Applied Sciences

746 KiB

Open AccessArticle

Electrical Properties of Graphene for Interconnect Applications

by Antonio Maffucci and Giovanni Miano

Appl. Sci. 2014, 4(2), 305-317; https://doi.org/10.3390/app4020305 - 30 May 2014

Cited by 32 | Viewed by 16417

A semi-classical electrodynamical model is derived to describe the electrical transport along graphene, based on the modified Boltzmann transport equation. The model is derived in the typical operating conditions predicted for future integrated circuits nano-interconnects, i.e., a low bias condition and an [...] Read more.

A semi-classical electrodynamical model is derived to describe the electrical transport along graphene, based on the modified Boltzmann transport equation. The model is derived in the typical operating conditions predicted for future integrated circuits nano-interconnects, i.e., a low bias condition and an operating frequency up to 1 THz. A generalized non-local dispersive Ohm’s law is derived, which can be regarded as the constitutive equation for the material. The behavior of the electrical conductivity is studied with reference to a 2D case (the infinite graphene layer) and a 1D case (the graphene nanoribbons). The modulation effects of the nanoribbons’ size and chirality are highlighted, as well as the spatial dispersion introduced in the 2D case by the dyadic nature of the conductivity. Full article

(This article belongs to the Special Issue Towards Applications of Graphene)

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622 KiB

Open AccessArticle

Elastic Properties and Stability of Physisorbed Graphene

by Philippe Lambin

Appl. Sci. 2014, 4(2), 282-304; https://doi.org/10.3390/app4020282 - 16 May 2014

Cited by 51 | Viewed by 9335

Abstract

Graphene is an ultimate membrane that mixes both flexibility and mechanical strength, together with many other remarkable properties. A good knowledge of the elastic properties of graphene is prerequisite to any practical application of it in nanoscopic devices. Although this two-dimensional material is [...] Read more.

Graphene is an ultimate membrane that mixes both flexibility and mechanical strength, together with many other remarkable properties. A good knowledge of the elastic properties of graphene is prerequisite to any practical application of it in nanoscopic devices. Although this two-dimensional material is only one atom thick, continuous-medium elasticity can be applied as long as the deformations vary slowly on the atomic scale and provided suitable parameters are used. The present paper aims to be a critical review on this topic that does not assume a specific pre-knowledge of graphene physics. The basis for the paper is the classical Kirchhoff-Love plate theory. It demands a few parameters that can be addressed from many points of view and fitted to independent experimental data. The parameters can also be estimated by electronic structure calculations. Although coming from diverse backgrounds, most of the available data provide a rather coherent picture that gives a good degree of confidence in the classical description of graphene elasticity. The theory can than be used to estimate, e.g., the buckling limit of graphene bound to a substrate. It can also predict the size above which a scrolled graphene sheet will never spontaneously unroll in free space. Full article

(This article belongs to the Special Issue Towards Applications of Graphene)

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4706 KiB

Open AccessArticle

CERN-MEDICIS (Medical Isotopes Collected from ISOLDE): A New Facility

by Ricardo Manuel Dos Santos Augusto, Leo Buehler, Zoe Lawson, Stefano Marzari, Monika Stachura, Thierry Stora and CERN-MEDICIS collaboration

Appl. Sci. 2014, 4(2), 265-281; https://doi.org/10.3390/app4020265 - 16 May 2014

Cited by 73 | Viewed by 13517

Abstract

About 50% of the 1.4 GeV CERN (European Organization for Nuclear Research, www.cern.ch) protons are sent onto targets to produce radioactive beams by online mass separation at the Isotope Separator Online Device (ISOLDE) facility, for a wide range of studies in fundamental and [...] Read more.

