Variations of radiographic images of dental luting cements and composite posts depending on their compostion and radiographic system used

У складу са ѕахтевима које прописује међународна организација за стандардизацију (ISO) рендгенконтрастност денталних цемената и денталних кочића треба да буде већа од рендгенконтрастности исте дебљине алуминијума. Циљеви спроведених in vitro истраживања били су да се: утврди рендгенконтрастност различитих врста денталних цемената на дигиталној радиографији уз употребу ЦЦД дигиталног сензора, испита капацитет различитих радиографских метода да се испита рендгенконтрастност материјала зависно контрастног средства присутног у материјалу, установи рендгенконтрастност различитих врста денталних кочића и њихова минимална клинички прихватљива рендгенконтрасност и да се испитају могућности конвенционалне и дигиталне радиографије у дијагностиковању заосталог вишка цемента на абатменту након цементирања протетских рестаурација. Материјали и методе. Пет категорија цемената за цементирање протетских надокнада је коришћено: два цинк фосфатна цемента (Cegal N и Harvard Zinc Phosphate), два цинк поликарбоксилатна цемента (Harvard Polycarboxylate и Hoffmann’s Carboxylate), три глас јономерна цемента (Ketac Cem Easymix, Ketac Cem Radiopaque и Fuji I), један смолом модификовани глас јономерни цемент (Rely X Luting) и пет композитних цемената (Multilink Automix, Variolink II, Speed CEM, Rely X Unicem Automix и Variolink Veneer). Узорци глеђи и дентина су коришћени као контрола. По пет узорака сваког материјала пречника 8 mm и дебљине 1 mm је припремљено и радиографисано заједно са узорцима хуманих зубних ткива и алуминијумским еталоном уз помоћ Trophy RVG дигиталног сензора (Trophy Radiology, Cedex, France). Рендгенконтрастност материјала је изражавана у еквивалентној дебљини алуминијума и анализирана уз помоћ ANOVA и Тukey теста (P<0,05)...Objectives. According to the International Standard Organization (ISO), the radiopacity of luting cements and dental posts should be equal to or greater than that of aluminum. The aims of these in vitro studies were: to determine the radiopacity of 13 commercially available dental luting cements and compare it with that of human enamel and dentin, to investigate the capacity of various radiopacifying agents to produce the difference in radiopacity on film and a CCD - based digital sensor, to evaluate the radiopacity of seven commercially available dental posts and determine the minimum radiopacity value necessitated for their clinical evaluation and to determine the threshold radiopacity value for detection of small thicknesses of dental luting cements in adjacent to implant abutment. Materials and Methods. Five classes of luting cements were evaluated: zinc phosphate (Cegal N and Harvard Zinc Phosphate), zinc polycarboxylate (Harvard Polycarboxylate and Hoffmann’s Carboxylate), glass ionomers (Ketac Cem Easymix, Ketac Cem Radiopaque and Fuji I), resin-modified glass ionomer (Rely X Luting), and resin cements (Multilink Automix, Variolink II, Speed CEM, Rely X Unicem Automix and Variolink Veneer). Teeth slices served as controls. Five specimens of each material measuring 8 mm in diameter and 1 mm thick were prepared and radiographed alongside tooth slices and an aluminum stepwedge using a Trophy Radiovisiography (RVG) sensor (Trophy Radiology, Cedex, France). The radiopacity values were expressed in mm Al and analyzed by the ANOVA and Tukey tests (P < 0,05). For determination of radiographic system capacity to detect material's radiopacity depending on the radiopacifier present within experimental cements were formulated by mixing metacrylate with the following radiopacifying agents: zinc oxide (ZnO), zirconium oxide (ZrO2), titanium dioxide (TiO2), barium sulphate (BaSO4), iodoform (CHI3), bismuth oxide (Bi2O3) and ytterbium trifluoride (YbF3). Five specimens of each material were radiographed alongside an aluminum stepwedge on Е speed film (Eastman Kodak Company, Rochester, NY) and a CCD - based digital sensor (Trophy Radiology). Radiopacity values were calculated by converting the radiographic densities of the specimens expressed as a mean optical densities or mean grey scale values into equivalent thickness of aluminum..

