Mobil

About: Mobil is a based out in . It is known for research contribution in the topics: Catalysis & Zeolite. The organization has 7085 authors who have published 10642 publications receiving 237497 citations. The organization is also known as: Socony-Vacuum Oil Company & Standard Oil Company of New York.

High-density turbidity currents; are they sandy debris flows?

Abstract: Conventionally, turbidity currents are considered as fluidal flows in which sediment is supported by fluid turbulence, whereas debris flows are plastic flows in which sediment is supported by matrix strength, dispersive pressure, and buoyant lift. The concept of high-density turbidity current refers to high-concentration, commonly nonturbulent, flows of fluids in which sediment is supported mainly by matrix strength, dispersive pressure, and buoyant lift. The conventional wisdom that traction carpets with entrained turbulent clouds on top represent high-density turbidity currents is a misnomer because traction carpets are neither fluidal nor turbulent. Debris flows may also have entrained turbulent clouds on top. The traction carpet/debris flow and the overriding turbulent clouds are two separate entities in terms of flow rheology and sediment-support mechanism. In experimental and theoretical studies, which has linked massive sands and floating clasts to high-density turbidity currents, the term "high-density turbidity current" has actually been used for laminar flows. In alleviating this conceptual problem, sandy debris flow is suggested as a substitute for high-density turbidity current. Sandy debris flows represent a continuous spectrum of processes between cohesive and cohesionless debris flows. Commonly they are rheologically plastic. They may occur with or without entrained turbulent clouds on top. Their sediment-support mechanisms include matrix strength, dispersive pressure, and buoyant lift. They are characterized by laminar flow conditions, a moderate to high grain concentration, and a low to moderate mud content. Although flows evolve and transform during the course of transport in density-stratified flows, the preserved features in a deposit are useful to decipher only the final stages of deposition. At present, there are no established criteria to decipher transport mechanisms from the depositional record.

Zustandsdiagramm und thermodynamisches Verhalten der Systeme Pd/H2 und Pd/D2 bei normalen Temperaturen; H/D‐Trenneffekte

Abstract: Mit Hilfe von Ubertragungskatalysatoren (UH3-, UD3-, Cu-Pulver) wurden an kompaktem Pd (0,3 und 0,15 mm Folien) Aufbau- und Abbauisothermen mit H2 und D2 gemessen; Temperaturen + 75 bis −78 °C, Drucke 760 bis 10−3 Torr, Atomzahlverhaltnisse n (= H/Pd bzw. D/Pd) von 0,001 bis 0,83. Aus den Messungen im Bereich der α-Phase wurden die chemischen Potentiale des gelosten H bzw. D im Grenzzustand n 0 und ihre auf eine Attraktionswechselwirkung zuruckgehenden, der Konzentration proportionalen Zusatzanteile berechnet. Im Bereich der β-Phase wurden die entsprechenden Zusatzanteile ermittelt. Sie treten hier formal als Repulsionswechselwirkung auf; die Desorptionsenthalpien nehmen linear mit n ab. extrapoliert auf n 1 bis nahezu auf 0. – Eine eingehende Diskussion der im Bereich des Zweiphasengebietes auftretenden Hysterese fuhrt zu dem Schlus, das die Zersetzungsdrucke nahezu den Gleichgewichtsdrucken entsprechen. Aus ihrer Temperaturabhangigkeit ergaben sich die Zersetzungsenthalpien zu ΔHH2 = 9,32 ± 0,1; ΔHD2 = 8,88 ± 0,1 (kcal/mol), die Zersetzungsentropien zu ΔSH20 = 21,8 ± 0,2, ΔSD20 = 23,4 ± 0,2 (cal/grd.mol). Messungen an Pd-Mohr lieferten innerhalb der Fehlergrenzen dieselben Werte. - Fur die Trennfaktoren von H2/D2-Gemischen 1/1 an Pd-Mohr wurde α = 2,25 (50 °C) bis 3,7 (−78 °C) gefunden. By means of “transference catalysts”, for instance pulverized copper, UH3, or UD3, it is possible to measure H2 and D2 adsorption or desorption on bulk palladium (foil, wire) at normal and lower temperatures. This was done on Pd-sheet (0.3 and 0.15 mm) from + 75 to −78 °C; atomic ratios H/Pd and D/Pd were obtained up to n = 0.83. From the results in the α-phase region the chemical potentials of the dissolved gases are calculated for vanishing concentrations, their excess values being attributed to an attractive interaction. Contrary to this, the excess values calculated from the measurements in the β-phase region refer to repulsive interaction. The enthalpies of desorption decrease linearly with n, roughly down to zero if extrapolated to n 1. The hysteresis phenomena observed in the two-phase region are discussed in detail, it being concluded that the pressures of decomposition closely correspond to the equilibrium pressures. From the temperature dependence of these pressures measured in the two-phase region, enthalpies and entropies of decomposition are calculated: ΔHH2 = 9.32 ± 0.1 kcal/mole, ΔHD2 = 8.88 ± 0.1 kcal/mole, ΔSH20 = 21.8 ± 0.2 e.u., ΔSD20 = 23.4 ± 0.2 e.u. Measurements with palladium black, without use of transference catalysts, agree with those obtained on metal sheets. – For equimolar mixtures of H2 and D2, the separation factor is found to range from 2.25 at 50 °C to 3.7 at −78 °C.