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1
Content available remote Inspirowane kwantowo sieci neuronowe typu Hopfielda
PL
W pracy przedstawiono koncepcję sieci neuronowej o zespolonych parametrach (Q-inspired). Realizacja takiej sieci wykorzystuje hermitowską macierz połączeń pomiędzy neuronami. Zaproponowano również model uczenia maszynowego zrealizowany na bazie zespolonego aproksymatora. Wykazano przydatność takiego aproksymatora w analizie sygnałów w szczególności do realizacji dyskretnej transfomacji Fouriera (DFT) oraz odwrotnej dyskretnej transformacji Fouriera (IDFT).
EN
The paper presents the concept of a neural network with complex-valued parameters (Q-inspired). Implementation of such a network uses the Hermitian matrix of connections between neurons. A machine learning model based on a complex approximator has also been proposed. The usefulness of such an approximator in signal analysis has been demonstrated especially for the implementation of discrete Fourier transform (DFT) and inverse discrete Fourier transform (IDFT).
EN
Environmental pollution due to humankind’s often irresponsible actions has become a serious concern in the last few decades. Numerous contaminants are anthropogenically produced and are being transformed in ecological systems, which creates pollutants with unknown chemical properties and toxicity. Such chemical pathways are usually examined in the laboratory, where hours are often needed to perform proper kinetic experiments and analytical procedures. Due to increased computing power, it becomes easier to use quantum chemistry computation approaches (QCC) for predicting reaction pathways, kinetics, and regioselectivity. This review paper presents QCC for describing the oxidative degradation of contaminants by advanced oxidation processes (AOP, i.e., techniques utilizing •OH for degradation of pollutants). Regioselectivity was discussed based on the Acid Blue 129 compound. Moreover, the forecasting of the mechanism of hydroxyl radical reaction with organic pollutants and the techniques of prediction of degradation kinetics was discussed. The reactions of •OH in various aqueous systems (explicit and implicit solvation) with water matrix constituents were reviewed. For example, possible singlet oxygen formation routes in the AOP systems were proposed. Furthermore, quantum chemical computation was shown to be an excellent tool for solving the controversies present in the field of environmental chemistry, such as the Fenton reaction debate [main species were determined to be: •OH < pH = 2.2 < oxoiron(IV)]. An ongoing discussion on such processes concerning similar reactions, e.g., associated with sulphate radical-based advanced oxidation processes (SR-AOP), could, in the future, be enriched by similar means. It can be concluded that, with the rapid growth of computational power, QCC can replace most of the experimental investigations related to the pollutant’s remediation in the future; at the same time, experiments could be pushed aside for quality assessment only.
EN
The electronic, optical and thermoelectric properties of MoS2 nano-sheet in presence of the ru impurity have been calculated by density functional theory framework with generalized gradient approximation. The MoRuS2 nano-sheet electronic structure was changed to the n-type semiconductor by 1.3 eV energy gap. The optical coefficients were shown that the loosing optical energy occurred in the higher ultraviolet region, so this compound is a promising candidate for optical sensing in the infrared and visible range. The thermoelectric behaviors were implied to the good merit parameter in the 100K range and room temperatures and also has high amount of power factor in 600K which made it for power generators applications.
EN
In this work, a highly effective catalyst (MoO3) is synthesized and applied for catalytic wet air oxidation (CWAO) treatment of pharmaceutical wastewater. The catalyst is systematically characterized to investigate the morphology, crystal structure and chemical composition, and the findings demostrated that MoO3 catalyst is successfully synthesized. The degradation mechanism is also illustrated by the density functional theory (DFT) calculation. The degradation experiments confirm that MoO3 catalyst exhibits excellent catalytic performance in CWAO, and the removal rate of TOC (Total Organic Carbon) and COD (Chemical Oxygen Demand) is achieved to more than 93%. The catalyst doses, reaction temperature and reaction time have a significant impact on the removal of pollutants. The degradation process of pollutants in CWAO could be satisfactorily fitted by the second-order kinetics. Besides, MoO3 displays a favorable stability as CWAO catalyst. DFT calculation illustrates that MoO3 catalyst is a typical indirect band gap semiconductor. Moreover, the high temperature environment provides the thermal excitation energy, which favors to the free electrons nearing Fermi level to escape the material surface, and excites them to the conduction band, then directly reduces the pollutants in CWAO. These findings demonstrate that MoO3 can be used as an efficient and excellent catalyst for CWAO of pharmaceutical wastewater.
