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Sample records for basilar membrane

  1. Mechanics of the basilar membrane in Caiman crocodilus.

    Science.gov (United States)

    Wilson, J P; Smolders, J W; Klinke, R

    1985-04-01

    Vibration measurements were made at a number of positions near the proximal (basal) end of the basilar membrane, and on the columella footplate, of Caiman crocodilus using a capacitive probe. The measurements established the existence of a mechanical travelling wave in this species. They showed no significant change of mechanical tuning with temperature, and were highly significantly different from previous reports of neural temperature sensitivity (Smolders, J. and Klinke, R. (1984): J. Comp. Physiol. 155, 19-30). Thus the neural sensitivity to temperature change appears not to depend upon basilar membrane mechanics. One interpretation of this is that the basilar membrane passively precedes an active temperature-sensitive filter. It was also found that the limbus supporting the basilar membrane had a measurable, but unturned, vibration and that the effect of draining scala tympani for the measurements was to increase the basilar membrane tuning frequency by a factor of about 1.5.

  2. Are active elements necessary in the basilar membrane impedance?

    Science.gov (United States)

    Diependaal, R J; Viergever, M A; de Boer, E

    1986-07-01

    This article is motivated by the current hypothesis [Kim et al., Psychological, Physiological and Behavioural Studies in Hearing (Delft U. P., The Netherlands, 1980); Neely, Doctoral dissertation, Washington University, St. Louis, MO (1981); de Boer, J. Acoust. Soc. Am. 73, 567-573 (1983a) and 73, 574-576 (1983b)] that it is necessary to include active elements in the basilar membrane (BM) impedance in order to explain recent data on the vibration of the BM [Khanna and Leonard, Science 215, 305-306 (1982); Sellick et al., J. Acoust. Soc. Am. 72, 131-141 (1982); Robles et al., Peripheral Auditory Mechanisms (Springer, New York, 1986)]. In order to test this hypothesis, first, a method which is an inversion of the customary description of cochlear mechanics is described. Instead of computing the BM velocity for a given point impedance of the membrane, we show how to compute the impedance function from a given BM velocity pattern in response to a sinusoidal input at the stapes. This method is then used to study the sensitivity of the recovered impedance to perturbations in the velocity pattern. The simulations used show that the real part of the impedance is extremely sensitive to such perturbations. Therefore, measured velocity patterns are unlikely to resolve the issue of whether active elements should be included. Frequency responses measured at a few points on the membrane are even less likely to do so.

  3. A Brownian Energy Depot Model of the Basilar Membrane Oscillation with a Braking Mechanism

    CERN Document Server

    Zhang, Yong; Lee, Kong-Ju-Bock; Park, Youngah

    2008-01-01

    High auditory sensitivity, sharp frequency selectivity, and otoacoustic emissions are signatures of active amplification of the cochlea. The human ear can also detect very large amplitude sound without being damaged as long as the exposed time is not too long. The outer hair cells are believed as the best candidate for the active force generator of the mammalian cochlea. In this paper, we propose a new model for the basilar membrane oscillation which successfully describes both the active and the protective mechanisms by employing an energy depot concept and a critical velocity of the basilar membrane. One of the main results is that thermal noise in the absence of external stimulation can be amplified leading to the spontaneous basilar membrane oscillation. The compressive response of the basilar membrane at the characteristic frequency and the dynamic response to the stimulation are consistent with the experimental results as expected. Our model also shows the nonlinear distortion of the response of the bas...

  4. Analysis of an impulse response measured at the basilar membrane of the chinchilla (L)

    NARCIS (Netherlands)

    Wit, Hero P.; Bell, Andrew

    2015-01-01

    In a recent paper [J. Acoust. Soc. Am. 133, 2224-2239 (2013)], Shera and Cooper report on the impulse response of the basilar membrane (BM) of a chinchilla, a waveform which shows repetitive bursts. They explain the bursts in terms of repeated coherent reflection at BM discontinuities and partial re

  5. Electrically evoked reticular lamina and basilar membrane vibrations in mice with alpha tectorin C1509G mutation

    Science.gov (United States)

    Ren, Tianying; He, Wenxuan

    2015-12-01

    Mechanical coupling between the tectorial membrane and the hair bundles of outer hair cells is crucial for stimulating mechanoelectrical transduction channels, which convert sound-induced vibrations into electrical signal, and for transmitting outer hair cell-generated force back to the basilar membrane to boost hearing sensitivity. It has been demonstrated that the detached tectorial membrane in mice with C1509G alpha tectorin mutation caused hearing loss, but enhanced electrically evoked otoacoustic emissions. To understand how the mutated cochlea emits sounds, the reticular lamina and basilar membrane vibrations were measured in the electrically stimulated cochlea in this study. The results showed that the electrically evoked basilar membrane vibration decreased dramatically while the reticular lamina vibration and otoacoustic emissions exhibited no significant change in C1509G mutation mice. This result indicates that a functional cochlear amplifier and a normal basilar membrane vibration are not required for the outer hair cell-generated sound to exit the cochlea.

  6. Noninvasive in vivo imaging reveals differences between tectorial membrane and basilar membrane traveling waves in the mouse cochlea.

    Science.gov (United States)

    Lee, Hee Yoon; Raphael, Patrick D; Park, Jesung; Ellerbee, Audrey K; Applegate, Brian E; Oghalai, John S

    2015-03-10

    Sound is encoded within the auditory portion of the inner ear, the cochlea, after propagating down its length as a traveling wave. For over half a century, vibratory measurements to study cochlear traveling waves have been made using invasive approaches such as laser Doppler vibrometry. Although these studies have provided critical information regarding the nonlinear processes within the living cochlea that increase the amplitude of vibration and sharpen frequency tuning, the data have typically been limited to point measurements of basilar membrane vibration. In addition, opening the cochlea may alter its function and affect the findings. Here we describe volumetric optical coherence tomography vibrometry, a technique that overcomes these limitations by providing depth-resolved displacement measurements at 200 kHz inside a 3D volume of tissue with picometer sensitivity. We studied the mouse cochlea by imaging noninvasively through the surrounding bone to measure sound-induced vibrations of the sensory structures in vivo, and report, to our knowledge, the first measures of tectorial membrane vibration within the unopened cochlea. We found that the tectorial membrane sustains traveling wave propagation. Compared with basilar membrane traveling waves, tectorial membrane traveling waves have larger dynamic ranges, sharper frequency tuning, and apically shifted positions of peak vibration. These findings explain discrepancies between previously published basilar membrane vibration and auditory nerve single unit data. Because the tectorial membrane directly overlies the inner hair cell stereociliary bundles, these data provide the most accurate characterization of the stimulus shaping the afferent auditory response available to date.

  7. Development of a Multi-Channel Piezoelectric Acoustic Sensor Based on an Artificial Basilar Membrane

    Directory of Open Access Journals (Sweden)

    Youngdo Jung

    2013-12-01

    Full Text Available In this research, we have developed a multi-channel piezoelectric acoustic sensor (McPAS that mimics the function of the natural basilar membrane capable of separating incoming acoustic signals mechanically by their frequency and generating corresponding electrical signals. The McPAS operates without an external energy source and signal processing unit with a vibrating piezoelectric thin film membrane. The shape of the vibrating membrane was chosen to be trapezoidal such that different locations of membrane have different local resonance frequencies. The length of the membrane is 28 mm and the width of the membrane varies from 1 mm to 8 mm. Multiphysics finite element analysis (FEA was carried out to predict and design the mechanical behaviors and piezoelectric response of the McPAS model. The designed McPAS was fabricated with a MEMS fabrication process based on the simulated results. The fabricated device was tested with a mouth simulator to measure its mechanical and piezoelectrical frequency response with a laser Doppler vibrometer and acoustic signal analyzer. The experimental results show that the as fabricated McPAS can successfully separate incoming acoustic signals within the 2.5 kHz–13.5 kHz range and the maximum electrical signal output upon acoustic signal input of 94 dBSPL was 6.33 mVpp. The performance of the fabricated McPAS coincided well with the designed parameters.

  8. Modeling two-tone suppression and distortion product on basilar membrane

    Science.gov (United States)

    Murakami, Yasuki; Ishimitsu, Shunsuke

    2015-12-01

    This paper reveals mechanisms of two-tone suppression (2TS) and distortion product (DP) on the basilar membrane (BM) using a model. Computational simulation is conducted with an active and nonlinear transmission line model including a nonlinear outer hair cell model that shows compressive property in two dimensionally where two tones are input. To evaluate the cochlear model, over all responses of BM model are used. For simultaneous input pairs, the response is suppressed by a stronger tone, or distorted where levels of a pair are equaled. Cubic distortion produced by a simple nonlinear feedback system including the OHC model appears similar to DPs in the cochlear model. These results suggest that two dimensional property of the OHC and its feedback generate 2TS and DPs. This further suggests the importance of the overall responses for investigating mechanisms of cochlear nonlinearities without fluid coupling in the cochlea.

  9. Behavioral estimates of basilar-membrane input-output in normal-hearing listeners

    DEFF Research Database (Denmark)

    Jepsen, Morten Løve; Dau, Torsten

    2011-01-01

    To characterize human cochlear processing it would be beneficial to behaviorally estimate the basilar membrane (BM) input-output (I/O) function. In recent studies, forward masking has been used to estimate BM compression. In this study, a growth-of-forward-masking (GOM) paradigm (e.g., Oxenham...... function is expected than that obtained for a high-level signal where both masker and signal are processed compressively. The knee point can be estimated at the input level where the GOM slope changes significantly. Data were collected from seven normal - hearing listeners. The method was found to provide...... estimates of the BM I/O function for a wider range of input levels than in previously suggested methods, due to the additional estimates of the knee points....

  10. Effect of different stapes prostheses on the passive vibration of the basilar membrane.

    Science.gov (United States)

    Kwacz, Monika; Marek, Piotr; Borkowski, Paweł; Gambin, Wiktor

    2014-04-01

    The effect of different stapes prostheses on the basilar membrane (BM) motion was determined. To that end, a three dimensional finite element (FE) model of the passive human cochlea was developed. Passive responses of the BM were found based on coupled fluid-structure interactions between the cochlear solid structures and the scala fluids. The passive BM vibrations in normal (healthy) cochlea were compared with vibrations in the cochlea in which a 0.4-mm piston or a proposed new type of prosthesis was implanted. The proposed chamber prosthesis was not experimentally implanted, but only numerically simulated. Design of the new chamber stapes prosthesis is presented for the first time in this paper. The simulation results showed 10-20 dB decrease in BM displacement amplitude in the case of the piston. In contrast, the BM responses in the cochlea with the new prosthesis are higher with respect to the healthy ear. The results obtained in this study are promising for further research to optimize the design of the new chamber stapes prosthesis.

  11. Resultant pressure distribution pattern along the basilar membrane in the spiral shaped cochlea

    CERN Document Server

    Zhang, Yong; Lee, Kong-Ju-Bock; Park, Youngah

    2008-01-01

    Cochlea is an important auditory organ in the inner ear. In most mammals, it is coiled as a spiral. Whether this specific shape influences hearing is still an open problem. By employing a three dimensional fluid model of the cochlea with an idealized geometry, the influence of the spiral geometry of the cochlea is examined. We obtain solutions of the model through a conformal transformation in a long-wave approximation. Our results show that the net pressure acting on the basilar membrane is not uniform along its spanwise direction. Also, it is shown that the location of the maximum of the spanwise pressure difference in the axial direction has a mode dependence. In the simplest pattern, the present result is consistent with the previous theory based on the WKB-like approximation [D. Manoussaki, Phys. Rev. Lett. 96, 088701(2006)]. In this mode, the pressure difference in the spanwise direction is a monotonic function of the distance from the apex and the normal velocity across the channel width is zero. Thus ...

  12. Near field fluid coupling between internal motion of the organ of Corti and the basilar membrane

    Energy Technology Data Exchange (ETDEWEB)

    Elliott, Stephen J.; Ni, Guangjian [Institute of Sound and Vibration Research, University of Southampton, Southampton (United Kingdom)

    2015-12-31

    The pressure distribution in each of the fluid chambers of the cochlea can be decomposed into a 1D, or plane wave, component and a near field component, which decays rapidly away from the excitation point. The transverse motion of the basilar membrane, BM, for example, generates both a 1D pressure field, which couples into the slow wave, and a local near field pressure, proportional to the BM acceleration, that generates an added mass on the BM due to the fluid motion. When the organ of Corti, OC, undergoes internal motion, due for example to outer hair cell activity, this motion will not itself generate any 1D pressure if the OC is incompressible and the BM is constrained not to move volumetrically, and so will not directly couple into the slow wave. This motion will, however, generate a near field pressure, proportional to the OC acceleration, which will act on the OC and thus increases its effective mass. The near field pressure due to this OC motion will also act on the BM, generating a force on the BM proportional to the acceleration of the OC, and thus create a “coupling mass” effect. By reciprocity, this coupling mass is the same as that acting on the OC due to the motion of the BM. This near field fluid coupling is initially observed in a finite element model of a slice of the cochlea. These simulations suggest a simple analytical formulation for the fluid coupling, using higher order beam modes across the width of the cochlear partition. It is well known that the added mass due to the near field pressure dominates the overall mass of the BM, and thus significantly affects the micromechanical dynamics. This work not only quantifies the added mass of the OC due its own motion in the fluid, and shows that this is important, but also demonstrates that the coupling mass effect between the BM and OC significantly affects the dynamics of simple micromechanical models.

  13. Pressure-induced basilar membrane position shifts and the stimulus-evoked potentials in the low-frequency region of the guinea pig cochlea

    NARCIS (Netherlands)

    Fridberger, A; vanMaarseveen, JTPW; Scarfone, E; Ulfendahl, M; Flock, B; Flock, A

    1997-01-01

    We have used the guinea pig isolated temporal bone preparation to investigate changes in the nonlinear properties of the tone-evoked cochlear potentials during reversible step displacements of the basilar membrane towards either the scala tympani or the scala vestibuli. The position shifts were prod

  14. Estimating the basilar-membrane input-output function in normal-hearing and hearing-impaired listeners

    DEFF Research Database (Denmark)

    Jepsen, Morten Løve; Dau, Torsten

    To partly characterize the function of cochlear processing in humans, the basilar membrane (BM) input-output function can be estimated. In recent studies, forward masking has been used to estimate BM compression. If an on-frequency masker is processed compressively, while an off-frequency masker...... processing at medium levels. If a signal can be masked by a low-level on-frequency masker such that signal and masker fall in the linear region of the I/O-function, then a steeper GOM function is expected. The knee-point can then be estimated in the input level region where the GOM changes significantly...... higher input levels and compression was similar to that of NH listeners....

  15. Traumatic basilar pseudoaneurysm with a basilar-cavernous arteriovenous fistula

    Energy Technology Data Exchange (ETDEWEB)

    Connor, S.E.J.; Deasy, N.P.; Jeffree, M.A. [Dept. of Neuroradiology, King' s Coll. Hospital, London (United Kingdom); Martin, A.J.; Strong, A.J. [Dept. of Neurosurgery, King' s Coll. Hospital, London (United Kingdom)

    2001-03-01

    A traumatic pseudoaneurysm of the basilar artery with a basilar-cavernous sinus arteriovenous fistula was diagnosed in a 12-year-old girl using CT, MRI and angiography. It was successfully treated by coil embolisation. We speculate on the mode of formation of this rare traumatic lesion. (orig.)

  16. 一氧化氮合酶阻断剂对豚鼠耳蜗基底膜振动速度的影响%Effect of nitric oxide synthase blockade on basilar membrane velocity in guinea pigs cochlea

    Institute of Scientific and Technical Information of China (English)

    郭梦和; 黄以乐

    1999-01-01

    目的:观察N-甲基-左旋精氨酸(L-NNA)对基底膜振动速度(velocity of basilar membrane vibration, BMV)的影响,了解一氧化氮(NO)对耳蜗外毛细胞(cochlear outer hair cells, COHCs)的作用.方法:杂色豚鼠25只,麻醉、手术准备后用1.6 mmol/L的L-NNA 8 μL行耳蜗底圈鼓阶内灌注,测试BMV、听神经复合动作电位(cAP)、蜗内电位(EP),记录用直流电脉冲诱发的BMV.结果:蜗内灌注L-NNA后,BMV大约提高了3倍,耳蜗微音器电位振幅略有下降,而EP无明显变化.这一现象只出现在耳蜗灵敏度仅有轻微下降情况下,正常听敏度耳蜗或耳蜗功能严重损伤时BMV无提高作用.结论:NO可能促使耳蜗的声损伤加重,L-NNA可阻断NO的合成,从而起到保护耳蜗的作用.

  17. Oculomotor Paresis and Basilar Aneurysm

    OpenAIRE

    J Gordon Millichap

    1992-01-01

    The clinical and pathologic findings in a 10 month old girl with congenital heart diseasewho died after rupture of a congenital distal basilar artery aneurysm are reported from the University of Connecticut Health Center, Farmington, CT and the Children’s Hospital of Philadelphia, PA.

  18. Hair cell force generation does not amplify or tune vibrations within the chicken basilar papilla.

    Science.gov (United States)

    Xia, Anping; Liu, Xiaofang; Raphael, Patrick D; Applegate, Brian E; Oghalai, John S

    2016-10-31

    Frequency tuning within the auditory papilla of most non-mammalian species is electrical, deriving from ion-channel resonance within their sensory hair cells. In contrast, tuning within the mammalian cochlea is mechanical, stemming from active mechanisms within outer hair cells that amplify the basilar membrane travelling wave. Interestingly, hair cells in the avian basilar papilla demonstrate both electrical resonance and force-generation, making it unclear which mechanism creates sharp frequency tuning. Here, we measured sound-induced vibrations within the apical half of the chicken basilar papilla in vivo and found broadly-tuned travelling waves that were not amplified. However, distortion products were found in live but not dead chickens. These findings support the idea that avian hair cells do produce force, but that their effects on vibration are small and do not sharpen tuning. Therefore, frequency tuning within the apical avian basilar papilla is not mechanical, and likely derives from hair cell electrical resonance.

  19. Electroencephalograms in basilar artery migraine.

    Science.gov (United States)

    Parain, D; Samson-Dollfus, D

    1984-11-01

    Nine cases of 'basilar artery migraine' (BAM) have been recorded. In 8 cases, excess of beta activity was observed during the attacks and disappeared in less than 3 days. The inter-ictal EEGs were normal. Drug ingestion was excluded each time. These EEG patterns are different from those which have been reported in the literature, i.e., transitory posterior abnormal slow waves. However, case no.1 is in agreement with the literature. The expression 'BAM' probably covers different syndromes which are further discussed.

  20. Basilar invagination, Chiari malformation, syringomyelia: A review

    Directory of Open Access Journals (Sweden)

    Goel Atul

    2009-01-01

    Full Text Available Institute and personal experience (over 25 years of basilar invagination was reviewed. The database of the department included 3300 patients with craniovertebral junction pathology from the year 1951 till date. Patients with basilar invagination were categorized into two groups based on the presence (Group A or absence (Group B of clinical and radiological evidence of instability of the craniovertebral junction. Standard radiological parameters described by Chamberlain were used to assess the instability of the craniovertebral junction. The pathogenesis and clinical features in patients with Group A basilar invagination appeared to be related to mechanical instability, whereas it appeared to be secondary to embryonic dysgenesis in patients with Group B basilar invagination. Treatment by facetal distraction and direct lateral mass fixation can result in restoration of craniovertebral and cervical alignment in patients with Group A basilar invagination. Such a treatment can circumvent the need for transoral or posterior fossa decompression surgery. Foramen magnum bone decompression appears to be a rational surgical treatment for patients having Group B basilar invagination. The division of patients with basilar invagination on the basis of presence or absence of instability provides insight into the pathogenesis of the anomaly and a basis for rational surgical treatment.

  1. Hipnoticos corticales y basilares y acciones anticonvulsivantes

    OpenAIRE

    Carlos Gutiérrez-Noriega

    2013-01-01

    Se estudian las diferencias de los hipnóticos corticales y basilares desde el punto de vista de sus acciones anticonvulsivantes. Los resultados son los siguientes: 1. Los hipnóticos del grupo basilar (barbitúrico y uretano) poseen un poder anticonvulsivante considerablemente mayor que los hipnóticos del grupo cortical (alcoholes, aldehidos, bromuros, éter), con excepción del sulfato de magnesia, clasificado en el grupo subcortical, que tiene muy poca acción anticonvulsivante. 2. Algunos hipnó...

  2. Anastomose carótido-basilar

    Directory of Open Access Journals (Sweden)

    Ricardo Reixach-Granés

    1965-09-01

    Full Text Available O autor relata um caso de anastomose carótido-basilar por persistência da artéria trigeminal, demonstrado angiogràficamente. O paciente apresentou hemiplegia súbita e era portador de transtornos mentais de tipo deficitário. A pneumencefalografia evidenciou atrofia do parênquima cerebral do lado da anomalia.

  3. Mechanical thrombectomy in basilar artery thrombosis

    DEFF Research Database (Denmark)

    Fesl, Gunther; Holtmannspoetter, Markus; Patzig, Maximilian;

    2014-01-01

    PURPOSE: Multiple endovascular devices have been used for mechanical thrombectomy (MT) in basilar artery occlusion (BAO) for >10 years. Based on a single-center experience during the course of one decade, we present data on safety and efficacy of previous MT devices compared with modern stent ret...

  4. Basilar artery migraine and reversible imaging abnormalities.

    Science.gov (United States)

    Maytal, J; Libman, R B; Lustrin, E S

    1998-01-01

    We report a case of a basilar artery migraine in a 17-year-old boy with transient CT and MR abnormalities after each of two migraine episodes. A repeat MR study 6 months after the last event showed complete resolution of the lesion. Transient abnormalities on brain images similar to those shown in our case have been reported in patients with migraine and other neurologic conditions and are most likely related to cerebral vasogenic edema.

  5. Endovascular treatment for ruptured basilar apex aneurysm

    Directory of Open Access Journals (Sweden)

    Sheng LI

    2011-12-01

    Full Text Available Objective The present study aims to prove the effectiveness and safety of endovascular interventional therapy for ruptured basilar apex aneurysm.Methods The imaging data,methods of endovascular treatment,and clinical results of 12 patients suffering from ruptured basilar apex aneurysms from January 2001 to December 2009 were retrospectively analyzed.The 12 patients were composed of 5 males and 7 females,and their ages ranged from 21 years to 58 years.Results Nine patients suffered from narrow-necked aneurysms,which were directly embolized,and the other three suffered from wide-necked aneurysms,which were embolized using a microstent.Eight aneurysms were completely embolized,and the other four were partly embolized.No rebleeding occurred within the follow-up period of 12 months to 36 months,and all patients recovered well without neurological defects.Conclusions Therefore,endovascular treatment for ruptured basilar apex aneurysm is a semi-invasive,safe,and effective method.

  6. Neurofibromatosis, stroke and basilar impression: case report

    Directory of Open Access Journals (Sweden)

    PIOVESAN ELCIO JULIATO

    1999-01-01

    Full Text Available Neurofibromatosis type 1 (NF1 can virtually affect any organ, presenting most frequently with "cafe au lait" spots and neurofibromas. Vasculopathy is a known complication of NF1, but cerebrovascular disease is rare. We report the case of a 51-year-old man admitted to the hospital with a history of stroke four months before admission. On physical examination, he presented various "cafe au lait" spots and cutaneous neurofibromas. Neurologic examination demonstrated right-sided facial paralysis, right-sided hemiplegia, and aphasia. Computed tomography scan of head showed hypodense areas in the basal ganglia and centrum semiovale. Radiographs of cranium and cervical spine showed basilar impression. Angiography revealed complete occlusion of both vertebral and left internal carotid arteries, and partial stenosis of the right internal carotid artery. A large network of collateral vessels was present (moyamoya syndrome. It is an uncommon case of occlusive cerebrovascular disease associated with NF1, since most cases described in the literature are in young people, and tend to spare the posterior cerebral circulation. Basilar impression associated with this case may be considered a pure coincidence, but rare cases of basilar impression and NF1 have been described.

  7. Hipnoticos corticales y basilares y acciones anticonvulsivantes

    Directory of Open Access Journals (Sweden)

    Carlos Gutiérrez-Noriega

    1943-06-01

    Full Text Available Se estudian las diferencias de los hipnóticos corticales y basilares desde el punto de vista de sus acciones anticonvulsivantes. Los resultados son los siguientes: 1. Los hipnóticos del grupo basilar (barbitúrico y uretano poseen un poder anticonvulsivante considerablemente mayor que los hipnóticos del grupo cortical (alcoholes, aldehidos, bromuros, éter, con excepción del sulfato de magnesia, clasificado en el grupo subcortical, que tiene muy poca acción anticonvulsivante. 2. Algunos hipnóticos del grupo cortical (cloralosa disminuyen notablemente a dosis narcótica el umbral para las convulsiones clónicas, producidas por el cardiazol, coramina y estricnina; pero aumentan el umbral para las convulsiones tónicas. Estos hipnóticos actúan paradójicamente, como anticonvulsivantes y como sinergistas de los convulsivantes. 3. El sinergismo de cardiazol y estricnina para producir convulsiones clónicas es mucho más notable durante la narcosis por cloralosa que en el animal no anestesiado. 4. Existen significativas diferencias cualitativas y cuantitativas entre las convulsiones del animal no anestesiado y las convulsiones del animal durante la narcosis por cloralosa. En este último caso no se produce la reacción tónica, las reacciones neurovegetativas son más débiles, pero la duración de las convulsiones clónicas es considerablemente mayer. 5. Las diferencias de actividad anticonvulsivante observadas entre los dos grupos de hipnóticos, no pueden ser tomadas como prueba de la clasificación topográfica (córtico-basilar. Al contrario, sugieren que algunos hipnóticos del grupo cortical deben su típica manera de actuar a una acción estimulante tanto sobre la corteza cerebral como sobre los centros subcorticales. Se discute la posibilidad de que el sistema internuncial sea el que principalmente se estimula. Así, mientras que en la narcosis de tipo barbitúrico disminuye la excitabilidad de todo el sistema nervioso de relaci

  8. Basilar artery of the capybara (Hydrochaeris hydrochaeris): an ultrastructural study.

    Science.gov (United States)

    Islam, S; Ribeiro, A A C M; Loesch, A

    2004-04-01

    The present study investigated the ultrastructural features of the basilar artery of the largest rodent species, the capybara. The study suggests that the general ultrastructural morphological organization of the basilar artery of the capybara is similar to that of small rodents. However, there are some exceptions. The basilar artery of the capybara contains a subpopulation of 'granular' vascular smooth muscle cells resembling monocytes and/or macrophages. The possibility cannot be excluded that the presence of these cells reflects the remodelling processes of the artery due to animal maturation and the regression of the internal carotid artery. To clarify this issue, more systemic studies are required involving capybaras of various ages.

  9. Trigeminal neuralgia secondary to basilar impression: A case report

    Science.gov (United States)

    de Almeida Holanda, Maurus Marques; Pereira Neto, Normando Guedes; de Moura Peixoto, Gustavo; Pinheiro Santos, Rayan Haquim

    2015-01-01

    We report a rare case of trigeminal neuralgia. A 23-year-old woman with a history of 1 year of typical trigeminal neuralgia manifested the characteristics of basilar impression. Magnetic resonance imaging (MRI) demonstrated basilar impression, deformity of the posterior fossa with asymmetry of petrous bone, and compression of medulla oblongata in the topography of the odontoid apophysis. The operation was performed through a suboccipital craniectomy. The neuralgia disappeared after surgery and remains completely resolved until today. This is the second reported case of trigeminal neuralgia in a patient with basilar impression in Brazil. PMID:25972713

  10. Effect of acupuncture at Yifeng, Ermen and Zhongzhu acupoints on pathohistological and morphological changes of basilar membrane in guinea pigs with drug poisoning auditory injury%针刺翳风、耳门、中渚穴对药物中毒性听力损害豚鼠耳蜗基底膜病理组织形态的影响

    Institute of Scientific and Technical Information of China (English)

    付平; 郭长青; 耿恩广

    2006-01-01

    BACKGROUND: At present, there is no ideal way to treat auditory injury, and acupuncture would become an effective method to prevent and cure drug auditory injury.OBJECTIVE: To observe the effect of acupuncture at Yifeng, Ermen and Zhongzhu acupoints on improving histopathologic form of basilar membrane of guinea pig with drug poisoning auditory injury.DESIGN: Completely randomized design on the basis of experiment al animals.SETTING: Department of Neurology, Xuanwu Hospital, Capital University of Medical Sciences.MATERIALS: A total of 45 white male guinea pigs with normal Preyer's reflex were selected in this study. Guinea pigs were 3-4 months old, of general grade and weighted from 250 g to 300 g. All guinea pigs were randomly divided into 5 groups: normal group, model group, Yifeng group, Ermen group and Zhongzhu group with 9 in each group.METHODS: The experiment was completed at the Laboratory of College of Acupuncture and Moxibustion Affiliated to Beijing University of Traditional Chinese Medicine from April to July 2002. ① Normal group: Guinea pigs were fed with normal feed. Other four groups: Guinea pigs were injected into muscle with 80 mg/kg gentamycin for 20 days, and guinea pigs in Yifeng group, Ermen group and Zhongzhu group were acupunctured at corresponding acupoints at the same time. Before acupuncture, guinea pigs were fixed and rapidly acupunctured into subcutaneous tissue with stainless steel needle sized 0.35 mm × 25 mm. The needle was inserted about 10 mm. According to uniform reinforcing-reducing method, the needle was thrusted once every 10 minutes with each for 30 seconds and retained for 30 minutes. The course was 20 days. ② Basilar membrane of guinea pigs was established. Amount of hair cell was calculated under optic microscope (×200) to record deletion amount of hair cell and observe activity of succinic dehydrogenase; meanwhile, ultrastructure of hair cells was observed with transmission electron microscope (×5 000). Measurement

  11. Delayed onset of fatal basilar thrombotic embolus after whiplash injury

    DEFF Research Database (Denmark)

    Viktrup, L; Knudsen, G M; Hansen, S H

    1995-01-01

    BACKGROUND: Whiplash injuries are generally seen after rear-end rather than frontal car collisions. Previous reports have documented death up to 8 days after serious whiplash injury. We report a case of lethal basilar thrombotic embolus that occurred 2 months after the patient's injury...... in a collision. CASE DESCRIPTION: After whiplash trauma in a car accident, a 50-year-old taxi driver suffered from headache and episodic visual disturbances. Two months after the accident he suddenly lost consciousness and was admitted to the hospital. A CT scan performed at that time was indicative of basilar...... thrombosis. The patient died 3 days later. The autopsy revealed a thrombosis in the right vertebral artery and a thrombotic embolus in the basilar artery. Microscopically, a lesion of the right vertebral artery was found at the level of the atlantoaxial joint. CONCLUSIONS: We conclude that the whiplash...

  12. Microscopic anatomy of the human vertebro-basilar system

    Directory of Open Access Journals (Sweden)

    Renato P. Chopard

    1991-12-01

    Full Text Available Concerning the structure of connective-muscular components the authors studied the walls of the terminal segments of the vertebral arteries as well as the basilar artery, utilizing the following staining methods: Azan modified by Heideinheim, Weigert's resorcin-fuchsin, and Weigert modified by van Gieson. It was established that wall of the vertebro-basilar system exhibits a mixed structure, muscular and elastic, by means of which the vessels are adjusted to the specific blood circulation conditions. Thus, vertebral arteries show in the most external layer of tunica media an evident external elastic lamina. In contrast, in the basilar artery the elastic tissue is localized mainly in the tunica media, and is distributed heterogeneously. In its caudal segment the elastic fibers are situated in the most internal layer of tunica media, and in the cranial segment the elastic component is homogenously distributed in the whole of tunica media.

  13. Primary stenting as emergency therapy in acute basilar artery occlusion

    Energy Technology Data Exchange (ETDEWEB)

    Spreer, Joachim; Arnold, Sebastian; Klisch, Joachim; Schumacher, Martin [Section of Neuroradiology, University Hospital Freiburg, Breisacher Strasse 64, 79106 Freiburg (Germany); Els, Thomas; Hetzel, Andreas; Huppertz, Hans-Juergen; Oehm, Eckhardt [Department of Neurology, University Hospital Freiburg, Freiburg (Germany)

    2002-09-01

    In three patients with acute occlusion of the basilar artery intra-arterial fibrinolysis resulted in only partial recanalization and revealed severe stenosis as the underlying cause. Application of micro-stents without previous dilatation resulted in vessel re-opening. Two patients had an excellent clinical outcome. One patient died 10 days after the stroke due to brainstem infarction. Emergency primary stent application may improve the outcome in acute basilar artery occlusion, if intra-arterial thrombolysis fails to re-establish a sufficient flow. (orig.)

  14. Basilar artery aneurysm case presented with neck pain

    Directory of Open Access Journals (Sweden)

    Uygar Utku

    2013-04-01

    Full Text Available Neck pain related with disorders of the brain and neck vascular structures is not rare but importance was attached to a condition that is often overlooked. Tension as a sudden onset, radiating to the nape, the neck pain becomes unbearable and within seconds the raging 51-year-old female patient with aneurysm at the distal end of basilar artery was found. Case, the only sign of neck pain with unruptured basilar artery aneurysm is presented in terms of raising awareness on the subject.

  15. Middle meningeal artery arising from the basilar artery.

    Science.gov (United States)

    Salem, Mohamed M; Fusco, Matthew R; Dolati, Parviz; Reddy, Arra S; Gross, Bradley A; Ogilvy, Christopher S; Thomas, Ajith J

    2014-12-01

    Various anomalies for the origin of the middle meningeal artery (MMA) have been described in the literature. However, origin of the MMA from the basilar trunk is an extremely rare variant. We report on a 54-year-old female who presented with frequent headaches; magnetic resonance imaging showed a right parietal meningioma. The abnormal origin of the middle meningeal artery from the basilar artery was diagnosed by angiography performed for preoperative embolization of the tumor. We report on the case with a review of the embryologic basis, possible explanations for this aberrant origin, and its clinical implications.

  16. Alterations of voltage-dependent calcium channel currents in basilar artery smooth muscle cells at early stage of subarachnoid hemorrhage in a rabbit model.

    Directory of Open Access Journals (Sweden)

    Xianqing Shi

    Full Text Available OBJECTIVE: To investigate the changes in the currents of voltage-dependent calcium channels (VDCCs in smooth muscle cells of basilar artery in a rabbit model of subarachnoid hemorrhage (SAH. METHODS: New Zealand white rabbits were randomly divided into five groups: sham (C, normal (N, 24 hours (S1, 48 hours (S2 and 72 hours (S3 after SAH. Non-heparinized autologous arterial blood (1 ml/kg was injected into the cisterna magna to create SAH after intravenous anesthesia, and 1 ml/kg of saline was injected into cisterna magna in the sham group. Rabbits in group N received no injections. Basilar artery in S1, S2, S3 group were isolated at 24, 48, 72 hours after SAH. Basilar artery in group C was isolated at 72 hours after physiological saline injection. Basilar artery smooth muscle cells were isolated for all groups. Whole-cell patch-clamp technique was utilized to record cell membrane capacitance and VDCCs currents. The VDCCs antagonist nifedipine was added to the bath solution to block the Ca(++ channels currents. RESULTS: There were no significant differences in the number of cells isolated, the cell size and membrane capacitance among all the five groups. VDCC currents in the S1-S3 groups had higher amplitudes than those in control and sham groups. The significant change of current amplitude was observed at 72 hours after SAH, which was higher than those of 24 and 48 hours. The VDCCs were shown to expression in human artery smooth muscle cells. CONCLUSIONS: The changes of activation characteristics and voltage-current relationship at 72 hours after SAH might be an important event which leads to a series of molecular events in the microenvironment of the basilar artery smooth muscle cells. This may be the key time point for potential therapeutic intervention against subarachnoid hemorrhage.

  17. Intraorbital ophthalmic artery aneurysm associated with basilar tip saccular aneurysm

    Energy Technology Data Exchange (ETDEWEB)

    Dehdashti, A.R.; Tribolet, N. de [Department of Neurosurgery, HUG, Geneva (Switzerland); Safran, A.B. [Department of Ophthalmology, HUG, Geneva (Switzerland); Martin, J.B.; Ruefenacht, D.A. [Division of Neuroradiology, HUG, Geneva (Switzerland)

    2002-07-01

    We present a rare case of intraorbital ophthalmic artery aneurysm found incidentally, together with a ruptured aneurysm of the tip of the basilar artery. The intraorbital aneurysm was asymptomatic, and no treatment was offered. Angiographic control was recommended to detect any progression. Treatment may be indicated for documented enlargement or significant mass effect of the aneurysm. (orig.)

  18. Basilar artery thrombosis in the setting of antiphospholipid syndrome.

    Science.gov (United States)

    Saad, Amin F; Nickell, Larry T; Heithaus, R Evans; Shamim, Sadat A; Opatowsky, Michael J; Layton, Kennith F

    2014-07-01

    Antiphospholipid syndrome is an autoimmune disorder characterized by arterial or venous thrombosis, recurrent first-trimester pregnancy loss, and multiple additional clinical manifestations. We describe a man with severe atherosclerotic basilar artery stenosis and superimposed in situ thrombus who was found to have antiphospholipid syndrome.

  19. Relaxation effect of abacavir on rat basilar arteries.

    Directory of Open Access Journals (Sweden)

    Rachel Wai Sum Li

    Full Text Available The use of abacavir has been linked with increased cardiovascular risk in patients with human immunodeficiency virus infection; however, the mechanism involved remains unclear. We hypothesize that abacavir may impair endothelial function. In addition, based on the structural similarity between abacavir and adenosine, we propose that abacavir may affect vascular contractility through endogenous adenosine release or adenosine receptors in blood vessels.The relaxation effect of abacavir on rat basilar arteries was studied using the myograph technique. Cyclic GMP and AMP levels were measured by immunoassay. The effects of abacavir on nucleoside transporters were studied using radiolabeled nucleoside uptake experiments. Ecto-5' nucleotidase activity was determined by measuring the generation of inorganic phosphate using adenosine monophosphate as the substrate.Abacavir induced the relaxation of rat basilar arteries in a concentration-dependent manner. This relaxation was abolished when endothelium was removed. In addition, the relaxation was diminished by the nitric oxide synthase inhibitor, L-NAME, the guanylyl cyclase inhibitor, ODQ, and the protein kinase G inhibitor, KT5820. Abacavir also increased the cGMP level in rat basilar arteries. Abacavir-induced relaxation was also abolished by adenosine A2 receptor blockers. However, abacavir had no effect on ecto-5' nucleotidase and nucleoside transporters. Short-term and long-term treatment of abacavir did not affect acetylcholine-induced relaxation in rat basilar arteries.Abacavir induces acute endothelium-dependent relaxation of rat basilar arteries, probably through the activation of adenosine A2 receptors in endothelial cells, which subsequently leads to the release of nitric oxide, resulting in activation of the cyclic guanosine monophosphate/protein kinase G-dependent pathway in vascular smooth muscle cells. It is speculated that abacavir-induced cardiovascular risk may not be related to

  20. [Basilar ectasia and stroke: clinical aspects of 21 cases].

    Science.gov (United States)

    de Oliveira, R de M; Cardeal, J O; Lima, J G

    1997-09-01

    Ectasia of the basilar artery (EB) occurs when its diameter is greater than normal along all or part of its course, and/or when it is abnormally tortuous. EB may cause cranial nerve dysfunction, ischemic stroke or subarachnoid hemorrhage, pseudotumor or hydrocephalus. We tried to describe cases of stroke associated with EB, analyze its frequency, clinical aspects, and the mechanisms involved in different forms of its presentation. We found 21 patients with stroke and EB. The association between EB and stroke was more prevalent in males over the age of fifty. Main symptoms were hemiparesia, cranial nerves dysfunction, and cerebellar ataxia. Cerebral infarcts associated with EB were due to different mechanisms: arterial thrombosis, artery-to-artery embolism, mass effect with angulation and obstruction of the vertebral and basilar branches.

  1. 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...

  2. A cadaveric study of the endoscopic endonasal transclival approach to the basilar artery.

    Science.gov (United States)

    Lai, Leon T; Morgan, Michael K; Chin, David C W; Snidvongs, Kornkiat; Huang, June X Z; Malek, Joanne; Lam, Matthew; McLachlan, Rohan; Harvey, Richard J

    2013-04-01

    The anterior transclival route to basilar artery aneurysms is not widely performed. The objective of this study was to carry out a feasibility assessment of the transclival approach to basilar aneurysms with advanced endonasal techniques on 11 cadaver heads. Clival dura was exposed from the sella to the foramen magnum between the paraclival segments of the internal carotid arteries (ICA) laterally. An inverted dural "U" flap was reflected inferiorly to expose the basilar artery. The maximal dimensions from operative measurements were recorded. Surgical manoeuvrability of multiple instruments and the proficiency to place proximal and distal vascular clips were evaluated. The mean operative depth (± standard deviation), measured from the anterior choanae to the basilar artery, was 110±6mm. The lateral corridors were limited distally by the medial pterygoids (mean width 21±2mm) and paraclival ICA (mean width 20±2mm). The mean transclival craniectomy dimensions were 19±2mm (width) and 23±4mm (height). Exposure of the basilar-anterior inferior cerebellar artery junction, superior cerebellar artery, and the basilar caput were possible in 100%, 91%, and 64% of instances, respectively. Placements of proximal and distal aneurysm clips were achieved in all instances. Based on our findings, the transclival endoscopic endonasal surgery approach provides excellent visualisation of the basilar artery. Clip application and manoeuvrability of instruments was considered adequate for basilar aneurysm surgery. Surgical skills and instrumentation to control significant haemorrhage can potentially limit the clinical applicability of this technique.

  3. Vertebral artery stenosis in the Basilar Artery International Cooperation Study (BASICS): prevalence and outcome

    NARCIS (Netherlands)

    Compter, A.; Hoeven, E.J. van der; Worp, H.B. van der; Vos, J.A.; Weimar, C.; Rueckert, C.M.; Kappelle, L.J.; Algra, A.; Schonewille, W.J.; Leeuw, F.E. de

    2015-01-01

    We assessed the prevalence of vertebral artery (VA) stenosis or occlusion and its influence on outcome in patients with acute basilar artery occlusion (BAO). We studied 141 patients with acute BAO enrolled in the Basilar Artery International Cooperation Study (BASICS) registry of whom baseline CT an

  4. Vertebral artery stenosis in the Basilar Artery International Cooperation Study (BASICS) : prevalence and outcome

    NARCIS (Netherlands)

    Compter, Annette; van der Hoeven, Erik J R J; van der Worp, H. Bart; Vos, Jan Albert; Weimar, Christian; Rueckert, Christina M.; Kappelle, L. Jaap; Algra, Ale; Schonewille, Wouter J.; Vergouwen, MD

    2015-01-01

    We assessed the prevalence of vertebral artery (VA) stenosis or occlusion and its influence on outcome in patients with acute basilar artery occlusion (BAO). We studied 141 patients with acute BAO enrolled in the Basilar Artery International Cooperation Study (BASICS) registry of whom baseline CT an

  5. Hemifacial spasm in a patient with basilar artery dolichoectasia caused by uncontrolled hypertension

    Directory of Open Access Journals (Sweden)

    Gordon S. Crabtree

    2016-10-01

    Full Text Available A 47-year-old male presented with a 2-year history of hemifacial spasm. Magnetic resonance imaging performed showed his tortuous basilar artery with nerve compression, and the patient was treated conservatively with botulinum toxin injections with complete resolution of symptoms. This rare disease was caused by his long history of hypertension, which led to his major basilar artery dolichoectasia.

  6. Basilar artery occlusion: Prognostic signs of severity on computed tomography

    Energy Technology Data Exchange (ETDEWEB)

    Poletti, Pierre-Alexandre, E-mail: pierre-alexandre.poletti@hcuge.ch [Service of Radiology, University Hospital of Geneva (Switzerland); Pereira, Vitor Mendes [Service of Neuroradiology, University Hospital of Geneva, 4 rue Gabrielle-Perret-Gentil, 1211 Geneva (Switzerland); Department of Medical Imaging, University of Toronto (Canada); Department of Surgery, University of Toronto (Canada); Lovblad, Karl-Olof [Service of Neuroradiology, University Hospital of Geneva, 4 rue Gabrielle-Perret-Gentil, 1211 Geneva (Switzerland); Canel, Lucie [Service of Radiology, University Hospital of Geneva (Switzerland); Sztajzel, Roman [Service of Neurology, University Hospital of Geneva, 4 rue Gabrielle-Perret-Gentil, 1211 Geneva (Switzerland); Becker, Minerva [Service of Radiology, University Hospital of Geneva (Switzerland); Perneger, Thomas [Division of Clinical Epidemiology, University Hospital of Geneva, 4 rue Gabrielle-Perret-Gentil, 1211 Geneva (Switzerland); Platon, Alexandra [Service of Radiology, University Hospital of Geneva (Switzerland)

    2015-07-15

    Highlights: • The main CT signs associated with basilar artery occlusion were analyzed. • CT sign of acute ischemic lesion is significantly associated with a bad outcome. • The site of the basilar artery occlusion is not associated to the patients’ outcome. - Abstract: Purpose: To determine the computed tomography (CT) signs that are predictive of the clinical outcome of basilar artery occlusion (BAO). Materials and methods: The study population consisted in 37 patients (14 women, 23 men, mean age: 63 years), admitted with onset of neurological deficit, starting 1–72 h prior to admission, who were diagnosed with BAO on the basis of a CT examination with intravenous contrast agent. The following signs were collected on CT scans performed on admission: clot density on noncontrast images, clot length, and clot location, as well as the presence of acute ischemic lesions. The results were compared against the modified Rankin Scale (mRS) score of patients at 3 months, favorable clinical outcome being defined as a mRS score ≤3. Results: The clinical outcome was favorable in 13 (35%) of the 37 patients and unfavorable in 24 (65%). Signs of acute ischemia were visible in 13 of the 24 patients with unfavorable outcome but in none of the 13 patients with favorable outcome (p < 0.001). None of the other CT signs analyzed were significantly correlated with clinical prognosis. Conclusion: Of all the CT signs analyzed, only the presence of signs of acute ischemia on the admission CT of patients with BAO was associated with poor prognosis.

  7. Surgical treatment of Chiari malformation complicated with basilar impression

    Directory of Open Access Journals (Sweden)

    Yuan MA

    2011-02-01

    Full Text Available Objective To evaluate the therapeutic effect of small craniotomic posterior fossa decompression combined with occipital-cervical bone graft fusion and internal fixation on Chiari malformation complicated with basilar impression.Methods The clinical data of 16 cases(7 males and 9 females,aged 17 to 65 years,mean 36.4 of Chiari malformation complicated with basilar impression from 2006 to 2010 were retrospectively analyzed.The diagnoses for all the patients were confirmed by radiology.Small craniotomic posterior fossa decompression was performed in all patients,cerebellar tonsils were resected,and then one-stage occipital-cervical bone graft fusion using autogenous iliac bone and internal wiring fixation were performed.Neck support was used for 3 months after surgery.Results Symptoms were significantly improved in all cases after surgical operation.No patient died or infected.Cerebrospinal fluid leakage was found at draining site in one case.Transient pain of scapular and chest was found in one case and disappeared spontaneously.A 6-months follow-up showed that 6 patients were cured,9 improved and 1 unchanged according to Symon and Lavender standard.Postoperative MRI showed the reconstructed cisterna magna was clear in all patients,no cerebellar ptosis was found,and the occipital-cervical graft bone was fused.Conclusion In patients with Chiari malformation complicated with basilar impression,small craniotomic posterior fossa decompression combined with one-stage occipital-cervical bone graft fusion and internal wiring fixation has a clear and definite effect,it can increase the volume of posterior fossa and alleviate the ventral brain stem compression simultaneously,and reconstruct the stability of cranio-cervical junction.

  8. Segmental myoclonus and basilar artery giant aneurysm case report

    Directory of Open Access Journals (Sweden)

    J. Pitágoras de Mattos

    1992-12-01

    Full Text Available A 70 years-old man was admitted at our hospital because of unstable angina pectoris. He had essential hypertension and right hemiplegia from a ischemic stroke two years before admission. On neurologic examination, it was found mental disorientation, unstable emotionality, right spastic hemiparesis with right Babinski sign, and segmental myoclonus affecting the superior lip and the palate (palatal nystagmus on the right side. On the CT scan, a giant aneurysm of the basilar artery was detected. We conclude that the segmental myoclonus could be explained by ischemic lesions in the Guillain - Mollaret triangle.

  9. Stent-based mechanical thrombectomy in acute basilar artery occlusion.

    Science.gov (United States)

    Cohen, José E; Leker, Ronen R; Moscovici, Samuel; Attia, Moshe; Itshayek, Eyal

    2011-12-01

    Stent-based mechanical thrombectomy was recently proposed as an effective alternative to other mechanical techniques to achieve recanalization of large-vessel embolic occlusions in the anterior circulation. To our knowledge, there are no reports of the use of this technique in acute basilar artery occlusion (ABAO). We present a patient with complete endovascular recanalization of ABAO using a stent-based thrombectomy technique. Advantages and limitations of this technique in the management of ABAO are discussed. The stent-thrombectomy technique is promising, and will need further evaluation in posterior circulation stroke.

  10. Bilateral hypoplasia of the internal carotid arteries with basilar aneurysm

    Energy Technology Data Exchange (ETDEWEB)

    Briganti, F.; Tortora, F.; Elefante, A. [Universita di Napoli Federico II, Dipartimento di Scienze Neurologiche, Cattedra di Neuroradiologia, 80131, Napoli (Italy); Maiuri, F. [Universita di Napoli Federico II, Department of Neurological Sciences, Neurosurgery Service, Napoli (Italy)

    2004-10-01

    We report a rare case of bilateral hypoplasia of the internal carotid arteries with an associated aneurysm of the basilar tip, studied by CT angiography, MR angiography and digital angiography. The patient became symptomatic with an episode of loss of consciousness, likely due to reduced blood perfusion. The other 20 reported cases of bilateral carotid hypoplasia (only four of which with an associated aneurysm) are reviewed. The findings of noninvasive procedures (including narrowing of the carotid canals on CT) may lead to a correct diagnosis before angiography is performed; they may also help to differentiate angiographic narrowing of the hypoplastic internal carotids from the string sign often observed in some acquired conditions. (orig.)

  11. CNS fungal meningitis to the "Top of the basilar"

    Institute of Scientific and Technical Information of China (English)

    Logan CS; Kirschner RC; Simonds GR

    2013-01-01

    Central nervous system(CNS) infections are a rare complication of epidural steroid injections and without strong clinical suspicion, fungal organisms may be overlooked among the long differential of causes of meningitis.Rare sequela of fungal meningitis is the development of stroke.To our knowledge, we present the first case of post epidural steroid injection(ESI) fungal meningitis leading toa basilar artery stroke, otherwise known as“top of the basilar” syndrome.We present a49-year-old female with a history ofESIs who presented to the emergency department with headache, neck stiffness, and abdominal pain.She was discharged after her labs and symptoms were deemed inconsistent with meningitis.She was eventually admitted and twelve days after her originalED visit, she was diagnosed with meningitis and started on anti-fungal treatment.She was discharged88 days later but was readmitted due to left sided weakness and mental status changes.She quickly lost motor and bulbar functions.AnMRA showed diminished distal flow through the basilar artery, suggesting near complete occlusion.Although appropriate long term anti-fungal treatment was started, the patient still succumbed to a rare vascular event.Physicians who are treating patients forESI meningitis should be aware of the potential for vasculitic and encephalitic complications.

  12. Local lysis in acute basilar artery occlusions: a case report

    Energy Technology Data Exchange (ETDEWEB)

    Karnik, R.; Perneczky, G.; Ammerer, H.P.; Brenner, H.; Slany, J. (Krankenanstalt der Stadt Wien Rudolfstiftung (Austria))

    1984-01-01

    Thrombosis of the basilar artery is not a rare disease, and the mortality is reported to be 60 to 80%. Present standard therapy with heparin infusions yields poor results. The high risk of intracerebral haemorrhage prohibits systemic fibrinolytic therapy. Due to these facts and good experience in our department with the use of local intracoronary lysis in acute myocardial infarction, the method of local thrombolysis was applied in a case of acute basiliar artery thrombosis. Fibrinolytic therapy was started via an angiography catheter placed in the vertebral artery in a 28 year-old woman with hemiplegia and severe brain stem symptoms. The patient received 200,000 IU streptokinase within 2 hours and subsequently 300,000 IU urokinase within 10 hours. The vessel re-opened completely. The neurological symptoms decreased during the following weeks. Based on this experience and according to rare reports in the literature we believe local low-dose thrombolysis to be a causal therapy promising success for acute thrombosis of the basilar artery. This therapy can be carried out in every medical centre able to perform selective angiography and experienced in the administration of fibrinolytic drugs.

  13. Atherosclerotic Aneurysm of the Basilar Artery and Hydrocephalus. A Case Report

    Directory of Open Access Journals (Sweden)

    Ania Alvarado Borges

    2014-08-01

    Full Text Available Intracranial aneurysms are fairly common. Many of them produce no symptoms, often remaining undiagnosed during life. At autopsy, aneurysms of the basilar artery appear in 2 to 5% of the cases; among them, saccular and congenital aneurysms are more common than atherosclerotic and fusiform aneurysms. A case of atherosclerotic aneurysm of the basilar artery diagnosed at autopsy in an 88-year-old man is presented. This patient had been admitted with a diagnosis of ischemic stroke, intracranial hypertension and hydrocephalus, which led physicians to consider a posterior fossa tumor. This paper aims at presenting the autopsy findings that showed the presence of an atherosclerotic aneurysm of the basilar artery.

  14. Endovascular treatment of basilar tip aneurysms associated with moyamoya disease

    Energy Technology Data Exchange (ETDEWEB)

    Arita, K.; Kurisu, K.; Ohba, S.; Shibukawa, M.; Kiura, H.; Sakamoto, S. [Department of Neurosurgery, Graduate School of Biomedical Science, Hiroshima University, 1-2-3 Kasumi, Minami-Ku, 734-8551, Hiroshima (Japan); Uozumi, T. [Hibino Hospital, Hiroshima (Japan); Nakahara, T. [Division of Neuroendovascular Treatment, Mazda Hospital, Hiroshima (Japan)

    2003-07-01

    We report the efficacy and safety of endovascular treatment of basilar tip aneurysms (BTA) in five patients with moyamoya disease. The patients underwent intra-aneurysmal embolisation with detachable platinum coils. Three BTA presented with subarachnoid haemorrhage (SAH); the other two were asymptomatic. In four cases, one embolisation procedure produced >95% angiographic obliteration of the aneurysm. In the other patient, 80-90% obliteration was achieved initially, but due to growth of the residual aneurysm, the procedure was repeated 7 months later. Two patients experienced transient oculomotor paresis as a procedure-related complication. Mean follow-up was 43.6{+-}34.0 months (range 8-92 months). One patient died of putaminal haemorrhage unrelated to the aneurysm 15 months after embolisation. The other four had no subsequent SAH and survived without sequelae. Endovascular embolisation using detachable platinum coils proved to be a safe and efficient treatment modality for BTA associated with moyamoya disease. (orig.)

  15. Post-Treatment Hemodynamics of a Basilar Aneurysm and Bifurcation

    Energy Technology Data Exchange (ETDEWEB)

    Ortega, J; Hartman, J; Rodriguez, J; Maitland, D

    2008-01-16

    Aneurysm re-growth and rupture can sometimes unexpectedly occur following treatment procedures that were initially considered to be successful at the time of treatment and post-operative angiography. In some cases, this can be attributed to surgical clip slippage or endovascular coil compaction. However, there are other cases in which the treatment devices function properly. In these instances, the subsequent complications are due to other factors, perhaps one of which is the post-treatment hemodynamic stress. To investigate whether or not a treatment procedure can subject the parent artery to harmful hemodynamic stresses, computational fluid dynamics simulations are performed on a patient-specific basilar aneurysm and bifurcation before and after a virtual endovascular treatment. The simulations demonstrate that the treatment procedure produces a substantial increase in the wall shear stress. Analysis of the post-treatment flow field indicates that the increase in wall shear stress is due to the impingement of the basilar artery flow upon the aneurysm filling material and to the close proximity of a vortex tube to the artery wall. Calculation of the time-averaged wall shear stress shows that there is a region of the artery exposed to a level of wall shear stress that can cause severe damage to endothelial cells. The results of this study demonstrate that it is possible for a treatment procedure, which successfully excludes the aneurysm from the vascular system and leaves no aneurysm neck remnant, to elevate the hemodynamic stresses to levels that are injurious to the immediately adjacent vessel wall.

  16. Basilar impression and osteogenesis imperfecta in a three-year-old girl: CT and MRI

    Energy Technology Data Exchange (ETDEWEB)

    Rush, P.J.; Berbrayer, D.; Reilly, B.J.

    1989-01-01

    A 3-year-old girl with osteogenesis imperfecta developed symptomatic basilar impression. Her neurological symptoms were treated by foramen magnum decompression and laminectomy. This is an unusually young patient to have this condition.

  17. The role of Na(+), K(+)-ATPase in the hypoxic vasoconstriction in isolated rat basilar artery.

    Science.gov (United States)

    Shen, Haitao; Liang, Peng; Qiu, Suhua; Zhang, Bo; Wang, Yongli; Lv, Ping

    2016-06-01

    Hypoxia-induced cerebrovascular dysfunction is a key factor in the occurrence and the development of cerebral ischemia. Na(+), K(+)-ATPase affects the regulation of intracellular Ca(2+) concentration and plays an important role in vascular smooth muscle function. However, the potential role of Na(+), K(+)-ATPase in hypoxia-induced cerebrovascular dysfunction is unknown. In this study, we found that the KCl-induced contraction under hypoxia in rat endothelium-intact basilar arteries is similar to that of denuded arteries, suggesting that hypoxia may cause smooth muscle cell (SMC)-dependent vasoconstriction in the basilar artery. The Na(+), K(+)-ATPase activity of the isolated basilar artery with or without endothelium significantly reduced with prolonged hypoxia. Blocking the Na(+)-Ca(2+) exchanger with Ni(2+) (10(-3)M) or the L-type Ca(2+) channel with nimodipine (10(-8)M) dramatically attenuated KCl-induced contraction under hypoxia. Furthermore, prolonged hypoxia significantly reduced Na(+), K(+)-ATPase activity and increased [Ca(2+)]i in cultured rat basilar artery SMCs. Hypoxia reduced the protein and mRNA expression of the α2 isoform of Na(+), K(+)-ATPase in SMCs in vitro. We used a low concentration of the Na(+), K(+)-ATPase inhibitor ouabain, which possesses a high affinity for the α2 isoform. The contractile response in the rat basilar artery under hypoxia was partly inhibited by ouabain pretreatment. The decreased Na(+), K(+)-ATPase activity in isolated basilar artery and the increased [Ca(2+)]i in SMCs induced by hypoxia were partly inhibited by pretreatment with a low concentration of ouabain. These results suggest that hypoxia may educe Na(+), K(+)-ATPase activity in SMCs through the α2 isoform contributing to vasoconstriction in the rat basilar artery.