About 50% of the 1.4 GeV CERN (European Organization for Nuclear Research, www.cern.ch) protons are sent onto targets to produce radioactive beams by online mass separation at the Isotope Separator Online Device (ISOLDE) facility, for a wide range of studies in fundamental and applied physics. CERN-MEDICIS is a spin-off dedicated to R&D in life sciences and medical applications. It is located in an extension of the Class A building presently under construction. It will comprise laboratories to receive the irradiated targets from a new station located at the dump position behind the ISOLDE production targets. An increasing range of innovative isotopes will thus progressively become accessible from the start-up of the facility in 2015 onward; for fundamental studies in cancer research, for new imaging and therapy protocols in cell and animal models and for pre-clinical trials, possibly extended to specific early phase clinical studies up to Phase I trials. Five hundred megabecquerel isotope batches purified by electromagnetic mass separation combined with chemical methods will be collected on a weekly basis. A possible future upgrade with gigabecquerel pharmaceutical-grade i.e., current good manufacturing practices (cGMP) batch production capabilities is finally presented. Full article

(This article belongs to the Special Issue Radioisotope Production and Applications)

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2537 KiB

Open AccessArticle

Electromagnetic Properties of Graphene-like Films in K_a-Band

by Sofia Voronovich, Alesya Paddubskaya, Konstantin Batrakov, Polina Kuzhir, Sergey Maksimenko, Tommi Kaplas and Yuri Svirko

Appl. Sci. 2014, 4(2), 255-264; https://doi.org/10.3390/app4020255 - 15 May 2014

Cited by 8 | Viewed by 6020

Abstract

We studied electromagnetic properties of pyrolytic carbon (PyC) films with thicknesses from 9 nm to 110 nm. The PyC films consisted of randomly oriented and intertwined graphene flakes with a typical size of a few nanometers were synthesized by chemical vapor deposition (CVD) [...] Read more.

We studied electromagnetic properties of pyrolytic carbon (PyC) films with thicknesses from 9 nm to 110 nm. The PyC films consisted of randomly oriented and intertwined graphene flakes with a typical size of a few nanometers were synthesized by chemical vapor deposition (CVD) at 1100 °C on a quartz substrate. The reflectance and transmittance of these films in K_a-band, 26–37 GHz, were studied both experimentally and theoretically. The discovered remarkably high absorption loss of up to 50% of incident power, along with chemical stability, makes PyC films attractive for electromagnetic (EM) interference shielding in space and airspace communication systems, as well as in portable electronic devices occupying this frequency slot. Since, in practical applications, the PyC film should be employed for coating of dielectric surfaces, two important issues to be addressed are: (i) which side (front or back) of the substrate should be covered to ensure maximum absorption losses; and (ii) the frequency dependence of absorbance/transmittance/reflectance of binary PyC/quartz structures in the K_a-band. Full article

(This article belongs to the Special Issue Towards Applications of Graphene)

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4485 KiB

Open AccessArticle

Mobilization of Toxic Elements from an Abandoned Manganese Mine in the Arid Metropolitan Las Vegas (NV, USA) Area

by Ji Hye Park, Vernon Hodge, Shawn Gerstenberger and Krystyna Stave

Appl. Sci. 2014, 4(2), 240-254; https://doi.org/10.3390/app4020240 - 12 May 2014

Cited by 7 | Viewed by 8163

Abstract

Active and abandoned mines may present health risks, especially to children, from environmental exposure to airborne chemical elements, such as Pb, As, and Mn. X-ray fluorescence analysis of tailings at the Three Kids Mine show they contain high levels of: Pb (15,300 mg/kg), [...] Read more.

Active and abandoned mines may present health risks, especially to children, from environmental exposure to airborne chemical elements, such as Pb, As, and Mn. X-ray fluorescence analysis of tailings at the Three Kids Mine show they contain high levels of: Pb (15,300 mg/kg), As (3690 mg/kg), and Mn (153,000 mg/kg). Soil was sampled along eight transects, radiating from the dried tailings ponds. Concentrations of Mn and Pb to the NE are at background concentrations at 4.8 km, and, As and Sr at 3.2 km from the mine. Going SW to the City of Henderson, all elements are at background at 1.6 cm, with the closest houses at 1.8 km. The United States Environmental Protection Agency (USEPA) Regional Screening Levels (RSLs) are exceeded for Pb, As and Mn at 0.8 km on all transects except one. The RSLs are exceeded for Pb, As and Mn on the NE transects at 1.6 km. Future home sites are on a NE transect between 0.4 km and 2.3 km downwind from the tailings ponds, in an area highly impacted by tailings which exceed the USEPA RSLs. This research demonstrates that there has been the farthest transport of tailings offsite by the prevailing winds to the NE; the closest currently-built homes have not received measurable tailings dust because they are upwind; and that precautions must be taken during the proposed remediation of the mine to restrict dust-transport of Pb, As, and Mn to avoid human exposure and ecological damage. Full article

