Hardeep Kumar; L. Olivi;G. Aquilanti; S. Ghosh; P. Srivastava; D. Kabiraj; D. K. Avasthi
Abstract
A series of FeCo-SiO2 granular films of different FeCo atomic concentration (33-54%) have been prepared by fast atom beam sputtering technique and post-annealed in inert (Ar) and reducing (H2) gas environments. Fe and Co K-edge XANES analysis of as-deposited films indicate that both Fe and Co are present ...
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A series of FeCo-SiO2 granular films of different FeCo atomic concentration (33-54%) have been prepared by fast atom beam sputtering technique and post-annealed in inert (Ar) and reducing (H2) gas environments. Fe and Co K-edge XANES analysis of as-deposited films indicate that both Fe and Co are present mainly in their elemental (Fe 0 , Co 0 ) state. A partial oxidation of Fe and Co is observed, as the FeCo alloy content decreases (54 to 33%) due to reduced particle size. XANES/XAFS analysis shows the formation of FeCo alloy with bcc Fe structure in H2 environment annealed films. The XRD and Raman analysis of Ar environment annealed films suggest the formation of Co3O4 and CoFe2O4 phases. The Ar environment is found not to be effective reducing medium to stabilize the FeCo alloy phase, while H2 environment annealing (450-700 o C) leads to formation of bcc FeCo alloy.
Stoyko Fakirov
Abstract
The main target of this review article is to try to find the reasons for the drastic difference between expected and observed mechanical properties of polymer nanocomposites prepared via blending the matrix and the nano-reinforcement. Additional target is to recommend thereafter ways for solving of this ...
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The main target of this review article is to try to find the reasons for the drastic difference between expected and observed mechanical properties of polymer nanocomposites prepared via blending the matrix and the nano-reinforcement. Additional target is to recommend thereafter ways for solving of this problem. Based on the published materials the conclusion is drawn that the main reason for this discrepancy is the poor dispersion resulting in formation of particles with sizes in the micrometer but not in nanometre range. For this reason, it is assumed further that these nanocomposites hardly exist. Since currently are missing techniques and instrumentation for a proper dispersion of the reinforcement to single nanoparticles, it is recommended to avoid the dispersion step during manufacturing of polymer nanocomposites. Two techniques are described for this purpose, representing application of the rather new concept of “converting instead of adding” for preparation of polymer nanocomposites. Copyright © 2018 VBRI Press.
Velram Balaji Mohan; Manfred Stamm;Debes Bhattacharyya; Dongyan Liu; Krishnan Jayaraman
Abstract
This article focuses on the reduction of graphene oxides using different reductants and conditions systematically varying the chemical and physical structure, surface topography and chemistry and film thickness of reduced graphene oxide (rGO) films, with a focus on how these influence the property of ...
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This article focuses on the reduction of graphene oxides using different reductants and conditions systematically varying the chemical and physical structure, surface topography and chemistry and film thickness of reduced graphene oxide (rGO) films, with a focus on how these influence the property of most interest: electrical conductivity. The reduction process restores graphene oxide to a graphene-like structure, improving electrical conductivity while creating changes such as increased roughness, film thickness and new surface functionality. Films with smooth surfaces and minimal thicknesses have been shown to possess higher electrical conductivity. There have been minor changes in d-spacing and improvements in crystal perfection and orientation could be concluded from XRD patterns. Through XPS analysis, a significant decrease in the amount of oxygen functional groups at the surface has been noticed as the films get thinned.
Ganna Ungur; Jakub Hruza
Abstract
This research describes the fabrication of nanofibrous materials for the air purification with high filtration efficiency and catalytic properties to clean the air from solid particles and emissions of automobile's transport. The polyurethane (PU) nanofibers were modified by particles of SnO2 and ...
