X-ray Studies Research Articles

The Study of Lung Ultrasound, Chest CT and Chest X-ray in Children with COVID-19 Hospitalized in Mofid Children's Hospital During a Six-Month Period

Background: Coronavirus disease (COVID-19) is caused by severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2). The primary diagnostic tool for pediatric COVID-19 patients is polymerase chain reaction (PCR). Chest imaging findings in pediatric COVID-19 cases are often normal or mild. The correlation of lung ultrasound (LUS) with chest computed tomography (CT) and chest X-ray (CXR) in pediatric COVID-19 patients has not been extensively studied. Objectives: This study aimed to assess the correlation of LUS with chest CT and CXR in detecting COVID-19 pneumonia in children. Methods: This single-center cross-sectional study included patients under 18 years of age diagnosed with COVID-19 by PCR or by abnormal chest CT findings suggestive of COVID-19, admitted to Mofid Pediatric Hospital between December 2021 and August 2022. All patients underwent LUS. Approximately half of the patients also had a chest CT, and CXR was performed on 35 patients. Lung ultrasound and CT scores were calculated, and the correlation between these scores was evaluated. The correlation between LUS and CXR was also analyzed. Results: Sixty patients were included, of whom 21 were female, with a mean age of 4.9 ± 4.0 years. A significant correlation was observed between LUS and CT scores (correlation coefficient = 0.467, P = 0.011). Lesion distribution was similar between LUS and CT. However, no significant correlation was found between LUS scores and CXR findings (P = 0.392). Sixteen out of 19 patients with normal CXRs had LUS scores ≤ 4. Notably, three patients with normal CXRs had LUS scores of 8, 14, and 14. Conclusions: Lung ultrasound was more sensitive than CXR and demonstrated a significant correlation with CT. Lung ultrasound may serve as a safe alternative to CT for detecting COVID-19 pneumonia in pediatric patients.

Unveiling the shape: A multi-wavelength analysis of the galaxy clusters Abell 76 and Abell 1307

We analyse the dynamical state of the galaxy clusters Abell 76 and Abell 1307 from the optical point of view, presenting a coherent scenario that responds to the X-ray emissions observed in these structures. Our study is based on 231 and 164 spectroscopic redshifts, for the clusters A76 and A1307, respectively, obtained mostly with the Telescopio Nazionale Galileo, and complemented with others collected from the SDSS DR16 spectroscopic database and the literature. We find that A76 and A1307 are two galaxy clusters at z = 0.0390 and 0.0815, respectively, with a velocity dispersion of 650 ± 56 km s−1 and 863 ± 85 km s−1, and they show velocity distributions following, in practice, Gaussian profiles. From our dynamical analysis, X-ray studies and SZ-Planck emission, we obtain a mean total mass M500 = 1.7 ± 0.6 ⋅ 1014 M⊙ and 3.5 ± 1.3 ⋅ 1014 M⊙ for A76 and A1307, respectively. Using the SDSS DR16 photometric database, we find that the spatial distribution of likely cluster members in the case of A76 is very anisotropic, while A1307 shows a compact distribution of galaxies, but it is double peaked and elongated in the south-north direction. Using XMM-Newton X-ray data, we compared the surface brightness maps with galaxy distributions and noticed that both distributions are correlated. We reconstructed the total mass profile and velocity anisotropy of both clusters by analysing the full projected phase space, through the MG-MAMPOSSt code. Our study reveals a slight indication of radial orbits for A76, while A1307 seems to prefer more isotropic orbits in the whole cluster range. In summary, A76 represents a typical young cluster, in an early stage of formation, with a very low X-ray surface brightness but a high temperature showing a very anisotropic galaxy distribution. A1307 is however more consolidated and massive showing in-homogeneous galaxy distribution and an asymmetric X-ray emission, which suggest a scenario characterised by recent minor mergers.

Revealing the Role of Electronic Effect to Modulate the Photophysics and Z-Scan Responses of o-Locked GFP Chromophores.

