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Ronsin O, Caroli C, Baumberger T. Preferential hydration fully controls the renaturation dynamics of collagen in water-glycerol solvents. Eur Phys J E Soft Matter 2017; 40:55. [PMID: 28480496 DOI: 10.1140/epje/i2017-11545-1] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/14/2017] [Accepted: 04/20/2017] [Indexed: 06/07/2023]
Abstract
Glycerol is one of the additives which stabilize collagen, as well as globular proteins, against thermally induced denaturation --an effect explained by preferential hydration, i.e. by the formation, in water/glycerol solvents, of a hydration layer whose entropic cost favors the more compact triple-helix native structure against the denatured one, gelatin. Quenching gelatin solutions promotes renaturation which, however, remains incomplete, as the formation of a gel network gives rise to growing topological constraints. So, gelatin gels exhibit glass-like dynamical features such as slow aging of their shear modulus and stretched exponential stress relaxation, the study of which gives us access to the re(de)naturation dynamics of collagen. We show that this dynamics is independent of the bulk solvent viscosity and controlled by a single parameter, the undercooling [Formula: see text] below the glycerol-concentration-dependent denaturation temperature. This provides direct proof of i) the presence of a nanometer thick, glycerol-free hydration layer, ii) the high locality of the kinetically limiting process governing renaturation.
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Affiliation(s)
- O Ronsin
- Institut des Nanosciences de Paris, Sorbonne universités, UPMC univ Paris 6 and CNRS-UMR 7588, 4 place Jussieu, F-75252, Paris, France.
| | - C Caroli
- Institut des Nanosciences de Paris, Sorbonne universités, UPMC univ Paris 6 and CNRS-UMR 7588, 4 place Jussieu, F-75252, Paris, France
| | - T Baumberger
- Institut des Nanosciences de Paris, Sorbonne universités, UPMC univ Paris 6 and CNRS-UMR 7588, 4 place Jussieu, F-75252, Paris, France
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Ronsin O, Caroli C, Baumberger T. Glass-like dynamics of the strain-induced coil/helix transition on a permanent polymer network. J Chem Phys 2016; 144:064904. [DOI: 10.1063/1.4941456] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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Souguir H, Ronsin O, Caroli C, Baumberger T. Two-step build-up of a thermoreversible polymer network: From early local to late collective dynamics. Phys Rev E Stat Nonlin Soft Matter Phys 2015; 91:042305. [PMID: 25974489 DOI: 10.1103/physreve.91.042305] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/20/2015] [Indexed: 06/04/2023]
Abstract
We probe the mechanisms at work in the build-up of thermoreversible gel networks, with the help of hybrid gelatin gels containing a controlled density of irreversible, covalent crosslinks (CLs), which we quench below the physical gelation temperature. The detailed analysis of the dependence on covalent crosslink density of both the shear modulus and optical activity evolutions with time after quench enables us to identify two stages of the physical gelation process, separated by a temperature-dependent crossover modulus: (i) an early nucleation regime during which rearrangements of the triple-helix CLs play a negligible role, and (ii) a late, logarithmic aging one, which is preserved, though slowed down, in the presence of irreversible CLs. We show that aging is fully controlled by rearrangements and discuss the implication of our results in terms of the switch from an early, local dynamics to a late, cooperative long-range one.
