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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]

Nowadays, mushrooms are widely studied due to the various bioactive substances they produce. They define their antibacterial, antifungal, antioxidant, antitumor, cytostatic and anti-inflammatory properties which are beneficial for human health. This study aimed to determine the antimicrobial activity of different (hot and cold ethanol/ dichloromethane/ hexane) extracts from the fungus species Lepista personata against two test microorganisms: Escherichia coli NBIMCC K12 407 and Bacillus subtilis NBIMCC 3562. The antimicrobial assays were performed applying the classical disc diffusion method. The sensitivity of test microorganisms was determined according to the zone of inhibition which appeared around the discs after 24 h of incubation at 30°C - 37°C. All extracts were dissolved in 200 mM dimethyl sulfoxide, which was used as a control sample. Results showed that E. coli NBIMCC K12 407 is susceptible to dimethyl sulfoxide whereas B. subtilis NBIMCC 3562 showed no growth inhibition. All mushroom extracts also showed no inhibitory activity against B. subtilis NBIMCC 3562. At the same time, only the dichloromethane extract obtained after hot extraction inhibited the growth of E. coli NBIMCC K12 407. [ABSTRACT FROM AUTHOR]

The wetlands in direct contact with large rivers, such as the connection between Srebarna Lake and the Danube River, are particularly vulnerable to heavy metals. These metals can be a serious problem due to their toxicity, long persistence and bioaccumulation in the food chain, at the top of which in the wetlands are the waterfowl. For this reason, they are extremely susceptible to the accumulation and influence of heavy metals in their bodies and it is possible to come on to accumulation of significant concentrations, leading to negative effects for them. In this regard, subjects of study in this article are soils from the reserve area. Eight soil samples were tested for pH, electrical conductivity, nutrient content and heavy metals presence. The presented results show that the soils in the area have a relatively good stock in terms of carbon (humus), Ca, Mg, K and P, and although some heavy metals and metalloids have been found, their concentrations are below the permissible normatively established values. [ABSTRACT FROM AUTHOR]

Biosensors are a promising alternative of the existing chromatographic methods as GC, HPLC, etc. They are fast, easy to use and provide fully acceptable values of monitoring like sensitivity, LOD, LOQ, etc. In order to construct an optical biosensor, AChE is immobilized as a target enzyme for оrganophosphorus pesticides (OPPs) onto new membranes synthesized by a sol-gel technology. The designed biosensensor is tested for determination of chlorpyrifos-methyl, parathion, pirimiphos-methyl and diazinon in liver samples. An appropriate method for sample preparation is also developed. The new method is validated in accordance with document SANTE/11945/2015 covering the required criteria for pesticides determination. The biosensor developed can detect levels lower than 30μg/ kg. The latter is the maximum residue limit (MRL) for pesticides in food. Km of 2,2x10-3M for acetylcholine and 4 months life-time of the biosensor are obtained. [ABSTRACT FROM AUTHOR]

N-Methyl carbamates are insecticides that inhibit acetylcholinesterase (AChE) causing same symptomatology in acute and chronic exposures. Traces of them could be found in animal tissues, milk, honey, eggs, etc. because of some foods treatment during growth. There is an increasing interest in fast screening methods for detection of different pollutant groups in the foods. Biosensors are a promising alternative of the existing chromatographic methods such as HPLC, GC, etc. They are fast, easy to use and provide fully acceptable values for the monitoring methods like sensitivity, LOD, LOQ, etc. In order to construct an optical biosensor, AChE is immobilized as a target enzyme for N-methyl carbamates on the surface of new membranes synthesized by a sol-gel technology. The designed biosensensor is tested for determination of methomyl, aldicarb, carbofuran, propoxur in liver samples. An appropriate method for sample preparation is also developed. Further, the new method is validated in accordance with document SANTE/11945/2015 covering the required criteria for N-Methyl carbamates determination. The biosensor could detect levels lower than 10 μg/kg which is the maximum residue limit (MRL) for pesticides in foods. Km of 2,2x10-3 M is calculated for acetylcholine using a 4 month life-time of a biosensor. [ABSTRACT FROM AUTHOR]

The chemical nature of carriers for enzyme immobilization plays an important role for retention of the enzyme activity and stability. Two new materials are synthesized for enzyme immobilization based on trimethoxy silane/cellulose acetate butyrate/poly (amido amine) dendrimers (TMOS/CAB/PAMAM) and methyltriethoxy silane/cellulose acetate propionate/poly (amido amine) dendrimers (MTES/CAP/PAMAM). The synthesis is carried out via the sol-gel method, which allows the preparation of porous glasses through hydrolysis and poly-condensation at a low temperature using high purity initial materials. The PAMAM dendrimers are mono-dispersive, well defined and have a developed three dimensional structure of a high functional groups concentration. The obtained materials are used to investigate the properties of immobilized enzymes such as lipoxygenase and laccase. These enzymes are widely used in industry as bleaching agents. There is also data on application of laccase and lipoxygenase in preparation of biosensors for toxic pollutants determination. Biosensors with immobilized laccase are used to determine phenolic compounds, whereas immobilized lipoxygenase is applied to biosensors formulation for determining Aflatoxin B1 presence. [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]

