Displaying publications 61 - 80 of 737 in total

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  1. Synthesis of metallic mixed 3R and 2H Nb1+xS2 nanoflakes by chemical vapor deposition
    Mohmad AR, Hamzah AA, Yang J, Wang Y, Bozkurt I, Shin HS, et al.
    Faraday Discuss, 2021 Apr 01;227:332-340.
    PMID: 33523053 DOI: 10.1039/c9fd00132h
    In this work, we report the synthesis and characterization of mixed phase Nb1+xS2 nanoflakes prepared by chemical vapor deposition. The as-grown samples show a high density of flakes (thickness ∼50 nm) that form a continuous film. Raman and X-ray diffraction data show that the samples consist of both 2H and 3R phases, with the 2H phase containing a high concentration of Nb interstitials. These Nb interstitials sit in between the NbS2 layers to form Nb1+xS2. Cross-sectional Energy Dispersive Spectroscopy analysis with transmission electron microscopy suggests that the 2H Nb1+xS2 region is found in thinner flakes, while 3R NbS2 is observed in thicker regions of the films. The evolution of the phase from 2H Nb1+xS2 to 3R NbS2 may be attributed to the change of the growth environment from Nb-rich at the start of the growth to sulfur-rich at the latter stage. It was also found that the incorporation of Nb interstitials is highly dependent on the temperature of the NbCl5 precursor and the position of the substrate in the furnace. Samples grown at high NbCl5 temperature and with substrate located closer to the NbCl5 source show higher incorporation of Nb interstitials. Electrical measurements show linear I-V characteristics, indicating the metallic nature of the Nb1+xS2 film with relatively low resistivity of 4.1 × 10-3Ω cm.
    Matched MeSH terms: Hot Temperature
  2. Fulltext Species-specific identification of porcine blood plasma in heat-treated chicken meatballs
    Shahimi S, Abd Mutalib S, Ismail N, Elias A, Hashim H, Kashim MIAM
    Saudi J Biol Sci, 2021 Apr;28(4):2447-2452.
    PMID: 33911957 DOI: 10.1016/j.sjbs.2021.01.043
    This study was conducted to detect the presence of chicken and porcine DNA in meatballs using mitochondria DNA (mtDNA) of cytochrome b (cyt b) and nuclear DNA (nDNA) short interspersed nuclear element (SINE) species-specific primers, respectively. While, the mtDNA primers targeted transfer RNA-ATP8 (tRNA-ATP8) gene was used for 1 and 5% (w/w) chicken meatball spiked with commercial porcine blood plasm. Chicken meatballs spiked with 1% and 5% (v/w) fresh and commercial porcine blood plasma, respectively were prepared and heat-treated using five (n = 5) cooking methods: boiling, pan-frying, roasting, microwaving and autoclaving. Two pairs of mtDNA and nDNA primers used, produced 129 and 161 bp amplicons, respectively. Whereas, tRNA-ATP8 primers produced 212 bp of amplicon. Electrophoresis analysis showed positive results for porcine DNA at 1% and 5% (w/w or v/v) for all of the different cooking techniques, either for fresh or commercial blood plasma using SINE primers but not for tRNA-ATP8 primers. The present study has highlighted the useful of species-specific primers of SINE primers in PCR analysis for detecting porcine DNA blood plasma in heat-treated chicken meatballs.
    Matched MeSH terms: Hot Temperature
  3. Fulltext Comparison between airborne ultrasound and contact ultrasound to intensify air drying of blackberry: Heat and mass transfer simulation, energy consumption and quality evaluation
    Tao Y, Li D, Siong Chai W, Show PL, Yang X, Manickam S, et al.
    Ultrason Sonochem, 2021 Apr;72:105410.