  18. Basilar skull fracture in a Thoroughbred colt: Radiography or computed tomography?

    Directory of Open Access Journals (Sweden)

    Chee Kin Lim

    2013-04-01

    Full Text Available A two-year-old Thoroughbred colt was presented to the Equine Clinic, Onderstepoort Veterinary Academic Hospital for head trauma after rearing and falling backwards, hitting his head on the ground. Following medical therapy for acute onset neurological impairment secondary to a suspected basilar skull fracture, the horse was anaesthetised and computed tomography of the skull was performed. A diagnosis of a comminuted basilar skull fracture was made and skull radiographs were taken for comparison. The horse was subsequently euthanased owing to the poor prognosis; necropsy findings were compatible with imaging findings. The value and limitation of computed tomography versus radiography for the diagnosis of basilar skull fracture are discussed in this report. Introduction

  19. Basilar skull fracture in a Thoroughbred colt: Radiography or computed tomography?

    Directory of Open Access Journals (Sweden)

    Chee Kin Lim

    2013-02-01

    Full Text Available A two-year-old Thoroughbred colt was presented to the Equine Clinic, Onderstepoort Veterinary Academic Hospital for head trauma after rearing and falling backwards, hitting his head on the ground. Following medical therapy for acute onset neurological impairment secondary to a suspected basilar skull fracture, the horse was anaesthetised and computed tomography of the skull was performed. A diagnosis of a comminuted basilar skull fracture was made and skull radiographs were taken for comparison. The horse was subsequently euthanased owing to the poor prognosis; necropsy findings were compatible with imaging findings. The value and limitation of computed tomography versus radiography for the diagnosis of basilar skull fracture are discussed in this report.

  20. Rapid ventricular pacing for a basilar artery pseudoaneurysm in a pediatric patient: case report.

    Science.gov (United States)

    Nimjee, Shahid M; Smith, Tony P; Kanter, Ronald J; Ames, Warwick; Machovec, Kelly A; Grant, Gerald A; Zomorodi, Ali R

    2015-06-01

    Large cerebral aneurysms of the basilar apex are difficult to treat. Recently, endovascular treatment has mitigated much of the morbidity associated with treating these lesions. However, the morphology of aneurysms of the vertebrobasilar system can preclude endovascular treatment. Rapid ventricular pacing (RVP) facilitates open surgical treatment of cerebral aneurysms. It can assist in reducing the pressure of the neck of the aneurysm, allowing safe application of a clip. The authors present a case of a pediatric patient who developed a basilar artery pseudoaneurysm that required surgery. Given the large size of the aneurysm, RVP was performed, allowing the surgeons to dissect the dome of the aneurysm from the surrounding tissue and pontine perforating branches away from the lesion to safely clip the lesion. The patient had an uneventful recovery. To the authors' knowledge, this represents the first known case of RVP to aid in basilar artery clip occlusion in a pediatric patient.

  1. Characterization of CGRP(1) receptors in the guinea pig basilar artery

    DEFF Research Database (Denmark)

    Jansen-Olesen, I; Kaarill, L; Edvinsson, L

    2001-01-01

    The purpose of the present study was to characterise receptors mediating calcitonin gene-related peptide (CGRP)-induced relaxation of guinea pig basilar artery. This was done by investigating vasomotor responses in vitro and performing autoradiographic binding studies. We also intended to study...... the importance of an intact endothelium. Agonist studies showed that peptides of the CGRP family induced relaxation of the guinea pig basilar artery with the following order of potency: human beta-CGRP=human alpha-CGRP>adrenomedullin=[acetamidomethyl-Cys(2,7)]alpha-human CGRP ([Cys(ACM)(2,7)]CGRP...... in the absence of human CGRP-(8-37). The study shows the presence of a relaxant CGRP(1) receptor on the smooth muscle cells of guinea pig basilar artery. Various endothelial factors did not influence relaxant responses....

  2. 'Top of the basilar' syndrome: Clinico-radiological evaluation

    Energy Technology Data Exchange (ETDEWEB)

    Sato, M.; Tanaka, S.; Kohama, A.

    1987-07-01

    Sixteen patients having infarction caused by circulatory disturbance at the top of the basilar artery, that is to say, the 'top of the basilar' syndrome, were studied, the diagnosis having been made by computerized tomography. Infarcts were widely distributed in each patient between the thalamus, midbrain, pons, cerebellum, and occipital lobe. Both thalami were involved in 7 cases. When the thalamus was involved bilaterally, the low density areas were symmetrical in size and localization. Angiography revealed that stenosis or occlusion by within a circle 2 cm in diameter surrounding the five-forked junction at the top of the basilar artery in 84.6%. Recanalization of the occluded artery occurred in 61.5%, suggesting that embolism played an important role in appearance of this syndrome.

  3. [Thrombolysis of the basilar artery: 5-year results from the Saarland stroke registry].

    Science.gov (United States)

    Grunwald, I Q; Struffert, T; Roth, C; Papanagiotou, P; Scheuermann, J; Voges, M; Reith, W

    2005-05-01

    Acute thrombosis of the basilar artery has a fatal outcome if left untreated. The relatively good prognosis with intra-arterial thrombolysis makes it the therapy of choice for acute basilar thrombosis. In the Saarland stroke registry, we analyzed 47 patients with angiographically proven basilar artery thrombosis within the last 5 years. We observed a better outcome in patients with good income, with recanalization, and a short time between onset of symptoms and start of thrombolysis. The complications, such as intracerebral bleedings, occurred only in the group treated with rt-PA. Intra-arterial thrombolysis with urokinase or rt-PA is a relatively safe therapy, but should be performed in neuroradiological centers. With progressing symptoms the therapeutic window can be stretched up to 12 h, but coma lasting for more than 4 h is related to a bad outcome.

  4. Technical nuances of subtemporal approach for the treatment of basilar tip aneurysm

    Science.gov (United States)

    Nakov, Vladimir S.; Spiriev, Toma Y.; Todorov, Ivan T.; Simeonov, Plamen

    2017-01-01

    Background: Basilar tip aneurysms are one of the most complex vascular lesions to treat surgically because of their location, depth of the approach, and close proximity of vital neurovascular structures such as the mesencephalon, cranial nerves, perforating arteries to the thalamus. There are different surgical approaches utilized to reach basilar tip aneurysms, namely, pterional, pretemporal, orbitozygomatic, subtemporal, and anterior petrosectomy. Each of them has its advantages and limitations. Methods: In this paper, we present our personal experience with the use of subtemporal approach. The technique is described in detail including its nuances and potential pitfalls. Results: The subtemporal approach is indicated for basilar tip aneurysms located at the level of the floor of the sella turcica to 1 cm above the dorsum sellae. Conclusion: Subtemporal approach offers good surgical corridor for the management of these complex vascular lesions. PMID:28217394

  5. Pharmacological and molecular comparison of K(ATP) channels in rat basilar and middle cerebral arteries

    DEFF Research Database (Denmark)

    Ploug, Kenneth Beri; Edvinsson, Lars; Olesen, Jes;

    2006-01-01

    ATP-sensitive potassium (K(ATP)) channels play an important role in the regulation of cerebral vascular tone. In vitro studies using synthetic K(ATP) channel openers suggest that the pharmacological profiles differ between rat basilar arteries and rat middle cerebral arteries. To address this issue....... Densitometric measurements of the Western blot signals further showed higher expression levels of Kir6.1 and SUR2B proteins in rat middle cerebral arteries than was found in rat basilar arteries. In conclusion, our in vitro pharmacological studies showed no evidence for functional endothelial K(ATP) channels...

  6. Acute stenting and thromboaspiration in basilar artery occlusions due to embolism from the dominating vertebral artery

    Energy Technology Data Exchange (ETDEWEB)

    Nedeltchev, K.; Remonda, L.; Brekenfeld, C.; Ozdoba, C.; Schroth, G. [Institute of Diagnostic and Interventional Neuroradiology, University of Bern, Inselspital, Freiburgstrasse 4, 3010, Bern (Switzerland); Do, D.D. [Institute of Angiology, University of Bern, Inselspital, Bern (Switzerland); Arnold, M.; Mattle, H.P. [Department of Neurology, University of Bern, Inselspital, Bern (Switzerland)

    2004-08-01

    Intra-arterial thrombolysis (IAT) is the only treatment that has demonstrated benefit in patients with acute basilar artery occlusions (ABAO). IAT may be difficult to perform when access to the occluded basilar artery (BA) is prevented by pathology of the vertebral arteries (VA). We report on two patients with ABAO due to embolism from the dominating VA. Catheter navigation through the occluded VA and thromboaspiration enabled access to the BA. Thromboaspiration alone or in addition to IAT resulted in a complete recanalization of the BA and a favorable clinical outcome. A stent was deployed at the site of the stenosis in the VA either prior to or immediately after BA recanalization. (orig.)

  7. Osteogenesis imperfecta in childhood: MR imaging of basilar impression

    Energy Technology Data Exchange (ETDEWEB)

    Janus, G.J.M. E-mail: janus@knmg.nl; Engelbert, R.H.H.; Beek, E.; Gooskens, R.H.J.M.; Pruijs, J.E.H

    2003-07-01

    Objective: To determine on radiographs the presence of Basilar Impression (BI) in children with Osteogenesis Imperfecta (OI). To confirm this sign and altered geometrical relationships of the craniocervical junction in course of time with magnetic resonance imaging (MRI). Methods and patients: In a cohort study of 130 patients with OI (OI type I: 85; OI type III: 21; OI type IV: 24) lateral radiographs of the skull and cervical spine were made in a standardised way. MRI scans were performed when BI was suspected based upon protrusion of the odontoid above Chamberlain's line. Intracranial abnormalities as well as the basal angle were described. Neurological examination was performed in patients with conclusive BI at MRI-scan. Results and discussion: In eight patients BI could be confirmed by MRI-scan. None of the children had or developed in time neurological symptoms or signs. Follow up of BI by MRI scans was done in seven patients (mean: 5 years; range: 2-6 years). No alteration of intracranial findings were seen at subsequent investigation, although in one child Chamberlain's line increased from 8 (first MRI) to 15 mm (last MRI). BI can be diagnosed by radiographs but in the extreme osteoporotic bone and altered anatomy of the craniocervical junction of children with OI MRI is preferable. As intracranial pathology can be demonstrated by MRI, also a relation can be laid to possible neurological symptoms and signs at clinical examination. Conclusion: In our cohort study no alteration of the intracranial contents was seen at subsequent MRI scans. Although anatomic deformations exist in BI, no neurological symptoms or signs were present in our study and no operative reconstruction had to be performed. Periodical MRI-scan has not been of influence on the clinical decision making process. At the moment we perform a MRI-scan if BI is suspected at lateral skull radiographs. The MRI images serve as reference findings to anticipate on possible future symptoms and

  8. Unusual origin of the left ophthalmic artery from the basilar trunk.

    Science.gov (United States)

    Rivera, Rodrigo; Choi, In Sup; Sordo, Juan Gabriel; Giacaman, Pablo; Badilla, Lautaro; Bravo, Eduardo; Echeverria, Daniel

    2015-05-01

    The formation of the ophthalmic artery (OA) is a complex process with two different proposed embryological steps for its development. Several anatomical variants have been described. We present a very unusual origin of the ophthalmic artery from the basilar trunk, in a 45-year-old male with a history of pontine hemorrhagic stroke. MRI and CTA showed evidence of previous hemorrhage in the pons and several intracranial arterial dysplastic dilatations. DSA confirmed several fusiform dilatations of the basilar trunk. In the left ICA, no ophthalmic artery was seen arising from the carotid siphon. The left ophthalmic artery arises from the basilar trunk and runs lateral to the cavernous sinus through the middle cranial fossa, entering the left orbit at the superior orbital fissure. The patient was treated conservatively. Two main theories for this anomaly are known, one from Lasjaunias and the other from Paget. To our knowledge, this basilar origin of the OA has only been described three times in the literature. For its origin, we propose a partial persistence of the trigeminal artery together with a dominance of the dorsal ophthalmic artery.

  9. Pharmacological and molecular comparison of K(ATP) channels in rat basilar and middle cerebral arteries

    DEFF Research Database (Denmark)

    Ploug, Kenneth Beri; Edvinsson, Lars; Olesen, Jes;

    2006-01-01

    ATP-sensitive potassium (K(ATP)) channels play an important role in the regulation of cerebral vascular tone. In vitro studies using synthetic K(ATP) channel openers suggest that the pharmacological profiles differ between rat basilar arteries and rat middle cerebral arteries. To address this issue...

  10. Basilar impression associated with impacted cisterna magna, spastic paraparesis and distress of balance: case report

    Directory of Open Access Journals (Sweden)

    Gonçalves da Silva José Alberto

    2006-01-01

    Full Text Available We report on a 48 years-old man with basilar impression without syringohydromyelia, in which the cisterna magna was impacted by the cerebellar tonsils. Six months after posterior fossa decompression there was the disappearance of nuchal rigidity, vertigo, spastic paraparesis and improvement of balance. Nevertheless hyperreflexia and diminished pallesthesia of the lower limbs persisted.

  11. Cross-sectional imaging for diagnosis and clinical outcome prediction of acute basilar artery thrombosis

    Energy Technology Data Exchange (ETDEWEB)

    Mortimer, A.M., E-mail: alex_mortimer@hotmail.co [Severn School of Radiology, Bristol (United Kingdom); Department of Radiology, Great Western Hospital, Swindon (United Kingdom); Saunders, T.; Cook, J.-L. [Department of Radiology, Great Western Hospital, Swindon (United Kingdom)

    2011-06-15

    Basilar artery occlusion is a potentially fatal condition and imaging findings can be subtle. Prompt diagnosis is vital, as recognition may lead to therapeutic recanalization that may improve functional outcome and survival. Furthermore, cross-sectional imaging signs may help predict eventual outcome and, therefore, guide which patients should be subjected to aggressive treatment. Computed tomography (CT) signs include a hyperdense basilar artery that has a high specificity, accuracy, positive and negative predictive value. Evidence regarding the prognostic significance of the hyperdense basilar artery sign is conflicting. Early magnetic resonance imaging (MRI) features include loss of flow void, seen as increased signal intensity within the basilar artery on T2-weigted images and identification of acute thrombus, seen as intermediate signal on T1-weighted images. MRI sequences are more sensitive for early detection of acute ischaemia or infarction, ideally with diffusion-weighted imaging (DWI). Both CT and MR angiography are sensitive for detection of acute thrombus, seen as a filling defect or occlusion. These are the non-invasive imaging techniques of choice to confirm diagnosis, with perhaps the speed and accessibility of CT angiography resulting in this technique being valuable in the acute setting. Several new scoring systems based on arterial segmentation rather than global volume assessment using CT angiography source images and DWI have shown early promise in the prediction of eventual clinical outcome in order to isolate those patients who may benefit from therapeutic recanalization.

  12. Prodromal Transient Ischemic Attack or Minor Stroke and Outcome in Basilar Artery Occlusion

    NARCIS (Netherlands)

    Conforto, Adriana B.; De Freitas, Gabriel R.; Schonewille, Wouter J.; Kappelle, L. Jaap; Algra, Ale

    2015-01-01

    Background The presence of prodromal transient ischemic attacks (TIAs) has been associated with a favorable outcome in anterior circulation stroke. We aimed to determine the association between prodromal TIAs or minor stroke and outcomes at 1 month, in the Basilar Artery International Cooperation St

  13. Prodromal Transient Ischemic Attack or Minor Stroke and Outcome in Basilar Artery Occlusion

    NARCIS (Netherlands)

    Conforto, A.B.; Freitas, G.R. de; Schonewille, W.J.; Kappelle, L.J.; Algra, A.; Leeuw, F.E. de

    2015-01-01

    BACKGROUND: The presence of prodromal transient ischemic attacks (TIAs) has been associated with a favorable outcome in anterior circulation stroke. We aimed to determine the association between prodromal TIAs or minor stroke and outcomes at 1 month, in the Basilar Artery International Cooperation S

  14. Different Imaging Strategies in Patients with Possible Basilar Artery Occlusion: Cost-Effectiveness Analysis

    NARCIS (Netherlands)

    S.E. Beyer (Sebastian E.); M.G.M. Hunink (Myriam); F. Schöberl (Florian); L. von Baumgarten; S.E. Petersen (Steffen); C. Kubisch (Christian); H. Janssen (Hendrik); B. Ertl-Wagner (Birgit); M.F. Reiser (Maximilian F.); W.H. Sommer (Wieland H.)

    2015-01-01

    textabstractBackground and Purpose-This study evaluated the cost-effectiveness of different noninvasive imaging strategies in patients with possible basilar artery occlusion. Methods-A Markov decision analytic model was used to evaluate long-term outcomes resulting from strategies using computed tom

  15. Obstrução do tronco basilar: registro de três casos

    Directory of Open Access Journals (Sweden)

    Adolfo Pou-Serradel

    1984-06-01

    Full Text Available Registro de três casos de obliteração do tronco basilar, todos êles em uma idade em que a arteriosclerose é infrequente. O diagnóstico foi confirmado angiograficamente. A evolução foi diferente em cada um deles.

  16. EFFECT OF ACUPUNCTURE ON BLOOD FLOW OF VERTEBRAL AND BASILAR ARTERIES IN STROKE PATIENTS

    Institute of Scientific and Technical Information of China (English)

    吕建明; 王伟志

    2004-01-01

    Objective: To observe the short-term effect and long-term effect of acupuncture on blood flow of vertebral and basilar arteries in stroke patients.Methods: A total of 58 stroke patients (34 males and 24 females) were agreed to participate in this study, and changes of blood flow of the vertebral and basilar arteries were detected after one week's and 45 days' continuous acupuncture treatment by using a Doppler's ultrasonic diagnosis apparatus.Bilateral Fengchi (GB 20), Wangu (GB 12), Tianzhu (BL 10), etc.were punctured and stimulated with small amplitude, high frequency and twirling-reinforcing method for 3 min.The treatment was conducted once daily.Results: Following one week's and 45 days' acupuncture treatment, diastolic velocity (DV), systolic velocity (SV) and mean velocity (MV) of the basilar artery increased significantly in comparison with pre-treatment (P0.05).Results indicated that acupuncture treatment could effectively improve blood supply of the basilar artery and regulate the uneven blood flow of the bilateral vertebral arteries.Conclusion: Acupuncture treatment can raise blood flow of the brain in stroke patients.

  17. Effects of K+ channel agonists cromakalim and pinacidil on rat basilar artery smooth muscle cells are mediated by Ca(++)-activated K+ channels.

    Science.gov (United States)

    Stockbridge, N; Zhang, H; Weir, B

    1991-11-27

    Whole-cell and cell-free inside-out patch-clamp recording techniques were used to examine the actions of potassium channel openers pinacidil and cromakalim in enzymatically isolated smooth muscle cells of rat basilar artery. Delayed rectifier and calcium-dependent potassium currents were identified from the whole-cell recordings. Only the calcium-dependent potassium current was increased by cromakalim and pinacidil. Recordings from inside-out membrane patches revealed a large conductance voltage- and calcium-dependent potassium channel, which was blocked by charybdotoxin but unaffected by ATP less than 10 mM. Cromakalim and pinacidil increased the open probability of this channel. On the basis of these results, we suggest that such drugs, acting on cerebral arterial smooth muscle cell potassium channels, may be of some benefit in the treatment of cerebral vasospasm following subarachnoid hemorrhage.

  18. Hemiplegia cruzada associada a impressão basilar, malformação de Arnold-Chiari e siringomielia: relato de caso Cruciate hemiplegia associated with basilar impression, Arnold-Chiari malformation and syringomyelia: case report

    Directory of Open Access Journals (Sweden)

    José Alberto Gonçalves da Silva

    1996-12-01

    Full Text Available Os autores apresentam um caso de hemiplegia cruzada associada a impressão basilar, malformação de Arnold-Chiari e siringomielia. Discutem as propostas anatômicas e a fiopatogenia desta síndrome de ocorrência bastante rara.The authors report a case of cruciate hemiplegia associated with basilar impression, Chiari malformation and syringomyelia. The neuroanatomical controversy, the surgical treatment and the good outcome of the patient are discussed.

  19. The Challenge of Managing Fusiform Basilar Artery Aneurysms: From Acute Ischemic Stroke to a Massive Subarachnoid Hemorrhage

    Directory of Open Access Journals (Sweden)

    Sofia Bezerra

    2011-02-01

    Full Text Available We present the case of a patient with acute brain stem ischemic stroke who was found to have a fusiform basilar aneurysm with a thrombus within the dilated vessel. Three days after the ischemic stroke, the patient had a massive subarachnoid hemorrhage and died. This case illustrates the difficulties in the acute management of ischemic events in patients with basilar fusiform aneurysms, because the natural history of this disease encompasses both bleeding and thrombosis.

  20. The efficiency analysis of thrombolytic rt-PA combined with intravascular interventional therapy in patients with acute basilar artery occlusion

    Science.gov (United States)

    Xianxian, Zhao; Chengsong, Yue; Qiang, Mei; Fei, Wei; Lin, Shen; Huiyan, Ding; Zili, Gong

    2017-01-01

    In order to further optimize the treatment strategy for the patients with acute basilar artery occlusion, we were dedicated to study the therapeutic effects and influential factors in the process of treated basilar artery occlusion with thrombolytic combined vascular interventional therapy. 75 patients with acute basilar artery occlusion treated with arterial thrombolytic therapy were analyzed retrospectively. In accordance with the discharge records of patients, their short-term curative effect with 24-hour treatment and 14-days treatment were evaluated. Our data showed that the survival condition of the patients with acute acute basilar artery occlusion were visibly improved by combination thrombolytic and interventional therapy. Moreover, their BI scores were remarkably improved, while NIHSS and mRS scores were evidently reduced. These data proved that our treatment strategy was able to improve the survival condition of patients with acute basilar artery occlusion. Furthermore, our data showed that coagulation related factors remarkably improved in the patients, when they treated by combination thrombolytic therapy with interventional therapy. In addition, our results suggested that the patients' bilateral Babinski(+), revascularization and coma symptom were closely related to their prognosis after treated the patients with combination thrombolytic and vascular interventional therapy, and the difference was statistically significant (pBabinski(+), and revascularization in the patients with acute basilar artery occlusion have an appreciable impact on the patients' prognosis. PMID:28123346

  1. Comparison of P2X receptors in rat mesenteric, basilar and septal (coronary) arteries.

    Science.gov (United States)

    Lewis, C J; Evans, R J

    2000-07-01

    alpha beta meATP-evoked concentration-dependent, PPADS-sensitive, desensitising, P2X receptor-mediated, constrictions of mesenteric, basilar and septal artery rings with EC(50) values of 1, 1 and 30 microM, respectively. In patch clamp studies on acutely dissociated artery smooth cells alpha beta meATP-evoked transient inward currents (tau approximately 100 ms) with mean current densities of approximately 340, 175 and 120 pA/pF, respectively. P2X(1) receptor immunoreactivity was expressed in mesenteric and basilar arteries and this receptor subunit appears to dominate the P2X receptor phenotype in these vessels. In contrast P2X(1) receptor immunoreactivity was not detected in septal arteries and the alpha beta meATP sensitivity of constriction was not consistent with the involvement of P2X(1) receptors. These results suggest that not all arteries share a common P2X receptor phenotype.

  2. Contractile responses to rat urotensin II in resting and depolarized basilar arteries.

    Science.gov (United States)

    Porras-González, Cristina; Ureña, Juan; Egea-Guerrero, Juan José; Gordillo-Escobar, Elena; Murillo-Cabezas, Francisco; González-Montelongo, María del Carmen; Muñoz-Sánchez, María Angeles

    2014-03-01

    The effects of human urotensin II (hUII) on the vascular tone of different animal species has been studied extensively. However, little has been reported on the vasoactive effects of rat urotensin (rUII) in murine models. The aim of the present study was to investigate the effects of rUII on vasoreactivity in rat basilar arteries. Basilar arteries from adult male Wistar rats (300-350 g) were isolated, cut in rings, and mounted on a small vessel myograph to measure isometric tension. rUII concentrations were studied in both resting and depolarized state. To remove endothelial nitric oxide effects from the rUII response, we treated selected arterial rings with Nω-nitro-L-arginine methyl ester (L-NAME). 10 μM rUII produced a potent vasoconstrictor response in rat basilar arteries with intact endothelium, while isometric forces remained unaffected in arterial rings treated with lower rUII concentrations. Although L-NAME did not have a significant effect on 10 μM rUII-evoked contraction, it slightly increased arterial ring contraction elicited by 1 μM rUII. In depolarized arteries, dose-dependent rUII increased depolarization-induced contractions. This effect was suppressed by L-NAME. Our results show that the rat basilar artery has a vasoconstrictor response to rUII. The most potent vasoconstrictor effect was produced by lower doses of rUII (0.1 and 1 μM) in depolarized arteries with intact endothelium. This effect could facilitate arterial vasospasm in vascular pathophysiological processes such as subarachnoid hemorrhage and hypertension, when sustained depolarization and L-type Ca(2+) channel activation are present.

  3. Basilar invagination secondary to hypoplasia of the clivus - Is there indication for craniocervical fixation?

    OpenAIRE

    2014-01-01

    The posterior fossa decompression is a form of treatment suggested for patients with basilar invagination (BI) secondary to hypoplasia symptomatic of the clivus and atlantoaxial alignment preserved. Based on the fact that the worsening of cranial-cervical kyphosis (decrease of clivus-canal angle to less than 150o) can result in anterior brainstem compression, we propose that some patients may benefit from the cranio-cervical fixation. We present a case report of a patient with BI secondary to...

  4. RESULTS OF THE USE OF PEEK CAGES IN THE TREATMENT OF BASILAR INVAGINATION BY GOEL TECHNIQUE

    Directory of Open Access Journals (Sweden)

    Luís Eduardo Carelli Teixeira da Silva

    2016-03-01

    Full Text Available ABSTRACT Objective: Analysis of the use of polyetheretherketone (PEEK cages for atlantoaxial facet realignment and distraction for treatment of basilar invagination by Goel technique. Method: Retrospective descriptive statistical analysis of the neurological status, pain, presence of subsidence and bone fusion with the use of PEEK cages in 8 atlantoaxial joints of 4 patients with basilar invagination. All patients were treated with atlantoaxial facet distraction and realignment and subsequent arthrodesis C1-C2 by the technique of Goel modified by the use of PEEK cage. Results: All patients showed improvement in Nurick neurological assessment scale and Visual Analogue Scale (VAS of pain. There were no cases of subsidence, migration, or damage to the vertebral artery during the insertion of the cage. All joints evolved with bone fusion, assessed by dynamic radiographs, and computed tomography. Two patients developed neuropathic pain in dermatome of C2 and one patient had unilateral vertebral artery injury during C2 instrumentation treated with insertion of pedicle screw to control the bleeding. Conclusion: The results of the treatment of basilar invagination by the Goel technique with the use of PEEK cages shown to be effective and safe although further studies are needed to confirm this use.

  5. A Vertebral Artery Dissection with Basilar Artery Occlusion in a Child

    Directory of Open Access Journals (Sweden)

    Katleen Devue

    2014-01-01

    Full Text Available This paper presents the case report of an 11-year-old boy with an acute dissection with thrombosis of the left vertebral artery and thrombosis of the basilar artery. The patient was treated with acute systemic thrombolysis, followed by intra-arterial thrombolysis, without any clinical improvement, showing left hemiplegia, bilateral clonus, hyperreflexia, and impaired consciousness. MRI indicated persistent thrombosis of the arteria basilaris with edema and ischemia of the right brainstem. Heparinization for 72 hours, followed by a two-week LMWH treatment and subsequent oral warfarin therapy, resulted in a lasting improvement of the symptoms. Vertebral artery dissection after minor trauma is rare in children. While acute basilar artery occlusion as a complication is even more infrequent, it is potentially fatal, which means that prompt diagnosis and treatment are imperative. The lack of class I recommendation guidelines for children regarding treatment of vertebral artery dissection and basilar artery occlusion means that initial and follow-up management both require a multidisciplinary approach to coordinate emergency, critical care, interventional radiology, and child neurology services.

  6. Megadolicho basilar artery as a cause of asymmetrical sensorineural hearing loss - case report

    Directory of Open Access Journals (Sweden)

    Melo, Antonio Antunes

    2011-07-01

    Full Text Available Introduction: At the differentiated diagnosis of asymmetrical sensorineural hearing losses, vascular disorders are present, one of which is megadolicho basilar artery. This disease is generally asymptomatic, and when symptoms are found, they can be caused by a compression or ischemia. Clinically, sensorineural hearing loss, tinnitus, headache, facial hypoesthesia, trigeminal neuralgia, vertigo, diplopia and facial palsy, among others, are likely to occur. The image examination of choice for its diagnosis is nuclear magnetic resonance. The megadolicho basilar artery therapy can be surgical or conservative, according to the associated findings. A multidisciplinary approach, including a neurologist, neurosurgeon and an otorhinolaryngologist is recommended for a proper administration of the case. Objective: Report the case of a patient with asymmetrical sensorineural hearing loss, diagnosed of megadolicho basilar artery. Case report: JBS, 57-year-old white male with a history of asymmetrical sensorineural hearing loss and bilateral whistle-like tinnitus for several years. The otorhinolaryngologic evaluation, including otoscopy, anterior rhinoscopy and oral pharynx, was normal. Final Comments: The treatment consisted in following up with the patient, controlling the tinnitus by drugs and using an individual sound amplification apparatus on the left ear.

  7. The challenge of basilar artery occlusion wake-up stroke: too late for intravenous thrombolysis?

    Science.gov (United States)

    Caliandro, Pietro; Reale, Giuseppe; Tartaglione, Tommaso; Rossini, Paolo Maria

    2016-07-01

    We describe the case of a patient carried to our emergency department, with the wake-up finding of dysarthria, right hemiplegia and worsening consciousness impairment (NIHSS 12). After performing a CT angiography, which showed complete basilar occlusion, we determined the MR DWI-FLAIR mismatch to estimate the stroke onset time. Because of the favorable mismatch (DWI hyperintensity in the left pons, no FLAIR hyperintensity in the same region), the patient underwent thrombolysis with sudden neurological improvement. In addition, the DWI hyperintensity first observed in the left pons totally regressed after thrombolysis. Wake-up stroke constitutes about 14 % of all strokes, while the percentage of basilar artery occlusion wake-up strokes is still unknown. Although thrombolysis in patients with unknown-onset time is still an off-label therapy, basilar artery occlusion is a potentially fatal event. In our case we used RM DWI-FLAIR mismatch to rapidly estimate the stroke onset time and to treat the patient with an off-label but potentially effective and safe therapy.

  8. Transient basilar artery occlusion monitored by transcranial color Doppler presenting with a spectacular shrinking deficit: a case report

    Directory of Open Access Journals (Sweden)

    Del Sette Massimo

    2010-01-01

    Full Text Available Abstract Introduction We describe the case of a 79-year-old Caucasian Italian woman with a transient basilar occlusion monitored by transcranial Doppler, with subsequent recanalization and clinical shrinking deficit. This is the first case of transient basilar occlusive disease diagnosed and monitored by transcranial Doppler. This case is important and needs to be reported because transient basilar occlusion may be easily diagnosed if transcranial Doppler is performed. Case presentation A 79-year-old woman affected by chronic atrial fibrillation and not treated with oral anticoagulants, cardioverted to sinus rhythm during a gastric endoscopy. She then showed a sudden-onset loss of consciousness, horizontal and vertical gaze palsy, tetraparesis and bilateral miosis and coma. Two hours later, the symptoms resolved quickly, leaving no residual neurologic deficits. Transcranial Doppler examination showed a dampened flow in the basilar artery in the emergency examination and a restored flow when the symptoms resolved. Conclusion This is the first case of transient basilar occlusive disease diagnosed and monitored by transcranial Doppler. We believe that transcranial Doppler should be performed in all cases of unexplained acute loss of consciousness, in particular, if associated with signs of brainstem dysfunctions.

  9. Sensitivity of Hyperdense Basilar Artery Sign on Non-Enhanced Computed Tomography.

    Directory of Open Access Journals (Sweden)

    Marielle Ernst

    Full Text Available The hyperdense basilar artery sign (HBAS is an indicator of vessel occlusion on non contrast-enhanced computer tomography (NECT in acute stroke patients. Since basilar artery occlusion (BAO is associated with a high mortality and morbidity, its early detection is of great clinical value. We sought to analyze the influence of density measurement as well as a normalized ratio of Hounsfield unit/hematocrit (HU/Hct ratio on the detection of BAO on NECT in patients with suspected BAO.102 patients with clinically suspected BAO were examined with NECT followed immediately by Multidetector computed tomography Angiography. Two observers independently analyzed the images regarding the presence or absence of HBAS on NECT and performed HU measurements in the basilar artery. Receiver operating characteristic curve analysis was performed to determine the optimal density threshold for BAO using attenuation measurements or HU/Hct ratio.Sensitivity of visual detection of the HBAS on NECT was relatively low 81% (95%-CI, 54-95% while specificity was high 91% (95%-CI, 82-96%. The highest sensitivity was achieved by the combination of visual assessment and additional quantitative attenuation measurements applying a cut-off value of 46.5 HU with 94% sensitivity and 81% specificity for BAO. A HU/Hct ratio >1.32 revealed sensitivity of 88% (95%-CI, 60-98% and specificity of 84% (95%-CI, 74-90%.In patients with clinically suspected acute BAO the combination of visual assessment and additional attenuation measurement with a cut-off value of 46.5 HU is a reliable approach with high sensitivity in the detection of BAO on NECT.

  10. Successful treatment of a giant pediatric fusiform basilar trunk aneurysm with surpass flow diverter.

    Science.gov (United States)

    Kan, Peter; Mokin, Maxim; Puri, Ajit S; Wakhloo, Ajay K

    2016-06-01

    Fusiform aneurysms present a unique challenge to traditional microsurgical and endovascular treatment because of the lack of a discernible neck and the involvement of parent vessel. Flow diversion has increasingly become the treatment of choice for fusiform aneurysms in the anterior circulation, but its results in the posterior circulation are variable. We report successful treatment of a giant fusiform upper basilar trunk aneurysm with the Surpass flow diverter in an adolescent, and discuss the potential advantages of this emerging technology in the treatment of fusiform posterior circulation aneurysms.

  11. Basilar invagination secondary to hypoplasia of the clivus - Is there indication for craniocervical fixation?

    Directory of Open Access Journals (Sweden)

    Andrei Fernandes Joaquim

    2014-03-01

    Full Text Available The posterior fossa decompression is a form of treatment suggested for patients with basilar invagination (BI secondary to hypoplasia symptomatic of the clivus and atlantoaxial alignment preserved. Based on the fact that the worsening of cranial-cervical kyphosis (decrease of clivus-canal angle to less than 150o can result in anterior brainstem compression, we propose that some patients may benefit from the cranio-cervical fixation. We present a case report of a patient with BI secondary to clivus hypoplasia who underwent cranio-cervical fixation in extension, with a reduction in clivus-canal angle and improvement of symptoms without posterior fossa decompression.

  12. Successful treatment of a giant pediatric fusiform basilar trunk aneurysm with surpass flow diverter.

    Science.gov (United States)

    Kan, Peter; Mokin, Maxim; Puri, Ajit S; Wakhloo, Ajay K

    2015-06-03

    Fusiform aneurysms present a unique challenge to traditional microsurgical and endovascular treatment because of the lack of a discernible neck and the involvement of parent vessel. Flow diversion has increasingly become the treatment of choice for fusiform aneurysms in the anterior circulation, but its results in the posterior circulation are variable. We report successful treatment of a giant fusiform upper basilar trunk aneurysm with the Surpass flow diverter in an adolescent, and discuss the potential advantages of this emerging technology in the treatment of fusiform posterior circulation aneurysms.

  13. Endothelin-1 and endothelin receptors in the basilar artery of the capybara.

    Science.gov (United States)

    Loesch, Andrzej; Gajkowska, Barbara; Dashwood, Michael R; Fioretto, Emerson T; Gagliardo, Karina M; Lima, Ana R De; Ribeiro, Antonio A C M

    2005-02-01

    Little is known about cerebral vasculature of capybara, which seems may serve as a natural model of studying changes in cerebral circulation due to internal carotid artery atrophy at animal sexual maturation. This is the first study of the light- and electron-immunocytochemical localisation of endothelin-1 (ET-1) and ETA and ETB endothelin receptors in the basilar artery of capybaras (6 to 12-month-old females and males) using an ExtrAvidin detection method. All animals examined showed similar patterns of immunoreactivity. Immunoreactivity for ET-1 was detected in the endothelium and adventitial fibroblasts, whilst immunoreactivity for ETA and ETB receptors was present in the endothelium, vascular smooth muscle, perivascular nerves and fibroblasts. In endothelial cells immunoreactivity to ET-1 was pronounced in the cytoplasm or on the granular endoplasmic reticulum. Similar patterns of immunolabelling were observed for ETA and ETB receptors, though cytoplasmic location of clusters of immunoprecipitate seems dominant. These results suggest that the endothelin system is present throughout the wall of the basilar artery of capybara.

  14. High cervical C3-4 ′disc′ compression associated with basilar invagination

    Directory of Open Access Journals (Sweden)

    Goel Atul

    2008-01-01

    Full Text Available A 20-year-old male had torticollis and short neck since birth. He presented with symptom of progressive quadriparesis over a two-year period. Investigations revealed basilar invagination with marked rotation in the craniovertebral region and relatively large C3-4 region osteophytes. Serial MRI over two years showed persistent signal opposite C3-4 disc space suggestive of cord compression. Although the cord was humped over the odontoid process, there was no clear radiological evidence that the cord was compromised at this level. During surgery, instability was identified only at the craniovertebral region and not at the level of C3-4. Distraction of the lateral masses of atlas and axis and fixation using interarticular spacers and bone graft and direct screw implantation in the lateral mass of the atlas and pars of the axis resulted in reduction of the basilar invagination and of atlantoaxial dislocation. The patient had marked clinical recovery, despite the fact that no direct procedure was done for C3-4 disc decompression. The case suggests that C3-4 disc changes could be secondary to primary instability at the craniovertebral junction.

  15. 'Top of the basilar' syndrome. Clinico-radiological evaluation

    Energy Technology Data Exchange (ETDEWEB)

    Sato, Masaharu; Kuroda, Ryotaro; Nakatani, Jiro; Watanabe, Masaru; Akai, Fumiharu; Ioku, Masahiko

    1988-06-01

    Seventeen patients (age 23 - 81) having the ''top of the basilar'' syndrome were the subjects of this study. They were evaluated clinico-radiologically. The diagnosis of this syndrome was made by computerized tomography. The infarcted lesions of each patient were widely distributed in many areas among the thalamus, midbrain, pons, cerebellum, and occipital lobe. Both the thalami were involved in 8 patients. When the thalamus was involved bilaterally, the low density areas of both the thalami were demonstrated to be almost the same in size and symmetric in localization by computerized tomography, showing a characteristic pattern. Further, magnetic resonance imaging could reveal small lesions in the brain stem minutely. Angiography revealed that stenosis or occlusion was within the circle of 2 cm in diameter surrounding the five-forked road of the top of the basilar artery in 84.6 %. Recanalization of the occluded artery occurred in 61.5 %, which suggests that the embolism plays an important role in appearance of this syndrome. In spite of frequent recanalization hemorrhagic infarction never occurred. The prognosis was very poor.

  16. Computational fluid dynamics evaluation of flow reversal treatment of giant basilar tip aneurysm.

    Science.gov (United States)

    Alnæs, Martin Sandve; Mardal, Kent-Andre; Bakke, Søren; Sorteberg, Angelika

    2015-10-01

    Therapeutic parent artery flow reversal is a treatment option for giant, partially thrombosed basilar tip aneurysms. The effectiveness of this treatment has been variable and not yet studied by applying computational fluid dynamics. Computed tomography images and blood flow velocities acquired with transcranial Doppler ultrasonography were obtained prior to and after bilateral endovascular vertebral artery occlusion for a giant basilar tip aneurysm. Patient-specific geometries and velocity waveforms were used in computational fluid dynamics simulations in order to determine the velocity and wall shear stress changes induced by treatment. Therapeutic parent artery flow reversal lead to a dramatic increase in aneurysm inflow and wall shear stress (30 to 170 Pa) resulting in an increase in intra-aneurysmal circulation. The enlargement of the circulated area within the aneurysm led to a re-normalization of the wall shear stress and the aneurysm remained stable for more than 8 years thereafter. Therapeutic parent artery flow reversal can lead to unintended, potentially harmful changes in aneurysm inflow which can be quantified and possibly predicted by applying computational fluid dynamics.

  17. Successful coil embolization of a ruptured basilar artery aneurysm in a child with leukemia: a case report.

    Science.gov (United States)

    Hayashi, Shihori; Maehara, Taketoshi; Mukawa, Maki; Aoyagi, Masaru; Yoshino, Yoshikazu; Nemoto, Shigeru; Ono, Toshiaki; Ohno, Kikuo

    2014-01-01

    Ruptured intracranial aneurysms are rare in the pediatric population compared to adults. This has incited considerable discussion on how to treat children with this condition. Here, we report a child with a ruptured saccular basilar artery aneurysm that was successfully treated with coil embolization. A 12-year-old boy with acute lymphoblastic leukemia and accompanying abdominal candidiasis after chemotherapy suddenly complained of a severe headache and suffered consciousness disturbance moments later. Computed tomography scans and cerebral angiography demonstrated acute hydrocephalus and subarachnoid hemorrhage caused by saccular basilar artery aneurysm rupture. External ventricular drainage was performed immediately. Because the patient was in severe condition and did not show remarkable signs of central nervous system infection in cerebrospinal fluid studies, we applied endovascular treatment for the ruptured saccular basilar artery aneurysm, which was successfully occluded with coils. The patient recovered without new neurological deficits after ventriculoperitoneal shunting. Recent reports indicate that both endovascular and microsurgical techniques can be used to effectively treat ruptured cerebral aneurysms in pediatric patients. A minimally invasive endovascular treatment was effective in the present case, but long-term follow-up will be necessary to confirm the efficiency of endovascular treatment for children with ruptured saccular basilar artery aneurysms.

  18. Elongation and dilatation of the basilar artery in CT imaging; Wydluzenie i poszerzenie tetnicy podstawowej w obrazie KT

    Energy Technology Data Exchange (ETDEWEB)

    Lasek, W.; Burzynska-Makuch, M.; Pilecki, S.; Grzegorzewski, M.; Boron, Z. [Akademia Medyczna, Bydgoszcz (Poland)

    1994-12-31

    During two years 5 rare cases of elongation and dilatation of basilar artery were recognized in CT examination. In patients with cranial nerve deficits, cerebellar, brainstem and ponto-cerebellar angle signs artery megadolichobasilaris should be taken into account. CT examination is the sufficient method to see the diagnosis. (author). 15 refs, 3 tabs, 4 figs.

  19. Transfundal stent placement for treatment of complex basilar tip aneurysm: technical note

    Science.gov (United States)

    Vasquez, Ciro; Hubbard, Molly; Jagadeesan, Bharathi Dasan; Tummala, Ramachandra Prasad

    2014-01-01

    We describe a case where a complex unruptured basilar tip aneurysm was treated with a unique method of stent-assisted coil embolization. The aneurysm was considered to have a complex anatomy since both the left posterior cerebral artery and left superior cerebellar artery originated from the dome of the aneurysm. Also, the right posterior cerebral artery was incorporated in the aneurysm neck and needed to be protected prior to coil embolization. This case describes placement of a stent across the span of the aneurysm fundus in order to preserve the two branches arising from it, and the aneurysm dome was coiled without any complication. Using modifications of existing strategies for stent-assisted coil embolization, the aneurysm was treated without any complications and all of the vessels at risk were preserved. PMID:25336546

  20. Incidence of basilar invagination in patients with tonsillar herniation ? a case control craniometrical study

    Directory of Open Access Journals (Sweden)

    Andrei F Joaquim

    2014-09-01

    Full Text Available A retrospective case-control study based on craniometrical evaluation was performed to evaluate the incidence of basilar invagination (BI. Patients with symptomatic tonsillar herniation treated surgically had craniometrical parameters evaluated based on CT scan reconstructions before surgery. BI was diagnosed when the tip of the odontoid trespassed the Chamberlain’s line in three different thresholds found in the literature: 2, 5 or 6.6 mm. In the surgical group (SU, the mean distance of the tip of the odontoid process above the Chamberlain’s line was 12 mm versus 1.2 mm in the control (CO group (p<0.0001. The number of patients with BI according to the threshold used (2, 5 or 6.6 mm in the SU group was respectively 19 (95%, 16 (80% and 15 (75% and in the CO group it was 15 (37%, 4 (10% and 2 (5%.

  1. Computational Fluid Dynamics modeling of contrast transport in basilar aneurysms following flow-altering surgeries.

    Science.gov (United States)

    Vali, Alireza; Abla, Adib A; Lawton, Michael T; Saloner, David; Rayz, Vitaliy L

    2017-01-04

    In vivo measurement of blood velocity fields and flow descriptors remains challenging due to image artifacts and limited resolution of current imaging methods; however, in vivo imaging data can be used to inform and validate patient-specific computational fluid dynamics (CFD) models. Image-based CFD can be particularly useful for planning surgical interventions in complicated cases such as fusiform aneurysms of the basilar artery, where it is crucial to alter pathological hemodynamics while preserving flow to the distal vasculature. In this study, patient-specific CFD modeling was conducted for two basilar aneurysm patients considered for surgical treatment. In addition to velocity fields, transport of contrast agent was simulated for the preoperative and postoperative conditions using two approaches. The transport of a virtual contrast passively following the flow streamlines was simulated to predict post-surgical flow regions prone to thrombus deposition. In addition, the transport of a mixture of blood with an iodine-based contrast agent was modeled to compare and verify the CFD results with X-ray angiograms. The CFD-predicted patterns of contrast flow were qualitatively compared to in vivo X-ray angiograms acquired before and after the intervention. The results suggest that the mixture modeling approach, accounting for the flow rates and properties of the contrast injection, is in better agreement with the X-ray angiography data. The virtual contrast modeling assessed the residence time based on flow patterns unaffected by the injection procedure, which makes the virtual contrast modeling approach better suited for prediction of thrombus deposition, which is not limited to the peri-procedural state.

  2. Spontaneous regression of a giant basilar artery aneurysm in a young adult after surgical injury:case report and literature review

    Institute of Scientific and Technical Information of China (English)

    ZHANG He; LI Ming-hua; WANG Chun; LI Yong-dong; XU Tao

    2007-01-01

    A giant basilar artery aneurysm of young woman with endocrine disturbance was misdiagnosed as a large pituitary adenoma and treated surgically via a trans-sphenoidal approach was planned.But the neurosurgery was finally aborted because of massive bleeding during the procedure. One year later, a cerebral angiography confirmed this basilar artery aneurysm was obviously regressed and then endovascular coiling was successfully performed. No neurological complication occurred post-procedure and the endocrine dysfunction symptom was obviously improved.

  3. [Endovascular treatment of critical basilar stenosis with a Solitaire® stent device: a first experience in our centre].

    Science.gov (United States)

    Mulero, Patricia; Cortijo-García, Elisa; Ruiz-Piñero, Marina; Pérez-Fernández, Santiago; Arenillas-Lara, Juan F; Martínez-Galdámez, Mario

    2014-08-01

    Introduccion. Aunque la arterioesclerosis intracraneal es una causa importante de ictus, la actitud terapeutica no esta claramente establecida. En este sentido, el estudio SAMMPRIS comparo el tratamiento medico intensivo con la angioplastia y colocacion de stent, con resultados favorables al tratamiento farmacologico. Estos resultados podrian, en parte, deberse al dispositivo utilizado (stent Wingspan ®). Caso clinico. Varon de 71 años con una estenosis grave de la arteria basilar, en quien se repetian episodios de focalidad neurologica transitoria a pesar del tratamiento con doble antiagregacion y estatinas. En estas circunstancias se decidio realizar una arteriografia terapeutica con angioplastia y colocacion de un stent Solitaire ® para optimizar resultados y se logro una estenosis residual del 40%. La evolucion fue favorable y los controles posteriores muestran una minima progresion. Conclusion. Segun nuestro conocimiento, este es el primer caso publicado de tratamiento de una estenosis critica de la arteria basilar mediante la colocacion de un stent Solitaire ®.

  4. Clinical characteristics of basilar artery syndrome%基底动脉尖综合征的临床特点

    Institute of Scientific and Technical Information of China (English)

    成亚琴

    2013-01-01

    Objective To investigate the clinical manifestations and imaging characteristics of the basilar artery syndrome. Methods A retrospective analysis of 32 cases with acute basilar artery syndrome was made. Results The patients were all acute onset with dizziness and vomiting in 12 cases,blurred vision in 3 cases, slurred speech in 14 cases, disturbance of consciousness in 16 cases, lmb paralysis in 14 case, unsteady gait in 5 cases, and headache and vomiting in 1 case. Multiple lesions were seen on the cerebral imagings in all patients. Conclusion The clinical manifestations of the basilar artery syndrome are veriable and complex with mild paralysis. MRI is helpful in the early diagnosis of the basilar artery syndrome.%目的 探讨基底动脉尖综合征的临床表现及影像学特点.方法 回顾性分析32例急性基底动脉尖综合征患者的临床资料.结果 32例患者均为急性起病,临床表现为眩晕、呕吐12例,视物不清3例,言语不清14例,意识障碍16例,肢体瘫痪14例,行走不稳5例,起病时仅感头痛、呕吐1例.所有患者头颅影像学检查均发现多发性病灶.结论 基底动脉尖综合征临床表现复杂多样,瘫痪程度较轻,MRI成像有助于早期确诊.

  5. Chronic basilar artery dissection with an associated symptomatic aneurysm presenting with massive subarachnoid hemorrhage.

    Science.gov (United States)

    Cohen, José E; Moscovici, Samuel; Rajz, Gustavo; Vargas, Andres; Itshayek, Eyal

    2016-08-01

    Basilar artery dissection (BAD) is a rare condition with a worse prognosis than a dissection limited to the vertebral artery. We report a rare case of chronic BAD with an associated symptomatic aneurysm presenting with massive subarachnoid hemorrhage (SAH) in a 54-year-old woman. The diagnosis of acute BAD could only be made retrospectively, based on clinical and neuroradiological studies from a hospital admission 10months earlier. Angiography performed after her SAH showed unequivocal signs of imperfect healing; she was either post-recanalization of a complete occlusion or post-dissection. Residual multi-channel intraluminal defects led to the development of a small aneurysm, which was responsible for the massive hemorrhage. The occurrence of an associated aneurysm, and wall disease, but not an intraluminal process, reinforces the diagnosis of dissection. The patient was fully recovered at 90day follow-up. This case reinforces the need for long-term neuroradiological surveillance after non-hemorrhagic intracranial dissections to detect the development of de novo aneurysms.

  6. Double-barrel Y-configuration stenting for flow diversion of a giant recurrent basilar apex aneurysm with the pipeline flex embolization device

    Directory of Open Access Journals (Sweden)

    Dale Ding

    2016-01-01

    Full Text Available Giant basilar apex aneurysms are extremely challenging to successfully manage. The Pipeline Flex embolization device (PFED is a new generation flow-diverting stent with a modified delivery system which allows resheathing of the stent after partial deployment. We describe a case of double-barrel Y-configuration stenting of a giant, recurrent basilar apex aneurysm using the PFED. A 73-year-old male was previously treated for an unruptured 11-mm basilar apex aneurysm with stent-assisted coiling using a Neuroform stent. The aneurysm was retreated twice with repeat coiling. After the third recurrence and persistent aneurysm growth into a giant, symptomatic lesion, we decided to proceed with flow diversion. We performed Y-stenting of the basilar bifurcation using three PFEDs, and was recoiled the aneurysm sac. Due to the low porosity of the flow diverters, a side-by-side double-barrel configuration was necessary in the basilar artery. Without the PFED's resheathable capability, it would not have been possible to perform Y-stenting with flow diverters.

  7. Double-barrel Y-configuration Stenting for Flow Diversion of a Giant Recurrent Basilar Apex Aneurysm with the Pipeline Flex Embolization Device.

    Science.gov (United States)

    Ding, Dale; Starke, Robert M; McGuinness, Ben; Brew, Stefan

    2016-12-01

    Giant basilar apex aneurysms are extremely challenging to successfully manage. The Pipeline Flex embolization device (PFED) is a new generation flow-diverting stent with a modified delivery system which allows resheathing of the stent after partial deployment. We describe a case of double-barrel Y-configuration stenting of a giant, recurrent basilar apex aneurysm using the PFED. A 73-year-old male was previously treated for an unruptured 11-mm basilar apex aneurysm with stent-assisted coiling using a Neuroform stent. The aneurysm was retreated twice with repeat coiling. After the third recurrence and persistent aneurysm growth into a giant, symptomatic lesion, we decided to proceed with flow diversion. We performed Y-stenting of the basilar bifurcation using three PFEDs, and was recoiled the aneurysm sac. Due to the low porosity of the flow diverters, a side-by-side double-barrel configuration was necessary in the basilar artery. Without the PFED's resheathable capability, it would not have been possible to perform Y-stenting with flow diverters.

  8. Alteration of Basilar Artery Rho-Kinase and Soluble Guanylyl Cyclase Protein Expression in a Rat Model of Cerebral Vasospasm following Subarachnoid Hemorrhage

    Directory of Open Access Journals (Sweden)

    Chih-Jen Wang

    2014-01-01

    Full Text Available Background and Purpose. The vasoconstrictor endothelin-1 (ET-1 has been implicated in the pathogenesis of cerebral vasospasm following subarachnoid hemorrhage (SAH. Previous results showed that CGS 26303, an endothelin converting enzyme (ECE inhibitor, effectively prevented and reversed arterial narrowing in animal models of SAH. In the present study, we assessed the effect of CGS 26303 on neurological deficits in SAH rats. The involvement of vasoactive pathways downstream of ET-1 signaling in SAH was also investigated. Methods. Sprague-Dawley rats were divided into five groups (n=6/group: (1 normal control, (2 SAH, (3 SAH+vehicle, (4 SAH+CGS 26303 (prevention, and (5 SAH+CGS 26303 (reversal. SAH was induced by injecting autologous blood into cisterna magna. CGS 26303 (10 mg/kg was injected intravenously at 1 and 24 hr after the initiation of SAH in the prevention and reversal protocols, respectively. Behavioral changes were assessed at 48 hr after SAH. Protein expression was analyzed by Western blots. Results. Deficits in motor function were obvious in the SAH rats, and CGS 26303 significantly improved the rate of paraplegia. Expressions of rho-kinase-II and membrane-bound protein kinase C-δ and rhoA were significantly increased, while those of soluble guanylyl cyclase α1 and β1 as well as protein kinase G were significantly decreased in the basilar artery of SAH rats. Treatment with CGS 26303 nearly normalized these effects. Conclusions. These results demonstrate that the rhoA/rho-kinase and sGC/cGMP/PKG pathways play pivotal roles in cerebral vasospasm after SAH. It also shows that ECE inhibition is an effective strategy for the treatment of this disease.

  9. A new procedure for automatic fitting of the basilar-membrane input-output function to individual behavioral data

    DEFF Research Database (Denmark)

    Kowalewski, Borys; Fereczkowski, Michal; MacDonald, Ewen;

    2016-01-01

    system and, potentially, for clinical diagnostics. Computational algorithms are available that mimic the functioning of the nonlinear cochlear processing. One such algorithm is the dual resonance non-linear (DRNL) filterbank [6]. Its parameters can be modified to account for individual hearing loss, e...... parameters is difficult. Until recently, the parameters were manually adjusted and the fitting process was indirect. A new approach is described here, based on a search through a lookup table of pre-computed filterbank input-output functions. The aim of this approach is to provide a fast, stable, and more...

  10. Hyperdense basilar artery sign diagnoses acute posterior circulation stroke and predicts short-term outcome

    Energy Technology Data Exchange (ETDEWEB)

    Tan, Xiaoping [Affiliated Hospital of China Medical University at Shenyang, Department of Neurology, Shengjing Hospital, Shenyang (China); Guo, Yang [Shengjing Hospital, Department of Neurology, Shenyang (China)

    2010-12-15

    It is well established that the hyperdense middle cerebral artery sign is a specific marker for early ischemia in anterior circulation. However, little is known about the hyperdense basilar artery sign (HDBA) in posterior circulation. Our aim was to determine whether the HDBA sign has utility in early diagnosis of acute posterior circulation stroke and prediction of short-term outcome. Three-blinded readers examined unenhanced computed tomography scans for the HDBA sign, and materials were classified into two groups according to this sign. Vascular risk factors, admission and discharge National Institute of Health Stroke Scale (NIHSS) scores, short-term outcome, and radiological findings between the two groups were compared. One hundred and twenty-six cases of acute posterior circulation stroke (PCS) were included in the study. No statistically significant differences were found in risk factors of ischemic stroke, except atrial fibrillation (P = 0.025). Admission and discharge NIHSS scores for the positive HDBA group were significantly higher than scores for the negative HDBA group (P = 0.001, 0.002, respectively). The infarction territory for the positive HDBA group was mainly multi-region in nature (51.6%, P < 0.001), while the negative HDBA group showed mainly middle territory infarction. Significant independent predictors of short-term outcome included the HDBA sign (P < 0.001) and admission NIHSS scores (P < 0.001). Approximately half of the HDBA patients showed multi-region infarction and a serious neurological symptom. Based on our results, this sign might not only be helpful in early diagnosis of acute PCS but also be able to correlate with a poor short-term outcome. (orig.)

  11. Vertebro-basilar junction aneurysms: a single centre experience and meta-analysis of endovascular treatments.

    Science.gov (United States)

    Graziano, Francesca; Ganau, Mario; Iacopino, Domenico Gerardo; Boccardi, Edoardo

    2014-12-01

    Vascular lesions of the vertebrobasilar junction (VBJ) are challenging in neurosurgical practice, and their gold-standard therapy is still under debate. We describe the operative strategies currently in use for the management of these complex vascular lesions and discuss their rationale in a literature meta-analysis and single centre blinded retrospective study. The single centre study included a review of initial presentation, angiographic features and clinical outcome (with modified Rankin Scale [mRS] scores) over a long-term follow-up. In our series, small aneurysms were effectively treated by endosaccular coil embolization, whereas a strategy including flow-diverter devices combined with endosaccular coil embolization was the option of choice in large and giant aneurysms, leading to satisfactory outcomes in most cases. Our Medline review showed that endovascular treatment was chosen in most VBJ cases, whereas the microsurgical option was assigned to only a few cases. Among the endovascular treatments, the most common techniques used for the treatment of VBJ aneurysms were: coiling, stent-assisted coiling and flow diversion. Our study highlights that aneurysm morphology, location and patient-specific angio-architecture are key factors to be considered in the management of VBJ aneurysms. Most case series, including our own, show that parent artery reconstruction using a flow-diverter device is a feasible and successful technique in some cases of giant and complex aneurysms (especially those involving the lower third of the basilar artery) while a "sit back, wait and see" approach may represent the safest and most reasonable option.

