Published Article / A stream flow at an outlet of a catchment can be entirely a base flow or direct flow or a combination of both. The base flow component of a stream is mainly contributed from the ground water storage which often is an open aquifer whereas the direct flow component is mainly the result of a direct response of a rainfall event. The Upper Modder river basin catchment is considered to be the origin of the Modder River which supplies water to Rustfontein Dam, situated at the outlet of the C52A with an area of 928 km2. Nine years of daily stream flow showed a continuous none zero discharge throughout the year. During the rainy season the discharge of the stream increases significantly. Thus, it is necessary to separate the direct and base flow of the stream in order to understand the important component that is more likely to be affected by different land use changes in a catchment. The Modder river daily mean flow at the inlet of Rustfontein dam (in Central South Africa) was analysed using four base flow separation methods, the Nathan & McMahon (N&M), the Chapman, Smakhtin & Watkins (S&W) method and the frequency duration analysis. All the methods gave higher percentage of the low flow component, except for the S&W method which underestimated it. The N&M filtering equation gave base flow components greater than 66% in 1999 and increased to 84% in 2007 while the Chapman equation revealed 65% and 74% in 1999 and 2007, respectively. Similarly, the frequency duration analysis gave 62% in 1999 and increased to 79% in 2007. The frequency duration analysis gave up to 13% lower percentage than the N&M (1990) filtering equation. The nine year base flow averages are 69%, 69% and 75% for frequency duration analysis, Chapman (1999) and N&M (1990) filtering equations, respectively. The result revealed that the Modder River is largely supplied by the ground water discharge. The result seemed to concur with the fact that for a semi-arid catchment such as the Modder river basin, with an average annual runoff coefficient of approximately 6%, the contribution of annual rainfall to direct runoff is very minimal.

Dissertation submitted in fulfilment of the requirements for the Masters Degree in Technology: Chemistry, Durban University of Technology, 2009. / The activity coefficients at infinite dilution ( γ13 ) were calculated for alkanes, alkenes, cycloalkanes, alkynes, ketones, alcohols and aromatic compounds from gas liquid chromatography (glc) measurements at three temperatures (303.15 and 313.15 and 323.15) K. The γ13 values were calculated from the retention data for two ionic liquids (ILs) with the same cation but different anions. The ionic liquids: [methyltrioctylammonium bis(trifluoromethylsulfonyl)imide and methyltrioctylammonium thiosalicylate] were used as the stationary phase. The γ13 data for methyltrioctylammonium thiosalicylate were higher than for methyltrioctylammonium bis(trifluoromethylsulfonyl)imide. For each temperature and each ionic liquid, γ13 values were determined for two columns and the average γ13 values were used for the calculation of the partial molar excess enthalpies at infinite dilution, H E 1 Δ , using the Gibbs-Helmholtz equation. Graphs of In γ13 vs 1/T were plotted to determine H E 1 Δ at T = 303.15 K. The selectivity, S12 , value for the hexane/benzene separation was calculated from the ratio of the avarage γ13 values to determine the suitability of the ILs as an entrainer for extractive distillation in the separation of aromatic and aliphatic compounds.The S12 values were also compared to the literature values for other ionic liquids. It was found that the longer chain alkyl group attached to the cation or anion gave lower S12 values. Both ILs have S12 values greater than one and in theory can be used as an entrainer for the hexane/ benzene separation. The capacities at infinite dilutions, k1 , were also calculated from the inverse of the avarage γ13 values for each IL at each temperature. / National Research Fund; Postgraduate Development and Support Directorate.

Submitted in fulfilment of the requirements for the degree of Master of Engineering, Durban University of Technology, Durban, South Africa, 2015. / Fermentation processes are vital for the production of numerous bioproducts. Fermentation being the mass culture of micro – organisms for the production of some desired product, is an extensive field, with immense prospects for study and improvement. Enzyme production is of significance as these proteins are biological catalysts, finding niches in numerous industries, xylanase for example is utilized in the pulp and paper, animal feed, biofuel and food production processes. During enzyme production, a critical step is biomass separation, whereby the valuable product, the enzyme, is removed from the broth or micro – biological culture before it is denatured. This is typically achieved via centrifugation. The aim of this study was to develop and evaluate a submerged membrane fermenter system with the specific outcome of increasing the rate of production of xylanase, from the thermophilic fungal species Thermomyces lanuginous DSM 5826. Preliminary shake flask experiments were performed to determine the optimal production conditions, followed by partial characterization of the enzyme. A bioreactor was then fabricated to include a flat sheet membrane module, with outlets for permeate and broth withdrawal and inlets for feed and sterile air input. Experiments were conducted to determine the optimal dilution rate for maximum volumetric