Direct Visualization of Surface Structure and Charge States of Ceria-Supported Gold Catalysts Under Redox Conditions.

Observing the surface structure and charge dynamics of catalysts during catalytic reactions is crucial for elucidating reaction mechanisms. However, nanoscale characterization of the catalyst structure and charge states in the presence of reactive gases presents experimental challenges. Here, the structures and charge states of a gold nanoparticle (NP) are directly visualized on ceria during redox cycles using electron holography, a method related to transmission electron microscopy.

Noise reduction of low-dose electron holograms using the wavelet hidden Markov model.

The precision in electron holography studies on electrostatic and magnetic fields depends on the image quality of an electron hologram. Enhancing the image quality of electron holograms is essential for the comprehensive analysis of weak electromagnetic fields; however, extended electron beam irradiation can lead to undesirable radiation damage and contamination. Recent studies have demonstrated that noise reduction using the wavelet hidden Markov model (WHMM) can improve the precision of phase analysis for limited thin-foiled crystals.

Noise reduction of electron holography observations for a thin-foiled Nd-Fe-B specimen using the wavelet hidden Markov model.

In this study, we investigate the effectiveness of noise reduction in electron holography, based on the wavelet hidden Markov model (WHMM), which allows the reasonable separation of weak signals from noise. Electron holography observations from a NdFeB thin foil showed that the noise reduction method suppressed artificial phase discontinuities generated by phase retrieval. From the peak signal-to-noise ratio, it was seen that the impact of denoising was significant for observations with a narrow spacing of interference fringes, which is a key parameter for the spatial resolution of electron holography.

High-precision charge analysis in a catalytic nanoparticle by electron holography.

The charge state of supported metal catalysts is the key to understand the elementary processes involved in catalytic reactions. However, high-precision charge analysis of the metal catalysts at the atomic level is experimentally challenging. To address this critical challenge, high-sensitivity electron holography has recently been successfully applied for precisely measuring the elementary charges on individual platinum nanoparticles supported on a titanium dioxide surface.

Direct identification of the charge state in a single platinum nanoparticle on titanium oxide.

A goal in the characterization of supported metal catalysts is to achieve particle-by-particle analysis of the charge state strongly correlated with the catalytic activity. Here, we demonstrate the direct identification of the charge state of individual platinum nanoparticles (NPs) supported on titanium dioxide using ultrahigh sensitivity and precision electron holography. Sophisticated phase-shift analysis for the part of the NPs protruding into the vacuum visualized slight potential changes around individual platinum NPs.

Accuracy improvement of phase estimation in electron holography using noise reduction methods.

We try to improve the limit of the phase estimation of the interference fringe at low electron dose levels in electron holography by a noise reduction method. In this paper, we focus on unsupervised approaches to apply it to electron beam-sensitive and unknown samples and describe an overview of denoising methods used widely in image processing, such as wiener filter, total variation denoising, nonlocal mean filters and wavelet thresholding. We compare the wavelet hidden Markov model (WHMM) denoising that we have studied so far with the other conventional noise reduction methods.

Visual Target Strategies in Infantile Nystagmus Patients With Horizontal Jerk Waveform.

The aim of this study was to propose a new pathophysiological hypothesis for involuntary eye oscillation in infantile nystagmus (IN): patients with IN exhibit impaired gaze fixation, horizontal smooth pursuit and optokinetic nystagmus (OKN) and use saccadic eye movements for these underlying impairments. In order to induce saccades, they make enough angle between gaze and target by precedent exponential slow eye movements. IN consists of the alternate appearance of the saccade and the slow eye movements.

THz emission characteristics from p/n junctions with metal lines under non-bias conditions for LSI failure analysis.

We have investigated the characteristics of THz emissions from p/n junctions with metallic lines under non-bias conditions. The waveforms, spectra, and polarizations depend on the length and shape of the lines. This indicates that the transient photocurrents from p/n junctions flow into the metallic lines that emit THz waves and act as an antenna.

3D analysis of benign positional nystagmus due to cupulolithiasis in posterior semicircular canal.

Conclusions: The characteristic of both the vertical-torsional positional nystagmus with long time constant and its disappearance at the neutral head position could diagnose cupulolithiasis in posterior semicircular canal (PSCC) in the eight patients with the PSCC type of benign paroxysmal positional vertigo (P-BPPV).

Objective: The aim of the study was to diagnose cupulolithiasis in patients with P-BPPV.

Patients And Methods: We used three-dimensional rotation axis analysis of nystagmus of the vertical-torsional positional nystagmus in 111 patients with P-BPPV and evaluated its time constant.