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The pixel counting technique (PCT) has recently emerged as a promising method for the measurement of the dimensions of an object, showing significance in the applications like monitoring the traffic on roads, measuring the dimension of a... more
The pixel counting technique (PCT) has recently emerged as a promising method for the measurement of the dimensions of an object, showing significance in the applications like monitoring the traffic on roads, measuring the dimension of a biological sample, and many more. Therefore, measuring the accuracy of PCT is the topic of current research. The focus of our study is to evaluate the percentage error in the measurement of length, distance, and angle using PCT. The calculated maximum percentage errors in the length, distance, and angle measurements are 1.3%, 1.01%, and 3.9%, with maximum uncertainty due to repeatability of 0.4%, 0.29%, and 0.88%, respectively. The study outcomes conclude that the object visibility and illumination parameters play a significant role in estimating the uncertainty in the PCT-based object dimension calculations, especially angular measurements. This study will be beneficial for estimating the accuracy of PCT.
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This report describes the details of a recently upgraded spectral irradiance measurement facility in optical radiation standards at National Physical Laboratory, India. This facility provides the calibration of spectral irradiance in the... more
This report describes the details of a recently upgraded spectral irradiance measurement facility in optical radiation standards at National Physical Laboratory, India. This facility provides the calibration of spectral irradiance in the wavelength range 280 nm – 2500 nm. PTB, Braunschweig, Germany calibrated five numbers of 1000 W quartz halogen lamps, which are used as reference standards for spectral irradiance
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Fabrication, characterization and chemical modification of
The standing wave effect in positive photoresist has been found to be drastically reduced by using a thin coating of silicon nitride between the resist and the silicon dioxide film deposited on silicon substrate. The process modeling has... more
The standing wave effect in positive photoresist has been found to be drastically reduced by using a thin coating of silicon nitride between the resist and the silicon dioxide film deposited on silicon substrate. The process modeling has been carried out by adopting a method which is a natural extension of ANKAN, a computer program written for the exposure and development of a positive photoresist. The actual calculations have been performed for a line image exposure of AZ1350 photoresist by using the matrix formulation and diffraction limited system. The simulation allows the computation of resist profiles under a variety of experimental conditions. The analysis may be useful for a better linewidth control.
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Organic acids are important constituents of fruit juices. They render tartness, flavour and specific taste to fruit juices. Shelf life and stability of fruit juices are important factors, which determine their nutritional quality and... more
Organic acids are important constituents of fruit juices. They render tartness, flavour and specific taste to fruit juices. Shelf life and stability of fruit juices are important factors, which determine their nutritional quality and freshness. In this view, the effect of storage on the concentration of organic acids in commercially packed fruit juices is studied by reverse phase high performance liquid chromatography (RP-HPLC). Ten packed fruit juices from two different brands are stored at 30°C for 24, 48 and 72 hours. A reverse phase high performance liquid chromatographic method is used to determine the concentration of oxalic, tartaric, malic, ascorbic and citric acid in the fruit juices during storage. The chromatographic analysis of organic acids is carried out using mobile phase 0.5% (w/v) ammonium dihydrogen orthophosphate buffer (pH 2.8) on C18 column with UV-Vis detector. The results show that the concentration of organic acids generally decreases in juices under study wi...
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With an aim to circumvent intrinsic material bottleneck limitations of all optical switching this work presents a detailed experimental investigation of morphology directed photoinduced intermolecular interactions between an organic... more
With an aim to circumvent intrinsic material bottleneck limitations of all optical switching this work presents a detailed experimental investigation of morphology directed photoinduced intermolecular interactions between an organic fluorophore and four distinct gold nanoshapes.
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Nimustine, a chloroethyl nitrosourea derivative (CENU), is an antineoplastic agent, which is used for the treatment of various types of cancer. The present study focuses on the prediction and investigation of binding properties of... more
Nimustine, a chloroethyl nitrosourea derivative (CENU), is an antineoplastic agent, which is used for the treatment of various types of cancer. The present study focuses on the prediction and investigation of binding properties of nimustine with DNA using molecular modeling and UV–Visible spectroscopic technique. The docking study show that nimustine plausibly binds within the major groove of DNA. Further analysis of docking suggests direct interaction of nimustine with the moieties of heterocyclic nitrogenous bases of DNA. The free binding energy value of the best nimustine-DNA docked conformer is predicted as −4.31 kcal/mol using docking results.The molecular modeling study also reveals that the interaction between nimustine and DNA is majorly governed by van der Waals forces, hydrogen bonding and hydrophobic interactions, whereas the contribution of electrostatic forces stands negligible. Further, UV–Visible spectra of free calf thymus DNA and its complexes with varying concentration of nimustine indicate the binding constant (Ka) value as 3.27 × 103 M−1, which suggests moderate interaction of nimustine with DNA. The spectroscopic results are further used to calculate the binding free energy of the complex using the relation ΔG = −RTln (Ka). This accounts for a value of −4.79 kcal/mol. It corroborates well with the docking outcomes. The results of present study may help in designing and synthesis of new chloroethyl nitrosourea derivatives with improved efficacy and specificity for the target molecules.
