Displaying publications 21 - 40 of 78 in total

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  1. Correlation data of (Z)-1-[4-(trifluoromethyl)benzylidene]thiosemicarbazide via spectroscopic methods and Density Functional Theory studies
    Osman UM, Farizal ASN, Kadir MA, Razali MH, Rozaini MZH, Arshad S
    Data Brief, 2019 Dec;27:104673.
    PMID: 31720328 DOI: 10.1016/j.dib.2019.104673
    New compound, namely (Z)-1-[4-(trifluoromethyl)benzylidene]thiosemicarbazide was successfully synthesized using thiosemicarbazide with 4-(trifluoromethyl)-benzaldehyde in ethanol solution. The data presented in this articles is related to our research articles entitled "Crystal Structure of (Z)-1-[4-(Trifluoromethyl)benzylidene]thiosemicarbazide" (Osman et al., 2017) [1]. This work shows the continue data from experimental spectroscopic measurement which are Fourier Transform Infrared (FTIR) and 13C Nuclear Magnetic Resonance (13C NMR). Assessment on the correlation with theoretical computational data was also carried out through GaussView 5.0.9 and Gaussian09 software. Molecular Electrostatic Potential (MEP) and Highest Occupied Molecular Orbital-Lowest Unoccupied Molecular Orbital (HOMO-LUMO) were also illustrated.
    Matched MeSH terms: Static Electricity
  2. Fulltext Effect of shield placement for transient voltage mitigation due to switching surges in a 33/11 kV transformer windings
    Srikanta Murthy A, Azis N, Jasni J, Othman ML, Mohd Yousof MF, Talib MA
    PLoS One, 2020;15(10):e0240368.
    PMID: 33035254 DOI: 10.1371/journal.pone.0240368
    This study presents an investigation on the effect of shield placement for mitigation of transient voltage in a 33/11 kV, 30 MVA transformer due to Standard Switching Impulse (SSI) and Oscillating Switching Impulse (OSI) surges. Generally, the winding and insulation in transformers could experience severe voltage stress due to the external impulses i.e. switching events. Hence, it is important to examine the voltage stress and identify the mitigation action i.e. shield placements in order to reduce the adverse effect to the transformer windings. First, the resistances, inductances, and capacitances (RLC) were calculated for disc type transformer in order to develop the winding RLC equivalent circuit. The SSI and OSI transient voltage waveforms were applied to the High Voltage (HV) winding whereby the transient voltages were simulated for each disc. The resulting voltage stresses were mitigated through different configurations of electrostatic shield placements. The resonant oscillations generated due to switching surges were analysed through initial voltage distribution. The analyses on the transient voltages of the transformer winding and standard error of the slope (SEb) reveal that the location of shield placement has a significant effect on the resonant switching voltages. The increment of the shield number in the windings does not guarantee optimize mitigation of the resonant switching transient voltages. It is found that the voltage stress along the windings is linear once a floating shield is placed between the HV and Low Voltage (LV) windings of the disc-type transformer under the SSI and OSI waveforms. These findings could assist the manufacturers with appropriate technical basis for mitigation of the transformer winding against the external transient switching overvoltage surges.
    Matched MeSH terms: Static Electricity
  3. Dynamic Absorption Enhancement and Equivalent Resonant Circuit Modeling of Tunable Graphene-Metal Hybrid Antenna
    Ullah Z, Nawi I, Witjaksono G, Tansu N, Khattak MI, Junaid M, et al.
    Sensors (Basel), 2020 Jun 04;20(11).
