Displaying publications 61 - 80 of 379 in total

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  1. Lau, K.T., Kok, S.L., Razak, J.A., Munawar, R.F.
    MyJurnal
    Piezoelectric poly(vinyliden fluoride) (PVDF) is attractive because of their low cost, lightweight, biocompatibility and superior mechanical flexibility. Electrophoretic deposition (EPD) technique has the capability of conformally deposit PVDF film on uneven surface target. Nevertheless, knowledge of the role of dispersion formulating process is crucial for achieving an even and uniform PVDF film. Sedimentation test showed PVDF polymer dispersions are more stable and well-dispersed in DMF than in MEK media. For MEK-based dispersion, higher stirring temperature produced less stable and more agglomerated PVDF dispersion, whereas longer stirring time reduced the degree of the PVDF polymer agglomeration. More stable DMF-based dispersions produced lower PVDF depositions than the less stable MEK-based dispersions. PVDF dispersions with higher degree of agglomeration produced films with higher surface roughness and porosity feature.
    Matched MeSH terms: Porosity
  2. Yam F, Hassan Z, Omar K
    This article reports on the studies of structural and optical properties of nanoporous GaN prepared by Pt assisted electro chemical etching. The porous GaN samples were investigated by scanning electron microscopy (SEM), atomic force microscopy (AFM), and optical transmission (OT). SEM images liang indicated that the density of the pores increased with etching duration, however, the etching duration has no significant effect on the size and shape of the pores. AFM measurements exhibited that the surface roughness was increased with etching durations, however, for long etching duration, the increase of the surface roughness became insignificant. OT measurements revealed that the increase of pore density would lead to the reduction of light transmission. The studies showed that the porosity could influence the structural and optical properties of the GaN.
    Matched MeSH terms: Porosity
  3. Mohammed Salisu Musa, Mohd Marsin Sanagi, Wan Aini Wan Ibrahim, Hadi Nur
    Sains Malaysiana, 2015;44:613-618.
    Carbon spheres (CSs) were synthesized from sucrose by hydrothermal reaction. The synthesized materials were further
    activated with potassium hydroxide (KOH) at different concentrations. The effects of KOH concentration on the surface area
    and morphology were investigated. The route for pore formation and structural deformation in carbon spheres during
    activation has been proposed and discussed based on micrographs and porosity trends. It was suggested that the pore
    formation and structural deformation phenomena were due to the intercalating power of energized K+ into the carbon.
    This work provides an insight of the pore formation in carbon spheres for the development of adsorbents as well as for
    the understanding of the structural deformation of such materials at higher KOH concentrations.
    Matched MeSH terms: Porosity
  4. Mohammad Hafizuddin Jumali, Norhashimah Ramli, Izura Izzuddin, Muhammad Yahaya, Muhamad Mat Salleh
    The influence of PANI additions on methanol sensing properties of ZnO thin films at room temperature had been investigated. Commercial polyaniline powder (PANI) was mixed into 3 mL ZnO solution in five different weight percentages namely 1.25, 2.50, 3.75, 5.00 and 6.25% to obtain ZnO/PANI composite solutions. These solutions were spin coated onto glass substrate to form thin films. Microstructural studies by FESEM indicated that ZnO/PANI films showed porous structures with nanosize grains. The thickness of the film increased from 55 to 256 nm, proportionate to increment of PANI. The presence of 2 adsorption peaks at ~310 nm and ~610 nm in UV-Vis spectrum proved that addition of PANI has modified the adsorption peak of ZnO film. Methanol vapour detection showed that addition of PANI into ZnO dramatically improved the sensing properties of the sensor. The sensors also exhibited good repeatability and reversibility. Sensor with the amount of PANI of 3.75 wt% exhibited the highest sensitivity with response and recovery time was about 10 and 80 s, respectively. The possible sensing mechanism of the sensor was also discussed in this article.
    Matched MeSH terms: Porosity
  5. 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: Porosity
  6. Mehmood OU, Norzie Mustapha, Sharidan Shafie, Hayat T
    Sains Malaysiana, 2014;43:1109-1118.
    This research looks at the effects of partial slip on heat and mass transfer of peristaltic transport. The magnetohydrodynamic (MHD) flow of viscous fluid in a porous asymmetric channel has been considered. The exact solutions for the stream function, longitudinal pressure gradient, longitudinal velocity, shear stress, temperature and concentration fields are derived by adopting long wavelength and small Reynolds number approximations. The results showed that peristaltic pumping and trapping are reduced with increasing velocity slip parameter. Furthermore, temperature increases with increasing thermal slip parameter. Moreover, the concentration profile decreases with increasing porosity parameter, Schmidt number and concentration slip parameter. Comparisons with published results are found to be in good agreement.
