This Century

The Reactor Safety Study (RSS) directed by Professor Norman Rasmussen of MIT may have had its beginnings in a letter from Senator Pastore to James Schlesinger, AEC Chairman, requesting risk information for the Price-Anderson renewal. The RSS study began in September 1972 with Saul Levine, full-time staff director assisted by John Bewick and Thomas Murley (all AEC). 

A significant development of the study was the use of event trees to link the system fault trees to (lie accident initiators and the core damage states as described in Chapter 3. This was a response to the ditficulties encountered in performing the in-plant analysis by fault trees alone. Nathan Villalva and Winston Little proposed the application of decision trees, which was recognized by Saul Levine a.s providing the structure needed to link accident sequences to equipment failure. 

The Reactor Safety Study was the most important development in PSA because it  

The work was published as draft WASH-1400 in August 1974 and extensively reviewed. The revised report was published as WASH-1400 (FINAL) in October 1975. 

Following the release of WASH-1400, the techniques were disseminated by the authors and interpreters through publications, lectures, and workshops. Many organizations set up in-housc PS. groups, and the nucleus of the organization that had produced the Reactor Safety Study coiKinucd at the NRC. 

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Undeniably, one of the most important teclmological achievements in the last half of this century is the microelectronics industry, the computer being one of its outstanding products. Essential to current and fiiture advances is the quality of the semiconductor materials used to construct vital electronic components. For example, ultra-clean silicon wafers are needed. Raman spectroscopy contributes to this task as a monitor, in real time, of the composition of the standard SC-1 cleaning solution (a mixture of water, H2O2 and NH OH) [175] that is essential to preparing the ultra-clean wafers. 

Spectroscopy, or the study of the interaction of light with matter, has become one of the major tools of the natural and physical sciences during this century. As the wavelength of the radiation is varied across the electromagnetic spectrum, characteristic properties of atoms, molecules, liquids and solids are probed. In the... 

For a general history of titrimetry, see the following sources. Kolthoff, I. M. Analytical Chemistry in the USA in the First Quarter of This Century, Anal. Chem. 1994, 66, 24IA-249A. Laitinen, H. A. Ewing, G. W., eds. A History of Analytical Chemistry. The Division of Analytical Chemistry of the American Chemical Society Washington, DC, 1977, pp. 52-93. 

During the early years of this century, organic chemists were enjoying success in determining the structures of ordinary-sized organic molecules, and this probably contributed to their reluctance to look beyond structures of convenient size. Physical chemists were interested in intermolecular forces at this period, and the idea that polymers were the result of some sort of association between low molecular weight constituent molecules prevailed fora long while. 

With the inception of smart materials and stmctures, the world is on the brink of a new material age. Within this century the polymer age and the composite age have been experienced. These have now been foUowed by the smart material age. The implementation of smart materials into smart stmctures describes the smart material age more accurately. 

Such repositioning inevitably means reduced production volume, and for the first time this century production in the last decade has been below that a decade earUer (Eig. 9). Most capacity reductions have been in North America and especiaUy eastern Europe. This has been offset in part by capacity increases in the Ear East. Rayon is no longer a significant component of carpets, and has lost the disposable diaper coverstock business to cheaper and more easUy processed polypropylene. It has, however, gained share in health and hygiene products and is now a principal component of tampons worldwide. 

Chemical analyses of stream water that have been pubhshed since the early years of this century generally include deterrninations for four positively charged ions (cations)—calcium (Ca ), magnesium (Mg ), sodium (Na ), and potassium (K )—and five negatively charged ions... 

The success of quinine inspired the search for other antimalarials. The greatest impetus for the development of synthetic dmgs came this century when the two World Wars intermpted the supply of cinchona bark to the combatants. A stmcturally related 4-quinolinemethanol is mefloquine (65, Lariam [51773-92-3]) which now serves as an effective alternative agent for chloroquine-resistant P. falciparum. This is a potent substance that requires less than one-tenth the dose of quinine to effect cures. There are some untoward side effects associated with this dmg such as gastrointestinal upset and dizziness, but they tend to be transient. Mefloquine is not recommended for use by those using beta-blockers, those whose job requires fine coordination and spatial discrimination, or those with a history of epilepsy or psychiatric disorders. A combination of mefloquine with Fansidar (a mixture of pyrimethamine and sulfadoxine) is known as Fansimef but its use is not recommended. Resistance to mefloquine has been reported even though the compound has not been in wide use. 

From the beginning of this century, the demand for asbestos fibers grew in a spectacular fashion for numerous applications, in particular for thermal insulation in steam engines and technologies (4). Moreover, the development of the Hatschek machine in 1900 for the continuous fabrication of sheets from an asbestos—cement composite opened an important field of industrial application for asbestos fibers. 

Activated alumina and phosphoric acid on a suitable support have become the choices for an iadustrial process. Ziac oxide with alumina has also been claimed to be a good catalyst. The actual mechanism of dehydration is not known. In iadustrial production, the ethylene yield is 94 to 99% of the theoretical value depending on the processiag scheme. Traces of aldehyde, acids, higher hydrocarbons, and carbon oxides, as well as water, have to be removed. Fixed-bed processes developed at the beginning of this century have been commercialized in many countries, and small-scale industries are still in operation in Brazil and India. New fluid-bed processes have been developed to reduce the plant investment and operating costs (102,103). Commercially available processes include the Lummus processes (fixed and fluidized-bed processes), Halcon/Scientific Design process, NIKK/JGC process, and the Petrobras process. In all these processes, typical ethylene yield is between 94 and 99%. 

For many industrialized countries, efforts to improve the outdoor air quality have been under way for the majority of this century. In many locations around the world, significant improvements have taken place. Air quality in many major cities such as London, New York, and Chicago has improved from the conditions present in the first half of the twentieth century. Mechanisms and control programs are in place in the developed countries to continue the improvement of ambient air quality. Considerable effort and energy have been expended to characterize, evaluate, and control air pollution emissions to the atmosphere. 

Both of these crucial fields of research will surface repeatedly later in this book here they are briefly discussed only as fields which by at least one of the criteria I have examined do not appear to qualify as fully blown disciplines. Both have emerged only in this century, because a knowledge of crystal structure is indispensable to both and that only emerged after 1912, when X-ray diflfraction from crystals was discovered. 

Around the beginning of this century, cancer and illness was associated with excessive use of X-rays. Watch dial painters got mouth cancer from radium in the paint. It soon was realized that radiation has health effects. The measures of energy deposition concepts introduced... 

Destructive analytical procedures, which were mostly developed at the beginning of this century for inorganic compounds, have been modified, revised, and established for the determination of fluorine in organofluorine compounds. 

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