  12. Potassium currents in auditory hair cells of the frog basilar papilla.

    Science.gov (United States)

    Smotherman, M S; Narins, P M

    1999-06-01

    The whole-cell patch-clamp technique was used to identify and characterize ionic currents in isolated hair cells of the leopard frog basilar papilla (BP). This end organ is responsible for encoding the upper limits of a frog's spectral sensitivity (1.25-2.0 kHz in the leopard frog). Isolated BP hair cells are the smallest hair cells in the frog auditory system, with spherical cell bodies typically less than 20 microm in diameter and exhibiting whole-cell capacitances of 4-7 pF. Hair cell zero-current resting potentials (Vz) varied around a mean of -65 mV. All hair cells possessed a non-inactivating, voltage-dependent calcium current (I(Ca)) that activates above a threshold of -55 mV. Similarly all hair cells possessed a rapidly activating, outward, calcium-dependent potassium current (I(K)(Ca)). Most hair cells also possessed a slowly activating, outward, voltage-dependent potassium current (I(K)), which is approximately 80% inactive at the hair cell Vz, and a fast-activating, inward-rectifying potassium current (I(K1)) which actively contributes to setting Vz. In a small subset of cells I(K) was replaced by a fast-inactivating, voltage-dependent potassium current (I(A)), which strongly resembled the A-current observed in hair cells of the frog sacculus and amphibian papilla. Most cells have very similar ionic currents, suggesting that the BP consists largely of one homogeneous population of hair cells. The kinetic properties of the ionic currents present (in particular the very slow I(K)) argue against electrical tuning, a specialized spectral filtering mechanism reported in the hair cells of birds, reptiles, and amphibians, as a contributor to frequency selectivity of this organ. Instead BP hair cells reflect a generalized strategy for the encoding of high-frequency auditory information in a primitive, mechanically tuned, terrestrial vertebrate auditory organ.

  13. Espasmo hemifacial e impressão basilar associados a malformação de arnold-chiari relato de caso

    OpenAIRE

    Manoel Baldoino Leal Filho; Elza Dias-Tosta; Nasser Allan; Paulo Said; José Luis F. Mendonça; Fernando Guilhon Henriques

    1992-01-01

    Os autores relatam o caso de uma paciente com espasmo hemifacial e impressão basilar associados a malformação de Arnold-Chiari. Com a descompressão cirúrgica da fossa posterior, empregada no tratamento da impressão basilar, houve melhora do quadro clínico e o espasmo hemifacial se reduziu quanto à frequência, duração e intensidade. É enfatizada a necessidade do tratamento etiológico do espasmo hemifacial, antes de se recorrer à toxina botulínica.

  14. Espasmo hemifacial e impressão basilar associados a malformação de arnold-chiari relato de caso

    Directory of Open Access Journals (Sweden)

    Manoel Baldoino Leal Filho

    1992-09-01

    Full Text Available Os autores relatam o caso de uma paciente com espasmo hemifacial e impressão basilar associados a malformação de Arnold-Chiari. Com a descompressão cirúrgica da fossa posterior, empregada no tratamento da impressão basilar, houve melhora do quadro clínico e o espasmo hemifacial se reduziu quanto à frequência, duração e intensidade. É enfatizada a necessidade do tratamento etiológico do espasmo hemifacial, antes de se recorrer à toxina botulínica.

  15. Sequential combination of two intravenous thrombolytics (recombinant tissue plasminogen activator/tenecteplase) in a patient with stroke and cardioembolic basilar artery occlusion.

    Science.gov (United States)

    Smadja, Didier; Olindo, Stéphane; Saint-Vil, Martine; Chausson, Nicolas

    2009-01-01

    Stroke caused by acute occlusion of basilar artery (AOBA) produces high risk of death. In eligible patients, thrombolysis significantly reduces mortality and disability rate. In most hospitals, thrombolysis is limited to intravenous (IV) route of recombinant tissue plasminogen activator, without any therapeutic alternative in cases of treatment failure. We report a case of cardioembolic AOBA, not responsive to a conventional regimen of IV recombinant tissue plasminogen activator. A sequential combination of IV tenecteplase (0.4 mg/kg) led to a complete recanalization of basilar artery, with a very good clinical outcome. The potential for a combination of two successive IV regimens should be evaluated in AOBA.

  16. Basilar Artery Territory Stroke Secondary to Invasive Fungal Sphenoid Sinusitis: A Case Report and Review of the Literature

    Directory of Open Access Journals (Sweden)

    Katherine A. Fu

    2015-03-01

    Full Text Available Background: Mucormycosis is a fungal infection with the following 5 classic forms: cutaneous, pulmonary, gastrointestinal, disseminated, and rhinocerebral. The rhinocerebral form can be rapidly progressive and invasive with a high mortality rate. We present a case of a 38-year-old man with invasive mucormycosis that led to a basilar artery territory stroke. Rhinocerebral mucormycosis is an unusual cause of stroke. Case Report: A 38-year-old man with a past medical history of diabetes mellitus presented with altered mental status. A lumbar puncture revealed eosinophilic pleocytosis with a mildly elevated total protein and borderline low glucose level. CT revealed a left medullary and cerebellar infarct confirmed by MRI. MRI also displayed a diffuse marrow signal abnormality in the clivus with contiguous sinus disease. Endoscopic sinus surgery confirmed that the fungal sinusitis was mucormycosis of the Rhizopus genus, which had affected the left sphenoid sinus, invaded through the skull base, and involved the basilar artery. He was given liposomal amphotericin (500 mg i.v. with posaconazole (400 mg i.v. twice daily. Due to the severity of the invasion and poor prognosis, the patient was discharged with comfort care measures. Discussion: Clinicians should be aware of invasive sinusitis as a rare cause of stroke in diabetics. Once the subarachnoid space and basal arteries of the brain have been invaded, the prognosis is very poor. The key to improvement of outcomes is early recognition and treatment, and examination of the sinuses on neuroimaging in all cases of stroke is vital.

  17. [Cyclothymia and the brain stem. The question of symptomatic cyclothymia on the basis of observations in insufficiency of the basilar arterial system].

    Science.gov (United States)

    Marneros, A; Philipp, M

    1978-01-01

    Seven patients with an insufficiency in the basilar arterial system showed a typical endogenous depression. We assumed that the temporal coincidence of neurological and psychial syndromes was not accidental but both were caused by a circulation disturbance in the cerebral stem structures.

  18. Hypercapnic vasodilatation in isolated rat basilar arteries is exerted via low pH and does not involve nitric oxide synthase stimulation or cyclic GMP production

    DEFF Research Database (Denmark)

    You, J P; Wang, Qian; Zhang, W;

    1994-01-01

    The relaxant effect of hypercapnia (15% CO2) was studied in isolated circular segments of rat basilar arteries with intact endothelium. The nitric oxide synthase inhibitor nitro-L-arginine (L-NOARG) and the cytosolic guanylate cyclase inhibitor methylene blue (MB), significantly reduced...

  19. 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...

  20. Posterior fossa decompression with tonsillectomy in 104 cases of basilar impression, Chiari malformation and/or syringomyelia

    Directory of Open Access Journals (Sweden)

    José Alberto Gonçalves da Silva

    2011-10-01

    Full Text Available The prime objective in the surgical treatment of basilar impression (BI, Chiari malformation (CM and/or syringomyelia (SM is based on the restoration of the normal cerebrospinal fluid (CSF dynamics at the craniovertebral junction through the creation of a large artificial cisterna magna. A small suboccipital craniectomy has been emphasized to avoid caudal migration of the hindbrain structures into the vertebral canal. Nevertheless, the results showed downward migration of the hindbrain related to that type of craniectomy. The authors present, otherwise, the results of 104 cases of BI, CM and/or SM, whose surgical treatment was characterized by a large craniectomy with the patient in the sitting position, tonsillectomy, large opening of the fourth ventricle and duraplasty with creation of a large artificial cisterna magna. A significant upward migration of the posterior fossa structures was detected by postoperative magnetic resonance imaging.

  1. Vanillin and vanillin analogs relax porcine coronary and basilar arteries by inhibiting L-type Ca2+ channels.

    Science.gov (United States)

    Raffai, Gábor; Khang, Gilson; Vanhoutte, Paul M

    2015-01-01

    Vanillin (VA) and vanillyl alcohol (VAA), components of natural vanilla, and ethyl vanillin (EtVA; synthetic analog) are used as flavoring agents and/or as additives by the food, cosmetic, or pharmaceutic industries. VA, VAA, and EtVA possess antioxidant and anti-inflammatory properties, but their vascular effects have not been determined. Therefore, we compared in isolated porcine coronary and basilar arteries the changes in isometric tension caused by VA, VAA, and EtVA. VA and its analogs caused concentration-dependent relaxations of both preparations during contractions from U46619 (9,11-dideoxy-11α,9α-epoxymethanoprostaglandin F2α, a thromboxane A2 receptor agonist), and of coronary arteries contracted with KCl or endothelin-1. The order of potency was VAA vanillin additives.

  2. Enhancing hippocampal blood flow after cerebral ischemia and vasodilating basilar arteries: in vivo and in vitro neuroprotective effect of antihypertensive DDPH

    Directory of Open Access Journals (Sweden)

    Li Sun

    2015-01-01

    Full Text Available 1-(2,6-Dimethylphenoxy-2-(3,4-dimethoxyphenylethylamino-propane hydrochloride (DDPH is a novel antihypertensive agent based on structural characteristics of mexiletine and verapamine. We investigated the effect of DDPH on vasodilatation and neuroprotection in a rat model of cerebral ischemia in vivo, and a rabbit model of isolated basilar arteries in vitro. Our results show that DDPH (10 mg/kg significantly increased hippocampal blood flow in vivo in cerebral ischemic rats, and exerted dose-dependent relaxation of isolated basilar arteries contracted by histamine or KCl in the in vitro rabbit model. DDPH (3 × 10 -5 M also inhibited histamine-stimulated extracellular calcium influx and intracellular calcium release. Our findings suggest that DDPH has a vasodilative effect both in vivo and in vitro, which mediates a neuroprotective effect on ischemic nerve tissue.

  3. enhancing hippocampal blood lfow after cerebral ischemia and vasodilating basilar arteries:in vivo andin vitro neuroprotective effect of antihypertensive DDPH

    Institute of Scientific and Technical Information of China (English)

    Li Sun; Qin Li; Wei-ting Wang; Yu-hua Chen; Lian-jun Guo

    2015-01-01

    1-(2,6-Dimethylphenoxy)-2-(3,4-dimethoxyphenylethylamino)-propane hydrochloride (DDPH) is a novel antihypertensive agent based on structural characteristics of mexiletine and verapamine. We investigated the effect of DDPH on vasodilatation and neuroprotection in a rat model of cerebral ischemiain vivo, and a rabbit model of isolated basilar arteriesin vitro. Our results show that DDPH (10 mg/kg) significantly increased hippocampal blood flowin vivo in cerebral ischemic rats, and exerted dose-dependent relaxation of isolated basilar arteries contracted by histamine or KCl in thein vitro rabbit model. DDPH (3 × 10–5 M) also inhibited histamine-stimulated extracellular calcium inlfux and intracellular calcium release. Our ifndings suggest that DDPH has a vasodilative effect bothin vivo andin vitro, which mediates a neuropro-tective effect on ischemic nerve tissue.

  4. Locked-in syndrome in a patient with acute obstructive hydrocephalus, caused by large unruptured aneurysm of the basilar artery (BA).

    Science.gov (United States)

    Kolić, Zlatko; Kukuljan, Melita; Vukas, Duje; Bonifačić, David; Vrbanec, Kristina; Franić, Ivana Karla

    2016-09-15

    We describe a case of acute obstructive hydrocephalus as a consequence of compression of the brainstem by a large aneurysm of the basilar artery (BA) in a 62-year-old male. After the insertion of the ventriculoperitoneal shunt (VPS), we encountered the "locked-in syndrome" clinical condition. "Locked-in syndrome" is a clinical state characterized by quadriplegia and anarthria with preserved consciousness, most commonly caused by ischemia in the ventral part of pons.

  5. Posterior reduction and internal fixation with posterior cranial fossa cranioectomy decompression for Chiari malformation type Ⅰ with basilar invagination, atlantoaxial subluxation, and syringomyelia

    Directory of Open Access Journals (Sweden)

    HU Peng

    2012-08-01

    Full Text Available Background Chiari malformation type Ⅰ(CM-Ⅰ is one of the soft tissue anomalies in craniovertebral junction (CVJ. This kind of soft tissue anomaly usually develops with bone anomaly, such as atlantoaxial subluxation, basilar invagination, platybasia, C1 assimilation, etc. For these complex combined anomalies, the treatment remains unaddressed. This study was performed to evaluate the effect of posterior reduction and internal fixation with posterior cranial fossa cranioectomy decompression for Chiari malformation type Ⅰ with basilar invagination, atlantoaxial subluxation, and syringomyelia. Methods Patients with basilar invagination and atlantoaxial subluxation treated from July 2004 to September 2011 were reviewed. Including criterions were made to screen matching patients. Including patients were retrospectively analyzed on both clinical outcomes and radiographical results. Japanese Orthopaedic Association (JOA score was used to evaluate the clinical outcomes, while the syrinx maximum size was measured on transverse view of MRI T2 image. The results were analyzed by SPSS 17.0 using t -text. Significant difference was considered when P ≤ 0.05. Results Fourteen patients met the including criterions, including 4 male patients and 10 female patients, with a mean age of 31.86 ± 11.36 (standard deviation, range: 17-51 years. Mean JOA score preoperatively of 14 patients was 13.07 ± 1.59 (standard deviation, while that was 15.57 ± 1.02 (standard deviation postoperatively (t = 9.946, P = 0.000. The mean syrinx size was (7.05 ± 1.98 mm (standard deviation, while that was (2.21 ± 1.91 mm (standard deviation postoperatively (t = 7.271, P = 0.000. There were no procedure-related morbidity or mortality happened. Conclusion Direct posterior reduction and internal fixation with posterior cranial fossa cranioectomy decompression can obviously improve the clinical outcomes and shrink syrinx for patients suffered from Chiari malformation typeⅠ with

  6. Ruptured aneurysm at the cortical segment of the distal posterior inferior cerebellar artery associated with hemodynamic stress after basilar artery occlusion

    Directory of Open Access Journals (Sweden)

    Akiko Marutani

    2016-01-01

    Conclusion: This report describes a case of de novo development of a saccular distal PICA aneurysm after atherosclerotic basilar artery occlusion. We believe that increased hemodynamic stress at the PICA might have contributed to the occurrence and rupture of the aneurysm. STA-SCA bypass, introduced in the territory of the cerebellar hemisphere, reduces hemodynamic stress, which would prevent the occurrence of de novo aneurysm and recurrent bleeding.

  7. Combined extracranial-intracranial bypass surgery with stent-assisted coil embolization for moyamoya disease with a ruptured wide-necked basilar trunk aneurysm: a case report.

    Science.gov (United States)

    Jiang, Hanqiang; Ni, Wei; Lei, Yu; Li, Yanjiang; Gu, Yuxiang

    2015-01-01

    A ruptured wide-necked basilar trunk aneurysm is uncommon in patients with moyamoya disease. The optimal treatment is unclear. We report a safe and beneficial treatment modality for moyamoya disease with aneurysms located in the posterior circulation. A 37-year-old man presenting with subarachnoid hemorrhage was admitted to our hospital. Emergent cerebral angiography demonstrated moyamoya disease associated with a wide-necked basilar trunk aneurysm. We performed bilateral extracranial-intracranial bypass surgeries prior to stent-assisted coil embolization of the aneurysm after the acute phase. No complication occurred and the patient was discharged with no neurological deficit. Follow-up digital subtraction angiography (DSA) performed 6 months after the surgery showed that all the anastomosises were patent and bilateral collateral vascular compensation was fully established with no recanalization of the basilar trunk aneurysm post embolization.We also found that high-flow bypass did not contribute to cerebral revascularization as imagined despite the good patency. Combined extracranial-intracranial bypass surgery with endovascular treatment proved to be an efficient therapeutic modality for moyamoya disease with aneurysms located in the posterior circulation. High-flow bypass surgery was not essential due to the inefficiency and the high risk of postoperative cerebral hyperperfusion syndrome.

  8. 基底动脉发育不良影像学特征%Imaging characteristics of basilar artery hypoplasia

    Institute of Scientific and Technical Information of China (English)

    顾华; 钱晓军; 王双坤; 闵小红; 鲁万红; 胡文立

    2014-01-01

    目的 研究基底动脉发育不良(BAH)的影像学特征.方法 回顾2009年10月至2013年8月在首都医科大学附属北京朝阳医院进行MRA和MRI检查的连续病例.根据BAH诊断标准共检出210例BAH,测量(椎)基底动脉直径.根据诊断标准急性脑梗死分成前循环和后循环梗死.结果 10 193例MRA中检出210例BAH,女性多于男性.BAH伴有双侧胚胎型大脑后动脉175例(83.3%),单侧35例(16.7%).99.5% BAH患者伴有V4段椎动脉发育不良;颈段(V1 ~V3)椎动脉发育不良占56.0%(28/50).210例中74例合并急性脑梗死,男性多于女性(59.5%比40.5%,P=0.021).急性脑梗死中BAH的发病率是2.2%(74/3 294).结论 BAH是较少见的脑血管发育异常,伴有胚胎型大脑后动脉和V4段椎动脉发育不良.%Objective To determine the imaging characteristics of basilar artery hypoplasia (BAH).Methods From October 2009 to August 2013,10 193 magnetic resonance angiogram (MRA) and 31 716 magnetic resonance imaging (MRI) consecutive cases were retrospectively retrieved from our institutional Picture Archiving and Communication System (PACS) database.BAH was defined as a continuous diameter reduction all over artery and a basilar artery diameter ≤2 mm.The same cut-off value was applied for vertebral artery hypoplasia (VAH).We measured the diameters of basilar and vertebral arteries with PACS in all patients according to source imaging and IMP construction of MRA.The carotid arterial computed tomography angiogram (CTA) profiles were reviewed in 50 patients.The fetal-type posterior circle of Willis (FTP) was assessed.The diagnosis of acute cerebral infarction was based on clinical symptoms,signs and a high signal on diffusion-weighted imaging (DWI).Acute cerebral infarction was divided into anterior circulation stroke (ACS) and posterior circulation stroke (PCS).Results A total of 210 BAH were identified among 10 193 consecutive patients.BAH was more common in females (56.7%) than males

  9. 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....

  10. 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

  11. Endovascular Treatment of the Huge Dissecting Aneurysms Involving the Basilar Artery by the Internal Trapping Technique: Technical Note

    Institute of Scientific and Technical Information of China (English)

    Shi-Qing Mu; Xin-Jian Yang; You-Xiang Li; Chu-Han Jiang; Zhong-Xue Wu

    2015-01-01

    Background:The endovascular strategy of the huge dissecting aneurysms involving the basilar artery (BA) is controversial and challenging.This study was to investigate the clinical and angiographic outcomes of the treatment of the huge dissecting aneurysms involving the BA by the internal trapping (IT) technique.Methods:We retrospectively studied 15 patients with the huge dissecting aneurysms involving the BA treated by the IT technique between September 2005 and September 2014 in Department of lnterventional Neuroradiology of Beijing Tiantan Hospital.Clinical and angiographic data were reviewed and evaluated.Results:All patients were treated by the IT technique.That meant the dissecting artery and aneurysm segments were completed occlusion.After the procedure,the angiography demonstrated that all the dissecting artery and aneurysm segments were completed occlusion.Follow-up angiography was performed at 3-6 months or 12-18 months after the endovascular treatment (median 8 months),14 patients had a good recovery.Re-canalization occurred in one patient whose aneurysm involved in bilateral vertebral arteries and the two third of the middle-lower BA.After the second treatment,the patient died by the ventricular tachycardia.Conclusions:The IT technique is a technically feasible and safe alternative for the treatment of BA dissecting aneurysms,but it is not necessarily the safest or most definitive treatment modality.The ideal treatment of the huge dissecting aneurysms involving the BA remains debatable and must be investigated on a case-by-case basis.

  12. Endovascular Treatment of the Huge Dissecting Aneurysms Involving the Basilar Artery by the Internal Trapping Technique: Technical Note

    Directory of Open Access Journals (Sweden)

    Shi-Qing Mu

    2015-01-01

    Full Text Available Background: The endovascular strategy of the huge dissecting aneurysms involving the basilar artery (BA is controversial and challenging. This study was to investigate the clinical and angiographic outcomes of the treatment of the huge dissecting aneurysms involving the BA by the internal trapping (IT technique. Methods: We retrospectively studied 15 patients with the huge dissecting aneurysms involving the BA treated by the IT technique between September 2005 and September 2014 in Department of Interventional Neuroradiology of Beijing Tiantan Hospital. Clinical and angiographic data were reviewed and evaluated. Results: All patients were treated by the IT technique. That meant the dissecting artery and aneurysm segments were completed occlusion. After the procedure, the angiography demonstrated that all the dissecting artery and aneurysm segments were completed occlusion. Follow-up angiography was performed at 3-6 months or 12-18 months after the endovascular treatment (median 8 months, 14 patients had a good recovery. Re-canalization occurred in one patient whose aneurysm involved in bilateral vertebral arteries and the two third of the middle-lower BA. After the second treatment, the patient died by the ventricular tachycardia. Conclusions: The IT technique is a technically feasible and safe alternative for the treatment of BA dissecting aneurysms, but it is not necessarily the safest or most definitive treatment modality. The ideal treatment of the huge dissecting aneurysms involving the BA remains debatable and must be investigated on a case-by-case basis.

  13. Evaluation of the Effects of Sildenafil Citrate (Viagra) on Vertebral Artery Blood Flow in Patients with Vertebro-Basilar Insufficiency

    Energy Technology Data Exchange (ETDEWEB)

    Bozgeyik, Zulkif; Berilgen, Sait; Ozdemir, Huseyin; Ogur, Erkin [Firat University School of Medicine, Elazig(Turkmenistan); Tekatas, Aslan [Elazig Government Hospital, Elazig (Turkmenistan)

    2008-12-15

    To investigate the effects of sildenafil citrate (Viagra) on the vertebral artery blood flow of patients with vertebro-basilar insufficiency (VBI) using color duplex sonography (CDS). The study included 21 patients with VBI (aged 31-76; mean 61.0 +- 10.5 yrs). We administered a 50 mg oral dose of sildenafil citrate to all patients. Next, we measured the peak systolic velocity (Vmax), end diastolic velocity (Vmin), resistive index (RI), pulsatility index (PI), diameter, area, and flow volume (FV) of vertebral arteries using CDS before the administration of sildenafil citrate; 45 minutes after, and 75 minutes after administration. Statistical testing was performed using SPSS for windows version 11.0. The statistical test used to determine the outcome of the analysis was the repeated measures analysis of variance (ANOVA) test. Compared to the baseline values, the vertebral artery diameter, area, and FV increased significantly following the administration of sildenafil citrate. The diameter, area and FV increased from 3.39 mm at 45 minutes to 3.64 mm at 75 minutes, 9.43 cm{sup 2} to 10.80 cm{sup 2} at 45 minutes and 10.81 cm{sup 2} at 75 minutes, as well as from 0.07 L/min at baseline to 0.09 L/min at 45 minutes and unchanged at 75 minutes, respectively. Sildenafil citrate elicited a significant effect on vertebral artery diameter, area and FVs

  14. Comparison between distortion product otoacoustic emissions and nerve fiber responses from the basilar papilla of the frog

    Science.gov (United States)

    Meenderink, Sebastiaan W. F.; van Dijk, Pim; Narins, Peter M.

    2005-05-01

    The basilar papilla (BP) is one of the three end organs in the frog inner ear that is sensitive to airborne sound. Its anatomy and physiology are unique among all classes of vertebrates. Essentially, the BP functions as a single auditory filter presumably arising from a mechanically-tuned mechanism. As such, both neural and distortion product otoacoustic emission (DPOAE) tuning may reflect a single mechanical filtering mechanism. Using the Duffing oscillator as a simple model for both neural and DPOAE tuning from the BP, two predictions can be made: [1] the characteristic frequency (CF) of neural tuning and the best frequency (BF) of DPOAE tuning will coincide and [2] the neural tuning curve and DPOAE-audiogram have a similar shape when the neural tuning curve is scaled by a factor of 4 along the y-axis. We recorded both neural tuning curves and DPOAE-audiograms from the BP of the leopard frog. These recordings show good agreement with the model predictions when the stimulus tones are related by relatively small stimulus frequency ratios. For larger stimulus frequency ratios, DPOAE recordings clearly deviate from model predictions. These differences are most likely caused by the oversimplified representation of the frog BP by the model. .

  15. 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 ...

  16. 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

  17. Basilar impression, Chiari malformation and syringomyelia: a retrospective study of 53 surgically treated patients Impressão basilar, malformação de Chiari e siringomielia: estudo retrospecivo de 53 casos operados

    Directory of Open Access Journals (Sweden)

    José Alberto Gonçalves da Silva

    2003-06-01

    Full Text Available The present study shows the results of 53 patients who have been treated surgically for basilar impression (BI, Chiari malformation (CM, and syringomyelia (SM. The patients were divided into two groups. Group I (24 patients underwent osteodural decompression with large inferior occipital craniectomy, laminectomy from C 1 to C 3, dural opening in Y format, dissection of arachnoid adhesion between the cerebellar tonsils, medulla oblongata and spinal cord, large opening of the fourth ventricle and dural grafting with the use of bovine pericardium. Group II patients (29 patients underwent osteodural-neural decompression with the same procedures described above plus dissection of the arachnoid adherences of the vessels of the region of the cerebellar tonsils, and tonsillectomy (amputation in 10 cases, and as for the remainning 19 cases, intrapial aspiration of the cerebellar tonsils was performed. The residual pial sac was sutured to the dura in craniolateral position. After completion of the suture of the dural grafting, a thread was run through the graft at the level of the created cisterna magna and fixed to the cervical aponeurosis so as to move the dural graft on a posterior- caudal direction, avoiding, in this way, its adherence to the cerebellum.São analisados os resultados obtidos com o tratamento cirúrgico de 53 casos de impressão basilar (IB, malformação de Chiari (MC e siringomielia (SM. Os pacientes foram divididos em dois grupos: no grupo I (24 casos foi realizada a descompressão osteodural, caracterizada por craniectomia ampla occipital inferior, laminectomia variável de C 1 a C 3, abertura da dura-máter em forma de Y, dissecção das aderências aracnóideas das tonsilas cerebelares com o bulbo e medula cervical, abertura ampla do quarto ventrículo e enxerto dural; no grupo II (29 casos foi utilizada a descompressão osteodural-neural, caracterizada pelos mesmos detalhes técnicos empregados no grupo I, acrescidos da

  18. 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.

  19. Valor da linha bimastóidea de Fischgold e Metzger para o diagnóstico radiológico da impressão basilar

    Directory of Open Access Journals (Sweden)

    Horacio M. Canelas

    1956-12-01

    Full Text Available No sentido de precisar os valores normais da distância entre o ápice da apófise odontóide do áxis e a linha bimastóidea de Fischgold e Metzger - índice valioso para o diagnóstico radiológico de impressão basilar - os autores fazem o estudo estatístico das medidas realizadas em 127 craniogramas de pacientes sem malformações occípito-cervicais e em 11 casos de impressão basilar diagnosticada clínica e radiològicamente. São estudadas as correlações dessa distância com a idade e com a distância entre a ponta da odontóide e a linha basal de McGregor. Os autores concluem que: 1 Acima de 10 anos de idade, a média da distância entre a ponta odontóidea e a linha de Fischgold e Metzger é, normalmente, de +0,56 ± 5,79 mm, à qual correspondem os limites fiduciais de -10,79 e +11,91 mm. Logo, valores dessa distância superiores a 12 mm devem ser considerados como indício radiológico de impressão basilar. 2 Foi observada correlação entre os valores dessa distância e os da existente entre o ápice da odontóide e a linha basal de McGregor, em 120 casos normais, com mais de 10 anos de idade. 3 Não foi encontrada diferença entre as médias da distância entre extremidade do dente axóideo e a linha bimastóidea nos sexos masculino e feminino. 4 Pelo menos até 20 anos de idade, há correlação entre os valores desta distância e a idade. Logo, até essa idade, o diagnóstico de impressão basilar deve ser feito perante menores valores dessa distância, sendo de aproximadamente +8 mm o limite superior da normalidade. 5 Nos casos de impressão basilar a média da distância entre ponta odontóidea e a linha de Fischgold-Metzger foi de +21,09 ± 10,03 mm, significantemente maior que a encontrada nos casos sem malformação occipitocervical. 6 Não houve correlação entre o grau de impressão basilar e a idade, ou entre as distâncias entre a extremidade axóidea e as linhas de Fischgold-Metzger e de McGregor nos casos dessa

  20. Plaques of Nonstenotic Basilar Arteries with Isolated Pontine Infarction on Three-dimensional High Isotropic Resolution Magnetic Resonance Imaging

    Institute of Scientific and Technical Information of China (English)

    Xian-Jin Zhu; Wei-Jian Jiang; Lei Liu; Li-Bin Hu; Wu Wang; Zun-Jing Liu

    2015-01-01

    Background:There are few studies for evaluating plaque characteristics of nonstenotic basilar arteries (BA).Our aim was to determine entire BA plaques with a three-dimensional volumetric isotropic turbo spin-echo acquisition (VISTA) and investigate the differences between the patients with and without isolated pontine infarction (IPI).Methods:Twenty-four consecutive symptomatic patients with nonstenotic BA on time of flight magnetic resonance angiography (TOF MRA) were enrolled from China-Japan Friendship Hospital between January 2014 and December 2014.BA was classified as "normal" or"irregular" based on TOF MRA,and "normal wall","slight wall-thickening",and "plaque" based on three-dimensional VISTA images.Outcomes from MRA and VISTA were compared.Patients were categorized as IPI and non-IPI groups based on the diffusion-weighted imaging.Clinical and plaque characteristics were compared between the two groups.Results:A total of 1024 image slices including 311 (30.37%) plaque slices,427 (41.70%) slight wall-thickening slices,and 286 (27.93%) normal wall slices for the entire BA from 23 patients were finally included for analysis.VISTA images detected plaques in all the 9 (100%) irregular MRA patients and 7 of 14 (50%) normal MRA patients.IPI was found in 1 1 (47.83%) patients.Compared to non-IPI group,the IPI group had a higher percentage of plaque slices (P =0.001) and lower percentage of normal wall slices (P =0.014) than non-IPI group.Conclusions:Three-dimensional VISTA images enable detection of BA plaques not visualized by MRA.BA plaques could be found in both the IPI and non-IPI group.However,IPI group showed plaques more extensively in BA than the non-IPI group.

  1. One-off surgery of posterior reduction and fixation for the treatment of basilar invagination with atlantoaxial dislocation

    Directory of Open Access Journals (Sweden)

    LIU Jia-gang

    2012-08-01

    Full Text Available Objective To investigate the surgical treatment and clinical results for the primary basilar invagination (BI with atlantoaxial dislocation (AAD. Methods A retrospective study was performed. The study included 89 patients who had primary BI and AAD were surgically treated in our hospital from January 2008 to December 2011. There were 28 males and 61 females, aged between 10 and 69 years (mean 45.42 years. All patients were treated by the same 3-step surgical method. The first step, reduction of the AAD was performed by homemade odontoid repositor intraoperatively through posterior approach; the second step, AO stainless steel plates were fixed between the occiput and C2, 3 lateral mass screws; and the third step, occipitocervical fusion were completed by autologous iliac crest graft. Operation effect was recorded during follow-up period. Results Follow-up period was 6 to 48 months. Clinical symptoms were improved in 82.93% patients after the surgery. Japanse Orthopaedic Association (JOA score increased from preoperative (8.80 ± 1.36 points to postoperative (15.35 ± 1.47 points (t = 17.225, P = 0.001. In general, satisfactory decompression and bony fusion were shown on postoperative radiological examinations for all patients. Compared with pretreatment data, the postoperative imaging measurement showed that the mean data of atlanto-dental interval (ADI, 9.22 mm vs 3.72 mm and vertical dimension from the top of odontoid process to Chamberlain line (10.41 mm vs 3.23 mm were all reduced, and the cervicomedullary angle (130° vs 150° and space available of spinal cord (SAC, 11.13 mm vs 15.54 mm were all improved. Conclusion The one-off surgery of posterior reduction technique and fixing between occiput and C2, 3 lateral mass screws is a safe, easy, and effective treatment for patients with p

  2. EFFECTS OF RESTRICTED BASILAR PAPILLAR LESIONS AND HAIR CELL REGENERATION ON AUDITORY FOREBRAIN FREQUENCY ORGANIZATION IN ADULT EUROPEAN STARLINGS

    Science.gov (United States)

    Irvine, Dexter R. F.; Brown, Mel; Kamke, Marc R.; Rubel, Edwin W

    2009-01-01

    The frequency organization of neurons in the forebrain Field L complex (FLC) of adult starlings was investigated to determine the effects of hair cell (HC) destruction in the basal portion of the basilar papilla (BP) and of subsequent HC regeneration. Conventional microelectrode mapping techniques were used in normal starlings and in lesioned starlings either 2 days or 6–10 weeks after aminoglycoside treatment. Histological examination of the BP and recordings of auditory brainstem evoked responses confirmed massive loss of HCs in the basal portion of the BP and hearing losses at frequencies above 2 kHz in starlings tested 2 days after aminoglycoside treatment. In these birds, all neurons in the region of the FLC in which CFs normally increase from 2 to 6 kHz had characteristic frequency (CF) in the range 2–4 kHz. The significantly elevated thresholds of responses in this region of altered tonotopic organization indicated that they were the residue of pre-lesion responses and did not reflect central nervous system plasticity. In the long-term recovery birds, there was histological evidence of substantial HC regeneration. The tonotopic organization of the high frequency region of the FLC did not differ from that in normal starlings, but the mean threshold at CF in this frequency range was intermediate between the values in the normal and lesioned short-recovery groups. The recovery of normal tonotopicity indicates considerable stability of the topography of neuronal connections in the avian auditory system, but the residual loss of sensitivity suggests deficiencies in high-frequency HC function. PMID:19474314

  3. Effects of restricted basilar papillar lesions and hair cell regeneration on auditory forebrain frequency organization in adult European starlings.

    Science.gov (United States)

    Irvine, Dexter R F; Brown, Mel; Kamke, Marc R; Rubel, Edwin W

    2009-05-27

    The frequency organization of neurons in the forebrain Field L complex (FLC) of adult starlings was investigated to determine the effects of hair cell (HC) destruction in the basal portion of the basilar papilla (BP) and of subsequent HC regeneration. Conventional microelectrode mapping techniques were used in normal starlings and in lesioned starlings either 2 d or 6-10 weeks after aminoglycoside treatment. Histological examination of the BP and recordings of auditory brainstem evoked responses confirmed massive loss of HCs in the basal portion of the BP and hearing losses at frequencies >2 kHz in starlings tested 2 d after aminoglycoside treatment. In these birds, all neurons in the region of the FLC in which characteristic frequencies (CFs) normally increase from 2 to 6 kHz had CF in the range of 2-4 kHz. The significantly elevated thresholds of responses in this region of altered tonotopic organization indicated that they were the residue of prelesion responses and did not reflect CNS plasticity. In the long-term recovery birds, there was histological evidence of substantial HC regeneration. The tonotopic organization of the high-frequency region of the FLC did not differ from that in normal starlings, but the mean threshold at CF in this frequency range was intermediate between the values in the normal and lesioned short-recovery groups. The recovery of normal tonotopicity indicates considerable stability of the topography of neuronal connections in the avian auditory system, but the residual loss of sensitivity suggests deficiencies in high-frequency HC function.

  4. Thrombolysis of the basilar artery: 5-year results from the Saarland stroke registry; Thrombolyse der A. basilaris: Ergebnisse im Saarland ueber einen Zeitraum von 5 Jahren

    Energy Technology Data Exchange (ETDEWEB)

    Grunwald, I.Q.; Struffert, T.; Roth, C.; Papanagiotou, P.; Scheuermann, J.; Voges, M.; Reith, W. [Universitaetsklinikum des Saarlandes Homburg (Germany). Klinik fuer Diagnostische und Interventionelle Neuroradiologie

    2005-05-01

    Acute thrombosis of the basilar artery has a fatal outcome if left untreated. The relatively good prognosis with intra-arterial thrombolysis makes it the therapy of choice for acute basilar thrombosis. In the Saarland stroke registry, we analyzed 47 patients with angiographically proven basilar artery thrombosis within the last 5 years. We observed a better outcome in patients with good income, with recanalization, and a short time between onset of symptoms and start of thrombolysis. The complications, such as intracerebral bleedings, occurred only in the group treated with rt-PA. Intra-arterial thrombolysis with urokinase or rt-PA is a relatively safe therapy, but should be performed in neuroradiological centers. With progressing symptoms the therapeutic window can be stretched up to 12 h, but coma lasting for more than 4 h is related to a bad outcome. (orig.) [German] Der akute Verschluss der A. basilaris fuehrt unbehandelt in der Regel rasch zum Tod. Aufgrund des zumeist fatalen Ausgangs unbehandelter Basilaristhrombosen und der relativ guten Prognose bei Behandlung mit lokaler intraarterieller Thrombolyse wird diese Therapie als das Mittel der Wahl bei akuter Basilaristhrombose angesehen. Anhand des Saarlaendischen Schlaganfallregisters wurden 47 Patienten mit einer nachgewiesenen Basilaristhrombose ueber einen Zeitraum von 5 Jahren in diese Studie eingeschlossen. Es konnte nachgewiesen werden, dass eine kurze Zeit bis zum Therapiebeginn, ein gutes Income sowie eine erfolgreiche Rekanalisation mit einem guten klinischen Outcome korreliert waren. Komplikationen traten ausnahmslos bei einer Lysetherapie mit rt-PA auf. Die intraarterielle Behandlung von Basilarisverschluessen mit Urokinase oder rt-PA sollte an spezialisierten, interventionellangiographisch taetigen Zentren vorgenommen werden. Bei fluktuierendem Beginn kann das Zeitfenster bis zu 12 h betragen, nach einer Komadauer von mehr als 4 h ist in der Regel kein guenstiges Outcome zu erwarten. (orig.)

  5. A case of transient hypothermia after trans-lamina terminalis and third ventricle clipping of an extremely high-position basilar tip aneurysm

    Directory of Open Access Journals (Sweden)

    Toshikazu Hidaka

    2015-03-01

    Full Text Available Reports on the trans-lamina terminalis and trans-third ventricular approach are rare. The risk associated with this approach is unknown. After an unsuccessful endovascular surgery, we performed direct surgical clipping via the third ventricle on a 78-year-old woman presenting with an extremely high-positioned, ruptured basilar tip aneurysm. She experienced transient hypothermia for 5 days, and it was considered that this was due to hypothalamic dysfunction. It is necessary to recognize that there is the potential for hypothermia after surgery via the lamina terminalis and third ventricle, even though the mechanisms of hypothalamic thermoregulation are still unclear.

  6. Congenital absence of the internal carotid artery and the basilar artery with persistent trigeminal artery associated with coarctation of the aorta

    Energy Technology Data Exchange (ETDEWEB)

    Jaeger, H.J.; Mehring, U.M.; Gissler, H.M.; Mathias, K.D. [Dept. of Diagnostic Radiology, Staedtische Kliniken Dortmund (Germany); Dept. of Radiology and MicroTherapy, Univ. of Witten/Herdecke (Germany)

    2000-11-01

    We report a case of congenital absence of the cervical and petrous part of the left internal carotid artery, the middle and proximal part of the basilar artery, and the V4 segment of the left vertebral artery associated with a left persistent trigeminal artery and a coarctation of the aorta. The left cerebral vessels are supplied via the anterior communicating artery and the left persistent trigeminal artery. The coexisting coarctation of the aorta led to a subclavian steal phenomenon. The alteration of the cerebral hemodynamics has to be taken in consideration when performing cerebral angiography and surgical correction in such a case. (orig.)

  7. Multicomponent membranes

    Science.gov (United States)

    Kulprathipanja, Santi; Kulkarni, Sudhir S.; Funk, Edward W.

    1988-01-01

    A multicomponent membrane which may be used for separating various components which are present in a fluid feed mixture comprises a mixture of a plasticizer such as a glycol and an organic polymer cast upon a porous organic polymer support. The membrane may be prepared by casting an emulsion or a solution of the plasticizer and polymer on the porous support, evaporating the solvent and recovering the membrane after curing.

  8. Study on the travelling and anatomical variations of basilar artery via VCTDSA%基底动脉走行和变异的容积CT数字减影血管成像研究

    Institute of Scientific and Technical Information of China (English)

    唐贵超; 陈莉; 吕发金

    2013-01-01

    Objective To investigate the anatomical variations and travelling of basilar artery via volume computed tomography digital subtraction angiography (VCTDSA) and to investigate the relationship between the basilar artery bending and the development of intracranial segment of vertebral artery.Methods A total of 110 normal subjects underwent cerebral and cervical vessel VCTDSA were involved in the present study,and the images of basilar arteries were reconstructed by VR images.The development of vertebral artery,window variation and tortuosity of basilar artery,as well as the diameter and length of basilar artery were measured.The correlation between development of vertebral artery and tortuosity of basilar artery were analyzed.Results (1)In the 110cases,the rate of hypoplastic vertebral artery,tortuosity and window variation of basilar artery were 17.27% (19/110),22.73%(25/110) and 2.73%(3/110),respectively.(2)The average length and diameter of basilar artery were(28.25±3.88)mm and (3.86±0.54)mm,respectively.(3)The tortuosity and window variation of basilar artery showed positive correlation with the development of intracranial segment of vertebral artery(P<0.01,r=0.52).Conclusion VCTDSA could clearly show the anatomy and variability of basilar artery,and its anatomic valuable could act as the reference for the diagnosis of cerebral diseases in clinic.The hypoplasia of intracranial segment of vertebral artery could be correlate with tortuosity of basilar artery.%目的 运用容积CT数字减影血管成像(VCTDSA)研究基底动脉走行和变异,探讨基底动脉迂曲与椎动脉颅内段发育不良之间的关系.方法 观测2010年1月至2011年12月在重庆医科大学附属第一医院行VCTDSA检查、非脑卒中患者且头部或头颈VCTDSA检查未见病变者110例,在容积再现(VR)图像上观察双侧椎动脉颅内段发育情况、基底动脉有无迂曲、是否存在窗型变异,并分别测量基底动脉的长度与管径,同时

  9. Basilar artery hypoplasia and its clinical significance%基底动脉发育不全及其临床意义

    Institute of Scientific and Technical Information of China (English)

    张道培; 张淑玲; 许予明

    2015-01-01

    基底动脉发育不全(basilar artery hypoplasia,BAH)在过去较少受到关注,但检出率的提高使得BAH的临床意义逐渐被认识.BAH与血管危险因素相互作用,可能促发后循环缺血事件的发生,脑诱发电位可作为早期检测这一病理生理学事件的重要手段.深入研究BAH的病理意义,有助于加深对后循环缺血事件发病机制的认识.%Basilar artery hypoplasia (BAH) has been paid less attention to in the past.However,the increased detection rate makes the clinical significance of BAH to be gradually recognized.BAH have interaction with vascular risk factors,and this may promote the occurrence of ischemic events in posterior circulation.Brain evoked potential can be used as an important means for early detection of this pathophysiological events.The depth study of pathological significance of BAH helps to deepen the understanding of the mechanisms of posterior circulation ischemic events.

  10. Y stenting assisted coiling using a new low profile visible intraluminal support device for wide necked basilar tip aneurysms: a technical report.

    Science.gov (United States)

    Conrad, Marcelo D; Brasiliense, Leonardo B C; Richie, Alexa N; Hanel, Ricardo A

    2014-05-01

    Many endovascular techniques have been described in recent years for the management of wide necked aneurysms. The Y stent assisted technique has been generally used for coil embolization of wide necked bifurcation aneurysms. This technique was first described for the treatment of basilar tip aneurysms in combination with several different devices, demonstrating encouraging results. We report the results of the first two cases of wide necked basilar tip aneurysms treated with Y stent assisted coil embolization using a new low profile visible intraluminal stent (LVIS Jr; MicroVention, Tustin, California, USA) delivered through a 0.017 inch microcatheter. We also reviewed the literature comparing other endovascular techniques (coiling alone, stent assisted coiling, and Y stent assisted coiling) for wide necked aneurysms. The LVIS Jr device offers a new option for the treatment of these challenging lesions, with clear advantages over currently available intracranial stents. Larger series and long term results are needed to confirm the applicability and durability of this technique/technology.

  11. Effect of ST36 Acupuncture on Hyperventilation-Induced CO2 Reactivity of the Basilar and Middle Cerebral Arteries and Heart Rate Variability in Normal Subjects

    Directory of Open Access Journals (Sweden)

    Sang-Ho Hyun

    2014-01-01

    Full Text Available This study was conducted to verify the effect of acupuncture on cerebral haemodynamics to provide evidence for the use of acupuncture treatment as a complementary therapy for the high-risk stroke population. The effect of ST36 acupuncture treatment on the hyperventilation-induced CO2 reactivity of the basilar and middle cerebral arteries was studied in 10 healthy male volunteers (mean age, 25.2 ± 1.5 years using a transcranial Doppler sonography with an interval of 1 week between measurements, and a portable ECG monitoring system was used to obtain ECG data simultaneously. The CO2 reactivity of the basilar and middle cerebral arteries increased significantly after ST36 acupuncture treatment, whereas the mean arterial blood pressure and pulse rate did not change significantly. The high-frequency power significantly increased after ST36 acupuncture treatment, and the percentage increase of high-frequency power correlated significantly with the percentage increase in the CO2 reactivity of the contralateral middle cerebral artery. These data suggest that ST36 acupuncture treatment increases CO2 reactivity, indicating improvement of vasodilatory potential of the cerebral vasculature to compensate for fluctuations caused by changes in external conditions. The increase in parasympathetic tone by ST36 acupuncture treatment is responsible for this therapeutic effect.

  12. El cierre de la sincondrosis esfeno-basilar y su influencia en la morfología craneofacial

    Directory of Open Access Journals (Sweden)

    Sardi, Marina Laura

    2008-01-01

    Full Text Available El principal centro de crecimiento de la base craneana durante la ontogenia postnatal es la sincondrosis esfeno-basilar (SEB, que permite la elongación de la línea media en el piso craneano. Su actividad de crecimiento termina entre los 12 a 15 años y su cierre se produce luego de la pubertad. El objetivo de este estudio fue analizar el crecimiento craneofacial entre los 11 y 19 años de edad para determinar si el cierre de la SEB es un evento asociado a cambios en la morfología craneofacial. Se probaron las siguientes hipótesis: a los individuos con la SEB fusionada tienen tamaño significativamente mayor que aquellos que aún tienen la SEB abierta; b la diferenciación de tamaño entre individuos con SEB abierta y fusionada se asocia a cambios en las trayectorias de crecimiento. Se utilizaron 118 cráneos con edad de muerte entre 11 y 19 años. Cada individuo se clasificó según el estado de la SEB (ESEB en: SEBA, aquellos en los que la SEB no está completamente fusionada y SEBF, cuando la superficie exocraneal de la SEB se ha osificado. Se midieron la longitud, ancho y altura de los siguientes componentes craneanos: anteroneural, mesoneural, posteroneural, óptico, respiratorio, masticatorio y alveolar, así como la longitud neural total. Se realizaron análisis de Componentes Principales (ACP y de la Covarianza (ANCOVA, considerando como efectos en la variación al ESEB, la edad y su interacción (ESEB vs edad. Ambos análisis indicaron que hay cambios asociados a la edad. Según ANCOVA, la longitud del componente mesoneural fue la única variable en que hubo diferenciación significativa entre SEBA y SEBF, estando la edad controlada y también fue la única medida, en que la interacción con la edad fue significativa; sin embargo, la diferencia de tamaño es opuesta a lo esperado, mayor en SEBA. Por lo tanto, las hipótesis propuestas se rechazan. La variación se asoció a la edad, pero no a ESEB. Es posible que la actividad osteog

  13. Contribuição ao estudo das malformações occipito-cervical, particularmente da impressão basilar

    Directory of Open Access Journals (Sweden)

    Horacio M. Canelas

    1952-12-01

    Full Text Available The authors outline the development of the spine and skull, particularly of axis, atlas and occipital bone. As neuro-skeletal dysmorphisms, the occipito-cervical malformations belong to the neurodysplastic group. They are classified as skeletal anomalies, associated nervous malformations and meningeal reactions. Vertebralization of the occipital bone and occipitalization of atlas, subluxation of odontoid process, dysplasia of the occipital bone, dystrophia brevicollis and other anomalies are discussed. Special care is given to the study of basilar impression; its concept, history, incidence, clinical and neurological symptoms, radiological characterization (craniographic, perimyelographic and iodoventriculographic aspects and surgical treatment are reviewed. The authors report five cases of occipito-cervical malformations, which are the first references in Brazilian literature. In case 1 the anomalies (manifestation of occipital vertebra and Arnold-Chiari deformity were disclosed at an operation for cisticercosis of the posterior fossa. In the following four cases invagination of the basilar portion of the occipital bone (basilar impression could be radiologically demonstrated; in case 2 a suboccipital craniectomy and a laminectomy of atlas and axis were performed but the patient died a week later and the necroscopic examination confirmed the neuro-skeletal anomalies. In all cases there were several associated malformations. In case 2 there were occipitalization of the atlas, fusion of the first and second cervical vertebrae, supernumerary rib of the seventh cervical vertebra, supernumerary lumbar vertebra, and Arnold-Chiari deformity; at necropsy it was found a syringomyelic cyst on the cervical cord and a fibrous dural ring over the foramen magnum. Case 3 showed the syndrome of Klippel-Feil, besides supernumerary ribs of the seventh cervical and first dorsal vertebrae, Arnold-Chiari malfotmation and probable aplasia of cell groups in the

  14. Wiener kernels of chinchilla auditory-nerve fibers : Verification using responses to tones, clicks, and noise and comparison with basilar-membrane vibrations

    NARCIS (Netherlands)

    Temchin, AN; Recio-Spinoso, A; van Dijk, P; Ruggero, MA

    2005-01-01

    Responses to tones, clicks, and noise were recorded from chinchilla auditory-nerve fibers (ANFs). The responses to noise were analyzed by computing the zeroth-, first-, and second-order Wiener kernels (h(0), h(1), and h(2)). The h(1) s correctly predicted the frequency tuning and phases of responses

  15. The ELANA technique : Constructing a high flow bypass using a non-occlusive anastomosis on the ICA and a conventional anastomosis on the SCA in the treatment of a fusiform giant basilar trunk aneurysm

    NARCIS (Netherlands)

    Streefkerk, HJN; Wolfs, JFC; Sorteberg, W; Sorteberg, AG; Tulleken, CAF

    2004-01-01

    A patient with a partially thrombosed fusiform giant basilar trunk aneurysm presented with devastating headache and symptoms of progressive brain stem compression. Having an aneurysm inaccessible for endovascular treatment, and after failing a vertebral artery balloon occlusion test, he was offered

  16. 翼点入路手术治疗基底动脉顶端动脉瘤%Surgical treatment for basilar artery apex aneurysm via pterional approach

    Institute of Scientific and Technical Information of China (English)

    高成; 刘相轸; 陈会荣; 林成海; 李敬文; 赵振环

    2008-01-01

    目的 回顾分析基底动脉顶端动脉瘤的手术方法和疗效.方法 2002年1月至2006年1月手术治疗基底动脉顶端动脉瘤9例,其中男3例,女6例,年龄29~57岁(平均46.6±8.4岁).按照Hunt-Hess分级,Ⅰ级2例,Ⅱ级5例,Ⅲ级2例.全部患者采用翼点入路手术,术后复查脑血管造影,随访2个月-4年(平均19个月).结果 完全夹闭6例,不全夹闭1例,包裹2例.全部病人存活,按照GOS预后分级,Ⅴ级5例,Ⅳ级3例,Ⅲ级1例.结论 掌握手术技巧,熟悉脚间池的区域显微解剖,对具体病人进行个体化设计,是提高基底动脉顶端动脉瘤手术效果的关键.%Objective To review the method and outcome of surgical treatment for basilar artery apex aneurysms. Method Nine patients who suffered basilar artery apex aneurysms were operated from Jan. 2002 to Jan. 2006. Among these patients, 3 was man and 6 was women. The age is from 29 to 57 years and average is 46.6± 8.4. Two is grade Ⅰ, 5 is grade Ⅱ and 2 is grade Ⅲ according to the Hunt-Hess grading scale system. All patients were treated via pterional approach and post-operational DSA was done to evaluate the effect of operation. The period of follow-up was from 2 months to 4 years. Results None of the patients died of operation. Six aneurysms were clipped completely and 1 was clipped incompletely, and 2 was wrapping. According to the GOS scale, 5 patients were Ⅴ, 3 was Ⅳ and 1 was Ⅲ. Conclusions Surgical treatment is an important method for the therapy of the basilar artery apex aneurysms. Excellent surgical technique and familiarity with microanatomy of interpeduncular cistern is demanded for obtaining a good outcome.

  17. A Clinical Study on the Effect of Yinxing Damo (银杏达莫) Combined with Betahistine Hydrochloride Injection on Vertebral Basilar Artery Ischemic Vertigo

    Institute of Scientific and Technical Information of China (English)

    2005-01-01

    Objective: To evaluate the therapeutic efficacy of Yinxing Damo (银杏达莫, YXDM) combined with Betahistine Hydrochloride Injection (BHI) on vertebra basilar artery ischemic vertigo (VBIV).Methods: Ninety patients with VBIV were randomly divided into two groups; 45 patients (the treated group)were treated with YXDM and BHI intravenous dripping, once a day for 14 days. Another 45 patients (control clinical syndromes and the index of the transcranial Doppler (TCD) and hemorheology were observed. Results: The total effective rate was 100% in the treated group, which was better than that in the control group90.5%, (P<0.05). The indexes of TCD and hemorheology in the treated group were obviously improved after treatment, (P<0.01). Conclusion: YXDM combined with BHT injection had better effect in treating patients with VBIV is an ideal drug for VBIV.

  18. 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...

  19. Longitudinally propagating traveling waves of the mammalian tectorial membrane.

    Science.gov (United States)

    Ghaffari, Roozbeh; Aranyosi, Alexander J; Freeman, Dennis M

    2007-10-16

    Sound-evoked vibrations transmitted into the mammalian cochlea produce traveling waves that provide the mechanical tuning necessary for spectral decomposition of sound. These traveling waves of motion that have been observed to propagate longitudinally along the basilar membrane (BM) ultimately stimulate the mechano-sensory receptors. The tectorial membrane (TM) plays a key role in this process, but its mechanical function remains unclear. Here we show that the TM supports traveling waves that are an intrinsic feature of its visco-elastic structure. Radial forces applied at audio frequencies (2-20 kHz) to isolated TM segments generate longitudinally propagating waves on the TM with velocities similar to those of the BM traveling wave near its best frequency place. We compute the dynamic shear storage modulus and shear viscosity of the TM from the propagation velocity of the waves and show that segments of the TM from the basal turn are stiffer than apical segments are. Analysis of loading effects of hair bundle stiffness, the limbal attachment of the TM, and viscous damping in the subtectorial space suggests that TM traveling waves can occur in vivo. Our results show the presence of a traveling wave mechanism through the TM that can functionally couple a significant longitudinal extent of the cochlea and may interact with the BM wave to greatly enhance cochlear sensitivity and tuning.

  20. Chiari畸形合并颅底凹陷的外科手术治疗%Surgical treatment of Chiari malformation complicated with basilar impression

    Institute of Scientific and Technical Information of China (English)

    马原; 贺伟旗; 程林; 卢敏; 顾建文; 匡永勤; 夏勋; 杨立斌; 张俊海; 程敬民; 杨涛; 黄海东

    2011-01-01

    目的 探讨小骨窗后颅窝减压加枕颈植骨融合内固定术治疗Chiari畸形合并颅底凹陷的手术效果.方法 回顾性分析2006-2010年收治的16例Chiari畸形合并颅底凹陷患者,其中男7例,女9例,年龄17~65岁,平均36.4岁.所有患者均经影像学确诊,手术采取小骨窗后颅窝减压,小脑扁桃体切除,一期取自体髂骨行颈枕植骨融合钢丝内固定,术后行颈托固定3个月.结果 所有患者术后症状均明显改善,无感染或死亡,1例出现引流口脑脊液漏,1例出现一过性肩胛区和胸胁部疼痛,未经治疗自行消失.术后随访6个月,按Symon和Lavender临床标准,治愈6例,好转9例,无效1例.复查MRI显示重建枕大池清晰,无小脑下垂发生,植骨已融合. 结论小骨窗后颅窝减压加枕颈植骨融合钢丝内固定术治疗Chiari畸形合并颅底凹陷效果确切,在增加后颅窝容积同时可减轻脑干腹侧受压,并能重建颅颈交界区稳定性.%Objective To evaluate the therapeutic effect of small craniotomic posterior fossa decompression combined with occipitalcervical bone graft fusion and internal fixation on Chiari malformation complicated with basilar impression. Methods The clinical data of 16 cases (7 males and 9 females, aged 17 to 65 years, mean 36. 4) of Chiari malformation complicated with basilar impression from 2006 to 2010 were retrospectively analyzed. The diagnoses for all the patients were confirmed by radiology. Small craniotomic posterior fossa decompression was performed in all patients, cerebellar tonsils were resected, and then one-stage occipital-cervical bone graft fusion using autogenous iliac bone and internal wiring fixation were performed. Neck support was used for 3 months after surgery. Results Symptoms were significantly improved in all cases after surgical operation. No patient died or infected. Cerebrospinal fluid leakage was found at draining site in one case. Transient pain of scapular and chest was found

  1. 高压氧治疗基底型偏头痛的临床研究%Clinical research on treating basilar migraine with hyperbaric oxygen

    Institute of Scientific and Technical Information of China (English)

    谷松; 过伟峰

    2014-01-01

    Objective:To observe the curative effect and discuss the mechanism of hyperbaric oxygen on treating basilar migraine. Methods: 65 patients with basilar migraine were randomly divided into the treatment group (n=33) and the control group (n=32) by random number table. Patients in the treatment group were treated by sealed pressure cabin, 0.2 MPa(2.0ATA)for 65min, and mask absorbing pure oxygen for 30min×2, absorbing air for 5min and depressurization for 25min, once daily. Patients in the control group were given orally 10mg flunarizine hydrochloride before sleeping. The curative effects were compared for 10 days, a course of treatment. Results:I Before treatment, there was no significant difference in VAS, VRS and non-painful duration between the two groups (P>0.05); After treatment, VAS and VRS reduced obviously in the two groups (P0.05);After treatment, Vs, Vm and Vd increased in both, and it was clearer in the treatment group (P0.05),治疗后两组 VAS、VRS 均较治疗前明显降低(P0.05);治疗后两组BA的Vs、Vm、Vd均有增加,并且治疗组(P<0.01)改善的程度比对照组(P<0.05)明显,治疗组 PI 明显下降;两组治疗后比较,差异具有明显统计学意义(P<0.01)。结论:两组治疗方法均能够显著改善基底型偏头痛患者发作时头痛程度及发作频度,改善患者基底动脉的血流速度及搏动指数,且高压氧治疗优于药物治疗。高压氧治疗基底型偏头痛有效,其机理之一可能为高压氧能够抑制炎性介质及血小板释放,增加基底动脉供血。

  2. Distribuição do contraste em angiografias cerebrais: I - Angiografias carotídeas com enchimento do tronco basilar

    Directory of Open Access Journals (Sweden)

    José Zaclis

    1957-06-01

    Full Text Available A propósito da passagem de contraste, nas angiografias por via carotídea, para vasos não pertencentes ao território de distribuição da artéria na qual o contraste foi injetado, foi feita uma revisão de 700 angiografias. O segmento pós-comunicante da artéria cerebral posterior ipsilateral foi encontrado em 42,5% dos casos; o segmento pós-comunicante da artéria cerebral anterior contralateral apareceu em 49,4%; maior ou menor extensão do segmento pré-comunicante da artéria cerebral anterior do lado oposto foi encontrada em 9,85%; a artéria cerebral média bem como o segmento pré-comunicante da cerebral anterior do lado oposto foram encontrados em 4,85% dos casos. A freqüência da visibilização de outras artérias não pertencentes ao território do vaso no qual o contraste foi injetado pode ser fàcilmente verificada no quadro 1. O motivo principal desta publicação foi dado por um grupo de 22 angiografias, nas quais o contraste, injetado por via carotídea, penetrou também no sistema vértebro-basilar. O fato verificado nestas 22 angiografias cerebrais tem sido relatado raramente. Da discussão do mecanismo pelo qual o contraste penetra no tronco basilar, chegando mesmo, por vêzes, até às artérias vertebrais, resultou uma hipótese segundo a qual o fenômeno seria condicionado por hipotensão arterial, acentuada, mas passageira, produzida por um reflexo hiperativo do seio carotídeo provocado pela própria injeção do contraste. Se fôr comprovada esta hipótese, a demonstração angiográfica de todo o sistema arterial encefálico com uma só injeção de contraste por via carotídea poderá ser viável, deliberadamente, empregando hipotensão induzida e controlada.

