Change search
Refine search result
353637383940 1851 - 1900 of 1954
CiteExportLink to result list
Permanent link
Cite
Citation style
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf
Rows per page
  • 5
  • 10
  • 20
  • 50
  • 100
  • 250
Sort
  • Standard (Relevance)
  • Author A-Ö
  • Author Ö-A
  • Title A-Ö
  • Title Ö-A
  • Publication type A-Ö
  • Publication type Ö-A
  • Issued (Oldest first)
  • Issued (Newest first)
  • Created (Oldest first)
  • Created (Newest first)
  • Last updated (Oldest first)
  • Last updated (Newest first)
  • Disputation date (earliest first)
  • Disputation date (latest first)
  • Standard (Relevance)
  • Author A-Ö
  • Author Ö-A
  • Title A-Ö
  • Title Ö-A
  • Publication type A-Ö
  • Publication type Ö-A
  • Issued (Oldest first)
  • Issued (Newest first)
  • Created (Oldest first)
  • Created (Newest first)
  • Last updated (Oldest first)
  • Last updated (Newest first)
  • Disputation date (earliest first)
  • Disputation date (latest first)
Select
The maximal number of hits you can export is 250. When you want to export more records please use the Create feeds function.
  • 1851.
    Zhang, Daliang
    et al.
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Johnsson, Mats
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Kremer, R.K.
    Two New Layered Oxohalides in the System Cu-Yb-Te-O-Cl2010In: Solid State Sciences, ISSN 1293-2558, E-ISSN 1873-3085, Vol. 12, p. 536-540Article in journal (Refereed)
    Abstract [en]

    Two complex lanthanide(III) transition metal(II) tellurium(IV) oxyhalides, Cu3Yb2(TeO3)4Cl4 and Cu3Yb3(TeO3)4Cl6 have been synthesized and the crystal structures were determined by single-crystal X-ray diffraction. Both compounds are layered with only weak connections in between the layers. The layers are made up of [YbO8], [TeO3] and [CuOxCly] polyhedra. In both compounds the strong Lewis acid cations Yb3+ and Te4+ only form bonds to oxygen while Cu2+ form bonds to both oxygen and chlorine. This leads the Cl ions to be expelled from the bonding volumes of the crystal structures and protrude from the layers. Magnetic susceptibility measurements were performed on a powder sample of Cu3Yb2(TeO3)4Cl4. The Curie–Weiss law found at low temperatures indicates a Curie–Weiss temperature of ca. −5(1) K. However, indication for long-range magnetic ordering could not be observed down to 1.87 K. The two new phases are to the best of our knowledge the first containing all three of Cu, Yb and Te.

     

     

     

     

  • 1852.
    Zhang, Daliang
    et al.
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Oleynikov, Peter
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Hovmöller, Sven
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Zou, Xiaodong
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Collecting 3D electron diffraction data by the rotation method2010In: Zeitschrift fur Kristallographie, ISSN 0044-2968, Vol. 225, no 2-3, p. 94-102Article in journal (Refereed)
    Abstract [en]

    A new method for collecting complete three-dimensional electron diffraction data is described. Diffraction data is collected by combining electron beam tilt at many very small steps, with rotation of the crystal in a few but large steps. A number of practical considerations are discussed, as well as advantages and disadvantages compared to other methods of collecting electron diffraction data.

  • 1853.
    Zhang, Daliang
    et al.
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK), Inorganic and Structural Chemistry.
    Sun, Junliang
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK), Inorganic and Structural Chemistry.
    Han, Yu
    King Abdullah Univ Sci & Technol, Adv Membranes & Porous Mat Ctr, Thuwal 239556900, Saudi Arabia.
    Zou, Xiaodong
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK), Inorganic and Structural Chemistry.
    Structure study of the tri-continuous mesoporous silica IBN-9 by electron crystallography2011In: Microporous and Mesoporous Materials, ISSN 1387-1811, E-ISSN 1873-3093, Vol. 146, no 1-3, p. 88-96Article in journal (Refereed)
    Abstract [en]

    High resolution electron microscopy (HRTEM) has unique advantages for structural determination of nano-sized porous materials compared to X-ray diffraction, because it provides the important structure factor phase information which is lost in diffraction. Here we demonstrate the structure determination of the first tri-continuous mesoporous silica IBN-9 by electron crystallography. IBN-9 has a hexagonal unit cell with the space group P6(3)/mcm and a = 88.4 angstrom, c= 84.3 angstrom. HRTEM images taken along three main directions, [00 1], [1 (1) over bar 0] and [1 00] were combined to reconstruct the 3D electrostatic potential map, from which the tri-continuous pore structure of IBN-9 was discovered. The different steps of structure determination of unknown mesoporous structures by electron crystallography are described in details. Similar procedures can also be applied for structure determination of other porous and nonporous crystalline materials.

  • 1854.
    Zhang, Dong
    et al.
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK), Inorganic and Structural Chemistry.
    Johnsson, Mats
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK), Inorganic and Structural Chemistry.
    Lidin, Sven
    Kremer, Reinhard K.
    The new nickel tellurite chloride compound ni15te12o34cl10 synthesis, crystal structure and magnetic properties2013In: Dalton Transactions, ISSN 1477-9226, E-ISSN 1477-9234, Vol. 42, no 5, p. 1394-1399Article in journal (Refereed)
    Abstract [en]

    A new nickel tellurite oxohalide, Ni15Te12O34Cl10, has been prepared by chemical vapour transport reactions and the crystal structure was determined by single-crystal X-ray diffraction. The compound crystallizes in the triclinic space group P (1) over bar with the pseudomonoclinic cell parameters a = 10.3248(6) angstrom, b = 10.3249(6) angstrom, c = 11.6460(8) angstrom, alpha = 73.782(6)degrees, beta = 73.782(6)degrees, gamma = 63.51(2)degrees, Z = 1, R-1 = 0.0264. The Ni2+ ions have octahedral [NiO6] and [NiO4Cl2] coordinations, the Te4+ ions have one-sided [TeO3] and [TeO4] coordinations. The crystal structure can be described as consisting of nickel oxide ribbons extending along (001) that are connected by corner sharing [TeO3] and [TeO4] groups to build the open framework structure. The chlorine atoms and the Te-lone pairs are facing voids in the oxide framework. The new compound undergoes two successive antiferromagnetic ordering transitions at similar to 50 K and similar to 10 K. The Curie-Weiss temperature obtained from detailed evaluation of the high-temperature magnetic susceptibilities is positive indicating predominant ferromagnetic superexchange interactions between the Ni magnetic moments.

  • 1855.
    Zhang, Dong
    et al.
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK), Inorganic and Structural Chemistry.
    Kremer, Reinhard K.
    Lemmens, Peter
    Choi, Kwang-Yong
    Liu, Jia
    Whangbo, Myung-Hwan
    Berger, Helmuth
    Skourski, Yurii
    Johnsson, Mats
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK), Inorganic and Structural Chemistry.
    Crystal Structure and Magnetic Properties of Two New Antiferromagnetic Spin Dimer Compounds; FeTe3O7X (X = Cl, Br)2011In: Inorganic Chemistry, ISSN 0020-1669, E-ISSN 1520-510X, Vol. 50, no 24, p. 12877-12885Article in journal (Refereed)
    Abstract [en]

    Two new isostructural layered oxohalides FeTe(3)O(7)X (X = Cl, Br) were synthesized by chemical vapor transport reactions, and their crystal structures and magnetic properties were characterized by single-crystal X-ray diffraction, Raman spectroscopy, magnetic susceptibility and magnetization measurements, and also by density functional theory (DFT) calculations of the electronic structure and the spin exchange parameters. FeTe(3)O(7)X crystallizes in the monoclinic space group P2(1)/c with the unit cell parameters a = 10.7938(5), b = 7.3586(4), c = 10.8714(6) angstrom, beta = 111.041(5)degrees, Z = 4 for FeTe(3)O(7)CI, and a = 11.0339(10), b = 7.3643(10), c = 10.8892(10) angstrom, beta = 109.598(10)degrees, Z = 4 for FeTe(3)O(7)Br. Each compound has one unique Fe(3+) ion coordinating a distorted [FeO(5)] trigonal bipyramid. Two such groups share edges to form [Fe(2)O(8)] dimers that are isolated from each other by Te(4+) ions. The high-temperature magnetic properties of the compounds as well as spectroscopic investigations are consistent with an isolated antiferromagnetic spin dimer model with almost similar spin gaps of similar to 35 K for X = Cl and Br, respectively. However, deviations at low temperatures in the magnetic susceptibility and the magnetization data indicate that the dimers couple via an interdimer coupling. This interpretation is also supported by DFT calculations which indicate an interdimer exchange which amounts to 25% and 10% of the intradimer exchange for X = Cl and Br, respectively. The magnetic properties support the counterion character and a weak integration of halide ions into the covalent network similar to that in many other oxohalides.

