External processing environment

Chapter 14 discusses the external processing environment, which is the laboratory or production environment in which the substrates, fixtures, vaporization sources, etc. are... 

Contamination, external environment-related (contamination control) Contamination brought in from the external processing environment. Example Particulate contamination from dust. 

External processing environment (PVD technology) The processing environment external to the deposition system in which processes such as cleaning, racking, and un-racking take place. 

Process controls and instrumentation only provide feedback for conditions within the process system. They do not report or control conditions outside the assumed process integrity limits. Fire and gas detection systems supplement process information systems with instrumentation that is located external to the process to warn of conditions that could be considered harmful if found outside the normal process environment. Fire and gas detection systems may be used to confirm the readings of major process releases or to report conditions that process instrumentation may not adequately report or be unable to report (i.e., minor process releases). 

The detoxification and excretion of xenobiotics (i.e., foreign compounds, including diet-derived allelochemicals) involve a suite of highly complex processes that allow an organism to respond to its internal and external chemical environments. Suchmetabolic resistance involves the biochemical transformation... 

The integrins comprise a family of cell-surface proteins that are involved in adhesion, a process vital for many processes, such as anchorage, migration, growth and differentiation. Cells may adhere to other cells (cell-cell adhesion) or may interact with soluble molecules that constitute the extracellular matrix (cell-extracellular matrix). The integrins are linked to elements of the cytoskeleton, and so they provide a bridge between the external cellular environment and intracellular activation processes. 

This section examines some experimental evidence for the transient behavior of individual cells evaluated on single-cell test stands and stacks contained within full systems. Results from models developed to help understand some of the detailed physical effects that influence cell performance are also examined. The goal is to introduce, albeit in brief, some of the principle dynamic characteristics of single cell and full stack performances. Single cell studies are important since they isolate the cell in a well understood and controlled environment thereby removing the effects of other external processes (e g., reforming) which may have their own transient behavior that affects cell operation (e g., controlling cell input fuel composition). Such... 

When proteins precipitate with heating, it is because the protein turns inside-out, exposing many of the lipophilic amino add residues (residues previously facing the inner core of the protein) to the external aqueous environment. The process of turning inside-out is called denaturation. The lipophilic amino acids... 

Recoils can interfere with ordinary chemical processing. If a parent nuclide is adsorbed on a surfece, such as a bead of ion-exchange resin or the surface of a container, the recoil can embed deep in the support material and not be in equilibrium with the external chemical environment... 

Source factories also aim at producing low costs. However, here the local management is endowed with more responsibility to organize and improve internal and external processes. Furthermore, the strategic importance of the produced goods is superior to those of the offshore factory, and their integration into their environment is more developed. 

By moving the measurement from the well-controlled laboratory to the process environment, the influence of external process variables such as p, T, and flow turbulence will affect the measurements. When vibrational spectra are measured on- or in-line for process analytical and control purposes, the performance variations influence the shape of the spectra in a non-linear manner. Smilde et al. [81] have assessed the influence of these temperature-induced spectral variations on the predictive ability of multivariate calibration models. 

On the basis of direct measurements on stainless steel, alloy 600, and low-alloy steel-water systems at 288°C, it is known that the electrode potential and pH conditions at the tip of a crevice or crack can differ markedly from those at the exposed crevice or crack mouth [1,70-74], These variations are understood and have been extensively reviewed [45,75-77] in terms of the thermodynamics of various metal oxidation and metal cation hydrolysis reactions and how they are influenced by the reduction processes of e.g., dissolved oxygen at the crack mouth. From a practical viewpoint, the corrosion potential which exists at the deaerated crack tip is controlled primarily by pH, but it can be defined [1] in terms of the measurable dissolved oxygen content in the external water environment (Fig. 9) (or preferably by the measurable corrosion potential of the external system) and the purity of the external water. 

Thermod5mamics studies a system, i.e., a body or group of bodies capable of changing imder the influence of physical or chemical processes. Everything surroimding the system forms the external medium (environment). By a body they usually understand any substance having a certain volume and characterized by some physical properties. Thermod5mamic... 

In some cases, the effect of the processing environment can be minimized by integrating the external processing into the processing line. An example is the use of washing and drying modules coimected to the in-line deposition system used to coat flat-glass mirrors. 

In order to have a reproducible PVD process it is important to have a good vacuum environment. Contamination can originate in the deposition system itself and it is important that this source of contamination be considered as well as contamination from the external processing enviromnent and from the as-received material. 

Supervision of the external process [44] permits intensive use of routines while relying on planning and guidance obtained from the affordance within the environment. It is only in situations where problems arise and routine processes are blocked that cognitive processes are invoked in that case cognition has to be used more intensively and that intensity must also be controlled so that it produces results that are useful before the deadline for the process, which continues to evolve [45]. 

Selectivity in FIA is often better than that for conventional methods of analysis. In many cases this is due to the kinetic nature of the measurement process, in which potential interferents may react more slowly than the analyte. Contamination from external sources also is less of a problem since reagents are stored in closed reservoirs and are pumped through a system of transport tubing that, except for waste lines, is closed to the environment. 

---