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  1. Article ; Online: Compositely modulated structures of phosphor materials Sr

    Ooishi, Atsushi / Michiue, Yuichi / Funahashi, Shiro / Takeda, Takashi / Hirosaki, Naoto

    Acta crystallographica Section B, Structural science, crystal engineering and materials

    2020  Volume 76, Issue Pt 1, Page(s) 76–84

    Abstract: Composite crystals ... ...

    Abstract Composite crystals Sr
    Keywords covid19
    Language English
    Publishing date 2020-01-23
    Publishing country England
    Document type Journal Article
    ZDB-ID 2020841-8
    ISSN 2052-5206 ; 1600-5740 ; 1600-8650 ; 2052-5192
    ISSN (online) 2052-5206 ; 1600-5740 ; 1600-8650
    ISSN 2052-5192
    DOI 10.1107/S2052520619016391
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  2. Article: Mg(4)Sb(2)O(9) of the ilmenite structure type.

    Michiue, Yuichi

    Acta crystallographica. Section E, Structure reports online

    2008  Volume 64, Issue Pt 10, Page(s) i66

    Abstract: Single crystals of the title compound, tetra-magnesium dianti-monate(V), were obtained by the slow cooling method with K(2)CO(3). The structure is isotypic with ilmenite, which is constructed by the alternate stacking of layers consisting of metal-oxygen ...

    Abstract Single crystals of the title compound, tetra-magnesium dianti-monate(V), were obtained by the slow cooling method with K(2)CO(3). The structure is isotypic with ilmenite, which is constructed by the alternate stacking of layers consisting of metal-oxygen coordination octa-hedra. In each layer, the octa-hedra are connected by sharing edges so as to make holes. One of the two non-equivalent metal sites is fully occupied by Mg (3 symmetry), while the second metal site (3 symmetry) is disordered and occupied by Mg and Sb with occupation factors of 1/3 and 2/3, respectively.
    Language English
    Publishing date 2008-09-06
    Publishing country United States
    Document type Journal Article
    ZDB-ID 2041947-8
    ISSN 1600-5368
    ISSN 1600-5368
    DOI 10.1107/S160053680802789X
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  3. Article: Probability density analyses of guest ions in hollandite A(x)Mg(x/2)Ti(8 - x/2)O(16) (A = K, Rb).

    Michiue, Yuichi

    Acta crystallographica. Section B, Structural science

    2007  Volume 63, Issue Pt 4, Page(s) 577–583

    Abstract: Probability density functions (PDFs) of mobile ions in one-dimensional ionic conductors of hollandite A(x)Mg(x/2)Ti(8 - x/2)O(16) (A = K, Rb) were examined by single-crystal X-ray diffraction. A conventional structure model was modified by imposing an ... ...

    Abstract Probability density functions (PDFs) of mobile ions in one-dimensional ionic conductors of hollandite A(x)Mg(x/2)Ti(8 - x/2)O(16) (A = K, Rb) were examined by single-crystal X-ray diffraction. A conventional structure model was modified by imposing an additional constraint condition, which is based on microscopic description for the possible displacement of mobile ions adjacent to a vacancy in the tunnel. Joint PDFs and one-particle potentials for mobile ions were obtained from the structure models applying harmonic and anharmonic atomic displacement parameters (ADPs). Potential curves of the ion hopping between neighboring cavities were calculated from the joint PDF of the specific ions of the process. Energy barriers of the ion hopping were estimated at 52-60 meV from anharmonic ADP models of K-hollandite, while the values varied from 140 to 250 meV for Rb-hollandite.
    Language English
    Publishing date 2007-08
    Publishing country United States
    Document type Journal Article
    ZDB-ID 2020841-8
    ISSN 2052-5206 ; 1600-5740 ; 0108-7681 ; 2052-5192
    ISSN (online) 2052-5206 ; 1600-5740
    ISSN 0108-7681 ; 2052-5192
    DOI 10.1107/S0108768107023531
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  4. Article: Compositely modulated structures of phosphor materials SrxLi2+xAl2-xO4:Eu2

    Ooishi, Atsushi / Michiue, Yuichi / Funahashi, Shiro / Takeda, Takashi / Hirosaki, Naoto

    Acta Crystallogr B Struct Sci Cryst Eng Mater

    Abstract: Composite crystals SrxLi2+xAl2-xO4:Eu2+ were synthesized and their structures were determined using single-crystal X-ray diffraction. The commensurate structure with a modulation wavevector q = 5c*/6 was analyzed in a conventional manner in 3D space, ... ...