    PMID: 33341708 DOI: 10.1016/j.ultsonch.2020.105410
    This study aimed at investigating the performances of air drying of blackberries assisted by airborne ultrasound and contact ultrasound. The drying experiments were conducted in a self-designed dryer coupled with a 20-kHz ultrasound probe. A numerical model for unsteady heat and mass transfer considering temperature dependent diffusivity, shrinkage pattern and input ultrasonic energies were applied to explore the drying mechanism, while the energy consumption and quality were analyzed experimentally. Generally, both airborne ultrasound and contact ultrasound accelerated the drying process, reduced the energy consumption and enhanced the retentions of blackberry anthocyanins and organic acids in comparison to air drying alone. At the same input ultrasound intensity level, blackberries received more ultrasound energies under contact sonication (0.299 W) than airborne sonication (0.245 W), thus avoiding the attenuation of ultrasonic energies by air. The modeling results revealed that contact ultrasound was more capable than airborne ultrasound to intensify the inner moisture diffusion and heat conduction, as well as surface exchange of heat and moisture with air. During air drying, contact ultrasound treatment eliminated the gradients of temperature and moisture inside blackberry easier than airborne ultrasound, leading to more homogenous distributions. Moreover, the total energy consumption under air drying with contact ultrasound assistance was 27.0% lower than that with airborne ultrasound assistance. Besides, blackberries dehydrated by contact ultrasound contained more anthocyanins and organic acids than those dried by airborne ultrasound, implying a higher quality. Overall, direct contact sonication can well benefit blackberry drying in both energy and quality aspects.
    Matched MeSH terms: Hot Temperature*
  4. Fulltext A Short Review on the Phase Structures, Oxidation Kinetics, and Mechanical Properties of Complex Ti-Al Alloys
    Lim HP, Liew WYH, Melvin GJH, Jiang ZT
    Materials (Basel), 2021 Mar 29;14(7).
    PMID: 33805462 DOI: 10.3390/ma14071677
    This paper reviews the phase structures and oxidation kinetics of complex Ti-Al alloys at oxidation temperatures in the range of 600-1000 °C. The mass gain and parabolic rate constants of the alloys under isothermal exposure at 100 h (or equivalent to cyclic exposure for 300 cycles) is compared. Of the alloying elements investigated, Si appeared to be the most effective in improving the oxidation resistance of Ti-Al alloys at high temperatures. The effect of alloying elements on the mechanical properties of Ti-Al alloys is also discussed. Significant improvement of the mechanical properties of Ti-Al alloys by element additions has been observed through the formation of new phases, grain refinement, and solid solution strengthening.
    Matched MeSH terms: Hot Temperature
  5. Enhancing erythrocyte-influenza virus specificity by glycan-conjugated gold nanoparticle: Validation of hemagglutination by aptamer and neuraminidases
    Ye M, Lin L, Yang W, Gopinath SCB
    Biotechnol Appl Biochem, 2021 Mar 26.
    PMID: 33769582 DOI: 10.1002/bab.2152
    This study demonstrated the terminated sialo-sugar chains (Neu5Acα2,6Gal and Neu5Acα2,3Gal) mediated specificity enhancement of influenza virus and chicken red blood cell (RBC) by hemagglutination assay. These glycan chains were immobilized on the gold nanoparticle (GNP) to withhold the higher numbers. With the preliminary optimization, a clear button formation with 0.5% RBC was visualized. On the other hand, intact B/Tokio/53/99 with 750 nM hemagglutinin (HA) displayed a nice hemagglutination. The interference on the specificity of RBC and influenza virus was observed by anti-influenza aptamer at the concentration 31 nM, however, there is no hemagglutination prevention was noticed in the presence of complementary aptamer sequences. Spiking GNP conjugated Neu5Acα2,6Gal or Neu5Acα2,3Gal or a mixture of these two to the reaction promoted the hemagglutination to 63 folds higher with 12 nM virus, whereas under the same condition the heat inactivated viruses were lost the hemagglutination. Neuraminidases from Clostridium perfringens and Arthrobacter ureafaciens at 0.0025 neuraminidase units are able to abolish the hemagglutination. Other enzymes, Glycopeptidase F (Elizabethkingia meningoseptica) and Endoglycosidase H (Streptomyces plicatus) did not show the changes with agglutination. Obviously, sialyl-Gal-terminated glycan conjugated GNP amendment has enhanced the specificity of erythrocyte-influenza virus and able to be controlled by aptamer or neuraminidases. This article is protected by copyright. All rights reserved.
    Matched MeSH terms: Hot Temperature
  6. Fulltext Self-Fluxing Mechanism in Geopolymerization for Low-Sintering Temperature of Ceramic
    Jamil NH, Abdullah MMAB, Pa FC, Mohamad H, Ibrahim WMAW, Amonpattaratkit P, et al.
