WorldWideScience

Sample records for chorioallantoic membrane

  1. Structural Analysis of the Angiogenesis in the Chicken Chorioallantoic Membrane

    OpenAIRE

    Verhoelst, Eva

    2011-01-01

    During the last decades, the poultry sector is in search of ways to monitor chicken embryonic growth, health and quality, as to control and optimize the incubation conditions, especially the gas concentrations. One of the parameters of chicken development which may change under different gas concentrations is the angiogenesis in the chorioallantoic membrane (CAM), the organ for gas exchange of the chicken embryo. To be able to perform large incubation experiments under different gaseous condi...

  2. Targeted labeling of early-​stage tumor spheroid in chorioallantoic membrane model with upconversion nanoparticles

    NARCIS (Netherlands)

    K. Liu; J.A. Holz; Y. Ding; X. Liu; Y. Zhang; L. Tu; X. Kong; B. Priem; A. Nadort; S.A.G. Lambrechts; M.C.G. Aalders; W.J. Buma; Y. Liu; H. Zhang

    2015-01-01

    In vivo detection of cancer at early-​stage, i.e. smaller than 2 mm, is a challenge in biomedicine. In this work target labeling of early-​stage tumor spheroid (∼500 μm) is realized for the first time in chick embryo chorioallantoic membrane (CAM) model with monoclonal antibody functionalized upconv

  3. High-resolution Magnetic Resonance Imaging analysis of breast cancer xenograft on the chick chorioallantoic membrane

    OpenAIRE

    ZUO, ZHI

    2015-01-01

    In this thesis an age-adapted cooling regime for immobilization of the chick embryo is proposed. Reliable immobilization completely avoided motion artifacts, enabling high resolution magnetic resonance imaging (MRI) of the chicken embryo and also tumor xenograft on the chorioallantoic membrane (CAM). Tumor growth monitoring was firstly evaluated after xenotransplantation of MDA-MB-231 cells on the CAM. Tumor volumes were monitored from day 4 to day 9 after grafting applying a T2-weighted R...

  4. Preliminary investigation of Angiogenic property of Ethanolic leaf extract of Acyranthus Aspera using chorioallantoic membrane model

    Directory of Open Access Journals (Sweden)

    K. Hema Kumar

    2015-10-01

    Full Text Available The present study is an attempt to investigate the angiogenic property of ethanolic leaf extract of Achyranthus aspera by in vitro, Hen's Egg Chorioallantoic Membrane method (HET-CAM. Ethanolic leaf extract of Achyranthus aspera treated CAM showed increased density of new blood capillaries as compared with control group treated with 0.9% Nacl. The results obtained in this study suggest that the Achyranthes aspera leaf extract revealed a significant scope to develop a novel broad spectrum of herbal formulations for wound healing and different herbal formulations

  5. Use of In Ovo Chorioallantoic Membrane Engraftment to Culture Testes from Neonatal Mice

    OpenAIRE

    Uematsu, Emi; Takino, Sachio; Okajima, Hidemi; Tong, Bin; Sugiyama, Toshie; Yamada, Takahisa; Niimura, Sueo; Yamashiro, Hideaki

    2014-01-01

    Many attempts have been made to culture germ cells in vitro by mimicking their development in vivo. The objective of this study was to establish an alternative method of xenotransplantation by developing a new approach for the rapid induction of spermatogenesis by using the chorioallantoic membrane of developing chicken embryos. Fertilized chicken eggs were incubated for 7 d, after which a small window was cut into the shell of the egg. We then transplanted testes from 7- to 8-d-old B6D2F1 mi...

  6. In Ovo PET Imaging Of A Human Colorectal Carcinoma Model In Chicken Chorioallantoic Membrane

    OpenAIRE

    Warnock, Geoffrey; Turtoi, Andrei; Blomme, Arnaud; Gonzalez, Arnaud; Bretin, Florian; Bahri, Mohamed Ali; Lemaire, Christian; Seret, Alain; Castronovo, Vincenzo; Luxen, André; Plenevaux, Alain

    2012-01-01

    Aim. The objective of this study was to use in vivo PET/CT imaging as a validation tool for a novel human colorectal carcinoma model being developed in chicken chorioallantoic membrane (CAM). For this initial pilot study a cell line modeling colon cancer was selected and imaged using [18F]fluorodeoxyglucose (FDG). Materials and methods. A window was made in the shell of fertilized chicken eggs and 3x106 SW1222 human colorectal carcinoma cells were implanted at day 10 post-fertilization. On...

  7. Organochlorine pesticides in chorioallantoic membranes of Morelet's crocodile eggs from belize.

    Science.gov (United States)

    Pepper, Christopher B; Rainwater, Thomas R; Platt, Steven G; Dever, Jennifer A; Anderson, Todd A; McMurry, Scott T

    2004-07-01

    Recent studies examined the utility of the chorioallantoic membrane (CAM) as a nonlethal, noninvasive indicator of environmental contaminant exposure in oviparous wildlife. The CAM is a highly vascularized extraembryonic membrane that functions as a site for respiration, nutrient transport, and waste storage during embryonic development. After hatching, the CAM is usually discarded with the eggshell and can be used for chemical residue analysis. Chorioallantoic membranes have been used successfully to examine contaminant exposure and predict chemical concentrations in multiple species of birds and reptiles. In this study, we examined organochlorine (OC) pesticide concentrations in CAMs from eggs of Morelet's crocodiles (Crocodylus moreletii) from northern Belize. Multiple OCs were detected in crocodile CAMs, including aldrin, dieldrin, endrin, dichlorodiphenyltrichloroethane, dichlorodiphenyldichloroethane, dichlorodiphenyldichloroethylene (DDE), heptachlor, lindane, and methoxychlor. Number and concentrations of OC compounds in CAMs were variable. The most prevalent contaminant detected was DDE, which occurred in 69% of CAMs, with concentrations ranging from 0.3 parts per billion (ppb) to 17.0 ppb. The OC burdens in crocodile CAMs confirm contamination of eggs and suggest exposure in embryos and maternal females. These results further support the use of CAMs as qualitative indicators of OC exposure in oviparous wildlife. The efficacy of this sampling technique in the field will depend on the logistics and cost associated with CAM collection and the specific life history traits of the wildlife species. PMID:15465717

  8. Targeted labeling of an early-stage tumor spheroid in a chorioallantoic membrane model with upconversion nanoparticles

    NARCIS (Netherlands)

    K. Liu; J.A. Holz; Y. Ding; X. Liu; Y. Zhang; L. Tu; X. Kong; B. Priem; A. Nadort; S.A.G. Lambrechts; M.C.G. Aalders; W.J. Buma; Y. Liu; H. Zhang

    2015-01-01

    In vivo detection of cancer at an early-stage, i.e. smaller than 2 mm, is a challenge in biomedicine. In this work target labeling of an early-stage tumor spheroid (similar to 500 mu m) is realized for the first time in a chick embryo chorioallantoic membrane (CAM) model with monoclonal antibody fun

  9. Quantitative measurement of blood flow dynamics in chorioallantoic membrane of chicken embryo using laser Doppler anemometry

    Science.gov (United States)

    Borozdova, M. A.; Stiukhina, E. S.; Sdobnov, A. A.; Fedosov, I. V.; Postnov, D. E.; Tuchin, V. V.

    2016-04-01

    We report the results on in ovo application of developed Laser Doppler Anemometer (LDA) device. The chorioallantoic membrane (CAM) of 9-13 days chicken embryos was used as a biological model that allows an easy access to both arterial and venous vessels of different size. The key point of our study was to find out how the periodic and aperiodic pulsations of blood flow (which are inevitable in living organism) will affect the LDA functions and measuring capability. Specifically, we (i) developed the technique to extract and refine the pulse rhythm from the signal received from a vessel, and (ii) analyzed the changes in power spectra of LDA signal that are caused by heart beating and considerably complicate the reliable measurement of Doppler shift. Our main conclusion is that the algorithm of LDA data processing need to be improved, and this possibly can be done by counting the information on current phase of cardiac cycle.

  10. Proteomic Profile of Brucella abortus-Infected Bovine Chorioallantoic Membrane Explants

    Science.gov (United States)

    Mol, Juliana P. S.; Pires, Simone F.; Chapeaurouge, Alexander D.; Perales, Jonas; Santos, Renato L.; Andrade, Hélida M.; Lage, Andrey P.

    2016-01-01

    Brucella abortus is the etiological agent of bovine brucellosis, a zoonotic disease that causes significant economic losses worldwide. The differential proteomic profile of bovine chorioallantoic membrane (CAM) explants at early stages of infection with B. abortus (0.5, 2, 4, and 8 h) was determined. Analysis of CAM explants at 0.5 and 4 h showed the highest differences between uninfected and infected CAM explants, and therefore were used for the Differential Gel Electrophoresis (DIGE). A total of 103 spots were present in only one experimental group and were selected for identification by mass spectrometry (MALDI/ToF-ToF). Proteins only identified in extracts of CAM explants infected with B. abortus were related to recognition of PAMPs by TLR, production of reactive oxygen species, intracellular trafficking, and inflammation. PMID:27104343

  11. Use of in ovo chorioallantoic membrane engraftment to culture testes from neonatal mice.

    Science.gov (United States)

    Uematsu, Emi; Takino, Sachio; Okajima, Hidemi; Tong, Bin; Sugiyama, Toshie; Yamada, Takahisa; Niimura, Sueo; Yamashiro, Hideaki

    2014-08-01

    Many attempts have been made to culture germ cells in vitro by mimicking their development in vivo. The objective of this study was to establish an alternative method of xenotransplantation by developing a new approach for the rapid induction of spermatogenesis by using the chorioallantoic membrane of developing chicken embryos. Fertilized chicken eggs were incubated for 7 d, after which a small window was cut into the shell of the egg. We then transplanted testes from 7- to 8-d-old B6D2F1 mice onto the vessels of the chorioallantoic membrane and incubated them at 35.0 °C for 14 d or 37.5 °C for 12 d. After this in ovo CAM (iCAM) culture, the survival rates of the eggs and testes were assessed histologically and immunohistologically. The transplanted testes in the chicken embryos that survived were supported by the CAM, with an associated chronic vascularization response. The testes cultured at 35.0 °C had lower rates of generation and higher rates of death than did those cultured at 37.5 °C. Histologic examination of the testes cultured at 37.5 °C revealed the presence of spermatogonia and primary spermatocyte-like germ cells in the seminiferous tubules. The number of cells positive for synaptonemal complex protein 3 in the seminiferous tubules was significantly higher than that in the noniCAM-cultured testes from control mice. These results suggest that iCAM culturing of neonatal donor testis induces androcyte development. This method could be the foundation for a method that would enable in vitro spermatogenesis. PMID:25296013

  12. Regulation of Vascular Growth in the Chorioallantoic Membrane of Japanese Quail Eggs

    Science.gov (United States)

    Montague, Idoreyin P.

    2004-01-01

    The Microgravity Research Program is part of NASA's Office of Biological and Physical Research (OBPR). The mission of the Microgravity Fluid Physics research program is to facilitate and conduct the best possible fluid physics research using the space environment and make this knowledge available to the scientific community and the public at large. During the summer of 2004, I worked in this division with Dr. Patricia Parsons-Wingerter. Dr. Parsons was working on several projects that used the chorioallantoic membrane (CAM) of Japanese quail eggs. The CAM develops in the eggs of birds and reptiles and is a very vascular fetal membrane composed of the fused chorion and adjacent wall of the allantois. The CAM is formed on day 4 of incubation and its primary job is to mediate gas exchanges with the extra embryonic environment. The CAM of our Japanese quail eggs is easily identifiable to us because it is transparent and it sits on top of the yolk with the embryo in the center. The CAM is of interest because of its many applications in the field of medicine as it relates to vascular remodeling and angiogenesis. Angiogenesis is simply the growth or formation of new blood vessels and anti-angiogenesis is the inhibition of said vessels. Angiogenesis occurs naturally in a healthy body for healing wounds and for restoring blood flow to tissues after injury and in females during the monthly reproductive cycle. In many serious diseases, like several types of cancer and those that affect the heart and cardiovascular system, the body loses control over angiogenesis. These diseases, which are dependent on angiogenesis, result when new blood vessels either grow excessively or insufficiently. The chorioallantoic membrane of our Japanese quail eggs gives a good model of angiogenesis. We used angiogenic regulators to inhibit or stimulate vascular growth in the CAM in a healthy manner and they induced distinct vascular patterns in vivo. Certain dominant regulators can be recognized by

  13. Viola tricolor Induces Apoptosis in Cancer Cells and Exhibits Antiangiogenic Activity on Chicken Chorioallantoic Membrane

    Directory of Open Access Journals (Sweden)

    Hamid Reza Sadeghnia

    2014-01-01

    Full Text Available In the present study, the cytotoxic and apoptogenic properties of hydroalcoholic extract and ethyl acetate (EtOAc, n-butanol, and water fractions (0–800 μg/mL of Viola tricolor were investigated in Neuro2a mouse neuroblastoma and MCF-7 human breast cancer cells. In addition, antiangiogenic effect of EtOAc fraction was evaluated on chicken chorioallantoic membrane (CAM. The quality of EtOAc fraction was also characterized using high performance liquid chromatography (HPLC fingerprint. Cytotoxicity assay revealed that EtOAc fraction was the most potent among all fractions with maximal effect on MCF-7 and minimal toxicity against normal murine fibroblast L929 cells. Apoptosis induction by EtOAc fraction was confirmed by increased sub-G1 peak of propidium iodide (PI stained cells. This fraction triggered the apoptotic pathway by increased Bax/Bcl-2 ratio and cleaved caspase-3 level. Moreover, treatment with EtOAc fraction significantly decreased the diameter of vessels on CAM, while the number of newly formed blood vessels was not suppressed significantly. Analysis of quality of EtOAc fraction using HPLC fingerprint showed six major peaks with different retention times. The results of the present study suggest that V. tricolor has potential anticancer property by inducing apoptosis and inhibiting angiogenesis.

  14. The human skin/chick chorioallantoic membrane model accurately predicts the potency of cosmetic allergens.

    Science.gov (United States)

    Slodownik, Dan; Grinberg, Igor; Spira, Ram M; Skornik, Yehuda; Goldstein, Ronald S

    2009-04-01

    The current standard method for predicting contact allergenicity is the murine local lymph node assay (LLNA). Public objection to the use of animals in testing of cosmetics makes the development of a system that does not use sentient animals highly desirable. The chorioallantoic membrane (CAM) of the chick egg has been extensively used for the growth of normal and transformed mammalian tissues. The CAM is not innervated, and embryos are sacrificed before the development of pain perception. The aim of this study was to determine whether the sensitization phase of contact dermatitis to known cosmetic allergens can be quantified using CAM-engrafted human skin and how these results compare with published EC3 data obtained with the LLNA. We studied six common molecules used in allergen testing and quantified migration of epidermal Langerhans cells (LC) as a measure of their allergic potency. All agents with known allergic potential induced statistically significant migration of LC. The data obtained correlated well with published data for these allergens generated using the LLNA test. The human-skin CAM model therefore has great potential as an inexpensive, non-radioactive, in vivo alternative to the LLNA, which does not require the use of sentient animals. In addition, this system has the advantage of testing the allergic response of human, rather than animal skin. PMID:19054059

  15. Automated computational framework of blood vessel quantification in chick chorioallantoic membrane angiogenesis.

    Science.gov (United States)

    Shi, Peng; Hong, Jinsheng; Huang, Yue; Zhang, Zhenhuan; Zhang, Mei; Zhang, Lurong

    2014-01-01

    Chick chorioallantoic membrane (CAM) angiogenesis assay has been widely used for finding drugs targeting new blood vessel development in cancer research. In addition to the setup materials and protocols, laboratory findings depend on the quantification and analysis of microscopic blood vessel images. However, it is still a challenging problem because of the high complexity of blood vessel branching structures. We applied preprocessing on CAM microscopic images by keeping the integrity of minor branches in the vessel structure. We then proposed an efficient way to automatically extract blood vessel centerlines based on vector tracing starting from detected seed points. Finally, all branches were coded to construct an abstract model of the branching structure, which enabled more accurate modeling for in-depth analysis. The framework was applied in quantifying Icaritin (ICT) inhibition effects on angiogenesis in a CAM model. Experimental results showed the high accuracy in blood vessel quantification and modeling compared with semimanual measurements. Meanwhile, a set of blood vessel growth indicators were extracted to provide fully automated analysis for angiogenesis assays. Further analysis proved that ICT took effect in a dose-dependent manner which could be applied in suppressing tumor blood vessel growth. PMID:25277148

  16. Photodynamic damage to cartilage and synovial tissue grafted on a chick's chorioallantoic membrane

    Science.gov (United States)

    Fisher, M.; Nahir, A. M.; Kimel, Sol

    1997-09-01

    Rheumatoid arthritis (RA) is a chronic inflammatory disease of the synovial joints causing pain deformities and disability. The highly vascular inflamed synovium has aggressive and destructive characteristics, it invades, erodes and gradually destroys cartilage and underlying bone. Photodynamic therapy (PDT) was performed using the chick chorioallantoic membrane (CAM) model to investigate the vitality of synovium and cartilage implanted on the CAM. Synovium, obtained from human patients, was grafted onto the CAM; gross microscopy and histology proved its vitality 7 days post grafting. Cartilage obtained from rabbit knee joint was also maintained on the CAM for 7 days. Its vitality was demonstrated by histology and by measuring metabolic and enzymatic activity of cartilage cells (chondrocytes) as well as the collagen and proteoglycans content. Selective PDT was performed using aluminum phthalocyanine tetrasulfonate (AlPcS4), a hydrophilic compound, soluble in biological solutions, as a photosensitizer. After irradiation with a diode laser (lambda equals 670 nm, 10 mW) damage was observed in vascularized synovium grafts, whereas avascular cartilage remained intact.

  17. Recombinant Mouse Canstatin Inhibits Chicken Embryo Chorioallantoic Membrane Angiogenesis and Endothelial Cell Proliferation

    Institute of Scientific and Technical Information of China (English)

    Wei-Hong HOU; Tian-Yun WANG; Bao-Mei YUAN; Yu-Rong CHAI; Yan-Long JIA; Fang TIAN; Jian-Min WANG; Le-Xun XUE

    2004-01-01

    Human canstatin, a 24 kD fragment of the α2 chain of type Ⅳ collagen, has been proved to be one of the most effective inhibitors of angiogenesis and tumor growth. To investigate in vivo antiangiogenesis activity and in vitro effects on endothelial cell proliferation of recombinant mouse canstatin, the cDNA of mouse canstatin was introduced into an expression vector pQE40 to construct a prokaryotic expression vector pQE-mCan. The recombinant mouse canstatin efficiently expressed in E. coli M 15 after IPTG induction was monitored by SDS-PAGE and by Western blotting with an anti-hexahistidine tag antibody. The expressed mouse canstatin, mainly as inclusion bodies, accounted for approximately 35% of the total bacterial proteins. The inclusion bodies were washed, lysed and purified by the nickel affinity chromatography to a purity of approximately 93%. The refolded mouse canstatin was tested on the chicken embryo chorioallantoic membranes (CAM), and a large number of newly formed blood vessels were significantly regressed. In addition, recombinant mouse canstatin potently inhibited endothelial cell proliferation with no inhibition on non-endothelial cells. Taken together, these findings demonstrate that the recombinant mouse canstatin effectively inhibited angiogenesis of the chicken embryo in a dose-dependent manner and specially suppressed in vitro the proliferation of human umbilical vein endothelial cells.

  18. The Fractal-based Analysis of the Regulation of Vascular Remodeling in the Quail Chorioallantoic Membrane

    Science.gov (United States)

    Smith, Genee S.

    2004-01-01

    Critical to the advancement of space exploration is the safety and well being of astronauts while in space. This study focuses on the second highest of NASA-defined risk categories for human space exploration, cardiovascular alterations. Current research of this problem is being tackled by investigating angiogenesis through vascular remodeling. Angiogenesis is the growth and formation of new blood vessels. Angiogenesis is an important part of maintaining normal development and bodily functions. The loss of control of this process, either insufficient or excessive vascular growth, is considered a common denominator in many diseases, such as cancer, diabetes, and coronary artery disease. Objectives are presently being met by observing the effects of various regulators, like thrombospondin 1 (TSP-1) and a novel vessel tortuosity factor (TF), through the use of the chorioallantoic membrane (CAM) of Japanese quail embryos, which enables the direct optical imaging of 2-dimensional vascular branching trees. Research within the CAM is being performed to deduce numerous methods of regulating vessel growth. This project centers on the ability of a novel vessel regulator to affect angiogenesis. For example, it is hypothesized that the TSP-1 will inhibit the growth of CAM vasculature. Fractal/VESGEN-based techniques and PTV analysis are the methodologies used to investigate vascular differentiation. This tactic is used to quantify results and measure the growth patterns and morphology of blood vessels. The regulatory mechanisms posed by this vessel regulator can be deduced by alterations found within the vasculature patterns of quail embryos.

  19. Launch Conditions Might Affect the Formation of Blood Vessel in the Quail Chorioallantoic Membrane

    Science.gov (United States)

    Henry, M. K.; Unsworth, B. R.; Sychev, B. R.; Guryeva, T. S.; Dadasheva, O. A.; Piert, S. J.; Lagel, K. E.; Dubrovin, L. C.; Jahns, G. C.; Boda, K.; Sabo, V.; Samet, M. M.; Lelkes, P. I.

    1998-01-01

    AS 2 part of the first joint USA-Russian MIR/Shuttle program, fertilized quail eggs were flown on the MIR 18 mission. Post-flight examination indicated impaired survival of both the embryos in space and also of control embryos exposed to vibrational and g-forces simulating the conditions experienced during the launch of Progress 227. We hypothesized that excess mechanical forces and/or other conditions during the launch might cause abnormal development of the blood supply in the chorioallantoic membrane (CAM) leading to the impaired survival of the embryos. The CAM, a highly vascularized extraembryonic organ, provides for the oxygen exchange across the egg shell and is thus pivotal for proper embryonic development. To test our hypothesis, we compared angiogenesis In CAMS of eggs which were either exposed to the vibration and g-force profile simulating the conditions at launch of Progress 227 (synchronous controls), or kept under routine conditions in a laboratory Incubator (laboratory controls). At various time points during Incubation, the eggs were fixed in paraformaldehyde for subsequent dissection. At the time of dissection, the CAM was carefully lifted from the egg shell and examined as whole mounts by bright-field and fluorescent microscopy. The development or the vasculature (angiogenesis) was assessed from the density of blood vessels per viewing field and evaluated by computer aided image analysis. We observed a significant decrease In blood-vessel density in the synchronous controls versus "normal" laboratory controls beginning from day 10 of Incubation. The decrease in vascular density was restricted to the smallest vessels only, suggesting that conditions during the launch and/or during the subsequent Incubation of the eggs may affect the normal progress of angiogenesis in the CAM. Abnormal angiogenesis In the CAM might contribute to the impaired survival of the embryos observed in synchronous controls as well as in space.

