Displaying publications 41 - 60 of 387 in total

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  1. Ooi PS, Engelhard G
    J Appl Meas, 2019;20(1):79-99.
    PMID: 30789834
    The fairness of raters in music performance assessment has become an important concern in the field of music. The assessment of students' music performance depends in a fundamental way on rater judgements. The quality of rater judgements is crucial to provide fair, meaningful and informative assessments of music performance. There are many external factors that can influence the quality of rater judgements. Previous research has used different measurement models to examine the quality of rater judgements (e.g., generalizability theory). There are limitations with the previous analysis methods that are based on classical test theory and its extensions. In this study, we use modern measurement theory (Rasch measurement theory) to examine the quality of rater judgements. The many-facets Rasch rating scale model is employed to investigate the extent of rater-invariant measurement in the context of music performance assessments related to university degrees in Malaysia (159 students rated by 24 raters). We examine the rating scale structure, the severity levels of the raters, and the judged difficulty of the items. We also examine the interaction effects across musical instrument subgroups (keyboard, strings, woodwinds, brass, percussions and vocal). The results suggest that there were differences in severity levels among the raters. The results of this study also suggest that raters had different severity levels when rating different musical instrument subgroups. The implications for research, theory and practice in the assessment of music performance are included in this paper.
    Matched MeSH terms: Copper
  2. Lah NAC, Trigueros S
    Sci Technol Adv Mater, 2019;20(1):225-261.
    PMID: 30956731 DOI: 10.1080/14686996.2019.1585145
    The recent interest to nanotechnology aims not only at device miniaturisation, but also at understanding the effects of quantised structure in materials of reduced dimensions, which exhibit different properties from their bulk counterparts. In particular, quantised metal nanowires made of silver, gold or copper have attracted much attention owing to their unique intrinsic and extrinsic length-dependent mechanical properties. Here we review the current state of art and developments in these nanowires from synthesis to mechanical properties, which make them leading contenders for next-generation nanoelectromechanical systems. We also present theories of interatomic interaction in metallic nanowires, as well as challenges in their synthesis and simulation.
    Matched MeSH terms: Copper
  3. Md Razak Daud, Wan Nor Shela Ezwane Wan Jusoh, Syahrullail Samion
    MyJurnal
    This study investigates metal removal rate (MRR) of the biomaterial by using discharge machine Neuar CNC A50 Electrical Discharge Machine Die Sinking (EDM DS). The purpose of this study is to compare machining curvature cup for material SKD 11 and stainless steel with shape curvature cup acetabular. The result showed that electrode wear is higher when high current is applied. For each applied current 0.5A and 3.0A could result electrode wear of 0.236 mm, 0.246 mm and 0.269 mm respectively. Mean time of complete discharged for each pit with 0.3mm depth with supply 0. 5A is 6.51 minutes; 1. 5A is 3.54 minutes and 3A is 1.52 minutes. The biggest mean parameter of the pit is 0.356 mm, with 3A of current is applied. From this study, it can be concluded that low current set may give lower electrode copper wear. The experiment will help a researcher to discharge biomaterial types of metal with small size of copper electrode use of EDM DS Neuar for discharge multi hole or micro pit.
    Matched MeSH terms: Copper
  4. Ho MC, Wu TY
    Bioresour Technol, 2020 Apr;301:122684.
    PMID: 31954964 DOI: 10.1016/j.biortech.2019.122684
    In this study, a novel Type II deep eutectic solvent (DES) namely, choline chloride:copper(II) chloride dihydrate (ChCl:CuCl2·2H2O) was used to pretreat oil palm fronds (OPFs). The sequential pretreatment with alkaline hydrogen peroxide (0.25 vol%, 90 min) at ambient conditions and a Type II DES (90 °C, 3 h) at a later stage resulted in a delignification of 55.14% with high xylan (80.79%) and arabinan (98.02%) removals. The characterizations of pretreated OPFs confirmed the excellent performance of DES in OPF fractionation. Thus, the application of a Type II DES at ambient pressure and relatively lower temperature was able to improve the lignin and hemicellulose removals from OPFs.
