Other affiliations: Indian Institute of Technology Bombay
Bio: Amit Kumar is an academic researcher from Indian Institute of Technology Madras. The author has contributed to research in topics: Flame spread & Diffusion flame. The author has an hindex of 12, co-authored 70 publications receiving 547 citations. Previous affiliations of Amit Kumar include Indian Institute of Technology Bombay.
Papers published on a yearly basis
TL;DR: To the authors' knowledge this is the first copper complex that causes cell death by interacting with HPV oncoprotein followed by exhibition of remarkable antiproliferative activity.
Abstract: Metallo-organic compounds are interesting to study for their antitumor activity and related applications. This paper deals with the syntheses, characterization, structure determination of a copper complex of anthracenyl terpyridine (1) and its plasmid cleavage and cytotoxicity towards different cancer cell lines. The complex binds CT-DNA through partial intercalation mode. The plasmid cleavage studies carried out using pBR322 and pUC18 resulted in the formation of all the three forms of the plasmid DNA. Plasmid cleavage studies carried out with a non-redoxable Zn(2+) complex (2) supported the role of the redox activity of copper in 1. The complex 1 showed remarkable antiproliferative activity against cancer cell lines, viz., cervical (HeLa, SiHa, CaSki), breast (MCF-7), liver (HepG2) and lung (H1299). A considerable lowering was observed in the IC(50) values of HPV-infected (viz., HeLa, SiHa, CaSki) vs. non-HPV-infected cell lines (MCF-7, HepG2, H1299). Antiproliferative activity of 1 was found to be much higher than the carboplatin when treated with the same cell lines. Incubation of the cells with 1 results in granular structures only with the HPV-infected cells and not with others as studied by phase contrast and fluorescence microscopy. The lower IC(50) value observed in case of 1 with HPV-infected cell lines may be correlated with the involvement of HPV oncoprotein. The role of HPV has been further augmented by transfecting the MCF-7 cells (originally not possessing HPV copy) with e6 oncoprotein cDNA. To our knowledge this is the first copper complex that causes cell death by interacting with HPV oncoprotein followed by exhibition of remarkable antiproliferative activity.
TL;DR: Material studies carried out by using fluorescence microscopy, SEM, and AFM techniques showed that the hexaporphyrinato cyclotriphosphazene systems form ringlike architectures.
Abstract: A simple method has been employed to synthesize a cyclotriphos- phazene appended with six porphyrins. The reaction of one equivalent of hexa- chlorocyclotriphosphazene with six equivalents of 5-(4-hydroxyphenyl)- 10,15,20-triAp-tolyl)porphyrin or -21- thiaporphyrin in tetrahydrofuran in the presence of cesium carbonate, followed by simple column-chromatography pu- rification, afforded the hexaporphy- A cyclotriphosphazene systems as the single products in 80-90 % yields. The metal(II) derivatives (Cu II ,Z n II )o f the hexaporphyrinato cyclotriphospha- zene systems were prepared by treating the hexaporphyrin assemblies with the appropriate metal salts under standard metallation conditions. The compounds are freely soluble in common organic solvents and were characterized by mass spectrometry, NMR, absorption, and fluorescence spectroscopy, and electrochemical techniques. Material studies carried out by using fluores- cence microscopy, SEM, and AFM techniques showed that the hexapor- phyrinato cyclotriphosphazene systems form ringlike architectures. Preliminary biological studies indicate that the hexaA porphyrin assembly can be used as an artificial nuclease.
TL;DR: The present studies clearly demonstrated the recognition features of [ZnL] toward Asp, Cys, His, and Glu, and the peptides and proteins containing these by spectroscopy and microscopy studies.
