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Sage herbal dust generated as a by-product from filter-tea factory contains various bioactive compounds which secured its economic potential towards valorization of under-utilized stream. The aim of this work was to utilize sage herbal dust as raw material for the recovery of value-added product. Comparative evaluation of hydrodistillation (HD) and microwave-assisted hydrodistillation (MWHD) processes applied for isolation of sage herbal dust essential oil (EO) were applied for this purpose and EO yield varied from 0.50 to 1.90%. Distillation experiments performed at different levels of power and kinetics of EO recovery were monitored, while four empirical kinetic equations were successfully applied for modeling of process kinetics according to appropriate values of statistical parameters (R2 and AARD). GC-MS analysis was applied for chemical characterization of sage EOs, while DPPH assay was used to determine in vitro bioactivity and results suggested that power affected terpenoid profile and antioxidant activity in case of HD and MWHD. Thermal analysis of obtained EOs was utilized to establish correlation between thermal behavior and terpenoids profile. Results suggested that MWHD could provide excellent alternative for production of high-quality sage EO with high content of oxygenated terpenoids and adequate bioactivity.

The essence of this study is synthesis of a newly developed and efficient heterogeneous catalyst based on aluminum oxide support promoted with potassium iodide (KI) as active dopant responsible for pronounced catalyst activity. Modified sol–gel, reflux and hydrothermal method were used for synthesis of aluminum-oxide support using aluminum isopropoxide as a precursor. The γ-Al2O3 support and KI/γ-Al2O3 catalyst samples were examined by various experimental techniques. Effects of several operational parameters were considered and those are: methanol to sunflower oil molar ratio, catalyst loadings, reaction time and reaction stirring rate. The obtained results indicated that modified sol–gel method for synthesis of γ-Al2O3 catalyst support is the most favorable for obtaining the catalyst with superior catalytic performances in transesterification of sunflower oil. A maximum conversion (triglycerides to methyl esters) of 99.99% was achieved using the SG-KI/γ-Al2O3-770 catalyst under following optimal process parameters: 15:1 methanol to sunflower oil molar ratio, 2.5 wt% catalysts loading, 600 rpm stirring rate and 4 h of the reaction run. Link to erratum: [https://vinar.vin.bg.ac.rs/handle/123456789/10192]

The micellization behavior and foamability of a mixture of anionic surfactant sodium laureth sulfate (SLES) and nonionic polysorbate surfactants commercially available as Tween series were investigated. The mole fraction and the structure of the hydrophobic part of various polysorbates affect the critical micellar concentration (CMC) and foam height and stability of anionic surfactant. Experimental values of CMC were determined by measuring specific conductivity at 25°C and foam height and stability by modified Ross–Miles method at 23°C. The negative deviation of the experimentally determined CMC from theoretical values for ideal mixed micelle indicate non-ideal mixing behavior due to synergism as a consequence of attractive interactions between the individual surfactants in formed micelles. Thus synergism increase with increasing of both the mole fraction and length of hydrophobic tail of examined Tween in SLES/Tween mixtures. Foam height and stability significantly decrease with increasing length of the hydrophobic tail of Tween surfactants and their mole fractions in the binary mixture.

In this study, influence of the extraction techniques on the quality of the sage essential oil was investigated. Obtained samples were analyzed for chemical composition by GC/MS, thermal properties by thermogravimetric analysis (TGA), and for biological activity: antioxidant (DPPH, CUPRAC, FRAP, ABTS, HRSA and TBARS), microbiological (

Stinging nettle is annual plant from Urticaceae family used as food and medicine. Due to the nonsufficient data, this work aimed to isolate the bioactive compounds from the stinging nettle leaves by supercritical carbon dioxide. Extracts were analyzed and assessed for antioxidant and cytotoxic activities. Main fatty acids were α-linolenic (31.06-58.42 mg/g E), palmitic (9.17-13.12 mg/g E), and linoleic (10.93-16.51 mg/g E) acids. Chlorophylls (33.00-7365.11 mg/100 g E) and carotenoids (166.88-722.62 mg/100 g E) were also found in all samples. Four empirical kinetic equations were effectively utilized for kinetic modeling of supercritical fluid extraction. As per proper statistical features, empirical models show good concurrence with experimental data. The numerical modeling of a process is gainful to foresee the process conduct and furthermore extend the methodology from laboratory to industrial scales. The principal component analysis was used to visualize the fatty acids profile, antioxidant capacity, and cytotoxic activity of extract.

