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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.
1

Study on anti-adhesion layer of nanoimprint

Wang, Zhao-Kai 06 September 2010 (has links)
In this study, it was nanoimprint focused on the anti-adhesion technique between the grating structure silicon molds below 200nm half-pitch and polymer materials (H-PDMS). The nano-groove structure molds with different depths and widths were made by FIB. During the process of molding by soft-lithography, an anti-adhesion layer needed being plated between the silicon and PDMS mold, which was in order to get completely formed H-PDMS soft mold and prevent defective mold caused by the adhesion problem on the surface. There were three kinds of method of plating anti-adhesion layer which were the liquid immersion, vapor deposition, and fluorine doped DLC film. The PFOTCS was used as mold releasing agent in the methods of liquid immersion and vapor deposition, and the contact angle was measured to realize the ability of anti-adhesion. In the method of fluorine doped DLC film, in addition to measuring the anti-adhesion ability for each sample through contact angle with water, the AFM was also applied to measure the degree of adhesion on the surface for each film. And the contact angles with water between each film were also compared. The methods of plating anti-adhesion film with lower degree of adhesion on the surface could be acquired and discussed by means of the above-mentioned ways to fabricate the molds with good formability
2

Stability of Self-Assembled Monolayer Surfactant Coating in Thermal Nanoimprint

Lunsford, Patrick 2010 December 1900 (has links)
High-resolution and low-cost fabrication techniques are essential for nanotechnology to overcome the commercialization barrier to benefit our society. Since its inception nanoimprint has become the ideal technology to fabricate dense sub-micron structures over large areas with low cost, which are important to many applications such as high-density storage disks and diffractive optical devices. The decade-long development in nanoimprint equipment has reached a point where large-scale manufacturing of high-density nanostructures are possible. However, there are a few remaining issues that need to be studied before the advent of commercial application of nanoimprint. In this work we look at a pressing issue, long-term stability of the mold surfactant coating. It is important to understand the details of the surfactant wear during nanoimprint in order to limit defect density to a tolerable threshold in a high-volume manufacturing process. To study this we went through a nanoimprinting procedure and measured chemical and physical alterations in the coating. The surfactant wear information also helps to optimize the time interval for surfactant recoating to keep the fabrication throughput as high as possible. In this paper we characterize the stability of two commonly used surfactants as well as prescribe a new technique for mold anti-adhesion. Through this work we see that FDTS and OTS undergo significant degradation in air and gradual degradation by chain scission is observed during the nanoimprint procedure. It is also noted that an embedded anti-adhesion layer is effective for mold releasing.
3

Investigating the inhibitory effects of cranberry juice metabolites on uropathogenic Escherichia coli for the prevention of urinary tract infections