  3. Minimally Invasive Treatment of Biventricular Hydrocephalus Caused by a Giant Basilar Apex Aneurysm via a Staged Combination of Endoscopy and Endovascular Embolization: A Case Report.

    Science.gov (United States)

    Setty, Pradeep; Volkov, Andrey; Richards, Boyd; Barrett, Ryan

    2015-01-01

    Biventricular hydrocephalus caused by a Giant Basilar Apex Aneurysm (GBAA) is a rare finding that presents unique and challenging treatment decisions. We report a case of GBAA causing a life-threatening biventricular hydrocephalus in which both the aneurysm and hydrocephalus were given definitive treatment through a staged, minimally invasive approach. An obtunded 82-year-old male was found to have biventricular hydrocephalus caused by an unruptured GBAA obstructing the foramina of Monro. The patient was treated via staged, minimally invasive technique that first involved endoscopic fenestration of the septum pellucidum to create communication between the lateral ventricles. A programmable ventriculo-peritoneal shunt was then placed with a high-pressure setting. The patient was then loaded with dual anti-platelet therapy prior to undergoing endovascular coiling of the GBAA with adjacent stenting of the Posterior Cerebral Artery. He remained on dual anti-platelet therapy and the shunt setting was lowered at the bedside to treat the hydrocephalus. At 6-month follow up, the patient had returned to his cognitive baseline, speaking fluently and appropriately. Biventricular hydrocephalus caused by a GBAA can successfully be treated in a minimally invasive fashion utilizing a combination of endoscopy and endovascular therapy, even when a stent-assisted coiling is needed.

  4. 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.

  5. 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.

  6. 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

  7. 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.

  8. 球囊扩张Apollo支架植入术治疗症状性基底动脉狭窄%Treatment of symptomatic basilar artery stenosis with balloon expandable Apollo stent

    Institute of Scientific and Technical Information of China (English)

    张帆; 蔡玉琴; 郭贵军; 郜利会; 吕彦锋; 徐国栋; 孟庆溪

    2012-01-01

    Objective To observe the safety and effectiveness of balloon expandable Apollo stent for the treatment of symptomatic basilar artery stenosis. Methods Eighteen patients with symptomatic basilar artery stenosis (all >70%) were treated with Apollo stent The mean time of clinical follow-up was 11 months. Clinical evaluation was performed based on the modified Rankin Scale (mRS). Results The stent placement was technically successful in all 18 patients. Clinical symptoms were improved in 16 patients after stenting. The mRS scores of 14 patients after stenting were ≤2, while of 4 patients were >2. Conclusion Balloon expandable Apollo stem placement is a safe and efficacious alternative for the treatment of symptomatic basilar stenosis.%目的 观察球囊扩张支架植入术治疗症状性基底动脉狭窄的疗效及安全性.方法 应用Apollo支架治疗18例症状性基底动脉严重狭窄(>70%)患者,术后平均随访11个月,以改良Rankin量表(mRS)评分为基础评价治疗效果.结果 对所有患者均成功植入支架,16例患者临床症状得到不同程度改善;18例中,14例mRS评分≤2分,4例mRS评分>2分.结论 球囊扩张支架植入术治疗症状性基底动脉狭窄安全、有效.

  9. 都梁软胶囊治疗基底动脉型偏头痛39例%Clinical Therapy Observation of Duliang Soft Capsule for Treating Basilar Artery Migraine in 39 Cases

    Institute of Scientific and Technical Information of China (English)

    陈忠伦; 王欣; 段劲峰

    2012-01-01

    目的 观察都梁软胶囊时基底动脉型偏头痛的治疗效果.方法 将76例患者随机分成治疗组(39例)和对照组(37例),治疗组联合服用都梁软胶囊和尼莫地平,对照组单用尼莫地平,治疗2周,观察疼痛及伴随症状的变化.结果 治疗组比对照组疼痛强度降低更明显(P<0.05),总有效率亦高于对照组(P<0.05).结论联合服用都梁软胶囊治疗基底动脉型偏头痛安全、有效.%Objective To investigate the effect of Duliang Soft Capsule in treating basilar artery migraine. Methods 76 cases of basilar artery migraine were randomly divided into two groups, the treatment group( 39 cases) and the control group( 37 cases ). The treatment group was given Duliang Soft Capsule plus nimodipine, while the control group received nimodipine alone. The change of pain and accompanied symptoms were observed after 2 - week treatment. Results The pain intensity in the treatment group was significantly decreased than the control group( P < 0. 05 ), the total effective rate was also higher than that in the control group( P < 0.05). Conclusion The combination use of Duliang Soft Capsule is safe and effective to treat basilar artery migraine.

  10. 基底动脉狭窄与认知功能改变的临床分析%Relation between basilar artery stenosis and cognitive impairment

    Institute of Scientific and Technical Information of China (English)

    李慧英; 黄一宁; 叶长青; 白静

    2012-01-01

    Objective To study the relation between autoregulation of bilateral posterior cerebral artery flow and cognitive function in patients with basilar artery stenosis. Methods Fifteen patients with basilar artery stenosis were divided into stenosis group without cerebral infaction(n = 9) and stenosis group with cerebral infaction(n = 6). Ten healthy volunteers served as a control group. Autoregulation of bilateral posterior cerebral artery flow was assessed by transcranial Doppler ultrasound breath holding test and oblique test. Executive function,structural skill,auditory, visual and logical memory, information processing speed and visuospatial ability were assayed according to the overall neurophysiolgy test and Montreal cognitive assessment(MCA). Results The information processing speed and visuospatial ability were significantly lower in stenosis group with cerebral infarction than in control group(P<0. 05). The visuospatial ability was significantly higher in stenosis group with cerebral infarction than in stenosis group without cerebral infarction(P<0. 05). The breath holding index of posterior cerebral artery and the proportion of anterior and posterior circulating vascular motion reactivity were significantly lower in stenosis group with cerebral infarction and stenosis group without cerebral infarction than in control group (P<0. 05). The proportion of anterior and posterior circulating vascular motion reactivity was positively related with the visuospatial ability (r=0. 830, P<0. 05). Conclusion Patients with basilar artery stenosis may have cognitive impairment at different severity before cerebral infarction and its hemodynamic change is related with cognitive impairment.%目的 探讨基底动脉狭窄患者双侧大脑后动脉的脑血流自动调节变化与认知功能改变之间的关系.方法 选择基底动脉狭窄患者15例,并根据有无脑梗死分为狭窄无梗死组9例和狭窄梗死组6例,另选健康体检者10例为对照组.应用

  11. Classification and its clinical significance of basilar invagination%颅底凹陷症的分型及其意义

    Institute of Scientific and Technical Information of China (English)

    王建华; 尹庆水; 夏虹; 艾福志; 吴增晖; 马向阳; 章凯

    2011-01-01

    Objective:To investigate the classification of basilar invaglnation so as to provide a criterion for surgery determination. Method:70 cases suffering basilar invagination determined by radiography,CT and MRI from March 2007 to March 2010 in our hospital were divided into two groups (stable group and unstable group) based on present of atlas-occipital or atlas-axis dislocation.The deformities such as occipital-atlas fusion,Chiari malformation,slippage of the axis facets,syringomyelia were recorded.Several parameters including clivus slope,distance from odontoid to Chamberlain line and distance form odontoid to foramen magnum line were measured,and the spine medulla compression and the sursical approach of each group were recorded respectively. Result:20 cases were termed as stable and 50 as unstable. Among the stable group,there were 18 Chiari deformity(90%) and 15 syringomyelia(75%);while among the unstable group,there were 2 Chiari deformity (4%),46 occipital-atalas fusion(92%),37 slippage of upper facets(74%),and 43 syringomyelia( 86% ).And the clivns slope angle was 168°±5° and 133°±11° for stable and unstable group respectively(P<0.05);the distance from odontoid to the Chamberlain line was -4,8±4.2mm and -5.6±3.7mm for stable and unstable group respectively (P>0.05);and the distance form odontoid to the foramen magnum line was 0.5±-0.3mm and -6.9±2.9mm for stable and unstable group respectively (P<0.05).In the stable group,2 cases complicated with ventral medulla compression, 11 with dorsal and 7 cases with both underwent the posterior cranial fossa decompression;while all 50 unstable cases(44 with ventral and 6 with both ventral and dorsal medulla compressions) experienced transoral anterior release and instrumentation. Conclusion:The basilar invagination can be divided into two types based on present of atlas-occipital or atls-axls dislocation,which is used to differentiate the anatomic and clinical characters for both groups and

  12. Impressão basilar e malformação de Arnold-Chiari: considerações técnico-cirúrgicas a propósito de 13 casos

    Directory of Open Access Journals (Sweden)

    José A. Gonçalves da Silva

    1978-03-01

    Full Text Available Os autores empregaram detalhes técnicos pessoais para descompressão da fossa posterior em casos de impressão basilar e/ou maliormação de Arnold-Chiari, consistente em intuoação endotraqueal sem retroflexão da cabeça do paciente, sendo o mesmo operado em posição sentada e com a cabeça ereta. Foi realizada plástica da paquimeninge da fossa posterior com dura-mater de cadáver conservada em glicerina.

  13. The experience for stent assisted therapy application on complicated basilar artery apex aneurysm%支架辅助技术介入治疗复杂基底动脉顶端动脉瘤的临床应用

    Institute of Scientific and Technical Information of China (English)

    张金峰; 张向艳; 左书浩; 王东; 李建华; 屈浙; 田军; 胡昱红

    2015-01-01

    目的:总结采用支架辅助技术结合弹簧圈介入治疗复杂基底动脉顶端动脉瘤中的经验,并评估其安全性。方法回顾分析27例复杂基底动脉顶端动脉瘤,采用支架技术结合弹簧圈栓塞基底动脉顶端动脉瘤的临床资料。结果27例手术完成,影像学示完全填塞19例,近全填塞7例,疏松填塞1例。手术并发症3例:1例出血,1例载瘤动脉闭塞,1例弹簧圈脱落。死亡2例:1例V级,1例术前2次出血。结论支架辅助技术结合弹簧圈介入治疗复杂基底动脉顶端动脉瘤是一种可选择的、安全的、有效的方法。%Objective To evaluate the security of application with stent assisted therapy combined with axiom detach-able coil on complicated basilar artery apex aneurysm. Method To review and analyze 27 complicated basilar artery apex aneurysm surgery cases, using the application of stent assisted therapy combined with detachable coil deal with the basilar artery apex aneurysm. Result The image of the 27 surgery cases showed that 19 cases were completed tamponed, and 7 cased were nearly completed tamponed, 1 loose tamponed. It also had three operation complica-tions:one hemorrhaged, one parent artery occlusion, one coil detached. 2 death cases: one was V-level, another had secondary hemorrhaged before surgery. Conclusion The application with stent assisted therapy on complicated basilar artery apex aneurysm is selectable, safe and effective.

  14. 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.

  15. 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.

  16. 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.

  17. 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.

  18. 补阳还五汤治疗椎基底动脉供血不足所致眩晕34例%Treating 34 cases of vertigo caused by vertebro-basilar artery insufficiency with the Buyanghuanwu decoction

    Institute of Scientific and Technical Information of China (English)

    万继松; 田中旺

    2012-01-01

      Objective: To observe the clinical effect of the Buyang Huanwu decoction in treating vertigo caused by vertebro-basilar artery insufficiency. Methods: The Buyang Huanwu decoction was given once a day modified with different symptoms. There were 20 days in each course of treatment. The clinical effect was observed after 2 courses of treatment. Results: The total effective rate was 91%. Conclusion: The Buyang Huanwu decoction had significant effect in treating vertigo caused by vertebro-basilar artery insufficiency.%  目的:观察补阳还五汤治疗椎基底动脉供血不足所致眩晕的临床疗效。方法:给予补阳还五汤,并随证加味治疗,1剂/d,20d 为1个疗程,2个疗程后观察疗效。结果:总有效率91%。结论:补阳还五汤治疗基底动脉供血不足所致眩晕疗效显著。

  19. 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.

  20. 椎-基底动脉的应用解剖学研究%Applied anatomy research of vertebral basilar artery

    Institute of Scientific and Technical Information of China (English)

    尹金鹏

    2015-01-01

    目的:对椎-基底动脉的应用解剖学进行研究分析,为颈椎手术治疗提供依据。方法选取当地实验中心的15具成人尸体的头部标本进行研究,对标本进行灌注和解剖,观察右侧和左侧椎动脉穿越第六颈椎处外径和椎动脉起始处外径,比较右侧和左侧大脑后动脉与基底动脉、小脑上动脉与基底动脉、小脑下后动脉与椎动脉、小脑下前动脉与基底动脉、锁骨下动脉与椎动脉的夹角,同时对比右侧和左侧大脑后动脉起始处外径、小脑上动脉起始处外径、小脑下前动脉起始处外径、小脑下后动脉起始处外径。结果右侧椎动脉穿越第六颈椎处外径和椎动脉起始处外径均低于左侧椎动脉穿越第六颈椎处外径和椎动脉起始处外径,差异具有统计学意义(P<0.05)。右侧大脑后动脉与基底动脉、小脑上动脉与基底动脉、锁骨下动脉与椎动脉的夹角高于左侧锁骨下动脉与椎动脉的夹角,而右侧小脑下后动脉与椎动脉、小脑下前动脉与基底动脉夹角低于左侧小脑下后动脉与椎动脉、小脑下前动脉与基底动脉夹角,差异具有统计学意义(P<0.05)。右侧小脑下前动脉起始处外径高于左侧小脑下前动脉起始处外径,差异具有统计学意义(P<0.05)。结论椎动脉、椎基底动脉、小脑下前动脉起始处外径左、右两侧起始处的夹角存在一定的差异性,呈现出不对称性,这对颈椎外科手术及血管介入治疗具有重要的指导作用。%Objective To study applied anatomy of vertebral basilar artery and provide basis for cervical spine surgery. Methods choose 15 adult cadavers at local experiment center and study their head specimens by perfusion and anatomy, and o bserve external diameter of part of right and left vertebral artery crossing the 6th cervical vertebra, and starting point of vertebra l artery, and compare intersection angle between

  1. 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.

  2. 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....

  3. 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.

  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. 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.

  6. 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 control...

  7. 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

  8. 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

  9. Posterior decompression and occipitocervical fusion with bone graft in treatment of basilar invagination%后路减压枕颈融合与植骨治疗颅底凹陷症

    Institute of Scientific and Technical Information of China (English)

    王亮; 陈宗雄

    2013-01-01

    Objective To evaluate the efficacy of posterior cervical decompression and occipito-cervical fusion with iliac bone graft and internal fixation for basilar invagination. Methods From January 2010 to March 2012,21 patients( 12 males,9 females )with basilar invagination were given posterior cervical decompression and occipitocervical fusion with iliac bone graft and internal fixation, and all of them received cervical collar fixation for 3 months and rehabilitation exercises. Results The spinal cord in the region of foramen magnum was fully decompressed in all cases according to imaging data after operation. The mean follow-up time was 14 months. The postoperative JOA score was higher than the preoperative one ( 14. 1 points vs. 8. 1 points )with the improvement rate of 67.4% . Conclusion Posterior cervical decompression and occipitocervical fusion with autogenous iliac bone graft and internal fixation is an effective treatment for basilar invagination, which can improve patient's neurological symptoms and the quality of life.%目的 评价颈后路减压后枕颈融合内固定加自体髂骨移植治疗颅底凹陷症的疗效.方法 采用颈后路枕下充分减压+枕颈融合内固定及自体髂骨移植术治疗21例颅底凹陷症患者,术后所有患者给予颈托固定3个月及康复锻炼.结果 本组患者术后影像学检查显示枕骨大孔处脊髓已得到充分减压,平均随访时间14个月,术后JOA评分平均14.1分,明显大于术前的8.1分,改善率为67.4%.结论 颈后路减压后枕颈融合内固定加自体髂骨移植是治疗颅底凹陷症的一种有效方法,可改善患者神经症状,提高生活质量.

  10. 不同结构支架植入蜿蜒型颅内动脉瘤的仿真研究%Simulation of Intervention for Basilar Sinuous Aneurysms with Different Structural Stent

    Institute of Scientific and Technical Information of China (English)

    乔爱科; 顾兆勇; 孟宪龙; 付文宇

    2011-01-01

    Endovascular stents with different stent shapes or wire cross-section shapes have different effects on the hemodynamics of basilar aneurysm. To quantitatively understand the difference, computational fluid dynamics simulation were performed to investigate the hemodynamics of basilar sinuous aneurysms treated with four types of virtual mesh stents with different porosities and different wire cross-section shapes. Results show that the triangle stent with a lower porosity has more superiority than other stents in weakening the impact of blood to the aneurismal wall and decreasing the local high pressure and wall shear stress. The flow resistance of the new stent with a triangle cross-section is different when blood flows in and out of the aneurismal sac, which brings about different hemodynamics in aneurusms after the stent intervention. The stent with a triangle section is more suitable for sinuous basilar aneurysms comparatively. Those results can provide some theoretically guide the structural design of stents.%为了探讨不同结构的血管内支架对颅内复杂动脉瘤的血液动力学特性的影响,针对同一蜿蜒形颅内动脉瘤结构,构建了4种不同的裸支架(截面形状和孔隙率不同),分别植入动脉瘤的有限元模型,进行流体动力学仿真计算,获得了一些血流动力学的定量信息.4种模型中,无论是在减小血流对动脉瘤远端瘤壁冲击,还是在局部高压力的降低以及减小动脉瘤壁面切应力等方面,孔隙率较低的三角形截面的网格支架的效果均优于其他3种模型支架的效果.设计采用的三角形截面支架由于血液流入和流出时的流阻不同,导致该支架植人动脉瘤后对瘤腔血流的影响不同,从而产生了动脉瘤腔内的血流动力学差异.这可以为支架结构设计提供一些理论指导意义.

  11. 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.

  12. Mixed matrix membrane development.

    Science.gov (United States)

    Kulprathipanja, Santi

    2003-03-01

    Two types of mixed matrix membranes were developed by UOP in the late 1980s. The first type includes adsorbent polymers, such as silicalite-cellulose acetate (CA), NaX-CA, and AgX-CA mixed matrix membranes. The silicalite-CA has a CO(2)/H(2) selectivity of 5.15 +/- 2.2. In contrast, the CA membrane has a CO(2)/H(2) selectivity of 0.77 +/- 0.06. The second type of mixed matrix membrane is PEG-silicone rubber. The PEG-silicone rubber mixed matrix membrane has high selectivity for polar gases, such as SO(2), NH(3), and H(2)S.

  13. 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.

  14. Nitrogen monoxide vector of ultrasonic atomizing inhalation improves vertebro-basilar artery insufficiency Hemodynamic changes are detected by transcranial Doppler test

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    BACKGROUND: Latest researches at home and abroad indicate that glycerol trinitrate plays its function because it can metabolize into nitrogen monoxide (NO) in vivo.OBJECTIVE: To study the therapeutic effects of NO vector of ultrasonic atomizing inhalation on vertebro-basilar artery insufficiency (VBI) through transcranial Doppler (TCD) detection and serum NO content and indirect effect of TCD on cerebral blood flow changes.DESIGN: Randomized grouping and controlled clinical study.SETTING: Department of Neurology, the Fourth People's Hospital of Jinan.PARTICIPANTS: A total of 130 patients who were diagnosed as VBI were selected from Department of Neurology, the Fourth People's Hospital of Jinan from December 2001 to December 2005. The involved inpatients were checked by CT and MRI, and met the VBI diagnostic standard enacted by the Fourth National Academic Meeting of Cerebrovascular Disease in 1995. All patients and their relatives provided the confirmed consent. They were randomly divided into low-dose treatment group (n =60), high-lose treatment group (n =30) and control group (n =40).METHODS: Patients in the low-dose and high-dose treatment groups were given ultrasonic atomizing inhalation of 3 mg and 5 mg glycerol trinitrate, respectively, for 20 minutes, once a day. In addition,ligustrazine and energy mixture were used once a day for three days in a course. Cases in the control group were only given ligustrazine and energy mixture. All selected cases accepted TCD, blood NO content was checked at the time of beginning, after the first time and after a period of treatment. According to the TCD test, VBI patients were divided into two groups (high-low flow velocity). The vertebral artery (VA) and basal artery (BA) of left or right sides were detected by 2 Hz detector via occipital window.MAIN OUTCOME MEASURES: ① Blood flow velocity of systolic phase, blood flow velocity of diastole phase and vascular resistance in left and right VA and BA detected by using TCD

  15. 血管内栓塞治疗基底动脉顶端动脉瘤%Endovascular Embolization of Basilar Artery Apex Aneurysms

    Institute of Scientific and Technical Information of China (English)

    阮玉山; 卢桂花; 罗昱; 谭源福; 张超元; 肖绍文

    2011-01-01

    Objective To evaluate the therapeutic effect of endovascular embolization for basilar artery apex aneurysms.Methods A retrospective analysis was performed on 17 patients with posterior circulation aneurysms who underwent endovascular embolization between July 2000 and December 2010. In the patients, 6 cases received the treatment in 2 days after acute bleeding stage, 11 cases were treated at 3 to 10 days post-hemorrhage. Three cases with wide necked intracranial aneurysm received the interventional therapy by self expanding stent (Neuroform) and separable detachable coil. The separable detachable coils were occluded in the aneurysms in 14 cases. Glasgow outcome scale (GOS) was conducted to evaluate the outcomes afterwards. Results Complete embolization ( 100% ) was achieved in 10 cases, 3 aneurysms were 95% embolized, and 3 were 90% embolized. Perforation during embolization occurred in one patient who died in the next day. No re-bleeding case but 2 cases of recurrence were found during a follow-up of 6 -36 months (mean, 15 months) post-embolization. According to GOS, good outcome was achieved in 12 cases, mild disability ( being able to look after themselves in daily life) in 3, and severe disability in 1. Conclusion Endovascular embolization is a minimally invasive, relatively safe and effective method for posterior circulation aneurysms.%目的 评价血管内栓塞治疗基底动脉顶端动脉瘤的疗效.方法 回顾性分析2000年7月~2010年12月血管内栓塞治疗17例基底动脉顶端动脉瘤的临床资料.6例在出血2天内、11例在出血3~10天内进行血管内栓塞治疗.应用Neuroform支架辅助弹簧圈栓塞宽颈动脉瘤3例,弹簧圈栓塞14例.结果 17例中成功栓塞16例,其中10例100%栓塞,3例95%栓塞,3例90%栓塞,术中动脉瘤破裂1例(弹簧罔栓塞,次日死亡).出院时格拉斯哥预后评分(GOS),恢复良好12例;中度病残,但生活能自理3例;重度病残,生活不能自理1例.16例随访6

  16. 基底动脉发育不良与后循环梗死的相关性%Association between basilar artery hypoplasia and posterior circulation infarction

    Institute of Scientific and Technical Information of China (English)

    张志勇; 刘尊敬; 田朝晖; 唐文雄; 刘玮; 薛爽; 焦劲松

    2014-01-01

    其卒中防治工作。%Objective To explore the relationship between basal artery hypoplasia ( BAH ) and posterior circulation ischemic stroke and its clinical characteristics to improve the understanding of BAH. Methods A total of 328 hospitalized patients from April 2012 to April 2014 were enrolled retrospectively. With normal course and regular shape of basilar artery on brain magnetic resonance angiography ( MRA) , other causes of posterior circulation ischemic stroke were excluded.They were divided into BAH ( n=48 ) and non-BAH (n=280) groups according to the morphology and diameter of basilar artery on head MRA. We compared the general information and intracranial vascular variations between two groups, especially the incidence rate of posterior circulation infarction and mean blood flow velocity ( Vm ) of basal artery by analyzing clinical information and MRI findings.Meantime, their clinical outcomes were observed through follow-ups.And detailed clinical features were discussed for the patients with posterior circulation infarction in the BAH group.Results ( 1 ) The concurrent lesions included vertebral artery intracranial segment hypoplasia (n=24, VAH), fetal type posterior artery (n=18, FTPA), persistent trigeminal artery (n=1) and giant fenestration variation on vertebral artery ( n=1 ) in the BAH group.In comparison, it was more liable to cranial vascular variations in the BAH group ( P BAH group ( P<0.05).(3) these cases with stroke in two groups had no mortality during a follow-up period of 4-28 months.There were 3 cases with recurrent posterior circulation stroke in the non-BAH group.The number of cases with mRS scoring 2 points or less in the BAH group was more than that in the non-BAH group at discharge, 30 or 90 days after discharge ( P<0.05 ) .( 4 ) these cases with posterior circulation stroke in the BAH group often presented as lacunar syndrome (9/17), paramedian infarction in pons (9/17) and bilateral VAH plus unilateral FTPA (8/17).Conclusion As a relatively rare disease, BAH

  17. 突发性聋患者椎-基底动脉血流动力学观察%The Vertebral Artery and Basilar Artery Haemodynamics of Sudden Deafness

    Institute of Scientific and Technical Information of China (English)

    邢英姿; 王东海; 侯庆军; 罗宏伟; 梁振

    2014-01-01

    目的:探讨不同频率突发性聋患者的椎-基底动脉血流动力学改变特点。方法以90例突发性聋患者为研究对象,根据听阈曲线类型分为低中频下降组、高频下降组及全频下降组,每组30例,正常对照组30例,各组均行经颅多普勒(transcranial doppler ,TCD)检查,探测双侧椎动脉(vertebral artery ,VA )、基底动脉(basilar artery ,BA),分别记录比较各组收缩期流速(systolic velocity ,Vs)、舒张期流速(diastolic velocity ,Vd)、脉冲指数(pulsitility index ,PI)、阻力指数(resistance index ,RI)。结果①低中频组、高频组、全频组突聋患者椎-基底动脉血流异常率分别为63.33%(19/30)、90.0%(27/30)和90.0%(27/30),对照组异常率为0%,高频及全频组患者血流异常率较低中频组高(P<0.05);高频组患者 VA、BA 以高流速检出较多,全频组患者低流速检出较多(P<0.05)。②突发性聋患者VA、BA的PI、RI与对照组比较差异无统计学意义(P>0.05),高频组VA、BA的Vs、Vd均高于对照组(P<0.05),低中频组BA的Vs高于对照组(P<0.05)。结论突聋患者尤其是高频、全频听力下降者椎-基底动脉血流动力学异常率明显增加。%Objective To explore different characteristics of the vertebral artery and basilar artery haemody-namics in different frequencies to provide a theoretical basis for clinical treatment .Methods 90 cases of sudden deaf-ness were induded and according to hearing curve ,the cases were divided into three groups with 30 cases for each while the control group had 30 subjects .All cases were examined by TCD ,the VA ,BA test .Results Compared with group of median and low frequency sudden deafness ,the abnormal blood flow rate were found with decreased hearing(P0 .05) .High frequency hearing loss compared with the con-trol group patients with sudden deafness

  18. 分期前后方减压治疗合并颅底陷入的Chiari畸形%Treatment of Chiari malformation combined with basilar invagination by staged anterior and posterior decompression

    Institute of Scientific and Technical Information of China (English)

    佟怀宇; 余新光; 张远征; 乔广宇; 王鹏; 尚爱加

    2012-01-01

    Objective There is usually anterior compression of the brain stem in Chiari malformation patients combined with basilar invagination.After anterior decompression,many patients will present elevation of the cerebellar tonsil and resolution of syringomyelia.However,still in some patients,the Chiari malformation and syringomyelia remain unchanged after anterior decompression.This article is to discuss a staged anterior and posterior decompression strategy for the treatment of these patients.Methods 9 cases of Chiari malformation combined with basilar invagination were operated by transoral transpharyngeal odontoidectomy first,observed for 1 -2 months,the Chiari malformation and syringomyelia did not relieve,then posterior foramen magnum decompression,tonsillectomy and expansion of posterior fossa dura combined with occipito - cervical fusion or C1-2 fusion were performed.The patients were followed up for 24 - 60 months ( mean 32 months).Results There was no mortality or severe complication.The clinical symptoms were improved in all patients.The Chiari malformation and syringomyelia were relieved in 8 patients,while unchange in 1 case.Conclusions For Chiari malformation patients combine with basilar invagination,anterior decompression with odontoidectomy should be performed first. In many patients,increase ofposterior fossa volume,improved CSF dynamic may be achieved,posterior fusion will be enough.While in some other patients,only symptoms of basilar invagination may be improved after anterior decompression.So posterior decompression is still important.%目的 合并颅底陷入的Chiari畸形患者常有前方脑干压迫,多数经前路减压即可使扁桃体上移,空洞缩小,但少数患者前路减压后Chiari畸形和脊髓空洞并不减轻,本文旨在探讨采用分期前后方减压治疗该类患者.方法 9例患者经口咽入路齿状突磨除,观察1-2个月后发现Chiari畸形和脊髓空洞未减轻,遂行后方枕大孔减压,小脑扁桃体切

  19. 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.

  20. 黄豆苷元联合倍他司汀治疗椎-基底动脉供血不足96例%Treating 96 cases of vertebro-basilar artery insufficiency with Daidzein and Betahistine

    Institute of Scientific and Technical Information of China (English)

    赵亚恒; 阴伟利; 钱仁义

    2015-01-01

    目的:观察黄豆苷元联合倍他司汀治疗椎-基底动脉供血不足的临床疗效。方法:将96例椎-基底动脉供血不足患者随机分成治疗组和对照组,治疗组应用黄豆苷元联合倍他司汀片,对照组应用倍他司汀片。结果:治疗组总有效率为87.5%,对照组总有效率为79.17%,差异有统计学意义(P<0.0l)。结论:黄豆苷元联合倍他司汀片组的疗效高于倍他司汀片组,故黄豆苷元联合倍他司汀是治疗老年人椎-基底动脉供血不足型眩晕的有效方法。%Objective:To observe clinical efficacy of Daidzein and Betahistine on vertebro-basilar artery insufficiency. Methods:96 cases were randomly divided into the treatment group and the control group. The treatment group took Daidzein and Betahistine; the control group took Betahistine. Results: The total efficiency was 87.5%in the treatment group and 79.1%in the control group. P<0.01. Conclusion:Treating vertebro-basilar artery insufficiency with Daidzein and Betahistine could receive better efficacy.

  1. 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...

  2. 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.

  3. 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.

  4. 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.

  5. 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.

  6. 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.

  7. 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.

  8. 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.

  9. Basilar artery hemodynamics quantitative analysis of the patients with vertigo by 3.0 T MR%眩晕患者基底动脉血流动力学3.0T磁共振研究

    Institute of Scientific and Technical Information of China (English)

    宋利宏; 李晖; 刘怀军

    2013-01-01

    Objective To investigate the hemodynamics of basilar artery and its blood-supply area in patients with vertigo by 3.0 T MR.Methods Fifty patients with vertigo were selected as case group and 50 healthy volunteers were selected as control group.All subjects in the case group and in control group were examined by brain magnetic resonance imaging (MRI),magnetic resonance angiography(MRA),fast cine phase contrast(Fast CINE PC) and flow-sensitive alternating inversion recovery sequence (FAIR).After image postprocessing,the velocity and the blood flow volume of basilar artery were measured and calculated.The FAIR value of bilateral occipital lobe,cerebellum,pons and medulla oblongata was measured.Statistical testing was performed.Results The average velocity,peak velocity and blood flow volume of the basilar artery in case group were significantly lower than those in the control group(the average velocity:(22.47 ±9.14) cm/s vs (31.41 ±5.97) cm/s,t =-5.79,P < 0.0001 ; peak velocity:(31.60 ± 13.18) cm/s vs (44.00 ± 7.84) cm/s,t =-5.71,P <0.0001 ;blood flow volume:(91.14 ±43.92) ml/min vs (127.49 ± 28.33) ml/min,t =-4.92,P <0.0001).The perfusion of the posterior circulation in the case group was lower than that in the control group ((882.35 ±35.22) vs (906.34 ±36.82),t =-3.33,P =0.0012).The average velocity,peak velocity and blood flow volume of the basilar artery in case group whose brain parenchyma and blood vessels were normal were (26.31 ±5.16) cm/s,(36.33 ±6.60) cm/s,(95.38 ±28.16) ml/min respectively,which were all less than those in the control group (average velocity:t =-2.72,P =0.0086 ; peak velocity:t =-3.12,P =0.0027 ;blood flow volume:t =-3.53,P =0.0008).The perfusion of the basilar artery blood-supply area in case group whose brain parenchyma and blood vessels were normal was (904.00 ± 35.82),there was no difference when compared with the control group (906.00 ± 36.82,t =-0.20,P =0.8427).Conclusion Whether the brain parenchyma and blood

  10. Membrane accessibility of glutathione

    DEFF Research Database (Denmark)

    Garcia, Alvaro; Eljack, Nasma D; Sani, Marc-Antoine;

    2015-01-01

    that this cysteine is in a transmembrane domain of the protein. Here we have analysed via fluorescence and NMR spectroscopy as well as molecular dynamics simulations whether glutathione is able to penetrate into the interior of a lipid membrane. No evidence for any penetration of glutathione into the membrane...

  11. 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

  12. 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

  13. 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...

  14. Ion-conducting membranes

    Energy Technology Data Exchange (ETDEWEB)

    Masel, Richard I.; Chen, Qingmei; Liu, Zengcai; Kutz, Robert

    2017-02-28

    An ion conducting polymeric composition mixture comprises a copolymer of styrene and vinylbenzyl-R.sub.s. R.sub.s is selected from the group consisting of imidazoliums, pyridiniums, pyrazoliums, pyrrolidiniums, pyrroliums, pyrimidiums, piperidiniums, indoliums, and triaziniums. The composition contains 10%-90% by weight of vinylbenzyl-R.sub.s. The composition can further comprise a polyolefin comprising substituted polyolefins, a polymer comprising cyclic amine groups, a polymer comprising at least one of a phenylene group and a phenyl group, a polyamide, and/or the reaction product of a constituent having two carbon-carbon double bonds. The composition can be in the form of a membrane. In a preferred embodiment, the membrane is a Helper Membrane that increases the faradaic efficiency of an electrochemical cell into which the membrane is incorporated, and also allows product formation at lower voltages than in cells without the Helper Membrane.

  15. Membrane projection lithography

    Energy Technology Data Exchange (ETDEWEB)

    Burckel, David Bruce; Davids, Paul S; Resnick, Paul J; Draper, Bruce L

    2015-03-17

    The various technologies presented herein relate to a three dimensional manufacturing technique for application with semiconductor technologies. A membrane layer can be formed over a cavity. An opening can be formed in the membrane such that the membrane can act as a mask layer to the underlying wall surfaces and bottom surface of the cavity. A beam to facilitate an operation comprising any of implantation, etching or deposition can be directed through the opening onto the underlying surface, with the opening acting as a mask to control the area of the underlying surfaces on which any of implantation occurs, material is removed, and/or material is deposited. The membrane can be removed, a new membrane placed over the cavity and a new opening formed to facilitate another implantation, etching, or deposition operation. By changing the direction of the beam different wall/bottom surfaces can be utilized to form a plurality of structures.

  16. Ion-conducting membranes

    Energy Technology Data Exchange (ETDEWEB)

    Masel, Richard L.; Chen, Qingmei; Liu, Zengcai; Kutz, Robert

    2016-06-21

    An ion conducting polymeric composition mixture comprises a copolymer of styrene and vinylbenzyl-R.sub.s. R.sub.s is selected from the group consisting of imidazoliums and pyridiniums. The composition contains 10%-90% by weight of vinylbenzyl-R.sub.s. The composition can further comprise a polyolefin comprising substituted polyolefins, a polymer comprising cyclic amine groups, a polymer comprising at least one of a phenylene group and a phenyl group, a polyamide, and/or the reaction product of a constituent having two carbon-carbon double bonds. The composition can be in the form of a membrane. In a preferred embodiment, the membrane is a Helper Membrane that increases the faradaic efficiency of an electrochemical cell into which the membrane is incorporated, and also allows product formation at lower voltages than in cells without the Helper Membrane.

  17. Ordered ceramic membranes

    Energy Technology Data Exchange (ETDEWEB)

    Anderson, M.A.; Hill, C.G. Jr.; Zeltner, W.A.

    1991-10-01

    Ceramic membranes have been formed from colloidal sols coated on porous clay supports. These supported membranes have been characterized in terms of their permeabilities and permselectivities to various aqueous test solutions. The thermal stabilities and pore structures of these membranes have been characterized by preparing unsupported membranes of the correpsonding material and performing N{sub 2} adsorption-desorption and X-ray diffraction studies on these membranes. To date, membranes have been prepared from a variety of oxides, including TiO{sub 2}, SiO{sub 2}, ZrO{sub 2}, and Al{sub 2}O{sub 3}, as well as Zr-, Fe-, and Nb-doped TiO{sub 2}. In many of these membranes pore diameters are less than 2 nm, while in others the pore diameters are between 3 and 5 nm. Procedures for fabricating porous clay supports with reproducible permeabilities for pure water are also discussed. 30 refs., 59 figs., 22 tabs.

  18. Extracorporeal membrane oxygenation circuitry.

    Science.gov (United States)

    Lequier, Laurance; Horton, Stephen B; McMullan, D Michael; Bartlett, Robert H

    2013-06-01

    The extracorporeal membrane oxygenation circuit is made of a number of components that have been customized to provide adequate tissue oxygen delivery in patients with severe cardiac and/or respiratory failure for a prolonged period of time (days to weeks). A standard extracorporeal membrane oxygenation circuit consists of a mechanical blood pump, gas-exchange device, and a heat exchanger all connected together with circuit tubing. Extracorporeal membrane oxygenation circuits can vary from simple to complex and may include a variety of blood flow and pressure monitors, continuous oxyhemoglobin saturation monitors, circuit access sites, and a bridge connecting the venous access and arterial infusion limbs of the circuit. Significant technical advancements have been made in the equipment available for short- and long-term extracorporeal membrane oxygenation applications. Contemporary extracorporeal membrane oxygenation circuits have greater biocompatibility and allow for more prolonged cardiopulmonary support time while minimizing the procedure-related complications of bleeding, thrombosis, and other physiologic derangements, which were so common with the early application of extracorporeal membrane oxygenation. Modern era extracorporeal membrane oxygenation circuitry and components are simpler, safer, more compact, and can be used across a wide variety of patient sizes from neonates to adults.

  19. Efficacy analysis of alprostadil combined with betahistine in treating vertebral-basilar artery insufficiency%前列地尔联合倍他司汀治疗椎-基底动脉供血不足的疗效分析

    Institute of Scientific and Technical Information of China (English)

    肖有为; 许彩芹; 庞燕; 刘宇鹏

    2011-01-01

    目的 观察前列地尔联合倍他司汀治疗椎-基底动脉供血不足的临床疗效.方法 将136例椎-基底动脉供血不足患者随机分为前列地尔联合倍他司汀治疗组(68例)和倍他司汀对照组(68例),观察临床疗效及治疗前后椎-基底动脉平均血流速度的改善情况.结果 治疗组治愈率及总有效率高于对照组(P<0.05);治疗组各动脉平均血流速度均明显较对照组改善(P<0.05).结论 前列地尔联合倍他司汀治疗椎-基底动脉供血不足疗效显著.%Objective To observe the clinical efficacy of alprostadil combined with betahistine in treating vertebral-basilar artery insufficiency.Methods 136 patients with vertebral-basilar artery insufficiency were randomly divided into alprostadil combined with betahistine treatment group (68 cases) and betahistine control group (68 cases), clinical efficacy and the improvement of vertebral-basilar artery mean blood flow rate was observed before and after treatment.Results The cure rate and total effective rate of treatment group were higher ( P < 0.05 ); Artery mean blood flow velocity of treatment group were improved significantly than that in control group ( P < 0.05 ).Conclusion It is effective to treat the vertebral-basilar artery insufficiency with alprostadil combined with betahistine.

  20. CENTRIFUGAL MEMBRANE FILTRATION

    Energy Technology Data Exchange (ETDEWEB)

    Daniel J. Stepan; Bradley G. Stevens; Melanie D. Hetland

    1999-10-01

    The overall project consists of several integrated research phases related to the applicability, continued development, demonstration, and commercialization of the SpinTek centrifugal membrane filtration process. Work performed during this reporting period consisted of Phase 2 evaluation of the SpinTek centrifugal membrane filtration technology and Phase 3, Technology Partnering. During Phase 1 testing conducted at the EERC using the SpinTek ST-IIL unit operating on a surrogate tank waste, a solids cake developed on the membrane surface. The solids cake was observed where linear membrane velocities were less than 17.5 ft/s and reduced the unobstructed membrane surface area up to 25%, reducing overall filtration performance. The primary goal of the Phase 2 research effort was to enhance filtration performance through the development and testing of alternative turbulence promoter designs. The turbulence promoters were designed to generate a shear force across the entire membrane surface sufficient to maintain a self-cleaning membrane capability and improve filtration efficiency and long-term performance. Specific Phase 2 research activities included the following: System modifications to accommodate an 11-in.-diameter, two-disk rotating membrane assembly; Development and fabrication of alternative turbulence promoter designs; Testing and evaluation of the existing and alternative turbulence promoters under selected operating conditions using a statistically designed test matrix; and Data reduction and analysis; The objective of Phase 3 research was to demonstrate the effectiveness of SpinTek's centrifugal membrane filtration as a pretreatment to remove suspended solids from a liquid waste upstream of 3M's WWL cartridge technology for the selective removal of technetium (Tc).

  1. Nanoengineered membrane electrode assembly interface

    Science.gov (United States)

    Song, Yujiang; Shelnutt, John A

    2013-08-06

    A membrane electrode structure suitable for use in a membrane electrode assembly (MEA) that comprises membrane-affixed metal nanoparticles whose formation is controlled by a photochemical process that controls deposition of the metal nanoparticles using a photocatalyst integrated with a polymer electrolyte membrane, such as an ionomer membrane. Impregnation of the polymer membrane with the photocatalyst prior to metal deposition greatly reduces the required amount of metal precursor in the deposition reaction solution by restricting metal reduction substantially to the formation of metal nanoparticles affixed on or near the surface of the polymer membrane with minimal formation of metallic particles not directly associated with the membrane.

  2. Electrochemically switchable polypyrrole coated membranes

    Energy Technology Data Exchange (ETDEWEB)

    Weidlich, Claudia, E-mail: weidlich@dechema.d [DECHEMA e.V., Karl-Winnacker-Institut, Theodor-Heuss-Allee 25, D-60486 Frankfurt am Main (Germany); Mangold, Klaus-Michael [DECHEMA e.V., Karl-Winnacker-Institut, Theodor-Heuss-Allee 25, D-60486 Frankfurt am Main (Germany)

    2011-04-01

    A method for coating membranes with polypyrrole (PPy) has been developed. Different membranes, such as microfiltration as well as ion exchanger membranes have been coated with PPy to yield electrical conductivity of the membranes. The coated membranes have been investigated by cyclic voltammetry and scanning electron microscopy and their permeability and permselectivity have been tested. The results show that PPy can be tailored as cation or anion exchanger and its porosity can be controlled to avoid any impairment of the membrane by the polymer layer. These PPy coated membranes can be applied as electrochemically switchable, functionalised membranes with controllabel and variable separation properties.

  3. Membranes and Fluorescence microscopy

    DEFF Research Database (Denmark)

    Bagatolli, Luis

    2009-01-01

    be provided by microscopy-related techniques. In this chapter, I will attempt to summarize representative examples concerning how microscopy (which provides information on membrane lateral organization by direct visualization) and spectroscopy techniques (which provides information about molecular interaction...

  4. Synthesis of zeolite membranes

    Institute of Scientific and Technical Information of China (English)

    JIANG Haiyang; ZHANG Baoquan; Y. S. Lin; LI Yongdan

    2004-01-01

    Zeolite membranes offer great application potentials in membrane separation and/or reaction due to their excellent separation performance and catalytic ability. Up to present, various synthesis methods of zeolite membranes have been developed, including embedded method,in-situ hydrothermal synthesis method, and secondary growth method etc. Compared with the in-situ hydrothermal synthesis method, the secondary growth method possesses a variety of advantages such as easier operation, higher controllability in crystal orientation, microstructure and film thickness, leading to much better reproducibility. This review provides a concise summary and analysis of various synthesis methods reported in the literature. In particular, the secondary growth method was discussed in detail in terms of crystal orientation, defects and crystal grain layers. Some critical issues were also highlighted, which were conducive to the improvement in the synthesis technology of zeolite membranes.

  5. Hydrogen transport membranes

    Science.gov (United States)

    Mundschau, Michael V.

    2005-05-31

    Composite hydrogen transport membranes, which are used for extraction of hydrogen from gas mixtures are provided. Methods are described for supporting metals and metal alloys which have high hydrogen permeability, but which are either too thin to be self supporting, too weak to resist differential pressures across the membrane, or which become embrittled by hydrogen. Support materials are chosen to be lattice matched to the metals and metal alloys. Preferred metals with high permeability for hydrogen include vanadium, niobium, tantalum, zirconium, palladium, and alloys thereof. Hydrogen-permeable membranes include those in which the pores of a porous support matrix are blocked by hydrogen-permeable metals and metal alloys, those in which the pores of a porous metal matrix are blocked with materials which make the membrane impervious to gases other than hydrogen, and cermets fabricated by sintering powders of metals with powders of lattice-matched ceramic.

  6. Clinical Features,Treatment and Prognosis of Top of the Basilar Artery Syndrome%基底动脉尖综合征的临床表现、治疗及预后分析

    Institute of Scientific and Technical Information of China (English)

    许名远; 查达珍; 郑叶祥; 郑志雄; 李脚跟

    2015-01-01

    目的:总结基底动脉尖综合征( TOBS)的临床表现、治疗及预后。方法回顾性分析2009年6月—2014年3月在福建医科大学附属闽东医院住院治疗的15例TOBS患者的临床资料,总结其临床表现、治疗及预后。结果 TOBS患者以中老年男性多见,临床主要表现为不同程度的意识障碍、眼球运动障碍、瞳孔改变,CT或MRI可以发现基底动脉顶端血管供血区双侧两处以上梗死灶,以丘脑、中脑多见。患者均行机械取栓、溶栓、抗凝等治疗,预后较好。结论 TOBS临床表现形式多样,病死率较高,早期诊断和及时治疗可明显改善患者预后。%Objective To summarize the clinical features, treatment and prognosis of top of the basilar artery syndrome( TOBS). Methods A total of 15 patients with TOBS were selected in Mindong Hospital Affiliated to Fujian Medical University from June 2009 to March 2014,and their clinical data was retrospectively analyzed,the clinical features,treatment and prognosis of TOBS summarized. Results Middle-aged and aged male was main crowd,the main clinical features included varying degrees of conscious disturbance,eyeball movement disorder and pupil changes. CT or MRI showed over 2 infarct lesions of both sides of top of the basilar artery,commonly in thalamus and midbrain. All of the patients were treated with mechanical thrombus extraction,thrombolysis and anticoagulation therapy,and the prognosis was good. Conclusion The clinical features of TOBS was various, and the case fatality rate was high, early diagnosis and timely treatment can effectively improve the prognosis.

  7. The MRI and clinical research in 20 cases with top of the basilar artery syndrome%基底动脉尖综合征20例的MRI与临床研究

    Institute of Scientific and Technical Information of China (English)

    王建军; 陶黎; 赵红; 郑长亮

    2016-01-01

    Objective:To induce the MRI and clinical features in patients with top of the basilar artery syndrome(TOBS).Methods:The clinical and MRI data of the 20 patients with TOBS and the total cerebral angiography data of some patients were analyzed retrospectively,then we summarized their characteristics.Results:The TOBS would grow progressively more debilitating with time. The main clinical manifestations were disturbance of consciousness,abnormal movement of the eyeball, abnormal pupil and hemiplegia.MRI showed the infarction in thalamus,midbrain,bridge,temporal lobe,occipital lobe.4 patients showed vertebral basilar artery with severe stenosis or plaque formation in whole cerebral angiography examination.After treatment,6 cases died,8 cases not recovered and 6 cases improved.Conclusion:The prognosis of TOBS is poor.When there is a sign or imaging changes in 2 or more basal artery lesions,we should take TOBS into account and give timely treatment.%目的:归纳基底动脉尖综合征(TOBS)的MRI及临床特征。方法:回顾性分析20例TOBS患者的临床、MRI资料及部分患者的全脑血管造影资料,并总结其特点。结果:TOBS发病后均呈进行性加重,临床主要表现为意识障碍、眼球运动异常、瞳孔异常、偏瘫;MRI示丘脑、中脑、桥脑、颞叶、枕叶梗死;其中患者行全脑血管造影检查显示椎基底动脉重度狭窄或斑块形成4例。治疗后死亡6例,无恢复8例,好转6例,结论:TOBS预后差,当有基底动脉供血范围内2个以上病灶体征或影像学改变时,应考虑TOBS并及时治疗。

  8. Gel layer formation on membranes in Membrane Bioreactors

    NARCIS (Netherlands)

    Van den Brink, P.F.H.

    2014-01-01

    The widespread application of membrane bioreactors (MBRs) for municipal wastewater treatment is hampered by membrane fouling. Fouling increases energy demand, reduces process performance and creates the need for more frequent (chemical) membrane cleaning or replacement. Membrane fouling in MBRs is k

  9. Impact on floating membranes

    OpenAIRE

    Vandenberghe, Nicolas; Duchemin, Laurent

    2016-01-01

    When impacted by a rigid object, a thin elastic membrane with negligible bending rigidity floating on a liquid pool deforms. Two axisymmetric waves radiating from the impact point propagate. In the first place, a longitudinal wave front -- associated with in-plane deformation of the membrane and traveling at constant speed -- separates an outward stress free domain with a stretched but flat domain. Then, in the stretched domain a dispersive transverse wave travels at a wave speed that depends...

  10. OXYGEN TRANSPORT CERAMIC MEMBRANES

    Energy Technology Data Exchange (ETDEWEB)

    Dr. Sukumar Bandopadhyay; Dr. Nagendra Nagabhushana

    2000-10-01

    This is the third quarterly report on oxygen Transport Ceramic Membranes. In the following, the report describes the progress made by our university partners in Tasks 1 through 6, experimental apparatus that was designed and built for various tasks of this project, thermodynamic calculations, where applicable and work planned for the future. (Task 1) Design, fabricate and evaluate ceramic to metal seals based on graded ceramic powder/metal braze joints. (Task 2) Evaluate the effect of defect configuration on ceramic membrane conductivity and long term chemical and structural stability. (Task 3) Determine materials mechanical properties under conditions of high temperatures and reactive atmospheres. (Task 4) Evaluate phase stability and thermal expansion of candidate perovskite membranes and develop techniques to support these materials on porous metal structures. (Task 5) Assess the microstructure of membrane materials to evaluate the effects of vacancy-impurity association, defect clusters, and vacancy-dopant association on the membrane performance and stability. (Task 6) Measure kinetics of oxygen uptake and transport in ceramic membrane materials under commercially relevant conditions using isotope labeling techniques.

  11. Criticality in Plasma Membranes

    Science.gov (United States)

    Machta, Benjamin; Papanikolaou, Stefanos; Sethna, James; Veatch, Sarah

    2011-03-01

    We are motivated by recent observations of micron-sized critical fluctuations in the 2d Ising Universality class in plasma membrane vesicles that are isolated from cortical cytoskeleton. We construct a minimal model of the plasma membrane's interaction with intact cytoskeleton which explains why large scale phase separation has not been observed in Vivo. In addition, we use analytical techniques from conformal field theory and numerical simulations to investigate the form of effective forces mediated by the membrane's proximity to criticality. We show that the range of this force is maximized near a critical point and we quantify its usefulness in mediating communication using techniques from information theory. Finally we use theoretical techniques from statistical physics in conjunction with Monte-Carlo simulations to understand how criticality can be used to increase the efficiency of membrane bound receptor mediated signaling. We expect that this sort of analysis will be broadly useful in understanding and quantifying the role of lipid ``rafts'' in a wide variety of membrane bound processes. Generally, we demonstrate that critical fluctuations provide a physical mechanism to organize and spatially segregate membrane components by providing channels for interaction over relatively large distances.

  12. Fabrication of electrospun nanofibrous membranes for membrane distillation application

    KAUST Repository

    Francis, Lijo

    2013-02-01

    Nanofibrous membranes of Matrimid have been successfully fabricated using an electrospinning technique under optimized conditions. Nanofibrous membranes are found to be highly hydrophobic with a high water contact angle of 130°. Field emission scanning electron microscopy and pore size distribution analysis revealed the big pore size structure of electrospun membranes to be greater than 2 μm and the pore size distribution is found to be narrow. Flat sheet Matrimid membranes were fabricated via casting followed by phase inversion. The morphology, pore size distribution, and water contact angle were measured and compared with the electrospun membranes. Both membranes fabricated by electrospinning and phase inversion techniques were tested in a direct contact membrane distillation process. Electrospun membranes showed high water vapor flux of 56 kg/m2-h, which is very high compared to the casted membrane as well as most of the fabricated and commercially available highly hydrophobic membranes. ©2013 Desalination Publications.

  13. Biomimetic membranes and methods of making biomimetic membranes

    Energy Technology Data Exchange (ETDEWEB)

    Rempe, Susan; Brinker, Jeffrey C.; Rogers, David Michael; Jiang, Ying-Bing; Yang, Shaorong

    2016-11-08

    The present disclosure is directed to biomimetic membranes and methods of manufacturing such membranes that include structural features that mimic the structures of cellular membrane channels and produce membrane designs capable of high selectivity and high permeability or adsorptivity. The membrane structure, material and chemistry can be selected to perform liquid separations, gas separation and capture, ion transport and adsorption for a variety of applications.

  14. Fractal reconstruction of rough membrane surface related with membrane fouling in a membrane bioreactor.

    Science.gov (United States)

    Zhang, Meijia; Chen, Jianrong; Ma, Yuanjun; Shen, Liguo; He, Yiming; Lin, Hongjun

    2016-09-01

    In this paper, fractal reconstruction of rough membrane surface with a modified Weierstrass-Mandelbrot (WM) function was conducted. The topography of rough membrane surface was measured by an atomic force microscopy (AFM), and the results showed that the membrane surface was isotropous. Accordingly, the fractal dimension and roughness of membrane surface were calculated by the power spectrum method. The rough membrane surface was reconstructed on the MATLAB platform with the parameter values acquired from raw AFM data. The reconstructed membrane was much similar to the real membrane morphology measured by AFM. The parameters (including average roughness and root mean square (RMS) roughness) associated with membrane morphology for the model and real membrane were calculated, and a good match of roughness parameters between the reconstructed surface and real membrane was found, indicating the feasibility of the new developed method. The reconstructed membrane surface can be potentially used for interaction energy evaluation.

  15. Membrane biology: fission behind BARs.

    Science.gov (United States)

    Haucke, Volker

    2012-06-05

    Membrane bending is accomplished in part by amphipathic helix insertion into the bilayer and the assembly of BAR domain scaffolds preparing the membrane for fission. Two recent studies highlight the roles of amphipathic helices and BAR scaffolds in membrane fission and establish the structural basis of membrane bending by the N-BAR protein endophilin.

  16. Electrical properties of polar membranes

    CERN Document Server

    Mosgaard, Lars D; Heimburg, Thomas

    2014-01-01

    Biological membranes are capacitors that can be charged by applying a field across the membrane. The charges on the capacitor exert a force on the membrane that leads to electrostriction, i.e. a thinning of the membrane. Since the force is quadratic in voltage, negative and positive voltage have an identical influence on the physics of symmetric membranes. However, this is not the case for a membrane with an asymmetry leading to a permanent electric polarization. Positive and negative voltages of identical magnitude lead to different properties. Such an asymmetry can originate from a lipid composition that is different on the two monolayers of the membrane, or from membrane curvature. The latter effect is called 'flexoelectricity'. As a consequence of permanent polarization, the membrane capacitor is discharged at a voltage different from zero. This leads to interesting electrical phenomena such as outward or inward rectification of membrane permeability. Here, we introduce a generalized theoretical framework...

  17. Oxygen Transport Ceramic Membranes

    Energy Technology Data Exchange (ETDEWEB)

    S. Bandopadhyay; T. Nithyanantham; X.-D Zhou; Y-W. Sin; H.U. Anderson; Alan Jacobson; C.A. Mims

    2005-11-01

    The present quarterly report describes some of the investigations on the structural properties of dense OTM bars provided by Praxair and studies on newer composition of Ti doped LSF. In the current research, the electrical conductivity and Seebeck coefficient were measured as a function of temperature in air. Based on these measurements, the charge carrier concentration, net acceptor dopant concentration, activation energy of conduction and mobility were estimated. The studies on the fracture toughness of the LSFT and dual phase membranes at room temperature have been completed and reported previously. The membranes that are exposed to high temperatures at an inert and a reactive atmosphere undergo many structural and chemical changes which affects the mechanical properties. To study the effect of temperature on the membranes when exposed to an inert environment, the membranes (LAFT and Dual phase) were heat treated at 1000 C in air and N{sub 2} atmosphere and hardness and fracture toughness of the membranes were studied after the treatment. The indentation method was used to find the fracture toughness and the effect of the heat treatment on the mechanical properties of the membranes. Further results on the investigation of the origin of the slow kinetics on reduction of ferrites have been obtained. The slow kinetics appears to be related to a non-equilibrium reduction pathway that initially results in the formation of iron particles. At long times, equilibrium can be reestablished with recovery of the perovskite phase. 2-D modeling of oxygen movement has been undertaken in order to fit isotope data. The model will serve to study ''frozen'' profiles in patterned or composite membranes.

