Skip Navigation LinksVolume : Volume 19 No.1 2010

  
  
  
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thermal_conductivity_estimation_of_oxide_nanofluid_in_water_influence_of_particle_properties.pdfTHERMAL 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.pdfTHE 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.pdfSYNTHESIS 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.pdfSURFACTANT 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.pdfSILVER 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.pdfPREPARATION 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.pdfPRELIMINARY 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_for_electrochemical_capacitors.pdfOPTIMIZATION 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_based_nanoparticle_gene_delivery_system.pdfGENE 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.pdfFABRICATION 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.pdfELECTROPHORETIC 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.pdfEFFECT 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_application.pdfCONJUGATION 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_by_ultrasonic_waves_0.pdfA 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_by_ultrasonic_waves.pdfA 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