Newman College

Thodupuzha, India

Newman College

Thodupuzha, India
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Cheruvalath A.,Cochin University of Science and Technology | Sebastian I.,Newman College | Sebastian M.,Cochin University of Science and Technology | Nampoori V.P.N.,Cochin University of Science and Technology | Thomas S.,Cochin University of Science and Technology
Optical Materials | Year: 2017

In this work, we report the linear and nonlinear optical studies on a pseudo binary chalcogenide glass of composition Ge20 Se70 Te10 in its nano colloidal form. The possibility of tuning the band gap, nonlinear refractive index and nonlinear absorption of the material by changing the glass loading in the colloid has been revealed. A red shift in the band edge along with an intermediate peak in the band tail due to defect states is observed with increasing concentration. Photoluminescence studies confirm the existence of intermediate defect states in the bandgap. Nonlinear properties analyzed with open and closed aperture z scan technique reveal that the nonlinear refraction enhances due to resonant effects as the band gap of the colloid gets near the one photon absorption edge. The nonlinear absorption is prominent in the concentrated sample due to the presence of defect states which acts as an intermediate level in two step photon absorption. © 2017 Elsevier B.V.

Bagchi J.,Inter-University Center for Astronomy and Astrophysics | Sankhyayan S.,Indian Institute of Science | Sarkar P.,National Institute of Technology Jamshedpur | Raychaudhury S.,Inter-University Center for Astronomy and Astrophysics | And 2 more authors.
Astrophysical Journal | Year: 2017

Here we report the discovery of an extremely massive and large supercluster (called Saraswati5) found in the Stripe 82 region of SDSS. This supercluster is a major concentration of galaxies and galaxy clusters, forming a wall-like structure spanning at least 200 Mpc across at redshift z ≈ 0.3. This enormous structure is surrounded by a network of galaxy filaments, clusters, and large, ∼40-170 Mpc diameter, voids. The mean density contrast δ (relative to the background matter density of the universe) of Saraswati is ≳1.62 and the main body of the supercluster comprises at least 43 massive galaxy clusters (mean z = 0.28) with a total mass of ∼2 × 1016 Modot;. The spherical collapse model suggests that the central region of radius ∼20 Mpc and mass at least 4 × 1015 Modot; may be collapsing. This places it among the few largest and most massive superclusters known, comparable to the most massive "Shapley Concentration" (z ≈ 0.046) in the nearby universe. The Saraswati supercluster and its environs reveal that some extreme large-scale, prominent matter density enhancements formed ∼4 Gyr in the past when dark energy had just started to dominate structure formation. This galactic concentration sheds light on the role of dark energy and cosmological initial conditions in supercluster formation, and tests the competing cosmological models. © 2017. The American Astronomical Society. All rights reserved.

Chirayil C.J.,Newman College | Joy J.,Newman College | Mathew L.,Newman College | Mozetic M.,Jozef Stefan Institute | And 2 more authors.
Industrial Crops and Products | Year: 2014

In this work, cellulose nanofibrils were extracted from isora fiber by steam explosion method. The technique adopted includes alkaline treatment, bleaching, acidic steam treatment and homogenization. The material obtained after each stage of the treatments was carefully characterized and its chemical composition was determined. Morphological investigation was performed using scanning electron microscopy (SEM), atomic force microscopy (AFM) and transmission electron microscopy (TEM). Fourier transform infrared (FTIR) spectroscopy showed the progressive removal of noncellulosic constituents. X-ray diffraction (XRD) analysis revealed that the crystallinity increased with successive treatments. The thermal stability of the fibers was investigated using thermogravimetric analysis (TGA). The results showed that the prepared cellulose nanofibers showed nanofibrillar network like structure with high crystallinity (90%) and good thermal stability. © 2014 Elsevier B.V.

