Resonance Spectra Research Articles

Role of gemini surfactants with biodegradable spacer as efficient capping agents of silver nanoparticles

Since the last decade, silver nanoparticles (AgNPs) continue to attract interest of both academia and industry due to their peculiar physical, chemical, and optical properties. In the field of pharmaceutical applications, they are efficient carriers in the processes of controlled drug release, improve the drug's bioavailability, act as efficient antimicrobial agents and provide other biological functions conveyed at the nanometric scale. The known issue hampering further development of applications of AgNPs is their instability in aqueous environment. The present study utilizes two series of cationic bisammonium gemini surfactants with two dodecyl chains and a biodegradable spacer containing two amide or ester groups for the stabilization of AgNPs. The presence of nanosilver in the dispersions was confirmed by UV–VIS plasmon resonance spectra. Stability of AgNPs was characterized by zeta potential measurements proving that amide and ester gemini surfactant series are able to effectively stabilize AgNPs. The particles size analysis utilizing dynamic light scattering and scanning electron microscopy showed that AgNPs stabilized with flexible ester-based gemini surfactants have their size smaller than those capped with amide-containing gemini surfactants. Antimicrobial and anti-inflammatory activity determination as well as cytotoxicity experiments with gemini surfactant stabilized AgNPs showed a complex dependence of biological activity of AgNPs on the molecular structure of stabilizing agents.

Constructing Cu-Mn bimetallic synergistic sites in 2D metal-organic framework nanosheets to induce polarized charge distribution: Electronic structure transformation and evaluation of Fenton-like performance

Heterogeneous Fenton-like process based on H2O2 was an efficient method for the abatement of micropollutants in water. However, the mass transport resistance caused by the limited access between catalytic sites and target chemicals still restrict the decontamination efficiencies. Metal-organic frameworks (MOFs) with uniformed pores and anbundant metal sites shows great potentail in environmental remediation, Here, a novel two-dimensional nanosheet consisting of Cu and Mn bimetallic-oxygen clusters (CuMn-BDC, BDC refers to terephthalic acid organic ligand) was rationally designed and characterized. The introduction of second metal Mn changed the surface electronic distribution and accelerated the electron transfer of pristine Cu-based nanosheet, leading to improved catalytical acticities and removal effeciencies (kSA) for Sulfamethoxazole (SMX). The catalytic activity of CuMn-BDC obtained (5.76 × 10–4) was 3.95 times higher than that of Cu-BDC (1.46 × 10–4), demonstrating that the CuMn-BDC showed higher reaction rates than that of Cu-BDC when same amount of H2O2 was added. The interfacial micro-electric fields in bimetallic MOFs increased the interaction of organic pollutants and transfer the electron to activate H2O2. Several quenching experiments, electron paramagnetic resonance spectra and theoretical calculations were performed to study the reaction mechanism systematically. Further the powder was fabricated into membrane with higher water stablities. This study shed light on develop efficient 2D-MOFs catalyst for the abatement of micropollutants in water.

Breaking New Ground towards Innovative Synthesis of Palladacycles: The Electrochemical Synthesis of a Tetranuclear Thiosemicarbazone-[C,N,S] Palladium(II) Complex.

The electrochemical oxidation of anodic metals (M = nickel and palladium) in an acetonitrile solution of the thiosemicarbazone ligands (E)-2-(1-(4-methoxyphenyl)ethylidene)-N-methylhydrazine-1-carbothioamide (a), (E)-2-(1-(p-tolyl)ethylidene)hydrazine-1-carbothioamide (b), and (E)-N-phenyl-2-(1-(p-tolyl)ethylidene)hydrazine-1-carbothioamide (c) yielded the homoleptic complexes [ML2], 1a, 1b, 1c, and 2c and [M4L4], 2a as air-stable solids. The crystal structures for 1a, 1b, 1c, and 2c show the ligands in a transoid disposition with the [S,S] and [N,N] donor atom pairs occupying cis positions on the nearly square planar coordination plane of the metal. The structure for 2a of S4 symmetry comprises a tetranuclear palladacycle where the metalated ligands are arranged around a central Pd4S4 environment: a crown ring with alternating palladium and sulfur atoms. The latter complex is the first example of an electrochemical preparation of a cyclometalated palladium compound, marking a milestone in the chemistry of such species. The compounds have been fully characterized by elemental microanalysis, mass spectrometry, infrared (IR), and 1H nuclear magnetic resonance (NMR) spectra.

