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Abstract
We study the regimes of a diluted dipolar system through Monte Carlo numerical simulations in the NVT ensemble. To accelerate the dynamics, several approximations and speed-up algorithms are proposed and tested. In particular, it turns out that "cluster move Monte Carlo" algorithm speeds-up to two decades faster than the traditional Monte Carlo, depending on temperature and density. We find simple-fluid, chain-fluid, ring-fluid, gel, and antiparallel columnar regimes, which are studied and characterized through positional, orientational, and thermodynamical observables.
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Affiliation(s)
- D A Martin
- Instituto de Investigaciones Físicas de Mar del Plata (IFIMAR), CONICET and Universidad Nacional de Mar del Plata, Funes no. 3350, 7600, Mar del Plata, Argentina
| | - T S Grigera
- Instituto de Física de Líquidos y Sistemas Biológicos (IFLYSIB), CONICET and Facultad de Ciencias Exactas, Universidad Nacional de La Plata, Calle 59 no. 789, B1900BTE La Plata, Argentina.,CCT CONICET La Plata, Consejo Nacional de Investigaciones Científicas y Técnicas, Argentina
| | - V I Marconi
- FaMAF and IFEG (UNC-CONICET), Universidad Nacional de Córdoba, X5000HUA Córdoba, Argentina
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2
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Guidobaldi HA, Jeyaram Y, Condat CA, Oviedo M, Berdakin I, Moshchalkov VV, Giojalas LC, Silhanek AV, Marconi VI. Disrupting the wall accumulation of human sperm cells by artificial corrugation. Biomicrofluidics 2015; 9:024122. [PMID: 26015834 PMCID: PMC4409620 DOI: 10.1063/1.4918979] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/06/2015] [Accepted: 04/14/2015] [Indexed: 05/14/2023]
Abstract
Many self-propelled microorganisms are attracted to surfaces. This makes their dynamics in restricted geometries very different from that observed in the bulk. Swimming along walls is beneficial for directing and sorting cells, but may be detrimental if homogeneous populations are desired, such as in counting microchambers. In this work, we characterize the motion of human sperm cells ∼60 μm long, strongly confined to ∼25 μm shallow chambers. We investigate the nature of the cell trajectories between the confining surfaces and their accumulation near the borders. Observed cell trajectories are composed of a succession of quasi-circular and quasi-linear segments. This suggests that the cells follow a path of intermittent trappings near the top and bottom surfaces separated by stretches of quasi-free motion in between the two surfaces, as confirmed by depth resolved confocal microscopy studies. We show that the introduction of artificial petal-shaped corrugation in the lateral boundaries removes the tendency of cells to accumulate near the borders, an effect which we hypothesize may be valuable for microfluidic applications in biomedicine.
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Affiliation(s)
- H A Guidobaldi
- IIByT-CONICET and FCEFyN, Universidad Nacional de Córdoba , X5016GCA Córdoba, Argentina
| | - Y Jeyaram
- Institute for Nanoscale Physics and Chemistry , KU Leuven, B-3001 Leuven, Belgium
| | - C A Condat
- FaMAF, Universidad Nacional de Córdoba and IFEG-CONICET , X5000HUA Córdoba, Argentina
| | - M Oviedo
- IIByT-CONICET and FCEFyN, Universidad Nacional de Córdoba , X5016GCA Córdoba, Argentina
| | - I Berdakin
- FaMAF, Universidad Nacional de Córdoba and IFEG-CONICET , X5000HUA Córdoba, Argentina
| | - V V Moshchalkov
- Institute for Nanoscale Physics and Chemistry , KU Leuven, B-3001 Leuven, Belgium
| | - L C Giojalas
- IIByT-CONICET and FCEFyN, Universidad Nacional de Córdoba , X5016GCA Córdoba, Argentina
| | - A V Silhanek
- Départment de Physique, Université de Liège , B-4000 Sart Tilman, Belgium
| | - V I Marconi
- FaMAF, Universidad Nacional de Córdoba and IFEG-CONICET , X5000HUA Córdoba, Argentina
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3
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Guidobaldi A, Jeyaram Y, Berdakin I, Moshchalkov VV, Condat CA, Marconi VI, Giojalas L, Silhanek AV. Geometrical guidance and trapping transition of human sperm cells. Phys Rev E Stat Nonlin Soft Matter Phys 2014; 89:032720. [PMID: 24730887 DOI: 10.1103/physreve.89.032720] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/19/2013] [Indexed: 05/14/2023]
Abstract
The guidance of human sperm cells under confinement in quasi-2D microchambers is investigated using a purely physical method to control their distribution. Transport property measurements and simulations are performed with diluted sperm populations, for which effects of geometrical guidance and concentration are studied in detail. In particular, a trapping transition at convex angular wall features is identified and analyzed. We also show that highly efficient microratchets can be fabricated by using curved asymmetric obstacles to take advantage of the spermatozoa specific swimming strategy.
