X-ray Studies Research Articles

High Resolution Images of Human Meibum Spread on Saline.

Understanding of the role of the tear film lipid layer (TFLL) in evaporative dry eye requires knowledge of its structure. X-ray studies show 11.1-nm thick lamellae in meibum at tear film temperature (approximately 35°C), whereas below 30°C, 4.88-nm thick lamellae predominate. Here, high resolution microscopy of meibum spread on saline is studied as a function of temperature, to compare with x-ray results. A purpose-built high resolution color microscope, previously used to study the TFLL, was used to study meibum from 10 subjects. It was spread on buffered saline at near 40°C, and allowed to cool to room temperature. Analytical methods from previous studies were applied to measure meibum and lamellar thickness. Initially, an irregular "island" was formed, surrounded by a "background layer" of 7.8 ± 0.3 nm thickness. Dewetting of the meibum layer always occurred, leading to the formation of lens-shaped droplets. Below 30°C, the lenses start to emit "tails" having a multilamellar structure containing up to about 49 lamellae superimposed on the background layer, each lamella being 4.82 ± 0.13 nm thick. Below 30°C, meibum spread on saline shows a multilamellar structure like the 4.88 nm thickness in x-ray studies, demonstrating the ability to observe and measure tightly stacked lamellae. In contrast, above 30°C, the 11.1 nm lamellae were not observed as in x-ray studies, indicating that these lamellae were not tightly stacked but may be separated by disordered lipid. The role of these findings in evaporative dry eye is discussed.

Geminga's pulsar halo: An X-ray view

Geminga is the first pulsar around which a remarkable gamma-ray halo extending over a few degrees was discovered at TeV energies by MILAGRO and HAWC and later by H.E.S.S., and by -LAT in the GeV band. More middle-aged pulsars have exhibited gamma-ray halos, and they are now recognised as an emerging class of Galactic gamma-ray sources. The emission appears in the late evolution stage of pulsars, and is most plausibly explained by inverse Compton scattering of CMB and interstellar photons by relativistic electrons and positrons escaping from the pulsar wind nebulae. These observations pose a number of theoretical challenges, particularly the origin of the inferred, significantly lower effective diffusion coefficients around the pulsar when compared to typical Galactic values. Tackling these questions requires constraining the ambient magnetic field properties, which can be achieved through X-ray observations. If the gamma-ray halos originate from a distribution of highly energetic electrons, synchrotron losses in the ambient magnetic fields of the same particles are expected to produce a diffuse X-ray emission with a similar spatial extension. We present the most comprehensive X-ray study of the Geminga pulsar halo to date, utilising archival data from and . Our X-ray analysis covers a broad bandwidth ($0.5 79$ keV) and large field of view ($ for the first time. This was achieved by accurately measuring the background over the entire field of view, and taking into account both focused and stray-light X-ray photons from the pulsar halo with . We find no significant emission and set robust constraints on the X-ray halo flux. These are translated to stringent constraints on the ambient magnetic field strength and the diffusion coefficient by using a physical model considering particle injection, diffusion, and cooling over the pulsar’s lifetime, which is tuned by fitting multi-wavelength data. Our novel methodology for modelling and searching for synchrotron X-ray halos can be applied to other pulsar halo candidates.

Tunable charge transport properties in non-stoichiometric SrIrO3 thin films

Delving into the intricate interplay between spin-orbit coupling and Coulomb correlations in strongly correlated oxides, particularly perovskite compounds, has unveiled a rich landscape of exotic phenomena ranging from unconventional superconductivity to the emergence of topological phases. In this study, we have employed pulsed laser deposition technique to grow SrIrO3 (SIO) thin films on SrTiO3 substrates, systematically varying the oxygen content during the post-deposition annealing. X-ray photoelectron spectroscopy (XPS) provided insights into the stoichiometry and spin-orbit splitting energy of Iridium within the SIO film, while high-resolution x-ray studies meticulously examined the structural integrity of the thin films. Remarkably, our findings indicate a decrease in the metallicity of SIO thin films with reduced annealing O2 partial pressure. Furthermore, we carried out magneto-transport studies on the SIO thin films, the results revealed intriguing insights into spin transport as a function of oxygen content. The tunability of the electronic band structure of SIO films with varying oxygen vacancy is correlated with the density functional theory calculations. Our findings elucidate the intricate mechanisms dictating spin transport properties in SIO thin films, offering invaluable guidance for the design and optimization of spintronic devices based on complex oxide materials. Notably, the ability to tune bandwidth by varying post-annealing oxygen partial pressure in iridate-based spintronic materials holds significant promise for advancing technological applications in the spintronics domain.

