bluuebunny/crossref_metadata_2025 huggingface dataset:
Preparation of MgO- and CaO-Bearing Expansive Agent Used for Cement-Based Materials
Authors: Mo Li Wu , Deng Yang , Lu An Qun , Deng Min
Published: March 2013

Blended expansive agents consisting of MgO and CaO were prepared by calcining the mixtures of dolomite and magnesite. The mineral phases and microstructures of expansive agent were examined by XRD and SEM. The expansion properties of cement pastes containing 5% and 6% of expansive agent as well as the microstructure of hydrated expansive agent in cement paste were investigated. Results indicated that the contents of MgO and CaO in the blended expansive agent could be adjusted by changing the mix proportion of dolomite and magnesite. All the cement pastes containing expansive agent produced rapid expansion. At the same addition dosage, irrespective of curing temperature, expansive agent containing higher content of MgO produced greater expansion in cement pastes, particularly at late age, which probably ascribes to the relatively slow hydration of MgO.
Influence of Steel Slag on the Workability of Concrete
Authors: Yang Jian Wei , Wang Qiang , Yan Pei Yu , Zhang Bo
Published: March 2013

The influences of steel slag on the compatibility of cement-superplasicizer system and workability of concrete were investigated in this study. Results show that there are differences among the effects of different steel slags on the fluidity of paste and workability of concrete. Steel slag is not so good as GGBS in improving the workability of concrete. Some steel slags have negative effects on the compatibility of cement-superplasicizer system by accelerating the fluidity loss of paste, but the negative effects can be weakened by adding superplasiticizer content to the saturation dosage. Concrete containing steel slag can get good workability by adding proper superplasiticizer amount.
Kinetic Study of Portland Cement Hydration with Ground Penetrating Radar
Authors: Chen Wei , Shen Pei Liang , Lu Jian Xin , Zhang Wan Ru
Published: March 2013

The variations of dielectric constant and the amplitude of reflected EM wave of concrete during the first 3 days are measured with Ground Penetrating Radar (GPR) at 20 oC. The amplitude decreases sharply after mixing with water, and then increases till a stabilized stage, followed by a gradual decline. The relative dielectric constant decreases with increasing hydrating time. The results show that the dielectric properties of concrete can be used as an effective way of studying the kinetics of concrete setting and hardening process at early ages.
Study on the Hydration Kinetics of Portland Cement
Authors: Wang Wei , Yao Wu , Wei Yong Qi
Published: March 2013

A kinetic model originally developed by Tomosawa is analyzed for the hydration of Portland cement. The complicated kinetic equation of Tomosawa model is transformed into three simple equations of simplified model which represent mass transfer, phase-boundary reaction and diffusion process at different stage, respectively. Based on the isothermal calorimetry and the simplified model, the relationship between the degree of reaction and reaction rate is discussed. The derived result could reflect the development of degree of reaction and reaction rate during the cement hydration. The calculation results of simplified model are compared well with the experimental results. Studying the connection among the three processes is helpful to understanding the complicated hydration mechanism of Portland cement.
Study on the Unhydrated Cement Grain/C-S-H Gel Interface in Cement Paste by Use of Nano-Scratch Technique
Authors: Mao Yue , Yao Wu , Xu Jing
Published: March 2013

Investigation at micro- and nano-scale is beneficial for the fundamental study of cement-based material as an extremely complex composite. This paper presents a preliminary exploration on the unhydrated cement grain/ C-S-H gel interface using nano-scratch technique. By comprehensive analysis of the penetration depth, the coefﬁcient of friction, and the elastic deformation ratio, the interfacial width of different w/c ratio and curing age were obtained, which shows a tendency to increase with the curing age in the range of 1-4 um, while has no relation to the w/c ratio.
Seismic Performance of a Multi-Span RC Highway Bridge with High Damping Rubber Bearings
Authors: Li Yong , Wang Jin Jie , Liu Jing Bo
Published: March 2013

Based on the nonlinear dynamic time history analysis, a multi-span RC highway bridge with high damping rubber bearings was studied, to investigate the damping ratio and seismic performance of the bridge and high damping rubber bearings compared with the rubber bearings. Results show that the application of high damping rubber bearings can reduce the seismic response of substructures of the bridge under longitudinal and transversal seismic excitations to some extent. But what is more important is that high damping rubber bearings wont suffer shear and displacement failure which may happen on rubber bearings. As a result, the pounding response and residual displacement can be dispelled.
A Meta-Modeling Procedure for Updating the Finite Element Model of an Arch Bridge Model
Authors: Wang De Jun , Liu Yang
Published: March 2013

Finite element (FE) model updating of structures using vibration test data has received considerable attentions in recent years due to its crucial role in fields ranging from establishing a reality-consistent structural model for dynamic analysis and control, to providing baseline model for damage identification in structural health monitoring. Model updating is to correct the analytical finite element model using test data to produce a refined one that better predict the dynamic behavior of structure. However, for real complex structures, conventional updating methods is difficult to be utilized to update the FE model of structures due to the heavy computational burden for the dynamic analysis. Meta-model is an effective surrogate model for dynamic analysis of large-scale structures. An updating method based on the combination between meta-model and component mode synthesis (CMS) is proposed to improve the efficiency of model updating of large-scale structures. The effectiveness of the proposed method is then validated by updating a scaled suspender arch bridge model using the simulated data.
In Situ Time-Resolved Energy Dispersive X-Ray Diffraction Studies of Calcium Phosphate Based Bone Cements
Authors: Rau Julietta V. , Fosca Marco , Komlev Vladimir S.
Published: March 2013

