Cylindrical Compartments Research Articles

Blast resistance of multi-compartment structure subjected to the contact underwater explosion

In this paper, the underwater blast behavior of a multi-compartment protective system was numerically analyzed using AUTODYN. A group of structures composed of three circular metal plates and two cylindrical compartments in between were subjected to a contact underwater explosion (UNDEX). An experimental study was carried out to validate the numerical simulation model. Besides, a rigorous parametric study was conducted on structural geometry and its material variables using the full-factorial and response surface methods in DoE software. Later on, a multi-objective optimization was carried out on the obtained objective functions for the prediction of the Central Deflection of the backplate (CentD) and Energy Absorption per Areal Mass (EApM). The proposed optimal condition was also validated using the numerical simulation model. It was found that using the arrangement of Al2024-T3, St37, and St37 as the faceplate, midplate, and backplate in a configuration as well as mediums of water and air in-between outperforms in terms of minimum CentD and maximum EApM. Using the same mediums in compartments regardless of type of layers leads to backplate tearing and structure failure. From the structural geometry point of view, it was found that variations of midplate thickness and fore compartment height have the most influence on CentD and EApM, respectively. Therefore, the suggested configuration can be successfully used as a marine armor with dimensional considerations under contact underwater explosion.

The Influence of the Angular Dimension of Rectangular Cutouts on the Stress and Strain State of Sandwich Cylindrical Compartments

The Influence of the Angular Dimension of Rectangular Cutouts on the Stress and Strain State of Sandwich Cylindrical Compartments

Liquid crystal microcapillary-based sensors for affordable analytical applications.

Stimuli-responsive properties of liquid crystals (LCs), when combined with their optical properties, offer sensitive and rapid sensing applications. Here, we propose and demonstrate a microcapillary-based method to be applied for the online detection of amphiphilic species, which can be further used for tracking biological and chemical species in aqueous media. Specifically, we used compartments (300-1400 μm) of nematic 4-cyano-4'-pentylbiphenyl (5CB) that were positioned into cylindrical glass microcapillaries that promote homeotropic anchoring. The flat surfaces of the cylindrical LC compartments were in contact with an aqueous media. We characterized the equilibrium and nonequilibrium response of LCs upon a change in their anchoring at the aqueous interfaces. Upon anchoring transition, we observed the formation of a positively charged defect at the proximity of the interface that moved to the center of the LC compartment and reached equilibrium, a four-petal configuration. This transition was observed to take an average of 41 ± 19 min., which we related to the motion of the defect due to the imbalance of the elastic forces. During the transition, we observed metastable states which could be removed via thermal treatment. We showed the capillary sensors to be useful considering their ease of additional quantification. We also show that the sensors are reversible that facilitate temporal and cumulative quantification. The findings reported in this study can further be used to develop sensors for specific purposes that require continuous tracking of the chemical and biological species that is critical for the health and safety of the individuals and society.

Tracing the origin of hair follicle stem cells.

Tissue stem cells are generated from a population of embryonic progenitors through organ-specific morphogenetic events1,2. Although tissue stem cells are central to organ homeostasis and regeneration, it remains unclear how they are induced during development, mainly because of the lack of markers that exclusively label prospective stem cells. Here we combine marker-independent long-term 3D live imaging and single-cell transcriptomics to capture a dynamic lineage progression and transcriptome changes in the entire epithelium of the mouse hair follicle as it develops. We found that the precursors of different epithelial lineages were aligned in a 2D concentric manner in the basal layer of the hair placode. Each concentric ring acquired unique transcriptomes and extended to form longitudinally aligned, 3D cylindrical compartments. Prospective bulge stem cells were derived from the peripheral ring of the placodebasal layer, but not from suprabasal cells (as was previously suggested3). The fate of placode cells is determined by the cell position, rather than by the orientation of cell division.We also identified 13gene clusters: the ensemble expression dynamics of these clusters drew the entire transcriptional landscape of epithelial lineage diversification, consistent with cell lineage data. Combining these findings with previous work on the development of appendages in insects4,5, we describe the 'telescope model', a generalized model for the development of ectodermal organs in which 2D concentric zones in the placode telescope out to form 3D longitudinally aligned cylindrical compartments.