Stinging nettle (Urtica dioica L.) is annual plant from Urticaceae family growing wild all over the world. Throughout the history, this plant found its place as a both food and medicine. Due to the nonsufficient study, this work aimed to isolate the bioactive compounds from the stinging nettle leaves by supercritical fluid extraction. Extracts were analyzed and assessed for antioxidant and cytotoxic activities. Main fatty acids were α-linolenic, palmitic, and linoleic acids in all six samples. Beside fatty acids, chlorophylls and carotenoids were also found in all samples. Four empirical kinetic equations were effectively utilized for kinetic modeling of supercritical fluid extraction of stinging nettle leaves oil. As per proper statistical features, empirical models show good concurrence with experimental data. The numerical modeling of a process is gainful to foresee the process conduct and furthermore extend the methodology from laboratory to industrial scales. The principal component analysis was used to visualize the fatty acids profile and antioxidant capacity and cytotoxic activity of extract obtained from stinging nettle leaves. It was found that both composition and activity were strongly dependent on the parameters of the extraction process.

When edible oils are heated above 150°C, they undergo thermo-oxidative changes depending on a variety of factors, such as temperature, heating time, type of oil, etc. These changes cause a series of chemical reactions (hydrolysis, oxidation, polymerization, etc.) resulting in the formation of free fatty acids, an increase in the peroxide number and the acid number, a change of color and a decrease in the iodine number. This study investigates changes of the content of free fatty acids, the acid number, and the peroxide number in edible sunflower oil when heating at the temperature range from 110°C to 190°C for 30 minutes, as well as after the adsorption by a natural and a synthetic adsorbent (clinoptilolite and zeolite 4A). The results of the research show that these adsorbents are effective in removing the products of chemical reactions occurring in thermal degradation, which is particularly evident after the adsorption of oil heated at 190°C. Somewhat better results were achieved after the adsorption using clinoptilolite, with a 72 % reduction in the content of free fatty acids, 83 % reduction in the acid number, and 43 % reduction in the peroxide number. After the adsorption by zeolite 4A, the content of free fatty acids was reduced by 65%, the acid number by 76 %, and the peroxide number by 39 %. The results obtained open the possibilities of further research aiming at discovering the adsorbents which would be most suitable for the regeneration of used edible oils, after which they could be applied safely for different purposes. Keywords: edible oil, free fatty acids, acid number, peroxide number, adsorbent

The aim of this study was to provide information on the phenolic and sugar profiles of different parts of the buckwheat plant, which can define that buckwheat is a functional food, with a high nutritional value and very useful for human health. Therefore, the extracts of buckwheat leaf, stem, and flower, as well as buckwheat grain were analysed for the content of polyphenol and antioxidant tests. The identification of a notable number of phenolic compounds and quantification of sugars in different parts of buckwheat indicates that buckwheat is a highly valuable plant. A total of 60 phenolic compounds were identified (18 cinnamic acid derivatives, 14 flavonols, 13 flavan-3-ols (including proanthocyanidins), 10 hydroxybenzoic acid derivatives, and 5 flavones) using ultra-high-performance liquid chromatography (UHPLC), coupled with a hybrid mass spectrometer which combines the Linear Trap Quadrupole (LTQ) and OrbiTrap mass analyzer. The highest number of phenolic compounds was found in the analysed buckwheat flower sample, and then in the leaf, followed by the grain and the stem. In addition, the sugar profile of buckwheat leaf, stem, flower and grain, as well as the buckwheat pollen and the nectar was analysed. Hence, 16 sugars and 5 sugar alcohols were detected by the high-performance anion exchange chromatography (HPAEC) with a pulsed amperometric detector (PAD). Sucrose was found in a significant amount with the highest content in buckwheat leaf. Trisaccharides had similar accumulation in the sample extracts, while disaccharides dominated in buckwheat leaf, followed by nectar and pollen. The sugar alcohols showed the highest content in buckwheat grain, where erythritol was predominant. The obtained results show that buckwheat is very rich in phenolic compounds and sugars. In addition to grain, the other parts of the buckwheat plant can be used as a very good source of different classes of phenolic compounds. This study provides useful information on the distribution of phytochemicals in different parts of the buckwheat plant, which contribute to the maintaining of the status of buckwheat as a functional food. Supplementary material: [https://cherry.chem.bg.ac.rs/handle/123456789/4740]

