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Excess Diffusion of a Driven Colloidal Particle in a Convection Array

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Chinese Physics Letters 2021年第4期38卷 17-21页

作者： Qingqing Yin Yunyun Li Fabio Marchesoni Debajyoti debnath Pulak KGhosh Center for Phononics and Thermal Energy Science Shanghai Key Laboratory of Special Artificial Microstructure Materials and TechnologySchool of Physics Science and EngineeringTongji UniversityShanghai 200092China Dipartimento di Fisica Universitàdi CamerinoI-62032 CamerinoItaly Department of Chemistry Presidency UniversityKolkataIndia

We numerically investigate the transport of a passive colloidal particle in a periodic array of planar counterrotating convection rolls,at high Peclet *** is shown that an external bias,oriented parallel to the array,produces a huge excess diffusion peak,in cases where bias and advection drag become *** effect is not restricted to one-dimensional convection geometries,and occurs independently of the array’s boundary conditions.

关键词： conditions. rotating Diffusion

Enhanced photocatalytic activity of methylene blue using heterojunction Ag@TiO_(2)nanocomposite:Mechanistic and optimization study

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Chinese Journal of Chemical Engineering 2023年第12期64卷 49-63页

作者： Saptarshi Ghosh Kamalesh Sen Priyanka debnath Arghadip Mondal Naba Kumar Mondal Aerosol and Nanoparticle Technology Laboratory Environmental Science and Engineering Department.Indian Institute of Technology BombayMumbai 400076India Environmental Chemistry Laboratory Department of Environmental ScienceThe University of BurdwanW.B 713104India

The objective in this study is to investigate the adsorption-degradation of the methylene blue(MB)dye using a fabricated heterojunction Ag@TiO_(2)*** batch factors used in photo catalytic reactions were pH,UV-irradiation time,temperature,catalytic dosage,and concentration of *** results showed that 0.2×10^(3) g·ml^(-1))of the catalytic dose caused the Ag@TiO_(2)adsorption to degrade by 96.67%with darks and UV *** the Langmuir-Hinshelwood model to determine the kinetic,the Ag@TiO_(2)displays a greater kinetic rate than TiO_(2)and silver nanoparticle(AgNPs).The photocatalytic degradation of MB,which is an endothermic reaction involving all catalysts,is shown by the thermodynamic parameter to have the positive value of enthalpy(ΔH°).The enthalpies observed were Ag@TiO_(2)(126.80 kJ·mol^(-1))

关键词： Heterojunction Ag@TiO_(2)nanocomposite Methylene blue dye Langmuir-Hinshelwood model Scavenger Density functional theoty

Microwave-assisted rapid synthesis of alumina nanoparticles using tea,coffee and triphala extracts

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Advances in Manufacturing 2013年第4期1卷 357-361页

作者： Prasant Sutradhar Narayan debnath Mitali Saha Department of Chemistry National Institute of Technology

Alumina nanoparticles （A1NP） were synthe- sized from aluminium nitrate using extracts of tea, coffee and triphala--a well known herbal plant as well as a non- toxic and eco--friendly green material. The synthesis was carried out taking 1：4 ratio of metal salt and these extracts under microwave irradiations at 540 W, which gave better yield of nanoparticles. Water was taken as solvent medium. The formations of A1NP were initially monitored by the colour changes occurring in the reaction mixture during the incubation period. As synthesized nanoparticles were characterized by scanning electron microscope （SEM）, UV-Visible （UV-Vis） spectroscopy and Fourier transform infrared spectroscopy （FTIR）. The A1NP were found to be spherical in shape in case of tea and coffee extracts with a size of 50-200 nm and to be oval shaped in case of triphala extract with an average size of 200-400 nm. The formation of A1NP with the microwave-assistance using these plant extracts has proved to be very faster than any other methods. In addition, excellent reproducibility of these nanoparticles, without the use of any additional capping agent or stabilizer will have great advantages in compari- son with microbial synthesis, avoiding all the tedious and hygienic complications.

