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Sample records for external limiting membrane

  1. Infrared limit in external field scattering

    CERN Document Server

    Herdegen, Andrzej

    2012-01-01

    Scattering of electrons/positrons by external classical electromagnetic wave packet is considered in infrared limit. In this limit the scattering operator exists and produces physical effects, although the scattering cross-section is trivial.

  2. Dynamic External Hashing: The Limit of Buffering

    CERN Document Server

    Wei, Zhewei; Zhang, Qin

    2008-01-01

    Hash tables are one of the most fundamental data structures in computer science, in both theory and practice. They are especially useful in external memory, where their query performance approaches the ideal cost of just one disk access. Knuth gave an elegant analysis showing that with some simple collision resolution strategies such as linear probing or chaining, the expected average number of disk I/Os of a lookup is merely $1+1/2^{\\Omega(b)}$, where each I/O can read a disk block containing $b$ items. Inserting a new item into the hash table also costs $1+1/2^{\\Omega(b)}$ I/Os, which is again almost the best one can do if the hash table is entirely stored on disk. However, this assumption is unrealistic since any algorithm operating on an external hash table must have some internal memory (at least $\\Omega(1)$ blocks) to work with. The availability of a small internal memory buffer can dramatically reduce the amortized insertion cost to $o(1)$ I/Os for many external memory data structures. In this paper we...

  3. 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.

  4. External and internal limitations in amplitude-modulation processing

    DEFF Research Database (Denmark)

    Ewert, Stephan; Dau, Torsten

    2004-01-01

    Three experiments are presented to explore the relative role of "external" signal variability and "internal" resolution limitations of the auditory system in the detection and discrimination of amplitude modulations (AM). In the first experiment, AM-depth discrimination performance was determined......, 16, 64, and 256 Hz, applied to either a band-limited random-noise carrier or a deterministic ("frozen") noise carrier, as a function of carrier bandwidth (8 to 2048 Hz). In general, detection thresholds were higher for the random- than for the frozen-noise carriers. For both carrier types, thresholds......-filterbank models. The predictions revealed that AM-depth discrimination and AM detection are limited by a combination of the external signal variability and an internal "Weber-fraction" noise process....

  5. Ultraspinning limits and rotating hyperboloid membranes

    Energy Technology Data Exchange (ETDEWEB)

    Hennigar, Robie A., E-mail: rhennigar@uwaterloo.ca [Department of Physics and Astronomy, University of Waterloo, Waterloo, Ontario, N2L 3G1 (Canada); Kubizňák, David, E-mail: dkubiznak@perimeterinstitute.ca [Perimeter Institute, 31 Caroline St. N., Waterloo, Ontario, N2L 2Y5 (Canada); Department of Physics and Astronomy, University of Waterloo, Waterloo, Ontario, N2L 3G1 (Canada); Mann, Robert B., E-mail: rbmann@uwaterloo.ca [Department of Physics and Astronomy, University of Waterloo, Waterloo, Ontario, N2L 3G1 (Canada); Musoke, Nathan, E-mail: nmusoke@perimeterinstitute.ca [Perimeter Institute, 31 Caroline St. N., Waterloo, Ontario, N2L 2Y5 (Canada)

    2016-02-15

    We apply the hyperboloid membrane limit to the general Kerr-AdS metrics and their recently studied super-entropic cousins and obtain a new class of rotating black holes, for which the rotational parameters in multiple directions attain their maximal value—equal to the AdS radius. These new solutions have a potential application in the description of holographic fluids with vorticity. They also possess interesting thermodynamic properties: we show that—despite the absence of Misner strings—the Bekenstein–Hawking entropy/area law is still violated, raising a question about the origin of this violation.

  6. Ultraspinning limits and rotating hyperboloid membranes

    Directory of Open Access Journals (Sweden)

    Robie A. Hennigar

    2016-02-01

    Full Text Available We apply the hyperboloid membrane limit to the general Kerr-AdS metrics and their recently studied super-entropic cousins and obtain a new class of rotating black holes, for which the rotational parameters in multiple directions attain their maximal value—equal to the AdS radius. These new solutions have a potential application in the description of holographic fluids with vorticity. They also possess interesting thermodynamic properties: we show that—despite the absence of Misner strings—the Bekenstein–Hawking entropy/area law is still violated, raising a question about the origin of this violation.

  7. Internal limiting membrane peeling in vitreo-retinal surgery.

    Science.gov (United States)

    Abdelkader, Ehab; Lois, Noemi

    2008-01-01

    Peeling the internal limiting membrane of the retina has become a very common procedure performed by vitreo-retinal surgeons. The combination of new microsurgical instrumentation with the availability of different dyes to stain this thin and transparent membrane has facilitated the performance of internal limiting membrane peeling, reducing the time and trauma associated with this maneuver. Internal limiting membrane peeling has been used to treat a variety of retinal pathologies, including full-thickness macular hole, epiretinal membrane, macular edema, vitreomacular traction syndrome, and Terson syndrome, among others. Although it appears that peeling the internal limiting membrane in these retinal conditions may be associated with better anatomical and visual outcomes following surgery, further evidence through randomized controlled clinical trials is still needed to guide the vitreo-retinal surgeon on the appropriate use of this surgical maneuver.

  8. 10 CFR 34.21 - Limits on external radiation levels from storage containers and source changers.

    Science.gov (United States)

    2010-01-01

    ... 10 Energy 1 2010-01-01 2010-01-01 false Limits on external radiation levels from storage... INDUSTRIAL RADIOGRAPHY AND RADIATION SAFETY REQUIREMENTS FOR INDUSTRIAL RADIOGRAPHIC OPERATIONS Equipment § 34.21 Limits on external radiation levels from storage containers and source changers. The...

  9. Cavernous Hemangioma of the External Canal, Tympanic Membrane, and Middle Ear Cleft: A Case Report.

    Science.gov (United States)

    Odat, Haitham; Al-Qudah, Mohannad; Al-Qudah, Mohammad A

    2016-06-01

    Cavernous hemangioma involving the external canal, tympanic membrane, and middle ear cavity is extremely rare. We present a case of a 45-year-old woman who had progressive right sided decreased hearing, pulsatile tinnitus, and aural fullness of 7 months duration. Microscopic examination, imaging studies, surgical treatment, and histological evaluation are reported. To the best of our knowledge, this is the first case of cavernous hemangioma with simultaneous involvement of the external ear, tympanic membrane, middle ear, and attic reported in English literature.

  10. A novel composite conductive microfiltration membrane and its anti-fouling performance with an external electric field in membrane bioreactors

    Science.gov (United States)

    Huang, Jian; Wang, Zhiwei; Zhang, Junyao; Zhang, Xingran; Ma, Jinxing; Wu, Zhichao

    2015-03-01

    Membrane fouling remains an obstacle to wide-spread applications of membrane bioreactors (MBRs) for wastewater treatment and reclamation. Herein, we report a simple method to prepare a composite conductive microfiltration (MF) membrane by introducing a stainless steel mesh into a polymeric MF membrane and to effectively control its fouling by applying an external electric field. Linear sweep voltammetry and electrochemical impedance spectroscopy analyses showed that this conductive membrane had very good electrochemical properties. Batch tests demonstrated its anti-fouling ability in filtration of bovine serum albumin, sodium alginate, humic acid and silicon dioxide particles as model foulants. The fouling rate in continuous-flow MBRs treating wastewater was also decreased by about 50% for this conductive membrane with 2 V/cm electric field compared to the control test during long-term operation. The enhanced electrostatic repulsive force between foulants and membrane, in-situ cleaning by H2O2 generated from oxygen reduction, and decreased production of soluble microbial products and extracellular polymeric substances contributed to fouling mitigation in this MBR. The results of this study shed light on the control strategy of membrane fouling for achieving a sustainable operation of MBRs.

  11. Limit policies in N-sector dynamic growth games with externalities

    Directory of Open Access Journals (Sweden)

    Ronald D. Fischer

    1997-01-01

    Full Text Available We examine an economy with n production sectors that interact via a production externality. We find a solution to the resulting dynamic differential game between sectors and compare it to the cooperative solution. As the number of sectors increases, the limiting policy is the optimal policy without a production externality. This policy is inefficient and, depending on the sign of the externality between sectors, the inefficiency is due to over- (or under- consumption.

  12. Inverted Internal Limiting Membrane Flap For Large Traumatic Macular Holes.

    Science.gov (United States)

    Abou Shousha, Mohsen Ahmed

    2016-01-01

    The aim of the study was to assess the role of inverted internal limiting membrane flap as a treatment option for large traumatic macular holes.This is a prospective noncomparative study in which 12 eyes with large traumatic macular holes (basal diameter of 1300-2800 μm) since 3 to 6 months were subjected to standard 23-gauge vitrectomy with removal of the posterior hyaloid, brilliant blue G (BBG)-assisted internal limiting membrane peeling in a circular fashion keeping it attached to the edge of the hole to create a flap. At the end of the surgery, air fluid exchange was done with inversion of the internal limiting membrane flap inside the macular hole using the soft tipped cannula and sulfur hexafluoride 20% as tamponade. The main follow-up measures are the best corrected visual acuity and the optical coherence tomography for 6 to 9 months.All the included eyes had a closed hole from the first week postoperative and along the follow-up period (6-9 months). The best corrected visual acuity improved from 20/2000 to 20/200 with a median of 20/400 preoperatively to 20/400 to 20/50 with a median of 20/100 at the end of follow-up period.Inverted internal limiting membrane flap is a good adjuvant to standard vitrectomy in the management of large traumatic macular holes that led to the 100% closure rate and improvement of best corrected visual acuity.

  13. On the limiting behavior of a harmonic oscillator with random external disturbance

    Directory of Open Access Journals (Sweden)

    G. L. Kulinich

    1995-01-01

    Full Text Available This paper deals with the limiting behavior of a harmonic oscillator under the external random disturbance that is a process of the white noise type. Influence of noises is investigated in resonance and non-resonance cases.

  14. Inorganic nitrogen removal of toilet wastewater with an airlift external circulation membrane bioreactor

    Institute of Scientific and Technical Information of China (English)

    LI Gang; WU Lin-lin; DONG Chun-song; WU Guang-xia; FAN Yao-bo

    2007-01-01

    Removal of inorganic nitrogen (inorganic-N) removal of toilet wastewater with a pilot-scale airlift external circulation membrane bioreactor (AEC-MBR) was studied in this paper. The results showed that in the AEC-MBR, with a limited addition of alkalinity and the volumetric loading rates of inorganic-N at 0.19-0.40 kg inorganic-N/(m3·d), the desired nitrification and denitrification were achieved. Furthermore, the effects of pH and DO on inorganic-N removal were examined. Under the condition of MLSS at 1.56-2.35 g/L, BOD5/NH4+-N at 1.0, pH at 7.0-7.5 and DO at 1.0-2.0 mg/L, the removal efficiencies of NH4+-N and inorganic-N were 91.5% and 70.0% respectively in the AEC-MBR. The cost of addition of alkaline reagent was approximately 0.5-1.5 RMB Yuan/m3,and the energy consumption was approximately 0.72 kWh/m3 at the flux of 8 L/(m2·h).

  15. Recurrent myopic foveoschisis: resolution after internal limiting membrane removal

    Directory of Open Access Journals (Sweden)

    Renato Antunes Schiave Germano

    2015-02-01

    Full Text Available We report a case of a 66-year-old man with a history of high myopia and who was referred for acute decreased visual acuity of the right eye. Fundus examination and optical coherence tomography (OCT showed a mild epiretinal membrane (ERM and splitting of retinal layers. Pars plana vitrectomy was performed with intravitreous triamcinolone injection, posterior hyaloid and ERM peeling, and 12% perfluoropropane (C3F8 gas tamponade. After remaining asymptomatic for 17 months, the patient reported a new episode of sudden decreased visual acuity in his right eye, and OCT showed recurrent myopic foveoschisis (MF. He underwent vitrectomy and internal limiting membrane (ILM peeling. Six months later, the patient’s best corrected visual acuity had improved to 20/25. Optical coherence tomography showed a remarkably improved macular anatomy, with residual traction along the inferotemporal arcade, which was attributed to the vessel stiffness itself. We conclude that removing the internal limiting membrane is a challenging maneuver in myopic foveoschisis, even with staining approaches. Although myopic foveoschisis may be resolved without peeling the internal limiting membrane, its removal should be considered if the condition recurs.

  16. Novel filtration mode for fouling limitation in membrane bioreactors.

    Science.gov (United States)

    Wu, Jinling; Le-Clech, Pierre; Stuetz, Richard M; Fane, Anthony G; Chen, Vicki

    2008-08-01

    A novel filtration mode is presented to reduce fouling propensity in membrane bioreactors (MBR). During this mode, an elevated high instantaneous flux (60Lm(-2)h(-1)) is initially applied for a short time (120s), followed by a longer filtration (290s) at lower flux (10.3Lm(-2)h(-1)) and a backwash in each filtration cycle. The mixed mode is expected to limit irreversible fouling as the reversible fouling created during the initial stage appears to protect the membrane. Hydraulic performance and the components of foulants were analyzed and compared with conventional continuous and backwash modes. It was found that the mixed mode featured lower trans-membrane pressure (TMP) after 24h of filtration when compared to other modes. The mixed mode was effective in preventing soluble microbial products (SMP) attaching directly onto the membrane surface, keeping the cake layer weakly compressed, and reducing the mixed liquor suspended solids (MLSS) accumulation on the membrane. This strategy reduced the resistances of both the cake layer and the gel layer. A factorial experimental design was carried out for eight runs with different conditions to identify the major operational parameters affecting the hydraulic performances. The results showed that the value of the flux in the initial high-flux period had the most effect on the performance of the mixed mode: high initial flux (60Lm(-2)h(-1)) led to improved performance.

  17. Crystal structure of HIV-1 gp41 including both fusion peptide and membrane proximal external regions.

    Directory of Open Access Journals (Sweden)

    Victor Buzon

    2010-05-01

    Full Text Available The HIV-1 envelope glycoprotein (Env composed of the receptor binding domain gp120 and the fusion protein subunit gp41 catalyzes virus entry and is a major target for therapeutic intervention and for neutralizing antibodies. Env interactions with cellular receptors trigger refolding of gp41, which induces close apposition of viral and cellular membranes leading to membrane fusion. The energy released during refolding is used to overcome the kinetic barrier and drives the fusion reaction. Here, we report the crystal structure at 2 A resolution of the complete extracellular domain of gp41 lacking the fusion peptide and the cystein-linked loop. Both the fusion peptide proximal region (FPPR and the membrane proximal external region (MPER form helical extensions from the gp41 six-helical bundle core structure. The lack of regular coiled-coil interactions within FPPR and MPER splay this end of the structure apart while positioning the fusion peptide towards the outside of the six-helical bundle and exposing conserved hydrophobic MPER residues. Unexpectedly, the section of the MPER, which is juxtaposed to the transmembrane region (TMR, bends in a 90 degrees-angle sideward positioning three aromatic side chains per monomer for membrane insertion. We calculate that this structural motif might facilitate the generation of membrane curvature on the viral membrane. The presence of FPPR and MPER increases the melting temperature of gp41 significantly in comparison to the core structure of gp41. Thus, our data indicate that the ordered assembly of FPPR and MPER beyond the core contributes energy to the membrane fusion reaction. Furthermore, we provide the first structural evidence that part of MPER will be membrane inserted within trimeric gp41. We propose that this framework has important implications for membrane bending on the viral membrane, which is required for fusion and could provide a platform for epitope and lipid bilayer recognition for broadly

  18. Intense Internal and External Fluorescence as Solar Cells Approach the Shockley-Queisser Efficiency Limit

    CERN Document Server

    Miller, Owen D; Kurtz, Sarah R

    2012-01-01

    Absorbed sunlight in a solar cell produces electrons and holes. But, at the open circuit condition, the carriers have no place to go. They build up in density and, ideally, they emit external fluorescence that exactly balances the incoming sunlight. Any additional non-radiative recombination impairs the carrier density buildup, limiting the open-circuit voltage. At open-circuit, efficient external fluorescence is an indicator of low internal optical losses. Thus efficient external fluorescence is, counter-intuitively, a necessity for approaching the Shockley-Queisser efficiency limit. A great Solar Cell also needs to be a great Light Emitting Diode. Owing to the narrow escape cone for light, efficient external emission requires repeated attempts, and demands an internal luminescence efficiency >>90%.

  19. Retinal Damage Induced by Internal Limiting Membrane Removal

    Directory of Open Access Journals (Sweden)

    Rachel Gelman

    2015-01-01

    Full Text Available The internal limiting membrane (ILM, the basement membrane of the Müller cells, serves as the interface between the vitreous body and the retinal nerve fiber layer. It has a fundamental role in the development, structure, and function of the retina, although it also is a pathologic component in the various vitreoretinal disorders, most notably in macular holes. It was not until understanding of the evolution of idiopathic macular holes and the advent of idiopathic macular hole surgery that the idea of adjuvant ILM peeling in the treatment of tractional maculopathies was explored. Today intentional ILM peeling is a commonly applied surgical technique among vitreoretinal surgeons as it has been found to increase the rate of successful macular hole closure and improve surgical outcomes in other vitreoretinal diseases. Though ILM peeling has refined surgery for tractional maculopathies, like all surgical procedures it is not immune to perioperative risk. The essential role of the ILM to the integrity of the retina and risk of trauma to retinal tissue spurs suspicion with regard to its routine removal. Several authors have investigated the retinal damage induced by ILM peeling and these complications have been manifested across many different diagnostic studies.

  20. Unified solution of limit loads of thick wall cylinder subject to external pressure considering strain softening

    Institute of Scientific and Technical Information of China (English)

    CHEN Changfu; XIAO Shujun; YANG Yu

    2007-01-01

    Based on the unified strength theory [1],a unified strength criterion for strain softening materials,such as concrete or rock,was derived,and the elastic and plastic limit loads of a thick-walled cylinder made of these materials subject to external pressure were also given.In addition,the influence of some factors on the limit loads of such cylinders as the ratio of the external radius to intemal radius,rb/ra,the coefficient b,which reflects the effect of medium principal stress and the normal stress of the relevant surface on the material destroy degree,the ratio of tensile strength to compressed strength of the material,α,and the damage variable β were discussed in detail.Some examples were given and some meaningful results were obtained.

  1. External fixation combined with limited internal fixation in the treatment of pilon tibia fractures

    Directory of Open Access Journals (Sweden)

    Golubović Zoran

    2007-01-01

    Full Text Available Background/Aim. Intraarticular fractures of the tibial plafond (pilon fractures belong to the group of most severe fractures. They are usually caused by high-energy trauma and frequently associated with a marked soft-tissue damage. Surgical treatment has replaced the traditional nonoperative treatment. The aim of this study was to present the results of the treatment of distal tibial intraarticular fracture by the use of internal fixation, as well as the combination of minimal internal fixation and external fixation. Methods. The study included 47 patients with pilon tibia fractures who went through at the Clinic for Orthopedics and Traumatology, School of Medicine, Niš (1995-2004. Within the analyzed group there were 33 (70.2% males and 14 (29.8% females. The patients mean age was 45.8 years. In the first group, which consisted of 22 patients, open reduction and internal fixation of both the tibia and the fibula was performed in the two separate incisions. The second group consisted of 25 patients managed with external fixation by external fixator "Mitković" with limited internal fixation. Besides external fixation, a minimal internal fixation was performed by the use of Kirschner wires and screws. The patients were followed-up inside a 24-months-period. Results. The obtained was a substantially high number of complications after open reduction and internal fixation in the group of patients. There was no difference in a long-term clinical outcome. Postoperative osteitis, as the most severe complication in the management of closed pilon tibia fractures, was not registered in the second group. Conclusion. Considering the results obtained in this study, it can be concluded that external fixation by the "Mitković" external fixator with the minimal internal fixation is a satisfactory method for the treatment of fractures of the tibial plafond causing less complications than internal fixation. .

  2. Some limitations on the external validity of psychotherapy efficacy studies and suggestions for future research.

    Science.gov (United States)

    Shean, Glenn D

    2012-01-01

    Increased emphasis on identifying empirically supported treatments (ESTs) has enhanced the scientific basis for psychotherapy practice, but uncritical acceptance of ESTs as the basis for credentialing and policy decisions risks stifling innovation and creativity in the field. There are limitations inherent in efficacy studies of psychotherapy that can constrain external validity. This article discusses several limitations on the external validity of efficacy studies, as well as other issues related to evaluating psychotherapy outcome research. These limitations and concerns include: 1) the practice of maximizing homogeneity by selecting participants diagnosed with a single Axis I disorder; 2) the practice of requiring manualized therapies for efficacy research; 3) the assumption that lasting and meaningful changes occur and can be assessed within a relatively short time frame; 4) the assumption that valid assessments of outcome can be conducted in randomized control trials studies without concern for researcher allegiance; and 5) the view that evidence of effectiveness from non-RCT design studies can be ignored. Finally, alternative research approaches for studying psychotherapy that can potentially supplement knowledge gained from efficacy studies and foster continued innovation and creativity in the field are discussed.

  3. Beta limits against external kink modes in tokamaks taking into account plasma outside separatrix

    Energy Technology Data Exchange (ETDEWEB)

    Degtyarev, L.; Martynov, A.; Medvedev, S. [Keldysh Inst. of Applied Mathematics, Russian Academy of Sciences, Moscow (Russian Federation); Villard, L. [Ecole Polytechnique Federale, Lausanne (Switzerland). Centre de Recherche en Physique des Plasma (CRPP)

    1997-06-01

    The pressure profile variation in relatively thin plasma layer outside the separatrix can influence global external kink mode stability and considerably change the {beta} limit in doublet configurations. The conclusions for divertor configurations strongly depend on the choice of boundary conditions at the open field lines. Fixed boundary conditions at the divertor end plates result in stabilizing effect of the plasma outside separatrix independent of pressure gradient there. More realistic choice of boundary conditions gives a behavior similar to the doublet case. (author) 3 figs., 5 refs.

  4. Flexible magnetic filaments under the influence of external magnetic fields in the limit of infinite dilution.

    Science.gov (United States)

    Cerdà, Joan J; Sánchez, Pedro A; Lüsebrink, Daniel; Kantorovich, Sofia; Sintes, Tomàs

    2016-05-14

    In the present work we use Langevin dynamics computer simulations to understand how the presence of a constant external magnetic field modifies the conformational phase diagram of magnetic filaments in the limit of infinite dilution. We have considered the filaments immersed in either a good (non-sticky filaments) or a poor (Stockmayer polymers) solvent. It has been found that in the presence of an applied field, filaments turn out to be much more susceptible to parameters such as temperature and solvent conditions. Filaments owe this increased susceptibility to the fact that the external magnetic field tends to level the free energy landscape as compared to the zero-field case. The field induces equalization in the free energy of competing conformational states that were separated by large energy differences in the zero-field limit. In this new scenario multistability arises, and manifests itself in the existence of broad regions in the phase diagram where two or more equilibrium configurations coexist. The existence of multistability greatly enhances the possibility of tuning the properties of the filament.

  5. Long-dated evaluation of the external costs of the nuclear; L'evaluation des couts externes a long terme de la filiere nucleaire: interets et limites

    Energy Technology Data Exchange (ETDEWEB)

    Le Dars, A.; Schneider, T

    2002-09-01

    Since the middle of the years 1990, the European Commission developed an ''ExternE'' methodology to propose an homogenous evaluation of the sanitary and environmental external costs of the various energy sectors in Europe. This document discusses the taking into account of the long-dated and analyzes the interests and the limits of the monetary evaluation, in terms of external costs, of the nuclear choice. It is organized in three chapters: 1. a presentation and a discussion on the various evaluation of the ''ExternE'' methodology; 2. a description of the available methods for the monetary evaluation of the long-dated impacts and more particularly the analysis of the monetary values actualization principle; 3. highlighted of the impacts for which the monetary evaluations exist. (A.L.B.)

  6. Treatment of Gustilo grade Ⅲ leg fractures by external fixation associated with limited internal fixation

    Institute of Scientific and Technical Information of China (English)

    ZHANG Chun-qiang; ZHENG Hong-yu; WANG Bing; HUANG He; HE Fei; ZHAO Xue-ling

    2010-01-01

    Objective: To explore the clinical ef-fects of external fixation associated with limited internal fixa-tion on treatment of Gustilo grade Ⅲ leg fractures.Methods: From July 2006 to December 2008, 40 cases of Gustilo grade Ⅲ leg fiactures were emergently treated in our unit with external fixation frames.Soft tissue injuries were grouped according to the Gustilo classification as ⅢA in 17 cases, ⅢB in 13 cases, and ⅢC in 10 cases.All the patients were debrided within 8 hours, and then fracture reposition was preformed to reestablish the leg alignment.Limited internal fixation with plates and screws were per-formed on all the Gustilo Ilia cases and 10 Gustilo ⅢB cases at the first operation.But all the Gustilo ⅢC cases and 3 Gustilo ⅢB cases who had severe soft tissue injuries and bone loss only received Vacuum-sealing drainage (VSD).Broad-spectrum antibiotics were regularly used and VSD must be especially maintained easy and smooth for one week or more after operation.Limited internal fixation and transplanted free skin flaps or adjacent musculocutaneous flaps were not used to close wounds until the conditions of the wounds had been improved.Results: The first operations were completed within 90-210 minutes (170 minutes on average).The blood trans-fusions were from 400 ml to 1500 ml (those used for anti-shock preoperatively not included).All the 40 patients in this study were followed up for 6-28 months, 20.5 months on average.The lower limb function was evaluated accord-ing to the comprehensive evaluation standards of leg func-tion one year after operation and the results of 28 cases were excellent, 9 were good and 3 were poor.Conclusion: External fixation associated with limited internal fixation to treat Gustilo grade Ⅲ leg fractures can get satisfactory early clinical therapeutic effects.

  7. Vitrectomy and internal limiting membrane peeling with different vitreous tamponade for idiopathic macular epiretinal membrane

    Directory of Open Access Journals (Sweden)

    Jie Dong

    2013-06-01

    Full Text Available AIM: To compare visual outcomes, central foveal thickness(CFT, and postoperative complications after vitrectomy and internal limiting membrane(ILMpeeling, with balanced salt solution(BSSor gas tamponade, for the treatment of idiopathic macular epiretinal membrane(IMEM. METHODS: Retrospective clinical study. 44 patients with IMEM were included in this study. All patients had undergone vitrectomy and ILM peeling. Eyes were divided into two groups: 20 eyes in group A with BSS tamponade. 24 patients in group B with gas tamponade(11 eyes were injected with filtered air and 13 eyes with perfluoropropane,100mL/L C3F8. The follow-up period was 12-16(mean 13months. The following parameters were collected and compared: best-corrected visual acuity(BCVAand CFT(at baseline and 1, 3, 6 and 12 months postoperatively, intraocular pressure(IOP(at baseline and on the 1th,7th day, 1, 3 months postoperatively. RESULTS: BCVA significantly improved, and 29 of 44 eyes(65.9%achieved visual recovery≥0.2 logMAR. There were no significant differences between group A and group B in mean baseline logMAR BCVA(0.53±0.18 vs 0.52±0.14; P>0.05and final logMAR BCVA(0.31±0.14 vs 0.28±0.09; P>0.05. With respect to OCT parameters, the mean CFT at 12 months(285.25±70.07μmwas significantly decreased from that of the baseline(407.82±97.00μm,(Z=4.29, Pvs 406.46±88.76μm; P>0.05and final CFT(287.60±66.94μm vs 283.29±73.95μm; P>0.05. With respect to IOP, there were no significant differences between group A and group B at mean baseline and on the 7th day, 1, 3 months postoperatively(P>0.05. The IOP in group A was significant lower at 1th postoperative day compared with group B(Z=3.12, PCONCLUSION: Vitrectomy and ILM peeling can significantly improve the visual acuity and decrease the CFT no matter with gas or with BSS tamponade, there were no significant differences in clinical outcomes, but it is neither necessary for patients with BSS tamponade to maintain a prone

  8. Structural Characterization of HIV gp41 with the Membrane-proximal External Region

    Energy Technology Data Exchange (ETDEWEB)

    Shi, W.; Bohon, J; Han, D; Habte, H; Qin, Y; Cho, M; Chance, M

    2010-01-01

    Human immunodeficiency virus, type 1 (HIV-1) envelope glycoprotein (gp120/gp41) plays a critical role in virus infection and pathogenesis. Three of the six monoclonal antibodies considered to have broadly neutralizing activities (2F5, 4E10, and Z13e1) bind to the membrane-proximal external region (MPER) of gp41. This makes the MPER a desirable template for developing immunogens that can elicit antibodies with properties similar to these monoclonal antibodies, with a long term goal of developing antigens that could serve as novel HIV vaccines. In order to provide a structural basis for rational antigen design, an MPER construct, HR1-54Q, was generated for x-ray crystallographic and x-ray footprinting studies to provide both high resolution atomic coordinates and verification of the solution state of the antigen, respectively. The crystal structure of HR1-54Q reveals a trimeric, coiled-coil six-helical bundle, which probably represents a postfusion form of gp41. The MPER portion extends from HR2 in continuation of a slightly bent long helix and is relatively flexible. The structures observed for the 2F5 and 4E10 epitopes agree well with existing structural data, and enzyme-linked immunosorbent assays indicate that the antigen binds well to antibodies that recognize the above epitopes. Hydroxyl radical-mediated protein footprinting of the antigen in solution reveals specifically protected and accessible regions consistent with the predictions based on the trimeric structure from the crystallographic data. Overall, the HR1-54Q antigen, as characterized by crystallography and footprinting, represents a postfusion, trimeric form of HIV gp41, and its structure provides a rational basis for gp41 antigen design suitable for HIV vaccine development.

  9. Abduction and external rotation (ABER) MR arthrography of the shoulder. Benefits and limitations

    Energy Technology Data Exchange (ETDEWEB)

    Mostafa, A.; Gokan, Takehiko; Munechika, Hirotsugu; Ogawa, Takashi [Showa Univ., Tokyo (Japan). School of Medicine; El-Feky, A.A.

    2001-12-01

    The purpose of this study was to show the benefits and limitations of using abduction and external rotation (ABER) positions of the arm during MR arthrography of the shoulder in the evaluation of the rotator-cuff tendon, the capsulolabral complex and the shoulder joint after surgery. Forty-seven patients complaining of either shoulder instability, chronic shoulder pain, pain of unknown cause or pain following shoulder surgery were studied using the direct MR arthrography technique in both the standard neutral position with the arm adducted as well as with the arm in the ABER position. A correlation was obtained between the MR arthrography findings and the surgical findings in 10 reports and clinical presentations of the examined patients. Three patients [6%] were unable to perform ABER positioning. ABER oblique axial images were better than standard oblique coronal images in revealing undersurface tears of the rotator cuff particularly of the grade I type. Four tears were missed in standard images. Oblique axial images were better than standard axial images in demonstrating non-displaced anterior labral tears. One tear was missed and two tears were suspected in the standard images. Oblique axial images were less sensitive than oblique coronal images in the diagnosis of superior labral tears. Two tears were missed in ABER images. The ABER oblique axial MR arthrogram is a useful adjunct to the standard axial and oblique coronal MR arthrograms for assessment of capsulolabral abnormalities and rotator-cuff tendon tears despite some limitations. (author)

  10. Volumetric gas-liquid mass transfer coefficient in an external-loop airlift reactor with inserted membrane

    Directory of Open Access Journals (Sweden)

    Kojić Predrag S.

    2016-01-01

    Full Text Available The effects of the inserted membrane in the downcomer of an external-loop airlift reactor, the gas sparger type (single orifice and sinter plate and added alcohol (ethanol, n-butanol, or n-hexanol on the volumetric gas-liquid mass transfer coefficient (kLa were studied. Due to the presence of the membrane in the downcomer, kLa did not change significantly; the differences were smaller than 10%. The highest values of the kLa were obtained using the sinter plate. It was found that the addition of small amounts of alcohol increased the mass transfer. Using our experimental results and the data of other authors, the feed-forward back propagation neural network for prediction of kLa in external-loop airlift reactors with alcohol solutions was proposed. [Projekat Ministarstva nauke Republike Srbije, br. 172025

  11. The Preliminary Report of Pathological Changes of Epiretinal Membranes and Internal Limiting Membrane Removed during Idiopathic Macular Hole Surgery

    Institute of Scientific and Technical Information of China (English)

    Jiaqing Li; Shibo Tang; Yan Luo; Jie Zhang; Shaofen Lin

    2002-01-01

    Purpose:To investigate the pathological changes of epiretinal membranes(ERM)and internal limiting membrane (ILM) removed during idiopathic macular hole surgery.Methods:Ten consecutive patients with a unilateral idiopathic macular hole underwent pars plana vitrectomy(PPV) with the surgical removal of the ERMs overlying the hole and ILM surrounding the hole. The pathological features of the excised tissues were examined under the microscope. Results:According to the morphological changes, four ERMs showed cellular elements which looked like glia cells, macrophages, plasma cells, lymphocytes and fibroblast cells. Two of the ILM appeared as transparent membranes without cellular elements. The other eight ILM showed cellular elements on the transparent membranes.Conclusion: Our study supports the hypothesis that the tangential traction of vitreous and proliferative cellular elements on the inner surface of ILM causes idiopathic macular holes. Removal of the posterior cortical vitreous, ILM and proliferative cellular tissue is a valid treatment for IMH.

  12. Fluctuation Limit for Interacting Diffusions with Partial Annihilations Through Membranes

    Science.gov (United States)

    Chen, Zhen-Qing; Fan, Wai-Tong Louis

    2016-08-01

    We study fluctuations of the empirical processes of a non-equilibrium interacting particle system consisting of two species over a domain that is recently introduced in Chen and Fan (Ann Probab, to appear) and establish its functional central limit theorem. This fluctuation limit is a distribution-valued Gaussian Markov process which can be represented as a mild solution of a stochastic partial differential equation. The drift of our fluctuation limit involves a new partial differential equation with nonlinear coupled term on the interface that characterized the hydrodynamic limit of the system. The covariance structure of the Gaussian part consists two parts, one involving the spatial motion of the particles inside the domain and other involving a boundary integral term that captures the boundary interactions between two species. The key is to show that the Boltzmann-Gibbs principle holds for our non-equilibrium system. Our proof relies on generalizing the usual correlation functions to the join correlations at two different times.

  13. A Method to Solve the Limitations in Drawing External Rays of the Mandelbrot Set

    Directory of Open Access Journals (Sweden)

    M. Romera

    2013-01-01

    Full Text Available The external rays of the Mandelbrot set are a valuable graphic tool in order to study this set. They are drawn using computer programs starting from the Böttcher coordinate. However, the drawing of an external ray cannot be completed because it reaches a point from which the drawing tool cannot continue drawing. This point is influenced by the resolution of the standard for floating-point computation used by the drawing program. The IEEE 754 Standard for Floating-Point Arithmetic is the most widely used standard for floating-point computation, and we analyze the possibilities of the quadruple 128 bits format of the current IEEE 754-2008 Standard in order to draw external rays. When the drawing is not possible, due to a lack of resolution of this standard, we introduce a method to draw external rays based on the escape lines and Bézier curves.

  14. Pushing the lipid envelope: using bio-inspired nanocomposites to understand and exploit lipid membrane limitations

    Science.gov (United States)

    Montano, Gabriel

    Lipids serve as the organizing matrix material for biological membranes, the site of interaction of cells with the external environment. . As such, lipids play a critical role in structure/function relationships of an extraordinary number of critical biological processes. In this talk, we will look at bio-inspired membrane assemblies to better understand the roles of lipids in biological systems as well as attempt to generate materials that can mimic and potentially advance upon biological membrane processes. First, we will investigate the response of lipids to adverse conditions. In particular, I will present data that demonstrates the response of lipids to harsh conditions and how such responses can be exploited to generate nanocomposite rearrangements. I will also show the effect of adding the endotoxin lipopolysaccharide (LPS) to lipid bilayer assemblies and describe implications on our understanding of LPS organization in biological systems as well as describe induced lipid modifications that can be exploited to organize membrane composites with precise, two-dimensional geometric control. Lastly, I will describe the use of amphiphilic block copolymers to create membrane nanocomposites capable of mimicking biological systems. In particular, I will describe the use of our polymer-based membranes in creating artificial photosynthetic assemblies that rival biological systems in function in a more flexible, dynamic matrix.

  15. Thrombus imaging in a primate model with antibodies specific for an external membrane protein of activated platelets

    Energy Technology Data Exchange (ETDEWEB)

    Palabrica, T.M.; Furie, B.C.; Konstam, M.A.; Aronovitz, M.J.; Connolly, R.; Brockway, B.A.; Ramberg, K.L.; Furie, B.

    1989-02-01

    The activated platelet is a potential target for the localization of thrombi in vivo since, after stimulation and secretion of granule contents, activated platelets are concentrated at sites of blood clot formation. In this study, we used antibodies specific for a membrane protein of activated platelets to detect experimental thrombi in an animal model. PADGEM (platelet activation-dependent granule-external membrane protein), a platelet alpha-granule membrane protein, is translocated to the plasma membrane during platelet activation and granule secretion. Since PADGEM is internal in unstimulated platelets, polyclonal anti-PADGEM and monoclonal KC4 antibodies do not bind to circulating resting platelets but do interact with activated platelets. Dacron graft material incubated with radiolabeled KC4 or anti-PADGEM antibodies in the presence of thrombin-activated platelet-rich plasma bound most of the antibody. Imaging experiments with 123I-labeled anti-PADGEM in baboons with an external arterial-venous Dacron shunt revealed rapid uptake in the thrombus induced by the Dacron graft; control experiments with 123I-labeled nonimmune IgG exhibited minimal uptake. Deep venous thrombi, formed by using percutaneous balloon catheters to stop blood flow in the femoral vein of baboons, were visualized with 123I-labeled anti-PADGEM. Thrombi were discernible against blood pool background activity without subtraction techniques within 1 hr. No target enhancement was seen with 123I-labeled nonimmune IgG. 123I-labeled anti-PADGEM cleared the blood pool with an initial half-disappearance time of 6 min and did not interfere with hemostasis. These results indicate that radioimmunoscintigraphy with anti-PADGEM antibodies can visualize thrombi in baboon models and is a promising technique for clinical thrombus detection in humans.

  16. Effect of ceramic membrane channel diameter on limiting retentate protein concentration during skim milk microfiltration.

    Science.gov (United States)

    Adams, Michael C; Barbano, David M

    2016-01-01

    Our objective was to determine the effect of retentate flow channel diameter (4 or 6mm) of nongraded permeability 100-nm pore size ceramic membranes operated in nonuniform transmembrane pressure mode on the limiting retentate protein concentration (LRPC) while microfiltering (MF) skim milk at a temperature of 50°C, a flux of 55 kg · m(-2) · h(-1), and an average cross-flow velocity of 7 m · s(-1). At the above conditions, the retentate true protein concentration was incrementally increased from 7 to 11.5%. When temperature, flux, and average cross-flow velocity were controlled, ceramic membrane retentate flow channel diameter did not affect the LRPC. This indicates that LRPC is not a function of the Reynolds number. Computational fluid dynamics data, which indicated that both membranes had similar radial velocity profiles within their retentate flow channels, supported this finding. Membranes with 6-mm flow channels can be operated at a lower pressure decrease from membrane inlet to membrane outlet (ΔP) or at a higher cross-flow velocity, depending on which is controlled, than membranes with 4-mm flow channels. This implies that 6-mm membranes could achieve a higher LRPC than 4-mm membranes at the same ΔP due to an increase in cross-flow velocity. In theory, the higher LRPC of the 6-mm membranes could facilitate 95% serum protein removal in 2 MF stages with diafiltration between stages if no serum protein were rejected by the membrane. At the same flux, retentate protein concentration, and average cross-flow velocity, 4-mm membranes require 21% more energy to remove a given amount of permeate than 6-mm membranes, despite the lower surface area of the 6-mm membranes. Equations to predict skim milk MF retentate viscosity as a function of protein concentration and temperature are provided. Retentate viscosity, retentate recirculation pump frequency required to maintain a given cross-flow velocity at a given retentate viscosity, and retentate protein

  17. Externalizing the EU’s Justice and Home Affairs to Southeast Asia: Prospects and Limitations

    Directory of Open Access Journals (Sweden)

    Felix Heiduk

    2016-08-01

    Full Text Available The transnational security dimension ascribed to many phenomena such as terrorism, drug trafficking, pandemics, or people smuggling has led to increased pressures to increase cooperation across national borders to ‘fight’ or ‘manage’ many of the new, transnational security threats. Against this background the EU has sought to promote its own norms and ideas, policy preferences and its own model of regional cooperation and integration in her external affairs. A number of recent studies have examined the growing potency of the EU to actively promote ideas and policy preferences in its neighborhood as well as with the U.S., however, scant attention has been given to EU cooperation with other regional organizations. By closely examining the EU’s cooperation with ASEAN in two policy fields deemed central within JHA – human trafficking and counter terrorism – this paper seeks not only to broaden the empirical basis of scholarship, but additionally seeks to connect the empirical findings with the wider debate on the EU’s ability to externalize its internal security governance. The study finds that despite numerous declarations and plan of actions, very little policy transfer has actually taken place between the EU and ASEAN. It is argued that any attempt to externalize or transfer policy is met by long-standing ideas and norms, policy paradigms and an established specific modus operandi of regional cooperation within ASEAN itself. This will continue to make nigh impossible any externalization of EU policies to Southeast Asia for the foreseeable future.

  18. A criterion for timescale decomposition of external inputs for generalized phase reduction of limit-cycle oscillators

    CERN Document Server

    Kurebayashi, Wataru; Nakao, Hiroya

    2015-01-01

    The phase reduction method is a dimension reduction method for weakly driven limit-cycle oscillators, which has played an important role in the theoretical analysis of synchro- nization phenomena. Recently, we proposed a generalization of the phase reduction method [W. Kurebayashi et al., Phys. Rev. Lett. 111, 2013]. This generalized phase reduction method can robustly predict the dynamics of strongly driven oscillators, for which the conventional phase reduction method fails. In this generalized method, the external input to the oscillator should be properly decomposed into a slowly varying component and remaining weak fluctua- tions. In this paper, we propose a simple criterion for timescale decomposition of the external input, which gives accurate prediction of the phase dynamics and enables us to systematically apply the generalized phase reduction method to a general class of limit-cycle oscillators. The validity of the criterion is confirmed by numerical simulations.

  19. Polymer electrolyte membranes from fluorinated polyisoprene-block-sulfonated polystyrene: Microdomain orientation by external field

    Energy Technology Data Exchange (ETDEWEB)

    Sodeye, Akinbode [Department of Polymer Science and Engineering, University of Massachusetts; Huang, Tianzi [University of Tennessee, Knoxville (UTK); Gido, Samuel [University of Massachusetts, Amherst; Mays, Jimmy [ORNL

    2011-01-01

    In this study, block copolymer ionomers of the cesium salt (20 mol %) of fluorinated polyisoprene-blocksulfonated polystyrene were spin cast into membranes and annealed under an electric field ofw40 V/mm at 130 C for 24 h. The effect of this treatment was a 2.5 times increase in the ionic conductivity as measured by electrochemical impedance spectroscopy, under all humidity conditions measured. This can be attributed to the increased connectivity of the ionic domains of the block copolymers. This E-field alignment technique may thus find application in the fabrication of nanostructured polyelectrolytes with enhanced charge transport capacity.

  20. Macular morphology and visual acuity after macular hole surgery with or without internal limiting membrane peeling

    DEFF Research Database (Denmark)

    Christensen, U.C.; Kroyer, K.; Sander, B.

    2010-01-01

    Aim: To examine postoperative macular morphology and visual outcome after 12 months in relation to internal limiting membrane (ILM) peeling versus no peeling, indocyanine green (ICG) staining and re-operation in eyes that achieved macular hole closure after surgery. Methods: Seventy-four eyes wit...

  1. [Modified technique of autologous transplantation of internal limiting membrane for macular hole].

    Science.gov (United States)

    Hernández-da Mota, Sergio Eustolio; Béjar-Cornejo, Francisco

    Autologous internal limiting membrane transplantation has allowed some cases of macular holes refractory to conventional surgery techniques to be treated. The purpose of this study is to describe the anatomical and functional outcomes of a modification of this technique in a case series of naïve macular hole patients. A consecutive case series study was performed on patients with naïve macular holes with a diameter greater than 600 μ. Best corrected visual acuity, clinical features of the macular area, and optical coherence tomography were recorded before the operation and at the end of follow-up in all patients studied. All patients underwent 23 Ga core vitrectomy, posterior hyaloid separation, and brilliant-blue assisted internal limiting membrane peeling. A small piece of the internal limiting membrane was peeled off to make a free flap, and this was trasplanted and placed inside the macular hole under perfluorocarbon liquids. Air-fluid exchange was performed and SF6 gas was injected at a non-expansile concentration. The study included 5 eyes of 5 patients who underwent internal limiting membrane autograft. The mean age was 50.6 (SD 12.3) years. Four of the 5 cases had macular hole closure. The case where there was no closure of the macular hole was secondary to trauma. There was an improvement in visual acuity in all patients where the closing of the macular hole was achieved at the end of follow-up. In this cases series of macular hole patients, the autologous internal limiting membrane transplantation was associated with an anatomical closure of the macular hole and functional improvement in most of the patients studied. Copyright © 2016 Academia Mexicana de Cirugía A.C. Publicado por Masson Doyma México S.A. All rights reserved.

  2. Externally controlled drug release using a gold nanorod contained composite membrane.

    Science.gov (United States)

    Kim, Kibeom; Jo, Min-Chul; Jeong, Sundo; Palanikumar, L; Rotello, Vincent M; Ryu, Ja-Hyoung; Park, Myoung-Hwan

    2016-06-09

    Versatile drug delivery devices using nanoporous membranes consisting of gold nanorods and dendrimers have been demonstrated to provide light-triggered on-demand pulsatile release from a reservoir containing highly enriched therapeutics for a real patient's needs. The drug release rate is directly correlated with the temperature increase and irradiated energy of a near-IR laser in both static and fluidic devices. This biocompatible platform for on-demand control was further confirmed by in vitro experiments. Interestingly, different responses to stimuli were obtained from each drug in the absence and presence of NIR light, indicating the versatile potential of our on-demand drug delivery system in less-invasive therapies requiring multi-drug delivery strategies. The enhanced delivery system will improve therapeutic efficacy and reduce side effects through regulation of plasma drug profiles.

  3. Externally controlled drug release using a gold nanorod contained composite membrane

    Science.gov (United States)

    Kim, Kibeom; Jo, Min-Chul; Jeong, Sundo; Palanikumar, L.; Rotello, Vincent M.; Ryu, Ja-Hyoung; Park, Myoung-Hwan

    2016-06-01

    Versatile drug delivery devices using nanoporous membranes consisting of gold nanorods and dendrimers have been demonstrated to provide light-triggered on-demand pulsatile release from a reservoir containing highly enriched therapeutics for a real patient's needs. The drug release rate is directly correlated with the temperature increase and irradiated energy of a near-IR laser in both static and fluidic devices. This biocompatible platform for on-demand control was further confirmed by in vitro experiments. Interestingly, different responses to stimuli were obtained from each drug in the absence and presence of NIR light, indicating the versatile potential of our on-demand drug delivery system in less-invasive therapies requiring multi-drug delivery strategies. The enhanced delivery system will improve therapeutic efficacy and reduce side effects through regulation of plasma drug profiles.Versatile drug delivery devices using nanoporous membranes consisting of gold nanorods and dendrimers have been demonstrated to provide light-triggered on-demand pulsatile release from a reservoir containing highly enriched therapeutics for a real patient's needs. The drug release rate is directly correlated with the temperature increase and irradiated energy of a near-IR laser in both static and fluidic devices. This biocompatible platform for on-demand control was further confirmed by in vitro experiments. Interestingly, different responses to stimuli were obtained from each drug in the absence and presence of NIR light, indicating the versatile potential of our on-demand drug delivery system in less-invasive therapies requiring multi-drug delivery strategies. The enhanced delivery system will improve therapeutic efficacy and reduce side effects through regulation of plasma drug profiles. Electronic supplementary information (ESI) available. See DOI: 10.1039/c6nr00362a

  4. Combined epiretinal and internal limiting membrane peeling facilitated by high dilution indocyanine green negative staining

    Directory of Open Access Journals (Sweden)

    Mark M Kaehr

    2015-01-01

    Full Text Available We describe the utilization of indocyanine green (ICG dye to facilitate combined/en bloc removal of epiretinal membranes (ERM along with internal limiting membranes (ILM. The method utilizes a highly diluted preparation of ICG in dextrose water solvent (D5W. Elimination of fluid air exchange step facilitating staining in the fluid phase and low intensity lighting help minimize potential ICG toxicity. The technique demonstrates how ICG facilitates negative staining of ERMs and how ILM peeling concomitantly can allow complete and efficient ERM removal minimizing surgical time and the necessity for dual or sequential staining.

  5. Management of intra-articular fracture of the fingers via mini external fixator combined with limited internal fixation

    Institute of Scientific and Technical Information of China (English)

    LI Wen-jun; TIAN Wen; TIAN Guang-lei; CHEN Shan-lin; ZHANG Chang-qing; XUE Yun-hao; LI Zhong-zhe; ZHU Yin

    2009-01-01

    Background Intra-articular fractures of the fingers are common problems to emergency physicians and hand surgeons.Inappropriate management of these injuries may result in chronic pain,stiffness,deformity,or post traumatic arthritis.Ideal treatment necessitates the restoration of a stable and congruent joint that will allow early mobilization.The purpose of this study was to investigate the results of intra-articular fracture of the fingers by mini external fixator combined with limited internal fixation.Methods From May 2005 to May 2007,a total of 26 patients with intra-articular fracture of the fingers were treated by mini external fixator combined with limited internal fixation.Of the 26 cases,11 involved in metacarpophalangeal joint,and 15 interphalangeal joint in proximal interphalangeal.Kirschner wire,mini wire and absorbable suture were used for limited internal fixation.All patients were followed up and patients were accomplished with total active motion(TAM)of fingers.Results All patients were reviewed by an independent observer.The mean follow up was 13 months(range 9 to 24 months).Subjective,objective and radiographic results were evaluated.X-ray films revealed fracture union and the average radiographic union time was 7 weeks with a range of 5-12 weeks and the phalange shortening or rotation in 2 cases,joint incongruity(less than 1 mm)and joint space narrowing in 3 cases respectively.Phalangeal shortening or rotation was observed in 2 cases and joint incongruity or joint space narrowing was observed in 3 cases.An artificial implant was performed on one case for traumatic arthritis 1.5 years after surgery.Based on TAM the overall good-excellent rate of joint motion function was 80.8%.Conclusion Mini external fixator combined with limited internal fixation is a reliable and effective method for treatment of intra-articular fracture of the fingers.

  6. Interferometer readout-noise below the Standard Quantum Limit of a membrane

    CERN Document Server

    Westphal, Tobias; Kaufer, Henning; Yamamoto, Kazuhiro; Gossler, Stefan; Mueller-Ebhardt, Helge; Danilishin, Stefan L; Khalili, Farid Ya; Danzmann, Karsten; Schnabel, Roman

    2011-01-01

    Here we report on the realization of a Michelson-Sagnac interferometer whose purpose is the precise characterization of the motion of membranes showing significant light transmission. Our interferometer has a readout noise spectral density (imprecision) of 3E-16 m/sqrt(Hz) at frequencies around the fundamental resonance of a SiN_x membrane at about 100 kHz, without using optical cavities. The readout noise demonstrated is more than 16 dB below the peak value of the membrane's standard quantum limit (SQL). This reduction is significantly higher than those of previous works with nano-wires [Teufel et al., Nature Nano. 4, 820 (2009); Anetsberger et al., Nature Phys. 5, 909 (2009)]. We discuss the meaning of the SQL for force measurements and its relation to the readout performance and conclude that neither our nor previous experiments achieved a total noise spectral density as low as the SQL.

  7. Identification of macrophage external membrane proteins and their possible role in cell adhesion.

    Science.gov (United States)

    Pearlstein, E; Dienstman, S R; Defendi, V

    1978-10-01

    Starch-activated mouse peritoneal macrophages (STpMAC) plated on plastic demonstrate the adhesive properties typical for activated pMAC: attaching as round cells and, within 15 min, spreading out with marginal membrane ruffles. These attached STpMAC were labeled by lactoperoxidase-catalysed 125I surface iodination, sodium dodecyl-sulfate-lysed, and the lysates electrophoresed on polyacrylamide gels which were examined by autoradiography. The STpMAC morphological phenotype correlates with the labeling of a particular protein (195,000, estimated mol wt). Normal pMAC (NpMAC), from unstimulated mice, do not spread and do not display the 195,000 band. Both pMAC band patterns, including the 195,000 band, are relatively resistant to trypsin digestion, as is pMAC adhesion itself trypsin-resistant. Neither class of pMAC exhibits fibronectin (Cell Adhesion Factor, LETS protein) which is a component in the adhesive matrix of cells forming trypsin-sensitive monolayers. When pMAC are tested against antifibronectin antibody, these cells do not give immunofluorescent staining. In summary, two functions in pMAC adhesion, enzyme resistance and the ability to spread, appear related to molecular properties distinctive for pMAC surface protein.

  8. Externally Phase-Locked Flux Flow Oscillator for Submm Integrated Receivers; Achievements and Limitations

    DEFF Research Database (Denmark)

    Koshelets, V. P.; Shitov, S. V.; Dmitriev, P. N.

    2003-01-01

    to 712 GHz, limited only by the gap frequency of Nb. This enabled us to phase lock the FFO in the frequency range 500-712 GHz where continuous frequency tuning is possible; resulting in an absolute FFO phase noise as low as -80 dBc at 707 GHz. Comprehensive measurements of the FFO radiation linewidth...

  9. Renormalization and Central limit theorem for critical dynamical systems with weak external noise

    CERN Document Server

    Diaz-Espinosa, O

    2006-01-01

    We study of the effect of weak noise on critical one dimensional maps; that is, maps with a renormalization theory. We establish a one dimensional central limit theorem for weak noises and obtain Berry--Esseen estimates for the rate of this convergence. We analyze in detail maps at the accumulation of period doubling and critical circle maps with golden mean rotation number. Using renormalization group methods, we derive scaling relations for several features of the effective noise after long times. We use these scaling relations to show that the central limit theorem for weak noise holds in both examples. We note that, for the results presented here, it is essential that the maps have parabolic behavior. They are false for hyperbolic orbits.

  10. Nef decreases HIV-1 sensitivity to neutralizing antibodies that target the membrane-proximal external region of TMgp41.

    Directory of Open Access Journals (Sweden)

    Rachel P J Lai

    2011-12-01

    Full Text Available Primate lentivirus nef is required for sustained virus replication in vivo and accelerated progression to AIDS. While exploring the mechanism by which Nef increases the infectivity of cell-free virions, we investigated a functional link between Nef and Env. Since we failed to detect an effect of Nef on the quantity of virion-associated Env, we searched for qualitative changes by examining whether Nef alters HIV-1 sensitivity to agents that target distinct features of Env. Nef conferred as much as 50-fold resistance to 2F5 and 4E10, two potent neutralizing monoclonal antibodies (nAbs that target the membrane proximal external region (MPER of TMgp41. In contrast, Nef had no effect on HIV-1 neutralization by MPER-specific nAb Z13e1, by the peptide inhibitor T20, nor by a panel of nAbs and other reagents targeting gp120. Resistance to neutralization by 2F5 and 4E10 was observed with Nef from a diverse range of HIV-1 and SIV isolates, as well as with HIV-1 virions bearing Env from CCR5- and CXCR4-tropic viruses, clade B and C viruses, or primary isolates. Functional analysis of a panel of Nef mutants revealed that this activity requires Nef myristoylation but that it is genetically separable from other Nef functions such as the ability to enhance virus infectivity and to downregulate CD4. Glycosylated-Gag from MoMLV substituted for Nef in conferring resistance to 2F5 and 4E10, indicating that this activity is conserved in a retrovirus that does not encode Nef. Given the reported membrane-dependence of MPER-recognition by 2F5 and 4E10, in contrast to the membrane-independence of Z13e1, the data here is consistent with a model in which Nef alters MPER recognition in the context of the virion membrane. Indeed, Nef and Glycosylated-Gag decreased the efficiency of virion capture by 2F5 and 4E10, but not by other nAbs. These studies demonstrate that Nef protects lentiviruses from one of the most broadly-acting classes of neutralizing antibodies. This newly

  11. Externally Phase-Locked Flux Flow Oscillator for Submm Integrated Receivers; Achievements and Limitations

    DEFF Research Database (Denmark)

    Koshelets, V. P.; Shitov, S. V.; Dmitriev, P. N.;

    2003-01-01

    to 712 GHz, limited only by the gap frequency of Nb. This enabled us to phase lock the FFO in the frequency range 500-712 GHz where continuous frequency tuning is possible; resulting in an absolute FFO phase noise as low as -80 dBc at 707 GHz. Comprehensive measurements of the FFO radiation linewidth...... have been performed using an integrated SIS harmonic mixer. The influence of FFO parameters on radiation linewidth, particularly the effect of the differential resistances associated both with the bias current and the applied magnetic field has been studied in order to further optimize the FFO design....... A new approach with a self-shielded FFO has been developed and experimentally tested....

  12. Macular Hole Surgery with Internal Limiting Membrane Peeling Facilitated by Membrane-Blue® versus Membrane-Blue-Dual®: A Retrospective Comparative Study

    Science.gov (United States)

    Shai, Daniel; Loewenstein, Anat

    2016-01-01

    Background. This study aims to compare the outcome of macular hole (MH) surgery with internal limiting membrane (ILM) peeling facilitated by two different vital dyes. Methods. This was a retrospective chart review. The group designated “group-MB” underwent pars plana vitrectomy with ILM peeling facilitated by Membrane-Blue (MB), whereas in “group-MBD,” the vital dye used was Membrane-Blue-Dual (MBD). Results. Seventy-four eyes comprised the study population: 53 in group-MB and 21 in group-MBD. There was no difference in the rate of macular hole closure in group-MB or group-MBD: 71.2% closed MHs compared to 66.7%, respectively (p = 0.7). Postoperative visual improvement was of a higher magnitude in the MBD group compared to the MB group: −0.34 ± 0.81 logMAR versus 0.01 ± 0.06 logMAR, respectively (p = 0.003). Conclusions. In this study, MBD led to better visual results that may be related to better staining characteristics or lesser toxicity compared to MB. PMID:28050275

  13. Laser cooling of a micromechanical membrane to the quantum backaction limit

    CERN Document Server

    Peterson, R W; Kampel, N S; Andrews, R W; Yu, P -L; Lehnert, K W; Regal, C A

    2015-01-01

    The radiation pressure of light can act to damp and cool the vibrational motion of a mechanical resonator. In understanding the quantum limits of this cooling, one must consider the effect of shot noise fluctuations on the final thermal occupation. In optomechanical sideband cooling in a cavity, the finite Stokes Raman scattering defined by the cavity linewidth combined with shot noise fluctuations dictates a quantum backaction limit, analogous to the Doppler limit of atomic laser cooling. In our work we sideband cool to the quantum backaction limit by using a micromechanical membrane precooled in a dilution refrigerator. Monitoring the optical sidebands allows us to directly observe the mechanical object come to thermal equilibrium with the optical bath.

  14. Laser Cooling of a Micromechanical Membrane to the Quantum Backaction Limit.

    Science.gov (United States)

    Peterson, R W; Purdy, T P; Kampel, N S; Andrews, R W; Yu, P-L; Lehnert, K W; Regal, C A

    2016-02-12

    The radiation pressure of light can act to damp and cool the vibrational motion of a mechanical resonator, but even if the light field has no thermal component, shot noise still sets a limit on the minimum phonon occupation. In optomechanical sideband cooling in a cavity, the finite off-resonant Stokes scattering defined by the cavity linewidth combined with shot noise fluctuations dictates a quantum backaction limit, analogous to the Doppler limit of atomic laser cooling. In our work, we sideband cool a micromechanical membrane resonator to the quantum backaction limit. Monitoring the optical sidebands allows us to directly observe the mechanical object come to thermal equilibrium with the optical bath. This level of optomechanical coupling that overwhelms the intrinsic thermal decoherence was not reached in previous ground-state cooling demonstrations.

  15. Progress on Background-Limited Membrane-Isolated TES Bolometers for Far-IR/Submillimeter Spectroscopy

    Science.gov (United States)

    Kenyon, M.; Day, P. K.; Bradford, C. M.; Bock, J. J.; Leduc, H. G.

    2006-01-01

    To determine the lowest attainable phonon noise equivalent power (NEP) for membrane-isolation bolometers, we fabricated and measured the thermal conductance of suspended Si3N4 beams with different geometries via a noise thermometry technique. We measured beam cross-sectional areas ranging from 0.35 x 0.5 (micro)m(sup 2) to 135 x 1.0 (micro)m(sup 2) and beam lengths ranging from (micro)m to 8300 (micro)m. The measurements directly imply that membrane-isolation bolometers are capable of reaching a phonon noise equivalent power (NEP) of 4 x 10(sup -20)W/Hz(sup 1)/O . This NEP adequate for the Background-Limited Infrared-Submillimeter Spectrograph (BLISS) proposed for the Japanese SPICA observatory, and adequate for NASA's SAFIR observatory, a 10-meter, 4 K telescope to be deployed at L2. Further, we measured the heat capacity of a suspended Si3N4 membrane and show how this result implies that one can make membrane-isolation bolometers with a response time which is fast enough for BLISS.

  16. Radial phononic thermal conductance in thin membranes in the Casimir limit: Design guidelines for devices

    Science.gov (United States)

    Puurtinen, T. A.; Maasilta, I. J.

    2014-12-01

    In a previous publication [I. J. Maasilta, AIP Advances 1, 041704 (2011)], we discussed the formalism and some computational results for phononic thermal conduction in the suspended membrane geometry for radial heat flow from a central source, which is a common geometry for some low-temperature detectors, for example. We studied the case where only diffusive surface scattering is present, the so called Casimir limit, which can be experimentally relevant at temperatures below ˜ 10 K in typical materials, and even higher for ultrathin samples. Here, we extend our studies to much thinner membranes, obtaining numerical results for geometries which are more typical in experiments. In addition, we interpret the results in terms of the small signal and differential thermal conductance, so that guidelines for designing devices, such as low-temperature bolometric detectors, are more easily obtained. Scaling with membrane dimensions is shown to differ significantly from the bulk scattering, and, in particular, thinning the membrane is shown to lead to a much stronger reduction in thermal conductance than what one would envision from the simplest bulk formulas.

  17. Radial phononic thermal conductance in thin membranes in the Casimir limit: Design guidelines for devices

    Directory of Open Access Journals (Sweden)

    T. A. Puurtinen

    2014-12-01

    Full Text Available In a previous publication [I. J. Maasilta, AIP Advances 1, 041704 (2011], we discussed the formalism and some computational results for phononic thermal conduction in the suspended membrane geometry for radial heat flow from a central source, which is a common geometry for some low-temperature detectors, for example. We studied the case where only diffusive surface scattering is present, the so called Casimir limit, which can be experimentally relevant at temperatures below ∼ 10 K in typical materials, and even higher for ultrathin samples. Here, we extend our studies to much thinner membranes, obtaining numerical results for geometries which are more typical in experiments. In addition, we interpret the results in terms of the small signal and differential thermal conductance, so that guidelines for designing devices, such as low-temperature bolometric detectors, are more easily obtained. Scaling with membrane dimensions is shown to differ significantly from the bulk scattering, and, in particular, thinning the membrane is shown to lead to a much stronger reduction in thermal conductance than what one would envision from the simplest bulk formulas.

  18. 4E10-resistant HIV-1 isolated from four subjects with rare membrane-proximal external region polymorphisms.

    Directory of Open Access Journals (Sweden)

    Kyle J Nakamura

    Full Text Available Human antibody 4E10 targets the highly conserved membrane-proximal external region (MPER of the HIV-1 transmembrane glycoprotein, gp41, and has extraordinarily broad neutralizing activity. It is considered by many to be a prototype for vaccine development. In this study, we describe four subjects infected with viruses carrying rare MPER polymorphisms associated with resistance to 4E10 neutralization. In one case resistant virus carrying a W680G substitution was transmitted from mother to infant. We used site-directed mutagenesis to demonstrate that the W680G substitution is necessary for conferring the 4E10-resistant phenotype, but that it is not sufficient to transfer the phenotype to a 4E10-sensitive Env. Our third subject carried Envs with a W680R substitution causing variable resistance to 4E10, indicating that residues outside the MPER are required to confer the phenotype. A fourth subject possessed a F673L substitution previously associated with 4E10 resistance. For all three subjects with W680 polymorphisms, we observed additional residues in the MPER that co-varied with position 680 and preserved charged distributions across this region. Our data provide important caveats for vaccine development targeting the MPER. Naturally occurring Env variants described in our study also represent unique tools for probing the structure-function of HIV-1 envelope.

  19. Comparative kinetics of damage to the plasma and mitochondrial membranes by intra-cellularly synthesized and externally-provided photosensitizers using multi-color FACS.

