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Facet selective etching of Au microcrystallites

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Nano Research 2015年第9期8卷 2925-2934页

作者： Gangaiah Mettela and giridhar U. Kulkarni Thematic Unit of Excellence on Nanochemistry and Chemistry and Physics of Materials Unit Jawaharlal Nehru Centre for AdvancedScientific Research (JNCASR) Jakkur P.O. Bangalore 560 064 India

High-symmetry crystals exhibit isotropic properties. Inducing anisotropy, e.g., by facet selective etching, is considered implausible in face-centered cubic （FCC） metals, particularly gold, which, in addition to being an FCC, is noble. We report for the first time the facet selective etching of Au microcrystals obtained in the form of cuboctahedra and pentagonal rods from the thermolysis of a gold- organic precursor. The selective etching of {111} and {100} facets was achieved using a capping method in which tetraoctylammonium cations selectively cap the {111} facets while Br- ions protect the {100} facets. The exposed facets are oxidized by O2/C1-, yielding a variety of interesting geometries. The facet selective etching of the Au microcrystallites is governed only by the nature of the facets; the geometry of the microcystallite does not appear to play a significant role. The etched surfaces appear rough, but a closer examination reveals well-defined corrugations that are indexable to high hkl values. Such surfaces exhibit enhanced Raman activity.

关键词： gold,microcrystallites,facet selective eapping

Micro- and Nanostripes of Self-Assembled Au Nanocrystal Superlattices by Direct Micromolding

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Nano Research 2010年第8期3卷 537-544页

作者： Boya Radha giridhar U.Kulkarni Chemistry and Physics of Materials Unit and DST Unit on Nanoscience Jawaharlal Nehru Centre for Advanced Scientific ResearchJakkur P.O.Bangalore 560064India

A simple,inexpensive direct micromolding method for patterning Au nanocrystal superlattices using a polydimethylsiloxane(PDMS)stamp has been *** method involves in situ synthesis of Au(I)dodecanethiolate and its decomposition leading to Au nanocrystals in the microchannels of the stamp which order themselves to form patterned superlattice stripes,in conformity with the stamp *** to its insolubility in common solvents,the dodecanethiolate was made by reacting Au(PPh3)Cl and dodecanethiol in situ inside the microchannels,by injecting first the former solution in toluene at room temperature followed by the thiol solution at 120°*** the reaction mixture at 250°C,resulted in formation of nanocrystals(with a mean diameter of 7.5 nm)and hexagonal *** using an external pressure while molding,parallel stripes with sub-100 nm widths were *** choice of parameters such as injection temperature of the thiol and concentrations is shown to be important if an ordered superlattice is to be *** addition,these parameters can be varied as a means to control the nanocrystal size.

关键词： nanolithography soft lithography metal nanocrystal superlattice micromolding direct patterning

Electrocondensation and Evaporation of Attoliter Water Droplets: Direct Visualization Using Atomic Force Microscopy

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Nano Research 2010年第5期3卷 307-316页

作者： Narendra Kurra Adina Scott giridhar U.Kulkarni Chemistry and Physics of Materials Unit and DST Unit on Nanoscience Jawaharlal Nehru Centre for Advanced Scientific ResearchJakkur POBangalore 560064India Birck Nanotechnology Center Purdue UniversityWest LafayetteIndiana 47907USA

Working with a biased atomic force microscope(AFM)tip in the tapping mode under ambient atmosphere,attoliter(10^(-18) L)water droplet patterns have been generated on a patterned carbonaceous *** is essentially electrocondensation of water leading to charged droplets,as evidenced from electrostatic force microscopy *** droplets are unusual in that they exhibit a highly corrugated surface and evaporate rather slowly,taking several tens of minutes.

关键词： Electrocondensation attoliter water droplets biased atomic force microscope(AFM)lithography electron beam induced deposition carbonaceous deposition

Utilization of eye care services among those with unilateral visual impairment in rural South India：Andhra Pradesh Eye Disease Study(APEDS)

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International Journal of Ophthalmology(English edition) 2017年第3期10卷 473-479页

作者： Srinivas Marmamula giridhar Pyda Rohit C Khanna Allen Foster Community Eye Health Research Centre Gullapalli Pratibha Rao International Centre for Advancement of Rural Eye Care L V Prasad Eye Institute Hyderabad 500034 India Brien Holden Eye Research Centre L V Prasad Eye Institute Hyderabad 500034 India Wellcome Trust/DBT India Alliance Fellow L V Prasad Eye Institute Hyderabad 500034 India School of Optometry & Vision Science University of New South Wales Sydney NSW 2052 Australia Brien Holden Institute of Optometry and Vision Science L V Prasad Eye Institute Hyderabad 500034 India