关键词： Alumina nanoparticles ~ Microwave .Tea ~ Coffee ~ Triphala

Spectral analysis of χ class data of GRS 1915+105 using TCAF solution

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Research in Astronomy and Astrophysics 2020年第12期20卷 347-356页

作者： Anuvab Banerjee Ayan Bhattacharjee Dipak debnath Sandip K.Chakrabarti S.N.Bose National Centre for Basic Sciences Block-JDSector-3Salt LakeKolkata700106India Indian Centre for Space Physics 43 ChalantikaGaria St.Rd.Kolkata700084India

The class variable source GRS 1915+105 exhibits a wide range of time variabilities on timescales of a few seconds to a few days. Depending on the count rates in different energy bands and the nature of the conventional color-color diagram, the variabilities were classified into sixteen classes that were later sequenced in ascending order of Comptonization Efficiency(CE), which is the ratio of power-law and blackbody photons. However, CE estimation is based on an empirical model which does not provide us with a comprehensive picture regarding accretion flow dynamics around the central source. In reality, the accretion flow is comprised of two components: the high angular momentum Keplerian flow in the form of a radiatively efficient disk and a low angular momentum radiatively inefficient sub-Keplerian halo enveloping the disk. These two components contribute differently to the overall flux due to the differences in their radiative efficiencies. Therefore, it is necessary to analyze the spectral behaviors and time variabilities in terms of accretion rates. In χ class, X-ray flux is steady with no significant variation, however various χsubclasses are observed at different X-ray fluxes and variations of count rates across different χ subclasses must be linked to the variation of flow parameters such as the accretion rates, be it the Keplerian disk rate and/or the low angular momentum halo rate. This motivated us to analyze the spectra of the χ class data implementing the physical Two Component Advective Flow(TCAF) solution which directly extracts these two rates from spectral fits. We find that in the χ2,4 classes, which are reportedly devoid of significant outflows, the spectra could be fitted well applying the TCAF solution alone. In the χ1,3 classes, which are always linked with outflows, a cutoff power-law model is needed in addition to the TCAF *** the same time, the normalization required by this model along with the variation of photon index and exponent

关键词： X-Rays:binaries stars:individual(GRS 1915+105) stars:black holes accretion,accretion disks ISM:jets and outflows radiation:dynamics

Hydrodynamic dispersion of reactive solute in a Hagen–Poiseuille flow of a layered liquid

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Chinese Journal of Chemical Engineering 2017年第7期25卷 862-873页

作者： Sudip debnath Apu Kumar Saha B.S.Mazumder Ashis Kumar Roy Department of Mathematics National Institute of TechnologyAgartala 799046India Fluvial Mechanics Laboratory Physics and Applied Mathematics UnitIndian Statistical InstituteKolkata 700108India Fluid Mechanics and Hydraulic Laboratory(FMHL) Department of Aernspace Engineering and Applied MechanicsIndian Institute of Engineering Science and Technology(IIEST)ShibpurHowrah 711103India

An analysis of the solute dispersion in the liquid flowing through a pipe by means of Aris–Barton's ‘method of moments', under the joint effect of some finite yield stress and irreversible absorption into the wall is presented in this paper. The liquid is considered as a three-layer liquid where the center region is Casson liquid surrounded by Newtonian liquid layer. A significant change from previous modelling exercises in the study of hydrodynamic dispersion, different molecular diffusivity has been considered for the different region yet to be constant. For all time period, finite difference implicit scheme has been adopted to solve the integral moment equation arising from the unsteady convective diffusion equation. The purpose of the study is to find the dependency of solute transport coefficients on absorption parameter, yield stress, viscosity ratio, peripheral layer variation and in addition with various diffusivity coefficients in different liquid layers. This kind of study may be useful for understanding the dispersion process in the blood flow analysis.

关键词： Casson liquid Yield stress Axial-dispersion coefficient Irreversible reaction Diffusivity

Accretion flow properties of XTE J1118+480 during its 2005 outburst

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Research in Astronomy and Astrophysics 2020年第11期20卷 222-230页

作者： Dipak debnath Debjit Chatterjee Arghajit Jana Sandip K.Chakrabarti Kaushik Chatterjee Indian Centre for Space Physics 43 ChalantikaGaria St.Rd.Kolkata700084India Physical Research Laboratory NavrangpuraAhmedabad 380009India

