SPICE Modeling and Characterization of Filament Formation Perovskite Memristors

2020 ◽  
Author(s):  
Ivan Shmarov ◽  
Pablo Docampo ◽  
Thomas Billam ◽  
Rishad Shafik
Keyword(s):  
Filament Formation

Spatiotemporal characterization of the field-induced insulator-to-metal transition

Science ◽  
2021 ◽  
pp. eabd9088
Author(s):  
Javier del Valle ◽  
Nicolas M. Vargas ◽  
Rodolfo Rocco ◽  
Pavel Salev ◽  
Yoav Kalcheim ◽  
...  
Keyword(s):  
Electric Field ◽  
Time Resolution ◽  
Growth Dynamics ◽  
Metallic Phase ◽  
Resistivity Change ◽  
Filament Formation ◽  
Correlated Systems ◽  
In Operando ◽  
Crucial Parameter

Many correlated systems feature an insulator-to-metal transition that can be triggered by an electric field. Although it is known that metallization takes place through filament formation, the details of how this process initiates and evolves remain elusive. We use in-operando optical reflectivity to capture the growth dynamics of the metallic phase with space and time resolution. We demonstrate that filament formation is triggered by nucleation at hotspots, with a subsequent expansion over several decades in time. By comparing three case studies (VO2, V3O5 and V2O3), we identify the resistivity change across the transition as the crucial parameter governing this process. Our results provide a spatiotemporal characterization of volatile resistive switching in Mott insulators, key for emerging technologies such as optoelectronics or neuromorphic computing.

scholarly journals Fluorescence assays for F-pili and their application

Microbiology ◽  
2005 ◽  
Vol 151 (11) ◽  
pp. 3541-3548 ◽  
Author(s):  
Katrin Daehnel ◽  
Robin Harris ◽  
Lucinda Maddera ◽  
Philip Silverman
Keyword(s):  
Primary Structure ◽  
Type Iv Secretion ◽  
Filament Formation ◽  
Secretion Systems ◽  
Type Iv ◽  
Bacteriophage Infection ◽  
And Function ◽  
Domain I ◽  
Donor Activity

Conjugative pili are extracellular filaments elaborated by Gram-negative bacteria expressing certain type IV secretion systems. They are required at the earliest stages of conjugal DNA transfer to establish specific and secure cell–cell contacts. Conjugative pili also serve as adsorption organelles for both RNA and DNA bacteriophages. Beyond these facts, the structure, formation and function of these filaments are poorly understood. This paper describes a rapid, quantitative assay for F-pili encoded by the F plasmid type IV secretion system. The assay is based on the specific lateral adsorption of icosahedral RNA bacteriophage R17 by F-pili. Bacteriophage particles conjugated with a fluorescent dye, Alexa 488, and bound to F-pili defined filaments visible by immunofluorescence microscopy. F-pili attached to F+ cells and free F-pili were both visible by this method. For quantification, cell-bound bacteriophage were separated from free bacteriophage particles by sedimentation and released by suspending cell pellets in 0·1 % SDS. Fluorescence in cell-free supernatant fractions was measured by fluorometry. The authors present a characterization of this assay and its application to F-pilus formation by cells carrying mutations in the gene for the F-pilus subunit F-pilin. Each mutation introduced a cysteine, which F-pilin normally lacks, at a different position in its primary structure. Cysteine residues in the N-terminal domain I abolished filament formation as measured by fluorescent R17 binding. This was confirmed by measurements of DNA donor activity and filamentous DNA bacteriophage infection. With one exception (G53C), cysteines elsewhere in the F-pilin primary structure did not abolish filament formation, although some mutations differentially affected F-pilus functions.

scholarly journals Characterization of AIM2 DNA-Binding Properties and Filament Formation

2015 ◽  
Vol 108 (2) ◽  
pp. 401a
Author(s):  
Seamus Morrone ◽  
Mariusz Matyszewski ◽  
Jungsan Sohn
Keyword(s):  
Dna Binding ◽  
Filament Formation ◽  
Binding Properties ◽  
Dna Binding Properties

scholarly journals Biochemical characterization of a human septin octamer

2021 ◽  
Author(s):  
Martin Fischer ◽  
Dominik Frank ◽  
Reinhild Roesler ◽  
Nils Johnsson ◽  
Thomas Gronemeyer
Keyword(s):  
Actin Polymerization ◽  
Biochemical Characterization ◽  
Small Gtpases ◽  
Filament Formation ◽  
Gtp Hydrolysis ◽  
Ordered Structures ◽  
E Coli ◽  
Exchange Properties

