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Sample records for internal limiting membrane

  1. Effects of internal limiting membrane peeling during vitrectomy for macula-off primary rhegmatogenous retinal detachment.

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    Blanco-Teijeiro, María José; Bande Rodriguez, Manuel; Mansilla Cuñarro, Raquel; Paniagua Fernández, Laura; Ruiz-Oliva Ruiz, Francisco; Piñeiro Ces, Antonio

    2018-03-01

    To determine the effectiveness of internal limiting membrane peeling during vitrectomy for macula-off primary rhegmatogenous retinal detachment in the prevention of postoperative epiretinal membrane formation and achievement of good visual outcomes and to identify preoperative and intraoperative risk factors for epiretinal membrane formation. We retrospectively analyzed data from 62 eyes of 62 consecutive patients with macula-off primary rhegmatogenous retinal detachment who underwent vitrectomy with (n = 30) or without (n = 32) internal limiting membrane peeling between January 2014 and March 2016 and were followed up for at least 12 months. The effects of internal limiting membrane peeling on visual outcomes and postoperative recovery of the macular structure were determined. We subsequently divided patients into an epiretinal membrane group and a non-epiretinal membrane group and assessed the effects of various preoperative and intraoperative factors on postoperative epiretinal membrane formation. Postoperative epiretinal membrane developed in 10 patients in the no internal limiting membrane peeling group and three patients in the internal limiting membrane peeling group. Postoperative visual acuity significantly improved in both groups. Epiretinal membrane formation was found to be correlated with a higher number of retinal breaks. Our results suggest that internal limiting membrane peeling during macula-off primary rhegmatogenous retinal detachment surgery can reduce the occurrence of postoperative epiretinal membrane, is safe, and results in favorable visual outcomes.

  2. Multiple extrafoveal macular holes following internal limiting membrane peeling

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    Hussain N

    2018-05-01

    Full Text Available Nazimul Hussain, Sandip Mitra Department of Ophthalmology, Al Zahra Hospital, Sharjah, United Arab Emirates Objective: Internal limiting membrane (ILM peeling has been the standard of treatment for macular holes. Besides, causing retinal nerve fiber layer surface abnormality, postoperative extrafoveal multiple retinal holes is a rare phenomenon following ILM peeling. We report an unusual complication of eight extrafoveal macular holes occurring following ILM peeling.Case presentation: A 60-year-old male presented with complaints of decreased and distorted vision in the right eye. He was diagnosed as having epiretinal membrane with lamellar macular hole. He underwent 23G pars plana vitrectomy, brilliant blue assisted ILM peeling and fluid gas exchange. Intraoperatively, ILM was found to be adherent to the underlying neurosensory retina. One month after cataract surgery, he underwent YAG capsulotomy in the right eye. He complained of visual distortion. His fundus evaluation in the right eye showed multiple (eight extrafoveal retinal holes temporal to the macula clustered together.Conclusion: This case demonstrated that peeling of ILM, especially when it is adherent to the underlying neurosensory retina, may cause unwanted mechanical trauma to the inner retina. Glial apoptosis and neuronal degeneration may presumably play a role in delayed appearance of multiple (eight extrafoveal macular holes, which has not been reported earlier. Keywords: internal limiting membrane, lamellar macular hole, full thickness macular holes, epiretinal membrane

  3. DETRIMENTAL EFFECTS OF ACTIVE INTERNAL LIMITING MEMBRANE PEELING DURING EPIRETINAL MEMBRANE SURGERY: Microperimetric Analysis.

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    Deltour, Jean-Baptiste; Grimbert, Pierre; Masse, Helene; Lebreton, Olivier; Weber, Michel

    2017-03-01

    The aim of the study was to assess the microperimetric consequences of active internal limiting membrane (ILM) peeling during idiopathic epimacular membrane (IEMM) surgery. This retrospective monocentric study included 32 eyes of 31 consecutive patients who underwent IEMM surgery. Internal limiting membrane integrity was assessed by ILM Blue staining after IEMM removal: peeling was spontaneous (Group S) or active (Group A). Preprocedure and postprocedure (1 and 6 months) examinations were performed using visual acuity determination, spectral domain optical coherence tomography and microperimetry. Twenty-two eyes had an "active ILM peeling" and 10 a "spontaneous ILM peeling." Both groups had comparable and significant improvements in visual acuity 6 months after surgery (+1.82 lines [+9 letters] [Group A] and +1.51 lines [+8 letters] [Group S], P peeling has progressively become generalized in IEMM surgery to reduce recurrences. This additional procedure does not change the postoperative visual acuity but increases the development of deeper microscotomas. The real impact on the quality of vision remains unclear. Active ILM peeling in IEMM surgery may be responsible for visual impairment related to its microtraumatic effects.

  4. Increase in average foveal thickness after internal limiting membrane peeling

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    Kumagai K

    2017-04-01

    Full Text Available Kazuyuki Kumagai,1 Mariko Furukawa,1 Tetsuyuki Suetsugu,1 Nobuchika Ogino2 1Department of Ophthalmology, Kami-iida Daiichi General Hospital, 2Department of Ophthalmology, Nishigaki Eye Clinic, Aichi, Japan Purpose: To report the findings in three cases in which the average foveal thickness was increased after a thin epiretinal membrane (ERM was removed by vitrectomy with internal limiting membrane (ILM peeling.Methods: The foveal contour was normal preoperatively in all eyes. All cases underwent successful phacovitrectomy with ILM peeling for a thin ERM. The optical coherence tomography (OCT images were examined before and after the surgery. The changes in the average foveal (1 mm thickness and the foveal areas within 500 µm from the foveal center were measured. The postoperative changes in the inner and outer retinal areas determined from the cross-sectional OCT images were analyzed.Results: The average foveal thickness and the inner and outer foveal areas increased significantly after the surgery in each of the three cases. The percentage increase in the average foveal thickness relative to the baseline thickness was 26% in Case 1, 29% in Case 2, and 31% in Case 3. The percentage increase in the foveal inner retinal area was 71% in Case 1, 113% in Case 2, and 110% in Case 3, and the percentage increase in foveal outer retinal area was 8% in Case 1, 13% in Case 2, and 18% in Case 3.Conclusion: The increase in the average foveal thickness and the inner and outer foveal areas suggests that a centripetal movement of the inner and outer retinal layers toward the foveal center probably occurred due to the ILM peeling. Keywords: internal limiting membrane, optical coherence tomography, average foveal thickness, epiretinal membrane, vitrectomy

  5. Retinal thinning after internal limiting membrane peeling for idiopathic macular hole.

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    Imamura, Yutaka; Ishida, Masahiro

    2018-03-01

    To determine the changes in retinal thickness and whether they correlate with the size of the macular hole (MH) after vitrectomy with internal limiting membrane peeling. Retrospective, interventional case series METHODS: Consecutive patients with an MH and undergoing pars plana vitrectomy with internal limiting membrane peeling were studied. The retinal thicknesses in the inner 4 sectors as defined by the Early Treatment of Diabetic Retinopathy Study were measured using spectral-domain optical coherence tomography (SD-OCT) before and at 2 weeks and 1, 3, 6, and 12 months after the surgery. The basal and minimum diameters of the MHs were measured. The correlations between the retinal thicknesses and the size of the MH were determined. Thirty-three eyes of 32 consecutive patients (18 women; mean age, 64.2 ± 8.8 years) with an MH were studied. Thirteen eyes had a stage-2 MH; 12 eyes, a stage-3 MH; and 8 eyes, a stage-4 MH. The mean retinal thickness in the temporal sector was 362.8 ± 29.9 µm preoperatively, 337.9 ± 20.6 µm at 2 weeks postoperatively, and 307.6 ± 20.2 µm at 12 months postoperatively (P peeling.

  6. INTERNAL LIMITING MEMBRANE PEELING IN MACULAR HOLE SURGERY; WHY, WHEN, AND HOW?

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    Chatziralli, Irini P; Theodossiadis, Panagiotis G; Steel, David H W

    2018-05-01

    To review the current rationale for internal limiting membrane (ILM) peeling in macular hole (MH) surgery and to discuss the evidence base behind why, when, and how surgeons peel the ILM. Review of the current literature. Pars plana vitrectomy is an effective treatment for idiopathic MH, and peeling of the ILM has been shown to improve closure rates and to prevent postoperative reopening. However, some authors argue against ILM peeling because it results in a number of changes in retinal structure and function and may not be necessary in all cases. Furthermore, the extent of ILM peeling optimally performed and the most favorable techniques to remove the ILM are uncertain. Several technique variations including ILM flaps, ILM scraping, and foveal sparing ILM peeling have been described as alternatives to conventional peeling in specific clinical scenarios. Internal limiting membrane peeling improves MH closure rates but can have several consequences on retinal structure and function. Adjuvants to aid peeling, instrumentation, technique, and experience may all alter the outcome. Hole size and other variables are important in assessing the requirement for peeling and potentially its extent. A variety of evolving alternatives to conventional peeling may improve outcomes and need further study.

  7. Retinal Damage Induced by Internal Limiting Membrane Removal

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    Rachel Gelman

    2015-01-01

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

  8. Effect of internal limiting membrane peeling on the development of epiretinal membrane after pars plana vitrectomy for primary rhegmatogenous retinal detachment.

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    Nam, Ki Yup; Kim, Jung Yeul

    2015-05-01

    To investigate the difference in the occurrence of postoperative epiretinal membranes (ERMs) in vitrectomy for rhegmatogenous retinal detachment with and without peeling of the internal limiting membrane (ILM). The medical records of the 135 patients, who underwent vitrectomy for primary rhegmatogenous retinal detachment from November 2007 to August 2011, were analyzed retrospectively. Of the subjects, 70 patients underwent ILM peeling during the surgery and 65 did not. The best-corrected visual acuity, fundus photograph, and optical coherence tomography were collected 3, 6, and 12 months postoperatively. The relationship between ILM peeling and the preoperative findings of rhegmatogenous retinal detachment and development of a postoperative ERM was analyzed. No ERM occurred in the ILM peeling group, whereas an ERM occurred in 14 of 65 patients who underwent vitrectomy without ILM peeling (21.5%). This difference was significant (P peeling group and was significantly higher 12 months postoperatively (P = 0.03). Internal limiting membrane peeling seems to prevent the occurrence of a postoperative ERM in patients with primary rhegmatogenous retinal detachment.

  9. Multiple extrafoveal macular holes following internal limiting membrane peeling.

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    Hussain, Nazimul; Mitra, Sandip

    2018-01-01

    Internal limiting membrane (ILM) peeling has been the standard of treatment for macular holes. Besides, causing retinal nerve fiber layer surface abnormality, postoperative extrafoveal multiple retinal holes is a rare phenomenon following ILM peeling. We report an unusual complication of eight extrafoveal macular holes occurring following ILM peeling. A 60-year-old male presented with complaints of decreased and distorted vision in the right eye. He was diagnosed as having epiretinal membrane with lamellar macular hole. He underwent 23G pars plana vitrectomy, brilliant blue assisted ILM peeling and fluid gas exchange. Intraoperatively, ILM was found to be adherent to the underlying neurosensory retina. One month after cataract surgery, he underwent YAG capsulotomy in the right eye. He complained of visual distortion. His fundus evaluation in the right eye showed multiple (eight) extrafoveal retinal holes temporal to the macula clustered together. This case demonstrated that peeling of ILM, especially when it is adherent to the underlying neurosensory retina, may cause unwanted mechanical trauma to the inner retina. Glial apoptosis and neuronal degeneration may presumably play a role in delayed appearance of multiple (eight) extrafoveal macular holes, which has not been reported earlier.

  10. Vitrectomy with internal limiting membrane peeling versus inverted internal limiting membrane flap technique for macular hole-induced retinal detachment: a systematic review of literature and meta-analysis.

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    Yuan, Jing; Zhang, Ling-Lin; Lu, Yu-Jie; Han, Meng-Yao; Yu, Ai-Hua; Cai, Xiao-Jun

    2017-11-28

    To evaluate the effects on vitrectomy with internal limiting membrane (ILM) peeling versus vitrectomy with inverted internal limiting membrane flap technique for macular hole-induced retinal detachment (MHRD). Pubmed, Cochrane Library, and Embase were systematically searched for studies that compared ILM peeling with inverted ILM flap technique for macular hole-induced retinal detachment. The primary outcomes are the rate of retinal reattachment and the rate of macular hole closure 6 months later after initial surgery, the secondary outcome is the postoperative best-corrected visual acuity (BCVA) 6 months later after initial surgery. Four studies that included 98 eyes were selected. All the included studies were retrospective comparative studies. The preoperative best-corrected visual acuity was equal between ILM peeling and inverted ILM flap technique groups. It was indicated that the rate of retinal reattachment (odds ratio (OR) = 0.14, 95% confidence interval (CI):0.03 to 0.69; P = 0.02) and macular hole closure (OR = 0.06, 95% CI:0.02 to 0.19; P peeling. However, there was no statistically significant difference in postoperative best-corrected visual acuity (mean difference (MD) 0.18 logarithm of the minimum angle of resolution; 95% CI -0.06 to 0.43 ; P = 0.14) between the two surgery groups. Compared with ILM peeling, vitrectomy with inverted ILM flap technique resulted significantly higher of the rate of retinal reattachment and macular hole closure, but seemed does not improve postoperative best-corrected visual acuity.

  11. [Optical coherence tomography and microperimetry after internal limiting membrane peeling for epiretinal membrane].

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    Grimbert, P; Lebreton, O; Weber, M

    2014-06-01

    To evaluate the anatomical and functional consequences of internal limiting membrane (ILM) peeling in epiretinal membrane (ERM) surgery. Retrospective single-center study including consecutive patients operated on for idiopathic ERM. The integrity of the ILM was assessed by ILM Blue® staining after removal of the ERM: either the peeling was spontaneous (group 1) or a complementary peeling was required (group 2). Pre- and post-operatively (1 and 6 months), all patients were analyzed using visual acuity, SD-OCT (Spectralis HRA OCT, Heidelberg, Germany) and microperimetry (OPKO/OTI, Miami, USA). Twenty-one eyes of 21 patients were included: 12 "active ILM peelings" and 9 "spontaneous peelings". In both groups, visual acuity increased significantly after surgery. Microperimetry revealed more microscotomata at 1 and 6 months for active peeling (Ppeeling is frequently performed to reduce ERM recurrence. Despite lack of effect on visual acuity, active ILM peeling increases the incidence of microscotomas related to the site where the ERM or ILM is grasped. Active ILM peeling may be responsible for postoperative visual discomfort related to microscopic trauma during peeling. Copyright © 2014 Elsevier Masson SAS. All rights reserved.

  12. Photoreceptor change and visual outcome after idiopathic epiretinal membrane removal with or without additional internal limiting membrane peeling.

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    Ahn, Seong Joon; Ahn, Jeeyun; Woo, Se Joon; Park, Kyu Hyung

    2014-01-01

    To compare the postoperative photoreceptor status and visual outcome after epiretinal membrane removal with or without additional internal limiting membrane (ILM) peeling. Medical records of 40 eyes from 37 patients undergoing epiretinal membrane removal with residual ILM peeling (additional ILM peeling group) and 69 eyes from 65 patients undergoing epiretinal membrane removal without additional ILM peeling (no additional peeling group) were reviewed. The length of defects in cone outer segment tips, inner segment/outer segment junction, and external limiting membrane line were measured using spectral domain optical coherence tomography images of the fovea before and at 1, 3, 6, and 12 months after the surgery. Cone outer segment tips and inner segment/outer segment junction line defects were most severe at postoperative 1 month and gradually restored at 12 months postoperatively. The cone outer segment tips line defect in the additional ILM peeling group was significantly greater than that in the no additional peeling group at postoperative 1 month (P = 0.006), and best-corrected visual acuity was significantly worse in the former group at the same month (P = 0.001). There was no significant difference in the defect size and best-corrected visual acuity at subsequent visits and recurrence rates between the two groups. Patients who received epiretinal membrane surgery without additional ILM peeling showed better visual and anatomical outcome than those with additional ILM peeling at postoperative 1 month. However, surgical outcomes were comparable between the two groups, thereafter. In terms of visual outcome and photoreceptor integrity, additional ILM peeling may not be an essential procedure.

  13. [Drusen characteristics after internal limiting membrane peeling].

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    Lehmann, F; Jenisch, T; Helbig, H; Gamulescu, M A

    2015-05-01

    There are some reports showing isolated cases of drusen regression after pars plana vitrectomy (ppV) with peeling of the internal limiting membrane (iLM). Drusen characteristics after iLM peeling was investigated in this study. The data of 527 patients who had received iLM peeling between 2004 and 2012 were retrospectively collected and those patients with retinal drusen were selected for the study. Fundus photographs before and after vitrectomy due to a macular hole or epiretinal gliosis were compared and drusen arrangement in the peeling site was analyzed. The aim of the study was to show whether there was drusen regression 2-5 months after surgery. Out of the 527 patients 11 showed central macular drusen, 4 with confluent large drusen (> 63 µm diameter) and 7 with small hard drusen (≤ 63 µm diameter). One patient showed drusen regression after iLM peeling without any changes in the other eye and all other patients showed no differences in the drusen findings (n = 6) or even some additional drusen (n = 4) without drusen alterations in the other eye. The results of this study could not confirm some reports showing drusen regression after iLM peeling in the peeling site in general and there was only one single case of central drusen regression.

