scholarly journals High-resolution imaging of catalytic activity of a single graphene sheet using electrochemiluminescence microscopy

2021 ◽  
Vol 12 (13) ◽  
pp. 4794-4799
Author(s):  
Hui Zhu ◽  
Dechen Jiang ◽  
Jun-Jie Zhu
Keyword(s):  
Catalytic Activity ◽  
High Resolution ◽  
Graphene Sheet ◽  
Electrocatalytic Activity ◽  
High Resolution Imaging ◽  
Nanometer Resolution ◽  
Resolution Imaging

High spatial electrochemiluminescence microscopy is established to map the electrocatalytic activity of a single graphene sheet with a nanometer resolution.

scholarly journals PKC-e Regulates Vesicle Delivery and Focal Exocytosis for Efficient IgG-mediated Phagocytosis

2021 ◽  
Author(s):  
Anna E. D'Amico ◽  
Alexander C. Wong ◽  
Cheryl M. Zajd ◽  
Xuexin Zhang ◽  
Ananya Murali ◽  
...  
Keyword(s):  
Catalytic Activity ◽  
High Resolution ◽  
Vesicular Transport ◽  
Vesicular Trafficking ◽  
High Resolution Imaging ◽  
Regulatory Domain ◽  
Resolution Imaging ◽  
Membrane Addition

PKC-e is required for membrane addition during IgG-mediated phagocytosis; its role in this process is ill-defined. High resolution imaging revealed that PKC-e exits the Golgi and enters phagosomes on vesicles that then fuse. TNF and PKC-e colocalize at the Golgi and on vesicles that enter the phagosome. Loss of PKC-e and TNF delivery upon nocodazole treatment confirmed vesicular transport on microtubules. That TNF+ vesicles are not delivered in macrophages from PKC-e null mice, or upon dissociation of the Golgi-associated pool of PKC-e, implicates Golgi-tethered PKC-e as a driver of Golgi-to-phagosome trafficking. Finally, we established that PKC-e's regulatory domain is sufficient for delivery of TNF+ vesicles to the phagosome. These studies reveal a novel role for PKC-e in focal exocytosis: its regulatory domain drives Golgi-derived vesicles to the phagosome while catalytic activity is required for their fusion. This is one of the first examples of a PKC requirement for vesicular trafficking and describes a novel function for a PKC regulatory domain.

scholarly journals PKC-ε Regulates Vesicle Delivery and Focal Exocytosis for Efficient IgG-mediated Phagocytosis

2021 ◽  
Author(s):  
Anna E D'Amico ◽  
Alexander C Wong ◽  
Cheryl M Zajd ◽  
Ananya Murali ◽  
Michelle Lennartz
Keyword(s):  
Catalytic Activity ◽  
High Resolution ◽  
Vesicular Transport ◽  
Vesicular Trafficking ◽  
High Resolution Imaging ◽  
Regulatory Domain ◽  
Tnf Α ◽  
Resolution Imaging ◽  
Membrane Addition

PKC-ε is required for membrane addition during IgG-mediated phagocytosis; its role in this process is ill-defined. High resolution imaging revealed that PKC-ε exits the Golgi and enters phagosomes on vesicles that then fuse. TNF-α and PKC-α colocalize at the Golgi and on vesicles that enter the phagosome. Loss of PKC-ε and TNF-α delivery upon nocodazole treatment confirmed vesicular transport on microtubules. That TNF-α+ vesicles are not delivered in macrophages from PKC-ε null mice, or upon dissociation of the Golgi-associated pool of PKC-ε, implicates Golgi-tethered PKC-ε as a driver of Golgi-to-phagosome trafficking. Finally, we established that PKC-ε's regulatory domain is sufficient for delivery of TNF-α+ vesicles to the phagosome. These studies reveal a novel role for PKC-ε in focal exocytosis: its regulatory domain drives Golgi-derived vesicles to the phagosome while catalytic activity is required for their fusion. This is one of the first examples of a PKC requirement for vesicular trafficking and describes a novel function for a PKC regulatory domain.

