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1
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4-amine-2-mercaptopyrimidine modified silica gel applied in Cd(II) and Pb(II) extraction from an aqueous medium

100%
Pereira A., Ferreira G., Caetano L., Castro R., Santos A., Padilha P., Castro G.
Polish Journal of Chemical Technology
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2010
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vol. 12
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issue 1
7-11
EN
This paper discusses silica surface modification by a process involving a two-step reaction: anchoring of a silylating agent, followed by an attachment of a 4-amino-2-mercaptopyrimidine molecule. The modified material (Si-BP) was successfully characterized by the FTIR spectra, which revealed amine absorption bands, and through 13C and 29Si NMR spectra, which confirm the proposed structure of the modified silica (Si-BP). Si-BP was used to extract cadmium and lead from an aqueous medium at 298 K. The Si-BP kinetics towards metal ions was very fast, i.e., about 10 minutes, although extraction was significantly impaired at pH 3. The series of adsorption isotherms were adjusted to a modified Langmuir equation and the maximum extraction capacity was 0.193 and 0.387 mmol g-1 for Cd(II) and Pb(II), respectively. An analysis of the Ø values lead to the inference that the resulting metal ligand complex was type 1:1.
2
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Change of silica luminescence due to fast hydrogen ion bombardment

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Zhurenko V. P., Kalantaryan O. V., Kononenko S. I.
Nukleonika
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2015
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vol. 60
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issue 2
289-292
EN
This paper deals with the luminescence of silica (KV-type) induced by beam of hydrogen ions with the energy of 210 keV per nucleon. An average implantation dose of up to 3.5 × 1021 cm−3 (5 × 1010 Gy) was accumulated during irradiation over an extended period. The luminescent spectra consisted of the blue band (maximum at 456 nm) and the red band (650 nm) in the visible range. It was shown that increase in the absorption dose had an effect on the silica luminescence. It was found that the most significant changes in the spectrum occurred during the dose accumulation in the region of 550–700 nm. The shape of the spectrum of the luminescent radiation in this wavelength range was affected both by the oxygen deficient centres (blue band) and non-bridging oxygen hole centers (red band). Mathematical processing of the experimental spectra permitted to identify contributions to the luminescent radiation coming from both types of defects.
3
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Coating of Ordered Large-Pore Mesoporous Silica with TiO₂ Nanoparticles and Evaluation of Its Photocatalytic Activity

100%
Haghighatzadeh A., Mazinani B., Abdolahpour Salari M.
Acta Physica Polonica A
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2017
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vol. 132
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issue 3
420-422
EN
In this work, at first large pore size SiO₂ mesostructure was prepared using amphiphilic triblock copolymer (P123) as a template, tetraethyl orthosilicate (TEOS) as Si source and hexane as micelle expander by hydrothermal procedure. Separately, a stable transparent titania sol was synthesized using titanium isopropoxide (TTIP) as titanium source. Then achieved mesoporous silica structure was stirred in the titania sol resulting in formation of a titanium dioxide anatase layer on the silica structure. The sample was characterized with wide angle X-ray diffraction, N₂ adsorption-desorption analysis, X-ray photoelectron spectroscopy, field-emission scanning electron microscopy, and energy dispersive X-ray spectroscopy maps of silicon and titanium. The photocatalytic performance of prepared composite material was evaluated using UV-vis spectroscopy as well. The prepared material showed much higher photodegradation of methyl blue (MB) than commercial P-25 which was attributed to high surface area (290 m²/g), anatase phase, small crystallite size and accessible pores.
4
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Synthesis and physicochemical characterization of silicafillers modified with octakis({3-methacryloxypropyl}dimethylsiloxy) octasilsesquioxane

100%
Szwarc-Rzepka K., Gogola N., Siwińska-Stefańska1 K., Marciniec B., Jesionowski T.
Polish Journal of Chemical Technology
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2013
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vol. 15
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issue 4
15-23
EN
Hybrid nanofillers of silica grafted with octakis({3-methacryloxypropyl}dimethylsiloxy) octasilsesquioxane were obtained by the method based on solvent evaporation with the use of both hydrated or emulsion spherical silica. Octakis({3-methacryloxypropyl}dimethylsiloxy) octasilsesquioxane was applied as a modifying agent and it was synthesized by employing the hydrosilylation reaction. The effectiveness of modification of the hybrid nanofillers obtained was verified using Fourier transform infrared spectroscopy and nuclear magnetic resonance (29Si and 13C CP MAS NMR). The products obtained were characterized by determination of their physicochemical properties and porous structure, including specific surface area, pore diameter and pore volume. Dispersion degree and particle size of the nanofillers was characterized by NIBS (Non-Invasive Back-scatter) method and laser diffraction technique, while their morphology by transmission electron microscopy.
5
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Immobilization ofAmano Lipase Aonto Stöber silica surface: process characterization and kinetic studies

