bluuebunny/crossref_metadata_2025 huggingface dataset:
Coaxial Stub Resonator for Online Monitoring Early Stages of Corrosion
Authors: Hoog Natalia A. , Mayer Mateo J.J. , Miedema Henk , Olthuis Wouter , van den Berg Albert
Published: April 2014

Here we demonstrate the proof-of-principle of a new type of flow-through sensor to assess the corrosion rate of metal surfaces. The method can be applied to all situations where metals are exposed to a corrosive (fluidic) environment, including, for instance, the interior of pipes and tubes. Our sensing device is based on the operating principle of a quarter wave length open-ended coaxial stub resonator. The method described here can be applied for on-line monitoring corrosion.
A New Surface Modifying Material "Mercaptosilatrane" for Particle Plasmon Resonance Sensor
Authors: Tseng Yen Ta , Chen Wen Hao , Chau Lai Kwan
Published: April 2014

The self-assembled monolayer (SAM) of mercaptoalkoxysilane is wildly used as a molecular linker between metal and silica. The mercapto group is known to bond with many metals, including gold, silver, copper, and lead. The mercaptoalkoxysilane system, like 3-mercaptopropyltrimethoxysilane, usually uses a concentration of 100 mM and takes 12 h in methanol or 6 h in anhydrous organic solvent,[1-3] such as toluene and benzene, to form the SAM. Unfortunately, MPTMS is very sensitive to moisture,[4, 5] generally leading to agglomeration and polymerization on a substrate during deposition, and hence multilayer deposition and irregular surface morphology. Herein, a novel concept for preparing the mercaptosilane SAM via a precursor with a silatrane head-group is proposed. We have successfully synthesized mercaptopropylsilatrane (MPS) from mercaptopropylsilane and utilized it to modify the silica surface for immobilization of gold nanoparticles (AuNPs). Results show that at a low concentration (0.46 mM) of AuNPs in aqueous solution, a good surface coverage of AuNPs can be achieved in a short time (10 min).
Humidity Sensor Based on Hetero-Core Structured Fiber Optic Covered with Layer-by-Layer Thin Film
Authors: Iwashita N. , Tomisawa J. , Seki A. , Watanabe K.
Published: April 2014

Humidity sensors based on hetero-core structured fiber optic has been fabricated. In the hetero-core structured fiber optic, a short piece of singlemode fiber optic is inserted between multi-mode fibers. Layer-by-layer (LBL) technique is applied to prepare humidity sensitive film. The humidity sensitive LBL film, prepared using polyacrylate as polyanion and polyallylamine as polycation, was deposited on the singlemode fiber part of the hetero-core structured fiber optic. According to increasing of deposition cycle, the propagating loss increased because of increasing the refractive index at the sensing part by the formation of the film. After deposition procedure, the sensor part was immersed in calcium chloride solution to dope the deliquescence material in the thin film. The humidity sensors ware characterized as a function of relative humidity (RH). The sensor shows that the propagating light power increased according to increasing of RH. This is because the dry film having a higher refractive index absorbed moisture and swollen, and then the refractive index decreased resulting in the decreasing of the leakage of the propagating light at the singlemode fiber part. In addition, the increasing of calcium chloride concentration caused the enhancement of the sensitivity. This is because calcium chloride is deliquescence material and absorbed water from atmosphere, resulting in the swelling, decreasing of the refractive index at low humidity.
Humidity Insensitive Conductometric Sensors for Ammonia Sensing
Authors: Gaudillat Pierre , Suisse Jean Moïse , Bouvet Marcel
Published: April 2014

Interest in molecular materials has been driven in large part by their various and prosperous applications, especially in the domain of organic electronics, where they offer many advantages as well as alternative approaches compared to their inorganic counterparts. Most of conductometric transducers are resistors[[ and transistors[[[, but rarely diodes[6]. In our laboratory, we designed and characterized new molecular material based devices. Molecular Semiconductor Doped Insulator (MSDI) heterojunctions were built around a heterojunction between a Molecular Semiconductor (MS) and a Doped Insulator (DI)[7][8]. This new device exhibits interesting electronic properties that allow ammonia sensing in a large humidity range at room temperature.
Differentiating among Gas Mixtures Using a Single Tin Oxide Gas Sensor
Authors: Hossein-Babaei Faramarz , Amini Amir , Babaians Khachik
Published: April 2014

Despite all their positive features oxide-based resistive gas sensors are nonselective and respond similarly for different gas and gas mixtures. The authors have recently demonstrated that the response patterns generated by a generic tin oxide gas sensor induced by thermal shocks contain considerable amounts of information regarding the nature of the present gas. Here, the results of using a similar technique on different two-component gas mixtures are reported. The gas mixtures are (1-butanol)x (2-butanol)1-x, (1-propanol)x (2-butanol)1-x, (1-butanol)x (1-propanol)1-x, and (1-butanol)0.33 (2-butanol)0.33, (1-propanol)0.33, each at various total concentrations. The diagnostic features of the response patterns were extracted, by applying wavelet transform, and used for their discrimination in a three dimensional feature space. The positions of the clusters related to different gases are consistent with their composition and facilitate estimating the individual concentrations of the components.
Preparation and Selectivity of Resistive Acetone Gas Sensors Based on Polyaniline/Au Interdigitated Electrode
Authors: Do Jing Shan , Liu Wen Long , Tsai Ming Liao , Kuo Sheng Yeng
Published: April 2014