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Affiliation(s)
- H Souguir
- Institut des Nanosciences de Paris (INSP), Université Paris 6, UMR CNRS 7588, 2 place Jussieu, 75005 Paris, France
| | - O Ronsin
- Institut des Nanosciences de Paris (INSP), Université Paris 6, UMR CNRS 7588, 2 place Jussieu, 75005 Paris, France
| | - C Caroli
- Institut des Nanosciences de Paris (INSP), Université Paris 6, UMR CNRS 7588, 2 place Jussieu, 75005 Paris, France
| | - T Baumberger
- Institut des Nanosciences de Paris (INSP), Université Paris 6, UMR CNRS 7588, 2 place Jussieu, 75005 Paris, France
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Giorgi MA, Caroli C, Micone P, Giglio ND, Aiello E, Donato B, Mould J, Radero G, Casas M. Estimation of the effectiveness of apixaban in non valvular atrial fibrillation in anticoagulant suitable population in Argentina. Eur Heart J 2013. [DOI: 10.1093/eurheartj/eht309.p3351] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
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Ronsin O, Caroli C, Baumberger T. Microstructuration stages during gelation of gelatin under shear. Eur Phys J E Soft Matter 2011; 34:61. [PMID: 21701962 DOI: 10.1140/epje/i2011-11061-4] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/25/2011] [Revised: 03/22/2011] [Accepted: 06/01/2011] [Indexed: 05/31/2023]
Abstract
We study gelation under shear of aqueous gelatin by measuring the evolution of the apparent viscosity, thus extending the previous study by de Carvalho and Djabourov (W. de Carvalho, M. Djabourov, Rheol. Acta 36, 591 (1997)). From a set of experiments under constant stress, we deduce that the microstructure evolves through the following succession of regimes: i) nucleation and growth until crowding of a microgel suspension; ii) coalescence into strata parallel to the flow; iii) gradual thickening of these strata via transverse cross-linking until the flow finally localizes into two interfacial sliding bands which close sequentially. The transition between these regimes occurs at characteristic viscosity values. This scenario is fully confirmed by experiments performed at constant shear rates. We expect it to be relevant for all materials forming thermoreversible gels.
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Affiliation(s)
- O Ronsin
- Institut des Nanosciences de Paris, Université Pierre et Marie Curie, Paris, France.
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Reinecke EA, Bentaib A, Kelm S, Jahn W, Meynet N, Caroli C. Open issues in the applicability of recombiner experiments and modelling to reactor simulations. Progress in Nuclear Energy 2010. [DOI: 10.1016/j.pnucene.2009.09.010] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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Ronsin O, Caroli C, Baumberger T. Interplay between shear loading and structural aging in a physical gelatin gel. Phys Rev Lett 2009; 103:138302. [PMID: 19905546 DOI: 10.1103/physrevlett.103.138302] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/04/2009] [Indexed: 05/28/2023]
Abstract
We show that the aging of the mechanical relaxation of a gelatin gel exhibits the same scaling phenomenology as polymer and colloidal glasses. In addition, gelatin is known to exhibit logarithmic structural aging (stiffening). We find that stress accelerates this process. However, this effect is definitely irreducible to a mere age shift with respect to natural aging. We suggest that it is interpretable in terms of elastically aided elementary (coil --> helix) local events whose dynamics gradually slows down as aging increases geometric frustration.
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Affiliation(s)
- O Ronsin
- INSP, UPMC Université Paris 06, CNRS UMR 7588, 75015 Paris, France
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Baumberger T, Caroli C, Martina D, Ronsin O. Magic angles and cross-hatching instability in hydrogel fracture. Phys Rev Lett 2008; 100:178303. [PMID: 18518345 DOI: 10.1103/physrevlett.100.178303] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/09/2008] [Indexed: 05/26/2023]
Abstract
The full 2D analysis of roughness profiles of fracture surfaces resulting from quasistatic crack propagation in gelatin gels reveals an original behavior characterized by (i) strong anisotropy with maximum roughness at V-independent symmetry-preserving angles and (ii) a subcritical instability leading, below a critical velocity, to a cross-hatched regime due to straight macrosteps drifting at the same magic angles and nucleated on crack-pinning network inhomogeneities. Step height values are determined by the width of the strain-hardened zone, governed by the elastic crack blunting characteristic of soft solids with breaking stresses much larger than low strain moduli.
