Mixed Character Research Articles

Nitrogen Complex-Driven Vacancy Cluster in Group-III Nitrides.

A series of experiments have elucidated the primary defects in group-III nitride epilayers, identifying vacancy clusters due to cation migration at interfaces to mitigate strained lattice. While the occurrence of these defects is well-documented, the underlying electronic mechanisms driving vacancy agglomeration in nitrides and their alloys remain poorly understood. In this study, we uncovered a previously unreported ground state of two metal vacancies driven by the migration of kinetically unstable nitrogen atoms using an ab initio approach. Our findings reveal that the mixed covalent-ionic bond character of nitrides is a crucial factor in determining the stability of vacancy clusters. Notably, the relatively strong ionic character of AlN facilitates the formation of exceptionally stable vacancy clusters with a pyramidal nitrogen complex. In contrast, GaN, despite having similar covalent bonding strength, exhibits less stable vacancy clusters due to its weaker ionic character. Moreover, in InN, we observe the formation of molecular-like azide anion that creates a trimer metallic-like bond between indium dangling bonds, accompanied by vigorous indium migration. In the process, we newly identified the formation of a Schottky-Frenkel composite defect. We believe that these novel insights into the bond character and stability of vacancy clusters in nitrides provide a new understanding that could drive the design and optimization of nitride-based materials and electronic devices.

Narrow Band Gap Base Metal Double Perovskite Oxides Through Copper Doping of Ba2Ca0.66Nb1.33O6

This work examines the influence of copper doping on the structure, optoelectronic properties, and photocatalytic performance of transition metal double perovskite oxides of the Ba2Ca0.67Nb1.33O6 (BCN) family. A solid-state synthesis method was used to achieve partial substitution of Cu2+ in the Nb5+ site (Ba2Ca0.67Nb1.33-xCuxO6-δ, x = 0.05, 0.13, 0.26) and Ca2+ site (Ba2Ca0.67-xCuxNb1.33O6-δ, x = 0.13). The incorporation of copper in BCN resulted in significant changes in the structure and optoelectronic properties. Major differences were observed when Cu atoms occupied the Nb-site versus the Ca-site. The parent compound and Ca-site doped compounds crystallized in a P3 1 space group while Nb-site doped compounds showed increasing Fm3 mixed phase character. Cu doping resulted in a dramatic shift of the absorption band edge towards the visible region. Ca-site doping resulted in a primary band edge shift from 3.8 eV to 2.1. For the Nb-site doped compounds, the primary band-edge remained at 3.8 eV but a secondary band-edge appeared which progressively shifted to smaller energies as Cu doping increased. Ba2Ca0.67Nb1.20Cu0.13O6-δ and Ba2Ca0.67Nb1.07Cu0.26O6-δ exhibited strong absorption of near-infrared photons of wavelength well beyond 800 nm. The double perovskite oxides were utilized as photoanodes for photoelectrochemical water splitting, exhibiting both a visible photoresponse (until wavelengths as low as 520 nm) and good photochemical stability. This work showcases the possibility of forming new low band gap multi-element inorganic semiconductor oxides constituted entirely of base metals and oxygen.

Vibrational Fermi Resonance in Atomically Thin Black Phosphorus.

Fermi resonance is a phenomenon involving the hybridization of two coincidentally quasi-degenerate states that is observed in the vibrational or electronic spectra of molecules. Despite numerous examples in molecular systems, vibrational Fermi resonances in dispersive semiconducting systems remain largely unexplored due to the rarity of occurrence. Here we report a vibrational Fermi resonance in atomically thin black phosphorus. The Fermi resonance arises via anharmonic mixing of a fundamental Raman mode and a Davydov component of an infrared mode, leading to a doublet with mixed character. The extent of Fermi coupling can be modulated by the application of external biaxial strain. The consequences of Fermi hybridization are revealed by electronic resonance effects in the thickness-dependent and excitation-wavelength-dependent Raman spectrum, which is predicted by ab initio hybrid functional simulations including excitonic interactions. This work reveals new insight into electron-phonon coupling in black phosphorus and demonstrates a novel method for modulating Fermi resonances in 2D semiconductors.

