0-kV diffractive imaging using newly developed electron diffraction microscope

a b s t r a c t A new electron diffraction microscope based on a conventional scanning electron microscope (SEM), for obtaining atomic-level resolution images without causing serious damage to the specimen, has been developed. This microscope in the relatively low-voltage region makes it possible to observe specimens at suitable resolution and record diffraction patterns. Using the microscope we accomplished 10-kV diffractive imaging with the iterative phase retrieval and reconstructed the structure of a multi-wall carbon nanotube with its finest feature corresponding to 0.34-nm carbon wall spacing. These results demonstrate the possibility of seamless connection between observing specimens by SEM and obtaining their images at high resolution by diffractive imaging

Maximum entropy method for diffractive imaging

Based on the minimization of the Lagrange formula, which is composed of two kinds of information measure, the maximum entropy method (MEM) is derived for diffractive imaging contaminated by quantum noise. This gives a suitable object corresponding to the maximum entropy principle with an iterative procedure. The MEM-based iterative phase retrieval algorithm with the initial process of the hybrid input–output (HIO-MEM) is presented, and a simple numerical example shows that the algorithm is effective for Poisson noise added to Fourier intensity. The relationship between the newly derived MEM for diffractive imaging and the conventional MEM for structure analysis based on crystallography is revealed

低エネルギー電子回折イメージング

Unlike conventional crystallography techniques, diffractive imaging becomes possible to analyze the specimen structure of non-crystalline materials. Combined low-energy electron beam with diffractive imaging, low-damage imaging technique has been developed for the analysis of light element material that is susceptible to damage due to beam. Here, it is described with respect to results of verification of low-energy electron diffractive imaging and atomic resolution imaging with carbon nanotubes as specimens. Furthermore, features of electron diffractive imaging in comparison with X-ray and our approach and efforts to date are described in this article

Generalized phase retrieval algorithm based on information measures

An iterative phase retrieval algorithm based on the maximum entropy method (MEM) is presented. Introducing a new generalized information measure, we derive a novel class of algorithms which includes the conventionally used error reduction algorithm and a MEM-type iterative algorithm which is presented for the first time. These different phase retrieval methods are unified on the basis of the framework of information measures used in information theory

Anomaly of fractal dimensions observed in stochastically switched systems

We studied an anomaly in fractal dimensions measured from the attractors of dynamical systems driven by stochastically switched inputs. We calculated the dimensions for different switching time lengths in twodimensional linear dynamical systems, and found that changes in the dimensions due to the switching time length had a singular point when the system matrix had two different real eigenvalues. Using partial dimensions along each eigenvector, we explicitly derived a generalized dimension Dq and a multifractal spectrum f to explain this anomalous property. The results from numerical calculations agreed well with those from analytical equations. We found that this anomaly is caused by linear independence, inhomogeneity of eigenvalues, and overlapping conditions. The mechanism for the anomaly could be identified for various inhomogeneous systems including nonlinear ones, and this reminded us of anomalies in some physical values observed in critical phenomena

Trehalose solution viscosity at low temperatures measured by dynamic light scattering method : Trehalose depresses molecular transportation for ice crystal growth

The inhibitory effects of trehalose on ice crystal growth were discussed on the basis of the viscosity measurements of aqueous solutions via the dynamic light-scattering method. The temperature and concentration conditions of the solution were ranged between 268 and 343K and up to 50wt%, respectively, which were feasible for applying this novel technique and were useful in the indirect measurement of the macroscopic dynamic properties of the trehalose solutions. A comparison of the viscosity data with those reported in the literatures indicated the validity of this method for measuring the viscosity. The nonlinearity of the temperature and concentration dependences of the trehalose solutions suggested that two different hydrogen-bonding networks exist in the solutions within the investigated range. Dilute solutions of less than 10wt% of trehalose exhibited properties very similar to those of pure water. Higher concentration solutions had large viscosities with large temperature and concentration dependences. This was caused by the decrease in the free water in the solution and the development of hydrogen-bonding networks with hydrated trehalose clusters. Sucrose and maltose solutions had the same properties, so this would be the dominant inhibitory process of disaccharides on ice crystal growth

Measurement of saturation processes in glutamatergic and GABAergic synapse densities during long-term development of cultured rat cortical networks

The aim of this study was to clarify the saturation processes of excitatory and inhibitory synapse densities during the long-term development of cultured neuronal networks. For this purpose, we performed a long-term culture of rat cortical cells for 35 days in vitro (DIV). During this culture period, we labeled glutamatergic and GABAergic synapses separately using antibodies against vesicular glutamate transporter 1 (VGluT1) and vesicular transporter of gamma-aminobutyric acid (VGAT). The densities and distributions of both types of synaptic terminals were measured simultaneously. Observations and subsequent measurements of immunofluorescence demonstrated that the densities of both types of antibody-labeled terminals increased gradually from 7 to 21-28 DIV. The densities did not show a further increase at 35 DIV and tended to become saturated. Triple staining with VGluT1, VGAT, and microtubule-associated protein 2 (MAP2) enabled analysis of the distribution of both types of synapses, and revealed that the densities of the two types of synaptic terminals on somata were not significantly different but that glutamatergic synapses predominated on the dendrites during long-term culture. However, some neurons did not fall within this distribution, suggesting differences in synapse distribution on target neurons. The electrical activity also showed an initial increase and subsequent saturation of the firing rate and synchronized burst rate during long-term culture, and the number of days of culture to saturation from the initial increase followed the same pattern under this culture condition. (C) 2013 Elsevier B.V. All rights reserved

Temporal and spatial variations of lipid droplets during adipocyte division and differentiation

By capturing time-lapse images of primary stromal-vascular cells (SVCs) derived from rat mesenteric adipose tissue, we revealed temporal and spatial variations of lipid droplets (LDs) in individual SVCs during adipocyte differentiation. Numerous small LDs (a few micrometers in diameter) appeared in the perinuclear region at an early stage of differentiation; subsequently, several LDs grew to more than 10 µm in diameter and occupied the cytoplasm. We have developed a method for the fluorescence staining of LDs in living adipocytes. Time-lapse observation of the stained cells at higher magnification showed that nascent LDs (several 100 nm in diameter) grew into small LDs while moving from lamellipodia to the perinuclear region. We also found that adipocytes are capable of division and that they evenly distribute the LDs between two daughter cells. Immunofluorescence observations of LD-associated proteins revealed that such cell divisions of SVCs occurred even after LDs were coated with perilipin, suggesting that the "final" cell division during adipocyte differentiation occurs considerably later than that characterized in 3T3-L1 cells. Our time-lapse observations have provided a detailed account of the morphological changes that SVCs undergo during adipocyte division and differentiation

Spherical shell structure of distribution of images reconstructed by diffractive imaging

Image reconstruction from Fourier intensity through phase retrieval was investigated when the intensity was contaminated with Poisson noise. Although different initial conditions and/or the instability of the iterative phase retrieval process led to different reconstructed images, we found that the distribution of the resulting images in both the object and Fourier spaces formed spherical shell structures. Averaging of the images over the distribution corresponds to the position of the image at the sphere center