bluuebunny/crossref_metadata_2025 huggingface dataset:
Nanocrystalline TiO2 for Solar Cells and Lithium Batteries
Authors: Kavan Ladislav
Published: March 2009

Nanocrystalline TiO2 (anatase) has attracted considerable interest for applications in
photoelectrochemical solar cells. This device is based on charge injection from photoexcited
organometallic dye which is adsorbed on the TiO2 surface. Titanium dioxide can electrochemically
accommodate Li+ which is useful for a design of new Li-ion batteries. Whereas the charge storage
in anatase or rutile is based on the Li-insertion into the bulk crystal, the monoclinic TiO2(B)
exhibits an unusual pseudocapacitive Li-storage mechanism. The photoelectrochemical and Liinsertion
activity of mesoscopic TiO2 depend significantly on the electrode morphology.
Synthesis and Characterization of Mesostructured Silicas and Gold Frameworks as Active Matrices for Biomolecule Encapsulation
Authors: Iton Lennox E. , Crisci Anthony J. , Vajdova Veronika , Laible Philippe D. , Burns Christopher T. , Firestone Millicent A.
Published: March 2009

Interfacing of biomolecules to inorganic frameworks is essential for fabricating
robust, functionally integrated biocomposites that may prove useful in a wide range of
technologies including biocatalysis, biosensors or protein-based devices. Our work is directed
at developing means to integrate biomolecules into mesostructured inorganics. These
frameworks serve to both improve the mechanical stability of the proteins and to facilitate
communication with them. Toward that end, we have synthesized and characterized
mesoporous silicas and conductive metallic frameworks and have examined the encapsulation
of both soluble (cytochrome c) and membrane proteins (bacteriorhodpsin) within them.
Self-Assembled Low-Resistivity NiSi Nanowire Arrays on Epitaxial Si0.7Ge0.3 on (001)Si
Authors: Wu Wen Wei , Chen Lih Juann
Published: March 2009

Self-assembled low-resistivity NiSi nanowire arrays have been grown on relaxed
epitaxial Si0.7Ge0.3 on (001)Si. The formation of the one-dimensional ordered structure is attributed
to the nucleation of NiSi nanodots on the surface undulations induced by step bunching on the
surface of SiGe film owing to the miscut of the wafers from normal to the (001)Si direction.
Furthermore, the nanodots were connected along individual arrays and turned into nanowires with
increasing amount of Ni and a-Si. Since the periodicity of surface bunching can be tuned with
appropriate vicinality and misfit, the undulated templates promise to facilitate the growth of ordered,
catalyst-free NiSi nanowires with selected periodicity and size for utilization in high-speed Si-Ge
nanodevices.
Preparation of SiC Nanofibers by Using the Polymer Blend Technique
Authors: Correa Zormy , Murata H. , Tomizawa T. , Tenmoku K. , Oya A.
Published: March 2009

SiC nanofibers were prepared by using polymer blend and melt-spinning techniques.
Polycarbosilane (PCS) as a SiC precursor polymer was dispersed finely in novolac-phenolic resin
(PF) as a carbon precursor polymer with a ratio of PCS/PF=3/7. The polymer blend was melt-spun
continuously. The fibers were then soaked in an acid solution in order to stabilize them (to convert
into an infusible state) and finally heat-treated at 1000°C. The resulting fibers consisted of
PF-derived carbon matrix including elongated nanofibers derived from PCS. Finally, the fibers were
oxidized with nitric acid to remove the carbon matrix, and the released nanofibers were collected
with a membrane filter. The resulting nanofibers were several 100 nm in diameter and 100 μm or
more in length. They were amorphous and contained a large amount of oxygen. A part of the
nanofibers was further heated to 1500°C in a graphite tube resistance furnace, resulting in
crystallization into β-SiC. The behaviors were quite similar to those of a commercially available
SiC fibers derived from PCS. In order to obtain optimum conditions, the processes were examined.
Electrochemical Control of the Magnetic Properties of Co and CoCu/Co Nanowires
Authors: Piraux Luc , Darques M. , Michotte S.
Published: March 2009

Using appropriate electrodeposition conditions, it is shown that the structural and
magnetic properties of arrays of Co and CoCu/Co nanowires can be controlled. The hcp c axis
orientation can be oriented parallel or perpendicular to the wire axis simply by changing the pH of
the electrolytic solution and/or deposition rate. This selected orientation of the c axis leads to a
drastic change in overall magnetic anisotropy and is promising for the fabrication of spin valves
structures by electrodeposition.
Metamagnetic Transitions and Stepwise GMR in Uniaxial Fe/Cr Superlattices
Authors: Ustinov V.V. , Romashev L.N. , Milyaev M.A. , Krinitsina T.P. , Burkhanov A.M.
Published: March 2009

We investigated the structure, magnetic and magnetoresistive properties of antiferromagnetically coupled [Fe(85Å)/Cr(tCr)]12 superlattices with the Cr layers thickness tCr = 12.4 and 13.6 Å, grown simultaneously on (100)MgO and (211)MgO substrates. It is shown that the (211)MgO substrate is appropriate for the growth of (210)Fe/Cr multilayers with a strong uniaxial in-plane anisotropy. The stepwise behavior of magnetization and magnetoresistance is revealed in the case when the magnetic field is applied along the easy axis in a film plane of (211)MgO/[(210)Fe/Cr]12 superlattices. The steps on M(H) and ΔR(H)/R dependences are caused by the flip of the magnetic moments of individual Fe layers. The qualitative information about the sequence of spin-flip transitions is extracted from the comparative analysis of magnetization and magnetoresistance data.
First-Principles Approach to Mn-Doped Group IV Semiconductors: Comparison with Experiments and Outlook
Authors: Continenza Alessandra , Picozzi Silvia , Profeta Gianni , Ottaviano Luca , Passacantando Maurizio , D'Orazio Franco , Lucari Franco
Published: March 2009