Zhang, Yuxian 21 August 2011 (has links)
"Regular ingestion of American cranberry (Vaccinium macrocarpon) has been traditionally utilized for its health benefits against urinary tract infections. The proanthocyanidins (PACs), in particular, the unique A-type double linkages of PACs present in cranberry, have been identified as the active components. However, A-type PACs and any other active agents have not yet been detected or identified in urine. Additional experiments are required to investigate the inhibitory effects and persistence of cranberry metabolites present in urine collected following CJC consumption, and to determine how these compounds act against uropathogenic Escherichia coli for the prevention of urinary tract infections. Two separate bioassays (a biofilm formation assay and a bacterial cell viability assay) were used to determine the in vitro effect of cranberry juice cocktail (CJC) oral consumption on bacterial anti-adhesion activity in a double-blind, placebo-controlled pilot clinical trial. A single dose of 16 oz. of CJC or a placebo beverage was given to ten healthy women, ages ranging from 18 to 27, and urine samples were collected in the following 48 hours. A washout period of seven days was allowed. Bacteria (Escherichia coli B37, CFT073, BF1023, HB101, and Staphylococcus aureus ATCC43866) were cultured in the urine samples, supplemented with media, and the amount of biofilm formed was measured using a crystal violet absorbance assay in a 96-well plate. In the urine of volunteers who had consumed CJC, biofilm formation was inhibited within 24 hours after CJC consumption, and started to increase after 48 hours by 49-67%. S. aureus showed the least biofilm formation after incubation with post-CJC urine. The results indicated that drinking CJC can be an effective preventive measure for bacterial adhesion and biofilm formation in healthy women. The anti-biofilm activity peaks between 24 and 48 hours after drinking CJC. The viability assay showed that the colony count after culturing in urine collected following consumption of CJC or placebo were not significantly different, implying that CJC works as an inhibitor by blocking bacterial adhesion instead of killing the bacteria or restraining its growth. Another randomized, placebo-controlled, double-blind, crossover study was conducted to further investigate the molecular-scale effect of cranberry juice metabolites on two P-fimbriated E. coli strains: B37 and CFT 073, as assessed by atomic force microscopy (AFM). Three female subjects were asked to consume 8 oz. CJC or water. The washout period was 7 days. The urine samples were collected at 2, 4 and 6 hours post-ingestion of CJC or water. Urine collected before consumption of CJC was used as a control. For this control urine, the average adhesion force between E. coli and uroepithelial cells was 13.09 ± 11.60 nN for CFT073 and 10.30 ± 5.50 nN for B37. For post-CJC urine treatment, the adhesion forces decreased to 2.94 ± 1.82 nN at 2 hours after consumption then increased slightly to 5.51 ± 2.78 nN at 6 hours after ingestion for CFT073, while they decreased to 4.77 ± 3.33 nN after consuming for 2 hours and seemed to be stable in the next 4 hours following consumption (5.52 ± 4.04 nN after drinking for 4 hours; 5.05 ± 4.42 nN after drinking for 6 hours) for B37. The adhesion forces in post-water consumption urine were similar to those of the background for E. coli B37; meanwhile a downward trend for the adhesion forces in post-water consumption urine compared to the background was observed for E. coli CFT073. However, these adhesion forces in post-water consumption urine were still higher than those measured after CJC consumption at the same time intervals. The mean differences between the cranberry and placebo groups were statistically different according to the two way ANOVA procedure followed by Holm-Sidak test. Our results suggest a significant inhibitory interaction between the daily consumption of 8 oz. cranberry juice and bacterial adhesive activity. These results help form the mechanistic understanding of how cranberry products can be used to prevent bacterial attachment to host tissue, and may lead to new therapeutic strategies to prevent the rising problem of bacteria antibiotic resistance.  "
4

Médiation chimique entre l’algue brune méditerranéenne Taonia atomaria et la communauté bactérienne associée à sa surface / Chemical mediation between the brown Mediterranean alga Taonia atomaria and its associated bacteria

