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Investigating NTC thermistor, ferroelectric and electric properties of Fe2TiO5
Get PDFPure phase orthorhombic pseudobrookite (Fe2TiO5) was synthesized using a
modified sol-gel method. Bulk samples were obtained by uniaxial pressing of the
obtained powder into compacts sintered at 900 oC for 2 h. A noticeable NTC
thermistor effect was noted with a B20/55 value of 5747 K and high resistivity of 45
Mcm at 25 oC. A non-linear current-voltage characteristic was observed in the
voltage range (0.2–1100 V) at room temperature (25 oC). Non-saturated (lossy) P-E
loops were obtained at both measured frequencies (100 Hz and 1 kHz) more
expressed for the higher measured frequency, with the maximal polarization of
0.291 mikroC/cm2 and remanent polarization of 0.123 mikroC/cm2 for 20 kV/cm2 and 1 kHz.
Complex impedance measured in the temperature range 20–330 oC enabled analysis
of the contribution of grain boundary and grains to the conduction mechanism. Bulk
conductivity data determined in this temperature range was analyzed using
Jonscher’s universal dielectric response model and showed that the conduction
process followed the nearest neighbor hopping conduction mechanism
Sugars and Organic Acids in 25 Strawberry Cultivars: Qualitative and Quantitative Evaluation
Get PDF(1) The nutritional quality of strawberry (Fragaria × ananassa Duch) fruits, among others, is largely maintained by the presence of soluble sugars and organic acids. As the primary products of photosynthesis, they are energy depots in plants, necessary for the construction of cell constituents, but also serve as precursors of aromatic compounds and signaling molecules. (2) In this study, fruits of 25 strawberry cultivars were qualitatively and quantitatively characterized concerning individual sugars and organic acids by HPLC, FT-ICR-MS, and MS imaging analysis. In addition, the total quality index (TQI), as a novel mathematical model, was used to compare all individual parameters evaluated to obtain a quantitative single score, as an indicator of overall fruit quality. (3) Regardless of a large number of cultivars and monitored parameters that were studded, several cultivars stood out in terms of selected primary metabolites, such as ‘Rumba’, ‘Jeny’, and ‘Sandra’, while the latter had the best TQI score. (4) Intercultivar variations in sugars and organic acids profiles, along with other bioactive compounds, should be considered for selection of promising cultivars with improved naturally occurring nutraceutical traits. Besides the search for a pleasant taste, increased awareness of healthy nutrition resulted in heightening consumer demand for high-quality fruit
The paleokarst origin of the carbonate “Ropočevo breccia” and a closing Neotethys: regional geological constraints on the Vardar zone s.s. (Belgrade area, Central Serbia)
No full textAn extremely rare carbonate breccia in the Ropočevo area (southern outskirts of Belgrade, near Avala Mt., Central Serbia), provides a clue on the probable mechanism of both its paleokarstification and a tectonic relationship with lithospheric-scale compressional events which have occurred along the latest Jurassic Neotethyan Vardar Ocean margin. Outcropping as a well-lithified block, “Ropočevo breccia” exposes an abundance of large angular, boulder-size clasts composed of partially recrystallized limestone. It has been used for decorative purposes in the near past. The famous decorative stone “Ropočevo breccia” represents an isolated olistolith-like carbonate block engulfed by the Upper Cretaceous Vardar Zone s.s. turbidites. In the Ropočevo area, two penecontemporaneous turbidite systems are separated by the Alpine west-vergent thrust. However, the “Ropočevo breccia” is related to neither the underlying Lower Cretaceous- nor the overlaying Upper Cretaceous turbidites. Such a regional-geological relationship indicates a presence of a pre-Upper Cretaceous tectonic exhumation event, followed by a rather short subaerial paleokarst episode. The suggested paleokarst episode is characterized by the absence of progressive abrasion and of visible roundness of the considerably large carbonate clasts. The regional geological constraints on the investigated “Ropočevo breccia” show that the isolated “olistolith” is a breccia formed by the end of Berriasian, amalgamated from the clasts formed in a collapsed cave rooted within the primary carbonate sequence of the (latest Tithonian-)Berriasian age. The proposed interpretation is in line with the “Basal unit” of the Lower Cretaceous “Paraflysch” belonging to a well-hidden basal sequence of the East Vardar Zone of Central Serbia. Moreover, the available aeromagnetic data of the Avala Mt./Ripanj–Ropočevo–Kosmaj Mt. sector, corroborate a deep-settled suture underneath the investigated segment of the Vardar Ocean. The results further show that a short tectonic uplift and karstification episode occurred in connection with the compressional interruption, affecting the lithospheric-scale contact between formerly descending and overriding NeoTethyan slabs. Thus, the proposed short regional-scale lowermost Cretaceous uplift and karstification episode was likely induced by the closure of the Neotethyan Vardar Ocean. This latest Jurassic-earliest Cretaceous collisional event produced a short compressional episode, lifting up the investigated segment of overriding East Vardar Zone
