Academic literature on the topic 'Single layer membranes'
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Journal articles on the topic "Single layer membranes"
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Loza, Sergey, Natalia Loza, Natalia Kutenko, and Nikita Smyshlyaev. "Profiled Ion-Exchange Membranes for Reverse and Conventional Electrodialysis." Membranes 12, no. 10 (October 11, 2022): 985. http://dx.doi.org/10.3390/membranes12100985.
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Profiled ion-exchange membranes are promising for improving the parameters of reverse electrodialysis due to the reduction of pumping power and electrical resistance. The smooth commercial heterogeneous cation-exchange MK-40 and anion-exchange MA-41 membranes were chosen as the initial membranes. Profiled membranes with three different types of surface profiles were obtained by hot pressing the initial membranes. The bilayer membranes were made on the basis of single-layer profiled membranes by casting MF-4SK film on the profiled surfaces. The diffusion permeability of all types of single-layer and bilayer profiled membranes was higher than of the initial ones due to the appearance of large defects on their surface during pressing. The conductivity of the profiled membrane was lower in the diluted solution and higher in the concentrated solution than of the initial one for all samples except for the bilayer anion-exchange membrane. The conductivity of that sample was lower than that of the initial anion-exchange MA-41 membrane over the entire range of studied concentrations. The counter-ion transport numbers for all studied membranes were calculated based on the concentration dependences of conductivity and diffusion permeability of the membrane by the microheterogeneous model. The selectivity of single layer and bilayer profiled membranes became lower after their profiling due to the increase of the solution phases of membranes. The asymmetry of the current-voltage curves for all single-layer and bilayer profiled membranes was found. The application of the single layer and bilayer profiled membranes in reverse electrodialysis did not lead to an increase in power density.
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Boztepe, Inci, Stephen Gray, Jianhua Zhang, and Jun-De Li. "Performance modelling of direct contact membrane distillation using a hydrophobic/hydrophilic dual-layer membrane." Journal of Water Reuse and Desalination 11, no. 3 (June 17, 2021): 490–507. http://dx.doi.org/10.2166/wrd.2021.072.
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Abstract HFP-co-PVDF/N6 hydrophobic/hydrophilic dual-layer membrane was used to study desalination with direct contact membrane distillation (DCMD). A one-dimensional (1-D) model was proposed to predict the flux and thermal efficiency. Heat and mass transfer equations were solved numerically for the combined hydrophilic and hydrophobic layers. The membrane characteristics of the hydrophobic layer were considered for the calculation of the mass transfer coefficients, while the hydrophilic layer was ignored since it was assumed to be filled with water. However, the hydrophilic layer was taken into account during the calculations of conductive heat transfer. Therefore, the equations are different, compared to single-layer hydrophobic membranes. It was found that with the same hydrophobic membrane characteristics, the single-layer membranes performed with better flux and thermal efficiency than the dual-layer membranes. Furthermore, the improvement of flux and thermal efficiency by an addition of the hydrophilic layer has not been observed experimentally, and it is suggested that the improved performance for dual-layer membranes reported previously is due to improved permeability by using thinner and more porous hydrophobic layers that can be mechanically reinforced by the hydrophilic layer. The validation of the model was conducted by comparing the experimental results for single- and dual-layer membranes with the modelling results. The predicted flux and thermal efficiency by the modelling were within 10% error to the experimental results.
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Niestroj-Pahl, Robert, Lara Stelmaszyk, Ibrahim M. A. ElSherbiny, Hussein Abuelgasim, Michaela Krug, Christian Staaks, Greta Birkholz, et al. "Performance of Layer-by-Layer-Modified Multibore® Ultrafiltration Capillary Membranes for Salt Retention and Removal of Antibiotic Resistance Genes." Membranes 10, no. 12 (December 6, 2020): 398. http://dx.doi.org/10.3390/membranes10120398.
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Polyether sulfone Multibore® ultrafiltration membranes were modified using polyelectrolyte multilayers via the layer-by-layer (LbL) technique in order to increase their rejection capabilities towards salts and antibiotic resistance genes. The modified capillary membranes were characterized to exhibit a molecular weight cut-off (at 90% rejection) of 384 Da. The zeta-potential at pH 7 was −40 mV. Laboratory tests using single-fiber modified membrane modules were performed to evaluate the removal of antibiotic resistance genes; the LbL-coated membranes were able to completely retain DNA fragments from 90 to 1500 nt in length. Furthermore, the pure water permeability and the retention of single inorganic salts, MgSO4, CaCl2 and NaCl, were measured using a mini-plant testing unit. The modified membranes had a retention of 80% toward MgSO4 and CaCl2 salts, and 23% in case of NaCl. The modified membranes were also found to be stable against mechanical backwashing (up to 80 LMH) and chemical regeneration (in acidic conditions and basic/oxidizing conditions).
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Wang, Luda, Christopher M. Williams, Michael S. H. Boutilier, Piran R. Kidambi, and Rohit Karnik. "Single-Layer Graphene Membranes Withstand Ultrahigh Applied Pressure." Nano Letters 17, no. 5 (April 24, 2017): 3081–88. http://dx.doi.org/10.1021/acs.nanolett.7b00442.
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Rodríguez-Sánchez, Ingrid Juliet, Natalia Fernanda Vergara-Villa, Dianney Clavijo-Grimaldo, Carlos Alberto Fuenmayor, and Carlos Mario Zuluaga-Domínguez. "Ultrathin single and multiple layer electrospun fibrous membranes of polycaprolactone and polysaccharides." Journal of Bioactive and Compatible Polymers 35, no. 4-5 (July 2020): 351–62. http://dx.doi.org/10.1177/0883911520944422.
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Electrospinning was used to produce fibrous membranes, in single and multiple layers, from poly(ε-caprolactone), pullulan, and from mixtures of poly(ε-caprolactone) with potato modified starch and β-glucan. It was possible to obtain single-layer membranes from solutions of pullulan in water, poly(ε-caprolactone) in chloroform, and from mixtures of poly(ε-caprolactone)/β-glucan and poly(ε-caprolactone)/potato modified starch in chloroform. Scanning electron microscopy images showed the formation of ultrathin homogeneous fibers from electrospun poly(ε-caprolactone) and pullulan, whereas the fibers obtained from mixtures of poly(ε-caprolactone)/ β -glucan and poly(ε-caprolactone)/potato modified starch had different sizes and morphologies, as well as irregular microstructures, characterized by the presence of beads. Contact angle analyses showed that pullulan membranes were extremely hydrophilic, while poly(ε-caprolactone) membranes were predominantly hydrophobic. Subsequently, poly(ε-caprolactone)-pullulan-poly(ε-caprolactone) multilayer membranes, with intermediate wettability, were prepared by successive electrospinning steps. Infrared spectroscopy and calorimetric analyses showed the presence of both polymers and the absence of changes in their structure and stability due to electrospinning, indicating adequate compatibility between the two polymers. We foresee that the polyester-polysaccharide multilayer membrane might be used as a biodegradable vehicle for active agents with different hydrophobicity, with applications as food packaging and biocompatible scaffold materials.
