Thesis (MScFor (Forest and Wood Science))--University of Stellenbosch, 2006. / Producing high quality end products, rather than focusing on volume production, is slowly but surely becoming the main driving force in the wood processing industry of South Africa. Drying defects such as surface checks and discolouration by yellow stain and kiln brown stain are major factors in softwood timber downgrades when selecting furniture grade timber. Previous efforts to control these defects have focused on schedule adaptation, but as the industry is still mainly concerned with volume production, and because of the varying lumber price, longer schedules to control these drying defects have not yet been that attractive for the larger sawmills. In ongoing research in this laboratory, a dip treatment of freshly sawn softwood boards in an aqueous solution containing a surfactant called sodium lauryl sulphate (SLS) was used to try to influence the mechanism involved in the development of these stains. Further, complementary research is reported in this study. Firstly, the possibility of using SLS solutions to control surface mould development and bluestain was investigated. Results showed that SLS did control the development of blue stain and mould growth in open-stacked boards for up to three weeks, using concentrations as low as 0.1%, and up to two weeks in closed-stacked timber when using concentrations of 0.2%. Secondly, it was investigated whether SLS treatment would have a detrimental effect on downstream product quality; in particular, kiln dried boards and glued components for furniture manufacturing. Since SLS influenced fluid water flow during kiln drying, the treatment could have exacerbated the occurrence of surface checking due to altered moisture distribution profiles. Results of this investigation showed that the SLS treatment did not result in increased surface checking. Thirdly, as furniture quality timber treated with SLS would be glued, (and also finished with surface coatings), it was further considered important to determine if SLS treatment influenced adhesion properties of wood surfaces. Based on shear test results, it was established that SLS did not influence the adhesion properties of wood when glued with two most commonly used glues in the furniture industry i.e. polyvinyl acetate (PVAc) and urea formaldehyde (UF).

Resumo: Foram realizados 3 experimentos com o objetivo de avaliar as características físicas e químicas, sensoriais e microbiológicas de ovos de casca branca e vermelha, higienizados ou não, e armazenados em diferentes condições de embalagens sob temperatura ambiente. 1.800 ovos de casca branca e 1.800 de casca vermelha foram embalados em três condições de embalagens (filme PVC, vácuo parcial e vácuo parcial com sachês sequestrantes de O2) e armazenados durante quatro períodos (7, 14, 21 e 28 dias). Exceto para as análises microbiológicas de quantificação de bolores e leveduras na casca dos ovos, foi utilizado um delineamento inteiramente casualizado em esquema fatorial 3x2x4+1 (condições de embalagem, higienização ou não, e períodos de armazenamento + testemunha - ovos frescos), com 4 repetições. As médias obtidas foram comparadas pelo teste de Tukey a 5 % de significância. Concluiuse que a qualidade interna dos ovos decresce com o tempo de estocagem de forma mais acentuada nos ovos embalados em filme plástico, já que a condição de vácuo preservou algumas características dos mesmos. E com a higienização, as condições de armazenamento dos ovos em filme de PVC devem ser melhoradas, pois a queda da qualidade interna destes foi a mais afetada. Na análise sensorial, os ovos embalados em filme de PVC foram os que mostraram melhores aceitações em todos os atributos avaliados, independente de terem sido higienizados ou não. Ovos embalados em condição de vácuo com sachê sequestrante de gás oxigênio em relação à contaminação microbiana de suas cascas foram semelhantes aos ovos embalados em filme plástico, que é a forma comercialmente empregada / Abstract: Three studies were conducted with the aim of evaluating the physical and chemical characteristics, sensory and microbiological of white and redshelled eggs, sanitized or not, stored under different packaging conditions at room temperature. 1.800 white shelled and 1.800 red shelled eggs were packed in three conditions of packaging (PVC film, partial vacuum and partial vacuum with gas sachets O2 absorbers) and stored for four periods (7, 14, 21 and 28 days). Except for microbiologically analysis of quantification of yeasts and molds in eggshell, it was used a completely randomized experimental design in a 3x2x4+1 factorial arrangement (three packaging conditions, sanitized or not, storage period, and control - fresh eggs), with four repetitions. The averages were compared by Tukey test at 5% significance level. It can be concluded that the internal egg quality decreases with storage time sharper in the eggs packed in PVC film, because vacuum has preserved some features of them. With sanitation, the storage conditions of eggs in PVC film should be improved because its internal quality decrease was the most affected. At sensory analyzes the eggs packed in PVC film showed the best acceptances in all attributes, be sanitized or not. And on partial vacuum with oxygen gas absorbers condition had their shells with similar microbial contamination of eggs packaged in plastic film, which is the used commercially / Orientadora: Hirasilva Borba / Coorientadora: Luciana Miyagusku / Banca: Nadja Susana Mogyca Leandro / Banca: Raphael Lucio Andreatti Filho / Banca: Vera Maria Barbosa de Moraes / Banca: Maria Regina Barbieri de Carvalho / Doutor

