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Molecular docking of compounds from Clinacanthus nutans extract detected by GC-MS analysis with the SARS-CoV-2 main protease and ACE2 protein

Ismail NZ, Adebayo IA, Mohamad Zain NN, Arsad H

Nat Prod Res, 2021 May 05.
PMID: 33949277 DOI: 10.1080/14786419.2021.1919104

Clinacanthus nutans has been reported to have many medicinal properties and it is traditionally used in treating viral lesions. This study aims to determine the molecular docking of C. nutans compounds detected by Gas Chromatography-Mass Spectrometry (GC-MS) with the novel severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2 main protease) protein and its host receptor angiotensin-converting enzyme 2 (ACE2) protein using the AutoDock 4.2 tool. The drug-likeness and molecular docking analyses showed that fourteen compounds of C. nutans satisfied the Lipinski's rule of five and they exhibited good inhibitory effects against the SARS-Cov-2 main protease and ACE2 proteins. In addition, the glyceryl 2-linolenate compound was found to have the most potent binding affinities with both proteins. The results provide useful insights into the molecular inhibitory interactions of C. nutans compounds detected by GC-MS analysis with the targeted SARS-CoV-2 main protease and ACE2 protein.

Matched MeSH terms: Physical Phenomena; Biophysical Phenomena
Comparison analysis on scaling the vertical and lateral NMOSFET in nanometer regime

Ismail Saad, Razali Ismail, Ima Sulaiman

Sains Malaysiana, 2008;37:233-237.

Conventional lateral and vertical n-channel MOS transistors with channel length in the range of 100nm to 50nm have been systematically investigated by means of device simulation. The comparison analysis includes critical parameters that govern device performance. Threshold voltage VT roll-off, leakage current Ioff, drain saturation current IDsat and sub-threshold swing S were analyze and compared between the device. Due to double gate (DG) structure over the side of silicon pillar a better electrostatics potential control of channel is obtained in vertical device shown by an analysis on VT roll-off. A two decade higher of Ioff in planar device is observed with Lg=50nm. A factor of three times larger IDsat is observed for vertical MOSFETs compared to planar device. The sub-threshold swing S remains almost the same when the Lg larger than 80 nm. It increased rapidly when the Lg is scaled down to 50 nm due to the short channel effect SCE. However, the vertical device has a steady increase whereas the planar device has suffered immediate enhance of SCE. The analysis results confirmed that vertical MOSFET with double-gate structure is a potential solution to overcome SCE when scaled the channel length to 50nm and beyond.

Matched MeSH terms: Physical Phenomena
Fulltext The influence of lightning induced voltage on the distribution power line polymer insulators

Izadi M, Abd Rahman MS, Ab-Kadir MZ, Gomes C, Jasni J, Hajikhani M

PLoS One, 2017;12(2):e0172118.
PMID: 28234930 DOI: 10.1371/journal.pone.0172118

Protection of medium voltage (MV) overhead lines against the indirect effects of lightning is an important issue in Malaysia and other tropical countries. Protection of these lines against the indirect effects of lightning is a major concern and can be improved by several ways. The choice of insulator to be used for instance, between the glass, ceramic or polymer, can help to improve the line performance from the perspective of increasing the breakdown strength. In this paper, the electrical performance of a 10 kV polymer insulator under different conditions for impulse, weather and insulator angle with respect to a cross-arm were studied (both experimental and modelling) and the results were discussed accordingly. Results show that the weather and insulator angle (with respect to the cross-arm) are surprisingly influenced the values of breakdown voltage and leakage current for both negative and positive impulses. Therefore, in order to select a proper protection system for MV lines against lightning induced voltage, consideration of the local information concerning the weather and also the insulator angles with respect to the cross-arm are very useful for line stability and performance.

Matched MeSH terms: Physical Phenomena
Fulltext Population pharmacokinetic meta-analysis of individual data to design the first randomized efficacy trial of vancomycin in neonates and young infants

Jacqz-Aigrain E, Leroux S, Thomson AH, Allegaert K, Capparelli EV, Biran V, et al.

