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1
MORÈ, NICCOLÒ. « Lipopolysaccharide transport and peptidoglycan remodeling : two related processes in Escherichia coli ». Doctoral thesis, Università degli Studi di Milano-Bicocca, 2018. http://hdl.handle.net/10281/198942.
Texte intégralRésumé :
Il rivestimento dei batteri Gram negativi consiste in una membrana interna (IM) e una membrana esterna (OM) separate da uno spazio periplasmatico contenente un sottile strato di peptidoglicano (PG) ancorato alla OM tramite la lipoproteina di Braun (LPP). Mentre la IM è costituita da un doppio strato di fosfolipidi, la OM è una membrana lipidica asimmetrica, contenente fosfolipidi nel foglietto interno, e un lipide complesso il Lipopolisaccaride (LPS) nel foglietto esterno.
Il LPS sintetizzato nel citoplasma, viene traslocato sul lato periplasmatico della IM e preso in carico dal complesso multiproteico Lpt (LPS transport), composto in Escherichia coli da sette proteine essenziali (Lpt ABCDEFG) che si occupano del suo trasporto fino al raggiungimento della sua sede finale, la OM.
Analisi biochimiche hanno dimostrato che le sette proteine Lpt formano un complesso “transenvelope” che connette IM e OM e studi di tipo genetico suggeriscono che esse operino in concerto come un singolo macchinario. Infatti, la deplezione di un qualsiasi componente del complesso Lpt causa lo stesso fenotipo, ovvero l’accumulo del LPS nel versante periplasmatico della IM, la decorazione del LPS con acido colanico e la formazione di una IM anomala, con una densità intermedia tra la IM e la OM.
Nel nostro laboratorio è stata condotta l’analisi differenziale del proteoma delle membrane totali di E. coli in deplezione di LptC, per studiare la risposta globale al blocco del trasporto del LPS. Tra le proteine il cui livello cambia nel confronto tra il ceppo non depleto e il depleto sono state trovate proteine coinvolte nella biogenesi e nel rimodellamento del PG.
Lo scopo di questa tesi è stato lo studio della correlazione tra il blocco del LPS e il rimodellamento del PG.
Inizialmente è stata analizzata la struttura del PG in deplezione di LptC. Questa analisi ha evidenziato che in questa condizione la struttura del PG varia sia per composizione che per tipo di legami crociati tra i filamenti glicanici adiacenti.
Nei batteri Gram negativi il legame tra i filamenti glicanici è generalmente un legame diretto 3-4, che si forma tra il gruppo aminico del diaminoacido in posizione 3 di un tetrapeptide e il gruppo carbossilico della D-alanina in posizione 4 del tretrapeptide adiacente. Il legame 3-4 avviene ad opera delle D,D transpeptidasi PBP. Un altro tipo di legame crociato presente nel PG è quello tipo 3-3 che si forma tra il gruppo aminico del diaminoacido in posizione 3 ed il gruppo carbossilico del diaminoacido presente nel tetrapeptide del filamento glicanico adiacente ed è catalizzato da L,D-transpeptidasi .
In E. coli, sono noti cinque enzimi con attività L,D-transpeptidasica, di cui tre (LdtA, LdtB, LdtC) ancorano la lipoproteina più abbondante della OM (lipoproteina di Braun) al PG e due (LdtD, LdtE) catalizzano il legame crociato 3-3. La delezione di tutti questi geni, singolarmente o in combinazione, non presenta nessun fenotipo, suggerendo che in condizioni normali questo legame è dispensabile.
Per studiare la correlazione tra il legame crociato 3-3 e il blocco del trasporto del LPS abbiamo creato mutanti arabinosio dipendenti per alcuni dei componenti del sistema Lpt deleti contemporaneamente per i geni che esprimono le L,D-transpeptidasi LdtD e LdtE.
In precedenza, nel nostro laboratorio è stato dimostrato che la deplezione di uno qualsiasi dei geni lpt causa la formazione di cellule filamentose e l’arresto della crescita ma non la lisi cellulare. Invece, nei mutanti ΔldtDΔldtE, in deplezione dei geni lpt, oltre alla formazione di cellule filamentose si osserva la formazione di un setto anomalo e la lisi cellulare. Questi dati suggeriscono che il rimodellamento del peptidoglicano a seguito della formazione di legami 3-3 potrebbe essere una forma di riposta al danno alla membrana esterna.The cell envelope of Gram-negative bacteria is a complex multi-layered structure consisting of a cytoplasmic and an outer membrane (CM and OM), which delimit the periplasm containing a thin layer of peptidoglycan (PG) called the sacculus. The primary function of the OM is to establish a selective permeability barrier that enables the cell to maintain favourable intracellular conditions even in hash environments and the lipopolysaccharide (LPS) layer greatly contributes to this peculiar property. The integrity of the PG mesh is essential to protect the cell from bursting due to its turgor and maintain the shape of the cell. OM and PG are synthetized and assembled by multiprotein machineries that need to be finely coordinated as imbalanced growth of these layers may compromise structural integrity of the cell. In order to gain more insight in the mechanism by which the cells coordinate the growth of these two layers, we analysed the PG composition when the biogenesis of OM is compromised due to the block of LPS transport. In this work we shown that when OM is impaired, E. coli cells remodel PG architecture by increasing the non-canonical 3- 3 cross-linkage. We can assume that this is a salvage mechanism to prevent cell lysis when OM is damaged.
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Mizutani, Teruyoshi, Kenta Shinmura, Kazue Kaneko, Tatsuo Mori, Mitsugu Ishioka et Tatsuya Nagata. « Space Charge Behavior near LDPE / LDPE Interface ». IEEE, 2000. http://hdl.handle.net/2237/7162.
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Cömert, Engin. « Utvärdering av karboniserad LDPE som egenskapsförbättrande tillsats i nya LDPE-filmer ». Thesis, KTH, Skolan för kemi, bioteknologi och hälsa (CBH), 2018. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-240303.
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Tidigare forskning har visat att med hjälp av en speciell mikrovågsugn så kan man omvandla lågdensitetspolyeten (LDPE) till kemikalier med högre värde [1]. Ett försök på att omvandla plastavfall (LDPE) till en produkt med högre värde kommer att göras i detta projekt. Att kunna återvinna plast är en fråga som under de senaste åren har växt och fortsätter växa, i dagsläget så finns det ett intresse att kunna producera nya produkter från återvunnet material [2]. Eftersom plaster succesivt förlorar sina egenskaper varje gång de värms upp så är det ofta enklare för ett företag att skapa och använda ny plast. Plast som kan ha förlorat sina mekaniska egenskaper eller eventuellt har förorenats är inte något som efterfrågas [3] [4]. Kolprickar är ett slags nanomaterial som har fascinerande egenskaper och som börjats forska mer och mer om under de senaste 10 åren. Under detta projekt kommer det stora fokus ligga på om man kan tillverka denna typ av partiklar genom karbonisering av LDPE och hur tillsats av denna typ av partiklar påverkar de mekaniska egenskaperna hos nya LDPE produkter [5]. Under detta projekt användes en speciell mikrovågsugn för karbonisering av polyeten, genom användning av mikrovågsugnen med salpetersyra och saltsyra som katalysatorer så kunde man syntetisera fram dispergerade partiklar (DP) och fasta partiklar (FP) från LDPE. Dispergerade partiklarnas och fasta partiklarnas strukturella egenskaper analyserades genom användning av FT-IR och XRD. Analys av partikelstorlek för dispergerade partiklarna gjordes genom DLS och morfologi undersöktes med SEM. I detta projekt visades det att man hade lyckats ändra polyetenets strukturella egenskaper då nya grupper kunde ses på FT-IR och XRD. Partikelstorleken mättes också och man kom fram till att det var grova partiklar som bildades och att de inte var så homogena. Tillverkning av kompositfilmer innehållande dispergerade partiklar och fasta partiklar lyckades man också åstadkomma. Kompositerna bestod av 0,5 vikt-% DP som blandades med 99,5 vikt-% LDPE pulver. En annan komposit gjordes också fast här ökade man viktsprocenten av partiklar till 2,5 vikt-% DP som blandades med 97,5 vikt-% LDPE pulver. Kompositerna innehållande FP skapades genom att blanda 5 vikt-% och 10 vikt-% FP med 95 vikt-% och 90 vikt-% LDPE pulver. Filmernas mekaniska egenskaper analyserades genom dragprovning, resultaten visade sig att dragspänningen för kompositfilmerna innehållande DP gav ett styvare material än filmen med endast LDPE. Kompositfilmerna med FP fick däremot ett mycket högre modulus än dem andra, materialet hade alltså blivit mycket styvare och en stor del av flexibiliteten hade gått förlorad. Slutsatsen man kunde komma fram till var att metoden kan användas för att skapa ett material som är starkare och mer styvt.Previous research has shown that with the assistance of a specially formed microwave oven you can degrade low density polyethylene (LDPE) to chemicals with more value, so this project will try to reform plastic waste (LDPE) to a product with more value. Being able to recycle plastic is a question that has grown these past years and is still growing. As things stand there is an interest in being able to produce plastics that can be recycled. Because plastics lose some of their mechanical properties every time they are heated the companies who produce them find it easier and cheaper to just use new plastic. Therefore, to be able to produce a plastic which does not lose its mechanical properties is something that is being strived for. Carbon dots is a new kind of nanomaterial that has fascinating properties and research on it and its properties has been done during the last 10 years. During this project the main focus will therefore be to evaluate whether LDPE can be carbonized to carbon dot like materials and whether addition of these affects the mechanical properties of new LDPE products. By using the special microwave, the synthesis of carbon dots was successful. In addition, solid particles we gained from LDPE. The structural properties of the carbon dots and solid particles were analysed by using FT-IR, NMR and XRD. There was also an analysis on the particle sizes which was done by using DLS and morphological evaluation which was performed by SEM. The synthesized particles were also put into TGA to evaluate their thermal stability. The synthesis was successful, and you could see a change in the particles structure because new functional groups could be found by using FT-IR, NMR and XRD. The particle size was also measured, and the consensus was that the particles were coarse and not that homogenous. Making of the composites with the carbon dots and solid particles is also something that was successfully done. The composites contained 0.5 wt-% of synthesized carbon dots and 99.5 wt-% of LDPE powder and another one where 2.5 wt-% of synthesized carbon dots was mixed with 97.5 wt-% of LDPE powder. The solid particle composites were created by mixing 5 wt-% and 10 wt-% solid particles mixed with 95 wt-% and 90 wt-% of LDPE powder. The mechanical properties were analysed with a tensile testing machine, the result that was retrieved from the machine was that the films made of the composites with DP gave a stiffer material than the film made only by LDPE. The composite films with FP gave a much higher modulus than the other films made by addition of DP. The results show that the films with FP were also a lot stiffer than the film with only LDPE. The conclusion is that you can use this method to create a material that is stronger and stiffer.
4
Steffl, Thomas. « Rheological and film blowing properties of various low density polyethylenes and their blends ». [S.l.] : [s.n.], 2004. http://deposit.ddb.de/cgi-bin/dokserv?idn=972028625.
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Olyveira, Gabriel Molina de. « Preparação e caracterização de nanocompósitos de LDPE e LDPE/EVA com partículas de Ag/TIO2 para aplicações antimicrobiais ». Universidade Federal de São Carlos, 2009. https://repositorio.ufscar.br/handle/ufscar/854.
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Previous issue date: 2009-10-02Universidade Federal de Sao Carlos
This study investigated the use of a charger inorganic (titanium dioxide) as a support for silver nanoparticles and evaluated the use of material obtained as filler in polymer for antimicrobial application.Silver nanoparticles-titanium dioxide were synthesized by the reduction method developed by Turkevich, also known as a method of citrate. Therefore, we used three different types of titanium dioxide in the colloidal synthesis and found that nanometer titanium dioxide showed better results for the deposition of silver nanoparticles. Silver Nitrate was reduced by sodium citrate with and without the presence of a surfactant (PVP-Polyvinylpyrrolidone) resulting in a stable suspension of nanoparticles of silver / titanium dioxide. We also tested NH4OH (ammonium hydroxide) to prevent the growth of nanoparticles during the reaction. Nanocomposite of LDPE and LDPE / EVA were produced by mixing in the molten state with the Ag nanoparticles-titanium dioxide resulting from the colloidal synthesis. By assessing the rheological, thermal and morphological analysis we found that compared with nanocomposite LDPE / EVA, LDPE nanocomposite showed better results with regard to dispersion of the charges, but nanocomposite LDPE / EVA showed better results in antimicrobial assays due to the polar nature the grouping of EVA able to bind more easily to inorganic fillers.
