Optimization of extraction and characterization of Urtica dioica L. leaf extract for the evaluation of dose-dependent response in experimental hypertension

This doctoral dissertation was focused on the optimization of the extraction parameters to achieve the maximum yield of phenolic compounds in the Urtica dioica L. leaf extracts. The extract with the highest content of phenolic compounds was tested in the model of experimental hypertension to determine its effects on oxidative and hemodynamic status, lipid profile, and biochemical parameters. It was shown that the most abundant phenolic compounds present in extracts of Urtica dioica L. were chlorogenic acid, 2-O-caffeoyl malic acid, and rutin. It was shown that aqueous-methanol is a better solvent for the extraction of phenolic compounds compared to aqueous-ethanol and water. Also, extracts prepared using ultrasound-assisted extraction technique had higher phenolic yields and antioxidant capacities than extracts obtained by maceration. The maximal content of phenolic compounds in the Urtica dioica L. leaf extracts was achieved by ultrasound-assisted extraction with 54% aqueous-methanol and 38 min extraction time. It was shown that the methanol percentage in the extraction solvent significantly affects phenolic yield, unlike the extraction time. Results of in vivo study showed that four-week long treatment with Urtica dioica L. leaf extract decreased arterial pressure and improved systemic oxidative status of spontaneously hypertensive rats, as well as the lipid status by increasing plasma HDL cholesterol and decreasing atherosclerosis-index

Optimizacija ekstrakcije i karakterizacija ekstrakta lista Urtica dioica L. za potrebe ispitivanja dozno-zavisnog odgovora u eksperimentalnoj hipertenziji

Modern life is characteriyed by factors that can significantly contribute to the development of cardiovascular diseases...Savremeni način života karakterišu faktori koji značajno mogu da doprinesu nastanku i razvoju kardiovaskularnih bolesti..

Kitsch in Teaching Art in Primary School

U radu se istražuje koliko učiteljice/učitelji prepoznaju kič u nastavi Likovne kulture. Istraživanje se odnosi na niže razrede osnovne škole. Rad se sastoji od dva dijela. U prvom dijelu upoznajemo kič i njegove karakteristike te područja umjetnosti koja taj pojam zahvaća. Drugi dio rada sadrži prikaz istraživanja čiji je cilj bio utvrditi koliko učiteljice/učitelji znaju o kiču. U istraživanju navedenog problema postavljene su četiri hipoteze. Istraživanje je provedeno pomoću anketa na uzorku od 193 učiteljica/učitelja razredne nastave u osnovnim školama s područja Splitsko-dalmatinske, Dubrovačko-neretvanske, Šibensko-kninske i Zagrebačke županije. Ovim istraživanjem utvrdili smo da učiteljice/učitelji ne poznaju dovoljno problematiku kiča te da bi ga trebale/trebali bolje prepoznavati u učeničkim radovima.The main research problem in this graduation thesis is the amount of teacher’s knowledge of term kitsch in visual art. The research is based on 1 – 4 grades of elementary school. This graduation work is divided into two parts. The first part is based on generally meaning of term kitsch, on its beginning and art’s areas which term contains. The second part contains whole research review which aim was to determine the amount of teacher’s kitsch knowledge. Research had set four hypotheses and it is carried out with surveys based on a sample consisting of 193 teachers of elementary schools from these counties: Splitskodalmatinska, Dubrovačko-neretvanska, Šibensko-kninska and Zagrebačka. Hypothesis which claims that the primary education teachers do not have enough knowledge of term kitsch and that they don’t know to recognize it in student’s work is affirmed

Kitsch in Teaching Art in Primary School

U radu se istražuje koliko učiteljice/učitelji prepoznaju kič u nastavi Likovne kulture. Istraživanje se odnosi na niže razrede osnovne škole. Rad se sastoji od dva dijela. U prvom dijelu upoznajemo kič i njegove karakteristike te područja umjetnosti koja taj pojam zahvaća. Drugi dio rada sadrži prikaz istraživanja čiji je cilj bio utvrditi koliko učiteljice/učitelji znaju o kiču. U istraživanju navedenog problema postavljene su četiri hipoteze. Istraživanje je provedeno pomoću anketa na uzorku od 193 učiteljica/učitelja razredne nastave u osnovnim školama s područja Splitsko-dalmatinske, Dubrovačko-neretvanske, Šibensko-kninske i Zagrebačke županije. Ovim istraživanjem utvrdili smo da učiteljice/učitelji ne poznaju dovoljno problematiku kiča te da bi ga trebale/trebali bolje prepoznavati u učeničkim radovima.The main research problem in this graduation thesis is the amount of teacher’s knowledge of term kitsch in visual art. The research is based on 1 – 4 grades of elementary school. This graduation work is divided into two parts. The first part is based on generally meaning of term kitsch, on its beginning and art’s areas which term contains. The second part contains whole research review which aim was to determine the amount of teacher’s kitsch knowledge. Research had set four hypotheses and it is carried out with surveys based on a sample consisting of 193 teachers of elementary schools from these counties: Splitskodalmatinska, Dubrovačko-neretvanska, Šibensko-kninska and Zagrebačka. Hypothesis which claims that the primary education teachers do not have enough knowledge of term kitsch and that they don’t know to recognize it in student’s work is affirmed

The renewal and development of Croatian agriculture, villages and farms

The authors begin by presenting their own conception of rural and agricultural renewal. They consider that destroyed or damaged facilities should be rebuilt in accordance with the most recent research into social and economic development, i.e. that present efforts at renewal should be directly geared towards rural and agricultural prosperity. The article gives the estimates of losses in the livestock fund, farming and residential buildings, agricultural mechanization, the damage done to agro-industrial complexes and other socially-owned agricultural production and processing firms and other damage. The authors tried to estimate the costs of renewal in spite of the difficulties that make precise calculations impossible. The article continues by presenting possible sources for the renewal of this segment of the economy, the bearers of renewal and its priorities. All these questions demand quick practical answers. To these problems of renewal must also be added the inherited bad agrarian and social structure and all the other consequences of an agrarian policy that for so long neglected the private sector