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Affiliation(s)
- T Baumberger
- INSP, UPMC Université Paris 06, CNRS UMR 7588, 140 rue de Lourmel, 75015 Paris, France
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Kudriakov S, Dabbene F, Studer E, Beccantini A, Magnaud J, Paillère H, Bentaib A, Bleyer A, Malet J, Porcheron E, Caroli C. The TONUS CFD code for hydrogen risk analysis: Physical models, numerical schemes and validation matrix. Nuclear Engineering and Design 2008. [DOI: 10.1016/j.nucengdes.2007.02.048] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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Benigni A, Caroli C, Longaretti L, Gagliardini E, Zoja C, Galbusera M, Moioli D, Romagnani P, Tincani A, Andreoli L, Remuzzi G. Involvement of renal tubular Toll-like receptor 9 in the development of tubulointerstitial injury in systemic lupus. ACTA ACUST UNITED AC 2007; 56:1569-78. [PMID: 17469139 DOI: 10.1002/art.22524] [Citation(s) in RCA: 52] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
OBJECTIVE Toll-like receptor 9 (TLR-9), a receptor for CpG DNA, has been implicated in the activation of immune cells in lupus. We undertook this study to determine whether the expression of TLR-9 in resident renal cells in lupus nephritis is related to the development of tubulointerstitial injury. METHODS TLR-9 was analyzed in selectively retrieved renal tissue from (NZB x NZW)F1 mice at different stages of disease by laser capture microdissection combined with real-time quantitative reverse transcriptase-polymerase chain reaction, and in renal biopsy specimens from lupus nephritis patients by immunohistochemistry. We investigated for the molecular component responsible for TLR-9 activation by cultured proximal tubular cells in serum from patients with lupus. RESULTS Renal tissue from NZB x NZW mice displayed robust TLR-9 expression localized to proximal tubular cells. TLR-9 levels correlated with proteinuria and tubulointerstitial injury to the extent that a cyclin-dependent kinase inhibitor, while reducing proteinuria and renal structural damage, prevented tubular TLR-9 generation in lupus mice. Consistently, exaggerated TLR-9 staining was found in proximal tubular cells of lupus patients, which correlated with tubulointerstitial damage. DNA-containing immune complexes purified from sera of patients with lupus induced TLR-9 in cultured proximal tubular cells. This was prevented by CCGG-rich short oligonucleotides, specific antagonists of CpG DNA, indicating that the DNA component of immune complexes was required for TLR-9 stimulation. CONCLUSION These findings suggest that tubular TLR-9 activation has a pathogenetic role in tubulointerstitial inflammation and damage in experimental and human lupus nephritis, and they indicate a novel target for future therapies.
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MESH Headings
- Animals
- Biopsy
- Cells, Cultured
- Female
- Gene Expression Regulation/drug effects
- Humans
- Kidney Tubules, Proximal/metabolism
- Kidney Tubules, Proximal/pathology
- Lupus Erythematosus, Systemic/complications
- Lupus Erythematosus, Systemic/genetics
- Lupus Erythematosus, Systemic/metabolism
- Mice
- Mice, Inbred NZB
- Mice, Inbred Strains
- Nephritis, Interstitial/etiology
- Nephritis, Interstitial/genetics
- Nephritis, Interstitial/metabolism
- Protein Kinase Inhibitors/pharmacology
- Purines/pharmacology
- RNA, Messenger/genetics
- RNA, Messenger/metabolism
- Roscovitine
- Toll-Like Receptor 9/genetics
- Toll-Like Receptor 9/metabolism
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Affiliation(s)
- Ariela Benigni
- Mario Negri Institute for Pharmacological Research, Bergamo, Italy.
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Baumberger T, Caroli C, Martina D. Fracture of a biopolymer gel as a viscoplastic disentanglement process. Eur Phys J E Soft Matter 2006; 21:81-9. [PMID: 17093896 DOI: 10.1140/epje/i2006-10048-6] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/29/2006] [Accepted: 10/12/2006] [Indexed: 05/12/2023]
Abstract
We present an extensive experimental study of mode-I, steady, slow crack dynamics in gelatin gels. Taking advantage of the sensitivity of the elastic stiffness to gel composition and history we confirm and extend the model for fracture of physical hydrogels which we proposed in a previous paper (Nature Mater. 5, 552 (2006)), which attributes decohesion to the viscoplastic pull-out of the network-constituting chains. So, we propose that, in contrast with chemically cross-linked ones, reversible gels fracture without chain scission.
