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Marder M, Eftekhari B, Patzek TW. Solvable model of gas production decline from hydrofractured networks. Phys Rev E 2021; 104:065001. [PMID: 35030847 DOI: 10.1103/physreve.104.065001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2021] [Accepted: 11/17/2021] [Indexed: 06/14/2023]
Abstract
We address questions that arose from studying gas and oil production from hydrofractured wells. Does past production predict the future? This depends on deducing from production as much as possible about the plausible geometries of the fracture network. We address the problem through a solvable model and use kinetic Monte Carlo and Green's function techniques to solve it. We have three main findings. First, at sufficiently long times, the production from all compact fracture networks is described by a universal function with two scaling parameters, one of which is the diffusivity of unbroken rock α and the second of which is a parameter V_{ext} with units of volume. Second, for fracture networks where the power-law distribution of fracture spacings falls below a critical value (and this appears to be the case in practice), early-time production always scales as one over the square root of time. Third, the diffusivity α that sets the scale for late-time production is inherently difficult to estimate from production data, but the methods here provide the best hope of obtaining it and thus can determine the physics that will govern the decline of unconventional gas and oil wells.
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Affiliation(s)
- M Marder
- Department of Physics, The University of Texas at Austin, Austin, Texas 78712, USA
| | - Behzad Eftekhari
- Enthought Energy Solutions, 1502 Sawyer Street, Suite 232 Houston, Texas 77007, USA
| | - Tadeusz W Patzek
- Petroleum Engineering Research Center, King Abdullah University of Science and Technology, Thuwal 23955, Saudi Arabia
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Marder M. Slepyan's dynamic contribution to studies of fracture. Philos Trans A Math Phys Eng Sci 2019; 377:20190098. [PMID: 31474202 DOI: 10.1098/rsta.2019.0098] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Accepted: 04/30/2019] [Indexed: 06/10/2023]
Abstract
After a brief review of atomistic theories of defect dynamics in solids, a summary of Slepyan's first computation of dynamic fracture in a lattice is presented. Some of the main extensions and clarifi- cations of the original physical picture are then summarized. Many molecular dynamics simulations of fracture would benefit if Slepyan's work were better known. This article is part of the theme issue 'Modelling of dynamic phenomena and localization in structured media (part 1)'.
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Affiliation(s)
- M Marder
- Department of Physics, and Center for Nonlinear Dynamics, The University of Texas at Austin, Austin 78712, TX, USA
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Ontiveros M, Rinaldi D, Marder M, Espelt MV, Mangialavori I, Vigil M, Rossi JP, Ferreira-Gomes M. Natural flavonoids inhibit the plasma membrane Ca 2+-ATPase. Biochem Pharmacol 2019; 166:1-11. [PMID: 31071329 DOI: 10.1016/j.bcp.2019.05.004] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2019] [Accepted: 05/03/2019] [Indexed: 11/25/2022]
Abstract
Research on flavonoids from plant sources has recently sparked increasing interest because of their beneficial health properties. Different studies have shown that flavonoids change the intracellular Ca2+ homeostasis linked to alterations in the function of mitochondria, Ca2+ channels and Ca2+ pumps. These findings hint at plasma membrane Ca2+-ATPase (PMCA) involvement, as it transports Ca2+ actively to the extracellular medium coupled to ATP hydrolysis, thus maintaining ion cellular homeostasis. The present study aims to investigate the effect of several natural flavonoids on PMCA both in isolated protein systems and in living cells, and to establish the relationship between flavonoid structure and inhibitory activity on PMCA. Our results show that natural flavonoids inhibited purified and membranous PMCA with different effectiveness: quercetin and gossypin were the most potent and their inhibition mechanisms seem to be different, as quercetin does not prevent ATP binding whereas gossypin does. Moreover, PMCA activity was inhibited in human embryonic kidney cells which transiently overexpress PMCA, suggesting that the effects observed on isolated systems could occur in a complex structure like a living cell. In conclusion, this work reveals a novel molecular mechanism through which flavonoids inhibit PMCA, which leads to Ca2+ homeostasis and signaling alterations in the cell.
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Affiliation(s)
- M Ontiveros
- IQUIFIB - Instituto de Química y Fisicoquímica Biológicas, Conicet/UBA, Junín 956 (1113) Buenos Aires, Argentina
| | - D Rinaldi
- IQUIFIB - Instituto de Química y Fisicoquímica Biológicas, Conicet/UBA, Junín 956 (1113) Buenos Aires, Argentina
| | - M Marder
- IQUIFIB - Instituto de Química y Fisicoquímica Biológicas, Conicet/UBA, Junín 956 (1113) Buenos Aires, Argentina
| | - M V Espelt
- IQUIFIB - Instituto de Química y Fisicoquímica Biológicas, Conicet/UBA, Junín 956 (1113) Buenos Aires, Argentina
| | - I Mangialavori
- IQUIFIB - Instituto de Química y Fisicoquímica Biológicas, Conicet/UBA, Junín 956 (1113) Buenos Aires, Argentina
| | - M Vigil
- IQUIFIB - Instituto de Química y Fisicoquímica Biológicas, Conicet/UBA, Junín 956 (1113) Buenos Aires, Argentina
| | - J P Rossi
- IQUIFIB - Instituto de Química y Fisicoquímica Biológicas, Conicet/UBA, Junín 956 (1113) Buenos Aires, Argentina.
| | - M Ferreira-Gomes
- IQUIFIB - Instituto de Química y Fisicoquímica Biológicas, Conicet/UBA, Junín 956 (1113) Buenos Aires, Argentina.
