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Dependence of the Two-Photon Absorption Coefficient of Steel on the Pulse Duration During Its Ablation by Femto- and Picosecond Laser Pulses
No full textThe dependences of the depth of single-pulse ablation of the steel surface on the energy density of ultrashort laser pulses (0.3-12 ps) with a wavelength of 515 nm have the form different from the usual logarithmic one for linear absorption of radiation. Since the density of states of free conduction electrons in the s band is low, and the d band of strongly bound electrons with a high density of states is located around the Fermi level, these dependences have been approximated within the two-photon absorption model. The two-photon absorption coefficient increases almost linearly with the duration of laser pulses, which indicates the saturation of absorption and allows estimating the corresponding parameters of the electronic subsystem
Chemical Composition and Amino Acid Content in Different Genotypes of Wheat Flour
No full textThe purpose of this study was to evaluate the chemical parameters and amino acid content in 10 genotypes of soft Albanian wheat organically grown and collected during the summer seasons of 2014. The thin layer chromatography method was used for the identification the content of amino acids and spectrophotometry was used to determine the concentration of indentified amino acids. The results exhibited high protein content (13.73 % - 17.32 %) and relative high content of total amino acid content (6.3 % - 10.9 %). The most abundant of all amino acids was glutamic acid (in all genotypes) and cysteine (PZA 1, PZA 2, PZA 3, PZA 4, PZA 5, PZA 6, PZA 7, and PZA 10)
Biological activity of extracts of traditional wild medicinal plants from the Balkan Peninsula
No full textThe aim of the present study was to investigate antioxidant, cytotoxic and enzyme-inhibitory activities of wild growing medicinal herbs in the Balkan Peninsula (Morus nigra L., Symphytum officinale L., Sambucus nigra L., Teucrium chamaedrys L. and Teucrium montanum L.). Notably, antioxidant activity of investigated plant species was confirmed through several assays including free radical scavenging (ABTS), reducing power (CUPRAC), phosphomolybdenum and metal chelating test. Cytotoxic activity was evaluated using three different cell lines: Hep2c, RD and L2OB. S. officinale L. and S. nigra L. showed the highest cytotoxic activity. All studied extracts exhibited remarkable inhibitory effects on tested enzymes. S. nigra L. and T. chamaedrys L. exhibited the strongest tyrosinase inhibitory effects (26.62 +/- 0.77 extract and 14.72 +/- 0.41 mgKAEs/g, respectively), while S. officinale L. was the most potent in terms on a-glucosidase inhibition (11.47 +/- 0.05 mmol ACAE/g extract). The obtained results indicate that the extracts of the tested wild grown plants could be used which can be explored as natural medicines for the promotion of health
Novel Approach for Flavonoid Esters Production: Statistically Optimized Enzymatic Synthesis Using Natural Oils and Application in Cosmetics
No full textThe 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
Validation and uncertainty estimation of an analytical method for the determination of phenolic compounds in concrete
No full textOrganic contaminants from building materials negatively affect the health of people. This study presents an analytical method for the simultaneous identification and quantification of 9 phenolic compounds, i.e., phenol, 2-chlorophenol, 2,4-dimethylphenol, 2,4-dichlorophenol, 2,6-dichlorophenol, 4-chloro-3-methylphenol, 2,4,6-trichlorophenol, 2,3,4,6-tetrahlorophenol and pentachlorophenol, in concrete by a gas chromatographic method with mass spectrometric detection (GC-MS). By comparing the MS spectra of the test compounds with MS spectra of analytical standards, reliable identification was achieved. The method could be applied in a given range (from 0.01 to 7.5 mg kg(-1)) with appropriate parameters of precision, accuracy, repeatability and linearity. The developed method could be used for quality control testing of phenols in concrete during the construction of new buildings, old residences and construction waste. The measurement uncertainty of the phenolic compounds in concrete was evaluated using two approaches, i.e., GUM recommendations and a Monte Carlo method. Disagreement of those methods was observed. The Monte Carlo method could be used in the evaluation of combined measurement uncertainty for the determination of phenolic compounds in concrete
