Die Molybdänchloride wurden einer erneuten chemischen und physikalischen Untersuchung unterworfen. Die Synthese im Temperaturgefälle lieferte die Verbindungen MoCl4, α‐MoCl3 und MoCl2 (≙Mo6Cl12) in reiner, kristallisierter Form. Auf gleichem Wege wurde die neue Verbindung MoCl3,08 („β‐MoCl3”︁) gefunden. Das im festen Zustande dimere MoCl5 verdampft monomolekular (Massenspektrometer). Der thermische Zerfall (Thermogravimetrie, Massenspektrometer) von MoCl3 erfolgt nach \documentclass{article}\pagestyle{empty}\begin{document}$ 2{\rm MoCl}_{\rm 3} {\rm = MoCl}_{\rm 2} {\rm + MoCl}_{\rm 4},g;{\rm P(MoCl}_{\rm 4} {\rm,800}^ \circ {\rm C) = 12 atm,} $\end{document} während MoCl2 nach \documentclass{article}\pagestyle{empty}\begin{document}$ 2{\rm MoCl}_{\rm 3} {\rm = Mo + MoCl}_{\rm 4},g{\rm zerf}a{\rm llt; P(MoCl}_{\rm 4} {\rm,800}^ \circ {\rm C) = 0,4 atm}{\rm .} $\end{document} . Kristallstrukturuntersuchungen lieferten folgende Informationen: MoCl4 kristallisiert trigonal in einem Schichtengitter mit hexagonal dichter Cl‐Packung. Die Mo‐Atome besetzen 75% der Metallplätze einer Trichloridstruktur, wobei im Mikrobereich Ordnungszustände auftreten. α‐MoCl3 und β‐MoCl3 kristallisieren monoklin in Schichtengittern mit kubisch (α) bzw. hexagonal (β) dichter Cl‐Packung. Die Mo‐Atome sind paarweise als Mo2‐Gruppen aneinander gebunden (MoMo = 2,76 Å). Mo6Cl12(MoCl2) kristallisiert orthorhombisch. Die Struktur enthält [Mo6Cl8]‐Gruppen, die 2‐dimensional unendlich miteinander verknüpft sind: {[Mo6Cl8]Cl2}Cl4/2. Die Bindungsabstände MoMo innerhalb der regulären Mo6‐Oktaeder betragen 2,61 Å. Der Vergleich der Vergleich der Raumbeanspruchung („pro Cl”︁) zeigt, daß diese beim Übergang von den höheren Molybdänchloriden zum Mo6Cl12 wegen dessen sperrigen Aufbaus sprunghaft größer wird. Magnetische Messungen liefern für MoCl5 und MoCl4 nahezu den reinen Spinwert, während die für α‐MoCl3, β‐MoCl3 und Mo6Cl12 gemessenen Werte wegen der MoMo‐Wechselwirkungen sehr viel kleiner sing. Mo6Br12, Mo6J12, W6Cl12, W6Br12 und W6J12 sind mit Mo6Cl12 isotyp.
The influence of an increase in training volume (ITV; February 1989) vs intensity (ITI; February 1990) on performance, catecholamines, energy metabolism and serum lipids was examined in two studies on eight, and nine experienced middle- or long-distance runners; seven participated in both studies. During ITV, mean training volume was doubled from 85.9 km.week-1 (pretrial phase) to 174.6 km within 3 weeks. Some 96%-98% of the training was performed at 67 (SD 8)% of maximal performance. During ITI, speed-endurance, high-speed and interval runs increased within 3 weeks from 9 km.week-1 (pretrial phase) to 22.7 km.week-1 and the total training distance from 61.6 to 84.7 km.week-1. The ITV resulted in stagnation of running velocity at 4 mmol lactate concentration and a decrease in total running distance in the increment test. Heart rate, energy metabolic parameters, nocturnal urinary catecholamine excretion, low density, very low density lipoprotein-cholesterol and triglyceride concentrations decreased significantly; the exercise-related catecholamine plasma concentrations increased at an identical exercise intensity. The ITI produced an improvement in running velocity at 4 mmol lactate concentration and in total running distance in the increment test; heart rate, energy metabolic parameters, nocturnal catecholamine excretion, and serum lipids remained nearly constant, and the exercise-related plasma catecholamine concentrations decreased at an identical exercise intensity. The ITV-related changes in metabolism and catecholamines may have indicated an exhaustion syndrome in the majority of the athletes examined but this hypothesis has to be proven by future experimental studies.
Vestimentiferan tubeworms (siboglinid polychetes) of the genus Lamellibrachia are common members of cold seep faunal communities and have also been found at sedimented hydrothermal vent sites in the Pacific. As they lack a digestive system, they are nourished by chemoautotrophic bacterial endosymbionts growing in a specialized tissue called the trophosome. Here we present the results of investigations of tubeworms and endosymbionts from a shallow hydrothermal vent field in the Western Mediterranean Sea. The tubeworms, which are the first reported vent-associated tubeworms outside the Pacific, are identified as Lamellibrachia anaximandri using mitochondrial ribosomal and cytochrome oxidase I (COI) gene sequences. They harbor a single gammaproteobacterial endosymbiont. Carbon isotopic data, as well as the analysis of genes involved in carbon and sulfur metabolism indicate a sulfide-oxidizing chemoautotrophic endosymbiont. The detection of a hydrogenase gene fragment suggests the potential for hydrogen oxidation as alternative energy source. Surprisingly, the endosymbiont harbors genes for two different carbon fixation pathways, the Calvin-Benson-Bassham (CBB) cycle as well as the reductive tricarboxylic acid (rTCA) cycle, as has been reported for the endosymbiont of the vent tubeworm Riftia pachyptila. In addition to RubisCO genes we detected ATP citrate lyase (ACL – the key enzyme of the rTCA cycle) type II gene sequences using newly designed primer sets. Comparative investigations with additional tubeworm species (Lamellibrachia luymesi, Lamellibrachia sp. 1, Lamellibrachia sp. 2, Escarpia laminata, Seepiophila jonesi) from multiple cold seep sites in the Gulf of Mexico revealed the presence of acl genes in these species as well. Thus, our study suggests that the presence of two different carbon fixation pathways, the CBB cycle and the rTCA cycle, is not restricted to the Riftia endosymbiont, but rather might be common in vestimentiferan tubeworm endosymbionts, regardless of the habitat.
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