  20. Assessment of angiogenic properties of biomaterials using the chicken embryo chorioallantoic membrane assay

    International Nuclear Information System (INIS)

    The angiogenic potential of a biomaterial is a critical factor for successful graft intake in tissue engineering. We developed a modified, rapid and reproducible chicken embryo chorioallantoic membrane (CAM) assay to evaluate the ability of biomaterials in inducing blood vessel density. Five biomaterials including one-layer porcine small intestinal submucosa (SIS), two-layer SIS, four-layer vacuum pressed (VP) SIS, polyglycolic acid (PGA) and PGA modified with poly(lactic-co-glycolic acid) (PLGA) were analyzed. A circular section (1.2 mm diameter) of each biomaterial was placed near a group of blood vessels in the CAM. Blood vessels around the biomaterials were captured with black and white images at 96 h post implantation; and the images were subjected to densitometry evaluation. One-layer SIS induced a significant increase in blood vessel density as compared to the cellulose nitrate negative control, and had the greatest increase in blood vessel density as compared to four-layer VP SIS, PGA, or PLGA modified PGA. Although two-layer SIS has enhanced physical structure for surgical manipulation, its induction in blood vessel density was significantly lower than the one-layer SIS. Stripping the SIS proteins or incubating one-layer SIS with neutralizing antibodies against basic fibroblast growth factor (bFGF) or vascular endothelial growth factor (VEGF) resulted in decreased angiogenesis. Consistent with results obtained from bladder augmentation animal models, these results confirmed that angiogenic growth factors were present in SIS and affected the angiogenic potential of biomaterials. These data also demonstrated that the CAM assay can be used to ascertain methodically the angiogenic potential of biomaterials

  1. Gene transfer to chicks using lentiviral vectors administered via the embryonic chorioallantoic membrane.

    Directory of Open Access Journals (Sweden)

    Gideon Hen

    Full Text Available The lack of affordable techniques for gene transfer in birds has inhibited the advancement of molecular studies in avian species. Here we demonstrate a new approach for introducing genes into chicken somatic tissues by administration of a lentiviral vector, derived from the feline immunodeficiency virus (FIV, into the chorioallantoic membrane (CAM of chick embryos on embryonic day 11. The FIV-derived vectors carried yellow fluorescent protein (YFP or recombinant alpha-melanocyte-stimulating hormone (α-MSH genes, driven by the cytomegalovirus (CMV promoter. Transgene expression, detected in chicks 2 days after hatch by quantitative real-time PCR, was mostly observed in the liver and spleen. Lower expression levels were also detected in the brain, kidney, heart and breast muscle. Immunofluorescence and flow cytometry analyses confirmed transgene expression in chick tissues at the protein level, demonstrating a transduction efficiency of ∼0.46% of liver cells. Integration of the viral vector into the chicken genome was demonstrated using genomic repetitive (CR1-PCR amplification. Viability and stability of the transduced cells was confirmed using terminal deoxynucleotidyl transferase (dUTP nick end labeling (TUNEL assay, immunostaining with anti-proliferating cell nuclear antigen (anti-PCNA, and detection of transgene expression 51 days post transduction. Our approach led to only 9% drop in hatching efficiency compared to non-injected embryos, and all of the hatched chicks expressed the transgenes. We suggest that the transduction efficiency of FIV vectors combined with the accessibility of the CAM vasculature as a delivery route comprise a new powerful and practical approach for gene delivery into somatic tissues of chickens. Most relevant is the efficient transduction of the liver, which specializes in the production and secretion of proteins, thereby providing an optimal target for prolonged study of secreted hormones and peptides.

  2. Chicken chorioallantoic membrane as a reliable model to evaluate osteosarcoma—an experimental approach using SaOS2 cell line

    OpenAIRE

    Manjunathan, Reji; Ragunathan, Malathi

    2015-01-01

    Background Osteosarcoma is the most common primary tumor that affects usually children. Due to its cellular complex and osteoid formation it is very difficult to understand the mechanism behind the progressiveness of osteosarcoma. Various animal models are available to study the issue but they are time consuming and costly. We aimed to understand the progressiveness and invasiveness of osteosarcoma induced by SaOS2 cells using chicken chorioallantoic membrane. CAM is a well-established model ...

  3. The chorioallantoic membrane (CAM) assay for the study of human bone regeneration: a refinement animal model for tissue engineering

    Science.gov (United States)

    Moreno-Jiménez, Inés; Hulsart-Billstrom, Gry; Lanham, Stuart A.; Janeczek, Agnieszka A.; Kontouli, Nasia; Kanczler, Janos M.; Evans, Nicholas D.; Oreffo, Richard Oc

    2016-08-01

    Biomaterial development for tissue engineering applications is rapidly increasing but necessitates efficacy and safety testing prior to clinical application. Current in vitro and in vivo models hold a number of limitations, including expense, lack of correlation between animal models and human outcomes and the need to perform invasive procedures on animals; hence requiring new predictive screening methods. In the present study we tested the hypothesis that the chick embryo chorioallantoic membrane (CAM) can be used as a bioreactor to culture and study the regeneration of human living bone. We extracted bone cylinders from human femoral heads, simulated an injury using a drill-hole defect, and implanted the bone on CAM or in vitro control-culture. Micro-computed tomography (μCT) was used to quantify the magnitude and location of bone volume changes followed by histological analyses to assess bone repair. CAM blood vessels were observed to infiltrate the human bone cylinder and maintain human cell viability. Histological evaluation revealed extensive extracellular matrix deposition in proximity to endochondral condensations (Sox9+) on the CAM-implanted bone cylinders, correlating with a significant increase in bone volume by μCT analysis (p human-avian system offers a simple refinement model for animal research and a step towards a humanized in vivo model for tissue engineering.

  4. The chorioallantoic membrane (CAM) assay for the study of human bone regeneration: a refinement animal model for tissue engineering

    Science.gov (United States)

    Moreno-Jiménez, Inés; Hulsart-Billstrom, Gry; Lanham, Stuart A.; Janeczek, Agnieszka A.; Kontouli, Nasia; Kanczler, Janos M.; Evans, Nicholas D.; Oreffo, Richard OC

    2016-01-01

    Biomaterial development for tissue engineering applications is rapidly increasing but necessitates efficacy and safety testing prior to clinical application. Current in vitro and in vivo models hold a number of limitations, including expense, lack of correlation between animal models and human outcomes and the need to perform invasive procedures on animals; hence requiring new predictive screening methods. In the present study we tested the hypothesis that the chick embryo chorioallantoic membrane (CAM) can be used as a bioreactor to culture and study the regeneration of human living bone. We extracted bone cylinders from human femoral heads, simulated an injury using a drill-hole defect, and implanted the bone on CAM or in vitro control-culture. Micro-computed tomography (μCT) was used to quantify the magnitude and location of bone volume changes followed by histological analyses to assess bone repair. CAM blood vessels were observed to infiltrate the human bone cylinder and maintain human cell viability. Histological evaluation revealed extensive extracellular matrix deposition in proximity to endochondral condensations (Sox9+) on the CAM-implanted bone cylinders, correlating with a significant increase in bone volume by μCT analysis (p animal research and a step towards a humanized in vivo model for tissue engineering. PMID:27577960

  5. The chorioallantoic membrane (CAM) assay for the study of human bone regeneration: a refinement animal model for tissue engineering

    Science.gov (United States)

    Moreno-Jiménez, Inés; Hulsart-Billstrom, Gry; Lanham, Stuart A.; Janeczek, Agnieszka A.; Kontouli, Nasia; Kanczler, Janos M.; Evans, Nicholas D.; Oreffo, Richard Oc

    2016-08-01

    Biomaterial development for tissue engineering applications is rapidly increasing but necessitates efficacy and safety testing prior to clinical application. Current in vitro and in vivo models hold a number of limitations, including expense, lack of correlation between animal models and human outcomes and the need to perform invasive procedures on animals; hence requiring new predictive screening methods. In the present study we tested the hypothesis that the chick embryo chorioallantoic membrane (CAM) can be used as a bioreactor to culture and study the regeneration of human living bone. We extracted bone cylinders from human femoral heads, simulated an injury using a drill-hole defect, and implanted the bone on CAM or in vitro control-culture. Micro-computed tomography (μCT) was used to quantify the magnitude and location of bone volume changes followed by histological analyses to assess bone repair. CAM blood vessels were observed to infiltrate the human bone cylinder and maintain human cell viability. Histological evaluation revealed extensive extracellular matrix deposition in proximity to endochondral condensations (Sox9+) on the CAM-implanted bone cylinders, correlating with a significant increase in bone volume by μCT analysis (p < 0.01). This human-avian system offers a simple refinement model for animal research and a step towards a humanized in vivo model for tissue engineering.

  6. Chorioallantoic Membrane Microtumor Model to Study the Mechanisms of Tumor Angiogenesis, Vascular Permeability, and Tumor Cell Intravasation.

    Science.gov (United States)

    Deryugina, Elena I

    2016-01-01

    The mechanisms governing the development of angiogenic blood vessels, which not only deliver the nutrients to growing tumors but also provide the conduits for tumor cell dissemination, are still not fully resolved. The model systems based on the grafting of human tumor cells onto the chorioallantoic membrane (CAM) of the chick embryo offer several advantages to study complex processes underlying tumor angiogenesis and tumor cell dissemination. In particular, the CAM model described here allows for investigation of multiple microtumors as independent entities, thereby greatly facilitating quantification and statistical analyses of tumor neovascularization and cancer spreading. This CAM microtumor system was designed specifically to measure the level of tumor cell intravasation in combination with quantitative analyses of the microarchitecture and permeability of the intratumoral angiogenic blood vessels. By using this newly established microtumor model we have demonstrated the functional involvement of tumor matrix metalloproteinase-1 (MMP-1) and epidermal growth factor receptor (EGFR) in regulating the development of a distinct angiogenic vasculature capable of sustaining tumor cell intravasation and metastasis. PMID:27172961

  7. The chorioallantoic membrane (CAM) assay for the study of human bone regeneration: a refinement animal model for tissue engineering.

    Science.gov (United States)

    Moreno-Jiménez, Inés; Hulsart-Billstrom, Gry; Lanham, Stuart A; Janeczek, Agnieszka A; Kontouli, Nasia; Kanczler, Janos M; Evans, Nicholas D; Oreffo, Richard Oc

    2016-01-01

    Biomaterial development for tissue engineering applications is rapidly increasing but necessitates efficacy and safety testing prior to clinical application. Current in vitro and in vivo models hold a number of limitations, including expense, lack of correlation between animal models and human outcomes and the need to perform invasive procedures on animals; hence requiring new predictive screening methods. In the present study we tested the hypothesis that the chick embryo chorioallantoic membrane (CAM) can be used as a bioreactor to culture and study the regeneration of human living bone. We extracted bone cylinders from human femoral heads, simulated an injury using a drill-hole defect, and implanted the bone on CAM or in vitro control-culture. Micro-computed tomography (μCT) was used to quantify the magnitude and location of bone volume changes followed by histological analyses to assess bone repair. CAM blood vessels were observed to infiltrate the human bone cylinder and maintain human cell viability. Histological evaluation revealed extensive extracellular matrix deposition in proximity to endochondral condensations (Sox9+) on the CAM-implanted bone cylinders, correlating with a significant increase in bone volume by μCT analysis (p animal research and a step towards a humanized in vivo model for tissue engineering. PMID:27577960

  8. Evaluation of the tissue toxicity of antiseptics by the hen's egg test on the chorioallantoic membrane (HETCAM

    Directory of Open Access Journals (Sweden)

    Marquardt C

    2010-05-01

    Full Text Available Abstract Background Antiseptics are frequently used for the prophylaxis and treatment of local infections of chronic wounds. Whereas local antiseptics in general have a positive effect on wound healing an uncritical use may impair wound healing due to toxic side effects. Objective We sought to assess the vascular irritation potential of different antiseptic solutions and ointments commonly used for short and long term application as a measure of tissue toxicity. Method The vascular irritation was evaluated by the hen's egg test (HET on the chorioallantoic membrane (CAM. The effects on the vessels of a mucous membrane were directly assessed by stereomicroscopic observation in vivo. Results Severe CAM irritation was observed after short-term applications of 1% octenidin-2HCl (Octeni sept™, 72% isopropanol (Cutasept™, 0.35% chloroxylenol (Dettol™ and 10% PVP-I ointment (Betaisodona™. Medium irritations were observed for 10% PVP-I solution (Betaisodona™, 3% lysosomal PVP-I ointment (Repithel™, 1.8% cadexomer-iodine ointment (Iodosorb™ and 1% cadexomer-iodine pellets (Iodosorb™. Finally, slight irritations were observed for 1% PVP-I solution (Betaisodona™, 0.1% polyhexanid plus betain (Prontosan™ and 1% silver-sulfadiazine ointment (Flammazine™, whereas 0.04% polyhexanid solution (Lavanid™, washings from sterile maggots of Lucilia sericata and filtrated enzymes from Clostridium histolyticum (Iruxol-N™ showed no effects of irritation. In the long-term approaches, no vascular irritations were found for polyhexanid, washings from Lucilia sericata and enzyme filtrations from Clostridium histolyticum. Conclusion The vascular injuries caused by the studied antiseptics are an indirect indicator of their tissue toxicity. Strikingly, even therapeutic substances, which have been regarded as safe in their application for the treatment of chronic wounds in clinical studies, showed severe irritations on the CAM. We suggest that agents

  9. Adaptation of infectious bronchitis virus in primary cells of the chick embryo chorioallantoic membrane

    Directory of Open Access Journals (Sweden)

    M. H. Mohammed

    2013-06-01

    Full Text Available The susceptibility of the primary chick embryo chorioallontoic membrane cells to infectious bronchitis virus was evaluated after twenty consecutive passages in chick embryo chorioallontoic membrane cells. Virus replication was monitored by cytopathic observation, indirect immunoperoxidase, and reverse transcription polymerase chain reaction (RT-PCR. At 72 hours post-infection (p.i. in third passage, the cytopathic effect was characterized by rounding up of cells, monolayer detachment, intracytoplasmic brownish colouration was readily observed by immunoperoxidase from 24 hours p.i in third passage, and at all times the extracted viral RNA from IBV-infected monolayers was demonstrated by RT-PCR. Tissue culture ineffective dose50 (TCID50 was used to measure virus titration performed on primary chick embryo chorioallontoic membrane cells and the titre in twenty passage was 108.6 TCID50/ml. The results obtained in this study suggested that the primary chick embryo chorioallontoic membrane cells can be used for adaptation infectious bronchitis virus (IBV and may be considered a step forward for the use of these cells in the future for IBV vaccine production

  10. Titanium dioxide nanoparticles induce an adaptive inflammatory response and invasion and proliferation of lung epithelial cells in chorioallantoic membrane

    International Nuclear Information System (INIS)

    Titanium dioxide nanoparticles (TiO2 NPs) studies have been performed using relatively high NPs concentration under acute exposure and limited studies have compared shape effects. We hypothesized that midterm exposure to low TiO2 NPs concentration in lung epithelial cells induces carcinogenic characteristics modulated partially by NPs shape. To test our hypothesis we synthesized NPs shaped as belts (TiO2-B) using TiO2 spheres (TiO2-SP) purchased from Sigma Aldrich Co. Then, lung epithelial A549 cells were low-exposed (10 µg/cm2) to both shapes during 7 days and internalization, cytokine release and invasive potential were determined. Results showed greater TiO2-B effect on agglomerates size, cell size and granularity than TiO2-SP. Agglomerates size in cell culture medium was 310 nm and 454 nm for TiO2-SP and TiO2-B, respectively; TiO2-SP and TiO2-B induced 23% and 70% cell size decrease, respectively, whilst TiO2-SP and TiO2-B induced 7 and 14-fold of granularity increase. NOx production was down-regulated (31%) by TiO2-SP and up-regulated (70%) by TiO2-B. Both NPs induced a transient cytokine release (IL-2, IL-6, IL-8, IL-4, IFN-γ, and TNF-α) after 4 days, but cytokines returned to basal levels in TiO2-SP exposed cells while TiO2-B induced a down-regulation after 7 days. Midterm exposure to both shapes of NPs induced capability to degrade cellular extracellular matrix components from chorioallantoic membrane and Ki-67 marker showed that TiO2-B had higher proliferative potential than TiO2-SP. We conclude that midterm exposure to low NPs concentration of NPs has an impact in the acquisition of new characteristics of exposed cells and NPs shape influences cellular outcome. - Graphical abstract: (A) Lung epithelial cells were low exposed (below 10 µg/cm2) to titanium dioxide nanoparticles (TiO2-NPs) shaped as spheres (TiO2-SP) and belts (TiO2-B) for midterm (7 continuous days) separately. (B) Then, cells from each cell culture were harvested and seeded on the top

  11. Titanium dioxide nanoparticles induce an adaptive inflammatory response and invasion and proliferation of lung epithelial cells in chorioallantoic membrane

    Energy Technology Data Exchange (ETDEWEB)

    Medina-Reyes, Estefany I.; Déciga-Alcaraz, Alejandro [Unidad de Biomedicina, Facultad de Estudios Superiores Iztacala, Universidad Nacional Autónoma de México, CP 54059 Estado de México (Mexico); Freyre-Fonseca, Verónica [Unidad de Biomedicina, Facultad de Estudios Superiores Iztacala, Universidad Nacional Autónoma de México, CP 54059 Estado de México (Mexico); Doctorado en Ciencias en Alimentos, Escuela Nacional de Ciencias Biológicas, Instituto Politécnico Nacional, CP 11340 México, DF (Mexico); Delgado-Buenrostro, Norma L. [Unidad de Biomedicina, Facultad de Estudios Superiores Iztacala, Universidad Nacional Autónoma de México, CP 54059 Estado de México (Mexico); Flores-Flores, José O. [Centro de Ciencias Aplicadas y Desarrollo Tecnológico, Universidad Nacional Autónoma de México, Circuito Exterior S/N, Ciudad Universitaria AP 70-186, CP 04510 México, DF (Mexico); Gutiérrez-López, Gustavo F. [Escuela Nacional de Ciencias Biológicas del Instituto Politécnico Nacional, CP 11340 México, DF (Mexico); Sánchez-Pérez, Yesennia; García-Cuéllar, Claudia M. [Instituto Nacional de Cancerología, Subdirección de Investigación Básica, San Fernando 22, Tlalpan, CP 14080 México, DF (Mexico); and others

    2015-01-15

    Titanium dioxide nanoparticles (TiO{sub 2} NPs) studies have been performed using relatively high NPs concentration under acute exposure and limited studies have compared shape effects. We hypothesized that midterm exposure to low TiO{sub 2} NPs concentration in lung epithelial cells induces carcinogenic characteristics modulated partially by NPs shape. To test our hypothesis we synthesized NPs shaped as belts (TiO{sub 2}-B) using TiO{sub 2} spheres (TiO{sub 2}-SP) purchased from Sigma Aldrich Co. Then, lung epithelial A549 cells were low-exposed (10 µg/cm{sup 2}) to both shapes during 7 days and internalization, cytokine release and invasive potential were determined. Results showed greater TiO{sub 2}-B effect on agglomerates size, cell size and granularity than TiO{sub 2}-SP. Agglomerates size in cell culture medium was 310 nm and 454 nm for TiO{sub 2}-SP and TiO{sub 2}-B, respectively; TiO{sub 2}-SP and TiO{sub 2}-B induced 23% and 70% cell size decrease, respectively, whilst TiO{sub 2}-SP and TiO{sub 2}-B induced 7 and 14-fold of granularity increase. NO{sub x} production was down-regulated (31%) by TiO{sub 2}-SP and up-regulated (70%) by TiO{sub 2}-B. Both NPs induced a transient cytokine release (IL-2, IL-6, IL-8, IL-4, IFN-γ, and TNF-α) after 4 days, but cytokines returned to basal levels in TiO{sub 2}-SP exposed cells while TiO{sub 2}-B induced a down-regulation after 7 days. Midterm exposure to both shapes of NPs induced capability to degrade cellular extracellular matrix components from chorioallantoic membrane and Ki-67 marker showed that TiO{sub 2}-B had higher proliferative potential than TiO{sub 2}-SP. We conclude that midterm exposure to low NPs concentration of NPs has an impact in the acquisition of new characteristics of exposed cells and NPs shape influences cellular outcome. - Graphical abstract: (A) Lung epithelial cells were low exposed (below 10 µg/cm{sup 2}) to titanium dioxide nanoparticles (TiO{sub 2}-NPs) shaped as spheres (TiO{sub 2

  12. Artesunate reduces chicken chorioallantoic membrane neovascularisation and exhibits antiangiogenic and apoptotic activity on human microvascular dermal endothelial cell.

