Search results for "TYR"

Synthesis, Structure and Solvatochromism of the Emission of Cyano-Substituted Oligo(phenylenevinylene)s

2001

Strongly luminescent and highly soluble oligo(phenylenevinylene)s with five benzene rings and cyano groups in different positions of the terminal styrene units were prepared by means of Horner and Knoevenagel reactions. The substitution pattern − cyanide moieties on the vinyl or on the aromatic regions, together with the effect of auxochromic groups − has distinct influences on the electronic spectra, particularly on the fluorescence. Polar solvents induce red shifts and strongly reduce the fluorescence intensity of the vinyl-substituted oligomers. Cyano substitution increases the electron affinity of the oligomers; this effect is more pronounced for molecules with vinyl cyanides and can be…

Organisasjonsendring i Stabæk Fotball : en kvalitativ undersøkelse av Stabæk Fotballs strategiske valg for å overleve som toppklubb

2016

Masteroppgave i idrettsvitenskap - Universitetet i Agder 2016 The purpose of this master thesis has been to locate which strategic choices Stabæk Fotball have made from 2012-2015 in order to survive as a high level football club. The study has an organizational perspective, and the changing processes of the club are analyzed by using the Pettigrew´s (1987) contextualist approach. The problem I wanted to address: Which strategic choices have Stabæk Fotball made to survive as a high level football club? This master thesis is based on a qualitative case study method. The data has been collected mainly by depth interview with five persons, and looking at the accounting of the club´s business as…

Stereoselective aldol reaction catalyzed by a highly recyclable polystyrene supported substituted prolinamide catalyst

2008

Polystyrene supported substituted prolinamide was used as catalyst in the aldol reaction between cyclohexanone or acetone and several substituted benzaldehydes in chloroform/water. This catalyst afforded aldol products in high yields and stereoselectivities, especially in the case of reactions performed with acetone. The catalyst was easily recovered by filtration and reused, after regeneration with formic acid, up to 22 times.

Rifampicin is not an inhibitor of tyrosinase

2022

Rifampicin has been previously described as an inhibitor of tyrosinase (Chai et al., Int. J. Biol. Macromol. 102 (2017) 425–430). However, rifampicin contains a p-diphenol group and compounds with such a moiety have been shown before to reduce tyrosinase-generated o-quinones. Rifampicin also shows strong absorption in a region completely overlapping with the visible absorption band of dopachrome, the oxidation product of L-tyrosine and L-dopa, whose concentration is measured spectrophotometrically in the standard enzymatic assay to monitor the activity of tyrosinase. We have demonstrated that rifampicin is also rapidly oxidized by o-quinones generated from catechols by tyrosinase or by trea…

Degradation of an alkaloid pheromone from the pale-brown chafer, Phyllopertha diversa (Coleoptera: Scarabaeidae), by an insect olfactory cytochrome P…

1999

AbstractThe pale-brown chafer, Phyllopertha diversa, utilizes an unusual alkaloid, 1,3-dimethyl-2,4-(1H,3H)-quinazolinedione, as its sex pheromone. This compound is rapidly degraded in vitro by the antennal protein extracts from this scarab beetle. Demethylation at the N-1 position and hydroxylation of the aromatic ring have been identified as the major catabolic pathways. The enzyme responsible for the pheromone degradation is membrane-bound, requires NAD(P)H for activity and is sensitive to cytochrome P450 inhibitors, such as proadifen and metyrapone. The ability to metabolize this unusual pheromone was not detected in 12 species tested, indicating that the P450 system, specific to male P…

Disumano, troppo umano. La maschera del tiranno e l’antropologia dei filosofi (da Sofocle a Seneca)

2019

Tyranny is often regarded as "a perennial problem" (Boesche 1996) on the basis of its ubiquitous presence in literature. Even more enduring is the problem of how to define human nature, its place in the environment, and its relationship to the divine – a core issue of philosophical anthropology (Pansera 2001, Honenberger 2015). In the present paper, I shall approach the literary construction of the tyrant figure in Greek and Roman tragedy from the holistic perspective of philosophical anthropology. I will focus on three well-known dramas (Sophocles’ Oedipus the King and Antigone and Seneca’s Thyestes) which put great emphasis on the moral and cognitive status of tyrants as “exceptional” hum…

Acid-Labile Surfactants Based on Poly(ethylene glycol), Carbon Dioxide and Propylene Oxide: Miniemulsion Polymerization and Degradation Studies

2017

Partially degradable, nonionic AB and ABA type di- and triblock copolymers based on poly(propylene carbonate) and poly(ethylene glycol) blocks were synthesized via immortal copolymerization of carbon dioxide and propylene oxide, using mPEG or PEG as a macroinitiator, and (R,R)-(salcy)-CoOBzF5 as a catalyst in a solvent-free one-pot procedure. The amphiphilic surfactants were prepared with molecular weights (Mn) between 2800 and 10,000 g·mol−1 with narrow molecular weight distributions (1.03–1.09). The copolymers were characterized using 1H-, 13C- and DOSY-NMR spectroscopy and size exclusion chromatography (SEC). Surface-active properties were determined by surface tension measurements (crit…

Nanocomposites based on polystyrene and POSS molecules: properties and photo-stability

2013

Comparison of Post-Weld Treatment of High-Strength Steel Welded Joints in Medium Cycle Fatigue

2010

This paper presents a comparison of three post-weld treatments for fatigue life improvement of welded joints. The objective is to determine the most suitable post-weld treatment for implementation in mass production of certain crane components manufactured from very high-strength steel. The processes investigated are: burr grinding, TIG dressing and ultrasonic impact treatment. The focus of this investigation is on the so-called medium cycle area, i.e. 10 000-500 000 cycles and very high stress ranges. In this area of fatigue design, the use of very high strength steel becomes necessary, since the stress range can exceed the yield-strength of ordinary structural steel, especially when consi…

Interaction of mushroom tyrosinase with aromatic amines, o-diamines and o-aminophenols

2004

3-Amino-L-tyrosine was found to be a substrate of mushroom tyrosinase, contrary to what had previously been reported in the literature. A series of amino derivatives of benzoic acid were tested as substrates and inhibitors of the enzyme. 3-Amino-4-hydroxybenzoic acid, 4-amino-3-hydroxybenzoic acid and 3,4-diaminobenzoic acid were oxidized by this enzyme, as previously reported for Neurospora crassa tyrosinase, but 4-aminobenzoic acid and 3-aminobenzoic acid were not. Interestingly, 3-amino-4-hydroxybenzoic acid was oxidized five times faster than 4-amino-3-hydroxybenzoic acid, confirming the importance of proton transfer from the hydroxyl group at C-4 position. All compounds inhibited the m…