Z 1 3 5 Hexatriene

E. G. MacRae and H. D. Hagstrom, Treatise on Solid State Chemistry, Vol. 6A, Part I, Plenum, New York, 1976.  [c.323]

Klapper, I., Hagstrom, R., Fine, R., Sharp, K., Honig, B. Focusing of electric fields in the active site of cu,zn superoxide dismutase. Proteins Struct. Pune. Genet. 1 (1986) 47-79.  [c.195]

In his book [16], Hagedorn classifies all energy level crossings that can occur generically with an electronic Hamiltonian according to the associated symmetries. Each symmetry yields a finite number of typical, generic energy level  [c.388]

For Hagedorn s initial condition Eq. (21), we have to choose ft — 2/ in Eq. (15).  [c.392]

Hagedorn, G. A. A time dependent Born-Oppenheimer approximation. Comm. Math. Phys. 77 (1980) 1-19  [c.394]

Hagedorn, G. A. Electron energy level crossing in the time-dependent Born-Oppenheimer approximation. Theor. Chim. Acta 67 (1990) 163-190  [c.394]

There are, however, two areas in which graphic methods have had a significant effect on both process design and process control. The synthesis of heat-exchange networks is an exercise in examination of multiple combinations of hot and cold streams transferring heat across heat-exchanger nodes. The network synthesis methods (103) are intrinsically graphic in approach. An interactive software package, RESHEX (104,105) has been developed to implement this approach. The HEXTRAN program by Simulation Sciences, Inc., is another example of the automation of heat-exchanger network design.  [c.64]

I Klapper, R Hagstrom, R Erne, K Sharp, B Honig. Proteins 1 47, 1986.  [c.149]

Professor Colin Russell, historian of science and emeritus professor at the Open University, gave me helpful counsel on the history of chemistry and showed me how to take a philosophical attitude to the disagreements that beset the relation between practising scientists and historians of science. I am grateful to him.  [c.583]

Thus, the time-dependent BO model describes the adiabatic limit of QCMD. If QCMD is a valid approximation of full QD for sufficiently small e, the BO model has to be the adiabatic limit of QD itself. Exactly this question has been addressed in different mathematical approaches, [8], [13], and [18]. We will follow Hagedorn [13] whose results are based on the product state assumption Eq. (2) for the initial state with a special choice concerning the dependence of 4> on e  [c.387]

Pig. 5. Comparison of the qi expectation value of the uncoupled QCMD bundle ([g]e o) and full QD ( q)qd) for the test system for e = 1/100 (pictures on top) and e = 1/500 (below). Initial data as in Fig. 3. The shaded domain indicates the funnel between the two curves Qbo and geo (cf. Thm. 5). The light dashed line shows Hagedorn s limit solution qna and the dense lines (q )Qo (left hand pictures) and [ ]e s (right hand pictures).  [c.394]

Hagedorn, G. A. Proof of the Landau-Zener formula in an adiabatic limit with small eigenvalue gaps. Commun. Math. Phys. 136 (1991) 433-449 Hagedorn, G. A. Molecular propagation through electron energy level crossings. Mem. Amer. Math. Soc. 536 (1994) 130pp  [c.395]

Klapper 1, R Hagstrom, RFine, K Sharp and B Honig 1986. Focusing of Electric Fields in tire Actir e Sit of CuZn Superoxide Dismutase Effects of Ionic Strength and Amino-Acid Substitution. Proteins Structure, Function and Genetics 1 47-59.  [c.651]

The application of scientific techniques to the study of art objects is an interdisciplinary undertaking (1 7). The physical scientist is trained to approach a stated problem by analysing for the identification of measurable variables and devising means to obtain numerical values for these variables. On the other hand, the art historian rehes on the trained eye, enabling visual recognition of styUstic characteristics and the mote subjective comparison of these with observations about numerous other art works. Communication between these speciaUsts has requited mutual efforts. The development of scientific examinations of art objects has had a synergistic relation with the growth of a new profession that of the art conservator, a speciahst having both scientific and artistic training. The conservator consults and coUaborates with both scientists and curators, providing appropriate cate to objects in the collections to promote long-term preservation.  [c.416]

W. W. HiUstrom, Formation of Pyrophoric Fragments, BRL MR 2306, AD 765447, Ballistics Research Laboratory, Aberdeen, Md., 1973.  [c.353]