  • 1856. Zhang, Fen
    et al.
    Liu, Yan
    Sun, Qi
    Dai, Zhifeng
    Gies, Hermann
    Wu, Qinming
    Pan, Shuxiang
    Bian, Chaoqun
    Tian, Zhijian
    Meng, Xiangju
    Zhang, Yi
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Zou, Xiaodong
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Yi, Xianfeng
    Zheng, Anmin
    Wang, Liang
    Xiao, Feng-Shou
    Design and preparation of efficient hydroisomerization catalysts by the formation of stable SAPO-11 molecular sieve nanosheets with 10-20 nm thickness and partially blocked acidic sites2017In: Chemical Communications, ISSN 1359-7345, E-ISSN 1364-548X, Vol. 53, no 36, p. 4942-4945Article in journal (Refereed)
    Abstract [en]

    SAPO-11 nanosheets with partially filled micropores (N-SAPO-11) and a thickness of 10-20 nm were synthesized using polyhexamethylene biguanide hydrochloride (PHMB) as a mesoporogen and di-npropylamine (DPA) as a microporous template. After Pt loading (0.5 wt%), the Pt/N-SAPO-11 catalyst exhibits higher selectivity for the isomers and lower selectivity for cracking products than conventional Pt/SAPO-11 catalysts in the hydroisomerization of n-dodecane.

  • 1857. Zhang, H.
    et al.
    Zou, Xiaodong
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK), Inorganic and Structural Chemistry.
    Oleynikov, Peter
    Stockholm University, Faculty of Science, Department of Physical, Inorganic and Structural Chemistry.
    Hovmöller, Sven Erik
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK), Inorganic and Structural Chemistry.
    Structure relations in real and reciprocal space of hexagonal phases related to i-ZnMgRE quasicrystals2006In: Philosophical Magazine, ISSN 1478-6435, E-ISSN 1478-6443, Vol. 86, no 3-5, p. 343-348Article in journal (Refereed)
    Abstract [en]

    The µ 3 , µ 5 and µ 7 approximants in Mg-Zn-RE were related in real and reciprocal space. The structure factors of µ 3 , µ 5 and µ 7 have quite similar intensity distributions and identical phases for the strongest corresponding reflections. Structure models of any of µ 3 , µ 5 and µ 7 can be obtained from any of the others using the strong reflections approach.

  • 1858. Zhang, Kaiheng
    et al.
    Deiana, Luca
    Svensson Grape, Erik
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Inge, A. Ken
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Córdova, Armando
    Catalytic Enantioselective Synthesis of Bicyclic Lactam N,S-Acetals in One Pot by Cascade Transformations2019In: European Journal of Organic Chemistry, ISSN 1434-193X, E-ISSN 1099-0690, no 29, p. 4649-4657Article in journal (Refereed)
    Abstract [en]

    A versatile strategy for the enantioselective synthesis of bicyclic lactam N,S-acetals by one-pot cascade transformations is disclosed. The transformation of readily available substrates is promoted by chiral amines and creates bicyclic or tricyclic lactam N,S-acetals with high chemo- and stereoselectivity (up to > 99.5:0.5 dr and > 99 % ee) in one-pot operations.

  • 1859. Zhang, Kaiyou
    et al.
    Chen, Hong
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Wang, Xue
    Guo, Donglin
    Hu, Chenguo
    Wang, Shuxia
    Sun, Junliang
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Leng, Qiang
    Synthesis and structure determination of potassium copper selenide nanowires and solid-state supercapacitor application2014In: Journal of Power Sources, ISSN 0378-7753, E-ISSN 1873-2755, Vol. 268, p. 522-532Article in journal (Refereed)
    Abstract [en]

    The new ternary alkali metal copper chalcogenide KCu4Se8 nanowires with average length of 30 mu m are synthesized using a modified composite-hydroxide mediated (M-CHM) approach. The prepared KCu4Se8 is characterized by XRD, EDS, FESEM and TEM analysis. The structure is determined by the newly developed Rotation Electron Diffraction technique. It is identified to be a body center tetragonal phase. The prepared KCu4Se8 is used to fabricate solid-state supercapacitors in which the thin film of the electrodes are made with pressure of 0 MPa, 5 MPa and 10 MPa, and their electrochemical properties are tested. It is found that 0 MPa supercapacitor displays best electrochemical performance and the specific capacitance of 25.3 F g(-1) is obtained at the scan rate of 5 mV s(-1). It also shows good long-term cycle property by recording 5000 cycles of galvanostatic charge/discharge operation. The specific capacitance can be enhanced to 93.7 F g(-1) at the scan rate of 5 mV s(-1) by coating 0.1 mg V2O5 nanowire on 0 MPa KCu4Se8 electrode.

  • 1860. Zhang, Peili
    et al.
    Wang, Mei
    Chen, Hong
    Liang, Yongqi
    Sun, Junliang
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Sun, Licheng
    A Cu-Based Nanoparticulate Film as Super-Active and Robust Catalyst Surpasses Pt for Electrochemical H-2 Production from Neutral and Weak Acidic Aqueous Solutions2016In: Advanced Energy Materials, ISSN 1614-6832, Vol. 6, no 8, article id 1502319Article in journal (Refereed)
    Abstract [en]

    Electrocatalysts that are stable and highly active at low overpotential (eta) under mild conditions as well as cost-effective and scalable are eagerly desired for potential use in photo-and electro-driven hydrogen evolution devices. Here the fabrication and characterization of a super-active and robust Cu-CuxO-Pt nanoparticulate electrocatalyst is reported, which displays a small Tafel slope (44 mV dec(-1)) and a large exchange current density (1.601 mA cm(-2)) in neutral buffer solution. The catalytic current density of this catalyst film reaches 500 mA cm(-2) at eta = -390 +/- 12 mV and 20 mA cm(-2) at eta = -45 +/- 3 mV, which are significantly higher than the values displayed by Pt foil and Pt/C electrodes in neutral buffer solution and even comparable with the activity of Pt electrode in 0.5 M H2SO4 solution.

  • 1861. Zhang, Qiang
    et al.
    Su, Jie
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Feng, Dawei
    Wei, Zhangwen
    Zou, Xiaodong
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Zhou, Hong-Cai
    Piezofluorochromic Metal-Organic Framework: A Microscissor Lift2015In: Journal of the American Chemical Society, ISSN 0002-7863, E-ISSN 1520-5126, Vol. 137, no 32, p. 10064-10067Article in journal (Refereed)
    Abstract [en]

    We have successfully constructed a metal-organic framework, denoted as PCN-128W, starting from chromophoric linker and zirconium salt. PCN-128W exhibits interesting piezofluorochromic behavior, the color reversibly changes from white to yellow and so does the emission maximum from 470 to 538 nm. The stepwise fluorescence change was monitored by fluorospectroscopy which demonstrated gradual shift of the emission maximum when sequential compression was exerted. In order to gain deep insights into the piezofluorochromic mechanism, both the white and yellow phases are structurally characterized.

  • 1862. Zhang, Ranran
    et al.
    Elkhooly, Tarek A.
    Huang, Qianli
    Liu, Xujie
    Yang, Xing
    Yan, Hao
    Xiong, Zhiyuan
    Ma, Jing
    Feng, Qingling
    Shen, Zhijian
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK). Tsinghua University, China.
    A dual-layer macro/mesoporous structured TiO2 surface improves the initial adhesion of osteoblast-like cells2017In: Materials science & engineering. C, biomimetic materials, sensors and systems, ISSN 0928-4931, E-ISSN 1873-0191, Vol. 78, p. 443-451Article in journal (Refereed)
    Abstract [en]

    A dual-layer TiO2 surface with hierarchical macro and mesoporous structure was prepared by a combinational approach of micro-arc oxidation followed by evaporation-induced self-assembly of nano-crystallites. The mesoporous layer contains pores with an average size of <10 nm and consists of anatase TiO2 nanocrystallites. The dual-layer hierarchical macro/mesoporous structured TiO2 surface improves the hydrophilicity and fibronectin adsorption ability in comparison with the sole macroporous or smooth TiO2 surface. With the formation of an additional mesoporous layer on macroporous TiO2 surface, the attached number of human osteogenic sarcoma cells (SaOS-2) increases in the initial incubation of 4 h but it does not show significant difference after 24 h compared to that attached on the macroporous or smooth surfaces. Whereas, it was noticed that SaOS-2 cells have larger spread area and more stress fibers on the macro/mesoporous structured surface than those on the other surfaces. To understand the intracellular mechanism of the initial cell adhesion on the macro/mesoporous surface, the Rho/ROCK pathway was investigated to reveal the topography-induced biological functions by introducing the ROCK inhibitor Y-27632 during cell culture. In the presence of Y-27632, cells on the macroporous surface and macro/mesoporous surface both show stellate appearance, with poor assembly stress fibers and long cell membrane protrusions. Cells on the smooth surface have larger spread areas compared to the former two surfaces. And the attached cells significantly reduced but there are no differences among the three surfaces. It reveals that the ROCK inhibitor invalidates the promotion of initial cell adhesion on the macro/mesoporous structure. This study may shed light on the mechanism behind the enhancement effect of macro/mesoporous structure for initial cell adhesion.

