Materials

633 KiB

Open AccessArticle

Cell-Based Fabrication of Organic/Inorganic Composite Gel Material

by Takuya Matsumoto, Ami Mizuno, Miki Kashiwagi, Shin-suke Yoshida, Jun-ichi Sasaki and Takayoshi Nakano

Materials 2011, 4(1), 327-338; https://doi.org/10.3390/ma4010327 - 24 Jan 2011

Cited by 7 | Viewed by 8736

Abstract

Biomaterials containing components similar to the native biological tissue would have benefits as an implantable scaffold material. To obtain such biomimetic materials, cells may be great contributors because of their crucial roles in synthetic organics. In addition, the synthesized organics—especially those derived from [...] Read more.

Biomaterials containing components similar to the native biological tissue would have benefits as an implantable scaffold material. To obtain such biomimetic materials, cells may be great contributors because of their crucial roles in synthetic organics. In addition, the synthesized organics—especially those derived from osteogenic differentiated cells—become a place where mineral crystals nucleate and grow even in vitro. Therefore to fabricate an organic/inorganic composite material, which is similar to the biological osteoid tissue, bone marrow derived mesenchymal stem cells (BMSCs) were cultured in a 3D fibrin gel in this study. BMSCs secreted bone-related proteins that enhanced the biomineralization within the gel when the cells were cultured with an osteogenic differentiation medium. The compositions of both synthesized matrices and precipitated minerals in the obtained materials altered depending on the cell culture period. The mineral obtained in the 3D gel showed low crystalline hydroxyapatite. The composite materials also showed excellent osteoconductivity with new bone formation when implanted in mice tibiae. Thus, we demonstrated the contributions of cells for fabricating implantable organic/inorganic composite gel materials and a method for controlling the material composition in the gel. This cell-based material fabrication method would be a novel method to fabricate organic/inorganic composite biomimetic materials for bone tissue engineering. Full article

(This article belongs to the Special Issue Advances in Biomaterials 2011)

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1779 KiB

Open AccessArticle

Masonry Columns Confined by Steel Fiber Composite Wraps

by Antonio Borri, Giulio Castori and Marco Corradi

Materials 2011, 4(1), 311-326; https://doi.org/10.3390/ma4010311 - 21 Jan 2011

Cited by 44 | Viewed by 10582

Abstract

The application of steel fiber reinforced polymer (SRP) as a means of increasing the capacity of masonry columns is investigated in this study. The behavior of 23 solid-brick specimens that are externally wrapped by SRP sheets in low volumetric ratios is presented. The [...] Read more.

The application of steel fiber reinforced polymer (SRP) as a means of increasing the capacity of masonry columns is investigated in this study. The behavior of 23 solid-brick specimens that are externally wrapped by SRP sheets in low volumetric ratios is presented. The specimens are subjected to axial monotonic load until failure occurs. Two widely used types of masonry columns of differing square cross-sections were tested in compression (square and octagonal cross-sections). It is concluded that SRP-confined masonry behaves very much like fiber reinforced polymers (FRP)-confined masonry. Confinement increases both the load-carrying capacity and the deformability of masonry almost linearly with average confining stress. A comparative analysis between experimental and theoretical values computed in compliance with the Italian Council of Research (CNR) was also developed. Full article

(This article belongs to the Special Issue Innovative Materials in Civil Constructions)

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441 KiB

Open AccessCommunication

{Fe₆O₂}-Based Assembly of a Tetradecanuclear Iron Nanocluster

by Svetlana G. Baca, Manfred Speldrich, Arkady Ellern and Paul Kögerler

Materials 2011, 4(1), 300-310; https://doi.org/10.3390/ma4010300 - 19 Jan 2011

Cited by 13 | Viewed by 7984

Abstract

The tetradecanuclear Fe^III pivalate nanocluster [Fe₁₄O₁₀(OH)₄(Piv)₁₈], comprising a new type of metal oxide framework, has been solvothermally synthesized from a hexanuclear iron pivalate precursor in dichlormethane/acetonitrile solution. Magnetic measurements indicate the presence of very strong antiferromagnetic interactions in the cluster core. Full article

(This article belongs to the Special Issue Molecular Magnets)