In situ monitoring of structural changes, taking place upon calcium phosphate bone cements hardening process was carried out by means of the Energy Dispersive X-Ray Diffraction method. Two different cement systems were studied, one of them based on the octacalcium phosphate and another - on the dicalcium phosphate dehydrate. Both systems contained natural biopolymer chitosan and were soaked in Simulated Body Fluid. The obtained experimental results evidence that during the hardening of the cement containing octacalcium phosphate its partial transformation into hydroxyapatite takes place, whereas no significant changes were detected during the hardening process of cement containing the dicalcium phosphate dehydrate.
Biological Characteristics of Dental Stem Cells for Tissue Engineering
Authors: Mori G. , Brunetti G. , Ballini A. , Di Benedetto A. , Tarantino U. , Colucci S. , Grano M.
Published: March 2013

Scientists have recently focused their attention on adult stem cells as new and more effective treatments for different diseases and disabilities. In fact, it is known that stem cells are capable of renewing themselves and that they can generate multiple cell types. Today, there is new evidence that stem cells are present in far more tissues and organs than once thought and that these cells are capable of developing into more kinds of cells than previously imagined. In this chapter, we focus the attention on teeth as source of stem cells. In particular, we describe the characteristic of the different types of dental stem cells and their use in tissue engineering.
Mechanical Characterization of Human Dentin: A Critical Review
Authors: Cappelloni Ilaria , Montanari Roberto
Published: March 2013

In the last years, several experimental techniques have been improved to measure mechanical properties of human dentin. Dentin exhibits a behavior like a functionally graded material with properties dependent on tubule density and orientation. This work describes and critically analyzes the elastic, anelastic and plastic characteristics of dentin on the basis of scientific literature, in particular data of Youngs modulus, shear modulus, Poissons ratio, yield and ultimate stress, hardness, fatigue, fracture toughness, creep, stress relaxation and damping have been considered. Finally, a new indentation technique (FIMEC test) is proposed to characterize the mechanical properties of dentin on a local scale.
Molecular Dynamics in Simulation of Magneto-Rheological Fluids Behavior
Authors: Barski Marek , Chwał Małgorzata , Kędziora Piotr
Published: March 2013

The present paper is devoted to computational simulations of magneto - rheological fluids behavior subjected to external magnetic fields. In order to perform these simulations the modified molecular dynamic algorithm is adopted. The theoretical model of the magneto - rheological fluid in micro scale as well as the basic interactions between the ferromagnetic particles are discussed. Moreover, the classical molecular dynamic algorithm and its necessary modifications are also described. The proposed approach makes possible to study the process of the internal structure (constructed from the ferromagnetic particles) formation under external magnetic field. The obtained results in the form of the particle distribution in the representative volume can be further used in order to evaluate the mechanical or physical properties of the fluid in macro scale, for example magnetic permeability, heat conduction, etc.
Methods of Infrared Non-Destructive Techniques: Review and Experimental Studies
Authors: Pastuszak Przemysław D. , Muc Aleksander , Barski Marek
Published: March 2013

The first part of the paper is devoted to presentation and discussion of the capabilities, advantages and limitations of infrared non-destructive techniques (IR NDT). Then, the results of experimental analysis performed by testing several specimens made of woven glass epoxy resin and containing artificial delamination in the form of square PTFE foil are presented.
Electrochemical Features of Bilirubin Oxidase Immobilized on Different Carbon Nanostructures
Authors: Filip Jaroslav , Šefčovičová Jana , Gemeiner Peter , Tkac Jan
Published: March 2013

An electrode interface was prepared using a mixture of a cheap carbon nanomaterial KetjenBlack (KB) and carbon nanotubes (CNT) dispersed in a biopolymer chitosan. Bilirubin oxidase (BOD) was proved to adsorb effectively on such a nanointerface, retaining its catalytic activity for reduction of dioxygen to water, which was proved by cyclic voltammetry. Moreover, three distinct cathodic redox reactions were determined in the absence of oxygen, suggesting that KB/CNT template provides a suitable micro and nanoporosity for direct electron transfer between BOD and the modified electrodes revealing all three known active sites of BOD. Furthermore, BOD was adsorbed on graphene oxide with subsequent electrochemical reduction of graphene oxide into a conductive graphene film with BOD trapped within the matrix. Two active sites of BOD were observed on the electrode modified by graphene suggesting the enzyme is oriented in a different way compared to the KB/CNT nanointerface due to changes in the nature of functional groups within the nanocomposite, changed porosity of the nanointerface or as a result of electrochemical perturbation of the matrix during reduction of graphene oxide. A more detailed fundamental investigation of the influence of the nanointerface matrix on an adsorption and orientation of BOD will without any doubt allow us to tailor ability of such composites to reduce dioxygen to water with high efficiency, what is a feature important for construction of robust and effective biocathodes of enzymatic biofuel cells.
Hydrogen Detection with Semimetal Graphite-ZnO (InP,GaN) Schottky Diodes
Authors: Yatskiv Roman , Zdansky Karel , Grym Jan
Published: March 2013

