The differences in place perception: conditionings and links in time and space

This thesis deals with the topic of place as one of the most important concepts of human geography. The term place is examined from the perspective of social constructivism. In the first part the thesis focuses on the term place, place perception, space perception and place identity. Those and other important terms are discussed based on scholar literature considering the terms. In the second part of this thesis changes of place identity are analyzed using the example of Zbuzany, a suburban village of Prague with its space dynamically grounds. Old maps and aerial photos are used for observation of the changes within the area. Also, the main phases of space development are defined. The third part of this thesis uncovers the symbolic space using semi-structured interviews conducted with six respondents from three age groups representing different generations. The interviews were analyzed and the differences in sense of place and space among generations were proved.Tato práce se zabývá jedním z nejpodstatnějších konceptů humánní geografie, totiž problematikou místa. Místo je v ní nahlíženo optikou sociálního konstruktivismu. V první části se věnuje především percepcí místa a jeho identitou, tyto a další důležité pojmy jsou kriticky diskutovány na základě odborné literatury, která se touto problematikou zabývá. Ve druhé části se věnuje proměnám identity místa na příkladě dynamicky se měnícího se prostoru obce Zbuzany, která se nachází v suburbáním zázemí Prahy. Proměny jsou sledovány na základě starých map a leteckých snímků daného území a byly vymezeny hlavní etapy proměn zástavby na území obce. Ve třetí části na základě polostrukturovaných rozhovorů s rezidenty obce práce odhaluje symbolickou vrstvu její krajiny. Rozhovory byly vedeny s šesti respondenty, kteří zastupovali tři různé generace residentů. Analýzou těchto rozhovorů byly prokázány rozdíly ve vnímání místa jednotlivými generacemi.Katedra sociální geografie a regionálního rozvojeDepartment of Social Geography and Regional DevelopmentFaculty of SciencePřírodovědecká fakult

Tunable Energy Level Alignment in the Multilayers of Carboxylic Acids on Silver

The precise energy level alignment between a metal electrode and an organic semiconductor is required to reduce contact resistance and enhance the efficiency of organic-semiconductor-based devices. One of the ways is to include interlayers that mediate the energy level alignment, i.e., charge injection layers (CILs). Here we introduce the monolayer thick CILs based on the aromatic carboxylic acids that can induce the energy level shift in the subsequent layers by up to 0.8 eV. By gradual chemical transformation of the as-deposited molecules, we achieve a highly tunable energy level shift in the range of 0.5 eV. We reveal that the position of both the work function and energy-level position in the CIL increases linearly with the density of induced dipoles. The energy level position of subsequent layers changes in the same way as the CIL. Our results thus connect the energy alignment quantities, i.e., energy level positions of both CIL and subsequent layers and sample work function. The high tunability would allow precise tuning of the active layers deposited on the CIL, which marks the path towards efficient charge injection layers on metal electrodes

Implications for behavior of volatile elements during impacts—Zinc and copper systematics in sediments from the Ries impact structure and central European tektites

This study has been funded through the Czech Science Foundation project 13-22351S. Paul Savage was supported by the Marie Curie IOF ‘Isovolc.’ Frederic Moynier is grateful to the European Research Council under the European Community's H2020 framework program/ERC grant agreement # 637503 (Pristine) and the Agence Nationale de la Recherche for a chaire d'Excellence Sorbonne Paris Cité (IDEX13C445), and for the UnivEarthS Labex program (ANR-10-LABX-0023 and ANR-11-IDEX-0005-02). Parts of this work were supported by IPGP multidisciplinary program PARI, and by Region Île-de-France SESAME Grant no. 12015908.Moldavites are tektites genetically related to the Ries impact structure, located in Central Europe, but the source materials and the processes related to the chemical fractionation of moldavites are not fully constrained. To further understand moldavite genesis, the Cu and Zn abundances and isotope compositions were measured in a suite of tektites from four different substrewn fields (South Bohemia, Moravia, Cheb Basin, Lusatia) and chemically diverse sediments from the surroundings of the Ries impact structure. Moldavites are slightly depleted in Zn (~10–20%) and distinctly depleted in Cu (>90%) relative to supposed sedimentary precursors. Moreover, the moldavites show a wide range in δ66Zn values between 1.7 and 3.7‰ (relative to JMC 3-0749 Lyon) and δ65Cu values between 1.6 and 12.5‰ (relative to NIST SRM 976) and are thus enriched in heavy isotopes relative to their possible parent sedimentary sources (δ66Zn = −0.07 to +0.64‰; δ65Cu = −0.4 to +0.7‰). In particular, the Cheb Basin moldavites show some of the highest δ65Cu values (up to 12.5‰) ever observed in natural samples. The relative magnitude of isotope fractionation for Cu and Zn seen here is opposite to oxygen-poor environments such as the Moon where Zn is significantly more isotopically fractionated than Cu. One possibility is that monovalent Cu diffuses faster than divalent Zn in the reduced melt and diffusion will not affect the extent of Zn isotope fractionation. These observations imply that the capability of forming a redox environment may aid in volatilizing some elements, accompanied by isotope fractionation, during the impact process. The greater extent of elemental depletion, coupled with isotope fractionation of more refractory Cu relative to Zn, may also hinge on the presence of carbonyl species of transition metals and electromagnetic charge, which could exist in the impact-induced high-velocity jet of vapor and melts.PostprintPeer reviewe

