bluuebunny/crossref_metadata_2025 huggingface dataset:
Electrical Conductivity of Poly(3,4-Ethylenedioxythiophene)-Poly(Styrenesulfonate) Coatings on Polyacrylonitrile Nanofibers for Sensor Applications
Authors: Panapoy M. , Saengsil M. , Ksapabutr Bussarin
Published: March 2009

Conducting polyacrylonitrile (PAN) nanofiber mats were prepared by dipping non-woven nanofiber mats of PAN in the solution of poly(3,4-ethylenedioxythiophene)/poly(4-styrenesulfonate) (PEDOT/PSS). PAN nanofiber mats were fabricated via the electrospinning process. The solvent used for PEDOT/PSS was ethylene glycol and isopropanol. The morphology of the resulting PAN nanofibers and the coating layers was investigated using SEM analysis. The electrical conductivity of PEDOT/PSS coated PAN nanofiber mats was measured by the four-point probe method, for different concentrations of solvent in the PEDOT/PSS solution. An addition of ethylene glycol resulted in higher electrical conductivity of the coated mats than that of isopropanol. The resistive humidity sensing properties were also investigated. The device reproducibility was presented by vapor adsorption/desorption dynamic cycles. The reproducibility of the PEDOT/PSS coated mats was superior to that of neat PEDOT/PSS films. The response sensitivity of coated mats using isopropanol as solvent was higher than that using ethylene glycol.
SiO2-Multiwalled Carbon Nanotube Base Gas Sensor
Authors: Jesen S. , Ruangphet S. , Cheirsirikul S.
Published: March 2009

The gas sensors are fabricated from multiwalled carbon nanotube-based. The electrode is constructed from platinum (Pt) and titanium (Ti). The gas sensors are used for detecting oxygen (O2), ethyl alcohol (C2H5OH) and ammonia (NH3) by measuring the charge of their electrical capacitance. In the ratio silicon dioxide (SiO2) : carbon nanotube (MWCNTs) = 100:1 by weight, the electrical capacitance of the film layer has changed at the highest rate. The response of oxygen with concentration of 10,000 ppm, 20% of ethyl alcohol and 20% of ammonia, it is found that the electrical capacitance of thin layer has change about 34%, 60% and 70%.
Gas-Sensing Property Evaluation of Reactively Sputtered Chromium Oxide Thin Films
Authors: Oros C. , Wisitsoraat Anurat , Limsuwan Pichet , Horpathum M. , Patthanasettakul V. , Tuantranont Adisorn
Published: March 2009

Metal oxide thin film materials, including SnO2, TiO2, WO3, MoO3, ZnO, have been widely studied for gas sensing applications. However, new gas-sensing materials with distinct and diverse characteristics for new sensing applications such as electronic nose are still being explored. Presently, gas sensing properties of other metal oxides have not yet been extensively explored. Chromium oxide is an interesting metal oxide for gas sensor because of its temperature stability and moderate electrical conductivity. Nevertheless, there have been very few studies on gas sensing behaviors of this material. In this work, chromium oxide thin films were systematically studied by reactive sputtering with varying sputtering parameter including oxygen flow rate. Structural characterization by means of scanning electron microscopy and X-ray diffraction reveals that the films have sub-micometer grain-size with Rhombohedral phase of Cr2O3. Gas-sensing performances of sputtered chromium oxide thin film have been characterized toward ethanol and acetylene sensing. It was found that chromium oxide thin films exhibit p-type conductivity with increased resistance when exposed to ethanol and acetylene, which are reducing gases. In addition, sensitivity to both acetylene and ethanol tend to improve as oxygen flow rate increases. Furthermore, the chromium oxide thin films exhibit high sensitivity at moderate temperature of 250-300 °C with minimum operating temperature of 200 °C.
Ethanol Sensing Characteristics of ZnO Nanostructures Impregnated by Gold Colloid
Authors: Wongrat E. , Pimpang P. , Mangkorntong N. , Choopun Supab
Published: March 2009

ZnO nanostructures were synthesized by thermal oxidation reaction from zinc powder and then impregnated by gold colloid. The gold colloid was prepared by chemical reduction technique and had red color. The heating temperature and sintering time of thermal oxidation were 700 °C and 24 hours, respectively under oxygen atmosphere. The morphology of ZnO nanostructures and ZnO impregnated gold colloid were studied by field emission scanning electron microscope (FE-SEM). The diameter and length of pure ZnO and ZnO impregnated gold colloid were about the same value and were in the range of 100-500 nm and 2.0-7.0 µm, respectively. The ethanol sensing properties of ZnO impregnated by gold colloid were tested in ethanol atmosphere at ethanol concentrations of 1000 ppm and at an operating temperature of 260-360 °C. It was found that the sensitivity and response time were improved for gold impregnated sensor with an optimum operating temperature of 300°C due to the enhanced reaction between the ethanol and the adsorbed oxygen at an optimum temperature.
Feature Difference of Interaction between Various Organic Solvent Vapors and Metal Phthalocyanines Coated on Quartz Crystal
Authors: Hongkachern Tippavan , Suwannet W. , Jaisutti Rawat , Pratontep S. , Osotchan Tanakorn
Published: March 2009

