Deterioration processes

The very high powers of magnification afforded by the electron microscope, either scanning electron microscopy (sem) or scanning transmission electron microscopy (stem), are used for identification of items such as wood species, in technological studies of ancient metals or ceramics, and especially in the study of deterioration processes taking place in various types of art objects. 

No conservation treatment can completely undo damages to art objects. However, damage can often be prevented (171—173). Many deterioration processes are dependent upon environmental conditions. 

Stationary monitoring networks are also operated to determine the impact of new sources of emissions. As part of the environmental impact statement and Prevention of Significant Deterioration processes, the projected impact of a new source on existing air quality must be assessed. Air quality monitoring is one means of making this type of assessment. A monitoring network... 

The sensitivity of Magnetic Resonance (MR) to the local concentration, molecular dynamics and molecular environment of these nuclei make it well suited for the study of deterioration processes in concrete materials. Hydrogen (water), lithium, sodium, chlorine and potassium are all MR sensitive nuclei and play an important role in cement chemistry. The ability of MRI to spatially resolve and non-destructively examine test samples as a function of treatment or exposure has the potential to provide new insight to better understand deterioration mechanisms and mass transport properties of concrete materials. 

As membrane deteriorations can be seen in case of performance degradations or changes in membrane structure, we have investigated into these two aspects. Information about the relation between membrane characteristics and deterioration processes is useful for trouble-shooting. Even if operation records showed no implication of deteriorating process of a membrane, the analysis of the deteriorated membrane will reveal its own history. 

Zuo, L. et al., 2D-IR correlation analysis of deteriorative process of traditional Chinese medicine Quing Kai Ling injection, J. Pharm. Biomed. Appl, 30, 1491, 2003. 

Mechanisms regulating deterioration processes in the burial state are still rather unknown and little research has been done on the consequences of long-term corrosion on the stability of the objects. Nevertheless, some studies have been performed on metal artifacts, seeking to characterize the surface layer as well as establish a relationship between the composition of the corrosion products and the environment where they formed. 

The common thread in these water deterioration processes is their being cases of intermixing of natural waters of different qualities or mixing of uncontaminated water with contaminated effluents. Hence the need (1) to be familiar with the methodology of mixing identification and reconstruction of the properties of the involved end members (section 6.7) and (2) the establishment of initial databases (section 18.3). 

Barrow wondered about the deteriorative processes that made lamination necessary. There was no reason to suppose that degradation was stopped by lamination. He concluded that the acidic nature of the paper itself was the primary cause of the degradation and then began to look for ways to combat the problem. By the end of 1945, he had developed his deacidification process in which solutions of calcium hydroxide and calcium and/or magnesium bicarbonate are used to neutralize acidity and leave within the paper an alkaline material to combat acidity from future degradation and pollution. 

Matched sets of folding endurance and tear resistance test specimens were prepared from each paper to be aged at several temperatures. Aging was done in forced circulation ovens that were supplied with air having a dewpoint of 53°F. At intervals, sets of test specimens were removed from the oven and tested to monitor the deterioration process. 

This chapter is an overview of the wide variety of archaeological studies conducted by chemists. From the earliest stone artifacts to the artistic manuscripts and textiles of the more recent past, the studies presented in this volume show the wide range of materials that have been studied by chemical techniques. The field keeps expanding as chemists help provide information valuable in the interpretation of archaeological sites and artifacts. Besides helping to detect fraudulent artifacts and artistic objects in museum collections, chemists have studied the physicochemical deterioration processes that destroy the monuments and objects of the past. Thus, the role of chemists is more than just discovery of the past it includes investigation that may help preserve the artifacts for future generations to enjoy and study. 

Lifetime predictions of polymeric products can be performed in at least two principally different ways. The preferred method is to reveal the underlying chemical and physical changes of the material in the real-life situation. Expected lifetimes are typically 10-100 years, which imply the use of accelerated testing to reveal the kinetics of the deterioration processes. Furthermore, the kinetics has to be expressed in a convenient mathematical language of physical/chemical relevance to permit extrapolation to the real-life conditions. In some instances, even though the basic mechanisms are known, the data available are not sufficient to express the results in equations with reliably determined physical/chemical parameters. In such cases, a semi-empirical approach may be very useful. The other approach, which may be referred to as empirical, uses data obtained by accelerated testing typically at several elevated temperatures and establishes a temperatures trend of the shift factor. The extrapolation to service conditions is based on the actual parameters in the shift function (e.g. the Arrhenius equation) obtained from the accelerated test data. The validity of such extrapolation needs to be checked by independent measurements. One possible method is to test objects that have been in service for many years and to assess their remaining lifetime. 

Process capability is expressed in either the short-term or the long-term. Recall that the Kiosk Configurators determined capability by collecting data from one short period of time. Therefore, they can expect 0.6 percent of customers to have wait times longer than 120 seconds in the short term over the long term, however, they can expect the process to shift and drift, thereby deteriorating process capability. 

The net effect of the entire deterioration process is to alter physical and chemical properties so that the weathering stone becomes even more susceptible to atmospheric attack. 

Seeds are orthodox and deteriorative processes during storage are reported as dependent on their physical state and on solid/water interactions (Walters, 1998). 

Obtained results show that different phases of fruit (water-soluble compounds and insoluble product matrix) contribute to different extent to the quality preservation of dried fruit as a function of moisture content. At moisture levels higher than 3%, plasticization of the water-soluble phase can promote crystallization or deteriorative processes. Nevertheless, no relevant changes in product texture (mechanical response) occur until the moisture level reaches 12%. This observation is in agreement with the great contribution of fhe insoluble producf mafrix phase (less water-plasticizable) fo fhe mechanical properfies. 

In summary, the main cause for masonry deterioration is the presence of water in it. A dry wall will not effloresce, the salts contained in it will not be able to recrystallize and other deterioration processes such as freeze-thaw will also be avoided. 

Finally, the surfaces of the cores are examined both optically and by secondary electron microscopy to determine the extent of microstructural changes that are occuring due to atmospheric exposure. Energy dispersive analysis of x-rays (EDAX) also serves to detect atmospheric particles which have deposited onto the core surface. All this information can then be used to at least qualitatively identify deterioration processes that may be occuring. 

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