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Solving the electronic structure problem with machine learning

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npj Computational Materials 2019年第1期5卷 959-965页

作者： Anand chandrasekaran Deepak Kamal Rohit Batra Chiho Kim Lihua Chen Rampi Ramprasad School of Materials Science and Engineering Georgia Institute of Technology771 Ferst Dr.NWAtlantaGA 30332USA

Simulations based on solving the Kohn-Sham(KS)equation of density functional theory(DFT)have become a vital component of modern materials and chemical sciences research and development *** its versatility,routine DFT calculations are usually limited to a few hundred atoms due to the computational bottleneck posed by the KS *** we introduce a machine-learning-based scheme to efficiently assimilate the function of the KS equation,and by-pass it to directly,rapidly,and accurately predict the electronic structure of a material or a molecule,given just its atomic configuration.A new rotationally invariant representation is utilized to map the atomic environment around a grid-point to the electron density and local density of states at that *** mapping is learned using a neural network trained on previously generated reference DFT results at millions of *** proposed paradigm allows for the high-fidelity emulation of KS DFT,but orders of magnitude faster than the direct ***,the machine learning prediction scheme is strictly linear-scaling with system size.

关键词： solution. equation. structure

Thermophoresis and Brownian motion effects on boundary layer flow of nanofluid in presence of thermal stratification due to solar energy

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Applied Mathematics and Mechanics(English Edition) 2012年第6期33卷 765-780页

作者： N.ANBUCHEZHIAN K.SRINIVASAN K.chandrasekaran R.KANDASAMY Department of Mechanical Engineering Sri Guru Institute of Technology Department of Mechanical Engineering Anna University Department of Mechanical Engineering R.M.K.Engineering College Research Centre for Computational Mathematics Faculty of ScienceTechnology and Human DevelopmentUniversiti Tun Hussein Onn Malaysia

The problem of laminar fluid flow, which results from the stretching of a vertical surface with variable stream conditions in a nanofluid due to solar energy, is in- vestigated numerically. The model used for the nanofluid incorporates the effects of the Brownian motion and thermophoresis in the presence of thermal stratification. The sym- metry groups admitted by the corresponding boundary value problem are obtained by using a special form of Lie group transformations, namely, the scaling group of transfor- mations. An exact solution is obtained for the translation symmetrys, and the numerical solutions are obtained for the scaling symmetry. This solution depends on the Lewis number, the Brownian motion parameter, the thermal stratification parameter, and the thermophoretic parameter. The conclusion is drawn that the flow field, the temperature, and the nanoparticle volume fraction profiles are significantly influenced by these param- eters. Nanofluids have been shown to increase the thermal conductivity and convective heat transfer performance of base liquids. Nanoparticles in the base fluids also offer the potential in improving the radiative properties of the liquids, leading to an increase in the efficiency of direct absorption solar collectors.

关键词： solar radiation Brownian motion nanofluid thermophoresis thermalstratification

Cytogenetic studies of chromium(Ⅲ) oxide nanoparticles on Allium cepa root tip cells

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Journal of Environmental Sciences 2015年第12期27卷 150-157页

作者： Deepak Kumar A.Rajeshwari Pradeep Singh Jadon Gouri Chaudhuri Anita Mukherjee Natarajan chandrasekaran Amitava Mukherjee Centre for Nanobiotechnology VIT University Centre of Advanced Study Department of BotanyUniversity of Calcutta

The current study evaluates the cytogenetic effects of chromium（Ⅲ） oxide nanoparticles on the root cells of Allium *** root tip cells of *** were treated with the aqueous dispersions of Cr2O3 nanoparticles（NPs） at five different concentrations（0.01,0.1,1,10,and 100 μg/m L） for 4 *** colloidal stability of the nanoparticle suspensions during the exposure period were ascertained by particle size *** 4 hr exposure to Cr2O3 NPs,a significant decrease in mitotic index（MI） from 35.56%（Control） to 35.26%（0.01 μg/m L）,34.64%（0.1 μg/m L）,32.73%（1 μg/m L）,29.6%（10 μg/m L） and 20.92%（100 μg/m L） was *** optical,fluorescence and confocal laser scanning microscopic analyses demonstrated specific chromosomal aberrations such as-chromosome stickiness,chromosome breaks,laggard chromosome,clumped chromosome,multipolar phases,nuclear notch,and nuclear bud at different exposure *** concentration-dependent internalization/bio-uptake of Cr2O3 NPs may have contributed to the enhanced production of anti oxidant enzyme,superoxide dismutase to counteract the oxidative stress,which in turn resulted in observed chromosomal aberrations and cytogenetic *** results suggest that *** root tip assay can be successfully applied for evaluating environmental risk of Cr2O3 NPs over a wide range of concentrations.

