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  • 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.
271

Avaliação de interações do ácido gálico frente a adjuvantes empregados em formas farmacêuticas sólidas / Evaluation of the interacion of gallic acid and pharmaceutical excipients employed in solid dosage forms

Longhini, Renata January 2006 (has links)
Neste trabalho foram avaliados o comportamento do ácido gálico e de adjuvantes tecnológicos frequentemente empregados em formas farmacêuticas sólida, e das suas misturas físicas, através de métodos termoanalíticos e por espectroscopia de infravermelho. Foi investigada também a influência da compactação sobre as misturas físicas equiponderais. Os adjuvantes avaliados foram amidoglicolato de sódio, celulose microcristalina, croscarmelose sódica, crospovidona, dióxido de silício coloidal, estearato de magnésio e polimetacrilato. O ácido gálico apresentou um comportamento térmico diferenciado nas misturas, assumindo, provavelmente, uma forma instável com menor ponto de fusão. Os resultados obtidos por DSC demonstraram interação de natureza física com mudança de entalpia para misturas do ácido gálico com celulose microcristalina, crospovidona, estearato de magnésio e polimetacrilato. A interação não pode ser confirmada por espectroscopia de infravermelho para a crospovidona e polimetacrilato, devido à sobreposição das bandas com o ácido gálico. Os demais adjuvantes também apresentaram interação física, porém, sem alteração da entalpia, confirmada por espectroscopia de infravermelho, relacionada ao estabelecimento de ligações de hidrogênio entre os componentes da mistura. A compactação demonstrou particular influência sobre a interação com celulose microcristalina, croscarmelose sódica e crospovidona. / In this work were evaluated the behavior of the gallic acid and technological excipients used in sold dosage forms and their physical powder mixtures, by Differential Scanning Calorimetry (DSC) and Thermogravimety (TGA) and infrared spectroscopy (IR). The influence of the compression force on the 1:1 (w/w) physical mixtures was also investigated. The excipients evaluated were sodium starch glycolate, microcrystalline cellulose, croscarmellose sodium, crospovidone, colloidal silicon dioxide, magnesium stearate and polymethacrylate. Gallic acid presented a different thermal behavior in the mixtures, assuming, probably, an unstable form with a lower melting point. The results obtained by (DSC) demonstrated the occurrence of physical interactions with enthalpy changes for the mixtures of gallic acid with microcrystalline cellulose, crospovidone, magnesium stearate and polymethacrylate. The interaction could not be confirmed by infrared spectroscopy for crospovidone and polymethacrylate, due to overlapping of the gallic acid IR bands. The other excipients also presented physical interaction, however, without alteration of the enthalpy, confirmed by IR, which could be correlated to the establishment of hydrogen bonds between the components of the mixture. The compression of the powder mixtures demonstrated a particular influence of the interaction of gallic acid with microcrystalline cellulose, croscarmellose sodium and crospovidone.
272

Comprehensive study of the heat resistance of dried Bacillus subtilis spores / Etude de la résistance à la chaleur des spores de Bacillus subtilis déshydratées

Hauck Tiburski, Julia 17 December 2013 (has links)
En réponse à un stress nutritif, les espèces du genre Bacillus sont susceptibles de former desspores métaboliquement dormantes résistantes à d’autres formes de stress. Ces spores peuventse retrouver à forte concentration dans beaucoup d’aliments secs, ce qui peut provoquer desintoxications alimentaires ou dégrader les aliments lorsqu’ils sont réhydratés. Comme leurdestruction est très difficile, la plupart des méthodes couramment utilisées pour décontaminerles aliments secs sont peu efficaces. L’objectif de ce travail est de comprendre l’influence del’hydratation de la spore sur l’inactivation des spores sèches de B. subtilis. Une étudefondamentale a été menée en soumettant les spores placées dans les capsules d’AnalyseEnthalpique Différentielle à différent traitements thermiques et en associant simultanémentles thermogrammes obtenus à la viabilité des spores traitées. Les résultats montrent lapersistance d’une teneur en eau relativement élevée dans le protoplaste des spores équilibréesà faible aw (0,13). De plus, une relation forte a été mise en évidence entre la teneur en eau duprotoplaste de la spore et sa sensibilité thermique. La spectroscopie IR à transformée deFourier a montré que cette sensibilité est fortement reliée à la dénaturation/agrégation desprotéines et à la libération de l’acide dipicolinique. Ces résultats ont finalement permis dedévelopper un procédé d’inactivation thermique sous pression (entre 2 et 7 bar) des sporessèches. Le maintien d’une pression d’azote dans le réacteur chauffé permet d’empêcherl’évaporation de l’eau du protoplaste des spores et donc de favoriser leur inactivation. A termeet après développement, ce procédé peut être un moyen original de décontaminationd’aliments secs. / In response to starvation, species from the genre Bacillus are able to form metabolicallydormant spores which are very resistant to multiple forms of stress. They are found in quitehigh concentrations in some dried foods which, upon rehydration, may lead to food deterioration or food-borne diseases. Moreover, their destruction is rather difficult and mostof the techniques commonly used to treat dry foods result in a very low spore inactivation.The aim of this work is to better understand the role spore hydration in the inactivation ofdried Bacillus subtilis spores. A fundamental study was conducted using DifferentialScanning Calorimetry pans as reactors to perform a heat treatment in dried spores andsimultaneously relate the thermograms to spore viability. Results show the persistence of arelatively high water concentration in the core of extremely dry spores. Besides, a strongrelation between this core water concentration and spore thermal sensitivity wasdemonstrated. This destruction was found to be highly related to proteindenaturation/aggregation and dipicolinic acid release through Fourier Transform InfraredSpectroscopy analysis. From this fundamental study, a procedure for the inactivation of driedspores using low pressures (2-7 bar) and high temperature was developed. The systemconsisted of a heated reactor in which gaseous nitrogen was compressed to prevent theevaporation of water from the spores and so favor spore inactivation (> 5 log10). This methodof inactivation could be an interesting new way to optimize the decontamination of driedfoods.
273

