bluuebunny/crossref_metadata_2025 huggingface dataset:
Preparation and Applications of Precious Metals Adsorbed Activated Carbon Cloth
Authors: Saipanya Surin , Sarakonsri Thapanee
Published: January 2010

Precious metal nanoparticles (e.g. Au, Pd and Pt) on activated carbon cloths (ACCs) were simply prepared by impregnation of metal salts dissolving in ethanol solution. Pretreatment of the ACCs was firstly performed in hydrochloric acid solution and nitric acid as oxidizing agent was employed in order to introduce oxygen complex on the ACCs fiber surfaces. Uniformly dispersed metal nanoparticles with diameter of 5-20 nm on the ACC surfaces were simply achieved without using reducing agents. Morphology and composition of the metal adsorbed ACCs were examined by Scanning Electron Microscopy (SEM) and Energy Dispersive Spectroscopy (EDS), respectively. Electrolytic activity of metal/ACCs was investigated by using cyclic voltammetry (CV) to demonstrate the electron-transfer properties. Results demonstrate that metals adsorbed ACCs were easily prepared with simple procedures which will be more convenient for preparations and applications.
Alteration of Thermal Characteristics of Polymer for the Purpose of Creating a Two-Stage Shape Memory Polymer
Authors: Tamagawa Hirohisa
Published: January 2010

A polymer fabricated by mixing PU soft segment and epoxy bore the thermal characteristics of the melting temperature, Tm, of PU soft segment and the glass transition temperature, Tg, of epoxy. The polymer fabricated even exhibited the shape memory effect at the Tg and Tm. Based on this observation, it was speculated that simply mixing two polymers bearing totally different thermal characteristics each other could result in a two-stage SMP, which could exhibit the shape memory effect at the two distinct temperatures. However, it was actually observed that the two-stage SMP was not always successfully created by that method. But DSC measurements revealed that such an unsuccessfully fabricated SMP still bore the thermal characteristics of its ingredient polymers. Hence, the mixing of appropriate polymers still could result in a new two-stage SMP, and the method of two-polymer-mixing must be still an effective method for creating a two-stage SMP.
Composite Polymer Electrolyte for Dye-Sensitized Solar Cells: Role of Multi-Walled Carbon Nanotubes
Authors: Chindaduang A. , Duangkaew Pattasuda , Pratontep Sirapat , Tumcharern Gamolwan
Published: January 2010

We focus on the energy conversion improvement of dye-sensitized solar cells by using poly(ethylene oxide)-multi-walled carbon nanotube (PEO-MWCNT) electrolyte. Compared with the MWCNT-free solar cells, the addition of 0.05 wt.% MWCNTs in the polymer electrolyte results in a dramatic increase of the short-circuit current (Jsc), consequently raising the device performance by approximately 9% under a direct light of the Air Mass 1.5 irradiation at 100 mW cm-2. The role of the conductive carbon materials in the polymer electrolyte have been investigated by means of ionic conductometry, electrochemical impedance spectroscopy and UV-visible spectroscopy. This work demonstrates that MWCNT additives in polymer electrolytes is a convenient yet effective strategy for improving the performance of photovoltaic devices.
Preparation and Characterization of Heparin-Retinoic Acid-Folic Acid Conjugates for Targeted Cancer Therapy
Authors: Park Il Kyu , Kim Yu Jin , Huh Kang Moo , Lee Yong Kyu
Published: January 2010

To make significant progress in the fight against cancer, treatment should target cells more specifically, produce fewer side effects, be easy to administer and deter tumor viability on multiple levels. We have attained dramatic in vivo tumor shrinkage and tumor vasculature disruption using a ternary biomolecular nanoparticle comprised of polymeric carrier polysaccharide heparin, anticancer drug retinoid and targeting ligand folic acid. The conjugation of retinoid and folic acid to heparin enhanced the water solubility of the drug, enabled selective targeting, and enhanced the role of heparin as anti-cancer drug carrier by eluding the coagulation cascade. This approach for targeting tumor holds great promise for treatment of various types of cancer. The folic acid linked heparin-retinoid conjugates (HFR) reactions was conjugated with ester and amide bonding which was confirmed by fourier transform infrared (FT-IR) and proton nuclear magnetic resonance (1H-NMR). The ratio of HFR conjugates was measured with Ultra-Violet spectrometry (UV-spectrometry). The particle size of HFR nanoparticles was measured by dynamic light scattering (DLS), and transmission electron microscopy (TEM). HFR conjugates were spherical and showed a diameter range of 200-300 nm in size. The nanoparticles maintained their stability in serum condition for 48hrs and have the high potential for applications in biomedical field.
Preparation and Properties of Natural Rubber - Cellulose Microfibril Nanocomposite Films
Authors: Phiriyawirut M. , Chotirat Natnapa , Phromsiri Sirikul , Lohapaisarn Ingorn
Published: January 2010

The property of cellulose microfibril reinforced natural rubber film was studied. Cellulose microfibril was prepared from banana powder (300 µm). The interconnected structure of cellulose microfibril having a diameter of 27 nm was observed by TEM. The effect of cellulose microfibril content (0.8-3.2 % wt) in the property of NR nanocomposite film was studied. Tear strength and thermal properties of the NR nanocomposite film is improved by increasing the cellulose microfibril content. Moreover, water absorption of the nanocomposite film is increased by increasing cellulose microfibril content. Increasing of cellulose microfibril content also enhances water permeation of nanocomposite films.
Ameliorating Soil Sodicity Using Calcium Salt Incorporated Hydrogels
Authors: Ng Loo Teck , Aiken Jane
Published: January 2010

