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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*
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*
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*
Bioactive scaffold (sodium alginate)-g-(nHAp@SiO2@GO) for bone tissue engineering

Khan MUA, Razak SIA, Rehman S, Hasan A, Qureshi S, Stojanović GM

Int J Biol Macromol, 2022 Dec 01;222(Pt A):462-472.
PMID: 36155784 DOI: 10.1016/j.ijbiomac.2022.09.153

Globally, people suffering from bone disorders are steadily increasing and bone tissue engineering is an advanced approach to treating fractured and defected bone tissues. In this study, we have prepared polymeric nanocomposite by free-radical polymerization from sodium alginate, hydroxyapatite, and silica with different GO amounts. The porous scaffolds were fabricated using the freeze drying technique. The structural, morphological, mechanical, and wetting investigation was conducted by Fourier-transform infrared spectroscopy, X-ray diffraction, scanning electron microscope, universal tensile machine, and water contact angle characterization techniques. The swelling, biodegradation, and water retention were also studied. The biological studies were performed (cell viability, cell adherence, proliferation, and mineralization) against osteoblast cell lines. Scaffolds have exhibited different pore morphology SAG-1 (pore size = 414.61 ± 56 μm and porosity = 81.45 ± 2.17 %) and SAG-4 (pore size = 195.97 ± 82 μm and porosity = 53.82 ± 2.45 %). They have different mechanical behavior as SAG-1 has the least compression strength and compression modulus 2.14 ± 2.35 and 16.51 ± 1.27 MPa. However, SAG-4 has maximum compression strength and compression modulus 13.67 ± 2.63 and 96.16 ± 1.97 MPa with wetting behavior 80.70° and 58.70°, respectively. Similarly, SAG-1 exhibited the least and SAG-4 presented maximum apatite mineral formation, cell adherence, cell viability, and cell proliferation against mouse pre-osteoblast cell lines. The increased GO amount provides different multifunctional materials with different characteristics. Hence, the fabricated scaffolds could be potential scaffold materials to treat and regenerate fracture bone tissues in bone tissue engineering.

Matched MeSH terms: Silicon Dioxide*
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
Tailor-made Ge-doped silica-glass for clinical diagnostic X-ray dosimetry

Alyahyawi A, Jupp T, Alkhorayef M, Bradley DA

Appl Radiat Isot, 2018 Aug;138:45-49.
PMID: 28780202 DOI: 10.1016/j.apradiso.2017.07.011

In the modern clinical practice of diagnostic radiology there is a growing demand for radiation dosimetry, it also being recognized that with increasing use of X-ray examinations additional population dose will result, accompanied by an additional albeit low potential for genetic consequences. At the doses typical of diagnostic radiology there is also a low statistical risk for cancer induction; in adhering to best practice, to be also implied is a low but non-negligible potential for deterministic sensitive organ responses, including in regard to the skin and eyes. Risk reduction is important, in line with the principle of ALARP, both in regard to staff and patients alike; for the latter modern practice is usually guided by Dose Reference Levels (DRL) while for the former and members of the public, legislated controls (supported by safe working practices) pertain. As such, effective, reliable and accurate means of dosimetry are required in support of these actions. Recent studies have shown that Ge-doped-silica glass fibres offer several advantages over the well-established phosphor-based TL dosimeters (TLD), including excellent sensitivity at diagnostic doses as demonstrated herein, low fading, good reproducibility and re-usability, as well as representing a water impervious, robust dosimetric system. In addition, these silica-based fibres show good linearity over a wide dynamic range of dose and dose-rate and are directionally independent. In the present study, we investigate tailor made doped-silica glass thermoluminescence (TL) for applications in medical diagnostic imaging dosimetry. The aim is to develop a dosimeter of sensitivity greater than that of the commonly used LiF (Mg,Ti) phosphor. We examine the ability of such doped glass media to detect the typically low levels of radiation in diagnostic applications (from fractions of a mGy through to several mGy or more), including, mammography and dental radiology, use being made of x-ray tubes located at the Royal Surrey County Hospital. We further examine dose-linearity, energy response and fading.

