Geopolymer/CeO2 as Solid Electrolyte for IT-SOFC

As a material for application in the life sciences, a new composite material, geopolymer/CeO2 (GP_CeO2), was synthesized as a potential low-cost solid electrolyte for application in solid oxide fuel cells operating in intermediate temperature (IT-SOFC). The new materials were obtained from alkali-activated metakaolin (calcined clay) in the presence of CeO2 powders (x = 10%). Besides the commercial CeO2 powder, as a source of ceria, two differently synthesized CeO2 powders also were used: CeO2 synthesized by modified glycine nitrate procedure (MGNP) and self-propagating reaction at room temperature (SPRT). The structural, morphological, and electrical properties of pure and GP_CeO2-type samples were investigated by X-ray powder diffraction (XRPD), Fourier transform infrared (FTIR), BET, differential thermal and thermogravimetric analysis (DTA/TGA), scanning electron microscopy (FE-SEM), energy dispersive spectrometer (EDS), and method complex impedance (EIS). XRPD and matrix-assisted laser desorption and ionization time-of-flight (MALDI-TOF) analysis confirmed the formation of solid phase CeO2. The BET, DTA/TGA, FE-SEM, and EDS results indicated that particles of CeO2 were stabile interconnected and form a continuous conductive path, which was confirmed by the EIS method. The highest conductivity of 1.86 × 10−2 Ω−1 cm−1 was obtained for the sample GP_CeO2_MGNP at 700 °C. The corresponding value of activation energy for conductivity was 0.26 eV in the temperature range 500–700 °C

Supplementary data for article : Lozo, J.; Mirkovic, N.; O’Connor, P. M.; Malesevic, M.; Miljkovic, M.; Polović, N.; Jovcic, B.; Cotter, P. D.; Kojić, M. O. Lactolisterin BU, a Novel Class II Broad-Spectrum Bacteriocin from Lactococcus Lactis Subsp Lactis Bv. Diacetylactis BGBU1-4. Applied and Environmental Microbiology 2017, 83 (21). https://doi.org/10.1128/AEM.01519-17

Supplementary material for: [ https://doi.org/10.1128/AEM.01519-17]Related to published version: [http://cherry.chem.bg.ac.rs/handle/123456789/2541

Carbon dioxide activation of the plane tree seeds derived bio-char: Kinetic properties and application

Goal of this work is to establish technical feasibility and fundamentals of producing activated carbon from plane tree seeds biomass for porous materials derivation. Bio-chars produced via carbonization from plane tree seeds precursor were activated in CO2 at 750 and 850?C, during various residence times. Their surface area and porosity were characterized by N2 adsorption at 77 K. Surface areas of activated carbons can be correlated with kinetics mechanism and activation energy magnitudes of oxidation reaction by CO2, which are closely related to applied activation temperature. Result showed that high temperature activated carbon had higher gas adsorption as compared to activated carbon obtained from lower temperature during two-hour residence time. Breakthrough behavior was detected at 850?C where surface reactions dominate, and it is characterized by autocatalytic kinetic model under designed conditions. Both, temperature and CO2 concentration in vicinity of solid surface effect on breakthrough time of adsorbent. Derived bio-chars are converted into high quality activated carbons, with surface area of 776.55 m2/g, where micro-pores with pore diameters less than 2 nm prevail. Produced activated carbons have properties comparable with commercially available activated carbons, which can be successfully used for removal of harmful gaseous pollutants toward air purification

Brevibacillus laterosporus strains BGSP7, BGSP9 and BGSP11 isolated from silage produce broad spectrum multi-antimicrobials

