Number of found documents: 597
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In vivo study of diatom assemblages using low temperature method for ESEM
Tihlaříková, Eva; Neděla, Vilém; Fránková, Markéta
2017 - English
Diatoms are the most species-rich algal group represented by 12 000 described species and are recognized as powerful bio indicators and used for water quality monitoring. Diatom taxonomy is predominantly based on the morphology of ornate silicified cell wall called frustule composed of two overlapping parts (thecae). This frustule displays intricate patterns and designs unique to each species. For these studies conventional scanning electron microscopy (SEM) was and still is widely used. This method requires cleaning of diatom frustules in strong acids and peroxides followed by conductive coating.This aggressive procedure removes protoplast and damages delicate structures. Environmental scanning electron microscopy (ESEM) brings advantages of observation of fresh diatom material that are presence of whole intact diatom cells, not only empty diatom frustules, extracellular mucilaginous diatom secrets (e.g. pads, stalks, tubes) and whole diatom assemblages directly in situ together with other algal assemblages (e.g. cyanobacteria or green algae). However, in diatom research, ESEM is used mainly for elimination of conductive coating and observation of these organisms in their native wet state adhered directly on the host plant is not yet common. The ESEM observation of native aquatic samples is usually affected with radiation damage that can be lovered by the use of special methods like the Low Temperature Method (LTM) for the ESEM. Keywords: ESEM; diatom; morphology; LTM Available at various institutes of the ASCR
In vivo study of diatom assemblages using low temperature method for ESEM

Diatoms are the most species-rich algal group represented by 12 000 described species and are recognized as powerful bio indicators and used for water quality monitoring. Diatom taxonomy is ...

Tihlaříková, Eva; Neděla, Vilém; Fránková, Markéta
Ústav přístrojové techniky, 2017

Nanopatterning of Silicon Nitride Membranes
Matějka, Milan; Krátký, Stanislav; Řiháček, Tomáš; Kolařík, Vladimír; Chlumská, Jana; Urbánek, Michal
2017 - English
Membranes are typically created by a thin silicon nitride (SIN) layer deposited on a silicon wafer. Both, top and bottom side of the wafer is covered by a thin layer of the silicon nitride. The principle of silicon nitride membranes preparation is based on the wet anisotropic etching of the bottom side of the silicon wafer with crystallographic orientation (100). While the basic procedure for the preparation of such membranes is well known, the nano patterning of thin membranes presents quite important challenges. This is partially due to the mechanical stress which is typically presented within such membranes. The resolution requirements of the\nmembrane patterning have gradually increased. Advanced lithographic techniques and etching procedures had to be developed. This paper summarizes theoretical aspects, technological issues and achieved results. The application potential of silicon nitride membranes as a base for multifunctional micro system (MMS) is also\ndiscussed. Keywords: e-beam writer; silicon nitride membranes; nano patterning; anisotropic etching Available at various institutes of the ASCR
Nanopatterning of Silicon Nitride Membranes

Membranes are typically created by a thin silicon nitride (SIN) layer deposited on a silicon wafer. Both, top and bottom side of the wafer is covered by a thin layer of the silicon nitride. The ...

Matějka, Milan; Krátký, Stanislav; Řiháček, Tomáš; Kolařík, Vladimír; Chlumská, Jana; Urbánek, Michal
Ústav přístrojové techniky, 2017

Noise behaviour of field emission cathode based on lead pencil graphite
Knápek, Alexandr; Horáček, Miroslav; Hrubý, František; Šikula, J.; Kuparowitz, T.; Sobola, D.
2017 - English
The paper describes electrical noise of experimental field emission cathodes based on “polymer” pencil leads which have a high content of hybridized carbon with a low degree of surface oxidation and silicon monoxide (SiO). Charge transport within experimental samples is evaluated based on results provided by the noise spectroscopy method. The paper also briefly describes the experimental preparation method of graphite tips based on ion milling which allow obtaining ultrasharp tips of a diameter lower than 100 nm. Keywords: field emission; lead pencil graphite; noise spectroscopy Available at various institutes of the ASCR
Noise behaviour of field emission cathode based on lead pencil graphite

The paper describes electrical noise of experimental field emission cathodes based on “polymer” pencil leads which have a high content of hybridized carbon with a low degree of surface oxidation and ...

