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  • Author or Editor: M. Marković x
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Lycopene, the pigment responsible for the characteristic deep red colour of ripe tomatoes and their products, plays an important role in human health. The stability of lycopene in tomato purée during storage was studied. Tomato purée was prepared from tomatoes grown in three different geographical regions of Croatia during two seasons. The samples of tomato purée were stored in the dark at 5, 15 and 25 °C and under light at 25 °C during a period of 6 months with constant monitoring of the changes of lycopene content. At the beginning of the storage there was no statistically significant difference (P<0.05) in lycopene content between the samples and geographic origin, while season significantly (P<0.05) influenced lycopene content. The value of lycopene content in all tomato purée samples significantly decreased (P<0.05) with increasing storage time for all the treatments. Light exposure significantly (P<0.05) facilitated degradation of lycopene.

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Abstract  

The long-lived -radionuclidic impurities in the columns of spent99Mo/99mTc generators one year after the calibration date have been determined by -spectrometry. Three radionuclidic impuritiesfission products (103Ru,106Ru and125Sb) were detected. Also in the majority of samples three radioisotopes of tungsten (181W,185W and188W) were also present. The contents of the impurities were found to vary greatly. According to the activity, energy and half-life, the main contribution to the residual activity in the spent generators is due to the presence of125Sb.

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Authors: K. Marković, I. Krbavčić, M. Krpan, D. Bicanic and N. Vahčić

The lycopene content in pulp and peel of five fresh tomato cultivars, most common on Croatian market, was determined by spectrophotometry and the high-performance liquid chromatography (HPLC). Peels from the raw tomatoes contained more lycopene (expressed on a fresh basis) than the pulps: the ratio was 3.75±1.08 for spectrophotometric and 3.50±0.95 for HPLC measurements. Comparison of the results of lycopene content expressed on a dry weight basis revealed that the peel from raw tomato contains 1.74±0.36 times (spectrophotometry) more lycopene than the pulp as compared to a factor of 1.61±0.24 obtained by HPLC analysis. Fraction of the pulp in a whole tomato was found to vary between 89.9 and 95.2%, while that of tomato peel was between 4.9 and 10.1%. Nutritional habits in Croatia often include tomato-based food, all year around, prepared partlyof whole fresh tomatoes (including peel), partly of industrial tomato products (from which peel is often excluded). This study provides evidence that the peel of one of the most common varieties of tomatoes on Croatian market is richer in lycopene than the pulp and, moreover, that a diet including 100 g of raw tomatoes provides 1.35±0.29 mg lycopene from pulp as compared to 0.35±0.18 mg lycopene from tomato peel. In addition, results of this study will be useful in further attempts to quantify lycopene content of intact, whole tomatoes by means of the nondestructive, photoacoustic method.

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Abstract  

Effects of ethylene content and maleated EPDM content on the thermal stability and degradation kinetics of ethylene propylene diene monomer (EPDM) have been studied using high resolution thermogravimetric analysis (Hi-Res TGA) and Modulated TGA (MTGA). Modulated TGA shows that EPDM degradation is complex, with activation energy of degradation increasing throughout the degradation. Values from both dynamic and constant heating rate experiments are in good agreement with each other and with the literature value. However, the dynamic heating rate experiment shows that if the difference of peak temperature of components in a system is less than 5°C, Hi-Res TGA does not resolve them.

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Authors: M. Ginic-Markovic, N. Choudhury, J. Matisons and D. Williams

Abstract  

A two-pack polyurethane coating was analyzed using thermoanalytical techniques. The curing reaction, monitored using pressure differential calorimetry (PDSC), rheometry and dynamic mechanical analysis (DMA) shows the temperature dependency of activation energy and hence rate of curing. In-situ ATR-FTIR shows the formation of urethane linkage over time. The decomposition behavior carried out under non-isothermal mode using thermogravimetric analysis (TGA) shows bimodal behavior. The activation energies of the initial step (10% decomposition) from both iso and non-isothermal experiments are in very good agreement with each other. The use of dynamic mechanical analysis (DMA) shows the difference in glass transition behavior (T g) and elastic modulus (E') due to the different state of cure. Also the coating exhibits a very broad loss modulus peak (E'') indicating higher energy dissipation with deformation.

