Electron-phonon coupling in crystalline organic semiconductors: Microscopic evidence for nonpolaronic charge carriers

We consider electron(hole)-phonon coupling in crystalline organic semiconductors, using naphthalene for our case study. Employing a first-principles approach, we compute the changes in the self-consistent Kohn-Sham potential corresponding to different phonon modes and go on to obtain the carrier-phonon coupling matrix elements (vertex functions). We then evaluate perturbatively the quasiparticle spectral residues for electrons at the bottom of the lowest-unoccupied- (LUMO) and holes at the top of the highest-occupied (HOMO) band, respectively obtaining $Z_e\approx 0.74$ and $Z_h\approx 0.78$. Along with the widely accepted notion that the carrier-phonon coupling strengths in polyacenes decrease with increasing molecular size, our results provide a strong microscopic evidence for the previously conjectured nonpolaronic nature of band-like carriers in these systems.Comment: final, published versio

Risk Factors for Neonatal Sepsis and Method for Reduction of Blood Culture Contamination

Background: False-positive blood cultures findings may lead to a falsely increased morbidity and increased hospital costs.Method: The survey was conducted as retrospective - prospective study and included 239 preterm infants (born before 37 weeks of gestation) who were treated in Neonatal Intensive Care Unit (NICU) in Institute for Child and Youth Health Care of Vojvodina during one year (January 1st, 2012 to December 31st, 2012). The retrospective part of the study focused on examination of incidence of neonatal sepsis and determination of risk factors. In the prospective part of the study infants were sub-divided into two groups: Group 1- infants hospitalized in NICU during the first 6 months of the study; blood cultures were taken by the ‘’clean technique’’ and checklists for this procedure were not taken. Group 2- neonates hospitalized in NICU during last 6 months of the study; blood cultures were taken by ‘’sterile technique’’ and checklists for this procedure were taken.Results: The main risk factors for sepsis were prelabor rupture of membranes, low gestational age, low birth weight, mechanical ventilation, umbilical venous catheter placement, and abdominal drainage. Staphylococcus aureus and coagulase negative Staphylococcus were the most frequently isolated microorganisms in false-positive blood samples.Conclusions: Education of employees, use of checklists and sterile sets for blood sampling, permanent control of false positive blood cultures, as well as regular and routine monthly reports are crucial for successful reduction of contamination rates

Thermal mass impact on energy performance of a low, medium and heavy mass building in Belgrade

Heavy mass materials used in building structures and architecture can significantly affect building energy performance and occupant comfort. The purpose of this study was to investigate if thermal mass can improve the internal environment of a building, resulting in lower energy requirements from the mechanical systems. The study was focused on passive building energy performance and compared annual space heating and cooling energy requirements for an office building in Belgrade with several different applications of thermal mass. A three-dimensional building model was generated to represent a typical office building. Building shape, orientation, glazing to wall ratio, envelope insulation thickness, and indoor design conditions were held constant while location and thickness of building mass (concrete) was varied between cases in a series of energy simulations. The results were compared and discussed in terms of the building space heating and cooling energy and demand affected by thermal mass. The simulation results indicated that with addition of thermal mass to the building envelope and structure: 100% of all simulated cases experienced reduced annual space heating energy requirements, 67% of all simulated cases experienced reduced annual space cooling energy requirements, 83% of all simulated cases experienced reduced peak space heating demand and 50% of all simulated cases experienced reduced peak space cooling demand. The study demonstrated that there exists a potential for reducing space heating and cooling energy requirements with heavy mass construction in the analyzed climate region (Belgrade, Serbia)

Study on a standard for grounding systems realization

Grounding systems of objects inside power facilities are very often realized as structures consisting of protective electrodes’ system placed in the object foundation, and neutral electrodes’ system placed at a specified distance from the object. Official standards and publications recommend a minimal value for the distance between the protective and the neutral part of grounding structures, so that the influence of one on another can be neglected. We analyze several practical implementations of grounding structures and demonstrate that the minimal distance is actually much smaller than that recommended by the standards

The role of the textbooks in the process of acquiring music literacy in lower grades of primary school students

