| 1. |
- Beal, Jacob, et al.
(author)
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Robust estimation of bacterial cell count from optical density
- 2020
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In: Communications Biology. - : Springer Science and Business Media LLC. - 2399-3642. ; 3:1
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Journal article (peer-reviewed)abstract
- Optical density (OD) is widely used to estimate the density of cells in liquid culture, but cannot be compared between instruments without a standardized calibration protocol and is challenging to relate to actual cell count. We address this with an interlaboratory study comparing three simple, low-cost, and highly accessible OD calibration protocols across 244 laboratories, applied to eight strains of constitutive GFP-expressing E. coli. Based on our results, we recommend calibrating OD to estimated cell count using serial dilution of silica microspheres, which produces highly precise calibration (95.5% of residuals <1.2-fold), is easily assessed for quality control, also assesses instrument effective linear range, and can be combined with fluorescence calibration to obtain units of Molecules of Equivalent Fluorescein (MEFL) per cell, allowing direct comparison and data fusion with flow cytometry measurements: in our study, fluorescence per cell measurements showed only a 1.07-fold mean difference between plate reader and flow cytometry data.
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| 2. |
- Chen, Hong, et al.
(author)
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PKU-3 : An HCI-Inclusive Aluminoborate for Strecker Reaction Solved by Combining RED and PXRD
- 2015
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In: Journal of the American Chemical Society. - : American Chemical Society (ACS). - 0002-7863 .- 1520-5126. ; 137:22, s. 7047-7050
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Journal article (peer-reviewed)abstract
- A novel microporous aluminoborate, denoted as PKU-3, was prepared by the boric acid flux method. The structure of PKU-3 was determined by combining the rotation electron diffraction and synchrotron powder X-ray diffraction data with well resolved ordered Cl- ions in the channel. Composition and crystal structure analysis showed that there are both proton and chlorine ions in the channels. Part of these protons and chlorine ions can be washed away by basic solutions to activate the open pores. The washed PKU-3 can be used as an efficient catalyst in the Strecker reaction with yields higher than 90%.
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| 3. |
- Chen, Yanping, et al.
(author)
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PKU-20 : A new silicogermanate constructed from sti and asv layers
- 2016
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In: Microporous and Mesoporous Materials. - : Elsevier BV. - 1387-1811 .- 1873-3093. ; 224, s. 384-391
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Journal article (peer-reviewed)abstract
- A new silicogermanate (PKU-20) was hydrothermally synthesized using triethylisopropylammonium cation as the structure directing agent in the presence of fluoride. Its structure was determined from a combination of synchrotron single crystal X-ray diffraction and powder X-ray diffraction data. PKU-20 crystallizes in the monoclinic space group C2/m, with the lattice parameters of a = 18.5901(6) angstrom, b = 13.9118 (4) angstrom, c = 22.2614(7) angstrom and beta = 100.1514 (12)degrees. The framework of PKU-20 is constructed from an alternate stacking of sti and asv layers. The sti layer is exactly the same as that in the STI framework, while the asv layer is a new layer sliced off from the ASV framework parallel to the (112) plane. The takeout scheme of the layer is discussed on the basis of a composite building unit D4R-/au-D4R. PKU-20 possesses a two-dimensional channel system, where the 10-ring channels parallel to the [010] direction are intercrossed by 12-ring pockets along the [101] direction.
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| 4. |
- Li, Jian, et al.
