Free Dipole Research Articles

Localized estimation of event-related neural source activity from simultaneous MEG-EEG with a recurrent neural network

Estimating intracranial current sources underlying the electromagnetic signals observed from extracranial sensors is a perennial challenge in non-invasive neuroimaging. Established solutions to this inverse problem treat time samples independently without considering the temporal dynamics of event-related brain processes.This paper describes current source estimation from simultaneously recorded magneto- and electro-encephalography (MEEG) using a recurrent neural network (RNN) that learns sequential relationships from neural data. The RNN was trained in two phases: (1) pre-training and (2) transfer learning with L1 regularization applied to the source estimation layer. Performance of using scaled labels derived from MEEG, magnetoencephalography (MEG), or electroencephalography (EEG) were compared, as were results from volumetric source space with free dipole orientation and surface source space with fixed dipole orientation. Exact low-resolution electromagnetic tomography (eLORETA) and mixed-norm L1/L2 (MxNE) source estimation methods were also applied to these data for comparison with the RNN method.The RNN approach outperformed other methods in terms of output signal-to-noise ratio, correlation and mean-squared error metrics evaluated against reference event-related field (ERF) and event-related potential (ERP) waveforms. Using MEEG labels with fixed-orientation surface sources produced the most consistent estimates.To estimate sources of ERF and ERP waveforms, the RNN generates temporal dynamics within its internal computational units, driven by sequential structure in neural data used as training labels. It thus provides a data-driven model of computational transformations from psychophysiological events into corresponding event-related neural signals, which is unique among MEEG source reconstruction solutions.

Corrosion and heat-resistant SiCN/C as lightweight fibers for microwave absorption and electromagnetic field shielding in Ku-band

SiCN fibers are usually combined with metals to increase the magnetic loss in electromagnetic field (EMF) shielding, but this results in high weight density, easy corrosion, difficult treatment, and high cost of the material. This study proposes the manufacturing of corrosion and heat-resistant ceramic lightweight fibers containing in-situ synthesized carbon nanostructures (SiCN/C) with excellent EMF shielding in Ku-band (12.4–18 GHz). The samples showed differential trends of EMF shielding effectiveness in terms of reflectance, transmittance, and absorption behavior. Compared to SiCN fibers, the EMF absorption was two times greater when carbon was added to the SiCN matrix. A minimum reflection coefficient (S11) of −12 dB was observed for SiCN/C fibers, meaning a high shielding efficiency with >90 % of the EMF energy shielded. On the other hand, SiCN fibers showed a minimum S11 of −7 dB, resulting in a protection of 80 % against EMF energy. Computational simulations clarified the better features of SiCN/C in electromagnetic shielding compared to SiCN, which was ascribed to enhanced conduction loss derived from conductive free carbon, and dipole and interfacial polarization loss generated by defects. The fibers were resistant to acidic and basic environments and oxidation of up to 600 °C. Moreover, the addition of carbon precursor represented a weight decrease of 17 % for SiCN/C compared to SiCN fibers. This research will afford an alternative solution for the manufacturing of SiCN/C fibers with EMF absorption properties that can be used as lightweight materials in harsh environments.

GFN-xTB-Based Computations Provide Comprehensive Insights into Emulsion Radiation-Induced Graft Polymerization.

In this article, a deep insight into emulsion radiation-induced graft polymerization (RIGP) was obtained by computing explicit solvation free energies, conformational entropy, monomer radius and dipole moments with the state-of-the-art Conformer-Rotamer Ensemble Sampling Tool (CREST) package primarily at semiempirical GFN-xTB level. By leveraging the robustness of the CREST package, above parameters provided dynamic nature of methacrylate monomers with the consideration of realistic emulsion conditions. With the chemical and physical importance of the above results, CREST-determined explanatory variables sufficiently led to the building of the prediction models for the RIGP of methacrylate monomers. The machine learning model building resulted in effective reactivity predictions and unveiled important factors for the radiation-induced graft polymerization in a chemically interpretable fashion.

