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Surface morphology, structural phases, and electron spin resonance (ESR) measurements were performed for Zn1‐xCuxO nanoparticles (x = 0.00, 0.01, 0.02, 0.03, 0.04, and 0.05) synthesized by sol‐gel method. The optimum annealing temperature (600°C) and weight loss was clarified using differential thermal analysis (DTA), and thermo gravimetric analysis (TG). By means of X‐ray diffraction (XRD) technique, the phase of the samples was defined as single with ZnO wurtzite hexagonal structure and proofed by Rietveld analysis for Zn0.98Cu0.02O sample with calculating c/a rate. Spherical shape random particle distributions were observed in all scanning electron microscope (SEM) measurements. ESR measurements were conducted for all samples and g‐value and ΔH (G) values were calculated and correlated from ESR measurements. [ABSTRACT FROM AUTHOR]

Herein, the magnetic behavior of BaxSr2–xTiCoO6 (BSTC) double perovskites synthesized by the conventional solid‐state reaction route is investigated. To understand the complexity of B‐site cations and their distribution in different valance states, X‐ray photoelectron spectroscopy (XPS) is performed. To understand the magnetic interactions at lower temperatures, variation of magnetization in both zero‐field‐cooled and field‐cooled conditions is studied in the temperature range from 2 to 300 K. Temperature dependence of inverse susceptibility is explained by modified Curie–Weiss law. Weak ferromagnetic and antiferromagnetic interactions are found in BSTC compounds, causing the randomness and frustrations and leading to a spin‐glass‐like behavior. To gain further insights, electron spin resonance (ESR) measurements are also carried out in BSTC ceramics. ESR measurement suggests the occurrence of Jahn–Teller glass analogous to the spin‐glass behavior in BSTC ceramics. [ABSTRACT FROM AUTHOR]

One of the bottlenecks often encountered in electro-Fenton technology is its low ability to produce hydrogen peroxide (H2O2). Thus, the hunt of suitable electrodes and reactor are a must to be tackled in order to improve the efficiency of the system. In this study, three-dimensional nickel foam was selected as cathode for in situ generating H2O2 efficiently and graphite was the control group in an enhanced oxygen mass transfer reactor. The micro-structure and electrochemical performance of electrodes were tested by scanning electron microscopy (SEM), X-ray diffraction (XRD), cyclic voltammetry (CV), electro-chemical impedance spectroscopy (EIS) and Tafel polarization techniques, respectively. The concentration of H2O2 produced by nickel foam cathode was 780.63 μmol/L and the removal efficiency of rhodamine B (RhB) was reached to 92.5% in 60 min. SEM and Tafel results showed that both nickel foam and graphite electrodes were porous structure cathodes. Moreover, CV and EIS experimental results indicated nickel foam electrode was controlled by charge transfer process while had a better transfer than graphite electrode. Electron spin resonance (ESR) spectra results demonstrated that the main oxidant species involved was ·OH, accounting for RhB degradation in electro-Fenton progress. Therefore, in terms of pollutant degradation in the electro-Fenton process, nickel foam electrode together with novel reactor was a promising technique. [ABSTRACT FROM AUTHOR]

The inner shelf sediments of the East China Sea (ECS) preserve valuable information regarding climatic changes on land through detrital material discharged from large rivers, particularly the Yangtze River. In this paper, we examine the provenance changes of fine-grained detrital quartz preserved in the sediment of the MD06-3040 core retrieved from the mud belt on the inner shelf of the ECS during the last 6 kyrs. The provenance of the fine silt fraction (4–16 μm) of the sediments, which is considered to represent the suspended particulate matter (SPM) from the Yangtze River, is estimated based on the electron spin resonance (ESR) signal intensity and crystallinity index (CI) of quartz. By comparing the ESR signal intensity and CI of quartz in the fine silt fraction of sediments to those from different parts of tributaries in the modern Yangtze River drainage, we can discriminate the SPM sourced from the northwestern and southeastern tributaries of the Yangtze River. Shifts in the East Asian summer monsoon (EASM) front are monitored by changes in the main precipitation areas which are manifested as changes in source rock ages and types implied from the ESR signal intensity and CI of quartz in the fine silt fraction of the studied sediments discharged from the Yangtze River. Temporal changes in provenance of the fine silt fraction through time suggest that shifts in the main location of EASM precipitation (most likely representing the EASM front) occurred at a multi-centennial-to-millennial scale with the deepest northwestward penetration of the EASM precipitation front (an enhanced EASM) occurring during the period 3.5–2.0 kyr BP and a southeastward retreat (a weak EASM) occurring during the periods 6.0–4.1 and 2.0–0 kyr BP. [ABSTRACT FROM AUTHOR]