  • 1863. Zhang, Ranran
    et al.
    Elkhooly, Tarek A.
    Huang, Qianli
    Liu, Xujie
    Yang, Xing
    Yan, Hao
    Xiong, Zhiyuan
    Ma, Jing
    Feng, Qingling
    Shen, Zhijian
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK). Tsinghua University, China.
    Effects of the hierarchical macro/mesoporous structure on the osteoblast-like cell response2018In: Journal of Biomedical Materials Research. Part A, ISSN 1549-3296, E-ISSN 1552-4965, Vol. 106, no 7, p. 1896-1902Article in journal (Refereed)
    Abstract [en]

    To improve the success of medical devices, implants with strong surface bioactivity are urgently required. Coatings with a macroporous structure produced by micro-arc oxidation possess advantages, such as strong adhesion to substrate and excellent resistance to wear and corrosion. Mesoporous structures contain pores with sizes of 2-50 nm, which can endow the biomaterials with the ability to enhance osteogenesis and to be loaded with diverse drugs. Thus, in this study, we aimed to evaluate the effects of both macroporous and mesoporous structures using a hierarchical macro/mesoporous structure to modify the titanium implant surface. The behaviors of SaOS-2 human osteosarcoma cells on the macro/mesoporous structure, including initial adhesion, proliferation, alkaline phosphatase (ALP) activity, and collagen secretion, were investigated. Cells that attached on the macro/mesoporous surface showed the highest cell numbers and greatest spreading area after incubation for 1, 2, and 4 h compared with the polished smooth substrate and macroporous surface in the presence of fetal bovine serum (FBS). However, in the absence of FBS, cell adhesion on the polished substrate, macroporous structure, and macro/mesoporous structure did not differ significantly. Cell proliferation on the macroporous and macro/mesoporous surfaces increased compared with that on the smooth substrate surface. Furthermore, ALP activity and collagen secretion were enhanced on the macro/mesoporous structure. Our findings provided important insights into the cellular responses to macro/mesoporous structures in the field of implant surface modification.

  • 1864. Zhang, Ranran
    et al.
    Huang, Qianli
    Liu, Xujie
    Yang, Xing
    Yan, Hao
    Xiong, Zhiyuan
    Xu, Nan
    Ma, Jing
    Feng, Qingling
    Shen, Zhijian
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK). Tsinghua University, China.
    ZnO nanostructures enhance the osteogenic capacity of SaOS-2 cells on acid-etched pure Ti2018In: Materials letters (General ed.), ISSN 0167-577X, E-ISSN 1873-4979, Vol. 215, p. 173-175Article in journal (Refereed)
    Abstract [en]

    Zinc oxide (ZnO) has attracted a great deal of interest due to its electronic and optical properties, and has potential applications in biomedical field, while few studies have been conducted to investigate its biocompatibility. In this study, we prepared nanostructured ZnO on acid-etched pure Ti surface through a moderate hydrothermal treatment in ammonia solution (pH = 12.6). By changing Zn precursor concentration and hydrothermal duration, it was feasible to synthesis flake-like ZnO nanostructures with variable spacings. The adhesion, proliferation and alkaline phosphatase (ALP) activity of SaOS-2 cells were enhanced on the ZnO nanostructures when the Zn precursor concentration was 0.02 M and the hydrothermal duration was 4 h, compared to those on the acid-etched pure Ti without ZnO nanostructures. Narrower spacings (< 70 nm) between ZnO nanostructures are considered to contribute to this enhancement. Together, the results indicate that the superposition of ZnO nanostructures on titanium surfaces may be beneficial for the enhanced biological performance.

  • 1865. Zhang, Ranran
    et al.
    Liu, Xujie
    Xiong, Zhiyuan
    Huang, Qianli
    Yang, Xing
    Yan, Hao
    Ma, Jing
    Feng, Qingling
    Shen, Zhijian
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK). Tsinghua University, China.
    Novel micro/nanostructured TiO2/ZnO coating with antibacterial capacity and cytocompatibility2018In: Ceramics International, ISSN 0272-8842, E-ISSN 1873-3956, Vol. 44, no 8, p. 9711-9719Article in journal (Refereed)
    Abstract [en]

    Insufficient osseointegration between implants and bone, and peri-implant infection are the two most common factors contributing to implantation failure. As such, implant materials should ideally be designed with antibacterial capacity while maintaining cytocompatibility. Combining Zn, a known antibacterial agent, with micro/nanostructures on the implant surface to promote osseointegration, potentially reduces peri-implant infection. To this end, in the present study, we developed novel bifunctional micro/nanostructured titanium oxide/zinc oxide (TiO2/ZnO) coating by micro-arc oxidation (MAO) followed by hydrothermal treatment. The release rate of the Zn2+ ions was reduced by heat treatment which established a balance between antibacterial capacity and cytocompatibility. The results demonstrate a simple approach for developing a Zn-based material that balances antibacterial capacity and cytocompatibility as a promising coating material for Ti implants.

  • 1866. Zhang, Ranran
    et al.
    Liu, Xujie
    Xiong, Zhiyuan
    Huang, Qianli
    Yang, Xing
    Yan, Hao
    Ma, Jing
    Feng, Qingling
    Shen, Zhijian
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK). Tsinghua University, Beijing, China.
    The immunomodulatory effects of Zn-incorporated micro/nanostructured coating in inducing osteogenesis2018In: Artificial cells nanomedicine and biotechnology, ISSN 2169-1401, Vol. 46, p. S1123-S1130Article in journal (Refereed)
    Abstract [en]

    Micro/nanostructured TiO2/ZnO coating has been shown to possess multiple functions, including antibacterial activity and bioactivity. Osteoblast-like SaOS-2 cells were employed for evaluating the in vitro osteogenic capacity of this coating and positive results were obtained. However, traditional principles of osseointegration focus only on the osteogenic differentiation alone. The effects of immunomodulation on the osteogenic activity have been largely ignored. In this study, the inflammatory responses of macrophages on the micro/nanostructured TiO2/ZnO coating were investigated. The extract media of macrophage cell line RAW264.7 cultured on the TiO2/ZnO coating were collected as indirect co-culture conditioned media. The osteogenic activity of SaOS-2 cells in the conditioned media was investigated. Adhesion, ALP activity and extracellular mineralization of cells grown in the conditioned media extracted from the micro/nanostructured TiO2/ZnO coating were found to be enhanced, compared to those grown in the conditioned media extracted from the macroporous TiO2 coating. The immune microenvironment produced by the micro/nanostructured TiO2/ZnO coating showed excellent capacity to promote osteogenesis, indicating that this coating could be a promising candidate for implant surface modification in orthopaedic and dental applications. Furthermore, this work could help us understand the interplay between the host immune system and the osteoimmunomodulatory properties of the biomaterials, and optimize the design for coating biomaterials.

  • 1867. Zhang, Ranran
    et al.
    Xu, Nan
    Liu, Xujie
    Yan, Hao
    Ma, Jing
    Feng, Qingling
    Shen, Zhijian
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK). Tsinghua University, People’s Republic of China.
    Dose-dependent enhancement of bioactivity by surface ZnO nanostructures on acid-etched pure titanium2019In: Advances in Applied Ceramics: Structural, Functional and Bioceramics, ISSN 1743-6753, E-ISSN 1743-6761, Vol. 118, no 3, p. 121-125Article in journal (Refereed)
    Abstract [en]

    Zinc (Zn) is found to be essential in biologic osseous functions, and deficiency of Zn may cause delayed skeletal growth and osteoporosis. Additionally, Zn-based coatings are reported to be effective to promote the bioactivity of implants. In this study, we employed the hydrothermal treatment to incorporate Zn into the surface of acid-etched pure Ti. The process was conducted in ammonia solution with an increased Zn precursor concentration (0.0002M, 0.002M and 0.02M, respectively). XPS analysis demonstrated that the nanostructures were composed of ZnO. Proliferation and alkaline phosphatase (ALP) activity of osteoblast-like SaOS-2 cells were enhanced dose-dependently, compared to those on the acid-etched pure Ti without ZnO nanostructures. This study addresses a favourable surface modification method to improve the bioactivity of implants.

