Sandstone acidizing using mud acid is a quick and complex process where dissolution and precipitation occur simultaneously. Retarded mud acids are less reactive with the rock reducing the reaction rate hence increased penetration into the formation to remove deep damage. To understand thoroughly the retarded mud acid system, an in-depth investigation of the reaction of HF (hydrofluoric) and H2SiF6 (fluorosilic acid) with alumino silicates and the retarded system is undertaken using coreflood analysis and mineralogy analysis using the inductively coupled plasma. Coreflood analysis is used to understand and investigate the permeability changes in the sandstone rock as the retarded mud acid is injected at different conditions and the inductively coupled plasma (ICP) is used to investigate the effluent samples from the coreflood analysis to properly understand this system. Several issues that have not been addressed previously in literature are identified and discussed, including an optimum flowrate when sandstone is acidized, by acidizing the sandstone rock with a retarded acid system at various flowrates and determining the initial and final permeabilities. Also investigated is the retarded acids compatibility with ferric iron and a comparison of the retarded acid system to regular acid to consequently enable a thorough understanding of the retarded mud acid system using aluminum chloride (AlRMHF). Based on the work done, it is found that the absence of a hydrochloric (HCl) preflush is very detrimental to the sandstone core as calcium fluoride is precipitated and the retarded acid system is found to be compatible with iron(III) as an impurity. The regular acid (RMHF) dissolves considerably more silicon and produces more fines than the AlRMHF. 1cc/min is found to be the optimum flowrate when a sandstone core is acidized with AlRMHF. At this low flowrate, less silicon is dissolved, more aluminum is seen in the effluent and more calcium is dissolved. The retarded aluminum acid system considerably reduces the rate of reaction as evidenced in the dissolution reaction when compared to a regular mud acid system. This reduced rate of reaction implies deeper acid penetration and ultimately deeper damage removal.

Although inductively coupled plasma mass spectrometry (ICP-MS) is generally considered a reliable analytical technique, increasing demands on its capabilities require continued research and improvements. ICP-MS is susceptible to both matrix effects and drift, leading to a decline in accuracy and precision. A number of techniques are routinely used to compensate for these issues. Internal standardization is one such solution that requires relatively simple sample preparation and yet offers the possibility of improving both accuracy and precision. In order to be effective, an optimal analyte/internal standard pair must be chosen. Traditionally, analyte/internal standard pairs are chosen based on similarities in mass and/or ionization potential. The present studies sought to develop a program that determined standards based on the minimization of analytical error. 102 masses were monitored over 27 perturbations, i.e., changes to sample matrix and operating parameters. The standard deviations of the analyte/internal standard ratios were then used as a measure of internal standard performance. A thorough statistical analysis was conducted to determine trends between a good analyte/internal standard pair and similarities in chemical property. Similarities in mass offered the strongest relationship to a good internal standard choice, although many exceptions existed. The program was then tested over time and multiple instrument optimizations as well as on a completely different ICP-MS instrument. Results of these tests suggest that the data originally collected for the prediction program is not instrument-specific and thus provided a broader base of useful applications. Due to its unmatched sensitivity and multielement capabilities, ICP-MS is frequently utilized for biological samples. A more recent application, however, seeks to use ICPMS for the purpose of determining specific associations between metals and proteins. Such speciation requires a high resolution and reproducible separation prior to ICPMS analysis. Gel electrophoresis offers good separation and is well matched with the scanning properties of laser ablation sample introduction. The present study utilized native gel electrophoresis coupled with a uniquely modified electroblot system to improve sensitivity and to elucidate additional information. Chemically modified quartz fiber filters were successfully used as the transfer membrane to improve protein and metal capture efficiency. / text

This study is concerned with the compositional analysis of Roman and early post-Roman glass from both domestic assemblages and the remains derived from glass working and producing sites in Britain, using Inductively Coupled Plasma Spectrometry (ICPS). Samples analysed were from glassworking waste from Mancetter (midsecond century), Leicester (third century) and Worcester (first to third centuries), glass production debris, probably manufactured from the raw materials, in conjuncton with a domestic assemblage, from Coppergate (first to fourth centuries, or possibly later), and a domestic assemblage from Fishergate (spanning both the Roman and immediate post- Roman periods). All the glass analysed was shown to be of a typical and uniform soda-limesilica composition, except for a small number of vessel fragments from York which were higher in calcium. Any compositional differences between blue-green glasses typologically dated either to the Roman or Saxon periods, were found not to be consistent. Analysis of the colourless glass showed that the majority appeared to be actively decolorized using antimony, in conjunction with apparent differences in the compositions of the raw materials, when compared to glass of the same date in other colours. Compositional differences between melted waste from Mancetter, Leicester and Worcester, were apparent, but not to an extent which allowed characterization to be successful. Analysis of glassmelting pots from Coppergate showed some high temperature glassworking (and possibly glassmaking) could have occurred. Other debris, thought to be indicative of glassmaking was also analysed and compared to the composition of the Roman domestic assemblage.

[Truncated abstract] The analysis and subsequent interpretation of trace evidence is of paramount importance to the forensic scientist. While a variety of methods are available to facilitate comparison between recovered and control samples, the use of a specific analytical method depends upon both the physical and chemical nature of the material itself and the material to which it is to be compared. Elemental analysis of evidentiary material is one such method of sample comparison and has been extensively applied to this purpose following the introduction of neutron activation analysis in the early 1960s. However, over the last 15 years, another instrumental technique has taken centre stage in the analytical armoury of the forensic scientist: laser ablation–inductively coupled plasma-mass spectrometry (LA-ICP-MS). The modification and adaptation of this technique, to a point where it is possible to distinguish between glass materials produced only hours apart on the same production line, is detailed in this thesis. Additional protocols have also been developed for the analysis of fibreglass and plastic crime scene debris. Finally, a method for quantification of elemental concentrations in headlamp plastics has also been developed to facilitate inter-comparison of data between both different analytical techniques and different laboratories. Glass material is one of the most common varieties of trace evidence and the forensic examination of glass traditionally involves the determination of its refractive index (RI). ... The analytical protocol involves the analysis of 46 analytes on material comprising the exterior surface of the lens. Using this data, it was found that although minor variations in elemental composition exist within a single headlamp lens, discrimination between lenses produced from a single manufacturing plant over a short period of time could still be achieved. Discrimination between all headlamp lenses, with the exception of some lenses produced on the same day, could be facilitated using the analytical protocol developed. Furthermore, an interpretational protocol has been developed that has successfully classified all unknown headlamp lens samples investigated in this study, within the discrimination limits of the analytical method. The semi-quantitative analysis of glass and plastic samples has also been examined using LA-ICP-MS. The concentrations of 16 analytes in container and float glass samples were determined. However, the levels of discrimination afforded by the semi-quantitative data were inferior to those achieved using qualitative data. Finally, a series of plastic-based standards, containing 25 analytes of known concentrations, was produced. Using these standards, relative concentrations of the study analytes were determined in polycarbonate headlamp lenses. Interpretation of the data produced made it possible to discriminate between all study samples. Consequently, the total analytical and interpretational protocol developed in this study has established the foundation for LA-ICP-MS to be adopted internationally as a recognised method for the analysis of plastic crime scene debris.

[Truncated abstract] The sale of fraudulent South-East Asian ceramics constitutes a large proportion of the illegal artefact and antique trade and threatens to undermine the legitimate international market. The sophistication and skill of forgers has reached a level where, using traditional appraisal by eye and hand, even the most experienced specialist is often unable to distinguish between a genuine and fraudulent piece. In addition, the current scientific method of authentication used by the international antiques and art industry, thermoluminescence (TL) dating, carries severe limitations. The technique has an error margin of +/-20 % and requires the removal of a significant piece of the sample being tested, which decreases both the monetary and cultural value of the artefact. Of more concern, forgers have developed methods which produce false test results and which appear to corroborate false claims for the age of artefacts. Consequently, the use of TL dating for authentication of ancient ceramics, especially those of South-East Asian origin, has now come into serious question. The most suitable method for authenticating ceramics is through provenance establishment. Studies published in the literature have investigated the application of various analytical techniques to provide this information for ceramic wares and have highlighted their potential to be used for provenance establishment. However, the value of each of these techniques is limited rendering them generally unsuitable for practical use in the international antiques and art world to authenticate high-value South-East Asian artefacts. Consequently, there is a desperate need for the development of a robust, accurate and non-destructive method which can be practically applied in the industry to authenticate South-East Asian ceramics. ... Minor variations between spectral profiles of artefacts produced in the same country have also been used to further provenance artefacts to a specific production region or kiln site. The results of analyses have been compiled to form a unique reference database which can be added to in the future and used by experts internationally. Adaptation of the developed sampling and analytical methodologies to allow in-situ sampling of large artefacts using the

Magister Scientiae - MSc (Biotechnology) / Soybean have been listed as a priority commodity crop in South Africa (SA) and provide a good source of protein to the population. Therefore, soybean has been earmarked as an important food security crop and strategies are currently being discussed at governmental level to increase and sustain soybean production. However, the SA landscape poses many challenges to the agricultural sector such as prolong drought periods, flooding, nutrient poor soils, saline soils and heavy metal contaminated soils. Heavy metal (HM) contamination is becoming a serious concern and is aggravated by historical mining in SA. Indeed, SA has established itself as the number one ranked mining country in the world and is frequently mining metals such as chromium, vanadium, gold, zirconium, platinum, and antimony. Prolong rainfall near mining areas leads to acid mine drainage which lowers the soil pH to approximately two. These highly acidic soils will solubilize the metals and cause the metals to leach into river systems as well as the water table leading to increase heavy metal contamination in nearby soil sites. This increase metal content negatively affects seed germination and overall plant development. Nonetheless, plants have evolved numerous internal mechanisms that help them to survive HM toxicity; by either avoiding or tolerating the stress. Two stress-activated pathways that help the plant tolerate stress have attracted much interest i.e. the glyoxalase system and reactive oxygen species (ROS) - antioxidant system as they detoxify methylglyoxal (MG) and ROS. / 2021-08-31

This work deals with the content of iodine in soils, furthermore with obtaining and processing samples from four selected sampling areas, all of which are in the proximity of the Arnoštov settlement in district Prachatice in the foothills of Šumava. The soil samples were obtained from forest, meadow, pasture and fallow soil in 2009 to 2011. The iodine content in the soils was determined by using the spectrophotometric method, which had been optimized for the soil samples. Iodine concentration in lysimeter water was determined by using method inductively coupled plasma - mass spectrometry. The results obtained from each sampling areas were compared with each other and with the results from other areas. Consequently, the iodine concentration results in the soils were compared with the iodine concentration in lysimeter waters. It was found, that the highest iodine content in soils was measured in a sample obtained from Area 1 (meadow), part B in a depth of 16 - 30 cm in June of 2009, namely a content of 8,67 mg of I per kg of dry soil. The lowest content of 1,42 mg of I per kg of soil was found in the area 4 (forest), sample obtained in June of 2010, in the L horizon. By comparing iodine content with iodine concentrations in lysimeter waters, it was concluded that the concentration of iodine in lysimeter waters does not depend on iodine concentrations in soils and that it does not even represent the absolute iodine content in soil, as was determined by comparing the results from Arnoštov with data acquired from Agrovýzkum Rapotín in Jeseníky.

