Response and performance of a nonlinear vibration isolator with high-static-low-dynamic-stiffness under shock excitations

A nonlinear vibration isolator with High-Static-Low-Dynamic-Stiffness (HSLDS) characteristic comprised of vertical spring and horizontal spring is presented in this paper. Response of the nonlinear vibration isolator under three different kinds of base shock excitations is considered, the dynamic motion can be approximately described by the classic Duffing equation. A transformation function and ultra-spherical polynomial approximation method are employed to determine the shock response and compared with numerical method. Then performance of the nonlinear vibration isolator under shock excitations is evaluated by three performance indicies (Maximum Absolute Displacement Ratio (MADR), Maximum Relative Displacement Ratio (MRDR) and Maximum Acceleration Ratio (MAR)), and also compared with a linear one. Results show that the analytic method suits for weak nonlinearity and the performance of the nonlinear vibration isolator under shock excitations is greatly influenced by the input shock magnitude and structural parameters

Using Mendelian randomization analysis to determine the causal connection between unpleasant emotions and coronary atherosclerosis

ObjectiveObservational studies have shown a correlation between unpleasant emotions and coronary atherosclerosis, but the underlying causal linkages are still uncertain. We conducted a Mendelian randomization (MR) investigation on two samples for this purpose.MethodsIn genome-wide association studies in the UK Biobank (total = 459,561), we selected 40 distinct single-nucleotide polymorphisms (SNPs) related to unpleasant emotions as genome-wide statistically significant instrumental variables. FinnGen consortium provided summary-level data on coronary atherosclerosis for 211,203 individuals of Finnish descent. MR-Egger regression, the inverse variance weighted technique (IVW), and the weighted median method were used in the process of conducting data analysis.ResultsThere was sufficient evidence to establish a causal connection between unpleasant emotions and coronary atherosclerosis risk. For each unit increase in the log-odds ratio of unpleasant feelings, the odds ratios were 3.61 (95% CI: 1.64–7.95; P = 0.001). The outcomes of sensitivity analyses were comparable. There was no indication of heterogeneity or directional pleiotropy.ConclusionOur findings provide causal evidence for the effects of unpleasant emotions on coronary atherosclerosis

Genetic Evolution and Molecular Selection of the HE Gene of Influenza C Virus

Influenza C virus (ICV) was first identified in humans and swine, but recently also in cattle, indicating a wider host range and potential threat to both the livestock industry and public health than was originally anticipated. The ICV hemagglutinin-esterase (HE) glycoprotein has multiple functions in the viral replication cycle and is the major determinant of antigenicity. Here, we developed a comparative approach integrating genetics, molecular selection analysis, and structural biology to identify the codon usage and adaptive evolution of ICV. We show that ICV can be classified into six lineages, consistent with previous studies. The HE gene has a low codon usage bias, which may facilitate ICV replication by reducing competition during evolution. Natural selection, dinucleotide composition, and mutation pressure shape the codon usage patterns of the ICV HE gene, with natural selection being the most important factor. Codon adaptation index (CAI) and relative codon deoptimization index (RCDI) analysis revealed that the greatest adaption of ICV was to humans, followed by cattle and swine. Additionally, similarity index (SiD) analysis revealed that swine exerted a stronger evolutionary pressure on ICV than humans, which is considered the primary reservoir. Furthermore, a similar tendency was also observed in the M gene. Of note, we found HE residues 176, 194, and 198 to be under positive selection, which may be the result of escape from antibody responses. Our study provides useful information on the genetic evolution of ICV from a new perspective that can help devise prevention and control strategies