This paper presents the investigation of Horseradish peroxidase (HPR) immobilization on poly-(acrylonitrile-co-acrylamide) and polyamide membranes using three different regimes of a fluid movement: a turbulent, a laminar and an intermediate one. The turbulent movement of the liquid is realized through a magnetic stirrer application. The laminar flow is achieved in a microfluidic system, while the attached amount of enzymes is monitored by a quartz crystal microbalance (QCM). The third type of movement, a fluid movement in an inclined pipe with a varied angle of inclination, is realized in a laboratory made rig. We find that the type of flow influences the immobilized enzyme amount, the time of the immobilization and the structure of the immobilized film. The main conclusion is that the laminar flow favours the process of covalent immobilization most probably because of the orientation of the molecules and their movement parallel to the carrier surface. [ABSTRACT FROM AUTHOR]

A modified procedure of EN 16619:2015 method for determination of four polycyclic aromatic hydrocarbons (PAH's) was proposed. A change in internal standard and in sample preparation procedure was made for two low fat food matrices (wheat flour and smoked pork leg). As a result a new calibration was obtained with very good linearity (correlation coefficient R2 = 0.999). Recovery rates for spiked samples from both matrices were also calculated and were found in a good fit with the European legislation specifications. The average values of the recovery rates amounted to 99.32 % (1.83 % relative standard deviation) for wheat flour and 97.25 % (2.50 % relative standard deviation) for smoked pork leg. [ABSTRACT FROM AUTHOR]

Cholesterol and fatty acids are compounds with a key role in the human organism. Their levels must be strictly controlled and maintained in the human body to ensure its proper biochemical functioning. Herein, we report first steps of development of a method for cholesterol determination in food using GC/FID. The calibration, the linearity and the choice of an appropriate internal standard are discussed. The obtained correlation coefficient is R2 = 0,9992. A very good analytical yield of cholesterol 100 % is achieved following a specific procedure of sample preparation. LOQ is 50 ppm, while LOD is 15 ppm. [ABSTRACT FROM AUTHOR]

Lipases are serine hydrolases defined as triacyl glycerol acyl hydrolases (EU 3.1.1.3). The unique characteristics and biotechnological potential of lipases have led to their use in food, detergents, pharmaceuticals, etc. industry. Lipolytic enzymes can be isolated from plants, animals, bacteria, fungi and yeasts. In this work we report the synthesis, isolation and purification of an extracellular lipase from Pseudozyma antarctica NBIMCC 8340 using a three-step process. The lipase activity is analyzed by potentiometric and colorimetric method at every stage of the isolation. In order to optimize the synthesis and isolation conditions two separate experiments of fermentation process, test and real one, are realized. The isolation and separation of the lipase in our case are carried out by fractional precipitation with (NH4)2SO4, followed by purification through ultrafiltration using micro concentration tubes Sartorius VIVASPIN 6. The resulting isolate of P. antarctica lipase B is detected by SDS PAGE and analyzed for lipase activity. Preparative isolation of the enzyme in native PAGE is further conducted as a third step aiming to obtain a high purity lipase. Thus a highly purified CalB of a specific activity of 92 U/mg is obtained. [ABSTRACT FROM AUTHOR]

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The aim of this study is to covalently immobilize horse radish peroxidase (HRP) onto new hybrid membranes synthesized by the sol-gel method based on silica precursors, dendrimers and cellulose derivatives. This new system will be used for designing biosensor. For investigation of the properties of membranes, HRP was used as a modeling enzyme. Kinetic parameters, pH and temperature optimum were determined, and the structure of the membranes surface was examined. Results showed higher relative and residual activity of HRP immobilized onto membranes with cellulose acetate butyrate with high molecular weight CAB/H. This novel biosensor could offer a simple, cheap and rapid tool with enhanced sensing performance as well as having potentials to find application in medicine, pharmacy, food and process control and environmental monitoring. [ABSTRACT FROM AUTHOR]

By using sol-gel method, hybrid membranes were synthesized based on SiO2 and cellulose derivatives. Membranes showed good physical and mechanical properties as well as good biocompatibility. Onto hybrid membranes tyrosinase and horse radish peroxidase were immobilized and optical biosensor was constructed. The working principle of constructed biosensor was detection of oxygen consumption. The properties of constructed biosensors like linear range, life time and sensitivity were defined by modeling substrate -- L-3,4-dihydroxyphenylalanine. The factors affecting the constructed optical biosensors were investigated. The results showed that a multienzyme system is capable of improving the constructed biosensor properties. [ABSTRACT FROM AUTHOR]