    Science.gov (United States)

    Huan-huan, Chen; Li-Li, You; Shang-Bin, Li

    2004-08-10

    Artesunate (ART), a semi-synthetic derivative of artemisinin extracted from the Chinese herb Artemisia annua, is a safe and effective antimalarial drug. ART has now been analyzed for its anti-angiogenic activity in vivo and in vitro. The anti-angiogenic effect in vivo was evaluated on chicken chorioallantoic membrane (CAM) neovascularisation model. ART started to significantly inhibit CAM angiogenesis at a low concentration of 10 nm/100 microl/egg, and completely inhibited the angiogenesis at 80 nm/100 microl/egg. The inhibitory effect of in vitro angiogenesis was tested on the models of proliferation and differentiation of human microvascular dermal endothelial cell line, an important representive of endothelial cells, as well as immunocytochemistry assay for two major VEGF receptors (Flt-1 and KDR/flk-1) expressions. The results showed that ART could remarkably inhibit proliferation and differentiation of endothelial cells in a dose-dependent form in a range of 12.5-100 microM. ART also could reduce Flt-1 and KDR/flk-1 expressions in a range of 0.1-0.5 microM. Furthermore, we examined the apoptosis of human microvascular dermal endothelial cell line induced by ART. The apoptosis was detected by morphological assay of ethidium bromide (EB)/acridine orange (AO) dual staining as well as DNA fragmentation assay of TUNEL labeling and quantified by flowcytometric PI assay. Our results suggest that the antiangiogenic effect induced by ART might occur by the induction of cellular apoptosis. These findings and the known low toxicity indicated ART might be a promising candidate for angiogenesis inhibitors. PMID:15219940

  13. Specific tumor-stroma interactions of EBV-positive Burkitt's lymphoma cells in the chick chorioallantoic membrane

    Directory of Open Access Journals (Sweden)

    Becker Jürgen

    2012-03-01

    Full Text Available Abstract Background Burkitt's lymphoma (BL is an aggressive Non-Hodgkin lymphoma. Epstein-Barr Virus (EBV is able to transform B cells and is a causative infectious agent in BL. The precise role of EBV in lymphoma progression is still unclear. Most investigations have concentrated on cell autonomous functions of EBV in B cells. Functions of the local environment in BL progression have rarely been studied, mainly due to the lack of appropriate in vivo models. Therefore, we inoculated different human BL cell-lines onto the chorioallantoic membrane (CAM of embryonic day 10 (ED10 chick embryos and re-incubated until ED14 and ED17. Results All cell-lines formed solid tumors. However, we observed strong differences in the behavior of EBV+ and EBV- cell-lines. Tumor borders of EBV+ cells were very fuzzy and numerous cells migrated into the CAM. In EBV- tumors, the borders were much better defined. In contrast to EBV- cells, the EBV+ cells induced massive immigration of chick leukocytes at the tumor borders and the development of granulation tissue with large numbers of blood vessels and lymphatics, although the expression of pro- and anti-angiogenic forms of Vascular Endothelial Growth Factors/receptors was the same in all BL cell-lines tested. The EBV+ cell-lines massively disseminated via the lymphatics and completely occluded them. Conclusions Our data suggest that the EBV+ cells attract pro-angiogenic leukocytes, which then induce secondary tumor-stroma interactions contributing to the progression of BL. We show that the CAM is a highly suitable in vivo model to study the differential behavior of BL cell-lines.

  14. The Chick Chorioallantoic Membrane: A Model of Molecular, Structural, and Functional Adaptation to Transepithelial Ion Transport and Barrier Function during Embryonic Development

    Directory of Open Access Journals (Sweden)

    Maria Gabriella Gabrielli

    2010-01-01

    Full Text Available The chick chorioallantoic membrane is a very simple extraembryonic membrane which serves multiple functions during embryo development; it is the site of exchange of respiratory gases, calcium transport from the eggshell, acid-base homeostasis in the embryo, and ion and H2O reabsorption from the allantoic fluid. All these functions are accomplished by its epithelia, the chorionic and the allantoic epithelium, by differentiation of a wide range of structural and molecular peculiarities which make them highly specialized, ion transporting epithelia. Studying the different aspects of such a developmental strategy emphasizes the functional potential of the epithelium and offers an excellent model system to gain insights into questions partly still unresolved.

  15. Forskolin-induced differentiation of BeWo cells stimulates increased tumor growth in the chorioallantoic membrane (CAM) of the turkey (Meleagris gallopavo) egg.

    Science.gov (United States)

    Schneider, Ralf; Borges, Marcus; Kadyrov, Mamed

    2011-05-01

    Invasiveness of BeWo cells has been assessed in a variety of assay systems including matrigel and mouse. At the same time BeWo cells are mostly used as model system for trophoblast fusion. Here we aimed to test the properties of BeWo cells in a combined approach. We forced BeWo cells to differentiate by culturing the cells in the presence of forskolin and then used these cells for invasion assays on the chorioallantoic membrane (CAM) of the turkey. The chorioallantoic membranes of turkey eggs were incubated with medium containing forskolin, BeWo cells cultured in medium alone, BeWo cells cultured in forskolin and washed, and BeWo cells cultured in forskolin and used directly for application. Suspensions were applied onto ten CAM per condition. For local tumor formation eggs were checked for tumor development every 24h macroscopically for up to 12 days and immunohistochemistry for cytokeratin 18 and Ki-67 were used for further analysis. Forskolin alone did not have any deleterious effect on the CAM. When the CAM was incubated with BeWo cells cultured in medium 40% of the eggs developed a macroscopically visible tumor. BeWo cells stimulated with forskolin and washed induced tumor growth in 50% of the eggs, while forskolin stimulated BeWo cells applied directly onto the CAM induced tumor growth in 70% of the eggs. Forced differentiation of BeWo cells by forskolin may lead to syncytial fusion in a plastic culture dish. Under the conditions used here, i.e. in direct contact to a living tissue, forskolin-induced differentiation of BeWo cells leads to an increase in tumor formation in the CAM. Thus BeWo cells may use signaling pathways to decide for both differentiation pathways similar to primary trophoblast depending on the environment.

  16. Confocal observation of hydrophilic and lipophilic photosensitizers in endothelial cells, lumen of the vessels, interstitium, and tumor cells using the chicken chorioallantoic membrane

    Science.gov (United States)

    Rueck, Angelika C.; Akguen, Nermin; Heckelsmiller, K.; Beck, Gerd C.; Genze, Felicitas; Steiner, Rudolf W.

    1998-05-01

    The dynamic behavior of lipophilic and hydrophilic sensitizers in cell cultures and non animal in vivo systems with varying incubation but also during the photodynamic therapy will be summarized within the presentation. As an appropriate in vivo system we used the chorioallantoic membrane (CAM) of fertilized eggs, which served as a substrate for tumor cells. Because the CAM is a transparent membrane it is possible to view individual blood vessels and to examine tumor cells as well as structural changes of the supplying vasculature. To adapt this system to high magnification microscopy, we established a new technique for in vivo observation of the CAM tissue. This technique enables online investigations of alterations at cellular level induced by drugs with confocal laser scanning microscopy. The localization of the drugs with clinical importance was observed after different application times in the lumen of the vessels, the endothelial cells and the tumor cells. In addition light induced subcellular Ca2+-changes were observed and correlated with the photodynamic process.

  17. Synthesis and characterization of MFe2O4 (M = Co, Ni, Mn) magnetic nanoparticles for modulation of angiogenesis in chick chorioallantoic membrane (CAM).

    Science.gov (United States)

    Nooris, Momin; Aparna, Deshmukh; Radha, S

    2016-03-01

    In this study, we report the synthesis and characterization studies of amine-functionalized MFe2O4 (Co, Ni, Mn) nanoparticles. The synthesis process was accomplished by refluxing metal chloride precursors in ethylene glycol in the presence of sodium acetate and ethanolamine. The average crystallite sizes of the synthesized particles are found to be in the range of 8-10 nm. The synthesized particles are characterized using X-ray diffraction, Brunauer-Emmett-Teller technique, FTIR, dynamic light scattering, Raman and UV-visible spectroscopy for crystal structure, average size, surface area, pore diameter and hydrodynamic diameter, phase and functional group determination. The surface morphology and elemental composition were studied by scanning electron microscope and X-ray fluorescence respectively. Magnetic behavior up to fields of 3 T at room temperature measured in Quantum Design Physical Property Measurement System (QD PPMS) magnetometer showed the superparamagnetic behavior of these particles. Modulation of angiogenesis by the nanoparticles was studied in a chick embryo chorioallantoic membrane model by analysis of blood vessel development and effect on hemoglobin level using imaging and colorimetric methods. An enhancement in the angiogenesis compared to the saline control was observed for all the ferrite nanoparticles with a relatively optimal activity in case of CoFe2O4 nanoparticles. PMID:26493065

  18. Optical properties of tumor tissues grown on the chorioallantoic membrane of chicken eggs: tumor model to assay of tumor response to photodynamic therapy

    Science.gov (United States)

    Honda, Norihiro; Kariyama, Yoichiro; Hazama, Hisanao; Ishii, Takuya; Kitajima, Yuya; Inoue, Katsushi; Ishizuka, Masahiro; Tanaka, Tohru; Awazu, Kunio

    2015-12-01

    Herein, the optical adequacy of a tumor model prepared with tumor cells grown on the chorioallantoic membrane (CAM) of a chicken egg is evaluated as an alternative to the mouse tumor model to assess the optimal irradiation conditions in photodynamic therapy (PDT). The optical properties of CAM and mouse tumor tissues were measured with a double integrating sphere and the inverse Monte Carlo technique in the 350- to 1000-nm wavelength range. The hemoglobin and water absorption bands observed in the CAM tumor tissue (10 eggs and 10 tumors) are equal to that of the mouse tumor tissue (8 animals and 8 tumors). The optical intersubject variability of the CAM tumor tissues meets or exceeds that of the mouse tumor tissues, and the reduced scattering coefficient spectra of CAM tumor tissues can be equated with those of mouse tumor tissues. These results confirm that the CAM tumor model is a viable alternative to the mouse tumor model, especially for deriving optimal irradiation conditions in PDT.

  19. Investigating the Synergic Effects of Ethanolic Extract of Allium sativum L and Electromagnetic Field with Low Frequency on Angiogenesis in Chick Chorioallantoic Membrane (In Vivo

    Directory of Open Access Journals (Sweden)

    D Sadooghi

    2013-10-01

    Full Text Available Introduction: A number of researches show anti-proliferative effects of EMF on animal cells. In addition to antioxidant properties of garlic,it contains compounds that can inhibit cell proliferation. This study wasconducted to investigate the effects of garlic extract and EMF with low frequency on angiogenesis. Methods: Eighty fertilized eggs were divided into the control group, sham-exposed 1 (treated by normal saline, sham-exposed 2 (in vicinity of switched off EMF, experimental group 1 (treated by concentration 100 μg/ml of garlic extract, experimental group 2 (treated by concentration 200 μg/ml of garlic extract, experimental group 3 (in vicinity of EMF with intensity of 50 gauss, experimental group 4 (treated by concentration 100 μg/ml of garlic extract and EMF with intensity of 50 gauss, experimental group 5 (treated by concentration 200 μg/ml of garlic extract and EMF with intensity of 50 gauss. On the 8th day of incubation, gelatin sponge was placed on the chorioallantoic membrane and experimental groups 1, 2, 4, and 5 were treated with 10 microliters of garlic extract. On the 10th day of incubation, experimental groups 3, 4 and 5 were exposed to EMF for 4 hours. All samples were photographed on the 12th day of incubation and the length and numbers of vessels were analyzed by ANOVA and Tukey statistical tests. Results: The mean number and length of blood vessels in all experimental groups were significantly decreased compared to the control group (p<0.05. Conclusion: Garlic has inhibitory effects on angiogenesis. Moreover, these effects wereamplified by EMF with intensity of 50 gauss.

  20. Co-culture of adipose-derived stem cells and endothelial cells in fibrin induces angiogenesis and vasculogenesis in a chorioallantoic membrane model.

    Science.gov (United States)

    Strassburg, Sandra; Nienhueser, Henrik; Björn Stark, G; Finkenzeller, Günter; Torio-Padron, Nestor

    2016-06-01

    Neovascularization of adipose tissue equivalents is a crucial step in successful adipose tissue engineering, since insufficient vascularization results in graft resorption in an in vivo situation. A possible cellular approach to overcome this limitation is the co-implantation of adipose-derived stem cells (ASCs) with endothelial cells to stimulate the formation of a vascular network. We investigated the potential of ASCs derived from human abdominal fat tissue co-cultured with endothelial progenitor cells (EPCs) from human peripheral blood to stimulate neovascularization of fibrin constructs on the chorioallantoic membrane (CAM) of fertilized chicken eggs, in direct comparison to human umbilical vein endothelial cells (HUVECs). After 9 days of incubation, cell-fibrin constructs were explanted and histologically evaluated with respect to ingrowth of avian blood vessels into the construct and formation of human blood vessels by co-implanted endothelial cells. When administered on the CAM, ASCs successfully guided host vasculature into the construct (angiogenesis) and guided formation of capillary-like structures by co-implanted human endothelial cells (vasculogenesis), with HUVECs being superior to EPCs, leading to a perfused avian and human capillary network within the fibrin construct. However, the results also showed that perfused human blood vessels were only observed near the CAM compared to unperfused capillary-like structures near the top of the construct, indicating that perfusion of the cell-fibrin construct takes longer than 9 days. In conclusion, as blood vessel formation is an essential step during adipogenic differentiation, the data support our hypothesis that cellular communication between transplanted ASCs and endothelial cells is beneficial for vasculogenesis. Copyright © 2013 John Wiley & Sons, Ltd. PMID:23712963

  1. Early Transcriptional Responses of Bovine Chorioallantoic Membrane Explants to Wild Type, ΔvirB2 or ΔbtpB Brucella abortus Infection

    Science.gov (United States)

    Mol, Juliana P. S.; Costa, Erica A.; Carvalho, Alex F.; Sun, Yao-Hui; Tsolis, Reneé M.; Paixão, Tatiane A.; Santos, Renato L.

    2014-01-01

    The pathogenesis of the Brucella-induced inflammatory response in the bovine placenta is not completely understood. In this study we evaluated the role of the B. abortus Type IV secretion system and the anti-inflammatory factor BtpB in early interactions with bovine placental tissues. Transcription profiles of chorioallantoic membrane (CAM) explants inoculated with wild type (strain 2308), ΔvirB2 or ΔbtpB Brucella abortus were compared by microarray analysis at 4 hours post infection. Transcripts with significant variation (>2 fold change; P<0.05) were functionally classified, and transcripts related to defense and inflammation were assessed by quantitative real time RT-PCR. Infection with wild type B. abortus resulted in slightly more genes with decreased than increased transcription levels. Conversely, infection of trophoblastic cells with the ΔvirB2 or the ΔbtpB mutant strains, that lack a functional T4SS or that has impaired inhibition of TLR signaling, respectively, induced more upregulated than downregulated genes. Wild type Brucella abortus impaired transcription of host genes related to immune response when compared to ΔvirB and ΔbtpB mutants. Our findings suggest that proinflammatory genes are negatively modulated in bovine trophoblastic cells at early stages of infection. The virB operon and btpB are directly or indirectly related to modulation of these host genes. These results shed light on the early interactions between B. abortus and placental tissue that ultimately culminate in inflammatory pathology and abortion. PMID:25259715

  2. Early transcriptional responses of bovine chorioallantoic membrane explants to wild type, ΔvirB2 or ΔbtpB Brucella abortus infection.

    Directory of Open Access Journals (Sweden)

    Juliana P S Mol

    Full Text Available The pathogenesis of the Brucella-induced inflammatory response in the bovine placenta is not completely understood. In this study we evaluated the role of the B. abortus Type IV secretion system and the anti-inflammatory factor BtpB in early interactions with bovine placental tissues. Transcription profiles of chorioallantoic membrane (CAM explants inoculated with wild type (strain 2308, ΔvirB2 or ΔbtpB Brucella abortus were compared by microarray analysis at 4 hours post infection. Transcripts with significant variation (>2 fold change; P<0.05 were functionally classified, and transcripts related to defense and inflammation were assessed by quantitative real time RT-PCR. Infection with wild type B. abortus resulted in slightly more genes with decreased than increased transcription levels. Conversely, infection of trophoblastic cells with the ΔvirB2 or the ΔbtpB mutant strains, that lack a functional T4SS or that has impaired inhibition of TLR signaling, respectively, induced more upregulated than downregulated genes. Wild type Brucella abortus impaired transcription of host genes related to immune response when compared to ΔvirB and ΔbtpB mutants. Our findings suggest that proinflammatory genes are negatively modulated in bovine trophoblastic cells at early stages of infection. The virB operon and btpB are directly or indirectly related to modulation of these host genes. These results shed light on the early interactions between B. abortus and placental tissue that ultimately culminate in inflammatory pathology and abortion.

  3. Survey of ocular irritation predictive capacity using Chorioallantoic Membrane Vascular Assay (CAMVA) and Bovine Corneal Opacity and Permeability (BCOP) test historical data for 319 personal care products over fourteen years.

    Science.gov (United States)

    Donahue, D A; Kaufman, L E; Avalos, J; Simion, F A; Cerven, D R

    2011-03-01

    The Chorioallantoic Membrane Vascular Assay (CAMVA) and Bovine Corneal Opacity and Permeability (BCOP) test are widely used to predict ocular irritation potential for consumer-use products. These in vitro assays do not require live animals, produce reliable predictive data for defined applicability domains compared to the Draize rabbit eye test, and are rapid and inexpensive. Data from 304 CAMVA and/or BCOP studies (319 formulations) were surveyed to determine the feasibility of predicting ocular irritation potential for various formulations. Hair shampoos, skin cleansers, and ethanol-based hair styling sprays were repeatedly predicted to be ocular irritants (accuracy rate=0.90-1.00), with skin cleanser and hair shampoo irritation largely dependent on surfactant species and concentration. Conversely, skin lotions/moisturizers and hair styling gels/lotions were repeatedly predicted to be non-irritants (accuracy rate=0.92 and 0.82, respectively). For hair shampoos, ethanol-based hair stylers, skin cleansers, and skin lotions/moisturizers, future ocular irritation testing (i.e., CAMVA/BCOP) can be nearly eliminated if new formulations are systematically compared to those previously tested using a defined decision tree. For other tested product categories, new formulations should continue to be evaluated in CAMVA/BCOP for ocular irritation potential because either the historical data exhibit significant variability (hair conditioners and mousses) or the historical sample size is too small to permit definitive conclusions (deodorants, make-up removers, massage oils, facial masks, body sprays, and other hair styling products). All decision tree conclusions should be made within a conservative weight-of-evidence context, considering the reported limitations of the BCOP test for alcohols, ketones, and solids.

  4. Construction and application of a new model of chicken chorioallantoic membrane%一种新的鸡胚尿囊膜模型的建立与应用

    Institute of Scientific and Technical Information of China (English)

    张彦民; 王红英

    2011-01-01

    Objective To construct a new model of chicken chorioallantoic membrane (CAM) and investigate the inhibition of hydrocortisone on CAM angiogenesis. Methods The CAM was constructed by air chamber. The carriers of silastic ring, methylcellulose, gelatin sponge and fiberglass filter paper were used. Results The new CAM model was ideal for anti-angiogenesis drug screening. The carrier of silastic ring had the property of direct-viewing, accurate application of sample, and convenient observation. Hydrocortisone had a good inhibitory effect on angiogenesis of CAM in the dose-effect manner. Conclusion The new CAM model is a tool for angiogenesis research. Hydrocortisone has an obvious inhibitory effect on angiogenesis of CAM by CAM model.%目的 建立一种新的鸡胚尿囊膜模型并考察氢化可的松对鸡胚尿囊膜血管生成的影响.方法 运用假气室法建立鸡胚尿囊膜模型,采用硅胶环、甲基纤维素、明胶海绵、玻璃纤维滤纸为给药载体进行考察.结果 用硅胶环作为载体建立的鸡胚尿囊膜实验模型,是一种较理想的研究抗血管生成药物的筛选模型.硅胶环作为载体与明胶海绵和纤维滤纸载体等相比,具有效果直观,加样量准确,在显微镜下易于观察、照相的优点.氢化可的松对鸡胚尿囊膜新生血管生成具有较好的抑制作用,呈现出较好的量效关系.结论 本研究建立了一种新的鸡胚尿囊膜模型,运用该模型得出氢化可的松对鸡胚尿囊膜血管生成有明显的抑制作用.

  5. Angiostatic Effects on Chick Chorioallantoic Membrane by Recombinant N-Fragment of Mouse Canstatin%重组小鼠canstatin N端片段对鸡胚新生血管生成的抑制作用

    Institute of Scientific and Technical Information of China (English)

    侯卫红; 贾岩龙; 王天云; 柴玉荣; 袁保梅; 田芳; 王建民; 薛乐勋

    2004-01-01

    为了研究重组小鼠canstatin N端片段的体内抗血管生成活性,通过PCR扩增小鼠canstatin N端片段cDNA,定向克隆于原核表达载体pET30a(+)中,构建小鼠canstatin N端片段重组表达载体pET-mCanN,转化E.coli BL21(DE3),IPTG诱导表达,SDS-聚丙烯酰胺凝胶电泳(SDS-PAGE)和蛋白质印迹检测小鼠canstatin N端片段的表达.结果表明,IPTG诱导原核表达载体pET-mCanN在大肠杆菌E.coli BL21(DE3)中高效表达,小鼠canstatin N端片段表达量约占菌体总蛋白量的18%,小鼠canstatin N端片段主要以包涵体形式存在,包涵体经过洗涤、裂解、Ni~spin column亲合柱层析以及蛋白质复性等步骤纯化后,获得了纯度约为92%的重组小鼠canstatin N端片段.鸡胚绒毛尿囊膜(chicken embryo choriollantoic membrane,CAM)实验表明,原核表达的小鼠canstafin N端片段能有效地按剂量依赖的方式抑制鸡胚新生血管的形成.%Mouse canstatin is a C-terminal globular non-collagenous domain of type 1V collagen α2 chain, which previously showed anti-angiogenic activity. To investigate in vivo angiostatic effects on chick chorioallantoic membrane (CAM) by recombinant mouse canstatin N-fragment( 1 ~95aa), the cDNA for N-fragment of mouse canstatin, obtained from a cloning vector pMD18T-mCan by PCR, was introduced into an expression vector pET30a( + ) to construct prokaryotic expression vector pET-mCanN. N-fragment of mouse canstatin efficiently expressed in E. coli BL21 (DE3) after IPTG induction was monitored by SDS-PAGE and by Western blotting with an anti-hexahistidine tag antibody. The expressed N-fragment of mouse canstatin, mainly as inclusion bodies, accounted for approximately 18% of the total bacterial proteins as estimated by densitometry. The inclusion bodies were washed, lysed and purified by the nickel affinity chromatography to a purity of 92%. The refolded N-fragment of mouse canstatin was tested on the chicken embryo CAMs, and a large number of

  6. Effects of arctigenin on angiogenesis of chick embryo chorioallantoic membrane%牛蒡子苷元对鸡胚绒毛尿囊膜血管新生的影响

    Institute of Scientific and Technical Information of China (English)

    刘奋; 薛芳喜; 关永霞; 姚景春; 闫莹

    2014-01-01

    目的:观察牛蒡子苷元对鸡胚绒毛尿囊膜( CAM)血管新生的影响。方法采用乙醇结晶法制备牛蒡子苷元,开窗法制备CAM模型。将CAM模型中的40只鸡胚随机分为阴性对照组、低剂量组、中剂量组、高剂量组,每组各10只。分别将含有DMSO、2.5、5.0、10.0 g/L牛蒡子苷元的药物载体置于阴性对照组、低剂量组、中剂量组、高剂量组CAM中央血管稀少区,孵育48 h后,剪下CAM,在解剖显微镜下观察药物载体覆盖区及CAM周围的新生血管数量、形态,观察各组新生血管等级,记录各组药物载体边缘5 mm内新生血管的数目,计算血管抑制率( IR)。结果低、中、高剂量组CAM新生血管发育均受抑制。中、高剂量组新生血管等级3+、4+的数量多于阴性对照组(P<0.05),阴性对照组、低剂量组、中剂量组、高剂量组新生血管数目分别为(78.26±5.62)、(59.22±4.16)、(37.43±6.51)、(24.17±3.23)条,低剂量组新生血管数低于阴性对照组(P<0.05),中、高剂量组新生血管数均低于阴性对照组(P<0.01),且中、高剂量组新生血管数均低于低剂量组(P<0.05)。低剂量组、中剂量组、高剂量组新生血管IR分别为24.33%、52.17%及69.12%。结论牛蒡子苷元具有抑制鸡胚CAM血管新生的作用。%Objective To observe the influence of arctigenin on the angiogenesis of chick embryo chorioallantoic membrane ( CAM) .Methods Arctigenin was prepared by the procedure of ethanol crystallization from Fructus Arctii and we used the windowing method to prepare the CAM model .Forty chick embryos of CAM models were randomly divided into the negative control group, low (2.5 g/L), medium (5.0 g/L), and high (10.0 g/L) doses of arctigenin groups, 10 em-bryos in each group .Then the negative control solution containing DMSO and each dose of liquid containing

  7. Angiogenic efficacy of Heparin on chick chorioallantoic membrane

    Directory of Open Access Journals (Sweden)

    Rema Reji

    2012-04-01

    Full Text Available Abstract Heparin is an anticoagulant agent known to have diverse effects on angiogenesis with some reports suggesting that it can induce angiogenesis while a few have indicated of its inhibitory property. Cancer patients treated for venous thromboembolism with low molecular heparin had a better survival than the unfractionated heparin (UFH. Heparin is known to interact with various angiogenic growth factors based on its sulfation modifications within the glycosaminoglycan chains. Therefore it is important to study the mechanism of action of heparin of different molecular weight to understand its angiogenic property. In this concern, we examined the angiogenic response of higher molecular weight Heparin (15 kDa of different concentrations using late CAM assay. Growth of blood vessels in terms of their length and size was measured and thickness of the CAM was calculated morphometrically. The observed increase in the thickness of the CAM is suggestive of the formation of capillary like structures at the treated region. Analysis of the diffusion pattern showed internalized action of heparin that could affect gene expression leading to proliferation of endothelial cells. Angiogenesis refers to formation of new blood vessels from the existing ones and occurrence of new blood vessels at the treated area strongly confirms that heparin of 15 kDa molecular weight has the ability to induce angiogenesis on CAM vascular bed in a dose dependent manner. The results demonstrate the affinity of heparin to induce angiogenesis and provide a novel mechanism by which heparin could be used in therapeutics such as in wound healing process.

