• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 339
  • 162
  • 62
  • 43
  • 15
  • 15
  • 14
  • 8
  • 8
  • 5
  • 4
  • 3
  • 2
  • 2
  • 1
  • Tagged with
  • 811
  • 88
  • 87
  • 83
  • 80
  • 79
  • 72
  • 69
  • 63
  • 56
  • 56
  • 55
  • 44
  • 42
  • 41
  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
591

Analyse der Surfaktantprotein A-Gene bei Patienten mit Verdacht auf einen Surfaktantproteindefekt

Scholz, Dietmar 18 June 2001 (has links)
Zusammenfassung Viele Untersuchungen deuten darauf hin, dass das Surfaktantprotein A (SP-A) sowohl an der Regulation des Surfaktanthaushalts als auch als unspezifisches Opsonin an der Abwehr von Pathogenen in der Lunge beteiligt ist. Zahlreiche Polymorphismen kennzeichnen die Gene der Proteinuntereinheiten SP-A1 und 2. Die häufigste Aminosäuresubstitution Val50Leu befindet sich in der kollagenartigen Domäne, die an den Kollektinrezeptor der Phagozyten bindet. Weitere existieren in der an der Bindung an Lipopolysaccharide, Surfaktantbestandteile und Rezeptoren auf Pneumozyten beteiligten Kohlehydraterkennungsregion (CRD) der globulären Domäne. Träger des schwach exprimierten Wildtypallels 1a0 des SP-A2-Gens haben ein erhöhtes Risiko, am Atemnotsyndrom des Neugeborenen (RDS) zu erkranken. Bei der Alveolarproteinose akkumulieren die hydrophilen Surfaktantproteine A und D in den Alveolen. In der vorliegenden Arbeit wurde eine nested PCR zur isolierten Amplifikation beider SP-A-Gene etabliert. 31 Patienten mit Verdacht auf einen Surfaktantproteindefekt wurden auf neue Restriktionsfragmentlängenpolymorphismen (RFLP) im SP-A1-Gen untersucht. Der in einer Familie konstante NcoI-Polymorphismus 1162C>T in Codon 39 und der NdeI-Polymorphismus 3138T>C in Codon 184 wurden mit einer Allelfrequenz von etwa 11 % detektiert. Die Sequenzen der entsprechenden Allele wurden kloniert. Bei 14 Patienten mit idiopathischer Alveolarproteinose, therapierefraktärem Surfaktantmangel oder rezidivierender Pneumonie wurden die SP-A-Gene sequenziert. Der bisher nur SP-A1 zugeschriebene Aminosäureaustausch Val50Leu wurde als Substitution 1220G>C bei zwei Patienten im SP-A2-Gen nachgewiesen. Drei Patienten mit Alveolarproteinose waren homozygot für die Substitution Gln223Lys in der CRD des SP-A2. Bei einem Patienten handelte es sich möglicherweise um eine somatische Mutation der Leukozyten-DNA im Rahmen einer Leukämie mit sekundärer Alveolarproteinose. Ein anderer war heterozygoter Träger des seltenen Allels 6a4 mit der Aminosäuresubstitution Arg219Trp in der CRD des SP-A1 und hatte die Alveolarproteinose erst im Erwachsenenalter entwickelt. Der dritte war homozygoter Träger des sehr seltenen Allels 1a3 des SP-A2 und verstarb im Alter von 6 Wochen an konnataler Alveolarproteinose (CAP), ohne dass ein bekannter Defekt des SP-B- oder des GM-CSF-Rezeptorgens vorlag. Die SSCP-Analyse konnte allelische Varianten als Einzelstrangkonformationspolymorphismen unterscheiden, war jedoch als Suchtest in heterozygoten Proben zu unspezifisch. Der hohe Gehalt an Polymorphismusinformation (PIC) macht den SP-A-Genort sftp1 zu einem nützlichen Marker bei der Untersuchung der Surfaktantproteine und anderer auf Chromosom 10 lokalisierter Gene. / Abstract Many studies give evidence of the role of surfactant protein A (SP-A) in the regulation of surfactant homeostasis and the defence from pathogens in the lung by opsonisation. The genes for the two protein subunits SP-A1 and SP-A2 are characterised by numerous polymorphisms. The most frequently substituted amino acid Val50Leu is located within the collagen-like region, which is recognised by the collectin-receptor on phagocytes. Further amino acids are substituted in the globular region, which is involved into the binding to lipopolysaccharides, surfactant particles, and receptors on pneumocytes by its carbohydrate recognition domain (CRD). Individuals carrying the weakly expressed wild-type allele 1a0 of SP-A2 have an increased risk of developing the respiratory distress syndrome (RDS) of the new-born. Alveolar proteinosis is a disease with accumulation of the hydrophilic surfactant proteins SP-A and SP-D in the alveoli. In this study a nested PCR for separate amplification of the two SP-A genes has been established. 31 patients with suspected deficiency of a surfactant protein has been investigated for new restriction fragment length polymorphisms (RFLP) in the SP-A1 gene. The NcoI-polymorphism 1162C>T in codon 39, which was constantly inherited in one family, and the NdeI-polymorphism 3138T>C in codon 184 have been detected with an allele frequency of around 11 %. The DNA sequences of these alleles have been cloned. In 14 patients suffering from idiopathic alveolar proteinosis, therapy-refractory surfactant deficiency, or recurrent pneumonia the SP-A genes have been sequenced. The substituted amino acid Val50Leu, which was previously considered exclusively in SP-A1, has been detected in SP-A2 in two patients. Three patients with alveolar proteinosis proved to be homozygous for the substitution Gln223Lys within the CRD of SP-A2. One of these patients might have a somatic mutation in the DNA of his leucocytes, with alveolar proteinosis developing secondary to his leukaemia. Another one developed alveolar proteinosis as an adult and was heterozygous for the rare allele 6a4 which includes the substituted amino acid Arg219Trp in the CRD of SP-A1. The third one proved to be homozygous for the very rare allele 1a3 of SP-A2 and died at 6 weeks of age from congenital alveolar proteinosis (CAP) without having one of the known mutations responsible for this condition within the genes for surfactant protein B (SP-B) or the GM-CSF receptor protein. The allelic variants could be differentiated by single strand conformation polymorphism but the SSCP-analysis was not enough specific for the screening of heterozygous DNA. Due to its high polymorphism information content (PIC), the SP-A gene locus sftp1 is a useful genetic marker for the analysis of the surfactant proteins and other genes located on chromosome 10.
592

Estudo da interação de líquidos iônicos com proteínas modelo / Study on the interaction of ionic liquids with model proteins.

