Chang-You Lin - Academia.edu (original) (raw)
Papers by Chang-You Lin
Scientific Reports
Cell development and behavior are driven by internal genetic programming, but the external microe... more Cell development and behavior are driven by internal genetic programming, but the external microenvironment is increasingly recognized as a significant factor in cell differentiation, migration, and in the case of cancer, metastatic progression. Yet it remains unclear how the microenvironment influences cell processes, especially when examining cell motility. One factor that affects cell motility is cell mechanics, which is known to be related to substrate stiffness. Examining how cells interact with each other in response to mechanically differential substrates would allow an increased understanding of their coordinated cell motility. In order to probe the effect of substrate stiffness on tumor related cells in greater detail, we created hard–soft–hard (HSH) polydimethylsiloxane (PDMS) substrates with alternating regions of different stiffness (200 and 800 kPa). We then cultured WI-38 fibroblasts and A549 epithelial cells to probe their motile response to the substrates. We found t...
Physical Review A
The localized low-energy interfacial excitations, or Nambu-Goldstone modes, of phase-segregated b... more The localized low-energy interfacial excitations, or Nambu-Goldstone modes, of phase-segregated binary mixtures of Bose-Einstein condensates are investigated analytically by means of a doubleparabola approximation (DPA) to the Lagrangian density in Gross-Pitaevskii theory for a system in a uniform potential. Within this model analytic expressions are obtained for the excitations underlying capillary waves or "ripplons" for arbitrary strength K (> 1) of the phase segregation. The dispersion relation ω ∝ k 3/2 is derived directly from the Bogoliubov-de Gennes equations in limit that the wavelength 2π/k is much larger than the healing length ξ. The proportionality constant in the dispersion relation provides the static interfacial tension. A correction term in ω(k) of order k 5/2 is calculated analytically, entailing a finite-wavelength correction factor (1 + √ K−1 kξ 4 √ 2 (√ 2+ √ K−1)). This prediction may be tested experimentally using (quasi-)uniform optical-box traps. Explicit expressions are obtained for the structural deformation of the interface due to the passing of the capillary wave. It is found that the amplitude of the wave is enhanced by an amount that is quadratic in the ratio of the phase velocity ω/k to the sound velocity c. For generic asymmetric mixtures consisting of condensates with unequal healing lengths an additional modulation is predicted of the common value of the condensate densities at the interface.
Physica A: Statistical Mechanics and its Applications, 2015
Accurate and useful analytic approximations are developed for order parameter profiles and interf... more Accurate and useful analytic approximations are developed for order parameter profiles and interfacial tensions of phase-separated binary mixtures of Bose-Einstein condensates. The pure condensates 1 and 2, each of which contains a particular species of atoms, feature healing lengths ξ 1 and ξ 2. The inter-atomic interactions are repulsive. In particular, the effective inter-species repulsive interaction strength is K. A triple-parabola approximation (TPA) is proposed, to represent closely the energy density featured in Gross-Pitaevskii (GP) theory. This TPA allows us to define a model, which is a handy alternative to the full GP theory, while still possessing a simple analytic solution. The TPA offers a significant improvement over the recently introduced double-parabola approximation (DPA). In particular, a more accurate amplitude for the wall energy (of a single condensate) is derived and, importantly, a more correct expression for the interfacial tension (of two condensates) is obtained, which describes better its dependence on K in the strong segregation regime, while also the interface profiles undergo a qualitative improvement.
While inhaled aerosol drugs can deliver substantial doses of medication directly to the lungs, al... more While inhaled aerosol drugs can deliver substantial doses of medication directly to the lungs, altered patterns of ventilation associated with obstructive lung diseases cause inhaled drugs to deposit non-uniformly. Some lung regions receive very high local doses of medication while other regions go untreated. This presentation concerns recent research suggesting that the addition of surfactant to the aerosol will disperse these drugs more effectively after deposition on the airway surface liquid (ASL). The enhanced dispersion results from the creation of surface tension gradients on the ASL. Surfactants in the deposited droplets adsorb and decrease surface tension locally. Marangoni stresses drive the droplet to spread outward over higher surface tension regions of the surrounding ASL. In this way, drug that initially deposits on mucus obstructions spread over the surface of the obstruction to reach poorly accessible targets. A considerable body of prior research exists concerning t...
A triple junction in a three-phase fluid system is modeled by a mean-field density functional the... more A triple junction in a three-phase fluid system is modeled by a mean-field density functional theory. We use a variational approach to find the Euler-Lagrange equations. Analytic solutions are obtained in the two-phase regions at large distances from the triple junction. We employ a triangular grid and use a successive over-relaxation method to find numerical solutions in the entire domain for the special case of equal interfacial tensions for the two-phase interfaces. We use the Kerins-Boiteux formula to obtain a line tension associated with the triple junction. This line tension turns out to be negative. We associate line adsorption with the change of line tension as the governing potentials change.