BACKGROUND: Pork is used as raw material to produce Cantonese sausage, and 0.5 or 1 g kg−1 of d‐sodium erythorbate is added to the pork meat. In this study the myoglobin oxidation rate, relative metmyoglobin content, heme iron content, redness, pH, free radical content and thiobarbituric acid reactive substance (TBARS) value were measured at different processing times and different content of d‐sodium erythorbate. RESULTS: It was found that d‐sodium erythorbate significantly reduced the free radical content and myoglobin and lipid oxidation rates and increased heme iron levels. When d‐sodium erythorbate was added to the sausage, the absorption peak of myoglobin porphyrin shifted left, migrating from 414 to 405 nm. At 72 h, with an increase in the d‐sodium erythorbate content, a significant negative correlation was identified between heme iron and the degree of redness (P < 0.01). CONCLUSION: During sausage processing, there are strong correlations among TBARS values, free radical content, metmyoglobin levels, heme iron levels, a* and pH at the same d‐sodium erythorbate level. At the same processing time, adding d‐sodium erythorbate can slow the rate of myoglobin and lipid oxidation and prevent the discoloration of sausage. © 2019 Society of Chemical Industry [ABSTRACT FROM AUTHOR]

Biomass pyrolysis technology has important developmental prospects for biofuels and chemicals. Biochar as one of main pyrolysis products has excellent performance in soil improvement and adsorption of harmful elements. The environmentally persistent free radicals (EPFRs) in corn stalk powder and biochar obtained by pyrolysis at different temperatures were tested by electronic paramagnetic resonance spectrometry. After pyrolysis treatment, the biochar had a large number of stable free radicals. With increased pyrolysis temperature, the peak width of the free radicals signal in biochar decreased remarkably, and the widest peak of free radicals signal in biochar was presented at 450 °C, which was 0.69×10-4 T. The g-factor of free radicals in biochar decreased continuously as the temperature increased, while the peak height of free radicals first increased and then decreased. The peak height at 600 °C was only 23.8% of the peak height at 500 °C. The concentration of EPFRs in biochar increased with the increase of temperature from 450 °C to 500 °C, while it decreased at higher temperature (>500 °C). This phenomenon was similar to the trend of bio-oil collection efficiency. The experimental results showed a correlation between EPFRs of biochar and bio-oil yield at different pyrolysis temperatures. [ABSTRACT FROM AUTHOR]

This study aims to investigate the influences of a combination of cocatalysts including triethylaluminum (TEA) and tri-n-octylaluminum (TnOA) for activation of a commercial Ti-based Ziegler-Natta catalyst during ethylene polymerization and ethylene/1-hexene copolymerization on the change in Ti3+ during polymerization. Thus, electron spin resonance (ESR) technique was performed to monitor the change in Ti3+ depending on the catalyst activation by a single and combination of cocatalyst. It revealed that the amount of Ti3+ played a crucial role on both ethylene polymerization and ethylene/1-hexene copolymerization. For ethylene polymerization, the activation with TEA apparently resulted in the highest catalytic activity. The activation with TEA+TnOA combination exhibited a moderate activity, whereas TnOA activation gave the lowest activity. In case of ethylene/1-hexene copolymerization, it revealed that the presence of 1-hexene decreased activity. The effect of different cocatalysts tended to be similar to the one in the absence of 1-hexene. The decrease of temperature from 80 to 70 °C in ethylene/1-hexene copolymerization tended to lower catalytic activity for TnOA and TEA+TnOA, whereas only slight effect was observed for TEA system. The effect of different cocatalyst activation on the change of Ti3+ state of catalyst was elucidated by ESR measurement. It appeared that the activation of catalyst with TEA+TnOA combination essentially inhibited the reduction of Ti3+ to Ti2+ leading to lower activity. Furthermore, the polymer properties such as morphology and crystallinity can be altered by different cocatalysts. [ABSTRACT FROM AUTHOR]