  18. Surface glycosylation of polymeric membranes

    Institute of Scientific and Technical Information of China (English)

    DAI ZhengWei; WAN LingShu; XU ZhiKang

    2008-01-01

    Surface glycosylation of polymeric membranes has been inspired by the structure of natural biomembranes. It refers to that glycosyl groups are introduced onto the membrane surface by various strategies, which combine the separation function of the membrane with the biological function of the saccharides in one system. In this review, progress in the surface glycosylation of polymeric membranes is highlighted in two aspects, i.e. the glycosylation methods and the potential applications of the surface-glycosylated membranes.

  19. Parallel artificial liquid membrane extraction

    DEFF Research Database (Denmark)

    Gjelstad, Astrid; Rasmussen, Knut Einar; Parmer, Marthe Petrine

    2013-01-01

    This paper reports development of a new approach towards analytical liquid-liquid-liquid membrane extraction termed parallel artificial liquid membrane extraction. A donor plate and acceptor plate create a sandwich, in which each sample (human plasma) and acceptor solution is separated by an arti...... by an artificial liquid membrane. Parallel artificial liquid membrane extraction is a modification of hollow-fiber liquid-phase microextraction, where the hollow fibers are replaced by flat membranes in a 96-well plate format....

  20. 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 m

  1. Recent advances on polymeric membranes for membrane reactors

    KAUST Repository

    Buonomenna, M. G.

    2012-06-24

    Membrane reactors are generally applied in high temperature reactions (>400 °C). In the field of fine chemical synthesis, however, much milder conditions are generally applicable and polymeric membranes were applied without their damage. The successful use of membranes in membrane reactors is primary the result of two developments concerning: (i) membrane materials and (ii) membrane structures. The selection of a suited material and preparation technique depends on the application the membrane is to be used in. In this chapter a review of up to date literature about polymers and configuration catalyst/ membranes used in some recent polymeric membrane reactors is given. The new emerging concept of polymeric microcapsules as catalytic microreactors has been proposed. © 2012 Bentham Science Publishers. All rights reserved.

  2. Recent Advances in Pd-Based Membranes for Membrane Reactors.

    Science.gov (United States)

    Arratibel Plazaola, Alba; Pacheco Tanaka, David Alfredo; Van Sint Annaland, Martin; Gallucci, Fausto

    2017-01-01

    Palladium-based membranes for hydrogen separation have been studied by several research groups during the last 40 years. Much effort has been dedicated to improving the hydrogen flux of these membranes employing different alloys, supports, deposition/production techniques, etc. High flux and cheap membranes, yet stable at different operating conditions are required for their exploitation at industrial scale. The integration of membranes in multifunctional reactors (membrane reactors) poses additional demands on the membranes as interactions at different levels between the catalyst and the membrane surface can occur. Particularly, when employing the membranes in fluidized bed reactors, the selective layer should be resistant to or protected against erosion. In this review we will also describe a novel kind of membranes, the pore-filled type membranes prepared by Pacheco Tanaka and coworkers that represent a possible solution to integrate thin selective membranes into membrane reactors while protecting the selective layer. This work is focused on recent advances on metallic supports, materials used as an intermetallic diffusion layer when metallic supports are used and the most recent advances on Pd-based composite membranes. Particular attention is paid to improvements on sulfur resistance of Pd based membranes, resistance to hydrogen embrittlement and stability at high temperature.

  3. Recent Advances in Pd-Based Membranes for Membrane Reactors

    Directory of Open Access Journals (Sweden)

    Alba Arratibel Plazaola

    2017-01-01

    Full Text Available Palladium-based membranes for hydrogen separation have been studied by several research groups during the last 40 years. Much effort has been dedicated to improving the hydrogen flux of these membranes employing different alloys, supports, deposition/production techniques, etc. High flux and cheap membranes, yet stable at different operating conditions are required for their exploitation at industrial scale. The integration of membranes in multifunctional reactors (membrane reactors poses additional demands on the membranes as interactions at different levels between the catalyst and the membrane surface can occur. Particularly, when employing the membranes in fluidized bed reactors, the selective layer should be resistant to or protected against erosion. In this review we will also describe a novel kind of membranes, the pore-filled type membranes prepared by Pacheco Tanaka and coworkers that represent a possible solution to integrate thin selective membranes into membrane reactors while protecting the selective layer. This work is focused on recent advances on metallic supports, materials used as an intermetallic diffusion layer when metallic supports are used and the most recent advances on Pd-based composite membranes. Particular attention is paid to improvements on sulfur resistance of Pd based membranes, resistance to hydrogen embrittlement and stability at high temperature.

  4. Impact on floating membranes

    CERN Document Server

    Vandenberghe, Nicolas

    2016-01-01

    When impacted by a rigid object, a thin elastic membrane with negligible bending rigidity floating on a liquid pool deforms. Two axisymmetric waves radiating from the impact point propagate. In the first place, a longitudinal wave front -- associated with in-plane deformation of the membrane and traveling at constant speed -- separates an outward stress free domain with a stretched but flat domain. Then, in the stretched domain a dispersive transverse wave travels at a wave speed that depends on the local stretching rate. We study the dynamics of this fluid-body system and we show that the wave dynamics is similar to the capillary waves that propagate at a liquid-gas interface but with a surface tension coefficient that depends on impact speed. We emphasize the role of the stretching in the membrane in the wave dynamics but also in the development of a buckling instability that give rise to radial wrinkles.

  5. [Amniotic membrane in conjunctivoplasty].

    Science.gov (United States)

    Samoila, O; Lacramioara, Totu; Mihu, D

    2012-01-01

    The basic principles of conjunctival reconstruction are similar in all pathologies that inflict conjunctival tissue loss. Large conjunctival defects are difficult to treat, with little conjunctival reserve that can be used to close the defect. The study had the objective to find alternatives to conjunctival autograft. Frozen amniotic membrane was investigated. From 27 cases, 22 cases were reconstructed using amniotic membrane alone, but in 5 cases conjunctival autograft was also needed. Bulbar conjunctiva was reconstructed in 23 cases, of which 19 with pterygium, 3 with conjunctival tumors, one operatory plague. Fornix reconstruction was carried out in 4 cases, one tumor and 3 symblepharons (2 after conjunctival burns and one pemfigus). The rate of pterygium recurrence was 7,14%. Amniotic membrane can heal large defects of the conjunctiva, either bulbar or forniceal.

  6. Effect of membrane curvature on lateral distribution of membrane proteins

    DEFF Research Database (Denmark)

    Bendix, Pól Martin

    2015-01-01

    Several membrane proteins exhibit interesting shapes that increases their preference for certain membrane curvatures. Both peripheral and transmembrane proteins are tested with respect to their affinity for a spectrum of high membrane curvatures. We generate high membrane curvatures by pulling...... membrane tubes out of Giant Unilamellar lipid Vesicles (GUVs). The tube diameter can be tuned by aspirating the GUV into a micropipette for controlling the membrane tension. By using fluorescently labled proteins we have shown that sorting of proteins like e.g. FBAR onto tubes is significantly increased...

  7. Hybrid Filter Membrane

    Science.gov (United States)

    Laicer, Castro; Rasimick, Brian; Green, Zachary

    2012-01-01

    Cabin environmental control is an important issue for a successful Moon mission. Due to the unique environment of the Moon, lunar dust control is one of the main problems that significantly diminishes the air quality inside spacecraft cabins. Therefore, this innovation was motivated by NASA s need to minimize the negative health impact that air-suspended lunar dust particles have on astronauts in spacecraft cabins. It is based on fabrication of a hybrid filter comprising nanofiber nonwoven layers coated on porous polymer membranes with uniform cylindrical pores. This design results in a high-efficiency gas particulate filter with low pressure drop and the ability to be easily regenerated to restore filtration performance. A hybrid filter was developed consisting of a porous membrane with uniform, micron-sized, cylindrical pore channels coated with a thin nanofiber layer. Compared to conventional filter media such as a high-efficiency particulate air (HEPA) filter, this filter is designed to provide high particle efficiency, low pressure drop, and the ability to be regenerated. These membranes have well-defined micron-sized pores and can be used independently as air filters with discreet particle size cut-off, or coated with nanofiber layers for filtration of ultrafine nanoscale particles. The filter consists of a thin design intended to facilitate filter regeneration by localized air pulsing. The two main features of this invention are the concept of combining a micro-engineered straight-pore membrane with nanofibers. The micro-engineered straight pore membrane can be prepared with extremely high precision. Because the resulting membrane pores are straight and not tortuous like those found in conventional filters, the pressure drop across the filter is significantly reduced. The nanofiber layer is applied as a very thin coating to enhance filtration efficiency for fine nanoscale particles. Additionally, the thin nanofiber coating is designed to promote capture of

  8. Membrane adsorber for endotoxin removal

    Directory of Open Access Journals (Sweden)

    Karina Moita de Almeida

    Full Text Available ABSTRACT The surface of flat-sheet nylon membranes was modified using bisoxirane as the spacer and polyvinyl alcohol as the coating polymer. The amino acid histidine was explored as a ligand for endotoxins, aiming at its application for endotoxin removal from aqueous solutions. Characterization of the membrane adsorber, analysis of the depyrogenation procedures and the evaluation of endotoxin removal efficiency in static mode are discussed. Ligand density of the membranes was around 7 mg/g dry membrane, allowing removal of up to 65% of the endotoxins. The performance of the membrane adsorber prepared using nylon coated with polyvinyl alcohol and containing histidine as the ligand proved superior to other membrane adsorbers reported in the literature. The lack of endotoxin adsorption on nylon membranes without histidine confirmed that endotoxin removal was due to the presence of the ligand at the membrane surface. Modified membranes were highly stable, exhibiting a lifespan of approximately thirty months.

  9. Graphene Trans-Electrode Membranes

    Science.gov (United States)

    Kuan, Aaron; Bo, Lu; Rollings, Ryan; Dressen, Don; Branton, Daniel; Golovchenko, Jene

    2014-03-01

    We report an electrical study of suspended single-layer graphene membranes separating reservoirs of electrolyte solution. Because the opposing reservoirs are separated only by an atomically thin membrane, the trans-conductance (ionic current response to a voltage across the membrane) is extremely sensitive to nanoscale defects in the membrane. This sensitivity allows the precise examination and characterization of intrinsic defects in graphene membranes, as well as engineered defects for devices. We will discuss methods for creating single nanopores or distributed defects in our graphene membranes, with the applications of nanopore DNA sequencing and water desalination in mind.

  10. Composite oxygen transport membrane

    Science.gov (United States)

    Christie, Gervase Maxwell; Lane, Jonathan A.

    2014-08-05

    A method of producing a composite oxygen ion membrane and a composite oxygen ion membrane in which a porous fuel oxidation layer and a dense separation layer and optionally, a porous surface exchange layer are formed on a porous support from mixtures of (Ln.sub.1-xA.sub.x).sub.wCr.sub.1-yB.sub.yO.sub.3-.delta. and a doped zirconia. In the porous fuel oxidation layer and the optional porous surface exchange layer, A is Calcium and in the dense separation layer A is not Calcium and, preferably is Strontium. Preferred materials are (La.sub.0.8Ca.sub.0.2).sub.0.95Cr.sub.0.5Mn.sub.0.5O.sub.3-.delta. for the porous fuel oxidation and optional porous surface exchange layers and (La.sub.0.8Sr.sub.0.2).sub.0.95Cr.sub.0.5Fe.sub.0.5O.sub.3-.delta. for the dense separation layer. The use of such materials allows the membrane to sintered in air and without the use of pore formers to reduce membrane manufacturing costs. The use of materials, as described herein, for forming the porous layers have application for forming any type of porous structure, such as a catalyst support.

  11. 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 ...

  12. Dirac membrane and hadrons

    CERN Document Server

    Trzetrzelewski, Maciej

    2011-01-01

    In c=1 units the product (mass x radius) for the neutron and the proton is about 4.7\\hbar assuming their radii equal to 1fm. We show that the corresponding products for the Dirac neutral and charged membrane coincide and are equal 1.6\\hbar.

  13. Bioelectrochemistry II: Membrane Phenomena,

    Science.gov (United States)

    1984-12-11

    techniques for studying protein-lipid interactions and molecular movements in membranes. He discussed spin labels, fluorescent probes, NMR studies and recent...transduction in chloroplasts . Re reviewed the components and reactions at the two reaction centers In photosynthesis, and carefully correlated the structure...particularly useful for considering biological problems involving charge movement (e.g., ion transport, energy transduction, and electrical excitation

  14. Fusion of biological membranes

    Indian Academy of Sciences (India)

    K Katsov; M Müller; M Schick

    2005-06-01

    The process of membrane fusion has been examined by Monte Carlo simulation, and is found to be very different than the conventional picture. The differences in mechanism lead to several predictions, in particular that fusion is accompanied by transient leakage. This prediction has recently been verified. Self-consistent field theory is applied to examine the free energy barriers in the different scenarios.

  15. Bioelectrochemistry II membrane phenomena

    CERN Document Server

    Blank, M

    1987-01-01

    This book contains the lectures of the second course devoted to bioelectro­ chemistry, held within the framework of the International School of Biophysics. In this course another very large field of bioelectrochemistry, i. e. the field of Membrane Phenomena, was considered, which itself consists of several different, but yet related subfields. Here again, it can be easily stated that it is impossible to give a complete and detailed picture of all membrane phenomena of biological interest in a short course of about one and half week. Therefore the same philosophy, as the one of the first course, was followed, to select a series of lectures at postgraduate level, giving a synthesis of several membrane phenomena chosen among the most'important ones. These lectures should show the large variety of membrane-regulated events occurring in living bodies, and serve as sound interdisciplinary basis to start a special­ ized study of biological phenomena, for which the investigation using the dual approach, physico-che...

  16. Composite oxygen transport membrane

    Energy Technology Data Exchange (ETDEWEB)

    Christie, Gervase Maxwell; Lane, Jonathan A.

    2016-11-15

    A method of producing a composite oxygen ion membrane and a composite oxygen ion membrane in which a porous fuel oxidation layer and a dense separation layer and optionally, a porous surface exchange layer are formed on a porous support from mixtures of (Ln.sub.1-xA.sub.x).sub.wCr.sub.1-yB.sub.yO.sub.3-.delta. and a doped zirconia. In the porous fuel oxidation layer and the optional porous surface exchange layer, A is Calcium and in the dense separation layer A is not Calcium and, preferably is Strontium. Preferred materials are (La.sub.0.8Ca.sub.0.2).sub.0.95Cr.sub.0.5Mn.sub.0.5O.sub.3-.delta. for the porous fuel oxidation and optional porous surface exchange layers and (La.sub.0.8Sr.sub.0.2).sub.0.95Cr.sub.0.5Fe.sub.0.5O.sub.3-.delta. for the dense separation layer. The use of such materials allows the membrane to sintered in air and without the use of pore formers to reduce membrane manufacturing costs. The use of materials, as described herein, for forming the porous layers have application for forming any type of porous structure, such as a catalyst support.

  17. Imaging of membranous dysmenorrhea

    Energy Technology Data Exchange (ETDEWEB)

    Rouanet, J.P.; Daclin, P.Y.; Turpin, F.; Karam, R.; Prayssac-Salanon, A. [Dept. of Radiology, C. M. C. Beausoleil, Montpellier (France); Courtieu, C.R. [Dept. of Gynecology, C. M. C. Beausoleil, Montpellier (France); Maubon, A.J. [Dept. of Radiology, C. M. C. Beausoleil, Montpellier (France); Dept. of Radiology, C. H. U. Dupuytren, Limoges (France)

    2001-06-01

    Membranous dysmenorrhea is an unusual clinical entity. It is characterized by the expulsion of huge fragments of endometrium during the menses, favored by hormonal abnormality or drug intake. This report describes a case with clinical, US, and MRI findings before the expulsion. Differential diagnoses are discussed. (orig.)

  18. Synthetic membranes and membrane processes with counterparts in biological systems

    Science.gov (United States)

    Matson, Stephen L.

    1996-02-01

    Conventional synthetic membranes, fashioned for the most part from rather unremarkable polymeric materials, are essentially passive structures that achieve various industrial and biomedical separations through simple and selective membrane permeation processes. Indeed, simplicity of membrane material, structure, and function has long been perceived as a virtue of membranes relative to other separation processes with which they compete. The passive membrane separation processes -- exemplified by micro- and ultrafiltration, dialysis, reverse osmosis, and gas permeation -- differ from one another primarily in terms of membrane morphology or structure (e.g., porous, gel-type, and nonporous) and the permeant transport mechanism and driving force (e.g., diffusion, convection, and 'solution/diffusion'). The passive membrane separation processes have in common the fact that interaction between permeant and membrane material is typically weak and physicochemical in nature; indeed, it is frequently an objective of membrane materials design to minimize interaction between permeant and membrane polymer, since such strategies can minimize membrane fouling. As a consequence, conventional membrane processes often provide only modest separation factors or permselectivities; that is, they are more useful in performing 'group separations' (i.e., the separation of different classes of material) than they are in fractionating species within a given class. It has long been recognized within the community of membrane technologists that biological membrane structures and their components are extraordinarily sophisticated and powerful as compared to their synthetic counterparts. Moreover, biomembranes and related biological systems have been 'designed' according to a very different paradigm -- one that frequently maximizes and capitalizes on extraordinarily strong and biochemically specific interactions between components of the membrane and species interacting with them. Thus, in recent

  19. Dynamics of multicomponent lipid membranes

    Science.gov (United States)

    Camley, Brian Andrew

    We present theoretical and computational descriptions of the dynamics of multicomponent lipid bilayer membranes. These systems are both model systems for "lipid rafts" in cell membranes and interesting physical examples of quasi-two-dimensional fluids. Our chief tool is a continuum simulation that uses a phase field to track the composition of the membrane, and solves the hydrodynamic equations exactly using the appropriate Green's function (Oseen tensor) for the membrane. We apply this simulation to describe the diffusion of domains in phase-separated membranes, the dynamics of domain flickering, and the process of phase separation in lipid membranes. We then derive an analytical theory to describe domain flickering that is consistent with our simulation results, and use this to analyze experimental measurements of membrane domains. Through this method, we measure the membrane viscosity solely from fluorescence microscopy measurements. We study phase separation in quasi-two-dimensional membranes in depth with both simulations and scaling theory, and classify the different scaling regimes and morphologies, which differ from pure two-dimensional fluids. Our results may explain previous inconsistent measurements of the dynamical scaling exponent for phase separation in membranes. We also extend our theory beyond the simplest model, including the possibility that the membrane will be viscoelastic, as well as considering the inertia of the membrane and the fluid surrounding the membrane.

  20. Selective permeability of PVA membranes. I - Radiation-crosslinked membranes

    Science.gov (United States)

    Katz, M. G.; Wydeven, T., Jr.

    1981-01-01

    The water and salt transport properties of ionizing radiation crosslinked poly(vinyl alcohol) (PVA) membranes were investigated. The studied membranes showed high permeabilities and low selectivities for both water and salt. The results were found to be in accord with a modified solution-diffusion model for transport across the membranes, in which pressure-dependent permeability coefficients are employed.

  1. Selective Permeability of PVA Membranes. I: Radiation-Crosslinked Membranes

    Science.gov (United States)

    Katz, Moshe G.; Wydeven, Theodore, Jr.

    1981-01-01

    The water and salt transport properties of ionizing radiation crosslinked poly(vinyl alcohol) (PVA) membranes were investigated. The studied membranes showed high permeabilities and low selectivities for both water and salt. The results were found to be in accord with a modified solution-diffusion model for transport across the membranes, in which pressure-dependent permeability coefficients are employed.

  2. Influence of membrane properties on fouling in submerged membrane bioreactors

    NARCIS (Netherlands)

    Marel, van der P.; Zwijnenburg, A.; Kemperman, A.; Wessling, M.; Temmink, B.G.; Meer, van der W.

    2010-01-01

    Polymeric flat-sheet membranes with different properties were used in filtration experiments with activated sludge from a pilot-scale MBR to investigate the influence of membrane pore size, surface porosity, pore morphology, and hydrophobicity on membrane fouling. An improved flux-step method was us

  3. Extra-corporeal membrane oxygenation

    Science.gov (United States)

    ... page: //medlineplus.gov/ency/article/007234.htm Extracorporeal membrane oxygenation To use the sharing features on this page, please enable JavaScript. Extracorporeal membrane oxygenation (ECMO) is a treatment that uses a ...

  4. Membrane distillation for milk concentration

    NARCIS (Netherlands)

    Moejes, S.N.; Romero Guzman, Maria; Hanemaaijer, J.H.; Barrera, K.H.; Feenstra, L.; Boxtel, van A.J.B.

    2015-01-01

    Membrane distillation is an emerging technology to concentrate liquid products while producing high quality water as permeate. Application for desalination has been studied extensively the past years, but membrane distillation has also potential to produce concentrated food products like concentrate

  5. Disorders of the erythrocyte membrane

    Directory of Open Access Journals (Sweden)

    Sophia Delicou

    2015-12-01

    Full Text Available Hemolytic anemia due to abnormalities of the erythrocyte membrane comprises an important group of inherited disorders. These include hereditary spherocytosis, hereditary elliptocytosis, hereditary pyropoikilocytosis, and the hereditary stomatocytosis syndromes. The erythrocyte membrane skeleton composed of spectrin, actin, and several other proteins is essential for the maintenance of the erythrocyte shape, reversible deformability, and membrane structural integrity in addition to controlling the lateral mobility of integral membrane proteins. These disorders are characterized by clinical and laboratory heterogeneity and, as evidenced by recent molecular studies, by genetic heterogeneity. Defects in various proteins involved in linking the lipid bilayer to membrane skeleton result in loss in membrane cohesion leading to surface area loss and hereditary spherocytosis while defects in proteins involved in lateral interactions of the spectrin-based skeleton lead to decreased mechanical stability, membrane fragmentation and hereditary elliptocytosis. The disease severity is primarily dependent on the extent of membrane surface area loss. Treatment with splenectomy is curative in most patients.

  6. Membrane Cells for Brine Electrolysis.

    Science.gov (United States)

    Tingle, M.

    1982-01-01

    Membrane cells were developed as alternatives to mercury and diaphragm cells for the electrolysis of brine. Compares the three types of cells, focusing on the advantages and disadvantages of membrane cells. (JN)

  7. Novicidin interactions with phospholipid membranes

    DEFF Research Database (Denmark)

    Balakrishnan, Vijay Shankar

    Antimicrobial peptides target bacterial cell membranes and are considered as potential antibiotics. Their interactions with cell membranes are studied using different approaches. This thesis comprises of the biophysical investigations on the antimicrobial peptide Novicidin, interacting with lipos...

  8. Biological Fuel Cells and Membranes.

    Science.gov (United States)

    Ghassemi, Zahra; Slaughter, Gymama

    2017-01-17

    Biofuel cells have been widely used to generate bioelectricity. Early biofuel cells employ a semi-permeable membrane to separate the anodic and cathodic compartments. The impact of different membrane materials and compositions has also been explored. Some membrane materials are employed strictly as membrane separators, while some have gained significant attention in the immobilization of enzymes or microorganisms within or behind the membrane at the electrode surface. The membrane material affects the transfer rate of the chemical species (e.g., fuel, oxygen molecules, and products) involved in the chemical reaction, which in turn has an impact on the performance of the biofuel cell. For enzymatic biofuel cells, Nafion, modified Nafion, and chitosan membranes have been used widely and continue to hold great promise in the long-term stability of enzymes and microorganisms encapsulated within them. This article provides a review of the most widely used membrane materials in the development of enzymatic and microbial biofuel cells.

  9. Role of basilar artery hypoplasia in patients with pontine penetrating artery infarction%基底动脉发育不全在脑桥穿支动脉梗死患者中的作用研究

    Institute of Scientific and Technical Information of China (English)

    张道培; 许予明; 张洪涛; 张淑玲

    2012-01-01

    目的 探讨基底动脉发育不全(BAH)与脑桥穿支动脉梗死的关系及其临床特点.方法 选择头颅MRI确诊的急性脑梗死患者328例,根据诊断分为BAH组27例和无BAH组301例.其中急性后循环穿支动脉梗死患者79例,通过头颅磁共振血管造影术评估基底动脉直径(BAH定义为直径<2 mm)、椎动脉V4段发育不全(V4AH)及胚胎大脑后动脉(FTP)情况.结果 BAH组后循环梗死、动脉发育不全(单侧V4AH、双侧V4AH、单侧FTP、双侧FTP、双侧V4AH和FTP)比例明显高于无BAH组(P<0.01).79例急性后循环穿支动脉梗死患者中,BAH 24例(30.4%),其中脑桥穿支动脉梗死15例(62.5%),后循环其他部位穿支动脉梗死9例(37.5%).在脑桥穿支动脉梗死患者中,合并BAH的比例明显高于未合并BAH的比例(62.5% vs 12.7%,P<0.01).结论 BAH与脑桥穿支动脉梗死的发生有密切关系,这些患者多合并V4AH和FTP.%Objective To study the relation between basilar artery hypoplasia(BAH) and pontine penetrating artery infarction and the clinical characteristics of BAH patients. Methods Three hundred and twenty-eight patients with acute cerebral infarction established by head MRI were divided into BAH group(n = 27) and non-BAH group(n = 301) according to their diagnosis. Basilar artery diameter (which was defined <2 mm according to BAH) , vertebral artery V4 hypoplasia (V4AH) and fetal type posterior(FTP) artery condition were assessed in 79 patients with acute posterior penetrating artery circulation ischemic stroke according to MRI. Results The proportions of posterior circulation ischemic stroke and the unilateral V4AH,bilateral V4AH,unilateral FTP,bilateral FTP, bilateral V4AH and FTP were significantly higher in BAH group than in non-BAH group(P<0. 01). Of the 79 patients with acute posterior circulation penetrating artery infarction,24(30. 4%)were diagnosed with BAH including 15(62. 5%) with pontine penetrating artery infarction and 9(37. 5

  10. Clinical and imaging manifestations of the top - of - the - basilar artery syndrome%基底动脉尖综合征的临床及影像特点分析

    Institute of Scientific and Technical Information of China (English)

    马世江

    2011-01-01

    Objective Clinical manifestation and imaging abnormalities of the top - of - the -basilar artery syndrome (TOBS) have been summarized. Methods Clinical data of 30 patients with TOBS were reviewed retrospectively. Results Most of the cases were middle or old aged. Cerebral thrombosis and cerebral embolism were the major cause of TOBS. The high risk factors included hypertension, diabetes, heart disease, hypercholesterol, and so on. The clinical manifestation comprised the sudden vertigo or unconsciouseness with the dismovement of the eyeballs and the abnormality of the pupils , as well as the dyskinesia, partial blindness or cortical blindness and dystrophy. Computerized tomography(CT)was insensitive for acute infarction. Diffusion weighted imaging ( DWI) demarcated the lesions of infarction in patients with TOBS. Magnetic resonance angiography(MRA) clearly visualized the vertebral arteries, basilar artery and posterior cerebral rteries. Conclusions Diagnosis of TOBS depends on clinical presentation and imaging changes. Magnetic resonance imaging ( MRl) , especially DWI,is superior to CT in early diagnosis of TOBS. Systemic and comprehensive treatment may improve the survival rate of the TOBS patients.%目的 探讨基底动脉尖综合征(TOBS)的病因、临床表现和影像学表现,加深对这种疾病的认识.方法 回顾性分析38例TOBS患者的原始性资料.结果 TOBS患者以中老年为主,主要病因为脑栓塞及脑血栓形成,高危因素有高血压、糖尿病、心脏病、高血脂等,临床表现多以突然眩晕或意识障碍起病,合并眼球运动障碍及瞳孔异常、运动障碍、偏盲、可伴有行为异常等,CT不能清楚显示TOBS早期梗死病灶,磁共振弥散加权扫描(DWI)能准确显示TOBS梗死病灶部位及数目,磁共振血管成像(MRA)能直接反应椎动脉、基底动脉及大脑后动脉情况.结论 TOBS主要依赖临床及影像学表现综合诊断,磁共振检查对于早期诊断基底动脉

  11. Fundamentals of membrane bioreactors materials, systems and membrane fouling

    CERN Document Server

    Ladewig, Bradley

    2017-01-01

    This book provides a critical, carefully researched, up-to-date summary of membranes for membrane bioreactors. It presents a comprehensive and self-contained outline of the fundamentals of membrane bioreactors, especially their relevance as an advanced water treatment technology. This outline helps to bring the technology to the readers’ attention, and positions the critical topic of membrane fouling as one of the key impediments to its more widescale adoption. The target readership includes researchers and industrial practitioners with an interest in membrane bioreactors.

  12. An Electrochromic Bipolar Membrane Diode.

    Science.gov (United States)

    Malti, Abdellah; Gabrielsson, Erik O; Crispin, Xavier; Berggren, Magnus

    2015-07-01

    Conducting polymers with bipolar membranes (a complementary stack of selective membranes) may be used to rectify current. Integrating a bipolar membrane into a polymer electrochromic display obviates the need for an addressing backplane while increasing the device's bistability. Such devices can be made from solution-processable materials.

  13. Cheap Thin Film Oxygen Membranes

    DEFF Research Database (Denmark)

    2009-01-01

    The present invention provides a membrane, comprising a porous support layer a gas tight electronically and ionically conducting membrane layer and a catalyst layer, characterized in that the electronically and ionically conducting membrane layer is formed from a material having a crystallite str...

  14. 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

  15. 耳针联合倍他司汀治疗椎基底动脉供血不足临床疗效回顾性分析%A retrospective analysis of treating vertebral basilar insufifciency by auricular acupuncture plus Betahistine

    Institute of Scientific and Technical Information of China (English)

    汪建平; 辛庆锋

    2016-01-01

    Objective: To retrospectively analyze clinical effects and safety of auricular acupuncture plus Betahistine on vertebral basilar insufficiency. Methods: 56 cases were randomly divided into 2 groups. The control group was given low molecular dextran; the observed group was treated by auricular acupuncture plus Betahistine. Results: The total efficiency and vertebral-basilar artery hemodynamic improvement in the observed group were both obviously better,P0.05). Conclusion: Auricular acupuncture plus Betahistine on vertebral basilar insufifciency showed a signiifcant effects, with safety, and was worthy of promotion.%目的:回顾性分析耳针联合倍他司汀治疗椎基底动脉供血不足的临床疗效及安全性。方法:回顾分析本院2011年1月-2013年12月收治的56例椎基底动脉供血不足患者,依据纠正眩晕的治疗方法分为两组。对照组给予低分子右旋糖酐,观察组给予耳针联合倍他司汀。结果:观察组在临床疗效、椎基底动脉血液动力学改善等方面均明显优于对照组(P0.05)。结论:耳针联合倍他司汀治疗椎基底动脉供血不足疗效显著且安全可靠,值得临床选择和推广。

  16. Impact of sludge flocs on membrane fouling in membrane bioreactors

    DEFF Research Database (Denmark)

    Christensen, Morten Lykkegaard; Niessen, Wolfgang; Jørgensen, Mads Koustrup

    Membrane bioreactors (MBR) are widely used for wastewater treatment, but membrane fouling reduces membrane performance and thereby increases the cost for membranes and fouling control. Large variation in filtration properties measured as flux decline was observed for the different types of sludges...... and the physico-chemical properties, is an efficient method to reduce membrane fouling in the MBR. High concentration of suspended extracellular substances (EPS) and small particles (up to 10 µm) resulted in pronounced fouling propensity. The membrane fouling resistance was reduced at high concentration...... flocs reduced membrane fouling, and more compact and strong flocs were formed if the concentration of divalent ions were high. Sludge was fractionated by centrifugation providing supernatant with soluble EPS and colloidal particles but without flocs. Filtration test on untreated sludge and supernatant...

  17. Membrane separation of hydrocarbons

    Science.gov (United States)

    Chang, Y. Alice; Kulkarni, Sudhir S.; Funk, Edward W.

    1986-01-01

    Mixtures of heavy oils and light hydrocarbons may be separated by passing the mixture through a polymeric membrane. The membrane which is utilized to effect the separation comprises a polymer which is capable of maintaining its integrity in the presence of hydrocarbon compounds and which has been modified by being subjected to the action of a sulfonating agent. Sulfonating agents which may be employed will include fuming sulfuric acid, chlorosulfonic acid, sulfur trioxide, etc., the surface or bulk modified polymer will contain a degree of sulfonation ranging from about 15 to about 50%. The separation process is effected at temperatures ranging from about ambient to about 100.degree. C. and pressures ranging from about 50 to about 1000 psig.

  18. Oxygen Transport Ceramic Membranes

    Energy Technology Data Exchange (ETDEWEB)

    S. Bandopadhyay; N. Nagabhushana; T. Nithyanantham; X.-D Zhou; Y-W. Sin; H.U. Anderson; Alan Jacobson; C.A. Mims

    2005-02-01

    The present quarterly report describes some of the investigations on the structural properties of dense OTM bars provided by Praxair and studies on newer composition of Ti doped LSF. Thermogravimetric analysis (TGA) was carried out on La{sub 0.2}Sr{sub 0.8}Fe{sub 0.55}Ti{sub 0.45}O{sub 3-{delta}} to investigate oxygen deficiency ({delta}) of the sample. The TGA was performed in a controlled atmosphere using oxygen, argon, carbon monoxide and carbon dioxide with adjustable gas flow rates. In this experiment, the weight loss and gain of La{sub 0.2}Sr{sub 0.8}Fe{sub 0.55}Ti{sub 0.45}O{sub 3-{delta}} was directly measured by TGA. The weight change of the sample was evaluated at between 600 and 1250 C in air or 1000 C as a function of oxygen partial pressure. The oxygen deficiencies calculated from TGA data as a function of oxygen activity and temperature will be estimated and compared with that from neutron diffraction measurement in air. The LSFT and LSFT/CGO membranes were fabricated from the powder obtained from Praxair Specialty Ceramics. The sintered membranes were subjected to microstructure analysis and hardness analysis. The LSFT membrane is composed of fine grains with two kinds of grain morphology. The grain size distribution was characterized using image analysis. In LSFT/CGO membrane a lot of grain pullout was observed from the less dense, porous phase. The hardness of the LSFT and dual phase membranes were studied at various loads. The hardness values obtained from the cross section of the membranes were also compared to that of the values obtained from the surface. An electrochemical cell has been designed and built for measurements of the Seebeck coefficient as a function of temperature and pressure. Measurements on La{sub 0.2}Sr{sub 0.8}Fe{sub 0.55}Ti{sub 0.45}O{sub 3-{delta}} as a function of temperature an oxygen partial pressure are reported. Further analysis of the dilatometry data obtained previously is presented. A series of isotope transients

  19. Membrane Assisted Enzyme Fractionation

    DEFF Research Database (Denmark)

    Yuan, Linfeng

    . In this thesis, separations using crossflow elecro-membrane filtration (EMF) of amino acids, bovine serum albumin (BSA) and industrial enzymes from Novozymes were performed. The main objective of this study was to investigate the technological feasibility of EMF in the application of industrial enzyme...... fractionation, such as removal of a side activity from the main enzyme activity. As a proof-of-concept, amino acids were used as model solution to test the feasibility of EMF in the application of amphoteric molecule separation. A single amino acid was used to illustrate the effect of an electric field...... on the separation performance were very small in the investigated range. The mass transport of each enzyme can be well explained by the Extended-Nernst-Planck equation. Better separation was observed at lower feed concentration, higher solution pH in the investigated range and with a polysulfone (PS) MF membrane...

  20. Electrochemical polymer electrolyte membranes

    CERN Document Server

    Fang, Jianhua; Wilkinson, David P

    2015-01-01

    Electrochemical Polymer Electrolyte Membranes covers PEMs from fundamentals to applications, describing their structure, properties, characterization, synthesis, and use in electrochemical energy storage and solar energy conversion technologies. Featuring chapters authored by leading experts from academia and industry, this authoritative text: Discusses cutting-edge methodologies in PEM material selection and fabricationPoints out important challenges in developing PEMs and recommends mitigation strategies to improve PEM performanceAnalyzes the cur

  1. Membrane Transport Phenomena (MTP)

    Science.gov (United States)

    Mason, Larry W.

    1997-01-01

    The third semi-annual period of the MTP project has been involved with performing experiments using the Membrane Transport Apparatus (MTA), development of analysis techniques for the experiment results, analytical modeling of the osmotic transport phenomena, and completion of a DC-9 microgravity flight to test candidate fluid cell geometries. Preparations were also made for the MTP Science Concept Review (SCR), held on 13 June 1997 at Lockheed Martin Astronautics in Denver. These activities are detailed in the report.

  2. Study of basilar artery hemodynamic changes in cervical rotation and flexion by color Doppler ultrasound%彩色多普勒超声对正常人头颈部分别向左右转动后基底动脉血流的观察

    Institute of Scientific and Technical Information of China (English)

    杨玉杰; 李敬府; 白志勇; 王金锐

    2009-01-01

    Objective To evaluate the basilar artery hemodynamical changes in cervical rotation and ventral flexion by color Doppler flow imaging(CDFI). Methods Basilar artery blood flow were detected during cervical With cervical right lateral,left lateral rotation and ventral flexion, the detection ratio of basilar artery by ultrasound were 89% ,84% ,81% respectively. There were no difference in statistics between the detction ratio of three kinds during cervical flexion,peak systolic velocity(PSV) and end-diastolic velocity(EDV) decreased apparently during left lateral rotation,which did not change during right lateral rotation. No changing was found with resistant index between the three kinds of cervical position. Conclusions The hemodynamic changing of basilar artery during cervical rotation and flexion could be detected by CDFI accurately,which might be useful in clinical study.%目的 应用彩色多普勒超声评价正常人头颈部分别向左右转动后基底动脉(BA)血流动力学参数.方法 应用彩色多普勒超声对62例正常人在俯卧位低头以及头颈部分别向左右转动90°后三种姿势下,观察BA血流,并对其血流动力学指标进行对比分析.结果 ①三种姿势下BA的检出率:俯卧位低头为89%,头颈部左转为84%,头颈部右转为81%,三种姿势下BA血流的显示率比较差异无统计学意义(P>0.05).②椎动脉颁段内径:左侧大于右侧[左侧(0.34±0.06)cm对右侧(0.32±0.05)cm,P0.05),三种姿势下阻力指数差异无统计学意义(P>0.05).结论 彩色多普勒超声对BA检出率高,能够准确清晰地显示不同姿势下BA的血流动力学情况,提示正常人头颈部向左转时对BA血流有影响,对研究椎-基底动脉系血流动力学有着重要的临床意义.

  3. Recycling of used perfluorosulfonic acid membranes

    Science.gov (United States)

    Grot, Stephen; Grot, Walther

    2007-08-14

    A method for recovering and recycling catalyst coated fuel cell membranes includes dissolving the used membranes in water and solvent, heating the dissolved membranes under pressure and separating the components. Active membranes are produced from the recycled materials.

  4. Virus separation using membranes.

    Science.gov (United States)

    Grein, Tanja A; Michalsky, Ronald; Czermak, Peter

    2014-01-01

    Industrial manufacturing of cell culture-derived viruses or virus-like particles for gene therapy or vaccine production are complex multistep processes. In addition to the bioreactor, such processes require a multitude of downstream unit operations for product separation, concentration, or purification. Similarly, before a biopharmaceutical product can enter the market, removal or inactivation of potential viral contamination has to be demonstrated. Given the complexity of biological solutions and the high standards on composition and purity of biopharmaceuticals, downstream processing is the bottleneck in many biotechnological production trains. Membrane-based filtration can be an economically attractive and efficient technology for virus separation. Viral clearance, for instance, of up to seven orders of magnitude has been reported for state of the art polymeric membranes under best conditions.This chapter summarizes the fundamentals of virus ultrafiltration, diafiltration, or purification with adsorptive membranes. In lieu of an impractical universally applicable protocol for virus filtration, application of these principles is demonstrated with two examples. The chapter provides detailed methods for production, concentration, purification, and removal of a rod-shaped baculovirus (Autographa californica M nucleopolyhedrovirus, about 40 × 300 nm in size, a potential vector for gene therapy, and an industrially important protein expression system) or a spherical parvovirus (minute virus of mice, 22-26 nm in size, a model virus for virus clearance validation studies).

  5. Novel Catalytic Membrane Reactors

    Energy Technology Data Exchange (ETDEWEB)

    Stuart Nemser, PhD

    2010-10-01

    There are many industrial catalytic organic reversible reactions with amines or alcohols that have water as one of the products. Many of these reactions are homogeneously catalyzed. In all cases removal of water facilitates the reaction and produces more of the desired chemical product. By shifting the reaction to right we produce more chemical product with little or no additional capital investment. Many of these reactions can also relate to bioprocesses. Given the large number of water-organic compound separations achievable and the ability of the Compact Membrane Systems, Inc. (CMS) perfluoro membranes to withstand these harsh operating conditions, this is an ideal demonstration system for the water-of-reaction removal using a membrane reactor. Enhanced reaction synthesis is consistent with the DOE objective to lower the energy intensity of U.S. industry 25% by 2017 in accord with the Energy Policy Act of 2005 and to improve the United States manufacturing competitiveness. The objective of this program is to develop the platform technology for enhancing homogeneous catalytic chemical syntheses.

  6. Quantum charged rigid membrane

    Energy Technology Data Exchange (ETDEWEB)

    Cordero, Ruben [Departamento de Fisica, Escuela Superior de Fisica y Matematicas del I.P.N., Unidad Adolfo Lopez Mateos, Edificio 9, 07738 Mexico, D.F. (Mexico); Molgado, Alberto [Unidad Academica de Fisica, Universidad Autonoma de Zacatecas, Zacatecas Zac. (Mexico); Rojas, Efrain, E-mail: cordero@esfm.ipn.mx, E-mail: amolgado@fisica.uaz.edu.mx, E-mail: efrojas@uv.mx [Departamento de Fisica, Facultad de Fisica e Inteligencia Artificial, Universidad Veracruzana, 91000 Xalapa, Veracruz (Mexico)

    2011-03-21

    The early Dirac proposal to model the electron as a charged membrane is reviewed. A rigidity term, instead of the natural membrane tension, involving linearly the extrinsic curvature of the worldvolume swept out by the membrane is considered in the action modeling the bubble in the presence of an electromagnetic field. We set up this model as a genuine second-order derivative theory by considering a non-trivial boundary term which plays a relevant part in our formulation. The Lagrangian in question is linear in the bubble acceleration and by means of the Ostrogradski-Hamiltonian approach, we observed that the theory comprises the management of both first- and second-class constraints. We thus show that our second-order approach is robust allowing for a proper quantization. We found an effective quantum potential which permits us to compute bounded states for the system. We comment on the possibility of describing brane world universes by invoking this kind of second-order correction terms.

  7. Quantum charged rigid membrane

    CERN Document Server

    Cordero, Ruben; Rojas, Efrain

    2010-01-01

    The early Dirac proposal to model the electron as a charged membrane is reviewed. A rigidity term, instead of the natural membrane tension, involving linearly the extrinsic curvature of the worldvolume swept out by the membrane is considered in the action modeling the bubble in the presence of an electromagnetic field. We set up this model as a genuine second-order derivative theory by considering a non-trivial boundary term which plays a relevant part in our formulation. The Lagrangian in question is linear in the bubble acceleration and by means of the Ostrogradski-Hamiltonian approach we observed that the theory comprises the management of both first- and second-class constraints. We show thus that our second-order approach is robust allowing for a proper quantization. We found an effective quantum potential which permits to compute bounded states for the system. We comment on the possibility of describing brane world universes by invoking this kind of second-order correction terms.

  8. Viral membrane fusion

    Energy Technology Data Exchange (ETDEWEB)

    Harrison, Stephen C., E-mail: harrison@crystal.harvard.edu

    2015-05-15

    Membrane fusion is an essential step when enveloped viruses enter cells. Lipid bilayer fusion requires catalysis to overcome a high kinetic barrier; viral fusion proteins are the agents that fulfill this catalytic function. Despite a variety of molecular architectures, these proteins facilitate fusion by essentially the same generic mechanism. Stimulated by a signal associated with arrival at the cell to be infected (e.g., receptor or co-receptor binding, proton binding in an endosome), they undergo a series of conformational changes. A hydrophobic segment (a “fusion loop” or “fusion peptide”) engages the target-cell membrane and collapse of the bridging intermediate thus formed draws the two membranes (virus and cell) together. We know of three structural classes for viral fusion proteins. Structures for both pre- and postfusion conformations of illustrate the beginning and end points of a process that can be probed by single-virion measurements of fusion kinetics. - Highlights: • Viral fusion proteins overcome the high energy barrier to lipid bilayer merger. • Different molecular structures but the same catalytic mechanism. • Review describes properties of three known fusion-protein structural classes. • Single-virion fusion experiments elucidate mechanism.

  9. Surface glycosylation of polymeric membranes

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    Surface glycosylation of polymeric membranes has been inspired by the structure of natural biomem-branes. It refers to that glycosyl groups are introduced onto the membrane surface by various strate-gies, which combine the separation function of the membrane with the biological function of the sac-charides in one system. In this review, progress in the surface glycosylation of polymeric membranes is highlighted in two aspects, i.e. the glycosylation methods and the potential applications of the sur-face-glycosylated membranes.

  10. [Effect of Membrane Wettability on Membrane Fouling and Chemical Durability of SPG Membranes].

    Science.gov (United States)

    Zhang, Jing; Xiao, Tai-min; Zhang, Jing; Cao, Li-ya; Du, Ya-wei; Liu, Chun; Zhang, Lei

    2015-05-01

    Shirasu porous glass (SPG) membranes have been applied for microbubble aeration in aerobic wastewater treatment. In the present study, both hydrophilic and hydrophobic SPG membranes were used in a microbubble-aerated biofilm reactor with online chemical cleaning, and their membrane fouling and chemical durability were determined to be strongly dependent on the membrane wettability. The fouling layer formed on the surface of both membranes was confirmed to be mainly organic fouling, and the hydrophobic membrane showed a relatively stronger resistance to the organic fouling. The severe chemical corrosion of the hydrophilic membrane was observed due to exposure to the alkaline sodium hypochlorite solution used for chemical cleaning, which resulted in significant increases in the median pore diameter and the porosity. On the other hand, the pore structure of the hydrophobic membrane changed slightly when exposed to the alkaline sodium hypochlorite solution, suggesting its strong alkali-resistance due to the non-wetting surface. However, the surface hydrophobic groups of hydrophobic membrane could be oxidized by sodium hypochlorite solution, resulting in more wettable membrane surface. The hydrophobic membrane also showed better performance in the respects of oxygen transfer, contaminant removal and energy-saving. Therefore, the hydrophobic membrane seemed more appropriate to be applied for microbubble aeration in aerobic wastewater treatment process.

  11. Solid-state membrane module

    Science.gov (United States)

    Gordon, John Howard; Taylor, Dale M.

    2011-06-07

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

  12. Bleb Nucleation through Membrane Peeling

    CERN Document Server

    Alert, Ricard

    2016-01-01

    We study the nucleation of blebs, i.e., protrusions arising from a local detachment of the membrane from the cortex of a cell. Based on a simple model of elastic linkers with force-dependent kinetics, we show that bleb nucleation is governed by membrane peeling. By this mechanism, the growth or shrinkage of a detached membrane patch is completely determined by the linker kinetics, regardless of the energetic cost of the detachment. We predict the critical nucleation radius for membrane peeling and the corresponding effective energy barrier. These may be typically smaller than those predicted by classical nucleation theory, implying a much faster nucleation. We also perform simulations of a continuum stochastic model of membrane-cortex adhesion to obtain the statistics of bleb nucleation times as a function of the stress on the membrane. The determinant role of membrane peeling changes our understanding of bleb nucleation and opens new directions in the study of blebs.

  13. CHARMM-GUI Membrane Builder toward realistic biological membrane simulations.

    Science.gov (United States)

    Wu, Emilia L; Cheng, Xi; Jo, Sunhwan; Rui, Huan; Song, Kevin C; Dávila-Contreras, Eder M; Qi, Yifei; Lee, Jumin; Monje-Galvan, Viviana; Venable, Richard M; Klauda, Jeffery B; Im, Wonpil

    2014-10-15

    CHARMM-GUI Membrane Builder, http://www.charmm-gui.org/input/membrane, is a web-based user interface designed to interactively build all-atom protein/membrane or membrane-only systems for molecular dynamics simulations through an automated optimized process. In this work, we describe the new features and major improvements in Membrane Builder that allow users to robustly build realistic biological membrane systems, including (1) addition of new lipid types, such as phosphoinositides, cardiolipin (CL), sphingolipids, bacterial lipids, and ergosterol, yielding more than 180 lipid types, (2) enhanced building procedure for lipid packing around protein, (3) reliable algorithm to detect lipid tail penetration to ring structures and protein surface, (4) distance-based algorithm for faster initial ion displacement, (5) CHARMM inputs for P21 image transformation, and (6) NAMD equilibration and production inputs. The robustness of these new features is illustrated by building and simulating a membrane model of the polar and septal regions of E. coli membrane, which contains five lipid types: CL lipids with two types of acyl chains and phosphatidylethanolamine lipids with three types of acyl chains. It is our hope that CHARMM-GUI Membrane Builder becomes a useful tool for simulation studies to better understand the structure and dynamics of proteins and lipids in realistic biological membrane environments.

  14. Polyazole hollow fiber membranes for direct contact membrane distillation

    KAUST Repository

    Maab, Husnul

    2013-08-07

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

  15. Membrane fouling control by ultrasound in an anaerobic membrane bioreactor

    Institute of Scientific and Technical Information of China (English)

    SUI Pengzhe; WEN Xianghua; HUANG Xia

    2007-01-01

    In this study,ultrasound was used to control the membrane fouling online in an anaerobic membrane bioreactor (AMBR).Short-term running experiments were carried out under different operating conditions to explore feasible ultrasonic parameters.The experimental results indicated that when the crossflow velocity was more than 1.0 m/s,membrane fouling could be controlled effectively only by hydrodynamic methods without ultrasound.When ultrasound was applied,an ultrasonic power range of 60-150 W was suitable for the membrane fouling control in the experimental system.The experimental results showed that the membrane fouling was controlled so well that membrane filtration resistance(ΣR) could stay at 5×1011 m-1 for more than a week with the crossflow velocity of 0.75 m/s,which equaled the effect of crossflow velocity of more than 1.0 m/s without ultrasound.

  16. Chemical degradation mechanisms of membranes for alkaline membrane fuel cells

    Energy Technology Data Exchange (ETDEWEB)

    Choe, Yoong-Kee [National Institute of Advanced Industrial Science and Technology, Umezono 1-1-1, Tsukuba (Japan); Henson, Neil J.; Kim, Yu Seung [Los Alamos National Laboratory, Los Alamos, NM (United States)

    2015-12-31

    Chemical degradation mechanisms of membranes for alkaline membrane fuel cells have been investigated using density functional theory (DFT). We have elucidated that the aryl-ether moiety of membranes is one of the weakest site against attack of hydroxide ions. The results of DFT calculations for hydroxide initiated aryl-ether cleavage indicated that the aryl-ether cleavage occurred prior to degradation of cationic functional group. Such a weak nature of the aryl-ether group arises from the electron deficiency of the aryl group as well as the low bond dissociation energy. The DFT results suggests that removal of the aryl-ether group in the membrane should enhance the stability of membranes under alkaline conditions. In fact, an ether fee poly(phenylene) membrane exhibits excellent stability against the attack from hydroxide ions.

  17. Oxygen Transport Ceramic Membranes

    Energy Technology Data Exchange (ETDEWEB)

    S. Bandopadhyay; T. Nithyanantham; X.-D Zhou; Y-W. Sin; H.U. Anderson; Alan Jacobson; C.A. Mims

    2005-02-01

    The present quarterly report describes some of the investigations on the structural properties of dense OTM bars provided by Praxair and studies on newer composition of Ti doped LSF. The in situ electrical conductivity and Seebeck coefficient measurements were made on LSFT at 1000 and 1200 C over the oxygen activity range from air to 10{sup -15} atm. The electrical conductivity measurements exhibited a p to n type transition at an oxygen activity of 1 x 10{sup -10} at 1000 C and 1 x 10{sup -6} at 1200 C. Thermogravimetric studies were also carried out over the same oxygen activities and temperatures. Based on the results of these measurements, the chemical and mechanical stability range of LSFT were determined and defect structure was established. The studies on the fracture toughness of the LSFT and dual phase membranes exposed to air and N{sub 2} at 1000 C was done and the XRD and SEM analysis of the specimens were carried out to understand the structural and microstructural changes. The membranes that are exposed to high temperatures at an inert and a reactive atmosphere undergo many structural and chemical changes which affect the mechanical properties. A complete transformation of fracture behavior was observed in the N{sub 2} treated LSFT samples. Further results to investigate the origin of the slow kinetics on reduction of ferrites have been obtained. The slow kinetics appear to be related to a non-equilibrium reduction pathway that initially results in the formation of iron particles. At long times, equilibrium can be reestablished with recovery of the perovskite phase. Recent results on transient kinetic data are presented. The 2-D modeling of oxygen movement has been undertaken in order to fit isotope data. The model is used to study ''frozen'' profiles in patterned or composite membranes.

  18. Oxygen Transport Ceramic Membranes

    Energy Technology Data Exchange (ETDEWEB)

    S. Bandopadhyay; T. Nithyanantham; X.-D Zhou; Y-W. Sin; H.U. Anderson; Alan Jacobson; C.A. Mims

    2005-08-01

    The present quarterly report describes some of the investigations on the structural properties of dense OTM bars provided by Praxair and studies on newer composition of Ti doped LSF. In the previous research, the reference point of oxygen occupancy was determined and verified. In the current research, the oxygen occupancy was investigated at 1200 C as a function of oxygen activity and compared with that at 1000 C. The cause of bumps at about 200 C was also investigated by using different heating and cooling rates during TGA. The fracture toughness of LSFT and dual phase membranes at room temperature is an important mechanical property. Vicker's indentation method was used to evaluate this toughness. Through this technique, a K{sub Ic} (Mode-I Fracture Toughness) value is attained by means of semi-empirical correlations between the indentation load and the length of the cracks emanating from the corresponding Vickers indentation impression. In the present investigation, crack propagation behavior was extensively analyzed in order to understand the strengthening mechanisms involved in the non-transforming La based ceramic composites. Cracks were generated using Vicker's indenter and used to identify and evaluate the toughening mechanisms involved. Preliminary results of an electron microscopy study of the origin of the slow kinetics on reduction of ferrites have been obtained. The slow kinetics appear to be related to a non-equilibrium reduction pathway that initially results in the formation of iron particles. At long times, equilibrium can be reestablished with recovery of the perovskite phase. Modeling of the isotopic transients on operating membranes (LSCrF-2828 at 900 C) and a ''frozen'' isotope profile have been analyzed in conjunction with a 1-D model to reveal the gradient in oxygen diffusivity through the membrane under conditions of high chemical gradients.

  19. Electrically Conductive Porous Membrane

    Science.gov (United States)

    Burke, Kenneth Alan (Inventor)

    2014-01-01

    The present invention relates to an electrically conductive membrane that can be configured to be used in fuel cell systems to act as a hydrophilic water separator internal to the fuel cell, or as a water separator used with water vapor fed electrolysis cells, or as a water separator used with water vapor fed electrolysis cells, or as a capillary structure in a thin head pipe evaporator, or as a hydrophobic gas diffusion layer covering the fuel cell electrode surface in a fuel cell.

  20. Oxygen Transport Ceramic Membranes

    Energy Technology Data Exchange (ETDEWEB)

    S. Bandopadhyay; N. Nagabhushana; X.-D Zhou; Q. Cai; J. Yang; W.B. Yelon; W.J. James; H.U. Anderson; Alan Jacobson; C.A. Mims

    2004-05-01

    The present quarterly report describes some of the investigations on the structural properties of dense OTM bars provided by Praxair and studies on newer composition of Ti doped LSF. In this report, in situ neutron diffraction was used to characterize the chemical and structural properties of La{sub 0.2}Sr{sub 0.8}Fe{sub 0.55}Ti{sub 0.45}O{sub 3-{delta}} (here after as L2SF55T) specimen, which was subject to measurements of neutron diffraction from room temperature to 900 C. It was found that space group of R3c yielded a better refinement than a cubic structure of Pm3m. Oxygen occupancy was nearly 3 in the region from room temperature to 700 C, above which the occupancy decreased due to oxygen loss. Dense OTM bars provided by Praxair were loaded to fracture at varying stress rates. Studies were done at room temperature in air and at 1000 C in a specified environment to evaluate slow crack growth behavior. The X-Ray data and fracture mechanisms points to non-equilibrium decomposition of the LSFCO OTM membrane. The non-equilibrium conditions could probably be due to the nature of the applied stress field (stressing rates) and leads to transition in crystal structures and increased kinetics of decomposition. The formations of a Brownmillerite or Sr2Fe2O5 type structures, which are orthorhombic are attributed to the ordering of oxygen vacancies. The cubic to orthorhombic transitions leads to 2.6% increase in strains and thus residual stresses generated could influence the fracture behavior of the OTM membrane. Continued investigations on the thermodynamic properties (stability and phase-separation behavior) and total conductivity of prototype membrane materials were carried out. The data are needed together with the kinetic information to develop a complete model for the membrane transport. Previously characterization, stoichiometry and conductivity measurements for samples of La{sub 0.2}Sr{sub 0.8}Fe{sub 0.55}Ti{sub 0.45}O{sub 3-{delta}} were reported. In this report

  1. Oxygen Transport Membranes

    Energy Technology Data Exchange (ETDEWEB)

    S. Bandopadhyay

    2008-08-30

    The focus of this research was to develop new membrane materials by synthesizing different compounds and determining their defect structures, crystallographic structures and electrical properties. In addition to measuring electrical conductivity, oxygen vacancy concentration was also evaluated using thermogravimetry, Neutron diffraction and Moessbauer Spectroscopy. The reducing conditions (CO{sub 2}/CO/H{sub 2} gas mixtures with steam) as encountered in a reactor environment can be expected to have significant influence on the mechanical properties of the oxides membranes. Various La based materials with and without Ti were selected as candidate membrane materials for OTM. The maximum electrical conductivity of LSF in air as a function of temperature was achieved at < 600 C and depends on the concentration of Sr (acceptor dopant). Oxygen occupancy in LSF was estimated using Neutron diffractometry and Moessbauer Spectroscopy by measuring magnetic moment changes depending on the Fe{sup 3+} and Fe{sup 4+} ratio. After extensive studies of candidate materials, lanthanum ferrites (LSF and LSFT) were selected as the favored materials for the oxygen transport membrane (OTM). LSF is a very good material for an OTM because of its high electronic and oxygen ionic conductivity if long term stability and mechanical strength are improved. LSFT not only exhibits p-type behavior in the high oxygen activity regime, but also has n-type conduction in reducing atmospheres. Higher concentrations of oxygen vacancies in the low oxygen activity regime may improve the performance of LSFT as an OTM. The hole concentration is related to the difference in the acceptor and donor concentration by the relation p = [Sr'{sub La}]-[Ti{sm_bullet}{sub Fe}]. The chemical formulation predicts that the hole concentration is, p = 0.8-0.45 or 0.35. Experimental measurements indicated that p is about {approx} 0.35. The activation energy of conduction is 0.2 eV which implies that LSCF conducts via the

  2. Molecularly Imprinted Membranes

    Directory of Open Access Journals (Sweden)

    Fabrizio Caldera

    2012-07-01

    Full Text Available Although the roots of molecularly imprinted polymers lie in the beginning of 1930s in the past century, they have had an exponential growth only 40–50 years later by the works of Wulff and especially by Mosbach. More recently, it was also proved that molecular imprinted membranes (i.e., polymer thin films that show recognition properties at molecular level of the template molecule are used in their formation. Different procedures and potential application in separation processes and catalysis are reported. The influences of different parameters on the discrimination abilities are also discussed.