We present an extensive theoretical and experimental study of the Mn-Ge dilute magnetic
semiconductor, a material which - due to its high integrability with mainstream Si technology - may
hold good promises for spintronic applications. Ab-initio calculations on several different systems
containing isolated Mn impurities as well as small clusters (up to three Mn impurities) show that
Mn has a tendency to segregate into the Ge matrix and to stabilize occupation of interstitial sites if
these are coordinated with other Mn occupying substitutional sites nearby. Several different
experimental characterizations (HRTEM, XRD, UPS, MOKE) performed on Mn ion-implanted
systems are analyzed and discussed: a close comparison betweeen experimental evidences and
density functional calculations allows a full understanding of the sample properties and to
disentagle the contributions coming from the diluted and segregated phases. The complexity of this
system shows that much has to be done still to understand the physics of these materials and to
undisclose all their possible applications.
Local Structure and Dynamic Properties of Mn Substituted Manganites Studied by EXAFS and Anelastic Spectroscopy
Authors: Castellano Carlo , Martinelli A. , Ferretti M. , Cimberle M.R. , Cantelli Rosario , Cordero Francesco
Published: March 2009

We present extended X-ray absorption fine structure (EXAFS) and anelastic spectroscopy
measurements performed on (La0.63Ca0.37)(Mn1-yMy)O3 manganites (M = Cr or Ni and y = 0.03, 0.08).
The ferromagnetic metallic phase maintains its long-range character even after Mn substitution with non-
Jahn-Teller ions, but both the doping species (Ni or Cr) lower the Curie temperature and broaden the
magnetic transition. EXAFS suggests the presence of distorted insulating zones in the framework of phase
inhomogeneity. Moreover, a strong dependence of the real part of the complex dynamic Young’s modulus
and of the elastic energy-loss coefficient on the Mn substitution is evidenced by the anelastic spectroscopy
spectra. These results confirm the correlation among local lattice disorder, dynamic and magnetic degrees
of freedom and also evidence the possibility to tune manganites physical properties acting on their chemical
composition.
A Contacting Technology to Magnetic Semiconductors
Authors: Banerjee Pushan , Ghosh B.
Published: March 2009

The present paper describes the contacting technology to the diluted magnetic semiconductor
Cd1-xMnxTe having potential applications in optoelectronic and spintronic devices. For efficient
spin injection into a spintronic material, a matching ohmic contact is the demand of the time.
Since cadmium telluride has a well-known contact problem, its manganese-doped counterpart is
also facing a similar difficulty. In the present case Cd1-xMnxTe was fabricated using thermally
assisted interdiffusion and compound formation between repeated stacked elemental layers of
manganese, cadmium and tellurium. A wet electroless deposition technique was employed to
deposit manganese doped nickel phosphide as a magnetic contact onto Cd1-xMnxTe. It appeared
that the contact resistivity improved compared to the case of gold contact. The details of the
contacting technology and the results have been described in the text of the paper.
Exchange Biasing with YMnO3 Epitaxial Films
Authors: Fontcuberta J. , Martí X. , Sánchez F. , Hrabovsky D. , Laukhin V. , Skumryev V. , Dix N. , García-Cuenca M.V. , Ferrater C. , Varela M. , Lüders U. , Bobo J.F.
Published: March 2009

We report here on the growth of epitaxial YMnO3 thin films on SrTiO3 single crystalline
substrates. We show that depending of the choice of the substrate orientation or use of suitable
(metallic) buffer layer, the epitaxial texture of the YMnO3 thin films as well as its crystallographic
phase (orthorhombic or hexagonal) can be selected. Antiferromagnetic YMnO3 films have been also
grown on ferromagnetic SrRuO3 epitaxial layers. Magnetic measurements show the existence of an
exchange bias in orthorhombic films.
Structural and Magnetotransport Properties of Coherently Strained La2/3Ca1/3MnO3 Epitaxial Thin Films
Authors: Abad LI. , Laukhin V. , Valencia S. , Varela M. , Balcells Ll. , Martínez Ben
Published: March 2009

Magnetotransport properties of very high quality fully strained epitaxial thin films of
La2/3Ca1/3MnO3 (LCMO), grown on top of SrTiO3 (STO) (001) substrates, are analyzed. As-grown
fully strained epitaxial films are ferromagnetic and metallic but exhibit depressed transport and
magnetic properties (low TC and MS). Detailed analysis of the structural and magnetotransport
properties after high temperature annealing processes, have revealed a progressive structural
relaxation, as detected by the variation of the c/a tetragonal distortion, as the annealing temperature
rises up. Nevertheless, no changes in the in-plane cell parameters are observed. Simultaneously, the
magnetic transition temperature, TC, and saturation magnetisation, MS, substantially increase
approaching values similar to that of bulk materials.
Effect of Cr Substitution on the Crystal and Magnetic Structure of (Pr0.55Ca0.45)MnO3
Authors: Martinelli A. , Ferretti M. , Castellano Carlo , Cimberle M.R. , Tropeano M. , Mondelli C.
Published: March 2009

