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Spinnability of PEO solutions with respect to their aging
Zelenková, Jana ; Peer, Petra ; Filip, Petr
Non - negligible portion of pol ymer commodity suffers from ageing that participates in sometimes significant changes of products attributes. Rheology represents a useful tool for a description of this process. The aim of this contribution is to evaluate possible ageing of PEO solution ( polyethylen e oxide ( M w =300,000 g/mol) dissolved in water at 10 wt.% concentration) based both on rheological characterization and on quality of electrospun fibres. Rheological measurements in steady shear and oscillatory modes were carried out using a rota tional rheometer MCR 501 (Anton Paar, Austria) equipped with the concentric cylinders geometry. The electrospinning measurements were executed with the help of a proposed laboratory device. The tip - to - collector distance attained 20 cm, applied voltage rang ed from 20 to 30 kV. The obtained electrospun fibres were analysed using a scanning electron microscope (VEGA 3, Tescan, Czech Republic). Both types of measurements were carried out in the period of several months during which the solution studied was plac ed in a dark and tempered box (25°C). The measurements indicate no ageing impact on rheological characteristics or quality of electrospun fibres. This guarantees more or less the identical quality of non - woven textiles prepared from PEO solutions regardles s of time period during which the solutions are deposited.
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Does oxidation make the organic aerosol coatings more hydrophilic? Insight from molecular dynamics study of oxidized surfactant monolayers
Roeselová, Martina ; Khabiri, Morteza ; Cwiklik, Lukasz
Organic compounds are ubiquitous in atmospheric aerosols. The morphology and structure of the organic phase affect the optical properties of the aerosols, their heterogeneous reactivity as well as their ability to nucleate cloud droplets and ice particles. It is commonly assumed that atmospheric oxidative ageing of the organic material, leading to the formation of polar groups such as carbonyl (=O), hydroxyl (-OH) and carboxylic acid (-COOH), will render the aerosol particle surfaces increasingly more hydrophilic, hence, able to take up more water. Field measurements have shown that a large fraction of the organic material found in aerosols are surface active compounds, such as fatty acids and lipids(Tervahattu, 2002 and 2005). An inverted micelle structure, with an aqueous core surrounded by an organic surfactant layer, has thus been proposed for aqueous aerosols, both marine and continental (Donaldson, 2006). While recent experiments suggest the existence of more complex structures, such as organic inclusions and surfactant lenses (Dennis-Smither, 2012), a monolayer (ML) of surface active organics on an aqueous subphase (the so called Langmuir monolayers) represents the basic model system used in laboratory studies aimed at elucidating the effect of oxidative processes on structural properties of organic coatings on aerosol particles. In our previous work, we used molecular dynamics computer simulations to study the structure and stability of oxidized phospholipid MLs (Khabiri, 2012). In this contribution, we employed the molecular dynamics simulation technique to investigate – with atomistic resolution – structural changes occuring in a fatty acid ML upon moderate degree of oxidation.
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Bayesian classification of digital images by web application
Talich, M. ; Böhm, O. ; Soukup, Lubomír
The contribution introduces web application for image classification that has been developed at the Research Institute of Geodesy, Topography and Cartography in the framework of grant project InGeoCalc (supported by Ministry of education of the Czech Republic). The web application is aimed to display, examine and classify digital image data. The data are expected to be obtained from Internet by means of Web Map Services (WMS) or from other sources (possibly non-registered). Image data from different sources can be combined and presented as composition of layers (coverage) with adjustable degrees of transparency. After gathering the data, Bayesian (supervised) classification is applied to distinguish separate regions in the image. User can choose between several classification methods and adjust pertinent parameters. Furthermore, several subsequent basic analytical tools are offered, namely computation of distances, areas or perimeters related to the classified regions, simple statistical summaries about classification results (e.g. distribution of classes, percentage of non-classified regions, etc.). The classification results and registration parameters can be saved for further use. The web application is based on common Internet standards (HTML, Javascript, SVG). The only requirement for running the application is an up-to-date Internet browser supporting SVG (Scalable Vector Graphics). Typical usage of the web application can involve land cover mapping based on satellite or aerial images. The application is available free of charge for any Internet user.
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Convexity in stochastic programming model with indicators of ecological stability
Houda, Michal
We develop an optimization model dealing with construction expenses that are prescribed as a result of the EIA (Environmental Impact Assessment) process. The process is an obligatory part of every large construction project and evaluates possible influences of the project to the environment, including population health, natural and other socio-economic aspects; the result of the process is a set of recommendation and arrangements the construction must meet. Our optimization model incorporates uncertainties in model parameters; we represent them through their probabilistic distribution. Furthermore, to overcome a problem with quantifying subjective utility function of ecological impacts, we measure them by so-called indicators of ecological stability. The resulting problem is stochastic programming problem formulated as (C)VaR model used traditionally in finance area. In our contribution we deal with convexity properties of this problem – these are especially important from the theoretical as well as from the computational point of view.