    Materials (Basel), 2021 Mar 10;14(6).
    PMID: 33801862 DOI: 10.3390/ma14061325
    Kaolin, theoretically known as having low reactivity during geopolymerization, was used as a source of aluminosilicate materials in this study. Due to this concern, it is challenging to directly produce kaolin geopolymers without pre-treatment. The addition of ground granulated blast furnace slag (GGBS) accelerated the geopolymerization process. Kaolin-GGBS geopolymer ceramic was prepared at a low sintering temperature due to the reaction of the chemical composition during the initial stage of geopolymerization. The objective of this work was to study the influence of the chemical composition towards sintering temperature of sintered kaolin-GGBS geopolymer. Kaolin-GGBS geopolymer was prepared with a ratio of solid to liquid 2:1 and cured at 60 °C for 14 days. The cured geopolymer was sintered at different temperatures: 800, 900, 1000, and 1100 °C. Sintering at 900 °C resulted in the highest compressive strength due to the formation of densified microstructure, while higher sintering temperature led to the formation of interconnected pores. The difference in the X-ray absorption near edge structure (XANES) spectra was related to the phases obtained from the X-ray diffraction analysis, such as akermanite and anothite. Thermal analysis indicated the stability of sintered kaolin-GGBS geopolymer when exposed to 1100 °C, proving that kaolin can be directly used without heat treatment in geopolymers. The geopolymerization process facilitates the stability of cured samples when directly sintered, as well as plays a significant role as a self-fluxing agent to reduce the sintering temperature when producing sintered kaolin-GGBS geopolymers.
    Matched MeSH terms: Hot Temperature
  7. Structural and functional characterisation of a cold-active yet heat-tolerant dehydroquinase from Glaciozyma antarctica PI12
    Jaafar NR, Mahadi NM, Mackeen MM, Illias RM, Murad AMA, Abu Bakar FD
    J Biotechnol, 2021 Mar 10;329:118-127.
    PMID: 33539893 DOI: 10.1016/j.jbiotec.2021.01.019
    Dehydroquinase or 3-dehydroquinate dehydratase (DHQD) reversibly cleaves 3-dehydroquinate to form 3-dehydroshikimate. Here, we describe the functional and structural features of a cold active type II 3-dehydroquinate dehydratase from the psychrophilic yeast, Glaciozyma antarctica PI12 (GaDHQD). Functional studies showed that the enzyme was active at low temperatures (10-30 °C), but displayed maximal activity at 40 °C. Yet the enzyme was stable over a wide range of temperatures (10-70 °C) and between pH 6.0-10.0 with an optimum pH of 8.0. Interestingly, the enzyme was highly thermo-tolerant, denaturing only at approximately 84 °C. Three-dimensional structure analyses showed that the G. antarctica dehydroquinase (GaDHQD) possesses psychrophilic features in comparison with its mesophilic and thermophilic counterparts such as higher numbers of non-polar residues on the surface, lower numbers of arginine and higher numbers of glycine-residues with lower numbers of hydrophobic interactions. On the other hand, GaDHQD shares some traits (i.e. total number of hydrogen bonds, number of proline residues and overall folding) with its mesophilic and thermophilic counterparts. Combined, these features contribute synergistically towards the enzyme's ability to function at both low and high temperatures.
    Matched MeSH terms: Hot Temperature*
  8. Fulltext Laser-Assisted High Speed Machining of 316 Stainless Steel: The Effect of Water-Soluble Sago Starch Based Cutting Fluid on Surface Roughness and Tool Wear
    Yasmin F, Tamrin KF, Sheikh NA, Barroy P, Yassin A, Khan AA, et al.
    Materials (Basel), 2021 Mar 09;14(5).
