Matrix solution fixation: histology-compatible tissue preparation for MALDI mass spectrometry imaging

Mass spectrometry imaging (MSI) acquires a grid of spatially resolved mass spectra and provides a molecular landscape of a tissue. This can have a myriad of uses: from basic tissue characterization to a comprehensive pathological diagnosis. We have developed a fast, inexpensive, histology-compatible tissue preparation method for matrix-assisted laser desorption/ionization (MALDI)-MSI, which overcomes current sample preparation-imposed limitations in image resolution. Tissue sections are prepared via simultaneous fixation and matrix deposition. This is accomplished by incorporating the MALDI matrix into solvents that preserve tissue integrity when applied according to standard histology procedures. This concept was expanded to include multiple histology protocols, thereby enabling analysis to be tailored to a variety of biomolecules and tissue types.     

Magnetron Sputtering Deposition of Ag/TiO2 Nanocomposite Thin Films for Repeatable and Multicolor Photochromic Applications on Flexible Substrates

It is reported on a reactive magnetron sputtering‐based deposition method to synthesize, at room temperature, photochromic nanocomposite thin films consisting of Ag nanoparticles sandwiched between nanoporous TiO₂ layers. The fabrication process is compatible with large‐scale production and functional flexible substrates. It is shown that when TiO₂ is deposited in the metallic mode, the formation of Ag metal nanoparticles induces localized surface plasmon resonances in the visible range and therefore the as‐deposited samples are colored. In contrast, when TiO₂ is deposited in the compound mode, the trilayer samples are colorless because silver oxidizes during TiO₂ deposition. It is demonstrated that the colorless samples can be colored under ultraviolet (UV) laser exposure at 244 nm due to the reduction of oxidized silver and the formation of metallic Ag nanoparticles. Moreover, irradiation at 647 nm wavelength of colored samples (as‐prepared or after UV exposure) gives rise to changes in the particle morphology that strongly modifies the film absorbance and results in a color transition from blue to orange. The choice of the irradiation wavelength allows controlling the color saturation of the sample up to the complete discoloration by using a visible laser at 488 nm. All these photochromic mechanisms are repeatable during cyclic processes.     

Analysis of the diffractional properties of dual-period apodizing gratings: theoretical and experimental results

We present an analysis of the diffractional properties of dual-period apodizing gratings. In a previous paper we used these components to obtain single-lateral-mode and dual-longitudinal-mode emission from a broad-area diode laser. We now calculate the diffracted field for a monochromatic beam incident on the grating by using an analytical model. Predictions of the model are compared with experimental measurements made with several dual-period gratings. We also discuss the situation in which a dual-period grating is used as an external coupler of a diode laser in a two-wavelength emission regime.     

Microstructural development during transient directional solidification of hypermonotectic Al–Bi alloys

Directional unsteady-state solidification experiments were performed with hypermonotectic Al–5.0 wt%Bi and 7.0 wt%Bi alloys. Thermal parameters such as the growth rate (v) and the thermal gradient (G) were experimentally determined by cooling curves recorded along the casting length. The predominant Bi-rich phase was characterized by droplets embedded in the aluminum matrix. Both the interphase spacing (λ) and the Bi-rich particles diameter (d) were measured along the casting length. These microstructural features were correlated to the solidification thermal parameters: growth rate, cooling rate and thermal gradient. An experimental law expressing λ as a function of both G and v was found to better represent the growth of hypermonotectic Al–Bi alloys. Moreover, it was found that the interphase spacing decreases with increasing alloy bismuth content.     

