Sagnac Effect of Gödel's Universe

We present exact expressions for the Sagnac effect of Gödel's Universe. For this purpose we first derive a formula for the Sagnac time delay along a circular path in the presence of an arbitrary stationary metric in cylindrical coordinates. We then apply this result to Gödel's metric for two different experimental situations: First, the light source and the detector are at rest relative to the matter generating the gravitational field. In this case we find an expression that is formally equivalent to the familiar nonrelativistic Sagnac time delay. Second, the light source and the detector are rotating relative to the matter. Here we show that for a special rotation rate of the detector the Sagnac time delay vanishes. Finally we propose a formulation of the Sagnac time delay in terms of invariant physical quantities. We show that this result is very close to the analogous formula of the Sagnac time delay of a rotating coordinate system in Minkowski spacetime.     

Quinazolines and 1,4-benzodiazepines. XCV. Synthesis of 1,4-benzodiazepines by ring expansion of 2-chloromethylquinazolines with carbanions

1,4-Benzodiazepines bearing a carbon substituent at the 2-position were obtained by reaction of 2-chloromethylquinazoline 3-oxides with stabilized carbanions. The carbanions of alkyl acetates, N,N-disubstituted acetamides, acetonitrile, dimethylsulfone, N,N-dimethyl methanesulfonamide and 2-methylpyridine were successfully applied. The conversion of some of the 2-carbon substituted 1,4-benzodiazepines to imidazo[1,5-a][1,4]benzodiazepines and [1,2,5]oxadiazino[5,4-a][1,4]benzodiazepines is described.     

Enantiospecific activity of tetracyclic PAF-antagonists

The syntheses of two enantiomeric tetracyclic compounds, the thieno[3,2-f][pyrrolo[2,1-c][1,2,4]triazolo[4,3-a][1,4]diazepines 10a and 10b are described. Testing of these enantiomers as inhibitors of platelet activating factor (PAF) revealed good enantiospecificity, meaning that one enantiomer is responsible for the observed biological activity.     

Die Komplexe der Hexamine «penten» und «ptetraen» Thermodynamik ihrer Bildung in wässeriger Lösung

The two hexamines (H₂N? CH₂? CH_{2? )2}N? (CH_2)n? N(? CH₂? CH₂? NH₂₎₂, «penten» (n = 2) and «ptetraen» (n=3) have been investigated as chelating agents for COIII (preparative Study) and some of the divalent metal ions (potentiometric and calorimetric studies). Both amines function as sexadentate ligands for Co^III, Co^II and Ni^II, but one of the terminal aminogroups is much easier detached from the metal in case of M (penten)^v+ than in case of M(ptetraen)^v+, thus revealing more strain in the fivemembered chelate rings of the girdle plane of the «penten» complexes. On the other hand, the sixmembered chelate ring in M(ptetraen)^v+ is more strained than the five-membered ring comprising the tertiary nitrogen atoms of M(penten)^v+ Cu^II and Zn^II coordinate with both ligands only 5 of the 6 basic nitrogen atoms present. Both hexaamines function as sexadentates again with Mn^II, but the metal is coordinated with a molecule of water in addition to the 6 nitrogen atoms in the «penten» complex in contrast to the «ptetraen» complex. The thermodynamic functions for the protonation of the hexamines and for the addition of metal ions in aqueous solution are understood in almost every detail. The dielectric shielding of the charges of the reactants exerted by the solvent has to be taken into account; it is reduced by electrostriction as well as by an increase in temperature. It is shown that the approach of charges of equal sign often is an exothermic process.     

Quinazolines and 1,4-benzodiazepines. LXXXVII. Synthesis of 1- and 3-phenylimidazo[1,5-a] [1,4]benzodiazepines

The synthesis of the 1-phenylimidazobenzodiazepine 5 from 1 and the anion of the nitrone 2 is described. The 3-phenyl-derivative 14 was prepared via the ammo alcohol 11 which was obtained by condensation of the nitrosamine 9 with benzaldehyde followed by catalytic hydro-genolysis of the nitroso group.     

Os(VIII)-catalysed oxidation of sulfides by sodium salt of N-chlorobenzenesulfonamide

Catalytic activity of Os(VIII) in the oxidation of some twenty organic sulfides with sodium salt of N-chlorobenzenesulfonamide (CAB) has been investigated in alkaline (pH8.7) t-butanol–water (1:1 v/v) medium. Significant retarding influence of [OH⁻] on the reactivity is exhibited. The catalysed reaction is strongly accelerated in the presence of Hg(II). Imperfections are observed in the linear Hammett relationship in the case of –NO₂ substituents.     

Stereoselective Hydrolysis of Substituted Cyclopropanedicarboxylates with Pig Liver Esterase

The hydrolysis of the meso-cyclopropane-1,2-dicarboxylates 1a - 3a , 4 , 5a , 6a , and 9 , containing various substituents at C(3), and of the rac-3-phenylcyclopropane-1,2-dicarboxylates 7a , 8a , and 10 with pig liver esterase (PLE) is described. The stereoselectivtty and absolute configurations of the products were determined. An interpretation of results was attempted on the basis of a recent active-site model for PLE.     

Raman spectroscopic investigation on the microenvironment of the liver tissues of Zebrafish (Danio rerio) due to titanium dioxide exposure

Nano titanium dioxide (nTiO₂), generally considered to be toxicologically inert, is manufactured in large quantities and extensively applied in consumer products. The small size and large surface area endow them with an active group or intrinsic toxicity. Advances in instrumentation are making Raman spectroscopy the tool of choice for an increasing number of (bio) chemical applications. One of the great advantages of this technique is its ability to provide information on the concentration, structure and interaction of biochemical molecules in their microenvironments within intact cells and tissues, non-destructively. Zebrafish (Danio rerio), one of the most important vertebrate model organisms used in developmental biology, are increasingly used in biomedical research, particularly as a model of human disease. In the present work, an attempt is made to study the effect of titanium dioxide, both nano and bulk, on the microenvironment of the liver tissues of Zebrafish using FT-Raman spectroscopy. The results of the present study suggest that TiO₂ exposure demonstrate a marked influence on the microenvironments of the liver tissues of Zebrafish. A shift to a higher wavenumber and an increase in the intensity of the band at ∼1087 cm⁻¹ in the TiO₂ exposed tissues suggest that some of the conformational changes resulting from the alkali recovery process takes place due to TiO₂ exposure. The decreased intensity ratio (I₃₂₂₀/I₃₄₀₀) observed in the titanium-exposed tissues suggests a decreased water domain size, which could be interpreted in terms of weaker hydrogen-bonded molecular species of water in the TiO₂ exposed tissues. The observed shift of COO⁻ bands to higher frequencies shows the disruption of salt bridges as a result of a change in the oppositely charged partners and due to the enhanced random coil conformation. The variation in the intensity ratio of the tyrosyl doublet (I₈₅₈/I₈₂₅) indicates variation in the hydrogen bonding of the phenolic hydroxyl group due to TiO₂ exposure. The results further suggest that the microenvironments are greatly altered due to titanium nano exposure when compared to titanium bulk. In conclusion, the results indicate that FT-Raman spectroscopy might be a useful tool for rapid assessment of nano particle biological interactions.