Interaction between organic solvent vapors, zinc phthalocyanine (ZnPc) and copper phthalocyanine (CuPc) coated on quartz crystal resonators were investigated for various types of organic solvent vapors including acetone, propanol, ethanol, tetrahydrofuran, methanol, nail lacquer remover, 100 Pipers and Masterblend whiskies. The major different features of the resonance frequency shift as a function of time were extracted in order to employ in gas sensor. The sensor consists of ZnPc or CuPc thin film with the thickness of ~300 nm coated on quartz crystal with resonance frequency of 2 MHz. It used as a transducer by convert the surface adsorption into the frequency shift. When the odor interacts with ZnPc or CuPc layer, the quartz frequency normally decreases from the fundamental frequency due to the additional mass on quartz surface. The different types of organic solvent have different sensitivity to the thin film and these changing lead to the different frequency shift characteristics. The frequency shift were collected and the selected data points at the time of 5, 10, 15, 20, 70, 75, and 80 minutes after dropping alcohol were used to extract the feature by using the principal component analysis (PCA) in order to classify the type of alcohol. The PCA can be used to identify the major characteristic difference of various organic solvent interactions. The main features can be identified by the amount of the frequency shift and the decay characteristics.
Evaluation the Manufacturing Process of Silk/Gelatin Electrospun Membrane
Authors: Chao Chieh Yu , Lou Ching Wen , Lu Chao Tsang , Huang Chao Chiung , Lin Jia Horng
Published: March 2009

Electrospinning is common used in manufacturing ultrafine fibers from a polymer solution. With a high specific surface area, high porosity and good biocompatibility, the elecrospun membranes have extensive applications as biomaterials such as tissue scaffolds and for drug delivery. Silk fibroins (SF), gelatin (G) both have good biocompatibility and are non-toxic. And in previous literature, gelatin nanofiber can be successfully prepared by electrospinning, which was dissolved in formic acid. Tencel, which is extracted from wood pulp, is biodegradable, has a smooth fiber structure, can protect wounds and is irritation-free. Consequently, SF, G and Tencel are widely used in biomedical applications, such as for wound dressings and scaffolds for tissue engineering and so on. In this study, we discussed the applications of different shapes of electrospun membrane such as film, web. After that, the electrospun membrane was combined with Tencel nonwoven to fabricate composite nonwoven. Electrospinning of SF/ G was performed using formic acid as the spinning solvent. Parameters, such as electrical field (15~11 kV), spinning distance (15~7 cm), and volume ratio of SF and G, were analyzed to investigate their effects on electrospinnability and morphology of nanofiber membranes. The morphology of electrospun SF/ G nanofibers was investigated by scanning electron microscopy (SEM). Analytical demonstrate that the optimal electrospinning condition was fibers with an average diameter of 200–300 nm.
Influence of Annealing Temperature on the Properties of Nanostructure ITO Thin Films Prepared by Ion-Assisted Electron Beam Evaporation
Authors: Pokaipisit Artorn , Horprathum M. , Limsuwan Pichet
Published: March 2009

The influence of annealing temperature on the optical and electrical properties, nanostructure and surface morphology of ITO thin films prepared by ion-assisted electron beam evaporation on the glass substrates has been studied. The resistivity and transmittance spectra were measured by a four-point probe method and spectrophotometer, respectively. The nanostructure and surface morphology were examined by X-ray diffractometer and atomic force microscopy. The results show that the ITO thin films with a thickness of 200 nm is amorphous. The crystallite size and optical band gap of ITO thin films increased after annealing in vacuum at different temperatures from 200 to 350 oC. At 350 oC, high quality crystalline thin films with a crystallite size of about 30 nm were obtained. The average optical transmittance was 84% in the visible range (400-700 nm) and the resistivity of 1.34 × 10-4 W-cm was obtained at a temperature of 350 oC.
Magnetic Hysteresis Properties in Dilute Ising Ultra-Thin-Film: Monte Carlo Investigation
Authors: Laosiritaworn Yongyut
Published: March 2009

Monte Carlo simulation was used to observe the dynamic magnetic behavior of dilute Ising ultra-thin-film. The hysteresis properties were investigated as varying the non-magnetic concentration, field frequency and field amplitude where the Metropolis algorithm was used. From the results, at fixed temperature and field amplitude, the hysteresis loop increases in size with increasing frequency at low frequency region but reduces at high frequency region due to the increase of the phase-lag between magnetization and external field signals. With the inclusion of non-magnetic sites, the phase-lag shifts to higher frequency as a result of weaker magnetic interaction. In addition, the scaling relation among the hysteresis area, the field parameters and non-magnetic concentration was proposed to provide general information of how the dilution affects hysteresis properties of dilute magnetic in ultra-thin-film structure.
Mechanical Properties and Microstructure of Aramid/Al2O3/Epoxy Resin Laminated Composites
Authors: Kumfu Supreyak , Nhuapeng Wim , Thamjaree Wandee , Tunkasiri Tawee
Published: March 2009

Aramid/Al2O3/epoxy resin laminated composites were fabricated using ultrasonic mixing and casting technique. This novo material could be exhibited to the ideal mechanical properties such as high tensile strength, hardness, flexural strength and lightweight which may be used to replace metal parts in vehicles. Moreover, Al2O3 powder was mixed to epoxy resin to improve the scratch resistance. To improve the bending force and interaction between Al2O3 powder phase and epoxy resin phase, the ultrasonic mixing was used for fabricating these laminate composites. The physicals and mechanical properties such as density, hardness, impact test, wear resistance and tensile strength of the composites samples were investigated. It was found that the amounts of percent by volume of the Al2O3 have affected the properties of the laminated composites. Furthermore, microstructures of specimens were also investigated by scanning electron microscope (SEM). From the results, SEM images showed good distribution and adhesion between reinforced phase and epoxy resin matrix phase.
Manufacturing Process and Property Analysis of Sound Absorption Sandwich Board
Authors: Lou Ching Wen , Chen P. , Lin Jia Horng
Published: March 2009

