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A modified method for the analysis of nicosulfuron, rimsulfuron and prosulfuron was developed and validated by using microwave-assisted extraction (MAE) and ultra-performance liquid chromatography with diode array detection in the ultraviolet region (HPLC-UV-DAD). The most important experimental parameters of extraction procedure and HPLC-UV-DAD technique were optimised in respect to those sulfonylurea herbicides. High recoveries of the microwave-assisted extraction were obtained by using a dichloromethane–acetonitrile mixture (2:1 volume ratio) acidified with acetic acid (0.8 vol.%) with the addition of urea. The mean recoveries at three spiking levels ranged from 97.47 to 98.76% for nicosulfuron, 97.88 to 99.17% for rimsulfuron and from 97.91 to 99.83% for prosulfuron. The limits of detection of nicosulfuron, rimsulfuron and prosulfuron were 0.95, 0.91 and 0.89 μg kg–1, respectively. The accuracy of the developed method was confirmed by HPLC coupled with tandem mass spectrometry parallel analyses. The developed method was used to investigate the dissipation dynamics of sulfonylurea herbicides in the real field trials in Vojvodina Province, Serbia. The obtained half-lives were 0.05, 0.23 and 0.15 days for recommended dose application of nicosulfuron, rimsulfuron and prosulfuron, respectively. Low residues and short half-life in soil suggested that the risk to sensitive rotational crops after application of those sulfonylurea herbicides is low when they are used in the appropriate dosages. [Project of the Serbian Ministry of Education, Science and Technological Development, Grant no. TR 31072]

The study deals with mineral characterization of natural waters from South-East Serbia. The contents of aluminium, arsenic, calcium, cadmium, cobalt, chromium, cooper, iron, potassium, magnesium, manganese, sodium, nickel, lead and zinc were analysed in spring, ground and river waters by inductively coupled plasma-atomic emission spectrometry (ICP-AES) technique. The study area was in the Southern Serbia, and included slopes of Rtanj, Ozren, Bukovik, Vrdenik and Čemernik mountains, and the valley of South Morava. Obtained contents were compared with Serbian regulations on the quality of water for human use, and directive of World Health Organization (WHO) for maximum allowed concentrations of chemical substances. High contents of macro-elements, namely calcium, magnesium and potassium, were detected in several spring and ground water samples which are believed to be due to direct influence of rock minerals. Some water samples contained iron, manganese and copper in concentration up to 84.2 μg dm-3, 8.10 μg dm-3 and 14.9 μg dm-3, respectively, but within the permissible limits. Other heavy metals were not detected in analysed samples. Based on the derived results, tested ground and spring water samples have significant potential to be used as sources for the production of bottled water, but further investigations are necessary. Additional investigations have to be focused on complete physical, chemical and microbiological assessments of water resources. Systematic hydrogeological assessment also should be performed in all seasons. In the meantime, precautionary measures should be immediately taken to protect and preserve these water resources. [Projekat Ministarstva nauke Republike Srbije, br. TR 31014]

The quality of goat meat has recently become an important aspect in the marketing of goats in Serbia. The aim of this study was to compare some goat meat quality parameters of various races and to determine the differences between them. Goat breeds were Balkan goat and Serbian White goat, both female in the age of four years. Analysis of quality parameters: chemical composition (moisture, protein, total fat, ash,), pH value, fatty acids, amino acids, microelements content, tenderness, cooking loss and colour measurements were done. Statistically significant difference was found between the samples of two groups of goat meat (P

On the basis of the generalized photoacoustic response model, which includes the influence of thermal memory on both thermoconducting and thermoelastic components, photoacoustic response of thin films is analyzed. It is demonstrated that the influence of thermal memory is manifested at frequencies above certain boundary frequency, which depends on thermal memory properties of the sample and its depth. A linear relation, linking heat propagation velocity and measured signal, is derived. Taking into account the confinement of the frequency range imposed by the measuring system, it is indicated that thermal memory properties of non-cristaline thin films can be determined in a photoacoustic experiment.

