Incident-angle dependence of deformation characteristics of aluminum surface under low-energy xenon-ion impact

Ion thruster is a revolution technology with potential applications in space mission but the thrusters operation lifetime is limited by the sputtering from thruster components. In this work, molecular dynamic simulations are performed to explore the dependence of deformation characteristics of an aluminum surface on incident angle and kinetic energy under low-energy xenon-ion impact. The fraction of non-12-coordinated atoms is used to quantitatively characterize the microstructural evolution and defect density levels. It is found that defect density level has a linear relation with incident energy, and there exists a critical incident angle around 20 degrees, at which the aluminum surface has the maximum defect density level. In addition, a collision model is developed to theoretically reveal the physical mechanisms behind the dependence. Our findings may helpful in developing long endurance electric propulsion devices for practical applications.Comment: 21 pages, 8 figure

Thermosensitive Nanocables Prepared by Surface-Initiated Atom Transfer Radical Polymerization

Thermosensitive nanocables consisting of Au nanowire cores and poly(N-isopropylacrylamide) sheaths (denoted as Au/PNIPAAm) were synthesized by surface-initiated atom transfer radical polymerization (SI-ATRP). The formation of PNIPAAm sheath was verified by Fourier transform infrared (FTIR) and hydrogen nuclear magnetic resonance (1H NMR) spectroscopy. Transmission electron microscope (TEM) results confirmed the core/shell structure of nanohybrids. The thickness and density of PNIPAAm sheaths can be adjusted by controlling the amount of cross-linker during the polymerization. Signature temperature response was observed from Au/cross-linked-PNIPAAm nanocables. Such smart nanocables show immense potentials as building blocks for novel thermosensitive nanodevices in future

Solving Huge Gyroscopic Eigenproblems With AMLS and Subspace Iteration

The Automated Multilevel Sub-structuring (AMLS) method is a powerful technique for computing a large number of eigenpairs with moderate accuracy for huge definite eigenvalue problems in structural analysis. It also turned out to be a useful tool to construct a suitable ansatz space for orthogonal projection methods for gyroscopic problems. This paper takes advantage of information gained from AMLS to improve the obtained eigenpairs via a small number of subspace iteration steps. Copyright ? 2012 by ASME.EI

Modal Analysis Comparison of Beam and Shell Models for Composite Blades

The composite blades of wind turbines are made up of composite shell components. However, blades are often simplified as Eulerian beam in finite element analysis. In design both special and general purpose finite element codes are used worldwide. The verification of a special finite element code BModes vs. a popular general purpose finite element code ANSYS are performed via a uniform blade in both still and spinning cases in this paper. The test reveals that general finite element codes like ANSYS might overestimate the lag frequencies in spinning case. After verification of beam model, the approach is applied to complete the modal analysis of a practical wind turbine blade. The results are compared with a known shell model from literature. The comparison validates the simplified Eulerian beam model. Finally a guideline of usage for these two models is given.http://gateway.webofknowledge.com/gateway/Gateway.cgi?GWVersion=2&SrcApp=PARTNER_APP&SrcAuth=LinksAMR&KeyUT=WOS:000270497300200&DestLinkType=FullRecord&DestApp=ALL_WOS&UsrCustomerID=8e1609b174ce4e31116a60747a720701Energy & FuelsCPCI-S(ISTP)

Emergence and Transfer of Plasmid-Harbored <i>rmtB</i> in a Clinical Multidrug-Resistant <i>Pseudomonas aeruginosa</i> Strain

Multidrug-resistant (MDR) Pseudomonas aeruginosa poses a great challenge to clinical treatment. In this study, we characterized a ST768 MDR P. aeruginosa strain, Pa150, that was isolated from a diabetic foot patient. The minimum inhibitory concentration (MIC) assay showed that Pa150 was resistant to almost all kinds of antibiotics, especially aminoglycosides. Whole genome sequencing revealed multiple antibiotic resistant genes on the chromosome and a 437-Kb plasmid (named pTJPa150) that harbors conjugation-related genes. A conjugation assay verified its self-transmissibility. On the pTJPa150 plasmid, we identified a 16S rRNA methylase gene, rmtB, that is flanked by mobile genetic elements (MGEs). The transfer of the pTJPa150 plasmid or the cloning of the rmtB gene into the reference strain, PAO1, significantly increased the bacterial resistance to aminoglycoside antibiotics. To the best of our knowledge, this is the first report of an rmtB-carrying conjugative plasmid isolated from P. aeruginosa, revealing a novel possible transmission mechanism of the rmtB gene

METTL3-dependent m6A methylation facilitates uterine receptivity and female fertility via balancing estrogen and progesterone signaling

Abstract Infertility is a worldwide reproductive health problem and there are still many unknown etiologies of infertility. In recent years, increasing evidence emerged and confirmed that epigenetic regulation played a leading role in reproduction. However, the function of m6A modification in infertility remains unknown. Here we report that METTL3-dependent m6A methylation plays an essential role in female fertility via balancing the estrogen and progesterone signaling. Analysis of GEO datasets reveal a significant downregulation of METTL3 expression in the uterus of infertile women with endometriosis or recurrent implantation failure. Conditional deletion of Mettl3 in female reproductive tract by using a Pgr-Cre driver results in infertility due to compromised uterine endometrium receptivity and decidualization. m6A-seq analysis of the uterus identifies the 3’UTR of several estrogen-responsive genes with METTL3-dependent m6A modification, like Elf3 and Celsr2, whose mRNAs become more stable upon Mettl3 depletion. However, the decreased expression levels of PR and its target genes, including Myc, in the endometrium of Mettl3 cKO mice indicate a deficiency in progesterone responsiveness. In vitro, Myc overexpression could partially compensate for uterine decidualization failure caused by Mettl3 deficiency. Collectively, this study reveals the role of METTL3-dependent m6A modification in female fertility and provides insight into the pathology of infertility and pregnancy management