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The psychological prevention of work injuries
PAPAJOVÁ, Hana
This thesis deals with psychological prevention of work injuries. About two milion of people die worldwide as a result of work injuries and illnesses originating in work. If I think about this statistic data, I have to ask myself basic questions: what is the cause of such a high mortality in today´s over-technical time, what are the main causes of injuries and how can we anticipate them? These questions are also the main issues of this work. The first chapter deals with work injuries, particularly with the way we should proceed when it comes to such an injury - what the employer´s and employee´s duties are. Rhe next sub-chapter focuses on the responsibility for the harm of work injuries, work injuries compensation such as the earning loss substitution, smart money, specific costs connected with treatment and compensation for damage to property. The second chapter is aimed to the labour protection. Firstly, it deals with the labour protection on a general level, then with the BOZP training and related basic documents, OHSAS 18001 Certifikace systému managementu BOZP - contributions of the certification and "Safe enterprise". The last sub-chapter goes in the work inspection authorities - keeping duties given by legal formulas, activities of the work inspection authorities, the scope of their activities and the authorization of the work inspector. The third chapter is about the work injuries prevention. The first sub-chapter focuses on the employer´s duties, the next one is about mental burden and its display, also the safe demands on machines and appliances, examples of causes of work injuries and more particular principles of labour protection in the food industry. The fourth part has been created in a quantitative way. I have asked nine meat manufactories to complete a questionnaire I had made myself in a way to draw conclusions and fulfill the goals of the thesis and answer the questions set at the beginning. The company, which came out the smallest accident, I did an interview, which makes, I obtained information regarding their approach to the issue. The labour and health protection are neccessary conditions in all work branches. Every employer has a lot of duties to their employees and the goal is to provide the workplace safe and with a minimal risk of work injuries. The most important issue is to pay attention to prevention from the very beginning.
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Performance of Continuous Micro Photo Reactor – Comparison with Batch Process
Drhová, Magdalena ; Hejda, S. ; Křišťál, Jiří ; Klusoň, Petr
Utilization of the flow chemistry as well as microreactors belongs to the latest trends in chemical engineering. Continuous microreactors of various kinds can be found in the literature, for example the micromixers, micro packed beds, or micro photo reactors. In order to evaluate the benefits of microtechnology application for the given process, the performance of a particular microreactor needs to be compared with the conventional setup. This contribution presents the performance of a continuous micro photo reactor in comparison with a batch process. Two model reactions were selected: the catalyzed photooxidation of 4-chlorophenol (4-CP) and the singlet oxygen chemical quencher 9,10-dimethylanthracene (DMA) in dimethylformamide. The tests were carried out using advanced opto-chemical apparatus with a well-defined light filter corresponding to the absorption bands of the used photo catalysts.
Fulltext: content.csg -  PDF
Plný tet: SKMBT_C22012102414080 - PDF
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Thin Film Composite Membrane for Effective Raw Biogas Upgrading to Pipeline Quality Methane
Kárászová, Magda ; Vejražka, Jiří ; Veselý, Václav ; Friess, K. ; Randová, A. ; Jansen, J. C. ; Izák, Pavel
In this contribution we propose a method to upgrade biogas to the same quality of fuel standard natural gas. The latter contains more than 95 vol. % of methane. Using traditional membranes, such concentration of methane in the retentate could only be achieved using a multistep process. A recently proposed method for raw biogas purification from impurities and carbon dioxide by condensing water on swollen thin film composite membranes was found to be highly effective. The hydrophilic reverse osmosis membrane promotes the formation of a very thin selective water layer under condensing conditions below the dew point of the raw biogas feed. The large difference in permeability of the impurities in raw biogas (carbon dioxide, hydrogen sulfide) and methane through the water layer enables upgrading of raw biogas to biomethane quality in a single stage. Contrary to the classical purification processes, the proposed method does not require any biogas pretreatment, which makes this approach economically attractive. It represents an innovative approach to production of biomethane from biogas.
Fulltext: content.csg - PDF
Plný tet: SKMBT_C22012102413470 - PDF
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Process-Based Model of Mixed-Matrix Membrane
Čapek, P. ; Hejtmánek, Vladimír ; Veselý, M. ; Sysel, P. ; Kočiřík, Milan ; Brabec, Libor ; Zikánová, Arlette ; Bernauer, B. ; Fíla, V.
The focus of this contribution was on the formulation and verification of a process-based model of the mixed-matrix membrane that consisted of the polyimide matrix synthesized from the monomers 4,4’-(hexafluoroisopropylidene)diphtalic anhydride and 4,4’-oxydianiline, and silicalite-1. When a solution of a polyimide precursor in N,N-dimethylformamide was ready, silicalite-1 particles were dispersed in the solution and the dispersion was subsequently cast on a Teflon support plate. An initial mass ratio of silicalite-1 and polyimide was about 1:1. After solvent removal, the films were heated in subsequent steps up to 230°C for two hour. From a process-based model point of view, a key operation of the entire synthesis was slow sedimentation of silicalite particles in the viscous solution. Preliminary observation of 2D cuts through the solid membrane in a scanning electron microscope revealed that there were a lot of contacts among the silicalite particles. Therefore, a sequential (ballistic) deposition algorithm, well representing sedimentation in a low-energy environment, was used to create an off-lattice model of spatial distribution of the silicalite particles in the polyimide matrix.
Fulltext: content.csg - PDF
Plný tet: SKMBT_C22012102413461 - PDF
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Changes in Ion Exchanger Catalysts after More than 10 Year Time-on-Stream
Jeřábek, Karel ; Hanková, Libuše ; Holub, Ladislav ; Slavík, H.
In this contribution will be reported results of examination of a series of industrial ion exchanger catalysts samples exposed to the environment of catalytic reactor in process of esterification of acrylic acid with methanol for more than 10 years. There was evaluated their acid capacity, swelling and using inverse steric exclusion chromatography (ISEC) also their morphology in water-swollen state. For comparison, similarly were evaluated also reference samples of the same but virgin ion exchangers.
Fulltext: content.csg - PDF
Plný tet: SKMBT_C22012102413430 - PDF
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