BEGIN:VCALENDAR VERSION:2.0 PRODID:-//CERN//INDICO//EN BEGIN:VEVENT SUMMARY:Protein localization and folding mechanisms revealed by molecular dynamics simulations DTSTART;VALUE=DATE-TIME:20110714T100000Z DTEND;VALUE=DATE-TIME:20110714T101500Z DTSTAMP;VALUE=DATE-TIME:20261009T005740Z UID:indico-contribution-286-4866@events.saip.org.za DESCRIPTION:Speakers: James Gumbart (Argonne National Laboratory)\nMany na scent proteins\, including nearly all membrane and secreted\nproteins\, mu st traverse a membrane-bound protein-conducting channel prior to their ful l maturation. This channel\, the Sec translocon\, is found in all domains of life and possesses the novel ability to direct nascent proteins to the membrane or to the extracellular space\, depending on their sequences\, o ften concomitant with their synthesis by the ribosome. By combining atomi c structures with cryo-electron microscopy data using the molecular dynami cs flexible fitting method\, we have developed some of the first views of inactive and active translocons in complex with the ribosome. These views reveal a conserved mode of interaction between translocon and ribosome as well as the roles of specific elements of both in protein localization. W e also carried out two-dimensional potential-of-mean-force calculations to explore the structure of the nascent peptide within the translocon enviro nment. The calculations revealed that the translocon exerts a small bias on the peptide towards a helical state. This bias can serve to\nfacilitat e\, e.g.\, the insertion of nascent membrane proteins into the otherwise\n inhospitable lipid bilayer.\n\nhttps://events.saip.org.za/event/7/contribu tions/4866/ LOCATION: Acro3 URL:https://events.saip.org.za/event/7/contributions/4866/ END:VEVENT BEGIN:VEVENT SUMMARY:Comparative Efficiency Study of a Solar Trough Receiver: Hot mirro r and Selective coating DTSTART;VALUE=DATE-TIME:20110713T101500Z DTEND;VALUE=DATE-TIME:20110713T103000Z DTSTAMP;VALUE=DATE-TIME:20261009T005740Z UID:indico-contribution-286-4863@events.saip.org.za DESCRIPTION:Speakers: Marie Chantal CYULINYANA (University of the Witwater srand)\nWe consider a solar trough system in which cylindrical parabolic m irrors focus the sun’s radiation onto a receiver pipe\, heating it. Conv entionally\, the pipe is enclosed in a glass cover under vacuum and the do minant radiation losses are reduced by the use of a selective coating on t he receiver pipe. We study the suitability of applying a ‘hot mirror’ coating on the glass cover instead\, which transmits in the visible but re flects well in the infra-red. We compare the performance of the ‘selecti ve’ with a ‘hot mirror’ coating using the results from simulations f or a general heat transfer model. It is seen that a hot mirror is a viable alternative\, and certainly allows higher temperatures of the working flu id and therefore higher Carnot efficiency. The optimum is a hybrid system\ , with selective coating applied at the low temperature end of the receive r pipe and the hot mirror being used at higher temperatures.\n\nhttps://ev ents.saip.org.za/event/7/contributions/4863/ LOCATION: Acro3 URL:https://events.saip.org.za/event/7/contributions/4863/ END:VEVENT BEGIN:VEVENT SUMMARY:The structure and flexibility of the photosynthetic machinery in p lants and algal cells DTSTART;VALUE=DATE-TIME:20110714T120000Z DTEND;VALUE=DATE-TIME:20110714T123000Z DTSTAMP;VALUE=DATE-TIME:20261009T005740Z UID:indico-contribution-286-4891@events.saip.org.za DESCRIPTION:Speakers: Gyözö Garab (Biological Research Center\, Hung. Ac ad. Sci.)\nIn order to increase the efficiency of light capturing\, all ph otosynthetic organisms capable of oxygen evolution have evolved multilamel lar membrane systems of the thylakoid membranes\, flat closed bilayer lipi d vesicles\, which accommodate the densely packed protein complexes in ord ered\, often semi-crystalline arrays. This highly organized system with su bstantial stability exhibit remarkable structural and functional flexibili ty at different levels of complexity\, which enables these organisms to ca rry out rapid adaptations in response to changes in the environmental cond itions. In this talk\, my attention will be focused on the macro-organizat ion of the protein complexes - and their role in determining the multilame llar membrane ultrastructure\, and will show mechanisms that allow well id entifiable reversible reorganizations in the internal order of the complex es and in the membrane system. \nWe have shown that the main chlorophyll a /b light harvesting complexes of photosystem II (LHCII) form chirally orga nized macrodomains both in vivo and in vitro. These macrodomains\, togethe r with stacking\, play important roles in the lateral segregation (sorting ) of the two photosystems between the granum and stroma membranes\, and th us in the assembly and stabilization of the membrane ultrastructure [Must árdy and Garab\, 2003\, TIPS 8: 117]\, which has been determined by elect ron tomography [Mustárdy et al.\, 2008\, Plant Cell 20: 2552]. The macrod omains also possess a remarkable structural flexibility\, being capable of undergoing light-induced reversible reorganizations\, that are largely in dependent of the photochemical activity of thylakoids\, and are approximat ely linearly proportional to the light intensity above the saturation of p hotosynthesis – an important\, unique feature with respect to protection of plants against excess excitation [Barzda et al.\, 1996\, Biochemistry 35: 8981]. This type of reorganizations include (i) unstacking of membrane s\, (ii) a lateral desorganization of the macrodomains\, and (iii) monomer ization of the LHCII trimers [Dobrikova et al.\, 2003\, Biochemistry 42: 1 12726]. Isolated\, lipid-enriched\, loosely stacked lamellar aggregates of LHCII also possess the ability to undergo similar reorganizations\, accom panied by fluorescence quenching transients. These structural transitions are accounted for by a biological thermo-optic mechanism: fast thermal tra nsients\, arising from dissipated excitation energy\, which can lead to el ementary structural transitions in the close vicinity of the site of dissi pation due to the presence of ‘built-in’ thermal structure-instabiliti es [Cseh et al.\, 2005\, Photosynth Res 86: 263]. They lend local structur al flexibility to molecular (macro)assemblies of high stability\, and appe ar to be involved in important enzymatic reactions\, as revealed in other laboratories [Zer et al.\, 1999\, PNAS 96: 8277\, Yang et al.\, 2000\, FEB S Lett 466: 385]. The lipid content of the membranes is self regulated by non-bilayer lipids\, via their segregation capability. By this means they safe-guard the high protein content of the thylakoid membranes and\, at th e same time\, they contribute to the structural flexibility of the membran e system [Garab et al.\, 2000 Trends Plant Sci. 5:489\; Krumova et al.\, 2 008\, Biochim. Biophys. Acta\, Biomembranes 1778: 997].\nIn order to chara cterize the multilamellar membrane system\, we determined characteristic r epeat distances of the photosynthetic membranes in living cyanobacterial a nd eukaryotic algal cells and in intact thylakoid membranes isolated from higher plants with time-resolved small-angle neutron scattering (SANS). It has been shown how the different organization of multilamellar membrane s ystem can be correlated with different compositions and protein macro-orga nizations in different organisms. SANS also revealed small (~10 Å) but we ll identifiable light-induced reversible changes in these organisms\, obse rved for the first time in living cyanobacteria and diatom cells. These re organizations\, which could be recorded with time resolutions of several s econds and minutes\, appear to be associated with functional changes in vi vo [Nagy et al.\, 2011\, Biochem J. 436: 225].