  8. 不同鼻咽癌细胞株对鸡胚尿囊膜模型血管生成影响的比较研究%Angiogenic effect of different nasopharyngeal carcinoma cell lines on the chick embryo chorioallantoic membrane

    Institute of Scientific and Technical Information of China (English)

    林少雄; 李湘平; 鲁娟; 梁碧君; 刘雄

    2012-01-01

    Objective The purpose of this study was to compare the angiogenic effect of different nasopharyngeal carcinoma (NPC) cell lines on the chick embryo chorioallantoic membrane (CAM). Methods Six days old fertilized eggs were used in this study. A square window on the shell was cut, and the the NPC cell lines 5-8F, 6-10B and CNE-2 were inocluated into the CAM (n=10) with PBS as blank control. The eggs were then incubated for 6 days before the enumeration of the vessels number (VN). The ratios between the area covered by the vessel and the CAM (VA/ CAM) were analyzed. Results All the 3 NPC cell lines grow on the CAMs (100%) with a cell number of 2×l06/CAM. The VN was significantly decreased (P<0.05). The VA/CAM of 5-8F was significantly higher than the other two cell lines (P<0.05). The VA/CAM from the three NPC cell lines inoculated embryos were significantly higher than the control (P<0.05). Conclusion The results indicated that the angiogenic effects of these NPC cell line are different with each other, therefore the selection of these NPC cell lines may depend on the different CAM experimental conditions.%目的 比较不同鼻咽癌细胞株在鸡胚尿囊膜模型上促进血管生成能力的差异.方法 选用6日龄鸡胚,开窗后分别种植5-8F、6-10B及CNE-2三种鼻咽癌细胞株,三种细胞株细胞数为2×106/鸡胚者各一组,细胞数为5×105/鸡胚者各一组,另一组为对照组(PBS),每组10个鸡胚.孵育6日后,统计分析新生血管数及血管面积/鸡胚面积比.结果 种植细胞数为5×105/鸡胚时,5-8F、6-10B细胞部分鸡胚有移植瘤形成,CNE-2细胞鸡胚均未见成瘤.种植细胞数为2× 106/鸡胚时,三种鼻咽癌细胞株均可100%成瘤,其新生血管数依次递减,分别为(38.7±2.50)、(33.5±4.43)、(29.7±2.71),差异有统计学意义(P<0.05);血管面积/鸡胚面积比分别为(22.2±2.18)%、(18.7±2.45)%、(16.9±2.62)%,均高于对照组的(9.5±1.86)

  9. Feasibility Study of Ex Ovo Chick Chorioallantoic Artery Model for Investigating Pulsatile Variation of Arterial Geometry.

    Directory of Open Access Journals (Sweden)

    Kweon-Ho Nam

    Full Text Available Despite considerable research efforts on the relationship between arterial geometry and cardiovascular pathology, information is lacking on the pulsatile geometrical variation caused by arterial distensibility and cardiomotility because of the lack of suitable in vivo experimental models and the methodological difficulties in examining the arterial dynamics. We aimed to investigate the feasibility of using a chick embryo system as an experimental model for basic research on the pulsatile variation of arterial geometry. Optical microscope video images of various arterial shapes in chick chorioallantoic circulation were recorded from different locations and different embryo samples. The high optical transparency of the chorioallantoic membrane (CAM allowed clear observation of tiny vessels and their movements. Systolic and diastolic changes in arterial geometry were visualized by detecting the wall boundaries from binary images. Several to hundreds of microns of wall displacement variations were recognized during a pulsatile cycle. The spatial maps of the wall motion harmonics and magnitude ratio of harmonic components were obtained by analyzing the temporal brightness variation at each pixel in sequential grayscale images using spectral analysis techniques. The local variations in the spectral characteristics of the arterial wall motion were reflected well in the analysis results. In addition, mapping the phase angle of the fundamental frequency identified the regional variations in the wall motion directivity and phase shift. Regional variations in wall motion phase angle and fundamental-to-second harmonic ratio were remarkable near the bifurcation area. In summary, wall motion in various arterial geometry including straight, curved and bifurcated shapes was well observed in the CAM artery model, and their local and cyclic variations could be characterized by Fourier and wavelet transforms of the acquired video images. The CAM artery model with

  10. Angiogenic Potential of Human Neonatal Foreskin Stromal Cells in the Chick Embryo Chorioallantoic Membrane Model

    OpenAIRE

    Radhakrishnan Vishnubalaji; Muhammad Atteya; May Al-Nbaheen; Richard O. C. Oreffo; Abdullah Aldahmash; Alajez, Nehad M.

    2015-01-01

    Several studies have demonstrated the multipotentiality of human neonatal foreskin stromal cells (hNSSCs) as being able to differentiate into adipocytes and osteoblasts and potentially other cell types. Recently, we demonstrated that hNSSCs play a role during in vitro angiogenesis and appear to possess a capacity to differentiate into endothelial-like cells; however, their angiogenic potential within an ex vivo environment remains unclear. Current study shows hNSSCs to display significant mig...

  11. Angiogenic Potential of Human Neonatal Foreskin Stromal Cells in the Chick Embryo Chorioallantoic Membrane Model

    Directory of Open Access Journals (Sweden)

    Radhakrishnan Vishnubalaji

    2015-01-01

    Full Text Available Several studies have demonstrated the multipotentiality of human neonatal foreskin stromal cells (hNSSCs as being able to differentiate into adipocytes and osteoblasts and potentially other cell types. Recently, we demonstrated that hNSSCs play a role during in vitro angiogenesis and appear to possess a capacity to differentiate into endothelial-like cells; however, their angiogenic potential within an ex vivo environment remains unclear. Current study shows hNSSCs to display significant migration potential in the undifferentiated state and high responsiveness in the in vitro wound healing scratch assay. When hNSSCs were seeded onto the top of the CAM, human von Willebrand factor (hVWF, CD31, smooth muscle actin (SMA, and factor XIIIa positive cells were observed in the chick endothelium. CAMs transplanted with endothelial-differentiated hNSSCs displayed a higher number of blood vessels containing hNSSCs compared to CAMs transplanted with undifferentiated hNSSCs. Interestingly, undifferentiated hNSSCs showed a propensity to differentiate towards ectoderm with indication of epidermal formation with cells positive for CD1a, CK5/6, CK19, FXIIIa, and S-100 cells, which warrant further investigation. Our findings imply a potential angiogenic role for hNSSCs ex vivo in the differentiated and undifferentiated state, with potential contribution to blood vessel formation and potential application in tissue regeneration and vascularization.

  12. 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...

  13. A novel technique for quantifying changes in vascular density, endothelial cell proliferation and protein expression in response to modulators of angiogenesis using the chick chorioallantoic membrane (CAM assay

    Directory of Open Access Journals (Sweden)

    Kohn Elise

    2004-01-01

    Full Text Available Abstract Reliable quantitative evaluation of molecular pathways is critical for both drug discovery and treatment monitoring. We have modified the CAM assay to quantitatively measure vascular density, endothelial proliferation, and changes in protein expression in response to anti-angiogenic and pro-angiogenic agents. This improved CAM assay can correlate changes in vascular density with changes seen on a molecular level. We expect that these described modifications will result in a single in vivo assay system, which will improve the ability to investigate molecular mechanisms underlying the angiogenic response.

  14. 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...

  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. Radiosensitivity of angiogenic and mitogenic factors in human amniotic membrane

    International Nuclear Information System (INIS)

    Amniotic membrane as a temporary biological dressing remains as a beneficial and cost-effective means of treating burns in developing countries. This medical application is attributed mainly to placental structural and biochemical features that are important for maintaining proper embryonic development. Since fresh amnions are nevertheless for straightforward clinical use and for preservation, radiation-sterilization is been performed to improve the safety of this placental material. However, like any other sterilization method, gamma-radiation may induce physical and chemical changes that may influence the biological property of the material. Thus, the aim of this study is to compare the effects of various levels of radiation-sterilization protocols for human amnions on angiogenic (neovascularization) and epithelial-mitogenic activities, both of which are physiological processes fundamental to wound healing. Water-soluble extract of non-irradiated amnions demonstrates a strong stimulatory effect on both cell proliferation and angiogenesis. No change in biological activity is seen in amnions irradiated at 25 kGy, the sterilization dose used by the Philippine Nuclear Research Institute (PNRI) for the production of radiation-sterilized human amniotic membranes (RSHAM). However, it appears that amniotic angiogenic factors are more radiosensitive than its mitogenic components, evident from the depressed vascularization of the chorioallantoic membrane (CAM) exposed to 35 kGy-irradiated amnions. The dose of 35 kGy is at present the medical sterilization dose used at the Central Tissue Bank in Warsaw (Poland) for the preparation of their amnion allografts. (Authors)

  17. Endocrine activity of extraembryonic membranes extends beyond placental amniotes.

    Directory of Open Access Journals (Sweden)

    Lori C Albergotti

    Full Text Available BACKGROUND: During development, all amniotes (mammals, reptiles, and birds form extraembryonic membranes, which regulate gas and water exchange, remove metabolic wastes, provide shock absorption, and transfer maternally derived nutrients. In viviparous (live-bearing amniotes, both extraembryonic membranes and maternal uterine tissues contribute to the placenta, an endocrine organ that synthesizes, transports, and metabolizes hormones essential for development. Historically, endocrine properties of the placenta have been viewed as an innovation of placental amniotes. However, an endocrine role of extraembryonic membranes has not been investigated in oviparous (egg-laying amniotes despite similarities in their basic structure, function, and shared evolutionary ancestry. In this study, we ask whether the oviparous chorioallantoic membrane (CAM of chicken (Gallus gallus has the capability to synthesize and receive signaling of progesterone, a major placental steroid hormone. METHODOLOGY/PRINCIPAL FINDINGS: We quantified mRNA expression of key steroidogenic enzymes involved in progesterone synthesis and found that 3beta-hydroxysteroid dehydrogenase, which converts pregnenolone to progesterone exhibited a 464 fold increase in the CAM from day 8 to day 18 of embryonic development (F(5, 68 = 89.282, p<0.0001. To further investigate progesterone synthesis, we performed explant culture and found that the CAM synthesizes progesterone in vitro in the presence of a steroid precursor. Finally, we quantified mRNA expression and performed protein immunolocalization of the progesterone receptor in the CAM. CONCLUSIONS/SIGNIFICANCE: Collectively, our data indicate that the chick CAM is steroidogenic and has the capability to both synthesize progesterone and receive progesterone signaling. These findings represent a paradigm shift in evolutionary reproductive biology by suggesting that endocrine activity of extraembryonic membranes is not a novel characteristic of

  18. Membrane Biophysics

    CERN Document Server

    Ashrafuzzaman, Mohammad

    2013-01-01

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

  19. A proposed protocol for the standardized preparation of PRF membranes for clinical use.

    Science.gov (United States)

    Kobayashi, Mito; Kawase, Tomoyuki; Horimizu, Makoto; Okuda, Kazuhiro; Wolff, Larry F; Yoshie, Hiromasa

    2012-09-01

    Upon clinical application, thick platelet-rich fibrin (PRF) is usually compressed to fit the implantation site. However, it is speculated that the preservation of platelets and plasma content depends on the compression methods used. To accurately evaluate the clinical outcome of PRF, the preparation protocol should be standardized. Freshly prepared PRF clots were compressed into a thin membrane by our novel PRF compression device. The localization of platelets was examined by SEM and immunostaining. Growth factor levels were evaluated by bioassays and cytokine-antibody array techniques. The angiogenic activity was examined by the chick chorioallantoic membrane assay and the scratch assay using HUVEC cultures. Platelets were concentrated on the surface of the region adjacent to the red thrombus and this region was subjected to the experiments. Compared to the PRF membrane compressed by dry gauze (G-PRF), the preservation of the plasma content, 3D-fibrin meshwork, and platelets was more intact in the compressor-prepared PRF membrane (C-PRF). Among the growth factors tested, C-PRF contained PDGF isoforms at higher levels, and significantly stimulated cell proliferation and neovascularization. C-PRF may be useful for grafting while minimizing the loss of bioactive factors. This C-PRF preparation protocol is proposed as a standardized protocol for PRF membrane preparation.

  20. 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

  1. 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

  2. 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.

  3. Effect of Huang TFA on Angiogenesis of Chick Embryo Chorioallantoic Membrane.%黄蜀葵花总黄酮对鸡胚绒毛尿囊膜血管生成的影响

    Institute of Scientific and Technical Information of China (English)

    潘武; 蒋萌

    2010-01-01

    目的:观察黄蜀葵花总黄酮(TFA)对鸡胚绒毛尿囊膜(CAM)血管新生的影响.方法:应用鸡胚绒毛尿囊膜模型,明胶海绵为载体,观察不同浓度TFA对CAM血管新生的影响.结果:血管以栽体为中心向四周呈放射状生长,与生理盐水对照组比较,5-20μg/ml TFA组血管网明显增多、增粗,血管计数显示血管数显著增多.结论:TFA能促进鸡胚绒毛尿囊膜血管生成,提示其在体内有促血管新生作用.

  4. 益气养阴方对鸡胚绒毛尿囊膜(CAM)血管生成的影响%Effect of Yiqi Yangyin Recipe on Angiogenesis in Chicken Chorioallantoic Membrane

    Institute of Scientific and Technical Information of China (English)

    孙静

    2008-01-01

    目的:评价益气养阴方鸡胚绒毛尿囊膜血管生成的影响.方法:制备CAM模型,比较大鼠含药血清和无药血清对鸡胚绒毛尿囊膜血管生成的影响情况.结果:含药血清对鸡胚绒毛尿囊膜的血管生成产生明显抑制作用.结论:益气养阴方对活体血管的生成具有抑制作用,在肿瘤和其他病理情况下的血管形成治疗中具有一定的应用价值.

  5. 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...

  6. 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.

  7. 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.

  8. 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.

  9. 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...

  10. 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

  11. 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.

  12. 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)

  13. 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.

  14. Compositional asynchronous membrane systems

    Institute of Scientific and Technical Information of China (English)

    Cosmin Bonchis; Cornel Izbasa; Gabriel Ciobanu

    2007-01-01

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

  15. 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.

  16. Polychlorinated biphenyls in eggs and chlorioallantoic membranes of American alligators (Alligator mississippiensis) from coastal South Carolina

    Energy Technology Data Exchange (ETDEWEB)

    Cobb, G.P.; Wood, P.D. [Clemson Univ., Pendleton, SC (United States); O`Quinn, M. [South Carolina Governor`s School for Science and Mathematics, Hartsville, SC (United States)

    1997-07-01

    Assessing chemical exposure in threatened or endangered wildlife species presents unique analytical problems. Chorioallantoic membranes (CAMs) have been proposed as surrogate tissues for evaluation of polychlorinated biphenyl (PCB) exposure in oviparous species. Research was undertaken to determine the extent of PCB accumulation in alligators (Alligator mississippiensis) at sites along the coast of South Carolina and to evaluate the utility of CAMs as surrogate tissues for determining PCB concentrations in whole alligator eggs. Polychlorinated biphenyls were found in eggs and CAMs of alligators from both sites examined. Concentrations of PCBs were higher in CAMs (p = 0.02) and eggs (p = 0.001) from sites known to contain chlorinated hydrocarbons than from more pristine sites. Total PCBs partitioned predictably (r{sup 2} > 0.59; p < 0.02) between egg and CAM tissues indicating the utility of CAMs to serve as surrogate tissues when comparing total PCB concentrations in whole eggs. Tetrachloro through octachloro biphenyl homologues and total PCBs in CAMs from reference areas were correlated with concentrations of these homologues in eggs. At contaminated sites, total PCB concentrations in CAMs were correlated with total PCB concentrations in eggs.

  17. 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.

  18. 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.

  19. Membrane Automata with Priorities

    Institute of Scientific and Technical Information of China (English)

    Luděk Cienciala; Lucie Ciencialová

    2004-01-01

    In this paper the one-way P automata with priorities are introduced. Such automata are P systemshere the membranes are only allowed to consume objects from parent membranes, under the given conditions. The result of computation of these systems is the set of multiset sequences consumed by skin membrane intc the system. The rules associated in some order with each membrane cannot modify any objects, they can only move them through membrane. We show that P automata with priorities and two membranes can accept every recursively enumerated language.

  20. 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....

  1. 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.

  2. 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.

  3. 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.

  4. 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...

  5. 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...

  6. 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

  7. 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.

  8. 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....

  9. 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.

  10. 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.

  11. 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.

  12. 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....

  13. 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.

  14. 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.

  15. 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.

  16. 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.

  17. 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.

  18. 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

  19. How a membrane agent buys goods in a membrane store

    Institute of Scientific and Technical Information of China (English)

    Rudolf Freund; Marion Oswald; Thomas Schirk

    2007-01-01

    In this paper we consider a specific model of membrane systems, i.e. membrane systems with attributes. In these systems, the information is placed at the membranes in form of attributes, no objects are considered inside the membranes except for other membranes. The membrane system with attributes evolves according to rules that compute new values for the attributes from the attributes assigned to the membranes involved in the rule. The model of membrane systems with attributes allows us to specify business transactions in a precise way and to simulate different models for such transactions with a suitable tool for membrane systems with attributes.

  20. 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

  1. 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.

  2. 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.

  3. 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.

  4. 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 ...

  5. 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.

  6. 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

  7. 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

  8. 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.

  9. 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.

  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. 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.

  17. 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

  18. Assessment of the skin irritation hazard of 5 cosmetics using the shell-less hen's egg test chorioallantoic membrane assay%五种化妆品的皮肤刺激性:平皿法鸡胚试验评价

    Institute of Scientific and Technical Information of China (English)

    杨晓冉; 郑洪艳; 董益阳; 王军兵

    2009-01-01

    背景:评价化妆品皮肤刺激性,传统多采用兔皮肤刺激实验,即将化学物涂抹在动物背部去毛的皮肤上,观察其变化,这些方法费时,费力,且给动物带来很大痛苦.各国实验室都在寻找动物替代实验的方法.目的:采用平皿法鸡胚试验方法作为替代方法评价化妆品引起人体皮肤不良反应潜在可能的可行性.设计、时间及地点:动物替代实验,于2008-03/05在中国检验检疫科学研究院毒理学实验室完成.材料:无特定病原体级受精鸡卵,购于北京梅里亚通实验动物技术有限公司.方法:将鸡胚置于平皿中,孵育第8天用于试验,记录出现出血,血管裂解及凝血的鸡胚数目,得出刺激因子X,以判断待测物质是否具有人体皮肤不良反应潜在可能.并与人体斑贴试验结果进行比较.主要观察指标:刺激因子X.结果:5种化妆品中2种有人体皮肤不良反应潜在可能,刺激因子X>5.与人体斑贴试验结果经校正x2 检验比较,差异无显著性意义,其灵敏度、特异度、阳性预测价值、阴性预测价值均为1.结论:平皿法鸡胚试验和人体斑贴试验的结果一致,该方法可以用来评价化妆品的皮肤刺激性.

  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. 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.

  4. 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...

  5. 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.

  6. 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

  7. 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.

  8. 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...

  9. 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...

  10. 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.

  11. 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.)

  12. 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

  13. 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....

  14. 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.

  15. 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).

  16. 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.

  17. 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.

  18. 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.

  19. 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

  20. 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.

  1. 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....

  2. 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.

  3. 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.

  4. 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.

  5. 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.

  6. 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

  7. 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.

  8. 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 ...

  9. 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...

  10. 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.

  11. 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.

  12. 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.

  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. 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.

  15. 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.

  16. 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.

  17. 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.

  18. 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

  19. 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...

  20. 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

  1. 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

  2. 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....

  3. 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.

  4. 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.

  5. 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...

  6. 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

  7. 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

  8. 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.

  9. 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

  10. 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.

  11. 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

  12. 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.

  13. 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.

  14. 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.)

  15. 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

  16. 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...

  17. 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...

  18. 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

  19. 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.

  20. 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

  1. 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

  2. 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.

  3. 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.

  4. 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

  5. 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

  6. 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...

  7. 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

  8. 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.

  9. 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.

  10. Gas Separations using Ceramic Membranes

    Energy Technology Data Exchange (ETDEWEB)

    Paul KT Liu

    2005-01-13

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

  11. 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.

  12. 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.