Metallogenic model of the Lykling ophiolite-hosted lode Au deposit, Scandinavian Caledonides: Insight from fluid inclusions, mineral chemistry and stable isotope geochemistry

The Lykling lode Au deposit represents a unique example of gold mineralization in the Upper Allochthone of the Scandinavian Caledonides. The mineralization is hosted by the Early Ordovician Lykling Ophiolite Complex and the intruding trondhjemite unit and spatially associated with two generations of mafic dykes that crosscut both the ophiolitic complex and trondhjemite. Field observations indicate that the mafic dykes did not play an active role in the emplacement of Au at Lykling, however their contacts with the immediate host rocks (i.e., gabbro and trondhjemite) may have focused ore-forming fluids.Three main stages in the evolution of the hydrothermal system in the Lykling area are documented by two generations of auriferous quartz veins: 1) older quartz-carbonate veins hosted by moderately angled brittle-ductile shear zones and 2) younger quartz-sulfide veins that fill steeply dipping brittle faults. Stage 1 resulted in deposition of barren quartz and gold-free pyrite from moderately saline NaCl-CaCl2-H2O ± CO2 fluids at temperatures between ∼310–330 °C and pressures in the range from 2.7 to 3.5 kbars. Under the given physicochemical conditions Au was mobile in the form of its chloride complexes. Stage 2 is associated with multiple episodes of ductile deformation punctuated by concomitant brecciation reflecting brittle-ductile transition processes. Fluid inclusion data reveals a decrease in temperature and pressure that may result in the formation of stable Au-bisulfide complexes and making the hydrothermal mobility of Au sensitive to changes in pressure. Consequently, the fluctuation in pressure controlled by the development of brittle-ductile structures likely resulted in the precipitation of native gold in quartz veins. Stage 3 represents a pure brittle event which is accompanied by a significant decrease in the fCO2/fS2 ratio. Mixing of higher-temperature and moderate-salinity fluids with cooler fluids has been recognized as the principal trigger for deposition of sulfides and a paragenetically late phase of native gold in the Lykling hydrothermal system.The Lykling ophiolite-hosted lode Au deposit shows numerous similarities with orogenic gold deposits elsewhere, including structural controls during mineralizing events, deposition from moderately to low salinity CO2-bearing aqueous solutions, deposition from a focused fluid flow along trans-crustal fault zones with a mixed brittle-ductile character and the spatial association with regionally metamorphosed terranes. In contrast to the great majority of the known orogenic gold deposits, the Lykling ophiolite-hosted lode Au deposit records a magmatic origin of volatiles. Therefore, taking into consideration field relationships and the regional setting of the Lykling deposit, we argue that its formation is concomitant with emplacement of the Sunnhordland Batholith during post-collisional thinning of the crust and associated localized uplift within the Lykling Ophiolite Complex.

Cisuralian plant fossils from Khenifra (Central Morocco): Palaeoenvironmental and palaeobiogeographical reconstructions

This study focuses on newly collected plant fossils from the Cisuralian successions of the Khenifra Basin in Central Morocco, revealing a diverse assemblage dominated by conifers, pteridosperms, and sphenophytes. The assemblage includes eleven taxa of vegetative and reproductive organs preserved as compressions and impressions. Two pteridosperm species taxa (Neurodontopteris auriculata, Odontopteris subcrenulata) are recorded for the first time from Central Morocco, whereas other taxa are known from the early Permian deposits of Bou Achouch and Tiddas basins. Contrary to previous interpretations, the flora is does not exhibit a mixed character, but instead exhibits a distinct Euramerican affinity, despite the absence of the widespread callipterids Autunia conferta and A. naumannii. These similarities between this flora and coeval Euramerican floras highlight the significant biogeographical connections across Pangea during the Cisuralian. The plant fossil assemblage is dominated by meso- to xerophilous species adapted to drought, with rare hygrophilous elements adapted to humid habitats, reflecting a heterogeneous landscape with various vegetation types.

