The specific heat of two cubic laves compounds: TiBe2 and ThMg2

The low temperature specific heats of two isomorphous Laves compounds, TiBe₂ and ThMg₂, have been measured. The shape of the transition for the itinerant antiferromagnet TiBe₂ is characteristic of magnetic ordering; the entropy of this transition is quite small, approximately 107 mJ/mole-K, a further indication of itinerancy. The γ, proportional to the density of states, is 42 mJ/mole-K² for TiBe₂, and the Debye temperature, θ_D, is 650 K. These numbers are compared to those for the itinerant ferromagnet, ZrZn₂. The results for ThMg₂ are γ=9.2 mJ/ mole-K² and θ_D = 217 K. Results for both compounds are discussed in regards to the theory of Enz and Matthias.     

On the reaction between coumarins and hydroxylamine

The Posner reaction between coumarin and hydroxylamine was studied and extended to several substituted coumarins. Isolation of some significant reaction intermediates permitted rationalization of a possible reaction pathway.     

Sterine in Weidegräsern

During the course of investigations concerned with a cattle disease (Weidekrankheit) in Austrian alpine regions, it became of interest to examine the sterol fractions of some typical grasing plants, since it seemed possible that a biological connection exists between the phytosterols, Vitamin D and related compounds and the cause of the Weidekrankheit.The sterol contents of eight different species of Austrian alpine grasses especially of Trisetum flavescens, were studied by gas-liquid chromatography and mass spectrometry. All contained sitosterol as the main component, besides cholesterol, campesterol, stigmasterol, ⁷-cholestenol and ^{7,24 (28)}-stigmastadienol.The aim of this examination was to establish whether there is an influence of fertilizing on the content of the above mentioned compounds: no remarkable difference between the sterol contents of fertilized and non-fertilized grasses could be found.     

Structural reinvestigation of ammonium hypophosphite: was dihydrogen bonding observed long ago?

The past decade has seen the explosive emergence of "dihydrogen bonds", interactions between the electrons of M-H sigma-bonds, where M is less electronegative than H (M = Al, B, Ga, Ir, Mo, Mn, Os, Re, Ru, W) and traditional proton donors. But 70 years ago, such an interaction was proposed by Zachariasen and Mooney [J. Chem. Phys. 1934, 2, 34-37] on the basis of their single-crystal X-ray diffraction structure (heavy atoms positions only) of ammonium hypophosphite (NH(4)H(2)PO(2)). We redetermined this structure at high resolution with a focus on the hydrogen atoms, using a modern diffractometer equipped with a CCD detector. Molecular orbital calculations were performed to investigate the charge density and the bond polarity of the P-H bonds and to assess their potential for participation in dihydrogen bonds. Neither the theory nor the X-ray structure supports the original claim of H...H interactions in this salt.     

New synthetic approach to yttrium hydroxoacetates, structural characterization, and use as a precursor for coated conductors

A novel synthetic approach is given for the preparation of a metal-organic lanthanide sol-gel precursor solution and its application for the production of coated conductors. Besides all other problems concerning the technical process itself, the key to a successful deposition of oxide layers is the choice of the precursor solution and the understanding of the mechanism of deposition. Moreover, the isolation and characterization of the species involved in the reaction is very important. Regarding the complex process occurring during the formation of the surface layer, it is obvious that the best choice should have a compound already containing the final composition of the layer. Two compounds of composition [Y(OAc)3(H2O)2]2 and [Y(OAc)3]2(H2O) were isolated from their precursor solution and characterized by X-ray structural analysis. A short outlook will give an insight into the possible bonding mechanisms of the surface layer. These experiments were made with the mixed metal-oxide system yttrium-stabilized zirconium oxide, which is widely used as a substrate for superconducting oxides. A study of the structure of hydrated yttrium acetates, by single-crystal X-ray diffraction, infrared spectra, and elemental analysis demonstrates that there are two separate structures for hydrated yttrium acetates, which play a role as an intermediate in the building of ceramic oxide layers for coated conductors.     

Synthesis of linear aldehydes from internal olefins in water

We show here, for the first time, that the carbonylation of internal olefins in a biphasic water system is possible. It is shown that control of the pH and CO partial pressure are important factors for successful reactions. Interestingly, the water-soluble catalyst leads to significantly higher regioselectivity compared to similar catalysts soluble in organic solvents. The obtained n/i-selectivities exceed all known literature data and the catalyst can be easily reused several times.     

Solvent-free methylthiomethyllithium [LiCH2SMe]infinity: solid state structure and thermal decomposition

Solvent-free [LiCH2SMe]infinity forms a layer structure consisting of four- (Li2C2), five- (Li2CS2), and six-membered (Li2C2S2) rings in the solid state; the compound violently explodes upon heating to T=160+/-5 degrees C under an argon atmosphere.     

Identification of novel biomarker candidates by differential peptidomics analysis of cerebrospinal fluid in Alzheimer's disease

The objective of this work was the application of peptidomics technologies for the detection and identification of reliable and robust biomarkers for Alzheimer's disease (AD) contributing to facilitate and further improve the diagnosis of AD. Using a new method for the comprehensive and comparative profiling of peptides, the differential peptide display (DPD), 312 cerebrospinal fluid (CSF) samples from AD patients, cognitively unimpaired subjects and from patients suffering from other primary dementia disorders were analysed as four independent analytical sets. By combination with a cross validation procedure, candidates were selected from a total of more than 6,000 different peptide signals based on their discriminating power. Twelve candidates were identified using mass-spectrometric techniques as fragments of the possibly neuroprotective neuroendocrine protein VGF and another one as the complement factor C3 descendent C3f. The combination of peptide profiling and cross validation resulted in the detection of novel potential biomarkers with remarkable robustness and a close relation to AD pathophysiology.