Crown structure of Picea omorika trees in the plantation

The study was carried out in Serbian spruce (Picea omorika Panč/Purkynĕ) plantations in the western Serbia. The paper presents results of the analysis of crown development. The following elements were analyzed: total tree height, height of the crown base, absolute and relative crown length, maximal crown diameter, coefficient of crown spreading and degree of crown girth. We discuss approaches to the modeling of tree crown growth and development, growing under favorable environmental and stand conditions, without anomalies in development. In order to establish the relationship between analyzed factors, regression analyses were applied. Data fitting was by the analytic method, by the implementation of Prodan’s functions of growth, linear and parabolic function. Received models can be used for the simulation of various growth and developing processes in forest

Mineralni i polifenolni profil zelenog, crnog, biljnih i voćnih filter čajeva i njihov antioksidativni kapacitet

The aim of this doctoral dissertation was estimation of the antioxidant activity, polyphenol and mineral composition of black, green, herbal and fruit bagged teas. Heaving in mind the fact that different polyphenol compounds as antioxidants can react in vivo by various mechanisms, for determination of the total antioxidative activity was used several spectrophotometric tests (DPPH, ABTS, FRAP and RP) and electrochemical method - cyclic voltammetry. The antioxidant capacity of the analyzed samples was estimated using the antioxidant potency composite index (ACI). For identification and quantification of individual polyphenolic compounds, HPLC chromatography was used, and multi-element composition of bagged teas was determined by ICP-OES method. In order to differentiation analyzed bagged teas, methods of multivariate statistical analysis (PCA and CA) were used. In relation to the obtained results, analyzed bagged teas could contribute to the daily dietary requirements

Fractional Calculus Model of Electrical Impedance Applied to Human Skin

Fractional calculus is a mathematical approach dealing with derivatives and integrals of arbitrary and complex orders. Therefore, it adds a new dimension to understand and describe basic nature and behavior of complex systems in an improved way. Here we use the fractional calculus for modeling electrical properties of biological systems. We derived a new class of generalized models for electrical impedance and applied them to human skin by experimental data fitting. The primary model introduces new generalizations of: 1) Weyl fractional derivative operator, 2) Cole equation, and 3) Constant Phase Element (CPE). These generalizations were described by the novel equation which presented parameter (beta) related to remnant memory and corrected four essential parameters (R-0, R-infinity, alpha, tau(alpha)). We further generalized single generalized element by introducing specific partial sum of Maclaurin series determined by parameters (beta(*), gamma,delta ...). We defined individual primary model elements and their serial combination models by the appropriate equations and electrical schemes. Cole equation is a special case of our generalized class of models for beta* = gamma = delta = ... = 0. Previous bioimpedance data analyses of living systems using basic Cole and serial Cole models show significant imprecisions. Our new class of models considerably improves the quality of fitting, evaluated by mean square errors, for bioimpedance data obtained from human skin. Our models with new parameters presented in specific partial sum of Maclaurin series also extend representation, understanding and description of complex systems electrical properties in terms of remnant memory effects

Colloid electrohydrodynamics

This brief extracted review presents the recent development in basic and applied science and engineering of finely dispersed particles and related systems in general, but more profound and in-depth treatise are related to the liquid-liquid finely dispersed systems, i.e. emulsions and double emulsions. Twenty-five years ago, the idea, at first very fogy, came out from the pilot plant experiments related to the extraction Of uranium from wet phosphoric acid. In particular the solution of the entrainment problems, breaking of emulsions/double emulsions, as the succession of the extraction and stripping operations/processes, was performed In this pilot plant, secondary liquid-liquid phase separation loop was designed and carried out. The loop consisted of a lamellar coalescer and four flotation cells in series. Central equipment in the loop, relevant to this investigation, was the lamellar coalescer. The phase separation in this equipment is based on the action of external forces of mechanical and/or electrical origin, while adhesive processes at the inclined filling plates occur. Since many of related processes, e.g. adhesive processes, rupture processes and coalescence, were not very well understood, deeper research of these events and phenomena was a real scientific challenge