Raw, Juliana 25 October 2016 (has links)
Líquidos iônicos (LIs) são sais que se encontram no estado líquido em temperaturas menores que 100ºC e que vêm ganhando protagonismo na área chamada química verde, prometendo: substituir solventes nocivos ao meio ambiente, aprimorar componentes eletrônicos, favorecer biocatálises dentre outros. Sua alta estabilidade e baixa toxicidade são frequentemente afirmadas, porém, devem ainda ser melhor investigadas. Com o objetivo de implementar o entendimento da interação dos líquidos iônicos com sistemas de relevância biológica, realizamos um estudo sistemático acerca da interação de 3 diferentes líquidos iônicos anfifílicos de mesma cabeça polar e diferentes caudas carbônicas ([C10mim][Cl], [C12mim][Cl] e [C14mim][Cl]) com 3 diferentes proteínas modelo, através das técnicas de absorção óptica, fluorescência, dicroísmo circular (CD) e espalhamento de raios-X a baixos ângulos (SAXS). Para Tanto, utilizamos as proteínas BSA e HSA (Albuminas de Soro Bovino e Humano, respectivamente) além da lisozima. Observamos a supressão da fluorescência das proteínas em todos os casos analisados, onde a diminuição da intensidade correspondeu a, para as proteínas BSA, HSA e lisozima, respectivamente, (55±3)%, (16.1±0.8)% e (4.1±0.2)%, em presença de 0.6mM de [C14mim][Cl], (38±2)%, (13.2±0.7)% e (0.6±0.1)% em presença de 0.6mM de [C12mim][Cl] e (11.0±0.5)%, (9.2±0.5)% e (0.0±0.1)% em presença de 0.6mM de [C10mim][Cl]. Os espectros de absorbância e fluorescência de todos os sistemas nos indicam uma interação de contato entre as proteínas e os líquidos iônicos. Constatamos também o deslocamento do pico de fluorescência, das proteínas BSA e HSA, para menores comprimentos de onda (blue-shift), na medida em que a concentração de LI era aumentada. O máximo deslocamento () alcançado correspondeu a (21±1)nm para ambas albuminas, enquanto que a lisozima não apresentou deslocamento significativo. O blue-shift pode ser explicado pela aproximação das cadeias carbônicas e formações de pontes de hidrogênio nas proximidades dos triptofanos. De acordo com a técnica de SAXS, evidenciamos o aumento do raio de giro das proteínas, na medida em que adicionamos LIs. O raio de giro da BSA, da HSA e lisozima em ausência de LI são (29±1)Å, (30±1)Å e (15±1)Å, respectivamente, e passam para (46±1)Å, (44±1)Å e (20±1)Å respectivamente, em presença de 0.6mM de [C14mim][Cl]. As curvas de SAXS também apresentaram o indício da formação de estruturas micelares a partir de uma dada concentração. Além da alteração em sua estrutura terciária, os dados de CD indicam uma leve perda de estrutura secundária de ambas as albuminas (BSA e HSA), passando de 80 para 65% de -hélice em ausência e presença de 0.6mM de [C14mim][Cl], respectivamente. Sugerimos que as interações das proteínas com os líquidos iônicos, embora inicialmente movidas por forças eletroestática, possuem como principal fator o efeito hidrofóbico, portanto quanto maior a cadeia carbônica do LI maior é sua interação com a proteína. Tal interação causa o desenovelamento das proteínas e formação de um complexo e estruturas micelares a altas concentrações de LI. Acreditamos que este trabalho traz novas informações acerca da interação dos LIs com proteínas modelo, indicando sua capacidade de alterar a conformação das mesmas. / Ionic liquids (ILs) are salts that are liquid at temperatures smaller than 100 ° C and are gaining prominence in the so-called green chemistry, promising: replace harmful solvents to the environment, improve electronic components, and favor biocatalysis, among others. Its high stability and low toxicity are often asserted; nevertheless, they are ascribed to ILs due to its small volatility. With the aim of improving the understanding of the interaction of ILs with biological relevant systems, we conducted a systematic study of the interaction of three different ionic liquids of the same polar head and different paraffinic tails ([C10mim][Cl], [C12mim][Cl] and [C14mim][Cl]) with three different model proteins, through the techniques of optical absorption, fluorescence, circular dicrhoism (CD) and small angle X-ray scattering (SAXS). To do so, we use BSA and HSA proteins (Bovine Serum Albumin and the Human Serum Albumin, respectively) and lysozyme. We observed fluorescence quenching, of all studied proteins, where the decrease in the fluorescence was (for BSA, HAS and lysozyme, respectively): (55 ± 3)%, (16.1 ± 0.8)% to (4.1 ± 0.2 )% in the presence of 0.6mm [C14mim][Cl], (38 ± 2)%, (13.2 ± 0.7)% to (0.6 ± 0.1)% in the presence of 0.6mm [C12mim][Cl] and ( 11.0 ± 0.5)% (9.2 ± 0.5)% and (0.0 ± 0.1)% in the presence of 0.6mm [C10mim][Cl]. UV-vis absorbance spectra and fluorescence indicate all systems in a contact interaction between proteins and ionic liquids. We also note the shift of the fluorescent peak of BSA and HSA proteins for shorter wavelengths (blue-shift), as the IL content was increased. The maximum shift () achieved corresponded to (21 ± 1) nm for both albumins, whereas no significant displacement was observed for lysozyme. The blue-shift can be explained by the approach of carbon chains and formation of hydrogen bonds in the vicinity of tryptophan. SAXS data indicate an increasing in the proteins radius of gyration value as ILs was added in the solution. The turning radius of BSA, HSA and lysozyme in the absence of IL are (29 ± 1) Å, (30 ± 1) Å and (15 ± 1) Å, respectively, and go to (46 ± 1) Å, ( 44 ± 1) Å and (20 ± 1) Å, respectively, in the presence of 0.6mm [C14mim][Cl]. The SAXS curves also show evidence of the formation of micellar structures from a given concentration. Besides the change in its tertiary structure, the CD data indicates a slight loss of secondary structure of both albumins (BSA and HSA), from 80 to 65% of -helix in the absence and presence of 0.6mm [C14mim][Cl], respectively. We suggest that the interactions of the protein with the ionic liquid, although initially driven by electrostatic forces, have a major factor hydrophobic effect and thus the higher the carbon chain of greater IL is its interaction with the protein. This interaction causes unfolding of the protein and formation of a micellar structures at high concentrations of IL. We believe this work provides new information about the interaction of ILs with model proteins, indicating its ability to alter the conformation of the same.
593