Typical fabric sound absorbing materials have excellent absorbing property in high frequency, but in low frequency the absorbing performance is bad. In this study the flame retarded hollow 3D crimp PET fiber and low melting point PET fiber were used to manufacture sound absorption sandwich board (SASB). By changing the skin material of sandwich structure that the low frequency of sound absorbed will improve. The SASB was combined with two skin materials and one core material. The skin materials were manufactured into the nonwoven fabrics by needle punched and thermal compressing process. The skin materials have two different thickness (0.02 mm and 0.5mm).The core material was combined five layers of loose nonwoven fabrics and bonding by thermal compressing at the same gauge (15 mm). The sound absorbing properties of core material and sandwich board were analyzed. The sound absorbing property was evaluated using two microphone impedance tube according to ASTM E1050-98. When the skin material thickness is 0.02 mm, both of the high frequency and low frequency sound absorption was optimized. When the skin material thickness is 0.5mm, the sound absorbing property is similar to typical fabric material. The high frequency sound absorption is excellent, but the low frequency sound absorption is bad.
Manufacturing Processing of Polylactic Acid Braids as Artificial Bone Matrix
Authors: Lou Ching Wen , Lu Chao Tsang , Huang Chao Chiung , Wang H.Y. , Lin Jia Horng
Published: March 2009

In this study, the PLA plied yarn was fabricated by twisting four of PLA yarns together, then PLA plied yarn was used a 16-spindle braid machine to produce the PLA braids. PLA braids were immersed in the suspension of β-tricalcium phosphate (β-TCP), and heat treatment to improve the adhesion of β-TCP particles. PLA/β-TCP composite braids were immersed in simulated body fluid (SBF) to promote bonelike apatite production. The morphology of PLA braids were investigated by scanning electron microscopy (SEM), and the results shown that when twist coefficient was 3 of PLA plied yarn, the concentration of β-TCP suspension was 0.15 wt % and heat treatment at 175 °C for 9 min, we can obtain the optimal conditions of β-TCP particles adhesion.
Manufacture and Performance Evaluation of Elastic/Bamboo Wrapped Yarn
Authors: Chang S.P. , Lin Chin Mei , Lou Ching Wen , Hsing Wen Hao , Lin Jia Horng
Published: March 2009

Bamboo charcoal shows many advantages such as: moisture-proof foul smells reduction, the release of negative ion and far infrared ray, keep warm etc. For the purpose of increasing disersification, comfortable and beautiful feeling of the fiber efficiency, it already popularly applied to textile industry. This study used the elastic fibers as core yarn that was covered with polyester textured yarn contained bamboo charcoal to produce covered yarn. Elastic yarn was draw for suitable ratio and then covered with polyester yarn to form covered yarn, different draw ratio worked by changing roller speed, adjust twist number by controlling take up roller speed and twister speed of covering machine to get ideal stretch power were studied. Experiment results indicated that maximum break strength (4.52gw/denier) that when the speed of the rotor is 6000rpm while drawing ratio at 350%, twist number 2turns/cm. Maximum breaking elongation (24.57%) could get at speed of the rotor is 4000rpm when drawing at 350%, twist number 4.5turns/cm.
PET/PP Blend with Bamboo Charcoal to Produce Functional Composites: Evaluation of Functionalities
Authors: Lin Jia Horng , Lou Ching Wen , Chen Jin Mao , Hsieh Chien Teng , Liu Z.H.
Published: March 2009

Poly(ethylene terephthalate)/polypropylene/bamboo charcoal (PET/PP/BC) thermoplastic composites were prepared by melt compounding and then injection molding. The functionalities of the composites, such as electrical resistivity, electromagnetic shielding effectiveness (EMSE), far-infrared ray radiativity (FIRR) and negative ion concentration, were evaluated in the study. The surface resistivity and volume resistivity of the functional composites were 2.47 - 9.12×1011 Ω/sq and 5.8 - 7.01×1010 Ωcm, respectively, while composites containing 6 wt% BC or above. The EMSE of the composites were below 10 dB at frequency ranged from 300 kHz to3 GHz. The average FIRR of the composites was 0.85 at BC concentration of 8 wt%. Incorporation of BC into the composites increased the negative ion concentration of about 30 pcs/cc compared to those without BC. However, it is lower than the positive ion concentration in the air.
The Effect of Processing Parameters on Properties of Bi2GeO5 Glass Ceramics
Authors: Kantha P. , Sirisoonthorn S. , Pengpat Kamonpan
Published: March 2009

In this research, it is interesting to fabricate glass ceramics containing lead free ferroelectric crystals. The new lead free ferroelectric phase of interest is orthorhombic Bi2GeO5 which are precipitated in the BiO1.5-GeO2-BO1.5 system and studied in the region of 60 mol% BiO1.5:20 mol% GeO2: 20 mol% BO1.5. The glasses were prepared by conventional melt-quenching method. The glasses were melted separately in Pt and Al2O3 crucible in an air atmosphere. It is found that the as-received glasses were easily obtained from Al2O3 crucible while that from Pt crucible devitrification of Bi2GeO5 crystals were observed in some glasses, giving rise to an instability and difficulty in obtaining good based glasses by using this Pt crucible. The glass ceramics prepared from Pt crucible crystallized into two phases of the expected Bi2GeO5 and second phase Bi4Ge3O12 while Bi2GeO5 phase only observed in the glass ceramics prepared from Al2O3 crucible. Crystallinity and phases of the glass ceramics have a significant effect on their dielectric properties.
Photo-Induced Superhydrophilic TiO2 Films Deposited by DC Reactive Magnetron Sputtering at Room Temperature
Authors: Horprathum M. , Chindaudom P. , Patthanasettakul V. , Rotbuathong S. , Eiamchai P. , Limsuwan Pichet
Published: March 2009