    Matched MeSH terms: Porosity
  7. Mohd. Reusmaazran Yusof, Roslinda Shamsudin, Syafiq Baharuddin, Idris Besar
    Sains Malaysiana, 2008;37:233-237.
    Porous hydroxyapatite (HAp) as a bone graft substitute was produced via gas technique with three different concentrations of hydrogen peroxide (H2O2) namely 20, 30 and 50%. Hydroxyapatite(HA) slurries with different concentration were produced by mixing between H2O2 solutions and HA powder (L/P) with different ratio i.e. 0.9 to 2.20 ml.g-1. Different L/P ratio and H2O2 concentration affected the porosity, interconnectivity and compressive strength of HAp sample. Changes in L/P ratio between 0.9 to 2.20 ml.g-1, increases the porosity around 50 - 65% at 20% H2O2 concentration. Porosity increases with the L/P values and H2O2 concentration which 76% of porosity was obtained at 50% H2O2 and 2.20 mlg-1 of L/P. The compressive strength of HAp is in the range of 0.5 to 2.15 MPa and is found decreasing with the increasing of L/P values.
    Matched MeSH terms: Porosity
  8. Miah MJ, Ali MK, Paul SC, John Babafemi A, Kong SY, Šavija B
    Materials (Basel), 2020 Mar 05;13(5).
    PMID: 32151088 DOI: 10.3390/ma13051168
    This study evaluates the mechanical, durability, and residual compressive strength (after being exposed to 20, 120, 250, 400 and 600 °C) of mortar that uses recycled iron powder (RIP) as a fine aggregate. Within this context, mechanical strength, shrinkage, durability, and residual strength tests were performed on mortar made with seven different percentages (0%, 5%, 10%, 15%, 20%, 30% and 50%) of replacement of natural sand (NS) by RIP. It was found that the mechanical strength of mortar increased when replaced with up to 30% NS by RIP. In addition, the increase was 30% for compressive, 18% for tensile, and 47% for flexural strength at 28 days, respectively, compared to the reference mortar (mortar made with 100% NS). Shrinkage was observed for the mortar made with 100% NS, while both shrinkage and expansion occurred in the mortar made with RIP, especially for RIP higher than 5%. Furthermore, significantly lower porosity and capillary water absorption were observed for mortar made with up to 30% RIP, compared to that made with 100% NS, which decreased by 36% for porosity and 48% for water absorption. As the temperature increased, the strength decreased for all mixes, and the drop was more pronounced for the temperatures above 250 °C and 50% RIP. This study demonstrates that up to 30% RIP can be utilized as a fine aggregate in mortar due to its better mechanical and durability performances.
    Matched MeSH terms: Porosity
  9. Rizal S, Fizree HM, Hossain MS, Ikramullah, Gopakumar DA, Wan Ni EC, et al.
    Heliyon, 2020 Mar;6(3):e03550.
    PMID: 32190763 DOI: 10.1016/j.heliyon.2020.e03550
    This study was conducted to determine the influence of the oil palm boiler ash (OPBA) reinforcement on the microstructural, physical, mechanical and thermal properties of epoxy polymer composites. The chemical composition analysis of OPBA revealed that it contains about 55 wt.% of SiO2 along with other metallic oxides and elements. The surface morphology of OPBA showed angular and irregular shapes with porous structures. The influence of OPBA as a reinforcement in epoxy composite was studied with varying filler loadings (10-50 wt.%) and different particle sizes (50-150 μm). The result showed that the incorporation of OPBA in composites has improved the physical, mechanical and thermal properties of the epoxy matrix. The highest physical and mechanical properties of fabricated composites were attained with 30 wt.% loading and size of 50 μm. Also, thermal stability and the percentage of char residue of the composite increased with increasing filler loading. Furthermore, the contact angle of OPBA reinforced epoxy composites increased with the increase of filler loading. The lowest value of the contact angle was obtained at 30 wt.% of filler loading with the OPBA particle size of 50 μm. The finding of this study reveals that the OPBA has the potential to be used as reinforcement or filler as well as an alternative of silica-based inorganic fillers used in the enhancement of mechanical, physical and thermal properties of the epoxy polymer composite.
