Search

Here, we report curvature‐induced electron spin catalysis by using solid carbon spheres as catalysts, which were synthesized using positive curvature molecular hexabromocyclopentadiene as a precursor molecule, following a radical coupling mechanism. The curvature spin of carbon is regarded as an overlapping state of σ‐ and π‐radical, which is identified by the inverse Laplace transform of pulse‐electron paramagnetic resonance. The growth mechanism of carbon spheres abiding by Kroto's model, is supported by the density functional theory study of thermodynamics and kinetics calculations. The solid carbon spheres present excellent catalytic behaviour of oxidation coupling of amines to form corresponding imines with the conversion of >99 %, selectivity of 98.7 %, and yield of 97.7 %, which is attributed to the predominantly curvature‐induced electron spin catalysis of carbon, supported by the calculation of oxygen adsorption energy. This work proposes a view of curvature‐induced spin catalysis of carbon, which opens up a research direction for curvature‐induced electron spin catalysis. [ABSTRACT FROM AUTHOR]

The structural characterization of proteins with a disorder requires a computational approach backed by experiments to model their diverse and dynamic structural ensembles. The selection of conformational ensembles consistent with solution experiments of disordered proteins highly depends on the initial pool of conformers, with currently available tools limited by conformational sampling. We have developed a Generative Recurrent Neural Network (GRNN) that uses supervised learning to bias the probability distributions of torsions to take advantage of experimental data types such as nuclear magnetic resonance J-couplings, nuclear Overhauser effects, and paramagnetic resonance enhancements. We show that updating the generative model parameters according to the reward feedback on the basis of the agreement between experimental data and probabilistic selection of torsions from learned distributions provides an alternative to existing approaches that simply reweight conformers of a static structural pool for disordered proteins. Instead, the biased GRNN, DynamICE, learns to physically change the conformations of the underlying pool of the disordered protein to those that better agree with experiments. [ABSTRACT FROM AUTHOR]

The heterogeneous photo-Fenton system using Fe-Co/γ-Al2O3 as a catalyst was applied in the study of sulfamethoxazole(SMX) degradation. The morphology, structure, elemental composition and metal valence distribution of Fe-Co/γ-Al2O3 were found to be relatively stable before and after the reaction. The highest SMX degradation efficiency and mineralization (The ratio of organic matter being oxidized to carbon dioxide and water) were obtained under the conditions of 15% Fe-Co loading rate, 1:1 mass ratio of Fe and Co, 1 g/L catalyst dosage, 1.5 mL 30% H2O2 dosage, 18 W UV lamp power and 60 min reaction time, which were 98% and 66%, respectively. Radical quenching experiments and electronic paramagnetic resonance (EPR) characterization revealed that ·OH played an important role in the degradation and mineralization SMX in the Fe-Co/γ-Al2O3 heterogeneous photo-Fenton system. Combined with the analysis of N, S and intermediate products, there may be three degradation pathways of SMX in the heterogeneous photo-Fenton system. This work provides a technical reference for realizing the efficient degradation and mineralization of SMX in a heterogeneous photo-Fenton reaction system. [ABSTRACT FROM AUTHOR]

Effects of xanthene dyes and aerosil nanoparticles on the structure and dynamic characteristics of the cross-linked polyurethane were investigated by the IR-spectroscopy, dynamic-mechanical analysis, and electronic paramagnetic resonance methods. Dye molecule presence causes self-association of urethane groups within polymer rigid segments, weaker interactions between urethane groups and flexible oligoether parts and increased oligoether mobility. Increased mobility of flexible segments by xanthene dyes provides the necessary beam strength due to compensating the nanofiller network effect. The most efficient polyurethane material in the radiation resistance is expected to be a polymer composite with the highest permeability and the lowest modulus of elasticity. [ABSTRACT FROM AUTHOR]

Two complexes (C6H9N2)2[CuCl4] (1) and (C5H6N2Cl)2[CuCl4] (2) have been synthesized and characterized by single‐crystal X‐ray diffraction which revealed that these phases are centrosymmetric and crystallize, respectively, in monoclinic and triclinic symmetries. The thermal properties of both complexes are investigated as well as the UV‐Vis spectroscopic, photoluminescence properties, electronic paramagnetic resonance and biological activities. The crystal packing of the two compounds is guided by N−H⋅⋅⋅Cl hydrogen bonds and offset π–π stacking interactions; these interactions contribute to the overall stabilization of the structures as they connect anions and cations together into a three‐dimensional network. In addition, the optimized molecular structure was calculated by the Density Functional Theory (DFT) method using the B3LYP function with the LanL2DZ basis set. Subsequently, the thermal behavior was studied by TGA/DTA analyses. Moreover, the optical properties were studied using optical absorption UV‐visible and photoluminescence (PL) spectroscopy. The analysis of the magnetic properties is studied by electronic paramagnetic resonance (EPR). Simultaneously, compound (1) exhibits a potential inhibitory effect against the key enzymes associated with diabetes, obesity, and hyperlipidemia. It demonstrates IC50 values of 0.21 μM and 0.32 μM against α‐amylase and lipase, respectively. Consequently, it emerges as a promising candidate for the treatment of diabetes and obesity. [ABSTRACT FROM AUTHOR]

Here, we combined magnetometry, multi‐frequency electronic paramagnetic resonance, and wave function based ab initio calculations to investigate magnetic properties of two high spin Co(II) complexes Co(BDPRP) (BDPRP=2,6‐bis((2‐(S)‐di(4‐R)phenylhydroxylmethyl‐1‐pyrrolidi‐nyl)methyl)pyridine, R=H for 8; R=tBu for 9). Complexes 8 and 9 featuring effective D3h symmetry were found to possess D=24.0 and 32.0 cm−1, respectively, in their S=3/2 ground states of 1e''dxz/yz41e'dxy/x2-y221a1'dz21 ${{\left(1{{\rm e}}^{{\rm { {^\prime}}}{\rm { {^\prime}}}}\right({d}_{xz/yz}\left)\right)}^{4}{\left(1{{\rm e}}^{{\rm { {^\prime}}}}\right({d}_{{xy/{x}^{2}-y}^{2}}\left)\right)}^{2}{\left(1{{\rm a}}_{1}^{{\rm { {^\prime}}}}\right({d}_{{z}^{2}}\left)\right)}^{1}}$. Ligand field analyses revealed that the low‐lying d‐d excited states make either positive or vanishing contributions to D. Hence, total positive D values were measured for 8 and 9, as well as related D3h high spin Co(II) complexes. In contrast, negative D values are usually observed for C3v congeners. In‐depth analyses suggested that lowering symmetry from D3h to C3v induces orbital mixing between 1edxz/yz ${1{\rm e}\left({d}_{xz/yz}\right)}$ and 2edxy/x2-y2 ${2{\rm e}\left({d}_{{xy/{x}^{2}-y}^{2}}\right)}$ and admixes excited state 4A21e→2e ${{}^{4}{{\rm A}}_{2}\left(1e\to 2e\right)}$ into the ground state. Both factors turn the total D value progressively negative with the increasing distance (δ) of the Co(II) center out of the equatorial plane. Therefore, δ determines the sign and magnitude of final D values of five‐coordinate trigonal bipyramidal S=3/2 Co(II) complexes as measured for a series of such species with varying δ. [ABSTRACT FROM AUTHOR]