    Science.gov (United States)

    Haupt, Sara; Malik, Zvi; Ehrenberg, Benjamin

    2014-01-01

    Photodynamic therapy (PDT) of cancer involves inflicting lethal damage to the cells of malignant tumors, primarily by singlet oxygen that is generated following light-absorption in a photosensitizer molecule. Dysfunction of cells is manifested in many ways, including peroxidation of cellular components, membrane rupture, depolarization of electric potentials, termination of mitochondrial activity, onset of apoptosis and necrosis and eventually cell lysis. These events do not necessarily occur in linear fashion and different types of damage to cell components occur, most probably, in parallel. In this report we measured the relative rates of damage to two cellular membranes: the plasma membrane and the mitochondrial membrane. We employed photosensitizers of diverse hydrophobicities and used different incubation procedures, which lead to their different intra-cellular localizations. We monitored the damage that was inflicted on these membranes, by employing optical probes of membrane integrity, in a multi-color FACS experiment. The potentiometric indicator JC-1 monitored the electric cross-membrane potential of the mitochondria and the fluorometric indicator Draq7 monitored the rupture of the plasma membrane. We show that the electric depolarization of the mitochondrial membrane and the damage to the enveloping plasma membrane proceed with different kinetics that reflect the molecular character and intracellular location of the sensitizer: PpIX that is synthesized in the cells from ALA causes rapid mitochondrial damage and very slow damage to the plasma membrane, while externally added PpIX has an opposite effect. The hydrophilic sensitizer HypS4 can be taken up by the cells by different incubation conditions, and these affect its intracellular location, and as a consequence either the plasma membrane or the mitochondria is damaged first. A similar correlation was found for additional extracellularly-provided photosensitizers HP and PpIX.

  20. Stability Limit of Water by Metastable Vapor-Liquid Equilibrium with Nanoporous Silicon Membranes.

    Science.gov (United States)

    Chen, I-Tzu; Sessoms, David A; Sherman, Zachary; Choi, Eugene; Vincent, Olivier; Stroock, Abraham D

    2016-06-16

    Liquid can sustain mechanical tension as its pressure drops below the vapor-liquid coexistence line and becomes less than zero, until it reaches the stability limit-the pressure at which cavitation inevitably occurs. For liquid water, its stability limit is still a subject of debate: the results obtained by researchers using a variety of techniques show discrepancies between the values of the stability limit and its temperature dependence as temperature approaches 0 °C. In this work, we present a study of the stability limit of water by the metastable vapor-liquid equilibrium (MVLE) method with nanoporous silicon membranes. We also report on an experimental system which enables tests of the temperature dependence of the stability limit with MVLE. The stability limit we found increases monotonically (larger tension) as temperature approaches 0 °C; this trend contradicts the centrifugal result of Briggs but agrees with the experiments by acoustic cavitation. This result confirms that a quasi-static method can reach stability values similar to that from the dynamic stretching technique, even close to 0 °C. Nevertheless, our results fall in the range of ∼ -20 to -30 MPa, a range that is consistent with the majority of experiments but is far less negative than the limit obtained in experiments involving quartz inclusions and that predicted for homogeneous nucleation.

  1. Highly-efficient, diffraction-limited laser emission from a Vertical External Cavity Surface-emitting Organic Laser

    CERN Document Server

    Rabbani-Haghighi, Hadi; Chenais, Sebastien; Siove, Alain

    2010-01-01

    We report on a solid-state laser structure being the organic counterpart of the Vertical External-Cavity Surface-Emitting Laser (VECSEL) design. The gain medium is a poly (methyl methacrylate) film doped with Rhodamine 640, spin-casted onto the High-Reflectivity mirror of a plano-concave resonator. Upon pumping by 7-ns pulses at 532 nm, a diffraction-limited beam (M^2=1) was obtained, with a conversion efficiency of 43%; higher peak powers (2kW) could be attained when resorting to shorter (0.5 ns) pump pulses. The spectrum was controlled by the thickness of the active layer playing the role of an intracavity etalon; tunability is demonstrated over up to 20 nm.

  2. Rotating electrode potentiometry: lowering the detection limits of nonequilibrium polyion-sensitive membrane electrodes.

    Science.gov (United States)

    Ye, Q; Meyerhoff, M E

    2001-01-15

    A rotating electrode configuration is evaluated as a means to lower the detection limits of newly devised polyion-sensitive membrane electrodes (PSEs). Planar potentiometric polycation and polyanion PSEs are prepared by incorporating tridodecylmethylammonium chloride and calcium dinonylnaphthalenesulfonate, respectively, into plasticized PVC or polyurethane membranes and mounting disks of such films on an electrode body housed in a conventional rotating disk electrode apparatus. Rotation of the PSEs at 5000 rpm results in an enhancement in the detection limits toward heparin (polyanion) and protamine (polycation) of at least 1 order of magnitude (to 0.01 unit/mL for heparin; 0.02 microg/mL for protamine) over that observed when the EMF responses of the same electrodes are assessed using a stir-bar to achieve convective mass transport. A linear relationship between omega(-1/2), where omega is the rotating angular frequency, and C1/2, the polyion concentration corresponding to half the total maximum deltaEMF response toward the polyion species, is observed. It is further shown that the rotating polycation sensor can be used as an end-point detector to greatly enhance (relative to nonrotated indicator electrode) the analytical resolution and precision for measurement of low concentrations of heparin when such samples are titrated with protamine. The theoretical basis for lowering the detection limits by rotating PSEs is discussed based on the unique nonequilibrium response mechanism of such sensors.

  3. Surgical outcomes of inverted internal limiting membrane flap technique for large macular hole

    Directory of Open Access Journals (Sweden)

    Prabhushanker Mahalingam

    2013-01-01

    Full Text Available We are presenting the initial results of inverted internal limiting membrane (ILM flap technique for large macular hole. Five eyes of five patients with large diameter macular hole (>700 μm were selected. All patients underwent inverted ILM flap technique for macular hole. Anatomical closure and functional success were achieved in all patients. There was no loss of best-corrected visual acuity in any of the patients. Inverted ILM flap technique in macular hole surgery seems to have a better hole closure rates, especially in large diameter macular holes. Larger case series is required to assess the efficacy and safety of this technique.

  4. Use of Internal Limiting Membrane Autograft in Primary Vitrectomy for Rhegmatogenous Retinal Detachment

    Directory of Open Access Journals (Sweden)

    Sergio Eustolio Hernández-Da Mota

    2016-11-01

    Full Text Available During a pars plana vitrectomy, an unplanned retinotomy in the raphe was performed in a 55-year-old female patient with rhegmatogenous retinal detachment and proliferative vitreoretinopathy. Since diathermy and laser therapy were not available at that moment, it was decided to peel off a small graft of the internal limiting membrane adjacent to the retinotomy site which had been previously stained with Brilliant Blue G. The graft was displaced under perfluorocarbon fluids and placed inside the retinotomy. Three weeks after surgery, the apparent closure of the retinotomy was observed clinically.

  5. Vitrectomy with Internal Limiting Membrane Peeling versus No Peeling for Idiopathic Full-Thickness Macular Hole

    DEFF Research Database (Denmark)

    Spiteri Cornish, Kurt; Lois, Noemi; Scott, Neil W

    2014-01-01

    OBJECTIVE: To determine whether internal limiting membrane (ILM) peeling improves anatomic and functional outcomes of full-thickness macular hole (FTMH) surgery when compared with the no-peeling technique. DESIGN: Systematic review and individual participant data (IPD) meta-analysis undertaken...... under the auspices of the Cochrane Eyes and Vision Group. Only randomized controlled trials (RCTs) were included. PARTICIPANTS AND CONTROLS: Patients with idiopathic stage 2, 3, and 4 FTMH undergoing vitrectomy with or without ILM peeling. INTERVENTION: Macular hole surgery, including vitrectomy and gas...

  6. Lipid engineering reveals regulatory roles for membrane fluidity in yeast flocculation and oxygen-limited growth

    Energy Technology Data Exchange (ETDEWEB)

    Degreif, Daniel [Joint BioEnergy Inst. (JBEI), Emeryville, CA (United States); Technical Univ. of Darmstadt (Germany); de Rond, Tristan [Joint BioEnergy Inst. (JBEI), Emeryville, CA (United States); Univ. of California, Berkeley, CA (United States); Bertl, Adam [Technical Univ. of Darmstadt (Germany); Keasling, Jay D. [Joint BioEnergy Inst. (JBEI), Emeryville, CA (United States); Univ. of California, Berkeley, CA (United States); Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Technical Univ. of Denmark, Lyngby (Denmark); Budin, Itay [Joint BioEnergy Inst. (JBEI), Emeryville, CA (United States); Univ. of California, Berkeley, CA (United States)

    2017-03-18

    Cells modulate lipid metabolism in order to maintain membrane homeostasis. In this paper, we use a metabolic engineering approach to manipulate the stoichiometry of fatty acid unsaturation, a regulator of cell membrane fluidity, in Saccharomyces cerevisiae. Unexpectedly, reduced lipid unsaturation triggered cell-cell adhesion (flocculation), a phenomenon characteristic of industrial yeast but uncommon in laboratory strains. We find that ER lipid saturation sensors induce expression of FLO1 – encoding a cell wall polysaccharide binding protein – independently of its canonical regulator. In wild-type cells, Flo1p-dependent flocculation occurs under oxygen-limited growth, which reduces unsaturated lipid synthesis and thus serves as the environmental trigger for flocculation. Transcriptional analysis shows that FLO1 is one of the most highly induced genes in response to changes in lipid unsaturation, and that the set of membrane fluidity-sensitive genes is globally activated as part of the cell's long-term response to hypoxia during fermentation. Finally, our results show how the lipid homeostasis machinery of budding yeast is adapted to carry out a broad response to an environmental stimulus important in biotechnology.

  7. Histopathologic and Electron Microscopic Features of Internal Limiting Membranes in Maculopathies of Various Etiologies

    Directory of Open Access Journals (Sweden)

    Mozhgan Rezaei Kanavi

    2014-01-01

    Full Text Available Purpose: To report micro- and ultrastructural features of internal limiting membranes (ILMs in various maculopathies and to evaluate the effects of indocyanine green (ICG and triamcinolone acetonide (TA on epiretinal proliferations associated with ILM and on retinal cleavage plane. Methods: ILMs from various maculopathies were evaluated regarding presence or absence of membrane-associated cells, type of cells and ILM thickness based on routine histopathology, immunohistochemistry and transmission electron microscopy (TEM. Results: Thirty ILM specimens were enrolled; 25 of which were evaluated by histopathology and immunohistochemistry and 5 by TEM. ICG only had been used in 17 specimens, TA in 4, and both agents in one specimen. The majority of specimens were immunoreactive for glial fibrillary acidic protein and neuron specific enolase. No significant difference in specimen cellularity and alteration of cleavage plane was noted between ICG-stained and non-ICG-stained ILMs or between TA-assisted and non-TAassisted ones. Excluding central retinal vein occlusion (CRVO cases, acellularity was not observed in any of ILMs from diabetic macular edema (DME, cystoid macular edema (CME, and traumatic macular hole (TMH eyes. TEM disclosed ILM thickening and cellularity in DME as compared to CRVO. Conclusion: Acellular membranes from CRVO maculopathy may be a sequel of acute retinal ischemia. Thickened diabetic ILMs with high cellularity may be related to chronic activation of Muller cells. No obvious influence of ICG or TA on epiretinal cellularity was detected and the dyes seem to have no significant effect on cleavage plane.

  8. Modulating immunogenic properties of HIV-1 gp41 membrane-proximal external region by destabilizing six-helix bundle structure

    Energy Technology Data Exchange (ETDEWEB)

    Banerjee, Saikat; Shi, Heliang; Habte, Habtom H.; Qin, Yali; Cho, Michael W., E-mail: mcho@iastate.edu

    2016-03-15

    The C-terminal alpha-helix of gp41 membrane-proximal external region (MPER; {sup 671}NWFDITNWLWYIK{sup 683}) encompassing 4E10/10E8 epitopes is an attractive target for HIV-1 vaccine development. We previously reported that gp41-HR1-54Q, a trimeric protein comprised of the MPER in the context of a stable six-helix bundle (6HB), induced strong immune responses against the helix, but antibodies were directed primarily against the non-neutralizing face of the helix. To better target 4E10/10E8 epitopes, we generated four putative fusion intermediates by introducing double point mutations or deletions in the heptad repeat region 1 (HR1) that destabilize 6HB in varying degrees. One variant, HR1-∆10-54K, elicited antibodies in rabbits that targeted W672, I675 and L679, which are critical for 4E10/10E8 recognition. Overall, the results demonstrated that altering structural parameters of 6HB can influence immunogenic properties of the MPER and antibody targeting. Further exploration of this strategy could allow development of immunogens that could lead to induction of 4E10/10E8-like antibodies. - Highlights: • Four gp41 MPER-based immunogens that resemble fusion intermediates were generated. • C-terminal region of MPER that contains 4E10/10E8 epitopes was highly immunogenic. • Altering 6HB structure can influence immunogenic properties of the MPER. • Induced antibodies targeted multiple residues critical for 4E10/10E8 binding. • Development of immunogens based on fusion intermediates is a promising strategy.

  9. Mutations in Lama1 disrupt retinal vascular development and inner limiting membrane formation.

    Science.gov (United States)

    Edwards, Malia M; Mammadova-Bach, Elmina; Alpy, Fabien; Klein, Annick; Hicks, Wanda L; Roux, Michel; Simon-Assmann, Patricia; Smith, Richard S; Orend, Gertraud; Wu, Jiang; Peachey, Neal S; Naggert, Jürgen K; Lefebvre, Olivier; Nishina, Patsy M

    2010-03-05

    The Neuromutagenesis Facility at the Jackson Laboratory generated a mouse model of retinal vasculopathy, nmf223, which is characterized clinically by vitreal fibroplasia and vessel tortuosity. nmf223 homozygotes also have reduced electroretinogram responses, which are coupled histologically with a thinning of the inner nuclear layer. The nmf223 locus was mapped to chromosome 17, and a missense mutation was identified in Lama1 that leads to the substitution of cysteine for a tyrosine at amino acid 265 of laminin alpha1, a basement membrane protein. Despite normal localization of laminin alpha1 and other components of the inner limiting membrane, a reduced integrity of this structure was suggested by ectopic cells and blood vessels within the vitreous. Immunohistochemical characterization of nmf223 homozygous retinas demonstrated the abnormal migration of retinal astrocytes into the vitreous along with the persistence of hyaloid vasculature. The Y265C mutation significantly reduced laminin N-terminal domain (LN) interactions in a bacterial two-hybrid system. Therefore, this mutation could affect interactions between laminin alpha1 and other laminin chains. To expand upon these findings, a Lama1 null mutant, Lama1(tm1.1Olf), was generated that exhibits a similar but more severe retinal phenotype than that seen in nmf223 homozygotes. The increased severity of the Lama1 null mutant phenotype is probably due to the complete loss of the inner limiting membrane in these mice. This first report of viable Lama1 mouse mutants emphasizes the importance of this gene in retinal development. The data presented herein suggest that hypomorphic mutations in human LAMA1 could lead to retinal disease.

  10. Early and late inner retinal changes after inner limiting membrane peeling.

    Science.gov (United States)

    Pichi, Francesco; Lembo, Andrea; Morara, Mariachiara; Veronese, Chiara; Alkabes, Micol; Nucci, Paolo; Ciardella, Antonio P

    2014-04-01

    Pars plana vitrectomy and inner limiting membrane (ILM) peeling are standard procedures for macular hole and epiretinal membrane surgery. However, ILM peeling is known to cause mechanical traumatic changes to the retinal nerve fiber layer. Recently there have been numerous reports of anatomical changes in the macula after ILM removal. A comprehensive review of the literature. The earliest change in the macula after ILM peeling is post-operative swelling of the arcuate retinal nerve fiber layer (SANFL), which disappears within the 3 month; the swelling is not detected on biomicroscopic fundus examination but appears as hypoautofluorescent arcuate striae in the macular region on infrared and autofluorescence imaging, with corresponding hyperreflectant swelling demonstrated on spectral-domain optical coherence tomography (OCT). SANFL is followed by dissociated optic nerve fiber layer defect, faintly visible on fundus examination and corresponding on OCT to "dimples" in the inner retinal layers. The en face tomographic aspect of this defect appears as concentric macular dark spots. Post-operative foveal displacement toward the optic disc might be responsible for the stretching and thinning of the retinal parenchyma in the temporal subfield and the thickening of the nasal macula. This shortening of the papillofoveal distance after surgery is probably secondary to axonal transport and contractility alterations in the nerve fiber layer, which might also account for apoptotic and atrophic degeneration of the peripapillary retinal nerve fiber layer. Ganglion cells do not seem to be affected by ILM peeling, even if the ganglion cell complex loses some volume because of trauma to the Müller cells contained in the ganglion cell layer. Despite its clear indication in macular hole and epiretinal membrane surgery, ILM peeling is a traumatic procedure that has acute effects on the underlying inner retinal layers. Further investigation of these subclinical changes may assist in

  11. Testing the limits of rational design by engineering pH sensitivity into membrane active peptides

    Science.gov (United States)

    Wiedman, Gregory

    2015-01-01

    In this work, we sought to rationally design membrane active peptides that are triggered by low pH to form macromolecular-sized pores in lipid bilayers. Such peptides could have broad utility in biotechnology and in nanomedicine as cancer therapeutics or drug delivery vehicles that promote release of macromolecules from endosomes. Our approach to rational design was to combine the properties of a pH-independent peptide, MelP5, which forms large pores allowing passage of macromolecules, with the properties of two pH-dependent membrane active peptides, pHlip and GALA. We created two hybrid sequences, MelP5_Δ4 and MelP5_Δ6 by using the distribution of acidic residues on pHlip and GALA as a guide to insert acidic amino acids into the amphipathic helix of MelP5. We show that the new peptides bind to lipid bilayers and acquire secondary structure in a pH-dependent manner. The peptides also destabilize bilayers in a pH-dependent manner, such that lipid vesicles release the small molecules ANTS/DPX at low pH only. Thus, we were successful in designing pH-triggered pore-forming peptides. However, no macro-molecular release was observed under any conditions. Therefore, we abolished the unique macromolecular poration properties of MelP5 by introducing pH-sensitivity into its sequence. We conclude that the properties of pHlip, GALA and MelP5 are additive, but only partially so. We propose that this lack of additivity is a limitation in the rational design of novel membrane active peptides, and that high-throughput approaches to discovery will be critical for continued progress in the field. PMID:25572997

  12. Experimental Investigation and Discussion on the Mechanical Endurance Limit of Nafion Membrane Used in Proton Exchange Membrane Fuel Cell

    Directory of Open Access Journals (Sweden)

    Yang Xiao

    2014-10-01

    Full Text Available As a solution of high efficiency and clean energy, fuel cell technologies, especially proton exchange membrane fuel cell (PEMFC, have caught extensive attention. However, after decades of development, the performances of PEMFCs are far from achieving the target from the Department of Energy (DOE. Thus, further understanding of the degradation mechanism is needed to overcome this obstacle. Due to the importance of proton exchange membrane in a PEMFC, the degradation of the membrane, such as hygrothermal aging effect on its properties, are particularly necessary. In this work, a thick membrane (Nafion N117, which is always used as an ionic polymer for the PEMFCs, has been analyzed. Experimental investigation is performed for understanding the mechanical endurance of the bare membranes under different loading conditions. Tensile tests are conducted to compare the mechanical property evolution of two kinds of bare-membrane specimens including the dog-bone and the deeply double edge notched (DDEN types. Both dog-bone and DDEN specimens were subjected to a series of degradation tests with different cycling times and wide humidity ranges. The tensile tests are repeated for both kinds of specimens to assess the strain-stress relations. Furthermore, Fourier transform infrared spectroscopy (FT-IR, X-ray diffraction (XRD and Scanning electron microscope (SEM observation and water absorption measurement were conducted to speculate the cause of this variation. The initial cracks along with the increasing of bound water content were speculated as the primary cause.

  13. Enhancements and limits in drug membrane transport using supersaturated solutions of poorly water soluble drugs.

    Science.gov (United States)

    Raina, Shweta A; Zhang, Geoff G Z; Alonzo, David E; Wu, Jianwei; Zhu, Donghua; Catron, Nathaniel D; Gao, Yi; Taylor, Lynne S

    2014-09-01

    Amorphous solid dispersions (ASDs) give rise to supersaturated solutions (solution concentration greater than equilibrium crystalline solubility). We have recently found that supersaturating dosage forms can exhibit the phenomenon of liquid-liquid phase separation (LLPS). Thus, the high supersaturation generated by dissolving ASDs can lead to a two-phase system wherein one phase is an initially nanodimensioned and drug-rich phase and the other is a drug-lean continuous aqueous phase. Herein, the membrane transport of supersaturated solutions, at concentrations above and below the LLPS concentration has been evaluated using a side-by-side diffusion cell. Measurements of solution concentration with time in the receiver cell yield the flux, which reflects the solute thermodynamic activity in the donor cell. As the nominal concentration of solute in the donor cell increases, a linear increase in flux was observed up to the concentration where LLPS occurred. Thereafter, the flux remained essentially constant. Both nifedipine and felodipine solutions exhibit such behavior as long as crystallization is absent. This suggests that there is an upper limit in passive membrane transport that is dictated by the LLPS concentration. These results have several important implications for drug delivery, especially for poorly soluble compounds requiring enabling formulation technologies.

  14. Engineering Recombinant Reoviruses To Display gp41 Membrane-Proximal External-Region Epitopes from HIV-1

    Science.gov (United States)

    Boehme, Karl W.; Ikizler, Mine'; Iskarpatyoti, Jason A.; Wetzel, J. Denise; Willis, Jordan; Crowe, James E.; LaBranche, Celia C.; Montefiori, David C.

    2016-01-01

    ABSTRACT The gp41 membrane-proximal external region (MPER) is a target for broadly neutralizing antibody responses against human immunodeficiency virus type 1 (HIV-1). However, replication-defective virus vaccines currently under evaluation in clinical trials do not efficiently elicit MPER-specific antibodies. Structural modeling suggests that the MPER forms an α-helical coiled coil that is required for function and immunogenicity. To maintain the native MPER conformation, we used reverse genetics to engineer replication-competent reovirus vectors that displayed MPER sequences in the α-helical coiled-coil tail domain of viral attachment protein σ1. Sequences in reovirus strain type 1 Lang (T1L) σ1 were exchanged with sequences encoding HIV-1 strain Ba-L MPER epitope 2F5 or the entire MPER. Individual 2F5 or MPER substitutions were introduced at virion-proximal or virion-distal sites in the σ1 tail. Recombinant reoviruses containing heterologous HIV-1 sequences were viable and produced progeny yields comparable to those with wild-type virus. HIV-1 sequences were retained following 10 serial passages in cell culture, indicating that the substitutions were genetically stable. Recombinant viruses engineered to display the 2F5 epitope or full-length MPER in σ1 were recognized by purified 2F5 antibody. Inoculation of mice with 2F5-containing vectors or rabbits with 2F5- or MPER-containing vectors elicited anti-reovirus antibodies, but HIV-1-specific antibodies were not detected. Together, these findings indicate that heterologous sequences that form α-helices can functionally replace native sequences in the α-helical tail domain of reovirus attachment protein σ1. However, although these vectors retain native antigenicity, they were not immunogenic, illustrating the difficulty of experimentally inducing immune responses to this essential region of HIV-1. IMPORTANCE Vaccines to protect against HIV-1, the causative agent of AIDS, are not approved for use

  15. Membraner

    DEFF Research Database (Denmark)

    Bach, Finn

    2009-01-01

    Notatet giver en kort introduktion til den statiske virkemåde af membraner og membrankonstruktioner......Notatet giver en kort introduktion til den statiske virkemåde af membraner og membrankonstruktioner...

  16. Surface oxygen vacancy and oxygen permeation flux limits of perovskite ion transport membranes

    KAUST Repository

    Hunt, Anton

    2015-09-01

    © 2015 Elsevier B.V. The mechanisms and quantitative models for how oxygen is separated from air using ion transport membranes (ITMs) are not well understood, largely due to the experimental complexity for determining surface exchange reactions at extreme temperatures (>800°C). This is especially true when fuels are present at the permeate surface. For both inert and reactive (fuels) operations, solid-state oxygen surface vacancies (δ) are ultimately responsible for driving the oxygen flux, JO2. In the inert case, the value of δ at either surface is a function of the local PO2 and temperature, whilst the magnitude of δ dictates both the JO2 and the inherent stability of the material. In this study values of δ are presented based on experimental measurements under inert (CO2) sweep: using a permeation flux model and local PO2 measurements, collected by means of a local gas-sampling probe in our large-scale reactor, we can determine δ directly. The ITM assessed was La0.9Ca0.1FeO3-δ (LCF); the relative resistances to JO2 were quantified using the pre-defined permeation flux model and local PO2 values. Across a temperature range from 825°C to 1056°C, δ was found to vary from 0.007 to 0.029 (<1%), safely within material stability limits, whilst the permeate surface exchange resistance dominates. An inert JO2 limit was identified owing to a maximum sweep surface δ, δmaxinert. The physical presence of δmaxinert is attributed to a rate limiting step shift from desorption to associative electron transfer steps on the sweep surface as PO2 is reduced. Permeate surface exchange limitations under non-reactive conditions suggest that reactive (fuel) operation is necessary to accelerate surface chemistry for future work, to reduce flux resistance and push δpast δmaxinert in a stable manner.

  17. Lipid engineering reveals regulatory roles for membrane fluidity in yeast flocculation and oxygen-limited growth

    DEFF Research Database (Denmark)

    Degreif, Daniel; de Rond, Tristan; Bertl, Adam

    2017-01-01

    Cells modulate lipid metabolism in order to maintain membrane homeostasis. Here we use a metabolic engineering approach to manipulate the stoichiometry of fatty acid unsaturation, a regulator of cell membrane fluidity, in Saccharomyces cerevisiae. Unexpectedly, reduced lipid unsaturation triggere...

  18. Comparison of the Effectiveness of Pars Plana Vitrectomy with and without Internal Limiting Membrane Peeling for Idiopathic Retinal Membrane Removal: A Meta-Analysis.

    Science.gov (United States)

    Liu, Hanhan; Zuo, Shanru; Ding, Chun; Dai, Xunzhang; Zhu, Xiaohua

    2015-01-01

    We conducted a meta-analysis of published retrospective studies and compared the effectiveness of pars plana vitrectomy with and without internal limiting membrane (ILM) peeling for idiopathic epiretinal membrane (IERM). The results revealed that patients in the IERM+ILM peeling group had better BCVA after surgery within 12 months than those in IERM peeling group. But patients in the IERM peeling group showed better BCVA in the 18th month. More retrospective studies or randomized controlled trials are required to investigate and compare the long-term effect of IERM removal with and without ILM peeling.

  19. Comparison of the Effectiveness of Pars Plana Vitrectomy with and without Internal Limiting Membrane Peeling for Idiopathic Retinal Membrane Removal: A Meta-Analysis

    Directory of Open Access Journals (Sweden)

    Hanhan Liu

    2015-01-01

    Full Text Available We conducted a meta-analysis of published retrospective studies and compared the effectiveness of pars plana vitrectomy with and without internal limiting membrane (ILM peeling for idiopathic epiretinal membrane (IERM. The results revealed that patients in the IERM+ILM peeling group had better BCVA after surgery within 12 months than those in IERM peeling group. But patients in the IERM peeling group showed better BCVA in the 18th month. More retrospective studies or randomized controlled trials are required to investigate and compare the long-term effect of IERM removal with and without ILM peeling.

  20. Pars Plana Vitrectomy with Internal Limiting Membrane Peeling in Patients with Myopic Foveoschisis

    Directory of Open Access Journals (Sweden)

    Kemal Yuksel

    2016-06-01

    Full Text Available Objective: To report the clinical and surgical outcomes of patients with myopic foveoschisis (MF. Methods: Thirteen eyes in ten symptomatic MF patients who underwent pars plana vitrectomy (PPV and gas tampon­ade with internal limiting membrane (ILM peeling were retrospectively identified. Best corrected visual acuity (BCVA and central foveal thickness (CFT were assessed preoperatively and six months postoperatively. Complications during and after surgery were also recorded. Results: The median BCVA significantly improved from 20/160 to 20/100 (p = 0.03. In subgroup analysis, eight eyes (61% demonstrated significant BCVA improvements from 20/80 to 20/50 (p < 0.001, whereas five eyes had similar BCVA with preoperative level after six months of surgery (p=0.32. The mean CFT decreased from 526 microns at base­line to 214 microns at six months of surgery (p < 0.001. Optical coherence tomography scans revealed a complete MF resolution in ten eyes (76% and a partial MF resolution in three eyes. Peripheral retinal tear was developed in one patient during surgery and one patient had cataract after surgery, those were treated accordingly. Conclusion: PPV with ILM peeling followed by gas tamponade is a safe and effective procedure for the treatment of eyes with myopic foveoschisis. Larger studies with longer follow-ups will further establish the efficacy and safety of this procedure. J Clin Exp Invest 2016; 7 (2: 139-143

  1. Does Internal Limiting Membrane Peeling in Macular Hole Surgery Improve Reading Vision?

    Directory of Open Access Journals (Sweden)

    Das Taraprasad

    2003-01-01

    Full Text Available Purpose: To document the effect of internal limiting membrane (ILM peeling in macular hole closure and reading vision. Method: Fifty-four patients with idiopathic and traumatic macular hole underwent standard vitreous surgery and received either ILM peeling (n= 25 or no ILM peeling (n= 29. The hole closure, and Snellen acuity (distant and near were recorded 12 weeks after surgery and statistically analysed. Results: The macular hole closure rate was 96% (24 of 25 and 72.4% (21 of 29 with and without ILM peeling respectively (P = 0.028. Distant vision improvement of two or more lines was recorded in 64% (16 of 25 and 51.7% (15 of 29 eyes (P = 0.417 with and without ILM peeling respectively. Near vision improvement of two or more lines was seen in 68% (17 of 25 and 41.2% (12 of 29 eyes (P = 0.048 with and without ILM peeling respectively. Conclusion: ILM peeling in macular hole surgery improves the macular hole closure rate and reading vision.

  2. [Internal limiting membrane role in primary surgery of the macular hole].

    Science.gov (United States)

    Brănişteanu, D; Moraru, Andreea

    2013-01-01

    To assess the anatomical result after primary macular hole surgery with or without internal limiting membrane (ILM) peeling. To assess the safety and stability results; Prospective, comparative, interventional case study of 47 eyes with stage 3 or 4 macular hole treated by pars-plana vitrectomy between 2006 and 2011. In 19 cases (40.42%) only posterior hyaloid was removed (control group) while in the other 28 cases (59.57%) additional ILM peeling was performed. All cases had gas endotamponade. Postoperatively the cases were followed-up at least 6 months clinically and by OCT. Statistical analysis was performed using ANOVA and Wilcoxon tests. The mean age of patients in the study was 54, 47 +/- 4, 83 years (ranging from 47 to 74 years). In 36 cases (76.59%) the macular hole was idiopathic. After surgery, the macular hole closed in 22 out of 28 cases with ILM peeling (78.57%) as compared to only 13 out of 19 cases from the control group (68.42%). No intraoperative complications were noted. Main postoperative complications were cataract augmentation and macular hole enlargement in 4 out of 12 failed cases (33.33%). No recurrence was noted if macular hole closed after surgery. These results confirm the stability, safety and efficacy of both techniques but with a significant higher success rate if ILM is peeled. The main postoperative complication was macular hole enlargement if surgery failed.

  3. Accidental subretinal brilliant blue G migration during internal limiting membrane peeling surgery.

    Science.gov (United States)

    Almeida, Felipe P P; De Lucca, Ana Claudia; Scott, Ingrid Ursula; Jorge, Rodrigo; Messias, Andre

    2015-01-01

    This case report describes a man who developed retinal changes in his right eye associated with brilliant blue G migration into the subretinal space during 2 years of follow-up. The patient's best-corrected visual acuity in the right eye was 20/70 before surgery, and it improved to 20/25 at 1 year after surgery. Fluorescein angiography showed staining during the late phase in the central macula at all follow-up visits after surgery. Multifocal electroretinography demonstrated normal amplitude and implicit times before surgery but decreased amplitudes and increased implicit times in at least 5 contiguous hexagons after surgery on all 3 examinations performed during the 2-year follow-up period. These functional changes were not topographically correlated with the area of fluorescein staining or with the internal limiting membrane peeled area, but were matched to the area where brilliant blue G accidentally entered the subretinal space. Microperimetry demonstrated reduced retinal threshold sensitivity, particularly in areas with decreased multifocal electroretinography amplitude. Despite the visual acuity improvement observed in this case, multifocal electroretinography and microperimetry indicate that subretinal brilliant blue G might cause focal macular damage with a decrease of macular function suggestive of a toxic effect.

  4. Defects in the outer limiting membrane are associated with rosette development in the Nrl-/- retina.

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    Michael W Stuck

    Full Text Available The neural retinal leucine zipper (Nrl knockout mouse is a widely used model to study cone photoreceptor development, physiology, and molecular biology in the absence of rods. In the Nrl(-/- retina, rods are converted into functional cone-like cells. The Nrl(-/- retina is characterized by large undulations of the outer nuclear layer (ONL commonly known as rosettes. Here we explore the mechanism of rosette development in the Nrl(-/- retina. We report that rosettes first appear at postnatal day (P8, and that the structure of nascent rosettes is morphologically distinct from what is seen in the adult retina. The lumen of these nascent rosettes contains a population of aberrant cells protruding into the subretinal space that induce infolding of the ONL. Morphologically adult rosettes do not contain any cell bodies and are first detected at P15. The cells found in nascent rosettes are photoreceptors in origin but lack inner and outer segments. We show that the adherens junctions between photoreceptors and Müller glia which comprise the retinal outer limiting membrane (OLM are not uniformly formed in the Nrl(-/- retina and thus allow protrusion of a population of developing photoreceptors into the subretinal space where their maturation becomes delayed. These data suggest that the rosettes of the Nrl(-/- retina arise due to defects in the OLM and delayed maturation of a subset of photoreceptors, and that rods may play an important role in the proper formation of the OLM.

  5. Defects in the outer limiting membrane are associated with rosette development in the Nrl-/- retina.

    Science.gov (United States)

    Stuck, Michael W; Conley, Shannon M; Naash, Muna I

    2012-01-01

    The neural retinal leucine zipper (Nrl) knockout mouse is a widely used model to study cone photoreceptor development, physiology, and molecular biology in the absence of rods. In the Nrl(-/-) retina, rods are converted into functional cone-like cells. The Nrl(-/-) retina is characterized by large undulations of the outer nuclear layer (ONL) commonly known as rosettes. Here we explore the mechanism of rosette development in the Nrl(-/-) retina. We report that rosettes first appear at postnatal day (P)8, and that the structure of nascent rosettes is morphologically distinct from what is seen in the adult retina. The lumen of these nascent rosettes contains a population of aberrant cells protruding into the subretinal space that induce infolding of the ONL. Morphologically adult rosettes do not contain any cell bodies and are first detected at P15. The cells found in nascent rosettes are photoreceptors in origin but lack inner and outer segments. We show that the adherens junctions between photoreceptors and Müller glia which comprise the retinal outer limiting membrane (OLM) are not uniformly formed in the Nrl(-/-) retina and thus allow protrusion of a population of developing photoreceptors into the subretinal space where their maturation becomes delayed. These data suggest that the rosettes of the Nrl(-/-) retina arise due to defects in the OLM and delayed maturation of a subset of photoreceptors, and that rods may play an important role in the proper formation of the OLM.

  6. Serous macular detachment, yellow macular deposits, and prominent middle limiting membrane in multiple myeloma

    Directory of Open Access Journals (Sweden)

    Dogan B

    2015-04-01

    Full Text Available Berna Dogan,1 Muhammet Kazim Erol,1 Devrim Toslak,1 Deniz Turgut Coban,1 Mehmet Bulut,1 Ayse Cengiz,1 Esin Sogutlu Sari2 1Antalya Training and Research Hospital, Eye Clinic, Antalya, Turkey; 2Balikesir University Medicine Faculty, Eye Clinic, Balikesir, Turkey Abstract: Bone marrow-derived multiple myeloma is a type of plasma cell tumor that may be associated with ocular complications. A 52-year-old male patient was admitted to our eye clinic with the complaint of sudden visual loss and a visual acuity of 20/50 in the right eye and 20/800 in the left eye. Fundus examination revealed common flame-shaped hemorrhages, venous dilatation and tortuosity, Roth spots, serous macular detachment, and yellow macular deposits in both eyes. Evaluation with fundus fluorescein angiography, fundus autofluorescence, and spectral-domain optical coherence tomography resulted in suspicion of hyperviscosity retinopathy and referral to the hematology clinic. After hematology consultation confirmed a diagnosis of multiple myeloma, chemotherapy and plasmapheresis were initiated. Four months after presentation, best-corrected visual acuity was 20/20 in both eyes and improvement in hyperviscosity retinopathy, serous macular detachment, and yellow macular deposits was observed. Keywords: serous macular detachment, yellow macular deposit, prominent middle limiting membrane, multiple myeloma

  7. Alveolar-membrane diffusing capacity limits performance in Boston marathon qualifiers.

    Directory of Open Access Journals (Sweden)

    Kaleen M Lavin

    Full Text Available PURPOSE: (1 to examine the relation between pulmonary diffusing capacity and marathon finishing time, and (2, to evaluate the accuracy of pulmonary diffusing capacity for nitric oxide (DLNO in predicting marathon finishing time relative to that of pulmonary diffusing capacity for carbon monoxide (DLCO. METHODS: 28 runners [18 males, age = 37 (SD 9 years, body mass = 70 (13 kg, height = 173 (9 cm, percent body fat = 17 (7 %] completed a test battery consisting of measurement of DLNO and DLCO at rest, and a graded exercise test to determine running economy and aerobic capacity prior to the 2011 Steamtown Marathon (Scranton, PA. One to three weeks later, all runners completed the marathon (range: 2:22:38 to 4:48:55. Linear regressions determined the relation between finishing time and a variety of anthropometric characteristics, resting lung function variables, and exercise parameters. RESULTS: In runners meeting Boston Marathon qualification standards, 74% of the variance in marathon finishing time was accounted for by differences in DLNO relative to body surface area (BSA (SEE = 11.8 min, p<0.01; however, the relation between DLNO or DLCO to finishing time was non-significant in the non-qualifiers (p = 0.14 to 0.46. Whereas both DLCO and DLNO were predictive of finishing time for all finishers, DLNO showed a stronger relation (r(2 = 0.30, SEE = 33.4 min, p<0.01 compared to DLCO when considering BSA. CONCLUSION: DLNO is a performance-limiting factor in only Boston qualifiers. This suggests that alveolar-capillary membrane conductance is a limitation to performance in faster marathoners. Additionally, DLNO/BSA predicts marathon finishing time and aerobic capacity more accurately than DLCO.

  8. A direct contact between astrocyte and vitreous body is possible in the rabbit eye due to discontinuities in the basement membrane of the retinal inner limiting membrane

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    A. Haddad

    2003-02-01

    Full Text Available Different from most mammalian species, the optic nerve of the rabbit eye is initially formed inside the retina where myelination of the axons of the ganglion cells starts and vascularization occurs. Astrocytes are confined to these regions. The aforementioned nerve fibers known as medullated nerve fibers form two bundles that may be identified with the naked eye. The blood vessels run on the inner surface of these nerve fiber bundles (epivascularization and, accordingly, the accompanying astrocytes lie mostly facing the vitreous body from which they are separated only by the inner limiting membrane of the retina. The arrangement of the astrocytes around blood vessels leads to the formation of structures known as glial tufts. Fragments (N = 3 or whole pieces (N = 3 of the medullated nerve fiber region of three-month-old male rabbits (Orictolagus cuniculus were fixed in glutaraldehyde followed by osmium tetroxide, and their thin sections were examined with a transmission electron microscope. Randomly located discontinuities (up to a few micrometers long of the basement membrane of the inner limiting membrane of the retina were observed in the glial tufts. As a consequence, a direct contact between the astrocyte plasma membrane and vitreous elements was demonstrated, making possible functional interactions such as macromolecular exchanges between this glial cell type and the components of the vitreous body.

  9. Adaptive tracking control for double-pendulum overhead cranes subject to tracking error limitation, parametric uncertainties and external disturbances

    Science.gov (United States)

    Zhang, Menghua; Ma, Xin; Rong, Xuewen; Tian, Xincheng; Li, Yibin

    2016-08-01

    In a practical application, overhead cranes are usually subjected to system parameter uncertainties, such as uncertain payload masses, cable lengths, frictions, and external disturbances, such as air resistance. Most existing crane control methods treat the payload swing as that of a single-pendulum. However, certain types of payloads and hoisting mechanisms result in double-pendulum dynamics. The double-pendulum effects will make most existing crane control methods fail to work normally. Therefore, an adaptive tracking controller for double-pendulum overhead cranes subject to parametric uncertainties and external disturbances is developed in this paper. The proposed adaptive tracking control method guarantees that the trolley tracking error is always within a prior set of boundary conditions and converges to zero rapidly. The asymptotic stability of the closed-loop system's equilibrium point is assured by Lyapunov techniques and Barbalat's Lemma. Simulation results show that the proposed adaptive tracking control method is robust with respect to system parametric uncertainties and external disturbances.

  10. Influence of the external conditions on salt retention and pressure-induced electrical potential measured across a composite membrane

    DEFF Research Database (Denmark)

    Benavente, Juana; Jonsson, Gunnar Eigil

    1999-01-01

    Transport on single electrolyte solutions (NaCl and MgCl2) due to pressure gradients across a commercial reverse osmosis membrane was studied by measuring volume flux (J(v)), salt rejection (S) and pressure induced electrical potential (Delta E) in a crossflow cell. The influence on these paramet......Transport on single electrolyte solutions (NaCl and MgCl2) due to pressure gradients across a commercial reverse osmosis membrane was studied by measuring volume flux (J(v)), salt rejection (S) and pressure induced electrical potential (Delta E) in a crossflow cell. The influence...

  11. Treatment of distal radius fractures with external fixation, limited open reduction and dorsal autologous cancellous onlay bone grafting

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    Mordechai Vigler

    2012-04-01

    Conclusion: Compared to current published results of distal radial fractures treated with external fixation supplemented with packed intramedullary autologous cancellous iliac crest graft, our dorsal on- lay technique is as effective a treatment modality. Additionally, there are several advantages including less bone graft to be harvested and associated morbidity. [Hand Microsurg 2012; 1(1.000: 10-16

  12. Behaviour of bipolar membranes at high current density. Water diffusion limitation

    NARCIS (Netherlands)

    Krol, J.J.; Jansink, M.G.J.; Wessling, Matthias; Strathmann, H.

    1998-01-01

    In this paper the behaviour of bipolar membranes at very high current density is discussed. Current–voltage curves are determined, both for the Tokuyama Soda BP-1 and the WSI Technologies bipolar membrane. The current–voltage curves are characterised by an inflection point at which a drastic

  13. Value of internal limiting membrane peeling in surgery for idiopathic macular hole stage 2 and 3: a randomised clinical trial

    DEFF Research Database (Denmark)

    Christensen, U C; Krøyer, K; Sander, B

    2009-01-01

    AIM: To determine the effect of internal limiting membrane (ILM) peeling on anatomical and functional success rates in stage 2 and 3 idiopathic macular hole surgery (MHS). METHODS: Randomised clinical trial of stage 2 and 3 idiopathic macular hole without visible epiretinal fibrosis and with less...

  14. The permeability of SPION over an artificial three-layer membrane is enhanced by external magnetic field

    Directory of Open Access Journals (Sweden)

    Ge Xianxi

    2006-04-01

    Full Text Available Abstract Background Sensorineural hearing loss, a subset of all clinical hearing loss, may be correctable through the use of gene therapy. We are testing a delivery system of therapeutics through a 3 cell-layer round window membrane model (RWM model that may provide an entry of drugs or genes to the inner ear. We designed an in vitro RWM model similar to the RWM (will be referred to throughout the paper as RWM model to determine the feasibility of using superparamagnetic iron oxide (Fe3O4 nanoparticles (SPION for targeted delivery of therapeutics to the inner ear. The RWM model is a 3 cell-layer model with epithelial cells cultured on both sides of a small intestinal submucosal (SIS matrix and fibroblasts seeded in between. Dextran encapsulated nanoparticle clusters 130 nm in diameter were pulled through the RWM model using permanent magnets with flux density 0.410 Tesla at the pole face. The SIS membranes were harvested at day 7 and then fixed in 4% paraformaldehyde. Transmission electron microscopy and fluorescence spectrophotometry were used to verify transepithelial transport of the SPION across the cell-culture model. Histological sections were examined for evidence of SPION toxicity, as well to generate a timeline of the position of the SPION at different times. SPION also were added to cells in culture to assess in vitro toxicity. Results Transepithelial electrical resistance measurements confirmed epithelial confluence, as SPION crossed a membrane consisting of three co-cultured layers of cells, under the influence of a magnetic field. Micrographs showed SPION distributed throughout the membrane model, in between cell layers, and sometimes on the surface of cells. TEM verified that the SPION were pulled through the membrane into the culture well below. Fluorescence spectrophotometry quantified the number of SPION that went through the SIS membrane. SPION showed no toxicity to cells in culture. Conclusion A three-cell layer model of the

  15. Dicarboxylic acids with limited numbers of hydrocarbons stabilize cell membrane and increase osmotic resistance in rat erythrocytes.

    Science.gov (United States)

    Mineo, Hitoshi; Amita, Nozomi; Kawawake, Megumi; Higuchi, Ayaka

    2013-11-01

    We examined the effect of dicarboxylic acids having 0 to 6 hydrocarbons and their corresponding monocarboxylic or tricarboxylic acids in changing the osmotic fragility (OF) in rat red blood cells (RBCs). Malonic, succinic, glutaric and adipic acids, which are dicarboxylic acids with 1, 2, 3 and 4 straight hydrocarbons located between two carboxylic groups, decreased the OF in a concentration-dependent manner. Other long-chain dicarboxylic acids did not change the OF in rat RBCs. The benzoic acid derivatives, isophthalic and terephthalic acids, but not phthalic acid, decreased the OF in a concentration-dependent manner. Benzene-1,2,3-tricarboxylic acid, but not benzene-1,3,5-tricarboxylic acid, also decreased the OF in rat RBCs. On the other hand, monocarboxylic acids possessing 2 to 7 straight hydrocarbons and benzoic acid increased the OF in rat RBCs. In short-chain dicarboxylic acids, a limited number of hydrocarbons between the two carboxylic groups are thought to form a V- or U-shaped structure and interact with phospholipids in the RBC membrane. In benzene dicarboxylic and tricarboxylic acids, a part of benzene nucleus between the two carboxylic groups is thought to enter the plasma membrane and act on acyl-chain in phospholipids in the RBC membrane. For dicarboxylic and tricarboxylic acids, limited numbers of hydrocarbons in molecules are speculated to enter the RBC membrane with the hydrophilic carboxylic groups remaining outside, stabilizing the structure of the cell membrane and resulting in an increase in osmotic resistance in rat RBCs.

  16. Photoreceptor Outer Segment on Internal Limiting Membrane after Macular Hole Surgery: Implications for Pathogenesis

    Directory of Open Access Journals (Sweden)

    Michael E. Grinton

    2015-09-01

    Full Text Available Purpose: This report presents a case, which highlights key principles in the pathophysiology of macular holes. It has been hypothesized that anteroposterior (AP and tangential vitreous traction on the fovea are the primary underlying factors causing macular holes [Nischal and Pearson; in Kanski and Bowling: Clinical Ophthalmology: A Systemic Approach, 2011, pp 629-631]. Spectral domain optical coherence tomography (OCT has subsequently corroborated this theory in part but shown that AP vitreofoveal traction is the more common scenario [Steel and Lotery: Eye 2013;27:1-21]. Methods: This study was conducted as a single case report. Results: A 63-year old female presented to her optician with blurred and distorted vision in her left eye. OCT showed a macular hole with a minimum linear diameter of 370 µm, with persistent broad vitreofoveal attachment on both sides of the hole edges. The patient underwent combined left phacoemulsification and pars plana vitrectomy, internal limiting membrane (ILM peel and gas injection. The ILM was examined by electron microscopy and showed the presence of a cone outer segment on the retinal side. Post-operative OCT at 11 weeks showed a closed hole with recovery of the foveal contour and good vision. Conclusion: Our case shows the presence of a photoreceptor outer segment on the retinal side of the ILM and reinforces the importance of tangential traction in the development of some macula holes. The case highlights the theory of transmission of inner retinal forces to the photoreceptors via Müller cells and how a full thickness macular hole defect can occur in the absence of AP vitreomacular traction.

  17. Photoreceptor Outer Segment on Internal Limiting Membrane after Macular Hole Surgery: Implications for Pathogenesis

    Science.gov (United States)

    Grinton, Michael E.; Sandinha, Maria T.; Steel, David H.W.

    2015-01-01

    Purpose This report presents a case, which highlights key principles in the pathophysiology of macular holes. It has been hypothesized that anteroposterior (AP) and tangential vitreous traction on the fovea are the primary underlying factors causing macular holes [Nischal and Pearson; in Kanski and Bowling: Clinical Ophthalmology: A Systemic Approach, 2011, pp 629–631]. Spectral domain optical coherence tomography (OCT) has subsequently corroborated this theory in part but shown that AP vitreofoveal traction is the more common scenario [Steel and Lotery: Eye 2013;27:1–21]. Methods This study was conducted as a single case report. Results A 63-year old female presented to her optician with blurred and distorted vision in her left eye. OCT showed a macular hole with a minimum linear diameter of 370 µm, with persistent broad vitreofoveal attachment on both sides of the hole edges. The patient underwent combined left phacoemulsification and pars plana vitrectomy, internal limiting membrane (ILM) peel and gas injection. The ILM was examined by electron microscopy and showed the presence of a cone outer segment on the retinal side. Post-operative OCT at 11 weeks showed a closed hole with recovery of the foveal contour and good vision. Conclusion Our case shows the presence of a photoreceptor outer segment on the retinal side of the ILM and reinforces the importance of tangential traction in the development of some macula holes. The case highlights the theory of transmission of inner retinal forces to the photoreceptors via Müller cells and how a full thickness macular hole defect can occur in the absence of AP vitreomacular traction. PMID:26557083

  18. Indocyanine green-assisted internal limiting membrane peeling in macular hole surgery: a meta-analysis.

    Directory of Open Access Journals (Sweden)

    Yan Wu

    Full Text Available BACKGROUND: The opinion of application of indocyanine green (ICG in the macular hole surgery was contradictory. Here we conducted a meta-analysis to evaluate the effect of in internal limiting membrane (ILM peeling for macular hole surgery. METHODS AND FINDINGS: We searched electronic databases for comparative studies published before July 2012 of ILM peeling with and without ICG. Twenty-two studies including 1585 eyes were included. Visual acuity (VA improvement, including the postoperative rate of ≥20/40 VA gained (OR, 0.65; 95% CI, 0.43 to 0.97; P = 0.033 and increased LogMAR (WMD, -0.09; 95% CI, -0.16 to -0.02; P = 0.011, was less in the ICG group. The risk of visual field defects was greater in the ICG group than in the non-ICG group. There was no significant difference in the rate of anatomical outcomes between ILM peeling procedures performed with and without ICG. RPE changes and other postoperative complications were not significantly different between the ICG and non-ICG groups. An additional analysis showed that the VA improvement of the ICG group was less than the non-ICG group only within the first year of follow up. A subgroup analysis showed that the rate of VA improvement was lower in the ICG group than in other adjuncts group. A higher rate of secondary closure and less VA improvement were observed in a high proportion (>0.1% of the ICG group. A sensitivity analysis after the randomized-controlled trials were excluded from the meta-analysis demonstrated no differences compared with the overall results. CONCLUSIONS: This meta-analysis demonstrated that there is no evidence of clinical superiority in outcomes for ICG-assisted ILM peeling procedure over the non-ICG one. The toxicity of ICG should be considered when choosing the various staining methods.

  19. The interaction between the membrane-proximal external region and the N-trimer region of HIV- 1 gp41: Involvement in viral fusion

    Institute of Scientific and Technical Information of China (English)

    LI Jing; LU Lu; WU Fan; CHEN Xi; NIU Ben; JIANG ShiBo; CHEN YingHua

    2009-01-01

    The membrane proximal external region (MPER) of gp41 is extremely conserved among diverse HIV-1 variants, implying its important role in viral infection. Interestingly, two of the most broadly neutralizing antibodies, 2F5 and 4E10, specifically recognize this region. Our previous study demonstrated that the antigenicity and immunogenicity of 4E10 epitope are affected by remodeling gp41 fusion core, sug-gesting that the MPER may be associated with gp41 core and involved in gp41-mediated membrane fusion. Here we measured the binding activity of 4E10 epitope peptide (D4E10P) with various gp41 core-derived peptides and found that the N-trimer region in a construct designated N-trimer-6HB in-teracted significantly with D4E10P. Using N-trimer-6HB to screen a phage library, we identified a motif (WF) located in 4E10 epitope that may play a certain role in the interaction of gp41 MPER with the N-trimer in gp41 fusion core and, we thus speculated upon the potential involvement of MPER in the usion process between viral envelope and target cell membrane.

  20. The Atomic Structure of the HIV-1 gp41 Transmembrane Domain and Its Connection to the Immunogenic Membrane-proximal External Region.

    Science.gov (United States)

    Apellániz, Beatriz; Rujas, Edurne; Serrano, Soraya; Morante, Koldo; Tsumoto, Kouhei; Caaveiro, Jose M M; Jiménez, M Ángeles; Nieva, José L

    2015-05-22

    The membrane-proximal external region (MPER) C-terminal segment and the transmembrane domain (TMD) of gp41 are involved in HIV-1 envelope glycoprotein-mediated fusion and modulation of immune responses during viral infection. However, the atomic structure of this functional region remains unsolved. Here, based on the high resolution NMR data obtained for peptides spanning the C-terminal segment of MPER and the TMD, we report two main findings: (i) the conformational variability of the TMD helix at a membrane-buried position; and (ii) the existence of an uninterrupted α-helix spanning MPER and the N-terminal region of the TMD. Thus, our structural data provide evidence for the bipartite organization of TMD predicted by previous molecular dynamics simulations and functional studies, but they do not support the breaking of the helix at Lys-683, as was suggested by some models to mark the initiation of the TMD anchor. Antibody binding energetics examined with isothermal titration calorimetry and humoral responses elicited in rabbits by peptide-based vaccines further support the relevance of a continuous MPER-TMD helix for immune recognition. We conclude that the transmembrane anchor of HIV-1 envelope is composed of two distinct subdomains: 1) an immunogenic helix at the N terminus also involved in promoting membrane fusion; and 2) an immunosuppressive helix at the C terminus, which might also contribute to the late stages of the fusion process. The unprecedented high resolution structural data reported here may guide future vaccine and inhibitor developments.

  1. External fixation combined with limited internal fixation for Pilon fractures%外固定支架结合有限内固定治疗Pilon骨折

    Institute of Scientific and Technical Information of China (English)

    周淮; 徐晓军

    2011-01-01

    Objective To investigate the clinical effect of Pilon fractures treated with external fixation and limited internal fixation.Methods 24 cases of Pilon fractures of tibia were treated with external fixation combined limited internal fixation.Results 24 cases were followed up for 10 ~ 20 months.No bone nonumon or skin necrosis complication was found.According to Mazur ankle joint scoring system, the results were excellent in 14, good in 7 , and fair in 3.Conclusions External fixation combined with limited internal fixation can immohilize the sections of fracture and achieve excellent ankle joint function,so it is an effective surgical treatment of Pilon fractures.%目的 探讨外固定支架结合有限内固定治疗Pilon骨折的疗效.方法 采用外固定支架结合有限内固定治疗24例Pilon骨折.结果 24例均获得随访,时间10~20个月.无骨不连、皮肤坏死发生.踝关节功能Mazur评分:优14例,良7例,可3例.结论 外固定支架结合有限内固定可以获得术后骨折稳定,取得良好踝关节功能,是治疗Pilon骨折有效的手术方案.

  2. Vitrectomy and internal limiting membrane peeling for macular folds secondary to hypotony in myopes

    Directory of Open Access Journals (Sweden)

    Nadal J

    2015-05-01

    Full Text Available Jeroni Nadal,1–3 Elisa Carreras,2,3 Maria Isabel Canut,1–3 Rafael I Barraquer1–3 1Centro de Oftalmologia Barraquer, 2Universitat Autònoma de Barcelona, 3Instituto Barraquer, Barcelona, Spain Background: Hypotony maculopathy (HM changes may persist, and visual acuity remains poor, despite normalization of intraocular pressure (IOP. The aim of this study was to evaluate the visual and anatomical results of pars plana vitrectomy (PPV, internal limiting membrane (ILM peeling, and 20% SF6 gas tamponade in five myopic patients with HM.Methods: This retrospective interventional study was conducted at the Barraquer Center of Ophthalmology, a tertiary care center in Barcelona, Spain, and included five eyes from five consecutive patients (aged 55.4±13.1 years with HM caused by different conditions. All the patients were treated with 23-gauge PPV, ILM peeling, and 20% SF6 gas tamponade. Preoperative and postoperative evaluation was performed using anterior and posterior biomicroscopy and best corrected visual acuity (BCVA by logMAR charts.Results: Before surgery, median spherical equivalent was -13.1 (range -7, -19 diopters of myopia. Preoperatively, four cases presented IOP <6.5 mmHg for 3 (range 2–8 weeks. In three of these four cases, IOP >6.5 mmHg was achieved over 16 (range 16–28 weeks, without resolution of HM; increased IOP was not achieved in the remaining case treated 2 weeks after diagnosis of HM. One case presented IOP >6.5 mmHg with HM for 28 weeks before surgery. Preoperative BCVA was 0.7 (range 0.26–2.3 logMAR, and 0.6 (range 0.3–0.7 logMAR and 0.5 (range 0.2–1 logMAR, respectively, at 4 and 12 months after surgery. There was no statistically significant difference between preoperative and postoperative BCVA. Hyperpigmentation lines in the macular area were observed in three cases with hypotony. These lines progressed after surgery despite resolution of the retinal folds in the three cases, and BCVA decreased in parallel

  3. Vitrectomy with internal limiting membrane peeling for macular hole in high myopia eyes

    Directory of Open Access Journals (Sweden)

    Chun-Mei Deng

    2015-08-01

    Full Text Available AIM: To compare the clinical effects between pars plana vitrectomy(PPVand PPV with internal limiting membrane peeling(ILMPfor macular hole in high myopia eyes. METHODS:The clinical data of 33 high myopia with macular hole patients(36 eyeswith or without retinal detachment caused by macular hole were retrospectively analyzed. The patients were divided into two groups according to different operation methods: 15 eyes in groupⅠhad undergone PPV; 21 eyes in groupⅡhad undergone PPV with ILMPP peeling. According to different conditions of patients,different auxiliary methods were accepted, such as silicone oil tamponade, C3F8 tamponade, photocoagulation, condensation, etc. The follow-up period was 3~12mo. Best corrected visual acuity(BCVA, macular hole closure rate and retinal reattachment rate were continuous checked after operation. Then we evaluated the outcome in the two groups by statistical analysis.RESULTS: The postoperative mean BCVA increased by 0.167 in group Ⅰand 0.456 in group Ⅱ than preoperative, the difference was significant(t=2.46,6.753; P=0.027,0.000. And the difference of BCVA improvement was significant between those two groups(t=-2.943, P=0.006. The macular hole closed in 7 eyes(46.67%in group Ⅰ,and 18 eyes(85.71%in group Ⅱ; The difference was significant between those two groups(χ2=6.287,P=0.025.Retinal reattachment was found in 11 eyes(91.67%in group Ⅰ and 19 eyes(94.73%in group Ⅱ. The difference was not significant between the two groups(χ2=0.856, P=0.418. CONCLUSION: PPV with ILMPP peeling for macular hole in high myopia eyes can obviously improve closure of macular hole and postoperative visual acuity. But the difference of retinal reattachment rate was not significant between peeling and unpeeling of ILMP.

  4. Vitrectomy and internal limiting membrane peeling for macular folds secondary to hypotony in myopes

    Science.gov (United States)

    Nadal, Jeroni; Carreras, Elisa; Canut, Maria Isabel; Barraquer, Rafael I

    2015-01-01

    Background Hypotony maculopathy (HM) changes may persist, and visual acuity remains poor, despite normalization of intraocular pressure (IOP). The aim of this study was to evaluate the visual and anatomical results of pars plana vitrectomy (PPV), internal limiting membrane (ILM) peeling, and 20% SF6 gas tamponade in five myopic patients with HM. Methods This retrospective interventional study was conducted at the Barraquer Center of Ophthalmology, a tertiary care center in Barcelona, Spain, and included five eyes from five consecutive patients (aged 55.4±13.1 years) with HM caused by different conditions. All the patients were treated with 23-gauge PPV, ILM peeling, and 20% SF6 gas tamponade. Preoperative and postoperative evaluation was performed using anterior and posterior biomicroscopy and best corrected visual acuity (BCVA) by logMAR charts. Results Before surgery, median spherical equivalent was −13.1 (range −7, −19) diopters of myopia. Preoperatively, four cases presented IOP 6.5 mmHg was achieved over 16 (range 16–28) weeks, without resolution of HM; increased IOP was not achieved in the remaining case treated 2 weeks after diagnosis of HM. One case presented IOP >6.5 mmHg with HM for 28 weeks before surgery. Preoperative BCVA was 0.7 (range 0.26–2.3) logMAR, and 0.6 (range 0.3–0.7) logMAR and 0.5 (range 0.2–1) logMAR, respectively, at 4 and 12 months after surgery. There was no statistically significant difference between preoperative and postoperative BCVA. Hyper-pigmentation lines in the macular area were observed in three cases with hypotony. These lines progressed after surgery despite resolution of the retinal folds in the three cases, and BCVA decreased in parallel in two of these cases. Conclusion PPV with ILM peeling followed by gas tamponade is a good alternative for the treatment of HM in myopic patients. However, persistent choroidal folds may compromise BCVA. We therefore recommend initiating treatment as early as possible. PMID

  5. Strength degradation and failure limits of dense and porous ceramic membrane materials

    DEFF Research Database (Denmark)

    Pećanac, G.; Foghmoes, Søren Preben Vagn; Lipińska-Chwałek, M.;

    2013-01-01

    Thin dense membrane layers, mechanically supported by porous substrates, are considered as the most efficient designs for oxygen supply units used in Oxy-fuel processes and membrane reactors. Based on the favorable permeation properties and chemical stability, several materials were suggested...... as promising membrane and substrate materials: Ba0.5Sr0.5Co0.8Fe0.2O3−δ, La0.6−xSr0.4Co0.2Fe0.8O3−δ (x=0, 0.02) and Ce0.9Gd0.1O1.95−δ. Although membranes operate at elevated temperatures, the ends of tubes in certain three-end concepts remain almost at room temperature. The current work concentrates...... on the failure potential of these membrane parts, where in a complex device also the highest residual stresses should arise due to differences in thermal expansion. In particular, sensitivity of the materials to subcritical crack growth was assessed since the long-term reliability of the component does not only...

  6. Receptor clustering affects signal transduction at the membrane level in the reaction-limited regime

    Science.gov (United States)

    Caré, Bertrand R.; Soula, Hédi A.

    2013-01-01

    Many types of membrane receptors are found to be organized as clusters on the cell surface. We investigate the potential effect of such receptor clustering on the intracellular signal transduction stage. We consider a canonical pathway with a membrane receptor (R) activating a membrane-bound intracellular relay protein (G). We use Monte Carlo simulations to recreate biochemical reactions using different receptor spatial distributions and explore the dynamics of the signal transduction. Results show that activation of G by R is severely impaired by R clustering, leading to an apparent blunted biological effect compared to control. Paradoxically, this clustering decreases the half maximal effective dose (ED50) of the transduction stage, increasing the apparent affinity. We study an example of inter-receptor interaction in order to account for possible compensatory effects of clustering and observe the parameter range in which such interactions slightly counterbalance the loss of activation of G. The membrane receptors’ spatial distribution affects the internal stages of signal amplification, suggesting a functional role for membrane domains and receptor clustering independently of proximity-induced receptor-receptor interactions.

  7. Influence of changes in external potassium and chloride ions on membrane potential and intracellular potassium ion activity in rabbit ventricular muscle.

    Science.gov (United States)

    Fozzard, H A; Lee, C O

    1976-04-01

    1. The membrane responses of rabbit papillary muscles to rapid changes in [K](o) and [Cl](o) were measured with open-tipped micropipettes and with closed micropipettes made from K-selective glass.2. The muscle cells behaved primarily as a K electrode, and responses to changes in [K](o) with constant [Cl](o) or with constant [K](o) x [Cl](o) were substantially the same.3. When [Cl](o) was changed at a constant [K](o) the membrane potentials changed rapidly and symmetrically by a small value and remained constant for 30 min.4. Measurement of potential with K(+)-selective micro-electrodes in these experiments showed no change in intracellular K activity. In addition to permitting calculation of K permeability, these measurements reassured us that the K(+)-selective electrodes were well insulated and not influenced by electrical shunts at the impalement site.5. Although the membrane response to changes in [Cl](o) was small, it was possible to calculate that the permeability ratio (P(Cl)/P(K)), was 0.11. The Cl and K conductances were about 0.015 mmho/cm(2) and 0.09 mmho/cm(2) respectively, resulting in a conductance ratio (g(Cl)/g(K)) of about 0.17.6. The time course of depolarization by increase in [K](o) was rapid (half-time 5 sec), but repolarization on return to lower [K](o) was much slower (half-time 50 sec). The depolarization time course was easily fitted by the potential change calculated by assuming the need for K diffusion into the extracellular spaces and taking account of the logarithmic relation between membrane potential and [K](o). These calculations did not fit the time course of repolarization, which was slowed in the fashion expected from an inward-rectifying membrane.7. The influence of [K](i) on membrane potential was investigated by changes in tonicity of the external solution. Hypotonic solution produced a change in intracellular K activity close to that produced by ideal water movement. However, in hypertonic solution, intracellular K activity

  8. The membrane-proximal external region of the human immunodeficiency virus type 1 envelope: dominant site of antibody neutralization and target for vaccine design.