    PMID: 33803364 DOI: 10.3390/ma14051311
    Laser-assisted high speed milling is a subtractive machining method that employs a laser to thermally soften a difficult-to-cut material's surface in order to enhance machinability at a high material removal rate with improved surface finish and tool life. However, this machining with high speed leads to high friction between workpiece and tool, and can result in high temperatures, impairing the surface quality. Use of conventional cutting fluid may not effectively control the heat generation. Besides, vegetable-based cutting fluids are invariably a major source of food insecurity of edible oils which is traditionally used as a staple food in many countries. Thus, the primary objective of this study is to experimentally investigate the effects of water-soluble sago starch-based cutting fluid on surface roughness and tool's flank wear using response surface methodology (RSM) while machining of 316 stainless steel. In order to observe the comparison, the experiments with same machining parameters are conducted with conventional cutting fluid. The prepared water-soluble sago starch based cutting fluid showed excellent cooling and lubricating performance. Therefore, in comparison to the machining using conventional cutting fluid, a decrease of 48.23% in surface roughness and 38.41% in flank wear were noted using presented approach. Furthermore, using the extreme learning machine (ELM), the obtained data is modeled to predict surface roughness and flank wear and showed good agreement between observations and predictions.
    Matched MeSH terms: Hot Temperature
  9. Fulltext Thermal Charging Optimization of a Wavy-Shaped Nano-Enhanced Thermal Storage Unit
    Ghalambaz M, Mehryan SAM, Hajjar A, Shdaifat MYA, Younis O, Talebizadehsardari P, et al.
    Molecules, 2021 Mar 09;26(5).
    PMID: 33803488 DOI: 10.3390/molecules26051496
    A wavy shape was used to enhance the thermal heat transfer in a shell-tube latent heat thermal energy storage (LHTES) unit. The thermal storage unit was filled with CuO-coconut oil nano-enhanced phase change material (NePCM). The enthalpy-porosity approach was employed to model the phase change heat transfer in the presence of natural convection effects in the molten NePCM. The finite element method was applied to integrate the governing equations for fluid motion and phase change heat transfer. The impact of wave amplitude and wave number of the heated tube, as well as the volume concertation of nanoparticles on the full-charging time of the LHTES unit, was addressed. The Taguchi optimization method was used to find an optimum design of the LHTES unit. The results showed that an increase in the volume fraction of nanoparticles reduces the charging time. Moreover, the waviness of the tube resists the natural convection flow circulation in the phase change domain and could increase the charging time.
    Matched MeSH terms: Hot Temperature
  10. Fulltext Head Cooling Prior to Exercise in the Heat Does Not Improve Cognitive Performance
    Mazalan NS, Landers GJ, Wallman KE, Ecker U
    J Sports Sci Med, 2021 03;20(1):69-76.
    PMID: 33707989 DOI: 10.52082/jssm.2021.69
    This study investigated the effectiveness of head cooling on cognitive performance after 30 min and 60 min of running in the heat. Ten moderately-trained, non-heat-acclimated, male endurance athletes (mean age: 22 ± 6.6 y; height: 1.78 ± 0.10 m; body-mass: 75.7 ± 15.6 kg; VO2peak: 51.6 ± 4.31 mL-1>kg-1>min) volunteered for this study. Participants performed two experimental trials: head cooling versus no-cooling (within-subjects factor with trial order randomized). For each trial, participants wore a head-cooling cap for 15 min with the cap either cooled to 0°C (HC) or not cooled (22°C; CON). Participants then completed 2 × 30 min running efforts on a treadmill at 70% VO2peak in hot conditions (35°C, 70% relative humidity), with a 10 min rest between efforts. Working memory was assessed using an operation span (OSPAN) task immediately prior to the 15 min cooling/no-cooling period (22°C, 35% RH) and again after 30 min and 60 min of running in the heat. Numerous physiological variables, including gastrointestinal core temperature (Tc) were assessed over the protocol. Scores for OSPAN were similar between trials, with no interaction effect or main effects for time and trial found (p = 0.58, p = 0.67, p = 0.54, respectively). Forehead temperature following precooling was lower in HC (32.4 ± 1.6°C) compared with CON (34.5 ± 1.1°C) (p = 0.01), however, no differences were seen in Tc, skin temperature, heart rate and ratings of perceived exertion between HC and CON trials at any time point assessed (p > 0.05). In conclusion, despite HC reducing forehead temperature prior to exercise, it did not significantly improve cognitive performance during (half-time break) or after subsequent exercise in hot environmental conditions, compared to a no cooling control.