Changes in Electron Paramagnetic Resonance Parameters Caused by Addition of Amphotericin B to Cladosporium cladosporioides Melanin and DOPA-Melanin-Free Radical Studies.

Cladosporium cladosporioides are the pigmented soil fungi containing melanin. The aim of this work was to determine the influence of amphotericin B on free radicals in the natural melanin isolated from pigmented fungi Cladosporium cladosporioides and to compare it with the effect in synthetic DOPA-melanin. Electron paramagnetic resonance (EPR) spectra were measured at X-band (9.3 GHz) with microwave power in the range of 2.2-70 mW. Amplitudes, integral intensities, linewidths of the EPR spectra, and g factors, were analyzed. The concentrations of free radicals in the tested melanin samples were determined. Microwave saturation of EPR lines indicates the presence of pheomelanin in addition to eumelanin in Cladosporium cladosporioides. o-Semiquinone free radicals in concentrations ~1020 [spin/g] exist in the tested melanin samples and in their complexes with amphotericin B. Changes in concentrations of free radicals in the examined synthetic and natural melanin point out their participation in the formation of amphotericin B binding to melanin. A different influence of amphotericin B on free radical concentration in Cladosporium cladosporioides melanin and in DOPA-melanin may be caused by the occurrence of pheomelanin in addition to eumelanin in Cladosporium cladosporioides. The advanced spectral analysis in the wide range of microwave powers made it possible to compare changes in the free radical systems of different melanin polymers. This study is important for knowledge about the role of free radicals in the interactions of melanin with drugs.

γ-radiation-induced centers in irradiated perovskite SrCeO3 and their role in thermally stimulated reactions: Fluorescence, thermally stimulated luminescence, electron paramagnetic resonance and shielding studies

One promising host for actinide radioactive wastes is orthorhombic perovskite-type oxide. Perovskite SrCeO3 ceramic was synthesized by nitrate-fuel combustion, which includes the organic fuel glycine. Powder X-ray diffraction was utilized to determine the structural features, and γ-radiation-induced changes and shielding properties were investigated in perovskite SrCeO3. In a mixed-phase sample, a bright sky-blue luminescence was observed, and two thermoluminescence (TL) peaks were seen in irradiated SrCeO3 ceramic. Electron paramagnetic resonance (EPR) spectrum in γ-irradiated SrCeO3 ceramic had contributions from five defect centers. Center I having an isotropic g-value equal to 2.0283, is ascribed to an O− ion, while center II with an axial g-tensor with principal values g|| = 2.0224 and g⊥ = 2.0068 is determined as an O2− ion. O− ion relates to the TL peak at 215 °C. Center III with a g-value equal to 2.0009 is identified as an F+ center and is related to the 185 °C TL peak. The defect center associated with center IV is also identified as an F+ center. An additional defect center in the higher field region of the spectrum is assigned to an F+ center, and the center results from an F-center (oxygen vacancy with two electrons). The mass attenuation coefficients, effective atomic numbers, and half-value layer thicknesses concerning shielding property effectiveness were computed and it was found that the perovskite SrCeO3 ceramic provided superior γ-shielding properties.