Knápek, Alexandr; Horáček, Miroslav; Hrubý, František; Šikula, J.; Kuparowitz, T.; Sobola, D.
Ústav přístrojové techniky, 2017

Resampling in magnetic resonance spectroscopy-A less model-dependent quantitation quality assessment method
Jabłoński, Michal; Starčuková, Jana; Starčuk jr., Zenon
2017 - English
In this paper we propose a novel method for magnetic resonance spectroscopy (MRS) fitting quality assessment based on time domain resampling of acquired spectra and bootstrapping of the obtained results. The authors introduce two resampling strategies and example results are shown. The proposed method requires MRS data without averaging. Keywords: magnetic resonance spektroscopy; quantitation; fitting Quality Assessment Available at various institutes of the ASCR
Resampling in magnetic resonance spectroscopy-A less model-dependent quantitation quality assessment method

In this paper we propose a novel method for magnetic resonance spectroscopy (MRS) fitting quality assessment based on time domain resampling of acquired spectra and bootstrapping of the obtained ...

Jabłoński, Michal; Starčuková, Jana; Starčuk jr., Zenon
Ústav přístrojové techniky, 2017

Effect of gold coating on emissivity and absorptivity of Ti-6Al-4V alloy
Frolec, Jiří; Králík, Tomáš; Musilová, Věra; Urban, Pavel
2017 - English
The article provides experimental analysis of total hemispherical emissivity and absorptivity of Ti-6Al-4V alloy before and after deposition of 1-2 .pí.m gold layer. We measured their dependences on the temperature of thermal radiation (varying from 20 K to 320 K) and confronted these results with mechanically polished copper, i.e. with material known for extremely low emissivity and absorptivity. Galvanic deposition of pure gold resulted in significant lowering of original emissivity of Ti-6Al-4V bare surfaces from 15.8 percent to 3.4 percent at 300 K and from 4.1 percent to 1.1 percent at 20 K. Our findings about thermal-radiative properties have practical relevance for an improvement of a low temperature part of an ultra-high vacuum scanning probe microscope\n(UHV-SPM) designed by our group and could also be useful for other applications and low temperature systems. Keywords: cryogenics; gold films; heat transfer; thermal radiation Available at various institutes of the ASCR
Effect of gold coating on emissivity and absorptivity of Ti-6Al-4V alloy

The article provides experimental analysis of total hemispherical emissivity and absorptivity of Ti-6Al-4V alloy before and after deposition of 1-2 .pí.m gold layer. We measured their dependences on ...

Frolec, Jiří; Králík, Tomáš; Musilová, Věra; Urban, Pavel
Ústav přístrojové techniky, 2017

Role of the superconductivity in radiative heat transfer
Králík, Tomáš; Musilová, Věra; Srnka, Aleš; Fořt, Tomáš; Frolec, Jiří
2017 - English
The absorption and emission of thermal radiation by metals is related to their electrical properties that are influenced by impurities, defects and temperature. We show by some examples of measurements on common metals how different can be the thermal radiative properties. When the heat is transferred across a microscopic vacuum gap in the near field regime, it is possible to achieve a step-like change of the heat\ntransfer based on a superconducting transition. An interesting feature of this effect is the nonlinear thermal conductivity effecting a change of the sign of the differential thermal conductivity across the vacuum gap. Keywords: thermal radiation; near field; superconductivity Available at various institutes of the ASCR
Role of the superconductivity in radiative heat transfer

The absorption and emission of thermal radiation by metals is related to their electrical properties that are influenced by impurities, defects and temperature. We show by some examples of ...

Králík, Tomáš; Musilová, Věra; Srnka, Aleš; Fořt, Tomáš; Frolec, Jiří
Ústav přístrojové techniky, 2017

Parameter Optimization of Multi-Level Diffraction Gratings
Matějka, Milan; Kolařík, Vladimír; Horáček, Miroslav; Král, Stanislav
2017 - English
Originally, the e-beam lithography (EBL) is a technique for creating high-resolution black and white masks for the optical lithography. Multi-level relief structures can be also prepared using EBL patterning. Their preparation is based on the image patterning with a gradient of exposure doses. Large-area multi-level structures can be effectively prepared using the electron beam pattern generator with a variable shaped beam. We present several writing strategies. Basically, the main writing strategy uses one stamp (i.e. one elementary exposure of the shaped electron beam) per one elementary area with the same exposure dose. This simple approach is fast and flexible, however it does not guarantee optimal results. The main problem is an imperfection of the stamps (size, shape, and homogeneity). Advanced algorithms are based on multiple\nexposure of the same elementary area, the total local exposure dose is a sum of several different elementary exposures (stamps). Using these algorithms, a smoother surface of the structure can be achieved. On the other hand, the writing speed is considerably decreased. Tradeoff between the achieved parameters and the writing speed is discussed for selected set of writing strategy algorithms. Keywords: e-beam pattern generator; variable shaped beam; grayscale lithography; multi-level grating Available at various institutes of the ASCR
Parameter Optimization of Multi-Level Diffraction Gratings

Originally, the e-beam lithography (EBL) is a technique for creating high-resolution black and white masks for the optical lithography. Multi-level relief structures can be also prepared using EBL ...