Beyond Diophantine Wannier diagrams: Gap labelling for Bloch-Landau Hamiltonians

It is well known that, given a $2d$ purely magnetic Landau Hamiltonian with a constant magnetic field $b$ which generates a magnetic flux $\varphi$ per unit area, then any spectral island $\sigma_b$ consisting of $M$ infinitely degenerate Landau levels carries an integrated density of states $\mathcal{I}_b=M \varphi$. Wannier later discovered a similar Diophantine relation expressing the integrated density of states of a gapped group of bands of the Hofstadter Hamiltonian as a linear function of the magnetic field flux with integer slope. We extend this result to a gap labelling theorem for any $2d$ Bloch-Landau operator $H_b$ which also has a bounded $\mathbb{Z}^2$-periodic electric potential. Assume that $H_b$ has a spectral island $\sigma_b$ which remains isolated from the rest of the spectrum as long as $\varphi$ lies in a compact interval $[\varphi_1,\varphi_2]$. Then $\mathcal{I}_b=c_0+c_1\varphi$ on such intervals, where the constant $c_0\in \mathbb{Q}$ while $c_1\in \mathbb{Z}$. The integer $c_1$ is the Chern character of the spectral projection onto the spectral island $\sigma_b$. This result also implies that the Fermi projection on $\sigma_b$, albeit continuous in $b$ in the strong topology, is nowhere continuous in the norm topology if either $c_1\ne0$ or $c_1=0$ and $\varphi$ is rational. Our proofs, otherwise elementary, do not use non-commutative geometry but are based on gauge covariant magnetic perturbation theory which we briefly review for the sake of the reader. Moreover, our method allows us to extend the analysis to certain non-covariant systems having slowly varying magnetic fields.Comment: 17 pages, no figure

Diesel production by fast pyrolysis of miscanthus giganteus, well-to-pump analysis using the greet model

In this paper "well-to-pump" environmental analysis of pyrolytic diesel from Miscanthus gigantheus is performed. The average annual yield of Miscanthus from III-V year of cultivation on 1 ha of chernozem soil in Serbia (23.5 t) is considered as an input for the process. Two pyrolytic diesel pathways are considered: distributed pyrolytic pathway with external hydrogen production (from natural gas) and integrated pyrolytic pathway with internal hydrogen production (from pyrolytic oil). and are compared to a conventionally produced diesel pathway. The results of the analysis reveal that integrated-internal pyrolytic diesel pathway has lowest resources consumption and lowest pollutant emissions. Compared to conventionally produced diesel, integrated-internal pyrolysis pathway consumes 80% less of fossil fuels, and 92% more of renewables, has 90% lower global warming potential, 30% lower terrestrial acidification potential but 38% higher particulate matter formation potential. Compared to the distributed-external pathway, 88% less fossil fuels, and 36% less renewables are consumed in the integrated-internal pathway, global warming potential is 97% lower, terrestrial acidification is 20% lower, and particulate matter formation is 49% lower. Nevertheless, this pathway has high coal and hydroelectrical power consumption due to electricity production and high emissions of particulate matter, CO2, SOx, and N2O. Another drawback of this production pathway is the low yield of diesel obtained (38% lower than in distributed-external pathway). With this regard, it is still hard to designate production of diesel from fast pyrolysis of Miscanthus as a more environmentally friendly replacement of the conventional production diesel pathway

Supplementary material for the article: Malenov, D. P.; Antonijević, I. S.; Hall, M. B.; Zarić, S. D. Stacking of Cyclopentadienyl Organometallic Sandwich and Half-Sandwich Compounds. Strong Interactions of Sandwiches at Large Offsets. CrystEngComm 2018, 20 (31), 4506–4514. https://doi.org/10.1039/c8ce00597d

Supplementary material for: [https://doi.org/10.1039/c8ce00597d]Related to published version: [http://cherry.chem.bg.ac.rs/handle/123456789/2202

Supplementary data for the article: Antonijević, I. S.; Janjić, G. V.; Milčić, M. K.; Zarić, S. D. Preferred Geometries and Energies of Sulfur-Sulfur Interactions in Crystal Structures. Crystal Growth and Design 2016, 16 (2), 632–639. https://doi.org/10.1021/acs.cgd.5b01058

