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Bhaumik, Atanu,Peterson, Gregory I.,Kang, Cheol,Choi, Tae-Lim American Chemical Society 2019 JOURNAL OF THE AMERICAN CHEMICAL SOCIETY - Vol.141 No.31
<P>Monomers derived from glucose and galactose, which contain an endocyclic alkene (in the sugar ring) and a terminal alkyne, underwent a cascade polymerization to prepare new polymers with the ring-opened sugar incorporated into the polymer backbone. Polymerizations were well-controlled, as demonstrated by a linear increase in molecular weight with monomer-to-initiator ratio and generally narrow molecular weight dispersity values. The living nature of the polymerization was supported by the preparation of a block copolymer from two different sugar-based monomers. The resulting polymers were also fully degradable. They underwent fast and complete depolymerization to small molecules under acidic conditions.</P> [FIG OMISSION]</BR>
Shankar Bhaumik,A. Kumaraswamy,S. Guruprasad,P. Bhandari 대한기계학회 2015 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.29 No.11
Contact based FE simulations have been carried out to estimate the contact pressure distribution at seal/rod interface at sealed oil pressuresof 10, 20 and 30 MPa and constant rod velocity of 0.12 m/s. Oil film thickness at the interface was then computed analytically atvarious combinations of oil pressures and rod velocities. Seal contact pressure and oil film thickness data along with surface roughness,intermolecular interaction between seal/rod interfaces has been perused to estimate the friction in Nitrile-Butadiene Rubber (NBR) rectangularhydraulic rod seals using theoretical models such as Inverse hydrodynamic lubrication (IHL), Greenwood-Williamson (GW)and Wassink’s models. The friction at seal/rod interface was also measured experimentally using a specially designed test rig. The comparisonof theoretical and experimental data revealed that, friction computed from GW and Wassink’s models had good agreement withthe experimental results.
Minimizing axial dispersion in narrow packed column using superhydrophobic wall
Soubhik Kumar Bhaumik,Tamoghna Saha,Shashi Kumar 한국화학공학회 2016 Korean Journal of Chemical Engineering Vol.33 No.12
The scope of minimizing dispersion in narrow packed column using superhydrophobic (SH) wall is assessed experimentally with implications in analytical techniques such as liquid chromatography. The study includes devising a packed column (7-19 mm) with lotus leaf pasted on the inner wall and establishing a gravity driven flow through it. The flow dispersion is characterized based on the residence time distribution study of the column. The results are compared against similar flow through smooth packed column. Experimental results reveal the influence of two factors: column diameter as well as the wall features, superhydrophobic or smooth. For similar surface features, the axial dispersion reduces with decrease in column diameter due to the increase in voidage, which leads to plug flow. For the same diameter, between smooth and superhydrophobic, effects of slip in the latter reduce the dispersion significantly. Thus, the introduction of superhydrophobic narrow columns can play a crucial role in minimizing dispersion in analytical techniques.
Katlego Zebedius Setshedi,Madhumita Bhaumik,Maurice Stephen Onyango,Arjun Maity 한국공업화학회 2014 Journal of Industrial and Engineering Chemistry Vol.20 No.4
Fixed bed adsorption column studies were carried out to assess the breakthrough performance of the polypyrrole-organically modified montmorillonite clay (PPy-OMMT NC) for removal of toxic Cr(VI) from water. The effects of bed mass, initial Cr(VI) concentration and flow rate on the bed performance were evaluated and a notable bed performance (3.2 L treated water) was achieved at high bed mass, low inlet Cr(VI) concentration and flow rate. Experimental data agreed well with the Thomas and Yoon–Nelson model. Based on performance data, it can be concluded that the PPy-OMMT NC is a competitive sorption media for Cr(VI) removal from aqueous environments.
