Olovo i kadmij u cigaretama i dimnom kondenzatu

The cigarettes of three commercial brands (belonging to JUS quality classes E, II and IV) were analysed for cadmium and lead in tobacco, butts and crude smoke condensate. Metal fractions transferred from the cigarette tobacco to the smoke as well as metal retentions in the butts were calculated from the analytical results. Statistical analyses revealed a significant dependence of all observables on the cigarette quality class.Metodom inverzne voltammetrije na visećoj živinoj kapi (DPASV) određene su količine kadmija i olova u cigaretama triju vrsta (kvalitetni razredi prema JUS-u: Extra, II i IV). Pored duhana, papira i filtarskih čepića analizirani su i opušci i sirovi dimni kondenzat. Iz analističkih rezultata izračunana je frakcija prijenosa metala iz duhana u dimni kondenzat kao J retencija metala u opušku. Statističkim analizama utvrđena je ovisnost svili opservabli o kvalitetnom razredu cigarete

Effects of Lifshitz Transition on Charge Transport in Magnetic Phases of Fe-Based Superconductors

The unusual temperature dependence of the resistivity and its in-plane anisotropy observed in the Fe-based superconducting materials, particularly Ba(Fe$_{1-x}$Co$_x$)$_2$As$_2$, has been a longstanding puzzle. Here we consider the effect of impurity scattering on the temperature dependence of the average resistivity within a simple two-band model of a dirty spin density wave metal. The sharp drop in resistivity below the N\'eel temperature $T_N$ in the parent compound can only be understood in terms of a Lifshitz transition following Fermi surface reconstruction upon magnetic ordering. We show that the observed resistivity anisotropy in this phase, arising from nematic defect structures, is affected by the Lifshitz transition as well.Comment: 8 pages, 5 figure

The research on the influence of the organizational culture on the effectiveness of quality improvement programs in the manufacturing companies

За рaзлику од претходних студија које су констатовале, али не и описале везу између програма унапређења квалитета и типологија организационе културе, ово истраживање идентификује димензије организационе културе, које имају значајан утицај на алате и методологије унапређења квалитета (димензије „културе квалитета“) и начин како димензије организационе културе и програма унапређења квалитета заједно утичу на пословне перформансе производних предузећа. Предложен модел утицаја тестиран је структурним једначинама на узорку од 200 производних организација у ланцу снабдевања канадске мултинационалне компаније. Резултати показују да улагање у запослене и њихово промовисање представља најутицајнију димензију организационе културе. Фокусирање на организационе циљеве и систем награђивања у организацији утичу једино на постепена унапређења дефинисана кроз Kaizen методологију. Када је ниво формализације у организацији висок, Kaizen и менаџмент тоталним квалитетом се користе интензивније. Супротно, када је ниво формализације у организацији низак, lean производња и интерна провера се користе интензивније. Добра комуникација у организацији условљава мање интензивно коришћење PDCA (Plan-Do-Check-Act) приступа, lean производње, корективних мера и и интерне провере. Уопштено говорећи, већина алата и методологија унапређења квалитета позитивно утиче на пословне перформансе предузећа. Резултати истраживања указују на то да организације могу да побољшају своје пословне перформансе са одговарајућим избором алата и методологија унапређења квалитета у зависности од постојећих димензија организационе културе и да такође могу да развију организациону културу која ће омогућити да иницијативе унапређења квалитета буду успешније.Unlike previous studies that have revealed a link between quality improvement programs and organizational culture typologies in individual companies, this study describes organizational culture dimensions that affect the use of quality improvement tools and methodologies and how both affect supply chain company performance. Structural equation modeling methods are applied to a sample of 200 organizations in the supply chain of a Canadian multinational company. The results show that employee promotion and investment constitutes the most influential cultural dimension. Organizational objectives and an employee reward system individually affect Kaizen. When the level of formalization in an organization is high, Kaizen and total quality management tools are used more intensively. When the level of formalization is low, lean manufacturing and internal audits are used more intensively. Superior communication in an organization causes PDCA (plan–do–check–act) approach, lean manufacturing, corrective actions and internal audits to be used less intensively. Generally speaking, most quality improvement tools and methodologies positively influence business performance. These results suggest that organizations can improve business performance levels by selecting appropriate quality improvement programs depending on existing organizational culture dimensions and may thereby develop an organizational culture that enables successful quality improvements

Sliding spin-density waves: studies of conduction noise, magnetic field dependence and Hall resistivity

