| | Count= 15 | | |  |  | THERMAL CONDUCTIVITY ESTIMATION OF OXIDE NANOFLUID IN WATER - INFLUENCE OF PARTICLE PROPERTIES | | ABSTRACT :
The theoretical and experimental analysis for the determination of heat transfer coefficient is mostly based on metallic oxide nanofluids by different investigators. Information regarding the properties at different volume concentration and temperature is required for the estimation of heat transfer coefficient. The two most important properties which are experimentally determined are viscosity and thermal conductivity. Investigators have been estimating the properties of metallic oxide nanoparticles at different ambient temperatures and with different base liquids. The present work is an attempt to analyse the available data and obtain a single linear regression equation for the estimation of thermal conductivity of water based nanofluids considering particle size, volume concentration and temperature useful for designer. It has been observed that the ratio of heat capacities of the nanoparticle to nanofluid has a profound influence on the values of thermal conductivity. The equation could predict the values of thermal conductivity ratio of ZnO nanofluid satisfactorily. The inclusion of heat capacity ratio term in the regression equation has vastly improved the predictability of thermal conductivity of water based nanofluids.
KEYWORDS : Nanofluid, thermal conductivity, regression equation , heat capacity ratio
Author: K.V.Sharma, W.H.Azmi, Rizalman Mamat, S.M.Zuhairi, K.Kadirgama, R.A.Bakar | | Year:
2010 | | | | THE STRUCTURAL AND ELECTRICAL PROPERTIES OF AG/POLYANILINE (PANI) CORE-SHELL NANOCOMPOSITE | | ABSTRACT :
The formation of Ag nano particles using PVP (polyvinylpyrrolidone) as stabilizer to limit the growth of particles have been prepared by thermal process then coated by PANI (polyaniline) 'in situ' encapsulation chemical method, in which PANI was synthesized from its aniline monomer in the presence of sulfuric acid at 5°C. The objective of fabricating Ag/ PVP coated with PANI was to improve the solubility of PANI in organic solvents. The morphology of Ag/PANI nanocomposites was studied using TEM and SEM which showed that the particle size increased with increasing Ag concentration in the composite, owing to the aggregation effect. FT-IR spectroscopy and Energy Dispersion X-ray (EDX) have been used to characterize the resulting materials. The results showed that the presence of Ag nanoparticles in the composite has no effect on the formation of PANI (ES) form. The scope of our study was achieved by producing partially soluble and conductive PANI and Ag/PAN I core-shell, 15 mg/ 10 ml, 20 mg/ 10 ml and 2.6x 10-3 S/cm, 1.1x 10-3 Siem, respectively.
KEYWORDS : Core-shell nanocomposites, polyaniline, silver nanoparticles
Author: M. Alshaikh and Rosian Md Nor
| | Year:
2010 | | | | SYNTHESIS OF SILICON NANOWIRE ARRAYS AND CORE-SHELL HETEROSTRUCTURE$ VIA ELECTROCHEMICAL GALVANIC DISPLACEMENT | | ABSTRACT :
Large-area vertically aligned silicon nanowire (SiNW) arrays have been successfully synthesized in an aqueous solution containing AgN03 and HF on p-type Si (100) substrate by self-selective electroless etching process. The temperature of the electrolyte and the etching time were varied in order to achieve different stages of nanowire formation. Diameters of the SiNWs varied from 50 to 200 nm and their lengths ranged from several to approximately a few tens of µm, depending on the etching time and temperature used. Te-Si core-shell heterostructures were subsequently obtained by galvanic displacement of the SiNWs in an acidic HF electrolyte containing HTeO/ ions. Growth study on the SiNWs and Te-Si core-shell heterostructures is presented using various microscopy, diffraction and probe-based techniques for structural, morphological and chemical characterizations.