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Marder M, Eftekhari B, Patzek TW. Solvable Model for Dynamic Mass Transport in Disordered Geophysical Media. Phys Rev Lett 2018; 120:138302. [PMID: 29694205 DOI: 10.1103/physrevlett.120.138302] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/26/2017] [Revised: 01/31/2018] [Indexed: 06/08/2023]
Abstract
We present an analytically solvable model for transport in geophysical materials on large length and time scales. It describes the flow of gas to a complicated absorbing boundary over long periods of time. We find a solution to this model using Green's function techniques, and apply the solution to three absorbing networks of increasing complexity.
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Affiliation(s)
- M Marder
- Department of Physics, The University of Texas at Austin, Austin, Texas 78712, USA
| | - Behzad Eftekhari
- Department of Physics, The University of Texas at Austin, Austin, Texas 78712, USA
| | - Tadeusz W Patzek
- Petroleum Engineering Research Center, King Abdullah University of Science and Technology, Thuwal 23955, Saudi Arabia
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Volmer M, Marder M. Zur Theorie der linearen Kristallisationsgeschwindigkeit unterkühlter Schmelzen und unterkühlter fester Modifikationen. ACTA ACUST UNITED AC 2017. [DOI: 10.1515/zpch-1931-15405] [Citation(s) in RCA: 56] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
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Abstract
Hydrofracturing to recover natural gas and oil relies on the creation of a fracture network with pressurized water. We analyze the creation of the network in two ways. First, we assemble a collection of analytical estimates for pressure-driven crack motion in simple geometries, including crack speed as a function of length, energy dissipated by fluid viscosity and used to break rock, and the conditions under which a second crack will initiate while a first is running. We develop a pseudo-three-dimensional numerical model that couples fluid motion with solid mechanics and can generate branching crack structures not specified in advance. One of our main conclusions is that the typical spacing between fractures must be on the order of a meter, and this conclusion arises in two separate ways. First, it arises from analysis of gas production rates, given the diffusion constants for gas in the rock. Second, it arises from the number of fractures that should be generated given the scale of the affected region and the amounts of water pumped into the rock.
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Affiliation(s)
- M Marder
- Department of Physics, The University of Texas at Austin, Austin, Texas 78712, USA
| | - Chih-Hung Chen
- Department of Physics, The University of Texas at Austin, Austin, Texas 78712, USA
| | - T Patzek
- Earth Sciences and Engineering Division, Upstream Petroleum Engineering Research Center, King Abdullah University of Science and Technology, Thuwal 23955-6900, Kingdom of Saudi Arabia
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Behn C, Marder M. The transition from subsonic to supersonic cracks. Philos Trans A Math Phys Eng Sci 2015; 373:20140122. [PMID: 25713443 PMCID: PMC4342976 DOI: 10.1098/rsta.2014.0122] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
We present the full analytical solution for steady-state in-plane crack motion in a brittle triangular lattice. This allows quick numerical evaluation of solutions for very large systems, facilitating comparisons with continuum fracture theory. Cracks that propagate faster than the Rayleigh wave speed have been thought to be forbidden in the continuum theory, but clearly exist in lattice systems. Using our analytical methods, we examine in detail the motion of atoms around a crack tip as crack speed changes from subsonic to supersonic. Subsonic cracks feature displacement fields consistent with a stress intensity factor. For supersonic cracks, the stress intensity factor disappears. Subsonic cracks are characterized by small-amplitude, high-frequency oscillations in the vertical displacement of an atom along the crack line, while supersonic cracks have large-amplitude, low-frequency oscillations. Thus, while supersonic cracks are no less physical than subsonic cracks, the connection between microscopic and macroscopic behaviour must be made in a different way. This is one reason supersonic cracks in tension had been thought not to exist.
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Affiliation(s)
- Chris Behn
- Center for Nonlinear Dynamics and Department of Physics, The University of Texas at Austin, Austin, TX, USA
| | - M Marder
- Center for Nonlinear Dynamics and Department of Physics, The University of Texas at Austin, Austin, TX, USA
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Abstract
We examine the fracture mechanics of tearing graphene. We present a molecular dynamics simulation of the propagation of cracks in clamped, free-standing graphene as a function of the out-of-plane force. The geometry is motivated by experimental configurations that expose graphene sheets to out-of-plane forces, such as back-gate voltage. We establish the geometry and basic energetics of failure and obtain approximate analytical expressions for critical crack lengths and forces. We also propose a method to obtain graphene's toughness. We observe that the cracks' path and the edge structure produced are dependent on the initial crack length. This work may help avoid the tearing of graphene sheets and aid the production of samples with specific edge structures.