The acetone gas sensor can be applied in the fields of the occupational safety, the prevention of fire accident and explosion in plants and the diabetic patients breathe analysis. The properties of the sensing materials and the sensing characteristics of the acetone gas sensors based on polyaniline (PANI)/Au/porous ceramic plate prepared by the microfabrication technologies and the electrochemical methods are studied in this work. PANI with stable sensing performance is prepared by a three-stage chronopotentiometric method onto Au/porous ceramic plate. The PANI nanowires are uniformly distributed on Au interdigitated electrode surface characterized by field emission scanning electron microscopy (FESEM).The sensitivity and the response time of the resistive acetone gas sensor are obtained to be 4.0×10-3 % ppm-1 and 3 min when using N2 as carrier gas. Based on the same sensing electrode, the sensitivities of the gas sensor to mixed gas containing acetone are measured.Key words: gas sensor; acetone; polyaniline; sensitivity; selectivity
Investigation of a New High Sensitive Micro-Electromechanical Strain Gauge Sensor Based on Graphene Piezoresistivity
Authors: Gamil Mohammed , Tabata Osamu , Nakamura Koichi , El-Bab Ahmed M.R. Fath , El-Moneim Ahmed Abd
Published: April 2014

A new strain gauge based on graphene piezoresistivity was fabricated by a novel low cost technique which suits mass production of micro piezoresistor sensors. The strain gauge consists of a monolayer graphene film made by chemical vapor deposition on a copper foil surface, and transferred to Si/SiO2 surface by using a polymethyl-methacrylate (PMMA) assisted transfer method. The film is shaped by laser machine to work as a conductive-piezoresistive material between two deposited electrical silver electrodes. This method of fabrication provides a high productivity due to the homogeneous distribution of the graphene monolayer all over the Si/SiO2 surface. The experimentally measured gauge factor of graphene based device is 255, which promises a new strain gauge sensor of high sensitivity.
Analysis of CO and NH3 Reductive Gases Mixture by Chemically Modified Nanocrystalline Tin Dioxide
Authors: Marikutsa Artem , Rumyantseva Marina , Gaskov Alexander
Published: April 2014

The possibility to discriminate two reducing gases CO and NH3 in their mixture by semiconductor gas sensors based on modified nanocrystalline tin dioxide was demonstrated. The selectivity was achieved by the optimization of SnO2 microstructure, surface modifier and operating temperature. Introducing catalytic clusters of palladium or ruthenium oxides increased tin dioxide sensitivity to CO at low temperature and to ammonia at raised temperature, respectively. Cross-sensing tests verified that SnO2/RuO2 sensors are selective to NH3 in comparison with CO, while SnO2/PdO displayed a complex behaviour in the presence of both gases. Possible sensor signal formation routes are discussed regarding the modifiers catalytic action and their distinctive influence on surface active sites.
IR Thermography and Resistivity Investigations on Ni-Ti Shape Memory Alloy
Authors: Costanza Girolamo , Paoloni Stefano , Tata Maria Elisa
Published: April 2014

The shape recovery efficiency of Ni-Ti shape memory springs has been investigated upon the application up to 6 X 105 thermo-activation cycles. The hysteretic behaviour of the Martensitic-Austenitic phase transition has been characterized by resistivity measurements and infrared thermography. A loss in the recovery efficiency of the original shape has been observed and has been ascribed to functional fatigue leading to the formation of the R phase upon sample heating. Nevertheless, one way shape memory effect was found to exhibit an asymptotic stable behaviour which makes possible the realization of Ni-Ti actuators able to operate for a relative large number of activation cycles.
Effect of Crack Formation under Elongation in Carbon Nanotube Networks Embedded in Polyurethane
Authors: Slobodian Petr , Riha Pavel , Benlikaya Ruhan , Olejnik Robert
Published: April 2014

A highly deformable composite composed of a network of electrically-conductive entangled carbon nanotubes embedded in elastic polyurethane for sensing tensile deformation by changes in strain has been prepared. The testing has shown that the composite can be extended as by much as 400 % during which the electrical resistance increases more than 270 times. The high strain sensing can be attributed to the network cracking upon extension. To understand the cracking mechanism and explain the resistance change, the structural changes of networks made of pristine carbon nanotubes (as well as functionalized multi-walled) were examined. The microscopic observation of crack formation and resistance change of the networks correlates well with the amount of cracking.
Enhanced Electromechanical Properties of Carbon Nanotube/Polyurethan Composite by KMnO4 Oxidation
Authors: Bořuta Roman , Slobodian Petr , Olejnik Robert , Machovsky Michal , Riha Pavel
Published: April 2014

The effect of oxidation of multi-walled carbon nanotubes by KMnO4 on the electrical resistance of a nanotube network/polyurethane composite subjected to bending has been studied. In this respect, the main achievement is a multiple increase of gauge factor for the evaluating electromechanical properties of the composite after nanotube oxidation with KMnO4. It indicates favorable properties of the composite for its use as a high-deformation strain-sensing element.
Effective Power Signal Filtering Using LC Filters with Air Core Coils
Authors: Somolinos Jose Andrés , Morales Rafael , Morón Carlos , Garcia Alfonso
Published: April 2014