  14. Pars Plana Vitrectomy with Internal Limiting Membrane Peeling for Nontractional Diabetic Macular Edema.

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    Ulrich, Jan Niklas

    2017-01-01

    Diabetes mellitus remains the leading cause of blindness among working age Americans with diabetic macular edema being the most common cause for moderate and severe vision loss. To investigate the anatomical and visual benefits of pars plana vitrectomy with inner limiting membrane peeling in patients with nontractional diabetic macular edema as well as correlation of integrity of outer retinal layers on spectral domain optical coherence tomography to visual outcomes. We retrospectively reviewed the charts of 42 diabetic patients that underwent vitrectomy with internal limiting membrane peeling for nontractional diabetic macula edema. The integrity of outer retinal layers was evaluated and preoperative central macular thickness and visual acuity were compared with data at 1 month, 3 months and 6 months postoperatively. The student t-test was used to compare the groups. 31 eyes were included. While no differences were seen at 1 and 3 months, there was significant improvement of both central macular thickness and visual acuity at the 6 months follow up visit compared to preoperatively (357, 427 microns; p=0.03. 20/49, 20/82; p=0.03) . Patients with intact external limiting membrane and ellipsoid zone had better preoperative vision than patients with outer retinal layer irregularities (20/54, 20/100; p=0.03) and greater visual gains postoperatively (20/33, ppeeling can improve retinal anatomy and visual acuity in patients with nontractional diabetic macular edema. Spectral domain optical coherence tomography may help identify patients with potential for visual improvement.

  15. Internal Limiting Membrane Peeling to Prevent Post-vitrectomy Epiretinal Membrane Development in Retinal Detachment.

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    Akiyama, Kunihiko; Fujinami, Kaoru; Watanabe, Ken; Tsunoda, Kazushige; Noda, Toru

    2016-11-01

    To determine the efficacy of internal limiting membrane (ILM) peeling during vitrectomy for rhegmatogenous retinal detachment (RRD) regarding post-vitrectomy epiretinal membrane (ERM) development and visual outcomes. Retrospective, interventional, comparative case series. Setting: Institutional. One hundred and two consecutive eyes with RRD treated with vitrectomy and followed for at least 6 months. ILM was peeled without using dye such as indocyanine green (ICG). Observational Procedures: Patients were divided into 2 groups based on postoperative ERM development: Group 1, 81 eyes without ERM formation; Group 2, 21 eyes with ERM development. Patients also were divided into 2 subgroups: those with and without ILM peeling (58 and 44 eyes, respectively). Statistical analyses were performed between the 2 groups with/without ERM formation and between the 2 subgroups with/without ILM peeling for 5 preoperative factors including foveal involvement of the RRD, 4 intraoperative factors including ILM peeling, baseline best-corrected visual acuity (BCVA), and final BCVA. An association of ILM peeling with ERM prevention and the influence of ILM peeling on visual outcomes. ILM peeling was significantly (P peeling. ILM peeling without ICG staining during the initial vitrectomy for RRDs may prevent postoperative ERM formation with favorable visual outcomes. Copyright © 2016 Elsevier Inc. All rights reserved.

  16. Recurrence rate and need for reoperation after surgery with or without internal limiting membrane removal for the treatment of the epiretinal membrane.

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    De Novelli, Fernando José; Goldbaum, Mauro; Monteiro, Mario Luiz Ribeiro; Aggio, Fabio Bom; Nóbrega, Mario Junqueira; Takahashi, Walter Yukihiko

    2017-01-01

    To compare the recurrence rate and need for reoperation after epiretinal membrane surgery with and without removal of the internal limiting membrane. In this retrospective study, 125 patients operated for epiretinal membrane removal were evaluated, with a minimum 6-month follow-up. Removal of the epiretinal membrane (ERM) was performed in 78 patients, while 47 had removal of the epiretinal membrane associated with internal limiting membrane peeling (ERM + ILM). The mean age in the ERM group was 65.8 years old, ranging from 41 to 80 years old. In the ERM + ILM group, the mean age was 67.2 years old, ranging from 52 to 82 years old. The mean preoperative visual acuity in the ERM group was 20/80p, and in the ERM + ILM group, it was 20/80. The mean postoperative visual acuity in both groups was 20/30. The mean preoperative macular thickness in the ERM group was 467 µm ranging from 281 to 663 µm; in the ERM + ILM group, the preoperative macular thickness was 497 µm, ranging from 172 to 798 µm. After surgery, a reduction in macular thickness was observed in both groups. In the ERM group, the mean macular thickness reduction was 361 ± 101. µm, whereas in the ERM + ILM group, it was 367 ± 75.2 µm. Twenty-two patients presented with a recurrence of epiretinal membrane, of which 16 (20.5%) were from the ERM group and 6 (12.8%) were from the ERM + ILM group (p = 0.39); one patient (2%) was retreated in the ERM + ILM group, whereas 5 patients (6%) where retreated in the ERM group. We postulate that ILM peeling for the treatment of epiretinal membrane is not a relevant factor either for visual recovery or macular thickness reduction, but it may reduce the recurrence and reoperation rate.

  17. Eccentric Macular Hole after Pars Plana Vitrectomy for Epiretinal Membrane Without Internal Limiting Membrane Peeling: A Case Report.

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    Garnavou-Xirou, Christina; Xirou, Tina; Kabanarou, Stamatina; Gkizis, Ilias; Velissaris, Stavros; Chatziralli, Irini

    2017-12-01

    Postoperative eccentric macular hole formation is an uncommon complication after pars plana vitrectomy (PPV) without internal limiting membrane (ILM) peeling for the treatment of epiretinal membrane (ERM). We present a case of eccentric macular hole formation after PPV for ERM without ILM peeling. A 68-year-old male patient presented with ERM and visual acuity of 6/24 in his left eye. He underwent 23-gauge PPV without ILM peeling for treatment of ERM. One week postoperatively the retina was attached and the epiretinal membrane was successfully removed, while visual acuity was 6/9. One month after PPV, a single eccentric retinal hole below the macula was detected using fundoscopy and subsequently confirmed by optical coherence tomography. At this time the visual acuity was 6/9 and the patient reported no symptoms. No further intervention was attempted and at the 9-month follow-up, the visual acuity and the size of the eccentric macular hole remained stable. Eccentric macular holes can be developed after PPV even without ILM peeling and are usually managed conservatively by observation.

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

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    Uri Soiberman

    2016-01-01

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

  19. INTERNAL LIMITING MEMBRANE PEELING-DEPENDENT RETINAL STRUCTURAL CHANGES AFTER VITRECTOMY IN RHEGMATOGENOUS RETINAL DETACHMENT.

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    Hisatomi, Toshio; Tachibana, Takashi; Notomi, Shoji; Koyanagi, Yoshito; Murakami, Yusuke; Takeda, Atsunobu; Ikeda, Yasuhiro; Yoshida, Shigeo; Enaida, Hiroshi; Murata, Toshinori; Sakamoto, Taiji; Sonoda, Koh-Hei; Ishibashi, Tatsuro

    2018-03-01

    To examine retinal changes after vitrectomy with internal limiting membrane (ILM) peeling, we used 3-dimensional optical coherence tomography (3D-OCT) in rhegmatogenous retinal detachment cases. The 68 eyes from 67 patients with rhegmatogenous retinal detachment were studied, including 35 detached macula cases (51%) and 33 attached macula cases. Internal limiting membrane peeling was performed with fine forceps after brilliant blue G staining. The 3D-OCT images were obtained with volume-rendering technologies from cross-sectional OCT images. The 3D-OCT detected 45 eyes (66%) with ILM peeling-dependent retinal changes, including dissociated optic nerve fiber layer appearance, dimple sign, temporal macular thinning, ILM peeling area thinning, or forceps-related retinal thinning. The ILM peeled area was detectable in only 9 eyes with 3D-OCT, whereas it was undetectable in other 59 eyes. The dissociated optic nerve fiber layer appearance was detected in 8 of the total cases (12%), and dimple signs were observed in 14 cases (21%). Forceps-related thinning was also noted in eight cases (24%) of attached macula cases and in four cases (11%) of detached macula cases. No postoperative macular pucker was noted in the observational period. The 3D-OCT clearly revealed spatial and time-dependent retinal changes after ILM peeling. The changes occurred in 2 months and remained thereafter.

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

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    Hanhan Liu

    2015-01-01

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

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

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

    2015-01-01

    We conducted a meta-analysis of published retrospective studies and compared the effectiveness of pars plana vitrectomy with and without internal limiting membrane (ILM) peeling for idiopathic epiretinal membrane (IERM). The results revealed that patients in the IERM+ILM peeling group had better BCVA after surgery within 12 months than those in IERM peeling group. But patients in the IERM peeling group showed better BCVA in the 18th month. More retrospective studies or randomized controlled trials are required to investigate and compare the long-term effect of IERM removal with and without ILM peeling. PMID:26693348

  2. Changes in Retinal Thickness after Vitrectomy for Epiretinal Membrane with and without Internal Limiting Membrane Peeling.

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    Obata, Shumpei; Fujikawa, Masato; Iwasaki, Keisuke; Kakinoki, Masashi; Sawada, Osamu; Saishin, Yoshitsugu; Kawamura, Hajime; Ohji, Masahito

    2017-01-01

    To investigate anatomic changes in retinal thickness (RT) and functional changes after vitrectomy for idiopathic epiretinal membranes (ERMs) with and without internal limiting membrane (ILM) peeling. The medical records of 100 eyes of 96 patients with ERM who underwent vitrectomy and ERM removal were reviewed retrospectively. The RT was measured by optical coherence tomography, and the area was divided into 9 sections. The best-corrected visual acuity (BCVA), 9 RT areas, and incidence rates of recurrent ERM were compared between the groups with and without ILM peeling before the operation and 12 months postoperatively. Thirty-nine eyes that underwent vitrectomy with ILM peeling and 61 eyes that underwent vitrectomy without ILM peeling met the inclusion criteria. There were no significant differences between the groups in the BCVA and any of the RTs before the operation and 12 months postoperatively. The ERMs recurred in 8 (20.5%) of 39 eyes and 26 (42.6%) of 61 eyes in the groups with and without ILM peeling, respectively, with a difference that reached significance (p = 0.02) 12 months postoperatively. Vitrectomy for ERM affects the BCVA or the RTs 12 months postoperatively. Additional ILM peeling does not affect them, but it might reduce the ERM recurrence rate. © 2016 S. Karger AG, Basel.

  3. The role of internal limiting membrane peeling in epiretinal membrane surgery: a randomised controlled trial.

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    Tranos, Paris; Koukoula, Stavrenia; Charteris, Davic G; Perganda, Georgia; Vakalis, Athanasios; Asteriadis, Solon; Georgalas, Ilias; Petrou, Petros

    2017-06-01

    To compare the anatomical and functional outcomes after primary idiopathic epiretinal membrane (ERM) peeling with or without internal limiting membrane (ILM) peeling. A two-centre randomised, controlled clinical trial with 12 months of follow-up. One hundred and two eyes of 102 patients were included in the analysis and were randomised into two groups (ILM peeling (P) and non-ILM peeling (NP) group). Inclusion criteria were: Idiopathic ERM confirmed on optical coherence tomography, age ≥18 years, binocular distortion, best-corrected visual acuity (BCVA) ≤90 ETDRS letters, intraocular pressure ≤23 mm Hg and informed consent. The primary outcome measure was the mean change in the ETDRS distance BCVA at 12 months' follow-up for each group. The mean change in distance BCVA at 12 months was 0.30±0.24 logMAR (15 ETDRS letters) in the P group and 0.31±0.23 logMAR (14 ETDRS letters) in the NP group, a change that was not statistically significant (p=0.84). No statistically significant differences were observed when comparing the changes in distance BCVA, the changes in metamorphopsia (Amsler grid) and the changes in central retinal thickness between the two groups at any of the time points studied. Our analysis suggests that ILM peeling in idiopathic ERM surgery does not result in better visual improvement. The more frequent presence of an uninterrupted interdigitation zone in the P group did not result in a better functional outcome of our patients. No recurrent ERMs were noted in either group. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://www.bmj.com/company/products-services/rights-and-licensing/.

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

    Directory of Open Access Journals (Sweden)

    Shirakata Y

    2016-02-01

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

  5. COMPARATIVE ANALYSIS OF RETINAL REATTACHMENT SURGERY WITH OR WITHOUT INTERNAL LIMITING MEMBRANE PEELING TO PREVENT POSTOPERATIVE MACULAR PUCKER.

    Science.gov (United States)

    Forlini, Matteo; Date, Purva; Ferrari, Luisa Micelli; Lorusso, Massimo; Lecce, Gabriella; Verdina, Tommaso; Neri, Giovanni; Benatti, Caterina; Rossini, Paolo; Bratu, Adriana; DʼEliseo, Domenico; Ferrari, Tommaso Micelli; Cavallini, Gian Maria

    2017-07-18

    To determine whether internal limiting membrane (ILM) peeling during pars plana vitrectomy for rhegmatogenous retinal detachment reduces the incidence of epiretinal membrane (ERM) formation. In this retrospective study, preoperative, intraoperative, and postoperative data from all eyes undergoing pars plana vitrectomy for rhegmatogenous retinal detachment between January 2007 and December 2013 was analyzed. All cases with at least 1-year of follow-up were included. Data collection included vision, intraoperative complications, occurrence of ERM, and spectral domain optical coherence tomography characteristics. The OCTs were retrieved for all eyes and were graded by a single masked grader. Out of 159 eyes recruited, ILM peeling was done in 78 eyes (49%). Overall occurrence of ERM was 20%. Seven eyes (9%) in ILM peeling group and 25 eyes in the non-ILM peeling group (31%) showed ERM (P = 0.001). Postoperative vision was significantly better in eyes that had ILM peeling (0.48 ± 0.4 logarithm of the minimum angle of resolution [20/63] vs. 0.77 ± 0.6 logarithm of the minimum angle of resolution [20/125], P = 0.003). In multivariable models adjusting for type of tamponade, ILM peeling reduced the likelihood of ERM formation by 75% (P = 0.01). Internal limiting membrane peeling during pars plana vitrectomy for rhegmatogenous retinal detachment significantly reduces ERM formation in the postoperative period and is associated with better visual and anatomical outcomes.

  6. SURGICAL REMOVAL OF EPIRETINAL MEMBRANE WITH AND WITHOUT REMOVAL OF INTERNAL LIMITING MEMBRANE: Comparative Study of Visual Acuity, Features of Optical Coherence Tomography, and Recurrence Rate.

    Science.gov (United States)

    De Novelli, Fernando J; Goldbaum, Mauro; Monteiro, Mario L R; Bom Aggio, Fabio; Takahashi, Walter Y

    2017-12-05

    To study and compare visual acuity, foveal thickness, outer limiting layer, ellipsoid zone, and recurrence rate in patients undergoing removal of the epiretinal membrane with and without the removal of the internal limiting membrane (ILM). Sixty-three patients who had the epiretinal membrane removed by a single surgeon were randomly assigned into 2 groups: Group 1 without additional removal of the ILM and Group 2 with removal of the ILM. Patients were followed up and evaluated at the first month, third month, and sixth month, postoperatively. Patients from both groups had a gradual improvement in their vision over time. There was no significant difference in the improvement in visual acuity between the two groups. About tomographic assessment of alterations, no significant differences were found between the groups; however, Group 1 had a higher relapse rate (17%) compared with Group 2 (3.6%) (P = 0.09). Epiretinal membrane removal with and without ILM peeling shows similar functional and anatomical improvements, but the group in which the ILM was not removed seemed to have a higher recurrence rate.

  7. Five-Year Outcomes of Surgically Treated Symptomatic Epiretinal Membranes With and Without Internal Limiting Membrane Peeling.

    Science.gov (United States)

    Sultan, Harris; Wykoff, Charles C; Shah, Ankoor R

    2018-05-01

    The authors evaluated long-term postoperative visual outcomes and recurrence rates following surgery for symptomatic epiretinal membrane (ERM) ± internal limiting membrane (ILM) peeling. This was a retrospective, consecutive case series of 78 patients undergoing vitrectomy for symptomatic ERM between 1/2010 and 4/2012 with follow-up through at least postoperative year 5 (POY5). Outcomes included visual acuity (VA) (Snellen VA converted to logMAR), central retinal thickness (CRT; μm), and ERM recurrence. Subgroup analysis evaluated outcomes related to ILM peeling. Subgroup analysis based on ILM peeling did not find VA (20/50 [0.430 logMAR ± 0.061 logMAR; mean ± SD] vs. 20/60 [0.518 logMAR ± 0.128 logMAR] for ILM vs. non-ILM peeling respectively; P = .513) nor macular thickness (355 μm ± 13 μm vs. 360 μm ± 42 μm; P = .410) to be significantly different at POY5. Recurrence requiring surgery with and without ILM peeling was not statistically significantly different at POY5 (1.6% and 11.8%; P = .118). Vitrectomy for symptomatic ERM led to improved visual and anatomic outcomes with sustained benefit through 5 years. ILM peeling was was associated with reduced ERM recurrence, but this benefit was not statistically significant at POY5. [Ophthalmic Surg Lasers Imaging Retina. 2018;49:296-302.]. Copyright 2018, SLACK Incorporated.

