scholarly journals Enigmatic dual symbiosis in the excretory organ of Nautilus macromphalus (Cephalopoda: Nautiloidea)

2007 ◽  
Vol 274 (1614) ◽  
pp. 1143-1152 ◽  
Author(s):  
Mathieu Pernice ◽  
Silke Wetzel ◽  
Olivier Gros ◽  
Renata Boucher-Rodoni ◽  
Nicole Dubilier
Keyword(s):  
Sequence Similarity ◽  
Ammonia Oxidizing Bacteria ◽  
Living Fossil ◽  
Symbiotic Associations ◽  
Transmission Electron ◽  
Physiological Adaptations ◽  
Excretory Organ ◽  
Pericardial Villi ◽  
Insight Into

Symbiosis is an important driving force in metazoan evolution and the study of ancient lineages can provide an insight into the influence of symbiotic associations on morphological and physiological adaptations. In the ‘living fossil’ Nautilus , bacterial associations are found in the highly specialized pericardial appendage. This organ is responsible for most of the excretory processes (ultrafiltration, reabsorption and secretion) and secretes an acidic ammonia-rich excretory fluid. In this study, we show that Nautilus macromphalus pericardial appendages harbour a high density of a β-proteobacterium and a coccoid spirochaete using transmission electron microscopy, comparative 16S rRNA sequence analysis and fluorescence in situ hybridization (FISH). These two bacterial phylotypes are phylogenetically distant from any known bacteria, with ammonia-oxidizing bacteria as the closest relatives of the β-proteobacterium (above or equal to 87.5% sequence similarity) and marine Spirochaeta species as the closest relatives of the spirochaete (above or equal to 89.8% sequence similarity), and appear to be specific to Nautilus . FISH analyses showed that the symbionts occur in the baso-medial region of the pericardial villi where ultrafiltration and reabsorption processes take place, suggesting a symbiotic contribution to the excretory metabolism.

In-Situ Tem Investigation During Thermal Cycling of thin Copper Films

1996 ◽  
Vol 436 ◽  
Author(s):  
R.-M. Keller ◽  
W. Sigle ◽  
S. P. Baker ◽  
O. Kraft ◽  
E. Arzt
Keyword(s):  
Grain Growth ◽  
Room Temperature ◽  
Dislocation Motion ◽  
In Situ Tem ◽  
Copper Films ◽  
Stress Evolution ◽  
Cu Films ◽  
Transmission Electron ◽  
Insight Into

AbstractIn-situ transmission electron microscopy (TEM) was performed to study grain growth and dislocation motion during temperature cycles of Cu films with and without a cap layer. In addition, the substrate curvature method was employed to determine the corresponding stresstemperature curves from room temperature up to 600°C. The results of the in-situ TEM investigations provide insight into the microstructural evolution which occurs during the stress measurements. Grain growth occurred continuously throughout the first heating cycle in both cases. The evolution of dislocation structure observed in TEM supports an explanation of the stress evolution in both capped and uncapped films in terms of dislocation effects.

In situ liquid-cell transmission electron microscopy for direct observation of concentration-dependent growth and dissolution of silver nanoparticles

RSC Advances ◽  
2015 ◽  
Vol 5 (100) ◽  
pp. 82342-82345 ◽  
Author(s):  
Tae-Young Ahn ◽  
Seung-Pyo Hong ◽  
Seong-Il Kim ◽  
Young-Woon Kim
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Silver Nanoparticles ◽  
Real Time ◽  
Transmission Electron ◽  
Cell Transmission ◽  
Liquid Cell ◽  
Dependent Growth ◽  
Insight Into

Real-time liquid-cell transmission electron microscopy was utilized to gain insight into the growth and dissolution of silver nanoparticles.