Chemical composition, pH value, fatty acids profile, cholesterol content, color and sensory analysis of pork meat from Duroc x Yorkshire (D x Y), Duroc x Yorkshire x wild boar (D x Y x WB) crossbreeds and wild boars (WB) was investigated. Samples for all tests were taken from m. longissimus dorsi. Chemical composition and pH value were tested by ISO methods. Fatty acid and cholesterol determination was performed by gas chromatography technique with external standard method. Color was determined instrumentally using the thristimulus colourimeter. The overall sensoric quality (appearance, texture and smell) of samples of raw meat was evaluated. In evaluation of results the scoring system was used. In chemical composition (moisture, fat, protein, ash) and pH values statistically significant difference was noted (p

The rheological properties of corn and potato starch concentrated aqueous solutions were investigated at 25ºC. The starches were previously dispersed in water and the solutions were obtained by heating of dispersions at 115-120ºC for 20 minutes. The solutions of potato starch were transparent, while the corn starch solutions were opalescent. The results of dynamic mechanical measurements showed that the values of viscosity, h, storage modulus, G′, and loss modulus, G″, of the corn starch solutions increased with the storage time. This phenomenon was not observed for the potato starch solutions. It was assumed that the increase of h, G′ and G″ is the result of starch solutions retrogradation. The potato starch solutions retrogradation did not occur probably because of the phosphates presence. The viscosity of 2 mass % corn starch solution is less than the viscosity of 2 mass % potato starch solution. By increasing the concentration of corn starch solution the gel with elastic behavior was formed. The corn starch solutions formed gel as early as at 4 mass % concentration, while potato starch solutions achieved the gel state at the concentration of 5 mass %. The value of exponent m (G′ and G″ µ wm) during the transition of potato starch solutions to gel is 0.414, which gives the fractal dimensions for corn starch of 2.10. The obtained value of fractal dimension corresponds to slow aggregation. The corn starch solutions with the starch concentrations higher than 4 mass % form weak gels. For these solutions the values of modulus in rubber plateau were determined. It was found that the modulus in rubber plateau increased with the concentration by the exponent of 4.36. Such high exponent value was obtained in the case when the tridimensional network is formed, i.e. when supermolecular structures like associates or crystal domains are formed.

An experimental study was carried out with the aim of evaluating the quality of the lipid fraction of Serbian biscuits. Total fat contents of the biscuit samples ranged between 10.2% and 24.5%. The saturated, cis-monounsaturated and cis-polyunsaturated fatty acid contents were within the ranges of 18.585.6%, 10.649.9% and 2.713.3% of total fatty acids, respectively. The content of trans fatty acids (TFA) ranged from 0.0% to 42.5% and the mean was 10.2%. In a total of 34 investigated samples, 10 of them were found to be trans - free, 8 contained low level of TFA (under 2%), 4 samples contained between 2 and 10% of TFA, while 12 samples contained very high amounts of TFA (12.042.5%). The results obtained showed a considerable variability in fatty acid composition of biscuits which indicated that different types of fats and oils were used for production of biscuits in Serbia.

The subject of the study was investigation of influence of substituent type on the properties of starch derivates in diluted solutions. Three samples were prepared: two anionic (carboxymethyl starch, CMS) and one cationic starch (KS). Starch derivates were synthesized in two steps. The first step was preparation of alkali starch by the addition of sodium-hydroxide to the starch dispersed in ethanol or water. In the second step, the required amount of sodium monocloracetate or 3-chloro-2-hydroxypropyl-threemethylamonium chloride was added to the obtained alkali starch in order to prepare CMS or KS, respectively. The degree of substitution of carboxymethyl starch was determined by back titration method, and the degree of substitution of cationic starch was determined by potentiometric titration. The degrees of substitution of prepared samples were: 0.50 (assigned as CMS-0.50) and 0.70 (assigned as CMS-0.70) for carboxymethyl starch and 0.30 (assigned as KS-0.30) for cationic starch. The properties of starch derivatives in dilute solutions were investigated by the methods of static and dynamic light scattering. Aqueous solutions of sodium chloride of different concentrations were used as solvent. The values of the mass average molar mass, MW, radius of gyration, Rg, and second virial coefficient, A2, were determined for all samples together with hydrodynamic radius, Rh. Molar masses of the samples were: 5.06×106, 15.4×106 and 19.2×106 g/mol for CMS-0.50, CMS-0.70 and KS-0.30, respectively. The samples, CMS-0.70 and KS-0.30 had similar molar mass and hydrodynamic radius, but radius of gyration of KS-0.30 was smaller then radius of gyration of CMS-0.70 at all sodium chloride concentrations. Consequently, ρ value for KS-0.30 was smaller then for CMS-0.70, as a result of more compact architecture of KS-0.30 then of CMS-0.70. Kratky graph confirmed this result. For all samples, radius of gyration and hydrodynamic radius decreased with increasing of sodium chloride concentration, but decrease of the radius was greater for CMS-0.50 then for other two samples due to its significantly lower molar mass. On the other hand, change of both radius of gyration and hydrodynamic radius of CMS-0.70 and of KS-0.30 with increasing sodium chloride concentration were similar. It can be concluded that the decrease of both Rg and Rh with increasing sodium chloride concentration in water depends far more on molar mass than on degree of substitution.