Othmani, Ahlem 20 January 2014 (has links)
Dans le milieu marin, toute surface immergée est rapidement colonisée par des bactéries, puis par d’autres micro-organismes, conduisant à la formation de structures tridimensionnelles complexes appelées biofilms. Cette étape est généralement suivie par l’installation de macro-colonisateurs. Néanmoins, un certain nombre d’organismes marins, tels que les macro-algues, présentent des surfaces peu épiphytées à l’échelle macroscopique. Des algues méditerranéennes (Taonia atomaria et Dictyota spp.) ont été sélectionnées dans le cadre de ces travaux de thèse pour leur capacité à conserver leur surface peu colonisée. Cependant, des observations de leurs surfaces par microscopie ont montré l’existence de biofilms diversifiés à la surface de leurs thalles. Le but de cette thèse est de mieux comprendre les mécanismes de médiation chimique entre ces algues et les bactéries associées à leur surface. La première partie de ce travail a été consacrée à l’étude du rôle de molécules d’origine algale vis-à-vis de l’adhésion de bactéries marines. Pour cela, la composition chimique totale des algues sélectionnées a été analysée conduisant à l’isolement et à la caractérisation structurale de 12 molécules, dont trois se sont révélées être originales. L’activité anti-adhésion de la majorité de ces composés a ensuite été évaluée : le 1-O-octadecenoylglycérol s’est avéré être le produit le plus actif (20 µM < CE50 <55 µM). La deuxième partie a été dédiée plus particulièrement à l’étude du métabolome de surface de T. atomaria dans le but d’évaluer son implication dans les interactions écologiques entre l’algue et les bactéries associées à sa surface. Un protocole d’obtention et d’analyse spécifique des extraits surfaciques a tout d’abord été développé. Ce protocole est basé sur le trempage des thalles dans des solvants organiques et un contrôle de l’intégrité des cellules membranaires des algues y est associé. L’échantillonnage a été effectué mensuellement à Carqueiranne (Nord-ouest de la Méditerranée, France) durant la période allant de février à juillet 2013. Les résultats obtenus montrent qu’un sesquiterpène est exprimé majoritairement à la surface de l’algue. Il a été démontré que ce composé inhibe l’adhésion de souches bactériennes de référence tout en restant inactif vis-à-vis de celles isolées à la surface de l’algue. Une telle spécificité n’a pas été observée ni dans le cas de biocides commerciaux, ni pour les autres métabolites produits par T. atomaria. Dans un second temps, un suivi saisonnier des extraits de surface ainsi que des communautés bactériennes associées a été effectué par métabolomique (LC-MS) et DGGE, respectivement. Des fluctuations saisonnières de ces deux paramètres ont été reportées sans mettre en évidence de corrélation évidente entre eux. La présence de la molécule majeure de surface durant tout le suivi saisonnier a été notée ainsi que sa capacité à diffuser dans l’eau de mer. Enfin, l’étude de l’implication potentielle des bactéries associées à T. atomaria dans le contrôle du biofilm a été entreprise en évaluant l’activité de leurs extraits vis-à-vis de l’adhésion de souches de référence. En conclusion, nous émettons l'hypothèse que T. atomaria pourraient contrôler partiellement le biofilm associé à sa surface en faisant intervenir des métabolites spécifiques. / In the marine environment, all submerged surfaces are rapidly colonized by bacteria and other microorganisms, resulting in the formation of complex three-dimensional structures called biofilms. This step could be followed by the attachment of macro-colonizers. Nevertheless, a number of marine organisms, such as macro-algae, appeared to be relatively free of epibionts at a macroscopic scale. In this study, several Mediterranean algae (Taonia atomaria and Dictyota spp.) were selected for their ability to keep their surface free of biofouling. However, microscopic techniques allowed the observation of a diversified biofilm on the surface of their thalli. The purpose of this work was to understand how this alga could interact with its associated bacteria using a chemical ecological approach. The first part of this work deals with studying the anti-adhesion properties of algal molecules against a range of marine bacteria. For this, the whole chemical composition of the two algae was analyzed leading to the isolation and structural characterization of 12 molecules from which three were found to be new. The anti-adhesion activity of some of these compounds was then evaluated: 1-O-octadecenoylglycerol proved to be the most active product (20 µM < EC50 <55 µM). The second part of this study was dedicated to the study of the surface metabolome of T. atomaria in order to assess its involvement in the ecological interactions between the alga and its associated bacteria. A specific extraction protocol was optimized for the surface compounds using a dipping technique in organic solvents associated with the integrity control of algal cell membrane. Sampling was carried out monthly at Carqueiranne (N W Mediterranean Sea, France) between February and July 2013. The results showed the presence of a major molecule in accordance with a sesquiterpenic structure. Anti-adhesion capacity against reference bacterial strains was noticed for this compound, while it remained inactive against strains isolated from the algal surface. This specificity was not observed for commercial biocides and the other molecules purified from crude algal extracts of T. atomaria. Then, changes in surface extracts and associated bacterial surface communities were monitored using metabolomics (LC-MS) and DGGE, respectively. Seasonal fluctuations for the two parameters could be reported without any evident correlation between them. The occurrence of the major molecule throughout the seasonal monitoring was also noticed and its capacity to diffuse in the marine environment was shown. Finally, the study of the potential involvement of the associated bacteria in the biofilm control was conducted by evaluating the anti-adhesion activity of their crude extracts against reference strains. In conclusion, we hypothesize that T. atomaria could control at least partially the biofilm at its surface using specific metabolites.
5