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Affiliation(s)
- M J B Moura
- IBM Research-Brazil, Av. Pasteur 138/146, Botafogo, Rio de Janeiro, CEP 22290-240, Brazil
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King B, Stone M, Zhang HP, Gerkema T, Marder M, Scott RB, Swinney HL. Buoyancy frequency profiles and internal semidiurnal tide turning depths in the oceans. ACTA ACUST UNITED AC 2012. [DOI: 10.1029/2011jc007681] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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Millet V, Marder M, Pasquini L. Adult CNP::EGFP transgenic mouse shows pronounced hypomyelination and an increased vulnerability to cuprizone-induced demyelination. Exp Neurol 2012; 233:490-504. [DOI: 10.1016/j.expneurol.2011.11.028] [Citation(s) in RCA: 6] [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] [Received: 07/18/2011] [Revised: 10/17/2011] [Accepted: 11/21/2011] [Indexed: 12/20/2022]
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Pasquini LA, Millet V, Hoyos HC, Giannoni JP, Croci DO, Marder M, Liu FT, Rabinovich GA, Pasquini JM. Galectin-3 drives oligodendrocyte differentiation to control myelin integrity and function. Cell Death Differ 2011; 18:1746-56. [PMID: 21566659 DOI: 10.1038/cdd.2011.40] [Citation(s) in RCA: 112] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
Galectins control critical pathophysiological processes, including the progression and resolution of central nervous system (CNS) inflammation. In spite of considerable progress in dissecting their role within lymphoid organs, their functions within the inflamed CNS remain elusive. Here, we investigated the role of galectin-glycan interactions in the control of oligodendrocyte (OLG) differentiation, myelin integrity and function. Both galectin-1 and -3 were abundant in astrocytes and microglia. Although galectin-1 was abundant in immature but not in differentiated OLGs, galectin-3 was upregulated during OLG differentiation. Biochemical analysis revealed increased activity of metalloproteinases responsible for cleaving galectin-3 during OLG differentiation and modulating its biological activity. Exposure to galectin-3 promoted OLG differentiation in a dose- and carbohydrate-dependent fashion consistent with the 'glycosylation signature' of immature versus differentiated OLG. Accordingly, conditioned media from galectin-3-expressing, but not galectin-3-deficient (Lgals3(-/-)) microglia, successfully promoted OLG differentiation. Supporting these findings, morphometric analysis showed a significant decrease in the frequency of myelinated axons, myelin turns (lamellae) and g-ratio in the corpus callosum and striatum of Lgals3(-/-) compared with wild-type (WT) mice. Moreover, the myelin structure was loosely wrapped around the axons and less smooth in Lgals3(-/-) mice versus WT mice. Behavior analysis revealed decreased anxiety in Lgals3(-/-) mice similar to that observed during early demyelination induced by cuprizone intoxication. Finally, commitment toward the oligodendroglial fate was favored in neurospheres isolated from WT but not Lgals3(-/-) mice. Hence, glial-derived galectin-3, but not galectin-1, promotes OLG differentiation, thus contributing to myelin integrity and function with critical implications in the recovery of inflammatory demyelinating disorders.
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Affiliation(s)
- L A Pasquini
- Department of Biological Chemistry, IQUIFIB, FFyB, UBA-CONICET, Bs As, Argentina
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Zhang HP, Niemczura J, Dennis G, Ravi-Chandar K, Marder M. Toughening effect of strain-induced crystallites in natural rubber. Phys Rev Lett 2009; 102:245503. [PMID: 19659026 DOI: 10.1103/physrevlett.102.245503] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/22/2009] [Indexed: 05/28/2023]
Abstract
We study fracture propagation in stretched natural rubber sheets. Experimental results in specimens stretched less than 3.8 times show a monotonic increase in the crack speed with stretch and can be explained by a numerical model based on neo-Hookean theory and Kelvin dissipation. In specimens stretched more than 3.8 times, strain-induced crystallites act as reinforcing and toughening fillers and significantly increase fracture resistance, like nanostructures in other polymeric or biological materials. Consequently, as we increase the amount of stretch, fractures travel slower and slower, and eventually halt altogether.
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Affiliation(s)
- H P Zhang
- Center for Nonlinear Dynamics and Department of Physics, The University of Texas at Austin, Austin, Texas 78712, USA
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Marder M. Dynamics of epidemics on random networks. Phys Rev E Stat Nonlin Soft Matter Phys 2007; 75:066103. [PMID: 17677321 DOI: 10.1103/physreve.75.066103] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/09/2006] [Revised: 01/16/2007] [Indexed: 05/16/2023]
Abstract
This paper examines how diseases on random networks spread in time. The disease is described by a probability distribution function for the number of infected and recovered individuals, and the probability distribution is described by a generating function. The time development of the disease is obtained by iterating the generating function. In cases where the disease can expand to an epidemic, the probability distribution function is the sum of two parts; one that is static at long times, and another whose mean grows exponentially. The time development of the mean number of infected individuals is obtained analytically. When epidemics occur, the probability distributions are very broad, and the uncertainty in the number of infected individuals at any given time is typically larger than the mean number of infected individuals.