Redox-mediated C–C bond scission in alcohols adsorbed on CeO2−x thin films

AbstractThe decomposition mechanisms of ethanol and ethylene glycol on well-ordered stoichiometric CeO2(111) and partially reduced CeO2−x (111) films were investigated by means of synchrotron radiation photoelectron spectroscopy, resonant photoemission spectroscopy, and temperature programmed desorption. Both alcohols partially deprotonate upon adsorption at 150 K and subsequent annealing yielding stable ethoxy and ethylenedioxy species. The C–C bond scission in both ethoxy and ethylenedioxy species on stoichiometric CeO2(111) involves formation of acetaldehyde-like intermediates and yields CO and CO2 accompanied by desorption of acetaldehyde, H2O, and H2. This decomposition pathway leads to the formation of oxygen vacancies. In the presence of oxygen vacancies, C–O bond scission in ethoxy species yields C2H4. In contrast, C–C bond scission in ethylenedioxy species on the partially reduced CeO2−x (111) is favored with respect to C–O bond scission and yields methanol, formaldehyde, and CO accompanied by the desorption of H2O and H2. Still, scission of C–O bonds on both sides of the ethylenedioxy species yields minor amounts of accompanying C2H4 and C2H2. C–O bond scission is coupled with a partial recovery of the lattice oxygen in competition with its removal in the form of water

Hydrogen activation on Pt–Sn nanoalloys supported on mixed Sn–Ce oxide films

We have studied the interaction of H2 with Pt–Sn nanoalloys supported on Sn–Ce mixed oxide films of different composition by means of synchrotron radiation photoelectron spectroscopy and resonant photoemission spectroscopy. The model catalysts are prepared in a three step procedure that involves (i) the preparation of well-ordered CeO2(111) films on Cu(111) followed by subsequent physical vapor deposition of (ii) metallic Sn and (iii) metallic Pt. The formation of mixed Sn–Ce oxide is accompanied by partial reduction of Ce4+ cations to Ce3+. Pt deposition leads to the formation of Pt–Sn nanoalloys accompanied by the partial re-oxidation of Ce3+ to Ce4+. Subsequent annealing promotes further Pt–Sn alloy formation at expense of the Sn content in the Sn–Ce mixed oxide. Adsorption of H2 on Pt–Sn/Sn–Ce–O at 150 K followed by stepwise annealing results in reversible reduction of Ce cations caused by spillover of dissociated hydrogen between 150 and 300 K. Above 500 K, annealing of Pt–Sn/Sn–Ce–O in a hydrogen atmosphere results in irreversible reduction of Ce cations. This reduction is caused by the reaction of hydrogen with oxygen provided by the mixed oxide substrate via the reverse spillover to Pt–Sn nanoalloy. The extent of the hydrogen and oxygen spillover strongly depends on the amount of Sn in the Sn–Ce mixed-oxide. We observe an enhancement of hydrogen spillover on Pt–Sn/Sn–Ce–O at low Sn concentration as compared to Sn-free Pt/CeO2. Although the extent of hydrogen spillover on Pt–Sn/Sn–Ce–O with high Sn concentration is comparable to Pt/CeO2, the reverse oxygen spillover is substantially suppressed on these samples

Surface sites on Pt–CeO2 mixed oxide catalysts probed by CO adsorption: a synchrotron radiation photoelectron spectroscopy study

