WorldWideScience

Sample records for fiber membrane module

  1. Economic comparison of transverse and longitudinal flow hollow fiber membrane modules for reverse osmosis and ultrafiltration

    NARCIS (Netherlands)

    Futselaar, H.; Zoontjes, R.J.C.; Reith, T.; Racz, I.G.

    1993-01-01

    The presently used hollow fiber membrane modules consist of a bundle of fibers in a cylindrical polymer or metal shell parallel to the shell axis. The feed solution flows either through the lumen or at the outside parallel to the fibers. This paper compares the performance of these modules with a ne

  2. Monitoring of polymeric membrane fouling in hollow fiber module using ultrasonic nondestructive testing

    Institute of Scientific and Technical Information of China (English)

    LIU Jing-xia; LI Jian-xin; CHEN Xue-mei; ZHANG Yu-zhong

    2006-01-01

    This study describes the development of novel protocols extending the real-time ultrasonic reflectometry(UTDR) for the detection of membrane fouling in hollow fiber module during ultrafiltration(UF) of oily water treatment. A specially designed acoustic sensor with a frequency of 2.5 MHz was used. The hollow fiber membranes used were polysulphone(PSf) UF membranes with MWCO 40 kDa. The wastewaters with three different oily concentrations of 100,500 and 1 000 mg/L were investigated. Diesel oil was utilized as the primary foulant. The results show that the permeate flux declines with operation time and its value becomes lower with the increase of the oily concentration in wastewater. It is found that ultrasonic measurement can detect the fouling and cleaning processes. A new signal analysis protocol-ultrasonic reflected energy was developed. Ultrasonic reflected energy obtained indicates the deposition of oily layer as a function of operation time and its removal after cleaning. The overall flux decline is reasonably correlated with the changes in ultrasonic reflected energy. This research provides the evidence that the ultrasonic reflectometry technique is capable of monitoring membrane fouling and cleaning in hollow fiber modules.

  3. Fiber Attachment Module Experiment (FAME): Using a Multiplexed Miniature Hollow Fiber Membrane Bioreactor Solution for Rapid Process Testing

    Science.gov (United States)

    Lunn, Griffin; Wheeler, Raymond; Hummerick, Mary; Birmele, Michele; Richards, Jeffrey; Coutts, Janelle; Koss, Lawrence; Spencer, Lashelle.; Johnsey, Marissa; Ellis, Ronald

    Bioreactor research, even today, is mostly limited to continuous stirred-tank reactors (CSTRs). These are not an option for microgravity applications due to the lack of a gravity gradient to drive aeration as described by the Archimedes principle. This has led to testing of Hollow Fiber Membrane Bioreactors (HFMBs) for microgravity applications, including possible use for wastewater treatment systems for the International Space Station (ISS). Bioreactors and filtration systems for treating wastewater could avoid the need for harsh pretreatment chemicals and improve overall water recovery. However, the construction of these reactors is difficult and commercial off-the-shelf (COTS) versions do not exist in small sizes. We have used 1-L modular HFMBs in the past, but the need to perform rapid testing has led us to consider even smaller systems. To address this, we designed and built 125-mL, rectangular reactors, which we have called the Fiber Attachment Module Experiment (FAME) system. A polycarbonate rack of four square modules was developed with each module containing removable hollow fibers. Each FAME reactor is self-contained and can be easily plumbed with peristaltic and syringe pumps for continuous recycling of fluids and feeding, as well as fitted with sensors for monitoring pH, dissolved oxygen, and gas measurements similar to their larger counterparts. The first application tested in the FAME racks allowed analysis of over a dozen fiber surface treatments and three inoculation sources to achieve rapid reactor startup and biofilm attachment (based on carbon oxidation and nitrification of wastewater). With these miniature FAME reactors, data for this multi-factorial test were collected in duplicate over a six-month period; this greatly compressed time period required for gathering data needed to study and improve bioreactor performance.

  4. Quantification of chemical mixture interactions modulating dermal absorption using a multiple membrane fiber array.

    Science.gov (United States)

    Baynes, Ronald E; Xia, Xin Rui; Imran, Mudassar; Riviere, Jim E

    2008-03-01

    Dermal exposures to chemical mixtures can potentially increase or decrease systemic bioavailability of toxicants in the mixture. Changes in dermal permeability can be attributed to changes in physicochemical interactions between the mixture, the skin, and the solute of interest. These physicochemical interactions can be described as changes in system coefficients associated with molecular descriptors described by Abraham's linear solvation energy relationship (LSER). This study evaluated the effects of chemical mixtures containing either a solvent (ethanol) or a surfactant (sodium lauryl sulfate, SLS) on solute permeability and partitioning by quantifying changes in system coefficients in skin and a three-membrane-coated fiber (MCF) system, respectively. Regression analysis demonstrated that changes in system coefficients in skin were strongly correlated ( R2 = 0.89-0.98) to changes in system coefficients in the three-membrane MCF array with mixtures containing either 1% SLS or 50% ethanol. The PDMS fiber appeared to play a significant role (R2 = 0.84-0.85) in the MCF array in predicting changes in solute permeability, while the WAX fiber appeared to contribute less (R2 = 0.59-0.77) to the array than the other two fibers. On the basis of changes in system coefficients that are part of a LSER, these experiments were able to link physicochemical interactions in the MCF with those interactions in skin when either system is exposed to 1% SLS or 50% ethanol. These experiments further demonstrated the utility of a MCF array to adequately predict changes in dermal permeability when skin is exposed to mixtures containing either a surfactant or a solvent and provide some insight into the nature of the physiochemical interactions that modulate dermal absorptions.

  5. Mathematic Model of Unsteady Penetration Mass Transfer in Randomly Packed Hollow Fiber Membrane Module

    Institute of Scientific and Technical Information of China (English)

    张秀莉; 张泽廷; 张卫东; 郝欣

    2004-01-01

    Based on the membrane-based absorption experiment of CO2 into water, shell-side flow distribution and mass transfer in a randomly packed hollow fiber module have been analyzed using subchannel model and unsteady penetration mass transfer theory. The cross section of module is subdivided into many small cells which contains only one hollow-fiber. The cross sectional area distribution of these cells is presented by the normal probability density distribution function. It has been obtained that there was a most serious non-ideal flow in shell side at moderate mean packing density, and the large amount of fluid flowed and transferred mass through a small number of large voids. Thus mass transfer process is dominated by the fluid through the larger void area. The mass transfer process in each cell is described by the unsteady penetration theory. The overall mass transfer coefficient equals to the probability addition of the mean mass transfer coefficient in each cell. The comparisons of the values calculated by the model established with the empirical correlations and the experimental data of this work have been done.The predicted overall mass transfer coefficients are in good agreement with experimental data.

  6. DEMONSTRATION OF PILOT-SCALE PERVAPORATION SYSTEMS FOR VOLATILE ORGANIC COMPOUND REMOVAL FROM A SURFACTANT ENHANCED AQUIFER REMEDIATION FLUID. II. HOLLOW FIBER MEMBRANE MODULES

    Science.gov (United States)

    Pilot-scale demonstration of pervaporation-based removal of volatile organic compounds from a surfactant enhanced aquifer remediation (SEAR) fluid has been conducted at USEPA's Test & Evaluation Facility using hollow fiber membrane modules. The membranes consisted of microporous...

  7. Synchronization modulation of Na/K pump molecules can hyperpolarize the membrane resting potential in intact fibers.

    Science.gov (United States)

    Chen, Wei; Dando, Robin

    2007-02-01

    Previously, we have theoretically studied the possibility of electrical rhythmic entrainment of carrier-mediated ion transporters, and experimentally realized synchronization and acceleration of the Na/K pumping rate in the cell membrane of skeletal muscle fibers by a specially designed synchronization modulation electric field. In these studies we either used cut fibers under a voltage clamp or intact fibers, but in the presence of ion channels blockers. A question remained as to whether the field-induced activation observed in the pump molecules could effectively increase the intracellular ionic concentration and the membrane potential at physiological conditions. In this paper, we studied the effects of the field on intact fibers without any channel blockers. We monitored the field-induced changes in the ionic concentration gradient across the cell membrane and the membrane potential non-invasively by using a fluorescent probe and confocal microscopic imaging techniques. The results clearly show that the entrainment of the pump molecules by the synchronization modulation electric field can effectively increase the ionic concentration gradient, and hence, hyperpolarize the membrane potential.

  8. Osmotic Power Generation by Inner Selective Hollow Fiber Membranes: An investigation of thermodynamics, mass transfer, and module scale modelling

    KAUST Repository

    Xiong, Jun Ying

    2016-12-29

    A comprehensive analysis of fluid motion, mass transport, thermodynamics and power generation during pressure retarded osmotic (PRO) processes was conducted. This work aims to (1) elucidate the fundamental relationship among various membrane properties and operation parameters and (2) analyse their individual and combined impacts on PRO module performance. A state-of-the-art inner-selective thin-film composite (TFC) hollow fiber membrane was employed in the modelling. The analyses of mass transfer and Gibbs free energy of mixing indicate that the asymmetric nature of hollow fibers results in more significant external concentration polarization (ECP) in the lumen side of the inner-selective hollow fiber membranes. In addition, a trade-off relationship exists between the power density (PD) and the specific energy (SE). The PD vs. SE trade-off upper bound may provide a useful guidance whether the flowrates of the feed and draw solutions should be further optimized in order to (1) minimize the boundary thickness and (2) maximize the osmotic power generation. Two new terms, mass transfer efficiency and power harvesting efficiency for osmotic power generation, have been proposed. This work may provide useful insights to design and operate PRO modules with enhanced performance so that the PRO process becomes more promising in real applications in the near future.

  9. Fiber Attachment Module Experiment (FAME): Using a Multiplexed Miniature Hollow Fiber Membrane Bioreactor Solution for Rapid Process Testing

    Science.gov (United States)

    Coutts, Janelle L.; Lunn, Griffin M.; Koss, Lawrence L.; Hummerick, Mary E.; Spencer, Lachelle E.; Johnsey, Marissa N.; Richards, Jeffrey T.; Ellis, Ronald; Birmele, Michele N.; Wheeler, Raymond M.

    2014-01-01

    Bioreactor research is mostly limited to continuous stirred-tank reactors (CSTRs) which are not an option for microgravity (g) applications due to the lack of a gravity gradient to drive aeration as described by the Archimedes principle. Bioreactors and filtration systems for treating wastewater in g could avoid the need for harsh pretreatment chemicals and improve overall water recovery. Solution: Membrane Aerated Bioreactors (MABRs) for g applications, including possible use for wastewater treatment systems for the International Space Station (ISS).

  10. Amplitude-modulated fiber-ring laser

    DEFF Research Database (Denmark)

    Caputo, J. G.; Clausen, Carl A. Balslev; Sørensen, Mads Peter

    2000-01-01

    Soliton pulses generated by a fiber-ring laser are investigated by numerical simulation and perturbation methods. The mathematical modeling is based on the nonlinear Schrödinger equation with perturbative terms. We show that active mode locking with an amplitude modulator leads to a self-starting......Soliton pulses generated by a fiber-ring laser are investigated by numerical simulation and perturbation methods. The mathematical modeling is based on the nonlinear Schrödinger equation with perturbative terms. We show that active mode locking with an amplitude modulator leads to a self......-starting of stable solitonic pulses from small random noise, provided the modulation depth is small. The perturbative analysis leads to a nonlinear coupled return map for the amplitude, phase, and position of the soliton pulses circulating in the fiber-ring laser. We established the validity of this approach...

  11. Amplitude-modulated fiber-ring laser

    DEFF Research Database (Denmark)

    Caputo, J. G.; Clausen, Carl A. Balslev; Sørensen, Mads Peter

    2000-01-01

    Soliton pulses generated by a fiber-ring laser are investigated by numerical simulation and perturbation methods. The mathematical modeling is based on the nonlinear Schrödinger equation with perturbative terms. We show that active mode locking with an amplitude modulator leads to a self-starting......Soliton pulses generated by a fiber-ring laser are investigated by numerical simulation and perturbation methods. The mathematical modeling is based on the nonlinear Schrödinger equation with perturbative terms. We show that active mode locking with an amplitude modulator leads to a self......-starting of stable solitonic pulses from small random noise, provided the modulation depth is small. The perturbative analysis leads to a nonlinear coupled return map for the amplitude, phase, and position of the soliton pulses circulating in the fiber-ring laser. We established the validity of this approach...

  12. The development of polymer membranes and modules for air separation

    Science.gov (United States)

    Vinogradov, N. E.; Kagramanov, G. G.

    2016-09-01

    Technology of hollow fiber membrane and modules for air separation was developed. Hollow fibers from the polyphenylene oxide (PPO) having a diameter of 500 μm were obtained. The permeability of the fibers by oxygen was up to 250 Ba, while the separation factor by O2/N2 was 4.3. The membrane module has been made by using these fibers and tested for permeability of individual gases.

  13. Preliminary characterization of carbon dioxide transfer in a hollow fiber membrane module as a possible solution for gas-liquid transfer in microgravity conditions

    Science.gov (United States)

    Farges, Bérangère; Duchez, David; Dussap, Claude-Gilles; Cornet, Jean-François

    2012-01-01

    In microgravity, one of the major challenge encountered in biological life support systems (BLSS) is the gas-liquid transfer with, for instance, the necessity to provide CO2 (carbon source, pH control) and to recover the evolved O2 in photobioreactors used as atmosphere bioregenerative systems.This paper describes first the development of a system enabling the accurate characterization of the mass transfer limiting step for a PTFE membrane module used as a possible efficient solution to the microgravity gas-liquid transfer. This original technical apparatus, together with a technical assessment of membrane permeability to different gases, is associated with a balance model, determining thus completely the CO2 mass transfer problem between phases. First results are given and discussed for the CO2 mass transfer coefficient kLCO obtained in case of absorption experiments at pH 8 using the hollow fiber membrane module. The consistency of the proposed method, based on a gas and liquid phase balances verifying carbon conservation enables a very accurate determination of the kLCO value as a main limiting step of the whole process. Nevertheless, further experiments are still needed to demonstrate that the proposed method could serve in the future as reference method for mass transfer coefficient determination if using membrane modules for BLSS in reduced or microgravity conditions.

  14. CO{sub 2} capture and enrichment by novel hollow fiber facilitated transport membrane module with low energy consumption

    Energy Technology Data Exchange (ETDEWEB)

    Masaaki Teramoto; Satoshi Kitada; Satoshi Shimizu; Nobuaki Ohnishi; Hideto Matsuyama; Norifumi Matsumiya; Miho Nakamura; Kazuhiro Okabe; Hiroshi Mano [Kyoto Institute of Technology, Kyoto (Japan)

    2005-07-01

    A novel facilitated transport membrane module for gas separation is proposed in which a carrier solution is forced to permeate the membrane. Both a feed gas and a carrier solution are supplied to the feed side (high pressure side) of the capillary ultrafiltration membrane module and flow upward. Most of the carrier solution which contains dissolved CO{sub 2} permeates the membrane to the permeate side (low-pressure side), where the solution liberates CO{sub 2} to become a lean solution, and the lean solution is returned to the lumen of the capillary module by a pump. In this study, we performed experiments at several operational conditions by using diethanolamine (DEA) and 2,3-diaminopropionic acid (DAPA) as carriers. The feed side pressure was about 1 atm and the permeate side pressure was about 0.05 atm. CO{sub 2} in the feed gas was successfully enriched to 97.1-99.9% by one-stage separation. When the CO{sub 2} mole fraction in the feed was 0.05, the CO{sub 2} permeance and the CO{sub 2}/N{sub 2} selectivity were 8.9-9.4 x 10{sup -4} mol m{sup -2} s{sup -1} kPa{sup -1} and 1020-2320, respectively, and the CO{sub 2} recovery was 72-76 %. The energy required for CO{sub 2} capture, enrichment and liquefaction was about 0.27kWh kgCO{sub 2}{sup -1}, which is much lower than those by using polymeric membranes, conventional gas absorption processes consisting of absorption and stripping column. The proposed process is promising for the CO{sub 2} recovery with low energy consumption. 6 refs., 4 figs., 1 tab.

  15. Green hydrophilic modification of PE hollow fiber membranes in a module scale via long-distance and dynamic low-temperature H2O plasma flow

    Science.gov (United States)

    Li, Mei-Sheng; Zhao, Zhi-Ping; Wang, Ming-Xing

    2016-11-01

    A green chemistry process, long-distance and dynamic low-temperature (LDDLT) H2O plasma, was developed to modify PE hollow fiber membranes in a module scale using our modified LDDLT plasma setup. The modification degree of LDDLT-H2O plasma was 2 times greater than that of Ar plasma, but the effective treatment distance achieved by LDDLT-Ar plasma was about two times of that obtained by LDDLT-H2O plasma (22 cm). Under the suitable conditions, the effective treatment distance can reach over 54 cm after LDDLT-H2O plasma treatment from the double inlets, closed to some industrial module sizes. The improvement in surface hydrophilicity was because of the introduction of numerous oxygen-containing groups. High concentrations of OH radicals in H2O plasma played a major role in the membrane surface hydroxylation. This directly resulted in a great enhancement in the pure water flux. It increased from about 6 L m-2 h-1 to 45 L m-2 h-1 after treatment. Also, the H2O plasma-treated membrane module exhibited good hydrophilic stability during 285 days storage.

  16. Solid-state membrane module

    Science.gov (United States)

    Gordon, John Howard; Taylor, Dale M.

    2011-06-07

    Solid-state membrane modules comprising at least one membrane unit, where the membrane unit has a dense mixed conducting oxide layer, and at least one conduit or manifold wherein the conduit or manifold comprises a dense layer and at least one of a porous layer and a slotted layer contiguous with the dense layer. The solid-state membrane modules may be used to carry out a variety of processes including the separating of any ionizable component from a feedstream wherein such ionizable component is capable of being transported through a dense mixed conducting oxide layer of the membrane units making up the membrane modules. For ease of construction, the membrane units may be planar.

  17. Fiber Acousto-Electro-Optic Modulator

    Institute of Scientific and Technical Information of China (English)

    Anen; Jiang

    2003-01-01

    A new kind of fiber acousto-electro-optic modulator is made by using Lithium Niobate crystal. This kind of modulator can be used in fiber communication, and its center frequency can be changed by directed current voltages.

  18. Polyazole hollow fiber membranes for direct contact membrane distillation

    KAUST Repository

    Maab, Husnul

    2013-08-07

    Porous hollow fiber membranes were fabricated from fluorinated polyoxadiazole and polytriazole by a dry-wet spinning method for application in desalination of Red Sea water by direct contact membrane distillation (DCMD). The data were compared with commercially available hollow fiber MD membranes prepared from poly(vinylidene fluoride). The membranes were characterized by electron microscopy, liquid entry pressure (LEP), and pore diameter measurements. Finally, the hollow fiber membranes were tested for DCMD. Salt selectivity as high as 99.95% and water fluxes as high as 35 and 41 L m -2 h-1 were demonstrated, respectively, for polyoxadiazole and polytriazole hollow fiber membranes, operating at 80 C feed temperature and 20 C permeate. © 2013 American Chemical Society.

  19. Air Separation Using Hollow Fiber Membranes

    Science.gov (United States)

    Huang, Stephen E.

    2004-01-01

    The NASA Glenn Research Center in partnership with the Ohio Aerospace Institute provides internship programs for high school and college students in the areas of science, engineering, professional administrative, and other technical areas. During the summer of 2004, I worked with Dr. Clarence T. Chang at NASA Glenn Research Center s combustion branch on air separation using hollow fiber membrane technology. . In light of the accident of Trans World Airline s flight 800, FAA has mandated that a suitable solution be created to prevent the ignition of fuel tanks in aircrafts. In order for any type of fuel to ignite, three important things are needed: fuel vapor, oxygen, and an energy source. Two different ways to make fuel tanks less likely to ignite are reformulating the fuel to obtain a lower vapor pressure for the fuel and or using an On Board Inert Gas Generating System (OBIGGS) to inert the Central Wing Tank. goal is to accomplish the mission, which means that the Air Separation Module (ASM) tends to be bulky and heavy. The primary goal for commercial aviation companies is to transport as much as they can with the least amount of cost and fuel per person, therefore the ASM must be compact and light as possible. The plan is to take bleed air from the aircraft s engines to pass air through a filter first to remove particulates and then pass the air through the ASM containing hollow fiber membranes. In the lab, there will be a heating element provided to simulate the temperature of the bleed air that will be entering the ASM and analysis of the separated air will be analyzed by a Gas Chromatograph/Mass Spectrometer (GC/MS). The GUMS will separate the different compounds in the exit streams of the ASM and provide information on the performance of hollow fiber membranes. Hopefully I can develop ways to improve efficiency of the ASM. different types of jet fuel were analyzed and data was well represented on SAE Paper 982485. Data consisted of the concentrations of over

  20. PVDF hollow fiber and nanofiber membranes for fresh water reclamation using membrane distillation

    KAUST Repository

    Francis, Lijo

    2013-11-26

    Polyvinylidene fluoride hollow fiber and nanofibrous membranes are engineered and successfully fabricated using dry-jet wet spinning and electrospinning techniques, respectively. Fabricated membranes are characterized for their morphology, average pore size, pore size distribution, nanofiber diameter distribution, thickness, and water contact angle. Direct contact membrane distillation (DCMD) performances of the fabricated membranes have been investigated using a locally designed and fabricated, fully automated MD bench scale unit and DCMD module. Electrospun nanofibrous membranes showed a water flux as high as 36 L m-2 h-1 whereas hollow fiber membranes showed a water flux of 31.6 L m-2 h-1, at a feed inlet temperature of 80 °C and at a permeate inlet temperature of 20 °C.

  1. Hollow-fiber-supported liquid membranes with improved stability for nitrate removal

    NARCIS (Netherlands)

    Kemperman, A.J.B.; Rolevink, H.H.M.; Boomgaard, van den Th.; Strathmann, H.

    1997-01-01

    This paper describes the development of a hollow-fiber-supported liquid membrane (HFSLM) for the removal of nitrate ions from water. Two different membrane modules were designed which differed in length of the fibers. In order to test the HFSLMs on nitrate flux and stability, two set-ups were used:

  2. Characterization of carbon dioxide transfer in a hollow fiber membrane module as a solution for gas-liquid transfer in microgravity conditions.

    Science.gov (United States)

    Farges, Berangere; Duchez, David; Dussap, Claude-Gilles; Cornet, Jean-F.

    In microgravity, one of the major difficulties encountered in closed photosynthetic reactors is the gas-liquid transfer with the necessity to provide CO2 (carbon source, pH control) and to recover the produced O2 . Indeed, reduced gravity is expected to modify gas liquid transfer and liquid phase mixing characteristics inside photobioreactors conceived to regenerate atmosphere of closed life-support systems. To obtain efficient mass transfer conditions and mixing of phases, several solutions are possible: use of rotating reactor (centrifugal field), use of forced, co-current convective reactor with gas-liquid separator and use of membrane modules. In terms of space process engineering, the membrane reactor can be a valuable alternative in which the gas and liquid phases are separated with a selectively permeable membrane. The rate-limiting factors in this reactor were demonstrated to be the surface of membrane A needed for diffusion of gases and the CO2 and O2 mass transfer coefficients in the liquid phase kL. How-ever, the major advantages of the membrane reactor are that it is composed of a hydrophobic membrane (here PTFE) which showed a high hydrophobicity, an important chemical resis-tance, a very long term stability and overall which is favourable to gas transfer. Moreover, the volumetric mass transfer coefficients are sufficiently high to build compact systems with small footprints, no complex rotating devices and lighter weights. This paper describes first the development of a system enabling the accurate characterization of the mass transfer limiting step for a PTFE membrane module. This original technical apparatus, together with a technical assessment of membrane permeability to different gases, is associated with a balance model, determining thus completely the CO2 mass transfer problem between phases. First results are given and discussed for the CO2 mass transfer coefficient CO kL 2 obtained in case of an absorption experiment at pH = 8 using the

  3. Enhanced Membrane Treatment for Hollow-Fiber Microfiltration in Ultrasonic Reflection Field

    Science.gov (United States)

    Kobayashi, Takaomi; Hosaka, Yoho

    2003-05-01

    The effect of ultrasound on the enhanced membrane treatment process was controlled by the reflection of 28 kHz ultrasound onto the vicinity of a hollow-fiber microfiltration membrane. When a stainless reflection plate was placed behind the membrane module, the resultant permeation flux of the membrane was changed in the ultrasonic reflection field. We found that a semicylindrical reflection plate could highly enhance the membrane cleaning process.

  4. Development of a novel membrane aerated hollow-fiber microbioreactor.

    Science.gov (United States)

    Villain, Louis; Meyer, Lina; Kroll, Stephen; Beutel, Sascha; Scheper, Thomas

    2008-01-01

    A new challenge in biotechnological processes is the development of flexible bioprocessing platforms, allowing strain selection, facilitating scale-up and integrating separation steps. Miniaturization of such a cultivation system allows parallel use and the saving of resources but makes the supply of oxygen to the cells difficult. In this work we present a membrane aerated hollow-fiber microbioreactor (HFMBR) which consists of an acrylic glass module equipped with two different types of membrane fibers. Fibers of polyethersulfone and polyvinyldifluoride were used for substrate and oxygen supply, respectively. Cultivation of E. coli as model organism and production of His-tagged GFP were carried out in the extracapillary space of the membrane aerated HFMBR and compared with cultivations in shaking flask which are commonly used for screening experiments. The measurement of the oxygen transfer capacity and the online monitoring of the dissolved oxygen during the cultivation were performed using a fiber optic oxygen sensor. Online measurement of the optical density was also integrated to the bioreactor. Due to efficient oxygen transfer, a better cell growth than in the shaking flask experiments was achieved, while no negative influence on the GFP productivity was observed in the membrane aerated bioreactor. Thus the feasibility of a future integrated downstreaming could also be demonstrated.

  5. Ion transport membrane module and vessel system

    Science.gov (United States)

    Stein, VanEric Edward; Carolan, Michael Francis; Chen, Christopher M.; Armstrong, Phillip Andrew; Wahle, Harold W.; Ohrn, Theodore R.; Kneidel, Kurt E.; Rackers, Keith Gerard; Blake, James Erik; Nataraj, Shankar; van Doorn, Rene Hendrik Elias; Wilson, Merrill Anderson

    2008-02-26

    An ion transport membrane system comprising (a) a pressure vessel having an interior, an exterior, an inlet, and an outlet; (b) a plurality of planar ion transport membrane modules disposed in the interior of the pressure vessel and arranged in series, each membrane module comprising mixed metal oxide ceramic material and having an interior region and an exterior region, wherein any inlet and any outlet of the pressure vessel are in flow communication with exterior regions of the membrane modules; and (c) one or more gas manifolds in flow communication with interior regions of the membrane modules and with the exterior of the pressure vessel.The ion transport membrane system may be utilized in a gas separation device to recover oxygen from an oxygen-containing gas or as an oxidation reactor to oxidize compounds in a feed gas stream by oxygen permeated through the mixed metal oxide ceramic material of the membrane modules.

  6. Microfiltration : membrane development and module design

    NARCIS (Netherlands)

    Roesink, Hendrik Dirk Willem

    1989-01-01

    This thesis describes the development of a new type of hydrophilic microfiltration membranes and in addition some studies are presented, that may result in a completely new design of microfiltration modules containing capillary membranes.

  7. Microfiltration: Membrane development and module design

    Science.gov (United States)

    Roesink, Hendrik Dirk Willem

    The development of a type of hydrophilic microfiltration membranes is described. Studies which may result in a design of microfiltration modules containing capillary membranes are presented. The membranes are prepared from a solution containing two polymers and are of flat or cylindrical geometry. Attention is focused an capillary membranes, which are tubular membranes of outer diameter 0.5 to 5 mm, prepared by means of a dry-wet spining process. Different flow conditions of the feed suspension in the modules are described. The most favorable configuration appears to be transverse flow. A model to calculate the pressure drop in the bore of the capillary membrane during filtration and backflushing is presented.

  8. Membrane Cholesterol Modulates Superwarfarin Toxicity

    Energy Technology Data Exchange (ETDEWEB)

    Marangoni, M. Natalia; Martynowycz, Michael W.; Kuzmenko, Ivan; Braun, David; Polak, Paul E.; Weinberg, Guy; Rubinstein, Israel; Gidalevitz, David; Feinstein, Douglas L.

    2016-04-26

    Superwarfarins are modified analogs of warfarin with additional lipophilic aromatic rings, up to 100-fold greater potency, and longer biological half-lives. We hypothesized that increased hydrophobicity allowed interactions with amphiphilic membranes and modulation of biological responses. We find that superwarfarins brodifacoum and difenacoum increase lactate production and cell death in neuroblastoma cells. In contrast, neither causes changes in glioma cells that have higher cholesterol content. After choleterol depletion, lactate production was increased and cell viability was reduced. Drug-membrane interactions were examined by surface X-ray scattering using Langmuir monolayers of dipalmitoylphosphatidylcholine and/or cholesterol. Specular X-ray reflectivity data revealed that superwarfarins, but not warfarin, intercalate between dipalmitoylphosphatidylcholine molecules, whereas grazing incidence X-ray diffraction demonstrated changes in lateral crystalline order of the film. Neither agent showed significant interactions with monolayers containing >20% cholesterol. These findings demonstrate an affinity of superwarfarins to biomembranes and suggest that cellular responses to these agents are regulated by cholesterol content.

  9. Fouling behavior of microstructured hollow fiber membranes in submerged and aerated filtrations.

    Science.gov (United States)

    Culfaz, P Z; Wessling, M; Lammertink, R G H

    2011-02-01

    The performance of microstructured hollow fiber membranes in submerged and aerated systems was investigated using colloidal silica as a model foulant. The microstructured fibers were compared to round fibers and to twisted microstructured fibers in flux-stepping experiments. The fouling resistances in the structured fibers were found to be higher than those of round fibers. This was attributed to stagnant zones in the grooves of the structured fibers. As the bubble sizes were larger than the size of the grooves of the structured fibers, it is possible that neither the bubbles nor the secondary flow caused by the bubbles can reach the bottom parts of the grooves. Twisting the structured fibers around their axes resulted in decreased fouling resistances. Large, cap-shaped bubbles and slugs were found to be the most effective in fouling removal, while small bubbles of sizes similar to the convolutions in the structured fiber did not cause an improvement in these fibers. Modules in a vertical orientation performed better than horizontal modules when coarse bubbling was used. For small bubbles, the difference between vertical and horizontal modules was not significant. When the structured and twisted fibers were compared to round fibers with respect to the permeate flowrate produced per fiber length instead of the actual flux through the convoluted membrane area, they showed lower fouling resistance than round fibers. This is because the enhancement in surface area is more than the increase in resistance caused by stagnant zones in the grooves of the structured fibers. From a practical point of view, although the microstructure does not promote further turbulence in submerged and aerated systems, it can still be possible to enhance productivity per module with the microstructured fibers due to their high surface area-to-volume ratio.

  10. Mathematic Model of Unsteady Penetration Mass Transfer in Randomly Packed Hollow Fiber Membrane Module%随机填充中空纤维膜组件中非稳态渗透传质数学模型

    Institute of Scientific and Technical Information of China (English)

    张秀莉; 张泽廷; 张卫东; 郝欣

    2004-01-01

    Based on the membrane-based absorption experiment of C02 into water, shell-side flow distribution and mass transfer in a randomly packed hollow fiber module have been analyzed using subchannel model and unsteady penetration mass transfer theory. The cross section of module is subdivided into many small cells which contains only one hollow-fiber. The cross sectional area distribution of these cells is presented by the normal probability density distribution function. It has been obtained that there was a most serious non-ideal flow in shell side at moderate mean packing density, and the large amount of fluid flowed and transferred mass through a small number of large voids. Thus mass transfer process is dominated by the fluid through the larger void area. The mass transfer process in each cell is described by the unsteady penetration theory. The overall mass transfer coefficient equals to the probability addition of the mean mass transfer coefficient in each cell. The comparisons of the values calculated by the model established with the empirical correlations and the experimental data of this work have been done.The predicted overall mass transfer coefficients are in good agreement with experimental data.

  11. Hollow Fiber Membrane Dehumidification Device for Air Conditioning System.

    Science.gov (United States)

    Zhao, Baiwang; Peng, Na; Liang, Canzeng; Yong, Wai Fen; Chung, Tai-Shung

    2015-11-16

    In order to provide a comfortable living and working environment indoors in tropical countries, the outdoor air often needs to be cooled and dehumidified before it enters the rooms. Membrane separation is an emerging technology for air dehumidification and it is based on the solution diffusion mechanism. Water molecules are preferentially permeating through the membranes due to its smaller kinetic diameter and higher condensability than the other gases. Compared to other dehumidification technologies such as direct cooling or desiccation, there is no phase transition involved in membrane dehumidification, neither the contact between the fresh air stream and the desiccants. Hence, membrane dehumidification would not only require less energy consumption but also avoid cross-contamination problems. A pilot scale air dehumidification system is built in this study which comprises nine pieces of one-inch PAN/PDMS hollow fiber membrane modules. A 150 h long-term test shows that the membrane modules has good water vapor transport properties by using a low vacuum force of only 0.78 bar absolute pressure at the lumen side. The water vapor concentration of the feed humid air decreases dramatically from a range of 18-22 g/m³ to a range of 13.5-18.3 g/m³. Most importantly, the total energy saving is up to 26.2% compared with the conventional air conditioning process.

  12. Hollow Fiber Membrane Dehumidification Device for Air Conditioning System

    Directory of Open Access Journals (Sweden)

    Baiwang Zhao

    2015-11-01

    Full Text Available In order to provide a comfortable living and working environment indoors in tropical countries, the outdoor air often needs to be cooled and dehumidified before it enters the rooms. Membrane separation is an emerging technology for air dehumidification and it is based on the solution diffusion mechanism. Water molecules are preferentially permeating through the membranes due to its smaller kinetic diameter and higher condensability than the other gases. Compared to other dehumidification technologies such as direct cooling or desiccation, there is no phase transition involved in membrane dehumidification, neither the contact between the fresh air stream and the desiccants. Hence, membrane dehumidification would not only require less energy consumption but also avoid cross-contamination problems. A pilot scale air dehumidification system is built in this study which comprises nine pieces of one-inch PAN/PDMS hollow fiber membrane modules. A 150 h long-term test shows that the membrane modules has good water vapor transport properties by using a low vacuum force of only 0.78 bar absolute pressure at the lumen side. The water vapor concentration of the feed humid air decreases dramatically from a range of 18–22 g/m3 to a range of 13.5–18.3 g/m3. Most importantly, the total energy saving is up to 26.2% compared with the conventional air conditioning process.

  13. Preparation of Polyvinylidene Fluoride (PVDF Hollow Fiber Hemodialysis Membranes

    Directory of Open Access Journals (Sweden)

    Qinglei Zhang

    2014-02-01

    Full Text Available In this study, the polyvinylidene fluoride (PVDF hollow fiber hemodialysis membranes were prepared by non-solvent induced phase separation (NIPS. The influences of PVDF membrane thickness and polyethylene glycol (PEG content on membrane morphologies, pore size, mechanical and permeable performance were investigated. It was found that membrane thickness and PEG content affected both the structure and performance of hollow fiber membranes. The tensile strength and rejection of bovine serum albumin (BSA increased with increasing membrane thickness, while the Ultrafiltration flux (UF flux of pure water was the opposite. The tensile strength, porosity and rejection of BSA increased with increasing PEG content within a certain range. Compared with commercial F60S membrane, the PVDF hollow fiber membrane showed higher mechanical and permeable performance. It was proven that PVDF material had better hydrophilicity and lower BSA adsorption, which was more suitable for hemodialysis. All the results indicate that PVDF hollow fiber membrane is promising as a hemodialysis membrane.

  14. Modulation instability in the weak dispersion regime of a dispersion modulated passive fiber-ring cavity.

    Science.gov (United States)

    Copie, François; Conforti, Matteo; Kudlinski, Alexandre; Trillo, Stefano; Mussot, Arnaud

    2017-05-15

    We present a theoretical and experimental study of the modulation instability process in a dispersion oscillating passive fiber-ring resonator in the low dispersion region. Generally, the modulation of the dispersion along the cavity length is responsible for the emergence of a regime characterised by multiple parametric resonances (or Faraday instabilities). We show that, under weak dispersion conditions, a huge number of Faraday sidebands can grow under the influence of fourth order dispersion. We specifically designed a piecewise uniform fiber-ring cavity and report on experiments that confirm our theoretical predictions. We recorded the dynamics of this system revealing strong interactions between the different sidebands in agreement with numerical simulations.

  15. Electromechanical behavior of fiber-reinforced dielectric elastomer membrane

    Directory of Open Access Journals (Sweden)

    Chi Li

    2015-04-01

    Full Text Available Based on its large deformation, light weight, and high energy density, dielectric elastomer (DE has been used as driven muscle in many areas. We design the fiber-reinforced DE membrane by adding fibers in the membrane. The deformation and driven force direction of the membrane can be tuned by changing the fiber arrangements. The actuation in the perpendicular direction of the DE membrane with long fibers first increases and then decreases by the increasing of the fiber spacing in the perpendicular direction. The horizontal actuation of the membrane decreases by decreasing the spacing of short fibers. In the membrane-inflating structure, the radially arranged fibers will break the axisymmetric behavior of the structure. The top area of the inflated balloon without fiber will buckle up when the voltage reaches a certain level. Finite element simulations based on nonlinear field theory are conducted to investigate the effects of fiber arrangement and verify the experimental results. This work can guide the design of fiber-reinforced DE.

  16. Synthesis of polypiperazine-amide thin-film membrane on PPESK hollow fiber UF membrane

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    A new interfacial polymerization (IP) procedure is developed in order to synthesize polypiperazine-amide thin-film membrane on the inner surface of poly(phthalazinone ether sulfone ketone) (PPESK) hollow fiber ultrafiltration (UF) membrane. A hollow fiber composite membrane with good performance was prepared and studied by FT-IR and scanning electron microscopy.

  17. Polymeric hollow fiber membranes for bioartificial organs and tissue engineering applications

    NARCIS (Netherlands)

    Diban Ibrahim Gomez, N.; Stamatialis, D.

    2014-01-01

    Polymeric hollow fiber (HF) membranes are commercially available, i.e. microfiltration and ultrafiltration cartridges or reverse osmosis and gas separation modules, to be applied for separation purposes in industry, for instance to recover valuable raw materials or products, or for the treatment of

  18. Dehydration of Ethanol-Water Mixture by Pervaporation using Poly(amide-imide) Hollow Fiber Membrane

    National Research Council Canada - National Science Library

    Shinsuke TAKEGAMI; TUJII, Hideki YAMADA

    1993-01-01

    ..... The heat treament at 265 °C gives a high separation factor of water to ethanol. The module having a membrane surface of 1 m2 was prepared by binding the hollow fibers of 3000pieces and potting in potting resin...

  19. Sulfonated polystyrene fiber network-induced hybrid proton exchange membranes.

    Science.gov (United States)

    Yao, Yingfang; Ji, Liwen; Lin, Zhan; Li, Ying; Alcoutlabi, Mataz; Hamouda, Hechmi; Zhang, Xiangwu

    2011-09-01

    A novel type of hybrid membrane was fabricated by incorporating sulfonated polystyrene (S-PS) electrospun fibers into Nafion for the application in proton exchange membrane fuel cells. With the introduction of S-PS fiber mats, a large amount of sulfonic acid groups in Nafion aggregated onto the interfaces between S-PS fibers and the ionomer matrix, forming continuous pathways for facile proton transport. The resultant hybrid membranes had higher proton conductivities than that of recast Nafion, and the conductivities were controlled by selectively adjusting the fiber diameters. Consequently, hybrid membranes fabricated by ionomers, such as Nafion, incorporated with ionic-conducting nanofibers established a promising strategy for the rational design of high-performance proton exchange membranes.

  20. Soliton modulation instability in fiber lasers

    Science.gov (United States)

    Tang, D. Y.; Zhao, L. M.; Wu, X.; Zhang, H.

    2009-08-01

    We report experimental evidence of soliton modulation instability in erbium-doped fiber lasers. An alternate type of spectral sideband generation was always experimentally observed on the soliton spectrum of the erbium-doped soliton fiber lasers when energy of the formed solitons reached beyond a certain threshold value. Following this spectral sideband generation, if the pump power of the lasers was further increased, either a new soliton would be formed or the existing solitons would experience dynamical instabilities, such as the period-doubling bifurcations or period-doubling route to chaos. We point out that the mechanism for this soliton spectral sideband generation is the modulation instability of the solitons in the lasers. We further show that, owing to the internal energy balance of a dissipative soliton, modulation instability itself does not destroy the stable soliton evolution in a laser cavity. It is the strong resonant wave coupling between the soliton and dispersive waves that leads to the dynamic instability of the solitons.

  1. Fabrication of Polyacrylonitrile Hollow Fiber Membranes from Ionic Liquid Solutions

    KAUST Repository

    Kim, Dooli

    2015-10-08

    The interest in green processes and products has increased to reduce the negative impact of many industrial processes to the environment. Solvents, which play a crucial role in the fabrication of membranes, need to be replaced by sustainable and less toxic solvent alternatives for commonly used polymers. The purpose of this study is the fabrication of greener hollow fiber membranes based on polyacrylonitrile (PAN), substituting dimethylformamide (DMF) by less toxic mixtures of ionic liquids (IL) and dimethylsulfoxide (DMSO). A thermodynamic analysis was conducted, estimating the Gibbs free energy of mixing to find the most convenient solution compositions. Hollow fiber membranes were manufactured and optimized. As a result, a uniform pattern and high porosity were observed in the inner surface of the membranes prepared from the ionic liquid solutions. The membranes were coated with a polyamide layer by interfacial polymerization the hollow fiber membranes were applied in forward osmosis experiments by using sucrose solutions as draw solution.

  2. A Pilot-Scale System for Carbon Molecular Sieve Hollow Fiber Membrane Manufacturing

    KAUST Repository

    Karvan, O.

    2012-12-21

    Carbon molecular sieve (CMS) membranes offer advantages over traditional polymeric membrane materials, but scale-up of manufacturing systems has not received much attention. In the recent decade, there has been a dramatic increase in fundamental research on these materials with a variety of applications being studied. The results from a pilot-scale CMS production system are presented. This system was designed based on extensive laboratory research, and hollow fiber membranes produced in this system show similar performance compared to membranes produced using a smaller bench-scale system. After optimizing the system design, a 93% recovery of the precursor fibers for use in membrane module preparation were obtained. © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  3. Optical fiber sensor for membrane submicrometer vibration measurement.

    Science.gov (United States)

    Prokopczuk, Krzysztof; Rozwadowski, Krzysztof; Aleksandra Starzyńska, M D; Domański, Andrzej W

    2014-09-10

    This paper presents an optical fiber sensor for membrane submicrometer vibration measurement. The sensor is designed ultimately for low-cost medical audiometric applications such as determining the mobility of the tympanic membrane stimulated by the tone. The sensing method is minimally invasive, and the sensing head does not contact the surface of the membrane. Measurements were performed on tympanic membrane phantoms. Deflections of a few nanometers were measured, and vibration maps of phantoms were taken.

  4. Performance of different hollow fiber membranes for seawater desalination using membrane distillation

    KAUST Repository

    Francis, Lijo

    2014-08-11

    Membrane distillation requires a highly porous hydrophobic membrane with low surface energy. In this paper, we compare the direct contact membrane distillation (DCMD) performances of four different types of in-house fabricated hollow fiber membranes and two different commercially available hollow fiber membranes. Hollow fiber membranes are fabricated using wet-jet phase inversion technique and the polymeric matrices used for the fabrication are polyvinylidine fluoride (PVDF) and polyvinyl chloride (PVC). Commercial hollow fiber membrane materials are made of polytetrafluoroethylene (PTFE) and polypropylene (PP). PVDF hollow fibers showed a superior performance among all the hollow fibers tested in the DCMD process and gave a water vapor flux of 31 kg m-2h-1 at a feed and coolant inlet temperatures of 80 and 20°C, respectively. Under the same conditions, the water vapor flux observed for PP, PTFE, and PVC hollow fiber membranes are 13, 11, and 6 kg m-2h-1, respectively, with 99.99% salt rejection observed for all membranes used.

  5. Integrally skinned polysulfone hollow fiber membranes for pervaporation

    NARCIS (Netherlands)

    Koops, G.H.; Nolten, J.A.M.; Mulder, M.H.V.; Smolders, C.A.

    1994-01-01

    From polysulfone as polymer, integrally skinned hollow fiber membranes with a defect-free top layer have been spun. The spinning process described here differs from the traditional dry-wet spinning process where the fiber enters the coagulation bath after passing a certain air gap. In the present pr

  6. Integrally Skinned Polysulfone Hollow Fiber Membranes for Pervaporation

    NARCIS (Netherlands)

    Koops, G.H.; Nolten-Oude Hendrikman, J.A.M.; Nolten, J.A.M.; Mulder, M.H.V.; Smolders, C.A.; Smolders, C.A.

    1994-01-01

    From polysulfone as polymer, integrally skinned hollow fiber membranes with a defect-free top layer have been spun. The spinning process described here differs from the traditional dry-wet spinning process where the fiber enters the coagulation bath after passing a certain air gap. In the present pr

  7. Membrane properties in small cutaneous nerve fibers in humans

    DEFF Research Database (Denmark)

    Hennings, Kristian; Frahm, Ken Steffen; Petrini, Laura;

    2016-01-01

    than large fibers (rmANOVA, Bonferroni, P=0.006). CONCLUSION: This study is a reliable method to investigate the membrane properties of small cutaneous nerve fibers in humans and may be used in clinical settings as a diagnostic or profiling tool. This article is protected by copyright. All rights...

  8. New modulator for the optical signal in a fiber

    Institute of Scientific and Technical Information of China (English)

    ZHANG Tian-hao; JIA Feng; WANG Shun-li; MAN Jiang wei; NIU Kai; WANG Xu-cheng; YANG Jia

    2006-01-01

    A new modulator for the optical signal in a fiber based on multi-beam interference is designed. In the experiment,the distance of a couple of abutted fibers was modulated through a piezoelectric ceramic pipe driven by 50 Hz AC voltage, so that the amplitude of the transmitted optical signal was modulated. The modulation ratio is about 10% ,S/N ratio is about 60 dB and the bandwidth is about 200 KHz.

  9. Spinning of hollow fiber ultrafiltration membranes from a polymer blend

    NARCIS (Netherlands)

    Wienk, I.M.; Wienk, I.M.; Olde scholtenhuis, F.H.A.; van den Boomgaard, Anthonie; Smolders, C.A.; Smolders, C.A.

    1995-01-01

    In this study the dry-wet spinning technique is used for the preparation of hollow fiber membranes. In the polymer solution a blend of two polymers, poly(ether sulfone) and poly(vinyl pyrrolidone), is used. The morphology of the membranes obtained is related to rheological characteristics and phase

  10. Highly permeable and mechanically robust silicon carbide hollow fiber membranes

    NARCIS (Netherlands)

    de Wit, Patrick; Kappert, Emiel; Lohaus, T.; Wessling, Matthias; Nijmeijer, Arian; Benes, Nieck Edwin

    2015-01-01

    Silicon carbide (SiC) membranes have shown large potential for applications in water treatment. Being able to make these membranes in a hollow fiber geometry allows for higher surface-to-volume ratios. In this study, we present a thermal treatment procedure that is tuned to produce porous silicon

  11. Highly permeable and mechanically robust silicon carbide hollow fiber membranes

    NARCIS (Netherlands)

    Wit, de P.; Kappert, Emiel J.; Lohaus, T.; Wessling, M.; Nijmeijer, A.; Benes, N.E.

    2015-01-01

    Silicon carbide (SiC) membranes have shown large potential for applications in water treatment. Being able to make these membranes in a hollow fiber geometry allows for higher surface-to-volume ratios. In this study, we present a thermal treatment procedure that is tuned to produce porous silicon ca

  12. Modulational instability of short pulses in long optical fibers

    DEFF Research Database (Denmark)

    Shukla, P. K.; Juul Rasmussen, Jens

    1986-01-01

    The effect of time-derivative nonlinearity is incorporated into the study of the modulational instability of heat pulses propagating through long optical fibers. Conditions for soliton formation are discussed......The effect of time-derivative nonlinearity is incorporated into the study of the modulational instability of heat pulses propagating through long optical fibers. Conditions for soliton formation are discussed...

  13. Polarization modulation instability in photonic crystal fibers.

    Science.gov (United States)

    Kruhlak, R J; Wong, G K; Chen, J S; Murdoch, S G; Leonhardt, R; Harvey, J D; Joly, N Y; Knight, J C

    2006-05-15

    Polarization modulation instability (PMI) in birefringent photonic crystal fibers has been observed in the normal dispersion regime with a frequency shift of 64 THz between the generated frequencies and the pump frequency. The generated sidebands are orthogonally polarized to the pump. From the observed PMI frequency shift and the measured dispersion, we determined the phase birefringence to be 5.3 x 10(-5) at a pump wavelength of 647.1 nm. This birefringence was used to estimate the PMI gain as a function of pump wavelength. Four-wave mixing experiments in both the normal and the anomalous dispersion regimes generated PMI frequency shifts that show good agreement with the predicted values over a 70 THz range. These results could lead to amplifiers and oscillators based on PMI.

  14. Design and fabrication of inner-selective thin-film composite (TFC) hollow fiber modules for pressure retarded osmosis (PRO)

    KAUST Repository

    Wan, Chun Feng

    2016-08-03

    Pressure retarded osmosis (PRO) is a promising technology to harvest the renewable osmotic energy from salinity gradients. There are great progresses in the fabrication of PRO membranes in the last decade. Thin-film composite (TFC) hollow fibers have been widely studied and demonstrated superior performance. However, the lack of effective TFC hollow fiber modules hinders the commercialization of the PRO technology. Knowledge and experiences to fabricate TFC hollow fiber modules remain limited in the open literature. In this study, we aim to reveal the engineering and science on how to fabricate TFC hollow fiber modules including the formation of inner-selective polyamide layers and the repair of leakages. TFC-PES hollow fiber modules with 30% and 50% packing densities have been successfully fabricated, showing peak power densities of 20.0 W/m2 and 19.4 W/m2, respectively, at 20 bar using 1 M NaCl solution and DI water as feeds. The modules may be damaged during handling and high pressure testing. The repaired modules have a power density of 18.2 W/m2, 91% of the power densities of the undamaged ones. This study would make up the gap between TFC membrane fabrication and TFC membrane module fabrication in the membrane industry. © 2016 Elsevier B.V.

  15. Polymer solution, fiber mat, and nanofiber membrane-electrode-assembly therewith, and method of fabricating same

    DEFF Research Database (Denmark)

    2016-01-01

    In one aspect of the present invention, a fiber mat is provided. The fiber mat includes at least one type of fibers, which includes one or more polymers. The fiber mat may be a single fiber mat which includes one type of fibers, or may be a dual or multi fiber mat which includes multiple types...... of fibers. The fibers may further include particles of a catalyst. The fiber mat may be used to form an electrode or a membrane. In a further aspect, a fuel cell membrane-electrode-assembly has an anode electrode, a cathode electrode, and a membrane disposed between the anode electrode and the cathode...

  16. Block copolymer/homopolymer dual-layer hollow fiber membranes

    KAUST Repository

    Hilke, Roland

    2014-12-01

    We manufactured the first time block copolymer dual-layer hollow fiber membranes and dual layer flat sheet membranes manufactured by double solution casting and phase inversion in water. The support porous layer was based on polystyrene and the selective layer with isopores was formed by micelle assembly of polystyrene-. b-poly-4-vinyl pyridine. The dual layers had an excellent interfacial adhesion and pore interconnectivity. The dual membranes showed pH response behavior like single layer block copolymer membranes with a low flux for pH values less than 3, a fast increase between pH4 and pH6 and a constant high flux level for pH values above 7. The dry/wet spinning process was optimized to produce dual layer hollow fiber membranes with polystyrene internal support layer and a shell block copolymer selective layer.

  17. High Power Fiber Bundle Array Coupled LDA Module

    Institute of Scientific and Technical Information of China (English)

    QU Zhou; LIU Yang; ZHAO Chong-guang; WANG Ji; YIN Hong-he; WANG Li-jun

    2006-01-01

    An optical fiber bundle array coupling module with high output power is presented in this paper. The device integrated the coupling technique of the high power laser diode array (LDA) and the micro-ball lenses fiber array. This module can efficiently couple the output laser of the LDA into 19 fibers array with micro-ball lens endsurface. The difference of the couple efficiency between the flat-end fiber and micro-ball-end fiber is discussed.The micro-ball lenses fiber array made of 19 fibers have the same fiber core diameter of 200 μm, and then the endsurfaces of 19 fibers are fused to 19 micro-ball lenses. The micro-ball lenses fiber array are fixed precisely in the neighborhood on the V-grooves, and the fiber array has the same arrange period with the semiconductor laser units of LDA. This configuration of micro-ball lens fiber array can greatly reduce the divergence of the laser beam from all directions, and a very efficient laser beam homogenizer and shaper are obtained. Finally, high output power of 30.1 W of the fiber coupled LDA is achieved, and the maximal coupling efficiency is >83% with the numeral aperture (NA) of 0.16.

  18. Sandwich-structured hollow fiber membranes for osmotic power generation

    KAUST Repository

    Fu, Feng Jiang

    2015-11-01

    In this work, a novel sandwich-structured hollow fiber membrane has been developed via a specially designed spinneret and optimized spinning conditions. With this specially designed spinneret, the outer layer, which is the most crucial part of the sandwich-structured membrane, is maintained the same as the traditional dual-layer membrane. The inner substrate layer is separated into two layers: (1) an ultra-thin middle layer comprising a high molecular weight polyvinylpyrrolidone (PVP) additive to enhance integration with the outer polybenzimidazole (PBI) selective layer, and (2) an inner-layer to provide strong mechanical strength for the membrane. Experimental results show that a high water permeability and good mechanical strength could be achieved without the expensive post treatment process to remove PVP which was necessary for the dual-layer pressure retarded osmosis (PRO) membranes. By optimizing the composition, the membrane shows a maximum power density of 6.23W/m2 at a hydraulic pressure of 22.0bar when 1M NaCl and 10mM NaCl are used as the draw and feed solutions, respectively. To our best knowledge, this is the best phase inversion hollow fiber membrane with an outer selective PBI layer for osmotic power generation. In addition, this is the first work that shows how to fabricate sandwich-structured hollow fiber membranes for various applications. © 2015 Elsevier B.V.

  19. Preparation and characterization of alumina hollow fiber membranes

    Institute of Scientific and Technical Information of China (English)

    Tao WANG; Yuzhong ZHANG; Guangfen LI; Hong LI

    2009-01-01

    With the rapid development of membrane technology in water treatment, there is a growing demand for membrane products with high performance. The inorganic hollow fiber membranes are of great interest due to their high resistance to abrasion, chemical/thermal degradation, and higher surface area/volume ratio therefore they can be utilized in the fields of water treatment. In this study, the alumina (Al2O3) hollow fiber membranes were prepared by a combined phase-inversion and sintering method. The organic binder solution (dope) containing suspended Al2O3 powders was spun to a hollow fiber precursor, which was then sintered at elevated tempera-tures in order to obtain the Al2O3 hollow fiber membrane. The dope solution consisted ofpolyethersulfone (PES), N-methyl-2-pyrrolidone (NMP) and polyvinylpyrrolidone (PVP), which were used as polymer binder, solvent and additive, respectively. The prepared Al2O3 hollow fiber membranes were characterized by a scanning electron microscope (SEM) and thermal gravimetric analysis (TG). The effects of the sintering temperature and Al2O3/PES ratios on the morphological structure, pure water flux, pore size and porosity of the membranes were also investigated extensively. The results showed that the pure water flux, maximum pore size and porosity of the prepared membranes decreased with the increase in Al2O3/PES ratios and sintering temperature. When the Al2O3/PES ratio reached 9, the pure water flux and maximum pore size were at 2547L/m2·h and 1.4μm, respectively. Under 1600℃ of sintering temperature, the pure water flux and maximum pore size reached 2398 L/(m2·h) and 2.3 μm, respectively. The results showed that the alumina hollow fiber membranes we prepared were suitable for the microfiltration process. The morphology investigation also revealed that the prepared Al2O3 hollow fiber membrane retained its'asymmetric structure even after the sintering process.

  20. Separation of hydrogen from carbon monoxide using a hollow fiber polyimide membrane: experimental and simulation

    Energy Technology Data Exchange (ETDEWEB)

    Peer, M.; Mehdi Kamali, S.; Mahdeyarfar, M.; Mohammadi, T. [Research Laboratory for Separation Processes, Chemical Engineering Department, Tehran (Iran)

    2007-10-15

    The separation of hydrogen from carbon monoxide (syngas ratio adjustment) with polymeric membranes was investigated in this work. A polyimide hollow fiber membrane module was used for hydrogen separation. This polymer has shown large permeability and selectivity for hydrogen separation (selectivity of ca. 30). Permeation tests were carried out at different feed conditions. Feed flow rates were varied between 150-300 mL/min, temperature was varied in the range of 20-80 C and feed pressure was varied between 5-9 bar. Mixtures containing 0-50 % carbon monoxide were used when carrying out experiments. Measured membrane permeances for hydrogen and carbon monoxide were about 70-100 GPU (gas permeation units) and 3-5.5 GPU, respectively. In addition, a mathematical model for simulation of gas separation in hollow fiber membrane modules with all flow patterns (crossflow, countercurrent and cocurrent) was presented. This model can be used for calculation of membrane performance or its required surface area for a specific separation. Experimental results have shown good correlation with simulation results. Plasticization, competitive sorption and concentration polarization effect of carbon monoxide on membrane performance is shown with experimental results. This effect reduced hydrogen permeances in mixed gas experiments. (Abstract Copyright [2007], Wiley Periodicals, Inc.)

  1. Performance of Hollow Fiber Ultrafiltration Membranes in the Clarification of Blood Orange Juice

    Directory of Open Access Journals (Sweden)

    Carmela Conidi

    2015-12-01

    Full Text Available The clarification of blood orange juice by ultrafiltration (UF was investigated by using three hollow fiber membrane modules characterized by different membrane materials (polysulfone (PS and polyacrylonitrile (PAN and molecular weight cut-off (MWCO (50 and 100 kDa. The performance of selected membranes was investigated in terms of productivity and selectivity towards total anthocyanin content (TAC, total phenolic content (TPC, and total antioxidant activity (TAA. All selected membranes allowed a good preservation of antioxidant compounds; however, the most suitable membrane for the clarification of the juice was found to be the PS 100 kDa membrane. In optimized operating conditions this membrane exhibited steady-state fluxes of 7.12 L/m2h, higher than those measured for other investigated membranes. Rejections towards TPC and TAA were of the order of 17.5% and 15%, respectively. These values were lower than those determined for PS 50 kDa and PAN 50 kDa membranes. In addition, the PS 100 kDa membrane exhibited a lower rejection (7.3% towards TAC when compared to the PS 50 kDa membrane (9.2%.

  2. EFFECTS OF PRESSURE AND TEMPERATURE ON ULTRAFILTRATION HOLLOW FIBER MEMBRANE IN MOBILE WATER TREATMENT SYSTEM

    Directory of Open Access Journals (Sweden)

    ROSDIANAH RAMLI

    2016-07-01

    Full Text Available In Sabah, Malaysia, there are still high probability of limited clean water access in rural area and disaster site. Few villages had been affected in Pitas due to improper road access, thus building a water treatment plant there might not be feasible. Recently, Kundasang area had been affected by earthquake that caused water disruption to its people due to the damage in the underground pipes and water tanks. It has been known that membrane technology brought ease in making mobile water treatment system that can be transported to rural or disaster area. In this study, hollow fiber membrane used in a mobile water treatment system due to compact and ease setup. Hollow fiber membrane was fabricated into small module at 15 and 30 fibers to suit the mobile water treatment system for potable water production of at least 80 L/day per operation. The effects of transmembrane pressure (TMP and feed water temperature were investigated. It was found that permeate flux increases by more than 96% for both 15 and 30 fiber bundles with increasing pressure in the range of 0.25 to 3.0 bar but dropped when the pressure reached maximum. Lower temperature of 17 to 18˚C increase the water viscosity by 15% from normal temperature of water at 24˚C, making the permeate flux decreases. The fabricated modules effectively removed 96% turbidity of the surface water sample tested.

  3. WDM Phase-Modulated Millimeter-Wave Fiber Systems

    DEFF Research Database (Denmark)

    Yu, Xianbin; Prince, Kamau; Gibbon, Timothy Braidwood

    2012-01-01

    This chapter presents a computer simulation case study of two typical WDM phase-modulated millimeter-wave systems. The phase-modulated 60 GHz fiber multi-channel transmission systems employ single sideband (SSB) and double sideband subcarrier modulation (DSB-SC) schemes and present one of the lat......This chapter presents a computer simulation case study of two typical WDM phase-modulated millimeter-wave systems. The phase-modulated 60 GHz fiber multi-channel transmission systems employ single sideband (SSB) and double sideband subcarrier modulation (DSB-SC) schemes and present one...... of the latest research efforts in the rapidly emerging Radio-over-Fiber (RoF) application space for in-house access networks....

  4. STRUCTURE AND PROPERTIES OF COMPOSITE POLYURETHANE HOLLOW FIBER MEMBRANES

    Institute of Scientific and Technical Information of China (English)

    Xian-feng Li; Chang-fa Xiao

    2005-01-01

    Composite polyurethane (PU)-SiO2 hollow fiber membranes were successfully prepared via optimizing the technique of dry-jet wet spinning, and their pressure-responsibilities were confirmed by the relationships of pure water fluxtransmembrane pressure (PWF-TP) for the first time. The origin for this phenomenon was analyzed on the basis of membrane structure and material characteristics. The effects of SiO2 content on the structure and properties of membrane were investigated. The experimental results indicated that SiO2 in membrane created a great many interfacial micro-voids and played an important role in pressure-responsibility, PWF and rejection of membrane: with the increase of SiO2 content, the ability of membrane recovery weakened, PWF increased, and rejection decreased slightly.

  5. Hollow fiber membranes with different external corrugated surfaces for desalination by membrane distillation

    Science.gov (United States)

    García-Fernández, Loreto; García-Payo, Carmen; Khayet, Mohamed

    2017-09-01

    Poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP) hollow fiber membranes were prepared using the phase inversion spinning technique under a wet gap mode. Different corrugated outer surfaces were obtained by means of a micro-engineered spinneret, spraying the external coagulant on the nascent fiber along gap, and different spinning parameters, namely, the gap distance and the external coagulant flow rate. A quantitative evaluation of the corrugation size and shape was carried out by electron scanning microscopy and atomic force microscopy. The effect of the corrugation size and shape on the direct contact membrane distillation (DCMD) performance has been studied. The corrugated outer surface acted as micro-turbulence promoters mitigating the temperature polarization effect and enhanced the external effective surface area for condensation. Both factors improved the DCMD permeability of the hollow fiber membranes. However, corrugations with V-shaped valleys depths greater than about 30 μm did not always improve the DCMD permeate flux. It was found that the membrane prepared with the spray wetting mode exhibited the best desalination performance. The salt rejection factor of all prepared hollow fiber membranes was greater than 99.9% and the highest DCMD permeate flux of this study was greater than those reported so far for the PVDF-HFP hollow fiber membranes.

  6. Novel concept for pure diffusive capillary membrane oxygenators: silicone hollow sphere (SiHSp) fibers.

    Science.gov (United States)

    Khachab, Ali; Tabesh, Hadi; Kashefi, Ali; Mottaghy, Khosrow

    2013-01-01

    The preeminent limitation of silicone membrane oxygenators is the poor gas permeability compared with microporous hollow fiber oxygenators (MHFO). However, the imponderability of plasma leakage, foam formation, and brittleness are all hazards that result in blood trauma formation, hereby limiting the application of MHFO during long-term oxygenation therapies. Here, we introduce a novel type of pure diffusive capillary-form silicone membrane called silicone hollow sphere. Silicone hollow sphere walls embed hollow microspheres into the core. The lodging of such microspheres promotes a higher gas exchange performance (as a result of the reduction of dense material) without altering the total thickness of capillary walls; thereby the demanded mechanical strength for handling is nevertheless conserved. Out of the same silicone material, seven SiHSp fibers with six different design specifications and a control were constructed to define experimentally the appropriate configuration for subsequent production. Each fiber was used in a miniaturized module oxygenator of a constant effective membrane surface area (Amem = 0.02 m) and length (L =183 mm) for a fair evaluation. Modules were investigated in vitro with porcine blood. O2 and CO2 transfer rates weighed 12.6 mlO2/min and 10.4 mlCO2/min, respectively, for one type of SiHSp, comparable with microporous polypropylene (OXYPHAN) exhibiting 14.1 mlO2/min and 13.2 mlCO2/min, respectively, at a maximum blood flow rate (Qmax = 200 ml/min). Silicone hollow sphere fibers show a promising competency to MHFs. They also show an evident dominancy over the conventional silicone fibers, evaluated by the control module, which emphasizes the advantage of this design.

  7. A theoretical model for evaluation of the design of a hollow-fiber membrane oxygenator.

    Science.gov (United States)

    Tabesh, Hadi; Amoabediny, Ghassem; Poorkhalil, Ali; Khachab, Ali; Kashefi, Ali; Mottaghy, Khosrow

    2012-12-01

    Geometric data are fundamental to the design of a contactor. The efficiency of a membrane contactor is mainly defined by its mass-transfer coefficient. However, design modifications also have significant effects on the performance of membrane contactors. In a hollow-fiber membrane oxygenator (HFMO), properties such as priming volume and effective membrane surface area (referred to as design specifications) can be determined. In this study, an extensive theoretical model for calculation of geometric data and configuration properties, and, consequently, optimization of the design of an HFMO, is presented. Calculations were performed for Oxyphan(®) hollow-fiber micro-porous membranes, which are frequently used in current HFMOs because of their high gas exchange performance. The results reveal how to regulate both the transverse and longitudinal pitches of fiber bundles to obtain a lower rand width and a greater number of windings. Such modifications assist optimization of module design and, consequently, substantially increase the efficiency of an HFMO. On the basis of these considerations, three values, called efficiency factors, are proposed for evaluation of the design specifications of an HFMO with regard with its performance characteristics (i.e. oxygen-transfer rate and blood pressure drop). Moreover, the performance characteristics of six different commercial HFMOs were measured experimentally, in vitro, under the same standard conditions. Comparison of calculated efficiency factors reveals Quadrox(®) is the oxygenator with the most efficient design with regard with its performance among the oxygenators tested.

  8. A new spinning technique for hollow fiber ultrafiltration membranes

    NARCIS (Netherlands)

    Wienk, I.M.; Wienk, I.M.; Teunis, Hermannus A.; van den Boomgaard, Anthonie; Smolders, C.A.; Smolders, C.A.

    1993-01-01

    A new spinning technique for hollow fiber membranes with a densified outer toplayer has been developed in our laboratory. This technique makes use of a new type of spinneret having three concentric orifices. Apart from polymer solution and bore liquid as applied in classical spinnerets a third liqui

  9. Failure Mechanisms of Hollow Fiber Supported Ionic Liquid Membranes.

    Science.gov (United States)

    Zeh, Matthew; Wickramanayake, Shan; Hopkinson, David

    2016-03-23

    Hollow fiber supported ionic liquid membranes (SILMs) were tested using the bubble point method to investigate potential failure modes, including the maximum transmembrane pressure before loss of the ionic liquid from the support. Porous hollow fiber supports were fabricated with different pore morphologies using Matrimid(®) and Torlon(®) as the polymeric material and 1-hexyl-3-methylimidalzolium bis(trifluoromethylsulfonyl)imide ([C₆mim][Tf₂N]) as the ionic liquid (IL) component. Hollow fiber SILMs were tested for their maximum pressure before failure, with pressure applied either from the bore side or shell side. It was found that the membranes exhibited one or more of three different modes of failure when pressurized: liquid loss (occurring at the bubble point), rupture, and collapse.

  10. Optical fiber modulator derivates from hollow optical fiber with suspended core.

    Science.gov (United States)

    Yang, Xinghua; Liu, Yanxin; Tian, Fengjun; Yuan, Libo; Liu, Zhihai; Luo, Shenzi; Zhao, Enming

    2012-06-01

    A fiber optic integrated modulation-depth-tunable modulator based on a type of hollow optical fiber with suspended core is proposed and investigated. We synthesized magnetic fluid containing superparamagnetic Fe(3)O(4) nanoparticles and encapsulated it in the hollow optical fiber as the cladding layer of the suspended core by fusing the hollow optical fiber with the multimode optical fibers. The light with a wavelength of 632.8 nm is coupled in and out of the modulating element by a tapering technique. Experimental results show that the light attenuation in the system can be greatly influenced by only 2.0×10(-2) μL of the magnetic fluid under different magnetic field strengths. The saturated modulation depth is 43% when the magnetic field strength is 489 Oe. The response time of the system is fiber modulators, including other integrated electro-optic devices, such as optical switch, optical fiber filter, and magnetic sensors utilizing the special structure of this hollow optical fiber with suspended core and superparamagnetic magnetic fluid.

