Displaying publications 21 - 40 of 85 in total

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  1. Cyanobacterial aldehyde deformylating oxygenase: Structure, function, and potential in biofuels production
    Basri RS, Rahman RNZRA, Kamarudin NHA, Ali MSM
    Int J Biol Macromol, 2020 Dec 01;164:3155-3162.
    PMID: 32841666 DOI: 10.1016/j.ijbiomac.2020.08.162
    The conversion of aldehydes to valuable alkanes via cyanobacterial aldehyde deformylating oxygenase is of great interest. The availability of fossil reserves that keep on decreasing due to human exploitation is worrying, and even more troubling is the combustion emission from the fuel, which contributes to the environmental crisis and health issues. Hence, it is crucial to use a renewable and eco-friendly alternative that yields compound with the closest features as conventional petroleum-based fuel, and that can be used in biofuels production. Cyanobacterial aldehyde deformylating oxygenase (ADO) is a metal-dependent enzyme with an α-helical structure that contains di‑iron at the active site. The substrate enters the active site of every ADO through a hydrophobic channel. This enzyme exhibits catalytic activity toward converting Cn aldehyde to Cn-1 alkane and formate as a co-product. These cyanobacterial enzymes are small and easy to manipulate. Currently, ADOs are broadly studied and engineered for improving their enzymatic activity and substrate specificity for better alkane production. This review provides a summary of recent progress in the study of the structure and function of ADO, structural-based engineering of the enzyme, and highlight its potential in producing biofuels.
    Matched MeSH terms: Silicon Dioxide/chemistry*
  2. Detection of Salmonella bacterium in drinking water using microring resonator
    Bahadoran M, Noorden AF, Mohajer FS, Abd Mubin MH, Chaudhary K, Jalil MA, et al.
    Artif Cells Nanomed Biotechnol, 2016;44(1):315-21.
    PMID: 25133457 DOI: 10.3109/21691401.2014.948549
    A new microring resonator system is proposed for the detection of the Salmonella bacterium in drinking water, which is made up of SiO2-TiO2 waveguide embedded inside thin film layer of the flagellin. The change in refractive index due to the binding of the Salmonella bacterium with flagellin layer causes a shift in the output signal wavelength and the variation in through and drop port's intensities, which leads to the detection of Salmonella bacterium in drinking water. The sensitivity of proposed sensor for detecting of Salmonella bacterium in water solution is 149 nm/RIU and the limit of detection is 7 × 10(-4)RIU.
    Matched MeSH terms: Silicon Dioxide/chemistry
  3. Fulltext Development of p-y curves of laterally loaded piles in cohesionless soil
    Khari M, Kassim KA, Adnan A
    ScientificWorldJournal, 2014;2014:917174.
    PMID: 24574932 DOI: 10.1155/2014/917174
    The research on damages of structures that are supported by deep foundations has been quite intensive in the past decade. Kinematic interaction in soil-pile interaction is evaluated based on the p-y curve approach. Existing p-y curves have considered the effects of relative density on soil-pile interaction in sandy soil. The roughness influence of the surface wall pile on p-y curves has not been emphasized sufficiently. The presented study was performed to develop a series of p-y curves for single piles through comprehensive experimental investigations. Modification factors were studied, namely, the effects of relative density and roughness of the wall surface of pile. The model tests were subjected to lateral load in Johor Bahru sand. The new p-y curves were evaluated based on the experimental data and were compared to the existing p-y curves. The soil-pile reaction for various relative density (from 30% to 75%) was increased in the range of 40-95% for a smooth pile at a small displacement and 90% at a large displacement. For rough pile, the ratio of dense to loose relative density soil-pile reaction was from 2.0 to 3.0 at a small to large displacement. Direct comparison of the developed p-y curve shows significant differences in the magnitude and shapes with the existing load-transfer curves. Good comparison with the experimental and design studies demonstrates the multidisciplinary applications of the present method.
