Temperature dependence of self-broadening in molecular-oxygen spectrum

Summary The ^p P(k=9) magnetic-dipole transition of the oxygen 0-0 vibrational band of the red systemb ¹Σ _g ⁺ ←X ³Σ _g ⁻ was observed with absorption spectroscopy using a tunable CW diode laser. A systematic investigation of the self-collisional broadening was performed for different gas pressures and temperatures. The temperature dependence of the self-broadening coefficient was determined to beT ^{−(1.02±0.05)}. Our results are of interest for collisional theory and as reference data in atmospheric monitoring applications. The authors of this paper have agreed to not receive the proofs for correction.     

Redox-Flow Batteries: From Metals to Organic Redox-Active Materials

Research on redox-flow batteries (RFBs) is currently experiencing a significant upturn, stimulated by the growing need to store increasing quantities of sustainably generated electrical energy. RFBs are promising candidates for the creation of smart grids, particularly when combined with photovoltaics and wind farms. To achieve the goal of “green”, safe, and cost-efficient energy storage, research has shifted from metal-based materials to organic active materials in recent years. This Review presents an overview of various flow-battery systems. Relevant studies concerning their history are discussed as well as their development over the last few years from the classical inorganic, to organic/inorganic, to RFBs with organic redox-active cathode and anode materials. Available technologies are analyzed in terms of their technical, economic, and environmental aspects; the advantages and limitations of these systems are also discussed. Further technological challenges and prospective research possibilities are highlighted.     

Effect of the β-propiolactone treatment on the adsorption and fusion of influenza A/Brisbane/59/2007 and A/New Caledonia/20/1999 virus H1N1 on a dimyristoylphosphatidylcholine/ganglioside GM3 mixed phospholipids monolayer at the air-water interface

The production protocol of many whole cell/virion vaccines involves an inactivation step with β-propiolactone (BPL). Despite the widespread use of BPL, its mechanism of action is poorly understood. Earlier work demonstrated that BPL alkylates nucleotide bases, but its interaction with proteins has not been studied in depth. In the present study we use ellipsometry to analyze the influence of BPL treatment of two H1N1 influenza strains, A/Brisbane/59/2007 and A/New Caledonia/20/1999, which are used for vaccine production on an industrial scale. Analyses were conducted using a mixed lipid monolayer containing ganglioside GM3, which functions as the viral receptor. Our results show that BPL treatment of both strains reduces viral affinity for the mixed monolayer and also diminishes the capacity of viral domains to self-assemble. In another series of experiments, the pH of the subphase was reduced from 7.4 to 5 to provoke the pH-induced conformational change of hemagglutinin, which occurs following endocytosis into the endosome. In the presence of the native virus the pH decrease caused a reduction in domain size, whereas lipid layer thickness and surface pressure were increased. These observations are consistent with a fusion of the viral membrane with the lipid monolayer. Importantly, this fusion was not observed with adsorbed inactivated virus, which indicates that BPL treatment inhibits the first step of virus-membrane fusion. Our data also indicate that BPL chemically modifies hemagglutinin, which mediates the interaction with GM3.     

Coherent delocalization of atomic wave packets in driven lattice potentials

Atomic wave packets loaded into a phase-modulated vertical optical-lattice potential exhibit a coherent delocalization dynamics arising from intraband transitions among Wannier-Stark levels. Wannier-Stark intraband transitions are here observed by monitoring the in situ wave-packet extent. By varying the modulation frequency, we find resonances at integer multiples of the Bloch frequency. The resonances show a Fourier-limited width for interrogation times up to 2 s. This can also be used to determine the gravity acceleration with ppm resolution.     

Doppler-free spectroscopy using magnetically induced dichroism of atomic vapor: a new scheme for laser frequency locking

We demonstrate a Doppler-free spectroscopic method that we test on ⁸⁷Rb and ⁸⁵Rb vapor. By using a magnetic field to induce a dichroism on the sample, we generate a dispersive signal with low background, which allows us to lock a diode laser even on small spectroscopic features. We elaborate the advantages of this simple and easy method by comparing it to other methods. Received 15 October 2002 Published online 17 December 2002     

Langevin equation approach to granular flow in a narrow pipe

The gravity-driven flow of granular material through a rough, narrow vertical pipe is described using the Langevin equation formalism. Above a critical particle density the homogeneous flow becomes unstable with respect to short-wave length perturbations. In correspondence with experimental observations, we find clogging and density waves in the flowing material.     

Axially symmetric hollow beams using refractive conical lenses

We explore the possibility of producing several beam shapes with conical or cylindrical geometry using conical lenses. We discuss optical schemes for generation of hollow laser beams; with 3D intensity distribution surrounding all directions, a dark core region can be obtained. These optical fields are important for the confinement of cold atoms in 2D or 3D blue dipole potentials.     

Proposed search for small violations of bose statistics in molecular spectra

Summary I discuss the possibility of performing a test of the symmetrization postulate for bosons by high-sensitivity spectroscopy of¹⁶O₂. I show that the sensitivity required to give significant information can be easily achieved by well-developed spectroscopic methods. The author of this paper has agreed to not receive the proofs for correction     

High resolution spectroscopy of iridium in a hollow cathode discharge

We demonstrate the possibility of performing high resolution laser spectroscopy of iridium atoms produced by sputtering in a hollow cathode discharge. By resolving the hyperfine structure of ultraviolet transitions from the ground state, we measure the magnetic dipole and electric quadrupole constants of the 5d ⁷ 6s 6p ⁶ G _11/2 and 5d ⁷ 6s 6p ⁶ F _7/2 excited levels and we obtain accurate values for the isotope shifts. Iridium is also discussed as possibly providing reference spectra in the 243 nm region, close to the wavelength of the 1s–2s two-photon transition of hydrogen.     

Indices de rétention de cycloalcanes,cycloalcènes,bicycloalkyles, cycloalkyl-cycloalcényles et bicycloalcényles en chromatographie en phase gazeuse

The retention indices for cycloalkanes, cycloalkenes and bicyclic compounds have been measured as a function of temperature for different liquids phases. The diastereomeric bicycloalkenyl-2 were separated. Some rules concerning the indices are given.