We investigated Schottky diode hydrogen sensors prepared by printing colloidal graphite on ZnO, GaN, and InP substrates partly covered with Pt nanoparticles. A layer of Pt nanoparticles deposited by in-situ pulsed electrophoretic deposition from isooctane colloidal solutions was inserted between the semimetal graphite and the semiconductor surface to dissociate hydrogen molecules. Schottky diodes were investigated by the measurement of current-voltage characteristics and further tested for their sensitivity to hydrogen in a cell with a through-flow gas system. The sensing elements were sensitive to gas mixture with a low hydrogen concentration down to 1 ppm.
Graphic LCD for Lightweight Electric Vehicles
Authors: Obradović Đorđe , Mihajlović Živorad , Milosavljević Vladimir , Živanov Miloš B.
Published: March 2013

In this paper, one solution of graphic LCD control board for lightweight electric vehicles is shown. The main idea was to build adoptable hardware solution that can be fast and easy applied in different electrical vehicles and easy for modifications. It was designed, built and tested graphic LCD for monitoring and seting up of main parameters and control signals for lightweight electric vehicle. Some of parameters that could be displayed on graphic LCD are charge status, actual speed, total mileage, daily mileage and indicators of direction. Also we discussed about other possibilities for some sensors that can be used to monitor vehicle speed and ways of visualizing the parameters of interest. The main principles that were used during the selection of hardware solutions implementation also are shown.
Anisotropic Magnetoresistive Study in Bilayer NiFe-NiO for Sensor Applications
Authors: Morón Carlos , Garcia Alfonso , Tremps Enrique , Somolinos Jose Andrés
Published: March 2013

Related with the detection of weak magnetic fields, the anisotropic magnetoresistive (AMR) effect is widely utilized in sensor applications. Exchange coupling between an antiferromagnet (AF) and the ferromagnet (FM) has been known as a significant parameter in the field sensitivity of magnetoresistance because of pinning effects on magnetic domain in FM layer by the bias field in AF. In this work we have studied the thermal evolution of the magnetization reversal processes in nanocrystalline exchange biased Ni80Fe20/Ni-O bilayers with large training effects and we report the anisotropic magnetoresistance ratio arising from field orientation in the bilayer.
Color Changes upon Cooling of Lepidoptera Scales Containing Photonic Nanoarchitectures
Authors: Tamáska István , Kertész Krisztián , Vértesy Zófia , Bálint Zsolt , Kun András , Yen Shen Horn , Biró László Péter
Published: March 2013

Photonic crystal type nanoarchitectures have an important advantage over conventional displays: they do not fade under solar illumination; on the contrary, more intense illumination generates more intense color. We present a simple method based on cooling in ambient air - to observe the color change of several butterfly wings colored by various photonic nanoarchitectures. The color change can be attributed to the condensation of atmospheric humidity in the nanocavities of the photonic nanoarchitecture. The effects were investigated by controlled cooling combined with the in-situ measurement of the changes in the reflectivity spectra. For certain species the reflectivity maximum (color) has almost completely disappeared. A correlation was also found between the openness of the nanostructure and the time of the color change. Cooling experiments, using thin copper wires showed that color alteration could be limited to millimeters; this may offer a possible alternative for display technology.
Synthesis of Eu-Doped TiO2 Nanotubes Using Electrochemical Oxidation
Authors: Oh Han Jun , Lee Jong Ho , Lee Seung Hyun , Chi Choong Soo
Published: March 2013

To improve the photocatalytic properties of titania photocatalyst by incorporated Eu element during electrochemical oxidation, Eu-doped titanium oxide nanotube was synthesized by anodic process in an ethylene glycol electrolyte with Eu (NO3)3 as an additive. The crystalline structure and surface characteristics of Eu-doped titania nanotube were investigated. The XPS results indicate the migration of the europium element into the titania nanotube layer from mixture electrolyte during electrochemical oxidation. The Eu-doped titania nanotubes show much higher activity of dye degradation.
Biosafety Evaluation of Nanoparticles in View of Genotoxicity and Carcinogenicity Studies: A Systematic Review
Authors: Turkez Hasan , Celik Kubra , Cakmak Bulent
Published: March 2013

Nanoparticles (NPs) are used in various forms in consumer products including, cosmetics, food packaging, textiles and also in air and water cleaning, production of electro chromic windows, or smart windows and gas sensors. Many NPs have also been evaluated for potential use in biomedical applications as efficient delivery carriers for cancer diagnosis and therapy. Nowadays, NPs are being developed to create fascinating nanotechnology products. To develop NPs for broad applications, potential risks to human health and the environment should be evaluated and taken into consideration. Again, to translate these nanomaterials to the clinic and industrial domains, their biosafety needs to be verified, particularly in terms of genotoxic and carcinogenic effects. To evaluate evidenced-based practices for NPs safety, we performed a systematic review of the published English-language literature. We performed a systematic keyword search of PubMed for original research articles pertaining to reports on assessment of risks due to carcinogenic and mutagenic effects by different NPs. We identified 362 original articles available for analysis. The included studies were published between 1993 and 2012. The in vivo or in vitro genotoxicity studies were performed on only 18 out of 148 kinds of NPs in industry today. Likewise, the carcinogenicity investigations were performed on only 14 out of 148 NPs. The 10 types of the NPs including some titanium, aluminium, carbon black and silver molecules were found to have both mutagenic and carcinogenic potential. The important finding was also that there is a lack of systematic assessment of the DNA damaging and carcinogenic potential of NPs in spite of their extensive use in nanotechnological applications.
Mechanical, Electrical and Thermal Characterization of Commercially Available LTCC Dielectric Tapes
Authors: Radosavljević Goran , Blaž Nelu , Marić Andrea , Smetana W. , Živanov Ljiljana
Published: March 2013