PL
W pracy zbadano wpływ podstawienia atomu wolframu atomem żelaza w pierwszorzędowej strukturze heteropolikwasu fosforowolframowego o budowie anionu Keggina. Charakterystykę struktury elektronową zmodyfikowanego heteropolikwasu przeprowadzono za pomocą: analizy populacyjnej NBO, całkowitych (PDOS) i parcjalnych (PDOS) widm gęstości stanów, energetyki i charakteru chemicznego orbitali granicznych (HOMO/LUMO) oraz rozmiaru przerwy wzbronionej (gap). Dodatkowo zbadano mechanizm oddziaływania modyfikowanego kationem Fe2+ heteropolikwasu fosforowolframowego z cząsteczką H2O pełniącą rolę środowiska reakcji chemicznej. W większości charakterystyk stwierdzono istotny wpływ wprowadzonego metalu przejściowego na ww. właściwości w stosunku do heteropolikwasu wyjściowego H3PW12O40.
EN
In this paper the influence of substituting the tungsten atom with an iron ion in the primary structure of the phosphotungstic heteropolyacid with the Keggin anion structure was investigated. Characterization of the electronic structure of the modified heteropolyacid was performed using: population analysis according to NBO scheme, total (TDOS) and partial (PDOS) density of states spectra, energy and chemical character of frontier orbitals (HOMO / LUMO) and the size of the HOMO-LUMO band gap. Additionally, the mechanism of interaction between the Fe2+ with H2O molecule, acting as a chemical reaction medium, was investigated. Most cases showed a significant effect of the introduced transition metal ion (Fe2+) on the above-mentioned properties in relation to the nonmodified heteropolyacid H3PW12O40.
EN
In this article, synthesis, electronic and optical properties of an N-cyclohexyl-acrylamide (NCA) molecule are described based on different solvent environments and supported by theoretical calculations. Theoretical calculations have been carried out using a density function theory (DFT). Temperature dependence of the sample electrical resistance has been obtained by a four-point probe technique. Experimental and semitheoretical parameters such as optical density, transmittance, optical band gap, refractive index of the NCA for different solvents were obtained. Both optical values and electrical resistance values have shown that NCA is a semiconductor material. The values of HOMO and LUMO energy levels of the headline molecule indicate that it can be used as the electron transfer material in OLEDs. All results obtained confirm that the NCA is a candidate molecule for OLED and optoelectronic applications.
EN
In this research, a series of Ru(II) complexes, ([Ru(1-7)(ina)(NCS)2] (1-7=5-[6-(5-mercapto-1,3,4-oxadiazol-2-yl)pyridin- 2-yl]-1,3,4-oxadiazole-2-thiol’s, ina=isonicotinic acid) were synthesized and characterized using different spectroscopic and analytic techniques, such as NMR, UV, IR, CV and CHN. Also, the new complexes were used in dye-sensitized solar cells (DSSC) as sensitizers. Current-voltage characteristics showed that the modifications of ligands clearly affected DSSC yield. Additionally, DFT calculations were performed and showed locations of frontier molecular orbitals of the complexes. While the locations of HOMO and HOMO – 1 orbitals are on Ru(II) metal center and SCN− ligands, the location of LUMO and LUMO + 1 orbitals are on the 1-7 ligands.
