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Sample records for basilar membrane

  1. Minimal basilar membrane motion in low-frequency hearing.

    Science.gov (United States)

    Warren, Rebecca L; Ramamoorthy, Sripriya; Ciganović, Nikola; Zhang, Yuan; Wilson, Teresa M; Petrie, Tracy; Wang, Ruikang K; Jacques, Steven L; Reichenbach, Tobias; Nuttall, Alfred L; Fridberger, Anders

    2016-07-26

    Low-frequency hearing is critically important for speech and music perception, but no mechanical measurements have previously been available from inner ears with intact low-frequency parts. These regions of the cochlea may function in ways different from the extensively studied high-frequency regions, where the sensory outer hair cells produce force that greatly increases the sound-evoked vibrations of the basilar membrane. We used laser interferometry in vitro and optical coherence tomography in vivo to study the low-frequency part of the guinea pig cochlea, and found that sound stimulation caused motion of a minimal portion of the basilar membrane. Outside the region of peak movement, an exponential decline in motion amplitude occurred across the basilar membrane. The moving region had different dependence on stimulus frequency than the vibrations measured near the mechanosensitive stereocilia. This behavior differs substantially from the behavior found in the extensively studied high-frequency regions of the cochlea. PMID:27407145

  2. Minimal basilar membrane motion in low-frequency hearing

    Science.gov (United States)

    Warren, Rebecca L.; Ramamoorthy, Sripriya; Ciganović, Nikola; Zhang, Yuan; Wilson, Teresa M.; Petrie, Tracy; Wang, Ruikang K.; Jacques, Steven L.; Reichenbach, Tobias; Nuttall, Alfred L.; Fridberger, Anders

    2016-01-01

    Low-frequency hearing is critically important for speech and music perception, but no mechanical measurements have previously been available from inner ears with intact low-frequency parts. These regions of the cochlea may function in ways different from the extensively studied high-frequency regions, where the sensory outer hair cells produce force that greatly increases the sound-evoked vibrations of the basilar membrane. We used laser interferometry in vitro and optical coherence tomography in vivo to study the low-frequency part of the guinea pig cochlea, and found that sound stimulation caused motion of a minimal portion of the basilar membrane. Outside the region of peak movement, an exponential decline in motion amplitude occurred across the basilar membrane. The moving region had different dependence on stimulus frequency than the vibrations measured near the mechanosensitive stereocilia. This behavior differs substantially from the behavior found in the extensively studied high-frequency regions of the cochlea. PMID:27407145

  3. 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.

  4. Modeling rapid waveform compression on the basilar membrane as multiple-bandpass-nonlinearity filtering.

    Science.gov (United States)

    Goldstein, J L

    1990-11-01

    Evidence has accumulated from experimental intracochlear studies that nonlinear mechanical response of the basilar membrane is responsible for cochlear frequency tuning and is the major source of extracochlear nonlinear phenomena in cochlear sound analysis. Known basilar-membrane data provide a basis for synthesizing and quantifying conceptions of cochlear signal processing derived earlier from extracochlear studies that indicated the existence of rapid waveform compression and dual signal processing. The multiple-bandpass-nonlinearity (MBNL) model represents and generalizes available measurements of basilar-membrane mechanical responses in terms of a rapid nonlinear mixing at each place of an insensitive, linearlike lowpass filter with a sensitive, compressive bandpass filter. The dual filters are associated with the tails and tips of cochlear frequency tuning curves. Simulations of published nonlinear mechanical responses of the basilar membrane and predicted correlations with auditory-nerve responses are systematically explored. Correlations between model and biophysical data suggest that the model represents a nonlinear mixing by outer hair cells of hydromechanical and electromechanical signals, and thus provides a quantitative tool for biophysical study of cochlear mechanisms. PMID:2292508

  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. Decoupling the level dependence of the basilar membrane gain and phase in nonlinear cochlea models.

    Science.gov (United States)

    Sisto, Renata; Moleti, Arturo; Altoè, Alessandro

    2015-08-01

    In animal experiments, the strong dependence on stimulus level of the basilar membrane gain and tuning is not matched by a corresponding change in the phase slope in the resonant region. Linear models, in which the gain dependence on the stimulus level has to be schematized by explicitly changing the tuning parameters of the resonant model, do not easily match this feature of the experimental data. Nonlinear models predict a phase slope that is relatively decoupled from tuning. In addition, delayed-stiffness and feed-forward models also show a significant intrinsic decoupling between gain and tuning, which helps in matching the experimental data. PMID:26328742

  8. 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.

  9. 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.

  10. 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....

  11. Medial olivocochlear efferent inhibition of basilar-membrane responses to clicks: Evidence for two modes of cochlear mechanical excitation

    OpenAIRE

    Guinan, John J.; Cooper, Nigel P.

    2008-01-01

    Conceptualizations of mammalian cochlear mechanics are based on basilar-membrane (BM) traveling waves that scale with frequency along the length of the cochlea, are amplified by outer hair cells (OHCs), and excite inner hair cells and auditory-nerve (AN) fibers in a simple way. However, recent experimental work has shown medial-olivocochlear (MOC) inhibition of AN responses to clicks that do not fit with this picture. To test whether this AN-initial-peak (ANIP) inhibition might result from hi...

  12. 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 ...

  13. 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.

  14. 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

    The basilar membrane input-output function (BM I/O) in a healthy cochlea is highly nonlinear. One of the consequences of sensorineural hearing loss (SNHL) is a partial or full loss of this nonlinearity. Behavioral estimates of the individual BM I/O can be useful for modeling the impaired auditory...... 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...

  15. Basilar membrane and reticular lamina motion in a multi-scale finite element model of the mouse cochlea

    Science.gov (United States)

    Soons, Joris; Dirckx, Joris; Steele, Charles; Puria, Sunil

    2015-12-01

    A multi-scale finite element (FE) model of the mouse cochlea, based on its anatomy and material properties is presented. The important feature in the model is a lattice of 400 Y-shaped structures in the longitudinal direction, each formed by Deiters cells, phalangeal processes and outer hair cells (OHC). OHC somatic motility is modeled by an expansion force proportional to the shear on the stereocilia, which in turn is proportional to the pressure difference between the scala vestibule and scala tympani. Basilar membrane (BM) and reticular lamina (RL) velocity compare qualitatively very well with recent in vivo measurements in guinea pig [2]. Compared to the BM, the RL is shown to have higher amplification and a shift to higher frequencies. This comes naturally from the realistic Y-shaped cell organization without tectorial membrane tuning.

  16. 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

  17. 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....

  18. A microelectromechanical system artificial basilar membrane based on a piezoelectric cantilever array and its characterization using an animal model

    Science.gov (United States)

    Jang, Jongmoon; Lee, Jangwoo; Woo, Seongyong; Sly, David J.; Campbell, Luke J.; Cho, Jin-Ho; O'Leary, Stephen J.; Park, Min-Hyun; Han, Sungmin; Choi, Ji-Wong; Hun Jang, Jeong; Choi, Hongsoo

    2015-07-01

    We proposed a piezoelectric artificial basilar membrane (ABM) composed of a microelectromechanical system cantilever array. The ABM mimics the tonotopy of the cochlea: frequency selectivity and mechanoelectric transduction. The fabricated ABM exhibits a clear tonotopy in an audible frequency range (2.92-12.6 kHz). Also, an animal model was used to verify the characteristics of the ABM as a front end for potential cochlear implant applications. For this, a signal processor was used to convert the piezoelectric output from the ABM to an electrical stimulus for auditory neurons. The electrical stimulus for auditory neurons was delivered through an implanted intra-cochlear electrode array. The amplitude of the electrical stimulus was modulated in the range of 0.15 to 3.5 V with incoming sound pressure levels (SPL) of 70.1 to 94.8 dB SPL. The electrical stimulus was used to elicit an electrically evoked auditory brainstem response (EABR) from deafened guinea pigs. EABRs were successfully measured and their magnitude increased upon application of acoustic stimuli from 75 to 95 dB SPL. The frequency selectivity of the ABM was estimated by measuring the magnitude of EABRs while applying sound pressure at the resonance and off-resonance frequencies of the corresponding cantilever of the selected channel. In this study, we demonstrated a novel piezoelectric ABM and verified its characteristics by measuring EABRs.

  19. Transfection of hTERT into newborn rat cochlear basilar membrane cells%hTERT转染永生化新生大鼠耳蜗基底膜细胞的研究

    Institute of Scientific and Technical Information of China (English)

    许映龙; 刘晖; 王军利; 许珉

    2012-01-01

    目的 通过基因转染法获得新生大鼠耳蜗基底膜细胞永生化细胞系.方法 通过脂质体法将pCI-neo-hTERT质粒转染原代培养的新生大鼠耳蜗基底膜细胞,G418筛选获得稳定转染的细胞系,并行转染细胞RT-PCR、端粒酶活性、细胞周期、细胞凋亡等检测.结果 转染72h后RT-PCR检测到人端粒酶逆转录酶(hTERT)基因阳性表达,转染细胞通过G418筛选传代后,可检测到端粒酶活性,流式细胞术检测提示转染细胞增殖活力增强不明显,但细胞凋亡明显减少.结论 通过脂质体转染hTERT基因,可使新生大鼠耳蜗基底膜细胞凋亡减少,传代能力增强,给耳蜗细胞实验提供足够的细胞来源.%Objective To obtain immortalized cell lines of newborn rat cochlear basilar membrane cells through gene transfection method. Methods Rat cochlear basilar membrane cells were grown in primary culture. pCI-neo-hTERT plasmid was transfected into the cells. Stably transfected cell lines were screened with G418. RT-PCR, telomerase activity detection, cell cycle and apoptosis detection were used to evaluate the effects. Results Human telomerase reverse transcriptase (hTERT) gene expression could be detected by RT-PCR 72 hours after transfection. The stably transfected cell lines were obtained by screening with G418; the telomerase activity of hTERT-transfected cells could be detected. Flow cytometry detection showed that hTERT could slightly improve cell vitality, but significantly reduce cell apoptosis. Conclusion Transferring hTERT gene into newborn rat cochlear basilar membrane cells can reduce cell apoptosis and improve cell passage ability, which provides enough cell sources for cochlear cell experiments.

  20. 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.

  1. 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.

  2. Hyperdensity of the Basilar Artery on Postmortem CT: A Potential Indicator for Basilar Artery Thrombosis.

    Science.gov (United States)

    Garland, Jack; Tse, Rexson; Beh, Raymond J; Lyons, Timothy J; Cala, Allan D

    2016-06-01

    Basilar artery thrombosis constitutes 1% of all types of stroke, carries a mortality rate of up to 90%, and is one of the rarer causes of sudden death. It leads to brain stem ischemia and commonly presents with impaired consciousness, cranial nerve palsy, hemiplegia or quadriplegia, and sudden collapse. Clinically, the diagnosis of basilar artery thrombosis is made on clinical symptoms, along with a hyperdense basilar artery in antemortem computed tomography (CT) scan. To our knowledge, whether a hyperdense basilar artery indicates basilar artery thrombosis on postmortem CT scan is not documented in the literature. We present a case report of a 55-year-old man who on postmortem CT scan showed a hyperdense basilar artery and was subsequently confirmed to be a fatal basilar artery thrombosis. We suggest that a hyperdense basilar artery on postmortem CT should prompt the pathologist to consider basilar artery thrombosis. PMID:27049662

  3. Noise-Induced Alteration in Apoptosis Inducing Factor (AIF) Expression along Cochlear Basilar Membrane in Rats%噪声对大鼠耳蜗基底膜凋亡诱导因子表达的影响

    Institute of Scientific and Technical Information of China (English)

    武瑾; 崔勇; 施泽涛; 邱建华

    2013-01-01

      目的探讨噪声暴露前后凋亡诱导因子(AIF)在大鼠不同回基底膜外毛细胞的表达差异以及与噪声性聋高频听力易损性的关系。方法40只SD大鼠随机分为正常对照组和噪声暴露组:噪声暴露组给予声强为115dB SPL白噪声暴露,每天2小时,连续3天,对照组不予噪声暴露。分别于噪声暴露前1日、暴露后1、3、7、14日对两组大鼠行ABR检测,最后一次ABR检测后对两组大鼠耳蜗基底膜行鬼笔环肽—异硫氰酸荧光素(Phalloidin-FITC)染色。West-ern blot和免疫荧光染色法观察两组大鼠耳蜗不同回基底膜处AIF的表达。结果大鼠噪声暴露后与暴露前相比,ABR各频反应阈值于暴露后1天最高,随时间逐渐恢复,14天时趋于稳定,听力低频阈移约10dB,高频阈移有30dB (P<0.05);基底膜铺片FITC染色示噪声暴露组底回基底膜毛细胞较顶回缺失严重,且有纤毛排列紊乱并出现融合,而对照组毛细胞排列整齐,纤毛呈V或W型,两组间外毛细胞计数比较差异有统计学意义(P<0.05);Western blot结果示,在正常情况下,顶回基底膜的AIF表达高于底回,噪声暴露后,AIF顶、底回基底膜表达均较对照组相应部位增高,且顶回较底回更为显著(P<0.05)。结论噪声暴露过程中,AIF在促凋亡的同时更发挥出了氧化还原酶的作用,因而AIF在耳蜗基底膜顶、底回的表达差异,可能是噪声性聋高频听力易损性的分子机制之一。%Objective To Investigate differences in expression of apoptosis-inducing factor (AIF) in outer hair cells along the basilar membrane before and after noise exposure, and its potential relationship with vulnerability of high-frequen-cy hearing in noise-induced hearing loss. Methods Forty adult Sprague-Dawley (SD) rats were randomly divided into a con-trol and a noise-exposure group:animals in the noise-exposure group were exposed to white noise at 115

  4. Management of basilar invagination: A historical perspective

    Directory of Open Access Journals (Sweden)

    Abhidha Shah

    2016-01-01

    Full Text Available For a long time the terms basilar invagination and platybasia were used interchangeably. Basilar invagination has been defined as a prolapse of the vertebral column into the spinal cord. Platybasia is defined as an abnormal obtuse angle between the anterior skull base and the clivus. The authors review the existing literature and summarize the historical and modern perspectives in the management of basilar invagination. From radiological curiosities, the subject of basilar invagination is now viewed as eminently treatable. The more pronounced understanding of the subject has taken place in the last three decades when on the basis of understanding of the biomechanical subtleties the treatment paradigm has remarkably altered. From surgery that involved decompression of the region, stabilization and realignment now form the basis of treatment.

  5. Delayed treatment of basilar thrombosis in a patient with a basilar aneurysm: a case report

    Directory of Open Access Journals (Sweden)

    Fakhouri T

    2008-11-01

    Full Text Available Abstract Introduction Acute occlusion of the basilar artery is a neurological emergency that has a high risk of severe disability and mortality. Delayed thrombolysis or endovascular therapy has been performed with some success in patients who present after 3 hours of symptom onset. Here we present the first case of delayed intra-arterial thrombolysis of a basilar artery thrombosis associated with a large saccular aneurysm. Case presentation A 73-year-old Caucasian man with a history of smoking and alcohol abuse presented to the Emergency Department complaining of diplopia and mild slurred speech and who progressed over 12 hours to coma and quadriparesis. He was found to have a large basilar tip aneurysm putting him at high risk for hemorrhage with lytic treatment. Conclusion The treatment options for basilar thrombosis are discussed. Aggressive treatment options should be considered despite long durations of clinical symptoms in basilar thrombosis, even in extremely high risk patients.

  6. 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...

  7. 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.

  8. Direct clipping of large basilar trunk aneurysm.

    Science.gov (United States)

    Kimura, Toshikazu; Nakagawa, Daichi; Kawai, Kensuke

    2015-01-01

    A large basilar trunk aneurysm was incidentally found in a 77-year-old woman in examination for headache. Though it was asymptomatic, high signal intensity was noticed in the brainstem around the aneurysm on FLAIR image of MRI. As she was otherwise healthy, surgical clipping was performed through anterior temporal approach. The video can be found here: http://youtu.be/0soWM8meCW8 . PMID:25554839

  9. From basilar artery dolichoectasia to basilar artery aneurysm: natural history in images.

    Science.gov (United States)

    Zis, Panagiotis; Fragkis, Stylianos; Lykouri, Maria; Bageris, Ioannis; Kolovos, Georgios; Angelidakis, Panagiotis; Tavernarakis, Antonios

    2015-05-01

    Dolichoectasia is a medical term used to describe elongated and dilated vessels that follow a tortuous and windy course with frequent loops and curves. We are presenting the natural history in images of a normal basilar artery becoming dolichoectatic, followed by the formation of an aneurysm, over a period of many years, in 60-year-old Caucasian man with a long history of secondary progressive multiple sclerosis and uncontrolled arterial hypertension, who was diagnosed with dolichoectasia of basilar artery in 2008. Although relatively stable at this point, eventually his mobility deteriorated and signs from the cranial nerves, such as trigeminal neuralgia and bilateral palsy of the VI and the VII nerves were added in the clinical picture. In 2014, both computed tomography and magnetic resonance imaging of the brain revealed the formation of an unruptured aneurysm of the basilar artery. PMID:25765208

  10. 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

  11. 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

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

    Directory of Open Access Journals (Sweden)

    Maurus Marques de Almeida Holanda

    2015-01-01

    Full Text Available 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.

  13. Basilar Artery Aneurysm at a Persistent Trigeminal Artery Junction

    Science.gov (United States)

    Aguiar, G.B.; Conti, M.L.M.; Veiga, J.C.E.; Jory, M.; Souza, R.B.

    2011-01-01

    Summary The trigeminal artery is an anastomosis between the embryonic precursors of the vertebrobasilar and carotid systems, and may persist into adult life. The association of the persistent primitive trigeminal artery (PTA) with cerebral aneurysm is well documented in the literature and, in general, aneurysms are located in the anterior circulation. We describe a patient who presented with a panencephalic Fisher III subarachnoid hemorrhage due to rupture of an intracranial aneurysm. Digital arteriography showed a saccular aneurysm in the middle third of the basilar artery, adjacent to the junction with a persistent trigeminal artery. She was submitted to endovascular treatment with embolization of the basilar artery aneurysm with coils. Aneurysms at the PTA junction with the basilar artery are rare. This paper describes a case of PTA associated with an aneurysm in the basilar artery at PTA junction and briefly reviews the literature. PMID:22005697

  14. Basilar artery fenestration - correlative MRI and neurosonographic study

    International Nuclear Information System (INIS)

    The aim of the study is to demonstrate a rare case of congenital basilar artery fenestration using neuroimaging methods. A 58-year-old man with an isolated lesion of the right n. oculomotorius was examined with brain MRI/MRA and multimodal neurosonography. A typical fenestration was detected on MRA in the proximal portion of the basilar artery immediately after the fusion of the vertebral arteries, it was correlated with ultrasound pattern - a parallel blood flow image and retrograde flow velocity curves were obtained from the fenestrated segments of a. basilaris. Imaging (MRI/MPA and ultrasonic) methods are useful for non-invasive diagnosis of basilar artery fenestration, which in the past was proved only by conventional cerebral angiography or autopsy. (authors) Key words: Fenestration. Basilar Artery. MRI. NEUROSONOGRAPHY

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

    OpenAIRE

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

    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 an...

  16. Light-induced basilar membrane vibrations in the sensitive cochlea

    Science.gov (United States)

    Grosh, Karl; Ren, Tianying; He, Wenxuan; Fridberger, Anders; Li, Yizeng; Nankali, Amir

    2015-12-01

    The exceptional sensitivity of mammalian hearing organ is attributed to an outer hair cell-mediated active process, where forces produced by sensory cells boost sound-induced vibrations, making soft sounds audible. This process is thought to be local, with each section of the hearing organ capable of amplifying sound-evoked movement, and nearly instantaneous, since amplification can work for sounds at frequencies up to 100 kHz in some species. To test these precepts, we developed a method for focally stimulating the living hearing organ with light. Light pulses caused intense and highly damped mechanical responses followed by traveling waves that developed with considerable delay. The delayed response was identical to movements evoked by click-like sounds. A physiologically based mathematical model shows that such waves engage the active process, enhancing hearing sensitivity. The experiments and the theoretical analysis show that the active process is neither local nor instantaneous, but requires mechanical waves traveling from the cochlear base toward its apex.

  17. Predicting outcome after acute basilar artery occlusion based on admission characteristics.

    NARCIS (Netherlands)

    Greving, J.P.; Schonewille, W.J.; Wijman, C.A.; Michel, P.; Kappelle, L.J.; Algra, A.; Leeuw, F.E. de

    2012-01-01

    OBJECTIVE: To develop a simple prognostic model to predict outcome at 1 month after acute basilar artery occlusion (BAO) with readily available predictors. METHODS: The Basilar Artery International Cooperation Study (BASICS) is a prospective, observational, international registry of consecutive pati

  18. 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.

  19. 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.)

  20. 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.

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

    International Nuclear Information System (INIS)

    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.)

  2. Basilar artery thrombosis in the setting of antiphospholipid syndrome

    OpenAIRE

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

    2014-01-01

    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.

  3. 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

  4. 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.

  5. Basilar artery aneurysm with autonomic features: an interesting pathophysiological problem

    OpenAIRE

    Giffin, N; Goadsby, P

    2001-01-01

    Unruptured cerebral aneurysms often present with neuro-ophthalmological symptoms but ocular autonomic involvement from an aneurysm of the posterior circulation has not previously been reported. A patient is described with a basilar artery aneurysm presenting with headache and unilateral autonomic symptoms. After angiographic coiling of the aneurysm there was a near complete resolution of these features. The relevant anatomy and proposed mechanism of autonomic involvement of what may be ...

  6. 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

    injury caused a lesion of the right vertebral artery, leading to repeated transient ischemic attacks and finally to a fatal basilar thrombotic embolus. We suggest that in patients with disturbances of the vertebrobasilar circulation, attention should be paid to occurrence of neck trauma in the preceding...... 3 months. Further, anticoagulant therapy should particularly be considered in patients who after suffering neck injuries develop signs of transient ischemic attacks with origin from the posterior cerebral circulation....

  7. Local Intra-Arterial Fibrinolysis in Acute Basilar Artery Occlusion

    OpenAIRE

    Enomoto, Y.; Yoshimura, S.; Kitajima, H.; Tamakawa, N.; Iwama, T

    2007-01-01

    Acute basilar artery (BA) occlusion is typically associated with poor outcome; however newer diagnostic and treatment modalities have the potential to improve prognosis. In this study, six patients with acute BA occlusion were followed and the effectiveness of local intra-arterial fibrinolysis (LIF) and subsequent percutaneous transluminal angioplasty (PTA) with a balloon catheter were assessed. Of the six patients with BA occlusion observed in this study, two had extended brain stem infarcti...

  8. Intra-arterial thrombolysis in basilar artery occlusions combination of intra-arterial thrombolytics and Gp IIb/IIIa inhibitors in basilar artery thrombosis

    Directory of Open Access Journals (Sweden)

    Gaikwad S

    2009-01-01

    Full Text Available Basilar artery thrombosis has high morbidity and mortality. Though intra-arterial thrombolytics have proven efficacy in the treatment of acute basilar artery occlusion, the elevation of procoagulant factors in the blood after intra-arterial thrombolysis could result in subsequent thrombus formation and clinical deterioration. Glycoprotein IIb/IIIa inhibitors have been shown to reduce this elevation in procoagulants. We present a pilot study of three cases of acute basilar artery occlusion treated with a combination of intra-arterial thrombolytics and Gp IIb/IIIa inhibitor with remarkable clinical recovery seen in all the patients.

  9. 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.

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

    International Nuclear Information System (INIS)

    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

  11. 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.)

  12. Neurofibromatosis, stroke and basilar impression: case report Neurofibromatose, acidente vascular cerebral e impressão basilar: relato de caso

    Directory of Open Access Journals (Sweden)

    ELCIO JULIATO PIOVESAN

    1999-06-01

    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.A neurofibromatose tipo 1 (NF1 pode acometer qualquer órgão mas as apresentações mais frequente são manchas café com leite e neurofibromas. O envolvimento de vasos é complicação conhecida da NF1, mas a doença cerebrovascular é rara. Relatamos o caso de paciente do sexo masculino de 51 anos com história de acidente vascular cerebral há quatro meses da admissão. Ao exame físico apresentava várias manchas café com leite e neurofibromas cutâneos. O exame neurológico demonstrou acometimento facial direito, hemiplegia direita e afasia. Tomografia computadorizada de crânio mostrou áreas hipodensas nos gânglios basais e centros semi-ovais. Radiografias do crânio e coluna cervical

  13. 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.

  14. 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...

  15. 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.

  16. 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.

  17. 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

    basilar and middle cerebral arteries using quantitative real-time PCR (Polymerase Chain Reaction) and Western blotting, respectively. In the perfusion system, we found no significant responses after luminal application of three K(ATP) channel openers to rat basilar and middle cerebral arteries......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......, we studied the possible involvement of endothelial K(ATP) channels by pressurized arteriography after luminal administration of synthetic K(ATP) channel openers to rat basilar and middle cerebral arteries. Furthermore, we examined the mRNA and protein expression profile of K(ATP) channels to rat...