Presented paper deals with mechanical and electrical properties of several commercially available LTCC (Low Temperature Co-fired Technology) tapes, as well as their thermal characterization. Three commercially available dielectric tape materials provided by Heraeus (CT700, CT707 and CT800) are investigated. The samples for determination of significant material parameters are prepared using the standard LTCC fabrication process. Results of the material characterization (chemical analysis, surface roughness electrical and mechanical properties) are presented. In addition thermo-electrical and-mechanical characterization of investigated tapes analysis is performed.
Numerical Investigation of Propagation of Ultrasonic Waves in the Waveguides with Mode Conversion
Authors: Jasiūnienė Elena , Žukauskas Egidijus , Kažys Rymantas
Published: March 2013

Ultrasonic investigation techniques are widely used in materials characterisation and non-destructive testing applications. In special cases of applications, such as investigation of properties of melted polymers, metals and hot liquids, measurements must be performed in a wide temperature range. However conventional piezoelectric transducers cannot withstand higher temperatures than the Curie temperature. Therefore in order to protect conventional ultrasonic transducers from influence of a high temperature and to avoid depolarization, measurements must be performed using special waveguides with a low thermal conductivity between the object under investigation and the ultrasonic transducer. For measurements of the material properties, such as viscoelastic properties of materials, additional shear wave transducers must be used. In this work approach how to excite both, longitudinal and shear waves using special waveguides with mode conversion, using pair of conventional ultrasonic longitudinal wave transducers is presented. In this work numerical investigation of propagation of longitudinal and shear ultrasonic waves in the waveguides with mode conversion using finite element method and CIVA software was carried out. Modelling of propagation of simultaneously generated longitudinal and shear waves using pair of longitudinal ultrasonic transducers was performed. Influence of temperature gradient to the required incidence angle of the longitudinal wave was evaluated.
Capacitance Dependence of Interdigital Capacitor on Amount and Type of Applied Liquid
Authors: Marić Andrea , Blaž Nelu , Damnjanović Mirjana S. , Radosavljević Goran , Živanov Ljiljana
Published: March 2013

In this paper design and fabrication of three types of interdigital capacitors are discussed, as well as influence of the liquid amount on their capacitance, and possibility of liquid type determination by using the fabricated structures. For faster and more reliable determination of capacitance in dependence of capacitor dimension and used substrate, a software tool called INDICON was developed. Capacitance of three structures fabricated in conventional PCB technology was determined by measuring S-parameters. Measurements were also performed by adding the exact amount of liquids on the capacitor surface. In addition, capacitance value in dependence of liquid amount is presented and possibility of applying this structure for detection of liquid amount is analyzed. Also, capacitance value in dependence of used liquid types was shown. For all measured and calculated values good agreement is achieved.
Various Designs of Meander Inductor and their Influence on LC Resonant Displacement Sensor
Authors: Blaž Nelu , Mišković Goran , Marić Andrea , Damnjanović Mirjana S. , Radosavljević Goran , Živanov Ljiljana
Published: March 2013

This paper deals with various configurations of meander inductor and their influence on characteristics of passive LC displacement sensor. Passive techniques use LC resonator to measure the parameters of interest remotely without an on-board power supply. Developed LC sensor comprises a fixed meander inductor and a movable module of mender inductor - interdigital capacitor resonant circuit, thereby causing the sensor resonant frequency to be displacement - dependent. The inductor and sensor circuits have been fabricated in PCB technology. The main goal was to find the optimal position for measurement connection pads on fixed meander inductor PCB as well as position of connection line between mender inductor and interdigital capacitor on PCB board with LC circuit. Measurements were realized on Impedance Analyzer (HP4191A) in frequency range from 10 MHz to 30 MHz, with 100 kHz step for each configuration of meander inductor. As results of these measurements the best configuration and the best sensor sensitivity for both mender inductors was determined.
An End-Type Fiber-Optic UV Sensor Covered with Mixture of Two UV Sensitive Materials
Authors: Joža Ana V. , Stupar Dragan Z. , Bajić Jovan S. , Dakić Bojan M. , Mijatović Zoran , Slankamenac Miloš P. , Živanov Miloš B.
Published: March 2013

An end-type fiber-optic UV sensor based on the principle of fluorescence is proposed and demonstrated. The sensor is made of large-core plastic optical fiber with one end covered with mixture of hot melt adhesive and small amount of chlorophyll. As sources of ultraviolet radiation solar simulator and UV lamp are used. Spectra on the sensor output are measured with spectrometer and compared for different UV light sources. Both hot melt adhesive and chlorophyll reacted to UV radiation. The peaks of fluorescent emission are obtained in visible spectrum in range of blue wavelengths (for hot melt adhesive) and in range of red wavelengths (for chlorophyll), which makes this sensor configuration a good solution for signal multiplexing.
Sensing Mechanical Properties of Solid Materials with Bimorph Piezotransducers
Authors: Wang Yung Cheng , Ko Chih Chin , Chang Tien Shu
Published: March 2013