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568 KiB

Open AccessCommunication

Laser Fabrication of 3D Gelatin Scaffolds for the Generation of Bioartificial Tissues

by Aleksandr Ovsianikov, Andrea Deiwick, Sandra Van Vlierberghe, Michael Pflaum, Mathias Wilhelmi, Peter Dubruel and Boris Chichkov

Materials 2011, 4(1), 288-299; https://doi.org/10.3390/ma4010288 - 19 Jan 2011

Cited by 125 | Viewed by 13695

Abstract

In the present work, the two-photon polymerization (2PP) technique was applied to develop precisely defined biodegradable 3D tissue engineering scaffolds. The scaffolds were fabricated via photopolymerization of gelatin modified with methacrylamide moieties. The results indicate that the gelatin derivative (GelMod) preserves its enzymatic [...] Read more.

In the present work, the two-photon polymerization (2PP) technique was applied to develop precisely defined biodegradable 3D tissue engineering scaffolds. The scaffolds were fabricated via photopolymerization of gelatin modified with methacrylamide moieties. The results indicate that the gelatin derivative (GelMod) preserves its enzymatic degradation capability after photopolymerization. In addition, the developed scaffolds using 2PP support primary adipose-derived stem cell (ASC) adhesion, proliferation and differentiation into the anticipated lineage. Full article

(This article belongs to the Special Issue Tissue Engineering Scaffolds)

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992 KiB

Open AccessArticle

Enhanced Hydrogen Storage Kinetics of Nanocrystalline and Amorphous Mg₂Ni-type Alloy by Melt Spinning

by Yang-Huan Zhang, Bao-Wei Li, Hui-Ping Ren, Xia Li, Yan Qi and Dong-Liang Zhao

Materials 2011, 4(1), 274-287; https://doi.org/10.3390/ma4010274 - 18 Jan 2011

Cited by 25 | Viewed by 10044

Abstract

Mg₂Ni-type Mg₂Ni_1−xCo_x(x = 0, 0.1, 0.2, 0.3, 0.4) alloys were fabricated by melt spinning technique. The structures of the as-spun alloys were characterized by X-ray diffraction (XRD) and transmission electron microscopy (TEM). The hydrogen absorption [...] Read more.

Mg₂Ni-type Mg₂Ni_1−xCo_x(x = 0, 0.1, 0.2, 0.3, 0.4) alloys were fabricated by melt spinning technique. The structures of the as-spun alloys were characterized by X-ray diffraction (XRD) and transmission electron microscopy (TEM). The hydrogen absorption and desorption kinetics of the alloys were measured by an automatically controlled Sieverts apparatus. The electrochemical hydrogen storage kinetics of the as-spun alloys was tested by an automatic galvanostatic system. The results show that the as-spun (x = 0.1) alloy exhibits a typical nanocrystalline structure, while the as-spun (x = 0.4) alloy displays a nanocrystalline and amorphous structure, confirming that the substitution of Co for Ni notably intensifies the glass forming ability of the Mg₂Ni-type alloy. The melt spinning treatment notably improves the hydriding and dehydriding kinetics as well as the high rate discharge ability (HRD) of the alloys. With an increase in the spinning rate from 0 (as-cast is defined as spinning rate of 0 m/s) to 30 m/s, the hydrogen absorption saturation ratio () of the (x = 0.4) alloy increases from 77.1 to 93.5%, the hydrogen desorption ratio () from 54.5 to 70.2%, the hydrogen diffusion coefficient (D) from 0.75 × 10⁻¹¹ to 3.88 × 10⁻¹¹ cm²/s and the limiting current density I_L from 150.9 to 887.4 mA/g. Full article

(This article belongs to the Special Issue Recent Advances in Hydrogen Storage Materials)

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2722 KiB

Open AccessReview

Electronic and Structural Properties of ABO3: Role of the B-O Coulomb Repulsions for Ferroelectricity

by Kaoru Miura, Masaki Azuma and Hiroshi Funakubo

Materials 2011, 4(1), 260-273; https://doi.org/10.3390/ma4010260 - 17 Jan 2011

Cited by 23 | Viewed by 9081

Abstract

We have investigated the role of the Ti–O Coulomb repulsions in the appearance of the ferroelectric state in BaTiO3 as well as the role of the Zn–O Coulomb repulsions in BiZn0.5Ti0.5O3, using a first-principles calculation with optimized structures. In tetragonal BaTiO3, it is [...] Read more.

