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According to the European Agency for Safety and Health at Work (EU - OSHA) and the Roadmap on Carcinogens about 120,000 work - related cancer cases occur each year as a result exposure to carcinogens at the workplace in the EU, leading to approximately 80,000 fatalities annually. Occupational risk assessment is used as a criterion for occupational safety. At the cement manufacturing sector, it was revealed that the main hazard is exposure to carcinogen substances such as respirable crystalline SiO2. In the present work, two methods were used for risk assessment in a cement production enterprise: the classical Fine - Kinney method and Flexible risk assessment method developed by Reinhold and Tint. The results of the joint application of these two methods show the advantages and disadvantages of each of them and point to the need to combine more than one method to effectively cover aspects of risk assessment. It was made the evaluation of applied existing control measures, as well as new measures for better protection have been proposed. [ABSTRACT FROM AUTHOR]

In the present paper the cytotoxicity of series of sol-gel based copper doped SiO2/HPC composites on lung cancer cell line (A549) and primary human umbilical cord endothelial cells (HUVEC) was investigated. Hydroxypropyl cellulose (HPC), tetraethyl ortosilicate (TEOS) were used for preparation of amorphous matrix in which the copper was added as Cu(NO3)2 *3H2O or CuSO4*5H2O in concentration range of 0 - 5 wt. %. We observed that the composite materials at low concentration of Cu (0.5 wt. %) showed no toxic effects on both cell types. The composite material with CuSO4*5H2O was found relatively more toxic, and furthermore, cancer cells are more sensitive to the copper concentration increase to non-cancer cells. The concentration of Cu ions of 2.5 and 5 wt. % were toxic to both cancer and non-cancer cells at 24th hour. At 72th hour of incubation some restoration of cell viability was observed. [ABSTRACT FROM AUTHOR]

The present paper reports an investigation of the antibacterial activity of sol-gel derived silica/hydroxypropyl cellulose zinc doped nanocomposites. The thermal analysis shows that the crosslinking between cellulose ether and zinc ions is more thermally stable than the crosslinking of the precursors in the matrix. The optical investigation and the transmission electron microscopy (TEM) observation verify the existence of nano-dimentional zinc particles. The antibacterial properties of the composites are investigated by measuring the inhibition zones formed around the materials of a different zinc content in presence of reference strains of Gram-positive bacteria - Bacillus subtilis 3562 and Gramnegative bacteria - Escherichia coli K12 and by calculating the growth decrease percentage. [ABSTRACT FROM AUTHOR]

The study focused on sol-gel synthesis of biopolymer-silica hybrids further used as materials for laccase immobilization. Silica was obtained from tetraethyl orthosilicate (TEOS), while pectin, derived from citrus fruits, was used as a biopolymer. The structure of the hybrids obtained was investigated by X-ray diffraction, Fourier transform infrared spectroscopy, Scanning electron microscopy and BET analysis. The results provided to conclude that the interaction between SiO2 network and the polysaccharide proceeding via H-bonds formation was successful. Laccase was immobilized by cross-linking, while the degradation ability was tested against several dyes - Rhodamine B, Methyl orange and Malachite green. The most effective decolorization was reached for Malachite green and Methyl orange. [ABSTRACT FROM AUTHOR]

Abstract: Amorphous hybrid materials with participation of water soluble biopolymer (pectin from apple-AP) and silica derived from tetraethoxy silane (TEOS) were synthesized by sol–gel method. The influence of biopolymer content was determined. The principles of the hybrids formation were developed using structural data from Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), Differential thermal analysis (DTA/TG), and 13C-Nuclear magnetic resonance (13C-NMR) analysis. The most probable model of interaction between pectin and silica network in the hybrid materials were proposed. It has been found that the reaction between the organic and the inorganic components was performed by depolymerization of the intermolecular H-bonds. The formation of new H-bonds between silica and pectin was supposed.Graphical abstract: [ABSTRACT FROM AUTHOR]

Three types of silica hybrid nanomaterials, doped with silver, were studied for their antifungal effect against fungi Penicillium chrysogenum strain 2303. The hybrid nanomaterials based on SiO2 and cellulose ethers - hydroxypropyl cellulose, hydroxypropylmethyl cellulose and carboxymethyl cellulose, and silver were prepared by sol-gel method. The antifungal effect was quantified against P. chrysogenum 2303 based on the inhibition zone measurement by the agar diffusion test. The results showed that the hybrid nanomaterials containing hydroxypropylmethyl cellulose, doped with the highest silver concentration of 2.5 mass % Ag, have the most prominent antifungal effect towards the fungi in comparison to the other nanomaterials. [ABSTRACT FROM AUTHOR]

Antimicrobial silica hybrid materials, based on tetraethyl orthosilicate, cellulose derivates (hydroxypropyl cellulose and hydroxypropylmethyl cellulose) and silver have been prepared by the sol-gel method. The content of cellulose ethers was 5 mass % and the silver concentration varied from 0.5 to 2.5 mass %. The antifungal effect was quantified against Asperillus niger based on the inhibition zone measurement in the diffusion test and by determination of growth inhibitory effect of the synthesized hybrid materials. The results showed that the hybrid materials have a bactericidal and bacteriostatic effect against used molds and therefore could find potential application in biotechnology and biomedical science. [ABSTRACT FROM AUTHOR]

Methylcellulose (MC) / SiO organic / inorganic hybrid materials have been prepared from MC and methyltriethoxysilane or ethyltrimethoxysilane, and characterized by XRD, FTIR and AFM. XRD showed peak shifts. FTIR shows intermolecular hydrogen bonding between MC and SiO. AFM depicts surface roughness which depends on the silica precursor and MC content. [Figure not available: see fulltext.] [ABSTRACT FROM AUTHOR]

New silica hybrid materials containing tetraethoxy siloxane (TEOS) as inorganic precursor and hydroxypropyl cellulose (HPC) as an organic compound were prepared. The quantity of organic substance was 5 and 50 wt% to silica. The structure of obtained hybrids was investigated by FT-IR and SEM analysis. The synthesized hybrid materials were applied as matrices for cells immobilization by attachment of filamentous yeast Trichosporon cutaneum R57. This strain showed considerable ability to remove manganese ions from aqueous solutions. The experimental data on the equilibrium specific uptake with free strain cells were used to plot the adsorption isotherm. Kinetic experiments on biosorption of manganese ions with immobilized cells were performed at Mn2+ initial concentrations 275 and 550 mg/L. These values were selected based on the free strain cells performance shown by the adsorption isotherm. A pseudo second order kinetic model was employed to fit the experimental data. Higher specific uptake was established with immobilized cells and higher content of HPC in the immobilization material. [ABSTRACT FROM AUTHOR]

Antibacterial SiO 2 hybrid materials based on tetraethyl orthosilicate (TEOS), hydroxypropylmethylcellulose (HPMC) and silver were prepared by the sol-gel method. The content of cellulose derivate was 5 wt% and the silver concentration varied from 0.5 wt% to 2.5 wt%. The amorphous nature, morphology and antibacterial behaviour were studied. Fourier transform infrared (FTIR) spectra of the hybrids showed characteristic peaks for SiO 2 network. Scanning electron microscope (SEM) analysis confirmed the formation of spherically shaped silver nanoparticles with a size of 30 nm on the matrix surfaces. Bacillus subtilis and Escherichia coli K12 were used as model microorganisms. The hybrid materials demonstrated bacteriostatic and bactericidal effect on the tested bacteria. Highest sensitivity to the obtained hybrids was observed in B. subtilis with significant lag-phase delay and biggest inhibition zone sizes.