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Kawasaki, Masahiro, Hiroyuki Yoshikawa, Masato Saito, Shu Jiang, Takehiro Akeyama, Eiichi Tamiya, and Minoru Noda. "A New Type of LSPR Sensor Featuring Immobilized Liposome or Phospholipid Single Layer." Proceedings 2, no. 13 (December 4, 2018): 791. http://dx.doi.org/10.3390/proceedings2130791.
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We have fabricated a new type of LSPR sensor featuring immobilized liposome or phospholipid single layer. LSPR principally shows an ultrahigh sensitivity on surface dielectric environmental change due to interaction with target, but little has been reported so far on applying phospholipid membranes and/or liposomes as model cell membrane. We newly tried to investigate biosensing capabilities using the membranes of the both structures on Au nanostructures of LSPR sensor chip. As a result, it was confirmed that the phospholipid single layer is more effective to improve the sensitivity than the liposome. Finally, we have clearly detected 100 nM target protein of CAB and estimated a possible detection of 10 nM range from wavelength resolution by interaction with the phospholipid single layer.
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Shawaqfeh, Ahmad T., and Ruth E. Baltus. "Fabrication and characterization of single layer and multi-layer anodic alumina membranes." Journal of Membrane Science 157, no. 2 (May 1999): 147–58. http://dx.doi.org/10.1016/s0376-7388(98)00314-7.
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Drahushuk, Lee W., and Michael S. Strano. "Mechanisms of Gas Permeation through Single Layer Graphene Membranes." Langmuir 28, no. 48 (November 19, 2012): 16671–78. http://dx.doi.org/10.1021/la303468r.
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Yoon, Soong‐Seok, Hyun‐Kyung Lee, and Se‐Ryeong Hong. "CO2/N2 Gas Separation Using Pebax/ZIF-7—PSf Composite Membranes." Membranes 11, no. 9 (September 14, 2021): 708. http://dx.doi.org/10.3390/membranes11090708.
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In this study, we mixed the zeolitic imidazolate framework-7 (ZIF-7) with poly(ether-b-amide)® 2533 (Pebax-2533) and used it as a selective layer for a composite membrane. We prepared the composite membrane’s substrate using polysulfone (PSf), adjusted its pore size using polyethylene glycol (PEG), and applied polydimethylsiloxane (PDMS) to the gutter layer and the coating layer. Then, we investigated the membrane’s properties of gases by penetrating a single gas (N2, CO2) into the membrane. We identified the peaks and geometry of ZIF-7 to determine if it had been successfully synthesized. We confirmed that ZIF-7 had a BET surface area of 303 m2/g, a significantly high Langmuir surface area of 511 m2/g, and a high CO2/N2 adsorption selectivity of approximately 50. Considering the gas permeation, with ZIF-7 mixed into Pebax-2533, N2 permeation decreased from 2.68 GPU in a pure membrane to 0.43 GPU in the membrane with ZIF-7 25 wt%. CO2 permeation increased from 18.43 GPU in the pure membrane to 26.22 GPU in the ZIF-7 35 wt%. The CO2/N2 ideal selectivity increased from 6.88 in the pure membrane to 50.43 in the ZIF-7 25 wt%. Among the membranes, Pebax-2533/ZIF-7 25 wt% showed the highest permeation properties and the characteristics of CO2-friendly ZIF-7.
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Fathizadeh, Mahdi, Weiwei L. Xu, Margaret Shen, Emily Jeng, Fanglei Zhou, Qiaobei Dong, Dinesh Behera, et al. "Antifouling UV-treated GO/PES hollow fiber membranes in a membrane bioreactor (MBR)." Environmental Science: Water Research & Technology 5, no. 7 (2019): 1244–52. http://dx.doi.org/10.1039/c9ew00217k.
Full textDissertations / Theses on the topic "Single layer membranes"
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Peña, Viñamil Diana Maritza. "Aplicación de los principios del tensegrity a las constucciones textiles atirantadas." Doctoral thesis, Universitat Politècnica de Catalunya, 2012. http://hdl.handle.net/10803/96774.
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The purpose of this document is to study the application of Tensegrity principles on tensile textile constructions. This work studies
the basic concept of Tensegrity unit, its classification according a previous researcher (Anthony Pugh) and the author’s
contribution, focused on new generations of forms. Through the geometry and computer software, another typology and a
constructive simple method is developed, bearing in mind, some aspects as important as system pretension to find its balanceEl propósito de esta tesis es el estudio de la aplicación de los principios del tensegrity a las construcciones textiles atirantadas. El estudio del concepto básico de la unidad tensegrity, sus clasificaciones según investigadores anteriores (Anthony Pugh) y el aporte personal de nuevas generaciones de forma por medio de la geometría y programas informáticos, otra tipología y un método constructivo sencillo de realizar teniendo en cuenta aspectos tan importantes como la pretensión del sistema para buscar el equilibrio del mismo. La contribución clave de este prototipo en el campo de las estructuras ligeras es que es la primera vez que un anillo tensegrity ha sido utilizado en lugar de un anillo de compresión, para generar un domo completamente en tensegrity. Además se reemplazaron los tensores de los tensegritis tradicionales por membranas.
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Bilyard, Thomas. "Single molecule studies of F1-ATPase and the application of external torque." Thesis, University of Oxford, 2009. http://ora.ox.ac.uk/objects/uuid:9f369674-4105-4bf1-a0ce-023db1f8bd7f.
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F1-ATPase, the sector of ATP synthase where the synthesis of cellular ATP occurs, is a rotary molecular motor in its own right. Driven by ATP hydrolysis, direct observation of the rotation of the central axis within single molecules of F1 is possible. Operating at close to 100% efficiency, F1 from thermophilic Bacillus has been shown to produce ~40pN˙nm of torque during rotation. This thesis details the groundwork required for the direct measurement of the torque produced by F1 using a rotary angle clamp, an optical trapping system specifically designed for application to rotary molecular motors. Proof-of-concept experiments will be presented thereby demonstrating the ability to directly manipulate single F1 molecules from Escherichia coli and yeast mitochondria (Saccharomyces cerevisiae), along with activation of F1 out of its inhibited state by the application of external torque. Despite in-depth knowledge of the rotary mechanism of F1 from thermophilic Bacillus, the rotation of F1 from Escherichia coli is relatively poorly understood. A detailed mechanical characterization of E.coli F1 will be presented here, with particular attention to the ground states within the catalytic cycle, notably the ATP-binding state, the catalytic state and the inhibited state. The fundamental mechanism of E.coli F1 appears to depart little from that of F1 from thermophilic Bacillus, although, at room temperature, chemical processes occur faster within the E.coli enzyme, in line with considerations regarding the physiological conditions of the different species. Also presented here is the verification of the rotary nature of yeast mitochondrial F1. The torque produced by F1 from thermophilic Bacillus, E.coli and yeast mitochondria is the same, within experimental error, despite their diverse evolutionary and environmental origins.
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Thompson, James Russell. "Imaging the assembly of the Staphylococcal pore-forming toxin alpha-Hemolysin." Thesis, University of Oxford, 2009. http://ora.ox.ac.uk/objects/uuid:e320004a-6118-4dac-af2a-eca6e90be7ac.