    Matched MeSH terms: Copper
  5. Paracha KN, Butt AD, Alghamdi AS, Babale SA, Soh PJ
    Sensors (Basel), 2019 Dec 28;20(1).
    PMID: 31905646 DOI: 10.3390/s20010177
    This work reviews design aspects of liquid metal antennas and their corresponding applications. In the age of modern wireless communication technologies, adaptability and versatility have become highly attractive features of any communication device. Compared to traditional conductors like copper, the flow property and lack of elasticity limit of conductive fluids, makes them an ideal alternative for applications demanding mechanically flexible antennas. These fluidic properties also allow innovative antenna fabrication techniques like 3D printing, injecting, or spraying the conductive fluid on rigid/flexible substrates. Such fluids can also be easily manipulated to implement reconfigurability in liquid antennas using methods like micro pumping or electrochemically controlled capillary action as compared to traditional approaches like high-frequency switching. In this work, we discuss attributes of widely used conductive fluids, their novel patterning/fabrication techniques, and their corresponding state-of-the-art applications.
    Matched MeSH terms: Copper
  6. Low QJ, Siaw C, Lee RA, Cheo SW
    QJM, 2020 Sep 01;113(9):693-694.
    PMID: 31917404 DOI: 10.1093/qjmed/hcaa005
    Matched MeSH terms: Copper
  7. van der Ent A, Echevarria G, Nkrumah PN, Erskine PD
    Ann Bot, 2020 10 30;126(6):1017-1027.
    PMID: 32597938 DOI: 10.1093/aob/mcaa119
    BACKGROUND AND AIMS: The aim of this study was to test the frequency distributions of foliar elements from a large dataset from Kinabalu Park (Sabah, Malaysia) for departure from unimodality, indicative of a distinct ecophysiological response associated with hyperaccumulation.

    METHODS: We collected foliar samples (n = 1533) comprising 90 families, 198 genera and 495 plant species from ultramafic soils, further foliar samples (n = 177) comprising 45 families, 80 genera and 120 species from non-ultramafic soils and corresponding soil samples (n = 393 from ultramafic soils and n = 66 from non-ultramafic soils) from Kinabalu Park (Sabah, Malaysia). The data were geographically (Kinabalu Park) and edaphically (ultramafic soils) constrained. The inclusion of a relatively high proportion (approx. 14 %) of samples from hyperaccumulator species [with foliar concentrations of aluminium and nickel (Ni) >1000 μg g-1, cobalt, copper, chromium and zinc >300 μg g-1 or manganese (Mn) >10 mg g-1] allowed for hypothesis testing.

    KEY RESULTS: Frequency distribution graphs for most elements [calcium (Ca), magnesium (Mg) and phosphorus (P)] were unimodal, although some were skewed left (Mg and Mn). The Ni frequency distribution was bimodal and the separation point for the two modes was between 250 and 850 μg g-1.

    CONCLUSIONS: Accounting for statistical probability, the established empirical threshold value (>1000 μg g-1) remains appropriate. The two discrete modes for Ni indicate ecophysiologically distinct behaviour in plants growing in similar soils. This response is in contrast to Mn, which forms the tail of a continuous (approximately log-normal) distribution, suggestive of an extension of normal physiological processes.

    Matched MeSH terms: Copper
  8. Alam A, Islam SS, Islam MH, Almutairi AF, Islam MT
    Materials (Basel), 2020 Jun 04;13(11).
    PMID: 32512784 DOI: 10.3390/ma13112560
    This paper presents an ultra-wideband metamaterial absorber for solar harvesting in the infrared regime (220-360 THz) of the solar spectrum. The proposed absorber consists of square-shaped copper patches of different sizes imposed on a GaAs (Gallium arsenide) substrate. The design and simulation of the unit cell are performed with finite integration technique (FIT)-based simulation software. Scattering parameters are retrieved during the simulation process. The constructed design offers absorbance above 90% within a 37.89% relative bandwidth and 99.99% absorption over a vast portion of the investigated frequency range. An equivalent circuit model is presented to endorse the validity of the proposed structure. The calculated result strongly agrees with the simulated result. Symmetrical construction of the proposed unit cell reports an angular insensitivity up to a 35° oblique incidence. Post-processed simulation data confirm that the design is polarization-insensitive.