Edge-Mediated Skyrmion Chain and Its Collective Dynamics in a Confined Geometry

The emergence of a topologically nontrivial vortex-like magnetic structure, the magnetic skyrmion, has launched new concepts for memory devices. There, extensive studies have theoretically demonstrated the ability to encode information bits by using a chain of skyrmions in one-dimensional nanostripes. Here, we report the first experimental observation of the skyrmion chain in FeGe nanostripes by using high resolution Lorentz transmission electron microscopy. Under an applied field normal to the nanostripes plane, we observe that the helical ground states with distorted edge spins would evolves into individual skyrmions, which assemble in the form of chain at low field and move collectively into the center of nanostripes at elevated field. Such skyrmion chain survives even as the width of nanostripe is much larger than the single skyrmion size. These discovery demonstrates new way of skyrmion formation through the edge effect, and might, in the long term, shed light on the applications.Comment: 7 pages, 3 figure

Naphthalene-2,6-dicarb­oxy­lic acid–1-methyl­pyrrolidin-2-one (1/2)

The asymmetric unit of the title compound, C12H8O4·2C5H9NO, contains one half-mol­ecule of naphthalene-2,6-dicarb­oxy­lic acid (NDA) and one mol­ecule of 1-methyl­pyrrolidin-2-one (NMP): the NDA molecules lie on the crystallographic twofold rotation axes. In the crystal, the components are linked by strong O—H⋯O hydrogen bonds and C—H⋯O inter­actions

Petrogenesis of granitoids in the eastern section of the Central Qilian Block: Evidence from geochemistry and zircon U-Pb geochronology

The Caledonian-age Qilian Orogenic Belt at the northern margin of the Greater Tibetan Plateau comprises abundant granitoids that record the histories of the orogenesis. We report here our study of these granitoids from two localities. The Qingchengshan (QCS) pluton, which is situated in the eastern section of the Central Qilian Block, is dated at ~430–420 Ma. It has high-K calc-alkaline composition with high SiO2 (> 70 wt%), enrichment in large ion lithophile elements (LILEs), depletion in high field strength elements (HFSEs), and varying degrees of negative Sr and Eu anomalies. The granitoids in the Tongwei (TW) area, 150 km east of the QCS, are complex, the majority of which are dated at ~440 Ma, but there also exist younger, ~230 Ma intrusions genetically associated with the Qinling Orogeny. The Paleozoic TW intrusions also have high SiO2, fractionated REE (rare earth element) patterns, but a negligible Eu anomaly. The whole rock Sr-Nd-Hf isotopic compositions suggest that all these Paleozoic granitoids are consistent with melting-induced mixing of a two-component source, which is best interpreted as the combination of last fragments of subducted/subducting ocean crust with terrigenous sediments. The mantle isotopic signature of these granitoids (87Sr/86Sri: 0.7038 to 0.7100, εNd(t): −4.8 to −1.3, εHf(t): −0.7 to +4.0) reflects significant (~70 %) contribution of the ocean crust derived in no distant past from the mantle at ocean ridges with an inherited mantle isotopic signature. Partial melting of such ocean crust plus terrigenous sediments in response to the ocean closing and continental collision (between the Qilian and Alashan Blocks) under amphibolite facies conditions is responsible for the magmatism. Varying extents of fractional crystallization (±plagioclase, ±amphibole, ±garnet, ±zircon) of the parental magmas produced the observed QCS and TW granitoids. We note that sample HTC12–01 in the TW area shows an A-type or highly fractionated granite signature characterized by elevated abundances and a flat pattern of REEs, weak Nb-Ta anomaly, conspicuous negative Sr and Eu anomalies (Sr/Sr* = 0.09, Eu/Eu* = 0.22), and thus the high 87Sr/86Sr ratio (0.7851), and moderate εNd(t) (−4.9) and εHf(t) (−2.0), pointing to the significant mantle contribution. Compared with the Paleozoic granitoids, the ~230 Ma granitoids in the TW area represented by sample JPC12–02 have higher initial 87Sr/86Sr (0.7073) and lower εNd(t) (−6.2) and εHf(t) (−4.5) values, offering an ideal opportunity for future studies on tectonic effects of juxtaposition of younger orogenesis on an older orogen