Three novel core green fluorescent protein (GFP) chromophore analogues, based on a doubly locked conformation and variable electronic effects by replacing one hydrogen with bromine, iodine, and methyl, respectively, have been synthesized to modulate the push-pull effect. These chromophores exhibited intramolecular H-bonding, as evidenced by single-crystal X-ray and 1H NMR studies. The fluorescence quantum yields (ϕf) of all of the chromophores were found to be more than an order of magnitude higher (∼0.2) than the unlocked chromophores (∼0.01). It was found that the electronic effect did affect the nonradiative rates, as the quantum yields were found to vary with respect to different analogues in the same solvents. The effect of the push-pull effect was also evident by a higher Stokes-shifted emission in the case of the methyl derivative with respect to the bromo- and iodo-analogues. Furthermore, the emission spectra of these GFP chromophores were found to show positive solvatochromism, which was supported by a quantum chemical calculation. A detailed study, correlating the observed spectral changes with various solvent functions and supported by computational results, established a facile proton transfer, followed by twisted intramolecular charge transfer (TICT) to be the major nonradiative channels of these chromophores. Besides, a completely novel usage of these chromophores was explored for the first time by studying their third-order nonlinear optical characteristics in DMSO using a single-beam Z-scan technique. All of the chromophores exhibited tunable nonlinear refraction (NLR) and nonlinear absorption (NLA) properties that depend upon different substituent groups present in the chromophores. Here, the NLR was due to the effect of self-defocusing, whereas the NLA was triggered by reverse saturable absorption, which is attributed to the two-photon absorption (TPA) process. Surprisingly, the efficiency of the TPA ability of the chromophores was found to be a function of the induced electronic effect. Hence, this work opens a new route for the utility of the ortho-locked GFP chromophores in the field of nonlinear optical applications.

Syntheses of Tungsten Imido Cyclohexylidene Complexes Using Perfluoro-t-Butanol or Hexafluoro-t-Butanol as Acids.

The fluorinated alcohols, (CF3)3COH (RF9OH) and (CF3)2MeCOH (RF6OH), react with W(NR)2Cy2 (Cy=Cyclohexyl; R=2,6-diisopropylphenyl or 1-adamantyl) in C6D6 at 55 °C to give cyclohexylidene complexes. Traditional routes to terminal alkylidene complexes (neopentylidene or neophylidene) have used either triflic acid or HCl (rarely), but relatively weak fluorinated acids are sufficient and active bisalkoxide catalysts are therefore prepared directly. An α hydrogen abstraction reaction to give a cyclohexylidene complex from a biscyclohexyl complex appears to be as facile as α hydrogen abstraction to give a neopentylidene or neophylidene ligand, but isomerization of a cyclohexene formed through β hydrogen abstraction is also a possibility. The ORF9 ligands can be replaced readily with dimethylpyrrolide (Me2Pyr) or other more basic alkoxides. Single crystal X-ray studies were carried out on W(NAr)2Cy2, W(NAr)(ORF9)2(C6H10)(ArNH2), W(NAr)(ORF6)2(C6H10)(ArNH2), W(NAd)(ORF9)2(C6H10)(AdNH2), W(NAr)(O-i-PrF6)3Cy, and W(NAd)(η1-Me2Pyr)2(C6H10) (C6H10=cyclohexylidene).

Growth of L-asparagine monohydrate organic single crystals: An experimental and DFT computational approach for nonlinear optical applications

Good optical quality of L-asparagine monohydrate (C4H8N2O3.H2O) organic single crystal has been grown by adopting natural slow evaporation process at room temperature from aqueous solutions. The lattice parameters obtained by powder X-ray diffraction data revealed orthorhombic crystal system of the harvested crystal. The morphology and planes of the crystal have been identified. The molecular vibrations and functional groups have been specified by Fourier transform infrared (FTIR) spectroscopy studies. Energy dispersive X-ray (EDX) study has been availed to find out the elements constituting the crystal. Scanning electron microscopy, (SEM), provided the surface morphology of the crystal. The dependence of dielectric properties on frequency and temperature have been investigated and the electronic polarizability (α) has been determined. UV–vis spectral analysis shows that the crystal possesses good optical transmittance in the visible part of the energy spectrum. The optical band gap and the Urbach energy have been determined from lower absorption edge. Third order nonlinear susceptibility χ(3), nonlinear refractive index (n2), and linear susceptibility χ(1) have been calculated by Miller's generalized rule. The first-principle computation of band structure of electrons and the electron density of states have been discussed, which suggest that the crystals possess direct band gap. Density Functional Theory (DFT) with B3LYP function by Gaussian09W software was utilized to calculate HOMO-LUMO energy gap as well as non-linear optical parameters namely, linear polarizability (α), hyperpolarizability (β and γ) and dipole moment (μ) of L-asparagine monohydrate crystal. All the findings prove that L-asparagine monohydrate is a promising NLO crystal.

