High pressure freezing and cryo-sectioning can be used for protein structure determination by electron diffraction
Ultramicroscopy. 2023 Aug 25;254:113834. doi: 10.1016/j.ultramic.2023.113834. Online ahead of print.ABSTRACTElectron diffraction of three-dimensional nanometer sized crystals has emerged since 2013 as an efficient technique to solve the structure of both small organic molecules and model proteins. However, the major bottleneck of the technique when applied to protein samples is to produce nano-crystals that do not exceed 200 to 300 nm in at least one dimension and to deposit them on a grid while keeping the minimum amount of solvent around them. Since the presence of amorphous solvent around the crystal, necessary to prese...
Source: Ultramicroscopy - September 4, 2023 Category: Laboratory Medicine Authors: Christine Moriscot Guy Schoehn Dominique Housset Source Type: research
Scanning capacitance microscopy of GaN-based high electron mobility transistor structures: A practical guide
Ultramicroscopy. 2023 Aug 22;254:113833. doi: 10.1016/j.ultramic.2023.113833. Online ahead of print.ABSTRACTThe scanning capacitance microscope (SCM) is a powerful tool to characterise local electrical properties in GaN-based high electron mobility transistor (HEMT) structures with nanoscale resolution. We investigated the experimental setup and the imaging conditions to optimise the SCM contrast. As to the experimental setup, we show that the desired tip should be sharp (e.g., with the tip radius of ≤25nm) and its coating should be made of conductive doped diamond. Most importantly, its spring constant should be large t...
Source: Ultramicroscopy - September 4, 2023 Category: Laboratory Medicine Authors: Chen Chen Saptarsi Ghosh Francesca Adams Menno J Kappers David J Wallis Rachel A Oliver Source Type: research
High pressure freezing and cryo-sectioning can be used for protein structure determination by electron diffraction
Ultramicroscopy. 2023 Aug 25;254:113834. doi: 10.1016/j.ultramic.2023.113834. Online ahead of print.ABSTRACTElectron diffraction of three-dimensional nanometer sized crystals has emerged since 2013 as an efficient technique to solve the structure of both small organic molecules and model proteins. However, the major bottleneck of the technique when applied to protein samples is to produce nano-crystals that do not exceed 200 to 300 nm in at least one dimension and to deposit them on a grid while keeping the minimum amount of solvent around them. Since the presence of amorphous solvent around the crystal, necessary to prese...
Source: Ultramicroscopy - September 4, 2023 Category: Laboratory Medicine Authors: Christine Moriscot Guy Schoehn Dominique Housset Source Type: research
Scanning capacitance microscopy of GaN-based high electron mobility transistor structures: A practical guide
Ultramicroscopy. 2023 Aug 22;254:113833. doi: 10.1016/j.ultramic.2023.113833. Online ahead of print.ABSTRACTThe scanning capacitance microscope (SCM) is a powerful tool to characterise local electrical properties in GaN-based high electron mobility transistor (HEMT) structures with nanoscale resolution. We investigated the experimental setup and the imaging conditions to optimise the SCM contrast. As to the experimental setup, we show that the desired tip should be sharp (e.g., with the tip radius of ≤25nm) and its coating should be made of conductive doped diamond. Most importantly, its spring constant should be large t...
Source: Ultramicroscopy - September 4, 2023 Category: Laboratory Medicine Authors: Chen Chen Saptarsi Ghosh Francesca Adams Menno J Kappers David J Wallis Rachel A Oliver Source Type: research
High pressure freezing and cryo-sectioning can be used for protein structure determination by electron diffraction
Ultramicroscopy. 2023 Aug 25;254:113834. doi: 10.1016/j.ultramic.2023.113834. Online ahead of print.ABSTRACTElectron diffraction of three-dimensional nanometer sized crystals has emerged since 2013 as an efficient technique to solve the structure of both small organic molecules and model proteins. However, the major bottleneck of the technique when applied to protein samples is to produce nano-crystals that do not exceed 200 to 300 nm in at least one dimension and to deposit them on a grid while keeping the minimum amount of solvent around them. Since the presence of amorphous solvent around the crystal, necessary to prese...
