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Varrla Eswaraiah

Bio: Varrla Eswaraiah is an academic researcher from Indian Institute of Technology Madras. The author has contributed to research in topics: Graphene & Graphite oxide. The author has an hindex of 10, co-authored 13 publications receiving 1508 citations. Previous affiliations of Varrla Eswaraiah include Nanyang Technological University.

Papers
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TL;DR: The improvement in FC, AW, and EP properties of nanofluids is respectively by 80, 33, and 40% compared with base oil and can be attributed to the nanobearing mechanism of graphene in engine oil and ultimate mechanical strength of graphene.
Abstract: Ultrathin graphene (UG) has been prepared by exfoliation of graphite oxide by a novel technique based on focused solar radiation. Graphene based engine oil nanofluids have been prepared and their frictional characteristics (FC), antiwear (AW), and extreme pressure (EP) properties have been evaluated. The improvement in FC, AW, and EP properties of nanofluids is respectively by 80, 33, and 40% compared with base oil. The enhancement can be attributed to the nanobearing mechanism of graphene in engine oil and ultimate mechanical strength of graphene.

362 citations

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TL;DR: In this article, a novel foam composites comprising functionalized graphene (f-G) and polyvinylidene fluoride (PVDF) were prepared and electrical conductivity and electromagnetic interference (EMI) shielding efficiency of the composites with different mass fractions of f-G have been investigated.
Abstract: Novel foam composites comprising functionalized graphene (f-G) and polyvinylidene fluoride (PVDF) were prepared and electrical conductivity and electromagnetic interference (EMI) shielding efficiency of the composites with different mass fractions of f-G have been investigated. The electrical conductivity increases with the increase in concentration of f-G in insulating PVDF matrix. A dramatic change in the conductivity is observed from 10−16 S · m−1 for insulating PVDF to 10−4 S · m−1 for 0.5 wt.% f-G reinforced PVDF composite, which can be attributed to high-aspect-ratio and highly conducting nature of f-G nanofiller, which forms a conductive network in the polymer. An EMI shielding effectiveness of ≈20 dB is obtained in X-band (8–12 GHz) region and 18 dB in broadband (1–8 GHz) region for 5 wt.% of f-G in foam composite. The application of conductive graphene foam composites as lightweight EMI shielding materials for X-band and broadband shielding has been demonstrated and the mechanism of EMI shielding in f-G/PVDF foam composites has been discussed.

351 citations

Journal ArticleDOI
01 Jul 2016-Small
TL;DR: Recent advances in the synthesis, fabrication, anisotropic physical properties, and BP-based devices including field effect transistors (FETs) and photodetectors, are discussed.
Abstract: Black phosphorus (BP) is an emerging two-dimensional (2D) material with a natural bandgap, which has unique anisotropy and extraordinary physical properties. Due to its puckered structure, BP exhibits strong in-plane anisotropy unlike other layered materials. The bandgap tunability of BP enables a wide range of ultrafast electronics and high frequency optoelectronic applications ranging from telecommunications to thermal imaging covering the nearly entire electromagnetic spectrum, whereas no other 2D material has this functionality. Here, recent advances in the synthesis, fabrication, anisotropic physical properties, and BP-based devices including field effect transistors (FETs) and photodetectors, are discussed. Recent passivation approaches to address the degradation of BP, which is one of the main challenges to bring this material into real world applications, are also introduced. Finally, a comment is made on the recent developments in other emerging applications, future outlook and challenges ahead in BP research.

312 citations

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TL;DR: In this article, a real-time strain response of functionalized graphene-polyvinylidene fluoride (f-G-PVDF) nanocomposite films was demonstrated under tensile loads.
Abstract: Functionalized graphene–polyvinylidene fluoride (f-G–PVDF) nanocomposite films were synthesized using a simple solvent casting technique. The investigation demonstrates the real time strain response of f-G–PVDF nanocomposites on the macro-scale under tensile loads and the use of this nanocomposite as strain sensor. This is ascribed to the variation of electrical properties of graphene–polymer upon mechanical deformation at the nanoscale.

178 citations

Journal ArticleDOI
TL;DR: In this paper, the authors report a rapid, chemical free and low temperature method for high throughput production of graphene by exfoliation of graphite oxide using focused solar radiation, which is a simple method of preparation, easy scalability, cost effectiveness and high electrical conductivity of solar graphene hold great promise for true practical applications.
Abstract: Herein we report a rapid, chemical free and low temperature method for high throughput production of graphene by exfoliation of graphite oxide using focused solar radiation. The simple method of preparation, easy scalability, cost effectiveness and high electrical conductivity (1.5 × 103 S m−1) of solar graphene hold great promise for true practical applications.