scholarly journals Holography: application to high-resolution imaging

Microscopy ◽  
2020 ◽  
Author(s):  
Takeshi Kawasaki ◽  
Yoshio Takahashi ◽  
Toshiaki Tanigaki
Keyword(s):  
High Resolution ◽  
High Precision ◽  
Functional Materials ◽  
Electron Holography ◽  
High Resolution Imaging ◽  
Nanometer Resolution ◽  
Powerful Technique ◽  
Resolution Electron ◽  
Resolution Imaging ◽  
Electron Microscopes

Abstract Electron holography was invented for correcting aberrations of the lenses of electron microscopes. It was used to observe the atomic arrangements in crystals after decades of research. Then it was combined with a hardware aberration corrector to enable high-resolution and high-precision analysis. Its applications were further extended to magnetic observations with sub-nanometer resolution. High-resolution electron holography has become a powerful technique for observing electromagnetic distributions in functional materials.

Alternative approaches to ultra-high resolution imaging

1991 ◽  
Vol 49 ◽  
pp. 650-651
Author(s):  
J.M. Cowley
Keyword(s):  
High Resolution ◽  
High Voltage ◽  
High Resolution Electron Microscopy ◽  
Crystal Defects ◽  
High Resolution Imaging ◽  
General Applicability ◽  
Resolution Electron ◽  
Radiation Resistant ◽  
Resolution Imaging ◽  
Alternative Approaches

By extrapolation of past experience, it would seem that the future of ultra-high resolution electron microscopy rests with the advances of electron optical engineering that are improving the instrumental stability of high voltage microscopes to achieve the theoretical resolutions of 1Å or better at 1MeV or higher energies. While these high voltage instruments will undoubtedly produce valuable results on chosen specimens, their general applicability has been questioned on the basis of the excessive radiation damage effects which may significantly modify the detailed structures of crystal defects within even the most radiation resistant materials in a period of a few seconds. Other considerations such as those of cost and convenience of use add to the inducement to consider seriously the possibilities for alternative approaches to the achievement of comparable resolutions.

Principle and practice of high-resolution imaging with a field-emission TEM

1992 ◽  
Vol 50 (1) ◽  
pp. 138-139
Author(s):  
Max T. Otten ◽  
Wim M.J. Coene
Keyword(s):  
High Resolution ◽  
Field Emission ◽  
Incidence Angle ◽  
Temporal Coherence ◽  
Energy Spread ◽  
High Resolution Imaging ◽  
Major Improvement ◽  
High Resolution Images ◽  
Resolution Imaging

High-resolution imaging with a LaB6 instrument is limited by the spatial and temporal coherence, with little contrast remaining beyond the point resolution. A Field Emission Gun (FEG) reduces the incidence angle by a factor 5 to 10 and the energy spread by 2 to 3. Since the incidence angle is the dominant limitation for LaB6 the FEG provides a major improvement in contrast transfer, reducing the information limit to roughly one half of the point resolution. The strong improvement, predicted from high-resolution theory, can be seen readily in diffractograms (Fig. 1) and high-resolution images (Fig. 2). Even if the information in the image is limited deliberately to the point resolution by using an objective aperture, the improved contrast transfer close to the point resolution (Fig. 1) is already worthwhile.

Imaging of ferroelectric domain walls by electron holography

1992 ◽  
Vol 50 (1) ◽  
pp. 246-247
Author(s):  
Xiao Zhang
Keyword(s):  
Magnetic Field ◽  
High Resolution ◽  
Domain Walls ◽  
Ferroelectric Domain ◽  
Object Wave ◽  
Electron Holography ◽  
High Resolution Imaging ◽  
Quantitative Measurements ◽  
Resolution Imaging ◽  
Electron Microscopes

Electron holography has recently been available to modern electron microscopy labs with the development of field emission electron microscopes. The unique advantage of recording both amplitude and phase of the object wave makes electron holography a effective tool to study electron optical phase objects. The visibility of the phase shifts of the object wave makes it possible to directly image the distributions of an electric or a magnetic field at high resolution. This work presents preliminary results of first high resolution imaging of ferroelectric domain walls by electron holography in BaTiO3 and quantitative measurements of electrostatic field distribution across domain walls.