Microscopic Structure of Neat Linear Alkylamine Liquids: An X-Ray Scattering and Computer Simulation Study.

Linear amines, from propylamine to nonylamine, are studied under ambient conditions by X-ray scattering and molecular dynamics simulations of various force field models. The major finding is that the prepeak in alkylamines is about 1 order of magnitude weaker than that in alkanols, hence suggesting much weaker hydrogen bonding-induced clustering of the amine groups than for the hydroxyl groups. Computer simulation studies reveal that the OPLS-UA model reproduces the prepeak, but with larger amplitudes, while the GROMOS-UA and CHARMM-AA force fields show almost no prepeak. Simulations of all models show the existence of hydrogen-bonded clusters, equally confirmed by the prominent prepeak of the structure factor between the nitrogen atoms. The hydrogen bond strength, as modeled by the Coulomb association in classical force field models, is about the same order of magnitude for both systems. Then, one may ask what is the origin of the weaker prepeak in alkylamines? Simulation data reveal that the existence of the prepeak is controlled through the cancellation of the positive contributions from the charged group correlations by the negative contributions from the cross charged-uncharged correlations. The C2v symmetry of the amine headgroup hinders clustering, which favors cross correlations with the tail atoms. This is opposite to alkanols where the symmetry of the hydroxyl headgroup favors clustering and hinders cross correlations with the alkyl tail. This competition between charged and uncharged atomic groups appears as a general mechanism to explain the existence of scattering prepeaks, including their position and amplitude.

Spatio-spectral-temporal modelling of two young pulsar wind nebulae

Abstract Recent observations of a few young pulsar wind nebulae (PWNe) have revealed their morphologies in some detail. Given the availability of spatio-spectral-temporal data, we use our multi-zone (1D) leptonic emission code to model the PWNe associated with G29.7−0.3 (Kes 75) and G21.5−0.9 (G21.5) and obtain (by-eye) constraints on additional model parameters compared to spectral-only modelling. Kes 75 is a Galactic composite supernova remnant (SNR) with an embedded pulsar, PSR J1846−0258. X-ray studies reveal rapid expansion of Kes 75 over the past two decades. PWN G21.5 is also a composite SNR, powered by PSR J1833−1034. For Kes 75, we study a sudden plasma bulk speed increase that may be due to the magnetar-like outbursts of the central pulsar. An increase of a few percent in this speed does not result in any significant change in the model outputs. For G21.5, we investigate different diffusion coefficients and pulsar spin-down braking indices. We can reproduce the broadband spectra and X-ray surface brightness profiles for both PWNe, and the expansion rate, flux over different epochs, and X-ray photon index vs epoch and central radius for Kes 75 quite well. The latter three features are also investigated for G21.5. Despite obtaining reasonable fits overall, some discrepancies remain, pointing to further model revision. We find similar values to overlapping parameters between our 1D code and those of an independent 0D dynamical code (tide). Future work will incorporate spatial data from various energy wavebands to improve model constraints.

Multi-epoch jet outbursts in Abell 496: Synchrotron ageing and buoyant X-ray cavities draped by warm gas filaments

