Chiral recognition for the complexation dynamics of β-cyclodextrin with the enantiomers of 2-naphthyl-1-ethanol

The focus of this study is to understand the origin of the chiral recognition for a host–guest system containing complexes with different stoichiometries. Each enantiomer of 2-naphthyl-1-ethanol forms two different 1:1 complexes with β-cyclodextrin, leading to the formation of three different 2:2 complexes. One of these 2:2 complexes leads to excimer emission of the guest. Fluorescence studies were employed to determine the binding isotherms for the 1:1 and 2:2 complexes. No chiral discrimination was directly observed for the formation of the 1:1 complexes, while higher equilibrium constants (29% from binding isotherms and 40% from kinetic studies) were observed for the formation of the 2:2 complexes with (R)-2-naphthyl-1-ethanol when compared to the formation of the 2:2 complexes formed from (S)-2-naphthyl-1-ethanol. The relaxation kinetics was studied using stopped-flow experiments. The formation of the 2:2 complexes was followed by detecting the excimer emission from one of the 2:2 complexes. The relaxation kinetics was faster for (S)-2-naphthyl-1-ethanol, where a higher dissociation rate constant, by 47%, was observed, suggesting that the chiral discrimination occurs because the interaction between two cyclodextrins is more favorable for the complexes containing (R)-2-naphthyl-1-ethanol when compared to (S)-2-naphthyl-1-ethanol. The same overall equilibrium constants were observed for the 1:1 complexes with both enantiomers showing that at a given cyclodextrin concentration the sum of the two types of 1:1 complexes is the same for both enantiomers. However, analysis of the binding isotherms indicates that the ratio between the two different 1:1 complexes for each enantiomer was different for (R)- and (S)-2-naphthyl-1-ethanol

Evaluierung potentieller Torfersatzstoffe für den Erwerbsgartenbau mit bodenkundlichen Methoden

Mit dem Torfabbau für gartenbauliche Zwecke sind vielfältige negative Auswirkungen verknüpft: Veränderung des Landschaftswasserhaushalts, Treibhausgas-Emissionen, Landschaftswandel, Verlust der biologischen Vielfalt. Der Einsatz von Torfersatzstoffen im Erwerbsgartenbau wie z.B. Rindenhumus, Komposte oder Kokosfasern findet bisher nur in einem geringen Umfang statt, da sie andere Eigenschaften als Torf aufweisen und daher ein potentielles Kulturrisiko darstellen. Zudem können diese Stoffe auch zu ökologischen Problemen führen, z.B. durch lange Transportwege bei der Beschaffung von Kokosfasern. Daher ist es wichtig systematische Untersuchungsverfahren für die Analyse von Torfersatzstoffen mit hoher Kultursicherheit zu entwickeln. Um den Untersuchungsaufwand zu minimieren, soll ein Entscheidungsbaum entwickelt werden, anhand dessen verschiedene Parameter systematisch untersucht werden. Dieser soll schon in frühen Stadien indizieren, ob sich ein Rohstoff als Substratausgangsstoff eignet, bedingt eignet oder verworfen werden muss. Hierzu werden klassische Untersuchungsverfahren (VDLUFA, DIN EN) zur Untersuchung der chemischen, physikalischen und biologischen Eigenschaften der Substratausgangsstoffe eingesetzt wie z.B. zur N-Immobilisierung und zum Wasser- und Lufthaushalt. Diese werden mit bodenkundlichen Methoden wie z.B. Inkubations- und Stabilisotopenversuche kombiniert und weiter entwickelt. Die weiter entwickelten Methoden sollen zu einer verbesserten Aussagefähigkeit bezüglich der Kultursicherheit beitragen. Im Rahmen dieser Studie werden auf diese Weise mehrere potentielle Substratausgangsstoffe (Erle, Schilf, Rohrkolben, Heide) getestet. Es werden erste Ergebnisse der Labor- und Gewächshausversuche dieser potentiellen Substratausgangsstoffe präsentiert

Nanogranular MgB2 thin films on SiC buffered Si substrates prepared by in-situ method

MgB2 thin films were deposited on SiC buffered Si substrates by sequential electron beam evaporation of B-Mg bilayer followed by in-situ annealing. The application of a SiC buffer layer enables the maximum annealing temperature of 830 C. The Transmission Electron Microscopy analysis confirms the growth of a nanogranular MgB2 film and the presence of a Mg2Si compound at the surface of the film. The 150-200 nm thick films show a maximum zero resistance critical temperature TC0 above 37 K and a critical current density JC ~ 106 A/cm2 at 11K.Comment: 7 pages, 6 figures, submitted to Applied Physics Letter