The potential of using hydrogels encapsulated with a water-soluble calcium salt, Ca(NO3)2 for the remediation and management of sodic soil, a degenerate soil condition associated with irrigation of recycled water was investigated. Environmentally friendly hydrogel, poly(2-hydroxyethyl methacrylate) (PHEMA) was synthesised from the monomer, 2-hydroxyethyl methacrylate (HEMA). HEMA was also used to copolymerise with another monomer, N-vinyl pyrrolidinone (NVP) to form a more hydrophlic hydrogel. Starch and glucose were incorporated in certain hydrogels with the intention of evaluating their biodegradability in soils since starch and glucose would serve as nutrients for microbials in soils. Delivery of calcium ions embedded in hydrogels were investigated on sodic and non-sodic clay loam under saturated condition. It was found that the optimum hydrogel for this application was the copolymer that contained HEMA and NVP in equal mole ratio.
Microwave-Assisted Modification of Arrowroot Starch for Pharmaceutical Matrix Tablets
Authors: Sriamornsak Pornsak , Juttulapa Maneerat , Piriyaprasarth Suchada
Published: January 2010

As a new processing method for the production of modified starch, microwave heating was applied to native arrowroot starch. The effect of processing parameter on the sustained release properties of the obtained modified starches was investigated. The modified starch was blended with a model drug, theophylline, and then compressed into tablet using hydraulic press at a pressure of 19.6 kN for 30 s. The physical properties as well as drug release behavior of the compressed tablets were investigated. The results showed that the physical properties of different modified starches were about the same. The modified arrowroot starch displayed better sustained release properties than native starch. The modified arrowroot starch, which subjected to microwave heating using high level of water content, long heating time and high microwave power, demonstrated promising properties as hydrophilic matrix excipients for sustained release tablets.
Surface Modification of Silica Nanoparticles for Reinforcement of Epoxidized Natural Rubber
Authors: Jarnthong Methakarn , Peng Zheng , Nakason Charoen , Lopattananon Natinee
Published: January 2010

Epoxidized natural rubber (ENR) based nanocomposites were prepared by mixing ENR latex (epoxide content of 35 mole%) with silica nanoparticles (SiO2). SiO2 were previously treated with 3-aminopropyltriethoxysilane (APS) and 3-methacryloxypropyltrimethoxysilane (MPS). Morphological and mechanical properties of ENR/SiO2 composites were investigated. The dispersion of SiO2 in ENR matrix, which was characterized by SEM, indicated that the treated SiO2 exhibited better dispersion than that of the untreated SiO2. Moreover, it has been found that the modified SiO2 with either APS or MPS gave much significant reinforcing effect than the untreated one. However, the treatment of SiO2 nanoparticles with MPS resulted in better interfacial interaction when the APS treatment was compared.
Effect of Thai Silk Sericin and its Extraction Methods on L929 Mouse Fibroblast Cell Viability
Authors: Thitiwuthikiat Piyanut , Aramwit Pornanong , Kanokpanont Sorada
Published: January 2010

Sericin, one of the two main proteins of silk cocoon besides fibroin, has been wildly used as ingredient in cosmetic products and nutrition supplements; however there are considerable controversial reports on its toxicity to cells and its advantages. This work aimed to investigate cell biocompatibility of sericin both in the systems of blended silk fibroin/sericin and pure sericin films using L929 mouse fibroblasts. The effect of concentration of commercial heat extracted sericin on cell viability was first investigated in the system of silk fibroin/sericin (F/S) films using 2 types of silk fibroin, Bombyx mori Nangnoi Srisaket 1 and Bombyx mori Jul 1/1. For both types of silk fibroin, it was found the lower cell number attached and proliferated on the blended F/S films at all sericin concentrations, compared to that on glass and pure fibroin. However, proliferation rate of cells cultured on the blended F/S films was similar to that of cells cultured on glass and pure fibroin films, as confirmed by population doubling time (PDT). Cytotoxicity of sericin extracted from 4 different methods including heat, acid, alkali and urea treatments was further studied in this work in the system of pure sericin films. It could be seen that acid and urea extracted sericin films showed high percentage of cell attachment at 92% and 88%, respectively. However, number of cells proliferated on all sericin films after 48 h culture was not significantly different. This indicated that L929 cells had different proliferation rate when cultured on different types of sericin films. Among 4 extraction methods, the PDT of cells proliferated on urea extracted sericin film was lowest (27 h) and also lower than that of the blended F/S films. This study suggested that sericin extracted by urea treatment could enhance proliferation rate of L929 mouse fibroblasts.
Graft Copolymerization of Methyl Methacrylate onto Natural Rubber by Microwave Irradiation
Authors: Piyaauksornsak Sirichai , Paosawatyanyong Boonchoat , Hinchiranan Napida
Published: January 2010

The graft copolymerization is one chemical modification methods to improve natural rubber (NR)’s properties via both solution and latex phases. To enhance the polarity of NR, methyl methacrylate (MMA) was applied for graft copolymerization of NR in the presence of thermal or redox initiators. However, the conventional graft copolymerization generally spends long reaction time (ca. 6-8 h). Due to less energy consumption with faster heating rate, the microwave irradiation was used to induce graft copolmerization of MMA onto NR latex using redox initiation system. By comparing with the conventional grafting method at the same grafting properties, the graft copolymerization of MMA onto NR induced by microwave at 100 W spent the shorter reaction time ca. 15 min; whilst, the conventional method required the longer reaction time as 7 h. The influence of microwave power on the grafting properties was investigated. The structure of graft product was also analyzed by using FTIR and 1H NMR spectroscopy.
Spray-Dried Pectic Polysaccharide Powders: Evaluation of Physicochemical Properties for Pharmaceutical Preparations
Authors: Nutithawat Thanyamas , Kusonwiriyawong Chulalongkorn , Ritthidej Garnpimol C.
Published: January 2010