    Matched MeSH terms: Silicon Dioxide/chemistry
  4. Directed assembly of bifunctional silica-iron oxide nanocomposite with open shell structure
    Che HX, Yeap SP, Osman MS, Ahmad AL, Lim J
    ACS Appl Mater Interfaces, 2014 Oct 8;6(19):16508-18.
    PMID: 25198872 DOI: 10.1021/am5050949
    The synthesis of nanocomposite with controlled surface morphology plays a key role for pollutant removal from aqueous environments. The influence of the molecular size of the polyelectrolyte in synthesizing silica-iron oxide core-shell nanocomposite with open shell structure was investigated by using dynamic light scattering, atomic force microscopy, and quartz crystal microbalance with dissipation (QCM-D). Here, poly(diallydimethylammonium chloride) (PDDA) was used to promote the attachment of iron oxide nanoparticles (IONPs) onto the silica surface to assemble a nanocomposite with magnetic and catalytic bifunctionality. High molecular weight PDDA tended to adsorb on silica colloid, forming a more extended conformation layer than low molecular weight PDDA. Subsequent attachment of IONPs onto this extended PDDA layer was more randomly distributed, forming isolated islands with open space between them. By taking amoxicillin, an antibiotic commonly found in pharmaceutical waste, as the model system, better removal was observed for silica-iron oxide nanocomposite with a more extended open shell structure.
    Matched MeSH terms: Silicon Dioxide/chemistry*
  5. Dosimetric response of fabricated Ge-doped optical fibres in computed tomography RQT beam quality x-ray beams
    Rais NNM, Bradley DA, Hashim A, Isa NM, Osman ND, Ismail I, et al.
    J Radiol Prot, 2019 Sep;39(3):N8-N18.
    PMID: 31018196 DOI: 10.1088/1361-6498/ab1c16
    Novel germanium (Ge)-doped silica glass fibres tailor-made in Malaysia are fast gaining recognition as potential media for thermoluminescence (TL) dosimetry, with active research ongoing into exploitation of their various beneficial characteristics. Investigation is made herein of the capability of these media for use in diagnostic imaging dosimetry, specifically at the radiation dose levels typically obtained in conduct of Computed Tomography (CT). As a first step within such efforts, there is need to investigate the performance of the fibres using tightly defined spectra, use being made of a Philips constant potential industrial x-ray facility, Model MG165, located at the Malaysian Nuclear Agency Secondary Standards Dosimetry Lab (SSDL). Standard radiation beam qualities (termed RQT) have been established for CT, in accord with IEC 61267: 2003 and IAEA Technical Reports Series No. 457: 2007. A calibrated ionisation chamber has also been utilised, forming a component part of the SSDL equipment. The fabricated fibres used in this study are 2.3 mol% flat fibre (FF) of dimensions 643 × 356 μm2 and 2.3 mol% cylindrical fibre (CF) of 481 μm diameter, while the commercial fibre used is 4 mol% with core diameter of 50 μm. The dopant concentrations are nominal preform values. The fibres have been irradiated to doses of 20, 30 and 40 milligray (mGy) for each of the beam qualities RQT 8, RQT 9 and RQT 10. For x-rays generated at constant potential values from 100 to 150 kV, a discernible energy-dependent response is seen, comparisons being made with that of lithium fluoride (LiF) thermoluminescence dosimeters (TLD-100). TL yield versus dose has also been investigated for x-ray doses from 2 to 40 mGy, all exhibiting linearity. Compared to TLD-100, greater sensitivity is observed for the fibres.
    Matched MeSH terms: Silicon Dioxide/chemistry
  6. Effect of one-step polishing system on the color stability of nanocomposites
    Alawjali SS, Lui JL
    J Dent, 2013 Aug;41 Suppl 3:e53-61.
    PMID: 23103847 DOI: 10.1016/j.jdent.2012.10.008
    This study was to compare the effect of three different one-step polishing systems on the color stability of three different types of nanocomposites after immersion in coffee for one day and seven days and determine which nanocomposite material has the best color stability following polishing with each of the one-step polishing system.