We have investigated the role of the Ti–O Coulomb repulsions in the appearance of the ferroelectric state in BaTiO3 as well as the role of the Zn–O Coulomb repulsions in BiZn0.5Ti0.5O3, using a first-principles calculation with optimized structures. In tetragonal BaTiO3, it is found that the Coulomb repulsions between Ti 3s and 3p states and O 2s and 2p states have an important role for the appearance of Ti ion displacement. In BiZn0.5Ti0.5O3, on the other hand, the stronger Zn–O Coulomb repulsions, which are due to the 3s, 3p, and 3d (d10) states of the Zn ion, have more important role than the Ti–O Coulomb repulsions for the appearance of the tetragonal structure. Our suggestion is consistent with the other ferroelectric perovskite oxides ABO3 in the appearance of tetragonal structures as well as rhombohedral structures. Full article

(This article belongs to the Special Issue Advances in Ferroelectric & Piezoelectric Materials)

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1879 KiB

Open AccessReview

Thermotropic Ionic Liquid Crystals

by Kirill V. Axenov and Sabine Laschat

Materials 2011, 4(1), 206-259; https://doi.org/10.3390/ma4010206 - 14 Jan 2011

Cited by 287 | Viewed by 19902

Abstract

The last five years’ achievements in the synthesis and investigation of thermotropic ionic liquid crystals are reviewed. The present review describes the mesomorphic properties displayed by organic, as well as metal-containing ionic mesogens. In addition, a short overview on the ionic polymer and [...] Read more.

The last five years’ achievements in the synthesis and investigation of thermotropic ionic liquid crystals are reviewed. The present review describes the mesomorphic properties displayed by organic, as well as metal-containing ionic mesogens. In addition, a short overview on the ionic polymer and self-assembled liquid crystals is given. Potential and actual applications of ionic mesogens are also discussed. Full article

(This article belongs to the Special Issue Ionic Liquid Crystals)

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1794 KiB

Open AccessReview

Organic Zeolite Analogues Based on Multi-Component Liquid Crystals: Recognition and Transformation of Molecules within Constrained Environments

by Yasuhiro Ishida

Materials 2011, 4(1), 183-205; https://doi.org/10.3390/ma4010183 - 11 Jan 2011

Cited by 20 | Viewed by 8981

Abstract

In liquid crystals (LCs), molecules are confined in peculiar environments, where ordered alignment and certain mobility are realized at the same time. Considering these characteristics, the idea of “controlling molecular events within LC media” seems reasonable. As a suitable system for investigating this [...] Read more.

In liquid crystals (LCs), molecules are confined in peculiar environments, where ordered alignment and certain mobility are realized at the same time. Considering these characteristics, the idea of “controlling molecular events within LC media” seems reasonable. As a suitable system for investigating this challenge, we have recently developed a new class of ionic LCs; the salts of amphiphilic carboxylic acids with 2-amino alcohols, or those of carboxylic acids with amphiphilic 2-amino alcohols, have a strong tendency to exhibit thermotropic LC phases. Because of the noncovalent nature of the interaction between molecules, one of the two components can easily be exchanged with, or transformed into, another molecule, without distorting the original LC architecture. In addition, both components are common organic molecules, and a variety of compounds are easily available. Taking advantage of these characteristics, we have succeeded in applying two‑component LCs as chiral media for molecular recognition and reactions. This review presents an overview of our recent studies, together with notable reports related to this field. Full article

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664 KiB

Open AccessArticle

Roll-to-Roll Processing of Inverted Polymer Solar Cells using Hydrated Vanadium(V)Oxide as a PEDOT:PSS Replacement

by Nieves Espinosa, Henrik Friis Dam, David M. Tanenbaum, Jens W. Andreasen, Mikkel Jørgensen and Frederik C. Krebs

Materials 2011, 4(1), 169-182; https://doi.org/10.3390/ma4010169 - 11 Jan 2011

Cited by 67 | Viewed by 15724

Abstract

The use of hydrated vanadium(V)oxide as a replacement of the commonly employed hole transporting material PEDOT:PSS was explored in this work. Polymer solar cells were prepared by spin coating on glass. Polymer solar cells and modules comprising 16 serially connected cells were prepared [...] Read more.