  • 1868. Zhang, Ranran
    et al.
    Xu, Nan
    Liu, Xujie
    Yang, Xing
    Yan, Hao
    Ma, Jing
    Feng, Qingling
    Shen, Zhijian
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK). Tsinghua University, China.
    Micro/nanostructured TiO2/ZnO coating enhances osteogenic activity of SaOS-2 cells2019In: Artificial cells nanomedicine and biotechnology, ISSN 2169-1401, Vol. 47, no 1, p. 2838-2845Article in journal (Refereed)
    Abstract [en]

    Although titanium implants account for a large proportion of the commercial dental market, their bioactivity are inadequate in many applications. A micro- and nano- scale hierarchical surface topography of the implant is suggested for rapid osseointegration from the biomimetic perspective. Moreover, Zinc (Zn) is an essential element in the skeletal system. Thus, a micro/nanostructured TiO2/ZnO coating, produced by micro-arc oxidation, and hydrothermal treatment, and heat treatment, was designed to endow the implant surface with enhanced osteogenic capacity. Physiochemical properties and biological effects of this coating were investigated in our study. The annealed micro/nanostructured TiO2/ZnO coating exhibited higher hydrophilicity and fibronectin adsorption ability compared to the micro-arc oxidation modified TiO2 coating. SaOS-2 cells grown on the annealed micro/nanostructured TiO2/ZnO coating showed increased alkaline phosphatase activity and collagen secretion, and immunofluorescence labeling revealed an upregulation of osteopontin, collagen type iota and osteocalcin. The micro/nanostructure and incorporation of Zn were considered to perform positive effect on the enhanced osteogenic activity of SaOS-2 cells. In conclusion, the micro/nanostructured TiO2/ZnO structure is simple, stable, and easy to produce and scale up, has promising applications in the surface modification of titanium implants.

  • 1869. Zhang, Shuo
    et al.
    Chen, Hong
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK). China University of Geosciences, People's Republic of China.
    Rasmuson, Åke C.
    Thermodynamics and crystallization of a theophylline-salicylic acid cocrystal2015In: CrystEngComm, ISSN 1466-8033, E-ISSN 1466-8033, Vol. 17, no 22, p. 4125-4135Article in journal (Refereed)
    Abstract [en]

    A 1: 1 theophylline-salicylic acid cocrystal has been successfully prepared by slurry conversion crystallization in a 1 : 1 molar ratio slurry of theophylline and salicylic acid in chloroform. The cocrystal powder was analysed by XRD and DSC, and the cocrystal structure was determined by single crystal XRD. The cocrystal melts at 188.5 degrees C, which is between the melting points of the pure cocrystal components. Microscopy and SEM images have been taken for the cocrystals prepared by slow evaporation from ethanol, ethyl acetate, or acetonitrile. The cocrystal dissolves congruently in chloroform and the solubility is determined. Based on the solubility data for the cocrystal and the pure components, the Gibbs free energy of cocrystal formation is calculated to be -4.92 kJ mol(-1) at 30 degrees C. The cocrystal dissolves incongruently in methanol, ethanol, and acetonitrile. The ternary phase diagram of the cocrystal in acetonitrile has been determined and compared with those of theophylline-oxalic acid and theophylline-glutaric acid cocrystal systems. By proper operation of the process in the phase diagram, the theophylline-salicylic acid cocrystal can be produced by slurry conversion crystallization in acetonitrile.

  • 1870. Zhang, Su-Yun
    et al.
    Kochovski, Zdravko
    Lee, Hui-Chun
    Lu, Yan
    Zhang, Hemin
    Zhang, Jie
    Sun, Jian-Ke
    Yuan, Jiayin
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Ionic organic cage-encapsulating phase-transferable metal clusters2019In: Chemical Science, ISSN 2041-6520, E-ISSN 2041-6539, Vol. 10, no 5, p. 1450-1456Article in journal (Refereed)
    Abstract [en]

    Exploration of metal clusters (MCs) adaptive to both aqueous and oil phases without disturbing their size is promising for a broad scope of applications. The state-of-the-art approach via ligandbinding may perturb MCs' size due to varied metal-ligand binding strength when shuttling between solvents of different polarity. Herein, we applied physical confinement of a series of small noble MCs (<1 nm) inside ionic organic cages (I-Cages), which by means of anion exchange enables reversible transfer of MCs between aqueous and hydrophobic solutions without varying their ultrasmall size. Moreover, the MCs@I-Cage hybrid serves as a recyclable, reaction-switchable catalyst featuring high activity in liquid-phase NH3BH3 (AB) hydrolysis reaction with a turnover frequency (TOF) of 115 min(-1).

  • 1871. Zhang, Weiyi
    et al.
    Zhao, Qiang
    Yuan, Jiayin
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK). Clarkson University, USA.
    Porous Polyelectrolytes: The Interplay of Charge and Pores for New Functionalities2018In: Angewandte Chemie International Edition, ISSN 1433-7851, E-ISSN 1521-3773, Vol. 57, no 23, p. 6754-6773Article, review/survey (Refereed)
    Abstract [en]

    The past decade has witnessed rapid advances in porous polyelectrolytes and there is tremendous interest in their synthesis as well as their applications in environmental, energy, biomedicine, and catalysis technologies. Research on porous polyelectrolytes is motivated by the flexible choice of functional organic groups and processing technologies as well as the synergy of the charge and pores spanning length scales from individual polyelectrolyte backbones to their nano-/micro-superstructures. This Review surveys recent progress in porous polyelectrolytes including membranes, particles, scaffolds, and high surface area powders/resins as well as their derivatives. The focus is the interplay between surface chemistry, Columbic interaction, and pore confinement that defines new chemistry and physics in such materials for applications in energy conversion, molecular separation, water purification, sensing/actuation, catalysis, tissue engineering, and nanomedicine.

  • 1872. Zhang, Xin
    et al.
    Yu, Xiangwen
    Zhou, Beiying
    Luo, Wei
    Jiang, Wan
    Jiang, Weihui
    Shen, Zhijian
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Wang, Lianjun
    Sinterability Enhancement by Collapse of Mesoporous Structure of SBA-15 in Fabrication of Highly Transparent Silica Glass2015In: Journal of The American Ceramic Society, ISSN 0002-7820, E-ISSN 1551-2916, Vol. 98, no 4, p. 1056-1059Article in journal (Refereed)
    Abstract [en]

    Highly transparent silica glass was prepared from mesoporous silica SBA-15 powders at low temperature using Spark Plasma Sintering. It was found that the combined effect of pressure and temperature resulted in collapse of porous structure of SBA-15 and transformation to transparent glass. A sinterability enhancement mechanism involving generation of incremental surface area from pore collapse during sintering process was proposed to interpret the fully densification at low temperature.

  • 1873.
    Zhang, Xueyi
    et al.
    Department of Chemical Engineering and Materials Science, University of Minnesota, Minneapolis, MN 55455, USA. .
    Liu, Dongxia
    Department of Chemical Engineering and Materials Science, University of Minnesota, Minneapolis, MN 55455, USA. .
    Xu, Dandan
    Department of Chemical Engineering and Materials Science, University of Minnesota, Minneapolis, MN 55455, USA. .
    Asahina, Shunsuke
    SM Application Group, JEOL Ltd., Akisima, Tokyo 196-8558, Japan.
    Cychosz, Katie A.
    Quantachrome Instruments, 1900 Corporate Drive, Boynton Beach, FL 33426, USA.
    Agrawal, Kumar Varoon
    Department of Chemical Engineering and Materials Science, University of Minnesota, Minneapolis, MN 55455, USA.
    Al Wahedi, Yasser
    Department of Chemical Engineering and Materials Science, University of Minnesota, Minneapolis, MN 55455, USA.
    Bhan, Aditya
    Department of Chemical Engineering and Materials Science, University of Minnesota, Minneapolis, MN 55455, USA.
    Al Hashimi, Saleh
    Chemical Engineering Program, Petroleum Institute, Abu Dhabi, United Arab Emirates.
    Terasaki, Osamu
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Thommes, Matthias
    Quantachrome Instruments, 1900 Corporate Drive, Boynton Beach, FL 33426, USA.
    Tsapatsis, Michael
    Department of Chemical Engineering and Materials Science, University of Minnesota, Minneapolis, MN 55455, USA.
    Synthesis of Self-Pillared Zeolite Nanosheets by Repetitive Branching2012In: IBS Journal of Science, ISSN 1751-0724, E-ISSN 1751-0724, Vol. 336, no 6089, p. 1684-1687Article in journal (Refereed)
    Abstract [en]

    Hierarchical zeolites are a class of microporous catalysts and adsorbents that also contain mesopores, which allow for fas transport of bulky molecules and thereby enable improved performance in petrochemical and biomass processing. We used repetitive branching during one-step hydrothermal crystal growth to synthesize a new hierarchical zeolite made of orthogonally connected microporous nanosheets. The nanosheets are 2 nanometers thick and contain a network of 0.5-nanometer micropores. The house-of-cards arrangement of the nanosheets creates a permanent network of 2- to 7-nanometer mesopores, which, along with the high external surface area and reduced micropore diffusion length, account for higher reaction rates for bulky molecules relative to those of other mesoporous and conventional MFI zeolites.

