89 research outputs found
Chromatographic Examinations of Tea's Protection Against Lipid Oxidative Modifications
Ethanol metabolism is accompanied by generation of free radicals that damage cell components, especially lipids. The present study was designed to investigate the efficacy of the preventive effect of black tea on the lipid oxidative modifications in different tissues (plasma, liver, brain, kidney, stomach, lung, intestine, and spleen) of 12-month-old rats chronically intoxicated with ethanol. Ethanol intoxication caused changes in the level/activity of antioxidants that led to the significant increase in the level of lipid oxidative modification products. Oxidative modifications were estimated by measuring lipid hydroperoxides, malondialdehyde, and 4-hydroxynonenal by high-performance liquid chromatography (HPLC) and by spectrophotometric determination of conjugated dienes. These lipid-modification marker levels were increased in almost all examined tissues (3%ā71%) after ethanol intoxication. Described changes were in accordance with the liver level of the most often used marker of arachidonic acid oxidation, isoprostane (8-isoPGF2Ī±), determined by the LC/MS system. Administration of black tea to ethanol-intoxicated rats remarkably prevents the significant increase (by about 15%ā42%) in concentrations of all measured parameters regarding all examined tissues, but especially the plasma, liver, brain, stomach, and spleen. The preventive effect of black tea in the other organs (kidney, lung, intestine) caused a decrease in examined markers in a smaller degree (by about 7%ā28%). To determine in the liver the major constituents of black tea mainly responsible for antioxidative action such as catechins and theaflavins, which were absorbed in organism, the present study indicates their protective effect against ethanol-induced oxidative modifications of lipids
Primjena i kompozicija individualiziranih zaÅ”titnih elemenata linijske grafike u projektiranju novÄanica
Proces stvaranja novÄanica je dugotrajan i složen, Å”to rezultira kompleksnim rjeÅ”enjima koja predstavljaju pravo remek djelo grafike. NovÄanice su prožete brojnim detaljima i prenose razliÄite informacije koje se analiziraju u teorijskom dijelu rada.
Prvotno se postavljaju kriteriji po kojima se izraÄuje detaljna analiza velikog broja zaÅ”titnih i konceptualnih elemenata na primjerima novÄanica. Time je prikazan okvirni povijesni pregled razvoja novÄanica i utjecaji kojima je bio izložen. Analizira se meÄuovisnost dizajna o sigurnosnim znaÄajkama, te se ispituje razina informiranosti javnosti o zaÅ”titama na novÄanicama. ZakljuÄuje se koje metode zaÅ”tite su najuÄinkovitije, te kako Å”ira javnost najÄeÅ”Äe provjerava autentiÄnost novÄanica.
U eksperimentalnom dijelu rada se na temelju donesenih zakljuÄaka iz teorijskog dijela izraÄuje prototip novÄanice koja je u najveÄoj mjeri prožeta individualiziranim PostScript programskim rjeÅ”enjima elemenata linijske grafike (rozete, mikrotekst, zaÅ”titne linije, brojevi apoena), a od ostalih zaÅ”tita modeliran je individualizirani raster transformacijom matematiÄkog izraza u PostScript programski kod. Sve ostale zaÅ”tite tipiÄne za novÄanice simulirane su alatima za rastersku i vektorsku grafiku. U radu se ispituje utjecaj kompozicije zaÅ”titnih elemenata na prepoznavanje autentiÄnosti novÄanica, te efikasnost samih individualiziranih programskih rjeÅ”enja
- ā¦