Multi-component modeling and simulation of a new photoelectrochemical reactor design for clean hydrogen production

A novel photoelectrochemical cell design to make a unique reactor is developed and investigated to improve solar to hydrogen conversion efficiency and increase the hydrogen evolution rate. A dome-type photocathode and a circular disc anode are immersed in an alkaline electrolyte of potassium hydroxide in two cylindrical compartments. This new reactor design concerns utilizing the maximum sunlight during the daytime due to the dome shape and increasing the photocathode active area. Four different types of analyses and simulations, including energy, exergy, electrochemical and fluid flow, are performed to investigate the present hydrogen reactor performance using both Engineering Equation Solver and COMSOL software packages. Thermodynamic and electrochemical equations are solved, including mass, energy, entropy, and exergy balance equations, as well as the electrochemical equations. The proposed flow circulation shows a significant effect to avoid the hydrogen bubble coverage phenomenon. The influences of varying the illumined photocathode surface area, the solar irradiance flux, and the quantum efficiency are studied on the hydrogen evolution rate and the solar to hydrogen efficiency. The present hydrogen generation rate and the overall energy system efficiency are 42.1 μg/s, 4.9%, respectively, occurring at solar irradiance of 600 W/m2 and the illumined area of 840 cm2. The highest hydrogen evolution rate is 60.20 μg/s achieved at the illumined photocathode area of 1200 cm2. The maximum reactor energy efficiency found to be 6.52% occurred at a quantum efficiency of 20%, respectively. The study results further confirm that increasing the illuminated photocathode area increases the solar to hydrogen energy efficiency and the hydrogen production rates. Moreover, the hydrogen production rates increase with an increase in the solar irradiance.

A study on energy and fluid flows for a novel photoelectrochemical reactor developed for hydrogen production

A numerical study of a new photoelectrochemical (PEC) cell for hydrogen production is performed to investigate energy and fluid flows in particularly removing the adhering bubbles on the surface of the electrodes. The proposed ratio of the electrodes’ surface area is taken as 2.6:1 of the photocathode to the anode. The total surface area of the dome photoelectrode and the disc anode is designed to be 1680.2 cm2 and 645.4 cm2. The developed reactor primarily consists of two cylindrical compartments made of acrylic glass with good absorptivity to allow the maximum wavelengths to pass through. The sunlight is supplied from a solar simulator on the top cover of the PEC cell. The governing equations of the proposed model include Navier-Stokes equations, energy equation, and the radiative transfer equation (RTE). The COMSOL package is used to perform the fluid flow simulation for two different models. Two different COMSOL modules are utilized to solve the governing equations, including Laminar flow and heat transfer in solids and fluids. Also, all electrochemical equations are investigated by the Engineering Equation Solver (EES). The velocity contours, streamlines, temperature contours, and pressure lines are presented and discussed. The present results indicate that the electrolysis and solar to hydrogen (STH) efficiencies are found to be 26.70% and 5.17%, with a mass flow of hydrogen at 66.3 × 10−9 kg/s. A comprehensive parametric study is performed to find the best-operating conditions of the studied PEC reactor. Furthermore, the highest STH efficiency is obtained as 7.3% at a solar incident flux of 400 W/m2. The hydrogen mass production rate can be generated of 132.7 × 10−9 kg/s at a solar incident flux of 1200 W/m2.

Comprehensive Biomechanism of Impact Resistance in the Cat's Paw Pad.

Cats are able to jump from a high-rise without any sign of injury, which is attributed in large part to their impact-resistant paw pads. The biomechanical study of paw pads may therefore contribute to improving the impact resistance of specific biomimetic materials. The present study is aimed at investigating the mechanics of the paw pads, revealing their impact-resistant biomechanism from macro- and microscopic perspectives. Histological and micro-CT scanning methods were exploited to analyze the microstructure of the pads, and mechanical testing was conducted to observe the macroscopic mechanical properties at different loading frequencies. Numerical micromodels of the ellipsoidal and cylindrical adipose compartments were developed to evaluate the mechanical functionality as compressive actions. The results show that the stiffness of the pad increases roughly in proportion to strain and mechanical properties are almost impervious to strain rate. Furthermore, the adipose compartment, which comprises adipose tissue enclosed within collagen septa, in the subcutaneous tissue presents an ellipsoid-like structure, with a decreasing area from the middle to the two ends. Additionally, the finite element results show that the ellipsoidal structure has larger displacement in the early stage of impact, which can absorb more energy and prevent instability at touchdown, while the cylindrical structure is more resistant to deformation. Moreover, the Von Mises of the ellipsoidal compartment decrease gradually from both ends to the middle, making it change to a cylindrical shape, and this may be the reason why the macroscopic stiffness increases with increasing time after contact. This preliminary investigation represents the basis for biomechanical interpretation and can accordingly provide new inspirations of shock-absorbing composite materials in engineering.