Chirayil C.J.,Newman College | Mathew L.,Newman College | Hassan P.A.,Bhabha Atomic Research Center | Mozetic M.,Jozef Stefan Institute | Thomas S.,Mahatma Gandhi University
International Journal of Biological Macromolecules | Year: 2014

Nanocellulose (NC) reinforced unsaturated polyester (UPR) composites were prepared by mechanical mixing process. Effect of isora nanocellulose on the properties of polyester composites has been studied in detail. Rheological properties of unsaturated polyester resin suspensions containing various amounts (0.5, 1 and 3. wt%) of nanocellulose were investigated by oscillatory rheometer with parallel plate geometry. Analysis of curing revealed that the time required for gelation in NC filled UPR is lower than neat resin, which describe the catalytic action of NC on cure reaction. NC reinforced polyester suspensions showed shear thinning behaviour initially and at higher shear rates they showed Newtonian behaviour. Tensile and impact properties showed superior behaviour revealing improved interfacial bonding between nanofiller and the polymer matrix. With respect to the neat polyester the percentage increase in tensile strength of 0.5. wt% NC reinforced composite is 57%. Optical and atomic force microscopic studies confirmed that the dispersion state of NC within the polyester matrix was adequate. Maximum glass transition temperature is obtained for 0.5. wt% NC reinforced composite, which showed an increase of 10. °C than neat resin. © 2014 Elsevier B.V.

Chirayil C.J.,Newman College | Joy J.,Newman College | Mathew L.,Newman College | Koetz J.,Institute For Chemie | Thomas S.,Mahatma Gandhi University
Industrial Crops and Products | Year: 2014

Isora nanofibrils (INFs) were extracted from Helicteres isora plant by steam explosion process and the resulting fibers were analyzed by transmission electron microscopy (TEM). It is observed that nanofibrils showed network like structure with a length of 300nm, width of 20nm and an aspect ratio of 15. Then these nanofibrils were incorporated into unsaturated polyester (UPR) by conventional mechanical mixing process. Higher aspect ratio of the prepared nanofibrils led to improved network in the polyester matrix and this resulted in good mechanical properties of the prepared composites. With respect to the neat polyester, the percentage increase in tensile strength of 0.5wt% INF filled nanocomposites was 57%. From the data of viscoelastic properties obtained, the amount of polyester chains confined at the cellulose nanofibrils were estimated and quantified. The volume fraction of the constrained region is highest for 0.5wt% INF. To understand the role of the constrained region in enhancing the mechanical properties of the nanocomposite, a constrained polymer model is proposed. The presence of INF increases the Tg of polyester matrix by 10°C. Spectroscopic studies revealed the presence of strong hydrogen bonding interaction between nanofibril surface and polyester matirx. Composites showed 73% decrease in water absorption indicating superior barrier properties of nanocelluose in the polyester matrix due to the network formation of the nanofibrils in the polyester matrix. © 2014 Elsevier B.V.

Bagchi J.,Inter-University Center for Astronomy and Astrophysics | Vivek M.,Inter-University Center for Astronomy and Astrophysics | Vikram V.,University of Pennsylvania | Hota A.,Center for Excellence in Basic science | And 6 more authors.
Astrophysical Journal | Year: 2014

The radio galaxy phenomenon is directly connected to mass-accreting, spinning supermassive black holes found in the active galactic nuclei. It is still unclear how the collimated jets of relativistic plasma on hundreds to thousands of kiloparsec scales form and why they are nearly always launched from the nuclei of bulge-dominated elliptical galaxies and not flat spirals. Here we present the discovery of the giant radio source J2345-0449 (z = 0.0755), a clear and extremely rare counterexample where relativistic jets are ejected from a luminous and massive spiral galaxy on a scale of ∼1.6 Mpc, the largest known so far. Extreme physical properties observed for this bulgeless spiral host, such as its high optical and infrared luminosity, large dynamical mass, rapid disk rotation, and episodic jet activity, are possibly the results of its unusual formation history, which has also assembled, via gas accretion from a disk, its central black hole of mass >2 × 108 M ⊙. The very high mid-IR luminosity of the galaxy suggests that it is actively forming stars and still building a massive disk. We argue that the launch of these powerful jets is facilitated by an advection-dominated, magnetized accretion flow at a low Eddington rate onto this unusually massive (for a bulgeless disk galaxy) and possibly fast spinning central black hole. Therefore, J2345-0449 is an extremely rare, unusual galactic system whose properties challenge the standard paradigms for black hole growth and the formation of relativistic jets in disk galaxies. Thus, it provides fundamental insight into accretion disk-relativistic jet coupling processes. © 2014. The American Astronomical Society. All rights reserved.