Neste trabalho foi estudada a utilização de um carregador inorgânico (dióxido de titânio) como suporte para as nanopartículas de prata e avaliado o uso do material obtido como carga em polímeros para aplicação antimicrobial. Nanopartículas de prata-dióxido de titânio foram sintetizadas pelo método de redução desenvolvido por Turkevich, também conhecido como método do citrato. Para tanto foram utilizados 3 diferentes tipos de dióxido de titânio na síntese coloidal e verificou-se que os dióxidos de titânio na forma nanométrica apresentaram melhores resultados quanto a deposição das nanopartículas de prata. O Sal de Prata (Nitrato de Prata) foi reduzido pelo citrato de sódio sem e com a presença de um surfactante (PVP- Polivinilpirrolidona) resultando numa suspensão estabilizada de nanopartículas de prata / dióxido de titânio. Foi testado também a presença de um agente moderador da reação, NH4OH (hidróxido de amônia), para evitar o crescimento das nanopartículas durante a reação. Os nanocompósitos de LDPE e LDPE/EVA foram produzidos através da mistura no estado fundido com as nanopartículas de Ag- dióxido de titânio resultantes da síntese coloidal. Através das análises reológicas, térmicas e morfológicas constatou-se que em comparação com o nanocompósito LDPE/EVA, o nanocompósito com LDPE apresentou resultados melhores quanto a dispersão das cargas, porém o nanocompósito LDPE/EVA apresentou melhores resultados nos ensaios antimicrobiais devido a natureza polar do grupamento do EVA capaz de se ligar mais facilmente às cargas inorgânicas.
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Riess, Katrin. « Plasmamodifizierung von Polyethylen ». [S.l. : s.n.], 2001. http://deposit.ddb.de/cgi-bin/dokserv?idn=961745886.
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Andersen, Bistra. « Investigations on environmental stress cracking resistance of LDPE/EVA blends ». [S.l. : s.n.], 2004. http://deposit.ddb.de/cgi-bin/dokserv?idn=972520481.
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Hendry, Benjamin H. « Evaluation of post-residential LDPE recycling in Georgia ». Thesis, Georgia Institute of Technology, 1991. http://hdl.handle.net/1853/28817.
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Chalapati, Sachin. « Toluene Mediated FCC of LDPE Using Ionic liquids ». Thesis, Högskolan i Borås, Institutionen Ingenjörshögskolan, 2014. http://urn.kb.se/resolve?urn=urn:nbn:se:hb:diva-17973.
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Polyethylene is one of the most widely used synthetic materials produced by mankind and its accumulation in the biosphere is exceeding at an alarming rate. There are several methods to recycle or remediate the waste polyethene apart from land filling and generation of useful products from the waste is on demand for research and development. Ionic liquids are aggressively replacing several organic compounds due to their robust nature and also have novel properties that allow depolymerization of synthetic materials into simpler short chained paraffins. Initial dissolution of polymer using hot toluene followed by agitated depolymerization using EMIM-Cl (AlCl3) ionic liquid for producing fuel grade high calorie organic molecules might be proven successful. This method uses proton sources like sulphuric acid, hydrochloric acid or waters that aid saturation of organic compounds by hydrogen ion exchange. This could be a novel procedure that aims to produce fuel grade products from waste synthetic polymers like polyethene.Program: Master of Science with a Major in Resource recovery – Industrial biotechnology
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Rabie, Allan John. « Blends with low-density polyethylene (LDPE) and plastomers ». Thesis, Stellenbosch : Stellenbosch University, 2004. http://hdl.handle.net/10019.1/49870.
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Thesis (MSc)--Stellenbosch University, 2004.ENGLISH ABSTRACT: This study describes the design, building and optimization of a fully functional preparative TREF (Prep-TREF) apparatus. This apparatus allows for the fractionation of semicrystalline polyolefins according to the crystallizability of the molecules. Various factors, such as the sample cooling rate and the effect of on-support and off-support crystallization, are investigated. The preparative TREF is used to fractionate a commercial low-density polyethylene (LOPE), two commercially available plastomers (polyethylene-l-octene copolymers), as well as blends of the LOPE and the respective plastomers. It is shown that in each case the samples fractionated by crystallizability. The fractions recovered from the Prep-TREF were characterized by CRYSTAF, OSC and NMR analysis. It is shown how the results of this preparative fractionation allow for a better understanding of the molecular heterogeneity in the LOPE and plastomers. New ways of presenting the data from the preparative fractionation, in terms of 3- dimensional plots, are also investigated. These plots offer a novel way of presenting the molecular heterogeneity in the samples in terms of the molecular crystallizability. These plots highlight features that are difficult to detect in the conventional two-dimensional plots. In conclusion, the influences of various blending ratios of LOPE and plastomer on the morphological and physical properties of the blends, such as haze, clarity, and tear-and impact strength are determined.
AFRIKAANSE OPSOMMING: Die doel van hierdie studie was die ontwikkeling en optimisering van 'n ten volle funksionerende TREF. Hierdie tegniek word gebruik om polimeermengsels te fraksioneer deur gebruik te maak van die kristaliseerbaarheid van polimere. Verskeie faktore soos die afkoel spoed en die effect van met en sonder 'n ondersteuning(seesand) vir kristaliseering was ondersoek. Hierna is navorsing gedoen om 'n beter begrip ten opsigte van die meganiese, fisiese en optiese eienskappe van lae-digtheid poliëtileen (LDPE) te ontwikkel. Hierdie LDPE is met die affiniteitsreeks plastomere van die maatskappy, Dow Chemicals, gemeng om tendense in die gefraksioneerde polimere te indentifiseer. Een van Sasol se kommersiële LDPE produkte en twee van Dow Chemicals se plastomere is individueel gefraksioneer. Die mengsel van die twee ongefraksioneerde LDPE en plastomere is nog nooit voorheen op 'n molekulêre basis ondersoek nie. Dit is in hierdie studie gedoen deur van TREF gebruik te maak. Nuwe maniere is ontwikkel om data op 'n nuwe manier voor te stel deur middel van 3 Dimensionele grafieke te skep om resultate voor te stel wat andersins baie moelilik was om voor te stel in een dimensie agv die hoeveelheid data wat geinterpreteer word. Ten slotte is die invloed van die verskillende mengverhoudings van LDPE en plastomere op die morfologiese en fisiese eienskappe soos deursigtigheid, helderheid, skeur- en impaksterkte, ook ondersoek.
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Zhang, Chao, Teruyoshi Mizutani, Kazue Kaneko, Tatsuo Mori et Mitsugu Ishioka. « Space charge and conduction in LDPE-polypropylene copolymer blends ». IEEE, 2001. http://hdl.handle.net/2237/7163.
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Lee, David Shu Chung 1970. « Rheological characterization of LDPE and PMMA with optical methods ». Thesis, Massachusetts Institute of Technology, 1988. http://hdl.handle.net/1721.1/9963.
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Fries, Sebastian [Verfasser]. « Modelling of Fouling Mechanisms in the LDPE Synthesis / Sebastian Fries ». Düren : Shaker, 2020. http://d-nb.info/1208599321/34.
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Blok, Achim Arno. « Analytische Modellierung des Spannungszustandes mehrteiliger Querpressverbände im Zylinder von LDPE-Höchstdruckverdichtern / ». Aachen : Shaker, 2006. http://bvbr.bib-bvb.de:8991/F?func=service&doc_library=BVB01&doc_number=014900331&line_number=0001&func_code=DB_RECORDS&service_type=MEDIA.
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Santos, Rita de Cássia dos. « Caracterização vibracional e térmica de blendas de LDPE e m-LLDPE ». Universidade de São Paulo, 2005. http://www.teses.usp.br/teses/disponiveis/46/46132/tde-06032007-220909/.
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As blendas de polietileno de baixa densidade (LDPE) com o polietileno linear de baixa densidade (LLDPE) são utilizadas comercialmente com o objetivo de melhorar as propriedades finais dos produtos e o seu processamento, minimizar custos de produção tendo, como seu principal segmento, filmes para embalagens. O LLDPE utilizado neste trabalho foi sintetizado a partir do catalisador de metaloceno (m-LLDPE) que foi projetado para oferecer melhores propriedades mecânicas em relação ao LLDPE sintetizado por catalisador Ziegler-Natta. O m-LLDPE quando comparado ao LLDPE (Ziegler-Natta) apresenta resistência ao impacto do dardo quatro vezes maior e resistência ao rasgo de duas a quatro vezes maior, menor temperatura de selagem e melhor processabilidade. O LDPE tem boa processabilidade, oferece grande estabilidade ao balão durante o processo de extrusão por sopro e apresenta boas propriedades ópticas. Este trabalho reúne a caracterização térmica, vibracional e ensaios físico-químicos e mecânicos, do LDPE, m-LLDPE e as blendas de LDPE/m-LLDPE na proporção em massa de 75/25, 50/50 e 25/75. Na caracterização térmica foram utilizadas as técnicas: termogravimetria (TG), calorimetria exploratória diferencial (DSC) e análise térmica dinâmico-mecânica (DTMA). Na caracterização vibracional utilizou-se a espectroscopia fotoacústica no infravermelho (PAS-IR) e espectroscopia Raman. Foi utilizada a técnica de difração de raios-X (WAXD) para complementação dos resultados. Nos ensaios físico-químicos e mecânicos foram avaliadas as propriedades ópticas, rasgo de Elmendorf, propriedades de tração, resistência ao impacto do dardo e resistência da termossoldagem à tração. Por estas técnicas foram avaliadas as características térmicas e estruturais dos polímeros e seu comportamento nas blendas. Pela técnica de DSC foi possível verificar a imiscibilidade destas blendas. As técnicas PAS-IR, Raman e WAXD apresentam perfis espectrais semelhantes não possibilitando distinção entre as blendas de composição diferentes. Os resultados de DSC, PAS-IR e WAXD mostraram que não ocorrem mudanças significativas no grau de cristalinidade das blendas. Os ensaios de brilho 45° e opacidade mostram as boas propriedades ópticas do LDPE e suas blendas. Os ensaios mecânicos mostram que o m-LLDPE e suas blendas apresenta boas propriedades mecânicas e boa soldabilidade. Foi possível determinar a blenda que é melhor indicada para os vários segmentos do mercado de embalagens. As blendas de LDPE/m-LLDPE mais utilizadas pela indústria são as de 25/75 ou 75/25, para diferentes tipos de aplicação.Blends of low density polyethylene (LDPE) and linear low density polyethylene (LLDPE) are used commercially to improve the final properties of the products and their process, reduce the production cost having as their main segment packing film. The LLDPE used in this work was synthesized with the metallocene catalyst (m-LLDPE), which was projected to offer better mechanical properties in relation to the LLDPE synthesized by Ziegler-Natta catalyst. The m-LLDPE, when compared to the LLDPE (Ziegler-Natta) present dart impact strength four times stronger and the tearing resistance two to four times bigger, lower sealing temperature and good processability. The LDPE has good processability, offers great estability to the baloon during the process of blown extrusion and shows good optical properties. This work brings together the thermal and vibrational characterization, physical chemistry and mechanical tests, of the LDPE, m-LLDPE and the blends of LDPE/m-LLDPE in a 75/25, 50/50 and 25/75 parts by weight. In the thermal characterization several techniques were used: termogravimetry (TG), differential scanning calorimetry (DSC) and dynamic mechanical analyser (DTMA). In the vibrational characterization, the photoacoustic spectroscopy (PAS-IR) and Raman spectroscopy were used. The X-ray diffraction (WAXD) was used to complete the results. The physical chemistry and mechanical tests evaluated optical properties, Elmendorf tearing, tensile strength, dart impact strength, heat sealing strength and hot tack strength. With these techniques the thermal characterization and the polymer structure were evaluated as well as the blend behaviour. Using the DSC technique it was possible to observe that the blends are immiscible. The PAS-IR, Raman and WAXD techniques present spectral profiles not allowing a distinction between the blends with different composition. The results of DSC, PAS-IR and WAXD show that significant changes of crystallization of the blends haven\' t occurred. The gloss 45° and haze show the good optical properties of the LDPE and their blends. The mechanical tests demonstrate the good mechanical properties and soldability of the m-LLDPE and their blends. It was possible to determine the blend that best fit the different segments of the packing market. The most frequently LDPE/m-LLDPE blends used by industry are the 25/75 or 75/25, for different applications.
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INACIO, WILLIAM BUSCHLE ROMARIZ. « EFFECT OF REPROCESSING ON THE MECHANICAL PROPERTIES OF A HDPE/LDPE BLEND ». PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIRO, 2018. http://www.maxwell.vrac.puc-rio.br/Busca_etds.php?strSecao=resultado&nrSeq=34970@1.
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PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIROOs termoplásticos representam a grande maioria dos polímeros empregados hoje em dia e a grande vantagem de sua aplicação é que podem ser reaquecidos e moldados repetidamente. Com a crise do petróleo em 1973, os custos para transformar o petróleo em materiais plásticos se tornaram mais atrativos do que transformá-lo em materiais mais tradicionais. Com isso, os investimentos nas indústrias de transformação cresceram, ao mesmo tempo que a preocupação com o meio ambiente. Devido a facilidade de reprocessar esses materiais a temperaturas moderadas, muitas empresas passaram a reutilizar seus resíduos dentro de seus próprios processos. Neste escopo, esse trabalho tem como objetivo estudar o comportamento mecânico do polietileno de baixa densidade (PEBD) e de uma mistura física formada por polietileno de baixa densidade (PEAD) e polietileno de alta densidade, com uma proporção de 80/20, ao serem submetidos a diversos ciclos de processamento. Os materiais estudados foram preparados e doados pela Companhia de Canetas Compactor. Para este estudo, o material sofreu dez etapas de injeção/extrusão. A partir de ensaios de tração foram determinadas as tensões e cargas máximas suportadas, calculando-se em seguida o módulo de elasticidade, alongamento e tenacidade de cada material. A adição do PEAD é responsável por aumentar a resistência e a dureza do material. Do ponto de vista prático, o material reprocessado não apresentou mudanças significativas de performance. Análises por infravermelho mostraram que não há degradação por oxidação ao longo do processo de reciclagem.
