scholarly journals Dark field nanoparticle tracking analysis for size characterization of plasmonic and non-plasmonic particles

2014 ◽  
Vol 16 (5) ◽  
Author(s):  
Thorsten Wagner ◽  
Hans-Gerd Lipinski ◽  
Martin Wiemann
Keyword(s):  
Dark Field ◽  
Nanoparticle Tracking Analysis ◽  
Size Characterization ◽  
Plasmonic Particles

Dark field imaging system for size characterization of magnetic micromarkers

2017 ◽  
Author(s):  
A. Malec ◽  
C. Haiden ◽  
G. Kokkinis ◽  
F. Keplinger ◽  
I. Giouroudi
Keyword(s):  
Imaging System ◽  
Dark Field ◽  
Dark Field Imaging ◽  
Size Characterization ◽  
Field Imaging

Characterization of frozen hydrated biological specimens by low-loss EELS

1992 ◽  
Vol 50 (2) ◽  
pp. 1572-1573
Author(s):  
Songquan Sun ◽  
Richard D. Leapman
Keyword(s):  
Water Content ◽  
Direct Method ◽  
Internal Standard ◽  
Dry Weight ◽  
Dark Field ◽  
Protein Solutions ◽  
Subcellular Compartment ◽  
Differential Shrinkage ◽  
Electron Energy Loss

Analyses of ultrathin cryosections are generally performed after freeze-drying because the presence of water renders the specimens highly susceptible to radiation damage. The water content of a subcellular compartment is an important quantity that must be known, for example, to convert the dry weight concentrations of ions to the physiologically more relevant molar concentrations. Water content can be determined indirectly from dark-field mass measurements provided that there is no differential shrinkage between compartments and that there exists a suitable internal standard. The potential advantage of a more direct method for measuring water has led us to explore the use of electron energy loss spectroscopy (EELS) for characterizing biological specimens in their frozen hydrated state.We have obtained preliminary EELS measurements from pure amorphous ice and from cryosectioned frozen protein solutions. The specimens were cryotransfered into a VG-HB501 field-emission STEM equipped with a 666 Gatan parallel-detection spectrometer and analyzed at approximately −160 C.

The development of body and organ shape

BMC Zoology ◽  
2020 ◽  
Vol 5 (1) ◽  
Author(s):  
Ansa E. Cobham ◽  
Christen K. Mirth
Keyword(s):  
Relative Position ◽  
Body Shape ◽  
Single Cells ◽  
The Other ◽  
Geometric Features ◽  
Main Text ◽  
Size Characterization ◽  
Organ Shape ◽  
The Many

Abstract Background Organisms show an incredibly diverse array of body and organ shapes that are both unique to their taxon and important for adapting to their environment. Achieving these specific shapes involves coordinating the many processes that transform single cells into complex organs, and regulating their growth so that they can function within a fully-formed body. Main text Conceptually, body and organ shape can be separated in two categories, although in practice these categories need not be mutually exclusive. Body shape results from the extent to which organs, or parts of organs, grow relative to each other. The patterns of relative organ size are characterized using allometry. Organ shape, on the other hand, is defined as the geometric features of an organ’s component parts excluding its size. Characterization of organ shape is frequently described by the relative position of homologous features, known as landmarks, distributed throughout the organ. These descriptions fall into the domain of geometric morphometrics. Conclusion In this review, we discuss the methods of characterizing body and organ shape, the developmental programs thought to underlie each, highlight when and how the mechanisms regulating body and organ shape might overlap, and provide our perspective on future avenues of research.

Intergrowth of niobium tungsten oxides of the tetragonal tungsten bronze type

2020 ◽  
Vol 75 (11) ◽  
pp. 913-919
Author(s):  
Frank Krumeich
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Tungsten Bronze ◽  
Structural Complexity ◽  
Dark Field ◽  
Tetragonal Tungsten Bronze ◽  
Tungsten Oxides ◽  
Transmission Electron ◽  
Scanning Transmission