Halophyte species represent valuable reservoirs of natural antioxidants, and, among these, Salicornia europaea stands out as a promising edible plant. In this study, young and old S. europaea leaves were compared for the content of bioactive compounds and antioxidant activity to assess changes in different growth phases; then, the potential protective effects against low-dose CCl4-induced toxicant-associated fatty liver disease (TAFLD) were investigated by administering an aqueous suspension of young leaves to rats daily for two weeks. Quantification of total and individual phenolic compounds and in vitro antioxidant activity assays (DPPH, FRAP, and ORAC) showed the highest values in young leaves compared to mature ones. Salicornia treatment mitigated CCl4-induced hepatic oxidative stress, reducing lipid peroxidation and protein carbonyl levels, and preserving the decrease in glutathione levels. Electronic paramagnetic resonance (EPR) spectroscopy confirmed these results in the liver and evidenced free radicals increase prevention in the brain. Salicornia treatment also attenuated enzymatic disruptions in the liver's drug metabolizing system and Nrf2-dependent antioxidant enzymes. Furthermore, histopathological examination revealed reduced hepatic lipid accumulation and inflammation. Overall, this study highlights Salicornia's potential as a source of bioactive compounds with effective hepatoprotective properties capable to prevent TAFLD. [ABSTRACT FROM AUTHOR]

The measurement of partial pressures of oxygen (O2) and carbon dioxide (CO2) is fundamental for evaluating a patient's conditions in clinical practice. There are many ways to retrieve O2/CO2 partial pressures and concentrations. Arterial blood gas (ABG) analysis is the gold standard technique for such a purpose, but it is invasive, intermittent, and potentially painful. Among all the alternative methods for gas monitoring, non-invasive transcutaneous O2 and CO2 monitoring has been emerging since the 1970s, being able to overcome the main drawbacks of ABG analysis. Clark and Severinghaus electrodes enabled the breakthrough for transcutaneous O2 and CO2 monitoring, respectively, and in the last twenty years, many innovations have been introduced as alternatives to overcome their limitations. This review reports the most recent solutions for transcutaneous O2 and CO2 monitoring, with a particular consideration for wearable measurement systems. Luminescence-based electronic paramagnetic resonance and photoacoustic sensors are investigated. Optical sensors appear to be the most promising, giving fast and accurate measurements without the need for frequent calibrations and being suitable for integration into wearable measurement systems. [ABSTRACT FROM AUTHOR]

Two new pentagon‐embedded carbo[11]helicenes have been designed and synthesized in a three‐step process, which are the first example of carbo[11]helicenes through the post‐functionalization of twistacene. TD‐DFT analyses indicate that both of them possess high enantiomerization barriers of 42.29 kcal/mol and 40.76 kcal/mol, respectively. They emit strong red fluorescence and can be chemically oxidized into stable cationic radicals upon addition of AgSbF6 evidenced by the bathochromic‐shifted absorption spectra and the appearance of electronic paramagnetic resonance (EPR) signals. In addition, such helical derivatives can be chosen as radiative cooling materials in a glass model house, and the maxima of 5.4 °C for the former and 6.5 °C for the latter are found in the comparative tests, which might be caused by the NIR reflective response. [ABSTRACT FROM AUTHOR]

Chromium-intercalated hexagonal Cr1∕3TaS2 possesses exotic properties, such as high-temperature magnetic soliton, crossover of critical behavior, and nontrivial magnetism. In this study, we employ the electron spin resonance (ESR) technique to modulate and study the chiral magnetic soliton lattice (CSL) in Cr1∕3TaS2 using microwave at X-band. The experimental results show that Cr1∕3TaS2 has a particularly strong microwave response when H ⊥ c but very weak feedback when H / / c , revealing an anisotropic microwave response. When H ⊥ c , the resonance peak at lower fields results from the surface barrier induced by the competition between Dzyaloshinsky–Moriya interaction, Zeeman energy, and exchange energy. The dominant resonance is caused by the ferromagnetic mode with the twisted region as the boundary condition, which transforms into a paramagnetic resonance above the phase transition temperature (TC). Furthermore, an unusual temperature dependence of ESR spectra is revealed. The crystalline electric field (CEF) excitation owing to large strong spin–orbit coupling results in the widening of the ESR linewidth above TC. Furthermore, an abrupt shift in the resonance field H r 2 and ESR linewidth Δ H P P 2 is observed around TC, which is attributed to a sudden change in spin-exchange interactions and magnetic anisotropy around TC, as Cr1∕3TaS2 was previously observed for spin interaction transition from strong anisotropic 3D-Ising type to isotropic 3D-Heisenberg magnetic interaction below TC. This work demonstrates that the ESR can detect the CSL state and investigate materials with nontrivial magnetism. [ABSTRACT FROM AUTHOR]

Unexpected benefits to the catalytic performance of materials often originate from the presence of surface defects. Here, novel D-penicillamine modified molybdenum oxide nanodots, with abundant oxygen vacancy defects, were fabrication by a mild, simple, and cost-effective method. Ultraviolet—visible (UV—Vis) absorption spectra analysis showed that the nanodots had peroxidase-like and catalase-like activities. The reactive oxygen species were probed by electronic paramagnetic resonance technique and spectroscopic methods, demonstrating that the nanodots also had oxidase-like activity. Interestingly, the peroxidase-like activity of nanodots was synergistically enhanced in the presence of ferrous ions or ferric ions. Remarkably, less than nanomolar levels of ferrous ions were required to display this phenomenon, meaning Fenton reagent acted as leverage. Based on this, a sensitive colorimetric and fluorescent dual-mode sensor for alendronate sodium was developed. The linear ranges for colorimetric and fluorescence analysis were 0.2–2.5 and 0.2–2.0 µM, with detection limits of 31.21 and 71.84 nM, correspondingly. The method has a simple large-scale material preparation process with higher sensitivity and shorter reaction time, which can inspire and enlighten the design of nanozyme sensors. [ABSTRACT FROM AUTHOR]

We explain a recent experimental observation that the time-resolved electron paramagnetic resonance spectra of an organic molecule for optical excitation within a highly absorbing region of the molecule has similar intensities to the spectra for optical excitation in a nonabsorbing region [D. L. Meyer et al., J. Phys. Chem. Lett. 8, 1677 (2017)]. We demonstrate that this phenomenon is due to an initial-state preparation effect of photoexcitation that leads to similar initial populations of triplet states for both optical excitation regions. Due to the low intersystem crossing rates, the initial triplet populations are not perturbed on the time scale of the experiment, so they determine the relative intensities of the paramagnetic resonance spectra. The effect is surprising given the weak spin-orbit interactions of organic molecules. Such initial-state preparation effects are likely to occur in systems where the intersystem crossing time scales are long compared to the time scale of the experiment. [ABSTRACT FROM AUTHOR]

