Faculty of Engineering University of Malaya | University of Malaya, Malaysia (original) (raw)

Papers by Faculty of Engineering University of Malaya

Highly reactive phenolic compounds of pyrolysis bio-oil are recognized as a major cause of the un... more Highly reactive phenolic compounds of pyrolysis bio-oil are recognized as a major cause of the unpleasant properties of this biofuel. Catalytic hydrodeoxygenation of phenolic compounds of bio-oil is an efficient technique for improving the quality of bio-oil. Dual function catalysts consisting of metal and acid sites are usually used for transformation of bio-oil/bio-oil model compounds to high value hydrocarbons. Metal and acid sites are generally involved in hydrogenation/hydrodeoxygenation and dehydration/hydrocracking/dealkylation/alkylation reaction mechanisms, respectively. In this work, the product selectivity of hydrogenation of phenol, o-cresol, m-cresol and guaiacol was investigated over combined catalysts of Pd/C with zeolite solid acids of HZSM-5 (Si/Al of 30, 50 and 80) and HY (Si/Al of 30 and 60). Catalytic activity and product distribution in the hydrogenation process were affected by the density and strength of zeolite acid sites. HZSM-5 (30) with only weak acid sites showed lower cyclohexane selectivity compared with HZSM-5 (50) and HZSM-5 (80) which had both weak and strong acid sites. HY (30) and HY (60) containing only strong acid sites favored production of cycloketones.

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http://pubs.rsc.org/en/content/articlepdf/2015/ra/c5ra00367a

The material characteristics of doped SiO2 fibre are studied, the electron traps in the product m... more The material characteristics of doped SiO2 fibre are studied, the electron traps in the product medium creating a situation attractive for their application in thermoluminescence (TL) radiation dosimetry. To date, rather limited research has been conducted towards gaining an essential understanding of the magnitude of TL signal and material characteristics of doped fibres. Characterization is being sought to ensure that the mechanism of TL yield in optical fibres is well understood, allowing a favourable well controlled production situation to be established. The intended end point is to specify dosimeters, not only for clinical dosimetry but also for their application in industrial/energy-industry settings. Investigation of the surface oxidation state of the Ge-doped SiO2 optical preform has been carried out using the X-ray photoelectron spectroscopy technique. In a further development using the fibre forming technology, particle-induced X-ray emission/Rutherford back scattering measurements have been employed to ascertain dopant concentrations of Ge-doped-cladding photonic crystal fibres (PCFs) with a view to improving TL yield. Present results concern uncollapsed and collapsed-hole-PCFs.

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http://ieeexplore.ieee.org/ielx7/50/7064849/07050239.pdf?tp=&arnumber=7050239&isnumber=7064849

Deep beams are commonly used in tall buildings, offshore structures, and foundations. According t... more Deep beams are commonly used in tall buildings, offshore structures, and foundations. According to many codes and standards, strut-and-tie model (STM) is recommended as a rational approach for deep beam analyses. This research focuses on the STM recommended by ACI 318-11 and AASHTO LRFD and uses experimental results to modify the strut effectiveness factor in STM for reinforced concrete (RC) deep beams. This study aims to refine STM through the strut effectiveness factor and increase result accuracy. Six RC deep beams with different shear span to effective-depth ratios (a/d) of 0.75, 1.00, 1.25, 1.50, 1.75, and 2.00 were experimentally tested under a four-point bending set-up. The ultimate shear strength of deep beams obtained from non-linear finite element modeling and STM recommended by ACI 318-11 as well as AASHTO LRFD (2012) were compared with the experimental results. An empirical equation was proposed to modify the principal tensile strain value in the bottle-shaped strut of deep beams. The equation of the strut effectiveness factor from AASHTTO LRFD was then modified through the aforementioned empirical equation. An investigation on the failure mode and crack propagation in RC deep beams subjected to load was also conducted.