KEYWORDS : Self-selective electroless plating, galvanic displacement, nanowire arrays
Author: Ng Inn Khuan, Kok Kuan Ying, Siti Salwa Zainal Abidin, Nur Ubaidah Saidin | | Year:
2010 | | | | SURFACTANT ASSISTED SYNTHESIS OF COBALT NANOPARTICLES VIA POLYOL ROUTE | | ABSTRACT :
Cobalt nanoparticles were successfully prepared by polyol method with the assistant of a surfactant, i.e. sodium dodecyl sulfate (SDS). Transmission Electron Microscope (TEM) and Scanning Electron Microscope (SEM) were employed to calculate the particles size distribution and observation of the morphology of cobalt nanoparticle. X-Ray Diffraction (XRD) confirmed the co-existance of HCP- and FCC- cobalt in the same cobalt sample. Pure cobalt powder was obtained and confirmed by Energy Dispersive X-ray Analysis (EDX). Ultraviolet-visible spectrophotometer (UV-Vis) had been employed to investigate the evolution of cobalt nanoparticles in the synthesis. Effects of surfactants on the formation of cobalt nanoparticles were investigated and discussed.
KEYWORDS : Cobalt narioparticles, polyol , sodium dodecyl sulphate
Author: C.S. Khe, A. Azizan, Z. Lockman | | Year:
2010 | | | | SILVER ION RELEASE FROM CHITOSAN-AG COMPOSITE USING VOLTAMMETRIC METHOD FOR POSSIBLE WOUND TREATMENT APPLICATION | | ABSTRACTS :
The antimicrobial and antiviral actions of Ag demonstrated to be effective at killing a broader range of bacteria including antibiotic-resistance bacteria. Numerous studies have been performed on silver-based materials including silver-polymer composites. In this work, UV photo-reduction process was used to produce silver nanoparticles from AgN03 in chitosan solution in which the silver ions (Ag+) is reduced to (Ag 0 ). The antimicrobial activity of silver is dependent of the silver cation Ag+ which binds strongly to electron donor groups in biological molecules containing sulphur, oxygen or nitrogen. It is therefore very important to study the release of the active species of Ag+ to a pathogenic environment in order to be effective. As the antimicrobial efficacy's limit and concentration of silver ions released from the chitosan composites lies in the parts per billion ranges, an accurate measurement of the low concentration silver is indispensable. The present study used voltammetric analysis to measure the very low concentration of silver released into the buffer medium. Transmission Electron Microscopy (TEM) analysis was used to demonstrate the existence of silver nanoparticles in the chitosan solution.
KEYWORDS : Antimicrobial, silver nanoparticles, chitosan, voltammetry
Author: Nor Shahida Kader Bashah, Fatimah Suhaily Abdul Rahman, Ahmad Fuad Yahya Ismail Zainol and Kartini Noorsal | | Year:
2010 | | | | PREPARATION AND IN-VITRO EVALUATION OF BLANK AND PIROXICAM-LOADED LIPOSOMES | | ABSTRACT :
Liposomal drug delivery system, a promrsmg lipid-based nanoparticle technology, was used in the present work to - encapsulate - a lipophilic non-stero idal anti-inflammatory drug, piroxicam. A simple proliposomes method was optimised for rapid production of blank and drug-loaded liposomes . Various in-vitro techniques were selected , modified and validated for the evaluation of drug entrapment and size profiles of prepared liposomal samples. In the present study, a rapid and specific isocratic High Performance Liquid Chromatography (HPLC) method was successfully develope and employed for quantification of piroxicam in prepared liposomal samples. Dimethylsulfoxide was tested to be the most appropriate solvent system for liposomal samples preparation. Results showed that Pro-lipo™ Duo allowed higher amount of piroxicam to be entrapped into liposomes and gave a higher percentage of entrapment efficiency when compared to Pro-lipo™ C. However, Pro-lipo™ C produced smaller and more homogenous liposomes samples compared to those using Pro-lipo™ Duo. In conclusion, current work successfully demonstrated optimised procedures in preparation and evaluation of liposome-based drug delivery system for piroxicam.
