GEOSURF: a computer program for modeling adsorption on mineral surfaces from aqueous solution

1998 ◽  
Vol 24 (9) ◽  
pp. 853-873 ◽  
Author(s):  
Nita Sahai ◽  
Dimitri A. Sverjensky
Keyword(s):  
Aqueous Solution ◽  
Computer Program ◽  
Mineral Surfaces

The adsorption of progesterone onto mineral surfaces imaged with high-resolution atomic force microscopy

2008 ◽  
Vol 72 (1) ◽  
pp. 419-424
Author(s):  
B. Goritschnig ◽  
K. R. Hallam ◽  
T. McMaster ◽  
V. Ragnarsdottir
Keyword(s):  
Aqueous Solution ◽  
Atomic Force Microscopy ◽  
High Resolution ◽  
Uv Light ◽  
Pyrolytic Graphite ◽  
Ultra Violet ◽  
Mineral Surfaces ◽  
Force Microscopy ◽  
Atomic Force

AbstractAtomic force microscopy (AFM) has been used to monitor the appearance and behaviour of the hormone progesterone on mineral surfaces, including mica and highly oriented pyrolytic graphite (HOPG). Different solvents have been used resulting in various features on the two substrates. After the application of 254 nm ultra-violet (UV) light, changes in structure of the adsorbed hormone have been observed. To understand the reactions at the progesterone-mica interface in aqueous solution, adsorption has been studied in situ with AFM.

Complexes of Cu(II) with D-aldonic and D-alduronic acids in aqueous solution

1992 ◽  
Vol 70 (7) ◽  
pp. 2053-2057 ◽  
Author(s):  
Graciela M. Escandar ◽  
Luis F. Sala
Keyword(s):  
Aqueous Solution ◽  
Ionic Strength ◽  
Computer Program ◽  
Quantitative Study ◽  
Hydrogen Ion ◽  
Complex Species ◽  
Ion Concentrations ◽  
Aldonic Acid ◽  
Potentiometric Measurements ◽  
Equilibrium Data

A quantitative study of the equilibria involved in the interaction of Cu(II) ion with D-glucoheptonic, D-gluconic, D-galactonic, D-ribonic, D-glucuronic, and D-galacturonic acids in aqueous medium has been carried out by means of potentiometric measurements of hydrogen ion concentrations at a constant temperature of 20 °C and an ionic strength of 0.10 (NaNO3). The equilibrium data were processed with the FORTRAN computer program BEST. It was found that Cu(II) interacts with D-aldonic acids to form 1:1, 2:2, and 1:2 (M/L) complexes. The copper(II) complexes with D-galacturonic and D-glucuronic acids are considerably weaker than those of D-aldonic acid. Possible structures of the complex species formed are discussed.

A general computer program for the extended plate overlap algorithm

1978 ◽  
Vol 48 ◽  
pp. 287-293 ◽  
Author(s):  
Chr. de Vegt ◽  
E. Ebner ◽  
K. von der Heide
Keyword(s):  
Computer Program ◽  
Simultaneous Determination ◽  
General Computer Program ◽  
General Computer

In contrast to the adjustment of single plates a block adjustment is a simultaneous determination of all unknowns associated with many overlapping plates (star positions and plate constants etc. ) by one large adjustment. This plate overlap technique was introduced by Eichhorn and reviewed by Googe et. al. The author now has developed a set of computer programmes which allows the adjustment of any set of contemporaneous overlapping plates. There is in principle no limit for the number of plates, the number of stars, the number of individual plate constants for each plate, and for the overlapping factor.

Structures Formed by Cryoprotective Agents Used in Freezc-Etching

1971 ◽  
Vol 29 ◽  
pp. 448-449
Author(s):  
G. G. Cocks ◽  
C. E. Cluthe
Keyword(s):  
Aqueous Solution ◽  
Polyethylene Oxide ◽  
Liquid Nitrogen Temperature ◽  
Ice Crystals ◽  
Etching Technique ◽  
Structural Constituent ◽  
Cryoprotective Agents ◽  
Quick Freezing ◽  
Freeze Etching ◽  
Fractured Surface

The freeze etching technique is potentially useful for examining dilute solutions or suspensions of macromolecular materials. Quick freezing of aqueous solutions in Freon or propane at or near liquid nitrogen temperature produces relatively large ice crystals and these crystals may damage the structures to be examined. Cryoprotective agents may reduce damage to the specimem, hut their use often results in the formation of a different set of specimem artifacts.In a study of the structure of polyethylene oxide gels glycerol and sucrose were used as cryoprotective agents. The experiments reported here show some of the structures which can appear when these cryoprotective agents are used.Figure 1 shows a fractured surface of a frozen 25% aqueous solution of sucrose. The branches of dendritic ice crystals surrounded hy ice-sucrose eutectic can be seen. When this fractured surface is etched the ice in the dendrites sublimes giving the type of structure shown in Figure 2. The ice-sucrose eutectic etches much more slowly. It is the smooth continuous structural constituent surrounding the branches of the dendrites.

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