Computer controlled power supplies are usually expensive when high performance (power, wide voltage range, low ripple factor and low response time) are required. This paper presents a simple and effective computer controlled DC system based on a commercial V/f inverter combined with a three-phase bridge rectifier and a LC power filter. Because of the widely variable frequency range of the V/f inverter when a wide range of voltage is required, amorphous or ferromagnetic core coils are avoided, and air core coils become an excellent solution to implement the filter and increase the efficiency of the power system. The proposed method for designing the LC filter is based on the full dynamic model of the filter-load set and the selection of the desired poles of the system according to the load to be coupled. The proposed topology lets obtain good time responses (setting time less than 100 ms) and good ripple factor (less than 1%) without any overshooting, even when low voltage output is required.
Giant Magnetoimpedance in CoP Electrodeposited Films
Authors: Morón Carlos , Tremps Enrique , Garcia Alfonso , Fuster Jose Maria , Somolinos Jose Andrés
Published: April 2014

In the last few years there has been increasing interest in CoP electrodeposited alloys due to their excellent properties as soft magnetic materials (low coercivity and high permeability) in addition to the giant magnetoimpedance that they exhibit. More recently magneto-impedance (MI) effect has also been reported on thin films obtained by sputtering techniques. Most of the studies performed on MI have been carried out on wires or ribbons, where the sensor shape was conditioned by its manufacturing process. However these limitations disappear on samples grown by sputtering or electrolysis where the geometry of sensors can be defined by using photolithographic techniques. In this work we have studied the giant magnetoimpedance in CoP films. The influence of the thickness of ferromagnetic material, conductive material, the frequency and intensity excitement and the geometric shape of the samples has been investigated.
Dislocation Density Effect on Thermal Diffusivity of AISI 316 Steel
Authors: Costanza Girolamo , Montanari Roberto , Paoloni Stefano , Tata Maria Elisa
Published: April 2014

AISI 316 steel samples have been investigated by infrared thermography (IRT) after introducing controlled degrees of plastic deformation by means of tensile tests. Microstructural examinations of the same samples showed that the progressive decrease of thermal diffusivity observed for successive steps of plastic deformation is due to the increase of dislocation density. Dislocations affect thermal diffusivity in two ways, by acting as centres of scattering and by inducing elastic stress fields. To evaluate the two contributions, IRT measurements have been also carried out in-situ, during tensile tests at progressively increasing strain. For relevant plastic deformation, the dislocations mainly affect the thermal diffusivity by scattering mechanism.
On the basis of these results, it can be concluded that thermal diffusivity is significantly affected by the increase of dislocations density therefore locally resolved IRT measurements seem promising to detect states of local plasticization in mechanical components.
Effect of Mg-Substitution on the Magnetic Properties of Cobalt Ferrite
Authors: Nlebedim I.C. , Jiles D.C.
Published: April 2014

In this study, we have substituted Mg into cobalt ferrite to investigate the effect on magnetic properties. The effect is different compared to other cation substitution studies on cobalt ferrite. An interesting observation is that the variation of magnetocrystalline anisotropy, due to Mg-substitution, is comparable with increasing Mg concentration. Similar trend was previously reported on the effect of Mg-substitution of the magnetostrictive properties of cobalt ferrite. Coercive field varies more significantly with Mg-substitution.
Single Tellurium Nanoribbon-Based NOx Gas Sensor
Authors: Jung Hyun Sung , Kim Chang Yeoul , Myung Nosang V.
Published: April 2014

We investigated sensing properties on NOx (g) of single tellurium (Te) nanoribbon-based nanodevices. The synthesized Te nanoribbons were aligned at well-defined locations using a lithographically patterned nanowire electrodeposition (LPNE) technique. The shape and length were feasibly modified by the designed lithographical pattern, and the width was tailored by the applied electrochemical parameters. Temperature-dependent electrical resistance was analyzed with as-synthesized and annealed Te nanoribbons in the temperature ranging from 15 K to 300 K, where the calculated thermal activation energies of as-synthesized and annealed Te nanoribbons were 35.7 meV and 19.2 meV, respectively. Room-temperature sensor performance of as-synthesized and annealed single Te nanoribbons on detecting NOx (g) was investigated as a function of the tailored concentration of NOx (g). Compared to a sensitivity of 16±2.9% on detecting NOx (g) of 10 ppm in the as-synthesized single Te nanoribbon sensor aligned between Au/Cr electrodes, the sensitivity of 21±3.2% on detecting NOx (g) of 10 ppm at room temperature was demonstrated by single Te nanoribbon-based sensor annealed at 200oC for 1 hour in 5 % H2/N2 (g). The effects of annealing on sensing properties have demonstrated the improved sensitivity in the annealed Te nanoribbons..
Metal Oxide Nanoparticles Obtained by Microwave Synthesis and Application in Gas Sensing by Microwave Transduction
Authors: Rossignol Jerome , Stuerga Didier
Published: April 2014

In literature, many papers describe the applications of semiconductor as sensitive material in sensor field. The gas sensor using tin oxide requires a strictly controlled high operating temperature in order to detect both reducing and oxidizing gases. The semiconductor nanoparticles, with their high specific surface area, increase the gas sensing performance. The originality of this work is to valorize the nanoparticle of metal oxide like SnO2, TiO2 obtained by microwave thermohydrolysis synthesis, using a gas sensing microwave transduction. The present synthesis is to prepare metal oxide nanocrystalline powder with a high surface area by microwave-induced thermohydrolysis. We propose to study the influence of the metal oxide nanoparticle, as a sensitive layer, in gas sensing measurement. The pollutant is added into an argon flow (dynamic regim). This work highlights a specific sensor response to each ammonia concentration at room temperature. It shows a quasi-linear relationship between the set of points of the real part of the response and the ammonia concentration. The authors are currently working on these issues as well as the interaction mechanism between adsorbed gas molecules and metal oxide films.
Damage in Composite Material: A Microwave Detection
Authors: Rossignol Jerome , Thionnet Alain
Published: April 2014