  • 1874. Zhang, Youdong
    et al.
    Han, Jian-min
    Zheng, Gang
    Lin, Hong
    Bai, Wei
    Zhao, Jing
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Shen, Zhijian
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Fatigue behaviours of the zirconia dental restorations prepared by two manufacturing methods2017In: Advances in Applied Ceramics: Structural, Functional and Bioceramics, ISSN 1743-6753, E-ISSN 1743-6761, Vol. 116, no 7, p. 368-375Article in journal (Refereed)
    Abstract [en]

    The fatigue behaviours were evaluated on a novel zirconia dental restoration known as self-glazed zirconia (SG), prepared by a precision additive 3D gel deposition approach, compared with a conventional zirconia (CZ) restoration, shaped by CNC milling of zirconia blanks made by cold isostatic pressing. Eight fixed partial dentures made by each method were subjected to fracture test, without or with the application of 5-million fatigue cycles, respectively. The processing defects, grain size, and t-m phase transformation were examined by SEM and XRD. The results revealed that the fracture force of the SG restorations was higher than that of the CZ restorations in both cases, which ascribed to the fact that more voids and larger grains in the conventional versus in the SG restorations. The t-m phase transformation was observed only on the fracture surfaces of both materials subjected to fatigue test. Both zirconia restorations meet the clinical requirement.

  • 1875. Zhang, Yue-Biao
    et al.
    Su, Jie
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Furukawa, Hiroyasu
    Yun, Yifeng
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Gandara, Felipe
    Duong, Adam
    Zou, Xiaodong
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Yaghi, Omar M.
    Single-Crystal Structure of a Covalent Organic Framework2013In: Journal of the American Chemical Society, ISSN 0002-7863, E-ISSN 1520-5126, Vol. 135, no 44, p. 16336-16339Article in journal (Refereed)
    Abstract [en]

    The crystal structure of a new covalent organic framework, termed COF-320, is determined by single-crystal 3D electron diffraction using the rotation electron diffraction (RED) method for data collection. The COF crystals are prepared by an imine condensation of tetra-(4-anilyl)methane and 4,4'-biphenyldialdehyde in 1,4-dioxane at 120 degrees C to produce a highly porous 9-fold interwoven diamond net. COF-320 exhibits permanent porosity with a Langmuir surface area of 2400 m(2)/g and a methane total uptake of 15.0 wt % (176 cm(3)/cm(3)) at 25 degrees C and 80 bar. The successful determination of the structure of COF-320 directly from single-crystal samples is an important advance in the development of COF chemistry.

  • 1876. Zhang, Yunfan
    et al.
    Selvaraj, Rengaraj
    Kim, Younghun
    Sillanpaa, Mika
    Tai, Cheuk-Wai
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Photo-corrosion inhibition of Ag3PO4 by polyaniline coating2016In: Desalination and Water Treatment, ISSN 1944-3994, E-ISSN 1944-3986, Vol. 57, no 29, p. 13394-13403Article in journal (Refereed)
    Abstract [en]

    In this paper, polyaniline-coated silver phosphate has been successfully prepared via a facile chemisorption method in order to improve the stability of Ag3PO4 under light irradiation. The crystalline phase, band gap energy, and microstructure of the obtained PANI/Ag3PO4 composites were characterized by X-ray diffraction, UV-vis diffuse reflection spectroscopy, scanning electron microscopy, and transmission electron microscopy, respectively. The photocatalytic degradation of methlylene blue was performed to test the activities of PANI/Ag3PO4 composites with different coating amounts and the results indicate that the stabilities of PANI/Ag3PO4 composites were successfully enhanced. The correlation between photocatalytic performance and the properties of PANI/Ag3PO4 composites is discussed in detail.

  • 1877. Zhang, Yunfan
    et al.
    Selvaraj, Rengaraj
    Sillanpaa, Mika
    Kim, Younghun
    Tai, Cheuk-Wai
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    The influence of operating parameters on heterogeneous photocatalytic mineralization of phenol over BiPO42014In: Chemical Engineering Journal, ISSN 1385-8947, E-ISSN 1873-3212, Vol. 245, p. 117-123Article in journal (Refereed)
    Abstract [en]

    The photocatalytic mineralization of phenol was investigated in the presence of BiPO4 prepared by hydrothermal method. The crystal structure and morphology of synthesized sample was inspected with powder X-ray diffraction (XRD) and scanning electron microscopy (SEM), respectively. The photocatalytic activity of BiPO4 was evaluated by the degradation of phenol in a batch reactor under UV-C irradiation. In order to investigate the influence of catalyst dosage, pH value, initial concentration and additives on mineralization behavior, these key operating parameters were systematically changed during the photocatalytic process. The findings confirmed that the phenol was degraded by BiPO4 under UV-C irradiation, and the TOC (Total Organic Carbon) analysis proved that the mineralization was efficient under the optimized conditions. It is also found that the intermediate process between photocatalytic degradation and mineralization is negligibly short.

  • 1878. Zhang, Yunfan
    et al.
    Selvaraj, Rengaraj
    Sillanpää, Mika
    Kim, Younghun
    Tai, Cheuk-Wai
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Coprecipitates Synthesis of CaIn2O4 and Its Photocatalytic Degradation of Methylene Blue by Visible Light Irradiation2014In: Industrial & Engineering Chemistry Research, ISSN 0888-5885, E-ISSN 1520-5045, Vol. 53, no 29, p. 11720-11726Article in journal (Refereed)
    Abstract [en]

    Visible light-activated photocatalyst calcium indate (CaIn2O4) has been successfully prepared by a new approach with lower temperature calcinations. The sub-micrometer-sized samples were characterized by X-ray diffraction, field-emission scanning electron microscopy, energy-dispersive X-ray spectroscopy, X-ray photoelectron spectroscopy, and UV-vis diffuse reflectance spectroscopy. High-purity CaIn2O4 particles were synthesized by controlling the sintering temperature and their photocatalytic performance were evaluated. Under visible light irradiation, 10 ppm of methylene blue solution was effectively degraded in 3.0 h. The excellent photocatalytic activity of CaIn2O4 is attributed to the high purity, small particle size, and large surface area because of lower sintering temperature by thermal decomposition of metal oxalate precursor.

  • 1879. Zhang, Yunfan
    et al.
    Selvaraj, Rengaraj
    Sillanpää, Mika
    Kim, Younghun
    Tai, Cheuk-Wai
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Enhanced solar photocatalytic activity of Er3+: YAlO3-loaded BiPO4 composite2015In: Journal of Industrial and Engineering Chemistry, ISSN 1226-086X, E-ISSN 1876-794X, Vol. 24, p. 161-165Article in journal (Refereed)
    Abstract [en]

    Er3+:YAlO3 loaded BiPO4 were successfully synthesized by a simple heat treatment approach in order to enhance the photocatalytic efficiency of BiPO4. Comparing with the simple substance of BiPO4, the composite system showed the better efficiency on photodegradation of Methlyene Blue (MB) solution under a simulated solar light irradiation. The relationship between loading amount and degradation rate was also investigated. It is found that the optimal loading amount of Er3+:YAlO3 is 7 wt%. The recycling test of selected sample was carried out to study the stability of the Er3+:YAlO3 loaded BiPO4 system. The composite materials were finally characterized by field-emission scanning electron microscopy (SEM), X-ray diffraction (XRD) and UV-visible diffuse reflectance spectroscopy (UV-vis DRS). Based on the findings a possible mechanism has been proposed. The existence of luminescence agent (Er3+-doped YAlO3) and the occurrence of upconversion luminescence process have been related with the enhanced photodegradation of MB over composite system. (C) 2014 The Korean Society of Industrial and Engineering Chemistry.

  • 1880.
    Zhao, Jian
    et al.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Jonker, Sybrand J. T.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Meyer, Denise N.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Schulz, Göran
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Tran, C. Duc
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Eriksson, Lars
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Szabó, Kálmán J.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Copper-catalyzed synthesis of allenylboronic acids. Access to sterically encumbered homopropargylic alcohols and amines by propargylboration2018In: Chemical Science, ISSN 2041-6520, E-ISSN 2041-6539, Vol. 9, no 13, p. 3305-3312Article in journal (Refereed)
    Abstract [en]

    Tri- and tetrasubstituted allenylboronic acids were prepared via a new versatile copper-catalyzed methodology. The densely functionalized allenylboronic acids readily undergo propargylboration reactions with ketones and imines without any additives. Catalytic asymmetric propargylborylation of ketones is demonstrated with high stereoselectivity allowing for the synthesis of highly enantioenriched tertiary homopropargyl alcohols. The reaction is suitable for kinetic resolution of racemic allenylboronic acids affording alkynes with adjacent quaternary stereocenters.

  • 1881. Zhao, Jiao
    et al.
    Li, Mingrun
    Sun, Junliang
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Liu, Leifeng
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Su, Panpan
    Yang, Qihua
    Li, Can
    Metal-Oxide Nanoparticles with Desired Morphology Inherited from Coordination-Polymer Precursors2012In: Chemistry - A European Journal, ISSN 0947-6539, E-ISSN 1521-3765, Vol. 18, no 11, p. 3163-3168Article in journal (Refereed)
    Abstract [en]

    The “escape-by-crafty-scheme” strategy is an efficient approach to prepare metal-oxide nanomaterials with desirable morphology and crystal planes inherited from coordination-polymer nanoparticle precursors, which can be designed and finely tuned by soft chemical assembly of metal ions and organic ligands at the molecular level (see scheme; ptcda=perylene-3,4,9,10-tetracarboxylic dianhydride).