Impact of carbon dots on the structural, morphological, magnetic, and electrochemical performance of Zn ferrite for energy storage applications

Magnetic core-shell Zn ferrite and carbon dots (C-dots) composite have been synthesized in this work using a simple coprecipitation and hydrothermal process, respectively. X-ray diffraction (XRD) patterns demonstrate an inverse spinel structure of Zn ferrites; the lattice parameter has decreased from 8.19 Å to 8.10 Å with C-dots. Scanning electron microscopy (SEM) images reveal rods-like structures for C-dots, and in the composite case, it is uniformly dispersed using low contrast consecutive C-dot layers to produce a core-shell structure. Zn ferrites are non-uniform in size, whereas C-dots and their composites are in uniform shape according to SEM images. The energy dispersive X-ray (EDX) study indicates that the substitution has been successful. For Zn ferrites, and composite, the Fourier transform infrared (FTIR) spectra shows that the absorption band of the tetrahedral site at 990 cm−1, and 870 cm−1, respectively. Different bonds in the infrared spectrum match specific function groups and bonding in various chemicals. The vibrating sample magnetometry (VSM) results indicates that the composite displays ferrimagnetic behavior. The specific capacity for composite has been found to be 2351 and 1790 F/g using cyclic voltammetry (CV) and galvanostatic charge-discharge (GCD) measurements, respectively. Higher electrochemical performance of the prepared composites may be helpful for energy storage systems.

High-Temperature Stirring Pretreatment of Waste Rubber Particles Enhances the Interfacial Bonding and Mechanical Properties of Rubberized Concrete

This paper innovatively proposes a method of 180 °C high-temperature stirring pretreatment for waste rubber particles and compares this method with untreated, NaOH-treated, and silane coupling agent KH570-treated waste rubber particles. Fourier-transform infrared spectroscopy, X-ray diffraction analysis, water contact angle measurement, scanning electron microscopy, and energy-dispersive X-ray study are used to investigate the effects and mechanisms of different pretreatment methods on waste rubber particles. The results indicate that compared to NaOH-treated and KH570-treated waste rubber particles, the 180 °C high-temperature-stirred pretreated waste rubber particles show significantly improved cleanliness and form a hard oxide film. The study also investigates the effects of different pretreatment methods on the mechanical properties and interface binding performance of rubber concrete made from pretreated waste rubber particles. The results demonstrate that rubber concrete prepared using 180 °C high-temperature-stirred pretreated waste rubber particles substituting 20% fine aggregate exhibits the best mechanical properties and interface bonding performance. The compressive strength recovery rates after 7 and 28 days are 41.6% and 37.3%, respectively; the split tensile strength recovery rates are 47.3% and 60.6%; the axial compressive strength recovery rates are 34.1% and 18.8%; and the static compression moduli of elasticity recovery rates are 46.8% and 26.3%. High-temperature stirring pretreatment of waste rubber particles is simple to operate and suitable for scaled production. Its pretreatment effect is superior to those of the KH570 and NaOH methods, providing a reference value for the scalable application of waste rubber particles as a substitute for fine aggregate in rubber concrete.