    Matched MeSH terms: Hot Temperature
  11. Potential of using basa catfish oil as a promising alternative deep-frying medium: A thermo-oxidative stability study
    Khor YP, Wan SY, Tan CP, Zhao G, Li C, Wang Y, et al.
    Food Res Int, 2021 03;141:109897.
    PMID: 33641946 DOI: 10.1016/j.foodres.2020.109897
    Basa catfish is a good source for fish oil extraction, which was believed to have good thermo-oxidative stability because of its similar fatty acid composition to that of palm olein (PO). The thermo-oxidative stability of PO, basa catfish oil (FO), and palm olein-basa fish oil blend (PO-FO; ratio 1:1) was evaluated after 75 frying cycles. No significant difference was observed in p-anisidine value, TOTOX value, conjugated trienes, monomeric oxidized triacylglycerols, and free fatty acids concentration after frying. Moreover, compared to PO, FO exhibited lighter color, lower acid value, conjugated dienes, polymerized triacylglycerol, and total polar content. The PO-FO blend also demonstrated a more favorable frying stability compared to the other two frying systems. These findings indicated that FO could be proposed as a promising alternative to common PO, and its blending with other vegetable oils at an appropriate ratio might improve the overall oil frying quality for future industrial applications.
    Matched MeSH terms: Hot Temperature
  12. Fulltext Sustainable Production of Arecanut Husk Ash as Potential Silica Replacement for Synthesis of Silicate-Based Glass-Ceramics Materials
    Anuar MF, Fen YW, Azizan MZ, Rahmat F, Mohd Zaid MH, Khaidir REM, et al.
    Materials (Basel), 2021 Feb 28;14(5).
    PMID: 33670923 DOI: 10.3390/ma14051141
    Arecanut husk (AH) was selected as a material for silica replacement in the synthesis process of glass-ceramics zinc silicate and also the fact that it has no traditional use and often being dumped and results in environmental issues. The process of pyrolysis was carried out at temperature 700 °C and above based on thermogravimetric analysis to produce arecanut husk ash (AHA). The average purity of the silica content in AHA ranged from 29.17% to 45.43%. Furthermore, zinc oxide was introduced to AHA and zinc silicate started to form at sintering temperature 700 °C and showed increased diffraction intensity upon higher sintering temperature of 600 °C to 1000 °C based on X-ray diffraction (XRD) analysis. The grain sizes of the zinc silicate increased from 1011 nm to 3518 nm based on the morphological studies carried out by field emission scanning electron microscopy (FESEM). In addition, the optical band gap of the sample was measured to be in the range from 2.410 eV to 2.697 eV after sintering temperature. From the data, it is believed that a cleaner production of low-cost zinc silicate can be achieved by using arecanut husk and have the potential to be used as phosphors materials.
    Matched MeSH terms: Hot Temperature
  13. Fulltext The Effect of Welding Current and Electrode Force on the Heat Input, Weld Diameter, and Physical and Mechanical Properties of SS316L/Ti6Al4V Dissimilar Resistance Spot Welding with Aluminum Interlayer
    Taufiqurrahman I, Ahmad A, Mustapha M, Lenggo Ginta T, Ady Farizan Haryoko L, Ahmed Shozib I
    Materials (Basel), 2021 Feb 27;14(5).
    PMID: 33673716 DOI: 10.3390/ma14051129
    Welding parameters obviously determine the joint quality during the resistance spot welding process. This study aimed to investigate the effect of welding current and electrode force on the heat input and the physical and mechanical properties of a SS316L and Ti6Al4V joint with an aluminum interlayer. The weld current values used in this study were 11, 12, and 13 kA, while the electrode force values were 3, 4, and 5 kN. Welding time and holding time remained constant at 30 cycles. The study revealed that, as the welding current and electrode force increased, the generated heat input increased significantly. The highest tensile-shear load was recorded at 8.71 kN using 11 kA of weld current and 3 kN of electrode force. The physical properties examined the formation of a brittle fracture and several weld defects on the high current welded joint. The increase in weld current also increased the weld diameter. The microstructure analysis revealed no phase transformation on the SS316L interface; instead, the significant grain growth occurred. The phase transformation has occurred on the Ti6Al4V interface. The intermetallic compound layer was also investigated in detail using the EDX (Energy Dispersive X-Ray) and XRD (X-Ray Diffraction) analyses. It was also found that both stainless steel and titanium alloy have their own fusion zone, which is indicated by the highest microhardness value.
