PyHI : a GUI program for finding symmetry of helical assembly through Fourier‐Bessel indexing of electron microscopic data

2021 ◽  
Author(s):  
Xuewu Zhang
Keyword(s):  
Electron Microscopic ◽  
Electron Microscopic Data

Clay particle sizing by electrically-induced birefringence

Clay Minerals ◽  
1982 ◽  
Vol 17 (3) ◽  
pp. 313-325 ◽  
Author(s):  
D. M. Oakley ◽  
B. R. Jennings
Keyword(s):  
Orientational Order ◽  
Decay Rates ◽  
Sufficient Information ◽  
Electron Microscopic ◽  
Experimental Conditions ◽  
Clay Particles ◽  
Electron Microscopic Data ◽  
Rate Of Decay ◽  
Geometry Measurement ◽  
Log Normal

AbstractUnder the influence of a pulsed field, dilute clay sols become birefringent as the particles undergo orientational order. The rate of decay of the birefringence on removal of the field is characteristic of the particle geometry. Measurement of the decay rates under two specific experimental conditions provides sufficient information from which the particle-size distribution can be evaluated in terms of a two-parameter function. Experimental data are reported and analysed in terms of a log-normal distribution of particle sizes for attapulgite (rods), kaolinite (discs) and halloysite (ellipsoids) sols and compared with success to electron microscopic data. The ability of the method to determine size distributions in terms of the major dimensions of the clay particles, rather than those of the often used equivalent sphere, is highlighted.

The Influences of Aqueous Dispersion Media on the Cytotoxic Effect of Zinc Oxide Nanoparticles

2020 ◽  
Vol 19 (05) ◽  
pp. 2050001
Author(s):  
Kim San Tang ◽  
Jey Sern Tan
Keyword(s):  
Zinc Oxide ◽  
Zinc Oxide Nanoparticles ◽  
Physical Property ◽  
Aqueous Dispersion ◽  
Particle Dispersion ◽  
Oxide Nanoparticles ◽  
Zno Nps ◽  
Electron Microscopic ◽  
Electron Microscopic Data ◽  
Dispersion Media

Zinc oxide nanoparticles (ZnO-NPs) are widely utilized in many applications due to distinct physical and chemical characteristics. There are growing concerns that abundant use of ZnO-NPs can cause harm to humans and the environment. There is a substantial problem with reproducibility in nanotoxicology research due to the inherent properties of nanoparticles. Dispersion media are used for the preparation of nanoparticles. However, the physical and biological behaviors of ZnO-NPs in aqueous dispersion media are poorly understood. In this study, we investigated the effect of ZnO-NPs on the viability of SH-SY5Y cells. Our results showed that ZnO-NPs diluted from water-dispersed stock solution caused significant cell death at a much lower dose compared to their counterpart diluted from the phosphate-buffered saline (PBS)-dispersed stock solution. Electron microscopic data indicated that ZnO-NPs from the PBS-dispersed stock solution form much larger agglomerates compared to the one from the water-dispersed stock solution. From these data, we can conclude that the types of media used for particle dispersion impact the change in the physical property and cytotoxicity of ZnO-NPs.

scholarly journals Mapping of Homologous Interaction Sites in the Hepatitis B Virus Core Protein

1998 ◽  
Vol 72 (6) ◽  
pp. 4997-5005 ◽  
Author(s):  
Sabine König ◽  
Gertrud Beterams ◽  
Michael Nassal
Keyword(s):  
Hepatitis B Virus ◽  
Hepatitis B ◽  
Main Chain ◽  
Core Protein ◽  
Detectable Effect ◽  
Electron Microscopic ◽  
Protein Variant ◽  
Interaction Sites ◽  
B Virus ◽  
Electron Microscopic Data

