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Crystallographic investigation of the iron phosphate tungsten bronze (Fe-PWB)
No full textIn this paper, 12-tungstenphosphoric acid (PWA) was synthesized in combination with FeCl3 at room temperature (25 oC). At such manner, Fe3+ ion exchange gave new 12-tungstenphosphoric salt of the transition metal iron (FePW12O40×nH2O; Fe-PWA). Thermal analysis determined the temperature of about 596 oC of the phase transition, i.e., the temperature at which the structure of the Kegin anion is disturbed. Therefore, it was chosen temperature above the breakdown of the Kegin anion of 650 oC, and which is required to obtain phosphate tungsten bronzes (PWB) doped with iron (Fe-PWB). The sample was kept in the oven for 10 minutes. Such obtained new Fe-PWB doped bronze was further investigated by the X-ray powder diffraction (XRPD) and Rietveld methods. The XRPD patterns of Fe-PWA and Fe-PWB were taken in the 3-90o 2θ angle range, and clearly reveal crystallographic and structural differences between these two phases. Determined unit-cell parameters of Fe-PWB obtained by the Rietveld method in the monoclinic crystallographic system are as following: a0 = 7.53(2) Å; b0 = 7.51(1) Å; c0 = 7.64(1) Å; β0 = 89.7(2)o; and V0 = 431(2) Å3. These unit-cell parameters were compared with PWB, as well as other previously doped bronzes (Li-PWB and Ca-PWB). It can be concluded that inserting of the Fe3+ ion into the PWB’s structure was undoubtedly proven, and have the most influence to the axis a0 (i.e., it significantly increased), angle β0 (i.e., it significantly decreased), and volume V0 (i.e., it significantly increased). On the other hand, influence to the axis c0 is quite smaller (i.e., it slightly decreased), whereas influence to the axis b0 is minor. Such behavior is also very different in comparison to the Li-PWB and Ca-PWB
Revealing natural fluorescence in transparent insect wings by linear and nonlinear optical techniques
No full textFor most natural organisms, the physical, chemical and biological aspects of fluorescence emission are poorly understood. For example, to the best of our knowledge, fluorescence from the transparent wings of any of the 3000 known species of cicadas has never been reported in the literature. These wings are known to exhibit anti-reflective properties arising from quasi-periodic arrays of nipples. Our study, using linear and nonlinear optical techniques, including spectrofluorimetry, two-photon fluorescence spectroscopy and Second Harmonic Gener-ation (SHG), reveals the fluorescence properties in the wings the grey and the common cicadas (Cicada orni and Lyristes (Tibicen) plebejus, respectively), as well as the broad-bordered bee hawk-moth (Hemaris fuciformis). The study suggests that fluorescence would be more widespread in transparent insect wings than what was previously believed. Comparing this result to the fluorescence emission from the wings of the Bornean damselfly (Vestalis amabilis), we inferred that this emission probably arises from resilin, a protein reported to enhance wing flexi-bility. Moreover, the nonlinear optical investigation of the insects' wings provided further insight into wing structure, indicating that multiphoton techniques add valuable information for the analysis of insect in-teguments. The strong SHG signal detected from the wing veins implies that these veins are materially organised in a non-centrosymmetric and hence non-random fashion
Artificial neural network and random forest regression models for modelling fatty acid and tocopherol content in oil of winter rapeseed
No full textWith the aid of models used in artificial intelligence, a wide range of data can be processed quickly with high accuracy. The quality of rapeseed oil from 40 genotypes cultivated during four consecutive years was analysed. Two machine learning techniques (artificial neural network - ANN, and random forest regression - RFR) were applied for the modelling of fatty acids content (C16:0; C18:0; C18:1; C18:2; C18:3 and C22:1), alpha-tocopherol, gamma-tocopherol and total tocopherols, according to the data of production year and winter rapeseed genotype. The developed models exerted high-quality anticipation features, showing high r2 during the training cycle. The best fit between the modelled and measured traits for ANN model was observed for erucic acid content. RFR modelling for all fatty acids was more effective than ANN model, with the highest precision for palmitic, stearic, and oleic fatty acids (r2>0.9). This study emphasized the possibility of using ANN and RFR models to model winter rapeseed quality traits