Made available in DSpace on 2014-10-09T12:41:52Z (GMT). No. of bitstreams: 0 / Made available in DSpace on 2014-10-09T14:08:05Z (GMT). No. of bitstreams: 0 / Dissertação (Mestrado) / IPEN/D / Instituto de Pesquisas Energeticas e Nucleares - IPEN-CNEN/SP

Made available in DSpace on 2016-12-08T17:19:20Z (GMT). No. of bitstreams: 1 Resumo Vanessa Mais do Amaral.pdf: 96205 bytes, checksum: 79515eecc52116cd10d77e7e7c8fc625 (MD5) Previous issue date: 2012-08-24 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / The study of the packing of the green sand molds has become increasingly important over the recent years due to the demand for castings of greater dimensional accuracy. Another reason is the growth of products with complex geometry, increasing the need for molds with higher degree of compression across the model profile. In this work, the packing was quantified by measuring the resistance (N / cm ²) of molds, made with different molding technologies. The resistance values of molds manufactured in a high pressure, without air flow molding machine and a jolt squeeze molding machine were compared, using a model of the same geometry. Another experiment tried to quantify the impact of the compaction parameters such as pressure, time of compression and time of air flow, over the resistance measured on a mold made in an air flow squeeze molding machine. Another goal was to measure the influence of molding sand on the packing, through the flowability tests TNO and Orlov. It has been found that castings made on the high pressure machine without air flow, have greater resistance on regions of easy compression, but complex geometry models tend to be more likely to porosities in the mold when compared to jolt squeeze machines. It was also observed that the pre-compression by air flow increases the packing in the most critical regions of the mold. Regarding the method TNO, it is possible to verify that the flowability decreases with increasing compactability of the molding sand, but has no correlation with the variations in the bentonite level. When it comes to the Orlov flowability, it is reduced when it is applyed mixtures with high compactibility, high levels of natural sodium bentonite, finer sand and longer mixing time. / O estudo do adensamento dos moldes em areia a verde tornou-se cada vez mais importante ao longo dos últimos anos em função da procura por peças fundidas de menor variação dimensional. Outro motivo é o crescimento de produtos com geometria complexa aumentando a necessidade de obter moldes com alto grau de compactação em todo o perfil do modelo. Neste trabalho, o adensamento foi quantificado através de medições da resistência (N/cm²) dos moldes confeccionados em diferentes tecnologias de moldagem. Foram confrontados os valores de resistência dos moldes confeccionados em uma máquina de alta pressão sem fluxo de ar e uma máquina de vibração compressão utilizando um modelo de mesma geometria. Outro experimento procurou quantificar o impacto dos parâmetros de compactação como a pressão, tempo de compressão e o tempo de fluxo de ar sobre a resistência medida em moldes confeccionados em uma máquina de alta pressão com fluxo de ar. Objetivou-se também medir a influência da areia de moldagem sobre o adensamento através dos ensaios de fluxibilidade TNO e Orlov. Verificou-se que os moldes confeccionados na máquina de alta pressão sem fluxo de ar possuem maior resistência nas regiões de fácil compactação, mas que em modelos de geometria complexa tendem a apresentar maior tendência às porosidades no molde quando comparado às máquinas de vibração - compressão. Observou-se também que a pré-compactação por fluxo de ar aumenta significativamente o adensamento nas regiões mais críticas do molde. Com relação ao método TNO, é possível verificar que a fluxibilidade diminui com o aumento da compactabilidade da areia de moldagem, mas não possui correlação com as variações no teor de bentonita. Porém a fluxibilidade Orlov é reduzida quando se aplica misturas contendo alta compactabilidade, alto teor de bentonita sódica natural, areias mais finas e maior tempo de mistura.