The use of hydrated vanadium(V)oxide as a replacement of the commonly employed hole transporting material PEDOT:PSS was explored in this work. Polymer solar cells were prepared by spin coating on glass. Polymer solar cells and modules comprising 16 serially connected cells were prepared using full roll-to-roll (R2R) processing of all layers. The devices were prepared on flexible polyethyleneterphthalate (PET) and had the structure PET/ITO/ZnO/P3HT:PCBM/V₂O₅·(H₂O)_n/Ag. The ITO and silver electrodes were processed and patterned by use of screen printing. The zinc oxide, P3HT:PCBM and vanadium(V)oxide layers were processed by slot-die coating. The hydrated vanadium(V)oxide layer was slot-die coated using an isopropanol solution of vanadyl-triisopropoxide (VTIP). Coating experiments were carried out to establish the critical thickness of the hydrated vanadium(V)oxide layer by varying the concentration of the VTIP precursor over two orders of magnitude. Hydrated vanadium(V)oxide layers were characterized by profilometry, scanning electron microscopy, energy dispersive X-ray spectroscopy, and grazing incidence wide angle X-ray scattering. The power conversion efficiency (PCE) for completed modules was up to 0.18%, in contrast to single cells where efficiencies of 0.4% were achieved. Stability tests under indoor and outdoor conditions were accomplished over three weeks on a solar tracker. Full article

(This article belongs to the Special Issue Photovoltaic Materials)

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475 KiB

Open AccessReview

Multiferroic Compounds with Double-Perovskite Structures

by Yuichi Shimakawa, Masaki Azuma and Noriya Ichikawa

Materials 2011, 4(1), 153-168; https://doi.org/10.3390/ma4010153 - 7 Jan 2011

Cited by 119 | Viewed by 14844

Abstract

New multiferroic compounds with double-perovskite structures were synthesized. Bi₂NiMnO₆ was synthesized in bulk form by high-pressure synthesis and also in a thin-film form by epitaxial growth. The material showed both ferromagnetic and ferroelectric properties, i.e., the multiferroic property at [...] Read more.

New multiferroic compounds with double-perovskite structures were synthesized. Bi₂NiMnO₆ was synthesized in bulk form by high-pressure synthesis and also in a thin-film form by epitaxial growth. The material showed both ferromagnetic and ferroelectric properties, i.e., the multiferroic property at low temperature. Bi₂FeCrO₆ was also fabricated in a (1 1 1) oriented BiFeO₃/BiCrO₃ artificial superlattice, with a 1/1 stacking period. The superlattice film showed ferromagnetic behavior and polarization switching at room temperature. In the compounds, Bi³⁺ ion, located at the A site in the perovskite structure, caused ferroelectric structural distortion, and the B-site ordering of the Ni²⁺ and Mn⁴⁺ ions (Fe³⁺ and Cr³⁺ ions) in a rock-salt configuration led to ferromagnetism according to the Kanamori-Goodenough rule. Full article

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792 KiB

Open AccessArticle

Emission Enhancement in a Plasmonic Waveguide at Cut-Off

by Andrea Alù and Nader Engheta

Materials 2011, 4(1), 141-152; https://doi.org/10.3390/ma4010141 - 4 Jan 2011

Cited by 13 | Viewed by 8593

Abstract

Enhancement of molecular emission is usually obtained by coupling small optical emitters with external resonant structures and systems, as first established by Purcell several decades ago, and verified in several recent investigations using molecules or quantum dots coupled with plasmonic nanoantennas. Here we [...] Read more.

