Long pulse electron beam excited XeF laser

Long pulse operation of the XeF laser has been achieved with a short gain length and medium intensity electron beam excitation for both Ar/Xe/NF₃ and Ne/Xe/NF₃ mixtures. Use of Ne as diluant strongly lower the threshold for lasing and give an important increase in extracted power. For a total mixture pressure of 2 atm about 6 mJ of 3500 Å radiation was obtained in a 400 ns fwhm pulse limited only by e-beam pulse length.     

Measurement of large transverse momentum positive particles produced at medium angles at √s = 52.5 GeV

The inclusive spectrum of positive particles has been measured at the ISR energy √s = 52.5 GeV as function of transverse momentum, p_T for large p_T values using the Split Field Magnet facility. The angular dependence of the distribution is observed and discussed in the range $\text{9° ? θ}{}^1\text{? 21°}$. An upper limit for the production of ? meson with p_T ? 3 GeV/c is derived from the same sample of data.     

32 Phase X 32 amplitude optical arbitrary waveform generation

We describe the precise shaping and mode-resolved amplitude and phase characterization of optical arbitrary waveforms by using a 20 GHz optical frequency comb and integrated 64 x 20 GHz channel arrayed waveguide grating pair. Complex waveforms with large variations in phase and amplitude between adjacent modes were generated and characterized.     

Bioluminescence is produced from a trapped firefly luciferase conformation predicted by the domain alternation mechanism

According to the domain alternation mechanism and crystal structure evidence, the acyl-CoA synthetases, one of three subgroups of a superfamily of adenylating enzymes, catalyze adenylate- and thioester-forming half-reactions in two different conformations. The enzymes accomplish this by presenting two active sites through an ~140° rotation of the C-domain. The second half-reaction catalyzed by another subgroup, the beetle luciferases, is a mechanistically dissimilar oxidative process that produces bioluminescence. We have demonstrated that a firefly luciferase variant containing cysteine residues at positions 108 and 447 can be intramolecularly cross-linked by 1,2-bis(maleimido)ethane, trapping the enzyme in a C-domain-rotated conformation previously undocumented in the available luciferase crystal structures. The cross-linked luciferase cannot adenylate luciferin but is nearly fully capable of bioluminescence with synthetic luciferyl adenylate because it retains the ability to carry out the oxidative half-reaction. The cross-linked luciferase is apparently trapped in a conformation similar to those adopted by acyl-CoA synthetases as they convert acyl adenylates into the corresponding CoA thioesters.     

Nonlinear friction dynamics on fibrous materials, application to the characterization of surface quality. Part?II: local characterization of phase space by recurrence plots

As has been shown in the first part of this series of papers, the global analysis of phase spaces does not allow one to access topographies of attractors, generated by the singular dynamic contacts between MODALSENS and our evaluated fibrous surfaces. By using the same time series from MODALSENS, this second paper presents a local exploration of the recurrences of the phase spaces. As a complement of the results from Part I, we propose, in this part of the work, a finer analysis of the vibrations of MODALSENS. Therefore, this part of the work aims at tracing friction dynamics cartographies of fibrous surfaces with the help of Recurrence Plots. This tool allows one to obtain images of recurrences in the space portraits. Hence, by regarding passages between strong and low magnitudes of vibrations, it is possible to take into account strong heterogeneities of relief and also the various mechanical and frictional behaviors of the asperities encountered during friction. Finally, Recurrence Quantification Analysis is performed in order to discuss the relationship between expected performances of the tested surfaces and their friction dynamics behaviors.     

3D displacement field measurement with correlation based on the micro-geometrical surface texture

Image correlation methods are widely used in experimental mechanics to obtain displacement field measurements. Currently, these methods are applied using digital images of the initial and deformed surfaces sprayed with black or white paint. Speckle patterns are then captured and the correlation is performed with a high degree of accuracy to an order of 0.01 pixels. In 3D, however, stereo-correlation leads to a lower degree of accuracy. Correlation techniques are based on the search for a sub-image (or pattern) displacement field. The work presented in this paper introduces a new correlation-based approach for 3D displacement field measurement that uses an additional 3D laser scanner and a CMM (Coordinate Measurement Machine). Unlike most existing methods that require the presence of markers on the observed object (such as black speckle, grids or random patterns), this approach relies solely on micro-geometrical surface textures such as waviness, roughness and aperiodic random defects. The latter are assumed to remain sufficiently small thus providing an adequate estimate of the particle displacement. The proposed approach can be used in a wide range of applications such as sheet metal forming with large strains. The method proceeds by first obtaining cloud points using the 3D laser scanner mounted on a CMM. These points are used to create 2D maps that are then correlated. In this respect, various criteria have been investigated for creating maps consisting of patterns, which facilitate the correlation procedure. Once the maps are created, the correlation between both configurations (initial and moved) is carried out using traditional methods developed for field measurements. Measurement validation was conducted using experiments in 2D and 3D with good results for rigid displacements in 2D, 3D and 2D rotations.     

Fourier-transform, integrated-optic spatial heterodyne spectrometer on a silica-based planar waveguide with 1 GHz resolution

Spatial heterodyne spectrometers (SHS) can achieve high resolution with excellent optical throughput. We demonstrate a planar waveguide SHS incorporating 64 asymmetric Mach-Zehnder interferometers and show measurements that verify 1 GHz resolution across a 64 GHz measurement range.     

Thermotropic Luminescent Clustomesogen Showing a Nematic Phase: A Combination of Experimental and Molecular Simulation Studies

Octahedral Mo₆ nanoclusters are functionalized with two organic ligands containing cyanobiphenyl (CB) units, giving luminescent hybrid liquid crystals (LC). Although the mesogenic density around the bulky inorganic core is constant, the two hybrids show different LC properties. Interestingly, one of them shows a nematic phase, which is particularly rare for this kind of supermolecular system. This surprising result is explained by using large‐scale molecular dynamic simulations.