Bacteria active against multi-drug resistant pathogens, isolated by direct selection of colonies from clover silage samples, produce zones of inhibition against two Gram-negative (Klebsiella pneumoniae Ni9 and Pseudomonas aeruginosa MMA83) and two Gram-positive (Staphylococcus aureus ATCC25923 and Listeria monocytogenes ATCC19111) pathogens. Isolates BGSP7, BGSP9, BGSP11 and BGSP12 produced the largest zones of inhibition against all four pathogens when grown in LB broth with aeration at 37 degrees C. Isolates BGSP7, BGSP9, BGSP11 and BGSP12 were identified as Brevibacillus laterosporus and pulsed field gel electrophoresis and extracellular protein profiles showed that three different strains (BGSP7, BGSP9 and BGSP11) were isolated. A semi-native SDS-PAGE (sodium dodecyl sulphate-polyacrylamide gel electrophoresis) gel overlay assay showed that BGSP7 and BGSP9 produce small antimicrobial molecules of about 1.5 kDa, while BGSP11 produces antimicrobial molecules of 1.5 and 6 kDa active against S. aureus ATCC25923. Amino acid analysis of two antimicrobial molecules (1583.73 Da; from BGSP7 and 1556.31 Da; from BGSP11) revealed that they have a similar composition and differ only by virtue of the presence of a methionine which is present only in BGSP11 molecule. Genome sequencing of the three isolates revealed the presence of gene clusters associated with the production of non-ribosomally synthesized peptides (brevibacillin, bogorol, gramicidin S, plipastatin and tyrocin) and bacteriocins (laterosporulin, a lactococcin 972-like bacteriocin, as well as putative linocin M18, sactipeptide, UviB and lantipeptide-like molecules). Ultimately, the purification of a number of antimicrobial molecules from each isolate suggests that they can be considered as potent biocontrol strains that produce an arsenal of antimicrobial molecules active against Gram-positive and Gram-negative multi-resistant pathogens, fungi and insects

Supplementary data for article : Lozo, J.; Mirkovic, N.; O’Connor, P. M.; Malesevic, M.; Miljkovic, M.; Polović, N.; Jovcic, B.; Cotter, P. D.; Kojić, M. O. Lactolisterin BU, a Novel Class II Broad-Spectrum Bacteriocin from Lactococcus Lactis Subsp Lactis Bv. Diacetylactis BGBU1-4. Applied and Environmental Microbiology 2017, 83 (21). https://doi.org/10.1128/AEM.01519-17

Supplementary material for: [ https://doi.org/10.1128/AEM.01519-17]Related to published version: [http://cherry.chem.bg.ac.rs/handle/123456789/2541

Lead Free Polymer Composites for Radiation Shielding

Radiation shielding is a crucial precautionary measure in decreasing the dose of exposure medical personnel experience. The physical dimensions of these shields, specifically thickness and shape, are dependent on the type of radiation, energy and specific radioactivity. Currently, the most common radiation shielding equipment is made of lead, tungsten or uranium. Although these heavy metals have favorable shielding properties against ionizing radiation, protective garments such as lead aprons are heavy to wear and can pose significant health risks. Taking this into account, the primary goal of this study is to understand the radiation shielding properties of lead-free polymer geopolymer-polyurethane based composites. The geopolymer was synthesized using an 80%-20% mixture of fly ash and a bio-polyol substrate which was subsequently homogenized using MDI44. As a result, 6 samples of the geopolymer-polyurethane based composites were fabricated of which 5 were 90%-10% compositions between the mixture and varying concentrations of BaSO4 and Bi2O3 respectively. The last sample consisted of the pure fly ash/bio-polyol mixture. XRF and ICP analysis was used to chemically characterize the fly ash. The composite structures were analyzed using XRD, while the microstructural morphology was investigated using SEM techniques. Utilizing an energy-dispersive x-ray spectrometer (EDS), elemental abundance and agglomerating behavior was analyzed for each composite variant. The X-ray attenuation measurements pointed out that the obtained composites have the potential for a design of lead-free protective clothing against X-ray shielding in medical applications

Evaluation of the limb symmetry index

The main objective of present study was to evaluate inter-rater reliability and concurrent validity of Side Hop Test stopwatch vs. force plates timing, and to determine the number of sessions and trials required to minimize the effects of learning on Side Hop Test total time and limb symmetry index. Fifteen healthy male physical education students (mean ± SD: age, 23 ± 3 yearsheight, 181 ± 9 cmand weight 72 ± 6 kg) participated. Side Hop Test total time (stopwatch and force plates) of left and right leg, and limb symmetry index (force plates) were obtained over seven sessions conducted 5–7 days apart. Time recordings of two raters were similar (t = −0.56, p > 0.05) with high reliability (all ICC >0.99 and CV% 0.05for rater 1 and 2, respectively). Total time improved across the Sessions (F = 25.87, p 0.05, ω$^2$ = 0.001). Limb symmetry index ranged from 0.999 to 1.055 across all sessions and trials (all p > 0.05 and ω$^2$ < 0.00). Due to low coefficient of correlation, high interclass correlation coefficient, and the lack in heteroscedasticity, stopwatch measurements are valid to measure total time in the Side Hop Test. Moreover, stopwatch measurements could be reliably used to measure total time in the Side Hop Test, while the test could be administrated with only one experienced rater. Unlike total times, findings on limb symmetry index suggest it could be reliably assessed after seven familiarization sessions