    Science.gov (United States)

    Montero, Marinieve; van Houten, Nienke E; Wang, Xin; Scott, Jamie K

    2008-03-01

    Enormous efforts have been made to produce a protective vaccine against human immunodeficiency virus type 1; there has been little success. However, the identification of broadly neutralizing antibodies against epitopes on the highly conserved membrane-proximal external region (MPER) of the gp41 envelope protein has delineated this region as an attractive vaccine target. Furthermore, emerging structural information on the MPER has provided vaccine designers with new insights for building relevant immunogens. This review describes the current state of the field regarding (i) the structure and function of the gp41 MPER; (ii) the structure and binding mechanisms of the broadly neutralizing antibodies 2F5, 4E10, and Z13; and (iii) the development of an MPER-targeting vaccine. In addition, emerging approaches to vaccine design are presented.

  9. Vitrectomy with internal limiting membrane (ILM) peeling versus vitrectomy with no peeling for idiopathic full-thickness macular hole (FTMH)

    DEFF Research Database (Denmark)

    Spiteri Cornish, Kurt; Lois, Noemi; Scott, Neil;

    2013-01-01

    Several observational studies have suggested the potential benefit of internal limiting membrane (ILM) peeling to treat idiopathic full-thickness macular hole (FTMH). However, no strong evidence is available on the potential benefit(s) of this surgical manoeuvre and uncertainty remains among...... vitreoretinal surgeons about the indication for peeling the ILM, whether to use it in all cases or in long-standing and/or larger holes. ...

  10. External root resorption: Different etiologies explained from the composition of the human root-close periodontal membrane

    Directory of Open Access Journals (Sweden)

    Inger Kjaer

    2013-01-01

    Full Text Available Introduction: This paper summarizes different conditions, which have a well-known influence on the resorption of tooth roots. It also highlights factors important for individual susceptibility to root resorption. Furthermore, the paper focuses on idiopathic root resorption where the provoking factor is not known. The Hypothesis: The several different disturbances causing root resorption can be either orthodontically provoked or acquired by trauma, virus or congenital diseases. It is presumed that all these conditions lead to inflammatory processes in the three main tissue layers, comprising the peri-root sheet. Evaluation of the Hypothesis: This paper explains how different etiologies behind root resorption and how different phenotypic traits in root resorption can be understood from immunohistochemical studies of the human periodontal membrane close to the root and thus, gain a new understanding of the phenomenon of root resorption.

  11. A forward osmosis-membrane distillation hybrid process for direct sewer mining: system performance and limitations.

    Science.gov (United States)

    Xie, Ming; Nghiem, Long D; Price, William E; Elimelech, Menachem

    2013-01-01

    This study demonstrates the robustness and treatment capacity of a forward osmosis (FO)-membrane distillation (MD) hybrid system for small-scale decentralized sewer mining. A stable water flux was realized using a laboratory-scale FO-MD hybrid system operating continuously with raw sewage as the feed at water recovery up to 80%. The hybrid system also showed an excellent capacity for the removal of trace organic contaminants (TrOCs), with removal rates ranging from 91 to 98%. The results suggest that TrOC transport through the FO membrane is governed by "solute-membrane" interaction, whereas that through the MD membrane is strongly correlated to TrOC volatility. Concentrations of organic matter and TrOCs in the draw solution increased substantially as the water recovery increased. This accumulation of some contaminants in the draw solution is attributed to the difference in their rejection by the FO and MD systems. We demonstrate that granular activated carbon adsorption or ultraviolet oxidation could be used to prevent contaminant accumulation in the draw solution, resulting in near complete rejection (>99.5%) of TrOCs.

  12. Limiter

    Science.gov (United States)

    Cohen, S.A.; Hosea, J.C.; Timberlake, J.R.

    1984-10-19

    A limiter with a specially contoured front face is provided. The front face of the limiter (the plasma-side face) is flat with a central indentation. In addition, the limiter shape is cylindrically symmetric so that the limiter can be rotated for greater heat distribution. This limiter shape accommodates the various power scrape-off distances lambda p, which depend on the parallel velocity, V/sub parallel/, of the impacting particles.

  13. Internal Limiting Membrane Flap Techniques for the Repair of Large Macular Holes: a Short-Term Follow-up of Anatomical and Functional Outcomes.

    Science.gov (United States)

    Guber, J; Lang, C; Valmaggia, C

    2017-02-01

    Background To evaluate the technique of inverted internal limiting membrane (ILM) flaps for the management of large macular holes and autologous ILM free flaps for non-closing macular holes. Patients and methods All macular holes were treated with pars plana vitrectomy and dual blue assisted ILM flap technique. The inverted ILM flap was created as a primary procedure for large macular holes (diameter > 400 µm). On the other hand, the free ILM flap technique was used as a secondary procedure for non-closing macular holes after failed initial standard procedure. SD-OCT images were taken to assess the anatomical outcome of surgery, while best corrected visual acuity (BCVA) was used to evaluate the functional outcome during a 2-month follow-up. Results All patients underwent successful planned manipulation of the ILM flap. In seven patients/eyes, an inverted ILM flap was created, in three patients/eyes a free ILM flap translocation was performed. All patients achieved complete anatomical closure. Partial microstructural reconstruction, demonstrated on SD-OCT as restoration of the external limiting membrane and the ellipsoid zone, was observed in some cases as early as one month after surgery. Functionally, in comparison to baseline, most of the patients showed improvements in BCVA of 1 to 2 lines at the first postoperative follow-up visit. Conclusions Inverted ILM flaps for large macular holes and free flaps for non-closing macular holes appear to be a safe and effective approach, with favourable short-term anatomical and functional results.

  14. Translocation of the papillomavirus L2/vDNA complex across the limiting membrane requires the onset of mitosis.

    Science.gov (United States)

    Calton, Christine M; Bronnimann, Matthew P; Manson, Ariana R; Li, Shuaizhi; Chapman, Janice A; Suarez-Berumen, Marcela; Williamson, Tatum R; Molugu, Sudheer K; Bernal, Ricardo A; Campos, Samuel K

    2017-05-01

    The human papillomavirus type 16 (HPV16) L2 protein acts as a chaperone to ensure that the viral genome (vDNA) traffics from endosomes to the trans-Golgi network (TGN) and eventually the nucleus, where HPV replication occurs. En route to the nucleus, the L2/vDNA complex must translocate across limiting intracellular membranes. The details of this critical process remain poorly characterized. We have developed a system based on subcellular compartmentalization of the enzyme BirA and its cognate substrate to detect membrane translocation of L2-BirA from incoming virions. We find that L2 translocation requires transport to the TGN and is strictly dependent on entry into mitosis, coinciding with mitotic entry in synchronized cells. Cell cycle arrest causes retention of L2/vDNA at the TGN; only release and progression past G2/M enables translocation across the limiting membrane and subsequent infection. Microscopy of EdU-labeled vDNA reveals a rapid and dramatic shift in vDNA localization during early mitosis. At late G2/early prophase vDNA egresses from the TGN to a pericentriolar location, accumulating there through prometaphase where it begins to associate with condensed chromosomes. By metaphase and throughout anaphase the vDNA is seen bound to the mitotic chromosomes, ensuring distribution into both daughter nuclei. Mutations in a newly defined chromatin binding region of L2 potently blocked translocation, suggesting that translocation is dependent on chromatin binding during prometaphase. This represents the first time a virus has been shown to functionally couple the penetration of limiting membranes to cellular mitosis, explaining in part the tropism of HPV for mitotic basal keratinocytes.

  15. Prestin-driven cochlear amplification is not limited by the outer hair cell membrane time constant.

    Science.gov (United States)

    Johnson, Stuart L; Beurg, Maryline; Marcotti, Walter; Fettiplace, Robert

    2011-06-23

    Outer hair cells (OHCs) provide amplification in the mammalian cochlea using somatic force generation underpinned by voltage-dependent conformational changes of the motor protein prestin. However, prestin must be gated by changes in membrane potential on a cycle-by-cycle basis and the periodic component of the receptor potential may be greatly attenuated by low-pass filtering due to the OHC time constant (τ(m)), questioning the functional relevance of this mechanism. Here, we measured τ(m) from OHCs with a range of characteristic frequencies (CF) and found that, at physiological endolymphatic calcium concentrations, approximately half of the mechanotransducer (MT) channels are opened at rest, depolarizing the membrane potential to near -40 mV. The depolarized resting potential activates a voltage-dependent K+ conductance, thus minimizing τ(m) and expanding the membrane filter so there is little receptor potential attenuation at the cell's CF. These data suggest that minimal τ(m) filtering in vivo ensures optimal activation of prestin.

  16. Severe hypoxemia during veno-venous extracorporeal membrane oxygenation: exploring the limits of extracorporeal respiratory support

    Directory of Open Access Journals (Sweden)

    Liane Brescovici Nunes

    2014-03-01

    Full Text Available OBJECTIVE: Veno-venous extracorporeal oxygenation for respiratory support has emerged as a rescue alternative for patients with hypoxemia. However, in some patients with more severe lung injury, extracorporeal support fails to restore arterial oxygenation. Based on four clinical vignettes, the aims of this article were to describe the pathophysiology of this concerning problem and to discuss possibilities for hypoxemia resolution. METHODS: Considering the main reasons and rationale for hypoxemia during veno-venous extracorporeal membrane oxygenation, some possible bedside solutions must be considered: 1 optimization of extracorporeal membrane oxygenation blood flow; 2 identification of recirculation and cannula repositioning if necessary; 3 optimization of residual lung function and consideration of blood transfusion; 4 diagnosis of oxygenator dysfunction and consideration of its replacement; and finally 5 optimization of the ratio of extracorporeal membrane oxygenation blood flow to cardiac output, based on the reduction of cardiac output. CONCLUSION: Therefore, based on the pathophysiology of hypoxemia during veno-venous extracorporeal oxygenation support, we propose a stepwise approach to help guide specific interventions.

  17. Dependence of hemostasis indices on external environment nemperature in women with physiological pregnancy accompanied by limitation of liquid intake

    Directory of Open Access Journals (Sweden)

    Zhulina N.V.

    2011-12-01

    Full Text Available The research goal was to study the influence of extremely high temperatures on the hemostasis indices in patients with uncomplicated pregnancies with the concomitant limitation of liquid intake. The research results of hemostasis of pregnant women being hospitalized during the period of spring and summer in 2010 have been analyzed. The differences in the level of hypercoagulation changes of hemostasis in summer and spring have been found to be insignificant. In the platelet link hemostasis in summer of 2010, as compared to the spring, the increase of platelet aggregation and amount has been observed, with the exception of the third trimester, which is marked by the decrease of platelet amount. Hot seasons and liquid intake limitations make additional demands on hemostasis adaptive capacity, increasing the risk of thrombohemorrhagic complications

  18. Monetary valorization of the sanitary and environmental impacts of a nuclear accident: synthesis of ''ExternE'' studies, interests and limits of complementary developments; Valorisation monetaire des impacts sanitaires et environnementaux d'un accident nucleaire: synthese des etudes externe, interets et limites de developpements complementaires

    Energy Technology Data Exchange (ETDEWEB)

    Schieber, C.; Schneider, Th

    2002-09-01

    This document constitutes a synthesis of the various available methods for the monetary evaluation of the nuclear accidents impacts in order to reveal the already evaluated impacts, those which need complementary developments and those for which the monetary approach currently seems to come up against limits. It is based primarily on the approach realized by the ''ExternE'' project of the European Commission, consisting in the evaluation of the external costs of the nuclear energy industry. (A.L.B.)

  19. A model of photothermally induced damage to the retina during indocyanine-green-assisted peeling of the inner limiting membrane

    Science.gov (United States)

    Pini, Roberto; Toci, Guido; Rossi, Francesca; Giansanti, Fabrizio; Menchini, Ugo

    2004-07-01

    Intentional removal of the inner limiting membrane (ILM) in macular hole surgery is becoming a well-recognized procedure. It is usually performed with the assistance of Indocyanine Green (ICG), which selectively stains the membrane, in order to facilitate the visual control of surgery operations. In this theoretical study we investigate the possibility of heat damage to the retina being caused by the combination of ICG staining with the illumination provided by a standard light source for vitreo-retinal surgery, composed of a Xenon lamp and an optical fiber delivery system. For this purpose, we set up a bi-dimensional analytical model that describes light absorption and heat conduction in ICG-stained ILM and in retinal structures.

  20. Clinical and histological evaluation of large macular hole surgery using the inverted internal limiting membrane flap technique

    Science.gov (United States)

    Kase, Satoru; Saito, Wataru; Mori, Shohei; Saito, Michiyuki; Ando, Ryo; Dong, Zhenyu; Suzuki, Tomohiro; Noda, Kousuke; Ishida, Susumu

    2017-01-01

    Purpose The aims of this study were to analyze optical coherence tomography (OCT) imaging of large macular holes (MHs) treated with inverted internal limiting membrane (ILM) flap technique and to perform a histological examination of an ILM-like membrane tissue obtained during vitrectomy. Patients and methods This is a retrospective observational case study. Nine patients, comprising of five males and four females, showing large and myopic MHs, underwent pars plana vitrectomy (PPV) with inverted ILM flap technique assisted by brilliant blue G (BBG) staining. Ophthalmological findings including visual acuity and OCT were investigated based on medical records. Formalin-fixed paraffin-embedded tissue section of an ILM-like membrane was submitted for immunohistochemistry with glial fibrillary acidic protein (GFAP). Results ILM was clearly stained with BBG in eight patients, whereas the ILM in one case revealed no staining with BBG during PPV. Visual acuities improved to >0.2 LogMAR in six patients. The complete closure of MH following PPV with inverted ILM technique was eventually achieved in all patients determined by OCT imaging (100%). Only one patient showed recovery of ellipsoid zone and interdigitation zone following the surgery. Elongation of outer nuclear layer was noted in three eyes. The ILM-like membrane not stained with BBG histologically revealed an amorphous structure admixed with GFAP-positive mononuclear cell infiltration. Conclusion PPV with inverted ILM flap technique achieved 100% closure rates with favorable configuration at an initial surgery in large MHs. Our histopathological data also suggest that even BBG staining-negative membrane may be a useful material for autologous transplantation to the hole. PMID:28031697

  1. Differential regulation of two types of monogalactosyldiacylglylcerol synthase in membrane lipid remodeling under phosphate-limited conditions in sesame plants

    Directory of Open Access Journals (Sweden)

    Mie eShimojima

    2013-11-01

    Full Text Available Phosphate (Pi limitation causes drastic lipid remodeling in plant membranes. Glycolipids substitute for the phospholipids that are degraded, thereby supplying Pi needed for essential biological processes. Two major types of remodeling of membrane lipids occur in higher plants: whereas one involves an increase in the concentration of sulfoquinovosyldiacylglycerol in plastids to compensate for a decreased concentration of phosphatidylglycerol, the other involves digalactosyldiacylglycerol (DGDG synthesis in plastids and the export of DGDG to extraplastidial membranes to compensate for reduced abundances of phospholipids. Lipid remodeling depends on an adequate supply of monogalactosyldiacylglycerol (MGDG, which is a substrate that supports the elevated rate of DGDG synthesis that is induced by low Pi availability. Regulation of MGDG synthesis has been analyzed most extensively using the model plant Arabidopsis thaliana, although orthologous genes that encode putative MGDG synthases exist in photosynthetic organisms from bacteria to higher plants. We recently hypothesized that two types of MGDG synthase diverged after the appearance of seed plants. This divergence might have both enabled plants to adapt to a wide range of Pi availability in soils and contributed to the diversity of seed plants. In the work presented here, we found that membrane lipid remodeling also takes place in sesame, which is one of the most common traditional crops grown in Asia. We identified two types of MGDG synthase from sesame (encoded by SeMGD1 and SeMGD2 and analyzed their enzymatic properties. Our results show that both genes correspond to the Arabidopsis type-A and -B isoforms of MGDG synthase. Notably, whereas Pi limitation up-regulates only the gene encoding the type-B isoform of Arabidopsis, low Pi availability up-regulates the expression of both SeMGD1 and SeMGD2. We discuss the significance of the different responses to low Pi availability in sesame and

  2. A Meta-Analysis for Postoperative Complications in Tibial Plafond Fracture: Open Reduction and Internal Fixation Versus Limited Internal Fixation Combined With External Fixator.

    Science.gov (United States)

    Wang, Dong; Xiang, Jian-Ping; Chen, Xiao-Hu; Zhu, Qing-Tang

    2015-01-01

    The treatment of tibial plafond fractures is challenging to foot and ankle surgeons. Open reduction and internal fixation and limited internal fixation combined with an external fixator are 2 of the most commonly used methods of tibial plafond fracture repair. However, conclusions regarding the superior choice remain controversial. The present meta-analysis aimed to quantitatively compare the postoperative complications between open reduction and internal fixation and limited internal fixation combined with an external fixator for tibial plafond fractures. Nine studies with 498 fractures in 494 patients were included in the present study. The meta-analysis found no significant differences in bone healing complications (risk ratio [RR] 1.17, 95% confidence interval [CI] 0.68 to 2.01, p = .58], nonunion (RR 1.09, 95% CI 0.51 to 2.36, p = .82), malunion or delayed union (RR 1.24, 95% CI 0.57 to 2.69, p = .59), superficial (RR 1.56, 95% CI 0.43 to 5.61, p = .50) and deep (RR 1.89, 95% CI 0.62 to 5.80) infections, arthritis symptoms (RR 1.20, 95% CI 0.92 to 1.58, p = .18), or chronic osteomyelitis (RR 0.31, 95% CI 0.05 to 1.84, p = .20) between the 2 groups. Copyright © 2015 American College of Foot and Ankle Surgeons. Published by Elsevier Inc. All rights reserved.

  3. Trypan blue selective staining using whole blood for internal limiting membrane peeling during macular hole corrective surgery.

    Science.gov (United States)

    Lai, Chi-Chun; Chuang, Lan-Hsin; Wang, Nan-Kai; Yeung, Ling; Chen, Yen-Po; Hwang, Yih-Shiou; Chen, Kuan-Jen; Wu, Wei-Chi

    2009-01-01

    To prevent trypan blue (TB) retention and its potential toxicity by selectively staining the internal limiting membrane (ILM) with the aid of whole blood. Twenty-four consecutive patients with macular holes who underwent TB-assisted ILM peeling were enrolled. In the surgeries, autologous whole blood was applied to cover the macular hole, and only the area selectively used for TB staining was exposed. Trypan blue solution (0.75 mg/mL, after being diluted with 5% glucose) was used to stain the exposed macular area in the fluid-filled vitreous cavity. The stained ILM was then completely removed. Twenty-four macular holes were studied. The ILMs were selectively stained by trypan blue and then removed completely. No visible dye remained on the retina after peeling. The macular holes were closed in 22 eyes (92%) after a single surgery. The mean best-corrected visual acuity improved from 20/140 to 20/62 after surgery. In addition, no fundus changes were observed during the follow-up period. Selective staining of ILM during TB-assisted membrane peeling could be achieved with whole blood as the adjuvant. Complete removal of stained membranes can prevent TB retention and may further reduce toxicity on retinal pigment epithelium and retina.

  4. SPECTRAL DOMAIN OPTICAL COHERENCE TOMOGRAPHY-BASED MICROSTRUCTURAL ANALYSIS OF RETINAL ARCHITECTURE POST INTERNAL LIMITING MEMBRANE PEELING FOR SURGERY OF IDIOPATHIC MACULAR HOLE REPAIR.

    Science.gov (United States)

    Modi, Aditya; Giridhar, Anantharaman; Gopalakrishnan, Mahesh

    2017-02-01

    Spectral domain optical coherence tomography-based analysis of retinal architecture after internal limiting membrane peeling for macular hole surgery. Prospective, interventional study. Fifty eyes underwent the surgical procedure with minimum internal limiting membrane peel of 3 mm diameter. Automatic segmentation software was used to assess individual layers preoperatively and postoperatively, 1.5 millimeters medial and lateral to fovea at 3 months postoperative visit. Main outcome measures were final central macular thickness and variation in individual retinal layer thickness. Mean central macular thickness postoperatively was 201 microns. Retinal thickening was observed, 1.5 mm medial to fovea (P Internal limiting membrane peel is associated with significant alteration in inner retinal architecture, especially in ganglion cell layer, which can adversely influence functional outcome of the surgery and makes it imperative to avoid peeling internal limiting membrane over a larger surface area.

  5. Inverted Internal Limiting Membrane Flap Technique for Repair of Large Macular Holes: A Short-term Follow-up of Anatomical and Functional Outcomes

    Institute of Scientific and Technical Information of China (English)

    Zhe Chen; Chan Zhao; Jun-Jie Ye; Xu-Qian Wang; Rui-Fang Sui

    2016-01-01

    Background:Inverted internal limiting membrane (ILM) flap technique has recently been reported in a limited number of studies as an effective surgical technique for the management of large macular holes (MHs) with fair MH closure rates as well as gains in visual acuity.In the current study,longitudinal changes in multi-focal electroretinogram (mfERG) responses,best-corrected visual acuity (BCVA) and spectral-domain optical coherence tomography (SD-OCT) were evaluated in eyes with large MHs managed by this technique.Methods:A prospective noncontrolled interventional study of eight patients (eight eyes) with large MHs (minimum diameter >400 μm) was conducted.All MHs were treated with pars plana vitrectomy and indocyanine green-assisted inverted ILM flap technique.SD-OCT images were used to assess the anatomical outcomes of surgery while BCVA and mfERG were used to evaluate the functional outcomes during a 3-month follow-up.Results:All patients underwent successful intended manipulation and translocation of the ILM flap without flap dislocation and achieved complete anatomical closure.Partial microstructural reconstruction,demonstrated on SD-OCT as restoration of the external limiting membrane and the ellipsoid zone,was observed in all cases as early as 1 month after surgery.Functionally,as compared to baseline,all patients showed improvements in BCVA and all but one in mfERG response during follow-up.However,Pearson's test revealed no significant correlations between BCVA and mfERG responses of the fovea and of the macular area at each evaluation time point.Conclusions:Inverted ILM flap technique appeares to be a safe and effective approach for the management of large idiopathic MHs with favorable short-term anatomical and functional results.Postoperative reconstruction of the microstructure generally shows good consistency with improvements in both BCVA and mfERG response,of which the latter might be a supplement for the former in postoperative functional follow-up.

  6. N-terminal residues of an HIV-1 gp41 membrane-proximal external region antigen influence broadly neutralizing 2F5-like antibodies

    Institute of Scientific and Technical Information of China (English)

    Dezhi Li; Jie Liu; Li Zhang; Tianshu Xu; Junheng Chen; Liping Wang; Qi Zhao

    2015-01-01

    The Human immunodeficiency virus type 1(HIV-1) gp41 membrane proximal external region(MPER) is targeted by broadly neutralizing antibodies(e.g. 2F5, 4E10, Z13 e and m66.6), which makes this region a promising target for vaccine design. One strategy to elicit neutralizing antibodies against the MPER epitope is to design peptide immunogens mimicking neutralization structures. To probe 2F5-like neutralizing antibodies, two yeast-displayed antibody libraries from peripheral blood mononuclear cells from a HIV-1 patient were screened against the 2F5 epitope peptide SP62. Two 2F5-like antibodies were identified that specifically recognized SP62. However,these antibodies only weakly neutralized HIV-1 primary isolates. The epitopes recognized by these two 2F5-like antibodies include not only the 2F5 epitope(amino acids(aa) 662–667 in the MPER)but also several other residues(aa 652–655) locating at the N-terminus in SP62. Experimental results suggest that residues of SP62 adjacent to the 2F5 epitope influence the response of broadly neutralizing 2F5-like antibodies in vaccination. Our findings may aid the design of vaccine immunogens and development of therapeutics against HIV-1 infection.

  7. N-terminal residues of an HIV-1 gp41 membrane-proximal external region antigen influence broadly neutralizing 2F5-like antibodies.

    Science.gov (United States)

    Li, Dezhi; Liu, Jie; Zhang, Li; Xu, Tianshu; Chen, Junheng; Wang, Liping; Zhao, Qi

    2015-12-01

    The Human immunodeficiency virus type 1 (HIV-1) gp41 membrane proximal external region (MPER) is targeted by broadly neutralizing antibodies (e.g. 2F5, 4E10, Z13e and m66.6), which makes this region a promising target for vaccine design. One strategy to elicit neutralizing antibodies against the MPER epitope is to design peptide immunogens mimicking neutralization structures. To probe 2F5-like neutralizing antibodies, two yeast-displayed antibody libraries from peripheral blood mononuclear cells from a HIV-1 patient were screened against the 2F5 epitope peptide SP62. Two 2F5-like antibodies were identified that specifically recognized SP62. However, these antibodies only weakly neutralized HIV-1 primary isolates. The epitopes recognized by these two 2F5-like antibodies include not only the 2F5 epitope (amino acids (aa) 662-667 in the MPER) but also several other residues (aa 652-655) locating at the N-terminus in SP62. Experimental results suggest that residues of SP62 adjacent to the 2F5 epitope influence the response of broadly neutralizing 2F5-like antibodies in vaccination. Our findings may aid the design of vaccine immunogens and development of therapeutics against HIV-1 infection.

  8. Osmotic tolerance limits and effects of cryoprotectants on the motility, plasma membrane integrity and acrosomal integrity of rat sperm.

    Science.gov (United States)

    Si, Wei; Benson, James D; Men, Hongsheng; Critser, John K

    2006-12-01

    Osmotic stress is an important factor that can result in cell damage during cryopreservation. The objectives of this study were to determine: (1) isosmotic sperm cell volume; (2) osmotically inactive volume; (3) osmotic tolerance limits of rat sperm; and (4) the effects of addition and removal of glycerol (Gly), ethylene glycol (EG), propylene glycol (PG) or dimethyl sulfoxide (Me(2)SO) on rat sperm function. Sperm from Fischer 344 and Sprague-Dawley rats were used in this study. An electronic particle counter was used to measure the cell volume of rat sperm. Computer-assisted sperm motility analysis and flow-cytometric analysis were used to assess sperm motility, plasma membrane and acrosomal integrity. The isosmotic sperm cell volumes of the two strains were 37.0+/-0.1 and 36.2+/-0.2 microm(3), respectively. Rat sperm behaved as linear osmometers from 260 to 450 mOsm, and the osmotically inactive sperm volumes of the two strains were 79.8+/-1.5% and 81.4+/-2.2%, respectively. Rat sperm have very limited osmotic tolerances. The sperm motility and the sperm plasma membranes of both strains were sensitive to anisosmotic treatments, but the acrosomes of both strains were more sensitive to hyposmotic than hyperosmotic conditions. The one-step addition and removal of Me(2)SO showed the most deleterious effect on rat sperm motility, plasma membrane integrity, and acrosomal integrity among the four cryoprotectants. These data characterizing rat sperm osmotic behavior, osmotic and cryoprotectant tolerance will be used to design cryopreservation protocols for rat sperm.

  9. Pushing desalination recovery to the maximum limit: Membrane and thermal processes integration

    KAUST Repository

    Shahzad, Muhammad Wakil

    2017-05-05

    The economics of seawater desalination processes has been continuously improving as a result of desalination market expansion. Presently, reverse osmosis (RO) processes are leading in global desalination with 53% share followed by thermally driven technologies 33%, but in Gulf Cooperation Council (GCC) countries their shares are 42% and 56% respectively due to severe feed water quality. In RO processes, intake, pretreatment and brine disposal cost 25% of total desalination cost at 30–35% recovery. We proposed a tri-hybrid system to enhance overall recovery up to 81%. The conditioned brine leaving from RO processes supplied to proposed multi-evaporator adsorption cycle driven by low temperature industrial waste heat sources or solar energy. RO membrane simulation has been performed using WinFlow and IMSDesign commercial softwares developed by GE and Nitto. Detailed mathematical model of overall system is developed and simulation has been conducted in FORTRAN. The final brine reject concentration from tri-hybrid cycle can vary from 166,000ppm to 222,000ppm if RO retentate concentration varies from 45,000ppm to 60,000ppm. We also conducted economic analysis and showed that the proposed tri-hybrid cycle can achieve highest recovery, 81%, and lowest energy consumption, 1.76kWhelec/m3, for desalination reported in the literature up till now.

  10. Effect of external resonant fields and limiter biasing on hard X-ray intensity and mirnov oscillations in IR-T1 Tokamak

    Science.gov (United States)

    Ghanbari, K.; Ghoranneviss, M.; Elahi, A. Salar

    2015-01-01

    Runaway electrons in tokamaks can cause serious damage to the first wall of the reactor and decrease its life time. Also, hard x-ray emission generated from high energy runaway electrons lead to the plasma energy loss. Therefore, suggesting methods to minimize runaway electron in tokamaks are very important. Applying external resonant field is one of the methods for controlling the Magneto Hydrodynamic (MHD) activity. Relation between the MHD activity and runaway electrons has already been studied (Jaspers et al. 1994; Ghanbari et al. 2012) Jaspers, R., et al. 1994 Phys. Rev. Lett. 72, 4093; Ghanbari, M. R., et al. 2012a Phys. Scr. 83, 055501. Present study attempts to investigate the effects of limiter biasing and Resonant Helical magnetic Field (RHF) on the generation of runaway electrons. For this purpose, plasma parameters such as plasma current, MHD oscillation, loop voltage, emitted hard x-ray intensity, Halpha impurity, safety factor in the presence and absence of external fields, were measured. Frequency activity was investigated with FFT analysis. The results show that applying resonant fields can control the MHD activity, and then hard x-ray emitted from the runaway electrons.

  11. Testing the limits of rational design by engineering pH sensitivity into membrane-active peptides.

    Science.gov (United States)

    Wiedman, Gregory; Wimley, William C; Hristova, Kalina

    2015-04-01

    In this work, we sought to rationally design membrane-active peptides that are triggered by low pH to form macromolecular-sized pores in lipid bilayers. Such peptides could have broad utility in biotechnology and in nanomedicine as cancer therapeutics or drug delivery vehicles that promote release of macromolecules from endosomes. Our approach to rational design was to combine the properties of a pH-independent peptide, MelP5, which forms large pores allowing passage of macromolecules, with the properties of two pH-dependent membrane-active peptides, pHlip and GALA. We created two hybrid sequences, MelP5_Δ4 and MelP5_Δ6, by using the distribution of acidic residues on pHlip and GALA as a guide to insert acidic amino acids into the amphipathic helix of MelP5. We show that the new peptides bind to lipid bilayers and acquire secondary structure in a pH-dependent manner. The peptides also destabilize bilayers in a pH-dependent manner, such that lipid vesicles release the small molecules ANTS/DPX at low pH only. Thus, we were successful in designing pH-triggered pore-forming peptides. However, no macromolecular release was observed under any conditions. Therefore, we abolished the unique macromolecular poration properties of MelP5 by introducing pH sensitivity into its sequence. We conclude that the properties of pHlip, GALA, and MelP5 are additive, but only partially so. We propose that this lack of additivity is a limitation in the rational design of novel membrane-active peptides, and that high-throughput approaches to discovery will be critical for continued progress in the field.

  12. Functional, non-clonal IgMa-restricted B cell receptor interactions with the HIV-1 envelope gp41 membrane proximal external region.

    Directory of Open Access Journals (Sweden)

    Laurent Verkoczy

    Full Text Available The membrane proximal external region (MPER of HIV-1 gp41 has several features that make it an attractive antibody-based vaccine target, but eliciting an effective gp41 MPER-specific protective antibody response remains elusive. One fundamental issue is whether the failure to make gp41 MPER-specific broadly neutralizing antibodies like 2F5 and 4E10 is due to structural constraints with the gp41 MPER, or alternatively, if gp41 MPER epitope-specific B cells are lost to immunological tolerance. An equally important question is how B cells interact with, and respond to, the gp41 MPER epitope, including whether they engage this epitope in a non-canonical manner i.e., by non-paratopic recognition via B cell receptors (BCR. To begin understanding how B cells engage the gp41 MPER, we characterized B cell-gp41 MPER interactions in BALB/c and C57BL/6 mice. Surprisingly, we found that a significant (approximately 7% fraction of splenic B cells from BALB/c, but not C57BL/6 mice, bound the gp41 MPER via their BCRs. This strain-specific binding was concentrated in IgM(hi subsets, including marginal zone and peritoneal B1 B cells, and correlated with enriched fractions (approximately 15% of gp41 MPER-specific IgM secreted by in vitro-activated splenic B cells. Analysis of Igh(a (BALB/c and Igh(b (C57BL/6 congenic mice demonstrated that gp41 MPER binding was controlled by determinants of the Igh(a locus. Mapping of MPER gp41 interactions with IgM(a identified MPER residues distinct from those to which mAb 2F5 binds and demonstrated the requirement of Fc C(H regions. Importantly, gp41 MPER ligation produced detectable BCR-proximal signaling events, suggesting that interactions between gp41 MPER and IgM(a determinants may elicit partial B cell activation. These data suggest that low avidity, non-paratopic interactions between the gp41 MPER and membrane Ig on naïve B cells may interfere with or divert bnAb responses.

  13. Generation of Long-Lived Bone Marrow Plasma Cells Secreting Antibodies Specific for the HIV-1 gp41 Membrane-Proximal External Region in the Absence of Polyreactivity

    Science.gov (United States)

    Donius, Luke R.; Cheng, Yuxing; Choi, Jaewon; Sun, Zhen-Yu J.; Hanson, Melissa; Zhang, Michael; Gierahn, Todd M.; Marquez, Susanna; Uduman, Mohammed; Kleinstein, Steven H.; Irvine, Darrell; Love, J. Christopher; Reinherz, Ellis L.

    2016-01-01

    ABSTRACT An effective preventive vaccine is highly sought after in order to stem the current HIV-1 pandemic. Both conservation of contiguous gp41 membrane-proximal external region (MPER) amino acid sequences across HIV-1 clades and the ability of anti-MPER broadly neutralizing antibodies (BNAbs) to block viral hemifusion/fusion establish the MPER as a prime vaccination target. In earlier studies, we described the development of an MPER vaccine formulation that takes advantage of liposomes to array the MPER on a lipid bilayer surface, paralleling its native configuration on the virus membrane while also incorporating molecular adjuvant and CD4 T cell epitope cargo. Here we demonstrate that several immunizations with MPER/liposomes induce high levels of bone marrow long-lived plasma cell (LLPC) antibody production. Single-cell immunoglobulin gene retrieval analysis shows that these plasma cells are derived from a germ line repertoire of B cells with a diverse representation of immunoglobulin genes, exhibiting antigen-driven positive selection. Characterization of LLPC recombinant monoclonal antibodies (rMAbs) indicates that antigen recognition is achieved through convergence on a common epitopic focus by utilizing various complementarity-determining region H3 (CDRH3) lengths. Importantly, the vast majority of rMAbs produced from these cells lack polyreactivity yet manifest antigen specificity in the context of lipids, shaping MPER-specific paratopes through selective pressure. Taken together, these findings demonstrate that the MPER is a vaccine target with minimal risk of generating off-target autoimmunity. IMPORTANCE A useful vaccine must generate desired long-term, antigen-specific antibody responses devoid of polyreactivity or autoreactivity. The common polyreactive features of some HIV-1 BNAbs have raised concern about elicitation of anti-MPER antibodies. Utilizing single-LLPC repertoire analysis and biophysical characterization of anti-MPER rMAbs, we show that

  14. Spatial distribution and dynamics of proton conductivity in fuel cell membranes: potential and limitations of electrochemical atomic force microscopy measurements.

    Science.gov (United States)

    Aleksandrova, E; Hink, S; Hiesgen, R; Roduner, E

    2011-06-15

    The proton conductivity of a Nafion 112 membrane is measured with a high spatial resolution using electrochemical atomic force microscopy. Image analysis reveals an inhomogeneous conductivity distribution which is attributed to the limited connectivity of hydrophilic domains. This information relates to the micro-morphology which is due to phase separation of the hydrophobic polymer backbone and the hydrophilic pendant groups. The direct images relate to a different length scale and are complementary to the x-ray diffraction investigations which provide only average information. Furthermore, the measured current values reveal an interesting correlation with the size of the conductive areas. A bimodal conductivity distribution suggests that there are different mechanisms which contribute to the proton current in Nafion. Additionally, time dependence in local conductivity is found and interpreted in terms of redistribution of water in the membrane. A statistical analysis of the current distribution is performed and compared with theoretical simulations. Evidence is found for the existence of a critical current density. On a timescale of seconds the response of the conductive network is probed by applying voltage steps to the atomic force microscope tip.

  15. Plasma-membrane hyperpolarization diminishes the cation efflux via Nha1 antiporter and Ena ATPase under potassium-limiting conditions.

    Science.gov (United States)

    Zahrádka, Jaromír; Sychrová, Hana

    2012-06-01

    Saccharomyces cerevisiae extrudes K(+) cations even when potassium is only present in scarce amounts in the environment. Lost potassium is taken up by the Trk1 and Trk2 uptake systems. If the Trk transporters are absent or nonfunctional, the efflux of potassium is significantly diminished. A series of experiments with strains lacking various combinations of potassium efflux and uptake systems revealed that all three potassium-exporting systems the Nha1 antiporter, Ena ATPase and Tok1 channel contribute to potassium homeostasis and are active upon potassium limitation in wild-type cells. In trk1Δ trk2Δ mutants, the potassium efflux via potassium exporters Nha1 and Ena1 is diminished and can be restored either by the expression of TRK1 or deletion of TOK1. In both cases, the relative hyperpolarization of trk1Δ trk2Δ cells is decreased. Thus, it is the plasma-membrane potential which serves as the common mechanism regulating the activity of K(+) exporting systems. There is a continuous uptake and efflux of potassium in yeast cells to regulate their membrane potential and thereby other physiological parameters, and the cells are able to quickly and efficiently compensate for a malfunction of potassium transport in one direction by diminishing the transport in the other direction.

  16. Improving the detection limits of antispasmodic drugs electrodes by using modified membrane sensors with inner solid contact.

    Science.gov (United States)

    Ibrahim, Hosny; Issa, Y M; Abu-Shawish, Hazem M

    2007-05-09

    Three coated wire electrodes (CWEs) for the antispasmodic drugs; dicyclomine (Dc), mebeverine (Mv) and drotaverine (Dv) hydrochlorides were developed. Each electrode based on ion-associate of a heteropoly anion with the drug cation incorporated in membrane sensor modified with graphite and deposited on silver internal solid contact. The influence of addition of graphite to the membranes and the type of the internal solid contact on the potentiometric responses of the electrodes was investigated. The characteristics of the new electrodes were compared to the characteristics of previously reported traditional liquid inner contact electrodes of the same drugs. The lower detection limits of the proposed electrodes were somewhat better than those observed with the corresponding liquid contact ISEs and reached (1.2-2.0)x10(-7)M. The potentiometric selectivity of the CWEs revealed a significant improvement and much faster response times compared to the liquid contact ISEs. The practical utility of each electrode has been demonstrated by using it successfully in potentiometric determination of its respective drug in pharmaceutical preparations both in batch and flow injection conditions. Each electrode was also used as an indicator electrode in the potentiometric titration of the drug against standard silicotungstic acid and in potentiometric determination of the drug concentration in urine samples.

  17. Students' Understanding of External Representations of the Potassium Ion Channel Protein, Part I: Affordances and Limitations of Ribbon Diagrams, Vines, and Hydrophobic/Polar Representations

    Science.gov (United States)

    Harle, Marissa; Towns, Marcy H.

    2012-01-01

    Research on external representations in biochemistry has uncovered student difficulties in comprehending and interpreting external representations. This project focuses on students' understanding of three external representations of the potassium ion channel protein. This is part I of a two-part study, which focuses on the affordances and…

  18. Immunogens Modeling a Fusion-Intermediate Conformation of gp41 Elicit Antibodies to the Membrane Proximal External Region of the HIV Envelope Glycoprotein.

    Directory of Open Access Journals (Sweden)

    Russell Vassell

    Full Text Available The membrane proximal external region (MPER of the gp41 subunit of the HIV-1 envelope glycoprotein (Env contains determinants for broadly neutralizing antibodies and has remained an important focus of vaccine design. However, creating an immunogen that elicits broadly neutralizing antibodies to this region has proven difficult in part due to the relative inaccessibility of the MPER in the native conformation of Env. Here, we describe the antigenicity and immunogenicity of a panel of oligomeric gp41 immunogens designed to model a fusion-intermediate conformation of Env in order to enhance MPER exposure in a relevant conformation. The immunogens contain segments of the gp41 N- and C-heptad repeats to mimic a trapped intermediate, followed by the MPER, with variations that include different N-heptad lengths, insertion of extra epitopes, and varying C-termini. These well-characterized immunogens were evaluated in two different immunization protocols involving gp41 and gp140 proteins, gp41 and gp160 DNA primes, and different immunization schedules and adjuvants. We found that the immunogens designed to reduce extension of helical structure into the MPER elicited the highest MPER antibody binding titers, but these antibodies lacked neutralizing activity. The gp41 protein immunogens also elicited higher MPER titers than the gp140 protein immunogen. In prime-boost studies, the best MPER responses were seen in the groups that received DNA priming with gp41 vectors followed by gp41 protein boosts. Finally, although titers to the entire protein immunogen were similar in the two immunization protocols, MPER-specific titers differed, suggesting that the immunization route, schedule, dose, or adjuvant may differentially influence MPER immunogenicity. These findings inform the design of future MPER immunogens and immunization protocols.

  19. Removal of spermatozoa with externalized phosphatidylserine from sperm preparation in human assisted medical procreation: effects on viability, motility and mitochondrial membrane potential

    Directory of Open Access Journals (Sweden)

    de Agostini Ariane

    2009-01-01

    Full Text Available Abstract Background Externalization of phosphatidylserine (EPS occurs in apoptotic-like spermatozoa and could be used to remove them from sperm preparations to enhance sperm quality for assisted medical procreation. We first characterized EPS in sperms from infertile patients in terms of frequency of EPS spermatozoa as well as localization of phosphatidylserine (PS on spermatozoa. Subsequently, we determined the impact of depleting EPS spermatozoa on sperm quality. Methods EPS were visualized by fluorescently-labeled annexin V binding assay. Double staining with annexin V and Hoechst differentiates apoptotic from necrotic spermatozoa. We used magnetic-activated cell sorting using annexin V-conjugated microbeads (MACS-ANMB technique to remove EPS spermatozoa from sperm prepared by density gradient centrifugation (DGC. The impact of this technique on sperm quality was evaluated by measuring progressive motility, viability, and the integrity of the mitochondrial membrane potential (MMP by Rhodamine 123. Results Mean percentages of EPS spermatozoa were 14% in DGC sperm. Four subpopulations of spermatozoa were identified: 70% alive, 3% early apoptotic, 16% necrotic and 11% late apoptotic or necrotic. PS were localized on head and/or midpiece or on the whole spermatozoa. MACS efficiently eliminates EPS spermatozoa. MACS combined with DGC allows a mean reduction of 70% in EPS and of 60% in MMP-disrupted spermatozoa with a mean increase of 50% in sperm survival at 24 h. Conclusion Human ejaculates contain EPS spermatozoa which can mostly be eliminated by DGC plus MACS resulting in improved sperm long term viability, motility and MMP integrity. EPS may be used as an indicator of sperm quality and removal of EPS spermatozoa may enhance fertility potential in assisted medical procreation.

  20. Value of internal limiting membrane peeling in surgery for idiopathic macular hole and the correlation between function and retinal morphology

    DEFF Research Database (Denmark)

    Christensen, Ulrik Correll

    2009-01-01

    , but during the past decade focus has especially been on internal limiting membrane (ILM) peeling as adjuvant therapy for increasing closure rates. With increasing use of ILM peeling and indocyanine green (ICG) staining, which is used for specific visualization of the ILM, concerns about the safety...... rate than surgery without ILM peeling (95% versus 45%). The overall functional results confirm that surgery for macular hole generally leads to favourable visual results, with two-thirds of eyes regaining reading vision (>or=20/40). Macular hole surgery can be considered a safe procedure with a low...... incidence of sight-threatening adverse events; the retinal detachment rate was 2.2%. Visual outcomes in eyes with primary hole closure were not significantly different between the intervention groups; however, for the stage 2 subgroup with primary macular hole closure, there was a trend towards a better...

  1. Role of Tractional Forces and Internal Limiting Membrane in Macular Hole Formation: Insights from Intraoperative Optical Coherence Tomography

    Directory of Open Access Journals (Sweden)

    Elad Moisseiev

    2016-07-01

    Full Text Available We report the case of a 69-year-old patient who underwent vitrectomy for vitreomacular traction (VMT and developed a postoperative macular hole that was observed 1 week after surgery. The hole did not close by in-office fluid-gas exchange alone, but was achieved after repeat surgery with internal limiting membrane (ILM peeling. Intraoperative OCT (iOCT images from the first surgery revealed an occult macular hole that formed after VMT release. We discuss how iOCT findings provide insight into the role of the ILM in macular hole formation and emphasize the importance of carefully inspecting iOCT images in real time to avoid missing small but important findings.

  2. Internal limiting membrane peeling and gas tamponade for myopic foveoschisis: a systematic review and meta-analysis.

    Science.gov (United States)

    Meng, Bo; Zhao, Lu; Yin, Yi; Li, Hongyang; Wang, Xiaolei; Yang, Xiufen; You, Ran; Wang, Jialin; Zhang, Youjing; Wang, Hui; Du, Ran; Wang, Ningli; Zhan, Siyan; Wang, Yanling

    2017-09-08

    Myopic foveoschisis (MF) is among the leading causes of visual loss in high myopia. However, it remains controversial whether internal limiting membrane (ILM) peeling or gas tamponade is necessary treatment option for MF. PubMed, EMBASE, CBM, CNKI, WANFANG DATA and VIP databases were systematically reviewed. Outcome indicators were myopic foveoschisis resolution rate, visual acuity improvement and postoperative complications. Nine studies that included 239 eyes were selected. The proportion of resolution of foveoschisis was higher in ILM peeling group than non-ILM peeling group (OR = 2.15, 95% CI: 1.06-4.35; P = 0.03). The proportion of postoperative complications was higher in Tamponade group than non-Tamponade group (OR = 10.81, 95% CI: 1.26-93.02; P = 0.03). However, the proportion of visual acuity improvement (OR = 1.63, 95% CI: 0.56-4.80; P = 0.37) between ILM peeling group and non-ILM peeling group and the proportion of resolution of foveoschisis (OR = 1.80, 95% CI: 0.76-4.28; P = 0.18) between Tamponade group and non-Tamponade group were similar. Vitrectomy with internal limiting membrane peeling could contribute to better resolution of myopic foveoschisis than non-peeling, however it does not significantly influence the proportion of visual acuity improvement and postoperative complications. Vitrectomy with gas tamponade is associated with more complications than non-tamponade and does not significantly influence the proportion of visual acuity improvement and resolution of myopic foveoschisis.

  3. Effect of ceramic membrane channel geometry and uniform transmembrane pressure on limiting flux and serum protein removal during skim milk microfiltration.

    Science.gov (United States)

    Adams, Michael C; Hurt, Emily E; Barbano, David M

    2015-11-01

    Our objectives were to determine the effects of a ceramic microfiltration (MF) membrane's retentate flow channel geometry (round or diamond-shaped) and uniform transmembrane pressure (UTP) on limiting flux (LF) and serum protein (SP) removal during skim milk MF at a temperature of 50°C, a retentate protein concentration of 8.5%, and an average cross-flow velocity of 7 m·s(-1). Performance of membranes with round and diamond flow channels was compared in UTP mode. Performance of the membrane with round flow channels was compared with and without UTP. Using UTP with round flow channel MF membranes increased the LF by 5% when compared with not using UTP, but SP removal was not affected by the use of UTP. Using membranes with round channels instead of diamond-shaped channels in UTP mode increased the LF by 24%. This increase was associated with a 25% increase in Reynolds number and can be explained by lower shear at the vertices of the diamond-shaped channel's surface. The SP removal factor of the diamond channel system was higher than the SP removal factor of the round channel system below the LF. However, the diamond channel system passed more casein into the MF permeate than the round channel system. Because only one batch of each membrane was tested in our study, it was not possible to determine if the differences in protein rejection between channel geometries were due to the membrane design or random manufacturing variation. Despite the lower LF of the diamond channel system, the 47% increase in membrane module surface area of the diamond channel system produced a modular permeate removal rate that was at least 19% higher than the round channel system. Consequently, using diamond channel membranes instead of round channel membranes could reduce some of the costs associated with ceramic MF of skim milk if fewer membrane modules could be used to attain the required membrane area.

  4. Comparisons of external fixator combined with limited internal fixation and open reduction and internal fixation for Sanders type 2 calcaneal fractures: Finite element analysis and clinical outcome.

    Science.gov (United States)

    Pan, M; Chai, L; Xue, F; Ding, L; Tang, G; Lv, B

    2017-07-01

    The aim of this study was to compare the biomechanical stability and clinical outcome of external fixator combined with limited internal fixation (EFLIF) and open reduction and internal fixation (ORIF) in treating Sanders type 2 calcaneal fractures. Two types of fixation systems were selected for finite element analysis and a dual cohort study. Two fixation systems were simulated to fix the fracture in a finite element model. The relative displacement and stress distribution were analysed and compared. A total of 71 consecutive patients with closed Sanders type 2 calcaneal fractures were enrolled and divided into two groups according to the treatment to which they chose: the EFLIF group and the ORIF group. The radiological and clinical outcomes were evaluated and compared. The relative displacement of the EFLIF was less than that of the plate (0.1363 mm to 0.1808 mm). The highest von Mises stress value on the plate was 33% higher than that on the EFLIF. A normal restoration of the Böhler angle was achieved in both groups. No significant difference was found in the clinical outcome on the American Orthopedic Foot and Ankle Society Ankle Hindfoot Scale, or on the Visual Analogue Scale between the two groups (p > 0.05). Wound complications were more common in those who were treated with ORIF (p = 0.028). Both EFLIF and ORIF systems were tested to 160 N without failure, showing the new construct to be mechanically safe to use. Both EFLIF and ORIF could be effective in treating Sanders type 2 calcaneal fractures. The EFLIF may be superior to ORIF in achieving biomechanical stability and less blood loss, shorter surgical time and hospital stay, and fewer wound complications.Cite this article: M. Pan, L. Chai, F. Xue, L. Ding, G. Tang, B. Lv. Comparisons of external fixator combined with limited internal fixation and open reduction and internal fixation for Sanders type 2 calcaneal fractures: Finite element analysis and clinical outcome. Bone Joint Res 2017

  5. Outcomes of 23-gauge pars plana vitrectomy and internal limiting membrane peeling with brilliant blue in macular hole

    Directory of Open Access Journals (Sweden)

    Nohutcu A

    2011-08-01

    Full Text Available Huseyin Sanisoglu1, Mehmet Sahin Sevim1, Betul Aktas1, Semra Sevim2, Ahmet Nohutcu11Haydarpasa Numune Education and Research Hospital, Department of Ophthalmology, 2Uskudar State Hospital, Eye Clinic, Istanbul, TurkeyPurpose: The evaluation of anatomic and visual outcomes in macular hole cases treated with internal limiting membrane (ILM peeling, brilliant blue (BB, and 23-gauge pars plana vitrectomy (PPV.Materials and methods: Fifty eyes of 48 patients who presented between July 2007 and December 2009 with the diagnosis of stage 2, 3, or 4 macular holes according to Gass Classification who had undergone PPV and ILM peeling were included in this study. Pre- and postoperative macular examinations were assessed with spectral-domain optical coherence tomography. 23 G sutureless PPV and ILM peeling with BB was performed on all patients.Results: The mean age of patients was 63.34 ± 9.6 years. Stage 2 macular hole was determined in 17 eyes (34%, stage 3 in 24 eyes (48%, and stage 4 in 9 eyes (18%. The mean follow-up time was 13.6 ± 1.09 months. Anatomic closure was detected in 46/50 eyes (92%, whereas, in four cases, macular hole persisted and a second operation was not required due to subretinal fluid drainage. At follow-up after 2 months, persistant macular hole was detected in one case and it was closed with reoperation. At 12 months, an increase in visual acuity in 41 eyes was observed, while it remained at the same level in six eyes. In three eyes visual acuity decreased. There was a postoperative statistically significant increase in visual acuity in stage 2 and 3 cases (P < 0.05, however, no increase in visual acuity in stage 4 cases was observed.Conclusion: PPV and ILM peeling in stage 2, 3, and 4 macular hole cases provide successful anatomic outcomes, however, in delayed cases, due to photoreceptor loss, it has no effect on functional recovery. BB, used for clarity of ILM, may be beneficial due to its low retinal toxicity.Keywords: macular

  6. Internal limiting membrane layer visualization and vitreoretinal surgery guidance using a common-path OCT integrated microsurgical tool

    Science.gov (United States)

    Liu, Xuan; Meisne, Eric; Han, Jae-Ho; Zhang, Kang; Gehlbach, Peter; Taylor, Russell; Kang, Jin U.

    2010-02-01

    Contemporary retinal microsurgery is performed by skilled surgeons through operating microscopes, utilizing free hand techniques and manually operated micro-instruments. One technically challenging procedure is the incising and peeling of the internal limiting membrane (ILM) while minimizing damage to the underlying retina. One strategy for minimizing damage is to improve visualization of the ILM layer. Here we present a preliminary evaluation of a prototype tool that integrates an ultra high resolution Fourier domain common path Optical Coherence Tomography (OCT) with an intelligent microsurgical instrument. The tool provides OCT guided visualization of the ILM layer at the point of tissue contact by the surgical tool. We have evaluated the imaging properties of the common path OCT system. The common path OCT system used in this study has a maximum imaging depth of 1.3mm and a sensitivity of 91dB. We have achieved an experimental axial resolution of 3μm in air and this appears to be sufficient to both identify the ILM and to perform surgical maneuvers. We scanned the single mode fiber probe using an intelligent microsurgical instrument to form B-Mode images. We imaged a porcine eye with both anterior eye segment and the vitreous removed. The image obtained show distinct functional layers of retina.

  7. Defects in the Outer Limiting Membrane Are Associated with Rosette Development in the Nrl−/− Retina

    Science.gov (United States)

    Stuck, Michael W.; Conley, Shannon M.; Naash, Muna I.

    2012-01-01

    The neural retinal leucine zipper (Nrl) knockout mouse is a widely used model to study cone photoreceptor development, physiology, and molecular biology in the absence of rods. In the Nrl−/− retina, rods are converted into functional cone-like cells. The Nrl−/− retina is characterized by large undulations of the outer nuclear layer (ONL) commonly known as rosettes. Here we explore the mechanism of rosette development in the Nrl−/− retina. We report that rosettes first appear at postnatal day (P)8, and that the structure of nascent rosettes is morphologically distinct from what is seen in the adult retina. The lumen of these nascent rosettes contains a population of aberrant cells protruding into the subretinal space that induce infolding of the ONL. Morphologically adult rosettes do not contain any cell bodies and are first detected at P15. The cells found in nascent rosettes are photoreceptors in origin but lack inner and outer segments. We show that the adherens junctions between photoreceptors and Müller glia which comprise the retinal outer limiting membrane (OLM) are not uniformly formed in the Nrl−/− retina and thus allow protrusion of a population of developing photoreceptors into the subretinal space where their maturation becomes delayed. These data suggest that the rosettes of the Nrl−/− retina arise due to defects in the OLM and delayed maturation of a subset of photoreceptors, and that rods may play an important role in the proper formation of the OLM. PMID:22427845

  8. Clinical efficacy and safety of limited internal fixation combined with external fixation for Pilon fracture: A systematic review and meta-analysis.

    Science.gov (United States)

    Zhang, Shao-Bo; Zhang, Yi-Bao; Wang, Sheng-Hong; Zhang, Hua; Liu, Peng; Zhang, Wei; Ma, Jing-Lin; Wang, Jing

    2017-04-01

    To compare the clinical efficacy and complications of limited internal fixation combined with external fixation (LIFEF) and open reduction and internal fixation (ORIF) in the treatment of Pilon fracture. We searched databases including Pubmed, Embase, Web of science, Cochrane Library and China Biology Medicine disc for the studies comparing clinical efficacy and complications of LIFEF and ORIF in the treatment of Pilon fracture. The clinical efficacy was evaluated by the rate of nonunion, malunion/delayed union and the excellent/good rate assessed by Mazur ankle score. The complications including infections and arthritis symptoms after surgery were also investigated. Nine trials including 498 pilon fractures of 494 patients were identified. The meta-analysis found no significant differences in nonunion rate (RR = 1.60, 95% CI: 0.66 to 3.86, p = 0.30), and the excellent/good rate (RR = 0.95, 95% CI: 0.86 to 1.04, p = 0.28) between LIFEF group and ORIF group. For assessment of infections, there were significant differences in the rate of deep infection (RR = 2.18, 95% CI: 1.34 to 3.55, p = 0.002), and the rate of arthritis (RR = 1.26, 95% CI: 1.03 to 1.53, p = 0.02) between LIFEF group and ORIF group. LIFEF has similar effect as ORIF in the treatment of pilon fractures, however, LIFEF group has significantly higher risk of complications than ORIF group does. So LIFEF is not recommended in the treatment of pilon fracture. Copyright © 2017 Daping Hospital and the Research Institute of Surgery of the Third Military Medical University. Production and hosting by Elsevier B.V. All rights reserved.

  9. Expression of human CEACAM1 in transgenic mice limits the Opa-specific immune response against meningococcal outer membrane vesicles.

    NARCIS (Netherlands)

    Zariri, A.; Dijken, H. van; Hamstra, H.J.; Flier, M. van der; Vidarsson, G.; Putten, J.P. van; Boog, C.J.; Dobbelsteen, G. van den; Ley, P. van der

    2013-01-01

    Outer membrane vesicles (OMVs) have been extensively investigated as meningococcal vaccine candidates. Among their major components are the opacity (Opa) proteins, a family of surface-exposed outer membrane proteins important for bacterial adherence and entry into host cells. Many Opa-dependent

  10. Effect of Mass-Transport Limitations on the Performance of a Packed Bed Membrane Reactor for Partial Oxidations. Transport from the Membrane to the Packed Bed

    NARCIS (Netherlands)

    Sint Annaland, van M.; Kürten, U.; Kuipers, J.A.M.

    2007-01-01

    With a packed bed membrane reactor, the product yield can be significantly enhanced for partial oxidation systems, via distributive addition of oxygen to the reaction mixture along the axial coordinate of the reactor, provided that the reaction order in oxygen of the formation rate of the target pro

  11. Pars plana vitrectomy combined with internal limiting membrane peeling for recurrent macular edema due to branch retinal vein occlusion after antivascular endothelial growth factor treatments

    Directory of Open Access Journals (Sweden)

    Shirakata Y

    2016-02-01

    Full Text Available Yukari Shirakata,1 Kouki Fukuda,1 Tomoyoshi Fujita,1 Yuki Nakano,1 Hiroyuki Nomoto,2 Hidetaka Yamaji,3 Fumio Shiraga,4 Akitaka Tsujikawa1 1Department of Ophthalmology, Faculty of Medicine, Kagawa University, Miki-cho, 2Nomoto Eye Clinic, Himeji, 3Department of Ophthalmology, Shirai Eye Hospital, Mitoyo, 4Department of Ophthalmology, Okayama University, Okayama, Japan Purpose: To evaluate the anatomic and functional outcomes of pars plana vitrectomy combined with internal limiting membrane peeling for recurrent macular edema (ME due to branch retinal vein occlusion (BRVO after intravitreal injections of antivascular endothelial growth factor (anti-VEGF agents. Methods: Twenty-four eyes of 24 patients with treatment-naive ME from BRVO were treated with intravitreal injections of anti-VEGF agents. Recurred ME was treated with pars plana vitrectomy combined with internal limiting membrane peeling. Results: After the surgery, ME was significantly reduced at 1 month (P=0.031 and the reduction increased with time (P=0.007 at the final visit. With the reduction in ME, treated eyes showed a slow improvement in visual acuity (VA. At the final visit, improvement in VA was statistically significant compared with baseline (P=0.048. The initial presence of cystoid spaces, serous retinal detachment, or subretinal hemorrhage under the fovea, as well as retinal perfusion status, showed no association with VA improvement. However, the presence of epiretinal membrane showed a significant association with the visual recovery. Although eyes without epiretinal membrane showed visual improvement (-0.10±0.32 in logarithm of the minimum angle of resolution [logMAR], eyes with epiretinal membrane showed greater visual improvement (-0.38±0.12 in logMAR, P=0.012. Conclusion: For recurrent ME due to BRVO after anti-VEGF treatment, particularly when accompanied by epiretinal membrane, pars plana vitrectomy combined with internal limiting membrane peeling might be a

  12. ExternE National Implementation Finland

    Energy Technology Data Exchange (ETDEWEB)

    Pingoud, K.; Maelkki, H.; Wihersaari, M.; Pirilae, P. [VTT Energy, Espoo (Finland); Hongisto, M. [Imatran Voima Oy, Vantaa (Finland); Siitonen, S. [Ekono Energy Ltd, Espoo (Finland); Johansson, M. [Finnish Environment Institute, Helsinki (Finland)

    1999-07-01

    ExternE National Implementation is a continuation of the ExternE Project, funded in part by the European Commission's Joule III Programme. This study is the result of the ExternE National Implementation Project for Finland. Three fuel cycles were selected for the Finnish study: coal, peat and wood-derived biomass, which together are responsible for about 40% of total electricity generation in Finland and about 75% of the non-nuclear fuel based generation. The estimated external costs or damages were dominated by the global warming (GW) impacts in the coal and peat fuel cycles, but knowledge of the true GW impacts is still uncertain. From among other impacts that were valued in monetary terms the human health damages due to airborne emissions dominated in all the three fuel cycles. Monetary valuation for ecosystem impacts is not possible using the ExternE methodology at present. The Meri-Pori power station representing the coal fuel cycle is one of the world's cleanest and most efficient coal-fired power plants with a condensing turbine. The coal is imported mainly from Poland. The estimated health damages were about 4 mECU/kWh, crop damages an order of magnitude lower and damages caused to building materials two orders of magnitude lower. The power stations of the peat and biomass fuel cycles are of CHP type, generating electricity and heat for the district heating systems of two cities. Their fuels are of domestic origin. The estimated health damages allocated to electricity generation were about 5 and 6 mECU/kWh, respectively. The estimates were case-specific and thus an generalisation of the results to the whole electricity generation in Finland is unrealistic. Despite the uncertainties and limitations of the methodology, it is a promising tool in the comparison of similar kinds of fuel cycles, new power plants and pollution abatement technologies and different plant locations with each other. (orig.)

  13. Outcomes of microincision vitrectomy surgery with internal limiting membrane peeling for macular edema secondary to branch retinal vein occlusion

    Directory of Open Access Journals (Sweden)

    Sato S

    2015-03-01

    Full Text Available Shimpei Sato,1 Maiko Inoue,2 Shin Yamane,2 Akira Arakawa,2 Mikiro Mori,1 Kazuaki Kadonosono2 1Department of Opthalmology, Toranomon Hospital, Tokyo, Japan; 2Department of Ophthalmology, Yokohama City University Medical Center, Yokohama, Japan Purpose: To evaluate the anatomic and functional effect of microincision vitrectomy surgery (MIVS with internal limiting membrane (ILM peeling for macular edema secondary to branch retinal vein occlusion (BRVO.Methods: The medical records of 101 eyes of 101 patients who had undergone MIVS with ILM peeling for macular edema secondary to BRVO were studied. Patients were classified into ischemic and non-ischemic BRVO based on angiograph. The best-corrected visual acuity (BCVA and central foveal thickness (CFT, determined by spectral domain optical coherence tomography, were evaluated at baseline and at 1, 3, 6, and 12 months postoperatively.Results: Preoperative mean logarithm of the minimum angle of resolution (logMAR BCVA ± standard deviation (SD was 0.52±0.43 and mean CFT ± SD was 489.4±224.9 µm. Postoperative mean BCVA ± SD values were 0.41±0.35, 0.35±0.41, 0.29±0.36, and 0.25±0.41, and mean CFT values were 370.1±148.9, 327.5±157.5, 310.9±154.9, and 274.4±135.3 µm at 1, 3, 6, 12 months, respectively. The mean BCVA was significantly improved at 3, 6, and 12 months postoperatively (all P<0.05, and the mean CFT was significantly decreased at all postoperative follow-up time points (all P<0.05. At the 12-month postoperative evaluation, BCVA had improved by 0.2 logMAR units in 50 eyes (60.0% with ischemic BRVO and in nine eyes (50.0% with non-ischemic BRVO. Six eyes (6.0% experienced recurrence or persistence of macular edema at 12 months postoperatively.Conclusion: MIVS with ILM peeling for macular edema secondary to BRVO is effective in improving visual acuity and foveal morphology with low recurrence of macular edema. Keywords: MIVS, ILM, BRVO, central foveal thickness, CFT

  14. High-flux ionic diodes, ionic transistors and ionic amplifiers based on external ion concentration polarization by an ion exchange membrane: a new scalable ionic circuit platform.

