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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

Unravelling the bottleneck of phosphonic acid anchoring groups aiming toward enhancing the stability and efficiency of mesoscopic solar cells

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Frontiers of Chemical science and Engineering 2022年第7期16卷 1060-1078页

作者： Ajendra Kumar Vats Pritha roy Linjun Tang shuzi Hayase shyam s.Pandey Graduate school of Life science and systems Engineering Kyushu Institute of TechnologyKitakyushu 808-0196Japan i-Powered Energy system Research Center(i-PERC) The University of Electro-CommunicationsTokyo 182-8585Japan

Novel near-infrared sensitizers with different anchoring groups aiming toward improved stability and efficiency of dye-sensitized solar cells were synthesized. Adsorption of these dyes on the mesoporous TiO_(2) surface revealed the dye adsorption rate of –CH=CH–COOH (sQ-139)>–CH=C(CN)COOH (sQ-140)>–PO_(3)H_(2) (sQ-143)>–CH=C(CN)PO_(3)H_(2) (sQ-148)>–CH=C(CN)PO_(3)H–C_(2)H_(5) (sQ-157)>–PO_(3)H–C_(2)H_(5) (sQ-151)> –CH=CH–COOH(–PO_(3)H_(2)) (sQ-162). The binding strength of these dyes on mesoporous TiO_(2) as investigated by dye desorption studies follows sQ-162>sQ-143>sQ-148>sQ-139≫sQ-157~sQ-151≫sQ-140 order. The acrylic acid anchoring group was demonstrated to be an optimum functional group owing to its fast dye adsorption rate and better binding strength on TiO_(2) along with good photoconversion efficiency. Results of dye binding on TiO_(2) surface demonstrated that sQ-162 bearing double anchoring groups of phosphonic and acrylic acid exhibited>550 times stronger binding as compared to dye sQ-140 having cyanoacrylic acid anchoring group. sQ-140 exhibited the best photovoltaic performance with photon harvesting mainly in the far-red to near-infrared wavelength region having short circuit current density, open-circuit voltage and fill factor of 14.28 mA·cm^(–2), 0.64 V and 0.65, respectively, giving the power conversion efficiency of 5.95%. Thus, dye sQ-162 not only solved the problem of very poor efficiency of dye bearing only phosphonic acid while maintaining the extremely high binding strength opening the path for the design and development of novel near-infrared dyes with improved efficiency and stability by further increasing the π-conjugation.

关键词： anchoring groups adsorption behaviour dye-binding strength squaraine dyes dye-sensitized solar cells

Time evolution of the matter content of the expanding universe in the framework of Brans-Dicke gravity

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Research in Astronomy and Astrophysics 2019年第4期19卷 137-150页

作者： sudipto roy Department of Physics St.Xavier's College30 Mother Teresa Sarani (Park Street)

A cosmological model has been constructed in the framework of Brans-Dicke(BD) gravity,based on an inter-conversion between matter and dark energy, for a spatially flat universe in the era of pressureless dust. To account for the non-conservation of the matter content, a function of time f(t) has been arbitrarily put into the expression for the density of matter(ρa^3= f(t)ρ_0 a_0~3). By definition, f(t) is proportional to the matter content of the universe. Using suitable ansatzes for the scale factor and scalar field, the functional form of f(t) has been determined from the BD field equations. The scale factor has been so chosen that it would cause a signature flip in the deceleration parameter with time. The function f(t) decreases monotonically with time, indicating a transformation of matter into dark energy. The time dependence of the proportions of matter and dark energy in the universe has been determined. The effect of non-conservation of the matter content upon various cosmological parameters has been explored in the present study. Two models of matter-energy interaction have been proposed and f(t) has been expressed as a function of their interaction term. The dark energy equation-of-state(Eos) parameter has been expressed and analyzed in terms of f(t).