productivity. Results from the shake flask experiments indicated that the best conditions for xylanase production, yielding xylanase activity of 5118.60 ± 42.76 U.mL-1 was using nutrient medium containing beechwood xylan (1.5 % w/v), yeast extract (1.5 % w/v), potassium dihydrogen phosphate (0.5 % w/v), adjusted to a pH of 6.5 and inoculated with 1.0 mL of spore solution, rotating in a shaking incubator set to 150 rpm at 50 °C. Apart from analysis of the effect of the carbon source on xylanase activity, coarse corn cobs were used in the shake flask experiments as a cost saving initiative. The pH optima was determined to be 6.5 while the temperature optima of the enzyme was 70 °C. SDS PAGE analysis revealed that the molecular weight of the enzyme was between 25 and 35 kDa and qualitative analysis via a zymogram revealed clear zones of hydrolysis on a xylan infused agarose gel. During short run membrane fermenter experiments the percentage increase in enzyme activity between the batch operation (610.58 ± 34.54 U.mL-1) and semi – continuous operation (981.73 ± 55.54 U.mL-1) with beechwood xylan nutrient replenishment was 60.78 %. The maximum volumetric productivity achieved with beechwood supplementation after 192 hours in semi – continuous operation (5.32 ± 0.30 U.mL-1.hr-1) was 2.1 times greater than that of batch operation (2.54 ± 0.14 U.mL-1.hr-1) which equates to an increase of 110.28 % in productivity measured at its peak. The increase in total activity between batch (610 576.92 U) and beechwood xylan medium supplemented semi – continuous mode (1 184 937.50 U) resulted in a 94.07 % increase. During long run experimental periods, the increase in production of xylanase between the batch (873.26 ± 61.78 U.mL-1) and the xylan medium membrane system (1522.41 ± 107.65 U.mL-1) was determined to be 74.34 % while an overall average increase in productivity between the batch and xylan fed membrane system was 43.25%. The total enzyme activity with in membrane mode with beechwood xylan nutrient medium feed was 160 % greater than the batch process offering a 2.6 – fold increase. Experiments where de – ionized water was alternated with beechwood xylan nutrient medium had no significant impact on the productivity or enzyme activity. The optimal dilution rate for maximum volumetric productivity as determined to be 0.0033 hr-1. The results are indicative of the potential viability of such a design, yielding the desired outcome of a membrane integrated system to significantly increase the production of enzymes during fermentation.

Thesis (MScEng)--University of Stellenbosch, 2001. / ENGLISH ABSTRACT: Ferrohydrostatic separation (FHS) of materials is a float and sink technique which utilizes ferrofluid exposed to a non-homogeneous magnetic field. The efficiency of material separation depends on numerous variables. The most important variables, which were investigated individually, are the effects of moisture content, ferrofluid level, feedrate, particle size and material density distribution on separation efficiency. It is important to recover and recycle the ferrofluid attached to the products of separation so as to reduce the cost of the FHS technology and the amount of kerosene disposed of to the environment. This prompted research into some of the factors affecting ferrofluid recovery. The factors that were investigated are the effects ofFHS operation, material moisture content, particle size and porosity. The separation efficiency was found to be dependent on all the variables investigated. The effect of material moisture content is less pronounced for particles larger than 2.8 mm. This implies that wet feed material should be screened before ferrohydrostatic separation and material which particle size is less than 2.8 mm should preferably be treated dry. Wet material (less than 2.8 mm) floats, even though its density is greater than the cut-point density. This is owing to the immiscibility of the water coating the particles and the kerosene-based ferrofluid used for separation. It was found that the effect of ferrofluid level on separation efficiency is a function of both the density difference of the particles to be separated and the particle size. Separation efficiency as a function of ferrofluid level is poor for particles larger than 2 mm and is good when the density difference of the material to be separated is high, for instance between 2700 kg/nr' and 3530 kg/nr'. This shows that for efficient separation of coarse particles and near density material (material with density close to the cut-point density), the ferrofluid level should be controlled, preferably close to the maximum possible level. The effect of feedrate on separation efficiency is also a function of the densities of the particles to be separated. An increase in feedrate leads to poor separation for particles with densities close t~ each other. This implies that separation of near density material requires accurate feedrate control. It has been shown from simulation and modelling that the effective cutpoint density changes as the particle moves through the chamber until it eventually reaches its terminal velocity, given that the chamber is of sufficient size for this to occur. The effective cut-point density increases to the maximum as the particle enters the ferrofluid pool but settles down to a relative constant once the particle has reached its terminal velocity. The effective cut-point density was shown to decrease with an increase in particle magnetisation. It was found that this decrease in the cut-point density