Über Spurenelementbestimmungen in Leberproben Mittels Protoneninduzierter Röntgenfluoreszenz (Pixe)

Multi-element-analysis by PIXE in respect to medical applications is discussed. Examples of trace-element determinations in liver tissues are given, demonstrating the applicability and usefulness of this rather new analytical technique.      

Primary methods of measurement in chemical analysis

 Primary methods of measurement have a central function in metrology. They are an essential component in the realisation of the SI units and therefore are indispensable for establishing traceability of measurements of all kinds of physical quantities to the corresponding SI units. This is also true for chemical analysis. Gravimetry, titrimetry, coulometry, and isotope dilution mass spectrometry (IDMS) are evaluated with regard to their potential to be primary methods according to a general definition of primary methods recently given by the Comité Consultatif pour la Quantité de Matière (CCQM). Optical absorption spectrometry and methods based on colligative properties are also considered. A general scheme for establishing traceability of chemical measurements to the SI units using primary methods is discussed. Received: 17 April 1997 · Accepted: 9 August 1997     

Effects of <Emphasis Type="Italic">L</Emphasis>-Carnitine on Sucrose-Induced Hyperlipidaemia

Summary. L-Carnitine, L-(−)-β-hydroxy-γ-trimethylaminobutyrate, plays an important role as a factor necessary for the transport of long-chain fatty acids into the mitochondria. In order to investigate the influence of L-carnitine on hyperlipidaemias, the experimental model of the sucrose-induced hypertriglyceridaemia of the rat was used. In these experiments L-carnitine in the dose of 11 mg per day and 100 g body weight (over the period of 1 week) was able to antagonize the sucrose-induced hypertriglyceridaemia and the increase of serum free fatty acid level in female rats of the Wistar strain. Carnitine administration did not change the activities of lipogenic enzymes and fatty acid synthesis in the liver. However, L-carnitine increases the rate of hepatic fatty acid oxidation. Our results indicate a hypotriglyceridemic and free fatty acid lowering effect of L-carnitine, and suggest the use of this compound in the therapy of hyperlipidaemias.     

Mobility of muons in Cu below 2 K

We have performed transverse fieldSR experiments on several different samples of copper in the temperature range below 2 K, including isotope separated Cu and impurity doped polycrystalline Cu.We do not observe any strong effect of the isotope composition of the sample. A⁶³Cu and a natural Cu sample of identical purity both yield 0.16s^–1 for the low-temperature plateau, while an increased linewidth in the⁶⁵Cu case may be related to the strong effects of Fe impurities.Careful transverse field measurements on large single crystals at 0.08 K reveal non-Gaussian lineshapes in accordance with the picture of diffusing muons at this temperature. This allows us to reject several of the existing models for muon behaviour in copper below 2 K.     

Delivery of Benzoporphyrin Derivative, a Photosensitizer, into Atherosclerotic Plaque of Watanabe Heritable Hyperlipidemic Rabbits and Balloon-Injured New Zealand Rabbits

Abstract— In this study we compared the plasma distribution and arterial accumulation of a photosensitizer, benzoporphyrin derivative (BPD), in two models of atherosclerosis: the spontaneous lesions of the Watanabe heritable hyperlipidemic (WHHL) rabbit and induced lesions of the balloon-injured, cholesterol-fed New Zealand white (NZW) rabbit. Selective uptake and retention of a photosensitizer by the abnormal portion of a vessel is a necessity in order for photodynamic therapy to become a successful modality for inhibition of intimal hyperplasia, selective removal of atherosclerotic tissue or imaging of diseased arteries. Liposome-based formulations were compared to freshly isolated native low density lipoprotein (LDL) and acetylated-LDL (Ac-LDL) as delivery vehicles for BPD. Plasma distribution of the photosensitizer was analyzed by KBr density gradient ultracentrifuga-tion. Although the delivery vehicle influenced plasma distribution immediately postinjection, BPD subsequently partitioned according to the plasma concentration of the lipoproteins. Photosensitizer level in plaque and normal artery specimens was determined by ethyl acetate extraction and spectrofluorometric measurement. The measurement of BPD in normal and atherosclerotic arterial tissue demonstrated a selective accumulation in atherosclerotic tissue. Preassociation with LDL and Ac-LDL enhanced accumulation of BPD in atherosclerotic tissue when compared with normal artery (mean ratios of 2.8 and 4.1 were achieved, respectively). These results indicate that the preferential uptake of BPD by atherosclerotic plaque can be enhanced by preassociation with plasma lipoproteins, suggesting that light activation could lead to a highly selective destruction of diseased vascular tissue.     

