Soumen Mandal

Bio: Soumen Mandal is an academic researcher from Central Mechanical Engineering Research Institute. The author has contributed to research in topics: Machining & Fiber Bragg grating. The author has an hindex of 10, co-authored 43 publications receiving 256 citations. Previous affiliations of Soumen Mandal include Academy of Scientific and Innovative Research & Council of Scientific and Industrial Research.

Novel synthesis of a mixed Cu/CuO–reduced graphene oxide nanocomposite with enhanced peroxidase-like catalytic activity for easy detection of glutathione in solution and using a paper strip

Abstract: A reduced graphene oxide (rGO) based mixed copper nanocomposite, Cu/CuO–rGO is prepared through a novel synthetic approach: a simple one-step oxidation–reduction reaction between aqueous graphene oxide (GO) and copper(II) chloride (CuCl2) solutions at ambient temperature and pressure. The nanocomposite shows enhanced peroxidase-like catalytic activity by rapidly catalyzing a TMB (3,3′,5,5′-tetramethyl benzidine)–H2O2 reaction that develops a visible blue color in solution due to the oxidation of TMB. The catalyst follows a Michaelis–Menten reaction mechanism and exhibits strong affinity towards both H2O2 and TMB. The blue color developed by the Cu/CuO–rGO–TMB–H2O2 system becomes colorless in solution when glutathione is present even at a very low concentration (0.032 μM). This distinct color change provides the basis of the present colorimetric method for highly sensitive and selective detection of GSH in solution as well as on a paper-strip within a <5 min time period. The use of Cu/CuO–rGO as an enzyme-like catalyst in TMB–H2O2 mediated GSH sensing process shows the benefits of simplicity, cost-effectiveness and provides an alternative non-enzymatic way of glutathione estimation in real samples such as commercially available tablets and human blood plasma.

Flexible NO2 gas sensor based on single-walled carbon nanotubes on polytetrafluoroethylene substrates

Abstract: This paper presents a flexible and reliable chemiresistor-type NO2 gas sensor based on single-walled carbon nanotubes (SWNTs) on polytetrafluoroethylene (PTFE) membrane filter substrates. The sensor is realized by using a cost-effective spray coating in the preparation of SWNTs thin film, followed by the fabrication of metal contacts using a shadow mask and polyethyleneimine (PEI) noncovalent functionalization of the SWNTs. This showed a high sensitivity to NO2 gas at room temperature in dry air; 21.58% to 167.7% for concentrations of 0.75 ppm to 5 ppm, and was almost nonsensitive to ammonia. Gas sensing characterization results, obtained for various substrate bending/wrapping over different cylinders with diameters of 75 mm, 12.5 mm, and 6 mm showed that bending does not significantly affect sensitivity for NO2 concentrations of 0.75 ppm to 2 ppm, while in the case of 3 ppm to 5 ppm NO2, the bent samples indicate enhanced sensitivity. This is probably because of the porous nature of PTFE substrates; these sensors were 1.5 to 2.7 times more sensitive than those fabricated over silicon substrate for 1 ppm and 5 ppm, respectively. Moreover, the relative humidity of 10% and 30% significantly reduced the sensitivity of the sensors. The presented results could be useful for the future development of flexible electronics/sensors for monitoring outdoor air quality and for the detection of volatile organic compounds.

Study of pore morphology, microstructure, and cell adhesion behaviour in porous Ti-6Al-4V scaffolds