Enhancement of molecular emission is usually obtained by coupling small optical emitters with external resonant structures and systems, as first established by Purcell several decades ago, and verified in several recent investigations using molecules or quantum dots coupled with plasmonic nanoantennas. Here we theoretically investigate in detail a different mechanism for emission enhancement, based on our recent idea of a plasmonic nanolauncher [Phys. Rev. Lett. 2009, 103, 043902], i.e., a metamaterial-inspired ultranarrow waveguide channel operating near its cut-off frequency. Such system is not necessarily at resonance, but its peculiar operation may provide enhanced emission over a relatively broad physical area, which may allow enhancement of emission independent of the position of an individual or of a group of molecules along such plasmonic channel, and the possibility to bend and route the emitted energy with large flexibility. We present here extensive theoretical and numerical results that confirm this intuition and may envision a novel method for molecular emission enhancement at the nanoscale, with more flexibility than the conventional Purcell resonance techniques. Full article

(This article belongs to the Special Issue Next Wave of Metamaterials)

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1031 KiB

Open AccessArticle

¹H Nuclear Magnetic Resonance of Lodgepole Pine Wood Chips Affected by the Mountain Pine Beetle

by Tara M. Todoruk, Ian D. Hartley, Roshanak Teymoori, Jianzhen Liang and Hartwig Peemoeller

Materials 2011, 4(1), 131-140; https://doi.org/10.3390/ma4010131 - 31 Dec 2010

Cited by 2 | Viewed by 7572

Abstract

In this study, wood-water interactions of mountain pine beetle affected lodgepole pine were found to vary with time since death. Based on an analysis of magnetization components and spin-spin relaxation times from 1H NMR, it was determined that the mountain pine beetle attack [...] Read more.

In this study, wood-water interactions of mountain pine beetle affected lodgepole pine were found to vary with time since death. Based on an analysis of magnetization components and spin-spin relaxation times from 1H NMR, it was determined that the mountain pine beetle attack does not affect the crystalline structure of the wood. Both the amorphous structure and the water components vary with time since death, which could be due to the fungi present after a mountain pine beetle attack, as well as the fact that wood from the grey-stage of attack cycles seasonally through adsorption and desorption in the stand. Full article

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830 KiB

Open AccessArticle

Sub-Wavelength Resonances in Metamaterial-Based Multi-Cylinder Configurations

by Samel Arslanagić and Olav Breinbjerg

Materials 2011, 4(1), 117-130; https://doi.org/10.3390/ma4010117 - 31 Dec 2010

Cited by 2 | Viewed by 7611

Abstract

Sub-wavelength resonances known to exist in isolated metamaterial-based structures of circular cylindrical shape are investigated with the purpose of determining whether the individual resonances are retained when several of such resonant structures are grouped to form a new structure. To this end, structures [...] Read more.

Sub-wavelength resonances known to exist in isolated metamaterial-based structures of circular cylindrical shape are investigated with the purpose of determining whether the individual resonances are retained when several of such resonant structures are grouped to form a new structure. To this end, structures consisting of 1, 2 and 4 sets of metamaterial-based concentric cylinders excited by an electric line current are analyzed numerically. It is demonstrated that these structures recover the resonances of the individual structures even when the cylinders are closely spaced and the new structure is thus electrically small. The investigation is conducted through a detailed analysis of the electric near-field distribution as well as the radiation resistance in those cases where the individual structures are made of simple dielectric materials in conjunction with simple, but lossy and dispersive, metamaterials. Full article

(This article belongs to the Special Issue Next Wave of Metamaterials)

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1419 KiB

Open AccessArticle

Plasmonic Coaxial Waveguides with Complex Shapes of Cross-Sections

by Olga Kozina, Igor Nefedov, Leonid Melnikov and Antti Karilainen

Materials 2011, 4(1), 104-116; https://doi.org/10.3390/ma4010104 - 31 Dec 2010

Cited by 6 | Viewed by 9629

Abstract

In this paper, we describe waveguide properties of new optical waveguides made of noble metals and filled with glass and air. Such waveguides are coaxial cables and differ from a conventional coaxial in the shape of their central rods. Coaxial waveguide with annular [...] Read more.