Théorie du développement territorial dans une économie de satiété / No title

Pirrone, Claudio 09 February 2012 (has links)
Partant du constat de la nature encore relativement ambiguë du concept de développement territorial, cette thèse en propose uneapproche à la fois plus rigoureuse et plus large que la simple identification de ce dernier avec le développement économique. Le chemind’analyse choisi s’articule en quatre phases, chacune traitée dans un chapitre différent.Tout d’abord, par le biais d’une brève analyse historique des relations entre la pensée politique, au sens de la gestion des affaires dela cité, et la pensée économique, ce travail met en lumière les raisons qui ont permis au fur et à mesure à la sphère économique de s’imposer,et de revêtir ainsi le rôle de finalité du développement quittant celui de simple instrument. Et, en effet, à certaines conditions, l’amalgamepeut être justifié, notamment en présence d’insuffisance des moyens de chacun pour assurer la couverture de ses propres besoins.Puisque le fait de faire reposer le développement des territoires sur l’aspect économique conduit implicitement à considérer commepérenne cette condition d’insuffisance, nous avons souhaité vérifier si les approches les plus courantes de la théorie économique étaient enmesure de prendre en compte les situations d’opulence. À cette fin, nous avons relâché l’hypothèse de non-satiété, qui est implicite tant dansla convexité des courbes d’indifférence en microéconomie que dans la « loi psychologique » de la Théorie Générale de Keynes.L’élargissement de la théorie économique à la condition de satiété, creusée sur le plan théorique et confrontée à la réalité au cours dela thèse, conduit à avoir un regard très éloigné des représentations habituelles des faits économiques. Et, une fois l’analyse élargie auxrelations entre territoires différents, on peut démontrer, à partir d’une perspective purement économique, la nature contradictoire des finalitéséconomiques du développement.Enfin, adoptant l’optique des territoires comme « construits sociaux », la thèse avance une proposition alternative, fondée sur leslibertés d’être et de faire et leur élargissement progressif, selon une logique voisine de l’approche par les capabilités d’A.Sen, sans pourautant s’y réduire. Cette démarche permet de mettre en cohérence l’économique et le non économique, dans une perspective qui intègrepleinement le concept de durabilité selon la proposition du Rapport Brundtland de 1987 et qui se cristallise dans un nouvel indicateursynthétique de développement, la « création d’espace de développement ». / As the concept of “territorial development” is still relatively ambiguous, this thesis proposes both a more rigorous and widerapproach than merely identifying it with the “economic development on a local area”. Our analysis goes through four distinct phases, each ofthem being dealt with in a different chapter.First, a brief historical analysis of relations between economic and political thoughts, in the sense of community affairsmanagement, emphasizes the reasons which allowed the economic sphere to progressively become more and more influential to the point toestablish itself as the finality of development and go over its status of a “tool”. Indeed, upon certain conditions, this shift can be justified,namely in presence of some scarcity of means in order to satisfy one’s own needs.Because making the concept of territorial development rely only on the economic aspect leads to implicitly consider the condition ofscarcity as permanent, we wished to verify if the current approaches to the economic theory were capable of taking into account the affluenceof developed countries. To this purpose, we relaxed the non-satiety hypothesis, which is implicit both in the convexity of the indifferencecurves in microeconomics and in the “psychological law” of Keynes’ General Theory.The extension of the economic theory to the condition of satiety, which was deeply looked into theoretically and checked against thereality all through the thesis, makes us gain a very unusual insight into economic phenomena. And, once the analysis was opened to therelations between different territories, we were able to demonstrate, from a purely economic point of view, the contradictory nature of theeconomic goals of development.Finally, taking territories as “social constructs”, the thesis suggests an alternative proposition, based on the freedoms to be and tomake, and their progressive enlargement, in a way close to Sen’s capability approach, yet not being a reduction of it. The proposed approachcouples coherently the economic and the non-economic spheres, in a development perspective which integrates completely the concept ofsustainability according to the proposition of the Brundtland Report, 1987, and it is summarized by a new synthetic development index, the“development space creation”.
274