(author)
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Discovery of Complex Metal Oxide Materials by Rapid Phase Identification and Structure Determination
- 2019
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In: Journal of the American Chemical Society. - : American Chemical Society (ACS). - 0002-7863 .- 1520-5126. ; 141:12, s. 4990-4996
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Journal article (peer-reviewed)abstract
- The discovery of new inorganic functional materials is of fundamental importance in synthetic and materials science. In the past, the discovering new materials relied on a slow and serendipitous trial-and-error process, especially in the well-studied oxide systems. Here, we presented a strategy to shorten the period of discovery of new complex metal oxide materials by rapid phase identification and structure determination with 3D electron diffraction (ED) techniques, which do not require pure samples or single crystal growth. With such strategy, three new complex metal oxide materials (BiTi0.855Fe1.145O4.93, BiTi4FeO11 and BiTi2FeO7) were discovered in the simple ternary Bi2O3-Fe2O3-TiO2 system. To our best knowledge, it is the first time to discover three new complex metal oxide materials with new structure types in a single study of ternary metal oxide system. The structures of new materials were refined by combining powder X-ray diffraction (PXRD) with powder neutron diffraction (PND). The most striking feature in this system is that BiTi0.855Fe1.145O4.93 presents edge-shared five-coordinated iron/titanium polyhedra. In addition, another new phase BiTi4GaO11, which is isostructural with BiTi4FeO11, can be obtained when replacing Fe in BiTi4FeO11 with Ga. The band structure investigation of BiTi0.855Fe1.145O4.93, BiTi4FeO11, BiTi2FeO7 and BiTi4GaO11 shown that they were semiconductors with band gaps of 1.65, 2.0, 1.9, and 2.8 eV, respectively. Although this study focused on rapid developing of new inorganic functional materials, this method for developing new materials is available to all fields in chemistry and material chemistry where the limiting factors are impurity, submicrometersized crystals, etc.
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| 5. |
- Li, Jian, et al.
(author)
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Modulated structure determination and ion transport mechanism of oxide-ion conductor CeNbO4+δ
- 2020
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In: Nature Communications. - : Springer Science and Business Media LLC. - 2041-1723. ; 11:1
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Journal article (peer-reviewed)abstract
- CeNbO4+δ, a family of oxygen hyperstoichiometry materials with varying oxygen content (CeNbO4, CeNbO4.08, CeNbO4.25, CeNbO4.33) that shows mixed electronic and oxide ionic conduction, has been known for four decades. However, the oxide ionic transport mechanism has remained unclear due to the unknown atomic structures of CeNbO4.08 and CeNbO4.33. Here, we report the complex (3 + 1)D incommensurately modulated structure of CeNbO4.08, and the supercell structure of CeNbO4.33 from single nanocrystals by using a three-dimensional electron diffraction technique. Two oxide ion migration events are identified in CeNbO4.08 and CeNbO4.25 by molecular dynamics simulations, which was a synergic-cooperation knock-on mechanism involving continuous breaking and reformation of Nb2O9 units. However, the excess oxygen in CeNbO4.33 hardly migrates because of the high concentration and the ordered distribution of the excess oxide ions. The relationship between the structure and oxide ion migration for the whole series of CeNbO4+δ compounds elucidated here provides a direction for the performance optimization of these compounds.
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| 6. |
- Liang, Lin, et al.
(author)
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Non-Interpenetrated Single-Crystal Covalent Organic Frameworks
- 2020
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In: Angewandte Chemie International Edition. - : Wiley. - 1433-7851 .- 1521-3773. ; 59:41, s. 17991-17995
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Journal article (peer-reviewed)abstract
- Growth of covalent organic frameworks (COFs) as single crystals is extremely challenging. Inaccessibility of open-structured single-crystal COFs prevents the exploration of structure-oriented applications. Herein we report for the first time a non-interpenetrated single-crystal COF, LZU-306, which possesses the open structure constructed exclusively via covalent assembly. With a high void volume of 80 %, LZU-306 was applied to investigate the intrinsic dynamics of reticulated tetraphenylethylene (TPE) as the individual aggregation-induced-emission moiety. Solid-state(2)H NMR investigation has determined that the rotation of benzene rings in TPE, being the freest among the reported cases, is as fast as 1.0x10(4) Hz at 203 K to 1.5x10(7) Hz at 293 K. This research not only explores a new paradigm for single-crystal growth of open frameworks, but also provides a unique matrix-isolation platform to reticulate functional moieties into a well-defined and isolated state.
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| 7. |
- Lin, Junzhong, et al.
(author)
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Hierarchical MFI zeolite synthesized via regulating the kinetic of dissolution-recrystallization and their catalytic properties
- 2018
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In: Catalysis communications. - : Elsevier BV. - 1566-7367 .- 1873-3905. ; 115, s. 82-86
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Journal article (peer-reviewed)abstract
- Hierarchical MFI zeolites with open pores were synthesized by a temperature programmed dissolution-recrystallization post-treatment. By controlling the temperature of post-treatment using TPAOH, open macropores and mesopores were created by simply regulating the kinetics of dissolution and recrystallization. Benzyl alcohol self-etherification reaction, which only occurs in micropores, was tested on ZSM-5 to understand the effect of hierarchical pore system. The catalytic activity of hierarchical TS-1 was tested with cyclohexanone ammoximation. Hierarchical ZSM-5 and TS-1 zeolites with open pores showed higher catalytic activity compared with both hollow and conventional ones. The increased catalytic activities can be ascribed to the enhanced diffusion.