EN
The geometries, electrostatic potential, Mulliken charge analysis, Natural Bond Orbital analysis and polarizabilities of propyl-para-hydroxybenzoate were calculated using B3LYP functional with 6-311++G(d,p) basis set. The calculated geometries are well matched with the experimental values. The Mullliken atomic charge analysis shows that the eventual charges are contained in the molecule. The NBO analysis explains the intramolecular charge transfer in the PHB molecule. The bonding features of the molecule were analyzed with the aid of Hirshfeld surface analysis. The frontier molecular orbital analysis showed the charge transfer obtained within the molecule. The calculated hyperpolarizability of the PHB molecule was 6.977E -30 esu and it was 8.9 times that of standard urea molecule.
EN
The half-metallic, mechanical, and transport properties of the quaternary Heusler compound of PdZrTiAl is discussed under hydrostatic pressures in the range of –11.4 GPa to 18.4 GPa in the framework of the density functional theory (DFT) and Boltzmann quasi-classical theory using the generalization gradient approximation (GGA). By applying the stress, the band gap in the minor spin increases so that the lowest band is obtained 0.25 eV at the pressure of –11.4 GPa while the maximum gap is calculated 0.9 eV at the pressure of 18.4 GPa. In all positive and negative pressures, the PdZrTiAl composition exhibits a half-metallic behavior 100% spin polarization at the Fermi level. It is also found that applying stress increases the Seebeck coefficient in both spin directions. In the minority spin, the n-type PdZrTiAl, the power factor (PF) for all the cases is greater in the equilibrium state than the strain and stress conditions whereas in the majority spin, the PF value of the stress state is greater than the other two. The non-dimensional figure of merit (ZT) is significant and is about one in spin down in the room temperature for the all pressure states that it remains on this value by applying pressure. The obtained elastic constants indicate that the PdZrTiAl crystalline structure has a mechanical stability. Based on the Yong (E), Bulk (B) and shear (G) modulus and Poisson (n) ratio, the brittle-ductile behavior of this compound has been investigated under pressure. The results indicate that PdZrTiAl has a ductile nature and it is a stiffness compound in which elastic and mechanical instability increases by applying strain.
EN
In the current article we would like to summarize our research shedding light onto properties of intramolecular hydrogen bonds present in N-oxide quinoline derivatives. The compounds for the current study were chosen to contain diverse types of hydrogen bonds. Therefore, in the current study we analyze three kinds of hydrogen bonding and their properties. It is well known, that the presence of intramolecular hydrogen bonds stabilizes conformations of molecules. Substituent effects (inductive and steric) influence the strength of the H-bonding as well as its features. Moreover, the intramolecular hydrogen bond in the studied N-oxides belongs to the family of resonance assisted hydrogen bonds (RAHB). Our short overview presents the summary of results obtained for twelve N-oxides of quinoline derivatives. Quantum-chemical simulations were performed on the basis of static models (classical DFT and MP2 approaches) as well as ab initio molecular dynamics (Car-Parrinello MD). The metadynamics method was applied to reproduce the maps of free energy for the motion of the bridged proton. The computations were performed in the gas and in the crystalline phases. Electronic ground state is a natural framework in which chemical compounds exist most of the time. However, in many chemical species we observe a spontaneous internal reorganization of their chemical bonds and atoms e.g. proton transfer phenomenon and the appearance of tautomeric forms already in the ground state. Therefore, it was interesting to investigate some N-oxides in the excited electron state knowing that they exhibit excited- state-induced proton transfer (ESIPT effect). At the end of the article we draw some conclusions related to the intramolecular H-bond properties present in the discussed N-oxides of quinoline derivatives.
EN
The modification of electron states and the change in the geometry of the structure of molecule during hopping transport of charge carriers depends on the symmetry of the molecule. During electric transport the molecule reversibly transforms from neutral state to cation when hole conductivity occurs or to anion when electron conductivity occurs. The energies of orbitals HOMO and HOMO-1 of anthrone and anthrachinone are always negative, what allows for holes transport. Positive energies of LUMO and LUMO+1 orbitals of anion of anthrone and anthraquinone in structure of anion or neutral molecule make electron transport difficult.