168 citations


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[...]

08 Dec 2001-BMJ
TL;DR: There is, I think, something ethereal about i —the square root of minus one, which seems an odd beast at that time—an intruder hovering on the edge of reality.
Abstract: There is, I think, something ethereal about i —the square root of minus one. I remember first hearing about it at school. It seemed an odd beast at that time—an intruder hovering on the edge of reality. Usually familiarity dulls this sense of the bizarre, but in the case of i it was the reverse: over the years the sense of its surreal nature intensified. It seemed that it was impossible to write mathematics that described the real world in …

33,785 citations

Journal ArticleDOI
TL;DR: The unique advances on ultrathin 2D nanomaterials are introduced, followed by the description of their composition and crystal structures, and the assortments of their synthetic methods are summarized.
Abstract: Since the discovery of mechanically exfoliated graphene in 2004, research on ultrathin two-dimensional (2D) nanomaterials has grown exponentially in the fields of condensed matter physics, material science, chemistry, and nanotechnology. Highlighting their compelling physical, chemical, electronic, and optical properties, as well as their various potential applications, in this Review, we summarize the state-of-art progress on the ultrathin 2D nanomaterials with a particular emphasis on their recent advances. First, we introduce the unique advances on ultrathin 2D nanomaterials, followed by the description of their composition and crystal structures. The assortments of their synthetic methods are then summarized, including insights on their advantages and limitations, alongside some recommendations on suitable characterization techniques. We also discuss in detail the utilization of these ultrathin 2D nanomaterials for wide ranges of potential applications among the electronics/optoelectronics, electrocat...

3,628 citations

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TL;DR: In this paper, the authors reviewed several key issues for improving the energy densities of supercapacitors and some mutual relationships among various effecting parameters, and challenges and perspectives in this exciting field are discussed.
Abstract: In recent years, tremendous research effort has been aimed at increasing the energy density of supercapacitors without sacrificing high power capability so that they reach the levels achieved in batteries and at lowering fabrication costs For this purpose, two important problems have to be solved: first, it is critical to develop ways to design high performance electrode materials for supercapacitors; second, it is necessary to achieve controllably assembled supercapacitor types (such as symmetric capacitors including double-layer and pseudo-capacitors, asymmetric capacitors, and Li-ion capacitors) The explosive growth of research in this field makes this review timely Recent progress in the research and development of high performance electrode materials and high-energy supercapacitors is summarized Several key issues for improving the energy densities of supercapacitors and some mutual relationships among various effecting parameters are reviewed, and challenges and perspectives in this exciting field are also discussed This provides fundamental insight into supercapacitors and offers an important guideline for future design of advanced next-generation supercapacitors for industrial and consumer applications

1,761 citations

Journal ArticleDOI
Zongping Chen1, Chuan Xu1, Chaoqun Ma1, Wencai Ren1, Hui-Ming Cheng1 
TL;DR: It is believed that high electrical conductivity and connectivity of the conductive fi llers can improve EMI shielding performance.
Abstract: IO N The rapid development of modern electronics packed with highly integrated circuits generates severe electromagnetic radiation, which leads to harmful effects on highly sensitive precision electronic equipment as well as the living environment for human beings. Great effort has been made for the development of high-performance electromagnetic interference (EMI) shielding materials. In addition to high EMI shielding performance, being lightweight and fl exible are two other important technical requirements for effective and practical EMI shielding applications especially in areas of aircraft, aerospace, automobiles, and fast-growing next-generation fl exible electronics such as portable electronics and wearable devices. [ 1 ] Recently, electrically conductive polymer composites have received much attention for EMI shielding applications, [ 1–12 ] because of their light weight, resistance to corrosion, fl exibility, good processability, and low cost compared to the conventional metal-based materials. The EMI shielding effectiveness of the polymer composites depends critically on the intrinsic electrical conductivity, dielectric constant, magnetic permeability, aspect ratio, and content of conductive fi llers. [ 1–12 ] It is believed that high electrical conductivity and connectivity of the conductive fi llers can improve EMI shielding performance. [ 1 , 2 , 4 , 7 , 8 ]

1,621 citations

Journal ArticleDOI
TL;DR: In this paper, the current status of the intrinsic mechanical properties of the graphene-family of materials along with the preparation and properties of bulk graphene-based nanocomposites is thoroughly examined.

1,531 citations