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Linking electronic structure calculations to generalized stacking fault energies in multicomponent alloys

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npj Computational Materials 2020年第1期6卷 989-997页

作者： Anirudh Raju natarajan Anton Van der Ven Materials Department University of CaliforniaSanta BarbaraCA 93106USA

The generalized stacking fault energy is a key ingredient to mesoscale models of *** we develop an approach to quantify the dependence of generalized stacking fault energies on the degree of chemical disorder in multicomponent *** introduce the notion of a“configurationally-resolved planar fault”(CRPF)energy and extend the cluster expansion method from alloy theory to express the CRPF as a function of chemical occupation variables of sites surrounding the *** apply the approach to explore the composition and temperature dependence of the unstable stacking fault energy(USF)in binary Mo–Nb ***-principles calculations are used to parameterize a formation energy and CRPF cluster *** Carlo simulations show that the distribution of USF energies is significantly affected by chemical composition and *** formalism is broadly applicable to arbitrary crystal structures and alloy chemistries and will enable the development of rigorous models for deformation mechanisms in high-entropy alloys.

关键词： alloy alloys fault

Antimutagenic potential of curcumin on chromosomal aberrations in Allium cepa

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Journal of Zhejiang University-Science B(Biomedicine & Biotechnology) 2007年第7期8卷 470-475页

作者： RAGUNATHAN Irulappan PANNEERSELVAM natarajan Research Centre and Postgraduate Studies in Botany the Madura College Madurai-625 011 Tamil Nadu India

Turmeric has long been used as a spice and food colouring agent in Asia. In the present investigation, the antimutagenic potential of curcumin was evaluated in Allium cepa root meristem cells. So far there is no report on the biological properties of curcumin in plant test systems. The root tip cells were treated with sodium azide at 200 and 300 μg/ml for 3 h and curcumin was given at 5, 10 and 20 μg/ml for 16 h, prior to sodium azide treatment. The tips were squashed after colchicine treatment and the cells were analyzed for chromosome aberration and mitotic index. Curcumin induces chromosomal aberration in Allium cepa root tip cells in an insignificant manner, when compared with untreated control. Sodium azide alone induces chromosomal aberrations significantly with increasing concentrations. The total number of aberrations was significantly reduced in root tip cells pretreated with curcumin. The study reveals that curcumin has antimutagenic potential against sodium azide induced chromosomal aberrations in Allium cepa root meristem cells. In addition, it showed mild cytotoxicity by reducing the percentage of mitotic index in all curcumin treated groups, but the mechanism of action remains unknown. The antimutagenic potential of curcumin is effective at 5 μg/ml in Allium cepa root meristem cells.

关键词：染色体生殖毒性植物学葱属植物

Assessing combined toxic effects of tetracycline and P25 titanium dioxide nanoparticles using Allium cepa bioassay

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Frontiers of Environmental Science & Engineering 2021年第1期15卷 101-112页

作者： Barsha Roy Khushboo Kadam Suresh Palamadai Krishnan Chandrasekaran natarajan Amitava Mukherjee School of Biosciences and Technology VITVellore 632014India Centre for Nanobiotechnology VITVellore 632014India

Usage of titanium dioxide nanoparticles(TiO_(2) NPs)and tetracycline(TC)has increased significantly in the present *** leads to their release and accumulation in the *** the compounds,individually,can have adverse toxic effects on the *** binary mixtures can increase this degree of *** present study aimed to evaluate the toxicity of both the contaminants in individual and binary mixtures in Allium ***,the toxicity of TiO_(2) NPs upon UVA pre-irradiation was also *** showed that UVA pre-irradiated NPs(UVA-TiO_(2) NPs)had a significant decrease in cell viability than their non-irradiated counterparts(NI-TiO_(2)),denoting an increase in photocatalytic activity upon UVA *** low concentrations of TC(EC10=0.016µmol/L)mixed with TiO2 NPs significantly increased the toxicity for both UVA-TiO_(2) and NI-TiO_(2) *** ROS generation was significantly high for UVA-TiO_(2) ***,TC did not have any effects on ROS *** the compounds exhibited genotoxic potential in *** chromosomal abnormalities like anaphase bridges,telophase bridges,laggard chromosomes,binucleate cells,*** *** binary mixture of UVA-TiO_(2) NPs and TC showed the highest chromosomal aberrations(64.0%±1.26%)than the mixture with NI-TiO_(2) or the individual *** decreased significantly after recovery(46.8%±1.92%),denoting the self-repair *** study proved that UVA-TiO2 NPs were more toxic and could be enhanced further when mixed with a sub-lethal concentration of *** work will help to assess the risk of both compounds in the environment.