Physical Review A, 2015
Interfacial profiles and interfacial tensions of phase-separated binary mixtures of Bose-Einstein... more Interfacial profiles and interfacial tensions of phase-separated binary mixtures of Bose-Einstein condensates are studied theoretically. The two condensates are characterized by their respective healing lengths ξ 1 and ξ 2 and by the inter-species repulsive interaction K. An exact solution to the Gross-Pitaevskii (GP) equations is obtained for the special case ξ 2 /ξ 1 = 1/2 and K = 3/2. Furthermore, applying a double-parabola approximation (DPA) to the energy density featured in GP theory allows us to define a DPA model, which is much simpler to handle than GP theory but nevertheless still captures the main physics. In particular, a compact analytic expression for the interfacial tension is derived that is useful for all ξ 1 , ξ 2 and K. An application to wetting phenomena is presented for condensates adsorbed at an optical wall. The wetting phase boundary obtained within the DPA model nearly coincides with the exact one in GP theory.
Physical Review E, 2012
A three-phase contact line in a three-phase fluid system is modeled by a mean-field density funct... more A three-phase contact line in a three-phase fluid system is modeled by a mean-field density functional theory. We use a variational approach to find the Euler-Lagrange equations. Analytic solutions are obtained in the two-phase regions at large distances from the contact line. We employ a triangular grid and use a successive over-relaxation method to find numerical solutions in the entire domain for the special case of equal interfacial tensions for the two-phase interfaces. We use the Kerins-Boiteux formula to obtain a line tension associated with the contact line. This line tension turns out to be negative. We associate line adsorption with the change of line tension as the governing potentials change.
We investigate generalized potentials for a mean-field density functional theory of a three-phase... more We investigate generalized potentials for a mean-field density functional theory of a three-phase contact line. Compared to the symmetrical potential introduced in our previous article [1], the three minima of these potentials form a small triangle located arbitrarily within the Gibbs triangle, which is more realistic for ternary fluid systems. We multiply linear functions that vanish at edges and vertices of the small triangle, yielding potentials in the form of quartic polynomials. We find that a subset of such potentials has simple analytic far-field solutions, and is a linear transformation of our original potential. By scaling, we can relate their solutions to those of our original potential. For special cases, the lengths of the sides of the small triangle are proportional to the corresponding interfacial tensions. For the case of equal interfacial tensions, we calculate a line tension that is proportional to the area of the small triangle.
Scientific Reports
Cell development and behavior are driven by internal genetic programming, but the external microe... more Cell development and behavior are driven by internal genetic programming, but the external microenvironment is increasingly recognized as a significant factor in cell differentiation, migration, and in the case of cancer, metastatic progression. Yet it remains unclear how the microenvironment influences cell processes, especially when examining cell motility. One factor that affects cell motility is cell mechanics, which is known to be related to substrate stiffness. Examining how cells interact with each other in response to mechanically differential substrates would allow an increased understanding of their coordinated cell motility. In order to probe the effect of substrate stiffness on tumor related cells in greater detail, we created hard–soft–hard (HSH) polydimethylsiloxane (PDMS) substrates with alternating regions of different stiffness (200 and 800 kPa). We then cultured WI-38 fibroblasts and A549 epithelial cells to probe their motile response to the substrates. We found t...
Physical Review A
The localized low-energy interfacial excitations, or Nambu-Goldstone modes, of phase-segregated b... more The localized low-energy interfacial excitations, or Nambu-Goldstone modes, of phase-segregated binary mixtures of Bose-Einstein condensates are investigated analytically by means of a doubleparabola approximation (DPA) to the Lagrangian density in Gross-Pitaevskii theory for a system in a uniform potential. Within this model analytic expressions are obtained for the excitations underlying capillary waves or "ripplons" for arbitrary strength K (> 1) of the phase segregation. The dispersion relation ω ∝ k 3/2 is derived directly from the Bogoliubov-de Gennes equations in limit that the wavelength 2π/k is much larger than the healing length ξ. The proportionality constant in the dispersion relation provides the static interfacial tension. A correction term in ω(k) of order k 5/2 is calculated analytically, entailing a finite-wavelength correction factor (1 + √ K−1 kξ 4 √ 2 (√ 2+ √ K−1)). This prediction may be tested experimentally using (quasi-)uniform optical-box traps. Explicit expressions are obtained for the structural deformation of the interface due to the passing of the capillary wave. It is found that the amplitude of the wave is enhanced by an amount that is quadratic in the ratio of the phase velocity ω/k to the sound velocity c. For generic asymmetric mixtures consisting of condensates with unequal healing lengths an additional modulation is predicted of the common value of the condensate densities at the interface.