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Alpha-hemolysin is a pore-forming toxin secreted by pathogenic Staphylococcus aureus. Its spontaneous oligomerization and assembly into a trans-bilayer beta-barrel pore is a model for the assembly of many other pore-forming toxins. It is studied here in vitro as a means to probe general membrane protein oligomerization and lipid bilayer insertion. This thesis details the results of experiments to develop and implement a novel in vitro lipid bilayer system, Droplet-on-Hydrogel Bilayers (DHBs) for the single-molecule imaging of alpha-hemolysin assembly. Chapter 2 describes the development of DHBs and their electrical characterization. Experiments show the detection of membrane channels in SDS-PAGE gels post-electrophoresis and DHBs use as a platform for nanopore stochastic sensing. Chapter 3 describes the engineering and characterization of fluorescently-labelled monomeric alpha-hemolysin for use in protein assembly imaging experiments described in Chapter 6. Chapter 4 describes the characterization of DHB lipid fluidity and suitability for single-molecule studies of membrane protein diffusion. In addition, a novel single-particle tracking algorithm is described. Chapter 5 describes experiments demonstrating simultaneous electrical and fluorescence measurements of alpha-hemolysin pores embedded within DHBs. The first multiple-pore stochastic sensing in a single-lipid bilayer is also described. Chapter 6 describes experiments studying the assembly of alpha-hemolysin monomers in DHBs. Results show that alpha-hemolysin assembles rapidly into its oligomeric state, with no detection of long-lived intermediate states.
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Seidel, Marco Thomas. "Solvatationsdynamik an biologischen Grenzschichten." Doctoral thesis, [S.l.] : [s.n.], 2003. http://deposit.ddb.de/cgi-bin/dokserv?idn=969974124.
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Boztepe, Inci. "Examination of Hydrophobic/Hydrophilic Dual Layer Membranes for Membrane Distillation." Thesis, 2018. https://vuir.vu.edu.au/40253/.
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Membrane Distillation (MD) is a separation technology that uses a temperature difference across a membrane to purify water. Membrane distillation has been known since the early 1960s and there are still breakthroughs to be made. Improvements in the module design or new membranes materials, such as composite membranes, are being investigated, and much research has focused on these aspects.
This study focused on membrane distillation performance for direct contact membrane distillation with 5 different membranes, which included 3 hydrophobic and 2 hydrophobic/hydrophilic dual layer membranes. Their performance was modelled using mathematical modelling program MATLAB. The purpose of the study was to predict the flux and energy efficiency for membranes, and verify with the experimental work. This work extended membrane distillation 1-D modelling to dual layer membranes, which has not previously been performed. The approach of the study required membrane characterization tests to provide input parameters to the model, and also serve as parameters for explaining the flux performance of the membranes. The membrane characteristics measured were porosity, thickness, tortuosity and pore size. Membrane distillation experiments were performed at different feed and cold inlet temperatures and flowrates, and permeate fluxes for various membranes and different operating conditions were measured and analysed.
The experimental results were compared with predictions from the mathematical modelling for both the single layer and dual layer membranes, and very good agreements have been found. Error was within 10% for flux and energy efficiencies between the experiments and the model. Single layer membranes’ performances were found better than dual layer membranes. The thickness of the hydrophobic layer was the highest among the other membranes, hence it affected heat and mass transfer across the membrane adversely compared to single layer membranes. Therefore, the permeate flux and energy efficiency was lower for dual layer membrane compared to single layer membranes. Better performance for single layer membranes can be attributed to their characteristics.
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"C2C12 wound dynamics after single cell photoporation by femtosecond laser." 2014. http://repository.lib.cuhk.edu.hk/en/item/cuhk-1291553.
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Cell wounding, the loss of plasma membrane integrity, is a common event in the life of many cell types. Most cells are subjected to physiological events during normal functions that can lead to disruption of their plasma membranes, especially cells in the load bearing organs such as muscle, skin and bone. The capacity of the cell to repair day-to-day wear-and-tear injuries, as well as traumatic ones, is fundamental for maintaining tissue integrity.In this thesis, we were trying to uncover single cell wound responses by applying the femtosecond laser (fs laser) technology. A well-characterized tunable fs laser was coupled with a laser scanning confocal microscopic system. Combining real-time observations of the fs laser-induced wound and 3D reconstruction of the cells, post-damage cell and nucleus morphological transformation and wound dynamics were reported. The major findings of this study include: (1) Fs laser could induce a small hole on the plasma membrane of the targeted cell. With the same laser irradiation time, the initial hole size were positively correlated with the laser power. (2) Four typical hole evolution scenarios were reported. Hole resealing was a fast process mostly within 100 seconds in normal condition. Whether a cell could reseal the hole is dependent on the initial hole size. Cells had difficulty to cope with the bigger holes. Three ranges of hole size were given in the thesis to predict the hole resealing result. (3) After fs laser damage, the whole cell underwent a contraction. The post-damage nucleus area, footprint, and each section layer of the cell all shrank, only the thickness remained the same. The nucleus retreated a bit from the damage site after damage. (4) Oxidative stress altered some of the cellular responses to the laser damage. The fs laser- induced holes in oxidative groups were bigger than the normal condition. The cells underwent an overall swelling after fs laser damage instead of the contraction in the normal group. Section layer areas and the thickness of the cell increased after damage. But similar to the normal condition, nucleus shrinkage and retreat from the damage site were also found in the oxidative stress groups. (5) Although both acute and chronic oxidative stresses compromised the integrity of the plasma membrane, chronic oxidative stress compromised more severely with several critical post-damage cell transformations and low resealing ratio. Acute oxidative stress on the other hand may somehow promote the resealing ability of the cells. (6) The section layers closer to the bottom of the cells transformed less than the layers further away from the bottom. This probably suggested that the cell basal attachment provided a constraint force to the plasma membrane for morphological changes.