Pectic polysaccharide from durian rinds (Durio Zibethinus) has been reported to mainly compose of pectin which is generally used in various pharmaceutical dosage forms. The purpose of this research was to investigate the physicochemical properties of spray-dried pectic polysaccharide powders as a function of spray drying conditions (inlet temperature, feed rate, and aspirator rate) and formulation parameters (pectic polysaccharide concentration). A mini spray dryer was used to spray dry pectic polysaccharide in formulation with maltodextrin, colloidal silica and propylene glycol. Production yields were obtained between 31.08 – 52.87%. Higher yield percentage was obtained when the inlet temperature was increased. Particle size of < 7m was from low pectic polysaccharide concentration. The pectic polysaccharide powders were bulky and the shape was almost spherical with smooth surface but collapsed at high inlet temperature and low feed rate. At 75% RH and room temperature, the powders could adsorb moisture of about 12% of the powder weight. The swelling index and mucoadhesion time that the powders attached to the porcine intestine was ranged 14 – 70 and 7 - >30 minutes, respectively. This research provides useful information for development of pectic polysaccharide as fine powder for drug delivery.
Applications of Non-Linear Dynamics in the Production of Functionalised and Sensing Material
Authors: Subasinghe Nalaka Deepal
Published: January 2010

Certain applications of functionalised and sensing material require network of connectors such as conducting nano-wires, to pick displaced electrons or signals from an external source. Making nano-scale networks of connections that are durable, efficient and continuous is always a challenge for the material scientists. A possibility to achieve the above goals by mimicking dendritic and other diffusion patterns in nature is discussed here. These ‘naturally grown’ textures have the following characteristics that are very useful, as their intrinsic properties: 1. two branches will never overlap (saving material and avoiding any short circuiting), 2. all the branches will always have in contact with the root. Further, when it is practically impossible to develop a network of branches in an already existing solid material, induced dendritic growth using controlled diffusion can be used to do the job.
Characterization of PVDF-HFP-LiCF3SO3-ZrO2 Nanocomposite Polymer Electrolyte Systems
Authors: Ibrahim Salmiah , Hashim Ali Siti Aishah , Nor Sabirin Mohamed
Published: January 2010

Nanocomposite polymer electrolytes were prepared by incorporating different amounts of zirconium oxide (ZrO2) nanofiller to poly(vinylidene fluoride-co-hexafluoropropylene)-lithium trifluoromethane sulfonate (PVDF-HFP-LiCF3SO3). X-ray diffraction (XRD) study has been carried out to investigate the structural features of the electrolyte films while a.c. impedance spectroscopy has been performed to investigate their electrical properties. The conductivity of nanocomposite polymer electrolyte systems is influenced by nanofiller concentration. The increase in conductivity is attributable to the increase in the fraction of amorphous region and the number of charge carriers and vice versa. The highest conductivity obtained is in the order of 10-3 S cm-1 for the system dispersed with 5 wt% of ZrO2 nanofiller.
Properties of La2-xSrxMo2-yWyO9-δ Oxide-Ion Conductor Synthesized by Citrate Gel Method
Authors: Thepsuwan Witoon , Kuharuangrong Sutin
Published: January 2010

Properties of La2-xSrxMo2-yWyO9-δ (x = 0-0.2, y = 0-0.3) synthesized via citrate gel method have been investigated on phase, oxidation state, microstructure and electrical conductivity. The XRD results show a single phase after calcination at 700 oC for all compositions. The oxidation state of Mo in La2-xSrxMo2-yWyO9-δ compositions determined by X-ray Absorption Near Edge Structure (XANES) is found to be +6. The average grain size of sintered compositions increases with the amount of Sr but slightly decreases with an addition of W. At 500 oC, all doped compositions exhibit higher conductivity as compared to 5.42×10-4 S∙cm-1 for undoped-La2Mo2O9. In this work, the composition of La1.9Sr0.1Mo2O9-δ performs the highest conductivity value of 1.95×10-3 S∙cm-1.
TiOx Concentration Dependence of OPV Efficiency Optimization
Authors: Keawprajak Anusit , Piyakulawat Phimwipha , Wlosnewski Joerg , Iamraksa Phansak , Saekung Chaiyuth , Asawapirom Udom
Published: January 2010

Titanium oxide TiOx material is used as electron transporter in organic photovoltaic cells (OPV). The layer was prepared between P3HT:PCBM as the active layer and the and aluminum electrode by spin coating technique. The synthesis and characterization of TiOx is described. Using Raman spectroscopy technique TiOx crystals show anatase structure. Varied concentrations of TiOx and isopropanol solvent were performed. The most optimized device efficiencies up to 2,0% was achieved at a 1:20 ratio, which indicated more than 50% efficiency enhancement comparing with the device without TiOx layer. The major improvement of the cell was originated from photocurrent enhancement.
Preparation of Highly Monodisperse Polymeric Particles Incorporating Polymerizable Perylene-Bisimide Fluorophore
Authors: Piyakulawat Phimwipha , Polpanich Duangporn , Thiramanas Raweewan , Asawapirom Udom
Published: January 2010