determines the density difference (difference between two particles) achievable when non-magnetic material is treated together with magnetic material. It is therefore important to magnetically scalp the feed material for efficient separation. When the material is not scalped, magnetic and nonmagnetic material with the same density might report to different density fractions, which leads to poor separation. This magnetic contribution to the effective density can be utilised in the separation of material with same density but different magnetisation. The efficiency offerrofluid recovery was found to be dependent on all the variables investigated. The amount of ferrofluid drawn from the FHS separator was found to decrease with an increase in the magnetic field. Furthermore, the amount of ferrofluid that remains attached to the particles after allowing ferrofluid to drain from the material is the same as that attached to the FHS products of separation at high magnetic fields. This shows that it is important to operate the ferrohydrostatic separator at high magnetic fields in order to attract most of the ferrofluid back to the separator. T-heamount of ferrofluid adsorbed onto and absorbed by the particles was found to decrease with an increase in the material moisture content. This is due to two factors. The first is that water occupies the vacant pores in the material. The second is that water forms a layer on the particle surface which is immiscible with kerosene-based ferrofluid. This phenomenon leads to a reduction in cost of the ferrohydrostatic separation technology when wet material as opposed to dry material is treated. As already described coarse material larger than 2.8 mm can be treated wet without detrimental effects on separation. For -8+4 mm particles, the ferrofluid loss ranges from 0.6 down to 0.14 kg/tonne of feed for 0 to 10 % material moisture content respectively. The amount of ferrofluid lost per tonne of feed was found to range from 0.73 to 0.56 kg for-O.85+O.5 mm to -12+8 mm particle sizes respectively. The increase in ferrofluid loss in small particles is due to the increase in surface area in small particles for ferrofluid adsorption. The increase in porosity increases the amount of ferrofluid lost due to the difficulties in recovering ferrofluid embedded in the pores of the particles. Adding water to coarse material lowers the amount of ferrofluid lost by reducing porosity. Modelling the amount of ferrofluid lost, as a function of particle size and porosity, would assist in determining the amount of ferrofluid required to treat a known amount of material. The quality of ferrofluid recovered was found to be the same as that initially used for material separation. This implies that the separation efficiency would not be affected by the use of recycled ferrofluid. / AFRIKAANSE OPSOMMING: Ferro-hidrostatiese skeiding van materiale is 'n flotasie (dryf) en besinkingstegniek wat gebruik maak van ferro-vloeistof wat blootgestel is aan 'n magnetiese veld. Die effektiwiteit van die materiaal skeiding is afhanklik van verskeie veranderlikes. Die belangrikste veranderlikes wat die skeidingseffektiwiteit beïnvloed is individueel bestudeer, naamlik voginhoud, ferro-vloeistof vlak, voertempo, partikelgrootte en materiaal digtheid verspreiding. Dit is belangrik om die ferro-vloeistof te herwin en te hergebruik om die koste van die proses en tegnologie te verminder en dus ook die hoeveelheid keroseen wat aan die omgewing blootgestel is. Dit het navorsing tot gevolg gehad oor die faktore wat ferro-vloeistofherwinning beïnvloed. Hierdie.faktore wat ondersoek is in hierdie studie is materiaal voginhoud, partikelgrootte en porositeit. Die skeidingseffektiwiteit was afhanklik van al die faktore wat ondersoek is. Die effek van materiaal voginhoud was minder beduidend vir partikels groter as 2.8 mm. Dit wys dat nat voermateriaal moet gesif word voor ferro-hidrostatiese skeiding, en materiaal met 'n partikelgrootte kleiner as 2.8 mm moet verkieslik gedroog word. Nat materiaal (minder as 2.8 mm) floteer selfs as die digtheid groter is as die snypunt digtheid. Dit is as gevolg van ondeurlaatbaarheid van die water wat die partikels bedek en die keroseen basis ferro-vloeistofwat gebruik word vir die skeiding. Dit is gevind dat die invloed op die skeidingseffektiwiteit van die ferrovloeistof vlak is 'n funksie van beide die digtheid van die partikels wat geskei word. Die partikelgrootte skeidingseffektiwiteit as 'n funksie van die ferro-vloeistof vlak, is swak vir partikels groter as 2 mm en is goed wanneer die digtheid verskil van die materiaal wat geskei moet word, hoog is, byvoorbeeld 2 700 kg/nr' en 3 530 kg/nr'. Dit wys dat vir die effektiewe skeidings vir groter partikels en naby digtheid materiaal (materiaal net 'n digtheid nabyaan die snypunt digtheid), moet die ferro- . vloeistofvlak baie goed beheer word, gewoonlik naby die maksimum vlak moontlik. Die effek van voertempo op die effektitiwiteit van skeiding is ook 'n funksie van die digtheid van die partikels wat geskei moet word. 