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This research describes the fabrication of nanofibrous materials for the air purification with high filtration efficiency and catalytic properties to clean the air from solid particles and emissions of automobile's transport. The polyurethane (PU) nanofibers were modified by particles of SnO2 and CrO2 in the ratio 95/5 to impart catalytic properties in the reaction with emission gases (CO, NOx).The modification process was provided by the introduction of metal’s oxide’s particles of different concentrations (1;2; 3; 4%) into the polymer solution. Reological properties and conductivity of the modified solutions were studied. The viscosity of solutions grew up gradually with increasing of SnO2/CrO2 concentrations. Fiber's samples were produced from modified solutions by the electorstatic fiber forming using Nanospider technology. The morphology of produced fibers was analysed by the Scanning Electron Microscopy (SEM). SEM pictures confirmed the smoothness of fibrous layer. The diameters of fibres were measured with the help of Lucie 32G computer software. The obtained results demonstrated increasing of average diameters of nanofibers for the concentration 1and 2% of catalysts in comparison with the pure PU samples. But fibers with 3 and 4% of SnO2/CrO2 particles showed the decreasing of average fiber diameters. The presence of catalyst on the nanofiber`s surface was proved by the method of Energy Dispersive Spectroscopy (EDS). The catalytic properties of produced nanolayers in the reaction with emission's gases were studied with the measurement setup consisting from the engine, a system of analyzers and UV lamp as a sourse of energy to activate the catalyst. All samples demonstrated good catalytic efficiency. The best result showed the sample of PU nanofibers with 3% of SnO2/CrO: the concentrations of CO and NOx reduced by 81% and 73% respectively. Produced samples are the promising materials for air-conditioning systems.
Thomas W. Krause; P. Ross Underhill
Abstract
Eddy current (EC) technology for inspection of conducting materials is a potential solution when conditions preclude the application of other methods. Such conditions include presence of sound absorbing coatings, unavailability of a couplant, multiple conducting layers with air gaps, limited access or ...
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Eddy current (EC) technology for inspection of conducting materials is a potential solution when conditions preclude the application of other methods. Such conditions include presence of sound absorbing coatings, unavailability of a couplant, multiple conducting layers with air gaps, limited access or near surface cladding. However, the choice of a particular EC technology may not be clear due to sources of electromagnetic interference, choice of probe design, target configuration or even available equipment. In addition, the choice of EC based technologies is extensive, including conventional EC, low frequency EC, remote field EC and pulsed EC. Each of these technologies has its own challenges and limitations, which need to be considered prior to a commitment to system development. Probe choice becomes a function of the particular technique that has been selected and may include ferrite core sensing coils, GMRs or eddy current coil array. Finally, EC signal analysis methods need to be selected based on effects of potentially multiple varying parameters. This paper examines the potential of electromagnetic inspection technology, discussing its limitations, effects of common essential parameters and analysis methodologies. Examples of recent technology applications are given and the benefits and limitations of various technologies are compared and discussed.
Yuvaraj Sivalingam; Arnaldo D Amico;Corrado Di Natale; Gabriele Magna; Giuseppe Pomarico; Eugenio Martinelli; Roberto Paolesse
Abstract
Recent studies suggest that the gas sensitivity of porphyrin-functionalized ZnO nanorods can be activated under visible light illumination. Then the use of properly coloured light tuned to the absorbance spectra of individual porphyrins could enable a control of sensors sensitivity. The effect of light ...
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Recent studies suggest that the gas sensitivity of porphyrin-functionalized ZnO nanorods can be activated under visible light illumination. Then the use of properly coloured light tuned to the absorbance spectra of individual porphyrins could enable a control of sensors sensitivity. The effect of light on the sensitivity to gases is critically governed by the transport phenomena of electronic charge across the interfaces of organic and inorganic structures. Therefore, accurate measurements of energy levels and contact potential differences in porphyrins functionalized ZnO nanorods are important to intepret the sensing properties of such hybrid materials. For the scope, Kelvin probe measurements of porphyrin-ZnO structures were performed exposing the material in dark and visible light and to organic vapours. Results provide an experimental basis to understand the mutual effects of gas adsorption and illumination to the device conductivity.
Yossef Danan; Ariel Schwarz; Moshe Sinvani; Zeev Zalevsky
Abstract
In the last decade diversity of applications in the fields of diagnostics and treatment for biomedical applications using gold nanoparticles (GNPs) as contrast agent sprang up. The strong optical absorption and scattering properties of the GNPs due to their localized surface plasmon resonance (LSPR) ...
