National Repository of Grey Literature 58 records found  1 - 10nextend  jump to record: Search took 0.00 seconds. 
Persistent water pollutants: case of ethylenediaminetetraacetic acid in the Czech Republic
Prášek, Jan ; Šauer, Petr ; Keprtová, Karolína
Reuse and recycling of products composed of natural matter is relatively without significant environmental problems. However, recycling of products produced using modern synthetic technologies often brings new challenges. Our analysis has shown that substitution of citric acid with artificial substance of ethylenediaminetetraacetic acid causes important environmental problems. The case study carried out in the Elbe river basin shows that the ethylenediaminetetraacetic acid concentration standard has been exceeded, particularly from confluence of the Vltava and Elbe rivers. Open questions and tasks for future technological development and environmental policies are formulated, particularly the idea to replace artificial substances with nature-based ones. This would enable better introduction of circular economy ideas in the use of resources.
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Fabrication and testing of MEMS device components for micromanipulation
Binková, Petra ; Prášek, Jan (referee) ; Liška, Jiří (advisor)
This diploma thesis deals with the production and testing of MEMS devices intended for micromanipulations with a possibility of their usage in a scanning electron microscope, which includes manipulation of microobjects such as metal microparticles, microfibres or even biological samples. The first chapter contains a detailed study of microsystems and MEMS devices. The next chapter describes various types of micromanipulations, including MEMS. The third chapter deals with possible techniques of microfabrication. The fourth chapter contains experimental part of this work, in which two versions of silicon microgrippers were proposed. Considering available solutions of micromanipulators, principal and spatial limitations in the electron microscope, the piezoelectric actuator was chosen as the gripping principle. Direct write laser lithography and deep reactive ion etching were used to produce the microgrippers, and it was necessary to optimize these techniques for selected application. During the optimizations, various problems were solved, including the elimination of black silicon formation, unsuccessful etching of narrow deep structures, etc. Prototype of one of the proposed microgripper was successfully created. The manufactured micromanipulators were subsequently tested under an optical microscope. During testing, it was necessary to modify the position of the actuator in the device to ensure that the jaws of the manipulator are clamped.
Microelectromechanical through-silicon vias
Dulák, Radovan ; Hrdý, Radim (referee) ; Prášek, Jan (advisor)
Through-hole silicon vias are key technology enabling 3D system integration and thus creating compact devices. These vertical microstructures interconnect multiple layers and are also used in integrated circuits and MEMS devices. This bachelor‘s thesis focuses on the possibility of preparing these microjunctions by wet anisotropic etching and dry anisotropic etching using the deep reactive ion etching (DRIE) process for use in MEMS. The work shows preparation, etching, plating and galvanic filling of these structures. Using optical and scanning electron microscope (SEM) images, experimental tests and subsequent optimization were performed and evaluated to create a hole with a minimum size of approximately 1 m using a wet etching process and 16 m by a dry etching process. The highest achieved aspect ratio on a wafer was 15:1. In addition, the created holes were plated, galvanically filled with conductive material and electrically tested and measured.
Electrical characterization of organic electrochemical transistors
Dundr, Jakub ; Prášek, Jan (referee) ; Gablech, Imrich (advisor)
This master’s thesis is focused on electrical characterisation of PEDOT:PSS based organic electrochemical transistors, it’s electrical parameters, physical properties and principles. This thesis further includes fields of usage of the OECT, mainly usage for bioelectronics. Last part of this thesis is focused on the measurement of the OECT electrical parameters including short introduction to the equipment for measurement. The outcome of this thesis is evaluation of PEDOT:PSS overlap on gold contacts in terms of observed electrical parameters.
Nanopatterned alumina-based materials for electrochemical sensors and biosensors
Kynclová, Hana ; Hynek, David (referee) ; Trnková, Libuše (referee) ; Prášek, Jan (advisor)
The doctoral thesis is focused on basic research and development of nanostructured surfaces prepared using anodic alumina material. Various types of gold nanostructured surfaces and nanoporous aluminum membranes for electrochemical sensors and biosensors were prepared using the anodic oxidation method. Nanostructured surfaces were prepared by electrochemical anodization of aluminum material to form hexagonally arranged nanopores. Gold was then deposited into the nanoporous masks by electrochemical reduction from potassium dicyanoaurate solution using a pulse deposition method. The prepared nanostructured gold surfaces were electrochemically characterized by electrochemical impedance spectroscopy and voltammetry. Temperature stability and the effect of annealing on their electrochemical behavior at atmospheric pressure as well as in the vacuum were investigated. Then, gold nanostructures of various dimensions were prepared and the influence of their shape and dimensions on the electrochemical behavior was studied. Nanostructured surfaces were also modified with 11–mercaptoundecanoic acid, and the effect of this modification on the electrochemical results was studied. In the last part of the work, nanoporous aluminum membranes were prepared, and their permeability was studied.