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http://www.plosone.org/article/fetchObject.action?uri=info:doi/10.1371/journal.pone.0130734&representation=PDF

A microstrip-line feed simple design of modified rectangular slotted patch antenna is proposed fo... more A microstrip-line feed simple design of modified rectangular slotted patch antenna is proposed for dual-frequency operation. The typical rectangular shape of the patch is reformed by integrating slots and extending the radiating patch to some extent for achieving desired resonance. With the optimized dimensions from numerical simulating software, the proposed antenna is printed on 1.905-mm-thick 40 x 40 mm(2) ceramic composite substrate with relative dielectric constant epsilon(r)=10.2. The experimental results confirm the bandwidths for S11 -10 dB are of 780 MHz (1.13-1.91 GHz) and 1.22 GHz (4.83-6.05 GHz) with resonance frequency 1.48 and 5.61 GHz, respectively. The antenna prototype shows almost consistent and symmetrical radiation patterns with maximum gain of 3.42 and 4.37 dBi for lower and upper frequency band, respectively. On the basis of well-agreed simulated and measured results, adequate bandwidth, stable radiation, and acceptable gain performance make the antenna suitable for serving simultaneously in global positioning system and wireless local area network bands. (c) 2015 Wiley Periodicals, Inc. Microwave Opt Technol Lett 57:2204-2207, 2015

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http://onlinelibrary.wiley.com/doi/10.1002/mop.29290/abstract

This study examined the interface pressure differences at the stump socket between an ICRC polypr... more This study examined the interface pressure differences at the stump socket between an ICRC polypropylene socket and an air splint socket for a common wearer of transhumeral amputee using F-socket transducers. Two F-socket sensors arrays were attached to the residual limb. The subject was asked to complete the following tasks: Normal position, stand in a normal position without conducting any motion and shoulder movements, flexion/extension and abduction. The results revealed that the interface pressure applied using ICRC polypropylene socket was maximize at the end distal of the residual limb and give more pressure contact to any shoulder movements. Conversely, while using air splint socket, the socket was able to auto-adjust for required socket fitting even for any change while doing shoulder movements. Our result demonstrated how the comparison of pressure applied at the stump socket may lead in chosen the suitable prosthetic's socket for the amputee. The impending development of an auto adjusted socket that uses an air splint system will provide the prosthetic socket with a less contact pressure at the residual limb. (c) 2014 Nalecz Institute of Biocybemetics and Biomedical Engineering. Published by Elsevier Sp. z o.o. All rights reserved.

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http://www.sciencedirect.com/science/article/pii/S0208521614000680
http://ac.els-cdn.com/S0208521614000680/1-s2.0-S0208521614000680-main.pdf?_tid=486f66d0-4012-11e5-9881-00000aab0f6c&acdnat=1439288477_84aa333e2d6d2d3f990852d5315e430a

The present work highlighted on the implementation of a unique concept for stabilizing colloids a... more The present work highlighted on the implementation of a unique concept for stabilizing colloids at their incipiently low charge potential. A highly charged nanoparticle was introduced within a coagulated prone colloidal system, serving as stabilizer to resist otherwise rapid flocculation and sedimentation process. A low size asymmetry of nanoparticle/colloid serves as the new topic of investigation in addition to the well-established large size ratio nanoparticle/microparticle study. Highly charged Al2O3 nanoparticles were used within the present research context to stabilize TiO2 and Fe3O4 based colloids via the formation of composite structures. It was believed, based on the experimental evidence, that Al2O3 nanoparticle interact with the weakly charged TiO2 and Fe3O4 colloids within the binary system via absorption and/or haloing modes to increase the overall charge potential of the respective colloids, thus preventing further surface contact via van der Waal's attraction. Series of experimental results strongly suggest the presence of weakly charged colloids in the studied bimodal system where, in the absence of highly charged nanoparticle, experience rapid instability. Absorbance measurement indicated that the colloidal stability drops in accordance to the highly charged nanoparticle sedimentation rate, suggesting the dominant influence of nanoparticles to attain a well-dispersed binary system. Further, it was found that the level of colloidal stability was enhanced with increasing nanoparticle fraction within the mixture. Rheological observation revealed that each hybrid complexes demonstrated behavior reminiscence to water with negligible increase in viscosity which serves as highly favorable condition particularly in thermal transport applications. (C) 2015 Elsevier Inc. All rights reserved.