The crystal and magnetic structures of (Pr0.55Ca0.45)(Mn1-yCry)O3 (y = 0.00, 0.03, 0.06) have
been investigated between 5 and 300 K by means of neutron powder diffraction followed by Rietveld
refinement and dc magnetic measurements. An orthorhombic-to-monoclinic phase transition occurs on
cooling in (Pr0.55Ca0.45)MnO3; at lower temperature charge ordering in the Mn sub-lattice, coupled with
orbital ordering, induces an anti-ferromagnetic (AFM) spin ordering within the monoclinic phase. Cr
substitution at the Mn site hinders the phase transition, although for the y = 0.03 sample small amounts of
the monoclinic phase co-exist at low temperature with the main phase characterized by an orthorhombic
structure. In addition Cr favours ferromagnetism (FM) participating to the double exchange mechanism. Cr
substitution prevents charge ordering, favouring double exchange and hence FM spin ordering within the
Mn sub-lattice. The Curie temperature of the Cr substituted samples is independent on the Cr content.
A Study on Spin Injection of Ferromagnetic Electrode for OLED Application
Authors: Kim Sung Jin , Lee Hyeon Jun , Kim Sung Kyu , Cho Chae Ryong , Jeong Se Young
Published: March 2009

We have investigated the magnetic effect on the electrical properties of Al and Ni
electrode based organic light-emitting devices (OLEDs). The Ni electrode-based OLEDs were
compared to Al-based OLEDs in terms of their applied magnetic fields (0.3 T). We found that for
current density-voltage on Al and Ni electrodes for OLEDs, Ni electrodes can be applied to OLEDs.
The value of magneto-impedance or the resistance ratio decreased in comparison to situations with
the absence of a magnetic field. The magneto-impedance or resistance effect indicated that the spin
polarization was preserved through the organic layer. We found that the frequency response of
magneto-impedance decreased the external magnetic field at room temperature. Electrical
characterizations of the OLEDs with spin-polarized electrodes indicated the applicability of the
ferromagnetic electrodes to organic light-emitting devices.
Helical Rosette Nanotubes: Topographical and Chemical Roles in Osteoblast Attachment
Authors: Chun Ai Lin , Webster Thomas J. , Fenniri Hicham
Published: March 2009

Success in surgical joint replacements has resulted in a huge demand amongst patients.
Coupled with the lowered average age of patients requiring hip replacements, younger patients are
demanding longer life expectancy from such devices. The increasing need and demand for more
durable implants have led to new formulations of high performance nanomaterials (materials with
basic structural units of 1-100 nm). Nanotubes in particular have shown great promise because they:
1) have sizes that approach biological structures and 2) possess efficient channels for displaying
chemistries relevant to living systems at high densities and well-controlled spatial distribution.
Helical rosette nanotubes (HRN) are a new class of soft organic nanomaterials composed of a
guanine-cytosine building block that self-assembles in aqueous environments into stable nanotubular
structures with an inner diameter of ~1.1 nm. HRN can be decorated with biologically active
chemical functionalities such as cell attracting peptide fragments. Previously, we have showed that
HRN coated Ti can enhance OB attachment. In addition, proteins were seen to interact favorably
with HRN networks in a manner favorable toward OB attachment. Furthermore, in the absence of
proteins, HRN were seen to play the role of proteins in promoting OB attachment. The studies
herein, attempt to understand the role of the lysine clusters on HRN toward OB attachment. Results
show that OB do respond to lysine and molecular orientation considerations were shown to be
important. Detailed structural considerations from molecular modeling further present the possibility
of topographical influences (nanotube network architecture) towards OB attachment.
Controlled Release of Thrombin Using Aptamer-Based Nanodevices
Authors: Beyer Stefan , Dittmer Wendy U. , Reuter Andreas , Simmel Friedrich C.
Published: March 2009

Aptamers are DNA or RNA single strands that have been selected from random pools
based on their ability to bind ligands. Like antibodies, aptamers are highly specific to their targets,
and thus have many potential uses in biomedicine and biotechnology. We report here on the
construction of a protein-binding molecular device based on a DNA aptamer, which can be
instructed to hold or release the human blood-clotting factor, α-thrombin, depending on an operator
DNA sequence addressing it. In the operation of this DNA nanodevice, the thrombin-binding DNA
aptamer is switched between a binding and a non-binding form. This is achieved by sequentially
hybridizing and removing a DNA single strand to the protein binding region of the aptamer. This
principle of operation is limited as the switching sequence is determined by the protein-binding
sequence. To overcome this limitation we introduce a DNA signal translation device that allows the
operation of aptamers with arbitrary sequences. The function of the translator is based on branch
migration and the action of the endonuclease FokI. The modular design of the translator facilitates
the adaptation of the device to various input or output sequences.
New Approaches to Lipid Bilayer Fabrication: Microfluidic Solvent Extraction and Hydrogel Encapsulation
Authors: Malmstadt Noah , Jeon Tae Joon , Nash Michael , Purnell Robert , Schmidt Jacob J.
Published: March 2009

Membrane channel proteins play crucial roles in governing the transport of material and energy
across every cellular membrane. Accordingly, they are the subjects of interest for science and
medicine as well as major targets of drug discovery efforts. Recent work has also shown their
potential as highly rapid and sensitive single molecule sensors. However, techniques conventionally
used to measure the electrical transport through these proteins can be problematic to form and are
extremely fragile, limiting the range and scope of possible studies. We have developed two new
technologies which alleviate these shortcomings: in situ encapsulation of lipid membranes in
hydrogels and automated microfluidic formation. The hydrogel encapsulated membranes are
mechanically robust and long-lived as a result of the intimate contact between the hydrogel and the
membrane, enabling measurements of single channel currents for a week or longer. The automated
microfluidic formation apparatus enables the creation and manipulation of lipid membranes and the
incorporation and measurement of channel proteins in these membranes through an entirely
computer controlled process. We are working to apply these technologies toward DNA sequencing,
drug discovery, and single molecule biophysics.
Size-Controlled Hydroxyapatite Nanoparticles as Self-Organized Organic-Inorganic Composite Materials
Authors: Zhang Jing Xian , Iwasa Mikio , Jiang Dong Liang
Published: March 2009

