scholarly journals Bacterial Nanotubes as Intercellular Linkages in Marine Assemblages

2021 ◽  
Vol 8 ◽  
Author(s):  
Nirav Patel ◽  
Yosuke Yamada ◽  
Farooq Azam
Keyword(s):  
Marine Bacteria ◽  
Structural Basis ◽  
Force Microscopy ◽  
Spatially Correlated ◽  
Spatial Coupling ◽  
Atomic Force ◽  
Transmission Electron ◽  
Cytoplasmic Content ◽  
And Function ◽  
Marine Microbial Communities

Several types of bacterial appendages, e.g., pili and fimbriae, are known for their role in promoting interactions and aggregation with particles and bacteria in the ocean. First discovered in Bacillus subtilis and Escherichia coli, but novel to marine bacteria, bacterial nanotubes are hollow tubular structures connecting cell pairs that allow for the internal transport of cytoplasmic metabolites across the connecting structure. While the significance of nanotubes in exchange of cytoplasmic content has been established in non-marine bacteria, their occurrence and potential ecological significance in marine bacteria has not been reported. Using multiple high-resolution microscopy methods (atomic force microscopy, scanning, and transmission electron microscopy), we have determined that marine bacteria isolates and natural assemblages from nearshore upper ocean waters can express bacterial nanotubes. In marine isolates Pseudoalteromonas sp. TW7 and Alteromonas sp. ALTSIO, individual bacterial nanotubes measured 50–160 nm in width and extended 100–600 nm between connected cells. The spatial coupling of different cells via nanotubes can last for at least 90 min, extending the duration of interaction events between marine bacteria within natural assemblages. The nanomechanical properties of bacterial nanotubes vary in adhesion and dissipation properties, which has implication for structural and functional variability of these structures in their ability to stick to surfaces and respond to mechanical forces. Nanotube frequency is low among cells in enriched natural assemblages, where nanotubes form short, intimate connections, <200 nm, between certain neighboring cells. Bacterial nanotubes can form the structural basis for a bacterial ensemble and function as a conduit for cytoplasmic exchange (not explicitly studied here) between members for multicellular coordination and expression. The structural measurements and nanomechanical analyses in this study also extends knowledge about the physical properties of bacterial nanotubes and their consequences for marine microenvironments. The discovery of nanotube expression in marine bacteria has significant potential implications regarding intimate bacterial interactions in spatially correlated marine microbial communities.

Scanning tunneling microscopy and atomic force microscopy: New tools for biology

1989 ◽  
Vol 47 ◽  
pp. 778-779
Author(s):  
CE Bracker ◽  
P. K. Hansma
Keyword(s):  
Physical Property ◽  
Scanning Probe ◽  
Scanning Tunneling ◽  
Small Scale ◽  
Tunneling Microscopy ◽  
Force Microscopy ◽  
New Family ◽  
Small Probe ◽  
Atomic Force ◽  
Transmission Electron

A new family of scanning probe microscopes has emerged that is opening new horizons for investigating the fine structure of matter. The earliest and best known of these instruments is the scanning tunneling microscope (STM). First published in 1982, the STM earned the 1986 Nobel Prize in Physics for two of its inventors, G. Binnig and H. Rohrer. They shared the prize with E. Ruska for his work that had led to the development of the transmission electron microscope half a century earlier. It seems appropriate that the award embodied this particular blend of the old and the new because it demonstrated to the world a long overdue respect for the enormous contributions electron microscopy has made to the understanding of matter, and at the same time it signalled the dawn of a new age in microscopy. What we are seeing is a revolution in microscopy and a redefinition of the concept of a microscope.Several kinds of scanning probe microscopes now exist, and the number is increasing. What they share in common is a small probe that is scanned over the surface of a specimen and measures a physical property on a very small scale, at or near the surface. Scanning probes can measure temperature, magnetic fields, tunneling currents, voltage, force, and ion currents, among others.

The Electrical Characterization and Physical Failure Analysis for Transistor Gate Leakage

2006 ◽  
Author(s):  
Tsung-Te Li ◽  
Chao-Chi Wu ◽  
Jung-Hsiang Chuang ◽  
Jon C. Lee
Keyword(s):  
Failure Analysis ◽  
Electrical Characterization ◽  
Physical Analysis ◽  
Gate Leakage ◽  
Force Microscopy ◽  
Atomic Force ◽  
Transmission Electron ◽  
Voltage Stress ◽  
Leakage Site

Abstract This article describes the electrical and physical analysis of gate leakage in nanometer transistors using conducting atomic force microscopy (C-AFM), nano-probing, transmission electron microscopy (TEM), and chemical decoration on simulated overstressed devices. A failure analysis case study involving a soft single bit failure is detailed. Following the nano-probing analysis, TEM cross sectioning of this failing device was performed. A voltage bias was applied to exaggerate the gate leakage site. Following this deliberate voltage overstress, a solution of boiling 10%wt KOH was used to etch decorate the gate leakage site followed by SEM inspection. Different transistor leakage behaviors can be identified with nano-probing measurements and then compared with simulation data for increased confidence in the failure analysis result. Nano-probing can be used to apply voltage stress on a transistor or a leakage path to worsen the weak point and then observe the leakage site easier.