  11. Clarification of Orange Press Liquors by PVDF Hollow Fiber Membranes

    Directory of Open Access Journals (Sweden)

    Silvia Simone

    2016-01-01

    Full Text Available Press liquors are typical by-products of the citrus juice processing characterized by a high content of organic compounds and associated problems of environmental impact, which imply high treatment costs. However, these wastes contain a great number of health promoting substances, including fibers, carotenoids and phenolic compounds (mainly flavonoids, whose recovery against waste-destruction technologies is very attractive for new business opportunities. In this work, the clarification of orange press liquor by using microfiltration (MF membranes is studied as a preliminary step to obtain a permeate stream enriched in antioxidant compounds which can be further processed to produce extracts of nutraceutical and/or pharmaceutical interest. MF poly(vinylidene fluoride (PVDF hollow fibers were prepared by the dry/wet spinning technique. A series of fibers was produced from the same polymeric dope, in order to investigate the effect of selected spinning parameters, i.e., bore fluid composition and flowrate, on their properties. The morphology of the produced fibers was analyzed by Scanning Electron Microscopy (SEM. Fibers were further characterized for their mechanical properties, porosity, bubble point, pore size distribution and pure water permeability (PWP. Some of the produced fibers exhibited high permeability (pure water permeability ~530 L/m2·h·bar, coupled to good mechanical resistance and pore size in the range of MF membranes. These fibers were selected and used for the clarification of press liquor from orange peel processing. In optimized operating conditions, the selected fibers produced steady-state fluxes of about 41 L/m2·h with rejections towards polyphenols and total antioxidant activity of 4.1% and 1.4%, respectively.

  12. Modulation of Tenoxicam release from hydrophilic matrix: modulator membrane versus rate-controlling membrane.

    Science.gov (United States)

    El-Nabarawi, Mohamed Ahmed

    2005-09-01

    This paper describes the preparation of two layered device comprising of tenoxicam containing layer and a drug free membrane layer based on Geomatrix Technology. Our device based on bilaminated films which produced by a casting/solvent evaporation technique. The drug-hydroxypropyl methylcellulose (HPMC) layer was covered by drug free membrane layer composed of a mixture of different ratios of HPMC and ethyl cellulose (EC). The prepared devices were evaluated for thickness, weight, drug content uniformity, water absorption capacity and in-vitro drug release. The films were also evaluated for appearance, smoothness and transparency. The influence of drug free membrane layer composition and thickness on the drug release pattern was studied on 12 devices (D1 to D12). The results indicate that, the release of drug from HPMC matrixes without the drug free membrane layer was fast and follows diffusion controlled mechanism. The release of drug from the devices D1, D4, D9 and D12 follow the same mechanism, while the release of drug from other devices become linear with time (zero order) and extended for long time especially when thickness and the ratio of EC was increased in the drug free membrane layer. From this study it is concluded that, changing the geometry of drug layer by addition of drug free membrane layer and changing its composition and thickness plays an important role in determining whether the drug free membrane layer is rate-controlling or modulator membrane. Hence it can facilitate the development of different pharmaceutical products with different release pattern.

  13. High-brightness, fiber-coupled pump modules in fiber laser applications

    Science.gov (United States)

    Hemenway, Marty; Urbanek, Wolfram; Hoener, Kylan; Kennedy, Keith W.; Bao, Ling; Dawson, David; Cragerud, Emily S.; Balsley, David; Burkholder, Gary; Reynolds, Mitch; Price, Kirk; Haden, Jim; Kanskar, Manoj; Kliner, Dahv A.

    2014-03-01

    High-power, high-brightness, fiber-coupled pump modules enable high-performance industrial fiber lasers with simple system architectures, multi-kW output powers, excellent beam quality, unsurpassed reliability, and low initial and operating costs. We report commercially available (element™), single-emitter-based, 9xx nm pump sources with powers up to 130 W in a 105 μm fiber and 250 W in a 200 μm fiber. This combination of high power and high brightness translates into improved fiber laser performance, e.g., simultaneously achieving high nonlinear thresholds and excellent beam quality at kW power levels. Wavelength-stabilized, 976 nm versions of these pumps are available for applications requiring minimization of the gain-fiber length (e.g., generation of high-peak-power pulses). Recent prototypes have achieved output powers up to 300 W in a 200 μm fiber. Extensive environmental and life testing at both the chip and module level under accelerated and real-world operating conditions have demonstrated extremely high reliability, with innovative designs having eliminated package-induced-failure mechanisms. Finally, we report integrated Pump Modules that provide conveniently formatted for fiber-laser pumping or direct-diode applications; these 19" rack-mountable, 2U units combine the outputs of up to 14 elements™ using fused-fiber combiners, and they include high-efficiency diode drivers and safety sensors.

  14. The Membrane Modulates Internal Proton Transfer in Cytochrome c Oxidase

    DEFF Research Database (Denmark)

    Öjemyr, Linda Nasvik; Ballmoos, Christoph von; Faxén, Kristina

    2012-01-01

    The functionality of membrane proteins is often modulated by the surrounding membrane. Here, we investigated the effect of membrane reconstitution of purified cytochrome c oxidase (CytcO) on the kinetics and thermodynamics of internal electron and proton-transfer reactions during O-2 reduction...

  15. Fabrication of a Polyamide/Polysulfone Hollow Fiber Composite Membrane

    Institute of Scientific and Technical Information of China (English)

    ZHANG Yu-feng; LIANG Chang-liang; DU Qi-yun; XIAO Chang-fa; YU Hong-liang

    2005-01-01

    With microporous polysulfone hollow fiber as the substrate,a polypiperazine amide nanofiltration composite membrane was prepared by interfacial polymerization in trimesoyl hexane solution as oil phase and piperazine aqueous solution as water phase. The conditions of the preparation, such as concentrations of monomer solutions, reaction time and temperature, annealing treatment, etc., were investigated.The hollow fiber composite herewith obtained showed high performance with water fluxes over 40 L · m-2 · hr-1 and MgSO4 rejection of 93% under a pressure of 0. 40 MPa.

  16. Hydrodynamic effects of air sparging on hollow fiber membranes in a bubble column reactor.

    Science.gov (United States)

    Xia, Lijun; Law, Adrian Wing-Keung; Fane, Anthony G

    2013-07-01

    Air sparging is now a standard approach to reduce concentration polarization and fouling of membrane modules in membrane bioreactors (MBRs). The hydrodynamic shear stresses, bubble-induced turbulence and cross flows scour the membrane surfaces and help reduce the deposit of foulants onto the membrane surface. However, the detailed quantitative knowledge on the effect of air sparging remains lacking in the literature due to the complex hydrodynamics generated by the gas-liquid flows. To date, there is no valid model that describes the relationship between the membrane fouling performance and the flow hydrodynamics. The present study aims to examine the impact of hydrodynamics induced by air sparging on the membrane fouling mitigation in a quantitative manner. A modelled hollow fiber module was placed in a cylindrical bubble column reactor at different axial heights with the trans-membrane pressure (TMP) monitored under constant flux conditions. The configuration of bubble column without the membrane module immersed was identical to that studied by Gan et al. (2011) using Phase Doppler Anemometry (PDA), to ensure a good quantitative understanding of turbulent flow conditions along the column height. The experimental results showed that the meandering flow regime which exhibits high flow instability at the 0.3 m is more beneficial to fouling alleviation compared with the steady flow circulation regime at the 0.6 m. The filtration tests also confirmed the existence of an optimal superficial air velocity beyond which a further increase is of no significant benefit on the membrane fouling reduction. In addition, the alternate aeration provided by two air stones mounted at the opposite end of the diameter of the bubble column was also studied to investigate the associated flow dynamics and its influence on the membrane filtration performance. It was found that with a proper switching interval and membrane module orientation, the membrane fouling can be effectively

  17. Hydrogen purifier module with membrane support

    Science.gov (United States)

    A hydrogen purifier utilizing a hydrogen-permeable membrane to purify hydrogen from mixed gases containing hydrogen is disclosed. Improved mechanical support for the permeable membrane is described, enabling forward or reverse differential pressurization of the membrane, which further stabilizes the membrane from wrinkling upon hydrogen uptake.

    2012-07-24

    A hydrogen purifier utilizing a hydrogen-permeable membrane to purify hydrogen from mixed gases containing hydrogen is disclosed. Improved mechanical support for the permeable membrane is described, enabling forward or reverse differential pressurization of the membrane, which further stabilizes the membrane from wrinkling upon hydrogen uptake.

  18. A new coiled hollow-fiber module design for enhanced microfiltration performance in biotechnology

    Energy Technology Data Exchange (ETDEWEB)

    Luque, S.; Mallubhotla, H.; Gehlert, G.; Belfort, G. [Rensselaer Polytechnic Inst., New York (United States). Howard P. Isermann Dept. of Chemical Engineering; Kuriyel, R.; Dzengeleski, S.; Pearl, S. [Millipore Corp., Bedford, MA (United States). BioProcess Div.

    1999-11-05

    The microfiltration performance of a novel membrane module design with helically wound hollow fibers is compared with that obtained with a standard commercial-type crossflow module containing linear hollow fibers. Cell suspension (yeast, E. coli, and mammalian cell cultures) commonly clarified in the biotechnology industry are used for this comparison. The effect of variables such as transmembrane pressure, particle suspension concentration, and feed flow rate on membrane performance is evaluated. Normalized permeation fluxes versus flow rate or Dean number behave according to a heat transfer correlation obtained with centrifugal instabilities of the Taylor type. The microfiltration performance of this new module design, which uses secondary flows in helical tubes, is significantly better than an equivalent current commercial crossflow module when filtering suspensions relevant to the biotechnology industry. Flux and capacity improvements of up to 3.2-fold (constant transmembrane pressure operation) and 3.9-fold (constant flux operation), respectively, were obtained with the helical module over those for the linear module.

  19. Hollow fiber membrane lumen modified by polyzwitterionic grafting

    KAUST Repository

    Le, Ngoc Lieu

    2016-08-24

    In this study, we demonstrate an effective way to modify the lumen of polyetherimide hollow fibers by grafting zwitterionic poly(sulfobetaine) to increase the membrane resistance to fouling. Surface-selective grafting of the protective hydrogel layers has been achieved in a facile two-step process. The first step is the adsorption of a macromolecular redox co-initiator on the lumen-side surface of the membrane, which in the second step, after flushing the lumen of the membrane with a solution comprising monomers and a complementary redox initiator, triggers the in situ cross-linking copolymerization at room temperature. The success of grafting reaction has been verified by the surface elemental analyses using X-ray photoelectron spectroscopy (XPS) and the surface charge evaluation using zeta potential measurements. The hydrophilicity of the grafted porous substrate is improved as indicated by the change of contact angle value from 44° to 30°, due to the hydration layer on the surface produced by the zwitterionic poly(sulfobetaine). Compared to the pristine polyetherimide (PEI) substrate, the poly(sulfobetaine) grafted substrates exhibit high fouling resistance against bovine serum albumin (BSA) adsorption, E. coli attachment and cell growth on the surface. Fouling minimization in the lumen is important for the use of hollow fibers in different processes. For instance, it is needed to preserve power density of pressure-retarded osmosis (PRO). In high-pressure PRO tests, a control membrane based on PEI with an external polyamide selective layer was seriously fouled by BSA, leading to a high water flux drop of 37%. In comparison, the analogous membrane, whose lumen was modified with poly(sulfobetaine), not only had a less water flux decline but also had better flux recovery, up to 87% after cleaning and hydraulic pressure impulsion. Clearly, grafting PRO hollow fiber membranes with zwitterionic polymeric hydrogels as a protective layer potentially sustains PRO

  20. Interaction of Serum Proteins with Surface of Hemodialysis Fiber Membranes

    Science.gov (United States)

    Afrin, Rehana; Shirako, Yuji; Kishimoto, Kikuo; Ikai, Atsushi

    2012-08-01

    The poly(vinyl pyrrolidone)-covered hydrophilic surface of hollow-fiber membranes (fiber membrane, hereafter) for hemodialysis was mechanically probed using modified tips on an atomic force microscope (AFM) with covalent crosslinkers and several types of serum protein. The retraction part of many of the force extension (F-E) curves obtained with AFM tips coated with serum albumin had a long and smooth extension up to 200-300 nm indicating forced elongation of poly(vinyl pyrrolidone) chains. When fibrinogen-coated tips were used, long extension F-E curves up to 500 nm with multiple peaks were obtained in addition to smooth curves most likely reflecting the unfolding of fibrinogen molecules. The results indicated that individual polymer chains had a significant affinity toward serum proteins. The adhesion frequency of tips coated with serum proteins was lower on the poly(vinyl pyrrolidone) surface than on the uncoated hydrophobic polysulfone surface.

  1. Array of planar membrane modules for producing hydrogen

    Science.gov (United States)

    Vencill, Thomas R [Albuquerque, NM; Chellappa, Anand S [Albuquerque, NM; Rathod, Shailendra B [Hillsboro, OR

    2012-05-08

    A shared or common environment membrane reactor containing a plurality of planar membrane modules with top and bottom thin foil membranes supported by both an intermediary porous support plate and a central base which has both solid extended members and hollow regions or a hollow region whereby the two sides of the base are in fluid communication. The membrane reactor operates at elevate temperatures for generating hydrogen from hydrogen rich feed fuels.

  2. Counteracting ammonia inhibition in anaerobic digestion by removal with a hollow fiber membrane contactor.

    Science.gov (United States)

    Lauterböck, B; Ortner, M; Haider, R; Fuchs, W

    2012-10-01

    The aim of the current study was to investigate the feasibility of membrane contactors for continuous ammonia (NH₃-N) removal in an anaerobic digestion process and to counteract ammonia inhibition. Two laboratory anaerobic digesters were fed slaughterhouse wastes with ammonium (NH₄⁺) concentrations ranging from 6 to 7.4 g/L. One reactor was used as reference reactor without any ammonia removal. In the second reactor, a hollow fiber membrane contactor module was used for continuous ammonia removal. The hollow fiber membranes were directly submerged into the digestate of the anaerobic reactor. Sulfuric acid was circulated in the lumen as an adsorbent solution. Using this set up, the NH₄⁺-N concentration in the membrane reactor was significantly reduced. Moreover the extraction of ammonia lowered the pH by 0.2 units. In combination that led to a lowering of the free NH₃-N concentration by about 70%. Ammonia inhibition in the reference reactor was observed when the concentration exceeded 6 g/L NH₄⁺-N or 1-1.2 g/L NH₃-N. In contrast, in the membrane reactor the volatile fatty acid concentration, an indicator for process stability, was much lower and a higher gas yield and better degradation was observed. The chosen approach offers an appealing technology to remove ammonia directly from media having high concentrations of solids and it can help to improve process efficiency in anaerobic digestion of ammonia rich substrates.

  3. Outer-selective pressure-retarded osmosis hollow fiber membranes from vacuum-assisted interfacial polymerization for osmotic power generation

    KAUST Repository

    Sun, Shipeng

    2013-11-19

    In this paper, we report the technical breakthroughs to synthesize outer-selective thin-film composite (TFC) hollow fiber membranes, which is in an urgent need for osmotic power generation with the pressure-retarded osmosis (PRO) process. In the first step, a defect-free thin-film composite membrane module is achieved by vacuum-assisted interfacial polymerization. The PRO performance is further enhanced by optimizing the support in terms of pore size and mechanical strength and the TFC layer with polydopamine coating and molecular engineering of the interfacial polymerization solution. The newly developed membranes can stand over 20 bar with a peak power density of 7.63 W/m2, which is equivalent to 13.72 W/m2 of its inner-selective hollow fiber counterpart with the same module size, packing density, and fiber dimensions. The study may provide insightful guidelines for optimizing the interfacial polymerization procedures and scaling up of the outer-selective TFC hollow fiber membrane modules for PRO power generation. © 2013 American Chemical Society.

  4. Outer-selective pressure-retarded osmosis hollow fiber membranes from vacuum-assisted interfacial polymerization for osmotic power generation.

    Science.gov (United States)

    Sun, Shi-Peng; Chung, Tai-Shung

    2013-11-19

    In this paper, we report the technical breakthroughs to synthesize outer-selective thin-film composite (TFC) hollow fiber membranes, which is in an urgent need for osmotic power generation with the pressure-retarded osmosis (PRO) process. In the first step, a defect-free thin-film composite membrane module is achieved by vacuum-assisted interfacial polymerization. The PRO performance is further enhanced by optimizing the support in terms of pore size and mechanical strength and the TFC layer with polydopamine coating and molecular engineering of the interfacial polymerization solution. The newly developed membranes can stand over 20 bar with a peak power density of 7.63 W/m(2), which is equivalent to 13.72 W/m(2) of its inner-selective hollow fiber counterpart with the same module size, packing density, and fiber dimensions. The study may provide insightful guidelines for optimizing the interfacial polymerization procedures and scaling up of the outer-selective TFC hollow fiber membrane modules for PRO power generation.

  5. Electrospun fiber membranes enable proliferation of genetically modified cells

    Directory of Open Access Journals (Sweden)

    Borjigin M

    2013-02-01

    Full Text Available Mandula Borjigin*, Chris Eskridge*, Rohina Niamat, Bryan Strouse, Pawel Bialk, Eric B KmiecDepartment of Chemistry, Delaware State University, Dover, DE, USA *These authors contributed equally to this work Abstract: Polycaprolactone (PCL and its blended composites (chitosan, gelatin, and lecithin are well-established biomaterials that can enrich cell growth and enable tissue engineering. However, their application in the recovery and proliferation of genetically modified cells has not been studied. In the study reported here, we fabricated PCL-biomaterial blended fiber membranes, characterized them using physicochemical techniques, and used them as templates for the growth of genetically modified HCT116-19 colon cancer cells. Our data show that the blended polymers are highly miscible and form homogenous electrospun fiber membranes of uniform texture. The aligned PCL nanofibers support robust cell growth, yielding a 2.5-fold higher proliferation rate than cells plated on standard plastic plate surfaces. PCL-lecithin fiber membranes yielded a 2.7-fold higher rate of proliferation, while PCL-chitosan supported a more modest growth rate (1.5-fold higher. Surprisingly, PCL-gelatin did not enhance cell proliferation when compared to the rate of cell growth on plastic surfaces. Keywords: nanofibers, PCL-biomaterial blends, miscibility, gene editing, cell proliferation

  6. Castelnuovo-Mumford regularity of associated graded modules and fiber cones of filtered modules

    CERN Document Server

    Dung, Le Xuan

    2011-01-01

    We give bounds on the Castelnuovo-Mumford regularity of the associated graded module of an arbitrary good filtration and of its fiber cone. These bounds extend previous results of Rossi-Trung-Valla and Linh.

  7. Directly modulated cable television transport systems using negative dispersion fiber

    Science.gov (United States)

    Lu, Hai-Han; Liaw, Je-Wei; Lee, Yi-Shiuan; Tsai, Wan-Lin; Ji, Yu-Jie

    2005-03-01

    A directly modulated AM-VSB cable-television transport system using negative dispersion fiber (NDF) as the transmission medium is proposed and successfully demonstrated. Good performances of carrier-to-noise radio, composite second order, and composite triple beat were obtained over a 70-km NDF transport without optical amplification. The directly modulated laser has a positive chirp, while NDF has a negative dispersion property in the transmission fiber. This negative dispersion property compensates for the laser chirp and results in a system with better transmission performance.

  8. Analytical analysis of modulation instability in fiber optics

    Directory of Open Access Journals (Sweden)

    M. Saeed Aslam

    2012-06-01

    Full Text Available In this paper, an improved analysis for modulation instability, which results from interaction between optical wave and noise, is presented. It is shown that Nonlinear Schrodinger equation (NLSE, which governs this process, leads to the coupled wave equations that result to Riccati's differential equations. A completely analytical solution of Riccati's equation is obtained for small fiber length that results in efficient computation of the modulation instability effect.

  9. Effect of polymer concentration on the structure and performance of PEI hollow fiber membrane contactor for CO2 stripping.

    Science.gov (United States)

    Naim, R; Ismail, A F

    2013-04-15

    A series of polyetherimide (PEI) hollow fiber membranes with various polymer concentrations (13-16 wt.%) for CO2 stripping process in membrane contactor application was fabricated via wet phase inversion method. The PEI membranes were characterized in terms of liquid entry pressure, contact angle, gas permeation and morphology analysis. CO2 stripping performance was investigated via membrane contactor system in a stainless steel module with aqueous diethanolamine as liquid absorbent. The hollow fiber membranes showed decreasing patterns in gas permeation, contact angle, mean pore size and effective surface porosity with increasing polymer concentration. On the contrary, wetting pressure of PEI membranes has enhanced significantly with polymer concentration. Various polymer concentrations have different effects on the CO2 stripping flux in which membrane with 14 wt.% polymer concentration showed the highest stripping flux of 2.7 × 10(-2)mol/m(2)s. From the performance comparison with other commercial membrane, it is anticipated that the PEI membrane has a good prospect in CO2 stripping via membrane contactor.

  10. Ethylene glycol as bore fluid for hollow fiber membrane preparation

    KAUST Repository

    Le, Ngoc Lieu

    2017-03-31

    We proposed the use of ethylene glycol and its mixture with water as bore fluid for the preparation of poly(ether imide) (PEI) hollow fiber membranes and compared their performance and morphology with membranes obtained with conventional coagulants (water and its mixture with the solvent N-methylpyrrolidone (NMP)). Thermodynamics and kinetics of the systems were investigated. Water and 1:1 water:EG mixtures lead to fast precipitation rates. Slow precipitation is observed for both pure EG and 9:1 NMP:water mixture, but the reasons for that are different. While low osmotic driving force leads to slow NMP and water transport when NMP:water is used, the high EG viscosity is the reason for the slow phase separation when EG is the bore fluid. The NMP:water mixture produces fibers with mixed sponge-like and finger-like structure with large pores in the inner and outer layers; and hence leading to a high water permeance and a high MWCO suitable for separation of large-sized proteins. As compared to NMP:water, using EG as bore fluid provides fibers with a finger-like bilayered structure and sponge-like layers near the surfaces, and hence contributing to the higher water permeance. It also induces small pores for better protein rejection.

  11. Membranized semiconductor rib waveguides for acousto-optic modulation enhancement

    DEFF Research Database (Denmark)

    Barretto, Elaine Cristina Saraiva; Hvam, Jørn Märcher

    2010-01-01

    Membranized rib waveguides are proposed as an efficient way to increase acousto-optic modulation by up to four orders of magnitude compared to the traditional structures, opening up possibilities of constructing more compact and power-saving devices.......Membranized rib waveguides are proposed as an efficient way to increase acousto-optic modulation by up to four orders of magnitude compared to the traditional structures, opening up possibilities of constructing more compact and power-saving devices....

  12. Modulational instability of few cycle pulses in optical fibers

    CERN Document Server

    Sarma, Amarendra K

    2010-01-01

    We investigate the modulational instability of a mathematical model [based on the model proposed by T. Brabec and F. Krausz, Phys.Rev. Lett. 78, 3282(1997)] appropriate for few cycle optical pulses with pulse duration as short as one carrier oscillation cycle in the context of a standard silica fiber operating at the telecommunication wavelength 1550 nm.

  13. Bench Scale Thin Film Composite Hollow Fiber Membranes for Post-Combustion Carbon Dioxide Capture

    Energy Technology Data Exchange (ETDEWEB)

    Glaser, Paul [General Electric Global Research, Niskayuna, NY (United States); Bhandari, Dhaval [General Electric Global Research, Niskayuna, NY (United States); Narang, Kristi [General Electric Global Research, Niskayuna, NY (United States); McCloskey, Pat [General Electric Global Research, Niskayuna, NY (United States); Singh, Surinder [General Electric Global Research, Niskayuna, NY (United States); Ananthasayanam, Balajee [General Electric Global Research, Niskayuna, NY (United States); Howson, Paul [General Electric Global Research, Niskayuna, NY (United States); Lee, Julia [General Electric Global Research, Niskayuna, NY (United States); Wroczynski, Ron [General Electric Global Research, Niskayuna, NY (United States); Stewart, Frederick [Idaho National Lab. (INL), Idaho Falls, ID (United States); Orme, Christopher [Idaho National Lab. (INL), Idaho Falls, ID (United States); Klaehn, John [Idaho National Lab. (INL), Idaho Falls, ID (United States); McNally, Joshua [Idaho National Lab. (INL), Idaho Falls, ID (United States); Rownaghi, Ali [Georgia Inst. of Technology, Atlanta, GA (United States); Lu, Liu [Georgia Inst. of Technology, Atlanta, GA (United States); Koros, William [Georgia Inst. of Technology, Atlanta, GA (United States); Goizueta, Roberto [Georgia Inst. of Technology, Atlanta, GA (United States); Sethi, Vijay [Western Research Inst., Laramie, WY (United States)

    2015-04-01

    GE Global Research, Idaho National Laboratory (INL), Georgia Institute of Technology (Georgia Tech), and Western Research Institute (WRI) proposed to develop high performance thin film polymer composite hollow fiber membranes and advanced processes for economical post-combustion carbon dioxide (CO2) capture from pulverized coal flue gas at temperatures typical of existing flue gas cleanup processes. The project sought to develop and then optimize new gas separations membrane systems at the bench scale, including tuning the properties of a novel polyphosphazene polymer in a coating solution and fabricating highly engineered porous hollow fiber supports. The project also sought to define the processes needed to coat the fiber support to manufacture composite hollow fiber membranes with high performance, ultra-thin separation layers. Physical, chemical, and mechanical stability of the materials (individual and composite) towards coal flue gas components was considered via exposure and performance tests. Preliminary design, technoeconomic, and economic feasibility analyses were conducted to evaluate the overall performance and impact of the process on the cost of electricity (COE) for a coal-fired plant including capture technologies. At the onset of the project, Membranes based on coupling a novel selective material polyphosphazene with an engineered hollow fiber support was found to have the potential to capture greater than 90% of the CO2 in flue gas with less than 35% increase in COE, which would achieve the DOE-targeted performance criteria. While lab-scale results for the polyphosphazene materials were very promising, and the material was incorporated into hollow-fiber modules, difficulties were encountered relating to the performance of these membrane systems over time. Performance, as measured by both flux of and selectivity for CO2 over other flue gas constituents was found to deteriorate over time, suggesting a system that was

  14. Synthesis and Preparation of Polysulfone Hollow Fiber Chelating Membrane Modified with Thiourea

    Institute of Scientific and Technical Information of China (English)

    WANG Bing; HUANG Lei; XIAO Feng

    2006-01-01

    Several kinds of chloromethyl polysulfones (CMPF) with different chlorinity and reactive groups were synthesized by Friedel-crafts reaction, which could be utilized as reactively matrix membrane materials. The CMPF hollow matrix membranes were prepared with phase inversion by utilization of CMPF/additive/DMAC casting solution and CMPF as membrane materials. It was found that the effects of additive content, bore liquid and dry spinning distance on the structure of CMPF hollow fiber matrix membrane were different. A high qualified polysulfone hollow fiber chelating membrane modified with thiourea as chelating groups was prepared using CMPF as membrane matrix materials,through the reaction between thiourea and CMPF hollow fiber matrix membrane to afford the methyl iso-thiourium polysulfone. The experimental results showed that thermal drawing could increase the mechanical properties of matrix membrane, and the thermal treatment could increase the homogeneity and stability of the structure of polysulfone hollow fiber chelating membrane modified with thiourea.

  15. Surface modification of PVDF hollow fiber membrane and its application in membrane aerated biofilm reactor (MABR).

    Science.gov (United States)

    Hou, Feifei; Li, Baoan; Xing, Minghao; Wang, Qin; Hu, Liang; Wang, Shichang

    2013-07-01

    A novel composite hollow fiber membrane for membrane aerated biofilm rector (MABR) was prepared by coating L-3,4-dihydroxyphenylalanine (DOPA) on the surface of PVDF membrane. MABR process study was conducted to test the performances of the original and modified membranes for 166 days. The results indicate that coated membrane showed 2 times higher gas flux, lower water contact angle (declined from 86.5° to 52°), and significantly improved surface roughness. The modified membrane displayed an excellent MABR performance. Its COD, NH4(+)-N and TN removal efficiencies were kept above 90%, 98.8% and 84.2% during the first 4-month experiment. By tracking experiment at 0.01 MPa, to achieve COD removal efficiency of 85.9%, half an hour is required with the modified membrane, instead of 6h using the original one. Besides, faster NH4(+)-N and TN removal at 0.01 MPa were also achieved with DOPA composite membrane. Copyright © 2013 Elsevier Ltd. All rights reserved.

  16. Synthesis of ceramic hollow fiber supported zeolitic imidazolate framework-8 (ZIF-8) membranes with high hydrogen permeability

    KAUST Repository

    Pan, Yichang

    2012-12-01

    Purification and recovery of hydrogen from hydrocarbons in refinery streams in the petrochemical industry is an emerging research field in the study of membrane gas separation. Hollow fiber membrane modules can be easily implemented into separation processes at the industrial scale. In this report, hollow yttria-stabilized zirconia (YSZ) fiber-supported zeolitic imidazole framework-8 (ZIF-8) membranes were successfully prepared using a mild and environmentally friendly seeded growth method. Our single-component permeation studies demonstrated that the membrane had a very high hydrogen permeance (~15×10 -7mol/m 2sPa) and an ideal selectivity of H 2/C 3H 8 of more than 1000 at room temperature. This high membrane permeability and selectivity caused serious concentration polarization in the separation of H 2/C 3H 8 mixtures, which led to almost 50% drop in both the H 2 permeance and the separation factor. Enhanced mixing on the feed side could reduce the effect of the concentration polarization. Our experimental data also indicated that the membranes had excellent reproducibility and long-term stability, indicating that the hollow fiber-supported ZIF-8 membranes developed in this study have great potential in industry-scale separation of hydrogen. © 2012 Elsevier B.V.

  17. High-Order Modulation for Optical Fiber Transmission

    CERN Document Server

    Seimetz, Matthias

    2009-01-01

    Catering to the current interest in increasing the spectral efficiency of optical fiber networks by the deployment of high-order modulation formats, this monograph describes transmitters, receivers and performance of optical systems with high-order phase and quadrature amplitude modulation. In the first part of the book, the author discusses various transmitter implementation options as well as several receiver concepts based on direct and coherent detection, including designs of new structures. Hereby, both optical and electrical parts are considered, allowing the assessment of practicability and complexity. In the second part, a detailed characterization of optical fiber transmission systems is presented, regarding a wide range of modulation formats. It provides insight in the fundamental behavior of different formats with respect to relevant performance degradation effects and identifies the major trends in system performance.

  18. Recovery of Copper Ions from Wastewater by Hollow Fiber Supported Emulsion Liquid Membrane

    Institute of Scientific and Technical Information of China (English)

    郑辉东; 陈晶晶; 王碧玉; 赵素英

    2013-01-01

    Recovery of copper ions from wastewater using a hollow fiber supported emulsion liquid membrane (HFSELM) was studied with LIX984N as carrier, kerosene as diluents, and sulfuric acid solution as stripping phase. Effects of compositions of feed and emulsion liquid phase, flow rates on both sides of membrane, and hollow fiber module parameters were investigated. The stability of the emulsion liquid phase without surfactant and the effect of buffer in the feed phase on the extraction rate were also evaluated. It is found that the stability of the emulsion phase without surfactant is poor. Higher flow velocity gives shorter residence time for the emulsion liquid phase on the tube side, reducing the effect of particle coalescence on the separation process. The extraction rate increases with the increase of feed phase pH, carrier concentration, hydrogen ion concentration in the stripping phase, and ef-fective hollow fiber area. The phase ratio in the emulsion liquid phase has a negative effect on extraction rate. The flow rates on both sides have little influence on the extraction performance of the HFSELM, while buffer addition in the feed solution improves the extraction efficiency.

  19. Frequency modulation via the Doppler effect in optical fibers.

    Science.gov (United States)

    Oberson, P; Huttner, B; Gisin, N

    1999-04-01

    We present the principle of optical frequency modulation via the Doppler effect obtained by rapidly stretching an optical fiber and thus modifying the optical path of the light propagating in the fiber. This procedure creates a pure frequency shift, with no degradation of the spectrum. Moreover, the effect is wavelength independent and can therefore be applied to any type of light source. We show an experimental realization in which a frequency excursion of ~100 MHz was obtained with a bobbin vibrating at 180 Hz.

  20. Low Cost Fiber Optic Module Development Program.

    Science.gov (United States)

    1979-12-01

    159.04 G&A @28% 24.89 28.63 SUBTOTAL 163.19 187.67 PROFIT @12% 19.58 22.52 TOTAL $ 182.77 $ 210.19 2 manufacturing aids should be performed with the...Characteristics Parameter Test Condition Min.lTypical Max. Unit High-level input voltage, VIH --- 2.0 2.4 --- V Low-level input voltage, VIL --- 0.4 0.8 V...retaining plate, and ceramic substrate temperatures were measured with the module under different operating modes at 250C and 950C ambient temperature. A

  1. Development and characterization of microfiltration hollow-fiber modules for sterilization of fermentation media

    Directory of Open Access Journals (Sweden)

    L.F.F. Faria

    2002-04-01

    Full Text Available Sterilization of fermentation medium involving heat may result in undesirable chemical reactions that alter nutrient concentration and yield products, which interfere in the fermentation performance. Sterilization of heat-sensitive compounds usually involves separate sterilizations of carbon source and nutrient solution. Membrane separation processes are an alternative to thermal processes, as they have many advantages such as the possibility of continuous and modular operation and the use of moderate temperatures. In this context, the objective of this work was the preparation of hollow-fiber membranes and the design of modules suitable for continuous sterilization of fermentation medium. The membrane with the best performance had a maximum pore diameter of 0.2 mu m and a permeability of 42.9 L/m².bar.h for a glucose/peptone/yeast extract medium. A module with 0.26 m² of permeation area was built with these membranes. This module was able to provide a permeate flow rate of 2.2 L/h using a pressure difference of 0.2 bar. The collected permeate was completely sterile, thus confirming the efficiency of this process.

  2. Membrane potential hyperpolarization in Mammalian cardiac cells by synchronization modulation of Na/K pumps.

    Science.gov (United States)

    Chen, Wei; Dando, Robin

    2008-02-01

    In previously reported work, we developed a new technique, synchronization modulation, to electrically activate Na/K pump molecules. The fundamental mechanism involved in this technique is a dynamic entrainment procedure of the pump molecules, carried out in a stepwise pattern. The entrainment procedure consists of two steps: synchronization and modulation. We theoretically predicted that the pump functions can be activated exponentially as a function of the membrane potential. We have experimentally demonstrated synchronization of the Na/K pump molecules and acceleration of their pumping rates by many fold through use of voltage-clamp techniques, directly monitoring the pump currents. We further applied this technique to intact skeletal muscle fibers from amphibians and found significant effects on the membrane resting potential. Here, we extend our study to intact mammalian cardiomyocytes. We employed a noninvasive confocal microscopic fluorescent imaging technique to monitor electric field-induced changes in ionic concentration gradient and membrane resting potential. Our results further confirm that the well-designed synchronization modulation electric field can effectively accelerate the Na/K pumping rate, increasing the ionic concentration gradient across the cell membrane and hyperpolarizing the membrane resting potential.

  3. Effect of biogas sparging with different membrane modules on membrane fouling in anaerobic submerged membrane bioreactor (AnSMBR).

    Science.gov (United States)

    Aslan, Mustafa; Saatçi, Yusuf; Hanay, Özge; Hasar, Halil

    2014-03-01

    This study focused on the effect of biogas sparging and different membrane modules such as cylinder shaped, funnel-shaped, and U-shaped on the membrane fouling behavior in a lab-scale submerged anaerobic membrane bioreactor (AnSMBR) which was operated for over 60 days. In order to investigate the membrane fouling behavior, a series of analysis such as SMP, EPS, scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX), particle size distribution, and filtration resistances were performed. Although the rapid generation of cake layer took placed in case of the absence of biogas sparging, the membrane module design mostly influenced the membrane resistance when biogas sparging was applied. Total resistance was the highest for U-shaped module. The permeate fluxes with biogas sparging were higher about one half and two times than those without biogas sparging. Cylinder-shaped module had the lowest SMP and EPS concentrations followed by U-shaped and funnel-shaped modules under both cases with and without biogas sparging. The total resistances of all membrane modules without biogas sparging were found to be very high compared the pore blocking resistances (Rp).

  4. Preparation of Composite Charge-mosaic Hollow Fiber Membrane by Interfacial Polymerization

    Institute of Scientific and Technical Information of China (English)

    Hao Qin ZHANG; Jin Dun LIU

    2004-01-01

    The preparation of composite charge-mosaic membrane included spinning of hollow fiber as the supporting membrane, preparing a selective layer on the inside surface of the fiber by interfacial polymerization. The charge-mosaic membranes show a high salt permeability while retaining sucrose. The charge-mosaic membrane can be effectively used to separate multivalent salts with organic matter of molecular weight great than 300 g/mol in industry.

  5. Polyimide hollow fiber membranes for CO2 separation from wet gas mixtures

    Directory of Open Access Journals (Sweden)

    F. Falbo

    2014-12-01

    Full Text Available Matrimid®5218 hollow fiber membranes were prepared using the dry-wet spinning process. The transport properties were measured with pure gases (H2, CO2, N2, CH4 and O2 and with a mixture (30% CO2 and 70% N2 in dry and wet conditions at 25 ºC, 50 ºC, 60 ºC and 75 ºC and up to 600 kPa. Interesting values of single gas selectivity up to 60 ºC (between 31 and 28 for CO2/N2 and between 33 and 30 for CO2/CH4 in dry condition were obtained. The separation factor measured for the mixture was 20% lower compared to the single gas selectivity, in the whole temperature range analyzed. In saturation conditions the data showed that water influences the performance of the membranes, inducing a reduction of the permeance of all gases. Moreover, the presence of water caused a decrease of single gas selectivity and separation factor, although not so significant, highlighting the very high water resistance of hollow fiber membrane modules.

  6. Anionic phospholipids modulate peptide insertion into membranes.

    Science.gov (United States)

    Liu, L P; Deber, C M

    1997-05-06

    While the insertion of a hydrophobic peptide or membrane protein segment into the bilayer can be spontaneous and driven mainly by the hydrophobic effect, anionic lipids, which comprise ca. 20% of biological membranes, provide a source of electrostatic attractions for binding of proteins/peptides into membranes. To unravel the interplay of hydrophobicity and electrostatics in the binding of peptides into membranes, we designed peptides de novo which possess the typical sequence Lys-Lys-Ala-Ala-Ala-X-Ala-Ala-Ala-Ala-Ala-X-Ala-Ala-Trp-Ala-Ala-X-Ala-Al a-Ala-Lys-Lys-Lys-Lys-amide, where X residues correspond to "guest" residues which encompass a range of hydrophobicity (Leu, Ile, Gly, and Ser). Circular dichroism spectra demonstrated that peptides were partially (40-90%) random in aqueous buffer but were promoted to form 100% alpha-helical structures by anionic lipid micelles. In neutral lipid micelles, only the relatively hydrophobic peptides (X = L and I) spontaneously adopted the alpha-helical conformation, but when 25% of negatively charged lipids were mixed in to mimic the content of anionic lipids in biomembranes, the less hydrophobic (X = S and G) peptides then formed alpha-helical conformations. Consistent with these findings, fluorescence quenching by the aqueous-phase quencher iodide indicated that in anionic (dimyristoylphosphatidylglycerol) vesicles, the peptide Trp residue was buried in the lipid vesicle hydrophobic core, while in neutral (dimyristoylphosphatidylcholine) vesicles, only hydrophobic (X = L and I) peptides were shielded from the aqueous solution. Trp emission spectra of peptides in the presence of phospholipids doxyl-labeled at the 5-, 7-, 10-, 12-, and 16-fatty acid positions implied not only a transbilayer orientation for inserted peptides but also that mixed peptide populations (transbilayer + surface-associated) may arise. Overall results suggest that for hydrophobic peptides with segmental threshold hydrophobicity below that which

  7. Composite hollow fiber membranes for organic solvent-based liquid-liquid extraction

    NARCIS (Netherlands)

    He, T.; Bolhuis-Versteeg, Lydia A.M.; Mulder, M.H.V.; Wessling, Matthias

    2004-01-01

    Instability issues of liquid membranes extraction significantly limit its wide application in industry. We report research on the application of a new composite hollow fiber membrane to stabilizing liquid membrane extraction. These type of composite membranes have either a polysulfone (PSf) ultrafil

  8. Composite hollow fiber membranes for organic solvent-based liquid-liquid extraction

    NARCIS (Netherlands)

    He, T.; Versteeg, L.A.M.; Mulder, M.H.V.; Wessling, M.

    2004-01-01

    Instability issues of liquid membranes extraction significantly limit its wide application in industry. We report research on the application of a new composite hollow fiber membrane to stabilizing liquid membrane extraction. These type of composite membranes have either a polysulfone (PSf) ultrafil

  9. Modulational instability in dispersion-kicked optical fibers

    CERN Document Server

    Nodari, S Rota; Dujardin, G; Kudlinski, A; Mussot, A; Trillo, S; De Bièvre, S

    2015-01-01

    We study, both theoretically and experimentally, modulational instability in optical fibers that have a longitudinal evolution of their dispersion in the form of a Dirac delta comb. By means of Floquet theory, we obtain an exact expression for the position of the gain bands, and we provide simple analytical estimates of the gain and of the bandwidths of those sidebands. An experimental validation of those results has been realized in several microstructured fibers specifically manufactured for that purpose. The dispersion landscape of those fibers is a comb of Gaussian pulses having widths much shorter than the period, which therefore approximate the ideal Dirac comb. Experimental spontaneous MI spectra recorded under quasi continuous wave excitation are in good agreement with the theory and with numerical simulations based on the generalized nonlinear Schr\\"odinger equation.

  10. Analysis of flux reduction behaviors of PRO hollow fiber membranes: Experiments, mechanisms, and implications

    KAUST Repository

    Xiong, Jun Ying

    2016-01-15

    Pressure retarded osmosis (PRO) is a promising technology to harvest renewable osmotic energy using a semipermeable membrane. However, a significant flux reduction has been always observed that severely shrinks the harvestable power to a level only marginally higher or even lower than the economically feasible value. This work focuses on the elucidation of various underlying mechanisms responsible for the flux reduction. First, both inner-selective and outer-selective thin film composite (TFC) hollow fiber membranes are employed to examine how the fundamental internal factors (such as the surface salinity of the selective layer at the feed side (CF,m) and its components) interact with one another under the fixed bulk salinity gradient, resulting in various behaviours of external performance indexes such as water flux, reverse salt flux, and power density. Then, the research is extended to investigate the effects of the growing bulk feed salinity due to the accumulated reverse salt flux along PRO modules. Finally, the insights obtained from the prior two stationary conditions are combined with the advanced nucleation theory to elucidate the dynamic scaling process by visualizing how the multiple fundamental factors (such as local supersaturation, nucleation rate and nuclei size) evolve and interplay with one another in various membrane regimes during the whole scaling process. To our best knowledge, it is the first time that the advanced nucleation theory is applied to study the PRO scaling kinetics in order to provide subtle and clear pictures of the events occurring inside the membrane. This study may provide useful insights to design more suitable TFC hollow fiber membranes and to operate them with enhanced water flux so that the PRO process may become more promising in the near future.

  11. All-fiber optical modulator based on no-core fiber and magnetic fluid as cladding

    Science.gov (United States)

    Chen, Yao-Fei; Han, Qun; Liu, Tie-Gen

    2015-01-01

    An all-fiber optical modulator, which is composed of a piece of no-core fiber spliced between two sections of single-mode fibers and uses magnetic fluid (MF) as the cladding of the no-core fiber section, is proposed and investigated experimentally. Due to the tunable refractive index and absorption coefficient of MF, the output intensity can be modulated by controlling an applied magnetic field. The dependences of the modulator’s temporal response on the working wavelength, the magnetic field strength (H), and the MF’s concentration are investigated experimentally. The results are explained qualitatively by the dynamic response process of MF under the action of a magnetic field. The findings are helpful for optimizing this kind of modulator. Project supported by the Natural Science Foundation of Tianjin City, China (Grant No. 13JCYBJC16100), the National Natural Science Foundation of China (Grant No. 61107035), the National Key Scientific Instrument and Equipment Development Project of China (Grant No. 2013YQ03091502), and the National Basic Research Program of China (Grant Nos. 2010CB327802 and 2010CB327806).

  12. Enriched glucose and dextrin mannitol-based media modulates fibroblast behavior on bacterial cellulose membranes.

    Science.gov (United States)

    Stumpf, Taisa R; Pértile, Renata A N; Rambo, Carlos R; Porto, Luismar M

    2013-12-01

    Bacterial cellulose (BC) produced by Gluconacetobacter hansenii is a suitable biopolymer for biomedical applications. In order to modulate the properties of BC and expand its use as substrate for tissue engineering mainly in the form of biomembranes, glucose or dextrin were added into a BC fermentation mannitol-based medium (BCGl and BCDe, respectively) under static culture conditions. SEM images showed effects on fiber density and porosity on both sides of the BC membranes. Both enriched media decreased the BET surface area, water holding capacity, and rehydration rate. Fourier transform infrared (attenuated total reflectance mode) spectroscopy (FTIR-ATR) analysis revealed no change in the chemical structure of BC. L929 fibroblast cells were seeded on all BC-based membranes and evaluated in aspects of cell adhesion, proliferation and morphology. BCG1 membranes showed the highest biological performance and hold promise for the use in tissue engineering applications.

  13. Xanthophylls as modulators of membrane protein function.

    Science.gov (United States)

    Ruban, Alexander V; Johnson, Matthew P

    2010-12-01

    This review discusses the structural aspect of the role of photosynthetic antenna xanthophylls. It argues that xanthophyll hydrophobicity/polarity could explain the reason for xanthophyll variety and help to understand their recently emerging function--control of membrane organization and the work of membrane proteins. The structure of a xanthophyll molecule is discussed in relation to other amphiphilic compounds like lipids, detergents, etc. Xanthophyll composition of membrane proteins, the role of their variety in protein function are discussed using as an example for the major light harvesting antenna complex of photosystem II, LHCII, from higher plants. A new empirical parameter, hydrophobicity parameter (H-parameter), has been introduced as an effective measure of the hydrophobicity of the xanthophyll complement of LHCII from different xanthophyll biosynthesis mutants of Arabidopsis. Photosystem II quantum efficiency was found to correlate well with the H-parameter of LHCII xanthophylls. PSII down-regulation by non-photochemical chlorophyll fluorescence quenching, NPQ, had optimum corresponding to the wild-type xanthophyll composition, where lutein occupies intrinsic sites, L1 and L2. Xanthophyll polarity/hydrophobicity alteration by the activity of the xanthophyll cycle explains the allosteric character of NPQ regulation, memory of illumination history and the hysteretic nature of the relationship between the triggering factor, ΔpH, and the energy dissipation process. Copyright © 2010 Elsevier Inc. All rights reserved.

  14. Dynamics of Turing and Faraday instabilities in a longitudinally modulated fiber-ring cavity.

    Science.gov (United States)

    Copie, F; Conforti, M; Kudlinski, A; Trillo, S; Mussot, A

    2017-02-01

    We experimentally investigate the round-trip-to-round-trip dynamics of the modulation instability spectrum in a passive fiber-ring cavity presenting an inhomogeneous dispersion profile. By implementing a real-time spectroscopy technique, we are able to record successive single-shot spectra, which display the evolution of the system toward a stationary state. We find that the two instability regimes (Turing and Faraday) that compete in this kind of inhomogeneous cavity not only differ by their characteristic frequency but also by their dynamical behavior. The dynamic transition between those two regimes of instability is also presented.

  15. Hollow fiber membrane contactor as a gas–liquid model contactor

    NARCIS (Netherlands)

    Dindore, V.Y.; Brilman, D.W.F.; Versteeg, G.F.

    2005-01-01

    Microporous hollow fiber gas–liquid membrane contactors have a fixed and well-defined gas–liquid interfacial area. The liquid flow through the hollow fiber is laminar, thus the liquid side hydrodynamics are well known. This allows the accurate calculation of the fiber side physical mass transfer coe

  16. Hollow fiber membrane contactor as a gas-liquid model contactor

    NARCIS (Netherlands)

    Dindore, V. Y.; Brilman, D. W. F.; Versteeg, G. F.

    2005-01-01

    Microporous hollow fiber gas-liquid membrane contactors have a fixed and well-defined gas-liquid interfacial area. The liquid flow through the hollow fiber is laminar, thus the liquid side hydrodynamics are well known. This allows the accurate calculation of the fiber side physical mass transfer coe

  17. Hollow fiber membrane based H-2 diffusion for efficient in situ biogas upgrading in an anaerobic reactor

    DEFF Research Database (Denmark)

    Luo, Gang; Angelidaki, Irini

    2013-01-01

    Bubbleless gas transfer through a hollow fiber membrane (HFM) module was used to supply H2 to an anaerobic reactor for in situ biogas upgrading, and it creates a novel system that could achieve a CH4 content higher than 90 % in the biogas. The increase of CH4 content and pH, and the decrease of b...... also demonstrated that the biofilm formed on the membrane only contributed 22-36 % to the H2 consumption, while most of the H2 was consumed by the microorganisms in the liquid phase....

  18. Simulation of propagation in a bundle of skeletal muscle fibers: Modulation effects of passive fibers

    DEFF Research Database (Denmark)

    Henneberg, Kaj-åge; F.A., Roberge

    1997-01-01

    source current (I-ma) enters the passive tissue as a radial load current (I-ep) while the rest flows longitudinally in the cleft between the active and adjacent passive fibers. The conduction velocity of 1.32 m/s was about 30% lower than on an isolated fiber in a Ringer bath, in close agreement...... rate of rise of the action potential upstroke (V-max) from 512 to 503 V/s. Increasing the phase angle of the passive fiber membrane impedence (Z(m)) increases the phase delay between I-ma and I-ep, thereby increasing phi(epp) which in turn slows down propagation and increases V-max....

  19. Studies on poly (vinyl chloride/silica dioxide composite hollow fiber membrane

    Directory of Open Access Journals (Sweden)

    Mei Shuo

    2016-01-01

    Full Text Available Poly (vinyl chloride/silica dioxide composite hollow fiber membranes were prepared by using the method of immersion-precipitation process. The influences of stretching ratio on the formation of the interfacial microporous of poly (vinyl chloride/silica dioxide composite hollow fiber membranes were specifically investigated by scanning electron microscope, dynamic mechanical analysis, and finite element method. Results show that with the stretching ratio increasing, numerous IFM appear on the surface of membranes. Finite element method actually reflects the dynamic change of microporous structure of poly (vinyl chloride/silica dioxide composite hollow fiber membranes.

  20. MWIR optical modulation using structured silicon membranes

    Science.gov (United States)

    Zakar, A.; Park, S. J.; Zerova, V.; Kaplan, A.; Canham, Leigh T.; Lewis, K. L.; Burgess, C. D.

    2016-10-01

    We have used near IR pump - Mid IR probe techniques to compare the feasibility and potential of using free standing nano-porous and micro-porous silicon (ordered hole arrays) as optically controlled modulators operating in the Mid-Wave Infrared (MWIR) covering the range from 3.3-5 μm. We employed 800 nm pumping pulses with the duration of 60 fs to reduce 4 μm light transmission modulation to about 25% and 45% for both silicon structures, respectively, at excitation powers of 50mW (4 mJ=cm2). However, at 5 μm both structures shown similar contrast of about 60%. The time resolved measurements revealed a fast sub-picosecond rise time for both structures suggesting that the optically generated carriers are a dominant mechanism for the modulation. However, the measurements demonstrated a significant difference in the relaxation dynamics. The nanoporous silicon demonstrated recovery as fast as a few tens of picoseconds and a possibility to effectively work in the GHz regime, while hole arrays shown almost three orders of magnitude slower response making it suitable for the MHz regime.

  1. Higher-order modulation instability in nonlinear fiber optics.

    Science.gov (United States)

    Erkintalo, Miro; Hammani, Kamal; Kibler, Bertrand; Finot, Christophe; Akhmediev, Nail; Dudley, John M; Genty, Goëry

    2011-12-16

    We report theoretical, numerical, and experimental studies of higher-order modulation instability in the focusing nonlinear Schrödinger equation. This higher-order instability arises from the nonlinear superposition of elementary instabilities, associated with initial single breather evolution followed by a regime of complex, yet deterministic, pulse splitting. We analytically describe the process using the Darboux transformation and compare with experiments in optical fiber. We show how a suitably low frequency modulation on a continuous wave field induces higher-order modulation instability splitting with the pulse characteristics at different phases of evolution related by a simple scaling relationship. We anticipate that similar processes are likely to be observed in many other systems including plasmas, Bose-Einstein condensates, and deep water waves.

  2. A plasma membrane association module in yeast amino acid transporters

    NARCIS (Netherlands)

    Popov-Čeleketić, Dušan; Bianchi, Frans; Ruiz, Stephanie J; Meutiawati, Febrina; Poolman, Bert

    2016-01-01

    Amino acid permeases (AAPs) in the plasma membrane (PM) of Saccharomyces cerevisiae are responsible for the uptake of amino acids and involved in regulation of their cellular levels. Here, we report on a strong and complex module for PM association found in the C-terminal tail of AAPs. Using in sili

  3. A plasma membrane association module in yeast amino acid transporters

    NARCIS (Netherlands)

    Popov-Čeleketić, Dušan; Bianchi, Frans; Ruiz, Stephanie J; Meutiawati, Febrina; Poolman, Bert

    2016-01-01

    Amino acid permeases (AAPs) in the plasma membrane (PM) of Saccharomyces cerevisiae are responsible for the uptake of amino acids and involved in regulation of their cellular levels. Here, we report on a strong and complex module for PM association found in the C-terminal tail of AAPs. Using in

  4. Highly Sensitive Temperature Sensors Based on Fiber-Optic PWM and Capacitance Variation Using Thermochromic Sensing Membrane.

    Science.gov (United States)

    Khan, Md Rajibur Rahaman; Kang, Shin-Won

    2016-07-09

    In this paper, we propose a temperature/thermal sensor that contains a Rhodamine-B sensing membrane. We applied two different sensing methods, namely, fiber-optic pulse width modulation (PWM) and an interdigitated capacitor (IDC)-based temperature sensor to measure the temperature from 5 °C to 100 °C. To the best of our knowledge, the fiber-optic PWM-based temperature sensor is reported for the first time in this study. The proposed fiber-optic PWM temperature sensor has good sensing ability; its sensitivity is ~3.733 mV/°C. The designed temperature-sensing system offers stable sensing responses over a wide dynamic range, good reproducibility properties with a relative standard deviation (RSD) of ~0.021, and the capacity for a linear sensing response with a correlation coefficient of R² ≈ 0.992 over a wide sensing range. In our study, we also developed an IDC temperature sensor that is based on the capacitance variation principle as the IDC sensing element is heated. We compared the performance of the proposed temperature-sensing systems with different fiber-optic temperature sensors (which are based on the fiber-optic wavelength shift method, the long grating fiber-optic Sagnac loop, and probe type fiber-optics) in terms of sensitivity, dynamic range, and linearity. We observed that the proposed sensing systems have better sensing performance than the above-mentioned sensing system.

  5. Fabrication of Polybenzimidazole/Palladium Nanoparticles Hollow Fiber Membranes for Hydrogen Purification

    KAUST Repository

    Villalobos, Luis Francisco

    2017-09-13

    A novel scheme to fabricate polybenzimidazole (PBI) hollow fiber membranes with a thin skin loaded with fully dispersed palladium nanoparticles is proposed for the first time. Palladium is added to the membrane during the spinning process in the form of ions that coordinate to the imidazole groups of the polymer. This is attractive for membrane production because agglomeration of nanoparticles is minimized and the high-cost metal is incorporated in only the selective layer—where it is required. Pd-containing membranes achieve three orders of magnitude higher H2 permeances and a twofold improvement in H2/CO2 selectivity compared to pure PBI hollow fiber membranes.

  6. Transport of yttrium metal ions through fibers supported liquid membrane solvent extraction

    Institute of Scientific and Technical Information of China (English)

    A.G.Gaikwad; A.M.Rajput

    2010-01-01

    A novel idea of transport of yttrium(Ⅲ) metal ions through fibers supported liquid membrane in two stage processes namely source to membrane and membrane to receiving phase has been proposed.The fibers supported liquid membrane was impregnated with different concentrations carrier.The experimental variables explored were concentration of yttrium(Ⅲ) ions,pH of source phase,PC-88A concentration in membrane phase,acid concentration in receiving phase and stirring speed.The pre-concentration of yttrium(Ⅲ) ions ...

  7. Foulant analysis of hollow fine fiber (HFF) membranes in Red Sea SWRO plants using membrane punch autopsy (MPA)

    KAUST Repository

    Green, Troy N.

    2017-06-12

    Membrane punch autopsy (MPA) is a procedure for quantitative foulant analysis of hollow fine fiber (HFF) permeators. In the past, quantitative autopsies of membranes were restricted to spiral wound. This procedure was developed at SWCC laboratories and tested on permeators of two commercial Red Sea reverse osmosis plants. For membrane autopsies, stainless steel hollow bore picks were penetrated to membrane cores and fibers extracted for foulant analysis. Quantitative analysis of extracted materials contained inorganic and organic foulants including bacteria. Fourier transform infrared spectroscopy analysis confirmed the presence of organic fouling functional groups and scanning electron microscopy with energy dispersive X-ray spectroscopy in the presence of diatoms and silica most likely not from particulate sand. API analysis revealed the presence of Shewanella and two Vibrio microbial species confirmed by 16S rDNA sequence library. It was observed that fouling content of HFF cellulose triacetate (CTA) membranes were more than 800 times than polyamide spiral wound membranes.

  8. Composite materials of glycerol polyesters and piassava fibers as conducting membranes for PEMFC

    Energy Technology Data Exchange (ETDEWEB)

    Alves, J.L.; Jose, N.M.; Boaventura, J.S. [Federal Univ. of Bahia, Salvador (Brazil). Dept. of Physical Chemistry

    2009-07-01

    This paper described a method of using piassava fibers to produce polymers for proton exchange membrane fuel cells (PEMFCs). The composite membranes were produced using polyesters obtained from adipic and phthalic acid reactions with glycerol and piassava fibers treated with phosphoric acid. The piassava and polyesters were prepared as a mixture in liquid nitrogen. The mixture was then hot-pressed in order to produce composites with a fiber mass of 3, 5, 10 and 15 per cent. The fibers were then analyzed using scanning electron microscopy (SEM) and thermogravimetric analysis (TGA). The analyses demonstrated that the piassava fibers gave mechanical strength to the composite and improved proton conductor properties. A high fiber dispersion was observed in the matrix. Electric conductivity tests revealed that the membrane had a conductivity of approximately 0.5 Siemens per cm of acidic media.

  9. Hollow-fiber blood-dialysis membranes: superoxide generation, permeation, and dismutation measured by chemiluminescence.

    Science.gov (United States)

    Yamamoto, Ken-ichiro; Kobayashi, Kazuyoshi; Endo, Kosuke; Miyasaka, Takehiro; Mochizuki, Seiichi; Kohori, Fukashi; Sakai, Kiyotaka

    2005-01-01

    The interaction of blood with a material surface results in activation of the body's humoral immune system and the generation of reactive oxygen species (ROS). It has recently become clear that ROS are central to the pathology of many diseases. In this study, we evaluated the superoxide generation, permeation, and dismutation in hollow-fiber dialysis membranes by using 2-methyl-6-p-methoxyphenylethynyl-imidazopyrazinone (MPEC) as a superoxide-reactive chemiluminescence producer and an optical fiber probe to detect the resulting chemiluminescence in the hollow fiber lumen. We measured the superoxide generated when bovine blood leukocytes were brought into contact with dialysis membranes. Superoxide permeation was determined by measuring MPEC chemiluminescence in the hollow fiber lumen using an optical fiber probe. Additionally, superoxide dismutation was evaluated by examining the difference in superoxide permeability for membranes with and without vitamin E coating. Superoxide generation varies for different membrane materials, depending on the membrane's biocompatibility. Superoxide permeability depends on the diffusive permeability of membranes. No marked decrease in superoxide permeability was observed among membrane materials. The superoxide permeability of vitamin E-coated membrane was smaller than that of uncoated membrane. The antioxidant property of vitamin E-coated membranes is hence effective in causing superoxide dismutation.

  10. A comparative study of the membrane structure in different types of muscle fibers in the frog.

    Science.gov (United States)

    Verma, V

    1984-09-01

    The muscle membrane of slow and fast fibers in cruralis and iliofibularis muscles and of intermediate fibers in submaxillaris muscle of the frog is studied in freeze-fracture replicas. A comparison of membrane folds, number, size and distribution of caveolae and of intramembrane particles (IMP) is given. In slow muscle fibers, the membrane folds are systematically present at the level of the I zone with a transversal continuity, whereas in fast and intermediate types the membrane folds are small and are randomly distributed. In slow muscle the caveolae are more numerous at the I zone than in the part corresponding to the center of the sarcomere. In fast muscle, small groups of caveolae form linear patterns, and in intermediate fibers the distribution is random. The number of caveolae in slow muscle fibers is two times more than in fast and intermediate fibers. The mean area of caveolae opening is largest in fast and smallest in slow muscle fibers. The number of IMP is significantly different in the three types of fibers, being highest in slow and lowest in intermediate fibers. The different pattern of folds in slow fibers may correspond to the different contractile properties of this fiber type. The presence of double the number of caveolae in slow fibers correlated to the less elaborate T system in this fiber type shows the possibility that slow fibers may be the result of an arrest during development for the performance of a different function. The difference in IMP density in the three muscle fiber types may be interpreted as the difference in their electrical properties.

  11. Hollow fiber liquid-supported membrane technology for enantioseparation of racemic salbutamol by combinatorial chiral selectors

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    Enantioseparation of salbutamol solute was carried out in liquid-supported membrane by using a polyvinylidene fluoride hollow-fiber module. The enantioselective transport of solute was facilitated by combinatorial chiral selectors, which were dissolved in toluene organic solvent. The effects of molar concentration ratios of salbutamol to combinatorial chiral selectors, and the pH value of buffer solution on enantioseparation were investigated. The results show that when the molar concentration ratio is 2: 1:1, the maximum separation factor and enantiomer excess are 1.49 and 19.74%, respectively, and the R-enantiomer flux is more than S-enantiomer; the pH value of buffer solution influences the performances of enantioseparartion obviously, and the appropriate range of pH value is7.0-7.2.

  12. A geometrical view of modulation instability in optical fibers

    CERN Document Server

    Hernandez, S M; Bonetti, J; Sánchez, A D; Grosz, D F

    2016-01-01

    We derive a simple geometrical description of the gain of modulation instability (MI) in optical fibers based on a model which takes into account all relevant linear and nonlinear effects. This novel approach allows us to relate the shape of the MI gain to any arbitrary dispersion profile of the waveguide in a simple manner. It also yields a straightforward explanation of the non-trivial dependence of the cutoff power on high-order dispersion. Further, we show that the power level maximizing the MI gain, a unique feature enabled by self-steepening, is greatly influenced by high-order dispersion and can be explicitly obtained. Finally, our model provides a powerful tool to synthesize a desired MI gain profile by appropriate waveguide design, with the potential application to a vast number of parametric-amplification and supercontinuum-generation devices whose functioning relies upon modulation instability.

  13. Multiplexing technique using amplitude-modulated chirped fiber Bragg gratings

    Science.gov (United States)

    Wong, Allan C. L.; Childs, Paul A.; Peng, Gang-Ding

    2007-07-01

    We propose a new multiplexing technique using amplitude-modulated chirped fiber Bragg gratings that have an identical center Bragg wavelength. Each grating is inscribed with a unique amplitude modulation that allows them to be multiplexed with complete overlapping within a certain bandwidth. To demodulate the multiplexed signal, the discrete wavelet transform is employed. Concurrently, a wavelet denoising technique is used to reduce the noise. This proposed multiplexing technique has been verified through strain measurements. Experimental results showed that for strains applied up to 1250 μɛ the absolute error and cross-talk are within ±20 μɛ and 16 μɛ, respectively. A strain resolution of 4 μɛ is obtained.

  14. Modulation of TRESK background K+ channel by membrane stretch.

    Directory of Open Access Journals (Sweden)

    Gerard Callejo

    Full Text Available The two-pore domain K(+ channel TRESK is expressed in dorsal root ganglion and trigeminal sensory neurons where it is a major contributor to background K(+ current. TRESK acts as a break to prevent excessive sensory neuron activation and decreases in its expression or function have been involved in neuronal hyperexcitability after injury/inflammation, migraine or altered sensory perception (tingling, cooling and pungent burning sensations. All these effects have implicated this channel in nociception and mechanotransduction. To determine the role of TRESK in sensory transduction, we studied its sensitivity to changes in membrane tension (stretch in heterologous systems, F-11 cells and trigeminal neurons. Laminar shear stress increased TRESK currents by 22-30%. An increase in membrane tension induced by cell swelling (hypotonic medium produced a reversible elevation of TRESK currents (39.9%. In contrast, cell shrinkage (hypertonic solution produced the opposite effect. Membrane crenators or cup-formers produced equivalent effects. In trigeminal sensory neurons, TRESK channels were mechanically stimulated by negative pressure, which led to a 1.51-fold increase in channel open probability. TRESK-like currents in trigeminal neurons were additively inhibited by arachidonic acid, acidic pH and hypertonic stimulation, conditions usually found after tissue inflammation. Our results show that TRESK is modulated by changes in cell membrane tension and/or cell volume. Several key players released during inflammation or tissue injury could modulate sensory neuron activation through small changes in membrane tension.

  15. Surface monofunctionalized polymethyl pentene hollow fiber membranes by plasma treatment and hemocompatibility modification for membrane oxygenators

    Science.gov (United States)

    Huang, Xin; Wang, Weiping; Zheng, Zhi; Fan, Wenling; Mao, Chun; Shi, Jialiang; Li, Lei

    2016-01-01

    The hemocompatibility of polymethyl pentene (PMP) hollow fiber membranes (HFMs) was improved through surface modification for membrane oxygenator applications. The modification was performed stepwise with the following: (1) oxygen plasma treatment, (2) functionalization of monosort hydroxyl groups through NaBH4 reduction, and (3) grafting 2-methacryloyloxyethyl phosphorylcholine (MPC) or heparin. SEM, ATR-FTIR, and XPS analyses were conducted to confirm successful grafting during the modification. The hemocompatibility of PMP HFMs was analyzed and compared through protein adsorption, platelet adhesion, and coagulation tests. Pure CO2 and O2 permeation rates, as well as in vitro gas exchange rates, were determined to evaluate the mass transfer properties of PMP HFMs. SEM results showed that different nanofibril topographies were introduced on the HFM surface. ATR-FTIR and XPS spectra indicated the presence of functionalization of monosort hydroxyl group and the grafting of MPC and heparin. Hemocompatibility evaluation results showed that the modified PMP HFMs presented optimal hemocompatibility compared with pristine HFMs. Gas permeation results revealed that gas permeation flux increased in the modified HFMs because of dense surface etching during the plasma treatment. The results of in vitro gas exchange rates showed that all modified PMP HFMs presented decreased gas exchange rates because of potential surface fluid wetting. The proposed strategy exhibits a potential for fabricating membrane oxygenators for biomedical applications to prevent coagulation formation and alter plasma-induced surface topology and composition.

  16. Modulation Instabilities in Birefringent Two-Core Optical Fibers

    CERN Document Server

    Li, J H; Malomed, B A; Chow, K W

    2012-01-01

    Previous studies of the modulation instability (MI) of continuous waves (CWs) in a two-core fiber (TCF) did not consider effects caused by co-propagation of the two polarized modes in a TCF that possesses birefringence, such as cross-phase modulation (XPM), polarization-mode dispersion (PMD), and polarization-dependent coupling (PDC) between the cores. This paper reports an analysis of these effects on the MI by considering a linear-birefringence TCF and a circular-birefringence TCF, which feature different XPM coefficients. The analysis focuses on the MI of the asymmetric CW states in the TCFs, which have no counterparts in single-core fibers. We find that, the asymmetric CW state exists when its total power exceeds a threshold (minimum) value, which is sensitive to the value of the XPM coefficient. We consider, in particular, a class of asymmetric CW states that admit analytical solutions. In the anomalous dispersion regime, without taking the PMD and PDC into account, the MI gain spectra of the birefringen...

  17. FOST 2 Upgrade with Hollow-Fiber CTA FO Module and Generation of Osmotic Agent for Microorganism Growth Studies

    Science.gov (United States)

    Parodi, Jurek; Mangado, Jaione Romero; Stefanson, Ofir; Flynn, Michael; Shaw, Hali; Beeler, David

    2016-01-01

    FOST 2 is an integrated membrane system that incorporates a forward osmosis subsystem and a reverse osmosis subsystem working in series. It has been designed as a post treatment system to process the effluent from the Membrane Aerated Biological Reactor developed at NASA Johnson Space Center and Texas Tech University. Its function is to remove dissolved solids residual such as ammonia and suspended solids, as well as to provide a physical barrier to microbial and viral contamination. A tubular CTA membrane module from HTI and a flat-sheet lipid-base membrane module from Porifera were integrated and tested on FOST 2 in the past, using both a bioreactor's effluent and greywater as the feed solution. This paper documents the performance of FOST 2 after its upgrade with a hollow-fiber CTA membrane module from Toyobo, treating real black-water to generate the osmotic agent solution necessary to conduct growth studies of genetically engineered microorganism for the Synthetic Biological Membrane project.