Mechanical properties of materials, such as Young's modulus, shear modulus andlinear viscoelastic damping, are experimentally measured with a thin- lm cantilever shaker. Theexperimental apparatus consists of a bimorph piezoelectric transducer acting as an actuator togenerate base excitation to the cantilever, which is analogous to earthquake causing buildingvibration. The motion of the cantilever is monitored by a pair of ber optics to measure thedisplacements of the xed end and the sample. Linear viscoelastic properties of the materialare measured from the resonant frequencies of the vibrating cantilever. Young's modulus andshear modulus are measured from bending and torsion resonant peaks, respectively. For highloss materials, loss tangent of the materials is obtained from the Lorenzian curve t around theresonant peak. Material properties at various frequencies are measured by changing the lengthof the specimens. Furthermore, by introducing crack-like defects, the measured resonances,which may be viewed as a measure of e ective moduli, are able to be adopted to locate thecrack via the method of system identi cation.
Structure of Hydrogen Gas Sensing TiO2 Thin Films Prepared by Sol-Gel Method and their Comparison with Magnetron Sputtered Films
Authors: Plesch G. , Haidry A.A. , Gregor M. , Durina P. , Gregus J. , Truchly M. , Roch T. , Plecenik T. , Zahoran M. , Puskelova J. , Mikula M. , Grancic B. , Satrapinskyy L. , Kus P. , Plecenik A.
Published: March 2013

TiO2 thin films with a thickness of about 150 nm were deposited by spin coating method on sapphire substrate from a sol-gel system. The hydrogen sensing properties of TiO2 films annealed at various temperatures were studied and correlated with their structure, optical and electrical properties. The annealing temperatures in the range of 600 800 °C lead to anatase films with a roughness in the range of 0.6 0.9 nm. Their sensitivity towards hydrogen is low. The thin films annealed at temperatures in the range 900 1000 °C consist of rutile phase and their roughness increased to 11.7 13.5 nm. They showed good hydrogen sensitivity with optimal operating temperature 200 250 °C. The structure and sensing properties of the prepared films are compared with those synthesized with magnetron sputtering. The maximum of sensitivity was measured on the thin films with diameter of the grains about 100 nm in both cases, i.e. on thin films prepared by sol-gel method as well as on thin films prepared by magnetron sputtering. The maximum sensitivity correlates with the diameter of the grains and dont depend on the allotropy of the titanium dioxide anatase or rutile.
Low-Fluence Laser Induced Fragmentation and Desorption of 3,4,9,10-Perylenetetracarboxylic Dianhydride (PTCDA) Thin Film
Authors: Ramonova Aljona , Butkhuzi Tengiz , Abaeva Viktorija , Tvauri I.V. , Khubezhov Soslan , Tsidaeva Natalia , Turiev Anatolij M. , Magkoev Tamerlan T.
Published: March 2013

Laser-induced fragmentation and desorption of fragments of PTCDA films vacuum-deposited on GaAs (100) substrate has been studied by time-of-flight (TOF) mass spectroscopy. The main effect caused by pulsed laser light irradiation (pulse duration: 10 ns, photon energy: 2.34 eV and laser fluence ranging from 0.5 to 7 mJ/cm2) is PTCDA molecular fragmentation and desorption of the fragments formed, whereas no desorption of intact PTCDA molecule was detected. Fragments formed are perylene core C20H8, its half C10H4, carbon dioxide, carbon monoxide and atomic oxygen. All desorbing fragments have essentially different kinetic energy. The mechanism of photoinduced molecular fragmentation and desorption is discussed.
Optimization and Modeling of Ink-Jet Printed Flexible Position Sensor
Authors: Samardžić Nataša , Jeranče Nikola , Stojanović Goran
Published: March 2013

This paper presents how geometrical and technological parameters of inductive angular position sensor, fabricated on flexible substrate, influence its characteristics. In our earlier work, the angular position sensor has been already presented but for 60° stroke. In presented work, the design and optimization have been performed for 90° stroke, which is extensively used, for example, in automotive applications. For three different designs of meander rolled coils, width of segments, substrate thickness and relative distance between outer and inner coils have been changed in order to find optimal sensor structure. The proposed sensor is low-cost, easily fabricated and its parameters can be adapted for different angular strokes and applications.
Ultra Low Cost Rapid Prototyping of Diffraction Grating Remote Point Gas Sensors
Authors: Aspiotis Nikos , El Sachat Alexandros , Athanasekos Loukas , Vasileiadis Miltiadis , Mousdis Georgios , Pispas Stergios , Vainos Nikos , Riziotis Christos
Published: March 2013