    Abstract Composite crystals SrxLi2+xAl2-xO4:Eu2+ were synthesized and their structures were determined using single-crystal X-ray diffraction. The commensurate structure with a modulation wavevector q = 5c*/6 was analyzed in a conventional manner in 3D space, while a structure model in (3+1)-dimensional superspace was used for the other two crystals with modulation wavevectors slightly differing from 5c*/6. The superstructure of the commensurate phase was described using the space group P4/n and a common superspace group I4/m(00γ)00 was used for the (3+1)D structures of all three crystals. The whole structure of each crystal consists of two substructures. Basis vectors a and b are common, but c is different for the two substructures. The first substructure is a host framework constructed by (Li/Al)O4 tetrahedra sharing edges. A linear connection of cavities is seen to be channel-like, in which Sr ions locate as guest cations forming the second substructure. The crystal of q = 5c*/6 contains five Sr ions per six cavities in a channel. Sr ions are distributed at seven sites, some of which are partially occupied. Statistical disorder of local structure models for the location of Sr ions in the channel was assumed to explain the results. Such a partially disordered character was also seen in the incommensurate phases and properly embodied by a (3+1)D model containing an atomic domain of the Sr ion with occupational modulation. Plots of the occupation factor, interatomic distances and the bond valence sum at each metal site as functions of t (= x4 - q·r) are roughly identical in the three crystals, which are considered as members of the same series of composite crystals.
    Keywords covid19
    Publisher WHO
    Document type Article
    Note WHO #Covidence: #32831243
    Database COVID19

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  5. Article: Incommensurately Modulated Crystal Structure and Photoluminescence Properties of Eu

    Nakano, Hiromi / Ando, Shota / Kamimoto, Konatsu / Hiramatsu, Yuya / Michiue, Yuichi / Hirosaki, Naoto / Fukuda, Koichiro

    Materials (Basel, Switzerland)

    2019  Volume 13, Issue 1

    Abstract: We prepared four types of ... ...

    Abstract We prepared four types of Eu
    Language English
    Publishing date 2019-12-20
    Publishing country Switzerland
    Document type Journal Article
    ZDB-ID 2487261-1
    ISSN 1996-1944
    ISSN 1996-1944
    DOI 10.3390/ma13010058
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  6. Article ; Online: Surface-Modified Two-Dimensional Titanium Carbide Sheets for Intrinsic Vibrational Signal-Retained Surface-Enhanced Raman Scattering with Ultrahigh Uniformity.

    Li, Guohui / Gong, Wen-Bin / Qiu, Tianlun / Cong, Shan / Zhao, Zhigang / Ma, Renzhi / Michiue, Yuichi / Sasaki, Takayoshi / Geng, Fengxia

    ACS applied materials & interfaces

    2020  Volume 12, Issue 20, Page(s) 23523–23531

    Abstract: Surface-enhanced Raman scattering (SERS) employing a non-noble substrate in comparison with conventional noble-metal ones offers advantages of low cost and rich selection of candidates; however, its application has been seriously hindered by its ... ...

    Abstract Surface-enhanced Raman scattering (SERS) employing a non-noble substrate in comparison with conventional noble-metal ones offers advantages of low cost and rich selection of candidates; however, its application has been seriously hindered by its unsatisfactory detection sensitivity, poor uniformity, and undesirable modification of vibrational signals via changing the orientation and/or polarizability of probe molecules. Here, an unusually sensitive but nonselective enhancement was achieved by employing titanium carbide sheets modified with aluminum oxyanions in situ as active supports for Raman measurement. The analyte molecules adopted a conformation similar to what they adopt on a bare substrate, while closely interacting with the aluminum oxyanion surface, which leads to the rare observation of highly sensitive but nonselective enhancement with a detection limit close to the pM level. With the substrate surface roughness in the nanometer region, an outstanding uniformity with a relative standard deviation of less than 4.3% was achieved. In addition, the SERS effect on the modified titanium carbide sheets was shown to be applicable to a wide range of analyte molecules, including both organic dyes and trace harmful compounds. The success of the work demonstrates the feasibility of surface tuning to improve the SERS effect, and it introduces a new window for two-dimensional materials in SERS applications.
    Language English
    Publishing date 2020-05-11
    Publishing country United States
    Document type Journal Article
    ISSN 1944-8252
    ISSN (online) 1944-8252
    DOI 10.1021/acsami.0c00908
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  7. Article ; Online: Superspace description of the homologous series Ga2O3(ZnO)m.