    PMID: 32512718 DOI: 10.3390/s20113187
    Plasmonic antennas are attractive optical components of the optoelectronic devices, operating in the far-infrared regime for sensing and imaging applications. However, low optical absorption hinders its potential applications, and their performance is limited due to fixed resonance frequency. In this article, a novel gate tunable graphene-metal hybrid plasmonic antenna with stacking configuration is proposed and investigated to achieve tunable performance over a broad range of frequencies with enhanced absorption characteristics. The hybrid graphene-metal antenna geometry is built up with a hexagon radiator that is supported by the Al2O3 insulator layer and graphene reflector. This stacked structure is deposited in the high resistive Si wafer substrate, and the hexagon radiator itself is a sandwich structure, which is composed of gold hexagon structure and two multilayer graphene stacks. The proposed antenna characteristics i.e., tunability of frequency, the efficiency corresponding to characteristics modes, and the tuning of absorption spectra, are evaluated by full-wave numerical simulations. Besides, the unity absorption peak that was realized through the proposed geometry is sensitive to the incident angle of TM-polarized incidence waves, which can flexibly shift the maxima of the absorption peak from 30 THz to 34 THz. Finally, an equivalent resonant circuit model for the investigated antenna based on the simulations results is designed to validate the antenna performance. Parametric analysis of the proposed antenna is carried out through altering the geometric parameters and graphene parameters in the Computer Simulation Technology (CST) studio. This clearly shows that the proposed antenna has a resonance frequency at 33 THz when the graphene sheet Fermi energy is increased to 0.3 eV by applying electrostatic gate voltage. The good agreement of the simulation and equivalent circuit model results makes the graphene-metal antenna suitable for the realization of far-infrared sensing and imaging device containing graphene antenna with enhanced performance.
    Matched MeSH terms: Static Electricity
  4. Fulltext Selective Arylation of 2-Bromo-4-chlorophenyl-2-bromobutanoate via a Pd-Catalyzed Suzuki Cross-Coupling Reaction and Its Electronic and Non-Linear Optical (NLO) Properties via DFT Studies
    Nazeer U, Rasool N, Mujahid A, Mansha A, Zubair M, Kosar N, et al.
    Molecules, 2020 Jul 31;25(15).
    PMID: 32752125 DOI: 10.3390/molecules25153521
    In the present study, 2-bromo-4-chlorophenyl-2-bromobutanoate (3) was synthesized via the reaction of 2-bromo-4-chlorophenol with 2-bromobutanoyl bromide in the presence of pyridine. A variety of 2-bromo-4-chlorophenyl-2-bromobutanoate derivatives (5a-f) were synthesized with moderate to good yields via a Pd-catalyzed Suzuki cross-coupling reaction. To find out the reactivity and electronic properties of the compounds, Frontier molecular orbital analysis, non-linear optical properties, and molecular electrostatic potential studies were performed.
    Matched MeSH terms: Static Electricity
  5. Fulltext Extraction of winding parameters for 33/11 kV, 30 MVA transformer based on finite element method for frequency response modelling
    Srikanta Murthy A, Azis N, Jasni J, Othman ML, Mohd Yousof MF, Talib MA
    PLoS One, 2020;15(8):e0236409.
    PMID: 32853253 DOI: 10.1371/journal.pone.0236409
    This paper proposes an alternative approach to extract transformer's winding parameters of resistance (R), inductance (L), capacitance (C) and conductance (G) based on Finite Element Method (FEM). The capacitance and conductance were computed based on Fast Multiple Method (FMM) and Method of Moment (MoM) through quasi-electrostatics approach. The AC resistances and inductances were computed based on MoM through quasi-magnetostatics approach. Maxwell's equations were used to compute the DC resistances and inductances. Based on the FEM computed parameters, the frequency response of the winding was obtained through the Bode plot function. The simulated frequency response by FEM model was compared with the simulated frequency response based on the Multi-conductor Transmission Line (MTL) model and the measured frequency response of a 33/11 kV, 30 MVA transformer. The statistical indices such as Root Mean Square Error (RMSE) and Absolute Sum of Logarithmic Error (ASLE) were used to analyze the performance of the proposed FEM model. It is found that the simulated frequency response by FEM model is quite close to measured frequency response at low and mid frequency regions as compared to simulated frequency response by MTL model based on RMSE and ASLE analysis.
