Allen studies

The elastic energy of inhomogeneous, anisotropic, ellipsoidal inclusions can be studied using Eshelby s equivalent-inclusion method. Chang and Allen studied coherent ellipsoidal inclusions in cubic crystals and determined energyminimizing shapes under a variety of conditions, including the presence of applied uniaxial stresses [11]. 

T. J. Allen, Studies of N-terminal templates for alpha-helix formation synthesis and conformational analysis of peptide conjugates of (2S,5S,8S,11S)-l-acetyl-l,4-diaza-3-keto-5-carboxy-10-thiatricyclo[2.8.1 04,8]tridecane (Ac-Hell -OH),/. Org. Chem. 1991, 56, 6683-6697. 

The reaction is very sensitive to metal ion catalysis, particularly by Cu " and Ag", and oxygen inhibits the reaction. Po and Allen studied the uncatalysed reaction in oxygen-free solutions containing 10 M EDTA to ensure that the concentrations of free metal ions were insignificant. Under these conditions the reaction is first order with respect to peroxodisulphate and the rate is essentially independent of oxalate concentration (there is a slight increase in the first-order rate coefficient with increase of oxalate concentration). Allyl acetate inhibits the reaction and reduces the rate to that observed in the absence of oxalate. In the range pH 0.5-10.3 a rate maximum occurs at pH 4.5. The first-order rate coefficient for the reaction using 0.08 M disodium oxalate is expressed by... 

Ben-Zvi and Allen studied the cupric ion-catalysed reaction. As in the uncatalysed reaction the kinetics are first order with respect to peroxodisulphate and zero order with respect to oxalate. The order with respect to total copper is half, the rate expression being... 

J.A. Allen, Studies in Innovation in the Steel and Chemical Industries. A.M. Kelley, New York, 1968. 

Smith , DeWitt JG, Hedman B, Hodgson (1994) Sulfur and chlorine -edge X-ray absorption spectroscopic studies of photographic materials. J Am Chem Soc 116 3836-3847 Sodhi RNS, Brion CE (1985a) High resolution carbon Is and valence shell electronic excitation spectra of trans-1,3-butadiene and allene studied by electron energy loss spectroscopy. J Electron Spec Rel Phen 37 1-21... 

For the case of oxyanion, two factors were found to play a role. The size and nature of the ring in which enyne-allene is embedded as well as the steric bulk of the substituents of the allene and alkyne affects the competition between the two cyclizations. The Myers-Saito product is not observed for alkynes with the trimethylsilyl substituent even for cyclohexane-annulated compounds. However, when the alkynyl substituent is changed to phenyl, the resulting relief of steric strain in the C2-C7 transition state permits the cyclization of 25 to occur at low temperature and yields the styrene derivative 26 The cyclopentane-annulated compounds give the Myers-Saito product, or fail to react when a bulky silyl substituent is present at the alkynyl terminus. In contrary, the benzene-annulated compounds undergo rapid the Schmittel cyclization dominantly or exclusively. The cyclizations of oxyanion-substituted enyne-allenes studied in the cited article occured at far lower temperatures than the analogous cyclizations of neutral enyne-allenes. The presence of the oxyanion presumably stabilizes, by resonance, the diradical in the transition state. ... 

F. M. Allen, Studies Concerning Glycosuria and Diabetes, p. 982, Wm. Leonard. 

Jones R, Tredgold R H, Hoorfar A, Allen R A and Hodge P 1985 Crystal-formation and growth in Langmuir-Blodgett multilayers of azobenzene derivatives—optical and structural studies Thin Solid Films 134 57-66... 

Tredgold R H, Allen R A and Hodge P 1987 X-ray-diffraction and optical studies of Langmuir-Blodgett films formed from azobenzene derivatives Thin Solid Films 155 343-52... 

The vibronic coupling model has been applied to a number of molecular systems, and used to evaluate the behavior of wavepackets over coupled surfaces [191]. Recent examples are the radical cation of allene [192,193], and benzene [194] (for further examples see references cited therein). It has also been used to explain the lack of structure in the S2 band of the pyrazine absoiption spectrum [109,173,174,195], and recently to study the photoisomerization of retina] [196],... 

For many years the synthesis and chemical properties of allenes has been a major area of interest in this laboratory. In our NMR research group we studied the H and lie behaviour of these compounds. 