As estruturas de concreto são moldadas em formas tratadas com desmoldantes e sua presença dificulta a adesão da argamassa fresca, com posterior descolamento no estado endurecido. Este estudo tem por objetivo explorar o potencial de uso de agentes retardadores em substituição aos desmoldantes convencionais na moldagem de concreto para obtenção de superfícies com maior capacidade de ancoragem das argamassas. A viabilidade do uso de agentes retardadores foi verificada determinando-se de modo comparativo a resistência de aderência à tração da argamassa e do chapisco aplicados sobre corpos de prova de concreto moldados em formas de madeira plastificada tratadas com agente retardador e com desmoldante convencional. O ensaio de aderência mostrou que a utilização de agentes retardadores possibilita maior facilidade para a remoção da camada superficial do concreto, resultando em aumento de rugosidade e absorção superficial, permitindo maior resistência de aderência da argamassa e chapisco. Posteriormente, foram coletados agentes retardadores do mercado e avaliados: desempenho na aplicação sobre as formas, impacto dos produtos na saúde do trabalhador e no meio ambiente, e o efeito retardador na hidratação do cimento. Também foram avaliados quanto: a aplicabilidade dos produtos e sua influência no preparo da superfície para o recebimento da argamassa quando tratadas com produtos retardadores e convencionais em três tipos de formas. O estudo mostrou que o uso de agente retardador pode ser uma técnica viável para reduzir os problemas de descolamento do revestimento aplicado sobre superfícies de concreto. Através dos ensaios específicos desenvolvidos e adaptados para esta pesquisa, foi possível identificar que existem diferenças de comportamentos entre os produtos, sendo eles convencionais ou retardadores, e que os tipos de forma influenciam nestes comportamentos. Foi verificado também que as formas mais simples e com custos menores podem ser mais apropriadas para utilização destes produtos. / The concrete structures are cast in molds treated with a release agent (demolding product), and its presence hinders the mortars initial adhesion in the plastic state, as well as the bond strength after hardening. The study aims is to explore the potential use of retarding agents to replace conventional release agents in the concrete formwork. The technical viability of using a retarding agent was verified by comparing the tensile bond strength of rendering mortars applied on concrete surfaces cast with a conventional release agent and on concrete surfaces cast with a retarding release agent. The results showed that, through the use of retarding products, the removal of the concrete surface layer was possible by increasing the surface roughness, the surface water absorption and the tensile bond strength of the mortar to this concrete. Performance tests were also done with retarding products commercially available in the Brazilian market to verify the behavior of such products during application on molds, their impact on workers health and on the environment, and the retarding effect in cement hydration. It was also evaluated the applicability of these products and their influence on surface preparation to receive mortar when treated with retarding and conventional products, in three types of molds. Retarding products showed to be a viable technique for reducing the detachment problems of rendering mortars applied on concrete surfaces. Through the specific tests developed and adapted for this study, it was observed that there are differences in behavior between the conventional or retarding products, and also observed how these types of molds can influence the performance of the products. It was also observed that the simplest molds with lower cost can be more suitable in this application.

The purpose of this paper is to present a comparative study of marine bacteria, molds and actinomycetes in regard to their ability to degrade certain pure and mixed complex compounds possibly occurring in the lagoon waste traps of the Texas Gulf Coast. This comparison was made using a differential oxygen uptake as the index of specific compound utilization.

This thesis describes the optimalization of technological parameters during commissioning of injection mold manufacturing. In the introduction, there is general literary studies of plastics, injection molds, injection holding machine, injection holding technology and their effect on quality. The practical part includes an analysis of current state, calculation of injection parameters, moldflow analysis and sampling on the machine. Finally, there is choice of optimal injection holding parameters, design of workplace and technical-economic evaluation.

Fungi represent one of the most diverse and abundant eukaryotes on earth. The interplay between mold exposure and the host immune system is still not fully elucidated. Literature research focusing on up-to-date publications is providing a heterogenous picture of evidence and opinions regarding the role of mold and mycotoxins in the development of immune diseases. While the induction of allergic immune responses by molds is generally acknowledged, other direct health effects like the toxic mold syndrome are controversially discussed. However, recent observations indicate a particular importance of mold/mycotoxin exposure in individuals with pre-existing dysregulation of the immune system, due to exacerbation of underlying pathophysiology including allergic and non-allergic chronic inflammatory diseases, autoimmune disorders, and even human immunodeficiency virus (HIV) disease progression. In this review, we focus on the impact of mycotoxins regarding their impact on disease progression in pre-existing immune dysregulation. This is complemented by experimental in vivo and in vitro findings to present cellular and molecular modes of action. Furthermore, we discuss hypothetical mechanisms of action, where evidence is missing since much remains to be discovered.