Abstract: In the present work, dense Ti-6Al-4V sample and porous Ti-6Al-4V scaffolds were prepared using powder metallurgy route. Milled Ti-6Al-4V powder was blended with a space holder (ammonium bicarbonate), consolidated with and without binder (camphor) using uniaxial press and sintered at 1200 °C for 75 min in argon atmosphere. Space holder of different size fractions (− 250 + 212 and -300 + 250 μm) were obtained by sieving and used during blending. A maximum densification is achieved in the dense Ti-6Al-4V sample after sintering. The SEM micrograph of the dense Ti-6Al-4V sample confirms the presence of α- and β-phases. Porous Ti-6Al-4V scaffolds obtained after sintering show the density of about 60% theoretical. In all the porous scaffolds, the porosity of about 40% was achieved. This result is substantiated with the results from mercury porosimetry. Sinterability i.e. change in density from de-binding plus pre-sintering to sintering is observed to be the same in dense sample and porous scaffold prepared with a − 250 + 212 μm space holder. Micrographs of sintered porous scaffolds show presence of both macropores and micropores. Coalescence of macropores to form a large pore is also seen. An increase in the macropore size is observed when the sample is prepared with a certain space holder and binder. Also, a significant reduction of micropores within the solid networks is also seen in the binder-added samples. Finally, the cell attachment and viability studies using osteoblast-like MG63 on porous scaffolds show good cytocompatibility.

14-deoxyandrographolide desensitizes hepatocytes to tumour necrosis factor-alpha-induced apoptosis through calcium-dependent tumour necrosis factor receptor superfamily member 1A release via the NO/cGMP pathway.

Abstract: BACKGROUND AND PURPOSE Andrographis paniculata (AP) has been found to display hepatoprotective effect, although the mechanism of action of the active compounds of AP in this context still remains unclear. Here, we evaluated the hepatoprotective efficacy of 14-deoxyandrographolide (14-DAG), a bioactive compound of AP, particularly its role in desensitization of hepatocytes to tumour necrosis factor-alpha (TNF-α)-induced signalling of apoptosis. EXPERIMENTAL APPROACH TNF-α-mediated ligand receptor interaction in hepatocytes in the presence of 14-DAG was studied in vitro in primary hepatocyte cultures, with the help of co-immunoprecipitation, confocal microscopy and FACS analysis. Events associated with 14-DAG-induced TNFRSF1A release from hepatocytes were determined using immunoblotting, biochemical assay and fluorimetric studies. Pulse-chase experiments with radiolabelled TNF-α and detection of apoptotic nuclei by terminal transferase-mediated dUTP nick-end labelling were performed under in vivo conditions. KEY RESULTS 14-DAG down-regulated the formation of death-inducing signalling complex, resulting in desensitization of hepatocytes to TNF-α-induced apoptosis. Pretreatment of hepatocytes with 14-DAG accentuated microsomal Ca-ATPase activity through induction of NO/cGMP pathway. This resulted in enhanced calcium influx into microsomal lumen with the formation of TNFRSF1A–ARTS-1–NUCB2 complex in cellular vesicles. It was followed by the release of full-length 55 kDa TNFRSF1A and a reduction in the number of cell surface TNFRSF1A, which eventually caused diminution of TNF-α signal in hepatocytes. CONCLUSION AND IMPLICATION Taken together, the results demonstrate for the first time that 14-DAG desensitizes hepatocytes to TNF-α-mediated apoptosis through the release of TNFRSF1A. This can be used as a strategy against cytokine-mediated hepatocyte apoptosis in liver dysfunctions.

MEMS accelerometer: From engineering to medicine

Abstract: The earliest accelerometer found its industrial applications in 1923 and could measure the acceleration and vibration of industrial components. Because it weighed about 1 lb and was extremely large in size, no engineer could foresee its utility in mobile electronic devices. The device used a resistance bridge along with electronic circuitry to measure the acceleration and vibrations of intended objects. In addition to its bulkiness, the accelerometer had lower resonant frequency, was fragile, and possessed low frequency response.

Subspace model identification-Part 1. The output-error state-space model identification class of algorithms

Abstract: In this paper, we present two novel algorithms to realize a finite dimensional, linear time-invariant state-space model from input-output data. The algorithms have a number of common features. They are classified as one of the subspace model identification schemes, in that a major part of the identification problem consists of calculating specially structured subspaces of spaces defined by the input-output data. This structure is then exploited in the calculation of a realization. Another common feature is their algorithmic organization: an RQ factorization followed by a singular value decomposition and the solution of an overdetermined set (or sets) of equations. The schemes assume that the underlying system has an output-error structure and that a measurable input sequence is available. The latter characteristic indicates that both schemes are versions of the MIMO Output-Error State Space model identification (MOESP) approach. The first algorithm is denoted in particular as the (elementary MOESP scheme)...