Циљ овог рада представља добијање конкретних сазнања о заступљеним мето- дичким приступима и о квалитету садржаја у савременим уџбеницима музичке културе различитих издавача (Едука, Завод за уџбенике, Клет и Креативни центар) намењених музичком описмењавању ученика млађег школског узраста ради стварања основе за унапређивање уџбеничких комплета за наставу музичке културе. До одређених сазнања дошли смо помоћу формираних критеријума (систем категорија) за процену квалитета уџбеника музичке културе од првог до четвртог разреда општеобразовне школе у дефинисаној области почетна музичка писменост. Конкретни резултати добијени су спровођењем два истраживања: 1) анализа уџбеничких комплета различитих издавача помоћу конструисаних инструмената за две супстанцијалне уџбе- ничке јединице у процесу музичког описмењавања – уџбеник и носач звука (CD) и 2) испитивање мишљења учитеља (N = 340) о корисности компонената уџбеника за процес музичког описмењавања које смо реализовали помоћу конструисаног анкетног упитника (УМО 016). У раду се примењује дескриптивна метода, метода теоријске анализе, квантита- тивна и квалитативна анализа. При обради података коришћени су поступци и показате- љи дескриптивне статистике: дистрибуција учесталости, мере учесталости (фреквенције и проценти), мере просека (аритметичка средина) и процена варијабилности (стандардна девијација). Подаци анализе јединица садржаја уџбеничког комплета обрађени су фре- квенцијски и процентуално. На основу добијених резултата анализе уџбеничких комплета сазнајемо да сви издавачи примењују принцип рада од звука ка нотној слици, да примењују различите методичке приступе у реализацији потребних садржаја и да су заступљени садржаји у уџбенику из угла музичког описмењавања неуједначеног квалитета. Налази истраживања мишљења учитеља о квалитету, односно о степену корисности одређених компонената уџбеника за музичко описмењавање добијених посредством анкетног упитника у потпу- ности се подударају са нашим теоријским разматрањем проблема...The aim of this thesis is gaining thorough knowledge about the applied methodological approaches in the quality of contents in the contemporary Music culture textbooks of different publishers (Еduka, Zavod za udzbenike, Klet and Kretaivni centar), aimed at musical literacy of the lower grades primary school students, for the purpose of making a solid foundation for improving resource packs for teaching Musical culture. Certain knowledge was gained by the formed criteria (category system) for evaluation the quality of the Music culture textbooks in the lower grades (1st-4th) of the primary school in the defined field of the initial musical literacy. The definite results were gained by conducting two types of the research: 1) analysis of different textbooks with resource packs of different publishers by the aid of constructed instruments for two substantial textbook units in the process of obtaining musical literacy – text book with the audio recording (CD) and 2) examining the teachers' attitudes (N = 340) about the usefulness of the units of the course book for the process of obtaining musical literacy, realised by the constructed questionnaire (UMO 016). In the paper, we are applying descriptive method, method of theoretical analysis, quantitative and qualitative analysis. Data processing included the procedures and descriptors of descriptive statistics: distribution of the frequency, measures of frequency (frequencies and percentage), arithmetical mean and estimation of variability (standard deviation). Data of the analysis of the units of the contents are processed in frequency and percentage. Based on the given results of the analysis of the textbooks with recourse packs, we learnt that the authors of the stated publishers applied the principle of work from sound to the note picture, different methodological approaches in realisation of the needed contents, and that the applied contents in the textbooks from the angle of musical gaining literacy, and of an unequal quality. Findings of the research of thoughts of teachers about the quality, i.e. the degree of usefulness of certain textbook of Musical gaining literacy components were obtained by the means of the questionnaire and fully match our theoretical discussion of the problem. Results of the teachers' replies about the textbooks they mostly choose and use in their teaching and the results of the quantitative-qualitative research of the textbook from the aspect of musical gaining literacy of students do not rank the four publishers in the same order. Results of the systematically organised and scientifically founded analysis of substantial textbook units for work with sound (textbook and a CD) are not in accordance with the results gathered about teachers' attititudes and they are in favour of two publishers' resource packs which are not very frequently used in teaching..

The review of some novel biomarkers in sedimentary organic matter

A series of novel C33-C35 hexacyclic benzohopanes have been identified in coals and crude oils of different ages from all over the world [1]. They differ from regular benzohopanes by the presence of methyl group in position C-31. These compounds are more abundant in coals and terrestrial oils. The investigation also showed that mature samples have distributions of benzohopanes distinct from immature ones, which are characterised by a greater number of benzohopane isomers. Although exact structures of the additional isomers were not determined, it seems they were formed by an isomerisation of alkyl groups attached to the aromatic ring. Two novel monoaromatic hydrocarbons (MW = 270; basic fragment ions m/z 255 and 146) were identified in coals, mudstones and crude oils. Their structures were determined as cis- and transicetexa-8,11,13-trienes (or dehydroicetexanes) using NMR spectroscopy. Dehydroicetexanes are potential biomarkers of Cupressaceae (cypress conifers). Benzo[b]naphtho[d]furans (BNFs) have been identified in oils, condensates, source-rocks, coals and coaly shales, being more abundant in the latter. We detected BNFs (m/z 218) in relatively high amounts in the aromatic fractions of pyrolysates of brown coals which attained the maturity corresponding to vitrinite reflectance of 1.80 %Rr [2]. This result suggests that BNFs can be attractive for investigations of mature fluids that originate from gas/condensate prone sources, rich in type III kerogen, which are usually depleted in biomarkers. Recently, it was observed that [2,1]/[1,2]BNF ratio can be used to describe lithofacies [3]. This ratio is much lower in sediments from fluvial-deltaic systems than in clay-depleted sediments from marine environments. 1-Chloro-n-alkanes (m/z 91) have been identified in saltmarsh vegetation, recent sediments from estuarine setting and freshwater lake sediments [4]. Despite their absence in the investigated crude oils, we identified a series of 1-chloro-n-alkanes in pyrolysates of the corresponding asphaltenes, obtained at 250 oC. This result indicates very good preservation of biomarkers occluded inside asphaltenes and announces a possible application of 1-chloro-n-alkanes in correlation studies.Invited Lectur

