Displaying publications 281 - 300 of 448 in total

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  1. Photodynamic application of protoporphyrin IX as a photosensitizer encapsulated by silica nanoparticles
    Makhadmeh GN, Abdul Aziz A
    Artif Cells Nanomed Biotechnol, 2018;46(sup3):S1043-S1046.
    PMID: 30449196 DOI: 10.1080/21691401.2018.1528982
    BACKGROUND: Achieved Silica Nanoparticles (SiNPs) to encapsulate the photosensitizer [Protoporphyrin IX (PpIX)] in photodynamic therapy (PDT) application was reported in this research.

    MATERIALS AND METHODS: Cytotoxicity for five different concentrations of encapsulated and naked PpIX was measured. Optimum concentration and optimum exposure time of encapsulated and naked PpIX that needed to destroy the cells (Osteosarcoma cells) was measured.

    RESULTS: The results showed that the encapsulated PpIX has more efficacy compared to the naked PpIX and the applicability of the encapsulated PpIX-SiNPs was proved on osteosarcoma cells.

    CONCLUSION: The results established the important in-vitro photodynamic effectiveness of PpIX-SiNP, which may open a new application for PpIX in its clinical and in-vitro studies.

    Matched MeSH terms: Silicon Dioxide/therapeutic use*
  2. 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
  3. Recent advances in the application of silica nanostructures for highly improved water treatment: a review
    Salman M, Jahan S, Kanwal S, Mansoor F
    Environ Sci Pollut Res Int, 2019 Jul;26(21):21065-21084.
    PMID: 31124071 DOI: 10.1007/s11356-019-05428-z
    The demand for high-quality safe and clean water supply has revolutionized water treatment technologies and become a most focused subject of environmental science. Water contamination generally marks the presence of numerous toxic and harmful substances. These contaminants such as heavy metals, organic and inorganic pollutants, oil wastes, and chemical dyes are discharged from various industrial effluents and domestic wastes. Among several water treatment technologies, the utilization of silica nanostructures has received considerable attention due to their stability, sustainability, and cost-effective properties. As such, this review outlines the latest innovative approaches for synthesis and application of silica nanostructures in water treatment, apart from exploring the gaps that limit their large-scale industrial application. In addition, future challenges for improved water remediation and water quality technologies are keenly discussed.
    Matched MeSH terms: Silicon Dioxide/chemistry*
  4. 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
  5. Preparation, and structural of new NiS-SiO2 and Cr2S3-TiO2 nano-catalyst: Photocatalytic and antimicrobial studies
    Hosseini M, Fazelian N, Fakhri A, Kamyab H, Yadav KK, Chelliapan S
    J. Photochem. Photobiol. B, Biol., 2019 May;194:128-134.
    PMID: 30953914 DOI: 10.1016/j.jphotobiol.2019.03.016
    NiS-SiO2 and Cr2S3-TiO2 synthesized by Ultrasound-Microwave method was tested for the photo-degradation of methyl red as azo dye under ultraviolet (UV) light. The structure and morphology of the synthesized materials were examined through scanning electron microscopy, X-ray diffraction and photoelectron spectroscopy, energy-dispersive spectroscopy, dynamic light scattering and the band gap energy differences were determined through diffuse reflectance spectroscopy (DRS). The crystallite size and band gap values of SiO2, TiO2, NiS-SiO2 and Cr2S3-TiO2-1 were obtained from XRD and UV-vis DRS analysis and found insignificant 44.22, 54.11, and 57.11 nm, and 8.9, 3.2, 3.0, 2.7 eV, respectively. The NiS-SiO2 and Cr2S3-TiO2 nanocomposites exhibited good stability and catalytic performance in the azo dye degradation; the composite provides a complete degradation after 50 min under UV irradiation. The effects of different quencher compounds on the Methyl red dye degradation were also investigated. The result for this experiment shows the system without the quencher was highly degradation of Methyl red. The antibacterial influence of the SiO2, TiO2, NiS-SiO2 and Cr2S3-TiO2-1 were studied versus two species bacteria. The antifungal performance of this nanoparticle was analyzed versus two species fungi as the C. albicans and P. funiculosum. Biological data demonstrated that the prepared catalyst has great bactericidal and fungicidal properties.