A new straightforward approach for the rapid prototyping and low cost development of diffraction gratings for remote chemical gas sensing is presented. Sol gel matrices incorporating various salts, as well as specially designed polymers are employed and investigated for sensors' implementation for the detection of chemical agents under a remote point sensing scheme. The interaction between the hybrid materials and the measurands results in a reversible change of their optical characteristics that consequently modifies the gratings diffraction efficiency, resulting in an enhanced sensing ability and a stable operation.
Control, Regulation and Command System of Hydronic Radiant Floors Heating by Wireless and Energy Harvesting Sensors and Actuators
Authors: Batista Gilberto , Gaspar Pedro Dinis , Silva Pedro D.
Published: March 2013

This paper presents the development of an innovative control, regulation and command system for hydronic radiant floors, more flexible and efficient that guarantees a better thermal comfort to the user and simultaneously improves the energy efficiency of this type of heating system. The majority of the actual control of hydronic radiant floors is done by thermostats that measure the air temperature and control the actuators (pumps and valves) in order to maintain the room at the specified temperature. These systems requires the frequent adjustment of thermostats set-point in order to obtain thermal comfort as it depends on other factors than just the air temperature, such as, the air humidity, external environmental conditions, radiant temperature, among others. This paper presents a control, regulation and command solution that requires minimum user intervention, as the user only has to choose the desirable thermal comfort level. The control algorithm is based on the calculation of PMV (Predicted Mean Vote) index as defined on Thermal Comfort Standard ISO 7730. Another advantage of the proposed system is related to the wireless and energy harvesting sensors and actuators that provide much more flexibility to the system.
Fluidic Sensor Realized in the LTCC Technology
Authors: Pochia Mariana Mădălina , Blaž Nelu , Marić Andrea , Rosca Daniela , Radosavljević Goran
Published: March 2013

This paper proposes a fully embedded LTCC (Low Temperature Co-fired Technology) fluidic sensor based on capacitive effect. The proposed capacitive fluidic sensor is built up by ten laser machined ceramic tape layers carrying holes and a micro-channel. The micro-channel is placed between capacitor electrodes which are screen printed and embedded inside the substrate. The operating principle of this sensor is based on the measurement of capacitance variations evoked with different permittivity values of induced fluids. By inserting various fluids in the micro-channel, capacitance of the sensor changes according to different permittivity values. Detection of various fluids has been performed. Experimentally attained results are compared with electrical characteristics determined by analytical calculations and good agreement is achieved.
A Novel Handheld Electrochemical Analyzer System Interfaced to a Smartphone
Authors: Velusamy Vijayalakshmi , Arshak Khalil , Korostynska Olga , Al-Shamma'a Ahmed
Published: March 2013

Detailed in this paper is the design of a novel handheld electrochemical analyzer system interfaced to a smart phone, which provides versatile and cost-effective solution for real-time sensing applications. It was characterised for electron transfer events associated with chemical and biological samples. The presented design is implemented based on the Arduino nanoopen source electronics prototyping platform. The versatility of the instrument is further demonstrated by employing the electrochemical analyser to a modified electrochemical cell which formed the basis of a DNA biosensor. Cyclic voltammetry technique was used to impose a triangular waveform on an electrochemical cell and the resulting current through the cell was then monitored. The DNA biosensor generated unique electrical signals in real-time between complementary and non-complementary oligonucleotides sequences of the Bacillus cereus DNA.
The effects of hybridization and non-specific binding were compared when the probe DNA molecules were immobilized on a conducting polymer matrix. The results showed that the probe DNA immobilized using electrochemical adsorption yielded better hybridization signals compared to other immobilization methods. The performance of the DNA sensor proved to be effective in terms of selectivity, sensitivity and reproducibility of hybridization events. Analysis of these DNA probes showed that the minimum level of detection was 33.3 pg/ml.
Calibration Procedure for Magnetization Loop Tracers
Authors: Roussi Vasiliki , Vossou Clio G.
Published: March 2013

The purpose of this paper is to calibrate the magnetic field coming out of an excitation coil of certain specifications, fabricated for non-destructing testing of electrical steel sheets. Thus, a comparison between experimental and numerical analysis is discussed. For the experimental estimation of the magnetic field, a sensitive Hall sensor is used to measure the dc field at a vertical array of three selected points inside the coil. These are the lower, the middle and the upper point of the coil cross section, respectively. The magnetic field is then computed theoretically using the finite element method and the BiotSavart law. Measured results are in agreement with the calculated results of the excitation field very well, within the limits of our experimental set-up.
Metallurgical, Mechanical and Magnetic Properties of Electrical Steel Sheets in TIG and PLASMA Welding
Authors: Vourna Polykseni , Ktena Aphrodite
Published: March 2013

The influence of Tungsten Insert Gas (TIG) and Plasma welding on the microstructure, mechanical and magnetic properties of non-oriented electrical steels is presented and evaluated. Samples of sizes of 5.5 cm x 5.5cm x 2.0 mm were prepared from stock plate, installed on the welding table and welded at welding speeds and pulsed currents following a predesigned protocol. The samples microstructure was studied using SEM after standard mechanical grinding and polishing procedures. The characterization of the samples is concluded with microhardness tests and magnetic measurement (Barkhausen Noise) on TIG and Plasma welded joints in order to investigate the influence of welding on the magnetizing behavior of a high Si-alloyed grade of non-oriented electrical steel.
The Precise Measurements of Coercivity Fields of Nd-Fe Ferro-Magnets in Pulsed High Magnetic Fields up to 20T
Authors: Shimoji Hiroyasu , Nakahata Yasushi , Yamada Koji , Luo Jio lian , Todaka Takashi , Borkowski Edmund B. , Enokizono Masato
Published: March 2013