In this work, the yellow emitted perylene-bisimide dye with polymerizable functional groups was synthesized by condensation reaction of perylene tetracarboxylic acid dianhydride and allyl amine. The resulting polymerizable fluorophore was characterized in terms of structure with NMR and FT-IR, the absorption and emission properties by using UV-Vis and fluorescence spectroscopy, respectively. Afterwards, the reactive polymerizable fluorophore was incorporated into the polymer nanoparticle by copolymerization with styrene and acrylic acid monomers via miniemulsion polymerization. The obtained fluorescent nanoparticles was stable and showed a highly monodisperse size distribution with hydrodynamic diameter of 91.8±0.4 nm.
Compositional Changes of Enamel and Dentine after Er:YAG Laser Irradiation
Authors: Choeysuppaket Attapol , Pokaipisit Artorn , Limsuwan Pichet
Published: January 2010

The aim of the present study was to investigate the organic and inorganic compositions of enamel and dentine after Er:YAG laser irradiation using Fourier-transform Raman spectroscopy (FT-Raman). The enamel and dentine of extracted human teeth were irradiated by Er:YAG laser at an energy density of 29.7 J/cm2. The organic and inorganic components were evaluated from Raman spectra of untreated and laser-treated of extracted human teeth. The results showed that the Raman intensity ratio of the carbonate peak (1067 cm-1) to the phosphate peak (957 cm-1) and the organic peak (2940 cm-1) to the phosphate peak of enamel and dentine decreased after laser irradiation. Therefore, laser treatment can reduce the organic and inorganic components of human enamel and dentine.
Property Modification of Copper Phthalocyanine Film by Nitrogen Dioxide Gas
Authors: Jaisutti Rawat , Theerasak Juagwon , Chamlek Onanong , Osotchan Tanakorn
Published: January 2010

Copper Phthalocyanine (CuPc) thin films have a potential to use as nitrogen dioxide (NO2) gas sensor therefore the study of property modification of CuPc thin film by NO2 gas can lead to a better understanding the sensor operation. CuPc thin films were prepared by thermal vacuum deposition on glass substrate and aluminum interdigitated electrodes. The film characteristics were investigated with and without NO2 gas. These characteristics indicated that the resistance of CuPc film decrease as the NO2 concentration increases. In order to achieve high efficient of sensing properties, the post-deposition film was also annealed. The surface modifications were investigated with different exposed time of NO2 gas. Their properties modifications before and after annealing were investigated on the film morphology and crystalline structure. The surface morphology of the film was examined by atomic force microscopy while the crystalline structure of the film was determined by x-ray diffraction. The electrical measurements of CuPc film exposed to NO2 gas were studied in order to investigate property modification of the CuPc film.
Nanocrystal-ZnO Thin Film Deposition by a Novel Reactive Gas-Timing RF Magnetron Sputtering Provided for UV Photodetectors
Authors: Panprom P. , Porntheeraphat S. , Bunjongpru Win , Tiwawong T. , Yamwong W. , Hruanun C. , Poyai Amporn , Nukeaw J.
Published: January 2010

The fabrication and characterizations of nanocrystal-ZnO thin film used as active layer of MSM-photodetector structure are reported. The ZnO thin film were successfully sputtered on SiO2/Si substrates without heating or annealing processes by using a novel reactive gas-timing technique. In our experiment, the ZnO thin film properties with different gas-timing ratio of Ar/O2 were investigated. For fabricating of UV detector, the Al interdigitate electrode was deposited on SiO2/Si substrate by DC sputtering process and ZnO thin film was deposited as active layer. The response wavelength peak occurs at around 380 nm corresponding to ZnO energy bandgap of 3.2 eV .The I-V measurements indicates the Schottky behavior of ZnO on Al contact.
CoPc/CdS Hybrid Photovoltaic Device
Authors: Keeratithivakorn P. , Tunhoo B. , Thiwawong T. , Nukeaw J.
Published: January 2010

The organic-inorganic hybrid photovoltaic (PV) cells based on cadmium sulphide (CdS) and cobalt phthalocyanine (CoPc) films have been fabricated and characterized their PV performance. This investigated the effects of the organic and inorganic layer thickness on the photovoltaic properties, these thickness was controlled at various values such as 10, 30 and 50 nm. However, the performance of the hybrid photovoltaic cells was depending on the organic layer thickness. The optimize results of PV cell with CoPc 10 nm and CdS 30 nm showed an open-circuit voltage (Voc) = 0.536 V, a short-circuit current density (Jsc) = 0.1020 mA/cm2, a fill factor FF = 0.281 and a power conversion efficiency (η) = 0.01536 % under the AM1.5 conditions. Efficiency is enhanced by 22 times with the addition of a buffer layer, bathocuproine (BCP) 5 nm, the power conversion efficiency (η) value from 0.01536 to 0.34571%.
The Optimization of TiN Film Deposited by DC Magnetron Sputtering Provided for Al Diffusion Barrier
Authors: Pankiew A. , Bunjongpru Win , Somwang N. , Porntheeraphat S. , Pratontep Sirapat , Sophitpan S. , Nukaew J. , Hruanun C. , Poyai Amporn
Published: January 2010