J Antimicrob Chemother, 2019 08 01;74(8):2128-2138.
PMID: 31049551 DOI: 10.1093/jac/dkz158

OBJECTIVES: In the absence of consensus, the present meta-analysis was performed to determine an optimal dosing regimen of vancomycin for neonates.
METHODS: A 'meta-model' with 4894 concentrations from 1631 neonates was built using NONMEM, and Monte Carlo simulations were performed to design an optimal intermittent infusion, aiming to reach a target AUC0-24 of 400 mg·h/L at steady-state in at least 80% of neonates.
RESULTS: A two-compartment model best fitted the data. Current weight, postmenstrual age (PMA) and serum creatinine were the significant covariates for CL. After model validation, simulations showed that a loading dose (25 mg/kg) and a maintenance dose (15 mg/kg q12h if <35 weeks PMA and 15 mg/kg q8h if ≥35 weeks PMA) achieved the AUC0-24 target earlier than a standard 'Blue Book' dosage regimen in >89% of the treated patients.
CONCLUSIONS: The results of a population meta-analysis of vancomycin data have been used to develop a new dosing regimen for neonatal use and to assist in the design of the model-based, multinational European trial, NeoVanc.

Matched MeSH terms: Physical Phenomena
Fulltext Multiphasic Reaction Modeling for Polypropylene Production in a Pilot-Scale Catalytic Reactor

Jakir Hossain Khan M, Azlan Hussain M, Mujtaba IM

Polymers (Basel), 2016 Jun 14;8(6).
PMID: 30979325 DOI: 10.3390/polym8060220

In this study, a novel multiphasic model for the calculation of the polypropylene production in a complicated hydrodynamic and the physiochemical environments has been formulated, confirmed and validated. This is a first research attempt that describes the development of the dual-phasic phenomena, the impact of the optimal process conditions on the production rate of polypropylene and the fluidized bed dynamic details which could be concurrently obtained after solving the model coupled with the CFD (computational fluid dynamics) model, the basic mathematical model and the moment equations. Furthermore, we have established the quantitative relationship between the operational condition and the dynamic gas⁻solid behavior in actual reaction environments. Our results state that the proposed model could be applied for generalizing the production rate of the polymer from a chemical procedure to pilot-scale chemical reaction engineering. However, it was assumed that the solids present in the bubble phase and the reactant gas present in the emulsion phase improved the multiphasic model, thus taking into account that the polymerization took place mutually in the emulsion besides the bubble phase. It was observed that with respect to the experimental extent of the superficial gas velocity and the Ziegler-Natta feed rate, the ratio of the polymer produced as compared to the overall rate of production was approximately in the range of 9%⁻11%. This is a significant amount and it should not be ignored. We also carried out the simulation studies for comparing the data of the CFD-dependent dual-phasic model, the emulsion phase model, the dynamic bubble model and the experimental results. It was noted that the improved dual-phasic model and the CFD model were able to predict more constricted and safer windows at similar conditions as compared to the experimental results. Our work is unique, as the integrated developed model is able to offer clearer ideas related to the dynamic bed parameters for the separate phases and is also capable of computing the chemical reaction rate for every phase in the reaction. Our improved mutiphasic model revealed similar dynamic behaviour as the conventional model in the initial stages of the polymerization reaction; however, it diverged as time progressed.

Matched MeSH terms: Physical Phenomena
Fulltext Partial Purification and Characterisation of Pectinase Produced by Aspergillus niger LFP-1 Grown on Pomelo Peels as a Substrate

Jalil MTM, Ibrahim D

Trop Life Sci Res, 2021 Mar;32(1):1-22.
PMID: 33936548 DOI: 10.21315/tlsr2021.32.1.1