Hexagonal molybdenite (2H-MoS2) is one of the most promising 2D semiconductors with enormous potential applications in electronic, optoelectronic, and spintronic devices. Its electrical properties are strongly influenced by impurities such as Arsenic and Rhenium but the mechanisms involved remain unknown. In this work, geological and commercial samples of 2H-MoS2 were investigated by neutron activation analysis. Arsenic, Rhenium, and other elements, were found in the mg/kg concentration range. Their possible role in the physical properties was investigated by electron paramagnetic resonance and Hall Effect measurements. Preliminary results suggest the influence of Arsenic and Rhenium in the electrical proprieties of the MoS2. [ABSTRACT FROM AUTHOR]

Highlights: A new Cu(II) paddle-wheel-like complex with vinylbenzoic acid was synthesized and characterized. The replacement of solvent molecules by water molecules from humid air at the open Cu2+ coordination sites of the complex should be explored further. A new Cu(II) paddle-wheel-like complex with 4-vinylbenzoate was synthesized using acetonitrile as the solvent. The complex was characterized by X-ray crystal diffraction, FT-IR, diffuse reflectance spectroscopy, thermogravimetric, differential scanning calorimetric, magnetic susceptibility, and electronic paramagnetic resonance analyses. The X-ray crystal diffraction analysis indicated that each copper ion was bound at an equatorial position to four oxygen atoms from the carboxylate groups of the 4-vinylbenzoate ligand in a square-based pyramidal geometry. The distance between the copper ions was 2.640(9) Å. The acetonitrile molecules were coordinated at the axial position to the copper ions. Exposure of the Cu(II) complex to humid air promoted the gradual replacement of the coordinated acetonitrile by water molecules, but the complex structure integrity remained. The EPR spectra exhibited signals attributed to the presence of a mixture of the monomeric (S = ½) and dimeric (S = 1) copper species in a possible 3:1 ratio. The magnetic studies revealed a peak at 50–100 K, which could be associated with the oxygen absorption capacity of the Cu(II)–vba complex. [ABSTRACT FROM AUTHOR]

The reaction of the 2,2′-azino-bis(3-ethylbenzothiazoline-6-sulfonate) free radical (ABTS●) with proteins (bovine serum albumin, blood plasma, egg white, erythrocyte membranes, and Bacto Peptone) leads not only to a reduction of ABTS● but also to the appearance of a purple color (absorption maximum at 550–560 nm). The aim of this study was to characterize the formation and explain the nature of the product responsible for the appearance of this color. The purple color co-precipitated with protein, and was diminished by reducing agents. A similar color was generated by tyrosine upon reaction with ABTS●. The most feasible explanation for the color formation is the addiction of ABTS● to proteins' tyrosine residues. The product formation was decreased by nitration of the bovine serum albumin (BSA) tyrosine residues. The formation of the purple product of tyrosine was optimal at pH 6.5. A decrease in pH induced a bathochromic shift of the spectra of the product. The product was not a free radical, as demonstrated by electrom paramagnetic resonance (EPR) spectroscopy. Another byproduct of the reaction of ABTS● with tyrosine and proteins was dityrosine. These byproducts can contribute to the non-stoichiometry of the antioxidant assays with ABTS●. The formation of the purple ABTS adduct may be a useful index of radical addition reactions of protein tyrosine residues. [ABSTRACT FROM AUTHOR]

In this study, the Ce-modified tea residue biochar (Ce-TBC) was successfully generated and applied to the biochar/persulfate system (Ce-TBC/PDS), the mechanism of the removal of tetracycline (TC) using Ce-TBC/PDS was elaborated. Under the optimal experimental conditions (Ce-TBC = 0.8 g L−1, PDS = 4 mM, TC = 10 mg L−1), the removal efficiency of TC was 91.28%, and after 5 cycles, the elimination rate of Ce-TBC/PDS still reached up to 80%. The mechanism of TC removal by Ce-TBC/PDS was analyzed by scanning electron microscopy (SEM), X-ray diffractometer (XRD), Fourier infrared transform spectrometer (FT-IR), and X-ray photoelectron spectrometer (XPS) characterization, and influence factor experiments. The results showed that the introduction of CeOx increased the oxygen vacancies on the TBC surface and promoted the interconversion between Ce3+ and Ce4+ for better activation of PDS and generation of active species. Free radical quenching experiments and paramagnetic resonance spectrometry (EPR) analysis showed that the non-radical pathway 1O2 played a dominant role in the Ce-TBC/PDS system. The present work provided an efficient means of PDS activator and recycling of tea waste. [ABSTRACT FROM AUTHOR]

The known methods for measuring the spin transport parameters in spin-valve structures are based on the Hanle effect, viz., electron spin precession in an external magnetic field and a decrease in the magnetoresistive signal. These methods make it possible to determine the spin relaxation time in the paramagnetic layer and the relative current polarization constant. We describe an alternative method of measuring in zero external magnetic field, which is based on the resonant increase in the magnetic susceptibility of the paramagnetic layer due to the paramagnetic resonance induced by the nonequilibrium magnetization due to the spin accumulation effect. The proposed method makes it possible to determine the absolute value of spin accumulation in a paramagnet, which can be used as a parameter for numerical solution of three-dimensional diffusion equations of spin transport. [ABSTRACT FROM AUTHOR]

We demonstrate high signal-to-noise electrically detected electron-nuclear double resonance measurements on fully processed bipolar junction transistors at room temperature. This work indicates that the unparalleled analytical power of electron-nuclear double resonance in the identification of paramagnetic point defects can be exploited in the study of defects within fully functional solid-state electronic devices. [ABSTRACT FROM AUTHOR]

To improve the photocatalytic performance of Mn0.6Zn0.4Fe2O4 (MZFO) and ZnIn2S4 (ZIS) for organic pollutants, the p-n MZFO@ZIS heterojunctions with different weight percentage (10 ~ 40%) of MZFO are constructed from spent batteries and added indium ion via a green bioleaching and hydrothermal method. Structural, optical, and photocatalytic properties for the heterojunctions are investigated systematically by XRD, FT-IR, SEM–EDX, TEM, BET, VB-XPS, UV–vis DRS, PL, etc. The results confirm that p–n junction significantly improves the visible light adsorption and the separation efficiency of photogenerated carriers. Specifically, MZFO-25%@ZIS shows the highest photodegradation performance toward Congo red (CR), and its reactive kinetic constant is about 9.6, 7.8, and 7.0 times higher than that of P25 TiO2, MZFO, and ZIS, respectively, and MZFO-25%@ZIS still possesses a high reusability and simple magnetic separation after 5 cycles of reuse. The radical trapping experiments and electronic paramagnetic resonance (EPR) tests show that ·O2−, ·OH, and h+ are the most important active substance for degrading CR. The pathways for the CR degradation are further proposed based on the intermediate analysis. DFT + U calculations confirm that the high charge density of Zn–O, Fe–O, and Zn–S bonds in the MZFO and ZIS molecules provides the electrons for the sufficient production of free radicals. This work also provides a novel high value-added strategy for the green utilization of spent batteries. [ABSTRACT FROM AUTHOR]