Structural characterization and antioxidant activity mechanism of the ferulic acid-rich subfraction from sugar beet pectin

The feruloylated sugar chain in sugar beet pectin (SBP) is a natural polyphenol-polysaccharide complex. Its low abundance often leads to be neglected, thereby hindering its bioactivity and mechnism research. In this study, SBP-3 A, a novel feruloylated polysaccharide fragment, was isolated from sugar beet pectin utilizing enzymatic digestion. The presence of ferulic acid on SBP-3 A was confirmed through high-performance liquid chromatography (HPLC), with a mass fraction of 22.5 μg/mg. The average molecular weight was determined to be 33.31 kDa. Methylation analysis, and nuclear magnetic resonance (NMR) spectra revealed that SBP-3 A is a heteroglycan with the main chain structure of →2)-α-Rhap-(1 → 4)-α-GalpA-(1 → 2)-α-Rhap-(1→, and the branched chain structure of ferulic acid (FA) → 3,4)-β-Galp-(1 → 2,4)-α-Rhap-(1→. Subsequently, the antioxidant activity of SBP-3 A was evaluated using the Caenorhabditis elegans (C. elegans). SBP-3 A improved antioxidant enzymes and non-enzymatic defense system, decreased reactive oxygen species levels, and up-regulated the mRNA expression of sod-3, skn-1, and daf-16, while down-regulated the expression of age-1 in C. elegans. Moreover, SBP-3 A modulated the gut flora by favorably affecting the abundances of Lactobacillus, Ligilactobacillus, and Akkermansia, thereby enhancing antioxidant capacity in C. elegans. Consequently, the aforementioned findings support the potential application of SBP-3 A as a functional food for treating oxidative stress-related illnesses.

Arabidopsis Dph4 is an Hsp70 Cochaperone with Iron-Binding Properties.

J-domain proteins (JDPs) are obligate cochaperones of Hsp70s with a wide range of functions in protein homeostasis. Although the J-domain is required for the stimulation of Hsp70s ATPase activity, the functional specificity of JDPs is governed by domains or regions other than the J-domain. Jjj3/Dph4, a class III JDP, is required for diphthamide (DPH) biosynthesis in eukaryotes, including yeast and mammals. Dph4 has a conserved N-terminal J-domain and an uncharacterized C-terminal domain containing a signature CSL zinc finger motif. Previously, we showed that the Dph4 ortholog in Arabidopsis thaliana (atDjC13/AtJjj3/AtDph4) could restore DPH biosynthesis in yeast jjj3Δ mutant in a J-domain-dependent manner. Here, we characterize the C-terminal CSL motif of AtDph4 using yeast genetic and biochemical approaches. The CSL motif of AtDph4 is essential for DPH biosynthesis, and like human Dph4, AtDph4 showed distinct iron-binding activity, which is not present in its yeast counterpart. ScDph4 and AtDph4 proteins exhibit distinct iron-binding capabilities, as evidenced by UV-vis spectrophotometry, SEM-EDS (energy-dispersive spectroscopy function on the scanning electron microscope) and electron paramagnetic resonance (EPR) spectra analyses. Collectively, our data suggests that beyond their role as an Hsp70 cochaperone, Dph4 homologues in complex eukaryotes may have iron-binding abilities, indicating a potential role in iron-sulfur cluster assembly and iron homeostasis.

Synthesis and annealing effect of structural, morphology, optical, and magnetic properties of tin telluride (SnTe)

This study explored the structural, vibrational, morphological, optical, and magnetic characteristics of both as-grown and annealed single crystals of tin telluride (SnTe), employing diverse analytical techniques. X-ray powder diffraction (XRD) analysis shows the cubic lattice structure of SnTe with consistent lattice parameters across different temperatures, along with the phase transition phenomenon. Fourier Transform Infrared Spectroscopy (FTIR) elucidates temperature-induced shifts in vibrational modes, indicating sensitivity to thermal stimuli. Scanning electron microscopy (SEM) reveals layer-by-layer growth patterns and temperature-dependent variations in crystal morphology. Energy-dispersive X-ray analysis (EDAX) confirms the synthesized crystals' high purity and slight tellurium-rich composition. Optical band gap measurements demonstrate an increase in band gap upon annealing, attributed to valence band convergence. Field-dependent magnetization (M − H) curves exhibit ferromagnetic properties at ambient temperature, which escalate with increasing annealing temperature. Electron Paramagnetic Resonance (EPR) spectra reveal spin mobility and exchange coupling, with variations in the g-factor suggesting the presence of additional spin entropy. These observations offer significant insights into the complex properties of SnTe, which are crucial for its potential applications across various technological fields.

