Dynamic analyses and field observations on piles in Kolkata city

Chatterjee, Kaustav,Choudhury, Deepankar,Rao, Vansittee Dilli,Mukherjee, S.P. Techno-Press 2015 Geomechanics & engineering Vol.8 No.3

In the present case study, High Strain Dynamic Testing of piles is conducted at 3 different locations of Kolkata city of India. The raw field data acquired is analyzed using Pile Driving Analyzer (PDA) and CAPWAP (Case Pile Wave Analysis Programme) computer software and load settlement curves along with variation of force and velocity with time is obtained. A finite difference based numerical software FLAC3D has been used for simulating the field conditions by simulating similar soil-pile models for each case. The net pile displacement and ultimate pile capacity determined from the field tests and estimated by using numerical analyses are compared. It is seen that the ultimate capacity of the pile computed using FLAC3D differs from the field test results by around 9%, thereby indicating the efficiency of FLAC3D as reliable numerical software for analyzing pile foundations subjected to impact loading. Moreover, various parameters like top layers of cohesive soil varying from soft to stiff consistency, pile length, pile diameter, pile impedance and critical height of fall of the hammer have been found to influence both pile displacement and net pile capacity substantially. It may, therefore, be suggested to include the test in relevant IS code of practice.

Syntheses of Boron Nitride Nanotubes from Borazine and Decaborane Molecular Precursors by Catalytic Chemical Vapor Deposition with a Floating Nickel Catalyst

Chatterjee, Shahana,Kim, Myung Jong,Zakharov, Dmitri N.,Kim, Seung Min,Stach, Eric A.,Maruyama, Benji,Sneddon, Larry G. American Chemical Society 2012 Chemistry of materials Vol.24 No.15

<P>Multi- and double-walled boron nitride nanotubes (BNNTs) have been synthesized with the aid of a floating nickel catalyst via the catalytic chemical vapor deposition (CCVD) of either the amine-borane borazine (B<SUB>3</SUB>N<SUB>3</SUB>H<SUB>6</SUB>) or the polyhedral-borane decaborane (B<SUB>10</SUB>H<SUB>14</SUB>) molecular precursors in ammonia atmospheres. Both sets of BNNTs were crystalline with highly ordered structures. The BNNTs grown at 1200 °C from borazine were mainly double-walled, with lengths up to 0.2 μm and ∼2 nm diameters. The BNNTs grown at 1200–1300 °C from decaborane were double- and multiwalled, with the double-walled nanotubes having ∼2 nm inner diameters and the multiwalled nanotubes (∼10 walls) having ∼4–5 nm inner diameters and ∼12–14 nm outer diameters. BNNTs grown from decaborane at 1300 °C were longer, averaging ∼0.6 μm, whereas those grown at 1200 °C had average lengths of ∼0.2 μm. The BNNTs were characterized using scanning and transmission electron microscopies (SEM and TEM), and electron energy loss spectroscopy (EELS). The floating catalyst method provides a catalytic and potentially scalable route to BNNTs with low defect density from safe and commercially available precursor compounds.</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/cmatex/2012/cmatex.2012.24.issue-15/cm3006088/production/images/medium/cm-2012-006088_0009.gif'></P><P><A href='http://pubs.acs.org/doi/suppl/10.1021/cm3006088'>ACS Electronic Supporting Info</A></P>

Controlled Fluoroalkylation Reactions by Visible-Light Photoredox Catalysis

Chatterjee, Tanmay,Iqbal, Naeem,You, Youngmin,Cho, Eun Jin American Chemical Society 2016 Accounts of chemical research Vol. No.