    Matched MeSH terms: Static Electricity
  6. Fulltext One Pot Selective Arylation of 2-Bromo-5-Chloro Thiophene; Molecular Structure Investigation via Density Functional Theory (DFT), X-ray Analysis, and Their Biological Activities
    Rasool N, Kanwal A, Rasheed T, Ain Q, Mahmood T, Ayub K, et al.
    Int J Mol Sci, 2016;17(7).
    PMID: 27367666 DOI: 10.3390/ijms17070912
    Synthesis of 2,5-bisarylthiophenes was accomplished by sequential Suzuki cross coupling reaction of 2-bromo-5-chloro thiophenes. Density functional theory (DFT) studies were carried out at the B3LYP/6-31G(d, p) level of theory to compare the geometric parameters of 2,5-bisarylthiophenes with those from X-ray diffraction results. The synthesized compounds are screened for in vitro bacteria scavenging abilities. At the concentration of 50 and 100 μg/mL, compounds 2b, 2c, 2d, 3c, and 3f with IC50-values of 51.4, 52.10, 58.0, 56.2, and 56.5 μg/mL respectively, were found most potent against E. coli. Among all the synthesized compounds 2a, 2d, 3c, and 3e with the least values of IC50 77, 76.26, 79.13 μg/mL respectively showed significant antioxidant activities. Almost all of the compounds showed good antibacterial activity against Escherichia coli, whereas 2-chloro-5-(4-methoxyphenyl) thiophene (2b) was found most active among all synthesized compound with an IC50 value of 51.4 μg/mL. All of the synthesized compounds were screened for nitric oxide scavenging activity as well. Frontier molecular orbitals (FMOs) and molecular electrostatic potentials of the target compounds were also studied theoretically to account for their relative reactivity.
    Matched MeSH terms: Static Electricity
  7. Transient electro-magneto-hydrodynamic two-phase blood flow and thermal transport through a capillary vessel
    Mirza IA, Abdulhameed M, Vieru D, Shafie S
    Comput Methods Programs Biomed, 2016 Dec;137:149-166.
    PMID: 28110721 DOI: 10.1016/j.cmpb.2016.09.014
    Therapies with magnetic/electromagnetic field are employed to relieve pains or, to accelerate flow of blood-particles, particularly during the surgery. In this paper, a theoretical study of the blood flow along with particles suspension through capillary was made by the electro-magneto-hydrodynamic approach. Analytical solutions to the non-dimensional blood velocity and non-dimensional particles velocity are obtained by means of the Laplace transform with respect to the time variable and the finite Hankel transform with respect to the radial coordinate. The study of thermally transfer characteristics is based on the energy equation for two-phase thermal transport of blood and particles suspension with viscous dissipation, the volumetric heat generation due to Joule heating effect and electromagnetic couple effect. The solution of the nonlinear heat transfer problem is derived by using the velocity field and the integral transform method. The influence of dimensionless system parameters like the electrokinetic width, the Hartman number, Prandtl number, the coefficient of heat generation due to Joule heating and Eckert number on the velocity and temperature fields was studied using the Mathcad software. Results are presented by graphical illustrations.
    Matched MeSH terms: Static Electricity
  8. A bio-based, facile approach for the preparation of covalently functionalized carbon nanotubes aqueous suspensions and their potential as heat transfer fluids
    Sadri R, Hosseini M, Kazi SN, Bagheri S, Zubir N, Solangi KH, et al.
    J Colloid Interface Sci, 2017 Oct 15;504:115-123.
