Specific Areas

NMR basic principles and progress specialised monograph giving detailed descriptions of specific areas of solid state NMR. 

The central idea underlying measurements of the area of powders with high surface areas is relatively simple. Adsorb a close-packed monolayer on the surface and measure the number A of these molecules adsorbed per unit mass of the material (usually per gram). If the specific area occupied by each molecule is A then the... 

Over the years, as mentioned, I followed the practice that, whenever in a specific area of my research I felt that I had substantially achieved my goals and that it was time to consider shifting my emphasis elsewhere, I wrote (or edited) a book or comprehensive review of the field. My books are listed in the Appendix for interested readers who want to obtain more information or details, as well as relevant literature references. 

With the results of the preceding section thus salvaged, let us look in more detail at the specific areas of discrepancy between the perfectly flexible model... 

Adsorbent Pore diameter, nm Particle density, g/cm Specific area, mVg Apphcations... 

Amorphous Adsorbents. The amorphous adsorbents (siUca gel, activated alumina, and activated carbon) typically have specific areas in the 200—1000-m /g range, but for some activated carbons much higher values have been achieved (- 1500 /g). The difficulty is that these very high area... 

Desiccants. A soHd desiccant is simply an adsorbent which has a high affinity and capacity for adsorption of moisture so that it can be used for selective adsorption of moisture from a gas (or Hquid) stream. The main requkements for an efficient desiccant are therefore a highly polar surface and a high specific area (small pores). The most widely used desiccants (qv) are siHca gel, activated alumina, and the aluminum rich zeoHtes (4A or 13X). The equiHbrium adsorption isotherms for moisture on these materials have characteristically different shapes (Fig. 3), making them suitable for different appHcations. 

The concentration of alkaloids, as well as the specific area of occurrence or localization within the plant or animal, can vary enormously. Thus the amount of nicotine [54-11-5] (21), C2QH24N2, apparentiy synthesized ia the roots of various species of JSHcotiana and subsequentiy translocated to the leaves varies with soil conditions, moisture, extent of cultivation, season of harvest, etc and may be as high as 8% of the dry leaf, whereas the amount of morphine (2, R = H) ia cerebrospiaal duid is of the order of 2 to 339 fmol/mL (23). 

There are large concentrations of proven reserves ia specific areas of the globe such as the Middle East, North America, and the Confederation of Independent States. Thus the future of natural gas, worldwide, is dependent on the flow of natural gas across international boundaries on a long-term basis. This future is also dependent on the maintenance of an economic balance between the price of oil and the price of natural gas. 

Ia the 1990s robotics guided by artificial iateUigeace are expected to play a role comparable to that of electronics in the 1940s and 1950s (6). Expert systems, which are knowledge-based systems that can effectively represent and apply factual knowledge in specific areas of human expertise, seem ideaUy suited to robot supervision. 

Shade Stains. These stains are usually applied after the sealer or first topcoat and are typically sprayed on specific areas to compensate for uneven color distribution during the initial finishing process. For instance, perhaps the gla2e was wiped too clean on an edge. Rather than going back to restain or gla2e that small area, the finisher can spray a small amount of this shade stain on the desired area and achieve the same result in a fraction of the time. 

Pitting corrosion may occur generaHy over an entire aHoy surface or be localized in a specific area. The latter is the more serious circumstance. Such attack occurs usuaHy at surfaces on which incomplete protective films exist or at external surface contaminants such as dirt. PotentiaHy serious types of corrosion that have clearly defined causes include stress—corrosion cracking, deaHoying, and corrosion fatigue (27—34). 

Palladium and Palladium Alloys. Palladium is used in telephone equipment and in electronics appHcations as a substitute for gold in specific areas. Palladium is plated from ammoniacal and acid baths available along with chelated variations as proprietary processes. One typical alkaline bath uses 8 g/L diammine-dinitropalladium, 100 g/L ammonium nitrate, and 10 g/L sodium nitrite. The pH is adjusted to 9—10 using ammonium hydroxide, and the bath is operated at 100 A/m at 50° C. If ammonium sulfamate, 100 g/L, is used in some baths to replace the nitrate and sodium nitrite salts, the bath is mn at lower temperature, 25—35°C, and a pH of 7.5—8.5. A palladium—nickel alloy, 75% Pd, is plated from a bath having 6 g/L palladium from the same salt, 3 g/L nickel from nickel sulfamate concentrate, and 90 g/L ammonium hydroxide. The bath is operated at 20—40°C with 50-100 A/m/... 

The confinement of the cracks to a specific area of the cooler suggests that condensate from atmospheric moisture initially formed in this area and dissolved a corrodent from the atmosphere such as ammonia, sulfur dioxide, or oxides of nitrogen. Since the previous cooler had been in service for 20 years, it is conjectured that the rapid failure of this exchanger was due principally to very high bending stresses, which may have been induced during construction of the cooler. 

Examination of the microstructure of the cavitated surface will commonly disclose evidence of deformation such as twins (Neumann hands) in carbon steel and general cold working in other metals (Case History 12.6). Damage from cavitation can be differentiated from attack by a strong mineral acid, which can produce a similar surface appearance, by observing the highly specific areas of attack characteristic of cavitation. Acid attack is typically general in its extent (Case History 12.6). 

The pump has experienced graphitic corrosion. Figures 17.10, 17.12, and 17.14 illustrate typical appearances of graphitically corroded cast iron. In addition, cavitation damage (see Chap. 12) has produced severe metal loss in specific areas (see Fig. 17.13). The soft, friable corrosion products produced by graphitic corrosion are susceptible to cavitation damage at relatively low levels of cavitation intensity. 

Distributed Control System (DCS) A system that divides process control functions into specific areas interconnected by communications (normally data highways) to form a single entity. It is characterized by digital controllers, typically administered by central operation interfaces and intermittent scanning of the data highway. 

Evidence is demonstrated that the company is active to some degree for the specific area in question. This accounts for instances of partial compliance however, the system or documentation is not complete enough to avoid noncompliance in the near term. 

Describe the impact of future visibility degradation on your area (e g, on specific areas of scenic attraction). 

Improvement of equipment effectiveness. This should start with a detailed design review of the plant machinery. A performance analysis of the plant could point to a specific area known to have problems (i.e., section of plant) must be selected and focused on, project teams should be formed and assigned to each train. An analysis should be conducted that address the following ... 

A comparison of the various post-ionization techniques electron-gas bombardment, resonant and nonresonant laser ionization, etc. While some of the numbers are outdated, the relative capabilities of these methods have remained the same. This is a well-written review article that reiterates the specific areas where post-ionization has advantages over SIMS. 

Pre-employment medical for selection and establishment of base levels Working conditions in specific areas Employees routine medicals, exposure profiles Biological monitoring where appropriate... 

What to do if they are unable to go to the nominated assembly point. (Different assembly points may be appropriate for different incidents, e.g. a fire in a specific area, a potential explosion or a spillage.)... 

The pulse-echo and resonance impedance techniques are capable of determining which layer contains a disbond, given an appropriate standard to compare against. Inspection standards are bond assemblies made to simulate specific areas of a part with disbonds purposefully placed in them. By comparing the signal response of a suspected void to that of a known disbond in the standard, the... 

At the end of this chapter you will find a summary of the topics discussed in this volume. This will help you to focus on specific areas of reading that are most useful to you. There is also a list of recommended resources, including Web sites. 

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