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Biomimetic Design and Fabrication of Interior Architecture of Tissue Scaffolds Using Solid Freeform Fabrication
Modeling, design and fabrication of tissue scaffolds with intricate architecture,
porosity and pore size for desired tissue properties presents a challenge in tissue engineering.
This paper will present the details of our development in designing and fabrication of the
interior architecture of scaffolds using a novel design approach. The Interior Architecture
Design (IAD) approach seeks to generate scaffold layered freeform fabrication tool path without
forming complicated 3D CAD scaffold models. This involves: applying the principle of layered
manufacturing to determine the scaffold individual layered process planes and layered contour;
defining the 2D characteristic patterns of the scaffold building blocks (unit cells) to form the
Interior Scaffold Pattern; and the generation of process tool path for freeform fabrication of
these scaffolds with the specified interior architecture. Feasibility studies applying the IAD
algorithm to example models and the generation of fabrication planning instructions will be
presented.Mechanical Engineerin
Binding of Oppositely Charged Membranes and Membrane Reorganization
We consider the electrostatic interaction between two rigid membranes, with
different surface charge densities of opposite sign, across an aqueous solution
without added salt. Exact solutions to the nonlinear Poisson-Boltzmann equation
are obtained and their physical meaning discussed. We also calculate the
electrostatic contribution to the free energy and discuss the renormalization
of the area per head group of the charged lipids arising from the Coulomb
interaction.Comment: 13 pages, 6 figures, to be published in EJP
Phase Transitions in Lyotropic Nematic Gels
In this paper, we discuss the equilibrium phases and collapse transitions of
a lyotropic nematic gel immersed in an isotropic solvent. A nematic gel
consists of a cross-linked polymer network with rod-like molecules embedded in
it. Upon decreasing the quality of the solvent, we find that a lyotropic
nematic gel undergoes a discontinuous volume change accompanied by an
isotropic-nematic transition. We also present phase diagrams that these systems
may exhibit. In particular, we show that coexistence of two isotropic phases,
of two nematic phases, or of an isotropic and a nematic phase can occur.Comment: 13 pages Revtex, 10 figures, submitted to EPJ
Non-equilibrium fluctuations and mechanochemical couplings of a molecular motor
We investigate theoretically the violations of Einstein and Onsager
relations, and the efficiency for a single processive motor operating far from
equilibrium using an extension of the two-state model introduced by Kafri {\em
et al.} [Biophys. J. {\bf 86}, 3373 (2004)]. With the aid of the Fluctuation
Theorem, we analyze the general features of these violations and this
efficiency and link them to mechanochemical couplings of motors. In particular,
an analysis of the experimental data of kinesin using our framework leads to
interesting predictions that may serve as a guide for future experiments.Comment: 4 pages, 4 figures, accepted to Phys. Rev. Let
Heteroepitaxy of deposited amorphous layer by pulsed electron-beam irradiation
We demonstrate that a single short pulse of electron irradiation of appropriate energy is capable of recrystallizing epitaxially an amorphous Ge layer deposited on either or Si single-crystal substrate. The primary defects observed in the case were dislocations, whereas stacking faults were observed in samples
Structural evaluation of concrete expanded polystyrene sandwich panels for slab applications
Sandwich panels are being extensively and increasingly used in building construction because they are light in weight, energy efficient, aesthetically attractive and can be easily handled and erected. This paper presents a structural evaluation of Concrete-Expanded Polystyrene (CEPS) sandwich panels for slab applications using finite element modeling approach. CEPS panels are made of expanded polystyrene foam sandwiched between concrete skins. The use of foam in the middle of sandwich panel reduces the weight of the structure and also acts as insulation against thermal, acoustics and vibration. Applying reinforced concrete skin to both sides of panel takes the advantages of the sandwich concept where the reinforced concrete skins take compressive and tensile loads resulting in higher stiffness and strength and the core transfers shear loads between the faces. This research uses structural software Strand7, which is based on finite element method, to predict the load deformation behaviour of the CEPS sandwich slab panels. Non linear static analysis was used in the numerical investigations. Predicted results were compared with the existing experimental results to validate the numerical approach used
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