Titanium dioxide (TiO2) thin films, 80-170 nm thick were deposited on unheated silicon wafers (100) and glass slides with controlled operating pressure in UHV dc sputtering system with a pressure control gate valve. The dependence of hydrophilic property of the films on the total sputtering pressure of mixed Ar and O2 gases (1-10 mTorr) was investigated. We found that hydrophilic activity as well as the structural and optical properties of the films were strongly related to the pressure maintained during the deposition. The TiO2 film structure and surface morphology were studied by X-ray diffraction (XRD), atomic force microscopy (AFM), field emission scanning electron microscopy (FE-SEM) and spectroscopic ellipsometry (SE). The optical constants of the TiO2 films was determined by SE. XRD showed that the films deposited between 1 – 5 mTorr had both anatase and rutile phase, but the rutile component reduced as the pressure increased. Only anatase peaks were obtained for the films deposited at pressure >5 mTorr. The AFM surface roughness decreased from 4.0 to 1.8 nm as the pressure increased from 1 – 10 mTorr. The contact angle measurement was used to determine the hydrophilicity of the films after exposed to UV light. I
Micro- and Macroscopic Observations of the Microtexture, the Dielectric and Piezoelectric Properties in Bulk and Multilayer Pb (Zr, Ti)O3
Authors: Binhayeeniyi N. , Dasaesamoh A. , Khakong J. , Khaenamkaew P. , Muensit S.
Published: March 2009

The objective of the present paper is to give an insight of the fundamental properties strongly depended on the crystallizing phase, grain size, thickness, including stoichiometry of material. The subject of this work is the lead zirconate titanate [Pb(Zr,Ti)O3, PZT] with its composition located at the morphotropic phase boundary (MPB) that were prepared by a solid state method [1] and a conventional sol-gel technique [2,3]. The samples prepared by the first methods are in a bulk form while the latter the multilayer. The physical property and the dielectric and piezoelectric properties of the PZT samples have been discussed comparatively when the sample size decreasing from the bulk to the thin-film scale.
High Capacity Packet Switching with a Soliton Pulse in a Nonlinear Micro Ring Resonator
Authors: Mitatha S. , Dejhan K. , Thongmee S. , Yupapin P. Preecha
Published: March 2009

We propose a new design of the secured packet switching using the nonlinear behaviors of soliton in a micro ring resonator, where the nonlinear penalty of light traveling in the device becomes benefit. The chaotic signals are generated by a Kerr effects nonlinear type of soliton in a micro ring resonator, where the control input power can be used to specify the output filtering signals. Some device parameters are chosen and simulated using the proposed model. Results obtained have shown in good agreement with the practical device behaviors. The potential of using such a device for communication security is performed and discussed. For instance, the packet switching of the chaotic encoding data increases from the chaotic signal encoding of 100 bit/s. Results obtained have shown the potential of using such a proposed device for the tunable band-pass and band-stop filters, in which the packet switching data can be performed and secured.
Temperature Dependent Photoluminescence of ZnSe/Alq3 Hybrid Heterostructure
Authors: Pecharapa Wisanu , Potirak P. , Yindeesuk W.
Published: March 2009

II-VI inorganic/organic heterostructures consisting of ZnSe and tris(8-hydroxyquinoline) aluminum (Alq3) were prepared by electron beam evaporator. Alq3 layer with 20 nm was grown between 200-nm ZnSe layers. Photoluminescence measurement was conducted at various temperatures in order to investigate the important temperature-dependent parameters of this structure. PL spectra revealed thermal population of exciton state and the change in PL quantum efficiency of the film.
Construction and Evaluation of the Fiber-Optic Sensor System for Chemical Vapor Detection
Authors: Kittidechachan M. , Sripichai I. , Supakum W. , Thuamthai S. , Angkaew Suppalak , Limsuwan Pichet
Published: March 2009

The fiber optic sensor system for chemical vapor detection was desiged and constructed. The system consisted of three parts; the optic unit, the fiber-optic sensing head and the flow controlling unit. The optic unit included a He-Ne laser source which lazes a red laser into an aligned optical fiber, a photo detector, and a signal processing with computer interface controlled by the Labview® program version 7.1. The sensing head was made of a polyaniline thin film coated onto the de-cladded section of an optical fiber covered by a gas mixing cell. The concentration of measured gas was controlled by varying nitrogen gas flow rate. The nitrogen flow controller was set-up to obtain vapor concentration in the range of 0.04 to 0.40 % v/v. Vapors of hydrochloric acid (HCl) and n-butyl amine (a weak base) were used to test the performance of the sensor system. It was found that output intensity increases with an increasing HCl concentration and decreases with increasing n-butyl amine concentration. The response toward the amine vapor was faster than that of the HCl vapor (23 seconds for n-butyl amine and 72 seconds for HCl). Experiments performed at various concentrations of amine vapor (between 0.04 to 0.21 %v/v) found that a higher concentration yields faster response time.
Improving Sensitivity of p-n Junction Temperature Sensor by Carrier Lifetime Modification
Authors: Poyai Amporn , Ratanaudomphisut E. , Supadech J. , Klunngien N. , Hruanan C. , Sophitpan S.
Published: March 2009

This paper presents the relation between the staring cobalt thickness with carrier generation lifetime, which effects to the sensitivity of p-n junction temperature sensor. The starting cobalt thickness of 12, 20 and 30nm have been used. The carrier generation lifetimes have been calculated from the reverse current-voltage (I-V) characteristics. The highest carrier generation lifetime has been obtained in the case of 12nm starting cobalt thickness. The highest sensitivity of p-n junction temperature sensor has also been observed from the case of 12nm starting cobalt thickness. The sensitivity has been calculated from the relation between leakage current versus temperature. The sensitivity of p-n junction temperature sensor can be improved by increasing carrier generation lifetime.
Finite Element Modeling of van der Waals Interaction for Elastic Stability of Multi-Walled Carbon Nanotubes
Authors: Thongyothee Chawis , Chucheepsakul Somchai
Published: March 2009

