Publications by authors named "Subir Paul"

Nature uses complex self-assembly pathways to access distinct functional non-equilibrium self-assemblies. This remarkable ability to steer same set of biomolecules into different self-assembly states is done by avoiding thermodynamic pit. In synthetic systems, on demand control over 'Pathway Complexity' to access self-assemblies different from equilibrium structures remains challenging.

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Metal-free catalysts for various organic transformations are of high demand now. In this study, we present a new carbon dot as an efficient metal-free nanophotocatalyst for carrying out a series of organic bond formation reactions. Using a single photocatalyst carbon dot, Csp-Csp, Csp-B, Csp-S, Csp-Se, and C-P bond formation reactions were performed with a high yield of the corresponding products.

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Perovskite nanocrystals (PeNCs) synthesized by colloidal solution methods are an outstanding case of study due to their remarkable optical features, different from their bulk counterpart, such as a tuneable band gap and narrower photoluminescence emission, altered by the size and shape. However, the stability of these systems needs to be improved to consolidate their application in optoelectronic devices. Improved PeNC quality is associated with a less defective structure, as it affects negatively the photoluminescence quantum yield (PLQY), due to the essential, but at the same time labile interaction between the colloidal capping ligands and the perovskite core.

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Surface modification of carbon dots covalent conjugation with a dipeptide resulted in a dramatic change in the fluorescence emission from green to red. The hydrophobic peptide units linked to the surface of the modified carbon dots helped them to aggregate by generating a nanodot-fabricated nanofibrous network. This nanofibrous network showed excellent electrical conductivity and photo-switching behavior, better than those of the non-aggregated dots.

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With the increasing number of COVID-19-associated nephropathy (COVAN), biopsy-proven cases of collapsing variety of focal segmental glomerulosclerosis (FSGS) are emerging. Though the recommendations on treatment for COVID-19-associated respiratory symptoms are evolving, there is still no definitive treatment for the collapsing FSGS secondary to COVAN. We report a case of a 47-year-old male admitted with acute kidney injury from COVID-19 infection and found to have collapsing FSGS on renal biopsy.

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Introduction: Extended-release calcifediol (ERC), active vitamin D hormones and analogs (AVD) and nutritional vitamin D (NVD) are commonly used therapies for treating secondary hyperparathyroidism (SHPT) in adults with stage 3-4 chronic kidney disease (CKD) and vitamin D insufficiency (VDI). Their effectiveness for increasing serum total 25-hydroxyvitamin D (25D) and reducing elevated plasma parathyroid hormone (PTH), the latter of which is associated with increased morbidity and mortality, has varied across controlled clinical trials. This study aimed to assess real-world experience of ERC and other vitamin D therapies in reducing PTH and increasing 25D.

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This study shows a one-pot preparation of carbon dots by a solvothermal method in ethylene glycol. The carbon dots show yellow-colored fluorescence emission in water. The carbon dots showed distinct preference to be present in the hydrophobic environment which was evident from their efficient transfer from aqueous phase to organic phase.

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Kidney failure is common in patients with Coronavirus Disease-19 (COVID-19), resulting in increased morbidity and mortality. In an international collaboration, 284 kidney biopsies were evaluated to improve understanding of kidney disease in COVID-19. Diagnoses were compared to five years of 63,575 native biopsies prior to the pandemic and 13,955 allograft biopsies to identify diseases that have increased in patients with COVID-19.

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This study vividly displays the different self-assembling behavior and consequent tuning of the fluorescence property of a peptide-appended core-substituted naphthalenediimide (N1) in the aliphatic hydrocarbon solvents (-hexane/-decane/methyl cyclohexane) and in an aqueous medium within micelles. The N1 is highly fluorescent in the monomeric state and self-aggregates in a hydrocarbon solvent, exhibiting "H-type" or "face-to-face" stacking as indicated by a blue shift of absorption maxima in the UV-vis spectrum. In the H-aggregated state, the fluorescence emission of N1 changes to green from the yellow emission obtained in the monomeric state.

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This study demonstrates how the self-assembly pattern of two different and isomeric peptide-appended core-substituted naphthalenediimides (NDIs) affects the modulation of their optoelectronic properties. Two isomeric peptide-attached NDIs were synthesized, purified and characterized. Interchanging the position of attachment of the peptide units and the alkyl chains in the NDI has altered the respective self-assembling patterns of these isomeric molecules in the aggregated states.

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The present study convincingly demonstrates visible light induced continuous tuning of the fluorescence of carbon nanodots from yellow to cyan within two hours. These carbon dots are well characterized using field emission gun transmission electron microscopy (FEG-TEM), X-ray photoelectron spectroscopy (XPS), Fourier-transform infrared spectroscopy (FT-IR), fluorescence spectroscopy and UV-visible spectroscopy. Moreover, solid state fluorescence of different wavelengths has also been obtained from these colour tunable carbon dots by circumventing the common problem of aggregation induced quenching of fluorescence in the solid state.

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A novel blend of membranes made of Nafion and poly(vinylpyrrolidone) (PVP) was prepared and characterized to investigate its applicability in proton exchange membrane fuel cells (PEMFCs). In addition to being effectively proton conductive, the membranes exhibited better mechanical strength, chemical stability, and adequate water retention ability, as well as ion exchange capacity comparable to that of cast Nafion membrane. The data obtained from an electrochemical impedance spectroscopy (EIS) fitting of the fuel cells revealed the membrane electrode assemblies (MEAs) made of 0.

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This is a unique example of fluorescent carbon dot-induced hydrogelation of an amino acid-based amphiphile. The carbon dot-to-amphiphile ratio dictates the gel stiffness. Moreover, this hydrogel can be used as a prominent fluorescent ink and the dried gel shows a remarkable, unusual green fluorescence in the solid state.

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Article Synopsis
  • This study showcases how a specific peptide, attached to naphthalene diimide (NDI), self-assembles into a fluorescent structure in water, displaying unusual yellow fluorescence.
  • The aggregated form has been thoroughly analyzed using various techniques, including TEM and UV-vis spectroscopy, revealing a distinct nanofibrillar structure with improved fluorescence longevity compared to its non-aggregated state.
  • Notably, the fluorescence can be toggled on and off based on pH changes, making it a potential candidate for security applications like rewritable color codes in information encryption.
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A triphenylalanine-based superhydrogel shows automatic syneresis (self-compressing properties) with time and this self-shrinking behavior has been successfully utilized to remove toxic lead ions and organic dyes from waste-water efficiently with the ability to re-use for a few times.

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