Properties of TaSiN thin films deposited by reactive radio frequency magnetron sputtering

TaSiN is a promising material for application as electrically conductive diffusion barrier for the integration of high permittivity perovskite materials in integrated circuits. TaSiN thin films were deposited by reactive radio frequency magnetron sputtering using TaSi and TaSi_2.7 targets in an Ar/N₂ atmosphere. The sputter power was varied in order to achieve different TaSiN compositions. The stoichiometry of as-deposited films was estimated using Rutherford backscattering spectroscopy. The as-deposited TaSiN thin films are amorphous. Their crystallization temperature is above 700 °C and increases with higher nitrogen content. They have metallic conduction and ohmic behavior. The resistivity of as deposited films is in the range from 10^− 6 Ω m up to 10^− 3 Ω m and increases with nitrogen content. It was found that p⁺⁺-Si/Ta₂₁Si₅₇N₂₁ develops unacceptable high contact resistance. Introducing an intermediate Pt layer the stack p⁺⁺-Si/Pt/Ta₂₁Si₅₇N₂₁ had a good conductive properties and good thermal stability at 700 °C.     

Chemical solution method for fabrication of nanocrystalline iron(III) oxide thin films

A chemical solution technique for preparation of nanocrystalline iron(III) oxide thin films is developed. The deposition process is essentially based on the thermal decomposition of urea. The as-deposited and post-deposition heat-treated materials were characterized by X-ray analysis and Fourier transform infrared (FTIR) spectroscopy. Basic optical and electrical investigations were also performed. X-ray analysis confirmed that post-deposition heat-treated material is nontextured -iron(III) oxide, with an average crystal size of 22 nm. The optical investigations show that the absorption of films (as-deposited and post-deposition treated) gradually decreases with an increase of the wavelength in the 390–820 nm region. The optical band gap for the as-deposited and post-deposition heat-treated films was determined to be 3.2 eV and 2.0 eV, respectively. The obtained -Fe₂O₃ thin films exhibit a rather high resistivity at room temperature. However, our preliminary qualitative investigations have shown that the room temperature resistivity of -Fe₂O₃ thin films is highly sensitive to moisture, indicating their potential applicability in moisture sensing systems.     

Rapid Determination of Trace Elements in Macedonian Grape Brandies for Their Characterization and Safety Evaluation

A graphite furnace atomic absorption spectrometry (GFAAS) was used for determination of trace elements (Cd, Cr, Cu, Fe, Mn, Ni, Pb, and Zn) in “rakija” samples, a grape brandy traditionally produced in Republic of Macedonia by distillation of grape pomace or wine, for characterization and safety evaluation. Cd, Pb, Cr, and Ni were determined directly, while Cu, Fe, Mn, and Zn were quantified after appropriate dilution. The calibration curves of all elements were linear with correlation coefficients (R ²) ranging from 0.9995 to 0.9998. The accuracy of the method was checked with a standard addition method showing good repeatability and reproducibility (relative standard deviation (RSD) <10 %). Relationship between several metal concentrations (Cu, Fe, Mn, Zn) in brandies and distillation system (homemade/industrial) on one side and aging mode (oak barrels/oak chips) on the other side were demonstrated. Two homemade brandies showed Cu, Fe, and Zn concentrations higher than industrial distillates and thus were found to be not safe for consumption because of Cu and Zn over the maximum allowed values. For the industrially produced brandies, Mn was identified to be a suitable marker related to aging with oak chips regardless variety, while Cu a marker for the influence of oak chip type. Principal component analysis applied on the content of elements clearly showed a good separation in terms of distillation and aging method.     

Structure study of Bi4Ti3O12 produced via mechanochemically assisted synthesis

Nanosized bismuth titanate was prepared via high-energy ball milling process through mechanically assisted synthesis directly from their oxide mixture of Bi₂O₃ and TiO₂. Only Bi₄Ti₃O₁₂ phase was formed after 3 h of milling time. The excess of 3 wt% Bi₂O₃ added in the initial mixture before milling does not improve significantly the formation of Bi₄Ti₃O₁₂ phase comparing to stoichiometric mixture. The formed phase was amorphized independently of the milling time. The Rietveld analysis was adopted to determine the crystal structure symmetry, amount of amorphous phase, crystallite size and microstrains. With increasing the milling time from 3 to 12 h, the particle size of formed Bi₄Ti₃O₁₂ did not reduced significantly. That was confirmed by SEM and TEM analysis. The particle size was less than 20 nm and show strong tendency to agglomeration. The electron diffraction pattern indicates that Bi₄Ti₃O₁₂ crystalline powder is embedded in an amorphous phase of bismuth titanate. Phase composition and atom ratio in BIT ceramics were determined by X-ray diffraction and EDS analysis.     