Matched MeSH terms: Silicon Dioxide*
Magnetic micro-solid-phase extraction based on magnetite-MCM-41 with gas chromatography-mass spectrometry for the determination of antidepressant drugs in biological fluids

Kamaruzaman S, Sanagi MM, Yahaya N, Wan Ibrahim WA, Endud S, Wan Ibrahim WN

J Sep Sci, 2017 Nov;40(21):4222-4233.
PMID: 28837263 DOI: 10.1002/jssc.201700549

A new facile magnetic micro-solid-phase extraction coupled to gas chromatography and mass spectrometry detection was developed for the extraction and determination of selected antidepressant drugs in biological fluids using magnetite-MCM-41 as adsorbent. The synthesized sorbent was characterized by several spectroscopic techniques. The maximum extraction efficiency for extraction of 500 μg/L antidepressant drugs from aqueous solution was obtained with 15 mg of magnetite-MCM-41 at pH 12. The analyte was desorbed using 100 μL of acetonitrile prior to gas chromatography determination. This method was rapid in which the adsorption procedure was completed in 60 s. Under the optimized conditions using 15 mL of antidepressant drugs sample, the calibration curve showed good linearity in the range of 0.05-500 μg/L (r2 = 0.996-0.999). Good limits of detection (0.008-0.010 μg/L) were obtained for the analytes with good relative standard deviations of <8.0% (n = 5) for the determination of 0.1, 5.0, and 500.0 μg/L of antidepressant drugs. This method was successfully applied to the determination of amitriptyline and chlorpromazine in plasma and urine samples. The recoveries of spiked plasma and urine samples were in the range of 86.1-115.4%. Results indicate that magnetite micro-solid-phase extraction with gas chromatography and mass spectrometry is a convenient, fast, and economical method for the extraction and determination of amitriptyline and chlorpromazine in biological samples.

Matched MeSH terms: Silicon Dioxide*
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
Fulltext Dominant phytoplankton groups as the major source of polyunsaturated fatty acids for hilsa (Tenualosa ilisha) in the Meghna estuary Bangladesh

Shaha DC, Hasan J, Kundu SR, Yusoff FM, Salam MA, Khan M, et al.

Sci Rep, 2022 Dec 05;12(1):20980.
PMID: 36470973 DOI: 10.1038/s41598-022-24500-2

The tropical estuarine ecosystem is fascinating for studying the dynamics of water quality and phytoplankton diversity due to its frequently changing hydrological conditions. Most importantly, phytoplankton is the main supplier of ω3 polyunsaturated fatty acids (PUFA) in the coastal food web for fish as they could not synthesize PUFA. This study evaluated seasonal variations of water quality parameters in the Meghna River estuary (MRE), explored how phytoplankton diversity changes according to hydro-chemical parameters, and identified the major phytoplankton groups as the main source of PUFA for hilsa fish. Ten water quality indicators including temperature, dissolved oxygen, pH, salinity, dissolved inorganic nitrogen (DIN = nitrate, nitrite, ammonia) and phosphorus, dissolved silica and chlorophyll-a were evaluated. In addition, phytoplankton diversity was assessed in the water and hilsa fish gut. Principal component analysis (PCA) was used to analyze the spatio-temporal changes in the water quality conditions, and the driving factors in the MRE. Four main components were extracted and explained 75.4% variability of water quality parameters. The most relevant driving factors were dissolved oxygen, salinity, temperature, and DIN (nitrate, nitrite and ammonia). These variabilities in physicochemical parameters and dissolved inorganic nutrients caused seasonal variations in two major groups of phytoplankton. Peak abundance of Chlorophyta (green algae) occurred in water in nutrient-rich environments (nitrogen and phosphorus) during the wet (36%) season, while Bacillariophyta (diatoms) were dominant during the dry (32%) season that depleted dissolved silica. Thus, the decrease of green algae and the increase of diatoms in the dry season indicated the potential link to seasonal changes of hydro-chemical parameters. The green algae (53.7%) were the dominant phytoplankton group in the hilsa gut content followed by diatoms (22.6%) and both are contributing as the major source of PUFAs for hilsa fish according to the electivity index as they contain the highest amounts of PUFAs (60 and 28% respectively).