We have studied the current-voltage characteristics of the (TMTSF)_2PF_6 in the spin density state (SDW), and in zero and finite external magnetic field. For the oscillating part of the nonlinear voltage response to the applied DC electric field, the fundamental frequency distribution (as a function of this field) and a nonlinear relation between the frequency and the SDW current reveal the growth of parallel conduction channels characterized by lower velocities and larger cross-sections. The number of fundamental frequencies, their amplitude and the level of low-frequency noise as well as the depinning behaviour provide a consistent indication of the sample inhomogeneities and associated local field variations, and might be well understood within the framework of the phase slippage model. The increase of the threshold electric field with the applied magnetic filed can be explained by the Bjeli-Maki theory, if the imperfect nesting is taken into account. Finally, the electric-field dependence of the Hall resistivity is consistent with the sliding mechanism of the SDW conduction

Hole-depletion of ladders in Sr14_{14}Cu24_{24}O41_{41} induced by correlation effects

The hole distribution in Sr$_{14}$Cu$_{24}$O$_{41}$ is studied by low temperature polarization dependent O K Near-Edge X-ray Absorption Fine Structure measurements and state of the art electronic structure calculations that include core-hole and correlation effects in a mean-field approach. Contrary to all previous analysis, based on semi-empirical models, we show that correlations and antiferromagnetic ordering favor the strong chain hole-attraction. For the remaining small number of holes accommodated on ladders, leg-sites are preferred to rung-sites. The small hole affinity of rung-sites explains naturally the 1D - 2D cross-over in the phase diagram of (La,Y,Sr,Ca)$_{14}$Cu$_{24}$O$_{41}$Comment: 6 pages, 8 figure

Application of artificial neural networks for modelling oxygen parameters of surface water quality

Održivo korišćenje i očuvanje prirodnih resursa postalo je imperativ modernog društva. Brojni antropogeni uticaji doveli su do pogoršanja kvaliteta slatkovodnih resursa, a naročito vodotokova koji predstavljaju jedan od glavnih izvora vodosnabdevanja. Evropske i nacionalne regulative uslovile su obavezu kontinuiranog praćenja stanja površinskih voda u vidu uspostavljanja i održavanja lokalnih i državnih mreža za monitoring kvaliteta voda, u cilju donošenja odluka zasnovanih na adekvatnim informacijama i pravovremenog reagovanja. U poslednje vreme, često se primenjuju modeli i odgovarajuće simulacione tehnike koje su sposobne da reše nelinearne probleme složenih sistema kao što je predviđanje parametara kvaliteta voda...Sustainable use and protection of natural resources have become an imperative of modern society. Numerous anthropogenic impacts have brought to deterioration of the quality of freshwater resources, especially watercourses, which represent one of the main water supply sources. European and national regulations have set requirements for continuous monitoring of the state of surface waters by establishing and maintaining local and state water quality monitoring networks, in order to provide adequate and informed decisionmaking as well as timely response. Lately, models and corresponding simulation techniques that are able to solve problems of non-linear complex systems, such as prediction of water quality parameters, are being often applied..

Klizni valovi spinske gustoce: proučavanje strujnog šuma, ovisnosti o magnetskom polju i Hallovog otpora

We have studied the current-voltage characteristics of the (TMTSF)2PF6 in the spin density state (SDW), and in zero and finite external magnetic field. For the oscillating part of the nonlinear voltage response to the applied DC electric field, the fundamental frequency distribution (as a function of this field) and a nonlinear relation between the frequency and the SDW current reveal the growth of parallel conduction channels characterized by lower velocities and larger cross-sections. The number of fundamental frequencies, their amplitude and the level of low-frequency noise as well as the depinning behaviour provide a consistent indication of the sample inhomogeneities and associated local field variations, and might be well understood within the framework of the phase slippage model. The increase of the threshold electric field with the applied magnetic filed can be explained by the Bjeli-Maki theory, if the imperfect nesting is taken into account. Finally, the electric-field dependence of the Hall resistivity is consistent with the sliding mechanism of the SDW conduction.Proučavali smo karakteristike napon – struja materijala (TMTSF)2PF6 u stanju valova spinske gustoće (SDW). Za oscilatorni dio nelinearnog naponskog odziva na istosmjerno električno polje, osnovna frekventna raspodjela (kao funkcija tog polja) i nelinearan odnos frekvencije i SDW struje pokazuju rast usporednih kanala vođenja označenih manjim brzinama i većim udarnim presjecima. Broj osnovnih frekvencija, njihove amplitude i razina niskofrekventnog šuma, kao i otkočno ponašanje sustavno pokazuju na nehomogenosti uzorka i pridružene varijacije lokalnog polja, i mogu se shvatiti u okviru modela klizne faze. Rast praga električnog polja s magnetskim poljem može se protumačiti Bjeliš-Makijevom teorijom, ako se uzme u obzir ugniježdenje. Konačno, nalazimo da je ovisnost Hallovog otpora o električnom polju u skladu s kliznim mehanizmom SDW vođenja struje