A SPIN LABELED RETINAL PIGMENT ANALOGUE OF THE PURPLE MEMBRANE

Abstract— A spin labeled derivative of retinal (4-[2, 2, 5,5-tetramethyl-l-pyrrolidinyloxy-3-carboxyl]-retinal) has been synthesized. The all- trans -isomer combined with the apoprotein of the purple membrane Halobacterium halobium to form a pigment which absorbs at 480 nm and which is unstable to hydroxyl-amine. The electron paramagnetic resonance (EPR) spectrum of the pigment showed an anisotropic signal indicating immobilization of the nitroxide on the chromophore. The ester linkage on the chromo-phore hydrolyzed in situ yielding the 4-hydroxypigment analogue, absorbing at 540 nm, and the free 2, 2, 5,5-tetramethyl-l-pyrrolidinyloxy-3-carboxylic acid.     

Neutrino and antineutrino charged-current inclusive scattering in iron in the energy range 20<E v <300 GeV

Inclusive charged-current interactions of high-energy neutrinos and antineutrinos have been studied with high statistics in a counter experiment at the CERN Super Proton Synchrotron. The energy dependence of the total cross-sections, the longitudinal structure function, and the nucleon structure functionsF ₂,xF ₃, and \(\bar q^{\bar v} \) are determined from these data. The analysis of theQ ²-dependence of the structure functions is used to test quantum chromodynamics, to determine the scale parameter Λ and the gluon distribution in the nucleon.     

Far-infrared reflectivity of sintered YBa2Cu3O7 in the normal and superconducting state

We report on a study of the far-infrared reflection for a sintered YBa₂Cu₃O₇ sample that contained a large portion of preferentially oriented crystallites with thea–b plane parallel to the surface and that showed extraordinary high far-infrared reflectivity. From experimental reflection data we determined, by Kramers-Kronig analysis, the dynamical conductivity and extracted the contributions due to free charge carriers and phonons, respectively. We find evidence for an anomalous behavior of the dynamical conductivity at temperatures aboveT _c ; the dynamical conductivity increases strongly for temperatures approachingT _c and is strongly frequency dependent. By use of the Mattis-Bardeen theory we obtain an estimate for the superconducting energy gap of 2/kT _c 4.6 (forTT _c ). We find that the lowest frequency infrared-active phonon mode is less damped in the superconducting state than in the normal state.     

Komplexe cyclischer Diazabutadiensysteme mit nullwertigen Metallen

Reactions of a 2,3- and a 1,4-diazabutadien ( 1 , 11 ), both incorporated in rings and thus being (s)-cis-, with molybdenum, iron and nickel carbonyls or their derivatives show the preferred coordination with lone electron pairs. The azine 1 shows a bridging tendency towards iron and molybdenum, while for the α-diimine 11 probably π-electrons participate in dative bonding.     

Electroweak parameters from a high statistics neutrino nucleon scattering experiment

The final results from the WA 1/2 neutrino experiment in the 1984 CERN 160 GeV narrow band beam are presented. The ratiosR _ν and \(R_{\bar v} \) of neutral to charged current interaction rates of neutrinos and antineutrinos in iron are measured to beR _ν=0.3072±0.0033 and \(R_{\bar v} \) =0.382±0.016. A value of the electroweak parameter sin² θ _w = 1 ?m _W ² /m _Z ² is extracted fromR _ν. The result is sin² θ _w =0.228+0.013(m _c ?1.5)±0.0003 (theor.) wherem _c is the mass of the charmed quark in GeV form _t =60 GeV,M _H =100 GeV, ρ=1. CombiningR _ν and \(R_{\bar v} \) one obtains a value for ρ=0.991+0.023(m _c ?1.5)±0.020(exp.). Alternatively,R _ν and \(R_{\bar v} \) yield a precise value of the ratio of intermediate vector boson massesm _W /m _Z =0.880?0.007(m _c ?1.5)±0.002(exp.)±0.002(theor.). Comparison of these results with those from direct measurements of the vector boson masses are presented. In a model-independent analysis the left- and right-handed neutral current coupling constants,g _L ² andg _R ² , are determined.     

Prompt neutrino results from a proton beam dump experiment

A study of prompt neutrino events from 400 GeV protons on a beam-dump is presented. The ratio of electron- to muon-neutrino rates is 0.86±0.14, in agreement withe– universality. The anti-neutrino to neutrino flux ratio is . The absolute rates and distributions observed are shown to be in quantitative agreement with the known properties of charmedquark production in hadron collisions.Supported by the Bundesministerium für Forschung und Technologic, Bonn, FRG