>Magister Scientiae - MSc / Background: Plaster models form an integral part of the traditional orthodontic records. They are necessary for diagnosis and treatment planning, case presentations as well as for the evaluation of treatment progress. The accuracy of the measurements taken for space assessment is crucial prior to treatment planning. The introduction of digital models overcomes some problems experienced with plaster models. Digital models have shown to be an acceptable alternative for plaster models. Aim: The aim of the study was to determine the accuracy of traditional measurement techniques when compared to the CAD/ CAM measurements in the assessment of tooth widths and arch perimeter from plaster models. Method: The mesio-distal tooth widths and arch perimeter of thirty archived plaster models were measured using a digital caliper to the nearest 0.01 mm and divider to the nearest 0.1 mm. Corresponding digital models were produced by scanning them with a CAD/CAM (InEos X5) and space analysis completed by measurements using InEos Blue software. Measurements were repeated after 1 week from the initial measurement. The methods were compared using descriptive analysis (mean difference and standard deviation). Results: The operator reliability was high for digital models as well as the plaster models when the measurement tool was the digital caliper (analyzed using the Pearson correlation coefficient in the paired t-test). The mean values of tooth widths measurements of CAD/CAM, digital caliper and divider were 6.82 (±0.04), 6.94 (± 0.04) and 7.11 (± 0.04). There was a significant difference between the measurements made by the CAD/CAM and the divider. Additionally significant differences between the measurements by digital caliper and divider measurements (p < 0.05) were observed. No significant difference was found when comparing CAD/CAM to digital caliper. Positive correlation was displayed between CAD/CAM, digital caliper and the divider, but the measurements completed with the digital caliper had the highest correlation with the CAD/CAM. The difference was not significant between the aforementioned measurement tools (p > 0.05). Arch perimeter measurements showed no statistical significant difference between CAD/CAM, digital caliper and divider (p < 0.05). Conclusion: Archived plaster models stored as records can be converted to digital models as it will have the same accuracy of measurements. The value of doing a space analysis with the CAD/CAM system can be performed with similar reliability on the digital models as a caliper on plaster models.

Made available in DSpace on 2014-06-11T19:22:15Z (GMT). No. of bitstreams: 0 Previous issue date: 2007-06-20Bitstream added on 2014-06-13T19:07:35Z : No. of bitstreams: 1 pereira_frs_me_botfca.pdf: 284602 bytes, checksum: 48757cf8488e373534df370b0344e8a0 (MD5) / Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / A hipótese desse trabalho é de que o gesso de minério, associado a fonte solúvel adequada de fósforo, aplicado superficialmente em sistema plantio direto, funciona como indutor de crescimento radicular em profundidade e influencia na produtividade do milho. O objetivo desse trabalho foi avaliar a influência do gesso de minério, associado a diferentes fontes de fósforo, sobre os atributos químicos do solo, desenvolvimento do sistema radicular e produtividade da cultura do milho sob sistema de plantio direto. O estudo foi desenvolvido na Área Experimental do Centro de Ciências Agrárias, pertencente à Universidade Federal de Alagoas. O solo onde as parcelas experimentais foram instaladas é classificado como Latossolo Amarelo Coeso distrófico. O clima, de acordo com a classificação de Koeppen do tipo As, Tropical chuvoso, com verões secos. Foi utilizado o híbrido de milho BRS 3150, cultivado em sistema de plantio direto. O delineamento estatístico foi o de blocos casualisados, com parcelas subdivididas e quatro repetições. As parcelas foram constituídas pelas fontes de fósforo (superfosfato triplo - ST, superfosfato simples - SS e sem fósforo S/P). As subparcelas foram constituídas pela presença (C/G) ou ausência (S/G) de aplicação de gesso de minério. O gesso foi aplicado em superfície 30 dias antes da semeadura do milho, que foi realizada utilizando-se semeadora pneumática de tração tratorizada, com quatro linhas individuais, espaçadas de 0,80 m, colocando-se 5 sementes por metro. Na adubação, por ocasião da semeadura, toda área experimental recebeu 30 e 120 kg ha-1 de N e K2O, na forma de uréia e cloreto de potássio, respectivamente. Nos tratamentos que receberam fósforo, foram aplicados 50 kg ha-1 de P2O5 na forma de superfosfato triplo ou superfosfato simples, dependendo do tratamento. Na adubação de cobertura foram aplicados 120 kg ha-1 de N.... / The hypothesis of this work is of that the ore gypsum, applied superficially in no-tillage system, functions as inductive of root growth in depth, thus reducing the effects of short period without rain, usual in the State of Alagoas. The objective of this work was to evaluate the influence of the ore gypsum, associate with different phosphorus sources, on the soil chemical attributes, root development and maize crop yield in no-tillage system. The study was developed in the experimental area of Centro de Ciências Agrárias, belonging to the Universidade Federal de Alagoas. The soil where the experimental plots were installed is classified as Distrofic Yellow Latossol Amarelo Coeso distrófico. The climate, in accordance with the classification of Koeppen is of the type rainy tropical, with dry summers. Was used the BRS 3150 hybrid of maize, cultivated under no-tillage system. The statistical design was of randomized blocks, in split-splot scheme, and four replications. The plots were composed by phosphorus sources (triple superphosphate - ST, simple superphosphate - SS and without phosphorus S/P). The subplots was composed by with (C/G) and without (S/G) application ore gypsum. The native vegetation was desiccated, before maize sowing, with herbicide Glyfosate using 3 L ha-1. The maize was sowed 30 days after application in surface gypsum, using seeder pneumatic of mechanics traction, with four individual lines, spaced of 0.80 m, putting 5 seeds for meter. During the sowing, all experimental area received 120 and 30 kg ha-1 of N and K2O, in form of urea and potassium chloride, respectively. In the treatments that received phosphorus, 50 kg ha-1 were applied of P2O5 in form of triple superphosphate or simple superphosphate, depending of the treatment. In covering fertilization 120 kg ha-1 of N were applied. Were evaluated on the soil the chemical attributes and on... (Complete abstract click electronic access below)

