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An empirical method for estimating surface area of aggregates in hot mix asphalt

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Journal of Traffic and Transportation Engineering(English Edition) 2016年第2期3卷 127-136页

作者： R.P.Panda sudhanshu sekhar das P.K.Suhoo Department of Civil Engineering Siksha'O'Anusandhan UniversityBhubanesvoarIndia Institute of Technical Education and Research Siksha'O'Anusandhan UniversityBhubaneswarIndia Department of Civil Engineering Veer Surendra Sai University of TeehologyBurlaIndia

Bitumen requirement in hot mix asphalt （HMA） is directly dependent on the surface area of the aggregates in the mix, which in turn has effect on the asphalt film thickness and the flow characteristics. The surface area of aggregate blend in HMA is calculated using the specific surface area factors assigned to percentage passing through some specific standard sieve sizes and the imaging techniques. The first process is less capital intensive, but purely manual and labour intensive and prone to human errors. Imaging techniques though eliminating the human errors, still have limited use due to capital intensiveness and requirement of well-established ]aboratories with qualified technicians. Most of the developing countries like India are shortage of well-equipped laboratories and qualified technicians. To overcome these difficulties, the present mathematical model has been developed to estimate the surface area of aggregate blend of HMA from physical properties of aggregates evaluated using simple laboratory equipment. This model has been validated compared with the existing established methods of calculations and can be used as one of the tools in different developing and under developed countries for proper design of HMA.

关键词： Surface area of aggregates Physical properties of aggregates Hot mix asphalt Film thickness

Comparative Analysis of RNAi Suppression Activity of Proteins from Two Disparate Viruses

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American Journal of Plant Sciences 2014年第12期5卷 1789-1798页

作者： sudhanshu sekhar das Neeti Sanan-Mishra Plant Molecular Biology Group International Centre for Genetic Engineering and Biotechnology New Delhi India

RNAi is an efficient surveillance machinery that plays a robust defensive role in shielding plant and animal hosts against viral infections. In counter-defense viruses encode suppressor proteins that have the ability to restrict the RNAi machinery to ensure successful systemic invasion. The B2 protein of insect Flock House Virus (FHV-B2) and AC2 protein of Mungbean Yellow Mosaic India Virus (MYMIV-AC2) are two well-characterized suppressors of RNAi, capable of reversing reporter gene silencing. In this study, we compared the strength of the two suppressors by assaying for the degree of RNAi reversion and the duration of sustaining the reversal in planta. The suppression activity was observed by assaying for GFP fluorescence at 3 dpi, 7 dpi and 14 dpi. The phenotypic observations were corroborated with small RNA Northern Blotting and semi-quantitative RT-PCR. The results indicate that suppressor strength of FHVB2 is comparable to MYMIV-AC2, although they are encoded by virus infecting host from two different eukaryotic kingdoms. This study will provide new insights to dissect the conservation in the RNAi pathways during the host-virus interactions.

关键词： MYMIV-AC2 FHVB2 Agroinfiltration RNA Silencing Suppressor (RSS) Reversal of GFP Silencing Assay

Study of grain alignment efficiency and a distance estimate for small globule CB4

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Research in Astronomy and Astrophysics 2015年第7期15卷 953-962页

作者： Ajoy Barman Himadri sekhar das Department of Physics Assam University

We study the polarization efficiency（defined as the ratio of polarization to extinction） of stars in the background of the small, nearly spherical and isolated Bok globule CB4 to understand the grain alignment process. A decrease in polarization efficiency with an increase in visual extinction is noticed. This suggests that the observed polarization in lines of sight which intercept a Bok globule tends to show dominance of dust grains in the outer layers of the globule. This finding is consistent with the results obtained for other clouds in the past. We determined the distance to the cloud CB4 using near-infrared photometry（2MASS J H KScolors） of moderately obscured stars located at the periphery of the cloud. From the extinction-distance plot,the distance to this cloud is estimated to be（459 ± 85） pc.

