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Blaze Gratings with a Ribbed Back Slope
Krátký, Stanislav; Meluzín, Petr; Horáček, Miroslav; Kolařík, Vladimír; Matějka, Milan; Chlumská, Jana; Král, Stanislav
2017 - English
Binary relief phase-modulated gratings provide symmetrical diffraction of the incoming light beam. Asymmetrical gratings, e.g. asymmetrical triangular blazed gratings, are characteristic by an asymmetrical diffraction behavior, where one of the first diffraction orders is more important than the other one. Electron beam lithography is a suitable and flexible tool for patterning of such kind of gratings. High quality results can be readily obtained when the period of the grating is relatively large and the relief depth is relatively low, this is the case of gratings with a small blaze angle. As the blaze angle increases, the quality of result suffers from several patterning-related issues. One of the problems is a reflection of the incoming light beam from the back slope (anti-blaze facet) of the blaze grating. We propose a novel configuration, with a ribbed modulation of the back slope. This modulation is perpendicular to the direction of the grating grooves. This paper presents an analysis of the proposed blazed grating configuration. E-beam pattern generators were used to prepare a few\nsamples of blaze gratings with a ribbed back slope. One part of the experiment was performed with a Gaussianshaped beam and another one with the variable-shaped beam. Results of the experiment are presented.\nFinally, we discuss the optical performance of two blaze gratings with similar parameters, one of them is with the flat back slope and another one is with the ribbed back slope.
Keywords:
nano patterning; blazed diffraction grating; Gaussian-type beam; variable-shaped beam; electron beam writer
Available at various institutes of the ASCR
Blaze Gratings with a Ribbed Back Slope
Binary relief phase-modulated gratings provide symmetrical diffraction of the incoming light beam. Asymmetrical gratings, e.g. asymmetrical triangular blazed gratings, are characteristic by an ...
Hemodynamic modelling in the calf — A pilot study
Matějková, M.; Jurák, Pavel; Soukup, L.; Halámek, Josef; Viščor, Ivo; Langer, P.; Vondra, Vlastimil
2016 - English
With increasing age, the cardiovascular system loses its efficiency. The goal of this work was to investigate the hemodynamic system response to a head-up tilt test in two groups of different aged people. We used a model for describing this response in the right calf based on a non-invasive, non-occlusive, bioimpedance signal measurement technique. A decrease in the bioimpedance value in the calf during the head-up tilt test is associated with the accumulation of blood in the calf, which can be expressed by a model parameter. Subjects were examined in both a head-up tilt test and a supine position. 50 healthy non-smoking volunteers were divided into two groups according to age. The impedance signal during the tilt test for each subject was fitted by a model exponential function: Z0 model EF(t) =A exp(-t/B)+C, where Z0 model EF(t) is the calculated model of electrical impedance in the calf by an exponential function, A is the amplitude of impedance change, B is the time constant of the impedance decrease, C is the value of the steady state after the tilt test and t denotes time. A lower time constant B shows a faster filling of the vascular system in the investigated part. The Mann-Whitney test (p-value<;0.005) revealed that the time constant B for the older group was significantly lower than for the young group (145.24+/- 80.28 vs. 239.23+/-136.59 sec.). A lower time constant value means a faster response to blood filling in the lower limbs and directly reflects decreased vessel elasticity. This time constant was lower in the older group. The results show increased vessel stiffness in old age and could lead to a non-invasive evaluating the cardiovascular system state.
Keywords:
impedance; bioimpedance; blood; biomedical monitoring
Available at various institutes of the ASCR
Hemodynamic modelling in the calf — A pilot study
With increasing age, the cardiovascular system loses its efficiency. The goal of this work was to investigate the hemodynamic system response to a head-up tilt test in two groups of different aged ...
Scanning transmission microscopy at very low energies
Müllerová, Ilona; Mikmeková, Eliška; Konvalina, Ivo; Frank, Luděk
2016 - English
To operate down to units of eV with a small primary spot size, a cathode lens with a biased specimen was introduced into the SEM. The reflected signal, accelerated secondary and backscattered electrons, is collected by detectors situated above the specimen.\nWhen we insert a detector below the specimen, the transmitted electron signal can also be used for imaging down to zero energy. Fig. 1 also shows an example of the simulated signal trajectories of electrons that impact on the detector of reflected electrons, based on an Yttrium Aluminium Garnet (YAG) crystal, and trajectories of electrons transmitted through the specimen and incident on a semiconductor detector based on the PIN structure.
Keywords:
electron microscopy; SEM
Available at various institutes of the ASCR
Scanning transmission microscopy at very low energies
To operate down to units of eV with a small primary spot size, a cathode lens with a biased specimen was introduced into the SEM. The reflected signal, accelerated secondary and backscattered ...
