Transferring Unit Cell Based Tissue Scaffold Design to Solid Freeform Fabrication

Designing for the freeform fabrication of heterogeneous tissue scaffold is always a challenge in Computer Aided Tissue Engineering. The difficulties stem from two major sources: 1) limitations in current CAD systems to assembly unit cells as building blocks to form complex tissue scaffolds, and 2) the inability to generate tool paths for freeform fabrication of unit cell assemblies. To overcome these difficulties, we have developed an abstract model based on skeletal representation and associated computational methods to assemble unit cells into an optimized structure. Additionally we have developed a process planning technique based on internal architecture pattern of unit cells to generate tool paths for freeform fabrication of tissue scaffold. By modifying our optimization process, we are able to transfer an optimized design to our fabrication system via our process planning technique.Mechanical Engineerin

Cohomology of Toroidal Orbifold Quotients

Let $\phi:\Z/p\to GL_{n}(\Z)$ denote an integral representation of the cyclic group of prime order $p$. This induces a $\Z/p$-action on the torus $X=\R^{n}/\Z^{n}$. The goal of this paper is to explicitly compute the cohomology groups $H^{*}(X/\Z/p;\Z)$ for any such representation. As a consequence we obtain an explicit calculation of the integral cohomology of the classifying space associated to the family of finite subgroups for any crystallographic group $\Gamma =\Z^n\rtimes\Z/p$ with prime holonomy.Comment: Final version. Accepted for publication in the Journal of Algebr

Classification Under Human Assistance

Most supervised learning models are trained for full automation. However, their predictions are sometimes worse than those by human experts on some specific instances. Motivated by this empirical observation, our goal is to design classifiers that are optimized to operate under different automation levels. More specifically, we focus on convex margin-based classifiers and first show that the problem is NP-hard. Then, we further show that, for support vector machines, the corresponding objective function can be expressed as the difference of two functions f = g - c, where g is monotone, non-negative and {\gamma}-weakly submodular, and c is non-negative and modular. This representation allows a recently introduced deterministic greedy algorithm, as well as a more efficient randomized variant of the algorithm, to enjoy approximation guarantees at solving the problem. Experiments on synthetic and real-world data from several applications in medical diagnosis illustrate our theoretical findings and demonstrate that, under human assistance, supervised learning models trained to operate under different automation levels can outperform those trained for full automation as well as humans operating alone

Optimizing Energy Transduction of Fluctuating Signals with Nanofluidic Diodes and Load Capacitors