    Matched MeSH terms: Copper
  9. Gurdeep Singh HK, Yusup S, Quitain AT, Abdullah B, Ameen M, Sasaki M, et al.
    Environ Res, 2020 07;186:109616.
    PMID: 32668556 DOI: 10.1016/j.envres.2020.109616
    Catalytic cracking of vegetable oil mainly processed over zeolites, and among all the zeolites particularly HZMS-5 has been investigated on wide range for renewable and clean gasoline production from various plant oils. Despite the fact that HZSM-5 offers a higher conversion degree and boost aromatics yield, the isomerate yield reduces due to high cracking activity and shape selectivity of HZSM-5. Hence, to overcome these problems, in this study the transition metals, such as nickel and copper doped over HZSM-5 were tested for its efficiencies to improve the isoparaffin compounds. The catalysts were screened with linoleic acid in a catalytic cracking reaction conducted at 450 ᵒC for 90 min in an atmospheric condition in batch reactor. Then, the gasoline composition of the organic liquid product (OLP) was analysed in terms of paraffin, isoparaffin, olefin, naphthenes and aromatics (PIONA). The results showed that Cu/ZSM-5 produced the highest liquid yield of 79.1%, at the same time reduced the production of gas and coke to 18.8% and 0.7%. Furthermore, the desired isoparaffin composition in biogasoline increased from 1.6% to 6.8% and at the same time reduced the oxygenated and aromatic compounds to 15.4% and 59.7%, respectively. The linoleic acid as model compound of rubber seed oil, in the catalytic cracking reaction provides a clearer understanding of the process. Besides, the water gas shift (WGS) reaction in catalytic cracking reaction provides insitu hydrogen production to saturate the branched olefin into the desired isoparaffin and the aromatics into naphthenes.
    Matched MeSH terms: Copper
  10. Munir M, Ahmad M, Rehan M, Saeed M, Lam SS, Nizami AS, et al.
    Environ Res, 2021 02;193:110398.
    PMID: 33127396 DOI: 10.1016/j.envres.2020.110398
    This study focused on producing high quality and yield of biodiesel from novel non-edible seed oil of abundantly available wild Raphnus raphanistrum L. using an efficient, recyclable and eco-friendly copper modified montmorillonite (MMT) clay catalyst. The maximum biodiesel yield of 83% was obtained by base catalyzed transesterification process under optimum operating conditions of methanol to oil ratio of 15:1, reaction temperature of 150 °C, reaction time of 5 h and catalyst loading of 3.5%. The synthesized catalyst and biodiesel were characterized for their structural features and chemical compositions using various state-of-the-art techniques, including x-ray diffraction, scanning electron microscopy, energy dispersive x-ray spectroscopy, Fourier transform infrared spectroscopy, nuclear magnetic resonance (1H, 13C) and gas chromatography-mass spectroscopy. The fuel properties of the biodiesel were estimated including kinematic viscosity (4.36 cSt), density (0.8312 kg/L), flash point (72 °C), acid value (0.172 mgKOH/g) and sulphur content (0.0002 wt.%). These properties were compared and found in good agreement with the International Biodiesel Standards of American (ASTM-951, 6751), European Committee (EN-14214) and China GB/T 20828 (2007). The catalyst was re-used in five consecutive transesterification reactions without losing much catalytic efficiency. Overall, non-edible Raphnus raphanistrum L.. seed oil and Cu doped MMT clay catalyst appeared to be highly active, stable, and cheap contenders for future biofuel industry. However, detailed life cycle assessment (LCA) studies of Raphnus raphanistrum L. seed oil biodiesel are highly recommended to assess the technical, ecological, social and economic challenges.