<P>Owing to their unique biological, iihysical, and chemical properties, fluoroalkylated organic substances have attracted significant attention from researchers in a variety of disciplines. Fluoroalkylated compounds are considered particularly important in pharmaceutical chemistry because of their superior lipophilicity, binding selectivity, metabolic stability, and bioavailability to those of their nonfluoroalkylated analogues. We have developed various methods for the synthesis of fluoroalkylated substances that rely on the use of visible-light photoredox catalysis, a powerful preparative tool owing to, its environmental benignity and mechanistic versatility in promoting a large number of synthetically important reactions with high levels of selectivity. In this Account, we describe the results of our efforts, which have led to the development of visible-light photocatalytic methods for the introduction of a variety of fluoroalkyl groups (such as, CF3, CF2R, CH2CF3, C3F7, and C4F9) and arylthiofluoroalkyl groups (such as, CF2SPh, C2F4SAr, and C4F8SAr) to organic substances. In these studies, electron deficient carbon-centered fluoroalkyl radicals were successfully generated by the appropriate choice of fluoroalkyl source, photocatalyst, additives, and solvent. The redox potentials of the photocatalysts and the fluoroalkyl sources and the choice of sacrificial electron donor or acceptor as the additive affected the photocatalytic pathway, determining whether an oxidative or reductive quenching pathway was operative for the generation of key fluoroalkyl radicals. Notably, we have observed that additives significantly affect the efficiencies and selectivities of these reactions and can even change the outcome of the reaction by playing additional roles during its course. For instance, a tertiary amine as an additive in the reaction medium can act not only as a sacrificial electron donor in.photoredox catalysis but also as a hydrogen atom source, an elimination base for dehydrohalogenation of the intermediate, and also a Bronsted base for deprotonation. In the same context, the selection of solvent is also critical since it affects the rate and selectivity of reactions depending upon its polarity and reagent solubilizing ability and plays additional roles in the process, for example, as a hydrogen atom source. By clearly understanding the roles of additives and solvent, we designed several controlled fluoroalkylation reactions where different products were formed selectively from the same starting substrates. In addition, we could exploit one of the most important advantages of radical reactions, that is, the use of unactivated Jr-systems such as alkenes, alkynes, arenes, and heteroarenes as radical acceptors without prefunctionalization. Furthermore, fluoroalkylation processes under mild room temperature reaction conditions tolerate various functional groups and are therefore easily applicable to late-stage modifications of highly functionalized advanced intermediates.</P>

Enhanced mechanical strength of chitosan hydrogel beads by impregnation with carbon nanotubes

Chatterjee, S.,Lee, M.W.,Woo, S.H. Pergamon Press ; Elsevier Science Ltd 2009 Carbon Vol.47 No.12

Chitosan (CS) hydrogel beads were impregnated with carbon nanotubes (CNTs), and their mechanical strength, acid stability and adsorption capacity to the anionic dye, Congo red (CR), were investigated by comparing with a conventional reinforcing method of cross-linking with epichlorohydrin (ECH). CS/CNT hydrogel beads were manufactured by dispersing CNTs (0.01wt.%) with cetyltrimethylammonium bromide (CTAB) (0.05wt.%) into CS solution (1wt.%). Maximum endurable force at complete breakdown of CS hydrogel beads increased from 1.87 to 7.62N with incorporation of CNTs and its adsorption capacity increased from 178.32 to 423.34mgg<SUP>-1</SUP> for adsorption of CR.

Type 1 optimal $2^m$ fractional factorial plans with $n{\equiv}{\ell}$ (mod 8) runs, ${\ell}=1,2$

Chatterjee, Kashinath,Kolyva-Machera, Fotini,Chatzopoulos, Stavros A. 한국통계학회 2011 Journal of the Korean Statistical Society Vol.40 No.4

This paper considers the issue of optimality of fractional factorial experiments involving m factors each at two levels. The optimality criteria used here is the type 1 criteria, due to Cheng (1978), which include the D- and A-criteria. It is shown that if there exists an orthogonal array OA(n - ${\ell}$, m, 2, 3), ${\ell}=1,2$, then there exists an n-run type 1 optimal fractional factorial plan for a $2^m$ experiment under a model that includes the mean, all main effects and all two-factor interactions with a factor in common. These plans are obtained by adding any one run to an OA(n - 1,m, 2, 3) for $n{\equiv}1$ (mod 8) and two specific runs to an OA(n - 2, m, 2, 3) for $n{\equiv}2$ (mod 8).

HPV and Cervical Cancer Epidemiology - Current Status of HPV Vaccination in India

Chatterjee, Sharmila,Chattopadhyay, Amit,Samanta, Luna,Panigrahi, Pinaki Asian Pacific Journal of Cancer Prevention 2016 Asian Pacific journal of cancer prevention Vol.17 No.8

Cervical cancer (CaCx) is the second most fatal cancer contributing to 14% of cancers in Indian females, which account for 25.4% and 26.5% of the global burden of CaCx prevalence and mortality, respectively. Persistent infection with high-risk human papilloma virus (HPV- strains 16 and 18) is the most important risk factor for precursors of invasive CaCx. Comprehensive prevention strategies for CaCx should include screening and HPV vaccination. Three screening modalities for CaCx are cytology, visual inspection with acetic acid, and HPV testing. There is no Indian national policy on CaCx prevention, and screening of asymptomatic females against CaCx is practically non-existent. HPV vaccines can make a major breakthrough in the control of CaCx in India which has high disease load and no organized screening program. Despite the Indian Government's effort to introduce HPV vaccination in the National Immunization Program and bring down vaccine cost, challenges to implementing vaccination in India are strong such as: inadequate epidemiological evidence for disease prioritization, duration of vaccine use, parental attitudes, and vaccine acceptance. This paper reviews the current epidemiology of CaCx and HPV in India, and the current status of HPV vaccination in the country. This article stresses the need for more research in the Indian context, to evaluate interventions for CaCx and assess their applicability, success, scalability and sustainability within the constraints of the Indian health care system.