細胞創傷，即細胞膜的完整性受損，是多種細胞生命週期中一種常見的現象。細胞在執行正常功能時可能遭遇不同程度的生理性損傷，其中大部分會導致細胞膜的破壞。這一現象對存在於承受壓力器官中的細胞更為頻繁，例如肌肉，皮膚和骨骼。細胞對於日常磨損性傷害以及意外創傷的修復能力，是維持組織完整性的基石。
在本論文中，我們通過使用飛秒鐳射技術模擬單細胞創傷，觀察並試圖揭示單細胞對於創傷的反應過程。在實驗中，參數可調的飛秒鐳射器與共軛聚焦顯微鏡整合為一個系統，用於在單細胞膜上進行定點損傷。我們結合了對損傷的即時觀測，細胞的三維結構重建技術，完整記錄了損傷前後的損傷部位，細胞整體以及細胞核的形態變化。以下是本研究的主要發現：（1）飛秒鐳射能夠在目標細胞的細胞膜上進行局部穿孔。在鐳射照射時間相同的情況下，鐳射穿孔的大小與鐳射的平均功率呈正相關。（2）我們發現了鐳射穿孔後穿孔部位有四種不同的變化情況。穿孔後細胞封孔是一相當快的過程，在細胞成功封孔的情況下，大部分細胞將在100秒以內將穿孔部位重新填滿。細胞是否可以將穿孔封住取決於鐳射照射後初始穿孔的大小。細胞很難修復較大的孔。我們將細胞初始穿孔大小分為三個範圍，根據這三個範圍可以利用初始孔的尺寸大致預測穿孔後細胞的封孔情況。（3）飛秒鐳射損傷細胞後，細胞將會收縮，並且細胞核的平面面積，細胞的平面面積（或稱細胞足跡），以及細胞各分層面積都有不同程度的縮小。僅細胞厚度未發生顯著變化。同時，細胞核的位置相對於損傷部位有所後退。（4）細胞在氧化應激過後，對於飛秒鐳射造成的損傷反應有所變化。具體表現為：鐳射穿孔的尺寸比正常情況下更大；穿孔後細胞將會整體腫脹而非收縮。各分層面積和細胞厚度都有不同程度的增大。但是細胞核的反應與正常情況類似，即細胞核將會收縮，並且後退以遠離鐳射損傷部位。（5）儘管急性氧化應激和慢性氧化應激都一定程度上損傷了細胞膜的完整性，但是從細胞對於鐳射創傷的反應觀察，長期慢性氧化應激對於細胞膜的損害更為嚴重，具體表現為鐳射損傷後細胞的嚴重形變和細胞膜修復比例的降低。而另一方面，急性氧化應激在某種程度上可以增強細胞對於鐳射穿孔的修復能力。（6）細胞膜穿孔後，細胞各層的面積變化不一，位置越靠近底層的分層面積變化越小。這可能表明細胞貼壁行為形成了一個對細胞形變的約束力。
Duan, Xinxing.
Thesis M.Phil. Chinese University of Hong Kong 2014.
Includes bibliographical references (leaves 73-85).
Abstracts also in Chinese.
Title from PDF title page (viewed on 24, October, 2016).
Detailed summary in vernacular field only.
Detailed summary in vernacular field only.
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Wu, Chung-Ching, and 吳忠慶. "Preparation of Pulsed Electrodeposited Platinum Catalyst Layer on Novel Single-Layer Gas Diffusion Electrode for Proton Exchange Membrane Fuel Cell." Thesis, 2011. http://ndltd.ncl.edu.tw/handle/t359ym.
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碩士中原大學
奈米科技碩士學位學程
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A novel Platinum catalyst (PC) deposited single layer gas duffusion electrode (SL-GDEs), which is different from the multi-layer structure of traditional electrode, was successfully prepared by the electrodeposition (ED) method. The morphology, particle size, crystallization and electrocatalytic activity of the PC layer prepared with different deposition parameters were characterized by SEM, XRD and cyclic voltammetry, respectively. The performances of the membrane electrode assemblys (MEAs) fabricated by the SL-GDEs with various amount of PC and Nafion® NRE-212 were measured by a home-made single cell test instrument。 The results showed that the better electrocatalytic activities, crystallization and electrochemical active surface area (EAS) of PC layers were obtained by the pulse electrodeposition method. The pulse current density of 200 mAcm-2, Ton/Toff = 0.001/0.005s and Charge density of 1Ccm-2 was the optimum parameter (200PA1-2). The MEA, M200PA1-2, was fabricated by the electrode of 200PA1-2 deposited SL-GDEs with Pt loading of 0.04 mgcm-2 and Nafion® NRE-212. The single cell test of M200PA1-2 with H2/O2 gases showed that the best currents and power densities at 0.4 V were 200 mAcm-2 and 79 mWcm-2, respectively. The Platinum mass specific power was 988 Wg-1, which was 136% and 168% higher than the values obtained from the PC of catalysts coated SL-GDEs and commercial carbon paper (GDE-600), respectively.
Books on the topic "Single layer membranes"
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Vincent, Angela. Neuroimmunology. Oxford University Press, 2015. http://dx.doi.org/10.1093/med/9780199658602.003.0015.
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This chapter relates to antibody-mediated disorders throughout the nervous system. Early papers recall how use of bungarotoxin, passive transfer experiments in mice, and clinical response to plasma exchange confirmed the role of acetylcholine receptor antibodies in myasthenia gravis. Cutting edge techniques subsequently discovered other key neuromuscular junctional proteins, including muscle-specific kinase an additional target for antibodies. Later papers report the link between brain inflammation and severe amnesia, paraneoplastic and non-paraneoplastic, and the identification of the first pathogenic antibodies to a central nervous system (CNS) receptor in Rasmussen’s syndrome. The first report of “Morvan’s syndrome” is followed by a single patient with antibodies immunoprecipitating potassium channels who improved remarkably with plasma exchange. Lastly, the patients in the 1920’s encephalitis lethargica epidemic described in detail by von Economo, exhibited many of the features now recognised as caused by antibodies to various CNS receptors and associated membrane proteins.
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Raghunathan, Karthik, and Andrew Shaw. Crystalloids in critical illness. Oxford University Press, 2016. http://dx.doi.org/10.1093/med/9780199600830.003.0057.
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‘Crystalloid’ refers to solutions of crystalline substances that can pass through a semipermeable membrane and are distributed widely in body fluid compartments. The conventional Starling model predicts transvascular exchange based on the net balance of opposing hydrostatic and oncotic forces. Based on this model, colloids might be considered superior resuscitative fluids. However, observations of fluid behaviour during critical illness are not consistent with such predictions. Large randomized controlled studies have consistently found that colloids offer no survival advantage relative to crystalloids in critically-ill patients. A revised Starling model describes a central role for the endothelial glycocalyx in determining fluid disposition. This model supports crystalloid utilization in most critical care settings where the endothelial surface layer is disrupted and lower capillary pressures (hypovolaemia) make volume expansion with crystalloids effective, since transvascular filtration decreases, intravascular retention increases and clearance is significantly reduced. There are important negative consequences of both inadequate and excessive crystalloid resuscitation. Precise dosing may be titrated based on functional measures of preload responsiveness like pulse pressure variation or responses to manoeuvres such as passive leg raising. Crystalloids have variable electrolyte concentrations, volumes of distribution, and, consequently variable effects on plasma pH. Choosing balanced crystalloid solutions for resuscitation may be potentially advantageous versus ‘normal’ (isotonic, 0.9%) saline solutions. When used as the primary fluid for resuscitation, saline solutions may have adverse effects in critically-ill patients secondary to a reduction in the strong ion difference and hyperchloraemic, metabolic acidosis. Significant negative effects on immune and renal function may result as well.
Book chapters on the topic "Single layer membranes"
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Glaser, Roland, and Günter Fuhr. "Electrorotation of Single Cells — A New Method for Assessment of Membrane Properties." In Electrical Double Layers in Biology, 227–42. Boston, MA: Springer US, 1986. http://dx.doi.org/10.1007/978-1-4684-8145-7_16.
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Channon, Keith, and Patrick Vallance. "Blood vessels and the endothelium." In Oxford Textbook of Medicine, edited by Jeremy Dwight, 3241–53. Oxford University Press, 2020. http://dx.doi.org/10.1093/med/9780198746690.003.0338.
