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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.
11

Pharmakokinetisch/pharmakodynamische Untersuchung zur in vitro Aktivtität von Levofloxacin und Moxifloxacin gegenüber B. fragilis und E. coli in Mono- und Mischkultur

Rossi geb. Hoffmann, Stefanie 30 September 2013 (has links) (PDF)
Bibliographische Beschreibung Pharmakokinetisch/pharmakodynamische Untersuchung zur in vitro Aktivtität von Levofloxacin und Moxifloxacin gegenüber B. fragilis und E. coli in Mono- und Mischkultur Universität Leipzig, Dissertation 92 S., 190 Lit., 25 Abb., 20 Tab., 3 Anlagen Referat: Bei intraabdominellen Infektionen findet sich häufig ein polymikrobielles Erregerspektrum aus fakultativ und obligat anaeroben Bakterien. Natürliches Habitat der dabei am häufigsten isolierten Erreger E. coli und B. fragilis ist der gastrointestinale Trakt. Durch Störungen der Darmwandintegrität und nachfolgendem Eindringen der Bakterien in eine sterile Umgebung, wie beispielsweise der Peritonealhöhle, kann es zur Infektion kommen. Die häufigste Form der intraabdominellen Infektionen ist die sekundäre Peritonitis. Die Therapie erfolgt chirurgisch, begleitet von einer antibiotischen Therapie. Dabei sind Kenntnisse über Wirksamkeit und Empfindlichkeit der Erreger gegenüber den verwendeten Antibiotika von entscheidender Bedeutung. In dieser Arbeit wurden die MHK-Werte von vier B. fragilis und vier E. coli Stämmen für Levofloxacin und Moxifloxacin bestimmt, wobei ein B. fragilis und drei E. coli Stämme resistent gegenüber Levofloxacin und Moxifloxacin waren. Anschließend wurden mit einem in vitro PK/PD-Modell die pharmakodynamischen Effekte von Levofloxacin und Moxifloxacin in Mono- und Mischkulturen von B. fragilis und E. coli untersucht. Die Monokulturversuche mit E. coli Stämmen wurden sowohl unter aeroben als auch anaeroben Bedingungen durchgeführt. Durch die Untersuchung von Aktivität und Wirksamkeit von Levofloxacin und Moxifloxacin in vitro können Aussagen über eine mögliche Verwendung bei intraabdominellen Infektionen getroffen werden. Levofloxacin wirkte auf den sensiblen E. coli Stamm nur unter aeroben Bedingungen bakterizid, nicht jedoch unter anaeroben Bedingungen. Hingegen wirkte Moxifloxacin in aerober und anaerober Umgebung bakterizid auf diesen E. coli Stamm. In den Mischkulturen zeigte Moxifloxacin eine bessere in vitro Aktivität als Levofloxacin, wobei Moxifloxacin allerdings auch nur eine moderate Aktivität hatte. Aufgrund der Ergebnisse könnte Moxifloxacin dennoch eine theraupeutische Option bei der Behandlung intraabdomineller Infektionen bieten. Der Einsatz dieser Substanzen sollte jedoch nicht unkritisch erfolgen.
12

