Legfontosabb kutatasi eredmenyeink: az eolikus uledekek es felszinek elterjedesenek es koranak meghatarozasa, megayardangok es plato helyzetű eolikus kepződmenyek leirasa, valamint a deflacio meghatarozo szerepenek kimutatasa a Dunantul mai domborzatanak, igy a zalai es somogyi un. meridionalis volgyrendszer kialakitasaban is. A szelmarta kőzetfelszinek kozmogen 10Be izotopos korat a melysegprofilok menti mintavetelezesi modszer alkalmazasaval sikerult meghataroznunk. Ezt a modszert korabban szelcsiszolta kőzetfelszineken meg nem alkalmaztak; elsőkent sikerult 1,5 millio eves szelcsiszolta sziklafelszint datalnunk Europaban. A Tapolcai- es Kali-medencek negyedidőszaki deflacios alacsonyodasi rataja 40-75 m/My volt, ugyanakkor a kipreparalodo kvarcittombok csupan 2-4 m-t pusztulnak evmillionkent. A kulonboző koru szelmarta felszineken mert szelkarc iranyok megfeleltek a mai ENy-ias szeliranynak. Ezzel igazoltuk az allandonak tekinthető uralkodo szeliranyt a negyedidőszak soran. Az OSL kormeghatarozassal 8-80 ezer eves uledekeket sikerult datalnunk a Vertes kornyezeteben. Az uledekanyag szemcseit a betemetődes előtt nem erte elegendő feny ahhoz, hogy a lumineszcens szignal teljesen lenullazodjon. Ezt valoszinűleg a rovid szallitasi tavolsag okozhatta. Ezzel magyarazhato, hogy a vizsgalt uledekek eseteben a geomorfologia es a korabbi koradatok tukreben tobbnyire a centralis OSL kor adja meg a betemetődes korat. | Our most important results are: determination of the distribution and age of aeolian landforms and sediments and description of megayardangs and aeolian formations in plateau position. We demonstrated that deflation played a definitive role in the formation of the topography of Transdanubia and in the development of the radial valley system of Zala and Somogy countries. Age and denudation rate of the wind-abraded rock surfaces was determined using in situ produced 10Be depth profiles. This was the first application of this method on wind-polished rock surfaces, and the first time when a 1.5 million years old wind-abraded surface was dated in Europe. Quaternary deflational surface lowering of the Tapolca and Kal Basins was 40-75 m/My, while denudation rate of the cemented quartzite rock surfaces was only 2-4 m/My. We proved long term stability of north-westerly winds by the measurement of the direction of wind striations rock surfaces of different age. OSL ages of aeolian sediments in the Vertes foreland were 8-80 ky old. The sediments were not exposed to sunlight for enough time to anneal completely the luminescence signal, most probably because of the short distance of transportation. This is the reason why the central OSL ages provide the age of sedimentation, considering the geomorphology and previous age data as well.
A procedure is developed for defining a compositionally and structurally realistic, atomic-scale description of exfoliated clay nanoparticles from the kaolinite family of phylloaluminosilicates. By use of coordination chemical principles, chemical environments within a nanoparticle can be separated into inner, outer, and peripheral spheres. The edges of the molecular models of nanoparticles were protonated in a validated manner to achieve charge neutrality. Structural optimizations using semiempirical methods (NDDO Hamiltonians and DFTB formalism) and ab initio density functionals with a saturated basis set revealed previously overlooked molecular origins of morphological changes as a result of exfoliation. While the use of semiempirical methods is desirable for the treatment of nanoparticles composed of tens of thousands of atoms, the structural accuracy is rather modest in comparison to DFT methods. We report a comparative survey of our infrared data for untreated crystalline and various exfoliated states of kaolinite and halloysite. Given the limited availability of experimental techniques for providing direct structural information about nano-kaolinite, the vibrational spectra can be considered as an essential tool for validating structural models. The comparison of experimental and calculated stretching and bending frequencies further justified the use of the preferred level of theory. Overall, an optimal molecular model of the defect-free, ideal nano-kaolinite can be composed with respect to stationary structure and curvature of the potential energy surface using the PW91/SVP level of theory with empirical dispersion correction (PW91+D) and polarizable continuum solvation model (PCM) without the need for a scaled quantum chemical force field. This validated theoretical approach is essential in order to follow the formation of exfoliated clays and their surface reactivity that is experimentally unattainable.
Raman spectra of the hydroxyl-stretching region of potassium acetate-intercalated kaolinite were obtained under an atmosphere of both air and nitrogen using a thermal stage over the temperature range 25-300 °C. At 25 °C, an additional band at 3606 cm-1 attributed to the inner surface hydroxyl hydrogen bonded to the acetate ion is observed with a concomitant loss of intensity in the bands attributed to the inner surface hydroxyls. Heating the intercalated complex to 50 °C results in two hydroxyl-stretching wavenumbers at 3594 and 3604 cm-1. At 100 °C, the bands shift to 3600 and 3613 cm-1. At temperatures from 100 to 300 °C, bands are observed in similar positions. Upon cooling in air to 25 °C, the acetate-bonded inner surface hydroxyl stretching wavenumber shifts back to 3606 cm-1. Upon heating the intercalated kaolinite to 300 °C under an atmosphere of nitrogen and upon cooling the acetate-bonded inner surface hydroxyl stretching wavenumber is observed at 3601 cm-1. Upon cooling to 150 °C and subsequently to 25 °C, two bands are observed at 3611 and 3600 cm-1. Upon rehydration, the hydroxyl stretching wavenumber returns to 3606 cm-1. The changes in the Raman spectra of the hydroxyl-stretching region during dehydration and rehydration are reversible. When the potassium acetate-intercalated kaolinite is heated to 300 °C and cooled to 25 °C, the inner-hydroxyl band is observed at 3630 cm-1. The shift in the wavenumber of the inner hydroxyl band is attributed to the insertion of the potassium ion in the ditrigonal cavity of the siloxane layer.
The Sylow p-subgroups of the symmetric group S_p^n satisfy the appropriate generalization of Maschke's Theorem to the case of a p'-group acting on a (not necessarily abelian) p-group. Moreover, some known results about the Sylow p-subgroups of S_p^n are stated in a form that is true for all primes p.
'/%3e%3c/defs%3e%3cpath fill='%23012169' d='M0 0h10080v5040H0z'/%3e%3cpath stroke='%23fff' stroke-width='.6' d='m0 0 6 3m0-3L0 3' clip-path='url(%23b)' transform='scale(840)'/%3e%3cpath stroke='%23e4002b' stroke-width='.4' d='m0 0 6 3m0-3L0 3' clip-path='url(%23c)' transform='scale(840)'/%3e%3cpath stroke='%23fff' stroke-width='840' d='M2520 0v2520M0 1260h5040'/%3e%3cpath stroke='%23e4002b' stroke-width='504' d='M2520 0v2520M0 1260h5040'/%3e%3cg fill='%23fff'%3e%3cuse xlink:href='%23d' x='2520' y='3780'/%3e%3cuse xlink:href='%23a' x='7560' y='4200'/%3e%3cuse xlink:href='%23a' x='6300' y='2205'/%3e%3cuse xlink:href='%23a' x='7560' y='840'/%3e%3cuse xlink:href='%23a' x='8680' y='1869'/%3e%3cuse xlink:href='%23e' x='8064' y='2730'/%3e%3c/g%3e%3c/svg%3e)