90 research outputs found
Vitéz Perczel József könyve
No full textJ. K.http://www.lib.unideb.huDebreceni Egyetem Egyetemi és Nemzeti KönyvtárBőrkötéses kapcsos könyv, fedelén a család címerével. Címer: sisakdíszen egy ágaskodó oroszlán, a pajzs része négyosztatú. Alul felirat: Vitéz Perczel József könyve. A kép hátulján: Fecit Kollmann Jenő felirat.metsze
GIAO-PCM Calculations on Alanine Diamide Models Aimed at Predicting Protein Secondary Structures
No full textIn this paper we extend our theoretical studies dealing with the dependence of
relative proton and carbon chemical shifts (CSs) of protein backbone atoms on their
conformational position. In an earlier paper (A. Czajlik, I. Hudáky, A. Perczel, J Comp
Chem 2011, 32, 3362) we reported on a fair agreement between calculated and
observed backbone CSs as a function of backbone conformation. Applying the
polarizable continuum model (PCM) in this work, we compare relative CSs of fully
optimized alanine diamide conformers with gas phase calculations and experimental
results. Along a path on the Ramachandran surface, we collated calculated relative
CSs obtained with and without explicit water molecules, as well as with and without
considering the PCM reaction field. Furthermore, we traced the energetically relevant
reaction paths along the torsional angle ψ connecting the lowest energy minima
(helical, extended, polyproline II and inverse γ-turn) on the Ramachandran plot, with
the prospect to facilitate identifying them by their relative CSs. We found that
consideration of the solvent effect of the environment around a diamide model
improves the agreement with experimental findings on abundant conformers. This
agreement is of the level achieved previously by a thorough gas phase investigation
on considerably larger oligoalanine models. By relating DeltaδCα, DeltaδHα and DeltaδCβ values
of polyproline II and inverse γ-turn to the experimentally well characterized helical
and extended data, our calculations contribute to protein secondary structure
prediction based on nuclear magnetic CS
Photonic band structure of two-dimensional atomic lattices
No full textTwo-dimensional atomic arrays exhibit a number of intriguing quantum optical phenomena, including subradiance, nearly perfect reflection of radiation, and long-lived topological edge states. Studies of emission and scattering of photons in such lattices require complete treatment of the radiation pattern from individual atoms, including long-range interactions. We describe a systematic approach to perform the calculations of collective energy shifts and decay rates in the presence of such long-range interactions for arbitrary two-dimensional atomic lattices. As applications of our method, we investigate the topological properties of atomic lattices both in free space and near plasmonic surfaces
Analysis of hydrogen bonds in peptides, based on the hydration affinity of amides
No full textThe difference in the affinity for water of peptide groups embedded in different molecular environments was investigated. The chemical shift of an amide proton is sensitive to conformational variations, as well as to changes in the molecular environment [D.S. Wishat, B.D. Sykes and F.M. Richards, J. Mol. Biol., 222 (1991) 311\u2013333]. Therefore, if the conformational motions are minimized or excluded, the observed changes in the chemical shift can simply be related to the environmental effects. The conformation(s) of the cyclic \u3b2-turn models studied in this work has been previously reported using X-ray, NMR, circular dichroism, and (FT-IR) spectroscopic methods, as well as MD calculations. [M. Holl\uf3si, K.E. K\uf6ver, S. Holly, L. Radics and G.D. Fasman, Biopolymers, 26 (1987) 1527\u20131572; A. Perczel, M. Holl\uf3si, B.M. Foxman and G.D. Fasman, J. Am. Chem. Soc., 113 (1991) 9772\u20139784; and H.H. Mantsch, A. Perczel, M. Holl\uf3si and G.D. Fasman, Biopolymers, 33 (1993) 201\u2013207]. The backbone of the cyclo[(\u3b4)Ava\u2014Gly\u2014Pro\u2014Aaa\u2014Gly] (where Aaa = Ser(OtBu), Ser or Thr(OtBu), and \u3b4(Ava) is \u3b4-aminovaleric acid) compounds was found to be rigidly incorporated in the structure