The measurements of the coercive force (Hc) of magnets are very difficult to determine as a function of the true effective fields in samples with arbitrary shapes. In this study, we tried to obtain the exact coercive force, M-H curve in high and high pulsed magnetic fields up to 20T by using a double-core pick-up. The values of Hc were found over-estimated more than 20% for the Nd-Fe magnets in comparison with those announced by the company, which coincided well with the numerical simulations by using JMAG. The two samples cut along easy and hard axis showed the same saturation magnetizations, reflected by the isotropic microstructure of the raw material.
MIP-Based Impedimetric Sensors
Authors: Lagarde Florence
Published: March 2013

Molecular imprinting technique allows the preparation of tailor-made materials with high recognition faculty towards target molecules. Molecular imprinted polymers (MIPs) are more robust, easier to manipulate and cheaper than biological receptors, constituting very attractive alternatives to biomolecules as recognition elements in the elaboration of biosensors. In this paper, the principles and advantages of MIP-based impedimetric sensors are described and some examples of application in the biological or environmental fields are given.
Frequency Dependence of Complex Permeability of Polycrystalline Ferrites Based on the Realities of Microstructure
Authors: Jankovskis Janis , Ponomarenko Nikolajs , Stepins Deniss
Published: March 2013

Complex permeability spectra of polycrystalline ferrites are analyzed on the basis of the model accounting for the effects of their grain size distribution (GSD). The model allows for explicit relation for absorption component. It shows, that by change of only one parameter (related with GSD) it is possible to turn from the relaxation to resonance character of spectrum, that spectra of ferrites, sintered at low temperature, tend to the most theoretical type - symmetrical one.
Evaluation of the Potential In Vivo Genotoxicity of Tungsten (VI) Oxide Nanopowder for Human Health
Authors: Turkez Hasan , Cakmak Bulent , Celik Kubra
Published: March 2013

Tungsten (VI) oxide particles (WO3, <100 nm particle size) are used for many purposes including production of electro chromic windows, or smart windows, x-ray screen phosphors and gas sensors in everyday life. However, the carcinogenic and genotoxic potential of this nanomaterial have not been sufficiently evaluated. Therefore, the genotoxic potential of WO3 was examined in Sprague-Dawley rat bone marrow cells by using mitotic index (MI), micronucleus (MN) and chromosome aberrations (CA) assays. Rats were orally gavaged with a single dose of WO3 (0, 25, 50 and 100 mg/kg) for 30 days. All WO3 treatments significantly decreased MI rates as compared to the control group. No increase in the incidence of CA was observed at any WO3 nanoparticle dose in the CA test although MN formation was significantly (P<0.05) increased for 50 and 100 mg/kg doses. The observed alterations in MN and MI parameters reveal that WO3 has cytotoxic and genotoxic potential and could pose environmental and human health risk.
Structural Features and Color Tunable Photoluminescence of the Binary and Ternary Layered Rare-Earth Hydroxides of (Y,Ln)2(OH)5NO3·nH2O (Ln=Tb, Eu)
Authors: Wu Xiao Li , Li Ji Guang , Li Jin Kai , Liu Shao Hong , Li Xiao Dong , Sun Xu Dong , Sakka Yoshio
Published: March 2013

A series of layered rare-earth hydroxides (LRHs) of (Y,Ln)2(OH)5NO3•nH2O ( Ln=Tb,Eu), have been synthesized via a hydrothermal route. Crystal structures and optical properties of the materials have been investigated in detail by the combined techniques of XRD, FT-IR, FE-SEM, HR-TEM, and PLE/PL spectroscopies. It is shown that Tb3+ and Eu3+ are successfully incorporated into the Y-LRH host lattice to form solid solutions. Under UV excitation, the binary (Y0.97Tb0.03)- and (Y0.97Eu0.03)-LRHs exhibit their respective characteristic photoluminescence of the Eu3+ and Tb3+ activators. The ternary (Y0.965Eu0.005Tb0.03)-LRH simultaneously shows red and green emissions and both the intensity and emission color can be adjusted by changing the excitation wavelength. Compared with (Y0.995Eu0.005)-LRH, the ternary (Y0.965Eu0.005Tb0.03)-LRH exhibits appreciably enhanced 615nm red-emission, which indicates the existence of non- radiative energy transfer from Tb3+ to Eu3+. The ternary (Y0.965Eu0.005Tb0.03)-LRH also readily undergoes anion exchange with a series of inorganic and organic anions at room temperature.
Preparation and Mechanical Properties of a Novel Biomedical Magnesium-Based Scaffold
Authors: Zhang Xue , Li Xiao Wu , Li Ji Guang , Sun Xu Dong
Published: March 2013