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The blood vessel wall consists of three layers: the intima, media, and adventitia. Not all vessels have each layer, and the layers vary in size and structure between vessels. The intima is made up of a single layer of endothelial cells on a basement membrane, beneath which—depending on vessel size—there may be a layer of fibroelastic connective tissue and an internal elastic lamina that provides both structure and flexibility. Embedded in the intima are pericytes. The media is made up of smooth muscle cells, elastic laminae, and extracellular matrix. The adventitia is the outermost part of the vessel, composed mainly of fibroelastic tissue but also containing nerves, small feeding blood vessels (the vasa vasorum), and lymph vessels. The adventitia is directly related to the surrounding perivascular adipose tissue.
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Vallance, Patrick, and Keith Channon. "Blood vessels and the endothelium." In Oxford Textbook of Medicine, 2593–603. Oxford University Press, 2010. http://dx.doi.org/10.1093/med/9780199204854.003.160101_update_002.
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The blood vessel wall consists of the intima, the media, and the adventitia. Not all vessels have each layer, and the layers vary in size and structure between vessels. (1) The intima is made up of a single layer of endothelial cells on a basement membrane, beneath which—depending on vessel size—there may be a layer of fibroelastic connective tissue and an internal elastic lamina that provides both structure and flexibility. Embedded in the intima are pericytes. (2) The media is made up of smooth muscle cells, elastic laminae and extracellular matrix. (3) The adventitia is the outermost part of the vessel, composed mainly of fibroelastic tissue but also containing nerves, small feeding blood vessels (the vasa vasorum), and lymph vessels. The adventitia is directly related to the surrounding perivascular adipose tissue....
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Khemakhem, Sabeur. "Preparation and Evaluation of Hydrophobic Grafted Ceramic Membrane: For Application in Water Desalination." In Wastewater Treatment. IntechOpen, 2022. http://dx.doi.org/10.5772/intechopen.104899.
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A new inorganic hydrophobic porous membrane was prepared and applied in desalination with the air-gap membrane distillation process. Ceramic supports from low-cost natural Tunisian sand have been elaborated by the extrusion method. The microfiltration layer has been elaborated from ZrO2 powder by slip casting technical using a solution of water, sand powder, and polyvinyl alcohol solution. The hydrophobic surface of the active layer was elaborated by grafting 1H,1H,2H,2H-perfluorodecyltriethoxysilane on the ceramic microfiltration membrane surface (Tunisian Sand/Zirconia), to prepare a hydrophobic surface. The contact angle method allows showing the hydrophobic nature on the grafted membrane surface since it increases from 25° before grafting to values exceeding 140° after grafting. The efficiency of the grafting process was characterized by scanning electron microscopy (SEM). The membrane permeability varies from 700 l.h−1.m−2 before grafting to 10 l.h−1.m−2 after grafting. The new hydrophobic membrane seems to be promising in the field of membrane distillation. Salt retention higher than 98% was obtained using a modified microfiltration ceramic membrane.
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Ghasem, Nayef Mohamed, Nihmiya Abdul Rahim, and Mohamed Al-Marzouqi. "Carbon Capture From Natural Gas via Polymeric Membranes." In Advances in Environmental Engineering and Green Technologies, 117–31. IGI Global, 2019. http://dx.doi.org/10.4018/978-1-5225-7359-3.ch009.
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Polymeric membrane is a promising energy and an active alternative for conventional CO2 absorption column. The type of absorption liquid and operating parameters plays an efficient role in the ultimate absorption/stripping performance using gas-liquid membrane contactor. The gas flow rate has a significant effect on CO2 absorption performance; by contrast, it has no effect on stripping performance. Further, the CO2 absorption performance in membrane contactor could be enhanced by high liquid flow rates. The gas-liquid contact time was a key factor in enhancing the stripping flux at low temperature while liquid phase boundary layer thickness and associated mass transfer resistance is important at elevated temperature. By controlling the liquid phase velocity and the length of module at low temperature, better stripping performance can be achieved. The effect of liquid temperature on absorption performance in gas-liquid is not straightforward, since the liquid temperature cooperatively influences several factors.
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Ghasem, Nayef Mohamed, Nihmiya Abdul Rahim, and Mohamed Al-Marzouqi. "Carbon Capture From Natural Gas via Polymeric Membranes." In Encyclopedia of Information Science and Technology, Fourth Edition, 3043–55. IGI Global, 2018. http://dx.doi.org/10.4018/978-1-5225-2255-3.ch266.
Full textAbstract:
Polymeric membrane is a promising energy effective and an active alternative for conventional CO2 absorption column. The type of absorption liquid and operating parameters plays an efficient role in the ultimate absorption/stripping performance using gas-liquid membrane contactor. The gas flow rate has a significant effect on CO2 absorption performance, by contrast, it has no effect on stripping performance. Further the CO2 absorption performance in membrane contactor could be enhanced by high liquid flow rates. Because the gas–liquid contact time was a key factor to enhance the stripping flux at low temperature while liquid phase boundary layer thickness and associated mass transfer resistance is important at elevated temperature. So by controlling the liquid phase velocity and the length of module at low temperature better stripping performance can be achieved. The effect of liquid temperature on absorption performance in gas-liquid is not straightforward, since the liquid temperature cooperatively influence several factors.
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Davis, Carl. "ECMO for Congenital Diaphragmatic Hernia." In Extracorporeal Membrane Oxygenation, edited by Marc O. Maybauer, 233–46. Oxford University Press, 2022. http://dx.doi.org/10.1093/med/9780197521304.003.0022.
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The management of congenital diaphragmatic hernia (CDH) is challenging and complex, not because of the defect per se, which is technically relatively straightforward to correct, but because of the varying impact of pre- and postnatal influences on the underlying cardiorespiratory physiology. The defect is now detected antenatally in over 75% of cases. Efforts to accurately identify high-risk babies have only been partially successful but have been useful in prenatal counseling. Delivery and postnatal management, especially of high-risk neonates with CDH, in specialized units has improved survival, especially since the use of lung-protective strategies was introduced in the 1980s and the later recognition of impaired cardiac function and the impact of pulmonary hypertension on cardiac function. This has led to a more rational approach to conventional management. Despite these improvements in management, a significant number of babies will fail to improve with conventional management, and ECMO will need to be considered. This chapter explores the use of ECMO in managing these babies as well as its limitations and complications. A case discussion followed by a critical review of the literature, as well as critical care board-type multiple-choice questions, summarize this chapter as a concise learning and study tool for the role of ECMO in CDH.
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Maynard Smith, John, and Eors Szathmary. "The origin of eukaryotes." In The Major Transitions in Evolution. Oxford University Press, 1997. http://dx.doi.org/10.1093/oso/9780198502944.003.0012.