Analysis of Toth Surface Elements by Ion beam Analysis

To examine the applicability of elastic recoil detection analysis ERDA in studying element constituents of dental hard tissues. The concentration of all elements using high energy heavy ions was detected in extracted teeth of both dentitions. The main elements present in enamel calcium, phosphorus, oxygen, hydrogen , along with nitrogen, carbon, fluorine, sodium, magnesium and zinc, were measured. Concentrations and depth profiles were calculated and compared with simulation data generated using two programs, KONZERD and SIMNRA. Enamel calcium, phosphorus, oxygen, hydrogen, nitrogen, carbon, fluorine, sodium, magnesium and, occasionally, zinc were detected. One third of samples showed a constant concentration of the constituents over the analyzed depth, whereas the remaining samples had pronounced surface contaminations of carbon and nitrogen. Although calculation of concentrations with KONZERD gave expected values, simulation with SIMNRA was not possible since no agreement could be obtained between simulated and measured results for the element

Spectroscopic factors for bound s-wave states derived from neutron scattering lengths

A simple and model-independent method is described to derive neutron single-particle spectroscopic factors of bound s-wave states in $^{A+1}Z = ^{A}Z \otimes n$ nuclei from neutron scattering lengths. Spectroscopic factors for the nuclei ^{13}C, ^{14}C, ^{16}N, ^{17}O, ^{19}O, ^{23}Ne, ^{37}Ar, and ^{41}Ar are compared to results derived from transfer experiments using the well-known DWBA analysis and to shell model calculations. The scattering length of ^{14}C is calculated from the ^{15}C_{g.s.} spectroscopic factor.Comment: 9 pages (uses revtex), no figures, accepted for publication in PRC, uuencoded tex-files and postscript-files available at ftp://is1.kph.tuwien.ac.at/pub/ohu/Thermal.u

Reaction rates for Neutron Capture Reactions to C-, N- and O-isotopes to the neutron rich side of stability

The reaction rates of neutron capture reactions on light nuclei are important for reliably simulating nucleosynthesis in a variety of stellar scenarios. Neutron capture reaction rates on neutron-rich C-, N-, and O-isotopes are calculated in the framework of a hybrid compound and direct capture model. The results are tabulated and compared with the results of previous calculations as well as with experimental results.Comment: 33 pages (uses revtex) and 9 postscript figures, accepted for publication in Phys. Rev.

Quasi-fission reactions as a probe of nuclear viscosity

Fission fragment mass and angular distributions were measured from the ^{64}Ni+^{197}Au reaction at 418 MeV and 383 MeV incident energy. A detailed data analysis was performed, using the one-body dissipation theory implemented in the code HICOL. The effect of the window and the wall friction on the experimental observables was investigated. Friction stronger than one-body was also considered. The mass and angular distributions were consistent with one-body dissipation. An evaporation code DIFHEAT coupled to HICOL was developed in order to predict reaction time scales required to describe available data on pre-scission neutron multiplicities. The multiplicity data were again consistent with one-body dissipation. The cross-sections for touch, capture and quasi-fission were also obtained.Comment: 25 pages REVTeX, 3 tables, 13 figures, submitted to Phys. Rev

Glycoconjugate Data Bank:Structures—an annotated glycan structure database and N-glycan primary structure verification service

Glycobiology has been brought to public attention as a frontier in the post-genomic era. Structural information about glycans has been accumulating in the Protein Data Bank (PDB) for years. It has been recognized, however, that there are many questionable glycan models in the PDB. A tool for verifying the primary structures of glycan 3D structures is evidently required, yet there have been no such publicly available tools. The Glycoconjugate Data Bank:Structures (GDB:Structures, http://www.glycostructures.jp) is an annotated glycan structure database, which also provides an N-glycan primary structure (or glycoform) verification service. All the glycan 3D structures are detected and annotated by an in-house program named ‘getCARBO’. When an N-glycan is detected in a query coordinate by getCARBO, the primary structure of the glycan is compared with the most similar entry in the glycan primary structure database (KEGG GLYCAN), and unmatched substructure(s) are indicated if observed. The results of getCARBO are stored and presented in GDB:Structures