PL
Wyniki obliczeń jednoznacznie wskazują na dużą stabilność kationów antrachinonu i antronu. Realizacja przewodnictwa dziur jest w tej sytuacji możliwa dla obu materiałów. Wysoka dodatnia wartość poziomów LUMO i LUMO+1 dla antrachinonu powyżej 1,8 eV nie pozwala na uzyskanie stabilnego przewodzenia elektronów w fazie stałej antrachinonu. Jednak ujemna wartość poziomu HOMO dla anionu pozwala na przejście cząsteczki w fazie stałej do podstawowego poziomu anionu w stanie jonizacji +1. Pozwala to na wykorzystanie antrachinonu w postaci fazy stałej dla potrzeb technologii wykorzystującej środowisko elektrochemiczne. Wysoka wartość dodatnia poziomów HOMO oraz LUMO i LUMO +1 dla anionu antronu utrudnia uzyskanie efektywnego przewodzenia elektronów dla zastosowań w technologii elektroniki organicznej. Jednak dzięki posiadaniu podstawnika, własności anionu antronu są korzystniejsze dla zastosowań niż własności anionu niepodstawionego antracenu. Pomimo podobieństwa cząsteczek i struktur, w jakich krystalizują, występuje znacząca różnica w wartości przerwy energetycznej Eg pomiędzy antronem i antrachinonem. Uzyskane wyniki wskazują na inne obszary możliwych zastosowań antrachinonu i antronu w elektronice organicznej. Wysoka wartość energii przerwy zabronionej może być korzystna dla zastosowań obu materiałów do wytwarzania warstw aktywnych w komórkach słonecznych, gdzie wymagana jest wysoka rezystywność ze względu na konieczność rozdziału generowanych ładunków.
EN
Quantum-chemical calculations indicate that the bond lengths in the anthraquinone anthracene backbone are shorter than the corresponding bonds in unsubstituted anthracene. The shape of the frontier molecular orbitals (FMO) indicates the possibility of more efficient electron capture by the anthraquinone molecule than by the anthracene molecule while maintaining stability in the conditions prevailing in electrochemical cells. Differential scanning calorimetry (DSC) studies indicate the temperature stability of anthraquinone above the melting point up to 300°C. The glass transition is determined at about 100°C.
PL
Obliczenia kwantowo-chemiczne wskazują, że długości wiązań w szkielecie antracenowym antrachinonu w zewnętrznym pierścieniu benzenowym są krótsze niż odpowiadające im wiązania w niepodstawionym antracenie. Świadczy to o zwiększeniu energii rezonansu w zewnętrznych pierścieniach benzenowych cząsteczki antrachinonu. Kształt orbitali zewnętrznych (FMO) wskazuje na możliwość bardziej efektywnego przejmowania elektronów przez cząsteczkę antrachinonu niż przez cząsteczkę antracenu z zachowaniem stabilności w warunkach panujących w komórkach elektrochemicznych. Badania DSC wskazują na stabilność chemiczną antrachinonu powyżej temperatury topnienia aż do 300°C. Antrachinon w pobliżu temperatury 100°C wykazuje przemianę zeszklenia, poniżej tej temperatury nie wykazuje przemian fazowych. Własności elektryczne i termiczne antrachinonu wskazują na duży potencjał tego związku dla zastosowań w elektronice organicznej.