In the present study, pectinase was produced by local fungal isolate, Aspergillus niger LFP-1 grown on pomelo peels as a sole carbon source under solid-state fermentation (SSF). The purification process begins with the concentration of crude enzyme using ammonium sulfate precipitation and followed by purification using anion-exchange column chromatography (DEAE-Sephadex) and subsequently using gel filtration column chromatography (Sephadex G-100). On the other hand, the molecular weight of the purified enzyme was determined through SDS-PAGE. The findings revealed the crude enzyme was purified up to 75.89 folds with a specific activity of 61.54 U/mg and the final yield obtained was 0.01%. The molecular mass of the purified pectinase was 48 kDa. The optimum pH and temperature were 3.5 and 50°C, respectively. This enzyme was stable at a range of pH 3.5 to 4.5 and a relatively high temperature (40°C-50°C) for 100 min. The Km and Vmax were found to be 3.89 mg/mL and 1701 U/mg, respectively. Meanwhile, pectin from citrus fruit and the metal ion (Co2+) were the best substrate and inducer to enhance pectinase yield, respectively.

Matched MeSH terms: Physical Phenomena
Fulltext Crystal structure of 2'-hy-droxy-aceto-phenone 4-methyl-thio-semicarbazide

Jamsari J, Abas NF, Ravoof TB, Tiekink ER

Acta Crystallogr E Crystallogr Commun, 2015 Apr 1;71(Pt 4):o244-5.
PMID: 26029436 DOI: 10.1107/S2056989015004958

In the organic mol-ecule of the title hydrate, C11H15N3OS·H2O, {systematic name: 3-ethyl-1-{(E)-[1-(2-hy-droxy-phen-yl)ethyl-idene]amino}-thio-urea monohydrate}, a dihedral angle of 5.39 (2)° is formed between the hy-droxy-benzene ring and the non-H atoms comprising the side chain (r.m.s. deviation = 0.0625 Å), with the major deviation from planarity noted for the terminal ethyl group [the C-N-C-C torsion angle = -172.17 (13)°]. The N-H H atoms are syn and an intra-molecular hy-droxy-imine O-H⋯N hydrogen bond is noted. In the crystal, the N-bonded H atoms form hydrogen bonds to symmetry-related water mol-ecules, and the latter form donor inter-actions with the hy-droxy O atom and with a hy-droxy-benzene ring, forming a O-H⋯π inter-action. The hydrogen bonding leads to supra-molecular tubes aligned along the b axis. The tubes are connected into layers via C-H⋯O inter-actions, and these stack along the c axis with no directional inter-actions between them.

Matched MeSH terms: Physical Phenomena
Fulltext Investigating Master-Slave Architecture for Underwater Wireless Sensor Network

Jan S, Yafi E, Hafeez A, Khatana HW, Hussain S, Akhtar R, et al.

Sensors (Basel), 2021 Apr 25;21(9).
PMID: 33922886 DOI: 10.3390/s21093000

A significant increase has been observed in the use of Underwater Wireless Sensor Networks (UWSNs) over the last few decades. However, there exist several associated challenges with UWSNs, mainly due to the nodes' mobility, increased propagation delay, limited bandwidth, packet duplication, void holes, and Doppler/multi-path effects. To address these challenges, we propose a protocol named "An Efficient Routing Protocol based on Master-Slave Architecture for Underwater Wireless Sensor Network (ERPMSA-UWSN)" that significantly contributes to optimizing energy consumption and data packet's long-term survival. We adopt an innovative approach based on the master-slave architecture, which results in limiting the forwarders of the data packet by restricting the transmission through master nodes only. In this protocol, we suppress nodes from data packet reception except the master nodes. We perform extensive simulation and demonstrate that our proposed protocol is delay-tolerant and energy-efficient. We achieve an improvement of 13% on energy tax and 4.8% on Packet Delivery Ratio (PDR), over the state-of-the-art protocol.

Matched MeSH terms: Physical Phenomena
Determination of potential curves of Br2 in Franck-Condon's region

Janic ES, Butigan V, Novakovic JD, Lekic M

Sains Malaysiana, 2014;43:637-642.

