Mátrixizolációs infravörös spektroszkópiai vizsgálatok = Matrix isolation infrared spectroscopic investigations

Kutatási eredményeinket két fő csoportra lehet osztani. Az eredmények egyik részét légkörkémiai vagy asztrokémiai szempontból érdekes gyökök valamint reaktív, egzotikus molekulák előállítása és spektroszkópia vizsgálata adja. Alkil-nitritek fotolízise során sikerült kimutatni az alkoxigyököt, mint köztiterméket, amerikai-magyar együttműködésben pedig alkil-peroxigyökök spektrumát analizáltuk. Ezek az eredmények segítséget nyújthatnak e specieszek légköri monitorálásához, illetve további kinetikai mérésekhez. Elsőként előállítottuk az asztrofizikusok és a preparatív kémikusok számára is érdekes tiofulminsavat (HCNS), illetve ennek származékait, pl. az FCNS-t. Ez az első olyan vizsgálat, amelyben egy nitril-szulfid N-S nyújtási rezgését sikerült kimérni. Eredményeink másik csoportjába modellpeptidek mátrixizolációs konformációanalízise sorolható. Mátrixizolációs infravörös (MI-IR) és az általunk elsők között alkalmazott mátrixizolációs rezgési circuláris dikroizmus (MI-VCD) spektroszkópiával alfa- és beta-peptidekmodellek, illetve ezek vízzel alkotott komplexeit vizsgáltuk. Többek között megmutattuk, hogy bár a beta-peptidek flexibilisebbek, mint a megfelelő alfa-peptidek, az erős hidrogénkötés miatt mégis csak egy domináns konformerük van. Megmutattuk, hogy a vízzel való komplexálás jelentős konformációváltozást eredményez, valamint kimutattuk a vizes a komplexekben az ún. kiralitás transzfer jelenségét. | Our results can be divided into two parts. Results on atmospherically or astrophysically relevant species belong to one group. Among these, alkoxy radicals have been identified as intermediates in matrix photolysis of alkyl-nitrites. Furthermore, the spectra of alkyl-peroxy radicals have been analyzed in US-Hungarian cooperation. These results can help the atmospheric monitoring of these species, and further kinetic measurements. Thiofulminic acid (HCNS), relevant both for astrophysicists and preparative chemists, has been prepared for the first time, together with its derivatives, e.g. FCNS. This is also the first measurement on the N-S stretching mode of a nitrile sulfide. Conformational analysis of model peptides constitutes the other group of our results. Conformational distribution of alfa- and beta-peptides have been analyzed by the aid of matrix isolation infrared (MI-IR) and matrix isolation vibrational dichroism (MI-VCD) spectroscopy. The latter has been developed and used by our group among the firsts. Besides many other results, it has been shown that although beta-peptides are more flexible than their alfa analogues, due to the strong H-bond their conformers are less evenly distributed. It has also been showed that complexation with water induces significant conformational change. The so-called chirality transfer phenomena has also been demonstrated in the water-peptide complexes

Study of distributed occupant-seat interactions as an objective measure of seating comfort

The automotive interior is characterized as a confined workspace into which the occupants are required to adapt in order to perform the normal driving and vehicular control tasks. As part of the interface between the driver and the automobile, the automotive seat must provide the occupant with a comfortable environment in which driving can be performed in a safe and comfortable manner. Prolonged exposure to excessive loading on the body in the seated position is related to discomfort and pain. Seating comfort has been found to be a complex function of the occupant anthropometry, the seated posture and many seat design factors. The characterization of the interactions between the occupant and the seat under various conditions thus constitutes an important goal for enhancing the knowledge of essential design factors that could yield improved seating comfort. The occupant-seat interactions are investigated through measurement and analysis of the generalized and distributed contact forces and pressures at the body-seat-pan and body-backrest interfaces of a total of three different automotive seats. The contact force, contact area, and peak and mean pressure responses are analyzed as a function of the occupant anthropometry, the seated posture and the seat design features. Single and multi-factor statistical analyses are performed for the response data to identify the significance of the experimental factors considered in this stud

MAPPING THE CONFORMATION SPACE OF α-PROLINE BY MATRIX-ISOLATION IR SPECTROSCOPY COMBINED WITH NIR LASER INDUCED CONFORMATIONAL CHANGE AND STATE-OF-THE-ART AB INITIO COMPUTATIONS

The conformers of $\alpha$-proline were studied by matrix-isolation IR spectroscopy. In order to group the vibrational bands to different conformers, conformational changes were induced by NIR laser irradiations, by exciting the OH stretching overtone of a selected conformer. For identification, the single conformer spectra were compared to state-of-the-art ab initio computations. Infrared spectra and anharmonic thermodynamic corrections have been computed by means of second order vibrational perturbation theory (VPT2), with GVPT2 and HDCPT2 models, respectively. A hybrid force-field was developed by addition of the cubic and semi-diagonal quartic B3LYP-D3/SNSD force constants to the (harmonic quadratic) B2PLYP-D3/maug-cc-pVTZ results. As the result of the spectrum analysis, seven conformers could be identified. Four of these conformers were present in the as-deposited matrix, two of them were generated by the NIR laser irradiation, and found to be stable in Ar matrix. The seventh conformer could also be produced upon the NIR laser irradiation, and it decays by H-atom tunneling to a lower energy form on the sub-second and minute timescales in Ar and N$_{2}$ matrices, respectively

