Approximate perturbed direct homotopy reduction method: infinite series reductions to two perturbed mKdV equations

An approximate perturbed direct homotopy reduction method is proposed and applied to two perturbed modified Korteweg-de Vries (mKdV) equations with fourth order dispersion and second order dissipation. The similarity reduction equations are derived to arbitrary orders. The method is valid not only for single soliton solution but also for the Painlev\'e II waves and periodic waves expressed by Jacobi elliptic functions for both fourth order dispersion and second order dissipation. The method is valid also for strong perturbations.Comment: 8 pages, 1 figur

Experimental and analytical analysis of polarization and water transport behaviors of hydrogen alkaline membrane fuel cell

Experimental test and analytical modeling are conducted to investigate the operating behavior of an alkaline electrolyte membrane (AEM) fuel cell fed by H2/air (or O2) and explore the effect of various operating pressures on the water transfer mechanism. According to the experimental test, the cell performance is greatly improved through increasing the operating pressure gradient from anode to cathode which leads to significant liquid water permeation through the membrane. The high frequency resistance of the A901 alkaline membrane is observed to be relatively stable as the operating pressure varies based on the electrochemical impedance spectroscopy (EIS) method. Correspondingly, based on the modeling prediction, the averaged water content in the membrane electrode assembly (MEA) does not change too much which leads to the weak variation of membrane ohmic resistance. This reveals that the performance enhancement should give the credit to better electro-chemical reaction kinetics for both the anode and cathode, also prone by the EIS results. The reversion of water back diffusion direction across the membrane is also observed through analytical solution

Profiles of Impulsivity in Problematic Internet Users and Cigarette Smokers

Problematic Internet use (PIU) has been gradually recognized as a mental health issue among adolescents and young students. PIU shows many similarities with substance use disorders, but the shared and distinct mechanisms underlying them are unclear. The purpose of the current study was to explore the relationships between impulsive traits and PIU as well as cigarette smoking behaviors among young adults. Two independent samples of university students (N1 = 1281, N2 = 1034, respectively) over 3 years were assessed with multiple measurements of impulsivity, including the Barratt Impulsiveness Scale-11 (BIS-11), the UPPSP Impulsive Behaviors Scale (UPPSP), and the Delay-discounting Test (DDT). Logistic regression models revealed that across the two independent samples, BIS-11 Attentional Impulsiveness was the common trait positively predicting both PIU and cigarette smoking. While BIS-11 Motor Impulsiveness as well as UPPSP Lack of Perseverance, Lack of Premeditation, and Negative Urgency were the typical traits linked to PIU as positive predictors, UPPSP Sensation Seeking was the unique trait linked to cigarette smoking as a positive predictor. These results suggested that specific dimensions of impulsivity might be concurrently implicated in PIU and cigarette smoking among young adults, putatively representing important trait marks for addictive behaviors

1-Chloro­methyl-1H-1,2,3-benzotriazole

In the title compound, C7H6ClN3, the benzotriazole ring is essentially planar with a maximum deviation of 0.0110 (15)Å, and makes a dihedral angle of 0.46 (8)° with the benzene ring. In the crystal, mol­ecules are linked through inter­molecular C—H⋯N hydrogen bonds, forming chains along the c axis

Influence of grain size, shape and compaction on georadar waves: example of an Aeolian dune

Many Ground Penetrating Radar (GPR) profiles acquired in dry aeolian environment have shown good reflectivity inside present-day dunes. We show that the origin of this reflectivity is related to changes in grain size distribution, packing and/or grain shape in a sandy material. We integrate these three parameters into analytical models for bulk permittivity in order to predict the reflections and the velocity of GPR waves. We consider two GPR cross-sections acquired over Aeolian dunes in the Chadian desert. The 2D migration of GPR data suggests that dunes contain different kinds of bounding surfaces. We discuss and model three kinds of reflections using reasonable geological hypothesis about Aeolian sedimentation processes. The propagation and the reflection of radar waves are calculated using the 1D wavelet modelling method in spectral domain. The results of the forward modelling are in good accordance with real observed data

Determination of Polyphenol Content and Antioxidant Activity of Houttuynia cordata Leaves Using HPLC-ECD

Objective: To establish a high performance liquid chromatography-electrochemical detection (HPLC-ECD) method for the determination of polyphenolic compounds in the leaves of Houttuynia cordata and investigate the contribution of different compounds to the antioxidant activity by the correlation analysis. Methods: The leaves of Houttuynia cordata were extracted by ultrasonic extraction with 80% (v/v) methanol, and the content of 12 polyphenolic compounds was determined by the established HPLC-ECD method. The total phenolics content of Houttuynia cordata leaves was determined by the Folin-ciocalteu method. The antioxidant activities were evaluated by radical scavenging ability and ferric reducing antioxidant power (FRAP). Cluster heat map and gray correlation analysis were used for multivariate statistical analysis. Results: The established HPLC-ECD method showed good linearity, precision, repeatability and stability, with an average recovery of 93.25%~103.97% and RSD value of 1.99%~4.47%. The total phenolic content of Houttuynia cordata leaves from different sources ranged from 5.98~52.86 mg GAE/g, which was significantly correlated with ABTS+, DPPH radical scavenging ability and ferric ion reduction ability (P<0.05). The polyphenolic compounds with high content in Houttuynia cordata were derivatives of caffeic acid and quercetin. All of the 12 phenolic compounds had a high degree of correlation with antioxidant activity, among which isoquercitrin, quercetin, isochlorogenic acid A, hyperoside and rutin were the highest. The present study elucidated the primary antioxidant components in Houttuynia cordata leaves, which would provide reference for the quality evaluation and resource development of Houttuynia cordata

