Some Resistive Properties of Novel Oxide Conductors Cu28-m Pbm-x Ax-p Mp Oy (A, M = Ba, Sr, Ag)

Oxide conductors have been prepared starting from the composition with the unit cell formula Cu24Pb4032 which corresponds to the compound with NaCl type structure referred to in the literature as mineral murdochite. The Pb4+ ions are partly substituted by ions of lower valency like Sr2+, Ba2+ and this results in oxidation of copper (Cu2+ Cu3+) which in turn esta blishes mixed valency states (MVS). The general unit cell formula Cu28-m Pbm_x Ax_p Mp Oy can be proposed and variation of parameters m, p, x with permutation of ions A and M results in a pronounced conductivity of samples at room temperature (RT). Some of them exhibit downturn of the electrical resistance (DER) by cooling from 230 K — 350 K. Since the electrical resistance is enhanced by application of higher current densities in the temperature range where the DER occurs, metallic derivatives of murdochite obtained by substitution of Cu and Pb can be used as interesting candidates for the searching of superconductivity (SC) at T > 200 K

Schlesinger transformations for elliptic isomonodromic deformations

Schlesinger transformations are discrete monodromy preserving symmetry transformations of the classical Schlesinger system. Generalizing well-known results from the Riemann sphere we construct these transformations for isomonodromic deformations on genus one Riemann surfaces. Their action on the system's tau-function is computed and we obtain an explicit expression for the ratio of the old and the transformed tau-function.Comment: 19 pages, LaTeX2

sl_2 Gaudin model with Jordanian twist

sl_2 Gaudin model with Jordanian twist is studied. This system can be obtained as the semiclassical limit of the XXX spin chain deformed by the Jordanian twist. The appropriate creation operators that yield the Bethe states of the Gaudin model and consequently its spectrum are defined. Their commutation relations with the generators of the corresponding loop algebra as well as with the generating function of integrals of motion are given. The inner products and norms of Bethe states and the relation to the solutions of the Knizhnik-Zamolodchikov equations are discussed.Comment: 22 pages; corrected typo

POLITICAL PARTIES IN MODERN DEMOCRACY - TERM AND ELEMENTS

Političke stranke su neophodan činilac demokratskih sistema. Autor u radu definiše pojam i osnovne elemente pojma političkih stranaka imajući u vidu političku i javnopravnu dimenziju. Autor analizira pet osnovnih elemenata koje su klasični i moderniji autori razmatrali prilikom definisanja političkih stranaka: ideologiju, izražavanje interesa socijalnih grupa, ostvarivanje državnog (nacionalnog) interesa, predlaganje kandidata na izborima za javnopolitičke funkcije, vršenje vlasti i stalnost. Prilikom razmatranja su posebno u obzir uzete društvene promene koje su uticale na promenu političkih stranaka, ali i celokupnog političkog sistema. Tako su određeni elementi koje su klasični teoretičari političkih stranaka smatrali suštinom nekadašnjih partija, poput ideologije i zastupanja interesa određenih socijalnih grupa, postali više simboličkog i lako promenljivog karaktera. U radu se otuda daje definicija koja sadrži nužne, konstitutivne elemente. Političke stranke se određuju kao postojana (stalna) organizacija koja isticanjem kandidata na izborima omogućava vršenje političke vlasti i sprovođenje određene politike koja se želi sprovesti kroz pravno obavezujuće odluke i norme.Political parties are a necessary component of democratic systems. In the paper, the author defines the concept and basic elements of the concept of political parties, keeping in mind the political and public legal dimension. The paper analyzes five basic elements that classical and more modern authors considered when defining political parties. These are: ideology, expression of interests of social groups, realization of state (national) interest, nomination of candidates in elections for public-political positions, exercise of power and permanence. During the discussion, the change of the political party, and therefore the entire political scene with the changes that took place in society through the development of the economy, consumer society and mass media, were taken into account. Thus, certain elements that classical theorists of political parties considered the essence of former parties, such as ideology and representation of the interests of certain social groups, became more symbolic and easily changeable. The paper therefore gives one definition containing the necessary, constitutive elements. Hence, political parties are defined as permanent (permanent) organizations that, by nominating candidates in elections, enable the exercise of political power and the implementation of certain policies that are to be implemented through legally binding decisions and norms

Metallothermic reduction in recycling technologies applied to the metallurgical byproducts and wastes