    Matched MeSH terms: Hot Temperature
  14. Fulltext Experimental Analysis of Heat-Affected Zone (HAZ) in Laser Cutting of Sugar Palm Fiber Reinforced Unsaturated Polyester Composites
    Masoud F, Sapuan SM, Ariffin MKAM, Nukman Y, Bayraktar E
    Polymers (Basel), 2021 Feb 26;13(5).
    PMID: 33652612 DOI: 10.3390/polym13050706
    In this paper, the influence of processing input parameters on the heat-affected zone (HAZ) of three different material thicknesses of sugar palm fiber reinforced unsaturated polyester (SPF-UPE) composites cut with a CO2 laser was investigated. Laser power, traverse speed, and gas pressure were selected as the most influential input parameters on the HAZ to optimize the HAZ response with fixing all of the other input parameters. Taguchi's method was used to determine the levels of parameters that give the best response to the HAZ. The significance of input parameters was also determined by calculating the max-min variance of the average of the signal-to-noise ratio (S/N) ratio for each parameter. Analysis of variation (ANOVA) was used to determine each input parameter's contribution to the influence on HAZ depth. The general results show that the minimum levels of laser power and the highest levels of traverse speed and gas pressure gave the optimum response to the HAZ. Gas pressure had the most significant effect on the HAZ, with contribution decreases as the material thickness increased, followed by the traverse speed with contribution increases with the increase in material thickness. Laser power came third, with a minimal contribution to the effect on the HAZ, and it did not show a clear relationship with the change in material thickness. By applying the optimum parameters, the desired HAZ depth could be obtained at relatively low values.
    Matched MeSH terms: Hot Temperature
  15. Fulltext Chimeric Virus-Like Particles of Prawn Nodavirus Displaying Hepatitis B Virus Immunodominant Region: Biophysical Properties and Cytokine Response
    Ninyio NN, Ho KL, Yong CY, Chee HY, Hamid M, Ong HK, et al.
    Int J Mol Sci, 2021 Feb 15;22(4).
    PMID: 33672018 DOI: 10.3390/ijms22041922
    Hepatitis B is a major global health challenge. In the absence of an effective treatment for the disease, hepatitis B vaccines provide protection against the viral infection. However, some individuals do not have positive immune responses after being vaccinated with the hepatitis B vaccines available in the market. Thus, it is important to develop a more protective vaccine. Previously, we showed that hepatitis B virus (HBV) 'a' determinant (aD) displayed on the prawn nodavirus capsid (Nc) and expressed in Spodoptera frugiperda (Sf9) cells (namely, Nc-aD-Sf9) self-assembled into virus-like particles (VLPs). Immunisation of BALB/c mice with the Nc-aD-Sf9 VLPs showed significant induction of humoral, cellular and memory B-cell immunity. In the present study, the biophysical properties of the Nc-aD-Sf9 VLPs were studied using dynamic light scattering (DLS) and circular dichroism (CD) spectroscopy. Enzyme-linked immunosorbent assay (ELISA) was used to determine the antigenicity of the Nc-aD-Sf9 VLPs, and multiplex ELISA was employed to quantify the cytokine response induced by the VLPs administered intramuscularly into BALB/c mice (n = 8). CD spectroscopy of Nc-aD-Sf9 VLPs showed that the secondary structure of the VLPs predominantly consisted of beta (β)-sheets (44.8%), and they were thermally stable up to ~52 °C. ELISA revealed that the aD epitope of the VLPs was significantly antigenic to anti-HBV surface antigen (HBsAg) antibodies. In addition, multiplex ELISA of serum samples from the vaccinated mice showed a significant induction (p < 0.001) of IFN-γ, IL-4, IL-5, IL-6, IL-10, and IL-12p70. This cytokine profile is indicative of natural killer cell, macrophage, dendritic cell and cytotoxic T-lymphocyte activities, which suggests a prophylactic innate and adaptive cellular immune response mediated by Nc-aD-Sf9 VLPs. Interestingly, Nc-aD-Sf9 induced a more robust release of the aforementioned cytokines than that of Nc-aD VLPs produced in Escherichia coli and a commercially used hepatitis B vaccine. Overall, Nc-aD-Sf9 VLPs are thermally stable and significantly antigenic, demonstrating their potential as an HBV vaccine candidate.