Sodium salt carboxymethyl cellulose (CMC) was used to prepare HAp-CMC
composites through co-precipitation process. HAp nanorods with well controlled
particle size were welll aligned along the c axis in the final composites. TEM, XRD,
FTIR analysis were used to characterized the samples. It was found that the carboxyl
groups in cellulose might be the main guiding site for the precipitation and growth of
HAp and the formation of the resulting composites.
Thermo-Intelligent Surfaces for Cell Culture
Authors: Okano Teruo
Published: March 2009

In order to avoid several complications resulted from biodegradable scaffolds or single cell
injection, we have developed “cell sheet engineering”. Our concept is novel tissue reconstruction
not from single cells but from cell sheets. In order to prepare cell sheets, temperature-responsive
culture dishes are utilized. Since temperature-responsive polymers are covalently grafted on the
dishes, various types of cells adhere and proliferate on them at 37°C, but are spontaneously
detached only by reducing temperature below 32°C without any need for proteolytic enzyme. All
the confluent cells are noninvasively harvested as a single contiguous cell sheets with intact cell-cell
junctions and deposited extracellular matrix. We have utilized these harvested cell sheets for various
tissue reconstructions including ocular surfaces, periodontal ligament, cardiac patches as well as
bladder.
Neurite Development in PC12 Cells on Nanostructured Substrates
Authors: Zhang Gui Gen , Haq Furqan , Venkatramani Anandan
Published: March 2009

We investigated the role of substrate topography on neurite development in
pheochromocytoma (PC12 cells) by culturing the cells on substrates having nanoscale pillars and
pores. In general, cells on nanopillars and nanopores developed fewer and shorter neurites as
compared to cells on smooth substrates. But in comparison between the nanopillars the nanopores,
cells on nanopores developed more and longer neurites than cells on nanopillars. These results
showed that PC12 cells were spatially aware of the difference in the nanoscale structures of the
underlying substrates and responded with differences in neurite outgrowth. This fact suggests the
possibility to use nanoscale topographic features to control neurite development in neurons.
Nano-Bio Interface - Neural & Molecular Functions
Authors: Torimitsu Keiichi
Published: March 2009

This paper briefly introduces the nano-bio related-research being carried out
in our research group. The work is based on a fusion of neuroscience and bio-molecular
science with nanotechnology. This interdisciplinary research is extremely promising for
creating a new technology and developing a new knowledge. Nano-bio research could
be a key to understanding the signal processing mechanism that lies behind memory and
the learning system in our brain. Developing a novel biocompatible device that runs
with biological functions is one of our research goals.
Preparation of Microporous, Thermosensitive Organic-Inorganic Hybrid Hydrogel with Simultaneous Control of Phase Separation and Sol-Gel Process
Authors: Sakuhara Iku , Umebayashi Eri , Suguro Kazuho , Murai Wakaaki , Morohoshi Tomohiro , Ikeda Tsukasa , Kato Norihiro
Published: March 2009

To control the microstructure and the responsive rates of hydrogels, a temperature-induced
phase separation (TIPS) method applied to an organic-inorganic hybrid hydrogel. A copolymer
between thermosensitive poly(N-isopropylacrylamide), polyNIPA, and a vinyl monomer possessing
a trimethoxysilyl group was synthesized by radical reaction. Its cross-linking could be carried out by
hydrolytic polycondensation of trimethoxysilyl groups. During both reactions, the pre-gel solution
was separated into two phases by heating above a lower critical solution temperature of the
elongating polyNIPA copolymer. The responsive rates of the microporous gel could be controlled by
characteristic diffusion path length as the thickness of micropore wall, instead of the macroscopic
sample size. Therefore, the shrinking rates of the hydrogel could be successfully maximized by fixing
the phase-separated, microporous polymer network. Besides the interconnectivity of generated pores,
the thermally triggered shrinking kinetics was investigated.
Ferrofluids and Magnetorheological Fluids
Authors: Vékás Ladislau
Published: March 2009

Composition, synthesis and structural properties of ferrofluids and magnetorheological
fluids are reviewed and compared. The similarities and main differences between the two types of
magnetically controllable fluids are outlined and exemplified in the paper. Chemical synthesis and
structural characterization of magnetizable fluids for engineering and biomedical applications are
thoroughly discussed.
Self Healing of Mechanical Damage in Metallic Materials
Authors: Shinya Norio
Published: March 2009

Long term service of the materials under stresses and at attacking environments causes
material damages, leading to fractures. Among a lot of the material damages, creep cavity and fatigue
crack are principal targets to be self healed autonomously during actual service of materials. Since the
creep cavity and the fatigue crack are generally too fine to be detected during actual service and
difficult to be repaired at the service sites. Recently self healing of creep cavity and fatigue crack has
been developed. In the developed methods, segregation and precipitation of solute atoms were
applied to self healing of the damages. The self healing methods are comparatively simple and low
cost, which may make it easy to be applied to many materials.
Multistable Textured Shell Structures
Authors: Norman A.D. , Golabchi M.R. , Seffen K.A. , Guest Simon D.
Published: March 2009