Matched MeSH terms: Silicon Dioxide/analysis
Kinetic study on removal of heavy metal ions from aqueous solution by using soil

Lim SF, Lee AY

Environ Sci Pollut Res Int, 2015 Jul;22(13):10144-58.
PMID: 25854202 DOI: 10.1007/s11356-015-4203-6

In the present study, the feasibility of soil used as a low-cost adsorbent for the removal of Cu(2+), Zn(2+), and Pb(2+) ions from aqueous solution was investigated. The kinetics for adsorption of the heavy metal ions from aqueous solution by soil was examined under batch mode. The influence of the contact time and initial concentration for the adsorption process at pH of 4.5, under a constant room temperature of 25 ± 1 °C were studied. The adsorption capacity of the three heavy metal ions from aqueous solution was decreased in order of Pb(2+) > Cu(2+) > Zn(2+). The soil was characterized by Fourier transform infrared (FTIR) spectroscopy, scanning electron microscopic-energy dispersive X-ray (SEM-EDX), and Brunauer, Emmett, and Teller (BET) surface area analyzer. From the FTIR analysis, the experimental data was corresponded to the peak changes of the spectra obtained before and after adsorption process. Studies on SEM-EDX showed distinct adsorption of the heavy metal ions and the mineral composition in the study areas were determined to be silica (SiO2), alumina (Al2O3), and iron(III) oxide (FeO3). A distinct decrease of the specific surface area and total pore volumes of the soil after adsorption was found from the BET analysis. The experimental results obtained were analyzed using four adsorption kinetic models, namely pseudo-first-order, pseudo-second-order, Elovich, and intraparticle diffusion. Evaluating the linear correlation coefficients, the kinetic studies showed that pseudo-second-order equation described the data appropriable than others. It was concluded that soil can be used as an effective adsorbent for removing Cu(2+), Zn(2+), and Pb(2+) ions from aqueous solution.

Matched MeSH terms: Silicon Dioxide/chemistry
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*
Cytotoxic evaluation of hydroxyapatite-filled and silica/hydroxyapatite-filled acrylate-based restorative composite resins: An in vitro study

Chadda H, Naveen SV, Mohan S, Satapathy BK, Ray AR, Kamarul T

J Prosthet Dent, 2016 Jul;116(1):129-35.
PMID: 26873771 DOI: 10.1016/j.prosdent.2015.12.013

STATEMENT OF PROBLEM: Although the physical and mechanical properties of hydroxyapatite-filled dental restorative composite resins have been examined, the biocompatibility of these materials has not been studied in detail.
PURPOSE: The purpose of this in vitro study was to analyze the toxicity of acrylate-based restorative composite resins filled with hydroxyapatite and a silica/hydroxyapatite combination.
MATERIAL AND METHODS: Five different restorative materials based on bisphenol A-glycidyl methacrylate (bis-GMA) and tri-ethylene glycol dimethacrylate (TEGDMA) were developed: unfilled (H0), hydroxyapatite-filled (H30, H50), and silica/hydroxyapatite-filled (SH30, SH50) composite resins. These were tested for in vitro cytotoxicity by using human bone marrow mesenchymal stromal cells. Surface morphology, elemental composition, and functional groups were determined by scanning electron microscopy (SEM), energy-dispersive x-ray spectroscopy (EDX), and Fourier-transformed infrared spectroscopy (FTIR). The spectra normalization, baseline corrections, and peak integration were carried out by OPUS v4.0 software.
RESULTS: Both in vitro cytotoxicity results and SEM analysis indicated that the composite resins developed were nontoxic and supported cell adherence. Elemental analysis with EDX revealed the presence of carbon, oxygen, calcium, silicon, and gold, while the presence of methacrylate, hydroxyl, and methylene functional groups was confirmed through FTIR analysis.
CONCLUSIONS: The characterization and compatibility studies showed that these hydroxyapatite-filled and silica/hydroxyapatite-filled bis-GMA/TEGDMA-based restorative composite resins are nontoxic to human bone marrow mesenchymal stromal cells and show a favorable biologic response, making them potential biomaterials.