Thermoplastics are the most used polymers nowadays on account of being easily reprocessable with high temperatures. During the oil crisis in 1973 the costs of transforming oil into plastic materials became more attractive than turning them into more traditional materials. Furthermore, the investments in transformation industries grew alongside the concern for the environment. Due to the ease of reprocessing these materials a lot of companies started recycling them within their process. In this context, the present study aims to analyze the mechanical behavior of a low density polyethylene (LDPE) and high density polyethylene (HDPE) blend and pure LDPE after 10 cycles of reprocessing. The polymers were donated by Companhia de Canetas Compactor. The materials suffered up to 10 cycles of injection moulding/extrusion. Tensile tests were made to determine the maximum yield stress and maximum load allowed. Afterwards, calculations were made to determine elongation, Young modulus and toughness. The HDPE addition was responsible to raise the materials yield stress and hardness. From a practical point of view the reprocessing didn t affect significantly the materials performance. FTIR analyses didn t detect oxidation through the process.
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Ferri, Dino <1968>. « Correlazioni tra proprietá reologiche, struttura e processabilitá di blend di LLDPE/LDPE ». Doctoral thesis, Alma Mater Studiorum - Università di Bologna, 2010. http://amsdottorato.unibo.it/2396/1/Ferri_Dino_tesi.pdf.
Texte intégralRésumé :
Polymer blends constitute a valuable way to produce relatively low cost new materials. A still open question concerns the miscibility of polyethylene blends. Deviations from the log-additivity rule of the newtonian viscosity are often taken as a signature of immiscibility of the two components. The aim of this thesis is to characterize the rheological behavior in shear and elongation of five series of LLDPE/LDPE blends whose parent polymers have been chosen with different viscosity and SCB content and length. Synergistic effects have been measured for both zero shear viscosity and melt strength. Both SCB length and viscosity ratio between the components have been found to be key parameters for the miscibility of the pure polymers. In particular the miscibility increases with increasing SCB length and with decreasing the LDPE molecular weight and viscosity.
This rheological behavior has significant effects on the processability window of these blends when the uni or biaxial elongational flows are involved. The film blowing is one of the processes for which the synergistic effects above mentioned can be crucial. Small scale experiments of film blowing performed for one of the series of blends has demonstrated that the positive deviation of the melt strength enlarges the processability window. In particular, the bubble stability was found to improve or disappear when the melt strength of the samples increased.
The blending of LDPE and LLDPE can even reduce undesired melt flow instability phenomena widening, as a consequence, the processability window in extrusion. One of the series of blends has been characterized by means of capillary rheometry in order to allow a careful morphological analysis of the surface of the extruded polymer jets by means of Scanning Electron Microscopy (SEM) with the aim to detect the very early stages of the small scale melt instabilty at low shear rates (sharksin) and to follow its subsequent evolution as long as the shear rate was increased. With this experimental procedure it was possible to evaluate the shear rate ranges corresponding to different flow regions: smooth extrudate surface (absence of instability), sharkskin (small scale instability produced at the capillary exit), stick-slip transition (instability involving the whole capillary wall) and gross melt fracture (i.e. a large scale "upstream" instability originating from the entrance region of the capillary). A quantitative map was finally worked out using which an assessment of the flow type for a given shear rate and blend composition can be predicted.
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Ferri, Dino <1968>. « Correlazioni tra proprietá reologiche, struttura e processabilitá di blend di LLDPE/LDPE ». Doctoral thesis, Alma Mater Studiorum - Università di Bologna, 2010. http://amsdottorato.unibo.it/2396/.
Texte intégralRésumé :
Polymer blends constitute a valuable way to produce relatively low cost new materials. A still open question concerns the miscibility of polyethylene blends. Deviations from the log-additivity rule of the newtonian viscosity are often taken as a signature of immiscibility of the two components. The aim of this thesis is to characterize the rheological behavior in shear and elongation of five series of LLDPE/LDPE blends whose parent polymers have been chosen with different viscosity and SCB content and length. Synergistic effects have been measured for both zero shear viscosity and melt strength. Both SCB length and viscosity ratio between the components have been found to be key parameters for the miscibility of the pure polymers. In particular the miscibility increases with increasing SCB length and with decreasing the LDPE molecular weight and viscosity.
This rheological behavior has significant effects on the processability window of these blends when the uni or biaxial elongational flows are involved. The film blowing is one of the processes for which the synergistic effects above mentioned can be crucial. Small scale experiments of film blowing performed for one of the series of blends has demonstrated that the positive deviation of the melt strength enlarges the processability window. In particular, the bubble stability was found to improve or disappear when the melt strength of the samples increased.
The blending of LDPE and LLDPE can even reduce undesired melt flow instability phenomena widening, as a consequence, the processability window in extrusion. One of the series of blends has been characterized by means of capillary rheometry in order to allow a careful morphological analysis of the surface of the extruded polymer jets by means of Scanning Electron Microscopy (SEM) with the aim to detect the very early stages of the small scale melt instabilty at low shear rates (sharksin) and to follow its subsequent evolution as long as the shear rate was increased. With this experimental procedure it was possible to evaluate the shear rate ranges corresponding to different flow regions: smooth extrudate surface (absence of instability), sharkskin (small scale instability produced at the capillary exit), stick-slip transition (instability involving the whole capillary wall) and gross melt fracture (i.e. a large scale "upstream" instability originating from the entrance region of the capillary). A quantitative map was finally worked out using which an assessment of the flow type for a given shear rate and blend composition can be predicted.
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Mizutani, Teruyoshi, Kenta Shimnmura, Kazue Kaneko, Tatsuo Mori, Mitsugu Ishioka et Tatsuya Nagata. « Space Charge Behaviors near the Interface between Different Low-Density Polyethylenes ». IEEE, 2000. http://hdl.handle.net/2237/7176.
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Kaneko, K., H. Semi, T. Mizutani, T. Mori et M. Ishioka. « Charge Transport and Space Charge Formation in Low-Density Polyethylene ». IEEE, 2000. http://hdl.handle.net/2237/7177.
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Pflug, Kristina Maria [Verfasser]. « Linking Reaction Conditions with Polymer Properties for the LDPE Process / Kristina Maria Pflug ». Aachen : Shaker, 2018. http://d-nb.info/1188550616/34.
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Broussot, Loïc. « Implication du noyau latérodorsal du tegmentum dans les réponses au stress adaptatives et mésadaptées ». Electronic Thesis or Diss., Université Côte d'Azur, 2020. http://theses.univ-cotedazur.fr/2020COAZ6014.
Texte intégralRésumé :
La réponse comportementale au stress est un mécanisme adaptatif qui permet à l’organisme de gérer les stimuli environnementaux nocifs. Les circuits qui la sous-tendent peuvent cependant être dérégulés par un stress intense ou chronique, conduisant à des troubles neuropsychiatriques. L’aire tegmentale ventrale (ATV) est une région du mésencéphale qui joue un rôle crucial dans le traitement de la récompense et l’aversion. On sait qu’elle influence la réponse au stress, mais notre connaissance sur ce rôle reste limitée car on ignore la plupart des structures régulatrices qui le sous-tendent. Le noyau latérodorsal du tegmental (LDTg) est une structure du tronc cérébral qui régule l’activité de l’ATV. Si son influence sur la récompense a été largement décrite, son rôle dans la réponse au stress reste encore inconnu.Cette thèse explore le rôle du LDTg dans deux types de réponse au stress : 1) Les comportements défensifs adaptés face à un stress aigu. 2) Les troubles comportementaux mésadaptés résultant d’un stress chronique. Pour comprendre le rôle du LDTg dans chacune, nous avons utilisé des outils pharmacogénétiques et optogénétiques pour moduler son activité durant des situations stressantes et en observer les effets comportementaux. En administrant de courts chocs électriques, nous avons évalué le rôle du LDTg dans un comportement défensif adaptatif d’immobilisation appelé freezing. Nous avons inhibé sélectivement les projections du LDTg de différentes natures et ciblant différentes structures afin de montrer que les projections GABAergiques du LDTg vers l’ATV régulent le freezing de manière bidirectionnelle. De la même façon, l’utilisation d’outils pharmacogénétiques dans un modèle de souris soumis à un stress social chronique nous a permis d’évaluer le rôle du LDTg dans des comportements de type dépressif. Les projections cholinergiques, mais pas glutamatergiques, du LDTg vers l’ATV sont ainsi nécessaires à l’induction des troubles de type dépressif par un stress chronique.En conclusion, ces résultats nous ont permis de mettre en évidence un rôle nouveau de l’axe LDTg-ATV dans la réponse au stress. Il est impliqué à la fois dans les réponses défensives adaptatives et les troubles comportementaux liés au stress. Ces informations pourraient aider dans le futur au développement de nouvelles thérapies innovantes basées sur la modulation des circuits cérébrauxThe behavioural stress response is an adaptive mechanism that allows an organism to cope with threatening environmental stimuli. However, the circuitries that underlie it can be deregulated by intense or chronic stress and lead to maladaptive neuropsychiatric disorders. The ventral tegmental area (VTA) is a midbrain region that plays a crucial role in reward and aversion processing. It also influences the stress response, but our understanding of its role is still limited as the regulatory inputs that shape its activity during stress remain largely unknown. The laterodorsal tegmental nucleus (LDTg) is a brainstem structure regulating VTA activity. While its influence on reward processing has been widely described, its role in the stress response has yet to be determined.This thesis explores the role of the LDTg in two types of stress responses: 1) Adaptive defensive behaviours under acute stress. 2) Maladaptive behaviours following chronic stress. To assess the role of the LDTg in both contexts, we used chemogenetic and optogenetic tools to modulate its activity in mice during stressful situations and observed how it altered their behavioural responses.By using acute electrical shocks, we measured the influence of the LDTg over the freezing defensive response, an adaptive behaviour in mice confronted to an unseen threat. By selectively inhibiting LDTg projections of various natures and to different targets, we unravelled a new GABAergic LDTg-VTA pathway that bidirectionally modulates freezing in response to acute stress. Similarly, we used selective chemogenetic silencing in a mouse model of chronic social defeat to assess the role of the LDTg in stress-related depressive-like disorders. Cholinergic, but not glutamatergic, LDTg projections to the VTA were sufficient and necessary to induce depressive-like disorders after chronic stress. Together, these results unravel a new role of the LDTg-VTA axis in the regulation of the stress response. We show it is involved in both adaptive defensive behaviours and maladaptive stress-related disorders through converging yet different pathways. This may open a new therapeutic window for innovative treatments based on cerebral modulation
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Blok, Achim A. [Verfasser]. « Analytische Modellierung des Spannungszustandes mehrteiliger Querpressverbände im Zylinder von LDPE-Höchstdruckverdichtern / Achim A Blok ». Aachen : Shaker, 2006. http://d-nb.info/1170529291/34.
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Eckes, David [Verfasser]. « Modelling of the Industrial LDPE-Synthesis for the Tail-End Reactor Technology / David Eckes ». Aachen : Shaker, 2018. http://d-nb.info/1162794291/34.
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Ruiz, Ilza Aparecida dos Santos. « Adição de EPDM ou anidrido maléico na blenda LDPE/PA6 e suas propriedades finais ». Universidade de São Paulo, 2008. http://www.teses.usp.br/teses/disponiveis/3/3133/tde-11052009-133033/.
Texte intégralRésumé :
Em virtude do crescente volume da utilização de embalagens multicamadas na preservação de alimentos, torna-se necessário o estudo visando a reciclagem desses materiais através de seu reaproveitamento como matéria-prima e a transformação em novos produtos ou materiais. Dentre os vários tipos de reciclagem utilizados atualmente, a formação de blendas poliméricas com material descartado apresenta-se como uma alternativa viável, pois se trata de uma atividade moderna que une o desenvolvimento tecnológico e a preservação ambiental. O presente trabalho faz um estudo sobre a reciclagem de resíduos de embalagens multicamadas pós-consumo no setor alimentício para a formação de uma blenda. O filme multicamada composto por poliamida 6 e polietileno de baixa densidade foi previamente moído para obtenção de flocos e a ele foi adicionado primeiramente o aditivo etileno-propileno-dieno monômero e em seguida foi feito uma nova mistura composta apenas de anidrido maléico com filme multicamada na forma de flocos, no intuito de melhorar as propriedades mecânicas das blendas formadas pelo processo da extrusão. Para a verificação dos resultados obtidos foram realizados testes de tração, alongamento e permeabilidade ao gás oxigênio no filme de poliamida 6 e polietileno, e ensaios mecânicos, análises térmicas e microscopia eletrônica de varredura nas blendas obtidas. Também se estudou o efeito da radiação (100 kGy) sobre as propriedades das blendas utilizando-se um acelerador de elétrons.In virtue of the increasing volume of the multilayers packings use in the food preservation, the study for the recycling of these materials through its reverse speed-exploitation as raw material and the transformation in new products or materials becomes necessary. Amongst some types of recycling used currently, the polymers blendes formation with discarded material is presented as a viable alternative, therefore if it deals with a modern activity that joins the technological development and the ambient preservation. The present research, therefore makes a study on the recycling of residues from multilayers packings after-consumes in the nourishing sector for the blend formation. The multilayer film composed by polyamide 6 and polyethylene of low density was previously worn out for flake attainment and it was added first the Ethylene-Propylene-Diene-Monomer (EPDM) additive and after that a new composed maleic anhydride mixture was made only with multilayer film in the flake form, in intention to improve the mechanical properties of blendes formed for the process of the drawing. For verification of the results assays had been carried through traction tests, rupture lengthening tests and permeability to the gas oxygen in the film of polyamide 6 and mechanical properties of blendes formed for the process of the drawing. For verification of the results assays had been carried through traction tests, rupture lengthening tests and permeability to the gas oxygen in the film of polyamide 6 and mechanical polyethylene, and assays, thermal analyses and scanning electronic microscopy in the blendes. It was also studied radiation dose (100 kGy) on the blends properties using an electron beam accelerator.