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In the last decade diversity of applications in the fields of diagnostics and treatment for biomedical applications using gold nanoparticles (GNPs) as contrast agent sprang up. The strong optical absorption and scattering properties of the GNPs due to their localized surface plasmon resonance (LSPR) effect enables their use as contrast agents in these applications. The usage of the light-scattering properties of the GNPs in most imaging methods lead to background noise stems from light scattering from the tissue due to the same wavelengths of the illumination source and the GNPs’ scattering. In our previous works we presented a method to improve border detection of bio-phantoms enriched with GNPs leading for real-time complete tumor resection by using a modulated laser illumination, photo thermal imaging camera and the optical absorption of specially targeted GNPs. In this system the thermal camera detects the temperature field of the illuminated bio-phantoms. Although the surrounding area got heated the border location was detected at a precision of at least 0.5 mm through use of a simple post processing technique. In this paper, we present a continuation of our previous research with modified system of time sequence labelling (TSL) processing for improved border detection capable of operating and detecting borders at much lower signal to noise levels.
Ram Krishna Upadhyay; Lakshmi Annamalai Kumaraswamidhas
Abstract
Tribological study includes surface interaction and mechanism involve between contacts. At contact points, surface forces affect the geometry and properties of material whereas stress concentration affects processes that involve during friction interactions. Nanomechanical behaviour of thin-film and ...
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Tribological study includes surface interaction and mechanism involve between contacts. At contact points, surface forces affect the geometry and properties of material whereas stress concentration affects processes that involve during friction interactions. Nanomechanical behaviour of thin-film and surfaces has been largely studied during past years in the field of electronics industry such as microelectronics, optoelectronics application, aerospace industry, iron and steel industries and also adapted in the field of biological sector that likely to grow in near future extensively. High resolution microscope and computational techniques enable the material to investigate their interfacial problems at nanoscale. In this, we studied mechanism of tribology, with different deposition technique and their mechanical properties.
Sachin B Undre; Shivani R. Pandya; Vinod Kumar; Man Singh
Abstract
Developing new smart materials and tracking their structural potential have been in focus for curing disease and other applications such as catalyzing biomolecules like proteins and selective bioremediation of toxic metals, dyes, pesticides have been thrust areas of research in the field of materials ...
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Developing new smart materials and tracking their structural potential have been in focus for curing disease and other applications such as catalyzing biomolecules like proteins and selective bioremediation of toxic metals, dyes, pesticides have been thrust areas of research in the field of materials and biomaterials sciences. Since materials are most important need of the society which develops somewhere food, drug, fuel, protective cover, defense materials, fire resistant and acoustic mechanism, UV sensitive, UV absorbing, solar radiation trapping activities. In this context, the dendrimers have been considered as ideal and smart materials to be applied for wider applications and directly, indirectly or catalyze modulator and many others. Thus, the dendrimers act as smart materials and the synthesis of such architectural and potential molecules is being considered as a new thrust area for multitasking materials with better activities to catalyze chemical and biochemical processes. The multifunctional materials of multipurpose uses with several dendrimeric branching, having innumerable binding sites and are in high demands for their drug binding, loading potential and bio coatings.
Neha Sharma;Rita Kakkar
Abstract
Chemical warfare agents (CWA) have been used in the World Wars and in terrorist attacks, and hence there is an urgent need to find means of their decontamination. Metal oxides offer a rapid means of their disposal, since they contain reactive Lewis acid and basic sites, on which adsorption of the CWA, ...