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Affiliation(s)
- T Baumberger
- UMR 7588, Campus Boucicaut, INSP, Université Pierre et Marie Curie-Paris 6, Université Denis Diderot-Paris 7, CNRS, 140 rue de Lourmel, 75015, Paris, France.
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Abstract
We report on the frictional properties of a single contact between a glassy polymer lens and a flat silica substrate covered either by a disordered or by a self-assembled alkylsilane monolayer. We find that, in contrast to a widely spread belief, the Amontons proportionality between frictional and normal stresses does not hold. Besides, we observe that the velocity dependence of the sliding stress is strongly sensitive to the structure of the silane layer. Analysis of the frictional rheology observed on both disordered and self-assembled monolayers suggests that dissipation is controlled by the plasticity of a glass-like interfacial layer in the former case, and by pinning of polymer chains on the substrate in the latter one.
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Affiliation(s)
- L Bureau
- Institut des Nanosciences de Paris, UMR 7588 CNRS-Université Paris 6, 140 rue de Lourmel, 75015, Paris, France.
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Abstract
We study the reflection of an acoustic plane wave from a steadily sliding planar interface with velocity-strengthening friction or a shear band in a confined granular medium. The corresponding acoustic impedance is utterly different from that of the static interface. In particular, the system being open, the energy of an in-plane polarized wave is no longer conserved, the work of the external pulling force being partitioned between frictional dissipation and gain (of either sign) of coherent acoustic energy. Large values of the friction coefficient favor energy gain, while velocity strengthening tends to suppress it. An interface with infinite elastic contrast (one rigid medium) and v-independent (Coulomb) friction exhibits spontaneous acoustic emission, as already shown by Nosonovsky and Adams [Int. J. Eng. Sci. 39, 1257 (2001)]. But this pathology is cured by a moderately large V strengthening of friction, or, for systems with not too large friction coefficients, by any finite elastic contrast. We show that (i) positive gain should be observable for rough-on-flat multicontact interfaces and (ii) a sliding shear band in a granular medium should give rise to sizable reflection, which opens a promising possibility for the detection of shear localization.
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Affiliation(s)
- C Caroli
- Groupe de Physique des Solides, Paris, France
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Affiliation(s)
- L Bureau
- Groupe de Physique des Solides, 2 place Jussieu, 75251 Paris Cedex 05, France
| | - C Caroli
- Groupe de Physique des Solides, 2 place Jussieu, 75251 Paris Cedex 05, France
| | - T Baumberger
- Groupe de Physique des Solides, 2 place Jussieu, 75251 Paris Cedex 05, France
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Abstract
We present an extensive experimental study and scaling analysis of friction of gelatin gels on glass. At low driving velocities, sliding occurs via propagation of periodic self-healing slip pulses whose velocity is limited by collective diffusion of the gel network. Healing can be attributed to a frictional instability occurring at the slip velocity V=Vc. For V>Vc, sliding is homogeneous and friction is ruled by the shear-thinning rheology of an interfacial layer of thickness of order the (nanometric) mesh size, containing a solution of polymer chain ends hanging from the network. In spite of its high degree of confinement, the rheology of this system does not differ qualitatively from known bulk ones. The observed ageing of the static friction threshold reveals the slow increase of adhesive bonding between chain ends and glass. Such structural ageing is compatible with the existence of a velocity-weakening regime at velocities smaller than Vc, hence with the existence of the healing instability.
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Affiliation(s)
- T Baumberger
- Groupe de Physique des Solides, 2 place Jussieu, 75251 Paris, Cedex 05, France
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Abstract
We study the low-velocity (0.1-100 microm s(-1)) frictional properties of interfaces between a rough glassy polymer and smooth silanized glass, a configuration which gives direct access to the rheology of the adhesive joints in which shear localizes. We show that these joints exhibit the full phenomenology expected for confined quasi-2D soft glasses: they strengthen logarithmically when aging at rest, and weaken (rejuvenate) when sliding. Rejuvenation is found to saturate at large velocities. Moreover, aging at rest is shown to be strongly accelerated when waiting under finite stress below the static threshold.