Six ethanolic extracts, obtained from anise, fennel, lavender, sage, mint, white horehound and their mixture were directly applied onto cellulose (viscose) fabric to impart antimicrobial and antioxidant functionality for its potential use as a wound dressing. Antimicrobial activity of treated fabrics against gram-positive bacteria S. aureus and yeast C. albicans, as common skin pathogens, was determined by agar diffusion test. The most effective against both microorganisms was viscose with anise, fennel, and mint, whereby clear inhibition and suppression zones were detected. The oxidation of viscose, intended to improve sorption properties and consequently adsorption of extracts, increased the antimicrobial activity of viscose with a mixture of extracts. The antioxidant activity of fabric samples with extracts, determined by 2,2-Diphenyl-1-picrylhydrazyl (DPPH) assay, was significantly higher when compared to the untreated viscose sample (2.38 %) and ranged from 11.82 % for viscose with fennel up to 87.71 % for viscose with sage. Oxidation of fabric before sorption of extracts mixture contributes to higher antioxidant activity (68.81 %). Direct impregnation of bioactive plants extracts onto the fabric represents low cost and simple method, which makes it suitable for obtaining eco-friendly, low-cost disposable medical textiles with the therapeutic and prophylactic role.

In the last decades, human and industrial activities in the coastal areas have increased and that resulted in different types of contamination, including trace elements. Therefore, investigations of the southeastern Adriatic marine environment quality are intensified following seawater, biota, and sediment quality related to metals pollution. Since standard chemical analysis methods cannot provide accurate information about concentrations of trace elements in seawater, the seagrass Posidoniaoceanica (L.) Delile and the mussel Mytilusgalloprovincialis Lamarck, 1819, were used as water pollution bioindicators for identifying, especially, toxic trace elements in the Mediterranean. Surface sediment, seawater, seagrass (P. oceanica), and mussel (M. galloprovincialis) samples were collected in different seasons from the coastal area of Boka Kotorska Bay in the last 10 years (2006–2016), and analyzed in order to determine the seawater quality mainly related to Fe, Mn, Zn, Ni, Cu, Co, Cd, As, Pb, and Hg. Based on the analysis of the metal pollution index values (MPIs) in both species the highest metal concentrations were measured in winters for most of the studied trace elements. The Hg accumulation in both investigated organisms was the lowest and almost the same.

A focus of research in recent years is the comparison of honey as the final product of bees with pollen and nectar of the plant from which the honey originates, as the main food source for bees. Buckwheat honey is recognized as a nutritionally valuable product, which provides a scientifically proven health benefit and is confirmed as a functional food. The quality of this type of honey is attributed to high levels of phytochemicals in buckwheat. The purpose of this study was the examination of similarity between buckwheat honey and buckwheat nectar and pollen, as well as simultaneous investigation of their chemical profiles and the origin of the honey. The phenolic profile of buckwheat pollen showed a lower number of flavonoids and phenolic acids than those of nectar and honey samples, but confirmed the presence of the most characteristic polyphenols derived from the buckwheat plant. The notable difference was found to be the presence of (epi)catechin units, its galloylated derivatives and procyanidin dimers, which were not present in honey. Honey polyphenols displayed a pronounced correlation with those of nectar, but not with those of pollen. Finally, by comparing the polyphenolic profiles of honey, nectar and pollen sharing the same geographical origin, new data could be provided for a potential assessment of the botanical origin of buckwheat honey.

Rosemary (Rosmarinus officinalis L.) is a plant worldwide cultivated mainly for essential oils, extracts, and as a spice. Up-to-date results showed diversity in composition of the essential oils, which may influence their quality, biological activity, and thermal properties. Therefore, the aim of this study was to investigate the chemical composition, antimicrobial activity, and thermal properties of the rosemary essential oils originating from Serbia and Russia. Additionally, oils were added to the sunflower oils in order to investigate possible antioxidant activity during the frying. Investigation of the chemical profile marked α-pinene, eucalyptol, and camphor as the most abundant compounds in both oils. However, overall composition influenced in such manner that Russian oil showed significantly higher antimicrobial activity, while Serbian oil proved to be better antioxidant agent in case of frying of sunflower oil. This would significantly influence possible application of the oils, which could be used as an antioxidant agent for extension of the food shelf life, or antimicrobial agent for protection against different microbial strains. Supplementary material: [https://cherry.chem.bg.ac.rs/handle/123456789/4793]

The aim of this study is to investigate the multi-day behavior of the electromotive force (EMF) between Pt and reference Ag/AgCl, KClsat. electrodes immersed in various aqueous systems (deionized water, 1 × 10−3 M H2SO4 solution and 0.15 M KCl solution) at 32 °C and also at ambient temperature, without oxygen removal and redox species introduction. The control test of EMF behavior in the presence of redox species was performed with cyanide complexes of Fe2+ and Fe3+ ions at ambient temperature. In experiments with deionized water, systems were protected against the influence of daylight and static electricity. The results have shown diurnal oscillations of EMF in all investigated systems with amplitudes in the range ≈ 1 to 25 mV depending on applied experimental conditions. EMF oscillations in deionized water were independent on the applied temperature and yielded amplitudes of 15–25 mV in daylight regime, and only a few mV when protected from its influence. The effect of electrostatic electricity was not observed. Diurnal EMF oscillations with the amplitudes ≤ 5 mV were observed individually in 0.15 M KCl solution, redox system and after 4 days of investigation in H2SO4 solution. Results presented in this work pointed out that the behavior of Pt–oxygen electrode is specific and very complex, even in the simplest system such as deionized water. To investigate the origin of the observed EMF oscillations and the application of Pt–oxygen electrode in in situ multi-day dynamics studies under open-circuit potential condition, additional theoretical and experimental methods and particularly electrochemical ones, must be applied.