The Physalis system: discovery of ORC-like radio shells around a massive pair of interacting early-type galaxies with offset X-ray emission

ABSTRACT We present the discovery of large radio shells around a massive pair of interacting galaxies and extended diffuse X-ray emission within the shells. The radio data were obtained with the Australian Square Kilometre Array Pathfinder (ASKAP) in two frequency bands centred at 944 MHz and 1.4 GHz, respectively, while the X-ray data are from the XMM–Newton observatory. The host galaxy pair, which consists of the early-type galaxies ESO 184-G042 and LEDA 418116, is part of a loose group at a distance of only 75 Mpc (redshift $z = 0.017$). The observed outer radio shells (diameter ${\sim}$145 kpc) and ridge-like central emission of the system, ASKAP J1914−5433 (Physalis), are likely associated with merger shocks during the formation of the central galaxy (ESO 184-G042) and resemble the new class of odd radio circles (ORCs). This is supported by the brightest X-ray emission found offset from the centre of the Physalis system, instead centred at the less massive galaxy, LEDA 418116. The host galaxy pair is embedded in an irregular envelope of diffuse light, highlighting ongoing interactions. We complement our combined radio and X-ray study with high-resolution simulations of the circumgalactic medium (CGM) around galaxy mergers from the Magneticum project to analyse the evolutionary state of the Physalis system. We argue that ORCs/radio shells could be produced by a combination of energy release from the central active galactic nucleus and subsequent lightening up in radio emission by merger shocks travelling through the CGM of these systems.

Novel Octahedral Nickel (II) Complex with Flexible Piperazinyl Moiety Exhibits Potent Cytotoxic Effect Along with Anti-Migratory and Anti-Metastatic Effect on Human Cancer Cells.

Synthesis of non-platinum transition metal complexes with N,O donor chelating ligand for application against pathogenesis of cancer with higher efficacy and selectivity is currently an important field of research. We assessed the anti-cancer effect of a mixed ligand Ni(II) complex on human breast and lung cancer cell lines in this investigation. Mononuclear mixed ligand octahedral Ni(II) complex [NiIIL(NO3)(MeOH)] complex (1), with tri-dentate phenol-based ligand 2,4-dichloro-6-((4-methylpiperazin-1-yl) methyl) phenol (HL) along with methanol and nitrate as ancillary ligand was prepared. Piperazine moiety of the ligand exists as boat conformation in this complex as revealed from single crystal X-ray study. UV-visible spectrum of complex (1) exhibits three distinct d-d bands due to spin-allowed 3 A2 g→3T1 g (P), 3 A2 g→3T1 g(F) and 3 A2 g→3T2 g(F) transitions as expected in an octahedral d8 system. Our study revealed that Complex (1) induces apoptotic cell death in mouse and human cancer cells such as mcf-7, A549 and MDA-MB-231 through transactivation of p53 and its pro-apoptotic downstream targets in a dose dependent manner. Furthermore, complex (1) was able to slow the migratory rate of MDA-MB-231 cells' in vitro as well as epithelia -mesenchymal transition (EMT), the key step for metastatic transition and malignancy. Over all our results suggest complex (1) as a potential agent in anti-tumor treatment regimen showing both cytotoxic and anti-metastatic activity against malignant neoplasia.

The Electric Conductivity of Bi7Fe3Ti3O21 Doped with Gadolinium.

Bi7-xGdxFe3Ti3O21 (x = (0, 0.2, 0.4, 0.6)) bismuth-layered perovskite structure compounds have been successfully prepared by a solid-state reaction. The results of X-ray studies indicate that a single-phase ceramic was obtained, characterized by an orthorhombic crystal structure for all compounds within the Fm2m space group. Microstructural analysis revealed that introducing gadolinium to the material altered the grain morphology, resulting in a more rounded grain shape and a somewhat disordered arrangement. Moreover, with higher gadolinium concentrations, there is a noticeable increase in the presence of the number of large plates. Impedance spectroscopy has been used to characterize the electrical properties of Bi7-xGdxFe3Ti3O21 compounds.