Structure et stabilité des réseaux lamellaires gélifiés / Structure and stability of lamellar gel networks

Lagarde, Lauriane 30 November 2012 (has links)
Cette thèse apporte une nouvelle vision de la structure des réseaux lamellaires gélifiés. Les systèmes étudiés, choisis pour des applications cosmétiques, sont basés sur des mélanges d’alcools cétéaryliques, de tensioactifs esters de phosphate et d’eau. À l’aide de nombreuses méthodes analytiques, nous avons prouvé que la formation d’une structure lamellaire est possible à des forces ioniques allant jusqu’à 2.2 mol∙L-1. Pour la première fois, un comportement de percolation élastiqueest rapporté en fonction de la concentration en alcools gras et tensioactifs. Le seuil au-dessus duquel un réseau percolé apparaît est ici à 3 % et est indépendant de la force ionique et de la présence de longues chaînes d’oxyde de polyéthylène ancrées dans les bicouches. Au-dessus de 3 %, les systèmes passent de structures vésiculaires unilamellaires à des paquets plans de lamelles, qui forment un réseau tridimensionnel pouvant contenir d’importantes quantités de solution aqueuse. L’impact de la force ionique, de la présence d’oxyde de polyéthylène et de la nature des contre-ions sur lespropriétés rhéologiques et sur la stabilité de la formulation est ensuite étudié. Une augmentation inhabituelle du module élastique et de l’énergie de cohésion est observée lorsque la force ionique est accrue. L’addition d’oxyde de polyéthylène, à l’inverse, diminue d’un ordre de magnitude les valeurs du module élastique du réseau. Les systèmes étudiés sont stables à l'échelle macroscopique et on peut distinguer dans le gel, selon sa mobilité : l’eau fixée entre lamelles, l’eau restreinte en troisdimensions et l’eau libre, extractible par ultracentrifugation. / This Ph.D. brings new insights into the structure of lamellar gel networks. The systems studied are relevant for cosmetic applications and based on a mixture of cetearyl alcohols, phosphates esters surfactants and water. Using several analytical methods, we show that the formation of a lamellar gel structure is possible up to the ionic strength of 2.2 mol∙L-1. For the first time for such systems, an elastic percolation behavior as a function of the concentration of fatty alcohols and surfactants isreported. The threshold above which a percolated network is formed is found here at 3 % and appears to be independent of the ionic strength and of the presence of long polyethylene oxide chains between the bilayers. Above 3 %, the systems transform from unilamellar vesicle-like structures towards planar stacks of lamellae, connected together in a three dimensional network,that can hold large amounts of aqueous solution. The impact of the ionic strength, of polyethylene oxide chains and of the nature of the counterions on the rheological properties and on the stability of the formulation is then investigated. When the ionic strength is raised, an unusual increase of the elastic modulus and of the cohesive energy of the network is observed. At the opposite, the addition of polyethylene oxide chains decreases of one order of magnitude the values of the elastic modulus,leading to much softer networks. All systems studied are macroscopically stable and one finds in the gel, according to water mobility: interlamellar fixed water, water restricted in three dimensions and free water, drainable by ultracentrifugation.
594

Caracterização estrutural de sistemas biológicos de diferentes classes: um estudo pela técnica de SAXS / Structural characterization of biological systems from different classes: A study by the SAXS technique