  18. Basilar artery aneurysm at a persistent trigeminal artery junction. A case report and literature review.

    Science.gov (United States)

    Aguiar, G B; Conti, M L M; Veiga, J C E; Jory, M; Souza, R B

    2011-09-01

    The trigeminal artery is an anastomosis between the embryonic precursors of the vertebrobasilar and carotid systems, and may persist into adult life. The association of the persistent primitive trigeminal artery (PTA) with cerebral aneurysm is well documented in the literature and, in general, aneurysms are located in the anterior circulation. We describe a patient who presented with a panencephalic Fisher III subarachnoid hemorrhage due to rupture of an intracranial aneurysm. Digital arteriography showed a saccular aneurysm in the middle third of the basilar artery, adjacent to the junction with a persistent trigeminal artery. She was submitted to endovascular treatment with embolization of the basilar artery aneurysm with coils. Aneurysms at the PTA junction with the basilar artery are rare. This paper describes a case of PTA associated with an aneurysm in the basilar artery at PTA junction and briefly reviews the literature. PMID:22005697

  19. 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......, we studied the possible involvement of endothelial K(ATP) channels by pressurized arteriography after luminal administration of synthetic K(ATP) channel openers to rat basilar and middle cerebral arteries. Furthermore, we examined the mRNA and protein expression profile of K(ATP) channels to rat...... basilar and middle cerebral arteries using quantitative real-time PCR (Polymerase Chain Reaction) and Western blotting, respectively. In the perfusion system, we found no significant responses after luminal application of three K(ATP) channel openers to rat basilar and middle cerebral arteries. In...

  20. An Unusual Cause of Pediatric Stroke Secondary to Congenital Basilar Artery Fenestration

    OpenAIRE

    Gold, J. J.; Crawford, J R

    2013-01-01

    Basilar artery fenestration is an uncommon congenital variant that has been associated with aneurysms and posterior circulation infarcts in the adult literature. Little is known about the functional consequences of basilar artery fenestration, if any, in childhood. We present a case of a previously healthy 12-year-old boy who presented with diplopia, tinnitus, and ataxia who had subtle findings on diffusion-weighted magnetic resonance imaging consistent with posterior circulation territory in...

  1. Apoptosis of endothelial cells of cerebral basilar arteries in symptomatic cerebral vasospasm rabbit models Electron microscopic observation

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    microscope, samples were stained with lead citrate uranyl acetate staining, observed with electron microscope and photographed.MAIN OUTCOME MEASURES: Morphological changes of cytoplasm and nucleus of vascular endothelial cells and smooth muscle cells in the two groups.RESULTS: Morphology of vascular endothelial cells in cerebral basilar artery was not changed in the control group. However, vascular endothelial cells in the experimental group showed that cytochondria were swelling; endocytoplasmic reticulum was amplified; chromatin margination was clear; nucleus was in pyknosis; endothelial cells fell down from basal membrane; cell-cell junction was broken. Changes of smooth muscle cells were similar to those of endothelial cells. Severely, it was shown that nuclear pyknosis was obvious, and this was like early apoptosis.CONCLUSION: Apoptosis of endothelial cells may occur in spasmodic vessels.

  2. 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.

  3. Numerical simulations of post-surgical flow and thrombosis in basilar artery aneurysms

    Science.gov (United States)

    Seshadhri, Santhosh; Lawton, Michael; Boussel, Loic; Saloner, David; Rayz, Vitaliy

    2015-11-01

    Surgical treatment of basilar artery aneurysms presents a major challenge since it is crucial to preserve the flow to the vital brainstem perforators branching of the basilar artery. In some cases, basilar aneurysms can be treated by clipping vessels in order to induce flow reduction and aneurysm thrombosis. Patient-specific CFD models can provide guidance to clinicians by simulating postoperative flows resulting from alternative surgeries. Several surgical options were evaluated for four basilar aneurysm patients. Patient-specific models were generated from preoperative MR angiography and MR velocimetry data and modified to simulate different procedures. The Navier-Stokes equations were solved with a finite-volume solver Fluent. Virtual contrast injections were simulated by solving the advection-diffusion equation in order to estimate the flow residence time and determine thrombus-prone regions. The results indicated on procedures that reduce intra-aneurysmal velocities and flow regions which are likely to become thrombosed. Thus CFD modeling can help improve the outcome of surgeries altering the flow in basilar aneurysms.

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

    International Nuclear Information System (INIS)

    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 signs of

  5. '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.

  6. Experimental study of physiological flow in a cerebral saccular basilar tip aneurysm

    Science.gov (United States)

    Tsai, William; Savas, Omer; Ortega, Jason; Maitland, Duncan; Saloner, David

    2008-11-01

    The subject matter of the research is the flow within cerebral saccular basilar tip aneurysms and exploring correlations with their growth and rupture. The flow phantom consists of an inlet pipe branching out 90^o into two outlets, simulating the basilar artery bifurcation and a nearly spherical dome at the flow divider simulating the aneurysm. Input flow is a physiological waveform for the basilar artery. Flow outlet branching ratios are controlled at will. Experiments are done at Reynolds numbers 221-376 and Sexl-Wormersley number 4.46. Flow visualization and particle image velocimetry are used to study velocity, vorticity, and wall shear stress. All flows can be characterized by an off-center inlet jet and a circulation region, whose transient strength and behavior depends on the outflow ratios.

  7. Three-dimensional fusion angiography of a giant basilar aneurysm for coil embolization

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Joo Yeon; Suh, Dae Chul [Dept. of Radiology and Research Institute of Radiology, University of Ulsan College of Medicine, Asan Medical Center, Seoul (Korea, Republic of)

    2015-05-15

    A giant aneurysm was unexpectedly found on computed tomography angiogram in a 54-year-old female. Cerebral angiogram showed a giant aneurysm at the ventral side of the lower basilar artery trunk. However, it was difficult to demonstrate the precise relationship between the aneurysmal sac and the parent artery because of the incomplete filling of the contrast medium secondary to the preferential flows from a well-balanced development of both vertebral arteries. Three-dimensional (3D) fusion angiography revealed complete filling of the aneurysm as well as the basilar trunk itself beyond the aneurysm, which was dysplastic. Coiling of the aneurysm was safely and completely accomplished based on the fusion images. In this report, we demonstrate a case of giant basilar aneurysm with 3D fusion angiography proving useful in assisting with treatment planning.

  8. 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.

  9. 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.

  10. Pontine capillary telangiectasia as visualized on MR imaging causing a clinical picture resembling basilar-type migraine: a case report

    OpenAIRE

    Beukers, R.J.; Roos, Y.B.W.E.M.

    2009-01-01

    A case of presumed pontine capillary telangiectasia in an 18-year-old woman with a clinical diagnosis of basilar-type migraine is reported. Since both are very rare diagnoses, this case provides some evidence to suggest that pontine capillary telangiectasia might cause a clinical picture resembling basilar-type migraine.

  11. Bilateral Stenosis of the Internal carotid artery , associated with aneurysm of the basilar trunk

    Directory of Open Access Journals (Sweden)

    A.A. MORSHED

    1975-01-01

    Full Text Available I A case of bilateral stenosis of the internal carotid artery with aneurysm"nof basilar trunk is reported."n2 Via femoral angiography confirmed the diagnosis which is strongly"nrecommended in diagnosing such cases."n3 No surgica l treatment is considered."n4 No similar case has been reported in literature.

  12. Unusual persistent primitive trigeminal artery with a superior duplicated basilar system.

    Science.gov (United States)

    Mohammad, Laila Malani; Carlson, Andrew Phillip

    2016-07-01

    A 67-year-old patient who presented with a right cerebellar hemorrhage underwent vascular workup for suspicion of underlying vascular anomalies. A diagnostic cerebral angiogram demonstrated a duplicated basilar system fed solely by a persistent primitive trigeminal artery. The findings proved to be incidental and unrelated to the patient's hemorrhage. These developmental abnormalities are consistent with embryological development. PMID:26404778

  13. 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

  14. 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

  15. 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

  16. Experience of Y-Configured Stents for Small Basilar Tip Aneurysms

    OpenAIRE

    Cho, Chun-Sung; Kim, Young-Joon; Kim, Jin Kyung; Kim, Young Jin; Lee, Sang Koo; Cho, Maeng Ki

    2007-01-01

    Among posterior circulation aneurysms, basilar tip aneurysm is the most difficult to treat. Because of their deep location in front of the brain-stem and their intimate relationship to perforating vessels, morbidity and mortality rates associated with direct exposure used to be daunting.

  17. 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.

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

    International Nuclear Information System (INIS)

    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.

  19. 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 t...

  20. Mechanism of nicotine-induced relaxation in the porcine basilar artery

    DEFF Research Database (Denmark)

    Zhang, W; Edvinsson, L; Lee, T J

    1998-01-01

    The present experiment was designed to examine possible influence of adrenergic nerves on nicotine-induced neurogenic vasodilation in porcine basilar arteries denuded of endothelium. Nicotine and transmural nerve stimulation (TNS) induced relaxation of basilar arteries. Tetrodotoxin (TTX) abolished...... the relaxation elicited by TNS, but only partially blocked that induced by nicotine. Relaxation induced by both nicotine and TNS was abolished by N-nitro-L-arginine. The N-nitro-L-arginine inhibition of both TNS- and nicotine-induced relaxation was reversed by L-arginine but not by D-arginine. Hexamethonium...... abolished the relaxation induced by nicotine, but did not affect that elicited by TNS. Relaxation induced by nicotine was diminished by guanethidine, which did not affect the relaxation induced by TNS, suggesting that guanethidine blockade of nicotine-induced relaxation is not due to its local anesthetic...

  1. [Intra-arterial thrombolysis of a basilar vascular accident during coronary angiography].

    Science.gov (United States)

    Battikh, K; Rihani, R; Lemahieu, J M; Mokahal, M; Houchaymi, Z; Cornaert, P; Dutoit, A

    2001-09-01

    The authors report the case of a 67 year old man with a previous history of aortobifemoral arterial graft who had unstable angina after carotid endarterectomy. Coronary angiography by the right brachial artery was complicated by a cerebrovascular accident with a reactive coma, convulsions and respiratory problems. Selective angiography of the right vertebral artery showed an image of occlusive thrombosis of the basilar artery. In view of the clinical state and angiographic appearances, the authors decided on immediate intra-arterial thrombolysis with Urokinase which dissolved the clot and reestablished flow in the basilar artery, the cerebellar and posterior cerebral arteries. The outcome was favourable with immediate and good recovery of consciousness and hospital discharge on the sixth day without neurological or radiological sequellae. Cerebrovascular accident is a rare and potentially serious complication of left heart catheterisation which requires immediate cerebral angiography to determine the mechanism and propose an appropriate therapeutic approach. PMID:11603067

  2. 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.

  3. Involvement of protein kinases on the upregulation of endothelin receptors in rat basilar and mesenteric arteries

    DEFF Research Database (Denmark)

    Jamali, Roya; Edvinsson, Lars

    2006-01-01

    were determined with a real-time polymerase chain reaction (PCR). The cellular localization and protein level of ET(B) receptors were evaluated by immunohistochemistry. The PKC and ERK1/2 inhibitors attenuated the contraction induced by S6c in the basilar arteries more than in the mesenteric arteries....... Immunohistochemistry revealed that the ET(B) receptor upregulation occured in the smooth-muscle cells and that it had the same pattern as in the quantitative PCR. Our results show that the PKC, ERK1/2, and JNK are more important for the upregulation of contractile ET(B) receptors in cerebral arteries compared...... of protein kinases (c-Jun N-terminal kinase [JNK], protein kinase C [PKC], and extracellular signal-regulated kinase [ERK1/2]) in ET(B) receptor upregulation after organ culture. Rat basilar and mesenteric arteries were incubated for 24 hrs in Dulbecco's modified Eagle's medium (DMEM) with or without the PKC...

  4. Hyperdense basilar artery as a CT sign of basilar artery thrombosis; Hyperdense Basilararterie in der Computertomographie als Hinweis auf eine Basilaristhrombose

    Energy Technology Data Exchange (ETDEWEB)

    Jaeger, H.J.; Gissler, H.M.; Hennigs, S.; Mathias, K.D. [Staedtische Kliniken Dortmund (Germany). Roentgeninstitut und Strahlenklinik; Dittmar, G. [Witten-Herdecke Univ., Witten (Germany). Lehrstuhl fuer Radiologie und MikroTherapie

    2000-07-01

    With growing acceptance of systemic and local thrombolysis as a novel treatment for stroke patients, early detection of cerebral ischemia or infarction has become a priority task in initial clinical examination, with CT being the method of primary significance in this context, as most of the patients first of all are examined by CT in the acute post-stroke phase, and the thrombolytic therapy is applicable within a time window of a only a few hours. The case report describes the diagnostic procedure adopted in response to neurological findings and CT results showing a hyperdense basilar artery, so that thrombosis of the basilar artery was suspected. A local intraarterial fibrinolysis (LIF) was performed immediately, and the thrombosis could be removed successfully. (orig./CB) [German] Mit dem Aufkommen der systemischen und lokalen Thrombolyse als neue Therapieform fuer die Behandlung des Schlaganfalls, hat die Frueherkennung einer Hirnischaemie bzw. eines Hirninfarktes eine wichtige Bedeutung bekommen. Der CT kommt in diesem Zusammenhang ein besonderer Stellenwert zu, da die meisten Patienten im akuten Stadium zunaechst mit der CT untersucht werden und bei der thrombolytischen Therapie ein sehr enges in Stunden zu messendes Zeitfenster gilt. Wir berichten ueber einen Fall, bei dem aufgrund des neurologischen Befundes und einer hyperdensen Basilararterie in der CT die Verdachtsdiagnose einer Thrombose der Basilarspitze gestellt wurde. Eine sofort durchgefuehrte lokale intraarterielle Lysetherapie (LIF) fuehrte zur erfolgreichen Lyse des thrombotischen Verschlusses der Basilarisspitze. (orig.)

  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. 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.

  7. 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.

  8. 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.

  9. 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.

  10. Flow diverter as a rescue therapy for a complicated basilar angioplasty.

    Science.gov (United States)

    Velioglu, Murat; Ozturk, Ersin; Sonmez, Guner; Kendirli, Tansel; Mutlu, Hakan; Basekim, Cinar

    2013-01-01

    Intracranial atherosclerotic disease is a major cause of ischemic stroke. Stenting and aggressive medical management for preventing recurrent stroke in intracranial stenosis was terminated prematurely due to a high stroke and death rate in patients randomized for intracranial stent placement. However, for some patients, angioplasty and/or stent placement remains the best approach. Flow diverters (FDs) are designed to produce a hemodynamic flow diversion by constituting a laminar flow pattern in the parent artery and are mainly used in non-ruptured complex wide-neck aneurysms as well as in ruptured aneurysms. Herein, we present a case where an FD was used in a complicated angioplasty for basilar artery atherosclerosis. A 72-year-old female patient was admitted to our hospital with left side weakness and vertigo. Her diffusion magnetic resonance imaging and magnetic resonance angiography showed right-sided pontine and left-sided occipital acute infarcts with left-sided pontine and right-sided occipital chronic infarcted areas and preocclusive mid-basilar stenosis. The patient was under supervised medical treatment. Despite chronic brain stem and occipital infarcts her modified Rankin Scale was 2. Diagnostic angiography showed no posterior communicating arteries and no pial-pial collaterals and a critical mid-basilar artery stenosis. We decided to perform intracranial angioplasty to increase the perfusion of posterior circulation and reduce the risk of additional embolic infarcts. Angioplasty was complicated with dissection and vessel perforation. We used an FD for rescue therapy to avoid rebleeding. The patient was discharged with good clinical and angiographic results.

  11. Fronto-temporo-orbitozygomatic craniotomy and "half-and-half" approach for basilar apex aneurysms

    Directory of Open Access Journals (Sweden)

    Behari Sanjay

    2009-01-01

    Full Text Available Background: Basilar apex aneurysms (BAA are located in interpeduncular cistern surrounded by eloquent neurovascular structures. Surgical access is difficult due to narrow surgical corridors and requires traversing through a depth of 6-8 cm of subarachnoid space. Aim: Surgical management of BAAs clipped using frontotemporal craniotomy, orbitozygomatic osteotomy with combined subtemporal and transylvian (half and half approach is discussed. Setting and Design: Tertiary care referral institute; prospective study. Materials and Methods: Five patients with BAA rupture causing subarachnoid hemorrhage presented in modified Hunt and Hess (Hand H grades II (n=1, III (n=1 and IV (n=3, respectively. In 4 patients, the aneurysms were 0.8-1.2 cm in diameter, situated 7 mm-1 cm above dorsum sellae. Two of them had posteriorly projecting aneurysms. One patient had a giant, high BAA with a left parietooccipital arteriovenous malformation. Vasospasm of posterior cerebral/proximal basilar artery was seen in 2 patients. In one patient, internal carotid artery was mobilized by intradural anterior clinoid drilling with carotid collar division. Triple-H therapy was administered following surgery. Results: There was no intraoperative rupture or temporary clipping. Follow up angiography showed complete aneurysmal obliteration with preservation of posterior cerebral and superior cerebellar arteries. Follow up (mean: 8.7 ± 3.5 months H and H grades were II (n=2 and III (n=3, respectively. The morbidity include caudate and thalamic region infarct, transient III rd nerve palsy and cerebrospinal fluid otorrhoea (n=1, respectively. Conclusions: This simple approach provides a wide surgical corridor from 5 mm below to greater than 1 cm above dorsum sellae with adequate proximal control of basilar artery. It is an option to endovascular embolization especially with large and giant, or wide-necked BAA, vertebrobasilar tortuosity, coil compaction or postcoiling re-rupture and

  12. Stent treatment for basilar artery dissection: A single-center experience of 21 patients.

    Science.gov (United States)

    Li, Li; Li, Tianxiao; Xue, Jiangyu; Wang, Ziliang; Bai, Weixing; Zhu, Liangfu; Feng, Guang; Xu, Gangqin; Yang, Bowen

    2016-06-01

    Basilar artery dissection is a rare disease with high morbidity and mortality. No well-established management strategy exists for this lesion. Endovascular reconstructive therapy using stents (with or without coiling) may be the optimum strategy.We describe our center's experience for this treatment strategy in 21 patients with basilar artery dissection from January 2009 to July 2014 (17 men, four women; age range, 18-70 years; median age, 56 years). We divided patients into two groups: Group 1 patients received stent-assisted coiling treatment, and Group 2 patients received stent-only treatment. Pre-treatment, peri-operation and follow-up evaluation were investigated for complications, clinical outcome and angiographic results. The median follow-up time was 20 months (range, 3-67 months).All patients were treated endovascularly by stent-assisted coiling (14 patients) or stent only (seven patients). Immediate angiography showed: in Group 1, five of 14 lesions were completely occluded, five were partially occluded, four revealed retention of contrast media; in Group 2, all patients (seven of seven) had contrast retention. At the follow-up visit (median seven months, 3-29 months), the aneurysms were angiographically improved in five of 13 patients in Group 1 compared with immediately post-operation, while six of sevenimproved in Group 2. Five patients (all in Group 1) had ischemic or hemorrhage peri-operation complications. Long-term good clinical outcomes (modified Rankin Scale score (mRS) ≤ 2) were achieved in all patients except three death cases (two in Group1, one in Group 2).In our experience, endovascular reconstructive therapy using stents (with or without coiling) for basilar artery dissection is effective and safe. Stent-only treatment seems have a better safety profile during the peri-operation period. PMID:26842610

  13. Posterior cerebral artery angle and the rupture of basilar tip aneurysms.

    Directory of Open Access Journals (Sweden)

    Allen L Ho

    Full Text Available Since the initial publication of the International Study of Unruptured Intracranial Aneurysms (ISUIA, management of unruptured intracranial aneurysms has been mainly based on the size of the aneurysm. The contribution of morphological characteristics to treatment decisions of unruptured aneurysms has not been well studied in a systematic and location specific manner. We present a large sample of basilar artery tip aneurysms (BTA that were assessed using a diverse array of morphological variables to determine the parameters associated with ruptured aneurysms. Demographic and clinical risk factors of aneurysm rupture were obtained from chart review. CT angiograms (CTA were evaluated with Slicer, an open source visualization and image analysis software, to generate 3-D models of the aneurysms and surrounding vascular architecture. Morphological parameters examined in each model included aneurysm volume, aspect ratio, size ratio, aneurysm angle, basilar vessel angle, basilar flow angle, and vessel to vessel angles. Univariate and multivariate analyses were performed to determine statistical significance. From 2008-2013, 54 patients with BTA aneurysms were evaluated in a single institution, and CTAs from 33 patients (15 ruptured, 18 unruptured were available and analyzed. Aneurysms that underwent reoperation, that were associated with arteriovenous malformations, or that lacked preoperative CTA were excluded. Multivariate logistic regression revealed that a larger angle between the posterior cerebral arteries (P1-P1 angle, p = 0.037 was most strongly associated with aneurysm rupture after adjusting for other morphological variables. In this location specific study of BTA aneurysms, the larger the angle formed between posterior cerebral arteries was found to be a new morphological parameter significantly associated with ruptured BTA aneurysms. This is a physically intuitive parameter that can be measured easily and readily applied in the clinical

  14. 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. PMID:26063795

  15. 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.

  16. Intrathecal injection of human umbilical cord blood-derived mesenchymal stem cells for the treatment of basilar artery dissection: a case report

    Directory of Open Access Journals (Sweden)

    Han Hoon

    2011-12-01

    Full Text Available Abstract Introduction Basilar artery dissection is a rare occurrence, and is significantly associated with morbidity and mortality. To the best of our knowledge, we report the first case of basilar artery dissection treated with mesenchymal stem cells. Case presentation We present the case of a 17-year-old Korean man who was diagnosed with basilar artery dissection. Infarction of the bilateral pons, midbrain and right superior cerebellum due to his basilar artery dissection was partially recanalized by intrathecal injection of human umbilical cord blood-derived mesenchymal stem cells. No immunosuppressants were given to our patient, and human leukocyte antigen alloantibodies were not detected after cell therapy. Conclusions This case indicates that intrathecal injections of mesenchymal stem cells can be used in the treatment of basilar artery dissection.

  17. '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.

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

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    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.

  19. [A case of basilar impression treated with mandible splitting transoral approach].

    Science.gov (United States)

    Young-Su, P; Ishikawa, J; Matsumoto, M; Sato, T; Owaki, H

    1997-05-01

    We report a case of basilar impression treated with mandible splitting transoral approach surgery. A 39-year-old man presented a ten-year history of gait disturbance. He had experienced acceleration of his spastic paraparesis for the past few years. Neurological examination on admission demonstrated tetraparesis (MMT4/5), severe hyperreflexia in his arms and legs, severe sensory loss below C2, urinary retention and inability to open his mouth widely. Radiological findings showed the dens and the body of C2 are deeply invaginated to the atlas and the foramen magnum and medulla and upper cervical cord were markedly compressed by this basilar invagination. After carrying out posterior decompression and occipito-cervical fixation, we attempted to remove the invaginated dens and the C2 vertebral body using a conventional transoral approach. But limitation of mouth opening made operative fields narrow. Consequently because of insufficient anterior decompression his neurological deficits could not be alleviated. Employment of mandible splitting procedure brought about a wide operative view so that complete removal of the residual dens and 70% drilling out of the C2 body was made possible. Postoperative complications were negligible. Finally, great alleviation of his deficits was achieved. Mandible splitting procedure is effective for obtaining a wide operative field on the anterior approach to the craniocervical junction. PMID:9145409

  20. 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.

  1. Pontine capillary telangiectasia as visualized on MR imaging causing a clinical picture resembling basilar-type migraine: a case report

    NARCIS (Netherlands)

    R.J. Beukers; Y.B.W.E.M. Roos

    2009-01-01

    A case of presumed pontine capillary telangiectasia in an 18-year-old woman with a clinical diagnosis of basilar-type migraine is reported. Since both are very rare diagnoses, this case provides some evidence to suggest that pontine capillary telangiectasia might cause a clinical picture resembling

  2. 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

  3. 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%.

  4. Endovascular treatment of acute basilar artery occlusion: time to treatment is crucial

    International Nuclear Information System (INIS)

    Aim: To evaluate the safety and efficacy of multimodal endovascular treatment (EVT) of acute basilar artery occlusion (BAO), including bridging therapy [intravenous thrombolysis (IVT) with subsequent EVT], to compare particular EVT techniques and identify predictors of clinical outcome. Materials and methods: This retrospective, multi-centre study comprised 72 acute ischaemic stroke patients (51 males; mean age 59.1 ± 13.3 years) with radiologically confirmed BAO. The following data were collected: baseline characteristics, risk factors, pre-event antithrombotic treatment, neurological deficit at time of treatment, localization of occlusion, time to therapy, recanalization rate, post-treatment imaging findings. Thirty- and 90-day outcomes were evaluated using the modified Rankin scale with a good clinical outcome defined as 0–3 points. Results: Successful recanalization was achieved in 94.4% patients. Stepwise binary logistic regression analysis identified the presence of arterial hypertension (OR = 0.073 and OR = 0.067, respectively), National Institutes of Health Stroke Scale (NIHSS) at the time of treatment (OR = 0,829 and OR = 0.864, respectively), and time to treatment (OR = 0.556 and OR = 0.502, respectively) as significant independent predictors of 30- and 90-day clinical outcomes. Conclusion: Data from this multicentre study showed that multimodal EVT was an effective recanalization method in acute BAO. Bridging therapy shortens the time to treatment, which was identified as the only modifiable outcome predictor. - Highlights: • Various treatments are being used in recanalization of basilar artery occlusion. • Multimodal endovascular treatment is an effective recanalization method. • Time-to-treatment is the only modifiable outcome predictor. • Bridging therapy shortens time-to-treatment. • Arterial hypertension, neurologic deficit are associated with poor outcome

  5. Unusual Intracranial Stent Navigation through the Circle of Willis in a Patient with Recurrent Basilar Tip Aneurysm during Stent-Assisted Coiling: A Case Report

    OpenAIRE

    Puri, A.S.; Erdem, E.