Mechanistic Validation of Potential Anti-Breast Cancer Therapeutics

Chuang, Hsiao-Ching 27 June 2012 (has links)
No description available.
6

Elaboration d'un dispositif médical contenant une association d'actifs naturels innovants dans le but de prévenir l'escarre / Development of a medical device containing a combination of innovative natural actives in order to prevent bedsores

Garcia, Cédric 22 June 2016 (has links)
Dans le cadre d’une hospitalisation, l’escarre est un souci majeur aussi bien pour le confort des patients que d’un point de vue économique. Le vieillissement de la population confronte de plus en plus le personnel soignant à la prévention et au traitement des escarres. La prophylaxie n’en est donc que plus essentielle dans les milieux hospitaliers. Force est de constater qu’il existe en la matière peu de produits spécialisés dont l’efficacité a été éprouvée. En partenariat avec le laboratoire RIVADIS, nous avons donc voulu élaborer un système galénique contenant une association d’actifs naturels innovants afin de prévenir l’escarre. Un état de l’art complet a été effectué sur la thématique des escarres afin d’en comprendre tous les facteurs de risques. Par la suite, une recherche approfondie a permis de sélectionner les plantes et molécules pouvant être utilisées comme actifs dans la prévention et/ou le traitement de cette pathologie. Notre attention s’est particulièrement attardée sur le pouvoir anti-inflammatoire, cicatrisant, antioxydant et anti-adhésion bactérienne de ces actifs. Les deux meilleurs actifs obtenus sont la pectine de pomme et l’extrait sec de Centella asiatica L., dont les résultats se sont avérés significatifs sur au moins trois propriétés recherchées. L’étude des effets combinés de ses deux actifs a même montré une synergie sur le pouvoir anti-adhésion bactérienne. Ils ont alors été incorporés sous forme galénique, de façon à rendre possible la réalisation d’un effleurage aussi facile que celui permis par les huiles déjà présentes sur le marché tout en autorisant l’incorporation d’actifs hydrophiles. / In the case of a hospitalization, bedsores are a major issue regarding the comfort of the patient as well as economical reasons. Due to the aging population, the nurses are more and more confronted to prevention and treatment of bedsores. Thus, prevention is now considered as essential in hospitals. It must be noted that in matter of bedsores, there exist only a few specialized products which efficiency has been proved. Therefore, in association with RIVADIS Laboratory, we planed to work on a galenic formulation which contains a combination of innovative natural active. A complete compilation of specialized publications on this topic has been realized in order to fully understand all the risk factors. Then, thanks to an extensive research, we identified the plants and molecules that could be used as actives for the prevention and/or treatment of this pathology. We focused on their anti-inflammatory, healing, antioxidant and bacterial anti-adhesive properties. The two best actives thus obtained are apple pectin and dry Centella asiatica L. extract, they present significant results on at least three of the four wanted properties. Studying the combined effects of these two actives even showed a synergy on bacterial anti-adhesive property. They have then been incorporated in a galenic formulation that makes the massage as easy as the one allowed by already commercialised oils and enables the incorporation of hydrophilic actives.
7

Espinélios do sistema Mg2TiO4-Mg2SnO4 obtidos pelo método Pechini-modificado: propriedades fotocatalíticas e antiadesão microbiana / Mg2Ti1-xSnxO4 spinels obtained by the modified-Pechini method: photocatalytic properties and microbial anti-adhesion

