Spelling suggestions: "subject:"[een] UV"" "subject:"[enn] UV""
191 |
Contamination de moules (mytilus sp.) en milieu marin par des substances pharmaceutiques et produits de soin / Contamination of mussels (mytilus sp.) in marine environment by pharmaceuticals and personnel care productsBachelot, Morgane 08 July 2010 (has links)
Les substances pharmaceutiques et les produits de soin utilisés pour la protection de la santé humaine sont retrouvés dans tous les compartiments du milieu aquatique. Certaines de ces substances présentent des caractéristiques physico-chimiques ou pharmacologiques suggérant une capacité à se bioaccumuler comme les filtres UV EHMC et OC aux log Kow supérieurs à 5 ou les benzodiazépines diazépam et tétrazépam aux log de Kow de 2,82 et 3,20. L'objectif de ce travail de thèse a été d'évaluer la contamination des moules par 3 filtres UV et de 2 benzodiazépines. Pour cela, une méthode analytique a été mise au point et validée pour le dosage de ces substances dans les moules. Le dosage de l'EHMC et de l'OC a montré qu'en milieu côtier la contamination des moules in situ provient majoritairement des activités récréatives en période estivale et que cette contamination est augmentée dans des zones semi-fermées. Des expérimentations de bioaccumulation sur ces deux substances ont montré que les moules ne bioaccumulent pas ces filtres UV ; elles reflètent les niveaux de contamination en temps réel. Les niveaux de benzodiazépines dans les moules ne sont pas détectables en milieu côtier. Des expérimentations en conditions contrôlées ont montré que les moules absorbent les benzodiazépines. Cependant, elles les éliminent et probablement les métabolisent. L'utilisation de moules pour l'étude de la contamination par des substances émergentes permet l'identification de zones ou de périodes à risque élevé. / Pharmaceutical and personal care products used for human health protection are detected in all aquatic ecosystems. Among them, some compounds have physico-chemical or pharmacological properties that suggest a bioaccumulation capability. It’s the case of the UV filters, EHMC and OC, with log Kow higher than 5 or pharmaceuticals like diazepam and tetrazepam, with log Kow higher than 2.82. The aim of these Phd works was to assess marine mussels contamination for UV filters and benzodiazepines. So, a new analytical method was developed and validated for the determination of these compounds in mussels. EHMC and OC analysis realized in mussels sampled in French coastal waters showed that mainly contamination came from recreational activities in summer season, and that semi-closed areas were more contaminated. Moreover, laboratory experiments showed that mussels had clearly not bioaccumulate these 2 UV filters. Contamination levels in mussels are controlled by water concentrations. Conversely, benzodiazepines were not detected in coastal mussels. However, laboratory experiments showed an accumulation of benzodiazepines in mussels, suggesting elimination and metabolization means. Mussels are nevertheless usefull bioindicators of marine contamination by emerging compounds, allowing to characterize higher risk areas or periods.