Exploration of DFT and TD-DFT computation to investigate the interaction between paracetamol and lithium or its compounds

Paracetamol is a commonly used antipyretic drug and its consumption drastically was increased during the COVID-19 times as fever was one of the symptoms. The excessive usage of paracetamol could harm humans, as the unused accumulated paracetamol can involve in the reaction with many small molecules as well as can interact with several biomolecules. Lithium chloride in its hydrated form is used as an antimanic drug and a geroprotector. It is needed in very small quantities by humans. Tetrahydrated form of lithium ion is the most stable hydrated form. Herein, the authors have investigated the interaction of paracetamol with tetrahydrated lithium chloride (1:1 and 1:2) using the DFT and TD-DFT calculations at 298 K and 310 K. The interaction of paracetamol with lithium chloride P1 (1:1), P2 (2:1), P3 (3:1) and P4 (4:1) are also studied by DFT calculations in default and CPCM model. The authors have calculated the free energy, optimization energy, dipole moment and other thermodynamic parameters of all the systems. Based on enthalpy and change in Gibbs free energy, the interaction was maximum between the paracetamol and tetrahydrated lithium chloride at 298 K as well as 310 K which indicates that the hydrated lithium chloride is being consumed by unused paracetamol. In P1 and P3, lithium showed interaction with oxygen of phenolic group and other atoms of all the paracetamol molecules present, while in P2 and P4, lithium showed these interactions with only one paracetamol molecule.

Spectrochemical, biological, and toxicological studies of DDT, DDD, and DDE: An in-silico approach

Pesticides are used to control the various pests and disease carriers. Degradation and/or biotransformation alter their chemical and toxicological nature. An attempt has been taken to investigate the physicochemical, spectral, and toxicological nature of DDT [1, 1'-(2, 2, 2-trichloroethylidene) bis(4-chlorobenzene)] and its major derivatives. DDT is transformed into DDD [l, l-dichloro-2, 2-bis(p,p-chlorophenylethane)], and DDE [l, l-dichloro-2, 2-bis(p,p-chlorophenylethylene)] under reductive dechlorination conditions. They last longer in the fatty tissue due to fat-soluble features, and exhibit some harmful effects on the environment and biological systems. Herein, density functional theory along with the CAM-B3LYP/6-311g ++ (d, p) basis set has been employed to investigate their physicochemical, and spectral properties. In-silico methods were incorporated to evaluate their biological, and toxicological properties. Molecular docking and nonbonding interaction calculations were performed to investigate their binding properties and mode(s) of action against the human estrogen receptor (PDB ID: 6PYF), and serine/threonine-protein kinase PIM-2 (PDB ID: 2IWI). Further, molecular dynamics simulation was performed to check the deformability and interactions of protein and amino acid residues, respectively. ADMET (absorption, distribution, metabolism, excretion, and toxicity) and PASS (prediction of activity spectra for substances) predictions were performed to compare their biological and toxicological properties. DDT has the highest free energy, dipole moment, and chemical reactivity; meanwhile, DDE and DDD have the highest binding affinity against both proteins. All the compounds exhibit hepato-toxicological, neuro-toxicological, and carcinogenic properties which depict their toxicological level. Based on their studied parameters, this study can help to increase awareness and provide a deeper understanding of the biochemical, and toxicological impacts on the environment and biological system.

Aging resistance of polyurethane/graphene oxide composite modified asphalt: performance evaluation and molecular dynamics simulation

ABSTRACT To evaluate the effect of polymers and nanomaterials on asphalt after thermo-oxidative aging, the aging resistance of thermoplastic polyurethane modified asphalt (PU-MA), polyurethane/graphene oxide composite modified asphalt (PU/GO-MA) were discussed through experiments and molecular dynamics (MD) simulations. The molecular composition and self-healing ability of aged asphalt were investigated. Base asphalt and virgin asphalt were used as control. The aging experiments of base asphalt, PU-MA and asphalt modified with PU and different content of GO composites were carried out by rolling thin-film oven test. The differential scanning calorimeter, thermal gravimetric analyzer, viscous flow deformation, bending beam rheometer and Fourier transform infrared spectrometer tests were carried out. The molecules and cracks models of asphalt were simulated by MD. The parameters such as mean square displacement, fractional free volume, dipole moment and viscosity were calculated. The results show that PU/GO can affect the transformation among components, increase the melting temperature of asphalt, improve the migration ability of asphalt molecules, enhance the self-healing diffusion movement of asphalt molecules and reduce the energy and viscosity of aged asphalt. In brief, nano and chemical synergistic modification has effects on the properties of asphalt after aging.