关键词： polarization -- ISM: clouds -- dust extinction -- ISM: individual ob-jects: CB4

Correlation among extinction efficiency and other parameters in an aggregate dust model

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Research in Astronomy and Astrophysics 2017年第11期17卷 95-112页

作者： Tanuj Kumar Dhar Himadri sekhar das Department of Physics Assam University Silchar 788011 India

We study the extinction properties of highly porous Ballistic Cluster-Cluster Aggregate dust aggregates in a wide range of complex refractive indices （1.4 ≤ n 〈 2.0, 0.001 ≤ k 〈 1.0） and wavelengths （0.11 μm 〈 A 〈 3.4 μm）. An attempt has been made for the first time to investigate the correlation among extinction efficiency （Qext）, composition of dust aggregates （n, k）, wavelength of radiation （A） and size parameter of the monomers （x）. If k is fixed at any value between 0.001 and 1.0, Qext increases with increase of n from 1.4 to 2.0. Qext and n are correlated via linear regression when the cluster size is small, whereas the correlation is quadratic at moderate and higher sizes of the cluster. This feature is observed at all wavelengths （ultraviolet to optical to infrared）. We also find that the variation of Qext with n is very small when A is high. When n is fixed at any value between 1.4 and 2.0, it is observed that Qext and k are correlated via a polynomial regression equation （of degree 1, 2, 3 or 4）, where the degree of the equation depends on the cluster size, n and A. The correlation is linear for small size and quadratic/cubic/quartic for moderate and higher sizes. We have also found that Qext and x are correlated via a polynomial regression （of degree 3, 4 or 5） for all values of n. The degree of regression is found to be n and k-dependent. The set of relations obtained from our work can be used to model interstellar extinction for dust aggregates in a wide range of wavelengths and complex refractive indices.

关键词： light scattering -- ISM: dust extinction

Aggregate dust model to study the polarization properties of comet C/1996 B2 Hyakutake

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Research in Astronomy and Astrophysics 2010年第4期10卷 355-362页

作者： Himadri sekhar das Abinash Suklabaidya Saonli Datta Majumder Asoke Kumar Sen Department of Physics Assam University

The observed linear polarization data of comet Hyakutake are studied at wavelengths λ=0.365 μm,λ=0.485 μm and 0.684μm through simulations using Ballistic Particle-Cluster Aggregate and Ballistic Cluster-Cluster Aggregate aggregates of 128 spherical *** first found that the size parameter of the monomer,x ～ 1.56-1.70,turned out to be the most suitable which provides the best fits to the observed dust scattering properties at three wavelengths：λ=0.365 μm,0.485μm and 0.684μ***,the effective radius of the aggregate （r） lies in the range 0.45 μm ≤ r ≤ 0.49 μm at λ=0.365 μm;0.60 μm ≤ r ≤ 0.66 μm at λ=0.485 μm and 0.88 μm ≤ r ≤ 0.94 μm at λ=0.684 μ*** using superposition T-MATRIX code and the power-law size distribution,n（r）～ r-3,the best-fitting values of complex refractive indices are calculated for the observed polarization data at the above three *** best-fitting complex refractive indices （n,k） are found to be （1.745,0.095） at λ=0.365 μm,（1.743,0.100） at λ=0.485 μm and （1.695,0.100） at λ=0.684 μ*** refractive indices derived from the present analysis correspond to a mixture of both silicates and organics,which are in good agreement with the in situ measurement of comets by different spacecraft.

关键词： comets:general - dust extinction - scattering - polarization

Anticholinergic medications even in therapeutic range can cause recurrence of psychosis

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General Psychiatry 2020年第4期33卷 245-246页

作者： Soumitra das Seshadri sekhar Chatterjee Barikar Chandrappa Malathesh Psychiatry Northwestern Mental HealthMelbourneVictoriaAustralia Psychiatry Diamond Harbour Medical CollegeDiamond HarbourIndia Psychiatry National Institute of Mental Health and Neuro SciencesBangaloreIndia

Anticholinergic drugs are commonly used in psychiatry to attenuate antipsychotic induced extrapyramidal syndrome(EPS).Psychosis as a side effect is generally explained under the rubric of anticholinergic toxicity or induced *** induced worsening of psychosis in patients with normal cognition is extremely rare in ***,we arepresenting a case of young female who was prescribed with multiple anticholinergics to reduce EPS,and each time had worsening of psychosis with intact *** then discussed the possible neurobiological explanation with special reference to muscarinic hypothesis of schizophrenia.

