240 research outputs found

    Microwave Assisted Expeditious and Green Cu(II)-Clay Catalyzed Domino One-Pot Three Component Synthesis of 2H-indazoles

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    A simple and efficient synthesis of 2H-indazoles is achieved from 2-primary amines, bromobenzaldehydes and sodium azide through domino condensation, C–N and N–N bond formations, catalyzed by a heterogeneous Cu(II)-Clay catalyst. The recyclable heterogeneous Cu(II)-Clay catalyst exhibited a remarkable activity for the title reaction without any additives. An assortment of structurally diverse 2H-indazoles were prepared in good to excellent yields from easily available starting materials by using this protocol. The Cu(II)-Clay catalyst was characterized by using X-Ray Diffraction (XRD), Scanning Electron Microscopy (SEM), and Brunauer-Emmett-Teller (BET) techniques. 

    Miocene phosphorites from the Murray Ridge, Northwestern Arabian Sea

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    Phosphorites from the Murray Ridge, NW Arabian Sea comprise nodules, bioclasts, and bone fragments. The nodules are made up of a homogeneous, light-colored phosphate nucleus consisting of Rivulariacean filamentous cyanobacteria and a thin dark-grey colored phosphate cortex showing abundant microbial filaments and microborings. The bioclasts comprise of ∼14-14.5 Ma old planktonic foraminifers, accepted as the time of deposition. Spherical to ovoid-shaped apatite microparticles resembling fossil bacteria are distinct components in the bioclasts. Bone fragments exhibit apatite fillings. The nodules and bone fragments consist entirely of carbonate fluorapatite (CFA) with low Al, K, and Th concentrations suggesting absence of continental detritus. Shale-normalized REE patterns of the samples support a seawater-derived composition. The highly uniform initial εNd values of -4.8 to -5.1 are interpreted as the seawater value at the onset of phosphatization ∼14 Ma ago. In contrast, 87Sr/86Sr ratios show a large range of 0.709055 to 0.709124 corresponding to unusually young stratigraphic ages of ∼1 to 3 Ma. The data are interpreted as evidence for post-depositional Sr exchange of the recrystallizing phosphorites with fluids isotopically not much different from modern seawater. It is concluded that the phosphorites formed under oxic, shallow-water conditions where microbial populations assimilated phosphorus primarily from seawater and mediated precipitation of CFA during early diagenesis at the sediment-water interface on different substrates

    Thermo-Kinetic Investigation of Comparative Ligand Effect on Cysteine Iron Redox Reaction

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    Transition metal ions in their free state bring unwanted biological oxidations generating oxidative stress. The ligand modulated redox potential can be indispensable in prevention of such oxidative stress by blocking the redundant bio-redox reactions. In this study we investigated the comparative ligand effect on the thermo-kinetic aspects of biologically important cysteine iron (III) redox reaction using spectrophotometric and potentiometric methods. The results were corroborated with the complexation effect on redox potential of iron(III)-iron(II) redox couple. The selected ligands were found to increase the rate of cysteine iron (III) redox reaction in proportion to their stability of iron (II) complex (EDTA < terpy < bipy < phen). A kinetic profile and the catalytic role of copper (II) ions by means of redox shuttle mechanism for the cysteine iron (III) redox reaction in presence of 1,10-phenanthroline (phen) ligand is also reported

    Rock magnetic and geochemical record in a sediment core from the Eastern Arabian Sea: diagenetic and environmental implications during the late Quaternary

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    Rock magnetic concentration, grain size and mineralogy parameters together with organic carbon, calcium carbonate, redox-sensitive elements, &#948;18O of Globigerinoides ruber and radiocarbon dating were carried out on a 445 cm long sediment core collected at 1380 m depth off Mangalore, southwestern margin of India. The top 290 cm sediments of the core correspond to the last 18 kaBP. The &#948;18O and magnetic records exhibit major events at &#8764; 16 kaBP, 14.5 kaBP, 11.5 kaBP and 9.8/8.6 kaBP related to start and intensity of the summer monsoon and climate change, and are synchronous with that of the western Arabian Sea and North Atlantic. The sediments with high magnetic susceptibility correlate with high sedimentation rates. The sediments are dominated by fine-grained magnetite, but intervals of 1.2-3.8 kaBP and 10-13.5 kaBP were subjected to diagenetic changes, resulting in the dissolution of fine-grained magnetites and enrichment of redox-sensitive trace elements (Cu, Ni, Zn, V, Mo and U). The sediments between 290 cm and 445 cm correspond to 18-27 kaBP and are characterized by distinct decrease in magnetic concentration, grain size and mineralogy parameters, high organic carbon, low concentrations of redox-sensitive trace elements and abundant pyritized tubules. The reductive diagenetic conditions indicated by rock magnetic properties are in contrast with the weak sub-oxic conditions revealed by low concentrations of trace elements in the sediments. The seasonal organic matter flux produced during the winter monsoon and moderate sedimentation rates favoured reductive diagenesis in the sediments at and below the last glacial maximum (LGM). Intermittent bioturbation, however, allowed oxidants to penetrate into the sediments, remobilized redox-sensitive trace elements into the water column and modified the primary geochemical signal of the sedimentary environment