KEY WORDS : Liposomes, proliposomes, piroxicam, HPLC, encapsulation, particle size
Author: H.S. Chiong,M.N. Somchit., Y. Azhar , S.G.M. Ong and K . H. Yuen | | Year:
2010 | | | | PRELIMINARY ULCEROGENIC EVALUATION OF PIROXICAM-LOADED LIPOSOMES | | ABSTRACT :
Liposomal drug delivery system, a promising lipid-based nanoparticle technology, was used in the present work to encapsulate lipophilic non-steroidal anti-inflammatory drug, piroxicam. A 14 days sub-acute study was conducted to gather the preliminary toxicological information. All treated samples were freshly prepared prior to experiments. Rats (male Sprague Dawley; body weight 180-220 g; n=6/group) were intragastically fed with samples once a day in the morning. All rats were sacrificed by overdose of diethyl ether and median laparotomy was performed to isolate the stomach, liver and kidney. Stomach was opened along the greater curvature, rinsed carefully with saline and blotted dry before subjected to macroscopic evaluation. Stomach lesions were characterized into 6-score value. Stomach was cut and fixed in 10% formalin before subjected to routine histopathology processing. Tissues were observed under light microscope and lesion was characterized based on cellular morphological changes. Rats dosed with piroxicam (12, 18 and 24 mg/kg) exhibit significant ulcer scoring when compared to negative control group. Although the ulcer score for other treatment groups (blank liposomes and piroxicam-loaded liposomes) were found to be elevated, no statistically significant difference was obtained. Histologically, encasulation reduced the gastric inflammation. In conclusion, findings showed that the encapsulation of piroxicam into liposomes had the potential to reduce gastric ulceration problem in animal model.
KEYWORDS : Piroxicam, liposomes, nanoparticles, drug delivery
Author: Y. Azhar , H.S. Chiong, S. Malarvili, M.N. Somchit and K.H. Yuen | | Year:
2010 | | | | OPTIMIZATION OF ELECTROPHORETIC DEPOSITED MANGANESE OXIDE THIN FILMS AS ELECTRODE MATERIALS FORELECTROCHEMICAL CAPACITORS | | ABSTRACT :
Nanostructured thin films of tetrapropylammonium manganese oxide (TPA-MO) were prepared by depositing TPA-MO nanoparticles in the form of stable colloidal suspension - directly onto supporting stainless steel plates using the electrophoretic deposition technique. Electrochemical characterization by cyclic voltammetry indicated that TPA-MO thin films exhibited high charge capacity, good cycling reversibility and stability in -- 1.0 M Na2S04 aqueous electrolyte. TPA-MO thin films with optimized film thickness, mass loading, and microstructure exhibited enhanced electrochemical properties with a specific capacitance of about 700 Fig. These films are therefore potential electrode materials for the fabrication of electrochemical capacitors.
KEYWORDS : microstructure Nanostructures, thin films, oxides, electrochemical properties,
Author: Suh Cem Pang, Suk Fun Chin and Yen Yuan Tay | | Year:
2010 | | | | GENE TRANSFER INTO MOUSE AIRWAYS USING POLYCATION BASEDNANOPARTICLE GENE DELIVERY SYSTEM | | ABSTRACT :
The emergence of gene therapy has attracted attention in the recent years as this technology enables a myriad of diseases to be treated at the root of the cause. The generation of a non-viral gene delivery vector with high transfection efficiency is highly required for this treatment strategy to be successful. Dextran-spermine (D-SPM) is a biodegradable polycation capable of compl~xing with plasmid DNA (pDNA). Yet, no study has been performed on its transfection efficiency in the lung via intranasal delivery technique. In this study, first, we showed that the in vitro transfection efficiency for D-SPM is higher than its PEGylated form. Next, we determined the optimal conditions for reporter gene expression in the lungs of mice via instillation delivery of the D-SPM/pDNA complex. Three conditions tested were: (i) different weight-mixing ratios of the complex, (ii) amount of pDNA in the complex and (iii) its expression time-point profile. The size of the D-SPM/pDNA complex was also evaluated. Results showed that the maximum reporter gene expression level in the mouse lungs was observed at weight-mixing ratio of 16, with 13.5 µg of pDNA and at day 1 post-treatment. The size measurement of the complexes was evaluated at different DNA concentrations with weight-mixing ratio kept at the ratio that gave the highest reporter gene activity. The results show that the sizes of the complexes were in a nanometer range and were directly proportional to the amount of pDNA. In conclusion, this study has shown that the D-SPM/pDNA is a polymeric nanoparticle able to transfect mouse lungs, albeit at moderate efficiency.