    2009-01-01

    We describe a case of unusual Enterprise stent navigation through the Circle of Willis in a patient with a basilar tip aneurysm, left internal carotid artery (ICA) occlusion and previous right ICA stenting. Basilar tip aneurysms are known for their therapeutic challenges, especially when the posterior cerebral arteries (PCAs) are incorporated in the aneurysm neck. This becomes more technically demanding if the vertebral artery does not offer a route for stent navigation.

  6. Molecular investigations of BK(Ca) channels and the modulatory beta-subunits in porcine basilar and middle cerebral arteries

    DEFF Research Database (Denmark)

    Johansson, Helle Wulf; Hay-Schmidt, Anders; Poulsen, Asser Nyander;

    2009-01-01

    arteries using reverse transcription polymerase chain reaction (RT-PCR) and quantitative real-time PCR. Western blotting was used to detect immunoreactivity for the porcine BK(Ca) channel alpha-subunit and beta-subunit proteins. The BK(Ca) channel alpha-subunit RNA and protein distribution patterns were...... visualized using in situ hybridization and immunofluorescence studies, respectively. The study verified that the BK(Ca) channel alpha-subunit is located to smooth muscle cells of porcine basilar and middle cerebral arteries. The mRNA transcript for beta1-, beta2- and beta4-subunit were shown by RT-PCR...... in porcine basilar and middle cerebral arteries. However, at the protein level, only, the beta1-subunit protein was found by western blotting....

  7. 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.

  8. Successful Coil Embolization of a Ruptured Basilar Artery Aneurysm in a Child with Leukemia: A Case Report

    OpenAIRE

    HAYASHI, Shihori; Maehara, Taketoshi; Mukawa, Maki; Aoyagi, Masaru; YOSHINO, Yoshikazu; NEMOTO, Shigeru; Ono, Toshiaki; Ohno, Kikuo

    2013-01-01

    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 mome...

  9. Pontine infarction caused by medial branch injury of the basilar artery as a rare complication of cisternal drain placement

    OpenAIRE

    Horiuchi, Tetsuyoshi; Yamamoto, Yasunaga; Kuroiwa, Masafumi; Rahmah, Nunung Nur; Hongo, Kazuhiro

    2012-01-01

    We present a rare complication of cisternal drain placement during aneurysm surgery. A ruptured anterior communicating artery aneurysm was clipped through a right pterional approach. A cisternal drain was inserted from the retro-carotid to the prepontine cistern. Postoperatively, a left-sided paresis of the upper extremity had developed. A CT brain scan revealed that the drain was located between the pons and the basilar artery, resulting in a pontine infarction. Vascular neurosurgeons should...

  10. Characterization of histamine receptors in isolated pig basilar artery by functional and radioligand binding studies

    International Nuclear Information System (INIS)

    Histamine receptors in pig basilar arteries were investigated in vitro by radioligand binding assays and by measuring the contractile and relaxant responses to histamine. Histamine and 2-pyridyethylamine (H1-agonist) induced concentration-dependent contractions, whereas impromidine (H2-agonist) induced concentration-dependent relaxations. These responses were independent of the presence of endothelial cells. Diphenhydramine (H1-antagonist) partially reversed the histamine-induced contractions to relaxations. Cimetidine (Hα2-antagonist) potentiated the contraction in a concentration-dependent manner. In the presence of cimetidine, the pEC50 value of histamine for the contraction was 6.30, and diphenhydramine competitively antagonized the histamine-induced contractions (pA2, 7.77). In the presence of diphenhydramine, the pEC50 value of histamine for the relaxation was 5.93, and cimetidine competitively antagonized the histamine-induced relaxations (pA2, 6.62). In the binding studies, the Kd value of [3H]mepyramine was 2.1 nM and the Bmax value was 95.6 fmol/mg protein. A competition experiment with diphenhydramine showed that the pKi value (7.51) was similar to the pA2 value. The Kd value for [3H]cimetidine was 126.0 nM and the Bmax value was 459.8 fmol/mg protein. The pKd (6.90) for [3H]cimetidine was similar to the pA2 for cimetidine. The Hill coefficients for these experiments were not significantly different from unity. The present findings indicate that the number of H1-receptors, in terms of the Bmax value for [3H]mepyramine, is smaller than that of H2-receptors, in terms of the Bmax value for [3H]cimetidine. However, the contractile response to histamine is predominantly mediated through stimulation of H1-receptors on vascular smooth muscle cells in pig basilar artery

  11. Basilar expansion of the human sphenoidal sinus: an integrated anatomical and computerized tomography study

    International Nuclear Information System (INIS)

    Basilar expansion of the sphenoidal sinus (BESS) was studied in order to demonstrate its critical relevance in endoscopic or microscopic endonasal surgical interventions, including access to the sphenoidal sinus itself or in transsphenoidal pituitary approaches. Direct evaluation of anatomical specimens (25 dry skulls and 25 formalin-fixed hemi heads) and the use of computerized tomography (CT) (50 dry skulls and 750 patients) showed a high BESS frequency (69%). The authors considered BESS to be critical when the posterior wall of the clivus was 2-mm thick and found a high incidence of this important anatomical variation (44%). This study also evaluated the relationship between the sinonasal septa, the clivus, and the internal carotid arteries, and a considerable regularity in the location of these structures was seen. The septa were anatomically related to the internal carotid arteries in 55% and to the clivus in 33% of the cases. In conclusion, the high frequency of critical BESS here described is relevant to endoscopic or microscopic endonasal surgical interventions, including access to the sphenoidal sinus itself or in transsphenoidal pituitary approaches. (orig.)

  12. Persistent Neutrophilic Meningitis in an Immunocompetent Patient after Basilar Skull Fracture: Case Report

    Directory of Open Access Journals (Sweden)

    Uslan Daniel Z

    2011-05-01

    Full Text Available Abstract Background Persistent neutrophilic meningitis is an unusual form of chronic meningitis that is defined as clinical meningitis with a neutrophilic pleocytosis that persists for greater than 7 days despite empiric antimicrobial therapy. Although numerous disease processes can cause this syndrome, the majority of cases are due to opportunistic pathogens infecting immunocompromised hosts. Case Presentation A 47 year-old female presented after basilar skull fracture with persistent neutrophilic meningitis unresponsive to empiric broad-spectrum antibiotics. After more than weeks of intensive therapy, 4 hospitalizations and 3 relapses, Nocardia cyriacigeorgica was identified from cerebral spinal fluid. Induction therapy was begun with Ceftriaxone and trimethoprim-sulfamethoxazole (TMP-SMX for 6 weeks followed by therapy with TMP-SMX and doxycycline for one year. The patient made a complete recovery without sequelae. Conclusions Due to the difficulty in obtaining a microbiologic diagnosis, appropriate treatment in cases of persistent neutrophilic meningitis is often delayed leading to morbidity, This case highlights a number of the unique features of Nocardia meningitis and the importance of considering Nocardia infection as a cause of persistent neutrophilic meningitis even in immunocompetent patients.

  13. 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.)

  14. The odontoid process invagination in normal subjects, Chiari malformation and Basilar invagination patients: Pathophysiologic correlations with angular craniometry

    Science.gov (United States)

    Ferreira, Jânio A.; Botelho, Ricardo V.

    2015-01-01

    Background: Craniometric studies have shown that both Chiari malformation (CM) and basilar invagination (BI) belong to a spectrum of malformations. A more precise method to differentiate between these types of CVJM is desirable. The Chamberlain's line violation (CLV) is the most common method to identify BI. The authors sought to clarify the real importance of CLV in the spectrum of craniovertebral junction malformations (CVJM) and to identify possible pathophysiological relationships. Methods: We evaluated the CLV in a sample of CVJM, BI, CM patients and a control group of normal subjects and correlated their data with craniocervical angular craniometry. Results: A total of 97 subjects were studied: 32 normal subjects, 41 CM patients, 9 basilar invagination type 1 (BI1) patients, and 15 basilar invagination type 2 (BI2) patients. The mean CLV violation in the groups were: The control group, 0.16 ± 0.45 cm; the CM group, 0.32 ± 0.48 cm; the BI1 group, 1.35 ± 0.5 cm; and the BI2 group, 1.98 ± 0.18 cm. There was strong correlation between CLV and Boogard's angle (R = 0.82, P = 0.000) and the clivus canal angle (R = 0.7, P = 0.000). Conclusions: CM's CLV is discrete and similar to the normal subjects. BI1 and BI2 presented with at least of 0.95 cm CLV and these violations were strongly correlated with a primary cranial angulation (clivus horizontalization) and an acute clivus canal angle (a secondary craniocervical angle). PMID:26229733

  15. Acute ischemic stroke in a child due to basilar artery occlusion treated successfully with a stent retriever.

    Science.gov (United States)

    Savastano, Luis; Gemmete, Joseph J; Pandey, Aditya S; Roark, Christopher; Chaudhary, Neeraj

    2016-08-01

    Ischemic strokes in childhood are rare. Thrombolytic therapy with intravenous (IV) tissue plasminogen activator (tPA) has been the main intervention for the management of pediatric stroke patients, but safety data are lacking and efficacy has been questioned. Recently, successful endovascular treatments for acute ischemic stroke in children have been reported with increasing frequency, suggesting that mechanical thrombectomy can be a safe and effective treatment. We present the case of a 22-month-old child with acute ischemic stroke due to basilar artery occlusion that was successfully treated with a stent retriever. PMID:26156170

  16. Contrast Extravasation on Computed Tomography Angiography Imitating a Basilar Artery Trunk Aneurysm in Subsequent Conventional Angiogram-Negative Subarachnoid Hemorrhage: Report of Two Cases with Different Clinical Courses.

    Science.gov (United States)

    Cho, Won Ho; Choi, Hyuk Jin; Nam, Kyoung Hyup; Lee, Jae Il

    2015-12-01

    Contrast extravasation on computed tomography angiography (CTA) is rare but becoming more common, with increasing use of CTA for various cerebral vascular diseases. We report on two cases of spontaneous subarachnoid hemorrhage (SAH) in which the CTA showed an upper basilar trunk saccular lesion suggesting ruptured aneurysm. However, immediate subsequent digital subtraction angiography (DSA) failed to show a vascular lesion. In one case, repeated follow up DSA was also negative. The patient was treated conservatively and discharged without any neurologic deficit. In the other case, the patient showed sudden mental deterioration on the third hospital day and her brain CT showed rebleeding. The immediate follow up DSA showed contrast stagnation in the vicinity of the upper basilar artery, suggestive of pseudoaneurysm. Double stents deployment at the disease segment was performed. Due to the frequent use of CTA, contrast extravasation is an increasingly common observation. Physicians should be aware that basilar artery extravasation can mimic the appearance of an aneurysm. PMID:27066442

  17. 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.

  18. Congenital Absence of Posterior Elements of C2 Vertebra with Atlanto-Axial Dislocation and Basilar Invagination: A Case Report and Review of Literature.

    Science.gov (United States)

    Srivastava, Sudhir Kumar; Nemade, Pradip Sharad; Aggarwal, Rishi Anil; Bhoale, Sunil Krishna

    2016-02-01

    Developmental anomalies of the axis are commonly encountered, especially anomalies involving the odontoid process. Anomalies of the posterior elements are uncommon. We describe a unique case of agenesis of posterior elements of C2 with basilar invagination and atlanto-axial dislocation. An obese 8-year-old boy presented with symptoms of cervical myelopathy. Radiological workup revealed a craniovertebral junction anomaly with occipitalised atlas, absent posterior elements of axis, and hypertrophied C3 spinous process. Atlanto-axial instability and basilar invagination was present. Magnetic resonance angiography revealed hypoplastic left vertebral artery. Traction with cervical tongs failed to improve the alignment and symptoms. Anterior trans-oral release, followed by posterior decompression and custom-made instrumentation, was done. The patient recovered completely and was asymptomatic at the end of two years. X-ray and computed tomography scan demonstrated reduction of basilar invagination and maintenance of alignment. This is the first case to be reported of agenesis of posterior elements of axis associated with basilar invagination. One should look for this condition in patients with hypertrophied spinous process of C3. Utilization of hypoplastic pedicle of axis serves as an additional fixation point to increase the stability of the construct. PMID:26949474

  19. Oligosymptomatic and giant basilar artery dolichoectasia discovered after a stroke: case report Dolicoectasia gigante e oligossintomática da artéria basilar descoberta após uma isquemia: relato de caso

    Directory of Open Access Journals (Sweden)

    Cynthia Resende Campos

    2007-06-01

    Full Text Available The most frequently diagnosed complication of vertebrobasilar dolichoectasia (VBD is the compression of structures adjacent to the vertebral and basilar arteries. A giant VBD with only slight compressive symptoms is unusual. In this setting, the diagnosis of VBD may be casually revealed after the occurrence of a posterior circulation stroke, another potential complication. We report a 48-year-old woman who presented a two-month history of continuous buzz and a slight right-sided hearing loss that was followed by a cerebellar ischemic stroke. Brain CT and MRI revealed a marked compression of the brainstem due to an ectatic, tortuous and partially thrombosed basilar artery (BA. The largest cross-sectional diameter of BA was 18 mm. The patient had a good functional recovery within the two-month follow-up after stroke with modified Rankin scale score (mRSS=2. At the one-year follow-up, patient still kept the complaints of continuous buzz, slight right-sided hearing loss and the mRSS was the same. We call attention for an unusual giant VBD that caused an impressive brainstem compression with displacement of important structures in an oligosymptomatic patient. Diagnosis was made only after the occurrence of a stroke. Despite of the good functional recovery after stroke, the presence of significant atherosclerotic changes and the large BA diameter may indicate a poor outcome. However, after one year, she remains oligosymptomatic.A complicação mais freqüentemente encontrada na dolicoectasia vertebrobasilar (DVB é a compressão de estruturas adjacentes às artérias vertebrais e à artéria basilar. Uma DVB gigante apenas com sintomas compressivos leves é infreqüente. Nesse caso, o diagnóstico pode ser descoberto ao acaso após uma isquemia da circulação posterior, outra complicação possível da DVB. Relatamos o caso de uma mulher de 48 anos com história de zumbido e perda auditiva leve a direita por 2 meses, desenvolvendo, a seguir, uma

  20. 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.

  1. 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.

  2. 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.

  3. Emergency Use of Stent and rtPA with Mechanical Cloth Defragmentation for a Thromboembolic Complication during GDC Coil Treatment of an Acutely Ruptured Basilar Tip Aneurysm.

    Science.gov (United States)

    Poncyljusz, W; Falkowski, A; Kojder, I; Sagan, L

    2006-11-30

    Thrombotic occlusion of both posterior cerebral arteries occurred during embolization of an acutely ruptured basilar tip aneurysm. Intracranial stenting and continuous superselective infusion of rtPA was administered combined with mechanical clot fragmentation to reestablish normal vessel flow. DSA disclosed that normal vessel patency was achieved within 30 min. There were no adverse events related to rtPA administration and the patient recovered from the embolization with minor neurologic deficit as present before the procedure. PMID:24351269

  4. 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

  5. Contrast Extravasation on Computed Tomography Angiography Imitating a Basilar Artery Trunk Aneurysm in Subsequent Conventional Angiogram-Negative Subarachnoid Hemorrhage: Report of Two Cases with Different Clinical Courses

    OpenAIRE

    Cho, Won Ho; Choi, Hyuk Jin; Nam, Kyoung Hyup; Lee, Jae Il

    2015-01-01

    Contrast extravasation on computed tomography angiography (CTA) is rare but becoming more common, with increasing use of CTA for various cerebral vascular diseases. We report on two cases of spontaneous subarachnoid hemorrhage (SAH) in which the CTA showed an upper basilar trunk saccular lesion suggesting ruptured aneurysm. However, immediate subsequent digital subtraction angiography (DSA) failed to show a vascular lesion. In one case, repeated follow up DSA was also negative. The patient wa...

  6. Contrast Extravasation on Computed Tomography Angiography Imitating a Basilar Artery Trunk Aneurysm in Subsequent Conventional Angiogram-Negative Subarachnoid Hemorrhage: Report of Two Cases with Different Clinical Courses

    OpenAIRE

    Cho, Won Ho; Choi, Hyuk Jin; Nam, Kyoung Hyup; Lee, Jae Il

    2015-01-01

    Contrast extravasation on computed tomography angiography (CTA) is rare but becoming more common, with increasing use of CTA for various cerebral vascular diseases. We report on two cases of spontaneous subarachnoid hemorrhage (SAH) in which the CTA showed a saccular lesion of the upper basilar trunk suggesting a ruptured aneurysm. However, no vascular lesion was observed on immediate subsequent digital subtraction angiography (DSA). In one case, repeated follow up DSA was also negative. The ...

  7. 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.

  8. 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. .

  9. 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.

  10. 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

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    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

  11. 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...

  12. 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.

  13. 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

  14. 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.)

  15. 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....

  16. 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

  17. 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

  18. 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

  19. 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.

  20. 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.

  1. 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.

  2. Application of CT angiography in the diagnosis of persistent carotid-basilar artery anastomoses%永存颈内-基底动脉吻合的CTA诊断

    Institute of Scientific and Technical Information of China (English)

    赵海玲; 王之平; 王君松

    2012-01-01

    目的:探讨16层螺旋CT血管成像(CTA)在永存颈内-基底动脉吻合诊断中的价值,提高对此类血管变异的认识.方法:回顾性分析1951例行颅脑及颅颈联合CTA检查发现的的10例永存动脉[永存三叉动脉(PTA)8例,永存舌下动脉(PHA)2例]患者的影像学资料,分析永存动脉的发生率、CTA表现及合并其他脑血管异常的情况.结果:PTA的发生率为0.41%(8/1951).PHA的发生率为0.10%(2/1951).PTA均起自颈内动脉海绵窦段,按Saltzman分型显示后循环供血情况:Ⅰ型4例,Ⅱ型3例,Ⅲ型1例.2例PHA分别于C1、C2水平从颈内动脉发出,均向后内弯曲穿过扩大的同侧舌下神经管,与基底动脉形成吻合,吻合处下方的基底动脉萎缩,后交通动脉缺如.PTA吻合口下方基底动脉和(或)椎动脉发育不良2例;PTA合并同侧颈内动脉发育不良、同侧大脑前动脉交通前段发育不良1例;PTA合并烟雾病及其侧枝血管动脉瘤形成1例.PHA合并基底动脉末端动脉瘤1例.结论:16层螺旋CTA能清晰显示永存颈内-基底动脉吻合及其合并的脑血管异常情况,并可根据动脉结构与形态间接评估其血流动力学特征,对外科手术及介入治疗有一定的指导作用.%Objective:To discuss the value of 16 slice spiral CT angiography (CTA) in the diagnosis of persistent ca rotid basilar artery anastomoses,in an effort to improve the understanding of this vascular variation. Methods:The CTA ma terials of 1951 cases having cerebral and neck CTA were reviewed. Of them,10 patients had persistent carotid basilar artery anastomoses [8 patients with persistent trigeminal artery (PTA) ,2 patients with persistent hypoglossar artery (PHA)]. The incidence rate,CTA findings and the complication with other cerebral vascular abnormalities were analyzed retrospec tively. Results:The incidence of PTA was 0.41% (8/1951),of PHA was 0.10% (2/1951). All of the PTA originated from the cavernous segment of internal carotid

  3. Membrane Processes.

    Science.gov (United States)

    Pellegrin, Marie-Laure; Sadler, Mary E; Greiner, Anthony D; Aguinaldo, Jorge; Min, Kyungnan; Zhang, Kai; Arabi, Sara; Burbano, Marie S; Kent, Fraser; Shoaf, Robert

    2015-10-01

    This review, for literature published in 2014, contains information related to membrane processes for municipal and industrial applications. This review is a subsection of the Treatment Systems section of the annual Water Environment Federation literature review and covers the following topics: pretreatment, membrane bioreactor (MBR) configuration, design, nutrient removal, operation, industrial treatment, fixed film and anaerobic membrane systems, reuse, microconstituents removal, membrane technology advances, membrane fouling, and modeling. Other sub-sections of the Treatment Systems section that might relate to this literature review include: Biological Fixed-Film Systems, Activated Sludge and Other Aerobic Suspended Culture Processes, Anaerobic Processes, Water Reclamation and Reuse. The following sections might also have related information on membrane processes: Industrial Wastes, Hazardous Wastes, and Fate and Effects of Pollutants. PMID:26420079

  4. Membrane Processes.

    Science.gov (United States)

    Pellegrin, Marie-Laure; Burbano, Marie S; Sadler, Mary E; Diamond, Jason; Baker, Simon; Greiner, Anthony D; Arabi, Sara; Wong, Joseph; Doody, Alexandra; Padhye, Lokesh P; Sears, Keith; Kistenmacher, Peter; Kent, Fraser; Tootchi, Leila; Aguinaldo, Jorge; Saddredini, Sara; Schilling, Bill; Min, Kyungnan; McCandless, Robert; Danker, Bryce; Gamage, Neranga P; Wang, Sunny; Aerts, Peter

    2016-10-01

    This review, for literature published in 2015, contains information related to membrane processes for municipal and industrial applications. This review is a subsection of the Treatment Systems section of the annual Water Environment Federation literature review and covers the following topics: pretreatment, membrane bioreactor (MBR) configuration, design, nutrient removal, operation, industrial treatment, anaerobic membrane systems, reuse, microconstituents removal, membrane technology advances, membrane fouling, and modeling. Other sub-sections of the Treatment Systems section that might relate to this literature review include: Biological Fixed-Film Systems, Activated Sludge and Other Aerobic Suspended Culture Processes, Anaerobic Processes, Water Reclamation and Reuse. The following sections might also have related information on membrane processes: Industrial Wastes, Hazardous Wastes, and Fate and Effects of Pollutants. PMID:27620084

  5. 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.

  6. 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.

  7. 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

    to hypercapnia. L-NOARG and MB, but not TTX, significantly reduced the basal cGMP content in cerebral vessels. Adding 1.5% halothane to the incubation medium did not result in a significant increase in cGMP content. Lowering the pH by cumulative application of 0.12 M HCl resulted in relaxation identical...... to that obtained by lowering the pH with 15% CO2. In vessel segments in which the endothelium had been removed beforehand 15% CO2 induced relaxation that was not different from that seen in vessels with intact endothelium. L-NOARG had no affect in endothelium denuded vessels. The results suggest that high CO2...... elicits vasodilatation of isolated rat basilar arteries by a mechanism independent of nitric oxide synthase (NOS) activity. The markedly reduced basal cGMP levels in cerebral vessels by L-NOARG and MB suggest that there exists a basal NO formation in the cerebral vessel wall....

  8. Acute Ischemic Stroke Involving Both Anterior and Posterior Circulation Treated by Endovascular Revascularization for Acute Basilar Artery Occlusion via Persistent Primitive Trigeminal Artery

    Science.gov (United States)

    Fujita, Atsushi; Hosoda, Kohkichi; Kohmura, Eiji

    2016-01-01

    We report a case of acute ischemic stroke involving both the anterior and posterior circulation associated with a persistent primitive trigeminal artery (PPTA), treated by endovascular revascularization for acute basilar artery (BA) occlusion via the PPTA. An otherwise healthy 67-year-old man experienced sudden loss of consciousness and quadriplegia. Magnetic resonance imaging showed an extensive acute infarction in the right cerebral hemisphere, and magnetic resonance angiography showed occlusion of the right middle cerebral artery (MCA) and BA. Because the volume of infarction in the territory of the right MCA was extensive, we judged the use of intravenous tissue plasminogen activator to be contraindicated. Cerebral angiography revealed hypoplasia of both vertebral arteries and the presence of a PPTA from the right internal carotid artery. A microcatheter was introduced into the BA via the PPTA and revascularization was successfully performed using a Merci Retriever with adjuvant low-dose intraarterial urokinase. After treatment, his consciousness level and right motor weakness improved. Although persistent carotid-vertebrobasilar anastomoses such as a PPTA are relatively rare vascular anomalies, if the persistent primitive artery is present, it can be an access route for mechanical thrombectomy for acute ischemic stroke. PMID:27446523

  9. Acute Ischemic Stroke Involving Both Anterior and Posterior Circulation Treated by Endovascular Revascularization for Acute Basilar Artery Occlusion via Persistent Primitive Trigeminal Artery.

