Electronic structure of periodic curved surfaces -- topological band structure

Electronic band structure for electrons bound on periodic minimal surfaces is differential-geometrically formulated and numerically calculated. We focus on minimal surfaces because they are not only mathematically elegant (with the surface characterized completely in terms of "navels") but represent the topology of real systems such as zeolites and negative-curvature fullerene. The band structure turns out to be primarily determined by the topology of the surface, i.e., how the wavefunction interferes on a multiply-connected surface, so that the bands are little affected by the way in which we confine the electrons on the surface (thin-slab limit or zero thickness from the outset). Another curiosity is that different minimal surfaces connected by the Bonnet transformation (such as Schwarz's P- and D-surfaces) possess one-to-one correspondence in their band energies at Brillouin zone boundaries.Comment: 6 pages, 8 figures, eps files will be sent on request to [email protected]

The influence of low-frequency magnetic field regions on the Saccharomyces cerevisiae respiration and growth

The influence of four low-frequency magnetic field (MF) ranges 10–300 Hz, 10–100 Hz, 10–50 Hz and 50–100 Hz in scanning regime (all frequencies from selected range were scanned during 100 s repetitively during 24 h) on baker's yeast cells Saccharomyces cerevisiae was examined by continuous measurements of cumulative O2 consumption and cumulative CO2 production over 24 h with Micro-Oxymax® respirometer. Besides respiration activity, measurements of cell growth and glucose uptake were performed as well. Statistical analysis indicated that, among all investigated low-frequency MF ranges, range from 10 Hz to 50 Hz had the greatest influence to yeast cell respiration and cell growth. More precisely, for this region, paired two sample one-tail t-test showed statistically significant differences in cumulative O2 consumption, cumulative CO2 production and S. cerevisiae cell number. Moreover samples exposed to MF range from 10 Hz to 50 Hz showed the same behavior in all five replicates: lower cumulative O2 consumption, higher cumulative CO2 production and higher cell number compared to control sample. This could be important from the application aspect, in industry (food, feed, brewery etc.) and biotechnology, because changes in cells metabolism are not caused by chemical treatment.Related to published version: [http://cherry.chem.bg.ac.rs/handle/123456789/3321

Supplementary material for the article: Lončarević, B.; Lješević, M.; Marković, M.; Anđelković, I.; Gojgić-Cvijović, G.; Jakovljević, D.; Beškoski, V. Microbial Levan and Pullulan as Potential Protective Agents for Reducing Adverse Effects of Copper on Daphnia Magna and Vibrio Fischeri. Ecotoxicology and Environmental Safety 2019, 181, 187–193. https://doi.org/10.1016/j.ecoenv.2019.06.002

Supplementary material for: [https://www.sciencedirect.com/science/article/pii/S014765131930630X?via%3Dihub]Related to published version: [http://cherry.chem.bg.ac.rs/handle/123456789/3158

Supplementary data for article: Kekez, B. D.; Gojgic-Cvijovic, G. D.; Jakovljevic, D. M.; Stefanovic Kojic, J. R.; Markovic, M. D.; Beskoski, V. P.; Vrvic, M. M. High Levan Production by Bacillus Licheniformis NS032 Using Ammonium Chloride as the Sole Nitrogen Source. Applied Biochemistry and Biotechnology 2015, 175 (6), 3068–3083. https://doi.org/10.1007/s12010-015-1475-8

Supplementary material for: [https://doi.org/10.1007/s12010-015-1475-8]Related to published version: [http://cherry.chem.bg.ac.rs/handle/123456789/1670

High-density ceramics obtained by andesite basalt sintering

In the present study, andesite basalt originated from the deposit site “Donje Jarinje”, Serbia, was examined as a potential raw material for high-density ceramics production. The production of high-density ceramics included dry milling, homogenization, cold isostatic pressing and sintering in the air. To determine the optimal processing parameters the sintering was conducted at 1040, 1050, 1060, 1070 and 1080°C, and afterwards the sintering duration was varied from 30 to 240min at the optimal sintering temperature of 1060°C. Characterization of the starting and sintered materials included the estimation of particle size distribution, density, hardness and fracture toughness complemented with X-ray diffraction, optical light microscopy, scanning electron microscopy and energy dispersive spectroscopy analysis. Phase transformations did not occur during processing in the investigated temperature range from 1040 to 1080°C. The obtained research results showed that 99.5% of relative density and the highest hardness and fracture toughness values of 6.7GPa and 2.2MPa•m1/2, respectively, were achieved for the andesite basalt sintered at 1060°C for 60min in the air. The results of the present study confirmed that the sintered andesite basalt can be used as a high-density ceramic material for various industrial applications

Promena izoprenoidne, steranske i terpanske frakcije tokom ex situ bioremedijacije mazuta na industrijskom nivou