Optimal X-ray detection for thin samples in low-energy STEM
Rozbořil, Jakub; Oral, Martin; Radlička, Tomáš
2016 - English
In many applications it is desirable to perform energy-dispersive X-ray spectroscopy (EDS) on very thin samples at low primary beam energies in a STEM. Thin samples, or lamellae, with the thickness of about 10 nm, are mostly prepared in focused ion beam instruments (FIBs), and they are used to evaluate experiments in the development of thin films and coatings, in the semiconductor industry, and in other applications. EDS then provides a map of different chemical elements or compounds in the sample, obtained by scanning the electron beam in a raster. Often the qualitative composition is known as a limited set of materials and only their distribution on the sample is to be determined. For large batches of samples fast measurements are desired to maximize utilization of expensive equipment. In this study we found a method to minimize the time needed to reliably acquire an elemental map by determining the optimal detector placement and the minimal necessary primary electron dose per pixel.
Keywords:
electron microscopy; EDS; STEM
Available at various institutes of the ASCR
Optimal X-ray detection for thin samples in low-energy STEM
In many applications it is desirable to perform energy-dispersive X-ray spectroscopy (EDS) on very thin samples at low primary beam energies in a STEM. Thin samples, or lamellae, with the thickness of ...
Statistics-based Diagnostics of Brain Tumors
Marcon, P.; Bartušek, Karel; Dohnal, P.; Širůčková, K.
2016 - English
Currently, the increasing number of reported cancer cases has become a serious indicator of persisting low curability rates characterizing certain prominent diseases. An early tumor diagnosis constitutes a vital prerequisite for any potentially successful therapy, in this context, the present paper discusses the improvement of accuracy in the overall diagnostics related to brain tumors. The proposed measures include, for example, maximizing the use of image modifications and decreasing the radiation doses received by a patient's body. The wider project is centered on the diagnostics of pathological tissues in the brain, it describes and compares the classification and identification of particular brain tumors. For the given purpose, images were acquired via magnetic resonance tomography.
Keywords:
brain tumors; statistic diagnostics
Available at various institutes of the ASCR
Statistics-based Diagnostics of Brain Tumors
Currently, the increasing number of reported cancer cases has become a serious indicator of persisting low curability rates characterizing certain prominent diseases. An early tumor diagnosis ...
Large-area gray-scale structures in e-beam writer versus area current homogeneity and deflection uniformity
Kolařík, Vladimír; Horáček, Miroslav; Matějka, Milan; Krátký, Stanislav; Bok, Jan
2016 - English
The high stability and good current homogeneity in the spot of the e-beam writer is crucial to the exposure quality, particularly in the case of large-area structures when gray-scale lithography is used. Even though the deflection field distortion is calibrated regularly and beam focus and beam astigmatism is dynamically corrected over the entire deflection field,\nwe can observe disturbances in the exposed relief for both nowadays types of e-beam writers, the shaped e-beam writing system and the Gaussian e-beam writing system. A stable and homogeneous angular current density distribution in the spot is important especially in the case of shaped e-beam lithography systems. A non-homogeneity of the spot over deflection field is seen alongside the field boundaries of both lithography systems.
Keywords:
e-beam writer; Gaussian e-beam writing system
Available at various institutes of the ASCR
Large-area gray-scale structures in e-beam writer versus area current homogeneity and deflection uniformity
The high stability and good current homogeneity in the spot of the e-beam writer is crucial to the exposure quality, particularly in the case of large-area structures when gray-scale lithography is ...
Principal component analysis of Raman spectroscopy data for determination of biofilm forming bacteria and yeasts
Šiler, Martin; Samek, Ota; Bernatová, Silvie; Mlynariková, K.; Ježek, Jan; Šerý, Mojmír; Krzyžánek, Vladislav; Hrubanová, Kamila; Holá, M.; Růžička, F.; Zemánek, Pavel
2016 - English
Many microorganisms (e.g., bacteria, yeast, and algae) are known to form a multi-layered structure composed of cells and extracellular matrix on various types of surfaces. Such a formation is known as the biofilm. Special attention is now paid to bacterial biofilms that are formed on the surface of medical implants, surgical fixations, and artificial tissue/vascular\nreplacements. Cells contained within such a biofilm are well protected against antibiotics and phagocytosis and, thus, effectively resist antimicrobial attack.\nA method for in vitro identification of individual bacterial cells as well as yeast colonies is presented. Figure 1 shows an an example of the biofilm formed by Staphylococcus epidermidis bacteria and Candida parapsilosis yeasts known for forming biofilms. The\npresented method is based on analysis of spectral “Raman fingerprints” obtained from the single cell or whole colony, see figure 2(top). Here, Raman spectra might be taken from the biofilm-forming cells without the influence of an extracellular matrix or directly form the bacterial/yeast colony.
Keywords:
electron microscopy; biofilm; Raman spectra
Available at various institutes of the ASCR
Principal component analysis of Raman spectroscopy data for determination of biofilm forming bacteria and yeasts
Many microorganisms (e.g., bacteria, yeast, and algae) are known to form a multi-layered structure composed of cells and extracellular matrix on various types of surfaces. Such a formation is known as ...