    Science.gov (United States)

    Sun, Gongchen; Senapati, Satyajyoti; Chang, Hsueh-Chia

    2016-04-07

    A microfluidic ion exchange membrane hybrid chip is fabricated using polymer-based, lithography-free methods to achieve ionic diode, transistor and amplifier functionalities with the same four-terminal design. The high ionic flux (>100 μA) feature of the chip can enable a scalable integrated ionic circuit platform for micro-total-analytical systems.

  15. COMPARATIVE EVALUATION OF SEQUENTIAL INTRAOPERATIVE USE OF WHOLE BLOOD FOLLOWED BY BRILLIANT BLUE VERSUS CONVENTIONAL BRILLIANT BLUE STAINING OF INTERNAL LIMITING MEMBRANE IN MACULAR HOLE SURGERY.

    Science.gov (United States)

    Ghosh, Basudeb; Arora, Supriya; Goel, Neha; Seth, Anisha; Pyare, Richa; Sridharan, Preethi; Thakar, Meenakshi

    2016-08-01

    To compare the structural and functional outcome of use of autologous heparinized whole blood before staining internal limiting membrane with brilliant blue (BB) versus conventional BB-assisted macular hole surgery. Sixty eyes of 60 patients were randomly divided equally in Group A (BB staining using whole blood) and Group B (conventional BB staining). Clinical assessment and spectral domain optical coherence tomography was done at baseline and 3 weeks, 6 weeks, 16 weeks, and 6 months postoperatively. Group A eyes had a significantly higher best-corrected visual acuity as compared with Group B postoperatively (P blood before staining internal limiting membrane with BB causes earlier and better visual rehabilitation postoperatively, which could be attributed to earlier photoreceptor regeneration as evidenced by inner segment/outer segment junction continuity and increase in outer foveal thickness.

  16. PVC膜离子选择电极检测下限的优化%Improvement of Lower Detection Limit of Ion-Selective Electrodes Based on PVC Membrane

    Institute of Scientific and Technical Information of China (English)

    黄美荣; 丁永波; 李新贵

    2012-01-01

    Ion-selective electrodes (ISEs) based on polymeric membranes are characterized by small size, portability, low-energy consumption, and low cost, which are attractive features concerning practical applications. However, the lower detection limit is biased by the ion flux through PVC membrane, which limits the further development of ion-selective electrode. Therefore, the principles and attractive strategies to suppress such an ion flux to improve the lower detection limit of PVC membrane-based ion-selective electrodes are elaborated in this article. According to large amounts of data collected, the improvement of the detection limit via optimization of sensing membrane composition, electrode assembly and conditioning, electrode rotation, as well as current- polarized treatment, is quantitatively discussed. Furthermore, the modification regulations for expanding the lower detection limit are systematically summarized. The significant superiority and problems are analyzed. It is pointed out that we have to break the conventional PVC composition formulation via reducing the dosages of plasticizer and ion exchanger in order to largely depress the transmembrane ion flux. External-current application to the electrode is also an effective approach, among which, the best improvement for the lower detection limit can reach up to 5 orders of magnitude. This review reveals the future direction for developing the PVC membrane-based ion-selective electrodes with high performance.%价格低廉、携带方便、适用浓度宽、操作简单快捷、能耗低的离子选择电极在医院、分析实验室、野外等领域得到了越来越广泛的应用。尽管如此,由于PVC膜中存在的离子流严重破坏了更低检测下限的获取,限制了离子选择电极的进一步发展。因此,本文从减小甚至消除PVC膜中存在的离子流角度出发,系统论述了优化PVC膜离子选择电极检测下限的原理和优良策略,根据收集归纳的大量数

  17. Evaluation of Macular Retinal Ganglion Cell-Inner Plexiform Layer Thickness after Vitrectomy with Internal Limiting Membrane Peeling for Idiopathic Macular Holes

    Directory of Open Access Journals (Sweden)

    Alfonso L. Sabater

    2014-01-01

    Full Text Available Purpose. To evaluate macular retinal ganglion cell-inner plexiform layer (GCIPL thickness changes after Brilliant Blue G-assisted internal limiting membrane peeling for idiopathic macular hole repair using a high-resolution spectral-domain optical coherence tomography (SD-OCT. Methods. 32 eyes from 32 patients with idiopathic macular holes who underwent vitrectomy with internal limiting membrane peeling between January 2011 and July 2012 were retrospectively analyzed. GCIPL thickness was measured before surgery, and at one month and at six months after surgery. Values obtained from automated and semimanual SD-OCT segmentation analysis were compared (Cirrus HD-OCT, Carl Zeiss Meditec, Dublin, CA. Results. No significant differences were found between average GCIPL thickness values between preoperative and postoperative analysis. However, statistical significant differences were found in GCIPL thickness at the temporal macular quadrants at six months after surgery. Quality measurement analysis performed by automated segmentation revealed a significant number of segmentation errors. Semimanual segmentation slightly improved the quality of the results. Conclusion. SD-OCT analysis of GCIPL thickness found a significant reduction at the temporal macular quadrants at 6 months after Brilliant Blue G-assisted internal limiting membrane peeling for idiopathic macular hole.

  18. Evaluation of Macular Retinal Ganglion Cell-Inner Plexiform Layer Thickness after Vitrectomy with Internal Limiting Membrane Peeling for Idiopathic Macular Holes

    Science.gov (United States)

    Velázquez-Villoria, Álvaro; Zapata, Miguel A.; Figueroa, Marta S.; Suárez-Leoz, Marta; Arrevola, Luis; Teijeiro, María-Ángeles; García-Layana, Alfredo

    2014-01-01

    Purpose. To evaluate macular retinal ganglion cell-inner plexiform layer (GCIPL) thickness changes after Brilliant Blue G-assisted internal limiting membrane peeling for idiopathic macular hole repair using a high-resolution spectral-domain optical coherence tomography (SD-OCT). Methods. 32 eyes from 32 patients with idiopathic macular holes who underwent vitrectomy with internal limiting membrane peeling between January 2011 and July 2012 were retrospectively analyzed. GCIPL thickness was measured before surgery, and at one month and at six months after surgery. Values obtained from automated and semimanual SD-OCT segmentation analysis were compared (Cirrus HD-OCT, Carl Zeiss Meditec, Dublin, CA). Results. No significant differences were found between average GCIPL thickness values between preoperative and postoperative analysis. However, statistical significant differences were found in GCIPL thickness at the temporal macular quadrants at six months after surgery. Quality measurement analysis performed by automated segmentation revealed a significant number of segmentation errors. Semimanual segmentation slightly improved the quality of the results. Conclusion. SD-OCT analysis of GCIPL thickness found a significant reduction at the temporal macular quadrants at 6 months after Brilliant Blue G-assisted internal limiting membrane peeling for idiopathic macular hole. PMID:25110679

  19. Value of internal limiting membrane peeling in surgery for idiopathic macular hole and the correlation between function and retinal morphology.

    Science.gov (United States)

    Christensen, Ulrik Correll

    2009-12-01

    Idiopathic macular hole is characterized by a full thickness anatomic defect in the foveal retina leading to loss of central vision, metamorphopsia and a central scotoma. Classic macular hole surgery consists of vitrectomy, posterior vitreous cortex separation and intraocular gas tamponade, but during the past decade focus has especially been on internal limiting membrane (ILM) peeling as adjuvant therapy for increasing closure rates. With increasing use of ILM peeling and indocyanine green (ICG) staining, which is used for specific visualization of the ILM, concerns about the safety of the procedure have arisen. At present, it is not known whether ICG-assisted ILM peeling potentially reduces the functional outcome after macular hole surgery. The purpose of the present PhD thesis was to examine whether ICG-assisted ILM peeling offers surgical and functional benefit in macular hole surgery. We conducted a randomized clinical trial including 78 pseudophakic patients with idiopathic macular hole stages 2 and 3. Patients were randomly assigned to macular hole surgery consisting of (i) vitrectomy alone without instrumental retinal surface contact (non-peeling), (ii) vitrectomy plus 0.05% isotonic ICG-assisted ILM peeling or (iii) vitrectomy plus 0.15% trypan blue (TB)-assisted ILM peeling. Morphologic and functional outcomes were assessed 3, 6 and 12 months after surgery. The results show that surgery with ILM peeling, for both stages 2 and 3 macular holes, is associated with a significantly higher closure rate than surgery without ILM peeling (95% versus 45%). The overall functional results confirm that surgery for macular hole generally leads to favourable visual results, with two-thirds of eyes regaining reading vision (>or=20/40). Macular hole surgery can be considered a safe procedure with a low incidence of sight-threatening adverse events; the retinal detachment rate was 2.2%. Visual outcomes in eyes with primary hole closure were not significantly different

  20. 建筑外部环境空间以小见大的手法探析%Study on Creation of Infinite Space in Limited Place for External Architectural Environmental Space

    Institute of Scientific and Technical Information of China (English)

    王莉珊; 张鸣

    2012-01-01

    解析了建筑外环境空间大小的含义,以及“以小见大”空间设计手法.从静态观察和动态体验过程以及建筑外部环境场的尺度设计3个角度,探讨了建筑外部环境空间如何由“小”来得到美而丰富的空间体验的方法与途径.旨在尊重自然、顺应自然、尊重历史的前提下,精心设计建筑环境景观空间.%Connotations of " limited" and " infinite" external architectural environmental space were explored, and spatial design techniques of creating infinite space in limited place were introduced. Approaches of obtaining beautiful and colorful spatial experience from the limited external architectural environmental space were explored from three perspectives: stationary observation, dynamic experience, and scale design of external architectural environment field. The study aimed at designing architectural environment space delicately on the basis of respecting the nature and history.

  1. Limitations to the use of extracellular acidification for the assessment of plasma membrane H[sup +]-ATPase activity and ethanol tolerance in yeasts

    Energy Technology Data Exchange (ETDEWEB)

    Rosa, M.F. (Instituto Nacional de Engenharia e Tecnologia Industrial, Lisbon (Portugal). Dept. de Energias Renovaveis); Sa-Correia, Isabel (Instituto Superior Tecnico, Lisbon (Portugal). Lab. de Engenharia Bioquimica)

    1994-09-01

    When yeast cells are grown in low but inhibitory concentrations of ethanol, the proton-pumping activity is stimulated but no significant increase of the plasma membrane permeability is observed. These cell responses can only be appraised through the effect of ethanol on the acidification curves when cells have been grown in the presence of ethanol. In addition, and since the in vivo activation of plasma membrane H[sup +] -ATPase by ethanol is rapidly reversed in vivo after its removal, yeast cells to be used to obtain the acidification curves should be maintained in permanent contact with ethanol. However, when the differently ethanol-tolerant strains Saccharomyces cerevisiae IGC 3507 III and Kluyveromyces marxianus IGC 2671 are grown in the presence of concentrations close to the maximal for growth, the development of responses to counteract the dissipation of the proton motive force induced by ethanol is hindered. Therefore, for these high concentrations, the ethanol-induced increase of the final external pH attained after glucose addition in aqueous suspensions of deenergized cells, grown in the absence of ethanol, can be used as a rapid criterion for the evaluation of ethanol tolerance. (author)

  2. Limited cross-reactivity among domains of the Plasmodium falciparum clone 3D7 erythrocyte membrane protein 1 family

    DEFF Research Database (Denmark)

    Joergensen, Louise; Turner, Louise; Magistrado, Pamela

    2006-01-01

    The var gene-encoded Plasmodium falciparum erythrocyte membrane protein 1 (PfEMP1) family is responsible for antigenic variation and sequestration of infected erythrocytes during malaria. We have previously grouped the 60 PfEMP1 variants of P. falciparum clone 3D7 into groups A and B/A (category A...... from clone 3D7 by using a competition enzyme-linked immunosorbent assay and a pool of plasma from 63 malaria-exposed Tanzanian individuals. We conclude that naturally acquired antibodies are largely directed toward epitopes varying between different domains with a few, mainly category A, domains...

  3. Experimental investigation on a polymer electrolyte membrane fuel cell (PEMFC) parallel flow field design with external two-valve regulation on cathode channels

    Science.gov (United States)

    Tong, Shijie; Bachman, John C.; Santamaria, Anthony; Park, Jae Wan

    2013-11-01

    Parallel/interdigitated/serpentine flow field PEM fuel cells have similar performance under low overvoltage operation. At higher overvoltage, interdigitated/serpentine flow field performance may exceed parallel flow field designs due to better water removal and more uniform reactant distribution by convective reactant flow in the GDL under land area, i.e. cross flow. However, serpentine flow field design suffers from high pumping losses and the risk of local flooding at channel U-bends. Additionally, interdigitated flow field designs may have higher local flooding risk in the inlet channels and relatively large pumping requirement at low current densities. In this study, a novel parallel flow field design with external two-valve regulation on the cathode was presented. Two valves introduced continuous pressure differences to two separate manifolds in the cathode that induce cross flow across the land areas. Moreover, both valves remained partially open to maintain a good water removal from flow channels. Comparative test results showed the proposed design surpasses performance of both parallel and interdigitated flow field design at operation current density of 0.7 A cm-2 or higher. The performance enhancement is 10.9% at peak power density point (0.387 W cm-2 @ 0.99 A cm-2) compared to parallel flow field taking into account pumping losses.

  4. Dynamic recruitment of the curvature-sensitive protein ArhGAP44 to nanoscale membrane deformations limits exploratory filopodia initiation in neurons

    Science.gov (United States)

    Galic, Milos; Tsai, Feng-Chiao; Collins, Sean R; Matis, Maja; Bandara, Samuel; Meyer, Tobias

    2014-01-01

    In the vertebrate central nervous system, exploratory filopodia transiently form on dendritic branches to sample the neuronal environment and initiate new trans-neuronal contacts. While much is known about the molecules that control filopodia extension and subsequent maturation into functional synapses, the mechanisms that regulate initiation of these dynamic, actin-rich structures have remained elusive. Here, we find that filopodia initiation is suppressed by recruitment of ArhGAP44 to actin-patches that seed filopodia. Recruitment is mediated by binding of a membrane curvature-sensing ArhGAP44 N-BAR domain to plasma membrane sections that were deformed inward by acto-myosin mediated contractile forces. A GAP domain in ArhGAP44 triggers local Rac-GTP hydrolysis, thus reducing actin polymerization required for filopodia formation. Additionally, ArhGAP44 expression increases during neuronal development, concurrent with a decrease in the rate of filopodia formation. Together, our data reveals a local auto-regulatory mechanism that limits initiation of filopodia via protein recruitment to nanoscale membrane deformations. DOI: http://dx.doi.org/10.7554/eLife.03116.001 PMID:25498153

  5. Poly-thiosemicarbazide membrane for gold recovery

    KAUST Repository

    Villalobos, Luis Francisco

    2014-11-01

    A novel polymeric membrane adsorber with a high density of adsorption sites that can selectively capture Au(III) ions, is proposed as an efficient alternative to recover gold from dilute solutions. Poly-thiosemicarbazide (PTSC), a polymer that contains one chelate site per monomeric unit, was used to fabricate the membranes. This polymer can be easily processed into membranes by a phase inversion technique, resulting in an open and interconnected porous structure suitable for high flux liquid phase applications. This method overcomes the usual low capacities of membrane adsorbents by selecting a starting material that contains the adsorption sites within it, therefore avoiding the necessity to add an external agent into the membrane matrix. The resulting mechanically stable PTSC membranes can operate in a pressure driven permeation process, which eliminates the diffusion limitations commonly present in packed column adsorption processes. This process can selectively recover 97% of the gold present in a solution containing a 9-fold higher copper concentration, while operating at a flux as high as 1868 L/m2 h. The maximum gold uptake measured without sacrificing the mechanical stability of the membrane was 5.4 mmol Au/g. Furthermore the gold can be easily eluted from the membrane with a 0.1 M thiourea solution and the membrane can be reused for at least three cycles without any decrease in its performance. Finally, the ability of this membrane for recovering metals from real-life samples, like seawater and tap water, was tested with promising results.

  6. Limited internal fixation combined external fixation in the treatment of distal radius comminuted fractures%有限内固定加外固定支架治疗桡骨远端粉碎性骨折

    Institute of Scientific and Technical Information of China (English)

    向乾彬; 范海泉; 黄海讯; 俞阳; 江洋; 刘江川; 陈铭

    2012-01-01

    目的 探讨有限内固定加外固定支架治疗桡骨远端粉碎性骨折的临床疗效.方法 采用有限内固定加外固定支架治疗桡骨远端粉碎性骨折45例.结果 42例患者获得随访,时间3~36个月.按Lidstrom评分系统行影像学评价:优30例,良7例,中5例,优良率为88.09%;依据Dienst标准评价腕关节功能:优30例,良8 例,中4 例,优良率为90.47%.无严重并发症发生.结论 有限内固定结合外固定支架治疗桡骨远端粉碎性骨折,复位满意,操作简单,固定牢固,疗效满意.%Objective To study the effect of limited internal fixation and external fixation for the treatment of comminuted fracture of distal radius. Methods Limited internal fixation combined with external fixation were used in the treatment of 45 cases of comminuted fracture of distal radius. Results 42 cases were followed up for 3 ~ 36 months. With Lidstrom scoring system image evaluation, excellent 30 cases,7 good,5 fair,and the excellent and good rate was 88. 09% ; According to Dienst functional evaluation standard, the wrist joint function evaluation was excellent in 30 cases, good in 8, and fair in 4 cases, and the excellent and good rate was 90. 47%. No serious complications were found. Conclusions Limited internal fixation combined external fixation for distal radius comminuted fractures provide good reduction and satisfactory effect.

  7. Generation of more than 300 mW diffraction-limited light at 405 nm by second-harmonic generation of a tapered diode laser with external cavity feedback

    DEFF Research Database (Denmark)

    Jensen, Ole Bjarlin; Holm, J.; Sumpf, B.;

    2007-01-01

    We have constructed a blue laser source consisting of a single-frequency tapered diode laser with external cavity feedback that is frequency doubled by a quasi-phase matched KTP (PPKTP) in a bowtie ring cavity and extract more than 360 mW of power at 405 nm. The conversion efficiency from fundame...... fundamental laser power to second harmonic power is 35 %, while it is 64 % from coupled fundamental power to extracted blue light. Thermal effects and gray tracking set an upper limit on the amount of generated blue light....

  8. Integrating membrane filtration into bioelectrochemical systems as next generation energy-efficient wastewater treatment technologies for water reclamation: A review.

    Science.gov (United States)

    Yuan, Heyang; He, Zhen

    2015-11-01

    Bioelectrochemical systems (BES) represent an energy-efficient approach for wastewater treatment, but the effluent still requires further treatment for direct discharge or reuse. Integrating membrane filtration in BES can achieve high-quality effluents with additional benefits. Three types of filtration membranes, dynamic membrane, ultrafiltration membrane and forward osmosis membrane that are grouped based on pore size, have been studied for integration in BES. The integration can be accomplished either in an internal or an external configuration. In an internal configuration, membranes can act as a separator between the electrodes, or be immersed in the anode/cathode chamber as a filtration component. The external configuration allows BES and membrane module to be operated independently. Given much progress and interest in the integration of membrane filtration into BES, this paper has reviewed the past studies, described various integration methods, discussed the advantages and limitations of each integration, and presented challenges for future development.

  9. Performance of Multiple Risk Assessment Tools to Predict Mortality for Adult Respiratory Distress Syndrome with Extracorporeal Membrane Oxygenation Therapy: An External Validation Study Based on Chinese Single-center Data

    Institute of Scientific and Technical Information of China (English)

    Lei Huang; Tong Li; Lei Xu; Xiao-Min Hu; Da-Wei Duan; Zhi-Bo Li; Xin-Jing Gao

    2016-01-01

    Background:There has been no external validation of survival prediction models for severe adult respiratory distress syndrome (ARDS) with extracorporeal membrane oxygenation (ECMO) therapy in China.The aim of study was to compare the performance of multiple models recently developed for patients with ARDS undergoing ECMO based on Chinese single-center data.Methods:A retrospective case study was performed,including twenty-three severe ARDS patients who received ECMO from January 2009 to July 2015.The PRESERVE (Predicting death for severe ARDS on VV-ECMO),ECMOnet,Respiratory Extracorporeal Membrane Oxygenation Survival Prediction (RESP) score,a center-specific model developed for inter-hospital transfers receiving ECMO,and the classical risk-prediction scores of Acute Physiology and Chronic Health Evaluation (APACHE) Ⅱ and Sequential Organ Failure Assessment (SOFA) were calculated.In-hospital and six-month mortality were regarded as the endpoints and model performance was evaluated by comparing the area under the receiver operating characteristic curve (AUC).Results:The RESP and APACHE Ⅱ scores showed excellent discriminate performance in predicting survival with AUC of 0.835 (95% confidence interval [CI],0.659-1.010,P =0.007) and 0.762 (95% CI,0.558-0.965,P =0.035),respectively.The optimal cutoff values were risk class 3.5 for RESP and 35.5 for APACHE Ⅱ score,and both showed 70.0% sensitivity and 84.6% specificity.The excellent performance of these models was also evident for the pneumonia etiological subgroup,for which the SOFA score was also shown to be predictive,with an AUC of 0.790 (95% CI,0.571-1.009,P =0.038).However,the ECMOnet and the score developed for externally retrieved ECMO patients failed to demonstrate significant discriminate power for the overall cohort.The PRESERVE model was unable to be evaluated fully since only one patient died six months postdischarge.Conclusions:The RESP,APCHAE Ⅱ,and SOFA scorings systems show good

  10. Microfiltration: Effect of retentate protein concentration on limiting flux and serum protein removal with 4-mm-channel ceramic microfiltration membranes.

    Science.gov (United States)

    Hurt, E E; Adams, M C; Barbano, D M

    2015-04-01

    The objective of our study was to determine if the limiting flux and serum protein (SP) removal were different at 8, 9, or 10% true protein (TP) in the microfiltration (MF) retentate recirculation loop using 0.1-µm ceramic graded permeability membranes with 4-mm-channel diameters operated at 50 °C using a diluted milk protein concentrate with 85% protein on a total solids basis (MPC85) as the MF feed. The limiting flux for the MF of diluted MPC85 was determined at 3 TP concentrations in the recirculation loop (8, 9, and 10%). The experiment was replicated 3 times for a total of 9 runs. On the morning of each run, MPC85 was diluted with reverse osmosis water to an MF feed TP concentration of 5.4%. In all runs, the starting flux was 55 kg/m(2) per hour, the flux was increased in steps until the limiting flux was reached. The minimum flux increase was 10 kg/m(2) per hour. The limiting flux decreased as TP concentration in the recirculation loop increased. The limiting flux was 154 ± 0.3, 133 ± 0.7, and 117 ± 3.3 kg/m(2) per hour at recirculation loop TP concentrations of 8.2 ± 0.07, 9.2 ± 0.04, and 10.2 ± 0.09%, respectively. No effect of recirculation loop TP concentration on the SP removal factor was detected. However, the SP removal factor decreased from 0.80 ± 0.02 to 0.75 ± 0.02 as flux was increased from the starting flux of 55 kg/m(2) per hour to the limiting flux, with a similar decrease seen at all recirculation loop TP concentrations.

  11. An allosteric rheostat in HIV-1 gp120 reduces CCR5 stoichiometry required for membrane fusion and overcomes diverse entry limitations.

    Science.gov (United States)

    Platt, Emily J; Durnin, James P; Shinde, Ujwal; Kabat, David

    2007-11-16

    ensemble of compositions, and that HIV-1 adapts to entry limitations by gp120 mutations that reduce its allosteric hold on gp41. These results provide an important foundation for understanding the mechanisms that control membrane fusion and HIV-1's facile adaptability.

  12. Ion permeabilities in mouse sperm reveal an external trigger for SLO3-dependent hyperpolarization.

    Directory of Open Access Journals (Sweden)

    Julio C Chávez

    Full Text Available Unlike most cells of the body which function in an ionic environment controlled within narrow limits, spermatozoa must function in a less controlled external environment. In order to better understand how sperm control their membrane potential in different ionic conditions, we measured mouse sperm membrane potentials under a variety of conditions and at different external K(+ concentrations, both before and after capacitation. Experiments were undertaken using both wild-type, and mutant mouse sperm from the knock-out strain of the sperm-specific, pH-sensitive, SLO3 K(+ channel. Membrane voltage data were fit to the Goldman-Hodgkin-Katz equation. Our study revealed a significant membrane permeability to both K(+ and Cl(- before capacitation, as well as Na(+. The permeability to both K(+ and Cl(- has the effect of preventing large changes in membrane potential when the extracellular concentration of either ion is changed. Such a mechanism may protect against undesired shifts in membrane potential in changing ionic environments. We found that a significant portion of resting membrane potassium permeability in wild-type sperm was contributed by SLO3 K(+ channels. We also found that further activation of SLO3 channels was the essential mechanism producing membrane hyperpolarization under two separate conditions, 1 elevation of external pH prior to capacitation and 2 capacitating conditions. Both conditions produced a significant membrane hyperpolarization in wild-type which was absent in SLO3 mutant sperm. Hyperpolarization in both conditions may result from activation of SLO3 channels by raising intracellular pH; however, demonstrating that SLO3-dependent hyperpolarization is achieved by an alkaline environment alone shows that SLO3 channel activation might occur independently of other events associated with capacitation. For example sperm may undergo stages of membrane hyperpolarization when reaching alkaline regions of the female genital tract

  13. Membrane-less microfiltration using inertial microfluidics.

    Science.gov (United States)

    Warkiani, Majid Ebrahimi; Tay, Andy Kah Ping; Guan, Guofeng; Han, Jongyoon

    2015-07-08

    Microfiltration is a ubiquitous and often crucial part of many industrial processes, including biopharmaceutical manufacturing. Yet, all existing filtration systems suffer from the issue of membrane clogging, which fundamentally limits the efficiency and reliability of the filtration process. Herein, we report the development of a membrane-less microfiltration system by massively parallelizing inertial microfluidics to achieve a macroscopic volume processing rates (~ 500 mL/min). We demonstrated the systems engineered for CHO (10-20 μm) and yeast (3-5 μm) cells filtration, which are two main cell types used for large-scale bioreactors. Our proposed system can replace existing filtration membrane and provide passive (no external force fields), continuous filtration, thus eliminating the need for membrane replacement. This platform has the desirable combinations of high throughput, low-cost, and scalability, making it compatible for a myriad of microfiltration applications and industrial purposes.

  14. Flow Curve Determination at Large Plastic Strain Levels: Limitations of the Membrane Theory in the Analysis of the Hydraulic Bulge Test

    Science.gov (United States)

    Lemoine, X.; Iancu, A.; Ferron, G.

    2011-05-01

    Nowadays, an accurate determination of the true stress-strain curve is a key-element for all finite element (FE) forming predictions. Since the introduction of Advanced High Strength Steels (AHSS) for the automotive market, the standard uniaxial tension test suffers the drawback of relatively low uniform elongations. The extrapolation of the uniaxial stress-strain curve up to large strains is not without consequence in forming predictions—especially formability and springback. One of the means to solve this problem is to use experimental tests where large plastic strain levels can be reached. The hydraulic bulge test is one of these tests. The effective plastic strain levels reached in the bulge test are of about 0.7. From an experimental standpoint, the biaxial flow stress is estimated using measurement of fluid pressure, and calculation of thickness and curvature at the pole, via appropriate measurements and assumptions. The biaxial stress at the pole is determined using the membrane equilibrium equation. The analysis proposed in this paper consists of performing "virtual experiments" where the results obtained by means of FE calculations are used as input data for determining the biaxial stress-strain law in agreement with the experimental procedure. In this way, a critical discussion of the experimental procedure can be made, by comparing the "experimental" stress-strain curve (Membrane theory curve) with the "reference" one introduced in the simulations. In particular, the influences of the "(die diameter)/thickness" ratio and of the plastic anisotropy are studied, and limitations of the hydraulic bulge test analysis are discussed.

  15. External Otitis (Swimmer's Ear)

    Science.gov (United States)

    ... to Pneumococcal Vaccine Additional Content Medical News External Otitis (Swimmer's Ear) By Bradley W. Kesser, MD, Associate ... the Outer Ear Ear Blockages Ear Tumors External Otitis (Swimmer's Ear) Malignant External Otitis Perichondritis External otitis ...

  16. Visual outcome and electron microscopic features of indocyanine green-assisted internal limiting membrane peeling from macular hole of various aetiologies

    Directory of Open Access Journals (Sweden)

    Kumar Atul

    2005-01-01

    Full Text Available PURPOSE: To describe the visual outcome of internal limiting membrane (ILM peeling for macular hole of various aetiologies and ultrastructural features of the ILM. MATERIALS AND METHODS: The study was conducted on 40 eyes of 38 patients. Thirty eyes with full thickness macular hole were treated with vitrectomy and removal of ILM. Ten eyes with retinal detachment served as negative controls and these patients underwent vitrectomy and ILM removal. The surgical specimens were examined by transmission electron microscopy. RESULTS: The anatomical success rate of the first operation was 90% in idiopathic and myopic groups, whereas it was 100% in traumatic macular hole group. Visual improvement of ³ two lines was noted in 80% of the cases. Electron microscopy revealed the presence of ILM in all surgical specimens. Proliferation of astrocytes and synthesis of new collagen along the inner surface of ILM was noted in the surgical specimens. CONCLUSION: Our findings suggest that the ILM removal helps in closure of the macular hole and retinal reattachment. Vitrectomy with ILM peeling is a reasonable surgical approach to treat macular holes of idiopathic, myopic and traumatic aetiology.

  17. Evaluation of secondary surgery to enlarge the peeling of the internal limiting membrane following the failed surgery of idiopathic macular holes.

    Science.gov (United States)

    Che, Xin; He, Fanglin; Lu, Linna; Zhu, Dongqing; Xu, Xiaofang; Song, Xin; Fan, Xianqun; Wang, Zhiliang

    2014-03-01

    The aim of the present study was to evaluate the clinical results of pars plana vitrectomy (PPV) combined with the surgical enlargement of internal limiting membrane (ILM) peeling in patients who had previously undergone failed idiopathic macular hole (IMH) surgery. In the study, 134 eyes from 130 IMH patients who had received PPV combined with ILM peeling surgery (2 disk diameters) were analyzed. Within this cohort, 14 eyes had IMHs that were not closed, of which 13 eyes underwent a second surgery involving enlargement of the ILM peeling. The extent of the ILM peeling was increased to the vascular arcades of the posterior fundus in the secondary surgery. Of the 13 eyes that underwent secondary surgery, five were in stage III and nine were in stage IV. The second surgery successfully achieved IMH closure in 61.5% (8/13) of the eyes. The IMH was completely closed following surgery and the logMAR vision increased from 0.98 to 0.84 (P=0.013) in the 8 successfully treated cases. The surgical enlargement of ILM peeling closed the IMHs and improved vision in the majority of patients. In addition, the procedures were safe. Therefore, the results of the present study indicate that enlargement of ILM peeling may be an effective therapy for patients who have previously undergone the failed surgical correction of an IMH.

  18. Successful closure of treatment-naïve, flat edge (Type II, full-thickness macular hole using inverted internal limiting membrane flap technique

    Directory of Open Access Journals (Sweden)

    Hussain N

    2016-10-01

    Full Text Available Nazimul Hussain,1 Anjli Hussain2 1Department of Ophthalmology, Al Zahra Hospital, 2Al Zahra Medical Center, Dubai, United Arab Emirates Objective: The objective of this study was to present the outcome of the internal limiting membrane (ILM peeling flap technique for a treatment-naïve, flat edge (Type II, full-thickness macular hole (MH. Methods: A 52-year-old man presented with complaints of decreased vision and seeing black spot. He was diagnosed to have a flat edge, full-thickness MH, which was confirmed by optical coherence tomography (OCT. He underwent 23G vitrectomy with brilliant blue G-assisted inverted ILM peeling with an inverted flap over the hole followed by fluid gas exchange. Results: Postoperative follow-up until 3 months showed successful closure of the MH, which was confirmed by OCT. The best-corrected visual acuity improved from baseline 6/60 to 6/12 at the final follow-up. Conclusion: Using the inverted ILM flap technique, a treatment-naïve, flat edge (Type II, full thickness MH achieved successful anatomical and functional outcomes. Keywords: macular hole, inverted ILM, optical coherence tomography

  19. Antibiotics and iron-limiting conditions and their effect on the production and composition of outer membrane vesicles secreted from clinical isolates of extraintestinal pathogenic E. coli.

    Science.gov (United States)

    Chan, Kin W; Shone, Clifford; Hesp, J Richard

    2017-01-01

    The focus of this study was to characterize the effect of clinically relevant stress-inducing conditions on the production and composition of proinflammatory outer membrane vesicles (OMVs) produced from ST131 extraintestinal pathogenic Escherichia coli (ExPEC) clinical isolates. A label-free method (relative normalized spectral index quantification, SINQ) was used to identify changes in the respective OMV proteomes following exposure of the ExPEC strains to antibiotics and low iron. Nanoparticle tracking analysis was used to quantify changes in abundance and size of OMVs produced by the gentamicin-resistant (GenR) and gentamicin-sensitive (GenS) ExPEC strains. Up to a 13.1-fold increase in abundance of particles were detected when the gentamicin-sensitive strain was exposed to a range of gentamicin concentrations. In contrast, no increase was observed for the gentamicin-resistant strain. Iron-limiting conditions had minimal effect on OMV production for either strain. Marked changes in the OMV proteome were observed for both strains including increases in Hsp100/Clp proteins, ATP-dependent ClpP protease, and regulatory proteins. These data provide information on changes in the composition of OMV particles derived from ExPEC strains generated in response to clinically relevant conditions. We show that the levels of the proinflammatory OMVs increase for gentamicin-sensitive ExPEC exposed to the antibiotic. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  20. External Fixation Combined with Limited Internal Fixation for the Treatment of Tile C Type Pelvic Fracture%外固定联合有限内固定治疗Tile C型骨盆骨折

    Institute of Scientific and Technical Information of China (English)

    李琳

    2014-01-01

    Objective To explore the clinical effects of the external fixation combined with limited internal fixation in the treatment of Tile C type pelvic fracture. Methods 27 patients of Tile C type pelvic fracture were administrated with external fixation combined with limited internal fixation. 25 of the 27 patients were followed up. There were 17 patients of Tile C1pelvic fracture;8 patients of Tile C2 pelvic fracture. Results 25 patient were followed up for 6 months to 2 year( average,1. 5 years). According to Tornetta standard evaluation score after reduction of fracture,the results were excellent in 12 cases,good in 9 cases,fair in 3 cases and bad in 1 cases. The total excellent and good rate was 84%. According to Majeed score system af-ter the postoperative functional recovery,the results were excellent in 11 cases,good in 11 cases,fair in 2 cases and bad in 1 cases,the total excellent and good rate was 88%. Conclusion External fixation combined with limited internal fixation can not only restore pelvic ring continuity and overall stability of structure but also have mang advantages,such as practical,effective operation,small trauma,less bleeding,convenient adjustment and disassemble. The methods is worthy of wide application.%目的:探究外固定联合有限内固定治疗Tile C型骨盆骨折的临床疗效。方法对27例Tile C型骨盆骨折采用外固定支架联合有限内固定进行治疗,本组27例,25例获得随访,根据Tile分型,C1型17例,C2型8例。结果本组随访时间为6个月~2年,平均1.5年。骨盆骨折复位后根据Tornetta评分标准评价,优12例,良9例,可3例,差1例,总体优良率为84%;术后功能恢复情况采用MaJeed评分系统评价,优11例,良11例,中2例,差1例,总体优良率为88%。结论对于Tile C型骨盆骨折,采用外固定联合有限内固定双重固定不仅可以恢复骨盆环解剖序列的连续性和整体结构的稳定性,而且该方法具有实

  1. The External Degree.

    Science.gov (United States)

    Houle, Cyril O.

    This book examines the external degree in relation to the extremes of attitudes, myths, and data. Emphasis is placed on the emergence of the American external degree, foreign external-degree programs, the purpose of the external degree, the current scene, institutional issues, and problems of general policy. (MJM)

  2. Thermodynamic cost of external control

    Science.gov (United States)

    Barato, Andre C.; Seifert, Udo

    2017-07-01

    Artificial molecular machines are often driven by the periodic variation of an external parameter. This external control exerts work on the system of which a part can be extracted as output if the system runs against an applied load. Usually, the thermodynamic cost of the process that generates the external control is ignored. Here, we derive a refined second law for such small machines that include this cost, which is, for example, generated by free energy consumption of a chemical reaction that modifies the energy landscape for such a machine. In the limit of irreversible control, this refined second law becomes the standard one. Beyond this ideal limiting case, our analysis shows that due to a new entropic term unexpected regimes can occur: the control work can be smaller than the extracted work and the work required to generate the control can be smaller than this control work. Our general inequalities are illustrated by a paradigmatic three-state system.

  3. Effect of macroporous adsorption resin-membrane bioreactor hybrid system against fouling for municipal wastewater treatment.

    Science.gov (United States)

    Chen, Weiwei; Luo, Jing; Cao, Ruyi; Li, Yuting; Liu, Jinrong

    2017-01-01

    Membrane bioreactor (MBR) displays significant advantages in effluent quality, sludge production, footprint, and operation. However, membrane fouling limits the application of MBR. This study investigated membrane fouling in a macroporous adsorption resin-membrane bioreactor hybrid system established by adding macroporous adsorption resin (MAR) into MBR. MAR addition increased the critical flux by 27.97%, indicating that membrane fouling was successfully mitigated. Consequently, comparative experiments were designed to analyze the pathway. MAR addition mitigated external fouling development and improved mixed liquor characteristics, thereby mitigating gel layer formation and sludge floc deposition on the membrane surface. MAR effectively reduced the supernatant viscosity and dissolved COD by adsorbing soluble microbial products. Sludge production decreased because the sludge activity in MAR-MBR was inhibited. The fouled MAR could be regenerated effectively by deionized water and chemical cleaning. This work demonstrated the feasibility of using MAR-MBR to mitigate fouling in municipal wastewater treatment. Copyright © 2016 Elsevier Ltd. All rights reserved.

  4. Effect of Mass-Transport Limitations on the Performance of a Packed Bed Membrane Reactor for Partial Oxidations. Intraparticle Mass Transport

    NARCIS (Netherlands)

    Sint Annaland, van M.; Kürten, U.; Kuipers, J.A.M.

    2007-01-01

    For partial oxidation systems, where the reaction order in oxygen of the formation rate of the target product is smaller than the reaction order in oxygen of the consecutive reaction rate toward the waste product, a packed bed membrane reactor can be applied to distributively dose oxygen along the r

  5. Limited internal fixation combined with external fixation for comminuted humerus shaft fractures%有限内固定结合外固定支架治疗肱骨干粉碎性骨折

    Institute of Scientific and Technical Information of China (English)

    黄俊武; 周玉龙; 周一飞; 李振兴; 石成弟; 郭晓山

    2016-01-01

    Objective To evaluate the clinical outcome in the treatment of humerus shaft comminuted fractures using limited open reduction and internal fixation combined with an external fixator.Methods Data of 80 patients with comminuted humerus shaft fractures treated from January 2005 to January 2013 were analysed retrospectively.All the patients underwent limited open reduction and internal fixation combined with an external fixator (treatment group) and open reduction and plate fixation (control group) according to the random number table.In the treatment group,there were 40 patients (28 males,12 females),at mean age of 33.5 years (range,21-54 years),with causes of injury including traffic accidents in five patients,falls in nine,crashes in seven and others in six.There were seven patients with open fractures and 33 with closed fractures.In the control group,there were 40 patients (25 males,15 females),at mean age of 32.9 years (range,19-55 years),with causes of injury including traffic accidents in 16 patients,tumbling in seven,crush in seven and others in ten.There were eight patients with open fractures and 32 with closed fractures.The operation time,intraoperative blood loss,bone union time and complications in both groups were recorded.Clinical efficacy was evaluated using the Stewart and Hundley standard.Results Mean follow-up was 19 months (range,15-24 months).Treatment and control groups showed significant differences in operation time [(55.5 ± 10.3) minutes vs.(120.5 ± 15.3) minutes],intraoperative blood loss [(120.4 ± 20.7) ml vs.(245.4 ± 26.7) ml] and bone union time [(11.6 ± 1.3) weeks vs.(14.9 ± 2.3) weeks] (P < 0.05).Rate of incision infection was 8% (3/40) in treatment group and 10% (4/40) in control group (P > 0.05).In treatment group the results were excellent in 31 patients and good in nine.In control group the results were excellent in 27 patients,good in nine,fair in one and poor in three.One patient with radial nerve injury after a

  6. Regulating multiple externalities

    DEFF Research Database (Denmark)

    Waldo, Staffan; Jensen, Frank; Nielsen, Max

    2016-01-01

    Open access is a well-known externality problem in fisheries causing excess capacity and overfishing. Due to global warming, externality problems from CO2 emissions have gained increased interest. With two externality problems, a first-best optimum can be achieved by using two regulatory instrume......Open access is a well-known externality problem in fisheries causing excess capacity and overfishing. Due to global warming, externality problems from CO2 emissions have gained increased interest. With two externality problems, a first-best optimum can be achieved by using two regulatory...

  7. Effectiveness Factors and Conversion in a Biocatalytic Membrane Reactor.

    Science.gov (United States)

    Godongwana, Buntu

    2016-01-01

    Analytical expressions of the effectiveness factor of a biocatalytic membrane reactor, and its asymptote as the Thiele modulus becomes large, are presented. The evaluation of the effectiveness factor is based on the solution of the governing equations for solute transport in the two regions of the reactor, i.e. the lumen and the matrix (with the biofilm immobilized in the matrix). The lumen solution accounts for both axial diffusion and radial convective flow, while the matrix solution is based on Robin-type boundary conditions. The effectiveness factor is shown to be a function of the Thiele modulus, the partition coefficient, the Sherwood number, the Peclet number, and membrane thickness. Three regions of Thiele moduli are defined in the effectiveness factor graphs. These correspond with reaction rate limited, internal-diffusion limited, and external mass transfer limited solute transport. Radial convective flows were shown to only improve the effectiveness factor in the region of internal diffusion limitation. The assumption of first order kinetics is shown to be applicable only in the Thiele modulus regions of internal and external mass transfer limitation. An iteration scheme is also presented for estimating the effectiveness factor when the solute fractional conversion is known. The model is validated with experimental data from a membrane gradostat reactor immobilised with Phanerochaete chrysosporium for the production of lignin and manganese peroxidases. The developed model and experimental data allow for the determination of the Thiele modulus at which the effectiveness factor and fractional conversion are optimal.

  8. ASH External Web Portal (External Portal) -

    Data.gov (United States)

    Department of Transportation — The ASH External Web Portal is a web-based portal that provides single sign-on functionality, making the web portal a single location from which to be authenticated...

  9. Membrane dynamics

    DEFF Research Database (Denmark)

    Bendix, Pól Martin

    2015-01-01

    Current topics include membrane-protein interactions with regard to membrane deformation or curvature sensing by BAR domains. Also, we study the dynamics of membrane tubes of both cells and simple model membrane tubes. Finally, we study membrane phase behavior which has important implications...... for the lateral organization of membranes as wells as for physical properties like bending, permeability and elasticity...

  10. Comment on "Cholesterol solubility limit in lipid membranes probed by small angle neutron scattering and MD simulations" by S. Garg et al., Soft Matter, 2014, 10, 9313.

    Science.gov (United States)

    Epand, Richard M; Bach, Diana; Wachtel, Ellen

    2015-07-21

    In a recent article, Garg et al. used neutron scattering techniques to determine the limiting amount of cholesterol which vesicles of either POPS or POPC can accommodate. This amount was called "the cholesterol solubility limit". In light of extensive literature on cholesterol phase separation in phospholipid bilayers, the way in which "solubility limit" is defined in this article and the conclusions derived are misleading and require some clarification.

  11. Understanding the Effects of Compression and Constraints on Water Uptake of Fuel-Cell Membranes

    Energy Technology Data Exchange (ETDEWEB)

    Kusoglu, Ahmet; Kienitz, Brian L.; Weber, Adam Z.

    2011-01-01

    Accurate characterization of polymer-electrolyte fuel cells (PEFCs) requires understanding the impact of mechanical and electrochemical loads on cell components. An essential aspect of this relationship is the effect of compression on the polymer membrane?s water-uptake behavior and transport properties. However, there is limited information on the impact of physical constraints on membrane properties. In this paper, we investigate both theoretically and experimentally how the water uptake of Nafion membrane changes under external compression loads. The swelling of a compressed membrane is modeled by modifying the swelling pressure in the polymer backbone which relies on the changes in the microscopic volume of the polymer. The model successfully predicts the water content of the compressed membrane measured through in-situ swelling-compression tests and neutron imaging. The results show that external mechanical loads could reduce the water content and conductivity of the membrane, especially at lower temperatures, higher humidities, and in liquid water. The modeling framework and experimental data provide valuable insight for the swelling and conductivity of constrained and compressed membranes, which are of interest in electrochemical devices such as batteries and fuel cells.

  12. Pseudo-2D polarization model of polymer exchange membrane fuel cell including mass transport limitation due to flooding : numerical simulation and comparison with experimental results

    Energy Technology Data Exchange (ETDEWEB)

    Maranzana, G.; Chupin, S.; Colinart, T.; Lottin, O.; Didierjean, S. [Nancy-Univ., Vandoeuvre (France). Laboratoire d' Energetique et de Mecanique Theorique et Appliquee

    2007-07-01

    The electrodes of proton membrane exchange (PEM) fuel cells are fed by gases, whose properties are changing during their transition from the inlet to the outlet of the channels. For example, the reactant concentration decreases and the water concentration increases, the total pressure diminishes, the temperature is dependent on the local current density, and liquid water may appear or disappear. The electrode performances are not uniform, which can have impacts on the entire performances of the cell or on its durability. In order to observe and model these non-homogeneities, this paper presented an experimental study that involved designing, building, and testing a single PEM fuel cell that allowed measurement of both current density and temperature fields along the gas channels. The fuel cell was made of transparent polymethyl methacrylate (PMMA) so that the location of liquid water appearance in the channels could be observed. The first experimental results were compared with the predictions of a pseudo-2D model which assumed mass transfer to occur in the direction perpendicular to the membrane, but took into account the variations in concentrations, in total pressure, and in temperatures along the gas channels. It was concluded that the current density distribution depended greatly on water management. 10 refs., 3 figs.

  13. Performance limiting effects in power generation from salinity gradients by pressure retarded osmosis.

    Science.gov (United States)

    Yip, Ngai Yin; Elimelech, Menachem

    2011-12-01

    Pressure retarded osmosis has the potential to utilize the free energy of mixing when fresh river water flows into the sea for clean and renewable power generation. Here, we present a systematic investigation of the performance limiting phenomena in pressure retarded osmosis--external concentration polarization, internal concentration polarization, and reverse draw salt flux--and offer insights on the design criteria of a high performance pressure retarded osmosis power generation system. Thin-film composite polyamide membranes were chemically modified to produce a range of membrane transport properties, and the water and salt permeabilities were characterized to determine the underlying permeability-selectivity trade-off relationship. We show that power density is constrained by the trade-off between permeability and selectivity of the membrane active layer. This behavior is attributed to the opposing influence of the beneficial effect of membrane water permeability and the detrimental impact of reverse salt flux coupled with internal concentration polarization. Our analysis reveals the intricate influence of active and support layer properties on power density and demonstrates that membrane performance is maximized by tailoring the water and salt permeabilities to the structural parameters. An analytical parameter that quantifies the relative influence of each performance limiting phenomena is employed to identify the dominant effect restricting productivity. External concentration polarization is shown to be the main factor limiting performance at high power densities. Enhancement of the hydrodynamic flow conditions in the membrane feed channel reduces external concentration polarization and thus, yields improved power density. However, doing so will also incur additional operating costs due to the accompanying hydraulic pressure loss. This study demonstrates that by thoughtful selection of the membrane properties and hydrodynamic conditions, the detrimental

  14. Performance Limiting Effects in Power Generation from Salinity Gradients by Pressure Retarded Osmosis

    KAUST Repository

    Yip, Ngai Yin

    2011-12-01

    Pressure retarded osmosis has the potential to utilize the free energy of mixing when fresh river water flows into the sea for clean and renewable power generation. Here, we present a systematic investigation of the performance limiting phenomena in pressure retarded osmosis-external concentration polarization, internal concentration polarization, and reverse draw salt flux-and offer insights on the design criteria of a high performance pressure retarded osmosis power generation system. Thin-film composite polyamide membranes were chemically modified to produce a range of membrane transport properties, and the water and salt permeabilities were characterized to determine the underlying permeability-selectivity trade-off relationship. We show that power density is constrained by the trade-off between permeability and selectivity of the membrane active layer. This behavior is attributed to the opposing influence of the beneficial effect of membrane water permeability and the detrimental impact of reverse salt flux coupled with internal concentration polarization. Our analysis reveals the intricate influence of active and support layer properties on power density and demonstrates that membrane performance is maximized by tailoring the water and salt permeabilities to the structural parameters. An analytical parameter that quantifies the relative influence of each performance limiting phenomena is employed to identify the dominant effect restricting productivity. External concentration polarization is shown to be the main factor limiting performance at high power densities. Enhancement of the hydrodynamic flow conditions in the membrane feed channel reduces external concentration polarization and thus, yields improved power density. However, doing so will also incur additional operating costs due to the accompanying hydraulic pressure loss. This study demonstrates that by thoughtful selection of the membrane properties and hydrodynamic conditions, the detrimental

  15. Chelating polymeric membranes

    KAUST Repository

    Peinemann, Klaus-Viktor

    2015-01-22

    The present application offers a solution to the current problems associated with recovery and recycling of precious metals from scrap material, discard articles, and other items comprising one or more precious metals. The solution is premised on a microporous chelating polymeric membrane. Embodiments include, but are not limited to, microporous chelating polymeric membranes, device comprising the membranes, and methods of using and making the same.

  16. Determination of the gas-to-membrane mass transfer coefficient in a catalytic membrane reactor

    NARCIS (Netherlands)

    Veldsink, J.W.; Versteeg, G.F.; Swaaij, W.P.M. van

    1995-01-01

    A novel method to determine the external mass transfer coefficient in catalytic membrane reactors (Sloot et al., 1992a, b) was presented in this study. In a catalytically active membrane reactor, in which a very fast reaction occurs, the external transfer coefficient can conveniently be measured by

  17. Determination of the gas-to-membrane mass transfer coefficient in a catalytic membrane reactor

    NARCIS (Netherlands)

    Veldsink, J.W.; Versteeg, G.F.; Swaaij, W.P.M. van

    1995-01-01

    A novel method to determine the external mass transfer coefficient in catalytic membrane reactors (Sloot et al., 1992a, b) was presented in this study. In a catalytically active membrane reactor, in which a very fast reaction occurs, the external transfer coefficient can conveniently be measured by

  18. External radiation surveillance

    Energy Technology Data Exchange (ETDEWEB)

    Antonio, E.J.

    1995-06-01

    This section of the 1994 Hanford Site Environmental Report describes how external radiation was measured, how surveys were performed, and the results of these measurements and surveys. External radiation exposure rates were measured at locations on and off the Hanford Site using thermoluminescent dosimeters (TLD). External radiation and contamination surveys were also performed with portable radiation survey instruments at locations on and around the Hanford Site.

  19. Water Membrane Evaporator

    Science.gov (United States)

    Ungar, Eugene K.; Almlie, Jay C.

    2010-01-01

    A water membrane evaporator (WME) has been conceived and tested as an alternative to the contamination-sensitive and corrosion-prone evaporators currently used for dissipating heat from space vehicles. The WME consists mainly of the following components: An outer stainless-steel screen that provides structural support for the components mentioned next; Inside and in contact with the stainless-steel screen, a hydrophobic membrane that is permeable to water vapor; Inside and in contact with the hydrophobic membrane, a hydrophilic membrane that transports the liquid feedwater to the inner surface of the hydrophobic membrane; Inside and in contact with the hydrophilic membrane, an annular array of tubes through which flows the spacecraft coolant carrying the heat to be dissipated; and An inner exclusion tube that limits the volume of feedwater in the WME. In operation, a pressurized feedwater reservoir is connected to the volume between the exclusion tube and the coolant tubes. Feedwater fills the volume, saturates the hydrophilic membrane, and is retained by the hydrophobic membrane. The outside of the WME is exposed to space vacuum. Heat from the spacecraft coolant is conducted through the tube walls and the water-saturated hydrophilic membrane to the liquid/vapor interface at the hydrophobic membrane, causing water to evaporate to space. Makeup water flows into the hydrophilic membrane through gaps between the coolant tubes.

  20. External NAD(P)H dehydrogenases in Acanthamoeba castellanii mitochondria.

    Science.gov (United States)

    Antos-Krzeminska, Nina; Jarmuszkiewicz, Wieslawa

    2014-09-01

    The mitochondrial respiratory chain of plants and some fungi contains multiple rotenone-insensitive NAD(P)H dehydrogenases, of which at least two are located on the outer surface of the inner membrane (i.e., external NADH and external NADPH dehydrogenases). Annotated sequences of the putative alternative NAD(P)H dehydrogenases of the protozoan Acanthamoeba castellanii demonstrated similarity to plant and fungal sequences. We also studied activity of these dehydrogenases in isolated A. castellanii mitochondria. External NADPH oxidation was observed for the first time in protist mitochondria. The coupling parameters were similar for external NADH oxidation and external NADPH oxidation, indicating similar efficiencies of ATP synthesis. Both external NADH oxidation and external NADPH oxidation had an optimal pH of 6.8 independent of relevant ubiquinol-oxidizing pathways, the cytochrome pathway or a GMP-stimulated alternative oxidase. The maximal oxidizing activity with external NADH was almost double that with external NADPH. However, a lower Michaelis constant (K(M)) value for external NADPH oxidation was observed compared to that for external NADH oxidation. Stimulation by Ca(2+) was approximately 10 times higher for external NADPH oxidation, while NADH dehydrogenase(s) appeared to be slightly dependent on Ca(2+). Our results indicate that external NAD(P)H dehydrogenases similar to those in plant and fungal mitochondria function in mitochondria of A. castellanii.

  1. Membrane reactor. Membrane reactor

    Energy Technology Data Exchange (ETDEWEB)

    Shindo, Y.; Wakabayashi, K. (National Chemical Laboratory for Industry, Tsukuba (Japan))

    1990-08-05

    Many reaction examples were introduced of membrane reactor, to be on the point of forming a new region in the field of chemical technology. It is a reactor to exhibit excellent function, by its being installed with membrane therein, and is generally classified into catalyst function type and reaction promotion type. What firstly belongs to the former is stabilized zirconia, where oxygen, supplied to the cathodic side of membrane with voltage, impressed thereon, becomes O {sup 2 {minus}} to be diffused through the membrane and supplied, as variously activated oxygenous species, on the anodic side. Examples with many advantages can be given such as methane coupling, propylene oxidation, methanating reaction of carbon dioxide, etc. Apart, palladium film and naphion film also belong to the former. While examples of the latter comprise, among others, decomposition of hydrogen sulfide by porous glass film and dehydrogenation of cyclohexane or palladium alloy film, which are expected to be developed and materialized in the industry. 33 refs., 8 figs.

  2. Mesoporous and microporous titania membranes

    NARCIS (Netherlands)

    Sekulic-Kuzmanovic, Jelena

    2004-01-01

    The research described in this thesis deals with the synthesis and properties of ceramic oxide membrane materials. Since most of the currently available inorganic membranes with required separation properties have limited reliability and long-term stability, membranes made of new oxide materials tha

  3. Lesions in the external auditory canal

    Directory of Open Access Journals (Sweden)

    Priyank S Chatra

    2011-01-01

    Full Text Available The external auditory canal is an S- shaped osseo-cartilaginous structure that extends from the auricle to the tympanic membrane. Congenital, inflammatory, neoplastic, and traumatic lesions can affect the EAC. High-resolution CT is well suited for the evaluation of the temporal bone, which has a complex anatomy with multiple small structures. In this study, we describe the various lesions affecting the EAC.

  4. Biobased Membrane

    NARCIS (Netherlands)

    Koenders, E.A.B.; Zlopasa, J.; Picken, S.J.

    2015-01-01

    The present invention is in the field of a composition for forming a bio-compatible membrane applicable to building material, such as concrete, cement, etc., to a meth od of applying said composition for forming a bio-compatible membrane, a biocompatible membrane, use of said membrane for various pu

  5. Membrane fusion

    DEFF Research Database (Denmark)

    Bendix, Pól Martin

    2015-01-01

    At Stanford University, Boxer lab, I worked on membrane fusion of small unilamellar lipid vesicles to flat membranes tethered to glass surfaces. This geometry closely resembles biological systems in which liposomes fuse to plasma membranes. The fusion mechanism was studied using DNA zippering...... between complementary strands linked to the two apposing membranes closely mimicking the zippering mechanism of SNARE fusion complexes....

  6. Consumption Externalities, Rental Markets and Purchase Clubs.

    OpenAIRE

    Suzanne Scotchmer

    2002-01-01

    A premise of general equilibrium theory is that private goods are rival. Nevertheless, many private goods are shared, e.g., through barter, through co-ownership, or simply because one person’s consumption affects another person’s wellbeing. We analyze consumption externalities from the perspective of club theory, and argue that, provided consumption externalities are limited in scope, they can be internalized through membership fees to groups. Our main applications are to rental markets and “...

  7. External Prestressing Bridge Reinforcement Technology Review

    Directory of Open Access Journals (Sweden)

    Zhu Hanbing

    2015-01-01

    Full Text Available Externally prestressed bridge can not only limit and reduce the cracks and deformation of the structure, improve the rigidity and bearing capacity of structure, improve the stress state of structure, but also have less interference for bridge operation when it is operating and have the good economic efficiency. This paper introduces the advantages and disadvantages of external prestressed strengthening technique, its calculation theory and construction technology described in detail, and finally the paper discusses the deficiency of existing research.

  8. Externally Verifiable Oblivious RAM

    Directory of Open Access Journals (Sweden)

    Gancher Joshua

    2017-04-01

    Full Text Available We present the idea of externally verifiable oblivious RAM (ORAM. Our goal is to allow a client and server carrying out an ORAM protocol to have disputes adjudicated by a third party, allowing for the enforcement of penalties against an unreliable or malicious server. We give a security definition that guarantees protection not only against a malicious server but also against a client making false accusations. We then give modifications of the Path ORAM [15] and Ring ORAM [9] protocols that meet this security definition. These protocols both have the same asymptotic runtimes as the semi-honest original versions and require the external verifier to be involved only when the client or server deviates from the protocol. Finally, we implement externally verified ORAM, along with an automated cryptocurrency contract to use as the external verifier.

  9. External Beam Therapy (EBT)

    Science.gov (United States)

    ... Esophageal Cancer Treatment Head and Neck Cancer Treatment Lung Cancer Treatment Prostate Cancer Treatment Brain Tumor Treatment Why is ... Radiation Oncology) Breast Cancer Treatment Esophageal Cancer Treatment Lung Cancer Treatment Images related to External Beam Therapy (EBT) Sponsored ...

  10. MALIGNANT EXTERNAL OTITIS

    OpenAIRE

    Massoud Moghaddam

    1993-01-01

    Two case reports of malignant external otitis in the elderly diabetics and their complications and management with regard to our experience at Amir Alam Hospital, Department of ENT will be discussed here.

  11. Checklists for external validity

    DEFF Research Database (Denmark)

    Dyrvig, Anne-Kirstine; Kidholm, Kristian; Gerke, Oke;

    2014-01-01

    RATIONALE, AIMS AND OBJECTIVES: The quality of the current literature on external validity varies considerably. An improved checklist with validated items on external validity would aid decision-makers in judging similarities among circumstances when transferring evidence from a study setting...... to an implementation setting. In this paper, currently available checklists on external validity are identified, assessed and used as a basis for proposing a new improved instrument. METHOD: A systematic literature review was carried out in Pubmed, Embase and Cinahl on English-language papers without time restrictions....... The retrieved checklist items were assessed for (i) the methodology used in primary literature, justifying inclusion of each item; and (ii) the number of times each item appeared in checklists. RESULTS: Fifteen papers were identified, presenting a total of 21 checklists for external validity, yielding a total...

  12. Migration with fiscal externalities.

    Science.gov (United States)

    Hercowitz, Z; Pines, D

    1991-11-01

    "This paper analyses the distribution of a country's population among regions when migration involves fiscal externalities. The main question addressed is whether a decentralized decision making [by] regional governments can produce an optimal population distribution...or a centralized intervention is indispensable, as argued before in the literature.... It turns out that, while with costless mobility the fiscal externality is fully internalized by voluntary interregional transfers, with costly mobility, centrally coordinated transfers still remain indispensable for achieving the socially optimal allocation."

  13. Sen cycles and externalities

    OpenAIRE

    Piggins, Ashley; Salerno, Gillian

    2016-01-01

    It has long been understood that externalities of some kind are responsible for Sen’s (1970) theorem on the impossibility of a Paretian liberal. However, Saari and Petron (2006) show that for any social preference cycle generated by combining the weak Pareto principle and individual decisiveness, every decisive individual must suffer at least one strong negative externality. We show that this fundamental result only holds when individual preferences are strict. Building on their contribution,...

  14. 有限内固定结合外固定架治疗Rüedi-Allg(o)wer Ⅲ型Pilon骨折%Limited internal fixation combining with external fixation for the treatment of Rüedi-Allg wer Ⅲ Pilon fractures

    Institute of Scientific and Technical Information of China (English)

    廖伟; 王玉龙; 姬彦辉; 滕宇; 郑启新; 兰生辉

    2012-01-01

    目的 探讨有限内固定结合外固定支架治疗Rüedi-Allg werⅢ型Pilon 骨折的临床疗效.方法 2006 年3月~2010 年7月采用克氏针或螺钉内固定结合外固定支架固定治疗Rüedi-Allg werⅢ型pi1on 骨折18 例,术后2~3 个月拆除外固定支架.结果 术后18 例均获得随访.随访时间4~26 个月,平均15 个月,临床疗效满意,无切口、伤口感染,无皮肤坏死等严重并发症.参照Mazur 踝关节评分分级系统来评价,结果显示优6例,良9例,可3 例,总体优良率达约83.3%.结论 有限内固定结合外固定支架能有效固定骨折端,避免软组织感染和骨不连,是治疗严重粉碎Pilon骨折理想的方法之一.%Objective To investigate the clinical effect of treatment of Riiedi-Allgo2er IllPilon' s fractures with limited internal fixations and external fixators. Methods 18 cases of Riiedi-AllgowerlllPilon' s fractures with limited internal fixations and external fixators were treated during 2006 to 2010. They were all treated by Kirss-chnerwires or screws together with external fixations. External fixator were removed at 2 to 3 monks after operation. Results All cases were followed up after operation. The following observation time was 4 to 26 months, average 15 months. No infections of wound and incision, no skin necrosis complication was found. According to Mazur ankle joint scoring system, The results demonstrated 6 excellent, 9 good, 3 fair, the excellent and good rate was 83.3%. Conclusion Limited internal fixation and external fixator is one of the effective way of treatment of Pilon III fracture because it can immobilize the sections of fracture and avoid infection of soft tissue and nonunion of fracture.

  15. Leveraging External Sources of Innovation

    DEFF Research Database (Denmark)

    West, Joel; Bogers, Marcel

    2014-01-01

    own specific set of mechanisms and conditions. Integrating innovations has been mostly studied from an absorptive capacity perspective, with less attention given to the impact of competencies and culture (including “not invented here”). Commercializing innovations puts the most emphasis on how......” in a way inconsistent with earlier definitions in innovation management. The paper concludes with recommendations for future research that include examining the end-to-end innovation commercialization process, and studying the moderators and limits of leveraging external sources of innovation....

  16. Clinical experience of the treatment of comminuted fracture of tibia and fibula with limited internal fixation and external fixation%克氏针有限内固定加外固定支架治疗胫腓骨远端粉碎性骨折的临床体会

    Institute of Scientific and Technical Information of China (English)

    严海兵

    2015-01-01

    Objective:To investigate the therapeutic effect of Ke pin limited fixed and external fixation bracket in the treatment of comminuted fracture of distal tibia and fibula.Methods:140 patients with comminuted fracture of distal tibia and fibula were divided into the observation group and the control group.They used the Ke pin limited fixed+external fixation bracket treatment and the open reduction and locking plate internal fixation treatment respectively.Results:The two groups had no differents in operation time,hospitalization time and complications (P<0.05).Conclusion:Ke pin limited fixed and external fixation bracket in the treatment of comminuted fracture of distal tibia and fibula has small trauma,good recovery,less cost,easy to operate,safe and effective.%目的:探讨采用克氏针有限固定加外固定支架治疗胫腓骨远端粉碎性骨折的疗效。方法:将140例胫腓骨远端粉碎性骨折患者分为观察组和对照组,分别采用克氏针有限固定加外固定支架和切开复位锁定钢板内固定。结果:两组在手术时间、住院时间和并发症方面比较,差异有统计学意义(P<0.05)。结论:采用克氏针有限固定加+外固定支架治疗胫腓骨远端粉碎性骨折,创伤小、恢复好、花费少,操作简便,安全,有效。

  17. Comparative Evaluation of Retinal Nerve Fiber Layer Thickness After Conventional Brilliant Blue Assisted Internal Limiting Membrane Peeling Versus Brilliant Blue Selective Staining Using Whole Blood in Macular Hole Surgery.