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http://www.sciencedirect.com/science/article/pii/S0021979715004737
http://www.ncbi.nlm.nih.gov/pubmed/26048724
http://ac.els-cdn.com/S0021979715004737/1-s2.0-S0021979715004737-main.pdf?_tid=ce0ba0b4-400e-11e5-bd80-00000aab0f01&acdnat=1439286983_2e7e7d71352848240907e202d8ffeac3

The present research highlighted on the use of Reduced Graphene Oxide (RGO) and its hybrid comple... more The present research highlighted on the use of Reduced Graphene Oxide (RGO) and its hybrid complexes in an effort to improve the convective heat transfer performance in closed conduit configuration. The RGO was synthesized via the reduction process of chemically exfoliated Graphene Oxide (GO) using Tannic Acid (TA) as reductant. Different amount of pristine carbon sources (i.e. Multiwall Carbon Nanotube (MWCNT), Carbon Nanofiber (CNF) and Graphene nanoPlatelets (GnP)) was allowed to interact with RGO to form a hybrid complexes aiming to explore the capability of the mixtures to promote heat transfer process. It was discovered that the trend of results appeared to coincide to the previous documented findings on heat transfer enhancement related to the addition of graphene based materials. Further, the enhancement of heat transfer coefficient was beyond the increase in thermal conductivity alone which suggested prominent contribution from both the particle and turbulent induced flow characteristics. The enhancement was more pronounced at the entrance of the heating section as well as at high Reynolds number (Re), paving opportunities for further investigation to gain in-depth understanding on the mechanisms involved. As high as 144% enhancement in Nu was recorded near the conduit entrance and about 63% at the downstream section. Studies on hydrodynamic parameters indicated negligible increase in pressure loss as well as friction factor for RGO and its hybrid mixtures, indicating the potential use of RGO as favorable additives in addressing the persistent limitation of conventional heat transfer liquid within the perspective of convective heat transport system. (C) 2015 Elsevier Inc. All rights reserved.

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http://www.sciencedirect.com/science/article/pii/S0894177715000916
http://ac.els-cdn.com/S0894177715000916/1-s2.0-S0894177715000916-main.pdf?_tid=d31ed76a-400e-11e5-a2b2-00000aab0f6b&acdnat=1439286992_03d25205d39e571f4f7c5def0550f86e

The present research reported on the benign and facile preparation of highly stable reduced graph... more The present research reported on the benign and facile preparation of highly stable reduced graphene oxide (RGO) and its role on enhancing the thermophysical properties of heat transfer liquid. Graphene oxide (GO) was prepared via chemical exfoliation route and subsequently reduced using tannic acid (TA) which served as natural based environmentally benign reducing agent. Further, a meticulous amount of different high purity carbon sources (i.e. multiwall carbon nanotube (MWCNT), carbon nano-fiber (CNF) and graphene nanoplatelets (GnP)) was introduced to the RGO sheets aiming to extend the limits of its physicochemical properties for diverse applications. Results obtained led to the fact that GO was successfully reduced based on the material characterization evidences. Moreover, the addition of highly conjugated carbon structures on RGO has proven to be pivotal in promoting highly efficient thermal transport with minimal penalty on viscosity increment. It was believed that, similar to the previously documented electrical conductivity enhancement, the rise in thermal property was attributed to the modified structural network of RGO originating from the addition of different carbon allotropes which overlaid series of conducting paths for efficient phonon transport both in lateral and out of plane modes. As high as 25% increase in thermal conductivity was recorded with RGO-CNT complexes in comparison to base fluid (i.e. DI water) while a modest 4% rise in viscosity was proven to be insignificant. It was suggested from the results that morphological structure of the carbon based additives may play significant roles in different degree of enhancement of the hybrid materials. (C) 2015 Elsevier Ltd. All rights reserved.