  3. Membrane filters and membrane-filtration processes for health care.

    Science.gov (United States)

    Eudailey, W A

    1983-11-01

    The development of membrane-filtration processes is reviewed, and current types and uses of membrane filtration in health care is discussed. Development of adequate support structures for filters and of disposable filtration devices has facilitated development of filtration processes for pharmaceutical industry, manufacturing in hospital pharmacies, and direct patient care. Hydrophobic filters have also been developed; aqueous solutions cannot wet the pore structures of these filters and therefore cannot pass. Sterility-testing systems have also been developed. There are two types of filters: depth (constructed of compacted fibers) and membrane (which have a homogeneous internal structure). Depth filters retain only a portion of particles in a particular size range and are generally not acceptable for use in health care. Membrane filters retain all particles of a given size. Types of membrane filters are selected for specific uses based on needed flow rates, particulate load, and retention capability. Membrane filters may be validated using bacterial-passage, bubble-point, and diffusion tests. Most membrane filters used in health care are microporous filters that retain particles in the 0.1-10-micron size range. Applications are currently being developed for ultrafilters, which retain both particles and substances with large molecular structures such as proteins, and reverse-osmosis filter membranes, which allow only water or water-miscible solvents of very low molecular weights to pass. Experience in engineering designs, quality assurance, and test procedures has led to the development of many safe, reliable, and effective membrane products for health care.

  4. POLYMER ELECTROLYTE MEMBRANE FUEL CELLS

    DEFF Research Database (Denmark)

    2001-01-01

    A method for preparing polybenzimidazole or polybenzimidazole blend membranes and fabricating gas diffusion electrodes and membrane-electrode assemblies is provided for a high temperature polymer electrolyte membrane fuel cell. Blend polymer electrolyte membranes based on PBI and various...... thermoplastic polymers for high temperature polymer electrolyte fuel cells have also been developed. Miscible blends are used for solution casting of polymer membranes (solid electrolytes). High conductivity and enhanced mechanical strength were obtained for the blend polymer solid electrolytes...... electrolyte membrane by hot-press. The fuel cell can operate at temperatures up to at least 200 °C with hydrogen-rich fuel containing high ratios of carbon monoxide such as 3 vol% carbon monoxide or more, compared to the carbon monoxide tolerance of 10-20 ppm level for Nafion$m(3)-based polymer electrolyte...

  5. Mathematical modelling of membrane separation

    DEFF Research Database (Denmark)

    Vinther, Frank

    This thesis concerns mathematical modelling of membrane separation. The thesis consists of introductory theory on membrane separation, equations of motion, and properties of dextran, which will be the solute species throughout the thesis. Furthermore, the thesis consist of three separate...... mathematical models, each with a different approach to membrane separation. The first model is a statistical model investigating the interplay between solute shape and the probability of entering the membrane. More specific the transition of solute particles from being spherical to becoming more elongated...... as prolate ellipsoids with the same volume. The porous membrane is assumed isotropic such that the model reduces to a two dimensional model. With this assumption ellipsoids with the same volume reduces to ellipses with the same area. The model finds the probability of entering the pore of the membrane...

  6. Catalytic Membrane Sensors

    Energy Technology Data Exchange (ETDEWEB)

    Boyle, T.J.; Brinker, C.J.; Gardner, T.J.; Hughes, R.C.; Sault, A.G.

    1998-12-01

    The proposed "catalytic membrane sensor" (CMS) was developed to generate a device which would selectively identify a specific reagent in a complex mixture of gases. This was to be accomplished by modifying an existing Hz sensor with a series of thin films. Through selectively sieving the desired component from a complex mixture and identifying it by decomposing it into Hz (and other by-products), a Hz sensor could then be used to detect the presence of the select component. The proposed "sandwich-type" modifications involved the deposition of a catalyst layered between two size selective sol-gel layers on a Pd/Ni resistive Hz sensor. The role of the catalyst was to convert organic materials to Hz and organic by-products. The role of the membraneo was to impart both chemical specificity by molecukir sieving of the analyte and converted product streams, as well as controlling access to the underlying Pd/Ni sensor. Ultimately, an array of these CMS elements encompassing different catalysts and membranes were to be developed which would enable improved selectivity and specificity from a compiex mixture of organic gases via pattern recognition methodologies. We have successfully generated a CMS device by a series of spin-coat deposited methods; however, it was determined that the high temperature required to activate the catalyst, destroys the sensor.

  7. Impact on floating membranes

    Science.gov (United States)

    Vandenberghe, Nicolas; Duchemin, Laurent

    2016-05-01

    When impacted by a rigid body, a thin elastic membrane with negligible bending rigidity floating on a liquid pool deforms. Two axisymmetric waves radiating from the impact point propagate. First, a longitudinal wave front, associated with in-plane deformation of the membrane and traveling at constant speed, separates an outward stress-free domain from a stretched domain. Then, in the stretched domain a dispersive transverse wave travels at a speed that depends on the local stretching rate. The dynamics is found to be self-similar in time. Using this property, we show that the wave dynamics is similar to the capillary waves that propagate at a liquid-gas interface but with a surface tension coefficient that depends on impact speed. During wave propagation, we observe the development of a buckling instability that gives rise to radial wrinkles. We address the dynamics of this fluid-body system, including the rapid deceleration of an impactor of finite mass, an issue that may have applications in the domain of absorption of impact energy.

  8. Composite oxygen transport membrane

    Energy Technology Data Exchange (ETDEWEB)

    Lu, Zigui; Plonczak, Pawel J.; Lane, Jonathan A.

    2016-11-08

    A method is described of producing a composite oxygen ion membrane and a composite oxygen ion membrane in which a porous fuel oxidation layer and a dense separation layer and optionally, a porous surface exchange layer are formed on a porous support from mixtures of (Ln.sub.1-xA.sub.x).sub.wCr.sub.1-yB.sub.yO.sub.3-.delta. and a doped zirconia. Preferred materials are (La.sub.0.8Sr.sub.0.2).sub.0.95Cr.sub.0.7Fe.sub.0.3O.sub.3-.delta. for the porous fuel oxidation layer, (La.sub.0.8Sr.sub.0.2).sub.0.95Cr.sub.0.5Fe.sub.0.5O.sub.3-.delta. for the dense separation layer, and (La.sub.0.8Sr.sub.0.2).sub.0.95Cr.sub.0.3Fe.sub.0.7O.sub.3-.delta. for the porous surface exchange layer. Firing the said fuel activation and separation layers in nitrogen atmosphere unexpectedly allows the separation layer to sinter into a fully densified mass.

  9. Membrane fouling and wetting in membrane distillation and their mitigation by novel membranes with special wettability.

    Science.gov (United States)

    Wang, Zhangxin; Lin, Shihong

    2017-04-01

    Membrane distillation (MD) has been identified as a promising technology to desalinate the hypersaline wastewaters from fracking and other industries. However, conventional hydrophobic MD membranes are highly susceptible to fouling and/or wetting by the hydrophobic and/or amphiphilic constituents in these wastewaters of complex compositions. This study systematically investigates the impact of the surface wetting properties on the membrane wetting and/or fouling behaviors in MD. Specifically, we compare the wetting and fouling resistance of three types of membranes of different wetting properties, including hydrophobic and omniphobic membranes as well as composite membranes with a hydrophobic substrate and a superhydrophilic top surface. We challenged the MD membranes with hypersaline feed solutions that contained a relatively high concentration of crude oil with and without added synthetic surfactants, Triton X-100. We found that the composite membranes with superhydrophilic top surface were robustly resistant to oil fouling in the absence of Triton X-100, but were subject to pore wetting in the presence of Triton X-100. On the other hand, the omniphobic membranes were easily fouled by oil-in-water emulsion without Triton X-100, but successfully sustained stable MD performance with Triton X-100 stabilized oil-in-water emulsion as the feed solution. In contrast, the conventional hydrophobic membranes failed readily regardless whether Triton X-100 was present, although via different mechanisms. These findings are corroborated by contact angle measures as well as oil-probe force spectroscopy. This study provides a holistic picture regarding how a hydrophobic membrane fails in MD and how we can leverage membranes with special wettability to prevent membrane failure in MD operations.

  10. Thermal treatment for nanofibrous membrane

    Directory of Open Access Journals (Sweden)

    Liu Hong-Ying

    2014-01-01

    Full Text Available Poly(vinylidene fluoride nanofibrous membranes with high porosity, large electrolyte solution uptake, and adequate mechanical properties were prepared by electrospinning. The physical properties of the electrospun poly(vinylidene fluoride membranes can be improved by thermal treatment. Results showed after the thermal treatment, there had appeared ever-increasing tensile strength and elongation of the poly(vinylidene fluoride membranes. The crystal structures of poly(vinylidene fluoride fibers were greatly improved.

  11. Relaxant Effect of Daurinoline on Vascular Smooth Muscle of Isolated Rabbit Basilar Artery%蝙蝠葛诺林碱对家兔体外基底动脉血管平滑肌舒张作用的研究

    Institute of Scientific and Technical Information of China (English)

    陈密; 崔海东; 郝素芳; 卢云; 郭莲军

    2014-01-01

    Objective To investigate the effect of daurinoline on basilar artery vascular smooth muscle. Methods The tension of isolated basilar artery ring of rabbit was measured. The effects of daurinoline on the basilar artery contracted by methoxamine,5-hydroxytryptamine(5-HT),KCl and Histamine( His)were also examined. Dose-response curves of 5-HT and KCl were observed as well. Results Daurinoline exerted obvious relaxation effect on the basilar artery vascular ring contracted by methoxamine,5-HT,KCl and His in a concentration-dependent manner. IC50 of daurinoline in methoxamine,5-HT,KCl and His-treated rabbits was 8.67×10-5,1.78×10-6,6.79×10-7 and 4.98×10-4 mol·L-1,respectively. The change of concentration-response curves of methoxamine,5-HT,KCl and His showed that daurinoline was a non-competitive antagonist. Conclusion Daurinoline exerts marked relaxation effect on basilar artery of rabbits through non-competitive antagonism. The mechanism of relaxation action may be related to blockage of voltage-dependent or receptor-dependent calcium channels.%目的:探讨蝙蝠葛诺林碱对家兔基底动脉血管平滑肌的舒张作用。方法制备家兔基底动脉血管环,采用半对数摩尔浓度累积给药方法,观察给予蝙蝠葛诺林碱对家兔基底动脉血管平滑肌的舒张作用。结果蝙蝠葛诺林碱对甲氧胺、5-羟色胺、氯化钾和组胺所致的家兔基底动脉收缩均有明显的扩张作用,最大舒张50%( IC50)浓度分别为8.67×10-5,1.78×10-6,6.79×10-7,4.98×10-4 mol·L-1。同时对甲氧胺、5-羟色胺、氯化钾和组胺所致量效曲线的影响,均显示为非竞争性拮抗作用。结论蝙蝠葛诺林碱通过非竞争性拮抗作用,能有效舒张家兔基底动脉血管平滑肌,改善脑循环。

  12. Composite membrane with integral rim

    Science.gov (United States)

    Routkevitch, Dmitri; Polyakov, Oleg G

    2015-01-27

    Composite membranes that are adapted for separation, purification, filtration, analysis, reaction and sensing. The composite membranes can include a porous support structure having elongate pore channels extending through the support structure. The composite membrane also includes an active layer comprising an active layer material, where the active layer material is completely disposed within the pore channels between the surfaces of the support structure. The active layer is intimately integrated within the support structure, thus enabling great robustness, reliability, resistance to mechanical stress and thermal cycling, and high selectivity. Methods for the fabrication of composite membranes are also provided.

  13. Proton exchange membrane fuel cells

    CERN Document Server

    Qi, Zhigang

    2013-01-01

    Preface Proton Exchange Membrane Fuel CellsFuel CellsTypes of Fuel CellsAdvantages of Fuel CellsProton Exchange Membrane Fuel CellsMembraneCatalystCatalyst LayerGas Diffusion MediumMicroporous LayerMembrane Electrode AssemblyPlateSingle CellStackSystemCell Voltage Monitoring Module (CVM)Fuel Supply Module (FSM)Air Supply Module (ASM)Exhaust Management Module (EMM)Heat Management Module (HMM)Water Management Module (WMM)Internal Power Supply Module (IPM)Power Conditioning Module (PCM)Communications Module (COM)Controls Module (CM)SummaryThermodynamics and KineticsTheoretical EfficiencyVoltagePo

  14. Permeability testing of biomaterial membranes

    Energy Technology Data Exchange (ETDEWEB)

    Dreesmann, L; Hajosch, R; Nuernberger, J Vaz; Schlosshauer, B [NMI Natural and Medical Sciences Institute at University Tuebingen, Markwiesenstr. 55, D-72770 Reutlingen (Germany); Ahlers, M [GELITA AG, Gammelsbacher Str. 2, D-69412 Eberbach (Germany)], E-mail: schlosshauer@nmi.de

    2008-09-01

    The permeability characteristics of biomaterials are critical parameters for a variety of implants. To analyse the permeability of membranes made from crosslinked ultrathin gelatin membranes and the transmigration of cells across the membranes, we combined three technical approaches: (1) a two-chamber-based permeability assay, (2) cell culturing with cytochemical analysis and (3) biochemical enzyme electrophoresis (zymography). Based on the diffusion of a coloured marker molecule in conjunction with photometric quantification, permeability data for a gelatin membrane were determined in the presence or absence of gelatin degrading fibroblasts. Cytochemical evaluation after cryosectioning of the membranes was used to ascertain whether fibroblasts had infiltrated the membrane inside. Zymography was used to investigate the potential release of proteases from fibroblasts, which are known to degrade collagen derivatives such as gelatin. Our data show that the diffusion equilibrium of a low molecular weight dye across the selected gelatin membrane is approached after about 6-8 h. Fibroblasts increase the permeability due to cavity formation in the membrane inside without penetrating the membrane for an extended time period (>21 days in vitro). Zymography indicates that cavity formation is most likely due to the secretion of matrix metalloproteinases. In summary, the combination of the depicted methods promises to facilitate a more rational development of biomaterials, because it provides a rapid means of determining permeability characteristics and bridges the gap between descriptive methodology and the mechanistic understanding of permeability alterations due to biological degradation.

  15. Characterization of Polymeric Nanofiltration Membranes

    Directory of Open Access Journals (Sweden)

    Simoncic, B.

    2007-11-01

    Full Text Available As membrane processes are increasingly used in industrial applications, there is a growing interest in methods of membrane characterization. Traditional membrane characteristics, such as cut-off value and pore size distribution, are being supplemented by membrane surface characteristics, such as charge density or zeta potential and hydrophobicity. This study, therefore, characterizes the three different polymeric membranes used (NFT-50, DL and DK. The molecular mass cut-off (MMCO value was determined using a set of reference solutes within the molecular range 150-600 Da, whereas streaming potential measurements enabled quantification of the surface charge characteristics. Hydrophobicity was studied using contact angle measurements. The results indicated that even though all three membranes had very similar layer compositions which consisted of poly(piperazneamide, as top layers they showed different values of measured quantitive. The NFT-50 membrane had the lowest MMCO value and the most hydrophilic membrane surface, followed by DK and DL. Membrane fouling as measured by flux reduction was determined by streaming potential measurements and accompanied by a positive change in zeta potential.

  16. Oxygen Transport Membranes

    Energy Technology Data Exchange (ETDEWEB)

    S. Bandopadhyay

    2008-08-30

    The focus of this research was to develop new membrane materials by synthesizing different compounds and determining their defect structures, crystallographic structures and electrical properties. In addition to measuring electrical conductivity, oxygen vacancy concentration was also evaluated using thermogravimetry, Neutron diffraction and Moessbauer Spectroscopy. The reducing conditions (CO{sub 2}/CO/H{sub 2} gas mixtures with steam) as encountered in a reactor environment can be expected to have significant influence on the mechanical properties of the oxides membranes. Various La based materials with and without Ti were selected as candidate membrane materials for OTM. The maximum electrical conductivity of LSF in air as a function of temperature was achieved at < 600 C and depends on the concentration of Sr (acceptor dopant). Oxygen occupancy in LSF was estimated using Neutron diffractometry and Moessbauer Spectroscopy by measuring magnetic moment changes depending on the Fe{sup 3+} and Fe{sup 4+} ratio. After extensive studies of candidate materials, lanthanum ferrites (LSF and LSFT) were selected as the favored materials for the oxygen transport membrane (OTM). LSF is a very good material for an OTM because of its high electronic and oxygen ionic conductivity if long term stability and mechanical strength are improved. LSFT not only exhibits p-type behavior in the high oxygen activity regime, but also has n-type conduction in reducing atmospheres. Higher concentrations of oxygen vacancies in the low oxygen activity regime may improve the performance of LSFT as an OTM. The hole concentration is related to the difference in the acceptor and donor concentration by the relation p = [Sr'{sub La}]-[Ti{sm_bullet}{sub Fe}]. The chemical formulation predicts that the hole concentration is, p = 0.8-0.45 or 0.35. Experimental measurements indicated that p is about {approx} 0.35. The activation energy of conduction is 0.2 eV which implies that LSCF conducts via the

  17. Self-Segregation of Myelin Membrane Lipids in Model Membranes

    NARCIS (Netherlands)

    Yurlova, Larisa; Kahya, Nicoletta; Aggarwal, Shweta; Kaiser, Hermann-Josef; Chiantia, Salvatore; Bakhti, Mostafa; Pewzner-Jung, Yael; Ben-David, Oshrit; Futerman, Anthony H.; Bruegger, Britta; Simons, Mikael

    2011-01-01

    Rapid conduction of nerve impulses requires coating of axons by myelin sheaths, which are multilamellar, lipid-rich membranes produced by oligodendrocytes in the central nervous system. To act as an insulator, myelin has to form a stable and firm membrane structure. In this study, we have analyzed t

  18. How Membrane-Active Peptides Get into Lipid Membranes.

    Science.gov (United States)

    Sani, Marc-Antoine; Separovic, Frances

    2016-06-21

    The structure-function relationship for a family of antimicrobial peptides (AMPs) from the skin of Australian tree frogs is discussed and compared with that of peptide toxins from bee and Australian scorpion venoms. Although these membrane-active peptides induce a similar cellular fate by disrupting the lipid bilayer integrity, their lytic activity is achieved via different modes of action, which are investigated in relation to amino acid sequence, secondary structure, and membrane lipid composition. In order to better understand what structural features govern the interaction between peptides and lipid membranes, cell-penetrating peptides (CPPs), which translocate through the membrane without compromising its integrity, are also discussed. AMPs possess membrane lytic activities that are naturally designed to target the cellular membrane of pathogens or competitors. They are extremely diverse in amino acid composition and often show specificity against a particular strain of microbe. Since our antibiotic arsenal is declining precariously in the face of the rise in multiantibiotic resistance, AMPs increasingly are seen as a promising alternative. In an effort to understand their molecular mechanism, biophysical studies of a myriad of AMPs have been reported, yet no unifying mechanism has emerged, rendering difficult the rational design of drug leads. Similarly, a wide variety of cytotoxic peptides are found in venoms, the best known being melittin, yet again, predicting their activity based on a particular amino acid composition or secondary structure remains elusive. A common feature of these membrane-active peptides is their preference for the lipid environment. Indeed, they are mainly unstructured in solution and, in the presence of lipid membranes, quickly adsorb onto the surface, change their secondary structure, eventually insert into the hydrophobic core of the membrane bilayer, and finally disrupt the bilayer integrity. These steps define the molecular

  19. Mechanisms of Membrane Curvature Generation in Membrane Traffic

    Directory of Open Access Journals (Sweden)

    Hye-Won Shin

    2012-02-01

    Full Text Available During the vesicular trafficking process, cellular membranes undergo dynamic morphological changes, in particular at the vesicle generation and fusion steps. Changes in membrane shape are regulated by small GTPases, coat proteins and other accessory proteins, such as BAR domain-containing proteins. In addition, membrane deformation entails changes in the lipid composition as well as asymmetric distribution of lipids over the two leaflets of the membrane bilayer. Given that P4-ATPases, which catalyze unidirectional flipping of lipid molecules from the exoplasmic to the cytoplasmic leaflets of the bilayer, are crucial for the trafficking of proteins in the secretory and endocytic pathways, changes in the lipid composition are involved in the vesicular trafficking process. Membrane remodeling is under complex regulation that involves the composition and distribution of lipids as well as assembly of proteins.

  20. Pretreatment and Membrane Hydrophilic Modification to Reduce Membrane Fouling

    Directory of Open Access Journals (Sweden)

    Huaqiang Chu

    2013-09-01

    Full Text Available The application of low pressure membranes (microfiltration/ultrafiltration has undergone accelerated development for drinking water production. However, the major obstacle encountered in its popularization is membrane fouling caused by natural organic matter (NOM. This paper firstly summarizes the two factors causing the organic membrane fouling, including molecular weight (MW and hydrophilicity/hydrophobicity of NOM, and then presents a brief introduction of the methods which can prevent membrane fouling such as pretreatment of the feed water (e.g., coagulation, adsorption, and pre-oxidation and membrane hydrophilic modification (e.g., plasma modification, irradiation grafting modification, surface coating modification, blend modification, etc.. Perspectives of further research are also discussed.

  1. Oxygen Transport Ceramic Membranes

    Energy Technology Data Exchange (ETDEWEB)

    S. Bandopadhyay; T. Nithyanantham

    2006-12-31

    Ti doping on La{sub 1-x}Sr{sub x}FeO{sub 3-{delta}} (LSF) tends to increase the oxygen equilibration kinetics of LSF in lower oxygen activity environment because of the high valence state of Ti. However, the addition of Ti decreases the total conductivity because the acceptor ([Sr{prime}{sub La}]) is compensated by the donor ([Ti{sub Fe}{sup {sm_bullet}}]) which decreases the carrier concentration. The properties of La{sub 0.2}Sr{sub 0.8}Fe{sub 1-x}Ti{sub x}O{sub 3-{delta}} (LSFT, x = 0.45) have been experimentally and theoretically investigated to elucidate (1) the dependence of oxygen occupancy and electrochemical properties on temperature and oxygen activity by thermogravimetric analysis (TGA) and (2) the electrical conductivity and carrier concentration by Seebeck coefficient and electrical measurements. In the present study, dual phase (La{sub 0.2}Sr{sub 0.8}Fe{sub 0.6}Ti{sub 0.4}O{sub 3-{delta}}/Ce{sub 0.9}Gd{sub 0.1}O{sub 2-{delta}}) membranes have been evaluated for structural properties such as hardness, fracture toughness and flexural strength. The effect of high temperature and slightly reducing atmosphere on the structural properties of the membranes was studied. The flexural strength of the membrane decreases upon exposure to slightly reducing conditions at 1000 C. The as-received and post-fractured membranes were characterized using XRD, SEM and TG-DTA to understand the fracture mechanisms. Changes in structural properties of the composite were sought to be correlated with the physiochemical features of the two-phases. We have reviewed the electrical conductivity data and stoichiometry data for La{sub 0.2}Sr{sub 0.8}Cr{sub 0.2}Fe{sub 0.8}O{sub 3-{delta}} some of which was reported previously. Electrical conductivity data for La{sub 0.2}Sr{sub 0.8}Cr{sub 0.2}Fe{sub 0.8}O{sub 3-{delta}} (LSCrF) were obtained in the temperature range, 752 {approx} 1055 C and in the pO{sub 2} range, 10{sup -18} {approx} 0.5 atm. The slope of the plot of log {sigma} vs

  2. High Flux Metallic Membranes for Hydrogen Recovery and Membrane Reactors

    Energy Technology Data Exchange (ETDEWEB)

    Buxbaum, Robert

    2010-06-30

    We made and tested over 250 new alloys for use as lower cost, higher flux hydrogen extraction membrane materials. Most of these were intermetallic, or contained significant intermetallic content, particularly based on B2 alloy compositions with at least one refractory component; B2 intermetallics resemble BCC alloys, in structure, but the atoms have relatively fixed positions, with one atom at the corners of the cube, the other at the centers. The target materals we were looking for would contain little or no expensive elements, no strongly toxic or radioactive elements, would have high flux to hydrogen, while being fabricable, brazable, and relatively immune to hydrogen embrittlement and corrosion in operation. The best combination of properties of the membrane materials we developed was, in my opinion, a Pd-coated membrane consisting of V -9 atomic % Pd. This material was relatively cheap, had 5 times the flux of Pd under the same pressure differential, was reasonably easy to fabricate and braze, and not bad in terms of embrittlement. Based on all these factors we project, about 1/3 the cost of Pd, on an area basis for a membrane designed to last 20 years, or 1/15 the cost on a flux basis. Alternatives to this membrane replaced significant fractions of the Pd with Ni and or Co. The cost for these membranes was lower, but so was the flux. We produced successful brazed products from the membrane materials, and made them into flat sheets. We tested, unsuccessfully, several means of fabricating thematerials into tubes, and eventually built a membrane reactor using a new, flat-plate design: a disc and doughnut arrangement, a design that seems well- suited to clean hydrogen production from coal. The membranes and reactor were tested successfully at Western Research. A larger equipment company (Chart Industries) produced similar results using a different flat-plate reactor design. Cost projections of the membrane are shown to be attractive.

  3. The leptospiral outer membrane.

    Science.gov (United States)

    Haake, David A; Zückert, Wolfram R

    2015-01-01

    The outer membrane (OM) is the front line of leptospiral interactions with their environment and the mammalian host. Unlike most invasive spirochetes, pathogenic leptospires must be able to survive in both free-living and host-adapted states. As organisms move from one set of environmental conditions to another, the OM must cope with a series of conflicting challenges. For example, the OM must be porous enough to allow nutrient uptake, yet robust enough to defend the cell against noxious substances. In the host, the OM presents a surface decorated with adhesins and receptors for attaching to, and acquiring, desirable host molecules such as the complement regulator, Factor H.Factor H. On the other hand, the OM must enable leptospires to evade detection by the host's immune system on their way from sites of invasion through the bloodstream to the protected niche of the proximal tubule. The picture that is emerging of the leptospiral OM is that, while it shares many of the characteristics of the OMs of spirochetes and Gram-negative bacteria, it is also unique and different in ways that make it of general interest to microbiologists. For example, unlike most other pathogenic spirochetes, the leptospiral OM is rich in lipopolysaccharide (LPS). Leptospiral LPS is similar to that of Gram-negative bacteria but has a number of unique structural features that may explain why it is not recognized by the LPS-specific Toll-like receptor 4 of humans. As in other spirochetes, lipoproteins are major components of the leptospiral OM, though their roles are poorly understood. The functions of transmembrane outer membrane proteins (OMPs) in many cases are better understood, thanks to homologies with their Gram-negative counterparts and the emergence of improved genetic techniques. This chapter will review recent discoveries involving the leptospiral OM and its role in leptospiral physiology and pathogenesis.

  4. Exploratory study of 3D printing technique in the treatment of basilar invagination and atlantoaxial dislocation%3D打印技术在颅底凹陷合并寰枢椎脱位手术中的应用

    Institute of Scientific and Technical Information of China (English)

    尹一恒; 余新光; 佟怀宇; 徐弢; 王鹏; 乔广宇

    2015-01-01

    目的 探讨3D打印技术在颅底凹陷合并寰枢椎脱位手术中的临床应用价值.方法 2013年1至9月解放军总医院神经外科对10例行后路固定手术的颅底凹陷合并寰枢椎脱位患者进行3D模型打印,打印范围为颅底到C4椎体,对骨质结构和椎动脉进行颜色区分制作1∶1大小的模型.在模型上进行术前模拟置钉,探讨固定方式和最佳进钉点以避开椎动脉,获得个性化置钉数据后进行手术操作,对3D打印模型的置钉数据和实际临床结果进行对比分析.结果 3D打印模型模拟手术发现,10例均有C1后弓发育不良或与枕骨融合,无法行C1后弓螺钉,进钉点选择在C1侧块;C2螺钉根据模型个体化设计:3例椎动脉异常或C2椎弓根宽度<3.5 mm无法行椎弓根螺钉固定,其中1例行C2椎板螺钉,1例行C2~3经关节螺钉,1例因合并C2~3椎体融合行C3椎弓根螺钉;2例椎弓根宽度在3.5~4.0 mm,经评估后设计钉道仍行椎弓根螺钉固定;1例单侧C1侧块垂直脱位于C2前方,采用寰枢椎经关节螺钉固定;其余均行椎弓根螺钉.10例手术方案均与3D打印模拟方案一致,术后随访12~18个月,随访时患者临床症状均有改善,植骨融合率100%.结论 3D打印模型可全面评估骨性结构异常和椎动脉走向,有助于制定手术策略、设计置钉点和置钉角度,避免椎动脉和脊髓损伤,值得推广.%Objective To investigate the clinical application value of the 3D printing technique in the treatment of basilar invagination and atlantoaxial dislocation.Methods From January 2013 to September 2013,10 patients with basilar invagination and atlantoaxial dislocation needing posterior fixation undertook 3D printing modes at the Department of Neurosurgery in PLA General Hospital.The 1 ∶ 1 size models were established from skull base to C4 level with different colors between bone structures and vertebral arteries.The simulation of screw insertion was made to

  5. Lipids of the Golgi membrane

    NARCIS (Netherlands)

    van Meer, G.

    1998-01-01

    The thin membrane of the endoplasmic reticulum matures into the thick plasma membrane in the Golgi apparatus. Along the way, the concentrations of cholesterol and sphingolipids increase. Here, Gerrit van Meer discusses how this phenomenon may reflect an intricate lipid-protein sorting machinery. Syn

  6. Modelling of proteins in membranes

    DEFF Research Database (Denmark)

    Sperotto, Maria Maddalena; May, S.; Baumgaertner, A.

    2006-01-01

    This review describes some recent theories and simulations of mesoscopic and microscopic models of lipid membranes with embedded or attached proteins. We summarize results supporting our understanding of phenomena for which the activities of proteins in membranes are expected to be significantly...

  7. Membranes from academia to industry

    Science.gov (United States)

    2017-02-01

    Andrew Livingston (Imperial College London) and Richard Baker (Membrane Technology and Research) talk to Nature Materials about the perks and pitfalls of membrane research and development, and how activities at the new Barrer Centre might lead to next-generation separation technologies.

  8. A membrane - foulant interaction study.

    NARCIS (Netherlands)

    Fontyn, M.

    1991-01-01

    In this thesis the problem of membrane fouling has been considered from different points of view. The aim of the study is to gather information on the physical and chemical mechanisms of membrane fouling, so that selective solutions can be introduced to overcome or to diminish the problem.Anti-foami

  9. Asymmetry effects in membrane catalysis

    NARCIS (Netherlands)

    Teplyakov, V. V.; Pisarev, G. I.; Magsumov, M. I.; Tsodikov, M. V.; Zhu, W.; Kapteijn, F.

    2006-01-01

    Catalytic processes using porous ceramic where catalytic coatings on the microchannel walls are of current interest for the creation of high speed and compact membrane reactors, especially for the reactions of C-1-substrates. Nanoporous ceramic membranes with variation of pore size as a non-linear g

  10. 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.

  11. Lipid membranes on nanostructured silicon.

    Energy Technology Data Exchange (ETDEWEB)

    Slade, Andrea Lynn; Lopez, Gabriel P. (University of New Mexico, Albuquerque, NM); Ista, Linnea K. (University of New Mexico, Albuquerque, NM); O' Brien, Michael J. (University of New Mexico, Albuquerque, NM); Sasaki, Darryl Yoshio; Bisong, Paul (University of New Mexico, Albuquerque, NM); Zeineldin, Reema R. (University of New Mexico, Albuquerque, NM); Last, Julie A.; Brueck, Stephen R. J. (University of New Mexico, Albuquerque, NM)

    2004-12-01

    A unique composite nanoscale architecture that combines the self-organization and molecular dynamics of lipid membranes with a corrugated nanotextured silicon wafer was prepared and characterized with fluorescence microscopy and scanning probe microscopy. The goal of this project was to understand how such structures can be assembled for supported membrane research and how the interfacial interactions between the solid substrate and the soft, self-assembled material create unique physical and mechanical behavior through the confinement of phases in the membrane. The nanometer scale structure of the silicon wafer was produced through interference lithography followed by anisotropic wet etching. For the present study, a line pattern with 100 nm line widths, 200 nm depth and a pitch of 360 nm pitch was fabricated. Lipid membranes were successfully adsorbed on the structured silicon surface via membrane fusion techniques. The surface topology of the bilayer-Si structure was imaged using in situ tapping mode atomic force microscopy (AFM). The membrane was observed to drape over the silicon structure producing an undulated topology with amplitude of 40 nm that matched the 360 nm pitch of the silicon structure. Fluorescence recovery after photobleaching (FRAP) experiments found that on the microscale those same structures exhibit anisotropic lipid mobility that was coincident with the silicon substructure. The results showed that while the lipid membrane maintains much of its self-assembled structure in the composite architecture, the silicon substructure indeed influences the dynamics of the molecular motion within the membrane.

  12. Bacteria/virus filter membrane

    Science.gov (United States)

    Lysaght, M. S.; Goodwin, F.; Roebelen, G.

    1977-01-01

    Hollow acrylate fiber membrane that filters bacterial and viral organisms can be used with closed-cycle life-support systems for underwater habitations or laboratories. Membrane also has applications in fields of medicine, gnotobiotics, pharmaceutical production, and industries and research facilities that require sterile water. Device eliminates need for strong chemicals or sterilizing agents, thereby reducing costs.

  13. Pore dynamics in lipid membranes

    Science.gov (United States)

    Gozen, I.; Dommersnes, P.

    2014-09-01

    Transient circular pores can open in plasma membrane of cells due to mechanical stress, and failure to repair such pores lead to cell death. Similar pores in the form of defects also exist among smectic membranes, such as in myelin sheaths or mitochondrial membranes. The formation and growth of membrane defects are associated with diseases, for example multiple sclerosis. A deeper understanding of membrane pore dynamics can provide a more refined picture of membrane integrity-related disease development, and possibly also treatment options and strategies. Pore dynamics is also of great importance regarding healthcare applications such as drug delivery, gene or as recently been implied, cancer therapy. The dynamics of pores significantly differ in stacks which are confined in 2D compared to those in cells or vesicles. In this short review, we will summarize the dynamics of different types of pores that can be observed in biological membranes, which include circular transient, fusion and hemi-fusion pores. We will dedicate a section to floral and fractal pores which were discovered a few years ago and have highly peculiar characteristics. Finally, we will discuss the repair mechanisms of large area pores in conjunction with the current cell membrane repair hypotheses.

  14. Electro-catalytic membrane reactors and the development of bipolar membrane technology

    NARCIS (Netherlands)

    Balster, J.; Stamatialis, D.F.; Wessling, M.

    2004-01-01

    Membrane reactors are currently under extensive research and development. Hardly any concept, however, is realized yet in practice. Frequently, forgotten as membrane reactors are electro-catalytic membrane reactors where electrodes perform chemical conversations and membranes separate the locations

  15. 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...

  16. Basement membrane proteoglycans and development

    DEFF Research Database (Denmark)

    Couchman, J R; Abrahamson, D R; McCarthy, K J

    1993-01-01

    Basement membranes contain distinct collagen, glycoprotein and proteoglycan species, and these exhibit considerable heterogeneity in isoform or type when different tissue types are compared. Additionally, many components are differentially expressed in organogenesis. We have considered the distri......Basement membranes contain distinct collagen, glycoprotein and proteoglycan species, and these exhibit considerable heterogeneity in isoform or type when different tissue types are compared. Additionally, many components are differentially expressed in organogenesis. We have considered...... the distributions in glomerulogenesis of two distinct basement membrane proteoglycans, a small heparan sulfate proteoglycan and a chondroitin sulfate proteoglycan (BM-CSPG). While the former was present in all kidney basement membranes through development, the latter was apparently regulated in distribution. BM......-CSPG was only strongly expressed in the vasculature invading late comma stage glomeruli, and later in presumptive and mature Bowman's capsule. Over the first six to eight weeks, the capillary basement membranes contained BM-CSPG, but in gradually decreasing amounts until it became completely undetectable...

  17. Staged membrane oxidation reactor system

    Science.gov (United States)

    Repasky, John Michael; Carolan, Michael Francis; Stein, VanEric Edward; Chen, Christopher Ming-Poh

    2013-04-16

    Ion transport membrane oxidation system comprising (a) two or more membrane oxidation stages, each stage comprising a reactant zone, an oxidant zone, one or more ion transport membranes separating the reactant zone from the oxidant zone, a reactant gas inlet region, a reactant gas outlet region, an oxidant gas inlet region, and an oxidant gas outlet region; (b) an interstage reactant gas flow path disposed between each pair of membrane oxidation stages and adapted to place the reactant gas outlet region of a first stage of the pair in flow communication with the reactant gas inlet region of a second stage of the pair; and (c) one or more reactant interstage feed gas lines, each line being in flow communication with any interstage reactant gas flow path or with the reactant zone of any membrane oxidation stage receiving interstage reactant gas.

  18. 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

  19. Olefin separation membrane and process

    Science.gov (United States)

    Pinnau, Ingo; Toy, Lora G.; Casillas, Carlos

    1997-01-01

    A membrane and process for separating unsaturated hydrocarbons from fluid mixtures. The membrane and process differ from previously known membranes and processes, in that the feed and permeate streams can both be dry, the membrane need not be water or solvent swollen, and the membrane is characterized by a selectivity for an unsaturated hydrocarbon over a saturated hydrocarbon having the same number of carbon atoms of at least about 20, and a pressure-normalized flux of said unsaturated hydrocarbon of at least about 5.times.10.sup.-6 cm.sup.3 (STP)/cm.sup.2 .multidot.s.multidot.cmHg, said flux and selectivity being measured with a gas mixture containing said unsaturated and saturated hydrocarbons, and in a substantially dry environment.

  20. Ceramic membrane development in NGK

    Science.gov (United States)

    Araki, Kiyoshi; Sakai, Hitoshi

    2011-05-01

    NGK Insulators, Ltd. was established in 1919 to manufacture the electric porcelain insulators for power transmission lines. Since then, our business has grown as one of the world-leading ceramics manufacturing companies and currently supply with the various environmentally-benign ceramic products to worldwide. In this paper, ceramic membrane development in NGK is described in detail. We have been selling ceramic microfiltration (MF) membranes and ultra-filtration (UF) membranes for many years to be used for solid/liquid separation in various fields such as pharmaceutical, chemical, food and semiconductor industries. In Corporate R&D, new ceramic membranes with sub-nanometer sized pores, which are fabricated on top of the membrane filters as support, are under development for gas and liquid/liquid separation processes.

  1. Ceramic membrane development in NGK

    Energy Technology Data Exchange (ETDEWEB)

    Araki, Kiyoshi; Sakai, Hitoshi, E-mail: kinsakai@ngk.co.jp [Corporate R and D, NGK Insulators, Ltd., Nagoya 467-8530 (Japan)

    2011-05-15

    NGK Insulators, Ltd. was established in 1919 to manufacture the electric porcelain insulators for power transmission lines. Since then, our business has grown as one of the world-leading ceramics manufacturing companies and currently supply with the various environmentally-benign ceramic products to worldwide. In this paper, ceramic membrane development in NGK is described in detail. We have been selling ceramic microfiltration (MF) membranes and ultra-filtration (UF) membranes for many years to be used for solid/liquid separation in various fields such as pharmaceutical, chemical, food and semiconductor industries. In Corporate R and D, new ceramic membranes with sub-nanometer sized pores, which are fabricated on top of the membrane filters as support, are under development for gas and liquid/liquid separation processes.

  2. Centrifugal membrane filtration -- Task 9

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1996-08-01

    The Energy and Environmental Research Center (EERC) has teamed with SpinTek Membrane Systems, Inc., the developer of a centrifugal membrane filtration technology, to demonstrate applications for the SpinTek technology within the US Department of Energy (DOE) Environmental management (EM) Program. The technology uses supported microporous membranes rotating at high rpm, under pressure, to separate suspended and colloidal solids from liquid streams, yielding a solids-free permeate stream and a highly concentrated solids stream. This is a crosscutting technology that falls under the Efficient Separations and Processing Crosscutting Program, with potential application to tank wastes, contaminated groundwater, landfill leachate, and secondary liquid waste streams from other remediation processes, including decontamination and decommissioning systems. Membrane-screening tests were performed with the SpinTek STC-X4 static test cell filtration unit, using five ceramic membranes with different pore size and composition. Based on permeate flux, a 0.25-{micro}m TiO{sub 2}/Al{sub 2}O{sub 3} membrane was selected for detailed performance evaluation using the SpinTek ST-IIL centrifugal membrane filtration unit with a surrogate tank waste solution. An extended test run of 100 hr performed on a surrogate tank waste solution showed some deterioration in filtration performance, based on flux, apparently due to the buildup of solids near the inner portion of the membrane where relative membrane velocities were low. Continued testing of the system will focus on modifications to the shear pattern across the entire membrane surface to affect improved long-term performance.

  3. Membrane alterations in irreversibly sickled cells: hemoglobin--membrane interaction.

    Science.gov (United States)

    Lessin, L S; Kurantsin-Mills, J; Wallas, C; Weems, H

    1978-01-01

    Irreversibly sickled cells (ISCs) are sickle erythrocytes which retain bipolar elongated shapes despite reoxygenation and owe their biophysical abnormalities to acquired membrane alterations. Freeze-etched membranes both of ISCs produced in vitro and ISCs isolated in vivo reveal microbodies fixed to the internal (PS) surface which obscure spectrin filaments. Intramembranous particles (IMPs) on the intramembrane (PF) surface aggregate over regions of subsurface microbodies. Electron microscopy of diaminobenzidine-treated of ISC ghosts show the microbodies to contain hemoglobin and/or hemoglobin derivatives. Scanning electron microscopy and freeze-etching demonstrate that membrane--hemoglobin S interaction in ISCs enhances the membrane loss by microspherulation. Membrane-bound hemoglobin is five times greater in in vivo ISCs than non-ISCs, and increases during ISC production, parallelling depletion of adenosine triphosphate. Polyacrylamide gel electrophoresis of ISC membranes shows the presence of high-molecular-weight heteropolymers in the pre--band 1 region, a decrease in band 4.1 and an increase in bands 7, 8, and globin. The role of cross-linked membrane protein polymers in the generation of ISCs is discussed and is synthesized in terms of a unified concept for the determinants of the genesis of ISCs.

  4. Electrospun superhydrophobic membranes with unique structures for membrane distillation.

    Science.gov (United States)

    Liao, Yuan; Loh, Chun-Heng; Wang, Rong; Fane, Anthony G

    2014-09-24

    With modest temperature demand, low operating pressure, and high solute rejection, membrane distillation (MD) is an attractive option for desalination, waste treatment, and food and pharmaceutical processing. However, large-scale practical applications of MD are still hindered by the absence of effective membranes with high hydrophobicity, high porosity, and adequate mechanical strength, which are important properties for MD permeation fluxes, stable long-term performance, and effective packing in modules without damage. This study describes novel design strategies for highly robust superhydrophobic dual-layer membranes for MD via electrospinning. One of the newly developed membranes comprises a durable and ultrathin 3-dimensional (3D) superhydrophobic skin and porous nanofibrous support whereas another was fabricated by electrospinning 3D superhydrophobic layers on a nonwoven support. These membranes exhibit superhydrophobicity toward distilled water, salty water, oil-in-water emulsion, and beverages, which enables them to be used not only for desalination but also for other processes. The superhydrophobic dual-layer membrane #3S-N with nanofibrous support has a competitive permeation flux of 24.6 ± 1.2 kg m(-2) h(-1) in MD (feed and permeate temperate were set as 333 and 293 K, respectively) due to the higher porosity of the nanofibrous scaffold. Meanwhile, the membranes with the nonwoven support exhibit greater mechanical strength due to this support combined with better long-term performance because of the thicker 3D superhydrophobic layers. The morphology, pore size, porosity, mechanical properties, and liquid enter pressure of water of these superhydrophobic composite membranes with two different structures are reported and compared with commercial polyvinylidene fluoride membranes.

  5. The Membrane: Transertion as an organizing principle in membrane heterogeneity

    Directory of Open Access Journals (Sweden)

    Kouji eMatsumoto

    2015-06-01

    Full Text Available The bacterial membrane exhibits a significantly heterogeneous distribution of lipids and proteins. This heterogeneity results mainly from lipid-lipid, protein-protein and lipid-protein associations which are orchestrated by the coupled transcription, translation and insertion of nascent proteins into and through membrane (transertion. Transertion is central not only to the individual assembly and disassembly of large physically linked groups of macromolecules (alias hyperstructures but also to the interactions between these hyperstructures. We review here these interactions in the context of the processes in Bacillus subtilis and Escherichia coli of nutrient sensing, membrane synthesis, cytoskeletal dynamics, DNA replication, chromosome segregation and cell division.

  6. Oxygen Transport Ceramic Membranes

    Energy Technology Data Exchange (ETDEWEB)

    S. Bandopadhyay; N. Nagabhushana; X.-D Zhou; Q. Cai; J. Yang; W.B. Yelon; W.J. James; H.U. Anderson; Alan Jacobson; C.A. Mims

    2004-10-01

    The present quarterly report describes some of the investigations on the structural properties of dense OTM bars provided by Praxair and studies on newer composition of Ti doped LSF. In this report, Moessbauer spectroscopy was used to study the local environmentals of LSFT with various level of oxygen deficiency. Ionic valence state, magnetic interaction and influence of Ti on superexchange are discussed Stable crack growth studies on Dense OTM bars provided by Praxair were done at elevated temperature, pressure and elevated conditions. Post-fracture X-ray data of the OTM fractured at 1000 C in environment were refined by FullProf code and results indicate a distortion of the parent cubic perovskite to orthorhombic structure with reduced symmetry. TGA-DTA studies on the post-fracture samples also indicated residual effect arising from the thermal and stress history of the samples. An electrochemical cell has been designed and built for measurements of the Seebeck coefficient as a function of temperature and pressure. The initial measurements on La{sub 0.2}Sr{sub 0.8}Fe{sub 0.55}Ti{sub 0.45}O{sub 3-{delta}} are reported. Neutron diffraction measurements of the same composition are in agreement with both the stoichiometry and the kinetic behavior observed in coulometric titration measurements. A series of isotope transients under air separation mode (small gradient) were completed on the membrane of LSCrF-2828 at 900 C. Low pO{sub 2} atmospheres based on with CO-CO{sub 2} mixtures have also been admitted to the delivery side of the LSCrF-2828 membrane to produce the gradients which exist under syngas generation conditions. The COCO{sub 2} mixtures have normal isotopic {sup 18}O abundances. The evolution of {sup 18}O on the delivery side in these experiments after an {sup 18}O pulse on the air side reveals a wealth of information about the oxygen transport processes.

  7. Inflation and Failure of Polymeric Membranes

    DEFF Research Database (Denmark)

    Hassager, Ole; Neergaard, Jesper

    2000-01-01

    We consider the inflation of an axisymmetric polymeric membrane.Some membranes composed of viscoelastic materialsdescribed by a Mooney-Rivlin model show a monotone increasingpressure during inflation. These materialsdevelop a homogeneous membrane thickness in agreement with the Considere-Pearson ......We consider the inflation of an axisymmetric polymeric membrane.Some membranes composed of viscoelastic materialsdescribed by a Mooney-Rivlin model show a monotone increasingpressure during inflation. These materialsdevelop a homogeneous membrane thickness in agreement with the Considere...

  8. 温泉游泳训练对飞行员椎-基底动脉血流动力学影响的研究%Research on the effects of swimming training in thermal spring on pilots'basilar vertebral artery hemodynamic changes

    Institute of Scientific and Technical Information of China (English)

    王忠波; 李欣; 段虹; 吴燕红; 姚永杰; 李建香

    2011-01-01

    Objective To observe the effects of swimming training in thermal spring on pilots' basilar vertebral artery ( BA) hemo-dynamic changes during the convalescence. Methods Twenty four healthy male pilots in active service were selected as subjects. During the period of convalescence they were arranged to perform a four-week swimming training program ( 5days/week). Their ver-tebral artery hemodynamic changes before and after training were measured with transcranial Doppler ultrasound apparatus. Results After four-week swimming training in thermal water, pilots' posterior cerebral artery ( PC A) , vertebral artery ( VA) , basilar ver-tebral artery (BA) , peak systolic velocity ( Vs) , diastasis velocity ( Vd) , average maximum velocity ( Vm) , pulsatility index (PI) , resistive index (RI) were compared with pre-training, the difference showed statistical significance ( P < 0. 01). Conclu-sion During the convalescence, swimming training in thermal spring can increase the flow velocity and vascular compliance of pos-terior cerebral artery ( PCA) , vertebral artery ( VA) and basilar vertebral artery (BA) to improve the hemodynamic index.%目的 观察健康疗养期间,温泉游泳训练对飞行员椎动脉血流动力学指标的影响.方法 24名飞行员在健康疗养期间,进行连续4周,每周5d的温泉游泳训练.训练前后采用经颅多普勒超声仪检测椎动脉血流动力学指标.结果 与训练前相比,游泳训练4周后飞行员双侧大脑后动脉(PCA)、双侧大脑椎动脉(VA)、基底动脉(BA)、收缩期峰值血流速度(Vs)、舒张末期血流速度(Vd)、峰值平均血流速度(Vm),脉动指数(PI)、阻力指数(RI),训练后与训练前比较,差异有统计学意义(P<0.01).结论 健康疗养期间,温泉游泳训练可提高大脑后动脉、椎动脉、基底动脉的血流速度及血管顺应性,明显改善血流动力学指标.

  9. Membrane manufacture for peptide separations

    KAUST Repository

    Kim, Dooli

    2016-06-07

    Nanostructured polymeric membranes are key tools in biomedical applications such as hemodialysis, protein separations, in the food industry, and drinking water supply from seawater. Despite of the success in different separation processes, membrane manufacture itself is at risk, since the most used solvents are about to be banned in many countries due to environmental and health issues. We propose for the first time the preparation of polyethersulfone membranes based on dissolution in the ionic liquid 1-ethyl-3-methylimidazolium dimethylphosphate ([EMIM]DEP). We obtained a series of membranes tailored for separation of solutes with molecular weight of 30, 5, 1.3, and 1.25 kg mol-1 with respective water permeances of 140, 65, 30 and 20 Lm-2h-1bar-1. We demonstrate their superior efficiency in the separation of complex mixtures of peptides with molecular weights in the range of 800 to 3500 gmol-1. Furthermore, the thermodynamics and kinetics of phase separation leading to the pore formation in the membranes were investigated. The rheology of the solutions and the morphology of the prepared membranes were examed and compared to those of polyethersulfone in organic solvents currently used for membrane manufacture.

  10. Gas Separations using Ceramic Membranes

    Energy Technology Data Exchange (ETDEWEB)

    Paul KT Liu

    2005-01-13

    This project has been oriented toward the development of a commercially viable ceramic membrane for high temperature gas separations. A technically and commercially viable high temperature gas separation membrane and process has been developed under this project. The lab and field tests have demonstrated the operational stability, both performance and material, of the gas separation thin film, deposited upon the ceramic membrane developed. This performance reliability is built upon the ceramic membrane developed under this project as a substrate for elevated temperature operation. A comprehensive product development approach has been taken to produce an economically viable ceramic substrate, gas selective thin film and the module required to house the innovative membranes for the elevated temperature operation. Field tests have been performed to demonstrate the technical and commercial viability for (i) energy and water recovery from boiler flue gases, and (ii) hydrogen recovery from refinery waste streams using the membrane/module product developed under this project. Active commercializations effort teaming with key industrial OEMs and end users is currently underway for these applications. In addition, the gas separation membrane developed under this project has demonstrated its economical viability for the CO2 removal from subquality natural gas and landfill gas, although performance stability at the elevated temperature remains to be confirmed in the field.

  11. [Giant vertebro-basilar aneurysm. Frontal syndrome].

    Science.gov (United States)

    Rosa, A; Mizon, J P; Sevestre, H

    1991-01-01

    A 72-year-old man presented with an apparent frontal syndrome. He also had bilateral trigeminal neuralgia, a pyramidal syndrome of all 4 limbs, balance disturbances, a horizontal nystagmus when looking to the left and a right velopalatine paralysis. CT scan with contrast showed a hyperdense rounded lesion in the left cerebello-pontine angle. Cerebral angiography showed this to be a large aneurysm of the end of the vertebral arteries. The patient died suddenly. Autopsy confirmed the site and presence of the aneurysm. Balance disturbances, the pyramidal syndrome and velopalatine paralysis could all be explained by brain stem compression and the bilateral nature of the trigeminal neuralgia by compression of the trigemino-thalamic tract. The apparent frontal syndrome, the authors suggest could have resulted from subacute raised intracranial pressure.

  12. Tympanic membrane gangrene

    Directory of Open Access Journals (Sweden)

    D R Surya Prakash

    2015-01-01

    Full Text Available Necrosis of tympanic membrane (TM can be due to infections, drugs, radiation, and foreign body. Strain of group A Streptococcus is associated with acute otitis media or in immunocompromised individuals resulting in TM necrosis. Gangrene of lower limb has been described, but the selective loss of TM due to emboli is an uncommon finding. A 62-year-old female presented with sudden behavioral changes and irrelevant talk. After 2 days, she noticed a discharge from left ear. There was perforation of left TM in posterior superior and inferior quadrant with areas of the black patch around the perforation suggesting a loss of blood supply. Patient was recently detected retrovirus positive with multiple lung shadows. Patient is not on any anti-retroviral medications or other medications. The discharge started 2 days after an episode of left middle cerebral artery infarct due to emboli with no previous history of ear symptoms. Culture of discharge showed no growth. This suggests that TM might have gone for gangrene due to emboli affecting deep auricular artery branch or posterior tympanic branch, which is a branch of the stylomastoid artery.

  13. Hierarchy in inorganic membranes.

    Science.gov (United States)

    Caro, Juergen

    2016-06-13

    Thin films of a few μm thickness for particle filtration and gas separation cannot be applied as self-supporting layers since they are mechanically insufficiently strong. Therefore, these top layers for particle filtration and gas separation are usually deposited on porous mechanically strong supports with a hierarchical pore structure. To reduce the pressure drop of a gas stream over the membrane and to ensure high fluxes in filtration and gas separation, the cross section of the support is usually asymmetric or graded with a small thickness of the layer with the smallest pore size called the top layer. Since the pressure drop over a capillary with radius r is ∼r(4), the layer with the smallest pore size should be as thin as possible. The disk-like planar supports are usually prepared by sequential tape casting which is an expensive technology. Tubular supports with a hierarchical cross section can be prepared in one step by hollow fiber spinning, double mantle spinning or centrifugal casting.

  14. Ultrastructure of Reissner's membrane in the rabbit

    DEFF Research Database (Denmark)

    Qvortrup, K.; Rostgaard, Jørgen; Bretlau, P.

    1994-01-01

    Anatomy, Reissner's membrane, electron microscopy, tubulocisternal endoplasmic reticulum, subsurface cisterns, rabbit......Anatomy, Reissner's membrane, electron microscopy, tubulocisternal endoplasmic reticulum, subsurface cisterns, rabbit...

  15. Experimental approaches to membrane thermodynamics

    DEFF Research Database (Denmark)

    Westh, Peter

    2009-01-01

    Thermodynamics describes a system on the macroscopic scale, yet it is becoming an important tool for the elucidation of many specific molecular aspects of membrane properties. In this note we discuss this application of thermodynamics, and give a number of examples on how thermodynamic measurements...... have contributed to the understanding of specific membrane phenomena. We mainly focus on non-specific interactions of bilayers and small molecules (water and solutes) in the surrounding solvent, and the changes in membrane properties they bring about. Differences between thermodynamic...

  16. Polyunsaturated Lipids Regulate Membrane Domain Stability by Tuning Membrane Order.

    Science.gov (United States)

    Levental, Kandice R; Lorent, Joseph H; Lin, Xubo; Skinkle, Allison D; Surma, Michal A; Stockenbojer, Emily A; Gorfe, Alemayehu A; Levental, Ilya

    2016-04-26

    The plasma membrane (PM) serves as the functional interface between a cell and its environment, hosting extracellular signal transduction and nutrient transport among a variety of other processes. To support this extensive functionality, PMs are organized into lateral domains, including ordered, lipid-driven assemblies termed lipid rafts. Although the general requirements for ordered domain formation are well established, how these domains are regulated by cell-endogenous mechanisms or exogenous perturbations has not been widely addressed. In this context, an intriguing possibility is that dietary fats can incorporate into membrane lipids to regulate the properties and physiology of raft domains. Here, we investigate the effects of polyunsaturated fats on the organization of membrane domains across a spectrum of membrane models, including computer simulations, synthetic lipid membranes, and intact PMs isolated from mammalian cells. We observe that the ω-3 polyunsaturated fatty acid docosahexaenoic acid is robustly incorporated into membrane lipids, and this incorporation leads to significant remodeling of the PM lipidome. Across model systems, docosahexaenoic acid-containing lipids enhance the stability of ordered raft domains by increasing the order difference between them and coexisting nonraft domains. The relationship between interdomain order disparity and the stability of phase separation holds for a spectrum of different perturbations, including manipulation of cholesterol levels and high concentrations of exogenous amphiphiles, suggesting it as a general feature of the organization of biological membranes. These results demonstrate that polyunsaturated fats affect the composition and organization of biological membranes, suggesting a potential mechanism for the extensive effects of dietary fat on health and disease.

  17. Effect of membrane polymeric materials on relationship between surface pore size and membrane fouling in membrane bioreactors

    Science.gov (United States)

    Miyoshi, Taro; Yuasa, Kotaku; Ishigami, Toru; Rajabzadeh, Saeid; Kamio, Eiji; Ohmukai, Yoshikage; Saeki, Daisuke; Ni, Jinren; Matsuyama, Hideto

    2015-03-01

    We investigated the effect of different membrane polymeric materials on the relationship between membrane pore size and development of membrane fouling in a membrane bioreactor (MBR). Membranes with different pore sizes were prepared using three different polymeric materials, cellulose acetate butyrate (CAB), polyvinyl butyral (PVB), and polyvinylidene fluoride (PVDF), and the development of membrane fouling in each membrane was evaluated by batch filtration tests using a mixed liquor suspension obtained from a laboratory-scale MBR. The results revealed that the optimal membrane pore size to mitigate membrane fouling differed depending on membrane polymeric material. For PVDF membranes, the degree of membrane fouling decreased as membrane pore size increased. In contrast, CAB membranes with smaller pores had less fouling propensity than those with larger ones. Such difference can be attributed to the difference in major membrane foulants in each membrane; in PVDF, they were small colloids or dissolved organics in which proteins are abundant, and in CAB, microbial flocs. The results obtained in this study strongly suggested that optimum operating conditions of MBRs differ depending on the characteristics of the used membrane.