  • 1882.
    Zhao, Jing
    et al.
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK). Peking University, PR China.
    Shen, Zhijian
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK). Tsing Hua University, PR China.
    Si, Wenjie
    Wang, Xinzhi
    Bi-colored zirconia as dental restoration ceramics2013In: Ceramics International, ISSN 0272-8842, E-ISSN 1873-3956, Vol. 39, no 8, p. 9277-9283Article in journal (Refereed)
    Abstract [en]

    Machinable zirconia blocks with gradient colors are fundamental for fabrication of full-contour esthetic dental restorations. The aim of this study was to process and evaluate bi-colored zirconia ceramics as a pilot dental material by using well-established techniques. Two commercially available partially stabilized zirconia granules, one undoped and one doped with 0.202 wt% Fe2O3, resulted in white and yellow colors after sintering, respectively. Bi-colored zirconia was fabricated by two-step dry pressing of both zirconia granules one above the other to form green bodies, followed by cold isostatic pressing (CIP) and, a two-step pressureless sintering finally at 1450 degrees C. The dilatometer results showed that the Fe2O3 doped zirconia sintered slightly rapid, but the difference of shrinkage between two powders was <1%. Sintered bars achieved full density, 6.018 g/cm(3) (similar to 99%TD), without cracks in the similar to 1 mm color gradient zone. The microstructures were characterized by scanning electron microscopy (SEM) and careful observation of both surface and interior provided no obvious structural difference of either grains or pores among the three distinct regions, comprising white, yellow and color gradient zone. Vickers hardness of hi-colored zirconia was similar to 13.1 GPa, with no obvious difference in the three regions. The four-point bending strength of the hi-colored zirconia bars was 745.5 +/- 159.6 MPa, which appeared noticeably lower than that of the single-colored references being above 1000 MPa. Fractographic analysis revealed that in most of the cases (60%) the fracture was initiated at the color gradient zone, where large voids with high coordination numbers, agglomerates with critical size and concentration of irregular grains with porous surfaces were observed. Above all, bi-colored zirconia ceramics prepared by the improved technique could meet the basic requirements of dental materials. The ways of minimizing the defects within hi-colored blocks should be developed for the production of esthetic zirconia ceramics of high strength and reliability.

  • 1883.
    Zhao, Jing
    et al.
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK). Peking University School and Hospital of Stomatology, PR China.
    Wang, Xinzhi
    Si, Wenjie
    Shen, Zhijian
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK). Tsinghua University, PR China.
    Effect of resin cement selection on the microtensile bond strength of adhesively veneered 3Y-TZP2013In: Acta Odontologica Scandinavica, ISSN 0001-6357, E-ISSN 1502-3850, Vol. 71, no 5, p. 1105-1111Article in journal (Refereed)
    Abstract [en]

    Objective. The aim of this study was to investigate the effect of resin cement selection on the microtensile bond strength (mu TBS) of adhesively veneered 3Y-TZP. Materials and methods. 3Y-TZP discs were fabricated from commercial powders and treated by sandblasting and zirconia primer. Porcelain discs were sectioned from a feldspathic block and conditioned with 5% HF and silane agent. Pre-treated surfaces of zirconia and porcelain discs were bonded together using one of the three following resin cements: Multilink N (MN), Panavia F (PA) or RelyX Unicem (RU), respectively. After light-curing the joined discs were cut into microbars where 15 microbars per group were randomly chosen for mu TBS test until failure occurred (24 h storage in water in advance, crosshead speed of 0.5 mm/min). The data were analysed by one-way ANOVA and Tukey's test (p < 0.05). Fractured zirconia surfaces were examined using both a stereomicroscope and scanning electron microscope to identify the failure mode. Results. Significant differences in the mu TBS values among three groups were found (p < 0.001) and the descending order was PA, RU and MN. No zirconia or feldspathic failure occurred, but the zirconia/cement interfaces suffered from fracture for all samples. Cement cohesive failure and/or feldspathic/cement interfacial failure sometimes were involved. Failures were mainly adhesive for RU, while they were mixed for MN and PA. Conclusion. When using the adhesive veneering method, Panavia F offers better bond strength than Multilink N or RelyX Unicem, which is probably due to the content of the 10-methacryloyloxydecyl dihydrogenphosphate (10-MDP) monomer.

  • 1884.
    Zhao, Li
    et al.
    Max Planck Institute for Colloids and Interfaces, Golm.
    Bacsik, Zoltan
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Hedin, Niklas
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Wei, Wei
    Institute of Coal Chemistry, Chinese Academy of Sciences, Taiyuan.
    Sun, Yuhan
    Institute of Coal Chemistry, Chinese Academy of Sciences, Taiyuan.
    Antonietti, Markus
    Max Planck Institute for Colloids and Interfaces, Golm.
    Titirici, Maria-Magdalena
    Max Planck Institute for Colloids and Interfaces, Golm.
    Carbon Dioxide Capture on Amine-Rich Carbonaceous Materials Derived from Glucose2010In: CHEMSUSCHEM, ISSN 1864-5631, Vol. 3, p. 840-845Article in journal (Refereed)
    Abstract [en]

    The synthesis of carbonaceous materials with a high surface density of amino functions for CO2 sorption and sequestration is reported. The amino-rich carbonaceous materials are characterized by elemental analysis, N2 sorption, scanning and transmission electron microscopy, zeta potential, TGA and FTIR measurements. A detailed discussion on the use of these materials in CO2 capture is provided. The materials show significant sorption capabilities for CO2 (4.3 mmol g−1at −20 °C and 1 bar). Furthermore, they show a high apparent selectivity for CO2 over N2 at both low and high temperatures.

  • 1885. Zhao, Yingbo
    et al.
    Kornienko, Nikolay
    Liu, Zheng
    Zhu, Chenhui
    Asahina, Shunsuke
    Kuo, Tsung-Rong
    Bao, Wei
    Xie, Chenlu
    Hexemer, Alexander
    Terasaki, Osamu
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK). Korea Advanced Institute of Science & Technology (KAIST), South Korea.
    Yang, Peidong
    Yaghi, Omar M.
    Mesoscopic Constructs of Ordered and Oriented Metal-Organic Frameworks on Plasmonic Silver Nanocrystals2015In: Journal of the American Chemical Society, ISSN 0002-7863, E-ISSN 1520-5126, Vol. 137, no 6, p. 2199-2202Article in journal (Refereed)
    Abstract [en]

    We enclose octahedral silver nanocrystals (Ag NCs) in metal-organic frameworks (MOFs) to make mesoscopic constructs O-h-nano-Ag MOF in which the interface between the Ag and the MOF is pristine and the MOF is ordered (crystalline) and oriented on the Ag NCs. This is achieved by atomic layer deposition of aluminum oxide on Ag NCs and addition of a tetra-topic porphyrin-based linker, 4,4',4?,4 ''-(porphyrin-5,10,15,20-tetrayl)tetrabenzoic acid (H4TCPP), to react with alumina and make MOF [Al-2(OH)2TCPP] enclosures around Ag NCs. Alumina thickness is precisely controlled from 0.1 to 3 nm, thus allowing control of the MOF thickness from 10 to 50 nm. Electron microscopy and grazing angle X-ray diffraction confirm the order and orientation of the MOF by virtue of the porphyrin units being perpendicular to the planes of the Ag. We use surface-enhanced Raman spectroscopy to directly track the metalation process on the porphyrin and map the distribution of the metalated and unmetalated linkers on a single-nanoparticle level.

  • 1886. Zhao, Yunfeng
    et al.
    Zhang, Daliang
    Zhao, Lan
    Wang, Guangchao
    Zhu, Yihan
    Cairns, Amy
    Sun, Junliang
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK), Inorganic and Structural Chemistry.
    Zou, Xiaodong
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK), Inorganic and Structural Chemistry.
    Han, Yu
    Controlled Synthesis of the Tricontinuous Mesoporous Material IBN-9 and Its Carbon and Platinum Derivatives2011In: Chemistry of Materials, ISSN 0897-4756, E-ISSN 1520-5002, Vol. 23, no 16, p. 3775-3786Article in journal (Refereed)
    Abstract [en]

    Controlled synthesis of mesoporous materials with ultracomplicated pore configurations is of great importance for both fundamental research of nanostructures and the development of novel applications. IBN-9, which is the only tricontinuous mesoporous silica with three sets of interpenetrating three-dimensional channel systems, appears to be an excellent model mesophase for such study. The extensive study of synthesis space diagrams proves mesophase transition among the cylindrical MCM-41, tricontinuous IBN-9 and bicontinuous MCM-48, and also allows a more precise control of phase-pure synthesis. On the other hand, rational design of structure-directing agents offers a possibility to extend the synthesis conditions of IBN-9, as well as tailor its pore size. Moreover, an unprecedented helical,-structure consisting of twisted 3-fold interwoven mesoporous channels is reported here for the first time. The unique tricontinuous mesostructure of IBN-9 has been well-replicated by other functional materials (e.g., carbon and platinum) via a hard-templating synthesis route. The obtained carbon material possesses large surface area (similar to 1900 m(2)/g), high pore volume (1.56 cm(3)/g), and remarkable gas adsorption capability at both cryogenic temperatures and room temperature. The platinum material has an ordered mesostructure composed of highly oriented nanocrystals.