Structural and Optical Properties of InAsSbBi Grown by Molecular Beam Epitaxy on Offcut GaSb Substrates

Photonics ◽  
2021 ◽  
Vol 8 (6) ◽  
pp. 215
Author(s):  
Rajeev R. Kosireddy ◽  
Stephen T. Schaefer ◽  
Marko S. Milosavljevic ◽  
Shane R. Johnson
Keyword(s):  
Molecular Beam Epitaxy ◽  
Molecular Beam ◽  
Optical Quality ◽  
X Ray Diffraction ◽  
Interface Quality ◽  
Force Microscopy ◽  
Atomic Force ◽  
Transmission Electron ◽  
Lateral Variations

Three InAsSbBi samples are grown by molecular beam epitaxy at 400 °C on GaSb substrates with three different offcuts: (100) on-axis, (100) offcut 1° toward [011], and (100) offcut 4° toward [011]. The samples are investigated using X-ray diffraction, Nomarski optical microscopy, atomic force microscopy, transmission electron microscopy, and photoluminescence spectroscopy. The InAsSbBi layers are 210 nm thick, coherently strained, and show no observable defects. The substrate offcut is not observed to influence the structural and interface quality of the samples. Each sample exhibits small lateral variations in the Bi mole fraction, with the largest variation observed in the on-axis growth. Bismuth rich surface droplet features are observed on all samples. The surface droplets are isotropic on the on-axis sample and elongated along the [011¯] step edges on the 1° and 4° offcut samples. No significant change in optical quality with offcut angle is observed.

scholarly journals Ultrafine metal-polymer catalysts based on polyconjugated systems for Fisher–Tropsch synthesis

2020 ◽  
Vol 92 (6) ◽  
pp. 977-984
Author(s):  
Mayya V. Kulikova ◽  
Albert B. Kulikov ◽  
Alexey E. Kuz’min ◽  
Anton L. Maximov
Keyword(s):  
Tropsch Synthesis ◽  
X Ray Diffraction ◽  
Fischer Tropsch ◽  
Force Microscopy ◽  
Composite Catalysts ◽  
Fe Catalyst ◽  
Atomic Force ◽  
And Function ◽  
Metal Polymer

AbstractFor previously studied Fischer–Tropsch nanosized Fe catalyst slurries, polymer compounds with or without polyconjugating structures are used as precursors to form the catalyst nanomatrix in situ, and several catalytic experiments and X-ray diffraction and atomic force microscopy measurements are performed. The important and different roles of the paraffin molecules in the slurry medium in the formation and function of composite catalysts with the two types of aforementioned polymer matrices are revealed. In the case of the polyconjugated polymers, the alkanes in the medium are “weakly” coordinated with the metal-polymer composites, which does not affect the effectiveness of the polyconjugated polymers. Otherwise, alkane molecules form a “tight” surface layer around the composite particles, which create transport complications for the reagents and products of Fischer-Tropsch synthesis and, in some cases, can change the course of the in situ catalyst formation.

Cross-bridge cycling gives rise to spatiotemporal heterogeneity of dynamic subcellular mechanics in cardiac myocytes probed with atomic force microscopy

2010 ◽  
Vol 298 (3) ◽  
pp. H853-H860 ◽  
Author(s):  
Evren U. Azeloglu ◽  
Kevin D. Costa
Keyword(s):  
Contractile Activity ◽  
Major Axis ◽  
Neonatal Rat ◽  
Pharmacological Treatments ◽  
Rat Cardiomyocytes ◽  
Force Microscopy ◽  
Cross Bridge ◽  
Apparent Modulus ◽  
Atomic Force ◽  
And Function

To study how the dynamic subcellular mechanical properties of the heart relate to the fundamental underlying process of actin-myosin cross-bridge cycling, we developed a novel atomic force microscope elastography technique for mapping spatiotemporal stiffness of isolated, spontaneously beating neonatal rat cardiomyocytes. Cells were indented repeatedly at a rate close but unequal to their contractile frequency. The resultant changes in pointwise apparent elastic modulus cycled at a predictable envelope frequency between a systolic value of 26.2 ± 5.1 kPa and a diastolic value of 7.8 ± 4.1 kPa at a representative depth of 400 nm. In cells probed along their major axis, spatiotemporal changes in systolic stiffness displayed a heterogeneous pattern, reflecting the banded sarcomeric structure of underlying myofibrils. Treatment with blebbistatin eliminated contractile activity and resulted in a uniform apparent modulus of 6.5 ± 4.8 kPa. This study represents the first quantitative dynamic mechanical mapping of beating cardiomyocytes. The technique provides a means of probing the micromechanical effects of disease processes and pharmacological treatments on beating cardiomyocytes, providing new insights and relating subcellular cardiac structure and function.

Microscopic studies of fast phase transformations in GeSbTe films

2001 ◽  
Vol 674 ◽  
Author(s):  
Ralf Detemple ◽  
Inés Friedrich ◽  
Walter Njoroge ◽  
Ingo Thomas ◽  
Volker Weidenhof ◽  
...  
Keyword(s):  
Phase Transformation ◽  
Data Transfer ◽  
Optical Measurements ◽  
Transfer Rates ◽  
Force Microscopy ◽  
High Data ◽  
Atomic Force ◽  
Transmission Electron ◽  
Future Success ◽  
Microscopic Studies

ABSTRACTVital requirements for the future success of phase change media are high data transfer rates, i.e. fast processes to read, write and erase bits of information. The understanding and optimization of fast transformations is a considerable challenge since the processes only occur on a submicrometer length scale in actual bits. Hence both high temporal and spatial resolution is needed to unravel the essential details of the phase transformation. We employ a combination of fast optical measurements with microscopic analyses using atomic force microscopy (AFM) and transmission electron microscopy (TEM). The AFM measurements exploit the fact that the phase transformation from amorphous to crystalline is accompanied by a 6% volume reduction. This enables a measurement of the vertical and lateral speed of the phase transformation. Several examples will be presented showing the information gained by this combination of techniques.

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