International Program in
Chemical Sciences (IPICS), Uppsala University,
Sweden, The Swedish Natural Science Researc
Customisation in Cross-Assembler Design for the PIC16F872
No full textThe paper describes the development of a cross-assembler known as MCASM which enables programming of the PIC16F872 in a language similar in style to that of the Intel ASM51. The work was instigated by the needs of students in the national university of science and technology for a cheap and versatile means of assembly for this processor. Customised features of the software are described
A Comparison Of Some Antioxidant Enzymes In African Catfish Collected From Umguza And Mzingwane Dams, Bulawayo, Zimbabwe
No full textPaper presented at the Biochemistry and Molecular Biology Society of Zimbabwe, 27 OctoberThis study presents preliminary data of two biochemical parameters analyzed in fish tissues from Umguza and Mzingwane Dams as a function of pollution. The levels of pollution in these dams was assessed by measuring concentration of pesticide and heavy metal residues in water as well as fish tissues. Organophosphate pesticides were not detectable in either water
or fish muscle from either of the dams. Organochlorine pesticides, namely, aldrin, dieldrin and DDT were found in Umguza fish muscles at levels of 0.017 mg/kg, 0.016 mg/kg and 0.107 mgikg respectively. Only trace amounts of the organochlorine pesticides were determined in Mzingwane Dam. The levels of heavy metals (zinc, lead,nickel and copper) in fish tissue and water collected from both dams were similar. The activity of catalase was elevated in the liver of catfish from Umguza Dam (relatively more contaminated with respect to organochlorine pesticides). However, catalase activity in the gills of fish obtained from Mzinf:,TWane Dam was higher compared to the gills of fish obtained from Umguza Dam. DT diaphorase activity was lower in both livers and gills of fish obtained from Umguza Dam. These data suggest that organochlorine pesticides cause oxidative stress as evidenced by enhanced catalase activity. Glutathione peroxidase and superoxide dismutase activity as well
as levels of glutathione and malondialdehyde levels will be measured in order to get a more complete picture of the antioxidant status of the fish from these dam