    Matched MeSH terms: Silicon Dioxide/chemistry*
  6. Robust Magnetized Oil Palm Leaves Ash Nanosilica Composite as Lipase Support: Immobilization Protocol and Efficacy Study
    Onoja E, Wahab RA
    Appl Biochem Biotechnol, 2020 Oct;192(2):585-599.
    PMID: 32495234 DOI: 10.1007/s12010-020-03348-0
    Strategies to immobilize the individual enzymes are crucial for enhancing catalytic applicability and require a controlled immobilization process. Herein, protocol for immobilizing Candida rugosa lipase (CRL) onto modified magnetic silica derived from oil palm leaves ash (OPLA) was optimized for the effects of concentration of CRL, immobilization time, and temperature, monitored by titrimetric and spectrometric methods. XRD and TGA-DTG spectrometric observations indicated that OPLA-silica was well coated over magnetite (SiO2-MNPs) and CRLs were uniformly bound by covalent bonds to SiO2-MNPs (CRL/Gl-A-SiO2-MNPs). The optimized immobilization protocol showed that in the preparation of CRL/Gl-A-SiO2-MNPs, CRL with 68.3 mg/g protein loading and 74.6 U/g specific activity was achieved using 5 mg/mL of CRL, with an immobilization time of 12 h at 25 °C. The present work also demonstrated that acid-pretreated OPLA is a potential source of renewable silica, envisioning its applicability for practical use in enzymatic catalysis on solid support.
    Matched MeSH terms: Silicon Dioxide/chemistry*
  7. Silica nanoparticle assists determining liver cancer gene sequence on interdigitated electrode surface
    Song F, Yang Y, Gopinath SCB
    Biotechnol Appl Biochem, 2021 Jun;68(3):683-689.
    PMID: 32628799 DOI: 10.1002/bab.1980
    A high-performance interdigitated electrode (IDE) biosensing surface was reported here by utilizing self-assembled silica nanoparticle (SiNP). The modified surface was used to evaluate the complementation of hairpin forming region from Mitoxantrone resistance gene 7 (MXR7; liver cancer-related short gene). The conjugated SiNPs on 3-aminopropyl triethoxysilane functionalization were captured with probe sequence on IDE biosensing surface. The physical and chemically modified surface was used to quantify MXR7 and an increment in the current response upon complementation was noticed. Limit of target DNA detection was calculated (1-10 fM) and this label-free detection is at the comparable level to the fluorescent-based sensing. A linear regression was calculated [y = 0.243x - 0.0773; R² = 0.9336] and the sensitivity was 1 fM on the linear range of 1 fM to 10 pM. With the strong attachment of capture DNA on IDE through SiNP, the surface clearly discriminates the specificity (complementary) versus nonspecificity (complete-, single-, and triple-mismatched sequences). This detection strategy helps to determine liver cancer progression and the similar strategy can be followed for other gene sequence complementation.
    Matched MeSH terms: Silicon Dioxide/chemistry*
  8. Production and characterization of silica nanoparticles from fly ash: conversion of agro-waste into resource
    Uda MNA, Gopinath SCB, Hashim U, Halim NH, Parmin NA, Afnan Uda MN, et al.
    Prep Biochem Biotechnol, 2021;51(1):86-95.