The purpose of this study is to assess the effect of van der Waals interactions within multi-walled carbon nanotubes with the three dimensional finite element models. The elastic buckling behaviors of nanotubes are treated under axial compressive force acting on open both ends of nanotubes and considered with various boundary conditions. The analysis is based on the assumptions that the covalent bond of each wall is represented by an elastic beam element while the van der Waals force of adjacent walls are represented by a nonlinear truss element following the Lennard-Jones “6-12” theory. The models of double-walled carbon nanotubes are used to explain the characteristic of multi-walled carbon nanotubes and then results compared with the column theory. The results show that the critical load of nanotubes depends on atomic arrangement, tube length, and number of walls, while the van der Waals force has a small effect on the buckling load for multi-walled carbon nanotubes.
Improvement of Mesopore Structure of Resorcinol and Formaldehyde Carbon Cryogels by Acid Solution
Authors: Kraiwattanawong K. , Kitchaiya P. , Neramittagapong Arthit , Praserthdam P. , Tamon H.
Published: March 2009

Resorcinol and formaldehyde (RF) carbon cryogels are prepared by sol-gel polycondensation by using sodium carbonate (C) as a catalyst with water (W) as solvent, immersed in acid solution, hydrochloric acid (HCl), dried by freeze-drying technique and then carbonized under inert atmosphere, respectively. Compared with their carbon precursors, both Vmes and mesopore size distributions of all carbon cryogels can be developed since the pore shrinkage is the crucial role in the change of pore structure of carbon gels. HCl may promote the strength of small pore structure and increase the pore shrinkage of large pore structure. Consequently, the treatment of HCl does not only enhance the partial collapse of large pore structure, the treatment also increases the strength of small pore structure to inhibit the shrinkage of this structure during carbonization as well.
Microstructure and Characterizations of Portland-Carbon Nanotubes Pastes
Authors: Nochaiya T. , Tolkidtikul P. , Singjai Pisith , Chaipanich Arnon
Published: March 2009

This research studied microstructure and characterizations of Portland cement with carbon nanotubes (CNTs) which were used as an additive material at 0 %, 0.5 % and 1 % by weight of cement. The compressive and flexural strength tests of mixes were conducted using water/cement ratios (w/c) of 0.5. Samples of mixes were selected for SEM analysis and then ground for TGA analysis. The results show that the compressive strength and flexural strength at all aging time of Portland-CNTs cement composites was higher than that of control mix. Microstructure results show that CNTs was filled in pores between matrix phases to show denser phase and TGA graphs show similar phases to PC mix.
Photocatalytic Decolorization of Red Dye in Aqueous ZnO-TiO2 Suspensions
Authors: Asl S.K. , Sadrnezhaad Sayed Khatiboleslam , Keyanpour-Rad M.
Published: March 2009

The photocatalytic decolorization of aqueous solutions of Direct Red 27 in the presence of various amounts of semiconductor powder suspensions has been investigated in a batch reactor with the use of artificial light sources. ZnO and TiO2 have been found the most active photocatalysts; the effect of catalyst loading and type on the reaction rate was optimized for maximum degradation. The results imply that 1:1 ratio is proper for the photocatalytic removal of Direct Red 27. In addition, the effects of particle size and surface area were examined in this photocatalytic process. The results showed that the decolorization efficiency increases with increase in surface area, and decrease in powder size. The efficiency is related to mechanism of reactions on the active sites of the catalyst surface and broad adsorption of compounds with different band gaps
Direct Synthesis of Anisotropic Metal Particles by Ink Jet Printing Technique
Authors: Kitsomboonloha Rungrot , Bera T. , Dutta Joydeep
Published: March 2009

Here we report the synthesis of nanoparticles with aspect ratios of up to five by synthesis in small concentrated volumes of reactants using an ink-jet printer. Silver and gold nanoparticles were synthesized rapidly on transparent sheets using a commercial ink jet printer. A commercial inkjet printer was modified by replacing conventional inks with different reactants including silver nitrate, ammonium-complex silver, gold chloride reduced by ascorbic acid. The reaction was allowed to occur directly on the substrate within a short reaction time and confined reaction volume defined by the droplet size on the substrate. The nanoparticles and microrods formed on the substrate depend on pH and ionic concentrations of the solutions. The pH of the solutions is an important factor controlling the aspect ratio of microrods. When the concentration of silver ions in the reactant solution was increased the number of particles deposited on the substrate increased subsequently. Anisotropic particles could be formed uniformly over very large area surfaces (1mm x 20mm). This method can be suitable for rapid synthesis of anisotropic particles for potential application in metal-enhanced fluorescence sensing, antibacterial coating, anti reflection coatings, amongst others.
The Effects of Substrate Temperature on Optical Properties and Surface Morphology of Nickel Phthalocyanine Thin Films Grown by Organic Evaporator System
Authors: Inchidjuy P. , Pukird Supakorn , Nukeaw J.
Published: March 2009

Thin films of Nickel Phthalocyanine (NiPc) are prepared at a base pressure of 10-6 mbar using Organic Evaporator System. The films are deposited onto the glass substrate at various temperatures of 100 0C, 120 0C, 140 0C and 160 0C. Crystalline of NiPc thin films was investigated by X-ray diffraction (XRD) spectroscopy. XRD patterns exhibit to become aggravated crystalline films as monoclinic structure. Surface morphology of NiPc thin films was characterized by field emission scanning electron microscope (FE-SEM). FE-SEM micrographs indicate that fiber-like morphology of NiPc is enhanced with increasing substrate temperature. The optical absorption spectra of these thin films are measured. Present studies reveal that the Q-band of NiPc thin films appears as the change of electron energy level. Absorption spectra obtained from UV-vis of deposited NiPc are declined as the substrate temperature is risen.
Mechanical Property Evaluation of ZnO Thin Films Using Nanoindentation and Scanning Probe Microscope
Authors: Fang Te Hua , Kang S.H.
Published: March 2009