Graphene as the active layer for gas detection
Zach, Pavel ; Prášek, Jan (referee) ; Gablech, Imrich (advisor)
The aim of this bachelor thesis is to sum up theoretical knowledge concerning gas detection by sensor with a graphene active layer. It is focused on principles and construction of selected sensors. Furthermore, this work describes values characterizing the measurement results. Both crystallographic and electrical properties of graphene are discussed as well. This thesis explains the methods of production of graphene and its derivatives and also gives a look into selected characterization methods for the study of graphene. Furthermore, this work describes the phenomena behind the sensor's ability to detect gas. At the end of this study, the results of gas measurements (NO2, NH3, H2 etc.) by a graphene transistor are interpreted.
Negotiating municipalities-industrial factory wastewater treatment coalition project: an economic laboratory experiment
Šauer, Petr ; Kolínský, Ondřej ; Prášek, Jan
It is often the case that municipalities and industrial plants treat their wastewater separately bringing the municipalities wastewater to be treated at the industrial wastewater treatment plant and reused by the plant creates potential for social costs saving for both the municipalities and the private firm. In an economic laboratory experiment we demonstrate that such voluntary agreement could be achieved even despite the presence of information asymmetry. This follows our previous research on win-win voluntary agreements and the role of information asymmetry. The biggest challenge remaining to be addressed is the distribution of the extra cake, which in our results is mostly seized by the private firm.
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Private subject in wastewater treatment regional coalition project: the case of chemical industry factory
Prášek, Jan ; Šauer, Petr
This paper presents a case study covering the solution to treatment of municipal wastewater originating from small villages located close to each other in a protected landscape area. A high environmental efficiency of treatment is required. Two scenarios of the technical solution are compared. In the first scenario, separate wastewater treatment plants will be built and operated in each of the villages. In the second one, sewerage networks will be built in each village and wastewater will be collected and treated in a wastewater treatment plant of a chemical factory located down the stream; the factory is planning to reconstruct and modernise its wastewater treatment plant. Analyses have shown that the second scenario is environmentally beneficial – ensuring high water quality in watercourses in the protected area, using purified water for industrial purposes primarily, and replenish the water balance and flows in dry periods. The second scenario also appears to be beneficial from a socio-economic point of view. Cost savings, appearing mostly at the side of the factory, creates space for negotiation and an agreement between these entities. The factory image will also improve if implementing the second scenario.
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Optimization of deep reactive ion etching process
Houška, David ; Hrdý, Radim (referee) ; Prášek, Jan (advisor)
This bachelor thesis deals with optimization of cryogenic and Bosch deep reactive ion etching (DRIE) processes. The thesis describes characterization of silicon etching methods, the principle of DRIE and the influence of individual parameters on the resulting etch profile. Based on the analysis of fabricated samples using scanning electron microscopy (SEM), both processes were optimized to create narrow microstructures with diameters ranging from 1 to 16 µm with the highest achieved depth-to-width ratio of 28:1 on a silicon substrate. Furthermore, surface roughness was analyzed using atomic force microscopy (AFM) and the presence of fluorine residues by X-ray photoelectron spectroscopy (XPS) in structures etched by both processes.
MEMS based energy harvesting
Klempa, Jaroslav ; Prášek, Jan (referee) ; Gablech, Imrich (advisor)
This work is dedicated to principles of energy harvesting or scavenging from free energy around us. Energy harvesting principles are described in the first part. Following chapter is devoted to description of piezoelectricity and piezoelectric materials. Next part researches already reported results on piezoelectric energy harvesters. Following chapter shows simulations on designed structures in ANSYS® Workbench. Next the fabrication of the structures is described. Measurement are made regarding to maximum generated power.

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See also: similar author names
4 PRÁŠEK, Jiří
2 Prášek, Jakub
4 Prášek, Jiří
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