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http://www.sciencedirect.com/science/article/pii/S0017931015003774
http://ac.els-cdn.com/S0017931015003774/1-s2.0-S0017931015003774-main.pdf?_tid=d5e98760-400e-11e5-90fa-00000aacb362&acdnat=1439286996_8ad62a5647a9d2cc20b471df68533309

Diamond-like carbon (DLC) coatings have emerged as one of the most promising surface coatings for... more Diamond-like carbon (DLC) coatings have emerged as one of the most promising surface coatings for applications involving boundary lubrication regime. Some of the characteristics that distinguish DLC coatings from other hard coatings include high hardness, low friction coefficient, wear resistance, and chemical inertness. Because of their low surface energies, these coatings cannot react effectively with different lubricant constituents. Doping of DLC coatings with metals and nonmetals, such as titanium, tungsten, silicon, chromium, fluorine, and nitrogen, can improve their interaction with lubricants to form tribologically beneficial films. Many experimental studies have been conducted on different types of DLC coatings using various lubricant formulations in the last few decades. The results obtained from these experimental studies are very scattered and contradictory, so the data should be consolidated in a more organized and apprehensible manner. By doing so, tribological behavior of various DLC-lubricant combinations can be understood in a better way, and a more logical continuation of research on DLC coatings can be carried out. In this review paper, most widely investigated metal-and nonmetal-doped DLC coatings, such as Ti-DLC, W-DLC, Si-DLC, Cr-DLC, WC-DLC, and multilayered a-C:H/W-DLC coatings, are considered for evaluation. Tribological performance of the aforementioned DLC coatings, in combination with various base oils and lubricant additives, is analyzed by comparing their average friction and wear coefficient values, which have been calculated from published experimental data. Only self-mated doped DLC contacts are considered in this study to eradicate the interference of ferrous and nonferrous counterbodies.

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http://link.springer.com/article/10.1007/s11249-015-0506-5
http://umexpert.um.edu.my/file/publication/00003184_119872.pdf
https://www.infona.pl/resource/bwmeta1.element.springer-9ca01c56-cef2-3424-86a7-0aab80faefaf

C-type natriuretic peptide (CNP) exhibits potent anti-inflammatory effects in chondrocytes that h... more C-type natriuretic peptide (CNP) exhibits potent anti-inflammatory effects in chondrocytes that have the potential to repair cartilage damage observed in osteoarthritis (OA). However, treatments for OA have been challenging due to poor targeting and delivery of therapeutics. The present study fabricated polyelectrolyte microcapsules loaded with CNP and examined whether the layer-by-layer (LbL) approach could have protective effects in cartilage explants treated with the pro-inflammatory cytokine, interleukin-1 beta (IL-1 beta). SEM showed uniform, 2 to 3 mu m spherical microcapsules with morphological characteristic similar to templates loaded with or without CNP. The protein was localized around the external surface of the microcapsules with encapsulation efficiencies >82.9%. CNP release profiles were broadly similar following 9 days of culture. The presence of CNP microcapsules did not significantly affect cell viability (80%) with DNA values that remained stable throughout the culture conditions. Confocal imaging showed clustering of microcapsules in chondrocytes to natriuretic peptide receptor (Npr) 2 and 3. Treatment of cartilage explants with CNP microcapsules led to concentration-dependent inhibition of NO release in response to IL-1 beta and restoration of matrix synthesis. In summary, we demonstrate controlled delivery of CNP to dampen pro-inflammatory effects induced by IL-1 beta in cartilage explants. The LbL approach has the potential to promote cartilage repair in vivo.