X-ray study on the core collapse supernova 2008ax using XMM-Newton and Swift/XRT

We studied the x-ray evolution of the core collapse, Type IIb, supernova SN 2008ax. In addition to the four Swift/XRT observations previously published, we included, for the first time, two observations from XMM-NEWTON to our analysis that have not been published before. By focusing on the early observations of the SN 2008ax, we were able to explore the time evolution of both x-ray luminosity (Lx) and temperature (Tx) during the radiative phase. The analysis showed that the evolution of Lx and Tx can be expressed as a power law as Lx ∝ t −0.87 and Tx ∝ t −0.46, respectively. Based on the observed x-ray luminosity, we estimated the mass-loss rate ( Ṁ ) for the progenitor star to be approximately 0.64 ± 0.15 × 10−5 M⊙ yr −1, for a wind velocity of 10 km s−1. This finding is in good agreement with the previous studies.

Thermal Formation of Metathesis-Active Tungsten Alkylidene Complexes from Cyclohexene.

A 7-tungstabicyclo[4.3.0]nonane complex forms slowly upon addition of cyclohexene to the ethylene complex, W(NAr)(OSiPh3)2(C2H4), at 22 °C. A single-crystal X-ray study showed its structure to be closest to a square pyramid (τ = 0.23). At 22 °C, loss of cyclohexene or ring contraction of the 7-tungstabicyclo[4.3.0]nonane complex is slow. Above ∼80 °C, cyclohexene is ejected to give W(NAr)(OSiPh3)2(C2H4), but a sufficient amount of 7-tungstabicyclo[4.3.0]nonane complex remains in the presence of cyclohexene and the ring contracts to yield methylenecyclohexane and a methylidene complex or ethylene and a cyclohexylidene complex. Other complexes that have been observed include an 8-tungstabicyclo[4.3.0]nonane complex formed from 1,7-octadiene, a 7-tungstabicyclo[4.2.0]octane complex (formed from a methylidene complex and cyclohexene), and a methylenecyclohexane complex. 13C-Labeling studies show that the exo-methylene group in methylenecyclohexane and the α positions in the 8-tungstabicyclo[4.3.0]nonane come from ethylene. An alternative ring contraction of a tungstacyclopentane made from two molecules of cyclohexene cannot be excluded when concentrations of ethylene are low. A cyclohexylidene complex could also form from two cyclohexenes via a newly proposed "alkyl/allyl" mechanism. The results reported here are the first experimental confirmations that a tungstacyclopentane can ring-contract thermally at a substituted WCα position to form a tungstacyclobutane and therefore metathesis-active alkylidenes.

Microscopy studies of InGaN MQWs overgrown on porosified InGaN superlattice pseudo-substrates

In this study, possible origins of small V-pits observed in multiple quantum wells (MQWs) overgrown on as-grown and porosified InGaN superlattice (SL) pseudo-substrates have been investigated. Various cross-sectional transmission microscopy techniques revealed that some of the small V-pits arise from the intersection of threading defects with the sample surface, either as part of dislocation loops or trench defects. Some small V-pits without threading defects are also observed. Energy dispersive x-ray study indicates that the Indium content in the MQWs increases with the averaged porosity of the underlying template, which may either be attributed to a reduced compositional pulling effect or the low thermal conductivity of the porous layer. Furthermore, the porous structure inhibits the glide or extension of the misfit dislocations (MD) within the InGaN SL. The extra strain induced by the higher Indium content and the hindered movement of the MDs combined may explain the observed additional small V-pits present on the MQWs overgrown on the more relaxed templates.

Synthesis and characterization of two Cu(II) complexes of new quinoline-based carboxylic acid

A new quinoline-based carboxylic acid called 3-benzoyl-2-oxo-1,2-dihydro-quinoline-4-carboxylic acid (HQC) (1a) was synthesized. In addition, one dimensional polymeric {[Cu(QC)2(BPE)2DMSO]}n.2DMSO.H2O (2) (BPE = 4,4′-ethylenebipyridine, DMSO = dimethyl sulfoxide) and dimeric [Cu2(QC)2(AcO)2(DMSO)2] (3) (QC = 3-benzoyl-2-oxo-1,2-dihydro-quinoline-4-carboxylate, AcO = Acetate ion) two Cu(II) complexes were synthesized by hydrothermal reaction. The structure of 1a was elucidated using elemental analysis and spectral techniques (NMR, UV–Vis and FTIR), while X-ray study, UV–Vis, FTIR, magnetic susceptibility and elemental analysis were used for complexes (2 and 3). X-ray analysis revealed that complex 2 has square-pyramidal geometry and complex 3 has octahedral geometry. From X-ray analysis for one dimensional coordination polymer 2, HQC (1a) was found to have a monodentate coordination mode. In contrast to 2, in dimeric complex 3, QC acts as a bidentate ligand, bridging two Cu(II) atoms.