    PMID: 32713293 DOI: 10.1080/10826068.2020.1793174
    A chemical method to synthesize amorphous silica nanoparticles from the incinerated paddy straw has been introduced. The synthesis was conducted through the hydrolysis by alkaline-acidic treatments. As a result, silica particles produced with the sizes were ranging at 60-90 nm, determined by high-resolution microscopy. The crystallinity was confirmed by surface area electron diffraction. Apart from that, chemical and diffraction analyses for both rice straw ash and synthesized silica nanoparticles were conducted by X-ray diffraction and Fourier-transform infrared spectroscopy. The percentage of silica from the incinerated straw was calculated to be 28.3. The prominent surface chemical bonding on the generated silica nanoparticles was with Si-O-Si, stretch of Si-O and symmetric Si-O bonds at peaks of 1090, 471, and 780 cm-1, respectively. To confirm the impurities of the elements in the produced silica, were analyzed using X-ray photoelectron spectroscopy and energy dispersive X-ray spectroscopy. The stability of silica nanoparticles was investigated using thermogravimetric analysis and zeta potential. The measured size from zeta potential analysis was 411.3-493 nm and the stability of mass reduction was located at 200 °C with final amount of mass reduced ∼88% and an average polydispersity Index was 0.195-0.224.
    Matched MeSH terms: Silicon Dioxide/chemistry*
  9. Nutrient fluxes across sediment-water interface in Bohai Bay Coastal Zone, China
    Mu D, Yuan D, Feng H, Xing F, Teo FY, Li S
    Mar Pollut Bull, 2017 Jan 30;114(2):705-714.
    PMID: 27802871 DOI: 10.1016/j.marpolbul.2016.10.056
    Sediment cores and overlying water samples were collected at four sites in Tianjin Coastal Zone, Bohai Bay, to investigate nutrient (N, P and Si) exchanges across the sediment-water interface. The exchange fluxes of each nutrient species were estimated based on the porewater profiles and laboratory incubation experiments. The results showed significant differences between the two methods, which implied that molecular diffusion alone was not the dominant process controlling nutrient exchanges at these sites. The impacts of redox conditions and bioturbation on the nutrient fluxes were confirmed by the laboratory incubation experiments. The results from this study showed that the nutrient fluxes measured directly from the incubation experiment were more reliable than that predicted from the porewater profiles. The possible impacts causing variations in the nutrient fluxes include sewage discharge and land reclamation.
    Matched MeSH terms: Silicon/analysis
  10. Fulltext Ultrasound-assisted sequentially precipitated nickel-silica catalysts and its application in the partial hydrogenation of edible oil
    Lim MSW, Yang TC, Tiong TJ, Pan GT, Chong S, Yap YH
    Ultrason Sonochem, 2021 May;73:105490.
    PMID: 33609992 DOI: 10.1016/j.ultsonch.2021.105490
    Sequentially precipitated Mg-promoted nickel-silica catalysts with ageing performed under various ultrasonic intensities were employed to study the catalyst performance in the partial hydrogenation of sunflower oil. Results from various characterisation studies showed that increasing ultrasonic intensity caused a higher degree of hydroxycarbonate erosion and suppressed the formation of Ni silicates and silica support, which improved Ni dispersion, BET surface area and catalyst reducibility. Growth of silica clusters on the catalyst aggregates were observed in the absence of ultrasonication, which explained the higher silica and nickel silicate content on the outer surface of the catalyst particle. Application of ultrasound also altered the electron density of the Ni species, which led to higher activity and enhanced product selectivity for sonicated catalysts. The catalyst synthesised with ultrasonic intensity of 20.78 Wcm-2 achieved 22.6% increase in hydrogenation activity, along with 28.5% decrease in trans-C18:1 yield at IV = 70, thus supporting the feasibility of such technique.
    Matched MeSH terms: Silicon Dioxide/chemistry*
  11. Metal-ion permeation in congested nanochannels: the exposure effect of Ag+ ions on the phosphorescent properties of a gold(I)-pyrazolate complex that is confined in the nanoscopic channels of mesoporous silica
    Lintang HO, Kinbara K, Yamashita T, Aida T
    Chem Asian J, 2012 Sep;7(9):2068-72.