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| 8. |
- Lin, Jia, et al.
(author)
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Pressure-induced semiconductor-to-metal phase transition of a charge-ordered indium halide perovskite
- 2019
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In: Proceedings of the National Academy of Sciences of the United States of America. - : Proceedings of the National Academy of Sciences. - 0027-8424 .- 1091-6490. ; 116:47, s. 23404-23409
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Journal article (peer-reviewed)abstract
- Phase transitions in halide perovskites triggered by external stimuli generate significantly different material properties, providing a great opportunity for broad applications. Here, we demonstrate an In-based, charge-ordered (In+/In3+) inorganic halide perovskite with the composition of Cs2In(I)In(III)Cl-6 in which a pressure-driven semiconductor-to-metal phase transition exists. The single crystals, synthesized via a solid-state reaction method, crystallize in a distorted perovskite structure with space group I4/m with a = 17.2604(12) angstrom, c = 11.0113(16) angstrom if both the strong reflections and superstructures are considered. The supercell was further confirmed by rotation electron diffraction measurement. The pressure-induced semiconductor-to-metal phase transition was demonstrated by high-pressure Raman and absorbance spectroscopies and was consistent with theoretical modeling. This type of charge-ordered inorganic halide perovskite with a pressure-induced semiconductor-to-metal phase transition may inspire a range of potential applications.
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| 9. |
- Meng, Qingpeng, et al.
(author)
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Zeolite A synthesized from alkaline assisted pre-activated halloysite for efficient heavy metal removal in polluted river water and industrial wastewater
- 2017
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In: Journal of Environmental Sciences(China). - : Elsevier BV. - 1001-0742 .- 1878-7320. ; 56, s. 254-262
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Journal article (peer-reviewed)abstract
- High quality zeolite A was synthesized through a hydrothermal process using alkaline-assisted pre-activated halloysite mineral as the alumina and silica source. The synthesis conditions employed in this study were finely tuned by varying the activating temperature, sodium hydroxide content, water content and Si/Al ratio. The obtained zeolite A showed excellent adsorption properties for both single metal cation solutions and mixed cation solutions when the concentrations of the mixed cations were comparable with those in polluted natural river water and industrial wastewater. High adsorptive capacities for Ag+ (123.05 mg/g) and Pb2+ (227.70 mg/g) were achieved using the synthesized zeolite A. This observation indicates that the zeolite A synthesized from alkaline-assisted pre-activated halloysite can be used as a low-cost and relatively effective adsorbent to purify heavy metal cation polluted natural river water and industrial wastewater.
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| 10. |
- Xu, Hai-Sen, et al.
(author)
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Single crystal of a one-dimensional metallo-covalent organic framework
- 2020
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In: Nature Communications. - : Springer Science and Business Media LLC. - 2041-1723. ; 11:1
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Journal article (peer-reviewed)abstract
- Although polymers have been studied for well over a century, there are few examples of covalently linked polymer crystals synthesised directly from solution. One-dimensional (1D) covalent polymers that are packed into a framework structure can be viewed as a 1D covalent organic framework (COF), but making a single crystal of this has been elusive. Herein, by combining labile metal coordination and dynamic covalent chemistry, we discover a strategy to synthesise single-crystal metallo-COFs under solvothermal conditions. The single-crystal structure is rigorously solved using single-crystal electron diffraction technique. The non-centrosymmetric metallo-COF allows second harmonic generation. Due to the presence of syntactic pendant amine groups along the polymer chains, the metallopolymer crystal can be further cross-linked into a crystalline woven network. Although polymers have been studied for well over a century, there are few examples of covalently linked polymer crystals synthesized directly from solution. Here, the authors demonstrate a strategy to synthesize single crystalline 1D metallo-covalent organic frameworks by combining dynamic covalent chemistry and metal-ligand coordination.
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