  18. Free-standing membrane polymer laser on the end of an optical fiber

    Energy Technology Data Exchange (ETDEWEB)

    Zhai, Tianrui, E-mail: trzhai@bjut.edu.cn, E-mail: zhangxinping@bjut.edu.cn; Li, Songtao; Hu, Yujie; Wang, Yimeng; Wang, Li; Zhang, Xinping, E-mail: trzhai@bjut.edu.cn, E-mail: zhangxinping@bjut.edu.cn [Institute of Information Photonics Technology and College of Applied Sciences, Beijing University of Technology, Beijing 100124 (China); Chen, Li [Department of Mathematics and Physics, North China Electric Power University, Hebei 071000 (China)

    2016-01-25

    One- and two-dimensional distributed feedback cavities were constructed on free-standing polymer membranes using spin-coating and lift-off techniques. Low threshold lasing was generated through feedback amplification when the 290-nm membrane device was optically pumped, which was attributed to the strong confinement mechanism provided by the active waveguide layer without a substrate. The free-standing membrane polymer laser is flexible and can be transplanted. Single- and dual-wavelength fiber lasers were achieved by directly attaching the membrane polymer laser on the optical fiber end face. This technique provides potential to fabricate polymer lasers on surfaces with arbitrary shapes.

  19. Block copolymer hollow fiber membranes with catalytic activity and pH-response.

    Science.gov (United States)

    Hilke, Roland; Pradeep, Neelakanda; Madhavan, Poornima; Vainio, Ulla; Behzad, Ali Reza; Sougrat, Rachid; Nunes, Suzana P; Peinemann, Klaus-Viktor

    2013-08-14

    We fabricated block copolymer hollow fiber membranes with self-assembled, shell-side, uniform pore structures. The fibers in these membranes combined pores able to respond to pH and acting as chemical gates that opened above pH 4, and catalytic activity, achieved by the incorporation of gold nanoparticles. We used a dry/wet spinning process to produce the asymmetric hollow fibers and determined the conditions under which the hollow fibers were optimized to create the desired pore morphology and the necessary mechanical stability. To induce ordered micelle assembly in the doped solution, we identified an ideal solvent mixture as confirmed by small-angle X-ray scattering. We then reduced p-nitrophenol with a gold-loaded fiber to confirm the catalytic performance of the membranes.

  20. Block copolymer hollow fiber membranes with catalytic activity and pH-response

    KAUST Repository

    Hilke, Roland

    2013-08-14

    We fabricated block copolymer hollow fiber membranes with self-assembled, shell-side, uniform pore structures. The fibers in these membranes combined pores able to respond to pH and acting as chemical gates that opened above pH 4, and catalytic activity, achieved by the incorporation of gold nanoparticles. We used a dry/wet spinning process to produce the asymmetric hollow fibers and determined the conditions under which the hollow fibers were optimized to create the desired pore morphology and the necessary mechanical stability. To induce ordered micelle assembly in the doped solution, we identified an ideal solvent mixture as confirmed by small-angle X-ray scattering. We then reduced p-nitrophenol with a gold-loaded fiber to confirm the catalytic performance of the membranes. © 2013 American Chemical Society.

  1. Effect of blending HA-g-PLLA on xanthohumol-loaded PLGA fiber membrane.

    Science.gov (United States)

    Qiao, Tiankui; Jiang, Suchen; Song, Ping; Song, Xiaofeng; Liu, Qimin; Wang, Lijuan; Chen, Xuesi

    2016-10-01

    Electropsun poly (lactide-co-glycolide) (PLGA) fiber membrane loaded xanthohumol (XN) has been developed using a co-solvent system of chloroform and dimethylformamide. To enhance its biological functionality as bone tissue engineering scaffolds, 5wt% hydroxyapatite grafted poly (l-lactic acid) (HA-g-PLLA) is blended into the spinning solution. The purpose of the present work is to disclose the effect of blending HA-g-PLLA on the corresponding properties of the medicated fiber membrane including morphology, thermodynamics, wettability, drug release, mechanics as well as cytotoxicity. XN and HA-g-PLLA can be well blended with PLGA to make fibers. Blending HA-g-PLLA not only turns amorphous XN/PLGA fiber membrane into crystal structure, but also changes the membranous wettability. Various medicated membranes exhibit the sustained release profiles. Drug release rate of the ternary membrane with HA-g-PLLA is slower compared to the binary XN/PLGA, and for the ternary membrane, the drug release accelerates with increasing XN content. A model is proposed to account for the drug release process. Tensile testing shows that at 10% of XN, the comprehensive mechanics of the ternary is preferable to the binary. At the same time, these fiber membranes are no cytotoxicity.

  2. DSP based coherent receiver for phase-modulated radio-over-fiber optical links

    DEFF Research Database (Denmark)

    Zibar, Darko; Tafur Monroy, Idelfonso; Peucheret, Christophe

    2008-01-01

    A novel DSP based coherent receiver for phase modulated radio-over-fiber optical links is reported. Using the proposed digital receiver, signal demodulation of 1.25 Gb/s ASK-modulated 10 GHz RF carrier is experimentally demonstrated.......A novel DSP based coherent receiver for phase modulated radio-over-fiber optical links is reported. Using the proposed digital receiver, signal demodulation of 1.25 Gb/s ASK-modulated 10 GHz RF carrier is experimentally demonstrated....

  3. Narrow-line fiber-coupled modules for DPAL pumping

    Science.gov (United States)

    Koenning, Tobias; McCormick, Dan; Irvin, David; Stapleton, Dean; Guiney, Tina; Patterson, Steve

    2015-03-01

    Recent advances in high power diode laser technologies have enabled advanced research on diode pumped alkali metal vapor lasers (DPALs). Due to their low quantum defect, DPALs offer the promise of scalability to very high average power levels while maintaining excellent beam quality. Research is being conducted on a variety of gain media species, requiring different pump wavelengths: near 852nm for cesium, 780nm for rubidium, 766nm for potassium, and 670nm for lithium atoms. The biggest challenge in pumping these materials efficiently is the narrow gain media absorption band of approximately 0.01nm. Typical high power diode lasers achieve spectral widths around 3nm (FWHM) in the near infrared spectrum. Gratings may be used internal or external to the cavity to reduce the spectral width to 0.5nm to 1nm for high power diode laser modules. Recently, experimental results have shown narrower line widths ranging from picometers (pm) at very low power levels to sub-100 picometers for water cooled stacks around 1kW of output power. The focus of this work is a further reduction in the spectral line width of high power diode laser bars emitting at 766nm, with full applicability to other wavelengths of interest. One factor limiting the reduction of the spectral line width is the optical absorption induced thermal gradient inside the volume Bragg grating (VBG). Simulated profiles and demonstrated techniques to minimize thermal gradients will be presented. To enable the next stage of DPAL research, a new series of fiber coupled modules is being introduced featuring greater than 400W from a 600μm core fiber of 0.22NA. The modules achieve a spectral width of <<0.1nm and wavelength tunability of +/- 0.15nm.

  4. Residual intensity modulation in resonator fiber optic gyros with sinusoidal wave phase modulation

    Institute of Scientific and Technical Information of China (English)

    Di-qing YING; Qiang LI; Hui-lian MA; Zhong-he JIN

    2014-01-01

    We present how residual intensity modulation (RIM) affects the performance of a resonator fiber optic gyro (R-FOG) through a sinusoidal wave phase modulation technique. The expression for the R-FOG system’s demodulation curve under RIM is obtained. Through numerical simulation with different RIM coefficients and modulation frequencies, we find that a zero deviation is induced by the RIM effect on the demodulation curve, and this zero deviation varies with the RIM coefficient and modulation frequency. The expression for the system error due to this zero deviation is derived. Simulation results show that the RIM-induced error varies with the RIM coefficient and modulation frequency. There also exists optimum values for the RIM coefficient and modulation frequency to totally eliminate the RIM-induced error, and the error increases as the RIM coefficient or modulation frequency deviates from its optimum value;however, in practical situations, these two parameters would not be exactly fixed but fluctuate from their respective optimum values, and a large system error is induced even if there exists a very small deviation of these two critical parameters from their optimum values. Simulation results indicate that the RIM-induced error should be con-sidered when designing and evaluating an R-FOG system.

  5. Development and characterization of polyacrylonitrile (PAN based carbon hollow fiber membrane

    Directory of Open Access Journals (Sweden)

    Syed Mohd Saufi

    2002-11-01

    Full Text Available This paper reports the development and characterization of polyacrylonitrile (PAN based carbon hollow fiber membrane. Nitrogen was used as an inert gas during pyrolysis of the PAN hollow fiber membrane into carbon membrane. PAN membranes were pyrolyzed at temperature ranging from 500oC to 800oC for 30 minutes of thermal soak time. Scanning Electron Microscope (SEM, Fourier Transform Infrared Spectroscopy (FTIR and gas sorption analysis were applied to characterize the PAN based carbon membrane. Pyrolysis temperature was found to significantly change the structure and properties of carbon membrane. FTIR results concluded that the carbon yield still could be increased by pyrolyzing PAN membranes at temperature higher than 800oC since the existence of other functional group instead of CH group. Gas adsorption analysis showed that the average pore diameter increased up to 800oC.

  6. Matrimid® derived carbon molecular sieve hollow fiber membranes for ethylene/ethane separation

    KAUST Repository

    Xu, Liren

    2011-09-01

    Carbon molecular sieve (CMS) membranes have shown promising separation performance compared to conventional polymeric membranes. Translating the very attractive separation properties from dense films to hollow fibers is important for applying CMS materials in realistic gas separations. The very challenging ethylene/ethane separation is the primary target of this work. Matrimid® derived CMS hollow fiber membranes have been investigated in this work. Resultant CMS fiber showed interesting separation performance for several gas pairs, especially high selectivity for C2H4/C2H6. Our comparative study between dense film and hollow fiber revealed very similar selectivity for both configurations; however, a significant difference exists in the effective separation layer thickness between precursor fibers and their resultant CMS fibers. SEM results showed that the deviation was essentially due to the collapse of the porous substructure of the precursor fiber. Polymer chain flexibility (relatively low glass transition temperature (Tg) for Matrimid® relative to actual CMS formation) appears to be the fundamental cause of substructure collapse. This collapse phenomenon must be addressed in all cases involving intense heat-treatment near or above Tg. We also found that the defect-free property of the precursor fiber was not a simple predictor of CMS fiber performance. Even some precursor fibers with Knudsen diffusion selectivity could be transformed into highly selective CMS fibers for the Matrimid® precursor. To overcome the permeance loss problem caused by substructure collapse, several engineering approaches were considered. Mixed gas permeation results under realistic conditions demonstrate the excellent performance of CMS hollow fiber membrane for the challenging ethylene/ethane separation. © 2011 Elsevier B.V.

  7. Preparation and characterization of thermally stable copoly(phthalazinone biphenyl ether sulfone) hollow fiber ultrafiltration membranes

    Science.gov (United States)

    Liu, Peng; Zhang, Shouhai; Wang, Yutian; Lu, Yan; Jian, Xigao

    2015-04-01

    Novel thermally stable copoly(phthalazinone biphenyl ether sulfone) (PPBES) hollow fiber ultrafiltration (UF) membranes were successfully fabricated by the dry/wet phase inversion technique. The effects of polymer dope formulation (i.e., the PPBES concentration, different types and contents of additives) and fiber spinning conditions (i.e., air gap distance, coagulation bath temperature) on the morphologies and separation performance of PPBES hollow fiber UF membranes were investigated, respectively. It was found that the water flux of hollow fiber membrane decreased with the increase of PPBES concentration or EGME content in casting solution, while the rejection of PEG increased. However, the PPBES hollow fiber UF prepared with LiCl as inorganic small molecule additive exhibited different phenomena. In addition, the decrease of air gap distance or the increase of coagulation bath temperature could improve the water flux of UF membrane while reduce the rejection of PEG. Moreover, the thermal stability of the PPBES hollow fiber UF membranes was investigated. The water flux of PPBES membrane increased dramatically from 155 to 428 L m-2 h-1 without significant decrease of rejection when the temperature of feed solution increased from 20 °C to 95 °C.

  8. Liposome preparation using a hollow fiber membrane contactor--application to spironolactone encapsulation.

    Science.gov (United States)

    Laouini, A; Jaafar-Maalej, C; Sfar, S; Charcosset, C; Fessi, H

    2011-08-30

    In this study, we present a novel liposome preparation technique suitable for the entrapment of pharmaceutical and cosmetic agents. This new method uses a membrane contactor in a hollow fiber configuration. In order to investigate the process, key parameters influence on the liposome characteristics was studied. It has been established that the vesicle size distribution decreased with the organic phase pressure decrease, the phospholipid concentration decreases and the aqueous to organic phase volume ratio increases. Liposomes were filled with a hydrophobic drug model, spironolactone that could be used for a paediatric medication. The mean size of drug-free and drug-loaded liposomes was, respectively, 113 ± 4 nm and 123 ± 3 nm. The zeta potential of drug-free and drug-loaded liposomes was, respectively, -43 ± 0.7 mV and -23 ± 0.6 mV. High entrapment efficiency values were successfully achieved (93 ± 1.12%). Transmission electron microscopy images revealed nanometric sized and spherical shaped oligo-lamellar vesicles. The release profile showed a rapid and complete release within about 5h. Additionally, special attention was paid on process reproducibility and long term lipid vesicles stability. Results confirmed the robustness of the hollow fiber module based technique. Moreover, the technique is simple, fast and has a potential for continuous production of nanosized liposome suspensions at large scale.

  9. Filtering Surface Water with a Polyurethane-based Hollow Fiber Membrane:Effects of Operating Pressure on Membrane Fouling

    Institute of Scientific and Technical Information of China (English)

    赵学辉; 张宏伟; 王捷

    2014-01-01

    Membrane fouling seriously restricts applications of membrane technology. A novel strategy was ap-plied in this study to retard membrane fouling by changing operating pressure with the pressure responsibility membrane. A polyurethane-based hollow fiber membrane was used to treat surface water for evaluating the effect of operating pressure on membrane fouling. Some bench-scale tests in dead-end mode were carried out. In the experi-ments without backwashing, as operating pressure increased, severe membrane fouling occurred on membrane sur-face, while the permeate quality was improved obviously, which is considered to be due to shrinkage deformation. The total resistance, irreversible resistance and reversible resistance under different backwash pressures were de-termined in filtration/backwashing test. With the increase of backwash pressure, the total resistance decreased, and more importantly, the irreversible resistance also decreased, which implies that small particles deposited inside membrane pores and cake layers on membrane surface are effectively removed. Similar results could be obtained in mass balance tests. The results of the present study indicate that the application of pressure responsibility membrane in surface water treatment may be an effective strategy for reducing membrane fouling.

  10. Novel intercore-cladding lithium niobate thin film coated MOEMS fiber sensor/modulator

    Science.gov (United States)

    Jamlson, Tracee L.; Konreich, Phillip; Yu, Chung

    2005-01-01

    A MOEMS fiber modulator/sensor is fabricated by depositing a lithium niobate sol-gel thin film between the core and cladding of a fiber preform. The preform is then drawn into 125-micron fibers. Such a MOEMS modulator design is expected to enhance existing lithium niobate undersea acousto-optic sound wave detectors. In our proposed version, the lithium niobate thin film alters the ordinary silica core/cladding boundary conditions such that, when a stress or strain is applied to the fiber, the core light confinement factor changes, leading to modulation of fiber light transmission. Test results of the lithium niobate embedded fiber with a 1550-nm, 4-mW laser source revealed a reduction in light transmission with applied tension. As a comparison, using the same laser source, an ordinary silica core/cladding fiber did not exhibit any reduction in transmitted light when the same strain was applied. Further experimental work and theoretical analysis is ongoing.

  11. Novel intercore-cladding lithium niobate thin film coated MOEMS fiber sensor/modulator

    Science.gov (United States)

    Jamlson, Tracee L.; Konreich, Phillip; Yu, Chung

    2005-01-01

    A MOEMS fiber modulator/sensor is fabricated by depositing a lithium niobate sol-gel thin film between the core and cladding of a fiber preform. The preform is then drawn into 125-micron fibers. Such a MOEMS modulator design is expected to enhance existing lithium niobate undersea acousto-optic sound wave detectors. In our proposed version, the lithium niobate thin film alters the ordinary silica core/cladding boundary conditions such that, when a stress or strain is applied to the fiber, the core light confinement factor changes, leading to modulation of fiber light transmission. Test results of the lithium niobate embedded fiber with a 1550-nm, 4-mW laser source revealed a reduction in light transmission with applied tension. As a comparison, using the same laser source, an ordinary silica core/cladding fiber did not exhibit any reduction in transmitted light when the same strain was applied. Further experimental work and theoretical analysis is ongoing.

  12. Modeling of hydrodynamics in hollow fiber membrane bioreactor for mammalian cells cultivation

    Directory of Open Access Journals (Sweden)

    N. V. Menshutina

    2016-01-01

    Full Text Available The mathematical modelling in CFD-packages are powerfull instrument for design and calculation of any engineering tasks. CFD-package contains the set of programs that allow to model the different objects behavior based on the mathematical lows. ANSYS Fluent are widely used for modelling of biotechnological and chemical-technological processes. This package is convenient to describe their hydrodynamics. As cell cultivation is one of the actual scientific direction in modern biotechnology ANSYS Fluent was used to create the model of hollow fiber membrane bioreactor. The fibers are hollow cylindrical membrane to be used for cell cultivation. The criterion of process effectiveness for cell growth is full filling of the membrane surface by cells in the bioreactor. While the cell growth the fiber permeability is decreased which effects to feed flow through membrane pores. The specific feature of this process is to ensure such feed flow to deliver the optimal nutrition for the cells on the external membrane surface. The velocity distribution inside the fiber and in all bioreactor as a whole has been calculated based on mass an impulse conservation equations taking into account the mathematical model assumptions. The hydrodynamics analysis in hollow fiber membrane bioreactor is described by the three-dimensional model created in ANSYS Fluent. The specific features of one membrane model are considered and for whole bioreactor too.

  13. Lipid-protein interactions in plasma membranes of fiber cells isolated from the human eye lens.

    Science.gov (United States)

    Raguz, Marija; Mainali, Laxman; O'Brien, William J; Subczynski, Witold K

    2014-03-01

    The protein content in human lens membranes is extremely high, increases with age, and is higher in the nucleus as compared with the cortex, which should strongly affect the organization and properties of the lipid bilayer portion of intact membranes. To assess these effects, the intact cortical and nuclear fiber cell plasma membranes isolated from human lenses from 41- to 60-year-old donors were studied using electron paramagnetic resonance spin-labeling methods. Results were compared with those obtained for lens lipid membranes prepared from total lipid extracts from human eyes of the same age group [Mainali, L., Raguz, M., O'Brien, W. J., and Subczynski, W. K. (2013) Biochim. Biophys. Acta]. Differences were considered to be mainly due to the effect of membrane proteins. The lipid-bilayer portions of intact membranes were significantly less fluid than lipid bilayers of lens lipid membranes, prepared without proteins. The intact membranes were found to contain three distinct lipid environments termed the bulk lipid domain, boundary lipid domain, and trapped lipid domain. However, the cholesterol bilayer domain, which was detected in cortical and nuclear lens lipid membranes, was not detected in intact membranes. The relative amounts of bulk and trapped lipids were evaluated. The amount of lipids in domains uniquely formed due to the presence of membrane proteins was greater in nuclear membranes than in cortical membranes. Thus, it is evident that the rigidity of nuclear membranes is greater than that of cortical membranes. Also the permeability coefficients for oxygen measured in domains of nuclear membranes were significantly lower than appropriate coefficients measured in cortical membranes. Relationships between the organization of lipids into lipid domains in fiber cells plasma membranes and the organization of membrane proteins are discussed.

  14. Modulation instability of dispersion-shifted fiber couplers

    Institute of Scientific and Technical Information of China (English)

    ZHOU Yan-yong; JIA Wei-guo; HAN Ying-ming; YING Chun; BAO Hong-mei

    2008-01-01

    The nonlinear coupled-mode equations are rewritten by even and odd modes. We study modulation instability (MI) of dispersion-shifted fiber couplers when either even or odd mode is launched alone by using zero-dispersion waveleng threlatively long (quasi-cw) pulses. The result shows that there are new types of MI in both the normal-dispersion and the anomalous-dispersion regimes. MI is concerned with forth-order dispersion and has no relation with third-order dispersion.Quasi-cw can be changed into pulses array under certain conditions. We can extract super short pulse from this. Furthermore,the bandwidth of gain spectra widens and its strength accretes as the input power increases.

  15. The nonfermentable dietary fiber hydroxypropyl methylcellulose modulates intestinal microbiota.

    Science.gov (United States)

    Cox, Laura M; Cho, Ilseung; Young, Scott A; Anderson, W H Kerr; Waters, Bartholomew J; Hung, Shao-Ching; Gao, Zhan; Mahana, Douglas; Bihan, Monika; Alekseyenko, Alexander V; Methé, Barbara A; Blaser, Martin J

    2013-02-01

    Diet influences host metabolism and intestinal microbiota; however, detailed understanding of this tripartite interaction is limited. To determine whether the nonfermentable fiber hydroxypropyl methylcellulose (HPMC) could alter the intestinal microbiota and whether such changes correlated with metabolic improvements, C57B/L6 mice were normalized to a high-fat diet (HFD), then either maintained on HFD (control), or switched to HFD supplemented with 10% HPMC, or a low-fat diet (LFD). Compared to control treatment, both LFD and HPMC reduced weight gain (11.8 and 5.7 g, respectively), plasma cholesterol (23.1 and 19.6%), and liver triglycerides (73.1 and 44.6%), and, as revealed by 454-pyrosequencing of the microbial 16S rRNA gene, decreased microbial α-diversity and differentially altered intestinal microbiota. Both LFD and HPMC increased intestinal Erysipelotrichaceae (7.3- and 12.4-fold) and decreased Lachnospiraceae (2.0- and 2.7-fold), while only HPMC increased Peptostreptococcaceae (3.4-fold) and decreased Ruminococcaceae (2.7-fold). Specific microorganisms were directly linked with weight change and metabolic parameters in HPMC and HFD mice, but not in LFD mice, indicating that the intestinal microbiota may play differing roles during the two dietary modulations. This work indicates that HPMC is a potential prebiotic fiber that influences intestinal microbiota and improves host metabolism.

  16. Generalized modulational instability in multimode fibers: wideband multimode parametric amplification

    CERN Document Server

    Guasoni, M

    2015-01-01

    In this paper intermodal modulational instability (IM-MI) is analyzed in a multimode fiber where several spatial and polarization modes propagate. The coupled nonlinear Schr\\"{o}dinger equations describing the modal evolution in the fiber are linearized and reduced to an eigenvalue problem. As a result, the amplification of each mode can be described by means of the eigenvalues and eigenvectors of a matrix that stores the information about the dispersion properties of the modes and the modal power distribution of the pump. Some useful analytical formulas are also provided that estimate the modal amplification as function of the system parameters. Finally, the impact of third-order dispersion and of absorbtion losses is evaluated, which reveals some surprising phenomena into the IM-MI dynamics. These outcomes generalize previous studies on bimodal-MI, related to the interaction between 2 spatial or polarization modes, to the most general case of $N>2$ interacting modes. Moreover, they pave the way towards the ...

  17. Humidity control during bell pepper storage, using a hollow fiber membrane contractor system

    NARCIS (Netherlands)

    Dijkink, B.H.; Tomassen, M.M.M.; Willemsen, J.H.A.; Doorn, van W.G.

    2004-01-01

    Green bell peppers (Capsicum annuum cv. Cardio) were stored in open crates at 5 degreesC, using a novel system for maintenance of relative humidity (RH). A hollow fiber membrane contactor allowed adequate transfer of water vapor between the air in the storage room and a liquid desiccant. The membran

  18. Humidity control during bell pepper storage, using a hollow fiber membrane contractor system

    NARCIS (Netherlands)

    Dijkink, B.H.; Tomassen, M.M.M.; Willemsen, J.H.A.; Doorn, van W.G.

    2004-01-01

    Green bell peppers (Capsicum annuum cv. Cardio) were stored in open crates at 5 degreesC, using a novel system for maintenance of relative humidity (RH). A hollow fiber membrane contactor allowed adequate transfer of water vapor between the air in the storage room and a liquid desiccant. The membran

  19. Membrane distillation with porous metal hollow fibers for the concentration of thermo-sensitive solutions

    NARCIS (Netherlands)

    Shukla, S.

    2014-01-01

    This thesis presents an original approach for the concentration of thermo-sensitive solutions: the Sweep Gas Membrane Distillation (SGMD) process. A new membrane contactor with metallic hollow fibers has been designed and allows the distillation process to be operational at low temperature. Heat is

  20. Particle-loaded hollow-fiber membrane adsorbers for lysozyme separation

    NARCIS (Netherlands)

    Avramescu, M.E.; Borneman, Zandrie; Wessling, Matthias

    2008-01-01

    The separation of lysozyme (LZ), a valuable enzyme naturally present in chicken egg white, was carried out using a new type of ion exchange hollow-fiber membranes. Functionalities were incorporated into the polymeric membranes by dispersing ion-exchange resins (IERs) in a microporous structure

  1. Characterization of hollow fiber hemo-dialysis membranes: pore size distribution and performance

    NARCIS (Netherlands)

    Broek, A.P.; Broek, Arnold P.; Teunis, Herman A.; Teunis, Hermannus A.; Bargeman, D.; Bargeman, Derk; Sprengers, Erik D.; Smolders, C.A.; Smolders, C.A.

    1992-01-01

    The effect of two commonly used sterilization methods for artificial kidneys on the morphology and performance of hollow fiber Hemophan® hemodialysis membranes was studied. A relatively new membrane characterization method, thermoporometry, was used to determine the pore size distributions and

  2. Highly scalable ZIF-based mixed-matrix hollow fiber membranes for advanced hydrocarbon separations

    KAUST Repository

    Zhang, Chen

    2014-05-29

    ZIF-8/6FDA-DAM, a proven mixed-matrix material that demonstrated remarkably enhanced C3H6/C3H8 selectivity in dense film geometry, was extended to scalable hollow fiber geometry in the current work. We successfully formed dual-layer ZIF-8/6FDA-DAM mixed-matrix hollow fiber membranes with ZIF-8 nanoparticle loading up to 30 wt % using the conventional dry-jet/wet-quench fiber spinning technique. The mixed-matrix hollow fibers showed significantly enhanced C3H6/C3H8 selectivity that was consistent with mixed-matrix dense films. Critical variables controlling successful formation of mixed-matrix hollow fiber membranes with desirable morphology and attractive transport properties were discussed. Furthermore, the effects of coating materials on selectivity recovery of partially defective fibers were investigated. To our best knowledge, this is the first article reporting successful formation of high-loading mixed-matrix hollow fiber membranes with significantly enhanced selectivity for separation of condensable olefin/paraffin mixtures. Therefore, it represents a major step in the research area of advanced mixed-matrix membranes. © 2014 American Institute of Chemical Engineers.

  3. Transport of Carbonate Ions by Novel Cellulose Fiber Supported Solid Membrane

    Directory of Open Access Journals (Sweden)

    A. G. Gaikwad

    2012-06-01

    Full Text Available Transport of carbonate ions was explored through fiber supported solid membrane. A novel fiber supported solid membrane was prepared by chemical modification of cellulose fiber with citric acid, 2′2-bipyridine and magnesium carbonate. The factors affecting the permeability of carbonate ions such as immobilization of citric acid-magnesium metal ion -2′2-bipyridine complex (0 to 2.5 mmol/g range over cellulose fiber, carbon-ate ion concentration in source phase and NaOH concentration in receiving phase were investigated. Ki-netic of carbonate, sulfate, and nitrate ions was investigated through fiber supported solid membrane. Transport of carbonate ions with/without bubbling of CO2 (0 to 10 ml/min in source phase was explored from source to receiving phase. The novel idea is to explore the adsorptive transport of CO2 from source to receiving phase through cellulose fiber containing magnesium metal ion organic framework. Copyright © 2012 BCREC UNDIP. All rights reserved.Received: 25th November 2011; Revised: 17th December 2011; Accepted: 19th December 2011[How to Cite: A.G. Gaikwad. (2012. Transport of Carbonate Ions by Novel Cellulose Fiber Supported Solid Membrane. Bulletin of Chemical Reaction Engineering & Catalysis, 7 (1: 49– 57.  doi:10.9767/bcrec.7.1.1225.49-57][How to Link / DOI: http://dx.doi.org/10.9767/bcrec.7.1.1225.49-57 ] | View in 

  4. Effects of CO 2 on a High Performance Hollow-Fiber Membrane for Natural Gas Purification

    KAUST Repository

    Omole, Imona C.

    2010-05-19

    A 6FDA-based, cross-linkable polyimide was characterized in the form of a defect-free asymmetric hollow-fiber membrane. The novel membrane was cross-linked at various temperatures and tested for natural gas purification in the presence of high CO2 partial pressures. The cross-linked membrane material shows high intrinsic separation performance for CO2 and CH4 (selectivity ∼49, CO2 permeability ∼161 barrer, with a feed at 65 psia, 35 °C, and 10% CO2). Cross-linked asymmetric hollow-fiber membranes made from the material show good resistance to CO2-induced plasticization. Carbon dioxide partial pressures as high as ∼400 psia were employed, and the membrane was shown to be promisingly stable under these aggressive conditions. The performance of the membrane was also analyzed using the dual-mode sorption/transport model. © 2010 American Chemical Society.

  5. Extracellular ultrathin fibers sensitive to intracellular reactive oxygen species: Formation of intercellular membrane bridges

    Energy Technology Data Exchange (ETDEWEB)

    Jung, Se-Hui; Park, Jin-Young; Joo, Jung-Hoon; Kim, Young-Myeong; Ha, Kwon-Soo, E-mail: ksha@kangwon.ac.kr

    2011-07-15

    Membrane bridges are key cellular structures involved in intercellular communication; however, dynamics for their formation are not well understood. We demonstrated the formation and regulation of novel extracellular ultrathin fibers in NIH3T3 cells using confocal and atomic force microscopy. At adjacent regions of neighboring cells, phorbol 12-myristate 13-acetate (PMA) and glucose oxidase induced ultrathin fiber formation, which was prevented by Trolox, a reactive oxygen species (ROS) scavenger. The height of ROS-sensitive ultrathin fibers ranged from 2 to 4 nm. PMA-induced formation of ultrathin fibers was inhibited by cytochalasin D, but not by Taxol or colchicine, indicating that ultrathin fibers mainly comprise microfilaments. PMA-induced ultrathin fibers underwent dynamic structural changes, resulting in formation of intercellular membrane bridges. Thus, these fibers are formed by a mechanism(s) involving ROS and involved in formation of intercellular membrane bridges. Furthermore, ultrastructural imaging of ultrathin fibers may contribute to understanding the diverse mechanisms of cell-to-cell communication and the intercellular transfer of biomolecules, including proteins and cell organelles.

  6. Modulation of hematopoiesis by lymphocyte membrane-derived components.

    Science.gov (United States)

    Guha, A; Mason, R P; Chen, L; Tuck, D P; Dainiak, N

    1994-04-01

    Membrane bound erythroid burst-promoting activity (mBPA) is an integral membrane protein that is present on normal B-cells and some activated T-cells, that induces burst-forming units-erythroid (BFU-E) when cultured with human erythropoietin (rHuEpo). Plasma membranes and vesicles shed from the leukemic A-1 cell line express mBPA. This activity derived from both A-1 cells and normal B-cells can be immunoadsorbed by the D3A4 antibody raised against mBPA. In this study, we demonstrate that interferon-gamma (IFN-gamma) suppresses BFU-E proliferation when added directly to culture of normal human bone marrow cells and in the absence and presence of A-1 cells. However, FACS analysis reveals that IFN-gamma enhances the surface expression of mBPA on A-1 cells. The role of IFN-gamma in modulating erythropoiesis in vitro is discussed with respect to the role of shedding membrane-derived vesicles from the B-cell surface.

  7. Preparation of hydrophilic vinyl chloride copolymer hollow fiber membranes with antifouling properties

    Science.gov (United States)

    Rajabzadeh, Saeid; Sano, Rie; Ishigami, Toru; Kakihana, Yuriko; Ohmukai, Yoshikage; Matsuyama, Hideto

    2015-01-01

    Hydrophilic vinyl chloride copolymer hollow fiber membranes with antifouling properties were prepared from brominated vinyl chloride-hydroxyethyl methacrylate copolymer (poly(VC-co-HEMA-Br)). The base membrane was grafted with two different zwitterionic monomers, (2-methacryloyloxyethylphosphorylcholine) (MPC) and [2-(methacryloyloxy) ethyl] dimethyl (3-sulfopropyl) ammonium hydroxide) (MEDSAH), and poly(ethylene glycol) methyl ether methacrylate (PEGMA). The effect of the grafting on the base membrane hydrophilicity and antifouling properties was investigated. For comparison of the results, the pure water permeabilities and pore sizes at the outer surfaces of the grafted hollow fiber membranes were controlled to be similar. A poly(VC-co-HEMA-Br) hollow fiber membrane with similar pure water permeability and pore size was also prepared as a control membrane. A BSA solution was used as a model fouling solution for evaluation of the antifouling properties. Grafting with zwitterionic monomers and PEGMA improved the antifouling properties compared with the control membrane. The PEGMA grafted membrane showed the best antifouling properties among the grafted membranes

  8. Modulation and interactions of charged biomimetic membranes with bivalent ions

    Science.gov (United States)

    Kazadi Badiambile, Adolphe

    biomolecules in a dynamic environment and the lack of appropriate physical and biochemical tools. In contrast, biomimetic membrane models that rely on the amphiphilic properties of phospholipids are powerful tools that enable the study of these molecules in vitro. By having control over the different experimental parameters such as temperature and pH, reliable and repeatable experimental conditions can be created. One of the key questions I investigated in this thesis is related to the clustering mechanism of PtdIns(4, 5)P2 into pools or aggregates that enable independent cellular control of this species by geometric separation. The lateral aggregation of PtdIns(4, 5)P2 and its underlying physical causes is still a matter of debate. In the first part of this thesis I introduce the general information on lipid membranes with a special focus on the PtdIns family and their associated signaling events. In addition, I explain the Langmuir-Blodgett film balance (LB) system as tool to study lipid membranes and lipid interactions. In the second chapter, I describe my work on the lateral compressibility of PtdIns(4, 5)P2, PtdIns and DOPG monolayers and its modulation by bivalent ions using Langmuir monolayers. In addition, a theoretical framework of compressibility that depends on a surface potential induced by a planar layer of charged molecules and ions in the bulk was provided. In the third part, I present my work on the excess Gibbs free energy of the lipid systems PtdIns(4, 5)P2 --POPC, PtdIns(4, 5)P2, and POPC as they are modulated by bivalent ions. In the fourth part, I report on my foray in engineering a light-based system that relies on different dye properties to simulate calcium induced calcium release (CICR) that occurs in many cell types. In the final chapter, I provide a general conclusion and present directions for future research that would build on my findings.

  9. Property and Shape Modulation of Carbon Fibers Using Lasers.

    Science.gov (United States)

    Blaker, Jonny J; Anthony, David B; Tang, Guang; Shamsuddin, Siti-Ros; Kalinka, Gerhard; Weinrich, Malte; Abdolvand, Amin; Shaffer, Milo S P; Bismarck, Alexander

    2016-06-29

    An exciting challenge is to create unduloid-reinforcing fibers with tailored dimensions to produce synthetic composites with improved toughness and increased ductility. Continuous carbon fibers, the state-of-the-art reinforcement for structural composites, were modified via controlled laser irradiation to result in expanded outwardly tapered regions, as well as fibers with Q-tip (cotton-bud) end shapes. A pulsed laser treatment was used to introduce damage at the single carbon fiber level, creating expanded regions at predetermined points along the lengths of continuous carbon fibers, while maintaining much of their stiffness. The range of produced shapes was quantified and correlated to single fiber tensile properties. Mapped Raman spectroscopy was used to elucidate the local compositional and structural changes. Irradiation conditions were adjusted to create a swollen weakened region, such that fiber failure occurred in the laser treated region producing two fiber ends with outwardly tapered ends. Loading the tapered fibers allows for viscoelastic energy dissipation during fiber pull-out by enhanced friction as the fibers plough through a matrix. In these tapered fibers, diameters were locally increased up to 53%, forming outward taper angles of up to 1.8°. The tensile strength and strain to failure of the modified fibers were significantly reduced, by 75% and 55%, respectively, ensuring localization of the break in the expanded region; however, the fiber stiffness was only reduced by 17%. Using harsher irradiation conditions, carbon fibers were completely cut, resulting in cotton-bud fiber end shapes. Single fiber pull-out tests performed using these fibers revealed a 6.75-fold increase in work of pull-out compared to pristine carbon fibers. Controlled laser irradiation is a route to modify the shape of continuous carbon fibers along their lengths, as well as to cut them into controlled lengths leaving tapered or cotton-bud shapes.

  10. Shell-side dispersion coefficients in a rectangular cross-flow hollow fibre membrane module

    NARCIS (Netherlands)

    Dindore, V. Y.; Cents, A. H. G.; Brilman, D. W. F.; Versteeg, G. F.

    2005-01-01

    Membrane processes utilizing hollow fibre membrane modules are gaining increased interest in many industrial applications. However, these modules suffer from shell-side maldistribution and bypassing which results in a loss in efficiency. The shell-side mass transfer performance of these membrane mod

  11. Shell-side dispersion coefficients in a rectangular cross-flow hollow fibre membrane module

    NARCIS (Netherlands)

    Dindore, V. Y.; Cents, A. H. G.; Brilman, D. W. F.; Versteeg, G. F.

    2005-01-01

    Membrane processes utilizing hollow fibre membrane modules are gaining increased interest in many industrial applications. However, these modules suffer from shell-side maldistribution and bypassing which results in a loss in efficiency. The shell-side mass transfer performance of these membrane

  12. Bidirectional fiber-wireless and fiber-IVLLC integrated system based on polarization-orthogonal modulation scheme.

    Science.gov (United States)

    Lu, Hai-Han; Li, Chung-Yi; Chen, Hwan-Wei; Ho, Chun-Ming; Cheng, Ming-Te; Huang, Sheng-Jhe; Yang, Zih-Yi; Lin, Xin-Yao

    2016-07-25

    A bidirectional fiber-wireless and fiber-invisible laser light communication (IVLLC) integrated system that employs polarization-orthogonal modulation scheme for hybrid cable television (CATV)/microwave (MW)/millimeter-wave (MMW)/baseband (BB) signal transmission is proposed and demonstrated. To our knowledge, it is the first one that adopts a polarization-orthogonal modulation scheme in a bidirectional fiber-wireless and fiber-IVLLC integrated system with hybrid CATV/MW/MMW/BB signal. For downlink transmission, carrier-to-noise ratio (CNR), composite second-order (CSO), composite triple-beat (CTB), and bit error rate (BER) perform well over 40-km single-mode fiber (SMF) and 10-m RF/50-m optical wireless transport scenarios. For uplink transmission, good BER performance is obtained over 40-km SMF and 50-m optical wireless transport scenario. Such a bidirectional fiber-wireless and fiber-IVLLC integrated system for hybrid CATV/MW/MMW/BB signal transmission will be an attractive alternative for providing broadband integrated services, including CATV, Internet, and telecommunication services. It is shown to be a prominent one to present the advancements for the convergence of fiber backbone and RF/optical wireless feeder.

  13. Robust BPSK Impulse Radio UWB-over-Fiber Systems Using Optical Phase Modulation

    DEFF Research Database (Denmark)

    Pham, Tien Thang; Guerrero Gonzalez, Neil; Yu, Xianbin

    2011-01-01

    The impact of fiber dispersion on the performance of optical phase modulated impulse-radio-ultrawideband (IR-UWB) signals is experimentally investigated. 2Gbps BPSK IR-UWB over 78km fiber transmission is successfully achieved by using digital coherent detection......The impact of fiber dispersion on the performance of optical phase modulated impulse-radio-ultrawideband (IR-UWB) signals is experimentally investigated. 2Gbps BPSK IR-UWB over 78km fiber transmission is successfully achieved by using digital coherent detection...

  14. Modulation instabilities in randomly birefringent two-mode optical fibers

    Science.gov (United States)

    Li, Jin-Hua; Ren, Hai-Dong; Pei, Shi-Xin; Cao, Zhao-Lou; Xian, Feng-Lin

    2016-12-01

    Modulation instabilities in the randomly birefringent two-mode optical fibers (RB-TMFs) are analyzed in detail by accounting the effects of the differential mode group delay (DMGD) and group velocity dispersion (GVD) ratio between the two modes, both of which are absent in the randomly birefringent single-mode optical fibers (RB-SMFs). New MI characteristics are found in both normal and anomalous dispersion regimes. For the normal dispersion, without DMGD, no MI exists. With DMGD, a completely new MI band is generated as long as the total power is smaller than a critical total power value, named by Pcr, which increases significantly with the increment of DMGD, and reduces dramatically as GVD ratio and power ratio between the two modes increases. For the anomalous dispersion, there is one MI band without DMGD. In the presence of DMGD, the MI gain is reduced generally. On the other hand, there also exists a critical total power (Pcr), which increases (decreases) distinctly with the increment of DMGD (GVD ratio of the two modes) but varies complicatedly with the power ratio between the two modes. Two MI bands are present for total power smaller than Pcr, and the dominant band can be switched between the low and high frequency bands by adjusting the power ratio between the two modes. The MI analysis in this paper is verified by numerical simulation. Project supported by the Natural Science Foundation of Jiangsu Provincial Universities (Grant No. 14KJB140009), the National Natural Science Foundation of China (Grant No. 11447113), and the Startup Foundation for Introducing Talent of NUIST (Grant No. 2241131301064).

  15. Formation of defect-free 6FDA-DAM asymmetric hollow fiber membranes for gas separations

    KAUST Repository

    Xu, Liren

    2014-06-01

    This paper reports the formation of defect-free 6FDA-DAM asymmetric hollow fiber membranes. 6FDA-polyimides are of great interest for advanced gas separation membranes, and 6FDA-DAM polyimide is a representative polymer in this family with attractive dense film properties for several potential applications. The work reported here for the 6FDA-DAM polyimide provides insight for the challenging fabrication of defect-free asymmetric hollow fiber membranes for this class of 6FDA-polyimides, which behave rather different from lower free volume polymers. Specifically, the 6FDA based materials show relatively slow phase separation rate in water quench baths, which presents a challenge for fiber spinning. For convenience, we refer to the behavior as more "non-solvent resistant" in comparison to other lower free volume polymers, since the binodal phase boundary is displaced further from the conventional position near the pure polymer-solvent axis on a ternary phase diagram in conventional polymers like Matrimid® and Ultem®. The addition of lithium nitrate to promote phase separation has a useful impact on 6FDA-DAM asymmetric hollow fiber formation. 6FDA-DAM phase diagrams using ethanol and water as non-solvent are reported, and it was found that water is less desirable as a non-solvent dope additive for defect-free fiber spinning. Phase diagrams are also reported for 6FDA-DAM dope formulation with and without the addition of lithium nitrate, and defect-free asymmetric hollow fiber membranes are reported for both cases. The effect of polymer molecular weight on defect-free fiber spinning was also investigated. Gas transport properties and morphology of hollow fibers were characterized. With several thorough case studies, this work provides a systematic guideline for defect-free fiber formation from 6FDA-polymers. © 2014 Elsevier B.V.

  16. Membrane lipids tune synaptic transmission by direct modulation of presynaptic potassium channels.

    Science.gov (United States)

    Carta, Mario; Lanore, Frederic; Rebola, Nelson; Szabo, Zsolt; Da Silva, Silvia Viana; Lourenço, Joana; Verraes, Agathe; Nadler, André; Schultz, Carsten; Blanchet, Christophe; Mulle, Christophe

    2014-02-19

    Voltage-gated potassium (Kv) channels are involved in action potential (AP) repolarization in excitable cells. Exogenous application of membrane-derived lipids, such as arachidonic acid (AA), regulates the gating of Kv channels. Whether membrane-derived lipids released under physiological conditions have an impact on neuronal coding through this mechanism is unknown. We show that AA released in an activity-dependent manner from postsynaptic hippocampal CA3 pyramidal cells acts as retrograde messenger, inducing a robust facilitation of mossy fiber (Mf) synaptic transmission over several minutes. AA acts by broadening presynaptic APs through the direct modulation of Kv channels. This form of short-term plasticity can be triggered when postsynaptic cell fires with physiologically relevant patterns and sets the threshold for the induction of the presynaptic form of long-term potentiation (LTP) at hippocampal Mf synapses. Hence, direct modulation of presynaptic Kv channels by activity-dependent release of lipids serves as a physiological mechanism for tuning synaptic transmission.

  17. Characterization of Thermally Cross-Linkable Hollow Fiber Membranes for Natural Gas Separation

    KAUST Repository

    Chen, Chien-Chiang

    2013-01-23

    The performance of thermally cross-linkable hollow fiber membranes for CO2/CH4 separation and the membrane stability against CO2 plasticization was investigated. The fiber membranes were thermally cross-linked at various conditions. Cross-linking temperature was found to have a significant effect, while shorter soak time and the presence of trace oxidizer (O2 or N2O) had a negligible effect. The cross-linked fibers were tested using high CO2 content feeds (50-70% CO2) at a variety of feed pressures (up to 1000 psia), temperatures, and permeate pressures (up to 100 psia) to evaluate membrane performance under various realistic operating conditions. The results demonstrated that cross-linking improves membrane selectivity and effectively eliminates swelling-induced hydrocarbon loss at high pressures. Excellent stability under aggressive feeds (with CO2 partial pressure up to 700 psia) suggests that cross-linked hollow fiber membranes have great potential for use in diverse aggressive applications, even beyond the CO2/CH4 example explored in this work. © 2012 American Chemical Society.

  18. Preparation and characterization of regenerated cellulose membranes from natural cotton fiber

    Directory of Open Access Journals (Sweden)

    Yanjuan CAO

    2015-06-01

    Full Text Available A series of organic solutions with different cellulose concentrations are prepared by dissolving natural cotton fibers in lithium chloride/dimethyl acetamide (LiCl/DMAC solvent system after the activation of cotton fibers. Under different coagulating bath, the regenerated cellulose membranes are formed in two kinds of coagulation baths, and two coating methods including high-speed spin technique (KW-4A spin coating machine and low-speed scraping (AFA-Ⅱ Film Applicator are selected in this paper. The macromolecular structure, mechanical properties, crystallinity, thermal stability and wetting property of the regenerated cellulose membrane are characterized by Scanning Electron Microscope(SEM, Fourier Transform Infrared Spectroscopy (FT-IR,X-ray diffraction (XRD, Thermogravimetric analysis (TG and contacting angle tester. The effects of mass fraction, coagulation bath type, membrane forming process on the regenerated membrane properties are investigated. Experimental results show that the performance of regenerated cellulose membrane is relatively excellent under the condition of using the KW-4A high-speed spin method, water coagulation bath, and when mass fraction of cellulose is 3.5%. The crystallinity of the regenerated cellulose membrane changes a lot compared with natural cotton fibers. The variation trend of thermal stability is similar with that of cotton fiber. But thermal stability is reduced to some degree, while the wetting ability is improved obviously.

  19. Q-switching of an all-fiber laser by acousto-optic modulation of a fiber Bragg grating

    Science.gov (United States)

    Delgado-Pinar, M.; Zalvidea, D.; Diez, A.; Perez-Millan, P.; Andres, M.

    2006-02-01

    We report active Q-switching of an all-fiber laser using a Bragg grating based acousto-optic modulator. Q-switching is performed by modulating a fiber Bragg grating with an extensional acoustic wave. The acoustic wave modulates periodically the effective index profile of the FBG and changes its reflection features. This allows controlling the Q-factor of the cavity. Using 1 m of 300 ppm erbium-doped fiber and a maximum pump power of 180 mW, Q-switch pulses of 10 W of peak power and 82 ns wide were generated. The pulse repetition rate of the laser can be continuously varied from few Hz up to 62.5 kHz.

  20. Morphological studies on the culture of kidney epithelial cells in a fiber-in-fiber bioreactor design with hollow fiber membranes.

    Science.gov (United States)

    Fey-Lamprecht, F; Albrecht, W; Groth, T; Weigel, T; Gross, U

    2003-05-01

    A hollow fiber-in-fiber-based bioreactor system was tested for the applicability to host kidney epithelial cells as a model system for a bioartificial kidney. Hollow fibers were prepared from polyacrylonitrile (PAN), polysulfone-polyvinylpyrollidinone (PVP) blend (PSU) and poly(acrylonitrile-N-vinylpyrollidinone) copolymer P(AN-NVP). Hollow fibers with smaller and larger diameters were prepared so that the smaller fitted into the larger, with a distance of 50-100 microm in between. The following material combinations as outer and inner fiber were applied: PAN-PAN; PSU-PSU, PSU-P(AN-NVP). Madin-Darby kidney epithelial cells (MDCK) were seeded in the interfiber space and cultured for a period up to 14 days. Light, scanning, and transmission electron microscopy were used to follow the adhesion and growth of cells, and to characterize their morphology. As a result, we found that MDCK cells were able to grow in the interfiber space in mono- and multilayers without signs of systemic degeneration. Comparison of the different materials showed that PAN and P(AN-NVP) provided the best growth conditions, indicated by a tight attachment of cells on hollow fiber membrane, and subsequent proliferation and development of structural elements of normal epithelia, such as tight junctions and microvilli. In conclusion, the fiber-in-fiber design seems to be an interesting system for the construction of a bioartificial kidney. Copyright 2003 Wiley Periodicals, Inc.

  1. Plasticization-resistant hollow fiber membranes for CO2/CH4 separation based on a thermally crosslinkable polyimide

    KAUST Repository

    Chen, Chien-Chiang

    2011-10-01

    Decarboxylation-induced thermal crosslinking has been demonstrated to be effective for stabilizing membranes against plasticization in dense films. This study extends this promising crosslinking approach from dense films to industrially relevant asymmetric hollow fiber membranes. Crosslinkable asymmetric hollow fiber membranes were spun from a carboxylic acid containing polyimide, 6FDA-DAM:DABA. Dope and spinning conditions were optimized to obtain fibers with a defect-free selective skin layer. It is found that slightly defective fibers suffered severe selectivity loss after thermal crosslinking, suggesting that defect-free property is essential to the performance of the resulting crosslinked hollow fiber membranes. The crosslinked fibers were tested for CO 2/CH 4 separation. The excellent plasticization resistance under high pressure feeds (with highest CO 2 partial pressure of 400psia) suggests that these robust membranes are promising for aggressive natural gas purification. © 2011 Elsevier B.V.

  2. Enriched glucose and dextrin mannitol-based media modulates fibroblast behavior on bacterial cellulose membranes

    Energy Technology Data Exchange (ETDEWEB)

    Stumpf, Taisa R.; Pértile, Renata A.N. [Integrated Technologies Laboratory, Department of Chemical and Food Engineering (Brazil); Rambo, Carlos R., E-mail: rambo@intelab.ufsc.br [Department of Electrical Engineering, Federal University of Santa Catarina, Florianópolis 88040-900 (Brazil); Porto, Luismar M. [Integrated Technologies Laboratory, Department of Chemical and Food Engineering (Brazil)

    2013-12-01

    Bacterial cellulose (BC) produced by Gluconacetobacter hansenii is a suitable biopolymer for biomedical applications. In order to modulate the properties of BC and expand its use as substrate for tissue engineering mainly in the form of biomembranes, glucose or dextrin were added into a BC fermentation mannitol-based medium (BCGl and BCDe, respectively) under static culture conditions. SEM images showed effects on fiber density and porosity on both sides of the BC membranes. Both enriched media decreased the BET surface area, water holding capacity, and rehydration rate. Fourier transform infrared (attenuated total reflectance mode) spectroscopy (FTIR-ATR) analysis revealed no change in the chemical structure of BC. L929 fibroblast cells were seeded on all BC-based membranes and evaluated in aspects of cell adhesion, proliferation and morphology. BCG1 membranes showed the highest biological performance and hold promise for the use in tissue engineering applications. - Highlights: • Glucose and dextrin were used to modify culture media for BC production. • Microarchitecture of BC was different depending on the enriching agent. • Fibroblasts adhered on the surface of BC modified microarchitectures. • Fibroblasts adhered on glucose modified BC exhibited healthy cell morphology.

  3. Scale-up of NaA zeolite membranes onα-Al2O3 hollow fibers by a secondary growth method with vacuum seeding

    Institute of Scientific and Technical Information of China (English)

    Yanmei Liu; Xuerui Wang; Yuting Zhang; Yong He; Xuehong Gu

    2015-01-01

    NaA zeolite membranes were prepared by secondary growth method on the outer surface ofα-Al2O3 hollow fiber supports. Vacuum seeding method was used for planting zeolite seeds on the support surfaces. Hydrother-mal crystallization was then carried out in a synthesis solution with molar ratio of Al2O3:SiO2:Na2O:H2O=1:2:2:120 at 100 °C for 4 h. Effects of seeding conditions on preparation of hollow fiber NaA zeolite membranes were extensively investigated. Moreover, hollow fiber membrane modules with packing membrane areas of ca. 0.1 and 0.2 m2 were fabricated to separate ethanol/water mixture. It is found that the thickness of seed layer is obviously affected by seed suspension concentration, coating time and vacuum degree. Close-packing seed layer is required to obtain high-quality membranes. The optimized seeding conditions (seed suspension mass concentration of 0.5%–0.7%, coating time of 5 s and vacuum degree of 10 kPa) lead to dense NaA zeolite layer with a thickness of 6–8μm. Typically, an as-synthesized hollow fiber NaA zeolite membrane exhibits good pervaporation performance with a permeation flux of 7.02 kg·m−2·h−1 and separation factor N 10000 for sepa-ration of 90%(by mass) ethanol/water mixture at 75 °C. High reproducibility has been achieved for batch-scale production of hollow fiber NaA zeolite membranes by the hydrothermal synthesis approach.

  4. Inorganic porous hollow fiber membranes : with tunable small radial dimensions

    NARCIS (Netherlands)

    Luiten-Olieman, M.W.J.

    2012-01-01

    The objectives of this thesis are twofold. The first aim is to develop of robust coating procedures for thin supported films onto porous ceramic supports. The second aim is the development of a preparation methodology for high quality porous inorganic membranes, with large membrane surface area. A r

  5. Recovery of phenol from aqueous streams in hollow fiber modules.

    Science.gov (United States)

    Cichy, W; Szymanowski, J

    2002-05-01

    A setup with two parallel hollow-fiber modules was used to study the recovery of phenol from aqueous solutions. Cyanex 923, Amberlite LA-2, and trioctylamine (TOA) in aliphatic kerosene were used as carriers. A solution of 0.2 M NaOH was used for stripping. It was found that each of the studied carriers permitted the effective removal of phenol. Cyanex 923 showed the best performance, removing phenol in the shortest time and giving the highest fluxes and the highest mass-transfer coefficients. The maximum fluxes of phenol entering the receiving phase changed in the following ratio: Cyanex 923/Amberlite LA-2/TOA = 3.5/1.5/1. The mass-transfer coefficient in the extraction step changed in the same order: 34/5.2/1. The mass-transfer coefficients of the stripping step were 2-4 orders lower than in the extraction step and were comparable for each carrier: Cyanex 923/Amberlite LA-2/TOA = 1.1/0.7/1. Using Cyanex 923, only 5 min were needed to recover 99% of the pollutant from the aqueous stream, containing 0.5-2 g L(-1) phenol.

  6. Influence of nano-fiber membranes on the silver ions released from hollow fibers containing silver particles

    Directory of Open Access Journals (Sweden)

    Li Huigai

    2016-01-01

    Full Text Available Polyether sulfone was dissolved into dimethylacetamide with the concentration of 20% to prepare a uniform solution for fabrication of nanofiber membranes by bubble electrospinning technique. Morphologies of the nanofiber film were carried out with a scanning electron microscope. The influence on the silver ions escaped from hollow fiber loaded with silver particles was exerted by using different release liquid. The water molecular clusters obtained from the nanofiber membranes filter can slow down the release of silver ions. However, the effect of slowing was weakened with the time increasing. In the end, the trend of change is gradually consistent with the trend of release of silver ions in the deionized water.

  7. Molecularly Designed Stabilized Asymmetric Hollow Fiber Membranes for Aggressive Natural Gas Separation.

    Science.gov (United States)

    Liu, Gongping; Li, Nanwen; Miller, Stephen J; Kim, Danny; Yi, Shouliang; Labreche, Ying; Koros, William J

    2016-10-24

    New rigid polyimides with bulky CF3 groups were synthesized and engineered into high-performance hollow fiber membranes. The enhanced rotational barrier provided by properly positioned CF3 side groups prohibited fiber transition layer collapse during cross-linking, thereby greatly improving CO2 /CH4 separation performance compared to conventional materials for aggressive natural gas feeds. © 2016 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  8. Tri-bore PVDF hollow fibers with a super-hydrophobic coating for membrane distillation

    KAUST Repository

    Lu, Kang-Jia

    2016-04-26

    Membranes with good mechanical strength, high vapor flux and outstanding anti-wetting properties are essential for membrane distillation (MD) applications. In this work, porous polyvinylidene fluoride (PVDF) tri-bore hollow fiber membranes with super-hydrophobicity are developed to achieve these desired properties. The tri-bore hollow fiber offers better mechanical strength than the conventional single-bore fiber. To improve its anti-wetting properties, Teflon® AF 2400 is coated on the membrane surface. The effects of coating on membrane morphology, performance and anti-wetting properties have been thoroughly investigated. With an optimal coating condition (0.025 wt% of Teflon® AF 2400, 30 s), a super-hydrophobic surface with a contact angle of 151o is achieved. The resultant membrane shows an increase of 109% in liquid entry pressure (LEP) with a slight sacrifice of 21% in flux. Long term direct contact MD tests have confirmed that the Teflon® AF 2400 coated membrane has enhanced stability with an average flux of 21 kg m-2 h-1 and rejection of 99.99% at 60 °° C for desalination application.

  9. Green Modification of Outer Selective P84 Nanofiltration (NF) Hollow Fiber Membranes for Cadmium Removal

    KAUST Repository

    Gao, Jie

    2015-10-26

    Outer-selective thin-film composite (TFC) hollow fiber membranes are normally made from interfacial polymerization of m-phenylenediamine (MPD) and trimesoyl chloride (TMC). However, the removal of excess MPD solution and the large consumption of alkane solvents are their technical bottlenecks. In this study, green methods to prepare the outer selective TFC hollow fiber membranes were explored by firstly modifying the membrane substrate with polyethyleneimine (PEI) and then by water soluble small molecules such as glutaraldehyde (GA) and epichlorohydrin (ECH). Using P84 polyimide as the substrate, not only do these modifications decrease substrate\\'s pore size, but also vary surface charge by making the membranes less positively charged. As a result, the resultant membranes have higher rejections against salts such as Na2SO4, NaCl and MgSO4. The PEI and then GA modified membrane has the best separation performance with a NaCl rejection over 90% and a pure water permeability (PWP) of 1.74±0.01 Lm−2bar−1h−1. It also shows an impressive rejection to CdCl2 (94%) during long-term stability tests. The CdCl2 rejection remains higher than 90% at operating temperatures from 5 to 60 °C. This study may provide useful insights for green manufacturing of outer-selective nanofiltration (NF) hollow fiber membranes.

  10. Removal of volatile to semi-volatile organic contaminants from water using hollow fiber membrane contactors and catalytic destruction of the contaminants in the gas phase

    OpenAIRE

    Tarafder, Shamsul Abedin

    2007-01-01

    Abstract Chlorinated organic compounds and ether compounds are frequently found in groundwater and efficient treatment options are needed. In this study, the efficient transferal of the compounds from the water phase to the gas phase was studied followed by the catalytic treatment of the gas phase. For the removal of the organic contaminants from water, a microporous polypropylene hollow fiber membrane (HFM) module was operated under low strip gas flow to water flow ratios (_< 5:1). Rem...

  11. 225m Outdoor W-Band Radio-over-Fiber Link Using an Optical SFP+ Module

    DEFF Research Database (Denmark)

    Rommel, Simon; Rodríguez Páez, Juan Sebastián; Chorchos, Łukasz

    2016-01-01

    A W-band radio-over-fiber link based on a commercial SFP+ module is demonstrated, allowing easy integration into existing PON solutions. Without active laser control good RF frequency stability and 225m wireless distance are achieved...

  12. Nonlinear Pulse Compression and Reshaping Using Cross-Phase Modulation in a Dispersion-Shifted Fiber

    Institute of Scientific and Technical Information of China (English)

    S.; W.; Chan; K.; K.; Chow; C.; Shu

    2003-01-01

    Nonlinear pulse compression has been demonstrated by cross-phase modulation in a dispersion-shifted fiber. The output is obtained from filtering of the broadened optical spectrum and a pulse width reduction from 61 to 28 ps is achieved.

  13. Optical Fiber Lasers and All Solid-State Passively Modulated Microchip Lasers

    Institute of Scientific and Technical Information of China (English)

    Junewen; Chen; Pie-Yau; Chien; Yu-Ting; Lee

    2003-01-01

    Erbium fiber lasers of continuous mode outputs and of pulsed picosecond and sub-picosecond pulses train are reported. Compact all solid state passively modulated microchip lasers are also developed to the same degree.

  14. Impact of Spectral Filter on Phase Modulation Pulse in Fiber Front End System

    Institute of Scientific and Technical Information of China (English)

    LI Jing; JING Feng; WANG Jian-Jun; XU Dang-Peng; LIN Hong-Huan; GENG Yuan-Chao; LI Ming-Zhong; DENG Ying; ZHU Na; ZHANG Rui

    2011-01-01

    The transmission characteristics of phase modulation pulse transmitted through the filter in the power amplifier are investigated theoretically and experimentally. The narrow bandpass filter can induce large temporal modula-tion depth for the phase modulation pulse and induce double amplitude modulation(AM)if the frequency shift is lower than half bandwidth of the signal spectrum. We should choose a wider bandwidth filter to minimize the impact of the filter on the output pulse and suppress the amplified spontaneous emission(ASE) for the power fiber amplifier. These results are of benefit to the design of the fiber front end system.

  15. Study on the enrichment of Sulfur Hexafluoride in the tmosphere through polyimide hollow fiber membrane

    Directory of Open Access Journals (Sweden)

    Wang Weixian

    2016-01-01

    Full Text Available Sulfur hexafluoride is per molecule the strongest greenhouse gas know, the features have brought SF6 into the climatic impact discussion aimed at reduction of emissions. The separation effects of sulfur hexafluoride in the atmosphere are studied through polyimide hollow fiber membrane with different conditions on pressure drop, gas flow and temperature. The sulfur hexafluoride concentration increased with increased pressure drop of the membrane, increased temperature and decreased non-filtrate flow flux; the recovery of sulfur hexafluoride exceeds 93%, enrichment coefficient was 18.5; sulfur hexafluoride is not detected at the flux of the filtrate flow, which means sulfur hexafluoride is riddled by membrane. The results showed that polyimide hollow fiber membrane can effectively separate sulfur hexafluoride from mixed gas

  16. Combined organic-inorganic fouling of forward osmosis hollow fiber membranes.

    Science.gov (United States)

    Arkhangelsky, Elizabeth; Wicaksana, Filicia; Tang, Chuyang; Al-Rabiah, Abdulrahman A; Al-Zahrani, Saeed M; Wang, Rong

    2012-12-01

    This research focused on combined organic-inorganic fouling and cleaning studies of forward osmosis (FO) membranes. Various organic/inorganic model foulants such as sodium alginate, bovine serum albumin (BSA) and silica nanoparticles were applied to polyamide-polyethersulfone FO hollow fiber membranes fabricated in our laboratory. In order to understand all possible interactions, experiments were performed with a single foulant as well as combinations of foulants. Experimental results suggested that the degree of FO membrane fouling could be promoted by synergistic effect of organic foulants, the presence of divalent cations, low cross-flow velocity and high permeation drag force. The water flux of fouled FO hollow fibers could be fully restored by simple physical cleaning. It was also found that hydrodynamic regime played an important role in combined organic-inorganic fouling of FO membranes.

  17. Distributed MIMO Antenna Architecture for Wireless-over- Fiber Backhaul with Multicarrier Optical Phase Modulation

    DEFF Research Database (Denmark)

    Caballero Jambrina, Antonio; Wong, Shing-Wa; Zibar, Darko

    2011-01-01

    A novel optical phase-modulated wireless-over-fiber backhaul architecture for next generation cellular network is presented and experimentally demonstrated for high capacity wireless multicarrier uplink transmission on a single wavelength.......A novel optical phase-modulated wireless-over-fiber backhaul architecture for next generation cellular network is presented and experimentally demonstrated for high capacity wireless multicarrier uplink transmission on a single wavelength....

  18. Brillouin suppression in a fiber optical parametric amplifier by combining temperature distribution and phase modulation

    DEFF Research Database (Denmark)

    Lorenzen, Michael Rodas; Noordegraaf, Danny; Nielsen, Carsten Vandel

    2008-01-01

    We demonstrate an increased gain in optical parametric amplier through suppression of stimulated Brillouin scattering by applying a temperature distribution along the fiber resulting in a reduction of the required phase modulation.......We demonstrate an increased gain in optical parametric amplier through suppression of stimulated Brillouin scattering by applying a temperature distribution along the fiber resulting in a reduction of the required phase modulation....

  19. Hydrogen separation from multicomponent gas mixtures containing CO, N2 and CO2 using Matrimid asymmetric hollow fiber membranes

    NARCIS (Netherlands)

    David, Oana C.; Gorri, Daniel; Nijmeijer, Dorothea C.; Ortiz, Inmaculada; Urtiaga, Ane

    2012-01-01

    The application of hollow fiber membranes for the separation of industrial gas mixtures relies on the correct characterization of the permeation of the involved gaseous components through the hollow fiber membranes. Thus, this study is focused on the characterization of the permeation through

  20. Morphological architecture of dual-layer hollow fiber for membrane distillation with higher desalination performance.

    Science.gov (United States)

    Wang, Peng; Teoh, May May; Chung, Tai-Shung

    2011-11-01

    A new strategy to enhance the desalination performance of polyvinylidene fluoride (PVDF) hollow fiber membrane for membrane distillation (MD) via architecture of morphological characteristics is explored in this study. It is proposed that a dual-layer hollow fiber consisting of a fully finger-like macrovoid inner-layer and a sponge-like outer-layer may effectively enhance the permeation flux while maintaining the wetting resistance. Dual-layer fibers with the proposed morphology have been fabricated by the dry-jet wet spinning process via careful choice of dopes composition and coagulation conditions. In addition to high energy efficiency (EE) of 94%, a superior flux of 98.6 L m(-2) h(-1) is obtained during the direct contact membrane distillation (DCMD) desalination experiments. Moreover, the liquid entry pressure (LEP) and long-term DCMD performance test show high wetting resistance and long-term stability. Mathematical modeling has been conducted to investigate the membrane mass transfer properties in terms of temperature profile and apparent diffusivity of the membranes. It is concluded that the enhancement in permeation flux arises from the coupling effect of two mechanisms; namely, a higher driving force and a lower mass transfer resistance, while the later is the major contribution. This work provides an insight on MD fundamentals and strategy to tailor making ideal membranes for DCMD application in desalination industry. Copyright © 2011 Elsevier Ltd. All rights reserved.

  1. Darcy permeability of hollow fiber membrane bundles made from Membrana® Polymethylpentene (PMP) fibers used in respiratory assist devices

    Science.gov (United States)

    Madhani, Shalv. P.; D’Aloiso, Brandon. D.; Frankowski, Brian.; Federspiel, William. J.

    2016-01-01

    Hollow fiber membranes (HFMs) are used in blood oxygenators for cardiopulmonary bypass or in next generation artificial lungs. Flow analyses of these devices is typically done using computational fluid dynamics (CFD) modeling HFM bundles as porous media, using a Darcy permeability coefficient estimated from the Blake – Kozeny (BK) equation to account for viscous drag from fibers. We recently published how well this approach can predict Darcy permeability for fiber bundles made from polypropylene HFMs, showing the prediction can be significantly improved using an experimentally derived correlation between the BK constant (A) and bundle porosity (ε). In this study, we assessed how well our correlation for A worked for predicting the Darcy permeability of fiber bundles made from Membrana® polymethylpentene (PMP) HFMs, which are increasingly being used clinically. Swatches in the porosity range of 0.4 to 0.8 were assessed in which sheets of fiber were stacked in parallel, perpendicular and angled configurations. Our previously published correlation predicted Darcy within ±8%. A new correlation based on current and past measured permeability was determined: A=497ε-103; using this correlation measured Darcy permeability was within ±6%. This correlation varied from 8% to −3.5% of our prior correlation over the tested porosity range. PMID:26809086

  2. Darcy Permeability of Hollow Fiber Membrane Bundles Made from Membrana Polymethylpentene Fibers Used in Respiratory Assist Devices.