Magnesium has been recently recognized as a biodegradable metal for bone substitute applications. In the present work, a novel magnesium based scaffold with a specific two-layer structure was prepared for powder metallurgical process. The outer layer of the scaffold shows an interconnected porous structure, so that the fresh fluid can be easily sent into the material, allowing the ingrowth of new bone tissue. The inner compact structure reinforced by the salt particles can increase the strength of the material. Structural characterizations and mechanical tests of the materials demonstrate that the structural and mechanical properties of the magnesium-based scaffold with an appropriate salt content prepared by the current method are quite comparable to those of cancellous bone. Therefore, the magnesium-based scaffold with such a two-layer structure has the potential to serve as degradable implants for bone substitute applications.
Photoluminescence Characteristics of Sol–Gel Derived ZnTiO3 Doped with Ni2+ Ion
Authors: Yu You Hua , Xia Meng , Liu Li Li , Wu Wei Jie
Published: March 2013

ZnTiO3 doped with Ni 2+ ion has been prepared at a relatively low temperature of 600°C from the precursor derived from sol-gel process using deionized water as solvent. X-ray diffraction analysis indicates that the doped samples exhibit a hexagonal ZnTiO3 structure. From the luminescence spectra analysis, the introduction of Ni2+ ions into ZnTiO3 results in novel luminescent properties. And the relative intensity of the bands varies with the concentration of Ni2+ ions. It is demonstrated that the Ni2+ ion has taken the place of Zn2+ ion in the host lattice of ZnTiO3.
Effect of NO2 Concentration on Sensitivity for High Temperature Impedancemetric NOx Sensors
Authors: Wang Hong Qin , Liu Ge Ming , Peng Niu Sheng , Feng Tao , Xia Jin Feng , Jiang Dan Yu , Yang Xiu Chun
Published: March 2013

With the growing problem of automobile exhaust pollution, the study of automotive oxygen sensor is very meaningful, nitrogen oxides accounts for a large proportion of automobile exhaust. AC impedance spectroscopy of the NOx sensor in different temperature(500°C，600°C，700°C) and NO2 of different concentrations （100ppm，500ppm，1000ppm）in this paper, the influence of temperature and gas concentration on NOx sensors is explored.
Resonant Inspection of Ceramic Tiles
Authors: Eren Gültekin Elif , Kurama Semra , Stultz Gail , Sorensen Scott
Published: March 2013

For as long as there have been metal, steel and other materials, there have been methods and ways to inspect them. The efforts to improve these methods continue to be a work in progress. Non-destructive techniques are rapidly used to control materials’ properties during the manufacturing and using. In this study resonant inspection (RI) technique to characterize ceramic tiles was used as a nondestructive testing method (NDT). Three variables affect the resonant response of a part: mass, stiffness and damping. When production is stable and controlled, these three characteristics are consistent and predictable. Anything that creates a change in the mass, stiffness or damping of the product, including general tolerances within acceptable good parts, will change the resonance response. The resonant inspection (RI) measures the structural response of a part and evaluates it against the statistical variation from a control set of good parts to screen defects was used to determine processing differences between ceramic tiles. Ceramic tiles with different pressing pressures and sintering temperatures were prepared. Due to the processing differences, water absorption (%), apparent porosity (%) and mechanical properties of these tiles changed and the inspected properties measured conventional techniques. By measuring the resonances of ceramic tiles, the structural characteristics of these tiles were determined in a single test. The resonant inspection technique’s results compared with the results of water absorption (%), apparent porosity (%) measurements and mechanical tests. The technique based on resonant acoustic method was shown to be applicable for characterization of ceramic tiles’ processing parameters in an automated and objective fashion.
Preparation and Characterization of Al2O3-Kaolin Composite Porous Ceramic Used as Ceramic Membrane Support
Authors: Chang Qi Bing , Yang Ke , Wang Xia , Cheng Ke Kai , Wang Yong Qing , Zhou Jian Er
Published: March 2013

The high sintering temperature of Al2O3 is the main reason of the high cost of the common ceramic membrane supports. To decrease the sintering temperature, kaolin and talc were chosen as sintering aid because the reaction between kaolin, talc and Al2O3 generates cordierite. The Al2O3-cordierite porous ceramic samples were sintered in the range of 1450~1510°C. The microstructure and the bending strength of the samples were characterized. The results show that the content of kaolin is no more than 8%, the bending strength of the porous ceramic sintered at 1460°C and 1510°C are 77MPa and 153MPa, respectively. The further increases of the kaolin content result in the decrease of the bending strength and the porosity. The needle-like cordierite locates in the neck of Al2O3 grains. The reaction between kaolin and Al2O3 contributes to increasing the sintering velocity. The ceramic support using cordierite as sintering aid has the acid/alkali corrosion resistance in some degree.
Study on Performance of Ru-Ir-Ti/Ti Oxide Coating Anodes Prepared with Method of Surface Nitriding on Titanium
Authors: Qu Dong , Hu Jin , Hu Chun Feng , Wang Yu Tian , Su Lin
Published: March 2013

TiN intermediate layer was prepared by heating treatment of titanium plates under N2 flow at 800°C, and the Ru-Ir-Ti/Ti oxide coating anodes were prepared by pechini method based on the as-prepared Ti/TiN substrate. The properties of the Ru-Ir-Ti/Ti coating anodes with and without TiN intermediate layer, such as microstructure, chlorine evolution, cyclic voltammetry and accelerated life test were investigated. The results show that the method of surface nitriding on titanium-based has not a significant impact on the chlorine evolution and catalytic activity, but has a certain role in the improvement of the anodic accelerated life.