| 11. |
- Lin, Qibin, et al.
(författare)
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Strength and failure characteristics of jointed rock mass with double circular holes under uniaxial compression : Insights from discrete element method modelling
- 2020
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Ingår i: Theoretical and applied fracture mechanics (Print). - : Elsevier. - 0167-8442 .- 1872-7638. ; 109
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Tidskriftsartikel (refereegranskat)abstract
- Underground projects are typically performed in nonpersistent jointed rock masses. Excavation of tunnels or chambers causes crack initiation, propagation and coalescence, resulting in the instability and destruction of surrounding rocks. The failure behaviour of rocks is complicated owing to the interaction between holes and joints. Therefore, understanding the failure characteristics of holes in jointed rock masses is essential. In this paper, the mechanical characteristics of a jointed rock mass with double circular holes under uniaxial loading was investigated using the discrete element method. The effects of different joint parameters on the strength and failure behaviour of the jointed rock mass with double circular holes were studied. The results show that the existence of joints degrades the mechanical behaviour of the rock mass. Specifically, the peak strength and elastic modulus of the specimens show a “U” shape change with the joint dip angle and reach the minimum value when the angle is 30°. With an increase in joint spacing, the peak strength and elastic modulus increase gradually. An investigation of the crack coalescence process and displacement field of the specimens reveal the crack propagation mechanism based on the interaction between holes and joints under uniaxial loading. Five types of crack coalescence among the holes and adjacent joints were summarized. Four typical failure modes were observed: tensile failure across joints, block rotation failure around holes, shear failure through joint planes and tensile–shear mixed failure through holes.
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| 12. |
- Svensson Grape, Erik, et al.
(författare)
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Breathing Metal-Organic Framework Based on Flexible Inorganic Building Units
- 2020
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Ingår i: Crystal Growth & Design. - : American Chemical Society (ACS). - 1528-7483 .- 1528-7505. ; 20:1, s. 320-329
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Tidskriftsartikel (refereegranskat)abstract
- Five novel bismuth carboxylate coordination polymers were synthesized from biphenyl-3,4′,5-tricarboxylic acid (H3BPT) and [1,1′:4′,1′′]terphenyl-3,3′′,5,5′′-tetracarboxylic acid (H4TPTC). One of the phases, [Bi(BPT)]·2MeOH (denoted SU-100, as synthesized), is the first example, to the best of our knowledge, of a reversibly flexible bismuth-based metal–organic framework. The material exhibits continuous changes to its unit cell parameters and pore shape depending on the solvent it is immersed in and the dryness of the sample. Typically, in breathing carboxylate-based MOFs, flexibility occurs through tilting of the organic linkers without significantly altering the coordination environment around the cation. In contrast to this, the continuous breathing mechanism in SU-100 involves significant changes to bond angles within the Bi2O12 inorganic building unit (IBU). The flexibility of the IBU of SU-100 reflects the nondiscrete coordination geometry of the bismuth cation. A disproportionate increase in the solvent accessible void volume was observed when compared to the expansion of the unit cell volume of SU-100. Additionally, activated SU-100 (SU-100-HT) exhibits a large increase in unit cell volume, yet has the smallest void volume of all the studied samples.
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| 13. |
- Xu, Heng, et al.
(författare)
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Editorial: Some Thoughts on Reviewing for Information Systems Research and Other Leading Information Systems Journals
- 2023
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Ingår i: Information Systems Research. - : INFORMS. - 1526-5536 .- 1047-7047. ; 34:4, s. 1321-1338
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- Peer review of research before publication is both an essential and an integral part of scientific knowledge production. For reputable journals, the peer review process distinguishes knowledge claims in journal articles from those in sources with unknown or varying veracity. The peer review process assures readers that the published work is credible (i.e., conducted in line with prescribed norms of research) and meets a certain threshold with respect to contributions and potential impact. Leading journals are perceived as such not only because the best research is submitted to them but also because of the efforts of the best reviewers and editors in evaluating and, when applicable, developing the initially submitted manuscripts1 to publishable form. The sustained quality of reviews is critical for journals such as Information Systems Research (ISR). With the number of submissions to ISR growing each year, as well as an explicit policy of encouraging and celebrating inclusive excellence (Sarker 2023), there is a need for more reviewers for the journal (and the discipline, more generally) who have the necessary expertise to evaluate submitted papers, who understand and are attuned to the norms of the different traditions and genres of work submitted, and who know how to craft reviews that ensure the review process supports effective knowledge production. In this editorial, we draw on the expertise of some of the experienced associate editors (AEs) at ISR2 who represent different research traditions to provide guidance on how ISR reviewers can contribute reviews that AEs and authors are likely to find valuable. The primary audience of this editorial is Ph.D. students and early career scholars who occasionally review for, or seek to review for, ISR and similar journals. Although experienced reviewers likely know most of what we will say in the next few pages, we are hopeful that the editorial can provide a useful recapitulation of characteristics of reviews that are appreciated by ISR editors, irrespective of the reviewers’ experience. Finally, revisiting what reviewers look for in manuscripts can prove helpful for authors submitting papers to journals such as ISR. Before proceeding, we would like to acknowledge the efforts of editors and editorial board members from various journals who have organized reviewer development workshops (e.g., Rai 2019, Whitley 2023), and reflections on the review process and effective reviews by notable scholars in our discipline (e.g., Lee 1995; Saunders 2005a, b; Straub 2009; Kohli and Straub 2011; Davison 2015; Rai 2016; Leidner et al. 2022); see Table 1. Our editorial does not seek to supplant this accumulated wisdom but seeks to add nuances to the various guidelines that have been offered in the past. We illustrate key points with examples from various research traditions.
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| 14. |
- Zhao, Jingjing, et al.
(författare)
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A simple pressure-assisted method for MicroED specimen preparation
- 2021
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Ingår i: Nature Communications. - : Springer Science and Business Media LLC. - 2041-1723. ; 12:1
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Tidskriftsartikel (refereegranskat)abstract
- Micro-crystal electron diffraction (MicroED) has shown great potential for structure determination of macromolecular crystals too small for X-ray diffraction. However, specimen preparation remains a major bottleneck. Here, we report a simple method for preparing MicroED specimens, named Preassis, in which excess liquid is removed through an EM grid with the assistance of pressure. We show the ice thicknesses can be controlled by tuning the pressure in combination with EM grids with appropriate carbon hole sizes. Importantly, Preassis can handle a wide range of protein crystals grown in various buffer conditions including those with high viscosity, as well as samples with low crystal concentrations. Preassis is a simple and universal method for MicroED specimen preparation, and will significantly broaden the applications of MicroED.
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| 15. |
- Zhao, Jingjing, 1988-
(författare)
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Push the limitations of crystal structure determination by 3D electron diffraction : From inorganic porous materials to biomolecules
- 2021
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Structure elucidation is fundamental to understanding the chemical and physical properties of a material. Three-dimensional electron diffraction (3D ED) has shown great power for structure determination of nanometer- or submicrometer-sized crystals that are either too small or too complex for X-ray diffraction. 3D ED can be applied to a wide range of crystalline materials from inorganic materials, small organic molecules, to macromolecules. In this thesis, continuous rotation electron diffraction (cRED), also known as micro-crystal electron diffraction (MicroED) in macromolecular crystallography, has been applied for the determination of interesting novel crystal structures. New methods and protocols have been developed to push the current limitations of crystal structure determination by 3D ED.The structure of silicate zeolite PST-24 is highly disordered. A combination of cRED with high-resolution transmission electron microscopy (HRTEM) revealed its unique channel system with varying dimensionality from 2D to 3D. The aluminum metal-organic framework CAU-23 nanocrystals form aggregates and are very beam sensitive. Its structure, as determined by cRED, is built by twisted helical Al-O chains connected by TDC2- linkers, forming a chiral structure with square channels. The unique structure of CAU-23 provides high stability and high water adsorption capacity, making it an ideal material for ultra-low temperature adsorption driven chillers.A simple pressure-assisted specimen preparation method, denoted Preassis, has been developed to overcome the challenges in the application of MicroED on biological samples with high viscosity and low crystal concentration. It has been successfully applied for the specimen preparation of several bio-molecular crystals including a novel R2lox metalloenzyme, which was crucial for its structure determination. Furthermore, an investigation of the influence of radiation damage on lysozyme crystals was performed to improve the data quality and final structural model. Finally, the crystal structure of acetylated amyloid-β fragment Ac-Aβ16-20, related to Alzheimer’s disease, has been studied. The crystal has an active optical wave-guiding property with an excitation wavenumber of 488 nm due to its unique packing of Ac-KLVFF β–sheets.
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