scholarly journals Off-axis electron holography of bacterial cells and magnetic nanoparticles in liquid

2017 ◽  
Vol 14 (135) ◽  
pp. 20170464 ◽  
Author(s):  
Tanya Prozorov ◽  
Trevor P. Almeida ◽  
András Kovács ◽  
Rafal E. Dunin-Borkowski
Keyword(s):  
Magnetic Nanoparticles ◽  
Electrostatic Potentials ◽  
Double Layers ◽  
Electron Holography ◽  
Bacterial Cells ◽  
Fringe Contrast ◽  
Specimen Holder ◽  
Pass Through ◽  
Scientific Phenomena ◽  
Fluid Cell

The mapping of electrostatic potentials and magnetic fields in liquids using electron holography has been considered to be unrealistic. Here, we show that hydrated cells of Magnetospirillum magneticum strain AMB-1 and assemblies of magnetic nanoparticles can be studied using off-axis electron holography in a fluid cell specimen holder within the transmission electron microscope. Considering that the holographic object and reference wave both pass through liquid, the recorded electron holograms show sufficient interference fringe contrast to permit reconstruction of the phase shift of the electron wave and mapping of the magnetic induction from bacterial magnetite nanocrystals. We assess the challenges of performing in situ magnetization reversal experiments using a fluid cell specimen holder, discuss approaches for improving spatial resolution and specimen stability, and outline future perspectives for studying scientific phenomena, ranging from interparticle interactions in liquids and electrical double layers at solid–liquid interfaces to biomineralization and the mapping of electrostatic potentials associated with protein aggregation and folding.

Is there an electron wind?

1990 ◽  
Vol 48 (4) ◽  
pp. 798-799
Author(s):  
L. D. Marks ◽  
J. P. Zhang
Keyword(s):  
Electron Microscopy ◽  
High Resolution Electron Microscopy ◽  
Zone Axis ◽  
Electron Holography ◽  
Electron Wave ◽  
Small Particles ◽  
Resolution Electron ◽  
Pass Through ◽  
Electron Wind ◽  
Inelastic Scatter

A not uncommon question in electron microscopy is what happens to the momentum transferred by the electron beam to a crystal. If the beam passes through a crystal and is preferentially diffracted in one direction, is the momentum ’lost’ by the beam transferred to the crystal? Newton’s third law implies that this must be the case. Some experimental observations also indicate that this is the case; for instance, with small particles if the particles are supported on the top surface of a film they often do not line up on the zone axis, but if they are on the bottom they do. However, if momentum is transferred to the crystal, then surely we are dealing with inelastic scattering, not elastic scattering and is not the scattering probability different? In addition, normally we consider inelastic scatter as incoherent, and therefore the part of the electron wave that is inelastically scattered will not coherently interfere with the part of the wave that is scattered; but, electron holography and high resolution electron microscopy work so the wave passing through a specimen must be coherent with the wave that does not pass through the specimen.

Electromigration of Charged Polystyrene Beads Through Silicon Nanopores Filled With Low Ionic Strength Solutions

2009 ◽  
Author(s):  
Punarvasu Joshi ◽  
Trupthi Mathew ◽  
Leo Petrossian ◽  
Shalini Prasad ◽  
Michael Goryll ◽  
...  
Keyword(s):  
Ionic Strength ◽  
Double Layers ◽  
Electric Double Layers ◽  
Ionic Solution ◽  
Polystyrene Beads ◽  
Detailed Statistical Analysis ◽  
Charge Interaction ◽  
Pass Through ◽  
Low Ionic Strength ◽  
Bulk Behavior

In this work we present preliminary results demonstrating the influence of electrical double layer overlap on the electromigration of polystyrene beads (PSB) through an array of 25 cylindrical nanopores. Each of the cylindrical nanopores of the array used in this study is 360nm long with a diameter of 90nm. We observe frequent Coulter events for solutions of higher ionic strength and absence of Coulter events at low ionic strength solution. At higher ionic strengths, the electric double layers in the nanopore are thin and ion transport through the nanopore follows the bulk behavior of the ionic solution. For solutions of lower ionic strength, the electric double layers are comparable to the nanopore dimensions and start to overlap, suggesting surface charge interaction with the polystyrene beads that pass through the nanopore. The work continues towards detailed statistical analysis of the characteristic events observed for different concentrations.

An Ultra-High-Tilt Two-Contact Electrical Biasing Specimen Holder for Electron Holography and Electron Tomography of Semiconductor Devices

2004 ◽  
Vol 10 (S02) ◽  
pp. 1012-1013 ◽  
Author(s):  
Rafal E Dunin-Borkowski ◽  
Alison C Twitchett ◽  
Jonathan S Barnard ◽  
Ronald F Broom ◽  
Paul A Midgley ◽  
...  
Keyword(s):  
Electron Tomography ◽  
Semiconductor Devices ◽  
Electron Holography ◽  
Specimen Holder

Extended abstract of a paper presented at Microscopy and Microanalysis 2004 in Savannah, Georgia, USA, August 1–5, 2004.

scholarly journals A Convenient Colorimetric Bacteria Detection Method Utilizing Chitosan-Coated Magnetic Nanoparticles

