Fermi level quantum numbers and secondary gap of conducting carbon nanotubes

For the single-wall carbon nanotubes conducting in the simplest tight binding model, the complete set of line group symmetry based quantum numbers for the bands crossing at Fermi level are given. Besides linear (k), helical (k'} and angular momenta, emerging from roto-translational symmetries, the parities of U axis and (in the zig-zag and armchair cases only) mirror planes appear in the assignation. The helical and angular momentum quantum numbers of the crossing bands never vanishes, what supports proposed chirality of currents. Except for the armchair tubes, the crossing bands have the same quantum numbers and, according to the non-crossing rule, a secondary gap arises, as it is shown by the accurate tight-binding calculation. In the armchair case the different vertical mirror parity of the crossing bands provides substantial conductivity, though kF is slightly decreased.Comment: 6 pages, 2 figure

Fluctuations in superconducting rings with two order parameters

Starting from the Ginzburg-Landau energy functional, we discuss how the presence of two order parameters and the coupling between them influence a superconducting ring in the fluctuative regime. Our method is exact, but requires numerical implementation. We also study approximations for which some analytic expressions can be obtained, and check their ranges of validity. We provide estimates for the temperature ranges where fluctuations are important, calculate the persistent current in magnesium diboride rings as a function of temperature and enclosed flux, and point out its additional dependence on the cross-section area of the ring. We find temperature regions in which fluctuations enhance the persistent currents and regions where they inhibit the persistent current. The presence of two order parameters that can fluctuate independently always leads to larger averages of the order parameters at Tc, but only for appropriate parameters this yields larger persistent current. In cases of very different material parameters for the two coupled condensates, the persistent current is inhibited

Carbon Nanotubes Band Assignation, Topology, Bloch States and Selection Rules

Various properties of the energy band structures (electronic, phonon, etc.), including systematic band degeneracy, sticking and extremes, following from the full line group symmetry of the single-wall carbon nanotubes are established. The complete set of quantum numbers consists of quasi momenta (angular and linear or helical) and parities with respect to the z-reversal symmetries and, for achiral tubes, the vertical plane. The assignation of the electronic bands is performed, and the generalized Bloch symmetry adapted eigen functions are derived. The most important physical tensors are characterized by the same set of quantum numbers. All this enables application of the presented exhaustive selection rules. The results are discussed by some examples, e.g. allowed interband transitions, conductivity, Raman tensor, etc.Comment: 11 pages, 2 figures, 2 tables; pdf available from: http://www.ff.bg.ac.yu/qmf/qsg_e.ht

Aerosol synthesis of phosphor based on Eu3+ activated gadolinium oxide matrices

Poster presented at the Seventh International Conference on Ceramic Processing Science, Inuyama, Japan, May 15-18, 200

Aerosol synthesis of phosphor based on Eu3+ activated gadolinium oxide matrices

Poster presented at the Seventh International Conference on Ceramic Processing Science, Inuyama, Japan, May 15-18, 200

Kinetics of nanocrystalline phase transformations in spray pyrolysed ZnO particles

The thermal behavior of ZnO powder obtained by ultrasonic spray pyrolysis of nitrate solution (c=0.8mol/dm3, D0=2.695µm, Tmax=6000C, FG=1.2dm3/min) was investigated using non-isothermal differential scanning calorimetry (DSC, heating rates 5, 10, 15, 20O/min). The exothermic heat effects at the temperature range from 350 to 5000C were linked to particles structural data obtained by XRD, SEM and TEM analysis. Produced particles are characterized by uniform submicronic size (D=800nm, BET=4.94m2/g), high phase purity and granular or circular “open” surface due to the presence of primary crystallites (d= 20nm). Observed structural changes during heating of this powder were attributed to simultaneous processes of nucleation and growth of primary crystallites inside the produced particles

Phrasal verbs with particles in, out, on and off in the English languge: a cognitive-linguistic analysis ; Фразовые глаголы с частицами in, out, on и off в английском языке: когнитивно-лингвистический анализ