\n\nhttps://events.saip.org. za/event/7/contributions/4891/ LOCATION: Acro3 URL:https://events.saip.org.za/event/7/contributions/4891/ END:VEVENT BEGIN:VEVENT SUMMARY:Laser Irradiation: A Complementary Treatment for Wounds? DTSTART;VALUE=DATE-TIME:20110714T094500Z DTEND;VALUE=DATE-TIME:20110714T100000Z DTSTAMP;VALUE=DATE-TIME:20261009T005740Z UID:indico-contribution-286-4899@events.saip.org.za DESCRIPTION:Speakers: Nicolette Houreld (Laser Research Centre\, Universit y of Johannesburg)\nSince the invention of the laser\, its application in the health sector has been studied and in an attempt to discover effective alternative treatments\, Low Level Laser Therapy (LLLT)\, commonly known as biostimulation or photo-biostimulation\, has emerged. This therapy has been successfully used both in in vitro and in vivo studies in wound heali ng. Although this therapy is in use worldwide\, the full mechanisms of act ion are not fully understood. Various cell culture models\, such as wounde d\, diabetic wounded and hypoxic\, have been exposed to visible and infra- red laser light and the effect on cell migration\, cell survival\, prolife ration\, cytotoxicity\, mitochondrial responses\, nitric oxide\, secondary messengers\, DNA damage and pro-inflammatory cytokines have been studied. Laser irradiation at the correct wavelength and fluence has shown to have a positive effect on stressed cells in vitro. There is an increase in mig ration\, survival and proliferation\, mitochondrial activity\, nitric oxid e and secondary messengers. A decrease in cytotoxicity\, DNA damage and pr o-inflammatory cytokines is also seen. LLLT offers an alternative wound he aling therapy. At a biochemical level there is a positive effect on cells\ , with stressed cells being pushed into cell survival pathways.\n\nhttps:/ /events.saip.org.za/event/7/contributions/4899/ LOCATION: Acro3 URL:https://events.saip.org.za/event/7/contributions/4899/ END:VEVENT BEGIN:VEVENT SUMMARY:Determining optical performance and current generation of a CPV d ue to intensity distribution DTSTART;VALUE=DATE-TIME:20110713T090000Z DTEND;VALUE=DATE-TIME:20110713T091500Z DTSTAMP;VALUE=DATE-TIME:20261009T005740Z UID:indico-contribution-286-4905@events.saip.org.za DESCRIPTION:Speakers: Ross Schultz (Nelson Mandela Metropolitian Universit y)\nHigh concentration photovoltaic (CPV) systems utilize non-imaging opti cs to concentrate and distribute the solar flux uniformly onto a solar rec eiver to achieve maximum performance and power output from a CPV module. H owever\, in many cases due to mechanical misalignment\, tracker error and imperfections in the optical material\, the optimum performance of the mod ule is compromised.\nA LabVIEW programme employing visualization was used to determine the main contributing factor for current generation\, i.e. po sition and intensity of the distribution. The topography was determined by multiple roster scans with a spectroradiometer and optical fiber in the p lane of the reflective secondary’s aperture where the cell would be plac ed. The results showed different currents been generated at different poin ts on the cell surface. These results were put into a CPV cell current-vol tage (I-V) characteristic simulator to extract I-V curve at each point. Th ese were then compared with measured I-V curves obtained from the CPV syst em. The results showed that there was a non-uniform current densities (Jsc ) distribution due to non-uniform spectral and intensity distribution acro ss the cell surface.\n\nhttps://events.saip.org.za/event/7/contributions/4 905/ LOCATION: Acro3 URL:https://events.saip.org.za/event/7/contributions/4905/ END:VEVENT BEGIN:VEVENT SUMMARY:Indoor temperature predictions in an energy efficient solar house DTSTART;VALUE=DATE-TIME:20110713T120000Z DTEND;VALUE=DATE-TIME:20110713T121500Z DTSTAMP;VALUE=DATE-TIME:20261009T005740Z UID:indico-contribution-286-4931@events.saip.org.za DESCRIPTION:Speakers: Sosten Ziuku (Fort Hare Institute of Technology)\nTh is paper presents results of long term temperature monitoring in an energy efficient solar house at the University of Fort Hare\, South Africa. Meas ured data was stored by a datalogger every 10 minutes. Formulas for predic ting the daily indoor maximum\, average and minimum temperatures were deve loped on the basis of outdoor climatic parameters. Passive solar housing a ims to raise and lower indoor temperatures in winter and summer respective ly. As a result\, analysis of the data and development of predictive formu las of indoor temperature were done separately on part of the winter and s ummer seasons. The models were then validated against measurements taken i n different time periods. Results indicated that indoor maximum\, average and minimum temperatures can be predicted on the basis of outdoor temperat ure. Prediction of maximum indoor temperature was improved by incorporatin g daily solar irradiance in the formula. It was also revealed that indoor temperatures are affected by outdoor temperatures of the previous two day s. The different ways at which the house is cooling and heating were also investigated.\n\nhttps://events.saip.org.za/event/7/contributions/4931/ LOCATION: Acro3 URL:https://events.saip.org.za/event/7/contributions/4931/ END:VEVENT BEGIN:VEVENT SUMMARY:Application of Electroluminescence and Thermal Imaging in Defect I dentification in Photovoltaic Modules DTSTART;VALUE=DATE-TIME:20110713T100000Z DTEND;VALUE=DATE-TIME:20110713T101500Z DTSTAMP;VALUE=DATE-TIME:20261009T005740Z UID:indico-contribution-286-4951@events.saip.org.za DESCRIPTION:Speakers: Jacqui Crozier (NMMU)\nIn order for solar energy to become an alternative to traditional fossil fuel energy it is important th at defects in photovoltaic (PV) modules can be easily identified. Typicall y a module is characterised by measuring the current-voltage (I-V) charact eristics under standard test conditions. In addition to this electrolumine scence (EL) and thermal imaging can be used to identify the location of de fects in the module. A cooled Si CCD camera is used to detect the EL emitt ed from a forward biased PV module. The intensity of this light is related to the minority carrier concentration and the emitted EL thus provides a visual representation of defects in the cell. Infrared imaging can be used to identify irregular heating patterns which are indicative of defective cells or contacts. In this study we used both techniques in conjunction to assess the defects present in a 36 cell custom-made single crystalline si licon module. Defects that were identified in this study showed that areas around the contacts appeared very bright in EL images and this correspon ded with hot areas in the infrared images. These results show that the ele ctrical contacts in these areas are poor.\n\nhttps://events.saip.org.za/ev ent/7/contributions/4951/ LOCATION: Acro3 URL:https://events.saip.org.za/event/7/contributions/4951/ END:VEVENT BEGIN:VEVENT SUMMARY:Inflammatory response of injured diabetic fibroblasts after low in tensity laser irradiation at a wavelength of 830 nm DTSTART;VALUE=DATE-TIME:20110714T091500Z DTEND;VALUE=DATE-TIME:20110714T093000Z DTSTAMP;VALUE=DATE-TIME:20261009T005740Z UID:indico-contribution-286-4964@events.saip.org.za DESCRIPTION:Speakers: Palesa Sekhejane (DTech Student)\nDiabetes mellitus (DM) is a chronic disease characterized by impeded glucose metabolism and preceded by diabetic ulcers which are chronic due to deteriorated healing process. Hypoxia\, decreased fibroblast proliferation and impaired growth factors are amongst root factors that contribute to impaired healing. Phot ostimulation is a non-invasive treatment that utilizes low intensity laser irradiation (LILI) to provide healing or stimulate appropriate cellular f unctions. Human skin fibroblast cells (WS1) were used in this study that c onsisted of four groups viz. normal\, normal wounded\, diabetic wounded an d hypoxic\, each with a non-irradiated control. Wounding was simulated by creating a central scratch using a pipette. A diabetic state was induced b y growing cells in media that contained excess glucose to a final concentr ation of 22.56 mM\, and for hypoxic insult cells were incubated under anae robic conditions (0% O2 and 20% CO2) for 4 h. Cells were then irradiated a t a wavelength of 830 nm with 5 J/cm2 and incubated for 1 or 24 h. Morphol ogical changes were observed by light microscopy\; ELISA and flow cytometr y were used to determine interleukin (IL)-1β\, IL-6 and tumour necrosis f actor (TNF)-α as inflammatory markers\; and caspase 3/7 for apoptosis was determined by luminescence. After a 24 h incubation period the wounded ar ea appeared decreased and hypoxic cells had regained normal morphologic fe atures when irradiated\, TNF-α and IL-1β had decreased in irradiated sam ples\, whereas IL-6 was increased. Caspase 3/7 had decreased in irradiated samples at both 1 and 24 h. This study demonstrated the beneficial effect s of LILI since the results showed significantly reduced inflammatory resp onse in vitro and hastened wound healing particularly under diabetic and h ypoxic conditions.