Publications by authors named "Ravikumar P"

For biomedical applications, material scientists all over the world are working to develop cost-effective technologies and thereby synthesize new nanocomposite materials that are biocompatible, bioactive, scalable and naturally abundant. This study focuses on synthesizing and evaluating nanocomposites of zinc oxide (ZnO) and chitosan (CS) derived from crab shells, in three different weight proportions (1:0.5, 1:1, and 1:2).

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A Ni-catalyzed C-N bond activation of 2-pyridylpyridone and 1-(9-alkyl 9-purin-6-yl)pyridin-2(1)-one and coupling with arylboronic acid have been achieved. A unique feature of this reaction is the strategic activation of the bridging C-N bond and replacement of the pyridone unit with aryl groups using nickel catalyzed Suzuki-Miyaura coupling. This provides an exciting new tool to build C-C bonds in the place of pyridones.

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Introduction Primary aldosteronism (PA), once considered rare, is now recognized as the most common cause of secondary hypertension, accounting for almost a quarter of resistant hypertension (RH) cases. Despite this, PA remains underdiagnosed, with an extremely low percentage of RH patients undergoing screening. Methods In a specialty diabetes-endocrinology clinic, the aldosterone:renin ratio (ARR) was assessed in 115 consecutive RH patients (ages 21-93 years; 47% male; 87% with type 2 diabetes).

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The presented research introduces the "Cells-on-Particles" integrated aerosol sampling and cytotoxicity testing in vitro platform, which allows for the direct assessment of the biological effects of captured aerosol particles on a selected cell type without the need for extraction or resuspension steps. By utilizing particles with unaltered chemical and physical properties, the method enables simple and fast screening of biological effects on specific cell types, making it a promising tool for assessing the cytotoxicity of particulate matter in ambient and occupational air. Platforms fabricated from cellulose acetate (CA) and poly[ε]caprolactone (PCL) were proven to be biocompatible and promoted the attachment and growth of the human bronchial epithelial cell line BEAS-2B.

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Composite materials have become prominent in the aerospace, automotive, wind energy, biomedical, and machine tool industries. This has demanded the evaluation of the dynamic mechanical and tribological behaviour of composites to understand their performance and ensure their reliability and safety in varied operating conditions. In this study, the effect of halloysite nano-clay addition on the dynamic mechanical and tribological properties of the carbon/glass hybrid composites was investigated.

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The regio-/stereoselective synthesis of vinyl cyclobutanols from alkynyl cyclobutanols is demonstrated. Here, selective C-C bond activation of the cyclopropyl alcohol ring has been achieved in the presence of the cyclobutanol ring. The KIE experiments indicated the noninvolvement of the O-H oxidative addition step in the rate-determining step.

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In this work, we have developed an efficient method for the intramolecular double hydroamination of aniline by employing -amino 1,6-diyne as a potential starting material. This protocol enables easy access to bioactive motif 3,4-dihydro-1-[1,4]oxazino[4,3-]indole through an intramolecular cascade bicyclization and concomitant isomerization pathway in one pot. This transformation has been effectively achieved by utilizing a stereoelectronically tuned, π-accepting NHC-supported copper(I) system.

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Selective functionalization of the indole-C3-C bond with aromatic/heteroaromatic 1,2-diketones has been uncovered for the first time. Cobalt catalyst was found to be an effective catalyst for this unusual transformation. This -C-C bond functionalization occurred in the presence of easily available weakly coordinating groups such as ketone and ester.

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Introduction: Alopecia areata (AA) is a non-scarring alopecia of chronic autoimmune etiology with heterogenous severity against the anagen hair follicle over the scalp, beard, or any part of the body and is associated with a significant psychological morbidity in the mental status of the patients leading the patients to seek treatment for cosmetic reasons. The management of AA is very unpredictable and is associated with various cosmetic adverse effects. This study aimed at comparing the efficacy and safety of a novel procedure of laser-assisted drug delivery system of steroids with the first-line procedure of intralesional steroids (ILS) for the treatment of patchy AA.

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Herein, we report the facile synthesis of indole C(4)-acrylophenone using a C-H bond activation strategy. For this conversion, an unsymmetrical alkyne (phenylethynyl ether) in the presence of cobalt(III)-catalyst works efficiently. In this process, alkyne gets oxidized in the presence of generated water, which is the key step for this method, for which trifluoroethanol is the water source.

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Purpose: To evaluate the impact of special software training in computer and smartphone apps as a form of rehabilitation to improve the quality of life of individuals with visual impairment (VI).

Methods: The study utilized a one-group pretest-posttest design. A total of 50 individuals aged 15 years and older with VI participated in the training, which included special software (NVDA) and mobile app training for 60 hours at the Visual Rehabilitation Center.