    Science.gov (United States)

    Imahori, Taichiro; Fujita, Atsushi; Hosoda, Kohkichi; Kohmura, Eiji

    2016-07-01

    We report a case of acute ischemic stroke involving both the anterior and posterior circulation associated with a persistent primitive trigeminal artery (PPTA), treated by endovascular revascularization for acute basilar artery (BA) occlusion via the PPTA. An otherwise healthy 67-year-old man experienced sudden loss of consciousness and quadriplegia. Magnetic resonance imaging showed an extensive acute infarction in the right cerebral hemisphere, and magnetic resonance angiography showed occlusion of the right middle cerebral artery (MCA) and BA. Because the volume of infarction in the territory of the right MCA was extensive, we judged the use of intravenous tissue plasminogen activator to be contraindicated. Cerebral angiography revealed hypoplasia of both vertebral arteries and the presence of a PPTA from the right internal carotid artery. A microcatheter was introduced into the BA via the PPTA and revascularization was successfully performed using a Merci Retriever with adjuvant low-dose intraarterial urokinase. After treatment, his consciousness level and right motor weakness improved. Although persistent carotid-vertebrobasilar anastomoses such as a PPTA are relatively rare vascular anomalies, if the persistent primitive artery is present, it can be an access route for mechanical thrombectomy for acute ischemic stroke. PMID:27446523

  10. Diagnosis of vertebral basilar artery variation with digital subtraction angiography%应用 DSA 诊断椎-基底动脉变异

    Institute of Scientific and Technical Information of China (English)

    王金龙; 张鸿祺; 焦力群; 朱凤水; 李慎茂; 吉训明; 凌锋

    2014-01-01

    目的:探讨椎基底动脉变异的种类和发生率及DSA影像学特征,提高对椎基底动脉变异临床意义的认识。方法对6432例患者均进行全脑血管进行造影,对全脑血管造影的DSA图像资料进行回顾性分析,得出椎基底动脉变异的发生率及变异血管合并其他血管病变的情况。结果发生椎动脉起源变异272例患者278支椎动脉,检出率为4.3%,其中左椎动脉起源异常270支(4.2%),右椎动脉起源异常8支;左椎动脉起源异常中,258支直接起自主动脉弓,2例为双起源椎动脉,4支起自颈内动脉,6支起自左锁骨下动脉根部。8支右椎动脉起源异常中,2支直接起源于右颈总动脉,2支起自右颈内动脉动脉,2例为双起源椎动脉,2支直接起自头臂干动脉。141例椎基底动脉成窗(2.19%);61支小脑后下动脉起自颅外段位置较低部位。11例永久性原始三叉动脉。另外,有9例变异结构的远端或近端伴发动脉瘤、2例伴发动静脉畸形。7例出现与成窗结构供血区相一致的一过性脑缺血症状,其中2例出现经成窗结构远端供血部位的脑梗塞,1例出现经双起源椎动脉供血部位的脑梗塞。结论脑血管DSA可以清晰显示椎基底动脉变异的位置、形态、毗邻关系及有无伴发其他血管性病变;掌握椎基底动脉变异的DSA影像学表现及血流动力学特征,对脑血管病的明确诊断及手术和介入治疗方案的制定具有重要临床意义。%Objective This study is to investigate the prevalence of vertebral basilar artery veriation and its imaging char-acters in patients receiving cerebral artery digital subtraction angiography .Methods We reviewed 6432 patients receiving cerebral artery digital subtraction angiography ,and got the prevalence of vertebral basilar artery veriation and associated cerebral artery diseases in these patients .Results Among the 6432 patients ,4

  11. 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...

  12. 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

  13. 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.

  14. 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.

  15. 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.

  16. Omniphobic Membrane for Robust Membrane Distillation

    Energy Technology Data Exchange (ETDEWEB)

    Lin, SH; Nejati, S; Boo, C; Hu, YX; Osuji, CO; Ehmelech, M

    2014-11-01

    In this work, we fabricate an omniphobic microporous membrane for membrane distillation (MD) by modifying a hydrophilic glass fiber membrane with silica nanoparticles followed by surface fluorination and polymer coating. The modified glass fiber membrane exhibits an anti-wetting property not only against water but also against low surface tension organic solvents that easily wet a hydrophobic polytetrafluoroethylene (PTFE) membrane that is commonly used in MD applications. By comparing the performance of the PTFE and omniphobic membranes in direct contact MD experiments in the presence of a surfactant (sodium dodecyl sulfate, SDS), we show that SDS wets the hydrophobic PTFE membrane but not the omniphobic membrane. Our results suggest that omniphobic membranes are critical for MD applications with feed waters containing surface active species, such as oil and gas produced water, to prevent membrane pore wetting.

  17. The imaging and clinical significance of persistent carotid-basilar artery anastomoses%永存颈内-基底动脉吻合的影像学特点及其意义

    Institute of Scientific and Technical Information of China (English)

    袁飞; 崔翔; 刘银社; 赵军; 顾欣

    2011-01-01

    目的 探讨永存颈内-基底动脉吻合的影像学特点,提高对此类异常吻合血管的认识。方法回顾性分析12例经头颈CT血管造影(CTA)及MR血管造影(MRA)诊断为永存颁内-基底动脉吻合患者的影像学资料。其中9例病人行头颈联合CTA检查,3例行头和/或颈部MR血管造影(MRA)检查。结果12例中,9例为永存三叉动脉,3例为永存舌下动脉。永存三叉动脉中,外侧型8例,内侧型1例;按Saltzman分型Ⅰ型3例,Ⅱ型2例,Ⅲ型4例;吻合点近端的基底动脉及双侧椎动脉发育不良4例,吻合点近端基底动脉完全萎缩1例;1例合并动脉瘤,2例合并大脑中动脉成窗。3例永存舌下动脉中,2例伴同侧椎动脉缺如,1例伴对侧椎动脉发育不良,1例伴对侧椎动脉发育不良及成窗变异。结论(1)CTA及MRA能清晰、快速、准确地显示永存三叉动脉和永存舌下动脉等颈内-基底动脉吻合的走行、毗邻关系及其合并症;(2)熟悉这些原始吻合血管的特征有助于指导临床制定合理的治疗方案,提高相应治疗中的安全性。%Objective To explore the imaging characteristics of persistent carotid-basilar artery anastomoses in an effort to improve our understanding of this anomaly. Methods 9 craniocervical CT angiography(CT A), 3 cranial and/or cervical MR angiography (MRA) in 12 patients of persistent carotid-basilar artery anastomoses were retrospectively reviewed. Results These 12 patients had 9 persistent trigeminal arteries and 3 persistent hypoglossal arteries. Based on the position of the persistent trigeminal artery, 8 patients were the lateral type, 1 was the medial type. According to the configuration of the ipsilateral posterior cerebral artery, 3 cases were Saltzman type I persistent trigeminal arteries,2 cases were Saltzman type II ,4 were Saltzman type Ⅲ . The veretral artery and basilar artery caudal to the anastomosis with the trigeminal artery were

  18. Electrophysiology of mycoplasma membranes.

    OpenAIRE

    Schummer, U.; Schiefer, H G

    1983-01-01

    The influence of transmembrane ion fluxes on mycoplasma membrane potentials was studied. Fluorescence intensity of potential-sensitive carbocyanine dyes was calibrated vs. electric membrane potential. Potassium and sodium ion diffusion potentials significantly contributed to mycoplasma membrane potential. Chloride ions were obviously freely permeable across mycoplasma membranes. Under growth conditions the mycoplasma membrane potential was estimated to be delta psi = - 80 mV.

  19. 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

  20. Clinical characteristics and treatment for vertebral basilar artery dissection%椎-基底动脉夹层的临床特点和治疗

    Institute of Scientific and Technical Information of China (English)

    郑峥; 程琼; 李永坤; 刘君鹏; 陈莹; 汪银洲

    2012-01-01

    Objective To investigate the clinical characteristics, therapeutic strategies and efficacy of vertebral basilar artery dissection (VAD). Methods Twenty-eight patients with VAD diagnosed by DSA or CTA were collected. 21 of the patients wilh posterior circulation ischemia (PCI) were treated with clopidogrel (75 mg/d) or aspirin (100 mg/d) alone, 3 underwent endovascular treatment, and 2 with sub-arachnoid hemorrhage (SAH) were treated with stent-assisted coil embolization of the aneurysms and vertebral artery occlusion. The clinical characteristics and follow-up results were analyzed. Results ①In the 28 patients, 24 had clear causes or incentive factors, including abnormal movement of the head and neck (15/24, 53.6% ), atherosclerosis (4/24, 16.7%), upper respiratory tract infection (12.5% , 3/24), thrombocytosis (4. 2% , 1/24), and alcoholism (4.2% , 1/24); 4 were cryptogenic. ② In the 28 patients, 25 (89.3% ) had PCI (21 of them had posterior circulation infarct, 4 had repeated transient episodes of vertigo), and 3 patients( 10.7% ) had SAH. ③DSA or CTA showed that 30 vertebral arteries and 1 basilar artery had dissection, 16 (51.6%) showed "linear sign", 9 (29.0%) showed fusiform or saccular aneurysm6, 6(19.4%) showed "pearl and string sign", and 2(6.5%) had double-lumen sign. Most dissections were oc-cured in the V4 segments (71.0% ,up to 22/31), then Mowed by V2 segments (19.4% , 6/31). ④In the 25 patients with PCI, 21 were treated with medication, 19 had good and 2 had poor prognosis. 9 patients received CTA or DSA reexamination, the degree of vascular stenosis reduced in 4 patients, no significant change in 4 patients, and 1 patient's vertebral artery was occluded. Three patients treated with endovascular treatment, and their prognosis was good. CTA reexamination no vascular restenosis or aneurysm recurrence was found. Two of the 3 patients with SAH had good prognosis. CTA reexamination showed no recurrence of aneurysms; 1 patient was only treated with

  1. 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.

  2. Anaerobic membrane bioreactors: Are membranes really necessary?

    OpenAIRE

    Davila, M.; Kassab, G.; Klapwijk, A.; Van, Lier, G

    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 self-forming dynamic membrane only requires a support material over which a cake layer is formed, which determines the rejection properties of the system. The present research studies the applicat...

  3. 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

  4. 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.

  5. 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

  6. 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.

  7. 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

  8. A membrane disdrometer based on membrane vibration

    International Nuclear Information System (INIS)

    Raindrop sizes were indirectly determined through the distinctive vibrations and sounds that occur when raindrops of different sizes impact on a membrane. The relationships between diameter, raindrop kinetic momentum, membrane deflection, and impact force were analyzed. Membrane deflection and vibration models were created, and the optimum membrane diameter and thickness were identified. A prototype membrane disdrometer was developed on the basis of these findings. The relationship between raindrop size and membrane vibration sound pressure was determined experimentally. The fundamental parameter of raindrop size recognition was used. The test results indicate that raindrops 0.4–2.0 mm in diameter can be detected by the proposed membrane disdrometer, and 50 raindrops per second in a zone area of 28.3 cm2 can be detected in natural rain. (paper)

  9. 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.

  10. 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.

  11. 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.

  12. 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

  13. Membrane fluids and Dirac membrane fluids

    CERN Document Server

    Ivanov, M G

    2004-01-01

    The relation between two different methods of membrane fluid description is clarified by construction of combined method. Dirac membrane field appears naturally in new approach. It provides a possibility to consider new aspects of electrodynamics-type theories with electric and magnetic sources. The membrane fluid models automatically prohibit simulatenos existence of electric and magnetic currents. Possible applications to the dark energy problem are mentioned.

  14. 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.

  15. 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.

  16. 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....

  17. Solvent resistant nanofiltration membranes

    OpenAIRE

    Dutczak, Szymon Maria

    2011-01-01

    This thesis describes preparation and characterization of membranes for organic solvent filtration (OSF). The main aim was developing membranes for solvent resistant nanofiltration (SRNF) with molecular weight cut-off below 500 g mol-1.

  18. 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.

  19. 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.

  20. Membrane Curvature in Flaviviruses

    OpenAIRE

    Zhang, Wei; Kaufmann, Bärbel; Chipman, Paul R.; Kuhn, Richard J; Rossmann, Michael G.

    2013-01-01

    Coordinated interplay between membrane proteins and the lipid bilayer is required for such processes as transporter function and the entrance of enveloped viruses into host cells. In this study, three-dimensional cryo-electron microscopy density maps of mature and immature flaviviruses were analyzed to assess the curvature of the membrane leaflets and its relation to membrane-bound viral glycoproteins. The overall morphology of the viral membrane is determined by icosahedral scaffolding compo...

  1. 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...

  2. 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

  3. 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.

  4. 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...... membrane include ABC transporters, vacuolar (V-type) H+ pumps, and P-type pumps. These pumps all utilize ATP as a fuel for energizing pumping. This review focuses on the physiological roles of plasma membrane P-type pumps, as they represent the major ATP hydrolytic activity in this membrane....

  5. 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.

  6. Elastic membranes in confinement

    Science.gov (United States)

    Bostwick, Joshua; Miksis, Michael; Davis, Stephen

    2014-11-01

    An elastic membrane stretched between two walls takes a shape defined by its length and the volume of fluid it encloses. Many biological structures, such as cells, mitochondria and DNA, have finer internal structure in which a membrane (or elastic member) is geometrically ``confined'' by another object. We study the shape stability of elastic membranes in a ``confining'' box and introduce repulsive van der Waals forces to prevent the membrane from intersecting the wall. We aim to define the parameter space associated with mitochondria-like deformations. We compare the confined to `unconfined' solutions and show how the structure and stability of the membrane shapes changes with the system parameters.

  7. 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.

  8. Microporous silica membranes

    DEFF Research Database (Denmark)

    Boffa, Vittorio; Yue, Yuanzheng

    2012-01-01

    Hydrothermal stability is a crucial factor for the application of microporous silica-based membranes in industrial processes. Indeed, it is well established that steam exposure may cause densification and defect formation in microporous silica membranes, which are detrimental to both membrane...... permeability and selectivity. Numerous previous studies show that microporous transition metal doped-silica membranes are hydrothermally more stable than pure silica membranes, but less permeable. Here we present a quantitative study on the impact of type and concentration of transition metal ions on the...... microporous structure, stability and permeability of amorphous silica-based membranes, providing information on how to design chemical compositions and synthetic paths for the fabrication of silica-based membranes with a well accessible and highly stabile microporous structure....

  9. 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。

  10. 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.

  11. 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.

  12. 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.

  13. 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.

  14. 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.

  15. Drugging Membrane Protein Interactions.

    Science.gov (United States)

    Yin, Hang; Flynn, Aaron D

    2016-07-11

    The majority of therapeutics target membrane proteins, accessible on the surface of cells, to alter cellular signaling. Cells use membrane proteins to transduce signals into cells, transport ions and molecules, bind cells to a surface or substrate, and catalyze reactions. Newly devised technologies allow us to drug conventionally "undruggable" regions of membrane proteins, enabling modulation of protein-protein, protein-lipid, and protein-nucleic acid interactions. In this review, we survey the state of the art of high-throughput screening and rational design in drug discovery, and we evaluate the advances in biological understanding and technological capacity that will drive pharmacotherapy forward against unorthodox membrane protein targets. PMID:26863923

  16. 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.

  17. 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

  18. Stability of charged membranes

    OpenAIRE

    Bensimon, D; David, F.; Leibler, S.; Pumir, A.

    1990-01-01

    The electrostatic contribution to the bending elastic modulus of charged phospholipid bilayers in an ionic solution is computed. It is found to be the same for conducting and non-conducting membranes and is always stabilizing. This stability for free membranes is shown to be a simple consequence of the vanishing of the physical surface tension.

  19. Membrane projection lithography

    Science.gov (United States)

    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.

  20. 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.

  1. Development of hybride membrane materials (mixed matrix membranes)

    OpenAIRE

    Borge, Tone

    2010-01-01

    The existence of an upper bound for the separation performance of polymeric membranes has motivated the development of new membrane materials with improved separation performance. Inorganic porous membranes like carbon molecular sieve (CMS) or zeolites have superior separation performance compared to polymeric membranes, but a challenging and costly manufacturing process have limited the commercialization of these membranes so far. Mixed matrix membranes (MMMs) consisting of porous inorganic ...

  2. 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.

  3. 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. PMID:23735989

  4. 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

  5. Membrane photobiophysics and photochemistry

    Science.gov (United States)

    Ti Tien, H.

    Life, as we know it, depends on solar energy, in particular in the visible range of the solar spectrum. However, visible light alone is useless to the living organism unless a means is available for its capture, transformation, and utilization. Nature, through its long evolution, has perfected a process known as photosynthesis by which visible light is transduced into electrical/ chemical energy. However, the heart of Nature's energy transducer is the thylakoid membrane whose molecular organization was not known until early in the 1960s. Then it was established that the bilayer lipid membrane was central to the design of the thylakoid membrane. To explain the light-driven reactions from water oxidation to carbon dioxide reduction, the so-called Z-scheme was proposed. Concurrent with the establishment of Mitchell's Chemiosmotic Hypothesis for electron transfer and phosphorylation, the experimental bilayer lipid membrane (BLM) system was developed in 1960. But what are the fundamental biophysical mechanisms involved in the phototransduction via pigmented bilayer lipid membrane-based transducers? One of the main purposes of this review is to consider these questions. A second main purpose is to introduce to the reader the experimental aspects of lipid bilayers in the investigation of photoactive biomembranes. The areas covered in this review include a brief summary of the laws of photochemistry relevant to membrane photobiophysics and photobiology. The current exploitation of the BLM system in relation to the thylakoid membrane and to the visual receptor membrane will be considered in turn. The purple membrane of H. Halobium is then discussed. Consideration will also be given to dye-sensitized BLMs, semiconducting BLMs, and BLMs formed from liquid crystals. A common characteristic in the topics covered in this review is the desire to stimulate further studies in the use of the BLM system, not only for the fundamental understanding of biomembranes, but also towards

  6. 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.

  7. 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.

  8. Clinical course of a partially thrombosed, symptomatic aneurysm of the basilar artery tip with partial recanalization subsequent to coiling; Verlaufsbeschreibung eines teilthrombosierten symptomatischen Basilariskopfaneurysmas mit teilweiser Rekanalisierung nach Coiling

    Energy Technology Data Exchange (ETDEWEB)

    Moeller, V. [Universitaet des Saarlandes, Abteilung fuer Neuroradiologie, Homburg (Germany); Klinikum Saarbruecken, Institut fuer bildgebende Diagnostik und Interventionen, Saarbruecken (Germany); Axmann, C.; Reith, W. [Universitaet des Saarlandes, Abteilung fuer Neuroradiologie, Homburg (Germany)

    2006-05-15

    A 72-year-old patient was referred to the neuroradiological department for diagnostic angiography. She was suffering from vertigo and double vision. Magnetic resonance imaging performed elsewhere had demonstrated a giant aneurysm of the basilar artery tip 2 cm in diameter. Angiography revealed a large aneurysm with a broad neck that was partially thrombosed, which precluded closure by coiling. Neurosurgical management by clipping also appeared to be unsuitable because of the proximity to the cerebrum. The decision was reached to proceed expectantly by closely monitoring the clinical course. When the aneurysm increased in size in the ensuing weeks, coiling was performed successfully. Angiographic follow-up showed reperfusion of the aneurysm neck and closure was again achieved by repeat coiling. Reperfusion is not a rare complication following coiling and often necessitates renewed intervention. (orig.) [German] Eine 72-jaehrige Patientin wurde in der neuroradiologischen Abteilung zur diagnostischen Angiographie vorgestellt. Sie litt unter Schwindel und Doppelbildern. Eine auswaertige MR-Untersuchung des Gehirns zeigte ein Riesenaneurysma des Basilariskopfes mit einem Durchmesser von 2 cm. Die Angiographie zeigte ein grosses Aneurysma mit breitem Hals, das teilweise thrombosiert war. Dies liess einen Verschluss durch Coiling nicht zu. Eine neurochirurgische Behandlung durch Klippung erschien wegen der Naehe zum Mittelhirn ebenfalls ungeeignet. Man einigte sich auf ein abwartendes Vorgehen durch eine engmaschige Verlaufsbeobachtung. Als das Aneurysma in den folgenden Wochen eine Groessenzunahme zeigte, wurde erfolgreich ein Coiling durchgefuehrt. Eine angiographische Verlaufskontrolle zeigte eine Reperfusion des Aneurysmahalses. Erneut konnte ein Verschluss durch Coiling erzielt werden. Eine Reperfusion ist keine seltene Komplikation nach Coiling, die oft eine erneute Intervention erfordert. (orig.)

  9. Treatment of symptomatic basilar artery atheronatous ischemic disease with Wingspan stent system%症状性基底动脉粥样硬化性狭窄Wingspan支架成形术的临床研究

    Institute of Scientific and Technical Information of China (English)

    王子亮; 蔡栋阳; 许斌; 李天晓

    2015-01-01

    Objective To explore the safety and efficacy of the Wingspan stenting of basilar artery atherosclerosis stenosis though the analysis of single center massive clinical data. Methods Ninety one consecutive patients received Wingspan stenting because of basilar artery stenosis in our center from July 2007 to April 2013. The patients were classified into three groups:early term (n=30), middle term (n=30), and late term (n=31) according to the operation time in our center. The basic clinical data and the factors which may affect the ischemic events were retrospectively analysed, t test and Chi⁃Square test were used to analyze the factors related to the periprocedural ischemic complications. Results All of patients were stented successfully and the technical success rate was 100%(91/91). The mean stenosis was reduced from (82.2 ± 5.8)% to (15.9 ± 5.7)%; strokes or death happened in 13 cases within 30 days, including perforator stroke in 8 patients(8.8%, 8/91), thrombosis in 4 patients(4.4%, 4/91), subarachnoid hemo rrhage in 1 patient(1.1%, 1/91), 2 patients with disabling or fatal strokes. Lesions involving in the middle segment of basal artery (P=0.049), long⁃segment disease (P=0.002), severe stenosis (P=0.001) may be a risk factor affecting perioperative ischemic stroke, and the surgeons' surgical technique was not risk factors for ischemic complications (P=1.000). Seventy seven patients (84.6%, 77/91) had the clinical follow⁃up and the mean follow⁃up period was (31.3±15.1) months. Four patients suffered from posterior circulation strokes during the clinical follow⁃up , one of them (1.3%, 1/77) had disabling stroke, another 3 patients (3.9%, 3/77) suffered from TIA. The 2⁃year accumulate probability of stroke (any stroke or death within 30 days and stroke in the territory of the qualifying artery beyond 30 days)was 16%(95%CI, 8.2%to 23.8%). Forty six patients had the imaging follow⁃up and the mean follow⁃up period was(9.5±8.3)months, 6 patients(13

  10. Rotating bubble membrane radiator

    Science.gov (United States)

    Webb, Brent J.; Coomes, Edmund P.

    1988-12-06

    A heat radiator useful for expelling waste heat from a power generating system aboard a space vehicle is disclosed. Liquid to be cooled is passed to the interior of a rotating bubble membrane radiator, where it is sprayed into the interior of the bubble. Liquid impacting upon the interior surface of the bubble is cooled and the heat radiated from the outer surface of the membrane. Cooled liquid is collected by the action of centrifical force about the equator of the rotating membrane and returned to the power system. Details regarding a complete space power system employing the radiator are given.

  11. 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.

  12. 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...

  13. 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

  14. 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.

  15. 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.

  16. 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.

  17. 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. PMID:27318159

  18. Lipid Membranes in Poxvirus Replication

    Directory of Open Access Journals (Sweden)

    Jason P. Laliberte

    2010-04-01

    Full Text Available Poxviruses replicate in the cytoplasm, where they acquire multiple lipoprotein membranes. Although a proposal that the initial membrane arises de novo has not been substantiated, there is no accepted explanation for its formation from cellular membranes. A subsequent membrane-wrapping step involving modified trans-Golgi or endosomal cisternae results in a particle with three membranes. These wrapped virions traverse the cytoplasm on microtubules; the outermost membrane is lost during exocytosis, the middle one is lost just prior to cell entry, and the remaining membrane fuses with the cell to allow the virus core to enter the cytoplasm and initiate a new infection.

  19. 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...

  20. 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.

  1. 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

  2. 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.

  3. M, Membranes, and OM

    International Nuclear Information System (INIS)

    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 this setting. For two of these types, the action in question can be simplified by gauge-fixing to a form which implies a discrete membrane spectrum. The boundary conditions for the remaining two cases do not allow this same gauge choice, and so their dynamics remain to be unraveled

  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. 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

  7. Supported microporous ceramic membranes

    Science.gov (United States)

    Webster, E.; Anderson, M.

    1993-12-14

    A method for the formation of microporous ceramic membranes onto a porous support includes placing a colloidal suspension of metal or metal oxide particles on one side of the porous support and exposing the other side of the porous support to a drying stream of gas or a reactive gas stream so that the particles are deposited on the drying side of the support as a gel. The gel so deposited can be sintered to form a supported ceramic membrane useful for ultrafiltration, reverse osmosis, or molecular sieving having mean pore sizes less than 100 Angstroms. 4 figures.

  8. Effective rigidity of membranes

    Science.gov (United States)

    Peliti, L.

    1986-12-01

    The role of thermal fluctuations of shape (undulations) in reducing the effective rigidity of membranes is reviewed. The consequences of this effect on vesicle size distribution and on the structure of microemulsions, as well as on other physical phenomena, are sketched.

  9. 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...

  10. Imaging of membranous dysmenorrhea

    International Nuclear Information System (INIS)

    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.)

  11. 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.)

  12. 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.

  13. 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 ...

  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. 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.

  16. 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

  17. Process of treating cellulosic membrane and alkaline with membrane separator

    Science.gov (United States)

    Hoyt, H. E.; Pfluger, H. L. (Inventor)

    1970-01-01

    The improvement of water-soluble cellulose ether membranes for use as separators in concentrated alkaline battery cells is discussed. The process of contacting membranes with an aqueous alkali solution of concentration less than that of the alkali solution to be used in the battery but above that at which the membrane is soluble is described.

  18. 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

  19. 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.

  20. 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

  1. Lipid membranes with an edge

    OpenAIRE

    Capovilla, R.; Guven, J.; Santiago, J. A.