'n Toename in die vloeitempo lei tot 'n swak skeiding van partikels met digthede wat naby mekaar lê. Dit wys weer daarop dat die skeiding van naby digtheid materiaal het die akkurate beheer van voertempo tot gevolg. Dit is gevind deur simulasie en modulering dat die effektiewe snypuntdigtheid verander soos die partikel deur die kamer beweeg totdat dit uiteindelik sy finale snelheid bereik (gegee dat die kamer groot genoeg is). Dit effektiewe snypunt digtheid verhoog tot 'n maksimum wanneer die partikel die ferro-vloeistof binne gaan, maar bereik na 'n kort tydperk 'n kostante waarde sodra die partikel sy finale snelheid bereik het. Die effektiewe snypunt digtheid verlaag met 'n toename in partikel magnetisme. Dit is gevind dat die afname in die snypunt digtheid bepaal die digtheidsverskil (verskil tussen twee partikels) wat bereikbaar is wanneer nie-magnetiese materiaal saam met magnetiese materiaal behandel word. Dit is dus belangrik om die voer materiaal magneties te skalpeer vir effektiewe skeiding. Wanneer die materiaal so behandel word, sal magnetiese en nie-magnetiese materiaal, met die dieselfde digthede, rapporteer in verskillende digtheidsfraksies wat sal lei tot swak skeiding. Die magnetiese bydrae tot die effektiewe digtheid kan gebruik word in die skeiding van materiaal met dieselfde digtheid, maar met verskillende magnetismes. Die effektiwiteit van ferro-vloeistof herwinning is afhanklik van al die veranderlikes wat ondersoek is. Die hoeveelheid ferro-vloeistof wat omtrek is van die ferro-hidrostatiese skeier verminder met 'n toename in die magnetiese veld. Verder is die ferro-vloeistof wat agterbly as gevolg van die feit dat hulle vas is aan die partikels na dreinering, dieselfde as die hoeveelheid wat vasgeheg is aan die die ferro-hidrostatisiese produkte van skeiding by hoë magnetiese velde. Dus is dit belangrik om die ferrohidrostatiese skeier te bedryf by hoë magnetiese velde om sodoende die meerderheid van die ferro-vloeistof in die skeier agter te laat bly. Die hoeveelheid ferro-vloeistof geadsorbeer aan en geabsorbeer deur die partikels verlaag met 'n toename in die materiaal voginhoud. Dit is gevolg van twee redes, nl. eerstens water wat die plek inneem van die oop porieë in die materiaal, en tweede is die feit dat water 'n lagie op die partikeloppervlakte vorm wat ondeurlaatbaar is vir keroseen-basis ferrovloeistof Dit lei tot die vermindering in koste van die ferro-hidrostatiese skeidingstegnologie wanneer nat materiaal in plaas van droë materiaal gebruik word. Soos alreeds genoem, partikels groter as 2.8 mm kan nat behandel word sonder enige negatiewe effekte op die skeiding. Vir -8+4 mm partikels is daar 'n ferro-vloeistofverlies van 0.6 tot 0.14 kg/ton voer vir' n 0-10% voginhoud. Die hoeveelheid ferro-vloeistof per ton voer materiaal wat verlore gaan wissel tussen 0.73 tot 0.56 kg vir -0.85+0.5 mm tot -12+8 mm partikelgroottes, respektiewelik. Die toename in ferro-vloeistofverlies by kleiner partikels is as gevolg van die toename in die oppervlakarea van kleinpartikels vir ferro-vloeistof adsorpsie. Daar is 'n toename in porositeit wat gepaard gaan met 'n toename in hoeveelheid in ferro-vloeistof wat verlore gaan as gevolg van probleme met die herwinning van ferro-vloeistof wat binne-in partikelporieë vasgevang IS. Die byvoeging van water by groter materiaal verlaag die hoeveelheid . ferro-vloeistofwat verlore gaan as gevolg van verminderde porositeit. Die modellering van die hoeveelheid ferro-vloeistof wat verlore gaan, as 'n funksie van die partikelgrootte en porositeit, sal help met die skatting van die hoeveelheid ferro-vloeistof benodig om 'n sekere hoeveelheid materiaal te behandel. Dit is gevind dat die kwaliteit van die ferro-vloeistof wat herwin word dieselfde is as die wat aanvanklik gebruik is vir die materiaal skeiding. Dit wys dat die skeidingseffektiwiteit beïnvloed nie die gebruik van gehersirkuleerde ferro-vloeistof nie.

Thesis (MScEng) -- Stellenbosch University , 2002. / ENGLISH ABSTRACT: The distillation process is the most widely used separating process in the chemical process industry. The optimal design of the distillation units can lead to reduced capital costs and improved energy utilisation. This is particularly the case for structured packed distillation column where design methods tend to over-predict the column efficiency. This work seeks to contribute to the development of a reliable mass transfer model for structured packing. A gas phase mass transfer correlation was developed based on the evaporation of pure components into an air stream. The mass transfer rates were measured in a short triangular wetted wall channel with a corrugated surface wall. The influence that the geometric configuration as well as surface structure has on the mass transfer rates was investigated. The channel geometry and surface wall structure resembled that of the structured packing (Flexipac 350Y). The influence of the channel geometry on the gas mass transfer rates was not significant except at low flow conditions. The liquid phase resistance was investigated for binary mixtures in the triangular wetted wall channel. It was found that the overall mass transfer rate decreased with increasing composition of the volatile component. The enhancement of the gas phase mass transfer rate masked the presence of the liquid resistance. ii The gas phase mass transfer correlations were used in the mass transfer model to predict the separation efficiency of a structured packed distillation column. The structured packing used to validate the mass transfer model was high-capacity Flexipac 350Y and normal Flexipac 350Y. The binary distillation experiments were done at total reflux conditions for the pressure range O.33-1atm. The accuracy of the separation efficiencies of the mass transfer model improved with increasing pressure for both materials. The mass transfer model was able to predict the variation of separation efficiencies with column loadings. / AFRIKAANSE OPSOMMING: Distillasie is die skeidingsmetode wat die meeste in die chemiese industrie gebruik word. Die optimale ontwerp van distillasie eenhede kan lei tot verlagings in kapitaalkostes en 'n verbeterde gebruik van energie. Dit is veral waar in die geval van kolomme met gestruktureerde pakking waar huidige ontwerpsmetodes, die kolomeffektiwiteit nie akkuraat beskryf nie. Hierdie studie het ten doelom 'n bydrae te lewer tot die ontwikkeling van 'n betroubare massa-oordragsmodel vir gestruktureerde pakking. 