The Sixties

Sealed metal-ceramic X-ray tubes are in use since the sixties. Whereas glass tubes still are the most common known form of X-ray tubes in the public, and are certainly the most used technology firom point of view of sold tubes per year, metal-ceramic X-ray tubes in lots of applications are state-of-the-art. 

We admire human creation second - The Beatles and Bob Dylan, heroes from the sixties whose music and lyrics changed a whole generation. In the twenties Pablo Picasso and Paul Klee were among the artists who changed our conception of art. 

Cycloaddition reactions are close to the heart of many chemists - these reactions have fascinated the chemical community for generations. In a series of communications in the sixties. Woodward and Hoffmann [2] laid down the fundamental basis for the theoretical treatment of all concerted reactions. The basic principle enunciated was that reactions occur readily when there is congruence between the orbital symmetry characteristics of reactants and products, and only with difficulty when that congruence is absent - or to put it more succinctly, orbital symmetry is conserved in concerted reactions [3]. 

The basis of the Diels-Alder reaction developed in the twenties, and the contribution by Woodward and Hoffmann in the sixties, are two very important milestones in chemistry. Both discoveries were met with widespread interest the applications made are fundamental to modern society the tests which it has survived and the corollary predictions which have been verified are impressive. 

Remember that, on Maher s view, the successful prediction of two new elements counted for more than the prior successful accommodation of the then known sixty-two elements—because the two successes dispelled the scepticism that had existed despite the sixty-two successful accommodations.) Since we shall again need to... 

York. There s a seventeen-dollar cocktail. On Monday night, I went up to the Rainbow Grill, on the sixty-fifth floor of Rockefeller Center—what s left of the Promenade Bar, which originally accompanied the Rainbow Room, once the city s most famous supper club. I was looking for a French 75. 

This is the sixty-first volume in the series THE CHEMISTRY OE HETEROCYCEIC COMPOUNDS... 

Heavy metals. The profiles of sediment and pollutant depositions and the relationships of concentrations with time have been reconstructed. For most metals the highest accumulations took place between the fifties and the sixties, when the fastest industrial development of Porto Marghera took place. In Figure 2 the concentration profiles of three of the most interesting metals (Hg, Pb, Cd) are plotted vs. depth. Data were "normalized" (i.e. divided) by the background levels, as metals have different natural presence in the environment. This leads to accumulation factors, referred to pre-industrial background values. Any derived data tell... 

Addition of phosphonyl radicals onto alkenes or alkynes has been known since the sixties [14]. Nevertheless, because of the interest in organic synthesis and in the initiation of free radical polymerizations [15], the modes of generation of phosphonyl radicals [16] and their addition rate constants onto alkenes [9,12,17] has continued to be intensively studied over the last decade. Narasaka et al. [18] and Romakhin et al. [19] showed that phosphonyl radicals, generated either in the presence of manganese salts or anodically, add to alkenes with good yields. 

Phosphoranyl radicals were observed by FPR at the end of the sixties [91]. For a long time, phosphoranyl radicals, particularly the alicyclic ones [59], were considered as elusive species. However, recently. Marque et al. [92] observed the first strongly persistent (ti/2=45 min at RT) alicyclic phosphoranyl radicals (Fig. 10) when they irradiated bis(trialkylsilyl)peroxides in the presence of tris(trialkylsilyl)phosphites. The increased lifetime of the ensuing phosphoranyl radicals is a consequence of the presence of four bulky R3SiO groups around the phosphorus. The bulkiness of the substituents hampers the dimerization and the Sh2 reaction of phosphoranyl radicals with the peroxide initiator. Furthermore, the high strength of the P-0 and 0-Si bonds results in slow a- and p-scissions [93]. 

In the sixties of past century, a few patents issued to Bergbau Chemie [5,48,49] and to Mobil Oil [50-52], respectively described the use of CFPs as supports for catalytically active metal nanoclusters and as carriers for heterogenized metal complexes of catalytic relevance. For the latter catalysts the term hybrid phase catalysts later came into use [53,54], At that time coordination chemistry and organo-transition metal chemistry were in full development. Homogeneous transition metal catalysis was expected to grow in industrial relevance [54], but catalyst separation was generally a major problem for continuous processing. That is why the concept of hybrid catalysis became very popular in a short time [55]. 

We need to understand better why being a member of the drug culture became so highly valued. Until the sixties, drug abuse... 

But nuclear energy has problems in the U.S.. Since the 1973 Arab oil boycott there has been a surplus of electrical capacity in the US. and no large base load electrical plants have been ordered. Indeed, some 100 nuclear plants and some 80 coal plants on order were canceled after 1973. The sixty nuclear plants put on the line since 1973 (providing 40% of new electricity capacity) were all ordered before 1973. And because there was no urgent need, bureaucratic licensing procedures and litigious court attacks by anti-nuclear groups have led to construction times of a dozen to twenty years, and uneconomic costs. This compares to the four to six year construction times ofthe U.S. reactors built abroad and indeed to the four to six year construction times in the U.S. priorto 1973. 

In the sixties, such reactions were of greater interest as a source of 1,3-disilacyclobutanes (eq. 4) [9]. 

Introductory Remarks. In contrast with the popularity and usefulness of the polysiloxane chains, which constitute the structural backbone of silicones, the knowledge of polymers based on the silazane unit is still limited. In the sixties there was still some hope of the possibility of producing long chain polysilazane molecules and a number of laboratories were active in seeking convenient methods for their synthesis (e.g. see review by Aylett (12)). 

These principles of macromolecular organization replaced the naive vision of some of the early molecular biologists, who tried to reduce each complex structure and function of organisms directly to one (or a limited number of) proteins or other macromolecules. The best example of this simplistic reductionist approach was the efforts aiming in the sixties at discovering the molecules of memory - molecules that allegedly encoded the memories or behaviors. Many articles and books1 were devoted to this search, without any success. 

In the sixties and seventies, theoretical chemistry had developed a somewhat uncertain reputation. At that time, the computational means did not really allow the performance of... 

Despite its obvious importance, the interpretation and even the measured yields in the radiolysis of water vapor were doubtful until the sixties. It was not because of lack of experimental data rather, it was because of difficulties of comparing measurements of different workers due to artifacts and sheer experimental problems (Anderson, 1968). The greatest discrepancy is in the reported hydrogen yields, which varied between the extremes by a factor of -104 (Dixon, 1970 Anderson, 1968). It is now agreed that G(H2) in water vapor at 1021 eV/g varies around 10-3. But, as pointed out by Dixon, the absolute yield of hydrogen in pure water vapor is not a very meaningful quantity, because a steady state is achieved and a consistent steady state concentration of H2 and 02 may be... 

As for the relative suitability of an electron beam (EB) facility vis-a-vis a cobalt-60 gamma facility, a key point is that although the ultimate chemistry is nearly identical in both cases, there is a notable difference in the penetration of the radiations. Another point is that the large capacity and consequent cost of EB machines require a relatively large production rate to justify their use. On the other hand, the EB machine, not being a radioactive source, is completely safe when switched off. Overall, since the sixties, sterilization by irradiation has steadily increased. However, most of this is by cobalt-60 gamma irradiation, the EB machines accounting for about a fifth or sixth of the total number of facilities. 

FAO/WHO (2006) Summary and conclusions of the sixty-seventh meeting of the Joint FAO/ WHO Expert Committee on Food Additives (JECFA), 20-29 June 2006. JECFA, Rome... 

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