The galaxy cluster Abell 496 has been extensively studied in the past for the clear sloshing motion of its hot intracluster medium (ICM) on large scales, but the interplay between the central radio galaxy and the surrounding cluster atmosphere is mostly unexplored. We present a dedicated radio, X-ray, and optical study of Abell 496 with the aim being to investigate this connection. We use deep radio images obtained with the Giant Metrewave Radio Telescope (GMRT) at 150, 330, and 617 MHz, the Very Large Array (VLA) at 1.4 and 4.8 GHz, and the VLA Low Band Ionosphere and Transient Experiment (VLITE) at 340 MHz, with angular resolutions ranging from $0.^ prime 5$ to $25^ prime $. Additionally, we use archival Chandra and Very Large Telescope (VLT) MUSE observations. The radio images reveal three distinct periods of jet activity: an ongoing episode on subkiloparsec scales with an inverted radio spectrum; an older episode that produced lobes on scales of $ kpc, which now have a steep spectral index ($ and an black even older episode that produced lobes on scales of $ kpc with an ultrasteep spectrum ($ Archival Chandra X-ray observations show that the older and oldest episodes excavated two generations of cavities in the hot gas of the cluster. The outermost X-ray cavity has a clear mushroom-head shape, likely caused by its buoyant rise in the cluster's potential. Cooling of the hot gas is ongoing in the innermost 20 kpc, where warm, Halpha -bright filaments are visible in VLT-MUSE data. The Halpha -filaments are stretched toward the mushroom-head cavity, which may have stimulated ICM cooling in its wake. We conclude by discussing our nondetection of a radio mini-halo in this vigorously sloshing but low-mass galaxy cluster.

FEATURES OF ANTIBACTERIAL AND LYMPHOTROPIC THERAPY IN PATIENTS WITH PLEURAL EMPYEMA

Abstract. Acute empyema belongs to the category of severe surgical pathology. The difficulty of its treatment is caused by a number of objective and subjective reasons, in particular such as wide spread of antibiotic-resistant microflora and population allergy. Carefully collected analysis, patient’s examination, study of lungs function indicators, data of laboratory and X-ray studies, performing of serological, immunological and allergic tests do not always allow to identify the cause of acute empyema and are often not sufficient to identify its etiology. In spite of a great number of proposed methods of acute pleural empyema treatment, study of long-term results of all types of treatment shows that they do not guarantee 100% success. The outlined data indicates the necessity of improvement of etiotropic therapy in patients with pleural empyema. Constant search for new effective methods of treatment of the aimed pathology proves the relevance of the theme. The data outlined in this article indicates the necessity of improvement of etiotropic therapy in patients with pleural empyema.

Synthesis, crystal structure, Hirshfeld surface analysis, DFT computations and protein binding efficiency of a 1-D Ni(II) chain derived from a tridentate Schiff base ligand

A new Ni(II)-azido 1-D coordination polymer, [Ni2L2(μ1,1-N3)(μ1,3-N3)]n, was obtained through reaction of 1-[(3-dimethylamino-propylimino)-methyl]-naphthalen-2-ol (HL) and the perchlorate salt of nickel(II) in the presence of pseudohalide azide. X-ray crystallography and spectroscopic experiments (IR and UV-Vis) were used to describe this coordination polymer (CP). Single crystal X-ray studies revealed that the CP is a one-dimensional chain of Ni(II) in which the neighboring dimeric units (triply bridged by di-μ2-phenoxidoand µ1,1-N3) are further connected by μ1,3-azido bridges in a zig-zag fashion. The cooperative participation of N···H hydrogen bonding, π···π stacking and C-H···π interactions occur during crystal packing. A 2-D supramolecular architecture with star-shaped voids results from additional C–H···π stacking interactions. Hirshfeld surface analysis was used to look at the intermolecular interactions. DFT studies were carried out to calculate the HOMO-LUMO band gap of the ligand as well as the coordination polymer. Interaction of the CP with bovine serum albumin (BSA) protein was investigated spectroscopically by absorption and fluorescence titration methods. The result showed that the CP could quench the intrinsic fluorescence of BSA. Fluorescence resonance energy transfer (FRET) studies revealed that energy transfer takes place from BSA to the CP. Cyclic voltammetry of the CP indicated an irreversible cathodic redox couple assigned to Ni(II)/Ni(I).

Development of Novel Biocomposites with Antimicrobial-Activity-Based Magnesium-Doped Hydroxyapatite with Amoxicillin.