    Matched MeSH terms: Silicon Dioxide/chemistry
  7. Fulltext Effect of sandblasting, silica coating, and erbium: Yttrium-Aluminum-Garnet laser treatment on the shear bond strength of self-adhesive resin cement to alumina ceramics
    Caglar I, Ates SM, Boztoprak Y, Aslan YU, Duymus ZY
    Niger J Clin Pract, 2018 Aug;21(8):1000-1007.
    PMID: 30074001 DOI: 10.4103/njcp.njcp_300_17
    Objective: The aim of this study was to investigate the different surface treatments on the bond strength of self-adhesive resin cement to high-strength ceramic.

    Materials and Methods: Ninety aluminum oxide ceramic (Turkom-Ceramic Sdn. Bhd., Kuala Lumpur, Malaysia) specimens were produced and divided into nine groups to receive the following surface treatments: control group, no treatment (Group C), sandblasting (Group B), silica coating (Group S), erbium: yttrium-aluminum-garnet (Er:YAG) laser irradiation at 150 mJ 10 Hz (Group L1), Er:YAG laser irradiation at 300 mJ 10 Hz (Group L2), sandblasting + L1 (Group BL1), sandblasting + L2 (Group BL2), silica coating + L1 (Group SL1), and silica coating + L2 (Group SL2). After surface treatments, surface roughness (SR) values were measured and surface topography was evaluated. Resin cement was applied on the specimen surface, and shear bond strength (SBS) tests were performed. Data were statistically analyzed using one-way ANOVA and Tukey's multiple comparisons at a significance level of P < 0.05.

    Results: Group S, SL1, and SL2 showed significantly increased SR values compared to the control group (P < 0.05); therefore, no significant differences were found among the SR values of Groups B, BL1, BL2, L1, and L2 and the control group (P > 0.05). Group S showed the highest SBS values, whereas the control group showed the lowest SBS values.

    Conclusion: Silica coating is the most effective method for resin bonding of high strength ceramic, but Er:YAG laser application decreased the effectiveness.

    Matched MeSH terms: Silicon Dioxide/chemistry*
  8. Effects of co-substrate and biomass acclimation concentration on the bioregeneration of azo dye-loaded mono-amine modified silica
    Al-Amrani WA, Lim PE, Seng CE, Wan Ngah WS
    Bioresour Technol, 2013 Sep;143:584-91.
    PMID: 23835263 DOI: 10.1016/j.biortech.2013.06.055
    Bioregeneration of mono-amine modified silica gel (MAMS) adsorbent loaded with Acid Orange 7 (AO7), Acid Yellow 9 (AY9) and Acid Red 14 (AR14), respectively, was investigated under two different operational conditions, namely absence/presence of sucrose/bacto-peptone as the co-substrate and different biomass acclimation concentrations. The results revealed that the AY9- and AR14-loaded MAMS adsorbents could almost be completely bioregenerated but only in the presence of co-substrate whereas the bioregeneration of AO7-loaded MAMS could achieve up to 71% in the absence of the co-substrate. These differences could be related to the structural properties of the investigated azo dyes. In addition, the results showed that the bioregeneration duration of AO7-loaded MAMS could be progressively shortened by using biomass acclimated to increasingly higher AO7 concentration. However, the bioregeneration efficiencies were found to be relatively unchanged under different biomass acclimation concentrations.
    Matched MeSH terms: Silicon Dioxide/chemistry*
  9. Fulltext Effects of using silica fume and polycarboxylate-type superplasticizer on physical properties of cementitious grout mixtures for semiflexible pavement surfacing
    Koting S, Karim MR, Mahmud H, Mashaan NS, Ibrahim MR, Katman H, et al.
    ScientificWorldJournal, 2014;2014:596364.
    PMID: 24526911 DOI: 10.1155/2014/596364
    Semi-flexible pavement surfacing is a composite pavement that utilizes the porous pavement structure of the flexible bituminous pavement, which is subsequently grouted with appropriate cementitious materials. This study aims to investigate the compressive strength, flexural strength, and workability performance of cementitious grout. The grout mixtures are designed to achieve high strength and maintain flow properties in order to allow the cement slurries to infiltrate easily through unfilled compacted skeletons. A paired-sample t-test was carried out to find out whether water/cement ratio, SP percentages, and use of silica fume influence the cementitious grout performance. The findings showed that the replacement of 5% silica fume with an adequate amount of superplasticizer and water/cement ratio was beneficial in improving the properties of the cementitious grout.