  18. Lateral proton transfer between the membrane and a membrane protein.

    Science.gov (United States)

    Ojemyr, Linda; Sandén, Tor; Widengren, Jerker; Brzezinski, Peter

    2009-03-17

    Proton transport across biological membranes is a key step of the energy conservation machinery in living organisms, and it has been proposed that the membrane itself plays an important role in this process. In the present study we have investigated the effect of incorporation of a proton transporter, cytochrome c oxidase, into a membrane on the protonation kinetics of a fluorescent pH-sensitive probe attached at the surface of the protein. The results show that proton transfer to the probe was slightly accelerated upon attachment at the protein surface (approximately 7 x 1010 s(-1) M(-1), compared to the expected value of (1-2) x 10(10) s(-1) M(-1)), which is presumably due to the presence of acidic/His groups in the vicinity. Upon incorporation of the protein into small unilamellar phospholipid vesicles the rate increased by more than a factor of 400 to approximately 3 x 10(13) s(-1) M(-1), which indicates that the protein-attached probe is in rapid protonic contact with the membrane surface. The results indicate that the membrane acts to accelerate proton uptake by the membrane-bound proton transporter.

  19. Applicability of dynamic membrane technology in anaerobic membrane bioreactors.

    Science.gov (United States)

    Ersahin, Mustafa Evren; Ozgun, Hale; Tao, Yu; van Lier, Jules B

    2014-01-01

    This study investigated the applicability of dynamic membrane technology in anaerobic membrane bioreactors for the treatment of high strength wastewaters. A monofilament woven fabric was used as support material for dynamic membrane formation. An anaerobic dynamic membrane bioreactor (AnDMBR) was operated under a variety of operational conditions, including different sludge retention times (SRTs) of 20 and 40 days in order to determine the effect of SRT on both biological performance and dynamic membrane filtration characteristics. High COD removal efficiencies exceeding 99% were achieved during the operation at both SRTs. Higher filtration resistances were measured during the operation at SRT of 40 days in comparison to SRT of 20 days, applying a stable flux of 2.6 L/m(2) h. The higher filtration resistances coincided with lower extracellular polymeric substances concentration in the bulk sludge at SRT of 40 days, likely resulting in a decreased particle flocculation. Results showed that dynamic membrane technology achieved a stable and high quality permeate and AnDMBRs can be used as a reliable and satisfactory technology for treatment of high strength wastewaters.

  20. Migrainous vertigo and basilar migraine(Analyze the clinical symptoms of 9 migraine patients with vertigo)%偏头痛性眩晕与基底型偏头痛(附9例临床分析)

    Institute of Scientific and Technical Information of China (English)

    马维娅; 单希征; 孙勍; 李娜; 戴静; 彭新

    2012-01-01

    Objective By analysing the results of clinical and laboratory examinations in 9 migraine patients with vertigo or dizziness, we aimed to recognize the relationship between migraine and vertigo, and to improve the diagnosis and treatments of the patients. Methods Nine migraine patients with vertigo/dizziness were selected from our hospital. Besides the detailed questionnaire on the medical history, clinical and laboratory examinations, including neurological examination, vestibule functioning, hearing tests and head CT/MR1, were adopted in each patient, so as to exclude the cases caused by central and vestibule related vertigo. Results Among the 9 migraine patients with vertigo /dizziness, there were 2 cases of hasilar migraine, 3 cases of migraine without aura, and 6 cases of migrainous vertigo (MV, in which 2 migraine patients changed to MV). In the 6 MV patients, vertigo or dizziness occurred several seconds to one hour prior to the headache in 3 cases, post headache in 1 case and simultaneously with headache in 1 case. There was one migraine case, whose headache never occurred together with vertigo, called migraine equivalent. Conclusions MV is a special type of migraine syndrome associated with vertigo or dizziness due to basilar migraine. The diagnosis needs to be distinguished clearly from Meniere' s disease, benign paroxysmal positional vertigo, posterior circulation ischemia (PCI), etc.%目的 分析9例偏头痛伴眩晕/头晕患者的临床及实验室检查结果,探讨头痛与眩晕/头晕的关系,以利正确诊治.方法 作者医院收治的偏头痛伴眩晕/头晕患者9例,对所有患者均详细收集病史,并进行神经系统查体以及前庭功能、听力检查和头颅CT/MRI等实验室检查,以除外中枢性和耳源性眩晕.结果 9例偏头痛伴眩晕/头晕患者中,基底型偏头痛2例,无先兆偏头痛3例,偏头痛性眩晕( migrainous vertigo,MV)6例(其中2例为无先兆偏头痛发作数年后和50

  1. 33例基底动脉尖综合征临床及影像学分析%Clinical and Image Analyses of 33 Cases of Top Of The Basilar Syndrome (TOTBS)

    Institute of Scientific and Technical Information of China (English)

    陈茂玉; 林朋兴

    2015-01-01

    Objective To deepen the understanding of Top Of The Basilar Syndrome(TOTBS), improve its diagnosis and treatment, and reduce its incidence of misdiagnosis and therapeutic error by means of studying the etiology, pathogenesis, hazards, clinical manifestation, image features, therapy and prognosis of TOTBS.Methods Retrospectively analyze the 33 TOTBS patients treated in Ningde Mindong Hospital in 2013 to 2014.Results Followed by cardiac disease and diabetes, primary hypertension is the most common hazard (75.7%), most likely, pathogenesis of TOTBS is embolism, its clinical manifestations usually are dizziness and acute-onset caused by disturbance of consciousness, with symptoms of disturbance of consciousness, disorder of ocular movement, pupil changes and bilateral pyramidal sign in varying degrees. Manifestation of MRI Image Data The TOTBS patients suffer from cerebral infarction in more than one parts, such as in midbrain or thalamus as well as in epencephalon, temporal lobe and occipital lobe. primary hypertension is the most common hazard of TOTBS, MRI image manifestation can be counted as the reliable evidence of TOTBS diagnosis.Conclusion The clinical manifestation of TOTBS can be varied in symptoms, the death rate of TOTBS patients is quite high, and early diagnosis and proper therapies can greatly improve its prognosis.%目的:探讨基底动脉尖综合征(TOBS)的病因、发病机制、危险因素、临床表现、影像学特点、治疗及预后。以期加深对基底动脉尖综合征的了解,提高对基底动脉尖综合征的诊断与治疗,减少误诊误治的发生率。方法回顾性分析本院2013~2014年期间收治33例基底动脉尖综合征患者。结果原发性高血压是最常见危险因素(75.7%),其次为心脏疾病和2型糖尿病;主要发病机制为脑栓塞,临床表现常以眩晕及意识改变急性起病,主要表现为不同程度的意识障碍、眼球运动障碍、瞳孔对光反射及

  2. The intervention effect of diammonium glycyrrhizinate on the formation of basilar artery aneurysm in rabbits%甘草酸二铵干预兔基底动脉瘤形成的实验研究

    Institute of Scientific and Technical Information of China (English)

    桂铮; 汪子文; 张鹏飞; 赵文可; 于耀宇

    2016-01-01

    Objective To explore the mechanism and intervention effects of diammonium glycyrrhizinate (DG) on the formation of intracranial aneurysm (IA) in rabbits. Methods Forty New Zealand rabbits were randomly divided into four groups: control group, IA group, normal saline (NS) group and DG group, 10 rabbits for each group. Except for the control group, rabbits in other three groups were operated with bilateral common carotid artery ligation to produce basilar artery aneurysm formation model. DG group was injected intravenously with DG[20 mg/(kg·d)]from the first day to the seventh day after operation, NS group was given same volume of normal saline, while IA group was injected nothing. The expressions of NF-κB and MMP-9 were detected by immunohistochemical staining, whileα-SMA was stained with immunofluorescence. Results The expressions of NF-κB and MMP-9 were significantly higher in IA group and NS group than those of control group, whileα-SMA expression was significantly lower than that of control group (P0.05). The expressions of NF-κB and MMP-9 were significantly lower in DG group than those of IA group and NS group (P<0.05). The expression of α-SMA was significantly higher in DG group than that of IA group and NS group (P<0.05). Conclusion DG can downregulate the expression levels of NF-κB and MMP-9 in intracranial aneurysm, suppress inflammatory in artery wall and reduce the pathological changes and have intervention effect on intracranial aneurysm formation.%目的:探讨甘草酸二铵(DG)干预兔基底动脉瘤发生的作用机制。方法新西兰白兔40只,按照随机数字表法分为对照组、动脉瘤(IA)组、生理盐水(NS)组、DG组,每组10只。其中对照组不做任何处理,其余各组结扎双侧颈总动脉建立基底动脉瘤形成模型。在造模后的第1~7天,IA组不做处理,DG组给予DG[20 mg/(kg·d)]静脉注射,NS组注入等剂量生理盐水。使用免疫组化染色方法检测基

  3. Electronic polymers in lipid membranes.

    Science.gov (United States)

    Johansson, Patrik K; Jullesson, David; Elfwing, Anders; Liin, Sara I; Musumeci, Chiara; Zeglio, Erica; Elinder, Fredrik; Solin, Niclas; Inganäs, Olle

    2015-06-10

    Electrical interfaces between biological cells and man-made electrical devices exist in many forms, but it remains a challenge to bridge the different mechanical and chemical environments of electronic conductors (metals, semiconductors) and biosystems. Here we demonstrate soft electrical interfaces, by integrating the metallic polymer PEDOT-S into lipid membranes. By preparing complexes between alkyl-ammonium salts and PEDOT-S we were able to integrate PEDOT-S into both liposomes and in lipid bilayers on solid surfaces. This is a step towards efficient electronic conduction within lipid membranes. We also demonstrate that the PEDOT-S@alkyl-ammonium:lipid hybrid structures created in this work affect ion channels in the membrane of Xenopus oocytes, which shows the possibility to access and control cell membrane structures with conductive polyelectrolytes.

  4. Robust mixed conducting membrane structure

    DEFF Research Database (Denmark)

    2010-01-01

    The present invention provides a membrane structure, comprising in said order a first electronically conducting layer, an ionically conducting layer, and a second electronically conducting layer, characterized in that the first and second electronically conducting layers are internally short circ...

  5. Membrane solutions to Horava gravity

    CERN Document Server

    Argüelles, Carlos R

    2010-01-01

    We investigated purely gravitational membrane solutions to Ho\\v rava nonrelativistic theory of gravity with detailed balance in $3+1$ dimensions. We find that for arbitrary values of the running parameter $\\lambda>1/3$ two branches of membrane solutions exist, and that in the special case $\\lambda=1$ one of them is degenerate, the lapse function being undetermined. For negative values of the cosmological constant, the solution contains a single membrane sitting at the center of a space, which extends infinitely in the transverse direction approaching a Lifshitz metric. For positive values of the cosmological constant, the solution represents a space that is bounded in the transverse direction, with two parallel membranes hidden behind event horizons sitting at each of the boundaries.

  6. Alphavirus Entry and Membrane Fusion

    Directory of Open Access Journals (Sweden)

    Margaret Kielian

    2010-03-01

    Full Text Available The study of enveloped animal viruses has greatly advanced our understanding of the general properties of membrane fusion and of the specific pathways that viruses use to infect the host cell. The membrane fusion proteins of the alphaviruses and flaviviruses have many similarities in structure and function. As reviewed here, alphaviruses use receptor-mediated endocytic uptake and low pH-triggered membrane fusion to deliver their RNA genomes into the cytoplasm. Recent advances in understanding the biochemistry and structure of the alphavirus membrane fusion protein provide a clearer picture of this fusion reaction, including the protein’s conformational changes during fusion and the identification of key domains. These insights into the alphavirus fusion mechanism suggest new areas for experimental investigation and potential inhibitor strategies for anti-viral therapy.

  7. Composite solid polymer electrolyte membranes

    Energy Technology Data Exchange (ETDEWEB)

    Formato, Richard M. (Shrewsbury, MA); Kovar, Robert F. (Wrentham, MA); Osenar, Paul (Watertown, MA); Landrau, Nelson (Marlborough, MA); Rubin, Leslie S. (Newton, MA)

    2001-06-19

    The present invention relates to composite solid polymer electrolyte membranes (SPEMs) which include a porous polymer substrate interpenetrated with an ion-conducting material. SPEMs of the present invention are useful in electrochemical applications, including fuel cells and electrodialysis.

  8. Aniseikonia associated with epiretinal membranes

    OpenAIRE

    Ugarte, M.; Williamson, T H

    2005-01-01

    Aims: To determine whether the computerised version of the new aniseikonia test (NAT) is a valid, reliable method to measure aniseikonia and establish whether aniseikonia occurs in patients with epiretinal membranes (ERM) with preserved good visual acuity.

  9. Geometry of Membrane Sigma Models

    CERN Document Server

    Vysoky, Jan

    2015-01-01

    String theory still remains one of the promising candidates for a unification of the theory of gravity and quantum field theory. One of its essential parts is relativistic description of moving multi-dimensional objects called membranes (or p-branes) in a curved spacetime. On the classical field theory level, they are described by an action functional extremalising the volume of a manifold swept by a propagating membrane. This and related field theories are collectively called membrane sigma models. Differential geometry is an important mathematical tool in the study of string theory. It turns out that string and membrane backgrounds can be conveniently described using objects defined on a direct sum of tangent and cotangent bundles of the spacetime manifold. Mathematical field studying such object is called generalized geometry. Its integral part is the theory of Leibniz algebroids, vector bundles with a Leibniz algebra bracket on its module of smooth sections. Special cases of Leibniz algebroids are better ...

  10. Mobility in geometrically confined membranes.

    Science.gov (United States)

    Domanov, Yegor A; Aimon, Sophie; Toombes, Gilman E S; Renner, Marianne; Quemeneur, François; Triller, Antoine; Turner, Matthew S; Bassereau, Patricia

    2011-08-02

    Lipid and protein lateral mobility is essential for biological function. Our theoretical understanding of this mobility can be traced to the seminal work of Saffman and Delbrück, who predicted a logarithmic dependence of the protein diffusion coefficient (i) on the inverse of the size of the protein and (ii) on the "membrane size" for membranes of finite size [Saffman P, Delbrück M (1975) Proc Natl Acad Sci USA 72:3111-3113]. Although the experimental proof of the first prediction is a matter of debate, the second has not previously been thought to be experimentally accessible. Here, we construct just such a geometrically confined membrane by forming lipid bilayer nanotubes of controlled radii connected to giant liposomes. We followed the diffusion of individual molecules in the tubular membrane using single particle tracking of quantum dots coupled to lipids or voltage-gated potassium channels KvAP, while changing the membrane tube radius from approximately 250 to 10 nm. We found that both lipid and protein diffusion was slower in tubular membranes with smaller radii. The protein diffusion coefficient decreased as much as 5-fold compared to diffusion on the effectively flat membrane of the giant liposomes. Both lipid and protein diffusion data are consistent with the predictions of a hydrodynamic theory that extends the work of Saffman and Delbrück to cylindrical geometries. This study therefore provides strong experimental support for the ubiquitous Saffman-Delbrück theory and elucidates the role of membrane geometry and size in regulating lateral diffusion.

  11. Membranes in Lithium Ion Batteries

    Directory of Open Access Journals (Sweden)

    Junbo Hou

    2012-07-01

    Full Text Available Lithium ion batteries have proven themselves the main choice of power sources for portable electronics. Besides consumer electronics, lithium ion batteries are also growing in popularity for military, electric vehicle, and aerospace applications. The present review attempts to summarize the knowledge about some selected membranes in lithium ion batteries. Based on the type of electrolyte used, literature concerning ceramic-glass and polymer solid ion conductors, microporous filter type separators and polymer gel based membranes is reviewed.

  12. Membranes in lithium ion batteries.

    Science.gov (United States)

    Yang, Min; Hou, Junbo

    2012-07-04

    Lithium ion batteries have proven themselves the main choice of power sources for portable electronics. Besides consumer electronics, lithium ion batteries are also growing in popularity for military, electric vehicle, and aerospace applications. The present review attempts to summarize the knowledge about some selected membranes in lithium ion batteries. Based on the type of electrolyte used, literature concerning ceramic-glass and polymer solid ion conductors, microporous filter type separators and polymer gel based membranes is reviewed.

  13. 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...

  14. Sulfonated Polyetherimide and Its Membranes

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    Polyetherimide (PEI) was sulfonated by chlorosulfonic acid for the first time. The sulfonated products were characterized by FT-IR, DSC, ion exchange capacity and water sorption measurement. The hydrophilicity of PEI was improved by the sulfonation. The PEI was blended with the sodium salt form of sulfonated PEI (SPEI) to prepare microporous membranes. The morphologies of the membranes were studied with Scanning Electron Microscope (SEM).

  15. Establishment of a three-dimensional finite element model of basilar invagination and occipitalization of atlas on HyperMesh%基于HyperMesh建立颅底陷入合并寰枕融合畸形的三维有限元模型

    Institute of Scientific and Technical Information of China (English)

    梁韬; 孟春玲; 尹一恒; 刘广伟; 余新光

    2016-01-01

    Objective To explore how to establish a three-dimensional finite element model of basilar invagination and occipitalization of atlas. Methods The CT data of craniovertebral junction in a typical patient with basilar invagination and occipitalization of atlas was collected. Mimics software was used to edit CT pictures and generate the three-dimensional geometric model of atlanto-occipital fusion corpus and axis surface. Then point cloud was exported. Reverse engineering software of Imageware was used to process point cloud data and generate three-dimensional curved surface. The surface model was blocked first and then meshed by Hypermesh software. The mesh model was finally exported by the method of mix-meshing in tetrahedrons and hexahedrons. The mesh model was imported into finite element software of Abaqus. Finite element model was established by adding ligaments, assigning material, defining contact and defining boundary. Results The finite element model of basilar invagination and occipitalization of atlas contained 474,162 elements and 235,524 notes with good geometric similarity. Conclusion The three-dimensional finite element model of basilar invagination and occipitalization of atlas provides the basis for the research on craniovertebral junction malformation, and it can be used for reference of establishment of finite element model in upper cervical spine malformation.%目的:探讨建立颅底陷入合并寰枕融合畸形的三维有限元模型的方法。方法采集1例颅底陷入合并寰枕融合畸形患者的颅颈交界区的CT薄层扫描数据,利用Mimics软件对CT数据进行处理,生成三维几何表面模型,并导出点云;采用逆向工程软件Imageware处理点云数据,生成三维曲面;采用四面体与六面体混合分网的思路,利用HyperMesh对曲面模型先分块再分网,最后导出网格模型;将网格模型导入有限元软件Abaqus,进行韧带添加、材料赋值、接触定义、边界

  16. Membrane fusion during poxvirus entry.

    Science.gov (United States)

    Moss, Bernard

    2016-12-01

    Poxviruses comprise a large family of enveloped DNA viruses that infect vertebrates and invertebrates. Poxviruses, unlike most DNA viruses, replicate in the cytoplasm and encode enzymes and other proteins that enable entry, gene expression, genome replication, virion assembly and resistance to host defenses. Entry of vaccinia virus, the prototype member of the family, can occur at the plasma membrane or following endocytosis. Whereas many viruses encode one or two proteins for attachment and membrane fusion, vaccinia virus encodes four proteins for attachment and eleven more for membrane fusion and core entry. The entry-fusion proteins are conserved in all poxviruses and form a complex, known as the Entry Fusion Complex (EFC), which is embedded in the membrane of the mature virion. An additional membrane that encloses the mature virion and is discarded prior to entry is present on an extracellular form of the virus. The EFC is held together by multiple interactions that depend on nine of the eleven proteins. The entry process can be divided into attachment, hemifusion and core entry. All eleven EFC proteins are required for core entry and at least eight for hemifusion. To mediate fusion the virus particle is activated by low pH, which removes one or more fusion repressors that interact with EFC components. Additional EFC-interacting fusion repressors insert into cell membranes and prevent secondary infection. The absence of detailed structural information, except for two attachment proteins and one EFC protein, is delaying efforts to determine the fusion mechanism.

  17. Tethered bimolecular lipid membranes - A novel model membrane platform

    Energy Technology Data Exchange (ETDEWEB)

    Knoll, Wolfgang; Koeper, Ingo; Naumann, Renate; Sinner, Eva-Kathrin [Max Planck Institute for Polymer Research, Ackermannweg 10, 55128 Mainz (Germany)

    2008-10-01

    This contribution summarizes some of our efforts in designing, synthesizing, assembling, and characterizing functional tethered bimolecular lipid membranes (tBLMs) as a novel platform for biophysical studies of and with artificial membranes or for sensor development employing, e.g., membrane integral receptor proteins. Chemical coupling schemes based on thiol groups for Au substrates or silanes used in the case of oxide surfaces allow for the covalent and, hence, chemically and mechanically robust attachment of anchor lipids to the solid support, stabilizing the proximal layer of a tethered membrane on the transducer surface. Surface plasmon optics, the quartz crystal microbalance, fluorescence- and IR spectroscopies, and electrochemical techniques are used to characterize the build-up of these complex supramolecular interfacial architectures. We demonstrate, in particular, that bilayers with a specific electrical resistance of better than 10 M{omega} cm{sup 2} can be achieved routinely with this approach. The functionalization of the lipid membranes by the incorporation of peptides is demonstrated for the carrier valinomycin which shows in our tBLMs the expected discrimination by four orders of magnitude between the translocation of K{sup +}- and Na{sup +}-ions across the hydrophobic barrier. For the synthetic channel-forming peptide M2 the high electrical resistance of the bilayer with the correspondingly low background current allows for the recording of even single channel current fluctuations. From the many membrane proteins that we reconstituted so far we describe results obtained with the redox-protein cytochrome c oxidase. Here, we also use a genetically modified mutant with a His-tag at either the C- or the N-terminus for the oriented attachment of the protein via the NTA/Ni{sup 2+} approach. With this strategy, we not only can control the density of the immobilized functional units, we introduce a completely new and alternative concept for the

  18. Hydrogen purifier module with membrane support

    Science.gov (United States)

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

    2012-07-24

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

  19. Nonadhesive acoustic membranes based on polyimide

    Directory of Open Access Journals (Sweden)

    Vorob'ev A.V.

    2014-02-01

    Full Text Available The paper presents a comparison of technical characteristics of acoustic membranes with an adhesive layer and nonadhesive membranes. The authors present the manufacturing technology for acoustic membranes based on aluminum-polyimide film dielectrics and analyze the advantages of such membranes in comparison to other sound emitters.

  20. Ninth International Workshop on Plant Membrane Biology

    Energy Technology Data Exchange (ETDEWEB)

    1993-12-31

    This report is a compilation of abstracts from papers which were discussed at a workshop on plant membrane biology. Topics include: plasma membrane ATP-ases; plant-environment interactions, membrane receptors; signal transduction; ion channel physiology; biophysics and molecular biology; vaculor H+ pumps; sugar carriers; membrane transport; and cellular structure and function.

  1. The Molecules of the Cell Membrane.

    Science.gov (United States)

    Bretscher, Mark S.

    1985-01-01

    Cell membrane molecules form a simple, two-dimensional liquid controlling what enters and leaves the cell. Discusses cell membrane molecular architecture, plasma membranes, epithelial cells, cycles of endocytosis and exocytosis, and other topics. Indicates that some cells internalize, then recycle, membrane area equivalent to their entire surface…

  2. Wind effects on a stretched membrane heliostat

    Energy Technology Data Exchange (ETDEWEB)

    Bienkiewicz, B. (Colorado State Univ., Fort Collins, CO (United States). Dept. of Civil Engineering)

    1993-08-01

    Wind effects on stretched membrane heliostat were investigated in a boundary layer wind tunnel. The membrane response was measured at stow and representative operational conditions. It was found that both at the stow and operational conditions the mean response was much higher than the rms response. At stow conditions the largest response occurred near the leading edge of the membrane, while the rms response was the largest at the membrane center point. For the operational conditions, the largest mean and rms responses were found at the membrane centerpoint. The membrane response was significantly reduced by the membrane focusing induced through the internal underpressure.

  3. 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.

  4. 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.

  5. Self-Deployable Membrane Structures

    Science.gov (United States)

    Sokolowski, Witold M.; Willis, Paul B.; Tan, Seng C.

    2010-01-01

    Currently existing approaches for deployment of large, ultra-lightweight gossamer structures in space rely typically upon electromechanical mechanisms and mechanically expandable or inflatable booms for deployment and to maintain them in a fully deployed, operational configuration. These support structures, with the associated deployment mechanisms, launch restraints, inflation systems, and controls, can comprise more than 90 percent of the total mass budget. In addition, they significantly increase the stowage volume, cost, and complexity. A CHEM (cold hibernated elastic memory) membrane structure without any deployable mechanism and support booms/structure is deployed by using shape memory and elastic recovery. The use of CHEM micro-foams reinforced with carbon nanotubes is considered for thin-membrane structure applications. In this advanced structural concept, the CHEM membrane structure is warmed up to allow packaging and stowing prior to launch, and then cooled to induce hibernation of the internal restoring forces. In space, the membrane remembers its original shape and size when warmed up. After the internal restoring forces deploy the structure, it is then cooled to achieve rigidization. For this type of structure, the solar radiation could be utilized as the heat energy used for deployment and space ambient temperature for rigidization. The overall simplicity of the CHEM self-deployable membrane is one of its greatest assets. In present approaches to space-deployable structures, the stow age and deployment are difficult and challenging, and introduce a significant risk, heavy mass, and high cost. Simple procedures provided by CHEM membrane greatly simplify the overall end-to-end process for designing, fabricating, deploying, and rigidizing large structures. The CHEM membrane avoids the complexities associated with other methods for deploying and rigidizing structures by eliminating deployable booms, deployment mechanisms, and inflation and control systems

  6. Liquid membrane purification of biogas

    Energy Technology Data Exchange (ETDEWEB)

    Majumdar, S.; Guha, A.K.; Lee, Y.T.; Papadopoulos, T.; Khare, S. (Stevens Inst. of Tech., Hoboken, NJ (United States). Dept. of Chemistry and Chemical Engineering)

    1991-03-01

    Conventional gas purification technologies are highly energy intensive. They are not suitable for economic removal of CO{sub 2} from methane obtained in biogas due to the small scale of gas production. Membrane separation techniques on the other hand are ideally suited for low gas production rate applications due to their modular nature. Although liquid membranes possess a high species permeability and selectivity, they have not been used for industrial applications due to the problems of membrane stability, membrane flooding and poor operational flexibility, etc. A new hollow-fiber-contained liquid membrane (HFCLM) technique has been developed recently. This technique overcomes the shortcomings of the traditional immobilized liquid membrane technology. A new technique uses two sets of hydrophobic, microporous hollow fine fibers, packed tightly in a permeator shell. The inter-fiber space is filled with an aqueous liquid acting as the membrane. The feed gas mixture is separated by selective permeation of a species through the liquid from one fiber set to the other. The second fiber set carries a sweep stream, gas or liquid, or simply the permeated gas stream. The objectives (which were met) of the present investigation were as follows. To study the selective removal of CO{sub 2} from a model biogas mixture containing 40% CO{sub 2} (the rest being N{sub 2} or CH{sub 4}) using a HFCLM permeator under various operating modes that include sweep gas, sweep liquid, vacuum and conventional permeation; to develop a mathematical model for each mode of operation; to build a large-scale purification loop and large-scale permeators for model biogas separation and to show stable performance over a period of one month.

  7. Large pore size polyacrylonitrile membrane for ultrafiltration

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    The effects of the components of solution for membrane casting and preparation conditions on the membrane perrormances are studied in this paper. Polyacrylonitrile(PAN) was used as polymer and DMAC as solvent. The ultrafiltration (UF) membranes whose cut-off of molecular weight is 150000 and flux of pure water reaches 150-200 ml/(cm2 ·h) were prepared by selecting proper components of solution for membrane casting and membrane preparation conditions.

  8. Immersed surfaces and membranes transformations

    Science.gov (United States)

    Kats, E. I.; Monastyrsky, M. I.

    2015-06-01

    Physical and biological observation methods provide a variety of bilayer membranes’ shapes and their transformations. Besides, the topological and geometrical methods allow us to deduce a classification of all possible membrane surfaces. This double-sided approach leads to a deeper insight into membranes properties. Our goal is to apply an appropriate mathematical technique for classifying vesicles (closed surfaces in mathematical terminology) and for their transformation ways. The problem turned out to be an intricate one, and to our knowledge no mathematical techniques have been applied to its solution. We find that all vesicles can be decomposed in a small number of universality classes generated by a few ‘bricks’: a torus, a screwed torus, and the real projective plane. We consider several ways of transforming membrane surfaces, bearing in mind that they possess an additional extremal property. Our method exploits different constructions of minimal surfaces in S3. We estimate energetic barrier for transformation of minimal membrane surfaces using the so-called doubling procedure. This problem is far from being a pure theoretical exercise. For instance, almost all cells’ biological functions, or tumor progression, are accompanied by apparently singular cell membrane transformations.

  9. Cytotoxicity of Mycoplasma pneumoniae Membranes

    Science.gov (United States)

    Gabridge, Michael G.; Johnson, Cynthia K.; Cameron, Alexander M.

    1974-01-01

    Organ cultures of adult hamster trachea were used to evaluate the cytotoxic potential of cell fractions of Mycoplasma pneumoniae. Cytoplasm was essentially devoid of activity, whereas viable cells and membrane preparations, at a level of 25 μg of protein per ml, induced necrosis. Damage, as revealed by light and electron microscopy, included ciliostasis, vacuolization, loss of ciliated respiratory epithelial cells, disorganization, and a loss of polarity. Dose response data indicated that the speed and degree of cytotoxicity was directly related to the concentration of membranes. Doses of 30 to 60 μg of protein per ml could reduce relative ciliary activity to 20% of the control level within 4 days. Membranes prepared after freeze-thaw lysis of cells were almost twice as active as those isolated after a combination of osmotic and sonic shock. Membranes of M. fermentans were inactive, though both the FH and M129 strains of M. pneumoniae were toxic. These data indicate that the toxic factor responsible for M. pneumoniae may be located in the cell membrane. Images PMID:16558100

  10. Effective interactions between fluid membranes

    CERN Document Server

    Lu, Bing-Sui

    2016-01-01

    A self-consistent theory is proposed for the general problem of interacting undulating fluid membranes subject to the constraint that they do not interpenetrate. We implement the steric constraint via an exact functional integral representation, and through the use of a saddle-point approximation transform it into a novel effective steric potential. The steric potential is found to consist of two contributions: one generated by zero mode fluctuations of the membranes, and the other by thermal bending fluctuations. For membranes of cross-sectional area $S$, we find that the bending fluctuation part scales with the inter-membrane separation $d$ as $d^{-2}$ for $d \\ll \\sqrt{S}$, but crosses over to $d^{-4}$ scaling for $d \\gg \\sqrt{S}$, whereas the zero mode part of the steric potential always scales as $d^{-2}$. For membranes interacting exclusively via the steric potential, we obtain closed-form expressions for the effective interaction potential and for the rms undulation amplitude $\\sigma$, which becomes sma...

  11. Electroporation of heterogeneous lipid membranes.

    Science.gov (United States)

    Reigada, Ramon

    2014-03-01

    Electroporation is the basis for the transfection of genetic material and for drug delivery to cells, including electrochemotherapy for cancer. By means of molecular dynamics many aspects of membrane electroporation have been unveiled at the molecular detail in simple, homogeneous, lipid bilayers. However, the correspondence of these findings \\with the process happening in cell membranes requires, at least, the consideration of laterally structured membranes. Here, I present a systematic molecular dynamics study of bilayers composed of different liquid-ordered and liquid-disordered lipid phases subjected to a transversal electric field. The simulations reveal two significant results. First, the electric field mainly affects the properties of the disordered phases, so that electroporation takes place in these membrane regions. Second, the smaller the disordered domains are, the faster they become electroporated. These findings may have a relevant significance in the experimental application of cell electroporation in vivo since it implies that electro-induced and pore-mediated transport processes occur in particularly small disordered domains of the plasma membrane, thus locally affecting only specific regions of the cell.

  12. 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.

  13. Stabilizing membrane domains antagonizes anesthesia

    CERN Document Server

    Machta, Benjamin B; Nouri, Mariam; McCarthy, Nicola L C; Gray, Erin M; Miller, Ann L; Brooks, Nicholas J; Veatch, Sarah L

    2016-01-01

    Diverse molecules induce general anesthesia with potency strongly correlated both with their hydrophobicity and their effects on certain ion channels. We recently observed that several anesthetics inhibit heterogeneity in plasma membrane derived vesicles by lowering the critical temperature ($T_c$) for phase separation. Here we exploit conditions that stabilize membrane heterogeneity to test the correlation between the anesthetic potency of n-alcohols and effects on $T_c$. First we show that hexadecanol acts oppositely to anesthetics on membrane mixing and antagonizes ethanol induced anesthesia in a tadpole behavioral assay. Second, we show that two previously described `intoxication reversers' raise $T_c$ in vesicles and counter ethanol's effects in vesicles, mimicking the findings of previous electrophysiological measurements. Third, we find that hydrostatic pressure, long known to reverse anesthesia, also raises $T_c$ in vesicles with a magnitude that counters the effect of an anesthetic at relevant concen...

  14. 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.

  15. 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

  16. 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.

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

    OpenAIRE

    Balster, Jörg Henning

    2006-01-01

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

  18. Dielectric breakdown of cell membranes.

    Science.gov (United States)

    Zimmermann, U; Pilwat, G; Riemann, F

    1974-11-01

    With human and bovine red blood cells and Escherichia coli B, dielectric breakdown of cell membranes could be demonstrated using a Coulter Counter (AEG-Telefunken, Ulm, West Germany) with a hydrodynamic focusing orifice. In making measurements of the size distributions of red blood cells and bacteria versus increasing electric field strength and plotting the pulse heights versus the electric field strength, a sharp bend in the otherwise linear curve is observed due to the dielectric breakdown of the membranes. Solution of Laplace's equation for the electric field generated yields a value of about 1.6 V for the membrane potential at which dielectric breakdown occurs with modal volumes of red blood cells and bacteria. The same value is also calculated for red blood cells by applying the capacitor spring model of Crowley (1973. Biophys. J. 13:711). The corresponding electric field strength generated in the membrane at breakdown is of the order of 4 . 10(6) V/cm and, therefore, comparable with the breakdown voltages for bilayers of most oils. The critical detector voltage for breakdown depends on the volume of the cells. The volume-dependence predicted by Laplace theory with the assumption that the potential generated across the membrane is independent of volume, could be verified experimentally. Due to dielectric breakdown the red blood cells lose hemoglobin completely. This phenomenon was used to study dielectric breakdown of red blood cells in a homogeneous electric field between two flat platinum electrodes. The electric field was applied by discharging a high voltage storage capacitor via a spark gap. The calculated value of the membrane potential generated to produce dielectric breakdown in the homogeneous field is of the same order as found by means of the Coulter Counter. This indicates that mechanical rupture of the red blood cells by the hydrodynamic forces in the orifice of the Coulter Counter could also be excluded as a hemolysing mechanism. The detector

  19. Sheet Membrane Spacesuit Water Membrane Evaporator Thermal Test

    Science.gov (United States)

    Trevino, Luis A.; Bue, Grant C.

    2009-01-01

    For future lunar extravehicular activities (EVA), one method under consideration for rejecting crew and electronics heat involves evaporating water through a hydrophobic, porous Teflon(Registered Trademark) membrane. A Spacesuit Water Membrane Evaporator (SWME) prototype using this membrane was successfully tested by Ungar and Thomas (2001) with predicted performance matching test data well. The above referenced work laid the foundation for the design of a compact sheet membrane SWME development unit for use in the Constellation System Spacesuit Element Portable Life Support System (Vogel and et. al., ICES 2008). Major design objectives included minimizing mass, volume, and manufacturing complexity while rejecting a minimum of 810 watts of heat from water flowing through the SWME at 91 kg/hr with an inlet temperature of 291K. The design meeting these objectives consisted of three concentric cylindrical water channels interlaced with four water vapor channels. Two units were manufactured for the purpose of investigating manufacturing techniques and performing thermal testing. The extensive thermal test measured SWME heat rejection as a function of water inlet temperatures, water flow-rates, water absolute pressures, water impurities, and water vapor back-pressures. This paper presents the test results and subsequent analysis, which includes a comparison of SWME heat rejection measurements to pretest predictions. In addition, test measurements were taken such that an analysis of the commercial-off-the-shelf vapor pressure control valve could be performed.

  20. Membrane tubulation by elongated and patchy nanoparticles

    CERN Document Server

    Raatz, Michael

    2016-01-01

    Advances in nanotechnology lead to an increasing interest in how nanoparticles interact with biomembranes. Nanoparticles are wrapped spontaneously by biomembranes if the adhesive interactions between the particles and membranes compensate for the cost of membrane bending. In the last years, the cooperative wrapping of spherical nanoparticles in membrane tubules has been observed in experiments and simulations. For spherical nanoparticles, the stability of the particle-filled membrane tubules strongly depends on the range of the adhesive particle-membrane interactions. In this article, we show via modeling and energy minimization that elongated and patchy particles are wrapped cooperatively in membrane tubules that are highly stable for all ranges of the particle-membrane interactions, compared to individual wrapping of the particles. The cooperative wrapping of linear chains of elongated or patchy particles in membrane tubules may thus provide an efficient route to induce membrane tubulation, or to store such...

  1. Membrane interaction of retroviral Gag proteins

    Directory of Open Access Journals (Sweden)

    Robert Alfred Dick

    2014-04-01

    Full Text Available Assembly of an infectious retroviral particle relies on multimerization of the Gag polyprotein at the inner leaflet of the plasma membrane. The three domains of Gag common to all retroviruses-- MA, CA, and NC-- provide the signals for membrane binding, assembly, and viral RNA packaging, respectively. These signals do not function independently of one another. For example, Gag multimerization enhances membrane binding and is more efficient when NC is interacting with RNA. MA binding to the plasma membrane is governed by several principles, including electrostatics, recognition of specific lipid head groups, hydrophobic interactions, and membrane order. HIV-1 uses many of these principles while Rous sarcoma virus (RSV appears to use fewer. This review describes the principles that govern Gag interactions with membranes, focusing on RSV and HIV-1 Gag. The review also defines lipid and membrane behavior, and discusses the complexities in determining how lipid and membrane behavior impact Gag membrane binding.

  2. Bioinspired Multifunctional Membrane for Aquatic Micropollutants Removal

    DEFF Research Database (Denmark)

    Cao, Xiaotong; Luo, Jianquan; Woodley, John;

    2016-01-01

    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...

  3. SolitaireTM支架取栓治疗急性基底动脉闭塞研究%Mechanical Thrombectomy with the SolitaireTM Device in Acute Basilar Artery Occlusion

    Institute of Scientific and Technical Information of China (English)

    高峰; 孙瑄; 莫大鹏; 马宁; 刘恋; 霍晓川; 缪中荣

    2015-01-01

    Objective To evaluate the efifcacy and safety of mechanical thrombectomy with the SolitaireTM device in revascularization of patients with acute basilar artery occlusion (ABAO) and to identify its predictive factors for clinical outcome. Methods Thirty patients with acute ischemic stroke attributable to ABAO treated with the SolitaireTM device in our center were retrospectively studied. Recanalization rates after stent Retrieval were determined and the clinical outcome and mortality rate were assessed 90 days after treatment. Predictive factors for clinical outcome were analyzed. Results The mean age of the patients was (58.6±8.4) years, the median prethrombectomy National Institutes of Health Stroke Scale score was 25.5 (21.3, 29.5), the median Glasgow Coma Scale (GCS) score was 8 (6.0, 9.8) and the mean modiifed Rankin Scale (mRS) score was 5 (5.0, 5.0). Successful recanalization (Thrombolysis in Cerebral Ischemia Scale, TICI 3 or 2b) was achieved in 28 patients (93.3%). Six symptomatic intracranial hemorrhages occurred after procedure. A favorable outcome, defined as a mRS of 0~2, was observed in 30.0% of patients (9/30). Overall mortality rate was 30.0% (9/30). In the univariate analysis, patients with coma (P=0.014) and a higher mRS (mRS>2, P=0.020) on admission was signiifcantly associated with a poor outcome. Conclusion Mechanical thrombectomy with the SolitaireTM device can rapidly and effectively contribute to a high rate of recanalization and improve functional outcome in patients with ABAO.%目的:评估急性基底动脉闭塞患者使用SolitaireTM支架机械取栓的有效性和安全性,分析其临床预后的影响因素。方法回顾性分析本中心连续入组的30例急性基底动脉闭塞患者,均使用SolitaireTM支架设备进行机械取栓治疗分析支架,分析取栓治疗的再通率及并发症,评估治疗90 d临床预后,分析影响临床预后的因素。结果30例患者均顺利完成机械取栓手

  4. Selection of indications and surgical treatment of basilar invagination with atlantoaxial dislocation%脱位型颅底凹陷症的手术适应证选择及外科治疗

    Institute of Scientific and Technical Information of China (English)

    徐韬; 甫拉提·买买提; 郭海龙; 买尔旦·买买提; 盛军; 梁卫东; 邓强; 荀传辉; 张健

    2015-01-01

    目的 探讨脱位型颅底凹陷症患者手术适应证的选择及外科治疗的意义.方法 回顾性分析2000年7月至2013年12月新疆医科大学第一附属医院脊柱外科共收治脱位型颅底凹陷症患者21例,其中男10例,女11例;平均年龄36.4(7 ~59)岁.记录其临床症状和体征,拍摄颈椎正、侧及动力位X线片并行MRI和CT扫描.所有患者均采取手术治疗.记录术前、后及末次随访时Oswestry功能障碍指数(ODI)评分、日本骨科学会评分(JOA),术后及随访时通过X线片、MRI或CT观察减压、固定及植骨融合情况.结果 本组牵引复位行后路固定融合2例,后路松解固定融合3例,联合前后路16例,寰枢椎固定2例,枕颈固定19例,术后均获充分复位和减压.平均手术时间200(110~235) min.平均出血量230 (150~450) ml.除2例死亡外,19例获随访,平均随访时间21.6(13 ~42)个月.患者术后JOA评分(14.1±0.5)分及末次随访评分(16.2±0.7)分较术前(7.8±1.3)分显著降低(P<0.05),术后NDI评分(28.2±9.6)分及末次随访评分(22.7±7.4)分较术前(65.7±11.2)分显著降低(P<0.05),术后及末次随访JOA、NDI评分差异无统计学意(P>0.05).植骨于术后平均11.5(9 ~20)个月融合.围手术期并发症6例,包括感染2例,脑脊液漏2例,呼吸功能障碍、颚裂各1例.结论 脱位型颅底凹陷症可选择前路、后路或联合前后路手术治疗.术前认真评估、合理的适应证选择及减少围手术期各种并发症是保证手术成功的关键.%Objective To evaluate the indications and effect of surgical treatment of basilar invagination (BI) with atlantoaxial dislocation (AAD) on the basis of retrospective analysis of the clinical and imaging data of patients.Methods Consecutive 21 patients with BI and AAD were surgically treated in Department of Spinal Surgery,The First Affiliated Hospital of Xinjiang Medical University from July 2000 to December 2013.There were 10 males and 11

  5. 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)

  6. 3D Membrane Imaging and Porosity Visualization

    KAUST Repository

    Sundaramoorthi, Ganesh

    2016-03-03

    Ultrafiltration asymmetric porous membranes were imaged by two microscopy methods, which allow 3D reconstruction: Focused Ion Beam and Serial Block Face Scanning Electron Microscopy. A new algorithm was proposed to evaluate porosity and average pore size in different layers orthogonal and parallel to the membrane surface. The 3D-reconstruction enabled additionally the visualization of pore interconnectivity in different parts of the membrane. The method was demonstrated for a block copolymer porous membrane and can be extended to other membranes with application in ultrafiltration, supports for forward osmosis, etc, offering a complete view of the transport paths in the membrane.

  7. Solvent-resistant microporous polymide membranes

    Science.gov (United States)

    Miller, Warren K.; McCray, Scott B.; Friesen, Dwayne T.

    1998-01-01

    An asymmetric microporous membrane with exceptional solvent resistance and highly desirable permeability is disclosed. The membrane is made by a solution-casting or solution-spinning process from a copolyamic acid comprising the condensation reaction product in a solvent of at least three reactants selected from certain diamines and dianhydrides and post-treated to imidize and in some cases cross-link the copolyamic acid. The membrane is useful as an uncoated membrane for ultrafiltration, microfiltration, and membrane contactor applications, or may be used as a support for a permselective coating to form a composite membrane useful in gas separations, reverse osmosis, nanofiltration, pervaporation, or vapor permeation.

  8. Graphene-based membranes: status and prospects.

    Science.gov (United States)

    Yoon, Hee Wook; Cho, Young Hoon; Park, Ho Bum

    2016-02-13

    Recently, graphene-based membranes have been extensively studied, represented by two distinct research directions: (i) creating pores in graphene basal plane and (ii) engineering nanochannels in graphene layers. Most simulation results predict that porous graphene membranes can be much more selective and permeable than current existing membranes, also evidenced by some experimental results for gas separation and desalination. In addition, graphene oxide has been widely investigated in layered membranes with two-dimensional nanochannels, showing very intriguing separation properties. This review will cover state-of-the-art of graphene-based membranes, and also provide a material guideline on future research directions suitable for practical membrane applications.

  9. Thermodynamic competition between membrane protein oligomeric states

    Science.gov (United States)

    Kahraman, Osman; Haselwandter, Christoph A.

    2016-10-01

    Self-assembly of protein monomers into distinct membrane protein oligomers provides a general mechanism for diversity in the molecular architectures, and resulting biological functions, of membrane proteins. We develop a general physical framework describing the thermodynamic competition between different oligomeric states of membrane proteins. Using the mechanosensitive channel of large conductance as a model system, we show how the dominant oligomeric states of membrane proteins emerge from the interplay of protein concentration in the cell membrane, protein-induced lipid bilayer deformations, and direct monomer-monomer interactions. Our results suggest general physical mechanisms and principles underlying regulation of protein function via control of membrane protein oligomeric state.

  10. Microfiltration: Membrane development and module design

    Science.gov (United States)

    Roesink, Hendrik Dirk Willem

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

  11. Thermodynamic competition between membrane protein oligomeric states

    CERN Document Server

    Kahraman, Osman

    2016-01-01

    Self-assembly of protein monomers into distinct membrane protein oligomers provides a general mechanism for diversity in the molecular architectures, and resulting biological functions, of membrane proteins. We develop a general physical framework describing the thermodynamic competition between different oligomeric states of membrane proteins. Using the mechanosensitive channel of large conductance as a model system, we show how the dominant oligomeric states of membrane proteins emerge from the interplay of protein concentration in the cell membrane, protein-induced lipid bilayer deformations, and direct monomer-monomer interactions. Our results suggest general physical mechanisms and principles underlying regulation of protein function via control of membrane protein oligomeric state.

  12. New process for high temperature polybenzimidazole membrane production and its impact on the membrane and the membrane electrode assembly

    Science.gov (United States)

    Liu, Zhenyu; Tsou, Yu-Min; Calundann, Gordon; De Castro, Emory

    Water addition is a key step in the new process developed at BASF Fuel Cell Inc. (BFC) for polybenzimidazole (PBI) membrane production. The added water prevents further polymerization and controls the solution viscosity for easier membrane casting. For large-scale PBI membrane production, a certain amount of tension is necessary during membrane upwinding. The applied tension could affect the polymer orientation and result in anisotropic membrane mechanical properties and proton conductivity. The membrane prepared with tension shows higher elastic modulus and proton conductivity in machine direction, which might suggest some degree of polymer chain orientation. However, the membrane electrode assembly (MEA) performance is not affected by the membrane's apparent anisotropic character. However, we observed performance variation as a function of MEA break-in condition, which might be explained by the formation of a phosphate anion concentration gradient during MEA operation.

  13. New process for high temperature polybenzimidazole membrane production and its impact on the membrane and the membrane electrode assembly

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Zhenyu; Tsou, Yu-Min; Calundann, Gordon; De Castro, Emory [BASF Fuel Cell Inc., 39 Veronica Avenue, Somerset, NJ 08873 (United States)

    2011-02-01

    Water addition is a key step in the new process developed at BASF Fuel Cell Inc. (BFC) for polybenzimidazole (PBI) membrane production. The added water prevents further polymerization and controls the solution viscosity for easier membrane casting. For large-scale PBI membrane production, a certain amount of tension is necessary during membrane upwinding. The applied tension could affect the polymer orientation and result in anisotropic membrane mechanical properties and proton conductivity. The membrane prepared with tension shows higher elastic modulus and proton conductivity in machine direction, which might suggest some degree of polymer chain orientation. However, the membrane electrode assembly (MEA) performance is not affected by the membrane's apparent anisotropic character. However, we observed performance variation as a function of MEA break-in condition, which might be explained by the formation of a phosphate anion concentration gradient during MEA operation. (author)

  14. Assessment of ceramic membrane filters

    Energy Technology Data Exchange (ETDEWEB)

    Ahluwalia, R.K.; Geyer, H.K.; Im, K.H. [and others

    1995-08-01

    The objectives of this project include the development of analytical models for evaluating the fluid mechanics of membrane coated, dead-end ceramic filters, and to determine the effects of thermal and thermo-chemical aging on the material properties of emerging ceramic hot gas filters. A honeycomb cordierite monolith with a thin ceramic coating and a rigid candle filter were evaluated.

  15. Challenges in Commercializing Biomimetic Membranes

    Directory of Open Access Journals (Sweden)

    Mark Perry

    2015-11-01

    Full Text Available The discovery of selective water channel proteins—aquaporins—has prompted growing interest in using these proteins, as the building blocks for designing new types of membranes. However, as with any other new and potentially disruptive technology, barriers for successful market entry exist. One category includes customer-related barriers, which can be influenced to some extent. Another category includes market-technical-related barriers, which can be very difficult to overcome by an organization/company aiming at successfully introducing their innovation on the market—in particular if both the organization and the technology are at early stages. Often, one faces barriers from both these categories at the same time, which makes it necessary to gain insight of the particular market when introducing a new innovative product. In this review we present the basic concepts and discuss some of these barriers and challenges associated with introducing biomimetic aquaporin membranes. These include technical issues in membrane production and product testing. Then we discuss possible business models for introducing new technologies in general, followed by a presentation of beach-head market segments relevant for biomimetic aquaporin membranes.

  16. Osmosis and the Marvelous Membrane.

    Science.gov (United States)

    Cocanour, Barbara; Bruce, Alease S.

    1985-01-01

    Shows how the natural membrane of a decalcified chicken egg can demonstrate the principle of osmosis within a single class period. Various glucose and saline solutions used, periods of time, physiological effects experiments, and correction for differences in initial weights are noted. (DH)

  17. A Model for Membrane Fusion

    Science.gov (United States)

    Ngatchou, Annita

    2010-01-01

    Pheochromocytoma is a tumor of the adrenal gland which originates from chromaffin cells and is characterized by the secretion of excessive amounts of neurotransmitter which lead to high blood pressure and palpitations. Pheochromocytoma contain membrane bound granules that store neurotransmitter. The release of these stored molecules into the extracellular space occurs by fusion of the granule membrane with the cell plasma membrane, a process called exocytosis. The molecular mechanism of this membrane fusion is not well understood. It is proposed that the so called SNARE proteins [1] are the pillar of vesicle fusion as their cleavage by clostridial toxin notably, Botulinum neurotoxin and Tetanus toxin abrogate the secretion of neurotransmitter [2]. Here, I describe how physical principles are applied to a biological cell to explore the role of the vesicle SNARE protein synaptobrevin-2 in easing granule fusion. The data presented here suggest a paradigm according to which the movement of the C-terminal of synaptobrevin-2 disrupts the lipid bilayer to form a fusion pore through which molecules can exit.

  18. Large scale biomimetic membrane arrays

    DEFF Research Database (Denmark)

    Hansen, Jesper Søndergaard; Perry, Mark; Vogel, Jörg

    2009-01-01

    -structured 8 x 8 aperture partition arrays with average aperture diameters of 301 +/- 5 mu m. We addressed the electro-physical properties of the lipid bilayers established across the micro-structured scaffold arrays by controllable reconstitution of biotechnological and physiological relevant membrane...

  19. Force dynamique des membranes fluides

    Science.gov (United States)

    Evans, Evan; Heinrich, Volkmar

    2003-03-01

    Rupturing fluid membrane vesicles with a steady ramp of micropipette suction yields a tension distribution that images the kinetic process of membrane failure. When plotted on a log scale of tension loading rate, the distribution peaks (membrane strengths) define a dynamic tension spectrum with distinct regimes that reflect passage of prominent energy barriers along the pathway to rupture. Demonstrated here by tests on giant PC lipid vesicles over loading rates from 0.06-60 mN/m/s, the stochastic process of rupture can be modelled as a causal sequence of two thermally-activated transitions where each transition governs membrane strength on separate scales of loading rate. Under fast ramps of tension, a steep linear regime appears in each spectrum at high strengths which implies that failure requires nucleation of a rare nanoscale defect. The slope and projected intercept yield defect size and spontaneous production rate respectively. However, under slow ramps of loading, the spectrum crosses over to a shallow-curved regime at lower strength, which is consistent with the kinetic impedance to opening an unstable hole in a fluid film. The dependence of rupture tension on rate reveals hole edge energy and frequency scale for thermal fluctuations in size. To cite this article: E. Evans, V. Heinrich, C. R. Physique 4 (2003).

  20. Stimuli-responsive smart gating membranes.

    Science.gov (United States)

    Liu, Zhuang; Wang, Wei; Xie, Rui; Ju, Xiao-Jie; Chu, Liang-Yin

    2016-02-07

    Membranes are playing paramount roles in the sustainable development of myriad fields such as energy, environmental and resource management, and human health. However, the unalterable pore size and surface properties of traditional porous membranes restrict their efficient applications. The performances of traditional membranes will be weakened upon unavoidable membrane fouling, and they cannot be applied to cases where self-regulated permeability and selectivity are required. Inspired by natural cell membranes with stimuli-responsive channels, artificial stimuli-responsive smart gating membranes are developed by chemically/physically incorporating stimuli-responsive materials as functional gates into traditional porous membranes, to provide advanced functions and enhanced performances for breaking the bottlenecks of traditional membrane technologies. Smart gating membranes, integrating the advantages of traditional porous membrane substrates and smart functional gates, can self-regulate their permeability and selectivity via the flexible adjustment of pore sizes and surface properties based on the "open/close" switch of the smart gates in response to environmental stimuli. This tutorial review summarizes the recent developments in stimuli-responsive smart gating membranes, including the design strategies and the fabrication strategies that are based on the introduction of the stimuli-responsive gates after or during membrane formation, and the positively and negatively responsive gating models of versatile stimuli-responsive smart gating membranes, as well as the advanced applications of smart gating membranes for regulating substance concentration in reactors, controlling the release rate of drugs, separating active molecules based on size or affinity, and the self-cleaning of membrane surfaces. With self-regulated membrane performances, smart gating membranes show great power for use in global sustainable development.

  1. Corrugated Membrane Fuel Cell Structures

    Energy Technology Data Exchange (ETDEWEB)

    Grot, Stephen [President, Ion Power Inc.

    2013-09-30

    One of the most challenging aspects of traditional PEM fuel cell stacks is the difficulty achieving the platinum catalyst utilization target of 0.2 gPt/kWe set forth by the DOE. Good catalyst utilization can be achieved with state-of-the-art catalyst coated membranes (CCM) when low catalyst loadings (<0.3 mg/cm2) are used at a low current. However, when low platinum loadings are used, the peak power density is lower than conventional loadings, requiring a larger total active area and a larger bipolar plate. This results in a lower overall stack power density not meeting the DOE target. By corrugating the fuel cell membrane electrode structure, Ion Power?s goal is to realize both the Pt utilization targets as well as the power density targets of the DOE. This will be achieved by demonstrating a fuel cell single cell (50 cm2) with a twofold increase in the membrane active area over the geometric area of the cell by corrugating the MEA structure. The corrugating structure must be able to demonstrate the target properties of < 10 mOhm-cm2 electrical resistance at > 20 psi compressive strength over the active area, in combination with offering at least 80% of power density that can be achieved by using the same MEA in a flat plate structure. Corrugated membrane fuel cell structures also have the potential to meet DOE power density targets by essentially packaging more membrane area into the same fuel cell volume as compared to conventional stack constructions.

  2. Cell-free system for synthesizing membrane proteins cell free method for synthesizing membrane proteins

    Science.gov (United States)

    Laible, Philip D; Hanson, Deborah K

    2013-06-04

    The invention provides an in vitro method for producing proteins, membrane proteins, membrane-associated proteins, and soluble proteins that interact with membrane-associated proteins for assembly into an oligomeric complex or that require association with a membrane for proper folding. The method comprises, supplying intracytoplasmic membranes from organisms; modifying protein composition of intracytoplasmic membranes from organism by modifying DNA to delete genes encoding functions of the organism not associated with the formation of the intracytoplasmic membranes; generating appropriate DNA or RNA templates that encode the target protein; and mixing the intracytoplasmic membranes with the template and a transcription/translation-competent cellular extract to cause simultaneous production of the membrane proteins and encapsulation of the membrane proteins within the intracytoplasmic membranes.

  3. Electrophoretic separation method for membrane pore-forming proteins in multilayer lipid membranes.

    Science.gov (United States)

    Okamoto, Yukihiro; Tsujimoto, Yusuke; Umakoshi, Hiroshi

    2016-03-01

    In this paper, we report on a novel electrophoretic separation and analysis method for membrane pore-forming proteins in multilayer lipid membranes (MLMs) in order to overcome the problems related to current separation and analysis methods of membrane proteins, and to obtain a high-performance separation method on the basis of specific properties of the lipid membranes. We constructed MLMs, and subsequently characterized membrane pore-forming protein behavior in MLMs. Through the use of these MLMs, we were able to successfully separate and analyze membrane pore-forming proteins in MLMs. To the best of our knowledge, this research is the first example of membrane pore-forming protein separation in lipid membranes. Our method can be expected to be applied for the separation and analysis of other membrane proteins including intrinsic membrane proteins and to result in high-performance by utilizing the specific properties of lipid membranes.

  4. Dense ceramic catalytic membranes and membrane reactors for energy and environmental applications.

    Science.gov (United States)

    Dong, Xueliang; Jin, Wanqin; Xu, Nanping; Li, Kang

    2011-10-21

    Catalytic membrane reactors which carry out separation and reaction in a single unit are expected to be a promising approach to achieve green and sustainable chemistry with less energy consumption and lower pollution. This article presents a review of the recent progress of dense ceramic catalytic membranes and membrane reactors, and their potential applications in energy and environmental areas. A basic knowledge of catalytic membranes and membrane reactors is first introduced briefly, followed by a short discussion on the membrane materials including their structures, composition and strategies for material development. The configuration of catalytic membranes, the design of membrane reaction processes and the high temperature sealing are also discussed. The performance of catalytic membrane reactors for energy and environmental applications are summarized and typical catalytic membrane reaction processes are presented and discussed. Finally, current challenges and difficulties related to the industrialization of dense ceramic membrane reactors are addressed and possible future research is also outlined.

  5. Micro-and/or nano-scale patterned porous membranes, methods of making membranes, and methods of using membranes

    KAUST Repository

    Wang, Xianbin

    2015-01-22

    Embodiments of the present disclosure provide for materials that include a pre-designed patterned, porous membrane (e.g., micro- and/or nano-scale patterned), structures or devices that include a pre-designed patterned, porous membrane, methods of making pre-designed patterned, porous membranes, methods of separation, and the like.