Insights into the efficient removal and mechanism of NiFeAl-LDH with abundant hydroxyl to activate peroxymonosulfate for sulfamethoxazole wastewater

Layered double hydroxide (LDH) material with abundant OH was successfully prepared by co-precipitation method, and a water purification system of Ni2Fe0.25Al0.75-LDH activated peroxymonosulfate (PMS) was constructed to rapidly degrade sulfamethoxazole (SMX) pollutants. The optimal conditions for the degradation of SMX in the system were as follows: 0.30 g/L Ni2Fe0.25Al0.75-LDH, 0.30 mM PMS, pH = 7 and 90 % SMX was removed in 10 min and almost completely in 40 min, which was consistent with the predicted results of response surface methodology (RSM) analysis. The abundant OH in Ni2Fe0.25Al0.75-LDH could form M(O)OSO3 complexes with PMS, accelerating the generation of reactive oxygen species (ROS) and promoting the removal of SMX. Quenching experiments and electron paramagnetic resonance (EPR) spectra showed that SO4−, OH, O2− and 1O2 also existed in the system. The surface-bound SO4− and O2− contributed greatly to the removal of SMX and the electron transfer between metals was also conducive to the production of active substances. The possible degradation pathways and intermediates of SMX were proposed. The toxicity assessment software tool (T.E.S.T) and total organic carbon (TOC) results indicated that the Ni2Fe0.25Al0.75-LDH/PMS system could reduce the overall environmental risk of SMX to some extent. This study provided a new strategy for the practical application of heterogeneous catalysts in sewage treatment.

Vector magnetometry in zero bias magnetic field using nitrogen-vacancy ensembles

Abstract The application of the vector magnetometry based on Nitrogen-Vacancy (NV) ensembles has been widely investigated in multiple areas. It has the superiority of high sensitivity and high stability in ambient conditions with microscale spatial resolution. However, a bias magnetic field is necessary to fully separate the resonance lines of optically detected magnetic resonance (ODMR) spectrum of NV ensembles. This brings disturbances in samples being detected and limits the range of application. Here, we demonstrate a method of vector magnetometry in zero bias magnetic field using NV ensembles. By utilizing the anisotropy property of fluorescence excited from NV centers, we analyzed the ODMR spectrum of NV ensembles under various polarized angles of excitation laser in zero bias magnetic field with a quantitative numerical model and reconstructed the magnetic field vector. The minimum magnetic field modulus that can be resolved accurately is down to ~0.64 G theoretically depending on the ODMR spectral line width (1.8MHz), and ~2 G experimentally due to noises in fluorescence signals and errors in calibration. By using 13C purified and low Nitrogen concentration diamond combined with improving calibration of unknown parameters, the ODMR spectral line width can be further decreased below 0.5 MHz corresponding to ~0.18 G minimum resolvable magnetic field modulus.

Cryogenic Thermo-Optical Coefficient of SU-8 Measured Using a Racetrack Resonator at 850 nm

SU-8 is an emerging polymer material for integrated optical circuits that has demonstrated good structural properties in a cryogenic environment. In this article, we investigate the thermo-optical properties of SU-8 for a wavelength λ = 850 nm, from room temperature to cryogenic temperature down to 14 K. To measure the material properties, we designed and fabricated SU-8 racetrack resonators via electron beam lithography. While cooling the device in a closed-cycle cryostat, we measured the resonance spectrum as a function of the temperature from which we determined the temperature-induced variations of the group and effective indices of the waveguide. With the aid of waveguide eigenmode simulations, we used these data to derive the temperature dependence of the SU-8 refractive index nSU−8 (T). At room temperature (T~295 K), the thermo-optic coefficient dnSU−8/dT = −5.3 ± 0.2 × 10−5 K−1. At low temperature (T~14 K), dnSU−8/dT = −1.27 ± 0.05 × 10−4 K−1. Our research shows the potential of SU-8 photonics in a cryogenic environment, suitable for the integration with quantum light sources emitting in the near infrared (NIR).

Nuclear-Magnetic-Resonance-Spectroscopy-Derived Serum Biomarkers of Metabolic Vulnerability Are Associated with Disability and Neurodegeneration in Multiple Sclerosis.