C-protein α-antigen modulates the lantibiotic thusin resistance in Streptococcus agalactiae

Screening for producers of potent antimicrobial peptides, resulted in the isolation of Bacillus cereus BGNM1 with strong antimicrobial activity against Listeria monocytogenes. Genome sequence analysis revealed that BGNM1 contains the gene cluster associated with the production of the lantibiotic, thusin, previously identified in B. thuringiensis. Purification of the antimicrobial activity confirmed that strain BGMN1 produces thusin. Both thusin sensitive and resistant strains were detected among clinical isolates of Streptococcus agalactiae. Random mutagenesis of a thusin sensitive strain, S. agalactiae B782, was performed in an attempt to identify the receptor protein for thusin. Three independent thusin resistant mutants were selected and their complete genomes sequenced. Comparative sequence analysis of these mutants with the WT strain revealed that duplication of a region encoding a 79 amino acids repeat in a C-protein α-antigen was a common difference, suggesting it to be responsible for increased resistance to thusin. Since induced thusin resistant mutants showed higher level of resistance than the naturally resistant B761 strain, complete genome sequencing of strain B761 was performed to check the integrity of the C-protein α-antigen-encoding gene. This analysis revealed that this gene is deleted in B761, providing further evidence that this protein promotes interaction of the thusin with receptor

Exploring the antibacterial potential of Lactococcus lactis subsp. lactis bv. diacetylactis BGBU1-4 by genome mining, bacteriocin gene overexpression, and chemical protein synthesis of lactolisterin BU variants

Lactic acid bacterium Lactococcus lactis BGBU1-4 produces 43 amino acids (aa) long bacteriocin, lactolisterin BU (LBU), a 5.161 kDa peptide with potent antibacterial activity against many Gram-positive pathogens. In addition, BGBU1-4 produces an additional unknown product of 3.642 kDa with antibacterial activity. Here, we determined that the significant amount of naturally produced LBU breaks down to create a 3.642 kDa truncated form of LBU bacteriocin consisting of 31 N-terminal aa (LBU1-31) that exhibits 12.5% the antibacterial activity of the full-length LBU. We showed that chemically synthesized LBU is stable and 50% less active than native LBU, and so we used the synthetic peptides of LBU and its variants to further study their activities and antibacterial potential. Deletion analysis of LBU revealed that the 24 N-terminal aa of LBU (LBU1-24) are responsible for antibacterial activity, while downstream aa (25–43) determine the species-specific effectiveness of LBU. Although LBU1-31 contains aa 1–24, the truncation at position 31 is predicted to change the structure within aa 15–31 and might impact on antibacterial activity. Intriguingly, whole genome sequencing and genome mining established that BGBU1-4 is abundant in genes that encode potential antibacterials, but produces LBU and its breakdown product LBU1-31 exclusively

Roles of Junglas nigra husk extract microelements as radioprotectors: an in vivo model using 99mTc-radiopharmaceuticals

The aim of this work was to analyze the multi-elemental composition of the extracts of J. nigra husk, with an assessment of the possible influence of their microelements on biochemical, toxicological and radioprotective effects of in rats exposed to radiation from 99mTc-radiopharmaceuticals. The elements in extract were quantified: microelements (Zn>Al>Se>Cu>Sr>Cr>Ni>Mn>Ba>I>V) and toxic-elements (Pb>Hg>Cd>As). The use of extract in rats showed no clinical evidence of toxicity in terms of biochemical parameters. The results showed significant alteration in the organs accumulation of 99mTc-radiopharmaceuticals. The results showed that extract of J. nigra husk may act as a potential radioprotector of organ system