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Chemical warfare agents (CWA) have been used in the World Wars and in terrorist attacks, and hence there is an urgent need to find means of their decontamination. Metal oxides offer a rapid means of their disposal, since they contain reactive Lewis acid and basic sites, on which adsorption of the CWA, and subsequent hydrolysis, can take place. Destructive adsorption of CWA on metal oxides yields non-toxic products. Nanoscale metal oxides display enhanced reactive properties toward warfare agents due to their high surface area, large number of highly reactive edges, corner defect sites, unusual lattice planes and high surface to volume ratio. Both experimental and theoretical studies have established that decomposition of nerve agents is facilitated on nanoscale Al2O3, MgO, CaO, TiO2, ZnO and small edge and corner clay mineral fragments. Compared to sulfur mustard, nerve agents are more potent. We first briefly describe their mode of action. Many experimental and theoretical studies have been performed to study their decomposition on various metal oxide surfaces, such as MgO, CaO, Al2O3, TiO2, V2O5, and clay minerals. The results of these studies are reviewed here. Photochemical degradation on TiO2 nanosurfaces has also yielded promising results. Because of the toxicity and risk involved, experimental studies have been mostly confined to the benign simulants, whereas theoretical studies have attempted to compare the real agents with their mimics. These studies establish a qualitative correlation between the G-agents and their simulant DMMP, and, hence, decomposition on metal oxide surfaces can be analyzed by observing the surface chemistry of DMMP on a wide variety of metal oxide surfaces. This review attempts to compile the literature concerning CWA and their simulants.
Naoki Komatsu
Abstract
Nanocarbons are carbon allotropes with nanometer scale and comprised mainly of 0 – 3 dimensional (0D – 3D) forms; fullerenes (0D), carbon nanotubes (1D), graphene (2D), and nanodiamond (3D). In our group, various surfactants with appropriate size and shape have been developed for the nanocarbons. ...
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Nanocarbons are carbon allotropes with nanometer scale and comprised mainly of 0 – 3 dimensional (0D – 3D) forms; fullerenes (0D), carbon nanotubes (1D), graphene (2D), and nanodiamond (3D). In our group, various surfactants with appropriate size and shape have been developed for the nanocarbons. In order to separate the fullerenes, bowl-shaped surfactants were designed and synthesized to accommodate the 0D spherical nanocarbon, giving C70 selectively as precipitates. On the other hand, gable- and bracket-shaped surfactants formed stable complexes with 1D tubular nanocarbons, dispersing carbon nanotubes with specific diameter, handedness and/or metallicity selectively in solution phase. The flat surfactants worked as an exfoliant and dispersant for graphite in both wet and dry processes; sonication and ball milling, respectively. They gave graphene composites with high concentrations and yield in aqueous solution and low-boiling point organic solvents. The hyper-branched polymer named polyglycerol coated the nanodiamond surface covalently through ring-opening polymerization of glycidol. The chemisorped polymer gave large hydrophilicity to the nanodiamond, dispersing it stably in aqueous solutions such as water and phosphate buffer as well as polar organic solvents such as methanol. Copyright © VBRI Press.
Dillip Kumar Biswal; Payodhar Padhi
Abstract
Ionic polymer-metal composites (IPMCs) are electro-active polymers that undergo bending deformation with the stimulus of a relatively small electric field. In this research we fabricate multilayered structure of IPMC actuator using chemical decomposition method and investigate the influence of bending ...
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Ionic polymer-metal composites (IPMCs) are electro-active polymers that undergo bending deformation with the stimulus of a relatively small electric field. In this research we fabricate multilayered structure of IPMC actuator using chemical decomposition method and investigate the influence of bending response on applied input voltage. The experimentally obtained results had been compared to single layered IPMC actuator. The result shows that the increment of layer on base material (Nafion-117) had increased the actuation capability of IPMC actuator. The tip displacement increases up to 20% for three layered and around 30% for four layered compared to single layered IPMC actuator under the application of 1.0V. This finding would be useful for the application where higher bending displacement is required i.e., in the robotic and biomimetic application with a very small input voltage.
Mahesh S. Edake; Shriniwas D. Samant
Abstract
Solvent free and selective isomerization of p-diethylbenzene (p-DEB) to m-diethylbenzene (m-DEB) was carried out using metal modified zeolite Hβ at high temperature. The metal modification of Hβ catalyst was carried out by using typical Lewis acidic cations Al 3+ , Fe 3+ , Ti 4+ , Sn 4+ and ...