Background/Objectives: A biocomposite based on magnesium-doped hydroxyapatite and enriched with amoxicillin (MgHApOx) was synthesized using the coprecipitation method and is presented here for the first time. Methods: The stability of MgHAp and MgHApOx suspensions was evaluated by ultrasound measurements. The structure of the synthesized MgHAp and MgHApOx was examined with X-ray diffraction (XRD), Fourier transform infrared (FT-IR) spectroscopy and X-ray photoelectron spectroscopy (XPS). The crystalline structure was determined by X-ray diffraction. The FTIR data were collected in the range of 4000-400 cm-1. The morphology of the nanoparticles was evaluated by scanning electron microscopy (SEM). Furthermore, the biocompatible properties of MgHAp, MgHApOx and amoxicillin (Ox) suspensions were assessed using human fetal osteoblastic cells (hFOB 1.19 cell line). The antimicrobial properties of the MgHAp, MgHApOx and Ox suspension nanoparticles were assessed using the standard reference microbial strains Staphylococcus aureus ATCC 25923, Escherichia coli ATCC 25922 and Candida albicans ATCC 10231. Results: X-ray studies have shown that the biocomposite retains the characteristics of HAp and amoxicillin. The SEM assessment exhibited that the apatite contains particles at nanometric scale with acicular flakes morphology. The XRD and SEM results exhibited crystalline nanoparticles. The average crystallite size calculated from XRD analysis increased from 15.31 nm for MgHAp to 17.79 nm in the case of the MgHApOx sample. The energy-dispersive X-ray spectroscopy (EDS) and X-ray photoelectron spectroscopy (XPS) analysis highlighted the presence of the constituent elements of MgHAp and amoxicillin. Moreover, XPS confirmed the substitution of Ca2+ ions with Mg2+ and the presence of amoxicillin constituents in the MgHAp lattice. The results of the in vitro antimicrobial assay demonstrated that MgHAp, MgHApOx and Ox suspensions exhibited good antimicrobial activity against the tested microbial strains. The results showed that the antimicrobial activity of the samples was influenced by the presence of the antibiotic and also by the incubation time. Conclusions: The findings from the biological assays indicate that MgHAp and MgHApOx are promising candidates for the development of new biocompatible and antimicrobial agents for biomedical applications.

1,4-Naphthoquinone thiazoles: Synthesis, crystal structure, anti-proliferative activity, and inverse molecular docking study

In this study, 1,4-naphthoquinone thiazole hybrids were synthesized by reacting 1,4-naphthoquinone thioureas with various α-bromoketones in 78–86 % yields and characterized using 1H NMR, 13C NMR, FT-IR, and HRMS techniques. Furthermore, single crystal x-ray diffraction studies were also performed for 3b and 3c hybrids to determine stereochemistry. Density Functional Theory (DFT) calculations were performed to obtain additional information and to support the x-ray studies. The in vitro anti-proliferative activities of 1,4-naphthoquinone thiazoles were investigated against PC3 human prostate cancer cells. The products 3a–h showed anti-proliferative activity against PC3 cells, and the cell viability studies showed that the IC50 values of compounds 3f and 3e were 20.10 µM and 21.14 µM, respectively, while the other compounds exhibited lesser cytotoxic effects than the former two. Potential target underlying the mechanism of action of the synthesized compounds against prostate cancer was identified using inverse (reverse) docking method. Molecular dynamics simulation was also conducted to confirm the stability of the 3f/enzyme system. It was determined that the solubility in ethanol was better for compounds bearing methyl substituent on X1 location than compounds containing tert‑butyl on the same location. Compounds with F atom on X2 position were more soluble than the others in the corresponding groups.

Synthesis, single crystal study, molecular docking, and in vitro anticancer screening of a series of isoxazolone derivatives of chlorovinyl benzalaldehydes

A series of isoxazole derivatives (2a-i) were synthesized by conventional method using various substituted chlorovinyl benzaldehydes as precursors. Structures of all the synthesized compounds were confirmed by spectroscopic data (1H NMR, FTIR, HRMS). Single crystal X-ray study of four compounds was carried out. Molecular docking study was performed and the compounds were screened for in vitro anticancer activity. The results show that compounds with no substituent or smaller substituents on benzene ring have significant antiproliferative activity against tested cell line i.e. MCF7.

