Current global population growth and economic development accelerates the land cover conversion in many parts of the world and compromises the natural environment. However, the impacts of this land cover change on the hydrologic cycle at local to regional scales are poorly understood. The thesis presented here investigates the hydrologic implications of land use conversion in two different settings using two different approaches. The first study focuses in Southeast Asia and the expansion of rubber monocultures in a middle-sized basin. Field measurements suggest rubber has distinct dynamics compared to the area's native vegetation, depleting and exhausting the local water balance more than native vegetation. A phenology based evapotranspiration function is developed and used in a hillslope based hydrologic model to predict the implications of rubber expansion at a basin scale. The second study is centered in the semi-arid southwestern United States. This study challenges the traditional assumption that deforestation increases water yield at regional scales. Observations of water yield in basins affected by a regional piñon pine die-off show a decline in water yield during several years after die-off. These results suggest an increase in landscape sensitivity to vegetation disruption in semi-arid ecosystems as scale increases. Consequences of both studies have important implications for land and water managers in these different ecosystems.

Item lacks publication date - publication date of 1980-1985 indicated by UA Library Catalog and WorldCat.

A steady-state mathematical model for the stripping section of an industrial EPDM rubber production process was developed for a three-tank process, and two four-tank processes. The experiments that were conducted to determine model parameters such as equivalent radius for EPDM particles, as well as solubility and diffusivity parameters for hexane and ENB in EPDM polymer are described. A single-particle multiple-tank model was developed first, and a process model that accounts for the residence-time distribution of crumb particles was developed second. Plant data as well as input data from an existing steady-state model was used to determine estimates for the tuning parameters used in the multiple-particle, multiple-tank model. Using plant data to assess the model’s predictive accuracy, the resulting three-tank and four-tank process B models provide accurate model predictions with a typical error of 0.35 parts per hundred resin (phr) and 0.12 phr. The four-tank process A model provides less-accurate model predictions for residual crumb concentrations in the second tank and has an overall typical error of 1.05 phr. Additional plant data from the three- and four-tank processes would increase the estimability of the parameter values for parameter ranking and estimations steps and thus, yield increased model predictive accuracy. / Thesis (Master, Chemical Engineering) -- Queen's University, 2012-10-23 21:06:05.509

The thesis deals with one major question: is it possible, using one piezoelectric sensor/vibrator, to detect a hard inclusion in a silicone rubber phantom? The question was approached with an open mind and the task was subdivided into three clearly identifiable parts: characterization of the piezoelectric sensor/vibrator (paper I), creating a model of the visco-elastic properties of a tissue-like material (phantom) in contact with the sensor/vibrator (paper II), and to detect the presence of a hard inclusion in the phantom (paper III). All vibrations of the sensor/vibrator and phantom was modeled using a finite element method (FEM). To minimize the computational time and to maximize the FEM model's ability to correctly reproduce the vibrations, a two-dimensional model system consisting of a cylindrical piezoelectric sensor/vibrator, emitting radial elastic waves in to a cylindrical disk-shaped phantom, was chosen. The piezoelectric sensor/vibrator was characterized using a parameter tuning procedure using harmonic overtones. The procedure enables tuning of the electro-elastic parameters of the sensor/vibrator so that the measured and calculated impedance frequency responses match. Silicone rubber was chosen as a phantom to mimic soft tissue. The properties of the phantom was modeled using a fractional derivative visco-elastic model. The hyperelastic effect at the first radial resonance of the sensor vibrator was corrected for by a compensating function. The high frequency complex visco-elastic modulus of the silicone rubber was determined using the transitions of standing Lamb waves in the phantom. The presence of a ring-shaped inclusion in the phantom, of polyamide, was detected using the change of the transitional Lamb wave patterns in the phantom. The tuning of the PZT5A1 sensor/vibrator parameters yielded a match between the calculated and the measured impedance spectra better than 0.54%. The average, complex, elastic modulus of three silicone rubber, Silgel 612, samples were: (0.97 + 0.009i) GPa  at 100 kHz and (0.97 + 0.005i) GPa at 250 kHz. The presence of a polyamide inclusion, PA6GPE, was detected in the phantom using multiple frequency footprints. / Denna avhandling berör frågan: är det möjligt, med en piezoelektrisk sensor/vibrator, att detektera ett hårt objekt inneslutet i en fantom av silikongummi? Frågan närmades utan begränsningar och uppgiften delades upp i tre tydliga delar: karaktäriseringen av den piezoelektriska sensorn/vibratorn (paper I), skapa en modell av det viskoelastiska uppförandet hos ett vävnadsliknande material (fantom) som står i kontakt med sensorn-/vibratorn (paper II) och att detektera förekomsten av ett hårt objekt inneslutet i fantomen (paper III). En finit element modell (FEM) skapades för att beräkna vibrationerna hos sensorn/vibratorn och fantomen. För att minimera beräkningstiden och maximera modellens förmåga att återge vibrationer på ett korrekt sätt, så skapades ett tvådimensionellt modellsystem bestående av en cylindrisk piezoelektrisk sensor/vibrator i kontakt med en cylindrisk fantom av silikongummi. Sensorn/vibratorn skickar radiella elastiska vågor in i fantomen. Den piezoelektriska sensorn/vibratorn karakteriserades med hjälp av en procedur som anpassar parametervärden med hjälp av övertoner. Proceduren möjliggör en justering av parametervärdena så att uppmätta och beräknade impedansspektra överensstämmer. En 'fractional derivative' modell av de viskoelastiska egenskaperna hos silikongummit skapades. De hyperelastiska egenskaperna vid första radiella resonansen blev kompenserade med hjälp av en sigmoidformad funktion. Den komplexa viskoelastiska modulen bestämdes för höga frekvenser med hjälp av transitioner hos stående Lambvågor i fantomen. Närvaron av ett hårt ringformat objekt i fantomen detekterades med hjälp av förändringar i mönstret hos de stående Lambvågorna. Justeringen av de piezoelektriska parametrarna hos elementet PZT5A1 gav som mest en skillnad på 0.54% mellan uppmätta och beräknade impedansspektra. Medelvärdet hos tre prov av silikongummit Silgel 612 av den komplexa elastiska modulen uppmättes till (0.97 + 0.009i) GPa  vid 100 kHz och (0.97 + 0.005i) GPa vid 250 kHz. Närvaron av ett hårt objekt, gjort av polyaramid (PA6GPE), detekterades i fantomen med hjälp av multifrekvensiella fotavtryck.