Structural studies show allene to be nonplanar As Figure 10 7 illustrates the plane of one HCH unit is perpendicular to the plane of the other Figure 10 7 also portrays the reason for the molecular geometry of allene The 2p orbital of each of the terminal car bons overlaps with a different 2p orbital of the central carbon Because the 2p orbitals of the central carbon are perpendicular to each other the perpendicular nature of the two HCH units follows naturally... 

The remainder of this chapter focuses on practical aspects of the preparation and implementation of atomistically based computations of nucleic acids. A flow diagram of the steps involved in system preparation and the performance of MD studies of nucleic acids is presented in Figure 1. Additional details on many of the procedures described here may be found in books by Allen and Tildesly [123] and Frenkel and Smit [124]. 

Allen, P. J. et al., 1990, Summary of CANDU-6 Probabilistic Safety Assessment Study Results, Nuclear Safety 31, 2, pp 202-214. 

Fluorinated allenes are especially reactive in cycloadditions because of their highly strained double bonds [118, 119] 1,1-Difluoro- and 1-fluoroallene readily undergo both [2+2] and [4+2] cycloadditions [118 124] (equations 50-52) Exten sive studies of stereochemistry and regioselectivity show that cyclobutane forma-... 

Nonfluonnated allenes also readily react with fluoroalkenes to give diverse fluonnated alkylidenecyclobutanes [727, 12S, 129, 130] (equations 55 and 56), except for tetramelhylallene, which rearranges to 2,4-dimethyl 1,3-pentadiene under the reaction conditions prior to cycloaddition (equation 57) Systematic studies of l,l-dichloro-2,2-difluoroethylene additions to alkyl-substituted allenes establish a two-step, diradical process for alkylidenecyclobutane formation [131, 132, 133]... 

Unstable chlorides were converted to stable SnCU complexes. In their IR spectra there is an intense absorption band in the 1900 cm region, which is consistent with the band of allenic system (structure C). Unlike unstable chlorides A and B, the SnCl4 complexes are stable and, when kept in an inert atmosphere, remain intact for several days. The allenic structure of the immonium salt was confirmed by studying the mercuration of the same aminobutenynes (74DIS). 

Following studies on the rearrangement of allylic arenesulfinates, Braverman and coworkers have investigated a number of natural extensions of this unique transformation, including the predictable [2,3] sigma tropic rearrangements of allylic sulfenates to sulfoxides and of propargylic sulfenates and sulfinates to allenic sulfoxides and sulfones respectively. The last reaction is described below, while the other two are described in Chapter 14. 

Analogous with the rearrangement of allylic sulfoxides is the [2,3]-sigmatropic rearrangement of propargylic sulfoxides to allenic sulfenates. This process, which has been relatively little studied so far, appears to be the first step in the facile and quantitative rearrangement of sulfoxide 98 to the hemithioacetal 101 (equation 45)167. This reaction,... 

Values found for interatomic distances and bond angles in the thirteen hydrocarbons studied are given in Table XIV. The carbon-carbon singlebond distance is found to have the constant value 1.54 = = 0.02 A., being unaffected by the presence of an adjacent double bond or benzene nucleus (provided that it does not form part of a conjugated system). The carbon-carbon double-bond distance in allene and acetylene has the value 1.34 A. This is 0.04 A. less than that formerly given by the table of covalent radii, which has accordingly been revised. The effect of the revision on the bond distance-resonance curve is discussed. 

According to a study conducted by Allen et al. (2000), mentors (both male and female) are biased towards selecting mentees based on their perceptions of the mentee s potential/ability rather than perceptions of his or her need for help. This means that the extent of a mentee s need for help is not as important a determinant in mentee selection as is his or her perceived potential to grow and develop. 

Other conjugated systems, including trienes, enynes, diynes, and so on, have been studied much less but behave similarly. 1,4 Addition to enynes is an important way of making allenes ... 

Even substituted allenes, RCH=C=CH2, are protonated at the 1 position, giving methyl ketones by hydration (60-63) and mostly 2-halo-2-alkenes, RCH=CXCH3, by the addition of hydrogen halides (62, 64, 65). Jacobs and Johnson (65), in a careful study, have shown that addition of HCl to... 

The addition of isocyanates (isoelectronic to CO) to group 14 carbene analogs was investigated in order to see if the resulting molecules w ould have an allene-like framework. In the first study, Wcidenbruch et attempted to synthesize... 

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