    Science.gov (United States)

    Madhani, Shalv P; D'Aloiso, Brandon D; Frankowski, Brian; Federspiel, William J

    2016-01-01

    Hollow fiber membranes (HFMs) are used in blood oxygenators for cardiopulmonary bypass or in next generation artificial lungs. Flow analyses of these devices is typically done using computational fluid dynamics (CFD) modeling HFM bundles as porous media, using a Darcy permeability coefficient estimated from the Blake-Kozeny (BK) equation to account for viscous drag from fibers. We recently published how well this approach can predict Darcy permeability for fiber bundles made from polypropylene HFMs, showing the prediction can be significantly improved using an experimentally derived correlation between the BK constant (A) and bundle porosity (ε). In this study, we assessed how well our correlation for A worked for predicting the Darcy permeability of fiber bundles made from Membrana polymethylpentene (PMP) HFMs, which are increasingly being used clinically. Swatches in the porosity range of 0.4 to 0.8 were assessed in which sheets of fiber were stacked in parallel, perpendicular, and angled configurations. Our previously published correlation predicted Darcy within ±8%. A new correlation based on current and past measured permeability was determined: A = 497ε - 103; using this correlation measured Darcy permeability was within ±6%. This correlation varied from 8% to -3.5% of our prior correlation over the tested porosity range.

  3. RADIO OVER FIBER TECHNOLOGY USING ELECTRO-ABSORPTION MODULATION

    Directory of Open Access Journals (Sweden)

    SAURABH R. PRASAD

    2010-10-01

    Full Text Available The demand for bandwidth is increasing vigorously. Thus wired network is using fiber optic telephone line instead of coaxial cable. The concept of Fiber to the Home (FTTH is really coming into picture. Few countries like Japan, Korea etc are leading in this technology. But now the major challenge is how to provide the high speed internet connection wirelessly. Thus the change is to integrate the wireless and optical fiber communication.

  4. Ultem®/ZIF-8 mixed matrix hollow fiber membranes for CO2/N2 separations

    KAUST Repository

    Dai, Ying

    2012-05-01

    Organic-inorganic hybrid (mixed matrix) membranes can potentially extend the separation performance of traditional polymeric materials while maintaining processing convenience. Although many dense films studies have been reported, there have been few reported cases of these materials being successfully extended to asymmetric hollow fibers. In this work we report the first successful production of mixed matrix asymmetric hollow fiber membranes containing metal-organic-framework (MOF) ZIF-8 fillers. Specifically, we have incorporated ZIF-8 into a polyetherimide (Ultem ® 1000) matrix and produced dual-layer asymmetric hollow fiber membranes via the dry jet-wet quench method. The outer separating layer of these composite fibers contains 13wt% (17vol%) of ZIF-8 filler. These membranes have been tested over a range of temperatures and pressures for a variety of gas pairs. An increase in separation performance for the CO 2/N 2 gas pairs was observed for both pure gas and mixed gas feeds. © 2012 Elsevier B.V.

  5. Development and characterization of poly(ε-caprolactone) hollow fiber membranes for vascular tissue engineering

    NARCIS (Netherlands)

    Diban-Ibrahim Gomez, Nazely; Haimi, Suvi; Bolhuis-Versteeg, Lydia A.M.; Da Silva Teixeira, Sandra; Miettinen, S.; Poot, Andreas A.; Grijpma, Dirk W.; Stamatialis, Dimitrios

    2013-01-01

    The fabrication of tissue-engineered scaffolds for small-caliber blood vessels still remains a challenge. In the present work, we prepared poly(ε-caprolactone) (PCL) hollow fiber (HF) membranes, suitable for small-diameter blood vessel regeneration, by a phase separation spinning technique. The diff

  6. Ultem((R))/ZIF-8 mixed matrix hollow fiber membranes for CO2/N-2 separations

    Energy Technology Data Exchange (ETDEWEB)

    Dai, Y; Johnson, JR; Karvan, O; Sholl, DS; Koros, WJ

    2012-05-15

    Organic-inorganic hybrid (mixed matrix) membranes can potentially extend the separation performance of traditional polymeric materials while maintaining processing convenience. Although many dense films studies have been reported, there have been few reported cases of these materials being successfully extended to asymmetric hollow fibers. In this work we report the first successful production of mixed matrix asymmetric hollow fiber membranes containing metal-organic-framework (MOF) ZIF-8 fillers. Specifically, we have incorporated ZIF-8 into a polyetherimide (Ultem((R)) 1000) matrix and produced dual-layer asymmetric hollow fiber membranes via the dry jet-wet quench method. The outer separating layer of these composite fibers contains 13 wt% (17 vol%) of ZIF-8 filler. These membranes have been tested over a range of temperatures and pressures for a variety of gas pairs. An increase in separation performance for the CO2/N-2 gas pairs was observed for both pure gas and mixed gas feeds. (C) 2012 Elsevier B.V. All rights reserved.

  7. Characterization of polyethersulfone-polyimide hollow fiber membranes by atomic force microscopy and contact angle goniometery

    NARCIS (Netherlands)

    Khulbe, K.C.; Feng, C.; Matsuura, T.; Kapantaidakis, G.; Wessling, Matthias; Koops, G.H.

    2003-01-01

    Asymmetric blend polyethersulfone-polyimide (PES-PI) hollow fiber membranes prepared at different air gap and used for gas separation are characterized by atomic force microscopy (inside and out side surfaces) and by measuring the contact angle of out side surface. The outer surface was entirely

  8. Mach-Zehnder modulator modulated radio-over-fiber transmission system using dual wavelength linearization

    Science.gov (United States)

    Zhu, Ran; Hui, Ming; Shen, Dongya; Zhang, Xiupu

    2017-02-01

    In this paper, dual wavelength linearization (DWL) technique is studied to suppress odd and even order nonlinearities simultaneously in a Mach-Zehnder modulator (MZM) modulated radio-over-fiber (RoF) transmission system. A theoretical model is given to analyze the DWL employed for MZM. In a single-tone test, the suppressions of the second order harmonic distortion (HD2) and third order harmonic distortion (HD3) at the same time are experimentally verified at different bias voltages of the MZM. The measured spurious-free dynamic ranges (SFDRs) with respect to the HD2 and HD3 are improved simultaneously compared to using a single laser. The output P1 dB is also improved by the DWL technique. Moreover, a WiFi signal is transmitted in the RoF system to test the linearization for broadband signal. The result shows that more than 1 dB improvement of the error vector magnitude (EVM) is obtained by the DWL technique.

  9. A 60GHz RoF(radio-over-fiber) transmission system based on PM modulator

    Science.gov (United States)

    Wang, Xin; Liu, Yi; Wang, Wen-Ting

    2016-11-01

    As one of the most important applications of microwave photonic ROF (Radio over Fiber) system which combines the advantages of optical communication and wireless communication is a good candidate for broadband mobile Communication In this paper, we built and simulation a 60GHz RoF(Radio-over-Fiber) transmission system based on PM modulator. First, we introduce the PM-IM(Phase modulation to intensity modulation) modulation mechanisms by the breaking the phase balanced approach. This method solves the problem that the constant envelope (phase modulation signal) generated by the phase modulator can not be directly detected by a photo detector. A standard single-mode fiber (SMF) is connected input to the F-P(Fabry-Perot) optical filter, which is to achieve the PM-IM modulation conversion by changing the wavelength of the laser or the frequency of the modulation factor of the F-P optical filter to adapt to different fiber lengths and the signal transmission rate. These two methods which changing the phase relationship between the optical carrier and the optical side band can realize the ideal phase transition to obtain efficient and low loss modulation conversion. Finally, the simulation results show that different fiber lengths and the signal transmission rate configuration of different wavelength of the laser or the frequency of the modulation factor of the F-P optical filter, the BER performance and the eye diagram of the 60GHz RoF transmission system signals have been improved based on these PM-IM modulation methods.

  10. Carbon molecular sieve membranes prepared from porous fiber precursor

    NARCIS (Netherlands)

    Barsema, J.N.; van der Vegt, N.F.A.; Koops, G.H.; Wessling, Matthias

    2002-01-01

    Carbon molecular sieve (CMS) membranes are usually prepared from dense polymeric precursors that already show intrinsic gas separation properties. The rationale behind this approach is that the occurrence of any kind of initial porosity will deteriorate the final CMS performance. We will show that

  11. Carbon molecular sieve membranes prepared from porous fiber precursor

    NARCIS (Netherlands)

    Barsema, Jonathan N.; Vegt, van der N.F.A.; Koops, G.H.; Wessling, M.

    2002-01-01

    Carbon molecular sieve (CMS) membranes are usually prepared from dense polymeric precursors that already show intrinsic gas separation properties. The rationale behind this approach is that the occurrence of any kind of initial porosity will deteriorate the final CMS performance. We will show that i

  12. Modulation Instability in Non-Kerr-like Optical Fibers near the Zero Dispersion Point

    Institute of Scientific and Technical Information of China (English)

    LIU Xiumin; ZHANG Xiaoguang; LIN Ning; ZHANG Tao; YANG Bojun

    2000-01-01

    Modulation instability (MI) in non-Kerr-like optical fiber near the zero dispersion point is analyzed. Taking into account the fourth order dispersion, new regions of MI are found. The action of the self-steepening is not the same for each region of MI and critical modulation frequency.

  13. Locking of self-oscillation frequency by pump modulation in an erbium-doped fiber laser

    Science.gov (United States)

    Pisarchik, A. N.; Barmenkov, Yu. O.

    2005-10-01

    Frequency locking of self-oscillations in a diode-pumped erbium-doped fiber laser by external modulation of the diode current is studied experimentally. The coexistence of locking and unlocking regimes is detected. The condition for onset of the bistability and dependences of the frequency detuning on the modulation frequency and amplitude are established. Transitions to torus-chaos are also demonstrated.

  14. The Experimental Study on Acousto-optic Modulation Based on Single-mode Fiber Fused Coupler

    Institute of Scientific and Technical Information of China (English)

    Liu Guoxiang; Hu Li; Ye Kunzhen; Lin Weigan

    2002-01-01

    In-line acoustic-optic (AO) modulation experiments were demonstrated based on the acoustic-optic effect in optical fiber fused taper couplers.About 73%,64%,and 61% modulation have been achieved at frequencies of 0.169 MHz,0.367 MHz and 0.521 MHz with an electrical driving power less than 10 mW,respectively.

  15. MORPHOLOGIES AND GAS SEPARATION PROPERTIES OF MELT-SPUN ASYMMETRIC POLY(4-METHYL-1-PENTENE) HOLLOW FIBER MEMBRANES

    Institute of Scientific and Technical Information of China (English)

    Jian-li Wang; Zhi-kang Xu; You-yi Xu

    2003-01-01

    Poly(4-methyl-1-pentene) (PMP) hollow fiber membranes were prepared by the melt-spun and cold-stretch(MSCS) method. Scanning electronic microscopy (SEM) was used to characterize the section and surface structures of the membranes with special asymmetric structure. The preliminary results of gas permeation measurements indicated that the resultant hollow fiber membranes have the potential ability for oxygen/nitrogen separation.

  16. Bamboo shoot fiber prevents obesity in mice by modulating the gut microbiota

    Science.gov (United States)

    Li, Xiufen; Guo, Juan; Ji, Kailong; Zhang, Ping

    2016-01-01

    Dietary fiber has been shown to prevent high-fat diet induced obesity through modulating the gut microbiota; however, quality difference in fiber type is largely unknown. We performed a 6 week study on C57BL/6J mice fed a macronutrient matched high-fat diet with different fiber types including cellulose (HFC), bamboo shoot fiber (HFBS) and several other commonly consumed fibers. Our results showed that the HFBS group exhibited the lowest weight gain among all diet groups and had improved lipid profiles and glycemic control compared with the HFC group. As revealed by 16S rRNA gene sequencing, loss of diversity in the gut microbiota induced by the HFC diet was largely prevented by the HFBS diet. Moreover, compared with the HFC diet, the HFBS diet resulted in markedly increased relative abundance of Bacteroidetes and strong inhibition of Verrucomicrobia, two divisions strongly correlated with body weight. In conclusion, the present study provides evidence of a quality difference among different types of dietary fibers and shows that bamboo shoot fiber is the most effective in suppressing high-fat diet induced obesity. Our findings indicate that bamboo shoot fiber is a potential prebiotic fiber which modulates the gut microbiota and improves host metabolism. PMID:27599699

  17. Modeling and parametric analysis of hollow fiber membrane system for carbon capture from multicomponent flue gas

    KAUST Repository

    Khalilpour, Rajab

    2011-08-12

    The modeling and optimal design/operation of gas membranes for postcombustion carbon capture (PCC) is presented. A systematic methodology is presented for analysis of membrane systems considering multicomponent flue gas with CO 2 as target component. Simplifying assumptions is avoided by namely multicomponent flue gas represented by CO 2/N 2 binary mixture or considering the co/countercurrent flow pattern of hollow-fiber membrane system as mixed flow. Optimal regions of flue gas pressures and membrane area were found within which a technoeconomical process system design could be carried out. High selectivity was found to not necessarily have notable impact on PCC membrane performance, rather, a medium selectivity combined with medium or high permeance could be more advantageous. © 2011 American Institute of Chemical Engineers (AIChE).

  18. An analog modulation and demodulation method employing LVDT signal conditioner for fiber-optic interferometric sensors

    Science.gov (United States)

    Zhou, Kejiang; Rao, Qi; Zhang, Minjie; Hu, Keke; Ruan, Yefeng

    2017-09-01

    An analog method to modulate and demodulate fiber-optic interferometric sensors employing a linear variable differential transformer signal conditioner to generate sine modulation wave and demodulate phase-modulated signal from the photodetector’s output is presented in this letter. No external lock-in amplifiers or digital components are used in this design. All the necessary components for signal processing are integrated in a single analog electronic microchip AD698, which reduces the system’s complexity significantly. After implementation on an interferometric fiber-optic gyroscope as an example, this method demonstrates a bias stability of 0.063 deg h-1 (i.e. 0.220 µrad).

  19. Theoretical model of the modulation transfer function for fiber optic taper

    Science.gov (United States)

    Wang, Yaoxiang; Tian, Weijian; Bin, XiangLi

    2005-02-01

    Fiber optic taper has been used more and more widely as a relay optical component in the integrated taper assembly image intensified sensors for military and medical imaging application. In this paper, the transmission characteristic of energy in the taper is analyzed, and following the generalized definition of the modulation transfer function for sampled imaging system, a spatial averaged impulse response and a corresponding MTF component that are inherent in the sampling process of taper are deduced, and the mathematical model for evaluating the modulation transfer function of fiber optic taper is built. Finally, the dynamic and static modulation transfer function curves simulated by computer have been exhibited.

  20. A Novel Inter Core-Cladding Lithium Niobate Thin Film Coated Fiber Modulator/Sensor

    Science.gov (United States)

    Jamison, Tracee L.; Komriech, Phillip; Yu, Chung

    2004-01-01

    A fiber modulator/sensor has been fabricated by depositing a lithium niobate sol-gel thin film between the core and cladding of a fiber preform. The preform is then drawn into 125 micron fiber. The proposed design of lithium niobate cylinder fibers can enhance the existing methodology for detecting sound waves under water utilizing the acoustooptic properties of lithium niobate. Upon application of a stress or strain, light propagating inside the core, according to the principle of total internal reflection, escapes, into the cladding because of the photoelastic boundary layer of lithium niobate. Test results of the lithium niobate fiber reveal a reduction in the 1550 nm, 4mW source with applied tension. The source power from an ordinary quartz fiber under the same stress condition remained invariant to applied tension.

  1. Evaluation of dialyzer jacket structure and hollow-fiber dialysis membranes to achieve high dialysis performance.

    Science.gov (United States)

    Hirano, Ayaka; Yamamoto, Ken-ichiro; Matsuda, Masato; Ogawa, Takehito; Yakushiji, Taiji; Miyasaka, Takehiro; Sakai, Kiyotaka

    2011-02-01

    The objective of this study was to determine the optimum dialyzer jacket structure and hollow-fiber dialysis membrane, both of which are indispensable factors for achieving high dialysis performance, by clarifying the relationship between the dialysis performance and the flow of dialysate and blood in a hollow-fiber dialyzer. We evaluated the clearance, dialysate, and blood flow for four commercially available hollow-fiber dialyzers, namely, the APS-15S, APS-15SA, TS-1.6UL, and CX-1.6U. To evaluate dialysate and blood flow, we measured the residence-time distribution of dialysate and blood flow of these dialyzers by the pulse-response method. We also determined the clearances of urea, creatinine, vitamin B(12), and lysozyme to evaluate the dialysis performance of these dialyzers. While the baffle and taper structures allow effective supply of dialysate into the dialyzer jacket, the hollow-fiber shape, inner diameter, and packing density significantly influence the dialysate flow. In dialyzers with long taper-holding slits, the slit area is a key design parameter for achieving optimum dialysate flow. Similarly, the blood flow is significantly influenced by the structure of the inflowing and outflowing blood ports at the header of a dialyzer, and the shape and inner diameter of the hollow fibers. Hollow fibers with smaller inner diameters cause an increase in blood pressure, which causes blood to enter the hollow fibers more easily. The hollow-fiber shape hardly affects the blood flow. While improved dialysate and blood flow cause higher clearance of low molecular-weight substances, higher membrane area and pure-water permeability accelerate internal filtration, thereby causing an increase in the clearance of large molecular-weight substances. © 2010 The Authors. Therapeutic Apheresis and Dialysis © 2010 International Society for Apheresis.

  2. Chemistry in a spinneret - On the interplay of crosslinking and phase inversion during spinning of novel hollow fiber membranes

    NARCIS (Netherlands)

    Kopec, K.K.; Dutczak, S.M.; Wessling, Matthias; Stamatialis, Dimitrios

    2011-01-01

    This work explores a new method of simultaneous membrane formation and chemical modification in a spinning process for fabricating asymmetric composite hollow fiber membranes. This method is based on controlled crosslinking reaction between the membrane forming polyimide P84 and the chemically

  3. Improved performance of gravity-driven membrane filtration for seawater pretreatment: Implications of membrane module configuration.

    Science.gov (United States)

    Wu, Bing; Christen, Tino; Tan, Hwee Sin; Hochstrasser, Florian; Suwarno, Stanislaus Raditya; Liu, Xin; Chong, Tzyy Haur; Burkhardt, Michael; Pronk, Wouter; Fane, Anthony G

    2017-05-01

    As a low energy and chemical free process, gravity-driven membrane (GDM) filtration has shown a potential for seawater pretreatment in our previous studies. In this study, a pilot submerged GDM reactor (effective volume of 720 L) was operated over 250 days and the permeate flux stabilized at 18.6 ± 1.4 L/m(2)h at a hydrostatic pressure of 40 mbar. This flux was higher than those in the lab-scale GDM reactor (16.3 ± 0.2 L/m(2)h; effective volume of 8.4 L) and in the filtration cell system (2.7 ± 0.6 L/m(2)h; feed side volume of 0.0046 L) when the same flat sheet membrane was used. Interestingly, when the filtration cell was submerged into the GDM reactor, the flux (17.2 L/m(2)h) was comparable to the submerged membrane module. Analysis of cake layer morphology and foulant properties indicated that a thicker but more porous cake layer with less accumulation of organic substances (biopolymers and humics) contributed to the improved permeate flux. This phenomenon was possibly associated with longer residence time of organic substances and sufficient space for the growth, predation, and movement of the eukaryotes in the GDM reactor. In addition, the permeate flux of the submerged hollow fibre membrane increased with decreasing packing density. It is thought that the movement of large-sized eukaryotes could be limited when the space between hollow fibres was reduced. In terms of pretreatment, the GDM systems effectively removed turbidity, viable cells, and transparent exopolymer particles from the feed seawater. Importantly, extending the reactor operation time produced a permeate with less assimilable organic carbon and biopolymers. Thus, the superior quality of the GDM permeate has the potential to alleviate subsequent reverse osmosis membrane fouling for seawater treatment. Copyright © 2017 Elsevier Ltd. All rights reserved.

  4. Directly-Modulated VCSELs for 2x2 MIMO-OFDM Radio over Fiber in WDM-PON

    DEFF Research Database (Denmark)

    Binti Othman, Maisara; Deng, Lei; Pang, Xiaodan;

    2011-01-01

    We demonstrate directly- modulated VCSELs supporting 2x2 MIMO-OFDM 5.6-GHz radio over fiber signaling over 20-km WDM-PON. Error-free signal demodulation of 64-subcarrier 4-QAM signals modulated at 198.5-Mb/s is achieved after fiber and 2-m indoor wireless transmission.......We demonstrate directly- modulated VCSELs supporting 2x2 MIMO-OFDM 5.6-GHz radio over fiber signaling over 20-km WDM-PON. Error-free signal demodulation of 64-subcarrier 4-QAM signals modulated at 198.5-Mb/s is achieved after fiber and 2-m indoor wireless transmission....

  5. Hollow Fiber Membrane Contactors for CO2 Capture: Modeling and Up-Scaling to CO2 Capture for an 800 MWe Coal Power Station

    Directory of Open Access Journals (Sweden)

    Kimball Erin

    2014-11-01

    Full Text Available A techno-economic analysis was completed to compare the use of Hollow Fiber Membrane Modules (HFMM with the more conventional structured packing columns as the absorber in amine-based CO2 capture systems for power plants. In order to simulate the operation of industrial scale HFMM systems, a two-dimensional model was developed and validated based on results of a laboratory scale HFMM. After successful experiments and validation of the model, a pilot scale HFMM was constructed and simulated with the same model. The results of the simulations, from both sizes of HFMM, were used to assess the feasibility of further up-scaling to a HFMM system to capture the CO2 from an 800 MWe power plant. The system requirements – membrane fiber length, total contact surface area, and module volume – were determined from simulations and used for an economic comparison with structured packing columns. Results showed that a significant cost reduction of at least 50% is required to make HFMM competitive with structured packing columns. Several factors for the design of industrial scale HFMM require further investigation, such as the optimal aspect ratio (module length/diameter, membrane lifetime, and casing material and shape, in addition to the need to reduce the overall cost. However, HFMM were also shown to have the advantages of having a higher contact surface area per unit volume and modular scale-up, key factors for applications requiring limited footprints or flexibility in configuration.

  6. Hollow Fiber Membrane Contactors for Post-Combustion CO2 Capture: A Scale-Up Study from Laboratory to Pilot Plant

    Directory of Open Access Journals (Sweden)

    Chabanon E.

    2014-11-01

    Full Text Available Membrane contactors have been proposed for decades as a way to achieve intensified mass transfer processes. Post-combustion CO2 capture by absorption into a chemical solvent is one of the currently most intensively investigated topics in this area. Numerous studies have already been reported, unfortunately almost systematically on small, laboratory scale, modules. Given the level of flue gas flow rates which have to be treated for carbon capture applications, a consistent scale-up methodology is obviously needed for a rigorous engineering design. In this study, the possibilities and limitations of scale-up strategies for membrane contactors have been explored and will be discussed. Experiments (CO2 absorption from a gas mixture in a 30%wt MEA aqueous solution have been performed both on mini-modules and at pilot scale (10 m2 membrane contactor module based on PTFE hollow fibers. The results have been modelled utilizing a resistance in series approach. The only adjustable parameter is in fitting the simulations to experimental data is the membrane mass transfer coefficient (km, which logically plays a key role. The difficulties and uncertainties associated with scaleup computations from lab scale to pilot scale modules, with a particular emphasis on the km value, are presented and critically discussed.

  7. Preparation of [11C]formaldehyde using a hollow fiber membrane bioreactor.

    Science.gov (United States)

    Hughes, J A; Jay, M

    1995-01-01

    A bioreactor consisting of the enzymes alcohol oxidase and catalase immobilized onto a hollow fiber membrane was used to convert [11C]methanol to [11C]formaldehyde. Using an alcohol oxidase:catalase ratio of 1:500 U, conversion yields of 90-95% were obtained allowing the production of up to 7400 MBq (200 mCi) of [11C]formaldehyde in 5 min. The hollow fiber bioreactor allowed for a convenient, rapid synthesis with yields significantly higher than the standard chemical procedures, has demonstrable advantages over glass bead immobilized systems (primarily due to convective flow), and was amenable to hot cell conditions.

  8. Oxygen Transfer Model for a Flow-Through Hollow-Fiber Membrane Biofilm Reactor

    DEFF Research Database (Denmark)

    Gilmore, K. R.; Little, J. C.; Smets, Barth F.

    2009-01-01

    A mechanistic oxygen transfer model was developed and applied to a flow-through hollow-fiber membrane-aerated biofilm reactor. Model results are compared to conventional clean water test results as well as performance data obtained when an actively nitrifying biofilm was present on the fibers....... With the biofilm present, oxygen transfer efficiencies between 30 and 55% were calculated from the measured data including the outlet gas oxygen concentration, ammonia consumption stoichiometry, and oxidized nitrogen production stoichiometry, all of which were in reasonable agreement. The mechanistic model...

  9. A validated CFD model to predict O₂ and CO₂ transfer within hollow fiber membrane oxygenators.

    Science.gov (United States)

    Hormes, Marcus; Borchardt, Ralf; Mager, Ilona; Rode, Thomas Schmitz; Behr, Marek; Steinseifer, Ulrich

    2011-03-01

    Hollow fiber oxygenators provide gas exchange to and from the blood during heart surgery or lung recovery. Minimal fiber surface area and optimal gas exchange rate may be achieved by optimization of hollow fiber shape and orientation (1). In this study, a modified CFD model is developed and validated with a specially developed micro membrane oxygenator (MicroMox). The MicroMox was designed in such a way that fiber arrangement and bundle geometry are highly reproducible and potential flow channeling is avoided, which is important for the validation. Its small size (V(Fluid)=0.04 mL) allows the simulation of the entire bundle of 120 fibers. A non-Newtonian blood model was used as simulation fluid. Physical solubility and chemical bond of O₂ and CO₂ in blood was represented by the numerical model. Constant oxygen partial pressure at the pores of the fibers and a steady state flow field was used to calculate the mass transport. In order to resolve the entire MicroMox fiber bundle, the mass transport was simulated for symmetric geometry sections in flow direction. In vitro validation was achieved by measurements of the gas transfer rates of the MicroMox. All measurements were performed according to DIN EN 12022 (2) using porcine blood. The numerical simulation of the mass transfer showed good agreement with the experimental data for different mass flows and constant inlet partial pressures. Good agreement could be achieved for two different fiber configurations. Thus, it was possible to establish a validated model for the prediction of gas exchange in hollow fiber oxygenators.

  10. Impacts of Coagulation Pretreatment on MF Filtration and a Comparative Study of Different Membrane Module Types

    Institute of Scientific and Technical Information of China (English)

    LIU Qi-feng; Kim Seung-hyun; Yun Jong-sup; Moon Seong-yong

    2006-01-01

    Changes in the regulatory requirements and the forthcoming Disinfectant/Disinfection By-Products (D/DBP)Rule will require that drinking water treatment facilities be operated to achieve maximum removals of particles and disinfectant tolerant microorganisms as well as natural organic matter (NOM). For drinking water production, the use of membrane filtration processes such as microfiltration and ultrafiltration (MF/UF) alone to satisfy the turbidity, particle and microorganism removal a requirement of the surface water treatment regulation (SWTR) is not enough. MF/UF treatment processes can achieve only nominal (10 percent) removal of disinfection by-products (DBP) precursors (James, et al., 1995). On the other hand, too fast fouling can make the filtration processes more difficult to carry on. To solve these problems, many authors have been interested in installing coagulation pretreatment before membrane filtration to improve membrane performance. However, previous studies reported conflicting results. Some supported the effectiveness of coagulation pretreatment, while others contended that coagulation aggravated membrane performance. This research aims to identify the effects of coagulation pretreatment on membrane filtration through a pilot study using PVDF membrane in combination with analyzing the rationale of coagulation. Another objective of this research was to evaluate the different impacts on membrane performance of using different membrane modules (the submerged module and pressured module). The results showed that coagulation pretreatment greatly improved the membrane performance, extending the filtration time as well as reducing the permeated organic level, and that the submerged module is much more efficient than the pressured module.

  11. Preparation and Preliminary Dialysis Performance Research of Polyvinylidene Fluoride Hollow Fiber Membranes

    Directory of Open Access Journals (Sweden)

    Qinglei Zhang

    2015-03-01

    Full Text Available In this study, the separation properties of Polyvinylidene fluoride (PVDF hollow fiber hemodialysis membranes were improved by optimizing membrane morphology and structure. The results showed that the PVDF membrane had better mechanical and separation properties than Fresenius Polysulfone High-Flux (F60S membrane. The PVDF membrane tensile stress at break, tensile elongation and bursting pressure were 11.3 MPa, 395% and 0.625 MPa, respectively. Ultrafiltration (UF flux of pure water reached 108.2 L∙h−1∙m−2 and rejection of Albumin from bovine serum was 82.3%. The PVDF dialyzers were prepared by centrifugal casting. The influences of membrane area and simulate fluid flow rate on dialysis performance were investigated. The results showed that the clearance rate of urea and Lysozyme (LZM were improved with increasing membrane area and fluid flow rate while the rejection of albumin from bovine serum (BSA had little influence. The high-flux PVDF dialyzer UF coefficient reached 62.6 mL/h/mmHg. The PVDF dialyzer with membrane area 0.69 m2 has the highest clearance rate to LZM and urea. The clearance rate of LZM was 66.8% and urea was 87.7%.

  12. Fiber intake modulates the association of alcohol intake with breast cancer

    DEFF Research Database (Denmark)

    Romieu, Isabelle; Ferrari, Pietro; Chajès, Veronique;

    2016-01-01

    fiber as a modifying factor of the association of alcohol and breast cancer using data from the European Prospective Investigation into Cancer and Nutrition (EPIC). This study included 334,850 women aged 35-70 years at baseline enrolled in the ten countries of the EPIC study and followed up for 11...... computed. During 3,670,439 person-years, 11,576 incident breast cancer cases were diagnosed. For subjects with low intake of fiber (24.2 g/day) the risk of BC was 1.02 (0.......99-1.05) (test for interaction p=0.011). This modulating effect was stronger for fiber from vegetables. Our results suggest that fiber intake may modulate the positive association of alcohol intake and BC. This article is protected by copyright. All rights reserved. © 2014 Wiley Periodicals, Inc....

  13. Active mode-locking via pump modulation in a Tm-doped fiber laser

    Directory of Open Access Journals (Sweden)

    Yu Wang

    2016-10-01

    Full Text Available We propose and experimentally realize a new class of actively mode-locking technique using pump modulation for rare-earth doped fiber lasers. A Tm-doped fiber laser at 2 μm is mode-locked using the proposed active mode-locking via pump modulation technique. Low-threshold continuous-wave mode-locking is achieved with a transform-limited pulse width of 4.4 ps, a spectral bandwidth of 0.9 nm, and a repetition rate of 12.9 MHz. Second-harmonic mode-locking is also demonstrated by simply driving the pump current at an appropriate frequency. More importantly, we believe that this technique can be applied to mode-lock other rare-earth doped fiber laser systems such as erbium- and ytterbium-doped fiber lasers.

  14. Synchronization and Coherent Combining of Two Pulsed Fiber Ring Lasers Based on Direct Phase Modulation

    Institute of Scientific and Technical Information of China (English)

    WANG Xiao-Lin; ZHOU Pu; MA Hao-Tong; CHEN Zi-Lun; LI Xiao; XU Xiao-Jun; LIU Ze-Jin

    2009-01-01

    We demonstrate a scalable architecture for coherent combining of pulsed fiber ring lasers based on mutual injection and direct phase modulation. By direct phase modulation in the common arm of two ring lasers, synchronous pulsed lasers can be generated and coherent combining of the two synchronous lasers is obtained. Two pulsed fiber ring lasers are coherently combined with 0.55 μJ pulse energy and 10μs pulse duration at a repetition rate of 27.5 kHz. Experimental results show that the two fiber ring lasers are phase locked with an invariable phase difference of π and have good temporal synchronization and spatial coherence. The combining efficiency of the two pulsed fiber laser reaches 90% and the fringe contrast is larger than 40%. Neither active phase control nor polarization control is used in our experiment and this method can be extended to combine more beams and higher repetition rate scaling up to higher power.

  15. Toluene impurity effects on CO2 separation using a hollow fiber membrane for natural gas

    KAUST Repository

    Omole, Imona C.

    2011-03-01

    The performance of defect-free cross-linkable polyimide asymmetric hollow fiber membranes was characterized using an aggressive feed stream containing up to 1000ppm toluene. The membrane was shown to be stable against toluene-induced plasticization compared with analogs made from Matrimid®, a commercial polyimide. Permeation and sorption analysis suggest that the introduction of toluene vapors in the feed subjects the membrane to antiplasticization, as the permeance decreases significantly (to less than 30%) under the most aggressive conditions tested. Separation efficiencies reflected by permselectivities were less affected. The effect of the toluene on the membrane was shown to be reversible when the toluene was removed. © 2010 Elsevier B.V.

  16. Cholesterol detection using optical fiber sensor based on intensity modulation

    Science.gov (United States)

    Budiyanto, Moh; Suhariningsih; Yasin, Moh

    2017-05-01

    The aim of the research is to detect the concentration of cholesterol by using the principle that a laser beam propagation is guided by optical fiber bundle in term of intensity profile through solution with vary concentrations of cholesterol from 0 to 300 ppm. The mechanism of cholesterol concentration detection is the propagation of He-Ne laser beam with wavelength of 632.5 nm through a fiber optic bundle and a solution of cholesterol, then is reflected by a flat mirror and enters receiving fiber. This signal is captured by a silicon detector (SL-818, Newport) in the form of output voltage. The result showed that the output voltage decrease linearly with the increase of concentration of cholesterol with a sensitivity of 0.0004 mV/ppm and the linearity more than 97%.

  17. Linearized Optically Phase-Modulated Fiber Optic Links for Microwave Signal Transport

    Science.gov (United States)

    2009-03-03

    a number of external modulation techniques. For particularly long links, a single or small number of Erbium-Doped Fiber Amplifiers ( EDFA ) could...amplifier (Erbium-Doped Fiber Amplifier, or EDFA ) is present, its noise contribution is caused by beating between the signal and the...the absence of an EDFA , received optical powers that generate photocurrents below approximately 1 mA cause the system noise to be dominated by the

  18. Optical phase modulator utilizing a transparent piezofilm for use with the extrinsic fiber interferometer

    Science.gov (United States)

    Sudarshanam, V. S.; Claus, Richard O.

    1993-03-01

    A piezoelectnc polyvinylidene flouride (PVF2) film with transparent indium tin oxide electrode metallization is placed directly in the path of a single mode fiber output, to form an extrinsic optical interferometer. This device can be used concurrently with another extrinsic inteferometer on a fiber directional coupler to generate a carrier phase modulation on which the signal phase shift is superimposed. Experimental results of the induced phase shifting coefficient are presented for two arrangements of the piezofilm differing in their boundary clamping conditions.

  19. Photonic downconversion for coherent phase-modulated radio-over-fiber links using free-running local oscillator

    DEFF Research Database (Denmark)

    Caballero Jambrina, Antonio; Zibar, Darko; Schäffer, Christian G.

    2011-01-01

    A digital coherent receiver employing photonic downconversion is presented and experimentally demonstrated for phase-modulated radio-over-fiber optical links. Photonic downconversion adds additional advantages to optical phase modulated links by allowing demodulation of signals with RF carrier...

  20. Membrane module and process development for monopolar and bipolar membrane electrodialysis

    OpenAIRE

    Balster, Jörg Henning

    2006-01-01

    This thesis aims to develop more efficient monopolar and bipolar membrane electrodialysis processes. Three main topics have been investigated: 1. Membrane selectivity 2. Concentration polarisation 3. Membrane scaling and fouling

  1. Triple-bore hollow fiber membrane contactor for liquid desiccant based air dehumidification

    KAUST Repository

    Bettahalli, N.M. Srivatsa

    2016-04-26

    Dehumidification is responsible for a large part of the energy consumption in cooling systems in high humidity environments worldwide. Improving efficiency is therefore essential. Liquid desiccants offer a promising solution for dehumidification, as desired levels of humidity removal could be easily regulated. The use of membrane contactors in combination with liquid desiccant is attractive for dehumidification because they prevent direct contact between the humid air and the desiccant, removing both the potential for desiccant carryover to the air and the potential for contamination of the liquid desiccant by dust and other airborne materials, as well as minimizing corrosion. However, the expected additional mass transport barrier of the membrane surface can lower the expected desiccation rate per unit of desiccant surface area. In this context, hollow fiber membranes present an attractive option for membrane liquid desiccant contactors because of their high surface area per unit volume. We demonstrate in this work the performance of polyvinylidene fluoride (PVDF) based triple-bore hollow fiber membranes as liquid desiccant contactors, which are permeable to water vapor but impermeable to liquid water, for dehumidification of hot and humid air.

  2. Analysis of ammonia separation from purge gases in microporous hollow fiber membrane contactors.

    Science.gov (United States)

    Karami, M R; Keshavarz, P; Khorram, M; Mehdipour, M

    2013-09-15

    In this study, a mathematical model was developed to analyze the separation of ammonia from the purge gas of ammonia plants using microporous hollow fiber membrane contactors. A numerical procedure was proposed to solve the simultaneous linear and non linear partial differential equations in the liquid, membrane and gas phases for non-wetted or partially wetted conditions. An equation of state was applied in the model instead of Henry's law because of high solubility of ammonia in water. The experimental data of CO₂-water system in the literature was used to validate the model due to the lack of data for ammonia-water system. The model showed that the membrane contactor can separate ammonia very effectively and with recoveries higher than 99%. SEM images demonstrated that ammonia caused some micro-cracks on the surfaces of polypropylene fibers, which could be an indication of partial wetting of membrane in long term applications. However, the model results revealed that the membrane wetting did not have significant effect on the absorption of ammonia because of very high solubility of ammonia in water. It was also found that the effect of gas velocity on the absorption flux was much more than the effect of liquid velocity.

  3. Investigation of all-optical regeneration based on self-phase modulation in microstructured fibers

    Institute of Scientific and Technical Information of China (English)

    WEI Yan-fen; XU Yong-zhao; Zhang Xia; HUANG Yong-qing; REN Xiao-min

    2007-01-01

    All-optical regeneration based on self-phase modulation in microstructured fibers is studied. The effects of pulse peak power into the fiber,pulse width and filter parameters on the performance of the regenerator are investigated. The effects of normal dispersion and anomalous dispersion of the microstructured fiber on optical regeneration are compared. The numerical results show that optical regeneration can be achieved by using microstructured fibers with normal dispersion or anomalous dispersion,but the normal dispersion decreases the oscillatory structure in the broadened spectra and obtain a better regenerator transfer function. In order to achieve optical regeneration,the input peak power into the microstructured fiber and the filter parameters need to meet certain requirements. By optimizing those parameters,a better regeneration result can be obtained.

  4. Average modulation transfer function of line-array fiber-optic image bundles

    Institute of Scientific and Technical Information of China (English)

    Hui Wang(王慧); Yang Xiang(向阳); Bingxi Yu(禹秉熙)

    2004-01-01

    The image quality evaluation in fiber-optic image bundles was addressed by the modulation transfer function(MTF).With the definition of the contrast transfer function(CTF),the MTF model of line-array fiber-optic image bundles was established and analyzed numerically.The average MTF was carefully evaluated by considering the influence of phase match on the MTF between input pattern and fiber-optic image bundles.In this paper,the average MTF is mean arithmetical value on the MTFs of eight different phases.The results show that,for certain fiber diameter and spatial frequency,the relationship between the core diameter and the average MTF is inverse proportion; for certain fiber cladding thickness,the relationship between the core diameter and the average MTF is also inverse proportion.And at Nyquist frequency,the MTF value is near 0.5.

  5. Effect of Polyvinylidene Fluoride Hollow Fiber Membranes on Mass Transfer of Samarium

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    The influence of swelling and stripping acidity on the mass transfer coefficient based on water phase and the inner diameters of membranes were studied with P507-HCl-Sm as working system in the two different kinds of hollow fiber membranes. Effects of extractant concentration, H+ concentration in aqueous phase and Sm3+ concentration on extraction rate were discussed and the corresponding reaction series were obtained. According to the investigations on the interfacial kinetics, the reaction kinetics equation and reaction rate constant were obtained.

  6. Fiber Ring Laser In-cavity Phase Modulation

    Institute of Scientific and Technical Information of China (English)

    YU Benli; QIAN Jingren; LUO Jiatong; YANG Yinghai

    2001-01-01

    In this paper, experimental results of the in-cavity phase modulation induced by dithering PZT is reported. The dithering PZT can produce strong phase modulation, reshaping the laser output spectrum, but does not affect the laser linewidth, which is measured by homodyne method.

  7. Mathematical modeling of liquid/liquid hollow fiber membrane contactor accounting for interfacial transport phenomena: Extraction of lanthanides as a surrogate for actinides

    Energy Technology Data Exchange (ETDEWEB)

    Rogers, J.D.

    1994-08-04

    This report is divided into two parts. The second part is divided into the following sections: experimental protocol; modeling the hollow fiber extractor using film theory; Graetz model of the hollow fiber membrane process; fundamental diffusive-kinetic model; and diffusive liquid membrane device-a rigorous model. The first part is divided into: membrane and membrane process-a concept; metal extraction; kinetics of metal extraction; modeling the membrane contactor; and interfacial phenomenon-boundary conditions-applied to membrane transport.

  8. Integrated hollow fiber membranes for gas delivery into optical waveguide based photobioreactors.

    Science.gov (United States)

    Ahsan, Syed Saad; Gumus, Abdurrahman; Jain, Aadhar; Angenent, Largus T; Erickson, David

    2015-09-01

    Compact algal reactors are presented with: (1) closely stacked layers of waveguides to decrease light-path to enable larger optimal light-zones; (2) waveguides containing scatterers to uniformly distribute light; and (3) hollow fiber membranes to reduce energy required for gas transfer. The reactors are optimized by characterizing the aeration of different gases through hollow fiber membranes and characterizing light intensities at different culture densities. Close to 65% improvement in plateau peak productivities was achieved under low light-intensity growth experiments while maintaining 90% average/peak productivity output during 7-h light cycles. With associated mixing costs of ∼ 1 mW/L, several magnitudes smaller than closed photobioreactors, a twofold increase is realized in growth ramp rates with carbonated gas streams under high light intensities, and close to 20% output improvement across light intensities in reactors loaded with high density cultures.

  9. Development of Membrane-Based Desiccant Fiber for Vacuum Desiccant Cooling.

    Science.gov (United States)

    Yang, Yifan; Rana, Dipak; Lan, Christopher Q; Matsuura, Takeshi

    2016-06-22

    A novel hydrophobic membrane-based desiccant fiber (MDF) was developed by loading lithium chloride into hydrophobic hollow fiber membranes. The MDF thus made was then tested for vapor absorption under controlled conditions. Furthermore, an MDF pad, which was made by weaving MDF into a piece of garment, was built into a laboratory vacuum desiccant cooling (VDC) setup, which included the MDF pad as the desiccant layer and a cooling towel saturated with water as the water reservoir, to test the cooling effects at atmospheric pressure and vacuum of 25 in. of Hg. Results indicate that MDF is suitable for applications such as in VDC. Mass and heat transfer of vapor absorption by MDF were also analyzed.

  10. Multilayered semiconductor membranes for nanopore ionic conductance modulation.

    Science.gov (United States)

    Gracheva, Maria E; Melnikov, Dmitriy V; Leburton, Jean-Pierre

    2008-11-25

    We explore the possibility of using thin layered semiconductor membranes for electrical control of the ion current flow through a nanopore, thereby operating like tunable ionic transistors. While single layer semiconductor membranes can be voltage tuned to operate as ionic filters or "switches", double layered membranes can rectify the ion current flowing through the nanopore in addition to ion filtering. Triple layer membranes exhibit enhanced functionality with characteristics similar to those of the single and double layer membranes in addition to bidirectional current blocking and switching, thereby operating similar to tunable ionic transistors.

  11. Presynaptic Modulation of the Hippocampal Mossy Fiber Synapse.

    Science.gov (United States)

    1992-09-14

    L., and Ramirez , of Lowry et al. which is more generally applicable. Anal. Biochem. L. 1989. Mossy fiber synaptic reorganization in the epileptic hu...changes in the vesicular pool of I Arias. C.. Montiel, T. and Tapia . R.. Transmitter release in hippo- Glu or in the amount of Glu released in response to

  12. Performance Evaluation of Digital Coherent Receivers for Phase-Modulated Radio-Over-Fiber Links

    DEFF Research Database (Denmark)

    Caballero Jambrina, Antonio; Zibar, Darko; Tafur Monroy, Idelfonso

    2011-01-01

    The performance of optical phase-modulated (PM) radio-over-fiber (RoF) links assisted with coherent detection and digital signal processing (PM-Coh) is analyzed and experimentally demonstrated for next-generation wireless-over-fiber systems. PM-Coh offers high linearity for transparent transport......-bandwidth electronics. Analytical assessment and simulations are used to determine the ultimate performance with respect to laser linewidth, modulation index, and receiver sensitivity. Then, two different scenarios are studied and experimentally demonstrated as an application of PM-Coh links: a high...

  13. Sub-cycle QAM modulation for VCSEL-based optical fiber links

    DEFF Research Database (Denmark)

    Pham, Tien-Thang; Rodes Lopez, Roberto; Jensen, Jesper Bevensee;

    2013-01-01

    QAM modulation utilizing subcarrier frequency lower than the symbol rate is both theoretically and experimentally investigated. High spectral efficiency and concentration of power in low frequencies make sub-cycle QAM signals attractive for optical fiber links with direct modulated light sources....... Real-time generated 10-Gbps 4-level QAM signal in a 7.5-GHz bandwidth utilizing subcarrier frequency at a half symbol rate was successfully transmitted over 20-km SMF using an un-cooled 1.5-μm VCSEL. Only 2.5-dB fiber transmission power penalty was observed with no equalization applied....

  14. Partitioning behavior of aromatic components in jet fuel into diverse membrane-coated fibers.

    Science.gov (United States)

    Baynes, Ronald E; Xia, Xin-Rui; Barlow, Beth M; Riviere, Jim E

    2007-11-01

    Jet fuel components are known to partition into skin and produce occupational irritant contact dermatitis (OICD) and potentially adverse systemic effects. The purpose of this study was to determine how jet fuel components partition (1) from solvent mixtures into diverse membrane-coated fibers (MCFs) and (2) from biological media into MCFs to predict tissue distribution. Three diverse MCFs, polydimethylsiloxane (PDMS, lipophilic), polyacrylate (PA, polarizable), and carbowax (CAR, polar), were selected to simulate the physicochemical properties of skin in vivo. Following an appropriate equilibrium time between the MCF and dosing solutions, the MCF was injected directly into a gas chromatograph/mass spectrometer (GC-MS) to quantify the amount that partitioned into the membrane. Three vehicles (water, 50% ethanol-water, and albumin-containing media solution) were studied for selected jet fuel components. The more hydrophobic the component, the greater was the partitioning into the membranes across all MCF types, especially from water. The presence of ethanol as a surrogate solvent resulted in significantly reduced partitioning into the MCFs with discernible differences across the three fibers based on their chemistries. The presence of a plasma substitute (media) also reduced partitioning into the MCF, with the CAR MCF system being better correlated to the predicted partitioning of aromatic components into skin. This study demonstrated that a single or multiple set of MCF fibers may be used as a surrogate for octanol/water systems and skin to assess partitioning behavior of nine aromatic components frequently formulated with jet fuels. These diverse inert fibers were able to assess solute partitioning from a blood substitute such as media into a membrane possessing physicochemical properties similar to human skin. This information may be incorporated into physiologically based pharmacokinetic (PBPK) models to provide a more accurate assessment of tissue dosimetry of

  15. Characterization of polyethersulfone-polyimide hollow fiber membranes by atomic force microscopy and contact angle goniometery

    OpenAIRE

    Khulbe, K.C.; Feng, C.; Matsuura, T.; Kapantaidakis, G.; Wessling, Matthias; Koops, G.H.

    2003-01-01

    Asymmetric blend polyethersulfone-polyimide (PES-PI) hollow fiber membranes prepared at different air gap and used for gas separation are characterized by atomic force microscopy (inside and out side surfaces) and by measuring the contact angle of out side surface. The outer surface was entirely different than the inner surface, as expected. On the inner surface nodule aggregates were aligned in rows, may be towards the direction of the bore fluid flow. On the outer surface, alignment of nodu...

  16. A high-flux polyimide hollow fiber membrane to minimize footprint and energy penalty for CO2 recovery from flue gas

    KAUST Repository

    Lively, Ryan P.

    2012-12-01

    Using a process-guided approach, a new 6FDA-based polyimide - 6FDA-DAM:DABA(4:1) - has been developed in the form of hollow fiber membranes for CO 2 recovery from post-combustion flue gas streams. Dense film studies on this polymer reveal a CO 2 permeability of 224 Barrers at 40°C at a CO 2 feed pressure of 10psia. The dense films exhibit an ideal CO 2/N 2 permselectivity of 20 at 40°C, which permits their use in a two-step counter-flow/sweep membrane process. Dry-jet, wet-quench, non-solvent-induced phase inversion spinning was used to create defect-free hollow fibers from 6FDA-DAM:DABA(4:1). Membranes with defect-free skin layers, approximately 415nm thick, were obtained with a pure CO 2 permeance of 520GPU at 30°C and an ideal CO 2/N 2 permselectivity of 24. Mixed gas permeation and wet gas permeation are presented for the fibers. The CO 2 permeance in the fibers was reduced by approximately a factor of 2 in feeds with 80% humidity. As a proof-of-concept path forward to increase CO 2 flux, we incorporated microporous ZIF-8 fillers into 6FDA-DAM:DABA(4:1) dense films. Our 6FDA-DAM:DABA(4:1)/ZIF-8 dense film composites (20wt% ZIF-8) had a CO 2 permeability of 550 Barrers and a CO 2/N 2 selectivity of 19 at 35°C. Good adhesion between the ZIF and the 6FDA-DAM:DABA(4:1) matrix was observed. CO 2 capture costs of $27/ton of CO 2 using the current, "non-optimized" membrane are estimated using a custom counterflow membrane model. Hollow fiber membrane modules were estimated to have order-of-magnitude reductions in system footprint relative to spiral-wound modules, thereby making them attractive in current space-constrained coal-fired power stations. © 2012 Elsevier B.V.

  17. Design of robust hollow fiber membranes with high power density for osmotic energy production

    KAUST Repository

    Zhang, Sui

    2014-04-01

    This study highlights the design strategy of highly asymmetric hollow fiber membranes that possess both characteristics of high flux and high mechanical strength to effectively reap the osmotic energy from seawater brine with an ultrahigh power density. An advanced co-extrusion technology was employed to fabricate the polyethersulfone (PES) hollow fiber supports with diversified structures from macrovoid to sponge-like. The microstructure of the supports is found critical for the stability and water permeability of the thin film composite (TFC) membranes. A high porosity in the porous layer is needed to reduce internal concentration polarization, while a thick and relatively dense skin layer underneath the TFC layer is required to maintain good mechanical stability and stress dissipation. The pore size of the supporting layer underneath the TFC layer must be small with a narrow pore size distribution to ensure the formation of a less-defective, highly permeable and mechanically stable TFC layer. The newly developed hollow fiber comprising high asymmetry, high porosity, and a thick skin layer with a small and narrow pore size distribution underneath the TFC layer produces a maximum power density of 24.3W/m2 at 20.0bar by using 1M NaCl as the concentrated brine and deionized (DI) water as the feed. The proposed design strategy for ultrahigh power density membranes clearly advances the osmotic energy production close to commercialization with a quite cost-effective and practicable approach. © 2013 Elsevier B.V.

  18. Thermally moderated hollow fiber sorbent modules in rapidly cycled pressure swing adsorption mode for hydrogen purification

    KAUST Repository

    Lively, Ryan P.

    2012-10-01

    We describe thermally moderated multi-layered pseudo-monolithic hollow fiber sorbents entities, which can be packed into compact modules to provide small-footprint, efficient H2 purification/CO2 removal systems for use in on-site steam methane reformer product gas separations. Dual-layer hollow fibers are created via dry-jet, wet-quench spinning with an inner "active" core of cellulose acetate (porous binder) and zeolite NaY (69 wt% zeolite NaY) and an external sheath layer of pure cellulose acetate. The co-spun sheath layer reduces the surface porosity of the fiber and was used as a smooth coating surface for a poly(vinyl-alcohol) post-treatment, which reduced the gas permeance through the fiber sorbent by at least 7 orders of magnitude, essentially creating an impermeable sheath layer. The interstitial volume between the individual fibers was filled with a thermally-moderating paraffin wax. CO2 breakthrough experiments on the hollow fiber sorbent modules with and without paraffin wax revealed that the "passively" cooled paraffin wax module had 12.5% longer breakthrough times than the "non-isothermal" module. The latent heat of fusion/melting of the wax offsets the released latent heat of sorption/desorption of the zeolites. One-hundred rapidly cycled pressure swing adsorption cycles were performed on the "passively" cooled hollow fiber sorbents using 25 vol% CO2/75 vol% He (H2 surrogate) at 60 °C and 113 psia, resulting in a product purity of 99.2% and a product recovery of 88.1% thus achieving process conditions and product quality comparable to conventional pellet processes. Isothermal and non-isothermal dynamic modeling of the hollow fiber sorbent module and a traditional packed bed using gPROMS® indicated that the fiber sorbents have sharper fronts (232% sharper) and longer adsorbate breakthrough times (66% longer), further confirming the applicability of the new fiber sorbent approach for H2 purification. © 2012, Hydrogen Energy Publications, LLC

  19. Polarization-maintaining higher-order mode fiber module with anomalous dispersion at 1 μm

    DEFF Research Database (Denmark)

    Larsen, Stine Højer Møller; Pedersen, Martin Erland Vestergaard; Grüner-Nielsen, L.

    2012-01-01

    This Letter demonstrates a polarization-maintaining higher-order mode fiber module that has anomalous dispersion at 1 μm. The group velocity dispersion of the module is measured, showing a split of the two polarization axes. The excellent polarization-maintaining properties of the relevant fiber...... modes for the higher-order mode fiber are likewise demonstrated employing a new simple method for the measurement of the beat length of higher-order modes at a single wavelength. The higher-order fiber module is intended for group velocity dispersion compensation....

  20. Polarization-maintaining higher-order mode fiber module with anomalous dispersion at 1 μm.

    Science.gov (United States)

    Larsen, S H M; Pedersen, M E V; Grüner-Nielsen, L; Yan, M F; Monberg, E M; Wisk, P W; Rottwitt, K

    2012-10-15

    This Letter demonstrates a polarization-maintaining higher-order mode fiber module that has anomalous dispersion at 1 μm. The group velocity dispersion of the module is measured, showing a split of the two polarization axes. The excellent polarization-maintaining properties of the relevant fiber modes for the higher-order mode fiber are likewise demonstrated employing a new simple method for the measurement of the beat length of higher-order modes at a single wavelength. The higher-order fiber module is intended for group velocity dispersion compensation.

  1. Cylindrical PVF2 film based fiber optic phase modulator - Phase shift nonlinearity and frequency response

    Science.gov (United States)

    Sudarshanam, V. S.; Claus, Richard O.

    1993-03-01

    A new cylindrical coil configuration for polyvinylidene flouride (PVF2) film based fiber optic phase modulator is studied for the frequency response and nonlinearity of phase shift at the resonance frequency. This configuration, hitherto unapproached for PVF2 film modulators, offers resonance at well defined, controllable and higher frequencies than possible for the flat-strip configuration. Two versions of this configuration are presented that differ strongly in both the resonance frequency and the phase shift nonlinearity coefficient.

  2. Focus control system for stretched-membrane mirror module

    Science.gov (United States)

    Butler, Barry L.; Beninga, Kelly J.

    1991-01-01

    A focus control system dynamically sets and controls the focal length of a reflective membrane supported between a perimeter frame. A rear membrane is also supported between the perimeter frame rearward and spaced apart from a back side of the reflective membrane. The space between the membranes defines a plenum space into which a mass of gas at a first pressure is inserted. The pressure differential between the first pressure and an external pressure, such as the atmospheric pressure, causes the reflective membrane to assume a first curvature relative to a reference plane associated with the perimeter frame. This curvature defines the focal length of the reflective membrane. The focal length is dynamically controlled by changing the volume of the plenum space, thereby changing the first pressure. The system can be used to change or maintain the pressure differential and hence the front membrane curvature. The plenum volume is changed by pushing or pulling on a central section of the rear membrane using a suitable actuator. Sensing means continuously sense the location of the reflective membrane relative to the reference plane. This sensed position is compared to a reference position, and a resulting error signal, comprising the difference between the sensed position and reference position, drives the actuator in a direction to minimize the difference. A vent value compensates for temperature changes or leaks in the closed volume by allowing the pressure differential to be adjusted as required to center the working range of the actuator about the desired focal length.

  3. Hollow Fiber Spacesuit Water Membrane Evaporator Development and Testing for Advanced Spacesuits

    Science.gov (United States)

    Bue, Grant C.; Trevino, Luis A.; Tsioulos, Gus; Settles, Joseph; Colunga, Aaron; Vogel, Matthew; Vonau, Walt

    2010-01-01

    The spacesuit water membrane evaporator (SWME) is being developed to perform the thermal control function for advanced spacesuits to take advantage of recent advances in micropore membrane technology in providing a robust heat-rejection device that is potentially less sensitive to contamination than is the sublimator. Principles of a sheet membrane SWME design were demonstrated using a prototypic test article that was tested in a vacuum chamber at JSC in July 1999. The Membrana Celgard X50-215 microporous hollow fiber (HoFi) membrane was selected after recent contamination tests as the most suitable candidate among commercial alternatives for HoFi SWME prototype development. A design that grouped the fiber layers into stacks, which were separated by small spaces and packaged into a cylindrical shape, was developed into a full-scale prototype consisting 14,300 tube bundled into 30 stacks, each of which are formed into a chevron shape and separated by spacers and organized into three sectors of ten nested stacks. Vacuum chamber testing has been performed characterize heat rejection as a function of inlet water temperature and water vapor backpressure and to show contamination resistance to the constituents expected to be found in potable water produced by the distillation processes. Other tests showed the tolerance to freezing and suitability to reject heat in a Mars pressure environment.

  4. EVALUATION METHOD FOR PARASITIC EFFECTS OF THE ELECTRO-OPTICAL MODULATOR IN A FIBER OPTIC GYROSCOPE

    Directory of Open Access Journals (Sweden)

    S. A. Volkovskiy

    2016-09-01

    Full Text Available Subject of Research.The paper proposes an original method for studying the parasitic effects in the electro-optic modulator of the fiber optic gyroscope. Proposed method is based on the usage of a special waveform phase modulation signal. Method. The essence of the proposed method lies in modification of serrodyne modulation signal, thereby providing a periodic displacement of the phase difference signal to the maximum of the interference curve. In this case, the intensity level reflects the influence of parasitic effects with the degree of manifestation being determined by the sequence of voltage control signals applied to the modulator. Enumeration of combinations of control signals and the corresponding intensity levels gives the possibility to observe an empirical dependence of the parasitic effects and use it later for compensation. Main Results. The efficiency of the proposed method is demonstrated by the program model of the fiber optic gyroscope. The results of the method application on a production sample of the device were obtained. Comparison with the results of direct estimate of the parasitic intensity modulation effect testifies to the effectiveness of the proposed method. Practical Relevance. The method can be used as a diagnostic tool to quantify the influence of parasitic effects in the electro-optic modulator of the fiber optic gyroscope as well as for their subsequent compensation.

  5. Olefins-selective asymmetric carbon molecular sieve hollow fiber membranes for hybrid membrane-distillation processes for olefin/paraffin separations

    KAUST Repository

    Xu, Liren

    2012-12-01

    In this paper, the development of asymmetric carbon molecular sieve (CMS) hollow fiber membranes and advanced processes for olefin/paraffin separations based on the CMS membranes are reported. Membrane-based olefin/paraffin separations have been pursued extensively over the past decades. CMS membranes are promising to exceed the performance upper bound of polymer materials and have demonstrated excellent stability for gas separations. Previously, a substructure collapse phenomenon was found in Matrimid ® precursor derived CMS fiber. To overcome the permeance loss due to the increased separation layer thickness, 6FDA-DAM and 6FDA/BPDA-DAM precursors were selected as potential new precursors for carbon membrane formation. Defect-free asymmetric 6FDA-DAM and 6FDA/BPDA-DAM hollow fibers were successfully fabricated from a dry-jet/wet-quench spinning process. Polymer rigidity, glass-rubber transition and asymmetric morphology were correlated. CMS hollow fiber membranes produced from 6FDA-polymer precursors showed significant improvement in permeance for ethylene/ethane and propylene/propane separations. Further studies revealed that the CMS membranes are olefins-selective, which means the membranes are able to effectively separate olefins (ethylene and propylene) from paraffins (ethane and propane). This unique feature of CMS materials enables advanced hybrid membrane-distillation process designs. By using the olefins-selective membranes, these new processes may provide advantages over previously proposed retrofitting concepts. Further applications of the membranes are explored for hydrocarbons processes. Significant energy savings and even reduced footprint may be achieved in olefins production units. © 2012 Elsevier B.V.

  6. Complex collagen fiber and membrane morphologies of the whole porcine aortic valve.

    Directory of Open Access Journals (Sweden)

    Christopher A Rock

    Full Text Available OBJECTIVES: Replacement aortic valves endeavor to mimic native valve function at the organ, tissue, and in the case of bioprosthetic valves, the cellular levels. There is a wealth of information about valve macro and micro structure; however, there presently is limited information on the morphology of the whole valve fiber architecture. The objective of this study was to provide qualitative and quantitative analyses of whole valve and leaflet fiber bundle branching patterns using a novel imaging system. METHODS: We developed a custom automated microscope system with motor and imaging control. Whole leaflets (n = 25 were imaged at high resolution (e.g., 30,000×20,000 pixels using elliptically polarized light to enhance contrast between structures without the need for staining or other methods. Key morphologies such as fiber bundle size and branching were measured for analyses. RESULTS: The left coronary leaflet displayed large asymmetry in fiber bundle organization relative to the right coronary and non-coronary leaflets. We observed and analyzed three main patterns of fiber branching; tree-like, fan-like, and pinnate structures. High resolution images and quantitative metrics are presented such as fiber bundle sizes, positions, and branching morphological parameters. SIGNIFICANCE: To our knowledge there are currently no high resolution images of whole fresh leaflets available in the literature. The images of fiber/membrane structures and analyses presented here could be highly valuable for improving the design and development of more advanced bioprosthetic and/or bio-mimetic synthetic valve replacements.

  7. Preparation and characterization of PVDF-glass fiber composite membrane reinforced by interfacial UV-grafting copolymerization.

    Science.gov (United States)

    Luo, Nan; Xu, Rongle; Yang, Min; Yuan, Xing; Zhong, Hui; Fan, Yaobo

    2015-12-01

    A novel inorganic-organic composite membrane, namely poly(vinylidene fluoride) PVDF-glass fiber (PGF) composite membrane, was prepared and reinforced by interfacial ultraviolet (UV)-grafting copolymerization to improve the interfacial bonding strength between the membrane layer and the glass fiber. The interfacial polymerization between inorganic-organic interfaces is a chemical cross-linking reaction that depends on the functionalized glass fiber with silane coupling (KH570) as the initiator and the polymer solution with acrylamide monomer (AM) as the grafting block. The Fourier transform infrared spectrometer-attenuated total reflectance (FTIR-ATR) spectra and the energy dispersive X-ray (EDX) pictures of the interface between the glass fiber and polymer matrix confirmed that the AM was grafted to the surface of the glass fiber fabric and that the grafting polymer was successfully embedded in the membrane matrix. The formation mechanisms, permeation, and anti-fouling performance of the PGF composite membrane were measured with different amounts of AM in the doping solutions. The results showed that the grafting composite membrane improved the interfacial bonding strength and permeability, and the peeling strength was improved by 32.6% for PGF composite membranes with an AM concentration at 2wt.%.

  8. Air gap membrane distillation. 2. Model validation and hollow fibre module performance analysis

    NARCIS (Netherlands)

    Guijt, C.M.; Meindersma, G.W.; Reith, T.; de Haan, A.B.

    2005-01-01

    In this paper the experimental results of counter current flow air gap membrane distillation experiments are presented and compared with predictive model calculations. Measurements were carried out with a cylindrical test module containing a single hollow fibre membrane in the centre and a

  9. Enhanced forward osmosis from chemically modified polybenzimidazole (PBI) nanofiltration hollow fiber membranes with a thin wall

    KAUST Repository

    Wang, Kai Yu

    2009-04-01

    To develop high-flux and high-rejection forward osmosis (FO) membranes for water reuses and seawater desalination, we have fabricated polybenzimidazole (PBI) nanofiltration (NF) hollow fiber membranes with a thin wall and a desired pore size via non-solvent induced phase inversion and chemically cross-linking modification. The cross-linking by p-xylylene dichloride can finely tune the mean pore size and enhance the salt selectivity. High water permeation flux and improved salt selectivity for water reuses were achieved by using the 2-h modified PBI NF membrane which has a narrow pore size distribution. Cross-linking at a longer time produces even a lower salt permeation flux potentially suitable for desalination but at the expense of permeation flux due to tightened pore sizes. It is found that draw solution concentration and membrane orientations are main factors determining the water permeation flux. In addition, effects of membrane morphology and operation conditions on water and salt transport through membrane have been investigated. © 2008 Elsevier Ltd. All rights reserved.

  10. Recovery Properties of Polysulfone Hollow Fiber Chelating Membrane Modified with Thiourea for Mercury ( Ⅱ )

    Institute of Scientific and Technical Information of China (English)

    WANG Bing; XIAO Feng; HUANG Lei

    2007-01-01

    The adsorption isotherms of the polysulfone hollow fiber chelating membrane modified with thiourea as chelating groups for Hg2+ were determined. The effects of mobile phase conditions and the operating parameters on removal performance of the chelating membrane for Hg2+ were also investigated. The recovery of Hg2+ decreased at low pH and the optimum range of pH was from 6 to 7. The feed concentration effected on recovery of Hg2+ at the specified loading amount of Hg2+. The Hg2+ could be removed from different concentration feed solution by chelating membrane. The increase of feed flow rate led to slight decrease of recovery of Hg2+ at the specified loading amount of Hg2+. The chelating membrane could be operated at height feed flow rate and a large-scale removal of Hg2+ could be realized. With the increase of load amount, Hg2+ recovery decreased, but the saturation degree of chelating membrane increased. According to required recovery of Hg2+ and the saturation degree of chelating membrane, the optimum loading amount of Hg2+ should be selected in the actual removal of Hg2+.

  11. Cost-effective bidirectional digitized radio-over-fiber systems employing sigma delta modulation

    Science.gov (United States)

    Lee, Kyung Woon; Jung, HyunDo; Park, Jung Ho

    2016-11-01

    We propose a cost effective digitized radio-over-fiber (D-RoF) system employing a sigma delta modulation (SDM) and a bidirectional transmission technique using phase modulated downlink and intensity modulated uplink. SDM is transparent to different radio access technologies and modulation formats, and more suitable for a downlink of wireless system because a digital to analog converter (DAC) can be avoided at the base station (BS). Also, Central station and BS share the same light source by using a phase modulation for the downlink and an intensity modulation for the uplink transmission. Avoiding DACs and light sources have advantages in terms of cost reduction, power consumption, and compatibility with conventional wireless network structure. We have designed a cost effective bidirectional D-RoF system using a low pass SDM and measured the downlink and uplink transmission performance in terms of error vector magnitude, signal spectra, and constellations, which are based on the 10MHz LTE 64-QAM standard.

  12. Freestanding manganese dioxide nanosheet network grown on nickel/polyvinylidene fluoride coaxial fiber membrane as anode materials for high performance lithium ion batteries

    Science.gov (United States)

    Zhang, Yan; Luo, Zhongping; Xiao, Qizhen; Sun, Tianlei; Lei, Gangtie; Li, Zhaohui; Li, Xiaojing

    2015-11-01

    A novel manganese dioxide (MnO2) nanosheet network grown on nickel/polyvinylidene fluoride (Ni/PVDF) coaxial fiber membrane is successfully fabricated by a three-step route: the polyvinylidene fluoride fiber membrane is prepared by electrospinning method, and then the Ni(shell)/PVDF(core) coaxial fiber membrane with core-shell structure can be obtained by the electroless deposition, and finally the manganese dioxide nanosheet network grown on Ni/PVDF coaxial fiber membrane can be achieved by using a simple hydrothermal treatment. This as-prepared binder-free and flexible composite membrane is directly used as anode for lithium ion batteries. The excellent electrochemical performance of the composite membrane can be attributed to the unique combinative effects of nanosized MnO2 network and conductive Ni/PVDF fiber matrix as well as the porous structure of composite fiber membrane.