The physicochemical properties of initial formulation, that is anionic/amphoteric surfactants mixture SLES/AOS/CAB (sodium lauryl ether sulfate (SLES), alpha-olefin sulfonates (AOS) and cocamidopropyl betaine (CAB) at ratio 80 : 15 : 5) with nonionic surfactant of amine oxide type (lauramine oxide (AO)) in various concentration (1-5%) were studied. To characterize the surfactants mixture, the critical micelle concentration (CMC), surface tension (gamma), foam volume, biodegradability and irritability were determined. This study showed that adding of AO in those mixtures lowered both gamma and CMC as well as enhanced SLES/AOS/CAB foaming properties, but did not significantly affect biodegradability and irritability of initial formulation. Moreover, an increase in AO concentration has a meaningful synergistic effect on the initial formulation properties. All those results indicates that a nonionic surfactant of amine oxide type significantly improves the performance of anionic/amphoteric mixed micelle systems, and because of that anionic/amphoteric/nonionic mixture can be used in considerably lower concentrations as a cleaning formulation.

The present work describes application of natural triglycerides for lipase-catalyzed esterification of structurally diverse flavonoids-esculin, naringin, and phloridzin. Ester mixtures with laurate, linolenate, or linoleate as prevailing products were obtained in reactions with coconut, linseed, and sunflower oils, respectively. By using response surface methodology, the influences of key experimental factors-reaction time, substrates, and enzyme concentrations-for transesterification of esculin with linseed oil were investigated. High molar conversion (78.5%), product yield (19.13 mg/mL), and specific yield (2.83 mmol/g(enzyme)) were achieved at optimized conditions. Determined optimums were successfully applied in esculin transesterification with other two oils. Furthermore, esculin ester mixtures were incorporated in gel emulsions, and their effect on transepidermal water loss (TEWL) as well as skin sensitivity was examined. Obtained results have shown significant hydration effect and good dermatological compatibility without irritating effects of all examined preparations containing oil-derived esculin esters, making them very prospective for application in skin care products.

Rhamnolipids are biodegradable low toxic biosurfactants which exert antimicrobial and anti-biofilm properties. They have attracted much attention recently due to potential applications in areas of bioremediation, therapeutics, cosmetics and agriculture, however, the full potential of these versatile molecules is yet to be explored. Based on the facts that many naturally occurring lipopeptides are potent antimicrobials, our study aimed to explore the potential of replacing rhamnose in rhamnolipids with amino acids thus creating lipopeptides that would mimic or enhance properties of the parent molecule. This would allow not only for more economical and greener production but also, due to the availability of structurally different amino acids, facile manipulation of physico-chemical and biological properties. Our synthetic efforts produced a library of 43 lipopeptides revealing biologically more potent molecules. The structural changes significantly increased, in particular, anti-biofilm properties against Candida albicans, although surface activity of the parent molecule was almost completely abolished. Our findings show that the most active compounds are leucine derivatives of 3-hydroxy acids containing benzylic ester functionality. The SAR study demonstrated a further increase in activity with aliphatic chain elongation. The most promising lipopeptides 15, 23 and 36 at 12.5 µg/mL concentration allowed only 14.3%, 5.1% and 11.2% of biofilm formation, respectively after 24 h. These compounds inhibit biofilm formation by preventing adhesion of C. albicans to abiotic and biotic surfaces.

The return maps, as an element of mathematical phenomenology appropriate for general examinations of complex dynamic states of the oscillatory systems were used to detect and explain the evolution of mixed-mode oscillations and chaos in a six-dimensional nonlinear reaction system of the Bray-Liebhafsky (BL) reaction, a well-studied nonlinear chemical reaction system that exhibits complex dynamic behavior. For this purpose principally different Poincar, sections were applied and different transition scenarios between periodic and aperiodic states were examined by numerical simulations. It is shown that emergence of new periodic patterns can be detected by return maps already within chaotic windows. Besides, we also show that the higher dimensionality of manifold gives the impression of having several layers of manifolds.