The present study aims to investigate the composition of historical plasters to get information about their material characteristics and their technology. Plaster samples were obtained from four Ankara Citadel houses built in late Ottoman period. In order to determine the raw material characteristics and mineralogical properties of plasters / chemical analyses, optical observation of cross sections, petrographic analyses of thin sections, elemental analyses by ICP-OES, X-ray powder diffraction analyses for the determination of mineral phases, thermogravimetric analyses and FTIR analyses were carried out. Interpretation of all the analytical examination was used to understand the composition and unique character of plaster samples studied. Observation of thin sections revealed more plaster layers than those observed in cross sections. Up to twelve layers could be observed with different colours, such as blue, red, yellow, green, white and brown. Generally, thicknesses of white plaster layers were found to be thicker than the others. In two samples, two black boundaries between plaster layers were identified which could be an indication of the use of asphalt for isolation purposes, like dampness proofing or heat insulation. Soluble salt contents of the plaster samples were in the range 3.04%-9.22%, with an average being 6.62%. The anions identified were Cl-, SO42-. In few samples, PO43-, NO2- and NO3- were found. Binder was found to be lime and gypsum. The amount of binder in terms of total calcium oxide, CaO, was found to be in the range of 33.5-43.6%, with an average being 37.9%. Amount of aggregate was about 62.1% as average. The main minerals identified in plaster samples were calcite and gypsum. Gypsum might be added to increase the strength of the plaster. Beside calcite and gypsum, quartz and pozzolanic activity related mineral, Opal-A, were found in some of the samples. In red plaster layers hematite mineral was also identified. Other colour effective elements were found to be Fe, Sb, Mn, Cu, Cr and Ni. Presence of organic additives was observed but clear identification was not established.

Slight revision of Thesis (doctoral), Bonn, 1977. / Includes bibliographical references and indexes.