Supplementary material for: [https://doi.org/10.1021/acs.cgd.5b01058]Related to published version: [http://cherry.chem.bg.ac.rs/handle/123456789/2042]Related to accepted version: [http://cherry.chem.bg.ac.rs/handle/123456789/3596

Investigation of IR-Spectra of N-Benzoyl- N-phenylhydroxylamine in Carbon Tetrachloride

Spectra of carbon\u27 tetrachloride solutions of N-benzoyl-N-phenylhydroxylamine in concentrations between 1X10-• a nd 25 X 10-• M, in the spectral range from 2800 cm-1 to 4000 cm-1 were measured. Appearance of the absorption band at 3070 cm- 1 is ascribed to C-H stretching, and the band at 3250 cm-1 to H ... 0-H bond. The validity of Beer\u27s law for the band at 3250 cm-1 and the fact that no bands between 3400 and 4000 cm-1 were detected indicate the presence of an intramolecular H bond

Raspodela olova u vodi i njegova asocijacija sa elementima u sedimentu jezera "Barje" (Leskovac, Jugoslavija)

The lead concentrations in the water of the "Barje" lake are presented for the years 1995 to 1998. Sequential extraction was applied to estimate the chemical association of lead in the sediments of the "Barje" lake. Several lead fractions showed highly significant correlations with the corresponding substrate (step II: Mn-oxyhydroxides; step III: Fe-oxyhydroxides) suggesting that lead carbonates were incorporated with amorphous iron and manganese hydroxides. An explanation for this relation can be in the same anthropogenic source of these elements.Predstavljena je koncentracija olova za jezero "Barje" od 1995 do 1998. godine. Sekvenciona ekstrakcija je primenjena za proučavanje hemijskih asocijacija olova u sedimentima jezera "Barje". Visoko signifikantne korelacije pojedinih frakcija olova sa odgovarajućim supstratima (druga faza: Mn oksihidroksidima; treća faza: Fe oksihidroksidima) pokazuje da su olovo-karbonati inkorporirani sa amorfnim hidroksidima gvožđa i mangana. Objašnjenje se može potražiti u istom antropogenijskom izvoru

Theoretical Foundation and Actuality of the Concept Education through Art

This paper is on the relation between art and education through the concept Education through Art, from the perspective of progressive pedagogy. Theoretical foundation is analysed through the theories of John Dewey and Herbert Read who stressed that art should be experienced, not only because of its prefect value, but because of its pedagogical potential (for the purpose of recreating and reconstructing experience). Elliot Eisner contribution is also analysed, who discussing the significance of art, points out at the cognitive aspect of art in education. With his work, pedagogy gets steady alternative model in relation to the contemporary school which is intellectually oriented and in which pedagogical work in school is focused on verbal and mathematical proficiencies. Progressive pedagogy opposes traditional formalism in education, which is organised in advance by the subject syllabi, and teaching to the test. It promotes desirable interdisciplinary organisation of teaching, with the cross curricular activities, transforming the learning environment in this way. In the paper, we discussed implications for the praxis of theoretical concept, which directs the work at school towards the whole development of personality and it affirms realisation of creative activities through play and research integrating art in the process of learning

Supplementary data for the article: Antonijević, I. S.; Janjić, G. V.; Milčić, M. K.; Zarić, S. D. Preferred Geometries and Energies of Sulfur-Sulfur Interactions in Crystal Structures. Crystal Growth and Design 2016, 16 (2), 632–639. https://doi.org/10.1021/acs.cgd.5b01058

Supplementary material for: [https://doi.org/10.1021/acs.cgd.5b01058]Related to published version: [http://cherry.chem.bg.ac.rs/handle/123456789/2042]Related to accepted version: [http://cherry.chem.bg.ac.rs/handle/123456789/3596

Supplementary data for the article: Andrić, J. M.; Antonijević, I. S.; Janjić, G. V.; Zarić, S. D. Influence of Hydrogen Bonds on Edge-to-Face Interactions between Pyridine Molecules. J Mol Model 2018, 24 (3), 60. https://doi.org/10.1007/s00894-017-3570-y

Supplementary material for: [https://doi.org/10.1007/s00894-017-3570-y]Related to published version: [http://cherry.chem.bg.ac.rs/handle/123456789/2103