Thermolysis reaction of 2-acetyl-1-oxo-five-, six-, and seven-membered ring

The rates of gas-phase thermolysis reactions of 2-acetylcyclopentanone 1,2-acetylcyclohexanone 2, N-acetylcaprolactam 3,2-acetylbutyrolactone 4,2-acetyl-2-methylbutyrolactone 5, and 3-acetyl-2-oxazolidinone 6 have been measured over a temperature range of 50 K. They undergo unimolecular first-order elimination reactions for which log A = 11.7, 11.7, 11.2, 11.4, 11.5, and 11.1 s^?1 and E_a = 193.4, 189.5, 153.2, 201.0, 206.8, and 176.1 kJ mol^?1, respectively. The effect of the ring size together with the effect of a heteroatom in the ring on the rate of thermolysis reactions for compound 1–6 is the subject of this work. © 1995 John Wiley & Sons, Inc.     

Running of neutrino parameters and the Higgs self-coupling in a six-dimensional UED model

We investigate a six-dimensional universal extra-dimensional model in the extension of an effective neutrino mass operator. We derive the β  -functions and renormalization group equations for the Yukawa couplings, the Higgs self-coupling, and the effective neutrino mass operator in this model. Especially, we focus on the renormalization group running of physical parameters such as the Higgs self-coupling and the leptonic mixing angles. The recent measurements of the Higgs boson mass by the ATLAS and CMS Collaborations at the LHC as well as the current three-flavor global fits of neutrino oscillation data have been taken into account. We set a bound on the six-dimensional model, using the vacuum stability criterion, that allows five Kaluza–Klein modes only, which leads to a strong limit on the cutoff scale. Furthermore, we find that the leptonic mixing angle _θ12${\theta }_{12}$ shows the most sizeable running, and that the running of the angles _θ13${\theta }_{13}$ and _θ23${\theta }_{23}$ are negligible. Finally, it turns out that the findings in this six-dimensional model are comparable with what is achieved in the corresponding five-dimensional model, but the cutoff scale is significantly smaller, which means that it could be detectable in a closer future.     

Delayed bifurcations and negative hysteresis in semiconductor lasers: the role of initial conditions

The dynamical intensity response of a semiconductor laser under the influence of injection current modulation, and the resulting hysteresis behavior, is investigated experimentally and theoretically. We report the first experimental observation, in a semiconductor laser, of the transition from a negative to a positive hysteresis as the modulation frequency of the injection current is varied. The theoretical work isolates the initial conditions on the intrinsic laser parameters as the sole determinant in influencing the kind of hysteresis one observes.     

Structure-activity relationships for apomorphine congeners. Conformational energies vs. biological activities

Summary A series of apomorphine congeners has been studied with respect to their ability to mimic the structural requirements of the dopamine pharmacophore in the potent and stereoselective dopamine receptor agonist (R)-apomorphine. Conformational energies of the mimicking structures calculated by molecular mechanics (MMP2) correlate well with the observed biological activities.     

ELENA: the extra low energy anti-proton facility at CERN

At the last LEAP conference in Vancouver 2011 the authors stated that a project ”ELENA”, as an abbreviation for Extra Low ENergy Antiproton ring and as first discussed in 1982 for LEAR by H. Herr et al., was freshly proposed with a substantial new design and revised layout and that it was under consideration to be built at CERN. ELENA is an upgrade of the Anti-proton Decelerator (AD) at CERN and is devoted to special experiments with physics using low energy anti-protons. The main topics are the anti-hydrogen production and consecutive studies of the features of this anti-matter atom as well as the anti-proton nucleon interaction by testing the QED to high precision. During the last years the project underwent several steps in presentations at different committees at CERN and was finally approved such that the construction has started. ELENA will increase the number of useful anti-protons by about two orders of magnitude and will allow to serve up to four experiments simultaneously. Very first and convincing results from the experiments at the AD have been published recently. For high precision physics, however, it appears to be cumbersome, time consuming and ineffective when collecting the needed large numbers and high densities of anti-proton clouds with the present AD. Both the effectiveness and the availability for additional experiments at this unique facility will drastically increase, when the anti-proton beam of presently 5 MeV kinetic energy is reduced by the additional decelerator ELENA to 100 keV.     

Horse heart cytochrome c entrapped into the hydrated liquid-crystalline phases of phytantriol: X-ray diffraction and Raman spectroscopic characterization

Small angle X-ray diffraction (SAXD), resonance Raman (RR) spectroscopy with 413 nm excitation, and non-resonance Raman technique with 785 nm excitation were used to probe the influence of entrapped cytochrome c (Cyt c) on the structure of hydrated phytantriol (Phyt) liquid-crystalline phases as well as conformational changes of heme group and secondary structure of the protein. SAXD measurements indicated that incorporation of Cyt c affects both nanostructure dimensions and type of liquid-crystalline phases of hydrated Phyt. The unit cell dimensions decrease with increasing Cyt c concentration for all phases. In addition, protein perturbs the nanostructure of Q(230) and Q(224) liquid-crystalline phases of hydrated Phyt to such an extent that they transform into the Q(229) phase with the Im3m space group. RR data revealed that entrapment of oxidized Cyt c into the Q(230) phase at 1 wt.% content results in near complete reduction of central iron ion of the heme group, while its low-spin state and six-ligand coordination configuration are preserved. Based on the analysis of heme out-of-plane folding vibration near 568 cm(-1) (γ(21)) and ν(48) mode at 633 cm(-1), it was demonstrated that the protein matrix tension on the heme group is relaxed upon incorporation of protein into Q(230) phase. Non-resonant Raman bands of difference spectra showed the preservation of α-helix secondary structure of Cyt c in the liquid-crystalline phase at relatively high (5 wt.%) content. The Cyt c induced spectroscopic changes of Phyt bands were found to be similar as decrease in temperature.