Ultra-hard low friction coating based on A1MgB14 for reduced wear of MEMS and other tribological components and system

Performance and reliability of microelectromechanical system (MEMS) components enhanced dramatically through the incorporation of protective thin film coatings. Current-generation MEMS devices prepared by the LIGA technique employ transition metals such as Ni, Cu, Fe, or alloys thereof, and hence lack stability in oxidizing, corrosive, and/or high temperature environments. Fabrication of a superhard, self-lubricating coating based on a ternary boride compound AlMgB14 is described in this letter as a potential breakthrough in protective coating technology for LIGA microdevices. Nanoindentation tests show that hardness of AlMgB14 films prepared by pulsed laser deposition ranges from 45 GPa to 51 GPa, when deposited at room temperature and 573 K, respectively. Extremely low friction coefficients of 0.04-0.05, which are thought to result from a self-lubricating effect, have also been confirmed by nanoscratch tests on the AlMgB14 films. Transmission electron microscopy studies show that the as-deposited films are amorphous, regardless of substrate temperature; however, analysis of FTIR spectra suggests that the higher substrate temperature facilitates formation of the B12 icosahedral framework, therefore leading to the higher hardness

Microstructure evolution of Al–Mg–B thin films by thermal annealing

The growth of Al–Mg–B thin films on SiO2/Si(100) substrates was performed by nanosecond pulsed laser deposition at three different substrate temperatures (300 K, 573 K, and 873 K). The as-deposited films were then annealed at 1173 K or 1273 K for 2 h. X-ray photoelectron spectroscopy,x-ray diffraction(XRD), and atomic force microscope were employed to investigate the effects of processing conditions on the composition, microstructure evolution, and surface morphology of the Al–Mg–B films. The substrate temperatures were found to affect the composition of as-deposited films in that the Mg content decreases and C content increases at higher substrate temperatures, in particular for the 873 K-deposited film.XRD results show that the as-deposited films were amorphous, and this structure may be stable up to 1173 K. Annealing at 1273 K was found to fully crystallize the room temperature and 573 K-deposited Al–Mg–B films with the formation of the polycrystalline orthorhombic AlMgB14 phase, accompanied by the development of a pronounced (011) preferred orientation. Nevertheless, high C incorporation in the 873 K-deposited Al–Mg–B film inhibits the crystallization and the amorphous structure remains stable even during 1273 K annealing. The presence of Si in the room-temperature-deposited 1273 K-annealed film due to the interdiffusion between the substrate and film leads to the formation of an additional tetragonal α-FeSi2 phase, which is thought to cause the surface cracking and microstructural instability observed in this film

Electrical transport in amorphous semiconducting AlMgB14 films

The electrical transport properties of semiconducting AlMgB14films deposited at room temperature and 573K are reported in this letter. The as-deposited films are amorphous, and they exhibit high n-type electrical conductivity, which is believed to stem from the conduction electrons donated by Al, Mg, and/or Fe impurities in these films. The film deposited at 573K is less conductive than the room-temperature-deposited film. This is attributed to the nature of donor or trap states in the band gap related to the different deposition temperatures

Rigor Mortis: Annotating MWEs with a Gamified Platform

International audienceWe present here Rigor Mortis, a gamified crowdsourcing platform designed to evaluate the intuition of the speakers, then train them to annotate multi-word expressions (MWEs) in French corpora. We previously showed (Fort et al., 2018) that the speakers' intuition is reasonably good (65% in recall on non-fixed MWE). After a training phase using some of the tests developed in the PARSEME-FR project, we obtain 0.685 in F-measure at an experimentally determined 25% threshold (number of players who annotated the same segment)

VBP15, a glucocorticoid analogue, is effective at reducing allergic lung inflammation in mice

Asthma is a chronic inflammatory condition of the lower respiratory tract associated with airway hyperreactivity and mucus obstruction in which a majority of cases are due to an allergic response to environmental allergens. Glucocorticoids such as prednisone have been standard treatment for many inflammatory diseases for the past 60 years. However, despite their effectiveness, long-term treatment is often limited by adverse side effects believed to be caused by glucocorticoid receptor-mediated gene transcription. This has led to the pursuit of compounds that retain the anti-inflammatory properties yet lack the adverse side effects associated with traditional glucocorticoids. We have developed a novel series of steroidal analogues (VBP compounds) that have been previously shown to maintain anti-inflammatory properties such as NFκB-inhibition without inducing glucocorticoid receptor-mediated gene transcription. This study was undertaken to determine the effectiveness of the lead compound, VBP15, in a mouse model of allergic lung inflammation. We show that VBP15 is as effective as the traditional glucocorticoid, prednisolone, at reducing three major hallmarks of lung inflammation--NFκB activity, leukocyte degranulation, and pro-inflammatory cytokine release from human bronchial epithelial cells obtained from patients with asthma. Moreover, we found that VBP15 is capable of reducing inflammation of the lung in vivo to an extent similar to that of prednisone. We found that prednisolone--but not VBP15 shortens the tibia in mice upon a 5 week treatment regimen suggesting effective dissociation of side effects from efficacy. These findings suggest that VBP15 may represent a potent and safer alternative to traditional glucocorticoids in the treatment of asthma and other inflammatory diseases.Supported in part by grants from the NIH (1R41HL104939-01B; 1K26RR032082; 1P50AR060836-01; 1U54HD071601; 2R24HD050846-06, R01 HL033152- 25), DOD grants (W81XWH-11-1-0330; W81XWH-11-1-0782; W81XWH-10-1-0659; W81XWH-11-1-0809; W81XWH-09-1-0599) a translational research grant from MDA, pilot grant from Parent Project Muscular Dystrophy (PPMD), and a contribution from the Clark Family Foundation

Integrin-mediated axoglial interactions initiate myelination in the central nervous system

All but the smallest-diameter axons in the central nervous system are myelinated, but the signals that initiate myelination are unknown. Our prior work has shown that integrin signaling forms part of the cell–cell interactions that ensure only those oligodendrocytes contacting axons survive. Here, therefore, we have asked whether integrins regulate the interactions that lead to myelination. Using homologous recombination to insert a single-copy transgene into the hypoxanthine phosphoribosyl transferase (hprt) locus, we find that mice expressing a dominant-negative β1 integrin in myelinating oligodendrocytes require a larger axon diameter to initiate timely myelination. Mice with a conditional deletion of focal adhesion kinase (a signaling molecule activated by integrins) exhibit a similar phenotype. Conversely, transgenic mice expressing dominant-negative β3 integrin in oligodendrocytes display no myelination abnormalities. We conclude that β1 integrin plays a key role in the axoglial interactions that sense axon size and initiate myelination, such that loss of integrin signaling leads to a delay in myelination of small-diameter axons