Displaying publications 361 - 380 of 1357 in total

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  1. Tham L, Roslindar Nazar
    Sains Malaysiana, 2012;41:1643-1649.
    A steady laminar mixed convection boundary layer flow about an isothermal solid sphere embedded in a porous medium filled with a nanofluid has been studied for both cases of assisting and opposing flows. The transformed boundary layer equations were solved numerically using an implicit finite-difference scheme. Three different types of nanoparticles, namely Cu, Al2O3 and TiO2 in water-based fluid were considered. Numerical solutions were obtained for the skin friction coefficient, the velocity and temperature profiles. The features of the flow and heat transfer characteristics for various values of the nanoparticle volume fraction and the mixed convection parameters were analyzed and discussed.
    Matched MeSH terms: Nanoparticles
  2. Chiu W, Too S, Daud S, Rashid N, Chia M, Rahman S, et al.
    Sains Malaysiana, 2014;43:941-945.
    In the present study, we report the size distribution study on the iron oxide (Fe304) magnetic nanocrystals (Ncs), which have been synthesized by using green chemistry approach with palm-oil based carboxylic compound (oleic acid) as capping ligands . The Fe304 Ncs were prepared by one pot reaction under non-hydrolytic approach. With the assistance of oleic acid that plays the role as effective capping-ligands , we showed that the Fe304 NCs that are highly monodispersed in size and shape can be synthesized by scrupulously controlling the reaction time. The diameter of Fe304 Ncs can be tuned within the range of 4.0-18.0 nm and exhibit very uniform morphology, which are spherical in shape. Current synthetic approach offers a cheap, environmentally benign and excellent repeatability route in large-scale production of high-quality magnetic Fe304 Ncs if compared to the preceding reports.
    Matched MeSH terms: Nanoparticles
  3. Ooi SY, Ishak Ahmad, Mohd Cairul Iqbal Mohd Amin
    Sains Malaysiana, 2015;44:793-799.
    In this research, a novel method was performed to obtain hydrogel with superior thermal stability by incorporation
    of cellulose nanocrystals (CNC) into gelatin based hydrogel. Glutaraldehyde was used as cross-linker due to its high
    chemical reactivity towards NH2
    group on gelatin. Different ratio of gelatin/CNC hydrogel was produced in order to study
    the effects of CNC towards the swelling behaviour and thermal stability of gelatin based hydrogel. The obtained hydrogel
    was subjected to Fourier transform infrared (FTIR) to verify that gelatin had been cross-linked, swelling test with different
    pH for swelling behaviour and thermogravimetric analysis (TGA) for thermal stability. The presence of C=N stretching
    group in the FTIR spectrum for gelatin/CNC hydrogel indicated that the cross-linking reaction between gelatin monomer
    had been successfully carried out. The hydrogel showed impressive pH sensitivity and maximum swelling was obtained
    at pH3. The TGA results clearly showed that the incorporation of CNC into gelatin was able to produce hydrogel with
    higher thermal stability compare to neat gelatin.
    Matched MeSH terms: Nanoparticles
  4. Zhang MW, Yeoh FY, Du Y, Lin KA
    Sci Total Environ, 2019 Aug 15;678:466-475.
    PMID: 31077925 DOI: 10.1016/j.scitotenv.2019.04.295
    As methyltheobromine (MTB) has been increasingly detected in wastewater, it would be necessary to develop more intensive and effective approaches to remove MTB. As Co species immobilized on carbonaceous materials appears as a promising catalyst, doping carbon with nitrogen has been also validated to significantly enhance catalytic activities for Oxone activation. Therefore, it is desired to develop a composite of immobilizing Co species on N-doped carbonaceous supports for activating Oxone to degrade MTB. Unfortunately, very few studies have demonstrated such composites for activating Oxone to degrade MTB as this type of composites are conventionally prepared via complex procedures. Alternatively, this study aims to develop such a composite conveniently by using a cobaltic coordination polymer (CP) as a precursor. Specifically Co2+ and 4,4-bipyridine (BIPY) are selected for formulating a special one-dimensional CP, which is then carbonized to convert Co to Co nanoparticles (NPs) and transform BIPY to carbon nitride (CN) matrices. Because of 1-D coordinated structure of CoBIPY, the resulting magnetic Co NPs are well-distributed and protected within CN to form a magnetic Co-embedded carbon nitride composite (MCoCN). In comparison to pristine CN and Co3O4, MCoCN exhibits much higher catalytic activities to activate Oxone for degrading MTB completely within 7 min. MCoCN also shows a much lower activation energy of 24.6 kJ/mol than other reported catalysts for activating Oxone to degrade MTB. The findings of this study validate that the 1-D coordination polymer of CoBIPY is a useful precursor to prepare MCoCN for effectively activating Oxone to degrade MTB.