Oseliero Filho, Pedro Leonidas 28 November 2018 (has links)
Esta tese apresenta resultados da caracterização estrutural de três sistemas de classes diferentes por meio, principalmente, da modelagem de dados de espalhamento de raios X a baixos ângulos (SAXS). No sistema surfactante-surfactante as micelas mistas são formadas por dodecil sulfato de sódio (SDS) e um dos surfactantes da série Tween (Tween 20, 40, 60 e 80). A modelagem adotada impôs vínculos moleculares uma vez que os dados de SAXS estavam em escala absoluta. Isso reduziu a ambiguidade nos valores dos parâmetros ajustáveis e permitiu verificar que os dados de SAXS são satisfatoriamente descritos considerando-se que as micelas são elipsoides de revolução core-shell, podendo ser prolatas ou oblatas dependendo do tipo de Tween empregado. Para o sistema proteína-surfactante, a metodologia experimental utilizada permitiu um estudo estrutural e termodinâmico dos complexos formados por meio do acompanhamento do processo de ligação de SDS às proteínas lisozima e alfa-lactalbumina. A técnica de calorimetria de titulação isotérmica (ITC) forneceu um panorama geral sobre a desnaturação proteica e norteou os experimentos seguintes de SAXS e dicroísmo circular (CD). Por meio da análise dos dados de CD concluiu-se que as proteínas perdem quase totalmente sua estrutura terciária, mas não a secundária (esse estado é conhecido como molten globule). Já a modelagem de SAXS em escala absoluta com imposição de vínculos permitiu concluir que os complexos proteína-surfactante podem ser entendidos micelas decoradas, isto é, a proteína está distribuída sobre a superfície de uma micela de SDS. Esse modelo, aliado à abordagem experimental empregada, permitiu a caracterização sistemática dos complexos durante a desnaturação proteica. Em relação ao sistema lipossomas-(bio)ativos, a análise dos dados de SAXS por meio do Método da Deconvolução Gaussiana usando bicamadas simétricas, para os sistemas Phospholipon 90H curcumina/vitamina D3 e dipalmitoilfosfatidilcolina de soja (DPPC) ácido láurico (LA), e assimétricas, para o caso fosfatidilcolina de ovo (EPC) sumatriptano (SMT), permitiu acompanhar mudanças na estrutura das mesmas ocasionadas pela presença dos (bio)ativos. Verificou-se em todos os casos que a espessura da bicamada se mantém praticamente constante. A flexibilidade membranar aumenta, seja em função da temperatura, para o sistema Phospholipon 90H curcumina/ vitamina D3, seja em função da concentração de (bio)ativos, como nos outros dois casos. Para estes, concluiu-se pela análise dos perfis de contraste de densidade eletrônica que os (bio)ativos interagem preferencialmente com as cabeças polares dos fosfolipídeos que constituem os lipossomas, possivelmente causando defeitos topológicos nessa região e ocasionando o aumento da flexibilidade membranar mencionada antes. LA, diferentemente de SMT, induz uma transição de lipossomas multilamelares para unilamelares, e esse fenômeno é grandemente influenciado pelo pH do meio. / This thesis presents a structural characterization of three systems of different classes through, mainly, the small angle X-ray scattering (SAXS) technique. In the surfactant-surfactant system the mixed micelles are composed by sodium dodecyl sulfate (SDS) and one of the Tween surfactants (Tween 20, 40, 60 and 80). The adopted modeling imposed molecular constraints since the SAXS data was in absolute scale. This procedure reduced the ambiguity in the values of the adjustable parameters and allowed to verify that SAXS data is satisfactorily described considering that the micelles are core-shell revolution ellipsoids which can be prolate or oblate depending on the type of Tween used in the micelle. For the protein-surfactant system, the applied experimental methodology allowed a structural and thermodynamic study of the complexes formed through monitoring the binding of SDS to the proteins lysozyme and alpha-lactalbumin. Isothermal titration calorimetry (ITC) technique provided an overview of proteic denaturation and guided the following experiments of SAXS and circular dichroism (CD). From CD data analysis it was concluded that the proteins lose almost totally their tertiary structure, but not the secondary one (this state is known as \"molten globule\"). On the other hand, SAXS data modeling in absolute scale with molecular constraints leaded to the conclusion that protein-surfactant complexes can be considered decorated micelles in which the protein is distributed over a SDS micelle surface. This model, combined to the adopted experimental procedure, allowed the systematic characterization of the complexes along the protein denaturation. In the liposome-(bio)actives system, the SAXS data analysis using the Gaussian Deconvolution Method assuming symmetric bilayers, for the systems Phospholipon 90H curcumin /vitamin D3 and soybean dipalmitoyl phosphatidylcholine (DPPC) lauric acid (LA), and asymmetric bilayers, in the case of egg phosphatidylcholine (EPC) sumatriptan (SMT) system, allowed to follow changes in the lipid bilayer structure induced by the presence of the (bio)actives. It has been found, in all cases, that the bilayer thickness remains approximately. Membrane flexibility increases, depending on the temperature, for the Phospholipon 90H curcumin /vitamin D3 system, or as a function of the (bio)actives concentrations, as in the other two cases. For those, it was concluded, by the analysis of electron density contrast profiles, that the (bio)actives preferentially interact with the polar heads of the phospholipids forming the liposomes, possibly causing topological defects in that region and leading the membrane flexibility increase. LA, unlike SMT, induces a transition from multilamellar to unilamellar liposomes, and this phenomenon is greatly influenced by the pH of the medium.
595

Tomografia por coerência óptica (OCT), reologia, análise térmica e tamanho de partículas aplicados na caracterização de sistemas emulsionados de orientação de uso cosmético / Optical coherence tomography (OCT), rheology, thermal analysis and particle size determination applied for the characterization of cosmetic use emulsified systems

Prestes, Paula Souza 17 February 2012 (has links)
Os atributos físicos, físico-químicos e químicos dos sistemas emulsionados são influenciados pelas características das gotículas da fase interna destes, como: concentração, tamanho e morfologia. Dessa forma, os objetivos envolveram a caracterização física e físico-química de sistemas emulsionados obtidos a partir dos tensoativos álcool estearílico 21 OE (óxidos de etileno) (steareth-21) e álcool oleílico 20 OE (oleth-20), bem como, a introdução da tomografia por coerência óptica (OCT) como técnica analítica para determinação do tamanho de partículas e caracterização morfológica das emulsões. Prepararam-se três formulações, diferindo-se no tensoativo utilizado, sendo o sistema emulsionado SE-1 composto por 8,0% (p/p) de oleth-20; o SE-2 por 4,0% (p/p) de oleth-20 e 4,0% (p/p) steareth-21; e o SE-3 por 8,0% (p/p) steareth-21. Avaliaram-se a estabilidade preliminar, o valor de pH, os perfis reológico e termogravimétrico. A presença de fase gel cristalina foi determinada por meio da microscopia com luz polarizada e, o tamanho das gotículas, por meio da microscopia óptica comum, difração a laser e OCT. As amostras não apresentaram sinais de instabilidade por meio dos testes da centrifugação e do estresse térmico. O valor de pH foi considerado compatível com o da pele humana (4,6 a 5,8). Os sistemas apresentaram comportamento reológico não-Newtoniano pseudoplástico. SE-1 apresentou viscosidade aparente inferior (223,53 mPa.s) e área de histerese (2238,38 Pa/s) estatisticamente igual ao SE-2 (2911,19 Pa/s); SE-2 apresentou valor intermediário de viscosidade aparente (332,20 mPa.s) e, SE-3, valores superiores para ambos os parâmetros (636,40 mPa.s e 4248,97 Pa/s). Os testes oscilatórios constataram a predominância do caráter elástico para os três sistemas. Por meio da termogravimetria, o perfil das três amostras foi semelhante, independentemente do tipo e concentração do tensoativo não-iônico. Observou-se a presença de fase gel cristalina para os três sistemas, sendo aparentemente mais pronunciado para o SE-2. Tanto na análise microscópica quanto na difração a laser foram obtidos tamanho médio de partículas menor que 6,0 µm. De acordo com os resultados da OCT, as partículas menores que 6,0 µm não foram possíveis de serem conclusivamente observadas e aquelas maiores sugeriram ser a fase interna dos sistemas. / The physical, physicochemical and chemical attributes of the emulsified systems are influenced by the characteristics of their internal phase droplets, such as: concentration, size and morphology. Thus, the aims involved the physical and physicochemical characterization of emulsions obtained from the stearyl alcohol condensed with 21 mols ethylene oxide (EO) (steareth-21) and oleyl alcohol with 20 mols EO (oleth-20), as well as, the introduction of the optical coherence tomography (OCT) as the analytical technique tool to the determination of the particle size and morphological characterization of the emulsified systems. Three formulations were prepared, differing at the surfactant used, being the emulsified system SE-1 composed by 8.0% (p/p) of oleth-20, the SE-2 by 4.0% (p/p) of oleth-20 and 4.0% (p/p) steareth-21; and the SE-3 by 8.0% (p/p) steareth-21. The preliminary stability was evaluated, such as the ph value and the rheological and thermogravimetric profiles. The presence of the crystalline gel phase was determined from microscopy with polarized light and the droplet size through regular optical microscopy, laser diffraction and OCT. The samples did not present signs of instability throughout the centrifugation and thermal stress tests. The ph value was considered compatible to human skin (4.6 to 5.8). Systems represent the non-Newtonian pseudoplastic rheological behaviour. The SE-1 presented inferior apparent viscosity (223.53 mPa.s) and the hysteresis area (2238.38 Pa/s) statistically equal to SE-2 (2911.19 Pa/s); the SE-2 presented an average value of apparent viscosity (332.20 mPa.s) and, the SE-3, superior values to both parameters (636.40 mPa.s and 4248.97 Pa/s). The oscillating tests verified the elastic character predomination to the three systems. Throughout the thermogravimetry, the profile of the three samples was similar, independent from the kind and concentration of the non-ionic surfactant. The presence of the crystalline gel phase was identified at the three systems, being apparently more pronounced to the SE-2. Either at the microscopic analysis as well as at the laser diffraction were obtained an average size of the particles minor than 6.0 µm. According to OCT results, the particles below 6.0 µm were not possible to be identified and the major particles were suggested be the internal phase of the systems, however new studies should be performed.
596