关键词： cholinergic drugs prescribed

Synthesis of Mg(OH)_(2) micro/nano flowers at room temperature

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Journal of Advanced Ceramics 2013年第2期2卷 173-179页

作者： Pradip sekhar das Arjun DEY Ashok Kumar MANDAL Nitai DEY Anoop K.MUKHOPADHYAY CSIR-Central Glass and Ceramic Research Institute Kolkata 700032India Thermal Systems Group ISRO Satellite CentreVimanapura PostBangalore 560017India

The inexpensive and green method of synthesis for self-assembled micro/nano structures is an important area of emerging *** structures can be chemically tuned with predesigned functional ***,they hold very good promise for future applications,e.g.,biomedicine,electronic device,solar energy,gas *** we report for the first time an inexpensive and green method for chemical deposition of magnesium hydroxide(Mg(OH)_(2))micro/nano flowers in thin films on commercial soda lime silica glass substrates at room *** identical conditions,chemically synthesized Mg(OH)_(2) powders are also prepared in absence of the soda lime silica glass *** condition that favors the growth of micro/nano flowers in thin films is identified from X-ray diffraction(XRD),scanning electron microscopy(SEM),field emission scanning electron microscopy(FE-SEM),transmission electron microscopy(TEM),and energy dispersive X-ray spectroscopy(EDX)***,the possible growth mechanism of micro/nano flowers in thin films is discussed.

关键词： magnesium hydroxide(Mg(OH)2) flower-like microstructure chemical deposition film

Overview of mental health issues of COVID-19:need of the hour

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General Psychiatry 2020年第3期33卷 189-190页

作者： Barikar Chandrappa Malathesh Seshadri sekhar Chatterjee Soumitra das Department of Psychiatry National Institute of Mental Health and Neuro SciencesBangaloreIndia Department of Psychiatry West Bengal University of Health SciencesKolkataIndia NorthWestern Mental Health ParkvilleVictoriaAustralia

To the Editor,First detected in Wuhan,China,severe acute respiratory syndrome coronavirus 2(SARS CoV 2)virus is creating havoc worldwide and having an unprecedented impact on public health and society,so much so that it was declared a'Public Health Emergency of International Concern’in January 2020 and further as a‘pandemic’in March *** far,it has affected more than 1.7 million people all over the world,causing 110 thousand deaths across 195 countries.

关键词： acute respiratory Wuhan

Low-cost high entropy alloy(HEA)for high-efficiency oxygen evolution reaction(OER)

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Nano Research 2022年第6期15卷 4799-4806页

作者： Lalita Sharma Nirmal Kumar Katiyar Arko Parui Rakesh das Ritesh Kumar Chandra sekhar Tiwary Abhisek K.Singh Aditi Halder Krishanu Biswas School of Basic Sciences Advanced Materials Research Centre(AMRC)Indian Institute of Technology Mandi(H.P)KamandMandi 175005India Department of Materials Science and Engineering Indian Institute of Technology KanpurKanpur 208016India School of Engineering London South Bank UniversityLondonSE10 AAUK Materials Research Centre Indian Institute of ScienceBangalore 560012India Metallurgical and Materials Engineering Indian Institute of Technology KharagpurKharagpur 382355India

Oxygen evolution reaction(OER)is the key step involved both in water splitting devices and rechargeable metal-air batteries,and hence,there is an urgent need for a stable and low-cost material for efficient *** the present investigation,Co-Fe-Ga-NiZn(CFGNZ)high entropy alloy(HEA)has been utilized as a low-cost electrocatalyst for ***,after cyclic voltammetry activation,CFGNZ-nanoparticles(NPs)are covered with oxidized surface and form high entropy(oxy)hydroxides(HEOs),exhibiting a low overpotential of 370 mV to achieve a current density of 10 mA/cm^(2)with a small Tafel slope of 71 mV/*** alloy has higher electrochemical stability in comparison to state-of-the art RuO2 electrocatalyst as no degradation has been observed up to 10 h of *** electron microscopy(TEM)studies after 10 h of long-term chronoamperometry test showed no change in the crystal structure,which confirmed the high stability of *** density functional theory(DFT)based calculations show that the closeness of d(p)-band centers to the Fermi level(EF)plays a major role in determining active *** work highlights the tremendous potential of CFGNZ HEA for OER,which is the primary reaction involved in water splitting.

关键词： high entropy alloy cyclic voltammetry activation oxygen evolution reaction electrocatalyst nanocrystalline catalyst