The characteristics of morphology, friction and nanotribological properties of ZnO thin films were achieved by means of x-ray diffraction, scanning probe microscopy (SPM), and nanoindentation. The ZnO thin films were deposited by a radio frequency magnetron sputtering system. Surface geometry and friction analysis were derived from atomic force microscopy/friction force microscopy (AFM/FFM). The hardness and Young’s modulus of the ZnO thin films were investigated by nanoindentation measurements with a Berkovich indenter. The films exhibited an increase in the hardness with decreasing load i.e. the indentation size effect (ISE) was found. In addition, the nanoscratched mechanical property of the films was discussed.
Influences of Zr4+ and Polyacrylamide on Structural and Optical Properties of ZnO Nanoparticles Prepared via Microwave Irradiation
Authors: Pisitsak Penwisa , Magaraphan Rathanawan
Published: March 2009

The effects of polyacrylamide (PAM) as a capping agent, and zirconium as a dopant, on the structural and optical properties of ZnO nanoparticles were investigated. All the samples were prepared by microwave irradiation in an aqueous system without a post-annealing step. The crystallite sizes were decreased by the incorporation of Zr and PAM. The photoluminescence efficiency was enhanced for samples with PAM-capped ZnO and PAM-capped ZnO doped with Zr, when compared to the pure ZnO. The broad visible luminescence signified the suitability of these nanoparticles as a white phosphor.
Functionalized Porous Clay Heterostructure for Heavy Metal Adsorption from Wastewater
Authors: Tassanapayak R. , Magaraphan Rathanawan , Manuspiya H.
Published: March 2009

A wide variety of toxic metals and organic chemicals are discharged to the environment as industrial or laboratory wastes, causing serious water, air, and soil pollution. One of the interesting materials for using as the adsorbents to adsorb these pollutants in wastewater treatment is porous clay heterostructures (PCHs). These porous materials are obtained by the surfactant-directed assembly of mesostructured silica within clay layers. In the present work, the PCHs were synthesized within the galleries of Na-bentonite clay by the polymerization of tetraethoxysilane (TEOS) in surfactant templates (cetyltrimethylammonium ion and dodecylamine). These PCHs were functionalized with 3-mercaptopropyltrimethoxysilane (MPTMS) to obtain the MP-PCH utilizing as heavy metal adsorbent. According to N2 adsorption-desorption data, the results show that PCH has surface areas of 549.7 m2/g, an average pore diameter in the supermicropore to small mesopore range of 3.16 nm, and a pore volume of 0.45 cc/g, while MP-PCH shows pore parameters of 488.7 m2/g, 3.28 nm, and 0.48 cc/g, respectively. Moreover, the MP-PCH was investigated the adsorption properties which concerned with their function as adsorbents for aqueous solution. The results show that the adsorption capacity of MP-PCH was 0.22, 0.24, 0.50 , 0.48 and 0.11 mmol/g for Cd, Cu, Mn, Ni and Pb, respectively. They point out the potential for utilizing as the heavy metal adsorbents in wastewater treatment.
Improvement of Hydrophobic Properties of the Electrospun PVA Fabrics by SF6 Plasma Treatment
Authors: Thongphud A. , Paosawatyanyong Boonchoat , Visal-athaphand P. , Supaphol Pitt
Published: March 2009

Electrospun fabrics, prepared from 5, 7 and 10%w/v were Poly(vinyl alcohol) (PVA) solutions successfully prepared. The electrospinning condition was 15 kV, distance 15 cm, flow rate of 1 ml/hr and spinning time of 5 hours. Physical properties of electrospun PVA fabrics were analysed by SEM, FE-SEM and contact angle measurement.The contact angle of the electrospun PVA fabrics was 54.5°, characterizing the hydrophilicity of the fabrics. Hydrophobic properties of the electrospun PVA fabrics were improved by plasma treatment using radio frequency inductively coupled plasma (RF-ICP). RF-ICP plasma treatment of the electrospun PVA fabrics were carried out sulphurhexafluorene (SF6) gas with pressure of 0.5 Torr, RF power of 30W and treating time of 30, 60, 90 and 120 seconds. Effects of the PVA solution concentration and plasma treating time on hydrophobicity of the electrospun PVA fabrics were determined by contact angle that result of contact angle of treated fabrics increased when treated time increased and they decreased when concentration of fabrics increased.
Synthesis of SiO2 Nanopowder from Rice Husk Ash
Authors: Ruksudjarit A. , Rujijanagul Gobwute
Published: March 2009

In the present work, we demonstrate a method to synthesis SiO2 nanopowder from rice husk ash by using a vibro-milling followed by a heat treatment technique. Rice husk ash was milled by vibro-milling for 4 h to obtain nanopowder. In order to eliminate carbonaceous material, the nanopowder was heat at 1000°C for 3 h. Characteristic of the powder was then investigated by XRF, XRD, and SEM techniques. The silica nanopowder with 95% purity was obtained after the heat-treatment. The result indicated that the present method is a beneficial process to produce the silica nanopowders of low cost and high mass productivity.
Time-of-Flight Measurement of Poly(3-Hexylthiophene) Thin Films
Authors: Sittishoktram M. , Asawapirom Udom , Osotchan Tanakorn
Published: March 2009

