Present day

The war itself also drove the development of improved and miniaturised electronic components for creating oscillators and amplifiers and, ultimately, semiconductors, which made practical the electronic systems needed in portable eddy current test instruments. The refinement of those systems continues to the present day and advances continue to be triggered by performance improvements of components and systems. In the same way that today s pocket calculator outperforms the large, hot room full of intercormected thermionic valves that I first saw in the 50 s, so it is with eddy current instrumentation. Today s handheld eddy current inspection instrument is a powerful tool which has the capability needed in a crack detector, corrosion detector, metal sorter, conductivity meter, coating thickness meter and so on. 

For a recent critical evaluation of situations where current DFT approaches experience difficulties, see Davidson E R 1998 How robust is present-day DFT ... 

Present day techniques for structure determination in carbohydrate chemistry are sub stantially the same as those for any other type of compound The full range of modern instrumental methods including mass spectrometry and infrared and nuclear magnetic resonance spectroscopy is brought to bear on the problem If the unknown substance is crystalline X ray diffraction can provide precise structural information that m the best cases IS equivalent to taking a three dimensional photograph of the molecule... 

The suggestion frequentiy is made that substitution of organic fertilizers, namely manures and composts, for chemical fertilizers would be of ecological benefit. The reaUty is, however, that the supply and logistics of such materials could never be adequate for the present-day level of agriculture. Furthermore, iatensive appHcation of such materials to the soil would itself present ecological problems, such as mn-off pollution and steady buildup of toxic heavy metals. 

Aerosolized steroids clearly play an important role in the present-day management of asthma (87). They are reasonably safe and work best when taken prophylacticaHy. Patient compliance, however, remains a significant problem. In part this problem is typical of any aerosolized agent. But in the case of steroids, the problem is exacerbated because a patient needs to take the steroids (especially prednisone) are the antiasthmatic agents of last resort and are widely used to treat status asthmaticus. An agent that could mimic the actions of steroids but which would work faster and/or without side effects might be the ideal antiasthmatic agent. 

Prior to the commercial development of this process benzyl alcohol was obtained from benzaldehyde [100-52-7] which undergoes the Cannizzaro reaction (2) upon treatment with potassium hydroxide. High yields of benzyl alcohol and potassium benzoate are obtained by this route which cannot compete with the present day process because of the high cost of benzaldehyde (qv). 

Present Day Methods, In the Grignard Sjnthesis (82,83), chlorobenzene [108-90-7] is converted to phenyhnagnesium chloride which reacts with ethylene oxide [75-21-8] at 100°C to give P-phenylethoxy magnesium chloride which is then decomposed with sulfuric acid to give PEA. 

Direct electrolysis was used at one time for the oxidation step. Manganese dioxide has also been used as an oxidant. Most present day processes use chlorine ... 

An earlier procedure for the production of choline and its salts from natural sources, such as the hydrolysis of lecithin (23), has no present-day apphcation. Choline is made from the reaction of trimethyl amine with ethylene oxide [75-21-8] or ethylene chlorohydrin [107-07-5J. 

Consequendy, the figures of Table 7 are stiU appHcable to the present day. More recent independent reviews (27,28) indicate a slighdy lower wodd output of 750,000 to 800,000 t/yr. With the present state of the wodd economy in 1993 the growth rate for the industry is likely to be as low as 2—3%, but even this low figure represents something like an additional 20,000 t/yr. The major dye producing countries and companies in Western Europe are shown in Table 8. 

At the same time, however, considerable research was being done, especially in Germany, on a novel process called emulsion polymerization, in which the monomer was polymerized as an emulsion in the presence of water and soap. This seemed advantageous since the product appeared as a latex, just like natural mbber, leading to low viscosity even at high soHds content, while the presence of the water assured better temperature control. The final result, based mainly on work at the LG. Farbenindustrie (IGF) (10), was the development of a butadiene—styrene copolymer prepared by emulsion polymerization, the foremnner of the present-day leading synthetic mbber, SBR. 

E. Yablonovitch and E. O. Kane,/. Ughtwave Tech. LT-4, 504 (1986). In present-day semiconductor lasers, does not extend all the way down into the valence band as shown in Eigure 1, penalizing efficiency. 

Cost Indices The value of money will change because of inflation and deflation. Hence cost data can be accurate only at the time when they are obtained and soon go out of date. Data from cost records of equipment and projects purchased in the past may be converted to present-day values by means of a cost index. The present cost of the item is found by multiplying the historical cost by the ratio of the present cost index divided oy the index applicable at the previous date. Ideally each cost item affected by inflation should be forecast separately. Labor costs, construction costs, raw-materials and energy prices, and product prices all change at different rates. Composite indices are derived by adding weighted fractions of the component indices. Most cost indices represent national averages, and local values may differ considerably. 

Introduction Many present-day commercial gas absorption processes involve systems in which chemical reactions take place in the liquid phase. These reactions generally enhance the rate of absorption and increase the capacity of the liquid solution to dissolve the solute, when compared with physical absorption systems. 

Present-day nomenclature is partly the result of the conflict and interplay of two functions the need to communicate in speech and on the printed page on the one hand, and the need for archival storage of information and its efficient, reliable retrieval. The former function came first, and laid the basis for the nomenclature most commonly used even today, and gave birth to a wealth of trivial names (i.e. names that give little or no information on structure). These were often coined on the basis of the origin of the substance, as in the case of collidine, obtained from distillation of bones in glue factories, or were derived from a special characteristic, as in the case of skatole, which has a fecal odor. Such names are short and generally euphonious, but they must be memorized they cannot be deduced from the structure. 

Therefore the problem of development of express, inexpensive and simple in use test-methods for determination of volatile amines is of present day interest. 

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