Abstract: A lower rim naphthylidene conjugate of calixarene [L] has been synthesized and characterized, and the structure has been established on the basis of single crystal XRD. The L has been found to be selective toward Zn(2+), which induces appropriate changes in the arms of L so that the N(2)O(2) coordination results in the formation of a tetrahedral complex; namely, [ZnL]. [ZnL] recognizes Asp, Cys, His, and Glu from among the naturally occurring amino acids owing to the protonation and chelating ability of the amino acid and the pi-pi interaction ability of the side chain of the amino acid with [ZnL]. All of these features have been demonstrated on the basis of fluorescence, absorption, and lifetime measurements. The rechelation of Zn(2+) by the amino acid used in the titration has been demonstrated on the basis of ESI-MS studies in the case of Cys to result in a Zn(2+) complex having either 5- or 6-coordination. [ZnL] has also been shown to be selective toward glutathione and glutathione oxidized. The amino acids present in the proteins also interact with [ZnL], resulting in dechelation of [ZnL] as well as aggregation of the protein, as demonstrated on the basis of absorption and fluorescence spectroscopy and atomic force microscopy. The alpha-helical proteins (namely, albumins) exhibit greater conformational changes, as compared to the beta-sheet proteins (namely, lectins), as studied on the basis of CD spectroscopy. The aggregation of the proteins when treated with [ZnL] follows a trend: peanut agglutinin < bovine serum albumin < jacalin < human serum albumin. The present studies clearly demonstrated the recognition features of [ZnL] toward Asp, Cys, His, and Glu, and the peptides and proteins containing these by spectroscopy and microscopy studies.
TL;DR: In this work, single-port, cylindrical grain laboratory-scale hybrid rocket motors are numerically simulated to study the effect of diaphragms.
Abstract: In this work, single-port, cylindrical grain laboratory-scale hybrid rocket motors are numerically simulated to study the effect of diaphragms. The effect of single and multiple diaphragms is investigated by varying diaphragm height, its axial location (for a single diaphragm), and spacing (for multiple diaphragms) at selected inlet GOX. A single diaphragm increases the local regression rate and its influence is prominent only in the region immediate downstream. Therefore, a tangible increment in average regression rate with a single diaphragm can only be realized for motors with small L/D( 10), use of multiple diaphragms are required to increase the regression rate and combustion effici...
TL;DR: In this paper, a flame spread model is formulated in three dimensions to simulate opposed flow flame spread over thin solid fuels, coupled with a three-dimensional gas radiation model to assess the role of radiation and effect of dimensionality on the prediction of the flame spread phenomena.
Abstract: In this work a flame-spread model is formulated in three dimensions to simulate opposed flow flame spread over thin solid fuels. The flame-spread model is coupled to a three-dimensional gas radiation model. The experiments  on downward spread and zero gravity quiescent spread over finite width thin fuel are simulated by flame-spread models in both two and three dimensions to assess the role of radiation and effect of dimensionality on the prediction of the flame-spread phenomena. It is observed that while radiation plays only a minor role in normal gravity downward spread, in zero gravity quiescent spread surface radiation loss holds the key to correct prediction of low oxygen flame spread rate and quenching limit. The present three-dimensional simulations show that even in zero gravity gas radiation affects flame spread rate only moderately (as much as 20% at 100% oxygen) as the heat feedback effect exceeds the radiation loss effect only moderately. However, the two-dimensional model with the gas radi...
TL;DR: There is, I think, something ethereal about i —the square root of minus one, which seems an odd beast at that time—an intruder hovering on the edge of reality.
Abstract: There is, I think, something ethereal about i —the square root of minus one. I remember first hearing about it at school. It seemed an odd beast at that time—an intruder hovering on the edge of reality. Usually familiarity dulls this sense of the bizarre, but in the case of i it was the reverse: over the years the sense of its surreal nature intensified. It seemed that it was impossible to write mathematics that described the real world in …
TL;DR: The Thermophysical Properties Research Literature Retrieval Guide as discussed by the authors was published by Y. S. Touloukian, J. K. Gerritsen and N. Y. Moore.
Abstract: Thermophysical Properties Research Literature Retrieval Guide Edited by Y. S. Touloukian, J. K. Gerritsen and N. Y. Moore Second edition, revised and expanded. Book 1: Pp. xxi + 819. Book 2: Pp.621. Book 3: Pp. ix + 1315. (New York: Plenum Press, 1967.) n.p.
01 Dec 1988
TL;DR: In this paper, the basic processes in Atomization are discussed, and the drop size distributions of sprays are discussed.Preface 1.General Considerations 2.Basic Processes of Atomization 3.Drop Size Distributions of Sprays 4.Atomizers 5.Flow in Atomizers 6.AtOMizer Performance 7.External Spray Charcteristics 8.Drop Evaporation 9.Drop Sizing Methods Index
Abstract: Preface 1.General Considerations 2.Basic Processes in Atomization 3.Drop Size Distributions of Sprays 4.Atomizers 5.Flow in Atomizers 6.Atomizer Performance 7.External Spray Charcteristics 8.Drop Evaporation 9.Drop Sizing Methods Index