|
192 |
Efeitos da radiação ultravioleta solar em algas de importância econômica da região subantártica do Chile durante a primavera / Effects of ultraviolet solar radiation on economically important algae from Chilean Sub-Antartic region during springNelso Patricio Navarro Martínez 02 December 2011 (has links)
Este trabalho analisou os efeitos da radiação solar UV (UV-A e UV-B) em duas espécies de importância comercial do Chile, Mazzaella laminarioides e Porphyra columbina durante a primavera, período no qual freqüentemente tem sido verificado um aumento de radiação UV-B decorrente da diminuição da camada de ozônio. A interação entre a radiação UV e o suprimento de N foi também investigada. Essa interação estimulou a síntese de aminoácidos tipo micosporinas (MAAs) nas duas espécies, durante a exposição a altas irradiâncias de UV em curtos períodos. Esses resultados sugerem um ciclo diário na síntese desses compostos. A longo prazo (18 dias de cultivo), a adição de diferentes concentrações de NO3 não promoveu diferenças no conteúdo de MAAs e no crescimento de M. laminarioides, sugerindo uma adequação do metabolismo da espécie às condições experimentais. Discute-se a mobilização do N intra-celular para a manutenção da capacidade de fotoproteção das algas. Em geral, a UV-B não promoveu efeitos deletérios no crescimento e na produção de carragenanas em tetrasporófitos e gametófitos de M. laminarioides, o que seria esperado para uma espécie do médiolitoral que está exposta a variações na quantidade e qualidade de radiação solar. Entretanto, observou-se uma resposta diferenciada entre esses estádios em altas intensidades de irradiâncias de PAR e UV-B, sugerindo que gametófitos podem se aclimatar mais rapidamente a mudanças na irradiância solar do que tetrasporófitos. As radiações UV-B e UV-A promoveram alterações ultraestruturais em P. columbina. No entanto, após um período no escuro, foi observada uma recuperação parcial dessas estruturas. A partir dos resultados deste trabalho, pode-se concluir que os níveis de UV-B solar que atingiram a região de Magallanes, Chile, não causaram efeitos negativos para a produção de M. laminarioides. Entretanto, promoveram um grande acúmulo de MAAs em P. columbina, principalmente em experimentos com disponibilidade de nitrogênio. / This work analyzed the effects of solar UV radiation (UV-A and UV-B) on two commercial important species from Chile, Mazzaella laminarioides and Porphyra columbina, during the spring when it has often been reported a ozone layer depletion, and consequently increased UV-B radiation. Additionally, the interactive role of nitrogen supply and UV radiation was also investigated. This interaction stimulated synthesis of mycosporine-like amino acids (MAAs) in both species when exposed to high UV irradiance in short-term cultivation. These results suggest the presence of a daily cycle in the MAAs production. In the long-term (18 days), different concentrations of N supply did not cause differences neither in MAAs content nor in growth, suggesting a metabolic acclimation to the experimental conditions. The shift of intracellular N from photosynthetic pigments to MAAs to maintain the capacity of photoprotection is discussed. In general, the UV-B did not cause differences neither in growth nor in carrageenan production in tetrasporophytes and gametophytes of M. laminarioides, once a intertidal species is exposed to variations in solar radiation quality and quantity. However, differentiated responses between gametophytes and tetrasporophytes were observed in high UV and PAR irradiances, suggesting that gametophytes can acclimate more quickly to solar radiation changes than tetrasporophytes. The UV-B and UV-A radiation promoted ultra-structural changes in P. columbina. However, a partial recovery was observed after a period in dark. Based on these results we concluded that UV-B levels that were reaching Magallanes Region, Chile, did not affect biomass production of M. laminarioides, but promoted a greater accumulation of MAAs in P. columbina when cultivated with N addition
|
193 |
Příprava a využití nanočástic a nanovláken s přírodními UV filtry / Preparation and application of nanoparticles and nanofibres with natural UV filtersPlachá, Monika January 2018 (has links)
The presented diploma thesis is focused on preparation of nanoparticles and nanofibres with natural UV filters. Liposomes with encapsulated aqueous, ethanol and lipid extracts were prepared. Nanofibers from PHB containing lipid extract were prepared too. As a part of this work, an overview of natural sources with potential effects as UV filters were introduced. Moreover, nanoparticles and nanofibers and methods of their characterization were described. Size, polydisperse index and colloid stability of prepared nanoparticles were characterized via DLS. In experimental part aqueous, ethanol and lipid extracts were prepared from roasted coffee, green coffee and cascara. These extracts were spectrophotometrically characterized for the content of polyphenols, flavonoids, antioxidant activity, tannins and their SPF. Liposomes and liposomes containing PHB with these extracts were prepared and the encapsulation effectivity, short–term and long–term stability as well as SPF of nanoparticles were determined. Nanofibers from PHB containing lipid extracts were prepared via electrospinning and forcespinning methods. Prepared nanofibers were examined via FTIR–ATR. Antioxidant activity, short–term and long–term stability were determined spectrophotometrically. From selected nanoparticles, emulsions and gels were prepared and their SPF was also determined. Three types of emulsions with the best SPF were selected and tested on volunteers. Sedimentation stability of emulsions was tested by analytical centrifuge. Finally, cytotoxicity of selected nanoparticles and nanofibers was tested via MTT assay using human keratinocytes.