  8. Postoperative eccentric macular holes after vitrectomy and internal limiting membrane peeling.

    Science.gov (United States)

    Brouzas, Dimitrios; Dettoraki, Maria; Lavaris, Anastasios; Kourvetaris, Dimitrios; Nomikarios, Nikolaos; Moschos, Marilita M

    2017-06-01

    The purpose of this study was to describe the incidence, clinical characteristics, and outcome of eccentric macular holes presenting after vitrectomy and internal limiting membrane (ILM) peeling for the treatment of macular pathology and discuss the pathogenesis of holes formation. A retrospective, noncomparative, interventional case-series study of five patients who developed eccentric macular holes postoperatively following vitrectomy in 198 consecutive patients who underwent ILM peeling for idiopathic macular hole and epiretinal membrane formation between 2008 and 2015. Five patients (2.5 %) developed full-thickness eccentric macular holes postoperatively. Three patients presented with a single eccentric macular hole, one patient had an eccentric hole after a failed idiopathic macular hole surgery and one patient developed four eccentric macular holes. The mean diameter of the holes was 584 μm (range 206-1317 μm) and the average time of holes formation after vitrectomy was 27.7 weeks (range 1-140 weeks). Postoperative best-corrected visual acuity ranged from "counting fingers" to 20/25. The eyes with the holes distant from the fovea had the best final visual acuity. No further intervention was attempted and no complications occurred. The mean follow-up time was 26.8 months. The postoperative macular holes after vitrectomy and ILM peeling were variable in number, size, and time of appearance but remained stable and were not associated with any complications. The pathogenesis of macular holes is most consistent with contraction of the residual ILM or secondary epimacular proliferation probably stimulated by ILM peeling.

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

    Science.gov (United States)

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

    2017-09-08

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

  10. Limited and selective transfer of plasma membrane glycoproteins to membrane of secondary lysosomes

    International Nuclear Information System (INIS)

    Haylett, T.; Thilo, L.

    1986-01-01

    Radioactive galactose, covalently bound to cell surface glycoconjugates on mouse macrophage cells, P388D 1 , was used as a membrane marker to study the composition, and the kinetics of exchange, of plasma membrane-derived constituents in the membrane of secondary lysosomes. Secondary lysosomes were separated from endosomes and plasma membrane by self-forming Percoll density gradients. Horseradish peroxidase, taken up by fluid-phase pinocytosis, served as a vesicle contents marker to monitor transfer of endosomal contents into secondary lysosomes. Concurrently, the fraction of plasma membrane-derived label of secondary lysosomes increased by first order kinetics from 4 PAGE, labeled molecules of M/sub r/ 160-190 kD were depleted and of the M/sub r/ 100-120 kD were enriched in lysosome membrane compared with the relative composition of label on the cell surface. No corresponding selectivity was observed for the degradation of label, with all M/sub r/ classes being affected to the same relative extent. The results indicate that endocytosis-derived transfer of plasma membrane constitutents to secondary lysosomes is a limited and selective process, and that only ∼1% of internalized membrane is recycled via a membrane pool of secondary lysosomes

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

    DEFF Research Database (Denmark)

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

    2013-01-01

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

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

    Directory of Open Access Journals (Sweden)

    Das Taraprasad

    2003-01-01

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

  13. Decreased retinal sensitivity after internal limiting membrane peeling for macular hole surgery.

    Science.gov (United States)

    Tadayoni, Ramin; Svorenova, Ivana; Erginay, Ali; Gaudric, Alain; Massin, Pascale

    2012-12-01

    To compare the retinal sensitivity and frequency of microscotomas found by spectral domain optical coherence tomography (SD-OCT) combined with scanning laser ophthalmoscopy (SLO) microperimetry after idiopathic macular hole closure, in eyes that underwent internal limiting membrane (ILM) peeling and eyes that did not. This was a retrospective, non-randomised, comparative study. Combined SD-OCT and SLO microperimetry was performed in 16 consecutive eyes after closure of an idiopathic macular hole. A customised microperimetry pattern with 29 measurement points was used. The ILM was peeled in 8/16 eyes. The main outcome measure was mean retinal sensitivity. Mean retinal sensitivity (in dB) was lower after peeling: 9.80 ± 2.35 dB with peeling versus 13.19 ± 2.92 without (p=0.0209). Postoperative microscotomas were significantly more frequent after ILM peeling: 11.3 ± 6.6 points with retinal sensitivity below 10 dB in eyes that underwent peeling versus 2.9 ± 4.6 in those that did not (p=0.0093). These results suggest that ILM peeling may reduce retinal sensitivity, and significantly increase the incidence of microscotomas. Until a prospective trial confirming or not these results, it seems justified to avoid peeling the ILM when its potential benefit seems minor or unproved, and when peeling is carried out, to limit the surface peeled to the bare minimum.

  14. Two Cases of Severe Degeneration of the Macula Following Vitrectomy with Indocyanine Green-Assisted Internal Limiting Membrane Peeling for Idiopathic Macular Hole

    OpenAIRE

    Inoue, Junji; Sakuma, Toshiro; Kiyokawa, Masatoshi; Kobayashi, Yasuhiko; Takebayashi, Hiroshi; Mizota, Atsushi; Tanaka, Minoru

    2008-01-01

    We describe three eyes of two cases of severe degeneration of the macula following vitrectomy with indocyanine green-assisted internal limiting membrane peeling for idiopathic macular hole. We need to remember the possibility of these complications and have to select the procedures that are safest to use for macular hole surgery.

  15. Clinical and cost-effectiveness of internal limiting membrane peeling for patients with idiopathic full thickness macular hole. Protocol for a Randomised Controlled Trial: FILMS (Full-thickness macular hole and Internal Limiting Membrane peeling Study

    Directory of Open Access Journals (Sweden)

    Cook Jonathan

    2008-11-01

    Full Text Available Abstract Background A full-thickness macular hole (FTMH is a common retinal condition associated with impaired vision. Randomised controlled trials (RCTs have demonstrated that surgery, by means of pars plana vitrectomy and post-operative intraocular tamponade with gas, is effective for stage 2, 3 and 4 FTMH. Internal limiting membrane (ILM peeling has been introduced as an additional surgical manoeuvre to increase the success of the surgery; i.e. increase rates of hole closure and visual improvement. However, little robust evidence exists supporting the superiority of ILM peeling compared with no-peeling techniques. The purpose of FILMS (Full-thickness macular hole and Internal Limiting Membrane peeling Study is to determine whether ILM peeling improves the visual function, the anatomical closure of FTMH, and the quality of life of patients affected by this disorder, and the cost-effectiveness of the surgery. Methods/Design Patients with stage 2–3 idiopathic FTMH of less or equal than 18 months duration (based on symptoms reported by the participant and with a visual acuity ≤ 20/40 in the study eye will be enrolled in this FILMS from eight sites across the UK and Ireland. Participants will be randomised to receive combined cataract surgery (phacoemulsification and intraocular lens implantation and pars plana vitrectomy with postoperative intraocular tamponade with gas, with or without ILM peeling. The primary outcome is distance visual acuity at 6 months. Secondary outcomes include distance visual acuity at 3 and 24 months, near visual acuity at 3, 6, and 24 months, contrast sensitivity at 6 months, reading speed at 6 months, anatomical closure of the macular hole at each time point (1, 3, 6, and 24 months, health related quality of life (HRQOL at six months, costs to the health service and the participant, incremental costs per quality adjusted life year (QALY and adverse events. Discussion FILMS will provide high quality evidence on the

  16. [Internal limiting membrane peeling as prophylaxis of epimacular membrane formation in eyes undergoing vitrectomy for rhegmatogenous retinal detachement].

    Science.gov (United States)

    Hejsek, L; Dusová, J; Stepanov, A; Rozsíval, P

    2014-06-01

    Rhegmatogenous retinal detachment is a serious condition that can significantly impair visual function, even after a successful surgery. One of the complications that can significantly impair visual acuity in the postoperative period is a development of the epimacular membrane (ERM). The aim of this work is to monitor the effect of peeling of the internal limiting membrane (ILM) in the macula at the anatomical and functional results in the postoperative period, especially with regard to the development of ERM. Prospective study of 21 eyes, which underwent peeling of ILM during pars plana vitrectomy for rhegmatogenous retinal detachment (on detached macula). The ILM peeling was done without using decalin during this procedure. We tested best corrected visual acuity (BCVA) and followed fundus biomicroscopic findings. Proliferative vitreoretinopathy (PVR) was evaluated according to the recommendations of the Retina Society Terminology Committee. To exclude the development of ERM in the macula optical coherence tomography (OCT) was performed at the end of the 18-month follow-up period. In total, the results of 21 eyes of 21 patients who underwent PPV for rhegmatogenous retinal detachment were evaluated. In all of them was during PPV performed ILM peeling on detached macula, these are followed prospectively. ILM peeling without using decalin was sufficient in all eyes. All eyes with ILM peeling did not develop ERM at the end of the follow-up period. ILM peeling during PPV for rhegmatogenous retinal detachment reduces the risk of developing secondary ERM.

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

    DEFF Research Database (Denmark)

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

    2014-01-01

    OBJECTIVE: To determine whether internal limiting membrane (ILM) peeling improves anatomic and functional outcomes of full-thickness macular hole (FTMH) surgery when compared with the no-peeling technique. DESIGN: Systematic review and individual participant data (IPD) meta-analysis undertaken...... under the auspices of the Cochrane Eyes and Vision Group. Only randomized controlled trials (RCTs) were included. PARTICIPANTS AND CONTROLS: Patients with idiopathic stage 2, 3, and 4 FTMH undergoing vitrectomy with or without ILM peeling. INTERVENTION: Macular hole surgery, including vitrectomy and gas...... endotamponade with or without ILM peeling. MAIN OUTCOME MEASURES: Primary outcome was best-corrected distance visual acuity (BCdVA) at 6 months postoperatively. Secondary outcomes were BCdVA at 3 and 12 months; best-corrected near visual acuity (BCnVA) at 3, 6, and 12 months; primary (after a single surgery...

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

    DEFF Research Database (Denmark)

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

    2010-01-01

    Aim: To examine postoperative macular morphology and visual outcome after 12 months in relation to internal limiting membrane (ILM) peeling versus no peeling, indocyanine green (ICG) staining and re-operation in eyes that achieved macular hole closure after surgery. Methods: Seventy-four eyes...... with closed stage 2 or 3 macular holes were recruited from a randomised clinical trial comparing: (1) vitrectomy without ILM peeling; (2) vitrectomy with 0.05% isotonic ICG-assisted ILM peeling; and (3) vitrectomy with 0.15% trypan blue-assisted ILM peeling. Contrast-enhanced Stratus optical coherence...... between subgroups. Conclusions: Poor vision after 12 months despite macular hole closure was associated with attenuation and disruption of the foveolar photoreceptor matrix. The extent of attenuation and disruption was independent of peeling and staining....

  19. Displacement of fovea toward optic disk after macular hole surgery with internal limiting membrane peeling.

    Science.gov (United States)

    Ohta, Kouichi; Sato, Atsuko; Senda, Nami; Fukui, Emi

    2017-01-01

    The purpose of this study was to demonstrate a displacement of the foveal depression toward the optic disk after idiopathic macular hole (MH) surgery with internal limiting membrane (ILM) peeling. Two patients with a unilateral MH developed an MH in the fellow eyes. Vitrectomy with ILM peeling was performed on the fellow eye to close the MH. Images of spectral-domain optical coherence tomography (SD-OCT) were used to measure the disk-to-fovea distances pre MH formation, after MH formation, and 6 months after the closure of the MH. The disk-to-fovea distance was shorter at 6 months than after the development of the MH (4,109 µm and 4,174 µm in Case 1 and 4,001 µm and 4,051 µm in Case 2). These results indicate that the fovea moves nasally after the MH surgery with ILM peeling.

  20. Inner retinal thinning after Brilliant Blue G-assisted internal limiting membrane peeling for vitreoretinal interface disorders.

    Science.gov (United States)

    Ambiya, Vikas; Goud, Abhilash; Khodani, Mitali; Chhablani, Jay

    2017-04-01

    The aim of this study was to evaluate ganglion cell layer and nerve fiber layer thickness after Brilliant Blue G (BBG)-assisted internal limiting membrane (ILM) peeling for vitreomacular disorders. Retrospective analysis of spectral domain optical coherence tomography (SD-OCT) of 42 eyes of 42 patients, who underwent pars plana vitrectomy with BBG-assisted ILM peeling, was performed. Inclusion criteria were idiopathic macular hole, idiopathic vitreomacular traction, and idiopathic epiretinal membrane. Key exclusion criteria were vitreoretinal interface abnormalities secondary to any other diseases, follow-up period of less than 3 months, and any other associated retinal pathology. Average, minimum, and sectoral ganglion cell, and inner plexiform layers (GCIPL) and retinal nerve fiber layer (RNFL) parameters were collected. Changes in these parameters from baseline to 3- and 6-month visits after surgery were analyzed. At 3 months after surgery, we found a statistically significant reduction in the average GCIPL thickness (P = 0.031) and also in the superior sectors (P peeling for vitreomacular interface disorders leads to thinning of the inner retina including GCIPL and RNFL. These structural changes should be correlated with retinal function tests to explore the pros and cons of this surgical step.

  1. Vitrectomy with or without internal limiting membrane peeling for idiopathic epiretinal membrane: A meta-analysis.

    Science.gov (United States)

    Chang, Wei-Cheng; Lin, Chin; Lee, Cho-Hao; Sung, Tzu-Ling; Tung, Tao-Hsin; Liu, Jorn-Hon

    2017-01-01

    Studies on vitrectomy with and without internal limiting membrane (ILM) peeling for idiopathic epiretinal membrane (ERM) have yielded uncertain results regarding clinical outcomes and recurrence rates. To compare the clinical outcomes of vitrectomy with and without ILM peeling for idiopathic ERM. Databases, including PubMed, Embase, Cochrane, Web of Science, Google Scholar, CNKI databases, FDA.gov, and ClinicalTrials.gov, published until July 2016, were searched to identify studies comparing the clinical outcomes following vitrectomy with ERM and ILM peeling and with only ERM peeling, for treating idiopathic ERM. Studies with sufficient data were selected. Pooled results were expressed as mean differences (MDs) and risk ratios (RRs) with corresponding 95% confidence intervals (CI) for vitrectomy with and without ILM peeling with regard to postoperative best corrected visual acuity (BCVA), central retinal thickness (CRT), and ERM recurrence rate. Eleven retrospective studies and one randomized controlled trial involving 756 eyes were identified. This demonstrated that the postoperative BCVA within 12 months was significantly better in the non-ILM peeling group (MD = 0.04, 95% CI: 0.00 to 0.08; P = 0.0460), but that the patients in the ILM peeling group had significantly better postoperative BCVA after 18 months (MD = -0.13, 95% CI: -0.23 to -0.04; P = 0.0049) than did those in the non-ILM peeling group. The non-ILM peeling group exhibited a higher reduction in postoperative CRT (MD = 51.55, 95% CI:-84.23 to -18.88; P = 0.0020) and a higher recurrence rate of ERM (RR = 0.34, 95% CI:0.16 to 0.72; P = 0.0048) than did the ILM peeling group. However, the improvement rates of BCVA (RR = 1.03, 95% CI:0.72 to 1.47; P = 0.8802) and postoperative CRTs (MD = 18.15, 95% CI:-2.29 to 38.60; P = 0.0818) were similar between the two groups. Vitrectomy with ILM peeling results in better visual improvement in long-term follow-ups and lower ERM recurrence rates, and vitrectomy with

  2. Retinal thickness after vitrectomy and internal limiting membrane peeling for macular hole and epiretinal membrane

    Science.gov (United States)

    Kumagai, Kazuyuki; Ogino, Nobuchika; Furukawa, Mariko; Hangai, Masanori; Kazama, Shigeyasu; Nishigaki, Shirou; Larson, Eric