ABSTRACT Hepatitis B virus consists of an outer envelope and an inner capsid, or core, that wraps around the small genome plus the viral replication enzyme. The icosahedrally symmetric nucleocapsid is assembled from multiple dimeric subunits of a single 183-residue capsid protein, which must therefore contain interfaces for monomer dimerization and for dimer multimerization. The atomic structure of the protein is not known, but electron microscopy-based image reconstructions suggested a hammerhead shape for the dimer and, very recently, led to a tentative model for the main chain trace. Here we used a combination of interaction screening techniques and functional analyses of core protein variants to define, at the primary sequence level, the regions that mediate capsid assembly. Both the two-hybrid system and the pepscan technique identified a strongly interacting region I between amino acids (aa) 78 and 117 that probably forms part of the dimer interface. Surprisingly, mutations in this region, in the context of a C-terminally truncated but assembly-competent core protein variant, had no detectable effect on assembly. By contrast, mutations in a second region, bordered by aa 113 and 143, markedly influenced capsid stability, strongly suggesting that this region II is the main contributor to dimer multimerization. Based on the electron microscopic data, it must therefore be located at the basal tips of the dimer, experimentally supporting the proposed main chain trace.

scholarly journals Structure of C protein purified from cardiac muscle.

1985 ◽  
Vol 100 (1) ◽  
pp. 208-215 ◽  
Author(s):  
H C Hartzell ◽  
W S Sale
Keyword(s):  
Cardiac Muscle ◽  
Gel Filtration ◽  
Thick Filament ◽  
Protein Molecule ◽  
Striated Muscles ◽  
Electron Microscopic ◽  
C Protein ◽  
Chicken Heart ◽  
Structural Support ◽  
Electron Microscopic Data

C protein is a component of the thick filament of striated muscles. Although the function of C protein remains unknown, a variety of evidence suggests that C protein may regulate actin-myosin interaction or be involved in structural support or elasticity of the sarcomere. We have previously proposed (Hartzell, H. C., 1984, J. Gen. Physiol., 83:563-588) that C protein is involved in regulating twitch relaxation in cardiac muscle. To gain further insight into the function of C protein, we have studied the structure of C protein purified from chicken heart. C protein was purified from extracts of detergent-washed myofibrils by sequential hydroxylapatite and DEAE-Sephacel chromatography. C protein was judged greater than 95% pure by SDS PAGE. The polypeptide subunit had a molecular weight of 155,000 and the native molecule sedimented on linear sucrose or glycerol gradients at 4-5S. For electron microscopy, purified C protein was dialyzed and diluted into a volatile buffer in 50% glycerol, aspirated onto mica, dried under vacuum, and rotary platinum-shadowed. Replicas revealed particles of relatively homogeneous overall dimensions. Over half of the particles were V-shaped. The "arm" lengths of the V-shaped particles were 22 +/- 4.5 nm (SD). Gel filtration on Sephacryl S-300 demonstrated that purified C protein had a Stokes' radius of 5.07 nm. Measurements of viscosity gave an intrinsic viscosity of 16.5 cm3/g. These data are consistent with the electron microscopic data and suggest that C protein in heart muscle is asymmetric. The C protein molecule is large enough to extend from the surface of a thick filament to adjacent thin or thick filaments.

Clay mineral mixtures as alteration products in pillow basalts from the eastern flank of Juan de Fuca Ridge: a TEM-AEM study

Clay Minerals ◽  
2001 ◽  
Vol 36 (1) ◽  
pp. 75-91 ◽  
Author(s):  
G. Giorgetti ◽  
P. Marescotti ◽  
R. Cabella ◽  
G. Lucchetti
Keyword(s):  
Electron Microscope ◽  
Juan De Fuca Ridge ◽  
Degree Of Crystallinity ◽  
Electron Microscopic ◽  
Fuca Ridge ◽  
Altered Sample ◽  
Transmission Electron ◽  
Juan De Fuca ◽  
Electron Microscopic Data ◽  
Fe Oxyhydroxides

AbstractTransmission electron microscope-analytical electron microscope analyses have been carried out on secondary minerals from pillow basalts with various degrees of alteration from the Juan de Fuca Ridge (ODP Leg 168). The electron microscopic data indicate that the alteration products consist mainly of phyllosilicate mixtures. The least altered sample shows poorly crystalline phyllosilicates occurrring as flakes with 10 Å -spaced lattice fringes. They have compositions of celadonite mixed with smectite and/or Fe oxyhydroxides and Mg-rich smectite. Proceeding towards older, more altered basalts, the alteration products consist of: (1) poorly crystalline celadonite mixtures and Mg-rich smectite; and (2) phyllosilicates with a higher degree of crystallinity, showing lattice fringes with 9.1 Å -spacing and with a talc-like composition. Changes in phyllosilicate association occur as the type of alteration changes from an oxidizing, water-dominated system (occurrence of celadonite mixtures with Fe hydroxides) to a reducing, rock-dominated system (occurrence of Fe-smectite and talc-like mixtures).