We report the magnetic, electrical, thermoelectric, and magnetic resonance properties of the Mn-site doped manganite LaMn0.94Mo0.06O3. This sample undergoes an insulator-metal transition around 235 K, near the ferromagnetic Curie temperature (TC = 237 K) in zero external magnetic field. On the other hand, thermopower exhibits a maximum at TS = 258 K, which is 23 K higher than TC. This discrepancy is attributed to nucleation of ferromagnetic clusters (Griffiths phase) above TC, which is supported by the deviation of inverse susceptibility from Curie-Weiss from linear behavior below 270 K and non-linear field dependence of magnetization. The magnetic resonance spectra shows both paramagnetic and ferromagnetic resonance signals between 240 and 260 K. It is suggested that the ferromagnetic clusters enlarge in size with lowering temperature and percolate leading to long-range ferromagnetism and metallicity. [ABSTRACT FROM AUTHOR]

The structural, electronic and magnetic properties of high purity nanostructured CeO 2 powders were investigated under various reducing atmospheres. By performing in situ experiments, it was demonstrated that the appearance of oxygen vacancies promotes a paramagnetic behaviour in an initially diamagnetic oxide. This conclusion is inferred through a careful and detailed correlation between the magnetic measurements and the analysis of the electronic properties, obtained by X-ray absorption experiments under different atmospheres. After exposing the CeO 2 powders to a reducing atmosphere, a residual state is obtained and the samples continue to exhibit a paramagnetic behaviour characterized by lower susceptibility values than those obtained during the in situ experiments. The results of ex situ Electronic Paramagnetic Resonance (EPR) measurements at room temperature further support the finding of paramagnetic behaviour in all the samples. EPR was used to characterize the electronic defects ascribed to intrinsic oxygen vacancies already present in the "as prepared" samples and extrinsic oxygen vacancies originated during the reducing treatments. The quasi-linear dependence observed between the intensity of the EPR signal characteristic of annealed samples and the duration of the corresponding reducing treatment suggests that there is a direct correlation between the paramagnetic residual state and the creation of extrinsic oxygen vacancies that occurs at high temperature under reducing atmosphere. [ABSTRACT FROM AUTHOR]

We report the magnetic, electrical, thermoelectric, and magnetic resonance properties of the Mn-site doped manganite LaMn0.94Mo0.06O3. This sample undergoes an insulator-metal transition around 235 K, near the ferromagnetic Curie temperature (TC = 237 K) in zero external magnetic field. On the other hand, thermopower exhibits a maximum at TS = 258 K, which is 23 K higher than TC. This discrepancy is attributed to nucleation of ferromagnetic clusters (Griffiths phase) above TC, which is supported by the deviation of inverse susceptibility from Curie-Weiss from linear behavior below 270 K and non-linear field dependence of magnetization. The magnetic resonance spectra shows both paramagnetic and ferromagnetic resonance signals between 240 and 260 K. It is suggested that the ferromagnetic clusters enlarge in size with lowering temperature and percolate leading to long-range ferromagnetism and metallicity. [ABSTRACT FROM AUTHOR]

Gradient of spin accumulation in spintronic devices such as lateral spin-valves allows to generate pure spin-current without charge-current. Spin accumulation is an out-of-equilibrium magnetization in which thermal fluctuations can occur. These fluctuations may constitute a source of noise in lateral spin-valve structures. In this study, the thermally induced fluctuations of the vector of spin-accumulation were investigated theoretically in diffusive regime. It is shown that paramagnetic resonance may arise in the spin-current carrying channel due to electron-electron interactions and exchange splitting induced by the spin-accumulation. This leads to an effect that was not previously considered: resonant increase of the magnetic susceptibility of the paramagnetic channel material and an associated decrease in signal-to-noise ratio around the resonance frequency. Frequency dependence of the magnetic susceptibility and signal-to-noise ratio were calculated analytically in the case of a specific T-shaped lateral spin-valve structures. It was shown however that this noise caused by thermally induced fluctuations in spin-accumulation is generally negligible in comparison to other sources of noise present in lateral spin-valves such as Johnson noise or thermal fluctuations of magnetization in the magnetic electrodes. [ABSTRACT FROM AUTHOR]

The impact of different storage conditions on the generation of radicals was evaluated through electronic paramagnetic resonance (EPR) detection of spin adducts based on the Fenton reaction, after an accelerated aging of beer (55 °C for 150 min). The different conditions applied, namely storage time and temperature, have clearly demonstrated to affect the beer oxidative stability. The greater endogenous antioxidant potential (higher lag phase values) observed for fresh beers is due to the higher levels of SO2. In contrast, the higher levels of radicals observed after 150 min of accelerated aging are related to the higher content of iron in fresh beers. Lower levels of SO2 and iron found in aged beers are therefore related to the lower endogenous antioxidant potential and the lower levels of radicals after 150 min of accelerated aging, respectively. According to our model for shelf-life prediction, the best-before date of beer can be reduced from 6 months, if stored at 20 °C, to as little as 9 days if it is stored at 37 °C. [ABSTRACT FROM AUTHOR]

In this study, we measured translational water diffusion selectively along symplast pathway through plasmodesmata in maize roots, and the effective plasmodesmata permeability coefficient (P) was determined using a nuclear magnetic resonance (NMR) spin echo method. Measuring of water transport selectively along the plant root plasmodesmata was achieved with paramagnetic complexes (PCs) of high relaxation efficiency. PCs penetrate into the intercellular space of root tissue, but not into cells, and accelerate the magnetic relaxation processes of intercellular water, thereby excluding the contribution of intercellular water to the registered NMR diffusion echo attenuation. In result, NMR control of translational diffusion can be applied to the signal of the water moving along the symplast pathway through plasmodesmata, where the PCs do not penetrate. Diethylenetriaminepentaacetic acid (GdDTPA), Mn2+-trans-1,2-diaminocyclohexane-N,N,N′,N′-tetraacetic acid (MnDCTA), and GdCl 3 were used as PCs. An increase in the PCs concentration led to a side effect in the form of a varying decrease in diffusive water transport in the roots. The P was determined by extrapolating the concentration dependence to zero concentration of PCs. Among the PCs studied, MnDCTA had the least side effects on the water transport when the concentration dependence was linear. When MnDCTA was used, the P accounted for 30–35% of the total cell water permeability (by transmembrane and symplast pathways). The rate of water flow along the plasmodesmata in the approximation of the piston mode of flow along the linear cell chain was estimated to range from 4.5 × 10−7 to 8.8 × 10−7 m/s. • Water transport along plant root plasmodesmata by NMR and paramagnetics was studied. • Paramagnetic complexes can reduce cell-to-cell water transport in plant roots. • The rate of water flow through plasmodesmata was calculated. [ABSTRACT FROM AUTHOR]

