2,234 research outputs found

    A new proof of some polynomial inequalities related to pseudo-splines

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    AbstractPseudo-splines of type I were introduced in [I. Daubechies, B. Han, A. Ron, Z. Shen, Framelets: MRA-based constructions of wavelet frames, Appl. Comput. Harmon. Anal. 14 (2003) 1–46] and [Selenick, Smooth wavelet tight frames with zero moments, Appl. Comput. Harmon. Anal. 10 (2000) 163–181] and type II were introduced in [B. Dong, Z. Shen, Pseudo-splines, wavelets and framelets, Appl. Comput. Harmon. Anal. 22 (2007) 78–104]. Both types of pseudo-splines provide a rich family of refinable functions with B-splines, interpolatory refinable functions and refinable functions with orthonormal shifts as special examples. In [B. Dong, Z. Shen, Pseudo-splines, wavelets and framelets, Appl. Comput. Harmon. Anal. 22 (2007) 78–104], Dong and Shen gave a regularity analysis of pseudo-splines of both types. The key to regularity analysis is Proposition 3.2 in [B. Dong, Z. Shen, Pseudo-splines, wavelets and framelets, Appl. Comput. Harmon. Anal. 22 (2007) 78–104], which also appeared in [A. Cohen, J.P. Conze, Régularité des bases d'ondelettes et mesures ergodiques, Rev. Mat. Iberoamericana 8 (1992) 351–365] and [I. Daubechies, Ten Lectures on Wavelets, CBMS-NSF Series in Applied Mathematics, SIAM, Philadelphia, 1992] for the case l=N−1. In this note, we will give a new insight into this proposition

    1-{2-[(2,4-Dichloro­benzyl­idene)amino]eth­yl}-3-methyl­imidazolium hexa­fluoro­phosphate

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    In the title Schiff base compound, C13H14Cl2N3 +·PF6 −, the dihedral angle between the aromatic ring and imidazole ring in the cation is 6.10 (2)°. Inter­molecular C—H⋯F hydrogen-bonding inter­actions and π–π stacking inter­actions [centoid–centroid distance = 3.7203 (12) Å] help stabilize the crystal packing

    Electrical Control of Magnetization in Charge-ordered Multiferroic LuFe2O4

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    LuFe2O4 exhibits multiferroicity due to charge order on a frustrated triangular lattice. We find that the magnetization of LuFe2O4 in the multiferroic state can be electrically controlled by applying voltage pulses. Depending on with or without magnetic fields, the magnetization can be electrically switched up or down. We have excluded thermal heating effect and attributed this electrical control of magnetization to an intrinsic magnetoelectric coupling in response to the electrical breakdown of charge ordering. Our findings open up a new route toward electrical control of magnetization.Comment: 14 pages, 5 figure

    3′,7′,7′-Trimethyl-1′-phenyl-5′,6′,7′,8′-tetra­hydro­spiro­[indoline-3,4′-(1H,4H-pyrazolo­[3,4-b]chromene)]-2,5′-dione

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    The title spiro­oxindole compound, C26H23N3O3, was prepared by the reaction of isatin, 3-methyl-1-phenyl-2-pyrazolin-5-one and 5,5-dimethyl­cyclo­hexane-1,3-dione in an ethanol solution. The fused cyclo­hexene ring adopts an envelope conformation. The dihedral angle between the aromatic and pyrazoline rings is 23.70 (8)°. An intra­molecular C—H⋯O inter­action occurs. The crystal structure is stabilized by N—H⋯N hydrogen-bonding inter­actions, leading to a zigzag chain along the b axis

    Bis(2,6-dichloro­benz­yl)selane

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    The title mol­ecule, C14H10Cl4Se, features a selenide bridge between two dichloro­benzyl units. The dihedral angle between the two benzene rings is 107.9 (16)°. In the crystal, weak π–π face-to-face aromatic inter­actions are observed [centroid–centroid distance between two adjacent (but crystallographically different) phenyl rings = 3.885 (5) Å], providing some packing stability. Short Cl⋯Cl contacts of 3.41 (2) Å are observed
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