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Molecular docking is a kind of computational modeling of the complexes, which is formed from the interaction of two or more molecules. It predicts the three-dimensional structure of adducts, based upon binding properties of participating... more
Molecular docking is a kind of computational modeling of the complexes, which is formed from the interaction of two or more molecules. It predicts the three-dimensional structure of adducts, based upon binding properties of participating ligand and target molecules. Molecular docking generates different possible candidate structures, which are ranked and grouped together using scoring function in the software of molecular docking tool. Docking simulations predict optimized docked conformer based upon total energy of the system. Various computational aspects of molecular docking with respect to its approaches and types are presented in this article.
This article discusses the DNA-interacting molecules and cancer treatments. A crucial step in reproduction is the passage of genetic information from the parent cell to the daughter cell. DNA replication starts with a double-stranded DNA... more
This article discusses the DNA-interacting molecules and cancer treatments. A crucial step in reproduction is the passage of genetic information from the parent cell to the daughter cell. DNA replication starts with a double-stranded DNA molecule and produces its two identical copies. The process of transcription commences by binding of an enzyme RNA polymerase (RNA Pol) to the template DNA strand. Noncovalent drug binding can be classified into two categories: DNA groove binders and intercalators. Numerous enzymes are involved in this important cellular event, namely, DNA polymerases, helicases, topoisomerases, primase, telomerase, recombination/repair enzymes, DNA ligase, endonucleases, exonucleases, and DNA-modifying enzymes (acetylases and methylases). The growth of cancer may be initiated by environmental agents (physical, chemical, radiation, and viruses) and inherited genetic mutations. Cancer immunotherapy exploits this property of immune system to treat cancer. Cancer immun...
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The pixel counting technique (PCT) has recently emerged as a promising method for the measurement of the dimensions of an object, showing significance in the applications like monitoring the traffic on roads, measuring the dimension of a... more
The pixel counting technique (PCT) has recently emerged as a promising method for the measurement of the dimensions of an object, showing significance in the applications like monitoring the traffic on roads, measuring the dimension of a biological sample, and many more. Therefore, measuring the accuracy of PCT is the topic of current research. The focus of our study is to evaluate the percentage error in the measurement of length, distance, and angle using PCT. The calculated maximum percentage errors in the length, distance, and angle measurements are 1.3%, 1.01%, and 3.9%, with maximum uncertainty due to repeatability of 0.4%, 0.29%, and 0.88%, respectively. The study outcomes conclude that the object visibility and illumination parameters play a significant role in estimating the uncertainty in the PCT-based object dimension calculations, especially angular measurements. This study will be beneficial for estimating the accuracy of PCT.
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Abstract Recently, developing convenient techniques for measuring the topological charge of vortex beam has garnered great interest. In the present paper, we analyze the inclined high-intensity rectangular pattern generated by... more
Abstract Recently, developing convenient techniques for measuring the topological charge of vortex beam has garnered great interest. In the present paper, we analyze the inclined high-intensity rectangular pattern generated by illuminating an elliptically squeezed conical phase with Laguerre-Gaussian beam for determining the topological charge. It is concluded that the separation in the horizontal vertices of the rectangular pattern offers a fixed variation ( ∼ 28 μ m in our case) with an integral change in the order of the beam, which remains invariant with the propagation distance. Further, the inclination of the pattern indicates the sign of the topological charge. The outcomes of this study are utilized for proposing a convenient technique for finding the topological charge of the vortex beam.
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Despite burgeoned knowledge about the origin, growth, tissue interactions, and spread of cancer in recent years, the functional complexity and unique survival ability of cancer cells still make it difficult to target them. Riviciclib is a... more
Despite burgeoned knowledge about the origin, growth, tissue interactions, and spread of cancer in recent years, the functional complexity and unique survival ability of cancer cells still make it difficult to target them. Riviciclib is a semi-synthetic derivative of rohitukine and possesses anticancer potential. Inhibition of nucleic acid activity in an uncontrolled dividing cell can form the basis for the development of new-age cancer therapeutics. The present study reports the molecular interaction between riviciclib and nucleic acid (DNA/tRNA) using spectroscopic and molecular docking studies in an attempt to comprehend its cellular toxicity as well as the nature and mode of binding between them. Vibrational spectroscopic results suggest that riviciclib intercalates DNA duplex and primarily binds with guanine, adenine, and thymine nucleobases. While in the case of riviciclib-tRNA complexation, riviciclib interacts mostly with uracil residues of the tRNA molecule. Besides nucleobases, riviciclib interacts with the sugar-phosphate backbone of both biomacromolecules. Conformationally, DNA alters from B-form to C-form, whereas tRNA shows no change in its native A-form. The order (104 M-1) of binding constant for riviciclib-nucleic acid complexation infer moderate to strong affinity of riviciclib with DNA and tRNA, respectively. Molecular docking explorations are further in corroboration with our spectroscopic outcomes.
