Radioimmunoassay for parathyroid hormone (PTH): Characterization of commercially available antigens and antisera

Ohne ZusammenfassungSupported by Deutsche Forschungsgemeinschaft.     

EPR spectroscopy of a bidimensional distribution of N-alkyl-pyridinium TCNQ microcrystals: A model for langmuir-blodgett films

We have studied the EPR spectra of a bidimensionally ordered collection of platelike crystallites formed by Tetracyanoquinodimethane (TCNQ) ion salts. We have examinedS=1/2 andS=1 systems which exhibit g tensor and Zero-Field Splitting (ZFS) tensor anisotropy, respectively. EPR spectra change when the magnetic field is rotated with respect to the plane of the teflon support on which the ordered powder adheres. Simulation of such spectra has been exploited to get structural information on the arrangement of the TCNQ molecules stacked inside the crystallite.     

Measurement of non-maxwellian electron distribution functions in hot plasma and the importance for Thomson scattering diagnostics

Thomson scattering measurements show that non-Maxwellian electron distribution functions can occur in Tokamak plasma when the ratio of electron drift velocity to thermal velocity, $\text{ν}{}_{\mathrm{<mtext>D</mtext>}}\text{ν}{}_{\mathrm{<mtext>th</mtext>}}$, is $\text{ν}{}_{\mathrm{<mtext>D</mtext>}}\text{ν}{}_{\mathrm{<mtext>th</mtext>}}\text{? 0.1}$. Consequences for Thomson scattering diagnostics are discussed.     

Multilamellar liposomes formed by phosphatidyl nucleosides: an NMR-HR-MAS characterization

We present an NMR investigation of multilamellar vesicles (MLVs) obtained from phosphatidyl nucleosides, 5'-(1-palmitoyl-2-oleoyl-sn-glycero(3)phospho)cytidine (1), 5'-(1-palmitoyl-2-oleoyl-sn-glycero(3)phospho)inosine (2), and their mixtures. Because of the lower stability of liposomes obtained from 2, studies have been preferentially performed in this case with mixed liposomes 2/POPC (4:1). The investigation is conducted mostly via the HR-MAS technique and the general observation is that the resolution achieved in this way is superior to that obtained in the past with small unilamellar vesicles (SUVs). A full assignment is now possible, which includes the spectral region of the ribose ring and part of the glycerol moiety. Also in the case of MLVs, both for 1 and 2, a stacking between the aromatic bases of the same liposome layer seems to be ruled out, although in both cases the nucleobases appear to be exposed to the aqueous phase. The splitting of both aromatic H-5cyt and H-6cyt is ascribed to the presence of two aggregate populations that may correspond to the two syn and anti conformations observed for cytidine monophosphate in aqueous solution. On the basis of NOESY cross-peaks, it is not always possible to discriminate between inter- and intramolecular interactions; however, the distances found for 1 appear to be compatible with the intramolecular contacts in the anti conformation of the cytidine and also with intermolecular interactions between neighboring molecules of 1. We also find that the glycerol moiety does not seem to interact with the cytidine; however, part of the ribose ring seems to be close to the glycerol moiety. More generally, the interaction of one base with the sugar moiety of a neighboring base, previously observed for SUVs, still appears to be true for MLVs. Studies have been performed also for mixed liposomes obtained from the mixture of 1 and 2, where it is observed that the HR-MAS spectra of the corresponding MLVs are not simply the sum of the spectra of the two isolated components. In particular, there is the presence of a NOESY cross-peak between the aromatic protons H-6cyt and H-2ino, and this permits us to rule out large patchwork domains containing only one nucleoside components in the mixed liposomes. Finally, a study is performed on the time evolution of the system obtained by mixing the previously prepared liposomes of 1 and 2. No interaction is obtained in this case, i.e., the spectra are constitutive, which is consistent with the general picture of liposomes as kinetic traps that are not fusing with each other.     

Interaction independent π bond orders for certain excited states

Particular solutions of the bond order equations are shown for certain excited states, common to different conjugated systems and interaction-independent. The P matrix for these states has: 1 in the principal diagonal (charges), ± 1 in the secondary one, zero otherwise.Consejo Nacional de Investigaciones Cientificas y Técnicas.     

Review about olive oil characterization using high-field nuclear magnetic resonance

In the last years Nuclear Magnetic Resonance (NMR) spectroscopy has found many applications in food analysis. Here, we present a review of the most significant results we have obtained in the olive oil characterization using NMR techniques in combination with multivariate statistical methods.     

On a SC method for determining bond orders in alternant hydrocarbons

A method proposed by Hall allowing direct calculation of bond orders of even AH without computing first the MO's is extended a) so as to take into account some states which include singly occupied MO's and b) to odd AH.Consejo Nacional de Investigaciones Científicas y Técnicas