Gradient of spin accumulation in spintronic devices such as lateral spin-valves allows to generate pure spin-current without charge-current. Spin accumulation is an out-of-equilibrium magnetization in which thermal fluctuations can occur. These fluctuations may constitute a source of noise in lateral spin-valve structures. In this study, the thermally induced fluctuations of the vector of spin-accumulation were investigated theoretically in diffusive regime. It is shown that paramagnetic resonance may arise in the spin-current carrying channel due to electron-electron interactions and exchange splitting induced by the spin-accumulation. This leads to an effect that was not previously considered: resonant increase of the magnetic susceptibility of the paramagnetic channel material and an associated decrease in signal-to-noise ratio around the resonance frequency. Frequency dependence of the magnetic susceptibility and signal-to-noise ratio were calculated analytically in the case of a specific T-shaped lateral spin-valve structures. It was shown however that this noise caused by thermally induced fluctuations in spin-accumulation is generally negligible in comparison to other sources of noise present in lateral spin-valves such as Johnson noise or thermal fluctuations of magnetization in the magnetic electrodes. [ABSTRACT FROM AUTHOR]

Linked to Alzheimer's disease (AD), amyloids and tau-protein are known to contain a large number of cysteine (Cys) residues. In addition, certain levels of some common biogenic thiols (cysteine (Cys), homocysteine (Hcy), glutathione (GSH), etc.) in biological fluids are closely related to AD as well as other diseases. Therefore, probes with a selective interaction with the above-mentioned thiols can be used for the monitoring and visualizing changes of (bio)thiols in the biological fluids as well as in the brain of animal models of Alzheimer's disease. In this study, new Eu(III), Tb(III), Gd(III) and Sm(III) complexes of 2,2′-bipyridine ligands containing TEMPO fragments as receptor units for (bio)thiols are reported. The presence of free radical fragments of the ligand in the complexes was proved by using the electronic paramagnetic resonance (EPR) method. Among all the complexes, the Eu(III) complex turned out to be the most promising one as luminescence- and spin-probe for the detection of biogenic thiols. The EPR and fluorescent titration methods showed the interaction of the resulting complex with free Cys and GSH in solution. To study the practical applicability of the probes for the monitoring of AD in-vivo, by using the above-mentioned Eu(III)-based probe, the staining of the brain of mice with amyloidosis and Vero cell cultures supplemented with the cysteine-enriched medium was studied as well as the fluorescence titration of Bovine Serum Albumin, BSA (as the model for the thiol moieties containing protein), was carried out. Based on the results of fluorescence titration, the formation of a non-covalent inclusion complex between the above-mentioned Eu(III) complex and BSA was suggested. [ABSTRACT FROM AUTHOR]

In this work, we theoretically investigate the local structure and electronic paramagnetic resonance (EPR) parameters (g-factors gi and A-constants Ai, i = //, ⊥) of tetragonal Cu2+ centers in phosphate glasses (xCuO⋅(1 – x)[2P2O5⋅Na2O] (0.5< x < 5 mol %)) with the aid of the three-order perturbation formulae of these parameters for 3d9 ions in tetragonally distorted tetrahedra based on the cluster approach. In our calculations, both contributions to EPR parameters from the spin-orbit (SO) coupling interactions of the central Cu2+ ions and the ligand orbital and SO coupling interactions are included. The crystal-field parameters related to the splitting of d-orbitals are calculated from the superposition model and the local structures of the studied Cu2+ centers in the glasses. Based on the calculations, the local bond angle is found to be about 3.78° larger than that of the ideal tetrahedral site, resulting in a slightly compressed ligand tetrahedron. The relative contributions to the g-factors from the ligand orbital and SO coupling interactions are more important than those from the third-order perturbation terms. The theoretical results show good agreement with the experimental values. The signs and the less anisotropy (ΔA = |A//| – |A⊥|) of A-constants for the tetrahedral Cu2+ centers are discussed. [ABSTRACT FROM AUTHOR]

Bismuth ferrite particles (BiFeO3/BFO) were successfully prepared by hydrothermal method with bismuth nitrate pentahydrate and iron nitrate nonahydrate as raw materials. The effects of environmental alkalinity, concentration of mineralizer (NaOH), hydrothermal reaction temperature and time on the crystal structure, morphology and catalytic performance of bismuth ferrite particles were investigated. Furthermore, bismuth ferrite particles were surface modified to prepare sample BFO-PVP and BFO-CTAB with polyvinylpyrrolidone (PVP) and cetyl trimethyl ammonium bromide (CTAB), respectively. The samples were characterized by field emission scanning electron microscope (FE-SEM), X-ray diffractometer (XRD), Fourier transform infrared spectrometer ( FT-IR ), X-ray photoelectron spectrometer (XPS) and paramagnetic resonance spectrometer (ESR/EPR). The results showed that high crystallinity bismuth ferrite particles with single phase perovskite structure could be obtained with the pH = 12 of the precursor solution, 3 mol/L of mineralizer (NaOH) by hydrothermal reaction at 200 °C for 9 h, and they showed uniform morphology and good dispersibility. When the addition amount of PVP and CTAB was 0. 5 g/L and 1. 0 g/L, respectively, the modified bismuth ferrite displayed the best Fenton-like degradation effect on cationic rhodamine B. The reaction rate constants were 1. 8 times and 1. 6 times of unmodified bismuth ferrite, respectively. [ABSTRACT FROM AUTHOR]

[Display omitted] • Metal encapsulated inside carbon aerogels were similar in physicochemical property. • The activity followed Co@CS>Fe@CS>Ni@CS>Zn@CS in heterogeneous EP. • Co@CS and Fe@CS exerted the superior activity for sole O 3 and H 2 O 2 decomposition. • The addition of M@CS enhanced the generation of · OH/ · O 2 −/1O 2 in EP. • M@CS/EP showed good applicability to various pollutants and real water. Transition metals have critical influences on the generation of reactive oxygen species in activating O 3 and H 2 O 2 , as the binary oxidant sources in electro-peroxone (EP). To evaluate the catalytic activity of different metals and reveal the reactive oxygen species generation in heterogeneous EP, series of metals encapsulated inside carbon aerogel spheres (M@CS, M=Fe, Co, Ni, Zn) were fabricated for strengthening EP. Atrazine was used as model pollutant due to its low reactivity with O 3 , and the abatement trends followed Co@CS > Fe@CS > Ni@CS > Zn@CS. Co@CS exhibited the superior catalytic activity with maximum metal active site utilization (1.28 × 103 min-1 mol-1 per mole Co atom sites at pH 7) and minimum electric energy consumption (0.106 kWh/m3-log). The catalytic activity of M@CS was related to the adsorption energies for O 3 and H 2 O 2 (Fe@CS > Co@CS > Ni@CS > Zn@CS) and the graphitization degree (Co@CS > Fe@CS > Ni@CS > Zn@CS). Verified by theoretical calculation and in-situ Fourier transformed infrared, the metal effectively promoted the adsorption and decomposition of O 3 and H 2 O 2 into the surface oxygen intermediates, finally generating · OH/ · O 2 -/1O 2. The carbon layer was conducive to the reduction of internal metal, ensuring catalyst durability. Electronic paramagnetic resonance and kinetic model revealed the occurrence, ratio and transient concentration of · OH/ · O 2 -/1O 2 in M@CS/EP. M@CS/EP showed good performance for pollutant removal in coexistence of anions, humic acid and real water. This study provides guidance for selecting the metal–carbon catalyst in heterogeneous EP. [ABSTRACT FROM AUTHOR]