Composition-dependent wettability of nature-inspired homo poly(amino acid) coating and its influences on bacterial adhesion

A variety of natural proteins have shown anti-adhesive functionality against the non-specific adsorption by proteins and bacteria. A deep understanding of the contribution of amino acid composition to the antifouling performance of a natural protein is crucial for engineering a protein-based coating layer. Herein, we synthesized five types of homo poly(amino acid)s via the ring-opening polymerization of α-amino acid N-carboxy anhydride (NCA) to include exclusively one type of amino acid from lysine (K), glutamic acid (E), tyrosine (Y), alanine (A), and phenylalanine (F). Homo poly(amino acid)s were covalently immobilized on the surfaces of quartz and polyurethane (PU), respectively. The amino acid composition effects on the wetting and anti-bacterial adhesion of a homo poly(amino acid) coating layer were evaluated. We found that the wettability of homo poly(amino acid) coating layers exhibited a dependence on the intrinsic properties of amino acid side-chain, such as the hydration free energy and dipole moment of side-chain. The activity of a homo poly(amino acid) coating layer against bacterial adsorption was found to be independent of the wetting property of the amino acid side-chain. Our findings are different from the conventional opinion that the hydration property of a material surface coating layer correlates to its anti-bacterial functionality, emphasizing the complexity of the amino acid composition contribution to the activity against the non-specific adsorption of bacteria for a protein-mimicking system.

The theoretical study of anticancer rhodium complexes and methyl groups effect on ligands in chemical reactivity, global descriptors, ADMET by DFT study

As there are a potential application of rhodium (0) complexes and rhodium (II) complexes in anticancer drug discovery, the key point of this study is to design new rhodium(0) complexes with amine ligand, and was estimated their properties. To predict the thermo-physical, chemical reactivity and biological activity of most expected rhodium (0) complexes with amine and alkyl amine were conducted by the computational method of density functional theory (DFT). The thermo-physical parameters, such as free energy, entropy, dipole moment, binding energy, nuclear energy, electronics energy and heat of formation were calculated, as well as chemical reactivity, for example, Highest Occupied Molecular Orbital (HOMO), Lowest Unoccupied Molecular Orbital (LUMO) and HOMO-LUMO gap. Some descriptors, such as ionization potential, electronegativity, hardness, softness and electron affinity were estimated of rhodium (0) complexes. To explain about biological indication, the charge density, surface area grid, volume, LogP, polarizability, refractivity and molecular mass had also calculated. The ADMET was illustrated through the online database AdmetSAR for the safe uses and toxicological evidence. Regarding the chemical reactivity study in view of softness and LUMO HOMO gap, the L03 is a more suitable drug than others, and stands for that secondary alkyl amine as ligand is more effective than primary and tertiary amine ligands.

Impact of Solvent Polarity on the molecular properties of Dimetridazole

Recently molecular activity of dimetridazole (DMZ) gained interested due to medical applications. In this study, a computational investigation of the solvent impact on solvation free energy, dipole moments, polarizability, hyper-polarizability and characteristic atomic properties; hardness and softness quality, chemical potential, electronegativity and electrophilicity have been accounted for DMZ. All forms of the calculation for both gas phase and solution phase used Becke 3-Parameter of Lee-Yang parr (B3LYP) theory with a 631++G basis set. Using the Solvation Model on Density (SMD), the effect of solvent polarity on solvation free energy, dipole moment, polarizability, hyper-polarizability and molecular properties were measured. The dipole moment of the DMZ was lower value in a gas phase comparative with solution phase. Furthermore, the electronegativity and chemical potential were increased from non-polar to polar solvents, while electrophilicity index was decreased. However, in case of chemical hardness & softness, the opposite relationship has been found. The results of this study contribute to an understanding of the molecular activity of DMZ, and stimulate its activity in solution phase. Keywords: Dimetrizole, Solvation model, Dipole moment, Solvent-free energy, Molecule polarizability.