The extinction of Br2 molecules in gas state is measured for different wavelengths of incident light in interval of 370 - 570 nm by method of gas spectroscopy. The measurement is made on the basis of Franck-Condon's principle, under which a transition to a more excited state is done without changing the intercore distance (in further text, R). The graph of energy dependence on extinction is drawn. On the graph are recognized two Gausses slopes and their separation (deconvolution) is done. The complete Gausses functions are determined on graph. The method of mirror symmetry is applied on Gausses slopes of extinction and symmetrical extinction values (Es) are obtained. Borders of Franck-Condon's area are determined from ground state of Linear Harmonic Oscillator (LH0). Tables of dependence on R and the excitation energy are given. On the basis of these tables are drawn potential curves of electron energy E(R) in excited electronic states of Br2 molecules as functions of R in Franck-Condon's area.

Matched MeSH terms: Physical Phenomena
Fulltext Energy-Efficient Wireless Sensor Networks for Precision Agriculture: A Review

Jawad HM, Nordin R, Gharghan SK, Jawad AM, Ismail M

Sensors (Basel), 2017 Aug 03;17(8).
PMID: 28771214 DOI: 10.3390/s17081781

Wireless sensor networks (WSNs) can be used in agriculture to provide farmers with a large amount of information. Precision agriculture (PA) is a management strategy that employs information technology to improve quality and production. Utilizing wireless sensor technologies and management tools can lead to a highly effective, green agriculture. Based on PA management, the same routine to a crop regardless of site environments can be avoided. From several perspectives, field management can improve PA, including the provision of adequate nutrients for crops and the wastage of pesticides for the effective control of weeds, pests, and diseases. This review outlines the recent applications of WSNs in agriculture research as well as classifies and compares various wireless communication protocols, the taxonomy of energy-efficient and energy harvesting techniques for WSNs that can be used in agricultural monitoring systems, and comparison between early research works on agriculture-based WSNs. The challenges and limitations of WSNs in the agricultural domain are explored, and several power reduction and agricultural management techniques for long-term monitoring are highlighted. These approaches may also increase the number of opportunities for processing Internet of Things (IoT) data.

Matched MeSH terms: Physical Phenomena*
Fulltext Hard rock landforms generate 130 km ice shelf channels through water focusing in basal corrugations

Jeofry H, Ross N, Le Brocq A, Graham AGC, Li J, Gogineni P, et al.

Nat Commun, 2018 11 01;9(1):4576.
PMID: 30385741 DOI: 10.1038/s41467-018-06679-z

Satellite imagery reveals flowstripes on Foundation Ice Stream parallel to ice flow, and meandering features on the ice-shelf that cross-cut ice flow and are thought to be formed by water exiting a well-organised subglacial system. Here, ice-penetrating radar data show flow-parallel hard-bed landforms beneath the grounded ice, and channels incised upwards into the ice shelf beneath meandering surface channels. As the ice transitions to flotation, the ice shelf incorporates a corrugation resulting from the landforms. Radar reveals the presence of subglacial water alongside the landforms, indicating a well-organised drainage system in which water exits the ice sheet as a point source, mixes with cavity water and incises upwards into a corrugation peak, accentuating the corrugation downstream. Hard-bedded landforms influence both subglacial hydrology and ice-shelf structure and, as they are known to be widespread on formerly glaciated terrain, their influence on the ice-sheet-shelf transition could be more widespread than thought previously.

Matched MeSH terms: Physical Phenomena
Fulltext Microstructural behavior of magnetorheological elastomer undergoing durability evaluation by stress relaxation

Johari MAF, Mazlan SA, Nasef MM, Ubaidillah U, Nordin NA, Aziz SAA, et al.