Green Synthesis, Characterization, and Evaluation of Photocatalytic and Antibacterial Activities of Co3O4-ZnO Nanocomposites Using Calpurnia aurea Leaf Extract.

The green synthesis of transition metal oxide nanocomposites using plant extracts is a new and effective method that avoids the involvement of hazardous chemicals. Nondegradable organic pollutants and antibiotic drug resistance have become serious public health issues worldwide. Hence, the main objective of this study is to synthesize Co3O4-ZnO nanocomposites using Calpurnia aurea leaf extract and evaluate its photocatalytic and antibacterial activities. The green synthesized particles were characterized using UV-vis spectra, Fourier transform infrared spectroscopy, X-ray diffraction techniques, and scanning electron microscopy combined with energy-dispersive X-ray studies. The synthesized particles were found to be crystalline in nature with average crystallite sizes of 23.82, 14.79, 15.99, 16.46, and 21.73 nm. Scanning electron microscopy shows the spherical morphology of Co3O4-ZnO NCs, and energy-dispersive X-ray analysis confirms the formation of highly pure ZnO NPs and Co3O4-ZnO NCs. The photocatalytic activity was performed under natural sunlight using malachite green as an organic dye pollutant. The green synthesized ZnO NPs, Co3O4 NPs, 1:4, 1:3, and 1:2 Co3O4-ZnO NCs showed high degradation efficiency after 60 min of irradiation. The synthetic material showed good potential against Staphylococcus aureus and Escherichia coli, with the highest growth inhibition recorded by 1:2 Co3O4-ZnO NCs. The kinetics study of the photocatalytic degradation was confirmed as pseudo first order, and the possible mechanisms for both photocatalytic and antibacterial activities were clearly determined.

Thermal x-ray studies of neutron stars and the equation of state

Thermal x-ray studies of neutron stars and the equation of state

High-pressure X-ray study of NbON oxynitride: direct transition from baddeleyite to cotunnite structure

Abstract The structural properties of NbON oxynitride under high pressure were investigated through in situ synchrotron X-ray diffraction (SXRD) up to 43 GPa. It was found that the bulk modulus of baddeleyite NbON (290 GPa) is larger than that of ZrO2 (150 GPa), indicating that the introduction of highly covalent nitrogen imparts greater stiffness. Furthermore, SXRD patterns reveal the emergence of a peak signaling a new crystalline phase above around 20 GPa. This is in contrast to TaON, where diffraction patterns only show an increase in background beyond 33 GPa. First-principle calculations suggest that the high-pressure phase adopts an orthorhombic cotunnite-type structure, distinguishing it from the oxide counterparts, wherein the ambient pressure phase transforms to a cotunnite structure via an orthorhombic-I structure.

Phase-dependent Spectral Shape Changes in the Ultraluminous X-Ray Pulsar NGC 5907 ULX1

The discovery of coherent pulsations from several ultraluminous X-ray pulsars (ULXPs) has provided direct evidence of a supercritical accretion flow. However, the geometrical structure of such an accretion flow onto the central neutron star remains poorly understood. NGC 5907 ULX1 is one of the most luminous ULXPs, with a luminosity exceeding 1041 erg s−1. Here we present a broadband X-ray study of this ULXP using the data from simultaneous observations with XMM-Newton and NuSTAR conducted in 2014 July. The phase-resolved spectra are well reproduced by a model consisting of a multicolor disk blackbody emission with a temperature gradient of p = 0.5 (T ∝ r −p ) and a power law with an exponential cutoff. The disk component is phase-invariant and has an innermost temperature of ∼ 0.3 keV. Its normalization suggests a relatively low inclination angle of the disk, in contrast to the previous claims in other literature. The power-law component, attributed to the emission from the accretion flow inside the magnetosphere of the neutron star, indicates phase-dependent spectral shape changes; the spectrum is slightly harder in the pre-peak phase than in the post-peak phase. This implies that the magnetosphere has an asymmetric geometry around the magnetic axis and that hotter regions close to the magnetic pole become visible before the pulse peak.

