Dr. Amitava Das - Profile on Academia.edu (original) (raw)

Papers by Dr. Amitava Das

ACS Applied Bio Materials, 2019

Designing vehicles to protect occupants from explosive threats is complicated by the complex set ... more Designing vehicles to protect occupants from explosive threats is complicated by the complex set of physics that occurs from the point of detonation to the response of the occupants. These physics include detonation chemistry, shock physics, solid mechanics, structural dynamics, nonlinear material behaviour, and human physiology and injury mechanics, among others. Consequently, vehicles are typically developed through an iterative process of destructive field testing in order to determine the level of blast protection. This testing is both time consuming and costly and does not ensure an optimized design. Recent advances in computational power and high-fidelity multi-physics computational tools now offer the alternative of performing Simulation-Based Design (SBD), similar to what is currently done for crash protection. Here, the explosive threat, its coupling to a vehicle, the vehicle structure, occupants or surrogates, and their coupling to the vehicle are all modelled in a single analysis. In this paper we describe an approach that applies state-of-the-art nonlinear finite element analysis to rapidly determine the survivability of vehicle designs and occupant injury potential when subjected to a buried charge or an above-ground improvised explosive device (IED). This integrated analysis capability allows iterative assessments to be performed as part of the design process. Modelling approaches for buried charges and IEDs and the coupling of the resulting loads on the vehicle are discussed. Finally, detailed sub-modelling of critical components such as occupant seating systems is demonstrated.

Chemical communications (Cambridge, England), May 4, 2016

We report a new chemodosimetric reagent capable of detecting hydrazine in the presence of several... more We report a new chemodosimetric reagent capable of detecting hydrazine in the presence of several other competing amine derivatives and ionic analytes of biological relevance. This reagent has been utilized for real time monitoring of in situ N2H4 release during the metabolism of a crucial tuberculosis drug, isoniazid, in live HepG2 cells. The fluorescence response of the reagent based on its specific reaction with N2H4 is used for developing an in vitro assay for aminoacylase-1.

Journal of the Ceramic Society of Japan, 2009

Chalcopyrite compounds/fullerene solar cells based on copper-indium-disulphide and C60 were produ... more Chalcopyrite compounds/fullerene solar cells based on copper-indium-disulphide and C60 were produced. Two-types of devices with heterojunction and bulk heterojunction structures were examined and characterized. The bulk heterojunction structure provided better efficiency compared to that of the heterojunction structure. Nanostructures of the solar cells were confirmed as mixed nanocrystals by transmission electron microscopy. A photovoltaic mechanism of the present solar cells was discussed on the basis of the experimental results.

Synthesis, Characterization and Physico-chemical Properties of New 2-(4- Arylpiperazine-1-yl)-1-(3-methylbenzofuran-2-yl)ethanoles as Potential Antihypertensive Agents

Current Organic Chemistry, 2009

ABSTRACT

Demonstrating the role of anchoring functionality in interfacial electron transfer dynamics in the newly synthesized BODIPY–TiO₂ nanostructure composite

New Journal of Chemistry, 2017

Scheme illustrating the extent of coupling and charge recombination dynamics between BODIPY and N... more Scheme illustrating the extent of coupling and charge recombination dynamics between BODIPY and NS-TiO2 anchoring through the catechol and resorcinol binding group.

Chemical Communications, 2019

HAL is a multi-disciplinary open access archive for the deposit and dissemination of scientific r... more HAL is a multi-disciplinary open access archive for the deposit and dissemination of scientific research documents, whether they are published or not. The documents may come from teaching and research institutions in France or abroad, or from public or private research centers. L'archive ouverte pluridisciplinaire HAL, est destinée au dépôt et à la diffusion de documents scientifiques de niveau recherche, publiés ou non, émanant des établissements d'enseignement et de recherche français ou étrangers, des laboratoires publics ou privés.

Journal of Materials Chemistry B, 2016

Two-photon imaging of endogenous bisulphite ions of the hippocampus region of mouse brain.