Carboxymethyl starch samples were prepared by etherification in heterogeneous media. Three samples were prepared from corn starch and three samples from potato starch. Degree of substitution of prepared samples ranged from 0.40 to 1.10. The samples were investigated by static and dynamic light scattering and viscosity of diluted solution in 0.10 M NaCl as solvent at 25 C. The values of molar mass, MW, radius of gyration, Rg, hydrodynamic radius, Rh, and limited viscosity number, [η] were determined. It was found that the samples are similar to each other regardless of the type of starch and the degree of substitution. Fractal dimension, df, was equal to 2.380 (Rg - MW) and 2.406 (Rη - MW), while parameter was 1.195. The values of fractal dimension and parameter are characteristic values for the behavior of branched clusters in thermodynamically good solvents.

An analytical model that describes surface temperature variations of media with thermal memory stimulated by laser pulses was developed. The influence of thermal memory for semi infinite sample was analyzed by comparing our results with classical model results which neglect the thermal memory of materials for different pulse widths and for different pulse shapes. It was shown that this influence was outstanding around steep changes of the incentive flux and for short incident pulses.

Carboxymethyl starch was synthesized by the esterification of starch with monochloroacetic acid in ethanol as a reaction medium. Three samples of carboxymethyl starch having different degrees of substitution were prepared. The influence of temperature on the viscosity of concentrated carboxymethyl starch solutions, as well as the dynamic-mechanical properties of the concentrated solutions were investigated. The activation energy of viscous flow was determined and it was found that it decreased with increasing degree of substitution. The results of the dynamic-mechanical measurements showed that solutions of starch and carboxymethyl starches with higher degrees of substitution behave as gels. Values of the storage modulus in the rubbery plateau were used to calculate the molar masses between two points of physical crosslinking, the density of crosslinking and the distance between two points of crosslinking.

Hydroxyapatite/poly-L-lactide (HAp/PLL) composite biomaterial can be obtained by different processing methods. Three-dimensional blocks of HAp/PLLA composite biomaterial with mechanical characteristics close to the natural bone tissue can be obtained by hot pressing procedure. Effects of synthesis and compacting on the structure and characteristics of the HAp/PLLA composite biomaterial were studied in this work. Using wade angle X-ray structural analyses (WAXS), differentially scanning calorimetry (DSC), thermogravimetric analysis (TGA) and infrared (IR) spectroscopy, the changes occurring in the material during synthesis and hot pressing were monitored. Surface microstructure was analyzed by scanning electronic microscopy (SEM) coupled with electron-dispersion analysis (EDX). The results obtained indicate a possible decrease in the degree of crystallinity with hot pressing time increase. A block of HAp/PLLA composite biomaterial with 1.6 times lower crystallinity of the polymer phase was obtained by hot pressing in a given time interval with a maximum of 60 minutes. Results of TG analysis show that PLLA stability decreases with increasing hot pressing time, and vice versa. IR study proved that neither destructive changes in constituents nor formation of new phases occurred during hot pressing.

The basic raw materials for the chemical industry, which also means for polymer production, are mineral oil and natural gas. Mineral oil and natural gas resources are limited so that sooner or later they will be consumed. For this reason alternative, renewable raw materials for the chemical industry have become the object of intensive investigation all over the world. Some of the results of these investigations concerning renewable raw materials for the production of polymer materials are presented in this paper.