Vitellogenin Induction and Histo-metabolic Changes Following Exposure of Cyprinus carpio to Methyl Paraben

Barse, A.V.,Chakrabarti, T.,Ghosh, T.K.,Pal, A.K.,Kumar, Neeraj,Raman, R.P.,Jadhao, S.B. Asian Australasian Association of Animal Productio 2010 Animal Bioscience Vol.23 No.12

Methyl paraben (MP), which is used as a preservative in pharmaceutical and cosmetic (shampoo) products, foods and beverages, enters into the aquatic environment and can pose a potential fish health hazard. In this experiment, effects of MP were evaluated in adult male common carp (Cyprinus carpio) by exposing them to fractions (1/$143^{rd}$ to 1/29th) of the $LC_{50}$ dose with every change of water for 28 days. Vitellogenin induction, metabolic enzymes, somatic indices and bioaccumulation were studied at weekly intervals. The $96^{th}$ h $LC_{50}$ of MP in fingerlings was 120 mg/L. Compared to the control, except for increases (p<0.01) in alkaline phosphatase (EC 3.1.3.1), alanine aminotransferase (EC 2.6.1.2) and liver size, there were decreases (p<0.01) in activity of acid phosphatase (EC 3.1.3.2), aspartate aminotransferase (EC 2.6.1.1), and testiculosomatic index following exposure to any dose of MP. Vitellogenin induction was significantly higher (p<0.01) in exposed than unexposed (control) fish. The bioaccumulation of MP in testis, liver, brain, gills and muscle tissues of fish increased significantly (p<0.01) with increase of dose from 0.84 ppm to 1.68 ppm. Dose and duration of exposure (p<0.01) indicated that an exposure period of 1 to 2 weeks was sufficient to cause changes in the quantifiable parameters studied. Fish exposed to 4.2 ppm MP became lethargic after the $26^{th}$ d. Histologically, degeneration, vacuolization and focal necrotic changes in liver and fibrosis-like changes in testicular tissue were noted.

Thickness Dependent Study of RF Sputtered ZnO Thin Films for Optoelectronic Device Applications

Shashikant Sharma,C. Periasamy,P. Chakrabarti 대한금속·재료학회 2015 ELECTRONIC MATERIALS LETTERS Vol.11 No.6

This work reports thickness dependent structural and optical studies of ZnO thin films grown over p-type silicon (Si) and glass substrates using RF sputtering technique. The effect of variation of thickness on different microstructural and surface morphological parameters such as lattice constant, grain size, dislocation density, residual stress, lattice strain and surface roughness have been studied. All samples under study exhibited a hexagonal wurtzite structure with preferential growth along the c-axis perpendicular to the surface. It has been observed that structural disorder, stress and strain in the film reduces and as a result the crystalline quality of deposited ZnO thin films improves with increasing thickness. Optical characterization of deposited films has been done using UVvisible spectrophotometer, ellipsometer and photoluminescence spectroscope. Transmittance spectra of all ZnO thin film samples (190 - 342 nm) have exhibit a high transmittance over 85% in the visible region, and refractive index was found to vary between 0.85 - 3.1 in UV-Visible wavelength region (300 - 800 nm). The optical bandgap recorded a marginal increase from 3.22 eV to 3.26 eV by varying the thickness from 190 - 342 nm. Effect of film thickness on other optical parameters such as absorbance, reflectance, urbach energy, dielectric constant and photoluminescence has also been analyzed and reported.

Ferric ions accumulate in the walls of metabolically inactivating Saccharomyces cerevisiae cells and are reductively mobilized during reactivation

Wofford, J.,Park, J.,McCormick, S.,Chakrabarti, M.,Lindahl, P. ROYAL SOCIETY OF CHEMISTRY 2016 Metallomics Vol.8 No.7

<P>Mossbauer and EPR spectra of fermenting yeast cells before and after cell wall (CW) digestion revealed that CWs accumulated iron as cells transitioned from exponential to post-exponential growth. Most CW iron was mononuclear nonheme high-spin (NHHS) Fe-III, some was diamagnetic and some was superparamagnetic. A significant portion of CW Fe was removable by EDTA. Simulations using an ordinary-differential-equations-based model suggested that cells accumulate Fe as they become metabolically inactive. When dormant Fe-loaded cells were metabolically reactivated in Fe-deficient bathophenanthroline disulfonate (BPS)-treated medium, they grew using Fe that had been mobilized from their CWs AND using trace amounts of Fe in the Fe-deficient medium. When grown in Fe-deficient medium, Fe-starved cells contained the lowest cellular Fe concentrations reported for a eukaryotic cell. During metabolic reactivation of Fe-loaded dormant cells, Fe-III ions in the CWs of these cells were mobilized by reduction to Fe-II, followed by release from the CW and reimport into the cell. BPS short-circuited this process by chelating mobilized and released Fe-II ions before reimport; the resulting Fe-II(BPS) 3 complex adsorbed on the cell surface. NHHS Fe-II ions appeared transiently during mobilization, suggesting that these ions were intermediates in this process. In the presence of chelators and at high pH, metabolically inactive cells leached CW Fe; this phenomenon probably differs from metabolic mobilization. The iron regulon, as reported by Fet3p levels, was not expressed during post-exponential conditions; Fet3p was maximally expressed in exponentially growing cells. Decreased expression of the iron regulon and metabolic decline combine to promote CW Fe accumulation.</P>