The method of replication affects metal film granularity and resolution

1989 ◽  
Vol 47 ◽  
pp. 708-709
Author(s):  
George C. Ruben
Keyword(s):  
Electron Beam ◽  
High Resolution ◽  
Film Thickness ◽  
Single Molecule ◽  
Metal Film ◽  
Vertical Surface ◽  
High Resolution Imaging ◽  
Controllable Factors ◽  
Resolution Imaging

Single molecule resolution in electron beam sensitive, uncoated, noncrystalline materials has been impossible except in thin Pt-C replicas ≤ 150Å) which are resistant to the electron beam destruction. Previously the granularity of metal film replicas limited their resolution to ≥ 20Å. This paper demonstrates that Pt-C film granularity and resolution are a function of the method of replication and other controllable factors. Low angle 20° rotary , 45° unidirectional and vertical 9.7±1 Å Pt-C films deposited on mica under the same conditions were compared in Fig. 1. Vertical replication had a 5A granularity (Fig. 1c), the highest resolution (table), and coated the whole surface. 45° replication had a 9Å granulartiy (Fig. 1b), a slightly poorer resolution (table) and did not coat the whole surface. 20° rotary replication was unsuitable for high resolution imaging with 20-25Å granularity (Fig. 1a) and resolution 2-3 times poorer (table). Resolution is defined here as the greatest distance for which the metal coat on two opposing faces just grow together, that is, two times the apparent film thickness on a single vertical surface.

Performance Evaluation of a Novel Type of Low-Energy Electron Microscope

1990 ◽  
Vol 48 (1) ◽  
pp. 354-355
Author(s):  
Bertholdand Senftinger ◽  
Helmut Liebl
Keyword(s):  
Electron Microscope ◽  
High Resolution ◽  
Field Strength ◽  
Numerical Aperture ◽  
Low Energy ◽  
Energy Electron ◽  
High Resolution Imaging ◽  
Lens System ◽  
Resolution Imaging ◽  
Low Energy Electron

During the last few years the investigation of clean and adsorbate-covered solid surfaces as well as thin-film growth and molecular dynamics have given rise to a constant demand for high-resolution imaging microscopy with reflected and diffracted low energy electrons as well as photo-electrons. A recent successful implementation of a UHV low-energy electron microscope by Bauer and Telieps encouraged us to construct such a low energy electron microscope (LEEM) for high-resolution imaging incorporating several novel design features, which is described more detailed elsewhere.The constraint of high field strength at the surface required to keep the aberrations caused by the accelerating field small and high UV photon intensity to get an improved signal-to-noise ratio for photoemission led to the design of a tetrode emission lens system capable of also focusing the UV light at the surface through an integrated Schwarzschild-type objective. Fig. 1 shows an axial section of the emission lens in the LEEM with sample (28) and part of the sample holder (29). The integrated mirror objective (50a, 50b) is used for visual in situ microscopic observation of the sample as well as for UV illumination. The electron optical components and the sample with accelerating field followed by an einzel lens form a tetrode system. In order to keep the field strength high, the sample is separated from the first element of the einzel lens by only 1.6 mm. With a numerical aperture of 0.5 for the Schwarzschild objective the orifice in the first element of the einzel lens has to be about 3.0 mm in diameter. Considering the much smaller distance to the sample one can expect intense distortions of the accelerating field in front of the sample. Because the achievable lateral resolution depends mainly on the quality of the first imaging step, careful investigation of the aberrations caused by the emission lens system had to be done in order to avoid sacrificing high lateral resolution for larger numerical aperture.

High-resolution imaging of transition metal and sulfur-redox distribution in individual microfossils

2003 ◽  
Vol 104 ◽  
pp. 381-384 ◽  
Author(s):  
P. Philippot ◽  
J. Foriel ◽  
J. Susini ◽  
H. Khodja ◽  
N. Grassineau ◽  
...  
Keyword(s):  
High Resolution ◽  
Transition Metal ◽  
High Resolution Imaging ◽  
Resolution Imaging
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