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Sayers, Paul William Charles. « Investigation of the structural changes in LDPE and XLPE induced by high electrical stress ». Thesis, Bangor University, 2001. https://research.bangor.ac.uk/portal/en/theses/investigation-of-the-structural-changes-in-ldpe-and-xlpe-induced-by-high-electrical-stress(c94eaa67-4ac2-4021-9f72-6347ca93fe6e).html.
Texte intégralRésumé :
High voltage electrical cables play an immensely important, although largely unseen, part in the lives of everybody in the world today. They are mostly buried underground and provide trouble free operation for the majority of their operational lives. However, the polymer based insulation that is used for a large number of high voltage cables is subject to long term ageing which can eventually lead to electrical breakdown. This ageing manifests itself as the appearance of tree like structures in the bulk polymer insulator. The growth of a tree frequently starts on the boundary of the polymer at the so-called "polymer-semicon" interface. This thesis is concerned, however, with the changes that must take place in the polymer before the tree is formed. Previous investigations of field induced changes occurring within polymer insulation have involved cutting the polymer to expose the region of interest: this is not a satisfactory as the cutting process can produce changes in the polymer. To avoid this a novel technique was developed whereby the polymer-semicon interface can be exposed without cutting the polymer. The interface region of the polymer in contact with the plane electrode was examined and even though the field in this region is less than at the point, it can be sufficiently large to induce structural change in the polymer, readily detectable by Raman spectroscopy. In studies of both LDPE and XLPE, we find evidence of structural change within the polymer and most significantly of considerable Raman fluorescence which is indicative of defect states in the polymer. The latter becomes modified as the polymer structure approaches electrical failure. The observations reported are set in context by the examination of the work of relevant authors and some conclusions deduced. The evidence supports a model in which the forces induced by the electrical field lead to failure by the mechanisms of local yield, microvoid craze and crack formation commonly invoked for the mechanical fracture of polymeric solids.
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Azevedo, Carolina Heitmann Mares. « Cinética plasmática e captação da associação de uma microemulsão rica em colesterol ao quimioterápico oleato de etoposideo em pacientes com câncer de ovário ». Universidade de São Paulo, 2004. http://www.teses.usp.br/teses/disponiveis/9/9136/tde-13042015-164832/.
Texte intégralRésumé :
Previamente foi relatado a associação do oleato de etoposídeo à uma microemulsão rica em colesterol (LDE) que é captada por células malignas que superexpressam receptores da Lipoproteína de Baixa Densidade (LDL). A associação do fármaco é estável, sua atividade antiproliferativa é preservada e há uma redução da toxicidade em animais. Dando continuidade, esse trabalho tem como objetivo investigar a cinética plasmática da associação LDE: oleato de etoposídeo e ainda verificar se a associação do fármaco à LDE modifica a propriedade da microemulsão de se concentrar nas células neoplásicas com aumento dos receptores, determinando a captação de ambos os componentes nos tecidos acometidos pelo tumor comparado com o tecido equivalente normal. O [3H]oleato de etoposídeo associado à LDE marcada radioativamente com [14C] oleato de colesterol, foi injetado intravenosamente em 14 pacientes com câncer de ovário (50,6 ± 7,5 anos), 24 horas antes da cirurgia. Amostras de sangue foram coletadas no período de 24 horas para determinar a curva de decaimento plasmático da associação. A radioatividade presente nas alíquotas do plasma foi determinada usando solução cintiladora e a Taxa Fracional de Remoção (TFR) foi calculada através de uma análise compartimental. Amostras de tecido ovariano com tumor e sem tumor foram coletadas durante a cirurgia, onde foi dado início ao procedimento de extração lipídica para determinação da radioatividade. A TFR da LDE e do oleato de etoposídeo foram similares (0,0881 e 0,1722 respectivamente, P= 0,2422). A média da captação tecidual de ambos[14C]-LDE e [3H]-oleato de etoposídeo por tecido maligno de ovário foi quatro vezes maior quando comparado com o tecido contralateral sem a doença (captação da LDE= 448 ± 184 e 143 ± 51 e a captação do oleato de etoposídeo foi de 346 ± 75 e 103 ± 56, respectivamente). O resultado indica que maior quantidade do fármaco fica retido na partícula da microemulsão, sendo removida da circulação e internalizada pelas células. Em adição foi mostrado que a associação LDE: oleato de etoposídeo teve habilidade de se concentrar nos tecidos malignos de ovário. Contudo, a associação pode ser usada para direcionar e concentrar o oleato de etoposídeo nas células malignas de ovário.Background: Previously we reported the association of etoposídeo oleate to a cholesterol-rich microemultion (LDE) that is taken up by malignant cells that overexpress low-density lipoprotein (LDL) receptors. The association of the drug is stable, preserves the anti-proliferative activity of the drug and reduces the toxicity to animals. In order to investigate the plasma kinetics of the association LDE:etoposídeo oleate and to verify whether the complex has the ability to concentrate in malignant ovarian cancer we performed the following analysis. Methods: [3H]etoposídeo oleate associated to LOE labeled with [14C]-Cholesteryl Oleate (CO) was intravenously injected into 10 patients with cancer of ovary (50,6 ± 7,5 yr.) 24 h before the surgery. Blood samples were collected over the 24 h period to determine the plasma decay curves of the complex labels. Radioactivity present in plasma aliquots was determined in a scintillation solution and the plasma fractional c1earance rate (FCR) was calculated by compartmental analysis. Specimens of tumors and normal ovaries excised during the surgery were collected for lipid extraction, separation by thin layer chromatography and radioactive counting. Results: Fractional clearance rate (FCR) of LDE and of the drug were similar (0,0881 e 0,1722, respectively, P =0.2422). The mean of the uptake of both [14C]-LDE and [3H]-etoposídeo oleate by malignat tissue of ovary was three fold greater when compared with that of the contralateral normal ovaries (LDE uptake = 448 ± 184 and 143 ± 51 and etoposídeo oleate uptake = 346 ± 75 and 103 ± 56, respectively). Conclusions: Our results indicate that most of the drug is retained in the microemulsion particles until its removal from the circulation and internalization by the cells. In addition, we showed that the association LDE:etoposídeo oleate has the hability to concentrate in malignant ovarian tissues. Therefore, the complex can be used to direct and concentrate etoposídeo against malignant ovarian cells.
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Prete, Ana Cristina Lo. « Transferência simultânea de lipídeos de um modelo artificial de lipoproteína (LDE) para a lipoproteína de alta densidade (HDL) ». Universidade de São Paulo, 2007. http://www.teses.usp.br/teses/disponiveis/9/9136/tde-23022015-145716/.
Texte intégralRésumé :
Lipoproteínas do plasma trocam lipídeos e apolipoproteínas constantemente. Além da ação de proteínas de transferência, a habilidade das lipoproteínas em receber ou doar lipídeos depende também de diversos outros fatores. A estrutura e a composição de lipídeos e de proteína das lipoproteínas podem influenciar a fluidez da partícula e, desse modo, esta habilidade da lipoproteína. No plasma, a classe de lipoproteína que é a mais afetada pela transferência de lipídeos é a HDL. O presente estudo foi projetado para estabelecer um método . simples para quantificar a habilidade desta lipoproteína em receber simultaneamente suas principais classes de lipídeos constituintes, fosfolipídeo, colesterol livre, éster de colesterol e triglicerídeo. O método é baseado na troca lipídica ocorrida entre uma nanoemulsão artificial (LDE) que se assemelha à estrutura lipídica da LDL, usada como doador de lipídeos radioativos, e as lipoproteínas plasmáticas. Após precipitação da LDE e das demais lipoproteínas, a capacidade da HDL de receber lipídeos é quantificada pela medida da radioatividade presente na lipoproteína. No presente estudo, foi realizada a padronização deste método, assim como analisadas possíveis interferências no método. No mesmo estudo, foi analisada a transferência de lipídeos da LDE para a partícula de HDL em indivíduos controles. A elevação da temperatura (4 a 37°C), do tempo de incubação (5min a 2h) e de HDL-Colesterol (33 a 244 mg/dL) resultaram em progressivo aumento na transferência dos quatro lipídeos da LDE para a HDL. Por outro lado, o aumento do pH (6,5 a 8,5) e da concentração de albumina (3,50 a 7,00 g/dL) não alteraram os valores de transferência. A amostra de plasma mostrou ser inalterada para este ensaio por período de 12 meses (p>0,05), enquanto que a LDE foi inalterada por até 15 dias (p>0.2). Os resultados da análise intra-ensaio apresentaram imprecisão (C.V.) para · a transferência de fosfolipídeo, colesterol livre, éster de colesterol e triglicerídeo de 0,83, 0,56, 1,49 e 0,51 %, respectivamente. A análise inter-ensaio mostrou imprecisão para os resultados de transferência de fosfolipídeo, colesterol livre, éster de colesterol e triglicerídeo 0,78, 0,59, 1,32 e 0,58%, respectivamente. A média da transferência de fosfolipídeo, colesterol livre, éster de colesterol e triglicerídeo da LDE para a HDL nos 53 voluntários foi de 25,5±2,6, 9,9±1 ,6, 4,8±1,3 e 6,9±1 ,1%, respectivamente. As transferências de éster de colesterol, triglicerídeo e colesterol livre se correlacionaram positivamente entre estes lipídeos. Foram encontradas correlações positivas também entre as transferências de fosfolipídeo e de triglicerídeo e entre a transferência de colesterol livre e a concentração de colesterol de HDL. O método de transferência de lipídeos para a fração HDL mostrou ser prático e preciso, .podendo, dentro das condições ideais estabelecidas neste trabalho, determinar a capacidade receptora de lipídeos da HDL.Plasma lipoproteins constantly exchange lipids and apolipoproteins. Besides the action of transfer proteins, the ability of lipoproteins to receive or donate lipids also depends on several other factors. The structure, lipid and protein composition of the lipoproteins may influence the fluidity of the particle and thereby this ability of lipoprotein. In the plasma, the lipoprotein class that is the most affected by lipid transfers is HDL. The current study was designed to establish a practical method to quantify the ability of this lipoprotein to simultaneously receive its main constituent lipid classes, namely phospholipid, free cholesterol, cholesteryl ester and triglycerides. The method is based on the lipids exchange between an artificial nanoemulsion (LDE) that resembles the LDL, used as a donor of radioactive lipids, and plasma lipoproteins. After precipitation of the LDE and the others plasma lipoproteins, the accept capacity of the HDL\' is quantified by the measure of radioactivity in the lipoprotein. In the present study, the validation of this method was carried through. Moreover, possible interferences in the method had been analyzed. In the same study, the transfer of lipids of LDE for the particle of HDL from control subjets was analyzed. The rise of temperature (4 to 37°C), time of incubation (5min to 2h) and of HDL-Cholesterol (33 to 244 mg/dL) resulted in gradual increase in the transfer of the four lipids from LDE to HDL. On the other hand, the increase of pH (6.5 to 8.5) and albumin concentration (3.50 to 7.00 g/dL) had not modified the values of transfers. The plasma sample showed to be unchanged for this assay for period of 12 months (p>0.05), whereas the LDE was unchanged for 15-days (p>0.2). The intra-assay results showed imprecision (C.V) of 0.83, 0.56, 1.49 and 0.51 % for phospholipid, free cholesterol, cholesteryl ester and triglycerides transfer, respectively. The inter-assay showed imprecision for results of phospholipid, free cholesterol, cholesteryl ester and triglycerides transfer of 0.78, 0.59, 1.32 and 0.58%, respectively. The average of phospholipid, free cholesterol, cholesteryl ester and triglycerides transfers from LDE to HDL in the 53 volunteers was of 25.5±2.6, 9.9±1.6; 4.8±1 .3 and 6.9±1 .1 %, respectively. Cholesterol ester, triglyceride and free cholesterol transfers positively correlated among each other. A positive correlation was also found between phospholipid and triglyceride transfers and free cholesterol transfer and HDL cholesterol concentration. The method of lipids transfer to HDL showed to be practical and reproducible, being able, inside of the ideal conditions established in this work, to determine the aceptora capacity of lipids of the HDL.
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Silva, Emanoel Pedro de Oliveira. « Estudos fotofísicos e fotobiológicos de sistemas de liberação contendo o fármaco fotossensível cloro-ftalocianina de alumínio para aplicação em terapia fotodinâmica ». Universidade de São Paulo, 2016. http://www.teses.usp.br/teses/disponiveis/60/60137/tde-21102016-112503/.