EN
Understanding of atomic scale interactions of molecular species with mineral surfaces is needed to bring about mineral processing innovation. In this regard, Density Functional Theory (DFT) methods are well suited. In this work, the outcome of leaching synthetic acanthite –a surrogate for a silver-containing sulfide ore- with both cyanide ion and thiourea are studied with DFT considering solvent effects. The results are correlated to the experimental percentage of silver extracted with each of the leaching agents under similar conditions of molar concentration, temperature and percentage of solids. Our calculations show both leaching reactions to be exergonic and of the same order of magnitude in Gibbs energy of reaction than values determined from thermodynamic tables. Also, less favorable Gibbs reaction energies are obtained for cyanidation in absence of oxygen and thioureation in absence of Fe(II) highlighting the impact of oxidants on the exergonicity of the respective global leaching reactions. Finally, analyzing the percentage of silver extracted from acanthite and the absolute value of Gibbs energies of the respective reaction, we conclude that the more exergonic a leaching reaction, the higher percentage of silver is extracted from acanthite, provided that there is no kinetic control of each of the leaching reactions.
EN
This work illustrates the significance of kinetic parameters of nucleation and thermal decomposition for Pyridine-2-carboxylic acid crystals. In the interest of maximizing the growth condition for the production of single crystals, nucleation parameters such as interfacial energy (σ), volume free energy (ΔGv), critical energy barrier for nucleation (ΔG*), radius of the critical nucleus (r*) and nucleation rate (J) were determined from the classical nucleation theory of solubility-enthalpy relation. The optimized geometry of the compound was computed from the DFTB3LYP gradient calculations employing 6-31G(d,p) basis set and its vibrational frequencies were evaluated. Based on the vibrational analysis, the thermodynamic parameters were obtained and the correlative equations between these thermodynamic properties and variation in temperatures were also reported.
EN
Structural, electronic, intrinsic magnetic, anisotropic elastic properties, sound velocities and Debye temperature of Fe1−xMnx B (x = 0, 0.25, 0.5, 0.75, 1) transition metal monoborides have been studied by first-principles calculations within the method of virtual crystal approximation (VCA) based on density-functional theory (DFT) through generalized gradient approximation (GGA). The average magnetic moment per cell increased with increasing of Mn content, which could be associated with the relationship between the composition and magnetic properties. The observed magnetic behavior of Fe1−xMnx B compounds can be explained by Stoner model. Lattice parameters and Debye temperature agree well with the experimental values. Furthermore, we have plotted three-dimensional (3D) surfaces and planar contours of the directional dependent Young and bulk moduli of the compounds on several crystallographic planes, to reveal their elastic anisotropy versus Mn content (x) in Fe (1−x)MnxB.
EN
In this paper, an expert system-based fault detection and classification scheme is developed for a laboratory prototype model of TCSC compensated long transmission line (thyristor controlled series compensator). The equivalent model of laboratory prototype system is simulated in MATLAB Simulink. An expert system based on fuzzy logic is developed by using threephase voltage and current signals from single end measurements. Obtained voltage and current signals are pre-processed with Discrete Fourier Transform (DFT) to obtain the fundamental component of these signals. Further zero sequence current and obtained fundamental voltage and current signals are used to develop a fuzzy inference system (FIS) for shunt fault detection and classification task. There are three different FISs developed for three individual phases of the transmission system and one FIS is developed for zero sequence current signal, which provides ground involvement information. The combined binary output of the developed four FISs provides fault classification. The performance of the developed FISs is rigorously tested with the variation of different fault parameters, and different location of the TCSC. The simulated results indicate that the proposed scheme performance is reliable in its zone of protection.
17
Content available Discrete Fourier transform and permutations
EN
It is well known that the magnitudes of the coefficients of the discrete Fourier transform (DFT) are invariant under certain operations on the input data. In this paper, the effects of rearranging the elements of an input data on its DFT are studied. In the one-dimensional case, the effects of permuting the elements of a finite sequence of length N on its Discrete Fourier transform (DFT) coefficients are investigated. The permutations that leave the unordered collection of Fourier coefficients and their magnitudes invariant are completely characterized. Conditions under which two different permutations give the same DFT coefficient magnitudes are given. The characterizations are based on the automorphism group of the additive group ZN of integers modulo N and the group of translations of ZN. As an application of the results presented, a generalization of the theorem characterizing all permutations that commute with the discrete Fourier transform is given. Numerical examples illustrate the obtained results. Possible generalizations and open problems are discussed. In higher dimensions, results on the effects of certain geometric transformations of an input data array on its DFT are given and illustrated with an example.