    Science.gov (United States)

    Arora, Supriya; Goel, Neha; Arora, Tarun; Sharma, Prateeksha; Raina, Usha Kaul; Thakar, Meenakshi; Ghosh, Basudeb

    2016-05-01

    To evaluate retinal nerve fiber layer (RNFL) thickness after conventional brilliant blue (BB) assisted macular hole (MH) surgery versus BB selective staining using whole blood (WB) in MH surgery. Sixty eyes with stage 4 idiopathic MH with a clear media were randomly divided into two equal groups. Group A eyes underwent sequential intraoperative use of autologous heparinized WB followed by BB dye for staining internal limiting membrane, whereas eyes in group B were subjected to conventional BB staining. Clinical examination and spectral-domain optical coherence tomography was done preoperatively and postoperatively up to 6 months. Mean global RNFL thickness and mean temporal RNFL thickness decreased in both groups postoperatively, but the reduction in RNFL thickness in group B was greater than group A at all postoperative visits (P < .05). BB toxicity may be responsible for reduction of RNFL thickness and WB appears to protect RNFL against dye toxicity. [Ophthalmic Surg Lasers Imaging Retina. 2016;47:436-442.]. Copyright 2016, SLACK Incorporated.

  18. Environmental external effects from wind power based on the EU ExternE methodology

    DEFF Research Database (Denmark)

    Ibsen, Liselotte Schleisner; Nielsen, Per Sieverts

    1998-01-01

    The European Commission has launched a major study project, ExternE, to develop a methodology to quantify externalities. A “National Implementation Phase”, was started under the Joule II programme with the purpose of implementing the ExternE methodology in all member states. The main objective...

  19. Externality or sustainability economics?

    Energy Technology Data Exchange (ETDEWEB)

    Bergh, Jeroen C.J.M. van den [ICREA, Barcelona (Spain); Department of Economics and Economic History and Institute for Environmental Science and Technology, Universitat Autonoma de Barcelona (Spain)

    2010-09-15

    In an effort to develop 'sustainability economics' Baumgaertner and Quaas (2010) neglect the central concept of environmental economics-'environmental externality'. This note proposes a possible connection between the concepts of environmental externality and sustainability. In addition, attention is asked for other aspects of 'sustainability economics', namely the distinction weak/strong sustainability, spatial sustainability and sustainable trade, distinctive sustainability policy, and the ideas of early 'sustainability economists'. I argue that both sustainability and externalities reflect a systems perspective and propose that effective sustainability solutions require that more attention is given to system feedbacks, notably other-regarding preferences and social interactions, and energy and environmental rebound. The case of climate change and policy is used to illustrate particular statements. As a conclusion, a list of 20 insights and suggestions for research is offered. (author)

  20. Metasurface external cavity laser

    Energy Technology Data Exchange (ETDEWEB)

    Xu, Luyao, E-mail: luyaoxu.ee@ucla.edu; Curwen, Christopher A.; Williams, Benjamin S. [Department of Electrical Engineering, University of California, Los Angeles, California 90095 (United States); California NanoSystems Institute, University of California, Los Angeles, California 90095 (United States); Hon, Philip W. C.; Itoh, Tatsuo [Department of Electrical Engineering, University of California, Los Angeles, California 90095 (United States); Chen, Qi-Sheng [Northrop Grumman Aerospace Systems, Redondo Beach, California 90278 (United States)

    2015-11-30

    A vertical-external-cavity surface-emitting-laser is demonstrated in the terahertz range, which is based upon an amplifying metasurface reflector composed of a sub-wavelength array of antenna-coupled quantum-cascade sub-cavities. Lasing is possible when the metasurface reflector is placed into a low-loss external cavity such that the external cavity—not the sub-cavities—determines the beam properties. A near-Gaussian beam of 4.3° × 5.1° divergence is observed and an output power level >5 mW is achieved. The polarized response of the metasurface allows the use of a wire-grid polarizer as an output coupler that is continuously tunable.

  1. Membranous nephropathy

    Science.gov (United States)

    ... page: //medlineplus.gov/ency/article/000472.htm Membranous nephropathy To use the sharing features on this page, please enable JavaScript. Membranous nephropathy is a kidney disorder that leads to changes ...

  2. Firing membranes

    NARCIS (Netherlands)

    Kappert, Emiel Jan

    2015-01-01

    Thermal processing is commonly employed to alter the chemistry and microstructure of membrane layers. It can shape, strengthen, and give functionality to a membrane. A good understanding of the processes taking place during the thermal processing of a membrane material allows for optimization and tu

  3. Nanocrack-regulated self-humidifying membranes

    Science.gov (United States)

    Park, Chi Hoon; Lee, So Young; Hwang, Doo Sung; Shin, Dong Won; Cho, Doo Hee; Lee, Kang Hyuck; Kim, Tae-Woo; Kim, Tae-Wuk; Lee, Mokwon; Kim, Deok-Soo; Doherty, Cara M.; Thornton, Aaron W.; Hill, Anita J.; Guiver, Michael D.; Lee, Young Moo

    2016-04-01

    The regulation of water content in polymeric membranes is important in a number of applications, such as reverse electrodialysis and proton-exchange fuel-cell membranes. External thermal and water management systems add both mass and size to systems, and so intrinsic mechanisms of retaining water and maintaining ionic transport in such membranes are particularly important for applications where small system size is important. For example, in proton-exchange membrane fuel cells, where water retention in the membrane is crucial for efficient transport of hydrated ions, by operating the cells at higher temperatures without external humidification, the membrane is self-humidified with water generated by electrochemical reactions. Here we report an alternative solution that does not rely on external regulation of water supply or high temperatures. Water content in hydrocarbon polymer membranes is regulated through nanometre-scale cracks (‘nanocracks’) in a hydrophobic surface coating. These cracks work as nanoscale valves to retard water desorption and to maintain ion conductivity in the membrane on dehumidification. Hydrocarbon fuel-cell membranes with surface nanocrack coatings operated at intermediate temperatures show improved electrochemical performance, and coated reverse-electrodialysis membranes show enhanced ionic selectivity with low bulk resistance.

  4. Limited Internal Fixation Combined External Fixator in the Treatment of Open Fractures of Tibia and Fibula%有限内固定结合组合式外固定架治疗胫腓骨开放性骨折

    Institute of Scientific and Technical Information of China (English)

    许明友; 江深河

    2014-01-01

    Objective To summarize the experience of limited internal fixation combined external fixation in open fractures of tibia and fibula in the treatment of clinical ef icacy. Methods I Division in 2009 September~2013 year in December the use of limited internal fixation combined external fixation for the treatment of open fractures of tibia and fibula in 53 cases. Results 53 cases of fracture healing. Conclusion The fixation is reliable, simple operation, less injury, wound infection risk reduction advantages, has high clinical application value.%目的:总结有限内固定结合组合式外固定在胫腓骨开放性骨折治疗过程中的临床疗效。方法我科于2009年9月~2013年12月使用有限内固定结合组合式外固定治疗胫腓骨开放性骨折53例。结果53例骨折均愈合。结论固定可靠,操作简单、手术损伤较小,伤口感染风险降低等优点,具有较高的临床运用价值。

  5. Stochastic Control - External Models

    DEFF Research Database (Denmark)

    Poulsen, Niels Kjølstad

    2005-01-01

    This note is devoted to control of stochastic systems described in discrete time. We are concerned with external descriptions or transfer function model, where we have a dynamic model for the input output relation only (i.e.. no direct internal information). The methods are based on LTI systems...

  6. Productivity Change and Externalities

    DEFF Research Database (Denmark)

    Kravtsova, Victoria

    2014-01-01

    firms and the economy as a whole. The approach used in the current research accounts for different internal as well as external factors that individual firms face and evaluates the effect on changes in productivity, technology as well as the efficiency of domestic firms. The empirical analysis focuses...... change in different types of firms and sectors of the economy...

  7. Multiple external root resorption.

    Science.gov (United States)

    Yusof, W Z; Ghazali, M N

    1989-04-01

    Presented is an unusual case of multiple external root resorption. Although the cause of this resorption was not determined, several possibilities are presented. Trauma from occlusion, periodontal and pulpal inflammation, and resorption of idiopathic origin are all discussed as possible causes.

  8. The effect of external betaine on membrane lipid peroxidation of wheat seedling under water stress%外源甜菜碱对干旱胁迫下小麦幼苗膜脂过氧化作用的影响

    Institute of Scientific and Technical Information of China (English)

    孙文越; 王辉; 黄久常

    2001-01-01

    用PEG4000溶液对小麦(Triticum aestivum L.heimang)幼苗进行胁迫处理和加入外源甜菜碱(Betaine)作同样处理,6、12、18和24 h测定生理变化。结果表明,与对照相比,外源甜菜碱导致小麦幼苗叶片含水量下降,相对膜透性增大,MDA含量升高,SOD和POD活性先降后增,同时脯氨酸大量积累。说明外源甜菜碱对小麦幼苗受伤害程度有明显加深作用。%Using solution of PEG4000 to deal with wheat (Triticum aestivum L.heimang) seedling as control,we add betaine to solution of PEG4000 to deal with wheat seedling for spans of 6 hours,12 hours,18 hours and 24 hours,and determine the physiological changes in leaves of wheat seedling.The results indicated that,making all possible comparisons with control,treating wheat seedling with solution of external betaine and PEG4000 decreased the water content of wheat seedling leaves,increased the membrane relative permeability of wheat seedling leaves;increased the content of MDA of wheat seedling leaves,decreased the activities of SOD and POD of wheat seeding leaves at first,then increased them;at the same time,led to large accumulation of proline of wheat seeding leaves.Conclusively,external betaine can enhances the degree of injury of wheat seedling.

  9. Membrane Biophysics

    CERN Document Server

    Ashrafuzzaman, Mohammad

    2013-01-01

    Physics, mathematics and chemistry all play a vital role in understanding the true nature and functioning of biological membranes, key elements of living processes. Besides simple spectroscopic observations and electrical measurements of membranes we address in this book the phenomena of coexistence and independent existence of different membrane components using various theoretical approaches. This treatment will be helpful for readers who want to understand biological processes by applying both simple observations and fundamental scientific analysis. It provides a deep understanding of the causes and effects of processes inside membranes, and will thus eventually open new doors for high-level pharmaceutical approaches towards fighting membrane- and cell-related diseases.

  10. Ocean thermocline driven membrane distillation process

    KAUST Repository

    Francis, Lijo

    2017-07-20

    Systems and methods using membrane distillation are provided for desalinating water, for example for the production of potable water, to address freshwater requirements. In an aspect the systems and methods do not require applying an external heat source, or the energy cost of the heating source, to heat the feed stream to the membrane. In an aspect, the sensible heat present in surface seawater is used for the heat energy for the warm stream fed to the membrane, and deep seawater is used as the cold/coolant feed to the membrane to provide the needed temperature gradient or differential across the membrane.

  11. Effects of external potassium (k supply on drought tolerances of two contrasting winter wheat cultivars.

    Directory of Open Access Journals (Sweden)

    Jiguang Wei

    Full Text Available BACKGROUND: Drought is a common stress limiting crops growth and productivities worldwide. Water deficit may increase cellular membrane permeability, resulting in K outflow. Internal K starvation may disorder plant metabolism and limit plant growth. However, it is seldom reported about the effects of external K on drought tolerance of contrasting wheat cultivars. METHODOLOGY/PRINCIPAL FINDINGS: A hydroponics experiment was carried out in a non-controlled greenhouse. Seedlings of drought-tolerant SN16 and intolerant JM22 were simultaneously treated by five levels of K2CO3 (0, 2.5, 5, 7.5, 10 mM and two levels of PEG6000 (0, 20% for 7 days. External K2CO3 significantly increased shoot K(+ content, water potential, chlorophyll content as well as gas exchange, but decreased electrolyte leakage (EL and MDA content in both cultivars under PEG6000 stress. Antioxidant enzymes activities were up-regulated by PEG6000 while external K2CO3 reduced those changes. Molecular basis was explained by measuring the expression levels of antioxidant enzymes related genes. Shoot and root biomass were also increased by K2CO3 supply under drought stress. Although adequate K2CO3 application enhanced plant growth for both cultivars under drought stress, SN16 was better than JM22 due to its high drought tolerance. CONCLUSIONS/SIGNIFICANCE: Adequate external K may effectively protect winter wheat from drought injuries. We conclude that drought-tolerant wheat combined with adequate external K supply may be a promising strategy for better growth in arid and semi-arid regions.

  12. ExternE transport methodology for external cost evaluation of air pollution

    DEFF Research Database (Denmark)

    Jensen, S. S.; Berkowicz, R.; Brandt, J.

    The report describes how the human exposure estimates based on NERI's human exposure modelling system (AirGIS) can improve the Danish data used for exposure factors in the ExternE Transport methodology. Initially, a brief description of the ExternE Tranport methodology is given and it is summaris...

  13. The External Mind

    DEFF Research Database (Denmark)

    The External Mind: an Introduction by Riccardo Fusaroli, Claudio Paolucci pp. 3-31 The sign of the Hand: Symbolic Practices and the Extended Mind by Massimiliano Cappuccio, Michael Wheeler pp. 33-55 The Overextended Mind by Shaun Gallagher pp. 57-68 The "External Mind": Semiotics, Pragmatism......, Extended Mind and Distributed Cognition by Claudio Paolucci pp. 69-96 The Social Horizon of Embodied Language and Material Symbols by Riccardo Fusaroli pp. 97-123 Semiotics and Theories of Situated/Distributed Action and Cognition: a Dialogue and Many Intersections by Tommaso Granelli pp. 125-167 Building...... Action in Public Environments with Diverse Semiotic Resources by Charles Goodwin pp. 169-182 How Marking in Dance Constitutes Thinking with the Body by David Kirsh pp. 183-214 Ambiguous Coordination: Collaboration in Informal Science Education Research by Ivan Rosero, Robert Lecusay, Michael Cole pp. 215-240...

  14. External-Memory Multimaps

    CERN Document Server

    Angelino, Elaine; Mitzenmacher, Michael; Thaler, Justin

    2011-01-01

    Many data structures support dictionaries, also known as maps or associative arrays, which store and manage a set of key-value pairs. A \\emph{multimap} is generalization that allows multiple values to be associated with the same key. For example, the inverted file data structure that is used prevalently in the infrastructure supporting search engines is a type of multimap, where words are used as keys and document pointers are used as values. We study the multimap abstract data type and how it can be implemented efficiently online in external memory frameworks, with constant expected I/O performance. The key technique used to achieve our results is a combination of cuckoo hashing using buckets that hold multiple items with a multiqueue implementation to cope with varying numbers of values per key. Our external-memory results are for the standard two-level memory model.

  15. Scaling and particulate fouling in membrane filtration systems

    NARCIS (Netherlands)

    Boerlage, S.F.E.

    2001-01-01

    Membrane filtration technologies have emerged as cost competitive and viable techniques in drinking and industrial water production. Despite advancements in membrane manufacturing and technology, membrane scaling and fouling remain major problems and may limit future growth in the industry. Scaling

  16. 论有限责任公司股权对外转让--兼评新公司法第72条%On the External Equity Transfer of Limited Liability Company:Comment on the 7 2 nd Article of New Company Law

    Institute of Scientific and Technical Information of China (English)

    邓旭

    2013-01-01

    有限责任公司具有封闭性,人合性的特点,因此各国公司法对其股权向股东以外的第三人转让有严格的限制。我国新公司法对有限责任公司股权的对外转让主要是在公司法第72条中规定的,这里在对比新旧公司法关于有限责任公司股权对外转让规定的基础上,分析新公司法修改的优点和先进性,并着重对72条一些立法不足进行了研究与反思。%A limited liability company has closed,co-author nature,so in the world,every company has strict transfer restrictions to the third party beyond the company shareholders.China's New Company Law prescribes the external equity transfer of limited liability company in the 72nd article.The paper is based on the comparison between the old and the new company law in terms of the rights of a limited liability company transfer,analyzing the advantages and focusing on the legislative shortcomings.

  17. Regularization by External Variables

    DEFF Research Database (Denmark)

    Bossolini, Elena; Edwards, R.; Glendinning, P. A.

    2016-01-01

    Regularization was a big topic at the 2016 CRM Intensive Research Program on Advances in Nonsmooth Dynamics. There are many open questions concerning well known kinds of regularization (e.g., by smoothing or hysteresis). Here, we propose a framework for an alternative and important kind of regula...... of regularization, by external variables that shadow either the state or the switch of the original system. The shadow systems are derived from and inspired by various applications in electronic control, predator-prey preference, time delay, and genetic regulation....

  18. On the dielectric relaxation of biological cell suspensions: the effect of the membrane electrical conductivity.

    Science.gov (United States)

    Di Biasio, A; Cametti, C

    2011-06-01

    Due to the mismatch of the electrical parameters (the permittivity ϵ' and the electrical conductivity σ) of the membrane of a biological cell with the ones of the cytosol and the extracellular medium, biological cell suspensions are the site, under the influence of an external electric field, of large dielectric relaxations in the radiowave frequency range. However, a point still remains controversial, i.e., whether or not the value of membrane conductivity σ(s) might be extracted from the de-convolution of the dielectric spectra or otherwise if it would be more reasonable to assign to the membrane conductivity a value equal to zero. This point is not to be considered with superficiality since it concerns an a priori choice which ultimately influences the values of the electrical parameters deduced from this technique. As far as this point is concerned, the opinion of the researchers in this field diverges. We believe that, at least within certain limits, the membrane conductivity can be deduced from the shape of the relaxation spectra. We substantiate this thesis with two different examples concerning the first a suspension of human normal erythrocyte cells and the second a suspension of human lymphocyte cells. In both cases, by means of an accurate fitting procedure based on the Levenberg-Marquardt method for complex functions, we can evaluate the membrane conductivity σ(s) with its associated uncertainty. The knowledge of the membrane electrical conductivity will favor the investigation of different ion transport mechanisms across the cell membrane.

  19. 有限内固定结合铰链式超关节外固定架治疗肱骨远端复杂骨折%Limited internal fixation combined with super-articular external fixator for complex distal humeral fractures

    Institute of Scientific and Technical Information of China (English)

    郭亚洲; 徐辉; 郑均华; 万昌涛; 钱苏林; 曾舸

    2012-01-01

    Objective To evaluate the application of limited internal fixation combined with hinged super - articular external fixator for complex distal humeral fractures( CDHF ). Methods Twelve cases of CDHF were treated with limited internal fixation combined with hinged super - articular externnal fixator, and the results were analyzed. Results All 12 patients were followed up for a mean duration of 7 months( range 4 ~ 15 months ). According to the Morrey scoring system,results were excellent in 7 cases, good in 3 , fair in 2, and the effective rate was 83. 3% . All cases of fracture healed without severe complication such as infection,limited flection or extension of elbow joint,cubitus varus and nerve injury. Conclusion Limited internal fixation combined with hinged super - articular external fixator in treatment of complex distal humeral fractures can promote early rehabilitation and improve the recovery of elbow function, which is an effective treatment for CDHF.%目的 总结有限内固定结合铰链式超关节外固定架治疗肱骨远端复杂骨折的效果.方法 对12例肱骨远端复杂骨折采用有限内固定结合铰链式超关节外固定架固定进行治疗.结果 12 例全部获得随访,随访时间平均7个月(4~15个月),根据Morrey指定评估指数评价,优7例,良3例,可2例.优良率83.3%.无感染、关节僵硬、肘内翻畸形、神经损伤等严重并发症发生.结论 有限内固定结合铰链式超关节外固定架治疗能早期进行关节活动,可明显恢复关节功能,是一种良好的治疗肱骨远端复杂骨折的方法.

  20. Control of External Kink Instability

    Science.gov (United States)

    Navratil, Gerald

    2004-11-01

    A fundamental pressure and current limiting phenomenon in magnetically confined plasmas for fusion energy is the long wavelength ideal-MHD kink mode. These modes have been extensively studied in tokamak and reversed field pinch (RFP) devices. They are characterized by significant amplitude on the boundary of the confined plasma and can therefore be controlled by manipulation of the external boundary conditions. In the past ten years, the theoretically predicted stabilizing effect of a nearby conducting wall has been documented in experiments, which opens the possibility of a significant increase in maximum stable plasma pressure. While these modes are predicted to remain unstable when the stabilizing wall is resistive, their growth rates are greatly reduced from the hydrodynamic time scale to the time scale of magnetic diffusion through the resistive wall. These resistive wall slowed kink modes have been identified as limiting phenomena in tokamak (DIII-D, PBX-M, HBT-EP, JT-60U, JET, NSTX) and RFP (HBTX, Extrap, T2R) devices. The theoretical prediction of stabilization to nearly the ideal wall pressure limit by toroidal plasma rotation and/or active feedback control using coils has recently been realized experimentally. Sustained, stable operation at double the no-wall pressure limit has been achieved. Discovery of the phenomenon of resonant field amplification by marginally stable kink modes and its role in the momentum balance of rotationally stabilized plasmas has emerged as a key feature. A theoretical framework, based on an extension of the very successful treatment of the n=0 axisymmetric mode developed in the early 1990's, to understand the stabilization mechanisms and model the performance of active feedback control systems is now established. This allows design of kink control systems for burning plasma experiments like ITER.

  1. Biophysics of α-synuclein membrane interactions.

    Science.gov (United States)

    Pfefferkorn, Candace M; Jiang, Zhiping; Lee, Jennifer C

    2012-02-01

    Membrane proteins participate in nearly all cellular processes; however, because of experimental limitations, their characterization lags far behind that of soluble proteins. Peripheral membrane proteins are particularly challenging to study because of their inherent propensity to adopt multiple and/or transient conformations in solution and upon membrane association. In this review, we summarize useful biophysical techniques for the study of peripheral membrane proteins and their application in the characterization of the membrane interactions of the natively unfolded and Parkinson's disease (PD) related protein, α-synuclein (α-syn). We give particular focus to studies that have led to the current understanding of membrane-bound α-syn structure and the elucidation of specific membrane properties that affect α-syn-membrane binding. Finally, we discuss biophysical evidence supporting a key role for membranes and α-syn in PD pathogenesis. This article is part of a Special Issue entitled: Membrane protein structure and function.

  2. External-field-free magnetic biosensor

    Energy Technology Data Exchange (ETDEWEB)

    Li, Yuanpeng; Wang, Yi; Klein, Todd; Wang, Jian-Ping, E-mail: jpwang@umn.edu [Department of Electrical and Computer Engineering, University of Minnesota, Minneapolis, Minnesota 55455 (United States)

    2014-03-24

    In this paper, we report a magnetic nanoparticle (MNP) detection scheme without the presence of any external magnetic field. The proposed magnetic sensor uses a patterned groove structure within the sensor so that no external magnetic field is needed to magnetize the MNPs. An example is given based on a giant magnetoresistance (GMR) sensing device with a spin valve structure. For this structure, the detection of MNPs located inside the groove and near the free layer is demonstrated under no external magnetic field. Micromagnetic simulations are performed to calculate the signal to noise level of this detection scheme. A maximum signal to noise ratio (SNR) of 18.6 dB from one iron oxide magnetic nanoparticle with 8 nm radius is achieved. As proof of concept, this external-field-free GMR sensor with groove structure of 200 nm × 200 nm is fabricated using a photo and an electron beam integrated lithography process. Using this sensor, the feasibility demonstration of the detection SNR of 9.3 dB is achieved for 30 μl magnetic nanoparticles suspension (30 nm iron oxide particles, 1 mg/ml). This proposed external-field-free sensor structure is not limited to GMR devices and could be applicable to other magnetic biosensing devices.

  3. Light Responsive Polymer Membranes: A Review

    Directory of Open Access Journals (Sweden)

    Fiore Pasquale Nicoletta

    2012-03-01

    Full Text Available In recent years, stimuli responsive materials have gained significant attention in membrane separation processes due to their ability to change specific properties in response to small external stimuli, such as light, pH, temperature, ionic strength, pressure, magnetic field, antigen, chemical composition, and so on. In this review, we briefly report recent progresses in light-driven materials and membranes. Photo-switching mechanisms, valved-membrane fabrication and light-driven properties are examined. Advances and perspectives of light responsive polymer membranes in biotechnology, chemistry and biology areas are discussed.

  4. Modeling anisotropic elasticity of fluid membranes

    CERN Document Server

    Ramakrishnan, N; Ipsen, John H; 10.1002/mats.201100002

    2011-01-01

    The biological membrane, which compartmentalizes the cell and its organelles, exhibit wide variety of macroscopic shapes of varying morphology and topology. A systematic understanding of the relation of membrane shapes to composition, external field, environmental conditions etc. have important biological relevance. Here we review the triangulated surface model, used in the macroscopic simulation of membranes and the associated Monte Carlo (DTMC) methods. New techniques to calculate surface quantifiers, that will facilitate the study of additional in-plane orientational degrees of freedom, has been introduced. The mere presence of a polar and nematic fields in the ordered phase drives the ground state conformations of the membrane to a cylinder and tetrahedron respectively.

  5. Failure Modes of thin supported Membranes

    DEFF Research Database (Denmark)

    Hendriksen, Peter Vang; Høgsberg, J.R.; Kjeldsen, Ane Mette;

    2007-01-01

    Four different failure modes relevant to tubular supported membranes (thin dense films on a thick porous support) were analyzed. The failure modes were: 1) Structural collapse due to external pressure 2) burst of locally unsupported areas, 3) formation of surface cracks in the membrane due to TEC......-mismatches, and finally 4) delamination between membrane and support due to expansion of the membrane on use. Design criteria to minimize risk of failure by the four different modes are discussed. The theoretical analysis of the two last failure modes is compared to failures observed on actual components....

  6. 两种手术方法治疗儿童不可复性肱骨髁上骨折的疗效比较%Limited open reduction with internal fixation versus closed reduction with external fixation in the treatment of irreducible supracondylar humerus fractures in children: an outcome comparison

    Institute of Scientific and Technical Information of China (English)

    李凡; 李明静; 刘郁东; 徐剑; 胡涛

    2016-01-01

    目的 比较有限切开复位克氏针经皮内固定与闭合复位外固定支架外固定治疗儿童不可复性肱骨髁上骨折的疗效.方法 自2012年1月至2014年1月,我们共收治34例儿童不可复性Gartland Ⅲ型肱骨髁上骨折患儿,其中18例行有限切开复位克氏针经皮内固定(内固定组),16例行闭合复位外固定支架外固定(外固定组).比较两组患儿的手术时间、术中透视次数、骨折愈合时间、术后3d与2个月时Baumann角的变化及肘关节功能.结果 术后所有患儿均获得随访,时间为12~24个月,平均16.5个月.内固定组手术时间(49.1±6.6)min较外固定组(72.3±12.6)min短,术中透视次数(3.6±0.9)次较外固定组(10.1±2.0)次少,差异均有统计学意义(P<0.05).两组患儿均在术后4周获骨折临床愈合,术后2个月获骨性愈合.内固定组术后3d与2个月时Baumann角变化(2.4±1.3)°与外固定组(6.1±2.1)°比较,差异有统计学意义(P< 0.0001).按照Flynn肘关节评分标准评定疗效:术后3个月内固定组优良率为27.8%(5/18),外固定组为25.0%(4/16);术后1年内固定组优良率为99.4%(17/18)、外固定组为81.3%(13/16).两组患儿均无骨折延迟愈合、骨筋膜室综合征及医源性血管神经损伤等并发症.结论 有限切开复位克氏针经皮内固定与闭合复位外固定支架外固定治疗儿童不可复性Gartland Ⅲ型肱骨髁上骨折,骨折愈合时间相同,但前者可获得更满意的复位、更稳定的固定、更好的肘关节功能,而且手术时间短,术中透视次数少.%Objective To compare the clinical results of treating irreducible supracondylar humerus fractures (Gartland type Ⅲ) in children with limited open reduction and internal fixation versus closed reduction with external fixator.Methods The clinical data of 34 pediatric patients who had been treated for supracondylar humerus fractures (Gartland type Ⅲ) from January 2012 to January 2014 were

  7. Cholesterol, sphingolipids, and glycolipids: What do we know about their role in raft-like membranes?

    DEFF Research Database (Denmark)

    Rog, T.; Vattulainen, I.

    2014-01-01

    Lipids rafts are considered to be functional nanoscale membrane domains enriched in cholesterol and sphingolipids, characteristic in particular of the external leaflet of cell membranes. Lipids, together with membrane-associated proteins, are therefore considered to form nanoscale units...... emerged based on recent atomistic and coarse-grained molecular dynamics simulation studies on the key lipid raft components, which include cholesterol, sphingolipids, glycolipids, and the proteins interacting with these classes of lipids. The simulation results are compared to experiments when possible...... with potential specific functions. Although the understanding of the structure of rafts in living cells is quite limited, the possible functions of rafts are widely discussed in the literature, highlighting their importance in cellular functions. In this review, we discuss the understanding of rafts that has...

  8. Thermodynamic Free Energy Methods to Investigate Shape Transitions In Bilayer Membranes

    CERN Document Server

    Ramakrishnan, N; Radhakrishnan, Ravi

    2015-01-01

    The conformational free energy landscape of a system is a fundamental thermodynamic quantity of importance particularly in the study of soft matter and biological systems, in which the entropic contributions play a dominant role. While computational methods to delineate the free energy landscape are routinely used to analyze the relative stability of conformational states, to determine phase boundaries, and to compute ligand-receptor binding energies its use in problems involving the cell membrane is limited. Here, we present an overview of four different free energy methods to study morphological transitions in bilayer membranes, induced either by the action of curvature remodeling proteins or due to the application of external forces. Using a triangulated surface as a model for the cell membrane and using the framework of dynamical triangulation Monte Carlo, we have focused on the methods of Widom insertion, thermodynamic integration, Bennett acceptance scheme, and umbrella sampling and weighted histogram a...

  9. External Measures of Cognition

    Directory of Open Access Journals (Sweden)

    Osvaldo eCairo

    2011-10-01

    Full Text Available The human brain is undoubtedly the most impressive, complex and intricate organ that has evolved over time. It is also probably the least understood, and for that reason, the one that is currently attracting the most attention. In fact, the number of comparative analyses that focus on the evolution of brain size in Homo sapiens and other species has increased dramatically in recent years. In neuroscience, no other issue has generated so much interest and been the topic of so many heated debates as the difference in brain size between socially defined population groups, both its connotations and implications. For over a century, external measures of cognition have been related to intelligence. However, it is still unclear whether these measures actually correspond to cognitive abilities. In summary, this paper must be reviewed with this premise in mind.

  10. [Three cases of external auditory exostoses in a habitual sauna user].

    Science.gov (United States)

    Goto, Takashi; Tono, Tetsuya; Nakanishi, Haruka; Matsuda, Keiji; Ganaha, Akira; Suzuki, Mikio

    2013-11-01

    Exostoses are benign bony excrescences of the external auditory canal, commonly encountered in people who avidly engage in aquatic activities, hence the name "surfer's ear". Exostoses are more prevalent in cold water surfers, and additional years of surfing increase one's risk not only for developing an exostosis but also for developing more severe lesions. Exostoses remain clinically silent until they become large enough to impair the egress of epithelial debris and water from the canal, in which case there may be an associated external otitis and fluctuating hearing loss. Histologically, they demonstrate a laminated structure consistent with a periodic growth pattern. They may also cause a hearing loss by impinging upon the tympanic membrane and manubrium. Symptomatic relief is attained by surgical removal and skin grafting of the epithelially denuded areas of the bony walls of the external auditory canal. We report herein on 3 cases of exostoses which developed in patients who had a habit of taking a cold water bath after a hot sauna for more than 15 years: in spite of the limited time of exposure to cold water stimulation, alternating exposure to the hot environment of the sauna and cold water baths seemed to have acceralated the formation of the exostoses.

  11. The correlation between photosensitizers' membrane localization, membrane-residing targets, and photosensitization efficiency

    Science.gov (United States)

    Ytzhak, Shany; Bernstein, Shoshana; Loew, Leslie M.; Ehrenberg, Benjamin

    2009-06-01

    Various tetrapyrroles act as photosensitizers by efficiently generating singlet oxygen. Hydrophobic or amphiphilic photosensitizers are taken up by cells and are usually located in various cellular lipid membranes. Passive uptake by a membrane depends on biophysical properties of the membrane, such as its composition, temperature, phase, fluidity, electric potential etc., as well as on the external solution's properties. Although the intrinsic lifetime of singlet oxygen in the membrane phase is 10-30 μs, depending on lipid composition, it escapes much faster out of the membrane into the external or internal aqueous medium, where its lifetime is <3 μs. Any damage that singlet oxygen might inflict to membrane constituents, i.e. proteins or lipids, must thus occur while it is diffusing in the membrane. As a result, photosensitization efficiency depends, among others, on the location of the sensitizer in the membrane. Singlet oxygen can cause oxidative damage to two classes of targets in the membrane: lipids and proteins. Depolarization of the Nernst electric potential on cells' membranes was observed, but it is not clear whether lipid oxidation is a relevant factor leading to abolishing the resting potential of cells' membranes and to their death. We present a study of the effect of membrane lipid composition and the dissipation of the electric potential that is generated across the membrane. We find a clear correlation between the structure and unsaturation of lipids and the leakage of the membrane, which can be caused by their photosensitized oxidization. We demonstrate here that when liposomes are composed of mixtures similar to natural membranes, and photosensitization is being carried out under usual PDT conditions, photodamage to the lipids is not likely to cause enhanced permeability of ions through the membrane, which could be a mechanism that leads to cell death.

  12. Burgers' turbulence problem with linear or quadratic external potential

    DEFF Research Database (Denmark)

    Barndorff-Nielsen, Ole Eiler; Leonenko, N.N.

    2005-01-01

    We consider solutions of Burgers' equation with linear or quadratic external potential and stationary random initial conditions of Ornstein-Uhlenbeck type. We study a class of limit laws that correspond to a scale renormalization of the solutions.......We consider solutions of Burgers' equation with linear or quadratic external potential and stationary random initial conditions of Ornstein-Uhlenbeck type. We study a class of limit laws that correspond to a scale renormalization of the solutions....

  13. Novel Tripod Amphiphiles for Membrane Protein Analysis

    DEFF Research Database (Denmark)

    Chae, Pil Seok; Kruse, Andrew C; Gotfryd, Kamil

    2013-01-01

    Integral membrane proteins play central roles in controlling the flow of information and molecules across membranes. Our understanding of membrane protein structures and functions, however, is seriously limited, mainly due to difficulties in handling and analysing these proteins in aqueous solution...

  14. OCCUPATIONAL EXPOSURE TO EXTERNAL RADIATION IN SWITZERLAND.

    Science.gov (United States)

    Mayer, S; Baechler, S; Damet, J; Elmiger, R; Frei, D; Giannini, S; Leupin, A; Sarott, F; Schuh, R

    2016-09-01

    Individual monitoring for both external and internal exposures is well regulated in Switzerland. The article gives an overview on the occupational exposure to external radiation of workers based on the data collected in the Swiss national dose registry (NDR) in 2013. The NDR records the monthly doses of radiation workers since the introduction of ICRP 60 recommendations and is manifested in the Swiss ordinance since 1994. Annual dose limits for effective dose are typically exceeded once a year in Switzerland, mostly in medicine. The NDR is a useful optimisation tool to identify and characterise areas with the highest exposures. While exceeded dose limits were often related to accidental acute exposure in the past, they are now more related to continuous exposure during normal work, especially in medicine.

  15. Enlargement of the External Mobility Programme

    CERN Multimedia

    HR Department

    2008-01-01

    The External Mobility Programme was launched at the end of September 2007. Initially, the programme was aimed at staff members on limited-duration contracts having received formal notification of the termination of their employment contract at CERN, to help them towards their next employment. The programme provides a privileged, fast-track entry into the recruitment process of partner companies. Despite the short time since its inception, the programme has already delivered some encouraging and concrete results in terms of interviews granted to participating staff. The Programme has attracted considerable interest from both CERN personnel as well as from several major European companies. The CERN Management has decided to broaden the scope of the External Mobility Programme. The Programme is now open to: All staff members whose limited duration contract will end in less than one year, as well as all those with indefinite contracts. All fellows who have been employed by CE...

  16. Enlargement of the External Mobility Programme

    CERN Document Server

    HR Department

    2008-01-01

    The External Mobility Programme was launched at the end of September 2007. Initially, the programme was aimed at staff members on limited-duration contracts, having received formal notification of the termination of their employment contract at CERN, to help them towards their next employment. The programme provides a privileged, fast-track entry into the recruitment process of partner companies. Despite the short time since its inception, the programme has already delivered some encouraging and concrete results in terms of interviews granted to participating staff. The Programme has raised considerable interest from both CERN personnel as well as from several major European companies. CERN Management has decided to broaden the scope of the External Mobility Programme. The Programme is now open to: All staff members whose limited duration contract will end in less than one year, as well as all those with indefinite contracts. All fellows who have been employed by CERN fo...

  17. Comparison of clinical effects between external fixator combined with limited internal fixation and plates for treatment of intraarticular calcaneal fractures%外固定架结合有限内固定与钢板内固定治疗跟骨关节内骨折比较

    Institute of Scientific and Technical Information of China (English)

    柴雷子; 薛锋; 丁亮; 沈玉春; 赵勇

    2013-01-01

    Objective To investigate the clinical effects of the external fixator combined with the limited internal fixation for the treatment of intrarticular calcaneal fractures.Methods According to different ways of treatment of intraarticular calcaneal fractures,78 patients(86 feet) were divided into two groups:42 patients(48 feet) were treated with the external fixator combined with the limited internal fixation as group A; 36 patients (38 feet) were treated with plates as group B.Fracture healing time,recovery of the calcaneal,clinical outcomes and the rate of incision complications were compared.Results A total of 78 cases were followed up for 8~34 months (average 16.8 months).Both group A and B all had acceptable reduction in calcaneal length,height,width,Bohler angle,and Gissane angle,there was significant difference between preoperative and postoperative results(P <0.05),and there was no signicant difference in postoperative results between group A and group B(P >0.05).Based on the Maryland grading system,excellent rate was 89.6% in the group A,excellent rate was 86.8% in the group B,there were no significant difference between them(P >0.05).The rate of incision complications in the group A was lower than in the group B,there was significant difference between them (4.2% vs 21.1%,P <0.05).Conclusion External fixator combined with limited internal fixation for intraarticular calcaneal fractures is satisfactory and minimally invasive.%目的 探讨外固定架结合有限内固定治疗跟骨关节内骨折的临床疗效.方法 78例(86足)跟骨关节内骨折分为2组:A组42例(48足)采用外固定架结合有限内固定治疗;B组36例(38足)采用钢板内固定治疗.对两组骨折愈合时间、跟骨恢复情况、临床疗效、切口并发症发生率等指标进行比较.结果 78例均获得平均16.8(8~34)个月随访.两组术后跟骨的长度、宽度、高度、Bohler角及Gissane角均得到了良好的恢复,与术前比较

  18. External fixators in haemophilia.

    Science.gov (United States)

    Lee, V; Srivastava, A; PalaniKumar, C; Daniel, A J; Mathews, V; Babu, N; Chandy, M; Sundararaj, G D

    2004-01-01

    External fixators (EF) are not commonly used for patients with haemophilia. We describe the use of EF (Ilizarov, AO- uni- and bi-planar fixators and Charnley clamp) in nine patients (mean age: 19.2 years; range: 9-37) with haemophilia for the following indications - arthrodesis of infected joints, treatment of open fractures and osteoclasis. EF required an average of nine skin punctures [range: 4-17 were maintained for a period of 15 weeks (range: 8-29.5), without regular factor replacement, till bone healing was adequate and were removed with a single dose of factor infusion]. The mean preoperative factor level achieved was 85% (range: 64-102%). Much lower levels were subsequently maintained till wound healing. The average total factor consumption was 430 IU kg(-1) (range: 240-870), administered over a period of 17 days (range: 9-44). There were no major complications related to EF except in a patient who developed inhibitors. In conclusion, EF can be used safely in haemophilic patients who do not have inhibitors and does not require prolonged factor replacement.

  19. Articular external fixator and limited internal fixation for comminuted fracture of the distal humerus%超关节外固定架有限内固定治疗肱骨远端粉碎骨折疗效观察

    Institute of Scientific and Technical Information of China (English)

    马灿泽

    2012-01-01

    Objective To investigate the surgical treatment of distal humerus fractures and efficacy.Methods From February 2009 to August 2011 in 22 cases of distal humerus fractures in patients with hinge-type-articular external fixation combined with limited internal fixation.Including 16 males and 6 females; aged 26 to 55 years,mean 36 years old.According to AO classification,C1 type 2 cases,C2 in 10 cases,C3 in 10 cases.Results All patients were followed up for 6 months,the average healing time was 2.8 months,forearm rotation exceeds 100° ,elbow flexion and extension activities exceeds 90° ,and no nerve damage and postoperative infection.Based on the improved Glssebaum scoring system evaluate the efficacy of treatment was 81.8% excellent and good.Conclusion hinge-type-articular external fixation combined with limited internal fixation for distal humerus fracture efficacy of good,worthy of promotion.%目的 探讨治疗肱骨远端粉碎性骨折的手术及疗效.方法 自2009年2月至2011年8月对22例肱骨远端粉碎性骨折患者进行绞链式超关节外固定支架结合有限内固定治疗.其中男16例,女6例;年龄26~55岁,平均36岁.根据AO分型,C1型2例,C2型10例,C3型10例.结果 所有病例均随访6个月,平均骨折愈合时间为2.8个月,前臂旋转活动度超过100°,肘关节屈伸活动度超过90°,且无神经损伤及术后感染.根据改良Glssebaum评分系统评定疗效,治疗的总优良率为81.8%.结论 使用绞链式超关节外固定支架结合有限内固定治疗肱骨远端粉碎性骨折疗效较好,值得临床推广.

  20. 有限内固定结合外固定架治疗开放性不稳定胫腓骨骨折临床研究%Clinical Research on Limited Internal Fixation Combined with External Fixation for the Treatment of Opening Unstable Fracture of Tibia and Fibula

    Institute of Scientific and Technical Information of China (English)

    秦双安; 张建福

    2014-01-01

    目的:观察有限内固定结合外固定架治疗开放性不稳定胫腓骨骨折的临床疗效。方法:2002年2月至2008年10月收治开放性不稳定胫腓骨骨折30例,其中男18例,女12例;胫骨中上段骨折12例,中下段骨折10例,下段骨折8例;单纯胫骨骨折23例,合并腓骨骨折7例,均采用单侧三维多功能外固定器治疗。结果:开放伤口一期愈合25例,植皮愈合3例,转移皮瓣2例;骨折愈合时间6~12个月,平均10个月;随访时间6个月~1.5年,优良率为93.3%。结论:开放性不稳定胫腓骨骨折早期清创,良好复位,配合有限内固定及外固定架治疗,效果良好。%Objective:To observe the clinical curative effect of limited internal fixation combined with open external fixation for the treat-ment of unstable fractures of tibia and fibula. Methods:30 cases of patients with opening unstable fracture of tibia and fibula from Febru-ary 2002 to October 2008,including male 18 cases,female 12 cases;12 cases with fracture of middle and upside tibia,10 cases with middle and distal fracture,8 cases with distal fracture;23 cases with simple tibial fractures,7 cases with combined with fibula fracture, they all were treated with unilateral three-dimensional multi functional fixation device. Results:The open wound primary healing in 25 cases,skin grafting healing in 3 cases,rotation flap in 2 cases;Fracture healing time 6 to 12 months,an average of 10 months,the excel-lent and good rate was 93. 3% . Conclusion:The opening unstable fracture of tibia and fibula treated with early debridement,good reduc-tion,combined with limited internal fixation and external fixation has good effect.

  1. The importance of plasma membrane coenzyme Q in aging and stress responses.

    Science.gov (United States)

    Navas, Plácido; Villalba, José Manuel; de Cabo, Rafael

    2007-06-01

    The plasma membrane of eukaryotic cells is the limit to interact with the environment. This position implies receiving stress signals that affects its components such as phospholipids. Inserted inside these components is coenzyme Q that is a redox compound acting as antioxidant. Coenzyme Q is reduced by diverse dehydrogenase enzymes mainly NADH-cytochrome b(5) reductase and NAD(P)H:quinone reductase 1. Reduced coenzyme Q can prevent lipid peroxidation chain reaction by itself or by reducing other antioxidants such as alpha-tocopherol and ascorbate. The group formed by antioxidants and the enzymes able to reduce coenzyme Q constitutes a plasma membrane redox system that is regulated by conditions that induce oxidative stress. Growth factor removal, ethidium bromide-induced rho degrees cells, and vitamin E deficiency are some of the conditions where both coenzyme Q and its reductases are increased in the plasma membrane. This antioxidant system in the plasma membrane has been observed to participate in the healthy aging induced by calorie restriction. Furthermore, coenzyme Q regulates the release of ceramide from sphingomyelin, which is concentrated in the plasma membrane. This results from the non-competitive inhibition of the neutral sphingomyelinase by coenzyme Q particularly by its reduced form. Coenzyme Q in the plasma membrane is then the center of a complex antioxidant system preventing the accumulation of oxidative damage and regulating the externally initiated ceramide signaling pathway.

  2. Skepticism, contextualism, externalism and modality

    National Research Council Canada - National Science Library

    Ron Wilburn

    2006-01-01

    .... However, because efforts to contextualize externalism via subjunctive conditional analysis court circularity, it is only on an internalistic interpretation that contextualist strategies can even be motivated...

  3. M, Membranes, and OM

    CERN Document Server

    García, J A; Vergara, J D; Guijosa, Alberto

    2003-01-01

    We examine the extent to which the action for the membrane of M-theory (the eleven-dimensional construct which underlies and unifies all of the known string theories) simplifies in the so-called Open Membrane (OM) limit, a limit which lies at the root of the various manifestations of noncommutativity in the string context. In order for the discussion to be relatively self-contained, we start out by reviewing why the strings of ten-dimensional string theory are in fact membranes (M2-branes) living in eleven dimensions. After that, we recall the definition of OM theory, as well as the arguments showing that it is part of a larger, eleven-dimensional structure known as Galilean or Wrapped M2-brane (WM2) theory. WM2 theory is a rich theoretical construct which is interesting for several reasons, in particular because it is essentially a toy model of M-theory. We then proceed to deduce a membrane action for OM/WM2 theory, and spell out its implications for the four different types of M2-branes one can consider in ...

  4. Proteomics and the dynamic plasma membrane

    DEFF Research Database (Denmark)

    Sprenger, Richard R; Jensen, Ole Nørregaard

    2010-01-01

    plasma membrane is of particular interest, by not only serving as a barrier between the "cell interior" and the external environment, but moreover by organizing and clustering essential components to enable dynamic responses to internal and external stimuli. Defining and characterizing the dynamic plasma...... membrane proteome is crucial for understanding fundamental biological processes, disease mechanisms and for finding drug targets. Protein identification, characterization of dynamic PTMs and protein-ligand interactions, and determination of transient changes in protein expression and composition are among...... the challenges in functional proteomic studies of the plasma membrane. We review the recent progress in MS-based plasma membrane proteomics by presenting key examples from eukaryotic systems, including mammals, yeast and plants. We highlight the importance of enrichment and quantification technologies required...

  5. Impedance study of membrane dehydration and compression in proton exchange membrane fuel cells

    Energy Technology Data Exchange (ETDEWEB)

    Le Canut, Jean-Marc; Latham, Ruth; Merida, Walter; Harrington, David A. [Institute for Integrated Energy Systems, University of Victoria, Victoria, British Columbia (Canada)

    2009-07-15

    Electrochemical impedance spectroscopy (EIS) is used to measure drying and rehydration in proton exchange membrane fuel cells running under load. The hysteresis between forward and backward acquisition of polarization curves is shown to be largely due to changes in the membrane resistance. Drying tests are carried out with hydrogen and simulated reformate (hydrogen and carbon dioxide), and quasi-periodic drying and rehydration conditions are studied. The membrane hydration state is clearly linked to the high-frequency arc in the impedance spectrum, which increases in size for dry conditions indicating an increase in membrane resistance. Changes in impedance spectra as external compression is applied to the cell assembly show that EIS can separate membrane and interfacial effects, and that changes in membrane resistance dominate. Reasons for the presence of a capacitance in parallel with the membrane resistance are discussed. (author)

  6. A taxonomy of external and internal attention.

    Science.gov (United States)

    Chun, Marvin M; Golomb, Julie D; Turk-Browne, Nicholas B

    2011-01-01

    Attention is a core property of all perceptual and cognitive operations. Given limited capacity to process competing options, attentional mechanisms select, modulate, and sustain focus on information most relevant for behavior. A significant problem, however, is that attention is so ubiquitous that it is unwieldy to study. We propose a taxonomy based on the types of information that attention operates over--the targets of attention. At the broadest level, the taxonomy distinguishes between external attention and internal attention. External attention refers to the selection and modulation of sensory information. External attention selects locations in space, points in time, or modality-specific input. Such perceptual attention can also select features defined across any of these dimensions, or object representations that integrate over space, time, and modality. Internal attention refers to the selection, modulation, and maintenance of internally generated information, such as task rules, responses, long-term memory, or working memory. Working memory, in particular, lies closest to the intersection between external and internal attention. The taxonomy provides an organizing framework that recasts classic debates, raises new issues, and frames understanding of neural mechanisms.

  7. Membrane Vesicles and Lactamase in Erwinia herbicola Essam A ...

    African Journals Online (AJOL)

    yakoub@AHMED

    Many gram-negative bacteria produce external membrane vesicles (MVs) during growth. ..... The washed cells of E. herbicola 48 had a killing effect on most of bacteria tested .... Antimicrobial Agents & Chemotherapy 18 (3): 382-385. Neu HC ...

  8. ExternE transport methodology for external cost evaluation of air pollution

    DEFF Research Database (Denmark)

    Jensen, S. S.; Berkowicz, R.; Brandt, J.

    The report describes how the human exposure estimates based on NERI's human exposure modelling system (AirGIS) can improve the Danish data used for exposure factors in the ExternE Transport methodology. Initially, a brief description of the ExternE Tranport methodology is given and it is summaris...... how the methodology has been applied so far in a previous Danish study. Finally, results of a case study are reported. Exposure factors have been calculated for various urban categories in the Greater Copenhagen Area...

  9. ExternE transport methodology for external cost evaluation of air pollution (DK)

    Energy Technology Data Exchange (ETDEWEB)

    Solvang Jensen, S.; Berkowicz, R.; Brandt, J. [National Environmental Research Inst., Dept. of Atmospheric Environment (Denmark); Willumsen, E.; Kristensen, N.B. [COWI (Denmark)

    2004-07-01

    The report describes how the human exposure estimates based on NERI's human exposure modelling system (AiGIS) can improve the Danish data used for exposure factors in the ExternE Transport methodology. Inititally, a brief description of the ExternE Transport methodology is given and it is summarised how the methodology has been applied so far in a previous Danish study. Finally, results of a case study are reported. Exposure factors have been calculated for various urban categories in the Greater Copenhagen Area. (au)

  10. Multilayered Magnetic Gelatin Membrane Scaffolds

    Science.gov (United States)

    Samal, Sangram K.; Goranov, Vitaly; Dash, Mamoni; Russo, Alessandro; Shelyakova, Tatiana; Graziosi, Patrizio; Lungaro, Lisa; Riminucci, Alberto; Uhlarz, Marc; Bañobre-López, Manuel; Rivas, Jose; Herrmannsdörfer, Thomas; Rajadas, Jayakumar; De Smedt, Stefaan; Braeckmans, Kevin; Kaplan, David L.; Dediu, V. Alek

    2016-01-01

    A versatile approach for the design and fabrication of multilayer magnetic scaffolds with tunable magnetic gradients is described. Multilayer magnetic gelatin membrane scaffolds with intrinsic magnetic gradients were designed to encapsulate magnetized bioagents under an externally applied magnetic field for use in magnetic-field-assisted tissue engineering. The temperature of the individual membranes increased up to 43.7 °C under an applied oscillating magnetic field for 70 s by magnetic hyperthermia, enabling the possibility of inducing a thermal gradient inside the final 3D multilayer magnetic scaffolds. On the basis of finite element method simulations, magnetic gelatin membranes with different concentrations of magnetic nanoparticles were assembled into 3D multilayered scaffolds. A magnetic-gradient-controlled distribution of magnetically labeled stem cells was demonstrated in vitro. This magnetic biomaterial–magnetic cell strategy can be expanded to a number of different magnetic biomaterials for various tissue engineering applications. PMID:26451743

  11. External coating of colonic anastomoses

    DEFF Research Database (Denmark)

    Pommergaard, Hans-Christian; Achiam, Michael Patrick; Rosenberg, Jacob

    2012-01-01

    Colon anastomotic leakage remains both a frequent and serious complication in gastrointestinal surgery. External coating of colonic anastomoses has been proposed as a means to lower the rate of this complication. The aim of this review was to evaluate existing studies on external coating of colonic...

  12. Retrofitting Systems for External Walls

    DEFF Research Database (Denmark)

    Rose, Jørgen

    1997-01-01

    In this report, 9 different external and internal retrofitting systems are analyzed using numerical calculations. The analysis focuses on the thermal bridge effects in the different systems, and on this basis it is discussed whether internal or external retrofitting has the most advantages...

  13. Performance Targets and External Benchmarking

    DEFF Research Database (Denmark)

    Friis, Ivar; Hansen, Allan; Vámosi, Tamás S.

    Research on relative performance measures, transfer pricing, beyond budgeting initiatives, target costing, piece rates systems and value based management has for decades underlined the importance of external benchmarking in performance management. Research conceptualises external benchmarking...... the conditions upon which the market mechanism is performing within organizations. This paper aims to contribute to research by providing more insight to the conditions for the use of external benchmarking as an element in performance management in organizations. Our study explores a particular type of external...... towards the conditions for the use of the external benchmarks we provide more insights to some of the issues and challenges that are related to using this mechanism for performance management and advance competitiveness in organizations....

  14. Primordial membranes

    DEFF Research Database (Denmark)

    Hanczyc, Martin M; Monnard, Pierre-Alain

    2017-01-01

    Cellular membranes, which are self-assembled bilayer structures mainly composed of lipids, proteins and conjugated polysaccharides, are the defining feature of cell physiology. It is likely that the complexity of contemporary cells was preceded by simpler chemical systems or protocells during the...

  15. Robotic membranes

    DEFF Research Database (Denmark)

    Ramsgaard Thomsen, Mette

    2008-01-01

    , Vivisection and Strange Metabolisms, were developed at the Centre for Information Technology and Architecture (CITA) at the Royal Danish Academy of Fine Arts in Copenhagen as a means of engaging intangible digital data with tactile physical material. As robotic membranes, they are a dual examination...

  16. Characterization of organic membrane foulants in a forward osmosis membrane bioreactor treating anaerobic membrane bioreactor effluent.

    Science.gov (United States)

    Ding, Yi; Tian, Yu; Li, Zhipeng; Liu, Feng; You, Hong

    2014-09-01

    In this study, two aerobic forward osmosis (FO) membrane bioreactors (MBR) were utilized to treat the effluent of mesophilic (35°C) and atmospheric (25°C) anaerobic MBRs, respectively. The results showed that the FO membrane process could significantly improve the removal efficiencies of N and P. Meanwhile, the flux decline of the FOMBR treating effluent of mesophilic AnMBR (M-FOMBR) was higher than that treating effluent of atmospheric AnMBR (P-FOMBR). The organic membrane foulants in the two FOMBRs were analyzed to understand the membrane fouling behavior in FO processes. It was found that the slightly increased accumulation of protein-like substances into external foulants did not cause faster flux decline in P-FOMBR than that in M-FOMBR. However, the quantity of organic matter tended to deposit or adsorb into FO membrane pores in P-FOMBR was less than that in M-FOMBR, which was accordance with the tendency of membrane fouling indicated by flux decline.

  17. Current-Induced Membrane Discharge

    DEFF Research Database (Denmark)

    Andersen, Mathias Bækbo; van Soestbergen, M.; Mani, A.;

    2012-01-01

    Possible mechanisms for overlimiting current (OLC) through aqueous ion-exchange membranes (exceeding diffusion limitation) have been debated for half a century. Flows consistent with electro-osmotic instability have recently been observed in microfluidic experiments, but the existing theory...... neglects chemical effects and remains to be quantitatively tested. Here, we show that charge regulation and water self-ionization can lead to OLC by "current-induced membrane discharge'' (CIMD), even in the absence of fluid flow, in ion-exchange membranes much thicker than the local Debye screening length....... Salt depletion leads to a large electric field resulting in a local pH shift within the membrane with the effect that the membrane discharges and loses its ion selectivity. Since salt co-ions, H+ ions, and OH- ions contribute to OLC, CIMD interferes with electrodialysis (salt counterion removal...

  18. External costs related to power production technologies. ExternE national implementation for Denmark

    Energy Technology Data Exchange (ETDEWEB)

    Schleisner, L.; Sieverts Nielsen, P.

    1997-12-01

    The objective of the ExternE National Implementation project has been to establish a comprehensive and comparable set of data on externalities of power generation for all EU member states and Norway. The tasks include the application of the ExternE methodology to the most important fuel cycles for each country as well as to update the already existing results; to aggregate these site- and technology-specific results to more general figures. The current report covers the results of the national implementation for Denmark. Three different fuel cycles have been chosen as case studies. These are fuel cycles for an offshore wind farm and a wind farm on land, a decentralised CHP plant based on natural gas and a decentralised CHP plant based on biogas. The report covers all the details of the application of the methodology to these fuel cycles aggregation to a national level. (au) EU-JOULE 3. 59 tabs., 25 ills., 61 refs.

  19. Current-Induced Membrane Discharge

    OpenAIRE

    Andersen, MB; Soestbergen, van, M Michiel; A Mani; Bruus, H.; Biesheuvel, PM; Bazant, MZ

    2012-01-01

    Possible mechanisms for overlimiting current (OLC) through aqueous ion-exchange membranes (exceeding diffusion limitation) have been debated for half a century. Flows consistent with electro-osmotic instability have recently been observed in microfluidic experiments, but the existing theory neglects chemical effects and remains to be quantitatively tested. Here, we show that charge regulation and water self-ionization can lead to OLC by “current-induced membrane discharge” (CIMD), even in the...

  20. VAC® for external fixation of flail chest

    Directory of Open Access Journals (Sweden)

    Rikke Winge

    2012-06-01

    Full Text Available A large anterior chest wall defect following tumor resection was reconstructed with a Gore- Tex® membrane and a combined musculocutaneous rectus femoris and tensor fasciae latae free flap. Subsequent paradoxical respiration impeded weaning from the ventilator. Appliance of Vacuum Assisted Closure® (VAC® resulted in immediate chest wall stability and a decrease in the patient’s need for respiratory support. Shortly thereafter, the VAC® was discontinued and the patient was discharged from the intensive care unit (ICU. This case report is the first to describe the successful use of VAC® as an adjuvant to a one-stage procedure for large thoracic wall reconstruction, allowing sufficient temporary external fixation to eliminate paradoxical respiration and plausibly shorten the stay in the ICU. No adverse effects on flap healing or haemodynamics were recorded. It is likely that external VAC® can improve thoracic stability and pulmonary function in a patient with flail chest and decrease the need for mechanical ventilation.

  1. External Otitis: An Unusual Presentation in Neonates

    Directory of Open Access Journals (Sweden)

    Peymaneh Alizadeh Taheri

    2016-01-01

    Full Text Available Acute otitis externa (AOE is an infection of the external auditory canal, the auricle, and the outer surface of the tympanic membrane. Although AOE is one of the most common otologic conditions encountered in pediatric population, it is known to primarily affect children older than 2 years. We report a case of AOE caused by Staphylococcus aureus in a 23-day-old neonate. A 23-day-old female infant presented to our neonatology clinic with irritability and discharge from the right ear. There were yellow otorrhea, mild erythema, and edema of right external ear canal. There was no sign of otitis media on otoscopy. The results of laboratory tests were insignificant. The discharge culture grew colonies of methicillin-sensitive Staphylococcus aureus. After 48 hours of treatment with intravenous cloxacillin, significant improvement was observed. The present case highlights an unusual presentation of staphylococcal infection in a neonate. This is the first case of methicillin-sensitive Staphylococcus aureus otitis externa in an immunocompetent newborn.

  2. The Breakdown of String Perturbation Theory for Many External Particles

    CERN Document Server

    Ghosh, Sudip

    2016-01-01

    We consider massless string scattering amplitudes in a limit where the number of external particles becomes very large, while the energy of each particle remains small. Using the growth of the volume of the relevant moduli space, and by means of independent numerical evidence, we argue that string perturbation theory breaks down in this limit. We discuss some remarkable implications for the information paradox.

  3. Breakdown of String Perturbation Theory for Many External Particles.

    Science.gov (United States)

    Ghosh, Sudip; Raju, Suvrat

    2017-03-31

    We consider massless string scattering amplitudes in a limit where the number of external particles becomes very large, while the energy of each particle remains small. Using the growth of the volume of the relevant moduli space, and by means of independent numerical evidence, we argue that string perturbation theory breaks down in this limit. We discuss some remarkable implications for the information paradox.

  4. External fuel thermionic reactor system.

    Science.gov (United States)

    Mondt, J. F.; Peelgren, M. L.

    1971-01-01

    Thermionic reactors are prime candidates for nuclear electric propulsion. The national thermionic reactor effort is concentrated on the flashlight concept with the external-fuel concept as the backup. The external-fuel concept is very adaptable to a completely modular power subsystem which is attractive for highly reliable long-life applications. The 20- to 25-cm long, externally-fueled converters have been designed, fabricated, and successfully tested with many thermal cycles by electrical heating. However, difficulties have been encountered during encapsulation for nuclear heated tests and none have been started to date. These nuclear tests are required to demonstrate the concept feasibility.

  5. Anion permselective membrane. [For redox fuel cells

    Energy Technology Data Exchange (ETDEWEB)

    Alexander, S.S.; Hodgdon, R.B.

    1978-01-01

    Experimental anion permeselective membranes were improved and characterized for use as separators in a chemical redox, power storage cell being developed at the NASA Lewis Research Center. The goal of minimal Fe/sup +3/ ion transfer was achieved for each candidate membrane system. Minimal membrane resistivity was demonstrated by reduction of film thickness using synthetic backing materials but usefulness of thin membranes was limited by the scarcity of compatible fabrics. The most durable and useful backing fabrics were modacrylics. One membrane, a copolymer of 4 vinylpyridine and vinyl benzylchloride was outstanding in overall electrochemical and physical properties. Long term (1000 hrs) membrane chemical and thermal durability in redox environment was shown by three candidate polymers and two membranes. The remainder had good durability at ambient temperature. Manufacturing capability was demonstrated for large scale production of membrane sheets 5.5 ft/sup 2/ in area for two candidate systems.

  6. Highly stable and self-repairing membrane-mimetic 2D nanomaterials assembled from lipid-like peptoids

    Energy Technology Data Exchange (ETDEWEB)

    Jin, Haibao; Jiao, Fang; Daily, Michael D.; Chen, Yulin; Yan, Feng; Ding, Yanhuai; Zhang, Xin; Robertson, Ellen J.; Baer, Marcel D.; Chen, Chunlong

    2016-07-12

    Two-dimensional (2D) materials with molecular-scale thickness have attracted increasing interest for separation, electronic, catalytic, optical, energy and biomedical applications.1-4 Although extensive research on 2D materials, such as graphene and graphene oxide, has been performed in recent years, progress is limited on self-assembly of 2D materials from sequence-specific macromolecules,5-7 especially from synthetic sequences that could exhibit lipid-like self-assembly of bilayer sheets and mimic membrane proteins for functions. The creation of such new class of materials could enable development of highly stable biomimetic membranes that exhibit cell-membrane-like molecular transport with exceptional selectively and high transport rates.8,9 Here we demonstrate self-assembly of lipid-like 12-mer peptoids into extremely stable, crystalline, flexible and free-standing 2D membrane materials. As with cell membranes, upon exposure to external stimuli, these materials exhibit changes in thickness,10 varying from 3.5 nm to 5.6 nm. We find that self-assembly occurs through a facile crystallization process, in which inter-peptoid hydrogen bonds and enhanced hydrophobic interactions drive the formation of a highly-ordered structure. Molecular simulation confirms this is the energetically favored structure. Displaying functional groups at arbitrary locations of membrane-forming peptoids produces membranes with similar structures. This research further shows that single-layer membranes can be coated onto substrate surfaces. Moreover, membranes with mechanically-induced defects can self-repair. Given that peptoids are sequence-specific and exhibit protein-like molecular recognition with enhanced stability,11 we anticipate our membranes to be a robust platform tailored to specific applications.