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The basic structures of a bacterial and a eukaryotic cell are shown in Fig. 8.1. The differences whose origins call for an explanation are as follows: • The bacterial cell has a rigid outer cell wall, usually made of the peptidoglycan, murein. In eukaryotes, the rigid cell wall is not universal, and cell shape is maintained primarily by an internal cytoskeleton of filaments and microtubules. • Eukaryotic cells have a complex system of internal membranes, including the nuclear envelope, endoplasmic reticulum and lysosomes. • Bacteria have a single circular chromosome, attached to the rigid outer cell wall. In eukaryotes, linear chromosomes are contained within a nuclear envelope, which separates transcription from translation: communication between nucleus and cytoplasm is via pores in the nuclear envelope. • Eukaryotes have a complex cytoskeleton. The actomyosin system powers cell division, phagocytosis, amoeboid motion and the overall contractility to resist osmotic swelling. Microtubules and the associated motor proteins (kinesin, dynein and dynamin) ensure the accurate segregation of chromosomes in mitosis, ciliary motility and the movement of transport vesicles. Intermediate filaments form the structural basis for the association of the endomembranes and nuclear-pore complexes with the chromatin to form the nuclear envelope, while other intermediate filaments help to anchor the nucleus in the cytoplasm. One crucial difference between prokaryotes and most eukaryotes has been omitted from Fig. 8.1: this is the presence of mitochondria, and, in plants and algae, of chloroplasts. The reason for the omission is that, on the scenario for eukaryote origins that seems to us most plausible, these intracellular organelles originated later in time than the structures shown in the figure. The differences between these cell types justifies the recognition of two empires of life (above the kingdom level): Bacteria and Eukaryota (Cavalier-Smith, 199la; Table 8.1). (It is interesting that this taxonomic rank was recognized by Linnaeus.) Within each of the empires, there are two major categories: Bacteria consist of the kingdoms Eubacteria and Archaebacteria, and Eukaryota are divided into the superkingdoms Archaezoa and Metakaryota. The justification for these divisions is as follows. The Archaebacteria, in contrast to the Eubacteria, never have murein cell walls, and their single cell membrane contains isoprenoidal ether rather than acyl ester lipids.
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Emmett, Stevan R., Nicola Hill, and Federico Dajas-Bailador. "Infectious disease." In Clinical Pharmacology for Prescribing. Oxford University Press, 2019. http://dx.doi.org/10.1093/oso/9780199694938.003.0019.
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Antibiotics include an extensive range of agents able to kill or prevent reproduction of bacteria in the body, without being overly toxic to the patient. Traditionally derived from living organisms, most are now chemically synthesized and act to disrupt the integrity of the bacterial cell wall, or penetrate the cell and disrupt protein synthesis or nucleic acid replication. Typically, bacteria are identified according to their appearance under the microscope depending on shape and response to the Gram stain test. Further identification is obtained by growth characteristics on various types of culture media, based on broth or agar, biochemical and immunological profiles. Further testing on broth or agar determines antibiotic sensitivity to guide on antibiotic therapy in individual patients. This process can take 24– 48 hours to culture and a further 24– 48 hours to measure sensitivities. Increasingly, new technology, e.g. Matrix Assisted Laser Desorption Ionization— Time of Flight (MALDI- TOF) and nucleic acid amplification assays, are being used to provide more rapid identification. The Gram classification, however, is still widely referred to as it differentiates bacteria by the presence or absence of the outer lipid membrane (see Figure 11.1), a fundamental characteristic that influences antibiotic management. Antimicrobial agents rely on selective action exploiting genetic differences between bacterial and eukaryotic cells. They target bacterial cell wall synthesis, bacterial protein synthesis, microbial DNA or RNA synthesis, by acting on bacterial cell metabolic pathways or by inhibiting the action of a bacterial toxin (see Table 11.1). Both Gram- positive and Gram- negative bacteria possess a rigid cell wall able to protect the bacteria from varying osmotic pressures (Figure 11.1). Peptidoglycan gives the cell wall its rigidity and is composed of a glycan chain of complex alternating carbohydrates, N- acetylglucosamide (N- ATG), and N- acetylmurcarinic acid (N- ATM), that are cross- linked by peptide (or glycine) chains. In Gram-positive bacteria, the cell wall contains multiple peptidoglycan layers, interspersed with teichoic acids, whereas Gram- negative bacteria contain only one or two peptidoglycan layers that are surrounded by an outer membrane attached by lipoproteins. The outer membrane contains porins (which regulate transport of substances into and out of the cell), lipopolysaccharides, and outer proteins in a phospholipid bilayer. For both Gram- negative and Gram-positive bacteria, peptidoglycan synthesis involves about 30 bacterial enzymes acting over three stages. Since the cell wall is unique to bacteria, it makes a suitable target for antibiotic therapy.
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S. Sidhu, Mehra, and Nitish Dhingra. "Ablation of Materials Using Femtosecond Lasers and Electron Beams." In Fundamentals and Application of Femtosecond Optics [Working Title]. IntechOpen, 2022. http://dx.doi.org/10.5772/intechopen.106198.
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The advancements in producing interactions of concentrated energy fluxes, such as femtosecond lasers and high-energy electron beams with the absorbing substances, have facilitated new discoveries and excitement in various scientific and technological areas. Since their invention, significant improvements in temporal, spatial, energetic, and spectroscopic characteristics have been realized. Due to the ultrashort pulse width and higher intensity (1012 W/cm2), it is possible to ablate the materials with negligible damage outside the focal volume, thereby allowing the treatment of biological samples, such as live cells, membranes, and removal of thin films, as well as bulk materials for many applications in diverse fields, including micro-optics, electronics, and even biology under extremely high precision. Since most biological systems are transparent toward the NIR spectral range, it follows the nonlinear multi-photon absorption interaction mechanism. In contrast, the electron beam follows linear absorption mechanism for material modifications even at lower energies. For realizing the fs-laser nano-processing in material applications, such as silicon microchips, or in biology like retinal cells, it is crucial to find a way to deliver these pulses precisely at the site of action and enhance the selectivity. The utilization of electron beams in material modification has also been exercised widely to attain nanoscale precision. In the next section, biological materials, such as cornea, retina, and silk, are discussed.
Conference papers on the topic "Single layer membranes"
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Reissman, Timothy, Austin Fang, Ephrahim Garcia, Brian J. Kirby, Romain Viard, and Philippe M. Fauchet. "Inorganic Proton Exchange Membranes." In ASME 2006 4th International Conference on Fuel Cell Science, Engineering and Technology. ASMEDC, 2006. http://dx.doi.org/10.1115/fuelcell2006-97149.
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Direct Methanol Fuel Cells (DMFCs) offer advantages from quick refills to the elimination of recharge times. They show the most potential in efficient chemical to electrical energy conversion, but currently one major source of inefficiency within the DMFC system is the electrolyte allowing fuel to cross over from the anode to cathode. Proprietary DuPont™ Nafion® 117 has been the standard polymer electrolyte thus far for all meso-scale direct methanol power conversion systems, and its shortcomings consist primarily of slow anodic reaction rates and fuel crossover resulting in lower voltage generation or mixed potential. Porous Silicon (P-Si) is traditionally used in photovoltaic and photoluminescence applications but rarely used as a mechanical filter or membrane. This research deals with investigations into using P-Si as a functioning electrolyte to transfer ions from the anode to cathode of a DMFC and the consequences of stacking multiple layers of anodes. Porous silicon was fabricated in a standard Teflon cylindrical cell by an anodization process which varied the current density to etch and electro-polish the silicon membrane. The result was a porous silicon membrane with approximately 1.5 μm pore sizes when optically characterized by a scanning electron microscope. The porous membranes were then coated in approximately 0.2 mg/cm2 Pt-Ru catalyst with a 10% Nafion® solution binding agent onto the anode. Voltage versus current data shows an open circuit voltage (OCV) of 0.25V was achieved with one layer when operating at 20°C. When adding a second porous silicon layer, the OCV was raised to approximately 0.32V under the same conditions. The experimental data suggested that the current collected also increased with an additional identical layer of anode prepared the same way. The single difference was that the air cathode side was surface treated with 0.1 mg of Pt black catalyst combined with a 10% Nafion® binding agent to aid in the recombination of hydrogen atoms to form the water byproduct. Porous silicon endurance runs with 2ml of 3% by volume methanol (0.7425M) fuel dissolved in water showed an operating voltage was generated for approximately 3 hours before the level dropped to approximately 65% of the 0.25V maximum voltage. Endurance runs with a second layer added extended the useful cell life to approximately 5 hours under the same conditions. In an effort to quantify these layering results, Fourier Transform Infrared Spectrometry was conducted on a number of samples to verify decreased methanol concentration present in the second layer.