    Matched MeSH terms: Hot Temperature
  16. Fulltext Recent Progress on Stability and Thermo-Physical Properties of Mono and Hybrid towards Green Nanofluids
    Zainon SNM, Azmi WH
    Micromachines (Basel), 2021 Feb 11;12(2).
    PMID: 33670250 DOI: 10.3390/mi12020176
    Many studies have shown the remarkable enhancement of thermo-physical properties with the addition of a small quantity of nanoparticles into conventional fluids. However, the long-term stability of the nanofluids, which plays a significant role in enhancing these properties, is hard to achieve, thus limiting the performance of the heat transfer fluids in practical applications. The present paper attempts to highlight various approaches used by researchers in improving and evaluating the stability of thermal fluids and thoroughly explores various factors that contribute to the enhancement of the thermo-physical properties of mono, hybrid, and green nanofluids. There are various methods to maintain the stability of nanofluids, but this paper particularly focuses on the sonication process, pH modification, and the use of surfactant. In addition, the common techniques to evaluate the stability of nanofluids are undertaken by using visual observation, TEM, FESEM, XRD, zeta potential analysis, and UV-Vis spectroscopy. Prior investigations revealed that the type of nanoparticle, particle volume concentration, size and shape of particles, temperature, and base fluids highly influence the thermo-physical properties of nanofluids. In conclusion, this paper summarized the findings and strategies to enhance the stability and factors affecting the thermal conductivity and dynamic viscosity of mono and hybrid of nanofluids towards green nanofluids.
    Matched MeSH terms: Hot Temperature
  17. Fulltext Double Pulse Resistance Spot Welding of Dual Phase Steel: Parametric Study on Microstructure, Failure Mode and Low Dynamic Tensile Shear Properties
    Soomro IA, Pedapati SR, Awang M
    Materials (Basel), 2021 Feb 08;14(4).
    PMID: 33567606 DOI: 10.3390/ma14040802
    Resistance spot welding (RSW) of dual phase (DP) steels is a challenging task due to formation of brittle martensitic structure in the fusion zone (FZ), resulting in a low energy capacity of the joint during high-rate loading. In the present study, in situ postweld heat treatment (PWHT) was carried out by employing a double pulse welding scheme with the aim of improving the mechanical performance of DP590 steel resistance spot weld joint. Taguchi method was used to optimize in situ PWHT parameters to obtain maximum peak load and failure energy. Experiments were designed based on orthogonal array (OA) L16. Mechanical performance was evaluated in terms of peak load and failure energy after performing low dynamic tensile shear (TS) test. Microstructural characterization was carried out using a scanning electron microscope (SEM). The results show that improvements of 17 and 86% in peak load and failure energy, respectively, were achieved in double-pulse welding (DPW) at optimum conditions compared to traditional single-pulse welding (SPW). The improvement in mechanical performance resulted from (i) enlargement of the FZ and (ii) improved weld toughness due to tempering of martensite in the FZ and subcritical heat affected zone (SCHAZ). These factors are influenced by heat input, which in turn depends upon in situ PWHT parameters.
    Matched MeSH terms: Hot Temperature
  18. Fulltext Properties of a New Insulation Material Glass Bubble in Geo-Polymer Concrete
    Shahedan NF, Abdullah MMAB, Mahmed N, Kusbiantoro A, Tammas-Williams S, Li LY, et al.
    Materials (Basel), 2021 Feb 08;14(4).