Septins are part of the cytoskeleton and polymerize into non-polar filaments of heteromeric hexamers or octamers. They belong to the class of P-loop GTPases but the roles of GTP binding and hydrolysis on filament formation and dynamics are not well understood. The basic human septin building block is the septin rod, a hetero-octamer composed of SEPT2, SEPT6, SEPT7, and SEPT9 with a stoichiometry of 2:2:2:2 (2-7-6-9-9-6-7-2). Septin rods polymerize by end-to-end and lateral joining into linear filaments and higher ordered structures such as rings, sheets, and gauzes. We purified a recombinant human septin octamer from E. coli for in vitro experimentation that is able to polymerize into filaments. We could show that the C-terminal region of the central SEPT9 subunit contributes to filament formation and that the human septin rod decreases the rate of in vitro actin polymerization. We provide further first kinetic data on the nucleotide uptake- and exchange properties of human hexameric and octameric septin rods. We could show that nucleotide uptake prior to hydrolysis is a dynamic process and that a bound nucleotide is exchangeable. However, the hydrolyzed gamma-phosphate is not released from the native protein complex. We consequently propose that GTP hydrolysis in human septins does not follow the typical mechanism known from other small GTPases.

Analytically and empirically consistent characterization of resistive switching mechanism in Ag conducting-bridge random-access memory through pseudo-liquid approach

2021 ◽  
Author(s):  
Yeon-Joon Choi ◽  
Suhyun Bang ◽  
Tae-Hyeon Kim ◽  
Kyungho Hong ◽  
Sungjoon Kim ◽  
...  
Keyword(s):  
Resistive Switching ◽  
Random Access ◽  
Random Access Memory ◽  
Physical Analysis ◽  
Filament Formation ◽  
Access Memory ◽  
Metal Bonding ◽  
Conducting Bridge ◽  
Resistive Switching Mechanism

A new physical analysis of the filament formation in Ag conducting-bridge random-access memory (CBRAM) in consideration of the existence of inter-atomic attractions caused by metal bonding is suggested. The movement...

Isolation and Characterization of the Cryptococcus neoformans MATa Pheromone Gene

Genetics ◽  
2002 ◽  
Vol 160 (3) ◽  
pp. 935-947
Author(s):  
Carol M McClelland ◽  
Jianmin Fu ◽  
Gay L Woodlee ◽  
Tara S Seymour ◽  
Brian L Wickes
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Amino Acids ◽  
Cryptococcus Neoformans ◽  
Mating Types ◽  
Filament Formation ◽  
Gene Encoding ◽  
Conserved Sequence ◽  
Isolation And Characterization ◽  
Conserved Genes

Abstract Cryptococcus neoformans is a heterothallic basidiomycete with two mating types, MATa and MATα. The mating pathway of this fungus has a number of conserved genes, including a MATα-specific pheromone (MFα1). A modified differential display strategy was used to identify a gene encoding the MATa pheromone. The gene, designated MFa1, is 42 amino acids in length and contains a conserved farnesylation motif. MFa1 is present in three linked copies that span a 20-kb fragment of MATa-specific DNA and maps to the MAT-containing chromosome. Transformation studies showed that MFa1 induced filament formation only in MATα cells, demonstrating that MFa1 is functionally conserved. Sequence analysis of the predicted Mfa1 and Mfα1 proteins revealed that, in contrast to other fungi such as Saccharomyces cerevisiae, the C. neoformans pheromone genes are structurally and functionally conserved. However, unlike the MFα1 gene, which is found in MATα strains of both varieties of C. neoformans, MFa1 is specific for the neoformans variety of C. neoformans.

scholarly journals Dynamics of Tpm1.8 domains on actin filaments with single-molecule resolution

2020 ◽  
Vol 31 (22) ◽  
pp. 2452-2462
Author(s):  
Ilina Bareja ◽  
Hugo Wioland ◽  
Miro Janco ◽  
Philip R. Nicovich ◽  
Antoine Jégou ◽  
...  
Keyword(s):  
Actin Filament ◽  
Single Molecule ◽  
Actin Filaments ◽  
Filament Formation ◽  
Filament Dynamics ◽  
Kinetics Of ◽  
Insight Into

Characterization of the kinetics of Tpm1.8 binding to actin filaments with single-molecule resolution. This work provides molecular insight into actin–tropomyosin filament formation and the role of tropomyosins in regulating actin filament dynamics.