High-Spin Ferric Ions in <i>Saccharomyces cerevisiae</i> Vacuoles Are Reduced to the Ferrous State during Adenine-Precursor Detoxification

Park, Jinkyu,McCormick, Sean P.,Cockrell, Allison L.,Chakrabarti, Mrinmoy,Lindahl, Paul A. American Chemical Society 2014 Biochemistry Vol.53 No.24

<P/><P>The majority of Fe in Fe-replete yeast cells is located in vacuoles. These acidic organelles store Fe for use under Fe-deficient conditions and they sequester it from other parts of the cell to avoid Fe-associated toxicity. Vacuolar Fe is predominantly in the form of one or more magnetically isolated nonheme high-spin (NHHS) Fe<SUP>III</SUP> complexes with polyphosphate-related ligands. Some Fe<SUP>III</SUP> oxyhydroxide nanoparticles may also be present in these organelles, perhaps in equilibrium with the NHHS Fe<SUP>III</SUP>. Little is known regarding the chemical properties of vacuolar Fe. When grown on adenine-deficient medium (A↓), ADE2Δ strains of yeast such as W303 produce a toxic intermediate in the adenine biosynthetic pathway. This intermediate is conjugated with glutathione and shuttled into the vacuole for detoxification. The iron content of A↓ W303 cells was determined by Mössbauer and EPR spectroscopies. As they transitioned from exponential growth to stationary state, A↓ cells (supplemented with 40 μM Fe<SUP>III</SUP> citrate) accumulated two major NHHS Fe<SUP>II</SUP> species as the vacuolar NHHS Fe<SUP>III</SUP> species declined. This is evidence that vacuoles in A↓ cells are more reducing than those in adenine-sufficient cells. A↓ cells suffered less oxidative stress despite the abundance of NHHS Fe<SUP>II</SUP> complexes; such species typically promote Fenton chemistry. Most Fe in cells grown for 5 days with extra yeast-nitrogen-base, amino acids and bases in minimal medium was HS Fe<SUP>III</SUP> with insignificant amounts of nanoparticles. The vacuoles of these cells might be more acidic than normal and can accommodate high concentrations of HS Fe<SUP>III</SUP> species. Glucose levels and rapamycin (affecting the TOR system) affected cellular Fe content. This study illustrates the sensitivity of cellular Fe to changes in metabolism, redox state and pH. Such effects broaden our understanding of how Fe and overall cellular metabolism are integrated.</P>

Positron annihilation spectroscopy of polyacrylonitrile-based carbon fibers embedded with multi-wall carbon nanotubes

Chakrabarti, K.,Nambissan, P.M.G.,Mukherjee, C.D.,Bardhan, K.K.,Kim, C.,Yang, K.S. Elsevier 2006 Carbon Vol.44 No.5

<P><B>Abstract</B></P><P>Polyacrylonitrile (PAN)-based carbon fibers, embedded with multi-wall carbon nanotubes (MWCNT) in different concentrations, have been prepared by an electrospinning technique and investigated using scanning electron microscopy, Raman, and positron annihilation spectroscopy. An analysis of the positron lifetime and Doppler broadened spectral line shape has been made. Positron lifetime spectra for all the samples give best fit for three distinct lifetime components. Raman data has been used to estimate the sp<SUP>2</SUP> mole fraction in the fiber. It is found that the gradual changes incorporated in the fiber due to the addition of MWCNTs are reflected as well defined changes in the positron lifetime and the <I>S</I> parameter of the Doppler broadened spectral line. Annihilation parameters are discussed from the point of view of formation of distinct positron trapping sites in the form of vacancy type defects at the interfaces of MWCNTs and the PAN matrix, and their variations in concentration due to different amount of MWCNTs added.</P>

Speciation of iron in mouse liver during development, iron deficiency, IRP2 deletion and inflammatory hepatitis

Chakrabarti, M.,Cockrell, A.,Park, J.,McCormick, S.,Lindahl, L.,Lindahl, P. ROYAL SOCIETY OF CHEMISTRY 2015 Metallomics Vol.7 No.1

A Review on Welding Residual Stress Measurement by Hole Drilling Technique and its Importance