    2012-01-01

    Purpose To determine the retinal thickness (RT), after vitrectomy with internal limiting membrane (ILM) peeling, for an idiopathic macular hole (MH) or an epiretinal membrane (ERM). Also, to investigate the effect of a dissociated optic nerve fiber layer (DONFL) appearance on RT. Methods A non-randomized, retrospective chart review was performed for 159 patients who had successful closure of a MH, with (n = 148), or without (n = 11), ILM peeling. Also studied were 117 patients who had successful removal of an ERM, with (n = 104), or without (n = 13), ILM peeling. The RT of the nine Early Treatment Diabetic Retinopathy Study areas was measured by spectral domain optical coherence tomography (SD-OCT). In the MH-with-ILM peeling and ERM-with-ILM peeling groups, the RT of the operated eyes was compared to the corresponding areas of normal fellow eyes. The inner temporal/inner nasal ratio (TNR) was used to assess the effect of ILM peeling on RT. The effects of DONFL appearance on RT were evaluated in only the MH-with-ILM peeling group. Results In the MH-with-ILM peeling group, the central, inner nasal, and outer nasal areas of the retina of operated eyes were significantly thicker than the corresponding areas of normal fellow eyes. In addition, the inner temporal, outer temporal, and inner superior retina was significantly thinner than in the corresponding areas of normal fellow eyes. Similar findings were observed regardless of the presence of a DONFL appearance. In the ERM-with-ILM peeling group, the retina of operated eyes was significantly thicker in all areas, except the inner and outer temporal areas. In the MH-with-ILM peeling group, the TNR was 0.86 in operated eyes, and 0.96 in fellow eyes (P peeling group, the TNR was 0.84 in operated eyes, and 0.95 in fellow eyes (P peeling group was 0.98, which was significantly greater than that of the MH-with-ILM peeling group (P peeling group was 0.98, which was significantly greater than that of ERM-with-ILM peeling

  3. INCOMPLETE REPAIR OF RETINAL STRUCTURE AFTER VITRECTOMY WITH INTERNAL LIMITING MEMBRANE PEELING.

    Science.gov (United States)

    Hisatomi, Toshio; Tachibana, Takashi; Notomi, Shoji; Nakatake, Shunji; Fujiwara, Kohta; Murakami, Yusuke; Ikeda, Yasuhiro; Yoshida, Shigeo; Enaida, Hiroshi; Murata, Toshinori; Sakamoto, Taiji; Sonoda, Koh-Hei; Ishibashi, Tatsuro

    2017-08-01

    To examine retinal changes after vitrectomy with internal limiting membrane (ILM) peeling, we used a cynomolgus monkey model and focused on surgical damages of ILM peeling for long observational period of 3 years. Vitrectomy was performed followed by ILM peeling similar to clinical settings in humans. Ultrastructural changes of the retina were investigated by light, transmission, and scanning electron microscopy at 3 months and 3 years after ILM peeling. Ultrastructural study showed that the ILM peeled area was still clearly recognized after 3 years. The Müller cell processes covered most of the retina; however, the nerve fiber layer was partly uncovered and exposed to the vitreous space. The arcuate linear nerve fiber bundles were observed as comparable with dissociated optic nerve fiber layer appearance. Small round retinal surface defects were also observed around macula, resembling the dimple sign. Forceps-related retinal thinning was also found on the edge of ILM peeling, where we started peeling with fine forceps. The ultrastructural studies showed that most of ILM peeling area was covered with glial cells during wound healing processes. Retinal changes were found comparable with dissociated optic nerve fiber layer appearance or dimple sign, which were clinically observed with optical coherence tomography.

  4. Autologous transplantation of the internal limiting membrane for refractory macular holes.

    Science.gov (United States)

    Morizane, Yuki; Shiraga, Fumio; Kimura, Shuhei; Hosokawa, Mio; Shiode, Yusuke; Kawata, Tetsuhiro; Hosogi, Mika; Shirakata, Yukari; Okanouchi, Toshio

    2014-04-01

    To determine the effectiveness of autologous transplantation of the internal limiting membrane (ILM) for refractory macular holes. Prospective, interventional case series. Ten eyes of 10 consecutive patients who underwent autologous transplantation of the ILM for the treatment of refractory macular holes were studied. The primary diseases in these patients were large idiopathic macular holes that had existed for more than 1 year (4 eyes), a traumatic macular hole (1 eye), myopic foveoschisis (2 eyes), foveoschisis resulting from pit-macular syndrome (2 eyes), and proliferative diabetic retinopathy (1 eye). Apart from the 5 eyes with idiopathic or traumatic macular holes, macular holes developed in the other 5 eyes after initial vitrectomies with ILM removal. In all eyes, regular macular hole surgery failed to achieve closure. The main outcome measures used in this study were macular hole closure and best-corrected visual acuity (BCVA). Macular holes were closed successfully in 9 eyes (90%) after autologous transplantation of the ILM. The postoperative BCVAs were significantly better than the preoperative BCVAs (P = .007, paired t test). Postoperative BCVAs improved by more than 0.2 logarithm of the minimal angle of resolution units in 8 eyes (80%) and were unchanged in 2 eyes (20%). Although this is a pilot study, the results suggest that autologous transplantation of the ILM may contribute to improved anatomic and visual outcomes in the treatment of refractory macular holes and may warrant further investigation. Copyright © 2014 Elsevier Inc. All rights reserved.

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

    Directory of Open Access Journals (Sweden)

    Kase S

    2016-12-01

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

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

    Directory of Open Access Journals (Sweden)

    Jie Dong

    2013-06-01

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

  7. Internal limiting membrane peeling in macula-off retinal detachment complicated by grade B proliferative vitreoretinopathy.

    Science.gov (United States)

    Foveau, Pauline; Leroy, Bertrand; Berrod, Jean-Paul; Conart, Jean-Baptiste

    2018-04-02

    To investigate the clinical benefit of internal limiting membrane (ILM) peeling as a surgical adjunct in the repair of primary retinal detachment (RD) complicated by grade B proliferative vitreoretinopathy (PVR). Retrospective, interventional, comparative case series. SETTING: Institutional. 75 consecutive patients who underwent vitrectomy for primary macula off RD complicated by grade B PVR. Patients were divided into an ILM peeling (group P) and a no ILM peeling (group NP). Anatomical success rate, best-corrected visual acuity, and spectral-domain optical coherence tomography (SD-OCT) characteristics were collected at 1 and 6 months. In all, 37 eyes with ILM peeling were included in group P and 38 eyes without ILM peeling were included in group NP. The anatomical success rate after single surgery was higher in group P (89%) than in group NP (66%, p=0.03). Mean final visual acuity was 0.41 ±0.40 logMAR in group P versus 0.43 ±0.22 logMAR in group NP (p=0.82). We found no epiretinal membrane (ERM) formation in group P, whereas five cases of ERM (20%) were detected in group NP (p=0.012). The two groups did not differ in terms of cystoid macular edema occurrence, macular thickness, or photoreceptor damage. ILM peeling during vitrectomy in macula off RD complicated by grade B PVR reduces the need for a second surgery for re-detachment or macular pucker. Copyright © 2018. Published by Elsevier Inc.

  8. Internal limiting membrane peeling or not: a systematic review and meta-analysis of idiopathic macular pucker surgery.

    Science.gov (United States)

    Fang, Xiao-Ling; Tong, Yao; Zhou, Ya-Li; Zhao, Pei-Quan; Wang, Zhao-Yang

    2017-11-01

    To determine whether internal limiting membrane (ILM) peeling improves anatomical and functional outcomes in idiopathic macular pucker (IMP)/epiretinal membrane (ERM) surgery in this systematic review and meta-analysis. We searched the PubMed, Medline, Web of Science, Cochrane, Ovid MEDLINE, ClinicalTrials.gov and CNKI databases for studies published before 15 September 2016. The eligibility criteria included studies comparing ILM peeling versus no-peeling for IMP surgery. Thirteen articles (10 retrospective cohort studies, 1 prospective cohort study and 2 randomised controlled trials (RCTs)) were included in the review. Primary outcomes: no differences were observed in the best-corrected visual acuity (BCVA) or central macular thickness (CMT) at 12 months; however, lower ERM recurrence (OR, 0.13; 95% CI 0.04 to 0.41; p=0.0004) and reoperation rates (OR, 0.10; 95% CI 0.02 to 0.49; p=0.004) that favoured ILM peeling were observed at the final follow-up. no difference was observed in BCVA at 3, 6 months, the final follow-up or in CMT at 3, 6 months, the final follow-up. Significantly increased CMT, which favoured ILM peeling, was observed at the final follow-up (p=0.002) in the RCTs. ILM peeling yielded greater anatomical success, but no improvement in functional outcomes as the treatment of choice for patients undergoing IMP surgery. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://www.bmj.com/company/products-services/rights-and-licensing/.

  9. EFFECTS OF INTERNAL LIMITING MEMBRANE PEELING COMBINED WITH REMOVAL OF IDIOPATHIC EPIRETINAL MEMBRANE: A Systematic Review of Literature and Meta-Analysis.

    Science.gov (United States)

    Azuma, Kunihiro; Ueta, Takashi; Eguchi, Shuichiro; Aihara, Makoto

    2017-10-01

    To evaluate the effects on postoperative prognosis of internal limiting membrane (ILM) peeling in conjunction with removal of idiopathic epiretinal membranes (ERMs). MEDLINE, Cochrane Central Register of Controlled Trials (CENTRAL), and EMBASE were systematically searched for studies that compared ILM peeling with no ILM peeling in surgery to remove idiopathic ERM. Outcome measures were best-corrected visual acuity, central macular thickness, and ERM recurrence. Studies that compared ILM peeling with no ILM peeling for the treatment of idiopathic ERM were selected. Sixteen studies that included 1,286 eyes were selected. All the included studies were retrospective or prospective comparative studies; no randomized controlled study was identified. Baseline preoperative best-corrected visual acuity and central macular thickness were equal between ILM peeling and no ILM peeling groups. Postoperatively, there was no statistically significant difference in best-corrected visual acuity (mean difference 0.01 logarithm of the minimum angle of resolution [equivalent to 0.5 Early Treatment Diabetic Retinopathy Study letter]; 95% CI -0.05 to 0.07 [-3.5 to 2.5 Early Treatment Diabetic Retinopathy Study letters]; P = 0.83) or central macular thickness (mean difference 13.13 μm; 95% CI -10.66 to 36.93; P = 0.28). However, the recurrence rate of ERM was significantly lower with ILM peeling than with no ILM peeling (odds ratio 0.25; 95% CI 0.12-0.49; P peeling in vitrectomy for idiopathic ERM could result in a significantly lower ERM recurrence rate, but it does not significantly influence postoperative best-corrected visual acuity and central macular thickness.

  10. Microvascular changes after vitrectomy with internal limiting membrane peeling: an optical coherence tomography angiography study.

    Science.gov (United States)

    Mastropasqua, Leonardo; Borrelli, Enrico; Carpineto, Paolo; Toto, Lisa; Di Antonio, Luca; Mattei, Peter A; Mastropasqua, Rodolfo

    2017-06-19

    To evaluate superficial capillary plexus (SCP) changes occurring after internal limiting membrane (ILM) peeling for the treatment of idiopathic epiretinal membrane (ERM). A total of 15 eyes of 15 patients affected by idiopathic ERM (eight males and seven females; mean age 59.8 ± 9.6 years) were enrolled in the study. Patients were treated with pars plana vitrectomy followed by ERM and ILM peeling. Subjects were evaluated at baseline and at the week-1 and month-1 follow-up visits. At each visit, patients were evaluated with a complete ophthalmologic evaluation, which included imaging with optical coherence tomography angiography. Overall, the SCP vessel density was 43.0 ± 3.0% at baseline and was stable throughout the follow-up (40.0 ± 4.0% at week-1 and 41.0 ± 4.0% at month-1 follow-up visits; p = 0.087 and p = 0.426, respectively). Nevertheless, the SCP vessel density was reduced at week-1 visit in both the superior and inferior sectors. In these sectors, the superficial vessel density was still reduced at the month-1 follow-up visit. We observed a reduction in the SCP vessel density occurring after pars plana vitrectomy with ILM peeling. The reduction is referred to those areas where other changes (e.g., swelling of the arcuate nerve fiber layer) have been already described. In theory, superficial vessel density modifications may be due to the direct surgical trauma to the inner retina, where the superficial plexus is contained, during the ILM grasping.

  11. Tomographic Structural Changes of Retinal Layers after Internal Limiting Membrane Peeling for Macular Hole Surgery.

    Science.gov (United States)

    Faria, Mun Yueh; Ferreira, Nuno P; Cristóvao, Diana M; Mano, Sofia; Sousa, David Cordeiro; Monteiro-Grillo, Manuel

    2018-01-01

    To highlight tomographic structural changes of retinal layers after internal limiting membrane (ILM) peeling in macular hole surgery. Nonrandomized prospective, interventional study in 38 eyes (34 patients) subjected to pars plana vitrectomy and ILM peeling for idiopathic macular hole. Retinal layers were assessed in nasal and temporal regions before and 6 months after surgery using spectral domain optical coherence tomography. Total retinal thickness increased in the nasal region and decreased in the temporal region. The retinal nerve fiber layer (RNFL), ganglion cell layer (GCL), and inner plexiform layer (IPL) showed thinning on both nasal and temporal sides of the fovea. The thickness of the outer plexiform layer (OPL) increased. The outer nuclear layer (ONL) and outer retinal layers (ORL) increased in thickness after surgery in both nasal and temporal regions. ILM peeling is associated with important alterations in the inner retinal layer architecture, with thinning of the RNFL-GCL-IPL complex and thickening of OPL, ONL, and ORL. These structural alterations can help explain functional outcome and could give indications regarding the extent of ILM peeling, even though peeling seems important for higher rate of hole closure. © 2017 S. Karger AG, Basel.

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

    DEFF Research Database (Denmark)

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

    2012-01-01

    The functionality of membrane proteins is often modulated by the surrounding membrane. Here, we investigated the effect of membrane reconstitution of purified cytochrome c oxidase (CytcO) on the kinetics and thermodynamics of internal electron and proton-transfer reactions during O-2 reduction...... DOPC lipids. In conclusion, the data show that the membrane significantly modulates internal charge-transfer reactions and thereby the function of the membrane-bound enzyme.......-glycerol) (DOPG). In addition, a small Change in the internal Cu-A-heme a electron equilibrium constant was observed. This effect was lipid-dependent and explained in terms of a lower electrostatic potential within the membrane-spanning part of the protein with the anionic DOPG lipids than with the zwitterionic...

  13. Relationship between Peeled Internal Limiting Membrane Area and Anatomic Outcomes following Macular Hole Surgery: A Quantitative Analysis

    Directory of Open Access Journals (Sweden)

    Yasin Sakir Goker

    2016-01-01

    Full Text Available Purpose. To quantitatively evaluate the effects of peeled internal limiting membrane (ILM area and anatomic outcomes following macular hole surgery using spectral domain optical coherence tomography (SD-OCT. Methods. Forty-one eyes in 37 consecutive patients with idiopathic, Gass stage 3-4 macular hole (MH were enrolled in this retrospective comparative study. All patients were divided into 2 groups according to anatomic success or failure. Basal MH diameter, peeled ILM area, and MH height were calculated using SD-OCT. Other prognostic parameters, including age, stage, preoperative BCVA, and symptom duration were also assessed. Results. Thirty-two cases were classified as anatomic success, and 9 cases were classified as anatomic failure. Peeled ILM area was significantly wider and MH basal diameter was significantly less in the anatomic success group (p=0.024 and 0.032, resp.. Other parameters did not demonstrate statistical significance. Conclusion. The findings of the present study show that the peeled ILM area can affect the anatomic outcomes of MH surgery.

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

    Directory of Open Access Journals (Sweden)

    Nohutcu A

    2011-08-01

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

  15. SWEPT-SOURCE OPTICAL COHERENCE TOMOGRAPHY ANGIOGRAPHY REVEALS INTERNAL LIMITING MEMBRANE PEELING ALTERS DEEP RETINAL VASCULATURE.

    Science.gov (United States)

    Michalewska, Zofia; Nawrocki, Jerzy

    2018-04-30

    To describe morphology of retinal and choroidal vessels in swept-source optical coherence tomography angiography before and after vitrectomy with the temporal inverted internal limiting membrane (ILM) flap technique for full-thickness macular holes. Prospective, observational study of 36 eyes of 33 patients with full-thickness macular holes swept-source optical coherence tomography angiography was performed in patients before and 1 month after vitrectomy. Vitrectomy with the temporal inverted ILM flap technique was performed. In this method, ILM is peeled only at one side of the fovea. An ILM flap is created to cover the macular hole. Comparison of retina vasculature in the areas of ILM peeling vs. no ILM peeling at 1 and 3 months after successful vitrectomy was performed. The study demonstrated lower density of vessels in the deep retinal plexus in the area where ILM was peeled as compared to the rest of the fovea. Visual acuity and central retinal thickness 1 month after surgery correlates with fovea avascular zone diameter in deep retinal layers at the same time point (P = 0.001). This study confirmed that ILM peeling might alter blood flow in deep retinal vessels below the peeling area in the early postoperative period. The area of the fovea avascular zone corresponds to functional results at the same time point.