Predmet istraţivanja u ovom radu jesu frazni glagoli sa partikulama IN, OUT, ON i OFF u savremenom engleskom jeziku koji su analizirani u okviru teorijskih postavki kognitivne lingvistike. Istraţivanje ima nekoliko ciljeva: da se utvrdi znaĉenjska struktura posmatranih fraznih glagola, da se ispita motivisanost polisemije posmatranih fraznih glagola sa stanovišta kognitivnih mehanizama koji leţe u osnovi proširenja znaĉenja i sa stanovišta semantiĉke interakcije izmeĊu sastavnog glagola i partikule, kao i da se ispitaju znaĉenjski odnosi izmeĊu fraznih glagola koji sadrţe partikule suprotnog znaĉenja. U prvom poglavlju opisani su predmet i ciljevi istraţivanja, navedene osnovne informacije u vezi sa korpusom, kao i razlozi za odabir kognitivnolingvistiĉkog pristupa u ispitivanju posmatranih leksiĉkih jedinica...This dissertation is aimed at exploring phrasal verbs with particles IN, OUT, ON and OFF in the contemporary English language, which are analysed within the theoretical framework of cognitive linguistics. There are several research goals: to determine the semantic structure of the phrasal verbs under examination, to investigate the motivation of the polysemy of the phrasal verbs under examination viewed both from the perspective of the cognitive mechanisms undelying their meaning extensions and the semantic interaction between the constituent verb and constituent particle, and to investigate the semantic relations between the phrasal verbs containing particles opposite in meaning. The subject and the goals of the investigation are described in Chapter One alongside with the basic information on the corpus and the reasons for choosing a cognitive-linguistic approach in the investigation of the lexical units under examination..

Degree of fertilization and biological traits of new plum cultivars (Prunus domestica L.)

Код три новије сорте шљиве (‘Jojo’, ‘Hanita’ и ‘Katinka’), толерантне или отпорне на вирус Шарке (Plum Pox Virus), испитиванe су најзначајније биолошке особине и квантитативни раст поленових цевчица in vivo и in vitro у условима самоопрашивања, слободног опрашивања и страног опрашивања при различитим температурама (20°C, 23°C и 26°C). Такође, у овим условима испитивани су бујност стабла, компоненте приноса и физичко-хемијске карактеристике плода шљиве. Истраживања су обављена од 2008. до 2010. године у засаду шљиве у тзв. густој садњи у агроеколошким условима Чачка (западна Србија) коришћењем стандардне методологије. Сорта ‘Hanita’ је имала најпозније цветање током све три године, а најмање варирање ове особине је утврђено код сорте ‘Jojo’. Највећа клијавост полена је установљена у сорте ‘Hanita’, средња у сорте ‘Jojo’, а најмања у сорте ‘Katinka’. Најмањи број поленових цевчица у горњој трећини стубића код свих испитиваних сорти је утврђен при самоопрашивању. У погледу ове особине, најбољи опрашивач за сорту ‘Jojo’ била је сорта ‘Hanitа’, за сорту ‘Katinka’ сорта ‘Jojo’, док је сорта ‘Hanita’ највећи број поленових цевчица имала при слободном опрашивању. Када је у питању заступљеност поленових цевчица у појединим регионима тучка, сорта ‘Katinka’ се показала као најбољи опрашивач сорти ‘Jojo’ и ‘Hanita’, док је сорта ‘Hanita’ била најбољи опрашивач сорте ‘Katinka’. Највеће иницијално и финално заметање плодова код сорти ‘Hanita’ и ‘Katinka’ утврђено је приликом слободног опрашивања, а код сорте ‘Jojo’ у комбинацији опрашивања поленом сорте ‘Katinka’, односно при самоопрашивању. На константним температурама (20°C, 23°C и 26°C), сорта ‘Hanita’ је била најбољи опрашивач сорте ‘Jojo’, сорта ‘Jojo’ је била најбољи опрашивач сорте ‘Hanita’, док су ове две сорте биле подједнако добри опрашивачи сорте ‘Katinka’. Код сорти ‘Jojo’ и ‘Hanita’, најбољи раст поленових цевчица је утврђен на константној температури од 23°C, а код сорте ‘Katinka’ на температури од 26°C. Највећи принос по стаблу и јединици површине је утврђен код сорте ‘Hanita’, а најмањи код сорте ‘Katinka’, међутим највећи коефицијент родности је утврђен код сорте ‘Jojo’ која је имала најмању бујност стабла...Three recently developed plum cultivars (‘Jojo’, ‘Hanita’ and ‘Katinka’), tolerant or resistant to Plum Pox Virus, were evaluated for major biological traits and pollen tubes growth in vivo and in vitro under self-, open- and cross-pollination at different temperatures. Tree vigour, yield components, physical and chemical attributes of the fruit were also analysed under these conditions. Research was conducted during 2008-2010 in a high density planting system under the environmental conditions of Cacak (Western Serbia) using standard methods. The latest flowering was observed in ‘Hanita’ during the three years, whereas ‘Jojo’ showed lowest variations in flowering date. Fruit maturity date was earliest in ‘Katinka’ and latest in ‘Jojo’. Pollen germination was highest in ‘Hanita’, medium in ‘Jojo’, and lowest in ‘Katinka’. The lowest number of pollen tubes in the upper part of the style in all cultivars was found under self-pollination. As regards this trait, ‘Hanita’ and ‘Jojo’ were the best pollenizers for ‘Jojo’ and ‘Katinka’, respectively, whereas ‘Hanita’ developed the highest number of pollen tubes under open-pollination. As regards the percentage of pollen tubes in different parts of the pistil, ‘Katinka’ proved to make the best pollenizer for ‘Jojo’ and ‘Hanita’, and ‘Hanita’ for ‘Katinka’. The highest initial and final fruit set in cultivars ‘Hanita’ and ‘Katinka’ was observed under open-pollination and in ‘Jojo’ under cross-pollination by pollen of ‘Katinka’ and self-pollination. At constant temperatures (20°C, 23°C and 26°C), ‘Hanita’ and ‘Jojo’ made the best pollenizers for ‘Jojo’ and ‘Hanita’, respectively, and equally good pollenizers for ‘Katinka’. The rate of pollen tubes growth was highest at a constant temperature of 23°C in ‘Jojo’ and ‘Hanita’, and at 26°C in ‘Katinka’. Yield per tree and yield per unit area were highest in ‘Hanita’ and lowest in ‘Katinka’. However, the highest yield efficiency was observed in ‘Jojo’ which exhibited the lowest tree vigour. As regards physical characteristics, in general, ‘Jojo’ showed the best performance when open-pollinated or pollinated by pollen of ‘Hanita’, ‘Hanita’ under pollination by pollen of ‘Katinka’ and ‘Katinka’ under self-pollination or pollination by pollen of ‘Hanita’..