\n\nhttps://events.saip.org.za/event/7/contributions/496 4/ LOCATION: Acro3 URL:https://events.saip.org.za/event/7/contributions/4964/ END:VEVENT BEGIN:VEVENT SUMMARY:Construction and thermal analysis of a parabolic collector for sma ll scale concentrating thermal system DTSTART;VALUE=DATE-TIME:20110713T121500Z DTEND;VALUE=DATE-TIME:20110713T123000Z DTSTAMP;VALUE=DATE-TIME:20261009T005740Z UID:indico-contribution-286-5002@events.saip.org.za DESCRIPTION:Speakers: Tomas Nhabetse (Eduardo Mondlane University\, Maputo \, Mozambique)\n\nFew options are apparent for achieving a benign\, sustai nable energy future except those relying on the utilization of solar energ y in one way or another. Experience with fossil and nuclear sources has re vealed an array of unsolved problems of increasing concern as more evidenc e and understanding emerges. Africa has the world’s best solar resources . Several countries have exploited solar energy for water heating\, crop d rying\, medical applications\, and telecommunications\, among other things . Solar energy can contribute to supply heat energy in households of Sub-S aharan African countries. Having this in mind a small scale dish concentra ting solar energy system is being developed at the Eduardo Mondlane Univer sity in Mozambique. The system comprises of the collector\, the heat stora ge and the oven. The main structure of the system has been constructed\, c onsisting of the dish reflector\, the sun tracker and the piping mechanism . The reflector consists of 6 petals which together resemble nearly a para bolic surface with the following parameters: \nDiameter................ Dp = 2400mm\nFocal length............ f = 915mm\nF/D ratio............ ......... n=0.135\nHalf opening angle..............66.50o \nHalf comp lementary angle........23.49o\nAngle of incidence..............33.26 \ n\nThe process of gluing trapezoidal mirrors was done on individual petals using the laser beam radiation. Using reflection laws on planar surfaces which states that rays of light parallel to the parabola axis are reflecte d to a focal point\, each trapezoidal mirror tile gluing was preceded by s canning its reflection close to the theoretical focal point. An individual petal was covered by 163 mirror tiles. The reflector surface is comprised by 978 mirror tiles.\nAn infrared camera was used to scan the temperature of the concentrated heat. The maximum temperature reached so far is 350oC . The experimental focal area was found by mapping the reflections of the whole reflective surface. The shape of the receiver/absorber obtained by t he scanning process is semi-spherical. \nThe future work is the study of e fficiency of the collector as a whole. This will be done by measuring the ambient air temperature\, the inlet and outlet temperature of the absorber .\n\nhttps://events.saip.org.za/event/7/contributions/5002/ LOCATION: Acro3 URL:https://events.saip.org.za/event/7/contributions/5002/ END:VEVENT BEGIN:VEVENT SUMMARY:Nuclear and related analytical techniques for biotechnology DTSTART;VALUE=DATE-TIME:20110714T101500Z DTEND;VALUE=DATE-TIME:20110714T103000Z DTSTAMP;VALUE=DATE-TIME:20261009T005740Z UID:indico-contribution-286-5008@events.saip.org.za DESCRIPTION:Speakers: Marina Frontasyeva (Joint Institute for Nuclear Rese arch)\nSome results from applying nuclear and related analytical technique s in medical\, environmental and industrial biotechnologies are presented. In the biomedical experiments biomass from the blue-green alga Spirulina platensis has been used as a matrix for the development of pharmaceutical substances containing such essential trace elements as selenium\, chromium and iodine. The feasibility of target-oriented introduction of these elem ents into Spirulina platensis biocomplexes retaining its protein compositi on and natural beneficial properties was shown. The negative influence of mercury on growth dynamics of Spirulina platensis was observed. Detoxifica tion of Cr and Hg by Arthrobacter globiformis 151B was demonstrated. Micro bial synthesis of technologically important silver nanoparticles by the no vel actinomycete strain Streptomyces glaucus 71 MD was characterized by a combined use of Transmission Electron Microscopy (TEM) and ENAA. It was es tablished that the tested actinomycete Streptomyces glaucus 71 MD produces silver nanoparticles extracellularly when acted upon by the silver nitrat e solution\, which offers a great advantage over an intracellular process of synthesis from the point of view of applications. The synthesis of silv er nanoparticles by Spirulina platensis proceeded differently under the sh ort-term and long-term silver action. Our studies will help to develop a r ational microbial nanoparticle synthesis procedure.\n\nhttps://events.saip .org.za/event/7/contributions/5008/ LOCATION: Acro3 URL:https://events.saip.org.za/event/7/contributions/5008/ END:VEVENT BEGIN:VEVENT SUMMARY:Identification of compounds in materials using tomography imaging\ , a possibility at the SANRAD facility DTSTART;VALUE=DATE-TIME:20110715T061500Z DTEND;VALUE=DATE-TIME:20110715T063000Z DTSTAMP;VALUE=DATE-TIME:20261009T005740Z UID:indico-contribution-286-5018@events.saip.org.za DESCRIPTION:Speakers: Robert Nshimirimana (NECSA)\nThe South African Neutr on Radiography (SANRAD) facility hosts a neutron/x-ray tomography system w hich is extensively being utilized in non-destructive examination experime nts where it is necessary to characterize and determine the properties (e. g. size\, porosity\, permeability and morphology) of samples. Sometimes\, quantitative information is needed about the type elemental composition of the sample or the constituencies of the sample\, in a non-destructive man ner. Different compounds within the sample interact differently with a neu tron/x-ray source\, hence it is possible not only to reveal the internal s tructure of the material but also to identify the compound within the mate rial. This talk demonstrates first research results obtained at the SANRAD facility for the calibration and quantifying of compounds\, or minerals\, within geological samples by means of transmission radiography and tomogr aphy.\n\nhttps://events.saip.org.za/event/7/contributions/5018/ LOCATION: Acro3 URL:https://events.saip.org.za/event/7/contributions/5018/ END:VEVENT BEGIN:VEVENT SUMMARY:Ionizing Radiation as Imaging Tool in Coal Characetrization and Ga sification Research DTSTART;VALUE=DATE-TIME:20110715T064500Z DTEND;VALUE=DATE-TIME:20110715T070000Z DTSTAMP;VALUE=DATE-TIME:20261009T005740Z UID:indico-contribution-286-5035@events.saip.org.za DESCRIPTION:Speakers: Jakobus Hoffman (Necsa)\nAround 70 million tones of coal are burned annually in power stations whilst around 50 million tones of coal are converted to chemicals in the petrochemical sector in the same period of time. Researchers\, nationally and internationally\, aim to op timize the processes to extract the most energy from the limited coal rese rves. One such petrochemical process that is of significance to South Afr ica is gasification\, since many industrially important chemicals and fuel s are produced through the gasification process of coal. \nThe process of gasification is influenced by many factors including temperature\, pressu re\, coal composition\, coal size\, etc. and an understanding of each of t hese factors is crucial to optimize and manage a gasifier. The primary wa ys in which information is obtained on these factors are usually destructi ve experimental methods that are applied to powders and small particles. Powders and very small particles are not representative of the mined coal since it usually represents either average or homogeneous coal structures. \nIt is therefore beneficial to conduct research on coal in order to stu dy the coal structure and processes to beneficiate coal in a non-destructi ve fashion. One such technique is micro-focus X-ray Computed Tomography (C T) which enables the researcher to visualize and quantify the coal composi tion and spatial distribution of constituents and voids (cleats and fractu res). Armed with this knowledge the scientist can investigate and optimiz e conversion processes such as gasification as well as other physical proc ess (methane extraction and carbon dioxide adsorption). \nThis presentati on deals with the characterization of coal and the investigating of the fi rst stages of gasification in a non-destructive manner. Coal particles wi th two distinct coal macerals (organic components) were investigated and t he information obtained was compared to data from a thermo gravimetric ana lyzer (TGA). The main objective of this study was therefore to obtain a b etter understanding of gasification through a non-destructive analytical t echnique.