    Matched MeSH terms: Silicon Dioxide/chemistry*
  10. Elevated concentrations of naturally occurring radionuclides in heavy mineral-rich beach sands of Langkawi Island, Malaysia
    Khandaker MU, Asaduzzaman K, Sulaiman AFB, Bradley DA, Isinkaye MO
    Mar Pollut Bull, 2018 Feb;127:654-663.
    PMID: 29475708 DOI: 10.1016/j.marpolbul.2017.12.055
    Study is made of the radioactivity in the beach sands of Langkawi island, a well-known tourist destination. Investigation is made of the relative presence of the naturally occurring radionuclide 40K and the natural-series indicator radionuclides 226Ra and 232Th, the gamma radiation exposure also being estimated. Sample quantities of black and white sand were collected for gamma ray spectrometry, yielding activity concentration in black sands of 226Ra, 232Th and 40K from 451±9 to 2411±65Bqkg-1 (mean of 1478Bqkg-1); 232±4 to 1272±35Bqkg-1 (mean of 718Bqkg-1) and 61±6 to 136±7Bqkg-1 (mean of 103Bqkg-1) respectively. Conversely, in white sands the respective values for 226Ra and 232Th were appreciably lower, at 8.3±0.5 to 13.7±1.4Bqkg-1 (mean of 9.8Bqkg-1) and 4.5±0.7 to 9.4±1.0Bqkg-1 (mean of 5.9Bqkg-1); 40K activities differed insubstantially from that in black sands, at 85±4 to 133±7Bqkg-1 with a mean of 102Bqkg-1. The mean activity concentrations of 226Ra and 232Th in black sands are comparable with that of high background areas elsewhere in the world. The heavy minerals content gives rise to elevated 226Ra and 232Th activity concentrations in all of black sand samples. Evaluation of the various radiological risk parameters points to values which in some cases could be in excess of recommendations providing for safe living and working. Statistical analysis examines correlations between the origins of the radionuclides, also identifying and classifying the radiological parameters. Present results may help to form an interest in rare-earth resources for the electronics industry, power generation and the viability of nuclear fuels cycle resources.
    Matched MeSH terms: Silicon Dioxide/chemistry
  11. Encapsulation efficacy of natural and synthetic photosensitizers by silica nanoparticles for photodynamic applications
    Makhadmeh GN, Abdul Aziz A, Abdul Razak K, Abu Noqta O
    IET Nanobiotechnol, 2015 Dec;9(6):381-5.
    PMID: 26647815 DOI: 10.1049/iet-nbt.2015.0003
    This study analysed the physical effects of Cichorium Pumilum (CP), as a natural photosensitizer (PS), and Protoporphyrin IX (PpIX), as a synthetic PS, encapsulated with silica nanoparticles (SiNPs) in photodynamic therapy. The optimum concentrations of CP and PpIX, needed to destroy Red Blood Cells (RBC), were determined and the efficacy of encapsulated CP and PpIX were compared with naked CP and PpIX was verified. The results confirmed the applicability of CP and PpIX encapsulated in SiNPs on RBCs, and established a relationship between the encapsulated CP and PpIX concentration and the time required to rupture 50% of the RBCs (t50). The CP and PpIX encapsulated in SiNPs exhibited higher efficacy compared with that of naked CP and PpIX, respectively, and CP had less efficacy compared with PpIX.
    Matched MeSH terms: Silicon Dioxide/chemistry
  12. Ethyl-4-(aryl)-6-methyl-2-(oxo/thio)-3,4-dihydro-1H-pyrimidine-5-carboxylates: Silica supported bismuth(III)triflate catalyzed synthesis and antioxidant activity
    Gajjala RR, Chinta RR, Gopireddy VSR, Poola S, Balam SK, Chintha V, et al.