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Solvent free and selective isomerization of p-diethylbenzene (p-DEB) to m-diethylbenzene (m-DEB) was carried out using metal modified zeolite Hβ at high temperature. The metal modification of Hβ catalyst was carried out by using typical Lewis acidic cations Al 3+ , Fe 3+ , Ti 4+ , Sn 4+ and Sb 3+ . The catalysts were characterized by XRD, FE-SEM, HR-TEM, FT-IR, N2-desorption (BET), ICP-AES, NH3-TPD, pyridine-IR, and TGA techniques for structure, morphology, acidity and stability. Particle size of the crystallites was determined by HR-TEM and the size was in the range of 15 - 35 nm. At 250oC, Al-Hβ, Fe-Hβ and Ti-Hβ catalysts showed 69 - 75% conversion of p-DEB with 43 - 51% selectivity towards m-DEB. This process is a greener alternative to the classical AlCl3 process. Further, such an isomerization would make the styrene manufacture more economic.
M. A. Jalaja; Soma Dutta
Abstract
Growing energy crisis and environmental issues demand alternative source of green energy. In recent years ferroelectrics and multiferroics have got renewed attention for the breakthrough in photovoltaic application. Multiferroic is an appealing class of material, having two or more ferroic properties ...
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Growing energy crisis and environmental issues demand alternative source of green energy. In recent years ferroelectrics and multiferroics have got renewed attention for the breakthrough in photovoltaic application. Multiferroic is an appealing class of material, having two or more ferroic properties intimately coupled to each other. Energy harvesting from ferroelectrics and multiferroics is a pioneering field of research by its own, combination of other ferroic properties is a value addition to it. The coupling of ferroic and optical properties has brought a revolution in the field of photovoltaics. This review highlights recent development in the field of ferroelectric-multiferroic photovoltaics and summarizes the electrical, optical and photovoltaic properties of various ferroelctric and multiferroic systems. The different mechanisms and factors that attribute to the photovoltaic phenomena in ferroelctrics and multiferroics are also described here.
Anna Maria Coclite
Abstract
Functional organic thin films (< 100 nm) are typical components of current devices in a variety of fields, including microelectronics, biotechnology and microfluidics. The need for miniaturization and structuration has boosted the development of advanced thin film growth techniques that can be easily ...
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Functional organic thin films (< 100 nm) are typical components of current devices in a variety of fields, including microelectronics, biotechnology and microfluidics. The need for miniaturization and structuration has boosted the development of advanced thin film growth techniques that can be easily implemented in the manufacturing steps of current device production. This review aims at presenting the latest progresses made in the field of chemical vapor deposition (CVD) methods of organic thin films. In CVD processes, the chemicals are delivered through the vapor-phase to the substrate, without the use of solvents, with the advantage of enlarging the applicability of polymer thin films to fields where the presence of solvent is detrimental. Among other methods, the initiated Chemical Vapor Deposition (iCVD) will be reviewed. High control over chemical composition, structure and film functionality has been largely demonstrated by iCVD. This technique allows coating virtually any substrate with conformal polymers at very low energy consumption. The specific chemical composition and the nanoengineered thickness control are desirable parameters for driving application-specific properties into the material. Further development of this field will certainly lead to progresses on the use of polymers in functional devices, as electrolytes, stimuli-responsive materials, encapsulants for drug-delivery and as membranes or barriers for permeation.
Jyoti Rozra; Isha Saini; Sanjeev Aggarwal; Annu Sharma
Abstract
Structural and optical properties of Ag-glass nanocomposite, synthesized by the combined use of vacuum deposition method and subsequent thermal annealing have been studied using UV-Visible absorption spectroscopy, Field emission scanning electron microscopy (FE-SEM) along with Energy dispersive analysis ...
