Site preference of NH₃-adsorption on Co, Pt and CoPt surfaces: the role of charge transfer, magnetism and strain

Bhattacharjee, S.,Gupta, K.,Jung, N.,Yoo, S. J.,Waghmare, U. V.,Lee, S. C. The Royal Society of Chemistry 2015 Physical chemistry chemical physics Vol.17 No.14

<P>Oxidation of Co at the surface poses a major problem in the cyclable use of CoPt, a cost-effective catalyst for proton exchange membrane fuel cells. This can be alleviated by attaching a ligand selectively to Co-sites to stop its oxidation without compromising the catalytic activity. Here, we present a comparative analysis of adsorption of NH<SUB>3</SUB> on the (0001) surface of Co in the HCP structure and (111) surfaces of Pt and CoPt alloy in the FCC structure, using first-principles density functional theoretical calculations. While NH<SUB>3</SUB> binds more strongly with the Pt surface than with the Co surface, we find that its binding with the Co atom is stronger than that with the Pt atom on the surface of the CoPt alloy. Our analysis of the charge density and electronic structure shows how this originates from (a) the electron transfer from the minority spin d-band of Co to Pt, and (b) shift in the energy of d-bands and the magnetic moments of Co atoms on the surface of the CoPt alloy relative to those on the (0001) surface of Co. Hybridization of the d-states of Co in CoPt with p<SUB><I>z</I></SUB> states of N in NH<SUB>3</SUB> used to stop Co oxidation also results in improving the charge transfer from Co to Pt that is relevant to the catalytic activity of CoPt. We finally present the analysis of how the interaction of NH<SUB>3</SUB> with the CoPt surface can be tuned with strain.</P> <P>Graphic Abstract</P><P>Oxidation of Co at the surface poses a major problem in the cyclable use of CoPt, a cost-effective catalyst for proton exchange membrane fuel cells. <IMG SRC='http://pubs.rsc.org/services/images/RSCpubs.ePlatform.Service.FreeContent.ImageService.svc/ImageService/image/GA?id=c4cp05557h'> </P>

Fundamentals of Particle Fouling in Membrane Processes

Bhattacharjee Subir,Hong Seungkwan The Membrane Society of Korea 2005 Korean Membrane Journal Vol.7 No.1

The permeate flux decline due to membrane fouling can be addressed using a variety of theoretical stand-points. Judicious selection of an appropriate theory is a key toward successful prediction of the permeate flux. The essential criterion f3r such a decision appears to be a detailed characterization of the feed solution and membrane properties. Modem theories are capable of accurately predicting several properties of colloidal systems that are important in membrane separation processes from fundamental information pertaining to the particle size, charge, and solution ionic strength. Based on such information, it is relatively straight-forward to determine the properties of the concentrated colloidal dispersion in a polarized layer or the cake layer properties. Incorporation of such information in the framework of the standard theories of membrane filtration, namely, the convective diffusion equation coupled with an appropriate permeate transport model, can lead to reasonably accurate prediction of the permeate flux due to colloidal fouling. The schematic of the essential approach has been delineated in Figure 5. The modern approaches based on appropriate cell models appear to predict the permeate flux behavior in crossflow membrane filtration processes quite accurately without invoking novel theoretical descriptions of particle back transport mechanisms or depending on adjust-able parameters. Such agreements have been observed for a wide range of particle size ranging from small proteins like BSA (diameter ${\~}$6 nm) to latex suspensions (diameter ${\~}1\;{\mu}m$). There we, however, several areas that need further exploration. Some of these include: 1) A clear mechanistic description of the cake formation mechanisms that clearly identifies the disorder to order transition point in different colloidal systems. 2) Determining the structure of a cake layer based on the interparticle and hydrodynamic interactions instead of assuming a fixed geometrical structure on the basis of cell models. 3) Performing well controlled experiments where the cake deposition mechanism can be observed for small colloidal particles (< $1\;{\mu}m$). 4) A clear mechanistic description of the critical operating conditions (for instance, critical pressure) which can minimize the propensity of colloidal membrane fluting. 5) Developing theoretical approaches to account for polydisperse systems that can render the models capable of handing realistic feed solutions typically encountered in diverse applications of membrane filtration.