Rendgenološka procena apeksogeneze nakon primene hidroksiapatita

The treatment of pulp in teeth with incomplete apex formation is still a clinical challenge. In addition to the most widely used medication for this purpose, calcium hydroxide, other materials have also been tested. Following the use of synthetic biomaterials for restoring bone tissue, and considering their recognized biocompatibility and bioconductivity, our intention was to explore the possibility of using synthetic biomaterials in the endodontic treatment of permanent teeth with incomplete apex formation. The aim of this study was to observe the effectiveness of hydroxyapatite in apexogenesis of young permanent teeth. In this study a 100 µm synthetic hydroxyapatite material, Beohap (HAP) powder, was applied to 24 teeth in 3 dogs of 5.5 months of age, after incomplete root development was established on radiographs. The treated teeth were radiographed monthly and the radiographs compared with those of the corresponding teeth on the other side of the jaw until completion of apex growth. The tested teeth were divided into three groups according to the method of treatment: the first was direct pulp capping, the second was amputation of the pulp at the enamelcement junction and the third was high amputation at the radiographically identified point of root growth. On the basis of radiographic analysis, apex formation was successful in all test groups, with no significant differences between the three groups and the controls (Fisher's and χ 2 test). Deformities of the root apex were observed in two teeth (25%) in the third group.Tretman pulpe u vreme kada još uvek traje rast i razvoj korena predstavlja i dalje klinički izazov. Pored kalcijum hidroksida, najčešće i najduže upotrebljavanog medikamenta u ovakvim slučajevima, svakodnevno se testiraju i mnogi drugi materijali. Nakon što su se sintetski biomaterijali pokazali uspešnim u restauraciji koštnog tkiva uz njihovu priznatu biokompatibilnost i biokonduktivnost, naša namera je bila da istražimo mogućnost primene hidroksiapatita kao sintetskog biomaterijala u endodontskom tretmanu zuba sa nezavršenim rastom korena. U ovom istraživanju primenjen je Beohap, sintetski hidroksiapatit, prosečne veličine čestica =100 µm, aplikovan na 24 zuba sa nezavršenim rastom korena kod tri psa uzrasta 5,5 meseci. Uzrorci su kontrolisani radiografski i poređeni sa kontralateralnim netretiranim zubima do završetka rasta korena. Tretirani zubi su podeljeni u tri grupe: u prvoj je urađeno direktno prekrivanje pulpe, u drugoj je pulpa uklonjena do cementno-gleđne granice, a u trećoj je pulpa uklonjena do radiografski vidljivog vrha korena. Na osnovu analize rendgen filmova utvrđeno je da je formiranje vrha korena bilo završeno u sve tri grupe bez statističkih značajnosti razlika (Fisher's i χ 2 testovi) Deformiteti vrha korena uočeni su u 2 uzorka u trećoj grupi (25%)

A stochastic model of Min oscillations in Escherichia coli and Min protein segregation during cell division

The Min system in Escherichia coli directs division to the centre of the cell through pole-to-pole oscillations of the MinCDE proteins. We present a one dimensional stochastic model of these oscillations which incorporates membrane polymerisation of MinD into linear chains. This model reproduces much of the observed phenomenology of the Min system, including pole-to-pole oscillations of the Min proteins. We then apply this model to investigate the Min system during cell division. Oscillations continue initially unaffected by the closing septum, before cutting off rapidly. The fractions of Min proteins in the daughter cells vary widely, from 50%-50% up to 85%-15% of the total from the parent cell, suggesting that there may be another mechanism for regulating these levels in vivo.Comment: 19 pages, 12 figures (25 figure files); published at http://www.iop.org/EJ/journal/physbi