U većini slučajeva metalurški procesi su veoma kompleksni, tako da je formiranje međuproizvoda i opasnog otpada neizbežno. Kombinovanjem metalurških otpada i međuprodukata koje čine oksidni sistemi i metalni reducenati moguće je uspostaviti sinergiju koja se ogleda u iskorišćenju egzotermne energije reakcija i dobijanja korisnih proizvoda sa stanovišta životne sredine. Eksergijska analiza je korišćena za optimizovanu upotrebu različitih reducenata u elektrolučnoj peći, tako da se postignu minimalni gubici eksergije. Na osnovu eksperimentalnih rezultata razvijen je matematički model i softver za izračunavanje materijalnog i energetskog bilansa, količine redukcionog sredstva, viskoznosti i baziciteta šljake, adijabatske temperature i eksergijskog bilansa. U eksperimentalnom delu disertacije korišćeni materijali su: prašina iz postupka elektrolučnog topljenja čelika, kovarina, nestandardni talog jarosit PbAg, čelična prašina nastala obradom alatnog čelika, aluminijum kao amblažni otpad i opiljci magnezijuma. Sekundarni aluminijum u obliku folije je pripremljen na takav način da se oslobodi i razvije površina aluminijuma na dobijenim česticama praha. Detaljna karakterizacija dobijenih prahova je pokazala da se mogu koristiti za aluminotermijske reakcije. Magnezijum je dobijen iz fabrike za dobijanje magnezijuma iz sekundarnih sirovina. Pokazano je da mešanjem magnezijuma sa aluminijumom ima pozitivan uticaj na tok metalotermijskih reakcija. Rezultati su pokazali da se sekundarni aluminijum i magnezijum mogu uspešno koristiti za tretman opasnog otpada ili metalurških međuprizvoda na energetski efikasan način, koji je povoljan za životnu sredinu.In the most cases metallurgical processes are very complex, therefore formation of by-products and hazardous waste are inevitable. Simulating the reactions in a complex system can lead to self-sustaining and energy efficient treatment of wastes in recycling promoting manner. The synergic combination of oxide systems and metallic reducing agents originating from waste was researched, aiming to use exothermal energy of reactions and to obtain environmentally favorable products. Exergy analysis was used to optimize the use of different reducing agents in the electric-arc furnace, achieving minimal exergy losses. Based on the experimental results, mathematical model and software was developed to calculate material and energy balance, reducing agent amaunt, slag viscosity and density, adiabatic temperature and exergy balance. Electric arc furnace dust, non-standard jarosite PbAg, steel dust from tool steel industry, aluminum and magnesium from secondary sources was used in experimental part of dissertation. The secondary aluminum in the form of foil was prepared in different ways in order to develop and relieve the aluminum surface on the obtained powder particles. Brief characterization of this powders has shown that it is suitable for aluminothermic reactions. The magnesium was taken from secondary magnesium production industry in the form of the powder. Combining magnesium with aluminum powder has a positive influence on the metallothermic reduction reactions. Results are shown that the secondary aluminum and magnesium can be successfully used for a treatment of oxides bearing hazardous wastes and non-hazardous by-products in energy efficient and environmentally friendly manner

Supplementary data for the article: Kodranov, I. D.; Pergal, M. V.; Avdin, V. V.; Manojlović, D. D. Examination of Degradation and Ecotoxicology of Pethoxamid and Metazachlor after Chlorine Dioxide Treatment. Environ Monit Assess 2020, 192 (7), 422. https://doi.org/10.1007/s10661-020-08392-1

Supplementary material for: [https://doi.org/10.1007/s10661-020-08392-1]Related to published version: [http://cherry.chem.bg.ac.rs/handle/123456789/4007

Fleet renewal: An approach to achieve sustainable road transport

With more stringent requirements for efficient utilization of energy resources within the transport industry a need for implementation of sustainable development principles has appeared. Such action will be one of competitive advantages in the future. This is especially confirmed within the road transport sector. A methodology implemented in public procurement procedures for fleet renewal regarding the calculation of road vehicles’ operational lifecycle costs has been analyzed in detail in this paper. Afore mentioned calculation comprises the costs for: vehicle ownership, energy, carbon dioxide and pollutants emissions. Implementation of this methodology allows making the choice of energy efficient vehicles and vehicles with notable positive environmental effects. The objective of the research is to assess the influence of specific parameters of vehicle operational lifecycle costs, especially energy costs and estimated vehicle energy consumption, on vehicle choice in the procurement procedure. The case of urban bus fleet in Serbia was analyzed. Their operational lifecycle costs were calculated and differently powered vehicles were assessed. Energy consumption input values were defined. It was proved that defined fleet renewal scenarios could influence unquestionable decrease in energy consumption

Kinetics of barite reduction from refractory barite-sulphide ore

Refractory sulphide-barite ore was reduced with carbon in order to release lead, zinc, and copper sulphide from barite-pyrite base. Mineralogical investigations showed that due to the complex structural-textural relationships of lead, copper and zinc minerals with gangue minerals, it is not possible to enrich the ore using the conventional methods of mineral processing. The influence of temperature and time was studied to optimize the conditions, and to determine the kinetics of the barite reduction. The maximum removal of barite from ore was 96.7% at 900oC after 180 min. Chemically controlled kinetic model showed the best compliance with the experimental data. An activation energy of 142 kJ/mol was found

Arsenic removal from aqueous solutions by sorption onto zirconium- and titanium-modified sorbents

Arsenic reduction in drinking water can include treatment by adsorption, switching to alternative water sources, or blending with water that has a lower arsenic concentration. Commercial sorbents MTM, Greensand and BIRM (Clack Corporation) were modified with zirconium and titanium after activation. The modifications were performed with titanium tetrachloride and zirconium tetrachloride. The modified sorbents were dried at different temperatures. The sorption of arsenate and arsenite dissolved in drinking water (200μg L-1) onto the sorbents were tested using a batch procedure. After removal of the sorbent, the concentration of arsenic was determined by HG-AAS. Zirconium-modified BIRM showed the best performance for the removal of both arsenite and arsenate. Modification of the greensand did not affect arsenic sorption ability. Zirconium-modified BIRM diminished the concentration of total As to below 5 μg L-1

Algebraic Bethe Ansatz for deformed Gaudin model

The Gaudin model based on the sl_2-invariant r-matrix with an extra Jordanian term depending on the spectral parameters is considered. The appropriate creation operators defining the Bethe states of the system are constructed through a recurrence relation. The commutation relations between the generating function t(\lambda) of the integrals of motion and the creation operators are calculated and therefore the algebraic Bethe Ansatz is fully implemented. The energy spectrum as well as the corresponding Bethe equations of the system coincide with the ones of the sl_2-invariant Gaudin model. As opposed to the sl_2-invariant case, the operator t(\lambda) and the Gaudin Hamiltonians are not hermitian. Finally, the inner products and norms of the Bethe states are studied.Comment: 23 pages; presentation improve