Matched MeSH terms: Silicon Dioxide/adverse effects; Silicon Dioxide/therapeutic use
New chrysin-functionalized silica-core shell magnetic nanoparticles for the magnetic solid phase extraction of copper ions from water samples

Abd Ali LI, Ibrahim WA, Sulaiman A, Kamboh MA, Sanagi MM

Talanta, 2016 Feb 1;148:191-9.
PMID: 26653440 DOI: 10.1016/j.talanta.2015.10.062

This study describes the synthesis, characterization and application of a new chrysin-based silica core-shell magnetic nanoparticles (Fe3O4@SiO2-N-chrysin) as an adsorbent for the preconcentration of Cu(II) from aqueous environment. The morphology, thermal stability and magnetic property of Fe3O4@SiO2-N-chrysin were analyzed using FTIR, FESEM, TEM, XRD, thermal analysis and VSM. The extraction efficiency of Fe3O4@SiO2-N-chrysin was analyzed using the batch wise method with flame atomic absorption spectrometry. Parameters such as the pH, the sample volume, the adsorption-desorption time, the concentration of the desorption solvent, the desorption volume, the interference effects and the regeneration of the adsorbent were optimized. It was determined that Cu(II) adsorption is highly pH-dependent, and a high recovery (98%) was achieved at a pH 6. The limit of detection (S/N=3), the limit of quantification (S/N=10), the preconcentration factor and the relative standard deviation for Cu(II) extraction were 0.3 ng mL(-1), 1 ng mL(-1), 100 and 1.9% (concentration=30 ng mL(-1), n=7), respectively. Excellent relative recoveries of 97-104% (%RSD<3.12) were achieved from samples from a spiked river, a lake and tap water. The MSPE method was also validated using certified reference materials SLRS-5 with good recovery (92.53%).

Matched MeSH terms: Silicon Dioxide
The effects of season and sand mining activities on thermal regime and water quality in a large shallow tropical lake

Sharip Z, Zaki AT

Environ Monit Assess, 2014 Aug;186(8):4959-69.
PMID: 24696283 DOI: 10.1007/s10661-014-3751-4

Thermal structure and water quality in a large and shallow lake in Malaysia were studied between January 2012 and June 2013 in order to understand variations in relation to water level fluctuations and in-stream mining activities. Environmental variables, namely temperature, turbidity, dissolved oxygen, pH, electrical conductivity, chlorophyll-A and transparency, were measured using a multi-parameter probe and a Secchi disk. Measurements of environmental variables were performed at 0.1 m intervals from the surface to the bottom of the lake during the dry and wet seasons. High water level and strong solar radiation increased temperature stratification. River discharges during the wet season, and unsustainable sand mining activities led to an increased turbidity exceeding 100 NTU, and reduced transparency, which changed the temperature variation and subsequently altered the water quality pattern.

Matched MeSH terms: Silicon Dioxide
Fulltext Investigating the effect of lignosulfonate on erosion rate of the embankments constructed with clayey sand

Koohpeyma HR, Vakili AH, Moayedi H, Panjsetooni A, Nazir R

ScientificWorldJournal, 2013;2013:587462.
PMID: 24459437 DOI: 10.1155/2013/587462

Internal erosion is known as the most important cause of dam failure after overtopping. It is important to improve the erosion resistance of the erodible soil by selecting an effective technique along with the reasonable costs. To prevent internal erosion of embankment dams the use of chemical stabilizers that reduce the soil erodibility potential is highly recommended. In the present study, a lignin-based chemical, known as lignosulfonate, is used to improve the erodibility of clayey sand specimen. The clayey sand was tested in various hydraulic heads in terms of internal erosion in its natural state as well as when it is mixed with the different percentages of lignosulfonate. The results show that erodibility of collected clayey sand is very high and is dramatically reduced by adding lignosulfonate. Adding 3% of lignosulfonate to clayey sand can reduce the coefficient of soil erosion from 0.01020 to 0.000017. It is also found that the qualitative erodibility of stabilized soil with 3% lignosulfonate is altered from the group of extremely rapid to the group of moderately slow.

