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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

Structural,optical,electrical,and dielectric relaxation properties of rare earth containing sodium bismuth titanate Na_(0.5)bi_(0.5)TiO_(3) perovskite:Effect of ionic radius

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Journal of Rare Earths 2024年第2期42卷 383-391,I0006页

作者： Rajdip roy Abhigyan Dutta Department of Physics The University of BurdwanBurdwan713104India

The main focus of this work is to study the effect of the ionic radius of different rare earth dopant cations RE^(3+)(RE=La,Sm,Dy,and Ho) on structural and various physical properties of sodium bismuth titanate(Na_(0.5)b_(0.5)TiO_(3),NbT) based perovskite *** X-ray diffraction data indicate the successful formation of the rhombohedral phase(space group R3c) of NbT nano perovskite incorporated with various rare earth ions in *** lattice parameters were found to increase linearly with the ionic radius of the dopant *** ionic radii and atomic mass of rare earth dopants appear to be essential factors in the grain growth of the prepared *** grain growth results in better crystallinity of the sample by reducing the microstrain with the increase of dopant ionic *** emission scanning electron microscopy and energy-dispersive X-ray spectra confirm the prepared compositions' phase purity and *** UV-Vis spectra reveal that La-doped NbT composition exhibits the lowest optical band gap,which unfolds the application of NbT-based perovskite as photoactive *** ac conductivity and complex impedance spectra unveil that the composition with the largest ionic radius,i.e.,La-doped NbT compound,exhibits the highest dc and bulk conductivity with the lowest activation *** frequency-dependent dielectric data follows Havriliak-Negami(HN) formalism and non-Debye type relaxation *** also indicate that La-doped NbT composition exhibits the highest dielectric strength ***,this study first elaborates that the increasing ionic radius of the rare earth dopant cation in the bi-site of NbT perovskite improves its microstructural,optical,and electrical properties.

关键词： Rare earth doped NbT Microstructural analysis Optical band gap AC Conductivity Dielectric relaxation Rare earths

A STUDY ON THE ESTIMATION OF TEMPERATURE STRUCTURE PARAMETER IN AbL WITH ELEVATED INVERSION

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Acta meteorologica Sinica 1995年第3期9卷 349-359页

作者： b.roy U.K.De b.Pal Physics Department Jadavpur University.Calcutta 700 032.India Department of Physics and Meteorology Indian Institute of TechnologyKharagpur 721 302India

Temperature structure parameter in the vertical is estimated once by using the turbulence outer scale approximation and another by using the Obukhov similarity relationship during the formation of an elevated inversion.A comparison of the profiles drawn using both the methods is done for the pur- pose of assessing the accuracy of the similarity method when applied to levels above the surface-based *** profiles obtained by both the methods are also compared with a similar profile obtained af- ter considering a bulk shear between the ground and top of the elevated layer.

关键词： kytoon Doppler sodar temperature structure parameter Obukhov similarity method elevated inversion

Effect of promoters on dynamics of gas-solid fluidized bed——Statistical and ANN approaches

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China Particuology 2007年第6期5卷 401-407页

作者： Y.K. Mohanty K.C. biswal G.K. roy b.P. Mohanty Department of Chemical Engineering GIET Gunupur 765 022 Rayagada Orissa India Department of Chemical Engineering NIT Rourkela 769008 Orissa India

In this study, a bubbling fluidized bed column, 99 mm in inside diameter and 960 mm in height, was used to investigate the effect of rod and disc promoters on fluctuation and expansion ratios. Factorial design （statistical approach） and artificial neural network （ANN） models were developed to predict the fluctuation and expansion ratios in this gas-solid fluidized bed with varying gas flow rates, bed heights, particle sizes and densities. The fluctuation and expansion predicted using these statistical and ANN models, for beds with and without promoters, were found to agree well with corresponding experiments. The statistical model was found to be superior to the ANN model due to its ability to take into account both individual and interactive effects. The rod promoters were found to be more effective in reducing bed fluctuation, and in increasing bed expansion at high gas mass velocities.

