Physico-chemical weathering reactions as a formulary for time-lapsing ageing tests

In the process of improving the knowledge of the hydrogeological potential of weathered zones in crystalline rocks and compounds that can behave as aquifers, this article is performed whose area of study is located east of the metropolitan area of Bucaramanga, Santander Massif consists of two main lithological units; the Neis of Bucaramanga and Santander Group plutonic (diorite, granodiorite-tonalite gray quartz monzonite and monzogranite). These rocks have undergone brittle deformation, physico-chemical weathering mainly influenced by the tropical atmosphere of the area also are jointed and fractured creating conditions that facilitate the flow of water and in turn be optimized weathering processes in the region. He appealed to the identification and location of field weathering profiles made a detailed study of outcrops, presenting a thickness of 90.4 m for the profile of the Gneisic rock weathering and 68.5 m for the profile of granodiorite rock, made up 6 steps weathering of which samples each were taken and carry out macroscopic analysis, petrographic and geochemical using thin films, determining the percentage of porosity, humidity, dry unit weight, X-ray fluorescence, electron microscopy Sweeping and Grading; base characterizing weathering profiles and properties, highlighting the potential hydrogeological found in the Range II: Slightly weathered rock and interval V: Completely weathered rock profile of granodiorite rock and Rock Gneisic profile, the interval III : Moderately weathered rock and the range V: Completely weathered rock, since these stages of weathering, moisture peaks present, regular micro fractures and high porosities.

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ASSESSING THE EFFECT OF ARMOURSTONE SHAPE AND WEAR

Coastal Engineering Proceedings ◽

10.9753/icce.v21.170 ◽

1988 ◽

Vol 1 (21) ◽

pp. 170 ◽

Cited By ~ 1

Author(s):

John-Paul Latham ◽

Alan B. Poole

Keyword(s):

Chemical Weathering ◽

Shape Change ◽

Block Size ◽

New Techniques ◽

Wear Factor ◽

Mill Time ◽

Design Concepts ◽

Initial Block ◽

Physico Chemical ◽

Rapid Changes

Impacts, abrasion and physico-chemical weathering which sometimes result in rapid changes of armour shape and size can have disastrous consequences for armour stability. This paper draws together the background ideas and some new techniques which have been developed to tackle the prediction of weight loss and shape change of rock armourstone during the life of a coastal structure. The framework proposed is to measure separately the wear resisting material properties of a rock type using a tumbling mill simulation of prototype block degradation. Time on the structure is then related to mill time by a factor which accounts for initial block size and the site specific environmental conditions. A field site in Scotland is used to demonstrate the new image analysis methods for measuring rounding of prototype blocks. The shape analysis results can also be used to calibrate the equivalent wear factor for conditions at that site. Discussion of this framework is extended to dynamically stable design concepts where abrasion losses are faster. Preliminary flume testing in collaboration with H. R. Wallingford indicates that losses in stability due to rounding could be considerable.

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Decoration of specific sites on freeze-fractured membranes

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100081565 ◽

1978 ◽

Vol 36 (2) ◽

pp. 140-141

Author(s):

H. Gross ◽

H. Moor

Keyword(s):

Pure Water ◽

Freeze Fracture ◽

Chemical Properties ◽

Surface Forces ◽

Sulfate Pentahydrate ◽

Copper Sulfate Pentahydrate ◽

Physico Chemical ◽

Water Of Hydration ◽

Small Container ◽

Binding Forces

Fracturing under ultrahigh vacuum (UHV, p ≤ 10-9 Torr) produces membrane fracture faces devoid of contamination. Such clean surfaces are a prerequisite foe studies of interactions between condensing molecules is possible and surface forces are unequally distributed, the condensate will accumulate at places with high binding forces; crystallites will arise which may be useful a probes for surface sites with specific physico-chemical properties. Specific “decoration” with crystallites can be achieved nby exposing membrane fracture faces to water vopour. A device was developed which enables the production of pure water vapour and the controlled variation of its partial pressure in an UHV freeze-fracture apparatus (Fig.1a). Under vaccum (≤ 10-3 Torr), small container filled with copper-sulfate-pentahydrate is heated with a heating coil, with the temperature controlled by means of a thermocouple. The water of hydration thereby released enters a storage vessel.

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Activation of cytochrome c to a peroxidase compound I-type intermediate by H2O2: relevance to redox signalling in apoptosis

Biochemical Society Symposium ◽

10.1042/bss0710097 ◽

2004 ◽

Vol 71 ◽

pp. 97-106 ◽

Cited By ~ 10

Author(s):

Mark Burkitt ◽

Clare Jones ◽

Andrew Lawrence ◽

Peter Wardman

Keyword(s):

Cytochrome C ◽

Hydroxyl Radical ◽

Redox Regulation ◽

Chemotherapeutic Agents ◽

Tyrosyl Radical ◽

Compound I ◽

Definitive Evidence ◽

Enhanced Production ◽

Physico Chemical

The release of cytochrome c from mitochondria during apoptosis results in the enhanced production of superoxide radicals, which are converted to H2O2 by Mn-superoxide dismutase. We have been concerned with the role of cytochrome c/H2O2 in the induction of oxidative stress during apoptosis. Our initial studies showed that cytochrome c is a potent catalyst of 2′,7′-dichlorofluorescin oxidation, thereby explaining the increased rate of production of the fluorophore 2′,7′-dichlorofluorescein in apoptotic cells. Although it has been speculated that the oxidizing species may be a ferryl-haem intermediate, no definitive evidence for the formation of such a species has been reported. Alternatively, it is possible that the hydroxyl radical may be generated, as seen in the reaction of certain iron chelates with H2O2. By examining the effects of radical scavengers on 2′,7′-dichlorofluorescin oxidation by cytochrome c/H2O2, together with complementary EPR studies, we have demonstrated that the hydroxyl radical is not generated. Our findings point, instead, to the formation of a peroxidase compound I species, with one oxidizing equivalent present as an oxo-ferryl haem intermediate and the other as the tyrosyl radical identified by Barr and colleagues [Barr, Gunther, Deterding, Tomer and Mason (1996) J. Biol. Chem. 271, 15498-15503]. Studies with spin traps indicated that the oxo-ferryl haem is the active oxidant. These findings provide a physico-chemical basis for the redox changes that occur during apoptosis. Excessive changes (possibly catalysed by cytochrome c) may have implications for the redox regulation of cell death, including the sensitivity of tumour cells to chemotherapeutic agents.

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