Physical and chemical processes

The various chemical and physical processes that play a role ia the deterioration of art objects are not restricted to the present, even though the contemporary environment has contributed significantly to the rate of decay. Revered masterpieces have lost splendor throughout the ages. Indeed, from textual evidence, it is known how artists ia the Renaissance restored works of art from Classical times. These restorers of past centuries attempted to return the object to its original appearance. The fallacy of that idea Hes ia the fact that they could not know the exact original appearance of the work, ie, immediately after its creation therefore, they restored the object according to their subjective opinions. 

Eoamable compositions in which the pressure within the cells is increased relative to that of the surroundings have generally been called expandable formulations. Both chemical and physical processes are used to stabilize plastic foams from expandable formulations. There is no single name for the group of cellular plastics produced by the decompression processes. The various operations used to make cellular plastics by this principle are extmsion, injection mol ding, and compression molding. Either physical or chemical methods may be used to stabilize products of the decompression process. 

Landfarming Landfarming is a waste-disposal method in which the biological, chemical, and physical processes that occur in the surface of the soil are used to treat biodegradable industrial wastes. Wastes to be treated are either apphed on top of the laud which has... 

Effects of transport processes cannot be ignored in investigations aimed at more fundamental aspects of kinetics and catalysis. The interaction of chemical and physical processes was noticed a long time ago. M. V. Lomonosov mentioned in 1745 ... 

Nonferrous metallurgy is as varied as the ores and finished products. Almost every thermal, chemical, and physical process known to engineers is in use. The general classification scheme that follows gives an understanding of the emissions and control systems aluminum (primary and secondary), beryllium, copper (primary and secondary), lead (primary and secondary), mercury, zinc, alloys of nonferrous metals (primary and secondary), and other nonferrous metals. 

Capp, B. and Seebold, J. 1991. Detonation Experiments m an 18-mch Pipe. Paper presented at the 1991 Annual AlChE Meeting session of Fundamental Chemical and Physical Processes m Combustion and Incineration 1. Los Angeles, CA, November 17-22. American Institute of Chemical Engineers, New York, NY. 

Catalysis has been employed in science to designate a substance which by its mere presence facilitates or enhances the rate of chemical reactions. As such it was a cloak tor ignorance. Wlien the states of an over-all catalytic process can be described in terms of a well-defined succession of chemical and physical processes the details of which are well understood or ai e quite plausible, then the necessity for employing such a word as catalysis to mask our ignorance no longer exists.. . ... 

This review addresses the issues of the chemical and physical processes whereby inorganic anions and cations are selectively retained by or passed through cell membranes. The channel and carrier mechanisms of membranes permeation are treated by means of model systems. The models are the planar lipid bilayer for the cell membrane, Gramicidin for the channel mechanism, and Valinomycin for the carrier mechanism. 

Unlike the chemistry of simple mixtures of small numbers of reactants as observed in the laboratory, the chemistry of the atmosphere involves complex interactions of large numbers of species. However, several key aspects of these interactions have been identified that account for major observable properties of the atmospheric chemical system. It is convenient to separate the description into gas phase and condensed phase interactions, not the least because different chemical and physical processes are involved in these two cases. 

The curing of polyurethane paints is a complex chemical and physical process therefore a mathematical model may be a valuable tool to describe the process and manage the data. 

Akaku, K., Reed, M.H., Yagi, M., Kai, K. and Yasuda, Y. (1991) Chemical and physical processes occurring in Fushime geothermal system, Kyushu, Japan. Geochem. J., 25, 315-333. 

Fig. 5.1. Chemical and physical processes that lead to de-excitation of excited atoms in gaseous phase (taken from [28])...

In isotope dilution inductively coupled plasma-mass spectrometry (ID-ICP-MS) the spike, the unspiked and a spiked sample are measured by ICP-MS in order to determine the isotope ratio. Using this technique, more precise and accurate results can be obtained than by using a calibration graph or by standard addition. This is due to elimination of various systematic errors. Isotopes behave identically in most chemical and physical processes. Signal suppression and enhancement due to the matrix in ICP-MS affects both isotopes equally. The same holds for most long-term instrumental fluctuations and drift. Accuracy and precision obtained with ID-ICP-QMS are better than with other ICP-QMS calibration... 

Degree to which each chemical and physical process effects dissipation... 

In the version of evolutionary theory popularised by Dawkins (1976), the fundamental unit of life is a gene, a conceptual abstraction clothed in the biochemistry of the nucleic acid DNA. The purpose, or telos, of this gene is replication - to make copies of itself - copies which because of random chemical and physical processes maybe more or less accurate. The particular chemical structure of DNA provides a mechanism whereby such faithful copying can readily occur - as James Watson and Francis Crick pointed out... 

The common properties of Titan and our Earth have led to great scientific interest in this Saturnian satellite, which can be considered as a type of extraterrestrial laboratory in which a series of chemical and physical processes occur which are similar to those involved in chemical evolution on the primeval Earth. 

This argument, however, ignores an essential aspect of the second law, which is valid only for closed systems, i.e., systems for which neither matter nor energy can be exchanged with the environment. The chemical and physical processes which led to biogenesis on the primeval Earth did not take placed in closed systems, but in open ones. Matter and energy exchange were in fact essential for the successful execution of reaction sequences, as for example in the formation and synthesis of biomonomers. 

Shainberg I. Chemical and mineralogical components of crusting. In Soil Crusting, Chemical and Physical Processes, M.E. Sumner, B.A. Stewart, eds. Advances in Soil Science, Boca Raton Lewis Publishers, 1990. 

When we speak of the dissolution of an estate, we are applying the common definition and we know that the estate will be broken up into parts. In chemistry, when we discuss the ease of solute dissolution, we are implying a full range of chemical and physical processes that take place when a solute dissolves. 

The basic light initiated reactions used in the diverse applications of photopolymer technology can be classified into 5 categories based on the chemical and physical processes utilized. 

Very recent historians of alchemy, in fact, now see the spiritual alchemy hypothesis of the occult revival as historically inaccurate. They support the position held by early twentieth-century occult alchemists and historians that alchemy, in addition to its spiritual dimensions, was truly a material practice (see, for example, Principe and Newman 2001, and Newman and Principe 2002). Moreover, they deny that the chemical and physical processes in alchemical writings were simply code for entirely spiritual processes and reject the notion that alchemists had been able to transmute matter by an act of will. 

Processes in nature correspond generally only in a first approximation to what is postulated in the principles of dating methods. An exception is radioactive decay which is almost independent of variations in the environmental conditions, since energy differences are involved which are large compared to differences of thermal excitation in the environment. This is in contrast to chemical and physical processes which do depend on environmental parameters such as temperature. An example showing... 

The studies described in the preceding two sections have identified several processes that affect the dynamic behavior of three-way catalysts. Further studies are required to identify all of the chemical and physical processes that influence the behavior of these catalysts under cycled air-fuel ratio conditions. The approaches used in future studies should include (1) direct measurement of dynamic responses, (2) mathematical analysis of experimental data, and (3) formulation and validation of mathematical models of dynamic converter operation. 

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