Matched MeSH terms: Silicon Dioxide
On the sensitivity of some common metallographic reagents to restoring obliterated marks on medium carbon (0.31% C) steel surfaces

Yin SH, Kuppuswamy R

Forensic Sci Int, 2009 Jan 10;183(1-3):50-3.
PMID: 19041202 DOI: 10.1016/j.forsciint.2008.10.009

Chemical etching, which is the most sensitive method to recover obliterated serial numbers on metal surfaces, has been practised quite successfully in forensic science laboratories all over the world. A large number of etchants suitable for particular metal surfaces based on empirical studies is available in the literature. This article reviews the sensitivity and efficacy of some popular etchants for recovering obliterated marks on medium carbon steel (0.31% C with ferrite-pearlite microstructure) used in automobile parts. The experiments involved engraving these carbon steel plates with some alphanumeric characters using a computer controlled machine "Gravograph" and erasing them to several depths below the bottom of their engraving depth. Seven metallographic reagents of which most of them were copper containing compounds were chosen for etching. The erased plates were etched with every one of these etchants using swabbing method. The results have revealed that Fry's reagent comprising cupric chloride 90 g, hydrochloric acid 120 mL and water 100mL provided the necessary contrast and was concluded to be the most sensitive. The same reagent was recommended by earlier workers for revealing strain lines in steel surfaces. Earlier, another reagent containing 5 g copper sulphate, 60 mL water, 30 mL (conc.) ammonium hydroxide, and 60 mL (conc.) hydrochloric acid was proved to be more sensitive to restore erased marks on low carbon steel (0.1% C with ferrite-pearlite structure) [M.A.M. Zaili, R. Kuppuswamy, H. Harun, Restoration of engraved marks on steel surfaces by etching technique, Forensic Sci. Int. 171 (2007) 27-32]. Thus the sensitivity of the etching reagent on steel surfaces appeared to be dependent on the content of carbon in the steel.

Matched MeSH terms: Silicon Dioxide
Online preconcentration of arsenic compounds by dynamic pH junction-capillary electrophoresis

Jaafar J, Irwan Z, Ahamad R, Terabe S, Ikegami T, Tanaka N

J Sep Sci, 2007 Feb;30(3):391-8.
PMID: 17396598

An online preconcentration technique by dynamic pH junction was studied to improve the detection limit for anionic arsenic compounds by CE. The main target compound is roxarsone, or 3-nitro-4-hydroxyphenylarsonic acid, which is being used as an animal feed additive. The other inorganic and organoarsenic compounds studied are the possible biotransformation products of roxarsone. The arsenic species were separated by a dynamic pH junction in a fused-silica capillary using 15 mM phosphate buffer (pH 10.6) as the BGE and 15 mM acetic acid as the sample matrix. CE with UV detection was monitored at a wavelength of 192 nm. The influence of buffer pH and concentration on dynamic pH junction were investigated. The arsenic species focusing resulted in LOD improvement by a factor of 100-800. The combined use of C18 and anion exchange SPE and dynamic pH junction to CE analysis of chicken litter and soils helps to increase the detection sensitivity. Recoveries of spiked samples ranged between 70 and 72%.

Matched MeSH terms: Silicon Dioxide
Fulltext Bioactivity studies and adhesion of human osteoblast (hFOB) on silicon-biphasic calcium phosphate material

Ibrahim S, Sabudin S, Sahid S, Marzuke MA, Hussin ZH, Kader Bashah NS, et al.

Saudi J Biol Sci, 2016 Jan;23(1):S56-63.
PMID: 26858566 DOI: 10.1016/j.sjbs.2015.10.024

Surface reactivity of bioactive ceramics contributes in accelerating bone healing by anchoring osteoblast cells and the connection of the surrounding bone tissues. The presence of silicon (Si) in many biocompatible and bioactive materials has been shown to improve osteoblast cell adhesion, proliferation and bone regeneration due to its role in the mineralisation process around implants. In this study, the effects of Si-biphasic calcium phosphate (Si-BCP) on bioactivity and adhesion of human osteoblast (hFOB) as an in vitro model have been investigated. Si-BCP was synthesised using calcium hydroxide (Ca(OH)2) and phosphoric acid (H3PO4) via wet synthesis technique at Ca/P ratio 1.60 of material precursors. SiO2 at 3 wt% based on total precursors was added into apatite slurry before proceeding with the spray drying process. Apatite powder derived from the spray drying process was pressed into discs with Ø 10 mm. Finally, the discs were sintered at atmospheric condition to obtain biphasic hydroxyapatite (HA) and tricalcium phosphate (TCP) peaks simultaneously and examined by XRD, AFM and SEM for its bioactivity evaluation. In vitro cell viability of L929 fibroblast and adhesion of hFOB cell were investigated via AlamarBlue® (AB) assay and SEM respectively. All results were compared with BCP without Si substitution. Results showed that the presence of Si affected the material's surface and morphology, cell proliferation and cell adhesion. AFM and SEM of Si-BCP revealed a rougher surface compared to BCP. Bioactivity in simulated body fluid (SBF) was characterised by pH, weight gain and apatite mineralisation on the sample surface whereby the changes in surface morphology were evaluated using SEM. Immersion in SBF up to 21 days indicated significant changes in pH, weight gain and apatite formation. Cell viability has demonstrated no cytotoxic effect and denoted that Si-BCP promoted good initial cell adhesion and proliferation. These results suggest that Si-BCP's surface roughness (164 nm) was significantly higher than BCP (88 nm), thus enhancing the adhesion and proliferation of the osteoblast.