|
194 |
Tištěný UV senzor na bázi fotoelektrochemického článku / Printed UV senor based on photoelectrochemical cellVičarová, Monika January 2019 (has links)
This thesis deals with the construction of a photoelectrochemical cell, which is used for detection of ultraviolet radiation by means of generated photocurrent in dependence on the intensity of incident radiation. The cell construction is based on a carbon electrode system with a titanium dioxide sensory layer and a UV curable electrolyte. Printing techniques such as screen printing, inkjet printing and pad printing were used to deposit individual layers. Carbon electrodes with sensory layer were studied through profilometric analysis, optical microscopy, and four-point probes. The viscosity of the liquid formulation of uncured electrolyte was characterized by rheometric measurement. Photoelectrochemical properties of the prepared cell for use as a UV sensor were investigated by cyclic voltammetry and chronoamperometry.
|
195 |
Studium kinetiky fotochemických reakcí v tenké tištěné polymerní vrstvě / Kinetic study of photochemical reactions in thin printed layerRudická, Andrea January 2020 (has links)
This diploma thesis deals with a study of kinetics of photochemical reactions in a thin printed polymer layer. The experimental part deals with the composition preparation and layers coating. The prepared layers were exposed and subsequently studied for their colour response to the light. The aim of this work was to prepare a photosensitive layer with a significant colour change between individual doses of radiation, to improve the mechanical resistance of the layers, to adjust the sensitivity of the compositions to UVB radiation and to study the kinetics of the photochemical reaction used.
|
196 |
Fotochemická degradace azobarviv / Photochemical degradation of azo-dyesUhrová, Ivana January 2015 (has links)
The diploma thesis describes monitoring of photocatalytic activity of titanium dioxide thin films and photocatalytic degradation of azo dyes, the degradation was also experimentally researched in thin film with polymer matrix. Suitable dye for construction of optical sensor for UV light was chosen from the rate of the azo dyes fading by UV and VIS light. The bleaching rate of the sensors was influenced by addition of another dye into the composition and also by concentration of photocatalyst, polymer and calibration agents. At the end of this thesis, the reciprocity test of prepared compositions was made.
|
197 |
Optimalizace stanovení rozdělení tenzidu při fázové separaci v systému polymer-tenzid / Optimizing the determination of distribution of surfactant at phase separation in polymer-surfactant systemSátorová, Kateřina January 2015 (has links)
This diploma thesis is focused on the determination of distribution a surfactant at phase separation in polymer-surfactant system. Sodium hyaluronate of three molecular weights was chosen as a polymer, CTAB was used as a surfactant. The experiments were performed in an environment of 0,15 M NaCl. The measurement of the CTAB concentration in samples was based on the formation of coloured complexes of CTAB and picric acid in chloroform. UV-VIS spectroscopy was used for the detection of these complexes. The content of CTAB was determined in four gels of different composition (2% Hya + 200 mM CTAB, 2 % Hya + 50 mM CTAB, 0,5 % Hya + 200 mM CTAB, 0,5 % Hya + 50 mM CTAB). All gels were gradually washed five times with 0,15 M NaCl. The content of CTAB was determined for newly prepared gels and for gels after 2 and 4 months since the preparation. Initial concentrations of CTAB and hyaluronan have greater influence on the distribution of CTAB after phase separation, than the molecular weight of hyaluronan. The content of CTAB in newly prepared gels and after 4 months since preparation is very similar and demonstrates the stability of the system.