Polarity Free Magnetic Repulsion and Magnetic Bound State

This is a report on a dynamic autonomous magnetic interaction which does not depend on polarities resulting in short ranged repulsion involving one or more inertial bodies and a new class of bound state based on this interaction. Both effects are new to the literature, found so far. Experimental results are generalized and reported qualitatively. Working principles of these effects are provided within classical mechanics and found consistent with observations and simulations. The effects are based on the interaction of a rigid and finite inertial body (an object having mass and moment of inertia) endowed with a magnetic moment with a cyclic inhomogeneous magnetic field which does not require to have a local minimum. Such a body having some degrees of freedom involved in driven harmonic motion by this interaction can experience a net force in the direction of the weak field regardless of its position and orientation or can find stable equilibrium with the field itself autonomously. The former is called polarity free magnetic repulsion and the latter is classified as a magnetic bound state. Experiments show that a bound state can be obtained between two free bodies having magnetic dipole moment as a solution of two-body problem. Various schemes of trapping bodies having magnetic moments by rotating fields are realized as well as rotating bodies trapped by a static dipole field in presence of gravity. Additionally, a special case of bound state called bipolar bound state between free dipole bodies is investigated.

First demonstration of high current canted-cosine-theta coils with Bi-2212 Rutherford cables

Future high energy physics colliders could benefit from accelerator magnets based on high-temperature superconductors, which may reach magnetic fields of up to 45 T at 4.2 K, twice the field limit of the two Nb-based superconductors. Bi2Sr2CaCu2O8-x (Bi-2212) is the only high-T c cuprate material available as a twisted, multifilamentary and isotropic round wire. However, it has been hitherto unclear how an accelerator magnet can be fabricated from Bi-2212 round wires and whether high field quality can be achieved. This paper reports on the first demonstration of high current Bi-2212 coils using Rutherford cable based on a canted-cosine-theta (CCT) design and an overpressure processing heat treatment. Two Bi-2212 CCT coils, BIN5a and BIN5b, were made from a nine-strand Rutherford cable. Their electromagnetic design is identical, but they were fabricated differently: both coils underwent heat treatment in their aluminum–bronze mandrels, but unlike BIN5a that was impregnated with epoxy in its reaction mandrel, the conductor of BIN5b was transferred to a 3D printed Accura Bluestone mandrel after the heat treatment, a process attempted here for the first time, and was not impregnated. BIN5a reached a peak current of 4.1 kA with a self-field of 1.34 T in the bore. This corresponds to a wire engineering current density (J e) of 912 A mm−2, which is two times that of BIN2-IL, a previous Bi-2212 CCT coil fabricated at LBNL, which used a six-around-one cable processed with the conventional 1 bar pressure melt processing. On the other hand, BIN5b reached 3.1 kA. The coils exhibited no quench training. All the quenches were thermal runaways that occurred at the same location. In addition, we report on the field quality and ramp-dependent hysteresis measurements taken during the test of BIN5a at 4.2 K. Overall, our results demonstrate that the CCT technology is a route that should be further investigated for making high field, potentially quench training free dipole magnets with Bi-2212 cables.