    Michiue, Yuichi / Kimizuka, Noboru

    Acta crystallographica. Section B, Structural science

    2010  Volume 66, Issue Pt 2, Page(s) 117–129

    Abstract: A unified description for the structures of the homologous series Ga(2)O(3)(ZnO)(m), gallium zinc oxide, is presented using the superspace formalism. The structures were treated as a compositely modulated structure consisting of two subsystems. One is ... ...

    Abstract A unified description for the structures of the homologous series Ga(2)O(3)(ZnO)(m), gallium zinc oxide, is presented using the superspace formalism. The structures were treated as a compositely modulated structure consisting of two subsystems. One is constructed with metal ions and the other with O ions. The ideal model is given, in which the displacive modulations of ions are well described by the zigzag function with large amplitudes. Alternative settings are also proposed which are analogous to the so-called modular structures. The validity of the model has been confirmed by refinements for phases with m = 6 and m = 9 in the homologous series. A few complex phenomena in real structures are taken into account by modifying the ideal model.
    Language English
    Publishing date 2010-04
    Publishing country United States
    Document type Journal Article
    ZDB-ID 2020841-8
    ISSN 1600-5740 ; 2052-5206 ; 2052-5192 ; 0108-7681
    ISSN (online) 1600-5740 ; 2052-5206
    ISSN 2052-5192 ; 0108-7681
    DOI 10.1107/S0108768109053713
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  8. Article: Exfoliated Ferrierite-Related Unilamellar Nanosheets in Solution and Their Use for Preparation of Mixed Zeolite Hierarchical Structures

    Roth, Wieslaw J. / Sasaki, Takayoshi / Wolski, Karol / Ebina, Yasuo / Tang, Dai-Ming / Michiue, Yuichi / Sakai, Nobuyuki / Ma, Renzhi / Cretu, Ovidiu / Kikkawa, Jun / Kimoto, Koji / Kalahurska, Katarzyna / Gil, Barbara / Mazur, Michal / Zapotoczny, Szczepan / Čejka, Jiri / Grzybek, Justyna / Kowalczyk, Andrzej

    Journal of the American Chemical Society. 2021 July 15, v. 143, no. 29

    2021  

    Abstract: Direct exfoliation of layered zeolites into solutions of monolayers has remained unresolved since the 1990s. Recently, zeolite MCM-56 with the MWW topology (layers denoted mww) has been exfoliated directly in high yield by soft-chemical treatment with ... ...

    Abstract Direct exfoliation of layered zeolites into solutions of monolayers has remained unresolved since the 1990s. Recently, zeolite MCM-56 with the MWW topology (layers denoted mww) has been exfoliated directly in high yield by soft-chemical treatment with tetrabutylammonium hydroxide (TBAOH). This has enabled preparation of zeolite-based hierarchical materials and intimate composites with other active species that are unimaginable via the conventional solid-state routes. The extension to other frameworks, which provides broader benefits, diversified activity, and functionality, is not routine and requires finding suitable synthesis formulations, viz. compositions and conditions, of the layered zeolites themselves. This article reports exfoliation and characterization of layers with ferrierite-related structure, denoted bifer, having rectangular lattice constants like those of the FER and CDO zeolites, and thickness of approximately 2 nm, which is twice that of the so-called fer layer. Several techniques were combined to prove the exfoliation, supported by simulations: AFM; in-plane, in situ, and powder X-ray diffraction; TEM; and SAED. The results confirmed (i) the structure and crystallinity of the layers without unequivocal differentiation between the FER and CDO topologies and (ii) uniform thickness in solution (monodispersity), ruling out significant multilayered particles and other impurities. The bifer layers are zeolitic with Brønsted acid sites, demonstrated catalytic activity in the alkylation of mesitylene with benzyl alcohol, and intralayer pores visible in TEM. The practical benefits are demonstrated by the preparation of unprecedented intimately mixed zeolite composites with the mww, with activity greater than the sum of the components despite high content of inert silica as pillars.
    Keywords X-ray diffraction ; alkylation ; benzyl alcohol ; catalytic activity ; crystal structure ; nanosheets ; silica ; tetrabutylammonium compounds ; topology ; zeolites
    Language English
    Dates of publication 2021-0715
    Size p. 11052-11062.
    Publishing place American Chemical Society
    Document type Article
    ZDB-ID 3155-0
    ISSN 1520-5126 ; 0002-7863
    ISSN (online) 1520-5126
    ISSN 0002-7863
    DOI 10.1021/jacs.1c04081
    Database NAL-Catalogue (AGRICOLA)