Evaluation of Variation in Protein Composition on Solubility,Emulsifying and Gelling Properties of Soybean Genotypes Synthesizing β' Subunit

The effects of subunit composition of two major proteins of soybean: glycinin (11S) and β‐conglycinin (7S) in nine different genotypes, on solubility and emulsifying and gelling properties at different pH (3, 5, 6, and 8) were examined. High‐protein genotypes (more than 40%) contained low amounts of the β′ subunit. The main factors influencing solubility at pH 6 were the content of α′, α (r = 0.89 and r = 0.91 at P < 0.05, respectively) and β′ subunit contents (r = ?0.71 at P < 0.05) of β‐conglycinin, while at pH 3 acidic subunits in glycinin had a positive correlation with solubility (r = 0.69 at P < 0.05). Emulsion activity at pH 6 was higher for genotypes synthesizing β′ subunit (r = 0.57 at P < 0.05). Genotypes synthesizing higher amounts of α′ and α subunit had higher emulsion stability at pH 6 (r = 0.85 and r = 0.92 at P < 0.05, respectively) and pH 8 (r = 0.91 and r = 0.97 at P < 0.05, respectively). The rheological measurements showed that genotypes with 11S/7S ratio higher than 2.2 formed gels with enhanced storage moduli. This influence was largely due to the high content of SH groups in glycinin acidic polypeptides resulting in stabilization of gels via disulfide bonding. Gels prepared from genotypes containing higher amounts of β′ subunit of β‐conglycinin exhibited reduced elastic properties. Genotypes showing better solubility also had higher emulsion stability, but formed weaker gels and had lower emulsion activity near neutral pH.     

Fusarium mycotoxins in wheat samples harvested in Serbia: A preliminary survey

The objective of this study was to determine the occurrence of trichothecenes of both the A-type and B-type, masked mycotoxin derived from DON - deoxynivalenol-3-glucoside (DON-3-Glc), 3- and 15-acetyldeoxynivalenol (ADONs), fusarenon-X (FUS-X) and nivalenol (NIV)) as well as zearalenone (ZON) in winter wheat. Total of 54 samples were collected during the harvest of 2007 representing the most important Serbian wheat-growing regions. The samples were prepared by one-step simple method and analyzed by high performance liquid chromatography coupled to tandem mass spectrometry (LC–MS/MS). The obtained recoveries proved that the used method could be successfully applied for multi-component analysis of Fusarium mycotoxins. DON, DON-3-Glc and HT-2 contents were detected approximately in 28%, 13% and 6% of the total number of samples, respectively. The amount of these toxins ranged from 17 μg/kg for DON-3-Glc to 309 μg/kg for DON. ADONs, FUS-X, NIV, T-2 toxin as well as ZON were below the limit of detection. Different susceptibility of wheat cultivars towards detected mycotoxins was observed. The results were compared to the EC Regulative and with available the literature data concerning the neighboring countries. This is first report on the simultaneous presence of 8 Fusarium mycotoxins in the wheat cultivated in the Balkan Countries region.     

On the tungsten carbide synthesis for PEM fuel cell application – Problems,challenges and advantages

Fuel cell application of tungsten carbide is revisited starting with four different tungsten carbide precursors used for high temperature synthesis. It was shown that the final products greatly depend on the nature of the precursor. Using tungsten peroxide/2-propanol derived precursor almost pure WC was obtained which was subjected to further electrochemical investigation. It was shown that it is necessary to decorate WC with Pt nanoparticles in order to obtain satisfactory fuel cell performance, but catalytic activity of Pt/WC anode catalyst is not expected to overcome the activity of Pt/C. It is argued that new synthetic routes for the preparation of WC should be directed towards obtaining highly dispersed WC, that is, WC with high external surface area available for Pt deposition, rather than high specific surface area WC with large contribution of micropores having no importance when it comes to the use of WC as a catalyst support. The true benefit of the use of WC as catalyst support is found in increased CO tolerance/CO oxidation activity of WC-supported Pt catalysts. Qualitative mechanistic view on increased CO oxidation activity of Pt/WC is offered.     

Fruit Phenolic Composition of Different Elderberry Species and Hybrids

The aim of this study was to investigate a detailed composition and content of phenolic compounds in fruits of 4 elderberry species (Sambucus nigra, S. cerulea, S. ebulus, and S racemosa) and 8 interspecific hybrids. Hydroxycinnamic acids (HCAs) represented the major share of phenolics in analyzed elderberries; caffeoylquinic and p‐coumaroylquinic acids were most abundant. Flavanols (catechin, epicatechin, and different procyanidins) were the second major phenolic group detected in range from 2% to 30% of total analyzed phenolics. From the group of flavonols, 13 different quercetin glycosides, 7 kaempferol glycosides, and 8 isorhamnetin glycosides have been quantified. Rutin was the major flavonol in all studied genotypes. S. ebulus was characterized by the highest level of total HCAs, catechin, epicatechin, and most flavonols. Some elderberry hybrids, for example JA × RAC, CER × NI, and JA × (JA × NI), are perspective for further studies because they have high content of phenolic compounds. The results of research could contribute to breed cultivars, which may prove interesting for food‐processing industries.