Source: Ultramicroscopy - September 4, 2023 Category: Laboratory Medicine Authors: Christine Moriscot Guy Schoehn Dominique Housset Source Type: research
Scanning capacitance microscopy of GaN-based high electron mobility transistor structures: A practical guide
Ultramicroscopy. 2023 Aug 22;254:113833. doi: 10.1016/j.ultramic.2023.113833. Online ahead of print.ABSTRACTThe scanning capacitance microscope (SCM) is a powerful tool to characterise local electrical properties in GaN-based high electron mobility transistor (HEMT) structures with nanoscale resolution. We investigated the experimental setup and the imaging conditions to optimise the SCM contrast. As to the experimental setup, we show that the desired tip should be sharp (e.g., with the tip radius of ≤25nm) and its coating should be made of conductive doped diamond. Most importantly, its spring constant should be large t...
Source: Ultramicroscopy - September 4, 2023 Category: Laboratory Medicine Authors: Chen Chen Saptarsi Ghosh Francesca Adams Menno J Kappers David J Wallis Rachel A Oliver Source Type: research
High pressure freezing and cryo-sectioning can be used for protein structure determination by electron diffraction
Ultramicroscopy. 2023 Aug 25;254:113834. doi: 10.1016/j.ultramic.2023.113834. Online ahead of print.ABSTRACTElectron diffraction of three-dimensional nanometer sized crystals has emerged since 2013 as an efficient technique to solve the structure of both small organic molecules and model proteins. However, the major bottleneck of the technique when applied to protein samples is to produce nano-crystals that do not exceed 200 to 300 nm in at least one dimension and to deposit them on a grid while keeping the minimum amount of solvent around them. Since the presence of amorphous solvent around the crystal, necessary to prese...
Source: Ultramicroscopy - September 4, 2023 Category: Laboratory Medicine Authors: Christine Moriscot Guy Schoehn Dominique Housset Source Type: research
Reliable phase quantification in focused probe electron ptychography of thin materials
Ultramicroscopy. 2023 Aug 18;254:113829. doi: 10.1016/j.ultramic.2023.113829. Online ahead of print.ABSTRACTElectron ptychography provides highly sensitive, dose efficient phase images which can be corrected for aberrations after the data has been acquired. This is crucial when very precise quantification is required, such as with sensitivity to charge transfer due to bonding. Drift can now be essentially eliminated as a major impediment to focused probe ptychography, which benefits from the availability of easily interpretable simultaneous Z-contrast imaging. However challenges have remained when quantifying the ptychogra...
Source: Ultramicroscopy - August 26, 2023 Category: Laboratory Medicine Authors: Christoph Hofer Timothy J Pennycook Source Type: research
Convexity constraints on linear background models for electron energy-loss spectra
Ultramicroscopy. 2023 Aug 14;254:113830. doi: 10.1016/j.ultramic.2023.113830. Online ahead of print.ABSTRACTIn this paper convexity constraints are derived for a background model of electron energy loss spectra (EELS) that is linear in the fitting parameters. The model outperforms a power-law both on experimental and simulated backgrounds, especially for wide energy ranges, and thus improves elemental quantification results. Owing to the model's linearity, the constraints can be imposed through fitting by quadratic programming. This has important advantages over conventional nonlinear power-law fitting such as high speed a...
Source: Ultramicroscopy - August 26, 2023 Category: Laboratory Medicine Authors: Wouter Van den Broek Daen Jannis Jo Verbeeck Source Type: research
Reliable phase quantification in focused probe electron ptychography of thin materials
Ultramicroscopy. 2023 Aug 18;254:113829. doi: 10.1016/j.ultramic.2023.113829. Online ahead of print.ABSTRACTElectron ptychography provides highly sensitive, dose efficient phase images which can be corrected for aberrations after the data has been acquired. This is crucial when very precise quantification is required, such as with sensitivity to charge transfer due to bonding. Drift can now be essentially eliminated as a major impediment to focused probe ptychography, which benefits from the availability of easily interpretable simultaneous Z-contrast imaging. However challenges have remained when quantifying the ptychogra...