'n Gasfase massa-oordragskorrelasie is ontwikkel gebaseer op metings van die verdampingstempo van suiwer komponente in 'n lugstroom. Die massaoordragstempos is gemeet in 'n kort driehoekige benatle wand kanaal waarin die wand 'n bepaalde oppervlakprofiel het. Die invloed van beide die kanaalgeometrie en die oppervlakprofiel is ondersoek. Die geometrie en oppervlakprofiel is soorgelyk aan die van Flexipac 350Y gestruktureerde pakking. Die invloed van die kanaalgeometrie op die gasfase massaoordragstempos is slegs beduidend by lae vloeitempos. Die vloeistoffase weerstand vir binêre mengsels is ondersoek in die driehoekige kanaal. Dit is gevind dat die algehele massa-oordragstempo verlaag met 'n verhoging in die konsentrasie van die vlugtige komponent. Die verhoging in die gasfase massa-oordragstempo verberg die invloed van die vloeistoffase weerstand. Die gasfase massa-oordragskorrelasies is in 'n massa-oordragsmodel gebruik om die skeidingseffektiwiteit van gestruktureerde pakking in "n kolom te voorspel. Metings op hoë-kapasiteit Flexipac 350Y en normale Flexipac 350Y is gebruik om die modelvoorspellings te evalueer. Die binêre distillasies is by totale terugvloei gedoen in die drukbereik 0.33 - 1.0 atm. Daar is gevind dat die model meer akkuraat is by hoër drukke. Die massa-oordragsmodel is in staat om die variasie in skeidingseffektiwiteit met veranderende kolomlading te voorspel.

Bakgrund: I Sverige lever 35 % av barnen till separerade föräldrar i ett växelvis boende där de bor varannan vecka hos respektive förälder. Det finns en avsaknad av studier kring hur kosthållning fungerar vid växelvis boende. Det är en familjesituation som inte liknar någon annan: varken ensamstående förälder, enpersonshushåll eller ett flerfamiljhushåll i dess vanliga form. Förändringar i livet påverkar kostvanor. Boendeformen kan anses vara en sådan förändring och är därför värd att undersöka. Syftet: Studiens syfte var att utforska upplevelsen av matsituationen för föräldrar med delad vårdnad för barn i växelvis boende och belysa utmaningar kring kosthållning i en sådan familjesituation. Metod: Fyra män och tre kvinnor intervjuades utifrån en semistrukturerad intervjuguide om sina erfarenheter kring kosthållning som föräldrar i växelvis boende. Data analyserades med en kvalitativ innehållsanalys. Resultat: Det fanns speciella kvaliteter i familjesituationen som inte hittas i andra sorters hushåll. Det centrala var dualiteten i boendeformens struktur: vikten av fortsatt samarbete med den de separerat från, att tid och mat var viktigare med barnen än när de var ensamma och att det fanns en saknad efter barnen. Alla informanter uttryckte att mer tid och omtanke lades på förberedelser inför mat och måltider med barnen än när de var ensamma. Detta var oberoende av informantens kön. Slutsats: En dualitet framkom i hur kosten värderades olika mellan veckorna. Det finns en känslomässig och praktisk skillnad mellan veckorna som påverkar kosten och kan innebära att hälsan påverkas. Föräldrarnas tidigare könsroller verkar utjämnas. Växelvis boende är en variant av hushåll som skiljer sig tillräckligt mycket från andra sorters familjekonstellationer att det kan behövas mera forskning för att förstå hur föräldrarna påverkas ur ett kostperspektiv. / Background: In Sweden 35% of children with separated parents live in equally shared care on an every-other-week basis. There is a lack of studies in research addressing equally shared care and dietary concerns. It is a family situation like no other: neither a single-parent household, nor a single-member household, nor cohabitation in the usual sense. Life changes affect dietary habits. The shift to shared custody can be considered such a change and is therefore worth investigating. Objective: The aim was to assess how parents living in shared-care situations experienced dietary concerns, and to examine what challenges foodwise such a family construct may evoke. Method: Four men and three women were interviewed using a semi-structural interview guide about their dietary concerns as parents with equally shared care of children. Collected data from the interview were analysed with a qualitative content analysis method. Result: There were some special qualities in this family situation that are not found in other household settings. Most significant was the duality in the household structure: there was the importance of continued cooperation with the other parent, time and food were more important with the children than without them, and there was a sense of lack when the children were not there. All informants, regardless of gender, expressed that they spent much more time and care preparing meals during weeks with the children. Conclusion: There was a duality in the way dietary concerns were valued between weeks with and without children. There exists an emotional as well as a practical difference between the weeks which affect diet and possibly health. Gender roles of the parents are seemingly being equalized. Equally shared care differs enough as a household setting to warrant more studying to understand how parents are affected by this way of living.