Isopiestic Determination of the Osmotic and Activity Coefficients of the {yNaH(2)PO(4)+(1-y)KH2PO4}(aq) System at T=298.15K
No full textIsopiestic measurements have been made for aqueous mixtures of NaH2PO4 and KH2PO4 at T=(298.15 +/- 0.01) K, at NaH2PO4 ionic strength fractions y=(0, 0.19108, 0.38306, 0.58192, and 1), assuming that both electrolytes dissociate as 1:1 electrolytes, using KCl(aq) as the reference standard solution. Model parameters for an extended form of Pitzer's ion-interaction model and also for the Clegg-Pitzer-Brimblecombe equations based on the mole-fraction-composition scale were evaluated at T=298.15K for NaH2PO4(aq) using the present isopiestic results (13 values), as were those for KH2PO4(aq) using the present isopiestic results (12 values), together with numerous critically-assessed osmotic coefficients for both electrolytes taken from the published literature. The thermodynamic models for KH2PO4(aq) extend to m=2.187molkg(-1), which is slightly above saturation, while those for NaH2PO4(aq) extend to m=7.5molkg(-1), which is below saturation. The 39 osmotic coefficients for the ternary mixtures from the present study along with 42 values from a published study were likewise represented with these models, with both the usual Pitzer mixing terms and also Scatchard's neutral-electrolyte model mixing terms being used for the extended ion-interaction model. Two mixing parameters were needed for each of the models, and all three models gave similar quality representations of the experimental results. Maximum differences in calculated values of mean molality-based activity coefficients for these three models are (+/-)(NaH2PO4)0.0080 and (+/-)(KH2PO4)0.0043. The experimental results were also found to nearly conform to Zdanovskii's rule
Importance of the valorisation of Serbian cultural and historical heritage of Kosovo and Metohija in the tourism development process
No full textNa teritoriji Kosova i Metohije postoje značajne pretpostavke za razvoj turizma kao specifične privredne grane. Ipak, potrebne planove nije moguće kreirati bez osnovne pretpostavke očuvanja srpskog kulturno-istorijskog nasleđa na ovom prostoru. Turistička valorizacija je svakako jedna od najznačajnijih tema teorije o turizmu. U radu se ističe značaj kulture i kulturne različitosti naroda i narodnosti (etničkih grupa) koje žive na teritoriji Kosova i Metohije. Rad ima značajnu pragmatičnu vrednost i predstavlja osnovu za definisanje strategije neophodne valorizacije kulturno-istorijskog nasleđa, ne samo s kulturnog, već i sa ekonomskog aspekta. Valorizacija je značajna kako bi se jasno definisali prioriteti u očuvanju bogatog kulturnog nasleđa za buduće generacije, imajući na umu nerešeno pitanje statusa pokrajine. U procesu normalizacije odnosa između Beograda i Prištine, uz posredstvo međunarodne zajednice ostaje nedvosmisleno jasna činjenica da je neophodno pronaći adekvatne modele zaštite kulturno-istorijskog nasleđa srpske zajednice. Zaključuje se da proces valorizacije u uslovima koji trenutno vladaju na Kosovu jeste veoma skup i komplikovan zadatak koji će se teško realizovati u bliskoj budućnosti. Rad predstavlja inicijativu za širu diskusiju o načinu turističke valorizacije bogatog kulturno-istorijskog nasleđa na način koji će zadovoljiti sve aktere na ovoj teritoriji.In the territory of Kosovo and Metohija there are important preconditions for the development of tourism as a specific economic activity. However, the premise for the development of pertaining plans is the preservation of cultural and historical heritage of Serbian and other ethnic groups in this area. Tourist valorisation is certainly one of the most important issues of tourism theory. The paper highlights the importance of protecting Serbian heritage and the heritage of other ethnic groups living in the territory of Kosovo and Metohija. The paper has significant pragmatic value as it provides the foundation for defining the strategy of the necessary valorization of cultural and historical heritage from cultural and economic perspectives. Valorisation is important in order to clearly define the priorities in preserving the rich cultural heritage for future generations, while acknowledging the unresolved political issue regarding the status of the province. In the process of normalising relations between Belgrade and Priština with the help of international community there is a clear and urgent need to create adequate models for protection of the Serbian heritage. The paper concludes that the process of valorisation in the current conditions of Kosovo is a very expensive and complicated task, which will make it difficult to implement in the near future. The paper calls for a wider discussion, one that will satisfy all interested parties, about tourist valorisation of rich cultural and historical heritage in this territory