Investigation on Electrical Properties of Solid Polymer Sheets (HDPE AND LDPE) at Audio Frequency Range

Two different groups of solid polymer sheets: low density polyethylene (LDPE) sample of thickness 0.006 cm and 0.007 cm along with high density polyethylene (HDPE) sample of the thickness of 0.009 cm, 0.010 cm were taken in this work. The measurement of electrical properties such as dielectric constant, ε' and dielectric loss, ε'' for LDPE and HDPE polymer sheets have been measured using a dielectric cell. The dielectric cell has been fabricated which consists of two circular parallel plates of pure stainless steel each of 5 cm diameter and 2 mm thickness. An impedance bridge (GRA 650A) was used for measurement of capacitance, C, and dissipation factor, D in the audio frequency (AF) range, 100 Hz to 10 kHz. Different samples were loaded in between the two plates of the cell and the capacitance as well as the dissipation factor were estimated from the dial readings of the bridge. Effect of frequency variation on ε', ε'', relaxation time, τ , dissipation factor, tanδ and ac conductivity, σ were also discussed at audio frequency range. The complex permittivity, ε*, related to free dipole oscillating in an alternating field and loss tangent, tanδ were calculated. The frequency-dependent conductivity, dielectric behavior, and electrical modulus, both real (M') and imaginary (M") parts of LDPE and HDPE have been studied in this work. The values of the real part of the electrical modulus (M') did not equal to zero at low frequencies and it is expected that the electrode polarization may develop in both sheets. These findings reveal an increased coupling among the local dipolar motions in a short-range order localized motion. The analysis of real (ε') and imaginary (ε'') parts of dielectric permittivity and that electrical modulus real (M') and imaginary (M") parts signify poly dispersive nature of relaxation time as observed in Cole-Cole plots.

Theoretical and experimental findings regarding the electroanalysis of dienestrol in natural waters using a silver nanoparticles/single-walled carbon nanotubes-based amperometric sensor

Abstract Aware of the irreparable damage that synthetic estrogens can trigger in the environment, the search for analytical methods capable of mapping the sources, levels and fate of these micropollutants is a subject that demands enormous scientific effort. The present work follows this trend, reporting a silver nanoparticles/single-walled carbon nanotubes-based composite electrode (AgNP/SWCNT-CPE) that has multiple functionalities for dienestrol (DNL) electroanalysis. Theoretical and experimental data indicate that DNL reactivity on AgNP/SWCNT-CPE is more critical under acidic conditions, favoring its irreversible oxidation to quinone derivatives. The reaction kinetics is limited by interfacial adsorption events, whose intensity of the molecule-surface interaction depends on variables such as Gibbs free energy, ionization potential, HOMO-LUMO gap, and dipole moment. Since the silver‑carbon heterojunction has low overpotential towards the oxygen evolution reaction, it is speculated that AgNP/SWCNT-CPE is more resistant to surface fouling due to the formation of chemisorbed radicals on its electroactive area. Based on the detection limit (43.7 nmol L−1 DNL), the analytical performance of the proposed method is equivalent to those attained by chemiluminescence, electrophoresis, chromatography and electrochemistry. Given the sensitivity obtained, AgNP/SWCNT-CPE was successfully used to quantify DNL in river waters containing different levels of organic matter, without compromising the accuracy, stability and robustness of the amperometric measurements, reiterating the reliability and feasibility of this proposal.

New Insights into the Structure and Reactivity of Uracil Derivatives in Different Solvents-A Computational Study.

Ab initio calculations were carried out to understand the reactivity and stability of some uracil derivatives, cytosine, 1-methyl cytosine, and cytidine in solvents, water, dimethyl sulfoxide (DMSO), n-octanol, and chloroform. Geometries were fully optimized at MP2 and B3LYP using the 6-31+G(d,p) basis set by applying the Solvation Model on Density (SMD) in solvent systems. The syn conformer of cytidine (cytidine II) is the most stable conformer in the gas phase, while the anticonformer (cytidine IV) is most stable in all of the solvents. Solvation free energy and polarizability values in different solvents decrease in the order water > DMSO > n-octanol > chloroform, while dipole moment, first-order hyperpolarizability, and HOMO–LUMO energy gap values follow the order of polar protic solvent (water and n-octanol) > polar aprotic solvent (DMSO) > nonpolar solvent (chloroform). The solvation free energy, dipole moment, polarizability, and first-order hyperpolarizability values also follow the order of cytosine > 1-methyl cytosine > cytidine. To illustrate that the molecular properties correlate well with the reactivity of the molecules, ab initio calculations were carried out for the reaction of uracil derivatives with Br2 in the gas phase, water, DMSO, n-octanol, and chloroform. All ground and transition state geometries were fully optimized at B3LYP/6-31+G(d,p), and energies were also calculated at G3MP2 for cytosine and 1-methyl cytosine. For cytosine and 1-methyl cytosine, Gibbs energies of activation decrease with the polarity of the solvent that is chloroform > n-octanol > DMSO > water, while the Gibbs energies of activation for the reaction with cytidine decrease in the order of water > DMSO > n-octanol > chloroform. These results suggest that solvent polarity is very important for the stability and reactivity of uracil derivatives. Hydrogen bonding may also play an important role mainly for cytidine. Free energies of activation decrease with the size of the molecule, i.e., cytosine > 1-methyl cytosine > cytidine.