Formulation de nouvelles mousses d'extinction d'incendie avec impact réduit sur environnement / Formulation of new fire-fighting foams with reduced impact on the environment

Arnault, Joris 11 December 2018 (has links)
Les mousses extinctrices sont utilisées sur les feux de catégorie B (solvants inflammables). L’efficacité des mousses actuelles contenant des agents moussants fluorés est apportée par la formation d’un film aqueux à la surface du carburant enflammé. Les entreprises recherchent et développent de nouveaux agents moussants sans fluor car ce type de tensioactif est nocif pour l’environnement et la santé. Des mousses très stables sont nécessaires pour qu'une couche épaisse de mousse résiste aux températures élevées et au démoussage par le solvant et évite ainsi la ré-inflammation.Dans ce travail, l’amélioration de la stabilité de la mousse a été réalisée en utilisant des épaississants dans une solution moussante avec des tensioactifs non fluorés. Des polysaccharides tels que la gomme xanthane ont été utilisés et ses interactions avec des tensioactifs ont été étudiés. Les complexes formés par ces interactions ont été utilisés dans le but d’améliorer la stabilité de la mousse et sa résistance aux flammes. Ceci engendre des mousses de plus faible moussabilité mais de plus grande stabilité. Des tests à échelle réduite ont été réalisés selon la norme EN1568 et ont montré l’efficacité de l’addition de gomme xanthane. Ces formulations innovantes associant des polysaccharides et des agents moussants sont de bonnes alternatives aux formules contenant des tensioactifs fluorés. Le mécanisme d’action des hydrotropes améliorant la moussabilité a aussi été étudié / Firefighting foams are used on class B fires (flammable solvents). The efficiency of currently used foams containing fluorinated foaming agents is ensured by the formation of an aqueous thin film on top of the burning solvent. The formation of such film requires the use of fluorinated surfactants that specifically adsorb at the water-air interface. Companies currently develop fluorine-free products for firefighting foams because this kind of surfactants is harmful for the environment and health. Very stable foams are necessary to the formation of a thick layer of foam that resists high temperatures and defoaming by the solvent, preventing fire re-ignition.In this work, improved foam stability was achieved by using thickeners in the foaming fluid together with the non-fluorinated surfactants. Polysaccharides such as xanthan gum were used and their interactions with surfactants were investigated. Complex species formed by such interactions were used in order to improve foam stability and resistance against flames. This causes a lower foamability but higher stability of foams. Small scale fires extinguishing experiments performed following the standard EN1568 showed the efficiency of xanthan gum addition. These innovative formulations combining polysaccharides and foaming agents are suitable alternatives to those containing fluorinated surfactants. The action mechanism of hydrotropes improving foamability has also been studied
597

The central regulation of blood pressure and salt appetite by brain 11β- hydroxysteroid dehydrogenase type 2 : a novel gene targeting technique