and to contain two intramolecular hydrogen bonds. These \u3b2-turn models also include one (or two) \u201cfree\u201d amide group(s) that are not involved in any type of interaction. The \u201cwater titration\u201d of these amide groups in acetonitrile, where they are involved in various degrees of hydrogen bonding, revealed their molecular environment. Owing to the rigidity of these structures, the observed changes in the amide proton chemical shifts, during titration were attributed to their involvement in hydrogen bonding. This was confirmed by monitoring the water titration simultaneously with FT-IR spectroscopy. The phenomenon described here, with the proposed characterization of the investigated peptide/water system, comprise an improvement in the NMR method for analyzing the hydrogen bonding of small rigid peptides.Peer reviewed: YesNRC publication: Ye
Topological Quantum Optics in Two-Dimensional Atomic Arrays
No full textWe demonstrate that two-dimensional atomic emitter arrays with subwavelength spacing constitute topologically protected quantum optical systems where the photon propagation is robust against large imperfections while losses associated with free space emission are strongly suppressed. Breaking time-reversal symmetry with a magnetic field results in gapped photonic bands with nontrivial Chern numbers and topologically protected, long-lived edge states. Due to the inherent nonlinearity of constituent emitters, such systems provide a platform for exploring quantum optical analogs of interacting topological systems.National Science Foundation (U.S.)MIT-Harvard Center for Ultracold AtomsUnited States. Air Force. Office of Scientific ResearchUnited States. Multidisciplinary University Research InitiativeHungary Initiatives Foundatio
Peptide models XXV. Side-chain conformational potential energy surface, E = E(χ1, χ2) of N-formyl-L-aspartic acidamide and its conjugate base N- formyl-L-aspartatamide in their γ(L) backbone conformations
No full textAb initio molecular computations were carried out on the γ(L) backbone conformation of N-formyl-L-aspartic acidamide and its conjugate base N- formyl-L-aspartatamide at the HF/3-21G level of theory. All side-chain conformations were explored for the parent amino acid diamide and its conjugate base. Propionate ion, propionic acid, 3,3-difluoropropionate ion and 3,3-difluoropropionic acid were used to model the side-chain in the anionic and neutral compounds.Fil: Salpietro, Salvatore J.. University of Toronto; CanadáFil: Perczel, Andràs. University of Oxford; Reino Unido. Eötvös Loránd Tudományegyetem; HungríaFil: Farkas, Od̈ön. Eötvös Loránd Tudományegyetem; Hungría. Wayne State University; Estados UnidosFil: Enriz, Ricardo Daniel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - San Luis. Instituto Multidisciplinario de Investigaciones Biológicas de San Luis. Universidad Nacional de San Luis. Facultad de Ciencias Físico Matemáticas y Naturales. Instituto Multidisciplinario de Investigaciones Biológicas de San Luis; Argentina. Universidad Nacional de San Luis. Facultad de Química, Bioquímica y Farmacia. Departamento de Química; ArgentinaFil: Csizmadia, Imre Gyula. University of Toronto; Canad
Elekes Ferenc és glóbuszai: Egy hazánkban eddig ismeretlen Elekes-földgömb Bécsben | Ferenc Elekes and his globes – Elekes’s globe in Vienna unknown in Hungary
No full textA 19. század neves magyar (vagy magyar származásúnak
vélhető) glóbuszkészítői sorát Elekes Ferenc,
Lettány Ferenc, Nagy Károly, Perczel László,
Gönczy Pál, Hunfalvy János és Kogutovicz
Manó neve fémjelzi. A nevezett glóbuszkészítők
és munkáik közül szakfolyóiratunk hasábjain
az ez évi 3. számban már megismerkedhettünk
Perczel Lászlóval és 132 cm átmérőjű csodálatos
kéziratos földgömbjével. Jelen dolgozat Perczel
egyik 19. századi szakmai elődjével, Elekes
Ferenccel és munkáival foglalkozik.
|
The major Hungarian globe makers – including
those who may be considered Hungarian after
their origin – in the 19th century were Ferenc
Elekes, Ferenc Lettány, Károly Nagy, László
Perczel, Pál Gönczy, János Hunfalvy and Manó
Kogutowicz. This paper deals with Ferenc Elekes
and his work.