Kinetics of Oxidation of Nitrotoluenes by Acidic Hexacyanoferrate (Ⅲ)

Bhattacharjee, A. K.,Mahanti, M. K. Korean Chemical Society 1983 Bulletin of the Korean Chemical Society Vol.4 No.3

The reaction of hexacyanoferrate (Ⅲ) with nitrotoluenes in aqueous acetic acid containing perchloric acid(1.0 M) at $50^{\circ}C$ gave the corresponding aldehyde as the major product. The order with respect to each of the reactants ― substrate, oxidant and acid ― was found to be unity. The Hammett plot yielded a ${\sigma}^+$ value of -1.30, and the kinetic isotope effect gave a $k_H/k_D$ value of 6.2. The pathway for the conversion of the nitrotoluenes to the products has been mechanistically visualized as proceeding through the benzylic radical intermediate, formed in the rate determining step of the reaction.

High strength and formable Mg-6.2Zn-0.5Zr-0.2Ca alloy sheet processed by twin roll casting

Bhattacharjee, T.,Suh, B.C.,Sasaki, T.T.,Ohkubo, T.,Kim, N.J.,Hono, K. Elsevier Sequoia 2014 Materials science & engineering. properties, micro Vol.609 No.-

Twin roll cast and hot rolled Mg-6.2wt%Zn alloys microalloyed with Zr, Ca, and Ag show tensile yield strength exceeding 300MPa in the T6 (peak-aged) condition with reasonable formability in the T4 condition. The addition of Zr and Ca plays a critical role in the development of weak textured recrystallized microstructure in Mg-6.2wt%Zn alloys so Mg-6.2Zn-0.5Zr-0.2Ca (wt%) alloy shows equivalent mechanical properties with Mg-6.2Zn-0.5Zr-0.2Ca-0.4Ag (wt%) alloy even without expensive Ag.

Chemogenomics Profiling of Drug Targets of Peptidoglycan Biosynthesis Pathway in Leptospira interrogans by Virtual Screening Approaches

( Bhattacharjee Biplab ),( Rose Mary Simon ),( Chaithra Gangadharaiah ),( Prashantha Karunakar ) 한국미생물 · 생명공학회 2013 Journal of microbiology and biotechnology Vol.23 No.6

Leptospirosis is a worldwide zoonosis of global concern caused by Leptospira interrogans. The availability of ligand libraries has facilitated the search for novel drug targets using chemogenomics approaches, compared with the traditional method of drug discovery, which is time consuming and yields few leads with little intracellular information for guiding target selection. Recent subtractive genomics studies have revealed the putative drug targets in peptidoglycan biosynthesis pathways in Leptospira interrogans. Aligand library for the murD ligase enzyme in the peptidoglycan pathway has also been identified. Our approach in this research involves screening of the pre-existing ligand library of murD with related protein family members in the putative drug target assembly in the peptidoglycan biosynthesis pathway. A chemogenomics approach has been implemented here, which involves screening of known ligands of a protein family having analogous domain architecture for identification of leads for existing druggable protein family members. By means of this approach, one murC and one murF inhibitor were identified, providing a platform for developing an antileptospirosis drug targeting the peptidoglycan biosynthesis pathway. Given that the peptidoglycan biosynthesis pathway is exclusive to bacteria, the in silico identified mur ligase inhibitors are expected to be broad-spectrum Gram-negative inhibitors if synthesized and tested in in vitro and in vivo assays.

Multichannel Convolution Neural Network Classification for the Detection of Histological Pattern in Prostate Biopsy Images

Bhattacharjee, Subrata,Prakash, Deekshitha,Kim, Cho-Hee,Choi, Heung-Kook Korea Multimedia Society 2020 멀티미디어학회논문지 Vol.23 No.12

The analysis of digital microscopy images plays a vital role in computer-aided diagnosis (CAD) and prognosis. The main purpose of this paper is to develop a machine learning technique to predict the histological grades in prostate biopsy. To perform a multiclass classification, an AI-based deep learning algorithm, a multichannel convolutional neural network (MCCNN) was developed by connecting layers with artificial neurons inspired by the human brain system. The histological grades that were used for the analysis are benign, grade 3, grade 4, and grade 5. The proposed approach aims to classify multiple patterns of images extracted from the whole slide image (WSI) of a prostate biopsy based on the Gleason grading system. The Multichannel Convolution Neural Network (MCCNN) model takes three input channels (Red, Green, and Blue) to extract the computational features from each channel and concatenate them for multiclass classification. Stain normalization was carried out for each histological grade to standardize the intensity and contrast level in the image. The proposed model has been trained, validated, and tested with the histopathological images and has achieved an average accuracy of 96.4%, 94.6%, and 95.1%, respectively.

Potential of inherent RGD containing silk fibroin-poly (Є-caprolactone) nanofibrous matrix for bone tissue engineering

Bhattacharjee, Promita,Kundu, Banani,Naskar, Deboki,Kim, Hae-Won,Bhattacharya, Debasis,Maiti, T. K.,Kundu, S. C. Springer 2016 Cell and tissue research Vol. No.