ActivityCoefficients of the System {yKCl + (1-y)KH2PO4}(aq) at T=298.15 K Determined by Cell Potential Measurements
No full textZero-current cell potential measurements were used to determine the solution activity coefficient in a ternary system {yKCl + (1 - y) KH2PO4}(aq) at temperature T = 298.15 K. The cell of the type K-ISE|KCl(mKCl), KH2PO4(mKH2PO4)|Ag|AgCl was used in the total ionic strength range, Im = 0.0886-1.0046 mol kg-1. In order to generate a set of parameters that can be applied in a wide range of mixed solution ionic strengths, the Pitzer, Scatchard, and Clegg-Pitzer-Brimblecombe models were used to fit all available experimental data, including cell potential and isopiestic measurements from the literature. The experimental and calculated values of thermodynamic properties for the studied system are in excellent agreement. Potential interactions and solution structure were discussed by means of the excess free energy of mixing via potential pairs, triplets, or quads for the investigated solution using the Scatchard model mixing parameters
Nanomechanical properties of PVDF–ZnO polymer nanocomposite
No full textPoly(vinylidenefluoride)–ZnO (PVDF–ZnO) nanocomposites with mechanically activated ZnO nanoparticle fillers were investigated using thermal and mechanical analysis and AFM and PFM. Differential scanning calorimetry (DSC) investigated the effect of ZnO nanoparticles on the crystallinity of the polymer, under controlled heating and cooling. Atomic force (AFM) microscopy was used to record the surfaces of the samples. Nanocomposite surface roughness shows the presence of the different phases inside of the matrix, where rough samples contain a higher proportion of the β phase. PFM was performed to investigate the piezoresponse of the composites. Nanoidentation showed that the mechanical activation of the filler (ZnO) increases the Young modulus with the activation time. Molecular simulations in periodic systems (PVDF–ZnO spherical nanocluster and nanocylinder composite) were used to investigate the influence of particle size and shape on the Young modulus of different phases of PVDF
Surface roughness and cyclic fatigue resistance of reciprocating and novel rotary instruments after use in curved root canals
No full textThis study evaluated surface wear and resistance to fracture of reciprocating and novel rotary instruments after use in curved canals. Twenty new instruments (n = 5/each group): Reciproc Blue, WaveOne Gold, XP-endo Shaper (XPS) and TruNatomy were used twice for the instrumentation of simulated curved canals in plastic blocks. The instrumentation was performed according to the manufacturer's instructions at body temperature. Surface roughness was evaluated, using a profilometer, before instrumentation and twice after the instrumentation. Instruments were, then, subjected to a cyclic fatigue test to evaluate the time to failure. Differences were assessed using ANOVA and post hoc tests (alpha = 0.05). The XPS instruments showed significantly higher values of roughness compared with TruNatomy at every stage, especially after the second use (p LT 0.008). Reciprocating instruments showed superior cyclic fatigue resistance compared with novel rotary instruments (p LT 0.05). TruNatomy showed minimal surface roughness, and XPS exhibited significantly higher surface roughness
Prototype of an Innovative Vacuum Dryer with an Ejector System: Comparative Drying Analysis with a Vacuum Dryer with a Vacuum Pump on Selected Fruits
No full textThe following article describes new research about the design, construction and installation of the new prototype of a vacuum dryer with an ejector system. Moreover, the testing of this new prototype involved comparing the qualities of fruit dried in a vacuum drier with an ejector system to fruit dried in a convectional vacuum drier. The data obtained were then analyzed and presented. Due to their economic relevance and highly valuable nutritional value and sensory properties, sour cherries and apricots have been chosen to be the subjects for the testing. The most appropriate quality indicators for analyzing were moisture content, aw value, share and penetration force, total phenol, flavonoid and anthocyanin content and antioxidant activity (FRAP, DPPH and ABTS test). The main results of this study were achieved by designing, constructing, installing and testing the usage of the innovative prototype of a vacuum dryer with an ejector system in the laboratory of the Technology of fruit and vegetable products of the Faculty of Technology Novi Sad, University of Novi Sad. Based on our analyses of the obtained data, it was concluded that vacuum dryer with an ejector system are similar to vacuum