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Affiliation(s)
- M Marder
- Center for Nonlinear Dynamics and Department of Physics, The University of Texas at Austin, Austin, Texas 78712, USA.
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Hellión-Ibarrola MC, Ibarrola DA, Montalbetti Y, Kennedy ML, Heinichen O, Campuzano M, Tortoriello J, Fernández S, Wasowski C, Marder M, De Lima TCM, Mora S. The anxiolytic-like effects of Aloysia polystachya (Griseb.) Moldenke (Verbenaceae) in mice. J Ethnopharmacol 2006; 105:400-8. [PMID: 16386395 DOI: 10.1016/j.jep.2005.11.013] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/24/2005] [Revised: 09/16/2005] [Accepted: 11/18/2005] [Indexed: 05/05/2023]
Abstract
The aim of the present work is to demonstrate the putative sedative and anxiolytic-like effects of a hydro-ethanolic extract obtained from the aerial parts of Aloysia polystachya (Verbenaceae) in male mice using several behavioural assays. Groups of male mice orally treated with doses of 1.0, 10.0 and 100.0 mg/kg of the extract did not show any significant alteration of their locomotor activity, body temperature or motor coordination. The same treatment increased the duration of the sleeping time induced by 30.0 mg/kg i.p. of sodium pentobarbital. However, the sleeping time induced by ethyl ether was not modified by the oral administration of the extract, not confirming the putative sedative effect of the plant. The ethanolic extract also significantly increased the percentage of both entries (1.0 and 100.0 mg/kg) and the time spent (10.0 and 100.0 mg/kg) into the open arms of the elevated plus maze (EPM). Nevertheless, the binding of (3)H-flunitrazepam ((3)H-FNZ) to the benzodiazepine binding site (BDZ-bs), in washed crude synaptosomal membranes from rat cerebral cortex, was not affected by the semi-purified components from Aloysia polystachya. These results indicate an anxiolytic-like profile of action for the extract of Aloysia polystachya without sedative side effect, being this activity probably mediated by other mechanism than BDZ-bs modulation at the GABA(A) receptors.
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Affiliation(s)
- M C Hellión-Ibarrola
- Laboratory of Psychopharmacology, Department of Pharmacology, Facultad de Ciencias Químicas, Universidad Nacional de Asunción, Campus Universitario, P.O. Box 1055, San Lorenzo, Paraguay.
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Abstract
This Letter presents a theory for the rupture of rubber. Unlike conventional cracks, ruptures in rubber travel faster than the speed of sound and consist of two oblique shocks that meet at a point. Physical features of rubber needed for this phenomenon include Kelvin dissipation and an increase of toughness as rubber retracts. There are three levels of theoretical description: an approximate continuum theory, an exact analytical solution of a slightly simplified discrete problem, and numerical solution of realistic and fully nonlinear equations of motion.
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Affiliation(s)
- M Marder
- Center for Nonlinear Dynamics and Department of Physics, The University of Texas at Austin, Austin, Texas 78712, USA
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Deegan RD, Chheda S, Patel L, Marder M, Swinney HL, Kim J, de Lozanne A. Wavy and rough cracks in silicon. Phys Rev E Stat Nonlin Soft Matter Phys 2003; 67:066209. [PMID: 16241328 DOI: 10.1103/physreve.67.066209] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/19/2002] [Indexed: 05/04/2023]
Abstract
Single-crystal silicon exhibits a strong preference to cleave along a few certain planes, but in experiments we observe wavy cracks with almost no evidence of a preferred fracture direction. Furthermore, we find that the fracture surface is an anisotropic and self-affine fractal over five decades in length scale in the direction of the crack with a roughness exponent of 0.78. In our experiments a 1-4 cm wide strip of single-crystal silicon is heated to 378 degrees C and lowered into a 20 degrees C water bath at speeds of 0.2-5 cm/s. The thermal gradient produces cracks that, depending on the speed, are straight, wavy with amplitude 0.1-0.5 cm and wavelength 0.3-1 cm, or multibranched. The transition from one mode of fracture to another is discontinuous and hysteretic.
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Affiliation(s)
- Robert D Deegan
- Center for Nonlinear Dynamics, Department of Physics, The University of Texas, Austin, Texas 78712, USA
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Abstract
We have found an oscillating instability of fast-running cracks in thin rubber sheets. A well defined transition from straight to wavy cracks occurs as the amount of biaxial strain increases. Measurements of the amplitude and wavelength of the oscillation near the onset of this instability indicate that the instability is a Hopf bifurcation.
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Affiliation(s)
- Robert D Deegan
- Center for Nonlinear Dynamics and Department of Physics, The University of Texas at Austin, Austin, TX 78712, USA.