The Effect of Alkaloids on Fluorescence in Solutions

The quenching of fluorescence of different substances by a series of alkaloids has \u27 been studied. The alkaloids generally exert a quenching action on the fluorescence. In evaluating these effects, in certain cases it is necessary to take into consideration the absorptii. on of exciting light by the molecules of the quencher. The quenching effect of the anions of ailka loid salts should also be taken into account. By .mathematical corrections of experimental data for the absorption of the exciting light and the quenching by anions, the constants and semi-concentrations of quenching are obtained for the cation:ic part of the alkaloid. It may be assumed that the quenching effect of alkaloids involves an external static mechanism, i. e. the formation of molecular compounds between the quencher and the fluorescent substance

The effect of alkaloids on the chemiluminescence of luminol

Istraživana je djelovanje niza alkaloida na kemiluminescenciju luminola (3-aminoftalhidrazida) za vrijeme oksidacione reakcije u prisutnosti klorhemina, odnosno methemoglobina ili kalijevog heksacijanoferata(III) kao aktivatora luminescencije. Fotoelektričnim mjerenjima ustanovljene su vremenske krivulje intenziteta kemiluminescencije za različite koncentracije alkaloida. Pretežno su nađeni efekti gašenja kemiluminescencije utjecajem alkaloida. Očito se radi o stvaranju neaktivnih molekularnih spojeva između aktivatora (hematina) i alkaloida. Jednadžba za kompetitivnu inhibiciju enzimatsko kataliziranih biokemijskih reakcija može se dobro primijeniti na ustanovljene efekte gašenja luminescencije. U prisutnosti heksacijanoferata(III) kao aktivatora luminescencije odnosi su znatno zamršeniji. Neki alkaloidi ne gase tako aktiviranu kemiluminescenciju, drugi je gase tek u znatno većoj koncentraciji, odnosno povisuju jakost luminescencije.The effect of certain alkaloids on the chemiluminescent oxidation of luminol in the presence of chlorochemin, methemoglobin and potassium ferricyanide as activators has been studied. The curves of chemiluminescence (intensity of luminescence vs. reaction time) for various concentrations of alkaloids were obtained by photoelectric measurements. In most cases a quenching effect of alkaloids has been observed. The numerical values of the half concentrations of the quenching effect were determined. It is apparent that inactive molecular compounds are formed by the activator (hematin) and alkaloids. The equation of competitive inhibition of biochemical reactions catalyzed by enzymes - which is in fact identical with Stern Volmer\u27s equation for the quenching of fluorescence by addition of foreign substances - can be applied to the observed effects of quenching. In the presence of potassium ferricyanide as activator of luminescence, the reactions involved are much more complicated. Some of the alkaloids studied do not quench the luminescence activated by potassium ferricyanide. Others produce an activating effect in small concentrations and a quenching effect in higher concentrations only

Optimization of the extraction of antioxidants from stinging nettle leaf using response surface methodology

The aim of this study was to optimize the parameters for the extraction of total flavonoids from stinging nettle leaf. Comparison of the effects of different solvents on total flavonoid content showed that, regardless of extraction time, aqueous methanolicextracts had higher total flavonoid content than did aqueous ethanolic extracts. So, full factorial design and response surface methodology (RSM) were em-ployed to estimate the effects of methanol content (50, 75and 100%) and extraction time (30, 60and 90 min) on the total flavonoid content and antioxidant capacities of the extracts. RSM analysis showed that methanol content in the solvent influenced significantly total flavonoid content and FRAP (ferric-reducing antioxidant power) antioxidant capacity, while extraction time had no significant effect on either of these responses. Extraction parameters for maximal total flavonoid content were estimated to be 69% aqueous methanol and 67 min, and 65% aqueous methanol and 83 min for maximal FRAPantioxidantcapacity. DPPH (2,2-diphenyl-1-picrylhydrazyl) antioxidant capacity was not significantly affected by extraction time or methanol percentage in the solvent

Contribution of dry matter determination in milk

Pravilnik o životnim namirnicama predviđa procjenu kvalitete mlijeka na bazi bezmasne suhe tvari izračunate Fleischmannovom formulom. Budući da je za ovo izračunavanje potrebno poznavati osim specifične težine mlijeka i količinu masti, a Pravilnikom je predviđeno određivanje masti metodom po Gerberu i Röse-Gottliebu, to smo smatrali za potrebno usporediti dobivene rezultate za količinu suhe tvari izračunate po Fleischmannovoj formuli na bazi količine masti određene po obim metodama. Osim toga komparirani su rezultati količine bezmasne suhe tvari dobiveni sušenjem do konstantne mase i rezultati izračunati pomoću tabele dobivene transformacijom Fleischmannove formule (Zonji 1975).Statistical analysis of the results on the amount of dry matter in milk, calculated by Fleischmann\u27s formula on the basis of the amount of fat determined by Gerber\u27s method and the method of Rose-Gottlieb, respectively, has revealed no significant differences (estimation risk p = 0.05) between the values obtained on the basis of the amount of fat determined by either method

Komparativno određivanje refrakcije mliječnog seruma

Za procjenu kvalitete mlijeka, određivanje refrakcije mliječnog seruma zauzima značajno mjesto. Prema našem Pravilniku refrakcija mliječnog seruma izražena refraktometrijskim brojem kod 17,5 °C, ne smije biti manja od 39