  • 1887. Zhao, Yunlong
    et al.
    Han, Chunhua
    Yang, Junwei
    Su, Jie
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Xu, Xiaoming
    Li, Shuo
    Xu, Lin
    Fang, Ruopian
    Jiang, Hong
    Zou, Xiaodong
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Song, Bo
    Mai, Liqiang
    Zhang, Qingjie
    Stable Alkali Metal Ion Intercalation Compounds as Optimized Metal Oxide Nanowire Cathodes for Lithium Batteries2015In: Nano letters (Print), ISSN 1530-6984, E-ISSN 1530-6992, Vol. 15, no 3, p. 2180-2185Article in journal (Refereed)
    Abstract [en]

    Intercalation of ions in electrode materials has been explored to improve the rate capability in lithium batteries and supercapacitors, due to the enhanced diffusion of Li+ or electrolyte cations. Here, we describe a synergistic effect between crystal structure and intercalated ion by experimental characterization and ab initio calculations, based on more than 20 nanomaterials: five typical cathode materials together with their alkali metal ion intercalation compounds A-M-O (A = Li, Na, K, Rb; M = V, Mo, Co, Mn, Fe-P). Our focus on nanowires is motivated by general enhancements afforded by nanoscale structures that better sustain lattice distortions associated with charge/discharge cycles. We show that preintercalation of alkali metal ions in V-O and Mo-O yields substantial improvement in the Li ion charge/discharge cycling and rate, compared to A-Co-O, A-Mn-O, and A-Fe-P-O. Diffraction and modeling studies reveal that preintercalation with K and Rb ions yields a more stable interlayer expansion, which prevents destructive collapse of layers and allow Li ions to diffuse more freely. This study demonstrates that appropriate alkali metal ion intercalation in admissible structure can overcome the limitation of cyclability as well as rate capability of cathode materials, besides, the preintercalation strategy provides an effective method to enlarge diffusion channel at the technical level, and more generally, it suggests that the optimized design of stable intercalation compounds could lead to substantial improvements for applications in energy storage.

  • 1888.
    Zhao, Zhe
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    A polymer complexing route for low temperature synthesis of Perovskite lanthanum aluminate powder2010In: Key Engineering Materials, ISSN 1013-9826, E-ISSN 1662-9795, Vol. 434 - 435, p. 863-867Article in journal (Refereed)
    Abstract [en]

    Lanthanum aluminate powders were prepared via a polymer complexing method by using PEG as complexing agent. The LaAlO3 powder was characterized by XRD and SEM. The influence of processing parameters such as molar ratio of PEG monomers to metal cations (PEG:Men+) and aging process on the phase purity and powder morphology were investigated. The calcined powder with the PEG:Men+ ratio larger than 2:1 may contain the secondary phase, namely La2O3. The formation of phase pure LaAlO3 powder occurs when the PEG:Men+ ratio is 1:1 or enough gelation time is involved. Although the phase pure powder is obtained by this PEG method, all the single phase LaAlO3 powders are found to have seriously aggregated particles. The weakly agglomerated powder morphology is only found in the powders which contain La2O3.

  • 1889.
    Zhao, Zhe
    et al.
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Wang, Cao
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Cheng, Laifei
    Northwestern Polytechnical University, Xi'an.
    Finite element modelling of temperature distribution in spark plasma sintering2010In: Key Engineering Materials, ISSN 1013-9826, E-ISSN 1662-9795, Vol. 434-435, p. 808-813Article in journal (Refereed)
    Abstract [en]

    A finite element model (FEM) is developed to simulate the temperature distribution in the sample/die/punch assembly during the spark plasma sintering (SPS) process. A thermal–electrical coupled model with temperature dependent thermal and electrical properties is implemented. The simulation studies were conducted using COMSOL and a range of heating-rates and die sizes were considered. Also, both temporary and equilibrium condition during heating process were evaluated in order to express the real temperature development in the sintering. During the spark plasma sintering process, the temperature difference between the sample center and the die surface depend on the heating-rate and die size. The simulation results also revealed that the temperature gradient during the heating process is much bigger than that in the dwelling period. It is necessary to consider the temporary state during the spark plasma sintering process in order to guarantee a well–controlled microstructure, especially in non-conductive ceramic materials.

  • 1890.
    Zheng, Haoquan
    et al.
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Gao, Feifei
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Valtchev, Valentin
    Nanosized inorganic porous materials: fabrication, modification and application2016In: Journal of Materials Chemistry A, ISSN 2050-7488, Vol. 4, no 43, p. 16756-16770Article, review/survey (Refereed)
    Abstract [en]

    Owing to their nature nanosized inorganic porous materials exhibit novel properties, different from those of bulk solids. This review highlights recent developments in the synthesis and unconventional applications of nanosized inorganic porous materials including zeolites, microporous carbons and mesoporous materials. The factors controlling the formation of nanosized inorganic porous materials are reviewed. The preparation, functionalisation, and advanced applications of nanosized inorganic porous materials in free and fixed forms are summarized. A comprehensive analysis of the emerging applications of microporous nanosized inorganic porous materials in the fields of catalysts, biomedical applications and energy-related applications is presented. Finally, the future needs and perspectives of nanosized inorganic porous solids are addressed.

  • 1891.
    Zheng, Haoquan
    et al.
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK). Shaanxi University, China.
    Svengren, Henrik
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Huang, Zhehao
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Yang, Zhiyuan
    Zou, Xiaodong
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Johnsson, Mats
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Hollow titania spheres loaded with noble metal nanoparticles for photocatalytic water oxidation2018In: Microporous and Mesoporous Materials, ISSN 1387-1811, E-ISSN 1873-3093, Vol. 264, p. 147-150Article in journal (Refereed)
    Abstract [en]

    A synthesis procedure for fabrication of hollow TiO2 spheres of mixed anatase/rutile composition loaded with noble metal nanoparticles (Au, Pt, Pd) is proposed. The materials demonstrated to be functioning photocatalysts for water oxidation. In particular nanoparticles loaded with Pd and Pt showed good catalytic activity in comparison to commercial TiO2 P25.

  • 1892.
    Zheng, Haoquan
    et al.
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Tai, Cheuk-Wai
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Su, Jie
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Zou, Xiaodong
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Gao, Feifei
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Ultra-small mesoporous silica nanoparticles as efficient carriers for pH responsive releases of anti-cancer drugs2015In: Dalton Transactions, ISSN 1477-9226, E-ISSN 1477-9234, Vol. 44, no 46, p. 20186-20192Article in journal (Refereed)
    Abstract [en]

    Mesoporous silica has emerged as one of the most promising carriers for drug delivery systems. However, the synthesis of ultra-small mesoporous silica nanoparticles (UMSNs) and their application in drug delivery remains a significant challenge. Here, spherical UMSNs (similar to 25 nm) have been synthesized and tested as drug carriers. Anti-cancer drugs mitoxantrone (MX), doxorubicin (DOX) and methotrexate (MTX) have been utilized as model drugs. The pH-responsive drug delivery system can be constructed based on electrostatic interactions between carriers and drug molecules. The UMSNs could store drugs under physiological conditions and release them under acidic conditions. Different pH-responsive release profiles were obtained in phosphate buffer solutions (PBSs) at the designed pH values (from 4.0 to 7.4). MX and DOX can be used in the pH-responsive delivery system, while MTX cannot be used. Furthermore, we found that the physiological stabilities of these drug molecules in UMSNs are in a decreasing order MX > DOX > MTX, which follows the order of their isoelectric point (pI) values.

  • 1893.
    Zheng, Haoquan
    et al.
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Zhang, Yuning
    Liu, Leifeng
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Wan, Wei
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Guo, Peng
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Nyström, Andreas M.
    Zou, Xiaodong
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    One-pot Synthesis of Metal Organic Frameworks with Encapsulated Target Molecules and Their Applications for Controlled Drug Delivery2016In: Journal of the American Chemical Society, ISSN 0002-7863, E-ISSN 1520-5126, Vol. 138, no 3, p. 962-968Article in journal (Refereed)
    Abstract [en]

    Many medical and chemical applications require target molecules to be delivered in a controlled manner at precise locations. Metal-organic frameworks (MOFs) have high porosity, large surface area, and tunable functionality and are promising carriers for such purposes. Current approaches for incorporating target molecules are based on multistep postfunctionalization. Here, we report a novel approach that combines MOF synthesis and molecule encapsulation in a one-pot process. We demonstrate that large drug and dye molecules can be encapsulated in zeolitic imidazolate framework (ZIF) crystals. The molecules are homogeneously distributed within the crystals, and their loadings can be tuned. We show that ZIF-8 crystals loaded with the anticancer drug doxorubicin (DOX) are efficient drug delivery vehicles in cancer therapy using pH-responsive release. Their efficacy on breast cancer cell lines is higher than that of free DOX. Our one-pot process opens new possibilities to construct multifunctional delivery systems for a wide range of applications.