The effect of halogen atoms at propanoate anion on thermo physical, vibrational spectroscopy, chemical reactivity, biological properties of morpholinium propionate Ionic Liquid

The morpholinium cation based ionic liquids are designed to evaluate the thermophysical, chemical reactivity, and biological activity. To estimate and design the bioactive ILs, propionate and trihalopropanoate were considered under theoretical study by Density Functional Theory (DFT). To make effect of halogens atom on anion, propionate, trifluro propionate, trichloro propionate, and tribromo propionate were taken for optimization. Some thermodynamic and thermophysical properties such as free energy, entropy, dipole moment, binding energy, nuclear energy, electronics energy, and heat of formation were calculated using DFT method and make a comparative effect for halogen atoms activity on anion. The free energy, binding energy, and heat of formation were the highest on morphonium trifluro propionate (IL02) and the second is on tribromo propionate (IL04). Quantitative Structure Activity Relationship (QSAR) like charge density, surface area grid, volume, LogP, polarizability, refractivity, and molecular mass were simulated and recorded, from which the biological activity was calculated. The chemical reactivity like HOMO, LUMO, HOMO-LUMO gap, ionization potential, hardness, softness electronegativity and electron affinity were calculated. The vibrational spectroscopy and UV spectroscopy data provide them the identification and characterization. To sum up, the thermophysical properties are highly affected by trifluro propionate anion then tribromo propionate, trichloro propionate, and propionate respectively. On the other hand, the chemical reactivity increases in order IL04, IL03, IL02, IL01 but biological activity is inversely changed.

Reviewing of Synthesis and Computational Studies of Pyrazolo Pyrimidine Derivatives

In this review we synthesized and conducted a computational studies on Pyrazolo pyrimidine’s derivatives that were carried out through density functional theory level utilizing HF/6−311+G**and B3LYP/6−311+G**. Charge transfer occured through molecule was shown by the calculation of HOMO and LUMO energies. The electric dipole moment values (l) of the molecule were counted calculations of DFT. Some geometrical and structural parameters such as total energies (E), relative energies (DE), (bond length in A, angles in degree), energy gap, relative Gibbs free energy, dipole moment, and molecular electrostatic potentials (MEP) were studied.

Synthesis of dipolar molecular rotors as linkers for metal-organic frameworks.

We report the synthesis of five dicarboxylic acid-substituted dipolar molecular rotors for the use as linker molecules in metal-organic frameworks (MOFs). The rotor molecules exhibit very low rotational barriers and decent to very high permanent, charge free dipole moments, as shown by density functional theory calculations on the isolated molecules. Four rotors are fluorescent in the visible region. The linker designs are based on push–pull-substituted phenylene cores with ethynyl spacers as rotational axes, functionalized with carboxylic acid groups for implementation in MOFs. The substituents at the phenylene core are chosen to be small to leave rotational freedom in solids with confined free volumes. The dipole moments are generated by electron-donating substituents (benzo-1,3-dioxole, benzo-1,4-dioxane, or benzo-2,1,3-thiadiazole annelation) and withdrawing substituents (difluoro, or dicyano substitution) at the opposite positions of the central phenylene core. A combination of 1,4-dioxane annelation and dicyano substitution generates a theoretically predicted, very high dipole moment of 10.1 Debye. Moreover, the molecules are sufficiently small to fit into cavities of 10 Å3. Hence, the dipolar rotors should be ideally suited as linkers in MOFs with potential applications as ferroelectric materials and for optical signal processing.