Inorganic chemistry, Jan 21, 2016

A new 4,4-difluoro-4-bora-3a,4a-diaza-s-indacene (BODIPY)-based probe molecule (L) is synthesized... more A new 4,4-difluoro-4-bora-3a,4a-diaza-s-indacene (BODIPY)-based probe molecule (L) is synthesized for specific binding to Hg(2+) ion in physiological condition with an associated luminescence ON response in the near-IR region of the spectrum. Appropriate functionalization in the 5-position of each of two pyrrole moieties with styryl functionality in a BODIPY core helped us in achieving the extended conjugation and a facile intramolecular charge transfer transition with a narrow energy gap for frontier orbitals. This accounted for a poor emission quantum yield for the probe molecule L. Binding to Hg(2+) helped in interrupting the facile intramolecular charge transfer (ICT) process that was initially operational for L. This resulted in a hypsochromic shift of absorption band and a turn-on luminescence response with λMax(Ems) of 650 nm on specific binding to Hg(2+). Observed spectral changes are rationalized based on quantum chemical calculations. Interestingly, this reagent is found t...

Chemical communications (Cambridge, England), Jan 28, 2018

A new physiologically benign and cell membrane permeable BODIPY based molecular probe, MB-Sn, spe... more A new physiologically benign and cell membrane permeable BODIPY based molecular probe, MB-Sn, specifically senses intracellular hydrogen polysulfides (H2Sn, n > 1) localized in the endoplasmic reticulum. This reagent is suitable for mapping the intracellular distribution of H2Sn by wide-field as well as super-resolution Structured Illumination Microscopy (SIM).

Analytical chemistry, Dec 20, 2016

Reagents that allows detection and monitoring of crucial biomarkers with luminescence ON response... more Reagents that allows detection and monitoring of crucial biomarkers with luminescence ON response have significance in clinical diagnostics. A new coumarin derivative is reported here, which could be used for specific and efficient chemodosimetric detection of cysteine, an important biomarker. The probe is successfully used for studying the biochemical transformation of N-acetylcysteine, a commonly prescribed Cys supplement drug to Cys by aminoacylase-1 (ACY-1), an important and endogenous mammalian enzyme. The possibility of using this reagent for quantification of ACY-1 in blood serum samples is also explored. Nontoxic nature and cell membrane permeability are key features of this probe and are ideally suited for imaging intracellular Cys in normal and cancerous cell lines. Our studies have also revealed that this reagent could be utilized as a redox switch to monitor the hydrogen-peroxide-induced oxidative stress in living SW480 cell lines. Peroxide-mediated cysteine oxidation ha...

Chemical Communications, 2015

Use of a cysteine specific chemodosimetric receptor for probing its release in the ER-region of t... more Use of a cysteine specific chemodosimetric receptor for probing its release in the ER-region of the HepG2 cells during drug metabolism and silica based strips for quantitative estimation of Cys in a human blood plasma sample.

Scientific Reports, 2019

Creation of hollow, one-dimensional nanomaterials has gained great recent attention in the chemic... more Creation of hollow, one-dimensional nanomaterials has gained great recent attention in the chemical and material sciences. In a study aimed at discovering new functional materials of this type, we observed that an amphiphilic diacetylene (DA) derivative, containing an azobenzene moiety and an oligo-ethylene group, self-assembles to form nanotubes and undergoes photopolymerization to form hollow polydiacetylene (PDA) nanotubes with a uniform wall thickness and diameter. The azobenzene-PDA nanotubes are photoresponsive in that on-and-off UV-irradiation leads to a reversible morphological change between straight and bent forms in association with E-Z photoisomerization of the azobenzene group. Owing to the UV-induced structural change feature, the new DA and PDA nanotubes serve as a controlled release material. Accordingly, fluorescent rhodamine B encapsulated inside the nanotubes are effectively released by using repeated on-off UV irradiation. Furthermore, photo-release of rhodamine ...