This is the peer reviewed version of the following article: Ramirez Hoyos, P.; Cervera Montesinos, J.; Gómez Lozano, V.; Ali, M.; Nasir, S.; Ensinger, W.; Mafé, S. (2018). Optimizing Energy Transduction of Fluctuating Signals with Nanofluidic Diodes and Load Capacitors. Small. 14(18). doi:10.1002/smll.201702252, which has been published in final form at http://doi.org/10.1002/smll.201702252. This article may be used for non-commercial purposes in accordance with Wiley Terms and Conditions for Self-Archiving."[EN] The design and experimental implementation of hybrid circuits is considered allowing charge transfer and energy conversion between nanofluidic diodes in aqueous ionic solutions and conventional electronic elements such as capacitors. The fundamental concepts involved are reviewed for the case of fluctuating zero-average external potentials acting on single pore and multipore membranes. This problem is relevant to electrochemical energy conversion and storage, the stimulus-response characteristics of nanosensors and actuators, and the estimation of the accumulative effects caused by external signals on biological ion channels. Half-wave and full-wave voltage doublers and quadruplers can scale up the transduction between ionic and electronic signals. The network designs discussed here should be useful to convert the weak signals characteristic of the micro and nanoscale into robust electronic responses by interconnecting iontronics and electronic elements.P.R., J.C., V.G., and S.M. acknowledge the financial support from the Ministry of Economy and Competitiveness of Spain, (Materials Program, project No. MAT2015-65011-P), and FEDER. M.A., S.N., and W.E. acknowledge the funding from the Hessen State Ministry of Higher Education, Research and the Arts, Germany, under the LOEWE project iNAPO.Ramirez Hoyos, P.; Cervera Montesinos, J.; Gómez Lozano, V.; Ali, M.; Nasir, S.; Ensinger, W.; Mafé, S. (2018). Optimizing Energy Transduction of Fluctuating Signals with Nanofluidic Diodes and Load Capacitors. Small. 14(18). https://doi.org/10.1002/smll.201702252S1418Misra, N., Martinez, J. A., Huang, S.-C. J., Wang, Y., Stroeve, P., Grigoropoulos, C. P., & Noy, A. (2009). Bioelectronic silicon nanowire devices using functional membrane proteins. Proceedings of the National Academy of Sciences, 106(33), 13780-13784. doi:10.1073/pnas.0904850106Lemay, S. G. (2009). Nanopore-Based Biosensors: The Interface between Ionics and Electronics. ACS Nano, 3(4), 775-779. doi:10.1021/nn900336jTybrandt, K., Larsson, K. C., Richter-Dahlfors, A., & Berggren, M. (2010). Ion bipolar junction transistors. Proceedings of the National Academy of Sciences, 107(22), 9929-9932. doi:10.1073/pnas.0913911107Duan, X., Fu, T.-M., Liu, J., & Lieber, C. M. (2013). Nanoelectronics-biology frontier: From nanoscopic probes for action potential recording in live cells to three-dimensional cyborg tissues. Nano Today, 8(4), 351-373. doi:10.1016/j.nantod.2013.05.001Ramirez, P., Cervera, J., Ali, M., Ensinger, W., & Mafe, S. (2014). Logic Functions with Stimuli-Responsive Single Nanopores. ChemElectroChem, 1(4), 698-705. doi:10.1002/celc.201300255Guan, W., Li, S. X., & Reed, M. A. (2014). Voltage gated ion and molecule transport in engineered nanochannels: theory, fabrication and applications. Nanotechnology, 25(12), 122001. doi:10.1088/0957-4484/25/12/122001Tagliazucchi, M., & Szleifer, I. (2015). Transport mechanisms in nanopores and nanochannels: can we mimic nature? Materials Today, 18(3), 131-142. doi:10.1016/j.mattod.2014.10.020Ramirez, P., Gomez, V., Ali, M., Ensinger, W., & Mafe, S. (2013). Net currents obtained from zero-average potentials in single amphoteric nanopores. Electrochemistry Communications, 31, 137-140. doi:10.1016/j.elecom.2013.03.026Gomez, V., Ramirez, P., Cervera, J., Nasir, S., Ali, M., Ensinger, W., & Mafe, S. (2015). Converting