Search results for "Forming"
showing 10 items of 1719 documents
Pore formation by Vibrio cholerae cytolysin requires cholesterol in both monolayers of the target membrane
2007
Vibrio cholerae cytolysin (VCC) forms oligomeric transmembrane pores in cholesterol-rich membranes. To better understand this process, we used planar bilayer membranes. In symmetric membranes, the rate of the channel formation by VCC has a superlinear dependency on the cholesterol membrane fraction. Thus, more than one cholesterol molecule can facilitate VCC-pore formation. In asymmetric membranes, the rate of pore formation is limited by the leaflet with the lower cholesterol content. Methyl-beta-cyclodextrin, which removes cholesterol from membranes, rapidly inhibits VCC pore formation, even when it is added to the side opposite that of VCC addition. The results suggest that cholesterol i…
Correct oligomerization is a prerequisite for insertion of the central molecular domain of staphylococcal α-toxin into the lipid bilayer
1995
Staphylococcal alpha-toxin is a primarily hydrophilic molecule that binds as a monomer to target membranes and then aggregates to form amphiphilic oligomers that represent water-filled transmembrane channels. Current evidence indicates that a region located in the center of the molecule inserts deeply into the bilayer. In the present study, we sought to determine whether membrane insertion was triggered by the oligomerization process, and whether insertion correlated with pore formation. Double mutants of alpha-toxin were prepared in which His-35 was replaced by Arg, and cysteine residues were introduced at positions 69, 130 and 186. Substitution of His-35 with Arg rendered the toxin molecu…
Mode of primary binding to target membranes and pore formation induced by Vibrio cholerae cytolysin (hemolysin).
1997
Vibrio cholerae cytolysin (VCC) is produced by many non-choleratoxigenic strains of V. cholerae, and possibly represents a relevant pathogenicity determinant of these bacteria. The protein is secreted as a pro-toxin that is proteolytically cleaved to yield the active toxin with a molecular mass of approximately 63 kDa. We here describe a simple procedure for preparative isolation of mature VCC from bacterial culture supernatants, and present information on its mode of binding and pore formation in biological membranes. At low concentrations, toxin monomers interact with a high-affinity binding site on highly susceptible rabbit erythrocytes. This as yet unidentified binding site is absent on…
Cholesterol Specificity of Some Heptameric β-Barrel Pore-Forming Bacterial Toxins: Structural and Functional Aspects
2010
Apart from the thiol-specific/cholesterol-dependent cytolysin family of toxins (see Chapter 20) there are a number of other unrelated bacterial toxins that also have an affinity for plasma membrane cholesterol. Emphasis is given here on the Vibrio cholerae cytolysin (VCC) and the cytolysins from related Vibrio species. The inhibition of the cytolytic activity of these toxins by prior incubation with extracellular cholesterol or low density lipoprotein emerges as a unifying feature, as does plasma membrane cholesterol depletion. Incubation of VCC with cholesterol produces a heptameric oligomer, which is not equivalent to the pre-pore since it is unable to penetrate the plasma membrane. In st…
Figuration de la violence indicible dans des compositions espagnoles contemporaines : recherche esthétique et/ou témoignage du sensible
2017
National audience
Potentials of Togetherness: Beyond Individualism and Community in Nordic Art Education
2013
Historically, art education has focused mainly on individual learning processes. In Nordic countries,' for example, discourses of training the rational individual through skills of objective representation, developing the authentic individual through child-centered education, or stimulating identity-processes through critical pedagogy have dominated over ideas of collectivity, community, and society (llleris, 2002; Kjosavik, 2001; Lindstrom, 2009; Pedersen, 1998; Pohjakallio, 1998). Today, poststructuralist theories of subjectivity and subjectivation are challenging these modernist discourses by proposing more dynamic models of multiple and instable learning selves, always in the making (e.…
Severe plastic deformation (SPD) processes for metals
2008
Abstract Processes of severe plastic deformation (SPD) are defined as metal forming processes in which a very large plastic strain is imposed on a bulk process in order to make an ultra-fine grained metal. The objective of the SPD processes for creating ultra-fine grained metal is to produce lightweight parts by using high strength metal for the safety and reliability of micro-parts and for environmental harmony. In this keynote paper, the fabrication process of equal channel angular pressing (ECAP), accumulative roll-bonding (ARB), high pressure torsion (HPT), and others are introduced, and the properties of metals processed by the SPD processes are shown. Moreover, the combined processes …
Undergraduate students’ strategies for negotiating emerging performer and teacher identities
2017
Nowadays, instrumental undergraduate students must often negotiate their emerging performer and teacher identities, and the results of this process affect the way they later balance their professional and personal life and their ability to sustain lifelong involvement in music. Drawing from recent sociological studies on bicultural identity integration, this study addresses two research questions: What strategies do undergraduate students adopt for negotiating both professional identities? And what are the characteristics of each strategy?One hundred and twenty-one undergraduate performance students participated in this study. Using cluster analysis, a typology of eight strategies for negot…
Study of the synergistic interaction between nickel, gold and molybdenum in novel modified NiO/GDC cermets, possible anode materials for CH4 fueled S…
2013
Abstract The present study concerns the structural and physicochemical characterization of novel Au–Mo–NiO/GDC cermets, alongside with measurements of their carbon tolerance. This is an investigation on whether commercially available NiO/GDC powder that is modified with Au and/or Mo can yield possible electrocatalysts as anodes for CH4 fueled SOFCs. Specifically, the performed preparation methods of deposition-precipitation and deposition-coprecipitation permitted the modification of a commercial electrocatalyst and lead to cermets that exhibit different reaction kinetics for the catalytic dissociation of CH4 and different performance for CH4 steam reforming. The most interesting structural…
Incremental forming using KUKA KR210-2 industrial robot - research regarding design rules and process modelling
2021
Incremental sheet forming (ISF) process show a great potential in the manufacturing of small series production or prototype development parts. One of the sheet metal forming process, where the contact between punch and metal sheet is in a single point, is known as single point incremental forming (SPIF). The part is manufacture with a simple tool, known as punch, that performs a series of combined movements on the vertically and horizontally directions. The paper introduces a study regarding the design rules and process modelling of this unconventional process, by means of a KUKA KR210-2 industrial robot as technological equipment able to control the correlated movement of the punch. Supple…