Chemical Trends of the Bulk and Surface Termination-Dependent Electronic Structure of Metal-Intercalated Transition Metal Dichalcogenides.

The addition of metal intercalants into the van der Waals gaps of transition metal dichalcogenides has shown great promise as a method for controlling their functional properties. For example, chiral helimagnetic states, current-induced magnetization switching, and a giant valley-Zeeman effect have all been demonstrated, generating significant renewed interest in this materials family. Here, we present a combined photoemission and density-functional theory study of three such compounds: , , and , to investigate chemical trends of the intercalant species on their bulk and surface electronic structure. Our resonant photoemission measurements indicate increased hybridization with the itinerant NbS2-derived conduction states with increasing atomic number of the intercalant, leading to pronounced mixing of the nominally localized intercalant states at the Fermi level. Using spatially and angle-resolved photoemission spectroscopy, we show how this impacts surface-termination-dependent charge transfers and leads to the formation of new dispersive states of mixed intercalant-Nb character at the Fermi level for the intercalant-terminated surfaces. This provides an explanation for the origin of anomalous states previously reported in this family of compounds and paves the way for tuning the nature of the magnetic interactions in these systems via control of the hybridization of the magnetic ions with the itinerant states.

Occupied-Virtual Orbitals for Chemical Valence with Applications to Charge Transfer in Energy Decomposition Analysis.

In this article, we introduce the occupied-virtual orbitals for chemical valence (OVOCV). The OVOCVs can replace or complement the closely related idea of the natural orbitals for chemical valence (NOCV). The input is a difference density matrix connecting any initial single determinant to any final determinant, at a given molecular geometry, and a given one-particle basis. This arises in problems such as orbital rearrangement or charge transfer (CT) in energy decomposition analysis (EDA). The OVOCVs block-diagonalize the density difference operator into 2 × 2 blocks, which are spanned by one level that is filled in the initial state (the occupied OVOCV) and one that is empty (the virtual OVOCV). By contrast, the NOCVs fully diagonalize the density difference matrix and therefore are orbitals with mixed occupied-virtual character. Use of the OVOCVs makes it much easier to identify the donor and acceptor orbitals. We also introduce two different types of EDA methods with the OVOCVs and, most importantly, a charge decomposition analysis method that fixes the unreasonably large CT amount obtained directly from NOCV analysis. The square of the CT amount associated with each NOCV pair emerges as the appropriate value from the OVOCV analysis. When connecting the same initial and final states, this value is identical to the CT amount obtained from the independent absolutely localized molecular orbital (ALMO) complementary occupied-virtual orbital pair (COVP) analysis. The total, summed over all pairs, is also exactly the same as the independently suggested excitation number, as proved herein. Several examples are presented to compare NOCVs and OVOCVs: stretched H2+, a strong halogen bond between tetramethylthiourea and iodine, coordination of ethene in Zeise's salt, and binding in the Cp3La···C≡NCy complex.

Control or Compensation: Distorted Narrative and Aftermath of Article 17 CDSM

Abstract This article analyses the value gap argument and the legislative outcome of Art. 17 of the Directive on copyright in the Digital Single Market (CDSM). The analysis is based on a qualitative content analysis of key documents related to the value gap problem and entitlement analysis of the property and liability rules character of Art. 17. The central theme of this article is the conflict between control and compensation. This ties into Peukert’s communication culture concept, which emphasizes exclusivity or access. Control and compensation are vital elements in the property and liability rules framework. The first part explores the roots of the value gap argument and its connection to the proprietary paradigm of copyright. The content analysis of the value gap argument shows that it is built upon the property narrative of copyright. The second part examines Art. 17 through the lens of property and liability rules, drawing on the framework developed by Calabresi and Melamed. The results show that Art. 17 has a mixed character, with a dominant property rule. However, when the real market dynamics are considered, the analysis reveals different results in different creative industries. Industries with strong collective management presence operate under liability rule schemes. As a result, authors in these industries benefit from ‘compensation without control’. The article concludes that integrating liability rule mechanisms is crucial for promoting access and fair compensation. This is exemplified by Art. 17 and markets that function under liability rule organizations, where minor authors particularly stand to benefit.