    Matched MeSH terms: Copper
  11. Mohd Amirul Syafiq Mohd Yunos, Zainal Abidin Talib, Wan Mahmood Mat Yunus, Liew, Josephine Ying Chyi, Paulus, Wilfred Sylvester
    MyJurnal
    Semiconductor thin films Copper Tin Selenide, Cu2SnSe3, a potential compound for solar cell applications or semiconductor radiation detector were prepared by thermal evaporation method onto well-cleaned glass substrates. The as-deposited films were annealed in flowing purified nitrogen N2, for 2 hours in a temperature range from 100˚C to 500˚C. The structure of as-deposited and annealed films has been studied by X-ray diffraction technique. The semi-quantitative analysis indicated from Reitveld refinement show that the samples composed of Cu2SnSe3 and SnSe. These studies revealed that the films were structured in mixed phase between cubic space group F-43m (no. 216) and orthorhombic space group P n m a (no. 62). The crystallite size and lattice strain were determined from Scherrer calculation method. The results show that increasing in annealing temperature resulted in direct increase in crystallite size and decrease in lattice strain.
    Matched MeSH terms: Copper
  12. Khoo, Hock-Eng, Azrina Azlan, Mohd Aizat Idris, Amin Ismail, Muhammad Rizal Razman
    MyJurnal
    The present study was carried out to determine the concentrations of selected metal elements (lead, copper, manganese, zinc and iron) in 51 samples of commercial drinking water and tap water available in Malaysia. The results indicated that low metal elements were found in the studied water samples. Lead, manganese, zinc and iron were not detected in some of the studied samples, except copper. The concentrations of the metal elements in the studied samples were well below the maximum permitted concentrations as recommended. Therefore these drinking water are safe for consumption and do not pose adverse effect to the health of consumers due to metal toxicity.
    Matched MeSH terms: Copper
  13. Abd Aziz MA, Md Isa K, Ab Rashid R
    Waste Manag Res, 2017 Jun;35(6):647-655.
    PMID: 28431479 DOI: 10.1177/0734242X17697815
    This article aims to provide insights into the factors that contribute to the separation efficiency of solid particles. In this study, a pneumatic jigging technique was used to assess the separation of solid waste materials that consisted of copper, glass and rubber insulator. Several initial experiments were carried out to evaluate the strengths and limitations of the technique. It is found that despite some limitations of the technique, all the samples prepared for the experiments were successfully separated. The follow-up experiments were then carried out to further assess the separation of copper wire and rubber insulator. The effects of air flow and pulse rates on the separation process were examined. The data for these follow-up experiments were analysed using a sink float analysis technique. The analysis shows that the air flow rate was very important in determining the separation efficiency. However, the separation efficiency may be influenced by the type of materials used.
    Matched MeSH terms: Copper
  14. Velmurugan S, C-K Yang T, Ching Juan J, Chen JN
    J Colloid Interface Sci, 2021 Aug 15;596:108-118.
    PMID: 33838324 DOI: 10.1016/j.jcis.2021.03.083
    Herein this research, a visible light active tungsten oxide/copper manganate (WO3/CuMnO2) p-n heterojunction nanocomposite was prepared and has been applied for a signal on photoelectrochemical sensing of antibiotic nitrofurazone (NFZ). Firstly, the n-WO3 nanotiles were synthesized from the cetrimonium bromide (CTAB) assisted hydrothermal method and the p-CuMnO2 nanoparticles were synthesized by using the ultrasound-assisted hydrothermal method. The photoelectrochemical NFZ sensing performance of WO3/CuMnO2 nanocomposite was 1.9 times higher than that of as-synthesized pure WO3 nanotiles. The resulting higher photoelectrochemical performance of the nanocomposite is due to more visible light absorption ability and synergy from p-n heterojunction formation. The designed WO3/CuMnO2 nanocomposite sensor gives satisfactory photocurrent signals for the detection of NFZ in the range of 0.015-32 μM with the detection limit (LOD) of 1.19 nM. The practical applicability of the nanocomposite sensor was monitored in pork liver and tap water samples.
    Matched MeSH terms: Copper
  15. Misron N, Harun NH, Lee YK, Sidek RM, Aris I, Wakiwaka H, et al.
    Sensors (Basel), 2014;14(2):2431-48.