关键词： cosmology:cosmological parameters dark energy Brans-Dicke theory

Microwave-assisted reduction roasting–magnetic separation studies of two mineralogically different low-grade iron ores

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International Journal of Minerals,Metallurgy and Materials 2020年第11期27卷 1449-1461页

作者： subhnit K.roy Deepak Nayak Nilima Dash Nikhil Dhawan swagat s.Rath Mineral Processing Department CSIR-Institute of Minerals and Materials TechnologyBhubaneswar 751013India Department of Metallurgical and Materials Engineering Indian Institute of TechnologyRoorkee 247667India

The microwave-assisted reduction behaviours of two low-grade iron ores having a similar Fe content of 49wt%but distinctly different mineralogical and liberation characteristics were *** performances in terms of the iron grade and recovery as obtained from statistically designed microwave(MW)roasting followed by low-intensity magnetic separation(LIMs)experiments were *** respective optimum conditions,the titano-magnetite ore(O1)could yield an iron concentrate of 62.57%Fe grade and 60.01%Fe recovery,while the goethitic ore(O2)could be upgraded to a concentrate of 64.4%Fe grade and 33.3%Fe *** with the goethitic ore,the titanomagnetite ore responded better to MW *** characterization studies of the feed and roasted products obtained at different power and time conditions using X-ray diffraction,optical microscopy,vibrating-sample magnetometry,and electron-probe microanalysis explain the sequential reduction in the iron oxide ***,taking advantage of the MW absorbing character of the titano-magnetite ore,a blend of the same with the goethite-rich ore at a weight ratio of 60:40(O2:O1)was subjected to MW roasting that resulted in a concentrate of 61.57%Fe grade with a Fe recovery of 64.47%.

关键词： microwave reduction roasting titano-magnetite ore goethitic ore magnetic separation

Resilient modulus prediction of soft low-plasticity Piedmont residual soil using dynamic cone penetrometer

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Journal of Rock Mechanics and Geotechnical Engineering 2018年第2期10卷 323-332页

作者： s.Hamed Mousavi Mohammed A.Gabr roy H.Borden Department of Civil Construction and Environmental Engineering North Carolina State University

Dynamic cone penetrometer（DCP） has been used for decades to estimate the shear strength and stiffness properties of the subgrade soils. There are several empirical correlations in the literature to predict the resilient modulus values at only a specific stress state from DCP data, corresponding to the predefined thicknesses of pavement layers（a 50 mm asphalt wearing course, a 100 mm asphalt binder course and a200 mm aggregate base course）. In this study, field-measured DCP data were utilized to estimate the resilient modulus of low-plasticity subgrade Piedmont residual soil. Piedmont residual soils are in-place weathered soils from igneous and metamorphic rocks, as opposed to transported or compacted *** the existing empirical correlations might not be applicable for these soils. An experimental program was conducted incorporating field DCP and laboratory resilient modulus tests on "undisturbed" soil specimens. The DCP tests were carried out at various locations in four test sections to evaluate subgrade stiffness variation laterally and with depth. Laboratory resilient modulus test results were analyzed in the context of the mechanistic-empirical pavement design guide（MEPDG） recommended universal constitutive model. A new approach for predicting the resilient modulus from DCP by estimating MEPDG constitutive model coefficients（k;,k;and k;） was developed through statistical analyses. The new model is capable of not only taking into account the in situ soil condition on the basis of field measurements,but also representing the resilient modulus at any stress state which addresses a limitation with existing empirical DCP models and its applicability for a specific case. Validation of the model is demonstrated by using data that were not used for model development, as well as data reported in the literature.

关键词： Dynamic cone penetrometer(DCP) Resilient modulus Mechanistic-empirical pavement design guide(MEPDG) Residual soils subgrade soils

Mose_(2)/Ws_(2) heterojunction photodiode integrated with a silicon nitride waveguide for near infrared light detection with high responsivity

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Light(science & Applications) 2023年第3期12卷 456-464页

作者： Rivka Gherabli s.R.K.C.Indukuri roy Zektzer Christian Frydendahl Uriel Levy Department of Applied Physics The Faculty of ScienceThe Center for Nanoscience and NanotechnologyThe Hebrew University of JerusalemJerusalem91904Israel

We demonstrate experimentally the realization and the characterization of a chip-scale integrated photodetector for the near-infrared spectral regime based on the integration of a Mose_(2)/Ws_(2) heterojunction on top of a silicon nitride *** configuration achieves high responsivity of~1 A W−1 at the wavelength of 780 nm(indicating an internal gain mechanism)while suppressing the dark current to the level of~50 pA,much lower as compared to a reference sample of just Mose_(2) without Ws_(2).We have measured the power spectral density of the dark current to be as low as~1×10^(−12) A Hz−0.5,from which we extract the noise equivalent power(NEP)to be~1×10^(−12) W Hz^(−0.5).To demonstrate the usefulness of the device,we use it for the characterization of the transfer function of a microring resonator that is integrated on the same chip as the *** ability to integrate local photodetectors on a chip and to operate such devices with high performance at the near-infrared regime is expected to play a critical role in future integrated devices in the field of optical communications,quantum photonics,biochemical sensing,and more.