No description available.

Orientador: Aldo Eloizo Job / Banca: Rodrigo Fernando Bianchi / Banca: Dalita Gomes Silva Moraes Cavalcante / Banca: Antonio Hernandes Chaves Neto / Banca: Felipe Silva Bellucci / Resumo: Filmes de borracha natural (BN), fabricadas a partir do látex da seringueira Hevea braziliensis, foram utilizadas neste trabalho como substratos ativos para a obtenção de nanopartículas de prata (AgNPs) e como substrato inativo para nanopartículas semi-condutoras fluorescentes, os pontos quânticos ou quantum dots (QDs). O filme de BN agiu como um reator para a síntese das AgNPs, sendo ele o agende redutor, estabilizador e substratos destas. A síntese pode ter ocorrido devido a interação de amidas, provenientes das proteínas presentes no látex, com os íons prata, provenientes da dissociação do nitrato de prata (AgNO3) em água, dando origem à um processo de síntese verde de nanopartículas (NP). O processo de síntese foi realizado por imersão dos filmes de BN na solução de AgNO3 por diferentes tempos, sendo os filmes obtidos após este processo denominados filmes de BN/Ag com distintas concentrações de AgNPs, sendo estas com formato esférico e tamanho variando entre 25 nm a 60 nm. Estudos de citotoxicidade e genotoxicidade in vitro, foram realizados utilizando as linhagens celulares CCD 1059 sk (fibroblasto humano normal) e CHO K1 (fibroblasto de ovário de hamster) e a avaliação dos resultados destes ensaios demonstram que os filmes, tanto de BN e de BN/Ag, não geram danos ao metabolismo celular para as linhagens estudadas e também não se observou dano ao DNA de tais células. Ainda neste trabalho foi obtido filmes flexíveis fluorescentes devido a mistura líquido-líquido do látex ... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: Natural rubber films (NR), made from latex of Hevea brasiliensis, were used in this study as active substrates to obtain silver nanoparticles (AgNPs) and as inactive substrate for fluorescent semi-conductor nanoparticles, quantum dots (QDs). The NR film plays as a reactor, reduce agent, stabilizer and substrate for AgNPs synthesis. The synthesis may be due to interaction amides derived from proteins present in latex, with the silver ions from the dissociation of silver nitrate (AgNO3) in water giving rise to a process of green synthesis of nanoparticles (NP). The synthesis process was carried out by immersing the BN film on AgNO3 solution for different times, and the films obtained after this process called BN films/Ag with different concentrations of AgNPS, which are spherical shape and size between 25 nm 60 nm. Cytotoxicity and genotoxicity studies in vitro were performed using the cell line CCD 1059 sk (normal human fibroblast) and CHO-K1 (hamster ovary fibroblast) the results of these assays demonstrate that films, BN and BN/Ag, do not generate damage to cell linage metabolism and also there was no damage to the DNA of these cells. Still, in this work, was obtained flexible fluorescent films from liquid-liquid mixture between the natrual rubber latex and QDs solution; after the drying process there was obtained a fluorescent flexible film and those emissions can be observed for different wavelengths in the visible spectrum while the samples in the solid state, exhibit sam... (Complete abstract click electronic access below) / Doutor