external potential fluctuations into nonzero time-average electric currents using a single nanopore. Applied Physics Letters, 106(7), 073701. doi:10.1063/1.4909532Gomez, V., Ramirez, P., Cervera, J., Nasir, S., Ali, M., Ensinger, W., & Mafe, S. (2015). Charging a Capacitor from an External Fluctuating Potential using a Single Conical Nanopore. Scientific Reports, 5(1). doi:10.1038/srep09501Queralt-Martín, M., García-Giménez, E., Aguilella, V. M., Ramirez, P., Mafe, S., & Alcaraz, A. (2013). Electrical pumping of potassium ions against an external concentration gradient in a biological ion channel. Applied Physics Letters, 103(4), 043707. doi:10.1063/1.4816748Verdia-Baguena, C., Gomez, V., Cervera, J., Ramirez, P., & Mafe, S. (2017). Energy transduction and signal averaging of fluctuating electric fields by a single protein ion channel. Physical Chemistry Chemical Physics, 19(1), 292-296. doi:10.1039/c6cp06035hGomez, V., Cervera, J., Nasir, S., Ali, M., Ensinger, W., Mafe, S., & Ramirez, P. (2016). Electrical network of nanofluidic diodes in electrolyte solutions: Connectivity and coupling to electronic elements. Electrochemistry Communications, 62, 29-33. doi:10.1016/j.elecom.2015.10.022Ramirez, P., Gomez, V., Verdia-Baguena, C., Nasir, S., Ali, M., Ensinger, W., & Mafe, S. (2016). Designing voltage multipliers with nanofluidic diodes immersed in aqueous salt solutions. Physical Chemistry Chemical Physics, 18(5), 3995-3999. doi:10.1039/c5cp07203dRamirez, P., Gomez, V., Cervera, J., Nasir, S., Ali, M., Ensinger, W., … Mafe, S. (2016). Voltage-controlled current loops with nanofluidic diodes electrically coupled to solid state capacitors. RSC Advances, 6(60), 54742-54746. doi:10.1039/c6ra08277gRamirez, P., Garcia-Morales, V., Gomez, V., Ali, M., Nasir, S., Ensinger, W., & Mafe, S. (2017). Hybrid Circuits with Nanofluidic Diodes and Load Capacitors. Physical Review Applied, 7(6). doi:10.1103/physrevapplied.7.064035Ramirez, P., Gomez, V., Cervera, J., Nasir, S., Ali, M., Ensinger, W., & Mafe, S. (2015). Energy conversion from external fluctuating signals based on asymmetric nanopores. Nano Energy, 16, 375-382. doi:10.1016/j.nanoen.2015.07.013Hou, Y., Vidu, R., & Stroeve, P. (2011). Solar Energy Storage Methods. Industrial & Engineering Chemistry Research, 50(15), 8954-8964. doi:10.1021/ie2003413Ali, M., Ahmed, I., Ramirez, P., Nasir, S., Mafe, S., Niemeyer, C. M., & Ensinger, W. (2017). A redox-sensitive nanofluidic diode based on nicotinamide-modified asymmetric nanopores. Sensors and Actuators B: Chemical, 240, 895-902. doi:10.1016/j.snb.2016.09.061Zhang, Y., & Schatz, G. C. (2017). Conical Nanopores for Efficient Ion Pumping and Desalination. The Journal of Physical Chemistry Letters, 8(13), 2842-2848. doi:10.1021/acs.jpclett.7b01137Apel, P. (2001). Track etching technique in membrane technology. Radiation Measurements, 34(1-6), 559-566. doi:10.1016/s1350-4487(01)00228-1Siwy, Z., Trofin, L., Kohli, P., Baker, L. A., Trautmann, C., & Martin, C. R. (2005). Protein Biosensors Based on Biofunctionalized Conical Gold Nanotubes. Journal of the American Chemical Society, 127(14), 5000-5001. doi:10.1021/ja043910fRamirez, P., Ali, M., Ensinger, W., & Mafe, S. (2012). Information processing with a single multifunctional nanofluidic diode. Applied Physics Letters, 101(13), 133108. doi:10.1063/1.4754845Cervera, J., Ramirez, P., Gomez, V., Nasir, S., Ali, M., Ensinger, W., … Mafe, S. (2016). Multipore membranes with nanofluidic diodes allowing multifunctional rectification and logical responses. Applied Physics Letters, 108(25), 253701. doi:10.1063/1.4954764Nasir, S., Ramirez, P., Ali, M., Ahmed, I., Fruk, L., Mafe, S., & Ensinger, W. (2013). Nernst-Planck model of photo-triggered, pH–tunable ionic transport through nanopores functionalized with «caged» lysine chains. The Journal of Chemical Physics, 138(3), 034709. doi:10.1063/1.4775811Pérez-Mitta, G., Albesa, A. G., Trautmann, C., Toimil-Molares, M. E., & Azzaroni, O. (2017). Bioinspired integrated nanosystems based on solid-state nanopores: «iontronic» transduction of biological, chemical and physical stimuli. Chemical Science, 8(2), 890-913. doi:10.1039/c6sc04255dGuo, W., Cao, L., Xia, J., Nie, F.