Physica A: Statistical Mechanics and its Applications, 2015
Accurate and useful analytic approximations are developed for order parameter profiles and interf... more Accurate and useful analytic approximations are developed for order parameter profiles and interfacial tensions of phase-separated binary mixtures of Bose-Einstein condensates. The pure condensates 1 and 2, each of which contains a particular species of atoms, feature healing lengths ξ 1 and ξ 2. The inter-atomic interactions are repulsive. In particular, the effective inter-species repulsive interaction strength is K. A triple-parabola approximation (TPA) is proposed, to represent closely the energy density featured in Gross-Pitaevskii (GP) theory. This TPA allows us to define a model, which is a handy alternative to the full GP theory, while still possessing a simple analytic solution. The TPA offers a significant improvement over the recently introduced double-parabola approximation (DPA). In particular, a more accurate amplitude for the wall energy (of a single condensate) is derived and, importantly, a more correct expression for the interfacial tension (of two condensates) is obtained, which describes better its dependence on K in the strong segregation regime, while also the interface profiles undergo a qualitative improvement.
While inhaled aerosol drugs can deliver substantial doses of medication directly to the lungs, al... more While inhaled aerosol drugs can deliver substantial doses of medication directly to the lungs, altered patterns of ventilation associated with obstructive lung diseases cause inhaled drugs to deposit non-uniformly. Some lung regions receive very high local doses of medication while other regions go untreated. This presentation concerns recent research suggesting that the addition of surfactant to the aerosol will disperse these drugs more effectively after deposition on the airway surface liquid (ASL). The enhanced dispersion results from the creation of surface tension gradients on the ASL. Surfactants in the deposited droplets adsorb and decrease surface tension locally. Marangoni stresses drive the droplet to spread outward over higher surface tension regions of the surrounding ASL. In this way, drug that initially deposits on mucus obstructions spread over the surface of the obstruction to reach poorly accessible targets. A considerable body of prior research exists concerning t...
A triple junction in a three-phase fluid system is modeled by a mean-field density functional the... more A triple junction in a three-phase fluid system is modeled by a mean-field density functional theory. We use a variational approach to find the Euler-Lagrange equations. Analytic solutions are obtained in the two-phase regions at large distances from the triple junction. We employ a triangular grid and use a successive over-relaxation method to find numerical solutions in the entire domain for the special case of equal interfacial tensions for the two-phase interfaces. We use the Kerins-Boiteux formula to obtain a line tension associated with the triple junction. This line tension turns out to be negative. We associate line adsorption with the change of line tension as the governing potentials change.
Physical Review A, 2015
Interfacial profiles and interfacial tensions of phase-separated binary mixtures of Bose-Einstein... more Interfacial profiles and interfacial tensions of phase-separated binary mixtures of Bose-Einstein condensates are studied theoretically. The two condensates are characterized by their respective healing lengths ξ 1 and ξ 2 and by the inter-species repulsive interaction K. An exact solution to the Gross-Pitaevskii (GP) equations is obtained for the special case ξ 2 /ξ 1 = 1/2 and K = 3/2. Furthermore, applying a double-parabola approximation (DPA) to the energy density featured in GP theory allows us to define a DPA model, which is much simpler to handle than GP theory but nevertheless still captures the main physics. In particular, a compact analytic expression for the interfacial tension is derived that is useful for all ξ 1 , ξ 2 and K. An application to wetting phenomena is presented for condensates adsorbed at an optical wall. The wetting phase boundary obtained within the DPA model nearly coincides with the exact one in GP theory.
Physical Review E, 2012
A three-phase contact line in a three-phase fluid system is modeled by a mean-field density funct... more A three-phase contact line in a three-phase fluid system is modeled by a mean-field density functional theory. We use a variational approach to find the Euler-Lagrange equations. Analytic solutions are obtained in the two-phase regions at large distances from the contact line. We employ a triangular grid and use a successive over-relaxation method to find numerical solutions in the entire domain for the special case of equal interfacial tensions for the two-phase interfaces. We use the Kerins-Boiteux formula to obtain a line tension associated with the contact line. This line tension turns out to be negative. We associate line adsorption with the change of line tension as the governing potentials change.
We investigate generalized potentials for a mean-field density functional theory of a three-phase... more We investigate generalized potentials for a mean-field density functional theory of a three-phase contact line. Compared to the symmetrical potential introduced in our previous article [1], the three minima of these potentials form a small triangle located arbitrarily within the Gibbs triangle, which is more realistic for ternary fluid systems. We multiply linear functions that vanish at edges and vertices of the small triangle, yielding potentials in the form of quartic polynomials. We find that a subset of such potentials has simple analytic far-field solutions, and is a linear transformation of our original potential. By scaling, we can relate their solutions to those of our original potential. For special cases, the lengths of the sides of the small triangle are proportional to the corresponding interfacial tensions. For the case of equal interfacial tensions, we calculate a line tension that is proportional to the area of the small triangle.