A preclinical animal study to evaluate the operability and safety of domestic one-way endobronchial valves

PurposeTo evaluate the operability and safety of bronchoscopic domestic one-way endobronchial valves (EBV) on animals.MethodsNine pigs were randomly assigned (2:1) to receive domestic one-way EBV (the experimental group, n = 6) and Zephyr® EBV (the control group, n = 3). Routine blood tests, arterial blood gases, and CT scans of the lungs were performed 1 day pre-procedure in addition to 1 week and 1 month post-procedure to assess changes in blood markers and lung volumes. At 1 month post-procedure, the animals were sacrificed, followed by removal of all valves via bronchoscopy. Pathological examinations of critical organs were subsequently performed.ResultsA total of 15 valves were placed in the experimental group and 6 valves were placed in the control group, without serious complications. Routine blood tests and arterial blood gas examinations at 1 day pre-procedure, 1 week post-procedure, and 1 month post-procedure did not differ significantly in both groups. No EBV displacement was noted under bronchoscopy, and the valve was smoothly removable by bronchoscope at 1 month post-procedure. At 1 week post-procedure, varying degrees of target lung lobe volume reduction were observed on lung CT in both groups. Lung volume reduction was achieved at 1 month post-procedure in both groups, without significant statistical difference. Although 3 cases in the experimental group and 1 case in the control group developed varying degrees of pneumonia, the inflammatory response did not increase over time during the experimental period. Pathological examination revealed no significant abnormal changes in the critical organs for both groups.ConclusionOur results demonstrate that domestic EBV is safe and reliable for endobronchial application in general-grade laboratory white pigs. The safety of domestic EBV is similar to that of Zephyr® EBV, with good ease of use and operability. This kind of domestic EBV can meet the safety evaluation requirements for animal testing

591 High-velocity Stars in the Galactic Halo Selected from LAMOST DR7 and Gaia DR2

In this paper, we report 591 high-velocity star candidates (HiVelSCs) selected from over 10 million spectra of Data Release 7 (DR7) of the Large Sky Area Multi-object Fiber Spectroscopic Telescope and the second Gaia data release, with three-dimensional velocities in the Galactic rest frame larger than 445 km s-1. We show that at least 43 HiVelSCs are unbound to the Galaxy with escape probabilities larger than 50%, and this number decreases to eight if the possible parallax zero-point error is corrected. Most of these HiVelSCs are metal-poor and slightly α-enhanced inner halo stars. Only 14% of them have [Fe/H] > -1, which may be the metal-rich "in situ"stars in the halo formed in the initial collapse of the Milky Way or metal-rich stars formed in the disk or bulge but kinematically heated. The low ratio of 14% implies that the bulk of the stellar halo was formed from the accretion and tidal disruption of satellite galaxies. In addition, HiVelSCs on retrograde orbits have slightly lower metallicities on average compared with those on prograde orbits; meanwhile, metal-poor HiVelSCs with [Fe/H] < -1 have an even faster mean retrograde velocity compared with metal-rich HiVelSCs. To investigate the origins of HiVelSCs, we perform orbit integrations and divide them into four types, i.e., hypervelocity stars, hyper-runaway stars, runaway stars and fast halo stars. A catalog for these 591 HiVelSCs, including radial velocities, atmospheric parameters, Gaia astrometric parameters, spatial positions, and velocities, etc., is available in the China-VO PaperData Repository at doi:10.12149/101038.Funding for the project has been provided by the National Development and Reform Commission. LAMOST is operated and managed by the National Astronomical Observatories, Chinese Academy of Sciences

Superconductivity and Charge-density-wave-like Transition in Th2Cu4As5

We report the synthesis, crystal structure, and physical properties of a novel ternary compound, Th$_2$Cu$_4$As$_5$. The material crystallizes in a tetragonal structure with lattice parameters $a=4.0716(1)$ {\AA} and $c=24.8131(4)$ {\AA}. Its structure can be described as an alternating stacking of fluorite-type Th$_2$As$_2$ layers with antifluorite-type double-layered Cu$_4$As$_3$ slabs. The measurement of electrical resistivity, magnetic susceptibility and specific heat reveals that Th$_2$Cu$_4$As$_5$ undergoes bulk superconducting transition at 4.2 K. Moreover, all these physical quantities exhibit anomalies at 48 K, where the Hall coefficient change the sign. These findings suggest a charge-density-wave-like (CDW) transition, making Th$_2$Cu$_4$As$_5$ a rare example for studying the interplay between CDW and superconductivity.Comment: 11 pages, 6 figures, and 1 tabl