Informationen om att det bränns ull i mängder samtidigt som vi importerar ull talar sitt tydligaspråk att något behöver göras. Ull som är ett hållbart och 100% förnybart material med bådehistoriska och fantastiska egenskaper, vilket gör att det är ett enormt resursslöseri att brännaull som om det vore skräp. Det finns många eldsjälar inom fårbranchen som arbetar för atthitta lösningar för dessa problem. Ullklassificering, att ta fram en nationell agenda överullhantering och försök att öka intresset för ull i allmänhet står på agendan. Utifrån ett hållbarhetsperspektiv såväl som ett personligt intresse och utifrån mina år somstylist har jag undersökt ullens sinnliga egenskaper för att hitta nya materialupplevelser i ettav världens äldsta textila material. Klimatfrågan som är högst aktuell, vilket vi alla på ett ellerannat sätt måste förhålla oss till, samt mitt mål att göra min forskning tillgänglig för alla, göratt mitt arbete har relevans utifrån ett hållbart, samhällsmässigt och kunskapsmässigtperspektiv. Utifrån en materialdriven design, där materialets mening står för att väva in denkänslomässiga kopplingen svensk ull, vill jag med konstnärlig ansats ta mig an arbetet i attutforska, utvärdera och ifrågasätta mig själv. Basen i hela mitt arbete är den materialdrivnaprocessen där jag varvar material och användartester för att bidra med nyamaterialupplevelser av ull. Jag hoppas att mitt arbete gör att vi ser med nya ögon på ull ochatt våra associationer till svensk ull inte enbart ses som en stickad tjocktröja eller ett parlovikkavantar från en gången tid. Jag vill vidga perspektiv och inspirera till att se möjligheter iden materialskatt vi har runt hörnet. / The information that wool is burned in quantities while we are importing wool speaks its clearlanguage, something needs to be done. Wool, which is a durable and 100% renewablematerial with both historical connections as well as fantastic properties, is a huge waste ofresources to burn as if it were rubbish. From a sustainability perspective as well as a personal interest, based on my years as astylist, I have investigated the sensual properties of the wool to find new materialexperiences in one of the world's oldest textile materials. The climate issue that is mostup-to-date, which we all have to relate to in one way or another, and that I want to make myresearch available to everyone, means that my work is relevant from a sustainabilityperspective. I have worked from a material-driven design, where the meaning of the material has beenimportant in order to weave the emotional connection to a material. With an artisticapproach, I wanted to take on my work in exploring, evaluating and questioning myself andmy work in a material-driven process, in which I turn materials and user tests to contributewith new material experiences of wool. I hope that my work contributes to seeing Swedishwool with new eyes. With new associations and perspectives. To see opportunities insteadof impossibilities.