In the field of the transport, the increase of the security rule recommends to a periodic control of the structure to detect damage due to mechanical loadings. Now, current materials, used in the case of transport applications, are the composite materials. The methods, to control these materials or composite structures, need to be low cost, non-destructive, in-situ and swiftness as far as possible. The scientific literature reports many methods to control the damage in composite materials and structures. However the above requirements and the adaptation to composite materials reduce the number of methods that can be used. Currently, the adapted methods are based on infrared thermography, acoustical emission, EMIR (ElectroMagnetic InfraRed) or microwave imagery. We present an innovative non-destructive method of detecting damages in composite materials. The method is based on the observation and analysis of the modification in dielectric material resulting from damage. The originality of this method is that the diagnostic is obtained by using a microstrip resonator at microwave frequencies. The feasibility of the method is demonstrated by the detection of a fibre break into an unidirectional composite submitted to a flexural loading. The fibre break is the damage to detect. The perspective of this work is to develop a quantification and a localization of damages.
HT-XRD Analysis of W Thick Coatings for Nuclear Fusion Technology
Authors: Costanza Girolamo , Donnini R. , Kaciulis Saulius , Maddaluno Giorgio , Montanari Roberto
Published: April 2014

W is a promising material to use as protection for thermal shields in future nuclear fusion reactors, however the joining to other metals is really challenging. For realizing such joints plasma spraying (PS) has been used for its simplicity, the possibility to cover complex and extended surfaces and the relatively low cost. An appropriate interlayer must be optimized to increase the adhesion of W on the substrates and to provide a soft interface for better thermo-mechanical compatibility.The present work demonstrates that high-temperature X-ray diffraction (HT-XRD) permits to quickly assess the reliability and quality of the coating-interlayer-substrate system by measuring the strain of coating. This is very useful to orientate the work for optimizing the structure and composition of the interlayer and the parameters of deposition process.
PA-MBE Grown p-n (p-ZnO:(As+Sb)/n-GaN) and p-i-n (p-ZnO:As/HfO2/n-GaN) Heterojunctions as a Highly Selective UV Detectors
Authors: Przezdziecka Ewa , Gościński K. , Gieraltowska S. , Guziewicz E. , Jakieła R. , Kozanecki A.
Published: April 2014

Zinc oxide is a promising candidate for application in UV photodetectors due to the large direct band gap and the high absorption coefficient in the UV. The high quality p-n and p-i-n structures consist of single or dual acceptor doped ZnO:(As,Sb) films grown by MBE, thin HfO2 layer grown by ALD method and n-type GaN templates. The As and Sb concentrations is 1020 cm-3.The maximum forward-to-reverse current ratio IF/IR in the obtained p-n diodes is of about 105 at ±4 V and in the case of p-i-n diodes is of about 106, which are very good results for this type of heterojunctions. The UV photodetectors are highly selective. The maximum of the detection wavelength was found at about 365 nm (FWHM of the photocurrent peak is ~17 nm). In the case of p-i-n detectors, the maximum of detection was found at 376, 360, and 341 nm. Additionally, it is possible to control the detection range by the applied reverse voltage. The dark to light current ratio in both cases is ~104.
Enhanced Electrical Properties of PVDF-TrFE Nanocomposite for Actuator Application
Authors: Cho Kie Yong , Cho A Ra , Lee Yun Jae , Koo Chong Min , Hong Soon Man , Wang Seung Sangh , Yoon Ho Gyu , Baek Kyung Youl
Published: April 2014

Carbon nanotubes (CNTs) coated by compatibilizer (P3HT-PMMA) imparted sta-ble dispersion in organic solvents and polymer matrix (P(VDF-TrFE)). The compatibility be-tween CNTs with P3HT-PMMA was con rmed by measuring Raman spectroscopy. CoatedCNTs were then blended with P(VDF-TrFE) (70:30 mol%) to obtain polymer nanocompositesby solution- casting process. Polymer nanocomposites showed enhanced electrical characteris-tics, as nanocomposites near the threshold of the transition between P(VDF-TrFE) insulatorand CNT conductor revealed great improvement of electrical conductivity up to 10-6 S/cmat 1 KHz. Electromechanical properties of the polymer nanocomposite were examined as afunction of electric eld.
Microfluidic Biosensing Method Using the Motion of Magnetic Microparticles
Authors: Kokkinis Georgios , Dangl Alexander , Keplinger Franz , Giouroudi Ioanna
Published: April 2014