\n\nhttps://events.saip.org.za/event/7/contributions/5035/ LOCATION: Acro3 URL:https://events.saip.org.za/event/7/contributions/5035/ END:VEVENT BEGIN:VEVENT SUMMARY:Characterization of the Phase Transition of h-BN - c-BN Nanopartic les by Ion Implantation DTSTART;VALUE=DATE-TIME:20110715T101500Z DTEND;VALUE=DATE-TIME:20110715T103000Z DTSTAMP;VALUE=DATE-TIME:20261009T005740Z UID:indico-contribution-286-5069@events.saip.org.za DESCRIPTION:Speakers: Emily Aradi (University of the Witwatersrand)\nThe s ynthesis of the c-BN (cubic boron nitride) has developed great interest du e to its excellent physico-electrochemical properties. These include\; hi gh hardness values (73 GPa) second after diamond\, wide band gap (6.4 eV)\ , optical transparency in a wide region of the electromagnetic spectrum\, high temperature stability (1200 oC) and chemical inertness. These propert ies enable c-BN to be very useful for various industrial and electrical ap plications such as in cutting and grinding\, fabrication of high temperatu re high frequency devices among many others.\nIn this work\, ion irradiati on effect of the soft graphitic boron nitride (h-BN) is investigated from characterization with Raman Spectroscopy before and after implantation. Th is was to investigate a possible phase transformation of h-BN to c-BN. Bor on\, lithium and helium ions were implanted into the hot pressed h-BN samp les at 150keV\, and with fluences ranging from 1x1014 ions/cm2 to 1x1016 ions/cm2. \nRaman Spectroscopy showed that implantation of all the three ions led to an h-BN to a possible c-BN phase transition\, evident from the longitudinal optical (LO) Raman phonon features occurring at 1303cm-1 in the implanted samples’ spectra. The nature of the phonon peaks and their downshifting is explained using the spatial phonon correlation model. The extent of these peaks was found to depend on the mass of the incident ion and the fluence\, where high ion mass required low fluence compared with the low ion masses.\n\nhttps://events.saip.org.za/event/7/contributions/50 69/ LOCATION: Acro3 URL:https://events.saip.org.za/event/7/contributions/5069/ END:VEVENT BEGIN:VEVENT SUMMARY:The Unique Capabilities of Radiation Beam Lines at Necsa as Probes DTSTART;VALUE=DATE-TIME:20110715T070000Z DTEND;VALUE=DATE-TIME:20110715T073000Z DTSTAMP;VALUE=DATE-TIME:20261009T005740Z UID:indico-contribution-286-5074@events.saip.org.za DESCRIPTION:Speakers: Frikkie De Beer (Necsa)\nThe concept of radiation\, in the scientific and analytical environment is normally not understood an d has being neglected and not considered as analytical probe due to the la ck of knowledge of the general public and researchers about its potential as analytical probe\, the misunderstanding of the possible “danger’ in the utilization thereof and the “unavailability” of facilities in Sou th Africa for researchers to utilize.\nGamma-rays\, neutrons and X-ray’s have not any significance for a researcher unless they are controlled and directed in beams with considerable intensity. These collimated beams hav e major potential in revealing the “unknown” information normally hidd en within the objects under investigation e.g. nuclear materials\, museum artifacts’\, precious fossils\, concrete\, etc. \nThis paper is an intro duction to the unique properties of neutron- and X-ray radiation beams in general. The capabilities of these beams as analytical probes are discusse d with special attention to the beam line facilities located at Necsa. Th e availability of these beam lines to be utilized by post graduate student s and researchers will be highlighted.\n\nhttps://events.saip.org.za/event /7/contributions/5074/ LOCATION: Acro3 URL:https://events.saip.org.za/event/7/contributions/5074/ END:VEVENT BEGIN:VEVENT SUMMARY:Application of Dual Energy X-ray Radiography/Tomography on Nuclear and Related Materials DTSTART;VALUE=DATE-TIME:20110715T093000Z DTEND;VALUE=DATE-TIME:20110715T094500Z DTSTAMP;VALUE=DATE-TIME:20261009T005740Z UID:indico-contribution-286-5080@events.saip.org.za DESCRIPTION:Speakers: Takalani Ndanduleni (University of Johannesburg)\nTh is study investigates the principle and capabilities of Dual Energy X-Ray Radiography/Tomography when applied on nuclear and related materials. The dual-energy X-ray technique is a significant improvement to X-ray imaging systems and gives additional information on the composition of the object being imaged. Within this technique\, two radiographs are obtained at two distinct X-ray energies and are combined (divided\, subtracted) to give de tailed information about the material features with improvement of the ima ge contrast. \nX-rays for this research\, will be generated with a new 225 kV microfocus X-ray system to be commissioned by June 2011 at the Nuclear Energy Cooperation of South Africa (Necsa). This system will be able to g enerate different peak energy X-rays at different anode target materials a t very small focal spot sizes in order to obtain high-resolution images. Different X-ray filters will be utilized to shape the energy of the X-ray beam for high energy X-rays to interact with the material.\nThis presentat ion focuses on the principles of X-ray generation with different anode mat erials and the utilization thereof in radiographs and tomograms.\n\nhttps: //events.saip.org.za/event/7/contributions/5080/ LOCATION: Acro3 URL:https://events.saip.org.za/event/7/contributions/5080/ END:VEVENT BEGIN:VEVENT SUMMARY:Monitoring a grid-assist photovoltaic system DTSTART;VALUE=DATE-TIME:20110713T094500Z DTEND;VALUE=DATE-TIME:20110713T100000Z DTSTAMP;VALUE=DATE-TIME:20261009T005740Z UID:indico-contribution-286-5083@events.saip.org.za DESCRIPTION:Speakers: Warren Alistoun (NMMU)\nRecent developments in elect ricity regulatory environment and the possible inclusion of small\, kW-sca le\, photovoltaic (PV) systems in the feed-in tariff framework has led to an increased interest in these systems. In South Africa\, grid reliabilit y issues are not fully mitigated by employing a straight grid-tie PV syste m\, with users sometimes wanting some battery backup for load-shed periods at night. In this study a system comprising a PV array\, maximum power p oint tracker\, a battery bank and inverter was monitored using a custom-bu ild data acquisition system. The monitored parameters include\; environme ntal conditions\, DC and AC power\, and energy flow within the system. Th is paper will discuss the influence of environmental parameters and load r equirements on the performance of the system. Issues such as soiling and other loss mechanisms are also discussed.\n\nhttps://events.saip.org.za/ev ent/7/contributions/5083/ LOCATION: Acro3 URL:https://events.saip.org.za/event/7/contributions/5083/ END:VEVENT BEGIN:VEVENT SUMMARY:X-ray crystallographic studies and quantum mechanical modeling of the amidase reaction mechanism DTSTART;VALUE=DATE-TIME:20110714T114500Z DTEND;VALUE=DATE-TIME:20110714T120000Z DTSTAMP;VALUE=DATE-TIME:20261009T005740Z UID:indico-contribution-286-5111@events.saip.org.za DESCRIPTION:Speakers: Bryan Trevor Sewell (University of Cape Town)\nThe a midases catalyse the conversion of amides to the corresponding carboxylic acid and ammonia. We have visualized the structure of the amidase (MW= 30 kDa) from a bacterium\, Nesterenkonia sp. at atomic resolution by X-ray c rystallography. The primary components of the active site are two negative ly charged carboxylates (E1 and E2) arising from two conserved glutamate s ide chains\, a positively charged amino group (K) arising from a conserved lysine\, a sulphydryl arising from a conserved cysteine and a water molec ule. Mutation of the active site residues has enabled us to visualize the unreacted substrate and a number of artificial intermediate states which h ave led to our insights. We propose a reaction mechanism which passes thro ugh a thioester adduct to the cysteine. Although this in itself is not co ntroversial\, our studies demonstrate for the first time how exquisitely a ccurate geometrical placement of the various groups leads to accurate ster eoelectronic alignment which allows the transition states to form. The con figuration of E1\, E2 and K ensures that K remains positively charged thro ughout the reaction thus enabling it to act as an acid catalyst and provid e an oxyanion hole to stabilize the tetrahedral transition states. The con figuration also accurately positions the substrate for nucleophilic attack by the sulphydryl by hydrogen bonding to the amide\, positions E1 as a b ase catalyst and positions the water with the correct stereoelectronic ali gnment for a nucleophilic attack on the thioester. The transition state en ergies\, electron densities and hydrogen placements calculated using Gauss ian09 demonstrate the plausibility of our proposal.