We present a state interaction spin-orbit coupling method to calculate electron paramagnetic resonance g-tensors from density matrix renormalization group wavefunctions. We apply the technique to compute g-tensors for the TiF3 and CuCl 4 2 − complexes, a [2Fe–2S] model of the active center of ferredoxins, and a Mn4CaO5 model of the S2 state of the oxygen evolving complex. These calculations raise the prospects of determining g-tensors in multireference calculations with a large number of open shells. [ABSTRACT FROM AUTHOR]

The development of innovative fibrous materials with valuable multifunctional properties based on biodegradable polymers and modifying additives presents a challenging direction for modern materials science and environmental safety. In this work, high-performance composite fibrous materials based on semicrystalline biodegradable poly-3-hydroxybutyrate (PHB) and natural iron-containing porphyrin, hemin (Hmi) were prepared by electrospinning. The addition of Hmi to the feed PHB mixture (at concentrations above 3 wt.%) is shown to facilitate the electrospinning process and improve the quality of the electrospun PHB/Hmi materials: the fibers become uniform, their average diameter decreases down to 1.77 µm, and porosity increases to 94%. Structural morphology, phase composition, and physicochemical properties of the Hmi/PHB fibrous materials were studied by diverse physicochemical methods, including electronic paramagnetic resonance, optical microscopy, scanning electron microscopy, and energy-dispersive X-ray spectroscopy, elemental analysis, differential scanning calorimetry, Fourier-transformed infrared spectroscopy, mechanical analysis, etc. The proposed nonwoven Hmi/PHB composites with high porosity, good mechanical properties, and retarded biodegradation due to high antibacterial potential can be used as high-performance and robust materials for biomedical applications, including breathable materials for wound disinfection and accelerated healing, scaffolds for regenerative medicine and tissue engineering. [ABSTRACT FROM AUTHOR]

Copyright of CT Theory & Applications is the property of Editorial Department of CT Theory & Applications and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Template‐assisted synthesis of well‐defined polynuclear clusters remains a challenge for [M4] square planar topologies. Herein, we present a tetraamine scaffold RL(NH2)4, where L is a rigidified resorcin[4]arene, to direct the formation of C4‐symmetric RL(NH)4Cu4 clusters with Cu−Cu distances around 2.7 Å, suggesting metal‐metal direct interactions are operative since the sum of copper's van der Waals radii is 2.8 Å. DFT calculations display HOMO to HOMO‐3 residing all within a 0.1 eV gap. These four orbitals display significant electron density contribution from the Cu centers suggesting a delocalized electronic structure. The one‐electron oxidized [Cu4]+ species was probed by variable temperature X‐band continuous wave‐electron paramagnetic resonance (CW‐EPR), which displays a multiline spectrum at room temperature. This work presents a novel synthetic strategy for [M4] clusters and a new platform to investigate activation of small molecules. [ABSTRACT FROM AUTHOR]

Objective: Blood oxygenation can be measured using magnetic resonance using the paramagnetic effect of deoxy-haemoglobin, which decreases the T 2 relaxation time of blood. This T 2 contrast has been well characterised at the B 0 fields used in MRI (1.5 T and above). However, few studies have characterised this effect at lower magnetic fields. Here, the feasibility of blood oximetry at low field based on T 2 changes that are within a physiological relevant range is explored. This study could be used for specifying requirements for construction of a monitoring device based on low field permanent magnet systems. Methods: A continuous flow circuit was used to control parameters such as oxygen saturation and temperature in a sample of blood. It flowed through a variable field magnet, where CPMG experiments were performed to measure its T 2 . In addition, the oxygen saturation was monitored by an optical sensor for comparison with the T 2 changes. Results: These results show that at low B 0 fields, the change in blood T 2 due to oxygenation is small, but still detectable. The data measured at low fields are also in agreement with theoretical models for the oxy-deoxy T 2 effect. Conclusion: T 2 changes in blood due to oxygenation were observed at fields as low as 0.1 T. These results suggest that low field NMR relaxometry devices around 0.3 T could be designed to detect changes in blood oxygenation. [ABSTRACT FROM AUTHOR]

Changes in the structure of phyllosilicate microparticles of submicron fractions of polymineral clay with an average size of 290 nm, as well as changes in the positions of impurity ions of transition metals in the crystal lattice, were studied by X-ray diffraction analysis, Fourier transform infrared spectroscopy, and high-resolution electron paramagnetic resonance spectroscopy. The main composition of microparticles included clinochlore, montmorillonite, calcite, and quartz. Structural transformations were stimulated by heating the samples to 1200 K at a rate of 10 K/min. A decrease in the number of crystal structures of microparticles was recorded due to the amorphization of montmorillonite, the decomposition of calcite, and the formation of sillimanite. Structural rearrangements of crystal cells containing impurity paramagnetic ions Fe3+ and Mn2+ in submicron particles of clinochlore and montmorillonite, accompanied by displacements and changes in the chemical bonds of these ions, were recorded by the ion-electron paramagnetic resonance method. It is shown that when microparticles were heated to 1200 K, the impurity paramagnetic ions of transition metals did not go beyond their crystal cells. [ABSTRACT FROM AUTHOR]

Peat humic acids are well known for their wide range of biological effects which can be attributed to the complex chemical structure of naturally occurring humic substances. One of the promising tools is an ontology-based quantitative analysis of the relationship between physical and chemical parameters describing a chemical structure of peat humic acids and their biological activity. This article demonstrates the feasibility of such an approach to estimate the antioxidant and cell protective properties of the peat humic acids. The structural parameters of the peat humic acids were studied by electronic, fluorescence, infrared, 13C-NMR spectroscopy, titrimetric analysis, elemental C,H,N, and O- analysis, and gel chromatography. Antioxidant and antiradical activities were assessed by physicochemical methods of analysis: electronic paramagnetic resonance, cathodic voltammetry, ABTS•+ scavenging, assay of DPPH radical-scavenging activity, assay of superoxide radical-scavenging activity, iron chelating activity, and scavenging of hydroxyl radicals. Cytoprotective activity was evaluated by the neutral red-based cytotoxicity test in 3T3-L1 cell culture in a wide range of concentrations. Assessment of intracellular ROS production was carried out using a 2,7-dichlorodihydrofluoresceindiacetate (DCFDA) fluorescent probe. Intracellular ROS production was induced using two common prooxidants (tert-butyl hydroperoxide, Fe2+ ions). We suggested an ontology-based model for the antioxidant and cytoprotective activity of humic acids based on experimental data and numerical models. This model establishes the way to further research on the biological effects of humic acids and provides a useful tool for numerical simulation of these effects. Remarkable antioxidant and cell protective activity of humic acids makes them a promising natural source of new pharmaceutical substances that feature a wide range of biological effects. [ABSTRACT FROM AUTHOR]