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http://pubs.acs.org/doi/abs/10.1021/bm501575w

Cryopreservation represents an effective technique to maintain the functional properties of human... more Cryopreservation represents an effective technique to maintain the functional properties of human adipose-derived stem cells (ASCs) and allows pooling of cells via long-term storage for clinical applications, e.g., cell-based therapies. It is crucial to reduce freezing injury during the cryopreservation process by loading the ASCs with the optimum concentration of suitable cryoprotective agents (CPAs). In this study, human ASCs were preserved for 3 months in different combinations of CPAs, including 1) 0.25 M trehalose; 2) 5% dimethylsulfoxide (DMSO); 3) 10% DMSO; 4) 5% DMSO + 20% fetal bovine serum (FBS); 5) 10% DMSO 1 20% FBS; 6) 10% DMSO + 90% FBS. Interestingly, even with a reduction of DMSO to 5% and without FBS, cryopreserved ASCs maintained high cell viability comparable with standard cryomedium (10% DMSO 1 90% FBS), with normal cell phenotype and proliferation rate. Cryopreserved ASCs also maintained their differentiation capability (e.g., to adipocytes, osteocytes and chondrocytes) and showed an enhanced expression level of stemness markers (e.g., NANOG, OCT-4, SOX-2 and REX-1). Our findings suggest that 5% DMSO without FBS may be an ideal CPA for an efficient long-term cryopreservation of human ASCs. These results aid in establishing standardized xeno-free long-term cryopreservation of human ASCs for clinical applications.

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http://www.nature.com/srep/2015/150413/srep09596/full/srep09596.html
http://europepmc.org/articles/pmc4397835
http://www.ncbi.nlm.nih.gov/pubmed/25872464

The objective of this research was to deposit a silicon carbide (SiC) reinforced layer of P25 (ir... more The objective of this research was to deposit a silicon carbide (SiC) reinforced layer of P25 (iron-based matrix material) on substrate material surface using CO2 laser. Two experiments using CO2 laser were carried out in this research. In the first experiment set, a gravity feed system was used with one powder feed containing different percentages of SiC particles and iron-based powder. In the second experiment set, preplaced powder was placed on substrate material surface. According to the experimental results, only few SiC particles were found in the clad matrix in the first experiment, and no SiC particles were found in the second experiment. A high microhardness value was noted in the SiC clad (above 1000 HV) in the first experiment compared to the second experiment with hardness values ranging from 200 HV to 700 HV. This was due to the high precipitation of carbide particles in the clad material during the first experiment. A comparison of the two different experiments signifies that the first one was the best because a more uniform layer with less porosity was produced.

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http://manufacturingscience.asmedigitalcollection.asme.org/article.aspx?articleid=2130671

This paper presents the effects of low volume fraction (V-f) of polyvinyl alcohol (PVA) fibers on... more This paper presents the effects of low volume fraction (V-f) of polyvinyl alcohol (PVA) fibers on the mechanical properties of oil palm shell (OPS) high strength lightweight concrete mixtures. The slump, density, compressive strength, splitting tensile strength, flexural strength, and modulus of elasticity under various curing conditions have been measured and evaluated. The results indicate that an increase in PVA fibers decreases the workability of the concrete and decreases the density slightly. The 28-day compressive strength of oil palm shell fiber-reinforced concrete (OPSFRC) high strength lightweight concrete (HSLWC) subject to continuous moist curing was within the range of 43-49 MPa. The average modulus of elasticity (E) value is found to be 16.1 GPa for all mixes, which is higher than that reported in previous studies and is within the range of normal weight concrete. Hence, the findings of this study revealed that the PVA fibers can be used as an alternative material to enhance the properties of OPS HSLWC for building and construction applications.