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Abstract  

Fission-produced -emitting radionuclidic impurities in eluates obtained by elution of routine (n,f)99Mo/99mTc generators have been determined. Four radionuclidic impurities were identified and quantitatively measured by the method of -spectrometry. The distribution of103Ru,106Ru,125Sb and131I in the eluates was followed. The fraction of the activity which has been desorbed from alumina in the generator column during the lifetime of the generator was determined for earch radionuclide found. The contents of radionuclidic impurities in the eluates were compared with the criteria of radionuclidic purity prescribed by the Pharmacopoeia.

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Authors: M. Ginic-Markovic, N. Roy Choudhury, J. Matisons and N. Dutta

Abstract  

The present investigation focuses on matching cure characteristics of EPDM rubber compound and polyurethane (PU) coating using temperature modulated and pressure differential scanning calorimetry (TMDSC, PDSC). TMDSC provides a detailed and better understanding of the curing process of model rubber system as well as complex automotive rubber compounds. The low level of unsaturation present in EPDM, results in the small heat of vulcanization (2–5 J g–1), which is difficult to accurately measure using conventional differential scanning calorimetry (DSC). Thus, curing of highly filled EPDM compound was investigated using TMDSC. The kinetics of PU curing was monitored using pressure DSC (PDSC), and heat of curing was determined as 4.2 J g–1 at 10C min–1 heating rate. It is found that complex automotive compounds and the PU coating are curing simultaneously.

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Authors: M. Marković, P. Pepó, M. Sárvári, V. Kovačević, J. Šoštarić and M. Josipović

In the decade from 2000 to 2009, the yield of maize grain in Croatia varied from 4.2 t ha−1 (2003) to 8.0 t ha−1 (2008). The yield variation was mainly caused by weather conditions unfavourable for maize production, meaning lack of precipitation, unevenly distributed during the vegetation season, and mean air temperatures above the long-term mean. Irrigation has become a justified and essential agrotechnical measure that minimizes the damage caused by water deficit during critical plant growth stages and ensures high yields with good quality. In this paper two vegetation seasons (2006 and 2007) with quite different weather conditions for maize production were analysed in order to examine the importance of irrigation in terms of yield increase, irrigation water use efficiency (IWUE), irrigation efficiency (IE) and irrigation water use index (IWUI) in years favourable (2006) or too dry (2007) for maize production. The yield surpluses achieved with irrigation ranged from 8.54 t ha−1 to 9.62 t ha−1 in the average crop year (2006) and from 8.43 t ha−1 to 10.7 t ha−1 in the dry year (2007), depending on the irrigation method. In the dry year the values of IWUE where higher than in the average year (6.16 and 13.75 kg ha−1/mm, respectively, averaged over the hybrids).

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Authors: Dj. Čokeša, M. Marković, M. Soleša, P. Adžić, G. Škoro, S. Milonjić and A. Kukoč

Abstract  

Seventeen honey samples collected at different sites during 1992 have been measured using the method of -spectroscopy. Measurements were performed by a low background high purity germanium spectrometer of a relative efficiency of 14.5% and an energy resolution of 1.7 keV. Using natural -ray sources to determine efficiency, it has been shown that out of 17 samples of natural honey only two (of meadow type) have specific activity of137Cs greater than 0.5 Bq kg–1. The remaining samples have the same137Cs concentrations as before May, 1986. Predominant activity in all samples comes from the40K radionuclide, indicating natural honey.

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Authors: Snežana Marković, Jovana Žižić, Ana Obradović, Branka Ognjanović, A. Štajn, Zorica Saičić and M. Spasić

Stimulated erythropoiesis and reticulocytosis can be induced by daily bleeding, or by phenylhydrazine (PHZ) treatment. We compared the in vivo effects of PHZ and bleeding treatment on haematological, energy and redox status parameters in red blood cells (RBC) of rats. The results showed that all followed haematological parameters were significantly lower in bleeding, compared to PHZ-treated rats. PHZ induced even 2.58-fold higher reticulocytosis as compared to bleeding treatment. Although PHZ induced higher reticulocytosis, respiration intensity and energy production was lower than in bleeding-induced reticulocytes. These alterations were the consequence of increased superoxide anion and peroxynitrite concentrations in PHZ-treated rats. Bleeding treatment resulted in increased activity of an antioxidative enzyme, superoxide dismutase. In conclusion, differences in these two experimental models for reticulocytosis may be used as tools for appropriate pharmacological testing of redox-active substances considering energy and redox processes, as well as apoptosis pathways.

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