Tunneling Lifetime of the ttc/VIp Conformer of Glycine in Low-Temperature Matrices

Conformer ttc/VIp of glycine and glycine-N,N,O-d(3) has been prepared in low-temperature Ar, Kr, Xe, and N-2 matrices by near-infrared (NIR) laser irradiation of the first OH stretching overtone of conformer ttt/Ip. Glycine (and glycine-N,N,O-d(3)) ttc/VIp was found to convert back to ttt/Ip in the dark by hydrogen-atom tunneling. The observed half-lives of ttc/VIp in Ar, Kr, and Xe matrices at 12 K were 4.4 +/- 1 s (50.0 +/- 1 h), 4.0 +/- 1 s (48.0 +/- 1 h), and 2.8 +/- 1 s (99.3 +/- 2 h), respectively. In correspondence with the observation for the cis-to-trans conversion of formic and acetic acid, the tunneling half-life of glycine ttc/VIp in a N-2 matrix is more than 3 orders of magnitude longer (6.69 X 10(3) and 1.33 X 10(4) s for two different sites) than in noble gas matrices due to complex formation with the host molecules. The present results are important to understand the lack of experimental observation of some computationally predicted conformers of glycine and other amino acids

A bioszféra szerepe a légkör szén-dioxid tartalmának alakulásában = The role of the biosphere in the carbon dioxide budget of the atmosphere

A kutatási munkatervnek megfelelően a teljes kutatási időszakban folyamatosan mértük a hegyhátsáli mérőállomáson a CO2 koncentráció függőleges koncentráció-profilját és a régiót reprezentáló felszín-légkör szén-dioxid áramot. A mérőrendszert 2005 végén a mérőállomás közelében lévő kvázi-természetes gyep szén-dioxid forgalmának folyamatos mérésére alkalmas műszeregyüttessel egészítettük ki. 2006 elejétől folyamatosan mérjük a levegő metán, dinitrogén-oxid, kén-hexafluorid és szén-monoxid koncentrációját. Holland és amerikai együttműködésben eseti mintavétel alapján mértük a légköri szén-dioxid stabilizotóp-összetételét, és Európai Uniós támogatással a szén-dioxid függőleges koncentráció-profil méréseket nagy gyakoriságú (évi 80) repülőgépes mintavételekkel 3000 m-ig terjesztettük ki. Az adatok hozzáférhetők a nemzetközi kutatási programok számára. Megvizsgáltuk a koncentráció és a függőlege CO2-áram mérések területi reprezentativitását. Egyszerű box-modellt dolgoztunk ki a határrétegbeli koncentrációk időbeli menetének leírására, felhasználva a függőleges anyagáram méréseket, illetve a stabilizotóp-mérések eredményeit. A felszín és a légkör közötti szén-dioxid csere leírására adaptáltuk a Biome-BGC folyamatorientált ökológiai rendszer modellt, melynek segítségével megtettük az első kísérletet az országos léptékű bioszférikus CO2 mérleg meghatározására. Feldolgoztuk és kiértékeltük a hazai munkával, illetve amerikai kooperációban végzett nem-CO2 üvegházgáz méréseket. | In accordance with the workplan the vertical concentration profile of CO2 and the regional scale surface-atmosphere CO2 flux were continuously measured at Hegyhátsál. At the end of 2005 the monitoring system was completed by instrumentations measuring the surface-atmosphere CO2 budget of a semi-natural grassland located nearby to the station. Since the beginning of 2006 mixing ratios of methane, nitrous oxide, sulfur hexafluoride and carbon monoxide have also been monitored. In cooperation with American and Dutch partners the stable isotope composition of CO2 was also measured from occasionally taken air samples. The European Union supported the extension of the CO2 vertical concentration profiles up to 3000 m by means of frequent (80/year) aircraft soundings. The data are publicly available for the international research programs. The spatial representativeness of both the concentration measurements and the vertical flux measurements was studied. A simple box model was developed for the simulation of the temporal variation in the concentration of atmospheric trace constituents using the vertical flux and stable isotope concentration measurements. For the description of the surface-atmosphere CO2 exchange a process based ecological modell (Biome-BGC) was adapted. Using the model the first attempt was done to determine the biospheric carbon dioxide budget of Hungary. The available non-CO2 data were evaluated