  13. 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...

  14. 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.

  15. 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.

  16. 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.

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

    Science.gov (United States)

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

    2015-03-01

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

  18. 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...

  19. 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...

  20. 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.

  1. 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

  2. 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 ...

  3. 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

  4. 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.

  5. 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...

  6. 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...

  7. 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

  8. 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.

  9. 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.

  10. 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.

  11. 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.

  12. 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

  13. 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.

  14. 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.

  15. 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.

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

    Science.gov (United States)

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

    2014-09-01

    In this study, two aerobic forward osmosis (FO) membrane bioreactors (MBR) were utilized to treat the effluent of mesophilic (35°C) and atmospheric (25°C) anaerobic MBRs, respectively. The results showed that the FO membrane process could significantly improve the removal efficiencies of N and P. Meanwhile, the flux decline of the FOMBR treating effluent of mesophilic AnMBR (M-FOMBR) was higher than that treating effluent of atmospheric AnMBR (P-FOMBR). The organic membrane foulants in the two FOMBRs were analyzed to understand the membrane fouling behavior in FO processes. It was found that the slightly increased accumulation of protein-like substances into external foulants did not cause faster flux decline in P-FOMBR than that in M-FOMBR. However, the quantity of organic matter tended to deposit or adsorb into FO membrane pores in P-FOMBR was less than that in M-FOMBR, which was accordance with the tendency of membrane fouling indicated by flux decline. PMID:24976492

  17. 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

  18. 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.

  19. 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.

  20. 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.

  1. 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

  2. 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.

  3. 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...

  4. 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.

  5. 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.

  6. 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...

  7. 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...

  8. 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.

  9. 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.

  10. Multilayered Magnetic Gelatin Membrane Scaffolds

    Science.gov (United States)

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

    2016-01-01

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

  11. 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

  12. 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.

  13. 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

  14. 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.

  15. 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...

  16. 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

  17. 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.

  18. 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...

  19. 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...

  20. 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 ...

  1. 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...

  2. 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...

  3. 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

  4. 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.

  5. 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.

  6. 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.

  7. 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)

  8. 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

  9. 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...

  10. 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)

  11. 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

  12. 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.

  13. 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

  14. 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.

  15. 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

  16. 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.

  17. 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.

  18. 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.

  19. 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

  20. 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...

  1. 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.

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

    Science.gov (United States)

    Laible, Philip D; Hanson, Deborah K

    2013-06-04

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

  3. 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.

  4. 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.

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

    KAUST Repository

    Wang, Xianbin

    2015-01-22

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

  6. 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.

  7. Cell Membrane Softening in Cancer Cells

    Science.gov (United States)

    Schmidt, Sebastian; Händel, Chris; Käs, Josef

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

  8. 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.

  9. 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.

  10. 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

  11. 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.

  12. 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...

  13. 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...

  14. 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 ...

  15. 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...

  16. 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...

  17. 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

  18. 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

  19. 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.

  20. 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

  1. 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...

  2. 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.

  3. 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

  4. 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-

  5. 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

  6. 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

  7. 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...

  8. 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

  9. 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

  10. 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

  11. 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

  12. 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

  13. 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.

  14. 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

  15. 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.

  16. 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.

  17. 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...

  18. 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...

  19. 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...

  20. 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

  1. 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

  2. Energy efficiency in membrane bioreactors.

    Science.gov (United States)

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

    2013-01-01

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

  3. 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...

  4. Golgi GRASPs: moonlighting membrane tethers

    Directory of Open Access Journals (Sweden)

    Jarvela T

    2012-05-01

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

  5. 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...

  6. Salt splitting using ceramic membranes

    Energy Technology Data Exchange (ETDEWEB)

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

    1997-10-01

    Many radioactive aqueous wastes in the DOE complex have high concentrations of sodium that can negatively affect waste treatment and disposal operations. Sodium can decrease the durability of waste forms such as glass and is the primary contributor to large disposal volumes. Waste treatment processes such as cesium ion exchange, sludge washing, and calcination are made less efficient and more expensive because of the high sodium concentrations. Pacific Northwest National Laboratory (PNNL) and Ceramatec Inc. (Salt Lake City UT) are developing an electrochemical salt splitting process based on inorganic ceramic sodium (Na), super-ionic conductor (NaSICON) membranes that shows promise for mitigating the impact of sodium. In this process, the waste is added to the anode compartment, and an electrical potential is applied to the cell. This drives sodium ions through the membrane, but the membrane rejects most other cations (e.g., Sr{sup +2}, Cs{sup +}). The charge balance in the anode compartment is maintained by generating H{sup +} from the electrolysis of water. The charge balance in the cathode is maintained by generating OH{sup {minus}}, either from the electrolysis of water or from oxygen and water using an oxygen cathode. The normal gaseous products of the electrolysis of water are oxygen at the anode and hydrogen at the cathode. Potentially flammable gas mixtures can be prevented by providing adequate volumes of a sweep gas, using an alternative reductant or destruction of the hydrogen as it is generated. As H{sup +} is generated in the anode compartment, the pH drops. The process may be operated with either an alkaline (pH>12) or an acidic anolyte (pH <1). The benefits of salt splitting using ceramic membranes are (1) waste volume reduction and reduced chemical procurement costs by recycling of NaOH; and (2) direct reduction of sodium in process streams, which enhances subsequent operations such as cesium ion exchange, calcination, and vitrification.

  7. 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...

  8. 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.

  9. 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...

  10. 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.

  11. 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...

  12. 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...

  13. 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.

  14. 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.

  15. 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.

  16. 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....

  17. 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.

  18. 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...

  19. 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.

  20. 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

  1. 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

  2. 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.

  3. 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....

  4. 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.

  5. 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.

  6. 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.

  7. 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 ...

  8. 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...

  9. 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%.

  10. 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

  11. 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.

  12. 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.

  13. 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.

  14. 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.

  15. 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...

  16. 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.

  17. 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.

  18. 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.

  19. 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.

  20. 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.

  1. 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.

  2. 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.

  3. 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.

  4. 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.

  5. [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.

  6. 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.

  7. 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

  8. 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.

  9. 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.

  10. 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.

  11. 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.

  12. 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

  13. 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

  14. 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.)

  15. 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.

  16. 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...

  17. 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.

  18. 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.

  19. 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...

  20. 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...

  1. 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

  2. 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...

  3. 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...

  4. 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.

  5. 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...

  6. 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.

  7. 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...

  8. 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...

  9. 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.

  10. Ultrafiltration by gyroid nanoporous polymer membranes

    DEFF Research Database (Denmark)

    Li, Li; Szewczykowski, Piotr Przemyslaw; Clausen, Lydia D.;

    2011-01-01

    the effect of membrane fouling on the flux decline and rejection profiles. Significant fouling occurred in the case of hydrophobic membranes in contact with water solutions, while in the presence of high concentration of ethanol in the filtration solution and in the case of hydrophilized membranes......-hydrophilization on permeation and molecular weight cut-off were investigated. Gas permeation followed the Knudsen diffusion scheme, while water flux across the originally hydrophobic membrane could be described by a generalized Hagen–Poiseuille equation. A series of PEGs of different molecular weights were used to explore...... rejection relative to model expectation was found for the hydrophobic membrane in water. For the hydrophilized membrane a sharp increase in rejection from 1kg/mol to 4kg/mol was observed, which only in part could be captured by the model....

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

    KAUST Repository

    An, Alicia Kyoungjin

    2016-07-25

    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 (AR), and acid yellow 36 (AY) 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.

  12. Composite Membrane with Underwater-Oleophobic Surface for Anti-Oil-Fouling Membrane Distillation.

    Science.gov (United States)

    Wang, Zhangxin; Hou, Deyin; Lin, Shihong

    2016-04-01

    In this study, we fabricated a composite membrane for membrane distillation (MD) by modifying a commercial hydrophobic polyvinylidene fluoride (PVDF) membrane with a nanocomposite coating comprising silica nanoparticles, chitosan hydrogel and fluoro-polymer. The composite membrane exhibits asymmetric wettability, with the modified surface being in-air hydrophilic and underwater oleophobic, and the unmodified surface remaining hydrophobic. By comparing the performance of the composite membrane and the pristine PVDF membrane in direct contact MD experiments using a saline emulsion with 1000 ppm crude oil (in water), we showed that the fabricated composite membrane was significantly more resistant to oil fouling compared to the pristine hydrophobic PVDF membrane. Force spectroscopy was conducted for the interaction between an oil droplet and the membrane surface using a force tensiometer. The difference between the composite membrane and the pristine PVDF membrane in their interaction with an oil droplet served to explain the difference in the fouling propensities between these two membranes observed in MD experiments. The results from this study suggest that underwater oleophobic coating can effectively mitigate oil fouling in MD operations, and that the fabricated composite membrane with asymmetric wettability can enable MD to desalinate hypersaline wastewater with high concentrations of hydrophobic contaminants.

  13. Membrane fouling in pilot-scale membrane bioreactors (MBRs) treating municipal wastewater.

    Science.gov (United States)

    Kimura, Katsuki; Yamato, Nobuhiro; Yamamura, Hiroshi; Watanabe, Yoshimasa

    2005-08-15

    The main obstacle for wider use of membrane bioreactors (MBRs) for wastewater treatment is membrane fouling (i.e., deterioration of membrane permeability),which increases operating costs. For more efficient control of membrane fouling in MBRs, an understanding of the mechanisms of membrane fouling is important. However, there is a lack of information on membrane fouling in MBRs, especially information on features of components that are responsible for the fouling. We conducted a pilot-scale experiment using real municipal wastewater with three identical MBRs under different operating conditions. The results obtained in this study suggested that the food-microorganisms ratio (F/M) and membrane filtration flux were the important operating parameters that significantly influenced membrane fouling in MBRs. Neither concentrations of dissolved organic matter in the reactors nor viscosity of mixed liquor, which have been thought to have influences on fouling in MBRs, showed clear relationships with membrane fouling in this study. Organic substances that had caused the membrane fouling were desorbed from fouled membranes of the MBRs at the termination of the operation and were subjected to Fourier transform infrared (FTIR) and 13C nuclear magnetic resonance (NMR) analyses. These analyses revealed that the nature of the membrane foulant changes depending on F/M. It was shown that high F/M would make the foulant more proteinaceous. Carbohydrates were dominant in membrane foulants in this study, while features of humic substances were not apparent.

  14. Membrane transport of hydrogen peroxide.

    Science.gov (United States)

    Bienert, Gerd P; Schjoerring, Jan K; Jahn, Thomas P

    2006-08-01

    Hydrogen peroxide (H2O2) belongs to the reactive oxygen species (ROS), known as oxidants that can react with various cellular targets thereby causing cell damage or even cell death. On the other hand, recent work has demonstrated that H2O2 also functions as a signalling molecule controlling different essential processes in plants and mammals. Because of these opposing functions the cellular level of H2O2 is likely to be subjected to tight regulation via processes involved in production, distribution and removal. Substantial progress has been made exploring the formation and scavenging of H2O2, whereas little is known about how this signal molecule is transported from its site of origin to the place of action or detoxification. From work in yeast and bacteria it is clear that the diffusion of H2O2 across membranes is limited. We have now obtained direct evidence that selected aquaporin homologues from plants and mammals have the capacity to channel H2O2 across membranes. The main focus of this review is (i) to summarize the most recent evidence for a signalling role of H2O2 in various pathways in plants and mammals and (ii) to discuss the relevance of specific transport of H2O2.

  15. Membrane Cholesterol Modulates Superwarfarin Toxicity

    Energy Technology Data Exchange (ETDEWEB)

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

    2016-04-26

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

  16. Membrane Cholesterol Modulates Superwarfarin Toxicity.

    Science.gov (United States)

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

    2016-04-26

    Superwarfarins are modified analogs of warfarin with additional lipophilic aromatic rings, up to 100-fold greater potency, and longer biological half-lives. We hypothesized that increased hydrophobicity allowed interactions with amphiphilic membranes and modulation of biological responses. We find that superwarfarins brodifacoum and difenacoum increase lactate production and cell death in neuroblastoma cells. In contrast, neither causes changes in glioma cells that have higher cholesterol content. After choleterol depletion, lactate production was increased and cell viability was reduced. Drug-membrane interactions were examined by surface X-ray scattering using Langmuir monolayers of dipalmitoylphosphatidylcholine and/or cholesterol. Specular X-ray reflectivity data revealed that superwarfarins, but not warfarin, intercalate between dipalmitoylphosphatidylcholine molecules, whereas grazing incidence X-ray diffraction demonstrated changes in lateral crystalline order of the film. Neither agent showed significant interactions with monolayers containing >20% cholesterol. These findings demonstrate an affinity of superwarfarins to biomembranes and suggest that cellular responses to these agents are regulated by cholesterol content. PMID:27119638

  17. Dysprosium selective potentiometric membrane sensor

    Energy Technology Data Exchange (ETDEWEB)

    Zamani, Hassan Ali, E-mail: haszamani@yahoo.com [Department of Applied Chemistry, Mashhad Branch, Islamic Azad University, Mashhad (Iran, Islamic Republic of); Faridbod, Farnoush; Ganjali, Mohammad Reza [Center of Excellence in Electrochemistry, Faculty of Chemistry, University of Tehran, Tehran (Iran, Islamic Republic of)

    2013-03-01

    A novel Dy(III) ion-selective PVC membrane sensor was made using a new synthesized organic compound, 3,4-diamino-N Prime -((pyridin-2-yl)methylene)benzohydrazide (L) as an excellent sensing element. The electrode showed a Nernstian slope of 19.8 {+-} 0.6 mV per decade in a wide concentration range of 1.0 Multiplication-Sign 10{sup -6}-1.0 Multiplication-Sign 10{sup -2} mol L{sup -1}, a detection limit of 5.5 Multiplication-Sign 10{sup -7} mol L{sup -1}, a short conditioning time, a fast response time (< 10 s), and high selectivity towards Dy(III) ion in contrast to other cations. The proposed sensor was successfully used as an indicator electrode in the potentiometric titration of Dy(III) ions with EDTA. The membrane sensor was also applied to the F{sup -} ion indirect determination of some mouth washing solutions and to the Dy{sup 3+} determination in binary mixtures. Highlights: Black-Right-Pointing-Pointer The novelty of this work is based on the high affinity of the ionophore toward the Dy{sup 3+} ions. Black-Right-Pointing-Pointer This technique is very simple, fast and inexpensive and it is not necessary to use sophisticated equipment. Black-Right-Pointing-Pointer The newly developed sensor is superior to the formerly reported Dy{sup 3+} sensors in terms of selectivity.

  18. Membrane Organization and Dynamics in Cell Polarity

    OpenAIRE

    Orlando, Kelly; Guo, Wei

    2009-01-01

    The establishment and maintenance of cell polarity is important to a wide range of biological processes ranging from chemotaxis to embryogenesis. An essential feature of cell polarity is the asymmetric organization of proteins and lipids in the plasma membrane. In this article, we discuss how polarity regulators such as small GTP-binding proteins and phospholipids spatially and kinetically control vesicular trafficking and membrane organization. Conversely, we discuss how membrane trafficking...

  19. Filterability and Sludge Concentration in Membrane Bioreactors

    OpenAIRE

    Lousada-Ferreira, M

    2011-01-01

    The Thesis entitled “Filterability and Sludge Concentration in Membrane Bioreactors” aims at explaining the relation between Mixed Liquid Suspended Solids (MLSS) concentration, the amount of solids in the wastewater being treated, also designated as sludge, and filterability, being the ability of the sludge to be filtrated through a membrane, in a wastewater treatment system designated as Membrane Bioreactor (MBR). An MBR is a wastewater treatment system that combines an activated sludge proc...

  20. Progress in surface and membrane science

    CERN Document Server

    Cadenhead, D A; Rosenberg, M D

    1975-01-01

    Progress in Surface and Membrane Science, Volume 9 covers the developments in surface and membrane science. The book discusses the physical adsorption of gases and vapors in micropores; the chemisorption theory; and the role of radioisotopes in the studies of chemisorption and catalysis. The text also describes the interaction of ions with monolayers; and the isolation and characterization of mycoplasma membranes. Chemists, physical chemists, and microbiologists will find the book useful.

  1. Membranes as separators of dispersed emulsion phases.

    OpenAIRE

    Lefferts, A.G.

    1997-01-01

    The reuse or discharge of industrial waste waters, containing small fractions of dispersed oil, requires a purification treatment for which membranes can be used. If only little oil is present, removal of the dispersed phase might be preferable to the more commonly applied removal of the continuous phase. For this purpose dispersed phase separators can be applied, which combine the features of conventional coalescers and membrane filtration. The membrane surface promotes coalescence (similar ...

  2. Model Answers to Lipid Membrane Questions

    DEFF Research Database (Denmark)

    Mouritsen, O. G.

    2011-01-01

    Ever since it was discovered that biological membranes have a core of a bimolecular sheet of lipid molecules, lipid bilayers have been a model laboratory for investigating physicochemical and functional properties of biological membranes. Experimental and theoretical models help the experimental...... to pursue. Here we review some membrane models for lipid self-assembly, monolayers, bilayers, liposomes, and lipid-protein interactions and illustrate how such models can help answering questions in modern lipid cell biology....

  3. Tides on Europa: the membrane paradigm

    CERN Document Server

    Beuthe, Mikael

    2014-01-01

    Jupiter's moon Europa has a thin icy crust which is decoupled from the mantle by a subsurface ocean. The crust thus responds to tidal forcing as a deformed membrane, cold at the top and near melting point at the bottom. In this paper I develop the membrane theory of viscoelastic shells with depth-dependent rheology with the dual goal of predicting tidal tectonics and computing tidal dissipation. Two parameters characterize the tidal response of the membrane: the effective Poisson's ratio $\\bar\

  4. Asymmetric Membrane Osmotic Capsules for Terbutaline Sulphate

    OpenAIRE

    Gobade, N. G.; Marina Koland; K H Harish

    2012-01-01

    The aim of the present study was to design an asymmetric membrane capsule, an osmotic pump-based drug delivery system of ethyl cellulose for controlled release of terbutaline sulphate. asymmetric membrane capsules contains pore-forming water soluble additive, sorbitol in different concentrations in the capsule shell membrane, which after coming in contact with water, dissolves, resulting in an in situ formation of a microporous structure. The terbutaline sulphate is a β-adrenoreceptor agonist...

  5. Biogenesis and Membrane Targeting of Lipoproteins.

    Science.gov (United States)

    Narita, Shin-Ichiro; Tokuda, Hajime

    2010-09-01

    Bacterial lipoproteins represent a unique class of membrane proteins, which are anchored to membranes through triacyl chains attached to the amino-terminal cysteine. They are involved in various functions localized in cell envelope. Escherichia coli possesses more than 90 species of lipoproteins, most of which are localized in the outer membrane, with others being in the inner membrane. All lipoproteins are synthesized in the cytoplasm with an N-terminal signal peptide, translocated across the inner membrane by the Sec translocon to the periplasmic surface of the inner membrane, and converted to mature lipoproteins through sequential reactions catalyzed by three lipoprotein-processing enzymes: Lgt, LspA, and Lnt. The sorting of lipoproteins to the outer membrane requires a system comprising five Lol proteins. An ATP-binding cassette transporter, LolCDE, initiates the sorting by mediating the detachment of lipoproteins from the inner membrane. Formation of the LolA-lipoprotein complex is coupled to this LolCDE-dependent release reaction. LolA accommodates the amino-terminal acyl chain of lipoproteins in its hydrophobic cavity, thereby generating a hydrophilic complex that can traverse the periplasmic space by diffusion. Lipoproteins are then transferred to LolB on the outer membrane and anchored to the inner leaflet of the outer membrane by the action of LolB. In contrast, since LolCDE does not recognize lipoproteins possessing Asp at position +2, these lipoproteins remain anchored to the inner membrane. Genes for Lol proteins are widely conserved among gram-negative bacteria, and Lol-mediated outer membrane targeting of lipoproteins is considered to be the general lipoprotein localization mechanism. PMID:26443779

  6. Recent Membrane Development for Pervaporation Processes

    KAUST Repository

    Ong, Yee Kang

    2016-03-11

    Pervaporation has been regarded as a promising separation technology in separating azeotropic mixtures, solutions with similar boiling points, thermally sensitive compounds, organic–organic mixtures as well as in removing dilute organics from aqueous solutions. As the pervaporation membrane is one of the crucial factors in determining the overall efficiency of the separation process, this article reviews the research and development (R&D) of polymeric pervaporation membranes from the perspective of membrane fabrication procedures and materials.

  7. Long term testing of PSI-membranes

    Energy Technology Data Exchange (ETDEWEB)

    Huslage, J.; Brack, H.P.; Geiger, F.; Buechi, F.N.; Tsukada, A.; Scherer, G.G. [Paul Scherrer Inst. (PSI), Villigen (Switzerland)

    1999-08-01

    Long term tests of PSI membranes based on radiation-grafted FEP and ETFE films were carried out and FEP-based membranes were evaluated by monitoring the in-situ membrane area resistance measured by a current pulse method. By modifying our irradiation procedure and using the double crosslinking concept we obtain reproducible membrane cell lifetimes (in term of in-situ membrane resistance) of greater than 5000 hours at 60-65{sup o}C. Preliminary tests at 80-85{sup o}C with lifetimes of greater than 2500 demonstrate the potential long term stability of PSI proton exchange membranes based on FEP over the whole operating temperature range of low-temperature polymer electrolyte fuel cells. Radiation grafted PSI membranes based on ETFE have better mechanical properties than those of the FEP membranes. Mechanical properties are particularly important in large area cells and fuel cell stacks. ETFE membranes have been tested successfully for approximately 1000 h in a 2-cell stack (100 cm{sup 2} active area each cell). (author) 4 figs., 4 refs.