  • 1894. Zheng, Ran
    et al.
    Han, Lei
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Pan, Qinhe
    Christensen, Kirsten E.
    Ren, Tiezhen
    Two novel Zn-MOFs: structures and characterization2012In: Acta Crystallographica Section B: Structural Science, ISSN 0108-7681, E-ISSN 1600-5740, Vol. 68, p. 158-163Article in journal (Refereed)
    Abstract [en]

    Two novel three-dimensional Zn-MOFs (zinc metal-organic frameworks), Zn5(mu 3-OH)(BTC)3(Phen)4 center dot 5H2O (denoted as HUT-11) and Zn4(mu 4-O)(BTC)2(Phen)2 center dot 4H2O (denoted as HUT-12), have been synthesized by metalligand-directed assembly under hydrothermal conditions. Here, BTC and Phen are denoted as 1,3,5-benzenetricarboxylate and phenanthroline. HUT-11 contains two kinds of secondary building units (SBUs), Zn3(mu 3-OH)(COO)5 clusters and Zn2(COO)4 clusters. This material exhibits a new three-dimensional (3,4,5)-connected topology with the Schlafli symbol (4.6.8)2(4.82)(4.64.85)(42.62.82). Two perpendicular planes cross at five coordinated Zn1-Zn3-Zn5 nodes, giving a new three-dimensional network. HUT-12 is composed of Zn4(mu 4-O)(COO)6 clusters as the secondary building units and displays a two-dimensional (3,6)-connected TiS2 related net topology with the Schlafli symbol (42.6)(44.62.88.10). Both MOFs show blue light emission and a high thermal stability above 673 K.

  • 1895. Zheng, Zhijia
    et al.
    Lu, Hui
    Bi, Han
    Lin, Xian
    Laaksonen, Aatto
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Photoluminescence properties of ZnO:Al films deposited on flexible PET substrate by RF reactive magnetron sputtering2013In: Optoelectronics and Advanced Materials Rapid Communications, ISSN 1842-6573, E-ISSN 2065-3824, Vol. 7, no 9-10, p. 676-679Article in journal (Refereed)
    Abstract [en]

    Aluminium-doped ZnO (AZO) thin films have been deposited on flexible polyethylene terephthalate (PET) substrate by RF reactive magnetron sputtering process at low substrate temperature (room -100 degrees C), and their photoluminescence (PL) behavior at room temperature and the influence of O-2:Ar ratio, substrate temperature, and deposition time were investigated. The strong near band-edge UV emission and the weak blue emission were observed, while the defect-related deep-level green emission was nearly absent, indicating that high optical quality AZO films, grown on flexible PET substrate, were obtained using the RF reactive magnetron sputtering technique. The origin of the emissions is discussed.

  • 1896. Zhong, Miao
    et al.
    Ma, Yanhang
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Oleynikov, Peter
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Domen, Kazunari
    Delaunay, Jean-Jacques
    A conductive ZnO-ZnGaON nanowire-array-on-a film photoanode for stable and efficient sunlight water splitting2014In: Energy & Environmental Science, ISSN 1754-5692, E-ISSN 1754-5706, Vol. 7, no 5, p. 1693-1699Article in journal (Refereed)
    Abstract [en]

    We report highly stable and efficient sunlight water splitting on a ZnO-ZnGaON nanowire-array-on-a-film photoanode without the assistance of any co-catalyst. The single crystalline ZnO-ZnGaON nanowirearray- on-a-film photoanode was synthesized via a high-temperature vapor-phase diffusion reaction of gallium (Ga) and nitrogen (N) on a single crystal domain ZnO nanowire-array-on-a-film structure. The synthesized ZnO-ZnGaON photoanode offers visible light absorption through N incorporation, improved electrical conductivity via Ga incorporation, and structural advantages with the high-aspect-ratio nanowire array. Compared to the chemically unstable ZnO nanowire photoanode, the ZnO-ZnGaON nanowire photoanode significantly improves the anti-photocorrosive ability for water splitting. A highly stable photocurrent density of similar to 1.5 mA cm(-2) is obtained with the ZnO-ZnGaON nanowire photoanode at an applied bias of 0.8 V-RHE under continuous sunlight illumination over five hours without noticeable degradation.

  • 1897.
    Zhong, Yuan
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Sub-grain structure in additive manufactured stainless steel 316L2017Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    The thesis focuses on exploring the sub-grain structure in stainless steel 316L prepared by additive manufacturing (AM). Two powder-bed based AM methods are involved: selective laser melting (SLM) and electron beam melting (EBM). It is already known that AM 316L has heterogeneous property and hierarchy structure: micro-sized melt pools, micro-sized grains, nano-sized sub-grain structure and nano-sized inclusions. Yet, the relation among these structures and their influence on mechanical properties have not been clearly revealed so far. Melt pool boundaries having lower amount of sub-grain segregated network structures (Cellular structure) are weaker compared to the base material. Compared with cell boundaries, grain boundaries have less influence on strength but are still important for ductility. Cell boundaries strengthen the material without losing ductility as revealed by mechanical tests. Cellular structure can be continuous across the melt pool boundaries, low angle sub-grain boundaries, but not grain boundaries. Based on the above understanding, AM process parameters were adjusted to achieve customized mechanical properties. Comprehensive characterization were carried out to investigate the density, composition, microstructure, phase, magnetic permeability, tensile property, Charpy impact property, and fatigue property of both SLM and EBM SS316L at room temperature and at elevated temperatures (250°C and 400°C). In general, SLM SS316L has better strength while EBM SS316L has better ductility due to the different process conditions. Improved cell connection between melt pools were achieved by rotating 45° scanning direction between each layer compared to rotating 90°. Superior mechanical properties (yield strength 552 MPa and elongation 83%) were achieved in SLM SS316L fabricated with 20 µm layer thickness and tested in the building direction. Y2O3 added oxide dispersed strengthening steel (ODSS) were also prepared by SLM to further improve its performance at elevated temperatures. Slightly improved strength and ductility (yield strength 574 MPa and elongation 90%) were obtained on 0.3%Y2O3-ODSS with evenly dispersed nanoparticles (20 nm). The strength drops slightly  but ductility drops dramatically at elevated temperatures. Fractographic analysis results revealed that the coalescence of nano-voids is hindered at room temperature but not at elevated temperatures. The achieved promising properties in large AM specimens assure its potential application in nuclear fusion. For the first time, ITER first wall panel parts with complex inner pipe structure were successfully fabricated by both SLM and EBM which gives great confidence to application of AM in nuclear industry. 

  • 1898.
    Zhong, Yuan
    et al.
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Liu, Leifeng
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Wikman, Stefan
    Cui, Daqing
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Shen, Zhijian
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Intragranular cellular segregation network structure strengthening 316L stainless steel prepared by selective laser melting2016In: Journal of Nuclear Materials, ISSN 0022-3115, E-ISSN 1873-4820, Vol. 470, p. 170-178Article in journal (Refereed)
    Abstract [en]

    A feasibility study was performed to fabricate ITER In-Vessel components by Selective Laser Melting (SLM) supported by Fusion for Energy (F4E). Almost fully dense 316L stainless steel (SS316L) components were prepared from gas-atomized powder and with optimized SLM processing parameters. Tensile tests and Charpy-V tests were carried out at 22 degrees C and 250 degrees C and the results showed that SLM SS316L fulfill the RCC-MR code. Microstructure characterization reveals the presence of hierarchical macro-, micro- and nano-structures in as-built samples that were very different from SS316L microstructures prepared by other established methods. The formation of a characteristic intragranular cellular segregation network microstructure appears to contribute to the increase of yield strength without losing ductility. Silicon oxide nano-inclusions were formed during the SLM process that generated a micro-hardness fluctuation in the building direction. The combined influence of a cellular microstructure and the nano-inclusions constraints the size of ductile dimples to nano-scale. The crack propagation is hindered by a pinning effect that improves the defect-tolerance of the SLM SS316L. This work proves that it was possible to manufacture SS316L with properties suitable for ITER First Wall panels. Further studies on irradiation properties of SLM SS316L and manufacturing of larger real-size components are needed.

  • 1899.
    Zhong, Yuan
    et al.
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Liu, Leifeng
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Zou, Ji
    Kvetkova, Lenka
    Lofaj, Frantisk
    Wang, Dianzheng
    Olsén, Jon
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Cui, Daqing
    Shen, Zhijian
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Manipulating the sub-grain cellular network structure during selective laser meltingManuscript (preprint) (Other academic)
  • 1900.
    Zhong, Yuan
    et al.
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Liu, Leifeng
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Zou, Ji
    Li, Xiaodong
    Olsén, Jon
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Cui, Daqing
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Shen, Zhijian
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Oxide dispersion strengthened austenitic steel prepared by selective laser melting with superior strength and ductilityManuscript (preprint) (Other academic)
353637383940 1851 - 1900 of 1954
CiteExportLink to result list
Permanent link
Cite
Citation style
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf