Background: Influenza virus NA is transported to the host cell surface. Results: Cdc42 promotes the transport of NA to the plasma membranes, whereas ARHGAP21 inhibits this process. Conclusion: Cdc42 positively and ARHGAP21 negatively regulate NA transport to the cell surface and virus replication. Significance: Identification of host factors involved in regulating NA transport is critical for understanding influenza virus replication.
A method is introduced joining together forward-scattering diffraction data taken in a small angular window at different photoelectron energies. This method extends the usable range in phase space for three-dimensional image reconstruction. Examples based on theoretical simulations demonstrate that a spatial resolution of < 1 A is achievable. We also show that using a small angular window in the backscattering geometry eliminates splittings in the reconstructed image.PACS numbers: 68.35.Bs, 68.55.-a When forming three-dimensional atomic images from electron-emission holography [1][2][3][4][5], there are two objectives: (i) that the images are formed at the correct atomic positions and (ii) that the full width at half magnitude (FWHM) of the image is as small as possible. The FWHM defines the ability of a "microscope" to produce distinct images of two closely spaced objects. The best resolution of the current state-of-the-art conventional electron microscope is 2-3 A. In electron-emission holography, a limiting factor is the small angular range of usable data available in k space for image reconstruction. In the forward-scattering geometry, most systems have multiple focusing directions [6]. In such systems, the diffraction fringes in an angular cone around each focusing direction are dominated by the scattering of atoms situated along that particular direction [7,8]. Therefore, the relevant interference fringes for image reconstruction for atoms in a particular direction are limited to within the effective angular cone O r , which is much smaller than the full 0,2* opening [7,9]. In the backscattering geometry, deep cusps in the scattering factor of many materials limit the effective angular range to a small cone in the reconstruction process. As we shall see later, these cusps cause image peaks to be split [10]. Since the diffraction limit for resolution is Ar a =2.4;r/Afc«, where a is a Cartesian-coordinate index, the small range of applicable Ak limits the achievable spatial resolution.In this paper, we show how this serious limitation of the technique can be lifted through the use of multiple energies in which diffraction data in a given angular cone taken at different emission energies are connected to form an extended range. When used in conjunction with a variable energy source (e.g., a synchrotron radiation center or Kikuchi electrons), this method can reach a spatial resolution of less than 1 A in the direction of the emitter scatterer. This direction has a worse resolution (> 2.5 A) in single-energy image reconstructions [2-6, 9,10].For the purpose of image reconstruction, we use x-rayphotoemission-spectroscopy (XPS) diffraction spectra calculated by the multiple-scattering slab method in which the crystal is rotated while the directions of photon incidence and electron exit are held fixed. This collection mode eliminates the anisotropy in the unscattered wave from any initial atomic core level [9]. Since the reference wave in this collection mode is continuously varying, we introduce an image reconstr...
Mass transfer of guest molecules has a significant impact on the applications of nanoporous crystalline materials and particularly shape-selective catalysis over zeolites. Control of mass transfer to alter reaction over zeolites, however, remains an open challenge. Recent studies show that, in addition to intracrystalline diffusion, surface barriers represent another transport mechanism that may dominate the overall mass transport rate in zeolites. We demonstrate that the methanol-to-olefins (MTO) reaction can be modulated by regulating surface permeability in SAPO-34 zeolites with improved chemical liquid deposition and acid etching. Our results explicitly show that the reduction of surface barriers can prolong catalyst lifetime and promote light olefins selectivity, which opens a potential avenue for improving reaction performance by controlling the mass transport of guest molecules in zeolite catalysis.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.