dryer with a vacuum pump in terms of all tested physical, chemical and biological properties of dried samples. We observed similarities in some of the most important parameters, including product safety and quality, such as the aw value and the total phenol content, respectively. For example, in dried sour cherry, the aw values ranged from 0.250 to 0.521 with the vacuum pump and from 0.232 to 0.417 with the ejector system; the total phenol content ranged from 2322 to 2765 mg GAE/100 g DW with the vacuum pump and from 2327 to 2617 mg GAE/100 g DW with the ejector system. In dried apricot, the aw ranged from 0.176 to 0.405 with the vacuum pump and from 0.166 to 0.313 with the ejector system; total phenol content ranged from 392 to 439 mg GAE/100 g DW with the vacuum pump and from 378 to 428 mg GAE/100 g DW with the ejector system
Socio-Economic Analysis of the Construction and Building Materials' Usage-Ecological Awareness in the Case of Serbia
No full textThe main idea of the present study was to investigate the impact of the ongoing world crisis on the socio-economic issues in Serbia concerning building materials usage and purchase. This research fills in the gaps in the literature and contributes to the comprehension of how the crisis has affected salaries, market pricing, and materials consumption in the building sector. The data are gathered through a questionnaire and analyzed using a statistical methodology (frequencies, descriptive statistics, and Spearman's correlations). Most of the former studies investigated the surveys conducted on specialists in the field, while this study analyzed the perspectives of random people. Socio-demographic issues are analyzed along with materials consumption before and after the crisis. A special emphasis is given to ecological awareness and novel materials usage. Additionally, it captures a broad shift in the economy and ecological consciousness in a developing country. The majority of respondents are open to using novel building materials and products, but their choice would largely be influenced by cost, the amount of effort involved, and their understanding of the advantages. Statistical approaches revealed that the crisis has a considerable impact on the markets for construction and building supplies, altering consumers' decisions when purchasing. This contribution lays the groundwork for developing countries in the modern world to improve sustainability and adopt circular thinking. Professionals in Serbia need to have a more eco-aware mindset and enhance how they provide pertinent information to potential clients. This study is limited by the number of respondents. For future mathematical modeling and forecasting, more answerers are needed
Photocatalytic performance of TiO2/zeolites under simulated solar light for removal of atenolol from aqueous solution
No full textRemoval of the beta-blocker atenolol from an aqueous solution was studied using TiO2/zeolites, prepared by a simple and cost-effective solid-state dispersion method. Synthetic zeolites 13X and ZSM-5 (Si/Al= 40) and natural zeolite clinoptilolite were used as one component of the hybrid materials, whereas TiO2 nanocrystals obtained from TiO2 nanotubes and P25 TiO2 nanoparticles were used as the other. The synthesized materials were characterized by X-ray powder diffraction, transmission electron microscopy, Fourier transformed infrared spectroscopy, ultraviolet-visible diffuse reflectance spectroscopy and scanning electron microscopy with energy-dispersive spectroscopy. The photocatalytic activity for the degradation of atenolol was investigated under simulated solar light. Additionally, the effect of initial pH on atenolol removal and the reusability of prepared catalysts were tested. The best loading of TiO2 was 20 wt% over all investigated zeolites. The degradation of atenolol followed the pseudo-first-order kinetics. The photocatalytic degradation of atenolol after 70 min of irradiation was similar to 50% for TiO2/13X materials, similar to 45% for clinoptilolite combined with P25 TiO2 and similar to 57% for clinoptilolite combined with TiO2 nanocrystals obtained from TiO2 nanotubes. The results showed the highest removal efficiency after 70 min of irradiation for ZSM-5 combined with P25 TiO2 (similar to 94%), followed by ZSM-5 combined with TiO(2 )nanocrystals obtained from TiO2 nanotubes (similar to 88%) at near-neutral pH (similar to 6.5). The total removal of atenolol from an aqueous solution for TiO2/ZSM-5 materials resulted from two processes: adsorption and photocatalytic degradation. The TiO2/ZSM-5 photocatalysts can be easily recovered and reused as their activity was preserved after four cycles