FP-9120 positive photoresist films 1.8 μm thick implanted with boron and phosphorus ions deposited onto the surface of KDB-10 single-crystal (111) silicon wafers by centrifugation are investigated by their conductivity and electron spin resonance measurements. It is shown that the Р+ ion implantation leads to the formation of a layer with an electronic conductivity of about 10−9 Ω−1 cm−1. At a phosphorous implantation dose of 6 × 1015 cm−2, the electron spin resonance spectrum contains a narrow isotropic line with a g factor of 2.00654 and a width of 3.83 G, which is most likely related to the formation of phenoxy radicals. As the implantation dose increases to 1.2 × 1016 cm−2, a line with a g factor of 2.00264 and a width of 3.96 G is detected in the electron spin resonance spectrum, which is caused by unpaired electrons delocalized according to the π-polyconjugated system. [ABSTRACT FROM AUTHOR]

Mercury chalcogenide (Hg0.865Mn0.135Te) monocrystal was grown by crystallization from a two-phase mixture with replenishment of the melt from a tellurium solution and has n-type conductivity. The electron spin resonance (ESR) spectra of a single crystal were studied before and after X-irradiation. Only one intense anisotropic ESR line was observed at 4.2 K before X-irradiation. The anisotropy parameters were established from the angular dependence of the resonance field of the ESR line. After X-irradiation, three ESR lines were registered in the spectrum. The first and second lines with a large g-factor and unusual temperature dependencies were associated with charge carriers localized on defects with the strong exchange interaction with the manganese ion spins. The third ESR narrowed line was identified as signal from Mn2+ ions. Estimated anisotropic exchange parameters from angular dependencies of magnetic resonance field depend on temperature. The temperature dependencies of ESR linewidths are well described by the Korringa law and spin-lattice relaxation contributions. The discontinuities in temperature dependencies of resonance field and linewidth at 18 and 65 K were observed. [ABSTRACT FROM AUTHOR]

Electron spin resonance (ESR) experiments in YbRh2Si2 Kondo lattice (TK ≃ 25 K) at different field/frequencies (4.1 ≤ ν ≤ 34.4 GHz) and H⊥ c revealed: (i) a strong field dependent Yb3 + spin-lattice relaxation, (ii) a weak field and T-dependent effectiveg -value, (iii) a suppression of the ESR intensity beyond 15% of Lu-doping, and (iv) a strong sample and Lu-doping (≤ 15 %) dependence of the ESR data. These results suggest that the ESR signal in YbRh2Si2 may be due to a coupled Yb3 +-conduction electron resonant collective mode with a subtle field-dependent spins dynamic. © 2009 Elsevier B.V. All rights reserved.