A Note on the Effect of Statistical Sample Size on Fracture Toughness Characterization in the DTB Transition Region
Get PDFThe ferritic steels, widely used as pressure-vessel materials in nuclear industry, are prone to embrittlement when exposed to neutron irradiation or temperature reduction within the DTB (ductile-to-brittle) transition region. This embrittlement may be accompanied by the increased size effect, which is a pronounced consequence of fracture mechanics not exhibited in the traditional plasticity theory. Therefore, the fracture toughness in the DTB transition temperature region is a stochastic extrinsic property well known for its aleatory variability. Consequently, the extremely-pronounced experimental data scatter necessitates the use of the statistical approach to material characterization. The recently proposed two-step-scaling approach to estimate the size effect of fracture toughness CDF (cumulative density function) in the DTB transition region relies heavily on regularity of arrangement of experimental data points for the two input sample sizes. This regularity of measurement values becomes an inherently iffy proposition in the case of statistically small data sets. Therefore, the ability of our novel approach to predict objectively the fracture toughness probability outside the experimental domain may be impaired in absence of the sufficient statistical size of the input data sets. Since the large-scale fracture toughness tests for nuclear pressure-vessel steels at low temperatures are very expensive, the present study is concerned with this issue of the statistically sufficient sample size. There are various statistical techniques to determine the sample size needed for a study, including power analysis and sample size calculation formulas. The appropriate method depends on the type of study, the research question, and the statistical analysis planned. These issues are addressed in this article.The papers presented at the Ninth International Congress of the Serbian Society of Mechanics (July 5-7, 2023, Vrnjačka Banja, Serbia) were not published in the usual proceedings format, neither in paper nor in electronic form, but only as a collection of peer-reviewed and accepted articles published at the congress internet site
Silicon‐Phosphate Obtained from Rice Husk: a Sustainable Alternative to Phosphate Fertilizer Evaluated for Barley and Maize in Different Soils
No full textThe aim of this study was to evaluate a new silicon and phosphorus containing fertilizer, obtained from rice husk with phos- phoric acid, in comparison with conventional triple super phosphate fertilizer, in terms of shoot growth, phosphorus and silicon uptake in barley and maize plants grown in both acidic and alkaline soils. The functional and structural properties of the silicon phosphate fertilizer were determined by Fourier-transform infrared spectroscopy and X-ray diffraction analysis; plant trials were established, firstly in barley and then subsequently in maize to simulate a crop rotation. Phosphorus sources were applied at the rates of 0, 20, and 80 mg kg−1 soil, and plants were grown in four different soils ranging in pH from 4.8 to 8.4 to determine the main and residual effect of silicon and phosphate fertilization. Dry weights of plants increased significantly in response to phosphorus fertilization in all soils, except for Nigde soil where a high level of plant-available phosphorus was present. The silicon phosphate treatments were more effective than triple super phosphate in obtaining a dry weight increase, especially in case of the subsequent crop maize. Phosphorus treatments increased the shoot concentration and total shoot uptake of phosphorus in barley and maize. These increases were more pronounced at the sufficient phosphorus dose of silicon phosphate. Shoot silicon concentrations of barley significantly decreased with phosphorus treatments, but total uptake of silicon increased in alkaline soils. However, shoot concentration and total uptake of silicon in the subsequent crop maize were higher, especially in case of the silicon phosphate treatments. In acidic soils, the treatments had no effect on the silicon concentration of the barley plant. This study indicates that new silicon phosphate fertilizer produced by hydrolysis of rice husk by using phosphoric acid represents a sustainable alternative to triple super phosphate, and it might be also a valuable source of silicon, especially in case of the subsequent crops in crop rotation systems
Phylogeographic Analysis of Soft-Rot-Causing Pectobacterium spp. Strains Obtained from Cabbage in Serbia
Get PDFThe aim of this study was to establish a link between genetic diversity and the geographic