Achieving high antimicrobial activity: Composite alginate hydrogel beads releasing activated charcoal with an immobilized active agent
No full textNew composites based on Ca-alginate hydrogels were produced that release activated charcoal (AC) particles with adsorbed povidone iodine (PVP-I) as a model antimicrobial substance in a physiological-like environment. Composite beads with different alginate (0.5-1.5% w/w) and AC (1-20% w/w) concentrations were analyzed by FE-SEM and characterized regarding textural parameters, swelling, and AC release kinetics. PVP-I was easily adsorbed onto AC particles within the optimized beads (0.5% w/w alginate, 20% w/w AC) as indicated by UV-vis spectroscopy, EDX and FT-IR analyses. The obtained beads have shown strong bactericidal effects against two standard bacterial strains (Staphylococcus aureus and Pseudomonas aeruginosa) and clinical multi-resistant wound isolates (MRSA, Escherichia coli, Pseudomonas aeruginosa, Enterococcus faecalis and Proteus mirabilis) and, at the same time, exhibited negligible PVP-I desorption in physiological saline solution. Thus, the obtained composites could provide utilization of potent antiseptics such as iodine, in wound dressings, without the concern of systemic absorption
Radioactivity level and concentration of metals in waters around power plants application of potential method for pollution assessment
No full textHuman activities may lead to increased levels of naturally occurring radioactive material and heavy metals in waters relative to undisturbed natural environment, consequently to reduced safety of environment. Therefore, evaluation of water quality from coal-fired power plants is essential to both environmental protection and protection of the human health. In this paper the concentrations of metals (K, Sr, and Pb) and corresponding radionuclides (K-40, Sr-90, and Pb-210) for 22 water samples in the vicinity of five coal-fired power plants in Serbia were determined. The total metal concentrations were measured using an atomic absorption spectrometer. The activities of radionuclides K-40 and Pb-210 were determined by gamma spectrometry using HPGe detector, while the activity of Sr-90 was determined by radiochemical analytical method and measured using low-level gas proportional counter. The water pollution status was assessed by the prospective method that is defined in this study. The preliminary results indicated that operation of the coal-fired power plants has no significant impact on the surrounding environment with regard to the radiological characteristics and content of metals of the investigated waters that can be used for suitable in future applications
Nutrient Composition of Three Mangulica Pork Cuts from Serbia
No full textThe purpose of this study was to analyze and evaluate the levels of essential elements (Mn, Fe, Cu, Zn, and Se) and proximate composition (moisture, protein, fat, and ash) of three pork cuts (loin, hind leg, and shoulder) from free-range Mangulica pigs from Serbia. Essential elements were determined by inductively coupled plasma mass spectrometry (ICP-MS). Shoulder contained the highest levels of essential elements (Mn, 0.192 mg kg(-1); Fe, 19.550 mg kg(-1); Cu, 1.490 mg kg(-1); Zn, 44.470 mg kg(-1); and Se, 0.130 mg kg(-1)). The shoulder and hind leg cut differed significantly from the loin in Mn, Fe, Cu, and Zn levels. This study showed that Mangulica pork is a rich source of Fe and Zn, and these elements showed significant correlations for a range of tissue combinations. The highest levels of protein (21.15 g/100 g) and fat (10.60 g/100 g) were established in loin, and the highest moisture level occurred in shoulder (72.02 g/100 g). Statistically, significant differences were established only between loin and shoulder in protein and fat contents