    Matched MeSH terms: Porosity
  10. Ghanbari T, Abnisa F, Wan Daud WMA
    Sci Total Environ, 2020 Mar 10;707:135090.
    PMID: 31863992 DOI: 10.1016/j.scitotenv.2019.135090
    The environment sustenance and preservation of global climate are known as the crucial issues of the world today. Currently, the crisis of global warming due to CO2 emission has turned into a paramount concern. To address such a concern, diverse CO2 capture and sequestration techniques (CCS) have been introduced so far. In line with this, Metal Organic Frameworks (MOFs) have been considered as the newest and most promising material for CO2 adsorption and separation. Due to their outstanding properties, this new class of porous materials a have exhibited a conspicuous potential for gas separation technologies especially for CO2 storage and separation. Thus, the present review paper is aimed to discuss the adsorption properties of CO2 on the MOFs based on the adsorption mechanisms and the design of the MOF structures. In addition, the main challenge associated with using this prominent porous material has been mentioned.
    Matched MeSH terms: Porosity
  11. 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: Porosity
  12. 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: Porosity
  13. Syahrom A, Abdul Kadir MR, Abdullah J, Öchsner A
    Med Eng Phys, 2013 Jun;35(6):792-9.
    PMID: 22959618 DOI: 10.1016/j.medengphy.2012.08.011
    In the development of artificial cancellous bones, two major factors need to be considered: the integrity of the overall structure and its permeability. Whilst there have been many studies analysing the mechanical properties of artificial and natural cancellous bones, permeability studies, especially those using numerical simulation, are scarce. In this study, idealised cancellous bones were simulated from the morphological indices of natural cancellous bone. Three different orientations were also simulated to compare the anisotropic nature of the structure. Computational fluid dynamics methods were used to analyse fluid flow through the cancellous structures. A constant mass flow rate was used to determine the intrinsic permeability of the virtual specimens. The results showed similar permeability of the prismatic plate-and-rod model to the natural cancellous bone. The tetrakaidecahedral rod model had the highest permeability under simulated blood flow conditions, but the plate counterpart had the lowest. Analyses on the anisotropy of the virtual specimens showed the highest permeability for the horizontal orientation. Linear relationships were found between permeability and the two physical properties, porosity and bone surface area.
    Matched MeSH terms: Porosity
  14. Mustafa NWNA, Ahmad R, Ahmad Khushaini MA, Kamar Affendi NH, Ab Ghani SM, Tan SK, et al.
    ACS Biomater Sci Eng, 2024 Jan 08;10(1):405-419.
    PMID: 38040671 DOI: 10.1021/acsbiomaterials.3c01551
    This study assessed the corrosion resistance, intracutaneous reactivity, acute systemic toxicity, and in situ tissue effect of the implantation of porous NiTi fabricated by metal injection molding in animal models. For the intracutaneous reactivity study, five intracutaneous injections were administered per site with and without the tested extract in polar and nonpolar solutions. The extract was also delivered via intravenous and intraperitoneal routes for acute systemic toxicity. TiAl6 V4 (control) and porous NiTi were implanted in rabbit femora for a period of 13 weeks to evaluate the in situ tissue response. Corrosion was evaluated through open and cyclic polarization in PBS, while biocompatibility was investigated by assessing the general conditions, skin irritation score (edema and erythema), and histopathology. No active dissolution or hysteresis loop was observed in the corrosion study. None of the animals exhibited death, moribundity, impending death, severe pain, self-mutilation, or overgrooming. No edema was observed at injection sites. Only the positive control showed an erythematous reaction at 24, 48, and 72 h observations (p < 0.001). Porous NiTi showed a low in situ biological response for inflammation, neovascularization, and fibrosis in comparison to the control implant (p = 0.247, 0.005, and 0.011, respectively). Porous NiTi also demonstrated high pitting corrosion resistance while causing no acute hypersensitivity or acute systemic toxicity. The study concludes that porous NiTi implants were unlikely to cause local sensitization, acute systemic toxicity, or chronic inflammatory reactions in an animal model. Porous NiTi also exhibited osseointegration equivalent to Ti6AI4 V of known biocompatibility.
    Matched MeSH terms: Porosity
  15. Xiong J, Luo R, Jia Z, Ge S, Lam SS, Xie L, et al.
    Int J Biol Macromol, 2024 Jan;256(Pt 2):128399.