Optical and X-ray studies of the Be/X-ray binary IGR J06074+2205

ABSTRACT We present the results obtained from X-ray and optical analysis of the Be/X-ray binary IGR J06074+2205, focusing on before, during, and after the X-ray outbursts in 2023 October and December. The properties of the neutron star in the binary are investigated using NICER and NuSTAR observations during the X-ray outbursts. The pulse profiles across a broad energy range, are found to be strongly dependent on luminosity and energy, revealing the complex nature of the emitting region. An absorbed power law can describe each NICER spectrum in the 1–7 keV band. The 3–79 keV NuSTAR spectrum can be well described by a negative and positive power law with an exponential cut-off model. Utilizing the MAXI/GSC long-term light curve, we estimate the probable orbital period to be 80 or 80/n (n = 2, 3, 4) d. We investigate the evolution of the circumstellar disc around the Be star by using optical spectroscopic observations of the system between 2022 and 2024. We observe variable H $\alpha$ and Fe ii emission lines with an increase in equivalent width, indicating the presence of a dynamic circumstellar disc. A distinct variation in the V/R value for H $\alpha$ and Fe ii lines is also observed. The appearance of additional emission lines, such as He i (5875.72 Å), He i (6678 Å), and He i (7065 Å), during the post-outburst observation in 2024 February suggests the growing of a larger or denser circumstellar disc. The disc continues to grow without any noticeable mass-loss, even during the 2023 X-ray outbursts, which may lead to a future giant X-ray outburst.

Heteronuclear cadmium(II)/cobalt(III) cyanide coordination polymers with 1-methylimidazole and 1-ethylimidazole ligands: synthesis, characterization and catalytic activities

Two new heteronuclear Cd(II)/Co(III) compounds, {[Cd(1-meim)3Cd0.5(1-meim)Co(μ-CN)4(CN)2]}n (1) and {[Cd(1-etim)3Cd0.5(1-etim)2Co(μ-CN)3(CN)3]⋅H2O}n (2) (1-meim: 1-methylimidazole, 1-etim = 1-ethylimidazole), have been synthesized and characterized using elemental analysis, FT-IR and Raman spectroscopy, single-crystal X-ray diffraction techniques. The single crystal X-ray study shows that the compound 1 exhibited a 1D double chain structure and is further linked into 3D supramolecular architectures through CH⋅⋅⋅N and π⋅⋅⋅π interactions. Whereas the compound 2 displayed 2D network which is extended into a 3D supramolecular framework by OH⋅⋅⋅N hydrogen bonds and CH∙∙∙π interactions. In 1 and 2, each Co(III) ion is coordinated by six carbon atoms from cyanide ligands, thus showing an octahedral coordination geometry. Cd1 and Cd2 ions exhibited two different geometries, distorted trigonal bipyramidal and octahedral. Furthermore, phase purities, catalytic and thermal properties were investigated.

Variations of the elemental composition distribution over the thickness of YBa2Cu3O7-δ thin films obtained by pulsed laser deposition from one target

Epitaxial YBa2Cu3O7‒δ (YBCO) films 150-200 and 300 nm thick, respectively, were deposited on SrTiO3 (100) substrates by pulsed laser deposition at different conditions: with and without using the velocity filtration technique. The films have T(R=0) in the range of 77.4 - 87 R(T) depending on the conditions of deposition from one target with YBa2Cu3O6.8 composition. The films contain Zn, Sr, Pd, Ag and Ti impurity elements obtained from the target (a total of no more than 2 at. % ). Data of the film resistance temperature dependences, X-ray phase analysis, analysis of X-ray fluorescence (XRF) spectra and study of the surface relief by SEM methods revealed the nonuniform distributions of impurity and matrix Y, Ba, Cu elements over the film depth. Impurity concentrations near the surface lead to the formation of faceted spiral pyramids on the surface, which probably evolve into large elongated particles according to the Ostwald mechanism. This knowledge is practically important for optimizing pulsed laser deposition technologies and creating 2D instruments and devices for studying physical phenomena.