\n\nhttps://events.saip .org.za/event/7/contributions/5111/ LOCATION: Acro3 URL:https://events.saip.org.za/event/7/contributions/5111/ END:VEVENT BEGIN:VEVENT SUMMARY:Three-dimensional electron microscopy and molecular modelling stud ies of a spiral-forming biocatalyst DTSTART;VALUE=DATE-TIME:20110714T103000Z DTEND;VALUE=DATE-TIME:20110714T104500Z DTSTAMP;VALUE=DATE-TIME:20261009T005740Z UID:indico-contribution-286-5112@events.saip.org.za DESCRIPTION:Speakers: Jean Watermeyer (University of Cape Town)\nNitrilase and amidase enzymes catalyse the conversion of nitriles and amides to the ir corresponding acid and ammonia - chemistry which is useful in synthesis of drug compounds and fine chemicals. The conversion of cyanide\, a nitr ile\, to ammonia and formic acid is useful in detoxification of contaminat ed wastewater. The cyanide dihydratase from Bacillus pumilus (CynDpum) ca talyses this reaction and is thus a potentially useful biocatalyst. CynDp um and related nitrilase enzymes become activated by formation of spiral-s haped multimers. Evidence suggests that multimer formation regulates acti vity\, by mechanisms which are still not clear. We have used a combinatio n of transmission electron microscopy (EM) with 3-D image reconstruction\, molecular modelling\, and mutagenesis to investigate the mechanism of hel ix formation in CynDpum. We have implemented a new routine in the molecul ar dynamics package\, NAMD\, that allows helical symmetry to be used as a constraint\, together with the EM volume. This method improves on asymmet rical modelling procedures and has aided in our atomic-level interpretatio n of low-resolution 3-D maps from negative-stain EM. This in turn has all owed us to make testable predictions about the importance of specific amin o acids for the mechanical stability of the spirals. We show that salt br idges in one interface are not required for complex formation\, but that m utations in this area can enhance the mechanical stability of the enzyme.\ n\nhttps://events.saip.org.za/event/7/contributions/5112/ LOCATION: Acro3 URL:https://events.saip.org.za/event/7/contributions/5112/ END:VEVENT BEGIN:VEVENT SUMMARY:A synthetic diamond probe for both low-energy mammography X-rays a nd high-energy electron therapy beams DTSTART;VALUE=DATE-TIME:20110715T090000Z DTEND;VALUE=DATE-TIME:20110715T091500Z DTSTAMP;VALUE=DATE-TIME:20261009T005740Z UID:indico-contribution-286-5149@events.saip.org.za DESCRIPTION:Speakers: Nicholas Ade (None)\nAlthough diamond has been studi ed for dosimetry principally due to its near tissue-equivalence\, its use in both low-energy X-rays and high-energy electron beams has not been repo rted. This report is based on dosimetric studies of a synthetic diamond pr obe when subjected to diagnostic mammography X-ray photons and megavoltage electron therapy beams. The probe\, constructed using entirely tissue-equ ivalent Perspex body was configured for radiation dose measurement in eith er ‘edge-on’ or ‘flat-on’ exposure geometry without having first\, to re-orientate the diamond within the body of the detector\, and it was designed to be compatible with commercial electrometer systems. The radiat ion response of the diamond tested showed negligible energy dependence\; i ts minimal background signal\, high sensitivity (547.52 nC Gy-1mm-3) and s uitability for measurements in small radiation fields of steep dose gradie nts due to its small size make it suitable for clinical dosimetry. The pre sented probe has the potential advantage of replacing conventional radiati on dosimeters.\n\nhttps://events.saip.org.za/event/7/contributions/5149/ LOCATION: Acro3 URL:https://events.saip.org.za/event/7/contributions/5149/ END:VEVENT BEGIN:VEVENT SUMMARY:Optical design of low concentration photovoltaic modules DTSTART;VALUE=DATE-TIME:20110713T093000Z DTEND;VALUE=DATE-TIME:20110713T094500Z DTSTAMP;VALUE=DATE-TIME:20261009T005740Z UID:indico-contribution-286-5161@events.saip.org.za DESCRIPTION:Speakers: Mario Benecke (Nelson Mandela Metropolitan Universit y)\nThe benefit of concentrating sunlight onto solar cells is that expensi ve solar cell material can be reduced and replaced with relatively inexpen sive optical elements\, which has the potential to reduce the cost of sola r energy.\nIn low concentration photovoltaics (LCPV)\, solar cells are sub jected to higher irradiance levels. The electrical output\, and hence effi ciency of a LCPV module is dependent on the amount of irradiance\, tempera ture and more importantly the uniformity of illumination across the solar cells. \nThis paper discusses the design and characterization of the optic al subsystem of a LCPV concentrator. By optimizing the aperture area of th e LCPV concentrator while still maintaining a uniform illumination intensi ty across the solar cells\, the module’s electrical performance can be m aximized. In the study a mathematical model was developed to design and ev aluate suitable optical elements for LCPV application. This model was base d on a facetted reflector that was designed to meet a predetermined set of boundary conditions.\nInitial evaluation of an experimental LCPV concentr ator\, based on this type of design\, will be discussed in this paper. Res ults from the model illustrate the angles and positions of receiver and re flectors for maximum geometric concentration ratio as well as the best ill umination profile across the receiver.\n\nhttps://events.saip.org.za/event /7/contributions/5161/ LOCATION: Acro3 URL:https://events.saip.org.za/event/7/contributions/5161/ END:VEVENT BEGIN:VEVENT SUMMARY:On the Thermal and Electrical Properties of Low Concentrator Photo voltaic (LCPV) Modules DTSTART;VALUE=DATE-TIME:20110713T091500Z DTEND;VALUE=DATE-TIME:20110713T093000Z DTSTAMP;VALUE=DATE-TIME:20261009T005740Z UID:indico-contribution-286-5162@events.saip.org.za DESCRIPTION:Speakers: Jacques Gerber (Nelson Mandela Metropolitan Universi ty)\nEfficient thermal management of low concentrator photovoltaic (LCPV) modules ensures that the maximum power capabilities of the LCPV system are harnessed\, and may substantially prolong the operating lifetime of the p hotovoltaic (PV) cells. A general understanding of the thermal transfer p roperties of PV modules is thus necessary to effectively design\, construc t\, and implement viable LCPV systems. \n\nA basic thermal model based on one-dimensional heat transfer was developed and includes various energy di ssipation mechanisms\, such as convection and radiation. Panel fans were used to simulate air flow across the surface of the PV module and temperat ure measurements of the front and back surface of the PV module were recor ded to analyse energy dissipation in accordance with the basic thermal mod el.\n\nInitial results indicate that 50% of the incoming irradiance is dis sipated through convection and radiation. Optical losses will also be in curred through reflection from the surface of the PV module. The basic th ermal model manages to account for most of the energy incident on a PV mod ule\, and thus effectively illustrates the principle of energy conservatio n within the PV system.