KEYWORDS: Gene delivery, lung instillation, non-viral vector, nanoparticle, gene therapy
Author: Wai Yeng Wendy-Yeo , Sabariah Abdul Rahman , Rozita Rosli and Syahril Abdullah | | Year:
2010 | | | | FABRICATION AND CHARACTERIZATION OF ELECTRODEPOSITED ONE-DIMENSIONAL NANOSTRUCTURES | | ABSTRACT :
Electrochemical synthesis including electrodeposition, electroless deposition, and galvanic displacement offers tremendous versatility as a cost-effective method for synthesizing one-dimensional nanostructures such as nanowires, nanotubes, as well as radial and axial heterostructures. In this study, high aspect ratios ferromagnetic nickel nanowires with well-controlled dimensions and structures were first synthesized via template-assisted electrochemical deposition using anodized alumina membranes as scaffolds. Co-axial heterostructures or nanotubes were subsequently synthesized by galvanically displacing the sacrificial Ni nanowires with Te, Pd and Ag. It was found that the orientations of the electrodeposited Ni nanowires were governed by the deposition current and electrolyte conditions, while the composition and microstructural transformation of the nanowires via galvanic displacement process were governed by the temperature, reaction time and concentration of the electrolytes. Structural evolution of the nanostructures obtained was investigated using various microscopy, diffraction and probe-based techniques and the growth mechanisms involved were discussed.
KEYWORDS : Template~assisted electrodeposition, galvanic displacement, nanowires
Author: Kok Kuan Ving, Ng Inn Khuan, Nur Ubaidah Saidin, Nurazila Mat ZSiti Salwa Zainal Abidin and Nosang V. Myung | | Year:
2010 | | | | ELECTROPHORETIC DEPOSITION OF MULTI-WALLED CARBON NANOTUBES ON STAINLESS STEEL (SS) FOILS | | ABSTRACT :
The effect of oxidation on the structural of MWCNTs through nitric acid has been studied. Raman spectroscopy analysis clearly revealed that the nitric acid treatment under reflux conditions suffered the highest degree of degradation and additional defect generation on the graphitic network and this would greatly aid the dispersion of CNTs in ethanol to form a stable and homogenous CNTs suspension. The amount of charger salt that was added into the suspension also influenced the microstructure of the CNTs films, as shown by the SEM analysis. SEM and -EDX analyses also revealed that deposition from lower concentration of charger salt in the CNTs suspension produced a more uniform CNTs film with lower magnesium and oxygen content compared to CNTs films deposited from higher content of charger salt suspension.
KEYWORDS : Carbon nanotubes, coating, charger salt, electrophoretic deposition, deposition voltage
Author: Siti Hajar Kasim and Abdul Hakim Hashim | | Year:
2010 | | | | EFFECT OF CLAY ORGANO-MODIFIER ON THE PROPERTIES OF NATURAL RUBBER BASED NANOCOMPOSITES | | ABSTRACT :
Natural Rubber I Clay nanocomposites were prepared with commercially available organophilic Montmorillonite (MMT) by melt compounding. In this study, two types of modified montmorillonite with different level of polarities, namely Cloisite 15A (C15A - modified MMT with quaternary ammonium) and Cloisite 308 (C30B - modified MMT with ternary ammonium) were used. The effect of organoclay type in rubber compound was analysed through cure characteristic and mechanical properties. In addition, the rubberfiller interaction was studied by the crosslink density and bound rubber content while, the dispersion state of the organoclay was investigated by X-ray diffraction and microscopy analysis. The results indicate that both organoclays accelerate the vulcanization process but more pronounced for the NR/C30B nanocomposites as confirmed by a decrease in the cure time and scorch delay. However, the mechanical tests showed that when loaded with 10 phr C15A, the modulus, tensile, tear strength and hardness of the nanocomposites were higher than those containing C30B at the same filler loading. It is suggested that, a significant improvement in the NR/C15A nanocomposites' properties relate to better dispersion of the filler in the rubber matrix at nanolevel as well as to the similarity of the polarity with rubber.