Module design is veiy important for this case, as the high Ot may result in high permeate partial pressure. An example is the separation of HgOTrom air.  [c.2048]

With the number of known organic compounds approaching five million, more than half of which are heterocyclic, the requirements of nomenclature put a substantial strain on language. The chemists who first consciously dealt with heterocyclic compounds could have had no idea of the magnitude of the subject, and their efforts, which were adequate when the world of chemistry was young and uncluttered, have had to be amended, augmented and transformed at intervals, much as the small cottage of a young couple may be expanded to accommodate new children, meet new building code requirements and provide increased comfort and convenience. The result in both cases is somewhat of a patchwork. The purpose of this chapter is primarily to provide a guide to accepted practice today, but it is also necessary to consider practices of the past, for it is the nature of organic chemistry that chemists may often have need to read the literature of half a century or more ago. A knowledge of older customs of nomenclature is thus of distinct practical value, and is not just the concern of the historian.  [c.8]

It is also clear that it is difficult to relate cause and effect to any specific chemical since, with the exception of point source effluents, many waterways contain a multitude of chemicals, of which the active endocrine disruptor may not be that which has been measured in the water or tissue. For such reasons, many studies have used in vitro experiments in which isolated tissue, either from a control animal or one captured in a polluted water system, is exposed to a single pollutant in the laboratory. Such experiments have shown significant disruption to testicular activity by a wide range of xenobiotics, including cadmium, lindane, DDT, cythion, hexadrin and PCBs.  [c.36]

John Ziman is a renowned theoretical solid-state physicist who has turned himself into a distinguished metascientist (one who examines the nature and institutions of scientific research in general). In fact, he has successfully switched disciplines. In a lecture delivered in 1995 to the Royal Society of London (Ziman 1996), he has this to say Academic science could not function without some sort of internal social structure. This structure is provided by subject specialisation. Academic science is divided into disciplines, each of which is a recognised domain of organised teaching and research. It is practically impossible to be an academic scientist without locating oneself initially in an established discipline. The fact that disciplines are usually very loosely organised (my italics) does not make them ineffective. An academic discipline is much more than a conglomerate of university departments, learned societies and scientific journals. It is an invisible college, whose members share a particular research tradition (my italics). This is where academic scientists acquire the various theoretical paradigms, codes of practice and technical methods that are considered good science in their particular disciplines... A recognised discipline or sub-discipline provides an academic scientist with a home base, a tribal identity, a social stage on which to perform as a researcher. Another attempt to define the concept of a scientific discipline, by the science historian Servos (1990, Preface), is fairly similar, but focuses more on intellectual concerns By a discipline, I mean a family-like grouping of individuals sharing intellectual ancestry and united at any given time by an interest in common or overlapping problems, techniques and institutions . These two wordings are probably as close as we can get to the definition of a scientific discipline in general.  [c.21]

The concept of an invisible college , mentioned by Ziman, is the creation of Derek de Sofia Price, an influential historian of science and herald of scientomet-rics (Yagi et al. 1996), who wrote at length about such colleges and their role in the scientific enterprise (Price 1963, 1986). Price was one of the first to apply quantitative  [c.21]

In the United States, physical chemistry grew directly through the influence of Ostwald s 44 American students, such as Willis Whitney who founded America s first industrial research laboratory for General Electric (Wise 1985) and, in the same laboratory, the Nobel prizewinner Irving Langmuir (who began his education as a metallurgist and went on to undertake research in the physical chemistry of gases and surfaces which was to have a profound effect on industrial innovation, especially of incandescent lamps). The influence of these two and others at GE was also outlined by the industrial historian Wise (1983) in an essay entitled Ionists in Industry Physical Chemistry at General Electric, 1900-1915 . In passing. Wise here remarks Ionists could accept the atomic hypothesis, and some did but they did not have to . According to Wise, to these pioneers, an ion was not a mere incomplete atom, as it later became for scientists . The path to understanding is usually long and tortuous. The stages of American acceptance of the new discipline is also a main theme of Servos s (1990) historical study.  [c.28]