Carbon Nanozymes: Enzymatic Properties, Catalytic Mechanism, and Applications.

Abstract: Nanozymes have advantages over natural enzymes, such as facile production on large scale, long storage time, low costs, and high stability in harsh environments. Carbon nanomaterials (CNMs), including fullerenes, carbon nanotubes, graphene, carbon quantum dots, and graphene quantum dots, have become a star family in materials science. As a new class of nanozymes, the catalytic activity of CNMs and their hybrids has been extensively reported. In this Minireview, recent progress of CNMs based artificial enzymes, focusing on those with peroxidase-like activity, has been summarized. The enzymatic properties, catalytic mechanisms, and novel applications of CNM nanozymes in sensing, therapy, and environmental engineering are discussed in detail. Additionally, we also highlight the remaining challenges and unsolved problems. With the fast development of bionanotechnology, the unique enzymatic properties and advantages of CNM nanozymes have received much attention and will continue to be an active and challenging field for the years to come.

Refractive index less than two: photonic nanojets yesterday, today and tomorrow [Invited]

Abstract: Materials with relatively small refractive indices (n<2), such as glass, quartz, polymers, some ceramics, etc., are the basic materials in most optical components (lenses, optical fibres, etc.). In this review, we present some of the phenomena and possible applications arising from the interaction of light with particles with a refractive index less than 2. The vast majority of the physics involved can be described with the help of the exact, analytical solution of Maxwell’s equations for spherical particles (so called Mie theory). We also discuss some other particle geometries (spheroidal, cubic, etc.) and different particle configurations (isolated or interacting) and draw an overview of the possible applications of such materials, in connection with field enhancement and super resolution nanoscopy.

A review on optical fiber sensors for environmental monitoring

Abstract: Environmental monitoring has become essential in order to deal with environmental resources efficiently and safely in the realm of green technology. Environmental monitoring sensors are required for detection of environmental changes in industrial facilities under harsh conditions, (e.g. underground or subsea pipelines) in both the temporal and spatial domains. The utilization of optical fiber sensors is a promising scheme for environmental monitoring of this kind, owing to advantages including resistance to electromagnetic interference, durability under extreme temperatures and pressures, high transmission rate, light weight, small size, and flexibility. In this paper, the optical fiber sensors employed in environmental monitoring are summarized for understanding of their sensing principles and fabrication processes. Numerous specific applications in petroleum engineering, civil engineering, and agricultural engineering are explored, followed by discussion on the potentials of OFS in manufacturing.

Andrographis paniculata (Burm. f.) Wall. ex Nees: a review of ethnobotany, phytochemistry, and pharmacology.

Abstract: As aboriginal sources of medications, medicinal plants are used from the ancient times. Andrographis paniculata is one of the highly used potential medicinal plants in the world. This plant is traditionally used for the treatment of common cold, diarrhoea, fever due to several infective cause, jaundice, as a health tonic for the liver and cardiovascular health, and as an antioxidant. It is also used to improve sexual dysfunctions and serve as a contraceptive. All parts of this plant are used to extract the active phytochemicals, but the compositions of phytoconstituents widely differ from one part to another and with place, season, and time of harvest. Our extensive data mining of the phytoconstituents revealed more than 55 ent-labdane diterpenoids, 30 flavonoids, 8 quinic acids, 4 xanthones, and 5 rare noriridoids. In this review, we selected only those compounds that pharmacology has already reported. Finally we focused on around 46 compounds for further discussion. We also discussed ethnobotany of this plant briefly. Recommendations addressing extraction process, tissue culture, and adventitious rooting techniques and propagation under abiotic stress conditions for improvement of phytoconstituents are discussed concisely in this paper. Further study areas on pharmacology are also proposed where needed.