Experimental Strength Analysis of Variable Stiffness Waffel-Grid Cylindrical Compartments. Part 2. Analysis Results

Experimental Strength Analysis of Variable Stiffness Waffel-Grid Cylindrical Compartments. Part 2. Analysis Results

ДО РОЗРАХУНКУ НА СТІЙКІСТЬ КОМБІНОВАНОЇ ОБОЛОНКОВОЇ КОНСТРУКЦІЇ З УРАХУВАННЯМ ДИСКРЕТНОСТІ РОЗТАШУВАННЯ ПРОМІЖНИХ ШПАНГОУТІВ

Вивчається стійкість навантаженої зовнішнім тиском оболонкової конструкції, що складається з спряжених циліндричних та конічних відсіків, підкріплених дискретно розташованими шпангоутами. Циліндричні відсіки обираються постійної товщини, конічні – лінійно змінної. Стійкість складеної підкріпленої конструкції і окремих її частин визначається за допомогою матричного методу. Особлива увага приділяється пошуку параметрів рівностійких прольотів підкріпленої конструкції, в тому числі підбору раціональних жорсткостей шпангоутів, що забезпечують рівностійкість локальних і загальних (з захватом шпангоутів) форм випинання. Вивчаються конструкції з різними параметрами.

Experimental Strength Analysis of Variable Stiffness Waffel-Grid Cylindrical Compartments. Part 1. Experimental Procedure

Experimental Strength Analysis of Variable Stiffness Waffel-Grid Cylindrical Compartments. Part 1. Experimental Procedure

Влияние вырезов на прочность цилиндрических отсеков ракет-носителей при неупругом деформировании материала

Влияние вырезов на прочность цилиндрических отсеков ракет-носителей при неупругом деформировании материала

Can we detect the effect of spines and leaflets on the diffusion of brain intracellular metabolites?

Prior models used to clarify which aspects of tissue microstructure mostly affect intracellular diffusion and corresponding diffusion-weighted magnetic resonance (DW-MR) signal have focused on relatively simple geometrical descriptions of the cellular microenvironment (spheres, randomly oriented cylinders, etc…), neglecting finer morphological details which may have an important role. Some types of neurons present high density of spines; and astrocytes and macroglial cells processes present leaflets, which may all impact the diffusion process. Here, we use Monte-Carlo simulations of many particles diffusing in cylindrical compartments with secondary structures mimicking spines and leaflets of neuronal and glial cell fibers, to investigate to what extent the diffusion-weighted signal of intracellular molecules is sensitive to spines/leaflets density and length. In order to study the specificity of DW-MR signal to these kinds of secondary structures, beading-like geometry is simulated as "control" deviation from smooth cylinder too. Results suggest that: a) the estimated intracellular tortuosity increases as spines/leaflets density or length (beading amplitude) increase; b) the tortuosity limit is reached for diffusion time td>200 ms for metabolites and td>70 ms for water molecules, suggesting that the effects of these finer morphological details are negligible at td longer than these threshold values; c) fiber diameter is overestimated, while intracellular diffusivity is underestimated, when simple geometrical models based on hollow smooth cylinders are used; d) apparent surface-to-volume, S/V, ratio estimated by linear fit of high frequency OG data appears to be an excellent estimation of the actual S/V ratio, even in the presence of secondary structures, and it increases as spines and leaflets density or length increase (while decreasing as beadings amplitude increases). Comparison between numerical simulations and multimodal metabolites DW-MRS experiments in vivo in mouse brain shows that these fine structures may affect the DW-MRS signal and the derived diffusion metrics consistently with their expected density and geometrical features.This work suggests that finer structures of cell morphology have non-negligible effects on intracellular molecules’ diffusion that may be measured by using multimodal DW-MRS approaches, stimulating future developments and applications.