  7. Combination of external loads

    Energy Technology Data Exchange (ETDEWEB)

    Frandsen, S.; Tarp Johansen, N.J.; Joergensen, H. [Forskningscenter Risoe, Roskilde (Denmark); Gravesen, H.; Soerensen, S.L. [Carl Bro, Glostrup (Denmark); Pedersen, J. [Elsam Engineering, Fredericia (Denmark); Zorn, R.; Hvidberg Knudsen, M. [DHI Water and Environment, Hoersholm (Denmark); Voelund, P. [Energi E2, Koebenhavn (Denmark)

    2003-09-01

    The project onbectives have been: To improve and consequently opimise the basis for design of offshore wind turbines. This is done through 1) mapping the wind, wave ice and current as well as correlations of these, and 2) by clarifyring how these external conditions transform into loads. A comprehensive effort has been made to get a thorough understanding of the uncertainties that govern the reliability of wind turbines with respect to wind and wave loading. One of the conclusions is that the reliability of wind turbines is generally lower, than the average reliability of building structures that are subject not only to environmental loads, which are very uncertain, but also imposed loads and self weight, which are less uncertain than the environmental loads. The implication is that, at the moment lower load partial safety factors for onshore wind turbines cannot be recommended. For the combination of wind and wave design loads the problem is twofold: 1). A very conservative design will be generated by simply adding the individual wind and wave design loads disregarding the independence of the short-term fluctuations of wind and wave loads. 2). Characteristic values and partial safety factors for wind and wave loads are not defined similarly. This implies that the reliability levels of turbine support structures subject to purely aerodynamic loads and subject to purely hydrodynamic loads are not identical. For the problem of combining aerodynamic design loads and hydrodynamic design loads two results have been obtained in the project: 1). By simple means a site specific wave load safety factor rendering the same safety level for hydrodynamic loads as for aerodynamic loads is derived, and next, by direct square summation of extreme fluctuations, the wind and wave load safety factors are weighted. 2). Under the assumptions that a deep water site is considered and that the wave loading is a fifty-fifty mix of drag and inertia the same wind and wave load safety factor

  8. Ceramic Membranes for Ammonia Recovery

    Energy Technology Data Exchange (ETDEWEB)

    Camus, O.; Perera, S.; Crittenden, B. [Department of Chemical Engineering, University of Bath, Bath, BA2 7AY (United Kingdom); Van Delft, Y.C.; Meyer, D.F.; Pex, P.P.A.C. [ECN Solar Energy, Westerduinweg 3, P.O. Box 1, 1755 ZG Petten (Netherlands); Kumakiri, I.; Miachon, S.; Dalmon, J.A. [CNRS-Institut de Recherches sur la Catalyse 2, av. A. Einstein, 69626 Villeurbanne (France); Tennison, S. [MAST Carbon, Ltd., Henley Park, Guildford, Surrey, GU3 2AF (United Kingdom); Chanaud, P. [Pall-Exekia, BP1, Usine a Bazet (France); Groensmit, E. [Kemira GrowHow SA/NV, Avenue Einstein 11, B-1300 Wavre (Belgium); Nobel, W. [Continental Engineers BV, Rustenburg 114, 1506 AZ Zaandam (Netherlands)

    2008-12-15

    An extensive screening program has been performed to find a suitable membrane configuration and operating conditions for the effective recovery of ammonia from the syngas loop. All the experiments have been performed at steady state. MFI zeolite membranes in tubular and multi-channel fiber configurations have been tested along with tubular silica membranes. At 80C, a high ammonia permeance (2.1 x 10{sup -7} mol.m{sup -2}.s{sup -1}.Pa{sup -1}), and a selectivity of about 10 were found with the tubular zeolite membrane, whereas for the silica membrane an even higher ammonia permeance was measured (7.6 x 10{sup -7} mol.m{sup -2}.s{sup -1}.Pa{sup -1}) with a selectivity of about 7. For both silica and zeolite membranes, the selectivity was found to increase with increasing temperature up to 80C. This is a combined effect of weaker adsorption of ammonia and increased diffusion at higher temperature. The results have been modeled using both the well-mixed reactor and the log mean pressure difference approaches. To overcome their limitations in addressing changes in feed concentration along the membrane surface, a segmental model has been used to obtain suitable operating conditions and membrane areas required for an industrial application.

  9. Quantum mechanics in strong time dependent external fields

    Energy Technology Data Exchange (ETDEWEB)

    Pomeau, Y.

    1986-01-01

    In quantum mechanics, time dependent Hamiltonians are most often studied by perturbation methods, the amplitude of the unsteady force being assumed to be small. On two examples (two level system with a large time dependent coupling, and atoms in large external unsteady field). I show that the opposite limit (large time dependent field) can be analyzed in some details too. For a particle in a central potential and submitted to a large periodic external field, one is led to make a Kapitza averaging because the intrinsic frequency tends to zero when the external field diverges. In that way one has to introduce a steady effective potential with singular turning points.

  10. External costs related to power production technologies. ExternE national implementation for Denmark

    Energy Technology Data Exchange (ETDEWEB)

    Schleisner, L.; Sieverts Nielsen, P. [eds.

    1997-12-01

    The objective of the ExternE National Implementation project has been to establish a comprehensive and comparable set of data on externalities of power generation for all EU member states and Norway. The tasks include the application of the ExternE methodology to the most important fuel cycles for each country as well as to update the already existing results, to aggregate these site- and technology-specific results to more general figures. The current report covers the detailed information concerning the ExternE methodology. Importance is attached to the computer system used in the project and the assessment of air pollution effects on health, materials and ecological effects. Also the assessment of global warming damages are described. Finally the report covers the detailed information concerning the national implementation for Denmark for an offshore wind farm and a wind farm on land, a decentralised CHP plant based on natural gas and a decentralised CHP plant base on biogas. (au) EU-JOULE 3. 79 tabs., 11 ills., 201 refs.

  11. Externality and burnout among dentists.

    Science.gov (United States)

    St-Yves, A; Freeston, M H; Godbout, F; Poulin, L; St-Amand, C; Verret, M

    1989-12-01

    This study investigates the relationship between burnout as measured by the Maslach Burnout Inventory and locus of control as measured by the Adult Nowicki-Strickland Internal-External Locus of Control (ANS-IE) for 82 dentists. Significant Pearson correlations between two Maslach subscales and locus of control show Personal Accomplishment to be negatively associated -.31 and Emotional Exhaustion to be positively correlated .21 to externality.

  12. Relatie interne en externe audit

    OpenAIRE

    Ghys, Emelie

    2011-01-01

    In het eerste hoofdstuk wordt de probleemstelling van deze eindverhandeling besproken. Interne en externe audit worden de laatste jaren internationaal en nationaal meer en meer erkend in het bedrijfsleven. Aanleiding voor de toenemende belangstelling van de interne en externe auditfunctie zijn de verschillende boekhoudschandalen rond corporate governance of deugdelijk bestuur. Deze financiële mislukkingen leidden wereldwijd tot diverse wetten, nieuwe regels en verbeterde standaarden om zo een...

  13. Performance Targets and External Benchmarking

    DEFF Research Database (Denmark)

    Friis, Ivar; Hansen, Allan; Vámosi, Tamás S.

    as a market mechanism that can be brought inside the firm to provide incentives for continuous improvement and the development of competitive advances. However, whereas extant research primarily has focused on the importance and effects of using external benchmarks, less attention has been directed towards...... towards the conditions for the use of the external benchmarks we provide more insights to some of the issues and challenges that are related to using this mechanism for performance management and advance competitiveness in organizations....

  14. Parallel External Memory Graph Algorithms

    DEFF Research Database (Denmark)

    Arge, Lars Allan; Goodrich, Michael T.; Sitchinava, Nodari

    2010-01-01

    In this paper, we study parallel I/O efficient graph algorithms in the Parallel External Memory (PEM) model, one o f the private-cache chip multiprocessor (CMP) models. We study the fundamental problem of list ranking which leads to efficient solutions to problems on trees, such as computing lowest...... an optimal speedup of ¿(P) in parallel I/O complexity and parallel computation time, compared to the single-processor external memory counterparts....

  15. Molecular dynamics of membrane proteins.

    Energy Technology Data Exchange (ETDEWEB)

    Woolf, Thomas B. (Johns Hopkins University School of Medicine, Baltimore, MD); Crozier, Paul Stewart; Stevens, Mark Jackson

    2004-10-01

    Understanding the dynamics of the membrane protein rhodopsin will have broad implications for other membrane proteins and cellular signaling processes. Rhodopsin (Rho) is a light activated G-protein coupled receptor (GPCR). When activated by ligands, GPCRs bind and activate G-proteins residing within the cell and begin a signaling cascade that results in the cell's response to external stimuli. More than 50% of all current drugs are targeted toward G-proteins. Rho is the prototypical member of the class A GPCR superfamily. Understanding the activation of Rho and its interaction with its Gprotein can therefore lead to a wider understanding of the mechanisms of GPCR activation and G-protein activation. Understanding the dark to light transition of Rho is fully analogous to the general ligand binding and activation problem for GPCRs. This transition is dependent on the lipid environment. The effect of lipids on membrane protein activity in general has had little attention, but evidence is beginning to show a significant role for lipids in membrane protein activity. Using the LAMMPS program and simulation methods benchmarked under the IBIG program, we perform a variety of allatom molecular dynamics simulations of membrane proteins.

  16. A macroscopic model of proton transport through the membrane-ionomer interface of a polymer electrolyte membrane fuel cell

    Science.gov (United States)

    Kumar, Milan; Edwards, Brian J.; Paddison, Stephen J.

    2013-02-01

    The membrane-ionomer interface is the critical interlink of the electrodes and catalyst to the polymer electrolyte membrane (PEM); together forming the membrane electrode assembly in current state-of-the-art PEM fuel cells. In this paper, proton conduction through the interface is investigated to understand its effect on the performance of a PEM fuel cell. The water containing domains at this interface were modeled as cylindrical pores/channels with the anionic groups (i.e., -SO3-) assumed to be fixed on the pore wall. The interactions of each species with all other species and an applied external field were examined. Molecular-based interaction potential energies were computed in a small test element of the pore and were scaled up in terms of macroscopic variables. Evolution equations of the density and momentum of the species (water molecules and hydronium ions) were derived within a framework of nonequilibrium thermodynamics. The resulting evolution equations for the species were solved analytically using an order-of-magnitude analysis to obtain an expression for the proton conductivity. Results show that the conductivity increases with increasing water content and pore radius, and strongly depends on the separation distance between the sulfonate groups and their distribution on the pore wall. It was also determined that the conductivity of two similar pores of different radii in series is limited by the pore with the smaller radius.

  17. Flow-driven cell migration under external electric fields

    Science.gov (United States)

    Li, Yizeng; Mori, Yoichiro; Sun, Sean X.

    2016-01-01

    Electric fields influence many aspects of cell physiology, including various forms of cell migration. Many cells are sensitive to electric fields, and can migrate toward a cathode or an anode, depending on the cell type. In this paper, we examine an actomyosin-independent mode of cell migration under electrical fields. Our theory considers a one-dimensional cell with water and ionic fluxes at the cell boundary. Water fluxes through the membrane are governed by the osmotic pressure difference across the cell membrane. Fluxes of cations and anions across the cell membrane are determined by the properties of the ion channels as well as the external electric field. Results show that without actin polymerization and myosin contraction, electric fields can also drive cell migration, even when the cell is not polarized. The direction of migration with respect to the electric field direction is influenced by the properties of ion channels, and are cell-type dependent. PMID:26765031

  18. Current limiters

    Energy Technology Data Exchange (ETDEWEB)

    Loescher, D.H. [Sandia National Labs., Albuquerque, NM (United States). Systems Surety Assessment Dept.; Noren, K. [Univ. of Idaho, Moscow, ID (United States). Dept. of Electrical Engineering

    1996-09-01

    The current that flows between the electrical test equipment and the nuclear explosive must be limited to safe levels during electrical tests conducted on nuclear explosives at the DOE Pantex facility. The safest way to limit the current is to use batteries that can provide only acceptably low current into a short circuit; unfortunately this is not always possible. When it is not possible, current limiters, along with other design features, are used to limit the current. Three types of current limiters, the fuse blower, the resistor limiter, and the MOSFET-pass-transistor limiters, are used extensively in Pantex test equipment. Detailed failure mode and effects analyses were conducted on these limiters. Two other types of limiters were also analyzed. It was found that there is no best type of limiter that should be used in all applications. The fuse blower has advantages when many circuits must be monitored, a low insertion voltage drop is important, and size and weight must be kept low. However, this limiter has many failure modes that can lead to the loss of over current protection. The resistor limiter is simple and inexpensive, but is normally usable only on circuits for which the nominal current is less than a few tens of milliamperes. The MOSFET limiter can be used on high current circuits, but it has a number of single point failure modes that can lead to a loss of protective action. Because bad component placement or poor wire routing can defeat any limiter, placement and routing must be designed carefully and documented thoroughly.

  19. External Costs Related to Power Production Technologies

    DEFF Research Database (Denmark)

    Ibsen, Liselotte Schleisner; Nielsen, Per Sieverts

    1997-01-01

    The European Commission has launched a major study project, ExternE, to develop a methodology to quantify externalities. A “National Implementation Phase”, was started under the Joule II programme with the purpose of implementing the ExternE methodology in all member states. The main objective...

  20. External Costs Related to Power Production Technologies

    DEFF Research Database (Denmark)

    Ibsen, Liselotte Schleisner; Nielsen, Per Sieverts

    1997-01-01

    The European Commission has launched a major study project, ExternE, to develop a methodology to quantify externalities. A “National Implementation Phase”, was started under the Joule II programme with the purpose of implementing the ExternE methodology in all member states. The main objective of...

  1. Classical Noncommutative Electrodynamics with External Source

    CERN Document Server

    Adorno, T C; Shabad, A E; Vassilevich, D V

    2011-01-01

    In a $U(1)_{\\star}$-noncommutative (NC) gauge field theory we extend the Seiberg-Witten (SW) map to include the (gauge-invariance-violating) external current and formulate - to the first order in the NC parameter - gauge-covariant classical field equations. We find solutions to these equations in the vacuum and in an external magnetic field, when the 4-current is a static electric charge of a finite size $a$, restricted from below by the elementary length. We impose extra boundary conditions, which we use to rule out all singularities, $1/r$ included, from the solutions. The selected solutions neither should nor do withstand the limiting transition $a \\rightarrow 0$. The static charge proves to be a magnetic dipole, with the magnetic moment depending on its size $a$. The external magnetic field modifies the long-range Coulomb field and some electromagnetic form-factors. We also analyze the ambiguity in the SW map and show that at least to the order studied here it is equivalent to the ambiguity of adding a ho...

  2. Choroid plexus potassium cotransport: modulation by osmotic stress and external potassium.

    Science.gov (United States)

    Keep, R F; Xiang, J

    1995-06-01

    The choroid plexuses are involved in CSF secretion and CSF K homeostasis. This study examines the potential role of K cotransport in these two processes using isolated rat lateral ventricle choroid plexuses. Bumetanide-sensitive 86Rb influx and efflux were measured to assess the response of K cotransport to changes in media osmolality and K concentration. Alterations in osmolality had no effect on K uptake (in the presence or absence of bumetanide). However, the efflux rate constant for K was 0.29 +/- 0.02, 0.44 +/- 0.04, and 0.84 +/- 0.06 min-1 in 240, 300, and 424 mOsm/kg solutions, respectively (p brain shrinkage during hyperosmotic stress if the cotransporter is present on the apical membrane. The rate of bumetanide-sensitive efflux was unaffected by changes in external [K]. However, the rate of K uptake (measured on return to normal [K] media) was reduced gradually by exposure to low [K]. It was 21 +/- 1, 19 +/- 3, 13 +/- 2, and 6 +/- 1 nmol/mg/min after 0, 10, 30, and 60-min exposure to 1 mM K. Sixty minutes of exposure to 1 mM [K] abolished the bumetanide-sensitive K uptake present in plexuses exposed continually to normal media. This modulation of K cotransport by external [K] may be important in CSF K homeostasis by limiting K loss from the CSF if CSF [K] is low.

  3. Multi-chamber electroosmosis using textile reinforced agar membranes--A promising concept for the future of hemodialysis.

    Science.gov (United States)

    Kofler, Markus; Lenninger, Margit; Mayer, Gert; Neuwirt, Hannes; Grimm, Michael; Bechtold, Thomas

    2016-01-20

    Renal replacement therapy options are limited to hemodialysis and peritoneal dialysis (70% of US patients) or renal transplantation. Diffusion processes are the main physico-chemical principle behind hemodialysis. An alternative way to achieve liquid flow through membranes bases on the electroosmotic flow which is observed as electrokinetic phenomenon in porous membranes which bear surface charges. Agar consists of the non-ionic agarose and the negatively charged agaropectine thus an electroosmotic flux is observed in analytical electrophoresis. In this study the potential electroosmosis on textile reinforced agar membranes as separation method was investigated. Using a five-chamber electrolysis cell and an agar membrane/cellulose fabric composite an intensive electroosmotic flow of 1-2 ml cm(2) h(-1) at 100 mA cell current could be observed. The movement of cations in the negatively charged agar structure led to an intensive electroosmotic flux, which also transported uncharged molecules such as urea, glucose through the membrane. Separation of uncharged low molecular weight molecules is determined by the membrane characteristic. The transport of ions (K(+), PO4(3-), creatinine) and uncharged molecules (urea, glucose) in electroosmotic separation experiments was monitored using a pH 5.5 phosphate electrolyte with the aim to assess the overall transport processes in the electrochemical cell. The results demonstrate the potential of the method for filtration of biological fluids in the absence of external pressure or high shear rates.

  4. Limited Neutrality

    DEFF Research Database (Denmark)

    Nielsen, Morten Ebbe Juul

    2006-01-01

    Article Concerning the prospect of a kind of limited neutrality in place of the standard liberal egalitarian "neutrality of justification."......Article Concerning the prospect of a kind of limited neutrality in place of the standard liberal egalitarian "neutrality of justification."...

  5. Limiting Skepticism

    DEFF Research Database (Denmark)

    Hendricks, Vincent Fella; Symons, John

    2011-01-01

    Skeptics argue that the acquisition of knowledge is impossible given the standing possibility of error. We present the limiting convergence strategy for responding to skepticism and discuss the relationship between conceivable error and an agent’s knowledge in the limit. We argue that the skeptic...

  6. Limited Neutrality

    DEFF Research Database (Denmark)

    Nielsen, Morten Ebbe Juul

    2006-01-01

    Article Concerning the prospect of a kind of limited neutrality in place of the standard liberal egalitarian "neutrality of justification."......Article Concerning the prospect of a kind of limited neutrality in place of the standard liberal egalitarian "neutrality of justification."...

  7. Leveraging External Sources of Innovation

    DEFF Research Database (Denmark)

    West, Joel; Bogers, Marcel

    2014-01-01

    This paper reviews research on open innovation that considers how and why firms commercialize external sources of innovations. It examines both the “outside-in” and “coupled” modes of open innovation. From an analysis of prior research on how firms leverage external sources of innovation...... cited work beyond those journals. A review of 291 open innovation-related publications from these sources shows that the majority of these articles indeed address elements of this inbound open innovation process model. Specifically, it finds that researchers have front-loaded their examination...... external innovations create value rather than how firms capture value from those innovations. Finally, the interaction phase considers both feedback for the linear process and reciprocal innovation processes such as cocreation, network collaboration, and community innovation. This review and synthesis...

  8. Coupled external cavity photonic crystal enhanced fluorescence.

    Science.gov (United States)

    Pokhriyal, Anusha; Lu, Meng; Ge, Chun; Cunningham, Brian T

    2014-05-01

    We report a fundamentally new approach to enhance fluorescence in which surface adsorbed fluorophore-tagged biomolecules are excited on a photonic crystal surface that functions as a narrow bandwidth and tunable mirror of an external cavity laser. This scheme leads to ∼10× increase in the electromagnetic enhancement factor compared to ordinary photonic crystal enhanced fluorescence. In our experiments, the cavity automatically tunes its lasing wavelength to the resonance wavelength of the photonic crystal, ensuring optimal on-resonance coupling even in the presence of variable device parameters and variations in the density of surface-adsorbed capture molecules. We achieve ∼10(5) × improvement in the limit of detection of a fluorophore-tagged protein compared to its detection on an unpatterned glass substrate. The enhanced fluorescence signal and easy optical alignment make cavity-coupled photonic crystals a viable approach for further reducing detection limits of optically-excited light emitters that are used in biological assays.

  9. Containment atmosphere response to external sprays

    Energy Technology Data Exchange (ETDEWEB)

    Green, J.; Almenas, K. [Univ. of Maryland, College Park, MD (United States)

    1995-09-01

    The application of external sprays to a containment steel shell can be an effective energy removal method and has been proposed in the passive AP-600 design. Reduction of the steel shell temperature in contact with the containment atmosphere enhances both heat and mass transfer driving forces. Large scale experimental data in this area is scarce, therefore the measurements obtained from the E series tests conducted at the German HDR facility deserve special attention. These long term tests simulated various severe accident conditions, including external spraying of the hemispherical steel shell. This investigation focuses upon the integral response of the HDR containment atmosphere during spray periods and upon methods by which lumped parameter system codes, like CONTAIN, model the underlying condensation phenomena. Increases in spray water flowrates above a minimum value were ineffective at improving containment pressure reduction since the limiting resistance for energy transfer lies in the noncondensable-vapor boundary layer at the inner condensing surface. The spray created an unstable condition by cooling the upper layers of a heated atmosphere and thus inducing global natural circulation flows in the facility and subsequently, abrupt changes in lighter-than-air noncondensable (J{sub 2}/He) concentrations. Modeling results using the CONTAIN code are outlined and code limitations are delineated.

  10. Hydrogen Selective Exfoliated Zeolite Membranes

    Energy Technology Data Exchange (ETDEWEB)

    Tsapatsis, Michael [Univ. of Minnesota, Minneapolis, MN (United States). Department of Chemical Engineering and Materials Science; Daoutidis, Prodromos [Univ. of Minnesota, Minneapolis, MN (United States). Department of Chemical Engineering and Materials Science; Elyassi, Bahman [Univ. of Minnesota, Minneapolis, MN (United States). Department of Chemical Engineering and Materials Science; Lima, Fernando [Univ. of Minnesota, Minneapolis, MN (United States). Department of Chemical Engineering and Materials Science; Iyer, Aparna [Univ. of Minnesota, Minneapolis, MN (United States). Department of Chemical Engineering and Materials Science; Agrawal, Kumar [Univ. of Minnesota, Minneapolis, MN (United States). Department of Chemical Engineering and Materials Science; Sabnis, Sanket [Univ. of Minnesota, Minneapolis, MN (United States). Department of Chemical Engineering and Materials Science

    2015-04-06

    The objective of this project was to develop and evaluate an innovative membrane technology at process conditions that would be representative of Integrated Gasification Combined Cycle (IGCC) advanced power generation with pre-combustion capture of carbon dioxide (CO2). This research focused on hydrogen (H2)-selective zeolite membranes that could be utilized to separate conditioned syngas into H2-rich and CO2-rich components. Both experiments and process design and optimization calculations were performed to evaluate the concept of ultra-thin membranes made from zeolites nanosheets. In this work, efforts in the laboratory were made to tackle two fundamental challenges in application of zeolite membranes in harsh industrial environments, namely, membrane thickness and membrane stability. Conventional zeolite membranes have thicknesses in the micron range, limiting their performance. In this research, we developed a method for fabrication of ultimately thin zeolite membranes based on zeolite nanosheets. A range of layered zeolites (MWW, RWR, NSI structure types) suitable for hydrogen separation was successfully exfoliated to their constituent nanosheets. Further, membranes were made from one of these zeolites, MWW, to demonstrate the potential of this group of materials. Moreover, long-term steam stability of these zeolites (up to 6 months) was investigated in high concentrations of steam (35 mol% and 95 mole%), high pressure (10 barg), and high temperatures (350 °C and 600 °C) relevant to conditions of water-gas-shift and steam methane reforming reactions. It was found that certain nanosheets are stable, and that stability depends on the concentration of structural defects. Additionally, models that represent a water-gas-shift (WGS) membrane reactor equipped with the zeolite membrane were developed for systems studies. These studies had the aim of analyzing the effect of the membrane reactor integration into IGCC plants

  11. The limits of filopodium stability

    CERN Document Server

    Pronk, Sander; Fletcher, Daniel A

    2008-01-01

    Filopodia are long, finger-like membrane tubes supported by cytoskeletal filaments. Their shape is determined by the stiffness of the actin filament bundles found inside them and by the interplay between the surface tension and bending rigidity of the membrane. Although one might expect the Euler buckling instability to limit the length of filopodia, we show through simple energetic considerations that this is in general not the case. By further analyzing the statics of filaments inside membrane tubes, and through computer simulations that capture membrane and filament fluctuations, we show under which conditions filopodia of arbitrary lengths are stable. We discuss several in vitro experiments where this kind of stability has already been observed. Furthermore, we predict that the filaments in long, stable filopodia adopt a helical shape.

  12. Inverse Limits

    CERN Document Server

    Ingram, WT

    2012-01-01

    Inverse limits provide a powerful tool for constructing complicated spaces from simple ones. They also turn the study of a dynamical system consisting of a space and a self-map into a study of a (likely more complicated) space and a self-homeomorphism. In four chapters along with an appendix containing background material the authors develop the theory of inverse limits. The book begins with an introduction through inverse limits on [0,1] before moving to a general treatment of the subject. Special topics in continuum theory complete the book. Although it is not a book on dynamics, the influen

  13. Current-induced membrane discharge

    CERN Document Server

    Andersen, M B; Mani, A; Bruus, H; Biesheuvel, P M; Bazant, M Z

    2012-01-01

    Possible mechanisms for over-limiting current (OLC) through aqueous ion-exchange membranes (exceeding diffusion limitation) have been debated for half a century. Flows consistent with electro-osmotic instability (EOI) have recently been observed in microfluidic experiments, but the existing theory neglects chemical effects and remains to be quantitatively tested. Here, we show that charge regulation and water self-ionization can lead to OLC by "current-induced membrane discharge" (CIMD), even in the absence of fluid flow. Salt depletion leads to a large electric field which expels water co-ions, causing the membrane to discharge and lose its selectivity. Since salt co-ions and water ions contribute to OLC, CIMD interferes with electrodialysis (salt counter-ion removal) but could be exploited for current-assisted ion exchange and pH control. CIMD also suppresses the extended space charge that leads to EOI, so it should be reconsidered in both models and experiments on OLC.

  14. Nanoengineered membranes for controlled transport

    Science.gov (United States)

    Doktycz, Mitchel J [Oak Ridge, TN; Simpson, Michael L [Knoxville, TN; McKnight, Timothy E [Greenback, TN; Melechko, Anatoli V [Oak Ridge, TN; Lowndes, Douglas H [Knoxville, TN; Guillorn, Michael A [Knoxville, TN; Merkulov, Vladimir I [Oak Ridge, TN

    2010-01-05

    A nanoengineered membrane for controlling material transport (e.g., molecular transport) is disclosed. The membrane includes a substrate, a cover definining a material transport channel between the substrate and the cover, and a plurality of fibers positioned in the channel and connected to an extending away from a surface of the substrate. The fibers are aligned perpendicular to the surface of the substrate, and have a width of 100 nanometers or less. The diffusion limits for material transport are controlled by the separation of the fibers. In one embodiment, chemical derivitization of carbon fibers may be undertaken to further affect the diffusion limits or affect selective permeability or facilitated transport. For example, a coating can be applied to at least a portion of the fibers. In another embodiment, individually addressable carbon nanofibers can be integrated with the membrane to provide an electrical driving force for material transport.

  15. Multilayer Membranes Based on Ceramic Materials—Sol-gel Synthesis, Characterization and Membrane Performance

    Institute of Scientific and Technical Information of China (English)

    Sun Qianyao; Xu Chunming

    2007-01-01

    In nearly all chemical and petrochemical systems, separation of products generally accounts for more than 50% of the capital cost and the greatest part of the energy consumption. It is generally believed that membrane systems can offer benefits in both reducing the energy consumption of the separation stages and lowering the capital expenditure (CAPEX). Microporous ceramic membranes have the potential to overcome the limitation in polymer membranes operation, which has been the subject of a large amount of research worldwide in the last two decades. And most of the research has aimed at the production of the asymmetric multilayered membrane based on amorphous oxides by sol-gel techniques. The paper is to give an overview of publications on ceramic membranes, including less common materials of titania, zirconia, which can be used for pervaporation in corrosive media. Commercially available microporous membranes based on these membrane materials and the membrane economics are also summarized.

  16. External trabeculectomy with T-Flux implant.

    LENUS (Irish Health Repository)

    Jungkim, S

    2012-02-03

    PURPOSE: To evaluate the efficacy and safety of T-Flux implant in nonpenetrating glaucoma surgery. METHODS: This clinical interventional case series study included 35 eyes of 35 patients with medically uncontrolled primary open angle glaucoma. External trabeculectomy with T-Flux (ETTF) is a technique of nonpenetrating glaucoma surgery, in which after removing deep scleral tissue and un-roofing the canal of Schlemn (CS) the external trabecular tissue is peeled off to enhance the aqueous drainage without opening the anterior chamber. A non-absorbable T-Flux implant (IOL TECH Laboratories, France) was sutured in deep intrascleral space to keep it patent. Snellen\\'s best-corrected visual acuity, slit lamp biomicroscopy, intraocular pressure (IOP), gonioscopy, funduscopy, and optic disc assessment were performed preoperatively and postoperatively at 1 day, 1 week, and 1, 3 , 6, and 12 months. Visual field testing was performed preoperatively and at 6 and 12 months postoperatively. RESULTS: For three eyes, surgery was converted to standard trabeculectomy owing to the perforation of trabeculo-Descemet\\'s membrane and iris prolapse and excluded from the study. The results of the remaining 32 eyes were included in the study. Preoperative IOP (mean +\\/- SD) of 32.88 +\\/- 5.7 mmHg decreased to 15.44 +\\/- 1.6 mmHg after 12 months. Ten eyes (28.6%) had microhyphema that resolved spontaneously; 3 eyes (8.6%) had microperforation without iris prolapse so ETTF was proceeded routinely. The preoperative number of antiglaucoma medications per patient reduced from (mean +\\/- SD) 2.74 +\\/- 0.61 to 0.11 +\\/- 0.32 postoperatively at 12 months. Visual acuity and visual fields remained stable. CONCLUSIONS: ETTF appears to provide significant control of IOP and have low incidence of complications.

  17. Composite capillary membrane for solvent resistant nanofiltration

    NARCIS (Netherlands)

    Dutczak, S.M.; Luiten-Olieman, Maria W.J.; Zwijnenberg, Harmen Jan; Bolhuis-Versteeg, Lydia A.M.; Winnubst, Aloysius J.A.; Hempenius, Mark A.; Benes, Nieck Edwin; Wessling, Matthias; Stamatialis, Dimitrios

    2011-01-01

    Solvent resistant nanofiltration (SRNF) is a membrane separation process allowing for an efficient separation of small molecules of 200–1000 g mol−1 from organic solvents. The application of SRNF in industry applications is currently hindered by a limited choice of SRNF membranes and configurations.

  18. Optimal Auctions with Financial Externalities

    NARCIS (Netherlands)

    Maasland, E.; Onderstal, A.M.

    2002-01-01

    We construct optimal auctions when bidders face financial externalities.In a Coasean World, in which the seller cannot prevent a perfect resale market, nor withhold the object, the lowest-price all-pay auction is optimal.In a Myersonean World, in which the seller can both prevent resale after the au

  19. Organizing for External Knowledge Sourcing

    DEFF Research Database (Denmark)

    Rabbiosi, Larissa; Reichstein, Toke

    2011-01-01

    The aim of this article is to provide an introduction to the special issue. We briefly consider the external knowledge sourcing and organizing for innovation literatures, which offer a background for the special issue, and we highlight their mutual dialogue. We then illustrate the main findings...

  20. Measuring Externalities in Program Evaluation

    NARCIS (Netherlands)

    Janssens, Wendy

    2005-01-01

    Impact evaluations of development programmes usually focus on a comparison of participants with a control group. However, if the programme generates externalities for non-participants such an approach will capture only part of the programme's impact. Based on a unique large-scale quantitative survey

  1. Lupus vulgaris of external nose.

    Science.gov (United States)

    Bhandary, Satheesh Kumar; Ranganna, B Usha

    2008-12-01

    Lupus vulgaris is the commonest form of cutaneous tuberculosis which commonly involve trunk and buttocks. Lupus vulgaris affecting nose and face, are rarely reported in India. This study reports an unusual case of lupus vulgaris involving the external nose that showed dramatic outcome after six months of anti- tubercular treatment.

  2. [Treatment by external insulin pump].

    Science.gov (United States)

    Clavel, Sylvaine

    2010-12-01

    Since the recent recommendations by the French speaking association for research on diabetes and metabolic illnesses (Alfediam), treatment by insulin pump has found itself in competition with basal-bolus, a procedure using similar injections of insulin which has become a benchmark treatment. The latest Alfediam guidelines focus on defining ways of treating diabetics with an external insulin pump.

  3. Matchings with Externalities and Attitudes

    DEFF Research Database (Denmark)

    Branzei, Simina; Michalak, Tomasz; Rahwan, Talal;

    2013-01-01

    Two-sided matchings are an important theoretical tool used to model markets and social interactions. In many real-life problems the utility of an agent is influenced not only by their own choices, but also by the choices that other agents make. Such an influence is called an externality. Whereas ...

  4. Post-external dacryocystorhinostomy lagophthalmos.

    Science.gov (United States)

    Odat, Thabit A; Odat, Haitham A; Khraisat, Heba; Odat, Mohannad A; Alzoubi, Firas Q

    2015-06-01

    To describe lagophthalmos and eyelid closure abnormality after external dacryocystorhinostomy (DCR). A retrospective review of medical records and postoperative photographs of 79 patients who underwent external DCR for nasolacrimal duct obstruction and developed eyelid closure abnormality and lagophthalmos with or without exposure keratopathy was conducted. Collected data included age, sex, indication for surgery, laterality, length and type of incision, length of follow-up duration, presence of punctate epithelial keratopathy, and time for resolution of eyelid closure abnormalities. Twenty-seven patients with 28 external dacryocystorhinostomy had postoperative eyelid closure abnormalities. Male to female ratio was 1:6. The mean age was 40.1 years (range 9-80 years). All surgeries were performed through diagonal skin incision. Lagophthalmos involving the medial third of the palpebral fissure was noticed in 28.6 % of cases. All patients had hypometric blink mainly of the upper eyelid. One patient had punctate epithelial keratopathy. Resolution of lagophthalmos was noticed over a period of 1-5 weeks with an average of 3 weeks. None of the patients continued to have residual hypometric blink or punctate keratopathy at the last follow-up time. The mean follow-up period was 4.2 months (range 3-6 months). Eyelid closure abnormality and lagophthalmos after external DCR are underestimated problems. Spontaneous resolution is seen in all cases weeks to months after surgery.

  5. Femoral Reconstruction Using External Fixation

    Directory of Open Access Journals (Sweden)

    Yevgeniy Palatnik

    2011-01-01

    Full Text Available Background. The use of an external fixator for the purpose of distraction osteogenesis has been applied to a wide range of orthopedic problems caused by such diverse etiologies as congenital disease, metabolic conditions, infections, traumatic injuries, and congenital short stature. The purpose of this study was to analyze our experience of utilizing this method in patients undergoing a variety of orthopedic procedures of the femur. Methods. We retrospectively reviewed our experience of using external fixation for femoral reconstruction. Three subgroups were defined based on the primary reconstruction goal lengthening, deformity correction, and repair of nonunion/bone defect. Factors such as leg length discrepancy (LLD, limb alignment, and external fixation time and complications were evaluated for the entire group and the 3 subgroups. Results. There was substantial improvement in the overall LLD, femoral length discrepancy, and limb alignment as measured by mechanical axis deviation (MAD and lateral distal femoral angle (LDFA for the entire group as well as the subgroups. Conclusions. The Ilizarov external fixator allows for decreased surgical exposure and preservation of blood supply to bone, avoidance of bone grafting and internal fixation, and simultaneous lengthening and deformity correction, making it a very useful technique for femoral reconstruction.

  6. Estimating Externalities of Natural Gas Fuel Cycles, Report 4

    Energy Technology Data Exchange (ETDEWEB)

    Barnthouse, L.W.; Cada, G.F.; Cheng, M.-D.; Easterly, C.E.; Kroodsma, R.L.; Lee, R.; Shriner, D.S.; Tolbert, V.R.; Turner, R.S.

    1998-01-01

    This report describes methods for estimating the external costs (and possibly benefits) to human health and the environment that result from natural gas fuel cycles. Although the concept of externalities is far from simple or precise, it generally refers to effects on individuals' well being, that result from a production or market activity in which the individuals do not participate, or are not fully compensated. In the past two years, the methodological approach that this report describes has quickly become a worldwide standard for estimating externalities of fuel cycles. The approach is generally applicable to any fuel cycle in which a resource, such as coal, hydro, or biomass, is used to generate electric power. This particular report focuses on the production activities, pollution, and impacts when natural gas is used to generate electric power. In the 1990s, natural gas technologies have become, in many countries, the least expensive to build and operate. The scope of this report is on how to estimate the value of externalities--where value is defined as individuals' willingness to pay for beneficial effects, or to avoid undesirable ones. This report is about the methodologies to estimate these externalities, not about how to internalize them through regulations or other public policies. Notwithstanding this limit in scope, consideration of externalities can not be done without considering regulatory, insurance, and other considerations because these institutional factors affect whether costs (and benefits) are in fact external, or whether they are already somehow internalized within the electric power market. Although this report considers such factors to some extent, much analysis yet remains to assess the extent to which estimated costs are indeed external. This report is one of a series of reports on estimating the externalities of fuel cycles. The other reports are on the coal, oil, biomass, hydro, and nuclear fuel cycles, and on general

  7. From biological membranes to biomimetic model membranes

    Directory of Open Access Journals (Sweden)

    Eeman, M.

    2010-01-01

    Full Text Available Biological membranes play an essential role in the cellular protection as well as in the control and the transport of nutrients. Many mechanisms such as molecular recognition, enzymatic catalysis, cellular adhesion and membrane fusion take place into the biological membranes. In 1972, Singer et al. provided a membrane model, called fluid mosaic model, in which each leaflet of the bilayer is formed by a homogeneous environment of lipids in a fluid state including globular assembling of proteins and glycoproteins. Since its conception in 1972, many developments were brought to this model in terms of composition and molecular organization. The main development of the fluid mosaic model was made by Simons et al. (1997 and Brown et al. (1997 who suggested that membrane lipids are organized into lateral microdomains (or lipid rafts with a specific composition and a molecular dynamic that are different to the composition and the dynamic of the surrounding liquid crystalline phase. The discovery of a phase separation in the plane of the membrane has induced an explosion in the research efforts related to the biology of cell membranes but also in the development of new technologies for the study of these biological systems. Due to the high complexity of biological membranes and in order to investigate the biological processes that occur on the membrane surface or within the membrane lipid bilayer, a large number of studies are performed using biomimicking model membranes. This paper aims at revisiting the fundamental properties of biological membranes in terms of membrane composition, membrane dynamic and molecular organization, as well as at describing the most common biomimicking models that are frequently used for investigating biological processes such as membrane fusion, membrane trafficking, pore formation as well as membrane interactions at a molecular level.

  8. Microporous Inorganic Membranes as Proton Exchange Membranes

    Energy Technology Data Exchange (ETDEWEB)

    Vichi, F.M. Tejedor-Tejedor, M.I. Anderson, Marc A

    2002-08-28

    Porous oxide electrolyte membranes provide an alternative approach to fabricating proton exchange membrane fuel cells based on inorganic materials. This study focused on elucidating the properties of these inorganic membranes that make them good electrolyte materials in membrane electrode assemblies; in particular, we investigated several properties that affect the nature of proton conductivity in these membranes. This report discusses our findings on the effect of variables such as site density, amount of surface protonation and surface modification on the proton conductivity of membranes with a fixed pore structure under selected conditions. Proton conductivities of these inorganic membranes are similar to conductivities of nafion, the polymeric membrane most commonly used in low temperature fuel cells.

  9. Defensive externality and blame projection following failure.

    Science.gov (United States)

    Hochreich, D J

    1975-09-01

    This study focuses upon the relationship between internal-external control and defensive blame projection. Trust was used as a moderator variable for making differential predictions concerning the behavior of two subgroups of externals: defensive externals, whose externality is presumed to reflect primarily a verbal technique of defense, and congruent externals, whose externality reflects a more genuine belief that most outcomes are determined by forces beyond their personal control. As predicted, defensive externals showed a stronger tendency than did congruent externals and internals to resort to blame projection following failure at an achievement task. There were no group differences in attribution following task success. Defensive externals were found to be more responsive to negative feedback than were congruent externals.

  10. The model of stress distribution in polymer electrolyte membrane

    CERN Document Server

    Atrazhev, Vadim V; Dmitriev, Dmitry V; Erikhman, Nikolay S; Sultanov, Vadim I; Patterson, Timothy; Burlatsky, Sergei F

    2014-01-01

    An analytical model of mechanical stress in a polymer electrolyte membrane (PEM) of a hydrogen/air fuel cell with porous Water Transfer Plates (WTP) is developed in this work. The model considers a mechanical stress in the membrane is a result of the cell load cycling under constant oxygen utilization. The load cycling causes the cycling of the inlet gas flow rate, which results in the membrane hydration/dehydration close to the gas inlet. Hydration/dehydration of the membrane leads to membrane swelling/shrinking, which causes mechanical stress in the constrained membrane. Mechanical stress results in through-plane crack formation. Thereby, the mechanical stress in the membrane causes mechanical failure of the membrane, limiting fuel cell lifetime. The model predicts the stress in the membrane as a function of the cell geometry, membrane material properties and operation conditions. The model was applied for stress calculation in GORE-SELECT.

  11. Performance evaluation of organic emulsion liquid membrane on phenol removal

    CERN Document Server

    Ng, Y S; Hashim, M A

    2014-01-01

    The percentage removal of phenol from aqueous solution by emulsion liquid membrane and emulsion leakage was investigated experimentally for various parameters such as membrane:internal phase ratio, membrane:external phase ratio, emulsification speed, emulsification time, carrier concentration, surfactant concentration and internal agent concentration. These parameters strongly influence the percentage removal of phenol and emulsion leakage. Under optimum membrane properties, the percentage removal of phenol was as high as 98.33%, with emulsion leakage of 1.25%. It was also found that the necessity of carrier for enhancing phenol removal was strongly dependent on the internal agent concentration.

  12. Negative Effects of Sludge Bulking in Membrane Bio-Reactor

    Institute of Scientific and Technical Information of China (English)

    ZHANG Ying; HUANG Zhi; REN Nanqi; MENG Qingjuan

    2006-01-01

    Sludge bulking property of membrane bio-reactor was investigated in this study through contrast research. When the sludge bulking appeared, the removal efficiency of COD in membrane bio-reactor increased slightly through the function of filamentous bacteria. However, the negative effects of the higher net water-head differential pressures, the high block rate of membrane pore and the great quantity of filamentous bacteria at the external surface presented at the same time. Thus, plenty of methods should be performed to control sludge bulking once it happened in membrane bio-reactor.

  13. Anaerobic membrane bioreactors: Are membranes really necessary?

    NARCIS (Netherlands)

    Davila, M.; Kassab, G.; Klapwijk, A.; Lier, van J.B.

    2008-01-01

    Membranes themselves represent a significant cost for the full scale application of anaerobic membrane bioreactors (AnMBR). The possibility of operating an AnMBR with a self-forming dynamic membrane generated by the substances present in the reactor liquor would translate into an important saving. A

  14. Microwave parametric amplifiers using externally pumped Josephson junctions

    DEFF Research Database (Denmark)

    Sørensen, O. H.; Mygind, Jesper; Pedersen, Niels Falsig

    1978-01-01

    Externally pumped parametric amplifiers are discussed. Theory and experiments on the singly degenerate parametric amplifier based on a Josephson junction are presented. Advantages and limitations of the singly degenerate and doubly degenerate parametric amplifiers are discussed. Some plans and pr...... and proposals for future research are presented....

  15. Model cell membranes

    DEFF Research Database (Denmark)

    Günther-Pomorski, Thomas; Nylander, Tommy; Cardenas Gomez, Marite

    2014-01-01

    The high complexity of biological membranes has motivated the development and application of a wide range of model membrane systems to study biochemical and biophysical aspects of membranes in situ under well defined conditions. The aim is to provide fundamental understanding of processes...... controlled by membrane structure, permeability and curvature as well as membrane proteins by using a wide range of biochemical, biophysical and microscopic techniques. This review gives an overview of some currently used model biomembrane systems. We will also discuss some key membrane protein properties...... that are relevant for protein-membrane interactions in terms of protein structure and how it is affected by membrane composition, phase behavior and curvature....

  16. Bandgap engineering of rippled MoS2 monolayer under external electric field

    Science.gov (United States)

    Qi, Jingshan; Li, Xiao; Qian, Xiaofeng; Feng, Ji

    2013-04-01

    In this letter we propose a universal strategy combining external electric field with the ripple of membrane to tune the bandgap of semiconducting atomic monolayer. By first-principles calculations we show that the bandgap of rippled MoS2 monolayer can be tuned in a large range by vertical external electric field, which is expected to have little effect on MoS2 monolayer. This phenomenon can be explained from charge redistribution under external electric field by a simple model. This may open an avenue of optimizing monolayer MoS2 for electronic and optoelectronic applications by surface patterning.

  17. External auditory canal stenosis due to the use of powdered boric acid.

    Science.gov (United States)

    Dündar, Riza; Soy, Fatih Kemal; Kulduk, Erkan; Muluk, Nuray Bayar; Cingi, Cemal

    2014-09-01

    Acquired stenosis of the external auditory canal (EAC) may occur because of chronic external otitis, recurrent chronic catarrhal otitis media associated with tympanic membrane perforation, chronic dermatitis, tumors, and trauma. Stenosis occurs generally at the one-third bone part of the external auditory canal. In this article, we present 3 cases of acquired EAC stenosis due to the previous powdered boric acid application. Besides the presentation of surgical intervetions in these cases, we want to notify the physicians not to use or carefully use powdered boric acid because of the complication of EAC stenosis.

  18. Effects of Potassium Currents upon Action Potential of Cardiac Cells Exposed to External Electric fields

    Institute of Scientific and Technical Information of China (English)

    An-Ying Zhang; Xiao-Feng Pang

    2008-01-01

    Previous studies show that exposure to high-voltage electric fields would influence the electro cardiogram both in experimental animate and human beings. The effects of the external electric fields upon action potential of cardiac cells are studied in this paper based on the dynamical model, LR91. Fourth order Runger-Kuta is used to analyze the change of potassium ion channels exposed to external electric fields in detail. Results indicate that external electric fields could influence the current of potassium ion by adding an induced component voltage on membrane. This phenomenon might be one of the reasons of heart rate anomaly under the high-voltage electric fields.

  19. Dipolar fluids under external perturbations

    Energy Technology Data Exchange (ETDEWEB)

    Klapp, Sabine H L [Stranski-Laboratorium fuer Physikalische und Theoretische Chemie Sekretariat TC7, Technische Universitaet Berlin, Strasse des 17. Juni 124, D-10623 Berlin (Germany)

    2005-04-20

    We discuss recent developments and present new findings on the structural and phase properties of dipolar model fluids influenced by various external perturbations. We concentrate on systems of spherical particles with permanent (point) dipole moments. Starting from what is known about the three-dimensional systems, particular emphasis is given to dipolar fluids in different confining situations involving both simple and complex (disordered) pore geometries. Further topics concern the effect of quenched positional disorder, the influence of external (electric or magnetic) fields, and the fluid-fluid phase behaviour of various dipolar mixtures. It is demonstrated that due to the translational-orientational coupling and due to the long range of dipolar interactions even simple perturbations such as hard walls can have a profound impact on the systems. (topical review)

  20. External observer reflections on QBism

    CERN Document Server

    Khrennikov, Andrei

    2015-01-01

    In this short review I present my personal reflections on QBism. I have no intrinsic sympathy neither to QBism nor to subjective interpretation of probability in general. However, I have been following development of QBism from its very beginning, observing its evolution and success, sometimes with big surprise. Therefore my reflections on QBism can be treated as "external observer" reflections. I hope that my representation of this interpretation of quantum mechanics (QM) has some degree of objectivity. It may be useful for researchers who are interested in quantum foundations, but do not belong to the QBism-community, because I tried to analyze essentials of QBism critically (i.e., not just emphasizing its advantages, as in a typical publication of QBists). QBists may be interested as well - in comments of an external observer who monitored development of this approach to QM during last 16 years. The second part of the paper is devoted to interpretations of probability, objective versus subjective, and view...

  1. Firm Search for External Knowledge

    DEFF Research Database (Denmark)

    Sofka, Wolfgang; Grimpe, Christoph

    2012-01-01

    The innovation performance of modern firms is increasingly determined by their ability to search and absorb external knowledge. However, after a certain threshold firms "oversearch" their environment and innovation performance declines. In this paper, we argue that prior literature has largely...... ignored the institutional context that provides or denies access to external knowledge at the country level. Combining institutional and knowledge search theory, we suggest that the market orientation of the institutional environment and the magnitude of institutional change influence when firms begin...... to experience the negative performance effects of oversearch. Based on a comprehensive sample of almost 8,000 firms from ten European countries, we find that institutions matter considerably for firms' search activity. Higher market orientation of institutions increases the effectiveness of firms' search...

  2. MGR External Events Hazards Analysis

    Energy Technology Data Exchange (ETDEWEB)

    L. Booth

    1999-11-06

    The purpose and objective of this analysis is to apply an external events Hazards Analysis (HA) to the License Application Design Selection Enhanced Design Alternative 11 [(LADS EDA II design (Reference 8.32))]. The output of the HA is called a Hazards List (HL). This analysis supersedes the external hazards portion of Rev. 00 of the PHA (Reference 8.1). The PHA for internal events will also be updated to the LADS EDA II design but under a separate analysis. Like the PHA methodology, the HA methodology provides a systematic method to identify potential hazards during the 100-year Monitored Geologic Repository (MGR) operating period updated to reflect the EDA II design. The resulting events on the HL are candidates that may have potential radiological consequences as determined during Design Basis Events (DBEs) analyses. Therefore, the HL that results from this analysis will undergo further screening and analysis based on the criteria that apply during the performance of DBE analyses.

  3. Network externalities across financial institutions

    OpenAIRE

    Castro Iragorri, Carlos Alberto; Preciado Pua, Sergio Andrés; Ordóñez Herrera, Juan Sebastián

    2016-01-01

    We propose and estimate a financial distress model that explicitly accounts for the interactions or spill-over effects between financial institutions, through the use of a spatial continuity matrix that is build from financial network data of inter bank transactions. Such setup of the financial distress model allows for the empirical validation of the importance of network externalities in determining financial distress, in addition to institution specific and macroeconomic covariates. The re...

  4. Externe Kosten in der Energiewirtschaft

    OpenAIRE

    Voß, Alfred; Friedrich, Rainer

    1994-01-01

    Als externe Effekte werden unbeteiligte Dritte betreffende Zusatzkosten oder Zusatznutzen verstanden, die sich in den jeweiligen Güterpreisen nicht wiederfinden und denen die Betroffenen nicht indifferent gegenüberstehen. Die gegenwärtige Energiebereitstellung und -nutzung ist in vielen Bereichen eine wesentliche Quelle der Belastung von Umwelt und Natur. Begriffe und Schlagworte wie Waldsterben, Tankerunglücke, Tschernobyl und Treibhauseffekt seien in diesem Zusammenhang erwähnt.

  5. Matching Games with Additive Externalities

    DEFF Research Database (Denmark)

    Branzei, Simina; Michalak, Tomasz; Rahwan, Talal

    2012-01-01

    Two-sided matchings are an important theoretical tool used to model markets and social interactions. In many real life problems the utility of an agent is influenced not only by their own choices, but also by the choices that other agents make. Such an influence is called an externality. Whereas......, optimistic, and pessimistic behaviour, and provide both computational hardness results and polynomial-time algorithms for computing stable outcomes....

  6. Treatment of nitrate-rich water in a baffled membrane bioreactor (BMBR) employing waste derived materials.

    Science.gov (United States)

    Basu, Subhankar; Singh, Saurabh K; Tewari, Prahlad K; Batra, Vidya S; Balakrishnan, Malini

    2014-12-15

    Nitrate removal in submerged membrane bioreactors (MBRs) is limited as intensive aeration (for maintaining adequate dissolved oxygen levels and for membrane scouring) deters the formation of anoxic zones essential for biological denitrification. The present study employs baffled membrane bioreactor (BMBR) to overcome this constraint. Treatment of nitrate rich water (synthetic and real groundwater) was investigated. Sludge separation was achieved using ceramic membrane filters prepared from waste sugarcane bagasse ash. A complex external carbon source (leachate from anaerobic digestion of food waste) was used to maintain an appropriate C/N ratio. Over 90% COD and 95% NO3-N reduction was obtained. The bagasse ash filters produced a clear permeate, free of suspended solids. Sludge aggregates were observed in the reactor and were linked to the high extracellular polymeric substances (EPS) content. Lower sludge volume index (40 mL/g compared to 150 mL/g for seed sludge), higher settling velocity (47 m/h compared to 10 m/h for seed sludge) and sludge aggregates (0.7 mm aggregates compared to filters in water treatment.

  7. Plasmonic external cavity laser refractometric sensor.

    Science.gov (United States)

    Zhang, Meng; Lu, Meng; Ge, Chun; Cunningham, Brian T

    2014-08-25

    Combining the high sensitivity properties of surface plasmon resonance refractive index sensing with a tunable external cavity laser, we demonstrate a plasmonic external cavity laser (ECL) for high resolution refractometric sensing. The plasmonic ECL utilizes a plasmonic crystal with extraordinary optical transmission (EOT) as the wavelength-selective element, and achieves single mode lasing at the transmission peak of the EOT resonance. The plasmonic ECL refractometric sensor maintains the high sensitivity of a plasmonic crystal sensor, while simultaneously providing a narrow spectral linewidth through lasing emission, resulting in a record high figure of merit for refractometric sensing with an active or passive optical resonator. We demonstrate single-mode and continuous-wave operation of the electrically-pumped laser system, and show the ability to measure refractive index changes with a 3σ detection limit of 1.79 × 10(-6) RIU. The demonstrated approach is a promising path towards label-free optical biosensing with enhanced signal-to-noise ratios for challenging applications in small molecule drug discovery and pathogen sensing.

  8. ENDOSCOPIC DCR VERSUS EXTERNAL DCR

    Directory of Open Access Journals (Sweden)

    Rukma

    2015-04-01

    Full Text Available PURPOSE: To compare success rates of endoscopic dacryocystorhinostomy (DCR and external DCR for acquired nasolacrimal duct obstruction (NLDO. MATERIALS AND METHODS: A prospective comparative non randomized study of 64 patients who presented with acquired NLD obstruction to a tertiary hospital. They were fully evaluated to ascertain the site of obstruction and patients with distal obstruction were included in the study. 34 patients underwent endoscopic DCR and 30 patients underwent external DCR RESULTS: 64 patients were included in the study and 72 procedures carried out. Success was achieved in 65 cases and failure in 7. Of the 7 failed cases, anatomical obstruction at the fistula site was found in 3, whereas functional failure was found in 4. In our patients, endoscopic DCR had a significantly higher success rate than external DCR, 95.23% versus 83.33% (P = 0.03. CONCLUSIONS: The success rate of Endoscopic DCR for acquired NLDO in our group of patients was 95.23%, with endoscopic surgery showing better results.

  9. Conceptual challenges for internalising externalities

    DEFF Research Database (Denmark)

    Miguel, Brandão; Weidema, Bo Pedersen

    2013-01-01

    We analyse a number of different externalities to identify conceptual challenges for the practical implementation of their internalisation. Three issues were identified: i) The balance between compensation and technology change and the respective effects on the nominal and real GDP; ii) The relev......We analyse a number of different externalities to identify conceptual challenges for the practical implementation of their internalisation. Three issues were identified: i) The balance between compensation and technology change and the respective effects on the nominal and real GDP; ii......) The relevance and efficiency of different instruments for internalisation and compensation; and iii) Implementing internalisation over large geographical and temporal distances. We find taxation to be a more relevant and efficient tool for internalisation than insurance and litigation. With increasing...... geographical and especially temporal distance between the benefitting actor and the victim of the external cost, the involvement of a non-governmental intermediate actor becomes increasingly necessary to provide the short-term capital required to ensure a successful implementation....

  10. Individuals' insight into intrapersonal externalities

    Directory of Open Access Journals (Sweden)

    David J. Stillwell

    2012-07-01

    Full Text Available An intrapersonal externality exists when an individual's decisions affect the outcomes of her future decisions. It can result in decreasing or increasing average returns to the rate of consumption, as occurs in addiction or exercise. Experimentation using the Harvard Game, which models intrapersonal externalities, has found differences in decision making between drug users and control subjects, leading to the argument that these externalities influence the course of illicit drug use. Nevertheless, it is unclear how participants who behave optimally conceptualise the problem. We report two experiments using a simplified Harvard Game, which tested the differences in contingency knowledge between participants who chose optimally and participants who did not. Those who demonstrated optimal performance exhibited both a pattern of correct responses and systematic errors to questions about the payoff schedules. The pattern suggested that they learned explicit knowledge of the change in reinforcement on a trail-by-trial basis. They did not have, or need, a full knowledge of the historical interaction leading to each payoff. We also found no evidence of choice differences between participants who were given a guaranteed payment and participants who were paid contingent on their performance, but those given a guaranteed payment were able to report more contingency knowledge as the experiment progressed, suggesting that they explored more rather than settling into a routine. Experiment 2 showed that using a fixed inter-trial interval did not change the results.

  11. Sperm motility of externally fertilizing fish and amphibians.

    Science.gov (United States)

    Browne, R K; Kaurova, S A; Uteshev, V K; Shishova, N V; McGinnity, D; Figiel, C R; Mansour, N; Agney, D; Wu, M; Gakhova, E N; Dzyuba, B; Cosson, J

    2015-01-01

    We review the phylogeny, sperm competition, morphology, physiology, and fertilization environments of the sperm of externally fertilizing fish and amphibians. Increased sperm competition in both fish and anurans generally increases sperm numbers, sperm length, and energy reserves. The difference between the internal osmolarity and iconicity of sperm cells and those of the aquatic medium control the activation, longevity, and velocity of sperm motility. Hypo-osmolarity of the aquatic medium activates the motility of freshwater fish and amphibian sperm and hyperosmolarity activates the motility of marine fish sperm. The average longevity of the motility of marine fish sperm (~550 seconds) was significantly (P fish sperm (~150 seconds), with the longevities of both marine and freshwater fish being significantly (P fish (140 μm/s) or freshwater fish (135 μm/s) sperm. The longevity of the sperm of giant salamanders (Cryptobranchoidea) of approximately 600 seconds was greater than that of freshwater fish sperm but much lower than anuran sperm. Our research and information from the literature showed that higher osmolarities promote greater longevity in anuran sperm, and some freshwater fish sperm, and that anuran and cryptobranchid sperm maintained membrane integrity long after the cessation of motility, demonstrating a preferential sharing of energy reserves toward the maintenance of membrane integrity. The maintenance of the membrane integrity of anuran sperm in fresh water for up to 6 hours showed an extremely high osmotic tolerance relative to fish sperm. The very high longevity and osmotic tolerance of anuran sperm and high longevity of cryptobranchid sperm, relative to those of freshwater fish, may reflect the complex fertilization history of amphibian sperm in general and anurans reversion from internal to external fertilization. Our findings provide a greater understanding of the reproductive biology of externally fertilizing fish and amphibians, and a

  12. Magnetized black holes in an external gravitational field

    Science.gov (United States)

    Kunz, Jutta; Nedkova, Petya; Yazadjiev, Stoytcho

    2017-07-01

    We obtain a family of exact solutions describing magnetized black holes in an external gravitational field. Locally the solutions can be interpreted as representing the near-horizon region of a black hole, which interacts with a surrounding matter distribution producing a strong magnetic field. Thus, the solutions reflect the influence of both a gravitational and an electromagnetic external potential in the strong field regime. The static members in the family are generalizations of the Schwarzschild solution in the described environment, while the rotating ones generalize the magnetized Reissner-Nordström solution when the influence of an external gravitational source is also taken into account. Technically, the solutions are obtained by means of a Harrison transformation, applied on the (electro-)vacuum distorted black holes constructed by Bretón et al. We examine the thermodynamical properties of the solutions, and compare them with the corresponding isolated black holes, and with the particular cases when the interaction with only one of the external potentials is taken into account. For the static black holes the influence of the external gravitational and magnetic fields is factorized in a sense, both affecting different properties, and leaving the rest intact. For the rotating solutions the external gravitational and magnetic fields are coupled through the conditions for avoiding conical singularities. The Meissner effect is observed for extremal rotating solutions only in the zero-charge limit, similar to the magnetized Reissner-Nordström black hole.

  13. Influence of external potentials on heterogeneous diffusion processes

    Science.gov (United States)

    Kazakevičius, Rytis; Ruseckas, Julius

    2016-09-01

    In this paper we consider heterogeneous diffusion processes with the power-law dependence of the diffusion coefficient on the position and investigate the influence of external forces on the resulting anomalous diffusion. The heterogeneous diffusion processes can yield subdiffusion as well as superdiffusion, depending on the behavior of the diffusion coefficient. We assume that not only the diffusion coefficient but also the external force has a power-law dependence on the position. We obtain analytic expressions for the transition probability in two cases: when the power-law exponent in the external force is equal to 2 η -1 , where 2 η is the power-law exponent in the dependence of the diffusion coefficient on the position, and when the external force has a linear dependence on the position. We found that the power-law exponent in the dependence of the mean square displacement on time does not depend on the external force; this force changes only the anomalous diffusion coefficient. In addition, the external force having the power-law exponent different from 2 η -1 limits the time interval where the anomalous diffusion occurs. We expect that the results obtained in this paper may be relevant for a more complete understanding of anomalous diffusion processes.

  14. Erythrocyte membrane proteins and membrane skeleton

    Institute of Scientific and Technical Information of China (English)

    LU Yiqin; LIU Junfan

    2007-01-01

    Considerable advances in the research field of erythrocyte membrane were achieved in the recent two decades.New findings in the structure-function correlation and interactions of erythrocyte membrane proteins have attracted extensive attention.Interesting progress was also made in the molecular pathogenesis of erythrocyte membrane disorders.Advances in the composition,function and interaction of erythrocyte membrane proteins,erythrocyte membrane skeleton,and relevant diseases are briefly described and summarized here on the basis of domestic and world literatures.

  15. Conformation of charged vesicles: the Debye Huckel and the low curvature limit

    Science.gov (United States)

    Sinha, Kumari Priti; Thaokar, Rochish M., , Prof.

    The shape as well as tension and pressure inside an uncharged vesicle are determined by the reduced volume. These parameters are important for a vesicle or a biological cell, since it can affect bio-physical processes such as osmosis and permeation, interaction with external agents such as bio- macromolecules and thermal fluctuations of the bilayer membrane of a vesicle. Charged membranes are ubiquitous in nature, most biological cell bio-membranes are charged, and therefore the knowledge of shape, tension and pressure of charged vesicles is critical. Additionally, the distribution of charges in the inner and outer leaflets is also important as it can affect the spatial interaction of a bilayer membrane with proteins. This work addresses these issues in the low charge and curvature limit. Our analysis indicates that despite a very strong two-way coupling between the charge and the curvature, the shapes of charged vesicles remain similar to that of uncharged vesicles at comparable reduced volumes, even for reasonable values of total charge. However, the tension and pressure values are higher, and are accurately estimated. Similarly the charge distribution on the outer and inner leaflet is strongly affected by the curvature. The value of spontaneous curvature due to charge redistribution is estimated. The insensitivity of the shape to charges persists even when only the outer leaflet is charged instead of charged inner and outer leaflets

  16. How to express tumours using membrane systems

    Institute of Scientific and Technical Information of China (English)

    Miguel A. Gutiérrez-Naranjo; Mario J. Pérez-Jiménez; Agustín Riscos-Nú(n)ez; Francisco J. Romero-Campero

    2007-01-01

    In this paper we discuss the potential usefulness of membrane systems as tools for modelling tumours. The approach is followed both from a macroscopic and a microscopic point of view. In the first case, one considers the tumour as a growing mass of cells,focusing on its external shape. In the second case, one descends to the microscopic level, studying molecular signalling pathways that are crucial to determine if a cell is cancerous or not. In each of these approaches we work with appropriate variants of membrane systems.

  17. Omniphobic Polyvinylidene Fluoride (PVDF) Membrane for Desalination of Shale Gas Produced Water by Membrane Distillation.