Hydrogenisation of metals

Ngwanakgagane, Sentsho Zelda January 2013 (has links)
>Magister Scientiae - MSc / Transition metals are a group of metals which are light in weight and have high hydrogen solubility. Their interaction with hydrogen is exorthermic and this phenomenon makes them “ideal” candidates for various applications of hydrogen storage systems. This explains why the phenomenon of hydrogen storage in Pd is used as a model for hydrogen storage systems because of the nature of absorption associated with it (like a sponge even at low temperatures). The hydrogenation process can be conducted at either room or high temperatures in a furnace under low pressure-low hydrogen gas concentration-short hydrogenation time (LP-LC-ST) and in intelligent gravimetric analyser under high pressurehigh hydrogen gas concentration-long hydrogenation time conditions. Most of the research on hydrogen storage sytems is based on gravimetric analysis of absorbed and desorbed hydrogen concentration. In this work, a comparison study of the hydrogen content in pure Pd, Pd-Pt coated systems, Pd-Pt alloys, commercially pure Ti and Ti-6Al-4V alloy determined by gravimetric methods and elastic recoil detection analysis (which is based on the detection of recoiled hydrogen after interaction with He+ ions) technique was investigated. The changes in the structural properties and the hydrogen content of the materials when exposed to a hydrogen gas environment for different durations at various system temperatures and pressures will be reported. These changes have an effect on the microstructure of CP-Ti and Ti-6Al-4V alloy and structural properties of all the hydrogenated materials. The results obtained from optical microscopy, scanning electron microscopy, x-ray diffraction, intelligent gravimetric analyser, digital balance, elastic recoil detection analysis and Vickers hardness test, show the following: it is found that hydrogenation of Pd at elevated temperatures (550 ˚C and 650 ˚C) does not yield hydrides under LP-LC-ST conditions. However, at room temperature the absorption of hydrogen occurred faster at the beginning of the process. Furthermore, the absorption of hydrogen increased with pressure where optimum absorption (0.67 wt. % hydrogen concentration) occurred under a system pressure of 2000 mbar. After pressure release, the remaining hydrogen content in the Pd sample was 0.6 wt. %. The Pd-Pt coated system provide hydrogen mobility at 550 and 650 ˚C where hydrides were formed under LP-LC-ST conditions. In addition to the decrease of hydrogen solubility in Pd-Pt alloys with an increase in Pt content, the probability of the alloys to achieve full saturation also decreases with an increase in Pt content under HP-HC-LT conditions. CP-Ti and Ti-6Al-4V alloy absorb substantial amount of hydrogen in the first hour of room temperature hydrogenation under LP-LC-ST conditions but hydrides were not formed. Therefore, under LP-LC-ST conditions at room temperature, Pd is able to store hydrogen in the form of hydrides whereas Ti and Ti-6Al-4V alloy could not. The 550 ˚C is the optimum temperature for hydrogenation of CP-Ti under LP-LC-ST conditions. The Ti- 6Al-4V alloy absorb optimum hydrogen at 650 ˚C under LP-LC-ST conditions. Consequently, the change of microhardness of CP-Ti and Ti-6Al-4V alloy was found to depend on hydrogenation temperature.
13

Influência da dispersão de nanopartículas de paládio na atividade de catalisadores suportados em carvão ativo para síntese de aminas / Influence of palladium nanoparticles dispersion in activity of supported catalyst on active carbon applied in the synthesis of amines

Miranda e Britto, Andréia Gonçalves 12 March 2009 (has links)
Orientador: Fernando Galembeck / Dissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Química / Made available in DSpace on 2018-08-16T14:11:34Z (GMT). No. of bitstreams: 1 MirandaeBritto_AndreiaGoncalves_M.pdf: 3688378 bytes, checksum: 62a326372d2a0139c22b57dd76dbc498 (MD5) Previous issue date: 2009 / Resumo: Dois catalisadores, denominados nesta dissertação por A e B, contendo 9% de paládio suportados em carvão ativado foram produzidos pelo mesmo método em escala industrial, porém em anos diferentes. O catalisador A apresentou uma atividade catalítica de hidrogenação do ácido cinâmico 40% inferior ao catalisador B e a hidrogenação de nitrato para formação de hidroxilamina, conhecido como teste Hyam, 31% inferior. Testes adicionais para caracterização dos dois catalisadores foram realizados, como determinação quantitativa do teor metálico via ICP-OES, área superficial e volume de poros calculados pelas técnicas propostas por Brunauer-Emmett-Teller (BET) e Barrett-Joyner-Halenda (BJH) através da isoterma de N2 e quimissorção de CO. Porém esses resultados foram insuficientes para justificar a diferença de atividade na hidrogenação do ácido cinâmico. Microscopia eletrônica de transmissão foi utilizada para investigar essa diferença catalítica. Com as imagens de campo claro e campo escuro obtidas, foi observado que o catalisador A continha aglomerados de cristalitos de paládio que se correlacionavam com as regiões de oxigênio presentes no carvão obtidas pelas imagens de mapeamento elementar. Porém um maior contraste no mapeamento de oxigênio do catalisador A foi observado confirmando a relação existente entre os grupos oxigenados e a dispersão dos nanocristais de paládio. Com as análises de Temperatura Programada de Dessorção (TPD) e Ponto Isoeletrônico (PI) foi constatado que o carvão A¿ continha grupos oxigenados mais ácidos que o carvão B¿. Estes resultados mostraram que o grau e padrão de oxidação do carvão usado como suporte têm grande importância na morfologia e propriedades finais dos catalisadores. / Abstract: Two catalysts, named in this dissertation A and B, containing 9% of palladium supported on active carbon were produced by the same method in an industrial scale, but in different years. Catalyst A had a catalytic activity of cinnamic acid hydrogenation 40% lower than catalyst B and nitrate hydrogenation to hydroxylamine formation, known as Hyam test, 31% lower. Additional tests for the characterization of the two catalysts were performed, such as metal content by ICP-OES, surface area and pore volume obtained from N2 isotherm and Barrett-Joyner-Halenda (BJH) and Brunauer-Emmett-Teller (BET) techniques and CO chemisorption. However, these results were insufficient to justify the difference in activity of cinnamic acid hydrogenation. Transmission electron microscopy was used in order to investigate this catalytic difference. Through the images of bright field and dark field obtained it was observed that the catalyst A contained clusters of palladium crystallites, which are correlated with the oxygen map present in the carbon obtained by energy-loss spectroscopy imaging (ESI). However, a marked contrast in oxygen map for the catalyst A was observed confirming the existing relationship among the oxygen groups and palladium nanocrystals dispersion. Analysis Temperature Programmed Desorption (TPD) and Isoeletric Point (IEP) measurements were performed on the carbon support and it was verified that carbon A¿ contained oxygen groups which are more acid than those in carbon B¿. These results demonstrated that the degree and oxidation pattern in the carbon used as support has great influence in the morphology and final proprieties of the catalyst. / Mestrado / Físico-Química / Mestre em Química
14