The main goal of this study was to establish the chemical profile of Osage orange (Maclura pomifera) leaf extracts, obtained by conventional maceration technique, and to examine its antimicrobial activity. The identification and quantification of the extract compounds were done using ultra-high-performance liquid chromatography, with a diode array detector coupled with triple-quadrupole mass spectrometer and gas chromatography-mass spectrometry techniques. Thirty-one polyphenolic compounds were detected and identified in the ethanolic extracts, whereby 5-O-caffeoylquinic acid was found to be the dominant compound. Among other compounds, pentacosane and palmitic acid were the most abundant compounds in the dichloromethane extract. The preliminary antimicrobial activity screening shows that Gram-positive bacteria tend to be more sensitive to the investigated extracts. The highest antimicrobial activity was determined against Enterococcus faecalis ATCC 19433 and Listeria monocytogenes ATCC 35152. From these results, Osage orange leaves can be considered as plant material with significant antimicrobial properties.

Laurus nobilis (bay laurel) form Serbia (SRBL) and Russia (RFBL) were analyzed in order to establish the chemical profile, thermal properties and biological activity. The GC/MS analysis showed that α-pinene (31.97%) is principal compound in the RFBL followed by eucalyptol (27.95%) and α-terpineol (10.28%). In the case of the SRBL, eucalyptol (40.51%) is the most abundant compound followed by α-terpineol (15.46%), while α-pinene was found in much lower amount (4.45%). Thermal analysis showed that the evaporation process of both oils was complex process and took place in two phases. Moreover, results indicated that the SRBL evaporated slower at the higher temperatures than the RFBL. In order to assess biological activity, the antioxidant and antimicrobial activities were investigated. The SRBL was more potent antioxidant agent in the case of both assays (DPPH and total reduction capacity). In the case of the antimicrobial activity, the SRBL showed greater potential of antimicrobial activities toward all tested microorganisms, while RFBL was found to be effective against all the bacteria and yeast, but did not possess any inhibitory action against fungi. Results indicate that both oils may be used in the food and pharmaceutical industries as antioxidant and antimicrobial agent.

Everyday food preparation often involves cooking on vegetable oil, where heating at temperatures over 110 °C changes the quality of oil due to various chemical reactions. In this paper, the degree of thermal degradation of edible oil was investigated when heating oil at a temperature ranging from 110 to 190 °C for 10 and 30 min. The reference to the quality of edible oil is the content of free fatty acids (FFA) which increases as the temperature rises, due to hydrolysis.

The system KSCN-H2O2-CuSO4-NaOH, also known as the OrbA n-Epstein oscillatory reaction, is exposed to external perturbations by several phenolic compounds: catechol, resorcinol, hydroquinone, 2,5-dihydroxybenzoic acid, 2,6-dihydroxybenzoic acid, 2,3-dihydroxybenzoic acid, 2,4-dihydroxybenzoic acid, 3,4-dihydroxybenzoic acid, 3,5-dihydroxybenzoic acid, caffeic acid, and ferulic acid. As a result of the performed perturbation in most examined cases, oscillations have been inhibited for some characteristic time, and resumed afterwards. The evaluated inhibition time is typical for each substance and strongly dependent on its concentration. The chemical mechanism of the interaction between the OrbA n-Epstein system and phenolic compounds is briefly discussed. Numerical simulations are performed using the original OrbA n-Epstein model with 30 reactions, extended by three reactions describing the interaction with inhibitory substances. The rate constants of three added reactions are adjusted to fit experimental inhibition times, and compared among used compounds. The observed effects are discussed further in relation with the bond dissociation enthalpy theory. Unlike other tested compounds, 2,5-dihydroxybenzoic acid remains off from predicted order of activity.

Essential oils (EOs) are aromatic oily liquids prepared from plant material. Many plants are rich in EOs, which usually consisted of different secondary metabolites such as terpenoids. The EOs or their components have been shown to exhibit antioxidant, antimicrobial, antiviral, antimycotic, antitoxigenic, antiparasitic and insecticidal properties, which is main reason for their ivenstigation. Coriander and sage essential oils, isolated by hydrodistillation, were analyzed using gas chromatography, differential scanning calorimetry and thermogravimetry techniques in order to correlate chemical composition and thermal behavior. Results showed that evaporation process of sage EO takes place in two steps, while coriander EO was evaporated in one step. The activation energy of the evaporation process of both EOs was in accordance to the evaporation enthalpy of dominant compounds in analyzed samples. The quantitative structure–retention relationship (QSRR) was employed to predict the retention time (RT) of essential oil compounds obtained by GC analysis, using five molecular descriptors selected by genetic algorithm. The selected descriptors were used as inputs of an artificial neural network (ANN), to build an RT predictive QSRR model. The coefficient of determination was 0.969, indicating that this model could be used for prediction of RT values for coriander and sage essential oil compounds.