关键词： A.cepa Bio-uptake Chromosomal aberration C2O3 nanoparticles Mitotic index SOD

Solvation number, thermochemical parameter, and viscosity study of sweeteners in aqueous and non-aqueous media through ultrasonic measurements

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ChemPhysMater 2023年第4期2卷 303-314页

作者： J.H.Rakini chandrasekaran S.Nithiyanantham Centre for Research-Department of Physics Arignar Anna Government Arts CollegeMusiri 621211India PG and Research Department of Physics Vi.Kalyanansundaram Govt Arts&Science CollegeBharathidasan UniversityThiruvarur 610003India

Ultrasonic velocity measurements are used to elucidate various aspects of solvation chemistry,including solute–solute and solute–solvent ***,an attempt is made to study a behavior of two sweeteners,D-fructose and D-sorbitol,in aqueous and non-aqueous media was attempted.D-fructose is a simple sugar found in many foods and can be consumed by diabetics and people suffering from hypoglycemia.D-Sorbitol is a sugar substitute used in diet foods,sugar-free chewing gum,mints,cough syrups,mouthwash,toothpaste etc.,D-sorbitol is an excellent humectant and texturizing agent that is also used in other products such as pharmaceuticals and *** interactions between the solute and solvent molecules are explained in terms of the solvation numbers of both aqueous and non-aqueous solutions of D-fructose and *** viscosity study correlates the viscosity of the solution with solvation;here,density,ultrasonic velocity,and viscosity of aqueous and non-aqueous solutions at various concentrations are measured at different temperatures ranging from 35 to 55℃.These parameters provide sufficient information on the interaction between molecules that may aid chemists in analyzing the mechanisms of the behavior of D-fructose and D-sorbitol in water and the water–ethanol medium through which they are *** Fourier transforms infrared spectra of pure solvent,salt,and their solutions were recorded and analyzed for confirmation.

关键词： Ultrasonic velocity Density Viscosity Solvation number Thermochemical parameters Molecular interactions FTIR spectra

Characterization and bacterial toxicity of lanthanum oxide bulk and nanoparticles

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Journal of Rare Earths 2012年第12期30卷 1298-1302页

作者： Brabu Balusamy Yamuna Gowri Kandhasamy Anitha Senthamizhan Gopalakrishnan chandrasekaran Murugan Siva Subramanian Kumaravel Tirukalikundram S Nanotechnology Research Center SRM University GLR Laboratories Private Limited Department of Physics Indian Institute of Technology-Madras GLR Laboratories Private Limited WillinghamCambridge

This study evaluated the bacterial toxicity of lanthanum oxide micron and nano sized particles using shake flask method against gram-positive （Staphylococcus aureus） and gram-negative （Escherichia coli, Pseudomonas aeruginosa） bacteria. Particle size, morphology and chemical composition were determined using scanning electron microscopy （SEM） and energy dispersive X-ray spectroscopy （EDS）. Results indicated that lanthanum oxide nanoparticles showed antimicrobial activity against Staphylococcus aureus, but not against Escherichia coli and Pseudomonas aeruginosa. It was speculated that lanthanum oxide produced this effect by interacting with the gram-positive bacterial cell wall. Furthermore, lanthanum oxide bulk particles were fotmd to enhance the pyocyanin pigment production in Pseudomonas aeruginosa.