<P>The current study deals with the fabrication and characterization of blended nanofibrous scaffolds of tropical tasar silk fibroin of Antheraea mylitta and poly (D'-caprolactone) to act as an ideal scaffold for bone regeneration. The use of poly (D'-caprolactone) in osteogenesis is well-recognized. At the same time, the osteoconductive nature of the non-mulberry tasar fibroin is also established due to its internal integrin binding peptide RGD (Arg-Gly-Asp) sequences, which enhance cellular interaction and proliferation. Considering that the materials have the required and favorable properties, the blends are formed using an equal volume ratio of fibroin (2 and 4 wt%) and poly (D'-caprolactone) solution (10 wt%) to fabricate nanofibers. The nanofibers possess an average diameter of 152 +/- 18 nm (2 % fibroin/PCL) and 175 +/- 15 nm (4 % fibroin/PCL). The results of Fourier transform infrared spectroscopy substantiates the preservation of the secondary structure of the fibroin in the blends indicating the structural stability of the neo-matrix. With an increase in the fibroin percentage, the hydrophobicity and thermal stability of the matrices as measured from melting temperature T-m (using DSC) decrease, while the mechanical strength is improved. The blended nanofibrous scaffolds are biodegradable, and support the viability and proliferation of human osteoblast-like cells as observed through scanning electron and confocal microscopes. Alkaline phosphatase assay indicates the cell proliferation and the generation of the neo-bone matrix. Taken together, these findings illustrate that the silk-poly (D'-caprolactone) blended nanofibrous scaffolds have an excellent prospect as scaffolding material in bone tissue engineering.</P>

Zeolitic Imidazolate Frameworks: Synthesis, Functionalization, and Catalytic/Adsorption Applications

Bhattacharjee, S.,Jang, M. S.,Kwon, H. J.,Ahn, W. S. Springer Science + Business Media 2014 CATALYSIS SURVEYS FROM ASIA Vol.18 No.4

Metal–Organic Frameworks for Catalysis

Bhattacharjee, S.,Lee, Y. R.,Puthiaraj, P.,Cho, S. M.,Ahn, W. S. Springer Science + Business Media 2015 CATALYSIS SURVEYS FROM ASIA Vol.19 No.4

Identification of Proapoptopic, Anti-Inflammatory, Anti-Proliferative, Anti-Invasive and Anti-Angiogenic Targets of Essential Oils in Cardamom by Dual Reverse Virtual Screening and Binding Pose Analysis

Bhattacharjee, Biplab,Chatterjee, Jhinuk Asian Pacific Journal of Cancer Prevention 2013 Asian Pacific journal of cancer prevention Vol.14 No.6

Background: Cardamom (Elettaria cardamom), also known as "Queen of Spices", has been traditionally used as a culinary ingredient due to its pleasant aroma and taste. In addition to this role, studies on cardamom have demonstrated cancer chemopreventive potential in in vitro and in vivo systems. Nevertheless, the precise poly-pharmacological nature of naturally occurring chemo-preventive compounds in cardamom has still not been fully demystified. Methods:In this study, an effort has been made to identify the proapoptopic, anti-inflammatory, anti-proliferative, anti-invasive and anti-angiogenic targets of Cardamom's bioactive principles (eucalyptol, alpha-pinene, beta-pinene, d-limonene and geraniol) by employing a dual reverse virtual screening protocol. Experimentally proven target information of the bioactive principles was annotated from bioassay databases and compared with the virtually screened set of targets to evaluate the reliability of the computational identification. To study the molecular interaction pattern of the anti-tumor action, molecular docking simulation was performed with Auto Dock Pyrx. Interaction studies of binding pose of eucalyptol with Caspase 3 were conducted to obtain an insight into the interacting amino acids and their inter-molecular bondings. Results:A prioritized list of target proteins associated with multiple forms of cancer and ranked by their Fit Score (Pharm Mapper) and descending 3D score (Reverse Screen 3D) were obtained from the two independent inverse screening platforms. Molecular docking studies exploring the bioactive principle targeted action revealed that H- bonds and electrostatic interactions forms the chief contributing factor in inter-molecular interactions associated with anti-tumor activity. Eucalyptol binds to the Caspase 3 with a specific framework that is well-suited for nucleophilic attacks by polar residues inside the Caspase 3 catalytic site. Conclusion:This study revealed vital information about the poly-pharmacological anti-tumor mode-of-action of essential oils in cardamom. In addition, a probabilistic set of anti-tumor targets for cardamom was generated, which can be further confirmed by in vivo and in vitro experiments.