Metabolic vulnerabilities can exacerbate inflammatory injury and inhibit repair in multiple sclerosis (MS). The purpose was to evaluate whether blood biomarkers of inflammatory and metabolic vulnerability are associated with MS disability and neurodegeneration. Proton nuclear magnetic resonance spectra were obtained from serum samples from 153 healthy controls, 187 relapsing-remitting, and 91 progressive MS patients. The spectra were analyzed to obtain concentrations of lipoprotein sub-classes, glycated acute-phase proteins, and small-molecule metabolites, including leucine, valine, isoleucine, alanine, and citrate. Composite indices for inflammatory vulnerability, metabolic malnutrition, and metabolic vulnerability were computed. MS disability was measured on the Expanded Disability Status Scale. MRI measures of lesions and whole-brain and tissue-specific volumes were acquired. Valine, leucine, isoleucine, alanine, the Inflammatory Vulnerability Index, the Metabolic Malnutrition Index, and the Metabolic Vulnerability Index differed between healthy control and MS groups in regression analyses adjusted for age, sex, and body mass index. The Expanded Disability Status Scale was associated with small HDL particle levels, inflammatory vulnerability, and metabolic vulnerability. Timed ambulation was associated with inflammatory vulnerability and metabolic vulnerability. Greater metabolic vulnerability and inflammatory vulnerability were associated with lower gray matter, deep gray matter volumes, and greater lateral ventricle volume. Serum-biomarker-derived indices of inflammatory and metabolic vulnerability are associated with disability and neurodegeneration in MS.

Classification of Brain Magnetic Resonance Imaging Abnormalities and Spectrum of Neurological Findings in a Cohort with Copy Number Variation-Related Disorders

Introduction: Copy number variation (CNV) is the difference in the sequence of genomic segments, which can vary from one kilobase to several megabases. Certain CNVs have been linked to various human disorders, such as intellectual disability, multiple congenital anomalies, autism spectrum disorders, neurodegenerative and neuropsychiatric conditions, and cancer. The present study aims to classify brain magnetic resonance imaging (MRI) findings, describe neurological manifestations, and discuss the findings within the context of genotype–phenotype correlations in a cohort of patients with recurrent and nonrecurrent CNVs. Methods: A total of 21 patients with pathogenic CNV detected using microarray analysis were included in the study. Results: Analysis of the clinical findings of the patient cohort showed that 16 (76%) had microcephaly, 14 had epilepsy (66%), 20 had facial dysmorphism (95%), and all had developmental delay (100%). Novel brain MRI findings were detected in six (6/13, 46%) patients with recurrent CNV and five (5/8, 63%) patients with nonrecurrent CNV. Conclusion: CNV-related disorders should be considered in the differential diagnosis of patients with brain MRI findings suspicious for metabolic disorders. Brain MRI differences in patients with the same chromosomal deletion can be explained by the second-hit hypothesis. Additional single nucleotide variations and epigenetic factors in these cases may have led to the involvement of different regions of the brain. Revealing the phenotypic and genotypic characteristics of cases in rare disorders will contribute to the widespread use of precision medicine and genetic treatment approaches in the near future.

A General Formulation of the Resonance Spectrum Expansion Self-Shielding Method

The resonance spectrum expansion (RSE) self-shielding method was recently proposed by Nagoya and Osaka universities as a powerful alternative to existing approaches. First investigations of the RSE at Polytechnique Montreal show that it can effectively replace the actual subgroup method used for production calculations in DRAGON5. The Japanese implementation of the RSE method is limited to a solution of the Boltzmann transport equation (BTE) with the method of characteristics. We are proposing a new implementation of the RSE method compatible with various types of solutions for the BTE, including the collision probability and the interface current methods. We based our validation study on a subset made up of eight Rowlands pin cell benchmark cases. The absorption rates obtained after self-shielding are compared with exact values obtained using an elastic slowing-down calculation where each resonance is modeled individually in the resolved energy domain. Validation of Rowlands benchmark with effective multiplication factor calculations was also conducted with respect of the SERPENT2 Monte Carlo code. It is shown that the RSE method is compatible with both advanced and legacy energy meshes and performs slightly better than the production subgroup methods actually used.