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Affiliation(s)
- L Bureau
- Groupe de Physique des Solides (UMR 7588), Universités Paris 6 & 7, 2 place Jussieu, 75251 Paris Cedex 05, France.
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Velický B, Caroli C. Pressure dependence of the sound velocity in a two-dimensional lattice of Hertz-Mindlin balls: mean-field description. Phys Rev E Stat Nonlin Soft Matter Phys 2002; 65:021307. [PMID: 11863516 DOI: 10.1103/physreve.65.021307] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/25/2001] [Indexed: 05/23/2023]
Abstract
We study the dependence on the external pressure P of the velocities v(L,T) of long wavelength sound waves in a confined two-dimensional hexagonal close-packed lattice of 3D elastic frictional balls interacting via one-sided Hertz-Mindlin contact forces, whose diameters exhibit mild dispersion. The presence of an underlying long range order enables us to build an effective medium description, which incorporates the radial fluctuations of the contact forces acting on a single site. Due to the nonlinearity of Hertz elasticity, self-consistency results in a highly nonlinear differential equation for the "equation of state" linking the effective stiffness of the array with the applied pressure, from which sound velocities are then obtained. The results are in excellent agreement with existing experimental results and simulations in the high- and intermediate-pressure regimes. It emerges from the analysis that the departure of v(L)(P) from the ideal P(1/6) Hertz behavior must be attributed primarily to the fluctuations of the stress field, rather than to the pressure dependence of the number of contacts.
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Affiliation(s)
- B Velický
- Groupe de Physique des Solides, 2 place Jussieu, 75251 Paris Cedex 05, France
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Krieg R, Devos J, Caroli C, Solomos G, Ennis P, Kalkhof D. On the prediction of the reactor vessel integrity under severe accident loadings (RPVSA). Nuclear Engineering and Design 2001. [DOI: 10.1016/s0029-5493(01)00394-6] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
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Bureau L, Baumberger T, Caroli C. Jamming creep of a frictional interface. Phys Rev E Stat Nonlin Soft Matter Phys 2001; 64:031502. [PMID: 11580337 DOI: 10.1103/physreve.64.031502] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/24/2001] [Indexed: 05/23/2023]
Abstract
We measure the displacement response of a frictional multicontact interface between identical polymer glasses to a biased shear force oscillation. We evidence the existence, for maximum forces close below the nominal static threshold, of a jamming creep regime governed by an aging-rejuvenation competition acting within the micrometer-sized contacting asperities. The time dependence of the creep process deviates from the standard Rice-Ruina [J. R. Rice and A. L. Ruina, J. Appl. Mech. 50, 343 (1983)] phenomenology at early times; this suggests the possibility of an aging-rejuvenation competition at much smaller scales, within the nanometer-thick adhesive junctions.