  8. Progress in surface and membrane science

    CERN Document Server

    Danielli, J F; Cadenhead, D A

    1972-01-01

    Progress in Surface and Membrane Science, Volume 5 covers the developments in the study of surface and membrane science. The book discusses the Mössbauer effect in surface science; the surface functional groups on carbon and silica; and the wetting phenomena pertaining to adhesion. The text also describes the physical state of phospholipids and cholesterol in monolayers, bilayers, and membranes; the characteristics of heterocoagulation; and the effects of calcium on excitable membranes and neurotransmitter action. Chemists, physiologists, biophysicists, and civil engineers will find the book i

  9. Composite membranes and methods for making same

    Science.gov (United States)

    Routkevitch, Dmitri; Polyakov, Oleg G

    2012-07-03

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

  10. Fouling distribution in forward osmosis membrane process.

    Science.gov (United States)

    Lee, Junseok; Kim, Bongchul; Hong, Seungkwan

    2014-06-01

    Fouling behavior along the length of membrane module was systematically investigated by performing simple modeling and lab-scale experiments of forward osmosis (FO) membrane process. The flux distribution model developed in this study showed a good agreement with experimental results, validating the robustness of the model. This model demonstrated, as expected, that the permeate flux decreased along the membrane channel due to decreasing osmotic pressure differential across the FO membrane. A series of fouling experiments were conducted under the draw and feed solutions at various recoveries simulated by the model. The simulated fouling experiments revealed that higher organic (alginate) fouling and thus more flux decline were observed at the last section of a membrane channel, as foulants in feed solution became more concentrated. Furthermore, the water flux in FO process declined more severely as the recovery increased due to more foulants transported to membrane surface with elevated solute concentrations at higher recovery, which created favorable solution environments for organic adsorption. The fouling reversibility also decreased at the last section of the membrane channel, suggesting that fouling distribution on FO membrane along the module should be carefully examined to improve overall cleaning efficiency. Lastly, it was found that such fouling distribution observed with co-current flow operation became less pronounced in counter-current flow operation of FO membrane process.

  11. Progress in surface and membrane science

    CERN Document Server

    Cadenhead, D A; Rosenberg, M D

    1974-01-01

    Progress in Surface and Membrane Science, Volume 8 covers the developments in the study of surface and membrane science. The book discusses the applications of statistical mechanics to physical adsorption; the impact of electron spectroscopy and cognate techniques on the study of solid surfaces; and the ellipsometric studies of thin films. The text also describes the interfacial photochemistry of bilayer lipid membranes; cell junctions and their development; and the composition and function of the inner mitochondrial membrane. The role of the cell surface in contact inhibition of cell division

  12. Effects of protein crowding on membrane systems.

    Science.gov (United States)

    Guigas, Gernot; Weiss, Matthias

    2016-10-01

    Cellular membranes are typically decorated with a plethora of embedded and adsorbed macromolecules, e.g. proteins, that participate in numerous vital processes. With typical surface densities of 30,000 proteins per μm(2) cellular membranes are indeed crowded places that leave only few nanometers of private space for individual proteins. Here, we review recent advances in our understanding of protein crowding in membrane systems. We first give a brief overview on state-of-the-art approaches in experiment and simulation that are frequently used to study crowded membranes. After that, we review how crowding can affect diffusive transport of proteins and lipids in membrane systems. Next, we discuss lipid and protein sorting in crowded membrane systems, including effects like protein cluster formation, phase segregation, and lipid droplet formation. Subsequently, we highlight recent progress in uncovering crowding-induced conformational changes of membranes, e.g. membrane budding and vesicle formation. Finally, we give a short outlook on potential future developments in the field of crowded membrane systems. This article is part of a Special Issue entitled: Biosimulations edited by Ilpo Vattulainen and Tomasz Róg. PMID:26724385

  13. Membrane Technologies in Wine Industry: An Overview.

    Science.gov (United States)

    El Rayess, Youssef; Mietton-Peuchot, Martine

    2016-09-01

    Membrane processes are increasingly reported for various applications in wine industry such as microfiltration, electrodialysis, and reverse osmosis, but also emerging processes as bipolar electrodialysis and membrane contactor. Membrane-based processes are playing a critical role in the field of separation/purification, clarification, stabilization, concentration, and de-alcoholization of wine products. They begin to be an integral part of the winemaking process. This review will provide an overview of recent developments, applications, and published literature in membrane technologies applied in wine industry. PMID:25751507

  14. Light Responsive Polymer Membranes: A Review

    Directory of Open Access Journals (Sweden)

    Fiore Pasquale Nicoletta

    2012-03-01

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

  15. MEMBRANE BIOREACTOR FOR TREATMENT OF RECALCITRANT WASTEWATERS

    Directory of Open Access Journals (Sweden)

    Suprihatin Suprihatin

    2012-02-01

    Full Text Available The low biodegradable wastewaters remain a challenge in wastewater treatment technology. The performance of membrane bioreactor systems with submerged hollow fiber micro- and ultrafiltration membrane modules were examined for purifying recalcitrant wastewaters of leachate of a municipal solid waste open dumping site and effluent of pulp and paper mill. The use of MF and UF membrane bioreactor systems showed an efficient treatment for both types wastewaters with COD reduction of 80-90%. The membrane process achieved the desirable effects of maintaining reasonably high biomass concentration and long sludge retention time, while producing a colloid or particle free effluent. For pulp and paper mill effluent a specific sludge production of 0.11 kg MLSS/kg COD removed was achieved. A permeate flux of about 5 L/m²h could be achieved with the submerged microfiltration membrane. Experiments using ultrafiltration membrane produced relatively low permeate fluxes of 2 L/m²h. By applying periodical backwash, the flux could be improved significantly. It was indicated that the particle or colloid deposition on membrane surface was suppressed by backwash, but reformation of deposit was not effectively be prevented by shear-rate effect of aeration. Particle and colloid started to accumulate soon after backwash. Construction of membrane module and operation mode played a critical role in achieving the effectiveness of aeration in minimizing deposit formation on the membrane surface.

  16. Tensile strain mapping in flat germanium membranes

    Energy Technology Data Exchange (ETDEWEB)

    Rhead, S. D., E-mail: S.Rhead@warwick.ac.uk; Halpin, J. E.; Myronov, M.; Patchett, D. H.; Allred, P. S.; Wilson, N. R.; Leadley, D. R. [Department of Physics, University of Warwick, Coventry, CV4 7AL (United Kingdom); Shah, V. A. [Department of Physics, University of Warwick, Coventry, CV4 7AL (United Kingdom); Department of Engineering, University of Warwick, Coventry, CV4 7AL (United Kingdom); Kachkanov, V.; Dolbnya, I. P. [Diamond Light Source, Harwell Science and Innovation Campus, Didcot, Oxfordshire, OX11 0DE (United Kingdom); Reparaz, J. S. [ICN2 - Institut Catala de Nanociencia i Nanotecnologia, Campus UAB, 08193 Bellaterra (Barcelona) (Spain); Sotomayor Torres, C. M. [ICN2 - Institut Catala de Nanociencia i Nanotecnologia, Campus UAB, 08193 Bellaterra (Barcelona) (Spain)

    2014-04-28

    Scanning X-ray micro-diffraction has been used as a non-destructive probe of the local crystalline quality of a thin suspended germanium (Ge) membrane. A series of reciprocal space maps were obtained with ∼4 μm spatial resolution, from which detailed information on the strain distribution, thickness, and crystalline tilt of the membrane was obtained. We are able to detect a systematic strain variation across the membranes, but show that this is negligible in the context of using the membranes as platforms for further growth. In addition, we show evidence that the interface and surface quality is improved by suspending the Ge.

  17. Tensile strain mapping in flat germanium membranes

    International Nuclear Information System (INIS)

    Scanning X-ray micro-diffraction has been used as a non-destructive probe of the local crystalline quality of a thin suspended germanium (Ge) membrane. A series of reciprocal space maps were obtained with ∼4 μm spatial resolution, from which detailed information on the strain distribution, thickness, and crystalline tilt of the membrane was obtained. We are able to detect a systematic strain variation across the membranes, but show that this is negligible in the context of using the membranes as platforms for further growth. In addition, we show evidence that the interface and surface quality is improved by suspending the Ge

  18. Aquaporin, forward osmosis and biomimetic membranes.

    Science.gov (United States)

    Kocherginsky, Nikolai

    2013-12-01

    Aquaporin attracted attention not only of physiologists and biophysicists, but also of chemical engineers. Here we critically analyze a paper describing aquaporin-based artificial membranes, suggested for forward osmosis-based water purification (Wang et al. 2012, Small 8, pp. 1185-1190). Related papers published later by the same group are also discussed. We indicate recently developed general approach to describe membrane transport, membrane permeability and selectivity, which is applicable for forward osmosis. In addition, we also mention our papers describing simple nitrocellulose-based membranes, which have selective aqueous channels without proteins, but successfully imitate many properties of biomembranes. PMID:24434310

  19. Heterogeneous Photooxidation of Phenol by Catalytic Membranes

    Institute of Scientific and Technical Information of China (English)

    Enrica Fontananova; Enrico Drioli; Laura Donato; Marcella Bonchio; Mauro Carraro; Gianfranco Scorrano

    2006-01-01

    In this work the heterogenization in polymeric membranes of decatungstate, a photocatalyst for oxidation reactions,was reported. Solid state characterization techniques confirmed that the catalyst structure was preserved within the polymeric membranes. The catalytic membranes were successfully applied in the aerobic photo-oxidation of phenol, one of the main organic pollutants in wastewater, providing stable and recyclable photocatalytic systems. The dependence of the phenol degradation rate by the catalyst loading and transmembrane pressure was shown. By comparison with homogeneous reaction,the catalyst heterogenized in membrane appears to be more efficient concerning the rate of phenol photodegradation and mineralization.

  20. Prediction of wrinkles in the membrane

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    This paper presents an analytical approach for predicting the detailed out-of-plane wrinkle deformation that formed in the membrane. The analytical wrinkle model is based on the assumption that the membrane is able to resist small compressive stress once it has wrinkled. This model is developed for the cases of the rectangular membrane subjected to pure shear and local tension by using the equilibrium equation of the membrane in the deformed configuration. Predictions from this model are compared with the finite element simulation based on the nonlinear buckling finite element method and the results are found to be accurate.

  1. Modeling anisotropic elasticity of fluid membranes

    CERN Document Server

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

    2011-01-01

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

  2. Rejection of pharmaceuticals by forward osmosis membranes.

    Science.gov (United States)

    Jin, Xue; Shan, Junhong; Wang, Can; Wei, Jing; Tang, Chuyang Y

    2012-08-15

    Rejection of four pharmaceutical compounds, carbamazepine, diclofenac, ibuprofen and naproxen, by forward osmosis (FO) membranes was investigated in this study. For the first time, the rejection efficiency of the pharmaceutical compounds was compared between commercial cellulose triacetate (CTA) based membranes and thin film composite (TFC) polyamide based membranes. The rejection behavior was related to membrane interfacial properties, physicochemical characteristics of the pharmaceutical molecules and feed solution pH. TFC polyamide membranes exhibited excellent overall performance, with high water flux, excellent pH stability and great rejection of all pharmaceuticals investigated (>94%). For commercial CTA based FO membranes, hydrophobic interaction between the compounds and membranes exhibited strong influence on their rejection under acidic conditions. The pharmaceuticals rejection was well correlated to their hydrophobicity (log D). Under alkaline conditions, both electrostatic repulsion and size exclusion contributed to the removal of deprotonated molecules. The pharmaceuticals rejection by CTA-HW membrane at pH 8 followed the order: diclofenac (99%)>carbamazepine (95%)>ibuprofen (93%) ≈ naproxen (93%). These results can be important for FO membrane synthesis, modification and their application in water purification. PMID:22640821

  3. Failure Modes of thin supported Membranes

    DEFF Research Database (Denmark)

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

    2007-01-01

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

  4. Progress in surface and membrane science

    CERN Document Server

    Cadenhead, D A

    1976-01-01

    Progress in Surface and Membrane Science, Volume 10 covers the advances in surface and membrane science. The book discusses the selective changes of cellular particles influencing sedimentation properties; and the rotating disk and ring-disk electrodes in investigations of surface phenomena at the metal-electrolyte interface. The text also describes the membrane potential of phospholipid bilayer and biological membranes; the adsorption of surfactant monolayers at gas/liquid and liquid/liquid interfaces; and the enzymes immobilized on glass. Chemists and people involved in electrochemistry will

  5. Microfluidic microbial fuel cells: from membrane to membrane free

    Science.gov (United States)

    Yang, Yang; Ye, Dingding; Li, Jun; Zhu, Xun; Liao, Qiang; Zhang, Biao

    2016-08-01

    Microfluidic microbial fuel cells (MMFCs) are small carbon-neutral devices that use self-organized bacteria to degrade organic substrates and harness energy from the waste water. Conventional MMFCs have made great strides in the past decade and have overcome some limitations, such as high capital costs and low energy output. A co-laminar flow MFC has been first proposed in 2011 with the potential to be an attractively power source to niche applications. Co-laminar MFCs typically operate without any physical membranes separating the reactants, and bacterial ecosystems can be easily manipulated by regulating the inlet conditions. This paper highlights recent accomplishments in the development of co-laminar MFCs, emphasizing basic principles, mass transport and fluid dynamics including boundary layer theory, entrance conditions and mixing zone issues. Furthermore, the development of current techniques, major challenges and the potential research directions are discussed.

  6. Reconstitution of the membrane protein OmpF into biomimetic block copolymer–phospholipid hybrid membranes

    Science.gov (United States)

    Bieligmeyer, Matthias; Artukovic, Franjo; Hirth, Thomas; Schiestel, Thomas

    2016-01-01

    Summary Structure and function of many transmembrane proteins are affected by their environment. In this respect, reconstitution of a membrane protein into a biomimetic polymer membrane can alter its function. To overcome this problem we used membranes formed by poly(1,4-isoprene-block-ethylene oxide) block copolymers blended with 1,2-diphytanoyl-sn-glycero-3-phosphocholine. By reconstituting the outer membrane protein OmpF from Escherichia coli into these membranes, we demonstrate functionality of this protein in biomimetic lipopolymer membranes, independent of the molecular weight of the block copolymers. At low voltages, the channel conductance of OmpF in 1 M KCl was around 2.3 nS. In line with these experiments, integration of OmpF was also revealed by impedance spectroscopy. Our results indicate that blending synthetic polymer membranes with phospholipids allows for the reconstitution of transmembrane proteins under preservation of protein function, independent of the membrane thickness. PMID:27547605

  7. Membrane fouling control using a rotary disk in a submerged anaerobic membrane sponge bioreactor.

    Science.gov (United States)

    Kim, Jungmin; Shin, Jaewon; Kim, Hyemin; Lee, Jung-Yeol; Yoon, Min-Hyuk; Won, Seyeon; Lee, Byung-Chan; Song, Kyung Guen

    2014-11-01

    Despite significant research efforts over the last few decades, membrane fouling in anaerobic membrane bioreactors (AnMBRs) remains an unsolved problem that increases the overall operational costs and obstructs the industrial applications. Herein, we developed a method for effectively controlling the membrane fouling in a sponge-submerged AnMBRs using an anaerobic rotary disk MBR (ARMBR). The disk rotation led the effective collision between the sponge and membrane surface; thus successfully enhanced the membrane permeability in the ARMBR. The effect of the disk rotational speed and sponge volume fraction on the membrane permeability and the relationship between the water flow direction and membrane permeability were investigated. The long-term feasibility was tested over 100days of synthetic wastewater treatment. As a result, stable and economical performance was observed without membrane replacement and washing. The proposed integrated rotary disk-supporting media appears to be a feasible and even beneficial option in the AnMBR technology. PMID:25277260

  8. Membrane Compartmentalization Reducing the Mobility of Lipids and Proteins within a Model Plasma Membrane.

    Science.gov (United States)

    Koldsø, Heidi; Reddy, Tyler; Fowler, Philip W; Duncan, Anna L; Sansom, Mark S P

    2016-09-01

    The cytoskeleton underlying cell membranes may influence the dynamic organization of proteins and lipids within the bilayer by immobilizing certain transmembrane (TM) proteins and forming corrals within the membrane. Here, we present coarse-grained resolution simulations of a biologically realistic membrane model of asymmetrically organized lipids and TM proteins. We determine the effects of a model of cytoskeletal immobilization of selected membrane proteins using long time scale coarse-grained molecular dynamics simulations. By introducing compartments with varying degrees of restraints within the membrane models, we are able to reveal how compartmentalization caused by cytoskeletal immobilization leads to reduced and anomalous diffusional mobility of both proteins and lipids. This in turn results in a reduced rate of protein dimerization within the membrane and of hopping of membrane proteins between compartments. These simulations provide a molecular realization of hierarchical models often invoked to explain single-molecule imaging studies of membrane proteins.

  9. Reconstitution of the membrane protein OmpF into biomimetic block copolymer–phospholipid hybrid membranes

    Science.gov (United States)

    Bieligmeyer, Matthias; Artukovic, Franjo; Hirth, Thomas; Schiestel, Thomas

    2016-01-01

    Summary Structure and function of many transmembrane proteins are affected by their environment. In this respect, reconstitution of a membrane protein into a biomimetic polymer membrane can alter its function. To overcome this problem we used membranes formed by poly(1,4-isoprene-block-ethylene oxide) block copolymers blended with 1,2-diphytanoyl-sn-glycero-3-phosphocholine. By reconstituting the outer membrane protein OmpF from Escherichia coli into these membranes, we demonstrate functionality of this protein in biomimetic lipopolymer membranes, independent of the molecular weight of the block copolymers. At low voltages, the channel conductance of OmpF in 1 M KCl was around 2.3 nS. In line with these experiments, integration of OmpF was also revealed by impedance spectroscopy. Our results indicate that blending synthetic polymer membranes with phospholipids allows for the reconstitution of transmembrane proteins under preservation of protein function, independent of the membrane thickness.

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

    Institute of Scientific and Technical Information of China (English)

    Sun Qianyao; Xu Chunming

    2007-01-01

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

  11. Nanocomposite Membranes based on Perlfuorosulfonic Acid/Ceramic for Proton Exchange Membrane Fuel Cells

    Institute of Scientific and Technical Information of China (English)

    LI Qiong; WANG Guangjin; YE Hong; YAN Shilin

    2015-01-01

    Perlfuorosulfonic acid/ceramic nanocomposite membranes were investigated as electrolytes for polymer electrolyte membrane fuel cell applications under low relative humidity. Different nanosized ceramics (SiO2, ZrO2, TiO2) with diameters in the range of 2-6 nm were synthesized in situ in Nafion solution through a sol-gel process and the formed nanosized ceramics were well-dispersed in the solution. The nanocomposite membranes were formed through a casting process. The nanocomposite membrane showes enhanced water retention ability and improved proton conductivity compared to those of pure Naifon membrane. The mechanical strength of the formed nanocomposite membranes is slightly less than that of pure Naifon membrane. The experimental results demonstrate that the polymer ceramic nanocompsite membranes are potential electrolyte for fuel cells operating at elevated temperature.

  12. The application of Dow Chemical's perfluorinated membranes in proton-exchange membrane fuel cells

    Science.gov (United States)

    Eisman, G. A.

    1990-02-01

    Dow Chemical's research activities in fuel cells revolve around the development of perfluorosulfonic acid membranes, useful as the proton transport medium and separator. The following work will outline some of the performance characteristics which are typical for such membranes.

  13. Mathematical Model of Gas Permeation Through PTFEP orous Membrane and the Effect of Membrane Pore Structure

    Institute of Scientific and Technical Information of China (English)

    张秀莉; 张卫东; 郝新政; 张慧峰; 张泽廷; 张建春

    2003-01-01

    Membrane-based separation processes are new technology combined membrane separation with conventional separation. Hydrophobic porous membranes are often used in these processes. The structure of hydrophobic porous membrane has significant effect on mass transfer process. The permeabilities of five kinds of gas, He, N2,O2, CO2 and water vapor, across six polytetrafluoroethylene(PTFE) fiat membranes were tested experimentally.Results indicated that the greater the membrane mean pore size and the wider the pore size distribution are, the higher the gas permeability. A gas permeation model, including the effects of membrane structure parameter and gas properties, was established. A comprehensive characteristic parameter (including porosity, thickness and tortuosity) was found more effective to express the influence of membrane structure in gas permeation process. The predicted permeation coefficients were in good agreement with experimental data.

  14. Proteopolymersomes: in vitro production of a membrane protein in polymersome membranes.

    Science.gov (United States)

    Nallani, Madhavan; Andreasson-Ochsner, Mirjam; Tan, Cherng-Wen Darren; Sinner, Eva-Kathrin; Wisantoso, Yudi; Geifman-Shochat, Susana; Hunziker, Walter

    2011-12-01

    Polymersomes are stable self-assembled architectures which mimic cell membranes. For characterization, membrane proteins can be incorporated into such bio-mimetic membranes by reconstitution methods, leading to so-called proteopolymersomes. In this work, we demonstrate the direct incorporation of a membrane protein into polymersome membranes by a cell-free expression system. Firstly, we demonstrate pore formation in the preformed polymersome membrane using α-hemolysin. Secondly, we use claudin-2, a protein involved in cell-cell interactions, to demonstrate the in vitro expression of a membrane protein into these polymersomes. Surface plasmon resonance (Biacore) binding studies with the claudin-2 proteopolymersomes and claudin-2 specific antibodies are performed to show the presence of the in vitro expressed protein in polymersome membranes.

  15. Study of polytopic membrane protein topological organization as a function of membrane lipid composition.

    Science.gov (United States)

    Bogdanov, Mikhail; Heacock, Philip N; Dowhan, William

    2010-01-01

    A protocol is described using lipid mutants and thiol-specific chemical reagents to study lipid-dependent and host-specific membrane protein topogenesis by the substituted-cysteine accessibility method as applied to transmembrane domains (SCAM). SCAM is adapted to follow changes in membrane protein topology as a function of changes in membrane lipid composition. The strategy described can be adapted to any membrane system. PMID:20419405

  16. Membrane curvature enables N-Ras lipid anchor sorting to liquid-ordered membrane phases

    DEFF Research Database (Denmark)

    Larsen, Jannik Bruun; Jensen, Martin Borch; Bhatia, Vikram Kjøller;

    2015-01-01

    Trafficking and sorting of membrane-anchored Ras GTPases are regulated by partitioning between distinct membrane domains. Here, in vitro experiments and microscopic molecular theory reveal membrane curvature as a new modulator of N-Ras lipid anchor and palmitoyl chain partitioning. Membrane...... curvature was essential for enrichment in raft-like liquid-ordered phases; enrichment was driven by relief of lateral pressure upon anchor insertion and most likely affects the localization of lipidated proteins in general....

  17. Correlated Diffusion of Membrane Proteins and Their Effect on Membrane Viscosity

    OpenAIRE

    Oppenheimer, Naomi; Diamant, Haim

    2009-01-01

    We extend the Saffman theory of membrane hydrodynamics to account for the correlated motion of membrane proteins, along with the effect of protein concentration on that correlation and on the response of the membrane to stresses. Expressions for the coupling diffusion coefficients of protein pairs and their concentration dependence are derived in the limit of small protein size relative to the inter-protein separation. The additional role of membrane viscosity as determining the characteristi...