Multistable structures are a promising basis for reconfigurable systems. A multistable
structure will remain in one of its stable configurations until actuation forces it to move to another
stable configuration. This paper will describe a promising method of forming structures with useful
multiple stable states by using prestressed textured shell surfaces. Textured shell structures have
features at a scale intermediate between the global structural scale, and the material scale, and can
have some remarkable structural properties. This paper will describe two simple examples: a
globally flat, but corrugated shell, and a globally curved, doubly corrugated shell. Both structures
show additional stable equilibrium configurations that would not be possible without the textured
surface.
Friction Coefficients and Wear Rates of MoS2/Cu, BN/Cu Composites
Authors: Hashimoto Takashi , Kohri Hitoshi , Yumoto Atsushi , Shiota Ichiro
Published: March 2009

It is difficult to use an ordinary bearing in a vacuum and/or at a high temperature, because
of evaporation or deterioration of the lubricant oil. A solid lubricant, MoS2 or BN, is promising in
such condition. Recently, a thin solid lubricant film is often applied on a hard material by PVD or
CVD. The thin film is, however, easily removed when the load or friction speed is too high. On the
other hand, when the lubricant is dispersed in a matrix, the solid lubricant always exists even the
surface of the bearing is worn out. The aim of this experiment is to examine friction properties of the
composites. Cu was plated on the lubricant particles by electroless deposition. The lubricant volume
fraction (hereafter Vf) was up to 30 vol%. The Cu plated lubricant powder was hot-pressed to form
composites at 873 K under 30 MPa in a vacuum. Friction properties of composites were determined
by using a ball-on-disk type testing machine. The test was performed either in air or in a vacuum
without oil at the room temperature. The coefficients of dynamical friction of the composites were
decreased by the lubricant in the air. The effect of the lubricant was much remarkable in vacuum. The
wear rates of the composites were, however, larger than Cu in the air. On the contrary, the wear rates
of the composites were much less than one of Cu in a vacuum.
Development of Stress and Temperature Sensitive Microwires for the Sensor Applications and Tuneable Composite Materials
Authors: Zhukov Arkadi , Zhukova V. , Gonzalez J. , Panina Larissa V. , Blanco J.M.
Published: March 2009

We report on tailoring magnetic properties and giant magneto-impedance GMI in glasscoated
microwires fabricated by the Taylor-Ulitovsky method, by means of selection of their alloy
composition and/or annealing conditions. Fe-rich microwires subjected to stress annealing show the
hysteresis loops of inclined form due to induced transverse magnetic anisotropy, and hence become
suitable for GMI. The transverse anisotropy depends on the annealing conditions: temperature,
duration and stress. The application of external stress further drastically changes the shape of the
hysteresis loops and the GMI spectra. The wires with compositions Co-Fe-Ni-Si-B and Co-Fe-Cr-
Si-B are demonstrated to have a low Curie temperature (below 90oC) and pronounced temperaturedependent
magnetic properties and GMI effect. Both families of developed microwires are foreseen
for applications in high performance stress and temperature sensors as well as in tuneable sensory
composite materials. Such composites contain short pieces of microwires embedded into a
dielectric matrix and contribute to the effective ac permittivity. The latter depends on the wire
magnetic properties through the GMI effect and can be tailored to produce a microwave response
sensitive to environment: magnetic field, stress and temperature.
Tunable and Self-Sensing Microwave Composite Materials Incorporating Ferromagnetic Microwires
Authors: Makhnovskiy Dmitriy , Zhukov Arkadi , Zhukova V. , Gonzalez J.
Published: March 2009

New types of stress sensitive and magnetic field tunable microwave composite
materials are discussed where embedded short ferromagnetic microwire inclusions are used as
controllable radiative elements. The dc external magnetic field is applied to the whole composite
structure. And, the local stress is transferred to the individual microwires through the
accommodating composite matrix. The spatial and angular distributions of microwires can be
random, partly ordered, or completely ordered. For a wide frequency range, the free-space
microwave response of a wire-filled composite can be characterized by a complex effective
permittivity with resonance frequency dispersion. The latter depends on the conductive and
magnetic properties of the microwire inclusions that contribute to the ac microwire
magnetoimpedance (MI). In the vicinity of the so-called antenna resonance frequency, which is
defined by the length of microwires and matrix dielectric constant, any variations in the MI of the
microwires will result in large changes of the effective permittivity, and hence the reflection and
transmission coefficients for an incident microwave. The field or stress dependence of the effective
permittivity arises from the corresponding field or stress sensitivity of the MI in the ferromagnetic
microwires with induced circumferential or helical magnetic anisotropy, respectively. The strong
field tunable effect in the proposed composite materials can be utilized to introduce reconfigurable
microwave properties in coatings, absorbers, and randomizers, and also in new media such as
microwave metamaterials and bandgap wire structures. A maximum field tunability of 30 dB was
achieved for free-space transmission measurements when the external magnetic field changed from
zero to ~40 Oe. The stress sensitivity of reflection and transmission coefficients opens up new
possibilities for the distant non-destructive testing and evaluation of composite materials both in the
laboratory environment and large scale applications. The stress tunability of transmission
coefficient may reach up to 5-8 dB within the elastic limit. The reflection coefficient usually
demonstrates less tunability in both cases (field and stress dependent) and may require a multilayer
structure to achieve better results, but it is always strong enough for the stress sensing applications.
Thermoelectric Properties of High Density Sintered Ca3Co2O6
Authors: Uesugi Takeo , Kohri Hitoshi , Shiota Ichiro , Kato Masahiko , Ohsugi Isao J.
Published: March 2009