关键词： Gas-solid fluidized bed Fluctuation ratio Expansion ratio Promoter Factorial design Artificial neural network

Kinetics of thermal decomposition of hydrated minerals associated with hematite ore in a fluidized bed reactor

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International Journal of Minerals,Metallurgy and Materials 2017年第3期24卷 229-239页

作者： P.C. beuria S.K. biswal b.K. Mishra G.G. roy Institute of Minerals and Materials Technology Council of Scientific & Industrial Research Bhubaneswar-751013 India Indian Institute of Technology Kharagpur-721302 India

The kinetics of removal of loss on ignition(LOI) by thermal decomposition of hydrated minerals present in natural iron ores(i.e.,kaolinite,gibbsite,and goethite) was investigated in a laboratory-scale vertical fluidized bed reactor(FbR) using isothermal methods of kinetic *** in the FbR in batch processes were carried out at different temperatures(300 to 1200°C) and residence time(1 to 30 min) for four different iron ore samples with various LOIs(2.34wt% to 9.83wt%).The operating velocity was maintained in the range from 1.2 to 1.4 times the minimum fluidization velocity(Umf).We observed that,below a certain critical temperature,the FbR did not effectively reduce the LOI to a desired level even with increased residence *** results of this study indicate that the LOI level could be reduced by 90% within 1 min of residence time at 1100°*** kinetics for low-LOI samples(by a lower activation energy(diffusion-controlled physical moisture removal),followed by a higher activation energy(chemically controlled removal of LOI).In the case of high-LOI samples,three different kinetics mechanisms prevail at different temperature *** temperature up to 450°C,diffusion kinetics prevails(removal of physical moisture);at temperature from 450 to 650°C,chemical kinetics dominates during removal of matrix *** temperatures greater than 650°C,nucleation and growth begins to influence the rate of removal of LOI.

关键词： thermal decomposition fluidized beds kinetic analysis hydrated iron ore activation energy

Study on kinetics of thermal decomposition of low LOI goethetic hematite iron ore

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International Journal of Mining Science and Technology 2017年第6期27卷 1031-1036页

作者： beuria P.C. biswal S.K. Mishra b.K. roy G.G. Mineral Processing Department CSIR–Institute of Minerals and Materials TechnologyBhubaneswar 751013India Indian Institute of Technology Kharagpur 721302India

In the present study, the kinetics of thermal decomposition of hydrated minerals associated in natural hematite iron ores has been investigated in a fixed bed system using isothermal methods of kinetic analysis. Hydrated minerals in these hematite iron ores are kaolinite, gibbsite and goethite, which contribute to the loss on ignition(LOI) during thermal decomposition. Experiments in fixed bed have been carried out at variable bed depth(16, 32, 48 and 64 mm),temperature(400-1200 ℃) and residence time(30,45, 60 and 75 min) for iron ore samples. It is observed that beyond a certain critical bed depth(16 mm), 100% removal of LOI is not found possible even at higher temperature and higher residence time. Most of the solid-state reactions of isothermal kinetic analysis have been used to analyze the reaction mechanism. The raw data are modified to yield fraction reacted "α" versus time and used for developing various forms of "α" functions.f(α) is the inverse of first derivative of g(α) with respect to α. The study demonstrates that decomposition of hydrated mineral in hematite follows the chemical *** estimated activation energy values in all the experimental situations are found to high, of the order of 60 kJ/mol, reinstating that the reactions are indeed controlled by moving phase boundary and random nucleation.