    PMID: 24496313 DOI: 10.3390/s140202431
    Among palm oil millers, the ripeness of oil palm Fresh Fruit Bunch (FFB) is determined through visual inspection. To increase the productivity of the millers, many researchers have proposed with a new detection method to replace the conventional one. The sensitivity of such a sensor plays a crucial role in determining the effectiveness of the method. In our preliminary study a novel oil palm fruit sensor to detect the maturity of oil palm fruit bunches is proposed. The design of the proposed air coil sensor based on an inductive sensor is further investigated to improve its sensitivity. This paper investigates the results pertaining to the effects of the air coil structure of an oil palm fruit sensor, taking consideration of the used copper wire diameter ranging from 0.10 mm to 0.18 mm with 60 turns. The flat-type shape of air coil was used on twenty samples of fruitlets from two categories, namely ripe and unripe. Samples are tested with frequencies ranging from 20 Hz to 120 MHz. The sensitivity of the sensor between air to fruitlet samples increases as the coil diameter increases. As for the sensitivity differences between ripe and unripe samples, the 5 mm air coil length with the 0.12 mm coil diameter provides the highest percentage difference between samples and it is amongst the highest deviation value between samples. The result from this study is important to improve the sensitivity of the inductive oil palm fruit sensor mainly with regards to the design of the air coil structure. The efficiency of the sensor to determine the maturity of the oil palm FFB and the ripening process of the fruitlet could further be enhanced.
    Matched MeSH terms: Copper
  16. Mohammad Haniff MA, Muhammad Hafiz S, Wahid KA, Endut Z, Wah Lee H, Bien DC, et al.
    Sci Rep, 2015;5:14751.
    PMID: 26423893 DOI: 10.1038/srep14751
    In this work, the piezoresistive effects of defective graphene used on a flexible pressure sensor are demonstrated. The graphene used was deposited at substrate temperatures of 750, 850 and 1000 °C using the hot-filament thermal chemical vapor deposition method in which the resultant graphene had different defect densities. Incorporation of the graphene as the sensing materials in sensor device showed that a linear variation in the resistance change with the applied gas pressure was obtained in the range of 0 to 50 kPa. The deposition temperature of the graphene deposited on copper foil using this technique was shown to be capable of tuning the sensitivity of the flexible graphene-based pressure sensor. We found that the sensor performance is strongly dominated by the defect density in the graphene, where graphene with the highest defect density deposited at 750 °C exhibited an almost four-fold sensitivity as compared to that deposited at 1000 °C. This effect is believed to have been contributed by the scattering of charge carriers in the graphene networks through various forms such as from the defects in the graphene lattice itself, tunneling between graphene islands, and tunneling between defect-like structures.
    Matched MeSH terms: Copper
  17. Khalik WF, Ho LN, Ong SA, Lai NB, Thor SH, Yap KL
    Environ Sci Pollut Res Int, 2023 Apr;30(20):58516-58526.
    PMID: 36988807 DOI: 10.1007/s11356-023-26589-y
    Cathode in photocatalytic fuel cell (PFC) plays a crucial role in degradation of organic contaminants. In this study, synthesized copper oxide (CuO) was loaded on carbon plate and used as photocathode in PFC for degradation of synthetic azo dye Reactive Black 5 (RB5) and real textile wastewater. Morphology and structural phase of the synthesized CuO were analyzed using scanning electron microscopy (SEM) and X-ray diffraction (XRD), respectively. Several operating parameters had been investigated such as light irradiation, initial dye concentration, and pH of azo dye solution within 6 h of irradiation time. The lowest initial concentration of RB5 (10 mg L-1) achieved 100% color removal compared to the highest initial concentration (40 mg L-1) which only achieved 77.1% color removal within 6 h of irradiation time. The influence of external resistance was significant in electricity generation but trivial in dye degradation efficiency. The external resistance of 6000 Ω yielded highest maximum power density, with Pmax of 0.2631 μW cm-2, followed by 1000 Ω (0.2196 μW cm-2) and 8000 Ω (0.1587 μW cm-2), respectively. The real textile wastewater with dilution ratio (DR) 1:6 yielded the highest energy conversion efficiency, η (3.62%), followed by DR 1:4 (3.19%) and DR 1:2 (1.96%), respectively.