In this paper, we describe waveguide properties of new optical waveguides made of noble metals and filled with glass and air. Such waveguides are coaxial cables and differ from a conventional coaxial in the shape of their central rods. Coaxial waveguide with annular and elliptic central rods are considered. Numerical simulations demonstrate that these waveguides, having nanosize cross-section, support propagation of few comparatively low-loss modes, having phase velocity close to the speed of light and the fields localized in a small area outside a metal. We illustrate excitation of these coaxial modes by dipole-like sources. Full article

(This article belongs to the Special Issue Next Wave of Metamaterials)

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17 KiB

Open AccessCorrection

Iwanaga, H. Development of Highly Soluble Anthraquinone Dichroic Dyes and Their Application to Three-Layer Guest-Host Liquid Crystal Displays. Materials 2009, 2, 1636-1661

by Hiroki Iwanaga

Materials 2011, 4(1), 103; https://doi.org/10.3390/ma4010103 - 30 Dec 2010

Viewed by 6432

Abstract

I found some mistakes on Table 2 (page 1643) in my published paper in Materials [1]. A correct table is provided here. [...] Full article

763 KiB

Open AccessReview

Optical and Electric Multifunctional CMOS Image Sensors for On-Chip Biosensing Applications

by Takashi Tokuda, Toshihiko Noda, Kiyotaka Sasagawa and Jun Ohta

Materials 2011, 4(1), 84-102; https://doi.org/10.3390/ma4010084 - 29 Dec 2010

Cited by 13 | Viewed by 10780

Abstract

In this review, the concept, design, performance, and a functional demonstration of multifunctional complementary metal-oxide-semiconductor (CMOS) image sensors dedicated to on-chip biosensing applications are described. We developed a sensor architecture that allows flexible configuration of a sensing pixel array consisting of optical and [...] Read more.

In this review, the concept, design, performance, and a functional demonstration of multifunctional complementary metal-oxide-semiconductor (CMOS) image sensors dedicated to on-chip biosensing applications are described. We developed a sensor architecture that allows flexible configuration of a sensing pixel array consisting of optical and electric sensing pixels, and designed multifunctional CMOS image sensors that can sense light intensity and electric potential or apply a voltage to an on-chip measurement target. We describe the sensors’ architecture on the basis of the type of electric measurement or imaging functionalities. Full article

(This article belongs to the Special Issue Bio-devices and Materials)

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673 KiB

Open AccessArticle

Active Microwave Metamaterials Incorporating Ideal Gain Devices

by Li-Ming Si, Tao Jiang, Kihun Chang, Te-Chuan Chen, Xin Lv, Lixin Ran and Hao Xin

Materials 2011, 4(1), 73-83; https://doi.org/10.3390/ma4010073 - 29 Dec 2010

Cited by 27 | Viewed by 10748

Abstract

Incorporation of active devices/media such as transistors for microwave and gain media for optics may be very attractive for enabling desired low loss and broadband metamaterials. Such metamaterials can even have gain which may very well lead to new and exciting physical phenomena. [...] Read more.

Incorporation of active devices/media such as transistors for microwave and gain media for optics may be very attractive for enabling desired low loss and broadband metamaterials. Such metamaterials can even have gain which may very well lead to new and exciting physical phenomena. We investigate microwave composite right/left-handed transmission lines (CRLH-TL) incorporating ideal gain devices such as constant negative resistance. With realistic lumped element values, we have shown that the negative phase constant of this kind of transmission lines is maintained (i.e., left-handedness kept) while gain can be obtained (negative attenuation constant of transmission line) simultaneously. Possible implementation and challenging issues of the proposed active CRLH-TL are also discussed. Full article

(This article belongs to the Special Issue Next Wave of Metamaterials)

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547 KiB

Open AccessReview

Surfactant Effects on Microemulsion-Based Nanoparticle Synthesis

by Concha Tojo, Miguel de Dios and Fernando Barroso

Materials 2011, 4(1), 55-72; https://doi.org/10.3390/ma4010055 - 29 Dec 2010

Cited by 43 | Viewed by 11220

Abstract

The effect of the surfactant on the size, polydispersity, type of size distribution and structure of nanoparticles synthesized in microemulsions has been studied by computer simulation. The model simulates the surfactant by means of two parameters: the intermicellar exchange parameter, k_ex, [...] Read more.