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Banneyake, B. M. R. U., and Debjyoti Banerjee. "Microfluidic Device for Synthesis of Lipid Bi-Layers." In ASME 2008 Fluids Engineering Division Summer Meeting collocated with the Heat Transfer, Energy Sustainability, and 3rd Energy Nanotechnology Conferences. ASMEDC, 2008. http://dx.doi.org/10.1115/fedsm2008-55219.
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Lipid bi-layers are ubiquitous components of biological cells — and are found in variety of cell components ranging from cell membranes to membranes of organelles inside the cells. In biological membranes, lipid bi-layer membranes carry membrane proteins, which serve as single channel nanopores that are used to study transport of proteins and characterize the properties of proteins. However, lipid bi-layers have very short half lives, which are usually less than an hour. The lipid bi-layers are usually obtained by physico-chemical interactions between a lipid containing organic solvent, an aqueous buffer solution and a hydrophobic surface. We have developed a continuous flow through microfluidic device using pressure driven flow (by means of a tandem syringe pump system) for synthesis of lipid bi-layers. The microfluidic device consists of two glass substrates with micro-channels and microchambers microfabricated using photolithography and wet glass etching. The microchannels in each substrate is in the form of “+” shape and form a mirror image of each other. A Teflon sheet (∼200 microns thickness) is sandwiched between the glass substrates with a ∼200 microns diameter hole etched in the center to communicate with the two sets of microchannels. A lipid solution in an organic solvent (Pentane) and KCl buffer solution are alternately flown through the legs of the microchannel. The conductivity of the buffer is monitored using a current amplifier. The formation of the lipid bi-layer is confirmed by monitoring the resistivity and the impedance to high frequency electrical oscillations. The flow rate in the microfluidic device is optimized to obtain the lipid bi-layer.
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Oviroh, Peter Ozaveshe, Sunday Temitope Oyinbo, Sina Karimzadeh, and Tien-Chien Jen. "Multilayer Separation Effects on MoS2 Membranes in Water Desalination." In ASME 2021 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 2021. http://dx.doi.org/10.1115/imece2021-69156.
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Abstract Climate change and its related effects are imposing severe stress on the current freshwater supplies. This has been exacerbated due to the growth in population, rapid industrialization, and increased energy demand. Increased water requirement is a global challenge. Although more than 70% of the Earth is covered by water, much of it is unusable for human use. Freshwater reservoirs, ponds, and subterranean aquifers account for just 2.5% of the world’s overall freshwater availability. Unfortunately, these water supplies are not very unevenly spread. Therefore, the need to augment these supplies through the desalination of seawater or brackish water. Reverse osmosis (RO) is currently the most widespread method of desalination. However, the unit cost of water is still high partly due to the thin-film composite (TFC) polymer membranes used in the current desalination system. Thus the need for low-cost nanomaterials for Water Desalination and Purification. A promising way to meet this demand is to use two-dimensional (2D) nanoporous materials such as graphene and MoS2 to minimize energy consumption during the desalination process. New nanotechnology methodologies that apply reverse osmosis have been developed. Among some of these technologies is using 2D materials such as graphene and MoS2, which have been studied extensively for water desalination. Single-layer nanoporous 2D materials such as graphene and MoS2 promises better filtrations in the water channel. Although single-layer MoS2 (SL_MoS2) membrane have much promise in the RO desalination membrane, multilayer MoS2 are simpler to make and more cost-efficient. Building on the SL_MoS2 membrane knowledge, we have used the molecular dynamics method (MD) to explore the effects of multilayer MoS2 in water desalination. This comparison is made as a function of the pore size, water flow rate and salt rejection. In addition, we also looked at the effect of the increased interlayer spacing between layers of the nanoporous 2D membrane and then made the comparison. The ions rejection follows the trend trilayer> bilayer> monolayer from results obtained, averaging over all three membrane types studied for the MoS2, the ions rejection follows the trend trilayer > bilayer > monolayer. We find that the thin, narrow layer separation plays a vital role in the successful rejection of salt ions in bilayers and trilayers membranes. These findings will help build and proliferate tunable nanodevices for filtration and other applications.
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Li, Yuhui, and Hao Wang. "Intracellular Ice Formation (IIF) and Plasma Membrane Integrity During Freeze-Thaw Repetitions in a Micro-Thickness Medium Layer." In ASME 2012 Third International Conference on Micro/Nanoscale Heat and Mass Transfer. American Society of Mechanical Engineers, 2012. http://dx.doi.org/10.1115/mnhmt2012-75150.
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Intracellular ice formation (IIF) plays a critical role in cryobiology, though the underlying biophysical mechanisms are still not completely explicable. In this work, a directional freezing scheme integrated with microlayer cell culture was employed to allow directional freezing as well as high-power microscopic observation of IIF in a single optical plane. The initiation of IIF and its spreading within the cells were well observed. The fluorescent reagents were employed to label the cell membrane and nucleus. It was found that the cell membrane could keep intact even though the cell had undergone IIF, and the intact cells could have IIF again in the next freezing cycle until their membranes were finally disrupted. The results shed light on the relationship between IIF and the integrity of cell membrane.
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Mohammadi, Mahshid, and Kendra V. Sharp. "Cost Optimization of a Multilayer Microchannel Dialyzer." In ASME 2013 Summer Bioengineering Conference. American Society of Mechanical Engineers, 2013. http://dx.doi.org/10.1115/sbc2013-14046.
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A microchannel-based hemodialyzer offers a novel approach to hemodialysis practice and holds many promises to improve kidney patients’ life quality and dialysis treatment efficiency. The hallow fiber hemodialyzer, a conventional dialysis device, has certain limitations including non-uniformity of the dialysate flow path which necessitates the use of a high dialysate flow rate. The microchannel-based hemodialyzer with flat membranes remarkably improves the mass transfer characteristics and enables the design of a smaller and less expensive unit with lower dialysate-to-blood flow rate ratios [1, 2]. In the microchannel-based design, successive stacked layers alternate between blood flow and dialysate flow. A porous membrane between these layers allows for the transport of toxins from blood side to dialysis fluid side. A schematic view of a single layer is shown in Fig. 1.
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Yu, Jingrong, Ping Cheng, Zhiqi Ma, and Baolian Yi. "Fabrication of Miniature Silicon Wafer Fuel Cells Using Micro Fabrication Technologies." In ASME 2003 1st International Conference on Fuel Cell Science, Engineering and Technology. ASMEDC, 2003. http://dx.doi.org/10.1115/fuelcell2003-1732.