Les nanostructures de semi-conducteurs de faibles dimensions (comme les nanofils(NFs)) sont devenues l'objet de recherches intensives pour explorer de nouveaux phénomènes émergents à l'échelle nanométrique et sonder leur possibilités d’ utilisation dans l'électronique du futur. Parmi les différents nanofils semi-conducteurs, SiC a des propriétés très particulières, comme une large bande interdite, une excellente conductivité thermique, un haut champ électrique de claquage, une stabilité chimique et physique, une haute mobilité des électrons et une haute biocompatibilité.Nous proposons dans cette étude ; d'examiner une nouvelle approche pour fabriquer des nanostructures de SiC par l'approche « top-down ». Cela permet l'élaboration de nanostructures cristallines de SiC de haute qualité monocristalline avec un niveau de dopage contrôlé. Le comportement de nanostructures de SiC gravées a également été étudié en fonction de polytypes et des orientations cristallographiques.Nous avons également étudié les trois principaux sujets de SiC nano-devices pour atteindre une excellente performance. Pour répondre à ces questions, deux types de SiC nanoFET (SiC NFFET et SiC NPFET) ont été fabriqués et caractérisés par l'utilisation de nanofils de SiC et de nanopiliers de SiC préparés respectivement par les méthodes « bottom-up » et « top-down ». / Low dimensional semiconductor nanostructures, such as nanowires (NWs), have become the focus of intensive research for exploring new emergent phenomena at the nanoscale and probing their possible use in future electronics. Among these semiconductor NWs, Silicon Carbide (SiC) has very unique properties, such as wide bandgap, excellent thermal conductivity, chemical and physical stability, high electron mobility and biocompatibility. These factors makes SiC a long standing candidate material to replace silicon in specific electronic device applications operating in extreme conditions or/and harsh environments. SiC nanostructures have been studied extensively and intensively over the last decade not only for their fabrication and characterization, but also for their diverse applications. I have outlined the growth of SiC nanostructures based on different growth methods, a noteworthy feature of their characteristic properties and potential applications in the chapter one. As-grown SiC NWs fabricated by bottom-up method present a high density of structural defects, such as stacking faults. This kind of defect is one of the factors which lead to poor electrical performance (such as weak gate effect and low mobility) of the related devices. Therefore, it is required to develop a high quality of SiC nanostructures with low density of the structural defects using an alternative method, such as top-down process. Main objectives of this thesis are divided into three main parts. The first part of the thesis (Chapter two), we present the simulation results of the electrical transport and thermoelectric properties of SiC NWs. I have investigated the thermoelectric enhancement by studying the complex interplay of the size of NWs, temperature and surface roughness. Our simulation results show that the ZT of C terminated SiC NW (2.05×2.05 nm2) reaches a maximum value of 1.04 at 600K. The second part of the thesis (Chapter there) is devoted to the fabrication of high quality SiC nanostructures with controlled doping level. I have developed a top-down fabrication technique for high quality nanometer scale SiC nanopillars (NPs) using inductively coupled plasma etching. The etching behavior of SiC NPs has also been studied depending on polytypes and crystallographic orientations. Under the optimal etching conditions using a large circular mask pattern with 370 nm diameter, the obtained 4H-SiC nanopillars exhibit high anisotropy features (6.4) with a large etch depth (>7μm). A hexagonal, rhombus and triangle based pillar structures have been obtained using α-SiC (0001), 3C-SiC (001) and 3C-SiC (111) substrates, respectively. The last part of the thesis (Chapter four) is dedicated to the design and the electrical characterization of SiC nanodevices. To investigate the electrical properties of SiC nanostructures, two different kinds of SiC nanoFETs (SiC NWFET and SiC NPFET) have been fabricated by using SiC NWs and SiC NPs prepared via bottom-up method and top-down methods, respectively. In case of SiC NWFET, low resistivity ohmic contacts (378 kΩ) have been obtained after the annealing at 650 °C. Ni silicide intrusion into the SiC NW channel has been observed the annealing at 700 °C. This temperature is compared to one of other group IV materials. In case of SiC NPFET, two different types of NPFET (3C-SiC (001) and 4H-SiC (0001)) have been fabricated using our SiC nanopillars, obtained by top-down approach. The estimated values of the field-effect carrier mobility are 232.7 cm2⋅V-1s-1 for 3C-SiC (001) NPFET (#2) and 53.6 cm2⋅V-1s-1 for 4H-SiC (0001) NPFET, which is higher than the best values reported in the literature (15.9 cm2⋅V-1s-1).