Titanium nitride (TiN) film has been widely used as a diffusion barrier layer for VLSI contact metallization because TiN is an excellent barrier against inter-diffusion between Al and Si substrate or silicide. In this work, we studied the properties of TiN films deposited by DC magnetron sputtering with varying N2:Ar flow rate ratio in order to optimize growth conditions and film properties provided for Al diffusion barrier purpose. The TiN films were deposited at the constant pressure level and sputtering time. The crystalline orientation, composition and electrical properties of deposited TiN films were characterized by XRD, AES-depth profile and Four Point Probe measurement, respectively. The XRD results show that the deposited TiN film has two preferred orientations of TiN(111) and TiN(200) planes. The highest intensity of the TiN(111) plane was obtained when the N2:Ar flow rate ratio was 3:1. The electrical resistivity was increased when the N2:Ar flow rate ratio was decreased. The minimum electrical resistivity is 127.8 μΩ-cm when the N2:Ar flow rate ratio is 3:1.
Effect of Annealing on Material Properties of Both Electrodes in Dye Sensitized Solar Cell Structure
Authors: Prachopchok P. , Thanachayanont Chanchana , Sriprapha K. , Heawchin A. , Kaewket S. , Vijitjanya P. , Sac-Kung C. , Osotchan Tanakorn
Published: January 2010

In dye sensitized solar cell structure, the transparent electrodes of tin oxide doped fluorine (SnO2:F) was coated by titanium dioxide (TiO2) and platinum (Pt) for cathode and anode electrodes, respectively. In order to achieve high efficiency solar cell, both electrodes are required to have proper crystal structure size and morphology. These can be modified during the annealing process therefore the effects of electrode annealing on their crystal structure and surface modification were investigated in this study. Thick films of TiO2 and Pt were deposited by screen printing method on 3mm thick glass substrate (Nippon Sheet Glass) coated with 500nm thick SnO2:F. The glass substrate has sheet resistance of 20 ohm/square with the optical transmission of about 70%. The mixed TiO2 powder has the diameter of about 20 nm. The screen print structure was heated for drying in the oven at 150oC for 1 hour. Then the TiO2 thick films were annealed at various temperatures from 400 to 550oC for 2 hours, while the Pt films were annealed at lower temperature from 300 to 500oC. The obtained thickness of TiO2 and Pt film after annealing become about 10 and 3 µm, respectively. The crystallinity of the films was examined by x-ray diffraction while the surface morphology of both films was determined by atom force microscopy. To investigate the relation between material structure and the performance of the solar cell, the annealed electrodes at different temperature were used to fabricate the dye sensitized solar cell structure with standard rutherium(II) (N719) dye and then the current voltage characteristic was measured under light with air mass of 1.5. It found that the structure with higher anneal temperature electrode exhibited higher power conversion efficiency originating from the higher short circuit current density of better crystallinity and higher surface area.
Performance of Bioactive Hydroxyapatite Coating after Soaking in Simulated Body Fluid
Authors: Suvannapruk Waraporn , Wasoontararat Kitiya , Suwanprateeb Jintamai
Published: January 2010

In this study, in vitro acellular bioactivity and tensile bonding strength of hydroxyapatite (HA) coating synthesized by sol-gel technique after long-term storage in simulated body fluid (SBF) for up to 32 days were studied. After soaking in SBF, it was observed that new bone-like apatite layer was formed on the coating indicating the bioactive nature. Bonding strength of sol-gel coated rods was found to decrease with soaking times, from 55 to 30 MPa. In comparison to adhesive bonded titanium rods which were used as control specimens, the values were found to be equal or even greater in certain soaking periods. Debonding at adhesive-titanium interface was the failure mode indicating that the coating is still intact. Therefore, it could be concluded that this sol-gel coating is bioactive and the coating adhesion to substrate is sufficiently strong.
All-Solid-State pH Sensor Based on Conducting Polymer
Authors: Natedungta W. , Prissanaroon-Ouajai W.
Published: January 2010

A solid-state (free of internal electrolyte solution) reference electrode based on metallic silver is simply fabricated via a simple electrodeposition from AgNO3. Potentiometry is carried out to study the performance of the solid-state reference electrode in comparison with the commercial Ag/AgCl reference electrode. In addition, the proposed solid-state reference electrode has been integrated with the PPy-modified pH electrode to form an all-solid-state pH sensor, showing the capability of pH measurement. Absence of the internal solution leads to the pH sensor that is convenient to use and maintenance. In addition, the proposed pH sensor is possibly applied to biochemical and medical processes as well as flow infection analysis.
Control of Mechanical Properties and Permeability of Electrospun Natural Rubber with Different Composite Systems
Authors: Sithornkul Sarawuth , Threepopnatkul Poonsub
Published: January 2010

The electrospun natural rubber (NR) with two different components namely: acrylonitrile butadiene styrene (ABS) and carbon black (CB) have been extensively studied. The main objective was to investigate the mechanical properties and permeability dependency of NR/ABS and NR/CB as well as its contents. NR/CB was compounded by torque rheometer (Brabender) while ABS was dissolved with NR using tetrahydrofuran (THF) as its solvent. Sulfur was used as the vulcanizing agent in both systems. Mechanical properties were evaluated by universal testing machine and permeability was observed by water vapour permeability. The optimum conditions for electrospun NR/ABS and NR/CB non-woven mats were as follows: flow rate 30 ml/h, voltage 15 kV, collector distance 20 cm and collected on rotating circular plate at 1000 rpm. The results of mechanical properties showed that for electrospun NR/CB fiber membranes, the higher the CB loading it had, the lower its tensile strength and elongation it would be. Whilst electrospun NR/ABS fiber mats, the elongation behavior was affected by the ABS loading but not the tensile strength. For permeability, NR/CB was shown to possess relatively higher permeability than the NR/ABS non-woven mats.
Color Tolerance of Identity Color of Chulalongkorn University on General Print
Authors: Naovaprateep Niti , Koopipat Chawan , Katemake Pichayada
Published: January 2010