Reverting to the path from Biringuccio and Agricola towards modern scientific metallurgy, Cyril Smith, whom we have already met and who was the modern master of metallurgical history (though, by his own confession (Smith 1981), totally untrained in history), has analysed in great detail the gradual realisation that steel, known for centuries and used for weapons and armour, was in essence an alloy of iron and carbon. As he explained (Smith 1981), up to the late 18th century there was a popular phlogiston-based theory of the constitution of steel the idea was that iron was but a stage in the reduetion to the purest state, which was steel, and it was only a series of painstaking chemical analyses by eminent French scientists which finally revealed that the normal form of steel was a less pure form of iron, containing carbon and manganese in particular (by the time the existence of these elements was recognised around the time of the French revolution). The metallurgical historian Wertime (1961), who has mapped out in great detail the development of steel  [c.94]

At one point it seemed that the entire theoretical superstructure advanced to explain Hume-Rothery s electron phases had collapsed, because of Pippard s (1957) discovery that the Fermi surface of pure copper was not after all spherical and already touched the first Brillouin zone even before any polyvaleni solute was added (Figure 3.27, right). This seemed to remove the essential concept from Jones s theory, and thus the agreement between Hume-Rothery s experimental findings and Jones s theory appeared to be merely fortuitous. But, as the science-historian Gerald Holton once remarked, The graveyard of failed scientists is littered with those who did not suspend disbelief when their ideas were first shown to be wrong . In due course, the apparent disaster was seen not to be one after all. Cottrell, in a little textbook on electron theory published just half a century after his first book (Cottrell 1998) explains what happened Because of the absence of computers in the 1930s. Jones had to make a number of simplifying approximations in developing his theory, one being the so-called rigid-band approximation - that the form of the density-of-states distribution remains fixed as the electron-to-atom ratio increases, another being that the Fermi surface remains spherical even when it touches a Brillouin zone boundary. Even though Jones modified some of his approximations in 1937, Pippard s study still seemed to undermine the theory, but in fact it became clear later that some of the theoretical errors revealed by this study cancelled each other. (This is a not uncommon experience in the history of theoretical science.) The new theory (Paxton et at. 1997) avoids Jones s approximations, takes proper account of the influence of d electrons (which Jones could not do), and, in Cottrell s words "The modern theory, by taking full advantage of present-day computer power, has been able to avoid both approximations and so, because of their mutual cancellation, has achieved the same success - or even better - but on an intrinsically more sound basis ,  [c.137]

Stephen Keith, a historian of science, has examined the development of this parepisteme (Keith 1998), complete with the stops and starts caused by fierce competition between individuals and the discouragement of some of them, while a shorter account of the evolution of crystal-growing skill can be found in the first  [c.160]

The early path of scientists in Russia was not an easy one, especially for those precocious individuals who were far ahead of their contemporaries. In Chapter 3, I mentioned Federov, one of the three co-inventors of the theory of space groups in the late nineteenth century, who found no comprehension at home of his difficult ideas. Here I can also refer to Mikhail Vasilevich Lomonosov (1711-1765), an early Russian polymath, a scientist and litterateur, who took an interest in the whole of science as it was perceived in the Petersburg of his day. He insisted on the crucial bond between chemistry and physics long before Wilhelm Ostwald was born ( a chemist lacking knowledge of physics is like a blind man who seeks by touch ) he took an active part in improving glass technology in his native country he put paid to the phlogiston theory well before Lavoisier did. These facts come from an as-yet unpublished essay on Lomonosov by a British science historian, Michael Hoare,  [c.531]

Next, I want to acknowledge my deep debt to the late Professor Cyril Stanley Smith, metallurgist and historian, who taught me much of what 1 know about the proper approach to the history of a technological discipline and gave me copies of many of his incomparable books, which are repeatedly cited in mine.  [c.583]

Naval Research Laboratory, Code 6176, Washington, DC 20375-5342, USA Hysitron Inc., Minneapolis, MN 55439, USA  [c.193]

See pages that mention the term Z 1 3 5 Hexatriene : [c.182]    [c.388]    [c.393]    [c.621]    [c.186]    [c.477]    [c.247]    [c.417]    [c.111]    [c.470]    [c.307]    [c.307]    [c.447]    [c.460]    [c.461]    [c.257]    [c.219]    [c.429]    [c.60]    [c.68]    [c.166]    [c.177]    [c.152]   
Carey organic chemistry (0) -- [ c.0 ]