Simulation Of The Electrical Field Generated By Bipolar And Ganglion Cells In The Electrically Stimulated Retina

Event Abstract Back to Event Simulation Of The Electrical Field Generated By Bipolar And Ganglion Cells In The Electrically Stimulated Retina Paul Werginz1* and Frank Rattay1 1 Vienna University of Technology, Institute for Analysis and Scientific Computing, Austria Motivation Recording of the (summed) response of bipolar (BCs) and ganglion cells (GCs) is essential for examination of cell activation in in-vitro experiments in order to gain a better understanding of the electrically stimulated retina. Here, we describe a proof of concept to simulate these electrical fields during extracellular stimulation. Material and Methods The response of BCs and GCs to extracellular electrical stimulation is computed with multi-compartment models. Our modeling discretizes a simplified 2-D cell geometry in space, using cylindrical and spherical compartments. Current flow between compartments and across the cell membrane leads to a system of ordinary differential equations (Eq. 1 [1]). Ionic currents are computed with a Hodgkin-Huxley-like model approach for 35 degree Celsius [2]. Here the extracellular field generated by a stimulating electrode is computed by a simple analytical solution for point sources in homogeneous media (Eq. 2) Extracellular recordings were computed with the same formula; see [3] for details. The used model of the ribbon synapse at BC terminals is presented in [4]. Eq. 1 Eq. 2 Results A single extracellular action potential is bi- or triphasic, depending on the position of the recording electrode and the site of spike initiation. For direct GC stimulation recordings at or close to the soma resulted in biphasic waveforms whereas recordings at the distal axon resulted in triphasic waveforms (Fig. 1). Additionally, the amplitude of the recorded waveforms varies upon the location of the recording electrode, the geometric properties of the model neuron (e.g. fiber diameter in Fig. 1B) and ion channel equipment along the neural membrane. When BC input was fed to the model GC bursts of action potentials were generated and in the extracellular recording the synaptic input could be displayed (Fig. 2). Calcium currents that drive the synaptic signaling cascade in BC terminal compartments, however, could not be revealed because of the stimulus artifact. Discussion Direct stimulation of GCs from the epiretinal space generated responses that are qualitatively similar to data obtained in in-vitro experiments [5]. Periodic synaptic input during repetitive stimulation led to bursting spiking activity in GCs. Applied stimulus amplitudes resulted in synaptic (indirect) activation whereas no direct GC spikes were generated. The spiking rate is decreased for later pulses because of vesicle depletion in the ribbon synapses. Recorded intra- and extracellular responses revealed the synaptic inputs, however, the signal was rather small in the extracellular recording. Conclusion The presented initial modeling study shows that it is generally feasible to simulate the extracellular field generated by retinal neurons during electrical stimulation.

Adsorbents/ion exchangers-PVA blend membranes: Preparation, characterization and performance for the removal of Zn2+ by electrodialysis

The present paper was aimed at studying the possibility of zinc (Zn) removal from the wastewater discharged from zinc electroplating processes. In order to save industrial and environmental resources, the concentrated solution could be reused after electrodialysis process. A mini-electrodialysis system with three cylindrical compartments and different membranes containing various resins (Purolite A500 and Hypersol-Macronet MN500) was employed, which can be further applied for the treatment of synthetic effluent which contained zinc ions. The electrodialysis system was operated at constant voltage using different concentrations of synthetic solutions of zinc ions, without and with electrolyte recirculation for 1.5h. The pH and conductivity of solutions were measured before and after the electrodialysis process occurs. Also the removal ratio (Rr) and mass flow (J) of zinc ions, energy consumption (EC) and current efficiency (CE) were determined. It was found that electrodialysis treatment generated a very low conductivity solution, enabling its reuse as rinse water. According to the obtained results when using a membrane pair with higher ion exchange capacity (IEC) the removal ratio is improved (over 80%). The physico-chemical, structural and mechanical properties of prepared membranes were registered, before and after electrodialysis process takes place, by means of complementary analytical techniques, namely, ion-exchange capacity, water content and thickness measurements. Furthermore analysis were also carried out by Fourier transform infrared spectroscopy (FT-IR), environmental scanning electron microscopy (ESEM), thermal gravimetric analysis (TGA) and electrochemical impedance spectroscopy (EIS).