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Affiliation(s)
- L Bureau
- Groupe de Physique des Solides, Universités Paris 6 et 7, UMR CNRS 7588, 2 place Jussieu, 75251 Paris, Cedex 05, France
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Caroli C, Combescot R, Nozieres P, Saint-James D. A direct calculation of the tunnelling current: IV. Electron-phonon interaction effects. ACTA ACUST UNITED AC 2001. [DOI: 10.1088/0022-3719/5/1/006] [Citation(s) in RCA: 276] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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Caroli C, Combescot R, Lederer D, Nozieres P, Saint-James D. A direct calculation of the tunnelling current. II. Free electron description. ACTA ACUST UNITED AC 2001. [DOI: 10.1088/0022-3719/4/16/025] [Citation(s) in RCA: 136] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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Bureau L, Baumberger T, Caroli C. Shear response of a frictional interface to a normal load modulation. Phys Rev E Stat Phys Plasmas Fluids Relat Interdiscip Topics 2000; 62:6810-6820. [PMID: 11102034 DOI: 10.1103/physreve.62.6810] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/30/2000] [Indexed: 05/23/2023]
Abstract
We study the shear response of a sliding multicontact interface submitted to a harmonically modulated normal load, without loss of contact. We measure, at low velocities (V<100 &mgr;m s(-1)), the average value &Fmacr; of the friction force and the amplitude of its first and second harmonic components. The excitation frequency (f=120 Hz) is chosen much larger than the natural one, associated with the dynamical aging of the interface. We show the following: (i) In agreement with the engineering thumb rule, even a modest modulation induces a substantial decrease of &Fmacr;. (ii) The Rice-Ruina state and rate model, though appropriate to describe the slow frictional dynamics, must be extended when dealing with our "high" frequency regime. That is, the rheology which controls the shear strength must explicitly account not only for the plastic response of the adhesive junctions between load-bearing asperities, but also for the elastic contribution of the asperities bodies. This "elastoplastic" friction model leads to predictions in excellent quantitative agreement with all our experimental data.
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Affiliation(s)
- L Bureau
- Groupe de Physique des Solides, 2 place Jussieu, 75251 Paris Cedex 05, France
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Caroli C. Slip pulses at a sheared frictional viscoelastic/nondeformable interface. Phys Rev E Stat Phys Plasmas Fluids Relat Interdiscip Topics 2000; 62:1729-37. [PMID: 11088634 DOI: 10.1103/physreve.62.1729] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/23/2000] [Indexed: 11/07/2022]
Abstract
We study the possibility for a semi-infinite block of linear viscoelastic material, in homogeneous frictional contact with a nondeformable one, to slide under shear via a periodic set of "self-healing pulses," i.e., a set of drifting slip regions separated by stick ones. We show that, contrary to existing experimental indications, such a mode of frictional sliding is impossible for an interface obeying a simple local Coulomb law of solid friction. We then discuss possible physical improvements of the friction model which might open the possibility of such dynamics, among which slip weakening of the friction coefficient, and stress the interest of developing systematic experimental investigations of this question.
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Affiliation(s)
- C Caroli
- Groupe de Physique des Solides,* 2 Place Jussieu, 75251 Paris Cedex 05, France
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Langes K, Nienaber CA, Caroli C, Volk C, Koschyk DH, Hofmann T, Meinertz T. [Diastolic left ventricular dysfunction with microvascular angina (Syndrome X)]. Z Kardiol 1996; 85:16-9. [PMID: 8717143] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
Findings on left ventricular function in microvascular angina (syndrome X) are somewhat controversial. Recently, an increased prevalence of insulin resistance and hyperlipoproteinemia has been demonstrated as well as arterial hypertension potentially impairing the left ventricular diastolic function. In an attempt to analyze the diastolic function at rest, we investigated by Doppler echocardiography the transmitral blood flow in 16 patients (51 +/- 8 years). The diastolic data were compared with those of 12 healthy people (50 +/- 6 years) who were matched for age. The patients with microvascular angina revealed a slightly higher systolic blood pressure (134 +/- 18 mm Hg vs 125 +/- 9 mm Hg, n.s.), but imposed by higher left ventricular mass index (92 +/- 18 g/m2 vs 65 +/- 13 g/m2, p < 0.001). There was a trend to an elevated A-wave-peak during transmitral blood flow (61 +/- 14 cm/s vs 50 +/- 9 cm/s). The findings suggest impairment of the left ventricular relaxation before manifestation of left ventricular hypertrophy and hypertension takes place.