origin of Pectobacterium strains belonging to three species—P. carotovorum, P. versatile, and P. odoriferum—isolated from cabbage in Serbia by comparing their sequences with those of strains sourced from different hosts and countries in Europe, Asia, and North America. Phylogeographic relatedness was reconstructed using the Templeton, Crandall, and Sing’s (TCS) haplotype network based on concatenated sequences of the housekeeping genes dnaX, icdA, mdh, and proA, while pairwise genetic distances were computed by applying the p-distance model. The obtained TCS haplotype networks indicated the existence of high intra-species genetic diversity among strains of all three species, as reflected in the 0.2–2.3%, 0.2–2.5%, and 0.1–1.7% genetic distance ranges obtained for P. carotovorum, P. versatile, and P. odoriferum, respectively. Five new haplotypes (denoted as HPc1–HPc5) were detected among cabbage strains of P. carotovorum, while one new haplotype was identified for both P. versatile (HPv1) and P. odoriferum (HPo1). None of the TCS haplotype networks provided evidence of significant correlation between geographic origin and the determined haplotypes, i.e., the infection origin. However, as haplotype network results are affected by the availability of sequencing data in public databases for the used genes and the number of analyzed strains, these findings may also be influenced by small sample size
Differences in Chemical Composition of the Essential Oils of Peppermint (Mentha x piperita L.) and Spearmint (Mentha spicata L.) and their Anthelmintic Properties
Get PDFPlants of the genus Mentha are well-known for their various medicinal properties including anti-inflammatory, antiemetic, antispasmodic, analgesic and antiparasitic effects, which are used for the treatment of various gastrointestinal and respiratory diseases. The aim of this study was to determine the chemical composition of the essential oils (EOs) of two Mentha species, peppermint (M. piperita) and spearmint (M. spicata), and to evaluate their anthelmintic activity against gastrointestinal nematodes, parasites that have a significantly negative impact on modern sheep farming. The main compounds of peppermint EO, determined by GC-MS analyses, were menthol (32.6%), menthone (22.0%) and isomenthone (9.39%), and those of spearmint were carvone (64.4%), trans-4-caranone (8.67%) and limonene (4.37%). Their anthelmintic effects, assesed using the egg hatch test conducted at eight different concentrations (50, 12.5, 3.125, 0.781, 0.195, 0.049, 0.025 and 0.0125 mg/ml), were 20.0-90.3% and 13.0-93.7%, respectively. Although both tested samples showed high and dose-dependent (R2 = 0.93 and 0.96, respectively) anthelmintic
potential, their effect was significantly different at five concentrations (p<0.05). The obtained results suggest the high influence of differences in chemical composition of EOs on their pharmacological properties, although the samples were extracted from similar plant species. These should not be neglected during the preparation of formulation, which is important for finding alternatives to combat resistance in nematode
Effects of selected inorganic chemical activators on properties and hydration mechanism of high volume fly ash (HVFA) binders
Get PDFEffects of Na2SO4, Na2CO3, and Na2SiO3 on setting time, compressive strength (up to 90 days), and hydration mechanism of binders with high volume (70 wt%, HVFA binders) of fly ash (FA) were investigated. Before chemical activation, FA was mechanically activated. Effects of the activators on hydration process were examined by isothermal calorimetry, X-ray diffraction and thermogravimetric analyses, and scanning electron microscopy. Pore solution analyses were also performed. It was found that, with addition of the chemical activators, Portland cement (PC) hydration was accelerated and the pozzolanic reaction started earlier, which resulted in shortening of setting time and increase in early compressive strength of the HVFA binders. Combination of mechanical activation of FA and the chemical activation by sodium silicate proved to be the best choice for synthesis of HVFA binder with good physicomechanical properties
Interdimensional radial discrete diffraction in Mathieu photonic lattices
Get PDFWe demonstrate transitional dimensionality of discrete diffraction in radial-elliptical photonic lattices. Varying the order, characteristic structure size, and ellipticity of the Mathieu beams used for the photonic lattices generation, we control the shape of discrete diffraction distribution over the combination of the radial direction with the circular, elliptic, or hyperbolic. We also investigate the transition from one-dimensional to two-dimensional discrete diffraction by varying the input probe beam position. The most pronounced discrete diffraction is observed along the crystal anisotropy direction
Mitochondrial nanomotion measured by optical microscopy
Get PDFNanometric scale size oscillations seem to be a fundamental feature of all living organisms on Earth. Their detection usually requires complex and very sensitive devices. However, some recent studies demonstrated that very simple optical microscopes and dedicated image processing software can also fulfill this task. This novel technique, termed as optical nanomotion detection (ONMD), was recently successfully used on yeast cells to conduct rapid antifungal sensitivity tests. In this study, we demonstrate that the ONMD method can monitor motile sub-cellular organelles, such as mitochondria. Here, mitochondrial isolates (from HEK 293 T and Jurkat cells) undergo predictable motility when viewed by ONMD and triggered by mitochondrial toxins, citric acid intermediates, and dietary and bacterial fermentation products (short-chain fatty acids) at various doses and durations. The technique has superior advantages compared to classical methods since it is rapid, possesses a single organelle sensitivity, and is label- and attachment-free