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A dye (Eosin yellow) is adsorbed on distinct plasmonic structures, to investigate their morphology effect, on linear and third order nonlinear optical coefficients of plasmonic–organic hybrids for their potential use in optical switching.
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An experimental study was conducted to realize parallel optical digital operations using multiple beam interference in cascaded Mach–Zehnder and Michelson interferometers. Considering light intensity at different points of 2-D... more
An experimental study was conducted to realize parallel optical digital operations using multiple beam interference in cascaded Mach–Zehnder and Michelson interferometers. Considering light intensity at different points of 2-D interference pattern as output, which is controlled by intensity of two input beams in the arms of Mach–Zehnder and Michelson interferometers, respectively, two input multiple AND, OR, NAND, NOR, XOR and XNOR optical logic gates are demonstrated simultaneously. Further, a scheme was proposed to use these simultaneous logic operations, in designing integrated photonic circuits. Proposed scheme may have potential application in ultrafast information processing due to parallel multiple logic operations using the least number of electro-optic/all-optical switches, e.g. using only two photonic switches in the input arms in the present case.
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Chloroethyl nitrosourea derivatives (CENUs) represent an important family of anticancer chemotherapeutic agents, which are used in the treatment of different types of cancer such as brain tumors, resistant or relapsed... more
Chloroethyl nitrosourea derivatives (CENUs) represent an important family of anticancer chemotherapeutic agents, which are used in the treatment of different types of cancer such as brain tumors, resistant or relapsed Hodgkin's disease, small cell lung cancer and malignant melanoma. This work focuses towards understanding the interaction of chloroethyl nitrosourea derivatives; lomustine, nimustine and semustine with tRNA using spectroscopic approach in order to elucidate their auxiliary anticancer action mechanism inside the cell. Attenuated total reflection-Fourier transform infrared spectroscopy (ATR-FTIR), Fourier transform infrared difference spectroscopy, circular dichroism spectroscopy and UV-visible spectroscopy were employed to investigate the binding parameters of tRNA-CENUs complexation. Results of present study demonstrate that all CENUs, studied here, interact with tRNA through guanine nitrogenous base residues and possibly further crosslink cytosine residues in paired region of tRNA. Moreover, spectral data collected for nimustine-tRNA and semustine-tRNA complex formation indicates towards the groove-directed-alkylation as their anti-malignant action, which involves the participation of uracil moiety located in major groove of tRNA. Besides this, tRNA-CENUs adduct formation did not alter the native conformation of biopolymer and tRNA remains in A-form after its interaction with all three nitrosourea derivatives studied. The binding constants (Ka) estimated for tRNA complexation with lomustine, nimustine and semustine are 2.55×10(2)M(-1), 4.923×10(2)M(-1) and 4.223×10(2)M(-1) respectively, which specify weak type of CENU's binding with tRNA. Moreover, molecular modeling simulations were also performed to predict preferential binding orientation of CENUs with tRNA that corroborates well with spectral outcomes. The findings, presented here, recognize tRNA binding properties of CENUs that can further help in rational designing of more specific and efficient RNA targeted chemotherapeutic agents.
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Mitoxantrone (1,4-dihydroxy-5,8-bis[[2-[(2-hydroxyethyl)amino]ethyl]amino]-9,10-anthracenedione) is a synthetically designed antineoplastic agent and structurally similar to classical anthracyclines. It is widely used as a potent... more
Mitoxantrone (1,4-dihydroxy-5,8-bis[[2-[(2-hydroxyethyl)amino]ethyl]amino]-9,10-anthracenedione) is a synthetically designed antineoplastic agent and structurally similar to classical anthracyclines. It is widely used as a potent chemotherapeutic component against various kinds of cancer and possesses lesser cardio-toxic effects with respect to naturally occurring anthracyclines. In the present study, we have investigated the binding features of mitoxantrone-tRNA complexation at physiological pH using attenuated total reflection-Fourier transform infrared (ATR-FTIR) spectroscopy, circular dichroism (CD) spectroscopy, isothermal titration calorimetry, and UV-visible absorption spectroscopic techniques. FTIR analysis reveals that mitoxantrone interacts mainly with heterocyclic base residues of tRNA along with slight external binding with phosphate-sugar backbone. In particular, mitoxantrone binds at uracil (C=O) and adenine (C=N) sites of biomolecule (tRNA). CD spectroscopic results suggest that there is no major conformational transition in native A-form of tRNA upon mitoxantrone-tRNA adductation except an intensification in the secondary structure of tRNA is evident. The association constant calculated for mitoxantrone-tRNA association is found to be 1.27 × 10(5) M(-1) indicating moderate to strong binding affinity of drug with tRNA. Thermodynamically, mitoxantrone-tRNA interaction is an enthalpy-driven exothermic reaction. Investigation into drug-tRNA interaction can play an essential role in the rational development of RNA targeting chemotherapeutic agents, which also delineate the structural-functional relationship between drug and its target at molecular level.