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Structural and optical properties of Ag-glass nanocomposite, synthesized by the combined use of vacuum deposition method and subsequent thermal annealing have been studied using UV-Visible absorption spectroscopy, Field emission scanning electron microscopy (FE-SEM) along with Energy dispersive analysis of X-rays (EDAX), Transmission electron microscopy (TEM) and Photoluminescence spectroscopy. Ag-glass nanocomposites were synthesized by depositing Ag on glass slides and the resulting samples were annealed at various temperatures from 300°C to 550°C for 1 hour. The fingerprint feature of Ag nanoparticles formation i.e. the surface plasmon resonance peak is observed around 427 nm in absorption spectra of Ag-glass samples annealed at various temperatures, this confirms the formation of Ag nanoparticles in glass. The size of Ag nanoparticles has been found to increase with increase in annealing temperature. At an annealing temperature of 400°C the size of Ag nanoparticles comes out to be 4.6 nm which increases to a value of 10.0 nm at an annealing temperature of 550°C. TEM micrograph further confirms the formation of Ag nanoparticles of size 8 + 2 nm at an annealing temperature of 550°C. Further, analysis of UV-Visible absorption and reflection data indicates towards the increase in refractive index of Ag nanoparticles doped glasses. It has been established that with the insertion of Ag nanoparticles of size 8 + 2 in glass the refractive index of the resulting nanocomposite increases to a value of 1.96. The dispersion parameters such as single-oscillator energy Eo, and the dispersion energy Ed have been discussed in terms of the Wemple-DiDomenico single-oscillator model. Photoluminescence spectra of silver glass nanocomposite have been studied and observed spectroscopic features have been correlated with various transitions of silver ions. Such studies are vital for designing optical materials for example optical communication, photonic devices etc.
Avishek Das; Ajay Kushwaha; Nakul Raj Bansal; Vignesh Suresh; Sanghamitra Dinda; Sanatan Chattopadhyay; Goutam Kumar Dalapati
Abstract
In the present work, cupric oxide (CuO) nanoparticle (NP) thin films were synthesized on glass by combination of sputter and chemical bath deposition technique. The CuO seeds were deposited by using radio frequency (RF) sputter technique at room temperature. CuO nanoparticles were prepared by chemical ...
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In the present work, cupric oxide (CuO) nanoparticle (NP) thin films were synthesized on glass by combination of sputter and chemical bath deposition technique. The CuO seeds were deposited by using radio frequency (RF) sputter technique at room temperature. CuO nanoparticles were prepared by chemical bath deposition. Effect of solute molar concentration (0.02 to 0.04M) and annealing temperature (at 400°C) on nanoparticles size and distribution were studied. The average size of nanoparticles is small in lower molar concentration, which is restructured after annealing to form dense film with relative smaller size nanoparticles. The work opens up new route to synthesize CuO nanorticle thin films for different applications.
Chao Zheng
Abstract
In this article, we review the recent works of quantum simulation of novel systems briefly, the parity-time-reversal-symmetric (PT-symmetric) quantum system and the Yang-Baxter-equation (YBE) system, using duality quantum algorithm. Duality quantum algorithm studies the linear combinations of unitary ...
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In this article, we review the recent works of quantum simulation of novel systems briefly, the parity-time-reversal-symmetric (PT-symmetric) quantum system and the Yang-Baxter-equation (YBE) system, using duality quantum algorithm. Duality quantum algorithm studies the linear combinations of unitary operators, making it possible to simulate non-unitary evolutions of novel quantum systems. A PT-symmetric quantum system is a typical non-Hermitian system of which the evolution is not unitary and cannot be simulated directly by a conventional quantum computer. A recent work by C. Zheng has established a theory to simulate a general PT-symmetric two level system by duality quantum computing. The other typical example is the YBE quantum systems, of which the evolutions can be both unitary and non-unitary. C. Zheng and S. J. Wei described a theory that the two hand sides of the YBE can be simulated efficiently by the duality quantum algorithm in their recent research. Perspectives of future applications are expected at last. Copyright © VBRI Press.
Pragati Malik; Jyoti Singh; Rita Kakkar
Abstract
The primary aim of this review is to survey the literature on the ion sensing ability of quantum dots. Sensing of both cations and anions is important, since both play significant roles in various ecological and biological processes, which makes it important to ensure their concentration at balanced ...
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The primary aim of this review is to survey the literature on the ion sensing ability of quantum dots. Sensing of both cations and anions is important, since both play significant roles in various ecological and biological processes, which makes it important to ensure their concentration at balanced level. Contamination by heavy metal ions and various anions poses a serious threat to humans, aquatic organisms, and to the environment; therefore detection of these ions (in presence of other cations and anions), which are the major cause of environmental pollution is of immense significance at the present time. Owing to their enhanced fluorescence properties and photostability, QDs offer tremendous scope to be used for ion sensing. They offer several advantages over traditional chemical fluorophores. This review throws light on the mechanism adopted by CdSe QDs to act as flourophores. Owing to their enhanced photoluminescence properties, QDs offer selective and sensitive determination of various ions, which is a function of the capping on the surface of the QD nanosensor, i.e. it is possible to tune their sensing ability by changing the capping layer, which influences the QD's interaction with various analytes. Hence, these quantum dots may prove promising candidates in future for sensing approximately all types of analytes.