关键词： lanthanum oxide: nanoparticles: bacterial toxicity: pyocyanin rare earths

Experimental investigation and ANN modeling on improved performance of an innovative method of using heave response of a non-floating object for ocean wave energy conversion

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Frontiers in Energy 2013年第3期7卷 279-287页

作者： Srinivasan chandrasekaran Arunachalam AMARKARTHIK Karuppan SIVAKUMAR Dhanasekaran SELVAMUTHUKUMARAN Shaji SIDNEY Department of Ocean Engineering Indian Institute of TechnologyMadras Chennai 600036 India Department of Mechanical Engineering Bannari Amman Institute ofTechnology TamilNadu 638401 India

To convert wave energy into usable forms of energy by utilizing heaving body, heaving bodies （buoys） which are buoyant in nature and float on the water surface are usually used. The wave exerts excess buoyancy force on the buoy, lifting it during the approach of wave crest while the gravity pulls it down during the wave trough. A hydraulic, direct or mechanical power takeoff is used to convert this up and down motion of the buoy to produce usable forms of energy. Though using a floating buoy for harnessing wave energy is conventional, this device faces many challenges in improving the overall conversion efficiency and survivability in extreme conditions. Up to the present, no studies have been done to harness ocean waves using a non-floating object and to find out the merits and demerits of the system. In the present paper, an innovative heaving body type of wave energy converter with a non-floating object was proposed to harness waves. It was also shown that the conversion efficiency and safety of the proposed device were significantly higher than any other device proposed with floating buoy. To demonstrate the improvements, experiments were conducted with non- floating body for different dimensions and the heave response was noted. Power generation was not considered in the experiment to observe the worst case response of the heaving body. The device was modeled in artificial neural network （ANN）, the heave response for various parameters were predicted, and compared with the experimental results. It was found that the ANN model could predict the heave response with an accuracy of 99%.

关键词： ocean wave energy point absorbers heaving body non-floating object heave response ratio artificial neural network (ANN)

Mutual Self‑Regulation of d‑Electrons of Single Atoms and Adjacent Nanoparticles for Bifunctional Oxygen Electrocatalysis and Rechargeable Zinc‑Air Batteries

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Nano-Micro Letters 2023年第4期15卷 40-57页

作者： Sundaram chandrasekaran Rong Hu Lei Yao Lijun Sui Yongping Liu Amor Abdelkader Yongliang Li Xiangzhong Ren Libo Deng College of Chemistry and Environmental Engineering Shenzhen UniversityShenzhen 518060People’s Republic of China College of Chemistry and Bioengineering Guilin University of TechnologyGuilin 541004People’s Republic of China Shenzhen Key Laboratory of Special Functional Materials Shenzhen Engineering Laboratory for Advanced Technology of CeramicsCollege of Materials Science and EngineeringGuangdong Research Center for Interfacial Engineering of Functional MaterialsShenzhen UniversityShenzhen 518060People’s Republic of China Shanghai Key Laboratory for R&D and Application of Metallic Functional Materials Institute of New Energy for VehiclesSchool of Materials Science and EngineeringTongji UniversityShanghai 201804People’s Republic of China Department of Design and Engineering Faculty of Science&TechnologyBournemouth UniversityPoole BH125BBDorsetUK

Rechargeable zinc-air batteries(ZABs)are a promising energy conversion device,which rely critically on electrocatalysts to accelerate their rate-determining reactions such as oxygen reduction(ORR)and oxygen evolution reactions(OER).Herein,we fabricate a range of bifunctional M-N-C(metal-nitrogen-carbon)catalysts containing M-Nx coordination sites and M/MxC nanoparticles(M=Co,Fe,and Cu)using a new class ofγ-cyclodextrin(CD)based metal-organic framework as the *** the two types of active sites interacting with each other in the catalysts,the obtained Fe@C-FeNC and Co@C-CoNC display superior alkaline ORR activity in terms of low half-wave(E1/2)potential(~0.917 and 0.906 V,respectively),which are higher than Cu@C-CuNC(~0.829 V)and the commercial Pt/C(~0.861 V).As a bifunctional electrocatalyst,the Co@C-CoNC exhibits the best performance,showing a bifunctional ORR/OER overpotential(ΔE)of~0.732 V,which is much lower than that of Fe@C-FeNC(~0.831 V)and Cu@C-CuNC(~1.411 V),as well as most of the robust bifunctional electrocatalysts reported to *** X-ray absorption spectroscopy and density functional theory simulations reveal that the strong electronic correlation between metallic Co nanoparticles and the atomic Co-N4 sites in the Co@C-CoNC catalyst can increase the d-electron density near the Fermi level and thus effectively optimize the adsorption/desorption of intermediates in ORR/OER,resulting in an enhanced bifunctional electrocatalytic *** Co@C-CoNC-based rechargeable ZAB exhibited a maximum power density of 162.80 mW cm^(−2) at 270.30 mA cm^(−2),higher than the combination of commercial Pt/C+RuO2(~158.90 mW cm^(−2) at 265.80 mA cm^(−2))*** the galvanostatic discharge at 10 mA cm^(−2),the ZAB delivered an almost stable discharge voltage of 1.2 V for~140 h,signifying the virtue of excellent bifunctional ORR/OER electrocatalytic activity.