In this paper a microfluidic biosensing method for detecting a bioanalyte using the motion of magnetic microparticles (MPs) is presented. The system consists of a microfluidic channel, in which the MPs are suspended and current carrying microconductors positioned underneath the channel. These microconductors are used in order to move the MPs from the inlet to the outlet of the channel. The MPs are functionalized by modifying their surface, thus enabling them to chemically bind to a specific (non-magnetic) bioanalyte. Once the MPs binds to the bioanalyte new compounds are formed (LMPs). These compounds have a bigger overall volume than the bare MPs but still the same magnetic volume. The MPs and LMPs are manipulated inside the microfluidic channel by exposing them to magnetic field generated by the microconductors. When both, MPs and LMPs, are accelerated by the same magnetic field density, the LMPs are going to be slower than the MPs due to their increased (non-magnetic) volume. This difference in velocity is used to discriminate between MPs and LMPs. Calculations concerning the velocity change of MPs and the magnetic field generated by the current carrying microconductors were carried out. Simulations of various geometries for the conductors and various MPs were performed using finite element analysis software. Several chips were fabricated and experiments with different MPs and LMPs were conducted as a proof of concept.
Controlled Trapping and Detection of Magnetic Particles by a Magnetic Microactuator and a Giant Magnetoresistance (GMR) Sensor
Authors: Giouroudi Ioanna , Gooneratne Chinthaka , Kokkinis Georgios
Published: April 2014

This paper presents the design and testing of an integrated micro-chip for the controlled trapping and detection of magnetic particles (MPs). A unique magnetic micro-actuator consisting of square-shaped conductors is used to manipulate the MPs towards a giant magnetoresistance (GMR) sensing element which rapidly detects the majority of MPs trapped around the square-shaped conductors. The ability to precisely transport a small number of MPs in a controlled manner over long distances by magnetic forces enables the rapid concentration of a majority of MPs to the sensing zone for detection. This is especially important in low concentration samples. The conductors are designed in such a manner so as to increase the capture efficiency as well as the precision and speed of transportation. By switching current to different conductors, MPs can be manipulated and immobilized on the innermost conductor where the GMR sensor is located. This technique rapidly guides the MPs towards the sensing zone. Secondly, for optimum measurement capability with high spatial resolution the GMR sensor is fabricated directly underneath and all along the innermost conductor to detect the stray fields originating from the MPs. Finally, a microfluidic channel is fabricated on top of this micro-chip. Experiments inside the microchannel were carried out and the MPs were successfully trapped at the sensing area.
Multi-Functional Fluorescent Upconversion Nanocrystals for Simultaneous Imaging and Delivery of Peptide Toxins
Authors: Bansal Akshaya , Gnanasammandhan Muthu Kumara , Zhang Yong
Published: April 2014

The major hurdles faced by therapeutic biomolecules to reach clinical use are non-specificity, unnecessary side effects, sensitivity to environmental factors and poor cellular uptake. Several nanoparticle systems have been developed to overcome these issues but there are still some bottlenecks such as nanoparticle toxicity, bioavailability and inability to track the biomolecules post-delivery. Here we report the use of multi-functional lanthanide-based fluorescent upconversion nanoparticles as a safe delivery vector for peptides as well as for fluorescent tracking of delivery or for in-vitro/in-vivo imaging. The UCNs are excited by a NIR light source and emit in the Visible region. Since NIR light is used for excitation, the nanoparticles could be used for deep tissue imaging. Highly monodisperse uniformly sized, sub-100 nm, biocompatible upconversion nanoparticles were synthesized with a mesoporous silica coating. Amanitin, a peptide toxin was used as a model peptide and was loaded onto the mesoporous silica coated UCNs. The peptide loaded UCNs were delivered to B16F0 melanoma cells and significant cell death was achieved within 24 hours. The unloaded UCNs however had negligible toxicity. The UCNs were also used for imaging the cells with very good signal-to-noise ratio and almost nil background autofluorescence. The fluorescence from the UCNs was non-blinking, highly stable and could be used for long-term tracking.
Microstructure, Surface Characterization and Fatigue Assessment of 56SiCr7 Spring Steel
Authors: Fragoudakis Roselita , Stergioudi Fani , Michailidis Nikolaos , Savaidis G.
Published: April 2014

A high number of cycles sustained before failure, under cyclic loading application, is one of the key performance requirements of springs. Heat and surface treating of the spring steel can have a significant influence on its fatigue life. The main purpose of heat treating is to achieve a tempered-martensitic microstructure with appropriate surface hardness, in order to increase the fatigue limit of the spring. The heat treatment aims to an end martensitic formation from an initial ferritic/perlitic microstructure through the steps of heating, quenching and tempering. This study shows that the correct parameters chosen for each of these steps for 56SiCr7 steel can result to an appropriate microstructure, and therefore increase the steel surface hardness up to approximately 550-600 HV. With the aid of optical microscopy, the thickness of the decarburized surface layer is determined, in order to distinguish between the core and surface microstructure hardness of heat treated steel. Surface treatment, through shot-peening, induces compressive residual stresses on the surface of the steel, thus increasing the hardness by at least 204 HV, compared to the raw material, and doubling the number of cycles to failure. Vickers micro-hardness measurements conducted on a cross-section, at different depths from the surface of the steel, show the trend of hardness increasing towards its core, and verify the dependence of the surface hardness of the steel on heat treatment.
MOS Structures Containing Si Nanocrystals for Applications in UV Dosimeters
Authors: Arias Abraham , Nedev Nicola , Nesheva Diana , Curiel Mario , Manolov Emil , Mateos David , Dzurkov Valery , Valdez Benjamin , Contreras Oscar , Herrera Rigoberto , Bineva Irina , Siqueiros Jesus M.
Published: April 2014