Lima, Laís Chantelle de 29 February 2016 (has links)
Submitted by ANA KARLA PEREIRA RODRIGUES (anakarla_@hotmail.com) on 2017-08-07T12:48:06Z No. of bitstreams: 1 arquivototal.pdf: 4672568 bytes, checksum: 30655ee26e612b43221335d08bddc500 (MD5) / Made available in DSpace on 2017-08-07T12:48:06Z (GMT). No. of bitstreams: 1 arquivototal.pdf: 4672568 bytes, checksum: 30655ee26e612b43221335d08bddc500 (MD5) Previous issue date: 2016-02-29 / Conselho Nacional de Pesquisa e Desenvolvimento Científico e Tecnológico - CNPq / Magnesium stannate (Mg2SnO4) and titanate (Mg2TiO4) are inverse spinel-type oxides, applied as humidity sensors, hot resistor, dieletric, temperature compensation capacitor, electronic ceramic and refractory material. In the present work, these two materials were combined in order to obtain a solid solution, Mg2(Ti1-xSnx)O4, (x = 0; 0,25; 0,50; 0,75; 1,0) by the modified-Pechini method, in order to investigate the influence of Sn4+ substitution for Ti4+ in the spinel lattice for application as photocatalyst for discoloration of Gold yellow remazol and to avoid micro-organism adhesion into surfaces. The synthesis of the spinels was optimized. Catalysts were characterized by X-ray diffraction, UV-visibe spectroscopy, Raman spectroscopy, infrared spectroscopy, surface area measurement using BET method. Mg2TiO4 is a metastable compound, which decomposes into ilmenite (MgTiO3) above 800 °C. On the other hand, reaches long-range order at lower temperatures, while single phase Mg2SnO4 is only obtained from 900 °C. For these reasons, different temperatures are necessary to obtain the single phase materials. Infrared and Raman spectra confirmed the presence of [MgO6]-10, [TiO6]-8, [SnO6]-8 octahedra and (MgO4)-6 tetrahedra. The photocatalytic tests were carried out in a reactor comprising of UVC lamp (λ = 254 nm). Mg2SnO4 presented the best photocatalytic result, with 79% of discoloration at pH 6 and 87% at pH 3, while Mg2TiO4 showed 7% of conversion at pH 6, without increasing efficiency at pH 3. The obtained spinels were effective in inhibiting bacterial and fungal growth as indicated by fluorescence analysis for Gram positive bacteria (S. aureus and S. mutans), Gram negative bacteria (P. aeruginosa and E. coli) and fungus (Candida albicans) showing the potential for microbial anti-adhesion material. Tests with higher titanium content showed the best results except for E. coli. / O estanato (Mg2SnO4) e o titanato de magnésio (Mg2TiO4) são óxidos do tipo espinélio inverso, aplicados como sensores de umidade, resistor de calor, dielétrico, capacitor para compensação de temperatura, cerâmica eletrônica e material refratário. Nesse trabalho, os dois materiais foram combinados com a finalidade de obter uma solução sólida, Mg2(Ti1-xSnx)O4, (x = 0; 0,25; 0,50; 0,75; 1,0), utilizando o método Pechini modificado, de modo a investigar a influência da substituição dos íons Sn4+ por íons Ti4+ na rede do espinélio para aplicação como catalisadores na descoloração do corante remazol amarelo ouro e na antiadesão microbiana. A síntese dos espinélios foi otimizada. Os catalisadores foram caracterizados pelas técnicas de difração de raios-X, espectroscopia na região do ultravioleta e do visível, e espectroscopia Raman, espectroscopia na região do infravermelho e medida de área superficial por BET. O Mg2TiO4 é um composto metaestável, se decompondo em ilmenita (MgTiO3) acima de 800 °C. Por outro lado, o Mg2TiO4 se organiza a longo alcance em temperaturas mais baixas enquanto que o Mg2SnO4 monofásico é obtido apenas a partir de 900°C. Com isso, observa-se que diferentes temperaturas são necessárias para se obter os materiais monofásicos. Os espectros de IV e Raman confirmaram a presença dos octaedros [MgO6]-10, [TiO6]-8, [SnO6]-8 e tetraedro (MgO4)-6. Os testes fotocatalíticos foram realizados em um reator composto por lâmpadas UVC (λ = 254 nm). O Mg2SnO4 apresentou o melhor resultado, com descoloração de 79 % em pH 6 e 87 % em pH 3, enquanto o Mg2TiO4 apresentou conversão de 7 % em pH 6, sem aumento de eficiência em pH 3. Os espinélios obtidos mostraram-se eficazes na inibição do crescimento bacteriano e fúngico como indicado pela análise de fluorescência para bactérias Gram positivas (S. aureus e S. mutans), Gram negativas (P. aeruginosa e E. coli) e para o fungo (Candida albicans) mostrando o potencial de antiadesão microbiana dos materiais. Os testes com maior teor de titânio apresentaram os melhores resultados exceto para a E. coli.
8