Ca3Co4O9 is a promising material for thermoelectric generation, as it is stable up to 1173
K in the air, and shows good thermoelectric properties. Recently, it was found that Ca3Co2O6 was
stable up to 1300 K in the air. The Ca3Co2O6 is decomposed phase of Ca3Co4O9 and the temperature
limit is higher than one of Ca3Co4O9. The electrical resistivity of Ca3Co2O6 was, however, higher
than the one of Ca3Co4O9. Not only high power generation performances but also excellent strength
is required for practical use of the thermoelectric oxide materials. Polycrystalline samples of
Ca3Co2O6 were prepared by solid-state reaction (SSR) and hot pressing (HP). Relative density of
Ca3Co2O6 (HP) was over 98%, which is larger than the one of Ca3Co2O6 (SSR). Ca3Co2O6 (HP)
showed larger strength and lower resistivity than Ca3Co2O6 (SSR). The resistivity (ρ) of Ca3Co2O6
(HP) in perpendicular to the pressurized direction decreased from 64 Ωcm to 4.0×10-2 Ωcm at the
temperature range between 373 and 1173 K. In addition, the resistivity of this sample was decreased
by heat treatment in the air. The Seebeck coefficients (S) of Ca3Co2O6 (HP) was positive value and
more than 160 μVK-1 at the temperature range between 373 and 1173 K. Ca3Co1.8M0.2O6 (M= Mn
or V) were prepared by solid state reaction and hot pressing. The resistivity of Mn-substituted
Ca3Co2O6 (HP-Mn) and V-substituted Ca3Co2O6 (HP-V) were lower than the one of
non-substituted Ca3Co2O6 (HP) at the temperature below 523 K for the Mn-substituted sample or
723 K for V-substituted sample. The latter showed the lowest value 1.53 Ωcm of all specimens at
383 K. The power factor (S2ρ-1) of Ca3Co2O6 (HP) was 88.3 μWm-1K-2, which is the largest of all
specimens at 1176 K, but S2ρ-1 of V-substituted Ca3Co2O6 (HP-V) is the largest of all specimens up
to 773 K.
Synthesis of Carbon Nanofibers as Support Layer for Metal Catalyst in a Microreactor for Three-Phase Reactions
Authors: Thakur Digvijay B. , Tiggelaar R.M. , Seshan K. , Gardeniers J.G.E. , Lefferts L.
Published: March 2009

Carbon Nanofibers (CNF) layers were synthesized nickel-based thin-films on flat fused silica
substrates. CNF synthesis was performed via thermal catalytic chemical vapor deposition of
ethylene using nickel as metal catalyst. Different underlayer metal thin films, viz. titanium, tantalum
and titanium-tungsten were tested in order to obtain stable and well-attached CNF films on fused
silica substrates. It is found in case of titanium CNFs are formed on the nickel, but due to severe
Ni/Ti inderdiffusion the titanium film looses its adhesive function, as a consequence of which the
formed CNF film detaches from the substrate. The use of tantalum or titanium-tungsten as adhesion
layer resulted in stable and well-adhered CNF films on fused silica substrates, of which the
morphology can be controlled by the growth time.
Miscibility, Isothermal Crystallization/Melting Behavior and Morphology of Poly(Trimethylene Terephthalate)/Poly(Buthylene Terephthalate) Blends
Authors: Krutphun Pongpipat , Supaphol Pitt
Published: March 2009

Blends of poly(trimethylene terephthalate) (PTT) and poly(buthylene terephthalate)
(PBT) in the amorphous state were miscible in all of the blend compositioins studied, as evidenced
by a single, composition-dependent glass-transition temperature observed for each blend
composition. The variation in the glass-transition temperature was well-predicted by the Gordon-
Taylor equation, with the fitting parameter being 1.37. The cold-crystallization (peak) temperature
increased with increasing PBT content in the blends. The subsequent melting endotherms after melt
crystallization exhibited melting point depression behavior in which the observed melting
temperatures decreased with an increasing amount of minor component of the blends. LHW and
NLHW were used to determine the equilibrium melting temperature of the blends. The values of
the overall crystallization rate parameters for these blends were all found to increase with
decreasing crystallization temperature, suggesting that these blends crystallized at low temperatures
faster than that at high temperatures. As the content of PBT was further increased, these values
dramatically decreased. This result is similar to that observed in the growth rate. From LH
secondary nucleation theory, PTT ,PBT and their blends showed the transition temperatures
between regime III and II about 194oC. Banded spherulites were observed for PTT/PBT blends.
The spacing of bands of PTT increases with increasing Tc. The body of spherulite texture is more
open with increasing PBT content. In addition, the boundary of spherulite is also changed with
composition.
Sulfonated Poly(Ether Ether Ketone)(S-PEEK) as Derived from Bisphenol-S for a Proton Exchange Membrane (PEM) in Direct Methanol Fuel Cells (DMFC)
Authors: Changkhamchom Sairung , Sirivat Anuvat
Published: March 2009

The currently used Proton Exchange Membrane (PEM) in a Direct Methanol Fuel Cell
(DMFC) is NafionÒ, an excellent proton conductor in a fully hydrated membrane. However, it has
major drawbacks, such as very high cost, and loss of conductivity at elevated temperature and low
humidity. In this work, a novel PEM based on sulfonated poly(ether ether ketone) (S-PEEK).
Poly(ether ether ketone) (PEEK) was synthesized by the nucleophilic aromatic substitution
polycondensation of Bisphonol-S and 4,4'-difluorobenzophenone for system A, and Bisphenol S and
4,4'-dichlorobenzophenone for system B. Bisphenol-S helps to increase the thermal stability due to
its high melting point (245°C). The post-sulfonation reaction was performed by using concentrated
sulfuric acid. Sulfonated poly(ether ether ketone) (S-PEEK) samples were characterized by FTIR
and 1H-NMR to confirm the chemical structure of the S-PEEK, and by TGA to investigate the
thermal property.
Preparation and Characterisation of Dense TiO2 Ceramics
Authors: Pavlova Agnese , Berzina-Cimdina Liga , Locs Janis , Loca Dagnija , Bossert Joerg
Published: March 2009