Metal-Oxide-Semiconductor structures with semitransparent Au top electrode and containing Si nanocrystals in the gate dielectric are fabricated and studied. The structures can be charged negatively or positively by injecting or extracting electrons from the top electrode. Illumination with 395-400 nm, 10.4 mW UV light source causes discharge of previously charged structures with rate which varies between 2 mV/s and 12 mV/s. The discharge rate depends on the sign of the trapped charge, as well on the internal electric field in the gate dielectric.
Analysis of Signal Processing Algorithms of Coriolis Mass Flowmeters
Authors: Ruoff Jürgen , Gauchel Wolfgang , Kück Heinz
Published: April 2014

For fast and precise flow measurement using coriolis flowmeters it is necessary to accurately determinate the phase difference between two noisy position signals. These signals are digitized and filtered before being processed by phase tracking algorithms. This work investigates the influence of discretization and noise shaping on different phase tracking methods and their estimation efficiency, computational complexity, real-time performance and memory requirements.
High Sensitive and Spatial-Resolution Atom Sensor Using Two-Step Photoionization with Two-Color Near-Field Lights Generated at a Nano-Slit
Authors: Sagawa Kenta , Ito Haruhiko
Published: April 2014

We develop a nanoslit to detect a small number of neutral atoms in the ground state. The detection scheme of using two-step photoionization is very sensitive and the use of nanometric near-field lights leads to an ultrahigh spatial resolution. An edge-sharpened nanoslit is fabricated with FIB milling. Considering the case of detecting Rb atoms, the polarization-dependent spatial distribution of near-field light generated at the nanoslit by total-internal reflection of a 476.5-nm Ar-ion laser beam is obtained with a scanning near-field optical microscope. Based on the experimental results, the ionization efficiency is estimated for both s-polarization and p-polarization. We also discuss the discrepancy between the experimental value and the numerical one obtained from the finite difference time domain simulations in the p-polarization case.
Chitosan Combined with Conducting Polymers for Novel Functionality: Antioxidant and Antibacterial Activity
Authors: Kiefer Rudolf , Lee Rong Jer , Temmer Rauno , Tamm Tarmo , Aabloo Alvo
Published: April 2014

Chitosan as a natural biopolymer has applicable functionality for wound healing due to the biocompatible and antibacterial properties. Here we investigate what combined biomimetic functionality can be obtained by forming composites of chitosan and conducting polymers such as polypyrrole (PPy) or poly (3,4-ethylenedioythiophene) (PEDOT). Chemical polymerization shows direct interaction between the chitosan matrix and PPy; such materials can be dissolved as stable suspensions, coated (printed or spin coated) on fabrics or fibers with antioxidant properties of renewable activity. PEDOT and chitosan composites have shown antibacterial properties against staphylococcus aureus. The novel biocompatible chitosan conducting polymer composites will give new direction for obtaining smart materials with diverse functionality, applicable as sensors, food packaging or ion-selective membranes.
A Wireless Network of Acoustic Sensors for Environmental Monitoring
Authors: Potirakis Stelios M. , Nefzi Bilel , Tatlas Nikolas Alexander , Tuna Gurkan , Rangoussi Maria
Published: April 2014

A distributed microelectronic system for the sound/acoustic monitoring of areas of environmental interest, based on a wireless network of acoustic sensors (microphones), and the automated generation of multi-level sound maps for environmental assessment has been recently proposed. This contribution focuses on the relation between the density of the wireless nodes and node operational parameters, like the required communication rate, data compression and power autonomy, in each one of the proposed area coverage schemes/ network architectures. The results provide the grounds both for the selection of the hardware architecture on network and on node level, but also for the decision on the distribution of the processing effort between the local and the central processing units.
Electromagnetic Wave Sensing of Euglena gracilis Viability and Quantification
Authors: Mason Alex , Ozasa Kazunari , Korostynska Olga , Nakouti Ismini , Ortoneda-Pedrola Montserrat , Maeda Mizuo , Al-Shammaa Ahmed
Published: April 2014

Euglena is a naturally occurring algae which can be found in any fresh water source.It is non-toxic, easy to handle, visualize and relatively resilient to variation in environment.This, along with the relatively large size of Euglena, means it can be readily used as a modelfor environmental monitoring of other smaller pathogenic micro-organisms (e.g. Escherichiacoli ). Currently the behavior of Euglena is observed through the use of an optical microscopefor sensing purposes. However, this method su ers from following major pitfalls: (1) the sizeand expense of the microscope; (2) the small observation volume (approx. 1 L); (3) the imageprocessing requirements and (4) need for a skilled human operator to acquire those images. Byusing electromagnetic (EM) wave technology in the GHz frequency range we seek to overcomethese challenges, since it has been demonstrated by the authors to be cost e ective, have alarge sensing volume (> 100L) and produce comparatively simple output data. Furthermoreit is possible to use simple software algorithms to process the sensor output data, and providereal-time information on Euglena gracilis viability and quantity. This paper shows proof ofconcept work to verify the feasibility of the proposed EM wave technology as an alternative tothe current optical microscopy methods.
Wireless Sensor Network-Based Water Quality Monitoring System
Authors: Tuna Gurkan , Nefzi Bilel , Arkoc Orhan , Potirakis Stelios M.
Published: April 2014