\n\nhttps://events.saip.org.za/event/7/contribution s/5162/ LOCATION: Acro3 URL:https://events.saip.org.za/event/7/contributions/5162/ END:VEVENT BEGIN:VEVENT SUMMARY:Miniaturization of electrostatic ion engine through ionization/acc eleration coupling: corona model DTSTART;VALUE=DATE-TIME:20110713T123000Z DTEND;VALUE=DATE-TIME:20110713T124500Z DTSTAMP;VALUE=DATE-TIME:20261009T005740Z UID:indico-contribution-286-5163@events.saip.org.za DESCRIPTION:Speakers: Marius Tchonang Pokaha (Wits University)\nElectrosta tic ion propulsion systems resist miniaturization due to constraints impos ed by the size of the discharge chamber. We introduce a thruster concept w here the same field is responsible for both ionization of the neutrals and acceleration of the ions\, by letting the neutral propellant gas escape i nto a high field region through a thin\, hollow needle at high electric po tential. The ionization mechanism is thus reminiscent of corona ionization . Although the thruster only ionizes a small fraction of the neutral gas\, the ions nevertheless impart a great deal of momentum to the plume\, crea ting an ion wind. We propose a model to estimate the electric behavior of the system\, and two further models for the obtained thrust. A comparison with experimental data shows that the models capture the dominant physical effects and give a reasonable description of the system. Apart from being about a thousand times less massive than conventional systems\, the thrus ter\, which is at the proof-of-concept stage\, performed quite well yieldi ng around 0.3 mN/Watt during initial tests. The thruster small size and si mplicity are advantageous in many situations\, such as for satellite stati on keeping and deep space probes.\n\nhttps://events.saip.org.za/event/7/co ntributions/5163/ LOCATION: Acro3 URL:https://events.saip.org.za/event/7/contributions/5163/ END:VEVENT BEGIN:VEVENT SUMMARY:The effective ionization region and its variation with geometrical and electrical properties of the HVDC transmission system DTSTART;VALUE=DATE-TIME:20110713T130000Z DTEND;VALUE=DATE-TIME:20110713T131500Z DTSTAMP;VALUE=DATE-TIME:20261009T005740Z UID:indico-contribution-286-5172@events.saip.org.za DESCRIPTION:Speakers: Richmore Kaseke (Fort Hare Institute of Technology)\ nHigh Voltage Direct Current (HVDC) overhead power transmission trends are currently advancing toward high system voltages over very long distances in a bid to viably tap from remotely located renewable energy sources. Co rona effect plays a very crucial role in the design of overhead power tran smission systems. Through corona\, part of the energy carried on the tran smission line is expended through ionization and movement of charges in th e air dielectric. Corona limitations influence selection of key line para meters such as diameter of phase conductors\, the number of conductors per phase and conductor clearances to the ground. Since overhead transmissio n lines are installed in open air\, the generated electric fields are non- uniform. As a result\, the accompanying ionization in the surrounding air is non-uniform and does not occur throughout the inter-electrode gap. In stead\, the ionization is confined to a very small region around the high voltage fitting referred to as the Effective Ionization Region (EIR). As such\, corona power loss is proportional to the size of the EIR. This pap er discusses the concept of effective ionization region from a theoretical perspective. Computer modeling was used to investigate the effect of geo metrical as well as electrical line parameters on the size of the EIR. A comparison is made between single and bundled conductor configurations. R esults show that the radius of the EIR of a single conductor that is energ ized at 800 kVDC drops by about 45% if the conductor were a sub-conductor in a four-bundle configuration.\n\nhttps://events.saip.org.za/event/7/cont ributions/5172/ LOCATION: Acro3 URL:https://events.saip.org.za/event/7/contributions/5172/ END:VEVENT BEGIN:VEVENT SUMMARY:Industrial application for Global Quantum Communication DTSTART;VALUE=DATE-TIME:20110713T131500Z DTEND;VALUE=DATE-TIME:20110713T133000Z DTSTAMP;VALUE=DATE-TIME:20261009T005740Z UID:indico-contribution-286-5176@events.saip.org.za DESCRIPTION:Speakers: Abdul Mirza (UKZN)\nIn the last decade the quantum c ommunication community has witnessed great advances in photonic quantum cr yptography technology with the research\, development and commercializatio n of automated Quantum Key Distribution (QKD) devices. These first generat ion devices are however bottle necked by the achievable spacial coverage. This is due to the intrinsic absorption of the quantum particle into the c ommunication line. As QKD is of paramount importance in the future ICT lan dscape\, various innovative solutions have been developed and tested to ex pand the spatial coverage of these networks [R. Alleaume\, 2007\, C. Ellio tt\, 2004\, F. Xu\, 2009] as in the QuantumCity initiative. One such techn ique that is being considered for the creation of a global QKD network is to couple quantum-secured Metropolitan Area Networks(MANs) with secured gr ound-to-satellite links as access points to the global network. This techn ique\, however\, is susceptible to atmospheric parameters and provides ver y limited contact times for the quantum key exchange. \nAs parallel step t o the development of satellite-based QKD networks\, we intend to investiga ting the use of commercial aircrafts as secure transport mechanisms for a global QKD network. Commercial airliners create an ideal alternate global network for key distribution in terms of coverage\, reliability and freque ncy. Further the airports at each connected city have the appropriate supp orting infrastructure to serve as an access point to the global network.\n The quantum-secured global network will provide the infrastructure to crea te\, distribute and manage encryption keys for use in secure global commun ication.\nThe objective of this initial concept to create a proof of conce pt test network to investigate the aforementioned global QKD Network with the use of commercial airliners. The initial systems that are to be used w ill require the aircraft to be a trusted zone although certified tamper-pr oofing techniques will be used. The longterm objective is to upgrade the s ystems to contain quantum security through the use of quantum-powered memo ry solutions.\nA secure key management network layer will also be develope d and implemented to control the flow and usage of keys within the global network. The secure key management network layer will further control the distribution of keys and encryption within the MAN.\n\nhttps://events.saip .org.za/event/7/contributions/5176/ LOCATION: Acro3 URL:https://events.saip.org.za/event/7/contributions/5176/ END:VEVENT BEGIN:VEVENT SUMMARY:Numerical Field Analysis of the Magnets for a proposed Ionisation Beam Profile Monitor for High Current Synchrotron and Cooler Rings. DTSTART;VALUE=DATE-TIME:20110715T091500Z DTEND;VALUE=DATE-TIME:20110715T093000Z DTSTAMP;VALUE=DATE-TIME:20261009T005740Z UID:indico-contribution-286-5193@events.saip.org.za DESCRIPTION:Speakers: John Garrett de Villiers (iThemba LABS)\niThemba LAB S was requested by the Institut für Kernphysik at Forschungszentrum Jüli ch\, Germany\, to design and calculate a magnet system for a proposed non- destructive Ionization Beam Profile Monitor (IBPM) that can measure beam p rofiles using the secondary ions produced in the rest gas\, planned to be implemented with the FAIR-GSI project in Darmstadt\n\nApart from the geome trical restrictions by the available space\, the main requirements for the magnet system are to comply with the specified field intensity and homoge neity at the plane of measurement and to deliver the primary beam unchange d and aligned with the original beam direction within the GSI storage ring . \n\nThe calculated magnets for the IBPM consists of four window-frame\, room-temperature\, water-cooled\, laminated\, dipole DC-electromagnets in line with the primary beam. The inner two dipoles of the set are respectiv ely used for horizontal and vertical beam profile analysis and the correct delivery of the beam from the system is facilitated with the aid of two c orrector magnets. The magnets are mounted outside and around the vacuum ch amber that contains other essential components and therefore will have unu sually large pole gaps that are in the order of 0.5 m\, which\, together w ith the relative short drift lengths between the magnets\, cause significa nt interference between the magnetic flux distributions of the magnets. Th is necessitated the use of 3D numerical field analysis that incorporates a l the magnets.