|
198 |
3D tvarování keramické suspenze vytvrditelné UV zářením / 3d shaping of UV curable ceramic feedstockMišák, Jiří January 2011 (has links)
Diplomová práce je zaměřena na přípravu koloidních suspenzí, vytvrditelných UV zářením, jenž jsou určeny k 3D tisku komplexních keramických vláknových struktur. Rovněž jsou v práci představeny techniky následného tvarování vytisknutých a vytvrzených struktur. Z hydroxyapatitu ve formě prášku a komponent, vytvrditelných UV zářením, byly vytvořeny pasty, určené k 3D tisku komplexních keramických vláknových struktur a multivrstev. U takto vytisknutých a vytvrzených struktur bylo navíc dosaženo zlepšení kvality povrchu a soudržnosti vláken. Pro výrobu past, určených k 3D tisku, s vhodnými reologickými vlastnostmi je nezbytné důkladné pochopení interakcí mezi částicemi, surfaktantem a monomerní/oligomerní směsí. Za použití lineárních a zesíťujících oligomerů jako disperzního média vznikají po tisku a UV vytvrzení velmi flexibilní vláknové mřížky, které lze dále tvarovat a takto vytvářet rozmanité struktury. Tyto struktury jsou následně slinuty, bez významných vad na povrchu či delaminace vrstev, za vzniku složitých keramických těles. Vysoké kvality povrchu je dosaženo UV vytvrzením vytisknutých struktur v argonové atmosféře, která brání kyslíkové inhibici radikálů v blízkosti povrchu vláken. Výhody kombinace 3D tisku s UV vytvrzováním jsou demonstrovány v této práci za užití dvouvrstvých flexibilních struktur, určených k následným metodám 3D tvarování. Takto vytvořených složitých 3D struktur je jen velmi obtížné, ne-li nemožné, dosáhnout pouze užitím přímého 3D tisku. Na základě této práce může být v budoucnu odvozena univerzální teorie k přípravě past, určených k 3D tisku komplexních keramických struktur pro různé aplikace.
|
199 |
Vliv materiálové báze nátěrových systémů na trvanlivost dřeva / Influence of material base of coating systems onto wood durabilityBednářová, Ilona January 2017 (has links)
The thesis deals with the influence of the base material of the coating systems for wood durability when we exposed them to external conditions. The theoretical part is devoted to wood durability and weather resistance with a detailed description of the tests the durability of coating systems. A substantial part of the theory is devoted to description binder component of the coating material. In the practical part was performed the experiment, which examined the influence of the thickness of the coating system, the type of coating material (paint or lasure) as well as the type of binder (water dispersion with an alkyd or acrylic resin, respectively solution coating system with the alkyd resin). All coating systems were exposed to natural and artificial durability tests. The criterions for evaluation were chosen differences of colours.
|
200 |
Příprava a charakterizace biomateriálů s obsahem aktivních přírodních UV filtrů / Preparation and characterization of biomaterials with natural UV filtresPavelková, Renata January 2017 (has links)
This presented diploma thesis is focuses on preparation and characterization of biomaterials with natural UV filters. The theoretical part is aimed at effects of sunlight on the skin and how to avoid these effects by using cosmetic products. The materials and methods for extraction of lipid part of the selected vegetable and microorganism species and methods for preparation and characterization of nanoparticles and emulsions were characterized. The practical part deals with extraction of lipid part of selected vegetable and microorganism species. The liposome particles with encapsulated active compounds were prepared. The particle size, polydispersity index, colloidal stability, encapsulation efficiency, SPF, antioxidant capacity, phospholipid content and cytotoxic effect on human keratinocytes were observed. These particles were used for preparation of the resulting emulsions. Their protection level on UV light were set and stability were tested by using analytical centrifugation.
|
Page generated in 0.0306 seconds