Bark thickness and related parameters of tree species along an elevation transect leading to treeline in Central Himalaya.

Since treelines are generally fire-free, the trees growing there are expected to have thin bark, unless adaptation to other factors than fire results in the selection of a thick bark. Related to this is also higher proportional investment in inner bark in such an environment of infrequent fire. This study has considered stem bark thickness both in absolute and relative terms and also in the frame of the composition of outer and inner bark components of 20 tree species along an elevation transect (2100-3300m) in high ranges of the Central Himalaya leading to treelines. The study species varied from 2.1 to 16.2mm for total bark thickness and from 1.2 to 18.85% for relative bark thickness. The average absolute total bark thickness across the tree species decreased with elevation from forest to treeline, both when trees of all diameters (10.2 ± 0.84mm for forest and 6.9 ± 1.79mm for treeline) and those of the same stem diameter range (18-20m) were compared (9.10 ± 1.30mm for forest species and 6.38 ± 1.31mm for treeline species). Nevertheless, the treeline bark thickness was similar to those of several forest communities considered to have comparatively thick bark. Like many other biological structures, bark carries out multiple functions; therefore, its thickness could be affected by more than one environmental factor. We suggest that the requirement of mechanical resistance to the snowfall, rainstorms, wind and adaptation to a high sunlight and UV radiations or storage of water, and non-structural carbohydrates could affect total, outer and inner bark thickness. Studies on these aspects in similar ecosystems may help understand the multi-functional attributes of the bark. For trees of comparable sizes (trees with 18-20cm diameter at breast height) treeline species also had lower relative bark thickness (< 6%) than trees of forest below it (> 7%). The median proportion of inner bark of the total bark (70.5%) for our 20 species was more than that for savannas (~ 50%), exposed to frequent fire regime and similar to those of in cool sclerophyllous forests and temperate rain forests where fire return time is > 100years. However, it was lower than the inner bark proportion reported for tropical rain forests. To conclude, in spite of a fire-free environment, the Himalayan treeline and adjoining forest species show mixed bark characters.

A Janus carbaporphyrin pseudo-dimer

Carbaporphyrin dimers, investigated for their distinctive electronic structures and exceptional properties, have predominantly consisted of systems containing identical subunits. This study addresses the associated knowledge gap by focusing on asymmetric carbaporphyrin dimers with Janus-like characteristics. The synthesis of a Janus-type carbaporphyrin pseudo-dimer 5 is presented. It displays antiaromatic characteristics on the fused side and nonaromatic behavior on the unfused side. A newly synthesized tetraphenylene (TPE) linked bis-dibenzihomoporphyrin 8 and a previously reported dibenzo[g,p]chrysene (DBC) linked bis-dicarbacorrole 9 were prepared as controls. Comprehensive analyses, including 1H NMR spectral studies, single crystal X-ray diffraction analyses, and DFT calculations, validate the mixed character of 5. A further feature of the Janus pseudo-dimer 5 is that it may be transformed into a heterometallic complex, with one side coordinating a Cu(III) center and the other stabilizing a BODIPY complex. This disparate regiochemical reactivity underscores the potential of carbaporphyrin dimers as versatile frameworks, with electronic features and site-specific coordination chemistry controlled through asymmetry. These findings position carbaporphyrin dimers as promising candidates for advances in electronic structure studies, coordination chemistry, materials science, and beyond.