    PMID: 28531649 DOI: 10.1016/j.jcis.2017.03.051
    In this study, we propose an innovative, bio-based, environmentally friendly approach for the covalent functionalization of multi-walled carbon nanotubes using clove buds. This approach is innovative because we do not use toxic and hazardous acids which are typically used in common carbon nanomaterial functionalization procedures. The MWCNTs are functionalized in one pot using a free radical grafting reaction. The clove-functionalized MWCNTs (CMWCNTs) are then dispersed in distilled water (DI water), producing a highly stable CMWCNT aqueous suspension. The CMWCNTs are characterized using Raman spectroscopy, X-ray photoelectron spectroscopy and transmission electron microscopy. The electrostatic interactions between the CMWCNT colloidal particles in DI water are verified via zeta potential measurements. UV-vis spectroscopy is also used to examine the stability of the CMWCNTs in the base fluid. The thermo-physical properties of the CMWCNT nano-fluids are examined experimentally and indeed, this nano-fluid shows remarkably improved thermo-physical properties, indicating its superb potential for various thermal applications.
    Matched MeSH terms: Static Electricity
  9. Fulltext Carbon Based Polymeric Nanocomposites for Dye Adsorption: Synthesis, Characterization, and Application
    Ali Khan M, Govindasamy R, Ahmad A, Siddiqui MR, Alshareef SA, Hakami AAH, et al.
    Polymers (Basel), 2021 Jan 28;13(3).
    PMID: 33525497 DOI: 10.3390/polym13030419
    Agglomeration and restacking can reduce graphene oxide (GO) activity in a wide range of applications. Herein, GO was synthesized by a modified Hummer's method. To minimize restacking and agglomeration, in situ chemical oxidation polymerization was carried out to embed polyaniline (PANI) chains at the edges of GO sheets, to obtain GO-PANI nanocomposite. The GO-PANI was tested for the adsorptive removal of brilliant green (BG) from an aqueous solution through batch mode studies. Infrared (FT-IR) analysis revealed the dominance of hydroxyl and carboxylic functionalities over the GO-PANI surface. Solution pH-dependent BG uptake was observed, with maximum adsorption at pH 7, and attaining equilibrium in 30 min. The adsorption of BG onto GO-PANI was fit to the Langmuir isotherm, and pseudo-second-order kinetic models, with a maximum monolayer adsorption capacity (qm) of 142.8 mg/g. An endothermic adsorption process was observed. Mechanistically, π-π stacking interaction and electrostatic interaction played a critical role during BG adsorption on GO-PANI.
    Matched MeSH terms: Static Electricity
  10. Fulltext Investigation on the use of graphene oxide as novel surfactant to stabilize weakly charged graphene nanoplatelets
    Kazi SN, Badarudin A, Zubir MN, Ming HN, Misran M, Sadeghinezhad E, et al.
    Nanoscale Res Lett, 2015;10:212.
    PMID: 25995712 DOI: 10.1186/s11671-015-0882-7
    This paper presents a unique synergistic behavior between a graphene oxide (GO) and graphene nanoplatelet (GnP) composite in an aqueous medium. The results showed that GO stabilized GnP colloid near its isoelectric point and prevented rapid agglomeration and sedimentation. It was considered that a rarely encountered charge-dependent electrostatic interaction between the highly charged GO and weakly charged GnP particles kept GnP suspended at its rapid coagulation and phase separation pH. Sedimentation and transmission electron microscope (TEM) micrograph images revealed the evidence of highly stable colloidal mixtures while zeta potential measurement provided semi-quantitative explanation on the mechanism of stabilization. GnP suspension was confirmed via UV-vis spectral data while contact angle measurement elucidated the close resemblance to an aqueous solution indicating the ability of GO to mediate the flocculation prone GnP colloids. About a tenfold increase in viscosity was recorded at a low shear rate in comparison to an individual GO solution due to a strong interaction manifested between participating colloids. An optimum level of mixing ratio between the two constituents was also obtained. These new findings related to an interaction between charge-based graphitic carbon materials would open new avenues for further exploration on the enhancement of both GO and GnP functionalities particularly in mechanical and electrical domains.