  13. Outer-selective thin film composite (TFC) hollow fiber membranes for osmotic power generation

    KAUST Repository

    Le, Ngoc Lieu

    2016-01-14

    The pressure-retarded osmosis (PRO) process is a green technique for power generation to respond the world\\'s need of energy sustainability. In this study, we have developed the vital component of the process, i.e. membrane, in the configuration of the outer-selective thin-film composite (TFC) hollow fiber, which is more practical than other configurations in the real applications. The support layer morphology and the formation of the selective polyamide layer have been optimized for a good PRO performance. The results show that the bore fluid with higher amount of the solvent N-methyl-2-pyrrolidone leads to full finger-like hollow fibers, which provide higher flux but lower pressure tolerance. The addition of higher amount of diethylene glycol into the dope solution, improves the pore formation and suppresses the macrovoid formation, while properly lowering the take-up speed increases their wall thickness and pressure tolerance. A simple alcohol-pre-wetting approach on the fiber support leads to a smooth and thin polyamide layer, which is favorable for a high water flux and power density. Its efficiency follows this order: n-propanol>ethanol>methanol>water. The n-propanol pre-wetted TFC membrane can tolerate 17 bar with a peak power density of 9.59 W/m2 at room temperature, using 1 M NaCl solution as the draw solution and DI water as feed. This work demonstrates the potential of outer-selective TFC hollow fiber membranes for energy conversion via PRO process, provides useful database to fabricate suitable support morphology and raise a simple technique to practically form a thin and smooth polyamide layer.

  14. Enhancement of the flux for polypropylene hollow fiber membrane in a submerged membrane-bioreactor by surface modification

    Institute of Scientific and Technical Information of China (English)

    YU Hai-yin; LEI Hao; XU Zhi-kang

    2006-01-01

    To improve its limiting flux and antifouling characteristics in a submerged membrane-bioreactor (SMBR) for wastewater treatment, polypropylene hollow fiber microporous membrane (PPHFMM) was surface-modified by the plasma-induced immobilization of poly (N-vinyl-2-pyrrolidone) (PVP) and the plasma treatment with different gases respectively. Attenuated total reflection-Fourier transform infrared spectroscopy (FT-IR/ATR), X-ray photoelectron spectroscopy (XPS) and field emission scanning electron microscope (FE-SEM) were used to characterize the structural and morphological changes on the membrane surface. Water contact angle was measured by the sessile drop method. It was found that the water contact angle was 128.8, 72.3, 62.7, 74.4, 79.1,86.3, and 71.3° for the nascent, PVP-immobilized, air,O2, Ar, CO2 and H2O plasma treated PPHFMM, respectively. The SMBR was operated at fixed transmembrane pressure to determine the limiting flux for the PPHFMM before and after surface modification.Results showed that the limiting flux appeared to be 103, 159, 117, 133, 136, 121 and 152 L/(m2·h) for the nascent, PVP-immobilized,air, O2, Ar, CO2 and H2O plasma treated PPHFMM, respectively. After continuous operation for about 50 h in the SMBR, the antifouling characteristics were improved to some extent.

  15. Optically envelope detected QAM and QPSK RF modulated signals in hybrid wireless-fiber systems

    DEFF Research Database (Denmark)

    Tafur Monroy, Idelfonso; Prince, Kamau; Seoane, Jorge;

    2009-01-01

    from a 1.6 GHz carrier frequency to an IF at 500 MHz, requiring no high frequency local oscillator and mixer at the remote base station. This result proves the feasibility of optical envelope detection for complex modulation formats of RF signals for hybrid wireless-fiber transmission links....

  16. Characterization and Modification of Electrospun Fiber Mats for Use in Composite Proton Exchange Membranes

    Science.gov (United States)

    Mannarino, Matthew Marchand

    . Post-spin thermal annealing was used to modify the fiber morphology, inter-fiber welding, and crystallinity within the fibers. Morphological changes, in-plane tensile response, friction coefficient, and wear rate were characterized as functions of the annealing temperature. The Young's moduli, yield stresses and toughnesses of the PA 6(3)T nonwoven mats improved by two- to ten-fold when annealed slightly above the glass transition temperature, but at the expense of mat porosity. The mechanical and tribological properties of the thermally annealed P A 6,6 fiber mats exhibited significant improvements through the Brill transition temperature, comparable to the improvements observed for amorphous P A 6(3)T electrospun mats annealed near the glass transition temperature. The wear rates for both polymer systems correlate with the yield properties of the mat, in accordance with a modified Ratner-Lancaster model. The variation in mechanical and tribological properties of the mats with increasing annealing temperature is consistent with the formation of fiber-to-fiber junctions and a mechanism of abrasive wear that involves the breakage of these junctions between fibers. A mechanically robust proton exchange membrane with high ionic conductivity and selectivity is an important component in many electrochemical energy devices such as fuel cells, batteries, and photovoltaics. The ability to control and improve independently the mechanical response, ionic conductivity, and selectivity properties of a membrane is highly desirable in the development of next generation electrochemical devices. In this thesis, the use of layer-by-layer (LbL) assembly of polyelectrolytes is used to generate three different polymer film morphologies on highly porous electrospun fiber mats: webbed, conformal coating, and pore-bridging films. Specifically, depending on whether a vacuum is applied to the backside of the mat or not, the spray-LbL assembly either fills the voids of the mat with the proton

  17. Carbon nanotube coated fiber Bragg grating for photomechanical optic modulator.

    Science.gov (United States)

    Shivananju, B N; Suri, Ashish; Asokan, Sundarrajan; Misra, Abha

    2013-09-01

    We have demonstrated novel concept of utilizing the photomechanical actuation in carbon nanotubes (CNTs) to tune and reversibly switch the Bragg wavelength. When fiber Bragg grating coated with CNTs (CNT-FBG) is exposed externally to a wide range of optical wavelengths, e.g., ultraviolet to infrared (0.2-200 μm), a strain is induced in the CNTs which alters the grating pitch and refractive index in the CNT-FBG system resulting in a shift in the Bragg wavelength. This novel approach will find applications in telecommunication, sensors and actuators, and also for real time monitoring of the photomechanical actuation in nanoscale materials.

  18. Membrane potential modulates plasma membrane phospholipid dynamics and K-Ras signaling

    Science.gov (United States)

    Zhou, Yong; Wong, Ching-On; Cho, Kwang-jin; van der Hoeven, Dharini; Liang, Hong; Thakur, Dhananiay P.; Luo, Jialie; Babic, Milos; Zinsmaier, Konrad E.; Zhu, Michael X.; Hu, Hongzhen; Venkatachalam, Kartik; Hancock, John F.

    2015-01-01

    Plasma membrane depolarization can trigger cell proliferation, but how membrane potential influences mitogenic signaling is uncertain. Here, we show that plasma membrane depolarization induces nanoscale reorganization of phosphatidylserine and phosphatidylinositol 4,5-bisphosphate but not other anionic phospholipids. K-Ras, which is targeted to the plasma membrane by electrostatic interactions with phosphatidylserine, in turn undergoes enhanced nanoclustering. Depolarization-induced changes in phosphatidylserine and K-Ras plasma membrane organization occur in fibroblasts, excitable neuroblastoma cells, and Drosophila neurons in vivo and robustly amplify K-Ras–dependent mitogen-activated protein kinase (MAPK) signaling. Conversely, plasma membrane repolarization disrupts K-Ras nanoclustering and inhibits MAPK signaling. By responding to voltage-induced changes in phosphatidylserine spatiotemporal dynamics, K-Ras nanoclusters set up the plasma membrane as a biological field-effect transistor, allowing membrane potential to control the gain in mitogenic signaling circuits. PMID:26293964

  19. Coherent combining of fiber-laser-pumped frequency converters using all fiber electro-optic modulator for active phase control

    Science.gov (United States)

    Bourdon, P.; Durécu, A.; Canat, G.; Le Gouët, J.; Goular, D.; Lombard, L.

    2015-03-01

    Coherent beam combining (CBC) by active phase control could be useful for power scaling fiber-laser-pumped optical frequency converters like OPOs. However, a phase modulator operating at the frequency-converted wavelength is needed, which is non standard component. Fortunately, nonlinear conversion processes rely on a phase-matching condition correlating, not only the wave vectors of the coupled waves, but also their phases. This paper demonstrates that, using this phase correlation for indirect control of the phase, coherent combining of optical frequency converters is feasible using standard all-fibered electro-optic modulators. For the sake of demonstration, this new technique is experimentally applied twice for continuous wave second-harmonic-generator (SHG) combination: i) combining 2 SHG of 1.55-μm erbium-doped fiber amplifiers in PPLN crystals generating 775-nm beams; ii) combining 2 SHG of 1.064-μm ytterbium-doped fiber amplifiers in LBO crystals generating 532-nm beams. Excellent CBC efficiency is achieved on the harmonic waves in both these experiments, with λ/20 and λ/30 residual phase error respectively. In the second experiment, I/Q phase detection is added on fundamental and harmonic waves to measure their phase variations simultaneously. These measurements confirm the theoretical expectations and formulae of correlation between the phases of the fundamental and harmonic waves. Unexpectedly, in both experiments, when harmonic waves are phase-locked, a residual phase difference remains between the fundamen tal waves. Measurements of the spectrum of these residual phase differences locate them above 50 Hz, revealing that they most probably originate in fast-varying optical path differences induced by turbulence and acoustic-waves on the experimental breadboard.

  20. Dynamics of an erbium-doped fiber laser with pump modulation: theory and experiment

    Science.gov (United States)

    Pisarchik, Alexander N.; Kir'yanov, Alexander V.; Barmenkov, Yuri O.; Jaimes-Reátegui, Rider

    2005-10-01

    We study in detail the complex dynamics of an erbium-doped fiber laser that has been subjected to harmonic modulation of a diode pump laser. We introduce a novel laser model that describes perfectly all experimentally observed features. The model is generalized to a nonlinear oscillator. The coexistence of different periodic and chaotic regimes and their relation to subharmonics and higher harmonics of the relaxation oscillation frequency of the laser are demonstrated with codimensional-one and codimensional-two bifurcation diagrams in parameter space of the modulation frequency and amplitude. The phase difference between the laser response and the pump modulation is also investigated.

  1. Supercontinuum Generation Enhanced by Cross-phase Modulation in Dispersion-flattened and Decreasing Fiber

    Institute of Scientific and Technical Information of China (English)

    XU Wen-cheng; XU Yong-zhao; YU Bing-tao; CUI Hu; CHEN Yong-zhu; LIU Song-hao

    2005-01-01

    Supercontinuum spectrum generation in a dispersion-flattened and decreasing fiber with two orthogonally polarized pulses was simulated and calculated. The research results indicated that the supercontinuum spectrum generated by two orthogonally polarized pulses is wider and flatter than that generated by single polarized pulse due to cross-phase modulation. The cross-phase modulation effect can enhance the supercontinuum spectrum generation. When the pump power of the input pulse is lower, the enhancement of supercontinuum spectrum generation by cross-phase modulation effect is more significant.

  2. Ion transport membrane module and vessel system with directed internal gas flow

    Science.gov (United States)

    Holmes, Michael Jerome; Ohrn, Theodore R.; Chen, Christopher Ming-Poh

    2010-02-09

    An ion transport membrane system comprising (a) a pressure vessel having an interior, an inlet adapted to introduce gas into the interior of the vessel, an outlet adapted to withdraw gas from the interior of the vessel, and an axis; (b) a plurality of planar ion transport membrane modules disposed in the interior of the pressure vessel and arranged in series, each membrane module comprising mixed metal oxide ceramic material and having an interior region and an exterior region; and (c) one or more gas flow control partitions disposed in the interior of the pressure vessel and adapted to change a direction of gas flow within the vessel.

  3. [Effect of spectrum distortion on modulation transfer function in imaging fiber-optic spectrometer].

    Science.gov (United States)

    Cheng, Xin; Wang, Jing; Zhang, Bao; Hong, Yong-Feng

    2011-10-01

    Imaging fiber bundles were introduced to dispersion imaging spectrometer and substituted for slit, connecting the telescope and spectrometer to yield the imaging fiber-optic spectrometer. It is a double sampling system, the misalignment between image of optical fiber and detector pixel has arisen because of the spectrum distortion of spectrometer, which affected the second sampling process, and the modulation transfer function (MTF) therefore degraded. Optical transfer function of sampling process was derived from line spread function. The effect of spectrum distortion on system MTF was analyzed, and a model evaluating the MTF of imaging fiber-optic spectrometer was developed. Compared to the computation model of MTF of slit imaging spectrometer, a MTF item of sampling by optical fiber and a MTF item of misalignment arising from spectrum distortion were added in this model. Employing this, the MTF of an airborne imaging fiber-optic spectrometer for visible near infrared band was evaluated. The approach ro deriving and developing the MTF model has a reference signification for the computation of MTF of double sampling system, which can direct the design of imaging fiber-optic spectrometer also.

  4. The aqueous layers within the myelin sheath modulate the membrane properties of simulated hereditary demyelinating neuropathies.

    Science.gov (United States)

    Stephanova, D I; Krustev, S M; Daskalova, M

    2011-03-01

    To expand our studies on the mechanisms underlying the clinical decline of the nerve excitability properties in patients with hereditary demyelinating neuropathies, the contribution of myelin sheath aqueous layers on multiple membrane properties of simulated fiber demyelinations is investigated. Three progressively greater degrees of internodal systematic demyelinations (two mild and one severe termed as ISD1, ISD2 and ISD3, respectively) without/with aqueous layers are simulated using our previous multi-layered model of human motor nerve fiber. The calculated multiple membrane excitability properties are as follows: potentials (intracellular action, electrotonic), strength-duration time constants, rheobasic currents and recovery cycles. They reflect the propagating, accommodative and adaptive processes in the fibers. The results show that all membrane properties, except for the strength-duration time constants and refractoriness, worsen when the myelin lamellae and their corresponding aqueous layers are uniformly reduced along the fiber length. The effect of the aqueous layers is significantly higher on the accommodative and adaptive processes than on the propagating processes in the fibers. Our multi-layered model better approximated some of the functional deficits documented for axons of patients with Charcot-Marie-Tooth disease type 1A. The study provides new and important information on the mechanisms underlying the pathophysiology of hereditary demyelinating neuropathies.

  5. Antiplasticization and plasticization of Matrimid® asymmetric hollow fiber membranes. Part B. Modeling

    KAUST Repository

    Lee, Jong Suk

    2010-03-15

    A previous paper characterized effects of exposure of Matrimid® asymmetric fibers to either toluene or n-heptane or a combination of both contaminants during permeation. In all cases, reductions in the carbon dioxide permeance and the carbon dioxide/methane selectivity were observed for both annealed and non-annealed samples. In this paper, the respective potential impacts of competitive sorption, fiber compaction, and antiplasticization/plasticization on membrane performance during contaminant exposure are quantified and analyzed. The combined impact of competitive sorption and antiplasticization/plasticization are shown to account for the loss in membrane performance observed during exposure to highly sorbing feed stream contaminants. The dual mode transport model for penetrant mixtures was used to explain reduction in CO2 permeance due to competitive sorption effects, while free volume-based modeling explained decrease in CO2 permeance due to antiplasticization. Finally, the impact on CO2 permeance during exposure of the annealed Matrimid® fibers to contaminants is analyzed. The analysis is based on reduction in segmental mobility expected due to reduction of residual unrelaxed volume as compared to unanealed sample. © 2010.

  6. Septins as modulators of endo-lysosomal membrane traffic

    Directory of Open Access Journals (Sweden)

    Kyungyeun Song

    2016-11-01

    Full Text Available Septins constitute a family of GTP-binding proteins, which assemble into non-polar filaments in a nucleotide-dependent manner. These filaments can be recruited to negatively charged membrane surfaces. When associated with membranes septin filaments can act as diffusion barriers, which confine subdomains of distinct biological functions. In addition, they serve scaffolding roles by recruiting cytosolic proteins and other cytoskeletal elements. Septins have been implicated in a large variety of membrane-dependent processes, including cytokinesis, signaling, cell migration, and membrane traffic, and several family members have been implicated in disease. However, surprisingly little is known about the molecular mechanisms underlying their biological functions. This review summarizes evidence in support of regulatory roles of septins during endo-lysosomal sorting, with a particular focus on phosphoinositides, which serve as spatial landmarks guiding septin recruitment to distinct subcellular localizations.

  7. Experimental investigation and modeling of industrial oily wastewater treatment using modified polyethersulfone ultrafiltration hollow fiber membranes

    Energy Technology Data Exchange (ETDEWEB)

    Salahi, Abdolhamid; Mohammadi, Toraj [Iran University of Science and Technology (IUST), Tehran (Iran, Islamic Republic of); Behbahani, Reza Mosayebi [Petroleum University of Technology (PUT), Ahwaz (Iran, Islamic Republic of); Hemmati, Mahmood [Research Institute of Petroleum Industry, Tehran (Iran, Islamic Republic of)

    2015-06-15

    Hollow fiber membranes were prepared from polyethersulfone/additives/NMP and DMSO system via phase inversion induced by precipitation in non-solvent coagulation bath. The interaction effects of polyethylene-glycol (PEG), propionic-acid (PA), Tween-20, PEG molecular weight and polyvinyl-pyrrolidone (PVP) on morphology and performance of synthesized membranes were investigated. Taguchi method (L{sub 16} orthogonal array) was used initially to plan a minimum number of experiments. 32 membranes were synthesized (with two replications) and their permeation flux and TOC rejection properties to oily wastewater treatment were studied. The obtained results indicated that addition of PA to spinning dope decreases flux while it increases TOC rejection of prepared membranes. Also, the result shows that addition of PVP, Tween-20 and PEG content in spinning dope enhances permeation flux while reducing TOC rejection. The obtained results indicated that the synthesized membranes was effective and suitable for treatment of the oily wastewater to achieve up to 92.6, 98.2, and 98.5% removal of TOC, TSS, and OGC, respectively with a flux of 247.19 L/(m{sup 2}h). Moreover, Hermia's models were used for permeation flux decline prediction. Experimental data and models predictions were compared. The results showed that there is reasonable agreement between experimental data and the cake layer model followed by the intermediate blocking model.

  8. Functional Properties of Punica granatum L. Juice Clarified by Hollow Fiber Membranes

    Directory of Open Access Journals (Sweden)

    Francesco Galiano

    2016-07-01

    Full Text Available There is currently much interest in pomegranate juice because of the high content of phenolic compounds. Moreover, the interest in the separation of bioactive compounds from natural sources has remarkably grown. In this work, for the first time, the Punica granatum L. (pomegranate juice—clarified by using polyvinylidene fluoride (PVDF and polysulfone (PSU hollow fiber (HF membranes prepared in the laboratory—was screened for its antioxidant properties by using different in vitro assays, namely 2,2-diphenyl-1-picrylhydrazyl (DPPH, 2,2'-azino-bis-(3-ethylbenzothiazoline-6-sulphonic acid (ABTS, Ferric Reducing Antioxidant Power (FRAP, and β-carotene bleaching tests, and for its potential inhibitory activity of the carbohydrate-hydrolysing enzymes, α-amylase and α-glucosidase. The effects of clarification on quality characteristics of the juice were also investigated in terms of total phenols, flavonoids, anthocyanins, and ascorbic acid. Experimental results indicated that PVDF membranes presented a lower retention towards healthy phytochemicals in comparison to PSU membranes. Accordingly, the juice clarified with PVDF membranes showed the best antioxidant activity. Moreover, the treatment with PVDF membranes produced a clarified juice with 2.9-times fold higher α-amylase inhibitory activity in comparison to PSU (IC50 value of 75.86 vs. 221.31 μg/mL, respectively. The same trend was observed using an α-glucosidase inhibition test. These results highlight the great potential of the clarified juice as a source of functional constituents.

  9. Performance Investigation of O-Ring Vacuum Membrane Distillation Module for Water Desalination

    Directory of Open Access Journals (Sweden)

    Adnan Alhathal Alanezi

    2016-01-01

    Full Text Available A new O-ring flat sheet membrane module design was used to investigate the performance of Vacuum Membrane Distillation (VMD for water desalination using two commercial polytetrafluoroethylene (PTFE and polyvinylidene fluoride (PVDF flat sheet hydrophobic membranes. The design of the membrane module proved its applicability for achieving a high heat transfer coefficient of the order of 103 (W/m2 K and a high Reynolds number (Re. VMD experiments were conducted to measure the heat and mass transfer coefficients within the membrane module. The effects of the process parameters, such as the feed temperature, feed flow rate, vacuum degree, and feed concentration, on the permeate flux have been investigated. The feed temperature, feed flow rate, and vacuum degree play an important role in enhancing the performance of the VMD process; therefore, optimizing all of these parameters is the best way to achieve a high permeate flux. The PTFE membrane showed better performance than the PVDF membrane in VMD desalination. The obtained water flux is relatively high compared to that reported in the literature, reaching 43.8 and 52.6 (kg/m2 h for PVDF and PTFE, respectively. The salt rejection of NaCl was higher than 99% for both membranes.

  10. Fiber faceplate modulation readout in Bi-material micro-cantilever mirror array imaging system

    Science.gov (United States)

    Hui, Mei; Xia, Zhengzheng; Liu, Ming; Dong, Liquan; Liu, Xiaohua; Zhao, Yuejin

    2016-05-01

    Fiber faceplate modulation was applied to read out the precise actuation of silicon-based, surface micro-fabricated cantilever mirrors array in optical imaging system. The faceplate was made by ordered bundles consisting of as many as ten thousands fibers. The transmission loss of an individual fiber in the bundles was 0.35dB/cm and the cross talk between neighboring fibers in the faceplate was about 15%. Micro-cantilever mirrors array (Focal-Plane Array (FPA)) which composed of two-level bi-material pixels, absorb incident infrared flux and result in a temperature increase. The temperature distribution of incident flux transformed to the deformation distribution in FPA which has a very big difference in coefficients of thermal expansion. FPA plays the roles of target sensing and has the characteristics of high detection sensitivity. Instead of general filter such as knife edge or pinhole, fiber faceplate modulate the beam reflected by the units of FPA. An optical readout signal brings a visible spectrum into pattern recognition system, yielding a visible image on monitor. Thermal images at room temperature have been obtained. The proposed method permits optical axis compact and image noise suppression.

  11. Symbiotic hollow fiber membrane photobioreactor for microalgal growth and bacterial wastewater treatment.

    Science.gov (United States)

    Vu, Linh T K; Loh, Kai-Chee

    2016-11-01

    A hollow fiber membrane photobioreactor (HFMP) for microalgal growth and bacterial wastewater treatment was developed. C. vulgaris culture was circulated through one side of the HFMP and P. putida culture was circulated through the other. A symbiotic relationship was demonstrated as reflected by the photo-autotrophic growth of C. vulgaris using CO2 provided by P. putida and biodegradation of 500mg/L glucose by P. putida utilizing photosynthetic O2 produced by C. vulgaris. Performance of the HFMP was significantly enhanced when the microalgal culture was circulated through the lumen side of the HFMP: the average percentage of glucose degraded per 8-h cycle was as high as 98% and microalgal biomass productivity was increased by 69% compared to the reversed orientation. Enhanced glucose biodegradation was achieved in an HFMP packed with more fibers indicating the easy scalability of the HFMP for increased wastewater treatment efficiency.

  12. Pb2+ as modulator of protein-membrane interactions.

    Science.gov (United States)

    Morales, Krystal A; Lasagna, Mauricio; Gribenko, Alexey V; Yoon, Youngdae; Reinhart, Gregory D; Lee, James C; Cho, Wonhwa; Li, Pingwei; Igumenova, Tatyana I

    2011-07-13

    Lead is a potent environmental toxin that mimics the effects of divalent metal ions, such as zinc and calcium, in the context of specific molecular targets and signaling processes. The molecular mechanism of lead toxicity remains poorly understood. The objective of this work was to characterize the effect of Pb(2+) on the structure and membrane-binding properties of C2α. C2α is a peripheral membrane-binding domain of Protein Kinase Cα (PKCα), which is a well-documented molecular target of lead. Using NMR and isothermal titration calorimetry (ITC) techniques, we established that C2α binds Pb(2+) with higher affinity than its natural cofactor, Ca(2+). To gain insight into the coordination geometry of protein-bound Pb(2+), we determined the crystal structures of apo and Pb(2+)-bound C2α at 1.9 and 1.5 Å resolution, respectively. A comparison of these structures revealed that the metal-binding site is not preorganized and that rotation of the oxygen-donating side chains is required for the metal coordination to occur. Remarkably, we found that holodirected and hemidirected coordination geometries for the two Pb(2+) ions coexist within a single protein molecule. Using protein-to-membrane Förster resonance energy transfer (FRET) spectroscopy, we demonstrated that Pb(2+) displaces Ca(2+) from C2α in the presence of lipid membranes through the high-affinity interaction with the membrane-unbound C2α. In addition, Pb(2+) associates with phosphatidylserine-containing membranes and thereby competes with C2α for the membrane-binding sites. This process can contribute to the inhibitory effect of Pb(2+) on the PKCα activity.

  13. Diffusive and convective transport through hollow fiber membranes for liver cell culture.

    Science.gov (United States)

    Curcio, E; De Bartolo, L; Barbieri, G; Rende, M; Giorno, L; Morelli, S; Drioli, E

    2005-05-25

    For an efficient membrane bioreactor design, transport phenomena determining the overall mass flux of metabolites, catabolites, cell regulatory factors, and immune-related soluble factors, need to be clarified both experimentally and theoretically. In this work, experiments and calculations aimed at discerning the simultaneous influence of both diffusive and convective mechanisms to the transport of metabolites. In particular, the transmembrane mass flux of glucose, bovine serum albumin (BSA), APO-transferrin, immunoglobulin G, and ammonia was experimentally measured, under pressure and concentration gradients, through high-flux microporous hydrophilic poly-ether-sulphone (PES-HFMs) and poly-sulphone hollow fiber membranes (PS-HFMs). These data were analyzed by means of a model based on the mechanism of capillary pore diffusion, assuming that solute spherical molecules pass through an array of solvent-filled cylindrical pores with a diffusive permeation corrected for friction and steric hindrances. Additionally, resistances to the mass transfer were taken into account. Convective permeation data were discussed in terms of morphological properties of the polymeric membranes, molecular Stokes radius, and solute-membrane interactions according to information given by contact angle measurements. The observed steady-state hydraulic permeance of PS-HFMs was 0.972 L/m2hmbar, about 15.6-fold lower than that measured for PES-HFMs (15.2 L/m2h); in general, PS-HFMs provided a significant hindrance to the transport of target species. Diffusion coefficients of metabolites were found to be similar to the corresponding values in water through PES-HFMs, but significantly reduced through PS-HFMs (D(Glucose)(Membrane)=2.8x10(-6)+/-0.6x10(-6)cm2/s, D(BSA)(Membrane)=6.4 x 10(-7)+/-1 x 10(-7)cm(/s, D(Apotransferrin)(Membrane)=2.3 x 10(-7)+/-0.25 x 10(-7)cm2/s).

  14. Suppression of FM-to-AM modulation by polarizing fiber front end for high-power lasers.

    Science.gov (United States)

    Qiao, Zhi; Wang, Xiaochao; Fan, Wei; Li, Xuechun; Jiang, Youen; Li, Rao; Huang, Canhong; Lin, Zunqi

    2016-10-10

    FM-to-AM modulation is an important effect in the front end of high-power lasers that influences the temporal profile. Various methods have been implemented in standard-fiber and polarization-maintaining (PM)-fiber front ends to suppress the FM-to-AM modulation. To analyze the modulation in the front end, a theoretical model is established and detailed simulations carried out that show that the polarizing (PZ) fiber, whose fast axis has a large loss, can successfully suppress the modulation. Moreover, the stability of the FM-to-AM modulation can be improved, which is important for the front end to obtain a stable output. To verify the model, a PZ fiber front end is constructed experimentally. The FM-to-AM modulation, without any compensation, is less than 4%, whereas that of the PM fiber front end with the same structure is nearly 20%. The stability of the FM-to-AM modulation depth is analyzed experimentally and the peak-to-peak and standard deviation (SD) are 2% and 0.38%, respectively, over 3 h. The experimental results agree with the simulation results and both prove that the PZ fiber front end can successfully suppress the FM-to-AM conversion. The PZ fiber front end is a promising alternative for improving the performance of the front end in high-power laser facilities.

  15. Hollow Fiber Flight Prototype Spacesuit Water Membrane Evaporator Design and Testing

    Science.gov (United States)

    Bue, Grant; Vogel, Matt; Makinen, Janice; Tsioulos, Gus

    2010-01-01

    The spacesuit water membrane evaporator (SWME) is being developed to perform thermal control for advanced spacesuits and to take advantage of recent advances in micropore membrane technology. This results in a robust heat-rejection device that is potentially less sensitive to contamination than is the sublimator. The Membrana Celgard X50-215 microporous hollow-fiber (HoFi) membrane was selected after recent extensive testing as the most suitable candidate among commercial alternatives for continued SWME prototype development. The current design was based on a previous design that grouped the fiber layers into stacks, which were separated by small spaces and packaged into a cylindrical shape. This was developed into a full-scale prototype consisting of 14,300 tube bundled into 30 stacks, each of which is formed into a chevron shape and separated by spacers and organized into three sectors of 10 nested stacks. The new design replaced metal components with plastic ones, and has a custom built flight like backpressure valve mounted on the side of the SWME housing to reduce backpressure when fully open. The spacers that provided separation of the chevron fiber stacks were eliminated. Vacuum chamber testing showed improved heat rejection as a function of inlet water temperature and water vapor backpressure compared with the previous design. Other tests pushed the limits of tolerance to freezing and showed suitability to reject heat in a Mars pressure environment with and without a sweep gas. Tolerance to contamination by constituents expected to be found in potable water produced by distillation processes was tested in a conventional way by allowing constituents to accumulate in the coolant as evaporation occurs. For this purpose, the SWME cartridge has endured an equivalent of 30 EVAs exposure and demonstrated minimal performance decline.

  16. Fusion Pore Diameter Regulation by Cations Modulating Local Membrane Anisotropy

    Directory of Open Access Journals (Sweden)

    Doron Kabaso

    2012-01-01

    Full Text Available The fusion pore is an aqueous channel that is formed upon the fusion of the vesicle membrane with the plasma membrane. Once the pore is open, it may close again (transient fusion or widen completely (full fusion to permit vesicle cargo discharge. While repetitive transient fusion pore openings of the vesicle with the plasma membrane have been observed in the absence of stimulation, their frequency can be further increased using a cAMP-increasing agent that drives the opening of nonspecific cation channels. Our model hypothesis is that the openings and closings of the fusion pore are driven by changes in the local concentration of cations in the connected vesicle. The proposed mechanism of fusion pore dynamics is considered as follows: when the fusion pore is closed or is extremely narrow, the accumulation of cations in the vesicle (increased cation concentration likely leads to lipid demixing at the fusion pore. This process may affect local membrane anisotropy, which reduces the spontaneous curvature and thus leads to the opening of the fusion pore. Based on the theory of membrane elasticity, we used a continuum model to explain the rhythmic opening and closing of the fusion pore.

  17. Cross-phase-modulation-induced instability in photonic-crystal fibers.

    Science.gov (United States)

    Serebryannikov, E E; Konorov, S O; Ivanov, A A; Alfimov, M V; Scalora, M; Zheltikov, A M

    2005-08-01

    Cross-phase-modulation-induced instability is identified as a significant mechanism for efficient parametric four-wave-mixing frequency conversion in photonic-crystal fibers. Fundamental-wavelength femtosecond pulses of a Cr, forsterite laser are used in our experiments to transform the spectrum of copropagating second-harmonic pulses of the same laser in a photonic-crystal fiber. Efficient generation of sidebands shifted by more than 80 THz with respect to the central frequency of the second harmonic is observed in the output spectrum of the probe field.

  18. Enhanced soliton-effect pulse compression by cross-phase modulation in optical fibers

    Institute of Scientific and Technical Information of China (English)

    曹文华; 刘颂豪

    2000-01-01

    A new method is proposed to enhance the soliton-effect compression of optical pulses. It consists of copropagating two optical pulses with close wavelengths in the anomalous group-velocity dispersion regime of single-mode fibers. Numerical simulations show that, as compared with the traditional single pulse compression method, cross-phase modulation can not only dramatically increase the compression ratio but also decrease the optimum fiber length. The effects of initial pulse-width mismatch, Raman self-scattering, and pulse walk-off on the pulse compression are also discussed.

  19. On the Theory of the Modulation Instability in Optical Fiber and Laser Amplifiers

    Energy Technology Data Exchange (ETDEWEB)

    Rubenchik, A M; Turitsyn, S K; Fedoruk, M P

    2010-11-03

    The modulation instability (MI) in optical fiber amplifiers and lasers with anomalous dispersion leads to CW beam breakup and the growth of multiple pulses. This can be both a detrimental effect, limiting the performance of amplifiers, and also an underlying physical mechanism in the operation of MI-based devices. Here we revisit the analytical theory of MI in fiber optical amplifiers. The results of the exact theory are compared with the previously used adiabatic approximation model, and the range of applicability of the latter is determined. The same technique is applicable to the study of spatial MI in solid state laser amplifiers and MI in non-uniform media.

  20. Amplification of Frequency-Modulated Similariton Pulses in Length-Inhomogeneous Active Fibers

    Directory of Open Access Journals (Sweden)

    I. O. Zolotovskii

    2012-01-01

    Full Text Available The possibility of an effective gain of the self-similar frequency-modulated (FM wave packets is studied in the length-inhomogeneous active fibers. The dynamics of parabolic pulses with the constant chirp has been considered. The optimal profile for the change of the group-velocity dispersion corresponding to the optimal similariton pulse amplification has been obtained. It is shown that the use of FM pulses in the active (gain and length-inhomogeneous optical fibers with the normal group-velocity dispersion can provide subpicosecond optical pulse amplification up to the energies higher than 1 nJ.

  1. Module design for MIEC membranes in OXYCOAL-AC

    Energy Technology Data Exchange (ETDEWEB)

    E.M. Pfaff; M. Zwick; S. Dabbarh; C. Broeckmann [RWTH Aachen University, Aachen (Germany)

    2009-07-01

    In world wide efforts processes are in development for coal or gas combustion with an additional capturing of CO{sub 2} exhaust gas for storage in the underground. Most efficiency is expected by burning in a nitrogen free atmosphere. The oxygen needed for the combustion shall be delivered by so called Oxygen Transport Membranes (OTM) in the combustion process. Perovskite type ceramics with mixed ionic and electronic conductivity at high temperatures can be used as membrane materials. With improving the oxygen ion conductivity other relevant material properties became critical in particular chemical stability and mechanical strength. The ceramic membranes must be joint gas tight to metal housings and work at 800 - 1000{sup o}C. Different concepts are under construction concerning the design of OTM reactors in tubular or planar structures. 14 refs., 11 figs., 6 tabs.

  2. Indole prevents Escherichia coli cell division by modulating membrane potential.

    Science.gov (United States)

    Chimerel, Catalin; Field, Christopher M; Piñero-Fernandez, Silvia; Keyser, Ulrich F; Summers, David K

    2012-07-01

    Indole is a bacterial signalling molecule that blocks E. coli cell division at concentrations of 3-5 mM. We have shown that indole is a proton ionophore and that this activity is key to the inhibition of division. By reducing the electrochemical potential across the cytoplasmic membrane of E. coli, indole deactivates MinCD oscillation and prevents formation of the FtsZ ring that is a prerequisite for division. This is the first example of a natural ionophore regulating a key biological process. Our findings have implications for our understanding of membrane biology, bacterial cell cycle control and potentially for the design of antibiotics that target the cell membrane.

  3. Modulation of Dendritic-Epithelial Cell Responses against Sphingomonas Paucimobilis by Dietary Fibers.

    Science.gov (United States)

    Bermudez-Brito, Miriam; Faas, Marijke M; de Vos, Paul

    2016-07-25

    Non-fermenting Gram-negative bacilli, such as Sphingomonas paucimobilis (S.paucimobilis), are among the most widespread causes of nosocomial infections. Up to now, no definitive guidelines exist for antimicrobial therapy for S. paucimobilis infections. As we have shown that some dietary fibers exhibit pronounced immune-regulatory properties, we hypothesized that specific immune active dietary fibers might modulate the responses against S. paucimobilis. We studied the immunomodulatory effects of dietary fibers against S. paucimobilis on cytokine release and maturation of human dendritic cells (DCs) in co-cultures of DCs and intestinal epithelial cells (IECs). S. paucimobilis infection resulted in increased release of pro-inflammatory cytokines and chemokines by DCs/IECs; these effects were strongly attenuated by specific dietary fibers. Chicory inulin, sugar beet pectin, and both starches had the strongest regulatory effects. IL-12 and TNF-α were drastically diminished upon exposure to chicory inulin and sugar beet pectin, or both starches. High-maize 260, was more effective in the reduction of chemokine release than the others fibers tested. In summary, chicory inulin, sugar beet pectin, High-maize 260, and Novelose 330 attenuate S. paucimobilis-induced cytokines. These results demonstrate that dietary fibers with a specific chemical composition can be used to manage immune responses against pathogens such as S. paucimobilis.

  4. Modulation of Dendritic-Epithelial Cell Responses against Sphingomonas Paucimobilis by Dietary Fibers

    Science.gov (United States)

    Bermudez-Brito, Miriam; Faas, Marijke M; de Vos, Paul

    2016-01-01

    Non-fermenting Gram-negative bacilli, such as Sphingomonas paucimobilis (S.paucimobilis), are among the most widespread causes of nosocomial infections. Up to now, no definitive guidelines exist for antimicrobial therapy for S. paucimobilis infections. As we have shown that some dietary fibers exhibit pronounced immune-regulatory properties, we hypothesized that specific immune active dietary fibers might modulate the responses against S. paucimobilis. We studied the immunomodulatory effects of dietary fibers against S. paucimobilis on cytokine release and maturation of human dendritic cells (DCs) in co-cultures of DCs and intestinal epithelial cells (IECs). S. paucimobilis infection resulted in increased release of pro-inflammatory cytokines and chemokines by DCs/IECs; these effects were strongly attenuated by specific dietary fibers. Chicory inulin, sugar beet pectin, and both starches had the strongest regulatory effects. IL-12 and TNF-α were drastically diminished upon exposure to chicory inulin and sugar beet pectin, or both starches. High-maize 260, was more effective in the reduction of chemokine release than the others fibers tested. In summary, chicory inulin, sugar beet pectin, High-maize 260, and Novelose 330 attenuate S. paucimobilis-induced cytokines. These results demonstrate that dietary fibers with a specific chemical composition can be used to manage immune responses against pathogens such as S. paucimobilis. PMID:27452116

  5. Optical feedback-induced light modulation for fiber-based laser ablation.

    Science.gov (United States)

    Kang, Hyun Wook

    2014-11-01

    Optical fibers have been used as a minimally invasive tool in various medical fields. However, due to excessive heat accumulation, the distal end of a fiber often suffers from severe melting or devitrification, leading to the eventual fiber failure during laser treatment. In order to minimize thermal damage at the fiber tip, an optical feedback sensor was developed and tested ex vivo. Porcine kidney tissue was used to evaluate the feasibility of optical feedback in terms of signal activation, ablation performance, and light transmission. Testing various signal thresholds demonstrated that 3 V was relatively appropriate to trigger the feedback sensor and to prevent the fiber deterioration during kidney tissue ablation. Based upon the development of temporal signal signatures, full contact mode rapidly activated the optical feedback sensor possibly due to heat accumulation. Modulated light delivery induced by optical feedback diminished ablation efficiency by 30% in comparison with no feedback case. However, long-term transmission results validated that laser ablation assisted with optical feedback was able to almost consistently sustain light delivery to the tissue as well as ablation efficiency. Therefore, an optical feedback sensor can be a feasible tool to protect optical fiber tips by minimizing debris contamination and delaying thermal damage process and to ensure more efficient and safer laser-induced tissue ablation.

  6. Role of 17 beta-estradiol on type IV collagen fibers volumetric density in the basement membrane of bladder wall.

    Science.gov (United States)

    de Fraga, Rogerio; Dambros, Miriam; Miyaoka, Ricardo; Riccetto, Cássio Luís Zanettini; Palma, Paulo César Rodrigues

    2007-10-01

    The authors quantified the type IV collagen fibers volumetric density in the basement membrane of bladder wall of ovariectomized rats with and without estradiol replacement. This study was conducted on 40 Wistar rats (3 months old) randomly divided in 4 groups: group 1, remained intact (control); group 2, submitted to bilateral oophorectomy and daily replacement 4 weeks later of 17 beta-estradiol for 12 weeks; group 3, sham operated and daily replacement 4 weeks later of sesame oil for 12 weeks; and group 4, submitted to bilateral oophorectomy and killed after 12 weeks. It was used in immunohistochemistry evaluation using type IV collagen polyclonal antibody to stain the fibers on paraffin rat bladder sections. The M-42 stereological grid system was used to analyze the fibers. Ovariectomy had an increase effect on the volumetric density of the type IV collagen fibers in the basement membrane of rat bladder wall. Estradiol replacement in castrated animals demonstrated a significative difference in the stereological parameters when compared to the castrated group without hormonal replacement. Surgical castration performed on rats induced an increasing volumetric density of type IV collagen fibers in the basement membrane of rats bladder wall and the estradiol treatment had a significant effect in keeping a low volumetric density of type IV collagen fibers in the basement membrane of rats bladder wall.

  7. Hybrid Anion Exchange Hollow Fiber Membrane for Delivery of Ionic Drugs

    Directory of Open Access Journals (Sweden)

    Na Wang

    2012-01-01

    Full Text Available Hybrid anion exchange hollow fiber membranes (HAEHFMs based on bromomethylated poly(2,6-dimethyl-1,4-phenylene oxide (BPPO are proposed as potential drug carriers for four anionic model drugs, including the sodium salts of benzoate (NaBS, salicylate (NaSA, meta-amino salicylate (NaMAS, and loxoprofen (NaLS. The results of the static loading and release experiments suggest that electrostatic interaction, hydrogen bonding, and hydrophobic interaction are the main interaction patterns between the membrane and the drugs. And they are directly influenced by the external phase conditions and the drug physicochemical characteristics, such as structure, molecular weight, dissociation (pKa, and hydrogen bonding capability. Among the four different drugs, NaSA and NaMAS appear to be the most suitable for controlled release by the HAEHFM due to their excellent adsorption/release behaviors.

  8. Full-Scale Hollow Fiber Spacesuit Water Membrane Evaporator Prototype Development and Testing for Advanced Spacesuits

    Science.gov (United States)

    Bue, Grant; Trevino, Luis; Tsioulos, Gus; Mitchell, Keith; Dillon, Paul; Weaver, Gregg

    2009-01-01

    The spacesuit water membrane evaporator (SWME) is being developed to perform the thermal control function for advanced spacesuits to take advantage of recent advances in micropore membrane technology in providing a robust heat-rejection device that is potentially less sensitive to contamination than is the sublimator. Principles of a sheet membrane SWME design were demonstrated using a prototypic test article that was tested in a vacuum chamber at JSC in July 1999. The Membrana Celgard X50-215 microporous hollow fiber (HoFi) membrane was selected after recent contamination tests as the superior candidate among commercial alternatives for HoFi SWME prototype development. Although a number of design variants were considered, one that grouped the fiber layers into stacks, which were separated by small spaces and packaged into a cylindrical shape, was deemed best for further development. An analysis of test data showed that eight layer stacks of the HoFi sheets that had good exposure on each side of the stack would evaporate water with high efficiency. A design that has 15,000 tubes, with 18 cm of exposed tubes between headers has been built and tested that meets the size, weight, and performance requirements of the SWME. This full-scale prototype consists of 30 stacks, each of which are formed into a chevron shape and separated by spacers and organized into three sectors of ten nested stacks. Testing has been performed to show contamination resistance to the constituents expected to be found in potable water produced by the distillation processes. Other tests showed the sensitivity to surfactants.

  9. Operation Characteristics of Treating Surface Water with Polyvinylchloride Hollow Fiber Ultrafiltration Membrane

    Institute of Scientific and Technical Information of China (English)

    GUO Xiaoyan; ZHANG Zhenjia; FANG Lin; SU Liguo

    2006-01-01

    A pilot plant study on a polyvinylchloride hollow fiber ultrafiltration membrane process was conducted for treating surface water.The membrane system was operated in the dead-end filtration mode under different constant permeate fluxes.The results show that the optimized operation ( transmembrane pressure≤0.1 Mpa,filtration time≤30 min) with a hydraulic cleaning (30 s) and a chemical cleaning (30 min,the chemical cleaning was performed after 16 cycles of filtration ) en ures a quite steady flux (1 100 L/(m2·h · Mpa)) and good permeate quality (turbidity <0.1NTU ).A full-scale plant can be suggested to operate with a mixed strategy of constant permeate flux mode (transmembrane pressure ≤0.1 Mpa) and constant transmembrane pressure mode.When the temperature of raw water becomes below 5 ℃,a constant transmembrane pressure mode should be used; otherwise a constant permeate flux mode (transmembrane pressure ≤ 0.1 Mpa) can be operated.In this way,irreversible fouling of ultrafiltration membrane can be minimized to keep a stable flux and make the life of membrane longer.

  10. Fiber-optic project-fringe interferometry with sinusoidal phase modulating system

    Science.gov (United States)

    Zhang, Fukai; Duan, Fajie; Lv, Changrong; Duan, Xiaojie; Bo, En; Feng, Fan

    2013-06-01

    A fiber-optic sinusoidal phase-modulating (SPM) interferometer for fringe projection is presented. The system is based on the SPM technique and makes use of the Mach-Zehnder interferometer structure and Young's double pinhole interference principle to achieve interference fringe projection. A Michelson interferometer, which contains the detection of Fresnel reflection on its fiber end face and interference at one input port of a 3 dB coupler, is utilized to achieve feedback precise control of the fringe phase, which is sensitive to phase drifting produced by the nature of the fiber. The phase diversity for the closed-loop SPM system can be real-time measured with a precision of 3 mrad. External disturbances mainly caused by temperature fluctuations can be reduced to 57 mrad for the fringe map. The experimental results have shown the usefulness of the system.

  11. Prospective association between alcohol intake and hormone-dependent cancer risk: modulation by dietary fiber intake.

    Science.gov (United States)

    Chhim, Anne-Sophie; Fassier, Philippine; Latino-Martel, Paule; Druesne-Pecollo, Nathalie; Zelek, Laurent; Duverger, Lucie; Hercberg, Serge; Galan, Pilar; Deschasaux, Mélanie; Touvier, Mathilde

    2015-07-01

    Alcohol intake is associated with increased circulating concentrations of sex hormones, which in turn may increase hormone-dependent cancer risk. This association may be modulated by dietary fiber intake, which has been shown to decrease steroid hormone bioavailability (decreased blood concentration and increased sex hormone-binding globulin concentration). However, this potential modulation has not been investigated in any prospective cohort. Our objectives were to study the relation between alcohol intake and the risk of hormone-dependent cancers (breast, prostate, ovarian, endometrial, and testicular) and to investigate whether dietary fiber intake modulated these associations. This prospective observational analysis included 3771 women and 2771 men who participated in the Supplémentation en Vitamines et Minéraux Antioxydants study (1994-2007) and completed at least 6 valid 24-h dietary records during the first 2 y of follow-up. After a median follow-up of 12.1 y, 297 incident hormone-dependent cancer cases, including 158 breast and 123 prostate cancers, were diagnosed. Associations were tested via multivariate Cox proportional hazards models. Overall, alcohol intake was directly associated with the risk of hormone-dependent cancers (tertile 3 vs. tertile 1: HR: 1.36; 95% CI: 1.00, 1.84; P-trend = 0.02) and breast cancer (HR: 1.70; 95% CI: 1.11, 2.61; P-trend = 0.04) but not prostate cancer (P-trend = 0.3). In stratified analyses (by sex-specific median of dietary fiber intake), alcohol intake was directly associated with hormone-dependent cancer (tertile 3 vs. tertile 1: HR: 1.76; 95% CI: 1.10, 2.82; P-trend = 0.002), breast cancer (HR: 2.53; 95% CI: 1.30, 4.95; P-trend = 0.02), and prostate cancer (HR: 1.37; 95% CI: 0.65, 2.89; P-trend = 0.02) risk among individuals with low dietary fiber intake but not among their counterparts with higher dietary fiber intake (P-trend = 0.9, 0.8, and 0.6, respectively). The P-interaction between alcohol and dietary fiber

  12. Graphene-coated hollow fiber membrane as the cathode in anaerobic electrochemical membrane bioreactors – Effect of configuration and applied voltage on performance and membrane fouling

    KAUST Repository

    Werner, Craig M.

    2015-12-22

    Electrically conductive, graphene-coated hollow-fiber porous membranes were used as cathodes in anaerobic electrochemical membrane bioreactors (AnEMBRs) operated at different applied voltages (0.7 V and 0.9 V) using a new rectangular reactor configuration, compared to a previous tubular design (0.7 V). The onset of biofouling was delayed and minimized in rectangular reactors operated at 0.9 V, compared to those at 0.7 V due to higher rates of hydrogen production. Maximum transmembrane pressures for the rectangular reactor were only 0.10 bar (0.7 V) or 0.05 bar (0.9 V) after 56 days of operation, compared to 0.46 bar (0.7 V) for the tubular reactor after 52 days. The thickness of the membrane biofouling layer was approximately 0.4 µm for rectangular reactors and 4 µm for the tubular reactor. Higher permeate quality (TSS = 0.05 mg/L) was achieved in the rectangular AnEMBR than the tubular AnEMBR (TSS = 17 mg/L), likely due to higher current densities that minimized the accumulation of cells in suspension. These results show that the new rectangular reactor design, which had increased rates of hydrogen production, successfully delayed the onset of cathode biofouling and improved reactor performance.

  13. A theoretical study of transient stimulated Brillouin scattering in optical fibers seeded with phase-modulated light.

    Science.gov (United States)

    Zeringue, Clint; Dajani, Iyad; Naderi, Shadi; Moore, Gerald T; Robin, Craig

    2012-09-10

    Beam combining of phase-modulated kilowatt fiber amplifiers has generated considerable interest recently. We describe in the time domain how stimulated Brillouin scattering (SBS) is generated in an optical fiber under phase-modulated laser conditions, and we analyze different phase modulation techniques. The temporal and spatial evolutions of the acoustic phonon, laser, and Stokes fields are determined by solving the coupled three-wave interaction system. Numerical accuracy is verified through agreement with the analytical solution for the un-modulated case and through the standard photon conservation relation for counter-propagating optical fields. As a test for a modulated laser, a sinusoidal phase modulation is examined for a broad range of modulation amplitudes and frequencies. We show that, at high modulation frequencies, our simulations agree with the analytical results obtained from decomposing the optical power into its frequency components. At low modulation frequencies, there is a significant departure due to the appreciable cross talk among the laser and Stokes sidebands. We also examine SBS suppression for a white noise source and show significant departures for short fibers from analytically derived formulas. Finally, SBS suppression through the application of pseudo-random bit sequence modulation is examined for various patterns. It is shown that for a fiber length of 9 m the patterns at or near n=7 provide the best mitigation of SBS with suppression factors approaching 17 dB at a modulation frequency of 5 GHz.

  14. A fiber-coupled 9xx module with tap water cooling

    Science.gov (United States)

    Schleuning, D.; Anthon, D.; Chryssis, A.; Ryu, G.; Liu, G.; Winhold, H.; Fan, L.; Xu, Z.; Tanbun-Ek, T.; Lehkonen, S.; Acklin, B.

    2016-03-01

    A novel, 9XX nm fiber-coupled module using arrays of highly reliable laser diode bars has been developed. The module is capable of multi-kW output power in a beam parameter product of 80 mm-mrad. The module incorporates a hard-soldered, isolated stack package compatible with tap-water cooling. Using extensive, accelerated multi-cell life-testing, with more than ten million device hours of test, we have demonstrated a MTTF for emitters of >500,000 hrs. In addition we have qualified the module in hard-pulse on-off cycling and stringent environmental tests. Finally we have demonstrated promising results for a next generation 9xx nm chip design currently in applications and qualification testing

  15. Tailored bars at 976 nm for high-brightness fiber-coupled modules

    Science.gov (United States)

    Kissel, Heiko; Wolf, Paul; Bachmann, Alexander; Lauer, Christian; König, Harald; Tomm, Jens W.; Köhler, Bernd; Strauß, Uwe; Biesenbach, Jens

    2017-02-01

    In 2007, DILAS proposed the approach to tailor the output beam characteristics of laser diodes to match the required beam quality of a desired target fiber, thus, drastically simplifying the coupling optics to basically only fast and slow axis collimation lenses. Over the last years, we developed and improved this tailored bar (T-Bar) concept together with the tooling for fully automated mass production of fiber-coupled T-Bar modules for fiber laser pumping as well as for direct applications. We present results on the improvement of T-Bars tailored for optimized coupling into fibers with a diameter of 200 μm with NA 0.22 corresponding to a beam parameter product of 22 mm·mrad. Cost efficient coupling to this fiber requires a tailored beam parameter product smaller than 15.5 mm·mrad in slow axis direction corresponding to a slow axis beam divergence of 7° (full angle, 95% power content) for five 100 μm wide emitters. The improved T-Bars fulfil this requirement up to an output power of 52 W with a brightness of 3.1 W/mm·mrad and a power conversion efficiency achieving 69%. This progress in the T-Bar performance together with modifications in the module design led to the increase of the reliable output power from 135 W in 2009 to 360 W in 2017 for a T-Bar module with one baseplate. We will also give a review of the main development steps and further R and D improvements.

  16. Q-switched all-fiber laser based on magnetostriction modulation of a Bragg grating.

    Science.gov (United States)

    Pérez-Millán, P; Díez, A; Andrés, M; Zalvidea, D; Duchowicz, R

    2005-06-27

    We report an actively Q-switched all-fiber laser based on magnetostriction modulation of a Bragg grating. The laser employs a pair of Bragg gratings as reflective mirrors, one of which is bonded to a magnetostrictive element. Lengthening of the magnetostrictive element when a magnetic field is applied shifts the Bragg wavelength of the grating, allowing control of the Q-factor of the cavity and, thus, performing active Q-switching. The magnetostrictive modulator is small, compact and requires less than 300 mW electrical drive power. Using erbium-doped fiber and a maximum pump power of 120 mW, Q-switch pulses of more than 1 W peak power were obtained, with a pulse repetition rate that can be continuously varied from 1 Hz to 125 kHz.

  17. Photonic packaging sourcebook fiber-chip coupling for optical components, basic calculations, modules

    CERN Document Server

    Fischer-Hirchert, Ulrich H P

    2015-01-01

    This book serves as a guide on photonic assembly techniques. It provides an overview of today's state-of-the-art technologies for photonic packaging experts and professionals in the field. The text guides the readers to the practical use of optical connectors. It also assists engineers to find a way to an effective and inexpensive set-up for their own needs. In addition, many types of current industrial modules and state-of-the-art applications from single fiber to multi fiber are described in detail. Simulation techniques such as FEM, BPM and ray tracing are explained in depth. Finally, all recent reliability test procedures for datacom and telecom modules are illustrated in combination with related standardization aspects.

  18. Q-switched all-fiber laser based on magnetostriction modulation of a Bragg grating

    Science.gov (United States)

    Pérez-Millán, P.; Díez, A.; Andrés, M. V.; Zalvidea, D.; Duchowicz, R.

    2005-06-01

    We report an actively Q-switched all-fiber laser based on magnetostriction modulation of a Bragg grating. The laser employs a pair of Bragg gratings as reflective mirrors, one of which is bonded to a magnetostrictive element. Lengthening of the magnetostrictive element when a magnetic field is applied shifts the Bragg wavelength of the grating, allowing control of the Q-factor of the cavity and, thus, performing active Q-switching. The magnetostrictive modulator is small, compact and requires less than 300 mW electrical drive power. Using erbium-doped fiber and a maximum pump power of 120 mW, Q-switch pulses of more than 1 W peak power were obtained, with a pulse repetition rate that can be continuously varied from 1 Hz to 125 kHz.

  19. Modulated Pulses Based High Spatial Resolution Distributed Fiber System for Multi-Parameter Sensing

    CERN Document Server

    Zhang, Jingdong; Zhou, Huan; Li, Yang; Liu, Min; Huang, Wei

    2016-01-01

    We demonstrate a hybrid distributed fiber sensing system for multi-parameter detection. The integration of phase-sensitive optical time domain reflectometry ({\\Phi}-OTDR) and Brillouin optical time domain reflectometry (B-OTDR) enables measurement of vibration, temperature and strain. Exploiting the fast changing property of vibration and the static property of temperature and strain, the laser pulse width and intensity are modulated and then injected into the single-mode sensing fiber proportionally, so that the three concerned parameters can be extracted simultaneously by only one photo-detector and data acquisition channel. Combining with advanced data processing methods, the modulation of laser pulse brings additional advantages because of trade and balance between the backscattering light power and nonlinear effect noise, which enhances the signal-to-noise ratio, and enables sub-meter level spatial resolution together with long sensing distance. The proposed method realizes up to 4.8 kHz vibration sensin...

  20. Intensity-modulated relative humidity sensing with polyvinyl alcohol coating and optical fiber gratings.

    Science.gov (United States)

    Yang, Jingyi; Dong, Xinyong; Ni, Kai; Chan, Chi Chu; Shun, Perry Ping

    2015-04-01

    A relative humidity (RH) sensor in reflection mode is proposed and experimentally demonstrated by using a polyvinyl alcohol (PVA)-coated tilted-fiber Bragg grating (TFBG) cascaded by a reflection-band-matched chirped-fiber Bragg grating (CFBG). The sensing principle is based on the RH-dependent refractive index of the PVA coating, which modulates the transmission function of the TFBG. The CFBG is properly designed to reflect a broadband of light spectrally suited at the cladding mode resonance region of the TFBG, thus the reflected optical signal passes through and is modulated by the TFBG again. As a result, RH measurements with enhanced sensitivity of ∼1.80  μW/%RH are realized and demodulated in the range from 20% RH to 85% RH.

  1. Modulation of membrane potential by an acetylcholine-activated potassium current in trout atrial myocytes

    DEFF Research Database (Denmark)

    Molina, C.E.; Gesser, Hans; Llach, A.

    2007-01-01

    mV from 4.3 pA/pF to 27 pA/pF with an EC50 of 45 nM in atrial myocytes. Moreover, 3 nM ACh increased the slope conductance of Im fourfold, shifted its reversal potential from -78 ± 3 to -84 ± 3 mV, and stabilized the resting membrane potential at -92 ± 4 mV. ACh also shortened the action potential...... hypothesized that this is at least partly due to a small slope conductance of Im around the resting membrane potential in atrial myocytes. In accordance with this hypothesis, the slope conductance of Im was about sevenfold smaller in atrial than in ventricular myocytes. Interestingly, ACh increased Im at -120...... of an inwardly rectifying K+ current can modulate the membrane potential in the trout atrial myocytes and stabilize the resting membrane potential. teleost heart; IK,ACh; cholinergic modulation; action potential...

  2. A Novel Temperature-Compensated, Intensity-Modulated Fiber Bragg Grating Sensor System

    Institute of Scientific and Technical Information of China (English)

    Xin-Yong Dong; Hwa-Yaw Tam

    2008-01-01

    An intensity-modulated, fiber Bragg grating (FBG) sensor system based on radio-frequency (RF) signal measurement is presented. The RF signal is generated at a photodetector by two modulated optical signals reflected from the sensing FBG and a reference one. Bragg wavelength shift of the sensing FBG changes intensity of the RF signal by changing phase difference between the two optical signals, with temperature effect being compensated automatically by the reference FBG. Strain measurement with a maximum sensitivity of -0.34 μV/με has been achieved.

  3. CATV/radio-on-fiber transport system based on direct modulation

    Science.gov (United States)

    Tzeng, Shah-Jye

    2006-03-01

    A directly modulated CATV/radio-on-fiber (ROF) transport system based on external light injection technique, optical single sideband (SSB) filter, and RF amplifier predistorter is proposed and demonstrated. To the best of my knowledge, it is the first time to transmit CATV and ROF signals simultaneously in a directly modulated form. Good performances of carrier-to-noise ratio (CNR), composite second order (CSO) and composite triple beat (CTB) were obtained for CATV band; and low third order intermodulation distortion to carrier ratio (IMD3/C), and bit error rate (BER) values were achieved for ROF application.

  4. Stimulated Raman scattering microscopy by Nyquist modulation of a two-branch ultrafast fiber source.

    Science.gov (United States)

    Riek, Claudius; Kocher, Claudius; Zirak, Peyman; Kölbl, Christoph; Fimpel, Peter; Leitenstorfer, Alfred; Zumbusch, Andreas; Brida, Daniele

    2016-08-15

    A highly stable setup for stimulated Raman scattering (SRS) microscopy is presented. It is based on a two-branch femtosecond Er:fiber laser operating at a 40 MHz repetition rate. One of the outputs is directly modulated at the Nyquist frequency with an integrated electro-optic modulator (EOM). This compact source combines a jitter-free pulse synchronization with a broad tunability and allows for shot-noise limited SRS detection. The performance of the SRS microscope is illustrated with measurements on samples from material science and cell biology.

  5. Enhanced nonlinear spectral compression in fiber by external sinusoidal phase modulation

    Science.gov (United States)

    Boscolo, S.; Mouradian, L. Kh; Finot, C.

    2016-10-01

    We propose a new, simple approach to enhance the spectral compression process arising from nonlinear pulse propagation in an optical fiber. We numerically show that an additional sinusoidal temporal phase modulation of the pulse enables efficient reduction of the intensity level of the side lobes in the spectrum that are produced by the mismatch between the initial linear negative chirp of the pulse and the self-phase modulation-induced nonlinear positive chirp. Remarkable increase of both the extent of spectrum narrowing and the quality of the compressed spectrum is afforded by the proposed approach across a wide range of experimentally accessible parameters.

  6. Silicon carbide hollow fiber membranes: obtainment and characterization; Membranas de fibra oca de carbeto de silicio: obtencao e caracterizacao

    Energy Technology Data Exchange (ETDEWEB)

    Oliveira, S.S.L.; Ferreira, R.S.B.; Araujo, B.A.; Medeiros, K.M.; Lucena, H.L.; Araujo, E.M., E-mail: sandriely_sonaly@hotmail.com [Universidade Federal de Campina Grande (UFCG), PB (Brazil). Departamento de Engenharia de Materiais

    2016-07-01

    Silicon carbide is a promising material for the production of membranes due to its high melting temperature, thermal shock resistance, excellent mechanical and chemical stability. So, this study aims to characterize silicon carbide membranes in order to apply them in the separation of oil-water. A solution (SiC + PES + 1-Methyl- 2-Pyrrolidone) and through the extrusion technique by immersion precipitation membranes were obtained with hollow fiber geometry was prepared. And then sintered at 1500 ° C. For the characterization analyzes were made XRD, FTIR and SEM to evaluate the morphology and composition of the membranes obtained before and after sintering. (author)

  7. Response surface methodology to evaluation the recovery of amylases by hollow fiber membrane

    Directory of Open Access Journals (Sweden)

    João Baptista Severo Júnior

    2007-07-01

    Full Text Available This work aimed to study the pH and the transmembrane pressure effects during the recovery of alpha and beta amylases enzymes from corn malt (Zea mays by hollow fiber membrane. The optimal condition was obtained for a statistical model, established by response surface methodology (RSM. The response surface analysis showed that the best operation condition for amylolitics enzymes recovery by hollow fiber membrane was 0.05 bar and pH 5.00, while the enzymes were purified about of 26 times.Este trabalho objetivou estudar o efeito do pH e da pressão trans-membrana durante a recuperação das enzimas alfa e beta amilases do malte de milho (Zea mays por membranas de fibras ocas, a obtenção das condições ótimas foi feita por um modelo estatístico, estabelecido pela metodologia de superfície de resposta (RSM. A análise da superfície de resposta mostrou que as melhores condições operacionais para a recuperação das enzimas amiloliticas por membranas de fibras ocas foi 0,05 bar e pH 5,00; onde as enzimas foram purificadas cerca de 26 vezes.

  8. Modulation of action potential trains in rabbit saphenous nerve unmyelinated fibers.

    Science.gov (United States)

    Zhu, Zhi-Ru; Liu, Yi-Hui; Ji, Wei-Gang; Duan, Jian-Hong; Hu, San-Jue

    2013-01-01

    Usually, the main axon is assumed to faithfully conduct action potentials (APs). Recent data have indicated that neural processing can occur along the axonal path. However, the patterns and mechanisms of temporal coding are not clear. In the present study, single fiber recording was used to analyze activity-dependent modulation of AP trains in the main axons of C fibers in the rabbit saphenous nerve. Trains of 5 superthreshold electrical pulses at interstimulus intervals of 20 or 50 ms were applied to the nerve trunk for 200 s. The interspike intervals (ISIs) for these trains were compared to the input interstimulus intervals. Three basic types of C fibers were observed in response to repeated stimuli: first, the ISI between the first and second AP (ISI1-2) of type 1 was longer than the interstimulus interval; second, the ISI1-2 of type 2 showed wavelike fluctuations around the interstimulus interval, and third, the ISI1-2 of type 3 exhibited shorter intervals for a long period. Furthermore, both 4-aminopyridine-sensitive potassium and hyperpolarization-activated cation currents were involved in the modulation of ISI1-2 of train pulses. These data provide new evidence that multiple modes of neural conduction can occur along the main axons of C fibers.

  9. Gas-liquid mass transfer in a cross-flow hollow fiber module : Analytical model and experimental validation

    NARCIS (Netherlands)

    Dindore, V. Y.; Versteeg, G. F.

    2005-01-01

    The cross-flow operation of hollow fiber membrane contactors offers many advantages and is preferred over the parallel-flow contactors for gas-liquid mass transfer operations. However, the analysis of such a cross-flow membrane gas-liquid contactor is complicated due to the change in concentrations

  10. Isolation and characterization of a thylakoid membrane module showing partial light and dark reactions.

    Science.gov (United States)

    Dani, Diksha Narhar; Sainis, Jayashree Krishna

    2005-05-15

    A functional thylakoid membrane module of photosynthesis was isolated from cell free extracts of Anacystis nidulans by stepwise sequential ultracentrifugation. The thylakoid membrane fractions sedimenting at 40,000 x g, followed by 90,000 x g and finally at 150,000 x g were collected. These fractions had all the components of electron transport chain, ATP synthase, phycobiliproteins, ferredoxin-NADP reductase but no ferredoxin. Five sequential enzymes of Calvin cycle viz phosphoriboisomerase, phosphoribulokinase, RuBP carboxylase, 3-PGA kinase and glyceraldehyde-3-phosphate dehydrogenase were found to be associated with thylakoid membranes. Among the three different thylakoid fractions, the 150,000 x g fraction showed highest activities of these enzymes and also higher rate of whole chain electron transport activity on chlorophyll basis. An important finding was that the 150,000 x g fraction showed appreciably higher rate of R-5-P+ADP+Pi dependent CO2 fixation in light compared to the other two fractions, indicating the efficiency of this fraction in utilizing ATP for Calvin cycle. This thylakoid membrane fraction represents a fully functional module exhibiting a synchronized system of light and dark reactions of photosynthesis. Most of the components of this module remained together even after sucrose density gradient centrifugation. This is the first report on the isolation of a photosynthetic module involving membrane and soluble proteins.

  11. Range Resolved CO2 Atmospheric Backscattering Measurements Using Fiber Lasers and RZPN Code Modulation

    Science.gov (United States)

    Burris, John

    2011-01-01

    We report the use of a return-to- zero (RZPN) pseudo noise modulation technique for making range resolved measurements of CO2 within the planetary boundary layer (PBL) using commercial, off-the-shelf, components. Conventional, range resolved, DIAL measurements require laser pulse widths that are significantly shorter than the desired spatial resolution and necessitate using pulses whose temporal spacing is such that scattered returns from only a single pulse are observed by the receiver at any one time (for the PBL pulse separations must be greater than approximately 20 microseconds). This imposes significant operational limitations when using currently available fiber lasers because of the resulting low duty cycle (less than approximately 0.0005) and consequent low average laser output power. The RZPN modulation technique enables a fiber laser to operate at much higher duty cycles (approaching 0.04) thereby more effectively utilizing the amplifier's output. This increases the counts received by approximately two orders of magnitude. Our approach involves employing two distributed feedback lasers (DFB), each modulated by a different RPZN code, whose outputs are then amplified by a CW fiber amplifier. One laser is tuned to a CO2 absorption line; the other operates offline thereby permitting the simultaneous acquisition of both on and offline signals using independent RZPN codes. This minimizes the impact of atmospheric turbulence on the measurement. The on and offline signals are retrieved by deconvolving the return signal using the appropriate kernels.

  12. THE ROLE OF POROUS MEDIA IN MODELING FLUID FLOW WITHIN HOLLOW FIBER MEMBRANES OF THE TOTAL ARTIFICIAL LUNG

    OpenAIRE

    2010-01-01

    A numerical study was conducted to analyze fluid flow within hollow fiber membranes of the artificial lungs. The hollow fiber bundle was approximated using a porous media model. In addition, the transport equations were solved using the finite-element formulation based on the Galerkin method of weighted residuals. Comparisons with previously published work on the basis of special cases were performed and found to be in excellent agreement. A Newtonian viscous fluid model for the blood was use...

  13. Radio over fiber link with adaptive order n‐QAM optical phase modulated OFDM and digital coherent detection

    DEFF Research Database (Denmark)

    Arlunno, Valeria; Borkowski, Robert; Guerrero Gonzalez, Neil

    2011-01-01

    Successful digital coherent demodulation of asynchronous optical phase‐modulated adaptive order QAM (4, 16, and 64) orthogonal frequency division multiplexing signals is achieved by a single reconfigurable digital receiver after 78 km of optical deployed fiber transmission....