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Abstract
Consider a block placed on a table and pushed sideways until it begins to slide. Amontons and Coulomb found that the force required to initiate sliding is proportional to the weight of the block (the constant of proportionality being the static coefficient of friction), but independent of the area of contact. This is commonly explained by asserting that, owing to the presence of asperities on the two surfaces, the actual area in physical contact is much smaller than it seems, and grows in proportion to the applied compressive force. Here we present an alternative picture of the static friction coefficient, which starts with an atomic description of surfaces in contact and then employs a multiscale analysis technique to describe how sliding occurs for large objects. We demonstrate the existence of self-healing cracks that have been postulated to solve geophysical paradoxes about heat generated by earthquakes, and we show that, when such cracks are present at the atomic scale, they result in solids that slip in accord with Coulomb's law of friction. We expect that this mechanism for friction will be found to operate at many length scales, and that our approach for connecting atomic and continuum descriptions will enable more realistic first-principles calculations of friction coefficients.
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Affiliation(s)
- E Gerde
- Computational and Applied Mathematics and Center for Nonlinear Dynamics, The University of Texas at Austin, Austin, Texas 78712, USA
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Marder M, Estiú G, Blanch LB, Viola H, Wasowski C, Medina JH, Paladini AC. Molecular modeling and QSAR analysis of the interaction of flavone derivatives with the benzodiazepine binding site of the GABA(A) receptor complex. Bioorg Med Chem 2001; 9:323-35. [PMID: 11249125 DOI: 10.1016/s0968-0896(00)00250-9] [Citation(s) in RCA: 67] [Impact Index Per Article: 2.9] [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: 10/27/2022]
Abstract
A large number of structurally different classes of ligands, many of them sharing the main characteristics of the benzodiazepine (BDZ) nucleus, are active in the modulation of anxiety, sedation, convulsion, myorelaxation, hypnotic and amnesic states in mammals. These compounds have high affinity for the benzodiazepine binding site (BDZ-bs) of the GABA(A) receptor complex. Since 1989 onwards our laboratories established that some natural flavonoids were ligands for the BDZ-bs which exhibit medium to high affinity in vitro and anxiolytic activity in vivo. Further research resulted in the production of synthetic flavonoid derivatives with increased biochemical and pharmacological activities. The currently accepted receptor/pharmacophore model of the BDZ-bs (Zhang, W.; Koeler, K. F.; Zhang, P.; Cook, J. M. Drug Des. Dev. 1995, 12, 193) accounts for the general requirements that should be met by this receptor for ligand recognition. In this paper we present a model pharmacophore which defines the characteristics for a ligand to be able to interact and bind to a flavone site, in the GABA(A) receptor. closely related to the BDZ-bs. A model of a flavone binding site has already been described (Dekermendjian, K.; Kahnberg, P.; Witt, M. R.; Sterner, O.; Nielsen, M.; Liljerfors, T. J. Med. Chem. 1999, 42, 4343). However, this alternative model is based only on graphic superposition techniques using as template a non-BDZ agonist. In this investigation all the natural and synthetic flavonoids found to be ligands for the BDZ-bs have been compared with the classical BDZ diazepam. A QSAR regression analysis of the parameters that describe the interaction demonstrates the relevance of the electronic effects for the ligand binding, and shows that they are associated with the negatively charged oxygen atom of the carbonyl group of the flavonoids and with the nature of the substituent in position 3'.
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Affiliation(s)
- M Marder
- Instituto de Química y Fisicoquímica Biológicas, Faultad de Farmacia y Bioquímica, Buenos Aires, Argentina
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Franklin SV, Mertens F, Marder M. Portevin-Le chatelier effect. Phys Rev E Stat Phys Plasmas Fluids Relat Interdiscip Topics 2000; 62:8195-8206. [PMID: 11138118 DOI: 10.1103/physreve.62.8195] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/29/1999] [Indexed: 05/23/2023]
Abstract
Aluminum subjected to smooth mechanical loading does not often deform in a correspondingly smooth manner. Typically it deforms inhomogeneously through the propagation of deformation fronts that slowly traverse the sample. These are called Portevin-Le Chatelier fronts; what determines their velocity has been somewhat mysterious. We present a phenomenological theory for deformation fronts that centers on a nonlocal rate dependence of the flow stress. In a one-dimensional idealization the equations can be solved exactly, and compared directly with experiment. Many significant features of deformation fronts are captured, including a well-known transition from hopping to continuous front motion. The phenomenology's predictions are confirmed by our experiments.