A thesis submitted to the Faculty of Engineering and the Built Environment, University of the Witwatersrand, Johannesburg, in fulfilment of the requirements for the degree of Doctor of Philosophy. Johannesburg 10th of October 2016 / Thermal pyrolysis is one of the viable technologies suitable for the management of organic solid waste, which has become a global challenge over the years. This is due to the non-biodegradability of these materials and their continuous usage across all segments of man’s daily activities. Effectiveness of the method is in converting these materials under controlled process conditions, that enable the optimization of the fraction of interest, such as the liquid fraction also referred to as pyrolytic oil with a near zero pollution effect on the environment. The main setback in the production of the liquid fraction include low yield, presence of sulphur and other aromatic compounds which have been linked to environmental pollution and health complications. This study focuses on improving the liquid fraction yield and composition obtainable from pyrolysis process. Latex natural rubber (obtained from Hevea Brasiliensis) was pyrolysed and its products compared with that of the used tyres. The production of pyrolytic oil from used tyres and natural rubber was performed using thermal and catalytic pyrolysis processes. The operating temperature range of 375 to 750 oC (at an interval of 75 oC) at a heating rate of 15oC/min and feed material particle sizes of 2, 4, 6, 8 and 10 mm were used. In addition, Zeolite NaY was synthesized from Lawani Benin River Kaolin (LBK) at a synthesis time and temperature of 9 h and 100 oC respectively, using hydrothermal synthesis method, and used for catalytic pyrolysis. The chemical characterisation revealed pyrolytic oil composition to be a complex mixture of aliphatic, aromatics, polycyclic aromatic hydrocarbons and other oxygen, nitrogen, sulphur and chlorinated compounds in small proportions. The non-catalysed and catalysed pyrolysis using natural rubber resulted in pyrolytic oil with 80 and 66% of aliphatic, 12 and 15% aromatic (with polycyclic aromatic hydrocarbons concentration of 2 and 1%). The non-catalysed and catalysed pyrolysis using used tyres yielded pyrolytic oil with 42 and 32% of aliphatic, 34 and 39% aromatic (with polycyclic aromatic hydrocarbons concentrations of 18 and 23%). The kinetics of the thermal degradation with the aid of a thermogravimetry and differential thermogravimetry analyzer was performed over a temperature range of 30 to 800 oC at a heating rate of 15, 20 and 30oC/min. Results showed that natural rubber displayed higher activation energy than used tyres, with respect to the heating rates. This is an indication that natural rubber is more difficult to thermally decompose than used tyres. The distillation temperature of the distillates was within the temperature range of the conventional petrol and diesel. The composition of the distillates revealed carbon chain length of C5-C30 with majority being C8 – C10. A spark ignition generator engine was used to perform the combustion tests for the various pyrolytic oil distillates and petrol blended in the ratio 0, 5, 10, 15 and 20% successfully without engine modification. For the fuel consumption with respect to generator run time, it was observed that an optimum of 20% natural rubber pyrolytic oil distillates (NRPD)-Petrol blend gave comparative fuel consumption behavior with that of commercial petrol. Furthermore, the 20% NRPD distillates gave optimum fuel consumption and power. Hence, a significant yield improvement and combustion performance were observed for the pyrolytic oil derived from natural rubber than that of used tyres. Further treatment of the pyrolytic oil distillates could pave the way for effective use of the oil as chemical feedstock for industries, or as substitutes for fossil fuel. It was also requisite to develop a mathematical model which adopts thermogravimetry analyser (TGA) as a dynamic apparatus to predict weight change of a material as it degrades with time at a fixed temperature. The proposed models were in three consecutive phases which were classified into three time zones 0 ≤ t ≤ t1, t1 ≤ t ≤ t2 and t ≤ t2. The general model equation for the first phase of degradation was 2 0 1 2 0 ( ) t T w t w e   , while the second phase model was and at the third phase, it is assumed that the limit of weight loss (in the second phase equation) as t tends to ∞ gives a value k , at which change in weight loss with time is negligible. The proposed model was used to plot graph of weight loss versus time at different fixed temperature which fitted well with the experimental TGA and had a characteristic pattern fitted closely to the second phase degradation of the fixed bed reactor. / MT2017