Caracterización de microencapsulados aplicados sobre materiales textiles

Monllor Pérez, Pablo 06 May 2008 (has links)
La aplicación de microencapsulados a los textiles no es una aplicación que esté tan extendida como en otros campos, como puedan ser las industrias farmacéuticas, agroalimentarias y cosméticas. Los microencapsulados son una nueva forma de obtener acabados textiles que resultan de la aplicaciónsobre los tejidos de estos productos lo que proporciona "acabados no convencionales". La microencapsulación ha permitido la obtención de tejidos con fragancias y perfumes resistentes a los lavados. Los microencapsulados para aplicaciones textiles, a diferencia de las utilizadas en farmacia, no necesitan membranas solubles, salvo excepciones, ya que los principios activos de los núcleos de las microcápsulas, se liberan por rotura de la cápsula, o por permeabilidad de la misma; esto supone una diferencia importante con el resto de fabricaciones de microcápsulas, así como en las características de los polímeros a utilizar para las membranas, lo que nos proporciona un motivo de estudio. El uso continuado, de tejidos con microencapsulados conteniendo una materia activ cuyo efecto se manifiesta por rotura de algunas capsulas, evidentemente, genera una degradación y una pérdida del efecto transmitido y será todavía mayor, si se le suman los efectos de los mantenimientos. En este trabajo se ha determinado la degradación de las microcápsulas (sobre tejidos), en función del uso y el mantenimiento. Para ello se han preparado tejidos con concentraciones variables de un mismo producto (aroma microencapsulado) y sometido a diferentes ensayos. En la aplicación de los microencapsulados sobre los textiles, se han realizado ensayos, exclusivamente por impregnación, puesto que es el procedimiento que mejores resultados nos ha proporcionado. Como trabajo previo se han analizado las características de los productos microencapsulados comerciales, determinando el tamaño medio de las microcápsulas, la cantidad de materia activa por eliminación de agua, su comportamiento térmico mediante calorimetría di / Monllor Pérez, P. (2007). Caracterización de microencapsulados aplicados sobre materiales textiles [Tesis doctoral no publicada]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/1896 / Palancia
275

Fabrication of Lignin-Based Nanofibers: Influence of Lignin Type, Blend Ratios, and Total Polymer Concentration

Devadas, Suchitha - January 2020 (has links)
No description available.
276

Fyzikální stárnutí polypropylénu / Physical ageing of polypropylene

Weiss, Jiří January 2011 (has links)
Physical aging of commercially produced polypropylene homopolymers Mosten was studied. The work is focused on monitoring the changes in physical properties of polymer in the time period 90 days from the date of preparation of the test specimen. The aging of polymers was realized at storage temperatures of 23 and 80 °C. The changes in crystallinity, yield strength, modulus, elongation and impact strength using DSC method, tensile tests and impact tests according to Charpy were monitored. Molecular weight distribution was determined by means of GPC at each polymer. Relationships between the changes in physical properties and polymer molecular weight were sought.
277

Studium stability emulzí pomocí fyzikálně-chemických a optických metod / Study of emulsion stability by means of physical-chemical and optical methods