Bioconjugate Chemistry, 2018

Sumit Kumar Pramanik and Sreejesh Sreedharan has equal contribution. Cell studies for Nanocapsule... more Sumit Kumar Pramanik and Sreejesh Sreedharan has equal contribution. Cell studies for Nanocapsules Cellular Uptake experiments of the nanocapsules (Single colour SIM/ Wide Field/

Chemical communications (Cambridge, England), Jan 23, 2017

β-NaYF4:Yb,Gd up-conversion nanoparticles, UCNPs, surface functionalized with suitable targetting... more β-NaYF4:Yb,Gd up-conversion nanoparticles, UCNPs, surface functionalized with suitable targetting peptides function as nontoxic lysosome-specific imaging probes.

Analytical chemistry, Jan 26, 2017

Selective detection of nitroxyl (HNO), which has recently been identified as a reactive nitrogen ... more Selective detection of nitroxyl (HNO), which has recently been identified as a reactive nitrogen species, is a challenging task. We report a BODIPY-based luminescence ON reagent for detection of HNO in aqueous solution and in live RAW 264.7 cells, based on the soft nucleophilicity of the phosphine oxide functionality towards HNO. The probe shows high selectivity to HNO over other reactive oxygen/nitrogen and sulphur species. Luminescence properties of the BODIPY based chemodosimetric reagent make it an ideal candidate for use as a reagent for super resolution structured illumination microscopy. The viability of the reagent for biological in-vivo imaging application was also confirmed using Artemia as a model.

Counteranion Driven Homochiral Assembly of a Cationic C3-Symmetric Gelator through Ion-Pair Assisted Hydrogen Bond

Journal of the American Chemical Society, 2016

The helical handedness in achiral self-assemblies is mostly complex due to spontaneous symmetry b... more The helical handedness in achiral self-assemblies is mostly complex due to spontaneous symmetry breaking or kinetically controlled random assembly formation. Here an attempt has been made to address this issue through chiral anion exchange. A new class of cationic achiral C3-symmetric gelator devoid of any conventional gelation assisting functional units is found to form both right- and left-handed helical structures. A chiral counteranion exchange-assisted approach is successfully introduced to control the chirality sign and thereby to obtain preferred homochiral assemblies. Formation of anion-assisted chiral assembly was confirmed by circular dichroism (CD) spectroscopy, microscopic images, and crystal structure. The X-ray crystal structure reveals the construction of helical assemblies with opposite handedness for (+)- and (-)-chiral anion reformed gelators. The appropriate counteranion driven ion-pair-assisted hydrogen-bonding interactions are found responsible for the helical bias control in this C3-symmetric gelator.

GSH Induced Controlled Release of Levofloxacin form a Pur-pose-built Prodrug: Luminescence Response for Probing the Drug Release in E-coli and Staphylococcus aureus

Bioconjugate chemistry, Sep 9, 2016

Fluoroquinolones are 3rdgeneration broad spectrum bactericidal antibiotics and work against both ... more Fluoroquinolones are 3rdgeneration broad spectrum bactericidal antibiotics and work against both gram positive and gram negative bacteria. Levofloxacin (L), a fluoroquinolone, is widely used in anti-infective chemotherapy, urinary tract infection and treating pneumonia. The main pathogen for urinary tract infections is Escherichia coli and Streptococcus pneumoniae is responsible for the pneumonia, predominantly a lower respiratory tract infection. Poor permeability of L leads to the use of higher dose of this drug and excess drug exists in the outer cellular fluid leads to central nervous system (CNS) abnormality. One way to counter this is to improve the lipophilicity of the drug molecule and accordingly, we have synthesized two new Levofloxacin derivatives, which participated in the spatiotemporal release of drug via disulfide bond cleavage induced by glutathione (GSH). Recent studies with Streptococcus mutants suggest that it is localized in epithelial lining fluid (ELF) of the n...

Journal of Materials Chemistry B, 2013

The size distribution of the octadecyl rhodamine-6G (5.0 x 10-5 M) in waterethanol (4:1, v/v) media.