Performance and efficiency of anionic [sodium lauryl ether sulfate (SLES) and sodium alpha-olefin sulfonate (AOS)] and amphoteric [cocamidopropyl betaine (CAB)] as well as nonionic [cocodiethanol amide (DEA), various ethoxylated alcohols (C-12-C-15-7EO, C-10-7EO and C-9-C-11-7EO) and lauramine oxide (AO)] surfactants in various dishwashing liquid mixed micelle systems have been studied at different temperatures (17.0, 23.0 and 42.0 degrees C). The investigated parameters were critical micelle concentration (CMC), surface tension (gamma), cleaning performance and, foaming, biodegradability and irritability of anionic (SLES/AOS) and anionic/amphoteric/nonionic (SLES/AOS/CAB/AO) as well as anionic/nonionic (SLES/AOS/DEA/AO, SLES/AOS/C-12-C-15-7EO/AO, SLES/AOS/C-10-7EO/AO and SLES/AOS/C-9-C-11-7EO/AO) dishwashing surfactant mixtures. In comparison to the starting binary SLES/AOS surfactant mixture, addition of various nonionic surfactants promoted CMC and gamma lowering, enhanced cleaning performance and foaming, but did not significantly affect biodegradability and irritability of dishwashing formulations. The anionic/nonionic formulation SLES/AOS/C-9-C-11-7EO/AO shows both the lowest CMC and gamma as well as the best cleaning performance, compared to the other examined dishwashing formulations. However, the results in this study reveal that synergistic behavior of anionic/nonionic SLES/AOS/ethoxylated alcohols/AO formulations significantly improves dishwashing performance and efficiency at both low and regular dishwashing temperatures (17.0 and 42.0 degrees C) and lead to better application properties.

By numerically simulated Bray-Liebhafsky (BL) reaction under a continuously fed well stirred tank reactor (CSTR) conditions, we discussed the attractors and Poincar, 1D maps with respect to flow rate as the control parameter. The new technique of the return maps from transient trajectories over the slow manifold is developed and applied in order to explore its multilayered structure related to dynamical states (periodic and aperiodic -chaotic oscillating modes) of the system. Kinetic relations underlying the slow manifold structure are briefly discussed.

The hydrogen diffusion coefficient in an LmNi 3.55 Co 0.75 Mn 0.4 Al 0.3 alloy electrode was evaluated by potential-step method as a function of initial hydrogen concentrations in the bulk of alloy electrode ( C H C H at all temperatures. However, the slope of this linear dependence was found to reduce with the increasing temperature. The partial interaction Gibbs energy of dissolved hydrogen ( Δ G ¯ int ) revealed a strong influence of temperature on the stability of α-solid solution phase in the alloy electrode. Namely, the Δ G ¯ int gradually increased −25.6 to −2.5 kJ mol −1 with increasing temperature, showing a linear dependence. It is found that the Einstein diffusion coefficient of hydrogen increased also with increasing temperature, and that the apparent energy of activation of hydrogen diffusion is 27.9 kJ mol −1 . A novel viewpoint in understanding of the hydrogen diffusion kinetic in hydrogen storage alloys is discussed in view of the thermodynamic stability of the resulting hydrides.

Structural features of microemulsions such as the droplet radius, thickness of the surfactant layer at the interface, number and distribution of molecules within a droplet are calculated using LSCF field theory. The theory was also used to calculate the composition ratio, interfacial tension (γ) and bending moment (c) of spherical interfaces between oil and water. Presented results show that LFSCF approach can be used to predict microemulsion properties.

Modeling of any complex reaction system is a difficult task. If the system under examination can be in various oscillatory dynamic states, the apparent activation energies corresponding to different pathways may be of crucial importance for this purpose. In that case the activation energies can be determined by means of the main characteristics of an oscillatory process such as pre-oscillatory period, duration of the oscillatory period, the period from the beginning of the process to the end of the last oscillation, number of oscillations and others. All is illustrated on the Bray-Liebhafsky oscillatory reaction. Моделирање ма ког комплексног рекакционог система је тежак задатак. Ако испитивани систем може да постоји у различитим осцилаторним динамичким стањима, привидне енергије активације, које одговарају различитим реакционим путевима, могу бити од битне важности за моделирање. У том случају енергије активације могу бити одређене помоћу основних особина осцилаторног процеса као што су предосцилаторни период, трајање осцилаторног периода, период од почетка процеса до заршетка задње осцилације, број осцилација и других. Све ово је објашњено на Bray-Liebhfasky осцилаторној реакцији.