We study spectral and temporal properties of Galactic short orbital period transient black hole XTE J1118+480 during its 2005 outburst using archival data of RXTE PCA and HEXTE instruments in the combined energy range of 3−100 *** analysis with the physical two component advective flow(TCAF)model allows us to understand the accretion flow properties of the *** found that this outburst of XTE J1118+480 is an unconventional outburst as the source was only in the hard state(HS).Our spectral analysis suggests that during the entire outburst,the source was highly dominated by the low angular momentum sub-Keplerian halo *** the source was active in radio throughout the outburst,we make an effort to estimate X-ray contribution of jets to total observed X-ray emissions from the spectral analysis with the TCAF *** total X-ray intensity shows a similar nature of evolution as that of radio and jet X-ray *** allowed us to define this‘outburst’also as a jet dominated‘outburst’.Total X-ray flux is also found to subside when jet activity *** detailed spectral analysis also indicated that although the source was only in the HS during the outburst,in the late declining phase the spectrum became slightly softer due to the slow rise in the Keplerian disk rate.

关键词： X-Rays binaries-stars black holes-stars individual (XTE J1118+480)-accretion,accretion disks-ISM jets and outflows-radiation dynamics

New iridoid glucoside from Wendlandia tinctoria roots

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Chinese Chemical Letters 2011年第10期22卷 1233-1236页

作者： Biswanath Dinda Sudhan debnath Santanu Majumder Noriko Sato Yoshihiro Harigaya Department of Chemistry Tripura UniversitySuryamaninagar 799130AgartalaIndia Department of Chemistry MBB College 799004AgartalaIndia Department of Chemistry Iswarchandra Vidyasagar CollegeBelonia 799155South TripuraIndia School of Pharmaceutical Sciences Kitasato University5-9-1 ShirokaneMinato-kuTokyo 108 8641Japan

A new iridoid glucoside,10-O-veratroyleranthemoside（1） was isolated from the roots of Wendlandia *** structure was established by spectroscopic（including 2D NMR） and chemical methods.

关键词： Wendlandia tinctoria Rubiaceae Iridoid glucoside 10-O-Veratroyleranthemoside

Diversity and endophytic fungal composition in Ananas comosus(L.)*** queen cultivar isolated from three different growing conditions

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Studies in Fungi 2020年第1期5卷 310-319页

作者： Bhattacharya S debnath S Saha AK Department of Botany M.B.B.CollegeAgartala-799004TripuraIndia Mycology and Plant Pathology Laboratory Department of BotanyTripura UniversitySuryamaninagar-799022TripuraIndia

Present study deals with the isolation of endophytic fungi from leaf and root explants of Ananus comosus var queen from three growing conditions ***,cultivated as monoculture and cultivated as mixed cropping system with rubber plants.A total of twenty-nine endophytic fungal strains along with two nonsporulating forms were isolated from the host plant from three experimental *** maximum numbers of fungal strains were found belong to family Aspergillaceae and order *** highest rates of colonization and isolation(p<0.05)of endophytic fungi have been reported in wild foliar explants(95.53±0.53)and monoculture(1.02±0.01),*** highest relative frequency was observed among isolated fungal strains in the case of Lasiodiplodia theobromae isolated from the leaf and root of wild(26.22%)and monoculture(29.62%)*** *** and Aspergillus flavus,isolated from the leaf and roots of wild(21.66%)and monoculture(14.66%)explants showed the highest colonization *** findings showed that the distribution of fungal endophytes and their relative frequency in host plants vary in three different growing conditions.

关键词： Colonization frequency Fungal endophytes Mixed cropping Monoculture Pineapple

A New Bis-iridoid Glucoside from Mussaenda incana

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Chinese Chemical Letters 2006年第10期17卷 1331-1334页

作者： Biswanath DINDA Sudhan debnath Santanu MAJUMDER Shiho ARIMA Nariko SATO Yoshihiro HARIGAYA Department of Chemistry Tripura University Suryamaninagar 799-130 Agartala India Department of Chemistry Belonia College Belonia 799-155 India School of Pharmaceutical Sciences Kitasato University Minato-ku Tokyo 108-8641 Japan

A new bis-iridoid glucoside, incaside 1 was isolated along with known iridoid, 6-0- veratroylcatalposide from the stem-bark of Mussaenda incana. The structure of the new iridoid was established mainly on the basis of ... 详细信息

关键词： Mussaenda incana Rubiaceae incaside bis-iridoid glucoside.