\n\nThe field homogeneities in the regions where the beam pr ofiles are to be measured were found to be very sensitive to the magnet ge ometries and layout\, but a workable solution was found and the calculated results of these magnets and multi-pole and ion beam optics analysis of t he system will be presented.\n\nhttps://events.saip.org.za/event/7/contrib utions/5193/ LOCATION: Acro3 URL:https://events.saip.org.za/event/7/contributions/5193/ END:VEVENT BEGIN:VEVENT SUMMARY:Transmission electron microscopy investigation of radiation damage caused by keV implantation in single-crystal diamond. DTSTART;VALUE=DATE-TIME:20110715T094500Z DTEND;VALUE=DATE-TIME:20110715T100000Z DTSTAMP;VALUE=DATE-TIME:20261009T005740Z UID:indico-contribution-286-5196@events.saip.org.za DESCRIPTION:Speakers: Emmanuel Korawinga Nshingabigwi (University of the W itwatersrand)\nAn understanding of the types of defects produced during th e doping/implantation of diamond remains essential for the optimization of high-temperature\, high-power electronic applications.\n\nThus this study focuses on investigating the nature of the radiation damage produced duri ng the multi-implantation of carbon ions in synthetic type Ib and natural diamonds\, according to the CIRA (Cold-Implantation-Rapid-Annealing) routi ne. The implanted and annealed diamond samples were characterized using b right field transmission electron microscopy (BFTEM) in conjunction with s elected area diffraction (SAD).\n\nFor low fluence implantations\, the dam aged diamond retains its crystallinity after annealing at 1600K\, while i mplanting using doses above the amorphisation/graphitization threshold\, f ollowed by rapid thermal annealing (RTA) at 1600K\, results in a multi-lay er of graphite/amorphous carbon close to the surface.\n\nhttps://events.sa ip.org.za/event/7/contributions/5196/ LOCATION: Acro3 URL:https://events.saip.org.za/event/7/contributions/5196/ END:VEVENT BEGIN:VEVENT SUMMARY:Miniaturization of electrostatic space thrusters using ionization/ acceleration coupling in discharge mode DTSTART;VALUE=DATE-TIME:20110713T124500Z DTEND;VALUE=DATE-TIME:20110713T130000Z DTSTAMP;VALUE=DATE-TIME:20261009T005740Z UID:indico-contribution-286-5207@events.saip.org.za DESCRIPTION:Speakers: phil ferrer (wits)\nMiniaturization of space prolusi on systems has many advantages\, both from an economic and performance per spective. One of the most promising propulsion technologies\, the gridded electrostatic ion engine\, resists miniaturization due to the poor down-sc aling characteristics of the ion producing discharge chamber. We investiga te a system where the ionization and acceleration mechanisms are coupled\, thereby making the same electric field responsible for both. This sideste ps the need of a discharge chamber and allows for design of a much smaller engine. We introduce the concept and present some initial results\, comme nting on the feasibility of such a design.\n\nhttps://events.saip.org.za/e vent/7/contributions/5207/ LOCATION: Acro3 URL:https://events.saip.org.za/event/7/contributions/5207/ END:VEVENT BEGIN:VEVENT SUMMARY:Resin phantoms as skin simulating layers DTSTART;VALUE=DATE-TIME:20110714T064500Z DTEND;VALUE=DATE-TIME:20110714T070000Z DTSTAMP;VALUE=DATE-TIME:20261009T005740Z UID:indico-contribution-286-5212@events.saip.org.za DESCRIPTION:Speakers: Aletta Karsten (CSIR\, National Laser Centre)\nIn or der to apply light treatment to skin\, the absorption through the outer la yers of the skin needs to be considered. Human skin is a highly scattering medium and the melanin in the epidermal layer of the skin is a major abso rber of light in the visible and near infrared wavelengths. Darker skin ha s a higher concentration of melanin in the epidermis and absorbs more ligh t than fair skin. Ideally the effect of the skin treatment on the outer la yers of the skin should be tested on in vitro multi layer skin models. Thi s is not always feasible. For this work phantoms were used together with s kin cancer cells to test the effect of outer layer absorption on the effic iency of Photo Dynamic Therapy treatment.\nThree solid phantoms were prepa red from clear resin\, TiO particles (scattering particles) and carbon bla ck (absorption particles). Different carbon black concentrations were used to simulate different skin types. Cells were prepared and treated with th e photosensitiser. The phantoms were placed inside the wells containing th e photosensitised cells\, just touching the media in the well. The attenua tion of the different phantoms was calculated and the laser treatment time s were adjusted to keep the light dose delivered to the cells at 4.5 J/cm2 . After laser treatment cell viability was measured\, using the Cell Titer Blue Viability Assay\, for each of the wells. The phantoms attenuated the laser light by between 10 and 30%. Cell viability for the wells with the phantoms was less than without the phantoms and the differences are attrib uted to the reduced oxygen in the presence of the phantom. The initial res ults of the experiment indicate that the phantoms can be used to optically mimic the effect of the outer skin layers. For future work the experiment al set-up will be refined.\n\nhttps://events.saip.org.za/event/7/contribut ions/5212/ LOCATION: Acro3 URL:https://events.saip.org.za/event/7/contributions/5212/ END:VEVENT BEGIN:VEVENT SUMMARY:Optical Coherence Tomography as a diagnostic tool (Biophysics) DTSTART;VALUE=DATE-TIME:20110714T063000Z DTEND;VALUE=DATE-TIME:20110714T064500Z DTSTAMP;VALUE=DATE-TIME:20261009T005740Z UID:indico-contribution-286-5213@events.saip.org.za DESCRIPTION:Speakers: Ann Singh (CSIR\,National Laser Centre)\nOptical Coh erence tomography (OCT) is a non-invasive imaging technique that is known to be used to monitor changes and differences in different types of materi als. In the field of Biophysics/Biophotonics OCT can be used to non-invasi vely detect changes occurring in tissue. This study will look at using OC T to detect skin cancer. Similar work has been done by other groups\, how ever the influence of skin tone for such detection has not been evaluated to a great extent. The effect of skin tone on detection of skin cancer wi ll form a core part of the investigations as well as determining the effic acy of the system for early cancer detection. Preliminary work will be don e using phantoms that simulate the different skin tones. Melanin is the c omponent found in the skin\, largely responsible for the different skin to nes and will incorporated into our phantoms as carbon black\, black ink or synthetic melanin. The optical properties of such phantoms can be determ ined on the Integrating Sphere (IS) and OCT systems. A correlation will t hen be drawn between the optical properties and the OCT signals obtained. Once the preliminary tests are done to optimise the method for image anal ysis\, further studies will be done on patients and compared against conve ntional histology results. This talk will thus look at some OCT applicati ons\, some of the preliminary work done using our OCT system and the steps to determining the effect of skin tone on cancer detection.