  16. Displacement of foveal area toward optic disc after macular hole surgery with internal limiting membrane peeling.

    Science.gov (United States)

    Kawano, K; Ito, Y; Kondo, M; Ishikawa, K; Kachi, S; Ueno, S; Iguchi, Y; Terasaki, H

    2013-07-01

    To determine whether there is a displacement of the fovea toward the optic disc after successful macular hole (MH) surgery with internal limiting membrane (ILM) peeling. The medical records of 54 eyes of 53 patients that had undergone pars plana vitrectomy with ILM peeling and gas or air tamponade for an idiopathic MH were evaluated. Spectral-domain optical coherence tomography (OCT) had been performed before and >6 months after the surgery. The preoperative distances between the center of the MH and the optic disc (MH-OD), center of the MH and the bifurcation or crossing of retinal vessels (MH-RV) were measured in the OCT images. In addition, the postoperative distance between the center of the fovea and optic disc (F-OD) and the center of the fovea and the same bifurcation or crossing of retinal vessels (F-RV) were measured in the OCT images. The F-OD was 2.67±0.33 disc diameters (DD), which was significantly shorter than that of the MH-OD of 2.77±0.33 DD (Pdisplacement of the center of the macula toward the optic disc.

  17. 3. International conference on catalysis in membrane reactors

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1998-09-01

    The 3. International Conference on Catalysis in Membrane Reactors, Copenhagen, Denmark, is a continuation of the previous conferences held in Villeurbanne 1994 and Moscow 1996 and will deal with the rapid developments taking place within membranes with emphasis on membrane catalysis. The approx. 80 contributions in form of plenary lectures and posters discuss hydrogen production, methane reforming into syngas, selectivity and specificity of various membranes etc. The conference is organised by the Danish Catalytic Society under the Danish Society for Chemical Engineering. (EG)

  18. [Long-term outcome of vitrectomy combined with internal limiting membrane peeling for idiopathic macular holes].

    Science.gov (United States)

    Yamamoto, Kaori; Hori, Sadao

    2011-01-01

    To elucidate the long-term outcome of internal limiting membrane (ILM) peeling on visual function during vitrectomy for idiopathic macular holes using scanning laser ophthalmoscope (SLO) microperimetry. Prospective uncontrolled study. We studied 31 eyes (29 patients) with idiopathic macular holes. All patients underwent vitrectomy with ILM peeling. The SLO microperimetry was performed preoperatively, and once a year for 3 years postoperatively to detect scotomas in and around the macular holes, and both within and in close vicinity to the areas of ILM peeling. Closure of macular holes after one surgery was confirmed in all cases except for 2 with second surgery. The visual acuity by logarithmic minimum angle of resolution (logMAR) averaged 0.71 +/- 0.36 before surgery, 0.23 +/- 0.31 one year, 0.14 +/- 0.27 two years and 0.12 +/- 0.26 three years after surgery. There was significant improvement up to 2 years after the surgery. All scotomas detected before surgery in the holes, and 77.4% of those detected around the holes decreased gradually. No scotomas were detected in or around the area of ILM peeling either before or after surgery. ILM peeling in vitrectomy for idiopathic macular holes successfully improved visual acuity and did not influence retinal sensitivity in and around the area of ILM peeling. The scotomas detected in and around the holes before surgery gradually reduced or disappeared.

  19. IMPACT OF INTERNAL LIMITING MEMBRANE PEELING ON MACULAR HOLE REOPENING: A Systematic Review and Meta-Analysis.

    Science.gov (United States)

    Rahimy, Ehsan; McCannel, Colin A

    2016-04-01

    To assess the literature regarding macular hole reopening rates stratified by whether the internal limiting membrane (ILM) was peeled during vitrectomy surgery. Systematic review and meta-analysis of studies reporting on macular hole reopenings among previously surgically closed idiopathic macular holes. A comprehensive literature search using the National Library of Medicine PubMed interface was used to identify potentially eligible publications in English. The minimum mean follow-up period for reports to be included in this study was 12 months. Analysis was divided into eyes that underwent vitrectomy with and without ILM peeling. The primary outcome parameter was the proportion of macular hole reopenings among previously closed holes between the two groups. Secondary outcome parameters included duration from initial surgery to hole reopening and preoperative and postoperative best-corrected correct visual acuities among the non-ILM peeling and ILM peeling groups. A total of 50 publications reporting on 5,480 eyes met inclusion criteria and were assessed in this meta-analysis. The reopening rate without ILM peeling was 7.12% (125 of 1,756 eyes), compared with 1.18% (44 of 3,724 eyes) with ILM peeling (odds ratio: 0.16; 95% confidence interval: 0.11-0.22; Fisher's exact test: P peeling during macular hole surgery reduces the likelihood of macular hole reopening.

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

    Science.gov (United States)

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

    2015-01-01

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

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

    Directory of Open Access Journals (Sweden)

    Chun-Mei Deng

    2015-08-01

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

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

    DEFF Research Database (Denmark)

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

    2009-01-01

    AIM: To determine the effect of internal limiting membrane (ILM) peeling on anatomical and functional success rates in stage 2 and 3 idiopathic macular hole surgery (MHS). METHODS: Randomised clinical trial of stage 2 and 3 idiopathic macular hole without visible epiretinal fibrosis and with less...... than 1 year's duration of symptoms. Eyes were randomised to (1) vitrectomy alone without retinal surface manipulation, (2) vitrectomy plus 0.05% isotonic Indocyanine Green (ICG)-assisted ILM peeling or (3) vitrectomy plus 0.15% Trypan Blue (TB)-assisted ILM peeling. Main outcomes were hole closure...... after 3 and 12 months and best-corrected visual acuity after 12 months. RESULTS: 78 eyes were enrolled. Primary closure rates were significantly higher with ILM peeling than without peeling for both stage 2 holes (ICG peeling 100%, non-peeling 55%, p = 0.014) and for stage 3 holes (ICG peeling 91%, TB...

  3. Long-term outcomes of pars plana vitrectomy without internal limiting membrane peeling for optic disc pit maculopathy.

    Science.gov (United States)

    Avci, R; Yilmaz, S; Inan, U U; Kaderli, B; Kurt, M; Yalcinbayir, O; Yildiz, M; Yucel, A

    2013-12-01

    To evaluate the results of surgical treatment of maculopathy secondary to congenital optic pit anomaly with pars plana vitrectomy (PPV), endolaser to the temporal edge of the optic disc and C3F8 tamponade without internal limiting membrane (ILM) peeling. Thirteen eyes of 12 patients with serous macular detachment and/or macular retinoschisis secondary to congenital optic disc pit (ODP) were included in the study. All eyes underwent PPV, posterior hyaloid removal, endolaser photocoagulation on the temporal margin of the optic disc and 12% C3F8 gas tamponade. Anatomic success and functional outcome determined retrospectively by optical coherence tomography and measurement of best corrected visual acuity (BCVA), respectively were the main outcome parameters. Two lines or more improvement in BCVA was obtained in 11 eyes and 6 of these eyes had 20/40 or better BCVA at the final visit. Subretinal or intraretinal fluid was completely resorbed postoperatively in 12 eyes but a little intraretinal fluid persisted in one eye at the 16-month follow-up. Better visual improvement was observed in patients treated by earlier surgical intervention. PPV, C3F8 gas tamponade and endolaser to the optic disc margin without ILM peeling may yield favourable results in the treatment of ODP maculopathy.

  4. Increased Retinal Thinning after Combination of Internal Limiting Membrane Peeling and Silicone Oil Endotamponade in Proliferative Diabetic Retinopathy.

    Science.gov (United States)

    Kaneko, Hiroki; Matsuura, Toshiyuki; Takayama, Kei; Ito, Yasuki; Iwase, Takeshi; Ueno, Shinji; Nonobe, Norie; Yasuda, Shunsuke; Kataoka, Keiko; Terasaki, Hiroko

    2017-01-01

    The aim of this study was to examine the change in retinal thickness after vitrectomy with internal limiting membrane (ILM) peeling and/or silicone oil (SO) endotamponade in proliferative diabetic retinopathy (PDR). The actual amount and ratio of changes in the retinal thickness were calculated. Compared to control eyes in the ILM peeling (-)/SO (-) group, the central, superior inner, and temporal inner retina in the ILM peeling (+)/SO (-) group, the central and superior inner retina in the ILM peeling (-)/SO (+) group, and the central, inferior inner, temporal inner, and nasal inner retina in the ILM peeling (+)/SO (+) group showed a significant reduction of the retinal thickness. The central, superior inner, and temporal inner retina in the ILM peeling (+)/SO (-) group, the central and superior inner retina in the ILM peeling (-)/SO (+) group, and the central, superior inner, inferior inner, and temporal inner retina in the ILM peeling (+)/SO (+) group showed a significantly increased reduction rate of the retinal thickness compared to the control group. Macular retinal thinning in PDR was observed after ILM peeling and SO endotamponade, and it was increased by the combination of these 2 factors. © 2017 S. Karger AG, Basel.

  5. Retinal displacement toward optic disc after internal limiting membrane peeling for idiopathic macular hole.

    Science.gov (United States)

    Ishida, Masahiro; Ichikawa, Yoshikazu; Higashida, Rieko; Tsutsumi, Yorihisa; Ishikawa, Atsushi; Imamura, Yutaka

    2014-05-01

    To examine the retinal displacement following successful macular hole (MH) surgery with internal limiting membrane (ILM) peeling and gas tamponade, and to determine the correlation between the extent of displacement and the basal MH size. Retrospective, interventional, observational case series. The medical records of consecutive patients with an idiopathic MH that had undergone vitrectomy with ILM peeling and gas tamponade were studied. The distances between the optic disc and the intersection of 2 retinal vessels located nasal or temporal to the fovea were measured manually preoperatively (A), and 2 weeks and 1, 3, 6, and 12 months postoperatively (B), on the fundus autofluorescence or near-infrared images. The basal and minimum diameters of the MHs were measured in the spectral-domain optical coherence tomographic images. The correlations between the ratio of the retinal displacement (A - B/A) and basal diameters of the MHs were determined. Twenty-one eyes of 21 patients (9 men, mean age: 64.6 ± 8.4 years) were studied. Ten eyes (47.6%) had stage 2 MH, 9 eyes (42.9%) had stage 3 MH, and 2 eyes (9.5%) had stage 4 MH. The temporal retinal vessels were displaced 260.8 ± 145.8 μm toward the optic disc at 2 weeks postoperatively, which was significantly greater than the 91.1 ± 89.7 μm of the nasal retinal vessels (paired t test, P displacement in the temporal field at 2 weeks was significantly correlated with the basal diameter of the MH (Spearman's rank correlation coeffieient = -0.476, P = .033. The greater displacement of the temporal retina than the nasal retina toward the optic disc postoperatively suggests that the temporal retina is more flexible and can be retracted toward the optic disc during the MH closure. Copyright © 2014 Elsevier Inc. All rights reserved.

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

    Directory of Open Access Journals (Sweden)

    Yan Wu

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

  7. 3D visualization of the internal nanostructure of polyamide thin films in RO membranes

    KAUST Repository

    Pacheco Oreamuno, Federico

    2015-11-02

    The front and back surfaces of fully aromatic polyamide thin films isolated from reverse osmosis (RO) membranes were characterized by TEM, SEM and AFM. The front surfaces were relatively rough showing polyamide protuberances of different sizes and shapes; the back surfaces were all consistently smoother with very similar granular textures formed by polyamide nodules of 20–50 nm. Occasional pore openings of approximately the same size as the nodules were observed on the back surfaces. Because traditional microscopic imaging techniques provide limited information about the internal morphology of the thin films, TEM tomography was used to create detailed 3D visualizations that allowed the examination of any section of the thin film volume. These tomograms confirmed the existence of numerous voids within the thin films and revealed structural characteristics that support the water permeance difference between brackish water (BWRO) and seawater (SWRO) RO membranes. Consistent with a higher water permeance, the thin film of the BWRO membrane ESPA3 contained relatively more voids and thinner sections of polyamide than the SWRO membrane SWC3. According to the tomograms, most voids originate near the back surface and many extend all the way to the front surface shaping the polyamide protuberances. Although it is possible for the internal voids to be connected to the outside through the pore openings on the back surface, it was verified that some of these voids comprise nanobubbles that are completely encapsulated by polyamide. TEM tomography is a powerful technique for investigating the internal nanostructure of polyamide thin films. A comprehensive knowledge of the nanostructural distribution of voids and polyamide sections within the thin film may lead to a better understanding of mass transport and rejection mechanisms in RO membranes.

  8. 3D visualization of the internal nanostructure of polyamide thin films in RO membranes

    KAUST Repository

    Pacheco Oreamuno, Federico; Sougrat, Rachid; Reinhard, Martin; Leckie, James O.; Pinnau, Ingo

    2015-01-01

    The front and back surfaces of fully aromatic polyamide thin films isolated from reverse osmosis (RO) membranes were characterized by TEM, SEM and AFM. The front surfaces were relatively rough showing polyamide protuberances of different sizes and shapes; the back surfaces were all consistently smoother with very similar granular textures formed by polyamide nodules of 20–50 nm. Occasional pore openings of approximately the same size as the nodules were observed on the back surfaces. Because traditional microscopic imaging techniques provide limited information about the internal morphology of the thin films, TEM tomography was used to create detailed 3D visualizations that allowed the examination of any section of the thin film volume. These tomograms confirmed the existence of numerous voids within the thin films and revealed structural characteristics that support the water permeance difference between brackish water (BWRO) and seawater (SWRO) RO membranes. Consistent with a higher water permeance, the thin film of the BWRO membrane ESPA3 contained relatively more voids and thinner sections of polyamide than the SWRO membrane SWC3. According to the tomograms, most voids originate near the back surface and many extend all the way to the front surface shaping the polyamide protuberances. Although it is possible for the internal voids to be connected to the outside through the pore openings on the back surface, it was verified that some of these voids comprise nanobubbles that are completely encapsulated by polyamide. TEM tomography is a powerful technique for investigating the internal nanostructure of polyamide thin films. A comprehensive knowledge of the nanostructural distribution of voids and polyamide sections within the thin film may lead to a better understanding of mass transport and rejection mechanisms in RO membranes.

  9. [Effect of internal limiting membrane peeling on morpho-functional state of the retina in patients with proliferative diabetic retinopathy (preliminary report)].

    Science.gov (United States)

    Bikbov, M M; Fayzrakhmanov, R R; Kalanov, M R

    2018-01-01

    To compare morpho-functional parameters of retina during vitrectomy with and without internal limiting membrane (ILM) peeling in patients with proliferative diabetic retinopathy. The study included 55 patients (55 eyes) that had underwent vitreoretinal surgery in the setting of antivasoproliferative therapy for proliferative diabetic retinopathy. Patients of the 1 st group (n=27) underwent vitrectomy with silicone tamponade, 2 nd group (n=28) received similar treatment with the addition of ILM peeling. Three months after the treatment, all patients had silicone oil removed. Best Corrected Visual Acuity before treatment was 0.06±0.02 in both groups; after the treatment it improved to 0.1±0.05 (ppeeling during vitrectomy with following silicone oil tamponade eliminates the risk of ERM formation in patients with proliferative diabetic retinopathy in the follow-up period of up to 6-month and results in better morpho-functional parameters in comparison with patients who received similar treatment but without peeling.

  10. EFFECT OF INTERNAL LIMITING MEMBRANE PEELING DURING VITRECTOMY FOR DIABETIC MACULAR EDEMA: Systematic Review and Meta-analysis.

    Science.gov (United States)

    Nakajima, Takuya; Roggia, Murilo F; Noda, Yasuo; Ueta, Takashi

    2015-09-01

    To evaluate the effect of internal limiting membrane (ILM) peeling during vitrectomy for diabetic macular edema. MEDLINE, EMBASE, and CENTRAL were systematically reviewed. Eligible studies included randomized or nonrandomized studies that compared surgical outcomes of vitrectomy with or without ILM peeling for diabetic macular edema. The primary and secondary outcome measures were postoperative best-corrected visual acuity and central macular thickness. Meta-analysis on mean differences between vitrectomy with and without ILM peeling was performed using inverse variance method in random effects. Five studies (7 articles) with 741 patients were eligible for analysis. Superiority (95% confidence interval) in postoperative best-corrected visual acuity in ILM peeling group compared with nonpeeling group was 0.04 (-0.05 to 0.13) logMAR (equivalent to 2.0 ETDRS letters, P = 0.37), and superiority in best-corrected visual acuity change in ILM peeling group was 0.04 (-0.02 to 0.09) logMAR (equivalent to 2.0 ETDRS letters, P = 0.16). There was no significant difference in postoperative central macular thickness and central macular thickness reduction between the two groups. The visual acuity outcomes using pars plana vitrectomy with ILM peeling versus no ILM peeling were not significantly different. A larger randomized prospective study would be necessary to adequately address the effectiveness of ILM peeling on visual acuity outcomes.

  11. Vitrectomy with internal limiting membrane peeling vs no peeling for Macular Hole-induced Retinal Detachment (MHRD): a meta-analysis.