AbstractSince the 1970s, high-resolution transmission electron microscopy (HRTEM) is well established as the most appropriate method to explore the structural complexity of niobium tungsten oxides. Today, scanning transmission electron microscopy (STEM) represents an important alternative for performing the structural characterization of such oxides. STEM images recorded with a high-angle annular dark field (HAADF) detector provide not only information about the cation positions but also about the distribution of niobium and tungsten as the intensity is directly correlated to the local scattering potential. The applicability of this method is demonstrated here for the characterization of the real structure of Nb7W10O47.5. This sample contains well-ordered domains of Nb8W9O47 and Nb4W7O31 besides little ordered areas according to HRTEM results. Structural models for Nb4W7O31 and twinning occurring in this phase have been derived from the interpretation of HAADF-STEM images. A remarkable grain boundary between well-ordered domains of Nb4W7O31 and Nb8W9O47 has been found that contains one-dimensionally periodic features. Furthermore, short-range order observed in less ordered areas could be attributed to an intimate intergrowth of small sections of different tetragonal tungsten bronze (TTB) based structures.

scholarly journals Deep Learning Based Instance Segmentation of Titanium Dioxide Particles in the Form of Agglomerates in Scanning Electron Microscopy

Nanomaterials ◽  
2021 ◽  
Vol 11 (4) ◽  
pp. 968
Author(s):  
Paul Monchot ◽  
Loïc Coquelin ◽  
Khaled Guerroudj ◽  
Nicolas Feltin ◽  
Alexandra Delvallée ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Titanium Dioxide ◽  
Learning Community ◽  
Spherical Particles ◽  
Average Value ◽  
Size Characterization ◽  
Scanning Electron

The size characterization of particles present in the form of agglomerates in images measured by scanning electron microscopy (SEM) requires a powerful image segmentation tool in order to properly define the boundaries of each particle. In this work, we propose to use an algorithm from the deep statistical learning community, the Mask-RCNN, coupled with transfer learning to overcome the problem of generalization of the commonly used image processing methods such as watershed or active contour. Indeed, the adjustment of the parameters of these algorithms is almost systematically necessary and slows down the automation of the processing chain. The Mask-RCNN is adapted here to the case study and we present results obtained on titanium dioxide samples (non-spherical particles) with a level of performance evaluated by different metrics such as the DICE coefficient, which reaches an average value of 0.95 on the test images.

Internalization of hyaluronan by chondrocytes occurs via receptor-mediated endocytosis

1993 ◽  
Vol 106 (1) ◽  
pp. 365-375 ◽  
Author(s):  
Q. Hua ◽  
C.B. Knudson ◽  
W. Knudson
Keyword(s):  
Cell Surface ◽  
Articular Chondrocytes ◽  
Dark Field ◽  
Cartilage Tissue ◽  
Receptor Mediated Endocytosis ◽  
Dark Field Microscopy ◽  
Bovine Articular Chondrocytes ◽  
Hyaluronan Receptors ◽  
Hyaluronan Receptor

Several studies have suggested that chondrocytes must have the capacity to internalize and degrade extracellular hyaluronan. In the present study we show direct evidence that hyaluronan is, in fact, endocytosed by chondrocytes and that the endocytosis is mediated via cell surface CD44/hyaluronan receptors. Cultures of bovine articular chondrocytes as well as rat chondrosarcoma chondrocytes were incubated with either fluorescein- or 3H-labeled hyaluronan. Intense binding and accumulation of labeled hyaluronan was visualized by fluorescence microscopy or bright-field/dark-field microscopy following autoradiography. Cell surface hyaluronan was removed with either trypsin or Streptomyces hyaluronidase in order to distinguish and quantify intracellular endocytosed hyaluronan. Labeled hyaluronan was visualized within small discrete intracellular vesicles distributed throughout the cytoplasm. Binding and endocytosis of fluorescein- or 3H-labeled hyaluronan was totally blocked by the addition of excess unlabeled hyaluronan or hyaluronan hexasaccharides, competitive inhibitors of hyaluronan/hyaluronan receptor interactions. Binding and endocytosis was also blocked by the addition of anti-CD44 monoclonal antibodies. Characterization of endocytosed 3H-labeled hyaluronan demonstrated that a significant portion of the hyaluronan was degraded by both the bovine articular and rat chondrosarcoma chondrocytes. Interestingly, a higher proportion of bound hyaluronan was internalized by the bovine chondrocytes. Therefore, hyaluronan receptor-mediated endocytosis and degradation of hyaluronan may provide a critical link to the maintenance and homeostasis of cartilage tissue.

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