Matched MeSH terms: Silicon Dioxide
Fulltext Aerogel Poly(butylene succinate) Biomaterial Substrate for RF and Microwave Applications

Habib Ullah M, Mahadi WN, Latef TA

Sci Rep, 2015;5:12868.
PMID: 26238975 DOI: 10.1038/srep12868

Polybutylene succinate (PBS) has become a potential candidate, similar to polypropylene (PP) and acrylonitrile butadiene styrene (ABS), for use as an organic plastic material due to its outstanding mechanical properties as well as high thermal deformation characteristics. A new composition of silica aerogel nanoparticles extracted from rice waste with PBS is proposed for use as a dielectric (εr = 4.5) substrate for microwave applications. A microstrip patch antenna was fabricated on the proposed dielectric substrate for multi-resonant ultra-wideband (UWB) applications. The performance characteristics of the proposed biomaterial-based antenna were investigated in a far-field measurement environment. The results indicate that the proposed biocompatible material-based antenna covered a bandwidth of 9.4 (2.3-11.7) GHz with stop bands from 5.5 GHz to 5.8 GHz and 7.0 GHz to 8.3 GHz. Peak gains of 9.82 dBi, 7.59 dBi, 8.0 dBi and 7.68 dBi were measured at resonant frequencies of 2.7 GHz, 4.6 GHz, 6.3 GHz and 9.5 GHz, respectively.

Matched MeSH terms: Silicon Dioxide
Fulltext Effect on Physical and Mechanical Properties of Conventional Glass Ionomer Luting Cements by Incorporation of All-Ceramic Additives: An In Vitro Study

Saran R, Upadhya NP, Ginjupalli K, Amalan A, Rao B, Kumar S

Int J Dent, 2020;2020:8896225.
PMID: 33061975 DOI: 10.1155/2020/8896225

Introduction: Glass ionomer cements (GICs) are commonly used for cementation of indirect restorations. However, one of their main drawbacks is their inferior mechanical properties.
Aim: Compositional modification of conventional glass ionomer luting cements by incorporating two types of all-ceramic powders in varying concentrations and evaluation of their film thickness, setting time, and strength. Material & Methods. Experimental GICs were prepared by adding different concentrations of two all-ceramic powders (5%, 10, and 15% by weight) to the powder of the glass ionomer luting cements, and their setting time, film thickness, and compressive strength were determined. The Differential Scanning Calorimetry analysis was done to evaluate the kinetics of the setting reaction of the samples. The average particle size of the all-ceramic and glass ionomer powders was determined with the help of a particle size analyzer.
Results: A significant increase in strength was observed in experimental GICs containing 10% all-ceramic powders. The experimental GICs with 5% all-ceramic powders showed no improvement in strength, whereas those containing 15% all-ceramic powders exhibited a marked decrease in strength. Setting time of all experimental GICs progressively increased with increasing concentration of all-ceramic powders. Film thickness of all experimental GICs was much higher than the recommended value for clinical application.
Conclusion: 10% concentration of the two all-ceramic powders can be regarded as the optimal concentration for enhancing the glass ionomer luting cements' strength. There was a significant increase in the setting time at this concentration, but it was within the limit specified by ISO 9917-1:2007 specifications for powder/liquid acid-base dental cements. Reducing the particle size of the all-ceramic powders may help in decreasing the film thickness, which is an essential parameter for the clinical performance of any luting cement.

Matched MeSH terms: Silicon Dioxide

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