Sci Rep, 2021 May 25;11(1):10936.
PMID: 34035434 DOI: 10.1038/s41598-021-90484-0

The widespread use of magnetorheological elastomer (MRE) materials in various applications has yet to be limited due to the fact that there are substantial deficiencies in current experimental and theoretical research on its microstructural durability behavior. In this study, MRE composed of silicon rubber (SR) and 70 wt% of micron-sized carbonyl iron particles (CIP) was prepared and subjected to stress relaxation evaluation by torsional shear load. The microstructure and particle distribution of the obtained MRE was evaluated by a field emission scanning electron microscopy (FESEM). The influence of constant low strain at 0.01% is the continuing concern within the linear viscoelastic (LVE) region of MRE. Stress relaxation plays a significant role in the life cycle of MRE and revealed that storage modulus was reduced by 8.7%, normal force has weakened by 27%, and stress performance was reduced by 6.88% along approximately 84,000 s test duration time. This time scale was the longest ever reported being undertaken in the MRE stress relaxation study. Novel micro-mechanisms that responsible for the depleted performance of MRE was obtained by microstructurally observation using FESEM and in-phase mode of atomic force microscope (AFM). Attempts have been made to correlate strain localization produced by stress relaxation, with molecular deformation in MRE amorphous matrix. Exceptional attention was focused on the development of molecular slippage, disentanglement, microplasticity, microphase separation, and shear bands. The relation between these microstructural phenomena and the viscoelastic properties of MRE was diffusely defined and discussed. The presented MRE is homogeneous with uniform distribution of CIP. The most significant recent developments of systematic correlation between the effects of microstructural deformation and durability performance of MRE under stress relaxation has been observed and evaluated.

Matched MeSH terms: Physical Phenomena
Evaluation of Alkylamine Modified Pt Nanoparticles as Oxygen Reduction Reaction Electrocatalyst for Fuel Cells via Electrochemical Impedance Spectroscopy

Joshi P, Okada T, Miyabayashi K, Miyake M

Anal Chem, 2018 May 15;90(10):6116-6123.
PMID: 29613775 DOI: 10.1021/acs.analchem.8b00247

Organically (octyl amine, OA) surface modified electrocatalyst (OA-Pt/CB) was studied for its oxygen reduction reaction (ORR) activity via dc methods and its charge and mass transfer properties were studied via electrochemical impedance spectroscopy (EIS). Comparison with a commercial catalyst (TEC10V30E) with similar Pt content was also carried out. In EIS, both the catalysts showed a single time-constant with an emerging high-frequency semicircle of very small diameter which was fitted using suitable equivalent circuits. The organically modified catalyst showed lower charge-transfer resistance and hence, low polarization resistance in high potential region as compared to the commercial catalyst. The dominance of kinetic processes was observed at 0.925-1.000 V, whereas domination of diffusion based processes was observed at lower potential region for the organic catalyst. No effect due to the presence of carbon was observed in the EIS spectra. Using the hydrodynamic method, higher current penetration depth was obtained for the organically modified catalyst at 1600 rpm. Exchange current density and Tafel slopes for both the electrocatalysts were calculated from the polarization resistance obtained from EIS which was in correlation with the results obtained from dc methods.

Matched MeSH terms: Physical Phenomena
Fulltext A monoclinic polymorph of 4-(2H-1,3-benzodioxol-5-yl)-1-(4-methyl-phen-yl)-1H-pyrazol-5-amine

Jotani MM, Gajera NN, Patel MC, Sung HH, Tiekink ER

Acta Crystallogr E Crystallogr Commun, 2015 Oct 1;71(Pt 10):1121-4.
PMID: 26594387 DOI: 10.1107/S2056989015016023

The title compound, C17H15N3O2, is a monoclinic polymorph (P21/c with Z' = 1) of the previously reported triclinic (P-1 with Z' = 2) form [Gajera et al. (2013 ▸). Acta Cryst. E69, o736-o737]. The mol-ecule in the monoclinic polymorph features a central pyrazolyl ring with an N-bound p-tolyl group and a C-bound 1,3-benzodioxolyl fused-ring system on either side of the C atom bearing the amino group. The dihedral angles between the central ring and the N- and C-bound rings are 50.06 (5) and 27.27 (5)°, respectively. The angle between the pendent rings is 77.31 (4)°, indicating the mol-ecule has a twisted conformation. The five-membered dioxolyl ring has an envelope conformation with the methyl-ene C atom being the flap. The relative disposition of the amino and dioxolyl substituents is syn. One of the independent mol-ecules in the triclinic form has a similar syn disposition but the other has an anti arrangement of these substituents. In the crystal structure of the monoclinic form, mol-ecules assemble into supra-molecular helical chains via amino-pyrazolyl N-H⋯N hydrogen bonds. These are linked into layers via C-H⋯π inter-actions, and layers stack along the a axis with no specific inter-actions between them.