Texte intégralRésumé :
A terapia fotodinâmica (TFD) tem se apresentado nos últimos anos como uma alternativa para o tratamento de tumores cutâneos, viscerais e sistêmicos, demonstrando resultados promissores, tanto em estudos in vitro como in vivo. Trata-se de uma técnica simples e não invasiva. A terapia consiste na excitação de um fármaco fotossensibilizante por uma fonte de luz visível que depois de absorvida pela molécula, leva a produção espécies reativas de oxigênio (EROs) em presença do oxigênio molecular por uma sequencia de reações fotoquímicas. Nesse trabalho propõe-se a preparação, caracterização e detreminação da atividade fotodinâmica de uma nanoemulsão rica em colesterol e de lipossomas ultradeformáveis como novos sistemas de liberação para o fármaco fotossensibilizante cloro alumínio ftalocianina (PcAlCl), comparando com um sistema clássico de lipossoma convencional. Como modelo celular foram utilizadas células de glioblastoma (U87MG) e de melanoma (B16F10). As formulações apresentaram características desejáveis como reprodutibilidade, tamanho de partícula, estabilidade curto e em longo prazo e deformidade adequados para a utilização como meio de veiculação da PcAlCl. Pela análise dos estudos fotofísicos de rendimento quântico de fluorescência (?F), tempo de vida de fluorescência (?) e rendimento quântico de oxigênio singleto (??) da PcAlCl em etanol e incorporada nas formulações, pode-se observar que a incorporação a um veículo de liberação melhorou as características da PcAlCl. Nos estudos em células nenhum dos sistemas apresentou citotoxicidade na ausência de luz, mas apresentaram um aumento da atividade fotodinâmica da PcAlCl de até 80% quando comparadas à PcAlCl livre quando irradiadas. Todas as formulações apresentaram características que corrobora com o emprego como sistemas de liberação para o aumento da atividade fotodinâmica da PcAlCl podendo serem empregados no tratamento de glioblastoma e de melanomaThe Photodynamic therapy (PDT) has been an alternative for the treatment of skin, and brain tumors, and has shown promising results, both in vitro and in vivo, is a simple and non-evasive technique. The therapy consists into a light-sensitive drug excitation by a light visible source that once absorbed by the molecule lead to produce reactive oxygen species (ROS) in the molecular oxygen presence by a sequence of photochemical reactions. This work proposes the preparation and characterization of a cholesterol-rich nanoemulsion and ultradeformable liposomes as new delivery systems for the drug photosensitizer chloro aluminum phthalocyanine (PcAlCl) compared to a classical system as the conventional liposome and their photodynamic activity in glioblastoma cells line (U87MG) and melanoma cells line (B16F10). The formulations showed suitable characteristics such as reproducibility, particle size, short and long-term stability and deformity for their use as drug delivery for PcAlCl. For the photophysical studies: absorption, fluorescence, fluorescence quantum yield (?F), fluorescence lifetime (?) and quantum yield of singlet oxygen (??) of PcAlCl in ethanol and incorporated in the formulations demonstrated that the incorporation was able to improve its photophysical characteristics. In in vitro studies, the drug delivery systems showed no cytotoxicity in the absence of light, but demonstrated increased in PcAlCl photodynamic activity up to 80% over the PcAlCl free when irradiated. All formulations showed characteristics, which cooperates with the use of these drug delivery systems for, increased the PcAlCl photodynamic activity for glioblastoma and melanoma treatment
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Bulzaga, Stefano. « Studio dell'invecchiamento termico di LDPE utilizzato per i cavi in bassa tensione nelle centrali nucleari ». Master's thesis, Alma Mater Studiorum - Università di Bologna, 2018.
Trouver le texte intégralRésumé :
I sistemi di sicurezza e controllo delle centrali nucleari fanno affidamento sull’utilizzo di cavi in bassa tensione (I&C cables) i quali nel corso della loro vita operativa sono sottoposti a sollecitazioni di natura diversa. Le alte temperature e gli elevati livelli di radiazione causano infatti la degradazione dell’isolamento, costituito da materiale polimerico.. Per l’analisi del polimero si è scelta una temperatura di invecchiamento termico pari a 90°C, siccome questa risulta essere la tipica temperatura di lavoro dei cavi in bassa tensione all’interno delle centrali nucleari. L’invecchiamento termico è stato condotto in una stufa ad aria ed in una stufa da vuoto in maniera tale da mettere in evidenza le differenze in termini di fenomeni di degradazione ossidativa. L’analisi delle proprietà elettriche del polimero studiato sono state condotte mediante tecniche di spettroscopia dielettrica, la quale permette di determinare grandezze come la permettività immaginaria, correlata alle perdite dielettriche dei cavi.Sono state analizzate inoltre le proprietà meccaniche del LDPE attraverso prove di trazione effettuate con l’UTM (Universal test machine) del Dipartimento “Giacomo Ciamician” di Bologna così da ricavare grandezze come lo sforzo a rottura, il modulo di Young e l’allungamento a rottura in funzione del tempo di invecchiamento. Quest’ultimo, tra le proprietà meccaniche risulta essere uno dei migliori indicatori per la determinazione del grado di invecchiamento. Infine è stata realizzata anche una caratterizzazione chimica attraverso la realizzazione di una spettroscopia infrarossa IR in trasformata di Fourier (FTIR) per l’analisi delle variazioni di concentrazione dei diversi gruppi chimici, ed analisi di Oxidation Induction Time(OIT) per studiare il contributo dell’ossidazione, principale fenomeno di degradazione in ambiente atmosferico.
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Bourke, Alexandre. « Étude de la désorption thermique laser sur un dépôt de polytétrafluoroéthylène dans une source ionique LDTD ». Thesis, Université Laval, 2009. http://www.theses.ulaval.ca/2009/26290/26290.pdf.
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Malacart, Lorenzo. « Film di LDPE per uso agricolo additivati con una nuova NOR-HALS : produzione e studio di weathering ». Master's thesis, Alma Mater Studiorum - Università di Bologna, 2018. http://amslaurea.unibo.it/16721/.
Texte intégralRésumé :
Il progetto è un primo screening delle prestazioni di una nuova NOR-HALS. Sono stati settati due target a due anni in base alla contaminazione da zolfo e alla concentrazione di additivo. I campioni sono stati esposti in condizioni artificiali accelerate e outdoor. Gli agrofarmaci utilizzati sono stati zolfo sublimato, metamsodium e permetrina.
I dati riguardano la prima fase espositiva e risultano promettenti.
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Ramanujam, Maalolan [Verfasser], et Jörg [Akademischer Betreuer] Friedrich. « Photo-oxidation and weathering of LDPE studied by surface and bulk analysis / Maalolan Ramanujam. Betreuer : Jörg Friedrich ». Berlin : Universitätsbibliothek der Technischen Universität Berlin, 2013. http://d-nb.info/103128012X/34.
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Capone, Georgina. « Staff and service users' evaluations of therapeutic principles at a High Secure Learning Disability Therapeutic Community (LDTC) ». Thesis, University of Lincoln, 2017. http://eprints.lincoln.ac.uk/29721/.
Texte intégralRésumé :
Background: Growing evidence has been provided on the efficacy of Democratic Therapeutic Community (DTC) treatment in forensic LD populations (known as learning disability therapeutic communities, LDTC) in the form of reduced violence, personality pathology and interpersonal difficulties. Recently, the LDTC model has been introduced within a high secure setting at one of three high secure hospitals in the U.K., for males with a dual diagnosis of mild LD and PD, and produced equally successful results. While a number of outcome studies exist, on-going difficulties have remained in regard to applying a post-positivist approach to research design of Therapeutic Communities (TCs) as the approach fails to capture its matrix of interrelated treatment components. Consequently, there has been a call for investigation of processes within DTCs to identify important treatment mechanisms that support therapeutic change. While Haigh (2013) has updated the theoretical background on DTCs via formulating ‘quintessential principles’ within a given therapeutic environment the principles have not been empirically validated within a TC setting. Study aims: To explore service user and staff members’ evaluations of the quintessence principles as outlined by Haigh (2013) and identify whether any further important principles exist within the social climate of the LDTC that were not captured by current TC theory. Design: A single case study design was employed, with the ‘case’ being defined as the LDTC based at one of three high secure hospitals in the U.K. A qualitative approach was employed within the case study to enable initial analysis of TC members’ experience of therapeutic principles, any additional principles and to also permit identification of any shared experiences. The results of the qualitative analysis were used to develop a set of statements that can be used by future research to determine the importance of existing TC principles and additional elements identified in qualitative findings to TC members. Method: A qualitative approach was employed to enable analysis of TC members’ experience and evaluation of therapeutic principles in addition to identification of shared experiences. Data were collected via semi-structured interviews with 12 participants (6 staff members and 6 service users). The interview transcripts were initially analysed via deductive content analysis (Mayring, 2001) in order to identify whether Haigh’s (2013) quintessence principles were evident in the LDTC. Inductive thematic analysis (Braun & Clarke, 2006) was then performed on remaining data, which also involved completion of saliency analysis (Buetow, 2010) in the final stage to justify selection of themes and ensure identification of codes that did not recur but remained important to the research questions posed. Results: The deductive content analysis identified all five quintessence principles were experienced in the LDTC environment by staff and service users. Some limits to the principle of ‘agency’ were highlighted, with specific reference to difficulties implementing a flattened hierarchy in a forensic setting. Additional themes were identified via inductive thematic analysis and a saliency analysis indicated the following themes as both important and recurrent; security and risk, responsivity, trust, more physical freedom. Further themes that were identified as important but not recurrent within the saliency analysis included: staff fit with LDTC, moving on, being reflective. The theme of security and risk was specifically related to the context of the LDTC functioning in a high secure environment and ‘trust’ was understood to fall within Haigh’s (2013) conceptualization of the containment quintessence principle. While the remaining themes may not primarily contribute to the experience of secondary emotional development outlined by Haigh’s (2013) five quintessence principles they remain important considerations within therapeutic environments in light of their role in facilitating enactment of TC principles within secure environments, such as the LDTC. Conclusions: This is the first research paper that has attempted to test whether Haigh’s (2013) quintessence principles are evident within a given therapeutic community. The single case study provides empirical evidence for the quintessence principles in a novel TC setting along with further elements in the environment that help support implementation of quintessence principles. Fundamentally, the study suggests important recommendations for future research.
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Kodavati, Venkata Seshank, et Devi Prasad Buraga. « Study of Numerical Model Parameters and Crack Tip of a Packaging Materials ». Thesis, Blekinge Tekniska Högskola, Institutionen för maskinteknik, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:bth-13840.
Texte intégralRésumé :
Packaging industries widely use Low-Density Polyethylene (LDPE) in manufacturing different types of containers to store the food products. They are difficult to model numerically in order to have similar experimental response. This research deals with the study of numerical material model parameters of continuum LDPE. It is carried out with the help of experiments along with the numerical simulation of LDPE. Study of stress-strain distribution at crack tip and elements close to the tip is carried out in the LDPE material with the pre-existing center crack with varying lengths. By implementing an optimization algorithm and automating the simulation with the help of python code, we obtain a set of parameters. This obtained data for the material can be used directly for numerical simulation in the future without carrying out additional experimental studies. After implementing the optimization algorithm is also validated, against the results that were close to the experimental response.
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Miranda, Gabriela Messias. « Avalia??o do comportamento de degrada??o de Blenda de PEBD com aditivo PEPZYME(TM) ». Pontif?cia Universidade Cat?lica do Rio Grande do Sul, 2017. http://tede2.pucrs.br/tede2/handle/tede/7767.
Texte intégralRésumé :
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Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior - CAPES
Low density polyethylene (LDPE) was mixed with the PEPZYMETM commercial additive in order to prepare a blend with biodegradation behavior, therefore was added 8% of the commercial additive (PE8), once that the PE is a material of high resistance to degradation. Due to this property, processability and low cost, LDPE is a plastic very used in various applications, mostly in packaging. Beside biodegradation, it is important evaluate your abiotic degradation. For that, it was realized a accelerated aging assay for 1000 h with cycles of 8h of UVA radiation in 60 ?C and cycles of 4 h of condensation in 50 ?C, to evaluate the behavior of this material front weathering. After the pure PE samples (PE0) and with additive were removed to each 200h and characterized, in order to identify the changes in the chemical properties, physical, mechanical, thermal and morphological, caused through the additive effect as well as weathering effect. The results of this study showed that the aging provoke changes in the structural characteristics (insertion of functional groups) and morphological (appearance of microcracks and increase of th roughness), mechanical (increase of the stiffness and loss of plasticity) and thermal (increase of the crystallinity degree and of the range of thermal degradation) properties; being this changes very attractive for the microorganisms when the exposed materials were put in contact with the soil. The presence of the additive in the PE matrix helped in the aging process, once that functional groups were added in the chemical structure of LDPE. The C, H, N contents and carbonyl indexes of the samples were of according with the FTIR spectrums. The C:N ratios of PE8 and PE8/env presented the expected behavior in the literature (decrease of this value) for the occurrence of decomposition process.