    PMID: 38007014 DOI: 10.1016/j.ijbiomac.2023.128399
    To develop a green and facile adsorbent for removing indoor polluted formaldehyde (HCHO) gas, the biomass porous nanofibrous membranes (BPNMs) derived from microcrystalline cellulose/chitosan were fabricated by electrospinning. The enhanced chemical adsorption sites with diverse oxygen (O) and nitrogen (N)-containing functional groups were introduced on the surface of BPNMs by non-thermal plasma modification under carbon dioxide (CO2) and nitrogen (N2) atmospheres. The average nanofiber diameters of nanofibrous membranes and their nanomechanical elastic modulus and hardness values decreased from 341 nm to 175-317 nm and from 2.00 GPa and 0.25 GPa to 1.70 GPa and 0.21 GPa, respectively, after plasma activation. The plasma-activated nanofibers showed superior hydrophilicity (WCA = 0°) and higher crystallinity than that of the control. The optimal HCHO adsorption capacity (134.16 mg g-1) of BPNMs was achieved under a N2 atmosphere at a plasma power of 30 W and for 3 min, which was 62.42 % higher compared with the control. Pyrrolic N, pyridinic N, CO and O-C=O were the most significant O and N-containing functional groups for the improved chemical adsorption of the BPNMs. The adsorption mechanism involved a synergistic combination of physical and chemical adsorption. This study provides a novel strategy that combines clean plasma activation with electrospinning to efficiently remove gaseous HCHO.
    Matched MeSH terms: Porosity
  16. Zakaria DS, Rozi SKM, Halim HNA, Mohamad S, Zheng GK
    Environ Sci Pollut Res Int, 2024 Mar;31(11):16309-16327.
    PMID: 38315341 DOI: 10.1007/s11356-024-32285-2
    Climate change caused by the greenhouse gases CO2 remains a topic of global concern. To mitigate the excessive levels of anthrophonic CO2 in the atmosphere, CO2 capture methods have been developed and among these, adsorption is an especially promising method. This paper presents a series of amine functionalized biochar obtained from desiccated coconut waste (amine-biochar@DCW) for use as CO2 adsorbent. They are ethylenediamine-functionalized biochar@DCW (EDA-biochar@DCW), diethylenetriamine-functionalized biochar@DCW (DETA-biochar@DCW), triethylenetetramine-functionalized biochar@DCW (TETA-biochar@DCW), tetraethylenepentamine-functionalized biochar@DCW (TEPA-biochar@DCW), and pentaethylenehexamine-functionalized biochar@DCW (PEHA-biochar@DCW). The adsorbents were obtained through amine functionalization of biochar and they are characterized using Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), energy dispersive X-ray (EDX) spectroscopy, Brunauer-Emmett-Teller (BET), and thermogravimetric analysis (TGA). The CO2 adsorption study was conducted isothermally and using a thermogravimetric analyzer. From the results of the characterization analyses, a series of amine-biochar@DCW adsorbents had larger specific surface area in the range of 16.2 m2/g-37.1 m2/g as compare to surface area of pristine DCW (1.34 m2/g). Furthermore, the results showed an increase in C and N contents as well as the appearance of NH stretching, NH bending, CN stretching, and CN bending, suggesting the presence of amine on the surface of biochar@DCW. The CO2 adsorption experiment shows that among the amine modified biochar adsorbents, TETA-biochar@DCW has the highest CO2 adsorption capacity (61.78 mg/g) when using a mass ratio (m:m) of biochar@DCW:TETA (1:2). The adsorption kinetics on the TETA-biochar@DCW was best fitted by the pseudo-second model (R2 = 0.9998), suggesting the adsorption process occurs through chemisorption. Additionally, TETA-biochar@DCW was found to have high selectivity toward CO2 gas and good reusability even after five CO2 adsorption-desorption cycles. The results demonstrate the potential of novel CO2 adsorbents based on amine functionalized on desiccated coconut waste biochar.
    Matched MeSH terms: Porosity
  17. Md Yusop AH, Wan Ali WFF, Jamaludin FH, Szali Januddi F, Sarian MN, Saad N, et al.
    Biotechnol J, 2024 Mar;19(3):e2300464.