Water is vital for both nature and human beings. The construction of dams and embankments, the irrigation practices, and the anthropogenic activities influence water quality. In order to control water quality, it is essential to understand the sources of pollutants. Water quality monitoring requires the collection of large numbers of samples and long delays until the results are available. Therefore, rapid monitoring of water quality is very important. In this respect, numerous systems exist for this kind of automatic monitoring. In this study, we propose a wireless sensor network (WSN)-based monitoring system controlled by a web-based online interface which allows the remote monitoring via Internet. This brings advantages over traditional monitoring systems in terms of cost effectiveness, portability and applicability. Field tests in the water reservoir of Kirklareli (Kirklareli dam), Turkey, are in progress.
The Study of Graphene Gas Sensor
Authors: Nahlik Josef , Voves Jan , Laposa Alexandr , Kroutil Jiri
Published: April 2014

The graphene is suitable for gas sensing applications for its two dimensional char-acter which gives the best possible ratio between sensor surface and volume. The interactionbetween graphene surface and gas molecules can signicantly change the graphene layer trans-port properties. Therefore graphene can serve as a sensitive layer in a gas sensor. This work isconcentrated on the analysis of the conductivity of graphene layer exposed to dierent gases(NH3, CO2 ...). Together with the electrical measurement on the interdigital graphene sensora simulation based on quantum atomistic approach has been performed. We used ATK toolkitby Quantuwise based on density functional theory (DFT) models. The exchange-correlationpotential is approximated within the generalized gradient approximation (GGA). The trans-port properties of the electrode-device- electrode geometry were calculated by means of non-equilibrium Greens function formalism as implemented in ATK. Experimental conductivitychanges are compared with the simulation results.
Analyzing the Water Budgets of Reservoirs by Using Autonomous Mini Boats
Authors: Tuna Gurkan , Arkoc Orhan , Potirakis Stelios M. , Nefzi Bilel
Published: April 2014

The calculation and estimation of water deposits in both man-made reservoirs and natural reservoirs is very important in several aspects. For surface water reservoirs in hot and dry environments, evaporation is an important factor in their operations since it can cause significant water loss. Typically, hydrologists use different computer models which take into account the effects of evaporation to estimate the water budgets of reservoirs. An important step required for this repetitive process is to calculate the current water budget of a reservoir. In this paper, an autonomous system is proposed aiming to support this step. Unlike the common approaches, the proposed system is fast and accurate, and requires no human effort. In this system, first, an autonomous mini boat follows predefined trajectories at a reservoir and builds a depth map (bathymetric map) of it. Then, an onboard computer calculates the water budget of the reservoir. The proposed system is portable and a single system can periodically serve at several water reservoirs. Field tests in the water reservoir of Kirklareli (Kirklareli dam), Turkey, are in progress.
Study on the Magnetic Hysteresis of Terfenol-D Using New Hybrid Model
Authors: Talebian Soheil , Hojjat Yousef , Ghodsi Mojtaba , Karafi Mohammad Reza
Published: April 2014

One of the main characteristics of Terfenol-d is the magnetic hysteresis, which leads to nonlinearity in mechanical-magnetic behavior. In this paper, magnetic hysteresis of Terfenol-d at different frequencies has been studied experimentally and theoretically. For experimental study, a setup has been fabricated and major hysteresis and first order reversal loops were obtained at different frequencies. Mathematical modeling of magnetic hysteresis has been done by introducing a new hybrid model which is developed by combination of Preisach and Tangent Hyperbolic models. The hybrid model can reduce the number of experiments and can be used for both frequency-independent and frequency-dependent hysteresis states.
Properties of Metal Oxide Gas Sensors with Electrodes Placed below the Sensing Layer
Authors: Durina Pavol , Plecenik Tomas , Mosko Martin , Haidry Azhar Ali , Truchly Martin , Mikula Marian , Grancic Branislav , Roch Tomas , Gregor Maros , Satrapinskyy Leonid , Kus Peter , Plecenik Andrej
Published: April 2014

In this work, we investigate the influence of position of electrodes on the sensitivity of hydrogen gas sensors based on TiO2 thin films. We have prepared two types of sensors with platinum comb-like electrodes deposited on top and under the TiO2 layer. Response of these sensors to hydrogen gas in the concentration range of 0 10 000 ppm at temperature of 350 °C has been studied. The sensors with electrodes placed under the TiO2 layer showed two orders of magnitude lower sensitivity for 10 000 ppm compared to sensors with electrodes on top of the layer, but it was considerably increased when thickness of the TiO2 layer was lowered. This gives a possibility to improve the sensitivity of gas sensors in which the electrodes must be placed below the sensing layer for their protection from harsh environment.
Thin Chitosan Films for Optical Gas Sensors
Authors: Mironenko Alexander Yuryevich , Sergeev Alexander A. , Voznesensky Sergey , Bratskaya Svetlana Y.
Published: April 2014

Here we report on fabrication of integrated-optical sensors for relative humidity and ammonia detection based on natural polysaccharide chitosan. The sensing properties of the fabricated sensor to gaseous ammonia are presented. The sensor exhibits a linear response in the range of 1-300 ppm with the response time less than 1 second. It has been shown that 1 μm-thick chitosan-based waveguide film allows highly sensitive detection of RH level.
Bi-Crystal Compensation Method for the Over-Response of Solid-State Dosimetry
Authors: Wang Ruo Xi , Pittet Patrick , Ribouton Julien , Lu Guo Neng , Galvan Jean Marc , Jalade Patrice , Balosso Jacques , Ahnesjö Anders
Published: April 2014