  6. 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.

  7. Cell Membrane Softening in Cancer Cells

    Science.gov (United States)

    Schmidt, Sebastian; Händel, Chris; Käs, Josef

    Biomechanical properties are useful characteristics and regulators of the cell's state. Current research connects mechanical properties of the cytoskeleton to many cellular processes but does not investigate the biomechanics of the plasma membrane. We evaluated thermal fluctuations of giant plasma membrane vesicles, directly derived from the plasma membranes of primary breast and cervical cells and observed a lowered rigidity in the plasma membrane of malignant cells compared to non-malignant cells. To investigate the specific role of membrane rigidity changes, we treated two cell lines with the Acetyl-CoA carboxylase inhibitor Soraphen A. It changed the lipidome of cells and drastically increased membrane stiffness by up regulating short chained membrane lipids. These altered cells had a decreased motility in Boyden chamber assays. Our results indicate that the thermal fluctuations of the membrane, which are much smaller than the fluctuations driven by the cytoskeleton, can be modulated by the cell and have an impact on adhesion and motility.

  8. Self-assembled Block Copolymer Membrane

    KAUST Repository

    Peinemann, Klaus-Viktor

    2012-12-20

    Embodiments of the invention include methods for the production of porous membranes. In certain aspects the methods are directed to producing polymeric porous membranes having a narrow pore size distribution.

  9. Electron microscopic observation of preretinal membranes.

    Science.gov (United States)

    Yamamoto, T; Yamashita, H; Hori, S

    1989-01-01

    In this report, membranes removed during vitrectomy were observed by various methods of electron microscopy to determine their three-dimensional structure and the mechanism of the contraction of preretinal membranes. The vitreous side surface of the preretinal membranes was covered by two types of flat cells, cells with long, extended processes and cells in a pavement arrangement. The lamellae of the flat cells in the internal structures of the preretinal membranes were also observed. In each lamella, the cells appeared to have a connection with each other and formed networks. The retinal side surface of the preretinal membranes was smooth and acellular. The glycerinated preretinal membranes were exposed to ATP and Mg2+, which induced the contraction of the component cells of the preretinal membranes. When the cells on the vitreous side surface of the preretinal membranes contracted, the intercellular connections among them appeared to be preserved.

  10. Anaerobic membrane bioreactor under extreme conditions (poster)

    NARCIS (Netherlands)

    Munoz Sierra, J.D.; De Kreuk, M.K.; Spanjers, H.; Van Lier, J.B.

    2013-01-01

    Membrane bioreactors ensure biomass retention by the application of micro or ultrafiltration processes. This allows operation at high sludge concentrations. Previous studies have shown that anaerobic membrane bioreactors is an efficient way to retain specialist microorganisms for treating wastewater

  11. Microfiltration : membrane development and module design

    NARCIS (Netherlands)

    Roesink, Hendrik Dirk Willem

    1989-01-01

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

  12. Carbon membranes precursor, preparation, and funtionalization

    NARCIS (Netherlands)

    Barsema, Jonathan Nathaniel

    2004-01-01

    In this thesis we study the preparation of Carbon Molecular Sieve (CMS) membranes for the separation of gases. The gases are separated based on their size difference and affinity for the membrane material.

  13. Iontophoretic Transport Across a Multiple Membrane System

    OpenAIRE

    Molokhia, Sarah A.; Zhang, Yanhui; Higuchi, William I.; Li, S. Kevin

    2008-01-01

    The objective of the present study was to investigate the iontophoretic transport behavior across multiple membranes of different barrier properties. Spectra/Por® (SP) and Ionac membranes were the synthetic membranes and sclera was the biomembrane in this model study. The barrier properties of SP membranes were determined individually in passive and iontophoresis transport experiments with tetraethylammonium ion (TEA), chloride ion (Cl), and mannitol as the model permeants. Passive and iontop...

  14. Expression and structural analysis of membrane proteins

    OpenAIRE

    Eifler, Nora

    2006-01-01

    1.1 Membrane Proteins Between one quarter and one third of all genes in eukaryotic and prokaryotic organisms code for integral membrane proteins (IMPs) (Essen, 2002). These proteins are essential parts of biological membranes and confer various functions, such as energy conversion, transport, biosynthesis of lipids, signal transduction, or cell recognition. The enormous economical potential of membrane proteins is highlighted by the family of G-protein-coupled receptors (GPC...

  15. Altered expression of connexin43 and its possible role in endothelin - 1 - induced contraction in rabbit basilar artery%缝隙连接蛋白43在内皮素诱导的脑基底动脉收缩中的表达变化

    Institute of Scientific and Technical Information of China (English)

    赵万巨; 王海涛; 洪涛

    2011-01-01

    目的 探讨Cx43在内皮素诱导的脑基底动脉收缩中的表达变化及其可能的作用.方法 血管环张力实验检测内皮素诱导的脑基底动脉的收缩变化并应用Western blot检测基底动脉Cx43蛋白的表达变化,染料传输实验用来检测脑基底动脉收缩过程中平滑肌细胞间缝隙连接的功能变化.结果 浓度递增的内皮素导致脑基底动脉呈显著浓度依赖性的收缩,一定浓度缝隙连接阻断剂苷珀酸显著缓解该收缩;收缩过程中,Cx43的蛋白表达呈显著时间依赖性的升高,苷珀酸减弱该表达的升高;内皮素刺激下,血管平滑肌细胞间的染料传输呈时间依赖性的升高,苷珀酸显著减少染料在细胞间的传输.结论 脑血管痉挛过程中,通过增加Cx43的表达,血管细胞间缝隙连接的功能被内皮素激活并在血管痉挛病理过程中发挥重要作用;抑制缝隙连接的功能是有效缓解蛛网膜下腔出血后脑血管痉挛的新途径.%Objective To investigate the role of connexin43 in ET- 1 -induced contraction in rabbit basilar artery.Methods The ET - 1 - induced contraction without or with carbenoxolone was studied with an isometric tension system.The expression of connexin43 protein in ET - t stimulated basilar arteries was studied with Western blot.Scrape/scratch method was used to analyze the function of gap junction in cultured rabbit cerebrovascular smooth muscle ceils.Results ET - 1 produced a concentration - dependent contraction.Carbenoxolone inhibited ET- 1 induced contraction.The connexin43 protein level was increased in ET- 1stimulated basilar arteries.Carbenoxolone decreased the connexin43 protein level increased by ET - 1.Cells treated with ET - 1 appeared positive communication and the dye transfer was increased in a time - dependent fashion.Carbenoxolone suppressed the ET - 1 - induced increasement of dye transfer.Conclusions The enhancement of gap junction intercellular communication is

  16. Exploration of the relationship between the enhanecment degree and location of basilar artery plaque and infar ction with MRI3D-SPACE%MRI3D-SPACE探讨基底动脉斑块位置和增强度与梗死的关系

    Institute of Scientific and Technical Information of China (English)

    张红梅; 孙雪园; 陈新; 牛琰鑫

    2016-01-01

    目的 应用3T MRI(3T magnetic resonance imaging, MRI),三维快速自旋回波(3D sampling perfection with ap-plication-optimized contrasts using different flip angle evolutions , 3D-SPACE)序列显示症状性动脉粥样硬化患者基底动脉管壁硬化斑块,通过斑块形态学特征及增强度,评估其与梗死的关系. 方法 103例症状性后循环缺血患者行3D-SPACE序列扫描,测量基底动脉斑块及邻近正常脑灰质信号强度,二者得出基底动脉斑块相对增强度,且划分为:轻度强化(1%~10%)、中度强化(10%~100%)、明显强化(100%以上);研究急性联合亚急性梗死(A组)、慢性及无梗死(B组)与基底动脉斑块相对增强度的关系. DWI图像评估有无近期梗死灶. 结果 100例有症状患者纳入统计,急性梗死46例、亚急性梗死26例 、慢性期梗死15 例、无梗死13 例. 梗死部位包括脑干、桥臂、小脑半球、枕叶、中脑、丘脑及延髓. 3 D-SPACE序列能多角度显示基底动脉斑块,偏心性斑块70例,且斑块位于基底动脉腹侧壁更易发生梗死;斑块相对增强度>100%更易发生梗死;急性联合亚急性梗死( A组)、慢性及无梗死( B组)两组之间斑块增强度比较存在差异;在脑梗死分期时斑块明显强化与轻度强化、中度强化之间有统计学意义( P值100%).Then, the relationship between both acute joint subacute infarction (group A), chronic and no infarction (group B) with basilar artery plaque enhancement degree was studied .DWI image was used to assess whether the recent infarcts occurred or not .Results Of those 100 patients who were included in the statistics , 46 were suffered from acute infarction , 26 from subacute infarction , and 15 from chronic infarction , and 13had no infarction .The infarct parts included the brain stem , bridge arm, cerebellum, occipital lobe, the midbrain and hypothalamus and medulla oblon -gata.3 D-SPACE sequence can display the basal artery plaque with multi

  17. Mechanism of calcium mitigating membrane fouling in submerged membrane bioreactors

    Institute of Scientific and Technical Information of China (English)

    ZHANG Hanmin; XIA Jie; YANG Yang; WANG Zixing; YANG Fenglin

    2009-01-01

    Two parallel membrane bioreactors (MBRs) were operated under different calcium dosages (168.5, 27 mg/L) to gain a better understanding of the mechanism of retarding membrane fouling by the addition of calcium.The results showed that the particle size of sludge flocs increased and the particle size distribution tended to be narrow at the optimum dosage (168.5 mg/L).Calcium was effective in decreasing loosely bound extracellular polymeric substances (LB-EPS) in microbial flocs and soluble microbial products (SMP) in the supernatant at the dosage of 168.5 mg/L by strengthening the neutralization and bridging of EPS with flocs.Furthermore, the amount of CODS and CODC decreased in both the mixed liquor and the fouling cake layer on the membrane surface.In order to compare the filtration characteristics of cake layers from the MBRs with the two calcium dosages, the specific cake resistance and the compressibility coefficient were measured.The specific cake resistance from the MBR with optimum dosage (168.5 mg/L) was distinctly lower than that with low dosage (27 mg/L).The compressibility coefficient of the cake layers under different dosages were respectively attained as 0.65, 0.91.Scanning electron microscopy (SEM) and three-dimensional confocal scanning laser microscope analysis (CLSM) images were utilized to observe the gel layer directly.

  18. Robust High Performance Aquaporin based Biomimetic Membranes

    DEFF Research Database (Denmark)

    Helix Nielsen, Claus; Zhao, Yichun; Qiu, C.;

    2013-01-01

    on top of a support membrane. Control membranes, either without aquaporins or with the inactive AqpZ R189A mutant aquaporin served as controls. The separation performance of the membranes was evaluated by cross-flow forward osmosis (FO) and reverse osmosis (RO) tests. In RO the ABM achieved a water...

  19. Preparation of Zeolite—metal Composite Membrane

    Institute of Scientific and Technical Information of China (English)

    JieLIU; XiaoBoCHEN; 等

    2002-01-01

    A NaA Zeolite membrane was synthesized on the surface of the stainless steel slab. The membrane was characterized by XRD and SEM. The membrane was continuous and highly intergrown. The size of NaA zeolite crystals was about 5-6μm.

  20. Solar driven membrane pervaporation for desalination processes

    NARCIS (Netherlands)

    Zwijnenberg, H.J.; Koops, G.H.; Wessling, M.

    2005-01-01

    We describe details of a solar driven pervaporation process for the production of desalinated water from highly contaminated waters. The membrane material is a polyetheramide-based polymer film of 40 ¿m thickness. This Solar Dew® membrane is used in a tubular configuration in a direct solar membrane

  1. Flue gas treatment with membrane gas absorption

    NARCIS (Netherlands)

    Klaassen, R.; Feron, P.H.M.; Jansen, A.E.

    1998-01-01

    Dutch researchers from the TN0 Institute have developed a technique to carry out gas-liquid contacting operations using hollow fibre membranes in combination with an absorption liquid. The method known as membrane gas absorption, aims to combine the advantages of membrane technology (compactness, fl

  2. 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...

  3. Rigid rod anchored to infinite membrane.

    Science.gov (United States)

    Guo, Kunkun; Qiu, Feng; Zhang, Hongdong; Yang, Yuliang

    2005-08-15

    We investigate the shape deformation of an infinite membrane anchored by a rigid rod. The density profile of the rod is calculated by the self-consistent-field theory and the shape of the membrane is predicted by the Helfrich membrane elasticity theory [W. Helfrich, Z. Naturforsch. 28c, 693 (1973)]. It is found that the membrane bends away from the rigid rod when the interaction between the rod and the membrane is repulsive or weakly attractive (adsorption). However, the pulled height of the membrane at first increases and then decreases with the increase of the adsorption strength. Compared to a Gaussian chain with the same length, the rigid rod covers much larger area of the membrane, whereas exerts less local entropic pressure on the membrane. An evident gap is found between the membrane and the rigid rod because the membrane's curvature has to be continuous. These behaviors are compared with that of the flexible-polymer-anchored membranes studied by previous Monte Carlo simulations and theoretical analysis. It is straightforward to extend this method to more complicated and real biological systems, such as infinite membrane/multiple chains, protein inclusion, or systems with phase separation.

  4. Flue gas treatment with membrane gas absorption

    NARCIS (Netherlands)

    Klaassen, R.; Feron, P.H.M.; Jansen, A.E.

    1998-01-01

    Membrane gas absorption is a new, efficient and flexible way to carry out gas-liquid contacting operations with hollow fibre membranes. Advantages of gas absorption membranes over conventional G-L contactors are: -High specific surface area and rapid mass transfer resulting in very compact and low w

  5. Preparation of Zeolite-metal Composite Membrane

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    A NaA zeolite membrane was synthesized on the surface of the stainless steel slab. The membrane was characterized by XRD and SEM. The membrane was continuous and highly intergrown. The size of NaA zeolite crystals was about 5 ~ 6 mm.

  6. Membranes for Environmentally Friendly Energy Processes

    Directory of Open Access Journals (Sweden)

    Xuezhong He

    2012-10-01

    Full Text Available Membrane separation systems require no or very little chemicals compared to standard unit operations. They are also easy to scale up, energy efficient, and already widely used in various gas and liquid separation processes. Different types of membranes such as common polymers, microporous organic polymers, fixed-site-carrier membranes, mixed matrix membranes, carbon membranes as well as inorganic membranes have been investigated for CO2 capture/removal and other energy processes in the last two decades. The aim of this work is to review the membrane systems applied in different energy processes, such as post-combustion, pre-combustion, oxyfuel combustion, natural gas sweetening, biogas upgrading, hydrogen production, volatile organic compounds (VOC recovery and pressure retarded osmosis for power generation. Although different membranes could probably be used in a specific separation process, choosing a suitable membrane material will mainly depend on the membrane permeance and selectivity, process conditions (e.g., operating pressure, temperature and the impurities in a gas stream (such as SO2, NOx, H2S, etc.. Moreover, process design and the challenges relevant to a membrane system are also being discussed to illustrate the membrane process feasibility for a specific application based on process simulation and economic cost estimation.

  7. Proteins and Peptides in Biomimetic Polymeric Membranes

    DEFF Research Database (Denmark)

    Perez, Alfredo Gonzalez

    2013-01-01

    This chapter discusses recent advances and the main advantages of block copolymers for functional membrane protein reconstitution in biomimetic polymeric membranes. A rational approach to the reconstitution of membrane proteins in a functional form can be addressed by a more holistic view by usin...

  8. Biofouling of spiral wound membrane systems

    NARCIS (Netherlands)

    Vrouwenvelder, J.S.

    2009-01-01

    Biofouling of spiral wound membrane systems High quality drinking water can be produced with membrane filtration processes like reverse osmosis (RO) and nanofiltration (NF). Because the global demand for fresh clean water is increasing, these membrane technologies will increase in importance in the

  9. On-chip electro membrane extraction

    DEFF Research Database (Denmark)

    Petersen, Nickolaj Jacob; Jensen, Henrik; Hansen, Steen Honore

    2010-01-01

    ) was created by locally filling the pores of the membrane with 2-nitrophenyl octyl ether (NPOE). The sample solution, containing five basic model analytes in 10 mM HCI or urine was pumped through the 50 mu m deep donor channel on one side of the membrane. With 15 V applied across the membrane, the protonated...

  10. Lipid organization of the plasma membrane

    NARCIS (Netherlands)

    Ingólfsson, Helgi I; Melo, Manuel N; van Eerden, Floris J; Arnarez, Clément; Lopez, Cesar A; Wassenaar, Tsjerk A; Periole, Xavier; de Vries, Alex H; Tieleman, D Peter; Marrink, Siewert J

    2014-01-01

    The detailed organization of cellular membranes remains rather elusive. Based on large-scale molecular dynamics simulations, we provide a high-resolution view of the lipid organization of a plasma membrane at an unprecedented level of complexity. Our plasma membrane model consists of 63 different li

  11. Membrane analysis with amphiphilic carbon dots.

    Science.gov (United States)

    Nandi, Sukhendu; Malishev, Ravit; Parambath Kootery, Kaviya; Mirsky, Yelena; Kolusheva, Sofiya; Jelinek, Raz

    2014-09-14

    Newly-synthesized amphiphilic carbon dots were used for spectroscopic analysis and multicolour microscopic imaging of membranes and live cells. We show that Förster resonance energy transfer (FRET) occurred from the amphiphilic carbon dots to different membrane-associated fluorescence acceptors. The amphiphilic carbon dots enabled imaging of membrane disruption by the beta-amyloid peptide.

  12. Donnan Membrane Technique (DMT) for Anion Measurement

    NARCIS (Netherlands)

    Alonso Vega, M.F.; Weng, L.P.; Temminghoff, E.J.M.; Riemsdijk, van W.H.

    2010-01-01

    Donnan membrane technique (DMT) is developed and tested for determination of free anion concentrations. Time needed to reach the Donnan membrane equilibrium depends on type of ions and the background. The Donnan membrane equilibrium is reached in 1 day for Cl-, 1-2 days for NO3-, 1-4 days for SO42-

  13. A review of water treatment membrane nanotechnologies

    KAUST Repository

    Pendergast, MaryTheresa M.

    2011-01-01

    Nanotechnology is being used to enhance conventional ceramic and polymeric water treatment membrane materials through various avenues. Among the numerous concepts proposed, the most promising to date include zeolitic and catalytic nanoparticle coated ceramic membranes, hybrid inorganic-organic nanocomposite membranes, and bio-inspired membranes such as hybrid protein-polymer biomimetic membranes, aligned nanotube membranes, and isoporous block copolymer membranes. A semi-quantitative ranking system was proposed considering projected performance enhancement (over state-of-the-art analogs) and state of commercial readiness. Performance enhancement was based on water permeability, solute selectivity, and operational robustness, while commercial readiness was based on known or anticipated material costs, scalability (for large scale water treatment applications), and compatibility with existing manufacturing infrastructure. Overall, bio-inspired membranes are farthest from commercial reality, but offer the most promise for performance enhancements; however, nanocomposite membranes offering significant performance enhancements are already commercially available. Zeolitic and catalytic membranes appear reasonably far from commercial reality and offer small to moderate performance enhancements. The ranking of each membrane nanotechnology is discussed along with the key commercialization hurdles for each membrane nanotechnology. © 2011 The Royal Society of Chemistry.

  14. Recycling from endosomes to the plasma membrane

    NARCIS (Netherlands)

    Dam, E.M. van

    2001-01-01

    Summary V Chapter?Summary Many membrane proteins are, after endocytic uptake, efficiently recycled back to the plasma membrane. The aim of the studies presented in this thesis was to determine pathways and molecular mechanisms that are involved in recycling. Plasma membrane-derived clathrin-coated v

  15. Submerged membrane distillation for desalination of water

    KAUST Repository

    Francis, Lijo

    2016-10-27

    Submerged membrane modules for use for desalination of water are disclosed. In one or more aspects, the membrane modules can be submerged either in a feed solution tank or the feed solution can pass through the lumen side of the membrane submerged within the tank. The feed solution can be a water-based feed stream containing an amount of salt.

  16. Pollen viability and membrane lipid composition.

    NARCIS (Netherlands)

    Bilsen, van D.G.J.L.

    1993-01-01

    In this thesis membrane lipid composition is studied in relation to pollen viability during storage. Chapter 1 reviews pollen viability, membranes in the dry state and membrane changes associated with cellular aging. This chapter is followed by a study of age-related changes in phospholipid composit

  17. Characterization of Surface Modification of Polyethersulfone Membrane

    Science.gov (United States)

    Surface modification of polyethersulfone (PES) membrane surface using UV/ozone-treated grafting and interfacial polymerization on membrane surface was investigated in order to improve the resistance of membrane surface to protein adsorption. These methods of surface modification were compared in te...

  18. VARIATION IN MEMBRANE PROPERTIES FROM THE ACTION OF LAMININ ON MEMBRANE RECEPTORS

    Institute of Scientific and Technical Information of China (English)

    苏雅娴; 薛燕玲; 肖军军

    1995-01-01

    Biophysical studies were conducted on the action of laminin through membrane receptors of cancer cells. The results showed that variations occurred in the thermodynamic properties of membrane proteins, the mobility of hydrocarbon chains of membrane lipids, and the permeshility and transportation pathways of the membrane.

  19. Membrane topology and insertion of membrane proteins : Search for topogenic signals

    NARCIS (Netherlands)

    Geest, Marleen van; Lolkema, Juke S.

    2000-01-01

    Integral membrane proteins are found in all cellular membranes and carry out many of the functions that are essential to life. The membrane-embedded domains of integral membrane proteins are structurally quite simple, allowing the use of various prediction methods and biochemical methods to obtain s

  20. 倍他司汀联合氟桂利嗪治疗椎基底动脉供血不足的临床研究%Betahistine combined flunarizine clinical research for the treatment of vertebral basilar artery blood supply shortage

    Institute of Scientific and Technical Information of China (English)

    徐倩

    2015-01-01

    Objective:to observe betahistine combined flunarizine curative effect for the treatment of vertebral basilar artery blood supply deficiency. Methods:all cases were randomly divided into flunarizine group and combination group. Flunarizine group was given flunarizine capsules treatment; Combined:treatment group on the basis of the given betahistine injection treatment. Using transcranial doppler blood flow after treatment diagnosis system (TCD) detection of blood flow, observe two groups of treatment effect. Results of combined treatment group effective than flunarizine group, P<0.05. After the two groups after treatment, the blood flow anomalies have been improved to a certain extent, the joint treatment group on the improvement of their blood flow abnormalities than flunarizine group, P<0.05. Conclusion:betahistine combined flunarizine vertebral basilar artery blood supply deficiency is safe and effective treatment.%目的:观察倍他司汀联合氟桂利嗪治疗椎基底动脉供血不足的疗效。方法:将所有病例随机分为氟桂利嗪组和联合治疗组。氟桂利嗪组给予氟桂利嗪胶囊治疗;联合治疗组在此基础上给予倍他司汀口服治疗。治疗后使用经颅多普勒血流诊断系统(TCD)检测血流情况,观察两组治疗效果。结果:联合治疗组的有效率高于氟桂利嗪组,P<0.05。两组经过治疗,血流异常情况得到改善,联合治疗组血流异常情况的改善情况要优于氟桂利嗪组,P<0.05。结论:倍他司汀联合氟桂利嗪治疗椎基底动脉供血不足安全有效。

  1. Laminins in basement membrane assembly.

    Science.gov (United States)

    Hohenester, Erhard; Yurchenco, Peter D

    2013-01-01

    The heterotrimeric laminins are a defining component of all basement membranes and self-assemble into a cell-associated network. The three short arms of the cross-shaped laminin molecule form the network nodes, with a strict requirement for one α, one β and one γ arm. The globular domain at the end of the long arm binds to cellular receptors, including integrins, α-dystroglycan, heparan sulfates and sulfated glycolipids. Collateral anchorage of the laminin network is provided by the proteoglycans perlecan and agrin. A second network is then formed by type IV collagen, which interacts with the laminin network through the heparan sulfate chains of perlecan and agrin and additional linkage by nidogen. This maturation of basement membranes becomes essential at later stages of embryo development.

  2. Energy efficiency in membrane bioreactors.

    Science.gov (United States)

    Barillon, B; Martin Ruel, S; Langlais, C; Lazarova, V

    2013-01-01

    Energy consumption remains the key factor for the optimisation of the performance of membrane bioreactors (MBRs). This paper presents the results of the detailed energy audits of six full-scale MBRs operated by Suez Environnement in France, Spain and the USA based on on-site energy measurement and analysis of plant operation parameters and treatment performance. Specific energy consumption is compared for two different MBR configurations (flat sheet and hollow fibre membranes) and for plants with different design, loads and operation parameters. The aim of this project was to understand how the energy is consumed in MBR facilities and under which operating conditions, in order to finally provide guidelines and recommended practices for optimisation of MBR operation and design to reduce energy consumption and environmental impacts.

  3. Molecular Structure of Membrane Tethers

    OpenAIRE

    Baoukina, Svetlana; Marrink, Siewert J.; Tieleman, D. Peter

    2012-01-01

    Membrane tethers are nanotubes formed by a lipid bilayer. They play important functional roles in cell biology and provide an experimental window on lipid properties. Tethers have been studied extensively in experiments and described by theoretical models, but their molecular structure remains unknown due to their small diameters and dynamic nature. We used molecular dynamics simulations to obtain molecular-level insight into tether formation. Tethers were pulled from single-component lipid b...

  4. Golgi GRASPs: moonlighting membrane tethers

    Directory of Open Access Journals (Sweden)

    Jarvela T

    2012-05-01

    Full Text Available Timothy Jarvela, Adam D LinstedtDepartment of Biological Sciences, Carnegie Mellon University, Pittsburgh, PA, USAAbstract: The identification of mammalian Golgi reassembly stacking proteins (GRASPs 15 years ago was followed by experiments implicating them in diverse functions, including two differing structural roles in Golgi biogenesis and at least two distinct roles in the secretion of proteins. GRASP55 and GRASP65 are localized to cis and medial/trans Golgi cisternae, respectively. They are both required for stacking of Golgi membranes in a Golgi reassembly assay. Depletion of either GRASP from cultured cells prevents the linking of Golgi membranes into their normal ribbon-like network. While GRASPs are not required for transport of secretory cargo per se, they are required for ER-to-Golgi transport of certain specific cargo, such as those containing a C-terminal valine motif. Surprisingly, GRASPs also promote secretion of cargo by the so-called unconventional secretory pathway, which bypasses the Golgi apparatus where the GRASPs reside. Furthermore, regulation of GRASP activity is now recognized for its connections to cell cycle control, development, and disease. Underlying these diverse activities is the structurally conserved N-terminal GRASP domain whose crystal structure was recently determined. It consists of a tandem array of atypical PSD95–DlgA–Zo–1 (PDZ domains, which are well-known protein–protein interaction motifs. The GRASP PDZ domains are used to localize the proteins to the Golgi as well as GRASP-mediated membrane tethering and cargo interactions. These activities are regulated, in part, by phosphorylation of the large unstructured C-terminal domain.Keywords: GRASP, review, membrane, tether, PDZ domain, secretory chaperone, unconventional secretion

  5. Peptide Membranes in Chemical Evolution*

    OpenAIRE

    2009-01-01

    Simple surfactants achieve remarkable long-range order in aqueous environments. This organizing potential is seen most dramatically in biological membranes where phospholipid assemblies both define cell boundaries and provide a ubiquitous structural scaffold for controlling cellular chemistry. Here we consider simple peptides that also spontaneously assemble into exceptionally ordered scaffolds, and review early data suggesting that these structures maintain the functional diversity of protei...

  6. Salt splitting using ceramic membranes

    Energy Technology Data Exchange (ETDEWEB)

    Kurath, D.E. [Pacific Northwest National Lab., Richland, WA (United States)

    1997-10-01

    Many radioactive aqueous wastes in the DOE complex have high concentrations of sodium that can negatively affect waste treatment and disposal operations. Sodium can decrease the durability of waste forms such as glass and is the primary contributor to large disposal volumes. Waste treatment processes such as cesium ion exchange, sludge washing, and calcination are made less efficient and more expensive because of the high sodium concentrations. Pacific Northwest National Laboratory (PNNL) and Ceramatec Inc. (Salt Lake City UT) are developing an electrochemical salt splitting process based on inorganic ceramic sodium (Na), super-ionic conductor (NaSICON) membranes that shows promise for mitigating the impact of sodium. In this process, the waste is added to the anode compartment, and an electrical potential is applied to the cell. This drives sodium ions through the membrane, but the membrane rejects most other cations (e.g., Sr{sup +2}, Cs{sup +}). The charge balance in the anode compartment is maintained by generating H{sup +} from the electrolysis of water. The charge balance in the cathode is maintained by generating OH{sup {minus}}, either from the electrolysis of water or from oxygen and water using an oxygen cathode. The normal gaseous products of the electrolysis of water are oxygen at the anode and hydrogen at the cathode. Potentially flammable gas mixtures can be prevented by providing adequate volumes of a sweep gas, using an alternative reductant or destruction of the hydrogen as it is generated. As H{sup +} is generated in the anode compartment, the pH drops. The process may be operated with either an alkaline (pH>12) or an acidic anolyte (pH <1). The benefits of salt splitting using ceramic membranes are (1) waste volume reduction and reduced chemical procurement costs by recycling of NaOH; and (2) direct reduction of sodium in process streams, which enhances subsequent operations such as cesium ion exchange, calcination, and vitrification.

  7. Structure Prediction of Membrane Proteins

    Institute of Scientific and Technical Information of China (English)

    Chunlong Zhou; Yao Zheng; Yan Zhou

    2004-01-01

    There is a large gap between the number of membrane protein (MP) sequences and that of their decoded 3D structures, especially high-resolution structures, due to difficulties in crystal preparation of MPs. However, detailed knowledge of the 3D structure is required for the fundamental understanding of the function of an MP and the interactions between the protein and its inhibitors or activators. In this paper, some computational approaches that have been used to predict MP structures are discussed and compared.

  8. Living Membranes as Environmental Detectors

    Science.gov (United States)

    2016-02-19

    not display a currently valid OMB control number. PLEASE DO NOT RETURN YOUR FORM TO THE ABOVE ADDRESS. Tufts University 20 Professors Row Medford, MA...establishing the fundamentals to bring the living membrane concept to fruition. Chemical and biological weapons (CBW) present unique challenges with regards...of target bacteria  Genetically malleable host organism  Tailorable cellulose pellicle formulation  Biologically -driven rather than chemical

  9. Computational modeling of membrane proteins.

    Science.gov (United States)

    Koehler Leman, Julia; Ulmschneider, Martin B; Gray, Jeffrey J

    2015-01-01

    The determination of membrane protein (MP) structures has always trailed that of soluble proteins due to difficulties in their overexpression, reconstitution into membrane mimetics, and subsequent structure determination. The percentage of MP structures in the protein databank (PDB) has been at a constant 1-2% for the last decade. In contrast, over half of all drugs target MPs, only highlighting how little we understand about drug-specific effects in the human body. To reduce this gap, researchers have attempted to predict structural features of MPs even before the first structure was experimentally elucidated. In this review, we present current computational methods to predict MP structure, starting with secondary structure prediction, prediction of trans-membrane spans, and topology. Even though these methods generate reliable predictions, challenges such as predicting kinks or precise beginnings and ends of secondary structure elements are still waiting to be addressed. We describe recent developments in the prediction of 3D structures of both α-helical MPs as well as β-barrels using comparative modeling techniques, de novo methods, and molecular dynamics (MD) simulations. The increase of MP structures has (1) facilitated comparative modeling due to availability of more and better templates, and (2) improved the statistics for knowledge-based scoring functions. Moreover, de novo methods have benefited from the use of correlated mutations as restraints. Finally, we outline current advances that will likely shape the field in the forthcoming decade.

  10. 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.

  11. Arsenic Removal by Liquid Membranes

    Directory of Open Access Journals (Sweden)

    Tiziana Marino

    2015-03-01

    Full Text Available Water contamination with harmful arsenic compounds represents one of the most serious calamities of the last two centuries. Natural occurrence of the toxic metal has been revealed recently for 21 countries worldwide; the risk of arsenic intoxication is particularly high in Bangladesh and India but recently also Europe is facing similar problem. Liquid membranes (LMs look like a promising alternative to the existing removal processes, showing numerous advantages in terms of energy consumption, efficiency, selectivity, and operational costs. The development of different LM configurations has been a matter of investigation by several researching groups, especially for the removal of As(III and As(V from aqueous solutions. Most of these LM systems are based on the use of phosphine oxides as carriers, when the metal removal is from sulfuric acid media. Particularly promising for water treatment is the hollow fiber supported liquid membrane (HFSLM configuration, which offers high selectivity, easy transport of the targeted metal ions, large surface area, and non-stop flow process. The choice of organic extractant(s plays an essential role in the efficiency of the arsenic removal. Emulsion liquid membrane (ELM systems have not been extensively investigated so far, although encouraging results have started to appear in the literature. For such LM configuration, the most relevant step toward efficiency is the choice of the surfactant type and its concentration.

  12. AMNIOTIC MEMBRANE TRANSPLANTATION FOR KERATITIS.

    Directory of Open Access Journals (Sweden)

    Snezhana Murgova

    2015-06-01

    Full Text Available Keratitis without proper management tends to perforate the cornea, resulting in severe adverse consequences. In recent studies, amniotic membrane is reported to have anti-inflammatory effect and promote wound healing of corneal ulcer. Purpose: To report on the efficacy of permanent amniotic membrane transplantation (AMT in the treatment of keratitis. Case report: A 58-year-old man with severe keratitis in both eyes caused by long term administration of topical anesthetic (alcaine for electric ophthalmia. Single layer of amniotic membrane (AM was placed on the defect and secured to the limbus with interrupted 10-0 nylon sutures. A bandage contact lens was applied on the AM. Postoperative medication included topical antibiotic, artificial tears and mydriatic. Three months later corticosteroid was included. There was an immediate decrease of patient’s pain after surgery. Complete epithelialization was noted after 1 month. Conclusion: AMT is an alternative adjunctive method of treatment of keratitis; it promotes epithelialization process, decreased inflammation, corneal haze and neovascularization.

  13. Water vapor diffusion membrane development

    Science.gov (United States)

    Tan, M. K.

    1977-01-01

    An application of the water vapor diffusion technique is examined whereby the permeated water vapor is vented to space vacuum to alleviate on-board waste storage and provide supplemental cooling. The work reported herein deals primarily with the vapor diffusion-heat rejection (VD-HR) as it applies to the Space Shuttle. A stack configuration was selected, designed and fabricated. An asymmetric cellulose acetate membrane, used in reverse osmosis application was selected and a special spacer was designed to enhance mixing and promote mass transfer. A skid-mount unit was assembled from components used in the bench unit although no attempt was made to render it flight-suitable. The operating conditions of the VD-HR were examined and defined and a 60-day continuous test was carried out. The membranes performed very well throughout the test; no membrane rupture and no unusual flux decay was observed. In addition, a tentative design for a flight-suitable VD-HR unit was made.

  14. The apicomplexan inner membrane complex.

    Science.gov (United States)

    Kono, Maya; Prusty, Dhaneswar; Parkinson, John; Gilberger, Tim W

    2013-06-01

    Dinoflagellates, apicomplexans and ciliates are members of the monophyletic supergroup of Alveolata. The protists of this phylogenetic cluster have adapted to various ecological niches and lifestyles. Dinoflagellates and cilates can be found in any aquatic environment, whereas the phylum Apicomplexa solely comprises intracellular parasites. Despite their diversity all alveolates are united by the presence of membranous vesicles, so called alveoli, located beneath the plasma membrane. In addition to strengthening the cytoskeleton, these vesicles appear to possess taxon-specific functionality. In dinoflagellates and ciliates the alveoli predominantly play a structural role and can function as calcium stores. However, for the Apicomplexa, the alveolar vesicles -here jointly called the inner membrane complex (IMC)- are additionally involved in invasion of the host cell and are important scaffold elements during cytokinesis. Recent studies shed light on the architecture of the apicomplexan IMC and the number and diversity of its constituent proteins. This plethora of proteins and their varying evolutionary origin underlines the versatility of the IMC as a result of the adaption to a parasitic lifestyle.

  15. Activation of interfacial enzymes at membrane surfaces

    DEFF Research Database (Denmark)

    Mouritsen, Ole G.; Andresen, Thomas Lars; Halperin, Avi;

    2006-01-01

    A host of water-soluble enzymes are active at membrane surfaces and in association with membranes. Some of these enzymes are involved in signalling and in modification and remodelling of the membranes. A special class of enzymes, the phospholipases, and in particular secretory phospholipase A2 (s......PLA2), are only activated at the interface between water and membrane surfaces, where they lead to a break-down of the lipid molecules into lysolipids and free fatty acids. The activation is critically dependent on the physical properties of the lipid-membrane substrate. A topical review is given...

  16. In-membrane micro fuel cell

    Energy Technology Data Exchange (ETDEWEB)

    Omosebi, Ayokunle; Besser, Ronald

    2016-09-06

    An in-membrane micro fuel cell comprises an electrically-insulating membrane that is permissive to the flow of cations, such as protons, and a pair of electrodes deposited on channels formed in the membrane. The channels are arranged as conduits for fluids, and define a membrane ridge between the channels. The electrodes are porous and include catalysts for promoting the liberation of a proton and an electron from a chemical species and/or or the recombination of a proton and an electron with a chemical specie. The fuel cell may be provided a biosensor, an electrochemical sensor, a microfluidic device, or other microscale devices fabricated in the fuel cell membrane.

  17. MECHANISM OF LIQUID MEMBRANES AND APPLICATIONS

    Directory of Open Access Journals (Sweden)

    Filiz Nuran ACAR

    2002-02-01

    Full Text Available It has been considerably studied on the recycling of waste materials in the source besides of wastewater treatment in the last years. It has been important developments on the using of semiconductor membranes in the recycling of toxic materials such as heavy metals, intensifying the environment protection measures especially in the west countries. Wastewater treatment has been achieved with liquid membranes as it has been achieved with polymeric membrane systems such as ultrafiltration, microfiltration, electrodialysis. At the same time, liquid membranes are used for removal of metal ions in hydrometallurgy. Liquid membranes are also used in biotechnology, medical areas and gas separation process.

  18. Adsorption of amylase enzyme on ultrafiltration membranes

    DEFF Research Database (Denmark)

    Beier, Søren; Enevoldsen, Ann Dorrit; Kontogeorgis, Georgios

    2007-01-01

    A method to measure the static adsorption on membrane surfaces has been developed and described. The static adsorption of an amylase-F has been measured on two different ultrafiltration membranes, both with a cut-off value of 10 kDa (a PES membrane and the ETNA10PP membrane, which is a surface-mo...... is independent of the membrane type. At higher concentrations of enzyme, concentration polarization effects can not be neglected. Therefore stagnant film theory and the osmotic pressure model can describe the dependency between flux and bulk concentration....

  19. Distributed algorithms over communicating membrane systems.

    Science.gov (United States)

    Ciobanu, Gabriel

    2003-07-01

    This paper presents fundamental distributed algorithms over membrane systems with antiport carriers. We describe distributed algorithms for collecting and dispersing information, leader election in these systems, and the mutual exclusion problem. Finally, we consider membrane systems producing correct results despite some failures at some of the components or the communication links. We show that membrane systems with antiport carriers provide an appropriate model for distributed computing, particularly for message-passing algorithms interpreted here as membrane transport in both directions, namely when two chemicals behave as input and output messages and pass the membranes in both directions using antiport carriers.

  20. Preparation of Chitosan-coated Nylon Membranes and their Application as Affinity Membranes

    Institute of Scientific and Technical Information of China (English)

    Wei SHI; Feng Bao ZHANG; Guo Liang ZHANG

    2005-01-01

    Chitosan-coated nylon membranes which possess a large number of reactive groups of-CH2OH and -NH2 were prepared by coupling chitosan onto the nylon membrane. Then polylysine as ligand was also immobilized onto the composite membranes by 1, l′-carbonyldiimidazole activation to prepare affinity membranes for bilirubin adsorption. The results showed that these membranes exhibited high binding affinity capacities for bilirubin and the adsorption isotherm fitted the Freundlich model well.

  1. Membrane topology of transmembrane proteins: determinants and experimental tools.

    Science.gov (United States)

    Lee, Hunsang; Kim, Hyun

    2014-10-17

    Membrane topology refers to the two-dimensional structural information of a membrane protein that indicates the number of transmembrane (TM) segments and the orientation of soluble domains relative to the plane of the membrane. Since membrane proteins are co-translationally translocated across and inserted into the membrane, the TM segments orient themselves properly in an early stage of membrane protein biogenesis. Each membrane protein must contain some topogenic signals, but the translocation components and the membrane environment also influence the membrane topology of proteins. We discuss the factors that affect membrane protein orientation and have listed available experimental tools that can be used in determining membrane protein topology.

  2. Budded membrane microdomains as regulators for cellular tension

    OpenAIRE

    Sens, Pierre; Turner, Matthew S.

    2005-01-01

    We propose a mechanism for mechanical regulation at the membrane of living cells, based on the exchange of membrane area between the cell membrane and a membrane reservoir. The reservoir is composed of invaginated membrane microdomains which are liable to flatten upon increase of membrane strain, effectively controlling membrane tension. We show that the domain shape transition is first order, allowing for coexistence between flat and invaginated domains. During coexistence, the membrane tens...

  3. Metric dynamics for membrane transformation through regulated cell proliferation

    OpenAIRE

    Ito, Hiroshi C.

    2016-01-01

    This study develops an equation for describing three-dimensional membrane transformation through proliferation of its component cells regulated by morphogen density distributions on the membrane. The equation is developed in a two-dimensional coordinate system mapped on the membrane, referred to as the membrane coordinates. When the membrane expands, the membrane coordinates expand in the same manner so that the membrane is invariant in the coordinates. In the membrane coordinate system, the ...

  4. PEMBUATAN DAN UJI KEMAMPUAN MEMBRAN KITOSAN SEBAGAI MEMBRAN ULTRAFILTRASI UNTUK PEMISAHAN ZAT WARNA RHODAMIN B

    Directory of Open Access Journals (Sweden)

    Nita Kusumawati

    2012-05-01

    Full Text Available Telah dilakukan penelitian tentang pembuatan membran kitosan dan aplikasinya dalam pemisahan zat warna Rhodamin B. Tujuan penelitian ini adalah untuk mengetahui karakteristik fisik serta kinerja membran kitosan yang dihasilkan dalam memisahkan zat warna Rhodamin B dengan variasi konsentrasi kitosan dan tekanan operasional. Penelitian ini diawali dengan pembuatan membran dengan variasi konsentrasi kitosan, yaitu 1-5%. Membran kitosan dibuat dengan mencampurkan kitosan dalam asam asetat 1% kemudian dicetak pada cawan petri. Uji karakteristik fisik membran meliputi, kekuatan tarik dan regangan membran menggunakan Autograph, dan morfologi serta ukuran pori membran menggunakan Scanning Eletron Microscopy (SEM. Kinerja membran meliputi nilai fluks dan rejeksi, diketahui dari pengukuran menggunakan alat uji membran “dead-end” dan UV-Visible Genesys 10. Hasil penelitian menunjukkan bahwa membran kitosan yang dihasilkan masuk dalam rentang membran ultrafiltrasi. Membran memiliki daya tegang dan regang yang tinggi dengan bertambahnya konsentrasi kitosan. Nilai tegangan (Load yang diperoleh sebesar 0,1531–2,8571 kgf dan nilai regangan (Stroke sebesar 2,86-5,48%. Semakin besar konsentrasi kitosan dalam membran akan menghasilkan fluks yang kecil. Nilai fluks terbaik dihasilkan oleh membran kitosan 1% pada tekanan 5 kg/cm2 yakni sebesar 38,372 L/m2 jam. Sedangkan nilai koefisien rejeksi tertinggi dihasilkan oleh membran kitosan 3% pada tekanan 1 kg/cm2 yakni sebesar 88,27%.

  5. Ion transport membrane module and vessel system

    Science.gov (United States)

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

    2008-02-26

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

  6. Analysis of Protein-Membrane Interactions

    DEFF Research Database (Denmark)

    Kemmer, Gerdi Christine

    Cellular membranes are complex structures, consisting of hundreds of different lipids and proteins. These membranes act as barriers between distinct environments, constituting hot spots for many essential functions of the cell, including signaling, energy conversion, and transport. These functions...... are implemented by soluble proteins reversibly binding to, as well as by integral membrane proteins embedded in, cellular membranes. The activity and interaction of these proteins is furthermore modulated by the lipids of the membrane. Here, liposomes were used as model membrane systems to investigate...... interactions between proteins and lipids. First, interactions of soluble proteins with membranes and specific lipids were studied, using two proteins: Annexin V and Tma1. The protein was first subjected to a lipid/protein overlay assay to identify candidate interaction partners in a fast and efficient way...

  7. Amniotic membrane covering for facial nerve repair

    Institute of Scientific and Technical Information of China (English)

    Murat Karaman; Arzu Tuncel; Shahrouz Sheidaei; Mehmet Güney (S)enol; Murat Hakan Karabulut; Ildem Deveci; Nihan Karaman

    2013-01-01

    Amniotic membranes have been widely used in ophthalmology and skin injury repair because of their anti-inflammatory properties. In this study, we measured therapeutic efficacy and determined if amniotic membranes could be used for facial nerve repair. The facial nerves of eight rats were dissected and end-to-end anastomosis was performed. Amniotic membranes were covered on the anastomosis sites in four rats. Electromyography results showed that, at the end of the 3rd and 8th weeks after amniotic membrane covering, the latency values of the facial nerves covered by amniotic membranes were significantly shortened and the amplitude values were significantly increased. Compared with simple facial nerve anastomosis, after histopathological examination, facial nerve anastomosed with amniotic membrane showed better continuity, milder inflammatory reactions, and more satisfactory nerve conduction. These findings suggest that amniotic membrane covering has great potential in facial nerve repair.

  8. Genistein Modified Polymer Blends for Hemodialysis Membranes

    Science.gov (United States)

    Chang, Teng; Kyu, Thein; Define, Linda; Alexander, Thomas

    2012-02-01

    A soybean-derived phytochemical called genistein was used as a modifying agent to polyether sulfone/polyvinyl pyrrolidone (PES/PVP) blends to produce multi-functional hemodialysis membranes. With the aid of phase diagrams of PES/PVP/genistein blends, asymmetric porous membranes were fabricated by coagulating in non-solvent. Both unmodified and genistein modified PES/PVP membranes were shown to be non-cytotoxic to the blood cells. Unmodified PES/PVP membranes were found to reduce reactive oxygen species (ROS) levels, whereas the genistein modified membranes exhibited suppression for ˜60% of the ROS levels. Also, the genistein modified membranes revealed significant suppression of pro-inflammatory cytokines: IL-1β, IL-6, and TNF-α. Moreover, addition of PVP to PES showed the reduced trend of platelet adhesion and then leveled off. However, the modified membranes exhibited suppression of platelet adhesion at low genistein loading, but beyond 15 wt%, the platelet adhesion level rised up.

  9. Dialysis membrane for separation on microchips

    Science.gov (United States)

    Singh, Anup K.; Kirby, Brian J.; Shepodd, Timothy J.

    2010-07-13

    Laser-induced phase-separation polymerization of a porous acrylate polymer is used for in-situ fabrication of dialysis membranes inside glass microchannels. A shaped 355 nm laser beam is used to produce a porous polymer membrane with a thickness of about 15 .mu.m, which bonds to the glass microchannel and forms a semi-permeable membrane. Differential permeation through a membrane formed with pentaerythritol triacrylate was observed and quantified by comparing the response of the membrane to fluorescein and fluorescently tagging 200 nm latex microspheres. Differential permeation was observed and quantified by comparing the response to rhodamine 560 and lactalbumin protein in a membrane formed with SPE-methylene bisacrylamide. The porous membranes illustrate the capability for the present technique to integrate sample cleanup into chip-based analysis systems.

  10. Planar bilayer membranes from photoactivable phospholipids.

    Science.gov (United States)

    Borle, F; Sänger, M; Sigrist, H

    1991-07-22

    Planar bilayer membranes formed from photoactivable phospholipids have been characterized by low frequency voltametry. Cyclic voltametric measurements were applied for simultaneous registration of planar membrane conductivity and capacitance. The procedure has been utilized to characterize the formation and stability of planar bilayer membranes. Bilayer membranes were formed from N'-(1,2-dimyristoyl-sn-glycero-3-phosphoethyl)-N-((m-3- trifluoromethyldiazirine)phenyl)thiourea (C14-PED), a head-group photosensitive phospholipid. In situ photoactivation of C14-PED at wavelengths greater than or equal to 320 nm altered neither the mean conductivity nor the capacitance of the bilayer. Ionophore (valinomycin) and ion channel (gramicidin) activities were not impaired upon photoactivation. In contrast, bilayer membranes formed from 1,2-bis(hexadeca-2,4-dienoyl)-sn- glycero-3-phosphocholine (C16-DENPC) revealed short life times. In situ photopolymerization of the diene fatty acids significantly increased the membrane conductivity or led to membrane rupture.

  11. Photo-switchable membrane and method

    Science.gov (United States)

    Marshall, Kenneth L; Glowacki, Eric

    2013-05-07

    Switchable gas permeation membranes in which a photo-switchable low-molecular-weight liquid crystalline (LC) material acts as the active element, and a method of making such membranes. Different LC eutectic mixtures were doped with mesogenic azo dyes and infused into track-etched porous membranes with regular cylindrical pores. Photo-induced isothermal phase changes in the imbibed mesogenic material afforded large, reversible changes in the permeability of the photo-switchable membrane to nitrogen. For example, membranes imbibed with a photo-switchable cyanobiphenyl LC material demonstrated low permeability in the nematic state, while the photo-generated isotropic state demonstrated a 16.times.-greater sorption coefficient. Both states obey a high linear sorption behavior in accordance with Henry's Law. In contrast, membranes imbibed with a photo-switchable phenyl benzoate LC material showed the opposite permeability behavior to the biphenyl-imbibed membrane, along with nonlinear sorption behavior.

  12. Understanding membrane fouling mechanisms through computational simulations

    Science.gov (United States)

    Xiang, Yuan

    This dissertation focuses on a computational simulation study on the organic fouling mechanisms of reverse osmosis and nanofiltration (RO/NF) membranes, which have been widely used in industry for water purification. The research shows that through establishing a realistic computational model based on available experimental data, we are able to develop a deep understanding of membrane fouling mechanism. This knowledge is critical for providing a strategic plan for membrane experimental community and RO/NF industry for further improvements in membrane technology for water treatment. This dissertation focuses on three major research components (1) Development of the realistic molecular models, which could well represent the membrane surface properties; (2) Investigation of the interactions between the membrane surface and foulants by steered molecular dynamics simulations, in order to determine the major factors that contribute to surface fouling; and (3) Studies of the interactions between the surface-modified membranes (polyethylene glycol) to provide strategies for antifouling.

  13. Matrix Metalloproteinases Expression in Choroidal Neovascular Membranes

    Institute of Scientific and Technical Information of China (English)

    Jun Zeng; Deyong Jiang; Xiangping Liu; Xiaohua Zhu; Luosheng Tang

    2004-01-01

    Purpose: To investigate the expression of matrix metalloproteinases (MMPs) in choroidal neovascular membranes with age-related macular degeneration (AMD).Methods: Seventeen choroidal neovascular membranes surgically removed from AMD patients with pars plana vitrectomy and subretinal membranes peeling were investigated.The expression of MMP-2 and MMP-9 was determined with immunohistochemical technique.Results: Immunohistochemistry staining in choroidal neovascular membranes for MMP2 and MMP-9 was observed in 17 specimens. There was no detective of MMP-2 and MMP-9 in normal retinas.Conclusions: MMP-2 and MMP-9 were found in choroidal neovascular membranes, may degrade the Bruch membrane and be associated with the perforation of new vessels into Bruch membrane, involving a basic pathogenic process of AMD.

  14. Composite perfluorohydrocarbon membranes, their preparation and use

    Energy Technology Data Exchange (ETDEWEB)

    Ding, Yong; Bikson, Benjamin

    2017-04-04

    Composite porous hydrophobic membranes are prepared by forming a perfluorohydrocarbon layer on the surface of a preformed porous polymeric substrate. The substrate can be formed from poly (aryl ether ketone) and a perfluorohydrocarbon layer can be chemically grafted to the surface of the substrate. The membranes can be utilized for a broad range of fluid separations, such as microfiltration, nanofiltration, ultrafiltration as membrane contactors for membrane distillation and for degassing and dewatering of fluids. The membranes can further contain a dense ultra-thin perfluorohydrocarbon layer superimposed on the porous poly (aryl ether ketone) substrate and can be utilized as membrane contactors or as gas separation. membranes for natural gas treatment and gas dehydration.

  15. Advanced composite polymer electrolyte fuel cell membranes

    Energy Technology Data Exchange (ETDEWEB)

    Wilson, M.S.; Zawodzinski, T.A.; Gottesfeld, S.; Kolde, J.A.; Bahar, B.

    1995-09-01

    A new type of reinforced composite perfluorinated polymer electrolyte membrane, GORE-SELECT{trademark} (W.L. Gore & Assoc.), is characterized and tested for fuel cell applications. Very thin membranes (5-20 {mu}m thick) are available. The combination of reinforcement and thinness provides high membrane, conductances (80 S/cm{sup 2} for a 12 {mu}m thick membrane at 25{degrees}C) and improved water distribution in the operating fuel cell without sacrificing longevity or durability. In contrast to nonreinforced perfluorinated membranes, the x-y dimensions of the GORE-SELECT membranes are relatively unaffected by the hydration state. This feature may be important from the viewpoints of membrane/electrode interface stability and fuel cell manufacturability.

  16. Visualizing structural dynamics of thylakoid membranes

    Science.gov (United States)

    Iwai, Masakazu; Yokono, Makio; Nakano, Akihiko

    2014-01-01

    To optimize photosynthesis, light-harvesting antenna proteins regulate light energy dissipation and redistribution in chloroplast thylakoid membranes, which involve dynamic protein reorganization of photosystems I and II. However, direct evidence for such protein reorganization has not been visualized in live cells. Here we demonstrate structural dynamics of thylakoid membranes by live cell imaging in combination with deconvolution. We observed chlorophyll fluorescence in the antibiotics-induced macrochloroplast in the moss Physcomitrella patens. The three-dimensional reconstruction uncovered the fine thylakoid membrane structure in live cells. The time-lapse imaging shows that the entire thylakoid membrane network is structurally stable, but the individual thylakoid membrane structure is flexible in vivo. Our observation indicates that grana serve as a framework to maintain structural integrity of the entire thylakoid membrane network. Both the structural stability and flexibility of thylakoid membranes would be essential for dynamic protein reorganization under fluctuating light environments. PMID:24442007

  17. Ceramic Ultrafiltration Membrane from Nanosilica Particles

    Science.gov (United States)

    Wahid, Zarina Abdul; Ramli, Rafindde; Muchtar, Andanastuti; Mohammad, Abd Wahab

    This study attempts to develop asymmetric ceramic membrane filter from nanosilica particles for ultrafiltration (UF) membrane. The alumina tube was used as a support and was coated with SiC which acted as an intermediate layer or microfiltration (MF) layer. The UF membrane was developed using the filtration technique through chemical suspension of the particles. Nanosilica was suspended in HCl acid, iso-propanol and acetone before it was deposited on the alumina tube using a special coating assembly. The membranes were characterised for pore size, thickness and microstructure. This study found that the use of nanoparticles for membrane development could easily control the pore size as well as the thickness of the membrane. The uniformity of the membrane thickness could also be achieved through this filtration technique.

  18. Pointlike Inclusion Interactions in Tubular Membranes

    Science.gov (United States)

    Vahid, Afshin; Idema, Timon

    2016-09-01

    Membrane tubes and tubular networks are ubiquitous in living cells. Inclusions like proteins are vital for both the stability and the dynamics of such networks. These inclusions interact via the curvature deformations they impose on the membrane. We analytically study the resulting membrane mediated interactions in strongly curved tubular membranes. We model inclusions as constraints coupled to the curvature tensor of the membrane tube. First, as special test cases, we analyze the interaction between ring- and rod-shaped inclusions. Using Monte Carlo simulations, we further show how pointlike inclusions interact to form linear aggregates. To minimize the curvature energy of the membrane, inclusions self-assemble into either line- or ringlike patterns. Our results show that the global curvature of the membrane strongly affects the interactions between proteins embedded in it, and can lead to the spontaneous formation of biologically relevant structures.

  19. Interaction of Defensins with Model Cell Membranes

    Science.gov (United States)

    Sanders, Lori K.; Schmidt, Nathan W.; Yang, Lihua; Mishra, Abhijit; Gordon, Vernita D.; Selsted, Michael E.; Wong, Gerard C. L.

    2009-03-01

    Antimicrobial peptides (AMPs) comprise a key component of innate immunity for a wide range of multicellular organisms. For many AMPs, activity comes from their ability to selectively disrupt and lyse bacterial cell membranes. There are a number of proposed models for this action, but the detailed molecular mechanism of selective membrane permeation remains unclear. Theta defensins are circularized peptides with a high degree of selectivity. We investigate the interaction of model bacterial and eukaryotic cell membranes with theta defensins RTD-1, BTD-7, and compare them to protegrin PG-1, a prototypical AMP, using synchrotron small angle x-ray scattering (SAXS). The relationship between membrane composition and peptide induced changes in membrane curvature and topology is examined. By comparing the membrane phase behavior induced by these different peptides we will discuss the importance of amino acid composition and placement on membrane rearrangement.

  20. DIFFERENT APPROACHES TO CRYSTALLIZATION OF MEMBRANE PROTEINS

    Directory of Open Access Journals (Sweden)

    Prakash G. Doiphode

    2012-01-01

    Full Text Available Crystallography is more like an art than science. Crystallizing membrane proteins are a big challenge; membrane proteins are present in the cell membrane and serve as cell support. The most important feature of membrane protein is that it contains both hydrophobic and hydrophilic regions on its surface. They are generally much more difficult to study than soluble proteins. The problem becomes more difficult when trying to obtain crystals to determine the high resolution structures of membrane proteins. We want to utilize this opportunity to briefly examine various approaches for crystallization of membrane proteins. The important factors for determining the success of crystallization experiments for membrane proteins lies in the purification, preparation of membrane samples, the environment in which the crystals are grown and the technique used to grow the crystals. All the X-ray structures of membrane protein are grown from preparations of detergents by different methods developed to crystallize. In this review different techniques for the crystallization of membrane proteins are being described. The cubic phase method also known as in meso method is discussed along with other methods to understand about the crystallization of membrane proteins, its general applicability, salt, detergent and screening effects on crystallization. Low volumes as nano-liter of samples can be used for crystallization. The effects of different detergents on the crystallization of membrane protein, as well as the use of surfactants like polyoxyethylene. Approach based on the detergent complexation to prove the ability of cyclodextrins to remove detergent from ternary mixtures in order to get 2D crystals. Crystallization of membrane proteins using non-ionic surfactants as well as Lipidic sponge phase and with swollen lipidic mesophases is discussed to better understand the crystallization of membrane proteins.