• Rare-earth (RE = Y, La, Gd, Ho) substituted magnetite based ferrofluids have been prepared. • Crystallite sizes of the magnetic nanoparticles (MNPs) are of the order of 8 nm to 14 nm. • Magnetic measurement reveals superparamagnetic behaviour of the MNPs. • Spin resonance parameters and spin–spin relaxation time are calculated. • Rheological study of the ferrofluids under a shear flow and varying magnetic field has been carried out. In the present study, magnetite based ferrofluids having the composition Fe 3-x RE x O 4 (x = 0.0, 0.06) (RE = Y, La, Gd, Ho) have been prepared using chemical co-precipitation method to study the role of different rare-earth (RE) substitution on the various structural, microstructural, magnetic and rheological properties. X-ray diffraction (XRD) study confirm the spinel structure of the ferrite, which is further supported by fourier transform infrared spectroscopy (FTIR) study. The crystallite sizes of the samples are calculated from the XRD data using Scherrer formula, and found to be in the range 8 nm to 14 nm which is in agreement with the particle size obtained from transmission electron microscope (TEM) study. Dynamic light scattering (DLS) study shows the hydrodynamic particle size in the range 42 nm to 68 nm which is comparatively higher than those obtained from XRD, indicating the presence of aggregates in the ferrofluid samples. Vibrating sample magnetometer (VSM) measurement shows superparamagnetic behaviour for the investigated samples which is desirable for biomedical applications. Various parameters like resonant field (H rf), g-value, peak-to peak linewidth (ΔH pp) and spin–spin relaxation time (T 2) are calculated from the electron spin resonance spectroscopy (ESR) studies. It is observed that ΔH pp decreased with RE substitution indicating improvement in magnetic homogeneity, while the spin–spin relaxation time (T 2) is found to be of the order of picoseconds which points towards their suitability for magnetic resonance applications. Rheological measurements have been performed under a shear rate flow at varying magnetic field to investigate the flow properties of the ferrofluid samples. Shear thinning behaviour with large yield stress is observed in the non-Newtonian fluids. [ABSTRACT FROM AUTHOR]

Nanocrystalline Ni 0.5 Co 0.5 RE 0.03 Fe 1.97 O 4 (RE = Ce, Nd, Gd) were synthesized by glycol-thermal method. Fourier transform infrared spectroscopy (FTIR) and X-ray diffraction (XRD) results confirm the formation of single-phase spinel ferrite. The crystallite sizes ranged from 6.29 nm to 9.41 nm which was comparable to results obtained using Williamson-Hall (W–H) method. Lattice parameters were found to vary from 8.356 Å to 8.370 Å depending on an ionic radii of a substituted rare-earth elements. Large specific surface areas ranging between 120 m2/g and 160 m2/g were associated with smaller crystallite sizes. Scanning electron microscope (SEM) revealed homogeneous and clustered nanoparticles. The energy dispersive X-ray (EDS) spectra revealed the existence of nickel (Ni), cobalt (Co), iron (Fe), and oxygen (O) in an undoped sample. The additional characteristic peaks of cerium (Ce), neodymium (Nd) and gadolinium (Gd) were observed for doped samples. The electron spin resonance (ESR) results demonstrated g -values ranging between 3.10 and 3.79 which indicated strong exchange interaction between nanoparticles, type of morphology, and crystalline nature of particles. These high g -values make Ni 0.5 Co 0.5 RE 0.03 Fe 1.97 O 4 (RE = Ce, Nd, Gd) materials suitable for applications in high-frequency devices. The Mössbauer spectroscopy results revealed the formation of broadened Zeeman lines and quadrupole-split lines as well as the presence of the Fe3+ ions at B sites in the samples. [Display omitted] • Ni 0.5 Co 0.5 RE 0.03 Fe 0.197 O 4 (RE = Ce, Nd, Gd) nanoferrites were synthesized by glycol-thermal process. • XRD and FTIR confirmed the single-phase formation and cubic spinel structure. • Large ESR parameters make these materials suitable for applications in high-frequency devices. • Mössbauer results revealed presence of paramagnetic state. [ABSTRACT FROM AUTHOR]