Super- and subradiance of clock atoms in multimode optical waveguides

The transversely confined propagating modes of an optical fiber mediate virtually infinite range energy exchanges among atoms placed within their field, which adds to the inherent free space dipole–dipole coupling. Typically, the single atom free space decay rate largely surpasses the emission rate into the guided fiber modes. However, scaling up the atom number as well as the system size amounts to entering a collective emission regime, where fiber-induced superradiant spontaneous emission dominates over free space decay. We numerically study this super- and subradiant decay of highly excited atomic states for one or several transverse fiber modes as present in hollow core fibers. As particular excitation scenarios we compare the decay of a totally inverted state to the case of π/2 pulses applied transversely or along the fiber axis as in standard Ramsey or Rabi interferometry. While a mean field approach fails to correctly describe the initiation of superradiance, a second-order approximation accounting for pairwise atom–atom quantum correlations generally proves sufficient to reliably describe superradiance of ensembles from two to a few hundred particles. In contrast, a full account of subradiance requires the inclusion of all higher order quantum correlations. Considering multiple guided modes introduces a natural effective cut-off for the interaction range emerging from the dephasing of different fiber contributions.

Conduction and dielectric relaxations in PVA/PVP hydrogel synthesized cerium oxide

Dielectric relaxation at higher frequencies with dc conductivity contribution is observed in PVA/PVP hydrogel synthesized Nano-crystalline Cerium oxide (CeO2), which is a typical oxygen ion conductor. The material is characterized using XRD, FTIR, Raman spectroscopy, SEM, TEM, UV-Vis and Impedance spectroscopy. Impedance spectroscopic data of the material are studied with combined Cole-Cole type conduction and dielectric relaxations and the results revealed that the material possesses two types of dipoles, pinned dipole and free dipole. The electrical parameters extracted from the analysis are found to be independent of ac data representations. The dc conductivity σc, conduction relaxation time τc and dielectric relaxation time τd show Arrhenius behavior. Conduction process follows Barton–Nakajima–Namikawa (BNN) relation and dielectric process follows fractional Debye–Stokes–Einstein (DSE) equation. Time-temperature scaling of complex impedance data suggests that the conduction mechanism is slightly temperature dependent. Intrinsic defects created in the material and hopping of charge carriers generate a combined relaxation in the material.

A new 2,2′-oxydianiline derivative symmetrical azomethine compound containing thiophene units: Synthesis, spectroscopic characterization (UV–Vis, FTIR, 1H and 13C NMR) and DFT calculations

In this study, a new symmetrical azomethine compound, N,N′-oxydiphenylenebis(5-(thiophen-2-yl)salicylidenimine OPBTS (5), having two thiophene rings and N, O donor groups, was successfully prepared by a simple condensation reaction of 2-hydroxy-5-(thiophen-2-yl)benzaldehyde (3) and 2,2′-oxydianiline (4). Characterization of OPBTS was performed by the analysis of UV–Vis., FTIR, 1H and 13C NMR spectroscopic results and elemental analysis. The optimized molecular geometry, sum of electronic and thermal free energies (SETFEs), dipole moment, IR frequencies, 1H and 13C NMR chemical shift values, UV–Vis. spectroscopic parameters, HOMO-LUMO energies, molecular electrostatic potential (MEP) map and atomic charges of OPBTS were calculated by using Density Functional Theory (DFT/B3LYP/6-311 + G(d, p)) method in the gas phase and various solvents. The theoretical results were compared to the experimentally obtained data and all results were found to be compatible. The experimental and theoretical results confirmed the proposed molecular structure for the new synthesized bis-azomethine derivative (OPBTS).