    Dual-Energy Multidetector Computed Tomography: A Highly Accurate Non-Invasive Tool for in Vivo Determination of Chemical Composition of Renal Calculi

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    Introduction. Computed tomography is more accurate than excretory urography in evaluation of renal stones due to its high sensitivity and temporal resolution; it permits sub-millimetric evaluation of the size and site of calculi but cannot evaluate their chemical composition. Dual-energy computed tomography allows evaluating the chemical composition of urinary calculi using simultaneous image acquisition at two different energy levels. The objective of the research was to determine renal stone composition using dual-energy multidetector computed tomography, and its correlation with post-extraction chemical analysis of stones. Materials and Methods. This prospective study was conducted in the Department of Radiodiagnosis and Imaging from September 2017 to March 2019. A total of 50 patients with urolithiasis at the age of 18-70 years were included in the study. Dual-energy computed tomography ratios of various stones were noted, and preoperative composition of calculi was given based on their colour and dual-energy computed tomography ratio. These results were compared with the post-extraction chemical analysis of stones (using Fourier infrared transform spectroscopy as the standard comparative method.) Results. The most common type of calculi in our study population was calcium oxalate stones (78%) followed by uric acid stones (12%), cystine stones (6%) and hydroxyapatite stones (4%). The dual-energy ratio of calcium oxalate, uric acid, cystine and hydroxyapatite stones ranged from 1.38-1.59, 0.94-1.08, and 1.20-1.28 and 1.52-1.57, respectively, with the mean dual-energy ratio of 1.43, 1.01, 1.25 and 1.55, respectively. Dual-energy computed tomography was found to be 100% sensitive and specific for differentiating uric acid stones from non‑uric acid stones. The sensitivity and specificity in differentiating calcium oxalate calculus from non‑calcium oxalate calculus was 97.5% and 90.9%, respectively, with 96% accuracy and kappa value of 0.883 suggesting strong agreement. Conclusions. Dual-energy computed tomography is highly sensitive and accurate in distinguishing between various types of renal calculi. It has vital role in management as uric acid calculi are amenable to drug treatment, while most of non-uric acid calculi require surgical intervention

    Nonthermal acceleration radiation of atoms near a black hole in presence of dark energy

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    We investigate how dark energy affects atom-field interaction. To this end, we consider acceleration radiation of a freely falling atom close to a Schwarzschild black hole (BH) in the presence of dark energy characterized by a positive cosmological constant Λ\Lambda. The resulting spacetime is endowed with a BH and a cosmological (or de Sitter) horizon. Our consideration is a \textit{nonextremal} (1+1)(1+1)-dimensional geometry with horizons far apart, giving rise to a flat Minkowski-like region in between the two horizons. Assuming a scalar (spin0\text{spin}-0) field in a Boulware-like vacuum state, and by using a basic quantum optics approach, we numerically achieve excitation probabilities for the atom to detect a photon as it falls toward the BH horizon. It turns out that the nature of the emitted radiation deeply drives its origin from the magnitude of Λ\Lambda. In particular, radiation emission is enhanced due to dilation of the BH horizon by dark energy. Also, we report an oscillatory nonthermal spectrum in the presence of Λ\Lambda, and these oscillations, in a varying degree, also depend on BH mass and atomic excitation frequency. We conjecture that such a hoedown may be a natural consequence of a constrained motion due to the bifurcate Killing horizon of the given spacetime. The situation is akin to the Parikh-Wilzcek tunneling approach to Hawking radiation where the presence of extra contributions to the Boltzmann factor deforms the thermality of flux. It apparently hints at field satisfying a modified energy-momentum dispersion relation within classical regime of general relativity arising as an effective low energy consequence of an underlying quantum gravity theory. Our findings may signal new ways of conceiving the subtleties surrounding the physics of dark energy.Comment: 13 pages, 4 figure