Matched MeSH terms: Physical Phenomena; Biophysical Phenomena
1-Chloro-4-[2-(4-chloro-phen-yl)eth-yl]benzene and its bromo analogue: crystal structure, Hirshfeld surface analysis and computational chemistry

Jotani MM, Lee SM, Lo KM, Tiekink ERT

Acta Crystallogr E Crystallogr Commun, 2019 May 01;75(Pt 5):624-631.
PMID: 31110800 DOI: 10.1107/S2056989019004742

The crystal and mol-ecular structures of C14H12Cl2, (I), and C14H12Br2, (II), are described. The asymmetric unit of (I) comprises two independent mol-ecules, A and B, each disposed about a centre of inversion. Each mol-ecule approximates mirror symmetry [the Cb-Cb-Ce-Ce torsion angles = -83.46 (19) and 95.17 (17)° for A, and -83.7 (2) and 94.75 (19)° for B; b = benzene and e = ethyl-ene]. By contrast, the mol-ecule in (II) is twisted, as seen in the dihedral angle of 59.29 (11)° between the benzene rings cf. 0° in (I). The mol-ecular packing of (I) features benzene-C-H⋯π(benzene) and Cl⋯Cl contacts that lead to an open three-dimensional (3D) architecture that enables twofold 3D-3D inter-penetration. The presence of benzene-C-H⋯π(benzene) and Br⋯Br contacts in the crystal of (II) consolidate the 3D architecture. The analysis of the calculated Hirshfeld surfaces confirm the influence of the benzene-C-H⋯π(benzene) and X⋯X contacts on the mol-ecular packing and show that, to a first approximation, H⋯H, C⋯H/H⋯C and C⋯X/X⋯C contacts dominate the packing, each contributing about 30% to the overall surface in each of (I) and (II). The analysis also clearly differentiates between the A and B mol-ecules of (I).

Matched MeSH terms: Physical Phenomena
Fulltext Processing and Characterisation of Banana Leaf Fibre Reinforced Thermoplastic Cassava Starch Composites

Jumaidin R, Diah NA, Ilyas RA, Alamjuri RH, Yusof FAM

Polymers (Basel), 2021 Apr 28;13(9).
PMID: 33924842 DOI: 10.3390/polym13091420

Increasing environmental concerns have led to greater attention to the development of biodegradable materials. The aim of this paper is to investigate the effect of banana leaf fibre (BLF) on the thermal and mechanical properties of thermoplastic cassava starch (TPCS). The biocomposites were prepared by incorporating 10 to 50 wt.% BLF into the TPCS matrix. The samples were characterised for their thermal and mechanical properties. The results showed that there were significant increments in the tensile and flexural properties of the materials, with the highest strength and modulus values obtained at 40 wt.% BLF content. Thermogravimetric analysis showed that the addition of BLF had increased the thermal stability of the material, indicated by higher-onset decomposition temperature and ash content. Morphological studies through scanning electron microscopy (SEM) exhibited a homogenous distribution of fibres and matrix with good adhesion, which is crucial in improving the mechanical properties of biocomposites. This was also attributed to the strong interaction of intermolecular hydrogen bonds between TPCS and fibre, proven by the FT-IR test that observed the presence of O-H bonding in the biocomposite.

Matched MeSH terms: Physical Phenomena
Fulltext Computational analysis of fluid flow past a bluff body at low Reynolds number in different apex angle

Jusoh, M.Z.M., Nur Ain, A.R, Muhammad Wafi Md Nor

ESTEEM Academic Journal, 2020;16(2):65-74.
MyJurnal

A computational fluid dynamic analysis (CFD) is presented in the study of low Reynolds number fluid flow moving past bluff bodies. The study is focusing on the understanding of the effects of the apex-angles orientation on the flow structure and related occurring force. The apex-angle both facing upstream and downstream were computationally investigated. The simulation results of the cylinder solid are compared with available experimental data to justify the results and the model used. Results obtained in the present work were Strouhal number, drag coefficient, and Fast Fourier Transform (FFT). The study had found that the value of the drag force is increasing directly proportional to the apex angle. In contrast, the value of Strouhal number inversely proportional to the increasing of the apex angle. This was due to the flow over a cylinder creating a vortex shedding in the wake region which influenced the flow separation of fluid. Through the changing on orientation of the apex angle, it was also found that the characteristic linear dimension of the geometry will also be changed, thus affecting the flow pattern.

