Asymptotic charges in 3d gravity with torsion

We discuss some new developments in three-dimensional gravity with torsion, based on Riemann-Cartan geometry. Using the canonical approach, we study the structure of asymptotic symmetry, clarify its fundamental role in defining the gravitational conserved charges, and explore the influence of the asymptotic structure on the black hole entropy.Comment: 6 pages, LATEX file (+jpconf.cls,jpconf11.clo), Talk presented at Constrained Dynamics and Quantum Gravity 05, Cala Gonone (Sardinia, Italy), September 12-16, 200

An Alternative Construction of the Quantum Action for Supergravity

We develop a method to derive the on-shell invariant quantum action of the supergravity in such a way that the quartic ghost interaction term is explicity determined. First, we reinvestigate the simple supergravity in terms of a principal superfibre bundle. This gives rise to the closed geometrical BRST algebra. Therefore we determine the open BRST algebra, which realizes the invariance of the classical action. Then, given a prescription to build the full quantum action, we obtain the quantum BRST algebra. Together with the constructed quantum action this allows us to recover the auxiliary fields and the invariant extension of the classical action.Comment: 17 pages, No figure

Black hole entropy in 3D gravity with torsion

The role of torsion in quantum three-dimensional gravity is investigated by studying the partition function of the Euclidean theory in Riemann-Cartan spacetime. The entropy of the black hole with torsion is found to differ from the standard Bekenstein-Hawking result, but its form is in complete agreement with the first law of black hole thermodynamics.Comment: 17 pages, RevTeX, minor revision

Оne-dimensional maps of the complex and chaotic oscillations of Bray-Liebhafsky reaction

Cilj disertacije je razvijanje novih metoda obrade i korišćenja 1D mapa u analizi vremenskih serija dinamičkih sistema i njihova primena za razlikovanje različitih tipova dinamike u oscilatornoj reakciji Bray-Liebhafsky. U literaturi se navodi da se uspešnost modeliranja na bazi predloženog modela mehanizma posmatrane reakcije procenjuje na osnovu stepena usaglašenosti simuliranih rezultata sa eksperimentalnim rezultatima. Modeliranje oscilatornih reakcija koje se odigravaju u uslovima udaljenim od termodinamičke ravnoteže je dodatno otežano kompleksnošću ovih reakcija, odnosno činjenicom, da model mehanizma oscilatorne reakcije mora da opiše i brojne dinamičke fenomene karakteristične za nelinerane sisteme: pojavu predoscilatornog perioda, oscilacija, determinističkog haosa, bifurkacija, pobudljivosti oscilatornog sistema i ostale moguće oblike nelinearnosti. U literaturi postoje eksperimentalna i teorijska ispitivanja dinamičkih stanja oscilatorne BL rekacije. Teorijska ispitivanja su zasnovana na numeričkim simulacijama procesa, a na bazi pretpostavljenog modela BL reakcije. To je upravo urađeno u ovoj disertaciji za slučaj procesa u otvorenom-protočnom reaktoru. Rezultati su saglasni sa već postojećima da su dinamička stanja veoma osetljiva na promenu brzine protoka supstanci kroz reaktor, odnosno da se složena dinamička stanja nalaze u veoma uzanom opsegu vrednosti kontrolnog prametra j0, odnosno u uzanom delu koncentracionog faznog prostora. Dinamika složenih reakcionih sistema se može ispitivati na više načina. U literaruti i u disertaciji su opisani postupci: analiza vremenskih serija, analiza atraktora, bifurkaciona analiza, Poenkareovi preseci i jednodimenzione (1D) povratne (iteracione) mape. 1D povratne mape prikazuju dinamičku struktura Poenkareovog preseka preko zavisnost n+1-ve vrednosti posmatrane veličine u tački preseka atraktora od njene n-te vrednosti u prethodnoj tački preseka istog atraktora. Ove mape se relativno retko koriste u literaturi kao metoda za ispitivanje dinamičkih stanja reakcionih sistema, iako je kvalitativno ponašanje 1D mapa veoma korisno da objasni i čak i predvidi različite bifurkacije. U disertaciji se posebno razmatra prednost 1D mapa nad drugim metodama kada je potrebno utvrditi pri kojim protocima se javljaju periodična, a pri kojim...The aim of this Doctoral Dissertation is development of new methods 1D maps using in analysis of time series of dynamical systems and the application thereof to distinguish among different types of dynamics in oscillatory Bray-Liebhafsky reaction. The literature states that the success of the modeling based on the proposed model of the mechanism of the observed reactions, is estimated based on the degree of conformity of simulated results with experimental results. Modeling of oscillatory reactions, taking place under conditions far from thermodynamic equilibrium is further hampered by the complexity of these reactions, and the fact that model oscillatory reaction mechanism must describe a number of dynamic phenomena characteristic of nonlinear systems: the pressence of preoscillatory period, oscillations, deterministic chaos, bifurcation, excitability, oscillatory systems and other possible forms of nonlinearity. The literature records experimental and theoretical study of dynamics of oscillatory BL reactions. Theoretical studies are based on numerical simulations of the reaction process, based on the assumed model of BL reaction. This was exactly done in this dissertation, for the reaction in an open-flow reactor. The results are consistent with the existing ones, confirming dynamic states to be highly sensitive to changes in the flow rate of substances through the reactor, i.e the complex dynamic states range within narrow set of values of the control parameter j0, or in a narrow range of the concentration in phase space. The dynamics of complex reaction systems can be examined in several ways. The reference sources and Dissertation describes procedures: the analysis of time series, attractors analysis, bifurcation analysis, Poincare sections and one-dimensional (1D) (iteration) map. 1D return maps show the dynamic structure of the Poincare-section dependence through n + 1- values of the observed parameter in the attractor cut-point of its n-th value in the preceding cut-point of the same attractor section. These maps are relatively rarely used in the reference sources as a method for testing the dynamic state of the reaction system, although the qualitative behavior of 1D map is very useful in provding explanation, even predicting different bifurcations. The dissertation, ponders especially the advantage of 1D maps over other methods when it is necessary to determine periodical, i.e chaotic dynamic situation, i.e..