Aloysius Sabu N.,Nanoscience Research Center | Aloysius Sabu N.,Newman College | Priyanka K.P.,Nanoscience Research Center | Ganesh S.,Mangalore University | And 2 more authors.
Radiation Physics and Chemistry | Year: 2016

In this article we report the post irradiation effects in the structural and optical properties of nanocrystalline calcium tungstate synthesized by chemical precipitation and heat treatment. The samples were subjected to different doses of high-energy electron beam obtained from an 8 MeV Microton. Investigations using X-ray diffraction, scanning electron microscopy and Raman spectra confirmed changes in particle size and structural parameters. However, no phase change was detected for irradiated samples. The stretching/compressive strain caused by high energy electrons is responsible for the slight shift in the XRD peaks of irradiated samples. Modifications in the morphology of different samples were confirmed by scanning electron microscopy. Ultraviolet-visible absorption studies showed variations in the optical band gap (4.08-4.25 eV) upon electron-beam irradiation. New photoluminescence behaviour in electron beam irradiated nanocrystalline CaWO4 was evidenced. A blue shift of the PL peak with increase in intensity was observed in all the irradiated samples. © 2016 Elsevier Ltd.

Kanichukattu J.K.,Thomas College | Luke J.A.,Newman College
International Journal of Advanced Manufacturing Technology | Year: 2013

Process capability indices (PCIs) are extensively used statistical measures to assess process performance in manufacturing industry. In this paper, confidence intervals for the difference between PCIs for two processes are derived by the generalized pivotal quantity method. The indices Cpk, Cpmk, and Cpm are considered in this study. The performance of the proposed method is assessed using simulation study. The results are also illustrated using an example from industrial contexts. © Springer-Verlag London 2013.

Jose K.K.,Thomas College | Luke J.A.,Newman College
Quality and Reliability Engineering International | Year: 2013

Process capability indices such as Cp, Cpk, C pmk and Cpm are widely used in manufacturing industries to provide a quantitative measurement of the performance of the products. In this article, we derived generalized confidence intervals for the difference between process capability indices for two processes under one-way random effect model. Our study provides coverage probability close to the nominal value in almost all cases as shown via simulation. An example from industrial contexts is given to illustrate the results. Copyright © 2012 John Wiley & Sons, Ltd.

Chirayil C.J.,Newman College | Mathew L.,Newman College | Thomas S.,Mahatma Gandhi University
Reviews on Advanced Materials Science | Year: 2014

Lignocellulosic fibers have become the focus of intense interest in recent years. They have attracted the attention of scientists and technologies worldwide because of their tremendous advantages and now it is possible to isolate cellulose nanofibrils and nanowhiskers from various lignocellulosic wastes. Studies in this area have shown that both cellulose nanofibrils and nanowhiskers could be used as reinforcing fillers to improve mechanical and barrier properties of different types of polymer systems which include rubbers, thermoplastics and thermo-sets. This review paper provides an overview of recent progress made in the area of nanocellulose and nanowhiskers preparation from various natural fibers. A thorough review of the various techniques being currently used for the isolation of cellulose nanofibers and nanowhiskers has been presented. Finally, the emerging applications of these materials in various fields including nanocomposite preparation have been presented. © 2014 Advanced Study Center Co. Ltd.

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