KEYWORDS : Montmorillonite (MMT), organoclay, polarity and natural rubber nanocomposite
Author: Nik lntan Nik Ismail, Siti Salina Sarkawi and Che Su Mt Saad. | | Year:
2010 | | | | CONJUGATION OF POLYAMIDOAMINE'-METHOTREXATE USING GLUTARIC ACID AS SPACER FOR POTENTIAL DRUG DELIVERY | | ABSTRACT :
Dendrimers are perfect artificial macromolecules with well-defined shape and their suitability for drug delivery is affected by charge, end functionality, generation number and molecular weight. In this study conjugated polyamidoamine (PAMAM generation 4) with methotrexate (MTX) using glutaric acid (GA) as a spacer was studied. To initiate the conjugation, we have tailored the amine end functional group of PAMAM with carboxylate to lower the reactivity and the steric hindrance of the drug. The glutaric acid was first linked to methotrexate before conjugating them with PAMAM to get a relatively high payload. The conjugation of PAMAM-GA-MTX was confirmed through UV-Vis, FTIR, 1H NMR and DSC.
KEYWORDS : Conjugation, steric hindrance, functional group.
Author: Norhidayah Abu, Siti Noorzidah Mohd Sabri, Azreena Mastor, Kartini Noorsal | | Year:
2010 | | | | A NOVEL FORMULATION AND OPTIMIZATION OF ASPIRIN NANO-EMULSION PREPARED BY CAVITATION INDUCED BYULTRASONIC WAVES | | ABSTRACT :
The preparation of poorly water soluble drugs in the form of nano-emulsion is of increasing interest in the current drug delivery system, as it appears as an excellent drug vehicle to facilitate the delivery of hydrophobic pharmaceutical ingredients into gastrointestinal tract, thereby improve the drug oral bioavailability. In the present study, an energy efficient ultrasonic cavitation method was utilized to prepare a well- optimized formulation of aspirin nano-emulsion by using a 20 kHz ultrasonic horn processor. It was found that the optimum level in terms of emulsion composition, acoustic amplitude, and ultrasonic processing time is crucial to achieve minimum droplet size. The present paper demonstrated that 0/W nano-emulsions system of 20 wt% Lauroglycol® FCC and balance water with average droplet diameter as low as 232 nm could be achieved with the presence of 5 wt% Cremophore-EL as surfactant. Results are comparable to those emulsions prepared with a magnetic stirrer and an ultra-turrax homogenizer. The microscopic results showed that the emulsion droplet after 1min ultrasound irradiation were almost spherical in shape and excellently stable with no apparent flocculation and coalescence over the two-week storage at room temperature. It is strongly suggested that the use of ultrasound for preparation of 0/W aspirin nano-emulsions was superior in terms of droplet size and energy efficiency, as compared to conventional magnetic mechanical devices.
KEYWORDS: Nanoemulsion, aspirin, bioavailability, ultrasound, cavitation, efficiency
Author: Siah Ying Tang, Manickam Sivakumar | | Year:
2010 | | | | A NOVEL FORMULATION AND OPTIMIZATION OF ASPIRIN NANO-EMULSION PREPARED BY CAVITATION INDUCED BYULTRASONIC WAVES | | ABSTRACT :
The preparation of poorly water soluble drugs in the form of nano-emulsion is of increasing interest in the current drug delivery system, as it appears as an excellent drug vehicle to facilitate the delivery of hydrophobic pharmaceutical ingredients into gastrointestinal tract, thereby improve the drug oral bioavailability. In the present study, an energy • efficient ultrasonic cavitation method was utilized to prepare a well- optimized formulation of aspirin nano-emulsion by using a 20 kHz ultrasonic horn processor. It was found that the optimum level in terms of emulsion composition, acoustic amplitude, and ultrasonic processing time is crucial to achieve minimum droplet size. The present paper demonstrated that 0/W nano-emulsions system of 20 wt% Lauroglycol® FCC and balance water with average droplet diameter as low as 232 nm could be achieved with the presence of 5 wt% Cremophore-EL as surfactant. Results are comparable to those emulsions prepared with a magnetic stirrer and an ultra-turrax homogenizer. The microscopic results showed that the emulsion droplet after 1 min ultrasound irradiation were almost spherical in shape and excellently stable with no apparent flocculation and coalescence over the two-week storage at room temperature. It is strongly suggested that the use of ultrasound for preparation of 0/W aspirin nano-emulsions was superior in terms of droplet size and energy efficiency, as compared to conventional magnetic mechanical devices.
KEYWORDS: Nanoemulsion, aspirin, bioavailability, ultrasound, cavitation, efficiency
Author: Siah Ying Tang, Manickam Sivakumar | | Year:
2010 | |
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