AIM：To report on the utilization of eye care services and its associated factors among those with unilateral visual impairment（VI）in a rural South Indian ***：A population based cross-sectional study was conducted in three districts（Adilabad,Mahbubnagar and West Godavari）in the state of Andhra Pradesh,India.A detailed interview and a comprehensive eye examination were conducted. Those with unilateral VI were asked questions about noticing any change in vision and on utilization of eye care services. The most important reason reported by the participant for not utilizing the services was used for the analysis. Multiple logistic regression models were used to examine the association between noticing a change in vision and socio-demographic variables such as age,gender,education and area of residence,severity and causes of ***：Among the 4456 participants aged ≥16y who were administered the questionnaire,53.2% were women,and 54.7% had no education. Of the 489（11%; 95% CI：10.1-11.9）people with unilateral VI,399（81.6%）participants reported noticing a change in their vision over the last five years but only 136（34.1%）participants had soughteye care consultation. Those who had any education（OR：1.9; 95% CI：1.1-3.2）,had blindness（OR：2.7; 95% CI：1.4-5.2）,and cataract（OR：2.1; 95% CI：1.0-4.3）as a cause of unilateral VI were more like to seek eye care consultations. The most commonly reported reasons for not seeking eye care services were ＂do not have money for eye checkup＂ in 30.7% of the participants followed by ＂do not have a serious problem＂（30.0%）.CONCLUSION：A large proportion of rural population though noticed a change in their vision did not seek eye care due to financial and person-related reasons. Eye care service providers need to address these barriers to enhance the uptake of eye care services among those with unilateral VI.

关键词： unilateral visual impairment socio-demographic variables Andhra Pradesh Eye Disease Study India

Non-FCC rich Au crystallites exhibiting unusual catalytic activity

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Nano Research 2017年第7期10卷 2271-2279页

作者： Gangaiah Mettela Nisha Mammen Joydip Joardar Shobhana Narasimhan giridhar U. Kulkarni Thematic Unit of Excellence on Nanochemistry and Chemistry and Physics of Materials Unit Jawaharlal Nehru Centre for Advanced Scientific Research Jakkur Bangalore 560 064 India Theoretical Sciences Unit Jawaharlal Nehru Centre forAdvanced Scientific Research Jakkur Bangalore 560 064 India IntemationalAdvanced Research Centre for Powder Metallurgy & New Materials Balapur Hyderabad 500 005 India Centre for Nano and Soft Matter Sciences Jalahalli Bangalore 560 013 India

Bipyramidal Au microcrystallites have been synthesized by thermalizing a Au-organic complex in the presence of Ag（I） ions, the latter acting as a shape- directing agent. With a highly corrugated morphology leading to strain-induced non-face-centered cubic （non-FCC） Au phases, the non-FCC portion can be tuned by varying the Ag/Au ratio, as verified by diffraction measurements. For a Ag/Au ratio of 0.34, the non-FCC Au portion was as high as 85%. X-ray microdiffraction and electron diffraction measurements reveal that the non-FCC contribution comes primarily from bipyramids, while other microcrystallites, namely, tetrahexahedrons and hexagrams, host non-FCC phases only at the edges and, to an even lesser extent, at the comers. When used as a catalyst for p-nitrophenol reduction, the non-FCC microcrystallites exhibit a significantly enhanced activity compared to FCC Au, which shows only negligible activity. These results are in accordance with trends in the values of two descriptors of reactivity calculated from first principles： The effective coordination number is found to decrease and the d-band center is found to increase in energy going from the FCC to the non-FCC phases of Au. Our findings contradict the general notion that Au is catalytically active only in nanodimensions and is otherwise inert; in this system, its activity arises from the non-FCC phases.

关键词： Au microcrystallites non-face-centered cubic(non-FCC) phases microbeam X-raydiffraction (XRD) catalysis effective coordinationnumber

Structural build-up model for three-dimensional concrete printing based on kinetics theory

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Frontiers of Structural and Civil Engineering 2024年第7期18卷 998-1014页

作者： Prabhat Ranjan PREM P.S.AMBILY Shankar KUMAR Greeshma giridhar Dengwu JIAO Advanced Materials Laboratory CSIR-Structural Engineering Research CentreChennai 600113India Department of Architecture and Civil Engineering City University of Hong KongHong Kong 999077China

The thixotropic structural build-up is crucial in extrusion-based three-dimensional(3D)concrete *** paper uses a theoretical model to predict the evolution of static and dynamic yield stress for printed *** model employs a structural kinetics framework to create a time-independent constitutive link between shear stress and shear *** model considers flocculation,deflocculation,and chemical hydration to anticipate structural *** reversible and irreversible contributions that occur throughout the build-up,breakdown,and hydration are defined based on the proposed structural ***,detailed parametric studies are conducted to evaluate the impact of model *** is revealed that the proposed model is in good agreement with the experimental results,and it effectively characterizes the structural build-up of 3D printable concrete.