    2002-01-01

    Consider a lipid membrane with a free exposed edge. The energy describing this membrane is quadratic in the extrinsic curvature of its geometry; that describing the edge is proportional to its length. In this note we determine the boundary conditions satisfied by the equilibria of the membrane on this edge, exploiting variational principles. The derivation is free of any assumptions on the symmetry of the membrane geometry. With respect to earlier work for axially symmetric configurations, we...

  2. Fuel cell with ionization membrane

    Science.gov (United States)

    Hartley, Frank T. (Inventor)

    2007-01-01

    A fuel cell is disclosed comprising an ionization membrane having at least one area through which gas is passed, and which ionizes the gas passing therethrough, and a cathode for receiving the ions generated by the ionization membrane. The ionization membrane may include one or more openings in the membrane with electrodes that are located closer than a mean free path of molecules within the gas to be ionized. Methods of manufacture are also provided.

  3. Neurofibromatosis, stroke and basilar impression: case report

    OpenAIRE

    PIOVESAN ELCIO JULIATO; SCOLA ROSANA HERMINIA; WERNECK LINEU CESAR; ZÉTOLA VIVIANE H. FLUMIGNAN; NÓVAK EDISON MATOS; IWAMOTO FABIO MASSAITI; PIOVESAN LICIANE MAIA

    1999-01-01

    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...

  4. 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.

  5. 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...

  6. Bioenergetics: Proton fronts on membranes

    Science.gov (United States)

    Agmon, Noam; Gutman, Menachem

    2011-11-01

    Proton migration on membranes is a crucial step in the bioenergetics of the cell. It has typically been regarded as slow successive proton transfers between ionizable moieties within the membrane, but recent measurements suggest fast lateral diffusion in the membrane's hydration layer.

  7. 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

  8. Membrane tension and peripheral protein density mediate membrane shape transitions

    Science.gov (United States)

    Shi, Zheng; Baumgart, Tobias

    2015-01-01

    Endocytosis is a ubiquitous eukaryotic membrane budding, vesiculation and internalization process fulfilling numerous roles including compensation of membrane area increase after bursts of exocytosis. The mechanism of the coupling between these two processes to enable homeostasis is not well understood. Recently, an ultrafast endocytosis (UFE) pathway was revealed with a speed significantly exceeding classical clathrin-mediated endocytosis (CME). Membrane tension reduction is a potential mechanism by which endocytosis can be rapidly activated at remote sites. Here, we provide experimental evidence for a mechanism whereby membrane tension reduction initiates membrane budding and tubulation mediated by endocytic proteins, such as endophilin A1. We find that shape instabilities occur at well-defined membrane tensions and surface densities of endophilin. From our data, we obtain a membrane shape stability diagram that shows remarkable consistency with a quantitative model. This model applies to all laterally diffusive curvature-coupling proteins and therefore a wide range of endocytic proteins.

  9. Membrane accessibility of glutathione

    DEFF Research Database (Denmark)

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

    2015-01-01

    Regulation of the ion pumping activity of the Na(+),K(+)-ATPase is crucial to the survival of animal cells. Recent evidence has suggested that the activity of the enzyme could be controlled by glutathionylation of cysteine residue 45 of the β-subunit. Crystal structures so far available indicate...... 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 was found. Therefore, the most likely mechanism whereby the cysteine residue could become glutathionylated is via a loosening of the α-β subunit association, creating a hydrophilic passageway between them to allow access of glutathione to the cysteine residue. By such a mechanism...

  10. 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...

  11. 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.

  12. Pulse radiolysis studies of model membranes

    International Nuclear Information System (INIS)

    In this thesis the influence of the structure of membranes on the processes in cell membranes were examined. Different models of the membranes were evaluated. Pulse radiolysis was used as the technique to examine the membranes. (R.B.)

  13. 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

  14. 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...... liposomes. The lipid-induced changes in the peptide due to membrane binding, and the peptide-induced changes in the membrane properties were investigated using various spectroscopic and calorimetric methods, and the structural and thermodynamic aspects of peptide-lipid interactions are discussed. This helps...... in understanding not only the antimicrobial nature of Novicidin, but also sheds light on the membrane-peptide interactions....

  15. 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.

  16. 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).

  17. 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.

  18. 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.

  19. 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.

  20. Viral membrane fusion

    International Nuclear Information System (INIS)

    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

  1. 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.

  2. 闭孔神经与膀胱肿瘤基底部联合阻滞在经尿道膀胱肿瘤电切术中的应用%The Application of Combined Blockade of Obturator Nerve and Basilar Part of Bladder Tumor in Transurethral Electroresection of Bladder Tumor

    Institute of Scientific and Technical Information of China (English)

    李颖波; 余开峰; 冉然

    2012-01-01

    Objective To investigate the combined blockade of the feasibility of obturator nerve and basilar part of bladder tumor in preventing obturator nervous reflex during transurethral electroresection of bladder tumor (TURBT). Methods Seventy - two patients with bladder tumor close to the ureter,suffered from TURBT under combined spinal epidural anesthesia, were randomly divided into two group: N group ( n = 36) and P group (n = 36). Before TURBT, obturator nerve blockade under guidance of nerve stimulator were performed in N group. Obturator nerve and basilar part of bladder tumor combined blockade were performed in P group. Results In N group,seven patients (7/36, 19% ) showed obturator nervous reflex during TURBT, five patients showed slight obturator nervous reflex, two patients showed apparent nervous reflex. In P group,only three patients (3/36,8% ) showed slight obturator nervous reflex during TURBT without vesical perforation. Compared with N group, there had a significant difference (P<0.05). Conclusion In TURBT,the combined blockade of obturator nerve and basilar part of bladder tumor could inhibit the obturator nerve reflex and decrease the incidence of operative complications.%目的:探讨闭孔神经与膀胱肿瘤基底部联合阻滞在经尿道膀胱肿瘤电切术(TURBT)中预防闭孔神经反射的可行性.方法:72例膀胱肿瘤位于输尿管附近拟行经尿道膀胱肿瘤电切术患者,均在腰-硬联合麻醉下行TURBT,单阻滞组在神经刺激器指导下行闭孔神经阻滞,联合阻滞组行闭孔神经与膀胱肿瘤基底部联合阻滞,再行膀胱肿瘤电切.结果:单阻滞组有7例(19%)出现闭孔神经反射,5例轻微,2例严重;联合阻滞组仅有3例(8%)出现轻微的闭孔神经反射,无膀胱穿孔(P<0.05).结论:经尿道膀胱肿瘤电切术闭孔神经与膀胱肿瘤基底部联合阻滞能有效抑制闭孔神经反射,减少手术并发症.

  3. 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......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 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....

  4. 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.

  5. 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.

  6. 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

  7. 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

  8. Flux Enhancement in Membrane Distillation Using Nanofiber Membranes

    Directory of Open Access Journals (Sweden)

    T. Jiříček

    2016-01-01

    Full Text Available Membrane distillation (MD is an emerging separation technology, whose largest application potential lies in the desalination of highly concentrated solutions, which are out of the scope of reverse osmosis. Despite many attractive features, this technology is still awaiting large industrial application. The main reason is the lack of commercially available membranes with fluxes comparable to reverse osmosis. MD is a thermal separation process driven by a partial vapour pressure difference. Flux, distillate purity, and thermal efficiency are always in conflict, all three being strictly connected with pore size, membrane hydrophobicity, and thickness. The world has not seen the ideal membrane yet, but nanofibers may offer a solution to these contradictory requirements. Membranes of electrospun PVDF were tested under various conditions on a direct contact (DCMD unit, in order to determine the optimum conditions for maximum flux. In addition, their performance was compared to commonly available PTFE, PE, and PES membranes. It was confirmed that thinner membranes have higher fluxes and a lower distillate purity and also higher energy losses via conduction across the membrane. As both mass and heat transfer are connected, it is best to develop new membranes with a target application in mind, for the specific membrane module and operational conditions.

  9. Inducing effect of total flavones in rhododendra on endothelium-derived hyperpolarizing factor responses in cerebral basilar artery of rats subjected to global cerebral ischemia reperfusion%映山红花总黄酮对全脑缺血再灌注大鼠脑基底动脉超极化反应的诱导作用

    Institute of Scientific and Technical Information of China (English)

    韩黎黎; 范一菲; 陈志武

    2011-01-01

    Objective To study the effect of endothelium-derived hyperpolarizing factor (EDHF)-mediated responses of relaxation and hyperpolarization of vascular smooth muscle cell (VSMC) of rat cerebral basilar artery (CBA) subjected to cerebral ischemia/reperfusion (I/R) to total flavones in rhododendra (TFR). Methods The model of global cerebral I/R in rats was made by 4-vessel occlusion (4-VO). The vasodilation and resting membrane potential (RMP) of VSMC of rat CBA were detected in vitro.Results In the presence of 3×10-5 mol/L Nω-nitro-L-arginine-methyl-ester (L-NAME, an inhibitor of nitric oxide synthase) and 1 × 10-5 mol/L Indomethacin (Indo, an inhibitor of PGI2 synthesis), the global cerebral I/R markedly enhanced 1 × 10-7-1 × 10-5 mol/L acetylcholine (Ach)-elicited relaxation and hyperpolarization of RMP of VSMC in rat CBA. In the presence of L-NAME and Indo, 11 -2 700 mg/L TFR induced significant and dose-dependent hyperpolarization of RMP of VSMC and relaxation of rat CBA subjected to global cerebral I/R. The hyperpolarization and relaxation were obviously inhibited by tetraethylammonium (an inhibitor of IKca at 1 mmol/L) and 1 ×10-4 mol/L dl-propargylglycine (PPG), an inhibitor of endogenous hydrogen sulfide (H2S) synthase. Conclusion Global cerebral I/R could enhance the non-NO-non-PGI2-mediated responses of hyperpolarization and vasorelaxation in rat CAB. In rat CAB subjected to global cerebral I/R, TFR could significantly induce this non-NO-non-PGl2 hyperpolarization and relaxation, the so-called EDHF response that might be mediated by endogenous H2S.%目的 探讨映山红花总黄酮(TFR)对内皮源性超极化因子(EDHF)介导的全脑缺血再灌注大鼠脑基底动脉(CBA)血管舒张和平滑肌细胞膜静息电位超极化反应的诱导作用.方法 采用四血管结扎法建立大鼠全脑缺血再灌注模型,测定离体大鼠CBA平滑肌细胞膜静息电位和血管舒张功能.结果 在3×10-5mol/L L-NAME和1×10-5mol/L吲哚美辛存

  10. 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.

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

    International Nuclear Information System (INIS)

    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

  12. 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.

  13. Molecular simulation of realistic membrane models of alkylated PEEK membranes

    OpenAIRE

    Tocci, Elena; Pullumbi, Pluton

    2006-01-01

    Abstract Atomistic molecular modelling has proven to be a useful tool for the investigation of transport properties of small gas molecules in polymer membrane matrices. The quality of the predictions of these properties based on molecular simulation depends principally on the quality of the membrane model. The predicted gas transport properties of small gas molecules in the same glassy polymer membrane show often a large scatter in gas diffusion and solubility simulated values. In ...

  14. STUDYING MEMBRANE ANCHOR ORGANIZATION IN LIVING CELL MEMBRANES

    OpenAIRE

    Huang, Hector Han-Li

    2011-01-01

    The cell membrane is a complex mixture of various lipids, proteins and other biomolecules that are all organized into a fluid 2-dimensional bilayer. A rather unique trait of this organelle is the lateral mobility of the component molecules. Surprisingly, these molecules are not necessarily distributed homogeneously in the membrane. From a physical perspective, these inhomogeneities are interesting because they indicate some level of organization in the membrane. From a biological perspect...

  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. 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.

  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. 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.

  19. 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

  20. Proteins interacting with Membranes: Protein Sorting and Membrane Shaping

    Science.gov (United States)

    Callan-Jones, Andrew

    2015-03-01

    Membrane-bound transport in cells requires generating membrane curvature. In addition, transport is selective, in order to establish spatial gradients of membrane components in the cell. The mechanisms underlying cell membrane shaping by proteins and the influence of curvature on membrane composition are active areas of study in cell biophysics. In vitro approaches using Giant Unilamellar Vesicles (GUVs) are a useful tool to identify the physical mechanisms that drive sorting of membrane components and membrane shape change by proteins. I will present recent work on the curvature sensing and generation of IRSp53, a protein belonging to the BAR family, whose members, sharing a banana-shaped backbone, are involved in endocytosis. Pulling membrane tubes with 10-100 nm radii from GUVs containing encapsulated IRSp53 have, unexpectedly, revealed a non-monotonic dependence of the protein concentration on the tube as a function of curvature. Experiments also show that bound proteins alter the tube mechanics and that protein phase separation along the tube occurs at low tensions. I will present accompanying theoretical work that can explain these findings based on the competition between the protein's intrinsic curvature and the effective rigidity of a membrane-protein patch.

  1. Spherical membranes in Matrix theory

    CERN Document Server

    Kabat, D; Kabat, Daniel; Taylor, Washington

    1998-01-01

    We consider membranes of spherical topology in uncompactified Matrix theory. In general for large membranes Matrix theory reproduces the classical membrane dynamics up to 1/N corrections; for certain simple membrane configurations, the equations of motion agree exactly at finite N. We derive a general formula for the one-loop Matrix potential between two finite-sized objects at large separations. Applied to a graviton interacting with a round spherical membrane, we show that the Matrix potential agrees with the naive supergravity potential for large N, but differs at subleading orders in N. The result is quite general: we prove a pair of theorems showing that for large N, after removing the effects of gravitational radiation, the one-loop potential between classical Matrix configurations agrees with the long-distance potential expected from supergravity. As a spherical membrane shrinks, it eventually becomes a black hole. This provides a natural framework to study Schwarzschild black holes in Matrix theory.

  2. 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.

  3. When plasmonics meets membrane technology

    Science.gov (United States)

    Politano, A.; Cupolillo, A.; Di Profio, G.; Arafat, H. A.; Chiarello, G.; Curcio, E.

    2016-09-01

    In this review, we present the applications of thermoplasmonics in membrane processes. We discuss the influence of the heat capacity of the solvent, the amount of plasmonic nanoparticles in the membrane, the intensity of the light source and the transmembrane flow rate on the increase of permeability. Remarkably, thermoplasmonic effects do not involve any noticeable loss of membrane rejection. Herein, we consider application feasibilities, including application fields, requirements of feed, alternatives of light sources, promising thermoplasmonic nanoparticles and scaling up issues.

  4. When plasmonics meets membrane technology.

    Science.gov (United States)

    Politano, A; Cupolillo, A; Di Profio, G; Arafat, H A; Chiarello, G; Curcio, E

    2016-09-14

    In this review, we present the applications of thermoplasmonics in membrane processes. We discuss the influence of the heat capacity of the solvent, the amount of plasmonic nanoparticles in the membrane, the intensity of the light source and the transmembrane flow rate on the increase of permeability. Remarkably, thermoplasmonic effects do not involve any noticeable loss of membrane rejection. Herein, we consider application feasibilities, including application fields, requirements of feed, alternatives of light sources, promising thermoplasmonic nanoparticles and scaling up issues. PMID:27414212

  5. Hydrophobic organization of membrane proteins

    OpenAIRE

    Rees, D C; DeAntonio, L.; Eisenberg, D.

    1989-01-01

    Membrane-exposed residues are more hydrophobic than buried interior residues in the transmembrane regions of the photosynthetic reaction center from Rhodobacter sphaeroides. This hydrophobic organization is opposite to that of water-soluble proteins. The relative polarities of interior and surface residues of membrane and water soluble proteins are not simply reversed, however. The hydrophobicities of interior residues of both membrane and water-soluble proteins are comparable, whereas the bi...

  6. A Molecular Look at Membranes.

    Science.gov (United States)

    Berkowitz, Max

    2016-01-01

    Due to the recent advances in computer hardware and software, we can now use molecular dynamics and Monte Carlo computer simulation techniques to study systems with large conformational spaces. It is demonstrated here that computer simulations allow us to get a glimpse at the structural and dynamical properties of membranes and also at the interaction of membranes with other molecules. Specifically two examples are considered: (1) structural properties of lipid rafts in model membranes and (2) interaction of model membranes with an antimicrobial peptide, melittin. PMID:26781828

  7. 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

  8. 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...... affected by the lipid environment. Theoretical predictions are pointed out, and compared to experimental findings, if available. Among others, the following phenomena are discussed: interactions of interfacially adsorbed peptides, pore-forming amphipathic peptides, adsorption of charged proteins onto...... oppositely charged lipid membranes, lipid-induced tilting of proteins embedded in lipid bilayers, protein-induced bilayer deformations, protein insertion and assembly, and lipid-controlled functioning of membrane proteins....

  9. Physical Properties of Biological Membranes

    CERN Document Server

    Heimburg, Thomas

    2009-01-01

    Biological membranes mainly consist of lipids and proteins. While the proteins have many functions as single molecules, the membrane as a whole displays physical properties that cannot be explained on the single molecule level. For example, membranes show melting events, phase behavior, and elasticity. Biomembranes adapt their composition such that the physical properties are maintained when the external conditions change. This gives a role to changes in composition, to temperature and pressure. This article introduces into the physics of membranes as a whole and shows how phenomena as permeability, pulse propagation and the effect of anesthetics arise.

  10. 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.

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

    DEFF Research Database (Denmark)

    Bendix, Pól Martin

    2015-01-01

    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...

  12. 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

  13. 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

  14. 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.

  15. 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

  16. 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.

  17. 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

  18. Membrane duality revisited

    Science.gov (United States)

    Duff, M. J.; Lu, J. X.; Percacci, R.; Pope, C. N.; Samtleben, H.; Sezgin, E.

    2015-12-01

    Just as string T-duality originates from transforming field equations into Bianchi identities on the string worldsheet, so it has been suggested that M-theory U-dualities originate from transforming field equations into Bianchi identities on the membrane worldvolume. However, this encounters a problem unless the target space has dimension D = p + 1. We identify the problem to be the nonintegrability of the U-duality transformation assigned to the pull-back map. Just as a double geometry renders manifest the O (D , D) string T-duality, here we show in the case of the M2-brane in D = 3 that a generalized geometry renders manifest the SL (3) × SL (2) U-duality. In the case of M2-brane in D = 4, with and without extra target space coordinates, we show that only the GL (4 , R) ⋉R4 subgroup of the expected SL (5 , R) U-duality symmetry is realized.

  19. 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.

  20. Membranous lipodystrophy (Nasu)

    International Nuclear Information System (INIS)

    Three siblings with membranous lipodystrophy (Nasu) were reported. The parents were the first cousins. Case 1 (a 39 year old man), case 2 (a 33 year old man) and case 3 (a 30 year old female) all developed repeated pathological fractures of the long bone starting between the ages of 17 and 20. The neurological features were characterized by progressive dementia recognized at 24 years of age in case 1 and at approximately 30 years in cases 2 and 3. Plain roentgenograms of the long bones revealed multiple cystic lesions mostly in the epiphyses. Histological examination of the right tibia obtained by curettage in case 1 revealed a peculiar membranocystic structure. Serum levels of parathyroid hormone and calcitonin were normal. Ellsworth-Howard test showed a normal response. Skull x-ray films showed calcification of the basal ganglia in cases 1 and 3. Electroencephalograms showed generalized diffuse 3 - 6 Hz slow wave activities with temporo-occipital spikes in case 1, and frequent theta wave activities in case 2 and 3. CT scans were repeatedly performed in each case. The initial scan revealed calcification in the basal ganglia in all cases. Follow up CT scans in the next four years showed progressive brain atrophy in all cases including case 2 in which no atrophy was evident initially. It was concluded that intracranial calcification and progressive brain atrophy are frequent accompaniments of membranous lipodystrophy and can be readily detected on CT scans. It was also suggested that the degree of brain atrophy is closely related to that of dementia. (J.P.N.)

  1. 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

  2. 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

  3. 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 mathemat......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...... and the rejection coefficient. The second model is a stationary model for the flux of solvent and solute in a hollow fibre membrane. In the model we solve the time independent equations for transport of solvent and solute within the hollow fibre. Furthermore, the flux of solute and solvent through the membrane...

  4. Current-Induced Membrane Discharge

    DEFF Research Database (Denmark)

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

    2012-01-01

    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...

  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. 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.

  7. Hydrophobic compounds reshape membrane domains

    NARCIS (Netherlands)

    Barnoud, Jonathan; Rossi, Giulia; Marrink, Siewert J; Monticelli, Luca

    2014-01-01

    Cell membranes have a complex lateral organization featuring domains with distinct composition, also known as rafts, which play an essential role in cellular processes such as signal transduction and protein trafficking. In vivo, perturbations of membrane domains (e.g., by drugs or lipophilic compou

  8. Filtration characteristics in membrane bioreactors

    NARCIS (Netherlands)

    Evenblij, H.

    2006-01-01

    Causes of and remedies for membrane fouling in Membrane Bioreactors for wastewater treatment are only poorly understood and described in scientific literature. A Filtration Characterisation Installation and a measurement protocol were developed with the aim of a) unequivocally determination and quan

  9. 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.

  10. Staged membrane oxidation reactor system

    Science.gov (United States)

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

    2012-09-11

    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.

  11. 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

  12. Oligomerization of daptomycin on membranes.

    Science.gov (United States)

    Muraih, Jawad K; Pearson, Andre; Silverman, Jared; Palmer, Michael

    2011-04-01

    Daptomycin is a lipopeptide antibiotic that kills Gram-positive bacteria by membrane depolarization. While it has long been assumed that the mode of action of daptomycin involves the formation of membrane-associated oligomers, this has so far not been experimentally demonstrated. We here use FRET between native daptomycin and an NBD-labeled daptomycin derivative to show that such oligomerization indeed occurs. The oligomers are observed in the presence of calcium ions on membrane vesicles isolated from Bacillus subtilis, as well as on model membranes containing the negatively charged phospholipid phosphatidylglycerol. In contrast, oligomerization does not occur on membranes containing phosphatidylcholine only, nor in solution at micromolar daptomycin concentrations. The requirements for oligomerization of daptomycin resemble those previously reported for antibacterial activity, suggesting that oligomerization is necessary for the activity. PMID:21223947

  13. Reconstitution of Membrane Proteins into Model Membranes: Seeking Better Ways to Retain Protein Activities

    OpenAIRE

    Trevor Lithgow; Lisa Martin; Hsin-Hui Shen

    2013-01-01

    The function of any given biological membrane is determined largely by the specific set of integral membrane proteins embedded in it, and the peripheral membrane proteins attached to the membrane surface. The activity of these proteins, in turn, can be modulated by the phospholipid composition of the membrane. The reconstitution of membrane proteins into a model membrane allows investigation of individual features and activities of a given cell membrane component. However, the activity of mem...

  14. Centrifugal membrane filtration - Task 9

    International Nuclear Information System (INIS)

    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-microm TiO2/Al2O3 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

  15. 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.

  16. Gas separation with glass membranes

    Energy Technology Data Exchange (ETDEWEB)

    Roberts, D.L.; Abraham, L.C.; Blum, Y.; Way, J.D.

    1992-05-01

    The Department of Energy (DOE) is seeking to develop high temperature, high pressure inorganic membrane technology to perform a variety of gas separation processes to improve the efficiency and economics of advanced power generation systems such as direct coal-fueled turbines (DCFT) and the integrated gasification combined cycle process (IGCC). The temperatures encountered in these power generation systems are far above the temperature range for organic membrane materials. Inorganic materials such as ceramics are therefore the most likely membrane materials for use at high temperatures. This project focussed on silica glass fiber membranes made by PPG Industries (Pittsburgh, PA). The goals were both experimental and theoretical. The first objective was to develop a rational theory for the performance of these membranes. With existing theories as a starting point, a new theory was devised to explain the unusual molecular sieving'' behavior exhibited by these glass membranes. An apparatus was then devised for making permeation performance measurements at conditions of interest to DOE (temperatures to 2000[degrees]F; pressures to 1000 psia). With this apparatus, gas mixtures could be made typical of coal combustion or coal gasification processes, these gases could be passed into a membrane test cell, and the separation performance determined. Data were obtained for H[sub 2]/CO,N[sub 2]/CO[sub 2], 0[sub 2]/N[sub 2], and NH[sub 3]/N[sub 2] mixtures and for a variety of pure component gases (He, H[sub 2], CO[sub 2], N[sub 2], CO, NH[sub 3]). The most challenging part of the project turned out to be the sealing of the membrane at high temperatures and pressures. The report concludes with an overview of the practical potential of these membranes and of inorganic membranes in general of DOE and other applications.

  17. 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.

  18. FAS grafted superhydrophobic ceramic membrane

    International Nuclear Information System (INIS)

    The hydrophobic properties of γ-Al2O3 membrane have been obtained by grafting fluoroalkylsilane (FAS) on the surface of the membrane. The following grafting parameters were studied: the eroding time of the original membrane, the grafting time, the concentration of FAS solution and the multiplicity of grafting. Hydrophobicity of the membranes was characterized by contact angle (CA) measurement. The thermogravimetric analysis (TGA) was used to investigate the weight loss process (25-800 deg. C) of the fluoroalkylsilane grafted on Al2O3 powders under different grafting conditions. The morphologies of the membranes modified under different parameters were examined by field emission scanning electron microscopy (FE-SEM) and the surface roughness (Ra) was measured using white light interferometers. A needle-like structure was observed on the membrane surface after modification, which causes the change of Ra. On the results above, we speculated a model to describe the reaction between FAS and γ-Al2O3 membrane surface as well as the formed surface morphology.