Oleogels are made by structuring oils with an oleogelator, e.g., ethyl cellulose (EC), and can be used as fat replacers in foods. Also, oleogels made from oils rich in bioactives, e.g., tucumã oil (TCO), could possess additional nutritional benefits. However, sensitive compounds are often degraded during the harsh conditions of most oleogelation procedures. Here we present an adapted low-temperature indirect method (IM) to structure TCO with EC, which is based on emulsification with aqueous ethanol as continuous phase, and the physicochemical properties are compared to oleogels with the same composition but produced by a direct method (DM) at high temperature. For IM, TCO was emulsified with EC ethanolic dispersions, followed by solvent removal and shearing. DM resulted in weak gels (G' < 10000 Pa), with low oil binding capacity (OBC) (12.63–66.26%), low carotenoid retention (CR) (20.7–31.6%) and complete depletion of α-tocopherol. Conversely, IM provided strong oleogels (G' > 10000 Pa), with high OBC (87.82–100.04%), CR (>95%) and α-tocopherol content (293–322 mg/kg). TCO oleogels with different physical properties and retention of sensitive compounds were obtained by DM and IM, showing the potential of IM oleogelation to preserve bioactives in the oleogels and producing healthier fat alternatives for the food industry. • First report of tucumã oil oleogels produced by direct and indirect methods. • Effective use of ethyl cellulose as oleogelator in emulsion-templated oleogelation. • Strong oleogels with high retention of bioactives were obtained by indirect gelation. • Weak oleogels prepared directly showed great loss of carotenoids and α-tocopherol. [ABSTRACT FROM AUTHOR]

• Ultrasonic irradiation of carbonated water generated long-lived nanobubbles (NBs). • NB suspension and its atomized mist showed strong, durable bactericidal activity. • The bactericidal activity was attributed to NBs filled with high-pressure CO 2 gas. • A mechanism was proposed for reactive oxygen species generation from the NBs. Our previous study showed that nanobubbles (NBs) encapsulating CO 2 gas have bactericidal activity due to reactive oxygen species (ROS) (Yamaguchi et al., 2020). Here, we report that bulk NBs encapsulating CO 2 can be efficiently generated by ultrasonically irradiating carbonated water using a piezoelectric transducer with a frequency of 1.7 MHz. The generated NBs were less than 100 nm in size and had a lifetime of 500 h. Furthermore, generation of ROS in the NB suspension was investigated using electron spin resonance spectroscopy and fluorescence spectrometry. The main ROS was found to be the hydroxyl radical, which is consistent with our previous observations. The bactericidal activity lasted for at least one week. Furthermore, a mist generated by atomizing the NB suspension with ultrasonic waves was confirmed to have the same bactericidal activity as the suspension itself. We believe that the strong, persistent bactericidal activity and radical generation phenomenon are unique to NBs produced by ultrasonic irradiation of carbonated water. We propose that entrapped CO 2 molecules strongly interact with water at the NB interface to weaken the interface, and high-pressure CO 2 gas erupts from this weakened interface to generate ROS with bactericidal activity. [ABSTRACT FROM AUTHOR]

Radicals produced in alanine by irradiation of 2–7 keV X-rays were investigated by ESR applications; i.e., CW-ESR, pulse-ESR and ESR imaging. The relative radical yield decreased with the decreasing photon energy and the increasing dose. The 2D imaging showed that the radical concentration at the surface was extremely low even though the absorption of X-rays exponentially decreased with the penetration depth. The depth of the radical concentration peak was almost the same as the penetration depth for the X-ray irradiation with an energy lower than 5-keV. The product formed by radical recombination was observed by an LC/MS (liquid chromatograph-mass spectrum) analysis. For the soft X-ray irradiation, many radicals will be lost by the efficient radical-radical recombination due to the higher density of the radicals, similar to the high-LET irradiation by heavy ions. The spin-spin relaxation rate (1/T 2), which correlates with the radical concentration, increased by the decreasing photon energy. The values of 1/T 2 for the soft X-rays were compatible to that for the heavy ions with the high-LET. Based on these observations, it is concluded that the effects of irradiation by soft X-rays are similar to high-LET irradiation. • The relative radical yield from soft X-rays decreased with decreasing photon energy. • The radical concentration at the surface was much lower than the energy dispersion. • The spin-spin relaxation rate increased with decreasing photon energy. • The product formed from the radical recombination was observed by LC/MS analysis. • The effects of irradiation by soft X-rays are similar to high-LET irradiation. [ABSTRACT FROM AUTHOR]