(This article belongs to the Special Issue Environmental Pollution Research and Monitoring)

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3711 KiB

Open AccessReview

Intra- and Interlayer Electron-Phonon Interactions in ^12/12C and ^12/13C BiLayer Graphene

by Daniela L. Mafra and Paulo T. Araujo

Appl. Sci. 2014, 4(2), 207-239; https://doi.org/10.3390/app4020207 - 29 Apr 2014

Cited by 8 | Viewed by 8806

Abstract

This review focuses on intra- and interlayer (IL) electron-phonon interactions and phonon self-energy renormalizations in twisted and AB-stacked bilayer graphene (2LG) composed either only of 12C or a mixing of 12C and 13C isotopes. A simple way to imagine a 2LG is by [...] Read more.

This review focuses on intra- and interlayer (IL) electron-phonon interactions and phonon self-energy renormalizations in twisted and AB-stacked bilayer graphene (2LG) composed either only of 12C or a mixing of 12C and 13C isotopes. A simple way to imagine a 2LG is by placing one monolayer graphene (1LG) on top of another 1LG. The orientation of one of the layers with relation to the other may originate a twisted 2LG system (known as turbostratic) as well as a AB-stacked system, also known as Bernal stacking. By rotating the layers of a 2LG one can departure from a fully misoriented system to achieve the AB-stacked configuration and their IL interactions can be dramatically different being close to zero in a fully misoriented system and maximum in an AB-stacked system. Interlayer interactions are expected to slightly perturb the intralayer phonons and they also govern the low-energy electronic and vibrational properties, which are of primary importance to phenomena such as transport, infrared (IR) optics and telecommunication bands in the IR range. Therefore, a comprehensive discussion combining intra- and interlayer phenomena is necessary and addressed throughout the text. Full article

(This article belongs to the Special Issue Towards Applications of Graphene)

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1809 KiB

Open AccessArticle

Chemical Surface, Thermal and Electrical Characterization of Nafion Membranes Doped with IL-Cations

by María Del Valle Martínez de Yuso, Ana Arango-Díaz, Shanti Bijani, Virgina Romero, Juana Benavente and Enrique Rodríguez-Castellón

Appl. Sci. 2014, 4(2), 195-206; https://doi.org/10.3390/app4020195 - 29 Apr 2014

Cited by 9 | Viewed by 6880

Abstract

Surface and bulk changes in a Nafion membrane as a result of IL-cation doping (1-butyl-3-methylimidazolium tetrafluoroborate or BMIM⁺BF₄ and phenyltrimethylammonium chloride or TMPA⁺Cl⁻) were studied by X-ray photoelectron spectroscopy (XPS), contact angle, differential scanning calorimetry (DSC) [...] Read more.

Surface and bulk changes in a Nafion membrane as a result of IL-cation doping (1-butyl-3-methylimidazolium tetrafluoroborate or BMIM⁺BF₄ and phenyltrimethylammonium chloride or TMPA⁺Cl⁻) were studied by X-ray photoelectron spectroscopy (XPS), contact angle, differential scanning calorimetry (DSC) and impedance spectroscopy (IS) measurements performed with dry samples after 24 h in contact with the IL-cations BMIM⁺ and TMPA⁺. IL-cations were selected due to their similar molecular weight and molar volume but different shape, which could facilitate/obstruct the cation incorporation in the Nafion membrane structure by proton/cation exchange mechanism. The surface coverage of the Nafion membrane by the IL-cations was confirmed by XPS analysis and contact angle, while the results obtained by the other two techniques (DSC and IS) seem to indicate differences in thermal and electrical behaviour depending on the doping-cation, being less resistive the Nafion/BMIM⁺ membrane. For that reason, determination of the ion transport number was obtained for this membrane by measuring the membrane or concentration potential with the samples in contact with HCl solutions at different concentrations. The comparison of these results with those obtained for the original Nafion membrane provides information on the effect of IL-cation BMIM⁺ on the transport of H⁺ across wet Nafion/BMIM⁺ doped membranes. Full article

(This article belongs to the Special Issue Polymer Electrolyte Membrane (PEM) Fuel Cells)