  19. 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.

  20. 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...

  1. Membrane Duality Revisited

    CERN Document Server

    Duff, M J; Percacci, R; Pope, C N; Samtleben, H; Sezgin, E

    2015-01-01

    Just as string T-duality originates from transforming field equations into Bianchi identities on the string worldsheet, so it has been suggested that M-theory U-dualities originate from transforming field equations into Bianchi identities on the membrane worldvolume. However, this encounters a problem unless the target space has dimension $D = p + 1$. We identify the problem to be the nonintegrability of the U-duality transformation assigned to the pull-back map. Just as a double geometry renders manifest the $O(D,D)$ string T-duality, here we show in the case of the M2-brane in $D = 3$ that a generalised geometry renders manifest the $SL(3) \\times SL(2)$ U-duality. In the case of M2-brane in $D=4$, with and without extra target space coordinates, we show that only the ${\\rm GL}(4,R)\\ltimes R^4$ subgroup of the expected $SL(5,R)$ U-duality symmetry is realised.

  2. 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.

  3. Functional electrospun membranes

    Science.gov (United States)

    Ognibene, G.; Fragalà, M. E.; Cristaldi, D. A.; Blanco, I.; Cicala, G.

    2016-05-01

    In this study we combined electrospun PES nanofibers with ZnO nanostructures in order to obtain a hierarchical nanostructured hybrid material to be use for active water filtration membranes. It benefits of flexibility and high surface area of the polymeric nanofibers as well as of additional functionalities of ZnOnanostructures. First, randomly oriented nanofibers with diameters of 716nm ±365 nm were electrospun on a glass fibers substrate from a solution of PES and DMF-TOL(1:1). ZnO nanorods were grown onto the surface of electrospun PES fibers by a Chemical Bath Deposition (CBD) process. It was preceed by a seeding process necessary to form nucleation sites for the subsequent radially aligned growth of ZnO nanowires. The morfology of the fibers and the effect of the seeding time have been analysed by SEM. The amount of ZnO nanowires grown over electrospun nanofibers was determined as 45% by weight. The high purity and crystallinity of the asobtained products are confirmed by XRD since all reflection peaks can be indexed to hexagonal wurtzite ZnO.

  4. 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.

  5. 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...

  6. A membrane - foulant interaction study.

    OpenAIRE

    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-foaming agents (AFA) are by necessity widely used in the process industry. The severe problems during membrane filtration have been shown to be caused by AFA used in upstream process steps. AFA are amph...

  7. 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.

  8. Efficient preparation and analysis of membrane and membrane protein systems.

    Science.gov (United States)

    Javanainen, Matti; Martinez-Seara, Hector

    2016-10-01

    Molecular dynamics (MD) simulations have become a highly important technique to consider lipid membrane systems, and quite often they provide considerable added value to laboratory experiments. Rapid development of both software and hardware has enabled the increase of time and size scales reachable by MD simulations to match those attainable by several accurate experimental techniques. However, until recently, the quality and maturity of software tools available for building membrane models for simulations as well as analyzing the results of these simulations have seriously lagged behind. Here, we discuss the recent developments of such tools from the end-users' point of view. In particular, we review the software that can be employed to build lipid bilayers and other related structures with or without embedded membrane proteins to be employed in MD simulations. Additionally, we provide a brief critical insight into force fields and MD packages commonly used for membrane and membrane protein simulations. Finally, we list analysis tools that can be used to study the properties of membrane and membrane protein systems. In all these points we comment on the respective compatibility of the covered tools. We also share our opinion on the current state of the available software. We briefly discuss the most commonly employed tools and platforms on which new software can be built. We conclude the review by providing a few ideas and guidelines on how the development of tools can be further boosted to catch up with the rapid pace at which the field of membrane simulation progresses. This includes improving the compatibility between software tools and promoting the openness of the codes on which these applications rely. This article is part of a Special Issue entitled: Biosimulations edited by Ilpo Vattulainen and Tomasz Róg. PMID:26947184

  9. 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

  10. The appearance and clinical significance of persistent carotid-basilar artery anastomoses diagnosed by CT and MR angiography%永存颈内-基底动脉吻合血管的CTA、MRA 表现及临床意义

    Institute of Scientific and Technical Information of China (English)

    毛一朴; 马隆佰; 黄涛

    2015-01-01

    目的:探讨永存颈内-基底动脉吻合血管的 CT 血管造影(CTA)及 MR 血管造影(MRA)影像学表现并分析其临床意义。方法回顾性分析17例经头颈 CTA 及 MRA 诊断为永存颈内-基底动脉吻合血管患者的影像学资料。10例患者行头颈联合 CTA检查,7例患者行颅脑和颈部 MRA 检查,其中3例同时行 CTA 及 MRA 检查。结果永存三叉动脉(PTA)10例,按 Saltzman 分型:6例Ⅰ型,2例Ⅱ型,2例Ⅲ型。永存舌下动脉(PHA)3例,1例起始于右侧颈内动脉颈段,2例起始于左侧颈外动脉。寰前节间动脉(PIA)4例,2例位于右侧,2例位于左侧。1例 PTA 及1例 PHA 合并前交通动脉瘤。6例 PTA、2例 PHA 及1例 PIA 伴发基底动脉或椎动脉发育不良。结论CTA 及 MRA 能清楚显示永存颈内-基底动脉吻合血管的行程及其伴发颅内畸形血管合并症,为外科及介入手术提供准确的影像资料和指导作用。%Objective To explore the appearance of CT angiography(CTA)and magnetic resonance angiography (MRA)in persis-tent carotid-basilar artery anastomoses,and discuss its clinical significance.Methods 1 7 patients of persistent carotid-basilar artery anastomoses diagnosed by CT and MR angiography were retrospectively reviewed.10 patients were examined by craniocervical CTA, 7 patients were examined by cranial and cervical MRA,and 3 patients were examined by CTA and MRA.Results 10 patients had persistent trigeminal arteries (PTA).Based on Saltzman type:6 cases were Saltzman type Ⅰ,2 cases were Saltzman typeⅡ,and 2 cases were Saltzman type Ⅲ.1 case of 3 persistent hypoglossal arteries(PHA)originated from the right carotid artery,and 2 cases originated from the left external carotid artery.2 cases of 4 proatlantal intersegmental artery(PIA)were right ipsilateral,and 2 cases were left ipsilateral.1 case of PTA and 1 case of PHA associated with an aneurysm.6 cases of PTA,2 cases of PHA and 1 case of PIA complicated with ipsilateral

  11. 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 ...

  12. Characterization of polyacrylonitrile ultrafiltration membranes

    NARCIS (Netherlands)

    Germic, J.; Ebert, K.; Bouma, R.H.B.; Borneman, Z.; Mulder, M.H.V.; Strathmann, H.

    1997-01-01

    Various methods have been used to characterize ultrafiltration membranes, such as gas flux measurements, (field emission) scanning electron microscopy, permporometry and liquid-liquid displacement. Significant differences in the pore size distributions determined from permporometry and liquid-liquid

  13. 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.

  14. 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...

  15. Journal of Membrane Science & Research

    OpenAIRE

    Rathore, Narendra Singh; Sastre Requena, Ana María; Pabby, Anil Kumar

    2016-01-01

    Membrane assisted liquid extraction (MALE) technologies are gaining an important role as an extraction /separation technique for actinides and are being deployed as a promising tool for remediation of nuclear waste generated in the reprocessing plant and other radioactive wastes containing a trace level of radionuclides. The present contribution outlines the classification of membrane assisted liquid extraction techniques, its operating principle, associated transport mechanism and me...

  16. CO2 Acquisition Membrane (CAM)

    Science.gov (United States)

    Mason, Larry W.; Way, J. Douglas; Vlasse, Marcus

    2003-01-01

    The objective of CAM is to develop, test, and analyze thin film membrane materials for separation and purification of carbon dioxide (CO2) from mixtures of gases, such as those found in the Martian atmosphere. The membranes are targeted toward In Situ Resource Utilization (ISRU) applications that will operate in extraterrestrial environments and support future unmanned and human space missions. A primary application is the Sabatier Electrolysis process that uses Mars atmosphere CO2 as raw material for producing water, oxygen, and methane for rocket fuel and habitat support. Other applications include use as an inlet filter to collect and concentrate Mars atmospheric argon and nitrogen gases for habitat pressurization, and to remove CO2 from breathing gases in Closed Environment Life Support Systems (CELSS). CAM membrane materials include crystalline faujasite (FAU) zeolite and rubbery polymers such as silicone rubber (PDMS) that have been shown in the literature and via molecular simulation to favor adsorption and permeation of CO2 over nitrogen and argon. Pure gas permeation tests using commercial PDMS membranes have shown that both CO2 permeance and the separation factor relative to other gases increase as the temperature decreases, and low (Delta)P(Sub CO2) favors higher separation factors. The ideal CO2/N2 separation factor increases from 7.5 to 17.5 as temperature decreases from 22 C to -30 C. For gas mixtures containing CO2, N2, and Ar, plasticization decreased the separation factors from 4.5 to 6 over the same temperature range. We currently synthesize and test our own Na(+) FAU zeolite membranes using standard formulations and secondary growth methods on porous alumina. Preliminary tests with a Na(+) FAU membrane at 22 C show a He/SF6 ideal separation factor of 62, exceeding the Knudsen diffusion selectivity by an order of magnitude. This shows that the membrane is relatively free from large defects and associated non-selective (viscous flow) transport

  17. 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.

  18. 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.

  19. Multiscale Simulation of Protein Mediated Membrane Remodeling

    OpenAIRE

    Ayton, Gary S.; Voth, Gregory A.

    2009-01-01

    Proteins interacting with membranes can result in substantial membrane deformations and curvatures. This effect is known in its broadest terms as membrane remodeling. This review article will survey current multiscale simulation methodologies that have been employed to examine protein-mediated membrane remodeling.

  20. 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.

  1. Glasslike Membrane Protein Diffusion in a Crowded Membrane.

    Science.gov (United States)

    Munguira, Ignacio; Casuso, Ignacio; Takahashi, Hirohide; Rico, Felix; Miyagi, Atsushi; Chami, Mohamed; Scheuring, Simon

    2016-02-23

    Many functions of the plasma membrane depend critically on its structure and dynamics. Observation of anomalous diffusion in vivo and in vitro using fluorescence microscopy and single particle tracking has advanced our concept of the membrane from a homogeneous fluid bilayer with freely diffusing proteins to a highly organized crowded and clustered mosaic of lipids and proteins. Unfortunately, anomalous diffusion could not be related to local molecular details given the lack of direct and unlabeled molecular observation capabilities. Here, we use high-speed atomic force microscopy and a novel analysis methodology to analyze the pore forming protein lysenin in a highly crowded environment and document coexistence of several diffusion regimes within one membrane. We show the formation of local glassy phases, where proteins are trapped in neighbor-formed cages for time scales up to 10 s, which had not been previously experimentally reported for biological membranes. Furthermore, around solid-like patches and immobile molecules a slower glass phase is detected leading to protein trapping and creating a perimeter of decreased membrane diffusion. PMID:26859708

  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. 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.

  4. 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.

  5. 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. PMID:24976492

  6. 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

  7. Hydrophobic compounds reshape membrane domains.

    Directory of Open Access Journals (Sweden)

    Jonathan Barnoud

    2014-10-01

    Full Text Available Cell membranes have a complex lateral organization featuring domains with distinct composition, also known as rafts, which play an essential role in cellular processes such as signal transduction and protein trafficking. In vivo, perturbations of membrane domains (e.g., by drugs or lipophilic compounds have major effects on the activity of raft-associated proteins and on signaling pathways, but they are difficult to characterize because of the small size of the domains, typically below optical resolution. Model membranes, instead, can show macroscopic phase separation between liquid-ordered and liquid-disordered domains, and they are often used to investigate the driving forces of membrane lateral organization. Studies in model membranes have shown that some lipophilic compounds perturb membrane domains, but it is not clear which chemical and physical properties determine domain perturbation. The mechanisms of domain stabilization and destabilization are also unknown. Here we describe the effect of six simple hydrophobic compounds on the lateral organization of phase-separated model membranes consisting of saturated and unsaturated phospholipids and cholesterol. Using molecular simulations, we identify two groups of molecules with distinct behavior: aliphatic compounds promote lipid mixing by distributing at the interface between liquid-ordered and liquid-disordered domains; aromatic compounds, instead, stabilize phase separation by partitioning into liquid-disordered domains and excluding cholesterol from the disordered domains. We predict that relatively small concentrations of hydrophobic species can have a broad impact on domain stability in model systems, which suggests possible mechanisms of action for hydrophobic compounds in vivo.

  8. 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.

  9. Live cell imaging of membrane / cytoskeleton interactions and membrane topology

    Science.gov (United States)

    Chierico, Luca; Joseph, Adrian S.; Lewis, Andrew L.; Battaglia, Giuseppe

    2014-09-01

    We elucidate the interaction between actin and specific membrane components, using real time live cell imaging, by delivering probes that enable access to components, that cannot be accessed genetically. We initially investigated the close interplay between Phosphatidylinositol 4,5-bisphosphate (PIP2) and the F-actin network. We show that, during the early stage of cell adhesion, PIP2 forms domains within the filopodia membrane. We studied these domains alongside cell spreading and observed that these very closely follow the actin tread-milling. We show that this mechanism is associated with an active transport of PIP2 rich organelles from the cell perinuclear area to the edge, along actin fibers. Finally, mapping other phospholipids and membrane components we observed that the PIP2 domains formation is correlated with sphingosine and cholesterol rafts.

  10. Reconstitutions of mitochondrial inner membrane remodeling.

    Science.gov (United States)

    Barbot, Mariam; Meinecke, Michael

    2016-10-01

    Biological membranes exhibit function-related shapes, leading to a plethora of complex and beautiful cell and cell organellar morphologies. Most if not all of these structures have evolved for a particular physiological reason. The shapes of these structures are formed by physical forces that operate on membranes. To create particular shaped cells and cell organelles, membranes must undergo deformations which are determined by the structure and elasticity of the membrane and this process is most probable driven by proteins, lipids and/or interplay of both Zimmerberg and Kozlov (2006). Therefore, an important question of current cell biology in conjunction with physics and mathematics is to elucidate the functional cause for these different membrane morphologies as well as how they are formed. One of the most peculiar membrane shapes is observed in mitochondria. These organelles are surrounded by two membranes and especially the convoluted inner membrane displays a complex ultra-structure. A molecular understanding of how this membrane is shaped is missing to a large extent. Unlike membrane remodeling in classical curvature-dependent processes like clathrin-mediated endocytosis, mitochondria are most likely shaped by integral membrane proteins. Following, we will review the current knowledge of inner mitochondrial membrane architecture and discuss recent findings and advances in understanding the factors that shape this membrane. We will address pending questions especially with regard to the experimentally challenging nature of investigating membrane bending by hydrophobic integral membrane proteins. PMID:27456366

  11. Molecular dynamics of membrane proteins.

    Energy Technology Data Exchange (ETDEWEB)

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

    2004-10-01

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

  12. 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...

  13. 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.

  14. The effect of acute microgravity on mechanically-induced membrane damage and membrane-membrane fusion events

    Science.gov (United States)

    Clarke, M. S.; Vanderburg, C. R.; Feeback, D. L.; McIntire, L. V. (Principal Investigator)

    2001-01-01

    Although it is unclear how a living cell senses gravitational forces there is no doubt that perturbation of the gravitational environment results in profound alterations in cellular function. In the present study, we have focused our attention on how acute microgravity exposure during parabolic flight affects the skeletal muscle cell plasma membrane (i.e. sarcolemma), with specific reference to a mechanically-reactive signaling mechanism known as mechanically-induced membrane disruption or "wounding". Both membrane rupture and membrane resealing events mediated by membrane-membrane fusion characterize this response. We here present experimental evidence that acute microgravity exposure can inhibit membrane-membrane fusion events essential for the resealing of sarcolemmal wounds in individual human myoblasts. Additional evidence to support this contention comes from experimental studies that demonstrate acute microgravity exposure also inhibits secretagogue-stimulated intracellular vesicle fusion with the plasma membrane in HL-60 cells. Based on our own observations and those of other investigators in a variety of ground-based models of membrane wounding and membrane-membrane fusion, we suggest that the disruption in the membrane resealing process observed during acute microgravity is consistent with a microgravity-induced decrease in membrane order.

  15. 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...

  16. Challenges in commercializing biomimetic membranes

    DEFF Research Database (Denmark)

    Perry, Mark; Madsen, Steen Ulrik; Jørgensen, Tine Elkjær;

    2015-01-01

    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...... 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...... 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...

  17. 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.

  18. Membranous Dysmenorrhea: A Case Series

    Directory of Open Access Journals (Sweden)

    Hatim A. Omar

    2007-01-01

    Full Text Available The purpose was to illustrate the variability of hormonal contraception of patients that presented with membranous dysmenorrheal. A case analysis chart review was completed on six patients referred to a Pediatric Gynecologist in an academic setting. In each case the patient underwent a thorough pelvic and bimanual exam. Following the initial presentation, each patient continued to be followed on a regular visits. Cases: Two were using the transdermal contraceptive patch and oral contraceptive, but following the expulsion of decidual cast, they were both placed on depot medroxyprogesterone acetate (DMPA without further complications. Three of the six cases were on DMPA prior to the similar occurrence of membranous dysmenorrheal and following this incident, continued on DMPA without further problems. The final case was on the transdermal patch prior to decidual cast expulsion and remained on this form of hormonal contraception without further complications. These cases indicate that membranous dysmenorrheal is not limited to the use of DMPA.

  19. 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

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

    OpenAIRE

    Balster, Jörg Henning

    2006-01-01

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

  1. 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.

  2. High membrane permeability for melatonin.

    Science.gov (United States)

    Yu, Haijie; Dickson, Eamonn J; Jung, Seung-Ryoung; Koh, Duk-Su; Hille, Bertil

    2016-01-01

    The pineal gland, an endocrine organ in the brain, synthesizes and secretes the circulating night hormone melatonin throughout the night. The literature states that this hormone is secreted by simple diffusion across the pinealocyte plasma membrane, but a direct quantitative measurement of membrane permeability has not been made. Experiments were designed to compare the cell membrane permeability to three indoleamines: melatonin and its precursors N-acetylserotonin (NAS) and serotonin (5-HT). The three experimental approaches were (1) to measure the concentration of effluxing indoleamines amperometrically in the bath while cells were being dialyzed internally by a patch pipette, (2) to measure the rise of intracellular indoleamine fluorescence as the compound was perfused in the bath, and (3) to measure the rate of quenching of intracellular fura-2 dye fluorescence as indoleamines were perfused in the bath. These measures showed that permeabilities of melatonin and NAS are high (both are uncharged molecules), whereas that for 5-HT (mostly charged) is much lower. Comparisons were made with predictions of solubility-diffusion theory and compounds of known permeability, and a diffusion model was made to simulate all of the measurements. In short, extracellular melatonin equilibrates with the cytoplasm in 3.5 s, has a membrane permeability of ∼1.7 µm/s, and could not be retained in secretory vesicles. Thus, it and NAS will be "secreted" from pineal cells by membrane diffusion. Circumstances are suggested when 5-HT and possibly catecholamines may also appear in the extracellular space passively by membrane diffusion. PMID:26712850

  3. 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.

  4. 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...

  5. 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

  6. 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.

  7. Palaeontological evidence of membrane relationship in step-by-step membrane fusion

    OpenAIRE

    Wang, Xin; Liu, Wenzhe; DU, KAIHE

    2010-01-01

    Studies on membrane fusion in living cells indicate that initiation of membrane fusion is a transient and hard to capture process. Despite previous research, membrane behaviour at this point is still poorly understood. Recent palaeobotanical research has revealed snapshots of membrane fusion in a 15-million-year-old fossil pinaceous cone. To reveal the membrane behaviour during the fusion, we conducted more observations on the same fossil material. Several discernible steps of membrane fusion...

  8. Membrane biofilm development improves COD removal in anaerobic membrane bioreactor wastewater treatment

    OpenAIRE

    Smith, Adam L; Skerlos, Steven J; Raskin, Lutgarde

    2015-01-01

    Membrane biofilm development was evaluated to improve psychrophilic (15°C) anaerobic membrane bioreactor (AnMBR) treatment of domestic wastewater. An AnMBR containing three replicate submerged membrane housings with separate permeate collection was operated at three levels of membrane fouling by independently controlling biogas sparging for each membrane unit. High membrane fouling significantly improved permeate quality, but resulted in dissolved methane in the permeate at a concentration tw...

  9. A Systematic Assessment of Mature MBP in Membrane Protein Production: Overexpression, Membrane targeting and Purification

    OpenAIRE

    Hu, Jian; Qin, Huajun; Gao, Fei Philip; Cross, Timothy A

    2011-01-01

    Obtaining enough membrane protein in native or native-like status is still a challenge in membrane protein structure biology. Maltose binding protein (MBP) has been widely used as a fusion partner in improving membrane protein production. In the present work, a systematic assessment on the application of mature MBP (mMBP) for membrane protein overexpression and purification was performed on 42 membrane proteins, most of which showed no or poor expression level in membrane fraction fused with ...

  10. Resolution of Dialyzer Membrane-Associated Thrombocytopenia with Use of Cellulose Triacetate Membrane: A Case Report

    OpenAIRE

    Feyisayo Olafiranye; Win Kyaw; Oladipupo Olafiranye

    2011-01-01

    Blood and dialyzer membrane interaction can cause significant thrombocytopenia through the activation of complement system. The extent of this interaction determines the biocompatibility of the membrane. Although the newer synthetic membranes have been shown to have better biocompatibility profile than the cellulose-based membranes, little is known about the difference in biocompatibility between synthetic membrane and modified cellulose membrane. Herein, we report a case of a patient on hemo...

  11. Flux recovery of ceramic tubular membranes fouled with whey proteins: Some aspects of membrane cleaning

    OpenAIRE

    Popović Svetlana S.; Milanović Spasenija D.; Iličić Mirela D.; Lukić Nataša Lj.; Šijački Ivana M.

    2008-01-01

    Efficiency of membrane processes is greatly affected by the flux reduction due to the deposits formation at the surface and/or in the pores of the membrane. Efficiency of membrane processes is affected by cleaning procedure applied to regenerate flux. In this work, flux recovery of ceramic tubular membranes with 50 and 200 nm pore size was investigated. The membranes were fouled with reconstituted whey solution for 1 hour. After that, the membranes were rinsed with clean water and then cleane...

  12. Preparation of conductive membranes using poly pyrrole

    International Nuclear Information System (INIS)

    Conductive membranes show many benefits including fouling reduction for feeds containing ionic species. These membranes may be prepared either by conductive polymers or coating of the surfaces of non-conductive membranes with conductive polymer. In this research, the commercial micro filtration GVHP membrane manufactured from PVDF was coated with poly pyrrole using two different techniques. The conductivity of the prepared membranes was measured. In this paper, effects of various factors including concentration of the solutions, oxidizing agents, time for leaving the support in the solutions, support type and temperature on membrane conductivity were investigated

  13. 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.

  14. 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.

  15. 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.

  16. 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)

  17. Membranous nephropathy in sibling cats.

    Science.gov (United States)

    Nash, A S; Wright, N G

    1983-08-20

    Membranous nephropathy was diagnosed in two sibling cats from the same household. Both cases presented with the nephrotic syndrome but 33 months elapsed before the second cat became ill, by which time the first cat had been in full clinical remission for over a year. PMID:6623883

  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. 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)

  20. Current-Induced Membrane Discharge

    NARCIS (Netherlands)

    Baeko Andersen, M.; Soestbergen, M.; Mani, A.; Bruus, H.; Biesheuvel, P.M.; Bazant, M.Z.

    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

  1. 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.

  2. A Prize for Membrane Magic

    Science.gov (United States)

    Pfeffer, Suzanne R.

    2016-01-01

    The 2013 Nobel Prize in Physiology or Medicine has been awarded to James Rothman, Randy Schekman, and Thomas Südhof “for their discoveries of machinery regulating vesicle traffic, a major transport system in our cells”. I present a personal view of the membrane trafficking field, highlighting the contributions of these three Nobel laureates in a historical context. PMID:24315088

  3. Intelligent Membranes: Dream or Reality?

    Directory of Open Access Journals (Sweden)

    Annarosa Gugliuzza

    2013-07-01

    Full Text Available Intelligent materials are claimed to overcome current drawbacks associated with the attainment of high standards of life, health, security and defense. Membrane-based sensors represent a category of smart systems capable of providing a large number of benefits to different markets of textiles, biomedicine, environment, chemistry, agriculture, architecture, transport and energy. Intelligent membranes can be characterized by superior sensitivity, broader dynamic range and highly sophisticated mechanisms of autorecovery. These prerogatives are regarded as the result of multi-compartment arrays, where complementary functions can be accommodated and well-integrated. Based on the mechanism of “sense to act”, stimuli-responsive membranes adapt themselves to surrounding environments, producing desired effects such as smart regulation of transport, wetting, transcription, hydrodynamics, separation, and chemical or energy conversion. Hopefully, the design of new smart devices easier to manufacture and assemble can be realized through the integration of sensing membranes with wireless networks, looking at the ambitious challenge to establish long-distance communications. Thus, the transfer of signals to collecting systems could allow continuous and real-time monitoring of data, events and/or processes.