Evaluation of models for tube material characterization with the tube bulging test in an industrial setting

It is now well recognized that the material data obtained from a tensile test is less appropriate than those from a Tube Bulging Test (TBT) for a finite element simulation of tube hydroforming. However, the manufacturers still use classical data (often tensile test data) for designing metal operations due to the lack of standard for the TBT and a more complex post processing analysis of experimental measures. Getting the hardening curve from the tube bulging test requires the use of an analytical or numerical model. In this paper, three models for post-processing measures obtained from the TBT are compared based on the same experimental procedure. Thanks to a preliminary step, consisting of the validation of the analytical models through the use of finite element simulations of the TBT, it highlights that the results obtained for the local (stress and strain) and global components (the thickness distribution along the tube and the deformed tube profile) are very close, whatever the models. The test configuration (die radius and free length) seems to have no significant impact on the resulting stress-strain curve for the three models. The three models are used for post processing tube bulging tests performed on AISI304, INCONEL and Copper tubes validating their capacity for tube characterization on different materials. Finally, this study demonstrates that the Boudeau-Malécot Model can be used to obtain hardening curve from TBT without a loss of accuracy compared to more complex post-processing models and with an important gain of quality compared to tensile test.     

Two-photon excitation fluorescence microscopy with a high depth of field using an axicon

In conventional two-photon excitation fluorescence microscopy, the numerical aperture of the objective determines the lateral resolution and the depth of field. In some situations, as with functional imaging of dynamic events distributed in live biological tissue, an improved temporal resolution is needed; as a consequence, it is imperative to use optics with a high depth of field to simultaneously image objects at different axial positions. With a conventional microscope objective, increasing the depth of field is achieved at the expense of lateral resolution. To overcome this limitation, we have incorporated an axicon in a two-photon excitation fluorescence microscopy system; measurements have shown that an axicon provides a depth of field in excess of a millimeter, while the lateral resolution is maintained at the micrometer scale. Thus axicon-based two-photon microscopy has been shown to yield a high-resolution projection image of a sample with a single 2D scan of the laser beam while maintaining the improved tissue penetration typical of two-photon microscopy.     

Self-reported road traffic violations in France and how they have changed since 1983

Goals

The goal was to gain a picture of current driver behaviour, and of the links between committed violations and accident history. It was also to identify how driver behaviour has changed over the last 20 years.

Methods

A questionnaire-based cross-sectional study of a sample of 1161 drivers about the frequency of violations and the perception of the dangers and penalties associated with them was used in 2005. Self-reported violations and mental representations were also compared to the results of Biecheler who used similar methods (Biecheler-Fretel, 1983).

Results, conclusions

Road traffic violations are frequent in France, particularly among male drivers. Several violations are linked with history of accidents in our sample. Frequently or fairly frequently exceeding the speed limit by 10 km/h (a violation reported by almost 53% of our sample), increases accident occurrence by a factor of 1.4. Progress in drivers’ behaviour has been slow and nonuniform, and appears in part to be related to safety campaigns that have been run (seat belts, alcohol). The results could inform future campaigns. In particular, a campaign on the use of indicators would seem worthwhile.     

Hydrodynamic dispersion in shallow microchannels: the effect of cross-sectional shape

We highlight the fact that hydrodynamic dispersion in shallow microchannels is in most cases controlled by the width of the cross section rather than by the much thinner height of the channel. We identify the relevant time scales that separate the various regimes involved. Using the lubrication approximation, we provide simple formulas that permit a quantitative evaluation of dispersion for most shallow cross-sectional shapes in the "long-time" Taylor regime, which is effectively diffusive. Because of its relevance for microfluidic systems, we also provide results for the short-time "ballistic regime" (for specific initial conditions). The special cases of parabolic and quasi-rectangular shapes are considered due to their frequent use in microsystems.     

Electroleaching and electrodeposition of zinc in a single-cell process for the treatment of solid waste

This work deals with zinc beneficiation of industrial solid waste by an electrochemical technique combining electroleaching and electrodeposition in a single-cell process. This technique is based on leaching of the solid waste by the protons generated at the anode and migration of the resulting ions toward the cathode where deposition takes place. A laboratory cell was built for testing the method. It consisted of three compartments, two electrode compartments and a solid waste chamber placed between these. Catholyte and anolyte were sulphuric/sulphate solutions at optimised concentrations. Experiments were first carried out using a zinc solution and an inert matrix in the central compartment, then using a synthetic waste prepared by dispersing zinc oxide in silicon dioxide. Best performance was obtained with treatment duration of 6h, at 4.5Adm(-2) and with catholyte circulation. In this case, a 97% of zinc oxide lixiviation and 75% of zinc-plated were achieved.