This paper presents the results of an ex situ bioremediation of soil contaminated by mazut (heavy residual fuel oil) in the field scale (600 m(3)). The treatment-bed (thickness 0.4 m) consisted of mechanically mixed mazut-contaminated soil, softwood sawdust as an additional carbon source and crude river sand, as a bulking and porosity increasing material. The inoculation/reinoculation was conducted periodically using a biomass of a consortium of zymogenous microorganisms isolated from a bioremediation substrate. The biostimulation was performed through addition of nutritious substances (N, P and K). The aeration was improved by systematic mixing of the bioremediation system. After 50 days, the number of hydrocarbon degraders had increased a 100 fold. Based on the changes in the group composition, the average biodegradation rate during bioremediation was 24 mg kg(-1) day(-1) for the aliphatic fraction, 6 mg kg(-1) day(-1) for the aromatic fraction and 3 mg kg(-1) day(-1) for the nitrogen-sulphur-oxygen compounds (NSO)-asphaltene fraction. In the saturated hydrocarbon fraction, gas chromatography-mass spectrometry (GC-MS) in the single ion-monitoring mode (SIM) was applied to analyse isoprenoids pristane and phytane and polycyclic molecules of sterane and triterpane type. Biodegradation occurred during the bioremediation process, as well as a reduction of the relative quantities of isoprenoids, steranes, tri- and tetracyclic terpanes and pentacyclic terpanes of the hopane type.Prikazani su rezultati ex situ bioremedijacije zemljišta kontaminiranog mazutom na industrijskom nivou (600 m3). Bioremedijacioni materijal (debljine 0,4 m) se sastojao od mehanički pomešanih mazutom zagađenog zemljišta, čamove piljevine kao dodatnog izvora ugljenika i neprečišćenog rečnog peska, dodatog u cilju mešanja i povećanja poroznosti. Inokulacija/reinokulacija (bioaugmentacija) je periodično rađena sa biomasom konzorcijuma zimogenih mikrooorganizama izolovanih iz supstrata za bioremedijaciju. Biostimulacija je realizovana dodatkom hranljivih supstanci (N, P i K). Aeracija je poboljšavana sistematskim mešanjem bioremedijacionog sistema. Nakon 50 dana broj mikroorganizama koji degradiraju ugljovodonike povećan je 100 puta. Na osnovu promena u grupnom sastavu prosečna stopa biodegradacije tokom bioremedijacije je bila za alifatičnu frakciju 24 mg kg-1 po danu, za aromatičnu 6 mg kg-1 po danu i 3 mg kg-1 po danu za NSO-asfaltensku frakciju. U zasićenoj ugljovodoničnoj frakciji metodom GC-MS (SIM metod) analizirani su izoprenoidi pristan i fitan i policiklični molekuli steranskog i triterpanskog tipa. Tokom bioremedijacionog procesa došlo je do biodegradacije i smanjenja relativnih količina izoprenoida, sterana, tri- i tetracikličnih terpana i pentacikličnih terpana hopanskog tipa

Green synthesis of silver nanoparticles using Bacillus licheniformis strain

The development of eco-friendly technologies in different areas, as well as in nanotechnology, is of great importance to the expansion of the many biological applications of microrganisms. In this work, the synthesis of silver nanoparticles by the reduction of aqueous Ag+ ions using the non-pathogenic bacterial strain B. licheniformis, under mild conditions, was investigated. The synthesized nanoparticles were characterized by UV–Vis spectroscopy, scanning electron microscopy (SEM), and electron diffraction spectroscopy (EDX)

Supplementary data for the article: Kekez, B.; Gojgić-Cvijović, G.; Jakovljević, D.; Pavlović, V.; Beškoski, V.; Popović, A.; Vrvić, M. M.; Nikolić, V. Synthesis and Characterization of a New Type of Levan-Graft-Polystyrene Copolymer. Carbohydrate Polymers 2016, 154, 20–29. https://doi.org/10.1016/j.carbpol.2016.08.001

Supplementary material for: [https://doi.org/10.1016/j.carbpol.2016.08.001]Related to published version: [http://cherry.chem.bg.ac.rs/handle/123456789/2300

Supplementary data for the article: Lješević, M.; Gojgić-Cvijović, G.; Ieda, T.; Hashimoto, S.; Nakano, T.; Bulatović, S.; Ilić, M.; Beškoski, V. Biodegradation of the Aromatic Fraction from Petroleum Diesel Fuel by Oerskovia Sp. Followed by Comprehensive GC×GC-TOF MS. Journal of Hazardous Materials 2019, 363, 227–232. https://doi.org/10.1016/j.jhazmat.2018.10.005

Supplementary material for: [https://www.sciencedirect.com/science/article/pii/S0304389418308951?via%3Dihub]Related to published version: [http://cherry.chem.bg.ac.rs/handle/123456789/351]Related to accepted version: [http://cherry.chem.bg.ac.rs/handle/123456789/2800