TU‐C‐12A‐07: Characterization of Longitudinal Reproducibility of Quantitative Diffusion Imaging Data Acquired with Four Different Protocols Using a Phantom

Purpose:To characterize and compare the longitudinal reproducibility of diffusion imaging data acquired with four different protocols using a phantom.Methods:The Diffusive Quantitative Imaging Phantom (DQIP) was constructed using fifteen cylindrical compartments within a larger compartment, filled with deionized water doped with CuSO4 and NaCl. The smaller compartments contained arrays of hexagonal or cylindrical glass capillaries of varying inner diameters, for differing restraint of water diffusion. The sensitivity of diffusion imaging metrics to signal‐to‐noise ratio (SNR) was probed by doping compartments with differing ratios of deuterium oxide to H2O. A cork phantom enclosure was constructed to increase thermal stability during scanning and a cork holder was made to reproduce scanner positioning. Four different protocols of DWI (diffusion weighted imaging) and DTI (Diffusion tensor imaging) imaging were assembled on a GE Excite HDx 3.0T MRI scanner to collect imaging data over 9‐10 days. Data was processed with in‐house software created in Matlab to obtain fractional anisotropy (FA) and apparent diffusion coefficient (ADC) values.Results:All DTI and DWI sequences showed good longitudinal stability of mean FA and ADC values per compartment, exhibiting low standard deviation ∼9%. A t‐test was performed to compare mean FA values from the DTI clinical protocol to those of the DTI special protocol, indicating significantly different values in the majority of compartments. ANOVA performed on ADC values for all DTI and DWI sequences also showed significantly different values in a majority of compartments.Conclusion:This work has the potential for quantifying systemic variations between diffusion imaging sequences from different platforms. Characterization of DWI and DTI performance were done over four sequences with predictable results. This data suggests that the DQIP phantom may be a reliable method of monitoring day‐to‐day and scan‐to‐scan variation in diffusion imaging sequences from different platforms.Schott Glass North America and The Phantom Laboratory have donated materials and personnel time to this project.

MO‐G‐18C‐09: Thermal Characterization and Initial Imaging Results From the Diffusive Quantitative Imaging Phantom (DQIP)

Purpose:The goals of this project were a) to characterize thermal relaxation of the phantom and b) to demonstrate correlations between temperature, signal‐to‐noise ratio (SNR) and diffusion tensor imaging (DTI) metrics. A site‐based clinical DTI protocol was used in this study. The hypothesis is that thermal stability of the phantom will be adequate such that temperature monitoring during a scan may be neglected.Methods:The Diffusive Quantitative Imaging Phantom (DQIP) is a prototype phantom consisting of fifteen cylindrical compartments containing capillary arrays, encased in a larger compartment. Thermal stability of the phantom was established using a cork container and a Peltier incubator. After the phantom was cooled or heated, thermal relaxation was measured as the phantom was allowed to return to room temperature, with and without cork. A clinical‐grade DTI protocol was used to collect scan and temperaturedependent data from the phantom over ten days. SNR and thermal dependences of fractional anisotropy (FA) and apparent diffusion coefficient (ADC) were characterized by scanning a heated or cooled phantom over several hours.Results:The phantom temperature was stable within ±0.08°C/hour per degree difference from the scan room using the cork enclosure, compared to ±0.3°C/hour per degree difference without the cork enclosure. During scanning, temperature variation was ∼ 0.1°C/hour. The dependences of (FA, ADC) on (SNR, temperature) were characterized for the heating and cooling experiments. However, for the range of temperature (1.2°C) and SNR (max: ±77%) variations in a particular compartment over all daily measurements, no significant improvement in total variation was achieved after regressing out temperature and SNR, although one compartment showed significant decline after regression.Conclusion:Thermal stability of the DQIP phantom and incubator system is sufficient for neglecting temperature variations during scanning. For a standard clinical protocol, SNR dependence of FA and ADC are not sufficient to warrant correction.Schott Glass North America and The Phantom Laboratory have donated materials and personnel time to this project.