scholarly journals Comparison of Nitrogen Adsorption and Mercury Penetration Results. Pore Size Distributions for a Series of Mo-A12O3 Catalysis with Increasing MoO3 Content

1987 ◽  
Vol 4 (1-2) ◽  
pp. 87-104 ◽  
Author(s):  
Bruce D Adkins ◽  
Jill B. Heink ◽  
Burtron H. Davis
Keyword(s):  
Pore Size ◽  
Surface Area ◽  
Three Dimensional ◽  
Nitrogen Adsorption ◽  
Bet Surface Area ◽  
Size Distributions ◽  
Electron Microscopic ◽  
Pore Size Distributions ◽  
Electron Microscopic Data ◽  
Penetration Data

Scanning electron microscopic data, X-ray diffraction patterns and porosity measurements are consistent with a structure for an Mo-A12O3 catalyst series containing a single surface layer of Mo up to the point where the Mo loadings exceed the amount required for a monolayer. For greater Mo loadings than required for a monolayer, three dimensional orthorhombic MoO3 is also present. The cumulative pore volume, on an alumina basis, does not appear to be significantly altered by MoO3 loadings up to about 15 wt.%. The BET surface area, on an alumina basis, remains constant with Mo loading. However, the apparent surface area calculated from mercury penetration data decreases with Mo loading. For these materials with cylindrical pores, the Broekhoff-deBoer model for the calculation of pore size distributions produced closer agreement to the mercury penetration pore size distribution. This is in contrast to materials composed of nonporous spheres where the Broekhoff-deBoer model provided poorer agreement to mercury penetration results than either the Cohan or a packed sphere model. The results show that, within a factor of two the pore size distributions calculated from nitrogen adsorption and mercury penetration data are comparable.

Inheritance of Intracellular Bacteroids in Periplaneta Americana

1973 ◽  
Vol 31 ◽  
pp. 510-511
Author(s):  
R. S. Daniel
Keyword(s):  
Periplaneta Americana ◽  
Uranyl Acetate ◽  
Follicle Cells ◽  
Serial Sections ◽  
Intercellular Spaces ◽  
Electron Microscopic ◽  
Electron Microscopic Data ◽  
Zone Ii ◽  
Germinal Tissue ◽  
Subsequent Literature

Blockmann was the first to assume that intracellular symbiotic bacteroids of blattids are transmitted to progeny through the ovaries of the parent. Subsequent literature has generally supported the transovariole transmission theory, but whether bacteroids infect differentiated oocytes or ovarian anlage has not been determined. This paper presents electron microscopic data relevant to the question of bacteroid inheritance.Ovaries of P. americana were fixed in cacodylate buffered glutaraldehyde and osmium then block-stained in uranyl acetate. Sections were stained with uranyl acetate and lead citrate. Serial sections (Fig 1 insert) of germaria (Zone II) reveal that bacteroids are absent in formative follicle cells (Fig 1), oogonia (Fig 2) and intercellular spaces of germinal tissue in adults and nymphs.

Fast dynamic nonparametric distribution tracking in electron microscopic data

2019 ◽  
Vol 13 (3) ◽  
pp. 1537-1563 ◽  
Author(s):  
Yanjun Qian ◽  
Jianhua Z. Huang ◽  
Chiwoo Park ◽  
Yu Ding
Keyword(s):  
Electron Microscopic ◽  
Nonparametric Distribution ◽  
Electron Microscopic Data ◽  
Fast Dynamic

New Electron Microscopic Data on the Structure of the Nucleoid and Their Functional Consequences

1986 ◽  
pp. 64-81 ◽  
Author(s):  
M. A. Bjornsti ◽  
J. A. Hobot ◽  
A. S. Kelus ◽  
W. Villiger ◽  
E. Kellenberger
Keyword(s):  
Electron Microscopic ◽  
Electron Microscopic Data ◽  
Functional Consequences
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