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http://downloads.hindawi.com/journals/amse/2015/425236.pdf

This study aims to investigate the use of various polypropylene (PP) fibres with different aspect... more This study aims to investigate the use of various polypropylene (PP) fibres with different aspect ratio and geometry to enhance the mechanical properties of oil palm shell fibre-reinforced lightweight concrete. The volume fractions (V-f) of 0.25%, 0.375% and 0.5% were studied for each fibre. As various PP fibres were added into oil palm shell fibre reinforced concrete, the marginal density reduction was reported. The effectiveness of new types of PP fibres to increase the compressive strength at later ages was more pronounced than at early age. It is found that low volume fractions of polypropylene twisted bundle (PPTB) fibres are more effective in improving the flexural strength of OPS concrete compared to its splitting tensile strength. The average modulus of elasticity (E value) is obtained to be 13.4 GPa for all mixes, which is higher than the values reported in previous studies. An increase in the percentage third load compressive strength of 0.5% PPTB fibre of up to 11% was reported. Hence, this new types of PP fibres is a promising alternative solution to compensate lower mechanical properties for lightweight concrete. (C) 2015 Elsevier Ltd. All rights reserved.

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http://ac.els-cdn.com/S0950061815004675/1-s2.0-S0950061815004675-main.pdf?_tid=e46ea1b2-400e-11e5-bd2f-00000aab0f6b&acdnat=1439287021_23a4a22a788c532a02cc6e0cec44941e

Anodizing could be used for bio-functionalization of the surfaces of titanium alloys. In this stu... more Anodizing could be used for bio-functionalization of the surfaces of titanium alloys. In this study, we use anodizing for creating nanotubes on the surface of porous titanium alloy bone substitutes manufactured using selective laser melting. Different sets of anodizing parameters (voltage: 10 or 20 V anodizing time: 30 min to 3 h) are used for anodizing porous titanium structures that were later heat treated at 500 degrees C. The nanotopographical features are examined using electron microscopy while the bioactivity of anodized surfaces is measured using immersion tests in the simulated body fluid (SBF). Moreover, the effects of anodizing and heat treatment on the performance of one representative anodized porous titanium structures are evaluated using in vitro cell culture assays using human periosteum-derived cells (hPDCs). It has been shown that while anodizing with different anodizing parameters results in very different nanotopographical features, i.e. nanotubes in the range of 20 to 55 nm, anodized surfaces have limited apatite-forming ability regardless of the applied anodizing parameters. The results of in vitro cell culture show that both anodizing, and thus generation of regular nanotopographical feature, and heat treatment improve the cell culture response of porous titanium. In particular, cell proliferation measured using metabolic activity and DNA content was improved for anodized and heat treated as well as for anodized but not heat-treated specimens. Heat treatment additionally improved the cell attachment of porous titanium surfaces and upregulated expression of osteogenic markers. Anodized but not heat-treated specimens showed some limited signs of upregulated expression of osteogenic markers. In conclusion, while varying the anodizing paraineters creates different nanotube structure, it does not improve apatite-forming ability of porous titanium. However, both anodizing and heat treatment at 500 degrees C improve the cell culture response of porous titanium. (C) 2015 Elsevier B.V. All rights reserved.

Link to Full-Text Articles :
http://www.sciencedirect.com/science/article/pii/S0928493115001708
http://europepmc.org/abstract/med/25842117
https://lirias.kuleuven.be/handle/123456789/489802
http://ac.els-cdn.com/S0928493115001708/1-s2.0-S0928493115001708-main.pdf?_tid=ebad7426-400e-11e5-8d20-00000aab0f01&acdnat=1439287033_6cf014c34b7f8e3558724d8ee5499630

A practical case study on the air distribution in an operating room (OR) at University of Malaya ... more A practical case study on the air distribution in an operating room (OR) at University of Malaya Medical Centre, Kuala Lumpur is presented. The OR has a relatively large floor area since it is connected with the medical storage room and served by a total of 14 room air inlets and 3 exhausts. The room air inlets are located at the peripheral of the surgical site rather than just above the surgical site. From the measurement conducted, the average room inlet air velocity was 0.19m/s with a standard deviation of 0.03m/s for all inlets and 33.5 air change per hour. In line with its current design, the air distribution was simulated using the computational fluid dynamics software. Initial simulation with the room air inlet velocity of 0.2m/s showed an improper airflow at the surgical site. However, this condition was not significantly improved even by doubling the inlet velocity. The results have identified that with air inlets located at the peripheral of surgical site, the air inlet design was unable to provide a satisfactory airflow across the surgical site, and hence not appropriate for the purpose of its intended use.