  18. Membrane bending is critical for the stability of voltage sensor segments in the membrane

    OpenAIRE

    Callenberg, Keith M; Latorraca, Naomi R.; Grabe, Michael

    2012-01-01

    The interaction between membrane proteins and the surrounding membrane is becoming increasingly appreciated for its role in regulating protein function, protein localization, and membrane morphology. In particular, recent studies have suggested that membrane deformation is needed to stably accommodate proteins harboring charged amino acids in their transmembrane (TM) region, as it is energetically prohibitive to bury charge in the hydrophobic core of the bilayer. Unfortunately, current comput...

  19. Biomimetic triblock copolymer membrane arrays: a stable template for functional membrane proteins

    DEFF Research Database (Denmark)

    Gonzalez-Perez, A.; Jensen, Karin Bagger Stibius; Vissing, Thomas;

    2009-01-01

    It is demonstrated that biomimetic stable triblock copolymer membrane arrays can be prepared using a scaffold containing 64 apertures of 300 μm diameter each. The membranes were made from a stock solution of block copolymers with decane as a solvent using a new deposition method. By using decane,...... to what is observed in black lipid membranes. The ion-channel gramicidin A was successfully incorporated into the membrane in a functional form....

  20. Role of the membrane skeleton in preventing the shedding of procoagulant-rich microvesicles from the platelet plasma membrane

    OpenAIRE

    1990-01-01

    The platelet plasma membrane is lined by a membrane skeleton that appears to contain short actin filaments cross-linked by actin-binding protein. Actin-binding protein is in turn associated with specific plasma membrane glycoproteins. The aim of this study was to determine whether the membrane skeleton regulates properties of the plasma membrane. Platelets were incubated with agents that disrupted the association of the membrane skeleton with membrane glycoproteins. The consequences of this c...

  1. Nafion/Silicon Oxide Composite Membrane for High Temperature Proton Exchange Membrane Fuel Cell

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    Nafion/Silicon oxide composite membranes were produced via in situ sol-gel reaction of tetraethylorthosilicate (TEOS) in Nafion membranes. The physicochemical properties of the membranes were studied by FT-IR, TG-DSC and tensile strength. The results show that the silicon oxide is compatible with the Nafion membrane and the thermo stability of Nafion/Silicon oxide composite membrane is higher than that of Nafion membrane. Furthermore, the tensile strength of Nafion/Silicon oxide composite membrane is similar to that of the Nafion membrane. The proton conductivity of Nafion/Silicon oxide composite membrane is higher than that of Nafion membrane. When the Nafion/Silicon oxide composite membrane was employed as an electrolyte in H2/O2 PEMFC, a higher current density value (1 000 mA/cm2 at 0.38 V) than that of the Nafion 1135 membrane (100 mA/cm2 at 0.04 V) was obtained at 110 ℃.

  2. Development of composite membranes of PVA-TEOS doped KOH for alkaline membrane fuel cell

    International Nuclear Information System (INIS)

    Anion exchange membranes (AEMs) play an important role in separating fuel and oxygen (or air) in the Alkaline Membrane Fuel Cells. Preparation of hybrid organic inorganic materials of Polyvinylalcohol (PVA) - Tetraethylorthosilicate (TEOS) composite membrane doped KOH for direct alcohol alkaline fuel cell application has been investigated. The sol-gel method has been used to prepare the composite membrane of PVA-TEOS through crosslinking step and catalyzed by concentrated of hydrochloric acid. The gel solution was cast on the membrane plastic plate to obtain membrane sheets. The dry membranes were then doped by immersing in various concentrations of KOH solutions for about 4 hours. Investigations of the cross-linking process and the presence of hydroxyl group were conducted by FTIR as shown for frequency at about 1600 cm−1 and 3300 cm−1 respectively. The degree of swelling in ethanol decreased as the KOH concentration for membrane soaking process increased. The ion exchange capacity (IEC) of the membrane was 0.25meq/g. This composite membranes display significant ionic conductivity of 3.23 x 10−2 S/cm in deionized water at room temperature. In addition, the morphology observation by scanning electron microscope (SEM) of the membrane indicates that soaking process of membrane in KOH increased thermal resistant

  3. Dependence of Shear and Concentration on Fouling in a Membrane Bioreactor with Rotating Membrane Discs

    DEFF Research Database (Denmark)

    Jørgensen, Mads Koustrup; Pedersen, Malene Thostrup; Christensen, Morten Lykkegaard;

    2014-01-01

    Rotating ceramic membrane discs were fouled with lab-scale membrane bioreactors (MBR) sludge. Sludge filtrations were performed at varying rotation speeds and in different concentric rings of the membranes on different sludge concentrations. Data showed that the back transport expressed by limiting...

  4. Development of composite membranes of PVA-TEOS doped KOH for alkaline membrane fuel cell

    Energy Technology Data Exchange (ETDEWEB)

    Haryadi,, E-mail: haryadi@polban.ac.id; Sugianto, D.; Ristopan, E. [Department of Chemical Engineering, Politeknik Negeri Bandung Jl. Gegerkalong Hilir, Ds. Ciwaruga, Bandung West Java (Indonesia)

    2015-12-29

    Anion exchange membranes (AEMs) play an important role in separating fuel and oxygen (or air) in the Alkaline Membrane Fuel Cells. Preparation of hybrid organic inorganic materials of Polyvinylalcohol (PVA) - Tetraethylorthosilicate (TEOS) composite membrane doped KOH for direct alcohol alkaline fuel cell application has been investigated. The sol-gel method has been used to prepare the composite membrane of PVA-TEOS through crosslinking step and catalyzed by concentrated of hydrochloric acid. The gel solution was cast on the membrane plastic plate to obtain membrane sheets. The dry membranes were then doped by immersing in various concentrations of KOH solutions for about 4 hours. Investigations of the cross-linking process and the presence of hydroxyl group were conducted by FTIR as shown for frequency at about 1600 cm{sup −1} and 3300 cm{sup −1} respectively. The degree of swelling in ethanol decreased as the KOH concentration for membrane soaking process increased. The ion exchange capacity (IEC) of the membrane was 0.25meq/g. This composite membranes display significant ionic conductivity of 3.23 x 10{sup −2} S/cm in deionized water at room temperature. In addition, the morphology observation by scanning electron microscope (SEM) of the membrane indicates that soaking process of membrane in KOH increased thermal resistant.

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

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

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

  6. Polybenzimidazole and sulfonated polyhedral oligosilsesquioxane composite membranes for high temperature polymer electrolyte membrane fuel cells

    DEFF Research Database (Denmark)

    Aili, David; Allward, Todd; Alfaro, Silvia Martinez;

    2014-01-01

    Composite membranes based on poly(2,2′(m-phenylene)-5,5́bibenzimidazole) (PBI) and sulfonated polyhedral oligosilsesquioxane (S-POSS) with S-POSS contents of 5 and 10wt.% were prepared by solution casting as base materials for high temperature polymer electrolyte membrane fuel cells. With membran...

  7. Development of composite membranes of PVA-TEOS doped KOH for alkaline membrane fuel cell

    Science.gov (United States)

    Haryadi, Sugianto, D.; Ristopan, E.

    2015-12-01

    Anion exchange membranes (AEMs) play an important role in separating fuel and oxygen (or air) in the Alkaline Membrane Fuel Cells. Preparation of hybrid organic inorganic materials of Polyvinylalcohol (PVA) - Tetraethylorthosilicate (TEOS) composite membrane doped KOH for direct alcohol alkaline fuel cell application has been investigated. The sol-gel method has been used to prepare the composite membrane of PVA-TEOS through crosslinking step and catalyzed by concentrated of hydrochloric acid. The gel solution was cast on the membrane plastic plate to obtain membrane sheets. The dry membranes were then doped by immersing in various concentrations of KOH solutions for about 4 hours. Investigations of the cross-linking process and the presence of hydroxyl group were conducted by FTIR as shown for frequency at about 1600 cm-1 and 3300 cm-1 respectively. The degree of swelling in ethanol decreased as the KOH concentration for membrane soaking process increased. The ion exchange capacity (IEC) of the membrane was 0.25meq/g. This composite membranes display significant ionic conductivity of 3.23 x 10-2 S/cm in deionized water at room temperature. In addition, the morphology observation by scanning electron microscope (SEM) of the membrane indicates that soaking process of membrane in KOH increased thermal resistant.

  8. Membrane for distillation including nanostructures, methods of making membranes, and methods of desalination and separation

    KAUST Repository

    Lai, Zhiping

    2016-01-21

    In accordance with the purpose(s) of the present disclosure, as embodied and broadly described herein, embodiments of the present disclosure provide membranes, methods of making the membrane, systems including the membrane, methods of separation, methods of desalination, and the like.

  9. Fuel cell and membrane therefore

    Energy Technology Data Exchange (ETDEWEB)

    Aindow, Tai-Tsui

    2016-08-09

    A fuel cell includes first and second flow field plates, and an anode electrode and a cathode electrode between the flow field plates. A polymer electrolyte membrane (PEM) is arranged between the electrodes. At least one of the flow field plates influences, at least in part, an in-plane anisotropic physical condition of the PEM that varies in magnitude between a high value direction and a low value direction. The PEM has an in-plane physical property that varies in magnitude between a high value direction and a low value direction. The PEM is oriented with its high value direction substantially aligned with the high value direction of the flow field plate.

  10. Catalyst containing oxygen transport membrane

    Science.gov (United States)

    Christie, Gervase Maxwell; Wilson, Jamie Robyn; van Hassel, Bart Antonie

    2012-12-04

    A composite oxygen transport membrane having a dense layer, a porous support layer and an intermediate porous layer located between the dense layer and the porous support layer. Both the dense layer and the intermediate porous layer are formed from an ionic conductive material to conduct oxygen ions and an electrically conductive material to conduct electrons. The porous support layer has a high permeability, high porosity, and a high average pore diameter and the intermediate porous layer has a lower permeability and lower pore diameter than the porous support layer. Catalyst particles selected to promote oxidation of a combustible substance are located in the intermediate porous layer and in the porous support adjacent to the intermediate porous layer. The catalyst particles can be formed by wicking a solution of catalyst precursors through the porous support toward the intermediate porous layer.

  11. Salt splitting with ceramic membranes

    Energy Technology Data Exchange (ETDEWEB)

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

    1996-10-01

    The purpose of this task is to develop ceramic membrane technologies for salt splitting of radioactively contaminated sodium salt solutions. This technology has the potential to reduce the low-level waste (LLW) disposal volume, the pH and sodium hydroxide content for subsequent processing steps, the sodium content of interstitial liquid in high-level waste (HLW) sludges, and provide sodium hydroxide free of aluminum for recycle within processing plants at the DOE complex. Potential deployment sites include Hanford, Savannah River, and Idaho National Engineering Laboratory (INEL). The technical approach consists of electrochemical separation of sodium ions from the salt solution using sodium (Na) Super Ion Conductors (NaSICON). As the name implies, sodium ions are transported rapidly through these ceramic crystals even at room temperatures.

  12. Water Transport through Multinanopores Membranes

    Institute of Scientific and Technical Information of China (English)

    ZENG Li; GUO Hong-Kai; ZUO Guang-Hong; WAN Rong-Zheng; FANG Hai-Ping

    2009-01-01

    We investigate the influence of correlation between water molecules transport through the neighbouring nanopores,whose centres are at a distance of only 6.2A,using the molecular dynamics simulations.Water molecule distribution in nanopore and average water flow are obtained.It is found that the average water molecule number and water flow are slightly different between a system made of the neighbouring nanopores and a system of a single pore.This indicates that transport of water chains in neighbouring pores do no show significant influence each other.These findings should be helpful in designing efficient artificial membrane made of nanopores and providing an insight into effects of the biological channel structure on the water permeation.

  13. 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...... 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...

  14. Development of functionalized nanostructured polymeric membranes for water purification

    OpenAIRE

    Altintas, Zeynep; Chianella, Iva; Da Ponte, Gabriella; Paulussen, Sabine; Gaeta, Soccorso; Tothill, Ibtisam E.

    2016-01-01

    Pharmaceuticals specific molecularly imprinted polymers nanoparticles (MIPNPs) were synthesized and applied onto the polyvinylidene fluoride (PVDF) membranes previously subjected to the plasma treatment. Diclofenac-, metoprolol- and vancomycin-MIPs were applied onto the membranes and scanning electron microscopy was employed to visualize MIPNPs on the membrane. After functionalization of the membranes with target-specific MIPs the molecularly imprinted membranes (MIMs) affinity against their ...

  15. Fatty acid profiles from the plasma membrane and detergent resistant membranes of two plant species.

    Science.gov (United States)

    Carmona-Salazar, Laura; El Hafidi, Mohammed; Gutiérrez-Nájera, Nora; Noyola-Martínez, Liliana; González-Solís, Ariadna; Gavilanes-Ruíz, Marina

    2015-01-01

    It is essential to establish the composition of the plant plasma membrane in order to understand its organization and behavior under continually changing environments. Knowledge of the lipid phase, in particular the fatty acid (FA) complex repertoire, is important since FAs determine many of the physical-chemical membrane properties. FAs are constituents of the membrane glycerolipid and sphingolipid backbones and can also be linked to some sterols. In addition, FAs are components of complex lipids that can constitute membrane micro-domains, and the use of detergent-resistant membranes is a common approach to study their composition. The diversity and cellular allocation of the membrane lipids containing FAs are very diverse and the approaches to analyze them provide only general information. In this work, a detailed FA analysis was performed using highly purified plasma membranes from bean leaves and germinating maize embryos and their respective detergent-resistant membrane preparations. The analyses showed the presence of a significant amount of very long chain FAs (containing 28C, 30C and 32C), in both plasma membrane preparations from bean and maize, that have not been previously reported. Herein is demonstrated that a significant enrichment of very long chain saturated FAs and saturated FAs can occur in detergent-resistant membrane preparations, as compared to the plasma membranes from both plant species. Considering that a thorough analysis of FAs is rarely performed in purified plasma membranes and detergent-resistant membranes, this work provides qualitative and quantitative evidence on the contributions of the length and saturation of FAs to the organization of the plant plasma membrane and detergent-resistant membranes.

  16. Biomimetic polymeric membranes for water treatment

    DEFF Research Database (Denmark)

    Habel, Joachim Erich Otto

    of the proteopolymersomes. The modest membrane performance of all membranes revealed however defects in the AL, which could be due to the micrometer sized pores of PES. ABPMs could provide a smart solution to one of the worlds greatest challenges in the next decades: the scarcity of clean water and sanitation access....

  17. Proton conducting membrane for fuel cells

    Science.gov (United States)

    Colombo, Daniel G.; Krumpelt, Michael; Myers, Deborah J.; Kopasz, John P.

    2007-03-27

    An ion conducting membrane comprising dendrimeric polymers covalently linked into a network structure. The dendrimeric polymers have acid functional terminal groups and may be covalently linked via linking compounds, cross-coupling reactions, or copolymerization reactions. The ion conducting membranes may be produced by various methods and used in fuel cells.

  18. Interactions between Janus particles and membranes

    Science.gov (United States)

    Ding, Hong-Ming; Ma, Yu-Qiang

    2012-02-01

    Understanding how nanoparticles interact with cell membranes is of great importance in drug/gene delivery. In this paper, we investigate the interactions between Janus particles and membranes by using dissipative particle dynamics, and find that there exist two different modes (i.e., insertion and engulfment) in the Janus particle-membrane interactions. The initial orientation and properties of Janus particles have an important impact on the interactions. When the hydrophilic part of the particle is close to the membrane or the particle has a larger section area and higher hydrophilic coverage, the particle is more likely to be engulfed by the membrane. We also provide insights into the interactions between Janus particles and membranes containing lipid rafts, and find that a Janus particle could easily detach from a membrane after it is engulfed by the raft. The present study suggests a potential way to translocate Janus particles through membranes, which may give some significant suggestions on future nanoparticle design for drug delivery.

  19. HIGH PERFORMANCE CERIA BASED OXYGEN MEMBRANE

    DEFF Research Database (Denmark)

    2014-01-01

    -dopant have an ionic size ratio between 0.5 and 1. These materials can thereby improve the performance and extend the range of operating conditions of oxygen permeation membranes (OPM) for different high temperature membrane reactor applications. The invention also relates to the manufacturing of supported...

  20. Inflation and Instability of a Polymeric Membrane

    DEFF Research Database (Denmark)

    Neergaard, Jesper; Hassager, Ole

    1999-01-01

    -Pearson condition.Molecularly based models such as the neo-Hookean, Doi-Edwards or Tom-Pom model exhibit a pressure maximum when inflated. Membranes described by these models develop local thinning which may lead to bursting in finite time. Chain branching is found to be a stabilizing factor for a polymer membrane...

  1. Electrodiffusion of lipids on membrane surfaces

    Science.gov (United States)

    Zhou, Y. C.

    2012-05-01

    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 the random lateral motion is mediated by the electrostatic interactions and membrane curvature. Although the lateral diffusion rates of lipids on membranes of various compositions are measured and the electrostatic free energies of predetermined protein-membrane-lipid systems can be computed, the process of the aggregation and the evolution to the electrostatically favorable states remain largely undetermined. Here we propose an electrodiffusion model, based on the variational principle of the free energy functional, for the self-consistent lateral drift-diffusion of multiple species of charged lipids on membrane surfaces. Finite sizes of lipids are modeled to enforce the geometrical constraint of the lipid concentration on membrane surfaces. A surface finite element method is developed to appropriate the Laplace-Beltrami operators in the partial differential equations of the model. Our model properly describes the saturation of lipids on membrane surfaces, and correctly predicts that the MARCKS peptide can consistently sequester three multivalent phosphatidylinositol 4,5-bisphosphate lipids through its basic amino acid residues, regardless of a wide range of the percentage of monovalent phosphatidylserine in the membrane.

  2. Kinetics and Thermodynamics of Membrane Protein Folding

    Directory of Open Access Journals (Sweden)

    Ernesto A. Roman

    2014-03-01

    Full Text Available Understanding protein folding has been one of the great challenges in biochemistry and molecular biophysics. Over the past 50 years, many thermodynamic and kinetic studies have been performed addressing the stability of globular proteins. In comparison, advances in the membrane protein folding field lag far behind. Although membrane proteins constitute about a third of the proteins encoded in known genomes, stability studies on membrane proteins have been impaired due to experimental limitations. Furthermore, no systematic experimental strategies are available for folding these biomolecules in vitro. Common denaturing agents such as chaotropes usually do not work on helical membrane proteins, and ionic detergents have been successful denaturants only in few cases. Refolding a membrane protein seems to be a craftsman work, which is relatively straightforward for transmembrane β-barrel proteins but challenging for α-helical membrane proteins. Additional complexities emerge in multidomain membrane proteins, data interpretation being one of the most critical. In this review, we will describe some recent efforts in understanding the folding mechanism of membrane proteins that have been reversibly refolded allowing both thermodynamic and kinetic analysis. This information will be discussed in the context of current paradigms in the protein folding field.

  3. Characterization of fouling of membrane contactors

    DEFF Research Database (Denmark)

    Ciurkot, Kaludia; Zarebska, Agata; Christensen, Knud Villy

    2013-01-01

    In this study liquid-liquid membrane contactors have been tested for ammonia removal from model manure solution and undigested pig manure. The aim of this work is to compare the efficiency of ammonia removal by different hydrophobic membranes including the material’s influence on mass transfer...

  4. Polyene antibiotic that inhibits membrane transport proteins.

    Science.gov (United States)

    te Welscher, Yvonne Maria; van Leeuwen, Martin Richard; de Kruijff, Ben; Dijksterhuis, Jan; Breukink, Eefjan

    2012-07-10

    The limited therapeutic arsenal and the increase in reports of fungal resistance to multiple antifungal agents have made fungal infections a major therapeutic challenge. The polyene antibiotics are the only group of antifungal antibiotics that directly target the plasma membrane via a specific interaction with the main fungal sterol, ergosterol, often resulting in membrane permeabilization. In contrast to other polyene antibiotics that form pores in the membrane, the mode of action of natamycin has remained obscure but is not related to membrane permeabilization. Here, we demonstrate that natamycin inhibits growth of yeasts and fungi via the immediate inhibition of amino acid and glucose transport across the plasma membrane. This is attributable to ergosterol-specific and reversible inhibition of membrane transport proteins. It is proposed that ergosterol-dependent inhibition of membrane proteins is a general mode of action of all the polyene antibiotics, of which some have been shown additionally to permeabilize the plasma membrane. Our results imply that sterol-protein interactions are fundamentally important for protein function even for those proteins that are not known to reside in sterol-rich domains. PMID:22733749

  5. Dense ceramic membranes for methane conversion

    NARCIS (Netherlands)

    Bouwmeester, Henny J.M.

    2003-01-01

    Dense ceramic membranes made from mixed oxygen-ionic and electronic conducting perovskite-related oxides allow separation of oxygen from an air supply at elevated temperatures (>700 °C). By combining air separation and catalytic partial oxidation of methane to syngas into a ceramic membrane reactor,

  6. Tubular Membrane Plant-Growth Unit

    Science.gov (United States)

    Dreschel, Thomas W.

    1992-01-01

    Hydroponic system controls nutrient solution for growing crops in space. Pump draws nutrient solution along inside of tubular membrane in pipe from reservoir, maintaining negative pressure in pipe. Roots of plants in slot extract nutrient through membrane within pipe. Crop plants such as wheat, rice, lettuce, tomatoes, soybeans, and beans grown successfully with system.

  7. Preparation of Electrically Conductive Polymeric Membranes

    Science.gov (United States)

    Encinas, J. C.; Castillo-Ortega, M. M.; Rodríguez, F.; Castaño, V. M.

    2015-10-01

    Cellulose acetate porous membranes, coated with polyaniline, were chemically modified with polyelectrolytes to produce films of varying and controlled porosity and electrical conductivity. The highest electrical conductivity was obtained in membranes prepared with poly(styrene sulfonate) with large pore sizes. The electrical properties as well as scanning electron microscopy (SEM) images are discussed.

  8. Metal doped hybrid silica membranes for separation

    NARCIS (Netherlands)

    Ru, Yanfei

    2014-01-01

    The present study describes the e ect of di erent factors such as the type of dopants and the percentage of dopants on the stability and permeance of membranes. Di erent dopants such as zirconia, yttrium were used to produce organic-inorganic hybrid silica membranes. During the programme, zirconia d

  9. Black Hole Complementary Principle and Noncommutative Membrane

    International Nuclear Information System (INIS)

    In the spirit of black hole complementary principle, we have found the noncommutative membrane of Scharzchild black holes. In this paper we extend our results to Kerr black hole and see the same story. Also we make a conjecture that spacetimes are noncommutative on the stretched membrane of the more general Kerr-Newman black hole.

  10. NITROGEN-SELECTIVE MEMBRANE FOR CARBON CAPTURE

    Science.gov (United States)

    Dense membrane technology will be tested and applied under conditions that optimize the separation of N2 from CO2 from post-combustion flue gas. This membrane technology will help in retrofitting existing coal-fired power plants so as to comply with emission regulations.