Die Reaktion von SeCl4 mit Übergangsmetalltetrachloriden. Synthese und Kristallstrukturen von (SeCl3)2MCl6 mit M = Zr,Hf, Mo,Re

The Reaction of SeCl₄ with Transition Metal Tetrachlorides. Synthesis and Crystal Structures of (SeCl₃)₂MCl₆ with M = Zr, Hf, Mo, Re The transition metal tetrachlorides ZrCl₄, HfCl₄ and MoCl₄ react with SeCl₄ in closed ampoules at temperatures of 140°C to (SeCl₃)₂MCl₆ (M = Zr, Hf, Mo) which are all isotypic and crystallize in the (SeCl₃)₂ReCl₆ structure type (orthorhombic, Fdd2, Z = 8, lattice constants for M = Zr: a = 1165.7(1)pm, b = 1287.2(2)pm, c = 2180.2(2)pm; for M = Hf: a = 1162.9(2)pm, b = 1285.0(2)pm, c = 2178.2(3)pm; for M = Mo: a = 1153.8(1)pm, b = 1267.7(1)pm, c = 2147.4(2)pm). The Cl^? ions form a hexagonal closest packing with one fourth of the octahedral holes filled by Se⁴⁺ and M⁴⁺ in an ordered way. The MCl₆ octahedra are regular, the SeCl₆ octahedra are distorted with 3 short and 3 long Se? Cl bonds (mean 215 pm and 287 pm). The structures can thus be regarded as built of SeCl₃⁺ and MCl₆^2? ions. Magnetic susceptibility measurements show for M = Zr the expected diamagnetic behavior, for M = Mo and Re paramagnetic behavior according to the Curie-Weiss law with magnetic moments of 2.5 B. M. for M = Mo and 3.7 B. M. for M = Re corresponding to 2 and 3 unpaired electrons respectivly.     

Use of Dimethylsilyl Ethers for Characterizing Primary Aliphatic Alcohols: A comparison of mass spectrometric fragmentation of di- and trimethylsilyl derivatives

Mass spectral fragmentation patterns of dimethylsilyl (DMS) ethers of primary unbranched, branched, and secondary unbranched aliphatic alcohols in the C₅ to C₁₀ range are compared with those of the corresponding trimethylsilyl (TMS) derivatives. Unlike their TMS analogues, DMS ethers of primary alcohols exhibit pronounced rupture of the C? C bond adjacent to the oxygen atom within the alkyl moiety (loss of an alkyl radical R) in marked preference to cleavage within the silyl substituent (loss of CH₃). Within this class of compounds, complementary preparation of DMS derivatives can therefore be used to establish or to confirm the site, and thus the primary nature of the hydroxyl group, whereas preparation of TMS ethers may be of advantage in deducing molecular size. For the derivatives of secondary alcohols this diagnostically useful difference in fragmentation behaviour is not observed.     

Comparison of Si-O-C interfacial bonding of alcohols and aldehydes on Si(111) formed from dilute solution with ultraviolet irradiation

Aliphatic alcohols and aldehydes were reacted with the Si(111)-H surface to form Si-O-C interfacial bonds from dilute solution by using ultraviolet light. The resulting monolayers were characterized by using transmission infrared spectroscopy, spectroscopic ellipsometry, and contact angle measurements. The effect of different solvents on monolayer quality is presented. The best monolayers were formed from CH(2)Cl(2). The optimized monolayers were thoroughly characterized to determine the film structure and monolayer stability. The UV-promoted, alcohol-functionalized, and aldehyde-functionalized monolayers are of comparable quality to those previously prepared by other means. Although both molecules are tethered through a Si-O-C bond, the film reactivity is distinctly different with the aldehyde films being more chemically resistant. The differences in chemical reactivity, vibrational spectra, hydrophobicity, and ellipsometric thickness between the alcohol and aldehyde monolayers are attributed to a difference in molecular coverage and monolayer formation.     

UV-holographic gratings in TS-diacetylene single crystals

Holographic gratings with grating periods between 0.37 m and 4.4 m, respectively, were recorded on the surface of TS-diacetylene single crystals by two interfering 257 nm laser beams. Diffraction efficiencies of up to 35 % were obtained for readout with red light of = 633 nm. The main modulation mechanism was phase modulation. The spatial resolution was better than 1600 lines/mm. The upper limit of the polymer chain length was 0.6 m. The holographic sensitivity was 4.5 cm²/J for immediate read-out at 633 nm without processing after exposure. — A weakly exposed latent hologram may be developed simply by gentle annealing the crystal which increases the sensitivity by one order of magnitude.