No description available.

Thesis (MSc)--University of Stellenbosch, 2004. / ENGLISH ABSTRACT: Numerous workers studied the impact of pollutants and agricultural chemicals, containing heavy metals such as copper (Cu), on soil microbes. It was found that elevated soil Cu levels do have a detrimental effect on soil bacterial populations however the filamentous fungi seemed to be less affected. Most of these studies were conducted in soils containing already relatively high Cu levels and the effect of this heavy metal on the nonfilamentous fungi (i.e. yeasts) was never investigated. The aim of this study was therefore to determine the impact of elevated Cu levels on filamentous fungi and yeasts occurring in soils containing relatively low natural Cu levels. A synthetic selective medium containing glucose as carbon source, thymine as nitrogen source, vitamins, minerals and chloramphenicol as anti-bacterial agent (TMV-agar), was used to enumerate ascomycetous and basidiomycetous Cu resistant yeasts in a sample of virgin soil containing ~ 2ppm Cu. Media that were used to enumerate Cu resistant filamentous fungi were malt extract agar, malt extract agar with streptomycin sulfate, maltyeast- extract-peptone agar with chloramphenicol and streptomycin sulfate, benomyl–dichloran-streptomycin medium for the enumeration of hymenomycetous fungi and two selective media for the isolation of mucoralean fungi. Cu resistant fungi able to grow on all of the above mentioned solid media supplemented with 32 ppm Cu occurred in the soil sample. To obtain an indication of the level of Cu tolerance of fungi present in this soil sample, a number of fungal isolates were screened for the ability to grow on a series of agar plates, prepared from glucose-glutamate-yeast extract agar, containing increasing concentrations of Cu. It was found that filamentous fungi and yeasts that were able to grow on this agar medium containing up to 100 ppm Cu were present in the soil. A series of soil microcosms was subsequently prepared from the soil sample by experimentally contaminating the soil with increasing amounts of copper oxychloride, were after fungal populations in the microcosms, including Cu resistant fungi, were monitored using plate counts. At the end of the incubation period, after 245 days, fungal biomass in the microcosms was compared by determining the concentrations of the fungal sterol, ergosterol, inthe soil. Generally, Cu had little impact on the numbers of filamentous fungal colony forming units on the plates, as well as on the ergosterol content of the soil. The numbers of filamentous fungi in the soil, including the Mucorales and hymenomycetes, seemed to be less affected by the addition of copper oxychloride than the numbers of soil yeasts able to grow on TMV-agar. The focus of the next chapter was on the response of yeasts in different soils to elevated levels of Cu in the soil. TMV-agar was used to enumerate yeasts in soil microcosms prepared from four different soil samples, which were experimentally treated with copper oxychloride resulting in Cu concentrations of up to 1000 ppm. The selective medium supplemented with 32 ppm Cu was used to enumerate Cu resistant yeasts in the microcosms. The results showed that the addition of Cu at concentrations ≥ ~1000 ppm did not have a significant effect on total yeast numbers in the soil. Furthermore, it was found that Cu resistant yeasts were present in all the soil samples regardless of the amount of Cu that the soil was challenged with. At the end of the incubation period, yeasts in the microcosms with zero and ~1000 ppm additional Cu were enumerated, isolated and identified using sequence analyses of the D1/D2 600-650bp region of the large subunit of ribosomal DNA. Hymenomycetous species dominated in the control soil, while higher numbers of the urediniomycetous species were found in the soil that received Cu. These observations suggest that urediniomycetous yeasts may play an important role in re-establishing overall microbial activity in soils following perturbations such as the addition of Cu-based fungicides. / AFRIKAANSE