Estimation method for biophysical properties of insect neurons in the combination of suitable stimulation and multi-compartment simulation with supercomputers

Event Abstract Back to Event Estimation method for biophysical properties of insect neurons in the combination of suitable stimulation and multi-compartment simulation with supercomputers Daisuke Miyamoto1*, Tomoki Kazawa2, Stephan Haupt2, Masashi Tabuchi3, Tomoaki Mori1, Kei Nakatani4 and Ryohei Kanzaki2 1 Graduate School of Information Science and Technology, The University of Tokyo , Japan 2 Research Center for Advanced Science and Technology, The University of Tokyo , Japan 3 Graduate School of Engineering, The University of Tokyo , Japan 4 Graduate School of Life and Environmental Science, Tsukuba University , Japan The importance of local dendritic activicty in information processing of single neurons has been generally recognized. Constructing multi-compartment simulation models that also reflect the distribution of active conductances in real neurons is the one of the big challenges to achieve realistic modeling due to the paucity of experimental data. As a remedy to this problem, we propose an estimation method combining suitable electrical stimulation and massively parallel computation using genetic algorithms. We applied this method to projection neurons in antennal lobes of silkmoth (Bombyx mori) as the first model neurons. We obtained morphological tree models containing about 4,000 cylindrical compartments from confocal microscopy images. We assumed the presence of known insect K+, Na+ and Ca2+ channels and used candidate distribution models to estimate the corresponding conductances. Several types of electrical stimuli (current ramps, optionally with added sine waves of different frequencies, and voltage clamp pulses) stimuli, were evaluated for their efficiency in providing multi-compartment models reproducing the electrophysiological data. Such estimation methods need to run multi-compartment simulations many times. To meet the computational demands of the method, we used the Real Coded Genetics Algorithm (RCGA) for parallel efficiency and MPI/OpenMP hybrid implementations on the K computer which has 640,000 SPARC64VIIIfx CPU cores and on the RIKEN Integrated Cluster of Clusters (RICC).For estimating the position of a high-conductance area in an axon, injecting a current ramp with added sine wave showed good performance even after a small number of generations of the genetic algorithm (Fig. 1). This could be related to the frequency transmission characteristics of the axon. With 32,768 genes and 200 generations per estimation, we achieved parallel efficiency as high as p=0.99987 comparing the 1,024 cores and 8,192 cores cases (Fig. 2). We showed here that 1) RCGA is suitable for estimating biophysical properties for realistic multi-compartment models with high efficiency in massively parallel computation and that 2) suitable choice of stimulation paradigms can improve the efficiency of estimation. The interaction between experimental data simulation and parameter estimation can be a useful tool to improve multi-compartment models. Figure 1 Keywords: computational neuroscience, Biophysical methods, neuron models, supercomputer simulation, genetic algorithms Conference: 5th INCF Congress of Neuroinformatics, Munich, Germany, 10 Sep - 12 Sep, 2012. Presentation Type: Poster Topic: Neuroinformatics Citation: Miyamoto D, Kazawa T, Haupt S, Tabuchi M, Mori T, Nakatani K and Kanzaki R (2014). Estimation method for biophysical properties of insect neurons in the combination of suitable stimulation and multi-compartment simulation with supercomputers. Front. Neuroinform. Conference Abstract: 5th INCF Congress of Neuroinformatics. doi: 10.3389/conf.fninf.2014.08.00011 Copyright: The abstracts in this collection have not been subject to any Frontiers peer review or checks, and are not endorsed by Frontiers. They are made available through the Frontiers publishing platform as a service to conference organizers and presenters. The copyright in the individual abstracts is owned by the author of each abstract or his/her employer unless otherwise stated. Each abstract, as well as the collection of abstracts, are published under a Creative Commons CC-BY 4.0 (attribution) licence (https://creativecommons.org/licenses/by/4.0/) and may thus be reproduced, translated, adapted and be the subject of derivative works provided the authors and Frontiers are attributed. For Frontiers’ terms and conditions please see https://www.frontiersin.org/legal/terms-and-conditions. Received: 21 Mar 2013; Published Online: 27 Feb 2014. * Correspondence: Dr. Daisuke Miyamoto, Graduate School of Information Science and Technology, The University of Tokyo, Meguro-ku, Japan, miyamoto@brain.imi.i.u-tokyo.ac.jp Login Required This action requires you to be registered with Frontiers and logged in. To register or login click here. Abstract Info Abstract The Authors in Frontiers Daisuke Miyamoto Tomoki Kazawa Stephan Haupt Masashi Tabuchi Tomoaki Mori Kei Nakatani Ryohei Kanzaki Google Daisuke Miyamoto Tomoki Kazawa Stephan Haupt Masashi Tabuchi Tomoaki Mori Kei Nakatani Ryohei Kanzaki Google Scholar Daisuke Miyamoto Tomoki Kazawa Stephan Haupt Masashi Tabuchi Tomoaki Mori Kei Nakatani Ryohei Kanzaki PubMed Daisuke Miyamoto Tomoki Kazawa Stephan Haupt Masashi Tabuchi Tomoaki Mori Kei Nakatani Ryohei Kanzaki Related Article in Frontiers Google Scholar PubMed Abstract Close Back to top Javascript is disabled. 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Separating Attoliter-Sized Compartments Using Fluid Pore-Spanning Lipid Bilayers