Kuchyňová, Jitka January 2011 (has links)
The diploma thesis deals with the stability determination of model O/W (30/70) emulsions at 25°C. In fact, the time and emulsifier concentration (Tego Care PS) dependences of physical properties (aging) were monitored. In the second part of the work, the influence of conservant on emulsion stabilities were studied. In order to study physical properties of emusions rheometry, differential scanning calorimetry (DSC) and optical microscopy were employed. The rheological measurement provided information on viscosity and viscoelastic modulus. DSC experiments used the repeated freezing/thawing cycles which allowed monitoring of changes in crystallization temperature of water present in emulsions and melting enthalpy of ice formed during the cooling. The optical microscopy was used to examine the change in oil droplet size in the course of emulsion destabilization and phase separation. In this case the image analysis was carried out using program HarFA. The results showed that due to the emulsion creaming, the oil droplets diffuse and aggregate which causes phase separation. Those processes were quickest for the emulsion with lowest emulsifier concentration 0.1 % (destabilization during 51 days) The emulsions with emulsifier concentration about 1.5 and 1.3 % were stable at least for 4 months. The presence of the coemulsifiers increased the elastic modulus and descreased the phase difference due to the network formation. It was shown that for the stability determination is necessary to use conservant due to risk of microbial contamination. DSC experiments allowed to distingush samples prepared under different conditions. Lower rotational speed during emulsion preparation caused the appearance of two melting and crystalization peaks while for higher speed only one peak was observed.
278

Unmixing of Phosphorus-bearing Melts on Earth and Mars

Busche, Tamara Miranda 26 March 2019 (has links)
No description available.
279

Physikalisch-chemische Charakterisierung von ausgewählten supramolekularen Kristalleinschlussverbindungen

Sumarna, Omay 23 September 2002 (has links)
Die vorliegende Arbeit befasst sich mit experimentellen Untersuchungen zur physikalisch-chemischen und strukturellen Charakterisierung von neuartigen supramolekularen Kristalleinschlussverbindungen am Beispiel der Clathrate der Wirtverbindung 2,2’-bis(9-hydroxy-9-fluorenyl)biphenyl mit Aceton (polar) sowie Chloroform (unpolar). Durch die Kombination von Röntgenstrukturanalysen mit systematischen Messungen thermodynamischer Größen wie Löslichkeit, Einschluss-, Zersetzungs-, Lösungs- und Kristallisationsenthalpien konnten neue Erkenntnisse bezüglich der Struktur-Eigenschaftsbeziehungen sowie zur Rolle der Wirt-Gast Wechselwirkungen in den existierenden Einschlussverbindungen abgeleitet werden. Die Einschlussbildung bzw. Kristallisation verläuft für alle untersuchten Clathratphasen exotherm. Dies bedeutet, dass die Einschlussverbindungen gegenüber dem reinem Wirt energetisch stark begünstigt sind. Der bestimmende Beitrag hierfür resultiert aus der Bildung eines optimal gepackten Kristallgitters, während spezifische Wirt-Gast Wechselwirkungen nur eine untergeordnete Rolle spielen. Das Zersetzungsverhalten der verschiedenen Clathratphasen kann widerspruchsfrei aus der Packungsstruktur der Kristalle erklärt werden.
280

Application of resting-state fMRI methods to acute ischemic stroke

Lv, Yating 26 September 2013 (has links)
Diffusion weighted imaging (DWI) and dynamic susceptibility contrast-enhanced (DSC) perfusion-weighted imaging (PWI) are commonly employed in clinical practice and in research to give pathophysiological information for patients with acute ischemic stroke. DWI is thought to roughly reflect the severely damaged infarct core, while DSC-PWI reflects the area of hypoperfusion. The volumetric difference between DWI and DSC-PWI is termed the PWI/DWI-mismatch, and has been suggested as an MRI surrogate of the ischemic penumbra. However, due to the application of a contrast agent, which has potentially severe side-effects (e.g., nephrogenic systemic fibrosis), the DSC-PWI precludes repetitive examinations for monitoring purposes. New approaches are being sought to overcome this shortcoming. BOLD (blood oxygen-level dependent) signal can reflect the metabolism of blood oxygen in the brain and hemodynamics can be assessed with resting-state fMRI. The aim of this thesis was to use resting-state fMRI as a new approach to give similar information as DSC-PWI. This thesis comprises two studies: In the first study (see Chapter 2), two resting-state fMRI methods, local methods which compare low frequency amplitudes between two hemispheres and a k-means clustering approach, were applied to investigate the functional damage of patients with acute ischemic stroke both in the time domain and frequency domain. We found that the lesion areas had lower amplitudes than contralateral homotopic healthy tissues. We also differentiated the lesion areas from healthy tissues using a k-means clustering approach. In the second study (see Chapter 3), time-shift analysis (TSA), which assesses time delays of the spontaneous low frequency fluctuations of the resting-state BOLD signal, was applied to give similar pathophysiological information as DSC-PWI in the acute phase of stroke. We found that areas which showed a pronounced time delay to the respective mean time course were very similar to the hypoperfusion area. In summary, we suggest that the resting-state fMRI methods, especially the time-shift analysis (TSA), may provide comparable information to DSC-PWI and thus serve as a useful diagnostic tool for stroke MRI without the need for the application of a contrast agent.

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