Application of sodium alginate as a medical material aimed to prevent air leak and adhesion / アルギン酸ナトリウムのエアリークと癒着の防止のための医療材料への応用 / アルギンサン ナトリウム ノ エア リーク ト ユチャク ノ ボウシ ノ タメ ノ イリョウ ザイリョウ エノ オウヨウ

的場 麻理, Mari Matoba 22 March 2019 (has links)
手術後の呼吸器からの空気漏出(エアリーク)と腹部及び胸部癒着はそれぞれ、未だに臨床にて大きな課題である。本研究では、安全性に優れた植物性多糖類のアルギン酸ナトリウムに着目し、ゲルやスポンジの材形に加工した。これをPGA不織布と併用して新規エアリーク防止材を開発した。この新規材料は、エアリーク防止だけでなく癒着防止に対しても優れた効果を発揮した。将来的に、この新規材料は、従来材料よりも優れた医療材料として臨床応用されることが期待できると考えられる。 / Sodium alginate is polysaccharide extracted from seaweed and used as a biomaterial clinically. The alginate in this study was used as gel- or sponge-formed and combined with a polyglycolic acid (PGA) mesh, a useful biomaterial clinically; namely this combination was the new sealing material. The purpose of this study was to prevent pulmonary air leak without inducing adhesion. This study was composed of the four animal experiments; the first half of them was about preventing air leak and the latter was about preventing adhesion. All experiments showed that new sealing material was superior to the conventional treatments. Therefore the new sealing material was expected to be applied clinically to a sealing material, which also has an anti-adhesive effect. / 博士(理学) / Doctor of Philosophy in Science / 同志社大学 / Doshisha University
9

Muc4 Modulation of Ligand-Independent ErbB2 Signaling

Kozloski, Goldi Attias 04 June 2009 (has links)
The membrane mucin Muc4 is a heterodimer, bi-functional glycoprotein complex that is normally expressed in epithelial tissue. Functional studies on the extracellular mucin subunit of Muc4 have shown that it acts to promote anti-adhesion properties by sterically interfering with cell-cell and cell-matrix interactions and that the extent of this effect is directly associated with the number of tandem repeats on this subunit. Functional studies on the transmembrane subunit of Muc4 have shown that this subunit participates in intracellular signaling through interaction with the receptor tyrosine kinase ErbB2. This role of Muc4 was shown to be mediated by stabilizing the heregulin ligand-induced ErbB2-ErbB3 heterodimer through interference with the internalization process of these receptors, thus potentiating the PI3K, a survival-signaling pathway that is mediated by this heterodimer. However, Muc4 was also shown to potentiate ErbB2 phosphorylation in the absence of heregulin by an unknown mechanism. The aim of this work was to examine the role of Muc4 in intracellular signaling by evaluating the ligand-independent Muc4-ErbB2 interaction. Biochemical analyses of A375 human melanoma cells expressing Muc4 under different cell treatments, and probed with phospho-specific antibodies, were used to understand the mechanism. An antibody microarray screen was used to decipher the intracellular activated signaling pathways. The results of the mechanistic analysis indicated that Muc4 potentiates ErbB2 signaling significantly by interacting with ErbB2 and ErbB3 and by stabilizing the kinase active ErbB2 receptor, thus increasing its phosphorylation signal half-life and resulting in sustained ErbB2 signaling. The signaling pathway analysis suggests that through Muc4 direct interaction with ErbB2, signaling pathways that promote loss of cell polarity are activated. Loss of cell-cell adhesion is mediated by interference with the cadherin-catenin complex stability, and loss of cell-matrix adhesion is mediated by facilitating focal adhesion turnover. Together, these results suggest that Muc4 is a potent oncogenic factor, and further enhance our understanding of the role that Muc4 plays in ligand-independent intracellular signaling.
10

STRATEGIES FOR SUSTAINED RELEASE OF SMALL HYDROPHILIC DRUGS FROM HYDROGEL BASED MATRICES

Wang, Qing January 2017 (has links)
No description available.

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