Planetary nurseries: vortices formed at smooth viscosity transition

Excitation of Rossby wave instability and development of a large-scale vortex at the outer dead zone edge of protoplanetary discs is one of the leading theories that explains horseshoe-like brightness distribution in transition discs. Formation of such vortices requires a relatively sharp viscosity transition. Detailed modelling, however, indicates that viscosity transitions at the outer edge of the dead zone is relatively smooth. In this study, we present 2D global, non-isothermal, gas-dust coupled hydrodynamic simulations to investigate the possibility of vortex excitation at smooth viscosity transitions. Our models are based on a recently postulated scenario, wherein the recombination of charged particles on the surface of dust grains results in reduced ionisation fraction and in turn the turbulence due to magnetorotational instability. Thus, the alpha-parameter for the disc viscosity depends on the local dust-to-gas mass ratio. We found that the smooth viscosity transitions at the outer edge of the dead zone can become Rossby unstable and form vortices. A single large-scale vortex develops if the dust content of the disc is well coupled to the gas, however, multiple small-scale vortices ensue for the case of less coupled dust. As both type of vortices are trapped at the dead zone outer edge, they provide sufficient time for dust growth. The solid content collected by the vortices can exceed several hundred Earth masses, while the dust-to-gas density ratio within often exceeds unity. Thus, such vortices function as planetary nurseries within the disc, providing ideal sites for formation of planetesimals and eventually planetary systems.Comment: accepted for publication in MNRA

DEAFBLINDNESS – A COMBINED IMPAIRMENT

U Europi i svijetu gluhosljepoća je prepoznata i priznata kao jedinstveno oštećenje, a gluhoslijepe osobe imaju i ostvaruju razna zakonska prava i povlastice. Nedostatno znanje i razumijevanje gluhosljepoće, u Republici Hrvatskoj još uvijek predstavlja probleme s kojima se suočavaju stručnjaci raznih profila u identifikaciji, dijagnosticiranju i klasifikaciji gluhoslijepih osoba. U članku se poseban naglasak daje razvoju terminoloških odrednica s područja gluhosljepoće, teoretskom prikazu definicije i klasifikacije gluhosljepoće s ciljem prevladavanja dosadašnjih ukorijenjenih predrasuda i nedoumica vezanih uz gluhosljepoću.In Europe and in the world, deafblindness is recognised as a combined impairment, and deafblind persons have and realise certain legal rights and benefits. Insufficient knowledge and understanding of deafblindness in the Republic of Croatia still presents a problem that the professionals of different profiles are faced with in the identification, diagnosing and classification of deafblind persons. The paper emphasises the development of terminological guidelines from the area of deafblindness, the theoretical survey of the definition and classification of deafblindness with the purpose of overcoming the current deep-rooted prejudice and dilemmas related to deafblindness

VIZSLA -- Versatile Ice Zigzag Sublimation Setup for Laboratory Astrochemistry

In this article a new, multi-functional, high-vacuum astrophysical ice setup, VIZSLA (Versatile Ice Zigzag Sublimation Setup for Laboratory Astrochemistry), is introduced. The instrument allows the investigation of astrophysical processes both in a low-temperature para-H2 matrix and in astrophysical analog ices. In para-H2 matrix the reaction of astrochemical molecules with H atoms and H+ ions can be studied very effectively. For the investigation of astrophysical analog ices the setup is equipped with different irradiation and particle sources: an electron gun, for modeling cosmic rays; an H atom beam source (HABS); a microwave H atom lamp, for generating H Lyman-alpha radiation, and a tunable (213 nm to 2800 nm) laser source. For analysis, an FT-IR (and a UV-Visible) spectrometer and a quadrupole mass analyzer are available. The setup has two cryostats, offering novel features for analysis. Upon the so-called temperature-programmed desorption (TPD) the molecules, desorbing from the first cryostat, can be mixed with Ar and can be deposited onto the substrate of the other cryostat. The well-resolved spectrum of the molecules isolated in an Ar matrix serves a unique opportunity to identify the desorbing products of a processed ice. Some examples are provided to show how the para-H2 matrix experiments and the TPD -- matrix-isolation recondensation experiments can help to understand astrophysically important chemical processes at a low temperature. It is also discussed, how these experiments can complement the studies carried out by similar astrophysical ice setups.Comment: 37 pages, 14 figures, 1tabl

Testing Ultra-low Amplitude Cepheid Candidates in the Galactic Disk by TESS and Gaia

Ultra-low amplitude (ULA) and strange mode Cepheids are thought to be pulsating variable stars that are near to or are at the edges of the classical instability strip. Until now, a few dozen such variable star candidates have been found both in the Large Magellanic Cloud and the Milky Way. In this present work, we studied six ULA Cepheid candidates in the Milky Way, identified by Szab\'o et al. (2009) using CoRoT and 2MASS data. In order to identify their positions in the period--luminosity and color--magnitude diagrams, we used the Gaia DR3 parallax and brightness data of each star to calculate their reddening-free absolute magnitudes and distances. Furthermore, we calculated the Fourier parameters (e.g., period and amplitude) of the light variations based on CoRoT and TESS measurements, and established the long-term phase shifts for four out of six stars. Based on the results, we conclude that none of the six ULA Cepheid candidates are pulsating variable stars, but rather rotation-induced variable stars (rotational spotted and $\alpha^2$~Canum Venaticorum variables) that are either bluer or fainter than Cepheids would be.Comment: 14 pages, 6 tables, 10 figures. Accepted to Astronomy and Astrophysic