School of Science
http://hdl.handle.net/10500/2736
2017-05-25T06:58:48ZMethodology development of quality control, quality assurance and standards for Moringa oleifera seeds using liquid chromatography
http://hdl.handle.net/10500/22401
Methodology development of quality control, quality assurance and standards for Moringa oleifera seeds using liquid chromatography
Chokwe, Ramakwala Christinah
Natural products or traditional medicine has been used for centuries to treat various ailments by mankind. The World Health Organization estimates that in recent times 80% of people in emerging economies rely on traditional medicine as their primary health care [1]. However, unlike pharmaceutical products which have methods in place for quantification of the active compounds traditional medicine still requires a lot of focus in this area. Moringa oleifera is one of those species that have been used traditionally to cure various ailments for centuries. Even though extensive phytochemical and pharmacological studies have been conducted on the different parts of the plant, there is still no analytical method that enables the quantification of the compounds in the Moringa products in the market. The aim of this research was to develop an HPLC separation method that can be used to quantify the compounds found in the Moringa oleifera products.
Compounds were extracted from the seeds of Moringa oleifera using the maceration method with a mixture of water and ethanol (1:1 v/v). The compounds were isolated using preparative HPLC. The structures of the compounds were elucidated using FTIR, NMR and MS. An HPLC separation method for quantification of the isolated compounds was developed and validated. The method was applied to the crude extract to quantify the isolated compounds in the extract.
The following compounds 3-caffeoylquinic acid, 4-(α-L-Rhamnosyloxy) benzyl isothiocyanate, O-ethyl-[4-(α-L-Rhamnosyloxy) benzyl] thiocarbamate and O-butyl-[4-(α-L-Rhamnosyloxy) benzyl] thiocarbamate were isolated at percentage purities ranging from 90 to 99%. The HPLC separation method for quantification showed a linear relationship between peak area and concentration of the compounds with regression coefficients ranging from 0.9977 to 0.9994. The method is also precise with % RSD values between 0.01 and 1.16%. The method was shown to be specific to the compounds of interest. The percentage distribution of compounds in 50 mg of the seeds extract was between 0.25 and 1.10 % w/w.
This study successfully developed and validated an HPLC separation method for four compounds found in the seeds of Moringa oleifera and quantified them in the crude extract of the seeds found in Zambia. This method can be used for identification and quantification of these four compounds in any of the Moringa products. As far as it could be ascertained this is the first time that such a method has been developed for these compounds
2016-05-01T00:00:00ZUnderstanding patterns of aggregation in count data
http://hdl.handle.net/10500/22067
Understanding patterns of aggregation in count data
Sebatjane, Phuti
The term aggregation refers to overdispersion and both are used interchangeably in this thesis. In addressing the problem of prevalence of infectious parasite species faced by most rural livestock farmers, we model the distribution of faecal egg counts of 15 parasite species (13 internal parasites and 2 ticks) common in sheep and goats. Aggregation and excess zeroes is addressed through the use of generalised linear models. The abundance of each species was modelled using six different distributions: the Poisson, negative binomial (NB), zero-inflated Poisson (ZIP), zero-inflated negative binomial (ZINB), zero-altered Poisson (ZAP) and zero-altered negative binomial (ZANB) and their fit was later compared. Excess zero models (ZIP, ZINB, ZAP and ZANB) were found to be a better fit compared to standard count models (Poisson and negative binomial) in all 15 cases. We further investigated how distributional assumption a↵ects aggregation and zero inflation. Aggregation and zero inflation (measured by the dispersion parameter k and the zero inflation probability) were found to vary greatly with distributional assumption; this in turn changed the fixed-effects structure. Serial autocorrelation between adjacent observations was later taken into account by fitting observation driven time series models to the data. Simultaneously taking into account autocorrelation, overdispersion and zero inflation
proved to be successful as zero inflated autoregressive models performed better than zero inflated models in most cases. Apart from contribution to the knowledge of science, predictability of parasite burden will help farmers with effective disease management interventions. Researchers confronted with the task of analysing count data with excess zeroes can use the findings of this illustrative study as a guideline irrespective of their research discipline. Statistical methods from model selection, quantifying of zero inflation through to accounting for serial autocorrelation are described and illustrated.
2016-06-01T00:00:00ZQuasi-orthogonality and real zeros of some 2F2 and 3F2 polynomials
http://hdl.handle.net/10500/21949
Quasi-orthogonality and real zeros of some 2F2 and 3F2 polynomials
Johnston, Sarah Jane; Jordaan, Kerstin
In this paper, we prove the quasi-orthogonality of a family of 2F2 polynomials and several classes of 3F2 polynomials that do not appear in the Askey scheme for hypergeometric orthogonal polynomials. Our results include, as a special case, two 3F2 polynomials considered by Dickinson in 1961. We also discuss the location and interlacing of the real zeros of our polynomials.
2015-01-01T00:00:00ZVariants of P-frames and associated rings
http://hdl.handle.net/10500/21795
Variants of P-frames and associated rings
Nsayi, Jissy Nsonde
We study variants of P-frames and associated rings, which can be viewed as natural
generalizations of the classical variants of P-spaces and associated rings. To be more
precise, we de ne quasi m-rings to be those rings in which every prime d-ideal is either
maximal or minimal. For a completely regular frame L, if the ring RL of real-valued
continuous functions of L is a quasi m-ring, we say L is a quasi cozero complemented
frame. These frames are less restricted than the cozero complemented frames. Using
these frames we study some properties of what are called quasi m-spaces, and observe
that the property of being a quasi m-space is inherited by cozero subspaces, dense z-
embedded subspaces, and regular-closed subspaces among normal quasi m-space.
M. Henriksen, J. Mart nez and R. G. Woods have de ned a Tychono space X to be a
quasi P-space in case every prime z-ideal of C(X) is either minimal or maximal. We call a
point I of L a quasi P-point if every prime z-ideal of RL contained in the maximal ideal
associated with I is either maximal or minimal. If all points of L are quasi P-points, we
say L is a quasi P-frame. This is a conservative de nition in the sense that X is a quasi
P-space if and only if the frame OX is a quasi P-frame. We characterize these frames
in terms of cozero elements, and, among cozero complemented frames, give a su cient
condition for a frame to be a quasi P-frame.
A Tychono space X is called a weak almost P-space if for every two zero-sets E and
F of X with IntE IntF, there is a nowhere dense zero-set H of X such that E F [H.
We present the pointfree version of weakly almost P-spaces. We de ne weakly regular
rings by a condition characterizing the rings C(X) for weak almost P-spaces X. We
show that a reduced f-ring is weakly regular if and only if every prime z-ideal in it which contains only zero-divisors is a d-ideal. We characterize the frames L for which the ring
RL of real-valued continuous functions on L is weakly regular.
We introduce the notions of boundary frames and boundary rings, and use them to
give another ring-theoretic characterization of boundary spaces. We show that X is a
boundary space if and only if C(X) is a boundary ring.
A Tychono space whose Stone- Cech compacti cation is a nite union of closed subspaces
each of which is an F-space is said to be nitely an F-space. Among normal spaces,
S. Larson gave a characterization of these spaces in terms of properties of function rings
C(X). By extending this notion to frames, we show that the normality restriction can
actually be dropped, even in spaces, and thus we sharpen Larson's result.
2015-12-01T00:00:00Z