Poly(3-hexylthiophene) (P3HT) is one of the most studied conjugated polymer for molecular electronics especially for organic field effect transistors (OFETs) and organic light-emitting devices (OLEDs). This is mainly due to the fact that P3HT provides excellent electrical properties and showed high carrier mobility. In this research we studied the photo generated charge carrier transport of P3HT film by the time-of-flight (TOF) method. For device fabrication, P3HT was dissolved in chloroform with concentration of 8 mg/ml then the solution was spun directly onto an ITO pattern coated on glass substrate. Then the aluminum electrode was prepared on film by thermal evaporation. In TOF measurement, the constant voltage was applied to electrode of sample and the film were photo-excited by irradiation of a short pulsed laser light (λ=650 nm). This caused charge separation within the film. The generated charge carrier was used to calculate the mobility of the film. The TOF mobility was determined as a function of applied voltage and light condition.
Design and Preparation of a Bioresponsive Hydrogel for Biomedical Application as a Wound Dressing
Authors: Witthayaprapakorn C. , Molloy Robert , Nalampang K. , Tighe B.J.
Published: March 2009

In this work, the sodium salt of 2-acrylamido-2-methylpropanesulfonic acid (Na-AMPS) was photopolymerised in aqueous solution with ethylene glycol dimethacrylate (EGDM) added as a crosslinking agent and 4,4'-azo-bis(4-cyanopentanoic acid) as the water-soluble photoinitiator. The aqueous solution was poured into a vertical sheet-forming mould consisting of two parallel plates covered with Teflon® sheets as release liners. Spacers were used to control the sheet thickness with a polymer mesh inserted in the middle to strengthen the hydrogel. The hydrogel sheets obtained were of 1.2 ± 0.2 mm thickness and showed good transparency, flexibility and skin adhesion. On immersion in distilled water at 37°C, it was found that the equilibrium water content (EWC) reached 98 ± 1% within 20 mins following which the equilibrium water retention (EWR) in ambient air was 21 ± 1% over a period of about 4 hrs. The water vapour transmission rate (WVTR) was measured at 37 °C and was found to be 82 ± 2 g m-2 hr-1. It is concluded that this Na-AMPS hydrogel sheet has properties which show potential for biomedical use as a wound dressing.
Dielectric and Piezoelectric Properties of B2O3 and SnO2 Doped Barium Titanate Ceramics
Authors: Tawichai Nattaya , Rujijanagul Gobwute
Published: March 2009

Boron oxide doped barium stannate titanate ceramics were prepared by a solid-state reaction method. Properties of the ceramics were investigated. The experimental results showed that most properties of the ceramics depend on the sintering temperature. The higher relative permittivity of 13887 with tan 0.034 at 34 °C was observed for the samples sintered at 1350 C. Piezoelectric coefficient (d33) of the samples was found to be in the range of 90 - 115 pC/N. However, the optimum d33 coefficient was observed for the sample sintered at 1250 C.
Development of a Protein-Filled Conduit for Peripheral Nerve Regeneration
Authors: Yingsukwattana K. , Agthong S. , Mongkonnavin R. , Tabata Yasuhiko , Kanokpanont Sorada
Published: March 2009

Currently, most commercialized peripheral nerve regenerative products are constructed from biodegradable polymers into hollow conduits. To speed up the regeneration rate, we proposed a development of a biocompatible protein-filled conduit for anastomosis amputated peripheral nerve with growth factor controlled release function. Glutaraldehyde-crosslinked protein sponges were tested for their abilities to controlled release of nerve growth factor (NGF) in vitro in our previous experiments. Type B gelatin sponges were able to limit diffusions of NGF due to electrostatic interactions between them. The rate of growth factor releases would be depended on degradation of the crosslinked gelatin. A nerve conduit model was produced using perfluoro alkoxy (PFA) tubes filled with gelatin which had been crosslinked using X-ray from Argon plasma treatment. This method of crosslinking provided 21.22±3.03 % degree of crosslinking. Hollow nerve conduits fabricated from poly(l-lactide-co-caprolactone) (PLCL) had a thicknesses and an inner diameters of 0.31±0.03 mm and 1.63±0.07 mm respectively. Average pore sizes of the inner surfaces and outer surfaces were 9.70±3.44 µm and 1.24±0.77 µm respectively. PLCL film supported growth of L929 mouse fibroblasts. For continuing works, we are testing the protein-filled conduits for peripheral nerve regeneration in animals.
Ultrastructural Characterization of Liposomes Using Transmission Electron Microscope
Authors: Chetanachan Prukswan , Akarachalanon P. , Worawirunwong D. , Dararutana Pisutti , Bangtrakulnonth A. , Bunjop M. , Kongmuang S.
Published: March 2009

A liposome is a spherical vesicle composed of phospholipids and cholesterol bilayer membrane and contains a core of aqueous solution. Liposomes are polymeric nanoparticles used for drug delivery due to their unique properties. It can carry both hydrophobic and hydrophilic molecules. In this study, we showed the benefit of using transmission electron microscope (TEM) with negative staining technique to investigate the morphology of liposomes produced by thin film method. At the same magnification of micrograph results, we could see the multilamellar vesicles of liposomes in various figures and different sizes.
Study on Morphology and Thermal Stability of Nanoporous Silk Fibroin Films
Authors: Srisuwan Y. , Kotsaeng N. , Baimark Y. , Narkkong N. , Simchuer W.
Published: March 2009

Nanoporous silk fibroin (SF) films were prepared as SF film loaded with methoxy poly(ethylene glycol)-b-poly(D,L-lactide) (MPEG-b-PDLL) nanoparticles by film casting of MPEG-b-PDLL nanoparticle suspension-SF solution. Nanoporous structures of the SF films were formed due to self-condensation and nanophase separation of nanoparticles from SF film matrix during drying process. The films with SF/MPEG-b-PDLL ratios of 20/1, 20/2 and 20/3 (w/w) were prepared and investigated. The MPEG-b-PDLL nanoparticles can be observed on film surface and cross-section with 100-300 nm in size. The size of interconnected nanopore was in the range of 20 – 300 nm. The number and size of nanopores increased as increasing the MPEG-b-PDLL ratio. Thermal stability of the films studied from differential thermogravimetric (DTG) thermogram found that the nanoparticles dispersed into the SF films could improve thermal stability of each component. This indicated strong hydrogen bond interactions between SF and MPEG-b-PDLL were existed. Film transparency of the SF nanoporous films decreased when the MPEG-b-PDLL ratio was increased.
Ferroelectricity of (1-x)(Bi0.5Na0.5)TiO3 – xBa(Ti0.95Zr0.05)O3 Solid Solution Ceramics
Authors: Sawangwan N. , Tontrakoon J. , Sirisoonthorn S. , Tunkasiri Tawee
Published: March 2009