In order to evaluate the safety of selected commercial spices brands, concentration of lead, mercury and arsenic, as well as moisture and mineral contents were analyzed in samples of dried black and white pepper powders, black, white and green peppercorns, black cumin seeds and ginger powder. Lead (Pb), mercury (Hg) and arsenic (As) concentrations in spice samples purchased from local markets in Belgrade were determined, after a microwave digestion of the samples, by atomic absorption spectrometry (AAS), using the graphite furnace AAS technique (Pb), cold vapor AAS technique (Hg) and hydride generation AAS technique (As). Trace levels of Pb, Hg and As in the selected dried spices samples were in the range 0.10 ppm - 0.79 ppm, 0.01 ppm - 0.10 ppm and 0.01 ppm - 0.51 ppm, respectively. The maximum Pb concentration was determined in the sample of ginger and it was 0.79 ppm, the maximum concentration of Hg was 0.10 ppm, determined in green peppercorns samples, while the maximum concentration of As in powdered black pepper sample was 0.51 ppm. The moisture and mineral contents in the different analyzed spices were in the range 1.70-13.10% and 3.40-6.50%, respectively. According to the obtained results, the concentrations of the analyzed toxic elements, as well as the moisture and mineral content in selected spices, were below the maximum permissible limits declared by the national legislations deemed safe for human consumption. SADRŽAJ OLOVA, ŽIVE I ARSENA U ZACINIMA: CRNI, BELI I ZELENI BIBER, CRNI KIM I ĐUMBIR U ovom radu, u cilju utvrđivanja bezbednosti odabranih komercijalnih zacina, analizirane su koncentracije teskih metala, kao i sadržaj vlage i ukupnih mineralnih materija, u uzorcima susenog crnog i belog bibera u prahu, crnog, belog i zelenog bibera u zrnu, semena crnog kima i đumbira u prahu. Koncentracije olova (Pb), žive (Hg) i arsena (As) u uzorcima zacina iz lokalnih prodavnica u Beogradu, određene su nakon mikrotalasne digestije atomskom apsorcionom spektrometrijom (AAS), primenom tehnike grafitne peci (Pb), tehnike hladne pare (Hg) i hidridne tehnike (As). Određene koncentracije Pb, Hg i As u uzorcima susenih zacina su u opsegu 0,10 ppm - 0,79 ppm, 0,01 ppm - 0,10 ppm i 0,01 ppm - 0,51 ppm, redom. Maksimalna koncentracija Pb od 0,79 ppm određena je u uzorku đumbira, maksimalna koncentracija Hg od 0,10 ppm u uzorcima zelenog bibera u zrnu, dok je maksimalna koncentracija As određena u uzorku crnog bibera u prahu i iznosila je 0,51 ppm. U uzorcima ispitivanih zacina sadržaj vlage i mineralnih materija je u opsegu 1,70-13,10% i 3,40-6,50%, redom. Dobijeni rezultati pokazuju da su koncentracije ispitivanih teskih metala, kao i sadržaj vlage i mineralnih materija ispod maksimalno dozvoljenih vrednosti propisanih zakonskom regulativom Republike Srbije, kao i da su ispitivani uzorci crnog, belog i zelenog bibera u prahu i zrnu, crnog kima u zrnu i đumbira u prahu propisanog kvaliteta u ovom smislu. HIGHLIGHTS Commercially formulated anti-dandruff shampoos contain zinc pyrithione (ZPT) as an active ingredient that has antifungal, antibacterial and anti-seborrheic effects; In ZPT, pyrithione (PT) forms a complex with a zinc ion in the 2 : 1 ratio; Determination of ZPT concentration in commercial anti-dandruff shampoos by differential pulse polarography was based on an electrochemical reduction of zinc ions in ammoniacal buffer at pH 10.2; Surface active ingredients (anionic and amphoteric) and micro-components in the shampoos did not exert a polarographic interference for the determination of zinc and did not affect the determination of the content of ZPT active ingredient; This simple and sensitive differential pulse polarography method is suitable for a routine and rapid control of the active ingredient content, as well as for the quality control of anti-dandruff shampoos.

Some new experimental evidence of complex irregular oscillations in the Belousov-Zhabotinsky reaction realized in a batch reactor is presented. The results were obtained under relatively low cerium and malonic acid concentrations. One-dimensional maps were used for general discussion, and particularly, for the influence of noise on the evolution of the oscillations. Daju se novi eksperimentalni rezultati o kompleksnim neregularnim oscilacijama BŽ sistema ostvarenog u zatvorenom reaktoru, u uslovima relativno niske koncentracije cerijuma i malonske kiseline. Jednodimenzionalne mape su korišćene za generalnu diskusiju rezultata, a posebno za uticaj šuma na oscilatornu evoluciju.