Yang Fu; Runze Liu; Jinfang Zhi
Abstract
A novel electrochemical strategy for economical, environmental-friendly, simple and facile synthesis of glycine functionalized graphene quantum dots (GQDs) based on direct exfoliation and oxidation from graphite rods was reported. The average diameter of as-synthesized GQDs is 30 nm. Due to the rich ...
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A novel electrochemical strategy for economical, environmental-friendly, simple and facile synthesis of glycine functionalized graphene quantum dots (GQDs) based on direct exfoliation and oxidation from graphite rods was reported. The average diameter of as-synthesized GQDs is 30 nm. Due to the rich nitrogen and oxygen functional groups on the surface of GQDs, the GQDs dispersion was bright yellow and further applied in selective detection of ferric ion (Fe 3+ ). A sensor based on photoluminescence quenching of GQDs after adding Fe 3+ has a limit of detection of 3.09 μM, which is lower than the maximum level (0.3 mg/L, equivalent to 5.4 µM) of Fe 3+ permitted in drinking water by the U.S. Environmental Protection Agency (EPA). The fluorescent sensor has a wide linear range of 10–150 μM. Moreover, due to the low cytotoxicity of as-prepared GQDs, this study may provide a new analytical platform for further applications of GQDs in real environmental and biological system.
Anupama Chaturvedi; Ashutosh Tiwari; Atul Tiwari
Abstract
This communication describes the development of graphene and graphene reinforced polyvinylester nanocomposites. Low concentration of graphene was incorporated in the polymer matrix with the help of two different solvents. The role of solvent in the nanocomposite was studied. The FTIR spectroscopy and ...
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This communication describes the development of graphene and graphene reinforced polyvinylester nanocomposites. Low concentration of graphene was incorporated in the polymer matrix with the help of two different solvents. The role of solvent in the nanocomposite was studied. The FTIR spectroscopy and electron microscopy have supported the presence of graphene in the nanocomposites. It was discovered that vehicular medium (i.e., solvent) plays a vital role in the properties of the ultimate nanocomposites. When dimethylacetamide was used as solvent, the morphological analysis suggested the increased toughness while in case when tetrahydrofuran was used as solvent, nanocomposite appeared brittle in nature.
S. Som; S. Dutta; Subrata Das; Mukesh Kumar Pandey; Ritesh Kumar Dubey; S. P. Lochab; S. K. Sharma
Abstract
Herein, a comparative study on the structural and luminescence properties of optimized Y2O3:Eu 3+ /Tb 3+ nanophosphor has been reported after 150 MeV Ni 7+ , 120 MeV Ag 9+ and 110 MeV Au 8+ ion beam irradiation at various fluences ranging from 1×10 11 to 1×10 13 ions/cm 2 . The X-ray diffraction ...
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Herein, a comparative study on the structural and luminescence properties of optimized Y2O3:Eu 3+ /Tb 3+ nanophosphor has been reported after 150 MeV Ni 7+ , 120 MeV Ag 9+ and 110 MeV Au 8+ ion beam irradiation at various fluences ranging from 1×10 11 to 1×10 13 ions/cm 2 . The X-ray diffraction results confirm the cubic phase in case of unirradiatedY 2 O 3 :Eu 3+ /Tb 3+ nanophosphor. The loss of crystallinity was observed after ion irradiation and Au ion is more effective to damage the crystal structure in these phosphors. The transmission electron microscopic results show the reduction of the particle size from 100 nm to 50, 30 and 20 nm after ion irradiation with the Ni 7+ , Ag 9+ and Au 8+ ions, respectively. Diffuse reflectance spectra show a blue shift in the absorption band owing to the increase in the band gap after ion irradiation. An increase in the photoluminescence intensity without any shift in the peak positions was observed with the increase in the ion fluence. The colour tunability was observed with ion irradiation as the colour coordinate varies from red to white chromaticity.