    Matched MeSH terms: Nanoparticles
  5. Nur Husna Md. Yusoff, Md. Jashim Uddin, Ahmad Izani Md. Ismail
    Sains Malaysiana, 2014;43:151-159.
    A combined similarity-numerical solution of the magnetohydrodynamic boundary layer slip flow of an electrically conducting non-Newtonian power-law nanofluid along a heated radiating moving vertical plate is explored. Our nanofluid model incorporates the influences of the thermophoresis and the Brownian motion. The basic transport equations are made dimensionless first and then suitable similarity transformations are applied to reduce them into a set of nonlinear ordinary differential equations with the associated boundary conditions. The reduced equations are then solved numerically. Graphical results for the non-dimensional flow velocity, the temperature and the nanoparticles volume fraction profiles as well as for the friction factor, the local Nusselt and the Sherwood numbers are exhibited and examined for various values of the controlling parameters to display the interesting aspects of the solutions. It was found that the friction factor increases with the increase of the magnetic field (M), whilst it is decreased with the linear momentum slip parameter (a). The linear momentum slip parameter (a) reduces the heat transfer rates and the nanoparticles volume fraction rates. Our results are compatible with the existing results for a special case.
    Matched MeSH terms: Nanoparticles
  6. An'amt M, Huang N, Radiman S, Lim H, Muhamad M
    Sains Malaysiana, 2014;43:137-144.
    Titanate nanotubes were prepared by a rapid hydrothermal method in the presence of triethanolamine (TEA) using TiO2 nanoparticles as a precursor. The addition of TEA significantly reduced the formation time of the titanate nanotubes from 24 to 6 h. The crystalline structure of the titanate nanotubes was revealed to be H2Ti2O5 through the X-ray diffraction (xRD) measurement. The morphology of the titanate nanotubes was confirmed using transmission electron microscopy (TEM) while the surface area was characterized using Brunauer-Emmett-Teller (BET) surface area analysis. The titanate nanotubes produced were several hundred nanometers in length and had an average outer diameter of - 11.5 nm, inner diameter of -5.0 nm, interlayer spacing of 0.93 nm and surface area of >250 m2Ig. The photocatalytic activity of the titanate nanotubes was studied using methylene blue as a model dye; the titanate nanotubes showed better photocatalytic performance as compared to TiO2 nanoparticles.
    Matched MeSH terms: Nanoparticles
  7. Ibrahim IR, Matori KA, Ismail I, Awang Z, Rusly SNA, Nazlan R, et al.
    Sci Rep, 2020 Feb 21;10(1):3135.
    PMID: 32081972 DOI: 10.1038/s41598-020-60107-1
    Microwave absorption properties were systematically studied for double-layer carbon black/epoxy resin (CB) and Ni0.6Zn0.4Fe2O4/epoxy resin (F) nanocomposites in the frequency range of 8 to 18 GHz. The Ni0.6Zn0.4Fe2O4 nanoparticles were synthesized via high energy ball milling with subsequent sintering while carbon black was commercially purchased. The materials were later incorporated into epoxy resin to fabricate double-layer composite structures with total thicknesses of 2 and 3 mm. The CB1/F1, in which carbon black as matching and ferrite as absorbing layer with each thickness of 1 mm, showed the highest microwave absorption of more than 99.9%, with minimum reflection loss of -33.8 dB but with an absorption bandwidth of only 2.7 GHz. Double layer absorbers with F1/CB1(ferrite as matching and carbon black as absorbing layer with each thickness of 1 mm) structure showed the best microwave absorption performance in which more than 99% microwave energy were absorbed, with promising minimum reflection loss of -24.0 dB, along with a wider bandwidth of 4.8 GHz and yet with a reduced thickness of only 2 mm.