A new hemeroscopid dragonfly (Odonata, Anisoptera) from the Lower Cretaceous of the Jiuquan Basin, northwestern China

A new hemeroscopid dragonfly, Parahemeroscopus jiuquanensis gen. et sp. nov., is described from the Lower Cretaceous Zhonggou Formation of the Jiuquan Basin, northwestern China. Parahemeroscopus gen. nov. has the mixed characters of the hemeroscopid genera Hemeroscopus Pritykina, 1977 and Abrohemeroscopus Ren, Liu &amp; Cheng, 2003, and probably represents a transitional dragonfly from Abrohemeroscopus to Hemeroscopus. The new finding not only adds to the diversity of the Hemeroscopidae Pritykina, 1977, but also provides clues for revealing the early evolution of the hemeroscopid dragonflies.

Fossil Signatures of Main-sequence Convective Core Overshoot Estimated through Asteroseismic Analyses

Some physical processes that occur during a star's main-sequence evolution also affect its post-main-sequence evolution. It is well known that stars with masses above approximately 1.1 M ⊙ have well-mixed convective cores on the main sequence; however, the structure of the star in the neighborhood of the convective core regions is currently underconstrained. We use asteroseismology to study the properties of the stellar core, in particular convective boundary mixing through convective overshoot, in such intermediate-mass stars. These core regions are poorly constrained by the acoustic (p) mode oscillations observed for cool main-sequence stars. Consequently, we seek fossil signatures of main-sequence core properties during the subgiant and early first-ascent red giant phases of evolution. During these stages of stellar evolution, modes of mixed character that sample the deep interior can be observed. These modes sample the parts of the stars that are affected by the main-sequence structure of these regions. We model the global and near-core properties of 62 subgiant and early first-ascent red giant branch stars observed by the Kepler, K2, and TESS space missions. We find that the effective overshoot parameter, α ov,eff, increases from M = 1.0 M ⊙ to M = 1.2 M ⊙ before flattening out, although we note that the relationship between α ov,eff and mass will depend on the incorporated modeling choices of internal physics and nuclear reaction network. We also situate these results within existing studies of main-sequence convective core boundaries.

Unveiling Multiquantum Excitonic Correlations in Push-Pull Polymer Semiconductors.

Bound and unbound Frenkel-exciton pairs are essential transient precursors for a variety of photophysical and biochemical processes. In this work, we identify bound and unbound Frenkel-exciton complexes in an electron push-pull polymer semiconductor using coherent two-dimensional spectroscopy. We find that the dominant A0-1 peak of the absorption vibronic progression is accompanied by a subpeak, each dressed by distinct vibrational modes. By considering the Liouville pathways within a two-exciton model, the imbalanced cross-peaks in one-quantum rephasing and nonrephasing spectra can be accounted for by the presence of pure biexcitons. The two-quantum nonrephasing spectra provide direct evidence for unbound exciton pairs and biexcitons with dominantly attractive force. In addition, the spectral features of unbound exciton pairs show mixed absorptive and dispersive character, implying many-body interactions within the correlated Frenkel-exciton pairs. Our work offers novel perspectives on the Frenkel-exciton complexes in semiconductor polymers.

FCC-Zr phase transformation-induced defect substructure in Zr2Si precipitates equilibrated in Si-modified Zircaloy-4

This work investigates the atomic scale substructure of interfaces in Zr2Si secondary phase precipitates formed by the stresses associated with the α-Zr (HCP) to γ-Zr (FCC) phase transformation and thermal effects in an experimental Si-modified Zircaloy-4 by means of transmission electron microscopy and CSL/DSCL (coincident site lattice/displacement shift complete lattice) models. Analysis of a high-angle twin interface reveals their characteristic principal primary Δg vectors, a typical feature of the singular interfaces, and the sessile twinning disconnections. The step height and length of the interfacial dislocation line, with the Burgers vector parallel to the habit plane, are analysed using the DSCL model. In the second case, a low-angle interface of mixed tilt-twist character is studied and facets of constant length along the densest-packed planes and ledges of inconstant height, a common feature of vicinal interfaces, are identified.

What is the effect of reducing the air change rate on the ventilation effectiveness in ultra-clean operating rooms?