Determining strain components in a diamond waveguide from zero-field optically detected magnetic resonance spectra of negatively charged nitrogen-vacancy-center ensembles

Determining strain components in a diamond waveguide from zero-field optically detected magnetic resonance spectra of negatively charged nitrogen-vacancy-center ensembles

ATP, the 31P Spectral Modulus, and Metabolism.

Adenosine triphosphate (ATP) has a high intracellular millimolar concentration (ca. 2.4 mM) throughout the phylogenetic spectrum of eukaryotes, archaea, and prokaryotes. In addition, the function of ATP as a hydrotrope in the prevention of protein aggregation and maintenance of protein solubilization is essential to cellular, tissue, and organ homeostasis. The 31P spectral modulus (PSM) is a measure of the health status of cell, tissue, and organ systems, as well as of ATP, and it is based on in vivo 31P nuclear magnetic resonance (31P NMR) spectra. The PSM is calculated by dividing the area of the 31P NMR integral curve representing the high-energy phosphates by that of the low-energy phosphates. Unlike the difficulties encountered in measuring organophosphates such as ATP or any other phosphorylated metabolites in a conventional 31P NMR spectrum or in processed tissue samples, in vivo PSM measurements are possible with NMR surface-coil technology. The PSM does not rely on the resolution of individual metabolite signals but uses the total area derived from each of the NMR integral curves of the above-described spectral regions. Calculation is based on a simple ratio of the high- and low-energy phosphate bands, which are conveniently arranged in the high- and low-field portions of the 31P NMR spectrum. In practice, there is essentially no signal overlap between these two regions, with the dividing point being ca. -3 δ. ATP is the principal contributor to the maintenance of an elevated PSM that is typically observed in healthy systems. The purpose of this study is to demonstrate that (1) in general, the higher the metabolic activity, the higher the 31P spectral modulus, and (2) the modulus calculation does not require highly resolved 31P spectral signals and thus can even be used with reduced signal-to-noise spectra such as those detected as a result of in vivo analyses or those that may be obtained during a clinical MRI examination. With increasing metabolic stress or maturation of metabolic disease in cells, tissues, or organ systems, the PSM index declines; alternatively, with decreasing stress or resolution of disease states, the PSM increases. The PSM can serve to monitor normal homeostasis as a diagnostic tool and may be used to monitor disease processes with and without interventional treatment.

Inverse-designed compact silicon waveguide reflector for on-chip resonators

Waveguide reflectors are crucial components in integrated optics and on-chip resonators, with their efficiency and dimensions significantly impacting system performance and integration. This paper presents an compact silicon on-chip waveguide reflector, designed using photonics inverse design, featuring a footprint of only 1.64μm×1.78μm and a simple, smooth structure. The simulation shows a 1 dB bandwidth over 400 nm and a reflectivity above 97.6% in the 1520–1570 nm wavelength range. Experimental measurements, conducted through Fabry-Pérot resonator spectrum analysis, confirm the excellent performance of the waveguide reflector, attaining a reflectivity over 92.8%. Additionally, the study presents two more waveguide reflectors tailored for the 1.31μm and 2μm wavelength, emphasizing the scalability of the design. The compact size and broadband reflectivity characteristics of the waveguide reflector provide increased flexibility in designing cavity lengths and directional couplers, making it a promising choice for applications in resonators and highly integrated photonics systems.