关键词： Binary toxicity Cell viability Mitotic index Chromosomal aberration Reactive oxygen species Nanoparticles internalization

Analysis of EMD Algorithm for Identification and Extraction of An Acoustic Signal in Underwater Channel Against Wind Driven Ambient Noise

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China Ocean Engineering 2014年第5期28卷 645-657页

作者： S.Sakthivel MURUGAN V.natarajan K.MAHESWARAN ECE Department SSN College of Engineering Instrumentation Department MIT Campus Anna University Infosys Chennai India

Sonar generated acoustic signals transmitted in underwater channel for distant communications are affected by numerous factors like ambient noise, making them nonlinear and non-stationary in nature. In recent years, the application of Empirical Mode Decomposition(EMD) technique to analyze nonlinear and non-stationary signals has gained much attention. It is an empirical approach to decompose a signal into a set of oscillatory modes known as intrinsic mode functions(IMFs). In general, Hilbert transform is used in EMD for the identification of oscillatory signals. In this paper a new EMD algorithm is proposed using FFT to identify and extract the acoustic signals available in the underwater channel that are corrupted due to various ambient noises over a range of 100 Hz to 10 kHz in a shallow water region. Data for analysis are collected at a depth of 5 m and 10 m offshore Chennai at the Bay of Bengal. The algorithm is validated for different sets of known and unknown reference signals. It is observed that the proposed EMD algorithm identifies and extracts the reference signals against various ambient noises. Significant SNR improvement is also achieved for underwater acoustic signals.

关键词： EMD IMF SNR ambient noises underwater acoustic signals FFT

Optimization of Performance and Emission Characteristics of PPCCI Engine fuelled with Ethanol and Diesel blends Using Grey-Taguchi Method

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Journal of Thermal Science 2018年第1期27卷 89-94页

作者： S.natarajan K.Pitchandi N.V.Mahalakshmi Department of Mechanical Engineering Sri Venkateswara College of EngineeringSriperumbudur-602117TamilnaduIndia. Department of Mechanical Engineering Sri Venkatcswara College of EngineeringSriperumbudur-602117TamilnaduIndia. Internal combustion Engineering Division Department of Mechanical EngineeringCollege of EngineeringAnna UniversityChennai-600025TamilnaduIndia.

The performance and emission characteristics of a PPCCI engine fuelled with ethanol and diesel blends were carried out on a single cylinder air cooled CI engine. In order to achieve the optimal process response with a limited number of experimental cycles, multi objective grey relational analysis had been applied for solving a multiple response optimization problem. Using grey relational grade and signal-to-noise ratio as a performance index, a combination of input parameters was prefigured so as to achieve optimum response characteristics. It was observed that 20% premixed ratio of blend was most suitable for use in a PPCCI engine without significantly affecting the engine performance and emissions characteristics.

关键词：排放特征优化问题柴油机引擎乙醇性能反应特征输入参数

In situ formation of bimetallic FeNi nanoparticles on sand through green technology:Application for tetracycline removal

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Frontiers of Environmental Science & Engineering 2020年第1期14卷 185-197页

作者： Ravikumar KVG Debayan Ghosh M rudula Pulimi Chandrasekaran natarajan Amitava Mukherjee Centre for Nanobiotechnology VITVelloreTamil NaduIndia

In this study,FeNi nanoparticles were green synthesized using Punica granatum(pomegranate)peel extract,and these nanoparticles were also formed in situ over quartz sand(GS-FeNi)for removal of tetracycline(TC).Under the optimized operating conditions,(GS-FeNi concentration:1.5%w/v;concentration of TC:20 mg/L;interaction period:180 min),99±0.2%TC removal was achieved in the batch reactor The removaT capacity was 181±1 mg/g.A detailed characterization of the sorbent and the solution before and after the interaction revealed that the removal mechanism(s)involved both the sorption and degradation of *** reusability of reactant was assessed for four cycles of operation,and 77±4%of TC removal was obtained in the *** judge the environmental sustainability of the process,residual toxicity assay of the interacted TC solution was performed with indicator bacteria(Bacillus and Pseudomonas)and algae(Chlorella sp.),which confirmed a substantial decrease in the *** continuous column studies were undertaken in the packed bed reactors using *** the optimized conditions,quite high removal efficiency(978±5 mg/g)was obtained in the *** application of GS-FeNi for antibiotic removal was further evaluated in lake water,tap water,and ground water spiked with TC,and the removal capacity achieved was found to be 781±5,712±5,and 687±3 mg/g,*** work can pave the way for treatment of antibiotics and other pollutants in the reactors using novel green composites prepared from fruit wastes.

关键词： GS-FeNi nanoparticles Tetracycline removal Re-usability Residual toxicity Column studies

Recent advances based on the synergetic effect of adsorption for removal of dyes from waste water using photocatalytic process

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Journal of Environmental Sciences 2018年第3期30卷 201-222页

作者： Subramanian natarajan Hari C.Bajaj Rajesh J.Tayade Inorganic Materials and Catalysis Division (IMCD) CSIR-Central Salt and Marine Chemicals Research Institute (CSIR-CSMCRI)Council of Scientific and Industrial Research (CSIR)

The problem of textile dye pollution has been addressed by various methods,mainly physical,chemical,biological,and *** methods mainly separate and/or remove the dye present in ***,advanced oxidation processes（AOP）have been focused for removal of dye from waste water due to their advantages such as ecofriendly,economic and capable to degrade many dyes or organic pollutant present in *** is one of the advance oxidation processes,mainly carried out under irradiation of light and suitable photocatalytic *** photocatalytic activity of the photocatalytic materials mainly depends on the band gap,surface area,and generation of electron–hole pair for degradation dyes present in *** has been observed that the surface area plays a major role in photocatalytic degradation of dyes,by providing higher surface area,which leads to the higher adsorption of dye molecule on the surface of photocatalyst and enhances the photocatalytic *** present review discusses the synergic effect of adsorption of dyes on the photocatalytic efficiency of various nanostructured high surface area *** addition,it also provides the properties of the water polluting dyes,their mechanism and various photocatalytic materials;and their morphology used for the dye degradation under irradiation of light along with the future prospects of highly adsorptive photocatalytic material and their application in photocatalytic removal of dye from waste water.