Fabrication and investigation of core-sheath polymer/ polyaniline composite nanofibers

e-Polymers ◽  
2009 ◽  
Vol 9 (1) ◽  
Author(s):  
Huimin Huang ◽  
Zhenyu Li ◽  
Wei Wang ◽  
Fan Yang ◽  
Shangyu Li ◽  
...  
Keyword(s):  
Composite Nanofibers ◽  
In Situ Polymerization ◽  
Hydrophobic Polymer ◽  
Transmission Electron ◽  
Coaxial Fibers ◽  
Polymerization Conditions ◽  
Insight Into ◽  
Scanning Electron ◽  
Pan Fibers

AbstractThree types of coaxial polymer/polyaniline (PANi) fibers were prepared by in situ polymerization of aniline on the electrospun poly(methyl methacrylate) (PMMA), polystyrene (PS) and polyacrylonitrile (PAN) fibers, respectively. Scanning electron microscopy (SEM) and transmission electron microscope (TEM) were applied to characterize the morphologies of these core-sheath structures. Under identical polymerization conditions, a thicker layer of PANi was deposited on the hydrophilic PAN fibers than those on the other two hydrophobic polymer core fibers. The results revealed that the nature of the polymer cores could influence the formation of the coaxial fibers, which may provide a deeper insight into the formation of core-sheath nanostructures.

Direct observations of incipient plasticity during nanoindentation of Al

2004 ◽  
Vol 19 (1) ◽  
pp. 176-182 ◽  
Author(s):  
A.M. Minor ◽  
E.T. Lilleodden ◽  
E.A. Stach ◽  
J.W. Morris
Keyword(s):  
Crystalline Silicon ◽  
Dislocation Nucleation ◽  
Direct Observations ◽  
Transmission Electron ◽  
Incipient Plasticity ◽  
Grain Boundary Motion ◽  
Mechanisms Of Plastic Deformation ◽  
Insight Into

The mechanical testing technique for in situ nanoindentation in a transmission electron microscope is described and is shown to provide real-time observations of the mechanisms of plastic deformation that occur during nanoindentation. Here, the importance of this technique was demonstrated on an aluminum thin film deposited on a single-crystalline silicon substrate. Significant results include direct observation of dislocation nucleation, characterization of the dislocation distribution created by indentation, and the observation of indentation-induced grain boundary motion. The observations achieved by this technique provide unique insight into mechanical behavior studied with conventional instrumented nanoindentation techniques and also provide microstructural-level understanding of the mechanics of ultrasmall volumes.

scholarly journals “Endomicrobia”: Cytoplasmic Symbionts of Termite Gut Protozoa Form a Separate Phylum of Prokaryotes

2005 ◽  
Vol 71 (3) ◽  
pp. 1473-1479 ◽  
Author(s):  
Ulrich Stingl ◽  
Renate Radek ◽  
Hong Yang ◽  
Andreas Brune
Keyword(s):  
Sequence Similarity ◽  
Rrna Gene ◽  
16S Rrna Gene Sequences ◽  
Transmission Electron ◽  
Mutualistic Interaction ◽  
Candidate Species ◽  
And Function ◽  
Mutualistic Association ◽  
Group 1

ABSTRACT Lignocellulose digestion by wood-feeding termites depends on the mutualistic interaction of unusual, flagellate protists located in their hindgut. Most of the flagellates harbor numerous prokaryotic endosymbionts of so-far-unknown identity and function. Using a full-cycle molecular approach, we show here that the endosymbionts of the larger gut flagellates of Reticulitermes santonensis belong to the so-called termite group 1 (TG-1) bacteria, a group of clones previously obtained exclusively from gut homogenates of Reticulitermes speratus that are only distantly related to other bacteria and are considered a novel bacterial phylum based on their 16S rRNA gene sequences. Fluorescence in situ hybridization with specifically designed oligonucleotide probes confirmed that TG-1 bacteria are indeed located within the flagellate cells and demonstrated that Trichonympha agilis (Hypermastigida) and Pyrsonympha vertens (Oxymonadida) harbor phylogenetically distinct populations of symbionts (<95% sequence similarity). Transmission electron microscopy revealed that the symbionts are small, spindle-shaped cells (0.6 μm in length and 0.3 μm in diameter) surrounded by two membranes and located within the cytoplasm of their hosts. The symbionts of the two flagellates are described as candidate species in the candidate genus “Endomicrobium.” Moreover, we provide evidence that the members of the TG-1 phylum, for which we propose the candidate name “Endomicrobia,” are phylogenetically extremely diverse and are present in and also restricted to the guts of all lower termites and wood-feeding cockroaches of the genus Cryptocercus, the only insects that are in an exclusive, obligately mutualistic association with such unique cellulose-fermenting protists.

