Influence of a liquid on the natural frequencies of almost circular plates

In this work, the influence of the surrounding fluid on the dynamic characteristics of almost circular plates is investigated. First the natural frequencies and normal modes for the plates in vacuum are calculated by a perturbation procedure. The method is applied for the case of elliptical plates with a low value of eccentricity. The results are compared with other available methods for this type of plates with good agreement. Next, the effect of the fluid is considered. The normal modes of the plate in vacuum are used as a base to express the vibration mode of the coupled plate-fluid system. By applying the Hankel transformation the nondimensional added virtual mass 2 increment (NAVMI) are calculated for elliptical plates. Results of the NAVMI factors and the effect of the fluid on the natural frequencies are given and it is shown that when the eccentricity of the plate is reduced to zero (circular plate) the known results of the natural frequencies for circular plates surrounded by liquid are recovered.

Chemistry and fluid inclusions of the sheeted dike comples of ODP Holes 137-504B and 140-504B

Fluid inclusions in variably altered diabase recovered from Ocean Drilling Program Legs 137 and 140 at Hole 504B, Costa Rica Rift, exhibit fluid salinities up to 3.7 times that of seawater values (11.7 wt% NaCl equivalent) and exhibit uncorrected homogenization temperatures of 125°C to 202°C. The liquid-dominated inclusions commonly are entrapped in zones of secondary plagioclase and may be primary in origin. Fluid salinities are similar to compositions of fluids venting on the seafloor (0.4-7.0 wt% NaCl) and overlap with those measured in metabasalt samples recovered from near the Kane Fracture Zone on the Mid-Atlantic Ridge and from the Troodos ophiolite, Cyprus. The salinity variations may reflect hydration reactions involving formation of secondary mineral assemblages under rock-dominated conditions, which modify the ionic strength of hydrothermal fluids by consuming or liberating water and chloride ion. Rare CO2-CH4-bearing inclusions, subjacent to zones where talc after olivine becomes an important secondary mineral phase (1700 mbsf), may have formed due to local interaction of seawater and olivine at low water to rock ratios. Corrected average fluid inclusion homogenization temperatures exhibit a gradient from 159°C at a depth of 1370 mbsf to 183°C at a depth of 1992 mbsf and are in apparent equilibrium with the present conductive downhole temperatures. These data indicate that fluid inclusions may be used to estimate downhole temperatures if logging data are unavailable. The compositional and thermal evolution of the diabase-hosted fluids may reflect late-stage, off-axis circulation and conductive heating of compositionally modified seawater in the sheeted dike complex at Hole 504B.

Barium isotope fractionation during witherite (BaCO3) dissolution, precipitation and at equilibrium

This study examines the behavior of Ba isotope fractionation between witherite and fluid during mineral dissolution, precipitation and at chemical equilibrium. Experiments were performed in batch reactors at 25 oC in 10-2 M NaCl solution where the pH was adjusted by continuous bubbling of a water saturated gas phase of CO2 or atmospheric air. During witherite dissolution no Ba isotope fractionation was observed between solid and fluid. In contrast, during witherite precipitation, caused by a pH increase, a preferential uptake of the lighter 134Ba isotopomer in the solid phase was observed. In this case, the isotope fractionation factor αwitherite-fluid is calculated to be 0.99993 ± 0.00004 (or Δ137/134Bawitherite-fluid ≈ -0.07 ± 0.04 ‰, 2sd). The most interesting feature of this study, however, is that after the attainment of chemical equilibrium, the Ba isotope composition of the aqueous phase is progressively becoming lighter, indicating a continuous exchange of Ba2+ ions between witherite and fluid. Mass balance calculations indicate that the detachment of Ba from the solid is not only restricted to the outer surface layer of the solid, but affects several (~7 unit cells) subsurface layers of the crystal. This observation comes in excellent agreement with the concept of a dynamic system at chemical equilibrium in a mineral-fluid system, denoting that the time required for the achievement of isotopic equilibrium in the witherite-fluid system is longer compared to that observed for chemical equilibrium. Overall, these results indicate that the isotopic composition of Ba bearing carbonates in natural environments may be altered due to changes in fluid composition without a net dissolution/precipitation to be observed.

Fragm. lat. II 95 - Biblia glossata (Ps 2), mit zusätzlichen Marginalglossen

Vorbesitzer: Stadtarchiv Frankfurt am Main

Fragm. lat. II 10 - Expositio in Cantica canticorum (Ct 1,10 - 2,17)

Trägerband: Ms. Barth. 66; Vorbesitzer: St. Peter Urach; Bartholomaeusstift Frankfurt am Main

Fragm. lat. II 9 - 1. Expositio in Cantica canticorum 2. Theologische Notate

Trägerband: Ms. Barth. 54; Vorbesitzer: Johannes Mushunt de Fulda; Bartholomaeusstift Frankfurt am Main

Fragm. lat. III 34 - Liber Sextus Decretalium (1.4.1 - 4; 1.6.43 - 46; 1.22.2 - 3.3; 3.4.23 - 24), ohne Glosse

Trägerband: Inc. qu. 738; Inc. qu. 913; 'Vocabularius Ex quo'; Vorbesitzer: Dominikanerkloster Frankfurt am Main

Fragm. lat. II 2 - Homiliarium (Sonn- und Ferialtage der Fasten- und Osterzeit, Sonntage nach Pfingsten)

Trägerbände: Inc. oct. 441; Inc. oct. 442; Ms. Praed. 134; Ms. Praed. 164; 'Boethius'; Vorbesitzer: Dominikanerkloster Frankfurt am Main

Fragm. lat. III 22 - Philosophische Texte (1. Quaestiones et solutiones; 2. De modo aeternitatis)

Trägerband: Ms. Barth. 155; Vorbesitzer: Bartholomaeusstift Frankfurt am Main

Fragm. lat. I 47 - Homeliae I 2; I 5 (CC 122,7 Z. 5 - 8 Z. 50; Mt 1,23 - 25; CC 122,32 Z. 1 - 33 Z. 39)

Trägerband: Inc. qu. 1231; Vorbesitzer: Dominikanerkloster Frankfurt am Main

Fragm. lat. I 62 - Bibelkommentar (Apc 5,13; 6,2; 12,1 - 4)

Trägerband: Ms. lat. oct. 26; Ms. lat. oct. 30; Vorbesitzer: Johann Hartmann Beyer