Nanomaterials ◽  
2020 ◽  
Vol 10 (1) ◽  
pp. 92 ◽  
Author(s):  
Thao Nguyen Le ◽  
Tai Duc Tran ◽  
Moon Il Kim
Keyword(s):  
Magnetic Nanoparticles ◽  
Bacterial Infections ◽  
Colorimetric Assay ◽  
Point Of Care ◽  
Bacterial Cells ◽  
Diammonium Salt ◽  
Iron Oxide Magnetic Nanoparticles ◽  
Novel Strategy ◽  
Positively Charged ◽  
Timely Treatment

An effective novel strategy to detect bacteria is promising because it may improve human health by allowing early diagnosis and timely treatment of bacterial infections. Here, we report a simple, reliable, and economical colorimetric assay using the peroxidase-like activity of chitosan-coated iron oxide magnetic nanoparticles (CS-MNPs). When CS-MNPs are incubated with a sample containing bacterial cells such as the gram-negative Escherichia coli or the gram-positive Staphylococcus aureus, the negatively-charged bacterial membrane interacts with positively-charged chitosan on the surface of CS-MNPs, thus resulting in significant reduction of their peroxidase-like activity presumably by a hindrance in the accessibility of the negatively charged substrate, 2-2′-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) diammonium salt (ABTS) to the positively-charged CS-MNPs. This simple colorimetric strategy allowed the rapid detection of bacterial cells down to 104 CFU mL−1 by the naked eye and 102 CFU mL−1 by spectrophotometry within 10 min. Based on the results, we anticipate that the CS-MNPs-based assay has great potential for the on-site diagnosis of bacterial infections in facility-limited or point-of-care testing (POCT) environments.

Off-axis electron holography of electrostatic potentials in unbiased and reverse biased focused ion beam milled semiconductor devices

2004 ◽  
Vol 214 (3) ◽  
pp. 287-296 ◽  
Author(s):  
A. C. TWITCHETT ◽  
R. E. DUNIN-BORKOWSKI ◽  
R. J. HALLIFAX ◽  
R. F. BROOM ◽  
P. A. MIDGLEY
Keyword(s):  
Focused Ion Beam ◽  
Ion Beam ◽  
Semiconductor Devices ◽  
Electrostatic Potentials ◽  
Electron Holography

Surface electrostatic potentials in carbon nanotubes and graphene membranes investigated with electron holography

Carbon ◽  
2011 ◽  
Vol 49 (4) ◽  
pp. 1423-1429 ◽  
Author(s):  
Luca Ortolani ◽  
Florent Houdellier ◽  
Marc Monthioux ◽  
Etienne Snoeck ◽  
Vittorio Morandi
Keyword(s):  
Carbon Nanotubes ◽  
Electrostatic Potentials ◽  
Electron Holography ◽  
Surface Electrostatic Potentials ◽  
Graphene Membranes

Revision of Ferroelastic Structures of n-Heptyl- and n-Octylammonium Dihydrogen Phosphate Crystals

1997 ◽  
Vol 53 (2) ◽  
pp. 272-279 ◽  
Author(s):  
J. Fábry ◽  
V. Petrícek ◽  
I. Císarová ◽  
J. Kroupa
Keyword(s):  
Hydrogen Bond ◽  
Hydrogen Bonds ◽  
Structure Determination ◽  
Symmetry Operation ◽  
Double Layers ◽  
Dihydrogen Phosphate ◽  
Hydrogen Bond Acceptor ◽  
Space Group ◽  
Unit Cells ◽  
Pass Through

This study deals with the structure determination of C7H15NH3 +.H2PO4 − (C7ADP) and C8H17NH3 +.H2PO4 − (C8ADP). The samples used in this study were not subjected to a phase transition after they had been crystallized. Unlike a previous structure determination, weak reflections, now with indices h = 2n + 1, were included. This means that both structures are described in unit cells with the lattice parameters a twice as long as given previously. Both structures are quite similar; two double layers of dihydrogen phosphates, which are interconnected by hydrogen bonds (2.52–2.62 Å), pass through each unit cell. Alkylammonium groups interact with these dihydrogen phosphates via longer hydrogen bonds (>2.75 Å), while the rest of the aliphatic chains interact via van der Waals contacts. All H atoms were localized and no disorder of the H atoms was detected. Both structures described in the space group P121/n1 exhibit a reproducible ferroelastic switching. The hypothetical prototypic phase is orthorhombic with the space group number 60 P2/b21/n21/a. All atoms except two hydrogen species exist in pairs linked by the lost symmetry operations derived from the prototypic space group and are brought close to each other – up to 0.25 Å – under the action of them. Each of these two different H atoms is involved in an asymmetric hydrogen bond between an oxygen pair. Under the action of a lost symmetry operation each of these H atoms is displaced from one oxygen towards the other. Therefore, it is assumed that during the ferroelastic switching the jumps of these two hydrogen species take place between the pertinent hydrogen-bond acceptor and donor O atoms. Hence, these O atoms reverse their role as hydrogen-bond donors and acceptors during the ferroelastic switching.

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