    Matched MeSH terms: Static Electricity
  11. A new thio-Schiff base fluorophore with copper ion sensing, DNA binding and nuclease activity
    Vikneswaran R, Syafiq MS, Eltayeb NE, Kamaruddin MN, Ramesh S, Yahya R
    Spectrochim Acta A Mol Biomol Spectrosc, 2015 Nov 5;150:175-80.
    PMID: 26046495 DOI: 10.1016/j.saa.2015.05.087
    Copper ion recognition and DNA interaction of a newly synthesized fluorescent Schiff base (HPyETSC) were investigated using UV-vis and fluorescent spectroscopy. Examination using these two techniques revealed that the detection of copper by HPyETSC is highly sensitive and selective, with a detection limit of 0.39 μm and the mode of interaction between HPyETSC and DNA is electrostatic, with a binding constant of 8.97×10(4) M(-1). Furthermore, gel electrophoresis studies showed that HPyETSC exhibited nuclease activity through oxidative pathway.
    Matched MeSH terms: Static Electricity
  12. FT-IR, NBO, HOMO-LUMO, MEP analysis and molecular docking study of Methyl N-({[2-(2-methoxyacetamido)-4-(phenylsulfanyl)phenyl]amino}[(methoxycarbonyl) imino]methyl)carbamate
    Panicker CY, Varghese HT, Narayana B, Divya K, Sarojini BK, War JA, et al.
    Spectrochim Acta A Mol Biomol Spectrosc, 2015 Sep 5;148:29-42.
    PMID: 25863457 DOI: 10.1016/j.saa.2015.03.064
    The optimized molecular structure, vibrational frequencies, corresponding vibrational assignments of Methyl N-({[2-(2-methoxyacetamido)-4-(phenylsulfanyl) phenyl]amino} [(methoxycarbonyl)imino]methyl)carbamate have been investigated using HF and DFT levels of calculations. The geometrical parameters are in agreement with XRD data. The stability of the molecule arising from hyper-conjugative interaction and charge delocalization has been analyzed using NBO analysis. The HOMO and LUMO analysis is used to determine the charge transfer within the molecule. Molecular electrostatic potential study was also performed. The first and second hyperpolarizability was calculated in order to find its role in nonlinear optics. Molecular docking studies are also reported. Prediction of Activity Spectra analysis of the title compound predicts anthelmintic and antiparasitic activity as the most probable activity with Pa (probability to be active) value of 0.808 and 0.797, respectively. Molecular docking studies show that both the phenyl groups and the carbonyl oxygens of the molecule are crucial for bonding and these results draw us to the conclusion that the compound might exhibit pteridine reductase inhibitory activity.
    Matched MeSH terms: Static Electricity
  13. Unraveling Bacterial Single-Stranded Sequence Specificities: Insights from Molecular Dynamics and MMPBSA Analysis of Oligonucleotide Probes
    Pirojsirikul T, Lee VS, Nimmanpipug P
    Mol Biotechnol, 2024 Apr;66(4):582-591.
    PMID: 38374320 DOI: 10.1007/s12033-024-01082-0
    We utilized molecular dynamics (MD) simulations and Molecular Mechanics Poisson-Boltzmann Surface Area (MMPBSA) free energy calculations to investigate the specificity of two oligonucleotide probes, namely probe B and probe D, in detecting single-stranded DNA (ssDNA) within three bacteria families: Enterobacteriaceae, Pasteurellaceae, and Vibrionaceae. Due to the limited understanding of molecular mechanisms in the previous research, we have extended the discussion to focus specifically on investigating the binding process of bacteria-probe DNA duplexes, with an emphasis on analyzing the binding free energy. The role of electrostatic contributions in the specificity between the oligonucleotide probes and the bacterial ssDNAs was investigated and found to be crucial. Our calculations yielded results that were highly consistent with the experimental data. Through our study, we have successfully exhibited the benefits of utilizing in-silico approaches as a powerful virtual-screening tool, particularly in research areas that demand a thorough comprehension of molecular interactions.