    Science.gov (United States)

    Su, Jing; Liu, Xinquan; Zheng, Lijun; Cui, Hongping

    2015-06-20

    we conducted our meta-analysis of published studies to assess existing evidence about the efficacy and safety of vitrectomy with ILM peeling vs. that of vitrectomy with no ILM peeling for Macular hole-induced retinal detachment. Databases, including Pubmed, Cochrane Library, Ovid, Web of Science, Wanfang and CNKI, were searched to identify studies comparing outcomes following vitrectomy with ILM peeling and that with no ILM peeling for macular hole-induced retinal detachment. The meta-analysis was performed by RevMan 5.1. Six comparative studies comprising 180 eyes were identified. It was indicated that the rate of retinal reattachment (Odds ratio (OR) = 3.03, 95 % Confidence interval (CI):1.35 to 6.78; P = 0.007) and macular hole closure (OR = 6.74, 95 % CI:3.26 to 13.93; P peeling than that in the group of vitrectomy with no ILM peeling. However, the improved BCVA (Weighted mean difference (WMD) = 0.14, 95 % CI: -0.20 to 0.47; P = 0.42) and the rate of postoperative complications were similar between the two groups. Vitrectomy with internal limiting membrane peeling is an efficient and safe procedure for macular hole-induced retinal detachment.

  12. Fovea sparing internal limiting membrane peeling using multiple parafoveal curvilinear peels for myopic foveoschisis: technique and outcome.

    Science.gov (United States)

    Jin, Haiying; Zhang, Qi; Zhao, Peiquan

    2016-10-18

    To introduce a modified surgical technique, the "parafoveal multiple curvelinear internal limiting membrane (ILM) peeling", to preserve epi-foveal ILM in myopic foveoschisis surgery. Consecutive patients with myopic foveoschisis were enrolled in the present prospective interventional case series. The surgeries were performed using transconjunctival 23-gauge system. The macular area was divided into quadrants. ILM was peeled off in a curvilinear manner centered around the site that was away from the central fovea in each quadrant. Shearing forces were used to control the direction to keep the peeling away from central fovea. ILM at central fovea of about 500 to 1000 μm was preserved by this technique. This technique was performed in 20 eyes of 20 consecutive patients. Epi-foveal ILM was successfully preserved in all cases using the technique. Patients were followed up for more than 12 months. The mean postoperative logMAR visual acuity improved from 1.67 ± 0.65 preoperatively to 1.15 ± 0.49 (P = 0.015; paired t-test). Postoperative OCT examinations showed that full-thickness macular holes (MHs) did not developed in any case. Central fovea thickness decreased from 910 ± 261 μm preoperatively to 125 ± 85 postoperatively (P = 0.001; paired t-test). Fovea sparing ILM peeling using multiple parafoveal curvilinear peels prevents the development of postoperative full-thickness MHs in eyes with myopic foveoschisis.

  13. On the thermal noise limit of cellular membranes.

    Science.gov (United States)

    Vincze, Gy; Szasz, N; Szasz, A

    2005-01-01

    Comparison of thermal noise limits and the effects of low frequency electromagnetic fields (LFEMF) on the cellular membrane have important implications for the study of bioelectro-magnetism in this regime. Over a decade ago, Weaver and Astumian developed a model to show that thermal noise can limit the efficacy of LFEMF. A recent report by Kaune [Kaune (2002) Bioelectromagnetics 23:622-628], however, contradicted their findings. Kaune assumes that the conductance noise current of cell membrane can be decomposed into two components, where one of them is identical regarding all segments (coherent), while the other is different (incoherent). Besides, this decomposition is not unequivocal and contradicts to the statistical independence of the segment noise currents, and therefore to the second law of thermodynamics as well. We suggest the procedure based on the method of symmetrical components, by the means of which we can re-interpret the result of Kaune in a correct way. 2004 Wiley-Liss, Inc.

  14. SURGICAL OUTCOMES AFTER INVERTED INTERNAL LIMITING MEMBRANE FLAP VERSUS CONVENTIONAL PEELING FOR VERY LARGE MACULAR HOLES.

    Science.gov (United States)

    Narayanan, Raja; Singh, Sumit R; Taylor, Stanford; Berrocal, Maria H; Chhablani, Jay; Tyagi, Mudit; Ohno-Matsui, Kyoko; Pappuru, Rajeev R; Apte, Rajendra S

    2018-04-23

    To evaluate the anatomical and visual outcomes of inverted flap technique of peeling of internal limiting membrane (ILM) versus standard peeling of ILM for macular holes of basal diameter more than 800 μm. Patients with very large idiopathic macular holes more than 800 μm in basal diameter (ranging from 243 μm to 840 μm in minimum diameter) were retrospectively included in the study. In Group A, 18 eyes of 18 patients underwent ILM peeling using the inverted flap technique. In Group B, 18 eyes of 18 patients underwent conventional ILM peeling. The primary endpoint was the rate of hole closure at 6 months after surgery. The secondary outcome measure was the change in best-corrected visual acuity at 6 months after surgery. There were no significant differences in ocular characteristics of the study groups at baseline except for the age distribution. Mean macular hole diameter was 1,162.8 ± 206.0 μm and 1,229.6 ± 228.1 μm in Group A and Group B, respectively. The hole closure rate was 88.9% (16/18) in Group A and 77.8% (14/18) in Group B (P = 0.66). The mean gain in best-corrected visual acuity was higher in Group A than in Group B (P = 0.12) at 6 months, but this was not statistically significant. There were no severe ocular adverse events in either group. In this multicenter series, inverted ILM flap technique did not lead to significantly higher anatomical closure rates than conventional ILM peeling in large macular holes more than 800 μm in diameter.

  15. Comparisons of foveal thickness and slope after macular hole surgery with and without internal limiting membrane peeling.

    Science.gov (United States)

    Ohta, Kouichi; Sato, Atsuko; Senda, Nami; Fukui, Emi

    2018-01-01

    We have shown that the foveal contour was asymmetrical after idiopathic macular hole (MH) closure by pars plana vitrectomy (PPV) with internal limiting membrane (ILM) peeling. The purpose of this study was to determine whether these morphological changes differ in eyes after PPV without ILM peeling. Ten eyes of 10 patients that underwent PPV without ILM peeling and 12 eyes of 11 patients with ILM peeling were studied. The MH in all eyes was 6 months after the surgery. The mean parafoveal retinal thickness in the non-peeled group was 367.1 µm in the nasal (N), 353.0 µm in the temporal (T), 366.9 µm in the superior (S), and 357.3 µm in the inferior (I) sectors. The T, S, and I sectors were significantly thicker than the corresponding sectors in the ILM peeled group ( p =0.0008, 0.003, and 0.03, respectively). The mean ganglion cell complex was thicker not only in the N sector but also in the T sector in the non-peeled group. The mean retinal slopes in the non-peeled group (N, 40.2°; T, 37.6°; S, 41.2°; I, 39.5°) were flatter than those in the peeled group (N, 52.3°; T, 43.6°; S, 50.8°; I, 51.9°; p =0.009, 0.09, 0.008, and 0.017, respectively). The symmetrical fovea after MH surgery in the non-ILM peeled eyes indicates that the asymmetrical fovea after ILM peeling was probably due to the ILM peeling.

  16. Vascular Displacement in Idiopathic Macular Hole after Single-layered Inverted Internal Limiting Membrane Flap Surgery.

    Science.gov (United States)

    Lee, Jae Jung; Lee, In Ho; Park, Keun Heung; Pak, Kang Yeun; Park, Sung Who; Byon, Ik Soo; Lee, Ji Eun

    2017-08-01

    To compare vascular displacement in the macula after surgical closure of idiopathic macular hole (MH) after single-layered inverted internal limiting membrane (ILM) flap technique and conventional ILM removal. This retrospective study included patients who underwent either vitrectomy and ILM removal only or vitrectomy with single-layered inverted ILM flap for idiopathic MH larger than 400 μm from 2012 to 2015. A customized program compared the positions of the retinal vessels in the macula between preoperative and postoperative photographs. En face images of 6 × 6 mm optical coherence tomography volume scans were registered to calculate the scale. Retinal vessel displacement was measured as a vector value by comparing its location in 16 sectors of a grid partitioned into eight sectors in two rings (inner, 2 to 4 mm; outer, 4 to 6 mm). The distance and angle of displacement were calculated as an average vector and were compared between the two groups for whole sectors, inner ring, outer ring, and for each sector. Twenty patients were included in the ILM flap group and 22 in the ILM removal group. There were no statistical differences between the groups for baseline characteristics. The average displacement in the ILM flap group and the ILM removal group was 56.6 μm at -3.4° and 64.9 μm at -2.7°, respectively, for the whole sectors (p = 0.900), 76.1 μm at -1.1° and 87.3 μm at -0.9° for the inner ring (p = 0.980), and 37.4 μm at -8.2° and 42.7 μm at -6.3° for the outer ring (p = 0.314). There was no statistical difference in the displacement of each of the sectors. Postoperative topographic changes showed no significant differences between the ILM flap and the ILM removal group for idiopathic MH. The single-layered ILM flap technique did not appear to cause additional displacement of the retinal vessels in the macula. © 2017 The Korean Ophthalmological Society

  17. Vitrectomy with internal limiting membrane peeling versus no peeling for idiopathic full-thickness macular hole.

    Science.gov (United States)

    Spiteri Cornish, Kurt; Lois, Noemi; Scott, Neil W; Burr, Jennifer; Cook, Jonathan; Boachie, Charles; Tadayoni, Ramin; la Cour, Morten; Christensen, Ulrik; Kwok, Alvin K H

    2014-03-01

    To determine whether internal limiting membrane (ILM) peeling improves anatomic and functional outcomes of full-thickness macular hole (FTMH) surgery when compared with the no-peeling technique. Systematic review and individual participant data (IPD) meta-analysis undertaken under the auspices of the Cochrane Eyes and Vision Group. Only randomized controlled trials (RCTs) were included. Patients with idiopathic stage 2, 3, and 4 FTMH undergoing vitrectomy with or without ILM peeling. Macular hole surgery, including vitrectomy and gas endotamponade with or without ILM peeling. Primary outcome was best-corrected distance visual acuity (BCdVA) at 6 months postoperatively. Secondary outcomes were BCdVA at 3 and 12 months; best-corrected near visual acuity (BCnVA) at 3, 6, and 12 months; primary (after a single surgery) and final (after >1 surgery) macular hole closure; need for additional surgical interventions; intraoperative and postoperative complications; patient-reported outcomes (PROs) (EuroQol-5D and Vision Function Questionnaire-25 scores at 6 months); and cost-effectiveness. Four RCTs were identified and included in the review. All RCTs were included in the meta-analysis; IPD were obtained from 3 of the 4 RCTs. No evidence of a difference in BCdVA at 6 months was detected (mean difference, -0.04; 95% confidence interval [CI], -0.12 to 0.03; P=0.27); however, there was evidence of a difference in BCdVA at 3 months favoring ILM peeling (mean difference, -0.09; 95% CI, -0.17 to-0.02; P=0.02). There was evidence of an effect favoring ILM peeling with regard to primary (odds ratio [OR], 9.27; 95% CI, 4.98-17.24; Ppeeling was found to be highly cost-effective. Available evidence supports ILM peeling as the treatment of choice for patients with idiopathic stage 2, 3, and 4 FTMH. Copyright © 2014 American Academy of Ophthalmology. Published by Elsevier Inc. All rights reserved.

  18. [Anatomical and functional results of macular hole surgery with internal limiting membrane peeling after 10-year follow-up].

    Science.gov (United States)

    Foveau, P; Conart, J-B; Hubert, I; Selton, J; Berrod, J-P

    2016-09-01

    To evaluate the anatomical and functional results of macular hole surgery with internal limiting membrane (ILM) peeling after 10 years follow-up. Monocentric retrospective study of patients who had undergone macular hole surgery between 2003 and 2005 in the Nancy University Medical Center and still followed in the department in 2014. All patients underwent pars plana vitrectomy and ILM peeling without staining. Clinical examination at ten years including determination of best-corrected visual acuity (BCVA), evaluation of quality of life and spectral domain optical coherence tomography was performed. Four men and six women with mean age of 64±8 years were included. The mean diameter of the MH was 395±133μm. The mean best corrected visual acuity improved significantly from 0.90±0.22 logMAR to 0.14±0.14 logMAR after 10 years with a satisfactory quality of life in 90 % of patients. The integrity of the IS/OS layer was preserved in 9 eyes. Inner retinal dimples located in the temporal quadrant related to ILM peeling initiation were observed in 8 eyes. No significant RNFL or ganglion cell complex changes were found compared to the contralateral eye. Macular hole surgery with ILM peeling in this series resulted in a visual acuity gain of 8 ETDRS lines and persistent improvement in quality of life after a 10-year follow-up. Copyright © 2016 Elsevier Masson SAS. All rights reserved.

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

    Directory of Open Access Journals (Sweden)

    Nadal J

    2015-05-01

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

  20. Internal limiting membrane flap transposition for surgical repair of macular holes in primary surgery and in persistent macular holes.

    Science.gov (United States)

    Leisser, Christoph; Hirnschall, Nino; Döller, Birgit; Varsits, Ralph; Ullrich, Marlies; Kefer, Katharina; Findl, Oliver

    2018-03-01

    Classical or temporal internal limiting membrane (ILM) flap transposition with air or gas tamponade are current trends with the potential to improve surgical results, especially in cases with large macular holes. A prospective case series included patients with idiopathic macular holes or persistent macular holes after 23-G pars plana vitrectomy (PPV) and ILM peeling with gas tamponade. In all patients, 23-G PPV and ILM peeling with ILM flap transposition with gas tamponade and postoperative face-down position was performed. In 7 of 9 eyes, temporal ILM flap transposition combined with pedicle ILM flap could be successfully performed and macular holes were closed in all eyes after surgery. The remaining 2 eyes were converted to pedicle ILM flap transposition with macular hole closure after surgery. Three eyes were scheduled as pedicle ILM flap transposition due to previous ILM peeling. In 2 of these eyes, the macular hole could be closed with pedicle ILM flap transposition. In 3 eyes, free ILM flap transposition was performed and in 2 of these eyes macular hole could be closed after surgery, whereas in 1 eye a second surgery, performed as pedicle ILM flap transposition, was performed and led to successful macular hole closure. Use of ILM flaps in surgical repair of macular hole surgery is a new option of treatment with excellent results independent of the diameter of macular holes. For patients with persistent macular holes, pedicle ILM flap transposition or free ILM flap transposition are surgical options.

  1. Outcomes of microscope-integrated intraoperative optical coherence tomography-guided center-sparing internal limiting membrane peeling for myopic traction maculopathy: a novel technique.

    Science.gov (United States)

    Kumar, Atul; Ravani, Raghav; Mehta, Aditi; Simakurthy, Sriram; Dhull, Chirakshi

    2017-07-04

    To evaluate the outcomes of pars plana vitrectomy (PPV) with microscope-integrated intraoperative optical coherence tomography (I-OCT)-guided traction removal and center-sparing internal limiting membrane (cs-ILM) peeling. Nine eyes with myopic traction maculopathy as diagnosed on SD-OCT underwent PPV with I-OCT-guided cs-ILM peeling and were evaluated prospectively for resolution of central macular thickness (CMT) and improvement in best-corrected visual acuity (BCVA), and complications, if any, were noted. All patients were followed up for more than 9 months. Resolution of the macular retinoschisis was seen in all nine eyes on SD-OCT. At 36 weeks, there was a significant improvement in mean BCVA from the preoperative BCVA (P = 0.0089) along with a reduction in the CMT from 569.77 ± 263.19 to 166.0 ± 43.91 um (P = 0.0039). None of the eyes showed worsening of BCVA or development of full-thickness macular hole in the intraoperative or follow-up period. PPV with I-OCT-guided cs-ILM peeling helps in complete removal of traction, resolution of retinoschisis and good functional recovery with low intraoperative and postoperative complications.

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

    Directory of Open Access Journals (Sweden)

    Hussain N

    2016-10-01

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

  3. HCIV-1 and Other Tailless Icosahedral Internal Membrane-Containing Viruses of the Family Sphaerolipoviridae

    Directory of Open Access Journals (Sweden)

    Tatiana A. Demina

    2017-02-01

    Full Text Available Members of the virus family Sphaerolipoviridae include both archaeal viruses and bacteriophages that possess a tailless icosahedral capsid with an internal membrane. The genera Alpha- and Betasphaerolipovirus comprise viruses that infect halophilic euryarchaea, whereas viruses of thermophilic Thermus bacteria belong to the genus Gammasphaerolipovirus. Both sequence-based and structural clustering of the major capsid proteins and ATPases of sphaerolipoviruses yield three distinct clades corresponding to these three genera. Conserved virion architectural principles observed in sphaerolipoviruses suggest that these viruses belong to the PRD1-adenovirus structural lineage. Here we focus on archaeal alphasphaerolipoviruses and their related putative proviruses. The highest sequence similarities among alphasphaerolipoviruses are observed in the core structural elements of their virions: the two major capsid proteins, the major membrane protein, and a putative packaging ATPase. A recently described tailless icosahedral haloarchaeal virus, Haloarcula californiae icosahedral virus 1 (HCIV-1, has a double-stranded DNA genome and an internal membrane lining the capsid. HCIV-1 shares significant similarities with the other tailless icosahedral internal membrane-containing haloarchaeal viruses of the family Sphaerolipoviridae. The proposal to include a new virus species, Haloarcula virus HCIV1, into the genus Alphasphaerolipovirus was submitted to the International Committee on Taxonomy of Viruses (ICTV in 2016.