Wee Siang Koh; Kiat Moon Lee; Pey Yi Toh; Swee Pin Yeap
Abstract
Along with technology development, the demand for flexible, foldable, and portable electronic devices has grew over the past few years. Successful fabrication of this flexible electronic devices relying on the internal electronic components which are also flexible and lightweight. In this regard, researchers ...
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Along with technology development, the demand for flexible, foldable, and portable electronic devices has grew over the past few years. Successful fabrication of this flexible electronic devices relying on the internal electronic components which are also flexible and lightweight. In this regard, researchers are now working on using nanomaterials which exhibit the desired electronic properties to replace the conventional electronic components. Graphene nanosheet and its derivatives are known for their intrinsic electrical behaviour. Meanwhile, they are lightweight and consume small space in any design. Hence, recent research has been focussing on fabricating flexible and foldable electronic components by attaching the graphene and its derivatives on a thin film/substrate. In fact, this idea has been realized in year 2017 on the first flexible OLED panel that uses transparent graphene-based electrode. In view of the positive impact of this nanomaterial towards future design of electronic devices, the present paper aims to provide a quick review on the current stage of research, the challenges encountered, as well as the future outlook in the use of graphene nanomaterials for designing flexible electronics. Copyright © VBRI Press.
Go Ozeki; A. Toshimitsu Yokobori; Toshihito Ohmi; Tadashi Kasuya; Nobuyuki Ishikawa; Satoshi Minamoto; Manabu Enoki
Abstract
It is important to predict the stress driven hydrogen induced cracking at the weld joint on the basis of computational mechanics from the view point of engineering problem. In this study, On the basis of proposed numerical analysis, behaviors of hydrogen diffusion and concentration during cooling process ...
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It is important to predict the stress driven hydrogen induced cracking at the weld joint on the basis of computational mechanics from the view point of engineering problem. In this study, On the basis of proposed numerical analysis, behaviors of hydrogen diffusion and concentration during cooling process of y-grooved weld joint were analyzed and the mechanism of hydrogen induced cracking was investigated. One of authors has been proposed a multiplication method which magnifies the hydrogen driving term in the diffusion equation to realize correctly hydrogen concentration behaviors. In this study, the behaviors of hydrogen diffusion and concentration for the model of y-grooved weld joint was analyzed by combining a multiplication method with the coupled analyses of heat transfer – thermal stress – hydrogen diffusion. As a result, hydrogen was found to diffuse from weld metal to base metal through HAZ (Heat Affected Zone), and concentrate at the position of blunt angle side of weld groove bottom. It was found that hydrogen concentrates at the position of the local maximum value of hydrostatic stress gradient. This analytical result was found to well predict the actual hydrogen induced cracking of the y-grooved weld joint. Using this method of analysis, prediction of hydrogen induced cracking becomes possible.
Mallory Clites; Bryan W. Byles; Ekaterina Pomerantseva
Abstract
Bilayered vanadium oxide has emerged as a high-performance cathode material for beyond lithium ion (BLI) battery systems including Na-ion batteries, Mg-ion batteries, and pseudocapacitors. The major structural feature of bilayered V2O5 that makes it attractive for such applications is its large interlayer ...
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Bilayered vanadium oxide has emerged as a high-performance cathode material for beyond lithium ion (BLI) battery systems including Na-ion batteries, Mg-ion batteries, and pseudocapacitors. The major structural feature of bilayered V2O5 that makes it attractive for such applications is its large interlayer spacing of ~10-13 Å. This spacing can be controlled via the interlayer content, which can consist of varying amounts of structural water and/or inorganic ions, resulting in numerous chemical compositions. Further, bilayered V2O5 can be synthesized via a number of different methods, resulting in morphologies that include xerogel, aerogel, thin films, and 1-D nanostructures. The interlayer spacing, content, and material morphology can all affect the electrochemical performance of this materials family, and in this review, we discuss the role of each of these factors in the reversible cycling of charge-carrying ions beyond lithium. The different bilayered V2O5 synthesis methods and resulting compositions are reviewed, and important structure-property-performance insights into the reversible insertion/ extraction of larger/multivalent ions into the bilayered V2O5 structure are highlighted.
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