R. Chakrabarti,P. Biswas,S. C. Saha 대한용접·접합학회 2018 대한용접·접합학회지 Vol.36 No.4

Welding residual stress is considered as one of the most responsible factors by the experts for premature failure of the in-service welded structures. Between tensile residual stress and compressive residual stress, while the former type is found to have detrimental effect on the welded part, compressive stress may adhere to some benefits in many cases. It is, therefore, very important to evaluate the welding residual stress in a welded component properly so that suitable measures can be adopted to get the optimized service life of the fabricated structure. The measurement techniques of welding residual stress have been classified into different categories, significantly in destructive and non-destructive in nature. The hole drilling technique is one of the destructive methodologies to measure the welding residual stress using strain gauges which is standardized by ASTM E-837 and frequently used in the applied field. In this review paper, an effort has been given to understand the fundamentals of the hole drilling method based on extensive literatures’ study which reflects the chronological developments of this technique in the field of stress measurement. This paper, further, describes the influence of different operational parameters associated with the hole drilling technique on the outcome of the process.

Analysis of Surface Potential and Electric Field for Fully Depleted Graded Channel Dual-Material-Double-Gate MOSFET through Modeling and Simulation

Himeli Chakrabarti,Reshmi Maity,Tijana Kevkić,Vladica Stojanović,N. P. Maity 한국전기전자재료학회 2021 Transactions on Electrical and Electronic Material Vol.22 No.4

This article is about an elaborative description of two dimensional investigative mathematical structure of fully depleted graded channel (GC) dual-material-double-gate (DMDG) silicon-on-insulator metal–oxide–semiconductor-fi eld-eff ecttransistor (SOI MOSFET). The surface potential contours in addition with electric field variation throughout the channel establish reduction of short-channel-effects (SCEs). To get better operational analysis, some new characteristics such as temperature effect and interface charge eff ects have been incorporated in the model. In this representation we also incorporate the consequences of high-k dielectric medium HfO2 instead of SiO2 and have made a comparison with the effect in various frameworks. In the GC DMDG composition, the surface potential as well as electric field throughout the channel shows close to step function variations which help to defeat the hot carrier along with drain-induced-barrier-lowering (DIBL) effects. As an outcome, the structure shows that the surface potential profi le increases by using GC DMDG structure over DMDG. All these outcomes of the proposed analytical representation have been compared by TCAD simulation consequence. Very good conformity is observed between them.

Influence of Scanning and Building Strategies on the Deformation Behavior of Additively Manufactured AlSi10Mg: CPFEM and Finite Element Studies

Aniket Chakrabarty,Pritam Chakraborty,Roopam Jain,Vivek Kr. Sahu,N. P. Gurao,H. N. Bar,Niloy Khutia 대한금속·재료학회 2023 METALS AND MATERIALS International Vol.29 No.10

A novel computational framework has been presented in this work for understanding the mechanical deformation behaviorin additively manufactured parts. AlSi10Mg parts were additively manufactured and investigated for effects on microstructuredue to changes in process parameters. The morphological characteristics of the printed parts were assessed, and 2Dstatistically equivalent representative volume elements (SERVEs) were created and analyzed for deformation under tensioncomputationally with crystal plasticity finite element method (CPFEM) with a combined MATLAB and ABAQUS interactiveframework. For assessing the CPFEM parameters, an interactive ABAQUS and MATLAB environment was implementedusing MATLAB’s genetic algorithm (GA) toolbox. Various results like von Mises stress distribution, maximum in-planestress distribution, and L2-norm of Green Lagrange’s strain were compared, and it was found that the vulnerability of thestructures is related to the change in process or build parameters. CPFEM analyses on 3D microstructures generated throughDREAM. 3D further confirmed the validity of results for CPFEM in 2D. The developed 2D framework also predicted thetexture that correlated well with the tension test findings. Parallely, a finite element framework was developed to study thelocalization effects on AM specimens due to the presence of pores. This work has reported two separate viewpoints in termsof porosity and microstructure.

Electrical and optical characterization of ZnO based nano and large area Schottky contacts

C. Periasamy,P. Chakrabarti 한국물리학회 2011 Current Applied Physics Vol.11 No.4

Nanocrystalline ZnO thin films have been grown on glass substrates by thermal evaporation technique. The structural, morphological and optical properties of the thin film were investigated using X-ray diffraction, atomic force microscopy (AFM) and UV measurements respectively. The study revealed that ZnO nanoneedles consist of typical single crystalline ZnO with perfect needle shape and small surface roughness. The grown ZnO thin film was subsequently used to fabricate a metal―semiconductor―metal (MSM) ZnO photodiode with palladium (Pd) contact electrodes. The detector was successfully tested using the UV source operating at λ = 365 nm. The photoresponsivity of the detector is estimated to be 0.14 A/W. The device is expected to be used as a sensitive UV detector.