    Matched MeSH terms: Nanoparticles
  8. Aziz R, Hashim I, Abbasbandy S
    Sains Malaysiana, 2018;47:1599-1605.
    This study analyzes the heat transfer of a thin film flow on an unsteady stretching sheet in nanofluids. Three different types of nanoparticles are considered; copper Cu, alumina Al2O3 and titania TiO2 with water as the base fluid. The governing equations are simplified using similarity transformations. The resulting coupled nonlinear differential equations are solved by the Homotopy Analysis Method (HAM). The analytical series solutions are presented and the numerical results obtained are tabulated. In particular, it shows that the heat transfer rate decreases when nanoparticles volume fraction increases.
    Matched MeSH terms: Nanoparticles
  9. Rabiatul Basria S.M.N. Mydin, Izzah Nadhirah Muhamad Zahidi, Nurul Nadiah Ishak, Nik Shaida Shamim Nik Ghazali, Said Moshawih, Shafiquzzaman Siddiquee
    MyJurnal
    The application of nanoparticles (NPs) has attracted considerable attention as targeted delivery systems. CaCO3 has become the focus due to its advantages including affordability, low toxicity, biocompatibility, cytocompatibility, pH sensitivity and sedate biodegradability and environment friendly materials. In this article, we will discuss the po- tential roles of CaCO3-NPs in three major therapeutic applications; as antimicrobial, for drug delivery, and as gene delivery nanocarrier.
    Matched MeSH terms: Nanoparticles
  10. Nazir MH, Khan ZA, Saeed A, Bakolas V, Braun W, Bajwa R, et al.
    Materials (Basel), 2017 Oct 25;10(11).
    PMID: 29068395 DOI: 10.3390/ma10111225
    A study has been presented on the effects of intrinsic mechanical parameters, such as surface stress, surface elastic modulus, surface porosity, permeability and grain size on the corrosion failure of nanocomposite coatings. A set of mechano-electrochemical equations was developed by combining the popular Butler-Volmer and Duhem expressions to analyze the direct influence of mechanical parameters on the electrochemical reactions in nanocomposite coatings. Nanocomposite coatings of Ni with Al₂O₃, SiC, ZrO₂ and Graphene nanoparticles were studied as examples. The predictions showed that the corrosion rate of the nanocoatings increased with increasing grain size due to increase in surface stress, surface porosity and permeability of nanocoatings. A detailed experimental study was performed in which the nanocomposite coatings were subjected to an accelerated corrosion testing. The experimental results helped to develop and validate the equations by qualitative comparison between the experimental and predicted results showing good agreement between the two.
    Matched MeSH terms: Nanoparticles
  11. AlMatar M, Makky EA, Var I, Koksal F
    Curr Drug Deliv, 2018;15(4):470-484.
    PMID: 29219055 DOI: 10.2174/1567201815666171207163504
    BACKGROUND: Until recently, one of the main reasons for mortality has been infectious diseases, and bacteria that are drug-resistant have emerged as a result of the wide application, as well as the misuse of antibacterial medications. Having multidrug-resistance, bacteria present a great problem for the efficient management of bacterial infections and this challenge has resulted in the creation of other means of dealing with bacterial diseases. Of late, metallic nanoparticles (NPs), employed as antibacterial agents, have the potential for use against resistance to bacterial drugs.

    OBJECTIVE: The mechanisms of bacterial resistance are described in this review and this is followed by an outline of the features and uses of metallic NPs as antibiotic agents to address bacteria that are antibiotic- sensitive and resistant. Additionally, a general impression of metallic NPs as antibiofilm bactericidal agents is presented.