    PMID: 22431445 DOI: 10.1002/asia.201200041
    An organometallic/silica nanocomposite of a 1D cylindrical assembly of a trinuclear gold(I)-pyrazolate complex ([Au(3)Pz(3)]) that was confined inside the nanoscopic channels of hexagonal mesoporous silica ([Au(3)Pz(3)]/silica(hex)), emitted red light with a luminescence center at 693 nm upon photoexcitation at 276 nm owing to a Au(I)-Au(I) metallophilic interaction. When a film of [Au(3)Pz(3)]/silica(hex) was dipped into a solution of Ag(+) in tetrahydrofuran (THF), the resulting nanocomposite material (Ag@[Au(3)Pz(3)]/silica(hex)) emitted green light with a new luminescence center at 486 nm, which was characteristic of a Au(I)-Ag(I) heterometallic interaction. Changes in the emission/excitation and XPS spectra of Ag@[Au(3)Pz(3)]/silica(hex) revealed that Ag(+) ions permeated into the congested nanochannels of [Au(3)Pz(3)]/silica(hex), which were filled with the cylindrical assembly of [Au(3)Pz(3)].
    Matched MeSH terms: Silicon Dioxide/chemistry*
  12. Bioregeneration of mono-amine modified silica and granular activated carbon loaded with Acid Orange 7 in batch system
    Al-Amrani WA, Lim PE, Seng CE, Ngah WS
    Bioresour Technol, 2012 Aug;118:633-7.
    PMID: 22704829 DOI: 10.1016/j.biortech.2012.05.090
    The objectives of this study were: (1) to investigate the role of mixed culture of biomass in the regeneration of mono-amine modified silica (MAMS) and granular activated carbon (GAC) loaded with Acid Orange 7 (AO7), (2) to quantify and compare the bioregeneration efficiencies of AO7-loaded MAMS and GAC using the sequential adsorption and biodegradation approach and (3) to evaluate the reusability of bioregenerated MAMS. The results show that considerably higher bioregeneration efficiency of AO7-loaded MAMS as compared to that of AO7-loaded GAC was achieved due to higher reversibility of adsorption of MAMS for AO7 and favorable pH factor resulting in more AO7 desorption. The progressive loss of adsorption capacity of MAMS for AO7 with multiple cycles of use suggests possible chemical and microbial fouling of the adsorption sites.
    Matched MeSH terms: Silicon Dioxide/chemistry*
  13. Fulltext Preparation, characterization and thermal degradation of polyimide (4-APS/BTDA)/SiO(2) composite films
    Ahmad MB, Gharayebi Y, Salit MS, Hussein MZ, Ebrahimiasl S, Dehzangi A
    Int J Mol Sci, 2012;13(4):4860-72.
    PMID: 22606014 DOI: 10.3390/ijms13044860
    Polyimide/SiO(2) composite films were prepared from tetraethoxysilane (TEOS) and poly(amic acid) (PAA) based on aromatic diamine (4-aminophenyl sulfone) (4-APS) and aromatic dianhydride (3,3,4,4-benzophenonetetracarboxylic dianhydride) (BTDA) via a sol-gel process in N-methyl-2-pyrrolidinone (NMP). The prepared polyimide/SiO(2) composite films were characterized using X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), scanning electron microscope (SEM) and thermogravimetric analysis (TGA). The FTIR results confirmed the synthesis of polyimide (4-APS/BTDA) and the formation of SiO(2) particles in the polyimide matrix. Meanwhile, the SEM images showed that the SiO(2) particles were well dispersed in the polyimide matrix. Thermal stability and kinetic parameters of the degradation processes for the prepared polyimide/SiO(2) composite films were investigated using TGA in N(2) atmosphere. The activation energy of the solid-state process was calculated using Flynn-Wall-Ozawa's method without the knowledge of the reaction mechanism. The results indicated that thermal stability and the values of the calculated activation energies increased with the increase of the TEOS loading and the activation energy also varied with the percentage of weight loss for all compositions.
    Matched MeSH terms: Silicon Dioxide/chemistry*
  14. 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
  15. Catalyst free silica templated porous carbon nanoparticles from bio-waste materials
    Kumar A, Hegde G, Manaf SA, Ngaini Z, Sharma KV
    Chem Commun (Camb), 2014 Oct 28;50(84):12702-5.