A espectrometria de massas com plasma acoplado indutivamente com simples quadrupolo (q-ICP-MS) e cela de reação dinâmica (DRC-ICP-MS) foi avaliada para determinação seqüencial de Al, As, Cd, Co, Cu, Cr, Mn, Mo, Pb, Pt, Sb, Se, Sn, Te, Tl, V e Zn em sangue. Para as análises, amostras de sangue (200 µL) foram diluídas 1:50 em uma solução contendo 0,01% v/v Triton® X-100 e 0,5% v/v de ácido nítrico. As calibrações foram realizadas com ajuste de matriz, utilizando sangue ovino. Como gás de reação utilizou-se a NH3. O uso do DRC foi fundamental para a determinação de Cr e V. A escolha da melhor vazão do gás e a otimização do parâmetro de rejeição (RPq) foram estudadas utilizando sangue base ovino ou uma solução de matriz sintética (SMS), de acordo com a concentração do analito no sangue base. Os limites de detecção (3s/coeficiente angular) para determinação de 27Al, 75As, 111Cd, 59Co, 63Cu, 55Mn, 98Mo, 208Pb, 195Pt, 123Sb, 82Se, 120Sn, 130Te, 205Tl e 66Zn em sangue por q-ICP-MS foram 0,223; 0,014; 0,003; 0,011; 0,304; 0,009; 0,009; 0,003; 0,001; 0,005; 0,264; 0,006; 0,010; 0,001; 0,834 µg L-1, respectivamente, e para determinação de 52Cr e 51V em sangue por DRC-ICP-MS utilizando o gás de reação amônia os limites de detecção foram de 0,007 e 0,006 µg L-1. Para a determinação de 27Al, 63Cu, 65Cu, 64Zn e 66Zn em sangue por q-ICP-MS através da calibração com ajuste de matriz com SMS os limites de detecção foram 0,083; 0,090; 0,055; 0,281; 0,306 µg L-1, respectivamente. A validação do método foi realizada por meio da análise de materiais de referência do INSP-Canadá, NYSDOH-EUA e Seronorm-Noruega. / The use of inductively coupled plasma mass spectrometry with quadrupole (q-ICP-MS) and dynamic reaction cell (DRC-ICP-MS) was evaluated for sequential determination of Al, As, Cd, Co, Cu, Cr, Mn, Mo, Pb, Pt, Sb, Se, Sn, Te, Tl, V and Zn in whole blood by q-ICP-MS or DRC-ICP-MS methods. Prior to analysis, sample (200 µL) were diluted 1:50 v/v in a solution containing 0.01% v/v Triton® X-100 and 0.5% v/v nitric acid. For all elements, except Cr and V, the instrument was operated in q-ICP-MS mode. The use of DRC was only mandatory for Cr and V. NH3 was evaluated as the reaction gas. Selection of best flow rate of reaction gas and optimization of the quadrupole dynamic bandpass rejection parameter (RPq) were carried out, using base whole blood or synthetic matrix solution (SMS), in according with element base blood concentration. Method detection limits (3s/slope) for 27Al, 75As, 111Cd, 59Co, 63Cu, 55Mn, 98Mo, 208Pb, 195Pt, 123Sb, 82Se, 120Sn, 130Te, 205Tl and 66Zn determination in whole blood by q-ICP-MS against matrix matching calibration (base blood) were 0.223; 0.014; 0.003; 0.011; 0.304; 0.009; 0.009; 0.003; 0.001; 0.005; 0.264; 0.006; 0.010; 0.001; 0.834 µg L-1, respectively, and for 52Cr and 51V determination in whole blood by DRC-ICP-MS the detection limits were 0.007 e 0.006 µg L-1. For 27Al, 63Cu, 65Cu, 64Zn and 66Zn determination by q-ICP-MS through matrix matching calibration with SMS the detection limits were 0.083; 0.090; 0.055; 0.281; 0.306 µg L-1, respectively. Method validation was accomplished by the analysis of reference materials from INSP-Canada, NYSDOH-USA, Seronorm-Norway.