By means of synchrotron radiation photoemission spectroscopy, we have investigated Pt–CeO2 mixed oxide films prepared on CeO2(111)/Cu(111). Using CO molecules as a probe, we associate the corresponding surface species with specific surface sites. This allows us to identify the changes in the composition and morphology of Pt–CeO2 mixed oxide films caused by annealing in an ultrahigh vacuum. Specifically, two peaks in C 1s spectra at 289.4 and 291.2 eV, associated with tridentate and bidentate carbonate species, are formed on the nanostructured stoichiometric CeO2 film. The peak at 290.5–291.0 eV in the C 1s spectra indicates the onset of restructuring, i.e. coarsening, of the Pt–CeO2 film. This peak is associated with a carbonate species formed near an oxygen vacancy. The onset of cerium oxide reduction is indicated by the peak at 287.8–288.0 eV associated with carbonite species formed near Ce3+ cations. The development of surface species on the Pt–CeO2 mixed oxides suggests that restructuring of the films occurs above 300 K irrespective of Pt loadings. We do not find any adsorbed CO species associated with Pt4+ or Pt2+. The onset of Pt2+ reduction is indicated by the peak at 286.9 eV in the C 1s spectra due to CO adsorption on metallic Pt particles. The thermal stability of Pt2+ in Pt–CeO2 mixed oxide depends on Pt loading. We find excellent stability of Pt2+ for 12% Pt content in the CeO2 film, whereas at a Pt concentration of 25% in the CeO2 film, a large fraction of the Pt2+ is converted into metallic Pt particles above 300 K

Excitons at the B K edge of boron nitride nanotubes probed by x-ray absorption spectroscopy

We have performed a near-edge x-ray absorption fine-structure (NEXAFS) investigation of multi-walled boron nitride nanotubes (BNNTs). We show that the one-dimensionality of BNNTs is clearly evident in the B K edge spectrum, while the N K edge spectrum is similar to that of layered hexagonal BN (h-BN). We observe a sharp feature at the Ã* onset of the B K edge, which we ascribe to a core exciton state. We also report a comparison with spectra taken after an ammonia plasma treatment, showing that the B K edge becomes indistinguishable from that of h-BN, due to the breaking of the tubular order and the formation of small h-BN clusters

Reactivity of atomically dispersed Pt2+ species towards H2: model Pt–CeO2 fuel cell catalyst

The reactivity of atomically dispersed Pt2+ species on the surface of nanostructured CeO2 films and the mechanism of H2 activation on these sites have been investigated by means of synchrotron radiation photoelectron spectroscopy and resonant photoemission spectroscopy in combination with density functional calculations. Isolated Pt2+ sites are found to be inactive towards H2 dissociation due to high activation energy required for H–H bond scission. Trace amounts of metallic Pt are necessary to initiate H2 dissociation on Pt–CeO2 films. H2 dissociation triggers the reduction of Ce4+ cations which, in turn, is coupled with the reduction of Pt2+ species. The mechanism of Pt2+ reduction involves reverse oxygen spillover and formation of oxygen vacancies on Pt–CeO2 films. Our calculations suggest the existence of a threshold concentration of oxygen vacancies associated with the onset of Pt2+ reduction

Phosphorus poisoning during wet oxidation of methane over Pd@CeO2/graphite model catalysts

10siThe influence of phosphorus and water on methane catalytic combustion was studied over Pd@CeO2 model catalysts supported on graphite, designed to be suitable for X-ray Photoelectron Spectroscopy/Synchrotron Radiation Photoelectron Spectroscopy (XPS/SRPES) analysis. In the absence of P, the catalyst was active for the methane oxidation reaction, although introduction of 15% H2O to the reaction mixture did cause reversible deactivation. In the presence of P, both thermal and chemical aging treatments resulted in partial loss of activity due to morphological transformation of the catalyst, as revealed by Scanning Electron Microscopy (SEM) and Atomic Force Microscopy (AFM) analysis. At 600 °C the combined presence of PO43− and water vapor caused a rapid, irreversible deactivation of the catalyst. XPS/SRPES analysis, combined with operando X-ray Absorption Near Edge Structure (XANES) and AFM measurements, indicated that water induces severe aggregation of CeO2 nanoparticles, exposure of CePO4 on the outer layer of the aggregates and incorporation of the catalytic-active Pd nanoparticles into the bulk. This demonstrates a temperature-activated process for P-poisoning of oxidation catalysts in which water vapor plays a crucial role.partially_openembargoed_20171009Monai, Matteo; Montini, Tiziano; Melchionna, Michele; Duchoň, Tomáš; Kúš, Peter; Tsud, Nataliya; Prince, Kevin C.; Matolin, Vladimir; Gorte, Raymond J.; Fornasiero, PaoloMonai, Matteo; Montini, Tiziano; Melchionna, Michele; Duchoň, Tomáš; Kúš, Peter; Tsud, Nataliya; Prince, Kevin C.; Matolin, Vladimir; Gorte, Raymond J.; Fornasiero, Paol