  14. PREPARATION OF ASYMMETRIC POLYETHERKETONE FLAT AND HOLLOW FIBER MEMBRANES FOR GAS SEPARATION USING ACETIC ACID BASED COAGULANTS

    Institute of Scientific and Technical Information of China (English)

    Ji-ping Yang; Philip J. Brown

    2008-01-01

    Membranes for gas separation have developed significantly in the last twenty years, however, there is still a need for high temperature and chemically resistant membranes that exhibit good selectivity and gas permeability. Our study examines the fundamental properties of polyetherketone (PEK, a thermally stable and chemically resistant polymer)membranes prepared using concentrated sulphuric acid (98% H2SO4) as the solvent. Non-solvents used in the work included acetic acid, ethanol, methanol, glycerol, and water. The concentration of the polymer solutions was chosen to be 20%. The membrane structures were examined using SEM, and the gas separation properties were measured using a lab-scale test rig.The results show that formation and control of membrane structures are complicated, and many preparation parameters affect membrane morphology and performance. Using appropriate conditions skinned sponge-like structured hollow fiber membranes could be made from PEK by using acetic acid as the internal coagulant. PEK hollow fibers spun from 20%PEK/H2SO4 solutions with 50% aqueous acetic acid as internal coagulant had selectivity for hydrogen/methane of around 40, implying a solution diffusion separation mechanism for gas separation without the need for fiber coating or after post-treatments.

  15. Transport of Indium, Gallium and Thallium Metal Ions Through Chromatographic Fiber Supported Solid Membrane in Acetylacetone Containing Mixed Solvents

    Institute of Scientific and Technical Information of China (English)

    Abaji Gaikwad

    2011-01-01

    The transport of metal ions of indium, gallium and thallium from source solution to receiving phase through the chromatographic fiber supported solid membrane in the acetylacetone (HAA) containing mixed solvent system has been explored. The fibers supported solid membranes were prepared with chemical synthesis from cellulose fibers and citric acid with the carboxylic acid ion exchange groups introduced. The experimental variables, such as concentration of metal ions (10^-2 to 10^-4 mol.L^-1) in the source solution, mixed solvent composition [for exampl, e, acetylacetone, (2,4-pentanedione), (HAA) 20% (by volume), 1,4-dioxane 10% to 60% and HC1 0.25 to 2 mol.L^-1] in the receiving phase and stirring speed (50-130 r.min ) of the bulk source and receiving phase, were explored. The efficiency of mixed solvents for the transport of metal ions from the source to receiving phase through the fiber supported solid membrane was evaluated. The combined ion exchange solvent extraction (CIESE) was observed effective for the selective transport of thallium, indium and gallium metal ions through fiber supported solid membrane in mixed solvents. The oxonium salt formation in the receiving phase enhances thallium, indium and gallium metal ion transport through solid membrane phase. The selective transport of thallium metal ions from source phase was observed from indium and gallium metal ions in the presence of hydrochloric acid in organic solvents in receiving phase. The separation of thallium metal ions from the binary mixtures of Be(II), Ti(IV), AI(III) Ca(II), Mg(II), K (I), La(III) and Y(III) was carried out in the mixed solvent system using cellulose fiber supported solid membrane.

  16. Mathematical model analysis on the enhancement of aeration efficiency using ladder-type flat membrane module forms in the Submerged Membrane Bio-reactor(SMBR)

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    The cross-flow shearing action produced from the inferior aeration in the Submerged Membrane Bio-reactor(SMBR) is an effective way to further improve anti-fouling effects of membrane modules.Based on the widely-applied vertical structure of flat membrane modules,improvements are made that ladder-type flat membrane structure is designed with a certain inclined angle θ so that the cross-flow velocity of bubble near the membrane surface can be held,and the intensity and times of elastic colli-sion between bubbles and membrane surface can be increased.This can improve scouring action of membrane surface on aeration and reduce energy consumption of strong aeration in SMBR.By de-ducing and improving the mathematics model of collision between bubble and vertical flat put forward by Vries,the relatively suitable incline angle θ under certain aeration place and in certain size rang of bubble can be obtained with the computer iterative calculation technology.Finally,for many groups of ladder-type flat membrane in parallel placement in the practical application of SMBR,some sugges-tions are offered:the interval distance of membrane modules is 8―15 mm,and aeration should be op-erated at 5―7 mm among membrane modules,and the optimal design angle of trapeziform membrane is 1.7°―2.5°.

  17. Development of Polysulfone Hollow Fiber Porous Supports for High Flux Composite Membranes: Air Plasma and Piranha Etching

    Directory of Open Access Journals (Sweden)

    Ilya Borisov

    2017-02-01

    Full Text Available For the development of high efficiency porous supports for composite membrane preparation, polysulfone (PSf hollow fiber membranes (outer diameter 1.57 mm, inner diameter 1.12 mm were modified by air plasma using the low temperature plasma treatment pilot plant which is easily scalable to industrial level and the Piranha etch (H2O2 + H2SO4. Chemical and plasma modification affected only surface layers and did not cause PSf chemical structure change. The modifications led to surface roughness decrease, which is of great importance for further thin film composite (TFC membranes fabrication by dense selective layer coating, and also reduced water and ethylene glycol contact angle values for modified hollow fibers surface. Furthermore, the membranes surface energy increased two-fold. The Piranha mixture chemical modification did not change the membranes average pore size and gas permeance values, while air plasma treatment increased pore size 1.5-fold and also 2 order enhanced membranes surface porosity. Since membranes surface porosity increased due to air plasma treatment the modified membranes were used as efficient supports for preparation of high permeance TFC membranes by using poly[1-(trimethylsilyl-1-propyne] as an example for selective layer fabrication.

  18. Effect of higher order non-linearity in frequency variation of self-phase modulation in optical fiber communication

    Institute of Scientific and Technical Information of China (English)

    Abhijit Sinha; Sourangshu Mukhopadhyay

    2004-01-01

    In optical soliton propagation through a single mode optical fiber,it is established that self-phase mod ulation is maintained by the third order non-linearity of the silica-based glass material of the fiber.In this paper we show that the fifth order non-linearity has also some contribution in frequency variation of self-phase modulation.

  19. High-throughput hydrolysis of starch during permeation across {alpha}-amylase-immobilized porous hollow-fiber membranes

    Energy Technology Data Exchange (ETDEWEB)

    Miura, Suguru; Kubota, Noboru; Kawakita, Hidetaka; Saito, Kyoichi E-mail: marukyo@xtal.tf.chiba-u.ac.jp; Sugita, Kazuyuki; Watanabe, Kohei; Sugo, Takanobu

    2002-02-01

    Two kinds of supporting porous membranes, ethanolamine (EA) and phenol (Ph) fibers, for immobilization of {alpha}-amylase were prepared by radiation-induced graft polymerization of an epoxy-group-containing monomer, glycidyl methacrylate, onto a porous hollow-fiber membrane, and subsequent ring-opening with EA and Ph, respectively. An {alpha}-amylase solution was forced to permeate radially outward through the pores of the EA and Ph fibers. {alpha}-Amylase was captured at a density of 0.15 and 6.6 g/L of the membrane by the graft chain containing 2-hydroxyethylamino and phenyl groups, respectively. A permeation pressure of 0.10 MPa provided a space velocity of 780 and 1500 h{sup -1} for the {alpha}-amylase-immobilized EA and Ph fibers, respectively. Quantitative hydrolysis of starch during permeation of a 20 g/L starch solution in the buffer across the {alpha}-amylase-immobilized Ph fiber was attained up to a space velocity of about 2000 h{sup -1}; this was achieved because of negligible diffusional mass-transfer resistance of the starch to the {alpha}-amylase due to convective flow/ whereas an enzyme reaction-controlled system was observed for the {alpha}-amylase-immobilized EA fiber.

  20. High-throughput hydrolysis of starch during permeation across α-amylase-immobilized porous hollow-fiber membranes

    Science.gov (United States)

    Miura, Suguru; Kubota, Noboru; Kawakita, Hidetaka; Saito, Kyoichi; Sugita, Kazuyuki; Watanabe, Kohei; Sugo, Takanobu

    2002-02-01

    Two kinds of supporting porous membranes, ethanolamine (EA) and phenol (Ph) fibers, for immobilization of α-amylase were prepared by radiation-induced graft polymerization of an epoxy-group-containing monomer, glycidyl methacrylate, onto a porous hollow-fiber membrane, and subsequent ring-opening with EA and Ph, respectively. An α-amylase solution was forced to permeate radially outward through the pores of the EA and Ph fibers. α-Amylase was captured at a density of 0.15 and 6.6 g/L of the membrane by the graft chain containing 2-hydroxyethylamino and phenyl groups, respectively. A permeation pressure of 0.10 MPa provided a space velocity of 780 and 1500 h -1 for the α-amylase-immobilized EA and Ph fibers, respectively. Quantitative hydrolysis of starch during permeation of a 20 g/L starch solution in the buffer across the α-amylase-immobilized Ph fiber was attained up to a space velocity of about 2000 h -1; this was achieved because of negligible diffusional mass-transfer resistance of the starch to the α-amylase due to convective flow, whereas an enzyme reaction-controlled system was observed for the α-amylase-immobilized EA fiber.

  1. 85 km Long Reach PON System Using a Reflective SOA-EA Modulator and Distributed Raman Fiber Amplification

    DEFF Research Database (Denmark)

    Tafur Monroy, Idelfonso; Öhman, Filip; Yvind, Kresten

    2006-01-01

    We report on a bidirectional 85 km long reach PON system supported by distributed fiber Raman amplification with a record 7.5 Gb/s remote carrier modulated upstream signal by employing a reflective SOA-EA monolithically integrated circuit......We report on a bidirectional 85 km long reach PON system supported by distributed fiber Raman amplification with a record 7.5 Gb/s remote carrier modulated upstream signal by employing a reflective SOA-EA monolithically integrated circuit...

  2. Novel method for the design and assessment of direct contact membrane distillation modules

    OpenAIRE

    Field, RW; Wu, HY; Tay, WZ

    2016-01-01

    An equivalent effectiveness-number of heat transfer units (ε-NTUMD) method was developed for direct contact membrane distillation. Efficient performance rating and design sizing for individual DCMD modules can be rapidly made based upon limited experimental data. Using this method, the construction of a specific finite element model and their associated costs, involving both time and expenditure, are avoided. Instead the module performance or sizing requirements can be estimated efficiently u...

  3. Effects of fiber density and plasma modification of nanofibrous membranes on the adhesion and growth of HaCaT keratinocytes.

    Science.gov (United States)

    Bacakova, Marketa; Lopot, Frantisek; Hadraba, Daniel; Varga, Marian; Zaloudkova, Margit; Stranska, Denisa; Suchy, Tomas; Bacakova, Lucie

    2015-01-01

    It may be possible to regulate the cell colonization of biodegradable polymer nanofibrous membranes by plasma treatment and by the density of the fibers. To test this hypothesis, nanofibrous membranes of different fiber densities were treated by oxygen plasma with a range of plasma power and exposure times. Scanning electron microscopy and mechanical tests showed significant modification of nanofibers after plasma treatment. The intensity of the fiber modification increased with plasma power and exposure time. The exposure time seemed to have a stronger effect on modifying the fiber. The mechanical behavior of the membranes was influenced by the plasma treatment, the fiber density, and their dry or wet state. Plasma treatment increased the membrane stiffness; however, the membranes became more brittle. Wet membranes displayed significantly lower stiffness than dry membranes. X-ray photoelectron spectroscopy (XPS) analysis showed a slight increase in oxygen-containing groups on the membrane surface after plasma treatment. Plasma treatment enhanced the adhesion and growth of HaCaT keratinocytes on nanofibrous membranes. The cells adhered and grew preferentially on membranes of lower fiber densities, probably due to the larger area of void spaces between the fibers.

  4. An investigation of the influence of residual amplitude modulation in phase electro-optic modulator on the signal of fiber-optic gyroscope

    Science.gov (United States)

    Pogorelaya, D. A.; Smolovik, M. A.; Strigalev, V. E.; Aleynik, A. S.; Deyneka, I. G.

    2016-08-01

    The investigation is devoted to residual amplitude modulation (RAM) of phase electro-optic modulator, which guides are made in LiNbO3 crystal by Ti diffusion technology. An analysis is presented that shows influence of RAM on the signal of fiber-optic gyroscope. The RAM compensation method is offered.

  5. Optical signal monitoring in phase modulated optical fiber transmission systems

    Science.gov (United States)

    Zhao, Jian

    Optical performance monitoring (OPM) is one of the essential functions for future high speed optical networks. Among the parameters to be monitored, chromatic dispersion (CD) is especially important since it has a significant impact on overall system performance. In this thesis effective CD monitoring approaches for phase-shift keying (PSK) based optical transmission systems are investigated. A number of monitoring schemes based on radio frequency (RF) spectrum analysis and delay-tap sampling are proposed and their performance evaluated. A method for dispersion monitoring of differential phase-shift keying (DPSK) signals based on RF power detection is studied. The RF power spectrum is found to increase with the increase of CD and decrease with polarization mode dispersion (PMD). The spectral power density dependence on CD is studied theoretically and then verified through simulations and experiments. The monitoring sensitivity for nonreturn-to-zero differential phase-shift keying (NRZ-DPSK) and return-to-zero differential phase-shift keying (RZ-DPSK) based systems can reach 80ps/nm/dB and 34ps/nm/dB respectively. The scheme enables the monitoring of differential group delay (DGD) and CD simultaneously. The monitoring sensitivity of CD and DGD can reach 56.7ps/nm/dB and 3.1ps/dB using a bandpass filter. The effects of optical signal-to-noise ratio (OSNR), DGD, fiber nonlinearity and chirp on the monitoring results are investigated. Two RF pilot tones are employed for CD monitoring of DPSK signals. Specially selected pilot tone frequencies enable good monitoring sensitivity with minimum influence on the received signals. The dynamic range exceeding 35dB and monitoring sensitivity up to 9.5ps/nm/dB are achieved. Asynchronous sampling technique is employed for CD monitoring. A signed CD monitoring method for 10Gb/s NRZ-DPSK and RZ-DPSK systems using asynchronous delay-tap sampling technique is studied. The demodulated signals suffer asymmetric waveform distortion if

  6. Indole prevents Escherichia coli cell division by modulating membrane potential

    OpenAIRE

    Chimerel, Catalin; Field, Christopher M.; Piñero-Fernandez, Silvia; Keyser, Ulrich F.; Summers, David K.

    2012-01-01

    Indole is a bacterial signalling molecule that blocks E. coli cell division at concentrations of 3–5 mM. We have shown that indole is a proton ionophore and that this activity is key to the inhibition of division. By reducing the electrochemical potential across the cytoplasmic membrane of E. coli, indole deactivates MinCD oscillation and prevents formation of the FtsZ ring that is a prerequisite for division. This is the first example of a natural ionophore regulating a key biological proces...

  7. Identification and characterization of plasma membrane aquaporins isolated from fiber cells of Calotropis procera

    Institute of Scientific and Technical Information of China (English)

    Usman ASLAM; Asia KHATOON; Hafiza Masooma Naseer CHEEMA; Aftab BASHIR

    2013-01-01

    Calotropis procera,commonly known as "milkweed",possesses long seed trichomes for seed dispersal and has the ability to survive under harsh conditions such as drought and salinity.Aquaporins are water channel proteins expressed in all land plants,divided into five subfamilies plasma membrane intrinsic proteins (PIPs),tonoplast intrinsic proteins (TIPs),NOD26-1ike proteins (NIPs),small basic intrinsic proteins (SIPs),and the unfamiliar X intrinsic proteins (XlPs).PIPs constitute the largest group of water channel proteins that are involved in different developmental and regulatory mechanisms including water permeability,cell elongation,and stomata opening.Aquaporins are also involved in abiotic stress tolerance and cell expansion mechanisms,but their role in seed trichomes (fiber cells) has never been investigated.A large number of clones isolated from C.procera fiber cDNA library showed sequence homology to PIPs.Both expressed sequence tags (ESTs) and real-time polymerase chain reaction (PCR) studies revealed that the transcript abundance of this gene family in fiber cells of C.procera is greater than that of cotton.Full-length cDNAs of CpPIP1 and CpPIP2 were isolated from C.procera fiber cDNA library and used for constructing plant expression vectors under constitutive (2x35S) and trichome-specific (GhLTP3) promoters.Transgenic tobacco plants were developed via Agrobacterium-mediated transformation.The phenotypic characteristics of the plants were observed after confirming the integration of transgene in plants.It was observed that CpPIP2 expression cassette under 2x35S and GhLTP3 promoter enhanced the numbers of stem and leave trichomes.However,2x35S::CpPIP2 has a more amplified effect on trichome density and length than GhLTP3::CpPIP2 and other PIP constructs.These findings imply the role of C.procera PIP aquaporins in fiber cell elongation.The PIPs-derived cell expansion mechanism may be exploited through transgenic approaches for improvement of fiber staple

  8. Identification and characterization of plasma membrane aquaporins isolated from fiber cells of Calotropis procera.

    Science.gov (United States)

    Aslam, Usman; Khatoon, Asia; Cheema, Hafiza Masooma Naseer; Bashir, Aftab

    2013-07-01

    Calotropis procera, commonly known as "milkweed", possesses long seed trichomes for seed dispersal and has the ability to survive under harsh conditions such as drought and salinity. Aquaporins are water channel proteins expressed in all land plants, divided into five subfamilies plasma membrane intrinsic proteins (PIPs), tonoplast intrinsic proteins (TIPs), NOD26-like proteins (NIPs), small basic intrinsic proteins (SIPs), and the unfamiliar X intrinsic proteins (XIPs). PIPs constitute the largest group of water channel proteins that are involved in different developmental and regulatory mechanisms including water permeability, cell elongation, and stomata opening. Aquaporins are also involved in abiotic stress tolerance and cell expansion mechanisms, but their role in seed trichomes (fiber cells) has never been investigated. A large number of clones isolated from C. procera fiber cDNA library showed sequence homology to PIPs. Both expressed sequence tags (ESTs) and real-time polymerase chain reaction (PCR) studies revealed that the transcript abundance of this gene family in fiber cells of C. procera is greater than that of cotton. Full-length cDNAs of CpPIP1 and CpPIP2 were isolated from C. procera fiber cDNA library and used for constructing plant expression vectors under constitutive (2×35S) and trichome-specific (GhLTP3) promoters. Transgenic tobacco plants were developed via Agrobacterium-mediated transformation. The phenotypic characteristics of the plants were observed after confirming the integration of transgene in plants. It was observed that CpPIP2 expression cassette under 2×35S and GhLTP3 promoter enhanced the numbers of stem and leave trichomes. However, 2×35S::CpPIP2 has a more amplified effect on trichome density and length than GhLTP3::CpPIP2 and other PIP constructs. These findings imply the role of C. procera PIP aquaporins in fiber cell elongation. The PIPs-derived cell expansion mechanism may be exploited through transgenic approaches for

  9. Development of a High Performance PES Ultrafiltration Hollow Fiber Membrane for Oily Wastewater Treatment Using Response Surface Methodology

    Directory of Open Access Journals (Sweden)

    Noor Adila Aluwi Shakir

    2015-12-01

    Full Text Available This study attempts to optimize the spinning process used for fabricating hollow fiber membranes using the response surface methodology (RSM. The spinning factors considered for the experimental design are the dope extrusion rate (DER, air gap length (AGL, coagulation bath temperature (CBT, bore fluid ratio (BFR, and post-treatment time (PT whilst the response investigated is rejection. The optimal spinning conditions promising the high rejection performance of polyethersulfone (PES ultrafiltration hollow fiber membranes for oily wastewater treatment are at the dope extrusion rate of 2.13 cm3/min, air gap length of 0 cm, coagulation bath temperature of 30 °C, and bore fluid ratio (NMP/H2O of 0.01/99.99 wt %. This study will ultimately enable the membrane fabricators to produce high-performance membranes that contribute towards the availability of a more sustainable water supply system.

  10. Selective interfacial synthesis of metal-organic frameworks on a polybenzimidazole hollow fiber membrane for gas separation.

    Science.gov (United States)

    Biswal, Bishnu P; Bhaskar, Anand; Banerjee, Rahul; Kharul, Ulhas K

    2015-04-28

    Metal-organic frameworks (MOFs) have gained immense attention as new age materials due to their tuneable properties and diverse applicability. However, efforts on developing promising materials for membrane based gas separation, and control over the crystal growth positions on polymeric hollow fiber membranes still remain key challenges. In this investigation, a new, convenient and scalable room temperature interfacial method for growing MOFs (ZIF-8 and CuBTC) on either the outer or inner side of a polybenzimidazole based hollow fiber (PBI-BuI-HF) membrane surface has been achieved in a controlled manner. This was made possible by the appropriate selection of an immiscible solvent pair and the synthetic conditions. The growth of MOFs on the PBI-BuI-HF membrane by the interfacial method was continuous and showed an appreciable gas separation performance, conveying promise for their applicability.

  11. Measurement of CO2-laser-irradiation-induced refractive index modulation in single-mode fiber toward long-period fiber grating design and fabrication.

    Science.gov (United States)

    Li, Yanjun; Wei, Tao; Montoya, John A; Saini, Sandeep V; Lan, Xinwei; Tang, Xiling; Dong, Junhang; Xiao, Hai

    2008-10-10

    We report a new method to measure the CO(2)-laser-irradiation-induced refractive index modulation in the core of a single-mode optical fiber for the purpose of design and fabrication of long-period fiber gratings (LPFGs) without applying tension. Using an optical fiber Fabry-Perot interferometer, the laser-induced axial refractive index perturbation was measured. We found that the CO(2)-laser-irradiation-induced refractive index change in the fiber core had a negative value and that the magnitude was a sensitive function of the laser exposure time following almost a linear relation. Under the assumption of a Gaussian-shaped refractive index modulation profile and based on the first two terms of Fourier series approximation, the measured refractive index perturbations were used to simulate the LPFG transmission spectra. LPFGs with the same laser exposure parameters were fabricated without applying tension, and their spectra were compared with those obtained by simulations.

  12. A comparison of mass transfer coefficients between trickle-bed, hollow fiber membrane and stirred tank reactors.

    Science.gov (United States)

    Orgill, James J; Atiyeh, Hasan K; Devarapalli, Mamatha; Phillips, John R; Lewis, Randy S; Huhnke, Raymond L

    2013-04-01

    Trickle-bed reactor (TBR), hollow fiber membrane reactor (HFR) and stirred tank reactor (STR) can be used in fermentation of sparingly soluble gasses such as CO and H2 to produce biofuels and bio-based chemicals. Gas fermenting reactors must provide high mass transfer capabilities that match the kinetic requirements of the microorganisms used. The present study compared the volumetric mass transfer coefficient (K(tot)A/V(L)) of three reactor types; the TBR with 3 mm and 6 mm beads, five different modules of HFRs, and the STR. The analysis was performed using O2 as the gaseous mass transfer agent. The non-porous polydimethylsiloxane (PDMS) HFR provided the highest K(tot)A/V(L) (1062 h(-1)), followed by the TBR with 6mm beads (421 h(-1)), and then the STR (114 h(-1)). The mass transfer characteristics in each reactor were affected by agitation speed, and gas and liquid flow rates. Furthermore, issues regarding the comparison of mass transfer coefficients are discussed.

  13. Covalent Immobilization of Lipase on Poly ( acrylonitrile-co-maleic acid) Ultrafiltration Hollow Fiber Membrane

    Institute of Scientific and Technical Information of China (English)

    YE Peng; XU Zhi-kang; WU Jian; DENG Hong-tao; SETA Patrick

    2005-01-01

    Lipase from Candida rugosa was covalently immobilized on the surface of an ultrafiltration hollow fiber membrane fabricated from poly (acrylonitrile-co-maleic acid) (PANCMA) in which the carboxyl groups were activated with 1-ethyl-3-(dimethylaminopropyl) carbodiimide hydrochloride (EDC) and dicyclohexyl carbodiimide (DCC)/N-hydroxyl succinimide(NHS), respectively. The properties of the immobilized lipase were assayed and compared with those of the free enzyme. The maximum activities were observed in a relatively broader pH value range at high temperatures for the immobilized lipase compared to the free one. It was also found that the thermal and pH stabilities of lipase were improved upon immobilization and at 50 ℃ the thermal inactivation rate constant values are 2.1×10-2 for the free lipase, 3.2×10-3 for the immobilized lipase on the EDC-activated PANCMA membrane and 3.5×10-3 for the immobilized lipase on the DCC/NHS-activated PANCMA membrane, respectively.

  14. A graphite-coated carbon fiber epoxy composite bipolar plate for polymer electrolyte membrane fuel cell

    Science.gov (United States)

    Yu, Ha Na; Lim, Jun Woo; Suh, Jung Do; Lee, Dai Gil

    A PEMFC (polymer electrolyte membrane fuel cell or proton exchange membrane fuel cell) stack is composed of GDLs (gas diffusion layers), MEAs (membrane electrode assemblies), and bipolar plates. One of the important functions of bipolar plates is to collect and conduct the current from cell to cell, which requires low electrical bulk and interfacial resistances. For a carbon fiber epoxy composite bipolar plate, the interfacial resistance is usually much larger than the bulk resistance due to the resin-rich layer on the composite surface. In this study, a thin graphite layer is coated on the carbon/epoxy composite bipolar plate to decrease the interfacial contact resistance between the bipolar plate and the GDL. The total electrical resistance in the through-thickness direction of the bipolar plate is measured with respect to the thickness of the graphite coating layer, and the ratio of the bulk resistance to the interfacial contact resistance is estimated using the measured data. From the experiment, it is found that the graphite coating on the carbon/epoxy composite bipolar plate has 10% and 4% of the total electrical and interfacial contact resistances of the conventional carbon/epoxy composite bipolar plate, respectively, when the graphite coating thickness is 50 μm.

  15. Modulation of Erythrocyte Plasma Membrane Redox System Activity by Curcumin

    Directory of Open Access Journals (Sweden)

    Prabhakar Singh

    2016-01-01

    Full Text Available Plasma membrane redox system (PMRS is an electron transport chain system ubiquitously present throughout all cell types. It transfers electron from intracellular substrates to extracellular acceptors for regulation of redox status. Curcumin, isolated from Curcuma longa, has modulatory effects on cellular physiology due to its membrane interaction ability and antioxidant potential. The present study investigates the effect of curcumin on PMRS activity of erythrocytes isolated from Wistar rats in vitro and in vivo and validated through an in silico docking simulation study using Molegro Virtual Docker (MVD. Effects of curcumin were also evaluated on level of glutathione (GSH and the oxidant potential of plasma measured in terms of plasma ferric equivalent oxidative potentials (PFEOP. Results show that curcumin significantly (p<0.01 downregulated the PMRS activity in a dose-dependent manner. Molecular docking results suggest that curcumin interacts with amino acids at the active site cavity of cytochrome b5 reductase, a key constituent of PMRS. Curcumin also increased the GSH level in erythrocytes and plasma while simultaneously decreasing the oxidant potential (PFEOP of plasma. Altered PMRS activity and redox status are associated with the pathophysiology of several health complications including aging and diabetes; hence, the above finding may explain part of the role of curcumin in health beneficial effects.

  16. Sperm membrane modulation by Sapindus mukorossi during sperm maturation

    Institute of Scientific and Technical Information of China (English)

    ManishNivsarkar; NeetaShrivastava

    2002-01-01

    Aim:TO observe the alterations in the biochemical and biophysical changes in the sperm membrane during sperm maturation in male rats treated with the water extract of the fruit pericarp of S.mukorossi.Methods:Adult male Sprague-Dawley rats were gavaged the aqueous extract of the fruit pericarp of S.mukorossi at a dose of 50mg/kg/dfor45days.On day46,the sperm parameters were observed in idfferent sections of the epididymis and the sperm superoxide dismutase and the lipid peroxidation was edtermined and compared with the controls.The testis and epidiymis were routinely prepared for histological examination under the light microscope.Results:No significant differences in the sperm number and morphology were observed between the control and reated groups.However,a significant inhibition(P<0.05-0.01)of sperm motility in the caput,corpus and cauda regions of the epididymis was seen in the treated group.No significant histopathological changes were found in the testis and epididymis.Theimportant finding was that in the treated animals,the spermatozoa showed an abnormal distribution of the superoxide dismutase activity,being minimum in the caput and maximum in the corpus,which was just opposite to that of the controls.Conclusion:The study provides a unique observation where the plant extract alters the sperm membrane physiology without change the testicular and epididymal morphology.

  17. Optimization of the sinusoidal phase modulation technique in resonant fiber optic gyro

    Science.gov (United States)

    Wang, Linglan; Li, Hanzhao; Zhang, Jianjie; Ma, Huilian; Jin, Zhonghe

    2017-03-01

    The sinusoidal wave phase modulation and demodulation have been widely used in the signal processing system of the resonant fiber optic gyro (RFOG). An appropriate selection of the modulation frequency is of great importance, for the frequency value directly affects the slope of the demodulation curve at the resonance point which carries the gyro output information. A large demodulation slope is pursued in a high-performance RFOG. In this paper, an analytical expression of the demodulation slope is for the first time deduced in both transmission-type and reflection-type fiber ring resonators without any approximation. The relationship between the slope value and the modulation frequency at the resonance point is accurately calculated. The calculated best modulation frequency maximizing the demodulation slope at the resonance point is different from previous widely used optimal frequency given by the Lorentzian approximation method. More importantly, both theoretical and experimental results indicate that the achieved maximal demodulation slope from the proposed analytical expression method is double of that obtaining from the Lorentzian approximation method.

  18. Development of Polysulfone Hollow Fiber Porous Supports for High Flux Composite Membranes: Air Plasma and Piranha Etching

    OpenAIRE

    Ilya Borisov; Anna Ovcharova; Danila Bakhtin; Stepan Bazhenov; Alexey Volkov; Rustem Ibragimov; Rustem Gallyamov; Galina Bondarenko; Rais Mozhchil; Alexandr Bildyukevich; Vladimir Volkov

    2017-01-01

    For the development of high efficiency porous supports for composite membrane preparation, polysulfone (PSf) hollow fiber membranes (outer diameter 1.57 mm, inner diameter 1.12 mm) were modified by air plasma using the low temperature plasma treatment pilot plant which is easily scalable to industrial level and the Piranha etch (H2O2 + H2SO4). Chemical and plasma modification affected only surface layers and did not cause PSf chemical structure change. The modifications led to surface roughne...

  19. Removal of antibiotics in sponge membrane bioreactors treating hospital wastewater: Comparison between hollow fiber and flat sheet membrane systems.

    Science.gov (United States)

    Nguyen, Thanh-Tin; Bui, Xuan-Thanh; Luu, Vinh-Phuc; Nguyen, Phuoc-Dan; Guo, Wenshan; Ngo, Huu-Hao

    2017-09-01

    Hollow fiber (HF) and flat sheet (FS) Sponge MBRs were operated at 10-20 LMH flux treating hospital wastewater. Simultaneous nitrification denitrification (SND) occurred considerably with TN removal rate of 0.011-0.020mg TN mgVSS(-1)d(-1). Furthermore, there was a remarkable removal of antibiotics in both Sponge MBRs, namely Norfloxacin (93-99% (FS); 62-86% (HF)), Ofloxacin (73-93% (FS); 68-93% (HF)), Ciprofloxacin (76-93% (FS); 54-70% (HF)), Tetracycline (approximately 100% for both FS and HF) and Trimethoprim (60-97% (FS); 47-93% (HF). Whereas there was a quite high removal efficiency of Erythromycin in Sponge MBRs, with 67-78% (FS) and 22-48% (HF). Moreover, a slightly higher removal of antibiotics in FS than in HF achieved, with the removal rate being of 0.67-32.40 and 0.44-30.42µgmgVSS(-1)d(-1), respectively. In addition, a significant reduction of membrane fouling of 2-50 times was achieved in HF-Sponge MBR for the flux range. Copyright © 2017 Elsevier Ltd. All rights reserved.

  20. Mathematical model analysis on the enhancement of aeration efficiency using ladder-type flat membrane module forms in the Submerged Membrane Bio-reactor (SMBR)

    Institute of Scientific and Technical Information of China (English)

    LI Bo; YE MaoSheng; YANG FengLin; MA Hui

    2009-01-01

    The cross-flow shearing action produced from the inferior aeration in the Submerged Membrane Bio-reactor (SMBR) Is an effective way to further improve anti-fouling effects of membrane modules.Based on the widely-applied vertical structure of flat membrane modules, improvements are made that ladder-type flat membrane structure is designed with a certain inclined angle θ so that the cross-flow velocity of bubble near the membrane surface can be held, and the intensity and times of elastic colli-sion between bubbles and membrane surface can be increased. This can improve scouring action ofmembrane surface on aeration and reduce energy consumption of strong aeration in SMBR. By de-ducing and improving the mathematics model of collision between bubble and vertical flat put forward by Vries, the relatively suitable Incline angle θ under certain aeration place and in certain size rang ofbubble can be obtained with the computer iterative calculation technology. Finally, for many groups of ladder-type flat membrane in parallel placement in the practical application of SMBR, some sugges-tions are offered: the interval distance of membrane modules is 8--15 mm, and aeration should be op-erated at 5--7 mm among membrane modules, and the optimal design angle of trapeziform membrane is 1.7°--2.5°.

  1. Wet spinning of integrally skinned hollow fiber membranes by a modified dual-bath coagulation method using a triple orifice spinneret

    NARCIS (Netherlands)

    Li, S.-G.; Koops, G.H.; Mulder, M.H.V.; Boomgaard, van den A.; Smolders, C.A.

    1994-01-01

    Three main routes are known to prepare hollow fiber membranes; melt spinning, dry spinning and wet spinning (or dry/wet spinning). The latter is the most important technique for the preparation of industrial hollow fiber membranes. In this process the extruded polymer solution is immersed in a nonso

  2. Wet spinning of integrally skinned hollow fiber membranes by a modified dual-bath coagulation method using a triple orifice spinneret

    NARCIS (Netherlands)

    Li, S.G.; Li, S.-G.; Koops, G.H.; Mulder, M.H.V.; van den Boomgaard, Anthonie; Smolders, C.A.; Smolders, C.A.

    1994-01-01

    Three main routes are known to prepare hollow fiber membranes; melt spinning, dry spinning and wet spinning (or dry/wet spinning). The latter is the most important technique for the preparation of industrial hollow fiber membranes. In this process the extruded polymer solution is immersed in a nonso

  3. Review of the Strain Modulation Methods Used in Fiber Bragg Grating Sensors

    Directory of Open Access Journals (Sweden)

    Kuo Li

    2016-01-01

    Full Text Available Fiber Bragg grating (FBG is inherently sensitive to temperature and strain. By modulating FBG’s strain, various FBG sensors have been developed, such as sensors with enhanced or reduced temperature sensitivity, strain/displacement sensors, inclinometers, accelerometers, pressure meters, and magnetic field meters. This paper reviews the strain modulation methods used in these FBG sensors and categorizes them according to whether the strain of an FBG is changed evenly. Then, those even-strain-change methods are subcategorized into (1 attaching/embedding an FBG throughout to a base and (2 fixing the two ends of an FBG and (2.1 changing the distance between the two ends or (2.2 bending the FBG by applying a transverse force at the middle of the FBG. This review shows that the methods of “fixing the two ends” are prominent because of the advantages of large tunability and frequency modulation.

  4. Photonic aided bandpass sampling in coherent phase modulated radio-over-fiber links

    Science.gov (United States)

    Cao, Minghua; Li, Jianqiang; Dai, Jian; Dai, Yitang; Yin, Feifei; Zhou, Yue; Xu, Kun

    2016-06-01

    We have experimentally presented a digital coherent receiver employing photonic aided bandpass sampling technology for phase-modulated radio-over-fiber (RoF) links. An optical intensity modulator (IM) is utilized as the bandpass sampler which performs encoded on-off keyed pulse sequence on the optical local oscillator. Quaternary Phase Shift Keying (QPSK) modulated data signal with 20 MHz bandwidth at 5.2 GHz, 10.2 GHz and 15.2 GHz RF carrier frequency is experimentally demonstrated to be successfully detected by using balanced photodiodes (BPDs) with only 800 MHz analog bandwidth. It demonstrates that the required analog bandwidth of BPDs and ADCs can be dramatically reduced in a direct sampled coherent RoF communications system.

  5. Hyperpolarization of the membrane potential in cardiomyocyte tissue slices by the synchronization modulation electric field.

    Science.gov (United States)

    Dando, Robin; Fang, Zhihui; Chen, Wei

    2012-02-01

    Our previous studies have shown that a specially designed, so-called synchronization modulation electric field can entrain active transporter Na/K pumps in the cell membrane. This approach was previously developed in a study of single cells using a voltage clamp to monitor the pump currents. We are now expanding our study from isolated single cells to aggregated cells in a 3-dimensional cell matrix, through the use of a tissue slice from the rat heart. The slice is about 150 μm in thickness, meaning the slices contain many cell layers, resulting in a simplified 3-dimensional system. A fluorescent probe was used to identify the membrane potential and the ionic concentration gradients across the cell membrane. In spite of intrinsic cell-to-cell interactions and the difficulty in stimulating cell aggregation in the tissue slice, the oscillating electric field increased the intracellular fluorescent intensity, indicating elevation of the cell ionic concentration and hyperpolarization of the cell membrane. Blockage of these changes by ouabain confirmed that the results are directly related to Na/K pumps. These results along with the backward modulation indicate that the synchronization modulation electric field can influence the Na/K pumps in tissue cells of a 3-dimensional matrix and therefore hyperpolarize the cell membrane.

  6. Efficient synthesis of tension modulation in strings and membranes based on energy estimation.

    Science.gov (United States)

    Avanzini, Federico; Marogna, Riccardo; Bank, Balázs

    2012-01-01

    String and membrane vibrations cannot be considered as linear above a certain amplitude due to the variation in string or membrane tension. A relevant special case is when the tension is spatially constant and varies in time only in dependence of the overall string length or membrane surface. The most apparent perceptual effect of this tension modulation phenomenon is the exponential decay of pitch in time. Pitch glides due to tension modulation are an important timbral characteristic of several musical instruments, including the electric guitar and tom-tom drum, and many ethnic instruments. This paper presents a unified formulation to the tension modulation problem for one-dimensional (1-D) (string) and two-dimensional (2-D) (membrane) cases. In addition, it shows that the short-time average of the tension variation, which is responsible for pitch glides, is approximately proportional to the system energy. This proportionality allows the efficient physics-based sound synthesis of pitch glides. The proposed models require only slightly more computational resources than linear models as opposed to earlier tension-modulated models of higher complexity.

  7. Development and pilot testing of full-scale membrane distillation modules for deployment of waste heat

    NARCIS (Netherlands)

    Jansen, A.E.; Assink, J.W.; Hanemaaijer, J.H.; Medevoort, J. van; Sonsbeek, E. van

    2013-01-01

    Membrane distillation is an attractive technology for extracting fresh water from seawater. Newly developed modules have been used in pilot tests and bench scale tests to demonstrate the potential of producing excellent product water quality in a single step, little need for water pretreatment and a

  8. Modulation of Transmission Spectra of Anodized Alumina Membrane Distributed Bragg Reflector by Controlling Anodization Temperature

    Directory of Open Access Journals (Sweden)

    Zheng WenJun

    2009-01-01

    Full Text Available Abstract We have successfully prepared anodized alumina membrane distributed Bragg reflector (DBR using electrochemical anodization method. The transmission peak of this distributed Bragg reflector could be easily and effectively modulated to cover almost any wavelength range of the whole visible spectrum by adjusting anodization temperature.

  9. SCALE FACTOR DETERMINATION METHOD OF ELECTRO-OPTICAL MODULATOR IN FIBER-OPTIC GYROSCOPE

    Directory of Open Access Journals (Sweden)

    A. S. Aleynik

    2016-05-01

    Full Text Available Subject of Research. We propose a method for dynamic measurement of half-wave voltage of electro-optic modulator as part of a fiber optic gyroscope. Excluding the impact of the angular acceleration o​n measurement of the electro-optical coefficient is achieved through the use of homodyne demodulation method that allows a division of the Sagnac phase shift signal and an auxiliary signal for measuring the electro-optical coefficient in the frequency domain. Method. The method essence reduces to decomposition of step of digital serrodyne modulation in two parts with equal duration. The first part is used for quadrature modulation signals. The second part comprises samples of the auxiliary signal used to determine the value of the scale factor of the modulator. Modeling is done in standalone model, and as part of a general model of the gyroscope. The applicability of the proposed method is investigated as well as its qualitative and quantitative characteristics: absolute and relative accuracy of the electro-optic coefficient, the stability of the method to the effects of angular velocities and accelerations, method resistance to noise in actual devices. Main Results. The simulation has showed the ability to measure angular velocity changing under the influence of angular acceleration, acting on the device, and simultaneous measurement of electro-optical coefficient of the phase modulator without interference between these processes. Practical Relevance. Featured in the paper the ability to eliminate the influence of the angular acceleration on the measurement accuracy of the electro-optical coefficient of the phase modulator will allow implementing accurate measurement algorithms for fiber optic gyroscopes resistant to a significant acceleration in real devices.

  10. Iii-V Semiconductor Electroabsorption Waveguide Modulators for Long Wavelength Fiber Communication.

    Science.gov (United States)

    Lin, Shyh-Chung

    Long wavelength fiber communication has particular advantages in high speed, long haul communication system applications due to the intrinsic low chromatic dispersion and low attenuation of silica fibers at 1.3 mu m and 1.55 μm wavelengths. However, its implementation has been hampered by the lack of a high speed laser light modulator which has a small frequency variation (chirp) of its optical carrier. This thesis concerns III-V semiconductor electroabsorption waveguide modulators with the intention of improving their chirping characteristics and high speed performance. Analytical work performed in the course of this thesis has led to the following conclusions concerning the design and construction of electroabsorption waveguide modulators (EWM) for laser light modulation. (i) In order to minimize frequency chirping, semiconducting materials chosen for EWM applications should have a direct, fundamental bandgap somewhat greater than that of the incident laser photon energy. (ii) High speed EWMs require some compromises in terms of material parameters as well as dimensional constraints intended to minimize parasitic coupling impedances while providing basic, optimized, modulator functions such as low insertion loss, high modulation index, low driving voltage, and minimum frequency chirping. Experimental research on EWMs performed in the course of this thesis using liquid phase, epitaxially grown, quaternary alloy In_ xGa _{1-x}As_ yP _{1-y} and a laser wavelength of 1.3 μm includes: (i) Design, construction, and performance evaluation of a low capacitance ridge EWM. (ii) Design, construction, and performance evaluation of a buried channel EWM with large on-off ratio and the monolithic integration, in cascade, of such EWMs in order to perform the functions of a high speed phase comparator.

  11. Development of thin-film composite forward osmosis hollow fiber membranes using direct sulfonated polyphenylenesulfone (sPPSU) as membrane substrates.

    Science.gov (United States)

    Zhong, Peishan; Fu, Xiuzhu; Chung, Tai-Shung; Weber, Martin; Maletzko, Christian

    2013-07-02

    This study investigates a new approach to fabricate thin-film composite (TFC) hollow fiber membranes via interfacial polymerization for forward osmosis (FO) applications. Different degrees of sulfonation of polyphenylenesulfone (PPSU) were adopted as membrane substrates to investigate their impact on water flux. It has been established that the degree of sulfonation plays a role in both creating a macrovoid-free structure and inducing hydrophilicity to bring about higher water fluxes. The fabricated membranes exhibit extremely high water fluxes of 30.6 and 82.0 LMH against a pure water feed using 2.0 M NaCl as the draw solution tested under FO and pressure retarded osmosis (PRO) modes, respectively, while maintaining low salt reverse fluxes below 12.7 gMH. The structural parameter (S) displays remarkable decreases of up to 4.5 times as the membrane substrate is switched from a nonsulfonated to sulfonated one. In addition, the newly developed TFC-FO membranes containing 1.5 mol % sPPSU in the substrate achieves a water flux of 22 LMH in seawater desalination using a 3.5 wt % NaCl model solution and 2.0 M NaCl as the draw solution under the PRO mode. To the best of our knowledge, this value is the highest ever reported for seawater desalination using flat and hollow fiber FO membranes. The use of sulfonated materials in the FO process opens up a frontier for sustainable and efficient production of potable water.

  12. Modeling transcranial magnetic stimulation from the induced electric fields to the membrane potentials along tractography-based white matter fiber tracts

    Science.gov (United States)

    De Geeter, Nele; Dupré, Luc; Crevecoeur, Guillaume

    2016-04-01

    Objective. Transcranial magnetic stimulation (TMS) is a promising non-invasive tool for modulating the brain activity. Despite the widespread therapeutic and diagnostic use of TMS in neurology and psychiatry, its observed response remains hard to predict, limiting its further development and applications. Although the stimulation intensity is always maximum at the cortical surface near the coil, experiments reveal that TMS can affect deeper brain regions as well. Approach. The explanation of this spread might be found in the white matter fiber tracts, connecting cortical and subcortical structures. When applying an electric field on neurons, their membrane potential is altered. If this change is significant, more likely near the TMS coil, action potentials might be initiated and propagated along the fiber tracts towards deeper regions. In order to understand and apply TMS more effectively, it is important to capture and account for this interaction as accurately as possible. Therefore, we compute, next to the induced electric fields in the brain, the spatial distribution of the membrane potentials along the fiber tracts and its temporal dynamics. Main results. This paper introduces a computational TMS model in which electromagnetism and neurophysiology are combined. Realistic geometry and tissue anisotropy are included using magnetic resonance imaging and targeted white matter fiber tracts are traced using tractography based on diffusion tensor imaging. The position and orientation of the coil can directly be retrieved from the neuronavigation system. Incorporating these features warrants both patient- and case-specific results. Significance. The presented model gives insight in the activity propagation through the brain and can therefore explain the observed clinical responses to TMS and their inter- and/or intra-subject variability. We aspire to advance towards an accurate, flexible and personalized TMS model that helps to understand stimulation in the connected

  13. High RF power test of a lower hybrid module mock-up in carbon fiber composite

    Energy Technology Data Exchange (ETDEWEB)

    Goniche, M.; Bibet, P.; Brossaud, J.; Cano, V.; Froissard, P.; Kazarian, F.; Rey, G. [Association Euratom-CEA Cadarache, 13 - Saint-Paul-lez-Durance (France). Dept. de Recherches sur la Fusion Controlee; Maebara, S.; Kiyono, K.; Seki, M.; Suganuma, K.; Ikeda, Y.; Imai, T. [Japan Atomic Energy Research Inst., Tokyo (Japan). Dept. of Fusion Facility

    1999-02-01

    A mock-up module of a Lower Hybrid Current Drive antenna module of a Carbon Fiber Composite (CFC) was fabricated for the development of heat resistive front facing the plasma. This module is made from CFC plates and rods which are copper coated to reduce the RF losses. The withstand-voltage, the RF properties and outgassing rates for long pulses and high RF power were tested at the Lower Hybrid test bed facility of Cadarache. After the short pulse conditioning, long pulses with a power density ranging between 50 and 150 MW/m{sup 2} were performed with no breakdowns. During these tests, the module temperaturewas increasing from 100-200 deg. C to 400-500 deg. C. It was also checked that high power density, up to 150 MW/m{sup 2}, could be transmitted when the waveguides are filled with H{sub 2} at a pressure of 5 x 10{sup -2} Pa. No significant change in the reflection coefficient is measured after the long pulse operation. During a long pulse, the power reflection increases during the pulse typically from 0.8% to 1.3%. It is concluded that the outgassing rate of Cu-plated CFC is about 6 times larger than of Dispersion Strengthened Copper (DSC) module at the module temperature of 300 deg. C. No significant increase of the global outgassing of the CFC module was measured after hydrogen pre-filling. After the test, visual inspection revealed that peeling of the copper coating occurred at one end of the module only on a very small area (0.2 cm{sup 2}). It is assessed that a CFC module is an attractive candidate for the hardening of the tip of the LHCD antenna. (authors)

  14. Long-cavity all-fiber ring laser actively mode locked with an in-fiber bandpass acousto-optic modulator.

    Science.gov (United States)

    Cuadrado-Laborde, C; Bello-Jiménez, M; Díez, A; Cruz, J L; Andrés, M V

    2014-01-01

    We demonstrate low-frequency active mode locking of an erbium-doped all-fiber ring laser. As the mode locker, we used a new in-fiber bandpass acousto-optic modulator showing 74% modulation depth, 3.7 dB power insertion losses, 4.5 nm of optical bandwidth, and 20 dB of nonresonant light suppression. The laser generates 330 ps mode-locked pulses over a 10 ns pedestal, at a 1.538 MHz frequency, with 130 mW of pump power.

  15. Aerosol absorption measurement with a sinusoidal phase modulating fiber optic photo thermal interferometer

    Science.gov (United States)

    Li, Shuwang; Shao, Shiyong; Mei, Haiping; Rao, Ruizhong

    2016-10-01

    Aerosol light absorption plays an important role in the earth's atmosphere direct and semi-direct radiate forcing, simultaneously, it also has a huge influence on the visibility impairment and laser engineering application. Although various methods have been developed for measuring aerosol light absorption, huge challenge still remains in precision, accuracy and temporal resolution. The main reason is that, as a part of aerosol light extinction, aerosol light absorption always generates synchronously with aerosol light scattering, and unfortunately aerosol light scattering is much stronger in most cases. Here, a novel photo-thermal interferometry is proposed only for aerosol absorption measurement without disturbance from aerosol scattering. The photo-thermal interferometry consists of a sinusoidal phase-modulating single mode fiber-optic interferometer. The thermal dissipation, caused by aerosol energy from photo-thermal conversion when irritated by pump laser through interferometer, is detected. This approach is completely insensitive to aerosol scattering, and the single mode fiber-optic interferometer is compact, low-cost and insensitive to the polarization shading. The theory of this technique is illustrated, followed by the basic structure of the sinusoidal phase-modulating fiber-optic interferometer and demodulation algorithms. Qualitative and quantitative analysis results show that the new photo-thermal interference is a potential approach for aerosol absorption detection and environmental pollution detection.

  16. Fiber-based modulated optical reflectance configuration allowing for offset pump and probe beams

    Science.gov (United States)

    Fleming, A.; Folsom, C.; Jensen, C.; Ban, H.

    2016-12-01

    A new fiber-based modulated optical reflectance configuration is developed in this work. The technique maintains the fiber-based heating laser (pump) and detection laser (probe) in close proximity at a fixed separation distance in a ceramic ferrule. The pump beam periodically heats the sample inducing thermal waves into the sample. The probe beam measures the temperature response at a known distance from the pump beam over a range of heating modulation frequencies. The thermal diffusivity of the sample may be calculated from the phase response between the input heat flux and the temperature response of a sample having a reflective surface. The unique measurement configuration is ideal for in situ measurements and has many advantages for laboratory-based systems. The design and development of the system are reported along with theoretical justification for the experimental design. The thermal diffusivities of Ge and SiC are measured and found to be within 10% of reported literature values. The diffusivity for SiO2 is measured with a relative difference of approximately 100% from the literature value when the ferrule is in contact with the sample. An additional measurement was made on the SiO2 sample with the ferrule not in contact resulting in a difference of less than 2% from the literature value. The difference in the SiO2 measurement when the ferrule is in contact with the sample is likely due to a parallel heat transfer path through the dual-fiber ferrule assembly.

  17. Fouling of thin-channel and tubular membrane modules by dilute suspensions

    Energy Technology Data Exchange (ETDEWEB)

    Ilias, S.; Govind, R.

    1988-10-01

    In this paper, fouling of thin-channel and tubular ultrafiltration (UF) membrane modules by dilute suspensions have been studied theoretically. A hydrodynamic analysis of fluid-particle system is presented to describe the role of dilute suspensions in fouling such membrane modules. The present analysis assumes that for very dilute suspensions, only inertial effects are important for particulate fouling. Particle trajectory history and hence the fouling is computed from equations of motion for the particles, where the fluid-flow is given by the full solution of Navier-Stokes equation. To simulate the flux decline due to build up of foulant layer on the membrane walls, it is assumed that the deposition of particles on the membrane surface at discrete time interval is a steady state event and thus formulating the fouling problem as an infinite series of successive steady state events. Present simulation results indicate that inertial effects are important and under positive wall permeation flux conditions, particles are encouraged to migrate towards the membrane wall causing so-called membrane fouling by the particulates.

  18. Numerical Simulation and Analysis of CO2 Removal in a Polypropylene Hollow Fiber Membrane Contactor

    Directory of Open Access Journals (Sweden)

    Zhien Zhang

    2014-01-01

    Full Text Available This present study shows a comprehensive 2D numerical model for removal of CO2 in a polypropylene (PP hollow fiber membrane contactor (HFMC using the computational fluid dynamics (CFD method. Monoethanolamine (MEA solution was used as the liquid absorbent in a nonwetting mode. The simulation results represented that higher liquid velocity and concentration and lower gas velocity and concentration led to higher percent of CO2 removal. The most proper parameters for CO2 removal were less than 1 mol m−3 gas concentration and 0.2 m s−1 gas flow rate, and for MEA the values were above 8 mol m−3 concentration and approximately 1 m s−1 liquid velocity. Furthermore, the model was validated with the experiment results. Therefore, the modeling results provided references to the selection of absorbents and operation parameters in the experimental study and pilot-scale applications.

  19. Synthesis and characterization of polycaprolactone urethane hollow fiber membranes as small diameter vascular grafts.

    Science.gov (United States)

    Mercado-Pagán, Ángel E; Stahl, Alexander M; Ramseier, Michelle L; Behn, Anthony W; Yang, Yunzhi

    2016-07-01

    The design of bioresorbable synthetic small diameter (biodegradable polycaprolactone (PCL) urethane macromers to fabricate hollow fiber membranes (HFMs) as SDVG candidates, and characterized their mechanical properties, degradability, hemocompatibility, and endothelial development. The HFMs had smooth surfaces and porous internal structures. Their tensile stiffness ranged from 0.09 to 0.11N/mm and their maximum tensile force from 0.86 to 1.03N, with minimum failure strains of approximately 130%. Permeability varied from 1 to 14×10(-6)cm/s, burst pressures from 1158 to 1468mmHg, and compliance from 0.52 to 1.48%/100mmHg. The suture retention forces ranged from 0.55 to 0.81N. HFMs had slow degradation profiles, with 15 to 30% degradation after 8weeks. Human endothelial cells proliferated well on the HFMs, creating stable cell layer coverage. Hemocompatibility studies demonstrated low hemolysis (biodegradable elastomeric HFMs as SDVG candidates.

  20. Properties of fiber cell plasma membranes isolated from the cortex and nucleus of the porcine eye lens.

    Science.gov (United States)

    Mainali, Laxman; Raguz, Marija; O'Brien, William J; Subczynski, Witold K

    2012-04-01

    The organization and physical properties of the lipid bilayer portion of intact cortical and nuclear fiber cell plasma membranes isolated from the eye lenses of two-year-old pigs were studied using electron paramagnetic resonance (EPR) spin-labeling. Membrane fluidity, hydrophobicity, and the oxygen transport parameter (OTP) were assessed from the EPR spectra of precisely positioned spin labels. Intact cortical and nuclear membranes, which include membrane proteins, were found to contain three distinct lipid environments. These lipid environments were termed the bulk lipid domain, boundary lipid domain, and trapped lipid domain (lipids in protein aggregates). The amount of boundary and trapped lipids was greater in intact nuclear membranes than in cortical membranes. The properties of intact membranes were compared with the organization and properties of lens lipid membranes made of the total lipid extracts from the lens cortex or nucleus. In cortical lens lipid membranes, only one homogenous environment was detected, which was designated as a bulk lipid domain (phospholipid bilayer saturated with cholesterol). Lens lipid membranes prepared from the lens nucleus possessed two domains, assigned as a bulk lipid domain and a cholesterol bilayer domain (CBD). In intact nuclear membranes, it was difficult to discriminate the CBD, which was clearly detected in nuclear lens lipid membranes, because the OTP measured in the CBD is the same as in the domain formed by trapped lipids. The two domains unique to intact membranes-namely, the domain formed by boundary lipids and the domain formed by trapped lipids-were most likely formed due to the presence of membrane proteins. It is concluded that formation of rigid and practically impermeable domains is enhanced in the lens nucleus, indicating changes in membrane composition that may help to maintain low oxygen concentration in this lens region.

  1. 60-GHz Millimeter-wave Over Fiber with Directly Modulated Dual-mode Laser Diode

    Science.gov (United States)

    Tsai, Cheng-Ting; Lin, Chi-Hsiang; Lin, Chun-Ting; Chi, Yu-Chieh; Lin, Gong-Ru

    2016-06-01

    A directly modulated dual-mode laser diode (DMLD) with third-order intermodulation distortion (IMD3) suppression is proposed for a 60-GHz millimeter-wave over fiber (MMWoF) architecture, enabling new fiber-wireless communication access to cover 4-km single-mode-fiber (SMF) and 3-m wireless 16-QAM OFDM transmissions. By dual-mode injection-locking, the throughput degradation of the DMLD is mitigated with saturation effect to reduce its threshold, IMD3 power and relative intensity noise to 7.7 mA, ‑85 dBm and ‑110.4 dBc/Hz, respectively, providing huge spurious-free dynamic range of 85.8 dB/Hz2/3. This operation suppresses the noise floor of the DMLD carried QPSK-OFDM spectrum by 5 dB. The optical receiving power is optimized to restrict the power fading effect for improving the bit error rate to 1.9 × 10‑3 and the receiving power penalty to 1.1 dB. Such DMLD based hybrid architecture for 60-GHz MMW fiber-wireless access can directly cover the current optical and wireless networks for next-generation indoor and short-reach mobile communications.

  2. Cholesterol modulates the interaction of the islet amyloid polypeptide with membranes.

    Science.gov (United States)

    Caillon, Lucie; Duma, Luminita; Lequin, Olivier; Khemtemourian, Lucie

    2014-01-01

    The deposition of insoluble amyloid fibrils resulting from the aggregation of the human islet amyloid polypeptide (hIAPP) within the islet of Langerhans is a pathological feature of type 2 diabetes mellitus (T2DM). Increasing evidence indicates that biological membranes play a key role in amyloid aggregation, modulating among others the kinetics of amyloid formation, and being the target of toxic species generated during amyloid formation. In T2DM patients, elevated levels of cholesterol, an important determinant of the physical state of biological membranes, are observed in β-cells and are thought to directly impair β-cell function and insulin secretion. However, it is not known whether cholesterol enhances membrane-interaction or membrane-insertion of hIAPP. In this study, we investigated the effect of cholesterol incorporated in zwitterionic and anionic membranes. Our circular dichroism and liquid state NMR data reveal that 10-30% of cholesterol slightly affects the aggregational and conformational behaviour of hIAPP. Additional fluorescence results indicate that 10 and 20% of cholesterol slightly slow down the kinetics of oligomer and fibril formation while anionic lipids accelerate this kinetics. This behavior might be caused by differences in membrane insertion and therefore in membrane binding of hIAPP. The membrane binding affinity was evaluated using (1)H NMR experiments and our results show that the affinity of hIAPP for membranes containing cholesterol is significantly smaller than that for membranes containing anionic lipids. Furthermore, we found that hIAPP-induced membrane damage is synchronized to fibril formation in the absence and in the presence of cholesterol.

  3. On the subtle balance between competitive sorption and plasticization effects in asymmetric hollow fiber gas separation membranes

    NARCIS (Netherlands)

    Visser, Tymen; Koops, G.H.; Wessling, Matthias

    2005-01-01

    The paper describes the influence of a varying feed composition of CO2/CH4 and CO2/N2 mixtures on the gas separation performance of integrally skinned asymmetric PES/PI hollow fibers with an effective skin thickness of 0.27 ¿m. Normally, thin membrane structures (<3 ¿m) show accelerated plasticizati

  4. Weak polyelectrolyte multilayers as tunable separation layers for micro-pollutant removal by hollow fiber nanofiltration membranes

    NARCIS (Netherlands)

    Ilyas, Shazia; Mehran Abtahi, S.; Akkilic, Namik; Roesink, Hendrik Dirk Willem; de Vos, Wiebe Matthijs

    2017-01-01

    The presence of micro-pollutants in wastewater and in drinking water and its sources, is posing both environmental and health concerns. This work describes the development of weak polyelectrolyte multilayer (PEM) based hollow fiber nanofiltration (NF) membranes to remove micro-pollutants from

  5. The human periodontal membrane: focusing on the spatial interrelation between the epithelial layer of Malassez, fibers, and innervation

    DEFF Research Database (Denmark)

    Kjaer, Inger; Nolting, Dorrit

    2009-01-01

    OBJECTIVE: The purpose of the present study was to map the spatial interrelation of fibers, peripheral nerves, and epithelial layer of Malassez in human periodontal membrane in areas close to the root surfaces. MATERIAL AND METHODS: Four healthy permanent teeth extracted from four patients during...

  6. Synthesis and characterization of polycaprolactone urethane hollow fiber membranes as small diameter vascular grafts

    Energy Technology Data Exchange (ETDEWEB)

    Mercado-Pagán, Ángel E. [Department of Orthopedic Surgery, Stanford University, Stanford, CA (United States); Stahl, Alexander M. [Department of Orthopedic Surgery, Stanford University, Stanford, CA (United States); Department of Chemistry, Stanford University, Stanford, CA (United States); Ramseier, Michelle L. [Department of Orthopedic Surgery, Stanford University, Stanford, CA (United States); Department of Chemical Engineering, Stanford University, Stanford, CA (United States); Behn, Anthony W. [Department of Orthopedic Surgery, Stanford University, Stanford, CA (United States); Yang, Yunzhi, E-mail: ypyang@stanford.edu [Department of Orthopedic Surgery, Stanford University, Stanford, CA (United States); Department of Materials Science and Engineering, Stanford University, Stanford, CA (United States); Department of Bioengineering, Stanford University, Stanford, CA (United States)

    2016-07-01

    The design of bioresorbable synthetic small diameter (< 6 mm) vascular grafts (SDVGs) capable of sustaining long-term patency and endothelialization is a daunting challenge in vascular tissue engineering. Here, we synthesized a family of biocompatible and biodegradable polycaprolactone (PCL) urethane macromers to fabricate hollow fiber membranes (HFMs) as SDVG candidates, and characterized their mechanical properties, degradability, hemocompatibility, and endothelial development. The HFMs had smooth surfaces and porous internal structures. Their tensile stiffness ranged from 0.09 to 0.11 N/mm and their maximum tensile force from 0.86 to 1.03 N, with minimum failure strains of approximately 130%. Permeability varied from 1 to 14 × 10{sup −6} cm/s, burst pressures from 1158 to 1468 mm Hg, and compliance from 0.52 to 1.48%/100 mm Hg. The suture retention forces ranged from 0.55 to 0.81 N. HFMs had slow degradation profiles, with 15 to 30% degradation after 8 weeks. Human endothelial cells proliferated well on the HFMs, creating stable cell layer coverage. Hemocompatibility studies demonstrated low hemolysis (< 2%), platelet activation, and protein adsorption. There were no significant differences in the hemocompatibility of HFMs in the absence and presence of endothelial layers. These encouraging results suggest great promise of our newly developed materials and biodegradable elastomeric HFMs as SDVG candidates. - Highlights: • Polyester urethane hollow fiber membranes (HFMs) were fabricated and evaluated. • HFM properties varied according to composition. • HFM inner and outer surfaces were successfully seeded with cells. • HFMs showed excellent hemocompatibility in vitro. • HFM has the potential to be used for small diameter vascular grafts.

  7. Development and evaluation of elastomeric hollow fiber membranes as small diameter vascular graft substitutes

    Energy Technology Data Exchange (ETDEWEB)

    Mercado-Pagán, Ángel E.; Kang, Yunqing [Department of Orthopedic Surgery, Stanford University, Stanford, CA (United States); Findlay, Michael W. [Department of Plastic and Reconstructive Surgery, Stanford University, Stanford, CA (United States); University of Melbourne Department of Surgery, Royal Melbourne Hospital, Parkville, VIC (Australia); Yang, Yunzhi, E-mail: ypyang@stanford.edu [Department of Orthopedic Surgery, Stanford University, Stanford, CA (United States); Department of Materials Science and Engineering, Stanford University, Stanford, CA (United States)

    2015-04-01

    Engineering of small diameter (< 6 mm) vascular grafts (SDVGs) for clinical use remains a significant challenge. Here, elastomeric polyester urethane (PEU)-based hollow fiber membranes (HFMs) are presented as an SDVG candidate to target the limitations of current technologies and improve tissue engineering designs. HFMs are fabricated by a simple phase inversion method. HFM dimensions are tailored through adjustments to fabrication parameters. The walls of HFMs are highly porous. The HFMs are very elastic, with moduli ranging from 1–4 MPa, strengths from 1–5 MPa, and max strains from 300–500%. Permeability of the HFMs varies from 0.5–3.5 × 10{sup −6} cm/s, while burst pressure varies from 25 to 35 psi. The suture retention forces of HFMs are in the range of 0.8 to 1.2 N. These properties match those of blood vessels. A slow degradation profile is observed for all HFMs, with 71 to 78% of the original mass remaining after 8 weeks, providing a suitable profile for potential cellular incorporation and tissue replacement. Both human endothelial cells and human mesenchymal stem cells proliferate well in the presence of HFMs up to 7 days. These results demonstrate a promising customizable PEU HFMs for small diameter vascular repair and tissue engineering applications. - Highlights: • Hollow fiber membranes (HFMs) were fabricated and evaluated. • HFM properties could be tailored through adjustments to fabrication parameters. • Properties could match or exceed those of blood vessels. • HFM showed excellent compatibility in vitro. • HFMs have the potential to be used for small diameter vascular grafts.

  8. Autohydrogenotrophic denitrification of drinking water using a polyvinyl chloride hollow fiber membrane biofilm reactor.

    Science.gov (United States)

    Zhang, Yanhao; Zhong, Fohua; Xia, Siqing; Wang, Xuejiang; Li, Jixiang

    2009-10-15

    A hollow fiber membrane biofilm reactor (MBfR) using polyvinyl chloride (PVC) hollow fiber was evaluated in removing nitrate form contaminated drinking water. During a 279-day operation period, the denitrification rate increased gradually with the increase of influent nitrate loading. The denitrification rate reached a maximum value of 414.72 g N/m(3)d (1.50 g N/m(2)d) at an influent NO(3)(-)-N concentration of 10mg/L and a hydraulic residence time of 37.5 min, and the influent nitrate was completely reduced. At the same time, the effluent quality analysis showed the headspace hydrogen content (3.0%) was lower enough to preclude having an explosive air. Under the condition of the influent nitrate surface loading of 1.04 g N/m(2)d, over 90% removal efficiencies of the total nitrogen and nitrate were achieved at the hydrogen pressure above 0.04 MPa. The results of denaturing gel gradient electrophoresis (DGGE), 16S rDNA gene sequence analysis, and hierarchical cluster analysis showed that the microbial community structures in MBfR were of low diversity, simple and stable at mature stages; and the beta-Proteobacteria, including Rhodocyclus, Hydrogenophaga, and beta-Proteobacteria HTCC379, probably play an important role in autohydrogenotrophic denitrification.

  9. Single gain peak from modulation instability in As2Se3 chalcogenide glass photonic crystal fiber

    Science.gov (United States)

    Wang, Helin; Yang, Aijun

    2016-09-01

    With the As2Se3 photonic crystal fiber (PCF), the effect of pump power and wavelength on modulation instability (MI) gain is studied in detail. Due to high Raman scattering effect and high nonlinearity of As2Se3 PCF, ultra-broadband MI gain is obtained when appropriate pump power and wavelength is chosen, and the optimal MI gain bandwidth reaches 2812 nm. More importantly, competing between Raman scattering and four-wave mixing results in a single gain peak observed in the anti-Stokes region of As2Se3 PCF when pump power is higher than about 3000 W, while there is no gain spectrum in the fiber Stokes region. The phenomenon is found for the first time, and the obtained single gain peak mainly results from Raman scattering effect.

  10. Reconfigurable digital receiver for 8PSK subcarrier multiplexed and 16QAM single carrier phase‐modulated radio over fiber links

    DEFF Research Database (Denmark)

    Guerrero Gonzalez, Neil; Zibar, Darko; Yu, Xianbin

    2011-01-01

    A reconfigurable digital receiver based on the k‐means algorithm is proposed for phase‐modulated subcarrier multiplexed (SCM) and quadrature amplitude‐modulated single carrier, phase‐modulated radio‐over‐fiber links. We report successful demodulation after 40 km single mode fiber transmission...... with three 50 Mbaud 8PSK SCM signals and a 312.5 Mbaud 16QAM single carrier. © 2011 Wiley Periodicals, Inc. Microwave Opt Technol Lett 53:1015–1018, 2011; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.25905...