Chulalongkorn University has a long historical background. Pink color is known as the identity color. To be more specific on which pink colors of general prints are acceptable for the identity color of Chulalongkorn University, printed samples with the identity color were collected and measured to find the differences among the printed colors. Then the Natural Color System (NCS) colors were determined corresponding to the printed samples. The obtained NCS colors were used as samples in the experiment. A standard color was obtained from the color of pink cushion placed under Prakeaw, an emblem of Chulalongkorn University. Measurements were taken at the same specific light source as in printed samples. Comparison was then made to determine the color tolerance. A method of pass/fail tolerance was adopted to evaluate the optimum color difference between the identity color and the color of general prints by comparing the results of color measuring device against that of visual assessment. A group of 101 observers were involved to find their perception acceptability of printed pink samples against identity color or standard pink color. The color different equations, E94 and CIEE2000 were employed.
Synthesis and Characterization of CoFe2O4 Particle by PVA Sol-Gel Method
Authors: Hunyek A. , Sirisathitkul Chitnarong , Harding P.
Published: January 2010

Cobalt ferrite (CoFe2O4) is a soft magnetic material that can be used as fillers in polypropylene. This magnetic polymer composite is studied for its electromagnetic wave absorbing property. To synthesize CoFe2O4 by the polyvinyl alcohol (PVA) sol-gel method, PVA powder was dissolve in distilled water with 5%, 10% and 15% weight per volume. The solution was stirred and regulated at temperature between 60-80°C until turning into PVA gel. Fe and Co powder of atomic ratio 2:1 were then added to the PVA gel with the metal weight per gel volume 1:6, 1:10 and 1: 12. After sintering at 800°C, phases of the synthesized powder were identified by X-ray diffraction (XRD). Magnetic properties of CoFe2O4 were characterized in order to select the appropriate synthesis condition for electromagnetic wave absorbers.
Nanostructured Polycaprolactone-Inorganic Phosphate Hybrid Scaffold for Medical Applications
Authors: Kaewsichan Lupong , Kaewsrichan Jasadee , Chuchom Thitima
Published: January 2010

New hybrid macroporous scaffolds of polycaprolactone (PCL)/tricalcium phosphate (TCP) were developed by taking into account mechanical properties of the bone to be replaced. FTIR spectra indicated the coating of TCP onto the polymer, providing hydrophilic surfaces necessary for cells to attach. As determined by DSC, the depression of PCL melting point suggested a uniform distribution of PCL within the TCP matrix. SEM micrographs revealed pores of irregular shapes varying from 100-200 µm in size in the resultant structures. Indeed, the pore morphology was precisely determined by the leached particles. The scaffolds could tolerate the impact of at least 5.6 kNm2, making them suitable for use as artificial bones of skull, clavicle and ribs. Rat bone stroma attached and survived on the scaffolds, indicating biocompatible of the used materials. Therefore, the prepared scaffolds would be applicable for bone tissue engineering in the near future.
Electrical Characteristics of DLC Deposited by RF Inductively Coupled Plasma Process
Authors: Paosawatyanyong Boonchoat , Muakngam A. , Thitianan S.
Published: January 2010

A Radio Frequency Inductively Couple Plasma Reactor (RFICP) was designed and set up for DLC deposition onto aluminum substrates using CH4-H2 admixture precursor gas. Plasma parameters of the discharge during the deposition process were measured using Langmuir probe technique. The structure and morphology of the DLC films were characterized by SEM and Raman spectroscopy. SEM images show granule morphology which yield smaller grain size with increasing of RF power. It was found that the structure and composition of DLC films are controlled by changes in the RF power. Raman spectrum of DLC films show two typpical modes of the graphite lattice labelled as ‘G’ and ‘D’ modes. The G peak position shift to higher wave number and the ratio of the peak intensity ID/IG increases with increasing RF power. DLC samples yield good ohmic characteristics with decreasing resistivity in films grown at higher RF power. Both electrical and structural characteristics indicated that the films contain more graphitic content of sp2 hybridization with increasing RF power in the plasma process.
Anti-Tumour Effect of a Chitosan Delivery System for Doxorubicin
Authors: Tan Mei Lin , Choong Peter F.M. , Dass Crispin R.
Published: January 2010

Used against a variety of tumours, doxorubicin (DOX), causes multiple side-effects in patients, especially in high doses required to control tumour growth. A drug delivery system (DDS) was developed to deliver DOX. Through DOX encapsulation into chitosan DDS, novel DOX microparticles (DMPs) were formed. Multiple optimisation steps produced DMPs which caused tumour cell death. Treatment of mice bearing tumours with DMP decreased tumour growth and spread, with no visible side-effects. There are plans to evaluate this delivery vehicle more closely towards clinical development and testing.
Photoactivity of TiO2 Films on Glass Substrate for Cyanide Degradation
Authors: Junin Chabaiporn , Limthongkul Pimpa , Thanachayanont Chanchana
Published: January 2010

A comparative study of TiO2 films on glass substrates produced by sol- gel dip coating technique using two types of titania precursors were performed. The two types of titania solutions with and without triton x-100, poly (ethylene glycol) were used to prepare the films. The dip coated films were dried at 55°C and calcined at 400 - 600°C for 4 hrs resulting in smooth and transparent TiO2 films. Morphology and phases of the films were investigated using SEM and XRD, respectively. Anatase phase was found to be dominant in all samples with various degree of crystallinity depending on the calcination temperatures and whether the templating agents were used. The templating agent was found to effectively inhibit the crystallization and growth of the crystallites of the films. Morphology of the TiO2 particles was found to be in the nanoscale level. All films fabricated were found to effectively degrade cyanide even though no obvious relations between processing method including calcinations temperature and the use of template were found.
Surface Modification of Alumina Nano-Particles by UV-Induced Grafting Polymerization of 2-Hydroxyethyl Methacrylate
Authors: Yantaboot K. , Maensiri S. , Khansawai Paveena , Amnuaypanich Sittipong
Published: January 2010