Single particle analysis of size-segregated aerosol in Prague city center
Marvanová, S.; Skoupý, Radim; Kulich, P.; Bendl, J.; Hovorka, J.; Machala, M.
2016 - English
Particulate matter (PM) is omnipresent pollutant in the ambient air known to cause cardiovascular and respiratory diseases (WHO 2004). Recently, outdoor air pollution and particulate matter in outdoor air pollution were classified as carcinogenic to humans, Group 1 (IARC 2015). Especially, ambient PM of aerodynamic diameter < 100 nm, ultrafine particles, appears to be of great importance due to its high specific surface area and high number concentration (Hughes et al. 1998). Ultrafine particles also easily enter and are being transferred in organisms, and interact with cells and subcellular components (Oberdorster et al. 2005). As the evidence of ultrafine PM significance increased, size-fractionated PMs sampled by various cascade impactors have been employed into the toxicological studies on cell cultures or isolated cells, using the organic extracts of size-fractionated PMs (Topinka et al. 2013, Topinka et al. 2015) or directly the size-fractionated particles (Becker et al. 2003, Ramgolam et al. 2009, Reibman et al. 2002, Loxham et al. 2013, Jalava et al. 2006, Thomson et al. 2015, Jalava et al. 2015). The aim of this study was to evaluate shape and composition of size-segregated aerosol particles, sampled by high volume cascade impactor, using electron microscopy and energy dispersive X-ray spectroscopy (EDX).
Keywords:
urban atmospheric aerosol; size-fractionated; electron microscopy; energy dispersive X-ray spectroscopy
Fulltext is available at external website.
Single particle analysis of size-segregated aerosol in Prague city center
Particulate matter (PM) is omnipresent pollutant in the ambient air known to cause cardiovascular and respiratory diseases (WHO 2004). Recently, outdoor air pollution and particulate matter in outdoor ...
Biventricular pacing optimization by means of the dyssynchrony parameter
Jurák, Pavel; Leinveber, P.; Halámek, Josef; Plešinger, Filip; Postránecká, T.; Lipoldová, J.; Novák, M.
2016 - English
To improve Cardiac Resynchronization Therapy (CRT), different interventricular delay (VVD) settings can be used. However, relatively small VVD induced hemodynamic changes cannot be measured by standard echocardiographic methods. The QRS complex duration (QRSd) is mostly the main criterion. Here we introduce a new dyssynchrony parameter (DYS) that is able to more accurately detect improved electrical synchrony. Methods: 12-lead 5 kHz ECG during 3-10 minute rest period was measured in 46 patients with CRT OFF and CRT ON with VVD 0 ms (CRT0) and -20 ms (CRT20). We detected QRSd and the dyssynchrony parameter DYS as the time difference between 500-1000 Hz averaged envelopes positions in the V1 and V6 leads in the QRS complex region. Results: 32 of 46 patients had a positive CRT response manifested by QRSd shortening and a DYS decrease. 28 of 32 patients had a positive LV pre-excitation effect: additional QRSd shortening of 4.7+/-.9 ms and a DYS decrease of 12.6+/-7.5 ms. The correlation coefficient of QRSd and DYS changes (CRT 0 vs CRT 20) was 0.23 and indicates information diversity. The DYS parameter differs from QRSd and provides a significantly higher response to VVdelay changes (p <; 0.001).
Keywords:
cathode ray tubes; optimization; electrocardiography; cardiology; medical treatment; hemodynamics
Available at various institutes of the ASCR
Biventricular pacing optimization by means of the dyssynchrony parameter
To improve Cardiac Resynchronization Therapy (CRT), different interventricular delay (VVD) settings can be used. However, relatively small VVD induced hemodynamic changes cannot be measured by ...
Very low energy STEM/TOF system
Daniel, Benjamin; Radlička, Tomáš; Piňos, Jakub; Frank, Luděk; Müllerová, Ilona
2016 - English
Scanning low energy electron microscopes (SLEEMs) have been built at ISI for over 20 years, either by modification of commercially available SEMs with a cathode lens or completely self-built in case of a dedicated ultra-high vacuum scanning low energy electron microscope (UHV SLEEM). Recently, the range of detection methods has been extended\nby a detector for electrons transmitted through ultrathin films and 2D crystals like graphene. For a better understanding of interaction between low energy electrons and solids in general, and the image contrast mechanism in particular, it was considered useful to measure the energy of transmitted electrons. This allows a better comparison with simulations, which suffer from increasing complexity due to a stronger interaction of electrons with the density of states at low energies.
Keywords:
elecvtron microscopy; SLEEM; UHV SLEEM
Available at various institutes of the ASCR
Very low energy STEM/TOF system
Scanning low energy electron microscopes (SLEEMs) have been built at ISI for over 20 years, either by modification of commercially available SEMs with a cathode lens or completely self-built in case ...
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