Havsmiljöer är idag den slutliga anhalten för den nedskräpning av plast som kommer ifrån avloppsvatten och allmän nedskräpning. Stora mängder plastpartiklar i olika storlekar har upptäckts i haven och även inuti djur som misstagit plasten som föda. Forskning visar att en stor del av plasten är av mikroskopisk storlek, så kallade mikroplaster. Inom denna grupp förekommer textilfibrer som likt andra plaster är svårnedbrytbara i naturen. Det har genom studier påvisats att små textila fiber rinner ut med avloppsvattnet och hamnar i haven. PET är en av de vanligaste plasterna och utifrån denna tillverkas polyesterfiber som är det i särklass mest använda materialet inom textiltillverkning. Att plastfragment från textilier skadar havsmiljön är en ny upptäckt och ämnet behöver undersökas i fler dimensioner än vad forskningen hittills gjort. Projektet syftar därför till att klargöra vilka egenskaper som påverkar mängden emission av polyesterfiber vid hushållsnära tvättning. Detta uppnås genom experimentella undersökningar av olika materialkombinationer som tvättas under lika omständigheter. Tvättvattnet analyseras och fibrerna räknas för att erhålla en jämförande studie kring polyestermaterials tendens till fällning av fibrer. Tre faktorer stod till grund för framtagning av metod: utveckling och förbättring av nuvarande metod, att efterlikna hushållstvätt samt tillförlitlighet i resultat. Detta har uppnåtts genom att laborationstvättmaskiner använts istället för kommersiella då detta ger ett vetenskapligt mer säkerställt resultat, något som har bejakats i största möjliga mån i varje steg. Alla polyestermaterial är stickade, färgade och mekaniskt bearbetade på Textilhögskolan för att garantera att samtliga material är tillverkade under samma förhållanden. Olika filtreringsmetoder har testats för att fastställa säkerhet i resultatet. Framtagning av material, tvättning, filtrering och analys var de centrala huvudmomenten för det praktiska arbetet. Analysen har gjorts manuellt där varje partikel på filtret har räknats. Resultatet visade att mikrofibergarn generellt fällde mer än filamentgarn. En högre delning vid stickning gav mer emission än en lägre och att material som slitits resulterade i mer shedding. Kombination av dessa tre faktorer; mikrofibergarn, hög delning och material som slitits gav ett resultat markant större mängd fiberemission än de tyger med endast två av dessa faktorer sammansatta. Tygerna som endast innehöll en av dessa faktorer gav betydligt lägre mängd fällning. Fleecematerial stickat i mikrofibergarn visade sig fälla mindre än en slätstickad vara med samma garntyp stickad i högre delning. Metoden som använts vid framtagning av fleecematerial är ifrågasatt, då kvalitén av dessa inte tycktes motsvara en industriellt framtagen fleecevara. Därför ställer man sig kritisk till detta resultat. De tyger som gav störst respektive minst andel emission av fibrer tvättades ytterligare för att studera inverkan av upprepad tvättning. Emissionen ökade med antal tvättar tills den så småningom avtog när fibrer slitits bort. Resultatet visar att man i största möjliga mån inte bör kombinera polyestervaror i trikå med garn 100den/144f, delning 28 som är smärglad. / The marine environment today, has become the end station for plastics, waste from wastewater and general litter. Large quantities of plastic particles of different sizes have been detected in the ocean, with resulting animals ingesting this mistaking it for food. Science shows that a large part of these plastic fragments are of microscopic size, named microplastics, and within this group there are textile fibres that like other plastics are resistant and detrimental to nature. Studies have shown that when washing, the wastewater carries these small textile fibres and allows them to pass trough the purification.   PET is one of the most used plastics and common in polyester fibre manufacture, by far the most used material in textile manufacturing. A new discovery, finds that the plastic fragments damage the marine environment, and the subject needs to be analysed in more detail than research has covered so far. This project aims to clarify which properties affect the amount of polyester fibre emissions when domestic washing. To investigate this, experimental tests were carried out on different material combinations washed under the same circumstances. Water from the wash was analysed and fibres were counted in order to complete a comparative study of polyester materials tend to shed.   Three factors were considered for developing the method: development and improvement of existing method, aiming to resemble household wash and ensure reliability of results, all done by laboration washers instead of using commercial washing machines. Safety of results has been considerably affirmed during every step. Every polyester material was knitted, coloured and mechanically processed by the research group to guarantee that all of the materials was manufactured under same conditions. Different filter methods have been used to determine safety in results. Manufacturing of material, washing, filtering and analysis were the central focus for the practical work. The analysis came from manual count of every fibre particle.   The result showed that microfiber yarn generally shed more than the filament yarn. A higher gauge gave more emission than a lower and that a worn material resulted in more shedding. The combination of these three factors; microfiber yarn, high gauge and a worn material gave markedly higher results than when tested with only two factors. The tests that only contained one of these factors gave significantly lower amount of emission. Fleece knitted in microfiber yarn had a lower level of shedding than a single jersey material in same yarn type with higher gauge. The method used for manufacturing is questioned, because the quality that should correspond an industrial produced fleece was not matched. Therefore, the result is critically inspected. The two combinations from the chosen parameters that gave the most respective and the least amount fibre emission were analysed additionally with more wash to assess their further effect. Here the emission seemed to increase with the amount of wash until it eventually subsided when more or less the fibres had worn away. Based on this result, one can finally say that these three factors should not be combined to manufacture knitted material in polyester.