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Affiliation(s)
- SV Franklin
- Center for Nonlinear Dynamics and Department of Physics, The University of Texas at Austin, Austin, Texas 78712, USA
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Viola H, Marder M, Wasowski C, Giorgi O, Paladini AC, Medina JH. 6,3'-dibromoflavone and 6-nitro-3'-bromoflavone: new additions to the 6,3'-disubstituted flavone family of high-affinity ligands of the brain benzodiazepine binding site with agonistic properties. Biochem Biophys Res Commun 2000; 273:694-8. [PMID: 10873666 DOI: 10.1006/bbrc.2000.2979] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.6] [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: 11/22/2022]
Abstract
6,3'-dibromoflavone and 6-nitro-3'-bromoflavone inhibited [(3)H]flunitrazepam binding to the benzodiazepine binding site of the gamma amino butyric acid receptor complex with K(i) values between 17 and 36 nM in different brain regions. Their gamma amino butyric acid ratio for [(3)H]flunitrazepam binding to cerebral cortex membranes indicated partial agonistic properties. Both compounds had similar pharmacological effects: they produced anxiolytic-like effects at low doses but did not alter locomotor activity or muscle tonicity; sedation was caused only at doses higher than 30 mg/kg in mice. These synthetic flavone derivatives join an existing family of 6,3'-disubstituted flavone compounds with high affinity for the benzodiazepine binding site and partial agonistic profiles.
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Affiliation(s)
- H Viola
- Facultad de Medicina, Instituto de Biología Celular y Neurociencias, Paraguay 2155, Buenos Aires, (1121), Argentina
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Viola H, Wolfman C, Marder M, Goutman JD, Bianchin M, Wasowski C, Calvo DJ, Izquierdo I, Paladini AC, Medina JH. 6-Chloro-3'-nitroflavone is a potent ligand for the benzodiazepine binding site of the GABA(A) receptor devoid of intrinsic activity. Pharmacol Biochem Behav 2000; 65:313-20. [PMID: 10672984 DOI: 10.1016/s0091-3057(99)00199-9] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
6-Chloro-3'-nitroflavone integrates a list of nearly 70 flavone derivatives synthesized in our laboratories. The effects of 6-chloro-3'-nitroflavone on the benzodiazepine binding sites (BDZ-BSs) of the GABA(A) receptor were examined in vitro and in vivo. 6-Chloro-3'-nitroflavone inhibited the [3H]flunitrazepam ([3H]FNZ) binding to rat cerebral cortex membranes with a Ki of 6.68 nM and the addition of GABA to extensively washed membranes did not modify its affinity for the BDZ-BSs (GABA-shift = 1.16+/-0.12). The binding assays performed in rat striatal and cerebellar brain membranes showed that this compound has similar affinity to different populations of BDZ-BSs. Electrophysiological experiments revealed that 6-chloro-3'-nitroflavone did not affect GABA(A)-receptors (GABA(A)-Rs) responses recorded in Xenopus oocytes expressing alpha1beta2gamma2s subunits, but blocked the potentiation exerted by diazepam (DZ) on GABA-activated chloride currents. In vivo experiments showed that 6-chloro-3'-nitroflavone did not possess anxiolytic, anticonvulsant, sedative, myorelaxant actions in mice or amnestic effects in rats; however, 6-chloro-3'-nitroflavone antagonized diazepam-induced antianxiety action, anticonvulsion, short-term, and long-term amnesia and motor incoordination. These biochemical, electrophysiological, and pharmacological results suggest that 6-chloro-3'-nitroflavone behaves as an antagonist of the BDZ-BSs.
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Affiliation(s)
- H Viola
- Instituto de Biología Celular y Neurosciencias, Facultad de Medicina, Buenos Aires, Argentina
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Viola H, Marder M, Nuñez J, Izquierdo L, Wasowski C, Wolfman C, Ardenghi P, Barros D, Medina JH, Paladini AC. 6-Methyl-3'-bromoflavone, a high-affinity ligand for the benzodiazepine binding site of the GABA(A) receptor with some antagonistic properties. Biochem Biophys Res Commun 1999; 262:643-6. [PMID: 10471378 DOI: 10.1006/bbrc.1999.1273] [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] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
6-Methyl-3'-bromoflavone inhibited [(3)H]flunitrazepam binding to the benzodiazepine binding site of the GABA(A) receptor (BDZ-bs) with Ki values between 10 and 50 nM in different brain regions. The GABA ratio of 1.03 for [(3)H]flunitrazepam binding to cerebral cortex, 0.76 for cerebellum, 0.7 for hippocampus, 0.7 for striatum, and 0.8 for spinal cord indicated an antagonistic or weak inverse agonistic profile of 6-methyl-3'-bromoflavone on BDZ-bs. Unlike classical benzodiazepines, it had no anticonvulsant, anxiolytic, myorelaxant, sedative, amnestic or motor incoordination effects. However, it antagonized the muscle relaxant, the sedative effect, and the changes in locomotor activity induced by diazepam. Taken together, these findings suggest that 6-methyl-3'-bromoflavone has an antagonistic profile on the BDZ-bs.