    PMID: 38509814 DOI: 10.1002/biot.202300464
    The present study evaluates the corrosion behavior of poly[xylitol-(1,12-dodecanedioate)](PXDD)-HA coated porous iron (PXDD140/HA-Fe) and its cell-material interaction aimed for temporary bone scaffold applications. The physicochemical analyses show that the addition of 20 wt.% HA into the PXDD polymers leads to a higher crystallinity and lower surface roughness. The corrosion assessments of the PXDD140/HA-Fe evaluated by electrochemical methods and surface chemistry analysis indicate that HA decelerates Fe corrosion due to a lower hydrolysis rate following lower PXDD content and being more crystalline. The cell viability and cell death mode evaluations of the PXDD140/HA-Fe exhibit favorable biocompatibility as compared to bare Fe and PXDD-Fe scaffolds owing to HA's bioactive properties. Thus, the PXDD140/HA-Fe scaffolds possess the potential to be used as a biodegradable bone implant.
    Matched MeSH terms: Porosity
  18. Aaiza G, Khan I, Shafie S
    Nanoscale Res Lett, 2015 Dec;10(1):490.
    PMID: 26698873 DOI: 10.1186/s11671-015-1144-4
    Energy transfer in mixed convection unsteady magnetohydrodynamic (MHD) flow of an incompressible nanofluid inside a channel filled with saturated porous medium is investigated. The channel with non-uniform walls temperature is taken in a vertical direction under the influence of a transverse magnetic field. Based on the physical boundary conditions, three different flow situations are discussed. The problem is modelled in terms of partial differential equations with physical boundary conditions. Four different shapes of nanoparticles of equal volume fraction are used in conventional base fluids, ethylene glycol (EG) (C 2 H 6 O 2 ) and water (H 2 O). Solutions for velocity and temperature are obtained discussed graphically in various plots. It is found that viscosity and thermal conductivity are the most prominent parameters responsible for different results of velocity and temperature. Due to higher viscosity and thermal conductivity, C 2 H 6 O 2 is regarded as better convectional base fluid compared to H 2 O.
    Matched MeSH terms: Porosity
  19. Wang L, Li Y, Huang G, Zhang X, Pingguan-Murphy B, Gao B, et al.
    Crit Rev Biotechnol, 2016 Jun;36(3):553-65.
    PMID: 25641330 DOI: 10.3109/07388551.2014.993588
    Natural cellular microenvironment consists of spatiotemporal gradients of multiple physical (e.g. extracellular matrix stiffness, porosity and stress/strain) and chemical cues (e.g. morphogens), which play important roles in regulating cell behaviors including spreading, proliferation, migration, differentiation and apoptosis, especially for pathological processes such as tumor formation and progression. Therefore, it is essential to engineer cellular gradient microenvironment incorporating various gradients for the fabrication of normal and pathological tissue models in vitro. In this article, we firstly review the development of engineering cellular physical and chemical gradients with cytocompatible hydrogels in both two-dimension and three-dimension formats. We then present current advances in the application of engineered gradient microenvironments for the fabrication of disease models in vitro. Finally, concluding remarks and future perspectives for engineering cellular gradients are given.
    Matched MeSH terms: Porosity
  20. Uddin MJ, Khan WA, Amin NS
    PLoS One, 2014;9(6):e99384.
    PMID: 24927277 DOI: 10.1371/journal.pone.0099384
    The unsteady two-dimensional laminar g-Jitter mixed convective boundary layer flow of Cu-water and Al2O3-water nanofluids past a permeable stretching sheet in a Darcian porous is studied by using an implicit finite difference numerical method with quasi-linearization technique. It is assumed that the plate is subjected to velocity and thermal slip boundary conditions. We have considered temperature dependent viscosity. The governing boundary layer equations are converted into non-similar equations using suitable transformations, before being solved numerically. The transport equations have been shown to be controlled by a number of parameters including viscosity parameter, Darcy number, nanoparticle volume fraction, Prandtl number, velocity slip, thermal slip, suction/injection and mixed convection parameters. The dimensionless velocity and temperature profiles as well as friction factor and heat transfer rates are presented graphically and discussed. It is found that the velocity reduces with velocity slip parameter for both nanofluids for fluid with both constant and variable properties. It is further found that the skin friction decreases with both Darcy number and momentum slip parameter while it increases with viscosity variation parameter. The surface temperature increases as the dimensionless time increases for both nanofluids. Nusselt numbers increase with mixed convection parameter and Darcy numbers and decreases with the momentum slip. Excellent agreement is found between the numerical results of the present paper with published results.
    Matched MeSH terms: Porosity
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