McNairn, Julie Anne January 2018 (has links)
Hypertension is the chronic elevation in blood pressure that is regulated in part through the retention and regulation of sodium retention and excretion in the kidneys. Hence the kidney has been considered the organ that regulates blood pressure. There are a cohort of patients that suffer with high blood pressure due to lack of 11β-hydroxysteroid dehydrogenase-type 2 (11β-HSD2) expression (which inactivates glucocorticoids (GCs), allowing selective activation of mineralocorticoid receptors (MR) by aldosterone) that results in hypertensive and increased salt appetite phenotypes - a condition known as syndrome of apparent mineralocorticoid excess (SAME). This disorder can be recapitulated in the mouse through the global deletion of 11β-HSD2, which results in over activation of the MR driving an elevation in blood pressure. However, the distinction between blood pressure elevation because of kidney dysfunction with loss of 11β-HSD2 or increased salt appetite due to loss of brain 11β-HSD2 expression is not clear from the global 11β-HSD2 knockout model. Salt appetite is regulated by regions of the brain out-with the blood-brain barrier, known as circumventricular organs. In the mouse, salt appetite is controlled by aldosterone-sensitive cells in the nucleus of the solitary tract (NTS) in the brain stem, where 11β-HSD2 is expressed to provide mineralocorticoid selectivity. However, in the fetal brain, 11β-HSD2 is widely expressed, protecting against adverse GC action that alters brain development and increases susceptibility to psychiatric disorders as adults. 11β-HSD2 deletion solely in the brain from embryonic day 12 resulting in GC fetal programming (HSD2BKO) causes effects on both behaviour and salt appetite. To determine the role of developmental versus adult expression of brain 11β- HSD2, mice with deletion of brain 11β-HSD2 from mid gestation (HSD2BKO) and mice with adult deletion of 11β-HSD2 in the NTS using lentivirus (HSD2.v- BKD) were compared. The phenotypes (salt appetite, blood pressure (BP), baroreceptor response (BRR) and cognition), can be categorised as either due to GC fetal programming (as indicated by HSD2BKO groups), or increased activation of MR in adult 11β-HSD2 expressing neurons (recapitulated in the HSD2.v-Cre groups). Salt appetite increased in both HSD2BKO and HSD2.v-BKD cohorts (mean percentage increase 65% n=8 and 46% n=6, compared to their respective controls), leading to an increased BP in both groups (+12% and +8%, respectively) as well as an impaired BRR, indicating all phenotypes are mediated by adult NTS neurons. However, spatial recognition memory (Object-in-Place task) is abolished in HSD2BKO mice, whereas, HSD2.v-BKD mice still retain short-term memory. Our data suggest that neural 11β-HSD2 protects against inappropriate activation of MR by corticosterone to regulate salt appetite and salt-induced rises in blood pressure. However, spatial recognition memory is not influenced by deletion of 11β-HSD2 in the adult brain, confirmation that this phenotype is underpinned by developmental programming by GCs, which is observed in the 11β-HSD2 brain KO. Salt appetite has been shown to be centrally regulated through the adult deletion of 11β-HSD2. From this, our data suggest that an increased salt appetite is due to adult loss of function of 11β-HSD2 rather than GC programming during development. Highlighting the NTS as a region for drug delivery to try and control salt appetite in salt sensitive individuals who struggle with administering a recommended change in diet. To develop this further, minimally invasive modes of delivery of viruses and drugs into the brain were investigated. In so doing, a non-invasive and reversible method to temporarily disrupt the blood brain barrier (BBB) was optimised. The technique required acoustic insonation of ultrasonic contrast agents (CAs) (gas microbubbles) adjacent to the BBB. These microbubbles (SonoVueTM, Bracco) were delivered via tail vein injection into the vasculature. To target the BBB, an ultrasonic transducer was suspended and focused through coupling gel onto the area of interest in the brain with skull the intact. The optimisation of this technique required determination of the focal position of the 3.5MHz transducer that was utilised, in addition to optimisation of the pulse length, pulse repetition frequency and power output of the ultrasound beam to enable the BBB to be disrupted. In addition, measurement of the attenuation of the ultrasound beam through ex vivo mouse skulls were measured. These results showed a 50% reduction in pressure amplitude from the baseline of 335.2mV (Baseline mean = 100% +/-SEM 0 n=3 (No skull), five regions across the skull averaged 47.79% +/-SEM 1.913 n=25 (using 5 different animals). In in vivo mice, after co-injection of the microbubbles with Evans Blue and insonation of the brain, disruption of the BBB was confirmed by the presence of Evans Blue dye in the brain, with no measurable damage occurring in the brain. This was confirmed by cell and nuclear morphology with no red blood cell extravasation into the surrounding tissue. The parameters used to open the BBB used a peak negative pressure of 2.1MPa (single pulse), transducer frequency 3.5MHz, 35,000 cycles over a 10ms burst at a pulse repetition frequency of 10Hz. The technique when applied in vivo in recovery animals is speculated to work by the focused ultrasound causing the microbubbles to oscillate within the vasculature adjacent to the BBB, resulting in high-shear stresses being generated on the tight junctions within the BBB. The resultant gaps in the BBB allow free circulating compounds (e.g. large dye molecules (Evans Blue - 960.8g/mol molecular weight) and adeno-associated-viruses (25nm with a packing capacity of 4.5kb) within the blood to pass into the brain, but there is no penetration of red blood cells (7μm). Longitudinal mouse experiments demonstrated that within 12-hours these gaps close with no long-term damage observed. Currently, utilising this technique, successful passage of an adeno-associated virus expressing GFP (as a marker) has been shown to pass into the brain (n=6 for each cohort including control) - indicating that the virus requires the ultrasound and microbubbles to facilitate its movement into the brain. Further technique optimisation is being explored looking at the role of CAs used in the opening and disruption of the BBB, comparing composition and size of the CAs. Microbubbles (2-3μm) and nanobubbles (200nm) were compared as well as lipid and non-ionic surfactant surface compositions, using volume of drug delivery and degree of disruption as outputs. Using this technique, the hydrophilic drug mimic calcein was delivered into the brain (n=5 non-ionic surfactant nanobubble, n=5 lipid nanobubble). Results have indicated that the delivery of calcein is most efficient when using non-ionic surfactant nanobubbles as opposed to lipid nanobubbles - with a greater volume of the drug being delivered into the cerebral tissue. Furthermore, the concentration and surface composition of the nanobubble have an effect as to the size and potential damage to the brain when opening the BBB. In conclusion, it has been shown that it is possible to non-invasively open the BBB and deliver viruses and dye into the brain. In addition, this thesis has investigated the use of nanobubbles as both facilitators to opening the BBB and delivery vectors for potentially therapeutic drugs. Finally, a non-invasive opening of the BBB has been achieved using focused ultrasound. Ultimately this non-invasive opening of the BBB can be used to achieve delivery of larger molecules (such as antibodies and viruses) into the brain to target treatments. Focused ultrasound brain targeting can be applied to the potential treatment of salt appetite regulation in the NTS. For the individuals who suffer from salt sensitive hypertension, the NTS can be targeted to reduce the drive to ingest high salt diets. Furthermore, the continuation of research into the central control of BP, salt appetite and baroreceptor reflex control can become better understood, using less invasive delivery techniques to the brain.
598