In past years scientists have interest in new specific TiO2 properties, which result from
oxygen and titanium ratio in ceramic. Recently such TiO2 applications as implantable biomaterials
in medicine and photocatalysts in purification of waste water become very significant. High
temperature vacuum treated titanium oxide ceramics become biologically active and decrease
microbiological water pollution when used as electrodes in electrochemical water treatment. In
most of these cases highly dense ceramics are requested. TiO2 low-temperature modification
anatase and TiO2 high-temperature modification rutile was used during the investigation. Different
additives were used to improve particle packing and increase green density of pressed pellets as
well as following sinter density. During the investigation it was found that green density of the
samples depends not only on powder characteristics such as particle size distribution, grain size,
mineralogical composition of raw material, quantity and nature of additives used in mass
preparation procedure but also on kind and magnitude of compaction and sintering conditions.
High Internal Phase Emulsion Foams (HIPE) Filled with Organo-Bentonite: Hybrid Organic-Inorganic Porous Clay Heterostructures (HPCH) versus Organo-Modified Bentonite (MOD)
Authors: Pakeyangkoon Pornsri , Magaraphan Rathanawan , Malakul Pomthong , Nithitanakul Manit
Published: March 2009

Organoclay derived from Na-bentonite can offer an alternative used as an inorganic
filler for high internal phase emulsiom foams. Two types of organoclay, hybrid organic–inorganic
porous clay heterostructures (HPCH), derived from organo–bentonite which prepared through
surfactant–directed assembly of tetraethoxysilane (TEOS)/methyltetraethoxysilane (MTS) into
galleries of the clay mineral, and organo-modified bentonite (MOD) treated with quaternary alkyl
ammonium cation by ion exchange reaction, were used as a reinforcing agent for
poly(divinylbenzene; DVB)polyHIPE foams in this study. Poly(DVB)polyHIPE foams filled with
organo-bentonite (MOD and HPCH) loadings of 0, 1, 3, 5, and 10 wt% were successfully prepared
using the HIPE technique. To study the effects of the organoclay on morphology, surface area, and
mechanical properties of the prepared poly(DVB)polyHIPE foams, SEM, N2 adsorption-desorption,
and a Lloyd Universal testing machine were employed. It was demonstrated that the addition of
organo-bentonite (both MOD and HPCH) into PolyHIPE foams resulted in the enhancement of
physical properties of the poly(DVB)polyHIPE foams. The incorporation of layered silicate in the
polymer matrix were supported by SEM images, which shown that the roughness of the polymer
wall surfaces appeared to increase due to the presence of organoclay. It was established that the
use of organo–bentonite, both HPCH and MOD, as inorganic filler for poly(DVB)polyHIPE, has an
effect on improving the surface area of the obtained materials. However, higher improvement in
surface properties was achieved with poly(DVB)polyHIPE filled with HPCH when compared with
poly(DVB)polyHIPE foams filled with MOD. This is because of the surface charateristic of the
HPCH which is a combination of micro– and mesoporosity between each layered of silicates and
gas molecules might be able to adsorbed into these porous structures. Mechanical properties of the
filled poly(DVB)polyHIPE foams were found to improve when compared to the neat
poly(DVB)polyHIPE. Highest Young’s modulus and compressive stress were observed at 5 wt%
organoclay loading. It was clearly demonstrated in this study that the suitable content of
Synthesis and Characterization of Nanoparticulate Strengthened Nickel Microcomponents
Authors: Wei Xue Yong , Jiang Kyle
Published: March 2009

In this study, microcomponents of nickel (Ni) based nanocomposite were obtained by
electrochemical co-deposition of Ni and alumina (Al2O3) nanoparticles into the microfabricated
photoresist moulds from a nickel sulfamate bath with the presence of multi-wall carbon nanotubes
(MWCNTs). The examination of dispersion behaviour of Al2O3 nanoparticles in nickel sulfamate
bath with MWCNTs showed that the surfaces of the fillers are positively charged in a wide range of
pH value, which favours the co-deposition of Al2O3 nanoparticles and MWCNTs with Ni. Results
of SEM and EDX characterizations showed that the Al2O3 nanoparticles were uniformly distributed
in the Ni matrix and their contents were improved with the presence of MWCNTs in the solution. It
was also found that the mechanical properties of Ni were enhanced by the nanoparticulates in the Ni
matrix.
Low Temperature Growth of ZnO Nanorods by Chemical Bath Method
Authors: Hari Parameswar , Spencer Daryl
Published: March 2009

ZnO nanorods grown by chemical bath methods are of great interest in photovoltaic and electronic
device applications because they offer low cost, low temperature deposition techniques compared to
conventional molecular beam vapor deposition and sputtering methods. Our previous studies of
ZnO nanorods grown by chemical bath technique on indium tin oxide (ITO) coated glass substrates
at 90 C for 8-10 hours resulted in uniform growth of hexagonally shaped closed nanorod
structures. We used scanning electron microscopy (SEM) and atomic force microscopy (AFM)
techniques to map changes in surface morphology of nanorods grown on various substrates.
Morphology of ZnO nanorods at temperatures 80C, 90C, 95C and 100C for 9 hours of
hydrothermal growth also resulted in hexagonal shaped nanorods of various sizes and surface
roughness. In addition, we studied the changes in surface morphology of ZnO nanorods on indium
tin oxide coated glass, aluminum coated glass, and conducting tin oxide glass substrate. In this
paper, we present quantitative data on changes in cluster size and shape of nanorods as the growth
substrate and deposition temperature are varied. We will also discuss conductivity changes of ZnO
nanorods deposited on various substrates.
Inorganic Mesoporous Membrane for Potentially Used in Proton Exchange Membrane
Authors: Kuanchaitrakul Tanita , Chirachanchai S. , Manuspiya H.
Published: March 2009