关键词： Loss on ignition Goethite Kaolinite Gibbsite Roasting Pellet feed Kinetic analysis

A new four-dimensional hyperjerk system with stable equilibrium point, circuit implementation, and its synchronization by using an adaptive integrator backstepping control

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Chinese Physics b 2018年第10期27卷 231-239页

作者： J P Singh V T Pham T Hayat S Jafari F E Alsaadi b K roy Department of Electrical Engineering National Institute of Technology Silchar 788010 India School of Electronics and Telecommunications Hanoi University of Science and Technology 01 Dai Co Viet Hanoi Viet Nam Department of Mathematics Faculty of Science King Abdulaziz University Jeddah 21589 Saudi Arabia Department of Mathematics Quaid-I-Azam University Islamabad 44000 Pakistan Ambikar University of Technology Tehran 15875-4413Iran Department of Information Technology Faculty of Computing and IT King Abdulaziz University Jeddah Saudi Arabia

This paper reports a new simple four-dimensional（4 D） hyperjerk chaotic system. The proposed system has only one stable equilibrium point. Hence, its strange attractor belongs to the category of hidden attractors. The proposed system exhibits various dynamical behaviors including chaotic, periodic, stable nature, and coexistence of various attractors. Numerous theoretical and numerical methods are used for the analyses of this system. The chaotic behavior of the new system is validated using circuit implementation. Further, the synchronization of the proposed systems is shown by designing an adaptive integrator backstepping controller. Numerical simulation validates the synchronization strategy.

关键词： new hyperjerk chaotic system stable equilibrium hidden attractors adaptive backstepping control synchronization

Mechanism of Cu entry into the brain:many unanswered questions

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Neural Regeneration Research 2024年第11期19卷 2421-2429页

作者： Shubhrajit roy Svetlana Lutsenko Department of Physiology Johns Hopkins University School of MedicineBaltimoreMDUSA

brain tissue requires high amounts of copper(Cu)for its key physiological processes,such as energy production,neurotransmitter synthesis,maturation of neuropeptides,myelination,synaptic plasticity,and radical *** requirements for Cu in the brain vary depending on specific brain regions,cell types,organism age,and nutritional *** imbalances cause or contribute to several life-threatening neurologic disorders including Menkes disease,Wilson disease,Alzheimer’s disease,Parkinson’s disease,and *** the well-established role of Cu homeostasis in brain development and function,the mechanisms that govern Cu delivery to the brain are not well *** review summarizes available information on Cu transfer through the brain barriers and discusses issues that require further research.

关键词： ATOX1 ATP7A ATP7b blood-brain barrier brain choroid plexus copper SLC31A1

Paradoxical role of Id proteins in regulating tumorigenic potential of lymphoid cells

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Frontiers of Medicine 2018年第4期12卷 374-386页

作者： Sumedha roy Yuan Zhuang Department of Immunology Duke University Medical Center Durham NC 27710 USA

A family of transcription factors known as Id proteins, or inhibitor of DNA binding and differentiation, is capable of regulating cell proliferation, survival and differentiation, and is often upregulated in multiple types of tumors. Due to their ability to promote self-renewal, Id proteins have been considered as oncogenes, and potential therapeutic targets in cancer models. On the contrary, certain Id proteins are reported to act as tumor suppressors in the development of burkitt＇s lymphoma in humans, and hepatosplenic and innate-like T cell lymphomas in mice. The contexts and mechanisms by which Id proteins can serve in such contradictory roles to determine tumor outcomes are still not well understood. In this review, we explore the roles of Id proteins in lymphocyte development and tumorigenesis, particularly with respect to inhibition of their canonical DNA binding partners known as E proteins. Transcriptional regulation by E proteins, and their antagonism by Id proteins, act as gatekeepers to ensure appropriate lymphocyte development at key checkpoints. We re-examine the derailment of these regulatory mechanisms in lymphocytes that facilitate tumor development. These mechanistic insights can allow better appreciation of the context-dependent roles of Id proteins in cancers and improve considerations for therapy.

关键词： Id proteins lymphoma leukemia T cells b cells tumor suppressor oncogene