Iterative learning control with unknown time-delay

U ovom radu je prezentovan jedan novi algoritam upravljanja primenom iterativnog učenja (UIU) koji je nazvan upravljanje primenom 'prirodnog' iterativnog učenja. UIU je razvijen na bazi biološkog analogona - principa samopodešavanja. Dovoljni uslovi su izvedeni za konvergenciju predloženog algoritma upravljanja za jednu klasu nelinearnog, vremenski promenljivog sistema sa nepoznatim vremenskim kašnjenjem - jedan metalurški objekat sa nepoznatim kašnjenjem. Novi algoritam ima prednosti koje uključuju upravljanje objektom koji sadrži nepoznato kašnjenje, bolje osobine praćenja kao i povećanje brzine konvergencije željenom rešenju.The paper presents a new algorithm for iterative learning control (ILC) called 'natural' ILC. ILC is developed on the basis of a biological analog - the principle of self-adaptability. Sufficient conditions for the convergence of a new type of learning control algorithm for a class of time-varying delayed uncertain, non-linear systems - a process plant with unknown pure time-delay are presented. A new algorithm has benefits which include control of an object with unknown time-delay improving the properties of tracking, as well as the speed of convergence of ILC

Iterative learning control with unknown time-delay

U ovom radu je prezentovan jedan novi algoritam upravljanja primenom iterativnog učenja (UIU) koji je nazvan upravljanje primenom 'prirodnog' iterativnog učenja. UIU je razvijen na bazi biološkog analogona - principa samopodešavanja. Dovoljni uslovi su izvedeni za konvergenciju predloženog algoritma upravljanja za jednu klasu nelinearnog, vremenski promenljivog sistema sa nepoznatim vremenskim kašnjenjem - jedan metalurški objekat sa nepoznatim kašnjenjem. Novi algoritam ima prednosti koje uključuju upravljanje objektom koji sadrži nepoznato kašnjenje, bolje osobine praćenja kao i povećanje brzine konvergencije željenom rešenju.The paper presents a new algorithm for iterative learning control (ILC) called 'natural' ILC. ILC is developed on the basis of a biological analog - the principle of self-adaptability. Sufficient conditions for the convergence of a new type of learning control algorithm for a class of time-varying delayed uncertain, non-linear systems - a process plant with unknown pure time-delay are presented. A new algorithm has benefits which include control of an object with unknown time-delay improving the properties of tracking, as well as the speed of convergence of ILC

Concentrations of manganese and iron in some woody and herbs plants

Heavy metals are the substances that indicate environmental pollution. The plants polluted with heavy metals may endanger natural environment and cause health problems in humans. In our multidisciplinary research of the concentrations of pollutants in forest ecosystems and natural environment in Belgrade, we examined the contents of heavy metals essential for plants but harmful in greater concentrations on a long-term basis. The fact that heavy metals manganese and iron are accumulated in plants to the greatest extent focused our work on determination of the level of concentrations of Mn and Fe in the vegetative parts of 8 plant types on three locations on the Avala Mountain and one location in the centre of the city of Belgrade. The analyses of heavy metals contents in plants were performed by the method of flame atomic absorption spectrophotometry. The examination of the existence of important differences between the average values was performed by implementation of Duncan’s test for the level of significance of 95%. The current contents of heavy metals in plants in the area of the protected natural resource Avala do not represent danger that would presently cause notable damage to forests but show the tendency of the increase of concentrations. Therefore, this issue should be constantly monitored

Chemical heterogeneity of tomato inbred lines

Compositional characteristics of seven lines of tomatoes have been determined. The following parameters were evaluated: dry matter, acidity (citric acid equivalent), Ca-pectate, ash, cellulose, sugars (total, reducing sugars, sucrose), mineral substances (N, P, K, Ca, Na), surface color and carotenoid content. From a compositional viewpoint, there were no significant differences between lines, but in cellulose, sucrose, mineral substances, carotenoid content, and surface colour parameters, a*, b*, L and h°.