关键词： structural build-up rheology thixotropy 3D printable concrete kinetics theory ultra high performance concrete

Electrodeposition of Al from a 1-butylpyrrolidine-AlCl3 ionic liquid

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Progress in Natural Science:Materials International 2015年第6期25卷 603-611页

作者： giridhar Pulletikurthi Bj?rn B?decker Andriy Borodin Bernd Weidenfeller Frank Endres Institute of Electrochemistry Clausthal University of Technology

The addition of 1-butylpyrrolidine to AlCl3results in the formation of an electrolyte that is suited to Al *** feasibility of electrodepositing Al from the synthesized electrolyte was *** compositions of AlCl3and 1-butylpyrrolidine were prepared for this *** mixtures show a different phase behavior at various compositions of AlCl3and ***,Raman and NMR spectroscopy were employed to characterize the synthesized *** the prepared compositions,1:1.2 mol ratio of 1-butylpyrrolidine:AlCl3and the upper phase of 1:1.3 mol ratio of 1-butylpyrrolidine:AlCl3were found to be suitable for Al electrodeposition at room temperature（RT）.Uniform and thick（ mm thick） layers of Al were obtained on copper at *** deposition occured from the cationic species of AlCl3xLty（where x r 2,y ? 1–2,and L ? 1-butylpyrrolidine） in this *** behavior is contrary to the well investigated classic AlCl3based ionic liquids,where the deposition of Al occurs mainly from anionic Al2 Cl 7ions.

关键词： Aluminium Al cations 1-butylpyrrolidine Ionic liquid Electrodeposition

Movable Au Microplates as Fluorescence Enhancing Substrates for Live Cells

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Nano Research 2010年第10期3卷 738-747页

作者： Boya Radha Mohammed Arif Ranjan Datta Tapas K.Kundu giridhar U.Kulkarni Chemistry and Physics of Materials Unit and DST Unit on Nanoscience Jawaharlal Nehru Centre for Advanced Scientific ResearchJakkur P.O.Bangalore 560064India Molecular Biology and Genetics Unit Jawaharlal Nehru Centre for Advanced Scientific ResearchJakkur P.O.Bangalore 560064India International Centre for Materials Science Jawaharlal Nehru Centre for Advanced Scientific ResearchJakkur P.O.Bangalore 560064India

Hexagonal and triangular Au microplates extending over an area of~12,000μm^(2) with thickness in the range 30-1000 nm have been synthesized using a single step thermolysis of(AuCl_(4))^(-)-tetraoctylammonium bromide complex in *** microplates are self-supporting and can be easily manipulated using a sharp pin,a property which enables them to serve as substrates for living *** microplate surface is non-toxic to living cells and can enhance the fluorescence signal from fluorophores residing within the cell by an order of *** addition,the microplates are smooth and single-crystalline,and ideal as microscopy substrates and molecular *** growth of the microplates in the initial stages is interesting in that they seem to grow perpendicular to the substrate,as evidenced by in situ microscopy.

关键词： Au microplates synthesis cell substrate metal enhanced fluorescence manipulation

A Hybrid Approach for Network Intrusion Detection

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Computers, Materials & Continua 2022年第1期70卷 91-107页

作者： Mavra Mehmood Talha Javed Jamel Nebhen Sidra Abbas Rabia Abid giridhar Reddy Bojja Muhammad Rizwan Department of Computer Science Kinnaird College for WomenLahore54000Pakistan ASET Labs IslamabadPakistan Prince Sattam bin Abdulaziz University College of Computer Science and EngineeringAlkharj11942Saudi Arabia College of Business and Information Systems Dakota State UniversityMadisonUnited States of America

Due to the widespread use of the internet and smart devices,various attacks like intrusion,zero-day,Malware,and security breaches are a constant threat to any organization’s network ***,a Network Intrusion Detection System(NIDS)is required to detect attacks in network *** paper proposes a new hybrid method for intrusion detection and attack *** proposed approach comprises three steps to address high false and low false-negative rates for intrusion detection and attack *** the first step,the dataset is preprocessed through the data transformation technique and min-max ***,the random forest recursive feature elimination method is applied to identify optimal features that positively impact the model’s ***,we use various Support Vector Machine(SVM)types to detect intrusion and the Adaptive Neuro-Fuzzy System(ANFIS)to categorize probe,U2R,R2U,and DDOS *** validation of the proposed method is calculated through Fine Gaussian SVM(FGSVM),which is 99.3%for the binary *** Square Error(MSE)is reported as 0.084964 for training data,0.0855203 for testing,and 0.084964 to validate multiclass categorization.

关键词： Network security intrusion detection system machine learning attacks data mining classification feature selection