Inorganic Mesoporous Membrane is a new alternative to improve high-temperature fuel
cell performance in proton exchange membrane fuel cells (PEMFCs) to substitute for Nafion. It
possess high porosity and high specific surface areas, resulting in high proton conductivity. In this
study, niobium-modified titania and antimony/niobium-modified titania ceramic were prepared via
the sol-gel technique. The various contents of antimony, 0 to 3 wt%, and 3% niobium are
incorporated into titania to improve the porous surface condition of the ceramic particles. The
xerogels were heated at about 500°C. Inorganic membranes were prepared by using the spin-coating
technique using epoxy resin as a binder. The physical, chemical, and electrical properties of these
membranes were investigated. The XRD and Raman results showed that pure TiO2 and doped TiO2
nanoparticles obtained possess an anatase structure with mesoporosity. The specific surface area of
the doped TiO2 was higher than that of pure TiO2 and it is worth pointing out that the doping of
antimony affected the surface areas more than the doping of niobium in TiO2. Moreover, these
membranes were also tested to evaluate their potential use as an electrolyte in PEMFC by using
impedance spectroscopy, TGA, mechanical properties and water uptake.
Design and Fabrication of a MEMS AC Electric Current Sensor
Authors: Leland Eli S. , White Richard M. , Wright Paul K.
Published: March 2009

The need for energy efficiency combined with advances in compact sensor network
technologies present an opportunity for a new type of sensor to monitor electricity usage in
residential and commercial environments. A novel design for a self-powered, proximity based AC
electric current sensor has been developed. This sensor device is constructed of a piezoelectric
cantilever with a permanent magnet mounted to the cantilever's free end. When the sensor is placed
in proximity to a wire carrying AC electric current, the permanent magnet couples to the wire's
alternating magnetic field, deflecting the piezoelectric cantilever and thus producing a sinusoidal
voltage proportional to the current being measured. Analytical models were developed to predict the
magnetic forces and piezoelectric voltage output pertaining to this design. MEMS-scale cantilevers
are currently under development using a three-mask process and aluminum nitride as the active
piezoelectric material. Very small (300 μm) permanent magnets have been dispenser-printed using
magnetic powders in a polymer matrix. Previously presented meso-scale (2-3 cm3) prototype
devices exhibited sensitivities of 74 mV/A, while simulations suggest MEMS device sensitivity of
2-4 mV/A.
Three-Axis MEMS Threshold Accelerometer Switch for Enhanced Power Conservation of MEMS Sensors
Authors: Churaman Wayne A. , Currano Luke J. , Gee Danny , Zakar Eugene
Published: March 2009

A no-power 3-axis bidirectional MEMS threshold accelerometer is presented in this
paper. Threshold accelerometers of 25g, 50g, and 100g were designed and fabricated on a single
3mm chip. The design is based on a conductive spring-mass system made of Au metal layers that
close a switch between two metal contacts when the designed threshold is exceeded. We present the
MEMS threshold accelerometer switch fabrication process and provide an analytical and
experimental framework for the device performance
Fully Integrated Bridge-Type Anemometer in LTCC-Based Microfluidic Systems
Authors: Bartsch de Torres Heike , Rensch Christian , Thelemann Torsten , Müller J. , Hoffmann M.
Published: March 2009

A thick film anemometer for in situ control of the flow rate in fluidic systems was
designed, manufactured and characterized. The sensor is integrated in a retention modulus
consisting of Low Temperature Cofired Ceramics (LTCC). These materials allow the cost-effective
realisation of fluidic microsystems with integrated electronics. The challenge of the work is to
design an anemometer under the exclusive use of thick film technologies. The necessity to trim
resistors causes the external use of relevant pastes. Therefore, the use inside of a closed fluidic
system requires the leak of process gases and, at the same time, a maximal heat-insulating of the
sensor element from the substrate. Free-standing elements necessitate the control of stress due to
shrinking mismatch, TCE mismatch, density gradients and deformation during the lamination. In
the presented solution, embossed flue channels prevent blow forming on a free-standing bridge. The
anemometer has a linear sensor characteristic for flow rates up to 0.1 ml/min. The layout guarantees
that the fluid gets only in contact with the basic ceramic material, which is compatible with a wide
range of biological substances. Therefore the sensor is applicable in contact with cell fluids or PCRreagents.
Piezoelectric Properties of Sputtered AlN Thin Films and their Applications
Authors: Schmid Ulrich , Sánchez-Rojas José Luis
Published: March 2009

In this study, aluminum nitride (AlN) thin films reactively sputter deposited from an
aluminium target are characterized both under material related aspects as well as on device level for
resonantly driven gyroscopes. The first topic comprises a qualitative evaluation of the c-axis
orientation by applying a wet chemical etching procedure in phosphoric acid to specimens
synthesized under varying sputter deposition conditions. Samples with a high c-axis orientation
show a low etch rate and smooth surface characteristics on the etched areas and vice versa.
Furthermore, a quantitative determination of the piezoelectric coefficients is presented including the
impact of the silicon substrate on the change in AlN film thickness under excitation. With this
advanced approach, the d33 and the d31 coefficients are gained simultaneously with high accuracy
comparing FEM simulations and interferometric measurements. Finally, AlN are applied to bulkmicromachined
gyroscopes to stimulate the drive mode. Parasitic effects on the performance
generated by the microactuator elements are identified and potential improvements are proposed.