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Affiliation(s)
- K Langes
- Abteilung fur Kardiologie, Medizinische Klinik und Poliklinik, Universitats-Krankenhaus Eppendorf, Hamburg
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Baumberger T, Caroli C, Perrin B, Ronsin O. Nonlinear analysis of the stick-slip bifurcation in the creep-controlled regime of dry friction. Phys Rev E Stat Phys Plasmas Fluids Relat Interdiscip Topics 1995; 51:4005-4010. [PMID: 9963111 DOI: 10.1103/physreve.51.4005] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
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Heslot F, Baumberger T, Perrin B, Caroli B, Caroli C. Creep, stick-slip, and dry-friction dynamics: Experiments and a heuristic model. Phys Rev E Stat Phys Plasmas Fluids Relat Interdiscip Topics 1994; 49:4973-4988. [PMID: 9961818 DOI: 10.1103/physreve.49.4973] [Citation(s) in RCA: 100] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/28/2023]
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Berréhar J, Caroli C, Lapersonne-Meyer C, Schott M. Surface patterns on single-crystal films under uniaxial stress: Experimental evidence for the Grinfeld instability. Phys Rev B Condens Matter 1992; 46:13487-13495. [PMID: 10003396 DOI: 10.1103/physrevb.46.13487] [Citation(s) in RCA: 25] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/12/2023]
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Abou Said S, Caira M, Caroli C, Violante V. Finite element analysis with an axisymmetric model of the tritium diffusion in a ceramic blanket solution of a commercial tokamak. Fusion Engineering and Design 1991. [DOI: 10.1016/0920-3796(91)90224-e] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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Caroli B, Caroli C, Roulet B, Voorhees P. Effect of elastic stresses on the morphological stability of a solid sphere growing from a supersaturated melt. ACTA ACUST UNITED AC 1989. [DOI: 10.1016/0001-6160(89)90284-8] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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Caroli B, Caroli C, Roulet B, Langer JS. Solvability condition for needle crystals at large undercooling in a nonlocal model of solidification. Phys Rev A Gen Phys 1986; 33:442-452. [PMID: 9896629 DOI: 10.1103/physreva.33.442] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/11/2023]
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Caroli B, Caroli C, Misbah C, Roulet B. Solutal convection and morphological instability in directional solidification of binary alloys. ACTA ACUST UNITED AC 1985. [DOI: 10.1051/jphys:01985004603040100] [Citation(s) in RCA: 40] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022]
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Caroli B, Caroli C, Misbah C, Roulet B. Solutal convection and morphological instability in directional solidification of binary alloys. - II. Effect of the density difference between the two phases. ACTA ACUST UNITED AC 1985. [DOI: 10.1051/jphys:0198500460100165700] [Citation(s) in RCA: 26] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022]
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Shukla S, Blotta I, Masella R, Caroli C, Delle Femmine P. Antitumour activity of lanthanum. Inorganica Chim Acta 1984. [DOI: 10.1016/s0020-1693(00)94607-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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Solo AJ, Caroli C, Darby MV, McKay T, Slaunwhite WD, Hebborn P. 7 alpha-Alkyltestosterone derivatives: synthesis and activity as androgens and as aromatase inhibitors. Steroids 1982; 40:603-14. [PMID: 7187711 DOI: 10.1016/0039-128x(82)90001-0] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Abstract
The 7 alpha-ethyl,propyl,butyl,3'-t-butoxypropyl,allyl,3'-hydroxypropyl 17-acetate, and 3'-chloropropyl 17-acetate derivatives of testosterone and the 7 alpha-3'-t-butoxypropyl, 3'-hydroxypropyl,3'-acetoxypropyl,3'-bromoacetoxypropyl, 3'-chloropropyl, and 2'-oxo-3'-bromopropyl derivatives of 4-androstene-3,17-dione were synthesized. The testosterone derivatives were found to lose androgenic and anabolic activity rapidly as the size of the group at the 7 position increased. Many of the compounds were tested as inhibitors of aromatase. The 17-keto compounds were more active than the corresponding alcohols and the enzyme was found to tolerate at least the bulk of a hydroxypropyl group at the C-7 alpha position.
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Caroli B, Caroli C, Roulet B. On the emergence of one-dimensional front instabilities in directional solidification and fusion of binary mixtures. ACTA ACUST UNITED AC 1982. [DOI: 10.1051/jphys:0198200430120176700] [Citation(s) in RCA: 111] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022]
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