    Bioorg Chem, 2022 Dec;129:106205.
    PMID: 36265354 DOI: 10.1016/j.bioorg.2022.106205
    Novel ethyl-4-(aryl)-6-methyl-2-(oxo/thio)-3,4-dihydro-1H-pyrimidine-5-carboxylates were synthesized from one-pot, three-component Biginelli reaction of aryl aldehydes, ethyl acetoacetate and urea/ thiourea by catalytic action of silica supported Bismuth(III) triflate, a Lewis acid. All the synthesized compounds were structurally characterized by spectral (IR, 1H NMR & 13C NMR spectroscopic and Mass spectrometric) and elemental (C, H & N) analyses. The present protocol has deserved novel as, formed the products in high yields with short reaction times, involved eco-friendly methodology and reusable heterogeneous Lewis acid catalyst. The title compounds were screened for in vitro DPPH free radical scavenging antioxidant activity and identified 4i, 4j, 4h & 4f as potential antioxidants. The obtained in vitro results were correlated with molecular docking, ADMET, QSAR, Bioactivity & toxicity risk studies and molecular finger print properties and found that in silico binding affinities were identified in good correlation with in vitro antioxidant activity and studied the structure activity relationship. The molecular docking study has disclosed strong hydrogen bonding interactions of title compounds with aspartic acid (ASP197) aminoacid residue of 2HCK, a complex enzyme of haematopoietic cell kinase and quercetin. Results of toxicology study evaluated for potential risks of compounds have revealed title compounds as safer drugs. In ultimate the study has established ligand's antioxidant potentiality as they effectively binds with ASP197 amino acid of Chain A hence confirms the inhibition of growth of reactive oxygen species in vivo. In addition, the title compounds have been identified as potential blood-brain barrier penetrable entities and efficient central nervous system (CNS) active neuro-protective antioxidant agents.
    Matched MeSH terms: Silicon Dioxide/chemistry
  13. Evaluation of Ge-doped silica fibre TLDs for in vivo dosimetry during intraoperative radiotherapy
    Moradi F, Ung NM, Mahdiraji GA, Khandaker MU, See MH, Taib NA, et al.
    Phys Med Biol, 2019 04 12;64(8):08NT04.
    PMID: 30840946 DOI: 10.1088/1361-6560/ab0d4e
    Ge-doped silica fibre (GDSF) thermoluminescence dosimeters (TLD) are non-hygroscopic spatially high-resolution radiation sensors with demonstrated potential for radiotherapy dosimetry applications. The INTRABEAM® system with spherical applicators, one of a number of recent electronic brachytherapy sources designed for intraoperative radiotherapy (IORT), presents a representative challenging dosimetry situation, with a low keV photon beam and a desired rapid dose-rate fall-off close-up to the applicator surface. In this study, using the INTRABEAM® system, investigations were made into the potential application of GDSF TLDs for in vivo IORT dosimetry. The GDSFs were calibrated over the respective dose- and depth-range 1 to 20 Gy and 3 to 45 mm from the x-ray probe. The effect of different sizes of spherical applicator on TL response of the fibres was also investigated. The results show the GDSF TLDs to be applicable for IORT dose assessment, with the important incorporated correction for beam quality effects using different spherical applicator sizes. The total uncertainty in use of this type of GDSF for dosimetry has been found to range between 9.5% to 12.4%. Subsequent in vivo measurement of skin dose for three breast patients undergoing IORT were performed, the measured doses being below the tolerance level for acute radiation toxicity.
    Matched MeSH terms: Silicon Dioxide/chemistry
  14. Fulltext Experimental evaluation of oil recovery mechanism using a variety of surface-modified silica nanoparticles: Role of in-situ surface-modification in oil-wet system
    Adil M, Mohd Zaid H, Raza F, Agam MA
    PLoS One, 2020;15(7):e0236837.