  4. Intelligent Membranes: Dream or Reality?

    Science.gov (United States)

    Gugliuzza, Annarosa

    2013-01-01

    Intelligent materials are claimed to overcome current drawbacks associated with the attainment of high standards of life, health, security and defense. Membrane-based sensors represent a category of smart systems capable of providing a large number of benefits to different markets of textiles, biomedicine, environment, chemistry, agriculture, architecture, transport and energy. Intelligent membranes can be characterized by superior sensitivity, broader dynamic range and highly sophisticated mechanisms of autorecovery. These prerogatives are regarded as the result of multi-compartment arrays, where complementary functions can be accommodated and well-integrated. Based on the mechanism of "sense to act", stimuli-responsive membranes adapt themselves to surrounding environments, producing desired effects such as smart regulation of transport, wetting, transcription, hydrodynamics, separation, and chemical or energy conversion. Hopefully, the design of new smart devices easier to manufacture and assemble can be realized through the integration of sensing membranes with wireless networks, looking at the ambitious challenge to establish long-distance communications. Thus, the transfer of signals to collecting systems could allow continuous and real-time monitoring of data, events and/or processes. PMID:26791465

  5. 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.

  6. A Prize for Membrane Magic

    OpenAIRE

    Pfeffer, Suzanne R.

    2013-01-01

    The 2013 Nobel Prize in Physiology or Medicine has been awarded to James Rothman, Randy Schekman, and Thomas Südhof “for their discoveries of machinery regulating vesicle traffic, a major transport system in our cells”. I present a personal view of the membrane trafficking field, highlighting the contributions of these three Nobel laureates in a historical context.

  7. Characterization of polyacrylonitrile ultrafiltration membranes

    OpenAIRE

    Germic, J.; Ebert, K.; Bouma, R.H.B.; Borneman, Z.; Mulder, M.H.V.; Strathmann, H.

    1997-01-01

    Various methods have been used to characterize ultrafiltration membranes, such as gas flux measurements, (field emission) scanning electron microscopy, permporometry and liquid-liquid displacement. Significant differences in the pore size distributions determined from permporometry and liquid-liquid displacement were found.

  8. Sintesis dan Karakterisasi Membran untuk Proses Ultrafiltrasi

    Directory of Open Access Journals (Sweden)

    Sri Aprilia

    2011-12-01

    Full Text Available Asymmetric ultrafiltration (UF membranes were prepared from three kinds of polymer namely polyacrilonitryle (PAN, polysufone (PS, and cellulose acetate (CA by phase inversion method. Water was used as non-solvent. These membranes were charachterized for ultrafiltration membranes i.e measurement of solvent permeability (Lp, Molecular Weight Cut Off membranes (MWCO with various molecular weight of solute dekstran, and morphology of the membrane by Scanning Electron Microscopy (SEM. SEM analysis includes surface area and cross section area. Membranes with polymer low concentration 10% as PAN-1, PS-1 and CA-1 have the larger Lp from PAN-2, PS-2, and CA-2 that have concentration 15%  for the same type of polymer. These occur because of the larger pore membrane than high concentration of polymer. SEM analysis showed a homogeneous distribution in the surface membrane and pore of membran like sponge structure from cross section area. Membranes CA-1, CA-2, FS-1 and FS-2 have Molecular Weight Cut off (MWCO for the solute dextran 40000 Da. For PS-2 and PS-2 membranes have MWCO of dextran above 20000 Da. Keywords: ultrafiltration membrane, solvent permeability coeficient, MWCO, membrane morphology

  9. Performance analysis of Air GapMembrane Distillation:Comparison of PTFE membranes : Comparison of PTFE membranes

    OpenAIRE

    Baaklini, Daniel

    2011-01-01

    Membrane Distillation (MD) is a very promising new technology which can be coupled with renewableenergies and/or waste heat to produce pure water at a low-cost. MD is extremely dependent upon theperformance of the membrane, as it dictates the mass transfer, the heat transfer and the long-termapplication. Unfortunately, there are no commercially produced MD-specific membranes at this point intime. This project aims at finding correlations between membrane characteristics and their performances...

  10. 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.

  11. 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.

  12. 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.

  13. Effective interactions between fluid membranes

    Science.gov (United States)

    Lu, Bing-Sui; Podgornik, Rudolf

    2015-08-01

    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 intermembrane separation d as d-2 for d ≪√{S } but crosses over to d-4 scaling for d ≫√{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 σ , which becomes small at low temperatures T and/or large bending stiffnesses κ . Moreover, σ scales as d for d ≪√{S } but saturates at √{kBT S /κ } for d ≫√{S } . In addition, using variational Gaussian theory, we apply our self-consistent treatment to study intermembrane interactions subject to different types of potentials: (i) the Moreira-Netz potential for a pair of strongly charged membranes with an intervening solution of multivalent counterions, (ii) an attractive square well, (iii) the Morse potential, and (iv) a combination of hydration and van der Waals interactions.

  14. 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.

  15. 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.

  16. 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.

  17. Bacterial cellulose membrane as separation medium

    Energy Technology Data Exchange (ETDEWEB)

    Shibazaki, Hideki; Kuga, Shigenori; Onabe, Fumihiko; Usuda, Makoto (Univ. of Toyko, (Japan). Faculty of Agriculture)

    1993-11-10

    A thin membrane of bacterial cellulose (BC) obtained from Acetobacter culture was tested for its performance as a dialysis membrane in aqueous systems. The BC membrane showed superior mechanical strength to that of a dialysis-grade regenerated cellulose membrane, allowing the use of a thinner membrane than the latter. As a result, the BC membrane gave higher permeation rates for poly(ethylene glycols) as probe solutes. The cutoff molecular weight of the original BC membrane, significantly greater than that of regenerated cellulose, could be modified by concentrated alkali treatments of the membrane. The nature of the change at the ultrastructural level caused by the alkali treatments was studied by X-ray diffraction and scanning electron microscopy.

  18. 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.

  19. Energy conservation employing membrane-based technology

    International Nuclear Information System (INIS)

    Membranes based processes, if properly adapted to industrial processes have good potential with regard to optimisation and economisation of energy consumption. The specific benefits of MBT (membrane based technology) as an energy conservation methodology are highlighted. (author). 6 refs

  20. Fuel-Cell Structure Prevents Membrane Drying

    Science.gov (United States)

    Mcelroy, J.

    1986-01-01

    Embossed plates direct flows of reactants and coolant. Membrane-type fuel-cell battery has improved reactant flow and heat removal. Compact, lightweight battery produces high current and power without drying of membranes.

  1. Acute endolymphatic hydrops has no direct effect on the vestibular evoked potential in the guinea pig

    NARCIS (Netherlands)

    Kingma, C. M.; Wit, H. P.

    2009-01-01

    To investigate the effect of an acute endolymphatic hydrops on the functioning of the vestibular system a hydrops was created by microinjection of artificial endolymph through the basilar membrane into scala media in 10 guinea pigs. To control for the effect of perforation of the basilar membrane, t

  2. A Model to Demonstrate the Place Theory of Hearing

    Science.gov (United States)

    Ganesh, Gnanasenthil; Srinivasan, Venkata Subramanian; Krishnamurthi, Sarayu

    2016-01-01

    In this brief article, the authors discuss Georg von Békésy's experiments showing the existence of traveling waves in the basilar membrane and that maximal displacement of the traveling wave was determined by the frequency of the sound. The place theory of hearing equates the basilar membrane to a frequency analyzer. The model described in this…

  3. Universal Behavior of Membranes with Sterols

    DEFF Research Database (Denmark)

    Henriksen, Jonas Rosager; Rowat, Amy C.; Brief, E.;

    2006-01-01

    the effects of cholesterol, lanosterol, and ergosterol on 1-palmitoyl-2- oleoyl-sn-glycero-3-phosphatidylcholine lipid bilayers at room temperature. Micropipette aspiration is used to determine membrane material properties (area compressibility modulus), and information about lipid chain order (first moments......) is obtained from deuterium nuclear magnetic resonance. We compare these results, along with data for membrane-bending rigidity, to explore the relationship between membrane hydrophobic thickness and elastic properties. Together, such diverse approaches demonstrate that membrane properties are affected...

  4. Anisotropic surface tension of buckled fluid membrane

    OpenAIRE

    Noguchi, Hiroshi

    2011-01-01

    Solid sheets and fluid membranes exhibit buckling under lateral compression. Here, it is revealed that fluid membranes have anisotropic buckling surface tension contrary to solid sheets. Surprisingly, the surface tension perpendicular to the buckling direction shows stronger dependence than that parallel to it. Our theoretical predictions are supported by numerical simulations of a meshless membrane model. This anisotropic tension can be used to measure the membrane bending rigidity. It is al...

  5. Lateral phase separation of confined membranes

    OpenAIRE

    Asfaw, Mesfin

    2010-01-01

    We consider membranes interacting via short, intermediate and long stickers. The effects of the intermediate stickers on the lateral phase separation of the membranes are studied via mean-field approximation. The critical potential depth of the stickers increases in the presence of the intermediate sticker. The lateral phase separation of the membrane thus suppressed by the intermediate stickers. Considering membranes interacting with short and long stickers, the effect of confinement on the ...

  6. Membrane bioreactor for waste gas treatment.

    OpenAIRE

    Reij, M W

    1997-01-01

    SummaryThis thesis describes the design and testing of a membrane bioreactor (MBR) for removal of organic pollutants from air. In such a bioreactor for biological gas treatment pollutants are degraded by micro-organisms. The membrane bioreactor is an alternative to other types of bioreactors for waste gas treatment, such as compost biofilters and bioscrubbers. Propene was used as a model pollutant to study the membrane bioreactor.A membrane bioreactor for waste gas treatment consists of a gas...

  7. Electrodiffusion of Lipids on Membrane Surfaces

    OpenAIRE

    Zhou, Y. C.

    2011-01-01

    Random lateral translocation of lipids and proteins is a universal process on membrane surfaces. Local aggregation or organization of lipids and proteins can be induced when this lateral random diffusion is mediated by the electrostatic interactions and membrane curvature. Though the lateral diffusion rates of lipids on membrane of various compositions are measured and the electrostatic free energies of predetermined protein-membrane-lipid systems can be computed, the process of the aggregati...

  8. Membrane processes in nuclear technologies

    International Nuclear Information System (INIS)

    The treatment of radioactive wastes is necessary taking into account the potential hazard of radioactive substances to human health and surrounding environment. The choice of appropriate technology depends on capital and operational costs, wastes amount and their characteristics, appointed targets of the process, e.g. the values of decontamination factors and volume reduction coefficients. The conventional technologies applied for radioactive waste processing, such as precipitation coupled with sedimentation, ion exchange and evaporation have many drawbacks. These include high energy consumption and formation of secondary wastes, e.g. the sludge from sediment tanks, spent ion exchange adsorbents and regeneration solutions. There are also many limitations of such processes, i.e. foaming and drop entrainment in evaporators, loses of solvents and production of secondary wastes in solvent extraction or bed clogging in ion exchange columns. Membrane processes as the newest achievement of the process engineering can successfully supersede many non-effective, out-of-date methods. But in some instances they can also complement these methods whilst improving the parameters of effluents and purification economy. This monograph presents own research data on the application of recent achievements in the area of membrane processes for solving selected problems in nuclear technology. Relatively big space was devoted to the use of membrane processing of low and intermediate radioactive liquid wastes because of numerous applications of these processes in nuclear centres over the world and also because of the interests of the author that was reflected by her recent research projects and activity. This work presents a review on the membrane methods recently introduced into the nuclear technology against the background of the other, commonly applied separation techniques, with indications of the possibilities and prospects for their further developments. Particular attention was paid

  9. Electro membrane extraction using sorbent filled porous membrane bag.

    Science.gov (United States)

    Naing, Nyi Nyi; Li, Sam Fong Yau; Lee, Hian Kee

    2015-12-01

    Electro membrane extraction-solid-liquid phase microextraction (EME-SLPME) was developed for the first time to determine phenolic contaminants in water. The extraction system consisted of a solid/liquid interface that permitted a three-phase microextraction approach involving an aqueous sample (donor phase): an organic solvent-sorbent within a membrane bag, and an organic solvent (extractant phase), operated in a direct immersion sampling system. The sorbent, reduced graphene oxide/polyvinyl alcohol, synthesized using graphene oxide and polyvinyl alcohol by dispersing the graphene oxide in polyvinyl alcohol and chemically reducing it in aqueous solution. The prepared sorbent was dispersed in 1-octanol and the solution was immobilized by sonication in the membrane bag wall pores which was in contact with the aqueous donor solution and organic extractant solvent (1-octanol) in the main bag itself. The analytes were transported by application of an electrical potential difference of 100V across the sorbent/solvent phase from the aqueous sample into the organic extractant phase in the membrane bag. After extraction and derivatization, gas chromatography-mass spectrometry was used to determine the derivatized analytes. This proposed EME-LSPME procedure provided high extraction efficiency with relative recoveries up to 99.6%. A linearity range of between 0.05 and 100μgL(-1) with corresponding coefficients of determination (r(2)) of between 0.987 and 0.996 were obtained. The limits of detection were in the range of between 0.003 and 0.053μgL(-1). This proposed method was successfully applied to the extraction of phenolic contaminants from water sample. PMID:26530143

  10. 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.

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

    Science.gov (United States)

    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 adding 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 two 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. PMID:19862919

  12. 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...

  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. 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

  15. 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-

  16. A Proteomics Approach to Membrane Trafficking

    NARCIS (Netherlands)

    Groen, A.J.; Vries, de S.C.; Lilley, K.S.

    2008-01-01

    Membrane trafficking, including that of integral membrane proteins as well as peripherally associated proteins, appears to be a vital process common to all eukaryotes. An important element of membrane trafficking is to determine the protein composition of the various endomembrane compartments. A maj

  17. Membrane domains and polarized trafficking of sphingolipids

    NARCIS (Netherlands)

    Maier, O; Slimane, TA; Hoekstra, D

    2001-01-01

    The plasma membrane of polarized cells consists of distinct domains, the apical and basolateral membrane that are characterized by a distinct lipid and protein content. Apical protein transport is largely mediated by (glyco)sphingolipid-cholesterol enriched membrane microdomains, so called rafts. In

  18. 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...

  19. Formation of asymmetric cellulose acetate membranes

    NARCIS (Netherlands)

    Bokhorst, H.; Altena, F.W.; Smolders, C.A.

    1981-01-01

    Cellulose acetate membranes were prepared from casting solutions containing dioxane as a solvent and varying concentrations (up to 6%) of maleic acid as an additive. Coagulation took place in water at different temperatures. The effect of these variables on membrane structure and membrane properties

  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. 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

  3. 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

  4. 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.

  5. 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

  6. 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.

  7. 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.

  8. 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...

  9. 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...

  10. 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...

  11. 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

  12. Air gap membrane distillation: 1. Modelling and mass transport properties for hollow fibre membranes

    NARCIS (Netherlands)

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

    2005-01-01

    A predictive model for air gap membrane distillation in a counter current flow configuration using fibre membranes is presented. The water vapour transport across the membrane is described by the dusty-gas model that uses constant membrane mass transport parameters to describe simultaneous Knudsen d

  13. 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.

  14. Denitrification using immersed membrane bioreactors

    OpenAIRE

    McAdam, Ewan J.

    2008-01-01

    Nitrate is practically ubiquitous in waters abstracted for municipal potable water production in Europe due to decades of intensive agricultural practice. Ion exchange is principally selected to target abstracted waters with elevated nitrate concentrations. However, the cost associated with disposal of the waste stream has re-ignited interest in destructive rather concentrative technologies. This thesis explores the potential of membrane bioreactor (MBR) technology for the remo...

  15. 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

  16. Membranes in Lithium Ion Batteries

    OpenAIRE

    Junbo Hou; Min Yang

    2012-01-01

    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 separa...

  17. 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.

  18. Mathematical modelling of membrane separation

    OpenAIRE

    Vinther, Frank; Brøns, Morten; Meyer, Anne S.

    2015-01-01

    Denne afhandling omhandler matematisk modellering af membranseparation. Afhandlingen består af indledende teori omhandlende membranseparation, ligninger fra fluiddynamik og egenskaber for dextran, som er det stof der ønskes separeret. Ydermere består den af tre separate matematiske modeller, med hver deres tilgang til membranseparation.Den første model er en statistisk model, som undersøger sammenhængen mellem molekyleform og sandsynligheden for at det givne molekyle penetrerer ind i membrane...

  19. Membrane Paradigm and Holographic Hydrodynamics

    Energy Technology Data Exchange (ETDEWEB)

    Eling, Christopher [SISSA, Via Bonomea 265, 34136 Trieste, Italy and INFN Sezione di Trieste, Via Valerio 2, 34127 Trieste (Italy); Neiman, Yasha; Oz, Yaron, E-mail: cteling@sissa.it, E-mail: yashula@gmail.com, E-mail: yaronoz@post.tau.ac.il [Raymond and Beverly Sackler School of Physics and Astronomy, Tel-Aviv University, Tel-Aviv 69978 (Israel)

    2011-09-22

    We discuss recent work showing that in certain cases the membrane paradigm equations governing the dynamics of black hole horizons can be recast as relativistic conservation law equations. In the context of gauge/gravity dualities, these equations are interpreted as defining the viscous hydrodynamics of a holographically dual relativistic field theory. Using this approach, one can derive the viscous transport coefficients and the form of the entropy current for field theories dual to gravity plus matter fields.

  20. Membrane Contact Sites: Complex Zones for Membrane Association and Lipid Exchange

    OpenAIRE

    Evan Quon; Beh, Christopher T.

    2016-01-01

    Lipid transport between membranes within cells involves vesicle and protein carriers, but as agents of nonvesicular lipid transfer, the role of membrane contact sites has received increasing attention. As zones for lipid metabolism and exchange, various membrane contact sites mediate direct associations between different organelles. In particular, membrane contact sites linking the plasma membrane (PM) and the endoplasmic reticulum (ER) represent important regulators of lipid and ion transfer...

  1. 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.

  2. Cholesterol organization in membranes at low concentrations: effects of curvature stress and membrane thickness.

    OpenAIRE

    Rukmini, R; Rawat, S S; Biswas, S. C.; Chattopadhyay, A

    2001-01-01

    Cholesterol is often found distributed nonrandomly in domains in biological and model membranes and has been reported to be distributed heterogeneously among various intracellular membranes. Although a large body of literature exists on the organization of cholesterol in plasma membranes or membranes with high cholesterol content, very little is known about organization of cholesterol in membranes containing low amounts of cholesterol. Using a fluorescent cholesterol analog (25-[N-[(7-nitrobe...

  3. Membrane lysis during biological membrane fusion: collateral damage by misregulated fusion machines

    OpenAIRE

    Engel, Alex; Walter, Peter

    2008-01-01

    In the canonical model of membrane fusion, the integrity of the fusing membranes is never compromised, preserving the identity of fusing compartments. However, recent molecular simulations provided evidence for a pathway to fusion in which holes in the membrane evolve into a fusion pore. Additionally, two biological membrane fusion models—yeast cell mating and in vitro vacuole fusion—have shown that modifying the composition or altering the relative expression levels of membrane fusion comple...

  4. Separation of metals by supported liquid membranes

    Energy Technology Data Exchange (ETDEWEB)

    Takigawa, D.Y.

    1990-12-31

    A supported liquid membrane system for the separation of a preselected chemical species within a feedstream, preferably an aqueous feedstream, includes a feed compartment containing a feed solution having at least one preselected chemical species therein, a stripping compartment containing a stripping solution therein, and a microporous polybenzimidazole membrane situated between the compartments, the microporous polybenzimidazole membrane containing an extractant mixture selective for the preselected chemical species within the membrane pores is disclosed along with a method of separating preselected chemical species from a feedstream with such a system, and a supported liquid membrane for use in such a system.

  5. Hydrodynamic approaches to reducing membrane fouling

    Energy Technology Data Exchange (ETDEWEB)

    Davis, R.H. [Univ. of Colorado, Boulder, CO (United States)

    1995-12-01

    Membranes are gaining increasing use in a wide variety of liquid and gas separations. A pervasive problem is membrane fouling due to material depositing on the membrane surface and within the membrane pore structure. Professor Georges Belfort has made significant contributions to reducing membrane fouling by hydrodynamic approaches for ultrafiltration and microfiltration. I will review some of his work, as well as related work by myself and others, in this area. Topics which will be discussed include particle migration during crossflow filtration, curved channels which promote centrifugal instabilities, and rapid backpulsing.

  6. 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.

  7. Gyroid Nanoporous Membranes with Tunable Permeability

    DEFF Research Database (Denmark)

    Li, Li; Schulte, Lars; Clausen, Lydia D.;

    2011-01-01

    Understanding the relevant permeability properties of ultrafiltration membranes is facilitated by using materials and procedures that allow a high degree of control on morphology and chemical composition. Here we present the first study on diffusion permeability through gyroid nanoporous cross....... The chemistry of 1,2-PB nanoporous membranes can be controlled, for example, by hydrophilic patterning of the originally hydrophobic membranes, which allows for different active porosity toward aqueous solutions and, therefore, different permeability. The membrane selectivity is evaluated by comparing...... for the presented gyroid nanoporous membranes....

  8. Membrane separation technology in the 1980s

    Science.gov (United States)

    Lonsdale, H. K.

    1982-01-01

    The current status of membrane technology is assessed and industrial processes in which membrane technology could effect energy savings or other advantages are identified. The extension of current trends is recommended; i.e., the development of ultrathin and highly permselective membranes, the use of specific carriers to enhance permselectivity and permit 'uphill' diffusion, and the improvement of separation efficiency. Membranes are predicted to be important in biotechnology and in the production of solar energy. Guidelines indicating where and how to look for opportunities where evolving membrane technology might fit are provided.

  9. Biomimetic aquaporin membranes coming of age

    DEFF Research Database (Denmark)

    Tang, Chuyang; Wang, Zhining; Petrinić, Irena;

    2015-01-01

    membranes, on the other hand, can perform transport in some cases with exceptional flux and rejection properties. In particular the discovery of selective water channel proteins - aquaporins - has prompted interest in using these proteins as building blocks for new types of membranes. The major challenge...... in developing an aquaporin-based membrane technology stems from the fact that the aquaporin protein spans a membrane only a few nanometers thick. Such ultrathin membranes will not be able to withstand any substantial pressures, nor being industrially scalable without supporting structures. Incorporating...

  10. 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.

  11. The role of cholesterol in membrane fusion.

    Science.gov (United States)

    Yang, Sung-Tae; Kreutzberger, Alex J B; Lee, Jinwoo; Kiessling, Volker; Tamm, Lukas K

    2016-09-01

    Cholesterol modulates the bilayer structure of biological membranes in multiple ways. It changes the fluidity, thickness, compressibility, water penetration and intrinsic curvature of lipid bilayers. In multi-component lipid mixtures, cholesterol induces phase separations, partitions selectively between different coexisting lipid phases, and causes integral membrane proteins to respond by changing conformation or redistribution in the membrane. But, which of these often overlapping properties are important for membrane fusion?-Here we review a range of recent experiments that elucidate the multiple roles that cholesterol plays in SNARE-mediated and viral envelope glycoprotein-mediated membrane fusion. PMID:27179407

  12. Silica nanoporous membranes and their applications

    Science.gov (United States)

    Khabibullin, Amir

    This thesis describes the development of novel silica and hybrid nanoporous membranes. Nanoporous membranes are widely used in various applications. This thesis focuses on their potential applications in the energy area, such as fuel cells and lithium batteries, and in separations and ultrafiltration. We use silica colloidal spheres and polymer-modified silica spheres to prepare the membranes in a time-, cost- and material-efficient manner. First, we prepared novel silica nanoporous membranes by pressing silica colloidal spheres followed by sintering. The pore size, the thickness, and the area of the membrane are precisely controlled by experiment parameters. The resulting membranes are mechanically and thermally durable, crack-free, and capable of size-selective transport. Next, to demonstrate the utility of the pressed membranes, described above, the proton-conductive pore-filled silica colloidal membranes were prepared and the fuel cells were constructed using these membranes. We modified these membranes by filling the membrane pores with surface-attached proton-conductive polymer brushes and prepared membrane-electrode assemblies to test fuel cell performance. We studied the proton conductivity and fuel cell performance as a function of the amount of sulfonic groups in the membrane. We also prepared and characterized reversible hybrid nanoporous membranes, self-assembled from solution containing polymer-modified silica colloidal spheres. Here we applied the new concept of noncovalent membranes, where the material is held together via noncovalent interactions of polymer brushes. This enables so-called reversible assembly of the membranes, in which membrane can be assembled in one solvent and dissolved in other. This approach provides advantages in recycling and reusing of the material. This work is one of the first of its kind and it opens a whole new area of research on reversible membranes made of polymer-modified nanoparticles. Finally, we applied our

  13. Surface selective membranes for carbon dioxide separation

    Energy Technology Data Exchange (ETDEWEB)

    Luebke, D.R.; Pennline, H.W.; Myers, C.R.

    2005-09-01

    In this study, hybrid membranes have been developed for the selective separation of CO2 from mixtures containing H2. Beginning with commercially available Pall alumina membrane tubes with nominal pore diameter of 5 nm, hybrids were produced by silation with a variety of functionalities designed to facilitate the selective adsorption of CO2 onto the pore surface. The goal is to produce a membrane which can harness the power of surface diffusion to give the selectivity of polymer membranes with the permeance of inorganic membranes.

  14. 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....

  15. 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.

  16. 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.