Influência da adição de tensoativos nas propriedades dos hipocloritos de sódio e cálcio / Influence of surfactants addition on the properties of sodium and calcium hypochlorite

Iglesias, Julia Eick January 2016 (has links)
O objetivo do presente estudo foi o de avaliar a influência da associação dos tensoativos cetrimida 0,2%, cetrimida 0,1% e cloreto de benzalcônio 0,008% aos hipocloritos de sódio e de cálcio 2,5% nas propriedades de pH, quantidade de cloro livre, tensão superficial, ângulo de contato, dissolução pulpar e atividade antimicrobiana. O pH e a concentração de cloro ativo foram avaliados por pHmetro digital e pela titulação, respectivamente. A tensão superficial foi mensurada através da técnica do anel de platina com um tensiômetro de Du Noüy. O ângulo de contato das soluções em bases de dentina humana foi aferido pelo software Drop Shape Analyzer. Para a análise da dissolução pulpar foram utilizados fragmentos de polpas bovinas e os resultados foram expressos por percentual de perda de massa. A atividade antimicrobiana frente ao Enterococcus faecalis foi realizada pelo método de difusão em Ágar. Os resultados mostraram que a associação de tensoativos aos hipocloritos de sódio e cálcio não alterou as propriedades de pH, cloro livre e dissolução pulpar das soluções. O hipoclorito de cálcio apresentou o maior valor de tensão superficial (72,13 ± 1,82 mN/m). Quando associados aos tensoativos, os hipocloritos de sódio e cálcio tiveram uma redução significativa da tensão superficial. O mesmo foi observado para o ângulo de contato. Os tensoativos apresentam atividade antimicrobiana. A associação dos hipocloritos à cetrimida 0,2% ou 0,1% aumentou o halo de inibição frente ao Enterococcus faecalis. Concluiu-se que a associação de tensoativos não modificaram as propriedades de pH, cloro livre e dissolução pulpar dos hipocloritos de sódio e cálcio 2,5%. Porém, ela foi capaz de diminuir a tensão superficial e o ângulo de contato das soluções. Ainda, a associação da cetrimida 0,2% e 0,1% melhorou a capacidade antimicrobiana dos hipocloritos. / The aim of this study was to evaluate the influence of surfactants 0,2% or 0,1% cetrimide or 0,008% benzalkonium chloride on 2.5% sodium and calcium hypochlorite in the properties of pH, free chlorine content, surface tension, contact angle, pulp dissolution and antimicrobial activity. The pH and free chlorine content were evaluated by digital pHmeter and by titration, respectively. Surface tension was measured by the platinum ring technique with a Du Noüy tensiometer. Solution’s contact angle in human dentin surfaces was checked by Drop Shape Analyzer software. Bovine pulps were used for pulp dissolution analysis and the dissolving capacity was expressed by percentual weight loss. Antimicrobial activity over Enterococcus faecalis was evaluated through the ágar diffusion method. The surfactants association on sodium and calcium hypochlorites did not alter pH, free chlorine content and pulp dissolution properties. Calcium hypochlorite had the higher surface tension (72,13 ± 1,82 mN/m). However, when sodium and calcium hypochlorite were associated to surfactants, a significant reduction of surface tension occured. The same was observed for contact angle analysis. The surfactants used in this study have antimicrobial activity. The association of 0,2% or 0,1% cetrimide enhanced antimicrobial activity of both hypochlorites. It was possible to conclude that surfactants association did not alter pH, free chlorine content and pulp dissolution properties of 2,5% sodium and calcium hypochlorite. It was capable to reduce surface tension and contact angle of the solutions. Moreover, the 0,2% or 0,1% cetrimide association increased antimicrobial activity of hypochlorite.
599

Aplicação de proteases alcalinas das vísceras do tambaqui (Colossoma macropomum) e da carpa (Cyprinus carpio) como aditivo de detergentes em pó