    Matched MeSH terms: Copper
  18. Sahari NS, Shahir S, Ibrahim Z, Hasmoni SH, Altowayti WAH
    Environ Sci Pollut Res Int, 2023 Nov;30(51):110069-110078.
    PMID: 37814051 DOI: 10.1007/s11356-023-30067-w
    This review discusses the application of bacterial nanocellulose (BNC) and modified BNC in treating wastewater containing heavy metals and dye contaminants. It also highlights the challenges and future perspectives of BNC and its composites. Untreated industrial effluents containing toxic heavy metals are systematically discharged into public waters. In particular, lead (Pb), copper (Cu), cadmium (Cd), nickel (Ni), zinc (Zn), and arsenic (As) are very harmful to human health and, in some cases, may lead to death. Several methods such as chemical precipitation, ion exchange, membrane filtration, coagulation, and Fenton oxidation are used to remove these heavy metals from the environment. However, these methods involve the use of numerous chemicals whilst producing high amount of toxic sludge. Meanwhile, the development of the adsorption-based technique has provided an alternative way of treating wastewater using BNC. Bacterial nanocellulose requires less energy for purification and has higher purity than plant cellulose. In general, the optimum growth parameters are crucial in BNC production. Even though native BNC can be used for the removal of heavy metals and dyes, the incorporation of other materials, such as polyethyleneimine, graphene oxide, calcium carbonate and polydopamine can improve sorption efficiencies.
    Matched MeSH terms: Copper
  19. Agi A, Junin R, Rasol M, Gbadamosi A, Gunaji R
    PLoS One, 2018;13(8):e0200595.
    PMID: 30089104 DOI: 10.1371/journal.pone.0200595
    Treated Rhizopora mucronata tannin (RMT) as a corrosion inhibitor for carbon steel and copper in oil and gas facilities was investigated. Corrosion rate of carbon-steel and copper in 3wt% NaCl solution by RMT was studied using chemical (weight loss method) and spectroscopic (FTIR) techniques at various temperatures in the ranges of 26-90°C. The weight loss data was compared to the electrochemical by the application of Faraday's law for the conversion of corrosion rate data from one system to another. The inhibitive efficiency of RMT was compared with commercial inhibitor sodium benzotriazole (BTA-S). The best concentration of RMT was 20% (w/v), increase in concentration of RMT decreased the corrosion rate and increased the inhibitive efficiency. Increase in temperature increased the corrosion rate and decreased the inhibitive efficiency but, the rate of corrosion was mild with RMT. The FTIR result shows the presence of hydroxyl group, aromatic group, esters and the substituted benzene group indicating the purity of the tannin. The trend of RMT was similar to that of BTA-S, but its inhibitive efficiency for carbon-steel was poor (6%) compared to RMT (59%). BTA-S was efficient for copper (76%) compared to RMT (74%) at 40% (w/v) and 20% (w/v) concentration respectively. RMT was efficient even at low concentration therefore, the use of RMT as a cost effective and environmentally friendly corrosion inhibiting agent for carbon steel and copper is herein proposed.
    Matched MeSH terms: Copper/chemistry
  20. Yousif E, Ahmed DS, Ahmed A, Abdallh M, Yusop RM, Mohammed SA
    Environ Sci Pollut Res Int, 2019 Sep;26(25):26381-26388.
    PMID: 31290046 DOI: 10.1007/s11356-019-05784-w
    A new Schiff base containing 1,2,4-triazole ring system (L) was synthesized and confirmed by 1HNMR, FTIR spectroscopy. The chemical modification of PVC with a new Schiff base (L) was synthesized to produce a homogenous blend (PVC-L). A homogenous blend (PVC-L) was added to copper chloride to produce PVC-L-Cu (II). The PVC films had been irradiated with ultraviolet light for a long period and confirmed by FTIR spectroscopy and weight loss; the surface morphology was inspected by scanning electron microscopy.
    Matched MeSH terms: Copper/chemistry
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