关键词： Cyclodextrin CD-MOF Single-atom catalyst ORR/OER Zinc-air battery

The effect of annealing temperature and the characteristics of p-n junction diodes based on sprayed polyaniline/ZnO thin films

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Journal of Semiconductors 2013年第8期34卷 19-24页

作者： R.Suresh V.Ponnuswamy J.chandrasekaran D.Manoharan R.Mariappan Department of Physics Sri Ramakrishna Mission Vidyalaya College of Arts and ScienceCoimbatore-641020Tamil NaduIndia

Polyaniline,ZnO and polyaniline/ZnO nanocomposite thin films are coated on glass substrates using the spray pyrolysis *** samples are characterized by the XRD,SEM,EDAX,UV-Vis and I-V characteristics. The XRD analyses confirm that the spray-coated polyaniline and ZnO thin films have orthorhombic and hexagonal structures,respectively,and optical bandgap energy decreases from 3.81 to 3.41 eV with the addition of a Zn *** analysis of the polyaniline/ZnO nanocomposite thin films shows that there is an agglomeration of ZnO particles with uniform distribution in the polyaniline matrix,and the diode characteristics of the polyaniline /ZnO nanocomposite show weak rectification *** such as the ideality factor,reverse saturation current and barrier height are calculated from the I-V characteristics.

关键词： thin films X-ray diffraction optical properties I-V characteristics

ARGUS: Interactive visual analysis of disruptions in smartphone-detected Bio-Behavioral Rhythms

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Visual Informatics 2021年第3期5卷 39-53页

作者： Hamid Mansoor Walter Gerych Abdulaziz Alajaji Luke Buquicchio Kavin chandrasekaran Emmanuel Agu Elke Rundensteiner Worcester Polytechnic Institute USA

Human Bio-Behavioral Rhythms(HBRs)such as sleep-wake cycles(Circadian Rhythms),and the degree of regularity of sleep and physical activity have important health *** devices such as smartphones can sense HBRs by continuously analyzing data gathered passively by built-in sensors to discover important clues about the degree of regularity and disruptions in behavioral *** human behavior is complex and smartphone data is voluminous with many channels(sensor types),it can be challenging to make meaningful observations,detect unhealthy HBR deviations and most importantly pin-point the causes of *** work has largely utilized computational methods such as machine and deep learning approaches,which while accurate,are often not explainable and present few actionable insights on HBR patterns or *** assist analysts in the discovery and understanding of HBR patterns,disruptions and causes,we propose ARGUS,an interactive visual analytics *** a foundation of ARGUS,we design an intuitive Rhythm deviation Score(RDS)that analyzes users’smartphone sensor data,extracts underlying twenty-four-hour rhythms and quantifies their degree of *** score is then visualized using a glyph that makes it easy to recognize disruptions in the regularity of *** also facilitates deeper HBR insights and understanding of causes by linking multiple visualization panes that are overlaid with objective sensor information such as geo-locations and phone state(screen locked,charging),and user-provided or smartphone-inferred ground truth *** array of visualization overlays in ARGUS enables analysts to gain a more comprehensive picture of HBRs,behavioral patterns and deviations from *** design of ARGUS was guided by a goal and task analysis study involving an expert versed in HBR and smartphone *** demonstrate its utility and generalizability,two different datasets were explored using ARGUS and our use ca

关键词： Interactive visual analytics Circadian rhythms Smartphone-sensed data