Source: Ultramicroscopy - August 26, 2023 Category: Laboratory Medicine Authors: Christoph Hofer Timothy J Pennycook Source Type: research
Convexity constraints on linear background models for electron energy-loss spectra
Ultramicroscopy. 2023 Aug 14;254:113830. doi: 10.1016/j.ultramic.2023.113830. Online ahead of print.ABSTRACTIn this paper convexity constraints are derived for a background model of electron energy loss spectra (EELS) that is linear in the fitting parameters. The model outperforms a power-law both on experimental and simulated backgrounds, especially for wide energy ranges, and thus improves elemental quantification results. Owing to the model's linearity, the constraints can be imposed through fitting by quadratic programming. This has important advantages over conventional nonlinear power-law fitting such as high speed a...
Source: Ultramicroscopy - August 26, 2023 Category: Laboratory Medicine Authors: Wouter Van den Broek Daen Jannis Jo Verbeeck Source Type: research
Reliable phase quantification in focused probe electron ptychography of thin materials
Ultramicroscopy. 2023 Aug 18;254:113829. doi: 10.1016/j.ultramic.2023.113829. Online ahead of print.ABSTRACTElectron ptychography provides highly sensitive, dose efficient phase images which can be corrected for aberrations after the data has been acquired. This is crucial when very precise quantification is required, such as with sensitivity to charge transfer due to bonding. Drift can now be essentially eliminated as a major impediment to focused probe ptychography, which benefits from the availability of easily interpretable simultaneous Z-contrast imaging. However challenges have remained when quantifying the ptychogra...
Source: Ultramicroscopy - August 26, 2023 Category: Laboratory Medicine Authors: Christoph Hofer Timothy J Pennycook Source Type: research
Convexity constraints on linear background models for electron energy-loss spectra
Ultramicroscopy. 2023 Aug 14;254:113830. doi: 10.1016/j.ultramic.2023.113830. Online ahead of print.ABSTRACTIn this paper convexity constraints are derived for a background model of electron energy loss spectra (EELS) that is linear in the fitting parameters. The model outperforms a power-law both on experimental and simulated backgrounds, especially for wide energy ranges, and thus improves elemental quantification results. Owing to the model's linearity, the constraints can be imposed through fitting by quadratic programming. This has important advantages over conventional nonlinear power-law fitting such as high speed a...
Source: Ultramicroscopy - August 26, 2023 Category: Laboratory Medicine Authors: Wouter Van den Broek Daen Jannis Jo Verbeeck Source Type: research
Reliable phase quantification in focused probe electron ptychography of thin materials
Ultramicroscopy. 2023 Aug 18;254:113829. doi: 10.1016/j.ultramic.2023.113829. Online ahead of print.ABSTRACTElectron ptychography provides highly sensitive, dose efficient phase images which can be corrected for aberrations after the data has been acquired. This is crucial when very precise quantification is required, such as with sensitivity to charge transfer due to bonding. Drift can now be essentially eliminated as a major impediment to focused probe ptychography, which benefits from the availability of easily interpretable simultaneous Z-contrast imaging. However challenges have remained when quantifying the ptychogra...
Source: Ultramicroscopy - August 26, 2023 Category: Laboratory Medicine Authors: Christoph Hofer Timothy J Pennycook Source Type: research
Convexity constraints on linear background models for electron energy-loss spectra
Ultramicroscopy. 2023 Aug 14;254:113830. doi: 10.1016/j.ultramic.2023.113830. Online ahead of print.ABSTRACTIn this paper convexity constraints are derived for a background model of electron energy loss spectra (EELS) that is linear in the fitting parameters. The model outperforms a power-law both on experimental and simulated backgrounds, especially for wide energy ranges, and thus improves elemental quantification results. Owing to the model's linearity, the constraints can be imposed through fitting by quadratic programming. This has important advantages over conventional nonlinear power-law fitting such as high speed a...
Source: Ultramicroscopy - August 26, 2023 Category: Laboratory Medicine Authors: Wouter Van den Broek Daen Jannis Jo Verbeeck Source Type: research