Differential pulse (DP) and current sampled (TAST) polarography were applied for measuring hydrogen peroxide in actual washing systems. In addition to the possibility of the hydrogen peroxide determination in commercial detergent species containing sodium perborate monohydrate as bleaching substance, the change in peroxide concentration can be followed under the conditions which usually exist in the washing process. The possibility of determining dissolved oxygen in the peroxide decomposition reaction was also demonstrated.

Two basic glycoproteins homologous with thaumatin- and pathogen-related proteins of the PR-5 family were isolated from grain of brewers barley cultivar. The proteins inhibit fermentation and respiration of brewers yeast and exert a lethal effect on the yeast cells. In addition a significant release of cell constituents was registered. All these effects are dose dependent and tend to saturation at higher dosage. These results suggest that cell membrane damage causes the impairment of vital cell functions. Tracing these proteins in the course of the brewing process revealed that thermal treatment at the mashing stage of brewing leads to their disappearance due to denaturation.

By numerical calculations based on our previously proposed model with Br2O intermediate species we were able to simulate complex evolution of the Belousov-Zhabotinsky (BZ) reaction under batch conditions. In the defined region of initial malonic acid concentration [MA](0) (1.00 x 10(-3) mol dm(3) a parts per thousand currency sign [MA](0) a parts per thousand currency sign 1.50 mol dm(-3)) different sequences of regular and complex periodic and aperiodic oscillations were obtained. It is noticed that the bromine evaporation significantly affects the dynamics of the reaction.

In this study, in order to evaluate the quality and safety of selected commercial spices brands, contents of moisture and minerals, as well as the concentration of certain heavy metals (As, Hg and Pb) were determined in oregano, sweet basil, parsley and celery. The spice samples were subjected to microwave digestion, and were analyzed by atomic absorption spectrometry (AAS), using hydride generation AAS technique, cold vapor AAS technique, and graphite furnace AAS technique for determination of As, Hg and Pb, respectively. Maximum concentrations of As and Pb were determined in the same brand sample of celery, and are 0.75 ppm and 0.40 ppm, respectively, while the maximum concentration of Hg in various brands sweet basil samples is 0.05 ppm. According to the results, the contents of moisture and minerals, as well as the concentrations of heavy metals in all selected spices were below the maximum permissible limits declared by the national legislations, and are safe for human consumption. U ovom radu, u cilju određivanja kvaliteta i bezbednosti izabranih začina, određen je sadržaj vlage i ukupnih mineralnih materija, kao i koncentracije arsena (As), žive (Hg) i olova (Pb) u uzorcima origana, bosiljka, peršuna i celera. Koncentracije teških metala As, Hg i Pb, nakon mikrotalasne digestije, određene su različitim analitičkim tehnikama atomske apsorcione spektrometrije, primenom hidridne tehnike (As), tehnike hladne pare (Hg) i tehnike grafitne peći (Pb). Maksimalne koncentracije As i Pb određene su u istom uzorku celera i iznose 0,75 ppm i 0,40 ppm, respektivno, dok je maksimalna koncentracija Hg određena u uzorcima bosiljka i iznosi 0,05 ppm. U uzorcima začina, vrednosti sadržaja vlage, minerala i koncentracije ispitivanih teških metala su ispod maksimalno dozvoljenih vrednosti propisanih zakonskom regulativom Republike Srbije.

A phenomenon of current oscillators was characterized crosswise active-passive potential region during the electrodissolution of copper electrode in trifluoroacetic acid (TFA). The current density-potential curves show two transition points. A potential region of current oscillations was found as a part of limiting current region. The Cu vertical bar TFA electrochemical oscillator was found to displaying rich dynamical response on varying the temperature and the applied potential. The Cu vertical bar TFA system display current oscillation behaviour from the mono-periodic to the mixed-mode (relaxation type). Changes of the electrode surface structure and morphology were investigated by X-ray diffraction spectroscopy, atomic forced microscopy and optical microscopy.

Using a copper microelectrode of ∼5-μm diameter, the concentration of Se(IV) was determined by cathodic stripping voltammetry either from HClO 4 (0.1 M ) or from NaClO 4 (0.1 M ) supporting electrolytes. The preconcentration time of 15 s was chosen as optimal, and calibration graphs were constructed for the applied concentration interval 5 to 50 μ M. Satisfactory reproducibility was obtained, with a standard deviation for 5 μ M concentration ( n = 10) of about 4%.