41 research outputs found

    A magyar folyóiratok digitalizálása, az összehangolás lehetőségei, digitális átállás

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    A zene, a tévé után megkezdődött a sajtó internetre, digitális médiára költözése is, sőt, ez a folyamat már évek óta tart. A továbbiakban a sajtó fogalmát tágan, a könyvtárosok számára az időszaki kiadvány fogalmával azonosítom. Digitális formában a különböző sajtótermékek a fizikai korlátoktól, országhatároktól függetlenül korlátlan számban, a földgolyó majdnem bármely részén hét nap 24 órában elérhetőek. A hordozható digitális olvasó eszközöknek köszönhetően a digitális információk már nemcsak a zárt szobákban, íróasztalnál lévő PC-ken olvashatóak, hanem a nyílt tereken, közlekedési eszközökön, kollégiumokban vagy akár a parkokban is

    The southernmost occurrence of the Striated Scops Owl critical evaluation of Egyptian records of the species

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    Abstract The first fully documented record of Striated Scops Owl from the African continental part is presented. The status of the species in Egypt and the region is presented, with discussions on the possible misidentification of the species level

    Ultra Wideband-based wireless synchronization of IEEE 1588 clocks

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    Time-Sensitive Networking (TSN) requires clock synchronization superior to the well-known Network Time Protocol (NTP). The IEEE 802.1AS-2020 used for synchronization in TSN networks is based on the IEEE 1588-2019 standard (also known as Precision Time Protocol, PTP) defines methods and tools to perform sub-microsecond time synchronization over vari- ous communication channels. However, the IEEE 1588 implementation is commonly used with wired communication protocols, although there are use cases that could gain an advantage from a wireless solution. This paper investigates the possibility of PTP clock synchronization through wireless Ultra Wideband (UWB) communication. UWB excels where other wireless technologies are lacking: it provides high accuracy timestamping even if multipath propagation is present. The method is evaluated using commercial, well-accessible cheap hardware, resulting in the order of 10-nanosecond accuracy. The paper also highlights the main error components and requirements for improving wireless PTP synchronization

    False Morphology of Aerogels Caused by Gold Coating for SEM Imaging

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    The imaging of non-conducting materials by scanning electron microscopy (SEM) is most often performed after depositing few nanometers thick conductive layers on the samples. It is shown in this work, that even a 5 nm thick sputtered gold layer can dramatically alter the morphology and the surface structure of many different types of aerogels. Silica, polyimide, polyamide, calcium-alginate and cellulose aerogels were imaged in their pristine forms and after gold sputtering utilizing low voltage scanning electron microscopy (LVSEM) in order to reduce charging effects. The morphological features seen in the SEM images of the pristine samples are in excellent agreement with the structural parameters of the aerogels measured by nitrogen adsorption-desorption porosimetry. In contrast, the morphologies of the sputter coated samples are significantly distorted and feature nanostructured gold. These findings point out that extra care should be taken in order to ensure that gold sputtering does not cause morphological artifacts. Otherwise, the application of low voltage scanning electron microscopy even yields high resolution images of pristine non-conducting aerogels

    Synthesis and Stabilization of Support-Free Mesoporous Gold Nanoparticles

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    Porous gold nanoparticles (PGNs) are usually prepared in an immobilized form on a solid substrate, which is not practical in many applications. In this work, a simple method is reported for the preparation and stabilization of mesoporous gold particles of a few hundred nanometers in size in aqueous suspension. Nanoparticles of Ag-Au alloy were fabricated on CaF 2 and Si/SiO 2 substrates by the solid-state dewetting method. Silver was selectively dissolved (dealloyed), and the resulting porous gold nanoparticles were chemically removed from the substrate either in a concerted step with dealloying, or in a subsequent step. Nitric acid was used for the one-step dealloying and detachment of the particles from CaF 2 substrate. The consecutive use of HNO 3 and HF resulted in the dealloying and the subsequent detachment of the particles from Si/SiO 2 substrate. The PGNs were recovered from the aqueous suspensions by centrifugation. The Au content of the suspensions was monitored by using elemental analysis (ICP-OES), and recovery was optimized. The morphology and the optical characteristics of the support-free PGNs were analyzed by scanning electron microscopy (SEM), dynamic light scattering spectroscopy (DLS), and near-infrared spectrophotometry (NIR). The obtained PGNs are spherical disk-shaped with a mean particle size of 765 ± 149 nm. The suspended, support-free PGNs display an ideally narrow dipole plasmon peak at around 1450 nm in the NIR spectral region. Thus, the new colloidal PGNs are ideal candidates for biomedical applications, for instance photothermal therapy
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