Physicochemical environment

Recently, epithermal gold deposits were divided into several types based on gangue minerals, and physicochemical environment of ore deposition (pH, H2S concentration of ore fluids). They are hot spring-type (Silberman, 1982 Berger, 1983a Berger and Eimon,... 

The geochemical implications of selenium contents of sulfides for the physicochemical environment of epithermal ore deposition will be discussed in section 1.4.4. 

Doi, S. (1972) Wall rock alteration at the Akeshi and Iwato mines with special reference to the physicochemical environment of its formation. Unpub. Masters Thesis, U. Tokyo. 

Sato, Takeo (1969) An estimation for physicochemical environments of formation of the Kuroko deposits based on their mineral paragenesis, Koshogakunote (Note on Economic Geology), 7, 1-16 (in Japanese). 

Shikazono, N. (1974a) Physicochemical environment and mechanism of volcanic hydrothermal ore deposition in Japan, with special reference to oxygen fugacity. J. Fac. Scl U. Tokyo, 19, 27-56. 

Kuroko deposits, which are strata-bound massive sulfide-sulfate deposits, are well-known because (1) many studies have been done and many papers (more than 1,(K)0) have been published since the work by Ohashi (1919), (2) original ore textures are preserved due to the absence of metamorphism, and (3) geological and physicochemical environments of ore deposition were well-elucidated. Summaries of previous studies on Kuroko deposits have been published in the 1970s and early 1980s (Ishihara, 1974 Ohmoto and Skinner, 1983). However, no summary written in English after the early 1980s has been published, although considerable works on ore deposits have been carried out. 

The six major proteins of milk, asl-, o s2-, and /c-casein, jS-lactoglobulin, and a-lactalbumin, contain at least one tryptophan residue [57], the fluorescence of which allows the monitoring of the structural modifications of proteins and their physicochemical environment during the coagulation processes. Emission fluorescence spectra of the protein tryptophanyl residues were recorded for the milk coagulation kinetics induced by... 

In Section II.3 we have seen that a specific chemical species existing in a given physicochemical environment is characterized by specific values of 7) and T2, and that this fact is important both in the implementation of imaging pulse sequences to obtain quantitative information and in the modification of the pulse sequences to image selectively one species and/or phase within the sample. While exploitation of relaxation time contrast is not likely to become a routine approach for chemical mapping in reactors, there will be niche applications in which it will continue to have use—three of these are identified below. The limitations of the approach derive from that fact that the relaxation times characterizing a system will not only be influenced by chemical composition but also by temperature and the proximity of the molecules to a solid surface or interface. The three case studies illustrated below in which relaxation time contrast has been used with considerable success are (i) an... 

Modification of an introduced cysteine is both time- and concentration-dependent. It is therefore possible to measure the rate of sulfhydryl modification by applying low concentrations of MTS over short periods of time. The rate of reaction depends on the following factors (1) the permeability of the access pathway to the substituted cysteine, (2) electrostatic potentials, (3) the degree of ionization of the thiol, and (4) local steric constraints (Karlin and Akabas, 1998). The rate constant provides important information about the physicochemical environment of the introduced cysteine residue, relative to other accessible residues within... 

The property of interest to characterize a surfactant or a mixture of surfactants is its hydrophilic-lipophilic tendency, which has been expressed in many different ways through a variety of concepts such as the hydrophiUc-lipophilic balance (HLB), the phase inversion temperature (PIT), the cohesive energy ratio (CER), the surfactant affinity difference (SAD) or the hydrophilic-lipophilic deviation (HLD) [1], which were found to be more or less satisfactory depending on the case. In the next section, the quantification of the effects of the different compounds involved in the formulation of surfactant-oil-water systems will be discussed in details to extract the concept of characteristic parameter of the surfactant, as a way to quantify its hydrophilic-lipophilic property independently of the nature of the physicochemical environment. 

A microorganism that is inoculated into a medium with a different composition than the previous culture medium or is transfered from one physicochemical environment (e.g. temperature, pH) to another does not grow immediately. Usually, a certain time is required to adjust to the new environment before growth can continue. This is called the... 

The observation that a specific chemical species existing in a given physicochemical environment is characterized by specific values of and 7 2 is important both in the implementation of imaging pulse sequences to obtain quantitative information and in the modification of the pulse sequences to image selectively one species and/or phase within the sample. 

In coal, copper shows an organic affinity different from the Mellor and Maley (14) series, and zinc appears to be completely associated with the inorganic matter. Copper in the physicochemical environment of coal deposition can be reduced to the univalent state (5). Univalent copper cannot be expected to behave like the bivalent metals. The ionic potential of univalent copper fits reasonably well into the organic affinity series (Figure la). 

The equilibrium nature of most natural inorganic systems allows one to predict the stable ionic or mineral components of an environment if its pH, redox potential, pressure, and temperature are defined. Conversely, the reconstruction of a fossil physicochemical environment is often possible by studying fossil mineral assemblages (I, 7). 

Small-scale interactions of DOM with the physicochemical environment affect the distribution and activity of microbial communities within systems and influence material fluxes by absorbing solar radiation (see Chapters 2 and 10), mediating the mobility of inorganic nutrients, enzymes, and other molecules (see Chapters 3, 5, 8, 11, and 19), and imposing a macromolecular architecture on the aqueous medium (see Chapters 12 and 18). 

Research by Soler-Serratosa et al. (1996) using combinations of thymol and benzaldehyde for root-knot and cyst nematode control on soybeans showed that both compounds exhibited wide spectrum nematicidal activity with Meloidogyne spp. and Dorylaimid nematodes being more sensitive than cyst nematode and nonparasitic nematodes (Soler-Serratosa et al., 1996). In addition to the direct toxicity of these compounds to nematodes, it was hyopothesized that stimulation of beneficial microflora by the compounds or their products, altered host response, and a deleterious physicochemical environment may all contribute to reduced gall formation (Soler-Seratosa et al., 1996). 

Urban, J.P. (2001) The role of the physicochemical environment in determining disc cell behavior. Biochem Soc Trans 30, 858-864... 

Each amino acid has distinct attributes such as size, hydrophobicity/hy-drophilicity, hydrogen bonding capacity, and conformational preferences that allow it to contribute to a protein fold. Attempts are being made to interpret the protein fold in terms of amino acid descriptors. Structural alignments are more accurate than sequence alignments, and the local physicochemical environment of every residue within each 3D structure is directly obtainable (e.g., AAindex at http //www. 

The physicochemical environment and ecologically important food-web interactions are not altered by the stressor, or are quickly restored. 

Synthesis of metal nanostructures with tunable properties (optical, magnetic, electronic, catalytic, etc.), in specific physicochemical environments, is today of great importance from a fundamental as well as an applied point of view. Since the physicochemical properties of nanostructures are strongly dependent not only on the size but also on the shape, controlling the architecture of metal nanoparticles... 

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