The Remarkable X-Ray Spectra and Variability of the Ultraluminous Weak-line Quasar SDSS J1521+5202

We present a focused X-ray and multiwavelength study of the ultraluminous weak-line quasar (WLQ) SDSS J1521+5202, one of the few X-ray weak WLQs that is amenable to basic X-ray spectral and variability investigations. J1521+5202 shows striking X-ray variability during 2006–2023, by up to a factor of ≈32 in 0.5–2 keV flux, and our new 2023 Chandra observation caught it in its brightest X-ray flux state to date. Concurrent infrared/optical observations show only mild variability. The 2023 Chandra spectrum can be acceptably described by a power law with intrinsic X-ray absorption, and it reveals a nominal intrinsic level of X-ray emission relative to its optical/ultraviolet emission. In contrast, an earlier Chandra spectrum from 2013 shows apparent spectral complexity that is not well fit by a variety of models, including ionized absorption or standard Compton-reflection models. Overall, the observations are consistent with the thick-disk plus outflow model previously advanced for WLQs, where a nominal level of underlying X-ray emission plus variable absorption leads to the remarkable observed X-ray variability. In the case of J1521+5202, it appears likely that the outflow, and not the thick disk itself, lies along our line of sight and causes the X-ray absorption.

Luminescent yttrium organic frameworks: Cell imaging, gas adsorption and nitro sensing applications

The flexibility of ligand (L) yield, two different yttrium organic frameworks, denoted as {[Y(L)2(H2O)4]·Cl3·DMF·(H2O)3·(S)}n (MOF-1) and {[Y(L)3/2(H2O)2]·(NO3)3·(S)}n (MOF-2), where L denotes 9,10-bis((4-carboxylatopyridinium-1-methylene)anthracene and S denotes the disordered solvent molecules. Detailed single crystal X-ray study established a one dimensional (1D) chain for MOF-1 and a three dimensional (3D) frameworks with one channel voids structure for MOF-2, respectively, due to different conformation of the ligand. In both MOFs, Y(III) have bicapped trigonal prismatic geometry. The phase purity of both MOFs has been confirmed by powder X-ray diffraction (PXRD), thermogravimetric analysis (TGA) and IR spectroscopic studies. MOF-1, with its particle size in nano range, good fluorescence property and solubility in water, is a suitable candidate for cell imaging study. In contrast, three dimensional framework of MOF-2, with small voids, makes it well suited for gas adsorption and sensing of nitro aromatics compounds.

Characterization of the Western Pictor A Hotspot in Hard X-Rays with NuSTAR

The origin of X-ray emission from the resolved kiloparsec-scale jets and hotspots of many active galactic nuclei remains uncertain, particularly where the X-ray emission is separate from the radio-optical synchrotron component. Possible explanations include synchrotron emission from a second electron population and external Compton or synchrotron self-Compton processes—alternatives which imply very different physical conditions within the jet. Until recently, X-ray studies of resolved jets and hotspots have been restricted to below ∼10 keV, often showing a hard spectral index indicating a spectral peak beyond this energy range. Here we present NuSTAR observations of the nearby powerful radio galaxy Pictor A, in which we clearly detect the western hotspot at approximately 4′ from the host galaxy, the most significant detection of hotspot emission above 10 keV to date. The NuSTAR spectrum is best fit by a single power law of index Γ = 2.03 ± 0.04; an exponential cutoff gives a 1σ lower limit on the cutoff energy of 40.7 keV. We confirm previous findings of variations in the soft X-ray flux detected by Chandra over the 2000 to 2015 period, at a significance of 6.5σ. This rises to >8σ in the common 3–8 keV band using the combined 22 yr span of Chandra and NuSTAR observations. The variability of the western Pictor A hotspot strongly confirms the previously argued synchrotron nature of the X-ray emission for the hotspot, while the lower bound to the spectral cutoff energy implies electron energies in the hotspot reach up to at least a few TeV.

Exploring the binding mode of phenyl and vinyl boronic acids to human carbonic anhydrases

Boronic acids are an interesting but still poorly studied class of carbonic anhydrase inhibitors. Previous investigations proved that derivatives incorporating aromatic, arylalkyl, and arylalkenyl moieties are low micromolar to millimolar inhibitors for several α- and β-CAs involved in pathologic states.Here we report a high-resolution X-ray study on two classes of boronic acids (phenyl and vinyl) in complex with hCA II. Our results unambiguously clarify the binding mode of these molecules to the human carbonic anhydrase active site, which occurs through their tetrahedral anionic form, regardless of the nature of the organic scaffold. Data here presented contribute to the understanding of the inhibition mechanism of boronic acids that can be fruitfully used for the rational design of novel and effective isozyme-specific carbonic anhydrase inhibitors.