Effect of substitution of aluminium and neodymium on structural and magnetic properties of yttrium iron garnet studied using 57Fe internal field NMR

The structural and magnetic properties of non-magnetic aluminium and magnetic neodymium substituted yttrium iron garnet samples (Y3-xAlxFe5O12 and Y3-nNdnFe5O12) were investigated. Powder samples were synthesized using auto combustion route. The Rietveld refinement analysis of the samples confirmed the presence of the garnet phase and showed presence of minimal impurity phases, specifically perovskite and hematite. Substitution on Y3Fe5O12 with Al resulted in a linear decrease in saturation magnetization, while Nd substitution showed a non-linear change. In accordance with this the Internal Field Nuclear Magnetic Resonance (IFNMR) spectrum exhibited a downward shift in peak frequency when Al was substituted, and a significant reduction in intensity with Nd substitution in yttrium iron garnet samples. Aluminium ions take up either tetrahedral or octahedral positions in the lattice, apart from the dodecahedral site, because of their smaller ionic radii. This causes a decrease in the hyperfine field that originates from Fe3+ ions in tetrahedral and octahedral sites. On the other hand, neodymium ions occupy dodecahedral sites and are expected not to affect Fe ions. Concurrently, an observable peak shift was not observed in the IFNMR spectrum for Nd substitution. However, Nd substitution introduced strain in the lattice due to their larger ionic radii compared to yttrium, which they replace. This strain causes disorder in tetrahedral and octahedral sites and affects 57Fe signal intensity. The magnetic properties observed from VSM analysis is also interpreted in view of observed changes in the 57Fe IFNMR spectrum. X-ray Photoelectron spectroscopy (XPS) was employed mainly to explore spin orbit splitting of Fe 2p state in the samples.

Donor Defect Induced Ferromagnetism in Nb‐Doped ZnO Thin Films Grown by RF Magnetron Sputtering

The effect of Nb doping concentration (0, 1, 2, and 4 at. %) on donor defect‐induced ferromagnetism in ZnO thin films is investigated. The films are deposited on Si(111) substrates utilizing the radio frequency magnetron sputtering. X‐ray diffraction pattern unveils that the films show a pronounced orientation along the (002) direction. The relative intensities of defect‐related bands with that of the ultraviolet band from photoluminescence (PL) spectra show that 2 at. % Nb doping results in a greater number of donor defects (Zni+ and VO+) in the ZnO lattice. The parameters extracted from the electron paramagnetic resonance spectra follow a similar trend. The results from vibrating sample magnetometer measurement indicate that pure ZnO displays diamagnetic nature, whereas Nb‐doped ZnO exhibits a ferromagnetic nature. The saturation magnetization value is found highest for 2 at. % Nb doping, which correlates with the presence of a greater number of donor defects, as supported by the PL and electron paramagnetic resonance results. Images obtained from atomic force microscopy show that the surface roughness of the ZnO thin film reduces upon Nb doping. X‐ray photoelectron spectroscopy validates that Nb is doped in 2 at. % Nb‐doped ZnO thin film with Nb oxidation state of +5.

Solid-State Lithium Batteries with in-Situ Polymerized Acrylate-Based Electrolytes Capable of Electrochemically Stable Operation at 100 ℃

In-situ polymerized acrylate-based polymers are very appealing as solid polymer electrolytes (SPEs) in lithium (Li) batteries due to the drop-in compatibility of such in-situ polymerization with conventional battery production, the ease of acrylate polymerization and their inexpensive, facile SPE chemistry. We identified, however, that such SPEs suffer from either a low cationic transference number with dual ion conducting salts (0.12-0.2) or a low ionic conductivity with single Li-ion conducting (SLIC) salts (6·10-6 S cm-1). In this project we overcame these limitations and developed significantly improved SPE with ionic conductivity of up to 2·10-4 Scm-1 and a relatively high Li-ion transference number of 0.4. With a significantly reduced fraction of mobile anions in the hybrid SPE, in-situ polymerized SPE cells with an LiFePO4 (LFP) cathode achieve a stable performance for over 100 cycles at temperatures as high as 100 °C, which is unattainable with conventional Li salts or electrolytes. Furthermore, the motional narrowing observed in the line-shapes of solid-state nuclear magnetic resonance (SS-NMR) spectra provided additional insights of the differences in Li nucleus environments and revealed a reduced activation energy for the hybrid salt SPEs due to their more open structure. This study opens the path for the fabrication of high-performance solid polymer lithium batteries capable of operating at high temperatures using commercial battery fabrication equipment. We expect that further tuning of the acrylate based SPE composition may allow further increases in its conductivity without sacrifices in its electrochemical stability or mechanical properties.