The use of geochemical analysis for characterization studies of archaeological material has been increasing for decades. In recent years, advancements in X-ray fluorescence (XRF) instrumentation have led to hand-held portable XRF (pXRF) instruments capable of on-site, rapid, non-destructive analysis. The addition of pXRF to the archaeologist's toolkit has the potential to revolutionize geochemical characterization studies as research design can be informed by field analysis, once off-limits museum collections may now be analyzable, and data can be gathered on in-situ objects without disturbing their context. This new instrumentation has shown promise in characterization studies on a variety of archaeological materials, including ceramics. Particularly, it has been shown to generate data useful in distinguishing the geochemical provenance of artifacts. While most existing provenance studies that employ pXRF involve obsidian, it is possible that pXRF is a suitable analytical tool for ceramics as well, since instrumental neutron activation analysis (INAA) and laboratory XRF have both been used in provenance studies of obsidian and ceramics. This thesis reports research that utilized a Bruker hand held pXRF analyzer to study ceramics and plaster floors from Classic Period (ca. AD 250-1000) archaeological sites in southeast Mesoamerica. The data gathered from this analysis are used to examine the ability of pXRF to address archaeological questions of archaeological provenance on ceramic material and human activity patterns on archaeological plaster. The data gathered on ceramic material is analyzed to determine if "valley profiles" (or "chemical fingerprints") can be created for samples excavated in the same valley and to investigate inter-valley trade. Data from the plaster samples is examined to determine if pXRF can detect human activity patterns on plaster floors and, if so, if the activity is identifiable. The results suggest that, while pXRF results can be used to create "valley profiles" for provenance research, it is difficult to ascertain if it can be used to identify items of trade. This investigation also shows that, while pXRF data can identify human activity on plaster, it is difficult to determine what those activities were. This leads to the conclusion that pXRF has potential for both provenance and prospection studies on earthen materials. However, methodological development is necessary to fine tune research design. This thesis contributes to a greater understanding of the potentials and limitations of pXRF instrumentation in characterization studies of archaeological materials as well as understanding cultural-historical details in Classic southeast Mesoamerica.

The work presented aims to find alternatives for the prototyping of components by sand and plaster mold manufacturing processes that deliver properties similar to high pressure die casting (HPDC). Sand and plaster test samples have been casted. The Al-7Si-0.35Mg alloy has been tested in as cast condition and in a heat treated condition; T5 for sand cast samples and T6 for those plaster cast. The Al-7Si-2Cu-0.35Mg alloy was also tested in as cast condition. Tensile, fatigue and hardness tests have been performed. Microstructural investigation comprising secondary dendrite arm spacing, defects, Fe-rich β-phases and Si size measurements has been performed on the different conditions. The results have been compared to available data for Al-9Si-3Cu-(Fe) alloy used in HPDC. The T5 heat treated sand cast condition has shown to have properties similar to HPDC. All other sand cast conditions, including the previously tested Al-9Si-3Cu-(Fe) alloy, have been shown to be reasonable alternatives.

Einleitung Artikulationsgips dient der sicheren Verankerung von zahnärztlichen Gipsmodellen im Kausimulator. Eine Norm zur Quantifizierung der Haftfähigkeit dieses speziellen Dentalgipses an Gipsmodellen existiert bisher nicht. Ziel der vorliegenden Untersuchung ist es, Unterschiede zwischen Artikulationsgipsen bezüglich ihrer Adhäsion an Modellgipsen festzustellen und die neu entwickelte Methode zu bewerten. Material und Methoden Zur Untersuchung wurden die Artikulationsgipse dentona® arti-base® 60, piccodent® A 50, AmannGirrbach Artifix® und KerrTM Snow White Plaster No.2 an einen Typ 3 (dentona® dento dur® 110) und 4 Gips (dentona® sockel plaster® GT 160) gegossen. Die zylindrischen Prüfkörper enthielten zentrisch eingegossene Retentionen, die zur Verankerung in einer Universalprüfmaschine dienten. Prüfkörper aus Typ 3 und 4 Gips wurden vor dem Angießen des Artikulationsgipses 48 h getrocknet. Die Messung der Adhäsionskraft (in N) erfolgte mittels Zugversuch, 1 h nach der Erstarrung des Artikulationsgipses. Für jede Kombination wurden 10 Versuche durchgeführt. Die Datenauswertung erfolgte mittels t Test bei unabhängigen Stichproben und Dunnett´s T3 Vergleichstest (α=0,05). Ergebnisse Aus den 80 ermittelten Werten konnte ein Ranking der Gipskombinationen erstellt werden (Max. 1950,77 N, Min. 495,97 N). Es zeigten sich signifikante Unterschiede zwischen den einzelnen Kombinationen aus Modell- und Artikulationsgips. Innerhalb der Kombinationen mit Typ 3 Gips ergaben sich signifikante Unterschiede. Die Gruppen mit Typ 4 Modellgipses unterschieden sich hingegen nicht signifikant. Eine weitere Analyse zeigte bei zwei Artikulationsgipsen einen signifikanten Unterschied zwischen der Verwendung von Typ 3 und 4 Modellgips. Schlussfolgerung Es zeigte sich, dass die neu entwickelte Methode für die Untersuchung der Haftfähigkeit von Artikulationsgipsen geeignet ist. Aneinander gegossene Artikulations- und Modellgipse erreichen unterschiedlich hohe Adhäsionskräfte. Ein Vorteil für die Verwendung des Typ 3 gegenüber dem Typ 4 Modellgips ergab sich nicht. Am besten erschien in unserer Untersuchung die Kombination von dentona® dento dur® 110 und dentona® arti-base® 60.