Alumina nano-particles was grafted with poly(2-hydroxyethyl methacrylate) (PHEMA) utilizing the sequential method; that is, the alumina surface was first rendered with initiator, benzophenone, by UV-irradiation followed by the grafting polymerization of HEMA on the surface which was initiated thermally and propagated via the free-radical polymerization. FT-IR spectroscopy confirmed the successful grafting of PHEMA onto the alumina surface. Determined by thermalgravimetry (TG), the amount of benzophenone on the alumina surface was found to increase with the UV-irradiation time; however upon grafting of PHEMA, the amount of grafted-PHEMA was the same irrespective of the reaction time. The glass transition temperature (Tg) of grafted-PHEMA on alumina particles was approximately 93 °C that is higher than that of PHEMA which has Tg around 85 °C. This indicates the more restricted movement of grafted-PHEMA compared with the ungrafted-PHEMA.
Corrosion Behavior of Magnesium Alloys in Biomedical Environments
Authors: Eliezer Amir , Witte F.
Published: January 2010

High rates of degradation in corrosive media represent the Achilles heel of Mg alloys, which hinders their applications in various areas, particularly in prosthetics. We present an investigation of the degradation behavior of magnesium alloy AZ91D and AM50 in different solutions that simulates bodily fluids. The degradation rate is shown to be significantly reduced by different Al contents in the alloy. Furthermore, the corrosive solutions containing protein influenced on the oxidation behavior of the studied alloys
Corrosion Control in the Desalination Industry
Authors: Valdez Benjamin , Schorr Michael
Published: January 2010

Desalination is a viable solution to the 21th century´s shortage of freshwater. The most widely used desalination processes are thermal and membrane. Other modern techniques apply solar and electrical energy for evaporation and electrodialysis. Many desalination plants (DP) are located in desertic/arid regions with a harsh climate and limited rainfall. About one-fifth of the DPs operate in the Middle East, with Saudi Arabia producing half of the world desalted water. The final selection of materials of construction for plant equipment must be a compromise between technological and economic factors. Corrosion problems and their solutions in several DPs in the Middle East, USA and Mexico are presented.
Effect of H2S on Corrosion in Polluted Waters
Authors: Quintero-Núñez Margarito , Valdez Benjamin , Schorr Michael
Published: January 2010

There is a deep universal concern today about the influence of pollutants on the environment including soil, air and in particular water, and about their effects on the durability of engineering materials and the deterioration of structures and the infrastructure. Water pollutants affect the terrestrial, atmospheric and aquatic environments, and even when present at very low levels of a few ppm may impair human health, aquatic life and water quality. The avoidance of water pollution is, therefore, an important part of water resource management. The present work provides an overview of the effects of hydrogen sulfide (H2S) on corrosion in polluted waters, including sea, river, brackish, geothermal and sewage waters.
The Correlation between Plastic Deformation and Surface Properties of SiC Structured AM50 Magnesium Alloy
Authors: Eliezer Amir , Karbian A. , Kiperwasser E. , Koritny A.
Published: January 2010

This research has focused on understanding the correlation between the raw material, processes, microstructure and corrosion behavior of AM50 containing SiC particles magnesium sheet. The magnesium sheets were produced from cast ingot AM50 containing different amount of SiC particles. The magnesium sheets were exposed to 3.5 % NaCl solution with Mg(OH)2 , pH=10.5 in room temperature. The influence of SiC particles on the micro-galvanic corrosion was studies by Scanning Kelvin Probe Force Microscopy.
Thickness of Concrete Cover for Corrosion Protection of Steel Reinforcement and Crack Control
Authors: Farhat Rina
Published: January 2010

Thickness of concrete cover positively affects both the protection of the steel against corrosion and the safe transmission of bond forces. On the other hand it affects Crack control inversely, larger concrete cover causes larger crack width, and as a result it yields reduction in the protection of the steel against corrosion. The influence of the distance between the centroid of the longitudinal reinforcement to the neutral axis, and the stress in the tension steel, on the crack width and Crack control, will be examined. Computations will be done using personal computer program developed for nonlinear analysis of rectangular reinforced concrete sections in flexure. The analysis is performed using Stress-strain relationship for confined concrete: parabola – rectangle with decending branch to 0.3 fc at Ecu, followed by horizontal branch. Stress-strain diagram for reinforcing steel, with an inclined top branch with a strain limit of E su . Beams and slabs elements sections will be examined for the flexural moments from the external loads acting at serviceability limit state. This paper will introduce by computing the concrete fibers stresses and strains over the height of the section, for different element thickness, the influence of tension steel stresses and concrete cover thickness on crack control and corrosion protection of steel reinforcement.
Microbially Induced Corrosion in the Mineral Processing Industry
Authors: Stoytcheva Margarita , Valdez Benjamin , Zlatev Roumen , Schorr Michael , Carrillo Monica , Velkova Zdravka
Published: January 2010

A method for real time determination of microbiologically influenced corrosion (MIC) rate provoked by bacteria Thiobacillus Ferrooxidans was developed and applied on carbon steel samples. It is based on biological oxygen demand (BOD) determination of solutions contained Thiobacillus Ferrooxidans performed by the application of a Clark type oxygen probe in especially designed measuring cell.
Corrosion Behavior of Surfaced AM50 Magnesium Alloys under Stress Conditions
Authors: Eliezer Amir
Published: January 2010