OPSOMMING: Vele navorsers het al die impak van besoedelingstowwe en landbouchemikalieë wat swaarmetale soos koper (Cu) bevat, op grond-mikrobes bestudeer. Dit is gevind dat verhoogde Cu vlakke ‘n nadelige effek het op grond-bakteriese populasies, maar dat die filamentagtige fungi geneig is om minder geaffekteer te word. Meeste van hierdie studies is gedoen met gronde wat alreeds relatief hoë Cu vlakke bevat het en die effek van hierdie swaarmetaal op die nie-filamentagtige fungi (d.i. giste) is nooit ondersoek nie. Die doel van hierdie studie was dus om die impak van verhoogde Cu vlakke op filamentagtige fungi en giste in gronde, wat natuurlike lae vlakke van Cu bevat, te bepaal. ‘n Sintetiese selektiewe medium wat glukose as koolstofbron, timien as stikstofbron, vitamiene, minerale asook chloramfenikol as anti-bakteriese agent bevat (TMV-agar), is gebruik om askomisete en basidiomisete Cu weerstandbiedende giste in ‘n monster ongeskonde grond, bevattende ~ 2dpm Cu, te tel. Media wat gebruik is om Cu weerstandbiedende filamentagtige fungi te tel, was mout-ekstrak agar, moutekstrak agar met streptomisiensulfaat, benomiel-dichloran-streptomisien medium vir die tel van hiemenomiseetagtige fungi en twee media vir die isolasie van mukoraliese fungi. Cu-weerstandbiedende fungi wat op al die bogenoemde media, aangevul met 32 dpm Cu, kon groei, het in die grondmonster voorgekom. Om die mate van Cu-weerstandbiedendheid van fungi wat in die grondmonster voorkom, te bepaal, is ‘n getal fungus-isolate op agarplate, voorberei met glukose-glutamaat-gis ekstrak agar, bevattende verhoogde konsentrasies Cu, nagegaan. Daar is gevind dat daar filamentagtige fungi en giste in die grond voorkom wat die vermoë het om op media bevattende 100 dpm Cu te groei. ‘n Reeks grond mikrokosmosse is dus voorberei vanaf die grondmonster deur om dit eksperimenteel te kontamineer met verhoogde hoeveelhede koper oksichloried, waarna die fungus-populasies asook die Cu-weerstandbiedende fungi in die mikrokosmos gemoniteer is deur middel van plaattellings. Aan die einde van die inkubasie periode, 245 dae, is die fungus biomassa in al die mikrokosmosse bereken deur die konsentrasie van die fungus sterool ergosterool te bepaal en dit met mekaar te vergelyk. Oor die algemeen het Cu min impak ten opsigte van diegetal filamentagtige fungi kolonie vormende eenhede die plate, asook op die ergosterool inhoud van die grond gehad. Dit wil voorkom of die getal filamentagtige fungi in die grond, insluitende die Mucorales en die hymenomisete, minder geaffekteer is deur die toediening van koperoksichloried as die aantal grondgiste wat op die TMV-agar kan groei. Die fokus van die volgende hoofstuk was dus op die reaksie wat giste in verskillende grondtipes gehad het op verhoogde Cu in die grond. TMV-agar is gebruik om die getal giste te bepaal in die grond mikrokosmosse van die vier verskillende grondmonsters, wat voorberei is deur om dit eksperimenteel met koper oksikloried te kontamineer tot en met Cu konsentrasies van 1000 dpm. Die selektiewe medium wat gesupplementeer is met 32 dpm Cu, is gebruik om Cu weerstandbiedende giste in die mikrokosmosse te bepaal. Die resultate toon dat die toevoeging van Cu by konsentrasies ≥ ~1000 dpm nie enige beduidende effek op die totale gis getalle gehad het nie. Daar is ook gevind dat daar Cu weerstandbiedende giste in die grond monsters voorkom gekom het ten spyte van die hoeveelheid Cu wat tot die grond toegevoeg is. Aan die einde van die inkubasie periode is die giste wat die die mikrokosmosse bevattende nul en ~1000 dpm Cu getel, geïsoleer en geïdentifiseer deur gebruik te maak van DNA volgorde bepaling van die D1/D2 600-650 bp areas geleë in die groter subeenheid van die ribosonale DNA. Hymenomisete spesies het in die grond kontrole gedomineer, terwyl hoër getalle uredinomisete spesies in die grond met addisionele Cu gevind is. Die resultate dui daarop dat uredinomisete giste dalk ‘n belangrike rol kan speel in die hervestiging van die oorwegende mikrobiese aktiwiteit in grond na skoktoestande soos die aanwending van Cu-gebaseerde fungisiede.