-Q., Ma, W., Xue, J., … Jiang, L. (2010). Energy Harvesting with Single-Ion-Selective Nanopores: A Concentration-Gradient-Driven Nanofluidic Power Source. Advanced Functional Materials, 20(8), 1339-1344. doi:10.1002/adfm.200902312Roseman, J. M., Lin, J., Ramakrishnan, S., Rosenstein, J. K., & Shepard, K. L. (2015). Hybrid integrated biological–solid-state system powered with adenosine triphosphate. Nature Communications, 6(1). doi:10.1038/ncomms10070Kocer, A., Tauk, L., & Déjardin, P. (2012). Nanopore sensors: From hybrid to abiotic systems. Biosensors and Bioelectronics, 38(1), 1-10. doi:10.1016/j.bios.2012.05.013Maglia, G., Heron, A. J., Hwang, W. L., Holden, M. A., Mikhailova, E., Li, Q., … Bayley, H. (2009). Droplet networks with incorporated protein diodes show collective properties. Nature Nanotechnology, 4(7), 437-440. doi:10.1038/nnano.2009.121Han, J.-H., Kim, K. B., Kim, H. C., & Chung, T. D. (2009). Ionic Circuits Based on Polyelectrolyte Diodes on a Microchip. Angewandte Chemie International Edition, 48(21), 3830-3833. doi:10.1002/anie.200900045Ali, M., Ramirez, P., Nguyen, H. Q., Nasir, S., Cervera, J., Mafe, S., & Ensinger, W. (2012). Single Cigar-Shaped Nanopores Functionalized with Amphoteric Amino Acid Chains: Experimental and Theoretical Characterization. ACS Nano, 6(4), 3631-3640. doi:10.1021/nn3010119Vlassiouk, I., & Siwy, Z. S. (2007). Nanofluidic Diode. Nano Letters, 7(3), 552-556. doi:10.1021/nl062924bCervera, J., Ramirez, P., Mafe, S., & Stroeve, P. (2011). Asymmetric nanopore rectification for ion pumping, electrical power generation, and information processing applications. Electrochimica Acta, 56(12), 4504-4511. doi:10.1016/j.electacta.2011.02.056Ramírez, P., Rapp, H.-J., Mafé, S., & Bauer, B. (1994). Bipolar membranes under forward and reverse bias conditions. Theory vs. experiment. Journal of Electroanalytical Chemistry, 375(1-2), 101-108. doi:10.1016/0022-0728(94)03379-xHou, X., Guo, W., & Jiang, L. (2011). Biomimetic smart nanopores and nanochannels. Chemical Society Reviews, 40(5), 2385. doi:10.1039/c0cs00053aGuo, W., Tian, Y., & Jiang, L. (2013). Asymmetric Ion Transport through Ion-Channel-Mimetic Solid-State Nanopores. Accounts of Chemical Research, 46(12), 2834-2846. doi:10.1021/ar400024

Variational principles and finite element Bloch analysis in couple stress elastodynamics

We address the numerical simulation of periodic solids (phononic crystals) within the framework of couple stress elasticity. The additional terms in the elastic potential energy lead to dispersive behavior in shear waves, even in the absence of material periodicity. To study the bulk waves in these materials, we establish an action principle in the frequency domain and present a finite element formulation for the wave propagation problem related to couple stress theory subject to an extended set of Bloch-periodic boundary conditions. A major difference from the traditional finite element formulation for phononic crystals is the appearance of higher-order derivatives. We solve this problem with the use of a Lagrange-multiplier approach. After presenting the variational principle and general finite element treatment, we particularize it to the problem of finding dispersion relations in elastic bodies with periodic material properties. The resulting implementation is used to determine the dispersion curves for homogeneous and porous couple stress solids, in which the latter is found to exhibit an interesting bandgap structure.Comment: 29 pages, 8 figure