Matched MeSH terms: Physical Phenomena
Casimir force control with optical kerr effect

KHOO Y, RAYMOND OOI C

Sains Malaysiana, 2013;42:1799-1803.

The control of the Casimir force between two parallel plates can be achieved through inducing the optical Kerr effect of a nonlinear material. By considering a two-plate system which consists of a dispersive metamaterial and a nonlinear material, we show that the Casimir force between the plates can be switched between attractive and repulsive Casimir force by varying the intensity of a laser pulse. The switching sensitivity increases as the separation between plate decreases, thus providing new possibilities of controlling Casimir force for nanoelectromechanical systems.

Matched MeSH terms: Physical Phenomena
Fulltext Influence of inclined wall self-shading strategy on office building heat gain and energy performance in hot humid climate of Malaysia

Kandar MZ, Nimlyat PS, Abdullahi MG, Dodo YA

Heliyon, 2019 Jul;5(7):e02077.
PMID: 31360788 DOI: 10.1016/j.heliyon.2019.e02077

External shading geometry on buildings has been found to contribute substantially to reducing energy consumption for cooling. This study examines the effect of inclined wall self-shading strategy on heat gain in an office building. Field measurement of environmental variables such as ambient temperature, relative humidity, dew point, and wet bulb temperature was carried out in a case study inclined wall self-shading office building located in Putrajaya, Malaysia. The results of the validation of ApacheSim simulation software tool against the measured environmental variables indicated significant reliability having Pearson correlations ranging from 0.56 to 0.90. In establishing the relationship between different inclined wall strategies to the amount of heat gain, modification of the inclined wall self-shading projection (SSP) was modelled and experimented using ApacheSim simulation. Findings from the analysis revealed a relationship between heat gains into a building space and self-shading projection (SSP), as heat gains tend to reduce with increased SSP. From the findings, the optimum inclination angle of self-shading for effective heat gain reduction is based on a 45% self-shading projection. The application of inclined wall self-shading strategy in buildings would, therefore, bring about a reduction in heat gain, which invariably reduces energy consumption for cooling.

Matched MeSH terms: Physical Phenomena
Fulltext On the Utilization of Pozzolanic Wastes as an Alternative Resource of Cement

Karim MR, Hossain MM, Khan MNN, Zain MFM, Jamil M, Lai FC

Materials (Basel), 2014 Dec 05;7(12):7809-7827.
PMID: 28788277 DOI: 10.3390/ma7127809

Recently, as a supplement of cement, the utilization of pozzolanic materials in cement and concrete manufacturing has increased significantly. This study investigates the scope to use pozzolanic wastes (slag, palm oil fuel ash and rice husk ash) as an alkali activated binder (AAB) that can be used as an alternative to cement. To activate these materials, sodium hydroxide solution was used at 1.0, 2.5 and 5.0 molar concentration added into the mortar, separately. The required solution was used to maintain the flow of mortar at 110% ± 5%. The consistency and setting time of the AAB-paste were determined. Mortar was tested for its flow, compressive strength, porosity, water absorption and thermal resistance (heating at 700 °C) and investigated by scanning electron microscopy. The experimental results reveal that AAB-mortar exhibits less flow than that of ordinary Portland cement (OPC). Surprisingly, AAB-mortars (with 2.5 molar solution) achieved a compressive strength of 34.3 MPa at 28 days, while OPC shows that of 43.9 MPa under the same conditions. Although water absorption and porosity of the AAB-mortar are slightly high, it shows excellent thermal resistance compared to OPC. Therefore, based on the test results, it can be concluded that in the presence of a chemical activator, the aforementioned pozzolans can be used as an alternative material for cement.

Matched MeSH terms: Physical Phenomena

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