Micro-arc oxidization of AM50 magnesium alloys was studied. The influence of micro-arc oxidization process was investigated; phase structure were analyzed using X-ray diffraction (XRD). Open circuit potential (OCP) and electrochemical impedance spectroscopy (EIS) were used to evaluate the corrosion resistance of ceramic coatings formed on magnesium alloys under stress conditions. XRD analyses indicate that the ceramic coatings fabricated on the surface of magnesium alloys by micro-arc oxidization are composed of spinel phase MgAl2O4 The corrosion resistance of ceramic coatings is improved compared with magnesium alloy substrate.
Adsorption Properties of Vermiculite for Simulative Radionuclide Sr
Authors: Yang Wei , Peng Tong Jiang , Miao Zhao
Published: January 2010

Based on good cation exchange property of vermiculite，the adsorption of vermiculite for simulated radionuclide Sr was studied by the static adsorption method. The adsorption behaviors and the effect of the experimental conditions were investigated. The results show that the saturated adsorption capacity of vermiculite sample for the simulated radionuclide Sr was 8.246×10-2 mmol/g. The suitable pH value ranged from 4 to 11, the balanceable adsorption time was 3d, and the suitable temperature was 30°C. The main adsorption type was cation exchange. The adsorption mechanism can be described by Langmuir and Freundlich models. It acts better in accord with Langmuir model, and the correlation coefficient is 0.99974. This experimental study has important significance on low concentration of Sr radioactive waste liquid treatment.
Modification of Activated Carbon From Sewage Sludge to Improve Desulfurization With γ-Al2O3
Authors: Fan Xiao Dan , Zhang Xiang Kai
Published: January 2010

The aim is to modify the activated carbon from sewage sludge with γ-Al2O3 by sol-gel, investigate its performances on the SO2 adsorption and the desulfurization mechanisms in the presence of gaseous oxygen. The modification of the activated carbon from sewage sludge was carried out by adding γ-Al2O3 to improve the SO2 adsorption in a simulated flue gas. The results indicated that γ-Al2O3 porous membranes addition was very effective in promoting the BET area and pore volumes of the activated carbon from sewage sludge. γ-Al2O3 porous membranes in the presence of gaseous oxygen had much effect on the adsorption performance and benefited the SO2 adsorption capacity. The physically adsorbed adsorption took place first. And the following reactions should be occurring on the active sites (*) because of the specific pore construction, BET area and surface functional groups on γ-Al2O3/activated carbon from sewage sludge: (1)SO2 + *→SO2* , (2) O2 + *→O2* , (3)SO2* + O2* → SO3* , (4) 3SO3* + Al2O3 → Al2(SO4)3.
Preparation and Characterization of Polyurethane Rigid Foam/Expanded Perlite Thermal Insulation Composites
Authors: Ai Ming Xing , Cao Li Qiang , Zhao Xiao Long , Xiang Zhen Yu , Guo Xiang Yong
Published: January 2010

The polyurethane rigid foam/expanded perlite thermal insulation composites (PPC) have been prepared by mixing the two-component polyurethane and expanded perlite. The effects of proportioning of constituents on the mechanical and thermal properties of PPC were investigated. The results showed the compressive strength of PPC was improved and good heat-insulating was achieved, which would promote the application of polyurethane rigid foam and expanded perlite in buildings.
Preparation of Expanding Vermiculite by Chemical and Microwave Methods
Authors: Miao Zhao , Peng Tong Jiang , Xi Yong Guang , Yang Wei
Published: January 2010

Based on the characters of expanding and layer adsorbing of vermiculite，industrial vermiculite samples from Weili Mine of Xinjiang Province were expanded by both chemical and microwave chemical methods. The influences to the exfoliation ratio of different parameters such as concentration of hydrogen peroxide, power of the microwave, heating time, ratio of solid-liquid, immersion time were discussed. And the expanded mechanism of vermiculite was also analyzed. The results indicate that the expanded times increase with the increasing of concentration of hydrogen peroxide, and the best expanding point appears when the concentration of hydrogen peroxide is 30%. The solid-liquid ratio of vermiculite and hydrogen peroxide has little effect on the expanding of vermiculite. The vermiculite samples could be expanded 8.5 times by heated 2 min under 800W microwave power after immersion for 12 h when the concentration of hydrogen peroxide is 30%. As a result, the vermiculite could be expanded because of the oxygen pressure produced by the decomposition of hydrogen peroxide into the vermiculite interlayer. When using the microwave chemical method, the pressure of both oxygen and interlayer water lead to the increases of the expanded times. And exfoliation vermiculite plays an important part in energy-saving and environmental treatment.
Preparation of Phase Change Building Materials
Authors: Li Hai Jian , Ji Zhi Jiang , Xin Zhi Jun , Wang Jing
Published: January 2010

The types and characteristics of phase change materials were discussed. With respect to application in building materials, the PCM should have more attractive properties including high latent heat values, stability and proper melting point, inflammability, corrosiveness and supercooling. Phase change building material (PCBM) was prepared using vacuum absorption method and tested by means of Differential Scanning Calorimetry(DSC) and Scanning Electron Microscopy(SEM). The testing results have shown that organic PCM was absorbed into the holes of inorganic carriers completely and distributed evenly with stable performances. It is concluded that the composite PCM has steady temperature-adjusting function and the preparation means is acceptable.