  4. Efficacy of vitrectomy with triamcinolone assistance versus internal limiting membrane peeling for highly myopic macular hole retinal detachment.

    Science.gov (United States)

    Wei, Yong; Wang, Ningli; Zu, Zhongqiao; Bi, Chuncao; Wang, Huaizhou; Chen, Fenghua; Yang, Xingguang

    2013-06-01

    To compare the outcomes of pars plana vitrectomy (PPV) with or without the adjuvant surgical procedures: triamcinolone acetonide (TA) assistance and/or internal limiting membrane (ILM) peeling for the treatment of highly myopic macular hole retinal detachment (MHRD). Case-control study. Pars plana vitrectomy combined with 2 kinds of adjuvant surgical procedures were used on 96 highly myopic eyes with MHRD. These eyes were assigned to 4 groups randomly: Group 1, non-TA-assisted PPV and without ILM peeling; Group 2, non-TA-assisted PPV with ILM peeling; Group 3, TA-assisted PPV and without ILM peeling; Group 4, TA-assisted PPV with ILM peeling. Anatomical reattachment of the retina, macular hole closure, and best-corrected visual acuity were measured. The rates of both retinal reattachment and macular hole closure were higher in Group 2 (84.0 and 44.0%) and Group 3 (80.8 and 46.2%) than Group 1 (73.9 and 17.4%); however, there were no differences between Group 2 and Group 3 (P > 0.05). The rates of macular hole closure were extremely low in Group 1 and also in eyes with extreme long axial lengths (≥29.0 mm), "severe" chorioretinal atrophy, and posterior staphyloma. Pars plana vitrectomy with either TA assistance or ILM peeling was effective for the treatment of highly myopic MHRD. If you peel the ILM, adding TA does not affect closure rates; and if TA is used to visualize the vitreous, ILM peeling may not be necessary in MHRD. There was a lower anatomical success rate in MHRD with extreme long axial lengths, severe chorioretinal atrophy, and posterior staphyloma.

  5. Topology of membrane proteins-predictions, limitations and variations.

    Science.gov (United States)

    Tsirigos, Konstantinos D; Govindarajan, Sudha; Bassot, Claudio; Västermark, Åke; Lamb, John; Shu, Nanjiang; Elofsson, Arne

    2017-10-26

    Transmembrane proteins perform a variety of important biological functions necessary for the survival and growth of the cells. Membrane proteins are built up by transmembrane segments that span the lipid bilayer. The segments can either be in the form of hydrophobic alpha-helices or beta-sheets which create a barrel. A fundamental aspect of the structure of transmembrane proteins is the membrane topology, that is, the number of transmembrane segments, their position in the protein sequence and their orientation in the membrane. Along these lines, many predictive algorithms for the prediction of the topology of alpha-helical and beta-barrel transmembrane proteins exist. The newest algorithms obtain an accuracy close to 80% both for alpha-helical and beta-barrel transmembrane proteins. However, lately it has been shown that the simplified picture presented when describing a protein family by its topology is limited. To demonstrate this, we highlight examples where the topology is either not conserved in a protein superfamily or where the structure cannot be described solely by the topology of a protein. The prediction of these non-standard features from sequence alone was not successful until the recent revolutionary progress in 3D-structure prediction of proteins. Copyright © 2017 Elsevier Ltd. All rights reserved.

  6. Epiretinal membrane negative staining and double peeling in a single block with Brilliant Blue G.

    Science.gov (United States)

    Martins, David; Neves, Pedro

    2018-01-01

    To describe a surgical technique for combined peeling of epiretinal and internal limiting membranes. The authors present their procedure of choice for epiretinal membrane surgery: negative staining effect using Brilliant Blue G and single block removal of the epiretinal and internal limiting membranes in a single step. A total of 26 eyes were operated with the described technique. In all cases, the peeling was performed successfully and with no complications. Minimum postoperative follow-up was 12 months. There were no recurrences of epiretinal membranes. The ideal surgical approach for epiretinal membranes should attempt to reduce mechanical trauma, light exposure, and dye toxicity.

  7. Double-Skinned Forward Osmosis Membranes for Reducing Internal Concentration Polarization within the Porous Sublayer

    KAUST Repository

    Wang, Kai Yu

    2010-05-19

    A scheme to fabricate forward osmosis membranes comprising a highly porous sublayer sandwiched between two selective skin layers via phase inversion was proposed. One severe deficiency of existing composite and asymmetric membranes used in forward osmosis is the presence of unfavorable internal concentration polarization within the porous support layer that hinders both (i) separation (salt flux) and (ii) the performance (water flux). The double skin layers of the tailored membrane may mitigate the internal concentration polarization by preventing the salt and other solutes in the draw solution from penetrating into the membrane porous support. The prototype double-skinned cellulose acetate membrane displayed a water flux of 48.2 L·m-2·h -1 and lower reverse salt transport of 6.5 g·m -2·h-1 using 5.0 M MgCl2 as the draw solution in a forward osmosis process performed at 22 °C. This can be attributed to the effective salt rejection by the double skin layers and the low water transport resistance within the porous support layer. The prospects of utilizing the double-selective layer membranes may have potential application in forward osmosis for desalination. This study may help pave the way to improve the membrane design for the forward osmosis process. © 2010 American Chemical Society.

  8. Double-Skinned Forward Osmosis Membranes for Reducing Internal Concentration Polarization within the Porous Sublayer

    KAUST Repository

    Wang, Kai Yu; Ong, Rui Chin; Chung, Tai-Shung

    2010-01-01

    A scheme to fabricate forward osmosis membranes comprising a highly porous sublayer sandwiched between two selective skin layers via phase inversion was proposed. One severe deficiency of existing composite and asymmetric membranes used in forward osmosis is the presence of unfavorable internal concentration polarization within the porous support layer that hinders both (i) separation (salt flux) and (ii) the performance (water flux). The double skin layers of the tailored membrane may mitigate the internal concentration polarization by preventing the salt and other solutes in the draw solution from penetrating into the membrane porous support. The prototype double-skinned cellulose acetate membrane displayed a water flux of 48.2 L·m-2·h -1 and lower reverse salt transport of 6.5 g·m -2·h-1 using 5.0 M MgCl2 as the draw solution in a forward osmosis process performed at 22 °C. This can be attributed to the effective salt rejection by the double skin layers and the low water transport resistance within the porous support layer. The prospects of utilizing the double-selective layer membranes may have potential application in forward osmosis for desalination. This study may help pave the way to improve the membrane design for the forward osmosis process. © 2010 American Chemical Society.

  9. Internalization of components of the host cell plasma membrane during infection by Trypanosoma cruzi

    Directory of Open Access Journals (Sweden)

    Carvalho TMU

    1999-01-01

    Full Text Available Epimastigote and trypomastigote forms of Trypanosoma cruzi attach to the macrophage surface and are internalized with the formation of a membrane bounded vacuole, known as the parasitophorous vacuole (PV. In order to determine if components of the host cell membrane are internalized during formation of the PV we labeled the macrophage surface with fluorescent probes for proteins, lipids and sialic acid residues and then allowed the labeled cells to interact with the parasites. The interaction process was interrupted after 1 hr at 37ºC and the distribution of the probes analyzed by confocal laser scanning microscopy. During attachment of the parasites to the macrophage surface an intense labeling of the attachment regions was observed. Subsequently labeling of the membrane lining the parasitophorous vacuole containing epimastigote and trypomastigote forms was seen. Labeling was not uniform, with regions of intense and light or no labeling. The results obtained show that host cell membrane lipids, proteins and sialoglycoconjugates contribute to the formation of the membrane lining the PV containing epimastigote and trypomastigote T. cruzi forms. Lysosomes of the host cell may participate in the process of PV membrane formation.

  10. The Effects of Changing Membrane Compositions and Internal Electrolytes on the Respon of Potassium Ion Sensor

    OpenAIRE

    Ulianas, Alizar; Heng, Lee Yook

    2015-01-01

    A study on the changing of membrane compositions and internal solution towards the response potassium ion sensor was carried out. Potassium ion sensor based on photocured cross linking poly(n-butyl acrylate) membranes with varying composition of valinomycin (val), sodium tetrakis [3.5-bis(trifluoro-methyl) phenyl] borat (NaTFPB), types ion of internal solution were investigated. Effects of varying composition of val, NaTFPB, types and concentration of internal solution were observed on potass...

  11. Internal humidifying of PEM [Proton Exchange Membrane] fuel cells

    Energy Technology Data Exchange (ETDEWEB)

    Staschewski, D [Karlsruhe Research Center (FZK), Karlsruhe (Germany). Inst. for Neutron Physics and Reactor Technics

    1996-12-01

    Hydrogen fuel cells (FC) for vehicular traction should stand out for a car-specific lightweight design. As regards PEMFC systems containing proton exchange membranes, this quality can be considerably improved by introducing porous bipolar plates which are conditioned by a water loop and deliver hot humidifying water to the adjacent membrane-electrode assembly (MEA). According to the principle of internal humidification here indicated special fuel cells based on sintered fiber and powder graphite were manufactured at FZK on a semi-technical scale. Self-made Pt/C electrodes hotpressed onto Nafion resulted in currents up to 200 A with pure oxygen as oxidant, providing the precondition for detailed studies of turnover and drainage rates within a monocell test arrangement. (author)

  12. Plasma membrane cholesterol level and agonist-induced internalization of δ-opioid receptors; colocalization study with intracellular membrane markers of Rab family.

    Science.gov (United States)

    Brejchova, Jana; Vosahlikova, Miroslava; Roubalova, Lenka; Parenti, Marco; Mauri, Mario; Chernyavskiy, Oleksandr; Svoboda, Petr

    2016-08-01

    Decrease of cholesterol level in plasma membrane of living HEK293 cells transiently expressing FLAG-δ-OR by β-cyclodextrin (β-CDX) resulted in a slight internalization of δ-OR. Massive internalization of δ-OR induced by specific agonist DADLE was diminished in cholesterol-depleted cells. These results suggest that agonist-induced internalization of δ-OR, which has been traditionally attributed exclusively to clathrin-mediated pathway, proceeds at least partially via membrane domains. Identification of internalized pools of FLAG-δ-OR by colocalization studies with proteins of Rab family indicated the decreased presence of receptors in early endosomes (Rab5), late endosomes and lysosomes (Rab7) and fast recycling vesicles (Rab4). Slow type of recycling (Rab11) was unchanged by cholesterol depletion. As expected, agonist-induced internalization of oxytocin receptors was totally suppressed in β-CDX-treated cells. Determination of average fluorescence lifetime of TMA-DPH, the polar derivative of hydrophobic membrane probe diphenylhexatriene, in live cells by FLIM indicated a significant alteration of the overall PM structure which may be interpreted as an increased "water-accessible space" within PM area. Data obtained by studies of HEK293 cells transiently expressing FLAG-δ-OR by "antibody feeding" method were extended by analysis of the effect of cholesterol depletion on distribution of FLAG-δ-OR in sucrose density gradients prepared from HEK293 cells stably expressing FLAG-δ-OR. Major part of FLAG-δ-OR was co-localized with plasma membrane marker Na,K-ATPase and β-CDX treatment resulted in shift of PM fragments containing both FLAG-δ-OR and Na,K-ATPase to higher density. Thus, the decrease in content of the major lipid constituent of PM resulted in increased density of resulting PM fragments.

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

    Science.gov (United States)

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

    2014-03-01

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

  14. Picomolar detection limits with current-polarized Pb2+ ion-selective membranes.

    Science.gov (United States)

    Pergel, E; Gyurcsányi, R E; Tóth, K; Lindner, E

    2001-09-01

    Minor ion fluxes across ion-selective membranes bias submicromolar activity measurements with conventional ion-selective electrodes. When ion fluxes are balanced, the lower limit of detection is expected to be dramatically improved. As proof of principle, the flux of lead ions across an ETH 5435 ionophore-based lead-selective membrane was gradually compensated by applying a few nanoamperes of galvanostatic current. When the opposite ion fluxes were matched, and the undesirable leaching of primary ions was eliminated, Nernstian response down to 3 x 10(-12) M was achieved.

  15. Recruitment of human aquaporin 3 to internal membranes in the Plasmodium falciparum infected erythrocyte.

    Science.gov (United States)

    Bietz, Sven; Montilla, Irine; Külzer, Simone; Przyborski, Jude M; Lingelbach, Klaus

    2009-09-01

    The molecular mechanisms underlying the formation of the parasitophorous vacuolar membrane in Plasmodium falciparum infected erythrocytes are incompletely understood, and the protein composition of this membrane is still enigmatic. Although the differentiated mammalian erythrocyte lacks the machinery required for endocytosis, some reports have described a localisation of host cell membrane proteins at the parasitophorous vacuolar membrane. Aquaporin 3 is an abundant plasma membrane protein of various cells, including mammalian erythrocytes where it is found in distinct oligomeric states. Here we show that human aquaporin 3 is internalized into infected erythrocytes, presumably during or soon after invasion. It is integrated into the PVM where it is organized in novel oligomeric states which are not found in non-infected cells.

  16. HEMI-TEMPORAL INTERNAL LIMITING MEMBRANE PEELING IS AS EFFECTIVE AND SAFE AS CONVENTIONAL FULL PEELING FOR MACULAR HOLE SURGERY.

    Science.gov (United States)

    Shiono, Akira; Kogo, Jiro; Sasaki, Hiroki; Yomoda, Ryo; Jujo, Tatsuya; Tokuda, Naoto; Kitaoka, Yasushi; Takagi, Hitoshi

    2018-05-09

    To investigate the efficacy of hemi-temporal internal limiting membrane (ILM) peeling for idiopathic macular hole. The medical records of patients with macular holes who had undergone vitrectomy with ILM peeling were studied. Forty-two eyes with macular hole were divided into 2 groups based on surgical procedure (hemi-temporal ILM peeling [hemi group]: 15 eyes; 360° ILM peeling [360° group]: 27 eyes). The closure rates and distances between the optic disc and the intersection of two retinal vessels most closely located nasally or temporally to the macular hole were compared. The primary closure rates were not significantly different between the two groups (hemi group: 93.3%; 360° group: 92.5%, P = 0.92). The temporal retinal vessels in the hemi group were displaced 120.5 ± 102.0 µm toward the optic disc at 1 week postoperatively, which did not differ significantly from the 360° group (136.1 ± 106.1 µm) (P = 0.107). However, the nasal retinal vessels in the hemi group were displaced by 42.4 ± 42.9 µm at 1 week postoperatively, which was significantly less than the 90.1 ± 77.3 µm displacement seen in the 360° group (P = 0.040). Hemi-temporal ILM peeling may be preferable to 360° ILM peeling because of less displacement of the retina and greater safety.This is an open-access article distributed under the terms of the Creative Commons Attribution-Non Commercial-No Derivatives License 4.0 (CCBY-NC-ND), where it is permissible to download and share the work provided it is properly cited. The work cannot be changed in any way or used commercially without permission from the journal.

  17. Single-Molecule Fluorescence Studies of Membrane Transporters Using Total Internal Reflection Microscopy.

    Science.gov (United States)

    Goudsmits, Joris M H; van Oijen, Antoine M; Slotboom, Dirk J

    2017-01-01

    Cells are delineated by a lipid bilayer that physically separates the inside from the outer environment. Most polar, charged, or large molecules require proteins to reduce the energetic barrier for passage across the membrane and to achieve transport rates that are relevant for life. Here, we describe techniques to visualize the functioning of membrane transport proteins with fluorescent probes at the single-molecule level. First, we explain how to produce membrane-reconstituted transporters with fluorescent labels. Next, we detail the construction of a microfluidic flow cell to image immobilized proteoliposomes on a total internal reflection fluorescence microscope. We conclude by describing the methods that are needed to analyze fluorescence movies and obtain useful single-molecule data. © 2017 Elsevier Inc. All rights reserved.

  18. Effect of the perfluorodecalin residue on macular subretinal treated by internal limiting membrane peeling combined with 38G casing needle

    Directory of Open Access Journals (Sweden)

    Xiao-Bo Wang

    2014-11-01

    Full Text Available AIM: To observe the effect of the treatment to the perfluorodecalin residue on macular subretinal by internal limiting membrane(ILMpeeling combined with 38G casing needle.METHODS: Twenty-nine cases(29 eyesof retinal reattachment and with perfluorodecalin residual on the macular subretinal, selected in Xiamen Eye Center from January 2008 to October 2013, were divided into group A(14 cases, 14 eyesand group B(15 cases, 15 eyesrandomly. In group A, after removal of silicone oil, perfluorodecalin liquids at the macular subretinal directly were aspirated by 38G casing needle. In group B, after removal of silicone oil, ILM was dyed and peeled completely to the range of 4PD approximately. Then the perfluorodecalin liquids at the macular subretinal were aspirated by 38G casing needle. All cases of both groups were filled with filtered air. After 1wk, the case with macular hole found by OCT was exchanged by air-fluid and filled with 16% C3F8. The best corrected visual acuity(BCVAof two groups of patients was observed after 4, 8, 24wk. OCT was reviewed to observe whether there were perfluorodecalin residue on the macular subretinal, formation of macular hole and macular morphological changes, retinal detachment.RESULTS: BCVA was improved in both groups after 4, 8, 24wk. And the value of BCVA improvedin group B was better than that in group A(PCONCLUSION: ILM peeling combined with 38G casing needle can aspirate completely the perfluorodecalin residual on macular. There were not caused macular hole and retinal detachment. This method is an safe, effective and minimally invasive surgical technique to protect the macular function.