(1-x)(Bi0.5Na0.5TiO3)-xBa(Ti0.95Zr0.05)O3 ceramics were prepared by the mixed oxide technique and their dielectric, piezoelectric and ferroelectric properties determined in detail in the range x = 0.06 to 0.09. At x = 0.07 the maximum relative permittivity of 1338 and piezoelectric constant of 167 pC/N were obtained. It was concluded that 0.93(Bi0.5Na0.5TiO3)-0.07Ba(Ti0.95Zr0.05)O3 is the morphotropic phase boundary region for this system.
Novel Three-Component Blends Based on Poly(L-Lactide)
Authors: Juikham S. , Amass A.J. , Tighe B.J.
Published: March 2009

A significant number of poly a-ester homologues of poly(L-lactide) (PLLA) have been synthesized and used in miscibility studies together with conventional isomeric diacid-diol polyester variants, poly β-esters (based on β-hydroxybutyrate (HB) and β-hydroxyvalerate (HV)), poly e-caprolactone (PCL), poly e-caprolactone copolymers (e.g. poly(L-lactide-co-caprolactone), and a series of cellulose-based polymers (e.g. cellulose acetate butyrate (CAB), cellulose acetate propionate (CAP)). A combinatorial approach to rapid miscibility screening using 96-well plates and a uv-visible multi-wavelength plate reader has been developed enabling the clarity of PLLA-based multi-component blend films to be observed. Using these techniques and materials, the ternary phase compatibility diagrams of a range of three-component blend films was prepared, illustrating ranges of behavior varying from miscible blends giving rise to clear films to immiscible blends which are opaque. In this way, novel three-component blends of PLLA/CAB/PCL were developed which are miscible when the CAB content is more than 30%, PLLA less than 80% and PCL less than 60%.
Synthesis and Characterization of PLA-Based Aliphatic-Aromatic Copolyesters: Effect of Diols
Authors: Namkajorn M. , Petchsuk Atitsa , Opaprakasit Mantana , Opaprakasit Pakorn
Published: March 2009

PLA-based aliphatic aromatic copolyesters have been synthesized and characterized in order to incorporate the degradability of PLA and good mechanical properties of aromatic species. Synthesis of the copolymers was conducted by polycondensation of lactic acid with dimethyl terephthalate (DMT) and various diols using stannous(II) octoate as a catalyst. Three types of diols with different methylene lengths were employed, i.e., ethylene glycol (EG), propylene glycol (PG) and 1, 4-butanediol (BD). Effects of diols and comonomer molar ratio on the extent of polycondensation reaction and molecular weight of the resulting copolymers were investigated. Diacids and diol ratios of L-lactic acid (LLA), dimethyl terephthalate (DMT) and diol of 1/1/2, 1/2/4 and 2/1/2 were employed. Characterization of chemical structure, molecular weight and thermal and physical properties of the resulting copolymers were conducted by FTIR, NMR, and DSC.
Preparation of IR Reflective Green Pigment
Authors: Thongkanluang Thadsanee , Limsuwan Pichet , Rakkwamsuk P.
Published: March 2009

This research article reports a development on green pigments having high reflectance of NIR radiation from the sun. The aim of the development is to use the green pigments as a component of building paint to reduce heat penetrating into the building. Cr2O3, a green pigment oxide, was used as the host component and the mixtures of Al2O3, V2O5 and TiO2 were used as the guest components. Al2O3, V2O5 and TiO2 were mixed at different 36 compositions according to triaxial diagram. For each sample preparation, 80% wt Cr2O3 was mixed with 20%wt of guest component for each composition. Then the mixed sample were calcined at 1150 °C for 4 hours and were ground with an agate ball mill for 7 minutes at a speed of 250 rev/min. Finally, the pigments were sieved to obtain the particle sizes of 0.5 - 2.0 µm. The pigment powders were compressed in a mold to get samples in the form of thin disks, each one with a diameter of 2.7 cm and a thickness of 4 mm. The reflectance for all samples was measured using a spectrophotometer in the wavelength ranging from 300 – 2100 nm in accordance with ASTM E891. It was found that the maximum reflectance, in the wavelengths ranging from 780 – 2100 nm, of 82.83% was obtained from the sample with a composition of 80%Cr2O3, 14%Al2O3, 4%TiO2 and 2% V2O5.
Thermoelectric Properties of BixSbyTezSew Nanocomposite Materials
Authors: Kosalathip V. , Kumpeerapun T. , Migot S. , Lenoir B. , Dauscher A.
Published: March 2009

Nanopowders of n-type (Bi0.95Sb0.05)2(Te0.95Se0.05)3 and p-type (Bi0.2Sb0.8)2Te3 have been synthesized by laser fracture of micron-sized powders in water. These alloys are the best conventional thermoelectric materials for use in room temperature applications. The nanopowders have been characterized by x-ray diffraction, scanning electron microscopy, and transmission electron microscopy. The nanopowders have been mechanically mixed in different ratios with the micron sized powders. These mixtures have then been cold pressed in order to perform thermoelectric characterization and to see the influence of nano-particle inclusions on the transport properties.