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Anthracene based nano/microstructures of different sizes and shapes like tubes/fibers are synthesized using a simple open air chemical vapor deposition technique. Thermal solid phase reaction between anthracene 9-carboxylic acid and... more
Anthracene based nano/microstructures of different sizes and shapes like tubes/fibers are synthesized using a simple open air chemical vapor deposition technique. Thermal solid phase reaction between anthracene 9-carboxylic acid and calcium oxide reported recently [H. Liu et al., J. Am. Chem. Soc.125, 10794 (2003)] is used to obtain organic molecular nanostructures. The products of temperature (320 °C) induced reaction get deposited on the substrates placed inside the reaction chamber as well as on the inner walls in different nano/micrometer forms, tubes/rods/fibers and having different sizes. Structural characterization of the reaction products is performed using optical microscopy, field emission electron microscopy (FE-SEM) and transmission electron microscopy (TEM). Chemical composition studies are conducted using infrared (IR), nuclear magnetic resonance (NMR), and gas chromatography (GC)-Mass spectroscopy, as well as elemental analysis. IR studies of the nanostructures obtained on the substrate using IR spectroscopy reveal the presence of C=O groups, the confirmatory evidence of which is obtained using energy dispersive x-ray spectroscopic (EDS) analysis. Interaction study of the C=O groups with ammonia vapor is conducted and resulting changes are monitored using Fourier transform infrared (FTIR). A strong covalent modification of anthracene based structures by exposure to ammonia molecules is indicated.
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For a proper understanding and interpretation of the changes in the power spectral characteristics of surface EMG from any fatigued muscle of a worker employed on repetitive assembly line tasks, it is important to study first the changes... more
For a proper understanding and interpretation of the changes in the power spectral characteristics of surface EMG from any fatigued muscle of a worker employed on repetitive assembly line tasks, it is important to study first the changes in the spectral characteristic of the surface EMG of the same muscle of the worker assigned with non-repetitive tasks. The information obtained from the EMG study with non-repetitive tasks would serve as a control to identify and evaluate the changes in the power spectral features of the surface EMG of the muscle due to, in particular, the repetitive nature of the task under similar work environment. In this study the EMG signals from thenar fascia and biceps of two healthy workers engaged in non-repetitive tasks in an electronic industry have been recorded in the morning (before the start of the work) and again the evening (after the completion of day's work). The frequency wise distribution of the number of peaks (NP) and the power content (PC) of the signal have been evaluated within the range of 60-200 Hz. It is found that there is no significant difference in the frequency wise distribution of NP and PC in the power spectrum of the EMG signals recorded in the morning and evening.
Research Interests: Engineering, Ergonomics, Electrophysiology, Skeletal muscle biology, Humans, and 12 moreMale, Arm, Electromyography, Clinical Neurophysiology and Electromyography, Adult, Power Spectrum, Muscle Fatigue, Hand, Muscle contraction, Electronics Industry, Psychology and Cognitive Sciences, and Medical and Health Sciences
Research Interests: Pharmacy()
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Certain plant derived alkaloids and flavonoids have shown propitious cytotoxic acitvity against different types of cancer, having DNA as their main cellular target. Flavopiridol, a semi-synthetic derivative of rohitukine (a natural... more
Certain plant derived alkaloids and flavonoids have shown propitious cytotoxic acitvity against different types of cancer, having DNA as their main cellular target. Flavopiridol, a semi-synthetic derivative of rohitukine (a natural compound isolated from Dysoxylum binectariferum plant), has attained much attention owing to its anticancer potential against various hematological malignancies and solid tumors. This work focuses on investigating interaction between flavopiridol and DNA at molecular level in order to decipher its underlying mechanism of action, which is not well understood. To define direct influence of flavopiridol on the structural, conformational and thermodynamic aspects of DNA, various spectroscopic and calorimetric techniques have been used. ATR-FTIR and SERS spectral outcomes indicate a novel insight into groove-directed-intercalation of flavopiridol into DNA via direct binding with nitrogenous bases guanine (C6=O6) and thymine (C2=O2) in DNA groove together with ...