All Hungarian sources only mention Elekes’s
globe from 1831. None of them published a picture of
the globe and did not know about its occurrence in a
Hungarian collection. The author has recently found
two globes of Elekes in Vienna with the help of Eszter
Dombóvári, a PhD student of the Department of
Cartography and Geoinformatics at Eötvös Loránd
University. With the kind permission of Mag. Gerhard
Holzer, head of the Woldan Collection of the
Austrian Academy of Sciences, and dr. Heinz Ristory,
Director of Stiftsbibliothek Klosterneuburg,
Mátyás Gede and Gábor Gercsák from the Department
took colour photographs of the globes.
Now we know not only the 12 cm globe of
Elekes from 1831, but also another one of 16.5 cm
from 1844, and we have detailed images of the
content of both products
Sicherer Wegweiser für die bioethischen Labyrinthe von Psychiatrie und Psychotherapie
No full textRecenzió az alábbi műről:
KOVÁCS, J. (2007) Bioetikai kérdések a pszichiátriában és a pszichoterápiában (Budapest: Medicina) 677 S., 24 cm, ISBN-97 89632260884, HUF 6.400
Where is toxicity located? Side glances through fieldwork in a toxic place
No full textDespite the notorious invisibility of toxicity, an aesthetic narrative has developed around the threat of e-waste. In reports about toxicity in New Delhi, India, the dirt, grime and discarded remnants of electronics are presented in a particular visual manner to instil horror among readers and viewers. Such a representation has far-reaching influences on policy. The seven pictures and the accompanying text in this article seek to challenge such a linear narrative of e-waste's toxicity and offer fragments of other untold stories that challenge the established narrative and evoke the rich social life entwined with e-waste
Peptide models XXIX. cis-trans Isomerism of peptide bonds: Ab initio study on small peptide model compound; the 3D-Ramachandran map of formylglycinamide
No full textThermodynamic separations for cis and trans-amides and formylglycinamide range from 0.00 to 4.77 kcal/mol as computed at various levels of theory. The barriers for trans ← cis-isomerization, for the same set of compounds, computed at various levels of theory, were found between 15.69 and 22.67 kcal/mol. The cis- and trans-Ramachandran maps of formylglycinamide are compared and the topology of the ab initio 3D-Ramachandran map is presented for the first time.Fil: Baldoni, Hector Armando. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - San Luis. Instituto de Matemática Aplicada de San Luis "Prof. Ezio Marchi". Universidad Nacional de San Luis. Facultad de Ciencias Físico, Matemáticas y Naturales. Instituto de Matemática Aplicada de San Luis "Prof. Ezio Marchi"; ArgentinaFil: Zamarbide, Graciela Nidia. Universidad Nacional de San Luis; ArgentinaFil: Enriz, Ricardo Daniel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - San Luis. Instituto Multidisciplinario de Investigaciones Biológicas de San Luis. Universidad Nacional de San Luis. Facultad de Ciencias Físico Matemáticas y Naturales. Instituto Multidisciplinario de Investigaciones Biológicas de San Luis; ArgentinaFil: Jauregui, Esteban Adrian. Universidad Nacional de San Luis; ArgentinaFil: Farkas, Od̈ön. Eötvös Lorand University; HungríaFil: Perczel, András. Universidad Nacional de San Luis; Argentina. Eötvös Lorand University; HungríaFil: Salpietro, Salvatore J.. University of Toronto; CanadáFil: Csizmadia, Imre Gyula. University of Toronto; Canad
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