Higher Degree Cubature Quadrature Kalman Filter
Abhinoy Kumar Singh,Shovan Bhaumik 제어·로봇·시스템학회 2015 International Journal of Control, Automation, and Vol.13 No.5
In this paper, an algorithm has been developed to solve the nonlinear estimation problems. The intractable integrals, appeared during the estimation, have been approximately evaluated using any arbitrary but odd degree spherical cubature and higher order Gauss-Laguerre quadrature rule. The pro-posed method is termed as higher degree cubature quadrature Kalman filter (HDCQKF). With the help of two examples it has been shown that the accuracy of the proposed filter is higher compared to the cubature Kalman filter (CKF), the cubature quadrature Kalman filter (CQKF), and the higher degree cubature Kalman filter (HDCKF). The proposed method is a generalization of all existing cubature fil-ters and under certain simplifications it merges with them.
Piao, Shang Hao,Bhaumik, Madhumita,Maity, Arjun,Choi, Hyoung Jin The Royal Society of Chemistry 2015 Journal of Materials Chemistry C Vol.3 No.8
<P>Fe<SUP>0</SUP>nanoparticle-supported polyaniline (PANI) composite nanofibers were prepared as an additive for carbonyl iron (CI)-based magnetorheological (MR) fluids to improve the MR properties and dispersion stability. A simple chemical strategy was adopted to synthesize the PANI/Fe<SUP>0</SUP>composite nanofibers. The synthesis method was based on the initial fabrication of interconnected PANI nanofibers by a rapidly mixed polymerization process using ferric chloride (FeCl3) as the oxidant and the subsequent reductive support of Fe<SUP>0</SUP>nanoparticles onto the PANI nanofiber matrix using the polymerization by-products as a metal precursor. X-ray diffraction, Fourier transform infrared spectroscopy, and X-ray photoelectron spectroscopy showed that the fabricated nanofibers were composed of PANI and Fe<SUP>0</SUP>. Scanning and transmission electron microscopy imaging confirmed that the PANI/Fe<SUP>0</SUP>composite nanofibers were 80-150 nm in diameter with an interconnected matrix. The MR fluid with the PANI/Fe<SUP>0</SUP>composite nanofibers dispersed in mineral oil under an external magnetic field showed enhanced MR properties compared to that without an additive. Turbiscan data also confirmed the improved sedimentation properties of the MR fluid with an additive.</P>
Patra, A.,Kundu, S.,Bhaumik, A.,Kim, D. Royal Society of Chemistry 2016 Nanoscale Vol.8 No.1
<P>We have developed a new green chemical approach for the shape-controlled synthesis of single-crystalline hematite nanocrystals in aqueous medium. FESEM, HRTEM and SAED techniques were used to determine the morphology and crystallographic orientations of each nanocrystal and its exposed facets. PXRD and HRTEM techniques revealed that the nanocrystals are single crystalline in nature; twins and stacking faults were not detected in these nanocrystals. The structural, vibrational, and electronic spectra of these nanocrystals were highly dependent on their shape. Different shaped hematite nanocrystals with distinct crystallographic planes have been synthesized under similar reaction conditions, which can be desired as a model for the purpose of properties comparison with the nanocrystals prepared under different reaction conditions. Here we investigated the photocatalytic performance of these different shaped-nanocrystals for methyl orange degradation in the presence of white light (lambda > 420 nm). In this study, we found that the density of surface Fe3+ ions in particular facets was the key factor for the photocatalytic activity and was higher on the bitruncated-dodecahedron shape nanocrystals by coexposed {104}, {100} and {001} facets, attributing to higher catalytic activity. The catalytic activity of different exposed facet nanocrystals were as follows: {104} + {100} + {001} (bitruncated-dodecahedron) > {101} + {001} (bitruncated-octahedron) > {001} + {110} (nanorods) > {012} (nanocuboid) which provided the direct evidence of exposed facet-driven photocatalytic activity. The nanocrystals were easily recoverable using an external magnet and reused at least six times without significant loss of its catalytic activity.</P>