Теоријска предвиђања губитака енергије високо енергијских честица у кварк-глуонској плазми.

Today, it is considered that the reached collision energies in the ultra-relativistic heavy ion collisions (HIC) at the RHIC and the LHC are sufficiently high for the new state of matter − quark-gluon plasma (QGP), consisting of liberated quarks, antiquarks and gluons, to be created under controlled experimental conditions. Upon establishing that QGP is created, one of the main goals of heavy ion program at the RHIC and the LHC is understanding the properties of newly created state of matter. Thus created QGP is constituted of low-energetic particles, which represent 99.9% of quarks and gluons created in ultra-relativistic HIC. The remaining 0.1% are high-energy particles (tomographic probes), which are the subject of this thesis..

LEAD, MERCURY AND ARSENIC CONTENT IN SPICES: BLACK, WHITE AND GREEN PEPPER, BLACK CUMIN AND GINGER

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 ZAČINIMA: CRNI, BELI I ZELENI BIBER, CRNI KIM I ĐUMBIRU ovom radu, u cilju utvrđivanja bezbednosti odabranih komercijalnih začina, analizirane su koncentracije teških metala, kao i sadržaj vlage i ukupnih mineralnih materija, u uzorcima sušenog 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 začina iz lokalnih prodavnica u Beogradu, određene su nakon mikrotalasne digestije atomskom apsorcionom spektrometrijom (AAS), primenom tehnike grafitne peći (Pb), tehnike hladne pare (Hg) i hidridne tehnike (As). Određene koncentracije Pb, Hg i As u uzorcima sušenih začina 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 začina 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 teških 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.HIGHLIGHTSCommercially 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

Determination of the zinc and cadmium contents in low-alloyed tin

The method of anodic linear sweep voltammetry (ALSV) has been used to determine the content of Zn and Cd (up to 4% w/w) in eutectic type binary alloys with Sn. The alloy samples were prepared by casting. The effect of the type and the pH of the electrolyte, as well as of the sweep-rate on the dissolution of Zn and Cd from the alloy during an anodic potentinal-sweep was investigated. It was shown that ALSV is sensitive to low concentrations of both Zn and Cd in the investigated alloys, as well-defined peaks of the dissolution of the two metals were recorded before the massive dissolution of Sn commenced. Well-defined linear dependencies between the quantities of electricity under the dissolution peaks of Zn (Qzn) or Cd (Qcd) and the respective contents of the metals in the alloys were found. Intercepts at the abscissa were found in both investigated systems indicating the formation of solid solutions from which neither Zn nor Cd could be eluted. In both alloys, the smallest amount of the alloying component which could be detected was 0.25% (w/w). The application of the ALSV method has several advantages over other analytical methods: it is non-destructive as the dissolution involves only a very thin layer of the alloy; it requires simple and cheap instrumentation; it is fast and relatively sensitive. These make it suitable for routine analysis

Real null coframes in general relativity and GPS type coordinates

Based on work of Derrick, Coll, and Morales, we define a `symmetric' null coframe with {\it four real null covectors}. We show that this coframe is closely related to the GPS type coordinates recently introduced by Rovelli.Comment: Latex script, 9 pages, 4 figures; references added to work of Derrick, Coll, and Morales, 1 new figur

Hydrogen storage in a layered flexible [Ni2(btc)(en)2]n coordination polymer

[Ni2(btc)(en)2]n coordination polymer exhibits a layered two-dimensional structure with weak interaction between the layers. Correlation of experimental measurements, DFT calculations and molecular simulations demonstrated that its structural features, primarily the inherent flexibility of the layered polymeric structure, lead to improved hydrogen storage performance at room temperature, due to significant enhancement in isosteric heats of hydrogen adsorption. Volumetric measurements of hydrogen adsorption at room temperature show up to 0.3 wt.% hydrogen absorbed at 303 K and 2.63 bar of hydrogen pressure, with isosteric heats of adsorption of about 12.5 kJ mol−1. Predicted performance at room temperature is 1.8 wt.% at 48 bar and 3.5 wt.% at 100 bar, better than both MOF-5 and NU-100, with calculated values of isosteric heats for adsorption of hydrogen in 8–13 kJ mol−1 range at both 77 K and 303 K. Grand canonical Monte Carlo calculations show that this material, at 77 K, exhibits gravimetric hydrogen densities of more than 10 wt.% (up to 8.3 wt.% excess) with the corresponding volumetric density of at least 66 gL−1, which is comparable to MOF-5, but achieved with considerably smaller surface area of about 2500 m2 g−1. This study shows that layered two-dimensional MOFs could be a step towards MOF systems with significantly higher isosteric heats of adsorption, which could provide better room temperature hydrogen storage capabilities.This is the peer reviewed version of the following article: Blagojević, V.A., Lukić, V., Begović, N.N., Maričić, A.M., Minić, D.M., 2016, “Hydrogen storage in a layered flexible [Ni2(btc)(en)2]n coordination polymer”, International Journal of Hydrogen Energy, http://dx.doi.org/10.1016/j.ijhydene.2016.08.20