  11. Diffuse Charge Effects in Fuel Cell Membranes

    NARCIS (Netherlands)

    Biesheuvel, P.M.; Franco, A.A.; Bazant, M.Z.

    2009-01-01

    It is commonly assumed that electrolyte membranes in fuel cells are electrically neutral, except in unsteady situations, when the double-layer capacitance is heuristically included in equivalent circuit calculations. Indeed, the standard model for electron transfer kinetics at the membrane/electrode

  12. Tandem Facial Amphiphiles for Membrane Protein Stabilization

    DEFF Research Database (Denmark)

    Chae, Pil Seok; Gotfryd, Kamil; Pacyna, Jennifer;

    2010-01-01

    We describe a new type of synthetic amphiphile that is intended to support biochemical characterization of intrinsic membrane proteins. Members of this new family displayed favorable behavior with four of five membrane proteins tested, and these amphiphiles formed relatively small micelles....

  13. Tubular Steel Arch Stabilized by Textile Membranes

    Directory of Open Access Journals (Sweden)

    Ondrej Svoboda

    2016-10-01

    Full Text Available Tubular steel arch supporting textile membrane roofing is investigated experimentally and numerically. The stabilization effects of the textile membrane on in-plane and out-of-plane behavior of the arch is of primary interest. First a model of a large membrane structure tested in laboratory is described. Prestressed membranes of PVC coated polyester fabric Ferrari® Précontraint 702S were used as a currently standard and excellent material. The test arrangement, loading and resulting load/deflection values are presented. The supporting structure consisted of two steel arch tubes, outer at edge of the membrane and inner supporting interior of the membrane roofing. The stability and strength behavior of the inner tube under both symmetrical and asymmetrical loading was monitored and is shown in some details. Second the SOFiSTiK software was employed to analyze the structural behavior in 3D, using geometrically nonlinear analysis with imperfections (GNIA. The numerical analysis, FE mesh sensitivity, the membrane prestressing and common boundary conditions are validated by test results. Finally a parametrical study concerning stability of mid arch with various geometries in a membrane structure with several supporting arches is presented, with recommendations for a practical design.

  14. 2010 Membranes: Materials & Processes Gordon Research Conference

    Energy Technology Data Exchange (ETDEWEB)

    Jerry Lin

    2010-07-30

    The GRC series on Membranes: Materials and Processes have gained significant international recognition, attracting leading experts on membranes and other related areas from around the world. It is now known for being an interdisciplinary and synergistic meeting. The next summer's edition will keep with the past tradition and include new, exciting aspects of material science, chemistry, chemical engineering, computer simulation with participants from academia, industry and national laboratories. This edition will focus on cutting edge topics of membranes for addressing several grand challenges facing our society, in particular, energy, water, health and more generally sustainability. During the technical program, we want to discuss new membrane structure and characterization techniques, the role of advanced membranes and membrane-based processes in sustainability/environment (including carbon dioxide capture), membranes in water processes, and membranes for biological and life support applications. As usual, the informal nature of the meeting, excellent quality of the oral presentations and posters, and ample opportunity to meet many outstanding colleagues make this an excellent conference for established scientists as well as for students. A Gordon Research Seminar (GRS) on the weekend prior to the GRC meeting will provide young researchers an opportunity to present their work and network with outstanding experts. It will also be a right warm-up for the conference participants to join and enjoy the main conference.

  15. Inflation and Instability of a Polymeric Membrane

    DEFF Research Database (Denmark)

    Neergaard, Jesper; Hassager, Ole

    1999-01-01

    -Rivlin model show a monotone increasingpressure during inflation of a spherical membrane. These materials develop a homogeneous membrane thickness in agreement with the Considere-Pearson condition. Molecularly based models such as the neo-Hookean, Doi-Edwards or Tom-Pom model show a pressure maximum when...

  16. Stringy Membranes in AdS/CFT

    CERN Document Server

    Axenides, Minos; Linardopoulos, Georgios

    2013-01-01

    We study membrane configurations in AdS_{7/4}xS^{4/7}. The membranes are wrapped around the compact manifold S^{4/7} and are dynamically equivalent to bosonic strings in AdS_5. We thus conveniently identify them as "stringy membranes". For the case of AdS_7xS^4, their construction is carried out by embedding the Polyakov action for classical bosonic strings in AdS_5, into the corresponding membrane action. Therefore, every string configuration in AdS_5 can be realized by an appropriately chosen stringy membrane in AdS_7xS^4. We discuss the possibility of this being also the case for stringy membranes in AdS_4xS^7/Z^k (k > 1 or k = 1). By performing a stability analysis to the constructed solutions, we find that the (membrane) fluctuations along their transverse directions are organized in multiple Lam\\'{e} stability bands and gaps in the space of parameters of the configurations. In this membrane picture, strings exhibit a single band/gap structure. Since the spectrum of quadratic fluctuations is important fo...

  17. Lipid Acrobatics in the Membrane Fusion Arena

    NARCIS (Netherlands)

    Markvoort, Albert J.; Marrink, Siewert J.; Chernomordik, Leonid V.; Kozlov, Michael M.

    2011-01-01

    In this review, we describe the recent contribution of computer simulation approaches to unravel the molecular details of membrane fusion. Over the past decade, fusion between apposed membranes and vesicles has been studied using a large variety of simulation methods and systems. Despite the variety

  18. Nuclear magnetic resonance studies of erythrocyte membranes

    NARCIS (Netherlands)

    Chapman, D.; Kamat, V.B.; Gier, J. de; Penkett, S.A.

    1968-01-01

    The use of nuclear magnetic resonance spectroscopy for studying molecular interactions in biological membranes has been investigated using erythrocyte membrane fragments. Sonic dispersion of these fragments produces a sharp and well-defined high-resolution nuclear magnetic resonance spectrum. The sp

  19. Active Nuclear Import of Membrane Proteins Revisited

    NARCIS (Netherlands)

    Laba, Justyna K; Steen, Anton; Popken, Petra; Chernova, Alina; Poolman, Bert; Veenhoff, Liesbeth M

    2015-01-01

    It is poorly understood how membrane proteins destined for the inner nuclear membrane pass the crowded environment of the Nuclear Pore Complex (NPC). For the Saccharomyces cerevisiae proteins Src1/Heh1 and Heh2, a transport mechanism was proposed where the transmembrane domains diffuse through the m

  20. Sperm Membrane Behaviour during Cooling and Cryopreservation.

    Science.gov (United States)

    Sieme, H; Oldenhof, H; Wolkers, W F

    2015-09-01

    Native sperm is only marginally stable after collection. Cryopreservation of semen facilitates transport and storage for later use in artificial reproduction technologies, but cryopreservation processing may result in cellular damage compromising sperm function. Membranes are thought to be the primary site of cryopreservation injury. Therefore, insights into the effects of cooling, ice formation and protective agents on sperm membranes may help to rationally design cryopreservation protocols. In this review, we describe membrane phase behaviour of sperm at supra- and subzero temperatures. In addition, factors affecting membrane phase transitions and stability, sperm osmotic tolerance limits and mode of action of cryoprotective agents are discussed. It is shown how cooling only results in minor thermotropic non-cooperative phase transitions, whereas freezing causes sharp lyotropic fluid-to-gel phase transitions. Membrane cholesterol content affects suprazero membrane phase behaviour and osmotic tolerance. The rate and extent of cellular dehydration coinciding with freezing-induced membrane phase transitions are affected by the cooling rate and ice nucleation temperature and can be modulated by cryoprotective agents. Permeating agents such as glycerol can move across cellular membranes, whereas non-permeating agents such as sucrose cannot. Both, permeating and non-permeating protectants preserve biomolecular and cellular structures by forming a protective glassy state during freezing. PMID:26382025

  1. Inflation and Instability of a Polymeric Membrane

    DEFF Research Database (Denmark)

    Hassager, Ole; Kristensen, Susanne Brogaard; Larsen, Johannes Ruben;

    1999-01-01

    -Rivlin model show a monotone increasing pressure during inflation of a spherical membrane. These materials develop a homogeneous membrane thickness in agreement with the Considere-Pearson condition. Molecularly based models such as the neo-Hookean, Doi-Edwards or Tom-Pom model show a pressure maximum when...

  2. Transport and sorting of membrane lipids

    NARCIS (Netherlands)

    van Meer, G.

    1993-01-01

    The lipid composition of cellular membranes may seem unnecessarily complex. However, the lipid composition of each membrane is carefully regulated by local metabolism and specificity in transport, marking the functional significance for the cell. Recent research has revealed unexpected discoveries c

  3. Zein Recovery Using Non-Porous Membranes

    Science.gov (United States)

    Mairal, Anurag P.; Ng, Alvin; Wijmans, Johannes G.

    2005-01-25

    A membrane process for treating zein solutions to increase the zein concentration in the solution. The process uses a non-porous membrane that preferentially permeates the solvent and rejects the zein. Optionally, the process can be operated as a diafiltration process to yield a concentrate of high zein purity.

  4. Membrane lipidome of an epithelial cell line

    DEFF Research Database (Denmark)

    Sampaio, Julio L; Gerl, Mathias J; Klose, Christian;

    2011-01-01

    Tissue differentiation is an important process that involves major cellular membrane remodeling. We used Madin-Darby canine kidney cells as a model for epithelium formation and investigated the remodeling of the total cell membrane lipidome during the transition from a nonpolarized morphology...

  5. Reactive membrane technology: Two case studies

    DEFF Research Database (Denmark)

    Zeuner, Birgitte; Luo, Jianquan; Pinelo, Manuel;

    2014-01-01

    Enzymatic processes are generally sustainable processes that use mild conditions and natural substrates. Membrane technology can be employed for enzyme immobilization as well as for recycling free enzymes. Using alcohol dehydrogenase (ADH) as part of a process to recycle CO2 to methanol, we inves...... in an enzymatic membrane reactor. The entire process can be improved by employing a series of ultra- and nanofiltrations....

  6. A STUDY ON MEMBRANE PROCESS WITH γ-ALUMINA MEMBRANE REACTOR FOR ETHYLBENZENE DEHYDROGENATION TO STYRENE

    Institute of Scientific and Technical Information of China (English)

    Chen Qingling; Xu Zhongqiang

    2001-01-01

    The membrane reaction of ethylbenzene(EB) dehydrogenation to styrene(ST) has been studied by using K2O/Fe2O3 industrial catalyst and γ-alumina ceramic membrane developed by our institute. In comparison with the packed bed reactor (that is, plug flow reactor, abbr. PFR) in industrial practice, the yield of styrene was increased by 5%~10% in the membrane reactor. Furthermore, mathematical modeling of membrane reaction has been studied to display the principle of optimal match between the catalytic activity and the membrane permeability.

  7. A Quaternary Polybenzimidazole Membrane for Intermediate Temperature Polymer Electrolyte Membrane Fuel Cells

    DEFF Research Database (Denmark)

    Xu, C.; Scott, K.; Li, Qingfeng;

    2013-01-01

    A quaternary ammonium polybenzimidazole (QPBI) membrane was synthesized for applications in intermediate temperature (100–200 °C) hydrogen fuel cells. The QPBI membrane was imbibed with phosphoric acid to provide suitable proton conductivity. The proton conductivity of the membrane was 0.051 S cm–1...... at 150 °C with the PA acid loading level of 3.5 PRU (amount of H3PO4 per repeat unit of polymer QPBI). The QPBI membrane was characterized in terms of composition, structure and morphology by NMR, FTIR, SEM, and EDX. The fuel cell performance with the membrane gave peak power densities of 440 and 240 m...

  8. Modelling and Simulations of Multi-component Lipid Membranes and Open Membranes via Diffusive Interface Approaches

    CERN Document Server

    Wang, X; Wang, Xiaoqiang; Du, Qiang

    2006-01-01

    In this paper, phase field models are developed for multi-component vesicle membranes with different lipid compositions and membranes with free boundary. These models are used to simulate the deformation of membranes under the elastic bending energy and the line tension energy with prescribed volume and surface area constraints. By comparing our numerical simulations with recent experiments, it is demonstrated that the phase field models can capture the rich phenomena associated with the membrane transformation, thus it offers great functionality in the simulation and modeling of multicomponent membranes.

  9. POLYETHERSULFONE COMPOSITE MEMBRANE BLENDED WITH CELLULOSE FIBRILS

    Directory of Open Access Journals (Sweden)

    Ping Qu

    2010-09-01

    Full Text Available Polyethersulfone (PES is a common material used for ultrafiltration (UF membranes, which has good chemical resistance, high mechanical properties, and wide temperature tolerances. The hydrophobic property of the PES membrane seriously limits its application. Cellulose fibrils are composed of micro-sized and nano-sized elements, which have high hydrophilicity, strength, and biodegradation. A composite membrane was prepared by the phase inversion induced by an immersion process. The characteristics of the composite membrane were investigated with Fourier transform infrared spectroscopy (FTIR, X-ray diffraction (XRD, thermogravimetric analysis (TGA, and atomic force microscopy (AFM. The pure water flux of the composite membrane increased dramatically with the increase of cellulose firbils. Mean pore size and porosity were significantly increased. Both mechanical properties and hydrophilicity were enhanced due to the addition of the cellulose firbils.

  10. Optimal operation of batch membrane processes

    CERN Document Server

    Paulen, Radoslav

    2016-01-01

    This study concentrates on a general optimization of a particular class of membrane separation processes: those involving batch diafiltration. Existing practices are explained and operational improvements based on optimal control theory are suggested. The first part of the book introduces the theory of membrane processes, optimal control and dynamic optimization. Separation problems are defined and mathematical models of batch membrane processes derived. The control theory focuses on problems of dynamic optimization from a chemical-engineering point of view. Analytical and numerical methods that can be exploited to treat problems of optimal control for membrane processes are described. The second part of the text builds on this theoretical basis to establish solutions for membrane models of increasing complexity. Each chapter starts with a derivation of optimal operation and continues with case studies exemplifying various aspects of the control problems under consideration. The authors work their way from th...

  11. Molecular simulation of nonfacilitated membrane permeation.

    Science.gov (United States)

    Awoonor-Williams, Ernest; Rowley, Christopher N

    2016-07-01

    This is a review. Non-electrolytic compounds typically cross cell membranes by passive diffusion. The rate of permeation is dependent on the chemical properties of the solute and the composition of the lipid bilayer membrane. Predicting the permeability coefficient of a solute is important in pharmaceutical chemistry and toxicology. Molecular simulation has proven to be a valuable tool for modeling permeation of solutes through a lipid bilayer. In particular, the solubility-diffusion model has allowed for the quantitative calculation of permeability coefficients. The underlying theory and computational methods used to calculate membrane permeability are reviewed. We also discuss applications of these methods to examine the permeability of solutes and the effect of membrane composition on permeability. The application of coarse grain and polarizable models is discussed. This article is part of a Special Issue entitled: Membrane Proteins edited by J.C. Gumbart and Sergei Noskov. PMID:26706099

  12. Ionomer-Membrane Water Processing Apparatus

    Science.gov (United States)

    MacCallum, Taber K. (Inventor); Kelsey, Laura (Inventor)

    2016-01-01

    This disclosure provides water processing apparatuses, systems, and methods for recovering water from wastewater such as urine. The water processing apparatuses, systems, and methods can utilize membrane technology for extracting purified water in a single step. A containment unit can include an ionomer membrane, such as Nafion(Registered Trademark), over a hydrophobic microporous membrane, such as polytetrafluoroethylene (PTFE). The containment unit can be filled with wastewater, and the hydrophobic microporous membrane can be impermeable to liquids and solids of the wastewater but permeable to gases and vapors of the wastewater, and the ionomer membrane can be permeable to water vapor but impermeable to one or more contaminants of the gases and vapors. The containment unit can be exposed to a dry purge gas to maintain a water vapor partial pressure differential to drive permeation of the water vapor, and the water vapor can be collected and processed into potable water.

  13. Carbon Nanotube-Based Permeable Membranes

    Energy Technology Data Exchange (ETDEWEB)

    Holt, J K; Park, H G; Bakajin, O; Noy, A; Huser, T; Eaglesham, D

    2004-04-06

    A membrane of multiwalled carbon nanotubes embedded in a silicon nitride matrix was fabricated for use in studying fluid mechanics on the nanometer scale. Characterization by fluorescent tracer diffusion and scanning electron microscopy suggests that the membrane is void-free near the silicon substrate on which it rests, implying that the hollow core of the nanotube is the only conduction path for molecular transport. Assuming Knudsen diffusion through this nanotube membrane, a maximum helium transport rate (for a pressure drop of 1 atm) of 0.25 cc/sec is predicted. Helium flow measurements of a nanoporous silicon nitride membrane, fabricated by sacrificial removal of carbon, give a flow rate greater than 1x10{sup -6} cc/sec. For viscous, laminar flow conditions, water is estimated to flow across the nanotube membrane (under a 1 atm pressure drop) at up to 2.8x10{sup -5} cc/sec (1.7 {micro}L/min).

  14. Anisotropic Membrane Curvature Sensing by Amphipathic Peptides.

    Science.gov (United States)

    Gómez-Llobregat, Jordi; Elías-Wolff, Federico; Lindén, Martin

    2016-01-01

    Many proteins and peptides have an intrinsic capacity to sense and induce membrane curvature, and play crucial roles for organizing and remodeling cell membranes. However, the molecular driving forces behind these processes are not well understood. Here, we describe an approach to study curvature sensing by simulating the interactions of single molecules with a buckled lipid bilayer. We analyze three amphipathic antimicrobial peptides, a class of membrane-associated molecules that specifically target and destabilize bacterial membranes, and find qualitatively different sensing characteristics that would be difficult to resolve with other methods. Our findings provide evidence for direction-dependent curvature sensing mechanisms in amphipathic peptides and challenge existing theories of hydrophobic insertion. The buckling approach is generally applicable to a wide range of curvature-sensing molecules, and our results provide strong motivation to develop new experimental methods to track position and orientation of membrane proteins. PMID:26745422

  15. Membrane barriers for radon gas flow restrictions

    International Nuclear Information System (INIS)

    Research was performed to assess the feasibility of barrier membrane substances, for use within mining or associated high risk environments, in restricting the diffusion transport of radon gas quantities. Specific tests were conducted to determine permeability parameters of a variety of membrane materials with reference to radon flow capabilities. Tests were conducted both within laboratory and in-situ emanation environments where concentrations and diffusion flows of radon gas were known to exist. Equilibrium radon gas concentrations were monitored in initially radon-free chambers adjacent to gas sources, but separated by specified membrane substances. Membrane barrier effectiveness was demonstrated to result in reduced emanation concentrations of radon gas within the sampling chamber atmosphere. Minimum gas concentrations were evidenced where the barrier membrane material was shown to exhibit lowest radon permeability characteristics

  16. Proton conducting ceramic membranes for hydrogen separation

    Science.gov (United States)

    Elangovan, S.; Nair, Balakrishnan G.; Small, Troy; Heck, Brian

    2011-09-06

    A multi-phase proton conducting material comprising a proton-conducting ceramic phase and a stabilizing ceramic phase. Under the presence of a partial pressure gradient of hydrogen across the membrane or under the influence of an electrical potential, a membrane fabricated with this material selectively transports hydrogen ions through the proton conducting phase, which results in ultrahigh purity hydrogen permeation through the membrane. The stabilizing ceramic phase may be substantially structurally and chemically identical to at least one product of a reaction between the proton conducting phase and at least one expected gas under operating conditions of a membrane fabricated using the material. In a barium cerate-based proton conducting membrane, one stabilizing phase is ceria.

  17. Investigation of organic fouling of microfiltration membrane

    Institute of Scientific and Technical Information of China (English)

    XIAO Feng; CUI Chong-wei; MA Jun

    2005-01-01

    Because the natural organic matters (NOMs) and proteins are the principal foulants of microfiltration membranes in drinking water, the primary aim of this paper is to obtain a better understanding of the interactions between those foulants and the microfiltration membrane from a novel view of coagulation. Based on reviewed literature and our own analysis, the authors consider that the behaviors of NOMs in the fouling of microfiltration membrane are like a form of crystal growth, and we recognize that the extent of the membrane hydrophobicity plays an essential role in NOMs fouling. However, proteins' fouling is more affected by intermolecular interaction. Additionally, the effect of membrane surface chemistry is not as essential as it is in the situation of NOMs.

  18. Liners for ion transport membrane systems

    Science.gov (United States)

    Carolan, Michael Francis; Miller, Christopher Francis

    2010-08-10

    Ion transport membrane system comprising (a) a pressure vessel comprising an interior, an exterior, an inlet, an inlet conduit, an outlet, and an outlet conduit; (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 the inlet and the outlet of the pressure vessel are in flow communication with exterior regions of the membrane modules; (c) a gas manifold having an interior surface wherein the gas manifold is in flow communication with the interior region of each of the planar ion transport membrane modules and with the exterior of the pressure vessel; and (d) a liner disposed within any of the inlet conduit, the outlet conduit, and the interior surface of the gas manifold.

  19. Methods of making membrane electrode assemblies

    Science.gov (United States)

    Kim, Yu Seung; Lee, Kwan -Soo; Rockward, Tommy Q. T.

    2015-07-28

    Method of making a membrane electrode assembly comprising: providing a membrane comprising a perfluorinated sulfonic acid; providing a first transfer substrate; applying to a surface of the first transfer substrate a first ink, said first ink comprising an ionomer and a catalyst; applying to the first ink a suitable non-aqueous swelling agent; forming an assembly comprising: the membrane; and the first transfer substrate, wherein the surface of the first transfer substrate comprising the first ink and the non-aqueous swelling agent is disposed upon one surface of the membrane; and heating the assembly at a temperature of 150.degree. C. or less and at a pressure of from about 250 kPa to about 3000 kPa or less for a time suitable to allow substantially complete transfer of the first ink and the second ink to the membrane; and cooling the assembly to room temperature and removing the first transfer substrate and the second transfer substrate.

  20. Vitreous membranes used in the biogas purification

    International Nuclear Information System (INIS)

    In the present work 10 vitreous membranes with different masses of zinc oxide (ZnO(s)) and particle diameters charcoal (DPC) are used in the purification of biogas. The porosity and tortuosity of the membranes is obtained, showing the variation with respect to the composition thereof. From these structural features specific flow of H2S(g) is obtained which is transferred using the Fick's diffusion equation in the membranes and its value increases with increasing mass of ZnO(s). By X-ray diffraction membrane made with 3.16 g of ZnO(s) forming zinc sulfide it is shown, so we can say that the removal of H2S(g) occurs by a process of absorption with chemical reaction in the membranes. (Author)