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Affiliation(s)
- H Viola
- Facultad de Medicina, Instituto de Biología Celular, Paraguay 2155 (1121), Buenos Aires, Argentina
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Paladini AC, Marder M, Viola H, Wolfman C, Wasowski C, Medina JH. Flavonoids and the central nervous system: from forgotten factors to potent anxiolytic compounds. J Pharm Pharmacol 1999; 51:519-26. [PMID: 10411210 DOI: 10.1211/0022357991772790] [Citation(s) in RCA: 100] [Impact Index Per Article: 4.0] [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: 10/31/2022]
Abstract
The list of activities of plant flavonoids did not include effects on the central nervous system (CNS) up to 1990, when our laboratory described the existence of natural anxiolytic flavonoids. The first of these was chrysin (5,7-dihydroxyflavone), followed by apigenin (5,7,4'-trihydroxyflavone) and flavone itself. Semisynthetic derivatives of flavone obtained by introducing halogens, nitro groups or both in its molecule, give rise to high affinity ligands for the benzodiazepine receptor, active in-vivo; 6,3'-dinitroflavone, for example, is an anxiolytic drug 30 times more potent than diazepam. The data collected in this paper make clear that some natural flavonoids are CNS-active molecules and that the chemical modification of the flavone nucleus dramatically increases their anxiolytic potency.
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Affiliation(s)
- A C Paladini
- Instituto de Quimica y Fisicoquimica Biologicas, Facultad de Farmacia y Bioquimica, Buenos Aires, Argentina
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Wolfman C, Viola H, Marder M, Ardenghi P, Wasowski C, Schröder N, Izquierdo I, Rúveda E, Paladini A, Medina JH. Pharmacological characterization of 6-bromo-3'-nitroflavone, a synthetic flavonoid with high affinity for the benzodiazepine receptors. Pharmacol Biochem Behav 1998; 61:239-46. [PMID: 9768558 DOI: 10.1016/s0091-3057(98)00088-4] [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] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/09/2023]
Abstract
6-Bromo-3'-nitroflavone is a synthetic flavone derivative that selectively recognizes benzodiazepine receptors and has potent anxiolytic-like effects. Here, we describe in detail its pharmacological characterization. When i.p. injected in mice, 6-bromo-3'-nitroflavone (0.01-0.3 mg/kg) had an anxiolytic-like effect in the elevated plus-maze test. This effect was blocked by the specific benzodiazepine receptor antagonist, flumazenil. In addition, it exhibited anxiolytic-like actions when given orally (1 mg/kg). 6-Bromo-3'-nitroflavone did not exhibit myorelaxant effects (up to 30 mg/kg, i.p.). Unlike diazepam, this flavonoid produced no anterograde amnesia in a one-trial inhibitory avoidance learning. On the other hand, 6-bromo-3'-nitroflavone possessed mild anticonvulsant activity (0.1 mg/kg, i.p.) and provoked sedative-depressant actions only at doses 100-1000 times higher than those producing anxiolytic-like effects. 6-Bromo-3'-nitroflavone (0.1-1 mM) produced a lower potentiation of gamma-amino-butyric acid (GABA)-stimulated 36Cl- influx (126-138%) in comparison to diazepam (0.1 mM: 166%) in cerebral cortical membrane vesicles. Taken together, these findings suggest that 6-bromo-3'-nitroflavone has anxiolytic-like action possibly behaving as a partial agonist of the benzodiazepine receptors.
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Affiliation(s)
- C Wolfman
- Instituto de Biología Celular y Neurociencias, Facultad de Medicina, Buenos Aires, Argentina
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Marder M, Viola H, Bacigaluppo JA, Colombo MI, Wasowski C, Wolfman C, Medina JH, Rúveda EA, Paladini AC. Detection of benzodiazepine receptor ligands in small libraries of flavone derivatives synthesized by solution phase combinatorial chemistry. Biochem Biophys Res Commun 1998; 249:481-5. [PMID: 9712722 DOI: 10.1006/bbrc.1998.9146] [Citation(s) in RCA: 58] [Impact Index Per Article: 2.2] [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: 11/22/2022]
Abstract
Solution phase combinatorial synthesis of flavone derivatives and evaluation of their affinity for the central benzodiazepine receptors is described. The libraries preparation is simple and provides a convenient method for rapid compound generation and screening. Thirty one new compounds were obtained of which the most promising, as high affinity benzodiazepine receptor ligands, were 6-bromo-3'-fluoroflavone; 6,3'-dichloroflavone; 6-bromo-3'-chloroflavone and 6-chloro-3'-bromoflavone.