Polietileno de baixa densidade (PEBD) foi misturado com o aditivo comercial PEPZYMETM a fim de preparar uma blenda com comportamento de biodegrada??o, para tanto foi adicionado 8% do aditivo comercial (PE8), uma vez que o PE ? um material de alta resist?ncia a degrada??o. Devido a esta propriedade, processabilidade e seu baixo custo, o PEBD ? um pl?stico muito utilizado em diversas aplica??es, principalmente em embalagens. Al?m da biodegrada??o, ? importante avaliar ? sua degrada??o abi?tica. Para isso foi realizado um ensaio de envelhecimento acelerado durante 1000 h com ciclos de 8 h de radia??o UVA a 60 ?C e de 4 h de condensa??o a 50 ?C, para avaliar o comportamento deste material frente ao intemperismo. Ap?s, as amostras de PE puro (PE0) e com aditivo, foram retiradas a cada 200 h e caracterizadas, a fim de identificar as altera??es nas propriedades qu?micas, f?sicas, mec?nicas, t?rmicas e morfol?gicas, causadas pelo efeito do aditivo bem como pelo efeito do intemperismo. Os resultados deste estudo mostraram que o envelhecimento provoca altera??es nas caracter?sticas estruturais (inser??o de grupos funcionais) e nas propriedades morfol?gicas (aparecimento de microfissuras e aumento da rugosidade), mec?nicas (aumento da rigidez e perda de plasticidade) e t?rmicas (aumento da cristalinidade e do intervalo de degrada??o t?rmica), sendo estas altera??es muito atraentes para os microrganismos quando os materiais expostos s?o colocados em contato com o solo. A presen?a do aditivo na matriz de PE ajudou no processo de envelhecimento, uma vez que foram adicionados grupos funcionais na estrutura qu?mica do PEBD. Os Teores de C, N, H e os ?ndices de carbonila das amostras estavam de acordo com os espectros de FTIR. A raz?o C/N de PE8 e PE8/env apresentou o comportamento esperado na literatura (redu??o deste valor) para ocorr?ncia do processo de decomposi??o.
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Bulgarelli, Adriana. « Uso de metotrexato associado à nanopartícula rica em colesterol (LDE) para tratamento da aterosclerose ». Universidade de São Paulo, 2010. http://www.teses.usp.br/teses/disponiveis/9/9136/tde-24052010-162400/.
Texte intégralRésumé :
O Metotrexato (MTX) é um fármaco utilizado como anti-inflamatório no tratamento da artrite reumatóide (AR). O risco de doença cardiovascular em pacientes com AR é menor quando tratados com MTX. Apesar dessa evidência, há poucos relatos da utilização de MTX para o tratamento da aterosclerose. Foi desenvolvida em nosso laboratório uma nanopartícula rica em colesterol (LDE), a qual é reconhecida pelos receptores da lipoproteína de baixa densidade (LDLr) após injeção na corrente sangüínea. A LDE concentra-se em células com hiperexpressão de LDLr, em processos proliferativos como a aterosclerose. Dessa maneira, a LDE pode ser utilizada como veículo para o direcionamento de fármacos contra essas células. A molécula de MTX foi latenciada e a modificação do fármaco aumentou a sua incorporação à LDE. A proposta desse estudo foi avaliar a eficácia de MTX associado à LDE (LDE-MTX) no tratamento da aterosclerose em coelhos além de investigar o efeito desse complexo na expressão de genes inflamatórios que participam do processo aterogênico. Para realização do estudo foram utilizados quatro grupos de 10 coelhos (raça New Zealand) cada, sendo que todos foram submetidos a uma dieta rica em colesterol por 8 semanas. Após as primeiras 4 semanas de dieta, os grupos foram tratados com LDE-MTX (grupo LDE-MTX), MTX comercial (grupo MTX comercial), LDE (grupo controle LDE) ou solução salina (grupo controle Salina), via endovenosa por 4 semanas. O grupo LDE-MTX não apresentou toxicidade ao longo do tratamento de acordo com os parâmetros utilizados, enquanto que o grupo MTX comercial apresentou uma queda acentuada de eritrócitos ao final do tratamento (p<0,001). A análise morfométrica macroscópica mostrou que os grupos LDE-MTX e MTX comercial reduziram as lesões ateroscleróticas quando comparados ao grupo controle Salina (66 e 76%, respectivamente) (p<0,001). Por microscopia, a camada íntima do arco aórtico e torácico foi reduzida nos grupos LDE-MTX (67% e 75%) e MTX comercial (81% e 92%, respectivamente) quando comparados com os mesmos fragmentos do grupo controle Salina (p<0,05). A presença de macrófagos na camada íntima dos grupos LDE-MTX e MTX comercial foi reduzida em 59% e 57% (p<0,001) no arco aórtico e 37% e 38% na região da aorta torácica (p=0,016) em relação ao grupo controle Salina, respectivamente. A porcentagem de MMP-9 no arco aórtico foi reduzida em 48% em ambos os grupos tratados (p=0,0003), enquanto que na aorta torácica LDE-MTX e MTX comercial diminuíram 54% e 66% (p<0,0001) respectivamente, em relação ao grupo controle Salina. Na região da aorta abdominal, a redução de MMP-9 também foi observada nos grupos LDE-MTX (68%) e MTX comercial (70%) (p=0,016). Quando se comparou ao grupo controle LDE, os dois grupos tratados tiveram porcentagens semelhantes de redução em todas as análises morfométricas. Nos estudos de expressão gênica in vivo, 5 genes inflamatórios se mostraram hipoexpressos (TNF-α, MCP-1, IL-1β, IL-18 e MMP-12) e um gene (IL-10) apresentou aumento de expressão no arco aórtico de coelhos tratados com LDE-MTX em relação ao grupo controle. No experimento in vitro, 5 dos 10 genes (TNF-α, VAP-1, IL-1β, CXCL2 e TLR2) avaliados tiveram redução da expressão e 1 (TGF-β1) se mostrou hiperexpresso na linhagem de endotélio humana (HUVEC) tratada com as duas formulações de MTX. Os resultados indicam que tanto a LDE-MTX quanto MTX comercial reduzem acentuadamente as lesões ateroscleróticas em coelhos e parecem minimizar a resposta inflamatória na doença aterosclerótica. Contudo, LDE-MTX apresentou uma tolerabilidade maior ao tratamento, pois não apresentou toxicidade hematológica em comparação com MTX comercial.Methotrexate (MTX) is the most frequently used drug for rheumatoid arthritis treatment. The incidence of vascular disease in these patients is lower when treated with MTX. However, few studies have been done using MTX for atherosclerosis treatment. In previous studies, we showed that, after injection into blood stream, a cholesterol-rich nanoparticle (LDE) binds to low density lipoprotein receptors (LDLr) and concentrates in tissues with intense cell proliferation such as atherosclerosis. LDE may thus carry drugs directed against those tissues reducing the toxicity of chemotherapeutic agents. For stable association with LDE, a lipophylic methotrexate derivative was used. The purpose of this study was to test MTX associated to LDE (LDE-MTX) in rabbits with atherosclerosis and investigate their anti-inflammatory effects on inflammatory mediators. Atherosclerosis was induced in rabbits by cholesterol rich diet during eight weeks. After 4 weeks from the introduction of the atherogenic diet, 4 groups of 10 animals were treated with LDE-MTX (LDE-MTX group), commercial MTX (commercial MTX Group), LDE (LDE control group) and saline solulion (Saline control group). MTX dose in both preparations was 4mg/kg/week during 4 additional weeks. LDE-MTX group showed superior tolerability with pronouncedly lesser hematologic toxicity in comparison to commercial MTX (p< 0.001). By morphometric analysis, both LDE-MTX and commercial MTX treatment groups showed a pronounced reduction of lesion area compared with Saline control group (66-76% respectively) (p<0001). By microscopy, intimal width at aortic arch and thoracic segments was reduced by 67% and 75% in LDE-MTX group compared to Saline control group, respectively (p<0.05). Commercial MTX group showed a reduction of 81% and 92% at aortic arch and thoracic segments compared to Saline control group, respectively (p<0.05). Presence of macrophages in intima layer at aortic arch was reduced by 59% and 57% (p<0.001) in LDE-MTX and commercial MTX groups while at thoracic segments was diminished by 37% and 38% (p=0.016) compared to Saline control group, respectively. MMP-9 percentage was diminished by 48% in both treated groups at aortic arch (p=0.0003) while at thoracic segment, LDE-MTX and commercial MTX reduced by 54% and 66% (p<0.0001) compared to Saline control group, respectively. Furthermore, MMP-9 percentage also diminished at abdominal segment in LDE-MTX group (68%) and commercial MTX (70%) when compared to Saline control group (p=0,016). When compared to LDE control group, both treated groups had similar percentage reduction in all morphometric analysis. In vivo studies, the expression of 5 inflammatory genes was downregulated (TNF-α, MCP-1, IL-1β, IL-18 and MMP-12) and 1 was upregulated (IL-10) when rabbits with induced atherosclerosis were treated with LDE-MTX. Besides, 5 inflammatory genes were downregulated (TNF-α, VAP-1, IL-1β, CXCL2 e TLR2) and 1 was upregulated (TGF-β1) when human endothelial cell line (HUVEC) was treated with both MTX preparations. Therefore, MTX can be an effective drug for atherosclerosis treatment and associated to LDE, side effects of this chemotherapeutic agent can be minimized.
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shahen, mohamed. « Development of a Nakajima test and its potential variants setup on thin flexible LDPE film and Aluminum foil ». Thesis, Blekinge Tekniska Högskola, Institutionen för maskinteknik, 2019. http://urn.kb.se/resolve?urn=urn:nbn:se:bth-19007.
Texte intégralRésumé :
The thesis aimed to identify fracture strain for multiaxial loading for laminate material of Al and LDPE that is mostly used in the food packing technology specially in liquid packaging industry. These materials are thin and flexible which make it difficult to handle and test it. The investigation was through applying new Nakajima test setup on such a material by designing a custom setup and 3D printing the Nakajima setup prototype to be able to use it in this study. DIC technique was used to get the results from the Nakajima test and the software used to apply the DIC technique is GOM correlate. As a validation for measurement from such a technique, a tensile test has been done and measured strains were compared with those from the specimen from the Nakajima that has smallest width as it was close to a uniaxial loading. One more validation technique was by creating a FE-model using (Abaqus software) for the biaxial loading and comparing it to the biaxial loading results that obtained from the DIC analysis.
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Gomes, Almir Anacleto de Araujo. « A epêntese vocálica inicial em clusters sC por aprendentes brasileiros de inglês como LDE ». Universidade Federal da Paraíba, 2014. http://tede.biblioteca.ufpb.br:8080/handle/tede/6429.
Texte intégralRésumé :
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Previous issue date: 2014-02-24Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES
This study aims to describe the variable process of inserting the epenthetic vowel [ɪ] in words beginning with clusters at onset position in English by Brazilian, from Paraíba, learners of English so called foreign language. Based on research conducted regarding this phenomenon as: Escartín (2005) with Hispanic learners of English so called foreign language and similar phenomena Cardoso (2004, 2008, 2009). The objective of this research is, then, to identify the incidence frequency of the insertion of vowel epenthesis at onset position of words in English that begin with one of the following clusters /sp/, /st/, /sk/, /sl/, /sm/, and /sn/ by Brazilian learners of English so called foreign language. This work aims to answer the following guiding questions: what is the incidence frequency of the onset vowel epenthesis in sC cluster in English by Brazilian learners of English so called foreign language?; what is the role of the sonority of the second consonant of the cluster and the preceding phonological context on the occurrence of onset vowel epenthesis in sC cluster?; what is the role of the learner's proficiency, and level of output formality in the occurrence of onset vowel epenthesis in sC cluster? and what is the role of the English so called foreign language learner phonological awareness in the occurrence of onset vowel epenthesis in sC cluster? The hypothesis are that obstruent and liquid consonants can promote vowel epenthesis, whereas nasal ones do not favor it; that preceding consonantal and pause environments favor initial vowel epenthesis while preceding vowel epenthesis do not favor such occurrence; that the more proficient is the informant in the target language, the less use of initial vowel epenthesis in sC clusters; and the more formal is the data collection style less initial vowel epenthesis in sC clusters happens. The research corpus is composed of 18 informants from Paraiba, learners of English so called foreign language, distributed in basic, intermediate and advanced levels of proficiency. For speech data collection was recorded twenty-eight sentences and text in English read by the participants. The collected material was quantitatively analyzed by the computer program GOLDVARB X (Sankoff, Tagliamonte and Smith, 2005). The independent variables are learner s level of proficiency and phonological awareness in the so called foreign language, sonority of the second element of the cluster, preceding phonological context and instrument type of data collection. The statistical analysis shows, in decreasing order of significance, that the sonority of the cluster, the learner s level of proficiency, the learner s phonological awareness, and the preceding context of the cluster are the variables more relevant to the realization of onset vowel epenthesis in sC cluster. The achieved results contribute not only to understand how English so called foreign language learning occurs by Brazilian learners, but also promotes pedagogical implications for teaching English so called foreign language.