ESPÓSITO, Talita da Silva 06 February 2006 (has links)
Submitted by (edna.saturno@ufrpe.br) on 2017-02-22T13:18:21Z No. of bitstreams: 1 Talita da Silva Esposito.pdf: 1198598 bytes, checksum: 814b0f7dce6420e7e8723706bb578b48 (MD5) / Made available in DSpace on 2017-02-22T13:18:21Z (GMT). No. of bitstreams: 1 Talita da Silva Esposito.pdf: 1198598 bytes, checksum: 814b0f7dce6420e7e8723706bb578b48 (MD5) Previous issue date: 2006-02-06 / Alkaline proteases are commercially important group of enzymes and have a large variety of applications, mainly in the detergent and food industries. The proteases currently uses in the market are serine proteases produced by Bacillus strains, principally. Fish viscera have wide biotechnological potential as a source of digestive proteases. Biotechnology provides a means for transforming such materials usually discarded into valuable produts such as enzymes. The objective of this research was to test if alkaline proteases from fish viscera could be used as an additive in commercially available detergent formulations. Viscera from Colossoma macropomum, the most important native fish for Brazilian aquaculture, and Cyprinus carpio, the second exotic fish in importance for Brazilian aquaculture, were extracted and used as a source of enzyme for this research. The crude extract obtained upon the homogenization of the viscera was submitted to a partial purification with ethanol. The protein content,proteolytic activity of the fractions thus obtained was assessed. The fraction presenting the highest proteolytic activity was further studied (30-70% of ethanol) resulting in 74.9% and 142.4% of protein recovery for tambaqui and carpa, respectively. This fraction was assayed at different temperatures and pH aiming to estimate the conditions for higher proteolysis. Temperarture and pH stability experiments were also carried out. Different commercial lyavailable detergents, surfactants and hydrogen peroxide were used to test the compatibility of these proteases with detergent formulations. The results reveal that these alkaline proteases extracted from C. macropomum show desirable characteristics for its use in laundry industry such as: retention of 73% and 63% of its initial activity in the presence of Surf® and 5% H202, respectively, after 1 hour of incubation at 40ºC. In addition to that it was observed a slight increase of the proteolytic activity in the presence of non-ionic (Tween 20 and Tween 80) and ionic surfactants (Saponin and Sodium cholate). On the other hand, the proteases extracted from the intestine of C. carpio were compatible with the surfactants and oxidants tested butdid not present the same property in the presence of commercially available detergents. / As proteases alcalinas são as enzimas de maior importância comercial devido a sua vasta aplicabilidade, sendo empregadas principalmente nas indústrias de detergentes e de alimentos. Atualmente, a maior parte das proteases utilizadas no mercado é produzida por bactérias do gênero Bacillus, no entanto, elas podem ser amplamente encontradas em um dos principais resíduos da indústria pesqueira, as vísceras. Portanto, uma forma de otimizar o aproveitamento do pescado e, conseqüentemente, reduzir o desperdício é reaproveitar esses subprodutos. Neste trabalho testou-se a aplicabilidade das proteases de vísceras de peixes como aditivo de detergentes em pó comerciais. Para extração das enzimas foram utilizadas vísceras de Colossoma macropomum e de Cyprinus carpio, principal peixe nativo e segundo peixe exótico da aqüicultura continental nacional, respectivamente. A partir deste material obteve-se o extrato bruto, que passou por uma semi-purificação fracional com etanol. As frações obtidas deste procedimento tiveram sua atividade enzimática e quantidade de proteínas determinadas para escolha da fração a ser trabalhada. A fração saturada com 30- 70% de etanol apresentou maior atividade específica tanto no tambaqui quanto na carpa, com rendimentos de 74,9% e 142,4%, respectivamente. Nesta fração verificou-se em que temperatura e pH as proteases apresentavam maior atividade, além da sua estabilidade em relação a esses parâmetros. Para testar a compatibilidade com detergentes comerciais, foram utilizados quatro detergentes comerciais, cinco agentes surfactantes e peróxido de hidrogênio em diferentes concentrações. Os resultados obtidos sugerem que as proteases alcalinas encontradas nas vísceras de tambaqui apresentam características ideais para utilização na indústria de detergentes em pó, como: retenção de até 73% da sua atividade na presença de Surf® e de 63% na presença de 5% de H2O2 após 1 hora de incubação a 40ºC. Além disso, a atividade da enzima foi estimulada na presença de surfactantes não-iônicos (Tween 20 e Tween 80) e iônicos (Saponin e Colato de sódio). As proteases obtidas a partir do intestino da carpa, no entanto, só foram estáveis na presença dos diferentes surfactantes e a 5% de H2O2, perdendo estabilidade quando adicionadas aos detergentes comerciais.
600

An?lise dos Processos de Flota??o e Oxida??o Avan?ada para o Tratamento de Efluente Modelo da Ind?stria do Petr?leo / Analysis of flotation and advanced oxidation processes for the treatment of a wastewater model of the petroleum industry

Silva, Syllos Santos da 22 February 2010 (has links)
Made available in DSpace on 2014-12-17T15:41:48Z (GMT). No. of bitstreams: 1 SyllosSS_DISSERT.pdf: 3274284 bytes, checksum: efc9ef709dfd1e06b4170ed41eedf3fb (MD5) Previous issue date: 2010-02-22 / The generation of wastes in most industrial process is inevitable. In the petroleum industry, one of the greatest problems for the environment is the huge amount of produced water generated in the oil fields. This wastewater is a complex mixture and present great amounts. These effluents can be hazardous to the environmental without adequate treatment. This research is focused in the analysis of the efficiencies of the flotation and photo-oxidation processes to remove and decompose the organic compounds present in the produced water. A series of surfactants derivated from the laurilic alcohol was utilized in the flotation to promote the separation. The experiments have been performed with a synthetic wastewater, carefully prepared with xylene. The experimental data obtained using flotation presented a first order kinetic, identified by the quality of the linear data fitting. The best conditions were found at 0.029 g.L-1 for the surfactant EO 7, 0.05 g.L-1 for EO 8, 0.07 g.L-1 for EO 9, 0.045 g.L-1 for EO 10 and 0.08 g.L-1 for EO 23 with the following estimated kinetic constants: 0.1765, 0.1325, 0.1210, 0.1531 and 0.1699 min-1, respectively. For the series studied, the most suitablesurfactant was the EO 7 due to the lower reagent consumption, higher separation rate constant and higher removal efficiency of xylene in the aqueous phase (98%). Similarly to the flotation, the photo-Fenton process shows to be efficient for degradation of xylene and promoting the mineralization of the organic charge around 90% and 100% in 90 min / A gera??o de res?duos na maioria dos processos industriais ? quase que inevit?vel. Na ind?stria do petr?leo, um dos grandes vil?es para o meio ambiente ? o enorme volume de ?guas produzidas nos campos de petr?leo. Este efluente apresenta composi??o complexa e aliado ao grande volume envolvido pode-se tornar bastante danoso ao meio ambiente quando descartado de forma inadequada. Esta pesquisa est? centrada na an?lise das efici?ncias dos processos de flota??o em coluna e oxida??o avan?ada por processo foto-Fenton para remo??o/degrada??o de org?nicos presentes na ?gua produzida. Uma s?rie de tensoativos derivados de ?lcool laur?lico foi utilizada na flota??o para promover a melhoria da cin?tica e efici?ncia de separa??o. Os experimentos foram realizados com efluente sint?tico contendo xileno como poluente modelo. Os dados experimentais obtidos da flota??o apresentaram cin?tica de 1? ordem, identificada pela qualidade dos ajustes lineares. As melhores condi??es encontradas foram 0,029 g.L-1 para o EO 7, 0,05 g.L-1 para o EO 8, 0,07 g.L-1 para o EO 9, 0,045 g.L-1 para o EO 10 e 0,08 g.L-1 para o EO 23 com as seguintes constantes de velocidade iguais a 0,1765, 0,1325, 0,1210, 0,1531, 0,1699 min-1, respectivamente. Para a s?rie estudada, o tensoativo mais adequado foi o EO 7 devido o menor consumo de reagente, maior constante cin?tica de separa??o e maior efici?ncia de remo??o do xileno da fase aquosa (98%). De forma similar a flota??o, o processo foto-Fenton demonstrou ser eficiente para degrada??o do xileno alcan?ando efici?ncia de mineraliza??o da carga org?nica entre 90% e 100% em 90 min

Page generated in 0.0818 seconds