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High-yield synthesis and liquid-exfoliation of two- dimensional belt-lik. hafnium disulphide

Nano Research 2018年第1期11卷 343-353页

作者： Harneet k.ur Sandeep Yadav avanish k. srivastava Nidhi Singh Shyama Rath Jorg J. Schneider Om P. Sinha Ritu srivastava National Physical Laboratory Council of Scientific and Industrial Research Dr. K. S. Krishnan Road New Delhi I I O012 India Academy of Scientific and Innovative Research NPL New Delhi 110012 India Technische Universitat Darmstadt Eduard-ZintMnstitut f~r Anorganische und Physikalische Chemie 12 105 117 Alarich-Weiss-Str 12 64287 Darmstadt Germany DepartmentofPhysics andAstrophysics University of Delhi Delhi 110007 India Amity Institute of Nanotechnology Amity University UP Sector 125 Noida Uttar Pradesh 201313 India

Producing environmentally stable monolayers and few-layers of hafnium disulphide （HfS2） with a high yield to reveal its unlock.d electronic and optoelectronic applications is still a challenge. HfS2 is a layered two-dimensional material of group-IV transition metal dichalcogenides. For the first time, we demonstrate a simple and cost-effective method to grow layered belt-lik. nanocrystals of HfS2 with a notably large interlayer spacing followed by their chemical exfoliation. Various microscopic and spectroscopic techniques confirm that these as-grown crystals exfoliate into single or multiple layers in a few minutes using solvent assisted ultrasonification method in N-cyclohexyl-2- pyrrolidone. The exfoliated nanosheets of HfS2 exhibit an indirect bandgap of 1.3 eV with high stability against surface degradation. Furthermore, we demonstrate that these nanosheets hold potential for electronic applications by fabricating a field-effect transistor based on few-layered HfS2, exhibiting a field-effect mobility of 0.95 cm2/（V.s） with a high on/off current modulation ratio of 10,000 in ambient conditions. The method is scalable and has a potential significance for both academic and industrial purposes.

关键词： two-dimensionalmaterials hafnium disulphide nano-crystals liquid-phase exfoliation environment-stabili~ field-effect transistor

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Survival, development and life tables of two congeneric ladybirds in aphidophagous guilds

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Insect Science 2006年第2期13卷 119-126页

作者： avanish k. GUPTA SHEFALI srivastava GEETANJALI MISHRA k.LPANA SINGH OMk.R Ladybird Research Laboratory Department of Zoology University of Lucknow Lucknow India

Two congeneric aphidophagous ladybirds, Coccinella septempunctata and Coccinella transversalis, were reared on three aphid species, Lipaphis erysimi, Myzus persicae and Aphis nerii, to estimate the effect of prey quality and intra- and interspecific interactions on their survival and development of life stages. Mortality of first instar ladybirds of both species was highest feeding on A. nerii. Preimaginal mortafity was lowest when feeding on L. erysimi （C. septempunctata, 1.6% and C. transversalis, 3.2%）, and highest when feeding on A. nerii （ C. septempunctata, 6.2% and C. transversalis, 8.2%）. Comparatively higher weight and larger size of C. septempunctata along with the lower levels of mortality recorded suggested that it is more lik.ly to have acted as an intraguild predator than C. transversalis. High recorded mortality of C. transversalis is attributed to probable intraguild predation on account of its smaller size. The major sources of mortality were probably cannibalism, intraguild predation and other unk.own factors. Lower prey quality increased the incidence of cannibalism and intraguild predation, especially in C. transversalis. The investigation suggests an intrinsic competitive advantage for C. septempunctata over C. transversalis in guilds of three aphid species.

关键词： Coccinella septempunctata Coccinella transversalis ladybirds life table,aphids cannibalism intraguild predation

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Growth of Boron Nitride Nanotubes Having Large Surface Area Using Mechanothermal Process

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World Journal of Nano Science and Engineering 2011年第4期1卷 119-128页

作者： Sunil k. Singhal avanish k. srivastava Rak.sh B. Mathur 不详

Nanostructures of boron nitride (BN) including nanotubes, nanofibers and nanosheets having a large surface area are very useful in storing hydrogen and other gases. In the present paper we report the synthesis and characterization of these nanostructures of BN using mechanothermal process. Under this process elemental boron powder is first ball milled to about 50 h in an inert atmosphere and then annealed at 1100℃ - 1250℃ for 6 h in the presence of NH3 gas. By this treatment nanotubes and other nanostructures of BN were synthesized. The diameter of BN nanotubes varied from 20 to 50 nm and most of them exhibited spindle or bamboo lik. morphology. Because of the large surface area, these nanotubes may be explored for a better hydrogen gas storage device as compared to the crystallized nanotubes. The main advantage of this technique is that the nanotubes can be grown in large quantity. A possible growth mechanism towards the evolution of such fascinating nano-objects of boron nitride has been discussed employing high-resolution transmission electron microscopy and photoluminescence.