    CONCLUSION: Biofilms and bacterial strains that are resistant to antibiotics present a grave public health challenge and this has enhanced the need to develop new bactericidal agents. Therefore, nanomaterials are considered as a potential platform for managing bacterial infections.

    Matched MeSH terms: Metal Nanoparticles/administration & dosage*; Metal Nanoparticles/adverse effects; Metal Nanoparticles/therapeutic use*
  12. Mazlan SZ, Lee YH, Hanifah SA
    Sensors (Basel), 2017 Dec 09;17(12).
    PMID: 29232842 DOI: 10.3390/s17122859
    Laccase enzyme, a commonly used enzyme for the construction of biosensors for phenolic compounds was used for the first time to develop a new biosensor for the determination of the azo-dye tartrazine. The electrochemical biosensor was based on the immobilization of laccase on functionalized methacrylate-acrylate microspheres. The biosensor membrane is a composite of the laccase conjugated microspheres and gold nanoparticles (AuNPs) coated on a carbon-paste screen-printed electrode. The reaction involving tartrazine can be catalyzed by laccase enzyme, where the current change was measured by differential pulse voltammetry (DPV) at 1.1 V. The anodic peak current was linear within the tartrazine concentration range of 0.2 to 14 μM (R² = 0.979) and the detection limit was 0.04 μM. Common food ingredients or additives such as glucose, sucrose, ascorbic acid, phenol and sunset yellow did not interfere with the biosensor response. Furthermore, the biosensor response was stable up to 30 days of storage period at 4 °C. Foods and beverage were used as real samples for the biosensor validation. The biosensor response to tartrazine showed no significant difference with a standard HPLC method for tartrazine analysis.
    Matched MeSH terms: Metal Nanoparticles
  13. Lee CY, Ooi IH
    PMID: 27618068 DOI: 10.3390/ph9030054
    Temozolomide (TMZ) is one of the most effective chemotherapeutic agents for glioblastoma multiforme, but the required high administration dose is accompanied by side effects. To overcome this problem and to further improve TMZ's efficacy, targeted delivery of TMZ by using polymeric nanoparticles has been explored. We synthesised the PLGA-PEG-FOL copolymer and attempted encapsulation of TMZ into PLGA-PEG-FOL nanoparticles using the emulsion solvent evaporation method and the nanoprecipitation method. Conjugation of PEG and FOL to PLGA has been reported to be able to increase the delivery of TMZ to the brain as well as targeting the glioma cells. However, despite making numerous modifications to these methods, the loading of TMZ in the nanoparticles only ranged between 0.2% and 2%, and the nanoparticles were between 400 nm and 600 nm in size after freeze-drying. We proceed with determining the release profile of TMZ in phosphate buffered saline (PBS). Our initial data indicated that TMZ was slowly released from the nanoparticles. The metabolite of TMZ rather than the parent compound was detected in PBS. Our study suggests that while PLGA-PEG-FOL can be used as a polymeric or encapsulation material for central delivery of TMZ, a practical and cost effective formulation method is still far from reach.
    Matched MeSH terms: Nanoparticles
  14. Alsabery AI, Chamkha AJ, Saleh H, Hashim I
    Sci Rep, 2017 05 24;7(1):2357.
    PMID: 28539585 DOI: 10.1038/s41598-017-02241-x
    This work analyses free convection flow of a nanofluid in an inclined square enclosure consisting of a porous layer and a nanofluid layer using the finite difference methodology. Sinusoidal temperature boundary conditions are imposed on the two opposing vertical walls. Nanofluids with water as base and Ag or Cu or Al2O3 or TiO2 nanoparticles are considered for the problem. The related parameters of this study are the Darcy number, nanoparticle volume fraction, phase deviation, amplitude ratio, porous layer thickness and the inclination angle of the cavity. A comparison with previously published work is performed and the results are in good agreement. Detailed numerical data for the fluid flow and thermal distributions inside the square enclosure, and the Nusselt numbers are presented. The obtained results show that the heat transfer is considerably affected by the porous layer increment. Several nanoparticles depicted a diversity improvement on the convection heat transfer.