The room-temperature magnetic resonance spectra of metal–insulator (CoFeB)x(LiNbO3)100 –x and (CoFeB)x(Al2O3)100 –x nanogranular composite films with various ferromagnetic metallic phase contents x near the percolation threshold are investigated. The systems under study are characterized by a high concentration of paramagnetic ions dispersed in an insulator matrix between ferromagnetic granules. In addition to a usual ferromagnetic resonance signal, these films are found to exhibit an additional absorption peak in weak fields. In contrast to the usual ferromagnetic resonance excited by a transverse high-frequency magnetic field, the additional peak demonstrates a weak dependence of its amplitude on the resonance excitation geometry. The position of this peak depends on the composition of the system, the resonance excitation frequency (f = 7–38 GHz), and the magnetic field orientation with respect to the film plane. This behavior is associated with the paramagnetic resonance of Fe3+ ions, which are present in the insulator matrix and interact with ferromagnetic granules. [ABSTRACT FROM AUTHOR]

In this correspondence, we deduce the non-parabolic band dispersion within the framework of effective mass representation (EMR) using k → ⋅ π → perturbation theory in the presence of s.o interaction, magnetic impurity and external magnetic field. We measure the electronic parameters like Fermi energy, density of states, effective g factor and effective mass etc. in p-type S n 1 − x E u x T e by taking into account a 6-level band structure with normal and bumped band edges. In the study, we use the experimental and simulated band gap values as functions of E u + 2 impurity and temperature. Apart from the general trend, the electronic parameters exhibit extreme behaviour near the band inversion point x = 0. 020 at T=300 K (Nayak et. al.2023), but in the range of impurity concentration and temperature considered; from x = 0. 0005 to x = 0. 001 and T=1.5 K to T=300 K, the behaviour is normal. Again, we follow the expression for spin-electron paramagnetic resonance (EPR) shift (P s) where the perturbation expansion of Green's function is used in the presence of the above-mentioned interactions. To get around the problem of loss of translational symmetry in the presence of the magnetic field, Green's function is redefined in terms of Peierl's phase factor. Here we have made an extensive study of the shift of E u + 2 ion in p-type S n 1 − x E u x T e for several impurity concentrations from x = 0. 0005 to x = 0. 001 in the temperature range T=1.4 K to T=300 K. Lastly, we analyze the EPR shift and other electronic parameters and their anisotropies in p-type S n 1 − x E u x T e as functions of carrier concentration and E u impurity from T = 1. 5 K to T = 300 K. We report the EPR shift is 2. 97 × 1 0 − 3 at T=300 K and 3. 31 × 1 0 − 3 at T=1.5 K with anisotropy at p = 5 × 1 0 20 cm − 3 in contrast to the experimental observation of + (3. 4 ± 0. 4) × 1 0 − 3 in the same system. The discrepancy is attributed to the reduction in the density of available states at Fermi energy at the L-band caused by the simultaneous rise in that at the Σ − band noticeable particularly at/above high hole concentrations p ≥ 5 × 1 0 20 cm − 3 . [Display omitted] • The carrier dependent spin EPR shift is 3. 31 × 1 0 − 3 as compared to the experimental finding + (3. 4 ± 0. 4) × 1 0 − 3 at T=1.5 K. • The shift is attributed to the strong spin-orbit interaction. • The shift is quite remarkable at low temperatures because of strong spin-spin correlation. • The EPR shift does not depend on the impurity concentration implying no electron bottleneck effect existing at all in the system. • The presence of strong spin-orbit interaction makes this material a good choice for spintronics application. [ABSTRACT FROM AUTHOR]

The magnetic properties of hexagonal (Mo0.5Mn0.5)2GaC MAX phase synthesized as epitaxial films on MgO (111) substrates with the c-axis perpendicular to the film plane are presented. The analysis of temperature-dependent ferromagnetic resonance (FMR) and magnetometry data reveals a ferro- to paramagnetic phase transition at 220 K. The electrical transport measurements at 5K show a negative magnetoresistance of 6% in a magnetic field of 9 T. Further analysis confirms the spin-dependent scattering of charge carriers in this layered material. A small perpendicular (c-axis) magnetocrystalline anisotropy energy density (MAE) of 4.5 kJ/m³ at 100K was found using FMR. Accordingly, (Mo0.5Mn0.5)2GaC behaves similar to the (Cr0.5Mn0.5)2GaC MAX phase as a soft magnetic material. The density functional theory calculations reveal that the sign and the amplitude of the MAE can be very sensitive to (Mo0.5Mn0.5)2GaC lattice parameters, which may explain the measured soft magnetic properties [ABSTRACT FROM AUTHOR]

The mechanism behind radiophotoluminescence (RPL) emission in Ag-doped alkali-phosphate glass remains unclear. To contribute to resolving this issue, the authors measured and analyzed the temporal change of electron spin/paramagnetic resonance (ESR) spectrum of a recently developed, weather-resistant RPL glass, named "SAPANS," after irradiation with X-rays. As a result, a continuous gradual increase in Ag2+-derived signals was observed even at four weeks post-irradiation, which corresponded well with the time build-up pattern of the RPL of SAPANS. In contrast, the signals derived from phosphorous-oxygen-hole centers (POHC) rapidly decreased over a few days. The peaks of Ag0 and Ag 2 + were not successfully separated from the ESR spectra because of the possible overlap of unidentified peaks, which implies a complex mechanism of RPL-center formation in Ag-doped alkali-phosphate glass that requires further investigation. • Temporal changes in the post-irradiation ESR spectrum of a recently developed RPL glass (SAPANS) were analyzed. • The Ag2+ signal gradually increased even at four weeks, which was similar to the time build-up pattern of RPL. • The signals from the phosphorus-oxygen-hole centers (POHC) sharply decreased over three days. [ABSTRACT FROM AUTHOR]

Glycated human serum albumin (gHSA) undergoes conformational changes and unfolding events caused by free radicals. The glycation process results in a reduced ability of albumin to act as an endogenous scavenger and transporter protein in diabetes mellitus type 2 (T2DM) patients. Astaxanthin (ASX) in native form and complexed with metal ions (Cu2+ and Zn2+) has been shown to prevent gHSA from experiencing unfolding events. Furthermore, it improves protein stability of gHSA and human serum albumin (HSA) as it is shown through molecular dynamics studies. In this study, the ASX/ASX-metal ion complexes were reacted with both HSA/gHSA and analyzed with electronic paramagnetic resonance (EPR) spectroscopy, rheology and zeta sizer (particle size and zeta potential) analysis, circular dichroism (CD) spectroscopy and UV-Vis spectrophotometer measurements, as well as molecular electrostatic potential (MEP) and molecular docking calculations. The addition of metal ions to ASX improves its ability to act as an antioxidant and both ASX or ASX-metal ion complexes maintain HSA and gHSA stability while performing their functions. [ABSTRACT FROM AUTHOR]

The magnetic and some physicochemical properties of glasses based on barium-borosilicate eutectic doped with iron and lithium oxides were studied. The magnetic permeability increases with increasing content of Fe2O3. The character of magnetic permeability remains unchanged when Fe2O3 and Li2O are introduced simultaneously. The formation of structural motifs of barium hexaferrite in glass is responsible for magnetic properties. According to EPR data, some iron ions are present in tetrahedral coordination, incorporating into the structural mesh of the glass, and the others in octahedral coordination, acting as a modifier. [ABSTRACT FROM AUTHOR]