    2-(3-Benzoyl-4-hy­droxy-1,1-dioxo-2H-1λ6,2-benzothia­zin-2-yl)-1-phenyl­ethanone

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    In the title mol­ecule, C23H17NO5S, the heterocyclic thia­zine ring adopts a half-chair conformation, with the S and N atoms displaced by 0.383 (3) and 0.473 (3) Å, respectively, on opposite sides of the mean plane formed by the ring C atoms. The phenyl rings attached to carbonyl groups lie almost parallel to each other at a dihedral angle 7.43 (9)°, the distance between the centroids of the rings being 3.780 (1) Å. The C(thia­zine)—C=O and O=C—CH2 groups make dihedral angles of 37.56 (16) and 1.93 (18)°, respectively, with the phenyl groups to which they are attached. The crystal structure features O—H⋯O and C—H⋯O hydrogen bonds and further consolidated by C—H⋯π inter­actions; an intra­molecular O—H⋯O hydrogen bond is also present

    Facial expression recognition using lightweight deep learning modeling

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    Facial expression is a type of communication and is useful in many areas of computer vision, including intelligent visual surveillance, human-robot interaction and human behavior analysis. A deep learning approach is presented to classify happy, sad, angry, fearful, contemptuous, surprised and disgusted expressions. Accurate detection and classification of human facial expression is a critical task in image processing due to the inconsistencies amid the complexity, including change in illumination, occlusion, noise and the over-fitting problem. A stacked sparse auto-encoder for facial expression recognition (SSAE-FER) is used for unsupervised pre-training and supervised fine-tuning. SSAE-FER automatically extracts features from input images, and the softmax classifier is used to classify the expressions. Our method achieved an accuracy of 92.50% on the JAFFE dataset and 99.30% on the CK+ dataset. SSAE-FER performs well compared to the other comparative methods in the same domain

    INDEXED STROKE VOLUME IN CHILDREN WITH VARYING LEFT VENTRICLE EJECTION FRACTION AND ITS CORRELATION WITH VARIOUS CARDIAC FACTORS

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    OBJECTIVE: To determine the variation in indexed stroke volume (LVSVi) in children with varying left ventricle ejection fraction (LVEF) using cardiac magnetic imaging (CMR) and its correlation with various cardiac factors. METHODS: This observational comparative study was conducted at The Children’s Hospital, Lahore, Pakistan from December 2018 to November 2021. All children below 18 years’ age presenting to hospital for CMR for tissue characterization, having normal vital organs function and no clinical signs of heart failure were included in the study. Relevant clinical data was recorded. CMR was performed using 1.5T Philips Ingenia MRI scanner. The data were analyzed with varying LVEF and correlation of LVSVi with various cardiac factors including indexed left ventricular end diastolic volume (LVEDVi), cardiac output (CO) and heart rate (HR). RESULTS: Out of 175 patients, 170 children up to 18 years old completed the test with mean age 14.3±3.3 years. Mean LVSVi was 42+12 ml/m2 which followed Frank Starling curve except in children with LVEF <36%. Mean LVEDVi was 86±34 ml/m2. LVSVi did not correlate with heart rate or indexed ventricular systolic volumes acting as an independent variable. Minimum LVSVi remained similar all groups as demonstrated through centile distribution. CONCLUSION: Indexed stroke volume is an independent variable in children having normal vital organs function with varying LVEF. It can serve as an independent monitoring parameter for clinical management of children with impaired ejection fraction

    N-Butyl-4-hydr­oxy-2-methyl-2H-1,2-benzothia­zine-3-carboxamide 1,1-dioxide

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    The title compound, C14H18N2O4S, contains hydrogen-bonded dimeric pairs of mol­ecules arranged around inversion centers, forming 14-membered rings with an R 2 2(14) motif. The structure is stabilized by extensive intra­molecular inter­actions. The thia­zine ring adopts a half-chair conformation, with the S and N atoms displaced by −0.485 (3) and 0.296 (3) Å, respectively, from the plane formed by the remaining atoms of the ring
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