A decomposição natural da borracha é muito lenta, devido às suas estruturas vulcanizadas serem extremamente reticuladas formando uma rede tridimensional, tornando o reprocessamento desse material extremamente difícil. O presente trabalho tem como principal objetivo o estudo da aplicação da radiação gama como forma de desvulcanização para a reciclagem/reaproveitamento. Foi avaliada a interação de elastômeros com a radiação ionizante de fonte gama investigando-se as alterações nas propriedades físico-químicas dos materiais. Foram utilizadas formulações de borracha NBR (copolímero de Acrilonitrila-Butadieno) e EPDM (terpolímero etileno-propileno-dieno), provenientes da indústria de borracha, reticuladas por mistura convencional à base de enxofre. Foram preparados master-batch com pó de borracha (refugo industrial) e borracha virgem. O material processado (master-batch) foi irradiado em fonte de 60Co nas doses de 50, 100, 150 kGy e taxa de dose de 5 kGy h-1, à temperatura ambiente. O material irradiado foi incorporado nas formulações clássicas à base de enxofre. As formulações foram caracterizadas por: espectroscopia no infravermelho (FTIR), análise térmica (TG e DTG), tensão na ruptura, alongamento na ruptura, dureza, resistência à abrasão, reometria e inchamento. Os resultados mostraram uma predominância de cisão de cadeia na dose de 50 kGy para a borracha EPDM. Para a borracha nitrílica foi observada a predominância de cisão de cadeia na dose de 100 kGy. Estes resultados mostram a possibilidade do uso da radiação gama para o reaproveitamento/reciclagem das borrachas EPDM e nitrílica. / The natural decomposition of rubber is a very slow process due to its three-dimensional network formed by vulcanized crosslinked structures becoming extremely difficult to reprocess this material. The present work aims to study the application of gamma irradiation as devulcanization process for material reuse/recycling. The interactions of elastomers with ionizing radiation of a gamma source were investigated and the changes in physicochemical properties of the materials were evaluated. Formulations of NBR (acrylonitrile - butadiene) and EPDM (ethylene - propylene - diene terpolymer) from the rubber industry were crosslinked by conventional sulfur-based mixing. Master - batch was processed with rubber powder (industrial waste) and virgin rubber. The raw material (master batch) was irradiated in 60Co source at doses of 50, 100, 150 kGy and dose rate of 5 kGy h-1 at room temperature. The irradiated material was incorporated in classical sulfur-based formulations. The formulations were characterized by: infrared spectroscopy (FTIR), thermal analysis (TG and DTG), tensile strength, elongation at break, hardness, abrasion resistance, rheometry and swelling. The results showed a predominance of chain scission at a dose of 50 kGy for EPDM rubber. For nitrile predominance of chain scission was observed at a dose of 100 kGy. These results show the possibility of the use of gamma radiation for the reuse/recycling of EPDM and nitrile rubbers.

Neste trabalho procura-se desenvolver reflexões acerca das mudanças nos modos de vida que os seringueiros de Xapuri/AC vêm experimentando desde o assassinato de Chico Mendes, em 1988. Neste sentido, as atenções e energias do estudo foram concentradas na tentativa de perceber, principalmente a partir de relatos coletados com moradores do Projeto de Assentamento Agroextrativista Cachoeira e Reserva Extrativista Chico Mendes, os novos temores, as novas experiências e os novos desafios, entre outras histórias experimentadas pelos seringueiros residentes nos locais pesquisados. Para isso, procurou-se estabelecer um diálogo com as experiências desses sujeitos sociais, objetivando traduzir, por meio de relatos colhidos, in loco, as vozes, os rostos e as vivências humanas na cena do estudo. A História Oral foi a estratégia metodológica principal utilizada para a obtenção das fontes. Entretanto, também fontes escritas foram utilizadas. A análise e o diálogo com as fontes apontam que as principais modificações no viver dos sujeitos pesquisados aconteceram, principalmente, após a chegada ao poder estadual de um grupo político denominado Frente Popular do Acre. Esse Governo, que se autodenominou Governo da Floresta, realizou investimentos patrocinados por organizações internacionais que trouxeram mudanças significativas no modus vivendi das pessoas do interior das matas xapurienses. Essas mudanças melhoraram a vida dos sujeitos, mas também trouxeram problemas, riscos e prejuízos. A possibilidade do desaparecimento dos seringueiros, deixando o território limpo para outras explorações, constituiu-se em uma das importantes questões que a pesquisa evidenciou e suscita no meio social da floresta xapuriense / This work seeks to develop reflections on the changes in the lifestyles the rubber tappers from Xapuri/AC have been experiencing since the murder of Chico Mendes, in 1988. In this sense, the attention and the energy of the study were concentrated on trying to perceive, mainly from the reports of the dwellers of the Cachoeira Extractive Settlement Project and the Chico Mendes Extractive Reserve, the new fears, the new experiences and the new challenges, among other stories the rubber tappers residing in the surveyed areas have gone through. For this purpose, a dialogue was established with the experiences of those social subjects, aiming to translate, through the reports collected, in loco, the voices, the faces and the living experiences in the scene of the study. The Oral History was the main methodological estrategy used to obtain the sources. However, written sources were also used. The analysis and the dialogue with the sources indicate that the major changes in the living of the studied subjects happened, primarily, after a political group called Popular Front of Acre came to power state. That Governance, which called itself Government of the Forest, sponsored investments held by international organizations which brought significant changes to the modus vivendi of the people from the interior of Xapuris forest. Those changes have improved the life of the subjects, but they also brought problems, risks and damages. The possibility of disappearance of the rubber tappers, leaving the territory clean for other holdings, constituted itself into one of the important questions that the survey evidenced and raises in the social environment of Xapuris forest