Anodic aluminum oxide (AAO) is a porous material having aligned cylindrical compartments with 55-60 nm diameter pores, and being several micrometers deep. A protocol was developed to generate pore-spanning fluid lipid bilayers separating the attoliter-sized compartments of the nanoporous material from the bulk solution, while preserving the optical transparency of the AAO. The AAO was selectively functionalized by silane chemistry to spread giant unilamellar vesicles (GUVs) resulting in large continuous membrane patches covering the pores. Formation of fluid single lipid bilayers through GUV rupture could be readily observed by fluorescence microscopy and further supported by conservation of membrane surface area, before and after GUV rupture. Fluorescence recovery after photobleaching gave low immobile fractions (5-15%) and lipid diffusion coefficients similar to those found for bilayers on silica. The entrapment of molecules within the porous underlying cylindrical compartments, as well as the exclusion of macromolecules from the nanopores, demonstrate the barrier function of the pore-spanning membranes and could be investigated in three-dimensions using confocal laser scanning fluorescence imaging.

Driven diffusion in a periodically compartmentalized tube: homogeneity versus intermittency of particle motion.

We study the effect of a driving force F on drift and diffusion of a point Brownian particle in a tube formed by identical cylindrical compartments, which create periodic entropy barriers for the particle motion along the tube axis. The particle transport exhibits striking features: the effective mobility monotonically decreases with increasing F, and the effective diffusivity diverges as F→∞, which indicates that the entropic effects in diffusive transport are enhanced by the driving force. Our consideration is based on two different scenarios of the particle motion at small and large F, homogeneous and intermittent, respectively. The scenarios are deduced from the careful analysis of statistics of the particle transition times between neighboring openings. From this qualitative picture, the limiting small-F and large-F behaviors of the effective mobility and diffusivity are derived analytically. Brownian dynamics simulations are used to find these quantities at intermediate values of the driving force for various compartment lengths and opening radii. This work shows that the driving force may lead to qualitatively different anomalous transport features, depending on the geometry design.

Determination of effects of turbulence flow in a cathode environment on electricity generation using a tidal mud-based cylindrical-type sediment microbial fuel cell

We examined the possibility of harvesting electricity from the surface of a tidal mud flat using a cylindrical-type sediment microbial fuel cell (SMFC), a marine mud battery (MMB), which can be applied in a sea environment where the ebb and flow occur due to tidal difference. In addition, we indirectly investigated the influence of ebb and flow in a lab, using aeration, argon gassing, and by agitating the cathodic solution. The MMBs consisted of cylindrical acrylic compartments containing a nylon membrane, an anode, and a cathode in a single body. The MMBs were stuck vertically into an artificial tidal mud flat such that the anode electrode was in direct contact with the tidal mud surface. As a result, the maximum current and power density generated were 35 mA/m 2 and 9 mW/m 2, respectively, thus verifying that it is possible to harvest electricity from the surface of a tidal mud flat using an MMB without burying the anode electrode in the tidal mud. Furthermore, the results of tests using an artificial turbulence flow showed the flow induced by the tidal ebb and flow could allow the performance of MMBs to be enhanced.