    Matched MeSH terms: Nanoparticles
  15. Zhang Y, Knibbe R, Sunarso J, Zhong Y, Zhou W, Shao Z, et al.
    Adv Mater, 2017 Dec;29(48).
    PMID: 28628239 DOI: 10.1002/adma.201700132
    Solid-oxide fuel cells (SOFCs) are electricity generators that can convert the chemical energy in various fuels directly to the electric power with high efficiency. Recent advances in materials and related key components for SOFCs operating at ≈500 °C are summarized here, with a focus on the materials, structures, and techniques development for low-temperature SOFCs, including the analysis of most of the critical parameters affecting the electrochemical performance of the electrolyte, anode, and cathode. New strategies, such as thin-film deposition, exsolution of nanoparticles from perovskites, microwave plasma heating, and finger-like channeled electrodes, are discussed. These recent developments highlight the need for electrodes with higher activity and electrolytes with greater conductivity to generate a high electrochemical performance at lower temperatures.
    Matched MeSH terms: Nanoparticles
  16. Adamu Ahmad K, Sabo Mohammed A, Abas F
    Molecules, 2016 Mar 14;21(3):256.
    PMID: 26985885 DOI: 10.3390/molecules21030256
    The use of chitosan as a delivery carrier has attracted much attention in recent years. In this study, chitosan nanoparticles (CS-NP) and chitosan-ΦKAZ14 bacteriophage-loaded nanoparticles (C-ΦKAZ14 NP) were prepared by a simple coercavation method and characterized. The objective was to achieve an effective protection of bacteriophage from gastric acids and enzymes in the chicken gastrointestinal tract. The average particle sizes for CS-NP and C-ΦKAZ14 NP were 188 ± 7.4 and 176 ± 3.2 nm, respectively. The zeta potentials for CS-NP and C-ΦKAZ14 NP were 50 and 60 mV, respectively. Differential scanning calorimetry (DSC) of C-ΦKAZ14 NP gave an onset temperature of -17.17 °C with a peak at 17.32 °C and final end set of 17.41 °C, while blank chitosan NP had an onset of -20.00 °C with a peak at -19.78 °C and final end set at -20.47. FT-IR spectroscopy data of both CS-NP and C-ΦKAZ14 NP were the same. Chitosan nanoparticles showed considerable protection of ΦKAZ14 bacteriophage against degradation by enzymes as evidenced in gel electrophoresis, whereby ΦKAZ14 bacteriophage encapsulated in chitosan nanoparticles were protected whereas the naked ΦKAZ14 bacteriophage were degraded. C-ΦKAZ14 NP was non-toxic as shown by a chorioallantoic membrane (CAM) toxicity assay. It was concluded that chitosan nanoparticles could be a potent carrier of ΦKAZ14 bacteriophage for oral therapy against colibacillosis in poultry.
    Matched MeSH terms: Nanoparticles/administration & dosage*; Nanoparticles/ultrastructure; Nanoparticles/chemistry
  17. Mie R, Samsudin MW, Din LB, Ahmad A, Ibrahim N, Adnan SN
    Int J Nanomedicine, 2014;9:121-7.
    PMID: 24379670 DOI: 10.2147/IJN.S52306
    Development of a green chemistry process for the synthesis of silver nanoparticles has become a focus of interest. This would offer numerous benefits, including ecofriendliness and compatibility for biomedical applications. Here we report the synthesis of silver nanoparticles from the reduction of silver nitrate and an aqueous extract of the lichen Parmotrema praesorediosum as a reductant as well as a stabilizer. The physical appearance of these silver nanoparticles was characterized using ultraviolet-visible spectroscopy, electron microscopy, energy-dispersive spectroscopy, and X-ray diffraction techniques. The results show that silver nanoparticles synthesized using P. praesorediosum have an average particle size of 19 nm with a cubic structure. The antibacterial activity of the synthesized silver nanoparticles was tested against eight micro-organisms using the disk diffusion method. The results reveal that silver nanoparticles synthesized using P. praesorediosum have potential antibacterial activity against Gram-negative bacteria.