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Affiliation(s)
- M Marder
- Facultad de Farmacia y Bioquímica, Instituto de Química y Fisicoquímica Biológicas, Junín 956, Buenos Aires, 1113, Argentina
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Abstract
Benzodiazepines (BDZs) are the most widely prescribed class of psychoactive drugs in current therapeutic use, despite the important unwanted side-effects that they produce such as sedation, myorelaxation, ataxia, amnesia, ethanol and barbiturate potentiation and tolerance. Searching for safer BDZ-receptor (BDZ-R) ligands we have recently demonstrated the existence of a new family of ligands which have a flavonoid structure. First isolated from plants used as tranquilizers in folkloric medicine, some natural flavonoids have shown to possess a selective and relatively mild affinity for BDZ-Rs and a pharmacological profile compatible with a partial agonistic action. In a logical extension of this discovery various synthetic derivatives of those compounds, such as 6,3'-dinitroflavone were found to have a very potent anxiolytic effect not associated with myorelaxant, amnestic or sedative actions. This dinitro compound, in particular, exhibits a high affinity for the BDZ-Rs (Ki = 12-30 nM). Due to their selective pharmacological profile and low intrinsic efficacy at the BDZ-Rs, flavonoid derivatives, such as those described, could represent an improved therapeutic tool in the treatment of anxiety. In addition, several flavone derivatives may provide important leads for the development of potent and selective BDZ-Rs ligands.
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Affiliation(s)
- J H Medina
- Instituto de Biologia Celular y Neurociencias, Facultad de Medicina, UBA, Paraguay, Buenos Aires, Argentina
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Wolfman C, Viola H, Marder M, Wasowski C, Ardenghi P, Izquierdo I, Paladini AC, Medina JH. Anxioselective properties of 6,3'-dinitroflavone, a high-affinity benzodiazepine receptor ligand. Eur J Pharmacol 1996; 318:23-30. [PMID: 9007508 DOI: 10.1016/s0014-2999(96)00784-4] [Citation(s) in RCA: 61] [Impact Index Per Article: 2.2] [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: 02/03/2023]
Abstract
6,3'-Dintroflavone is a synthetic flavone derivative with high affinity for central benzodiazepine receptors that has anxiolytic effects. Here, we describe its biochemical and pharmacological characterization. 6,3'-Dinitroflavone inhibited differentially [3H]flunitrazepam binding to central benzodiazepine receptors in several brain regions, showing a lower Ki value in the cerebellum (central benzodiazepine receptor type I-enriched area), and a higher Ki value in the spinal cord and in the dentate gyrus (central benzodiazepine receptor type II-enriched area). When i.p. injected in mice, 6,3'-dinitroflavone had a potent anxiolytic effect in the elevated plus maze test. This effect was blocked by the specific central benzodiazepine receptor antagonist, Ro 15-1788. 6,3'-Dinitroflavone did not exhibit anticonvulsant or myorelaxant effects in mice or amnestic effects in rats. Moreover, it abolished the myorelaxant effect of diazepam. On the other hand, 6,3'-dinitroflavone possessed a mild sedative action only at doses 100-300-fold greater than the anxiolytic one. Based on these findings, we suggest that 6,3'-dinitroflavone has a benzodiazepine partial agonist profile, with low selectivity for central benzodiazepine receptor types I and II.
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Affiliation(s)
- C Wolfman
- Instituo de Biología Celular, Facultad de Medicina, Universidad de Buenos Aires, Paraguay, Argentina
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Marder M, Viola H, Wasowski C, Wolfman C, Waterman PG, Cassels BK, Medina JG, Paladini AC. 6-Bromoflavone, a high affinity ligand for the central benzodiazepine receptors is a member of a family of active flavonoids. Biochem Biophys Res Commun 1996; 223:384-9. [PMID: 8670291 DOI: 10.1006/bbrc.1996.0903] [Citation(s) in RCA: 52] [Impact Index Per Article: 1.9] [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: 02/01/2023]
Abstract
6-Bromoflavone, obtained by bromination of flavanone, binds to central benzodiazepine receptors with a Ki=70 nM and has a clear anxiolytic activity in mice, at 0.5 mg/kg i.p. A survey of the structure/affinity relationship for those receptors in a series of natural and synthetic flavonoids is presented.
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Affiliation(s)
- M Marder
- Instituto de Química y Fisicoquímica Biológicas, Facultad de Farmaciay Bioquímica, Buenos Aires, Argentina
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Marder M. Order versus symmetry in pinwheel tilings of the plane. Phys Rev B Condens Matter 1993; 48:13971-13973. [PMID: 10007798 DOI: 10.1103/physrevb.48.13971] [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: 04/12/2023]
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Marder M. Comment on "Universal scaling of the stress field at the vicinity of a wedge crack in two dimensions and oscillatory self-similar corrections to scaling". Phys Rev Lett 1992; 68:2253. [PMID: 10045347 DOI: 10.1103/physrevlett.68.2253] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
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Marder M. Marder replies. Phys Rev Lett 1991; 67:3043. [PMID: 10044624 DOI: 10.1103/physrevlett.67.3043] [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: 05/23/2023]
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Marder M. Crystals with a twist. Phys Rev A Gen Phys 1989; 40:4824-4827. [PMID: 9902739 DOI: 10.1103/physreva.40.4824] [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: 05/22/2023]
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Abstract
The segment of our society over age 65 is growing, and many more of these people are keeping their teeth for a longer period of time. This suggests that there will be additional need for periodontal therapy in the future, but it also implies that disease-related events must be distinguished from age-related changes. Changes in the periodontium with aging are reviewed, and periodontal disease management strategies in the older patient are discussed.
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