    Science.gov (United States)

    Boo, Chanhee; Lee, Jongho; Elimelech, Menachem

    2016-11-15

    Microporous membranes fabricated from hydrophobic polymers such as polyvinylidene fluoride (PVDF) have been widely used for membrane distillation (MD). However, hydrophobic MD membranes are prone to wetting by low surface tension substances, thereby limiting their use in treating challenging industrial wastewaters, such as shale gas produced water. In this study, we present a facile and scalable approach for the fabrication of omniphobic polyvinylidene fluoride (PVDF) membranes that repel both water and oil. Positive surface charge was imparted to an alkaline-treated PVDF membrane by aminosilane functionalization, which enabled irreversible binding of negatively charged silica nanoparticles (SiNPs) to the membrane through electrostatic attraction. The membrane with grafted SiNPs was then coated with fluoroalkylsilane (perfluorodecyltrichlorosilane) to lower the membrane surface energy. Results from contact angle measurements with mineral oil and surfactant solution demonstrated that overlaying SiNPs with ultralow surface energy significantly enhanced the wetting resistance of the membrane against low surface tension liquids. We also evaluated desalination performance of the modified membrane in direct contact membrane distillation with a synthetic wastewater containing surfactant (sodium dodecyl sulfate) and mineral oil, as well as with shale gas produced water. The omniphobic membrane exhibited a stable MD performance, demonstrating its potential application for desalination of challenging industrial wastewaters containing diverse low surface tension contaminants.

  18. A Comparison between External versus Internal Lateral Osteotomy in Rhinoplasty

    Directory of Open Access Journals (Sweden)

    M Hashemi

    2005-01-01

    Full Text Available Background: Lateral osteotomy is a major part of rhinoplasty for remodeling external facet of the nose and narrowing of nasal base and dorsum after removal of the hump. There are two techniques for lateral osteotomy known as external and internal. Each of these provide advantages and impose limitations. The purpose of our study was to compare the severity of postoperative edema and ecchymosis between internal and external osteotomy techniques. Methods: This study was designed as a clinical trial on 30 cases. With randomization, one side of the nasal bone was selected for internal approach, and the other side, for external approach. Then, on the 1st and 7th days after surgery, the patients were scored for the severity of edema and ecchymosis. Results: On the first day after surgery, not only edema, but also ecchymosis was lower with the external osteotomy than with the internal approach (P = 0.037, P = 0.002, respectively. The severity of ecchymosis, on the 7th postoperative day, was lower with the external approach, and the difference was significant (P = 0.011. The severity of both edema and ecchymosis on the first postoperative day was evaluated higher in females, with statistically significant differences (P = 0.05 for edema and P = 0.003 for ecchymosis. The extension of ecchymosis on the 7th postoperative day was higher in women (P = 0.05. There were no significant differences between the two approaches in medialization of the involved bones and no apparent asymmetries either. Conclusion: According to the results of this study, external osteotomy seems to be the approach of choice, provided that the surgeon has enough experience in doing it. Keywords: Rhinoplasty, Internal osteotomy, External osteotomy, Ecchymosis, Edema

  19. Measuring shape fluctuations in biological membranes

    Science.gov (United States)

    Monzel, C.; Sengupta, K.

    2016-06-01

    Shape fluctuations of lipid membranes have intrigued cell biologists and physicists alike. In the cellular context, their origin—thermal or active—and their physiological significance are open questions. These small incessant displacements, also called membrane undulations, have mostly been studied in model membranes and membranes of simple cells like erythrocytes. Thermal fluctuations of such membranes have been very well described both theoretically and experimentally; active fluctuations are a topic of current interest. Experimentally, membrane fluctuations are not easy to measure, the main challenge being to develop techniques which are capable of measuring very small displacements at very high speed, and preferably over a large area and long time. Scattering techniques have given access to fluctuations in membrane stacks and a variety of optical microscopy based techniques have been devised to study membrane fluctuations of unilamellar vesicles, erythrocytes and other cells. Among them are flicker spectroscopy, dynamic light scattering, diffraction phase microscopy and reflection interference contrast microscopy. Each of these techniques has its advantages and limitations. Here we review the basic principles of the major experimental techniques used to measure bending or shape fluctuations of biomembranes. We report seminal results obtained with each technique and highlight how these studies furthered our understanding of physical properties of membranes and their interactions. We also discuss suggested role of membrane fluctuations in different biological processes.

  20. Antigen digestion on the target plate of MALDI-TOF MS after isolation using an immunoaffinity membrane.

    Science.gov (United States)

    Shimazaki, Youji; Nishimura, Yuri; Saito, Masaki

    2013-09-01

    A combination of methods is required to achieve separation of intact proteins and subsequently perform structure analysis to examine their unstable or external structures. The aim of this study was to develop a method of structure analysis in intact proteins after purification. Transferrin from human plasma was trapped by membrane-immobilized anti-transferrin antibody, which was produced by non-denaturing two-dimensional electrophoresis (2-DE), and transferred to a polyvinylidene fluoride (PVDF) membrane and stained with Ponceau S. The antigen transferrin was eluted by rinsing the membrane with trifluoroacetic acid (TFA) or aspartic acid. In addition, a method was established by which the purified human transferrin was enzymatically digested on a matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) target plate. Thus, after purification of the human transferrin antigen from tens of microlitres of human plasma using an immunoaffinity membrane, transferrin polypeptide fragments were obtained on the plate following digestion with pepsin in the presence of 0.1% TFA or endoproteinase Lys-C or Lys-C/trypsin with 0.001% sodium dodecyl sulphate (SDS). The results indicated that the combined methods of isolation using an immunoaffinity membrane and enzymatic digestion on a MALDI-TOF MS plate could be applied to the purification and microanalysis of antigens. This approach would be particularly applicable to the analysis of the primary structure and the less stable and highly accessible regions of antigens from limited sample volumes.

  1. Magnetically controlled permeability membranes

    KAUST Repository

    Kosel, Jurgen

    2013-10-31

    A bioactive material delivery system can include a thermoresponsive polymer membrane and nanowires distributed within the thermoresponsive polymer membrane. Magnetic activation of a thermoresponsive polymer membrane can take place via altering the magnetization or dimensions of nanowires dispersed or ordered within the membrane matrix.

  2. Compositional asynchronous membrane systems

    Institute of Scientific and Technical Information of China (English)

    Cosmin Bonchis; Cornel Izbasa; Gabriel Ciobanu

    2007-01-01

    This paper presents an algorithmic way of building complex membrane systems by coupling elementary membranes. Its application seems particularly valuable in the case of asynchronous membrane systems, since the resulting membrane system remains asynchronous. The composition method is based on a handshake mechanism implemented by using antiport rules and promoters.

  3. Composite sensor membrane

    Science.gov (United States)

    Majumdar, Arun; Satyanarayana, Srinath; Yue, Min

    2008-03-18

    A sensor may include a membrane to deflect in response to a change in surface stress, where a layer on the membrane is to couple one or more probe molecules with the membrane. The membrane may deflect when a target molecule reacts with one or more probe molecules.

  4. Materials for next-generation desalination and water purification membranes

    Science.gov (United States)

    Werber, Jay R.; Osuji, Chinedum O.; Elimelech, Menachem

    2016-05-01

    Membrane-based separations for water purification and desalination have been increasingly applied to address the global challenges of water scarcity and the pollution of aquatic environments. However, progress in water purification membranes has been constrained by the inherent limitations of conventional membrane materials. Recent advances in methods for controlling the structure and chemical functionality in polymer films can potentially lead to new classes of membranes for water purification. In this Review, we first discuss the state of the art of existing membrane technologies for water purification and desalination, highlight their inherent limitations and establish the urgent requirements for next-generation membranes. We then describe molecular-level design approaches towards fabricating highly selective membranes, focusing on novel materials such as aquaporin, synthetic nanochannels, graphene and self-assembled block copolymers and small molecules. Finally, we highlight promising membrane surface modification approaches that minimize interfacial interactions and enhance fouling resistance.

  5. Electrospun polyvinyl alcohol-polyvinyl pyrrolidone nanofibrous membranes for interactive wound dressing application.

    Science.gov (United States)

    Shankhwar, Nisha; Kumar, Manishekhar; Mandal, Biman B; Robi, P S; Srinivasan, A

    2016-01-01

    Cross-linked polyvinyl alcohol (PVA) and polyvinyl pyrrolidone (PVP) composite nanofibrous membranes have been prepared by electrospinning. Mechanical properties of the membranes improved significantly with PVP addition. PVP improved hydrophilicity and sustainable degradation of the membranes. Biocompatibility of the membranes was assessed by in vitro culture of native skin cells (L929 fibroblast and HaCaT keratinocytes). Tests showed sustained release of the antibiotic ciprofloxacin hydrochloride monohydrate by the membranes. Further, zone of inhibition study against Staphylococcus aureus growth demonstrated protective action against external pathogenic microbes. These studies show these simple PVA-PVP nanofibrous membranes are promising interactive antibiotic-eluting wound dressing materials.

  6. Limits on $\

    CERN Document Server

    Perego, D L

    2002-01-01

    A limit on the tau neutrino mass is obtained using all the $Z^{0} \\to \\tau^{+} \\tau^{-}$ data collected at LEP by the DELPHI detector between 1992 and 1995. In this analysis events in which one of the taus decays into one charged particle, while the second $\\tau$ decays into f{}ive charged pions (1-5 topology) have been used. The neutrino mass is determined from a bidimensional \\fit ~on the invariant mass $m^{*}_{5 \\pi}$ and on the energy $E_{5 \\pi}$ of the f{}ive $\\pi^{\\pm}$ system. The result found is $m_{\

  7. Black Holes: The Membrane Viewpoint

    Science.gov (United States)

    Thorne, Kip S.

    Contents: I. Introduction: 1. Overview of the membrane viewpoint. 2. History of research on the membrane viewpoint. II. The 3+1 split of spacetime: 1. ZAMOs and the 3+1 split of the metric. 2. Gravitoelectric and gravitomagnetic fields. 3. 3+1 split of electrodynamics. III. Stretching the horizon and black-hole thermodynamics: 1. Macdonald's vibrating magnetic field problem. 2. Stretching the horizon. 3. The entropy of a black hole. 4. The thermodynamics and mechanics of a black hole. IV. Electrodynamics of the stretched horizon: 1. The laws of Gauss, Ampere, Ohm, and charge conservation. 2. Lorentz force and ohmic dissipation in the stretched horizon. V. Some electromagnetic model problems: 1. Charge separation in the stretched horizon. 2. Black hole as a resistor in an electric circuit. 3. Black hole as the rotor in an electric motor. 4. Rotating hole immersed in a time-independent, vacuum magnetic field. 5. Magnetized, rotating hole as a battery for an external circuit. VI. Astrophysical applications of the membrane formalism. VII. Conclusion.

  8. Bioinspired Multifunctional Membrane for Aquatic Micropollutants Removal.

    Science.gov (United States)

    Cao, Xiaotong; Luo, Jianquan; Woodley, John M; Wan, Yinhua

    2016-11-09

    Micropollutants present in water have many detrimental effects on the ecosystem. Membrane technology plays an important role in the removal of micropollutants, but there remain significant challenges such as concentration polarization, membrane fouling, and variable permeate quality. The work reported here uses a multifunctional membrane with rejection, adsorption, and catalysis functions to solve these problems. On the basis of mussel-inspired chemistry and biological membrane properties, a multifunctional membrane was prepared by applying "reverse filtration" of a laccase solution and subsequent "dopamine coating" on a nanofiltration (NF) membrane support, which was tested on bisphenol A (BPA) removal. Three NF membranes were chosen for the preparation of the multifunctional membranes on the basis of the membrane properties and enzyme immobilization efficiency. Compared with the pristine membrane, the multifunctional membrane exhibited significant improvement of BPA removal (78.21 ± 1.95%, 84.27 ± 7.30%, and 97.04 ± 0.33% for NT103, NF270, and NF90, respectively), all of which are clearly superior to the conventional Fenton treatment (55.0%) under similar conditions and comparable to soluble laccase coupled with NF270 membrane filtration (89.0%). The improvement would appear to be due to a combination of separation (reducing the enzymatic burden), adsorption (enriching the substrate concentration as well as prolonging the residence time), and lastly, catalysis (oxidizing the pollutants and breaking the "adsorption saturation limits"). Furthermore, the synergistic effect of the polydopamine (PDA) layer on the enzymatic oxidation of BPA was confirmed, which was due to its enhanced adsorption and electron transfer performance. The multifunctional membrane could be reused for at least seven cycles with an acceptable activity loss, demonstrating good potential for removal of micropollutants.

  9. Skepticism, Contextualism, Externalism and Modality

    Directory of Open Access Journals (Sweden)

    Ron Wilburn

    2006-12-01

    Full Text Available In this paper, I argue for the following claims. Contextualist strategies to tame or localize epistemic skepticism are hopeless if contextualist factors are construed internalistically. However, because efforts to contextualize externalism via subjunctive conditional analysis court circularity, it is only on an internalistic interpretation that contextualist strategies can even be motivated. While these claims do not give us an argument for skepticism, they do give us an argument that contextualism, as such, is not likely to provide us with an argument against skepticism.

  10. Cranial arachnoid membranes: some aspects of microsurgical anatomy.

    Science.gov (United States)

    Lü, Jian; Zhu, Xian-Li

    2007-07-01

    Although the arachnoid membranes have been known for more than 300 years, the anatomy of the arachnoid membranes has not been studied in detail. This study was performed to explore the microanatomical features of the cranial arachnoid membranes. The arachnoid membranes and cisterns were observed in eight Han Chinese adult human cadaveric brains with an operating microscope, without staining of intracranial structures or injection of colored material into blood vessels. Twenty seven arachnoid membranes and 21 subarachnoid cisterns were identified. The topographical features of each arachnoid membrane were described. On the basis of the arachnoid membranes we identified, the arachnoidal limits of the cisterns were discussed. The microsurgical anatomical research on the arachnoid membranes is a supplement to the anatomical study of the subarachnoid cisterns. The understanding of the topographical features of the arachnoid membranes is valuable to the reasonable dissection of the cisterns and the minimally invasive manipulations during microsurgical procedures.

  11. High temperature catalytic membrane reactors

    Energy Technology Data Exchange (ETDEWEB)

    1990-03-01

    Current state-of-the-art inorganic oxide membranes offer the potential of being modified to yield catalytic properties. The resulting modules may be configured to simultaneously induce catalytic reactions with product concentration and separation in a single processing step. Processes utilizing such catalytically active membrane reactors have the potential for dramatically increasing yield reactions which are currently limited by either thermodynamic equilibria, product inhibition, or kinetic selectivity. Examples of commercial interest include hydrogenation, dehydrogenation, partial and selective oxidation, hydrations, hydrocarbon cracking, olefin metathesis, hydroformylation, and olefin polymerization. A large portion of the most significant reactions fall into the category of high temperature, gas phase chemical and petrochemical processes. Microporous oxide membranes are well suited for these applications. A program is proposed to investigate selected model reactions of commercial interest (i.e. dehydrogenation of ethylbenzene to styrene and dehydrogenation of butane to butadiene) using a high temperature catalytic membrane reactor. Membranes will be developed, reaction dynamics characterized, and production processes developed, culminating in laboratory-scale demonstration of technical and economic feasibility. As a result, the anticipated increased yield per reactor pass economic incentives are envisioned. First, a large decrease in the temperature required to obtain high yield should be possible because of the reduced driving force requirement. Significantly higher conversion per pass implies a reduced recycle ratio, as well as reduced reactor size. Both factors result in reduced capital costs, as well as savings in cost of reactants and energy.

  12. Empirical Evaluation On External Debt Of Malaysia

    OpenAIRE

    Nor’Aznin Abu Bakar; Sallahuddin Hassan

    2011-01-01

    This study analyzes the effects of external debts on economic growth in Malaysia. The analysis is conducted both at aggregate and disaggregate levels. The empirical results are based on VAR estimates using GDP, external debts, capital accumulation, labor force and human capital. Estimation results at the aggregate level indicate that total external debts affect economic growth positively. In particular, one percentage point increase in total external debts generates 1.29 percentage point of e...

  13. Thermo-induced vesicular dynamics of membranes containing cholesterol derivatives.

    Science.gov (United States)

    Yoda, Tsuyoshi; Vestergaard, Mun'delanji C; Hamada, Tsutomu; Le, Phuc Thi Minh; Takagi, Masahiro

    2012-08-01

    Membrane structural organization is an intrinsic property of a cell membrane. Any changes in lipid composition, and/or any stimuli that affect molecular packing induce structural re-organization. It membrane dynamics provide a means by which changes in structure organization can be determined, upon a change in the membrane internal or external environment. Here, we report on the effect of thermo-stress on membranes containing cholesterol liquid crystal (LC) compounds cholesterol benzoate (BENZO) and oxidized cholesterols. We have (1) revealed that lipid vesicles containing this artificial cholesterol derivative (BENZO) is thermo-responsive, and that this thermo-sensitivity is significantly similar to naturally oxy-cholesterols (2) elucidated the mechanism behind the membrane perturbation. Using Langmuir monolayer experiments, we have demonstrated that membrane perturbation was due to an increase in the molecular surface area, (3) discussed the similarities between cholesterol benzoate in the cholesterol LC state and in lipid bilayer membranes. Last, (4) drawing from previously reported findings, our new data on membrane dynamics, and the discussion above, we propose that artificial cholesterol derivatives such as BENZO, open new possibilities for controlled and tailored design using model membrane systems. Examples could include the development of membrane technology and provide a trigger for progress in thermo-tropical liquid crystal engineering.

  14. The effect of electric fields on lipid membranes

    CERN Document Server

    Vasilkoski, Z

    2006-01-01

    Contrary to existing theoretical models, experimental evidence points out that electroporation (membrane defect formation under external electric fields) starts to occur within the range of transmembrane voltages that cells may routinely experience, curiously, just above the range of transmembrane voltages involved in neural signal transmission. Understanding the underlying principles of electric fields-lipid membrane interactions seems to carry a great biological importance. An argument is presented toward understanding the theoretical aspects of electroporation by using the DLVO theory, which has not been recognized previously in the context of electroporation. Further, the dispersion interactions (with its quantum nature), of the double layer counterions and membrane lipid molecules over the Stern layer are emphasized. The sign of these forces is such that they compress the membrane. A parallel is drawn to the theory of thin films. The argument is that the external electric field breaks the symmetry of the...

  15. Tuning plasmonic cloaks with an external magnetic field

    CERN Document Server

    Kort-Kamp, W J M; Pinheiro, F A; Farina, C

    2013-01-01

    We propose a mechanism to actively tune the operation of plasmonic cloaks with an external magnetic field by investigating electromagnetic scattering by a dielectric cylinder coated with a magneto-optical shell. In the long wavelength limit we show that the presence of an external magnetic field may drastically reduce the scattering cross-section at all observation angles. We demonstrate that the application of external magnetic fields can modify the operation wavelength without the need of changing material and/or geometrical parameters. We also show that applied magnetic fields can reversibly switch on and off the cloak operation. These results, which could be achieved for existing magneto-optical materials, are shown to be robust to material losses, so that they may pave the way for developing actively tunable, versatile plasmonic cloaks.

  16. External cavity beam combining of 21 semiconductor lasers using SPGD.

    Science.gov (United States)

    Montoya, Juan; Augst, Steven J; Creedon, Kevin; Kansky, Jan; Fan, Tso Yee; Sanchez-Rubio, Antonio

    2012-04-10

    Active coherent beam combining of laser oscillators is an attractive way to achieve high output power in a diffraction limited beam. Here we describe an active beam combining system used to coherently combine 21 semiconductor laser elements with an 81% beam combining efficiency in an external cavity configuration compared with an upper limit of 90% efficiency in the particular configuration of the experiment. Our beam combining system utilizes a stochastic parallel gradient descent (SPGD) algorithm for active phase control. This work demonstrates that active beam combining is not subject to the scaling limits imposed on passive-phasing systems.

  17. Quantum Electrodynamics on background external fields

    CERN Document Server

    Marecki, P

    2003-01-01

    The quantum electrodynamics in presence of background external fields is developed. Modern methods of local quantum physics allow to formulate the theory on arbitrarily strong possibly time-dependent external fields. Non-linear observables which depend only locally on the external field are constructed. The tools necessary for this formulation, the parametrices of the Dirac operator, are investigated.

  18. 46 CFR 154.452 - External pressure.

    Science.gov (United States)

    2010-10-01

    ... 46 Shipping 5 2010-10-01 2010-10-01 false External pressure. 154.452 Section 154.452 Shipping... Independent Tank Type C and Process Pressure Vessels § 154.452 External pressure. The design external pressure...) for tanks without a vacuum relief valve. P2=0, or the pressure relief valve setting for an enclosed...

  19. 46 CFR 64.19 - External pressure.

    Science.gov (United States)

    2010-10-01

    ... 46 Shipping 2 2010-10-01 2010-10-01 false External pressure. 64.19 Section 64.19 Shipping COAST... HANDLING SYSTEMS Standards for an MPT § 64.19 External pressure. (a) A tank without a vacuum breaker must be designed to withstand an external pressure of 71/2 psig or more. (b) A tank with a vacuum breaker...

  20. 49 CFR 195.108 - External pressure.

    Science.gov (United States)

    2010-10-01

    ... 49 Transportation 3 2010-10-01 2010-10-01 false External pressure. 195.108 Section 195.108 Transportation Other Regulations Relating to Transportation (Continued) PIPELINE AND HAZARDOUS MATERIALS SAFETY... PIPELINE Design Requirements § 195.108 External pressure. Any external pressure that will be exerted on the...

  1. Quantum electrodynamics on background external fields

    OpenAIRE

    2003-01-01

    The quantum electrodynamics in presence of background external fields is developed. Modern methods of local quantum physics allow to formulate the theory on arbitrarily strong possibly time-dependent external fields. Non-linear observables which depend only locally on the external field are constructed. The tools necessary for this formulation, the parametrices of the Dirac operator, are investigated.

  2. Sheet Membrane Spacesuit Water Membrane Evaporator

    Science.gov (United States)

    Bue, Grant; Trevino, Luis; Zapata, Felipe; Dillion, Paul; Castillo, Juan; Vonau, Walter; Wilkes, Robert; Vogel, Matthew; Frodge, Curtis

    2013-01-01

    A document describes a sheet membrane spacesuit water membrane evaporator (SWME), which allows for the use of one common water tank that can supply cooling water to the astronaut and to the evaporator. Test data showed that heat rejection performance dropped only 6 percent after being subjected to highly contaminated water. It also exhibited robustness with respect to freezing and Martian atmospheric simulation testing. Water was allowed to freeze in the water channels during testing that simulated a water loop failure and vapor backpressure valve failure. Upon closing the backpressure valve and energizing the pump, the ice eventually thawed and water began to flow with no apparent damage to the sheet membrane. The membrane evaporator also serves to de-gas the water loop from entrained gases, thereby eliminating the need for special degassing equipment such as is needed by the current spacesuit system. As water flows through the three annular water channels, water evaporates with the vapor flowing across the hydrophobic, porous sheet membrane to the vacuum side of the membrane. The rate at which water evaporates, and therefore, the rate at which the flowing water is cooled, is a function of the difference between the water saturation pressure on the water side of the membrane, and the pressure on the vacuum side of the membrane. The primary theory is that the hydrophobic sheet membrane retains water, but permits vapor pass-through when the vapor side pressure is less than the water saturation pressure. This results in evaporative cooling of the remaining water.

  3. Modification and Applications of Hydrophilic Polypropylene Membrane

    Science.gov (United States)

    Ariono, Danu; Kusuma Wardani, Anita

    2017-07-01

    Polypropylene (PP) is one of the most important polymers for microporous membrane due to its high void volume, well-controlled porosity, high thermal and chemical stability, and low cost. However, the hydrophobicity of PP becomes a limitation to broaden its applications. Furthermore, membrane fouling occurs more seriously on hydrophobic membranes than hydrophilic ones. To solve this problem, surface modifications have been developed to enhance PP membrane hydrophilicity without changing its bulk properties. Graft polymerization and plasma treatment are the most popular techniques for surface hydrophilization. Some studies showed that highly hydrophilic PP membranes with water contact angle less than 20° could be obtained by plasma treatment and graft polymerization. Furthermore, during plasma treatment, polar groups were formed on the PP membrane surface thus increased water uptake. To bring brief explanation on various research trends for PP modification, this paper provides a review of surface hydrophilization of microporous PP membrane, including plasma treatment and graft polymerization. The effects of surface modification on PP membrane performance such as porosity, water contact angle, and water flux are also discussed. In addition, the applications of modified PP membrane are presented as well.

  4. Effect of nitrate supply and mycorrhizal inoculation on characteristics of tobacco root plasma membrane vesicles.

    Science.gov (United States)

    Moche, Martin; Stremlau, Stefanie; Hecht, Lars; Göbel, Cornelia; Feussner, Ivo; Stöhr, Christine

    2010-01-01

    Plant plasma membrane (pm) vesicles from mycorrhizal tobacco (Nicotiana tabacum cv. Samsun) roots were isolated with negligible fungal contamination by the aqueous two-phase partitioning technique as proven by fatty acid analysis. Palmitvaccenic acid became apparent as an appropriate indicator for fungal membranes in root pm preparations. The pm vesicles had a low specific activity of the vanadate-sensitive ATPase and probably originated from non-infected root cells. In a phosphate-limited tobacco culture system, root colonisation by the vesicular arbuscular mycorrhizal fungus, Glomus mosseae, is inhibited by external nitrate in a dose-dependent way. However, detrimental high concentrations of 25 mM nitrate lead to the highest colonisation rate observed, indicating that the defence system of the plant is impaired. Nitric oxide formation by the pm-bound nitrite:NO reductase increased in parallel with external nitrate supply in mycorrhizal roots in comparison to the control plants, but decreased under excess nitrate. Mycorrhizal pm vesicles had roughly a twofold higher specific activity as the non-infected control plants when supplied with 10-15 mM nitrate.

  5. Hyposmotic membrane stretch potentiated muscarinic receptor agonist-induced depolarization of membrane potential in guinea-pig gastric myocytes

    Institute of Scientific and Technical Information of China (English)

    Lin Li; Nan-Ge Jin; Lin Piao; Ming-Yu Hong; Zheng-Yuan Jin; Ying Li; Wen-Xie Xu

    2002-01-01

    AIM: To investigate the relationship betweenhyposmotic membrane stretch and muscarinic receptoragonist-induced depolarization of membrane potentialin antral gastric circular myocytes of guinea-pig.METHODS: Using whole cell patch-clamp techniquerecorded membrane potential and current in singlegastric myocytes isolated by collagena se.RESULTS: Hyposmotic membrane stretch hyperpolarizedmembrane potential from -60.0mV±1.0mV to -67.9mV±1.0mV. TEA (10mmol/L), a nonselective potassiumchannel blocker significantly inhibited hyposmoticmembrane stretch-induced hyperpolarization. After KCIin the pipette and NaCI in the external solution werereplaced by CsCI to block the potassium current,hyposmotic membrane stretch depolarized the membranepotential from -60.0 mV±-1.0mV to -44.8 mV±2.3mV(P<0.05), and atropine (1 pmol/L) inhibited thedepolarization of the membrane potential. Muscarinicreceptor agonist Carbachol depolarized membranepotential from -60.0mV±1.0mV to -50.3 mV±0.3mV(P<0.05) and hyposmotic membrane stretchpotentiated the depolarization. Carbachol inducedmuscarinic current (Icch) was greatly increased byhyposmotic membrane stretch.CONCLUSION: Hyposmotic membrane stretchpotentiated muscarinic receptor agonist-induceddepolarization of membrane potential, which is relatedto hyposmotic membrane stretch-induced increase ofmuscarinic current.

  6. The external scanning proton microprobe of Firenze: A comprehensive description

    Science.gov (United States)

    Giuntini, L.; Massi, M.; Calusi, S.

    2007-06-01

    An external proton scanning microbeam setup is installed on the -30° line of the new 3 MV tandem accelerator in Firenze; the most relevant features of the line, such as detection setup for IBA measurements, target viewing system, beam diagnostic and transport are described here. With our facility we can work with a beam spot on sample better than 10 μm full-width half-maximum (FWHM) and an intensity of some nanoamperes. Standard beam exit windows are silicon nitride (Si 3N 4) TEM membranes, 100 nm thick and 0.5×0.5 mm 2 wide; we also successfully performed measurements using membranes 1×1 mm 2 wide, 100 nm thick, and 2×2 mm 2 wide, 200 and 500 nm thick. Exploiting the yield of Si X-rays produced by the beam in the exit window as an indirect measurement of the charge, a beam charge monitor system was implemented. The analytical capabilities of the microbeam have been extended by integrating a two-detector PIXE setup with BS and PIGE detectors; the external scanning proton microprobe in Firenze is thus a powerful instrument to fully characterize samples by ion beam analysis, through the simultaneous collection of PIXE, PIGE and BS elemental maps. Its characteristics can make it often competitive with traditional in vacuum microbeam for measurements of thick targets.

  7. Application of optical controlling methods for plants under external influence

    Science.gov (United States)

    Timchenko, E. V.; Taskina, L. A.

    2012-10-01

    The experimental study results of spectral characteristic change of different types of plants influenced by external factors (synthetic superficially active substances, salts of heavy metals and nitrate fertilizers) are presented. Differential optical factor was used as the monitored optical parameter that characterizes the chlorophyll concentration change. The differential backscatter method which has high test-sensitivity and provides with the most complete information on the plant condition was the main optical monitoring method. For understanding the mechanisms of external factor accumulation and influence on plants the confocal fluorescent microscopy method providing contrast micrographs of high resolution was used for microscopic analysis in the study. It was revealed that synthetic superficially active substances and heavy metal presence lead to quasilinear decrease of differential backscatter factor with time. It was shown that the presence of salts of heavy metals in a water solution leads to chlorophyll "binding" which is microscopically shown as their «adhesion» near the cell membranes. On the contrary, the presence of synthetic superficially active substances maintains the uniformity of chlorophyll distribution in a cell, but its concentration falls with increasing the concentration in a major emission. The latter depends on the fact that synthetic superficially active substances solubilize the cell membrane proteins, increasing its penetrability. It causes pigment release ("washing away") from a plant, thereby leading to differential optical factor change. It was shown that nitrate fertilizer presence leads to increase of differential backscatter factor with time which is microscopically connected to increase in chlorophyll concentration.

  8. Electrode-analytical properties of polyvinylchloride membranes based on triple metal-polymeric complexes

    Directory of Open Access Journals (Sweden)

    Katerina V. Matorina

    2015-10-01

    Full Text Available The influence of the nature of the electrode-active substances (EAS, the composition of the external and internal solutions on the formation of the analytical signal of polyvinylchloride (PVC membranes based on associates and triple metal-polymeric complexes (TMPC was established. Dehumidification of synthesized membranes increases with the content of polyvinylpyrrolidone (PVP. The value of the swelling degree is more than two times greater for membranes, which contain as EAS TMPC, relative to membranes based on associates. The value of water absorption of membranes is determined by the nature of EAS. They formed a series of increasing of the swelling degree such as associate < background membrane < TMPC. Swelling of the background membrane is explained by the physical sorption of water molecules on the surface of plasticized membrane. Hydration of PVP macromolecules varies with the introduction of metal ions, macromolecules unit undergoes a conformational transition. PVP macromolecules form tunnels or cavities where complex particles distributed and additional water accumulated through the second coordination layer. Constructed sensors based on TMPC have slope of electrode function equal to 25 mV/pC. Linear dependence of potential on the polymer concentration is observed in the range of 5–7 pC units. Sensors based on associates have slope of the electrode function of 20–25 mV/pC that can be varied depending on the nature of the EAS. Working range is 4–8 pC. Response time of sensor is less than 1 min. The optimal time for conditioning of the synthesized PVC membrane is 24 hours. Potentiometric sensors have been developed for the determination of residual amounts of low molecular PVP which is a food additive E 1201 commonly used for thickening, stabilizing and clarifying of food products. The content of PVP was determined in real objects (apple juice, beer, red wine and cognac with using the polyvinylpyrrolidone sensors (Sr < 0.08. The

  9. Artificial cell membranes for diagnostics and therapeutics

    Energy Technology Data Exchange (ETDEWEB)

    Charych, D.; Nagy, J.O. [Lawrence Berkeley National Lab., CA (United States)

    1996-09-01

    Receptors on the membrane can recognize and bind extracellular molecules and convert that event into signals that elicit molecular changes within the cell. These two properties alone--molecular recognition and signal transduction--make the cell membrane an attractive model for designing novel biosensors or therapeutics. Natural cell membranes, however, are highly complex; mimicking the intricate choreography of the cell`s daily activities would be a daunting task. Instead, the authors turn to simpler, synthetic versions of the cell, where they can build in the components that give rise to specific activities and functions, one at a time. The process of forming artificial membranes is identical to that of forming natural membranes and is sometimes referred to as molecular self-assembly. From a practical point of view, the process is simple, because no external intervention is required--the molecules organize themselves into useful structures. The molecules that constitute the membranes are amphiphilic and therefore will spontaneously form lipid aggregates when mixed with water.

  10. Preparation and gas permeabilities of zeolite membranes

    Energy Technology Data Exchange (ETDEWEB)

    Jinqu Wang; Yongfeng Wang; Shuanshi Fan [Dalian Univ. of Technology (China)] [and others

    1994-12-31

    Zeolites with less than 10 {angstrom} pore are desirable membrane materials, due to their crystallinity, resistance to high temperature, and chemical inertness. A variety of new membranous materials were synthesized composed of a continuous intergrowth of 5-50 micrometer type A, X, Y, or ZSM-5 crystals. The membranes were crystallized under hydrothermal conditions at 90 to 220{degrees}C on the external surface of a porous ceramics. The reagents used were aluminum sulphate, water glass (20.1 wt% SiO{sub 2}, 6.09 wt% Na{sub 2}O, 73.8 wt% water), sodium hydroxide, sulphuric acid, deionized water and templating agents. The molar composition was: 0.1-0.5 Na{sub 2}O:1 SiO{sub 2}:0.04-0.05 Al{sub 2}O{sub 3}:20-60H{sub 2}O.

  11. Design of Asymmetric Peptide Bilayer Membranes.

    Science.gov (United States)

    Li, Sha; Mehta, Anil K; Sidorov, Anton N; Orlando, Thomas M; Jiang, Zhigang; Anthony, Neil R; Lynn, David G

    2016-03-16

    Energetic insights emerging from the structural characterization of peptide cross-β assemblies have enabled the design and construction of robust asymmetric bilayer peptide membranes. Two peptides differing only in their N-terminal residue, phosphotyrosine vs lysine, coassemble as stacks of antiparallel β-sheets with precisely patterned charged lattices stabilizing the bilayer leaflet interface. Either homogeneous or mixed leaflet composition is possible, and both create nanotubes with dense negative external and positive internal solvent exposed surfaces. Cross-seeding peptide solutions with a preassembled peptide nanotube seed leads to domains of different leaflet architecture within single nanotubes. Architectural control over these cross-β assemblies, both across the bilayer membrane and along the nanotube length, provides access to highly ordered asymmetric membranes for the further construction of functional mesoscale assemblies.

  12. Age Limits.

    Science.gov (United States)

    Antfolk, Jan

    2017-03-01

    Whereas women of all ages prefer slightly older sexual partners, men-regardless of their age-have a preference for women in their 20s. Earlier research has suggested that this difference between the sexes' age preferences is resolved according to women's preferences. This research has not, however, sufficiently considered that the age range of considered partners might change over the life span. Here we investigated the age limits (youngest and oldest) of considered and actual sex partners in a population-based sample of 2,655 adults (aged 18-50 years). Over the investigated age span, women reported a narrower age range than men and women tended to prefer slightly older men. We also show that men's age range widens as they get older: While they continue to consider sex with young women, men also consider sex with women their own age or older. Contrary to earlier suggestions, men's sexual activity thus reflects also their own age range, although their potential interest in younger women is not likely converted into sexual activity. Compared to homosexual men, bisexual and heterosexual men were more unlikely to convert young preferences into actual behavior, supporting female-choice theory.

  13. Membrane Automata with Priorities

    Institute of Scientific and Technical Information of China (English)

    Luděk Cienciala; Lucie Ciencialová

    2004-01-01

    In this paper the one-way P automata with priorities are introduced. Such automata are P systemshere the membranes are only allowed to consume objects from parent membranes, under the given conditions. The result of computation of these systems is the set of multiset sequences consumed by skin membrane intc the system. The rules associated in some order with each membrane cannot modify any objects, they can only move them through membrane. We show that P automata with priorities and two membranes can accept every recursively enumerated language.

  14. Variable velocity in solar external receivers

    Science.gov (United States)

    Rodríguez-Sánchez, M. R.; Sánchez-González, A.; Acosta-Iborra, A.; Santana, D.

    2017-06-01

    One of the major problems in solar external receivers is tube overheating, which accelerates the risk of receiver failure. It can be solved implementing receivers with high number of panels. However, it exponentially increases the pressure drop in the receiver and the parasitic power consumption of the Solar Power Tower (SPT), reducing the global efficiency of the SPT. A new concept of solar external receiver, named variable velocity receiver, is able to adapt their configuration to the different flux density distributions. A set of valves allows splitting in several independent panels those panels in which the wall temperature is over the limit. It increases the velocity of the heat transfer fluid (HTF) and its cooling capacity. This receiver does not only reduce the wall temperature of the tubes, but also simplifies the control of the heliostat field and allows to employ more efficient aiming strategies. In this study, it has been shown that variable velocity receiver presents high advantages with respect to traditional receiver. Nevertheless, more than two divisions per panels are not recommendable, due to the increment of the pressure drop over 70 bars. In the design point (12 h of the Spring Equinox), the use of a variable number of panels between 18 and 36 (two divisions per panel), in a SPT similar to Gemasolar, improves the power capacity of the SPT in 5.7%, with a pressure drop increment of 10 bars. Off-design, when the flux distribution is high and not symmetric (e.g. 10-11 h), the power generated by the variable velocity receiver is 18% higher than the generated by the traditional receiver, at these hours the pressure drop increases almost 20 bars.

  15. Externally Wetted Ionic Liquid Thruster

    Science.gov (United States)

    Lozano, P.; Martinez-Sanchez, M.; Lopez-Urdiales, J. M.

    2004-10-01

    This paper presents initial developments of an electric propulsion system based on ionic liquid ion sources (ILIS). Propellants are ionic liquids, which are organic salts with two important characteristics; they remain in the liquid state at room temperature and have negligible vapor pressure, thus allowing their use in vacuum. The working principles of ILIS are similar to those of liquid metal ion sources (LMIS), in which a Taylor cone is electrostatically formed at the tip of an externally wetted needle while ions are emitted directly from its apex. ILIS have the advantage of being able to produce negative ions that have similar masses than their positive counterparts with similar current levels. This opens up the possibility of achieving plume electrical neutrality without electron emitters. The possible multiplexing of these emitters is discussed in terms of achievable thrust density for applications other than micro-propulsion.

  16. External symmetry in general relativity

    CERN Document Server

    Cotaescu, I I

    2000-01-01

    We propose a generalization of the isometry transformations to the geometric context of the field theories with spin where the local frames are explicitly involved. We define the external symmetry transformations as isometries combined with suitable tetrad gauge transformations and we show that these form a group which is locally isomorphic with the isometry one. We point out that the symmetry transformations that leave invariant the equations of the fields with spin have generators with specific spin terms which represent new physical observables. The examples we present are the generators of the central symmetry and those of the maximal symmetries of the de Sitter and anti-de Sitter spacetimes derived in different tetrad gauge fixings. Pacs: 04.20.Cv, 04.62.+v, 11.30.-j

  17. External Cooling Coupled to Reduced Extremity Pressure Device

    Science.gov (United States)

    Kuznetz, Lawrence H.

    2011-01-01

    Although suited astronauts are currently cooled with a Liquid Cooled Ventilation Garment (LCVG), which can remove up to 85 percent of body heat, their effectiveness is limited because cooling must penetrate layers of skin, muscle, fat, bone, and tissue to reach the bloodstream, where its effect is prominent. Vasoconstriction further reduces the effectiveness by limiting arterial flow when exposed to cold (the frostbite response), resulting in a time constant on the order of 20 minutes from application to maximum effect. This delay can be crucial in severe exposure to hypo- or hyper-thermic conditions, compromising homeostasis. The purpose of this innovation is to provide a lightweight, effective means of delivering heat or cold from an external source directly to the bloodstream. The effectiveness of this ECCREP (External Cooling Coupled to Reduced Extremity Pressure) device is based on not having to penetrate layers of skin, muscle, fat, and tissue, thereby avoiding the thermal lag associated with their mass and heat capacity. This is accomplished by means of an outer boot operating at a slightly reduced pressure than the rest of the body, combined with an inner boot cooled or heated by an external source via water or chemicals. Heat transfer from the external source to the foot takes place by means of circulating water or flexible heat pipes.

  18. Isomeric Detergent Comparison for Membrane Protein Stability

    DEFF Research Database (Denmark)

    Cho, Kyung Ho; Hariharan, Parameswaran; Mortensen, Jonas S.;

    2016-01-01

    Membrane proteins encapsulated by detergent micelles are widely used for structural study. Because of their amphipathic property, detergents have the ability to maintain protein solubility and stability in an aqueous medium. However, conventional detergents have serious limitations in their scope...... and utility, particularly for eukaryotic membrane proteins and membrane protein complexes. Thus, a number of new agents have been devised; some have made significant contributions to membrane protein structural studies. However, few detergent design principles are available. In this study, we prepared meta...... and ortho isomers of the previously reported para-substituted xylene-linked maltoside amphiphiles (XMAs), along with alkyl chain-length variation. The isomeric XMAs were assessed with three membrane proteins, and the meta isomer with a C12 alkyl chain was most effective at maintaining solubility/stability...

  19. POLYETHERSULFONE COMPOSITE MEMBRANE BLENDED WITH CELLULOSE FIBRILS

    Directory of Open Access Journals (Sweden)

    Ping Qu

    2010-09-01

    Full Text Available Polyethersulfone (PES is a common material used for ultrafiltration (UF membranes, which has good chemical resistance, high mechanical properties, and wide temperature tolerances. The hydrophobic property of the PES membrane seriously limits its application. Cellulose fibrils are composed of micro-sized and nano-sized elements, which have high hydrophilicity, strength, and biodegradation. A composite membrane was prepared by the phase inversion induced by an immersion process. The characteristics of the composite membrane were investigated with Fourier transform infrared spectroscopy (FTIR, X-ray diffraction (XRD, thermogravimetric analysis (TGA, and atomic force microscopy (AFM. The pure water flux of the composite membrane increased dramatically with the increase of cellulose firbils. Mean pore size and porosity were significantly increased. Both mechanical properties and hydrophilicity were enhanced due to the addition of the cellulose firbils.

  20. Carbon Nanotube Membranes: Carbon Nanotube Membranes for Energy-Efficient Carbon Sequestration

    Energy Technology Data Exchange (ETDEWEB)

    None

    2010-03-01

    Broad Funding Opportunity Announcement Project: Porifera is developing carbon nanotube membranes that allow more efficient removal of CO2 from coal plant exhaust. Most of today’s carbon capture methods use chemical solvents, but capture methods that use membranes to draw CO2 out of exhaust gas are potentially more efficient and cost effective. Traditionally, membranes are limited by the rate at which they allow gas to flow through them and the amount of CO2 they can attract from the gas. Smooth support pores and the unique structure of Porifera’s carbon nanotube membranes allows them to be more permeable than other polymeric membranes, yet still selective enough for CO2 removal. This approach could overcome the barriers facing membrane-based approaches for capturing CO2 from coal plant exhausts.

  1. Membrane microdomains: from seeing to understanding

    Directory of Open Access Journals (Sweden)

    Binh-An eTruong Quang

    2014-02-01

    Full Text Available The plasma membrane is a composite material, which forms a semi-permeable barrier and an interface for communication between the intracellular and extracellular environments. While the existence of membrane microdomains with nanoscale organization has been proved by the application of numerous biochemical and physical methods, direct observation of these heterogeneities using optical microscopy has remained challenging for decades, partly due to the optical diffraction limit, which restricts the resolution to approximately 200 nm. During the past years, new optical methods which circumvent this fundamental limit have emerged. Not only do these techniques allow direct visualization, but also quantitative characterization of nanoscopic structures. We discuss how these emerging optical methods have refined our knowledge of membrane microdomains and how they may shed light on the basic principles of the mesoscopic membrane organization.

  2. Lipids and membrane lateral organization

    Directory of Open Access Journals (Sweden)

    Sandro eSonnino

    2010-11-01

    Full Text Available Shortly after the elucidation of the very basic structure and properties of cellular membranes, it became evident that cellular membranes are highly organized structures with multiple and multi-dimensional levels of order. Very early observations suggested that the lipid components of biological membranes might be active players in the creations of these levels of order. In the late 80’s, several different and diverse experimental pieces of evidence coalesced together giving rise to the lipid raft hypothesis. Lipid rafts became enormously (and, in the opinion of these authors, sometimes acritically popular, surprisingly not just within the lipidologist community (who is supposed to be naturally sensitive to the fascination of lipid rafts. Today, a PubMed search using the key word lipid rafts returned a list of 3767 papers, including 690 reviews (as a term of comparison, searching over the same time span for a very hot lipid-related key word, ceramide returned 6187 hits with 799 reviews, and a tremendous number of different cellular functions have been described as lipid raft-dependent. However, a clear consensus definition of lipid raft has been proposed only in recent times, and the basic properties, the ruling forces, and even the existence of lipid rafts in living cells have been recently matter of intense debate. The scenario that is gradually emerging from the controversies elicited by the lipid raft hypothesis emphasize multiple roles for membrane lipids in determining membrane order, that encompasses their tendency to phase separation but are clearly not limited to this. In this review, we would like to re-focus the attention of the readers on the importance of lipids in organizing the fine structure of cellular membranes.

  3. Membrane Tolerance to Ethanol is Rapidly Lost after Withdrawal: A Model for Studies of Membrane Adaptation

    Science.gov (United States)

    Taraschi, Theodore F.; Ellingson, John S.; Wu, Alice; Zimmerman, Robert; Rubin, Emanuel

    1986-06-01

    The structural properties of liver microsomes and erythrocytes obtained from rats that had been chronically administered ethanol were examined by electron spin resonance (ESR) following ethanol withdrawal for 1-10 days. Membranes obtained from control animals exhibited considerable molecular disordering upon the addition of ethanol in vitro (50-100 mM). Conversely, microsomal and erythrocyte membranes from alcoholic animals were resistant to this disordering by ethanol (membrane tolerance). These membrane properties were also apparent in lipid bilayers comprised of either total lipids or phospholipids isolated from the control and alcoholic animals. While several weeks of ethanol administration were required for both erythrocytes and microsomes to develop membrane tolerance, erythrocytes from alcoholic animals were disordered by ethanol in vitro after the animals had been withdrawn from ethanol for only 1 day. The same rapid loss of tolerance was observed in microsomes after 2 days of withdrawal. The same time course for the loss of tolerance was observed in lipid bilayers prepared from the total lipid and phospholipid extracts. No significant differences in the cholesterol/phospholipid ratio were observed between the microsomal or erythrocyte membranes isolated before and after withdrawal. Thus, alterations in the microsomal and erythrocyte phospholipids, and not cholesterol content, were responsible for conveying membrane tolerance. Membrane structural properties can be rapidly adjusted in a mammalian system in response to the withdrawal of the external membrane perturbant ethanol. The withdrawal model, which begins with established membrane tolerance and leads to rapid and complete loss of tolerance, provides a model to analyze the compositional changes responsible for this tolerance to disordering by ethanol.

  4. Composite zeolite membranes

    Science.gov (United States)

    Nenoff, Tina M.; Thoma, Steven G.; Ashley, Carol S.; Reed, Scott T.

    2002-01-01

    A new class of composite zeolite membranes and synthesis techniques therefor has been invented. These membranes are essentially defect-free, and exhibit large levels of transmembrane flux and of chemical and isotopic selectivity.

  5. Oxygen transport membrane

    DEFF Research Database (Denmark)

    2015-01-01

    The present invention relates to a novel composite oxygen transport membrane as well as its preparation and uses thereof.......The present invention relates to a novel composite oxygen transport membrane as well as its preparation and uses thereof....

  6. Hybrid adsorptive membrane reactor

    Science.gov (United States)

    Tsotsis, Theodore T. (Inventor); Sahimi, Muhammad (Inventor); Fayyaz-Najafi, Babak (Inventor); Harale, Aadesh (Inventor); Park, Byoung-Gi (Inventor); Liu, Paul K. T. (Inventor)

    2011-01-01

    A hybrid adsorbent-membrane reactor in which the chemical reaction, membrane separation, and product adsorption are coupled. Also disclosed are a dual-reactor apparatus and a process using the reactor or the apparatus.

  7. Solvent resistant nanofiltration membranes

    OpenAIRE

    Dutczak, S.M.

    2011-01-01

    This thesis describes preparation and characterization of membranes for organic solvent filtration (OSF). The main aim was developing membranes for solvent resistant nanofiltration (SRNF) with molecular weight cut-off below 500 g mol-1.

  8. Transmembrane Signalling: Membrane messengers

    Science.gov (United States)

    Cockroft, Scott L.

    2017-05-01

    Life has evolved elaborate means of communicating essential chemical information across cell membranes. Inspired by biology, two new artificial mechanisms have now been developed that use synthetic messenger molecules to relay chemical signals into or across lipid membranes.

  9. Ionene membrane battery separator

    Science.gov (United States)

    Moacanin, J.; Tom, H. Y.

    1969-01-01

    Ionic transport characteristics of ionenes, insoluble membranes from soluble polyelectrolyte compositions, are studied for possible application in a battery separator. Effectiveness of the thin film of separator membrane essentially determines battery lifetime.

  10. Hybrid adsorptive membrane reactor

    Science.gov (United States)

    Tsotsis, Theodore T.; Sahimi, Muhammad; Fayyaz-Najafi, Babak; Harale, Aadesh; Park, Byoung-Gi; Liu, Paul K. T.

    2011-03-01

    A hybrid adsorbent-membrane reactor in which the chemical reaction, membrane separation, and product adsorption are coupled. Also disclosed are a dual-reactor apparatus and a process using the reactor or the apparatus.

  11. 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

  12. 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

  13. Membrane-less microfiltration using inertial microfluidics

    OpenAIRE

    Majid Ebrahimi Warkiani; Andy Kah Ping Tay; Guofeng Guan; Jongyoon Han

    2015-01-01

    Microfiltration is a ubiquitous and often crucial part of many industrial processes, including biopharmaceutical manufacturing. Yet, all existing filtration systems suffer from the issue of membrane clogging, which fundamentally limits the efficiency and reliability of the filtration process. Herein, we report the development of a membrane-less microfiltration system by massively parallelizing inertial microfluidics to achieve a macroscopic volume processing rates (~ 500 mL/min). We demonstra...

  14. New membrane structures with proton conducting properties

    DEFF Research Database (Denmark)

    Nørgaard, Casper Frydendal

    Perfluorosulfonic acid membranes (e.g. Nafion®) are the most widely applied electrolytes in Polymer Electrolyte Membrane Fuel Cells (PEMFCs) because of their good chemical stability, mechanical properties and high proton conductivity, when well hydrated. The upper limit of operating temperature...... [1, 2, 3]. Improved fuel cell performance from incorporation of hygroscopic oxides or solid proton conductors (e.g. zirconium phosphates) has been reported. The poster exhibits upcoming work in the field of composite electrolyte membranes at the University of Southern Denmark, combining radiation...

  15. Financial Openness and External Sector Management: The Indian Experiences

    OpenAIRE

    U Arabi

    2005-01-01

    The financial sector of an economy, comprising institutions, markets and instruments, is multi-dimensional in nature with both domestic and external facets. The broad contours of financial liberalization approach include, viz., (i) withdrawal of credit controls and excessively high reserve requirements; (ii) interest rate deregulation; (iii) privatization; (iv) deregulation and development of markets; (v) lowering of entry barriers, limits on participation of foreign banks, and restrictions o...

  16. Membrane contactor applications

    NARCIS (Netherlands)

    Klaassen, R.; Feron, P.H.M.; Jansen, A.

    2008-01-01

    In a membrane contactor the membrane separation is completely integrated with an extraction or absorption operation in order to exploit the benefits of both technologies fully. Membrane contactor applications that have been developed can be found in both water and gas treatment. Several recently dev

  17. On "spinning" membrane models

    NARCIS (Netherlands)

    Bergshoeff, E.; Sezgin, E.; Townsend, P.K.

    1988-01-01

    Several alternative actions for a bosonic membrane have recently been proposed. We show that a linearly realized locally world-volume-supersymmetric (spinning membrane) extension of any of these actions implies an analogous extension of the standard Dirac membrane action. We further show that a

  18. Ion Transport through Diffusion Layer Controlled by Charge Mosaic Membrane

    Directory of Open Access Journals (Sweden)

    Akira Yamauchi

    2012-01-01

    Full Text Available The kinetic transport behaviors in near interface of the membranes were studied using commercial anion and cation exchange membrane and charge mosaic membrane. Current-voltage curve gave the limiting current density that indicates the ceiling of conventional flux. From chronopotentiometry above the limiting current density, the transition time was estimated. The thickness of boundary layer was derived with conjunction with the conventional limiting current density and the transition time from steady state flux. On the other hand, the charge mosaic membrane was introduced in order to examine the ion transport on the membrane surface in detail. The concentration profile was discussed by the kinetic transport number with regard to the water dissociation (splitting on the membrane surface.

  19. External Cylindrical Nozzle with Controlled Vacuum

    Directory of Open Access Journals (Sweden)

    V. N. Pil'gunov

    2015-01-01

    Full Text Available There is a developed design of the external cylindrical nozzle with a vacuum camera. The paper studies the nozzle controllability of flow rate via regulated connection of the evacuated chamber to the atmosphere through an air throttle. Working capacity of the nozzle with inlet round or triangular orifice are researched. The gap is provided in the nozzle design between the external wall of the inlet orifice and the end face of the straight case in the nozzle case. The presented mathematical model of the nozzle with the evacuated chamber allows us to estimate the expected vacuum amount in the compressed section of a stream and maximum permissible absolute pressure at the inlet orifice. The paper gives experimental characteristics of the fluid flow process through the nozzle for different values of internal diameter of a straight case and an extent of its end face remoteness from an external wall of the inlet orifice. It estimates how geometry of nozzle constructive elements influences on the volume flow rate. It is established that the nozzle capacity significantly depends on the shape of inlet orifice. Triangular orifice nozzles steadily work in the mode of completely filled flow area of the straight case at much more amounts of the limit pressure of the flow. Vacuum depth in the evacuated chamber also depends on the shape of inlet orifice: the greatest vacuum is reached in a nozzle with the triangular orifice which 1.5 times exceeds the greatest vacuum with the round orifice. Possibility to control nozzle capacity through the regulated connection of the evacuated chamber to the atmosphere was experimentally estimated, thus depth of flow rate regulation of the nozzle with a triangular orifice was 45% in comparison with 10% regulation depth of the nozzle with a round orifice. Depth of regulation calculated by a mathematical model appeared to be much more. The paper presents experimental dependences of the flow coefficients of nozzle input orifice

  20. Targeting Membrane Lipid a Potential Cancer Cure?

    Science.gov (United States)

    Tan, Loh Teng-Hern; Chan, Kok-Gan; Pusparajah, Priyia; Lee, Wai-Leng; Chuah, Lay-Hong; Khan, Tahir Mehmood; Lee, Learn-Han; Goh, Bey-Hing

    2017-01-01

    Cancer mortality and morbidity is projected to increase significantly over the next few decades. Current chemotherapeutic strategies have significant limitations, and there is great interest in seeking novel therapies which are capable of specifically targeting cancer cells. Given that fundamental differences exist between the cellular membranes of healthy cells and tumor cells, novel therapies based on targeting membrane lipids in cancer cells is a promising approach that deserves attention in the field of anticancer drug development. Phosphatidylethanolamine (PE), a lipid membrane component which exists only in the inner leaflet of cell membrane under normal circumstances, has increased surface representation on the outer membrane of tumor cells with disrupted membrane asymmetry. PE thus represents a potential chemotherapeutic target as the higher exposure of PE on the membrane surface of cancer cells. This feature as well as a high degree of expression of PE on endothelial cells in tumor vasculature, makes PE an attractive molecular target for future cancer interventions. There have already been several small molecules and membrane-active peptides identified which bind specifically to the PE molecules on the cancer cell membrane, subsequently inducing membrane disruption leading to cell lysis. This approach opens up a new front in the battle against cancer, and is of particular interest as it may be a strategy that may be prove effective against tumors that respond poorly to current chemotherapeutic agents. We aim to highlight the evidence suggesting that PE is a strong candidate to be explored as a potential molecular target for membrane targeted novel anticancer therapy. PMID:28167913

  1. Improving low-performing schools through external assistance: Lessons from Chicago and California.

    Directory of Open Access Journals (Sweden)

    Kara S. Finnigan

    2009-04-01

    Full Text Available This article describes the design and implementation of external support to low-performing schools using data from Chicago and California. Using the literature on external support, instructional capacity, and policy strength, the study gathered data from interviews, observations, document review, and surveys. The findings suggest that the model of assistance employed in both Chicago and California was inadequate to the task. While the policies examined demonstrate recognition that low-performing schools need additional capacity if they are to substantially improve student outcomes, external support providers used limited and haphazard approaches, and as a result, the support component had little influence on teaching and learning. In addition, because the external supports relied on a market-like support structure with few other mechanisms to ensure quality, and because there was limited quantity (intensity of support, the benefit that external assistance might otherwise have provided was limited. This was particularly problematic for the lowest capacity schools, many of which experienced limited change despite increased educator effort and involvement of external providers. In essence, external assistance through these school accountability policies did little to improve educator and organizational performance.

  2. Kinetics and Thermodynamics of Membrane Protein Folding

    Directory of Open Access Journals (Sweden)

    Ernesto A. Roman

    2014-03-01

    Full Text Available Understanding protein folding has been one of the great challenges in biochemistry and molecular biophysics. Over the past 50 years, many thermodynamic and kinetic studies have been performed addressing the stability of globular proteins. In comparison, advances in the membrane protein folding field lag far behind. Although membrane proteins constitute about a third of the proteins encoded in known genomes, stability studies on membrane proteins have been impaired due to experimental limitations. Furthermore, no systematic experimental strategies are available for folding these biomolecules in vitro. Common denaturing agents such as chaotropes usually do not work on helical membrane proteins, and ionic detergents have been successful denaturants only in few cases. Refolding a membrane protein seems to be a craftsman work, which is relatively straightforward for transmembrane β-barrel proteins but challenging for α-helical membrane proteins. Additional complexities emerge in multidomain membrane proteins, data interpretation being one of the most critical. In this review, we will describe some recent efforts in understanding the folding mechanism of membrane proteins that have been reversibly refolded allowing both thermodynamic and kinetic analysis. This information will be discussed in the context of current paradigms in the protein folding field.

  3. Novel membrane for guided bone regeneration.

    Science.gov (United States)

    Pirhonen, E M; Pohjonen, T H; Weber, F E

    2006-09-01

    Membranes have been clinically used for guided tissue and bone regeneration for decades, but their use in every day clinical practice is rather limited. We developed a biodegradable membrane (InionGTR) composed of polylactide, polyglycolide and trimethylene carbonate aiming to improve the properties of membrane. Before application the membrane is treated with N-methyl-pyrrolidone (NMP) to achieve a rubber like consistency, to allow easy handling and manageability in the clinical setting. After placing the membrane NMP diffuses out from the polymer phase into the water phase. The loss of NMP in the polymer stiffens the membrane up and allows space maintenance in the defect area. In addition the influx and efflux of NMP creates a porous surface on the membrane leading to an improved integration of tissues into the porous surface layers of the InionGTR membrane. Therefore, the use of NMP improves the handling in the clinical setting, and allows tissue integration and space maintenance, both important for the outcome of the treatment.

  4. Osmotically driven drug delivery through remote-controlled magnetic nanocomposite membranes

    KAUST Repository

    Zaher, A.

    2015-09-29

    Implantable drug delivery systems can provide long-term reliability, controllability, and biocompatibility, and have been used in many applications, including cancer pain and non-malignant pain treatment. However, many of the available systems are limited to zero-order, inconsistent, or single burst event drug release. To address these limitations, we demonstrate prototypes of a remotely operated drug delivery device that offers controllability of drug release profiles, using osmotic pumping as a pressure source and magnetically triggered membranes as switchable on-demand valves. The membranes are made of either ethyl cellulose, or the proposed stronger cellulose acetate polymer, mixed with thermosensitive poly(N-isopropylacrylamide) hydrogel and superparamagnetic iron oxide particles. The prototype devices\\' drug diffusion rates are on the order of 0.5–2 μg/h for higher release rate designs, and 12–40 ng/h for lower release rates, with maximum release ratios of 4.2 and 3.2, respectively. The devices exhibit increased drug delivery rates with higher osmotic pumping rates or with magnetically increased membrane porosity. Furthermore, by vapor deposition of a cyanoacrylate layer, a drastic reduction of the drug delivery rate from micrograms down to tens of nanograms per hour is achieved. By utilizing magnetic membranes as the valve-control mechanism, triggered remotely by means of induction heating, the demonstrated drug delivery devices benefit from having the power source external to the system, eliminating the need for a battery. These designs multiply the potential approaches towards increasing the on-demand controllability and customizability of drug delivery profiles in the expanding field of implantable drug delivery systems, with the future possibility of remotely controlling the pressure source.

  5. Tracking membrane protein association in model membranes.

    Directory of Open Access Journals (Sweden)

    Myriam Reffay

    Full Text Available Membrane proteins are essential in the exchange processes of cells. In spite of great breakthrough in soluble proteins studies, membrane proteins structures, functions and interactions are still a challenge because of the difficulties related to their hydrophobic properties. Most of the experiments are performed with detergent-solubilized membrane proteins. However widely used micellar systems are far from the biological two-dimensions membrane. The development of new biomimetic membrane systems is fundamental to tackle this issue.We present an original approach that combines the Fluorescence Recovery After fringe Pattern Photobleaching technique and the use of a versatile sponge phase that makes it possible to extract crucial informations about interactions between membrane proteins embedded in the bilayers of a sponge phase. The clear advantage lies in the ability to adjust at will the spacing between two adjacent bilayers. When the membranes are far apart, the only possible interactions occur laterally between proteins embedded within the same bilayer, whereas when membranes get closer to each other, interactions between proteins embedded in facing membranes may occur as well.After validating our approach on the streptavidin-biotinylated peptide complex, we study the interactions between two membrane proteins, MexA and OprM, from a Pseudomonas aeruginosa efflux pump. The mode of interaction, the size of the protein complex and its potential stoichiometry are determined. In particular, we demonstrate that: MexA is effectively embedded in the bilayer; MexA and OprM do not interact laterally but can form a complex if they are embedded in opposite bilayers; the population of bound proteins is at its maximum for bilayers separated by a distance of about 200 A, which is the periplasmic thickness of Pseudomonas aeruginosa. We also show that the MexA-OprM association is enhanced when the position and orientation of the protein is restricted by the

  6. Proteolysis at the plasma membrane of tobacco roots: biochemical evidence and possible roles.

    Science.gov (United States)

    Eick, Manuela; Stöhr, Christine

    2009-01-01

    Plasma membrane-associated proteases (pm-proteases) exist principally in roots of Nicotiana tabacum cv. Samsun, whereas in plasma membrane (pm) vesicles prepared from leaves, protease activity was at the detection limit. Biochemical characterisation revealed a high diversity of particular hydrophobic pm-proteases indicating multiple functions in root tissue. One proportion of chromatographically separated proteases was split up by non-reducing SDS-PAGE in 8-12 single polypeptides, dependent on plant nitrogen nutrition. The active polypeptides could be grouped in those that were (i) inhibited, (ii) stimulated and (iii) independent of bivalent cations. Although, the total specific protease activity of various pm vesicles was almost identical, the composition and activity of individual polypeptides was dependent on nitrogen supply of the plants. Particularly, nitrogen deficiency stimulated the activity of high molecular mass proteases (125 kDa-97 kDa), whereas sufficient nitrate supply enhanced proteolytic activity of 90 kDa, 83 kDa and 65 kDa polypeptides. Endogenous proteolysis within pm vesicles suggested that at least partly protease substrates are localised within the same membrane. A comparison of polypeptides originated from proteolysis of pm vesicles and those exudated by roots into the external medium points to a role of root pm-proteases in the specific release of polypeptides into the rhizosphere.

  7. Chinese external assistance to Rwanda

    African Journals Online (AJOL)

    User

    of China's assistance, describes the evolution of China's assistance to and cooperation ..... Assessing historic aid flows to Rwanda is equally challenging due to limitations ..... Development and Poverty Reduction Strategy in planning for Rwanda's .... http://www.bnr.rw/docs/publicnotices/report2008.pdf [Accessed 8 August.