    PMID: 25100105 DOI: 10.1039/c4cc04378b
    Porous Carbon Nanoparticles (PCNs) with well-developed microporosity were obtained from bio-waste oil palm leaves (OPL) using single step pyrolysis in nitrogen atmosphere at 500-600 °C in tube-furnace without any catalysis support. The key approach was using silica (SiO2) bodies of OPL as a template in the synthesis of microporous carbon nanoparticles with very small particle sizes of 35-85 nm and pore sizes between 1.9-2 nm.
    Matched MeSH terms: Silicon Dioxide/chemistry*
  16. Fulltext Modeling and analysis of a microresonating biosensor for detection of Salmonella bacteria in human blood
    Bahadoran M, Noorden AF, Chaudhary K, Mohajer FS, Aziz MS, Hashim S, et al.
    Sensors (Basel), 2014;14(7):12885-99.
    PMID: 25046015 DOI: 10.3390/s140712885
    A new photonics biosensor configuration comprising a Double-side Ring Add-drop Filter microring resonator (DR-ADF) made from SiO2-TiO2 material is proposed for the detection of Salmonella bacteria (SB) in blood. The scattering matrix method using inductive calculation is used to determine the output signal's intensities in the blood with and without presence of Salmonella. The change in refractive index due to the reaction of Salmonella bacteria with its applied antibody on the flagellin layer loaded on the sensing and detecting microresonator causes the increase in through and dropper port's intensities of the output signal which leads to the detection of SB in blood. A shift in the output signal wavelength is observed with resolution of 0.01 nm. The change in intensity and shift in wavelength is analyzed with respect to the change in the refractive index which contributes toward achieving an ultra-high sensitivity of 95,500 nm/RIU which is almost two orders higher than that of reported from single ring sensors and the limit of detection is in the order of 1 × 10(-8) RIU. In applications, such a system can be employed for a high sensitive and fast detection of bacteria.
    Matched MeSH terms: Silicon Dioxide/chemistry
  17. Novel utilization of waste marine sponge (Demospongiae) as a catalyst in ultrasound-assisted transesterification of waste cooking oil
    Hindryawati N, Maniam GP
    Ultrason Sonochem, 2015 Jan;22:454-62.
    PMID: 24842471 DOI: 10.1016/j.ultsonch.2014.04.011
    This study demonstrates the potential of Na-silica waste sponge as a source of low cost catalyst in the transesterification of waste cooking oil aided by ultrasound. In this work an environmentally friendly and efficient transesterification process using Na-loaded SiO2 from waste sponge skeletons as a solid catalyst is presented. The results showed that the methyl esters content of 98.4±0.4wt.% was obtainable in less than an hour (h) of reaction time at 55°C. Optimization of reaction parameters revealed that MeOH:oil, 9:1; catalyst, 3wt.% and reaction duration of 30min as optimum reaction conditions. The catalyst is able to tolerant free fatty acid and moisture content up to 6% and 8%, respectively. In addition, the catalyst can be reused for seven cycles while maintaining the methyl esters content at 86.3%. Ultrasound undoubtedly assisted in achieving this remarkable result in less than 1h reaction time. For the kinetics study at 50-60°C, a pseudo first order model was proposed, and the activation energy of the reaction is determined as 33.45kJ/mol using Arrhenius equation.
    Matched MeSH terms: Silicon Dioxide/chemistry
  18. Variation of the crystal growth of mesoporous silica nanoparticles and the evaluation to ibuprofen loading and release
    Kamarudin NH, Jalil AA, Triwahyono S, Artika V, Salleh NF, Karim AH, et al.
    J Colloid Interface Sci, 2014 May 1;421:6-13.