    PMID: 32730369 DOI: 10.1371/journal.pone.0236837
    Recent developments propose renewed use of surface-modified nanoparticles (NPs) for enhanced oil recovery (EOR) due to improved stability and reduced porous media retention. The enhanced surface properties render the nanoparticles more suitable compared to bare nanoparticles, for increasing the displacement efficiency of waterflooding. However, the EOR mechanisms using NPs are still not well established. This work investigates the effect of in-situ surface-modified silica nanoparticles (SiO2 NPs) on interfacial tension (IFT) and wettability behavior as a prevailing oil recovery mechanism. For this purpose, the nanoparticles have been synthesized via a one-step sol-gel method using surface-modification agents, including Triton X-100 (non-ionic surfactant) and polyethylene glycol (polymer), and characterized using various techniques. These results exhibit the well-defined spherical particles, particularly in the presence of Triton X-100 (TX-100), with particle diameter between 13 to 27 nm. To this end, SiO2 nanofluids were formed by dispersing nanoparticles (0.05 wt.%, 0.075 wt.%, 0.1 wt.%, and 0.2 wt.%) in 3 wt.% NaCl to study the impact of surface functionalization on the stability of the nanoparticle suspension. The optimal stability conditions were obtained at 0.1 wt.% SiO2 NPs at a basic pH of 10 and 9.5 for TX-100/ SiO2 and PEG/SiO nanofluids, respectively. Finally, the surface-treated SiO2 nanoparticles were found to change the wettability of treated (oil-wet) surface into water-wet by altering the contact angle from 130° to 78° (in case of TX-100/SiO2) measured against glass surface representing carbonate reservoir rock. IFT results also reveal that the surfactant treatment greatly reduced the oil-water IFT by 30%, compared to other applied NPs. These experimental results suggest that the use of surface-modified SiO2 nanoparticles could facilitate the displacement efficiency by reducing IFT and altering the wettability of carbonate reservoir towards water-wet, which is attributed to more homogeneity and better dispersion of surface-treated silica NPs compared to bare-silica NPs.
    Matched MeSH terms: Silicon Dioxide/chemistry*
  15. Extraction of biogenic amines using sorbent materials containing immobilized crown ethers
    Saaid M, Saad B, Rahman IA, Ali AS, Saleh MI
    Talanta, 2010 Jan 15;80(3):1183-90.
    PMID: 20006072 DOI: 10.1016/j.talanta.2009.09.006
    Three sorbent materials (A18C6-MS, DA18C6-MS and AB18C6-MS) based on the crown ether ligands, 1-aza-18-crown-6, 1,4,10,13-tetraoxa-7,16-diazacyclo octadecane and 4'-aminobenzo-18-crown-6, respectively, were prepared by the chemical immobilization of the ligand onto mesoporous silica support. The sorbents were characterized by FT-IR, scanning electron microscopy-energy dispersive X-ray microanalysis, elemental analysis and nitrogen adsorption-desorption test. The applicability of the sorbents for the extraction of biogenic amines by the batch sorption method was extensively studied and evaluated as a function of pH, biogenic amines concentration, contact time and reusability. Under the optimized conditions, all the sorbents exhibited highest selectivity toward spermidine (SPD) compared to other biogenic amines (tryptamine, putrescine, histamine and tyramine). Among the sorbents, AB18C6-MS offer the highest capacity and best selectivity towards SPD in the presence of other biogenic amines. The AB18C6-MS sorbent can be repeatedly used three times as there was no significant degradation in the extraction of the biogenic amines (%E>85). The optimized procedure was successfully applied for the separation of SPD in food samples prior to the reversed-phase high performance liquid chromatography separation.
    Matched MeSH terms: Silicon Dioxide/chemistry
  16. Extraction of nanosilica from oil palm leaves and its application as support for lipase immobilization
    Onoja E, Chandren S, Razak FIA, Wahab RA
    J Biotechnol, 2018 Oct 10;283:81-96.