PL
Artykuł przedstawia przegląd rozwoju strategii i metod używanych w badaniach na temat stopów o wysokiej entropii. Jest to nowa grupa materiałów, która może być scharakteryzowana poprzez nowoczesne podejście do kompozycji stopowych. Podczas, gdy w tradycyjnych stopach można wyróżnić jeden lub dwa podstawowe elementy, których stężenie jest bardzo wysokie w stosunku do innych pierwiastków stopowych, w stopach o wysokiej entropii pięć lub więcej pierwiastków stopowych dodaje się w równych lub prawie równych proporcjach. Od dawna uważano, że ten rodzaj kompozycji doprowadzi do kruchej konglomeracji związków międzymetalicznych, ale stwierdzono, że wysoka entropia losowych stałych roztworów może je uprzywilejowywać względem innych uporządkowanych, fazowych lub międzymetalicznych związków, prowadząc do prostej jednofazowej struktury. To odkrycie stworzyło nowe, ogromne możliwości projektowania nowych materiałów, ale także konieczność przyjrzenia się istniejącym metodologiom rozwoju stopów.
EN
Paper presents a review of development strategies and methods used in research on high entropy alloys. This is a new group of materials which can be characterised by novel approach to alloy composition. Whereas in traditional alloys we can distinguish one or two base elements whose concentration is very high in relation to other alloying elements, in high entropy alloys five or more alloying elements are added in equal or near equal proportions. It has been long thought that this type of composition will lead to brittle conglomeration of intermetallics, but it was found that high entropy of random solid solutions can preferentiate them over other, ordered, phases or intermetallic compounds leading to simple single phase structure. This discovery created new and vast possibilities for designing new materials, but also necessitated revision of existing methodologies for alloy development.
EN
Secondary activation of commercial activated carbon (AC) ORGANOSORB 10-CO was carried out at 600, 700 and 800°C with mass ratios of potassium to AC (K/AC) in range 1–3. Crucial samples have shown following CO2  uptakes and SSA – 3.90 mmol/g and 1225 m2/g, 4.54 mmol/g and 1546 m2/g, 4.28 and 1717 m2/g for pristine material and samples obtained at 700°C with K/AC = 2 and at 800°C with K/AC = 3 respectively. Last sample also indicated significant mesopore volume increase in diameter range 2–5 nm, from 0.11 to 0.24 cm3/g. CO2 uptake increase was explained by formation of micropores up to diameter of 0.8 nm, which distribution was established from CO2  sorption using DFT. Surface chemistry of all samples has not changed during modification, what was proven by XPS. Moreover, deeper incorporation of potassium ions into graphite at higher temperatures was observed as confirmed with EDS, XPS and XRD.
EN
A novel collector, tert-butyl benzohydroxamic acid (TBHA), was first introduced in rhodochrosite flotation. The performance of TBHA was investigated by the density functional theory (DFT) calculation along with the micro flotation test, zeta potential determination and XPS analysis, compared with benzohydroxamic acid (BHA). TBHA has stronger affinity to the mineral than BHA in terms of frontier molecular orbital, atomic net charge and bond population. The substitution of tert-butyl group on the benzene ring improves the affinity of the hydroxamic acid to the mineral. TBHA exhibits excellent collecting ability to rhodochrosite with a recovery of about 99% at a concentration of 3.89×10-4 mol/dm3 and pH 6.5. The hydroxamic acid molecules are adhered on mineral surfaces by chemical adsorption, resulting in negative shifts for the zeta potential of rhodochrosite with the presence of the collector. Chemical adsorption can be also confirmed from XPS analyses that the atomic concentration ratios of C and O to Mn on the treated mineral surfaces were increased and the binding energy of Mn3s was decreased. The experimental data achieve excellent agreement with the computational analyses.
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