    Matched MeSH terms: Metal Nanoparticles/administration & dosage*; Metal Nanoparticles/ultrastructure; Metal Nanoparticles/chemistry*
  18. Sajahan NA, Wan Ibrahim WM
    ScientificWorldJournal, 2014;2014:275984.
    PMID: 25383364 DOI: 10.1155/2014/275984
    Due to similarity in composition to the mineral component of bones and human hard tissues, hydroxyapatite with chemical formula Ca10(PO4)6(OH)2 has been widely used in medical field. Both chicken and duck eggshells are mainly composed of calcium carbonate. An attempt has been made to fabricate nanohydroxyapatite (nHA) by chicken (CES) and duck eggshells (DES) as calcium carbonate source (CaCO3). CES and DES were reacted with diammonium hydrogen [(NH4)2HPO4] solution and subjected to microwave heating at 15 mins. Under the effect of microwave irradiation, nHA was produced directly in the solution and involved in crystallographic transformation. Sample characterization was done using by X-ray diffraction (XRD), fourier transform infrared spectroscopy (FTIR), and scanning electron microscopy (SEM).
    Matched MeSH terms: Nanoparticles/ultrastructure; Nanoparticles/chemistry
  19. Ramimoghadam D, Bagheri S, Abd Hamid SB
    Biomed Res Int, 2014;2014:205636.
    PMID: 25126547 DOI: 10.1155/2014/205636
    Anatase titanium dioxide nanoparticles (TiO2-NPs) were synthesized by sol-gel method using rice straw as a soft biotemplate. Rice straw, as a lignocellulosic waste material, is a biomass feedstock which is globally produced in high rate and could be utilized in an innovative approach to manufacture a value-added product. Rice straw as a reliable biotemplate has been used in the sol-gel method to synthesize ultrasmall sizes of TiO2-NPs with high potential application in photocatalysis. The physicochemical properties of titanium dioxide nanoparticles were investigated by a number of techniques such as X-ray diffraction analysis (XRD), transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FTIR), Raman spectroscopy, thermogravimetric analysis (TGA), ultraviolet visible spectra (UV-Vis), and surface area and pore size analysis. All results consensually confirmed that particle sizes of synthesized titanium dioxide were template-dependent, representing decrease in the nanoparticles sizes with increase of biotemplate concentration. Titanium dioxide nanoparticles as small as 13.0 ± 3.3 nm were obtained under our experimental conditions. Additionally, surface area and porosity of synthesized TiO2-NPs have been enhanced by increasing rice straw amount which results in surface modification of nanoparticles and potential application in photocatalysis.
    Matched MeSH terms: Metal Nanoparticles/ultrastructure; Metal Nanoparticles/chemistry*
  20. Lee HV, Hamid SB, Zain SK
    ScientificWorldJournal, 2014;2014:631013.
    PMID: 25247208 DOI: 10.1155/2014/631013
    Lignocellulosic biomass is a complex biopolymer that is primary composed of cellulose, hemicellulose, and lignin. The presence of cellulose in biomass is able to depolymerise into nanodimension biomaterial, with exceptional mechanical properties for biocomposites, pharmaceutical carriers, and electronic substrate's application. However, the entangled biomass ultrastructure consists of inherent properties, such as strong lignin layers, low cellulose accessibility to chemicals, and high cellulose crystallinity, which inhibit the digestibility of the biomass for cellulose extraction. This situation offers both challenges and promises for the biomass biorefinery development to utilize the cellulose from lignocellulosic biomass. Thus, multistep biorefinery processes are necessary to ensure the deconstruction of noncellulosic content in lignocellulosic biomass, while maintaining cellulose product for further hydrolysis into nanocellulose material. In this review, we discuss the molecular structure basis for biomass recalcitrance, reengineering process of lignocellulosic biomass into nanocellulose via chemical, and novel catalytic approaches. Furthermore, review on catalyst design to overcome key barriers regarding the natural resistance of biomass will be presented herein.
    Matched MeSH terms: Nanoparticles/metabolism; Nanoparticles/chemistry*
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