  11. Narciclasine, a plant growth modulator, activates Rho and stress fibers in glioblastoma cells.

    Science.gov (United States)

    Lefranc, Florence; Sauvage, Sébastien; Van Goietsenoven, Gwendoline; Mégalizzi, Véronique; Lamoral-Theys, Delphine; Debeir, Olivier; Spiegl-Kreinecker, Sabine; Berger, Walter; Mathieu, Véronique; Decaestecker, Christine; Kiss, Robert

    2009-07-01

    Cell motility and resistance to apoptosis characterize glioblastoma multiforme growth and malignancy. Narciclasine, a plant growth modulator, could represent a powerful new weapon targeting the Achilles' heel of glioblastoma multiforme and may offer the potential to better combat these devastating malignancies. The in vitro effects of narciclasine on cell proliferation, morphology, actin cytoskeleton organization, and the Rho/Rho kinase/LIM kinase/cofilin pathway and its antitumor activity in vivo have been determined in models of human glioblastoma multiforme. Narciclasine impairs glioblastoma multiforme growth by markedly decreasing mitotic rates without inducing apoptosis. The compound also modulates the Rho/Rho kinase/LIM kinase/cofilin signaling pathway, greatly increasing GTPase RhoA activity as well as inducing actin stress fiber formation in a RhoA-dependent manner. Lastly, the treatment of human glioblastoma multiforme orthotopic xenograft- bearing mice with nontoxic doses of narciclasine significantly increased their survival. Narciclasine antitumor effects were of the same magnitude as those of temozolomide, the drug associated with the highest therapeutic benefits in treating glioblastoma multiforme patients. Our results show for the first time that narciclasine, a plant growth modulator, activates Rho and stress fibers in glioblastoma multiforme cells and significantly increases the survival of human glioblastoma multiforme preclinical models. This statement is made despite the recognition that to date, irrespective of treatment, no single glioblastoma multiforme patient has been cured.

  12. RF-modulated pulsed fiber optic lidar transmitter for improved underwater imaging and communications

    Science.gov (United States)

    Kimpel, F.; Chen, Y.; Fouron, J.-L.; Akbulut, M.; Engin, D.; Gupta, S.

    2011-03-01

    We present results on the design, development and initial testing of a fiber-optic based RF-modulated lidar transmitter operating at 532nm, for underwater imaging application in littoral waters. The design implementation is based on using state-of-the-art high-speed FPGAs, thereby producing optical waveforms with arbitrary digital-RF-modulated pulse patterns with carrier frequencies >= 3GHz, with a repetition rate of 0.5-1MHz, and with average powers >=5W (at 532nm). Use of RF-modulated bursts above 500MHz, instead of single optical pulse lidar detection, reduces the effect of volumetric backscatter for underwater imaging application, leading to an improved signal-to-noise-ratio (SNR) and contrast, for a given range. Initial underwater target detection tests conducted at Patuxent River Naval Air Station, MD, in a large water-tank facility, validates the advantages of this hybrid-lidar-radar (HLR) approach for improved underwater imaging, over a wide range of turbidity levels and both white and black targets. The compact, robust and power-efficient fiber laser architecture lends very well to lidar sensor integration on unmanned-underwater-vehicle (UUV) platforms. HLR transmitters can also provide similar advantages in active-sensing situations dominated by continuous backscatter, e.g. underwater communications, imaging through smoke and fire environment, rotor-craft landing in degraded visual environment, and pointing-tracking of active-EO sensors through fog.

  13. Modulation, plasticity and pathophysiology of the parallel fiber-Purkinje cell synapse

    Directory of Open Access Journals (Sweden)

    Eriola Hoxha

    2016-11-01

    Full Text Available The parallel fiber-Purkinje cell synapse represents the point of maximal signal divergence in the cerebellar cortex with an estimated number of about 60 billion synaptic contacts in the rat and 100,000 billions in humans. At the same time, the Purkinje cell dendritic tree is a site of remarkable convergence of more than 100,000 parallel fiber synapses. Parallel fibers activity generates fast postsynaptic currents via AMPA receptors, and slower signals, mediated by mGlu1 receptors, resulting in Purkinje cell depolarization accompanied by sharp calcium elevation within dendritic regions. Long-term depression and long-term potentiation have been widely described for the parallel fiber-Purkinje cell synapse and have been proposed as mechanisms for motor learning. The mechanisms of induction for LTP and LTD involve different signaling mechanisms within the presynaptic terminal and/or at the postsynaptic site, promoting enduring modification in the neurotransmitter release and change in responsiveness to the neurotransmitter. The parallel fiber-Purkinje cell synapse is finely modulated by several neurotransmitters, including serotonin, noradrenaline, and acetylcholine. The ability of these neuromodulators to gate LTP and LTD at the parallel fiber-Purkinje cell synapse could, at least in part, explain their effect on cerebellar-dependent learning and memory paradigms. Overall, these findings have important implications for understanding the cerebellar involvement in a series of pathological conditions, ranging from ataxia to autism. For example, parallel fiber-Purkinje cell synapse dysfunctions have been identified in several murine models of spinocerebellar ataxia (SCA types 1, 3, 5 and 27. In some cases, the defect is specific for the AMPA receptor signaling (SCA27, while in others the mGlu1 pathway is affected (SCA1, 3, 5. Interestingly, the parallel fiber-Purkinje cell synapse has been shown to be hyper-functional in a mutant mouse model of autism

  14. Experimental demonstration of large capacity WSDM optical access network with multicore fibers and advanced modulation formats.

    Science.gov (United States)

    Li, Borui; Feng, Zhenhua; Tang, Ming; Xu, Zhilin; Fu, Songnian; Wu, Qiong; Deng, Lei; Tong, Weijun; Liu, Shuang; Shum, Perry Ping

    2015-05-01

    Towards the next generation optical access network supporting large capacity data transmission to enormous number of users covering a wider area, we proposed a hybrid wavelength-space division multiplexing (WSDM) optical access network architecture utilizing multicore fibers with advanced modulation formats. As a proof of concept, we experimentally demonstrated a WSDM optical access network with duplex transmission using our developed and fabricated multicore (7-core) fibers with 58.7km distance. As a cost-effective modulation scheme for access network, the optical OFDM-QPSK signal has been intensity modulated on the downstream transmission in the optical line terminal (OLT) and it was directly detected in the optical network unit (ONU) after MCF transmission. 10 wavelengths with 25GHz channel spacing from an optical comb generator are employed and each wavelength is loaded with 5Gb/s OFDM-QPSK signal. After amplification, power splitting, and fan-in multiplexer, 10-wavelength downstream signal was injected into six outer layer cores simultaneously and the aggregation downstream capacity reaches 300 Gb/s. -16 dBm sensitivity has been achieved for 3.8 × 10-3 bit error ratio (BER) with 7% Forward Error Correction (FEC) limit for all wavelengths in every core. Upstream signal from ONU side has also been generated and the bidirectional transmission in the same core causes negligible performance degradation to the downstream signal. As a universal platform for wired/wireless data access, our proposed architecture provides additional dimension for high speed mobile signal transmission and we hence demonstrated an upstream delivery of 20Gb/s per wavelength with QPSK modulation formats using the inner core of MCF emulating a mobile backhaul service. The IQ modulated data was coherently detected in the OLT side. -19 dBm sensitivity has been achieved under the FEC limit and more than 18 dB power budget is guaranteed.

  15. Correcting the wavefront aberration of membrane mirror based on liquid crystal spatial light modulator

    Science.gov (United States)

    Yang, Bin; Wei, Yin; Chen, Xinhua; Tang, Minxue

    2014-11-01

    Membrane mirror with flexible polymer film substrate is a new-concept ultra lightweight mirror for space applications. Compared with traditional mirrors, membrane mirror has the advantages of lightweight, folding and deployable, low cost and etc. Due to the surface shape of flexible membrane mirror is easy to deviate from the design surface shape, it will bring wavefront aberration to the optical system. In order to solve this problem, a method of membrane mirror wavefront aberration correction based on the liquid crystal spatial light modulator (LCSLM) will be studied in this paper. The wavefront aberration correction principle of LCSLM is described and the phase modulation property of a LCSLM is measured and analyzed firstly. Then the membrane mirror wavefront aberration correction system is designed and established according to the optical properties of a membrane mirror. The LCSLM and a Hartmann-Shack sensor are used as a wavefront corrector and a wavefront detector, respectively. The detected wavefront aberration is calculated and converted into voltage value on LCSLM for the mirror wavefront aberration correction by programming in Matlab. When in experiment, the wavefront aberration of a glass plane mirror with a diameter of 70 mm is measured and corrected for verifying the feasibility of the experiment system and the correctness of the program. The PV value and RMS value of distorted wavefront are reduced and near diffraction limited optical performance is achieved. On this basis, the wavefront aberration of the aperture center Φ25 mm in a membrane mirror with a diameter of 200 mm is corrected and the errors are analyzed. It provides a means of correcting the wavefront aberration of membrane mirror.

  16. Fabrication of Functionalized MOFs Incorporated Mixed Matrix Hollow Fiber Membrane for Gas Separation

    Directory of Open Access Journals (Sweden)

    Haitao Zhu

    2017-01-01

    Full Text Available The metal-organic framework (MOFs of MIL-53 was functionalized by aminosilane grafting and then incorporated into Ultem®1000 polymer matrix to fabricate mixed matrix hollow fiber membrane (MMHFM with high separation performance. SEM, XRD, and TGA were performed to characterize the functionalized MIL-53 and prepared MMHFM. The filler particles were embedded in membrane successfully and dispersed well in the polymer matrix. The incorporation of MOFs endowed MMHFM better thermal stability. Moreover, effects of solvent ratio in spinning dope, spinning condition, and testing temperature on gas separation performance of MMHFM were investigated. By optimizing dope composition, air gap distance, and bore fluid composition, MMHFM containing functionalized MIL-53 achieved excellent gas permeance and CO2/N2 selectivity. The CO2 permeance increased from 12.2 GPU for pure Ultem HFM to 30.9 GPU and the ideal CO2/N2 selectivity was enhanced from 25.4 to 34.7 simultaneously. Additionally, gas permeance increased but the selectivity decreased with the temperature increase, which followed the solution-diffusion based transport mechanism.

  17. Understanding the risk of scaling and fouling in hollow fiber forward osmosis membrane application

    KAUST Repository

    Majeed, Tahir

    2016-06-23

    Fouling studies of forward osmosis (FO) were mostly conducted based on fouling evaluation principals applied to pressure membrane processes such as reverse osmosis (RO)/nanofiltration (NF)/microfiltration (MF)/ultrafiltration (UF). For RO/NF/MF/UF processes, the single flux driving force (hydraulic pressure) remains constant, thus the fouling effect is easily evaluated by comparing flux data with the baseline. Whilst, the scenario of fouling effects for FO process is entirely different from RO/NF/MF/UF processes. Continuously changing driving force (osmotic pressure difference), the changes in concentration polarization associated with the varying draw solution/feed solution concentration and the fouling layer effects collectively influence the FO flux. Thus, usual comparison of the FO flux outcome with the baseline results can not exactly indicate the real affect of membrane fouling, rather presents a misleading cumulative effect. This study compares the existing FO fouling technique with an alternate fouling evaluation approach using two FO set-ups. Scaling and fouling risk for hollow fiber FO was separately investigated using synthetic water samples and model organic foulants as alginate, humic acid and bovine serum albumin. Results indicated that FO flux declines up to 5% and 49% in active layer-feed solution and active layer-draw solution orientations respectively.

  18. Non Dispersive Chemical Deacidification of Crude Palm Oil in Hollow Fiber Membrane Contactor

    Directory of Open Access Journals (Sweden)

    Mubiar Purwasasmita

    2015-09-01

    Full Text Available Performance of chemical deacidification of crude palm oil (CPO using aqueous NaOH solution in a polysulfone hollow fiber ultrafiltration membrane was investigated. The effects of operating temperature, NaOH concentration and flow rates on percentage of free fatty acids (FFA removal, oil loss, soap entrainment and overall mass transfer coefficient were evaluated. Overall mass transfer coefficients, soap content in oil and neutral oil loss all increased when the temperature was increased from 60 to 70°C due to an increase of the FFA distribution value. A minimum 0.25 N of NaOH or a NaOH to FFA molar ratio of about 7.62 was required to facilitate the expected extraction efficiency. The increased oil flowrate slightly enhanced the solute transport kinetics, while the aqueous phase flowrate did not significantly influence deacidification efficiency or mass transfer coefficient. About 97% of FFA removal was achieved within 4 hours. The maximum oil loss observed was 11% and the highest soap content in the oil without separation step was 3150 ppm. The values of the overall mass transfer coefficient varied from 2.97×10-7 to 7.71×10-7 m/s. These results show the potential of using the non dispersive membrane contacting process for chemical deacidification of CPO as well as other vegetable oils.

  19. Membrane cholesterol regulates lysosome-plasma membrane fusion events and modulates Trypanosoma cruzi invasion of host cells.

    Directory of Open Access Journals (Sweden)

    Bárbara Hissa

    Full Text Available BACKGROUND: Trypomastigotes of Trypanosoma cruzi are able to invade several types of non-phagocytic cells through a lysosomal dependent mechanism. It has been shown that, during invasion, parasites trigger host cell lysosome exocytosis, which initially occurs at the parasite-host contact site. Acid sphingomyelinase released from lysosomes then induces endocytosis and parasite internalization. Lysosomes continue to fuse with the newly formed parasitophorous vacuole until the parasite is completely enclosed by lysosomal membrane, a process indispensable for a stable infection. Previous work has shown that host membrane cholesterol is also important for the T. cruzi invasion process in both professional (macrophages and non-professional (epithelial phagocytic cells. However, the mechanism by which cholesterol-enriched microdomains participate in this process has remained unclear. METHODOLOGY/PRINCIPAL FINDING: In the present work we show that cardiomyocytes treated with MβCD, a drug able to sequester cholesterol from cell membranes, leads to a 50% reduction in invasion by T. cruzi trypomastigotes, as well as a decrease in the number of recently internalized parasites co-localizing with lysosomal markers. Cholesterol depletion from host membranes was accompanied by a decrease in the labeling of host membrane lipid rafts, as well as excessive lysosome exocytic events during the earlier stages of treatment. Precocious lysosomal exocytosis in MβCD treated cells led to a change in lysosomal distribution, with a reduction in the number of these organelles at the cell periphery, and probably compromises the intracellular pool of lysosomes necessary for T. cruzi invasion. CONCLUSION/SIGNIFICANCE: Based on these results, we propose that cholesterol depletion leads to unregulated exocytic events, reducing lysosome availability at the cell cortex and consequently compromise T. cruzi entry into host cells. The results also suggest that two different pools of

  20. Ouabain Modulates the Lipid Composition of Hippocampal Plasma Membranes from Rats with LPS-induced Neuroinflammation.

    Science.gov (United States)

    Garcia, Israel José Pereira; Kinoshita, Paula Fernanda; Scavone, Cristoforo; Mignaco, Julio Alberto; Barbosa, Leandro Augusto de Oliveira; Santos, Hérica de Lima

    2015-12-01

    The effects of ouabain (OUA) and lipopolysaccharide (LPS) in vivo on hippocampal membranes (RHM) of Wistar male rats aged 3 months were analyzed. After intraperitoneal (i.p.) injection of OUA only, LPS only, OUA plus LPS, or saline, the content of proteins, phospholipids, cholesterol and gangliosides from RHM was analyzed. The total protein and cholesterol contents of RHM were not significantly affected by OUA or LPS for the experimentally paired groups. In contrast, total phospholipids and gangliosides were strongly modulated by either OUA or LPS treatments. LPS reduced the total phospholipids (roughly 23 %) and increased the total gangliosides (approximately 40 %). OUA alone increased the total phospholipids (around 23 %) and also the total gangliosides (nearly 34 %). OUA pretreatment compensated the LPS-induced changes, preserving the total phospholipids and gangliosides around the same levels of the control. Thus, an acute treatment with OUA not only modulated the composition of hippocampal membranes from 3-month-old rats, but also was apparently able to counteract membrane alterations resulting from LPS-induced neuroinflammation. This study demonstrates for the first time that the OUA capacity modulates the lipid composition of hippocampal plasma membranes from rats with LPS-induced neuroinflammation.

  1. Pump-induced refractive index modulation and dispersions in Er3+-doped fibers

    DEFF Research Database (Denmark)

    Thirstrup, Carsten; Shi, Yuan

    1996-01-01

    A novel measurement system provides determination of pump induced phase shifts in erbium doped fibers with an accuracy of ~π/20. Using this system, a systematical analysis of the pump induced modulation of the refractive index and dispersions for a signal at 1550 nm and a pump at 980 nm is reported....... The analysis contains measurements of pump induced refractive index changes as function of wavelength, pump power, and doping concentration. A model taking account of the contribution to the refractive index changes from optical transitions between 4 I15/2 states and 4I13/2 states in Er3+ yields good agreement...

  2. Sinusoidal phase-modulating fiber-optic interferometer fringe with a feedback control system.

    Science.gov (United States)

    Lv, Changrong; Duan, Fajie; Bo, En; Duan, Xiaojie; Feng, Fan; Fu, Xiao

    2014-09-20

    A displacement measurement system using a fiber-optic interferometer fringe projector with a feedback control system is presented and demonstrated. The system utilizes the integrating bucket method to detect the desired phase or the displacement and Fresnel reflection signal to realize measurement of the disturbance and feed it back to the modulated signal of the laser at the same time. The continuous signal truly reflects the error information, as the output light and reflected light share the same optical path. Practical experiments validate the feasibility of this method.

  3. A Q-switched, mode-locked fiber laser employing subharmonic cavity modulation.

    Science.gov (United States)

    Chang, You Min; Lee, Junsu; Lee, Ju Han

    2011-12-19

    We present a new and simple approach for the generation of Q-switched, mode-locked pulses from a laser cavity. The approach is based on cavity loss modulation that employs a subharmonic frequency of the fundamental intermode frequency spacing. A range of experiments have been carried out using an erbium-doped fiber-based ring cavity laser in order to verify that this simple approach can readily produce high quality Q-switched, mode-locked pulses. An active tuning of the Q-switched envelope repetition rate is also shown to be easily achievable by adjusting the order of the applied subharmonic frequency.

  4. PEMURNIAN MINYAK KELAPA SAWIT MENGGUNAKAN MEMBRAN SERAT BERONGGA (Purifi cation of Palm Oil by Using Hollow Fiber Membrane

    Directory of Open Access Journals (Sweden)

    Nasrul Arahman

    2013-06-01

    1307. Hasil karakterisasi dengan SEM menunjukkan bahwa membran yang terbuat dari bahan PES/NMP/PVP, dan PES/NMP/Tetronic 1307 mempunyai struktur macrovoid yang lebih banyak dan ukuran yang lebih besar dibandingkan dengan membran yang terbuat dari bahan PES/NMP. Sifat hidrofilisitas membran campuran juga menjadi lebih baik jika dibandingkan dengan membran tunggal PES/NMP. Fluks minyak kelapa sawit terbesar diperoleh 0,27 L/m2.hr.atm pada kondisi tekanan operasi 2,0 kg/cm2 untuk membran hollow fi ber dari bahan PES/NMP/PVP. Kata kunci: Membran serat berongga, polietersulfon, minyak kelapa sawit

  5. Dispersion-modulation by high material loss in microstructured polymer optical fibers

    DEFF Research Database (Denmark)

    Frosz, Michael Henoch

    2009-01-01

    -induced dispersion significantly modifies the wavelengths for which there is phase-match. Depending on the pump wavelength, the waveguide disper­sion, and the loss peaks, it is possible for the output spectrum to either be unaffected by the loss-induced dispersion modulation, or to show an in......The influence of strong loss peaks on the dispersion (through the Kramers-Kronig relations) of a nonlinear waveguide is investigated theore­ti­cally. It is found specifically for degenerate four-wave mixing in a poly(methyl methacrylate) microstructured polymer optical fiber that the loss......­crea­se in the efficiency of nonlinear spectral broadening, compared to the ex­pected efficiency when ignoring the loss-induced dispersion modulation....

  6. [Effect of plasma membrane ion permeability modulators on respiration and heat output of wheat roots].

    Science.gov (United States)

    Alekseeva, V A; Gordon, L Kh; Loseva, N L; Rakhimova, G G; Tsentsevitskiĭ, A N

    2006-01-01

    A study was made of changes in the rates of respiration, heat production, and membrane characteristics in cells of excised roots of wheat seedlings under the modulation of plasma membrane ion permeability by two membrane active compounds: valinomycin (20 microM (V50)) and chlorpromazine (50 microM (CP50) and 100 microM (CP100)). Both compounds increased the loss of potassium ions, which correlated with the lowering of membrane potential, rate of respiration, and heat production after a 2 h exposure. The differences in alteration of these parameters were due to specific action of either compound on the membrane and to the extent of ion homeostasis disturbance. V20 had a weak effect on the studied parameters. V50 caused an increase of the rate of respiration and heat production, which enhanced following a prolonged action (5 h) and were associated with ion homeostatis restoration. The extent of alteration of membrane characteristics (an increase of potassium loss by roots, and lowering of cell membrane potential) as well as energy expense under the action of CP50 during the first period were more pronounced than in the presence of V50. During a prolonged action of CP50, the increase of respiration intensity and heat production correlated with partial recovery of ion homeostatis in cells. Essential lowering of membrane potential and substantial loss of potassium by cells, starting from the early stages of their response reaction, were followed by inhibition of respiration rate and heat production. Alterations of the structure and functional characteristics of excised root cells indicate the intensification of the membrane-tropic effect of a prolonged action of CP100, and the lack of cell energy resources.

  7. Preparation of PVA/PEI ultra-fine fibers and their composite membrane with PLA by electrospinning.

    Science.gov (United States)

    Dong, Cunhai; Yuan, Xiaoyan; He, Mingyu; Yao, Kangde

    2006-01-01

    Ultra-fine fibers of poly(vinyl alcohol)/polyethylenimine (PVA/PEI) were prepared by electrospinning of their blend solutions in water. Effects of PVA/PEI mass ratio and the polymer concentration on the fiber morphology were discussed by analysis of scanning electron micrographs. Results showed that uniform ultra-fine fibers could be obtained from an 8% PVA/PEI solution with 75:25 mass ratio. It was supposed that the introduction of PVA could promote electrospinning of PEI by weakening the intermolecular interaction and increasing solution viscosity. A composite membrane of PVA/PEI with poly(D,L-lactide) (PLA) was produced by co-electrospinning simultaneously from the aqueous 8% PVA/PEI (75:25) solution and a 20% PLA solution in N,N-dimethylformamide in two separated syringes. Fourier transform infrared spectroscopy, X-ray diffraction and X-ray photoelectron spectroscopy verified the existence of PVA/PEI and PLA in the fibrous membrane. We attempted to incorporate PEI with PLA as ultra-fine fibers to diminish the acidic inflammation caused by biodegradation of PLA. The fibrous composite membrane of PVA/PEI-PLA could provide better biocompatibility and would be used as drug-delivery carriers or tissue-engineering scaffolds.

  8. Gene expression changes of single skeletal muscle fibers in response to modulation of the mitochondrial calcium uniporter (MCU

    Directory of Open Access Journals (Sweden)

    Francesco Chemello

    2015-09-01

    Full Text Available The mitochondrial calcium uniporter (MCU gene codifies for the inner mitochondrial membrane (IMM channel responsible for mitochondrial Ca2+ uptake. Cytosolic Ca2+ transients are involved in sarcomere contraction through cycles of release and storage in the sarcoplasmic reticulum. In addition cytosolic Ca2+ regulates various signaling cascades that eventually lead to gene expression reprogramming. Mitochondria are strategically placed in close contact with the ER/SR, thus cytosolic Ca2+ transients elicit large increases in the [Ca2+] of the mitochondrial matrix ([Ca2+]mt. Mitochondrial Ca2+ uptake regulates energy production and cell survival. In addition, we recently showed that MCU-dependent mitochondrial Ca2+ uptake controls skeletal muscle trophism. In the same report, we dissected the effects of MCU-dependent mitochondrial Ca2+ uptake on gene expression through microarray gene expression analysis upon modulation of MCU expression by in vivo AAV infection. Analyses were performed on single skeletal muscle fibers at two time points (7 and 14 days post-AAV injection. Raw and normalized data are available on the GEO database (http://www.ncbi.nlm.nih.gov/geo/ (GSE60931.

  9. Gene expression changes of single skeletal muscle fibers in response to modulation of the mitochondrial calcium uniporter (MCU).

    Science.gov (United States)

    Chemello, Francesco; Mammucari, Cristina; Gherardi, Gaia; Rizzuto, Rosario; Lanfranchi, Gerolamo; Cagnin, Stefano

    2015-09-01

    The mitochondrial calcium uniporter (MCU) gene codifies for the inner mitochondrial membrane (IMM) channel responsible for mitochondrial Ca(2 +) uptake. Cytosolic Ca(2 +) transients are involved in sarcomere contraction through cycles of release and storage in the sarcoplasmic reticulum. In addition cytosolic Ca(2 +) regulates various signaling cascades that eventually lead to gene expression reprogramming. Mitochondria are strategically placed in close contact with the ER/SR, thus cytosolic Ca(2 +) transients elicit large increases in the [Ca(2 +)] of the mitochondrial matrix ([Ca(2 +)]mt). Mitochondrial Ca(2 +) uptake regulates energy production and cell survival. In addition, we recently showed that MCU-dependent mitochondrial Ca(2 +) uptake controls skeletal muscle trophism. In the same report, we dissected the effects of MCU-dependent mitochondrial Ca(2 +) uptake on gene expression through microarray gene expression analysis upon modulation of MCU expression by in vivo AAV infection. Analyses were performed on single skeletal muscle fibers at two time points (7 and 14 days post-AAV injection). Raw and normalized data are available on the GEO database (http://www.ncbi.nlm.nih.gov/geo/) (GSE60931).

  10. Mode-locking and Q-switching in multi-wavelength fiber ring laser using low frequency phase modulation.

    Science.gov (United States)

    Jun, Chang Su; Kim, Byoung Yoon

    2011-03-28

    We describe experimental investigation of pulsed output from a multi-wavelength fiber ring laser incorporating low frequency phase modulation with large modulation amplitude. The Erbium-doped fiber (EDF) ring laser generated more than 8 wavelength channels with the help of a phase modulator operating at 26.2 kHz and a periodic intra-cavity filter. For most cases, the laser output is pulsed in the form of mode-locking at 5.62 MHz and/or Q-switching at harmonic and sub-harmonic of the phase modulation frequency. Chaotic pulse output is also observed. The behavior of the output pulses are described as functions of pump power and phase modulation amplitude. The relative intensity noise (RIN) value of a single wavelength channel is measured to be under -100 dB/Hz (-140 dB/Hz beyond 1.5 GHz).

  11. Preform rod feeding module of the optical fiber drawing tower and its algorithm design based on STM32

    Science.gov (United States)

    Zhang, Tao; Fan, Zhaocheng; Liu, Guanyu; Geng, Tao; Li, Xin

    2012-10-01

    Preform rod feeding module is pre-stage module in the system of Optical Fiber Drawing Tower, its stability directly affects the wire diameter precision of the fiber. For meeting the demand of scientific research to special optical fiber, we design a new kind of preform rod feeding system, using STM32 as development platform, high-performance actuating motor as executive device and high precision grating ruler as measurement device. In order to improve the stability of the system, we adopt the algorithm design of PID closed-loop control. Finally, real-time monitoring and fast response control of preform rod operation state is realized. The results show that the system runs steadily, and can meet production requirement of special optical fiber.

  12. Pressure retarded osmosis dual-layer hollow fiber membranes developed by co-casting method and ammonium persulfate (APS) treatment

    KAUST Repository

    Fu, Fengjiang

    2014-11-01

    Delamination and low water permeability are two issues limiting the applications of dual-layer hollow fiber membranes in the pressure retarded osmosis (PRO) process. In this work, we first developed a universal co-casting method that is able to co-cast highly viscous dope solutions to form homogeneous dual-layer flat sheet membranes. By employing this method prior to the tedious dual-layer hollow fiber spinning process, both time and material consumptions are significantly saved. The addition of polyvinylpyrrolidone (PVP) is found to eliminate delamination at the sacrifice of water flux. A new post-treatment method that involves flowing ammonium persulfate (APS) solution and DI water counter-currently is potentially to remove the PVP molecules entrapped in the substrate while keeps the integrity of the interface. As the APS concentration increases, the water flux in the PRO process is increased while the salt leakage is slightly decreased. With the optimized APS concentration of 5wt%, the post-treated membrane shows a maximum power density of 5.10W/m2 at a hydraulic pressure of 15.0bar when 1M NaCl and 10mM NaCl were used as the draw and feed solutions, respectively. To the extent of our knowledge, this is the best phase inversion dual-layer hollow fiber membrane with an outer selective layer for osmotic power generation. © 2014 Elsevier B.V.

  13. Cell cycle regulation of dynein association with membranes modulates microtubule-based organelle transport.

    Science.gov (United States)

    Niclas, J; Allan, V J; Vale, R D

    1996-05-01

    Cytoplasmic dynein is a minus end-directed microtubule motor that performs distinct functions in interphase and mitosis. In interphase, dynein transports organelles along microtubules, whereas in metaphase this motor has been implicated in mitotic spindle formation and orientation as well as chromosome segregation. The manner in which dynein activity is regulated during the cell cycle, however, has not been resolved. In this study, we have examined the mechanism by which organelle transport is controlled by the cell cycle in extracts of Xenopus laevis eggs. Here, we show that photocleavage of the dynein heavy chain dramatically inhibits minus end-directed organelle transport and that purified dynein restores this motility, indicating that dynein is the predominant minus end-directed membrane motor in Xenopus egg extracts. By measuring the amount of dynein associated with isolated membranes, we find that cytoplasmic dynein and its activator dynactin detach from the membrane surface in metaphase extracts. The sevenfold decrease in membrane-associated dynein correlated well with the eightfold reduction in minus end-directed membrane transport observed in metaphase versus interphase extracts. Although dynein heavy or intermediate chain phosphorylation did not change in a cell cycle-dependent manner, the dynein light intermediate chain incorporated approximately 12-fold more radiolabeled phosphate in metaphase than in interphase extracts. These studies suggest that cell cycle-dependent phosphorylation of cytoplasmic dynein may regulate organelle transport by modulating the association of this motor with membranes.

  14. Therapeutic design of peptide modulators of protein-protein interactions in membranes.

    Science.gov (United States)

    Stone, Tracy A; Deber, Charles M

    2017-04-01

    Membrane proteins play the central roles in a variety of cellular processes, ranging from nutrient uptake and signalling, to cell-cell communication. Their biological functions are directly related to how they fold and assemble; defects often lead to disease. Protein-protein interactions (PPIs) within the membrane are therefore of great interest as therapeutic targets. Here we review the progress in the application of membrane-insertable peptides for the disruption or stabilization of membrane-based PPIs. We describe the design and preparation of transmembrane peptide mimics; and of several categories of peptidomimetics used for study, including d-enantiomers, non-natural amino acids, peptoids, and β-peptides. Further aspects of the review describe modifications to membrane-insertable peptides, including lipidation and cyclization via hydrocarbon stapling. These approaches provide a pathway toward the development of metabolically stable, non-toxic, and efficacious peptide modulators of membrane-based PPIs. This article is part of a Special Issue entitled: Lipid order/lipid defects and lipid-control of protein activity edited by Dirk Schneider.

  15. Modulating membrane composition alters free fatty acid tolerance in Escherichia coli.

    Directory of Open Access Journals (Sweden)

    Rebecca M Lennen

    Full Text Available Microbial synthesis of free fatty acids (FFA is a promising strategy for converting renewable sugars to advanced biofuels and oleochemicals. Unfortunately, FFA production negatively impacts membrane integrity and cell viability in Escherichia coli, the dominant host in which FFA production has been studied. These negative effects provide a selective pressure against FFA production that could lead to genetic instability at industrial scale. In prior work, an engineered E. coli strain harboring an expression plasmid for the Umbellularia californica acyl-acyl carrier protein (ACP thioesterase was shown to have highly elevated levels of unsaturated fatty acids in the cell membrane. The change in membrane content was hypothesized to be one underlying cause of the negative physiological effects associated with FFA production. In this work, a connection between the regulator of unsaturated fatty acid biosynthesis in E. coli, FabR, thioesterase expression, and unsaturated membrane content was established. A strategy for restoring normal membrane saturation levels and increasing tolerance towards endogenous production of FFAs was implemented by modulating acyl-ACP pools with a second thioesterase (from Geobacillus sp. Y412MC10 that primarily targets medium chain length, unsaturated acyl-ACPs. The strategy succeeded in restoring membrane content and improving viability in FFA producing E. coli while maintaining FFA titers. However, the restored fitness did not increase FFA productivity, indicating the existence of additional metabolic or regulatory barriers.

  16. Glycine and beta-branched residues support and modulate peptide helicity in membrane environments.

    Science.gov (United States)

    Li, S C; Deber, C M

    1992-10-26

    Transmembrane (TM) segments of integral membrane proteins are putatively alpha-helical in conformation once inserted into the membrane, yet consist of primary sequences rich in residues known in soluble proteins as helix-breakers (Gly) and beta-sheet promoters (Ile, Val, Thr). To examine the specific 2 degrees structure propensities of such residues in membrane environments, we have designed and synthesized a series of 20-residue peptides with 'guest' hydrophobic segments--expected to provide three turns of incipient alpha-helix content--embedded in 'host' hydrophilic (Lys-Ser) matrices. Circular dichroism (CD) spectra of the model peptides in water showed that significant helical content was observed only for peptides with high Ala content; others behaved as 'random coils'. However, in the membrane-mimetic environment of sodium dodecylsulfate (SDS) micelles, it was found that Gly can be accommodated as readily as Ala, and Ile or Val as readily as Leu, in hydrophobic alpha-helices. Further subtleties of structural preferences could be observed in electrically-neutral lyso-phosphatidylcholine (LPC) micelles, where helical propensity decreased in the order Ala-Leu-rich > Gly-Leu-rich > Gly-Ile(Val)-rich hydrophobic segments. The results conjure a role of environment-dependent helix-modulation for Gly, Ile, and Val residues--and suggest that these residues may provide, in part, the structural basis for conformational transitions within or adjacent to membrane domains, such as those accompanying membrane insertion and/or required for transport or signalling functions.

  17. Modifying glass fiber surface with grafting acrylamide by UV-grafting copolymerization for preparation of glass fiber reinforced PVDF composite membrane.

    Science.gov (United States)

    Luo, Nan; Zhong, Hui; Yang, Min; Yuan, Xing; Fan, Yaobo

    2016-01-01

    Experimental design and response surface methodology (RSM) were used to optimize the modification of conditions for glass surface grafting with acrylamide (AM) monomer for preparation of a glass fiber reinforced poly(vinylidene fluoride) (PVDF) composite membrane (GFRP-CM). The factors considered for experimental design were the UV (ultraviolet)-irradiation time, the concentrations of the initiator and solvent, and the kinds and concentrations of the silane coupling agent. The optimum operating conditions determined were UV-irradiation time of 25 min, an initiator concentration of 0-0.25 wt.%, solvent of N-Dimethylacetamide (DMAC), and silane coupling agent KH570 with a concentration of 7 wt.%. The obtained optimal parameters were located in the valid region and the experimental confirmation tests conducted showed good accordance between predicted and experimental values. Under these optimal conditions, the water absorption of the grafted modified glass fiber was improved from 13.6% to 23%; the tensile strength was enhanced and the peeling strength of the glass fiber reinforced PVDF composite membrane was improved by 23.7% and 32.6% with an AM concentration at 1 wt.% and 2 wt.%. The surface composition and microstructure of AM grafted glass fiber were studied via several techniques including Field Emission Scanning Electron Microscopy (FESEM), Fourier transform infrared spectroscopy-attenuated total reflectance (FTIR-ATR) and energy dispersive X-ray spectroscopy (EDX). The analysis of the EDX and FTIR-ATR results confirmed that the AM was grafted to the glass fiber successfully by detecting and proving the existence of nitrogen atoms in the GFRP-CM.

  18. Membrane Distribution of the Pseudomonas Quinolone Signal Modulates Outer Membrane Vesicle Production in Pseudomonas aeruginosa.

    Science.gov (United States)

    Florez, Catalina; Raab, Julie E; Cooke, Adam C; Schertzer, Jeffrey W

    2017-08-08

    understood process that is ubiquitous among Gram-negative organisms. Our group seeks to understand the biochemical mechanisms behind the formation of OMVs and has developed a model of small-molecule-induced membrane curvature as an important driver of this process. With this work, we demonstrate that PQS, a known small-molecule OMV inducer, must be exported to promote OMV biogenesis in both lab-adapted and clinical strains of Pseudomonas aeruginosa In supporting and expanding the bilayer-couple model of OMV biogenesis, the current work lays the groundwork for studying environmental and genetic factors that modulate OMV production and, consequently, the packaging and delivery of many bacterial factors. Copyright © 2017 Florez et al.

  19. Ionization-induced asymmetric self-phase modulation and universal modulational instability in gas-filled hollow-core photonic crystal fibers

    CERN Document Server

    Saleh, Mohammed F; Travers, John C; Russell, Philip St J; Biancalana, Fabio

    2012-01-01

    We study theoretically the propagation of relatively long pulses with ionizing intensities in a hollow-core photonic crystal fiber filled with a Raman-inactive gas. Due to photoionization, previously unknown types of asymmetric self-phase modulation and `universal' modulational instabilities existing in both normal and anomalous dispersion regions appear. We also show that it is possible to spontaneously generate a plasma-induced continuum of blueshifting solitons, opening up new possibilities for pushing supercontinuum generation towards shorter and shorter wavelengths.

  20. A Subset of Membrane-Altering Agents and γ-Secretase Modulators Provoke Nonsubstrate Cleavage by Rhomboid Proteases

    Directory of Open Access Journals (Sweden)

    Siniša Urban

    2014-09-01

    Full Text Available Rhomboid proteases are integral membrane enzymes that regulate cell signaling, adhesion, and organelle homeostasis pathways, making substrate specificity a key feature of their function. Interestingly, we found that perturbing the membrane pharmacologically in living cells had little effect on substrate processing but induced inappropriate cleavage of nonsubstrates by rhomboid proteases. A subclass of drugs known to modulate γ-secretase activity acted on the membrane directly and induced nonsubstrate cleavage by rhomboid proteases but left true substrate cleavage sites unaltered. These observations highlight an active role for the membrane in guiding rhomboid selectivity and caution that membrane-targeted drugs should be evaluated for cross-activity against membrane-resident enzymes that are otherwise unrelated to the intended drug target. Furthermore, some γ-secretase-modulating activity or toxicity could partly result from global membrane effects.

  1. Design and implementation of the optical fiber control and transmission module in multi-channel broadband digital receiver

    Science.gov (United States)

    Zhao, Ying-xiao; Zhang, Yue; Fan, Li-jie; Li, Wei-xing; Chen, Zeng-ping

    2014-09-01

    An optical fiber control and transmission module is designed and realized based on Virtex-7 field programmable gata array (FPGA), which can be applied in multi-channel broadband digital receivers. The module consists of sampling data transfer submodule and multi-channel synchronous sampling control submodule. The sampling data transmission in 4× fiber link channel is realized with the self-defined transfer protocol. The measured maximum data rate is 4.97 Gbyte/s. By connecting coherent clocks to the transmitter and receiver endpoints and using the self-defined transfer protocol, multi-channel sampling control signals transferred in optical fibers can be received synchronously by each analog-to-digital converter (ADC) with high accuracy and strong anti-interference ability. The module designed in this paper has certain reference value in increasing the transmission bandwidth and the synchronous sampling accuracy of multi-channel broadband digital receivers.

  2. On Neuron Membrane Potential Distributions for Voltage and Time Dependent Current Modulation

    Science.gov (United States)

    Salig, J. B.; Carpio-Bernido, M. V.; Bernido, C. C.; Bornales, J. B.

    Tracking variations of neuronal membrane potential in response to multiple synaptic inputs remains an important open field of investigation since information about neural network behavior and higher brain functions can be inferred from such studies. Much experimental work has been done, with recent advances in multi-electrode recordings and imaging technology giving exciting results. However, experiments have also raised questions of compatibility with available theoretical models. Here we show how methods of modern infinite dimensional analysis allow closed form expressions for important quantities rich in information such as the conditional probability density (cpd). In particular, we use a Feynman integral approach where fluctuations in the dynamical variable are parametrized with Hida white noise variables. The stochastic process described then gives variations in time of the relative membrane potential defined as the difference between the neuron membrane and firing threshold potentials. We obtain the cpd for several forms of current modulation coefficients reflecting the flow of synaptic currents, and which are analogous to drift coefficients in the configuration space Fokker-Planck equation. In particular, we consider cases of voltage and time dependence for current modulation for periodic and non-periodic oscillatory current modulation described by sinusoidal and Bessel functions.

  3. A novel anaerobic electrochemical membrane bioreactor (AnEMBR) with conductive hollow-fiber membrane for treatment of low-organic strength solutions

    KAUST Repository

    Katuri, Krishna

    2014-11-04

    A new anaerobic treatment system that combined a microbial electrolysis cell (MEC) with membrane filtration using electrically conductive, porous, nickel-based hollow-fiber membranes (Ni-HFMs) was developed to treat low organic strength solution and recover energy in the form of biogas. This new system is called an anaerobic electrochemical membrane bioreactor (AnEMBR). The Ni-HFM served the dual function as the cathode for hydrogen evolution reaction (HER) and the membrane for filtration of the effluent. The AnEMBR system was operated for 70 days with synthetic acetate solution having a chemical oxygen demand (COD) of 320 mg/L. Removal of COD was >95% at all applied voltages tested. Up to 71% of the substrate energy was recovered at an applied voltage of 0.7 V as methane rich biogas (83% CH4; < 1% H2) due to biological conversion of the hydrogen evolved at the cathode to methane. A combination of factors (hydrogen bubble formation, low cathode potential and localized high pH at the cathode surface) contributed to reduced membrane fouling in the AnEMBR compared to the control reactor (open circuit voltage). The net energy required to operate the AnEMBR system at an applied voltage of 0.7 V was significantly less (0.27 kWh/m3) than that typically needed for wastewater treatment using aerobic membrane bioreactors (1-2 kWh/m3).

  4. Methanothermobacter thermautotrophicus modulates its membrane lipids in response to hydrogen and nutrient availability

    Science.gov (United States)

    Yoshinaga, Marcos Y.; Gagen, Emma J.; Wörmer, Lars; Broda, Nadine K.; Meador, Travis B.; Wendt, Jenny; Thomm, Michael; Hinrichs, Kai-Uwe

    2015-01-01

    Methanothermobacter thermautotrophicus strain ΔH is a model hydrogenotrophic methanogen, for which extensive biochemical information, including the complete genome sequence, is available. Nevertheless, at the cell membrane lipid level, little is known about the responses of this archaeon to environmental stimuli. In this study, the lipid composition of M. thermautotrophicus was characterized to verify how this archaeon modulates its cell membrane components during growth phases and in response to hydrogen depletion and nutrient limitation (potassium and phosphate). As opposed to the higher abundance of phospholipids in the stationary phase of control experiments, cell membranes under nutrient, and energy stress were dominated by glycolipids that likely provided a more effective barrier against ion leakage. We also identified particular lipid regulatory mechanisms in M. thermautotrophicus, which included the accumulation of polyprenols under hydrogen-limited conditions and an increased content of sodiated adducts of lipids in nutrient-limited cells. These findings suggest that M. thermautotrophicus intensely modulates its cell membrane lipid composition to cope with energy and nutrient availability in dynamic environments. PMID:25657645

  5. Methanothermobacter thermautotrophicus modulates its membrane lipids in response to hydrogen and nutrient availability

    Directory of Open Access Journals (Sweden)

    Marcos Yukio Yoshinaga

    2015-01-01

    Full Text Available Methanothermobacter thermautotrophicus strain ∆H is a model hydrogenotrophic methanogen, for which extensive biochemical information, including the complete genome sequence, is available. Nevertheless, at the cell membrane lipid level, little is known about the responses of this archaeon to environmental stimuli. In this study, the lipid composition of M. thermautotrophicus was characterized to verify how this archaeon modulates its cell membrane components during growth phases and in response to hydrogen depletion and nutrient limitation (potassium and phosphate. As opposed to the higher abundance of phospholipids in the stationary phase of control experiments, cell membranes under nutrient and energy stress were dominated by glycolipids that likely provided a more effective barrier against ion leakage. We also identified particular lipid regulatory mechanisms in M. thermautotrophicus, which included the accumulation of polyprenols under hydrogen-limited conditions and an increased content of sodiated adducts of lipids in nutrient-limited cells. These findings suggest that M. thermautotrophicus intensely modulates its cell membrane lipid composition to cope with energy and nutrient availability in dynamic environments.

  6. Water reclamation from emulsified oily wastewater via effective forward osmosis hollow fiber membranes under the PRO mode.

    Science.gov (United States)

    Han, Gang; de Wit, Jos S; Chung, Tai-Shung

    2015-09-15

    By using a novel hydrophilic cellulose acetate butyrate (CAB) as the membrane material for the hollow fiber substrate and modifying its outer surface by polydopamine (PDA) coating and inner surface by interfacial polymerization, we have demonstrated that the thin-film composite (TFC) membranes can be effectively used for sustainable water reclamation from emulsified oil/water streams via forward osmosis (FO) under the pressure retarded osmosis (PRO) mode. The newly developed TFC-FO hollow fiber membrane shows characteristics of high water flux, outstanding salt and oil rejection, and low fouling propensity. Under the PRO mode, the newly developed TFC-FO membrane exhibits a water flux of 37.1 L m(-2) h(-1) with an oil rejection of 99.9% using a 2000 ppm soybean oil/water emulsion as the feed and 1 M NaCl as the draw solution. Remarkable anti-fouling behaviors have also been observed. Under the PRO mode, the water flux decline is only 10% of the initial value even after a 12 h test for oil/water separation. The water flux of the fouled membrane can be effectively restored to 97% of the original value by water rinses on the fiber outer surface without using any chemicals. Furthermore, the flux declines are only 25% and 52% when the water recovery of a 2000 ppm soybean oil/water emulsion and a 2000 ppm petroleum oil/water emulsion containing 0.04 M NaCl reaches 82%, respectively. This study may not only provide insightful guidelines for the fabrication of effective TFC-FO membranes with high performance and low fouling behaviors for oily wastewater under the PRO mode but also add an alternative perspective to the design of new materials for water purification purposes.

  7. Enhanced mechanical properties and cytocompatibility of electrospun poly(L-lactide) composite fiber membranes assisted by polydopamine-coated halloysite nanotubes

    Energy Technology Data Exchange (ETDEWEB)

    Luo, Chuang; Zou, Ziping [Biomaterial Research Laboratory, Department of Material Science and Engineering, College of Science and Engineering, Jinan University, Guangzhou 510632 (China); Luo, Binghong, E-mail: tluobh@jnu.edu.cn [Biomaterial Research Laboratory, Department of Material Science and Engineering, College of Science and Engineering, Jinan University, Guangzhou 510632 (China); Engineering Research Center of Artificial Organs and Materials, Ministry of Education, Guangzhou 510632 (China); Wen, Wei [Biomaterial Research Laboratory, Department of Material Science and Engineering, College of Science and Engineering, Jinan University, Guangzhou 510632 (China); Engineering Research Center of Artificial Organs and Materials, Ministry of Education, Guangzhou 510632 (China); Li, Huihua [Biomaterial Research Laboratory, Department of Material Science and Engineering, College of Science and Engineering, Jinan University, Guangzhou 510632 (China); Liu, Mingxian [Biomaterial Research Laboratory, Department of Material Science and Engineering, College of Science and Engineering, Jinan University, Guangzhou 510632 (China); Engineering Research Center of Artificial Organs and Materials, Ministry of Education, Guangzhou 510632 (China); Zhou, Changren, E-mail: tcrz9@jnu.edu.cn [Biomaterial Research Laboratory, Department of Material Science and Engineering, College of Science and Engineering, Jinan University, Guangzhou 510632 (China); Engineering Research Center of Artificial Organs and Materials, Ministry of Education, Guangzhou 510632 (China)

    2016-04-30

    Graphical abstract: - Highlights: • D-HNTs was prepared by a facile approach based on the self-polymerization of DOPA. • The D-HNTs can disperse more uniformly in PLLA matrix than untreated HNTs. • The interfacial adhesion between D-HNTs and PLLA matrix was obviously improved. • D-HNTs/PLLA fiber membrane has better tensile properties compared with HNTs/PLLA. • The D-HNTs/PLLA fiber membrane is favorable to cell adhesion and proliferation. - Abstract: To improve the dispersion and interfacial interaction between halloysite nanotubes (HNTs) and poly(L-lactide) (PLLA) matrix, and hence to increase the mechanical properties and cytocompatibility of the HNTs/PLLA composite, a facile approach was developed to prepare polydopamine-coated HNTs (D-HNTs) by the self-polymerization of dopamine (DOPA), and then HNTs and D-HNTs were further introduced into PLLA matrix to fabricate HNTs/PLLA and D-HNTs/PLLA fiber membranes based on electrospinning technique. The successful immobilization of the polydopamine (PDOPA) coating on the surfaces of HNTs was confirmed, and such PDOPA coating played an important role in improving the interfacial interaction between the nanotubes and PLLA matrix. The D-HNTs were dispersed in the matrix more uniformly than untreated HNTs, and relative smooth and uniform fiber were obtained for the D-HNTs/PLLA fiber membrane. As a result, the tensile strength and modulus of the D-HNTs/PLLA fiber membrane were obviously superior to those of the HNTs/PLLA fiber membrane. Cell culture results revealed that D-HNTs/PLLA fiber membrane was more effectively to promote MC3T3-E1 cells adhesion and proliferation than neat PLLA and HNTs/PLLA fiber membrane.

  8. Enhanced mechanical properties and cytocompatibility of electrospun poly(L-lactide) composite fiber membranes assisted by polydopamine-coated halloysite nanotubes

    Science.gov (United States)

    Luo, Chuang; Zou, Ziping; Luo, Binghong; Wen, Wei; Li, Huihua; Liu, Mingxian; Zhou, Changren

    2016-04-01

    To improve the dispersion and interfacial interaction between halloysite nanotubes (HNTs) and poly(L-lactide) (PLLA) matrix, and hence to increase the mechanical properties and cytocompatibility of the HNTs/PLLA composite, a facile approach was developed to prepare polydopamine-coated HNTs (D-HNTs) by the self-polymerization of dopamine (DOPA), and then HNTs and D-HNTs were further introduced into PLLA matrix to fabricate HNTs/PLLA and D-HNTs/PLLA fiber membranes based on electrospinning technique. The successful immobilization of the polydopamine (PDOPA) coating on the surfaces of HNTs was confirmed, and such PDOPA coating played an important role in improving the interfacial interaction between the nanotubes and PLLA matrix. The D-HNTs were dispersed in the matrix more uniformly than untreated HNTs, and relative smooth and uniform fiber were obtained for the D-HNTs/PLLA fiber membrane. As a result, the tensile strength and modulus of the D-HNTs/PLLA fiber membrane were obviously superior to those of the HNTs/PLLA fiber membrane. Cell culture results revealed that D-HNTs/PLLA fiber membrane was more effectively to promote MC3T3-E1 cells adhesion and proliferation than neat PLLA and HNTs/PLLA fiber membrane.

  9. Absorption-Modulated Crossed-Optical Fiber-Sensor Platform for Measurements in Liquid Environments and Flow Streams

    Directory of Open Access Journals (Sweden)

    Paul E. Henning

    2017-01-01

    Full Text Available A new evanescent-wave fiber sensor is described that utilizes absorption-modulated luminescence (AML in combination with a crossed-fiber sensor platform. The luminescence signals of two crossed-fiber reference regions, placed on opposite sides of the stretch of fiber supporting the absorbance sensor, monitor the optical intensity in the fiber core. Evanescent absorption of the sensor reduces a portion of the excitation light and modulates the luminescence of the second reference region. The attenuation is determined from the luminescence intensity of both reference regions similar to the Beer-Lambert Law. The AML-Crossed-Fiber technique was demonstrated using the absorbance of the Zn(II-PAN2 complex at 555 nm. A linear response was obtained over a zinc(II concentration range of 0 to 20 μM (approximately 0 to 1.3 ppm. A nonlinear response was observed at higher zinc(II concentrations and was attributed to depletion of higher-order modes in the fiber. This was corroborated by the measured induced repopulation of these modes.

  10. Preparation of Sulfobetaine-Grafted PVDF Hollow Fiber Membranes with a Stably Anti-Protein-Fouling Performance

    Directory of Open Access Journals (Sweden)

    Qian Li

    2014-04-01

    Full Text Available Based on a two-step polymerization method, two sulfobetaine-based zwitterionic monomers, including 3-(methacryloylamino propyl-dimethyl-(3-sulfopropyl ammonium hydroxide (MPDSAH and 2-(methacryloyloxyethyl ethyl-dimethyl-(3-sulfopropyl ammonium (MEDSA, were successfully grafted from poly(vinylidene fluoride (PVDF hollow fiber membrane surfaces in the presence of N,N′-methylene bisacrylamide (MBAA as a cross-linking agent. The mechanical properties of the PVDF membrane were improved by the zwitterionic surface layers. The surface hydrophilicity of PVDF membranes was significantly enhanced and the polyMPDSAH-g-PVDF membrane showed a higher hydrophilicity due to the higher grafting amount. Compared to the polyMEDSA-g-PVDF membrane, the polyMPDSAH-g-PVDF membrane showed excellent significantly better anti-protein-fouling performance with a flux recovery ratio (RFR higher than 90% during the cyclic filtration of a bovine serum albumin (BSA solution. The polyMPDSAH-g-PVDF membrane showed an obvious electrolyte-responsive behavior and its protein-fouling-resistance performance was improved further during the filtration of the protein solution with 100 mmol/L of NaCl. After cleaned with a membrane cleaning solution for 16 days, the grafted MPDSAH layer on the PVDF membrane could be maintain without any chang; however, the polyMEDSA-g-PVDF membrane lost the grafted MEDSA layer after this treatment. Therefore, the amide group of sulfobetaine, which contributed significantly to the higher hydrophilicity and stability, was shown to be imperative in modifying the PVDF membrane for a stable anti-protein-fouling performance via the two-step polymerization method.

  11. Analysis of the Crosstalk in WDM Systems Caused by Cross-phase Modulation in Erbium-doped Fiber Amplifiers

    Institute of Scientific and Technical Information of China (English)

    LIU Ning; LIAO Changjun; LIU Songhao; GUO Qi; XU Wengchen

    2001-01-01

    The crosstalk in WDM systems caused by cross-phase modulation (XPM) in erbium-doped fiber amplifiers(EDFA) was studied analytically. The results confirm that the EDFA induced phase shift does cause crosstalk in WDM systems. The crosstalk between two channels both with modulated pulse signals is studied for the first time. It was found that the EDFA induced phase shift will cause serious deterioration of the eye diagram when the optical signals continue to travel in the normal-dispersion regime of the transmission fiber, while in the anomalous-dispersion regime this phase shift will not cause much deterioration of the eye diagram.

  12. Compact multiple laser beam scanning module for high-resolution pico-projector applications using a fiber bundle combiner

    Science.gov (United States)

    Ide, Masafumi; Fukaya, Shinpei; Yoda, Kaoru; Suzuki, Masaya

    2014-02-01

    We present a novel multiple laser beam scanning projection module using compact red-green-blue (RGB) fiber pigtailed laser modules for use in a high resolution pico-projector display system using a fiber bundle combiner in combination with a single MEMS mirror. This system can be used to create accurate multiple-projection images on a screen without overlaps or spaces among the projection images. The system uses very simple projection optics and has the potential to become a light engine unit for use in multiple projection systems, particularly those for light field displays. As such, light field display applications are also discussed.

  13. Vacuumed gap membrane distillation (vagmed) module, multi-stage vagmed systems, and vagmed processes

    KAUST Repository

    Ghaffour, Noreddine

    2016-06-30

    Vacuumed gap membrane distillation (VAGMED) modules, and multi-stage VAGMED systems and processes using the modules are provided. In an embodiment, the membrane distillation modules (10) can comprise: a) a condenser (12) including a condensation surface (15); b) a first passageway (13) having an inlet for receiving a first feed stream (14) and an outlet through which the first stream can pass out of the first passageway, the first passageway configured to bring the first feed stream into thermal communication with the condensation surface; c) an evaporator (17) including a permeable evaporation surface allowing condensable gas to pass there through; d) a second passageway (18) having an inlet for receiving a second feed stream (19) and an outlet through which the second feed stream can pass out of the second passageway, the second passageway configured to bring the second feed stream into communication with the permeable evaporation surface; and e) an enclosure (24) providing a vacuum compartment within which the condenser, the evaporator and the first and second passageways of the module are contained.

  14. Lipid domains in intact fiber-cell plasma membranes isolated from cortical and nuclear regions of human eye lenses of donors from different age groups.

    Science.gov (United States)

    Raguz, Marija; Mainali, Laxman; O'Brien, William J; Subczynski, Witold K

    2015-03-01

    The results reported here clearly document changes in the properties and the organization of fiber-cell membrane lipids that occur with age, based on electron paramagnetic resonance (EPR) analysis of lens membranes of clear lenses from donors of age groups from 0 to 20, 21 to 40, and 61 to 80 years. The physical properties, including profiles of the alkyl chain order, fluidity, hydrophobicity, and oxygen transport parameter, were investigated using EPR spin-labeling methods, which also provide an opportunity to discriminate coexisting lipid domains and to evaluate the relative amounts of lipids in these domains. Fiber-cell membranes were found to contain three distinct lipid environments: bulk lipid domain, which appears minimally affected by membrane proteins, and two domains that appear due to the presence of membrane proteins, namely boundary and trapped lipid domains. In nuclear membranes the amount of boundary and trapped phospholipids as well as the amount of cholesterol in trapped lipid domains increased with the donors' age and was greater than that in cortical membranes. The difference between the amounts of lipids in domains uniquely formed due to the presence of membrane proteins in nuclear and cortical membranes increased with the donors' age. It was also shown that cholesterol was to a large degree excluded from trapped lipid domains in cortical membranes. It is evident that the rigidity of nuclear membranes was greater than that of cortical membranes for all age groups. The amount of lipids in domains of low oxygen permeability, mainly in trapped lipid domains, were greater in nuclear than cortical membranes and increased with the age of donors. These results indicate that the nuclear fiber cell plasma membranes were less permeable to oxygen than cortical membranes and become less permeable to oxygen with age. In clear lenses, age-related changes in the lens lipid and protein composition and organization appear to occur in ways that increase fiber

  15. Spinning process variables and polymer solution effects in the die-swell phenomenon during hollow fiber membranes formation

    Directory of Open Access Journals (Sweden)

    Pereira C.C.

    2000-01-01

    Full Text Available During hollow fiber spinning many variables are involved whose effects are still not completely clear. However, its understanding is of great interest because the control of these variables may originate membranes with the desired morphologies and physical properties. In this work, the phase inversion process induced by the immersion precipitation technique was applied to prepare hollow fibers membranes. It was verified that some of the variables involved, can promote a visco-elastic polymer solution expansion, called die-swell phenomenon, which is undesired since it may lead to low reproducibility of the permeation properties. The effects of the distance between spinneret and precipitation bath, the bore liquid composition, and the polymer solution composition were analyzed and discussed in order to avoid this phenomenon. According to the results, it was verified that the parameters investigated might promote a delay precipitation, which restrained the visco-elastic expansion.

  16. Quercetin modulates activities of Taiwan cobra phospholipase A2 via its effects on membrane structure and membrane-bound mode of phospholipase A2

    Indian Academy of Sciences (India)

    Yi-Ling Chiou; Shinne-Ren Lin; Wan-Ping Hu; Long-Sen Chang

    2012-06-01

    The goal of the present study is to elucidate the mechanism of quercetin on modulating Naja naja atra phospholipase A2 (PLA2) activities. Sphingomyelin inhibited PLA2 enzymatic activity and membrane-damaging activity against egg yolk phosphatidylcholine (EYPC), while cholesterol and quercetin abrogated the sphingomeyelin inhibitory effect. Quercetin incorporation led to a reduction in PLA2 enzymatic activity and membrane-damaging activity toward EYPC/sphingomyelin/cholesterol vesicles. Both cholesterol and quercetin increased detergent resistance and reduced membrane fluidity of EYPC/sphingomyelin vesicles. Quercetin reduced detergent insolubility but increased ordered lipid packing of EYPC/sphingomyelin/cholesterol vesicles. Acrylamide quenching studies and trinitrophenylation of Lys residues revealed that quercetin altered the membrane-bound mode of PLA2 differently upon absorption onto the membrane bilayers of different lipid compositions. However, 8-anilinonaphthalene sulphonate-binding assay revealed that quercetin marginally affected the interaction between active site of PLA2 with phospholipid vesicles. Collectively, our data indicate that membrane-inserted quercetin modulates PLA2 interfacial activity and membrane-damaging activity via its effects on membrane structure and membrane-bound mode of PLA2.

  17. Hydrodynamic Study of a Hollow Fiber Membrane System Using Experimental and Numerical Derived Surface Shear Stresses

    DEFF Research Database (Denmark)

    Ratkovich, Nicolas Rios; Hunze, M.; Nopens, I.

    2012-01-01

    : 0.25 – 0.49 Pa) with an error of less than 5 %; (ii) high shear stresses (i.e. 90th percentile) predictions were much less accurate (model: 0.60 – 1.23 Pa; experimental: 1.04 – 1.90 Pa) with an error up to 38 %. This was attributed to the fact that the CFD model only considers the two-phase flow (50......Computational Fluids Dynamics (CFD) models can be used to gain insight into the shear stresses induced by air sparging on submerged hollow fiber Membrane BioReactor (MBR) systems. It was found that the average range of shear stresses obtained by the CFD model (0.30 – 0.60 Pa) and experimentally (0.......39 – 0.69 Pa) were in good agreement, with an error less that 15 %. Based on comparison of the cumulative frequency distribution of shear stresses from experiments and simulation: (i) moderate shear stresses (i.e. 50th percentile) were found to be accurately predicted (model: 0.24 – 0.45 Pa; experimental...

  18. Hollow-fiber membrane bioreactor for the treatment of high-strength landfill leachate

    KAUST Repository

    Rizkallah, Marwan

    2013-07-15

    Performance assessment of membrane bioreactor (MBR) technology for the treatability of high-strength landfill leachate is relatively limited or lacking. This study examines the feasibility of treating high-strength landfill leachate using a hollow-fiber MBR. For this purpose, a laboratory-scale MBR was constructed and operated to treat leachate with a chemical oxygen demand (COD) of 9000-11,000 mg/l, a 5-day biochemical oxygen demand (BOD5) of 4000-6,000 mg/l, volatile suspended solids (VSS) of 300-500 mg/l, total nitrogen (TN) of 2000-6000 mg/l, and an ammonia-nitrogen (NH3-N) of 1800-4000 mg/l. VSS was used with the BOD and COD data to simulate the biological activity in the activated sludge. Removal efficiencies > 95-99% for BOD5, VSS, TN and NH3-N were attained. The coupled experimental and simulation results contribute in filling a gap in managing high-strength landfill leachate and providing guidelines for corresponding MBR application. © The Author(s) 2013.

  19. Dystrophin and utrophin influence fiber type composition and post-synaptic membrane structure.

    Science.gov (United States)

    Rafael, J A; Townsend, E R; Squire, S E; Potter, A C; Chamberlain, J S; Davies, K E

    2000-05-22

    The X-linked muscle wasting disease Duchenne muscular dystrophy is caused by the lack of dystrophin in muscle. Protein structure predictions, patient mutations, in vitro binding studies and transgenic and knockout mice suggest that dystrophin plays a mechanical role in skeletal muscle, linking the subsarcolemmal cytoskeleton with the extracellular matrix through its direct interaction with the dystrophin-associated protein complex (DAPC). Although a signaling role for dystrophin has been postulated, definitive data have been lacking. To identify potential non-mechanical roles of dystrophin, we tested the ability of various truncated dystrophin transgenes to prevent any of the skeletal muscle abnormalities associated with the double knockout mouse deficient for both dystrophin and the dystrophin-related protein utrophin. We show that restoration of the DAPC with Dp71 does not prevent the structural abnormalities of the post-synaptic membrane or the abnormal oxidative properties of utrophin/dystrophin-deficient muscle. In marked contrast, a dystrophin protein lacking the cysteine-rich domain, which is unable to prevent dystrophy in the mdx mouse, is able to ameliorate these abnormalities in utrophin/dystrophin-deficient mice. These experiments provide the first direct evidence that in addition to a mechanical role and relocalization of the DAPC, dystrophin and utrophin are able to alter both structural and biochemical properties of skeletal muscle. In addition, these mice provide unique insights into skeletal muscle fiber type composition.

  20. Hemocompatibility evaluation of small elastomeric hollow fiber membranes as vascular substitutes.

    Science.gov (United States)

    Mercado-Pagán, Ángel E; Ker, Dai Fei Elmer; Yang, Yunzhi

    2014-10-01

    One of the main challenges for clinical implementation of small diameter vascular grafts (SDVGs) is their limited hemocompatibility. Important design specifications for such grafts include features that minimize the long-term risks of restenosis, fouling, and thrombus formation. In our lab, we have developed elastomeric hollow fiber membranes (HFMs), using a phase inversion method, as candidates for SDVGs. Here, we present our results for in vitro hemocompatibility testing of our HFM under flow and static conditions. Our results showed that the polymer-based HFMs do not damage the integrity of human red blood cells (RBCs) as shown by their low hemolytic extent (less than 2%). When analyzed for blood cell lysis using lactate dehydrogenase (LDH) activity as an indicator, no significant differences were observed between blood exposed to our HFMs and uncoagulated blood. Analysis of protein adsorption showed a low concentration of proteins deposited on the surfaces of HFM after 24 h. Platelet adhesion profiles using human platelet-rich plasma (PRP) showed that a low level of platelets adhered to the HFMs after 24 h, indicating minimal thrombotic potential. Under the majority of conditions, no significant differences were observed between medical-grade polymers and our HFMs. Eventual optimization of hemocompatible elastomeric HFM vessel grafts could lead to improved tissue vascularization as well as vascularized, tissue-engineered scaffolds for organ repair.

  1. Multi-objective Optimization of Solar-driven Hollow-fiber Membrane Distillation Systems.

    Energy Technology Data Exchange (ETDEWEB)

    Nenoff, Tina M.; Moore, S.; Mirchandani, S.; Karanikola, V.; Arnold, R.; Saez, E.

    2017-09-01

    Securing additional water sources remains a primary concern for arid regions in both the developed and developing world. Climate change is causing fluctuations in the frequency and duration of precipitation, which can be can be seen as prolonged droughts in some arid areas. Droughts decrease the reliability of surface water supplies, which forces communities to find alternate primary water sources. In many cases, ground water can supplement the use of surface supplies during periods of drought, reducing the need for above-ground storage without sacrificing reliability objectives. Unfortunately, accessible ground waters are often brackish, requiring desalination prior to use, and underdeveloped infrastructure and inconsistent electrical grid access can create obstacles to groundwater desalination in developing regions. The objectives of the proposed project are to (i) mathematically simulate the operation of hollow fiber membrane distillation systems and (ii) optimize system design for off-grid treatment of brackish water. It is anticipated that methods developed here can be used to supply potable water at many off-grid locations in semi-arid regions including parts of the Navajo Reservation. This research is a collaborative project between Sandia and the University of Arizona.

  2. Hydrodynamic Study of a Hollow Fiber Membrane System Using Experimental and Numerical Derived Surface Shear Stresses

    DEFF Research Database (Denmark)

    Ratkovich, Nicolas Rios; Hunze, M.; Nopens, I.

    2012-01-01

    Computational Fluids Dynamics (CFD) models can be used to gain insight into the shear stresses induced by air sparging on submerged hollow fiber Membrane BioReactor (MBR) systems. It was found that the average range of shear stresses obtained by the CFD model (0.30 – 0.60 Pa) and experimentally (0.......39 – 0.69 Pa) were in good agreement, with an error less that 15 %. Based on comparison of the cumulative frequency distribution of shear stresses from experiments and simulation: (i) moderate shear stresses (i.e. 50th percentile) were found to be accurately predicted (model: 0.24 – 0.45 Pa; experimental......: 0.25 – 0.49 Pa) with an error of less than 5 %; (ii) high shear stresses (i.e. 90th percentile) predictions were much less accurate (model: 0.60 – 1.23 Pa; experimental: 1.04 – 1.90 Pa) with an error up to 38 %. This was attributed to the fact that the CFD model only considers the two-phase flow (50...

  3. A mammalian nervous-system-specific plasma membrane proteasome complex that modulates neuronal function.

    Science.gov (United States)

    Ramachandran, Kapil V; Margolis, Seth S

    2017-04-01

    In the nervous system, rapidly occurring processes such as neuronal transmission and calcium signaling are affected by short-term inhibition of proteasome function. It is unclear how proteasomes are able to acutely regulate such processes, as this action is inconsistent with their canonical role in proteostasis. Here we describe a mammalian nervous-system-specific membrane proteasome complex that directly and rapidly modulates neuronal function by degrading intracellular proteins into extracellular peptides that can stimulate neuronal signaling. This proteasome complex is closely associated with neuronal plasma membranes, exposed to the extracellular space, and catalytically active. Selective inhibition of the membrane proteasome complex by a cell-impermeable proteasome inhibitor blocked the production of extracellular peptides and attenuated neuronal-activity-induced calcium signaling. Moreover, we observed that membrane-proteasome-derived peptides were sufficient to induce neuronal calcium signaling. Our discoveries challenge the prevailing notion that proteasomes function primarily to maintain proteostasis, and highlight a form of neuronal communication that takes place through a membrane proteasome complex.