Aureobasidium pullulans β-(1 → 3, 1 → 6)-glucan (APG) has a high degree of β-(1 → 6)-glucosyl branching and a regular triple helical structure similar to that of schizophyllan. In this study, APG was carboxymethylated to different degrees of substitution (DS = 0.51, 1.0, and 2.0, denoted CMAPG 1–3, respectively) using a heterogeneous reaction. With increasing DS, the triple-helix structure drastically decreased and converted to a random coil structure in CMAPG 3. Further, aqueous solutions of CMAPG changed from pseudoplastic fluids to perfect Newtonian liquids with increasing DS, indicating that the intra- and intermolecular hydrogen bonds had been cleaved by the substituents to form a random coil structure. In addition, APG and CMAPG solutions exhibited scavenging ability against hydroxyl, organic, and sulfate radicals. It was also found that the carboxymethylation of APG drastically enhanced the organic radical scavenging ability. On the basis of the relationship between the DS and radical scavenging ability of the CMAPG samples, we believe hydroxyl and organic radicals were preferably scavenged by the donation of hydrogen atoms from the glucose rings and the methylene moieties of the carboxymethyl groups, respectively. Considering the obtained results, CMAPG and APG are expected to have applications in pharmaceuticals, functional foods, and cosmetics as antioxidant polysaccharides. [Display omitted] [ABSTRACT FROM AUTHOR]

The ability of sodium caprylate and l-menthol to fluidize phospholipid bilayers composed of lipids simulating the buccal epithelium was investigated using electron spin resonance (ESR) to evaluate the action of these agents as permeation enhancers. 5-Doxyl stearic acid (5-DSA) and 16-doxyl stearic acid (16-DSA) were used as spin labels to identify alterations in membrane fluidity near the polar head groups or inner acyl regions of the lipid bilayer, respectively. The molecular motion of both 5-DSA and 16-DSA showed increased disorder near the polar and inner hydrophobic regions of the bilayer in the presence of sodium caprylate suggesting fluidization in both the regions, which contributes to its permeation enhancing effects. L-menthol decreased the order parameter for 16-DSA, showing membrane fluidization only in the inner acyl regions of the bilayer, which also corresponded to its weaker permeation enhancing effects. The rapid evaluation of changes in fluidity of the bilayer in the presence of potential permeation enhancers using ESR enables improved selection of effective permeation enhancers and enhancer combinations based on their effect on membrane fluidization.

The angiogenin protein (ANG) is one of the most potent endogenous angiogenic factors. In this work we characterized by means of potentiometric, spectroscopic and voltammetric techniques, the copper complex species formed with peptide fragments derived from the N-terminal domain of the protein, encompassing the sequence 1-17 and having free amino, Ang1-17, or acetylated N-terminus group, AcAng1-17, so to explore the role of amino group in metal binding and cellular copper uptake. The obtained data show that amino group is the main copper anchoring site for Ang1-17. The affinity constant values, metal coordination geometry and complexes redox-potentials strongly depend, for both peptides, on the number of copper equivalents added. Confocal laser scanning microscope analysis on neuroblastoma cells showed that in the presence of one equivalent of copper ion, the free amino Ang1-17 increases cellular copper uptake while the acetylated AcAng1-17 strongly decreases the intracellular metal level. The activity of peptides was also compared to that of the protein normally present in the plasma (wtANG) as well as to the recombinant form (rANG) most commonly used in literature experiments. The two protein isoforms bind copper ions but with a different coordination environment. Confocal laser scanning microscope data showed that the wtANG induces a strong increase in intracellular copper compared to control while the rANG decreases the copper signal inside cells. These data demonstrate the relevance of copper complexes’ geometry to modulate peptides’ activity and show that wtANG, normally present in the plasma, can affect cellular copper uptake.