关键词： heterojunction waveguide resonator

Targeting BPOZ-2 in Lewy body disease

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Neural Regeneration Research 2016年第6期11卷 910-911页

作者： Avik roy Department of Neurological sciences Rush University Medical Center

Formation of Lewy body inclusions（LBs）in the substantia nigra（sN）is a very well-characterized pathological hallmark of Parkinson’s disease（PD）.LBs are aggregates of many biologically inactive proteins including structural elements,alpha-synuclein（asyn）-binding proteins,synphilin-1-binding proteins,and components of the ubiquitin-proteasome system.

关键词： Targeting substantia proteasome nigra ubiquitin biologically inactive mitochondria dopamine parkin

Partial genomic organization of ribosomal protein s7 gene from malaria vector Anopheles stephensi

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Insect science 2007年第2期14卷 101-106页

作者： RAJNIKANT DIXIT sARITA DIXIT UPAL roy YOGEsH s.sHOUCHE sURENDRA GAKHAR Department of Biosciences Maharshi Dayanand University RohtakPune University Campus Pune India National Centre for Cell science Pune University Campus Pune India

In this study, we describe the partial genomic organization of ribosomal protein s7 gene isolated from the mosquito Anopheles stephensi. Initially a 558 bp partial cDNA sequence was amplified as precursor mRNA sequence containing 223 bp long intron. 5＇ and 3＇ end sequences were recovered using end specific rapid amplification of cDNA ends （RACE） polymerase chain reaction. The full-length cDNA sequence was 914 nucleotide long with an open reading frame capable of encoding 192 amino acid long protein with calculated molecular mass of 22174 Da and a pI point of 9.94. Protein homology search revealed 〉75% identity to other insect＇s s7 ribosomal proteins. Analysis of sequence alignment revealed several highly conserved domains, one of which is related to nuclear localization signal （NLs） region of human rps7. Interestingly, intron nucleotide sequence comparison with A. gambiae showed a lesser degree of conservation as compared to coding and untranslated regions. Like this, early studies on the genomic organization and cDNA/ Expressed sequence tag analysis （EsT） could help in genome annotation ofA. stephensi, and would be likely to be sequenced in the future.

关键词： Anopheles malaria mosquito ribosomal protein vector

supramolecular organization of the sperm plasma membrane during maturation and capacitation

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Asian Journal of Andrology 2007年第4期9卷 438-444页

作者： roy Jones Peter s. James Liz Howes Andreas Bruckbauer David Klenerman The Babraham Institute Cambridge CB2 4AT UK Department of Chemistry University of Cambridge Cambridge CB2 1EW UK

Aim： In the present study, a variety of high resolution microscopy techniques were used to visualize the organization and motion of lipids and proteins in the sperm＇s plasma membrane. We have addressed questions such as the presence of diffusion barriers, confinement of molecules to specific surface domains, polarized diffusion and the role of cholesterol in regulating lipid rafts and signal transduction during capacitation. Methods： Atomic force microscopy identified a novel region （Eqss） within the equatorial segment of bovine, porcine and ovine spermatozoa that was enriched in constitutively phosphorylated proteins. The Eqss was assembled during epididymal maturation. Fluorescence imaging techniques were then used to follow molecular diffusion on the sperm head. Results： single lipid molecules were freely exchangeable throughout the plasma membrane and showed no evidence for confinement within domains. Large lipid aggregates, however, did not cross over the boundary between the post-acrosome and equatorial segment suggesting the presence of a molecular filter between these two domains. Conclusion： A small reduction in membrane cholesterol enlarges or increases lipid rafts concomitant with phosphorylation of intracellular proteins. Excessive removal of cholesterol, however, disorganizes rafts with a cessation of phosphorylation. These techniques are forcing a revision of long-held views on how lipids and proteins in sperm membranes are assembled into larger complexes that mediate recognition and fusion with the egg. （Asian JAndrol 2007 July; 9： 438-444）

关键词： cholesterol lipid rafts single molecules sperm membranes