The operating room (OR) department is one of the most energy-intensive departments of a hospital. The majority of ORs in the Netherlands have an air-handling installation with an ultra-clean ventilation system. However, not all surgeries require an ultra-clean OR. To determine the effect of reducing the air change rate on the ventilation effectivenessin ultra-clean ORs. Lower air volume ventilation effectiveness (VELv) of conventional ventilation (CV), controlled dilution ventilation (cDV), temperature-controlled airflow (TcAF) and unidirectional airflow (UDAF) systems were evaluated within a 4× 4m measuring grid of 1× 1m. The VELv was defined as the recovery degree (RD), cleanliness recovery rate (CRR) and air change effectiveness (ACE). The CV, cDVLv and TcAFLv ventilation systems showed a comparable mixing characterin all areas (A, B and AB) when reducing the air change rate to 20/h. Ventilation effectiveness decreased when the air change rate was reduced, with the exception of the ACE. At all points for the UDAF-2Lv and at the centre point (C3) of the TcAFLv, higher RD10Lv and CRRLv were measured when compared with the other examined ventilation systems. The ventilation effectiveness decreased when an ultra-clean OR with an ultra-clean ventilation air-supply system was switched to an air change rate of 20/h. Reducing the air change rate in the OR from an ultra-clean OR to a generic OR will reduce the recovery degree (RD10) by a factor of 10-100 and the local air change rate (CRR) by between 42% and 81%.

Features of hydrogen cracking process of heat-strengthened reinforcing steels

The effect of heat treatment of reinforcing steels of St5, 18GS, 20GS, 23Kh2G2Ts, 30GST and 35GS grades on the change in their resistance to hydrogen cracking is considered. For St5 steel, it was found that an increase in the tempering temperature contributes to an increase in resistance to cracking by obtaining a highly plastic structure with an increased ability to relax internal microstresses. For 30GST and 35GS steels, optimal heat treatment modes are determined to ensure their resistance to hydrogen cracking. For 30GST steel, this mode is quenching from 900 °C with cooling in water + tempering with electrical heating at 500 °C, and for 35GS steel — triple heat treatment of the type of intercritical quenching from temperatures of 900/700 °C or 800/700 °C, followed by tempering at temperatures of 300 or 400 °C, respectively and heat treatment from 900 °C with double tempering (from 400 °C (furnace heating) and 500 °C (electrothermal hardening)). The features of the destruction process of reinforcing steels in an environment causing hydrogen cracking are considered. It is shown that the propagation of corrosion cracks has a mixed character (transcrystalline and intercrystallite).

Detailed quasiclassical dynamics of the F- + SiH3Cl multi-channel reaction.

We report a detailed quasiclassical trajectory study on the F- + SiH3Cl multi-channel reaction using a full-dimensional ab initio analytical potential energy surface. Reaction probabilities, cross sections, initial attack and scattering angle distributions as well as product relative translational, internal, vibrational, and rotational energy distributions are obtained in the collision energy range of 1-40 kcal mol-1 for the following channels: SiH3F + Cl-, SiH2Cl- + HF, SiH2F- + HCl, SiH2FCl + H-, SiH2 + FHCl-, and SiHFCl- + H2. All the channels are translationally cold indicating indirect mechanisms, except proton transfer (SiH2Cl- + HF), which shows mixed direct-indirect character. The angular distributions vary depending on collision energy and inversion/retention for SiH3F + Cl-. In the case of SiH2Cl- + HF front-side/back-side attack backward-forward/forward scattering preference is found at low/high collision energy. SiH2F- + HCl is formed with isotropic scattering and the preferred angle of attack is similar to the SiH3F + Cl- channel. SiH2FCl + H-/SiH2 + FHCl- favors back-side attack and isotropic/backward scattering, whereas SiHFCl- + H2 does not show significant angular preference.