100%
Zdarta J., Sałek K., Kołodziejczak-Radzimska A., Siwińska-Stefańska K., Szwarc-Rzepka K., Norman M., Klapiszewski Ł., Bartczak P., Kaczorek E., Jesionowski T.
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issue 1
EN
The immobilization of Amano Lipase A from Aspergillus niger by adsorption onto Stöber silica matrix obtained by sol-gel method was studied. The effectiveness of the enzyme immobilization and thus the usefulness of the method was demonstrated by a number of physicochemical analysis techniques including Fourier Transform Infrared Spectroscopy (FT-IR), elemental analysis (EA), thermogravimetric analysis (TG), porous structure of the support and the products after immobilization from the enzyme solution with various concentration at different times. The analysis of the process’ kinetics allowed the determination of the sorption parameters of the support and optimization of the process. The optimum initial concentration of the enzyme solution was found to be 5 mg mL-1, while the optimum time of the immobilization was 120 minutes. These values of the variable parameters of the process were obtained by as ensuring the immobilization of the largest possible amount of the biocatalyst at
6
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Fractal Features and Structural, Morphological, Optical Characteristics of Sol-Gel Derived Silica Nanoparticled Thin Films

88%
Uysal B., Pekcan Ö.
Acta Physica Polonica A
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2018
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vol. 133
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issue 5
1160-1164
EN
Nanostructured silica films using a simple and effective sol-gel spin coating technique were synthesized and the influence of ammonia/sol ratios on the particle size and thickness of this film was investigated. In addition, fractal dimensions of the prepared films were determined using the scattering response technique. The samples were characterized by atomic force microscopy and UV-vis spectroscopy. Comparing optical method and image analysis of atomic force microscopy micrographs, the fractal dimension of silica nanoparticled thin films was determined. The fractal dimensions of the films verified by atomic force microscopy analysis were found to be around 2.03 which is very close to the values (2.0358, 2.0325, and 2.0335) obtained using optical method. As a result of these findings, precise determination of the nanoparticled silica thin films fractal dimension using both optical and surface analysis methods was realized.
7
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Synthesis and entomotoxicity assay of zinc and silica nanoparticles against Sitophilus granarius (Coleoptera: Curculionidae)

75%
Rouhani M., Samih M. A., Zarabi M., Beiki K., Gorji M., Aminizadeh M. R.
Journal of Plant Protection Research
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2019
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vol. 59
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issue 1
8
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THE STUDY OF ADSORPTION AND DESORPTION OF ANTIBIOTICS ON THE SURFACE OF NANOPARTICLES

75%
Biernat P., Borak B., Meler J., Karolewicz B.
Acta Poloniae Pharmaceutica - Drug Research
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2018
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vol. 75
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issue 5
1215-1222
EN
Nanotechnology is a field that is gaining more and more importance in the modern world. It uses a particle size of between a few dozen to a few hundred nanometers, or 10-9 meters. It is noted that the use of nanospheres (balls with a diameter of from several to several hundred nm) as carriers of drugs gives an opportunity for their controlled and sustained release. (1,2) Nanospheres as a potential drug carrier for sustained release may enhance the effectiveness of antibiotics. In order to examine the effects of antibiotics with nanospheres an attempt was made to deposit on them three drugs differing in chemical structure. These were chloramphenicol, gentamicin and ceftazidime. The aim of this study was to determine the degree of adsorption of the drug on the surface of nanospheres and to examine the process of desorption from the surface of silica nanoparticles. The results of the study indicate that in the case of chloramphenicol it is essentially a process of chemisorption, and for gentamicin and ceftazidime both physical and chemical adsorption, without there being any clearly defined relationship between this two processes. The purpose of the nanospheres as drug carriers is to obtain controlled and prolonged exposure to the drug. The amount of adsorbed substance depends primarily on its structure. Ceftazidime, as the compound with the highest number of double bonds, and a large number of groups to form hydrogen bonds (carbonyl groups, amino groups), adsorbed to the greatest extent.
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