Digital Wireless communications has been one of the fastest growing communication techniques during the last decade. Today there exists several different communication systems that use wireless techniques. They share one common property that they transmit data through a radio interface. The radio channel is a tough channel that will both distort and disturb the transmitted signal in various ways. In Jörgen Nordberg's PhD-thesis "Signal Enhancement in Wireless Communications Systems" several different signal enhancement schemes are presented. They have the objective to minimize the impact of the channel. The main part of this thesis presents work on interference cancellation, i.e. how to reduce the impact of other interfering signals on the channel of interest. This is achieved by utilizing the spatial domain, i.e. the receiver is using several antennas to receive the transmitted signals. By using a multitude of antennas techniques like spatial diversity, adaptive antenna arrays, signal separation and beamforming can be applied to combat the interfering signals. In the single antenna case there is often a need to do channel equalization. Since, channel equalization is an inverse filtering, it will often result in estimation of equalization filter parameters of very high order. To reduce the both the complexity and improve the convergence speed of the equalization filter parameter estimation subband processing techniques can be used. In this case the received signal is separated up into different frequency bands (subbands) and decimated according to the bandwidth of the signal. The channel equalization problem is then solved for each subband at a lower sampling rate. Hence, the channel equalization problem is transformed from estimating the parameters of a high order filter into estimating several filter of much lower order. / Ett av områdena inom telekommunikation som har ökat mest de senaste åren är radio kommunikation. Det finns många olika varianter av trådlösa radio system, men de har alla en sak gemensamt, de överför information/data via ett radiogränssnitt. Signaler som sänds över en radiokanal kommer på grund av många olika anledningar att bli störda eller distorderade. I Jörgen Nordbergs doktorsavhandling ?Signal Enhancement in Wireless Communication Systems? presenteras flera metoder för att förbättra kvaliten i de mottagna signalerna vilket ger betydande kvalitetsförbättring. Huvuddelen av denna doktorsavhandling behandlar interferensundertrycking, d.v.s. hur man undertrycker oönskad störning på den egna radiokanalen. Dessa metoder är baserade på användning av flera antenner i mottagaren. Genom att ta emot signalerna med flera antenner så kan metoder såsom diversitetskombinering, adaptiva antenner, lobformning, signal separation användas för att förbättra kvaliteten i den mottagna signalen. Om mottagaren har en antenn så behövs oftast kanalutjämning för att förbättra den mottagna signalen och undertrycka intersymbolinterferens. Eftersom kanalutjämning är en typ av inversfiltrering leder detta ofta till estimering av filterparametrar av hög ordning. Estimeringsproblem av hög ordning leder ofta till komplexitetsproblem och konvergensproblem hos estimerings algoritmen. För att motverka dessa problem så presenteras i denna avhandling en kanalutjämnare som är baserad på subbandsteknik. I denna kanalutjämnare så delas den mottagna signalen upp i flera frekvensband (subband) som decimeras till en takt som motsvarar subbandets bandbredd varefter filterparametrarna estimeras i denna lägre takt. Därvid har estimeringsproblemet delats upp i flera små problem som kan hanteras enklare.

Cell biophysical properties are a new class of biomarkers that can characterize cells into subgroups that indicate differences in phenotypes that may correlate with disease and cell state. Microfluidic biophysical cell sorters are platforms that utilize these newly developed biomarkers to expand biomedical capabilities for improvements in cell state detection and characterization. Cell biophysical properties are important indicators for cell state and function because they point to differences in cell structures, such as cytoskeletal arrangement and nuclear content. In particular, some diseases, such as cancer and malaria, can cause significant changes in cell biophysical properties. Therefore, cell biophysical properties have the potential to be used for disease diagnostics. Microfluidic systems which can interrogate these biophysical properties and exploit changes in biophysical properties to separate cells into subpopulations will provide important biomedical capabilities. In this combined theoretical and experimental investigation, we explore a new type of cell sorter which utilizes differences in biophysical properties of cells. These biophysical properties that can be utilized to sort cells include size, elasticity and viscosity. We invented a microfluidic system for continuous, label-free cell separation that utilizes variations in cell biophysical properties. A microfluidic channel is decorated by periodic diagonal ridges that are designed to compress flowing cells in rapid succession. The physical compression, in combination with hydrodynamic secondary flows induced by the ridged microfluidic channel, translates each cell perpendicular to the channel axis in proportion to its biophysical properties. Through careful experimental and computational studies, we found that the cell trajectories in the microfluidic cell sorter correlated to these biophysical properties. Furthermore, we examine the effect of channel design parameters under various experimental conditions to derive cell separation models that can be used to qualitatively predict cell sorting outcome. A variety of biophysical measurement tools, including atomic force microscopy and high-speed optical microscopy are used to directly characterize the heterogeneous population of cells before and after separation. Taken together, we describe the physical principles that our microfluidic approach can be effectively used to separate a variety of cell types. The major contribution is the creation and characterization of a novel microfluidic cell- sorting platform that utilizes cell biophysical properties to enrich cells into phenotypic subtypes. This innovative approach opens new ways for conducting rapid and low-cost cell analysis and disease diagnostics through biophysical markers.

