Diode laser measurements of the band strengths of ν3 and ν6 in 12CH3D

A diode laser spectrometer has been used to measure line strengths for 143 transitions in the ν₆ fundamental band of ¹²CH₃D near 9 μm. These line-strength measurements have been used to derive a band strength for ν₆ and ν₃. The band strength derived for ν₆ is 61.7 ± 1.8 cm^?2 atm^?1, and that for ν₃ is 49.3 ± 1.4 cm^?2 atm^?1 at 395 K.     

Constraints on the degree of a sofic homomorphism and the induced multiplication of measures on unstable sets

Letf be an endomorphism of an irreducible sofic systemS, whereS has entropy log λ. Thedegree off is the numberd such thatf isd to 1 almost everywhere. Thend divides a power of the greatest common divisor of the nonleading coefficients of the minimal polynomial of λ. Also,f multiplies the natural measure on unstable sets of generic points by a positive unit of the ring generated by 1/λ and the algebraic integers ofQ[λ]. Related results hold for bounded to one homomorphisms of sofic systems.     

FURTHER CHARACTERIZATION OF MONOCLONAL ANTIBODY INDICATES SPECIFICITY FOR (6–4)-DIPYRIMIDINE PHOTOPRODUCTS

Monoclonal antibody aUVssDNA-1 is produced by hybridoma cell line 25JF.C3B6 originally selected from cell fusions using spleen cells from mice immunized with UV-irradiated polydeoxynucleotides (Strickland and Boyle, Photochem. Photobiol. 34, 595-601, 1981). Original and subsequent studies of the binding characteristics of aUVssDNA-1 indicated that it was specific for cyclobuta-dithymidine photoproducts. Those investigations examined action spectrum, short-wavelength photo-reversal, nucleotide sequence effects, and photoreactivation using E. coli photolyase and incandescent light. However, the more recent studies reported here examined acetophenone-UV-B photosensitization, UV-B photoisomerization, and photoreactivation using cloned E. coli photolyase and filtered incandescent light. The results indicate that aUVssDNA-1 recognizes photoproducts with characteristics of (6-4)-dipyrimidines. Thus, previous studies in which relatively rapid repair of cyclobuta-dithymidine photoproducts was inferred using this antibody, require re-interpretation in light of these new findings.     

The phase diagram and electrical characteristics of silver iodo-phosphate fast-ion electrolytes

The equilibrium phase diagram for the $\text{AgI}\text{Ag}{}_4\text{P}{}_2\text{O}{}_7$ system of fast-ion electrolyes is established along with the conductivity-composition relationship for polycrystalline samples. The highest conductivity compound (0.07 Ω^?1 cm^?1 at 300 K) has the composition Ag₁₆I₁₂P₂O₇. Measurements of relative permittivity and conductivity over a frequency range of 50 Hz to 100 kHz and a temperature range of 77 to 320 K on polycrystalline samples and single crystals of Ag₁₆I₁₂P₂O₇ show that the conductivity and its temperature dependence is anisotropic, with a higher conductivity along the c axis and a change in the activation energy for conduction from 0.4 eV at low temperatures to 0.14 eV above 300 K. Perpendicular to the c axis the activation energy is constant with temperature (0.28 eV). This anisotropy and a frequency dispersion in the ac conductivity between 110 to 150 K is shown to originate in the crystal structure of the material and in the distribution of Ag⁺ ions between different sites.     

Asymmetric hydrogenation of methyl α-benzamido cinnamate in ionic liquid solvent

The room temperature ionic liquid EMIMOTf was employed as the sole reaction solvent for the asymmetric hydrogenation of methyl α-benzamido cinnamate. Under conditions of 60 psi hydrogen and 50 °C for 24 h, near quantitative conversions were observed using both the achiral DiPFc-Rh catalyst, and the chiral EtDuPHOS-Rh catalysts. Enantiomeric excess of 89% ee was observed for hydrogenations carried out with the chiral catalyst.     

Evaluation of four ABS resins by thermal analysis

Four new commercial grades of rubber toughened ABS (acrylonitrile-butadienestyrene) terpolymers were characterized by differential scanning calorimetry (DSC), mechanical analysis and gel permeation chromatography (GPC). These rubber toughened ABS molding compounds were manufactured by a new blended technology to yield resins which offer a broad range of flow properties and levels of toughness. Based upon DSC estimates of the level of rubber included, the four ABS compounds can be divided into two groups; the first has about 11 wt.% butadiene and the second near 18 wt.%. In addition, two styrene-acrylonitrile copolymers with different average molecular weights were found blended within each ABS group. By this blending process four resins are produced with impact strengths ranging from below three to near seven ft-lb in^–1. These analytical results show that a resin's impact strength is enhanced not only by increasing the level of rubber particles in a given ABS compound but also by raising the molecular weight of the SAN which is blended into the terpolymer.Dedicated to Professor Bernhard Wunderlich on the occasion of his 65th birthdayThe authors acknowledge useful discussions with L. L. Blyler, Jr., X. Quan and L. Shepherd and A. Hale for his scanning electron microscopy results. GPC results were carried out by Jordi Associates.     

Mechanisms of exchange modulation in trimethylenemethane-type biradicals: the roles of conformation and spin density

The molecular structures and magnetic properties of six dinitroxide biradicals are described. Five of the dinitroxides are trimethylenemethane-type (TMM-type) biradicals; that is, the intramolecular exchange parameter, J, is modulated by a carbon-carbon double bond. However, the efficacy of the carbon-carbon double bond as an exchange coupler is determined by the molecular conformation. Our results show that the exchange parameters correlate with phenyl-ring torsion angles (phi) via a simple Karplus-Conroy-type relation: J = 44 cos(2) phi - 17. Comparison of these results to those obtained for our isostructural series of bis(semiquinone) biradicals shows that both the magnitude of J and the resistance of ferromagnetic J to bond torsions is proportional to the spin density adjacent to the exchange coupler.