    PMID: 33567696 DOI: 10.3390/ma14040809
    This paper details analytical research results into a novel geopolymer concrete embedded with glass bubble as its thermal insulating material, fly ash as its precursor material, and a combination of sodium hydroxide (NaOH) and sodium silicate (Na2SiO3) as its alkaline activator to form a geopolymer system. The workability, density, compressive strength (per curing days), and water absorption of the sample loaded at 10% glass bubble (loading level determined to satisfy the minimum strength requirement of a load-bearing structure) were 70 mm, 2165 kg/m3, 52.58 MPa (28 days), 54.92 MPa (60 days), and 65.25 MPa (90 days), and 3.73 %, respectively. The thermal conductivity for geopolymer concrete decreased from 1.47 to 1.19 W/mK, while the thermal diffusivity decreased from 1.88 to 1.02 mm2/s due to increased specific heat from 0.96 to 1.73 MJ/m3K. The improved physicomechanical and thermal (insulating) properties resulting from embedding a glass bubble as an insulating material into geopolymer concrete resulted in a viable composite for use in the construction industry.
    Matched MeSH terms: Hot Temperature
  19. Laser-heated needle for biopsy tract ablation: In vivo study of rabbit liver biopsy
    Raziff HHA, Tan D, Tan SH, Wong YH, Lim KS, Yeong CH, et al.
    Phys Med, 2021 Feb;82:40-45.
    PMID: 33581616 DOI: 10.1016/j.ejmp.2021.01.067
    PURPOSE: To investigate the efficacy of a newly-developed laser-heated core biopsy needle in the thermal ablation of biopsy tract to reduce hemorrhage after biopsy using in vivo rabbit's liver model.

    MATERIALS AND METHODS: Five male New Zealand White rabbits weighed between 1.5 and 4.0 kg were anesthetized and their livers were exposed. 18 liver biopsies were performed under control group (without tract ablation, n = 9) and study group (with tract ablation, n = 9) settings. The needle insertion depth (~3 cm) and rate of retraction (~3 mm/s) were fixed in all the experiments. For tract ablation, three different needle temperatures (100, 120 and 150 °C) were compared. The blood loss at each biopsy site was measured by weighing the gauze pads before and after blood absorption. The rabbits were euthanized immediately and the liver specimens were stained with hematoxylin-eosin (H&E) for further histopathological examination (HPE).

    RESULTS: The average blood loss in the study group was reduced significantly (p 

    Matched MeSH terms: Hot Temperature
  20. A fully coupled multiphase model for infrared-convective drying of sweet potato
    Onwude DI, Hashim N, Chen G, Putranto A, Udoenoh NR
    J Sci Food Agric, 2021 Jan 30;101(2):398-413.
    PMID: 32627847 DOI: 10.1002/jsfa.10649
    BACKGROUND: Combined infrared (CIR) and convective drying is a promising technology in dehydrating heat-sensitive foods, such as fruits and vegetables. This novel thermal drying method, which involves the application of infrared energy and hot air during a drying process, can drastically enhance energy efficiency and improve overall product quality at the end of the process. Understanding the dynamics of what goes on inside the product during drying is important for further development, optimization, and upscaling of the drying method. In this study, a multiphase porous media model considering liquid water, gases, and solid matrix was developed for the CIR and hot-air drying (HAD) of sweet potato slices in order to capture the relevant physics and obtain an in-depth insight on the drying process. The model was simulated using Matlab with user-friendly graphical user interface for easy coupling and faster computational time.

    RESULTS: The gas pressure for CIR-HAD was higher centrally and decreased gradually towards the surface of the product. This implies that drying force is stronger at the product core than at the product surface. A phase change from liquid water to vapour occurs almost immediately after the start of the drying process for CIR-HAD. The evaporation rate, as expected, was observed to increase with increased drying time. Evaporation during CIR-HAD increased with increasing distance from the centreline of the sample surface. The simulation results of water and vapour flux revealed that moisture transport around the surfaces and sides of the sample is as a result of capillary diffusion, binary diffusion, and gas pressure in both the vertical and horizontal directions. The nonuniform dominant infrared heating caused the heterogeneous distribution of product temperature. These results suggest that CIR-HAD of food occurs in a non-uniform manner with high vapour and water concentration gradient between the product core and the surface.

    CONCLUSIONS: This study provides in-depth insight into the physics and phase changes of food during CIR-HAD. The multiphase model has the advantage that phase change and impact of CIR-HAD operating parameters can be swiftly quantified. Such a modelling approach is thereby significant for further development and process optimization of CIR-HAD towards industrial upscaling. © 2020 Society of Chemical Industry.

    Matched MeSH terms: Hot Temperature
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