Solid-state dosimetry employs highly sensitive semiconductors such as Gallium Nitride (GaN) and Silicon (Si), but they have a common drawback of over response compared to tissues for low-energy scattered photons, which induces inacceptable errors for radiotherapy application. To tackle this issue, we propose a compensation method consisting in using two different materials of dosimetric interest with different atomic numbers. Their responses are denoted as SC1 and SC2. The response ratio SC1/water as a function of the ratio SC1/SC2 exhibits a monotonic curve that can serve as reference to compensate the over-response of SC1.
To validate this method, we have studied the dosimetric response of GaN (0.1 mm3) and Si crystals (2.5 mm3) by simulations, using a validated model based on the general cavity theory in a homogeneous water phantom. The dosimetric response of GaN and Si calculated using the model has errors within 2.5% compared to measured data. The local fluence spectra have been obtained by convolution of pencil beam kernel built by Monte Carlo simulations for different clinical irradiation conditions with field size (from 5×5 cm2 up to 20×20 cm2) at depth in the phantom (from 2 cm to 25 cm). The obtained results confirm a monotone relationship between GaN/water dose ratio and GaN/Si dose ratio. The reference curve is independent of irradiation conditions (field size, dosimeter position...), and allows determination of compensation value by identification.
Anisotropy of the Linear Magnetic Birefridence of Europium Iron Garnet
Authors: Tsidaeva Natalia , Abaeva Viktorija , Turiev Anatoly , Enaldieva Elena , Butkhuzi Tengiz , Khaimanov Spartak , Ramonova Alena
Published: April 2014

The results of investigation of magnetic linear birefringence (MLB) and magnetic linear dichroism (MLD) of Eu3Fe5O12 (EuIG) iron garnet on 7F07F6 optical transitions upon variation of the directions of the magnetization vector I relative to the electric vector E linearly polarized light that propagates through single crystal iron garnets are presented. The measurements were made on Eu3Fe5O12 single-crystal samples in the form of plates 100 μm thick cut in the (110) and (100) plane at the temperatures T = 82 and in a magnetic field H= 25 kOe. The absorption spectra of the linearly polarized light were studied. It is shown that MLB and dichroism in the region of the 7F07F6 absorption band reach values 10-3. First experimentally discovered nonreciprocity of MLB spectra and dichroism with the change of the relative orientation of the magnetization vector I and the light wave vector. This effect may use as a base for the design of the different transducers, for example, magnetooptical optical channels commutator.
Study of Free-Standing Electroded PZT Thick-Films: From Materials to Microsystems
Authors: Debeda Helene , Lakhmi Riadh , Pommier-Budinger Valerie , Lucat Claude
Published: April 2014

Free-standing electroded piezoelectric PZT thick-lms are straightforward fabricatedthanks to the association of the low-cost screen-printing technology with the sacricial layermethod. Au/PZT/Au bridges are directly attached onto the alumina substrate on top of it theyare processed. In addition, completely released disks are also processed. A study of the behaviourof these components shows the inuence of both the releasing process and the densicationon the piezoelectric properties of the PZT layer. From the electromechanical measurements,electroded PZT cantilevers and disks are promising for actuator, sensor or SHM applications.
The Change of the Surface Morphology of Organic Films by Laser Pulses
Authors: Turiev Anatolij M. , Tsidaeva Natalia , Ramonova Aljona , Butkhuzi Tengiz , Abaeva Victoria , Khaimanov Spartak , Enaldieva Elena
Published: April 2014

In this work by the means of atomic force microscopy (AFM) was investigated the morphology of thin films of organic molecules based on perylene and MPc, irradiated by laser radiation. It is known that the action of nanosecond laser pulse leads to a fragmentation of organic films of perylene, and MnPc derivatives. In this connection, the task was to study the surface topography of the films of perylene and MPc by the means of AFM after irradiation of them by pulsed laser radiation of nanosecond duration. The radiation source used laser with photon energy of 2.34 eV and a pulse width of 10 ns. The films were deposited on the surface of the GaAs (100) using a Knudsen cell in a vacuum 10-5 Pa. The study of the surface topography of the irradiated films was carried out under the forvacuum (10-1 Pa) using an atomic force microscope. It was discovered that modification of organic films, which manifests itself as a change in the morphology of the surface, takes place. In particular, for the first time found that the effect of laser radiation leads to an irreversible change in the topography of the surface, which is not observed with optical instruments. The comparative analysis of topography measurements of the films parts of the surface before and after laser irradiation shows, that from a certain threshold power density of 2.4 mJ/cm2, the removing of the layer from the surface of the organic film takes place, whereby the film thickness is reduced by approximately 20 nm.
FEM Simulation of Quartz Thickness Shear Mode Resonator for Gas Sensing Applications
Authors: Kulha Pavel , Laposa Igor , Laposa Alexandr , Husák Miroslav
Published: April 2014

The objective of this paper is to present simulation results of the Thickness Shear Mode (TSM) resonator based on quartz using finite element simulation method. 3D model of quartz resonator and simulations were completed using finite element method in CoventorWare software suite for design and simulation of MEMS devices. Different techniques for simulation of adsorption effect on selective layer were studied: influence of change in mass of the sensitive layer and influence of change in density of the sensitive layer. Analyses of resonant modes were performed for both cases and displacement profiles in selected modes were determined for the resonator under study. Impedance and phase characteristics were calculated and measured for clean sample and sample with selective layer coated. The adsorption model calculates the frequency shift in basic resonant frequency with adsorbed amount of sensed gas. The simulation results were used in design of gas sensors for dangerous substances detection.