Ce travail s'inscrit dans une démarche visant à quantifier l'impact de la diagenèse sur les ratios élémentaires Sr/Ca, Mg/Ca et U/Ca caractéristiques de l'exosquelette (aragonite biogénique) de coraux Porites sp. Ces ratios élémentaires sont très utilisés comme paléo thermomètres en paléo climatologie tropicale pour reconstruire les paléo variables environnementales comme la température de surface de l'océan. On considère dans un premier temps un corail moderne prélevé in vivo et un corail fossile daté au 14C de l'Holocène Moyen (5445 ans BP). Les deux coraux ne présentent aucune trace d'altération diagénétique. On mesure Sr/Ca, Mg/Ca, U/Ca dans l'exosquelette par spectrométrie de masse couplée à un plasma inductif et à la microsonde de Castaing pour Sr/Ca. Les températures de l'océan du temps du vivant des coraux sont alors reconstruites à partir de la géochimie des échantillons et validées. L'approche est ensuite étendue à des coraux pléistocènes (~125000 ans BP) altérés par la diagénèse e.g., apparition de calcite au détriment de l'aragonite initiale sous l'action de l'eau douce percolant dans les récifs. Cette calcitisation affecte les ratios Sr/Ca et Mg/Ca originels et est susceptible d'entacher les reconstructions d'un biais qu'il est important de bien connaître. En s'appuyant sur la spectrométrie Raman et la microanalyse X, on confirme les tendances qualitatives rapportées dans la littérature sur l'impact de la calcite sur les proxies du climat : la présence de calcite diminue (resp. rehausse) le ratio Sr/Ca (resp. Mg/Ca) créant donc des artéfacts chauds dans les températures reconstruites. / This work is part of an approach aimed at quantifying the impact of diagenesis upon the Sr/Ca, Mg/Ca and U/Ca elemental ratios that typify the exoskeleton (biogenic aragonite) of Porites sp corals. These elemental ratios are indeed routinely used as paleothermometers in tropical paleoclimatology in order to reconstruct environmental paleovariables such as the Sea Surface Temperature (SST). In a first step, we analyze a modern coral collected in vivo and a fossil coral dated by 14C to mid-Holocene (5545 year BP). Both corals are in pristine state. The Sr/Ca, Mg/Ca and U/Ca ratios are measured by inductively coupled plasma mass spectrometry (ICP-MS) and with a Castaing microprobe for Sr/Ca. The SSTs at the time when the corals were alive are reconstructed from the geochemistry of the samples and validated against in situ measurements / previous work in the same area. Next, the approach is extended to Pleistocene fossil corals (~125000 year BP) that have been altered by diagenesis e.g., calcitization of the samples to the detriment of the original aragonite due to the fresh water that percolates through the coral reefs. Calcitization alters the original Sr/Ca and Mg/Ca. The reconstructed SSTs can therefore include nontrivial biases whose magnitude must be evaluated. Relying on Raman spectrometry, we confirm published qualitative trends on the impact of calcite upon the climate proxies : calcite lowers (resp. increases) the Sr/Ca (resp. Mg/Ca) ratio leading therefore to warm artifacts in the reconstructed SSTs.