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  9. Article ; Online: Crystal Structure and Photoluminescence Properties of an Incommensurate Phase in EuO- and P

    Hiramatsu, Yuya / Michiue, Yuichi / Funahashi, Shiro / Hirosaki, Naoto / Banno, Hiroki / Urushihara, Daisuke / Asaka, Toru / Fukuda, Koichiro

    Inorganic chemistry

    2019  Volume 58, Issue 9, Page(s) 6155–6160

    Abstract: We have for the first time clarified the incommensurately modulated crystal structure as well as the photoluminescence properties of ... ...

    Abstract We have for the first time clarified the incommensurately modulated crystal structure as well as the photoluminescence properties of Eu
    Language English
    Publishing date 2019-04-23
    Publishing country United States
    Document type Journal Article
    ZDB-ID 1484438-2
    ISSN 1520-510X ; 0020-1669
    ISSN (online) 1520-510X
    ISSN 0020-1669
    DOI 10.1021/acs.inorgchem.9b00408
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  10. Article ; Online: Boron carbide, B(13-x)C(2-y) (x = 0.12, y = 0.01).

    Sologub, Oksana / Michiue, Yuichi / Mori, Takao

    Acta crystallographica. Section E, Structure reports online

    2012  Volume 68, Issue Pt 8, Page(s) i67

    Abstract: Boron carbide phases exist over a widely varying compos-itional range B(12+x)C(3-x) (0.06 < x < 1.7). One idealized structure corresponds to the B(13)C(2) composition (space group R-3m) and contains one icosa-hedral B(12) unit and one linear C-B-C chain. ...

    Abstract Boron carbide phases exist over a widely varying compos-itional range B(12+x)C(3-x) (0.06 < x < 1.7). One idealized structure corresponds to the B(13)C(2) composition (space group R-3m) and contains one icosa-hedral B(12) unit and one linear C-B-C chain. The B(12) units are composed of crystallographically distinct B atoms B(P) (polar, B1) and B(Eq) (equatorial, B2). Boron icosa-hedra are inter-connected by C atoms via their B(Eq) atoms, forming layers parallel to (001), while the B(12) units of the adjacent layers are linked through inter-icosa-hedral B(P)-B(P) bonds. The unique B atom (B(C)) connects the two C atoms of adjacent layers, forming a C-B-C chain along [001]. Depending on the carbon concentration, the carbon and B(P) sites exhibit mixed B/C occupancies to varying degrees; besides, the B(C) site shows partial occupancy. The decrease in carbon content was reported to be realized via an increasing number of chainless unit cells. On the basis of X-ray single-crystal refinement, we have concluded that the unit cell of the given boron-rich crystal contains following structural units: [B(12)] and [B(11)C] icosa-hedra (about 96 and 4%, respectively) and C-B-C chains (87%). Besides, there is a fraction of unit cells (13%) with the B atom located against the triangular face of a neighboring icosa-hedron formed by B(Eq) (B2) thus rendering the formula B(0.87)(B(0.98)C(0.02))(12)(B(0.13)C(0.87))(2) for the current boron carbide crystal.
    Language English
    Publishing date 2012-07-28
    Publishing country United States
    Document type Journal Article
    ZDB-ID 2041947-8
    ISSN 1600-5368 ; 1600-5368
    ISSN (online) 1600-5368
    ISSN 1600-5368
    DOI 10.1107/S1600536812033132
    Database MEDical Literature Analysis and Retrieval System OnLINE

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