In this work, we theoretically study electronic paramagnetic resonance (EPR) parameters (g-factors and A-constants) of the rhombic Cu2 + center in Bis(L-asparaginato)zinc(II) crystal by using the high-order perturbation formulae for these parameters of d9 ion in rhombic octahedral environment from the cluster approach. In these formulae, the contribution to EPR parameters from the ligand orbital and spin–orbit coupling (SO) interactions for the studied Cu2+ center are considered in view of strong covalency. The energy splittings related to the optical absorption spectra are calculated by the superposition model and the local structure of the studied center. On the basis of the studies, the local structure of the center is slightly different from that of the host site due to the Jahn–Teller effect. The calculated results (EPR parameters and optical absorption band positions) are in better agreement with the experimental values than those of previous works. [ABSTRACT FROM AUTHOR]

Zinc oxide arouses considerable interest since it has many applications—in microelectronics, environmental decontaminations, biomedicine, photocatalysis, corrosion, etc. The present investigation describes the green synthesis of nanosized ZnO particles using a low-cost, ecologically friendly approach compared to the classical methods, which are aimed at limiting their harmful effects on the environment. In this study, ZnO nanoparticles were prepared using an extract of Mentha arvensis (MA) leaves as a stabilizing/reducing agent, followed by hydrothermal treatment at 180 °C. The resulting powder samples were characterized by X-ray diffraction (XRD) phase analysis, infrared spectroscopy (IRS), scanning electron microscopy (SEM), and electron paramagnetic resonance (EPR). The specific surface area and pore size distribution were measured by the Brunauer–Emmett–Taylor (BET) method. Electronic paramagnetic resonance spectra were recorded at room temperature and at 123 K by a JEOL JES-FA 100 EPR spectrometer. The intensity of the bands within the range of 400–1700 cm−1 for biosynthesized ZnO (BS-Zn) powders decreased with the increase in the Mentha arvensis extract concentration. Upon increasing the plant extract concentration, the relative proportion of mesopores in the BS-Zn samples also increased. It was established that the photocatalytic performance of the biosynthesized powders was dependent on the MA concentration in the precursor solution. According to EPR and PL analyses, it was proved that there was a presence of singly ionized oxygen vacancies (V0+) and zinc interstitials (Zni). The use of the plant extract led to changes in the morphology, phase composition, and structure of the ZnO particles, which were responsible for the increased photocatalytic rate of discoloration of Malachite Green dye. [ABSTRACT FROM AUTHOR]

Saffron (Croccus sativus) is a unique plant, valued all over the world. Considered one of the most expensive and noble spices. The properties of saffron were already known to the ancients, who not only added saffron to dishes and drinks, dyed fabrics with it, but also used it for health-promoting purposes. This plant is an excellent digestive aid, improving mood and appetite. Many scientific studies have also demonstrated its antidepressant, anticonvulsant, anticancer, antibacterial and antioxidant properties. Due to the wide application of this plant material, different origin, or storage time, it is important to verify the raw material in terms of its composition and properties. Hence the search for fast, non-destructive analytical methods that allow for raw material control. The article presents a qualitative analysis of the main bioactive compounds of saffron: crocin, picrocrocin and safranal using three spectroscopic techniques: UV-Vis spectroscopy, solid state nuclear magnetic resonance (1 H MAS and 13C CPMAS NMR) and nuclear paramagnetic resonance (EPR). The material was also analyzed for the antioxidant properties of saffron using the DPPH free radical scavenging test. The test was carried out on fresh material and after the material’s aging period-(UV radiation). Based on the obtained results, it was found that for the qualitative analysis of the tested samples it is advisable to use several analytical methods to obtain a complete picture. The ¹H MAS NMR spectra recorded for the powder samples distinguished the samples based on compounds with mobile aliphatic chains. On the other hand, the analysis of 13C CPMAS NMR spectra enables the differentiation of samples and the identification of the main components (aromatic rings, sugars, or carbonyl groups). The use of characteristic absorption bands for the main components of saffron can be the basis for determining the quality of the tested plant material. The analysis carried out with the use of the DPPH radical showed that saffron has high antioxidant properties, the effect of UV radiation reduces them by an average of 50%. [ABSTRACT FROM AUTHOR]

Iron- and copper-containing oxide catalysts have been synthesized by sol-gel technology with auto combustion using organic reagents - citric acid, glycine, urea as a complexing agent and "fuel"; studied their activity in the oxidation of carbon monoxide to dioxide. The obtained samples were characterized by the methods of X-ray powder diffraction, infrared spectroscopy and electronic paramagnetic resonance, the texture characteristics of these samples was determined by measuring the specific surface area. It is shown that, regardless of the preparation method, all synthesized samples are mixtures of iron oxides Fe2O3, copper CuO, and copper ferrite CuFe2O4. It was found that the nature of the organic reagent affects the catalytic activity of the synthesized catalysts. On a catalyst with a Cu:Fe=1:1 ratio, prepared by the sol-gel method with auto combustion using urea, the complete conversion of CO is achieved at 130°C. The same catalyst, synthesized with citric acid, is active at 250°C and on a catalyst prepared using glycine, complete conversion of CO occurs at a higher temperature of 350°C. It is assumed that the different nature of combustion leads to the formation of different surface morphology and texture, which ultimately determines the catalytic activity. Thus, the most catalytically active sample was obtained using urea as a "fuel" has a higher specific surface area (25 m² / g) than the other two samples (for the samples obtained with citric acid and glycine, the specific surface area is 9 m² / g and 5.8 m² / g, respectively). [ABSTRACT FROM AUTHOR]

The review is focused on the key achievements in the development of the synthetic approaches to the tris(tetrathiaaryl)methyl radicals. The properties and promising applications of these radicals are also considered. [ABSTRACT FROM AUTHOR]

We report on a defect related luminescence band at 2.4 eV in aluminum nitride bulk crystals, for which we find strong indications to be related to silicon DX centers. Time resolved photoluminescence spectroscopy using a sub-bandgap excitation reveals two different recombination processes with very long decay times of 13ms and 153 ms at low temperature. Based on the results of temperature and excitation dependent photoluminescence experiments, the process with the shorter lifetime is assigned to a donor-acceptor pair transition involving the shallow silicon donor state, which can be emptied with a thermal dissociation energy of 65meV. The slower process with a thermal quenching energy of 15 meV is assigned to the slightly deeper Si DX state known from electron paramagnetic resonance experiments, which is transferred back to the shallow donor state. [ABSTRACT FROM AUTHOR]

Electron paramagnetic resonance spectroscopy is used to investigate the thermal stability of the Aluminum-Zinc vacancy (AlZn-VZn) complex created in bulk single crystalline ZnO by room temperature electron irradiation with an energy of 1.2MeV. Two different stages in the annealing process at 160 and 250 ° C with apparent activation energies of EA1 ± 1.560.2 eV and EA2 = 1.9 ± 0.2 eV, respectively, are observed. The second stage leads to the complete annealing out of the (AlZn-VZn) complex and is accompanied by restoration of the concentration of the AlZn shallow donor centers to its initial value in as-grown (i.e., not irradiated) material. The obtained results prove that the (AlZn-VZn) complex is the dominant acceptor responsible for compensation of n-type-dopants in the studied Al-containing ZnO samples. [ABSTRACT FROM AUTHOR]