    PMID: 30063951 DOI: 10.1016/j.jbiotec.2018.07.036
    The study reports the preparation of a composite consisting of magnetite coated with nanosilica extracted from oil palm leaves (OPL) ash as nanosupports for immobilization of Candida rugosa lipase (CRL) and its application for the synthesis of butyl butyrate. Results of immobilization parameters showed that ∼ 80% of CRL (84.5 mg) initially offered was immobilized onto the surface of the nanosupports to yield a maximum protein loading and specific activity of 67.5 ± 0.72 mg/g and 320.8 ± 0.42 U/g of support, respectively. Surface topography, morphology as well as information on surface composition obtained by Raman spectroscopy, atomic force microscopy, field emission scanning electron microscopy and transmission electron microscopy showed that CRL was successfully immobilized onto the nanosupports, affirming its biocompatibility. Under optimal conditions (3.5 mg/mL protein loading, at 45 ℃, 3 h and molar ratio 2:1 (1-butanol:n-butyric acid) the CRL/Gl-A-SiO2-MNPs gave a maximum yield of 94 ± 0.24% butyl butyrate as compared to 84 ± 0.32% in the lyophilized CRL. CRL/Gl-A-SiO2-MNPs showed an extended operational stability, retaining 50% of its initial activity after 17 consecutive esterification cycles. The results indicated that OPL derived nanosilica coated on magnetite can potentially be employed as carrier for lipase immobilization in replacement of the non-renewable conventionalsilica sources.
    Matched MeSH terms: Silicon Dioxide/chemistry
  17. Extraction of phenanthrene and fluoranthene from contaminated sand using palm kernel and soybean oils
    Von Lau E, Gan S, Ng HK
    J Environ Manage, 2012 Sep 30;107:124-30.
    PMID: 22595079 DOI: 10.1016/j.jenvman.2012.04.029
    Experimental extraction tests are conducted to investigate feasibility of saturated palm kernel oil (PKO) and unsaturated soybean oil (SO) to extract polycyclic aromatic hydrocarbons (PAHs) from contaminated sand. The extraction rates and efficiencies for lowly contaminated (LC) and highly contaminated (HC) sands at temperatures of 30 °C and 70 °C are evaluated using empirical first order kinetic dissolution models. In LC sand, the extraction is dominated by the diffusion of PAHs adsorbed onto particle surfaces and the direct dissolution of PAH phase. In HC sand, a rapid diffusion of PAHs adsorbed onto particle surfaces and a direct dissolution of PAH phase occur followed by a slower diffusion of PAHs entrapped within the pores and micropores. Larger diffusion resistance during HC sand extractions results in an average 10.8% reduction in extraction efficiencies compared to LC sand. Increased temperature generally increases the mass transfer rates and extraction efficiencies. Additionally, the physicochemical properties of both oils and PAHs also determine the extent of PAH extraction into oil.
    Matched MeSH terms: Silicon Dioxide/chemistry*
  18. FTIR studies of PVC/PMMA blend based polymer electrolytes
    Ramesh S, Leen KH, Kumutha K, Arof AK
    Spectrochim Acta A Mol Biomol Spectrosc, 2007 Apr;66(4-5):1237-42.
    PMID: 16919998
    The polymer electrolytes composing of the blend of polyvinyl chloride-polymethyl methacrylate (PVC/PMMA) with lithium triflate (LiCF3SO3) as salt, ethylene carbonate (EC) and dibutyl phthalate (DBP) as plasticizers and silica (SiO2) as the composite filler were prepared. FTIR studies confirm the complexation between PVC/PMMA blends. The CCl stretching mode at 834 cm-1 for pure PVC is shifted to 847 cm-1 in PVC-PMMA-LiCF3SO3 system. This suggests that there is interaction between Cl in PVC with Li+ ion from LiCF3SO3. The band due to OCH3 at 1150 cm-1 for PVC-PMMA blend is shifted to 1168 cm-1 in PVC-PMMA-LiCF3SO3 system. This shift is expected to be due to the interaction between Li+ ion and the oxygen atom in PMMA. The symmetric vibration band and the asymmetric vibration band of LiCF3SO3 at 1033 and 1256 cm-1 shifted to 1075 and 1286 cm-1 in the DBP-EC plasticized PVC-PMMA-LiCF3SO3 complexes. The interaction between Li+ ions and SiO2 will lead to an increase in the number of free plasticizers (which does not interact with Li+ ions). When the silica content increases from 2% to 5%, the intensity of the peak at 896 cm-1 (due to the ring breathing vibration of free EC) increases in PVC-PMMA-LiCF3SO3-DBP-EC system.
