Interpretation of sorption and diffusion data in porous solids

1983 ◽  
Vol 22 (1) ◽  
pp. 150-151 ◽  
Author(s):  
Rutherford Aris
Keyword(s):  
Porous Solids ◽  
Diffusion Data ◽  
And Diffusion

Concentration fluctuations in water–methanol mixtures as studied by ultrasonic absorption

1976 ◽  
Vol 54 (3) ◽  
pp. 355-366 ◽  
Author(s):  
William D. T. Dale ◽  
Peter A. Flavelle ◽  
Peeter Kruus
Keyword(s):  
Experimental Data ◽  
Intermolecular Interactions ◽  
Vapour Pressure ◽  
Reasonable Agreement ◽  
Concentration Fluctuations ◽  
Ultrasonic Absorption ◽  
Diffusion Data ◽  
And Diffusion ◽  
Excess Absorption

Measurements of the ultrasonic absorption and velocity, and viscosity have been carried out in the system methanol–water at 0, 15, and 25 °C at frequencies from 10 to 50 MHz. The data show the existence of two maxima in the excess absorption as a function of composition. The existence of the two maxima are predicted by the Romanov–Solovyev theory relating the absorption to concentration fluctuations. The magnitude of the excess absorption is calculated at 25 and 0 °C from density, vapour pressure, and diffusion data. New experimental data on density and vapour pressure are presented for this system at 0 °C. The calculated excess absorption is in reasonable agreement with the measured. This indicates that any specific localized intermolecular interactions present in this system could be responsible for at best a smaller portion of the excess ultrasonic absorption, as longer range concentration fluctuations account for essentially all of the excess. Ultrasonic data on the systems methanol–octanol and n-propanol–water are also presented in the course of examining the generality of these phenomena.

Relation Between Structure and Diffusion in Nanostructured Porous Solids and in Lipid Membranes

2005 ◽  
Vol 899 ◽  
Author(s):  
Sergey Vasenkov ◽  
Jörg Kärger
Keyword(s):  
Lipid Membranes ◽  
Molecular Transport ◽  
Domain Size ◽  
Porous Solids ◽  
Diffusion Studies ◽  
Lipid Diffusion ◽  
Effective Diffusivities ◽  
Pfg Nmr ◽  
Fcc Catalysts ◽  
And Diffusion

AbstractPulsed field gradient (PFG) NMR technique has been applied to study molecular transport in two different types of nanostructured materials, viz. in fluid catalytic cracking (FCC) catalysts and in lipid membranes. Diffusion studies have been performed for a broad range of molecular displacements covering displacements that are as small as a fraction of a micron. The effective diffusivities recorded on various length scales are used to evaluate the relevance of various transport modes in the particles of FCC catalysts for the rate of molecular exchange between catalyst particles and the surrounding atmosphere. This rate is shown to be primarily related to the diffusion in the meso- and macropores of the particles under the condition of fast molecular exchange between these pores and the zeolite crystals located in the particles. Studies of lipid membranes are focused on developing fundamental understanding of the influence of various types of domains on lateral mobility of lipids. A meaningful study of this influence requires an ability of monitoring lipid diffusion for different displacements that are smaller and larger than the domain size. First PFG NMR data along this direction are presented.

scholarly journals Polymeric structure of a high-molecular-weight glycoprotein from bovine cervical mucus

1983 ◽  
Vol 215 (3) ◽  
pp. 701-704 ◽  
Author(s):  
F A Meyer
Keyword(s):  
Molecular Weight ◽  
Light Scattering ◽  
High Molecular Weight ◽  
Bond Cleavage ◽  
Cervical Mucus ◽  
Disulphide Bond ◽  
Polymeric Structure ◽  
Diffusion Data ◽  
And Diffusion

A 16 X 10(6)-Mr glycoprotein isolated from bovine oestrus cervical mucus when reduced under conditions where disulphide-bond cleavage is essentially quantitative produces chains whose Mr from light-scattering and from sedimentation and diffusion data is some 4 X 10(6)-5 X 10(6). Pronase digestion of the chains indicates that glycosylated sequences of Mr 0.3 X 10(6)-0.5 X 10(6) are interspersed with enzyme-susceptible non-glycosylated peptide sequences.

Dynamic analysis of viscous flow and diffusion in porous solids

AIChE Journal ◽  
1989 ◽  
Vol 35 (8) ◽  
pp. 1370-1375 ◽  
Author(s):  
Gülşen Do??u ◽  
Ahmet Pekediz ◽  
Timur Do??u
Keyword(s):  
Dynamic Analysis ◽  
Viscous Flow ◽  
Porous Solids ◽  
And Diffusion

Ordering Kinetics and Diffusion in Some L12 Alloys

1985 ◽  
Vol 57 ◽  
Author(s):  
Robert W. Cahn
Keyword(s):  
Relaxation Time ◽  
Critical Temperature ◽  
The Self ◽  
Inverse Relation ◽  
Diffusion Data ◽  
Ordering Kinetics ◽  
Ordered Alloys ◽  
And Diffusion

AbstractA comparison is made of, ordering kinetics for Cu3Au, (Tc = 388 ° C), Ni3Mn (Tc = 500° C) Ni3Fe (Tc = 517°C) and Ni3Al (Tc = 1450 ° C), which all form the L12 superlattice, and these kinetics are correlated with diffusion data for the same alloys. Comparing different alloys, it is shown that for a fixed relaxation time for the establishment of order, the lower is the self-diffusivity, Ds, of the slowest-diffusing species, the higher the critical temperature, Tc, for the first appearance of order. Ni3A1, in particular, has an estimated Ds of about 5 orders of magnitude lower, on average, than the three other alloys. The implications of this inverse relation between Tc and Ds are discussed in relation to published models for diffusion in ordered alloys and ordering kinetics.

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