Major cultural commemorations and the construction of national identity in the GDR, 1959-1983

Zell, David January 2018 (has links)
My thesis asks whether cultural commemorations helped the GDR to build a distinct national identity, and examines the role of political and cultural actors involved in them. Covering different strands of German cultural heritage, the aims, implementations and outcomes of anniversary commemorations are investigated as a longitudinal series of case-studies: Schiller (1959); Kollwitz (1967); Beethoven (1970); and Luther (1983). Substantial evidence from largely unpublished sources exposes recurring gaps between the theory and practice of these commemorations, essentially attributable to manifest examples of agency by commemoration stakeholders. Each commemoration produced some positive legacies. But driven mainly by demarcation motives versus West Germany, the appropriation of these German cultural icons as socialist role-models to promote national identity was mostly unsuccessful in three commemorations. Kollwitz was the exception as the GDRˈs claimed linkage to her political life was already undisputed in both German states. These research results are both new and important. They address a gap in both memory studies and GDR history scholarship regarding the relationship between commemorations and national identity. Furthermore, the findings of agency offer an original contribution to historiographical debates, by enhancing a ˈconsensusˈ- /ˈparticipatoryˈ dictatorship model of the GDR in preference to a top-down totalitarian system.
15

The role of programmed death-1 (PD-1) expression in the negative selection of T lymphocytes

Parkman, Julia C 06 1900 (has links)
The immune system must be able to mount a response against pathogens and transformed cells while remaining tolerant to healthy host tissue. A key process for ensuring this self-tolerance is the negative selection of self-reactive thymocytes. Expression of Programmed Death-1 (PD-1), a co-inhibitory member of the CD28 family associated with dampened peripheral immune responses,was found to be upregulated in 20-40% of thymocytes undergoing negative selection in the HYcd4model of thymic development. Although analysis of gene and protein expression directly ex vivo indicates that PD-1- and PD-1+ thymocytes are equally apoptotic, PD-1+ thymocytes appear to be protected from apoptosis in an in vitro stimulation assay. Analysis of HYcd4PD-1-/- mice indicates that thymocytes receive a higher intensity signal in the absence of PD-1. Future work utilizing HYcd4PD-1-/- mice will increase our understanding of the role of PD-1 in thymic negative selection. / Immunology
16

Transition Metal-catalyzed cyclization reaction of enediynes to benzo[b]naphtho[2,1-d]thiophene