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4674 KiB

Open AccessArticle

Mechanism of Thin Layers Graphite Formation by ¹³C Implantation and Annealing

by Gaelle Gutierrez, François Le Normand, Fitsum Aweke, Dominique Muller, Claude Speisser and Frédéric Antoni

Appl. Sci. 2014, 4(2), 180-194; https://doi.org/10.3390/app4020180 - 21 Apr 2014

Cited by 8 | Viewed by 5631

Abstract

The mechanism of thin layers graphite (TLG) synthesis on a polycrystalline nickel film deposited on SiO₂(300 nm thick)/Si(100) has been investigated by ¹³C implantation of four equivalent graphene monolayers and annealing at moderate temperatures (450–600 °C). During this process, the [...] Read more.

The mechanism of thin layers graphite (TLG) synthesis on a polycrystalline nickel film deposited on SiO₂(300 nm thick)/Si(100) has been investigated by ¹³C implantation of four equivalent graphene monolayers and annealing at moderate temperatures (450–600 °C). During this process, the implanted ¹³C segregates to the surface. Nuclear Reaction Analyses (NRA) are used for the first time in the topic of graphene synthesis to separate the isotopes and to determine the ¹²C and ¹³C concentrations at each step. Indeed, a significant part of carbon in the TLG also comes from residual ¹²C carbon absorbed into the metallic matrix. Raman spectroscopy and imaging are used to determine the main location of each carbon isotope in the TLG. The Raman mappings especially emphasize the role of ¹²C previously present at the surface that first diffuses along grain boundaries. They play the role of nucleation precursors. Around them the implanted ¹³C or a mixture of bulk ¹²C–¹³C aggregate and further precipitate into graphene-like fragments. Graphenization is effective at around 600 °C. These results point out the importance of controlling carbon incorporation, as well as the importance of preparing a uniform nickel surface, in order to avoid heterogeneous nucleation. Full article

(This article belongs to the Special Issue Towards Applications of Graphene)

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245 KiB

Open AccessArticle

A Solvent-Free, One-Step, One-Pot Gewald Reaction for Alkyl-aryl Ketones via Mechanochemistry

by William C. Shearouse, Maxwell Z. Shumba and James Mack

Appl. Sci. 2014, 4(2), 171-179; https://doi.org/10.3390/app4020171 - 08 Apr 2014

Cited by 23 | Viewed by 10064

Abstract

Herein, we report on the solvent-free synthesis of 2-aminothiophenes via the Gewald reaction. Utilizing high speed ball milling conditions, we discovered the Gewald reaction can be catalytic in base, and conducted under aerobic conditions. Using thermal heat in tandem with the mixer/mill significantly [...] Read more.

Herein, we report on the solvent-free synthesis of 2-aminothiophenes via the Gewald reaction. Utilizing high speed ball milling conditions, we discovered the Gewald reaction can be catalytic in base, and conducted under aerobic conditions. Using thermal heat in tandem with the mixer/mill significantly increases the rate of reaction. Full article

(This article belongs to the Special Issue Greener and Sustainable Chemistry)

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578 KiB

Open AccessArticle

Shift Multiplex Recording of Four-Valued Phase Data Pages by Volume Retardagraphy

by Daisuke Barada, Hiroki Sekiguchi, Takashi Fukuda, Shigeo Kawata and Toyohiko Yatagai

Appl. Sci. 2014, 4(2), 158-170; https://doi.org/10.3390/app4020158 - 08 Apr 2014

Cited by 1 | Viewed by 5165

Abstract

In this paper, shift multiplex recording of phase data pages on a volume polarization-sensitive medium by retardagraphy is demonstrated. The origin of shift selectivity in volume retardagraphy is explained. In the experiment, four-valued phase data pages are used. Then, a coding method is [...] Read more.