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http://ibe.sagepub.com/content/24/3/355.full.pdf

In the present experimental work, a new synthesis method is introduced for decoration of silver o... more In the present experimental work, a new synthesis method is introduced for decoration of silver on the functionalized graphene nanoplatelets (GNP-Ag) and preparation of nanofluids is reported. The thermo-physical properties, heat transfer performance and friction factor for fully developed turbulent flow of GNP-Ag/water nanofluids flowing through a circular tube at a constant heat flux were investigated. GNP-Ag uniform nanocomposite was produced from a simple chemical reaction procedure, which includes acid treatment for functionalization of GNP. The surface characterization was performed by various techniques such as XRD, FESEM, TEM and Raman. The GNP-Ag nanofluids were prepared by dispersing the nanocomposite in distilled water without the assistance of a surfactant and/or ultrasonication. The prepared nanofluids were found to be stable and no sedimentation was observed for a long time. The experimental data for GNP-Ag nanofluids were shown improvements of effective thermal conductivity and heat transfer efficiency in comparison with the corresponding to the base-fluid. The amount of enhancement was a function of temperature and weight concentration of nanoparticles. Maximum enhancement of Nusselt number was 32.7% with a penalty of 1.08 times increase in the friction factor for the weight concentration of 0.1% at a Reynolds number of 17,500 compared to distilled water. Improved empirical correlations were proposed based on the experimental data for evaluation of Nusselt number and friction factor. (C) 2015 Elsevier Ltd. All rights reserved.

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http://www.sciencedirect.com/science/article/pii/S0196890415004707
http://ac.els-cdn.com/S0196890415004707/1-s2.0-S0196890415004707-main.pdf?_tid=f437362c-400e-11e5-b3a0-00000aacb360&acdnat=1439287047_c777af79a83ae6d83a9d8f3aa275a161

Zn-Al-Mg cast alloys with different Mg contents were prepared and characterized in this research.... more Zn-Al-Mg cast alloys with different Mg contents were prepared and characterized in this research. The solidification process of melt liquids and the formation mechanism of intermetallic were analyzed. The influence of microstructure on corrosion resistance property of alloy was also investigated. Results show that the microhardness of Zn-Al-Mg alloys increase with the increasing of Mg content, which is due to the grain refining effect. Ternary eutectic structures (Zn/Al/Zn-Mg intermetallic) were found in Zn-Al-Mg alloys. Polarization analyse reveals that Zn-5 wt.% Al-2 wt.% Mg (ZA5M2) alloy has the lowest corrosion current density of 1.03 x 10(-3) A/cm(2) among all tested samples. Electrochemical impedance spectroscopy indicates that with the increasing of Mg content, the resistance of corrosion product increases from about 930 Omega of Zn-5 wt.% Al alloy to 8360 Omega of ZA5M2 alloy. The formation of nanostructured eutectic Zn/Al/Mg2Zn11 is probably the key factor of the improved corrosion property. (C) 2015 Elsevier B.V. All rights reserved.

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http://www.sciencedirect.com/science/article/pii/S0925838815012906
http://ac.els-cdn.com/S0925838815012906/1-s2.0-S0925838815012906-main.pdf?_tid=fbc5e35c-400e-11e5-b09d-00000aab0f01&acdnat=1439287060_d850c9af6c70e87dea5f19b0280da7a8