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Chimeric antigen receptor (CAR) T cell therapy targeting CD19 has achieved tremendous success treating B cell malignancies; however, some patients fail to respond due to poor autologous T cell fitness. To improve response rates, we investigated whether disruption of the co-inhibitory receptors CTLA4 or PD-1 could restore CART function. CRISPR-Cas9-mediated deletion of CTLA4 in preclinical models of leukemia and myeloma improved CAR T cell proliferation and anti-tumor efficacy.

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Herein, we have demonstrated a rhodium-catalyzed carboamination of olefin with the double bond intact. For the first time, deacylative carboamination of the maleimide has been achieved wherein phenoxyacetamide has behaved as the aminating source. In addition to carboamination, we have also disclosed the C-H olefination protocol where the maleimide group has been installed successfully in the -position of phenoxyacetamide.

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A rhodium-catalyzed oxidative C-H/N-H dehydrogenative [3 + 2] annulation strategy has been reported between anilines and -allylbenzimidazole for the synthesis of 2-methylindole scaffolds. An -allylbenzimidazole has been used as a 2C synthon for the synthesis of indole, and more importantly, this transformation involves the cleavage of the thermodynamically stable C-N bond of allylamine. Detailed mechanistic studies have been performed and a key intermediate was detected in HRMS.

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This review provides a broad overview of the recent developments in the field of transition metal-catalyzed C-H/C-C bond activation and coupling with 1,3-diyne for assembling alkynylated heterocycles, bis-heterocycles, and 1,3-enynes. Transition metal-catalyzed inert bond (C-H/C-C) activation has been the focus of attention among synthetic chemists in recent times. Enormous developments have taken place in C-H/C-C bond activation chemistry in the last two decades.

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Herein, we report the annulation of indole-2-carboxamides with bicycloalkenes, to synthesize β-carboline-1-one derivatives under mild conditions. The commercially available ruthenium catalyst was used for the reaction. This reaction tolerates a wide range of functional groups and affords a good yield of β-carboline-1-one derivatives.

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The sustainable C-H bond ethynylation of -aryl γ-lactam has been achieved in a highly regioselective manner. In this protocol, earth-abundant cobalt(III)-catalyst was found to be effective, triggering the C-H metalation using a weakly coordinating lactam group. Herein, the ortho-()-H ethynylation has been obtained regioselectively.

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Article Synopsis
  • A new Rh-catalyzed method for propenylating C(sp)-H bonds using -allyl benzimidazole has been successfully developed.
  • This is the first report of this transformation, showcasing a tandem process that involves C-H allylation followed by alkene isomerization for a highly selective -propenylated product.
  • Comprehensive mechanistic studies were carried out, characterizing intermediate rhodacycles to gain insights into the reaction mechanism.
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Diagnostic coding, or ICD coding, is the task of assigning diagnosis codes defined by the ICD (International Classification of Diseases) standard to patient visits based on clinical notes. The current process of manual ICD coding is time-consuming and often error-prone, which suggests the need for automatic ICD coding. However, despite the long history of automatic ICD coding, there have been no standardized frameworks for benchmarking ICD coding models.

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Alkynes occupy a prominent role as a coupling partner in the transition metal-catalysed directed C-H activation reactions. Due to low steric requirements and linear geometry, alkynes can effectively coordinate with metal d-orbitals. This makes alkynes one of the most successful coupling partners in terms of the number of useful transformations.

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A Ni-catalyzed C6 followed by C5 cascade C-H activation/[2 + 2 + 2] annulation of 2-pyridone with alkynes has been achieved. A change in the reaction pathway was achieved by tuning the reaction conditions and incorporating a directing group. A wide variety of substrates and alkynes are amenable to this transformation.

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We report here a Rh(III) catalyzed regio- and stereoselective synthesis of alkynylated and bis-isocoumarin from 1,3-dialkyne. Exclusive one-pot formation of 3,3-bis-isocoumarin isomers has been achieved by eliminating several other possibilities. This is the first example of transition metal catalyzed synthesis of alkynylated and bis-isocoumarin scaffolds.

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Synthetic receptor signalling has the potential to endow adoptively transferred T cells with new functions that overcome major barriers in the treatment of solid tumours, including the need for conditioning chemotherapy. Here we designed chimeric receptors that have an orthogonal IL-2 receptor extracellular domain (ECD) fused with the intracellular domain (ICD) of receptors for common γ-chain (γ) cytokines IL-4, IL-7, IL-9 and IL-21 such that the orthogonal IL-2 cytokine elicits the corresponding γ cytokine signal. Of these, T cells that signal through the chimeric orthogonal IL-2Rβ-ECD-IL-9R-ICD (o9R) are distinguished by the concomitant activation of STAT1, STAT3 and STAT5 and assume characteristics of stem cell memory and effector T cells.

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