    PMID: 24594025 DOI: 10.1016/j.jcis.2014.01.034
    Mesoporous silica nanoparticles (MSNs) were synthesized with variable microwave power in the range of 100-450 W, and the resulting enhancement of MSN crystal growth was evaluated for the adsorption and release of ibuprofen. X-ray diffraction (XRD) revealed that the MSN prepared under the highest microwave power (MSN450) produced the most crystallized and prominent mesoporous structure. Enhancement of the crystal growth improved the hexagonal order and range of silica, which led to greater surface area, pore width and pore volume. MSN450 exhibited higher ibuprofen adsorption (98.3 mg/g), followed by MSN300(81.3 mg/g) and MSN100(74.1 mg/g), confirming that more crystallized MSN demonstrated higher adsorptivity toward ibuprofen. Significantly, MSN450 also contained more hydroxyl groups that provided more adsorption sites. In addition, MSN450 exhibited comparable ibuprofen adsorption with conventionally synthesized MSN, indicating the potential of microwave treatment in the synthesis of related porous materials. In vitro drug release was also investigated with simulated biological fluids and the kinetics was studied under different pH conditions. MSN450 showed the slowest release rate of ibuprofen, followed by MSN300 and MSN100. This was due to the wide pore diameter and longer range of silica order of the MSN450. Ibuprofen release from MSN450 at pH 5 and 7 was found to obey a zero-order kinetic model, while release at pH 2 followed the Kosmeyer-Peppas model.
    Matched MeSH terms: Silicon Dioxide/chemistry*
  19. In vitro and in vivo evaluation of hydrophilic and hydrophobic polymers-based nicorandil-loaded peroral tablet compared with its once-daily commercial sustained-release tablet
    Tamilvanan S, Venkatesh Babu R, Nappinai A, Sivaramakrishnan G
    Drug Dev Ind Pharm, 2011 Apr;37(4):436-45.
    PMID: 20923389 DOI: 10.3109/03639045.2010.521161
    Hydrophilic and hydrophobic polymer-based nicorandil (10 mg)-loaded peroral tablets were prepared using the wet granulation technique. The influence of varying amounts of hydroxypropyl methylcellulose (HPMC) (30-50 mg), ethylcellulose (2-4 mg), microcrystalline cellulose (5-20 mg) and Aerosil® (5-12 mg) in conjunction with the constant amounts (3 mg) of glidant and lubricant (magnesium stearate and talc) on the in vitro performances of the tablets (hardness, friability, weight variation, thickness uniformity, drug content, and drug release behavior) were investigated.
    Matched MeSH terms: Silicon Dioxide/administration & dosage
  20. Iron incorporated heterogeneous catalyst from rice husk ash
    Adam F, Kandasamy K, Balakrishnan S
    J Colloid Interface Sci, 2006 Dec 1;304(1):137-43.
    PMID: 16996077
    Silica supported iron catalyst was prepared from rice husk ash (RHA) via the sol-gel technique using an aqueous solution of iron(III) salt in 3.0 M HNO3. The sample was dried at 110 degrees C and labeled as RHA-Fe. A sample of RHA-Fe was calcined at 700 degrees C for 5 h and labeled as RHA-Fe700. X-ray diffraction spectrogram showed that both RHA-Fe and RHA-Fe700 were amorphous. The SEM/EDX results showed that the metal was present as agglomerates and the Fe ions were not homogeneously distributed in RHA-Fe but RHA-Fe700 was shown to be homogeneous. The specific surface areas for RHA-Fe and RHA-Fe700 were determined by BET nitrogen adsorption studies and found to be 87.4 and 55.8 m(2) g(-1), respectively. Both catalysts showed high activity in the reaction between toluene and benzyl chloride. The mono-substituted benzyltoluene was the major product and both catalysts yielded more than 92% of the product. The GC showed that both the ortho- and para-substituted monoisomers were present in about equal quantities. The minor products consisting of 16 di-substituted isomers were also observed in the GC-MS spectra of both catalytic products. The catalyst was found to be reusable without loss of activity and with no leaching of the metal.
    Matched MeSH terms: Silicon Dioxide/chemistry*
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