    Matched MeSH terms: Static Electricity
  14. Molecular dynamics simulations suggest changes in electrostatic interactions as a potential mechanism through which serine phosphorylation inhibits DNA polymerase β activity
    Homouz D, Joyce-Tan KH, ShahirShamsir M, Moustafa IM, Idriss HT
    J Mol Graph Model, 2018 09;84:236-241.
    PMID: 30138833 DOI: 10.1016/j.jmgm.2018.08.007
    DNA polymerase β is a 39 kDa enzyme that is a major component of Base Excision Repair in human cells. The enzyme comprises two major domains, a 31 kDa domain responsible for the polymerase activity and an 8 kDa domain, which bind ssDNA and has a deoxyribose phosphate (dRP) lyase activity. DNA polymerase β was shown to be phosphorylated in vitro with protein kinase C (PKC) at serines 44 and 55 (S44 and S55), resulting in loss of its polymerase enzymic activity, but not its ability to bind ssDNA. In this study, we investigate the potential phosphorylation-induced structural changes for DNA polymerase β using molecular dynamics simulations. The simulations show drastic conformational changes of the polymerase structure as a result of S44 phosphorylation. Phosphorylation-induced conformational changes transform the closed (active) enzyme structure into an open one. Further analysis of the results points to a key hydrogen bond and newly formed salt bridges as potential drivers of these structural fluctuations. The changes observed with S55/44 and S55 phosphorylation were less dramatic and the integrity of the H-bond was not compromised. Thus the phosphorylation of S44 is the major contributor to structural fluctuations that lead to loss of enzymatic activity.
    Matched MeSH terms: Static Electricity*
  15. Precisely controlled electrostatically sprayed sodium alginate/carboxymethyl chitosan hydrogel microbeads as super-adsorbent for adsorption of cationic dye
    Li X, Tiang MF, Cui X, Li Y, Wang Z, Zhao L, et al.
    Int J Biol Macromol, 2024 Dec;283(Pt 4):137989.
    PMID: 39581417 DOI: 10.1016/j.ijbiomac.2024.137989
    In this pioneering study, electrostatic spraying (ES) technology with high voltages is proposed to reduce the size of hydrogel microbeads further, aiming to enhance the adsorption rate of cationic methylene blue (MB) dye. The increased voltages, ranging from 0.0 to 13.0 kV, further decreased the size of electrostatically sprayed hydrogel microbeads crosslinked by hydrogen bonds between sodium alginate (SA) and carboxymethyl chitosan (CMCS) in hydrochloric acid. The size of SA/CMCS hydrogel microbeads was successfully reduced from 2000 ± 121 μm (SC-2000) to 400 ± 15 μm (SC-400). Notably, SC-400 exhibits the highest maximum adsorption capacity (qm) and rate constant (k2) at 840.3 mg/g and 0.0598 g/mg/min, respectively, at pH 9.0 and a temperature of 25 °C in the absence of ionic compounds, which is three times higher than that of SC-2000, due to their high specific surface area and pore volume. Through a series of adsorption studies and characterization analyses, SA/CMCS hydrogel microbeads displayed heterogeneous adsorption behaviors towards MB dye through electrostatic interactions between the deprotonated carboxylic groups and cationic MB molecules, where MB adsorption efficiency could be significantly influenced by pH and ionic strength. These findings suggest that ES technology is effective in synthesizing smaller SA/CMCS hydrogel microbeads with enhanced MB removal rates and stable adsorption capacities and their applications could be further explored for removing other organic dyes and toxic metals in subsequent research studies.
    Matched MeSH terms: Static Electricity*
  16. Fulltext Silver Nanoparticles in the Water Environment in Malaysia: Inspection, characterization, removal, modeling, and future perspective
    Syafiuddin A, Salmiati S, Hadibarata T, Kueh ABH, Salim MR, Zaini MAA
    Sci Rep, 2018 01 17;8(1):986.