Locked differential rotation in core-helium burning red giants

Context. Oscillation modes of a mixed character are able to probe the inner region of evolved low-mass stars and offer access to a range of information, in particular, the mean core rotation. Ensemble asteroseismology observations are then able to provide clear views on the transfer of angular momentum when stars evolve as red giants. Aims. Previous catalogs of core rotation rates in evolved low-mass stars have focussed on hydrogen-shell burning stars. Our aim is to complete the compilation of rotation measurements toward more evolved stages, with a detailed analysis of the mean core rotation in core-helium burning giants. Methods. The asymptotic expansion for dipole mixed modes allows us to fit oscillation spectra of red clump stars and derive their core rotation rates. We used a range of prior seismic analyses, complete with new data, to get statistically significant results. Results. We measured the mean core rotation rates for more than 1500 red clump stars. We find that the evolution of the core rotation rate in core-helium-burning stars scales with the inverse square of the stellar radius, with a small dependence on mass. Conclusions. Assuming the conservation of the global angular momentum, a simple model allows us to infer that the mean core rotation and envelope rotation are necessarily coupled. The coupling mechanism ensures that the differential rotation in core-helium-burning red giants is locked.

Field induced metamagnetic transition and mixed charge transfer Mott-Hubbard character in nanocrystalline FeCo2O4 spinel oxide: A combined study using experimental and first principles techniques

Unusual magnetic behavior of nanocrystalline FeCo2O4 (FCO) has been observed at different annealing temperatures. FCO nanoparticles have been prepared by co-precipitation method and the prepared sample annealed at different temperatures to vary its crystallite size. The powder x-ray diffraction analysis confirms the presence of pure spinel phase in the samples annealed at 900 ℃ and 1000℃. The increase in particle size with annealing temperature has been confirmed by field emission scanning electron microscopy (FESEM) analysis. High resolution x-ray photoelectron spectroscopy (HRXPS) analysis reveals the presence of mixed oxidation states of Fe+2/ Fe+3 and Co+3/Co+2 in the sample annealed at 900℃. The as-synthesized sample at 80 °C shows strong antiferromagnetic behavior due to their smaller particle size, but all the annealed samples have strong ferromagnetic behavior with large coercive field and remanence due to their larger particle size. We have observed a sharp rise in magnetization near small field values in the virgin curve and also the presence of virgin curve completely outside the main hysteresis loop in the M(H) curves measured at 5 K for the samples annealed at and above 1000 ℃ reveal the characteristic of first order nature of field induced metamagnetic transition. Structural parameters obtained after Rietveld refinement of powder x-ray diffraction pattern for sample annealed at 900 ℃ have been used for investigating the magnetic properties using first principles density functional theory. Our calculations using hybrid exchange-correlation functional, HSE06 captures the correct insulating ferromagnetic ground state and band gap for inverse spinel structure in broad agreement with our experimental results while calculations within GGA+U leads to a wrong half metallic ferromagnetic ground state. The partial density of states obtained for inverse spinel structure with HSE06 functional suggests a mixed charge transfer and Mott-Hubbard character in our system. We have explored the interplay among structural, magnetic and transport properties of FCO using experiment as well as first principles density functional theory.

The Mixed Homonymic Characters: Procedures for Primary Teaching as Recommended by the Tanguts

The newly discovered Tangut xylograph Essential Selection of Mixed Homonyms Often-Transmitted is a primer designed to teach beginners over 2000 Tangut characters commonly used in Buddhist scriptures. Referring to various dictionaries and primers, the compilation approach of the booklet is modeled after the Chinese traditional primer entitled Mixed Characters, which was widely circulated at that time, but its notes focus on the interchangeability of homonymic characters in various manuscripts, rather than on providing phonetic or semantic explanations. The two prefaces of the book prove to be a unique material for showing how the Tanguts treated their own script, and how a Tangut teacher taught beginners to read and write such complex characters. Unfamiliar with the Chinese concept of radicals, the Tanguts regarded their characters as combinations of various components formed by simplest strokes and glyphs. They believed that it would be easier for students to learn Tangut characters by piecing the components together than trying to write full characters directly. Complete translations of the two prefaces to the book are presented for the first time in this paper.