\n\nhttps://ev ents.saip.org.za/event/7/contributions/5213/ LOCATION: Acro3 URL:https://events.saip.org.za/event/7/contributions/5213/ END:VEVENT BEGIN:VEVENT SUMMARY:Predicting human epidermal melanin concentrations for different sk in tones DTSTART;VALUE=DATE-TIME:20110714T061500Z DTEND;VALUE=DATE-TIME:20110714T063000Z DTSTAMP;VALUE=DATE-TIME:20261009T005740Z UID:indico-contribution-286-5219@events.saip.org.za DESCRIPTION:Speakers: Jacoba Smit (CSIR)\nIn the past 50 years lasers has found numerous applications in medicine. One of their advantages is their use for minimalistic or non-invasive diagnosis and treatment. Often that m eans light penetration through skin and the correct dose required relies o n accurate information regarding the skin’s optical properties. Light ab sorption in the epidermal layer is a major factor in determining the laser light fluence that reaches the deeper skin levels. Darker skin has an epi dermal melanin volume fraction about twice that of lighter skin. Due to me lanin absorption\, less laser light reaches the deeper skin layers in dark skin tones. Laser-tissue interaction modelling software can correct for t his by adapting the dose applied to the skin. To correctly apply such soft ware it is important to characterise the skin in terms of skin tone with a n easy and reliable method. Measuring the melanin content of the skin is t he best method\, but it needs to be done non-invasively. However\, access to samples of all skin types is often limited and skin-like phantoms are u sed instead. The objective of this study is to compare experimentally meas ured absorption features of liquid skin-like phantoms representing Skin Ty pes I to VI with computational simulated skin from the Realistic Skin Mode l (RSM) part of the ASAP® software from Breault Research. Skin-like phant oms were prepared by adding Intralipid (20% fat emulsion) to samples of in creasing melanin concentration at pH ~ 7. UV-VIS transmittance spectra of the samples were measured over the wavelength range 370 to 900 nm and comp ared to simulated results from ASAP® using the same optical parameters. E xperimental and computational results indicated that at shorter wavelength s melanin absorption displayed non-monotonic features that may allow for m ore accurate ways of determining melanin concentration and therefore the e xpected absorption through the epidermal layer. This suggests that the pha ntoms may be able to represent optical characteristics of real skin.\n\nht tps://events.saip.org.za/event/7/contributions/5219/ LOCATION: Acro3 URL:https://events.saip.org.za/event/7/contributions/5219/ END:VEVENT BEGIN:VEVENT SUMMARY:Fabrication of MWCNT/NiO nanocomposite thin films for optically se lective solar absorbers DTSTART;VALUE=DATE-TIME:20110713T103000Z DTEND;VALUE=DATE-TIME:20110713T104500Z DTSTAMP;VALUE=DATE-TIME:20261009T005740Z UID:indico-contribution-286-5238@events.saip.org.za DESCRIPTION:Speakers: Kittessa Roro (NLC-CSIR)\nCarbon nanoparticles embed ded in thin NiO layers have shown an increasing interest for application i n spectrally selective solar absorbers that can be used for low temperatur e photothermal applications. It is expected that the size and shape of car bon nanoparticles in the NiO matrix is extremely important in tuning the s electivity of the coatings. In this work\, multiwall carbon nanotubes (MWC NT)/NiO composite films of different CNT contents were prepared by sol-gel technique\, and their structural and optical properties were investigated by scanning electron microscopy\, x-ray diffraction\, Raman spectroscopy\ , UV-Vis spectroscopy and emissometer. Preliminary durability study on the se coatings will also be presented. The results demonstrate promising spec trally selective properties indicating that the CNT/NiO composite is an ex cellent choice for solar water heating applications.\n\nhttps://events.sai p.org.za/event/7/contributions/5238/ LOCATION: Acro3 URL:https://events.saip.org.za/event/7/contributions/5238/ END:VEVENT BEGIN:VEVENT SUMMARY:Carbon structures generated by carbon ion implantation into FeCr t hin films DTSTART;VALUE=DATE-TIME:20110715T100000Z DTEND;VALUE=DATE-TIME:20110715T101500Z DTSTAMP;VALUE=DATE-TIME:20261009T005740Z UID:indico-contribution-286-5242@events.saip.org.za DESCRIPTION:Speakers: Daniel Wamwangi (wits university)\nWe present result s on the synthesis of precise and thickness controlled carbon structures u sing ion implantation into thin films of a typical metal catalyst\, for Sc hottky contacts and spintronic applications. Thin films of FeCr on a sili con substrate was prepared using magnetron sputtering and then implanted w ith carbon ions at controlled thicknesses close to the surface at elevated temperatures (600C) in an attempt to catalyse the formation of carbon nan otubes. The energy and the dose of the carbon ions to be deposited close to the surface was determined from SRIM simulations. The nature and qualit y of the carbon nanotubes was probed using Raman\, electrical and magnetic measurements.\n\nhttps://events.saip.org.za/event/7/contributions/5242/ LOCATION: Acro3 URL:https://events.saip.org.za/event/7/contributions/5242/ END:VEVENT BEGIN:VEVENT SUMMARY:Effect of Low Intensity Laser Irradiation (LILI) and Epidermal Gro wth Factor (EGF) on Adult Human Adipose Derived Stem Cells (hADSCs) DTSTART;VALUE=DATE-TIME:20110714T093000Z DTEND;VALUE=DATE-TIME:20110714T094500Z DTSTAMP;VALUE=DATE-TIME:20261009T005740Z UID:indico-contribution-286-5257@events.saip.org.za DESCRIPTION:Speakers: Bernard Mvula (Doctoral Student)\nThe study investig ated the effects of low intensity laser radiation (LILI) and epidermal gro wth factor (EGF) on adult adipose derived stem cells (hADSCs) isolated fro m human adipose tissue. Isolated cells were cultured in complete Dulbeco ’s Modified Eagle Medium (DMEM) containing 10% featal bovine serum (FBS) \, EGF and antibiotics and incubated at 37°C in 85% humidified atmosphere of 5% CO2. Semi-confluent monolayers of ADSCs were exposed to low intens ity laser at 5 J/cm2 using 636 nm diode laser. Cell viability and prolife ration were monitored using adenosine triphosphate (ATP) luminescence and optical density at 0\, 24 and 48 h post irradiation. Application of low in tensity laser irradiation and EGF on human ADSCs at 5 J/cm2 increased the viability and proliferation of these cells. Therefore low intensity laser therapy would probably enhance differentiation and proliferation of stem cells in vitro and these cells could be used in reconstructive surgery and tissue engineering.\n\nhttps://events.saip.org.za/event/7/contributions/5 257/ LOCATION: Acro3 URL:https://events.saip.org.za/event/7/contributions/5257/ END:VEVENT BEGIN:VEVENT SUMMARY:Remote detection of light organic elements using PET DTSTART;VALUE=DATE-TIME:20110715T063000Z DTEND;VALUE=DATE-TIME:20110715T064500Z DTSTAMP;VALUE=DATE-TIME:20261009T005740Z UID:indico-contribution-286-5261@events.saip.org.za DESCRIPTION:Speakers: Martin Cook (University of Johannesburg)\nWe look at the use of Positron Emission Tomography to detect light organic elements in two different contexts\, namely to locate diamonds within partially cru shed kimberlite (Mineral PET)\, and to locate buried land mines.\n\nLight organic elements such as carbon have traditionally proved difficult to loc ate\, and currently mines crush rock down to a fine size\, and then employ manual sorting methods to find diamonds. If diamond bearing rocks could b e identified before the final crush\, up to 98% of the electricity and wat er used for crushing could be saved\, and larger diamonds preserved. The p roposed technique is to use bremsstrahlung from a 40 MeV electron source t o excite the giant dipole resonance in target nuclei\, which have a large branching ratio to decay by emission of a neutron\, forming PET isotopes. Such isotopes release positrons\, which annihilate to create back-to-back 511 keV gamma rays. A 3D density map of possible sources allows the identi fication of hotspots. Complications arise from having to account for the e xcitation of many different nuclei\, and having to distinguish diamond fro m homogeneously distributed carbon. In order to be industrially feasible\, small diamonds need to be located\, requiring significant advances in det ection and image processing. We will look at simulations of the process\, imaging algorithms\, quantifying radiation doses and detector technologies .\n\nLand mines are a huge global problem. 2009 estimates place the number of buried land mines at over 100 million\, covering approximately 3 000 s quare kilometers of land worldwide. Between 1999 and 2008\, these have le ad to 73 576 mine casualties in 119 countries. Overall demining programme costs in third world environments are typically one to two million dollars per square kilometer of cleared land. Advances in land mine technology me an that mines can contain little or no metal\, making demining an expensiv e\, slow and dangerous activity. Most common elements in explosives are PE T emitters\, including Oxygen\, Carbon\, Nitrogen and Flourine\, raising t he possibility that PET could provide an effective method of mine detectio n.\n\nhttps://events.saip.org.za/event/7/contributions/5261/ LOCATION: Acro3 URL:https://events.saip.org.za/event/7/contributions/5261/ END:VEVENT END:VCALENDAR