    PMID: 29343711 DOI: 10.1038/s41598-018-19375-1
    The current status of silver nanoparticles (AgNPs) in the water environment in Malaysia was examined and reported. For inspection, two rivers and two sewage treatment plants (STPs) were selected. Two activated carbons derived from oil palm (ACfOPS) and coconut (ACfCS) shells were proposed as the adsorbent to remove AgNPs. It was found that the concentrations of AgNPs in the rivers and STPs are in the ranges of 0.13 to 10.16 mg L-1 and 0.13 to 20.02 mg L-1, respectively, with the highest concentration measured in July. ACfOPS and ACfCS removed up to 99.6 and 99.9% of AgNPs, respectively, from the water. The interaction mechanism between AgNPs and the activated carbon surface employed in this work was mainly the electrostatic force interaction via binding Ag+ with O- presented in the activated carbon to form AgO. Fifteen kinetic models were compared statistically to describe the removal of AgNPs. It was found that the experimental adsorption data can be best described using the mixed 1,2-order model. Therefore, this model has the potential to be a candidate for a general model to describe AgNPs adsorption using numerous materials, its validation of which has been confirmed with other material data from previous works.
    Matched MeSH terms: Static Electricity
  17. Physical properties and stability evaluation of fish oil-in-water emulsions stabilized using thiol-modified β-lactoglobulin fibrils-chitosan complex
    Chang HW, Tan TB, Tan PY, Abas F, Lai OM, Wang Y, et al.
    Food Res Int, 2018 03;105:482-491.
    PMID: 29433239 DOI: 10.1016/j.foodres.2017.11.034
    Fish oil-in-water emulsions containing fish oil, thiol-modified β-lactoglobulin (β-LG) fibrils, chitosan and maltodextrin were fabricated using a high-energy method. The results showed that chitosan coating induced charge reversal; denoting successful biopolymers complexation. A significantly (p<0.05) larger droplet size and lower polydispersity index value, attributed to the thicker chitosan coating at the oil-water interface, were observed. At high chitosan concentrations, the cationic nature of chitosan strengthened the electrostatic repulsion between the droplets, thus conferring high oxidative stability and low turbidity loss rate to the emulsions. The apparent viscosity of emulsions stabilized using thiol-modified β-LG fibrils-chitosan complex was higher than those stabilized using β-LG fibrils alone, resulting in the former's higher creaming stability. Under thermal treatments (63°C and 100°C), emulsions stabilized using thiol-modified β-LG fibrils-chitosan complex possessed higher heat stability as indicated by the consistent droplet sizes observed. Chitosan provided a thicker protective layer that protected the oil droplets against high temperature. Bridging flocculation occurred at low chitosan concentration (0.1%, w/w), as revealed through microscopic observations which indicated the presence of large flocs. All in all, this work provided us with a better understanding of the application of protein fibrils-polysaccharide complex to produce stable emulsion.
    Matched MeSH terms: Static Electricity
  18. QSAR and Pharmacophore Mapping Studies on Benzothiazinimines to Relate their Structural Features with anti-HIV Activity
    Geethaavacini G, Poh GP, Yan LY, Deepashini R, Shalini S, Harish R, et al.
    Med Chem, 2018;14(7):733-740.
    PMID: 29807521 DOI: 10.2174/1573406414666180529091618
    BACKGROUND: The development of severe drug resistance caused by the extensive use of anti-HIV agents has resulted in a greatly extensive reduction in these drugs efficacy.

    OBJECTIVES: To identify the important pharmacophoric features and correlate 3D chemical structure of benzothiazinimines with their anti-HIV potential using 2D, 3D-QSAR and pharmacophore modeling studies.

    METHODS: QSAR and pharmacophore mapping studies have been used to relate structural features. 2D QSAR and 3D QSAR studies were performed using partial least square and k-nearest neighbor methodology, coupled with various feature selection methods, viz. stepwise, genetic algorithm, and simulated annealing, to derive QSAR models which were further validated for statistical significance.