scholarly journals In situ TEM observation of the Boudouard reaction: multi-layered graphene formation from CO on cobalt nanoparticles at atmospheric pressure

2017 ◽  
Vol 197 ◽  
pp. 337-351 ◽  
Author(s):  
G. Marien Bremmer ◽  
Eirini Zacharaki ◽  
Anja O. Sjåstad ◽  
Violeta Navarro ◽  
Joost W. M. Frenken ◽  
...  
Keyword(s):  
Permanent Deformation ◽  
In Situ Tem ◽  
Boudouard Reaction ◽  
Final State ◽  
Transmission Electron ◽  
Co Dissociation ◽  
Co Nanoparticles ◽  
Cobalt Nanoparticle ◽  
Insight Into

Using a MEMS nanoreactor in combination with a specially designed in situ Transmission Electron Microscope (TEM) holder and gas supply system, we imaged the formation of multiple layers of graphene encapsulating a cobalt nanoparticle, at 1 bar CO : N2 (1 : 1) and 500 °C. The cobalt nanoparticle was imaged live in a TEM during the Boudouard reaction. The in situ/operando TEM studies give insight into the behaviour of the catalyst at the nanometer-scale, under industrially relevant conditions. When switching from Fischer–Tropsch syngas conditions (CO : H2 : N2 1 : 2 : 3 at 1 bar) to CO-rich conditions (CO : N2 1 : 1 at 1 bar), we observed the formation of multi-layered graphene on Co nanoparticles at 500 °C. Due to the high temperature, the surface of the Co nanoparticles facilitated the Boudouard reaction, causing CO dissociation and the formation of layers of graphene. After the formation of the first patches of graphene at the surface of the nanoparticle, more and more layers grew over the course of about 40 minutes. In its final state, around 10 layers of carbon capped the nanoparticle. During this process, the carbon shell caused mechanical stress in the nanoparticle, inducing permanent deformation.

In-Situ Electron Microscopy Studies of The Behavior of Metal Particles on Ceramic Substrates

1994 ◽  
Vol 357 ◽  
Author(s):  
R. Terry ◽  
K. Baker ◽  
Nelly M. Rodriguez
Keyword(s):  
Electron Microscopy ◽  
Morphological Characteristics ◽  
Metal Particles ◽  
Ceramic Substrates ◽  
Transmission Electron ◽  
In Situ Electron Microscopy ◽  
Metal Support Interaction ◽  
Metal Support ◽  
Insight Into

AbstractThis paper is devoted to a discussion of how the information derived from the application of in-situ transmission electron microscopy can be used to gain a unique insight into the manner by which various factors dictate the morphological characteristics of metal particles on a variety of ceramic substrates. In this context, we have used the technique to examine the influence of the strength of the metal-support interaction on the mode of sintering of small particles, and how the chemical nature of the gas environment can induce significant changes in the shapes of the metal particles in a given system. Attention is also focussed on the wetting behavior of metal particles dispersed on graphite when reacted in oxygen and how this aspect impacts on their subsequent mode of catalytic attack.

In Situ Dynamic Atomic-Level Investigation of a Weak Charge Transfer Lamellar Intercalation Process

1995 ◽  
Vol 404 ◽  
Author(s):  
L. Diebolt ◽  
R. Sharma ◽  
M. Mckelvy ◽  
W. S. Glaunsinger
Keyword(s):  
Charge Transfer ◽  
Nucleation And Growth ◽  
Atomic Level ◽  
Weak Charge ◽  
Intercalation Reaction ◽  
Transmission Electron ◽  
Environmental Cell ◽  
Reaction Processes ◽  
Insight Into

AbstractEnvironmental-cell dynamic high-resolution transmission electron microscopy (DHRTEM) has been used to provide atomic-level insight into lamellar reaction processes for the model weak- charge-transfer intercalation reaction of NH3 with 2H-TaS2. In situ intercalation was induced by exposing 2H-TaS2 crystallites to controlled pressures of NH3(g) and recorded on videotape with 0.03 second time resolution. The intercalation processes observed possess a strong similarity to nucleation and growth processes. Onset occurs in either outermost or internal guest galleries, with further intercalation of the galleries progressing away from the onset layers. Randomly staged regions, containing occasional packages of short-range order, were observed to form during the growth process.

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