  8. Thin-Film Composite Pressure Retarded Osmosis Membranes for Sustainable Power Generation from Salinity Gradients

    KAUST Repository

    Yip, Ngai Yin

    2011-05-15

    Pressure retarded osmosis has the potential to produce renewable energy from natural salinity gradients. This work presents the fabrication of thin-film composite membranes customized for high performance in pressure retarded osmosis. We also present the development of a theoretical model to predict the water flux in pressure retarded osmosis, from which we can predict the power density that can be achieved by a membrane. The model is the first to incorporate external concentration polarization, a performance limiting phenomenon that becomes significant for high-performance membranes. The fabricated membranes consist of a selective polyamide layer formed by interfacial polymerization on top of a polysulfone support layer made by phase separation. The highly porous support layer (structural parameter S = 349 μm), which minimizes internal concentration polarization, allows the transport properties of the active layer to be customized to enhance PRO performance. It is shown that a hand-cast membrane that balances permeability and selectivity (A = 5.81 L m-2 h-1 bar-1, B = 0.88 L m-2 h-1) is projected to achieve the highest potential peak power density of 10.0 W/m2 for a river water feed solution and seawater draw solution. The outstanding performance of this membrane is attributed to the high water permeability of the active layer, coupled with a moderate salt permeability and the ability of the support layer to suppress the undesirable accumulation of leaked salt in the porous support. Membranes with greater selectivity (i.e., lower salt permeability, B = 0.16 L m-2 h-1) suffered from a lower water permeability (A = 1.74 L m-2 h-1 bar-1) and would yield a lower peak power density of 6.1 W/m2, while membranes with a higher permeability and lower selectivity (A = 7.55 L m-2 h-1 bar-1, B = 5.45 L m-2 h-1) performed poorly due to severe reverse salt permeation, resulting in a similar projected peak power density of 6.1 W/m2. © 2011 American Chemical Society.

  9. Separation membrane development

    Energy Technology Data Exchange (ETDEWEB)

    Lee, M.W. [Savannah River Technology Center, Aiken, SC (United States)

    1998-08-01

    A ceramic membrane has been developed to separate hydrogen from other gases. The method used is a sol-gel process. A thin layer of dense ceramic material is coated on a coarse ceramic filter substrate. The pore size distribution in the thin layer is controlled by a densification of the coating materials by heat treatment. The membrane has been tested by permeation measurement of the hydrogen and other gases. Selectivity of the membrane has been achieved to separate hydrogen from carbon monoxide. The permeation rate of hydrogen through the ceramic membrane was about 20 times larger than Pd-Ag membrane.

  10. Mechanical reliability of geometrically imperfect tubular oxygen transport membranes

    DEFF Research Database (Denmark)

    Kwok, Kawai; Frandsen, Henrik Lund; Søgaard, Martin

    2014-01-01

    operation. This paper investigates numerically the failure risk of tubular oxygen transport membranes under industrial operating conditions using finite element modeling and Weibull strength analysis. The effects of component manufacturing defects on fracture probability are elucidated by explicit modeling...... of imperfections in the tubular membrane geometry. A supported membrane made of dense and porous Zr-doped-BSCF is studied as an illustrative example. It is shown that stresses induced by oxygen stoichiometry gradients relax over time due to creep and external pressure is the dominating source of stress in the long...... term. Therefore, creep has no adverse effect for geometrically perfect membranes. For geometrically imperfect membranes, curl and eccentricity are found to have insignificant influence on fracture risk while ovality is identified as the most critical geometric imperfection. Under the influence...

  11. ANALYSIS OF EXTERNAL FACTORS AFFECTING THE PRICING

    Directory of Open Access Journals (Sweden)

    Irina A. Kiseleva

    2013-01-01

    Full Text Available The external factors influencing the process of formation of tariffs of commercial services are considered in the article. External environment is known to be very diverse and changeable. Currently, pricing has become one of the key processes of strategic development of a company. Pricing in the service sector, in turn, is highly susceptible to changes in the external environment. Its components directly or indirectly affect the market of services, changing it adopted economic processes. As a rule, firms providing services can’t influence the changes in external factors. However, the service market is very flexible, which enables businesses to reshape pricing strategy, to adapt it to the new environment.

  12. Molecular machines open cell membranes

    Science.gov (United States)

    García-López, Víctor; Chen, Fang; Nilewski, Lizanne G.; Duret, Guillaume; Aliyan, Amir; Kolomeisky, Anatoly B.; Robinson, Jacob T.; Wang, Gufeng; Pal, Robert; Tour, James M.

    2017-08-01

    Beyond the more common chemical delivery strategies, several physical techniques are used to open the lipid bilayers of cellular membranes. These include using electric and magnetic fields, temperature, ultrasound or light to introduce compounds into cells, to release molecular species from cells or to selectively induce programmed cell death (apoptosis) or uncontrolled cell death (necrosis). More recently, molecular motors and switches that can change their conformation in a controlled manner in response to external stimuli have been used to produce mechanical actions on tissue for biomedical applications. Here we show that molecular machines can drill through cellular bilayers using their molecular-scale actuation, specifically nanomechanical action. Upon physical adsorption of the molecular motors onto lipid bilayers and subsequent activation of the motors using ultraviolet light, holes are drilled in the cell membranes. We designed molecular motors and complementary experimental protocols that use nanomechanical action to induce the diffusion of chemical species out of synthetic vesicles, to enhance the diffusion of traceable molecular machines into and within live cells, to induce necrosis and to introduce chemical species into live cells. We also show that, by using molecular machines that bear short peptide addends, nanomechanical action can selectively target specific cell-surface recognition sites. Beyond the in vitro applications demonstrated here, we expect that molecular machines could also be used in vivo, especially as their design progresses to allow two-photon, near-infrared and radio-frequency activation.

  13. External Beam Radiation in Differentiated Thyroid Carcinoma

    Directory of Open Access Journals (Sweden)

    Salem Billan

    2016-01-01

    Full Text Available The treatment of differentiated thyroid carcinoma (DTC is surgery followed in some cases by adjuvant treatment, mostly with radioactive iodine (RAI. External beam radiotherapy (EBRT is less common and not a well-established treatment modality in DTC. The risk of recurrence depends on three major prognostic factors: extra-thyroid extension, patient’s age, and tumor with reduced iodine uptake. Increased risk for recurrence is a major factor in the decision whether to treat the patient with EBRT. Data about the use of EBRT in DTC are limited to small retrospective studies. Most series have demonstrated an increase in loco-regional control. The risk/benefit from giving EBRT requires careful patient selection. Different scoring systems have been proposed by different investigators and centers. The authors encourage clinicians treating DTC to become familiarized with those scoring systems and to use them in the management of different cases. The irradiated volume should include areas of risk for microscopic disease. Determining those areas in each case can be difficult and requires detailed knowledge of the surgery and pathological results, and also understanding of the disease-spreading pattern. Treatment with EBRT in DTC can be beneficial, and data support the use of EBRT in high-risk patients. Randomized controlled trials are needed for better confirmation of the role of EBRT.

  14. Holographic fermions in external magnetic fields

    CERN Document Server

    Gubankova, E; Cubrovic, M; Schalm, K; Schijven, P; Zaanen, J

    2011-01-01

    We study the Fermi level structure of 2+1-dimensional strongly interacting electron systems in external magnetic field using the AdS/CFT correspondence. The gravity dual of a finite density fermion system is a Dirac field in the background of the dyonic AdS-Reissner-Nordstrom black hole. In the probe limit the magnetic system can be reduced to the non-magnetic one, with Landau-quantized momenta and rescaled thermodynamical variables. We find that at strong enough magnetic fields, the Fermi surface vanishes and the quasiparticle is lost either through a crossover to conformal regime or through a phase transition to an unstable Fermi surface. In the latter case, the vanishing Fermi velocity at the critical magnetic field triggers the non-Fermi liquid regime with unstable quasiparticles and a change in transport properties of the system. We associate it with a metal-"strange metal" phase transition. Next we compute compute the DC Hall and longitudinal conductivities using the gravity-dressed fermion propagators....

  15. Resultado funcional e índice macular em portadores de buraco macular submetidos à cirurgia com remoção da membrana limitante interna Functional outcome and macular index in macular hole patients who underwent surgery with internal limiting membrane removal

    Directory of Open Access Journals (Sweden)

    José Ricardo Diniz

    2008-04-01

    Full Text Available OBJETIVOS: Avaliar o resultado funcional e o índice macular dos portadores de buraco macular submetidos à cirurgia com remoção da membrana limitante interna. MÉTODOS: Quinze olhos de 15 pacientes com buraco macular estágios 2, 3 e 4 foram incluídos no estudo. Todos foram submetidos à cirurgia de buraco macular convencional com remoção da membrana limitante interna corada pelo azul de tripan. Melhor acuidade visual com correção e cortes transversais medidos por tomografia de coerência óptica (OCT foram avaliados no pré- e pós-operatório. O índice macular (razão entre a altura e base do buraco macular foi calculado e correlacionado com o diâmetro mínimo do buraco macular e o ganho de acuidade visual pós-operatória. RESULTADOS: Obteve-se fechamento do buraco macular em todos pacientes operados. Em 86,7%, houve ganho de pelo menos três linhas de visão. O índice macular demonstrou correlação negativa significante com o diâmetro mínimo (r=0,811. Não foi observada correlação significante entre o índice macular e o ganho de acuidade visual pós-operatória (r=0,351. CONCLUSÃO: Os resultados funcionais na cirurgia do buraco macular com remoção da membrana limitante interna foram bons neste grupo de pacientes. O índice macular demonstrou ser compatível com a configuração espacial do buraco macular, porém não foi preditor de resultados visuais.PURPOSE: To evaluate the functional outcome and macular index in patients with macular hole who underwent surgery with internal limiting membrane removal. METHODS: Fifteen eyes of 15 patients with idiopathic macular hole stages 2, 3 or 4 were enrolled in this study. All patients underwent conventional macular hole surgery with trypan blue staining to remove the internal limiting membrane. The best-corrected visual acuity and cross-sectional images of macular hole measured by optical coherence tomography (OCT were evaluated pre- and postoperatively. The macular hole index

  16. Supported ionic liquid membrane in membrane reactor

    Science.gov (United States)

    Makertihartha, I. G. B. N.; Zunita, M.; Dharmawijaya, P. T.; Wenten, I. G.

    2017-01-01

    Membrane reactor is a device that integrates membrane based separation and (catalytic) chemical reaction vessel in a single device. Ionic liquids, considered to be a relatively recent magical chemical due to their unique properties, have a large variety of applications in all areas of chemical industries. Moreover, the ionic liquid can be used as membrane separation layer and/or catalytically active site. This paper will review utilization of ionic liquid in membrane reactor related applications especially Fischer-Tropsch, hydrogenation, and dehydrogenation reaction. This paper also reviews about the capability of ionic liquid in equilibrium reaction that produces CO2 product so that the reaction will move towards the product. Water gas shift reaction in ammonia production also direct Dimethyl Ether (DME) synthesis that produces CO2 product will be discussed. Based on a review of numerous articles on supported ionic liquid membrane (SILM) indicate that ionic liquids have the potential to support the process of chemical reaction and separation in a membrane reactor.

  17. Application of dynamic membranes in anaerobic membranes in anaerobic membrane bioreactor systems

    NARCIS (Netherlands)

    Erşahin, M.E.

    2015-01-01

    Anaerobic membrane bioreactors (AnMBRs) physically ensure biomass retention by the application of a membrane filtration process. With growing application experiences from aerobic membrane bioreactors (MBRs), the combination of membrane and anaerobic processes has received much attention and become

  18. Counter-current membrane reactor for WGS process: Membrane design

    Energy Technology Data Exchange (ETDEWEB)

    Piemonte, Vincenzo; Favetta, Barbara [Department of Chemical Engineering Materials and Environment, University of Rome ' ' La Sapienza' ' , via Eudossiana 18, 00184 Rome (Italy); De Falco, Marcello [Faculty of Engineering, University Campus Bio-Medico of Rome, via Alvaro del Portillo 21, 00128 Rome (Italy); Basile, Angelo [CNR-ITM, c/o University of Calabria, Via Pietro Bucci, Cubo 17/C, 87030 Rende (CS) (Italy)

    2010-11-15

    Water gas shift (WGS) is a thermodynamically limited reaction which has to operate at low temperatures, reducing kinetics rate and increasing the amount of catalyst required to reach valuable CO conversions. It has been widely demonstrated that the integration of hydrogen selective membranes is a promising way to enhance WGS reactors performance: a Pd-based MR operated successfully overcoming the thermodynamic constraints of a traditional reactor thanks to the removal of hydrogen from reaction environment. In the first part of a MR, the H{sub 2} partial pressure starts from a minimum value since the reaction has not started. As a consequence, if the carrier gas in the permeation zone is sent in counter-current, which is the most efficient configuration, in the first reactor section the H{sub 2} partial pressure in reaction zone is low while in the permeation zone is high, potentially implying back permeation. This means a bad utilization of the first part of the membrane area and thus, a worsening of the MR performance with lower H{sub 2} recovery and lower CO conversion with respect to the case in which the whole selective surface is properly used. To avoid this problem different MR configurations were evaluated by a 1-D pseudo-homogeneous model, validated with WGS industrial data reported in scientific literature. It was demonstrated that the permeated H{sub 2} flow rate per membrane surface, i.e. the membrane flux, strongly improves if selective membrane is placed only in the second part of the reactor: in fact, if the membrane is placed at L{sub m}/L{sub tot} = 0.5, the membrane flux is 0.2 kmol/(m{sup 2}h) about, if it is placed along all reactor tube (L{sub m}/L{sub tot} = 1), flux is 0.05 kmol/(m{sup 2}h). The effect of the L/D reactor ratio and of the reactor wall temperature on the CO conversion were also assessed. (author)

  19. Electrode-analytical properties of polyvinylchloride membranes based on triple metal-polymeric complexes

    OpenAIRE

    Matorina, Katerina V.; Chmilenko, Tetyana S.; Chmilenko, Fedor O.

    2015-01-01

    The influence of the nature of the electrode-active substances (EAS), the composition of the external and internal solutions on the formation of the analytical signal of polyvinylchloride (PVC) membranes based on associates and triple metal-polymeric complexes (TMPC) was established. Dehumidification of synthesized membranes increases with the content of polyvinylpyrrolidone (PVP). The value of the swelling degree is more than two times greater for membranes, which contain as EAS TMPC, relati...

  20. 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.

  1. Preparation of artificial plasma membrane mimicking vesicles with lipid asymmetry.

    Directory of Open Access Journals (Sweden)

    Qingqing Lin

    Full Text Available Lipid asymmetry, the difference in lipid distribution across the lipid bilayer, is one of the most important features of eukaryotic cellular membranes. However, commonly used model membrane vesicles cannot provide control of lipid distribution between inner and outer leaflets. We recently developed methods to prepare asymmetric model membrane vesicles, but facile incorporation of a highly controlled level of cholesterol was not possible. In this study, using hydroxypropyl-α-cyclodextrin based lipid exchange, a simple method was devised to prepare large unilamellar model membrane vesicles that closely resemble mammalian plasma membranes in terms of their lipid composition and asymmetry (sphingomyelin (SM and/or phosphatidylcholine (PC outside/phosphatidylethanolamine (PE and phosphatidylserine (PS inside, and in which cholesterol content can be readily varied between 0 and 50 mol%. We call these model membranes "artificial plasma membrane mimicking" ("PMm" vesicles. Asymmetry was confirmed by both chemical labeling and measurement of the amount of externally-exposed anionic lipid. These vesicles should be superior and more realistic model membranes for studies of lipid-lipid and lipid-protein interaction in a lipid environment that resembles that of mammalian plasma membranes.

  2. Preparation of artificial plasma membrane mimicking vesicles with lipid asymmetry.

    Science.gov (United States)

    Lin, Qingqing; London, Erwin

    2014-01-01

    Lipid asymmetry, the difference in lipid distribution across the lipid bilayer, is one of the most important features of eukaryotic cellular membranes. However, commonly used model membrane vesicles cannot provide control of lipid distribution between inner and outer leaflets. We recently developed methods to prepare asymmetric model membrane vesicles, but facile incorporation of a highly controlled level of cholesterol was not possible. In this study, using hydroxypropyl-α-cyclodextrin based lipid exchange, a simple method was devised to prepare large unilamellar model membrane vesicles that closely resemble mammalian plasma membranes in terms of their lipid composition and asymmetry (sphingomyelin (SM) and/or phosphatidylcholine (PC) outside/phosphatidylethanolamine (PE) and phosphatidylserine (PS) inside), and in which cholesterol content can be readily varied between 0 and 50 mol%. We call these model membranes "artificial plasma membrane mimicking" ("PMm") vesicles. Asymmetry was confirmed by both chemical labeling and measurement of the amount of externally-exposed anionic lipid. These vesicles should be superior and more realistic model membranes for studies of lipid-lipid and lipid-protein interaction in a lipid environment that resembles that of mammalian plasma membranes.

  3. A novel In-situ Enzymatic Cleaning Method for Reducing Membrane Fouling in Membrane Bioreactors (MBRs

    Directory of Open Access Journals (Sweden)

    M. R. Bilad

    2016-05-01

    Full Text Available A novel in-situ enzymatic cleaning method was developed for fouling control in membrane bioreactors (MBRs. It is achieved by bringing the required enzymes near the membrane surface by pulling the enzymes to a magnetic membrane (MM surface by means of magnetic forces, exactly where the cleaning is required. To achieve this, the enzyme was coupled to a magnetic nanoparticle (MNP and the membrane it self was loaded with MNP. The magnetic activity was turned by means of an external permanent magnet. The effectiveness of concept was tested in a submerged membrane filtration using the model enzyme-substrate of Bacillus subitilis xylanase-arabinoxylan. The MM had almost similar properties compared to the unloaded ones, except for its well distributed MNPs. The enzyme was stable during coupling conditions and the presence of coupling could be detected using a high-performance anion-exchange chromatography (HPAEC analysis and Fourier transform infrared spectroscopy (FTIR. The system facilitated an in-situ enzymatic cleaning and could be effectively applied for control fouling in membrane bioreactors (MBRs.

  4. Hydrogen separation membranes annual report for FY 2010.

    Energy Technology Data Exchange (ETDEWEB)

    Balachandran, U.; Dorris, S. E; Emerson, J. E.; Lee, T. H.; Lu, Y.; Park, C. Y.; Picciolo, J. J. (Energy Systems)

    2011-03-14

    The objective of this work is to develop dense ceramic membranes for separating hydrogen from other gaseous components in a nongalvanic mode, i.e., without using an external power supply or electrical circuitry. The goal of this project is to develop dense hydrogen transport membranes (HTMs) that nongalvanically (i.e., without electrodes or external power supply) separate hydrogen from gas mixtures at commercially significant fluxes under industrially relevant operating conditions. These membranes will be used to separate hydrogen from gas mixtures such as the product streams from coal gasification, methane partial oxidation, and water-gas shift reactions. Potential ancillary uses of HTMs include dehydrogenation and olefin production, as well as hydrogen recovery in petroleum refineries and ammonia synthesis plants, the largest current users of deliberately produced hydrogen. This report describes the results from the development and testing of HTM materials during FY 2010.

  5. Ceramic membranes for high temperature hydrogen separation

    Energy Technology Data Exchange (ETDEWEB)

    Fain, D.E.; Roettger, G.E. [Oak Ridge K-25 Site, TN (United States)

    1996-08-01

    Ceramic gas separation membranes can provide very high separation factors if the pore size is sufficiently small to separate gas molecules by molecular sieving and if oversized pores are adequately limited. Ceramic membranes typically have some pores that are substantially larger than the mean pore size and that should be regarded as defects. To assess the effects of such defects on the performance of ceramic membranes, a simple mathematical model has been developed to describe flow through a gas separation membrane that has a primary mode of flow through very small pores but that has a secondary mode of flow through undesirably large pores. This model permits separation factors to be calculated for a specified gas pair as a function of the molecular weights and molecular diameters of the gases, the membrane pore diameter, and the diameter and number of defects. This model will be described, and key results from the model will be presented. The separation factors of the authors membranes continue to be determined using a permeance test system that measures flows of pure gases through a membrane at temperatures up to 275{degrees}C. A primary goal of this project for FY 1996 is to develop a mixed gas separation system for measuring the separation efficiency of membranes at higher temperatures. Performance criteria have been established for the planned mixed gas separation system and design of the system has been completed. The test system is designed to measure the separation efficiency of membranes at temperatures up to 600{degrees}C and pressures up to 100 psi by separating the constituents of a gas mixture containing hydrogen. The system will accommodate the authors typical experimental membrane that is tubular and has a diameter of about 9 mm and a length of about 23 cm. The design of the new test system and its expected performance will be discussed.

  6. Emulsification using microporous membranes

    Directory of Open Access Journals (Sweden)

    Goran T. Vladisavljević

    2011-10-01

    Full Text Available Membrane emulsification is a process of injecting a pure dispersed phase or pre-emulsion through a microporous membrane into the continuous phase. As a result of the immiscibility of the two phases, droplets of the dispersed phase are formed at the outlets of membrane pores. The droplets formed in the process are removed from the membrane surface by applying cross-flow or stirring of the continuous phase or using a dynamic (rotating or vibrating membrane. The most commonly used membrane for emulsification is the Shirasu Porous Glass (SPG membrane, fabricated through spinodal decomposition in a melt consisting of Japanese volcanic ash (Shirasu, boric acid and calcium carbonate. Microsieve membranes are increasingly popular as an alternative to highly tortuous glass and ceramic membranes. Microsieves are usually fabricated from nickel by photolithography and electroplating or they can be manufactured from silicon nitride via Reactive Ion Etching (RIE. An advantage of microsieves compared to the SPG membrane is in much higher transmembrane fluxes and higher tolerance to fouling by the emulsion ingredients due to the existence of short, straight through pores. Unlike conventional emulsification devices such as high-pressure valve homogenisers and rotor-stator devices, membrane emulsification devices permit a precise control over the mean pore size over a wide range and during the process insignificant amount of energy is dissipated as heat. The drop size is primarily determined by the pore size, but it depends also on other parameters, such as membrane wettability, emulsion formulation, shear stress on the membrane surface, transmembrane pressure, etc.

  7. Preparation of Stable Pt-Clay Nanocatalysts for Self-humidifying Proton Exchange Membrane Fuel Cells

    DEFF Research Database (Denmark)

    Zhang, Wenjing

    ultrasonication and a rigorous mechanical agitation of Ptclay in the Nafion solution during the membrane casting process. Planar and hygroscopic clay reduced fuel crossover and balanced the water content. In situ water production for humidification of the dry membranes without any external humidification......One of the critical challenges in making proton exchange membrane (PEM) fuel cells commercially viable is the inability of Nafion (the most used PEM) to conduct protons at low water content level. Both external humidifier and physical seal of the fixture in commercial products increase the cost...

  8. Externalities and Compensation : Primeval Games and Solutions

    NARCIS (Netherlands)

    Ju, Y.; Borm, P.E.M.

    2005-01-01

    The classical literature (Pigou (1920), Coase (1960), Arrow (1970)) and the relatively recent studies (cf.Varian (1994)) associate the externality problem with efficiency.This paper focuses explicitly on the compensation problem in the context of externalities.To capture the features of inter-indivi

  9. Concurrent sourcing and external supplier opportunism

    DEFF Research Database (Denmark)

    Mols, Niels Peter

    When a firm simultaneously makes and buys the same components then the firm uses concurrent sourcing. This paper presents an agency model for explaining how and when concurrent sourcing reduces the likelihood of external supplier opportunism. In the proposed model, the external supplier’s expected...

  10. Crossing boundaries : Involving external parties in innovation

    NARCIS (Netherlands)

    Slot, J.H.

    2013-01-01

    To improve the return on investments in innovation, firms increasingly open up their new product development (NPD) processes by inviting external parties to participate. This dissertation focuses on the involvement of three different types of external parties in the NPD process: suppliers, customers

  11. Computing betweenness centrality in external memory

    DEFF Research Database (Denmark)

    Arge, Lars; Goodrich, Michael T.; Walderveen, Freek van

    2013-01-01

    Betweenness centrality is one of the most well-known measures of the importance of nodes in a social-network graph. In this paper we describe the first known external-memory and cache-oblivious algorithms for computing betweenness centrality. We present four different external-memory algorithms...

  12. Lattice Planar QED in external magnetic field

    CERN Document Server

    Cea, Paolo; Giudice, Pietro; Papa, Alessandro

    2011-01-01

    We investigate planar Quantum ElectroDynamics (QED) with two degenerate staggered fermions in an external magnetic field on the lattice. Our preliminary results indicate that in external magnetic fields there is dynamical generation of mass for two-dimensional massless Dirac fermions in the weak coupling region. We comment on possible implications to the quantum Hall effect in graphene.

  13. Internal and External Forces in Language Change.

    Science.gov (United States)

    Yang, Charles D.

    2000-01-01

    Develops a model of language change characterizing the dynamic interaction between internal universal grammar and external linguistic evidence, as mediated by language acquisition. Borrows insights from the study of biological evolution, where internal and external forces interact in similar fashion. Applies the model to explore the loss of the…

  14. Forms of Spanking and Children's Externalizing Behaviors

    Science.gov (United States)

    Lansford, Jennifer E.; Wager, Laura B.; Bates, John E.; Pettit, Gregory S.; Dodge, Kenneth A.

    2012-01-01

    Research suggests that corporal punishment is related to higher levels of child externalizing behavior, but there has been controversy regarding whether infrequent, mild spanking predicts child externalizing or whether more severe and frequent forms of corporal punishment account for the link. Mothers rated the frequency with which they spanked…

  15. Principles for Private and Public Internalisation of Externalities. A Synoptic View

    Directory of Open Access Journals (Sweden)

    Tatiana Mosteanu

    2009-10-01

    Full Text Available Externalities represent a market failure situation and they appear when one person´s activities influence other person´s welfare in a way that is outside the market mechanism. In contrast to the effects transmitted by market prices, externalities negatively affect the economic efficiency. They arise in everyday life and are noticed only if the effects are obvious. Ronald Coase´s approach started from the premises that externalities can be internalized. His model provides private sector means to defend against market failure. Coase´s solution to internalize externalities based on negotiation between the involved parties, given the property rights, has influenced the free market approach of market failures and today many economists consider that governments should work with the market and not against it using taxes and regulations. In the mainstream literature it is said that if for small local externalities the private sector can find solutions to solve problems, big scale externalities, such as global warming, need government intervention. As far as the last ones are concerned, we can talk about: a the Pigouvian tax, which is a tax levied on polluting activities; b the Pigouvian subsidy, given to those who suffer from negative externalities; c the subsidy paid to individuals or firms to conduct activities with positive externalities; d legal regulations, such as limits for emitting polluters and restrictions regarding the time of day or year when negative externalities can be legally produced.

  16. Quest for absolute zero in the presence of external noise.

    Science.gov (United States)

    Torrontegui, E; Kosloff, R

    2013-09-01

    A reciprocating quantum refrigerator is analyzed with the intention to study the limitations imposed by external noise. In particular we focus on the behavior of the refrigerator when it approaches the absolute zero. The cooling cycle is based on the Otto cycle with a working medium constituted by an ensemble of noninteracting harmonic oscillators. The compression and expansion segments are generated by changing an external parameter in the Hamiltonian. In this case the force constant of the harmonic oscillators mω^{2} is modified from an initial to a final value. As a result, the kinetic and potential energy of the system do not commute causing frictional losses. By proper choice of scheduling function ω(t) frictionless solutions can be obtained in the noiseless case. We examine the performance of a refrigerator subject to noise. By expanding from the adiabatic limit we find that the external noise, Gaussian phase, and amplitude noises reduce the amount of heat that can be extracted but nevertheless the zero temperature can be approached.

  17. Environmental externalities related to power production on biogas and natural gas based on the EU ExternE methodology

    DEFF Research Database (Denmark)

    Nielsen, Per Sieverts; Ibsen, Liselotte Schleisner

    1998-01-01

    This paper assesses the environmental impacts and external costs from selected electricity generation systems in Denmark. The assessment is carried out as part of the ExternE National Implementation, which is the second phase of the ExternE project and involves case studies from all Western Europ...... show that estimated damages due to the greenhouse effect are predominant, however, the uncertainty is high. The predominant damage at the local and regional level is related to emission of NOx, which results in effects on public health....... European countries. The project use a “bottom-up” methodology to evaluate the external costs associated with a wide range of different fuel cycles. The project has identified priority impacts, where most are impacts from air emissions. Externalities due to atmospheric emissions are calculated through...... the use of a software package, EcoSence, having an environmental database at both a local and regional level including population, crops, building materials and forest. The system also incorporates two air transport models, allowing local and regional scale modelling. The results of the Danish case study...

  18. [Cholesteatoma by osteoma of the external auditory canal].

    Science.gov (United States)

    Maliki, O; Aderdour, L; Ziad, T; Nouri, H; Rouchdi, Y; Marrat, A; Raji, A

    2012-01-01

    Osteoma in the external auditory canal (EAC) is an uncommon benign tumor. The association of a cholesteatoma with an osteoma of EAC is extremely rare. We report a case of a 26-year-old woman with an osteoma of the left EAC that was complicated by a cholesteatoma in the EAC between the osteoma and left tympanic membrane. Surgical removal of the osteoma and cholesteatoma proved successful by postauricular approach. The follow up without recurrence is 24 months. Osteoma of the EAC is a solitary, unilateral, and slow-growing bony benign tumor. The foremost differential diagnosis is exostose that is multiple and bilateral. Cholesteatoma of the EAC is uncommon. Its basic pathogenesis is a chronic occlusion of the EAC. Surgical treatment avoids complications related to local aggressiveness of cholesteatoma.

  19. FY08 MEMBRANE CHARACTERIZATION REPORT FOR HYBRID SULFUR ELECTROLYZER

    Energy Technology Data Exchange (ETDEWEB)

    Hobbs, D; Hector Colon-Mercado, H; Mark Elvington, M

    2008-09-01

    at SNL and Clemson. These membranes also exhibit good chemical stability and conductivity in concentrated sulfuric acid solutions and, thus, serve as promising candidates for the SDE. Therefore, we recommend further testing of these membranes including electrolyzer testing to determine if the reduced SO{sub 2} transport eliminates the formation of sulfur-containing films at the membrane/cathode interface. SO{sub 2} transport measurements in the custom built characterization cell identified experimental limitations of the original design. During the last quarter of FY08 we redesigned and fabricated a new testing cell to overcome the previous limitations. This cell also offers the capability to test membranes under polarized conditions as well as test the performance of MEAs under selected electrolyzer conditions.

  20. A porous stainless steel membrane system for extraterrestrial crop production

    Science.gov (United States)

    Koontz, H. V.; Prince, R. P.; Berry, W. L.; Knott, W. M. (Principal Investigator)

    1990-01-01

    A system was developed in which nutrient flow to plant roots is controlled by a thin (0.98 or 1.18 mm) porous (0.2 or 0.5 microns) stainless steel sheet membrane. The flow of nutrient solution through the membrane is controlled by adjusting the relative negative pressure on the nutrient solution side of the membrane. Thus, the nutrient solution is contained by the membrane and cannot escape from the compartment even under microgravity conditions if the appropriate pressure gradient across the membrane is maintained. Plant roots grow directly on the top surface of the membrane and pull the nutrient solution through this membrane interface. The volume of nutrient solution required by this system for plant growth is relatively small, since the plenum, which contains the nutrient solution in contact with the membrane, needs only to be of sufficient size to provide for uniform flow to all parts of the membrane. Solution not passing through the membrane to the root zone is recirculated through a reservoir where pH and nutrient levels are controlled. The size of the solution reservoir depends on the sophistication of the replenishment system. The roots on the surface of the membrane are covered with a polyethylene film (white on top, black on bottom) to maintain a high relative humidity and also limit light to prevent algal growth. Seeds are sown directly on the stainless steel membrane under the holes in the polyethylene film that allow a pathway for the shoots.

  1. Comparison of membrane electroporation and protein denature in response to pulsed electric field with different durations.

    Science.gov (United States)

    Huang, Feiran; Fang, Zhihui; Mast, Jason; Chen, Wei

    2013-05-01

    In this paper, we compared the minimum potential differences in the electroporation of membrane lipid bilayers and the denaturation of membrane proteins in response to an intensive pulsed electric field with various pulse durations. Single skeletal muscle fibers were exposed to a pulsed external electric field. The field-induced changes in the membrane integrity (leakage current) and the Na channel currents were monitored to identify the minimum electric field needed to damage the membrane lipid bilayer and the membrane proteins, respectively. We found that in response to a relatively long pulsed electric shock (longer than the membrane intrinsic time constant), a lower membrane potential was needed to electroporate the cell membrane than for denaturing the membrane proteins, while for a short pulse a higher membrane potential was needed. In other words, phospholipid bilayers are more sensitive to the electric field than the membrane proteins for a long pulsed shock, while for a short pulse the proteins become more vulnerable. We can predict that for a short or ultrashort pulsed electric shock, the minimum membrane potential required to start to denature the protein functions in the cell plasma membrane is lower than that which starts to reduce the membrane integrity.

  2. Spatiotemporal Organization of Spin-Coated Supported Model Membranes

    Science.gov (United States)

    Simonsen, Adam Cohen

    biomembranes is randomly organized to facilitate membrane function. However, during the last 10-20 years it has become increasingly clear that the components of biomembranes are not randomly organized but that the lateral distribution is heterogeneous and time dependent. A picture is emerging where the interactions among membrane components and between membranes and external structures give rise to dynamically maintained domains with distinct sizes and compositions. Such domains are coupled to membrane function through their regulation of membrane-bound proteins. Experimentally, the investigation of domain structures in artificial and natural membranes have been enhanced by the proposition of the so-called raft hypothesis [5-7]. According to this hypothesis, rafts are nanoscale regions of biological membranes that are linked to important cellular processes and signaling pathways [8,9]. Rafts originated as insoluble membrane fragments upon treatment of cellular membranes with cold detergent [10].

  3. Proteins causing membrane fouling in membrane bioreactors.

    Science.gov (United States)

    Miyoshi, Taro; Nagai, Yuhei; Aizawa, Tomoyasu; Kimura, Katsuki; Watanabe, Yoshimasa

    2015-01-01

    In this study, the details of proteins causing membrane fouling in membrane bioreactors (MBRs) treating real municipal wastewater were investigated. Two separate pilot-scale MBRs were continuously operated under significantly different operating conditions; one MBR was a submerged type whereas the other was a side-stream type. The submerged and side-stream MBRs were operated for 20 and 10 days, respectively. At the end of continuous operation, the foulants were extracted from the fouled membranes. The proteins contained in the extracted foulants were enriched by using the combination of crude concentration with an ultrafiltration membrane and trichloroacetic acid precipitation, and then separated by two-dimensional polyacrylamide gel electrophoresis (2D-PAGE). The N-terminal amino acid sequencing analysis of the proteins which formed intensive spots on the 2D-PAGE gels allowed us to partially identify one protein (OmpA family protein originated from genus Brevundimonas or Riemerella anatipestifer) from the foulant obtained from the submerged MBR, and two proteins (OprD and OprF originated from genus Pseudomonas) from that obtained from the side-stream MBR. Despite the significant difference in operating conditions of the two MBRs, all proteins identified in this study belong to β-barrel protein. These findings strongly suggest the importance of β-barrel proteins in developing membrane fouling in MBRs.

  4. Surface modification of titanium membrane by chemical vapor deposition and its electrochemical self-cleaning

    Science.gov (United States)

    Li, X. W.; Li, J. X.; Gao, C. Y.; Chang, M.

    2011-10-01

    Membrane separation is applied widely in many fields, while concentration polarization and membrane fouling, limiting its promotion and application greatly, are the bottlenecks in membrane application. Among which, membrane fouling is irreversible, membrane must be periodically cleaned or even replaced to restore permeability. Membrane cleaning has become one of the key issues in membrane separation areas. Considering incomparable electrochemical advantages of boron-doped diamond (BDD) film electrode over conventional electrode, a new composite membrane Ti/BDD, made by depositing CVD (chemical vapor deposition) boron-doped diamond film on titanium(Ti) membrane to modify porous titanium surface, that can be cleaned electrochemically is proposed. Feasibility of its preparation and application is discussed in this paper. Results shows that based on the unique electrochemical properties of diamond, cleaning level of this composite Ti/BDD membrane is significantly increased, making membrane life and efficiency improved prominently.

  5. Polyarylether composition and membrane

    Science.gov (United States)

    Hung, Joyce; Brunelle, Daniel Joseph; Harmon, Marianne Elisabeth; Moore, David Roger; Stone, Joshua James; Zhou, Hongyi; Suriano, Joseph Anthony

    2010-11-09

    A composition including a polyarylether copolymer is provided. The copolymer includes a polyarylether backbone; and a sulfonated oligomeric group bonded to the polyarylether suitable for use as a cation conducting membrane. Method of bonding a sulfonated oligomeric group to the polyarylether backbone to form a polyarylether copolymer. The membrane may be formed from the polyarylether copolymer composition. The chain length of the sulfonated oligomeric group may be controlled to affect or control the ion conductivity of the membrane.

  6. Membrane binding domains

    OpenAIRE

    Hurley, James H.

    2006-01-01

    Eukaryotic signaling and trafficking proteins are rich in modular domains that bind cell membranes. These binding events are tightly regulated in space and time. The structural, biochemical, and biophysical mechanisms for targeting have been worked out for many families of membrane binding domains. This review takes a comparative view of seven major classes of membrane binding domains, the C1, C2, PH, FYVE, PX, ENTH, and BAR domains. These domains use a combination of specific headgroup inter...

  7. Applications of membrane computing

    CERN Document Server

    Ciobanu, Gabriel; Păun, Gheorghe

    2006-01-01

    Membrane computing is a branch of natural computing which investigates computing models abstracted from the structure and functioning of living cells and from their interactions in tissues or higher-order biological structures. The models considered, called membrane systems (P systems), are parallel, distributed computing models, processing multisets of symbols in cell-like compartmental architectures. In many applications membrane systems have considerable advantages - among these are their inherently discrete nature, parallelism, transparency, scalability and nondeterminism. In dedicated cha

  8. Economics of vanadium redox flow battery membranes

    Science.gov (United States)

    Minke, Christine; Turek, Thomas

    2015-07-01

    The membrane is a key component of the vanadium redox flow battery (VRFB) in terms of electrochemical performance as well as costs. The standard material Nafion® is cost intensive and therefore several alternative materials are in the focus of research. In this paper a substantial analytical approach is presented in order to quantify bottom price limits for different types of membranes. An in-depth analysis of material and production cost allows statements concerning cost potentials of different ion exchange membranes (IEM) and nano filtration membranes (NFM). The final result reveals that expected costs of IEM and NFM at high production volumes differ by one order of magnitude. Moreover, an analysis of the current market situation is made to provide a framework for economic considerations at present.

  9. Use of Automated External Defibrillators

    Energy Technology Data Exchange (ETDEWEB)

    Gregory K Christensen

    2009-02-01

    In an effort to improve survival from cardiac arrest, the American Heart Association (AHA) has promoted the Chain of Survival concept, describing a sequence of prehospital steps that result in improved survival after sudden cardiac arrest. These interventions include immediate deployment of emergency medical services, prompt cardiopulmonary resuscitation, early defibrillation when indicated, and early initiation of advanced medical care. Early defibrillation has emerged as the most important intervention with survival decreasing by 10% with each minute of delay in defibrillation. Ventricular Fibrillation (VF) is a condition in which there is uncoordinated contraction of the heart cardiac muscle of the ventricles in the heart, making them tremble rather than contract properly. VF is a medical emergency and if the arrhythmia continues for more than a few seconds, blood circulation will cease, and death can occur in a matter of minutes. During VF, contractions of the heart are not synchronized, blood flow ceases, organs begin to fail from oxygen deprivation and within 10 minutes, death will occur. When VF occurs, the victim must be defibrillated in order to establish the heart’s normal rhythm. On average, the wait for an ambulance in populated areas of the United States is about 11 minutes. In view of these facts, the EFCOG Electrical Safety Task Group initiated this review to evaluate the potential value of deployment and use of automated external defibrillators (AEDs) for treatment of SCA victims. This evaluation indicates the long term survival benefit to victims of SCA is high if treated with CPR plus defibrillation within the first 3-5 minutes after collapse. According to the American Heart Association (AHA), survival rates as high as 74% are possible if treatment and defibrillation is performed in the first 3 minutes. In contrast survival rates are only 5% where no AED programs have been established to provide prompt CPR and defibrillation. ["CPR statistics

  10. Gas separation membranes

    Science.gov (United States)

    Schell, William J.

    1979-01-01

    A dry, fabric supported, polymeric gas separation membrane, such as cellulose acetate, is prepared by casting a solution of the polymer onto a shrinkable fabric preferably formed of synthetic polymers such as polyester or polyamide filaments before washing, stretching or calendering (so called griege goods). The supported membrane is then subjected to gelling, annealing, and drying by solvent exchange. During the processing steps, both the fabric support and the membrane shrink a preselected, controlled amount which prevents curling, wrinkling or cracking of the membrane in flat form or when spirally wound into a gas separation element.

  11. Anion exchange membrane

    Science.gov (United States)

    Verkade, John G; Wadhwa, Kuldeep; Kong, Xueqian; Schmidt-Rohr, Klaus

    2013-05-07

    An anion exchange membrane and fuel cell incorporating the anion exchange membrane are detailed in which proazaphosphatrane and azaphosphatrane cations are covalently bonded to a sulfonated fluoropolymer support along with anionic counterions. A positive charge is dispersed in the aforementioned cations which are buried in the support to reduce the cation-anion interactions and increase the mobility of hydroxide ions, for example, across the membrane. The anion exchange membrane has the ability to operate at high temperatures and in highly alkaline environments with high conductivity and low resistance.

  12. Photoresponsive nanostructured membranes

    KAUST Repository

    Madhavan, P.

    2016-07-26

    The perspective of adding stimuli-response to isoporous membranes stimulates the development of separation devices with pores, which would open or close under control of environment chemical composition, temperature or exposure to light. Changes in pH and temperature have been previously investigated. In this work, we demonstrate for the first time the preparation of photoresponsive isoporous membranes, applying self-assembly non-solvent induced phase separation to a new light responsive block copolymer. First, we optimized the membrane formation by using poly(styrene-b-anthracene methyl methacrylate-b-methylmethacrylate) (PS-b-PAnMMA-b-PMMA) copolymer, identifying the most suitable solvent, copolymer block length, and other parameters. The obtained final triblock copolymer membrane morphologies were characterized using atomic force and electron microscopy. The microscopic analysis reveals that the PS-b-PAnMMA-b-PMMA copolymer can form both lamellar and ordered hexagonal nanoporous structures on the membrane top layer in appropriate solvent compositions. The nanostructured membrane emits fluorescence due to the presence of the anthracene mid-block. On irradiation of light the PS-b-PAnMMA-b-PMMA copolymer membranes has an additional stimuli response. The anthracene group undergoes conformational changes by forming [4 + 4] cycloadducts and this alters the membrane\\'s water flux and solute retention. © 2016 The Royal Society of Chemistry.

  13. Emission efficiency limit of Si nanocrystals

    NARCIS (Netherlands)

    Limpens, R.; Luxembourg, S.L.; Weeber, A.W.; Gregorkiewicz, T.

    2016-01-01

    One of the important obstacles on the way to application of Si nanocrystals for development of practical devices is their typically low emissivity. In this study we explore the limits of external quantum yield of photoluminescence of solid-state dispersions of Si nanocrystals in SiO2. By making use

  14. Enhancing inhibited fermentations through a dynamic electro-membrane bioreactor

    DEFF Research Database (Denmark)

    Prado Rubio, Oscar Andres; Garde, Arvid; Rype, Jens-Ulrik

    its strong potential for increasing productivity and product yield has been verified. REED uses ion exchange membranes and electrical potential gradients to selectively separate the target ion. The main limitation of using membrane separation combined with bioreactors is membrane fouling. REED...... technology ensures long operation time by reversing periodically the polarity of the imposed electrical field to significantly reduce the influence of membrane fouling. The periodic nature of the electrically driven membrane separation process makes the membrane bioreactor operation non trivial....... This challenging operation is associated with different dynamic behaviors of the individual units plus their interaction. The purpose of this contribution is to show the results of experimental and model based efforts done in order to investigate the operation of a membrane bioreactor. From modeling point of view...

  15. Hydrogen separation membranes annual report for FY 2006.

    Energy Technology Data Exchange (ETDEWEB)

    Balachandran, U.; Chen, L.; Ciocco, M.; Doctor, R. D.; Dorris, S.E.; Emerson, J. E.; Fisher, B.; Lee, T. H.; Killmeyer, R. P.; Morreale,B.; Picciolo, J. J.; Siriwardane, R. V.; Song, S. J.

    2007-02-05

    The objective of this work is to develop dense ceramic membranes for separating hydrogen from other gaseous components in a nongalvanic mode, i.e., without using an external power supply or electrical circuitry. This goal of this project is to develop two types of dense ceramic membrane for producing hydrogen nongalvanically, i.e., without electrodes or external power supply, at commercially significant fluxes under industrially relevant operating conditions. The first type of membrane, hydrogen transport membranes (HTMs), will be used to separate hydrogen from gas mixtures such as the product streams from coal gasification, methane partial oxidation, and water-gas shift reactions. Potential ancillary uses of HTMs include dehydrogenation and olefin production, as well as hydrogen recovery in petroleum refineries and ammonia synthesis plants, the largest current users of deliberately produced hydrogen. The second type of membrane, oxygen transport membranes (OTMs), will produce hydrogen by nongalvanically removing oxygen that is generated when water dissociates at elevated temperatures. This report describes progress that was made during FY 2006 on the development of OTM and HTM materials.

  16. Improvement of the Calculation of Scattering Amplitudes with External Fermions

    CERN Document Server

    Chopin, E

    1998-01-01

    In this paper, we expose an improvement of a method for computing scattering amplitudes that include external fermions (with polarization) with the following features: the formulas are quite general and work for different kinematic configurations and different external masses, they are explicitely covariant, they do not depend on a specific representation of the Dirac matrices and they have a meaningful limit when the masses tend to 0. The results presented make use of some well known formulas describing the density matrices in terms of projection operators within a more general formalism. Since our formulas intend to be as general as possible, we also take into account the possibility of a transverse polarization for massless fermions.

  17. Thermal design of the Space Shuttle External Tank

    Science.gov (United States)

    Warmbrod, J. D.; Vaniman, J. L.; Elam, B. F.

    1981-01-01

    The history of the engineering and manufacturing requirements leading to the final Thermal Protection System (TPS) for the External Tank (ET) is presented. The thermal design for the ET must be optimized, based on considerations of cost, weight, and application of the TPS. The significant thermal requirements include the structural and component temperature limits, the propellant quality, the minimization of ice and frost, no air liquefaction, and no film boiling. The TPS materials selected to meet the requirements are a low density closed cell foam (CPR-488) and two light-weight ablators (SLA-56 and MA-25s). The first four flights of the Space Shuttle (1981) will measure and evaluate external environmental, structural, propulsion, electrical, and engine performance data. The ET will be instrumented to measure acoustics, pressures, heat transfer, vibration, temperatures, and structural strains. TPS weight reductions are planned for future ETs through the use of a comprehensive thermal instrumentation system.

  18. Internal and External Collaboration in New Product Development

    DEFF Research Database (Denmark)

    Timenes Laugen, Bjørge; Lassen, Astrid Heidemann; Middel, Rick;

    2009-01-01

    in firms in B2C markets aiming at increasing the innovation volume. For B2B companies the reverse picture emerges. However, when the aim is to increase the radicality of new products, suppliers and customers are heavily involved for firms in B2B markets. Further, market uncertainty, and to some extent...... the competitiveness of companies. Although the idea of involving internal and external actors in the new product development (NPD) process is not new, the knowledge about the benefits and pitfalls is still limited. This paper aims to contribute to refining the concept of open innovation, by investigating how...... strategic priorities influence the degree of external and internal involvement in the NPD process, moderated by contextual factors. Results based on analyses of 584 companies from the International Manufacturing Strategy Survey (IMSS) 2005 indicate that suppliers are heavily involved in the NPD process...

  19. How a membrane agent buys goods in a membrane store

    Institute of Scientific and Technical Information of China (English)

    Rudolf Freund; Marion Oswald; Thomas Schirk

    2007-01-01

    In this paper we consider a specific model of membrane systems, i.e. membrane systems with attributes. In these systems, the information is placed at the membranes in form of attributes, no objects are considered inside the membranes except for other membranes. The membrane system with attributes evolves according to rules that compute new values for the attributes from the attributes assigned to the membranes involved in the rule. The model of membrane systems with attributes allows us to specify business transactions in a precise way and to simulate different models for such transactions with a suitable tool for membrane systems with attributes.

  20. Molecular Modeling of Interfacial Proton Transport in Polymer Electrolyte Membranes

    OpenAIRE

    2014-01-01

    The proton conductivity of polymer electrolyte membranes (PEMs) plays a crucial role for the performance of polymer electrolyte fuel cells (PEFCs). High hydration of Nafion-like membranes is crucial to high proton conduction across the PEM, which limits the operation temperature of PEFCs to <100o C. At elevated temperatures (>100o C) and minimal hydration, interfacial proton transport becomes vital for membrane operation. Along with fuel cell systems, interfacial proton conduction is of...

  1. Preparation and Optimization of a Membrane for 3rd Generation Solvent Membrane Contactor

    OpenAIRE

    Arif, Asad

    2016-01-01

    Third generation solvent is a new class of CO2 absorbents with a great potential in terms of reduction of the regeneration energy requirement for post combustion carbon capture, but their use at the industrial scale is limited by their high volatility. Membrane contactor technology is proposed as possible solution, but the membrane layer must be purposely designed in order to act as amine barrier, without negatively affecting the overall CO2 mass transfer resistance. Teflon AF2400 has been re...

  2. Association of Dermatological Conditions of External Ear with the Use of Cotton Buds

    Directory of Open Access Journals (Sweden)

    Salahuddin Ahmed

    2014-09-01

    Full Text Available Background: The habit of cleaning the external auditory canal with cotton buds is a common practice of the masses. It has strong association with neurodermatitis and contact dermatitis of the external ear. It is also associated with acute otitis externa, rupture of tympanic membrane causing bleeding and temporary hearing loss in some cases. In many cases the injury will heal but damage to minuscule bones deep inside the ear can cause permanent deafness. Objective: The objective of this study was to determine the association of dermatological condition of external ear with the use of cotton buds. Materials and Methods: This case control study was done from January to October 2012 in the Ear Nose Throat Department of Pakistan Level III Hospital, Darfur, Sudan. Sixty seven patients with dermatological diseases of external ear were cases and 83 subjects without dermatological diseases of external ear were selected as controls. Results: Among 67 cases, 58 were cotton bud users and among 83 controls only 29 were cotton bud users. Different types of dermatological diseases were neurodermatitis (34.32%, otitis externa (28.36%, contact dermatitis (26.87% and wax impaction (8.95%. Ninety three percent of cotton bud users were ignorant of harmful effects of this bad habit. Conclusion: There is a strong association of dermatological diseases of external ear with the use of cotton bud which should be discouraged by fortifying the warning by manufacturers and health education at various educational levels.

  3. External quality assurance in Malaysia.

    Science.gov (United States)

    Nawawi, H; Lim, H H; Zakiah, I

    1999-01-01

    An activity supportive of the MOH QA Programme, the National EQAS for clinical chemistry monitors for analytical performance in core routine biochemical testing by the pathology laboratories, with unsatisfactory performance scores serving to alert against deficiencies or problems and the scores in subsequent challenges providing the feedback of effectiveness of remedial actions taken. While unacceptable individual analyte performance score (variance index score, VIS) indicated problems in instruments, reagent and calibrators, or the use of inherently poorer methods, repeated occurrence of unsatisfactory OMRVIS was traceable to generally poor laboratory management of usually inadequately-equipment small laboratories. The outcome has been one of slow but gradual improvement in the overall performance of participating laboratories, with a move towards methods upgrading and standardization to achieve greater concordance of results. Presently, the programme is limited to 61 government and 4 private hospital laboratories in the country for 12 commonly assayed clinical biochemistry analytes. It is hoped that the NEQAS could be extended to the other private laboratories and that of academic institutions. However, this is dependent to a large extent on the manpower and financial support obtainable by the organizing body of the programme in the future. Belk and Sunderman, 1947 demonstrated that laboratories participating in an quality assessment scheme could rapidly and dramatically improve their analytical performance. In some countries, participation has become mandatory, and acceptable performance is a requirement in laboratory accreditation. The need and value of the NEQAP is, therefore, evident. While there may be limitations in the national programme. efforts are being made at improving the programme within the means and resources of the organising body. The goals of the NEQAP are not just to monitor performance but also to educate. On this, matters related to and

  4. Concurrent sourcing and external supplier opportunism

    DEFF Research Database (Denmark)

    Mols, Niels Peter

    When a firm simultaneously makes and buys the same components then the firm uses concurrent sourcing. This paper presents an agency model for explaining how and when concurrent sourcing reduces the likelihood of external supplier opportunism. In the proposed model, the external supplier’s expected...... costs of opportunism are determined as a product of four factors. The four factors are: likelihood of discovering supplier opportunism, buyer’s internalized quantity as reaction to supplier opportunism, asset specificity of external supplier’s investments, and multiplicator effects. Each...

  5. Environment and externalization; Environnement et externalisation

    Energy Technology Data Exchange (ETDEWEB)

    Kremlis, G.; Renaud, R. [Association francaise des ingenieurs et techniciens de l' environnement, AFITE, 75 - Paris (France); Touron, M. [Veritas, 75 - Paris (France)] [and others

    2001-07-01

    This document presents the discussions of the 16 may 2000, concerning the externalization and the environment and proposes to answer the following questions: is the externalization a new strategy to better perceive, hopeful engineering department, the technological risks problems, the environment or the land pollution? Does the externalization allow a better organization of the enterprise? To analyse the situation, the document presents the white book of the environmental liability, the administration point of view, some enterprises examples and the importance of the environmental management. (A.L.B.)

  6. Leiomyosarcoma of the external iliac vein.

    Science.gov (United States)

    Fukuda, Wakako; Taniguchi, Satoshi; Fukuda, Ikuo

    2012-06-01

    Leiomyosarcoma of the iliac vein is an uncommon tumor. We report a case of a 63-year-old Japanese woman with leiomyosarcoma of the right external iliac vein. The patient complained of right inguinal pain and swelling. Computed tomography demonstrated a mass surrounding the right external iliac artery and vein. Metastases in the lungs and liver were found. Complete resection of the tumor along with the involved vessels was performed. Polytetrafluoroethylene grafts were used to reconstruct the vessels. Pathological examination revealed leiomyosarcoma of the external iliac vein. Although the prognosis of leiomyosarcoma is poor, en bloc tumor resection is the treatment of choice.

  7. The sustainability of Serbia's external position: The impact of fiscal adjustment and external shocks

    Directory of Open Access Journals (Sweden)

    Zildžović Emir

    2015-01-01

    Full Text Available This paper studies the impact of fiscal policy and external shocks on the sustainability of Serbia’s external position. The key determinants of Serbia's current account balance are identified using model averaging techniques and are compared with estimates obtained for other small open economies (Poland, Georgia, Morocco, Ukraine, and Estonia. The paper uses estimated influences of macrovariables on the current account balance to generate a rich set of possible outcomes for the external position of the country. The results suggest the importance of fiscal policy for the reduction of external imbalances in all countries in our sample. In particular, credible and sustained fiscal adjustment can reduce current account deficit and stabilize Serbia’s external position close to its current level over the medium term. The analysis also warns that lack of success in fiscal consolidation coupled with external shocks may easily push the external position onto an unsustainable path.

  8. Temporization of penetrating abdominal-pelvic trauma with manual external aortic compression: a novel case report.

    Science.gov (United States)

    Douma, Matthew; Smith, Katherine E; Brindley, Peter G

    2014-07-01

    A young civilian man experienced multiple gunshots to the lower abdomen, pelvis, and thigh. These were not amenable to direct compression by a single rescuer. This report outlines the first case in the peer-reviewed literature of manual external aortic compression after severe trauma. This technique successfully temporized external bleeding for more than 10 minutes and restored consciousness to the moribund victim. Subsequently, external bleeding could not be temporized by a second smaller rescuer, or during ambulance transfer. Therefore, we also gained insights about the possible limits of bimanual compression and when alternates, such as pneumatic devices, may be required. Research is needed to test our presumption that successful bimanual compression requires larger-weight rescuers, smaller-weight victims, and a hard surface. It is therefore unclear whether manual external aortic compression is achievable by most rescuers or for most victims. However, it offers an immediate and equipment-free life-sustaining strategy when there are limited alternatives.

  9. Structural basis for lipopolysaccharide insertion in the bacterial outer membrane.

    Science.gov (United States)

    Qiao, Shuai; Luo, Qingshan; Zhao, Yan; Zhang, Xuejun Cai; Huang, Yihua

    2014-07-03

    One of the fundamental properties of biological membranes is the asymmetric distribution of membrane lipids. In Gram-negative bacteria, the outer leaflet of the outer membrane is composed predominantly of lipopolysaccharides (LPS). The export of LPS requires seven essential lipopolysaccharide transport (Lpt) proteins to move LPS from the inner membrane, through the periplasm to the surface. Of the seven Lpt proteins, the LptD-LptE complex is responsible for inserting LPS into the external leaflet of the outer membrane. Here we report the crystal structure of the ∼110-kilodalton membrane protein complex LptD-LptE from Shigella flexneri at 2.4 Å resolution. The structure reveals an unprecedented two-protein plug-and-barrel architecture with LptE embedded into a 26-stranded β-barrel formed by LptD. Importantly, the secondary structures of the first two β-strands are distorted by two proline residues, weakening their interactions with neighbouring β-strands and creating a potential portal on the barrel wall that could allow lateral diffusion of LPS into the outer membrane. The crystal structure of the LptD-LptE complex opens the door to new antibiotic strategies targeting the bacterial outer membrane.

  10. External conference: UNIVERSITE DE GENEVE

    CERN Multimedia

    2007-01-01

    Ecole de physique Département de physique nucléaire et corspusculaire 24, Quai Ernest-Ansermet
1211 GENEVE 4
Tél: (022) 379 62 73
Fax: (022) 379 69 92 Wednesday 26th September 2007 PARTICLE PHYSICS SEMINAR at 17.00 hrs - Stückelberg Auditorium Precision determinations of |Vcb| and |Vub| by Dr U. Phillip / University of Melbourne The success of the B factories has dramatically improved our understanding of CP violation. The search for clear signs of new physics through measurements of CP violation is limited by understanding of the CKM elements |Vub| and |Vcb|. Improvement of our knowledge of the least well known CKM parameter, |Vub|, therefore directly translates to a more stringent test of the Standard Model. The prodigious samples of B meson decays available at the B factories, along with advances in the theory involving semileptonic B decays, have been used to provide a determination of both, |Vcb| and the b-quark mass, with a precision of 1%, and bring the pr...

  11. Single-molecule force spectroscopy of membrane proteins from membranes freely spanning across nanoscopic pores.

    Science.gov (United States)

    Petrosyan, Rafayel; Bippes, Christian A; Walheim, Stefan; Harder, Daniel; Fotiadis, Dimitrios; Schimmel, Thomas; Alsteens, David; Müller, Daniel J

    2015-05-13

    Single-molecule force spectroscopy (SMFS) provides detailed insight into the mechanical (un)folding pathways and structural stability of membrane proteins. So far, SMFS could only be applied to membrane proteins embedded in native or synthetic membranes adsorbed to solid supports. This adsorption causes experimental limitations and raises the question to what extent the support influences the results obtained by SMFS. Therefore, we introduce here SMFS from native purple membrane freely spanning across nanopores. We show that correct analysis of the SMFS data requires extending the worm-like chain model, which describes the mechanical stretching of a polypeptide, by the cubic extension model, which describes the bending of a purple membrane exposed to mechanical stress. This new experimental and theoretical approach allows to characterize the stepwise (un)folding of the membrane protein bacteriorhodopsin and to assign the stability of single and grouped secondary structures. The (un)folding and stability of bacteriorhodopsin shows no significant difference between freely spanning and directly supported purple membranes. Importantly, the novel experimental SMFS setup opens an avenue to characterize any protein from freely spanning cellular or synthetic membranes.

  12. Regulation of hydrogen production by Enterobacter aerogenes by external NADH and NAD{sup +}

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Chong; Ma, Kun; Xing, Xin-Hui [Department of Chemical Engineering, Tsinghua University, Beijing 100084 (China)

    2009-02-15

    Experiments involving the addition of external nicotinamide adenine dinucleotide, reduced form (NADH) or nicotinamide adenine dinucleotide (NAD{sup +}) have been designed to examine how the hydrogen in Enterobacter aerogenes is liberated by NADH or NAD{sup +}. The addition of external NADH or NAD{sup +} was found to regulate hydrogen production by E. aerogenes in resting cells, batch cultures, and chemostat cultures. Particularly in chemostat cultivation, with the external addition of NADH, hydrogen production via the NADH pathway was decreased, while that via the formate pathway was increased; in the end, the overall hydrogen p was decreased. The addition of NAD{sup +}, on the other hand, gave the opposite results. The membrane-bound hydrogenase was found to play a central role in regulating hydrogen production. The occurrence of NADH oxidation (NAD{sup +} reduction) on the cell membrane resulted in an electron flow across the membrane; this changed the oxidation state and metabolic pattern of the cells, which eventually affected the hydrogen evolution. (author)

  13. Yeast Kch1 and Kch2 membrane proteins play a pleiotropic role in membrane potential establishment and monovalent cation homeostasis regulation.

    Science.gov (United States)

    Felcmanova, Kristina; Neveceralova, Petra; Sychrova, Hana; Zimmermannova, Olga

    2017-08-01

    The Kch1 and Kch2 plasma-membrane proteins were identified in Saccharomyces cerevisiae as being essential for the activation of a high-affinity Ca2+ influx system. We searched for Kch proteins roles in the maintenance of cation homeostasis and tested the effect of kch1 and/or kch2 deletions on various physiological parameters. Compared to wild-type, kch1 kch2 mutant cells were smaller, relatively hyperpolarised, grew better under limited K+ conditions and exhibited altered growth in the presence of monovalent cations. The absence of Kch1 and Kch2 did not change the intracellular pH in cells growing at low potassium or the tolerance of cells to divalent cations, high concentration of sorbitol or extreme external pH. The overexpression of KCH1 only increased the intracellular pH in the presence of elevated K+ in media. None of the phenotypes associated with the deletion of KCH1 and KCH2 in wild type were observed in a strain lacking KCH genes and main K+ uptake systems Trk1 and Trk2. The role of the Kch homologue in cation homeostasis was also tested in Candida albicans cells. Our data demonstrate that Kch proteins significantly contribute to the maintenance of optimal cation homeostasis and membrane potential in S. cerevisiae but not in C. albicans. © FEMS 2017. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

  14. Plasma membrane ATPases

    DEFF Research Database (Denmark)

    Palmgren, Michael Broberg; Bækgaard, Lone; Lopez Marques, Rosa Laura

    2011-01-01

    The plasma membrane separates the cellular contents from the surrounding environment. Nutrients must enter through the plasma membrane in order to reach the cell interior, and toxic metabolites and several ions leave the cell by traveling across the same barrier. Biological pumps in the plasma me...

  15. Thin supported silica membranes

    NARCIS (Netherlands)

    Zivkovic, Tijana

    2007-01-01

    This thesis discusses several transport-related aspects relevant for the application of thin supported silica membranes for gas separation and nanofiltration. The influence of support geometry on overall membrane performance is investigated. Planar (i.e., flat plate), tubular, and multichannel suppo

  16. Membrane capacitive deionization

    NARCIS (Netherlands)

    Biesheuvel, P.M.; Wal, van der A.

    2010-01-01

    Membrane capacitive deionization (MCDI) is an ion-removal process based on applying an electrical potential difference across an aqueous solution which flows in between oppositely placed porous electrodes, in front of which ion-exchange membranes are positioned. Due to the applied potential, ions ar

  17. Concerted diffusion of lipids in raft-like membranes

    NARCIS (Netherlands)

    Apajalahti, Touko; Niemela, Perttu; Govindan, Praveen Nedumpully; Miettinen, Markus S.; Salonen, Emppu; Marrink, Siewert-Jan; Vattulainen, Ilpo

    2010-01-01

    Currently, there is no comprehensive model for the dynamics of cellular membranes. The understanding of even the basic dynamic processes, such as lateral diffusion of lipids, is still quite limited. Recent studies of one-component membrane systems have shown that instead of single-particle motions,

  18. Use of biomimetic forward osmosis membrane for trace organics removal

    DEFF Research Database (Denmark)

    Madsen, Henrik T.; Bajraktari, Niada; Helix Nielsen, Claus

    2015-01-01

    organic pollutants, which limits the applicability of the forward osmosis process. In this study a newly developed biomimetic membrane was tested for the removal of three selected trace organics that can be considered as a bench marking test for a membrane[U+05F3]s ability to reject small neutral organic...

  19. Emissivity of freestanding membranes with thin metal coatings

    NARCIS (Netherlands)

    Zwol, van P.J.; Vles, D.F.; Voorthuijzen, W.P.; Péter, M.; Vermeulen, H.; Zande, W.J.; Sturm, J.M.; Kruijs, van de R.W.E.; Bijkerk, F.

    2015-01-01

    Freestanding silicon nitride membranes with thicknesses down to a few tens of nanometers find use as TEM windows or soft X-ray spectral purity filters. As the thickness of a membrane decreases, emissivity vanishes, which limits radiative heat emission and resistance to heat loads. We show that thin

  20. Polyene antibiotic that inhibits membrane transport proteins

    NARCIS (Netherlands)

    Te Welscher, Y.M.; van Leeuwen, M.R.; de Kruijff, B.; Dijksterhuis, J.; Breukink, E.

    2012-01-01

    The limited therapeutic arsenal and the increase in reports of fungal resistance to multiple antifungal agents have made fungal infections a major therapeutic challenge. The polyene antibiotics are the only group of antifungal antibiotics that directly target the plasma membrane via a specific inter