Matějka, Milan; Kolařík, Vladimír; Horáček, Miroslav; Král, Stanislav
Ústav přístrojové techniky, 2017

Effect of thermal radiation on low temperature measurement for various types of temperature sensor installations
Urban, Pavel; Hanzelka, Pavel; Králík, Tomáš; Vlček, Ivan; Srnka, Aleš
2017 - English
We investigated an effect of thermal radiation (300 K) on precision of low temperature measurement of a sample holder (or sample) in an UHV SEM/SPM microscope working at range down to 20 K for various ways of temperature sensor mounting. We designed a special copper casing for installation of Lake Shore\ntemperature sensors (CernoxTM and Si diodes) encapsulated in SD packages. The sensor body is attached direct to the casing using indium solder. The current leads pertaining to the sensor are thermally anchored but electrically insulated from the casing. Quality of sensors installation in the casing was tested for various ways of mounting on a cooled plate. Insufficient thermal anchoring of electrical wires and thermal shielding were imitated. Comparative measurement was also performed with sensors in SD package mounted without\ncasing. The experiments proved that our special design of temperature sensors casing is adequate for intended application of temperature measurement of sample holder in UHV SEM/SPM microscope. In contrary, measurement precision of unprotected sensors was absolutely unsuitable. Keywords: low temperature; temperature sensor; thermal radiation Available at various institutes of the ASCR
Effect of thermal radiation on low temperature measurement for various types of temperature sensor installations

We investigated an effect of thermal radiation (300 K) on precision of low temperature measurement of a sample holder (or sample) in an UHV SEM/SPM microscope working at range down to 20 K for various ...

Urban, Pavel; Hanzelka, Pavel; Králík, Tomáš; Vlček, Ivan; Srnka, Aleš
Ústav přístrojové techniky, 2017

Nežádoucí metabolické účinky aripiprazolu v poly I:C modelu schizofrenie u potkana
Horská, K.; Rudá-Kučerová, J.; Dražanová, Eva; Pistovčáková, J.; Karpíšek, M.; Kotolová, H.; Demlová, R.; Kašpárek, T.
2017 - English
The aim of this study was to evaluate metabolic phenotype of poly I:C rat model and asses metabolic effects of chronic aripiprazole treatment with regard to complex neuroendocrine regulations of energy homeostasis. Altered lipid profile in poly I:C model was observed. Leptin and GLP-1 serum levels were significantly reduced, while ghrelin level was elevated. Our data indicate that dysregulation of adipose tissue endocrine function and gastrointestinal hormones is implicated in metabolic adverse effects of antipsychotics. Keywords: metabolic syndrome; aripiprazole; rat; poly I:C animal model Available at various institutes of the ASCR
Nežádoucí metabolické účinky aripiprazolu v poly I:C modelu schizofrenie u potkana

The aim of this study was to evaluate metabolic phenotype of poly I:C rat model and asses metabolic effects of chronic aripiprazole treatment with regard to complex neuroendocrine regulations of ...

Horská, K.; Rudá-Kučerová, J.; Dražanová, Eva; Pistovčáková, J.; Karpíšek, M.; Kotolová, H.; Demlová, R.; Kašpárek, T.
Ústav přístrojové techniky, 2017

Phyllotactic Model Linking Nano and Macro World
Horáček, Miroslav; Meluzín, Petr; Krátký, Stanislav; Urbánek, Michal; Bok, Jan; Kolařík, Vladimír
2017 - English
Recently, the arrangement of diffraction primitives according to a phyllotactic model was presented. This arrangement was used to benchmarking purposes of the e-beam writer nano patterning. The phyllotactic arrangement has several interesting properties. One of them is related with the coherence between the nanoor microscopic domain of individual optical primitives and the properties of visually perceived images crated by these structures in the macro domain. This paper presents theoretical analysis of the phyllotactic arrangement in the referred context. Different approaches enabling the creation of diffractive optically variable images are proposed. The practical part of the presented work deals with the nano patterning of such structures using two different types of the e-beam pattern generators. One of them is a system with a variable shaped beam of electrons, while the other one is a system with a Gaussian-shaped beam. E-beam writing strategies and the use of inherent spiral patterns for exposure ordering and partitioning are also discussed. Keywords: nano patterning; spiral grating structure; phyllotactic pattern; e-beam writer Available at various institutes of the ASCR
Phyllotactic Model Linking Nano and Macro World

Recently, the arrangement of diffraction primitives according to a phyllotactic model was presented. This arrangement was used to benchmarking purposes of the e-beam writer nano patterning. The ...

Horáček, Miroslav; Meluzín, Petr; Krátký, Stanislav; Urbánek, Michal; Bok, Jan; Kolařík, Vladimír
Ústav přístrojové techniky, 2017

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