In this paper, shift multiplex recording of phase data pages on a volume polarization-sensitive medium by retardagraphy is demonstrated. The origin of shift selectivity in volume retardagraphy is explained. In the experiment, four-valued phase data pages are used. Then, a coding method is proposed to correct a reconstructed phase pattern. The recorded phase data pages are reconstructed using the feature of the coding method. By comparing the reconstructed phase data pages with recording phase data pages, symbol error rates of less than 11% are achieved. From the experimental result, it is verified that volume retardagraphy is applicable to optical memory. Full article

(This article belongs to the Special Issue Optical Memory)

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1693 KiB

Open AccessArticle

Shift-Peristrophic Multiplexing for High Density Holographic Data Storage

by Zenta Ushiyama, Hiroyuki Kurata, Yu Tsukamoto, Shuhei Yoshida and Manabu Yamamoto

Appl. Sci. 2014, 4(2), 148-157; https://doi.org/10.3390/app4020148 - 31 Mar 2014

Cited by 16 | Viewed by 6266

Abstract

Holographic data storage is a promising technology that provides very large data storage capacity, and the multiplexing method plays a significant role in increasing this capacity. Various multiplexing methods have been previously researched. In the present study, we propose a shift-peristrophic multiplexing technique [...] Read more.

Holographic data storage is a promising technology that provides very large data storage capacity, and the multiplexing method plays a significant role in increasing this capacity. Various multiplexing methods have been previously researched. In the present study, we propose a shift-peristrophic multiplexing technique that uses spherical reference waves, and experimentally verify that this method efficiently increases the data capacity. In the proposed method, a series of holograms is recorded with shift multiplexing, in which the recording material is rotated with its axis perpendicular to the material’s surface. By iterating this procedure, multiplicity is shown to improve. This method achieves more than 1 Tbits/inch2 data density recording. Furthermore, a capacity increase of several TB per disk is expected by maximizing the recording medium performance. Full article

(This article belongs to the Special Issue Optical Memory)

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3448 KiB

Open AccessArticle

Compressed Sensing-Based Distributed Image Compression

by Muhammad Yousuf Baig, Edmund M-K Lai and Amal Punchihewa

Appl. Sci. 2014, 4(2), 128-147; https://doi.org/10.3390/app4020128 - 31 Mar 2014

Cited by 12 | Viewed by 6297

Abstract

In this paper, a new distributed block-based image compression method based on the principles of compressed sensing (CS) is introduced. The coding and decoding processes are performed entirely in the CS measurement domain. Image blocks are classified into key and non-key blocks and [...] Read more.

In this paper, a new distributed block-based image compression method based on the principles of compressed sensing (CS) is introduced. The coding and decoding processes are performed entirely in the CS measurement domain. Image blocks are classified into key and non-key blocks and encoded at different rates. The encoder makes use of a new adaptive block classification scheme that is based on the mean square error of the CS measurements between blocks. At the decoder, a simple, but effective, side information generation method is used for the decoding of the non-key blocks. Experimental results show that our coding scheme achieves better results than existing CS-based image coding methods. Full article

(This article belongs to the Special Issue Digital Signal Processing and Engineering Applications)

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1134 KiB

Open AccessArticle

Round-Off Noise of Multiplicative FIR Filters Implemented on an FPGA Platform

by Jean-Jacques Vandenbussche, Peter Lee and Joan Peuteman

Appl. Sci. 2014, 4(2), 99-127; https://doi.org/10.3390/app4020099 - 25 Mar 2014

Cited by 3 | Viewed by 5718

Abstract

The paper analyzes the effects of round-off noise on Multiplicative Finite Impulse Response (MFIR) filters used to approximate the behavior of pole filters. General expressions to calculate the signal to round-off noise ratio of a cascade structure of Finite Impulse Response (FIR) filters [...] Read more.

The paper analyzes the effects of round-off noise on Multiplicative Finite Impulse Response (MFIR) filters used to approximate the behavior of pole filters. General expressions to calculate the signal to round-off noise ratio of a cascade structure of Finite Impulse Response (FIR) filters are obtained and applied on the special case of MFIR filters. The analysis is based on fixed-point implementations, which are most common in digital signal processing algorithms implemented in Field-Programmable Gate-Array (FPGA) technology. Three well known scaling methods, i.e., L₂ bound; infinity bound and absolute bound scaling are considered and compared. The paper shows that the ordering of the MFIR stages, in combination with the scaling methods, have an important impact on the round-off noise. An optimal ordering of the stages for a chosen scaling method can improve the round-off noise performance by 20 dB. Full article

(This article belongs to the Special Issue Digital Signal Processing and Engineering Applications)

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Appl. Sci., Volume 4, Issue 2 (June 2014) – 13 articles , Pages 99-317

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