关键词： Photocatalysis Dye degradation Adsorption Water pollution Advanced oxidation processes Nanomaterials

Evolution of fracture permeability due to co-colloidal bacterial transport in a coupled fracture-skin-matrix system

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Geoscience Frontiers 2012年第4期3卷 503-514页

作者： N.natarajan G.Suresh Kumar EWRE Division Department of Civil EngineeringIndian Institute of TechnologyMadrasChennai 600036India Department of Ocean Engineering Indian Institute of TechnologyMadrasChennai 600036India

A numerical model is developed for investigating the evolution of fracture permeability in a coupled fracture-matrix system in the presence of fracture-skin with simultaneous colloidal and bacte- rial transport, by taking into account the effects of thermal stress and silica precipitation/dissolution, which is computed using linear reaction kinetics. The non-linear coupled equations are numerically modeled using the fully implicit finite difference method and a constant continuous source is adopted while modeling thermal, contaminant, colloidal and bacterial transport. Due to co-colloid bacterial trans- port under non-isothermal conditions, in a coupled fracture-skin-matrix system, the fracture apertures vary spatially, with a corresponding pressure variation for a constant discharge. A series of numerical experiments were conducted for analyzing the spatial variation of fracture aperture in response to the combined effects of thermal stress, silica precipitation/dissolution, and simultaneous colloidal and bacte- rial transport in the presence of the fracture-skin. The simulation results suggest that temperature and contaminant concentration of the mobile fluid within the fracture increases with reduction in initial frac- ture aperture. The pattern of variation followed by the fracture aperture is nearly the same in the presence and absence of bacterial transport but the magnitude of the fracture aperture is low under the influence of bacterial transport. The variation in the fracture aperture resulting from precipitation-dissolution and thermoelastic stress is significant when the fracture aperture is very low and reduces with increment in fracture aperture. The variation in fracture aperture and pressure remains the same for both undersaturated and supersaturated fluid entering the fracture due to the influence of bacterial transport at the inlet of the fracture.

关键词： Bacterial transport Colloidal transport Fracture permeability Fracture skin Precipitation-dissolution

In vitro biofilm formation by uropathogenic Escherichia coli and their antimicrobial susceptibility pattern

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Asian Pacific Journal of Tropical Medicine 2012年第3期5卷 210-213页

作者： Poovendran Ponnusamy Vidhya natarajan Murugan Sevanan Department of Microbiology Dr.N.G.P Arts and Science CollegeCoimbatore-641048Tamil NaduIndia Department of Biotechnology School of Biotechnology and Health SciencesKarunya UniversityCoimbatore-641114Tamil NaduIndia

Objective:To detect in vitro biofilm formation of uropathogenic Escherichia coli(***)(UPEC) strains isolated from urine specimens and also to determine their antimicrobial susceptibility pattern using 13 commonly used ***:The present study comprised of 166 urine specimens collected from tertiary care hospitals in and around *** India. All the specimens were subjected to gram staining,bacterial culture and the *** strains were screened for biofilm formation using Tube Method(TM),Congo Red Agar(CRA) and Tissue Culture Plate method(TCP) ***,the antimicrobial susceptibility test was performed by Kirby Bauer-disk diffusion method for the biofilm and non-biofilm producing E. coli ***:Of the 100(60.2%) *** strains,72 strains displayed a biofilm positive phenotype under the optimized conditions in the Tube Method and the strains were classified as highly positive(17,23.6%),moderate positive(19.26.3%) and weakly positive(36.50.0%). similarly under the optimized conditions on Congo Red agar medium,biofilm positive phenotype strains were classified as highly positive(23,23%).moderate positive(37.37%) and weakly positive(40,40%).While in TCP method,the biofilm positive phenotype strains were also classified as highly positive(6.6%),moderate positive(80.80%) and weakly positive(14,14%),it didn’t not correlate well with the tube method for detecting biofilm formation in *** rates of antibiotic resistance of biofilm producing *** were found to be 100%for chloramphenicol and amoxyclav(amoxicillin and clavulanic acid),86%for gentamicin and cefotaxime.84%for ceftazidime,83%for cotrimoxazole and piperacillin/tazobactam,75%for tetracycline and 70% for amikacin,Conclusions:This study reveals the prevalence and antimicrobial susceptibility pattern of biofilm and non-biofilm producing uropathogenic *** strains.

关键词： Urinary tract infection Escherichia coli biofilm Multi-drug resistance