    RESULTS: The physicochemical descriptor XAHydrophilicArea and SsOHE-index, and alignmentindependent descriptor T_C_Cl_6 showed significant correlation with the anti-HIV activity of benzothiazinimines in 2D QSAR. 3D QSAR results showed the significant effect of electrostatic and steric field descriptors in the anti-HIV potential of benzothiazinimines. The generated pharmacophore hypothesis demonstrated the importance of aromaticity and hydrogen bond acceptors.

    CONCLUSION: The significant models obtained in this study suggested that these techniques could be used as a guidance for designing new benzothiazinimines with enhanced anti-HIV potential.

    Matched MeSH terms: Static Electricity
  19. Interaction of monomeric Ebola VP40 protein with a plasma membrane: A coarse-grained molecular dynamics (CGMD) simulation study
    Mohamad Yusoff MA, Abdul Hamid AA, Mohammad Bunori N, Abd Halim KB
    J Mol Graph Model, 2018 Jun;82:137-144.
    PMID: 29730487 DOI: 10.1016/j.jmgm.2018.04.010
    Ebola virus is a lipid-enveloped filamentous virus that affects human and non-human primates and consists of several types of protein: nucleoprotein, VP30, VP35, L protein, VP40, VP24, and transmembrane glycoprotein. Among the Ebola virus proteins, its matrix protein VP40 is abundantly expressed during infection and plays a number of critical roles in oligomerization, budding and egress from the host cell. VP40 exists predominantly as a monomer at the inner leaflet of the plasma membrane, and has been suggested to interact with negatively charged lipids such as phosphatidylinositol 4,5-bisphosphate (PIP2) and phosphatidylserine (PS) via its cationic patch. The hydrophobic loop at the C-terminal domain has also been shown to be important in the interaction between the VP40 and the membrane. However, details of the molecular mechanisms underpinning their interactions are not fully understood. This study aimed at investigating the effects of mutation in the cationic patch and hydrophobic loop on the interaction between the VP40 monomer and the plasma membrane using coarse-grained molecular dynamics simulation (CGMD). Our simulations revealed that the interaction between VP40 and the plasma membrane is mediated by the cationic patch residues. This led to the clustering of PIP2 around the protein in the inner leaflet as a result of interactions between some cationic residues including R52, K127, K221, K224, K225, K256, K270, K274, K275 and K279 and PIP2 lipids via electrostatic interactions. Mutation of the cationic patch or hydrophobic loop amino acids caused the protein to bind at the inner leaflet of the plasma membrane in a different orientation, where no significant clustering of PIP2 was observed around the mutated protein. This study provides basic understanding of the interaction of the VP40 monomer and its mutants with the plasma membrane.
    Matched MeSH terms: Static Electricity
  20. Cleaning potential of surfactin on fouled ultrafiltration (UF) membranes
    Mohd Hafez Mohd Isa, Frazier AR, Jauregi P
    Sains Malaysiana, 2012;41:1117-1124.
    Biosurfactants are microbially produced surface active agents that offer better biodegradability and lower toxicity than chemically synthesized surfactants because of their biogenetic origin. One of the most surface-active biosurfactants known is surfactin, a cyclic lipopeptide produced by various strains of Bacillus subtilis. In this study, the cleaning potential of surfactin on ultrafiltration (UF) membranes fouled with BSA was studied using centrifugal UF devices of 50 kDa and 100 kDa MWCO polyethersulfone (PES) membranes. Mechanisms of bovine serum albumin (BSA) displacement by surfactin on fouled UF membranes were studied using dynamic light scattering (DLS) technique and surface tension measurements. Hydrodynamic diameter and surface tension measurements of BSA-surfactin mixtures showed that the surfactin was efficient in displacing BSA fouled on UF membranes due to strong electrostatic repulsive interactions involved at pH8.5. This study demonstrated that surfactin can be used to effectively clean fouled UF membranes.
    Matched MeSH terms: Static Electricity
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