Thesis (MA)--University of Stellenbosch, 2001. / ENGLISH ABSTRACT: Suicide is currently one of the leading causes of death in many countries, and is still stigmatized to some extent in some cultures. As bereavement by suicide is a very difficult loss to adjust to, this study aims at creating a better understanding of the adjustment process that survivors of suicide have to go through. The study focuses on the impact of this kind of bereavement on family members and other people touched by the loss of someone to suicide. The needs of the bereaved have to be researched so that a suitable intervention programme can be developed to lessen the severity of the aftermath for survivors of suicide. Supportive aftercare (postvention) may also help prevent further tragedies following in the wake of suicide. The severity and stigma of suicide often contribute to the isolation of nuclear family members in their grief at a time when societal support would have been most helpful. Suicide touches the lives of people of all ages. Some may have special needs such as parents who lose a child to suicide or children whose parent has committed suicide. Better knowledge and understanding of the experiences of these survivors may guide caregivers to assist them with their bereavement and adjustment process as well as assist them in acquiring the necessary coping skills to work through the guilt, fears, anger, regrets and sorrow associated with their tragic loss. A review of the relevant literature is presented with pertinent hypotheses to inform further research to develop a suitable intervention programme for survivors of suicide in the nuclear family. A questionnaire is also presented that may guide interviewing of people affected by suicide in the family. / AFRIKAANSE OPSOMMING: Selfmoord lS tans een van die leidende oorsake van sterfte in baie lande van die wereld. Die verlies van 'n geliefde aan selfmoord is baie moeilik om te verwerk, en hierdie studie beoog om beter begrip vir hierdie proses te bewerkstellig. Daardeur kan die samelewing meer bewus word van die impak van selfmoord op die naasbestaandes van iemand wat as gevolg van selfrnoord gesterf het. Die spesifieke behoeftes van die treurendes moet nagevors word sodat toepaslike intervensieprograrnme uitgewerk kan word, wat kan bydra om die impak van selfmoord op naasbestaandes to help versag. Ondersteuning aan naasbestaandes na selfmoord kan die voorkoms van verdere tragedies in die gesin help voorkom. Die geweldige impak asook die stigma van selfmoord van 'n gesinslid dra dikwels by tot isolasie van die kemgesin tydens hul routydperk,juis terwyl hulle dit die nodigste het. Selfrnoord raak mense van aile ouderdomme, elk met hul eiesoortige behoeftes, soos ouers wie se kind selfmoord gepleeg het of kinders van wie 'n ouer gesterf het as gevolg van selfmoord. Beter kennis en begrip van die ervarings van naasbestaandes kan hulpverleners lei om bedroefdes te help met hul rouproses en aanpassing, asook hulle bystaan om die nodige hanteringsvaardighede te verwerf sodat hulle die samehangende skuldgevoelens, vrese, woe de, berou en verdriet kan verwerk. 'n Oorsig van die toepaslike literatuur word aangebied met pertinente hipoteses om verdere navorsing toe te lig in die ontwikkeling van 'n toepaslike intervensieprogram vir naasbestaandes na selfmoord in die kemgesin. 'n Vraelys word aangebied wat onderhoudvoering met naasbestaandes kan lei.

Thesis(PhD)--Stellenbosch University, 2008. / ENGLISH ABSTRACT: Aminopolycarboxylic acids (APCAs) are chelating agents widely used to inactivate various metal ions by complex formation in industrial and household applications. Ethylenediaminetetraacetic acid (EDTA) and diethylenetriaminepentaacetic acid (DTPA) are the widely used agents. Their use is under scrutiny due to their persistence in the environment because they cannot readily biodegrade. This led to the introduction of readily biodegradable agents namely ethylenediaminedisuccinic acid (EDDS) and iminodisuccinic acid (IDS) as alternatives especially to EDTA. Therefore, there was an interest to study the separation of EDDS, IDS and other APCAs using a simple, quick and accurate method. Capillary electrophoresis was used to determine the separation and speciation of iminodisuccinic acid with various metal ions at various pH levels. Speciation modelling was also utilized to compare and validate the presence and distribution of metal-ligand species. The obtained CE results were compared with speciation profiles and a reasonable agreement was obtained. The degradation studies at various time intervals for the metal-ligand (ML) complexes of DTPA, S,S-EDDS, IDS and R,S-IDS with various metal ions (Cd2+, Cr3+, Cu2+, Fe3+, Mn2+, Pb2+ and Zn2+) at pH 7 and 9 was evaluated using CE. New peaks were observed in some ML complexes when the pH was changed from pH 9 to 7. Sharp peaks were seen for CuL (L = DTPA, S,S-EDDS, IDS and R,S-IDS), FeDTPA and FeEDDS at both pH s. While small broad peaks were observed for FeIDS, CrL and MnL complexes. CuDTPA and CuEDDS complexes showed