  4. Side chain hydrophobicity modulates therapeutic activity and membrane selectivity of antimicrobial peptide mastoparan-X.

    Directory of Open Access Journals (Sweden)

    Jonas R Henriksen

    Full Text Available The discovery of new anti-infective compounds is stagnating and multi-resistant bacteria continue to emerge, threatening to end the "antibiotic era". Antimicrobial peptides (AMPs and lipo-peptides such as daptomycin offer themselves as a new potential class of antibiotics; however, further optimization is needed if AMPs are to find broad use as antibiotics. In the present work, eight analogues of mastoparan-X (MPX were investigated, having side chain modifications in position 1, 8 and 14 to modulate peptide hydrophobicity. The self-association properties of the peptides were characterized, and the peptide-membrane interactions in model membranes were compared with the bactericidal and haemolytic properties. Alanine substitution at position 1 and 14 resulted in higher target selectivity (red blood cells versus bacteria, but also decreased bactericidal potency. For these analogues, the gain in target selectivity correlated to biophysical parameters showing an increased effective charge and reduction in the partitioning coefficient for membrane insertion. Introduction of an unnatural amino acid, with an octyl side chain by amino acid substitution, at positions 1, 8 and 14 resulted in increased bactericidal potency at the expense of radically reduced membrane target selectivity. Overall, optimized membrane selectivity or bactericidal potency was achieved by changes in side chain hydrophobicity of MPX. However, enhanced potency was achieved at the expense of selectivity and vice versa in all cases.

  5. Flame Retardancy Effects of Graphene Nanoplatelet/Carbon Nanotube Hybrid Membranes on Carbon Fiber Reinforced Epoxy Composites

    Directory of Open Access Journals (Sweden)

    Dongxian Zhuo

    2013-01-01

    Full Text Available Carbon nanotube/graphene nanoplatelet (MWCNT/GNP hybrid membranes with lower liquid permeability and better barrier effect compared to MWCNT membranes were successfully synthesized by vacuum filtering. Their morphologies, water permeability, and pore structures were characterized by a scanning electron microscope (SEM and nitrogen adsorption isotherms. Furthermore, MWCNT/GNP membranes were used to improve the flame retardancy of carbon fiber reinforced polymer (CFRP composites, and the influence of weight percentage of GNPs on the permeability and flame retardancy of MWCNT/GNP membranes was systematically investigated. Results show that incorporation of MWCNT/GNP membranes on CFRP composite plates can remarkably improve the flame retardancy of CFRP composites. Specifically, the incorporation of hierarchical MWCNT/GNP membrane with 7.5 wt% of GNP displays a 35% reduction in the peak heat release rate (PHRR for a CFRP composite plate with the epoxy as matrix and a 11% reduction in PHRR compared with the incorporation of MWCNT membrane only. A synergistic flame retarding mechanism is suggested to be attributed to these results, which includes controlling the pore size and penetrative network structure.

  6. Integrating nanohybrid membranes of reduced graphene oxide: chitosan: silica sol gel with fiber optic SPR for caffeine detection.

    Science.gov (United States)

    Kant, Ravi; Tabassum, Rana; Gupta, Banshi D

    2017-05-12

    Caffeine is the most popular psychoactive drug consumed in the world for improving alertness and enhancing wakefulness. However, caffeine consumption beyond limits can result in lot of physiological complications in human beings. In this work, we report a novel detection scheme for caffeine integrating nanohybrid membranes of reduced graphene oxide (rGO) in chitosan modified silica sol gel (rGO: chitosan: silica sol gel) with fiber optic surface plasmon resonance. The chemically synthesized nanohybrid membrane forming the sensing route has been dip coated over silver coated unclad central portion of an optical fiber. The sensor works on the mechanism of modification of dielectric function of sensing layer on exposure to analyte solution which is manifested in terms of red shift in resonance wavelength. The concentration of rGO in polymer network of chitosan and silica sol gel and dipping time of the silver coated probe in the solution of nanohybrid membrane have been optimized to extricate the supreme performance of the sensor. The optimized sensing probe possesses a reasonably good sensitivity and follows an exponentially declining trend within the entire investigating range of caffeine concentration. The sensor boasts of an unparalleled limit of detection value of 1.994 nM and works well in concentration range of 0-500 nM with a response time of 16 s. The impeccable sensor methodology adopted in this work combining fiber optic SPR with nanotechnology furnishes a novel perspective for caffeine determination in commercial foodstuffs and biological fluids.

  7. Integrating nanohybrid membranes of reduced graphene oxide: chitosan: silica sol gel with fiber optic SPR for caffeine detection

    Science.gov (United States)

    Kant, Ravi; Tabassum, Rana; Gupta, Banshi D.

    2017-05-01

    Caffeine is the most popular psychoactive drug consumed in the world for improving alertness and enhancing wakefulness. However, caffeine consumption beyond limits can result in lot of physiological complications in human beings. In this work, we report a novel detection scheme for caffeine integrating nanohybrid membranes of reduced graphene oxide (rGO) in chitosan modified silica sol gel (rGO: chitosan: silica sol gel) with fiber optic surface plasmon resonance. The chemically synthesized nanohybrid membrane forming the sensing route has been dip coated over silver coated unclad central portion of an optical fiber. The sensor works on the mechanism of modification of dielectric function of sensing layer on exposure to analyte solution which is manifested in terms of red shift in resonance wavelength. The concentration of rGO in polymer network of chitosan and silica sol gel and dipping time of the silver coated probe in the solution of nanohybrid membrane have been optimized to extricate the supreme performance of the sensor. The optimized sensing probe possesses a reasonably good sensitivity and follows an exponentially declining trend within the entire investigating range of caffeine concentration. The sensor boasts of an unparalleled limit of detection value of 1.994 nM and works well in concentration range of 0-500 nM with a response time of 16 s. The impeccable sensor methodology adopted in this work combining fiber optic SPR with nanotechnology furnishes a novel perspective for caffeine determination in commercial foodstuffs and biological fluids.

  8. Scale-up of osmotic membrane bioreactors by modeling salt accumulation and draw solution dilution using hollow-fiber membrane characteristics and operation conditions.

    Science.gov (United States)

    Kim, Suhan

    2014-08-01

    A full-scale osmotic membrane bioreactor (OMBR) model was developed to simulate salt accumulation, draw solution (DS) dilution, and water flux over the hollow-fiber membrane length. The model uses the OMBR design parameters, DS properties, and forward osmosis (FO) membrane characteristics obtained from lab-scale tests. The modeling results revealed a tremendous water flux decline (10→0.82LMH) and short solids retention time (SRT: 5days) due to salt accumulation and DS dilution when OMBR is scaled up using commercially available DS and FO membrane. Simulated water flux is a result of interplay among reverse salt flux, internal and external concentration polarization (ICP and ECP). ECP adversely impacts water flux considerably in full-scale OMBR although it is often ignored in previous works. The OMBR model makes it possible to select better DS properties (higher flow rate and salt concentration) and FO membranes with higher water flux propensity in full-scale operation. Copyright © 2014 Elsevier Ltd. All rights reserved.

  9. Effect of Extractant and Cold-drawing on the Structure and Performance of HDPE Hollow Fiber Membranes Fabricated via Thermally Induced Phase Separation Method

    Institute of Scientific and Technical Information of China (English)

    WANG Jian-li; RUAN Wen-xiang; SONG Yi-lin; JI Jian-bing; YAO Ke-jian

    2006-01-01

    Microporous polyolefin hollow fiber membranes were prepared from high density polyethylene (HDPE)-paraffin solution via thermally induced phase separation (TIPS)method. Effects of extraction and cold-drawing condition on membrane structure and performance were investigated.Five volatile solvents were used as extractant. Dimension of hollow fiber and gas permeation rate of membrane were measured. Microstructure of membrane was examined by Scanning Electronic Microscope (SEM). The results show that the membrane treated by pentane possesses a higher porosity, nitrogen permeability and lower shrinkage than those of membranes extracted by other three extractants. It is also found that thc membrane stretched 133% shows the highest porosity and gas permeability in this study.

  10. Loop-locked coherent population trapping magnetometer based on a fiber electro-optic modulator.

    Science.gov (United States)

    Hu, Yong; Feng, Y Y; Xu, Chi; Xue, H B; Sun, Li

    2014-04-01

    We have set up a coherent population trapping (CPT)-based magnetometer prototype with the D1 line of ⁸⁷Rb atoms. The dichromatic light field is derived from a fiber electro-optic modulator (FEOM) connected to an external cavity laser diode. A CPT resonance signal with a 516 Hz linewidth is observed. By feeding back the derivative of the resonance curve to the FEOM with a proportional integral controller, of which the voltage output is directly converted to the measured magnetic field intensity, the resonance peak is locked to the environmental magnetic field. The measurement data we have achieved are well matched with the data measured by a commercial fluxgate magnetometer within 2 nT, and the sensitivity is better than 8 pT/√Hz in a parallel B field.

  11. Fiber Bragg-grating strain sensor interrogation using laser radio-frequency modulation.

    Science.gov (United States)

    Gagliardi, G; Salza, M; Ferraro, P; De Natale, P

    2005-04-04

    We demonstrate the possibility of using radio-frequency modulation spectroscopic techniques for interrogation of fiber Bragg-grating (FBG) structures. Sidebands at 2 GHz are superimposed onto the output spectrum of a 1560-nm DFB diode laser. The power reflected by an FBG is demodulated at multiples of the sideband frequency. The sideband-to-carrier beat signal is shown to be extremely sensitive to Bragg wavelength shifts due to mechanical stress. Using this method, both static and dynamic strain measurements can be performed, with a noise-equivalent sensitivity of the order of 150 nepsilon/ radicalHz, in the quasi-static domain (2 Hz), and 1.6 nepsilon/ radicalHz at higher frequencies (1 kHz). The measured frequency response is presently limited at 20 kHz only by the test device bandwidth. A long-term reproducibility in strain measurements within 100 nepsilon is estimated from laser frequency drift referred to molecular absorption lines.

  12. In vivo BDNF modulation of hippocampal mossy fiber plasticity induced by high frequency stimulation.

    Science.gov (United States)

    Schjetnan, Andrea Gómez-Palacio; Escobar, Martha L

    2012-01-01

    Changes in synaptic efficacy and morphology have been proposed as mechanisms underlying learning and memory processes. In our previous studies, high frequency stimulation (HFS) sufficient to induce LTP at the hippocampal mossy fiber (MF) pathway, leads to MF synaptogenesis, in a prominent contralateral form, at the stratum oriens of hippocampal CA3 area. Recently we reported that acute intrahippocampal microinfusion of BDNF induces a lasting potentiation of synaptic efficacy at the MF projection accompanied by a structural reorganization at the CA3 area within the stratum oriens region in a prominent ipsilateral form. It is considered that the capacity of synapses to express plastic changes is itself subject to variation dependent on previous experience. Here we used intrahippocampal microinfusion of BDNF to analyze its effects on functional and structural synaptic plasticity induced by subsequent mossy fiber HFS sufficient to induce LTP in adult rats, in vivo. Our results show that BDNF modifies the ability of the MF pathway to present LTP by HFS. Moreover BDNF modified the structural reorganization pattern produced by HFS, presenting a balanced bilateral appearance. Microinfusion of K252a blocks the functional and morphological effects produced by BDNF, revealing that the BDNF modulation is dependent on its TrkB receptor activation. These findings support the idea that BDNF actions modify subsequent synaptic plasticity; a homeostatic mechanism thought to be essential for synaptic integration among prolonged temporal domains in the adult mammalian brain.

  13. High-efficiency Q-switched erbium fiber laser using a Bragg grating-based modulator

    Science.gov (United States)

    Russo, N. A.; Duchowicz, R.; Mora, J.; Cruz, J. L.; Andrés, M. V.

    2002-09-01

    In this work we analyze the behavior of an erbium-doped fiber laser which is based on a simple scheme. Excitation of the active medium is performed in the 980 nm pump band with a CW semiconductor laser source. Two fiber Bragg gratings acting as mirrors of the Fabry-Perot laser cavity were used. One of these gratings was mounted over a piezoelectric (PZT) element. By applying voltage pulses to the piezoelectric, the laser cavity was temporally modulated and Q-switched laser pulses up to 530 mW peak powers at 3 kHz were obtained. Typical laser emission of 2-3 μs temporal widths and 0.1 nm of optical bandwidth have been achieved when the system was operated at 18.5 kHz repetition rates. Different behaviors were observed depending on the pumping level of the active medium and on the amplitude and frequency of the signal applied on the PZT. Q-switched laser output, in the erbium spectral gain region, with high laser efficiency of energy conversion was generated. Pumping at 76 mW and operating the laser at 18.5 kHz, an efficiency of 26% was obtained.

  14. How to Feed the Mammalian Gut Microbiota: Bacterial and Metabolic Modulation by Dietary Fibers

    Directory of Open Access Journals (Sweden)

    Chiara Ferrario

    2017-09-01

    Full Text Available The composition of the gut microbiota of mammals is greatly influenced by diet. Therefore, evaluation of different food ingredients that may promote changes in the gut microbiota composition is an attractive approach to treat microbiota disturbances. In this study, three dietary fibers, such as inulin (I, 10%, resistant starch (RS, 10%, and citrus pectin (3%, were employed as supplements to normal chow diet of adult male rats for 2 weeks. Fecal microbiota composition and corresponding metabolite profiles were assessed before and after prebiotics supplementation. A general increase in the Bacteroidetes phylum was detected with a concurrent reduction in Firmicutes, in particular for I and RS experiments, while additional changes in the microbiota composition were evident at lower taxonomic levels for all the three substrates. Such modifications in the microbiota composition were correlated with changes in metabolic profiles of animals, in particular changes in acetate and succinate levels. This study represents a first attempt to modulate selectively the abundance and/or metabolic activity of various members of the gut microbiota by means of dietary fiber.

  15. Dynamic single-interface hollow fiber liquid phase microextraction of Cr(VI) using ionic liquid containing supported liquid membrane.

    Science.gov (United States)

    Pimparu, Rungaroon; Nitiyanontakit, Sira; Miró, Manuel; Varanusupakul, Pakorn

    2016-12-01

    The concept of dynamic single-interface hollow fiber membrane liquid-phase microextraction (HF-LPME), where the target analyte was extracted on-line and eluted inside the lumen of the HF membrane, was explored. An ionic liquid containing supported liquid membrane was used for the trace determination of Cr(VI) as a model compound. Since the extraction took place on-line inside the hollow fiber membrane, the mass transfer behavior was described and discussed in comparison with the conventional HF-LPME. The extraction efficiency was improved by a recirculation configuration of the sample solution at relatively high sampling flow rates as a result of the increased effective contact area. The positive pressure observed to be built up during extraction was overcome by a flow-balancing pressure design. The dynamic single-interface HF-LPME method with an enrichment factor of 41, a detection limit of 1.2µgL(-1) and determination limit of 4.0µgL(-1) was successfully applied to the reliable determination of Cr(VI) from environmental water samples. The quantification limit is below the maximum contaminant level in drinking water, set at 10µgL(-1) of hexavalent chromium by the California Environmental Protection Agency.

  16. A novel multi-stage direct contact membrane distillation module: Design, experimental and theoretical approaches.

    Science.gov (United States)

    Lee, Jung-Gil; Kim, Woo-Seung; Choi, June-Seok; Ghaffour, Noreddine; Kim, Young-Deuk

    2016-12-15

    An economic desalination system with a small scale and footprint for remote areas, which have a limited and inadequate water supply, insufficient water treatment and low infrastructure, is strongly demanded in the desalination markets. Here, a direct contact membrane distillation (DCMD) process has the simplest configuration and potentially the highest permeate flux among all of the possible MD processes. This process can also be easily instituted in a multi-stage manner for enhanced compactness, productivity, versatility and cost-effectiveness. In this study, an innovative, multi-stage, DCMD module under countercurrent-flow configuration is first designed and then investigate both theoretically and experimentally to identify its feasibility and operability for desalination application. Model predictions and measured data for mean permeate flux are compared and shown to be in good agreement. The effect of the number of module stages on the mean permeate flux, performance ratio and daily water production of the MDCMD system has been theoretically identified at inlet feed and permeate flow rates of 1.5 l/min and inlet feed and permeate temperatures of 70 °C and 25 °C, respectively. The daily water production of a three-stage DCMD module with a membrane area of 0.01 m(2) at each stage is found to be 21.5 kg. Copyright © 2016 Elsevier Ltd. All rights reserved.

  17. A novel multi-stage direct contact membrane distillation module: Design, experimental and theoretical approaches

    KAUST Repository

    Lee, Jung Gil

    2016-10-24

    An economic desalination system with a small scale and footprint for remote areas, which have a limited and inadequate water supply, insufficient water treatment and low infrastructure, is strongly demanded in the desalination markets. Here, a direct contact membrane distillation (DCMD) process has the simplest configuration and potentially the highest permeate flux among all of the possible MD processes. This process can also be easily instituted in a multi-stage manner for enhanced compactness, productivity, versatility and cost-effectiveness. In this study, an innovative, multi-stage, DCMD module under countercurrent-flow configuration is first designed and then investigate both theoretically and experimentally to identify its feasibility and operability for desalination application. Model predictions and measured data for mean permeate flux are compared and shown to be in good agreement. The effect of the number of module stages on the mean permeate flux, performance ratio and daily water production of the MDCMD system has been theoretically identified at inlet feed and permeate flow rates of 1.5 l/min and inlet feed and permeate temperatures of 70 °C and 25 °C, respectively. The daily water production of a three-stage DCMD module with a membrane area of 0.01 m2 at each stage is found to be 21.5 kg.

  18. Carbon Nanotube/Alumina/Polyethersulfone Hybrid Hollow Fiber Membranes with Enhanced Mechanical and Anti-Fouling Properties

    Directory of Open Access Journals (Sweden)

    Yi Feng

    2015-08-01

    Full Text Available Carbon nanotubes (CNTs were incorporated into alumina/polyethersulfone hollow fibre membranes to enhance the mechanical property and the efficiency of water treatment. Results show that the incorporation of CNTs can greatly limit the formation of large surface pores, decrease the void size in support layers and improve the porosity and pore connectivity of alumina/polyethersulfone membranes. As a result of such morphology change and pore size change, both improved flux and rejection were achieved in such CNTs/alumina/polyethersulfone membranes. Moreover, the CNTs/alumina/PES membranes show higher antifouling ability and the flux recoveries after being fouled by bovine serum albumin (BSA and humic acid were improved by 84.1% and 53.2% compared to the samples without CNT incorporation. Besides the improvement in water treatment performance, the incorporation of CNTs enhanced the tensile properties of inorganic/polymer membranes. Therefore, such CNTs/alumina/PES hollow fiber membranes are very promising candidates for good filter media in industry, considering their high efficiency and high mechanical properties.

  19. Gypsum (CaSO42H2O) scaling on polybenzimidazole and cellulose acetate hollow fiber membranes under forward osmosis

    KAUST Repository

    Chen, Si Cong

    2013-11-08

    We have examined the gypsum (CaSO42H2O) scaling phenomena on membranes with different physicochemical properties in forward osmosis (FO) processes. Three hollow fiber membranes made of (1) cellulose acetate (CA), (2) polybenzimidazole (PBI)/polyethersulfone (PES) and (3) PBI-polyhedral oligomeric silsesquioxane (POSS)/polyacrylonitrile (PAN) were studied. For the first time in FO processes, we have found that surface ionic interactions dominate gypsum scaling on the membrane surface. A 70% flux reduction was observed on negatively charged CA and PBI membrane surfaces, due to strong attractive forces. The PBI membrane surface also showed a slightly positive charge at a low pH value of 3 and exhibited a 30% flux reduction. The atomic force microscopy (AFM) force measurements confirmed a strong repulsive force between gypsum and PBI at a pH value of 3. The newly developed PBI-POSS/PAN membrane had ridge morphology and a contact angle of 51.42 14.85 after the addition of hydrophilic POSS nanoparticles and 3 min thermal treatment at 95 C. Minimal scaling and an only 1.3% flux reduction were observed at a pH value of 3. Such a ridge structure may reduce scaling by not providing a locally flat surface to the crystallite at a pH value of 3; thus, gypsum would be easily washed away from the surface. 2013 by the authors; licensee MDPI, Basel, Switzerland.

  20. Carbon Nanotube/Alumina/Polyethersulfone Hybrid Hollow Fiber Membranes with Enhanced Mechanical and Anti-Fouling Properties.

    Science.gov (United States)

    Feng, Yi; Wang, Kun; Davies, Chris H J; Wang, Huanting

    2015-08-20

    Carbon nanotubes (CNTs) were incorporated into alumina/polyethersulfone hollow fibre membranes to enhance the mechanical property and the efficiency of water treatment. Results show that the incorporation of CNTs can greatly limit the formation of large surface pores, decrease the void size in support layers and improve the porosity and pore connectivity of alumina/polyethersulfone membranes. As a result of such morphology change and pore size change, both improved flux and rejection were achieved in such CNTs/alumina/polyethersulfone membranes. Moreover, the CNTs/alumina/PES membranes show higher antifouling ability and the flux recoveries after being fouled by bovine serum albumin (BSA) and humic acid were improved by 84.1% and 53.2% compared to the samples without CNT incorporation. Besides the improvement in water treatment performance, the incorporation of CNTs enhanced the tensile properties of inorganic/polymer membranes. Therefore, such CNTs/alumina/PES hollow fiber membranes are very promising candidates for good filter media in industry, considering their high efficiency and high mechanical properties.

  1. Fiber-optical sensor with miniaturized probe head and nanometer accuracy based on spatially modulated low-coherence interferogram analysis.

    Science.gov (United States)

    Depiereux, Frank; Lehmann, Peter; Pfeifer, Tilo; Schmitt, Robert

    2007-06-10

    Fiber-optical sensors have some crucial advantages compared with rigid optical systems. They allow miniaturization and flexibility of system setups. Nevertheless, optical principles such as low-coherence interferometry can be realized by use of fiber optics. We developed and realized an approach for a fiber-optical sensor, which is based on the analysis of spatially modulated low-coherence interferograms. The system presented consists of three units, a miniaturized sensing probe, a broadband fiber-coupled light source, and an adapted Michelson interferometer, which is used as an optical receiver. Furthermore, the signal processing procedure, which was developed for the interferogram analysis in order to achieve nanometer measurement accuracy, is discussed. A system prototype has been validated thoroughly in different experiments. The results approve the accuracy of the sensor.

  2. Broad and tunable multiwavelength fiber laser at the assistance of modulation-instability-assisted four-wave mixing

    Science.gov (United States)

    Liu, X. M.

    2010-04-01

    Based on a piece of highly-nonlinear near-zero-dispersion-flattened photonic crystal fiber (PCF), a broadly tunable multiwavelength erbium-doped fiber laser is proposed by using a bi-directionally pumping scheme. This kind of PCF induces the modulation-instability-assisted four-wave mixing to generate new wavelengths. The proposed laser with excellent stability is tunable and switchable by adjusting the fiber Bragg gratings and the variable optical attenuators. The outstanding merits of the proposed multiwavelength laser are the flexible tuning and the ultrabroad spectral range over 150 nm. Especially, the proposed laser source can work at the wavelength of less than 1460 nm, overcoming the limit of gain bandwidth of erbium-doped fiber.

  3. Development and modulation of intrinsic membrane properties control the temporal precision of auditory brain stem neurons.

    Science.gov (United States)

    Franzen, Delwen L; Gleiss, Sarah A; Berger, Christina; Kümpfbeck, Franziska S; Ammer, Julian J; Felmy, Felix

    2015-01-15

    Passive and active membrane properties determine the voltage responses of neurons. Within the auditory brain stem, refinements in these intrinsic properties during late postnatal development usually generate short integration times and precise action-potential generation. This developmentally acquired temporal precision is crucial for auditory signal processing. How the interactions of these intrinsic properties develop in concert to enable auditory neurons to transfer information with high temporal precision has not yet been elucidated in detail. Here, we show how the developmental interaction of intrinsic membrane parameters generates high firing precision. We performed in vitro recordings from neurons of postnatal days 9-28 in the ventral nucleus of the lateral lemniscus of Mongolian gerbils, an auditory brain stem structure that converts excitatory to inhibitory information with high temporal precision. During this developmental period, the input resistance and capacitance decrease, and action potentials acquire faster kinetics and enhanced precision. Depending on the stimulation time course, the input resistance and capacitance contribute differentially to action-potential thresholds. The decrease in input resistance, however, is sufficient to explain the enhanced action-potential precision. Alterations in passive membrane properties also interact with a developmental change in potassium currents to generate the emergence of the mature firing pattern, characteristic of coincidence-detector neurons. Cholinergic receptor-mediated depolarizations further modulate this intrinsic excitability profile by eliciting changes in the threshold and firing pattern, irrespective of the developmental stage. Thus our findings reveal how intrinsic membrane properties interact developmentally to promote temporally precise information processing.

  4. Controlled Modulation of Lipid Bilayer State by a Photosensitive Membrane Effector

    DEFF Research Database (Denmark)

    Shen, Chen; Jørgensen, Lars; Zargarani, Dordaneh;

    2015-01-01

    The lipid membrane matrix represents a 2-D liquid-crystal, the properties of which, at fixed other conditions, are locally modulated by the presence of effectors as e.g. cholesterol (passive) or proteins (passive and active). Not only does the incorporation of effectors into the host matrix locally...... by a combination of spectroscopic (UV-vis, NMR, mass spectroscopy), thermodynamic (Langmuir compression, calorimetry) and structural studies (X-ray/neutron reflectometry, grazing incidence X-ray diffraction). The conformational change of the guest upon illumination is coupled into the host system, inducing...... as a response to the conformational switching of the guest effector via external light illumination. In a more general context, similar behavior may be found upon the conformational changes of membrane proteins during work....

  5. Hollow fiber membrane modification with functional zwitterionic macromolecules for improved thromboresistance in artificial lungs.

    Science.gov (United States)

    Ye, Sang-Ho; Arazawa, David T; Zhu, Yang; Shankarraman, Venkat; Malkin, Alexander D; Kimmel, Jeremy D; Gamble, Lara J; Ishihara, Kazuhiko; Federspiel, William J; Wagner, William R

    2015-03-03

    Respiratory assist devices seek optimized performance in terms of gas transfer efficiency and thromboresistance to minimize device size and reduce complications associated with inadequate blood biocompatibility. The exchange of gas with blood occurs at the surface of the hollow fiber membranes (HFMs) used in these devices. In this study, three zwitterionic macromolecules were attached to HFM surfaces to putatively improve thromboresistance: (1) carboxyl-functionalized zwitterionic phosphorylcholine (PC) and (2) sulfobetaine (SB) macromolecules (mPC or mSB-COOH) prepared by a simple thiol-ene radical polymerization and (3) a low-molecular weight sulfobetaine (SB)-co-methacrylic acid (MA) block copolymer (SBMAb-COOH) prepared by reversible addition-fragmentation chain transfer (RAFT) polymerization. Each macromolecule type was covalently immobilized on an aminated commercial HFM (Celg-A) by a condensation reaction, and HFM surface composition changes were analyzed by X-ray photoelectron spectroscopy. Thrombotic deposition on the HFMs was investigated after contact with ovine blood in vitro. The removal of CO2 by the HFMs was also evaluated using a model respiratory assistance device. The HFMs conjugated with zwitterionic macromolecules (Celg-mPC, Celg-mSB, and Celg-SBMAb) showed expected increases in phosphorus or sulfur surface content. Celg-mPC and Celg-SBMAb experienced rates of platelet deposition significantly lower than those of unmodified (Celg-A, >95% reduction) and heparin-coated (>88% reduction) control HFMs. Smaller reductions were seen with Celg-mSB. The CO2 removal rate for Celg-SBMAb HFMs remained comparable to that of Celg-A. In contrast, the rate of removal of CO2 for heparin-coated HFMs was significantly reduced. The results demonstrate a promising approach to modifying HFMs using zwitterionic macromolecules for artificial lung devices with improved thromboresistance without degradation of gas transfer.

  6. Fiber-optic tunable multiwavelength variable attenuator and routing module designs that use bulk acousto-optics.

    Science.gov (United States)

    Riza, Nabeel A; Mughal, M Junaid

    2005-02-10

    A compact fiber-coupled bulk acousto-optical multiwavelength variable optical attenuator module design that uses a retroreflective double-pass geometry within a single bulk acousto-optic tunable filter device is presented. The proposed attenuator module demonstrates a high 17-dB notch dynamic range at a low 100-mW drive power and uses a single bulk collinear-interaction acousto-optic tunable-filter device. Experiments show a low (design is extended to allow for efficient architectures for routing modules such as agile drop filters, analog hitless tap filters, and digital add-drop switches.

  7. Analytical treatment for the study of an erbium-doped fiber ring laser fed by a sinusoidally modulated pump power

    Science.gov (United States)

    Sola, I. J.; Martín, J. C.; Álvarez, J. M.

    2006-02-01

    An analytical procedure is employed to account for the response of an erbium-doped fiber ring laser whose pump power is sinusoidally modulated. The approximations considered, only strictly valid for very low modulation indexes (of the order of some hundredths), reveal the origin of some relationships between resonances of the main harmonics present in the laser response. However, both experimental and numerical results show how qualitative conclusions concerning relationships between harmonics are also valid for modulation indexes much higher than the ones corresponding to the approximation validity range.

  8. Effect of complex optical field on the modulation instability of 100 km unrepeated fiber transmission system with DFRA

    Science.gov (United States)

    Yang, Yangyang; Xu, Pan; Hu, Zhengliang; Hu, Yongming

    2016-10-01

    With the development of networking technology and optical fiber sensor network technology, the use of optical fiber system to construct a large-scale, long distance optical fiber sensing network has become a hotspot of research. Optimizing the system to reach very long sensing ranges actually requires launching high pump and probe powers into the sensing fiber to provide a sufficient signal-to-noise ratio (SNR) on the measurements at the far end of the fiber. However, increasing the input power above a critical level excites undesired nonlinear effects such as the modulation instability (MI) and the stimulated Raman scattering (SRS), which deplete the pump and reduce the maximum sensing range of the system. Compared to SRS, MI shows a lower critical power and thus determines the maximum sensing range of a fiber sensor, so MI becomes the most important factor to limit the sensing range. In order to understand the MI in the system with the DFRA, we design a lot of experiments to test which factors will affect it in the system with distributed fiber Raman amplifier (DFRA) in this paper. From the threshold expression of MI and a lot of experiments, we found that the input power, the state of polarization, the phase and so on, have a significant impact on the system. According to the result of the experiments, we can find the Raman gain affects the MI and find some useful information for suppressing the MI in the later.

  9. Experimental evaluation of a digitized fiber-wireless system employing sigma delta modulation.

    Science.gov (United States)

    Pessoa, Luis M; Coelho, Diogo; Salgado, Henrique M

    2014-07-14

    Digitized radio-over-fiber (D-RoF) transport schemes are being pointed as viable alternative solutions to their analog counterparts, in order to avoid distortion/dynamic range problems. Here we propose a novel D-RoF architecture that takes advantage of a bandpass sigma-delta modulator at the transmitter which subsequently permits the usage of a simpler/cheaper base station that avoids the employment of a digital to analog converter. The proposed architecture exploits the properties of the digital signal to enable the extraction of an higher carrier frequency through the employment of a bandpass filter. Furthermore, we present a comprehensive analysis regarding the impact of a low-cost electro-optic modulation on the quality of received demodulated signal. Finally, a comparison performance analysis between the conventional D-RoF and the proposed architecture is presented. We conclude that although the proposed architecture performs similarly to conventional D-RoF schemes, it is more competitive for either upgrading installed systems as well as for new deployments.

  10. Fiber Bragg grating-based wavelength modulation spectroscopy technique for trace gas sensing

    Science.gov (United States)

    Tiwari, Shivani; Vasa, Nilesh J.; Srinivasan, Balaji

    2016-04-01

    A novel gas sensing system based on a tunable fiber Bragg grating (FBG) and a Super luminescent light emitting diode (SLED) source is proposed for trace gas sensing. Such a system has been demonstrated for precise detection of acetylene (C2H2) using wavelength modulation spectroscopy technique (WMS) based on modulating the Bragg wavelength of FBG within the width of an absorption line of a target gas. The sensing system has been calibrated against specific gas concentrations (ppm) through controlled experiments and the minimum detectable acetylene (C2H2) gas concentration is experimentally found to be 80 ppm (0.008% by volume). Furthermore, the detection limit of the system is estimated to be limited by the noise floor of our system at 7 ppm (0.0007% by volume). The proposed system provides a relatively inexpensive alternative for trace gas sensing based on a well-established FBG technology. Moreover, the proposed system has tremendous potential for simultaneous detection of multiple species through the use of a cascaded set of carefully chosen FBGs.

  11. Controlled Modulation of Lipid Bilayer State by a Photosensitive Membrane Effector

    DEFF Research Database (Denmark)

    Shen, Chen; Jørgensen, Lars; Zargarani, Dordaneh;

    The lipid membrane matrix represents a 2-D liquid-crystal, the properties of which, at fixed other conditions, are locally modulated by the presence of effectors as e.g. cholesterol (passive) or proteins (passive and active). Not only does the incorporation of effectors into the host matrix locally...... by a combination of spectroscopic (UV-vis, NMR, mass spectroscopy), thermodynamic (Langmuir compression, calorimetry) and structural studies (X-ray/neutron reflectometry, grazing incidence X-ray diffraction). The conformational change of the guest upon illumination is coupled into the host system, inducing...

  12. Modulation of Breast Cancer Cell Functions by Intracellular Signaling Through the Membrane Type-1 Matrix Metalloproteinase

    Science.gov (United States)

    2002-10-01

    acts as a membrane binding site for MMP-2.TIMP-2 complex (Fig. 1). Binding of the enzyme -inhibitor complex to MTI-NIMP is required for MMP-2...expressed but not in cells that did not express MT1- MNP (Fig. 7). Fig. 7. MT1-MMP Tet-Off MCF- 7 Scells grown for 24 h in thepresence -..... +.. or in the...tion of uPAR-bound uPA. Because both uPA and MT l- MNP have been implicated in cell migration, it is tempting to speculate that the opposing modulation

  13. A controlled wet-spinning and dip-coating process for preparation of high-permeable TiO2 hollow fiber membranes.

    Science.gov (United States)

    Zhang, Qi; Wang, Hua; Fan, Xinfei; Chen, Shuo; Yu, Hongtao; Quan, Xie

    2016-01-01

    In order to improve the permeate flux of photocatalytic membranes, we present an approach for coupling TiO2 with ceramic hollow fiber membranes. The ceramic hollow fiber membranes with high permeate flux were fabricated by a controlled wet-spinning process using polyethersulfone (PESf) and ceramic powder as precursors and 1-methyl-2-pyrrolidinone as solvent, and the subsequent TiO2 coating was performed by a dip-coating process using tetra-n-butyl titanate as precursor. It has been found that the PESf/ceramic powder ratio could influence the structure of the membranes. Here the as-prepared TiO2 hollow fiber membranes had a pure water flux of 4,450 L/(m(2)·h). The performance of the TiO2 hollow fiber membrane was evaluated using humic acid (HA) as a test substance. The results demonstrated that this membrane exhibited a higher permeate flux under UV irradiation than in the dark and the HA removal efficiency was enhanced. The approach described here provides an operable route to the development of high-permeable photocatalytic membranes for water treatment.

  14. Experimental investigation of PAM, CAP and DMT modulations efficiency over a double-step-index polymer optical fiber

    Science.gov (United States)

    Stepniak, G.; Siuzdak, J.

    2014-08-01

    Investigated was the transmission over step index POF that is 50 m/100 m long with a red DVD laser as a source and a Si p-i-n commercial photo-detector. The maximum bit rates of three modulation formats: PAM, CAP and DMT were sought. Their constellation sizes and symbol rates were varied in order to maximize FEC limited throughputs for each modulation whereas the laser operating point and relevant optical powers were maintained constant for all the modulations. The maximum throughputs were similar for PAM and CAP, namely 3.3/2 Gbit/s for PAM, and 3.15/2.1 for CAP for 50/100 m fiber, respectively. The bit rates for DMT were 2.65/1.65 Gbit/s for the respective lengths of the fiber. We attribute the inferior performance of DMT to its high value of peak to average power ratio.

  15. Application of nano TiO2 modified hollow fiber membranes in algal membrane bioreactors for high-density algae cultivation and wastewater polishing.

    Science.gov (United States)

    Hu, Weiming; Yin, Jun; Deng, Baolin; Hu, Zhiqiang

    2015-10-01

    Polyvinylidene fluoride (PVDF) hollow fiber membranes with nano-TiO2 (5% of PVDF by mass, average size = 25 nm) additives were fabricated and applied for high-density algae (Chlorella vulgaris) cultivation. At the average light intensity of 121 μmol/m(2)/s, the algal membrane bioreactors (A-MBR) operated at a hydraulic retention time of 0.5d and an average solids retention time of 25d had an average algae biomass concentration of 2350 ± 74 mg/L (in COD units) and algal biomass production rate of 6.5 ± 0.1g/m(2)/d. The A-MBRs removed an average of 78% of phosphorus from the wastewater at the initial total phosphorus concentrations ranging from 3.5 to 8.6 mg/L. The nano TiO2-embedded membranes had improved surface hydrophilicity with its total resistance about 50% lower than that of the control. This study demonstrated that PVDF/TiO2 nanocomposite membranes had a better antifouling property for high-density algae cultivation and wastewater polishing. Copyright © 2015 Elsevier Ltd. All rights reserved.

  16. Active Q-switching of a fiber laser using a modulated fiber Fabry-Perot filter and a fiber Bragg grating

    Science.gov (United States)

    Martínez Manuel, Rodolfo; Kaboko, J. J. M.; Shlyagin, M. G.

    2016-02-01

    We propose and demonstrate a simple and robust actively Q-switched erbium-doped fiber ring cavity laser. The Q-switching is based on dynamic spectral overlapping of two filters, namely a fiber Bragg grating-based filter and a fiber Fabry-Perot tunable filter. Using 3.5 m of erbium-doped fiber and a pump power of only 60 mW, Q-switched pulses with a peak power of 9.7 W and a pulse duration of 500 ns were obtained. A pulse repetition rate can be continuously varied from a single shot to a few KHz.

  17. Membrane voltage modulates the GABA(A) receptor gating in cultured rat hippocampal neurons.

    Science.gov (United States)

    Pytel, Maria; Mercik, Katarzyna; Mozrzymas, Jerzy W

    2006-02-01

    The kinetics of GABAergic currents in neurons is known to be modulated by the membrane voltage but the underlying mechanisms have not been fully explored. In particular, the impact of membrane potential on the GABA(A) receptor gating has not been elucidated. In the present study, the effect of membrane voltage on current responses elicited by ultrafast GABA applications was studied in cultured hippocampal neurons. The current to voltage relationship (I-V) for responses to saturating [GABA] (10 mM) showed an inward rectification (slope conductance at positive voltages was 0.62 +/- 0.05 of that at negative potentials). On the contrary, I-V for currents evoked by low [GABA] (1 microM) showed an outward rectification. The onset of currents elicited by saturating [GABA] was significantly accelerated at positive potentials. Analysis of currents evoked by prolonged applications of saturating [GABA] revealed that positive voltages significantly increased the rate and extent of desensitization. The onsets of current responses to non-saturating [GABA] were significantly accelerated at positive voltages indicating an enhancement of the binding rate. However, at low [GABA] at which the onset rate is expected to approach an asymptote set by opening/closing and unbinding rates, no significant modification of current onset by voltage was observed. Quantitative analysis based on model simulations indicated that the major effect of membrane depolarization was to increase the rates of binding, desensitization and of opening as well as to slightly reduce the rate of exit from desensitization. In conclusion, we provide evidence that membrane voltage affects the GABA(A) receptor microscopic gating.

  18. Experimental study on the separation of CO{sub 2} from flue gas using hollow fiber membrane contactors without wetting

    Energy Technology Data Exchange (ETDEWEB)

    Yan, Shui-ping; Fang, Meng-Xiang; Zhang, Wei-Feng; Luo, Zhong-Yang; Cen, Ke-Fa [State Key Laboratory of Clean Energy Utilization, Zhejiang University, Hangzhou 310027 (China); Wang, Shu-Yuan; Xu, Zhi-Kang [Institute of Polymer Science, Zhejiang University, Hangzhou 310027 (China)

    2007-05-15

    Experiments on CO{sub 2} removal from flue gas using polypropylene (PP) hollow fiber membrane contactors were conducted in this study. Absorbents including aqueous potassium glycinate (PG) solution, aqueous solutions of monoethanolamine (MEA) and methyldiethanolamine (MDEA) were used to absorb CO{sub 2} in the experiments. Based on the wetting experimental results, aqueous PG solution can offer a higher surface tension than water, aqueous MEA and MDEA solutions. Aqueous PG solution has a lower potential of membrane wetting after a continuously steady operation for 40 h to maintain CO{sub 2} removal efficiency of about 90%. Under moderate operating conditions, effects of the temperature, flow rate, and concentration of absorbents, and the flow rate of flue gas as well as the volumetric concentration of carbon dioxide in the flue gas on the mass transfer rate of CO{sub 2} were studied on a pilot-scale test facility. Unlike conventional absorbents, the mass transfer decreases with an increasing liquid temperature when using aqueous PG solution. Results show that CO{sub 2} removal efficiency was above 90% and the mass transfer rate was above 2.0 mol/(m{sup 2} h) using the PG aqueous solution. It indicates that the hollow fiber membrane contactor has a great potential in the area of CO{sub 2} separation from flue gas when absorbent's concentration and liquid-gas pressure difference are designed elaborately. (author)

  19. Modulation of Wound Healing and Scar Formation by MG53 Protein-mediated Cell Membrane Repair*

    Science.gov (United States)

    Li, Haichang; Duann, Pu; Lin, Pei-Hui; Zhao, Li; Fan, Zhaobo; Tan, Tao; Zhou, Xinyu; Sun, Mingzhai; Fu, Minghuan; Orange, Matthew; Sermersheim, Matthew; Ma, Hanley; He, Duofen; Steinberg, Steven M.; Higgins, Robert; Zhu, Hua; John, Elizabeth; Zeng, Chunyu; Guan, Jianjun; Ma, Jianjie

    2015-01-01

    Cell membrane repair is an important aspect of physiology, and disruption of this process can result in pathophysiology in a number of different tissues, including wound healing, chronic ulcer and scarring. We have previously identified a novel tripartite motif family protein, MG53, as an essential component of the cell membrane repair machinery. Here we report the functional role of MG53 in the modulation of wound healing and scarring. Although MG53 is absent from keratinocytes and fibroblasts, remarkable defects in skin architecture and collagen overproduction are observed in mg53−/− mice, and these animals display delayed wound healing and abnormal scarring. Recombinant human MG53 (rhMG53) protein, encapsulated in a hydrogel formulation, facilitates wound healing and prevents scarring in rodent models of dermal injuries. An in vitro study shows that rhMG53 protects against acute injury to keratinocytes and facilitates the migration of fibroblasts in response to scratch wounding. During fibrotic remodeling, rhMG53 interferes with TGF-β-dependent activation of myofibroblast differentiation. The resulting down-regulation of α smooth muscle actin and extracellular matrix proteins contributes to reduced scarring. Overall, these studies establish a trifunctional role for MG53 as a facilitator of rapid injury repair, a mediator of cell migration, and a modulator of myofibroblast differentiation during wound healing. Targeting the functional interaction between MG53 and TGF-β signaling may present a potentially effective means for promoting scarless wound healing. PMID:26306047

  20. Optical phase-modulated radio-over-fiber links with k-means algorithm for digital demodulation of 8PSK subcarrier multiplexed signals

    DEFF Research Database (Denmark)

    Guerrero Gonzalez, Neil; Zibar, Darko; Yu, Xianbin

    2010-01-01

    A k-means algorithm for phase recovery of three, 50 Mbaud, 8PSK subcarrier multiplexed signals at 5 GHz for optical phase-modulated radio-over-fiber is proposed and experimentally demonstrated after 40 km of single mode fiber transmission......A k-means algorithm for phase recovery of three, 50 Mbaud, 8PSK subcarrier multiplexed signals at 5 GHz for optical phase-modulated radio-over-fiber is proposed and experimentally demonstrated after 40 km of single mode fiber transmission...

  1. Rate-adaptive modulation and coding for optical fiber transmission systems

    Science.gov (United States)

    Gho, Gwang-Hyun; Kahn, Joseph M.

    2011-01-01

    Rate-adaptive optical transmission techniques adjust information bit rate based on transmission distance and other factors affecting signal quality. These techniques enable increased bit rates over shorter links, while enabling transmission over longer links when regeneration is not available. They are likely to become more important with increasing network traffic and a continuing evolution toward optically switched mesh networks, which make signal quality more variable. We propose a rate-adaptive scheme using variable-rate forward error correction (FEC) codes and variable constellations with a fixed symbol rate, quantifying how achievable bit rates vary with distance. The scheme uses serially concatenated Reed-Solomon codes and an inner repetition code to vary the code rate, combined with singlecarrier polarization-multiplexed M-ary quadrature amplitude modulation (PM-M-QAM) with variable M and digital coherent detection. A rate adaptation algorithm uses the signal-to-noise ratio (SNR) or the FEC decoder input bit-error ratio (BER) estimated by a receiver to determine the FEC code rate and constellation size that maximizes the information bit rate while satisfying a target FEC decoder output BER and an SNR margin, yielding a peak rate of 200 Gbit/s in a nominal 50-GHz channel bandwidth. We simulate single-channel transmission through a long-haul fiber system incorporating numerous optical switches, evaluating the impact of fiber nonlinearity and bandwidth narrowing. With zero SNR margin, we achieve bit rates of 200/100/50 Gbit/s over distances of 650/2000/3000 km. Compared to an ideal coding scheme, the proposed scheme exhibits a performance gap ranging from about 6.4 dB at 650 km to 7.5 dB at 5000 km.

  2. Preparation and properties of hexagonal boron nitride fibers used as high temperature membrane filter

    Energy Technology Data Exchange (ETDEWEB)

    Hou, Xinmei, E-mail: houxinmei@ustb.edu.cn; Yu, Ziyou; Li, Yang; Chou, Kuo-Chih

    2014-01-01

    Graphical abstract: - Highlights: • h-BN fibers were successfully fabricated using H{sub 3}BO{sub 3} and C{sub 3}H{sub 6}N{sub 6} as raw materials. • The obtained BN fibers were polycrystalline and uniform in morphology. • It exhibited good oxidation resistance and low thermal expansion coefficient. - Abstract: Hexagonal boron nitride fibers were synthesized via polymeric precursor method using boric acid (H{sub 3}BO{sub 3}) and melamine (C{sub 3}H{sub 6}N{sub 6}) as raw materials. The precursor fibers were synthesized by water bath and BN fibers were prepared from the precursor at 1873 K for 3 h in flowing nitrogen atmosphere. The crystalline phase and microstructures of BN fibers were examined by X-ray diffraction, field emission scanning electron microscopy, transmission electron microscopy and high resolution electron microscopy. The results showed that h-BN fibers with uniform morphology were successfully fabricated. The well-synthesized BN fibers were polycrystalline with 0.4–1.5 μm in diameter and 200–500 μm in length. The as-prepared samples exhibited good oxidation resistance and low thermal expansion coefficient at high temperature.

  3. Optical-fiber-coupled inferometric measurement of tympanic membrane temperature: a new diagnostic tool for acute otitis media

    Science.gov (United States)

    DeRowe, Ari; Ophir, Eyal; Sade, Sharon; Fishman, Gadi; Ophir, Dov; Grankin, Mila; Katzir, Abraham

    1998-07-01

    A novel infrared (IR) transparent optical fiber coupled to a hand held otoscope and a radiometer was constructed and used to measure the temperatures of the tympanic membrane (TM) and to distinguish between diseased and healthy middle ears. A greater temperature difference between TM readings was found when Acute Otitis Media (AOM) existed in one of the ears examined. This supports the hypothesis that acute inflammation of the middle ear will result in elevated local temperature when measured in such a way that the reading is taken only from the TM without interference of the external canal. The use of an optical fiber enabled temperature measurements of the TM with high spatial resolution eliminating the external ear canal interference. A small patient population was examined and the initial results were statistically significant. In the hands of the primary care physician, this tool would prevent misdiagnosis of AOM preventing indiscriminate use of antibiotics and avoiding complications by early diagnosis.

  4. THE ROLE OF POROUS MEDIA IN MODELING FLUID FLOW WITHIN HOLLOW FIBER MEMBRANES OF THE TOTAL ARTIFICIAL LUNG.

    Science.gov (United States)

    Khanafer, Khalil; Cook, Keith; Marafie, Alia

    2012-01-01

    A numerical study was conducted to analyze fluid flow within hollow fiber membranes of the artificial lungs. The hollow fiber bundle was approximated using a porous media model. In addition, the transport equations were solved using the finite-element formulation based on the Galerkin method of weighted residuals. Comparisons with previously published work on the basis of special cases were performed and found to be in excellent agreement. A Newtonian viscous fluid model for the blood was used. Different flow models for porous media, such as the Brinkman-extended Darcy model, Darcy's law model, and the generalized flow model, were considered. Results were obtained in terms of streamlines, velocity vectors, and pressure distribution for various Reynolds numbers and Darcy numbers. The results from this investigation showed that the pressure drop across the artificial lung device increased with an increase in the Reynolds number. In addition, the pressure drop was found to increase significantly for small Darcy numbers.

  5. Electric field modulation of the membrane potential in solid-state ion channels.

    Science.gov (United States)

    Guan, Weihua; Reed, Mark A

    2012-12-12

    Biological ion channels are molecular devices that allow a rapid flow of ions across the cell membrane. Normal physiological functions, such as generating action potentials for cell-to-cell communication, are highly dependent on ion channels that can open and close in response to external stimuli for regulating ion permeation. Mimicking these biological functions using synthetic structures is a rapidly progressing yet challenging area. Here we report the electric field modulation of the membrane potential phenomena in mechanically and chemically robust solid-state ion channels, an abiotic analogue to the voltage-gated ion channels in living systems. To understand the complex physicochemical processes in the electric field regulated membrane potential behavior, both quasi-static and transient characteristics of converting transmembrane ion gradients into electric potential are investigated. It is found that the transmembrane potential can be adequately tuned by an external electrical stimulation, thanks to the unique properties of the voltage-regulated selective ion transport through a nanoscale channel.

  6. Evidence that some membrane ligands modulate the plasmalemma fluidity of endothelial cells in culture.

    Science.gov (United States)

    Jinga, V V; Badea, M G; Hörer, O

    1986-01-01

    The effect of some membrane ligands on the plasmalemmal fluidity of endothelial cells from bovine aorta in culture was investigated. The ligands used were: cationic ferritin (pI 8.5), soybean agglutinin, concanavalin A, wheat germ agglutinin, as well as glutaraldehyde at different concentrations. The fluidity probe employed was 1,6-diphenyl-1, 3, 5-hexatriene (DPH) and the parameter determined to quantify the fluidity was fluorescence steady-state anisotropy. The optimum time interval required by the insertion of the fluorescent probe in plasmalemma and the appropriate density of cells in the sample were determined. Rigidisation of plasmalemma was detected following its interaction with glutaraldehyde at concentrations ranging from 0.5% to 2% (+8% to +14% relative to the controls). After exposing endothelial cells to wheat germ agglutinin, concanavalin A and cationic ferritin pI 8.5, no modifications in the steady-state DPH fluorescence anisotropy were noticed. However, plasmalemmal rigidisation of +10% to +14% relative to the controls was obtained when endothelial cells were treated with 1 mg/ml and 2 mg/ml of soybean agglutinin, respectively. The possible mechanism of membrane fluidity modulation by membrane ligands and the usefulness of such investigations are discussed.

  7. NlpI-mediated modulation of outer membrane vesicle production through peptidoglycan dynamics in Escherichia coli.

    Science.gov (United States)

    Schwechheimer, Carmen; Rodriguez, Daniel L; Kuehn, Meta J

    2015-06-01

    Outer membrane vesicles (OMVs) are ubiquitously secreted from the outer membrane (OM) of Gram-negative bacteria. These heterogeneous structures are composed of OM filled with periplasmic content from the site of budding. By analyzing mutants that have vesicle production phenotypes, we can gain insight into the mechanism of OMV budding in wild-type cells, which has thus far remained elusive. In this study, we present data demonstrating that the hypervesiculation phenotype of the nlpI deletion mutant of Escherichia coli correlates with changes in peptidoglycan (PG) dynamics. Our data indicate that in stationary phase cultures the nlpI mutant exhibits increased PG synthesis that is dependent on spr, consistent with a model in which NlpI controls the activity of the PG endopeptidase Spr. In log phase, the nlpI mutation was suppressed by a dacB mutation, suggesting that NlpI regulates penicillin-binding protein 4 (PBP4) during exponential growth. The data support a model in which NlpI negatively regulates PBP4 activity during log phase, and Spr activity during stationary phase, and that in the absence of NlpI, the cell survives by increasing PG synthesis. Further, the nlpI mutant exhibited a significant decrease in covalent outer membrane (OM-PG) envelope stabilizing cross-links, consistent with its high level of OMV production. Based on these results, we propose that one mechanism wild-type Gram-negative bacteria can use to modulate vesiculation is by altering PG-OM cross-linking via localized modulation of PG degradation and synthesis. © 2015 The Authors. MicrobiologyOpen published by John Wiley & Sons Ltd.

  8. Development of Nanofiller-Modulated Polymeric Oxygen Enrichment Membranes for Reduction of Nitrogen Oxides in Coal Combustion

    Energy Technology Data Exchange (ETDEWEB)

    Jianzhong Lou; Shamsuddin Ilias

    2010-12-31

    North Carolina A&T State University in Greensboro, North Carolina, has undertaken this project to develop the knowledge and the material to improve the oxygen-enrichment polymer membrane, in order to provide high-grade oxygen-enriched streams for coal combustion and gasification applications. Both experimental and theoretical approaches were used in this project. The membranes evaluated thus far include single-walled carbon nano-tube, nano-fumed silica polydimethylsiloxane (PDMS), and zeolite-modulated polyimide membranes. To document the nanofiller-modulated polymer, molecular dynamics simulations have been conducted to calculate the theoretical oxygen molecular diffusion coefficient and nitrogen molecular coefficient inside single-walled carbon nano-tube PDMS membranes, in order to predict the effect of the nano-tubes on the gas-separation permeability. The team has performed permeation and diffusion experiments using polymers with nano-silica particles, nano-tubes, and zeolites as fillers; studied the influence of nano-fillers on the self diffusion, free volume, glass transition, oxygen diffusion and solubility, and perm-selectivity of oxygen in polymer membranes; developed molecular models of single-walled carbon nano-tube and nano-fumed silica PDMS membranes, and zeolites-modulated polyimide membranes. This project partially supported three graduate students (two finished degrees and one transferred to other institution). This project has resulted in two journal publications and additional publications will be prepared in the near future.

  9. Development of Nanofiller-Modulated Polymeric Oxygen Enrichment Membranes for Reduction of Nitrogen Oxides in Coal Combustion

    Energy Technology Data Exchange (ETDEWEB)

    Jianzhong Lou; Shamsuddin Ilias

    2010-12-31

    North Carolina A&T State University in Greensboro, North Carolina, has undertaken this project to develop the knowledge and the material to improve the oxygen-enrichment polymer membrane, in order to provide high-grade oxygen-enriched streams for coal combustion and gasification applications. Both experimental and theoretical approaches were used in this project. The membranes evaluated thus far include single-walled carbon nano-tube, nano-fumed silica polydimethylsiloxane (PDMS), and zeolite-modulated polyimide membranes. To document the nanofiller-modulated polymer, molecular dynamics simulations have been conducted to calculate the theoretical oxygen molecular diffusion coefficient and nitrogen molecular coefficient inside single-walled carbon nano-tube PDMS membranes, in order to predict the effect of the nano-tubes on the gas-separation permeability. The team has performed permeation and diffusion experiments using polymers with nano-silica particles, nano-tubes, and zeolites as fillers; studied the influence of nano-fillers on the self diffusion, free volume, glass transition, oxygen diffusion and solubility, and perm-selectivity of oxygen in polymer membranes; developed molecular models of single-walled carbon nano-tube and nano-fumed silica PDMS membranes, and zeolites-modulated polyimide membranes. This project partially supported three graduate students (two finished degrees and one transferred to other institution). This project has resulted in two journal publications and additional publications will be prepared in the near future.

  10. Non-linear Membrane Properties in Entorhinal Cortical Stellate Cells Reduce Modulation of Input-Output Responses by Voltage Fluctuations.

    Science.gov (United States)

    Fernandez, Fernando R; Malerba, Paola; White, John A

    2015-04-01

    The presence of voltage fluctuations arising from synaptic activity is a critical component in models of gain control, neuronal output gating, and spike rate coding. The degree to which individual neuronal input-output functions are modulated by voltage fluctuations, however, is not well established across different cortical areas. Additionally, the extent and mechanisms of input-output modulation through fluctuations have been explored largely in simplified models of spike generation, and with limited consideration for the role of non-linear and voltage-dependent membrane properties. To address these issues, we studied fluctuation-based modulation of input-output responses in medial entorhinal cortical (MEC) stellate cells of rats, which express strong sub-threshold non-linear membrane properties. Using in vitro recordings, dynamic clamp and modeling, we show that the modulation of input-output responses by random voltage fluctuations in stellate cells is significantly limited. In stellate cells, a voltage-dependent increase in membrane resistance at sub-threshold voltages mediated by Na+ conductance activation limits the ability of fluctuations to elicit spikes. Similarly, in exponential leaky integrate-and-fire models using a shallow voltage-dependence for the exponential term that matches stellate cell membrane properties, a low degree of fluctuation-based modulation of input-output responses can be attained. These results demonstrate that fluctuation-based modulation of input-output responses is not a universal feature of neurons and can be significantly limited by subthreshold voltage-gated conductances.

  11. Assessment of Fiber Chromatic Dispersion Based on Elimination of Second-Order Harmonics in Optical OFDM Single Sideband Modulation Using Mach Zehnder Modulator

    Science.gov (United States)

    Patel, Dhananjay; Singh, Vinay Kumar; Dalal, U. D.

    2016-07-01

    This work addresses the analytical and numerical investigations of the transmission performance of an optical Single Sideband (SSB) modulation technique generated by a Mach Zehnder Modulator (MZM) with a 90° and 120° hybrid coupler. It takes into account the problem of chromatic dispersion in single mode fibers in Passive Optical Networks (PON), which severely degrades the performance of the system. Considering the transmission length of the fiber, the SSB modulation generated by maintaining a phase shift of π/2 between the two electrodes of the MZM provides better receiver sensitivity. However, the power of higher-order harmonics generated due to the nonlinearity of the MZM is directly proportional to the modulation index, making the SSB look like a quasi-double sideband (DSB) and causing power fading due to chromatic dispersion. To eliminate one of the second-order harmonics, the SSB signal based on an MZM with a 120° hybrid coupler is simulated. An analytical model of conventional SSB using 90° and 120° hybrid couplers is established. The latter suppresses unwanted (upper/lower) first-order and second-order (lower/upper) sidebands. For the analysis, a varying quadrature amplitude modulation (QAM) Orthogonal Frequency Division Multiplexing (OFDM) signal with a data rate of 5 Gb/s is upconverted using both of the SSB techniques and is transmitted over a distance of 75 km in Single Mode Fiber (SMF). The simulation results show that the SSB with 120° hybrid coupler proves to be more immune to chromatic dispersion as compared to the conventional SSB technique. This is in tandem with the theoretical analysis presented in the article.

  12. Extraction kinetics of phenol with N, N-di (1-methyl-heptyl)acetamide-kerosene using hollow fiber membrane extractor

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    Extraction kinetics of phenol with N, N-di(l-methyl-heptyl) acetamide-kerosene using hollow fiber membrane extractor has been studied. The rate regularities and kinetic types of forward and backward extraction were obtained respectively by determining the forward and backward extraction rate under various experimental conditions. The mass transfer mechanism was discussed. Both the forward and backward extraction of phenol might be controlled by diffusion processes, and the diffusion resistance for both forward and backward extraction mainly exists in aqueous phase. In addition, ways to optimize the extraction process of phenol were discussed as well.

  13. In situ synthesis of lead sulfide nanoclusters on eggshell membrane fibers by an ambient bio-inspired technique

    Science.gov (United States)

    Su, Huilan; Han, Jie; Wang, Na; Dong, Qun; Zhang, Di; Zhang, Chunfu

    2008-02-01

    An ambient aqueous soakage technique is successfully developed to prepare PbS nanoclusters on eggshell membrane (ESM) fibers containing some active functional groups (hydroxyl, amine, imine, etc). Based on the biomaterial ESM serving as the reactive substrate and some ESM biomacromolecules acting as the surfactant, PbS nanocrystallites are in situ formed and further assembled into well-distributed nanoparticle aggregations. This moderate bio-inspired strategy would be of great value in preparing novel functional nanomaterials. The as-prepared hybrid PbS/ESM nanocomposites could have great potential for applications in semiconductor industries, optoelectronic fields, and nanostructured devices.

  14. Modeling and Validation of Performance Limitations for the Optimal Design of Interferometric and Intensity-Modulated Fiber Optic Displacement Sensors

    Energy Technology Data Exchange (ETDEWEB)

    Moro, Erik A. [Los Alamos National Laboratory

    2012-06-07

    Optical fiber sensors offer advantages over traditional electromechanical sensors, making them particularly well-suited for certain measurement applications. Generally speaking, optical fiber sensors respond to a desired measurand through modulation of an optical signal's intensity, phase, or wavelength. Practically, non-contacting fiber optic displacement sensors are limited to intensity-modulated and interferometric (or phase-modulated) methodologies. Intensity-modulated fiber optic displacement sensors relate target displacement to a power measurement. The simplest intensity-modulated sensor architectures are not robust to environmental and hardware fluctuations, since such variability may cause changes in the measured power level that falsely indicate target displacement. Differential intensity-modulated sensors have been implemented, offering robustness to such intensity fluctuations, and the speed of these sensors is limited only by the combined speed of the photodetection hardware and the data acquisition system (kHz-MHz). The primary disadvantages of intensity-modulated sensing are the relatively low accuracy (?m-mm for low-power sensors) and the lack of robustness, which consequently must be designed, often with great difficulty, into the sensor's architecture. White light interferometric displacement sensors, on the other hand, offer increased accuracy and robustness. Unlike their monochromatic-interferometer counterparts, white light interferometric sensors offer absolute, unambiguous displacement measurements over large displacement ranges (cm for low-power, 5 mW, sources), necessitating no initial calibration, and requiring no environmental or feedback control. The primary disadvantage of white light interferometric displacement sensors is that their utility in dynamic testing scenarios is limited, both by hardware bandwidth and by their inherent high-sensitivity to Doppler-effects. The decision of whether to use either an intensity-modulated

  15. Membrane potential-dependent modulation of recurrent inhibition in rat neocortex.

    Directory of Open Access Journals (Sweden)

    Jie Zhu

    2011-03-01

    Full Text Available Dynamic balance of excitation and inhibition is crucial for network stability and cortical processing, but it is unclear how this balance is achieved at different membrane potentials (V(m of cortical neurons, as found during persistent activity or slow V(m oscillation. Here we report that a V(m-dependent modulation of recurrent inhibition between pyramidal cells (PCs contributes to the excitation-inhibition balance. Whole-cell recording from paired layer-5 PCs in rat somatosensory cortical slices revealed that both the slow and the fast disynaptic IPSPs, presumably mediated by low-threshold spiking and fast spiking interneurons, respectively, were modulated by changes in presynaptic V(m. Somatic depolarization (>5 mV of the presynaptic PC substantially increased the amplitude and shortened the onset latency of the slow disynaptic IPSPs in neighboring PCs, leading to a narrowed time window for EPSP integration. A similar increase in the amplitude of the fast disynaptic IPSPs in response to presynaptic depolarization was also observed. Further paired recording from PCs and interneurons revealed that PC depolarization increases EPSP amplitude and thus elevates interneuronal firing and inhibition of neighboring PCs, a reflection of the analog mode of excitatory synaptic transmission between PCs and interneurons. Together, these results revealed an immediate V(m-dependent modulation of cortical inhibition, a key strategy through which the cortex dynamically maintains the balance of excitation and inhibition at different states of cortical activity.

  16. Low-cost bidirectional hybrid fiber-visible laser light communication system based on carrier-less amplitude phase modulation

    Science.gov (United States)

    He, Jing; Dong, Huan; Deng, Rui; Chen, Lin

    2016-08-01

    We propose a bidirectional hybrid fiber-visible laser light communication (fiber-VLC) system. To reduce the cost of the system, the cheap and easy integration red vertical cavity surface emitting lasers, low-complexity carrier-less amplitude phase modulation format, and wavelength reuse technique are utilized. Meanwhile, the automatic gain control amplifier voltage and bias voltage for downlink and uplink are optimized. The simulation results show that, by using the proposed system, the bit error rate of 3.8×10-3 can be achieved for 16-Gbps CAP signal after 30-km standard single mode fiber and 8-m VLC bidirectional transmission. Therefore, it indicates the feasibility and potential of proposed system for indoor access network.

  17. Converged Wireless and Wireline Access System Based on Optical Phase Modulation for Both Radio-Over-Fiber and Baseband Signals

    DEFF Research Database (Denmark)

    Yu, Xianbin; Jensen, Jesper Bevensee; Zibar, Darko

    2008-01-01

    We propose and experimentally investigate a scheme for transmitting a phase-modulated radio-over-fiber (RoF) signal along an existing fiber infrastructure without degradation of the existing baseband signal. Optical phase encoding of both signals, namely a baseband 21.4-Gb/s nonreturn......-to-zero differential quaternary phase-shift keyed signal and a 5.25-GHz RoF carrying 1.25 Gb/s, enables the use of identical optical receiver structures. The experimental results show that both receivers achieve error-free operation after 80-km standard single-mode fiber transmission. The proposed scheme has potential...... applications for converged wireless and wireline optical access networks....

  18. Q-switched mode-locking of an erbium-doped fiber laser using cavity modulation frequency detuning.

    Science.gov (United States)

    Chang, You Min; Lee, Junsu; Jhon, Young Min; Lee, Ju Han

    2012-07-20

    We present the results of an investigation regarding a Q-switched mode-locked fiber laser scheme based on a cavity modulation frequency detuning technique. The approach is based on undamped laser relaxation oscillations occurring due to frequency detuning in the fundamental cavity resonance frequency. Through a range of experiments with an erbium-doped, fiber-based, ring-cavity laser, this approach has been shown to be capable of generating high-quality Q-switched mode-locked pulses from an optical fiber-based laser. The maximum frequency detuning range for a stable Q-switched mode-locking operation has been observed to vary depending on the pump power used. We found that the highest pulse peak power was obtained at the frequency detuning threshold at which the operation changed from the mode-locking to the Q-switched mode-locking regime.

  19. Nonlinear response of a unidirectional erbium-doped fiber ring laser to a sinusoidally modulated pump power

    Science.gov (United States)

    Sola, I. J.; Martín, J. C.; Álvarez, J. M.

    2002-11-01

    The response of a unidirectional erbium-doped fiber ring laser, excited by a sinusoidally modulated pump power, is analyzed both experimentally and theoretically. Experimentally, several resonance peaks are observed, as well as different frequency ranges showing bistable behaviour. Appearance of all resonance peaks obtained can be explained taking into account simple relations between the pump modulation frequency and the system natural frequency. Theoretically, it is shown how a model which combines the theory of erbium-doped fibers and the semiclassical laser treatment can account for all phenomena observed, with good agreement. In particular, it is demonstrated that a correct description of the bistable regions requires taking into account powers and population distributions along the laser active medium.

  20. Fouling behaviors of polybenzimidazole (PBI)-polyhedral oligomeric silsesquioxane (POSS)/polyacrylonitrile (PAN) hollow fiber membranes for engineering osmosis processes

    KAUST Repository

    Chen, Sicong

    2014-02-01

    This paper investigated the individual effects of reverse salt flux and permeate flux on fouling behaviors of as-spun and annealed polybenzimidazole (PBI)-polyhedral oligomeric silsesquioxane (POSS)/polyacrylonitrile (PAN) hollow fiber membranes under forward osmosis (FO) and pressure retarded osmosis (PRO) processes. Two types of membrane fouling had been studied; namely, inorganic fouling (CaSO4·2H2O gypsum scaling) during FO operations and organic fouling (sodium alginate fouling) during PRO operations. It is found that gypsum scaling on the membrane surface may be inhibited and even eliminated with an increase in reverse MgCl2 flux due to competitive formations of MgSO4° and CaSO4·2H2O. In contrast, the increase of reverse NaCl flux exhibits a slight enhancement on alginate fouling in both FO and PRO processes. Comparing to the reverse salt flux, the permeate flux always plays a dominant role in fouling. Therefore, lesser fouling has been observed on the membrane surface under the pressurized PRO process than FO process because the reduced initial flux mitigates the fouling phenomena more significantly than the enhancement caused by an increase in reverse NaCl flux. © 2013 Elsevier B.V.