Lime mortar and plaster have been investigated with the aim to improve the knowledge on how to make them as durable as before the cement technology was developed. The background was the durability problems experienced for newly produced lime plaster on the medieval churches on the island of Gotland, Sweden. In some cases the new lime plaster façades showed severe frost damages after only one winter. Although the lime was burnt and produced according to old local traditions, the lime mortar was still mixed and worked onaccording to methods developed for lime-cement mortar. This often led to a very porous lime plaster with a lime shell in the surface and such a plaster has been shown to be sensitive to frost expansion. Field studies were combined with laboratory studies of thin section specimens. Optical microscopy and scanning electron microscopy have been important analytical methods showing the porosity and the structure of the binder and aggregate materials. The investigations have been carried out on both historic and on newly made reference mortar and plaster. The field studies were carried out mainly on Gotland, using local materials. The influence of the raw materials, i.e. lime, aggregate and blending ratio was investigated. The focus has been on the workability of the fresh mortars as well as the pore structure of the carbonated plaster. The craftsmanship, meaning mixing and application of mortar and working the plaster surface, was studied in order to clarify its final pore structure. The pore structure in a material determines many of its technical properties, such as moisture transportation, compressive strength, permeability and frost resistance. All these properties are closely connected to the durability of the mortar and plaster. The permeability of the plaster has an impact also on the durability of the covered construction materials. Behind low-permeable plasters made with hydraulic binder, examples of extensive damages of rotten wood and leached lime have been shown. The investigations have shown the importance of choosing a mortar adjusted to the building construction. They also showed the importance of choosing a blending ratio adjusted to the specific binder and sand used in order to get a mortar with a suitable pore structure and good durability. It has also shown the importance of knowing when and how to work on the plaster surface in order to obtain a homogenous material that is well receptive for lime wash and has a good frost resistance. The combination of all the investigations has led to a method for reconstructing historic mortar and plaster with good durability.

The study aimed to identify mud brick and mud plaster technology of Hittites by examining some burnt mud brick walls of Shapinuwa Hittite city and to point out repair and conservation needs of those burnt mud brick structures. The walls were documented by mapping the visual decay forms. The bulk density, total porosity, water absorption by capillarity and water vapour permeability were obtained as basic physical properties. The mechanical properties were expressed by the modulus of elasticity and the uniaxial compressive strength. Compositional and mineralogical properties were determined by optical microscopy, XRD, TGA and SEM coupled with EDX, and by XRF analyses. In addition, pozzolanic activity of powdered samples was determined.. The samples studied had low bulk density, high porosity and high water vapour permeability. The Emod values and the UCS values showed that their mechanical properties were comparable with some historic mortars and bricks. The petrographic and mineralogical analyses of burnt materials indicated a mud brick composition containing fine and medium sized siliceous aggregates mainly composed of quartz. The binder was concluded to be composed of kaolinite illite and micritic calcite that indicated the use of ideal soil compositions by Hittites to make lime stabilized mud bricks, in terms of today standards. The temperature during the fire was estimated to be around 700-800 C. The high pozzolanicity of burnt mud bricks and plasters, provided an opportunity to repair the structure using pozzolanic lime mortars to produce good adhesion. The first results of consolidation treatments had shown that the physical and mechanical properties of burnt mud brick can be improved by impregnation with ethylsilicates such as Tegovakon V.