a greater stability over some considerable time as compared to CuIDS, CuR,S-IDS and other metal complexes at pH 9. This work also investigated the effect of various cationic electroosmotic flow (EOF) modifiers and counter anions on the CE separation of EDTA, EDDS and IDS as Cu(II) complexes. The performance of the modifiers was evaluated in terms of migration times, resolution and plate numbers. The best results were observed when Tetradecyltrimethylammonium bromide (TTAB) and Cetyltrimethylammonium bromide (CTAB) was used as modifiers in order to reverse the EOF in the fused silica capillary. This resulted in short analysis time and better peak shapes. The effect of different counteranions attached to EOF modifiers on the separation was also shown. It was also found that the counter anions of EOF modifiers used influences the separation of the complexes. The EOF modifiers namely Cetyltrimethylammonium chloride (CTAC) and Tetradecyltrimethylammonium chloride (TTAC) were further utilized for the determination of EDTA in South African river waters and industrial effluents. A method for the simultaneous separation of Fe (III) complexed with EDTA, S,S -EDDS and IDS was developed by CE and high-performance liquid chromatography (HPLC). The recalcitrant EDTA is used in combination with readily biodegradable analogues like EDDS and IDS in many commercial products. The methodology performance was evaluated in terms of linearity, limit of detection (LOD), limit of quantitation (LOQ) and reproducibility for both CE and HPLC methods. The LOD values obtained from HPLC were low when compared with CE. The applicability of both methods was demonstrated for the analysis of cosmetic products such as foam bath and shower cream. The results obtained by both CE and HPLC were found to be comparable and are in good agreement. / AFRIKAANSE OPSOMMING: Aminopolikarboksiel sure (APCAs) is komplekseer middels wat algemeen gebruik word om verskillende metaal ione te deaktifeer deur kompleks vorming in industriële en huishoudige toepassings. Etileendiamientetraasynsuur (EDTA) en dietileentriamienpentaasyn suur (DTPA) is die mees algemene APCA s. Hul gebruik word deesdae noukerig ondersoek as gevolg van hul volharding in die omgewing. Daar is n intense soektog na bio-afbreekbare agente soos etieleendiamiendisuksien suur (EDDS) and iminodisuksien suur (IDS) wat as plaasvervangers kan dien vir nieafbreekbare EDTA. Daar is dus n behoefte om te kyk na eenvoudige, vinnige en noukeurige metodes vir die bepaling van EDTA, EDTA , IDS en ander APCA s. Kapillere elektroforese (CE) was gebruik vir die skeiding en spesiering van iminodisuksien suur met verskillende metale by verskillende pH s. Spesiasie modellering was ook gebruik om die teenwoordigheid en verspreiding van metaal- spesies te vergelyk. Die CE uitslae was met die spesiasie profiele vergelyk en n redelike ooreenkoms was gevind. Die degraderings studies as n funksie van tyd was met CE bestudeer vir verskillende metal-ligand (ML) samestellings van DTPA, S,S-EDDS, IDS en R,S-IDS met verskillende metal ione (Cd2+, Cr3+, Cu2+, Fe3+, Mn2+, Pb2+ en Zn2+) by pH 7 en 9. Nuwe pieke was opgemerk in sommige ML samestellings wanneer die pH van pH 9 na 7 verander. Hoë pieke was vir CuL (L = DTPA, S,S-EDDS, IDS and R,S-IDS), FeEDTA en FeEDDS by alle pH s gevind. Lae, breë pieke was vir FeIDS, CrL en MnL komplekse gevind. CuDTPA en CuEDDS komplekse het n goeie stabiliteit gewys oor ʼn redelike tyd as dit met CuIDS, CuR,S-IDS en ander metal komplekses by pH 9 vergelyk word. In hierdie werk was die effek van verskillende kationiese elektro-osmotiese stroom (EOF) modifiseerders ook ondersoek. Veral die effek wat teen ioone op die CE skeidings het van EDTA, EDDS en IDS asook Cu(II) komplekse was ondersoek. Die effek van die modifiseerders was ondersoek en ge-evalueer in terme van migrasie tye, resolusie en plaat getalle. Die beste skeidingskondisies was bereik wanneer tetradesieltrimetielammonium bromied (TTAB) and setieltrimetielammonium bromied (CTAB) as modifiseerders gebruik word. Hierdie kondisies het ook aanleiding gegee tot korter ondersoek tye en beter piekvorme. Die effek van verskillende teen ioone wat aan die EOF modifiseerders gekoppel was het ook interresante resultate opgelewer. Die EOF modifiseerders setieltrimetielammonium chloried (CTAC) en tetradesieltrimetielammonium chloried (TTAC) was ook gebruik vir die bepaling van EDTA in Suid Afrikaanse rivier waters en industrieel afloop. ʼn Metode vir die gelyktydige skeiding van Fe(III) met EDTA, S,S’-EDDS en IDS was met behulp van CE en hoedruk vloeistof chromatography (HPLC) ontwikkel. Die metodologie was ondersoek ingevolge lineariteit, limiet van deteksie (LOD), limiet van kwantifisering (LOQ) en die herhaalbaarheid van CE en die HPLC metodes. Die LOD waardes verkry vanaf HPLC was swakker vergeleke met die verkry deur CE. Die toepaslikheid van al die metodes was vir die ontleding van kosmetiese produkte soos bad skuim en stortbad room getoets. Die uitslae deur CE en HPLC was vergelykbaar en ʼn goeie ooreenkoms was gevind.