epentética em palavras iniciadas por cluster em posição inicial na língua inglesa por aprendentes brasileiros, do estado da Paraíba, de inglês como língua dita estrangeira, tendo como base pesquisas realizadas a respeito desse fenômeno como: Escartín (2005) com aprendentes hispânicos de inglês como LDE e fenômenos semelhantes Cardoso (2004, 2008, 2009). O objetivo dessa pesquisa é, então, identificar a frequência da ocorrência de inserção da epêntese vocálica ou vogal de apoio na posição inicial das palavras em língua inglesa que se iniciam com um dos seguintes clusters /sp/, /st/, /sk/, /sl/, /sm/, e /sn/ por aprendentes brasileiros de inglês como LDE. Este trabalho tem como meta responder às seguintes perguntas norteadoras: qual a frequência de ocorrência da epêntese vocálica inicial em cluster sC em L2 por aprendentes brasileiros de inglês como LDE?; qual o papel da sonoridade da segunda consoante do cluster e do contexto fonológico precedente na ocorrência de epêntese vocálica inicial em cluster sC?; qual o papel da proficiência do aprendente, e nível de formalidade da produção na ocorrência de epêntese vocálica inicial em cluster sC?; e qual o papel da consciência fonológica do aprendente de inglês como LDE na ocorrência de epêntese vocálica inicial em cluster sC? As hipóteses são que as consoantes obstruintes e líquidas possam favorecer a epêntese vocálica, enquanto que as consoantes nasais não favoreçam; o contexto fonológico precedente consonantal e de pausa favoreçam a epêntese vocálica inicial em clusters sC, ao passo que o contexto vocálico precedente desfavoreça a ocorrência de tal fenômeno; quanto mais proficiente na língua alvo for o informante, menos se utilize da epêntese vocálica inicial em cluster sC; e quanto mais formal for o tipo de coleta de dados, menos aconteça o fenômeno da epêntese vocálica em cluster sC. O corpus da pesquisa é constituído por 18 informantes paraibanos, aprendentes de inglês como LDE, pertencentes aos níveis de proficiência na LDE: básico, intermediário e avançado. Para a coleta dos dados de fala foi gravada a leitura de vinte e oito frases e um texto em inglês. O material coletado foi analisado quantitativamente através do programa computacional GOLDVARB X (SANKOFF; TAGLIAMONTE; SMITH, 2005). As variáveis independentes observadas são: nível de proficiência e consciência fonológica do aprendente, sonoridade do segundo elemento do cluster, contexto fonológico precedente e tipo de instrumento de coleta de dados. O tratamento estatístico realizado mostra, em ordem decrescente de significância, que as variáveis sonoridade do cluster, nível de proficiência, consciência fonológica do informante, contexto precedente ao cluster são as que se mostram mais relevantes à realização da epêntese vocálica inicial em cluster sC. Os resultados alcançados contribuirão não só para entender como ocorre a aprendizagem de inglês como LDE por aprendentes brasileiros, mas promove também implicações pedagógicas no ensino de inglês como LDE.
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Landes, Jasmin K. « Hemispheric differences in the temporal updating in short narrative situation models using a LDT ». Thesis, Landes, Jasmin K. (2011) Hemispheric differences in the temporal updating in short narrative situation models using a LDT. Honours thesis, Murdoch University, 2011. https://researchrepository.murdoch.edu.au/id/eprint/10608/.
Texte intégralRésumé :
Recent research into situation model representations has demonstrated the neglect of the temporal dimension relative to the remaining dimensions that govern the formation of situation model representations. Furthermore, literature has recently demonstrated right hemisphere (RH) involvement in the processing, integrating and revising of semantic information. For the purpose of gaining a cohesive understanding of situation models and the mechanisms involved in their formation, the present study aimed to investigate whether the RH hosts at least the temporal dimension of situation model representations. Thirty-four right-handed psychology students from Murdoch University participated in a computerised go-nogo lexical decision task (LDT) in which participant reaction time and error rates were documented. Temporal shifts in situation model representations were controlled for by presenting participants with short narrative passages that included short or long temporal adverbials or none at all during baseline/ neutral condition. Words and non-words were projected to the left visual field (LVF)/RH, the central visual field (CVF) and the right visual field/ left hemisphere (RVF/LH). Contrary to the hypotheses, the results did not demonstrate any temporal shifts for targets presented to the CVF or LVF/RH, as the degree of facilitation of targets between the short and long temporal references did not vary significantly. These findings are contrary to Zwaan’s (1996) strong iconicity assumption as well as previous behavioural research to suggest temporal updating. Nonetheless, compelling theoretical support lead to the continued maintenance of the claim that temporal awareness is inherent to the LVF/RH.
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Dungner, Karin, Ebba Eskner, Amanda Holst, Nina Petersson, Maria Pokosta et John Eric Roos. « Accelerated aging of cellulose-based composites in different climate environments : A project provided by Biofiber Tech Sweden AB ». Thesis, Uppsala universitet, Institutionen för kemi - Ångström, 2021. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-444877.
Texte intégralRésumé :
This paper reviews the effects of accelerated aging with increased humidity and temperature on cellulose-based composites. The composites consist of a matrix of plastic reinforced with cellulose fibers. The company Biofiber Tech Sweden AB provided four different composites and a conventional polyolefin as reference. The aim was to examine changes in mechanical properties, chemical composition and appearance after aging, as well as variations between materials. Two different climate conditions were tested, 85% RH and <10% RH, both in 90℃. A climate chamber and an oven were used to create the extreme environmental conditions. To analyze the results, tensile testing and FTIR were performed, and color intensity and density were measured. All samples decreased in color intensity throughout aging, and dark irregularities appeared on some of the samples exposed to high humidity, which may be due to fungal formation. The tensile testing showed a general difference between high and low RH and the toughness showed a tendency to decline with aging in high humidity for many samples. The FTIR measurements also did not show any general trend. To improve the study, it would be desirable to age the material for a longer time and at a higher temperature. Overall, more samples and measurements within each characterisation technique would be needed to achieve more reliable results. Nevertheless, this study hopes to be a starting point for further research on the long-term durability of Biofiber Tech’s composites.
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Camprini, Angela. « Caratterizzazione e modellazione della distribuzione di carica di spazio in LDPE nanoaddittivato con ossido di grafene per applicazioni HVDC ». Master's thesis, Alma Mater Studiorum - Università di Bologna, 2017. http://amslaurea.unibo.it/13362/.
Texte intégralRésumé :
In questo elaborato viene analizzato l’accumulo di carica di spazio in nanocompositi in LDPE additivato con nanoparticelle di ossido di grafene, al variare della concentrazione di filler impiegata. La carica di spazio è stata valutata mediante il metodo PEA, il cui sistema è stato prima ottimizzato ed automatizzato. Le prove sono state svolte a due livelli di tensione applicata, 40 kV/mm e 60kV/mm, e a tre temperature, 20°C, 40°C e 60°C. Il minor accumulo di carica di spazio, e conseguentemente la minor distorsione del campo elettrico, è stato ottenuto con una concentrazione di filler pari allo 0.05% in peso, per entrambe le tensioni applicate. È stato quindi creato un modello geometrico che correlasse l’andamento dell’accumulo di carica di spazio al variare della concentrazione di nanoadditivo nei provini, a tal fine sono state utilizzate le teorie riguardanti l’interfase. Confrontando i risultati ottenuti dalle simulazioni con i risultati sperimentali è stato ipotizzato che un'eccessiva interfase possa ridurre l’effetto barriera che l’ossido di grafene crea agli elettrodi e favorire il trasporto di carica all’interno del materiale. Per questo motivo nell’uso di ossido di grafene come nanoadditivo sono sufficienti percentuali basse per ottenere buoni materiali dielettrici nanocompositi.
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Punnam, Pradeep Reddy, et Chitendar Reddy Dundeti. « A Finite Element Analysis of Crack Propagation in Interface of Aluminium Foil - LDPE Laminate During Fixed Arm Peel Test ». Thesis, Blekinge Tekniska Högskola, Institutionen för maskinteknik, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:bth-14100.
Texte intégralRésumé :
This thesis deals with numerical simulation of a peel test with an Aluminium foil and Low Density Poly-Ethylene (LDPE) laminate. This work investigates the effects of the substrate thickness and studies the influences of interfacial strength and fracture energy of the cohesive zone between the Aluminium and LDPE. This study evaluates the proper guidelines for defining cohesive properties. A numerical cohesive zone model was created in ABAQUS. Continuum tensile tests were performed to extract LDPE material properties. The aluminium properties were found in literature. After acquiring material parameters, the simulation continued with studying the effects of changing interfacial strength, geometric parameters and fracture energy. The results were obtained in the form of root rotations and the force displacement response was studied carefully. It was validated by comparison to the traction separation curve.
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Moura, Juliana Ayello. « Uso de uma nanoemulsão rica em colesterol (LDE) como veículo para o di-dodecil metotrexato ». Universidade de São Paulo, 2007. http://www.teses.usp.br/teses/disponiveis/5/5136/tde-12092008-134509/.
Texte intégralRésumé :
O uso da LDE como veículo para quimioterápicos tem mostrado ser uma boa estratégia para aumentar a eficácia terapêutica dos mesmos. Nesse estudo, a LDE foi empregada como veículo para um derivado lipofílico do metotrexato (MTX), o di-dodecil metotrexato, que foi obtido com rendimento elevado através de reação de esterificação do MTX. O aumento na lipofilicidade do derivado possibilitou incorporação na LDE com rendimento e estabilidade elevados. O IC50 de LDE-di-dodecil MTX foi cerca de 100 vezes menor em relação ao MTX comercial, sua captação celular mais elevada nas linhagens leucêmicas estudadas e sua toxicidade animal reduzida, mostrando que a LDE é um veículo promissor para este fármaco.The use of LDE as vehicle to drugs is a great strategy to improve the therapeutic index and reduce the side effects. In this study LDE was used as vehicle to di-dodecyl methotrexate, a lipophilic derivative of MTX, obtained through an esterification reaction with a high yield. The increased lipophilicity of the derivative allowed a high association to LDE and good stability. The IC50 of LDE-di-dodecyl MTX was lower than that of the MTX and the uptake was higher in leukemic cells. The MTX toxicity in mice was reduced after association to LDE, showing that LDE is a promising vehicle to this drug.
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Ruiz, Jorge Luis Maria. « Caracterização de uma nanopartícula lipídica semelhante à LDL (LDE) como vetor para RNA de interferência ». Universidade de São Paulo, 2011. http://www.teses.usp.br/teses/disponiveis/5/5167/tde-14062011-154226/.
Texte intégralRésumé :
As nanopartículas são consideradas promissores vetores para a liberação eficaz e segura de ácidos nucléicos para tipos específicos de célula ou tecido, proporcionando uma alternativa aos vetores virais para terapia gênica. No entanto, com a maioria destes sistemas não torna possível a entrega de oligonucleotídeos nas células in vivo de forma especifica. O uso de uma nanoemulsão funcionalmente semelhante à lipoproteina de baixa densidade poderia resolver esse problema, pois esta particula é capaz de direcionar o transporte das moléculas para a internalização celular através de receptores de LDL. Aqui, descreve-se um sistema lipidico semelhante à lipoproteína de baixa densidade, LDE, capaz de direcionar e liberar RNA de interferência (RNAi) para as células tumorais in vitro e in vivo em um modelo celular que expressa resistência a múltiplas drogas (células de sarcoma uterino; MESSA/ Dx5). Estudou-se também as caracteristicas de captação do complexo LDE-RNAi e a regulação especifica do gene mdr-1. Os resultados sugerem que a LDE é estavel e liga-se com alta afinidade aos RNAis permitindo que eles entrem nas células tumorais, com localização citoplasmática. Em conclusão, a LDE, por direcionar o RNAi a receptores de LDL favorece o silenciamento do gene mdr-1 por RNAi nas células MES-SA/Dx5 aumentando sua sensibilidade a quimioterápicosNanoparticles are considered promising vectors for efficient and safe delivery of nucleic acids to specific types of cell or tissue, providing an alternative to viral vectors for gene therapy. However, most of these systems cannot target and deliver oligonucleotides to specific cells in vivo. The use of nanoemulsion functionally resemble low density emulsion could solve this problem, once particle is capable of direct the molecules transport to the cell through internalization in LDL receptors. Here, we describe a lipid system similar to low density lipoprotein, LDE, capable of targeting and release small interfering RNA (siRNA) to tumor cells in vitro and in vivo in a cell model that expresses multidrug resistance (sarcoma uterine cell line; MES-SA/Dx5). Were also studied the characteristics of uptake of the complex LDE-siRNA, as well as the downregulation of mdr-1 gene. The results suggest that LDE is stable and bind with high affinity to siRNAs allowing them to enter tumor cells, with cytoplasmic localization enhanced. In conclusion, LDE, binds to siRNA through LDL receptors, and promotes mdr-1 silenciament by RNAi in MES-sa/Dx5 cells, increasing their sensitivity to chemotherapeutics agents
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Cerqueira, Mario Henrique de. « Processamento do compósito LDPE/Al proveniente da reciclagem de embalagens cartonadas e desenvolvimento de suas modificações com fibras de madeira ». Universidade Federal de São Carlos, 2006. https://repositorio.ufscar.br/handle/ufscar/754.