  17. Membrane potential and cancer progression

    Directory of Open Access Journals (Sweden)

    Ming eYang

    2013-07-01

    Full Text Available Membrane potential (Vm, the voltage across the plasma membrane, arises because of the presence of different ion channels/transporters with specific ion selectivity and permeability. Vm is a key biophysical signal in non-excitable cells, modulating important cellular activities, such as proliferation and differentiation. Therefore, the multiplicities of various ion channels/transporters expressed on different cells are finely tuned in order to regulate the Vm. It is well established that cancer cells possess distinct bioelectrical properties. Notably, electrophysiological analyses in many cancer cell types have revealed a depolarized Vm that favors cell proliferation. Ion channels/transporters control cell volume and migration, and emerging data also suggest that the level of Vm has functional roles in cancer cell migration. In addition, hyperpolarization is necessary for stem cell differentiation. For example, both osteogenesis and adipogenesis are hindered in human mesenchymal stem cells under depolarizing conditions. Therefore, in the context of cancer, membrane depolarization might be important for the emergence and maintenance of cancer stem cells, giving rise to sustained tumor growth. This review aims to provide a broad understanding of the Vm as a bioelectrical signal in cancer cells by examining several key types of ion channels that contribute to its regulation. The mechanisms by which Vm regulates cancer cell proliferation, migration and differentiation will be discussed. In the long term, Vm might be a valuable clinical marker for tumor detection with prognostic value, and could even be artificially modified in order to inhibit tumor growth and metastasis.

  18. 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 ...

  19. 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...

  20. 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%.

  1. Mechano-capacitive properties of polarized membranes.

    Science.gov (United States)

    Mosgaard, Lars D; Zecchi, Karis A; Heimburg, Thomas

    2015-10-28

    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, that treats capacitance, polarization, flexoelectricity, piezoelectricity and thermoelectricity in the same language. We show applications to electrostriction, membrane permeability and piezoelectricity and thermoelectricity close to melting transitions, where such effects are especially pronounced. PMID:26324950

  2. Dialysis membrane for separation on microchips

    Energy Technology Data Exchange (ETDEWEB)

    Singh, Anup K. (San Francisco, CA); Kirby, Brian J. (San Francisco, CA); Shepodd, Timothy J. (Livermore, CA)

    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.

  3. 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.

  4. Search for selective ion diffusion through membranes

    Science.gov (United States)

    May, C. E.; Philipp, W. H.

    1983-01-01

    The diffusion rates of several ions through some membranes developed as battery separators were measured. The ions investigated were Li(+), Rb(+), Cl(-), and So4. The members were crosslinked polyvinyl alcohol, crosslinked polyacrylic acid, a copolymer of the two, crosslinked calcium polyacrylate, cellulose, and several microporous polyphenylene oxide based films. No true specificity for diffusion of any of these ions was found for any of the membranes. But the calcium polyacrylate membrane was found to exhibit ion exchange with the diffusing ions giving rise to the leaching of the calcium ion and low reproducibility. These findings contrast earlier work where the calcium polyacrylate membrane did show specificity to the diffusion of the copper ion. In general, Fick's law appeared to be obeyed. Except for the microporous membranes, the coefficients for ion diffusion through the membranes were comparable with their values in water. For the microporous membranes, the values found for the coefficients were much less, due to the tortuosity of the micropores.

  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

    2012-02-14

    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. Biocatalytic Self-Cleaning Polymer Membranes

    Directory of Open Access Journals (Sweden)

    Agnes Schulze

    2015-09-01

    Full Text Available Polymer membrane surfaces have been equipped with the digestive enzyme trypsin. Enzyme immobilization was performed by electron beam irradiation in aqueous media within a one-step method. Using this method, trypsin was covalently and side-unspecific attached to the membrane surface. Thus, the use of preceding polymer functionalization and the use of toxic solvents or reagents can be avoided. The resulting membranes showed significantly improved antifouling properties as demonstrated by repeated filtration of protein solutions. Furthermore, the biocatalytic membrane can be simply “switched on” to actively degrade a fouling layer on the membrane surface and regain the initial permeability. The membrane pore structure (pore size and porosity was neither damaged by the electron beam treatment nor blocked by the enzyme loading, ensuring a stable membrane performance.

  9. 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.

  10. 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.

  11. 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.

  12. Membrane Domain Formation on Nanostructured Scaffolds

    Science.gov (United States)

    Collier, Charles; Liu, Fangjie; Srijanto, Bernadeta

    The spatial organization of lipids and proteins in biological membranes seems to have a functional role in the life of a cell. Separation of the lipids into distinct domains of greater order and anchoring to the cytoskeleton are two main mechanisms for organizing the membrane in cells. We propose a novel model membrane consisting of a lipid bilayer suspended over a nanostructured scaffold consisting of arrays of fabricated nanopillars. Unlike traditional model membranes, our model will have well-defined lateral structure and distributed substrate attachments that will emulate the connections of cellular membranes to the underlying cytoskeleton. Membranes will be characterized using neutron reflectometry, atomic force microscopy and fluorescence to verify a suspended, planar geometry with restricted diffusion at suspension points, and free diffusion in between. This architecture will allow the controlled study of lipid domain reorganization, viral infection and signal transduction that depend on the lateral structure of the membrane.

  13. 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.

  14. 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.

  15. 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.

  16. [Biomechanical characteristics of human fetal membranes. Preterm fetal membranes are stronger than term fetal membranes].

    Science.gov (United States)

    Rangaswamy, N; Abdelrahim, A; Moore, R M; Uyen, L; Mercer, B M; Mansour, J M; Kumar, D; Sawady, J; Moore, J J

    2011-06-01

    The purpose of this study was to determine the biomechanical characteristics of human fetal membranes (FM) throughout gestation. Biomechanical properties were determined for 115 FM of 23-41 weeks gestation using our previously described methodology. The areas of membrane immediately adjacent to the strongest and weakest tested spots were sampled for histomorphometric analysis. Clinical data on the patients whose FM were examined were also collected. FM less than 28 weeks gestation were associated with higher incidence of abruption and chorioamnionitis. Topographically FM at all gestations had heterogeneous biomechanical characteristics over their surfaces with distinct weak areas. The most premature membranes were the strongest. FM strength represented by rupture force and work to rupture decreased with increasing gestation in both weak and strong regions of FM. This decrease in FM strength was most dramatic at more than 38 weeks gestation. The FM component amnion-chorion sublayers were thinner in the weak areas compared to strong areas. Compared to term FM, preterm FM are stronger but have similar heterogeneous weak and strong areas. Following a gradual increase in FM weakness with increasing gestation, there is a major drop-off at term 38 weeks gestation. The FM weak areas are thinner than the stronger areas. Whether the difference in thickness is enough to account for the strength differences is unknown.

  17. The interaction between purple membrane and membrane lipid

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    Bacteriorhodopsin in purple membrane was reconstituted into different lipid vesicles. The effect of three different lipids on the structure and function of bacteriorhodopsin in lipid vesicles was studied by the observation on freeze-fracture eletron microscopy, the rotational diffusion of bacteriorhodopsin in lipid vesicles, the measurement of absorption spectrum, and the absorbance change with time. For these prepared samples, the results showed that DMPC was the stable lipid environment of bacteriorhodopsin; egg-pc causeed the loss of retinal chromophore of bacteriorhodopsin and it was not reversible change, cholesterol could stabilize the bacteriorhodopsin in lipid environment,but it caused the aggregation of bacteriorhodopsin.

  18. High flux and antifouling properties of negatively charged membrane for dyeing wastewater treatment by membrane distillation.

    Science.gov (United States)

    An, Alicia Kyoungjin; Guo, Jiaxin; Jeong, Sanghyun; Lee, Eui-Jong; Tabatabai, S Assiyeh Alizadeh; Leiknes, TorOve

    2016-10-15

    This study investigated the applicability of membrane distillation (MD) to treat dyeing wastewater discharged by the textile industry. Four different dyes containing methylene blue (MB), crystal violet (CV), acid red 18 (AR18), and acid yellow 36 (AY36) were tested. Two types of hydrophobic membranes made of polytetrafluoroethylene (PTFE) and polyvinylidene fluoride (PVDF) were used. The membranes were characterized by testing against each dye (foulant-foulant) and the membrane-dye (membrane-foulant) interfacial interactions and their mechanisms were identified. The MD membranes possessed negative charges, which facilitated the treatment of acid and azo dyes of the same charge and showed higher fluxes. In addition, PTFE membrane reduced the wettability with higher hydrophobicity of the membrane surface. The PTFE membrane evidenced especially its resistant to dye absorption, as its strong negative charge and chemical structure caused a flake-like (loose) dye-dye structure to form on the membrane surface rather than in the membrane pores. This also enabled the recovery of flux and membrane properties by water flushing (WF), thereby direct-contact MD with PTFE membrane treating 100 mg/L of dye mixtures showed stable flux and superior color removal during five days operation. Thus, MD shows a potential for stable long-term operation in conjunction with a simple membrane cleaning process, and its suitability in dyeing wastewater treatment. PMID:27486044

  19. Poly-thiosemicarbazide membrane for gold recovery

    KAUST Repository

    Villalobos, Luis Francisco

    2014-11-01

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

  20. Nanocrack-regulated self-humidifying membranes

    Science.gov (United States)

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

    2016-04-01

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

  1. Mechanical mysteries of bio-membranes

    Science.gov (United States)

    Parthasarathy, Raghuveer

    2010-10-01

    The membranes that form the boundaries of every cell and every organelle inside every cell are remarkable materials -- flexible, two-dimensional, self-assembled fluids. Exploring the ways in which these physical characteristics guide the biological functions of membranes has yielded many fascinating insights in recent years. I'll describe two projects from my lab in the area of membrane biophysics. One relates to the trafficking of cargo in cells, which involves dramatic changes in membrane shape and topography. By tugging on membranes with optical tweezers to measure their mechanical rigidity, we've found that a key trafficking protein has the ability to lower membrane rigidity by up to 100% as a function of its concentration, thereby lowering the energetic cost of membrane deformation. The other relates to the fluidity of membranes. By carefully examining the Brownian motion of membrane-anchored nanoparticles, we have found that membranes are not simple ``Newtonian'' fluids, but rather are viscoelastic -- a two-dimensional analogue of the entertaining grade-school staple of corn-starch and water. I'll stress in my talk the fascinating issues that invite exploration at the intersection of physics and biology, and some of the challenges involved in exploring them.

  2. Measuring shape fluctuations in biological membranes

    Science.gov (United States)

    Monzel, C.; Sengupta, K.

    2016-06-01

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

  3. Nanocrack-regulated self-humidifying membranes.

    Science.gov (United States)

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

    2016-04-28

    The regulation of water content in polymeric membranes is important in a number of applications, such as reverse electrodialysis and proton-exchange fuel-cell membranes. External thermal and water management systems add both mass and size to systems, and so intrinsic mechanisms of retaining water and maintaining ionic transport in such membranes are particularly important for applications where small system size is important. For example, in proton-exchange membrane fuel cells, where water retention in the membrane is crucial for efficient transport of hydrated ions, by operating the cells at higher temperatures without external humidification, the membrane is self-humidified with water generated by electrochemical reactions. Here we report an alternative solution that does not rely on external regulation of water supply or high temperatures. Water content in hydrocarbon polymer membranes is regulated through nanometre-scale cracks ('nanocracks') in a hydrophobic surface coating. These cracks work as nanoscale valves to retard water desorption and to maintain ion conductivity in the membrane on dehumidification. Hydrocarbon fuel-cell membranes with surface nanocrack coatings operated at intermediate temperatures show improved electrochemical performance, and coated reverse-electrodialysis membranes show enhanced ionic selectivity with low bulk resistance. PMID:27121841

  4. Nav Channels in Damaged Membranes.

    Science.gov (United States)

    Morris, C E; Joos, B

    2016-01-01

    Sick excitable cells (ie, Nav channel-expressing cells injured by trauma, ischemia, inflammatory, and other conditions) typically exhibit "acquired sodium channelopathies" which, we argue, reflect bleb-damaged membranes rendering their Nav channels "leaky." The situation is excitotoxic because untreated Nav leak exacerbates bleb damage. Fast Nav inactivation (a voltage-independent process) is so tightly coupled, kinetically speaking, to the inherently voltage-dependent process of fast activation that when bleb damage accelerates and thus left-shifts macroscopic fast activation, fast inactivation accelerates to the same extent. The coupled g(V) and availability(V) processes and their window conductance regions consequently left-shift by the same number of millivolts. These damage-induced hyperpolarizing shifts, whose magnitude increases with damage intensity, are called coupled left shift (CLS). Based on past work and modeling, we discuss how to test for Nav-CLS, emphasizing the virtue of sawtooth ramp clamp. We explain that it is the inherent mechanosensitivity of Nav activation that underlies Nav-CLS. Using modeling of excitability, we show the known process of Nav-CLS is sufficient to predict a wide variety of "sick excitable cell" phenomena, from hyperexcitability through to depolarizing block. When living cells are mimicked by inclusion of pumps, mild Nav-CLS produces a wide array of burst phenomena and subthreshold oscillations. Dynamical analysis of mild damage scenarios shows how these phenomena reflect changes in spike thresholds as the pumps try to counteract the leaky Nav channels. Smart Nav inhibitors designed for sick excitable cells would target bleb-damaged membrane, buying time for cell-mediated removal or repair of Nav-bearing membrane that has become bleb-damaged (ie, detached from the cytoskeleton). PMID:27586295

  5. Peptides that influence membrane topology

    Science.gov (United States)

    Wong, Gerard C. L.

    2014-03-01

    We examine the mechanism of a range of polypeptides that influence membrane topology, including antimicrobial peptides, cell penetrating peptides, viral fusion peptides, and apoptosis proteins, and show how a combination of geometry, coordination chemistry, and soft matter physics can be used to approach a unified understanding. We will also show how such peptides can impact biomedical problems such as auto-immune diseases (psoriasis, lupus), infectious diseases (viral and bacterial infections), and mitochondrial pathologies (under-regulated apoptosis leads to neurodegenerative diseases whereas over-regulated apoptosis leads to cancer.)

  6. Membranes Wrapped on Holomorphic Curves

    CERN Document Server

    Gauntlett, J P; Pakis, S; Waldram, D; Gauntlett, Jerome P.; Kim, Nakwoo; Pakis, Stathis; Waldram, Daniel

    2002-01-01

    We construct supergravity solutions dual to the twisted field theories arising when M-theory membranes wrap holomorphic curves in Calabi-Yau n-folds. The solutions are constructed in an Abelian truncation of maximal D=4 gauged supergravity and then uplifted to D=11. For four-folds and five-folds we find new smooth AdS/CFT examples and for all cases we analyse the nature of the singularities that arise. Our results provide an interpretation of certain charged topological AdS black holes. We also present the generalised calibration two-forms for the solutions.

  7. Thermostability of model protocell membranes

    OpenAIRE

    Mansy, Sheref S.; SZOSTAK, JACK W.

    2008-01-01

    The earliest cells may have consisted of a self-replicating genetic polymer encapsulated within a self-replicating membrane vesicle. Here, we show that vesicles composed of simple single-chain amphiphiles such as fatty acids, fatty alcohols, and fatty-acid glycerol esters are extremely thermostable and retain internal RNA and DNA oligonucleotides at temperatures ranging from 0°C to 100°C. The strands of encapsulated double-stranded DNA can be separated by denaturation at high temperature whil...

  8. Traveling-Wave Membrane Photomixers

    Science.gov (United States)

    Wyss, R. A.; Martin, S. C.; Nakamura, B. J.; Neto, A.; Pasqualini, D.; Siegel, P. H.; Kadow, C.; Gossard, A. C.

    2001-01-01

    Traveling-wave photomixers have superior performance when compared with lumped area photomixers in the 1 to 3 THz frequency range. Their large active area and distributed gain mechanism assure high thermal damage threshold and elimination of the capacitive frequency roll-off. However, the losses experienced by the radio frequency wave traveling along the coplanar strips waveguide (due to underlying semi-infinite GaAs substrate) were a serious drawback. In this paper we present device designs and an experimental setup that make possible the realization of photomixers on membranes which eliminate the losses.

  9. Study of Membrane Reflector Technology

    Science.gov (United States)

    Knapp, K.; Hedgepeth, J.

    1979-01-01

    Very large reflective surfaces are required by future spacecraft for such purposes as solar energy collection, antenna surfaces, thermal control, attitude and orbit control with solar pressure, and solar sailing. The performance benefits in large membrane reflector systems, which may be derived from an advancement of this film and related structures technology, are identified and qualified. The results of the study are reported and summarized. Detailed technical discussions of various aspects of the study are included in several separate technical notes which are referenced.

  10. POLYMER ELECTROLYTE MEMBRANE FUEL CELLS

    DEFF Research Database (Denmark)

    2001-01-01

    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....... With the thermally resistant polymer, e.g., polybenzimidazole or a mixture of polybenzimidazole and other thermoplastics as binder, the carbon-supported noble metal catalyst is tape-cast onto a hydrophobic supporting substrate. When doped with an acid mixture, electrodes are assembled with an acid doped solid...

  11. Mesoscopic models of biological membranes

    DEFF Research Database (Denmark)

    Venturoli, M.; Sperotto, Maria Maddalena; Kranenburg, M.;

    2006-01-01

    , as model systems to understand the fundamental properties of biomembranes. The properties of lipid bilayers can be studied at different time and length scales. For some properties it is sufficient to envision a membrane as an elastic sheet, while for others it is important to take into account the details...... of the individual atoms. In this review, we focus on an intermediate level, where groups of atoms are lumped into pseudo-particles to arrive at a coarse-grained, or mesoscopic, description of a bilayer, which is subsequently studied using molecular simulation. The aim of this review is to compare various strategies...

  12. Ceramic ultrafiltration membranes with photocatalytic properties

    Science.gov (United States)

    Bell, Deborah Wildman

    The photocatalytic properties of ceramic ultrafilters have been utilized in the development of a novel in-situ membrane cleaning process for ultrafiltration membranes fabricated from titania. The use of the photoactive membrane layer mitigates the effects of foulants in the system, thereby yielding an increase in the observed overall flux without sacrificing rejection of the solute by the membrane. Photocatalytic membranes of titania supported on porous tubes of alpha-alumina were fabricated using sol-gel techniques. These membranes were developed on the basis of the results of two-level factorial experimental designs. Electron microscopy and x-ray spectrometry were employed to evaluate coverage of the support by the membrane, the thickness of the membrane, and the presence of defects in the membrane. The photocatalytic membrane system was characterized to determine both morphological and performance parameters. Morphological parameters included the pore diameters, Darcy coefficients, and the individual resistances associated with each of the porous layers comprising the composite photocatalytic membrane. Performance parameters included the nominal molecular weight cutoff values of the ceramic membranes, the rate of permeation of pure solvent in the presence and the absence of UV illumination through the porous layers of interest, and the ability of the photocatalytic membrane to resist fouling and maintain permselectivity in the presence of UV illumination. The photocatalytic membranes were used to ultrafilter aqueous solutions of polymeric organic foulants present at an initial concentration of 1 x 10-3 M. Formation of a gel layer of foulant on the surface of the membrane was observed in the presence and in the absence of UV radiation; however, the results of permeability experiments indicated that formation of this foulant layer was significantly retarded (by a factor of two) in the presence of UV radiation. Improvement in the flow rate of permeate through the

  13. Bioinspired Multifunctional Membrane for Aquatic Micropollutants Removal

    DEFF Research Database (Denmark)

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

    2016-01-01

    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...... membrane, the multifunctional membrane exhibited significant improvement of BPA removal (78.21 ± 1.95%, 84.27 ± 7.30%, and 97.04 ± 0.33% for NT103, NF270, and NF90, respectively), all of which are clearly superior to the conventional Fenton treatment (55.0%) under similar conditions and comparable...... to soluble laccase coupled with NF270 membrane filtration (89.0%). The improvement would appear to be due to a combination of separation (reducing the enzymatic burden), adsorption (enriching the substrate concentration as well as prolonging the residence time), and lastly, catalysis (oxidizing...

  14. The plant plasma membrane H+-ATPase

    DEFF Research Database (Denmark)

    Ekberg, Kira

      The very high mobility of protons in aqueous solutions demands special features of membrane proton transporters to sustain efficient yet regulated proton transport across biological membranes. By the use of the chemical energy of ATP, plasma-membrane-embedded H+-ATPases extrude protons from cells...... of plants and fungi to generate electrochemical proton gradients. A recently published crystal structure of a plasma membrane H(+)-ATPase contributes to our knowledge about the mechanism of these essential enzymes. Together with biochemical and structural data presented in this thesis we are now able...... to describe the basic molecular components that allow the plasma membrane proton H+-ATPase to carry out proton transport against large membrane potentials. Moreover, a completely new paradigm for post-translational activation of these proteins is presented. The talk will focus on the following themes...

  15. Advanced membrane electrode assemblies for fuel cells

    Science.gov (United States)

    Kim, Yu Seung; Pivovar, Bryan S

    2014-02-25

    A method of preparing advanced membrane electrode assemblies (MEA) for use in fuel cells. A base polymer is selected for a base membrane. An electrode composition is selected to optimize properties exhibited by the membrane electrode assembly based on the selection of the base polymer. A property-tuning coating layer composition is selected based on compatibility with the base polymer and the electrode composition. A solvent is selected based on the interaction of the solvent with the base polymer and the property-tuning coating layer composition. The MEA is assembled by preparing the base membrane and then applying the property-tuning coating layer to form a composite membrane. Finally, a catalyst is applied to the composite membrane.

  16. 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......-Pearson condition.Molecularly based models such as the neo-Hookean, Doi-Edwardsor Pom-Pom models, as well as the network model recently proposed byMarrucci, exhibit a pressure maximum when inflated. Membranesdescribed by these models develop local thinningwhich may lead to bursting in finite time.Chain branching...

  17. Method of fabrication of supported liquid membranes

    Energy Technology Data Exchange (ETDEWEB)

    Luebke, David R.; Hong, Lei; Myers, Christina R.

    2015-11-17

    Method for the fabrication of a supported liquid membrane having a dense layer in contact with a porous layer, and a membrane liquid layer within the interconnected pores of the porous layer. The dense layer is comprised of a solidified material having an average pore size less than or equal to about 0.1 nanometer, while the porous layer is comprised of a plurality of interconnected pores and has an average pore size greater than 10 nanometers. The supported liquid membrane is fabricated through the preparation of a casting solution of a membrane liquid and a volatile solvent. A pressure difference is established across the dense layer and porous layer, the casting solution is applied to the porous layer, and the low viscosity casting solution is drawn toward the dense layer. The volatile solvent is evaporated and the membrane liquid precipitates, generating a membrane liquid layer in close proximity to the dense layer.

  18. Properties of Polyethylene Naphthalate Track Membranes

    CERN Document Server

    Akimenko, S N; Orelovich, O L; Maekawa, J; Ioshida, M; Apel, P Yu

    2002-01-01

    Basic characteristics of track membranes made of polyethylene naphthalate (which is a polyester synthesized from dimethyl naphthalate and ethylene glycol) are studied and presented. Polyethylene naphthalate possesses some properties (mechanical strength, thermal and chemical stability), which make this polymer a promising material for the production of track membranes. Water flow rate and air flow rate characteristics, burst strength, wettability, and amount of extractables are determined. Surface structure and pore structure are examined using scanning electron microscopy. It is found that the pores in the membranes are cylindrical in shape. The measured water and air flow rates follow known theoretical relations for the transport in narrow capillaries. The burst strength of polyethylene naphthalate membranes is found to be similar to that of polyethylene terephthalate track membranes. Polyethylene naphthalate track membranes can be categorized as moderately hydrophilic. Being treated with boiling water, pol...

  19. Biophysical studies of membrane channel polypeptides

    CERN Document Server

    Galbraith, T P

    2001-01-01

    Membrane channels facilitate the flow of ions across biological membranes, a process which is important in numerous cellular functions. The study of large integral membrane proteins is made difficult by identification, production and purification problems, and detailed knowledge of their three-dimensional structures is relatively scarce. The study of simple 'model' membrane proteins has given valuable insight into the structures and dynamics of membrane proteins in general. The bacterial peptide gramicidin has been the subject of intense study for many years, and has provided important information into the structural basis of channel function. Peptaibols, a class of fungal membrane peptides which includes alamethicin and antiamoebin, have also been useful in relating structural details to molecular ion transport processes. Gramicidin crystals were grown in the presence of phospholipids with various headgroups and acyl chains. The diffraction patterns of the crystals obtained were processed, but found to be in...

  20. Porous polyoxadiazole membranes for harsh environment

    KAUST Repository

    Maab, Husnul

    2013-10-01

    A series of polyoxadiazoles with exceptionally high stability at temperatures as high as 370°C and in oxidative medium has been synthesized by polycondensation and manufactured into porous membranes by phase inversion. The membranes were characterized by thermal analysis (TGA), chemical stability was measured by immersion test, oxidative stability by Fenton\\'s test, pore diameter by porosimetry and the morphology by FESEM. The polymers are soluble only in sulfuric acid and are stable in organic solvents like NMP, THF and isopropanol. The membranes selectivity was confirmed by separation of polystyrene standards with different molecular weights. Most membranes were characterized as having a cut-off of 60,000. g/mol. Being stable under harsh environments, the membranes have incomparable characteristics with perspectives of application in chemical and pharmaceutical industry, catalytic reactors, in combination with oxidative processes and other applications so far envisioned only for ceramic membranes. © 2013.