关键词： Boron Nitride Nanotubes Mechanothermal Process Morphology Photo Luminescence

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Electrochemical Impedance Analysis of Biofunctionalized Conducting Polymer-Modified Graphene-CNTs Nanocomposite for Protein Detection

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Nano-Micro Letters 2017年第1期9卷 104-112页

作者： Shobhita Singal avanish k.srivastava Rajesh CSIR-National Physical Laboratory Dr.K.S.Krishnan RoadNew Delhi 110012India Academy of Scientific and Innovative Research(AcSIR) CSIR-National Physical LaboratoryDr.K.S.Krishnan RoadNew Delhi 110012India

We report an electrodeposited poly(pyrrole-co-pyrrolepropylic acid) copolymer modified electroactive graphene-carbon nanotubes composite deposited on a glassy carbon electrode to detect the protein antigen(cTnI). The copolymer provides pendant carboxyl groups for the site-specific covalent immobilization of protein antibody, antitroponin I. The hybrid nanocomposite was used as a transducer for biointerfacial impedance sensing for cTnI *** results show that the hybrid exhibits a pseudo capacitive behaviour with a maximum phase angle of 49° near 1 Hz,which is due to the inhomogeneous and porous structure of the hybrid composition. The constant phase element of copolymer is 0.61(n = 0.61), whereas, it is 0.88(n = 0.88) for the hybrid composites, indicating a comparatively homogeneous microstructure after biomolecular functionalization. The transducer shows a linear change in charge transfer characteristic(R_(et)) on cTnI immunoreaction for spik.d human serum in the concentration range of 1.0 pg mL^(-1)–10.0 ng mL^(-1). The sensitivity of the transducer is 167.8 ± 14.2 Ω cm^2 per decade, and it also exhibits high specificity and good reproducibility.

关键词： Conducting polymer Graphene Carbon nanotube Hybrid Transducer Protein antigen cTnI Electrochemical impedance

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Next-Generation Intelligent MXene-Based Electrochemical Aptasensors for Point-of-Care Cancer Diagnostics

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Nano-Micro Letters 2022年第6期14卷 248-281页

作者： Arpana Parihar Ayushi Singhal Neeraj k.mar Raju k.an MohdAk.am k.an avanish k.1} Industrial Waste Utilization Nano and BiomaterialsCSIR-Advanced Materials and Processes Research Institute(AMPRI)Hoshangabad RoadBhopal 462026MPIndia Academy of Scientific and Innovative Research(AcSIR) Ghaziabad 201002India

Delayed diagnosis of cancer using conventional diagnostic modalities needs to be addressed to reduce the mortality rate of ***,2 D nanomaterial-enabled advanced biosensors have shown potential towards the early diagnosis of *** high surface area,surface functional groups availability,and excellent electrical conductivity of MXene mak. it the 2 D material of choice for the fabrication of advanced electrochemical biosensors for disease ***-enabled electrochemical aptasensors have shown great promise for the detection of cancer biomark.rs with a femtomolar limit of ***,the stability,ease of synthesis,good reproducibility,and high specificity offered by MXene-enabled aptasensors hold promise to be the mainstream diagnostic *** this review,the design and fabrication of MXene-based electrochemical aptasensors for the detection of cancer biomark.rs have been ***,various synthetic processes and useful properties of MXenes which can be tuned and optimized easily and efficiently to fabricate sensitive biosensors have been ***,futuristic sensing applications along with challenges will be deliberated herein.

关键词： MXene Electrochemical devices POCT Aptamer Cancer diagnostics

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Modification at Lattice Scale for an Optimized Optical Response of Al<sub>x</sub>(ZnO)<sub>1-x</sub>Nanostructures

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World Journal of Nano Science and Engineering 2011年第1期1卷 15-19页

作者： avanish k.mar srivastava k.ruppanan Senthil Melepurath Deepa Ruchi Gak.ar Jai Shank.r Tawale 不详

We report the systematic changes of nano-scaled features and optical properties in a promising transparent oxide material, namely, Alx (x = 0, 1, 2 and 5%) doped ZnO1-x (AZO). Electron microscopy investigations revealed the alterations at lattice scale depending on the presence of Al-content in ZnO nanostructures. Lattice spacings of 0.26 and 0.28 nm oriented along the (0002) and (10 0) planes, respectively, were attributed to euhedral-and facetted-structures of hexagonal-ZnO. The AZO samples were further characterized by XRD, SEM, UV-vis spectrophotometry, Raman spectroscopy and photoluminescence studies. It has been shown that at a dopant concentration of 2%Al in ZnO, an optimal balance could be achieved between microstructure and optical properties.

关键词： Electron Microscopy Nanostructures ZnO Photoluminescence

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