Chen, Chiu-Mei 28 June 2012 (has links)
Treatment of thioanisole-substituted aryldiyne with 2 equiv. of N-Iodosuccinimide and 5 mol% of PPh3AuCl and 5 mol% AgSbF6 in refluxing dichloromethane gave 5-iodo benzo[b]naphtho[2,1-d]thiophene in good yields. This method tolerated various functional groups in alkyl and phenyl moiety. We also treatment thioanisole-substituted aryldiyne with 10 mo% of PdX2 and 3 equiv. CuX2 (X= Cl, Br),in reluxing THF gave in 5-position have halogen substitute benzo[b]naphtho[2,1-d]thiophene derivative.
17

none

Ou, Ching-fang 13 July 2005 (has links)
none
18

The role of programmed death-1 (PD-1) expression in the negative selection of T lymphocytes

Parkman, Julia C Unknown Date
No description available.
19

Unactivated Alkyl Chloride Reactivity in Excited-State Palladium Catalysis

Gimnkhan, Aidana 11 1900 (has links)
In the last centuries, transition metal chemistry beсome one оf the mоst іmportant tооls for synthesis of valuable organic compounds and different chemical transformations. In particular, transition metal catalysis are capable of forming novel cross coupling bonds. In this background, photocatalysis was developed later to create new chemical transformations by the irradiation with visible light. In this regard, the combination of transition metal catalysis and photochemistry is a breakthrough in catalysis that has provided impossible transformations in organochemistry. One of the widely available reactants in synthesis are alkyl chlorides. However, it is hard to activate chemically stable C(sp3 )-Cl bond at room temperature. In this study, we overcome this limitation by excited-state palladium catalysis under mild conditions. The reaction goes through the hybrid alkyl-Pd radical as a key intermediate. The procedure provides the synthesis of oxindole and isoquinolinedione derivatives mainly from alkyl chlorides via annulation overcoming its chemical limitations. This work will focus on the generation of alkyl radicals from unactivated C(sp3 )-Cl using simple palladium catalysis
20

A Systematic Review and Meta-Analysis Assessing the Relative Efficacy of Immune Checkpoint Inhibitors Based on PD-L1 Expression Levels

Kwiatkowski, Kathy 10 1900 (has links)
Indiana University-Purdue University Indianapolis (IUPUI) / Purpose: The purpose was to comprehensively assess the impact of PD-L1 expression on the efficacy of immune checkpoint inhibitors on Overall Survival (OS) and Progression-Free Survival (PFS). Methods: A systematic literature search and review was conducted through June 2019. I searched all eligible randomized controlled trials comparing PD-1/PD-L1 monotherapy to an active comparator in adult patients with advanced cancer across multiple tumor types. The Cochrane risk-of-bias tool was used to assess trial quality. A random-effects model was used for the meta-analysis. Heterogeneity was assessed using Cochran Q statistic and I2 test. Publication bias was assessed by visual inspection of a funnel plot and Begg’s test. Results: I identified and included 23 trials involving 14,434 participants. When stratifying PD-L1 positive (+) and negative (-) patients using varying thresholds of expression, a significant group difference was observed at PD-L1 >1% ( p=0.04; PD-L1(+): HR, 0.72; 95% CI, 0.65-0.79; PD-L1(-): HR,0.83; 95% CI, 0.75-0.91), at PD-L1 >10% (p=0.02; PD-L1(+): HR,0.50; 95% CI, 0.38-0.62; PD-L1 (-): HR, 0.74; 95% CI, 0.57-0.90) and at PD-L1>50% (p=0.01; PD-L1(+): HR,0.59; 95% CI, 0.51-0.68; PD-L1(-): HR, 0.93; 95% CI, 0.71-1.15). Across tumor types, both PD-L1(+) and PD-L1(-) patients treated with an immunotherapy had improved OS compared with patients receiving standard care therapies. A PFS benefit was observed and favored patients treated with a PD-1/PD-L1 inhibitor versus standard of care. However, there was significant heterogeneity and the benefit on PFS was not statistically significant between PD-L1(+) and PD-L1(-) groups using varying cut-off levels of PD-L1 expression. No differences between sub-groups of interest including median follow-up time, type of inhibitor, and line of therapy for either PD-L1(+) or PD-L1(-) patients at 1% cut-off were identified. Conclusion: This study supports the use of PD-L1 as a predictive biomarker of improved response to immunotherapies. As thresholds increase and specifically above the 10% PD-L1 expression threshold, patients who were positive for PD-L1 appeared to have better OS compared to those who were negative for PD-L1. Further investigation is needed to assess the clinical usefulness of PD-L1 at various expression levels with improved technologies that have the potential to enhance assay accuracy and precision.

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