Texte intégralRésumé :
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Previous issue date: 2006-02-10The urban solid waste problem has been one of the biggest environmental challenges these days. The solution to this problem lies in integrated waste management, the objective is to minimize volumes sent to landfills. Recycling is a big part of this waste management process which involves the reprocessing of materials to obtain alternative uses for these materials in every day life. One of the solid waste materials sent for recycling is the carton package, which is made of paper, polyethylene and aluminum. In conjunction with this, the search for new plastics compounds reinforced with cellulose fibers has been appointed as a market demand, thanks to the high number of possible applications of these materials, for instance, in the car manufacturing industry, civil construction, etc. In this study the modification of the low density polyethylene/aluminum from carton packages reinforced with cellulose fibers is investigated, and the addition of the grafted copolymer with maleic anhydride, acting as a compatibilizer, whose main target is to add value to the material produced, making them more attractive from a market point of view. Grafted copolymer was added to the LDPE/Al composite and the posterior extruded. Cellulose fibers, in different percentages and particle sizes, were mixed with the resulting material from the first extrusion, and the posterior extruded in sheets, with different properties and aspects. After processing, the obtained materials were applied to thermical and mechanical characterization, infrared spectroscopy and surface eletronic microscopy to verify the efficiency of the modifications. This research showed us that by increasing the cellulose fiber percentages in the generated composites incremented mechanical properties and thermical stability in comparison to the original composite, and indicated a subtle action of the compatibilizer in the used experimental conditions.
A problemática dos resíduos sólidos urbanos tem sido uma das grandes questões ambientais atualmente. Para solução deste problema surge o gerenciamento integrado de resíduos, que tem como objetivo a minimização dos volumes enviados para aterros sanitários. A reciclagem é parte deste gerenciamento, onde se reprocessam materiais, para obtenção de materiais alternativos presentes da vida cotidiana. Um dos resíduos sólidos enviados para a reciclagem é a embalagem cartonada, composta por papel, polietileno e alumínio. Aliado a este fato, a busca por novos compostos plásticos reforçados com fibras celulósicas tem-se apresentado como uma demanda de mercado, devido ao alto número de aplicações possíveis para estes materiais, como, por exemplo, na indústria automotiva, construção civil e outras mais. Assim, neste estudo procurou-se investigar a modificação do compósito polietileno de baixa densidade / alumínio proveniente de embalagens cartonadas através do reforçamento com fibras celulósicas, e adição de copolímero graftzado com anidrido maleico, que age como compatibilizante, de forma a agregar-se valor comercial ao material produzido, tornando-o mais atrativo do ponto de vista mercadológico. Os compósitos elaborados foram gerados através de duas diferentes extrusões. Ao compósito PE/Al adicionou-se o copolímero graftzado, e estes foram posteriormente extrudados. As fibras celulósicas, em diferentes teores e com diferentes tamanhos de partículas, foram misturadas ao material resultante da primeira extrusão, e assim posteriormente extrudadas, em segunda etapa, na forma de lâminas, com diferentes propriedades e aspectos resultantes. Aos compostos obtidos ao final do processamento foram realizadas caracterização térmica, mecânica, espectroscopia de infravermelho e microscopia eletrônica de varredura visando verificar a eficácia destas modificações. Esse trabalho mostrou que o aumento dos teores de fibras celulósicas nos compostos produzidos proporcionou incremento das propriedades mecânicas e de estabilidade térmica em relação ao compósito original, além de indicar uma sutil ação do compatibilizante utilizado, nas condições experimentais empregadas.
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Sisli, Zekiye. « Degradable Mulch Films For Agricultural Purposes ». Master's thesis, METU, 2012. http://etd.lib.metu.edu.tr/upload/12615022/index.pdf.
Texte intégralRésumé :
The plastic mulch films, which are mostly made from LDPE, are used in order to increase the yields and to prevent the weed growth by covering the top of the soil by leaves or straw in nature. After a period, the mulch films turn into unmanageable quantities of soiled plastic films, which cause an environmental problem. Using degradable mulch films for agricultural purposes can be a solution for the environmental problems caused by the plastic mulch films.
In this study, to introduce biodegradability to mulch films, a natural biopolymer starch was used. Before blending, starch was transformed into thermoplastic starch in order to make the starch processable. The need, to provide adhesion and interaction between thermoplastic starch and LDPE, citric and stearic acid were considered as compatibilizers. To accelerate the degradation of the LDPE matrix, three pro-oxidants cobalt(II) acetylacetonate, iron(III) stearate and manganase(II) stearate were used.
The films prepared were characterized by FTIR spectroscopytheir thermal and mechanical properties were analyzed and buried under soil. The films recovered from soil after 76 days were characterized by FTIR spectroscopy, their weight loss were measured and their thermal and mechanical properties were analyzed. Studies showed that the use of cobalt(II) acetylacetonate gave improved results in terms of the mechanical properties and thermal stabilities of the films. Additionally, it is observed that the use of citric acid as a compatibilizer improved the thermal stabilities of starch in the films. Lastly, it is observed that the mechanical properties of the films were affected by the interactions between compatibilizers and pro-oxidants.
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Souza, Marcos Rogério de. « Blenda de poli (tereftalato de etileno) com polietileno de baixa densidade ». Universidade de São Paulo, 2007. http://www.teses.usp.br/teses/disponiveis/3/3133/tde-03062008-173546/.
Texte intégralRésumé :
Neste Trabalho foi preparada e estudada a blenda de poli(tereftalato de etileno) (PET) com polietileno de baixa densidade (PEBD). Esta blenda apresenta interesse científico e tecnológico decorrente da possibilidade de associar as propriedades de resistência térmica e elevado módulo de elasticidade do PET à boa resistência à fratura e à flexibilidade a baixas temperaturas do PEBD. Duas séries de misturas contendo diferentes proporções de PET:PEBD foram preparadas através de mistura em fusão numa extrusora dupla-rosca, contendo como agente compatibilizante poli(etileno-butileno)-bloco-poliestireno (produto comercial) ou poli(etileno-butileno)-bloco-poliestireno sulfonado (produto sintetizado), respectivamente, na proporção de 0 a 6 %. O agente compatibilizante poli(etilenobutileno)- bloco-poliestireno sulfonado foi preparado neste Trabalho a partir do poli(etileno-butileno)-bloco-poliestireno. Todas as misturas preparadas foram caracterizadas quanto às suas propriedades mecânicas através de ensaios de impacto e de tração. As superfícies de fratura criogênica das misturas foram observadas através de microscopia eletrônica de varrredura para caracterização da sua textura. As blendas apresentaram valores de módulo de Young intermediários àqueles observados para o PET (3,54 GPa) e PEBD (110 MPa), entre 1,32 GPa e 2,84 GPa. O mesmo foi observado para a resistência à tração na ruptura, cujos valores das blendas variaram de 13,3 MPa a 33,9 MPa, comparados com 59,6 MPa e e 0,49 MPa para PET e PEBD, respectivamente.In these work blends of poly(ethylene tereftalate) (PET) and low density polyethylene (LDPE) were prepared and studied. The PET/PEBD blend presents scientific and technological interests due to the possibility of combining the high thermal stability and high elasticity modulus of PET with the fracture resistance and low temperature flexibility of LDPE. Two series of PET:LDPE blends with different relative proportions were prepared by melting mixture in a twin-screw extruder having as compatibilizing agent poly(ethylene-butylene)-block-polystyrene (commercial product) or sulfonated poly(ethylene-butylene)-block-polystyrene (synthesized product), respectively, in the range 0-6 %. The compatibilizing agent sulfonated poly(ethylene-butylene)-blockpolystyrene was prepared in this work from poly(ethylene-butylene)-blockpolystyrene. The mechanical properties of the blends were characterized by impact resistance tests and extensional tension tests. Textural analysis of blends was performed by observing their cryogenically fractured surfaces were characterized by scanning electron microscopy. The blends presented Young modulus values between those observed for PET (3.54 GPa) and LDPE (110 MPa), in the range from 1.32 GPa to 2.84 GPa. The same behavior was observed for the tensile strength, which values varied from 13.3 MPa to 33.9 MPa, compared to 59.6 MPa and 0.49 MPa for PET and LDPE, respectively.
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Melo, Juraj. « Aplikace pro tvorbu sad testů GUI ». Master's thesis, Vysoké učení technické v Brně. Fakulta informačních technologií, 2013. http://www.nusl.cz/ntk/nusl-236402.
Texte intégralRésumé :
This thesis describes a system for automated GUI testing using assistive technologies for accessing and manipulating GUI elements. The only input from the user to automated test system is a description of UI events and activities. For this purpose, a specialized language is proposed. The test system then automatically generates possible sequences of UI events applying a given criterion. Generated test set is executed by Python interpreter exploiting the Linux Desktop Testing Project (LDTP). Test system described in this thesis then provides reports and coverage evaluation for particular test cases and the whole test set.
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Daminelli, Elaine Nunes. « Uso de carmustina associada a nanoemulsões ricas em colesterol (LDE) para tratamento da aterosclerose induzida em coelhos ». Universidade de São Paulo, 2015. http://www.teses.usp.br/teses/disponiveis/5/5131/tde-11052015-161325/.
Texte intégralRésumé :
A aterosclerose é uma doença inflamatória crônica e proliferativa que tem início quando fatores de risco alteram o endotélio vascular. As partículas da nanoemulsão lipídica LDE concentram-se em sítios inflamatórios e de intensa proliferação celular, como acontece nas lesões ateroscleróticas. A carmustina, um fármaco antiproliferativo usado na quimioterapia do câncer, não foi ainda explorada no tratamento da aterosclerose. Em trabalhos anteriores, mostrou-se que a associação com a LDE reduz drasticamente a toxicidade da carmustina, o que já foi demonstrado em pacientes com câncer avançado. O propósito do estudo é avaliar se a carmustina associada à LDE pode promover o efeito antiproliferativo nas lesões ateroscleróticas induzidas em coelhos. No presente trabalho, dezoito coelhos machos da raça New Zealand, receberam dieta rica em colesterol a 1% durante 8 semanas. Depois de 4 semanas foram divididos em dois grupos: grupo controle, que recebeu injeção endovenosa contendo apenas solução salina e grupo tratado, que recebeu LDE-carmustina na dose de 4mg/Kg semanalmente durante 4 semanas. Foram avaliados perfil hematológico, lipídico, bioquímico, ponderal e o consumo de ração. Após a eutanásia, foram medidas as lesões ateroscleróticas macroscópicas. Em seguida, o arco aórtico foi analisado por morfometria e por imunohistoquímica. Observou-se que não houve diferença no perfil ponderal e no consumo de ração entre os grupos de estudo. Não houve toxicidade hematológica, hepática e renal no grupo tratado. No perfil lipídico, ao final do estudo, as concentrações de colesterol total, não HDL-C e triglicerídeos aumentaram em todos os grupos. Portanto, o tratamento com LDE-carmustina inibiu as lesões ateroscleróticas em aproximadamente 90%, comparado ao grupo controle. LDE-carmustina também reduziu a presença de macrófagos, de células de músculo liso e das células reguladoras de linfócitos T na íntima arterial, bem como a expressão protéica de MMP9, das citocinas inflamatórias e dos receptores de lipoproteínas. O tratamento da aterosclerose induzida em coelho com LDE-carmustina resultou em marcante redução das lesões na aorta, da proliferação e invasão da íntima por macrófagos e células musculares lisas, características da doença, além dos fatores inflamatórios. Tendo em vista que, associada à LDE, a carmustina tem baixa toxicidade, a nova preparação LDE-carmustina tem grande potencial para a terapêutica das doenças cardiovasculares de natureza ateroscleróticaAtherosclerosis is a chronic inflammatory and proliferative disease that starts when risk factors alter vascular endothelium. The particles of the lipid nanoemulsion LDE concentrate on inflammatory sites and with intense cell proliferation, as occurs in atherosclerotic lesions. The carmustine, an antiproliferative drug used in cancer chemotherapy has not yet been explored for the treatment of atherosclerosis. In previous work, we showed that the association with LDE drastically reduces toxicity of carmustine, which has been demonstrated in patients with advanced cancer. The purpose of this study is to evaluate whether carmustine associated with LDE can promote antiproliferative effect on atherosclerotic lesions induced in rabbits. In this study, eighteen male New Zealand rabbits were given a diet rich in cholesterol 1% for 8 weeks. After 4 weeks they were divided into two groups: control group, which received an intravenous injection containing only saline and treated group receiving LDE-carmustine dose of 4 mg/kg weekly for 4 weeks. Hematology, lipid, biochemical, weight profile and feed intake were evaluated. After euthanasia, macroscopic atherosclerotic lesions were measured. Then, the aortic arch was analyzed by morphology and by immunohistochemistry. It was observed that there was no difference in weight and profile in feed intake between the study groups. There were not hematological, hepatic and renal toxicity in the treated group. Lipid profile at the end of the study, the concentrations of total cholesterol, non-HDL-C and triglycerides increased in all groups. Therefore, treatment with LDE-carmustine inhibit atherosclerotic lesions in approximately 90%, compared to the control group. LDE-carmustine also reduced the presence of macrophages, smooth muscle cells and regulatory T cells in the arterial intima as well as the protein expression of MMP9, inflammatory cytokines and lipoprotein receptors. Treatment of rabbits with induced atherosclerosis LDE-carmustine resulted in marked reduction of lesions in the aorta, proliferation and invasion by macrophages and intimal smooth muscle cells, disease characteristics, in addition to inflammatory factors. Given that, associated with LDE, carmustine has low toxicity, the new formulation LDE-carmustine has great potential for the therapy of atherosclerotic cardiovascular disease nature