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The fabrication of miniature silicon wafer fuel cells by micro-fabrication technologies and their performance evaluation are presented in this paper. Various thickness of Nafion membranes, such as Nafion 117, 115, and 112, were tested as electrolytes in a miniature single cell operating with dry H2/O2. Among these membranes, Nafion 112 (with the thinnest thickness) gave the best performance of 92.2 mW/cm2 at 250mA/cm2. In order to enhance the output voltage of the fuel cell, a miniature twin-fuel-cell was fabricated in series using two membrane-electrode-assemblies of Nafion 112 membrane sandwiched between two silicon substrates. The novel structure of the miniature twin-fuel-cell is that the electricity interconnect from the cathode of one cell to the anode of another cell is made on the same plane. The interconnect is fabricated by sputtering a layer of gold on the top of the silicon wafer. Silicon dioxide is deposited on the silicon wafer adjacent to the gold layer to prevent short-circuiting between the twin-cells. At ambient conditions, the measured peak power densities of the miniature twin-fuel-cell operating with H2/O2 and 1.5M methanol/O2, are 190.4mW/cm2 and 15.4mW/cm2, respectively.
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Share, Dylan, Lakshmi Krishnan, Dan Walczyk, David Lesperence, and Raymond Puffer. "Thermal Sealing of Membrane Electrode Assemblies for High-Temperature PEM Fuel Cells." In ASME 2010 8th International Conference on Fuel Cell Science, Engineering and Technology. ASMEDC, 2010. http://dx.doi.org/10.1115/fuelcell2010-33227.
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The main challenges of low temperature (80–120°C) Nafion-based PEM technology are (1) low cathode performance due to slow kinetics of the oxygen reduction reaction (2) high material costs (3) considerable system design and operation for water management (4) low tolerance to impurities in fuel stream and (5) low quality heat resulting in low overall system efficiency. Furthermore, Nafion membranes achieve maximum conductivity only when hydrated, limiting their operation to <100 C. Operating the fuel cell >100 C is desirable to overcome the aforementioned limitations. Though several high temperature membranes for PEMFC have been developed, polybenzimidazole (PBI) membranes with high Phosphoric acid content (>90%) developed by BASF Fuel cell are currently seeing commercial interest. The most vital step in MEA manufacturing is the sealing of the membrane in between the electrode-substrate assembly to form a five-layer architecture. Currently, MEA sealing is done by a thermal seal process. This paper examines the effect of thermal sealing process parameters, namely (1) sealing temperature (2) percent compression (3) sealing time and (4) manufacturer-specified post-processing after sealing on the fuel cell performance. A design of experiments was developed with these input process parameters and the polarization behavior during single cell operation, as well as internal cell resistance, were analyzed as performance parameters. ANOVA analysis revealed the statistically significant input factors for the thermal sealing process, which are essential for the rapid and high-quality manufacturing of membrane electrode assemblies for high temperature fuel cells. Furthermore, a multiphysics model has been developed to allow for further refinement of the MEA sealing process.
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Burheim, Odne S., Signe Kjelstrup, Jon G. Pharoah, Preben J. S. Vie, and Steffen Mo̸ller-Holst. "On the Measured PEMFC Anode and Cathode Reversible Heats." In ASME 2010 8th International Conference on Fuel Cell Science, Engineering and Technology. ASMEDC, 2010. http://dx.doi.org/10.1115/fuelcell2010-33035.
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A recently constructed 2D calorimeter was used to measure the work and the total heat production of a single PEM fuel cell that is operated on hydrogen and oxygen at 50 °C and 1 bar. The cells had different membranes and catalyst layers, but the same porous transport layer and micro-porous layer. In this paper the distribution of the reaction entropy between the anode and the cathode, also known as the Peltier heats, was determined. This was done by the use of the measured heat through the anode and the cathode polarisation plates, the measured cell resistance, the measured overpotential and a fuel cell thermal model. The results show that the reaction entropy is almost solely related to the cathode and that the Peltier heat of the anode is near zero.
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Kalontarov, Michael, Erica E. Jung, Aadhar Jain, Syed Saad Ahsan, and David Erickson. "Hollow Fiber Membrane (HFM) Facilitated CO2 Delivery to a Cyanobacteria Layer for Biofuel Production." In ASME 2013 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 2013. http://dx.doi.org/10.1115/imece2013-66317.
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Photosynthetic bacteria have been shown to be advantageous organisms for biofuel production due to high CO2 fixation efficiencies, fast growth rates, and lower water requirements. Recently, cyanobacteria been metabolically engineered to efficiently secrete their products into a surrounding solution. This has the advantage of potentially eliminating the requirement to harvest and post-process the organisms in order to extract a biofuel, which is one of the most energy and water expensive processes in most biodiesel production strategies. Lagging behind the development of these organisms however has been the development of new photobioreactor (PBR) strategies that can efficiently delivery light and inorganic carbon to the bacteria while extracting the secreted product and O2 from the solution phase. Hollow fiber membranes (HFMs) are a method for bubble-less gas exchange that has been shown to be effective at enhancing mass transfer in applications such as wastewater and landfill treatment. HFM technology could be used to overcome the mass transport challenges associated with photobioreactors. HFM modules have been used to increase mass transfer of CO2 to the bulk media in bench scale PBRs; however, the use of HFM fibers as both a mean to exchange and deliver a gas phase throughout a PBR has not been explored. We have characterized the passive transport along a single fiber in a miniature reactor in previous work. Here we extend our work to arrays of HFM fibers. We performed a range of experiments to characterize bacteria growth rate and distribution as a function fiber spacing and active transport through the fibers, and report optimized values for these variables.
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Gareis, Michael, and Jürgen Maas. "Acoustical Behaviour of Buckling Dielectric Elastomer Actuators." In ASME 2019 Conference on Smart Materials, Adaptive Structures and Intelligent Systems. American Society of Mechanical Engineers, 2019. http://dx.doi.org/10.1115/smasis2019-5747.
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Abstract Dielectric elastomers (DE) are regarded as a potential alternative to conventional actuator technologies. They feature low weight, high strains and low material costs. Their scope of application ranges from sensors, energy generators, smart textiles to biomimetic robots and much more. A few concepts of loudspeakers using DE have been demonstrated by the research community. One of the disadvantages of previously concepts was the need for mechanical bias (e.g. by air pressure). This work proposes a new concept of loudspeaker, which does not need prestretch or other means of mechanical bias. Buckling dielectric elastomer transducers (BDET) use the area expansion of actuated DE to buckle up. This mechanism is used to construct a millimeter-scale loudspeaker with good frequency response in the upper frequency range. The concept is implemented using automatically fabricated multi-layer membranes. The multilayer structure allows to generate more force and has higher flexural rigidity than a single-layer setup. Samples with different amount of layers are fabricated and an analytical model is derived. Measurements of the static deflection, the frequency response and the total harmonic distortion validate the model. The small scale of the speaker allows it to be installed in large arrays and thus might offer a hardware platform for high-resolution beam forming or wave field synthesis.