    Matched MeSH terms: Silicon Dioxide/chemistry
  19. Functionalization of chitosan biopolymer with SiO2 nanoparticles and benzaldehyde via hydrothermal process for acid red 88 dye adsorption: Box-Behnken design optimization
    Wu R, Abdulhameed AS, Yong SK, Li H, ALOthman ZA, Wilson LD, et al.
    Int J Biol Macromol, 2023 Aug 30;247:125806.
    PMID: 37453635 DOI: 10.1016/j.ijbiomac.2023.125806
    An effective hydrothermally prepared chitosan-benzaldehyde/SiO2 adsorbent (CTA-BZA/SiO2) employed functionalization of a CTA biopolymer with SiO2 nanoparticles and BZA. CTA-BZA/SiO2 is an adsorbent that was utilized for the adsorption of an acidic dye (acid red 88, AR88) from synthetic wastewater. The fundamental adsorption variables (A: CTA-BZA/SiO2 dosage (0.02-0.1 g); B: pH (4-10); and C: duration (10-60)) were optimized via the Box-Behnken design (BBD). The Langmuir and Freundlich isotherms (coefficients of determination R2 = 0.99) agreed well with empirical data of AR88 adsorption by CTA-BZA/SiO2. The pseudo-first-order model showed reasonable agreement with the kinetic data of AR88 adsorption by CTA-BZA/SiO2. The maximal AR88 adsorption capacity (qmax) for CTA-BZA/SiO2 was identified to be 252.4 mg/g. The electrostatic attractions between both the positively charged CTA-BZA/SiO2 adsorbent and the AR88 anions, plus the n-π, π-π, and H-bond interactions contribute to the favourable adsorption process. This study reveals that CTA-BZA/SiO2 has the capacity to be a suitable adsorbent for the removal of a wider range of organic dyes from industrial effluents.
    Matched MeSH terms: Silicon Dioxide/chemistry
  20. Fulltext Green synthesis and characterization of UKMRC-8 rice husk-derived mesoporous silica nanoparticle for agricultural application
    Dorairaj D, Govender N, Zakaria S, Wickneswari R
    Sci Rep, 2022 Nov 23;12(1):20162.
    PMID: 36424408 DOI: 10.1038/s41598-022-24484-z
    Agriculture plays a crucial role in safeguarding food security, more so as the world population increases gradually. A productive agricultural system is supported by seed, soil, fertiliser and good management practices. Food productivity directly correlates to the generation of solid wastes and utilization of agrochemicals, both of which negatively impact the environment. The rice and paddy industry significantly adds to the growing menace of waste management. In low and middle-income countries, rice husk (RH) is an underutilized agro-waste discarded in landfills or burned in-situ. RH holds enormous potential in the development of value-added nanomaterials for agricultural applications. In this study, a simple and inexpensive sol-gel method is described to extract mesoporous silica nanoparticles (MSNs) from UKMRC8 RH using the bottom-up approach. RHs treated with hydrochloric acid were calcinated to obtain rice husk ash (RHA) with high silica purity (> 98% wt), as determined by the X-ray fluorescence analysis (XRF). Calcination at 650 °C for four hours in a box furnace yielded RHA that was devoid of metal impurities and organic matter. The X-ray diffraction pattern showed a broad peak at 2θ≈20-22 °C and was free from any other sharp peaks, indicating the amorphous property of the RHA. Scanning electron micrographs (SEM) showed clusters of spherically shaped uniform aggregates of silica nanoparticles (NPs) while transmission electron microscopy analysis indicated an average particle size of 
    Matched MeSH terms: Silicon Dioxide/chemistry
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