Countable dense homogeneous filters and the Menger covering property

In this note we present a ZFC construction of a non-meager filter which fails to be countable dense homogeneous. This answers a question of Hern\'andez-Guti\'errez and Hru\v{s}\'ak. The method of the proof also allows us to obtain a metrizable Baire topological group which is strongly locally homogeneous but not countable dense homogeneous.Comment: 8 page

Reactions of Alcohols and Organophosphonates on Tungsten Trioxide Epitaxial Films

The adsorption, diffusion, reactions, and desorption of water, alcohols, ethers, and an organophosphonate were studied using calibrated thermal desorption spectroscopy (CTDS) on thin film WO3(OOl) surfaces grown epitaxially on a single crystal α- Al2O3(li02) (sapphire) substrate. The studies were conducted on oxidized and reduced surfaces, which were characterized by x-ray photoelectron spectroscopy (XPS) and ultraviolet photoelectron spectroscopy (UPS). The desorption spectra for molecular desorption of all of these molecules shifted to lower temperature with increasing coverage, and had overlapping tails on the high temperature side. Monte Carlo simulations show that this typical desorption shape can be characterized by first-order or pseudo-first-order desorption kinetics in which rapid diffusion allows the molecules to find and desorb from the most strongly bound sites of a heterogeneous surface. For methanol, UPS revealed molecular adsorption on the oxidized surface and dissociative adsorption on the reduced surface, but only molecular desorption of methanol was detected. For ethanol and isopropanol, competition between molecular desorption and dehydroxylation at lower temperature controls the alkoxy coverage remaining and consequently, the selectivity toward alkenes. The selectivity was coverage dependent, but was not significantly different on the oxidized and reduced WO3(001) surfaces. The rate limiting step in the dehydration of the alkoxy species to ethylene or propylene was identified as C-0 bond scission. Dimethoxymethane showed some decomposition to methanol on both surfaces, while only molecular desorption was found for dimethyl ether. Dimethyl methyl phosphonate (DMMP) decomposed on both the reduced and oxidized surfaces through loss of methoxy groups. Methanol and dimethyl ether were detected on the oxidized surface, while only dimethyl ether was observed on the reduced surface. Comparison of the dimethyl ether production with spectra following adsorption of dimethyl ether suggests that the rate limiting step is a surface catalyzed, intramolecular coupling reaction between methoxy groups. The C1s and P2p XPS features were consistent with a methyl phosphate-like species remaining after DMMP decomposition

An Image Segmentation Algorithm for Gradient Target Based on Mean-Shift and Dictionary Learning

In electromagnetic imaging, because of the diffraction limited system, the pixel values could change slowly near the edge of the image targets and they also change with the location in the same target. Using traditional digital image segmentation methods to segment electromagnetic gradient images could result in lots of errors because of this change in pixel values. To address this issue, this paper proposes a novel image segmentation and extraction algorithm based on Mean-Shift and dictionary learning. Firstly, the preliminary segmentation results from adaptive bandwidth Mean-Shift algorithm are expanded, merged and extracted. Then the overlap rate of the extracted image block is detected before determining a segmentation region with a single complete target. Last, the gradient edge of the extracted targets is recovered and reconstructed by using a dictionary-learning algorithm, while the final segmentation results are obtained which are very close to the gradient target in the original image. Both the experimental results and the simulated results show that the segmentation results are very accurate. The Dice coefficients are improved by 70% to 80% compared with the Mean-Shift only method

KIC 3440495: A Rapidly Rotating δ Scuti-γ Doradus Hybrid Pulsator in a Binary System

In this paper, we study the pulsation properties of KIC 3440495 using Kepler and TESS data. A Fourier analysis of the light curve reveals 24 pulsation modes as well as 29 frequencies associated with rotation. The rotation frequency is derived to be frot = 2.322909(2) day−1, and the rotational modulation is determined to be caused by starspots. A large frequency separation of Δν = 54.5 μHz is found by using a Fourier transform, the autocorrelation function, a histogram of frequency differences, and an échelle diagram. We use the large separation to estimate the refined stellar parameters of the star to be v = [239, 279] km s−1, M= [1.5, 1.65] Me, Requator = [2.03, 2.30] Re, Rpolar = [1.72, 1.78] Re, and ω = [0.61, 0.77]. The phase modulations of the pulsating frequencies show a long-term trend which may be attributed to an orbital effect of a binary system; hence, the star may be a fast rotating pulsator in a binary system. KIC 3440495 has an amplitude spectrum similar to Altair, and is identified as a potential sister of Altair. Based on studies of Altair, KIC 3330495 is presumably a young star at a similar evolutionary stage.National Natural Science Foundation of China (NSFC) 12003060 U2031209Natural Science Foundation of Xinjiang Uygur Autonomous Region 2020D01B59Chinese Academy of Sciences (CAS) "Light of West China" Program 2021-XBQNXZ-029"FEDER/Junta de Andalucia-Consejeria de Economia y Conocimiento" by Universidad de Granada E-FQM-041-UGR18"Programas Estatales de Generacion de Conocimiento y Fortalecimiento Cientifico y Tecnologico del Sistema de I+D+i y de I+D+i Orientada a los Retos de la Sociedad" from the Spanish Ministry of Science, Innovation and Universities (MCIU) PID2019-107061GB-C63State Agency for Research through the "Center of Excellence Severo Ochoa" award from the Spanish Ministry of Science, Innovation and Universities (MCIU) SEV-2017-070

The hypersurfaces with conformal normal Gauss map in H n+1 and S n+1

In this paper, we introduce the fourth fundamental forms for hypersurfaces in H n+1 and space-like hypersurfaces in S n+1 1 , and discuss the conformality of the normal Gauss map of the hypersurfaces in H n+1 and S n+1 1 . Particularly, we discuss the surfaces with conformal normal Gauss map in H 3 and S 3 1 , and prove a duality property. We give a Weierstrass representation formula for space-like surfaces in S 3 1 with conformal normal Gauss map. We also state the similar results for time-like surfaces in S 3 1 . Some examples of surfaces in S 3 1 with conformal normal Gauss map are given and a fully nonlinear equation of Monge-Ampère type for the graphs in S 3 1 with conformal normal Gauss map is derived

Enhanced Methanol Oxidation and CO Tolerance Using CeO\u3csub\u3e2\u3c/sub\u3e-Added Eggshell Membrane-Templated Pd Network Electrocatalyst

Macroporous Pd and CeO2-added Pd network catalysts have been synthesized using eggshell membrane (ESM) as a template for enhanced methanol oxidation and CO tolerance. The microstructural characterization revealed a hierarchically ordered macroporous network of Pd reproducing the fibrous structure of ESM for a Pd-only catalyst, and a flower-like CeO2-decorated Pd morphological architecture for the CeO2-added Pd catalyst synthesized by a precipitation method. XRD patterns indicated Pd and CeO2 phases with good crystallinity. The cyclic voltammetry studies showed an enhanced electrocatalytic activity for methanol oxidation in acidic aqueous medium. Because of the preferential formation of Ce–CO bonds over Pd–CO bonds, the incorporation of CeO2 into Pd-based catalysts results in an increased CO tolerance, making it a robust catalyst for methanol oxidation in direct methanol fuel cells