Selective Fluorogenic and Chromogenic Probe for Detection of Silver Ions and Silver Nanoparticles in Aqueous Media

Chatterjee, Amrita,Santra, Mithun,Won, Nayoun,Kim, Sungjee,Kim, Jae Kyung,Kim, Seung Bin,Ahn, Kyo Han American Chemical Society 2009 JOURNAL OF THE AMERICAN CHEMICAL SOCIETY - Vol.131 No.6

<P>A novel rhodamine-based fluorogenic and chromogenic probe for Ag(+) ions in aqueous media is developed, which can be also used for the detection of AgNPs. The sensing mechanism is based on irreversible tandem ring-opening and -forming processes promoted by Ag(+)-coordination to the iodide of the probe, which is accompanied by both color and turn-on type fluorescence changes. The probe shows remarkably high selectivity over other metal ions and detects silver ions up to 14 ppb.</P>

Visible-Light-Induced Synthesis of Carbazoles by in Situ Formation of Photosensitizing Intermediate

Chatterjee, Tanmay,Roh, Geum-bee,Shoaib, Mahbubul Alam,Suhl, Chang-Heon,Kim, Jun Soo,Cho, Cheon-Gyu,Cho, Eun Jin American Chemical Society 2017 ORGANIC LETTERS Vol.19 No.7

<P>A visible-light-induced synthesis of N-H carbazoles from easily accessible 2,2'-diaminobiaryls in the absence of any external photosensitizer is reported. The process only requires BuONO and natural resources, visible light, and molecular oxygen for the synthesis of N-H carbazoles. Experimental and computational studies support that the in situ formation of a visible-light-absorbing photosensitizing intermediate, benzocinnoline N-imide, is responsible for the activation of triplet molecular oxygen to singlet oxygen that, in turn, promotes the synthesis of carbazole.</P>

Impact of open pit coal mining on the forest landscape ecology using spatial metrics: a study of Barabani C.D. block, West Bengal

Chatterjee Soumen 대한공간정보학회 2021 Spatial Information Research Vol.29 No.5

Mining is an extractive activity that creates pits, scars and waste dump especially when operated on open cast basis that not only degrades the landscape structure but also have significant impact over its functioning. There is a general consensus about the role of forest as an important entity of landscape structure in maintaining the ecological balance which is under immense pressure by the various anthropogenic activities like growth of built up area by means of urban industrial growth and expansion of mining area. This study has been conducted with an objective to assess the ecological health of the forest landscape and to analyse the land use land cover change in Barabini C.D. block of West Bengal, Eastern India where hectares of forest land has been greatly modified by open pit coal mining. The study has employed two satellite images of 2000 and 2017 to assess the land use land cover and spatial metrics of the study area. Modification of land use land cover to a large extent has been reported during the specified time, for instance, forest cover and agricultural land decreased considerably; built up area and mining area has been increased to a great extent. Landscape matrices of class level and landscape level concerning with the surface, shape, edge character and spatial distribution has been calculated to analyzed the spatio temporal character of the landscape. Increase in the landscape level spatial metrics value indicative of the development of a complex landscape structure with shrinking vegetative cover. The result of class level indices also reported that, the forest land not only fragmented by the formation of open cast pit but also experienced huge spatial loss over the specified time. This phenomenal change of the landscape structure is a matter of serious environmental concern that needs immediate attention for the sustainability of the region.

AN IMPROVED ADDITIVE MODEL FOR RELIABILITY ANALYSIS OF SOFTWARE WITH MODULAR STRUCTURE

Chatterjee, S.,Nigam, S.,Singh, J.B.,Upadhyaya, L.N. The Korean Society for Computational and Applied M 2012 Journal of applied mathematics & informatics Vol.30 No.3

Most of the software reliability models are based on black box approach and these models consider the entire software system as a single unit. Present day software development process has changed a lot. In present scenario these models may not give better results. To overcome this problem an improved additive model has been proposed in this paper, to estimate the reliability of software with modular structure. Also the concept of imperfect debugging has been also considered. A maximum likelihood estimation technique has been used for estimating the model parameters. Comparison has been made with an existing model. ${\chi}^2$ goodness of fit has been used for model fitting. The proposed model has been validated using real data.