Morphological Characterization of Mycobacteriophage R1

1974 ◽  
Vol 32 ◽  
pp. 254-255
Author(s):  
B. L. Soloff ◽  
T. A. Rado
Keyword(s):  
Carbon Source ◽  
Stationary Phase ◽  
Growth Phase ◽  
Minimal Medium ◽  
Morphological Characterization ◽  
Logarithmic Growth Phase ◽  
Complete Lysis ◽  
Lysogenic Culture ◽  
Logarithmic Growth

Mycobacteriophage R1 was originally isolated from a lysogenic culture of M. butyricum. The virus was propagated on a leucine-requiring derivative of M. smegmatis, 607 leu−, isolated by nitrosoguanidine mutagenesis of typestrain ATCC 607. Growth was accomplished in a minimal medium containing glycerol and glucose as carbon source and enriched by the addition of 80 μg/ ml L-leucine. Bacteria in early logarithmic growth phase were infected with virus at a multiplicity of 5, and incubated with aeration for 8 hours. The partially lysed suspension was diluted 1:10 in growth medium and incubated for a further 8 hours. This permitted stationary phase cells to re-enter logarithmic growth and resulted in complete lysis of the culture.

AEM analysis of crystallization in Ti-based amorphous alloys

1983 ◽  
Vol 41 ◽  
pp. 270-271
Author(s):  
A.R. Pelton ◽  
A.F. Marshall ◽  
Y.S. Lee
Keyword(s):  
Magnetic Properties ◽  
Amorphous Alloys ◽  
Amorphous Materials ◽  
Isothermal Annealing ◽  
Amorphous Matrix ◽  
Nucleation And Growth ◽  
Current Interest ◽  
Amorphous Films ◽  
Electrical And Magnetic Properties

Amorphous materials are of current interest due to their desirable mechanical, electrical and magnetic properties. Furthermore, crystallizing amorphous alloys provides an avenue for discerning sequential and competitive phases thus allowing access to otherwise inaccessible crystalline structures. Previous studies have shown the benefits of using AEM to determine crystal structures and compositions of partially crystallized alloys. The present paper will discuss the AEM characterization of crystallized Cu-Ti and Ni-Ti amorphous films.Cu60Ti40: The amorphous alloy Cu60Ti40, when continuously heated, forms a simple intermediate, macrocrystalline phase which then transforms to the ordered, equilibrium Cu3Ti2 phase. However, contrary to what one would expect from kinetic considerations, isothermal annealing below the isochronal crystallization temperature results in direct nucleation and growth of Cu3Ti2 from the amorphous matrix.

Characterization of Coherent, Ordered Precipitates in Nickel-Base Alloys

1973 ◽  
Vol 31 ◽  
pp. 144-145
Author(s):  
B. H. Kear ◽  
J. M. Oblak
Keyword(s):  
Stable Phase ◽  
Nickel Base Superalloy ◽  
Alloy 718 ◽  
Commercial Alloy ◽  
Precipitate Morphology ◽  
Continuous Precipitation ◽  
Nickel Base ◽  
Base Superalloy ◽  
Strengthening Precipitate

A nickel-base superalloy is essentially a Ni/Cr solid solution hardened by additions of Al (Ti, Nb, etc.) to precipitate a coherent, ordered phase. In most commercial alloy systems, e.g. B-1900, IN-100 and Mar-M200, the stable precipitate is Ni3 (Al,Ti) γ′, with an LI2structure. In A lloy 901 the normal precipitate is metastable Nis Ti3 γ′ ; the stable phase is a hexagonal Do2 4 structure. In Alloy 718 the strengthening precipitate is metastable γ″, which has a body-centered tetragonal D022 structure.Precipitate MorphologyIn most systems the ordered γ′ phase forms by a continuous precipitation re-action, which gives rise to a uniform intragranular dispersion of precipitate particles. For zero γ/γ′ misfit, the γ′ precipitates assume a spheroidal.

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