Varijabilnost proizvodnih osobina izdvojenih linija pčela u zapadnoj Srbiji

Condition for achieving high performance results in beekeeping is focused on the use of high-quality breeding queen bee. Because that a large amount of research are based on the examination of properties of selected lines of bees and choosing the best queen mothers in the aim of selection and improving the production characteristics of honey bees from the territory of Serbia. The amount of bees, brood, honey and pollen was investigated in two spring and one autumn survey and productivity controlled in the pasture of accacia. Line 1 had the greatest amount of brood (1.23, 4.04 and 5.39), while line 3 had the best spring development. The best quality of brood in all three exams had the lines 1 and 3 (3.00, 3.00 and 2.95) as well as the best productivity compared to the average yield of all other three lines. All tested lines were exhibited variability, which provides enough possibility for their further improvement and single out the mother queenbees with best results.U dvogodišnjem istraživanju ispitivano je četiri odabrane linije medonosne pčele na području Zapadne Srbije. Proizvodne karakteristike praćene su prema standardnoj metodologiji. Na osnovu rezultata istraživanja utvrđeno je da je najveću površinu pčela imala linija 1 (u jesenjem i prvom prolećnom pregledu: 2,10 i 3,27 rama), dok je u drugom prolećnom pregledu najviše pčela imala linija 3 (6,19 rama). Utvrđene razlike u površini pčela nisu bile statistički značajne (P>0.01). Najbolji prolećni razvoj legla između prva dva prolećna pregleda utvrđen je u liniji 3 (povećanje za 1,4 rama) i liniji 1 (povećanje za 1,35 rama). Najveću površinu meda i polena imala su društva linije 1. Najbolji kvalitet legla, po pregledima utvrđen je u linijama 1 i 3. Na osnovu rezultata istraživanja, utvrđeno je da su linija 1 i 3 imale najbolje proizvodne karakteristike. Postojeća varijabilnost ispitivanih karakteristika pčela pruža mogućnost daljeg usavršavanja linija i širenja genetskog napretka na području Srbije, pri čemu prednost treba dati umnožavanju matica na bazi biološkog materijala pčela linija 1 i 3

Oxidation-induced Spin Probes in Low-density Lipoproteins

PBN trapping indicated the presence of at least two types of radicals induced in LDL upon slow oxidation, as observed with EPR spectroscopy. The EPR spectra are very similar to those of the spin probes or spin labels, which are routinely used in the studies of macromolecular systems and supramolecular assemblies. The parameters of the spectral line shapes, treated in two different theoretical models, did not provide conclusive evidence for the phase transition in the LDL particles, known to be present at about 25 °C. It is concluded that both types of trapped radicals, or at least one of them, are associated with the apolipoproteins, with the spin probe sticking into the lipid domain of phospholipids

Study of barium bismuth titanate prepared by mechanochemical synthesis

Barium-bismuth titanate, BaBi4Ti4O15 (BBT), a member of Aurivillius bismuth-based layer-structure perovskites, was prepared from stoichiometric amounts of barium titanate and bismuth titanate obtained via mechanochemical synthesis. Mechanochemical synthesis was performed in air atmosphere in a planetary ball mill. The reaction mechanism of BaBi4Ti4O15 and the preparation and characteristics of BBT ceramic powders were studied using XRD, Raman spectroscopy, particle analysis and SEM. The Bi-layered perovskite structure of BaBi4Ti4O15 ceramic forms at 1100 °C for 4 h without a pre-calcination step. The microstructure of BaBi4Ti4O15 exhibits plate-like grains typical for the Bi-layered structured material and spherical and polygonal grains. The Ba2+ addition leads to changes in the microstructure development, particularly in the change of the average grain size

Kinetics and mechanism of sphalerite leaching by sodium nitrate in sulphuric acid solution

Interest for application of hydrometallurgical processes in a processing of complex sulphide ores and concentrates has increased in recent years. Their application provides better metal recoveries and reduced emission of gaseous and toxic ageneses in the environment. The kinetics and mechanism of sphalerite leaching from complex sulphide concentrate with sulphuric acid and sodium nitrate solution at standard conditions was presented in this paper. The influences of temperature and time on the leaching degree of zinc were investigated and kinetic analysis of the process was accomplished. With temperature increasing from 60 to 90°C, the zinc leaching increased from 25.23% to 71.66% after 2 hours, i.e. from 59.40% to 99.83% after 4 hours. The selected kinetic model indicated that the diffusion through the product layer was the rate-controlling step during the sphalerite leaching. The activation energy was determined to be 55 kJ/mol in the temperature range 60-90°C. XRD, light microscopy and SEM/EDX analyses of the complex concentrate and leach residue confirmed formation of elemental sulphur and diffusion-controlled leaching mechanism