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Affiliation(s)
- A Guidobaldi
- Instituto de Investigaciones Biológicas y Tecnológicas, CONICET and Centro de Biología Celular y Molecular, Universidad Nacional de Córdoba, Ciudad Universitaria, 5000-Córdoba, Argentina
| | - Y Jeyaram
- Institute for Nanoscale Physics and Chemistry, KU Leuven, B-3001 Leuven, Belgium
| | - I Berdakin
- Facultad de Matemática, Astronomía y Física, Universidad Nacional de Córdoba and IFEG-CONICET, X5000HUA Córdoba, Argentina
| | - V V Moshchalkov
- Institute for Nanoscale Physics and Chemistry, KU Leuven, B-3001 Leuven, Belgium
| | - C A Condat
- Facultad de Matemática, Astronomía y Física, Universidad Nacional de Córdoba and IFEG-CONICET, X5000HUA Córdoba, Argentina
| | - V I Marconi
- Facultad de Matemática, Astronomía y Física, Universidad Nacional de Córdoba and IFEG-CONICET, X5000HUA Córdoba, Argentina
| | - L Giojalas
- Instituto de Investigaciones Biológicas y Tecnológicas, CONICET and Centro de Biología Celular y Molecular, Universidad Nacional de Córdoba, Ciudad Universitaria, 5000-Córdoba, Argentina
| | - A V Silhanek
- Département de Physique, Université de Liège, B-4000 Sart Tilman, Belgium
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4
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Berdakin I, Jeyaram Y, Moshchalkov VV, Venken L, Dierckx S, Vanderleyden SJ, Silhanek AV, Condat CA, Marconi VI. Influence of swimming strategy on microorganism separation by asymmetric obstacles. Phys Rev E Stat Nonlin Soft Matter Phys 2013; 87:052702. [PMID: 23767561 DOI: 10.1103/physreve.87.052702] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/08/2013] [Indexed: 05/27/2023]
Abstract
It has been shown that a nanoliter chamber separated by a wall of asymmetric obstacles can lead to an inhomogeneous distribution of self-propelled microorganisms. Although it is well established that this rectification effect arises from the interaction between the swimmers and the noncentrosymmetric pillars, here we demonstrate numerically that its efficiency is strongly dependent on the detailed dynamics of the individual microorganism. In particular, for the case of run-and-tumble dynamics, the distribution of run lengths, the rotational diffusion, and the partial preservation of run orientation memory through a tumble are important factors when computing the rectification efficiency. In addition, we optimize the geometrical dimensions of the asymmetric pillars in order to maximize the swimmer concentration and we illustrate how it can be used for sorting by swimming strategy in a long array of parallel obstacles.
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Affiliation(s)
- I Berdakin
- Facultad de Matemática, Astronomía y Física, Universidad Nacional de Córdoba and IFEG-CONICET, X5000HUA Córdoba, Argentina
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5
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Pérez-Junquera A, Marconi VI, Kolton AB, Alvarez-Prado LM, Souche Y, Alija A, Vélez M, Anguita JV, Alameda JM, Martín JI, Parrondo JMR. Crossed-ratchet effects for magnetic domain wall motion. Phys Rev Lett 2008; 100:037203. [PMID: 18233032 DOI: 10.1103/physrevlett.100.037203] [Citation(s) in RCA: 3] [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: 08/31/2007] [Indexed: 05/25/2023]
Abstract
We study both experimentally and theoretically the driven motion of domain walls in extended amorphous magnetic films patterned with a periodic array of asymmetric holes. We find two crossed-ratchet effects of opposite sign that change the preferred sense for domain wall propagation, depending on whether a flat or a kinked wall is moving. By solving numerically a simple phi(4) model we show that the essential physical ingredients for this effect are quite generic and could be realized in other experimental systems involving elastic interfaces moving in multidimensional ratchet potentials.
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Affiliation(s)
- A Pérez-Junquera
- Departamento de Física, Universidad de Oviedo-CINN, Oviedo, Spain
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Marconi VI, Jagla EA. Diffuse interface approach to brittle fracture. Phys Rev E Stat Nonlin Soft Matter Phys 2005; 71:036110. [PMID: 15903496 DOI: 10.1103/physreve.71.036110] [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: 01/22/2004] [Revised: 12/13/2004] [Indexed: 05/02/2023]
Abstract
We present a continuum model for the propagation of cracks and fractures in brittle materials. The components of the strain tensor epsilon are the fundamental variables. The evolution equations are based on a free energy that reduces to that of linear elasticity for small epsilon, and accounts for cracks through energy saturation at large values of epsilon. We regularize the model by including terms dependent on gradients of epsilon in the free energy. No additional fields are introduced, and then the whole dynamics is perfectly defined. We show that the model is able to reproduce basic facts in fracture physics, like the Griffith's dependence of the critical stress as a minus one-half power of the crack length. In addition, regularization makes the results insensitive to the numerical mesh used, something not at all trivial in crack modeling. We present an example of the application of the model to predict the growth and curving of cracks in a nontrivial geometrical configuration.
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Affiliation(s)
- V I Marconi
- The Abdus Salam ICTP, Strada Costiera 11, 34014 Trieste, Italy
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Abstract
We study the effect of thermal fluctuations in a fully frustrated Josephson junction array driven by a current I larger than the apparent critical current I(c)(T). We calculate numerically the behavior of the chiral order parameter of Z2 symmetry and the transverse helicity modulus [related to the U(1) symmetry] as a function of temperature. We find that the Z2 transition occurs at a temperature T(Z2)(I) which is lower than the temperature T(U(1))(I) for the U(1) transition. Both transitions could be observed experimentally from measurements of the longitudinal and transverse voltages.
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Affiliation(s)
- V I Marconi
- Centro Atómico Bariloche, 8400 S. C. de Bariloche, Rio Negro, Argentina
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