Metodološki pristup procene rizika od deponijskog požara u cilju ocene zagađenosti vazduha

Since landfill fires have not been sufficiently investigated and studied, the aim of this doctoral dissertation is to present a methodological approach to the issue. Measurements of landfill gas composition and concentrations spanning several months were performed by means of a gas analyzer at two landfills: a non-sanitary landfill "Bubanj" in Niš and a regional sanitary landfill "MuntinaPadina" in Pirot. The measurements were used to analyze fire indicators and air pollution idicators. The fire indicators were used to confirm the presence of underground fires or the possibility of outbreak, whereas the air pollution indicators were used to show whether specific parameters exceeded their limit or tolerable values. Assessment of landfill gas emission and its core components – methane, carbon dioxide, and nonmethane organic compounds was performed using the EPA LandGem mathematical model. Assessment of air pollution risk due to methane emissions and fire was performed using ALOHA software. Assessments of hazardous zones for toxicity, flammability, explosion pressure, and heat radiation were performed based on the emission of methane, which is the main component of landfill gas and is highly flammable and explosive. The results obtained in the research allow the following: identification of landfill fire hazards, landfill fire risk assessment, assessment of emissions and hazardous zones, as well as comparative analysis of two landfills. This doctoral dissertation is a result of the author’s own research and research conducted in cooperation with the doctoral supervisor. The contribution of the dissertation results pertains to the proposal of a new methodological approach of fire risk assessment and air pollution assessment, which can be applied to any sanitary landfill

Nuclear signatures in high-harmonic generation from laser-driven muonic atoms

High-harmonic generation from muonic atoms exposed to intense laser fields is considered. Our particular interest lies in effects arising from the finite nuclear mass and size. We numerically perform a fully quantum mechanical treatment of the muon-nucleus dynamics by employing modified soft-core and hard-core potentials. It is shown that the position of the high-energy cutoff of the harmonic spectrum depends on the nuclear mass, while the height of the spectral plateau is sensitive to the nuclear radius. We also demonstrate that $\gamma$-ray harmonics can be generated from muonic atoms in ultrastrong VUV fields, which have potential to induce photo-nuclear reactions.Comment: 5 pages, 3 figure