X-ray study of the density distribution of FFF-printed samples with different fill patterns

Three-dimensional printing has a wide range of applications in science and technology. Fused filament fabrication (FFF) is a commonly used 3D printing technology, which is now being increasingly employed in radiation physics. In FFF, the internal structure of an object is primarily determined by its fill pattern and selected print modes. Therefore, this study aims to examine the interaction between X-rays and 3D-printed plastic samples with various infill patterns. The 3D-printed objects were produced using FFF with plastic and different infill patterns, including Rectilinear, Grid, Triangles, Stars, Honeycomb, Concentric, Archimedean Chords, Gyroid, and Hilbert Curve. Infill densities of 80% and 90% were utilized. Tomographic methods were applied to analyze the resulting samples. The study provides tomograms of the internal structure for each infill pattern. It was observed that Rectilinear and Grid patterns produced the most homogeneous samples. The findings of this study contribute to understanding of the propagation of X-rays through 3D-printed plastic samples with complex internal structures.

ЭЛЕКТРООСАЖДЕНИЕ ХРОМА ИЗ КИСЛЫХ ЭЛЕКТРОЛИТОВ С ДОБАВЛЕНИЕМ ОРГАНИЧЕСКИХ ПОВЕРХНОСТНО-АКТИВНЫХ ВЕЩЕСТВ

The influence of current density on the current efficiency of chromium, the content of organic additives on the microhardness and porosity of chromium deposits, and the thickness of chromium deposits on internal stresses were studied. X-ray studies of the structure of chromium deposits obtained from electrolytes with organic additives were carried out.

Low-mass Galaxy Interactions Trigger Black Hole Activity

The existence of high-z overmassive supermassive black holes represents a major conundrum in our understanding of black hole evolution. In this Letter, we probe from the observational point of view how early Universe environmental conditions could have acted as an evolutionary mechanism for the accelerated growth of the first black holes. Under the assumption that the early Universe is dominated by dwarf galaxies, we investigate the hypothesis that dwarf–dwarf galaxy interactions trigger black hole accretion. We present the discovery of 82 dwarf–dwarf galaxy pairs and 11 dwarf galaxy groups using the Hubble Space Telescope, doubling existing samples. The dwarf systems span a redshift range of 0.13 < z < 1.5, and a stellar mass range of 7.24 < log(M */M ⊙) < 9.73. We performed an X-ray study of a subset of these dwarf systems with Chandra and detected six new active galactic nuclei (AGN), increasing the number of known dwarf–dwarf-merger-related AGN from one to seven. We then compared the frequency of these AGN in grouped/paired dwarfs to that of isolated dwarfs and found a statistically significant enhancement (4σ–6σ) in the interacting sample. This study, the first of its kind at the lowest mass scales, implies that the presence of a nearby dwarf neighbor is efficient in triggering black hole accretion. These results open new avenues for indirect studies of the emergence of the first supermassive black holes.

Tracking Supermassive Black Hole Mergers from kpc to sub-pc Scales with AXIS

We present an analysis showcasing how the Advanced X-ray Imaging Satellite (AXIS), a proposed NASA Probe-class mission, will significantly increase our understanding of supermassive black holes undergoing mergers—from kpc to sub-pc scales. In particular, the AXIS point spread function, field of view, and effective area are expected to result in (1) the detection of hundreds to thousands of new dual AGNs across the redshift range 0&lt;z&lt;5 and (2) blind searches for binary AGNs that are exhibiting merger signatures in their light curves and spectra. AXIS will detect some of the highest-redshift dual AGNs to date, over a large range of physical separations. The large sample of AGN pairs detected by AXIS (over a magnitude more than currently known) will result in the first X-ray study that quantifies the frequency of dual AGNs as a function of redshift up to z=4.