The effect of the surfactant on the size, polydispersity, type of size distribution and structure of nanoparticles synthesized in microemulsions has been studied by computer simulation. The model simulates the surfactant by means of two parameters: the intermicellar exchange parameter, k_ex, related to dimer life time, and film flexibility parameter, f, related to interdroplet channel size. One can conclude that an increase in surfactant flexibility leads to bigger and polydisperse nanoparticle sizes. In addition, at high concentrations, the same reaction gives rise to a unimodal distribution using a flexible surfactant, and a bimodal distribution using a rigid one. In relation to bimetallic nanoparticles, if the nanoparticle is composed of two metals with a moderate difference in reduction potentials, increasing the surfactant flexibility modifies the nanoparticle structure, giving rise to a transition from a nanoalloy (using a rigid film) to a core-shell structure (using a flexible one). Full article

(This article belongs to the Special Issue Nanomaterials)

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798 KiB

Open AccessArticle

Magnetization Dynamics of Amorphous Ribbons and Wires Studied by Inductance Spectroscopy

by Israel Betancourt

Materials 2011, 4(1), 37-54; https://doi.org/10.3390/ma4010037 - 23 Dec 2010

Cited by 24 | Viewed by 8748

Abstract

Inductance spectroscopy is a particular formulation variant of the well known complex impedance formalism typically used for the electric characterization of dielectric, ferroelectric, and piezoelectric materials. It has been successfully exploited as a versatile tool for characterization of the magnetization dynamics in amorphous [...] Read more.

Inductance spectroscopy is a particular formulation variant of the well known complex impedance formalism typically used for the electric characterization of dielectric, ferroelectric, and piezoelectric materials. It has been successfully exploited as a versatile tool for characterization of the magnetization dynamics in amorphous ribbons and wires by means of simple experiments involving coils for sample holding and impedance analyzer equipment. This technique affords the resolution of the magnetization processes in soft magnetic materials, in terms of reversible deformation of pinned domain walls, domain wall displacements and spin rotation, for which characteristic parameters such as the alloy initial permeability and the relaxation frequencies, indicating the dispersion of each process, can be defined. Additionally, these parameters can be correlated with chemical composition variation, size effects and induced anisotropies, leading to a more physical insight for the understanding of the frequency dependent magnetic response of amorphous alloys, which is of prime interest for the development of novel applications in the field of telecommunication and sensing technologies. In this work, a brief overview, together with recent progress on the magnetization dynamics of amorphous ribbons, wires, microwires and biphase wires, is presented and discussed for the intermediate frequency interval between 10 Hz and 13 MHz. Full article

(This article belongs to the Special Issue Amorphous Alloys)

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1032 KiB

Open AccessReview

Negative Refractive Index Metasurfaces for Enhanced Biosensing

by Zoran Jakšić, Slobodan Vuković, Jovan Matovic and Dragan Tanasković

Materials 2011, 4(1), 1-36; https://doi.org/10.3390/ma4010001 - 23 Dec 2010

Cited by 92 | Viewed by 15388

Abstract

In this paper we review some metasurfaces with negative values of effective refractive index, as scaffolds for a new generation of surface plasmon polariton-based biological or chemical sensors. The electromagnetic properties of a metasurface may be tuned by its full immersion into analyte, [...] Read more.

In this paper we review some metasurfaces with negative values of effective refractive index, as scaffolds for a new generation of surface plasmon polariton-based biological or chemical sensors. The electromagnetic properties of a metasurface may be tuned by its full immersion into analyte, or by the adsorption of a thin layer on it, both of which change its properties as a plasmonic guide. We consider various simple forms of plasmonic crystals suitable for this purpose. We start with the basic case of a freestanding, electromagnetically symmetrical plasmonic slab and analyze different ultrathin, multilayer structures, to finally consider some two-dimensional “wallpaper” geometries like split ring resonator arrays and fishnet structures. A part of the text is dedicated to the possibility of multifunctionalization where a metasurface structure is simultaneously utilized both for sensing and for selectivity enhancement. Finally we give an overview of surface-bound intrinsic electromagnetic noise phenomena that limits the ultimate performance of a metasurfaces sensor. Full article

(This article belongs to the Special Issue Next Wave of Metamaterials)

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Materials, Volume 4, Issue 1 (January 2011) – 20 articles , Pages 1-338

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