  19. Internal emitter limits for iodine, radium and radon daughters

    Energy Technology Data Exchange (ETDEWEB)

    Schlenker, R.A.

    1984-08-15

    This paper identifies some of the issues which arise in the consideration of the derivation of new limits on exposure to internal emitters. Basic and secondary radiation protection limits are discussed. Terms are defined and applied to the limitation of risk from stochastic effects. Non-stochastic data for specific internal emitters (/sup 131/I and the radium isotopes) are presented. Emphasis is placed on the quantitative aspects of the limit setting problem. 65 references, 2 figures, 12 tables.

  20. Internal emitter limits for iodine, radium and radon daughters

    International Nuclear Information System (INIS)

    Schlenker, R.A.

    1984-01-01

    This paper identifies some of the issues which arise in the consideration of the derivation of new limits on exposure to internal emitters. Basic and secondary radiation protection limits are discussed. Terms are defined and applied to the limitation of risk from stochastic effects. Non-stochastic data for specific internal emitters ( 131 I and the radium isotopes) are presented. Emphasis is placed on the quantitative aspects of the limit setting problem. 65 references, 2 figures, 12 tables

  1. A meta-analysis of vitrectomy with or without internal limiting membrane peeling for macular hole retinal detachment in the highly myopic eyes.

    Science.gov (United States)

    Gao, Xinxiao; Guo, Jia; Meng, Xin; Wang, Jun; Peng, Xiaoyan; Ikuno, Yasushi

    2016-06-13

    To evaluate the anatomical and visual outcomes by par plana vitrectomy with or without internal limiting membrane (ILM) peeling in highly myopic eyes with macular hole retinal detachment (MHRD). MEDLINE (Ovid, PubMed) and EMBASE were used for data collection up to September 30, 2015. The parameters of anatomical success, macular hole closure and improved best corrected visual acuity (BCVA) at or beyond 6 months after operation were assessed as the primary outcome measurement. The meta-analysis was performed with the fixed-effects model. Seven comparative analyses involving a total of 373 patients were included in the present meta-analysis. Statistically the pooled data showed significant relative risk (RR) in terms of primary reattachment between ILM peeling and non-peeling groups (RR, 1.19; 95 % CI, 1.04 to 1.36; P = 0.012). An effect favoring ILM peeling with regard to macular hole closure was also detected (RR, 1.71; 95 % CI, 1.20 to 2.43; P = 0.003). However, no statistically significant difference was found in the improved BCVA (logarithm of the minimum angle of resolution) at 6 months or more (95 % CI, -0.31 to 0.44; P = 0.738). There is no proved benefit of postoperative visual improvement. However, the available evidences from this study suggested a superiority of ILM peeling over no peeling for myopic patients with MHRD.

  2. External and internal limitations in amplitude-modulation processing

    DEFF Research Database (Denmark)

    Ewert, Stephan; Dau, Torsten

    2004-01-01

    Three experiments are presented to explore the relative role of "external" signal variability and "internal" resolution limitations of the auditory system in the detection and discrimination of amplitude modulations (AM). In the first experiment, AM-depth discrimination performance was determined......-filterbank models. The predictions revealed that AM-depth discrimination and AM detection are limited by a combination of the external signal variability and an internal "Weber-fraction" noise process....

  3. Knock-limited performance of several internal coolants

    Science.gov (United States)

    Bellman, Donald R; Evvard, John C

    1945-01-01

    The effect of internal cooling on the knock-limited performance of an-f-28 fuel was investigated in a CFR engine, and the following internal coolants were used: (1) water, (2), methyl alcohol-water mixture, (3) ammonia-methyl alcohol-water mixture, (4) monomethylamine-water mixture, (5) dimethylamine-water mixture, and (6) trimethylamine-water mixture. Tests were run at inlet-air temperatures of 150 degrees and 250 degrees F. to indicate the temperature sensitivity of the internal-coolant solutions.

  4. Internal hydration of a metal-transporting ATPase is controlled by membrane lateral pressure

    Energy Technology Data Exchange (ETDEWEB)

    Fahmy, Karim [Helmholtz-Zentrum Dresden-Rossendorf e.V., Dresden (Germany). Biophysics; Fischermeier, E. [Technische Univ. Dresden (Germany); Pospisil, P. [A.S.C. R., Prague (Czech Republic). J. Heyrovsky Inst. Physical Chemistry; Solioz, M. [Bern Univ. (Switzerland); Sayed, A.; Hof, M.

    2017-07-01

    The active transport of ions across biological mem branes requires their hydration shell to interact with the interior of membrane proteins. However, the influence of the external lipid phase on internal dielectric dynamics is hard to access by experiment. Using the octahelical transmembrane architecture of the copper-transporting P{sub 1B}-type ATPase from Legionella pneumophila (LpCopA) as a model structure, we have established the site-specific labeling of internal cysteines with a polarity-sensitive fluorophore. This enabled dipolar relaxation studies in a solubilized form of the protein and in its lipid-embedded state in nano-discs (NDs). Time-dependent fluorescence shifts revealed the site-specific hydration and dipole mobility around the conserved ion-binding motif. The spatial distribution of both features is shaped significantly and independently of each other by membrane lateral pressure.

  5. Internal hydration of a metal-transporting ATPase is controlled by membrane lateral pressure

    International Nuclear Information System (INIS)

    Fahmy, Karim; Pospisil, P.; Sayed, A.; Hof, M.

    2017-01-01

    The active transport of ions across biological mem branes requires their hydration shell to interact with the interior of membrane proteins. However, the influence of the external lipid phase on internal dielectric dynamics is hard to access by experiment. Using the octahelical transmembrane architecture of the copper-transporting P_1_B-type ATPase from Legionella pneumophila (LpCopA) as a model structure, we have established the site-specific labeling of internal cysteines with a polarity-sensitive fluorophore. This enabled dipolar relaxation studies in a solubilized form of the protein and in its lipid-embedded state in nano-discs (NDs). Time-dependent fluorescence shifts revealed the site-specific hydration and dipole mobility around the conserved ion-binding motif. The spatial distribution of both features is shaped significantly and independently of each other by membrane lateral pressure.

  6. Novel 'heavy' dyes for retinal membrane staining during macular surgery: multicenter clinical assessment

    NARCIS (Netherlands)

    Veckeneer, Marc; Mohr, Andreas; Alharthi, Essam; Azad, Rajvardhan; Bashshur, Ziad F.; Bertelli, Enrico; Bejjani, Riad A.; Bouassida, Brahim; Bourla, Dan; Crespo, Iñigo Corcóstegui; Fahed, Charbel; Fayyad, Faisal; Mura, Marco; Nawrocki, Jerzy; Rivett, Kelvin; Scharioth, Gabor B.; Shkvorchenko, Dmitry O.; Szurman, Peter; van Wijck, Hein; Wong, Ian Y.; Wong, David S. H.; Frank, Johannes; Oellerich, Silke; Bruinsma, Marieke; Melles, Gerrit R. J.

    2014-01-01

    Purpose: To evaluate the feasibility of two novel heavy' dye solutions for staining the internal limiting membrane (ILM) and epiretinal membranes (ERMs), without the need for a prior fluid-air exchange, during macular surgery. Methods: In this prospective nonrandomized multicenter cohort study, the

  7. 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.

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

    Science.gov (United States)

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

    2006-01-01

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

  9. Flow and fouling in membrane filters: Effects of membrane morphology

    Science.gov (United States)

    Sanaei, Pejman; Cummings, Linda J.

    2015-11-01

    Membrane filters are widely-used in microfiltration applications. Many types of filter membranes are produced commercially, for different filtration applications, but broadly speaking the requirements are to achieve fine control of separation, with low power consumption. The answer to this problem might seem obvious: select the membrane with the largest pore size and void fraction consistent with the separation requirements. However, membrane fouling (an inevitable consequence of successful filtration) is a complicated process, which depends on many parameters other than membrane pore size and void fraction; and which itself greatly affects the filtration process and membrane functionality. In this work we formulate mathematical models that can (i) account for the membrane internal morphology (internal structure, pore size & shape, etc.); (ii) fouling of membranes with specific morphology; and (iii) make some predictions as to what type of membrane morphology might offer optimum filtration performance.

  10. Internal noise sources limiting contrast sensitivity.

    Science.gov (United States)

    Silvestre, Daphné; Arleo, Angelo; Allard, Rémy

    2018-02-07

    Contrast sensitivity varies substantially as a function of spatial frequency and luminance intensity. The variation as a function of luminance intensity is well known and characterized by three laws that can be attributed to the impact of three internal noise sources: early spontaneous neural activity limiting contrast sensitivity at low luminance intensities (i.e. early noise responsible for the linear law), probabilistic photon absorption at intermediate luminance intensities (i.e. photon noise responsible for de Vries-Rose law) and late spontaneous neural activity at high luminance intensities (i.e. late noise responsible for Weber's law). The aim of this study was to characterize how the impact of these three internal noise sources vary with spatial frequency and determine which one is limiting contrast sensitivity as a function of luminance intensity and spatial frequency. To estimate the impact of the different internal noise sources, the current study used an external noise paradigm to factorize contrast sensitivity into equivalent input noise and calculation efficiency over a wide range of luminance intensities and spatial frequencies. The impact of early and late noise was found to drop linearly with spatial frequency, whereas the impact of photon noise rose with spatial frequency due to ocular factors.

  11. Extraction of Uranium with Amin as solvent and HCl as internal phase at membrane emulsion

    International Nuclear Information System (INIS)

    Ninik Bintarti, A.; Bambang-Edi-HB; Sudibyo, R.

    1996-01-01

    An extraction process of uranium by Tri-n-Actylamine(TOA) solution with kerosene as thinner and surfactant of Span-80 as emulgator to bend a membrane emulsion. HCI 0.01 N is used as an internal phase uranium in HNO 3 as feed and butanol is used to split the membrane. In the case of membrane, the result was 1 % vol. TOA and 5 % vol. Span-80, emulsification time was 30 minutes and 50 % vol. HCI 0.01 N. The product of an extraction was concentration of HNO 3 is 3 M. The time of extraction 20 minutes and uranium concentration in feed of 600 ppm will give distribution coefficient of membrane extraction was 5.830 and coefficient of stripping was 0.276

  12. Strategic analysis of International Forest Products Limited

    OpenAIRE

    Modesto, Robin M.

    2005-01-01

    International Forest Products Limited is a sawmilling company that produces softwood lumber for sale in domestic and international markets including the United States and Japan. Production facilities located in British Columbia, Washington and Oregon produce nearly 1.5 billion board feet of lumber annually. Timber is secured through Crown forest tenure holdings and external open market purchases. This paper includes: a strategic analysis of the firm; an industry analysis; a strategic fit anal...

  13. Plasma membrane cholesterol level and agonist-induced internalization of delta-opioid receptors; colocalization study with intracellular membrane markers of Rab family\

    Czech Academy of Sciences Publication Activity Database

    Brejchová, Jana; Vošahlíková, Miroslava; Roubalová, Lenka; Parenti, M.; Mauri, M.; Chernyavskiy, Oleksandr; Svoboda, Petr

    2016-01-01

    Roč. 48, č. 4 (2016), s. 375-396 ISSN 0145-479X R&D Projects: GA ČR(CZ) GAP207/12/0919 Institutional support: RVO:67985823 Keywords : cholesterol * plasma membrane * delta-opioid receptor * internalization * Rab proteins Subject RIV: CE - Biochemistry Impact factor: 2.576, year: 2016

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

    Directory of Open Access Journals (Sweden)

    Sato S

    2015-03-01

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

  15. Syndecan-4 Regulates Muscle Differentiation and Is Internalized from the Plasma Membrane during Myogenesis.

    Science.gov (United States)

    Rønning, Sissel B; Carlson, Cathrine R; Stang, Espen; Kolset, Svein O; Hollung, Kristin; Pedersen, Mona E

    2015-01-01

    The cell surface proteoglycan syndecan-4 has been reported to be crucial for muscle differentiation, but the molecular mechanisms still remain to be fully understood. During in vitro differentiation of bovine muscle cells immunocytochemical analyses showed strong labelling of syndecan-4 intracellularly, in close proximity with Golgi structures, in membranes of intracellular vesicles and finally, in the nuclear area including the nuclear envelope. Chase experiments showed that syndecan-4 was internalized from the plasma membrane during this process. Furthermore, when syndecan-4 was knocked down by siRNA more myotubes were formed, and the expression of myogenic transcription factors, β1-integrin and actin was influenced. However, when bovine muscle cells were treated with a cell-penetrating peptide containing the cytoplasmic region of syndecan-4, myoblast fusion and thus myotube formation was blocked, both in normal cells and in syndecan-4 knock down cells. Altogether this suggests that the cytoplasmic domain of syndecan-4 is important in regulation of myogenesis. The internalization of syndecan-4 from the plasma membrane during muscle differentiation and the nuclear localization of syndecan-4 in differentiated muscle cells may be part of this regulation, and is a novel aspect of syndecan biology which merits further studies.

  16. Syndecan-4 Regulates Muscle Differentiation and Is Internalized from the Plasma Membrane during Myogenesis.

    Directory of Open Access Journals (Sweden)

    Sissel B Rønning

    Full Text Available The cell surface proteoglycan syndecan-4 has been reported to be crucial for muscle differentiation, but the molecular mechanisms still remain to be fully understood. During in vitro differentiation of bovine muscle cells immunocytochemical analyses showed strong labelling of syndecan-4 intracellularly, in close proximity with Golgi structures, in membranes of intracellular vesicles and finally, in the nuclear area including the nuclear envelope. Chase experiments showed that syndecan-4 was internalized from the plasma membrane during this process. Furthermore, when syndecan-4 was knocked down by siRNA more myotubes were formed, and the expression of myogenic transcription factors, β1-integrin and actin was influenced. However, when bovine muscle cells were treated with a cell-penetrating peptide containing the cytoplasmic region of syndecan-4, myoblast fusion and thus myotube formation was blocked, both in normal cells and in syndecan-4 knock down cells. Altogether this suggests that the cytoplasmic domain of syndecan-4 is important in regulation of myogenesis. The internalization of syndecan-4 from the plasma membrane during muscle differentiation and the nuclear localization of syndecan-4 in differentiated muscle cells may be part of this regulation, and is a novel aspect of syndecan biology which merits further studies.

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

    Science.gov (United States)

    Adams, Michael C; Barbano, David M

    2016-01-01

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

  18. Long-term operation of oxygen-limiting membrane bioreactor (MBR) for the development of simultaneous partial nitrification, anammox and denitrification (SNAD) process.

    Science.gov (United States)

    Zhao, Chuanqi; Wang, Gang; Xu, Xiaochen; Yang, Yuesuo; Yang, Fenglin

    2017-07-18

    In this study, an oxygen-limiting membrane bioreactor (MBR) with recirculation of biogas for relieving membrane fouling was successfully operated to realize the simultaneous partial nitrification, anammox and denitrification (SNAD) process. The MBR operation was considered effective in the long-term test with total nitrogen (TN) and chemical oxygen demand (COD) removal efficiencies of 94.86% and 98.91%, respectively. Membrane fouling was significantly alleviated due to the recirculation of biogas and the membrane had been cleaned four times with a normal filtration period of 52 days. The co-existence of ammonia-oxidizing bacteria (AOB), anammox and denitrifying bacteria in MBR was confirmed by scanning electron microscopy (SEM) and fluorescence in situ hybridizations (FISH) analysis. Furthermore, AOB were found close to the granule surface, while denitrifying bacteria and anammox were in the deeper layer of granules. Potential in excellent TN and COD removal, operational stability and sustainability, as well as in alleviating membrane fouling is expected by using this oxygen-limiting MBR.

  19. Patterned ion exchange membranes for improved power production in microbial reverse-electrodialysis cells

    KAUST Repository

    Liu, Jia

    2014-12-01

    Power production in microbial reverse-electrodialysis cells (MRCs) can be limited by the internal resistance of the reverse electrodialysis stack. Typical MRC stacks use non-conductive spacers that block ion transport by the so-called spacer shadow effect. These spacers can be relatively thick compared to the membrane, and thus they increase internal stack resistance due to high solution (ohmic) resistance associated with a thick spacer. New types of patterned anion and cation exchange membranes were developed by casting membranes to create hemispherical protrusions on the membranes, enabling fluid flow between the membranes without the need for a non-conductive spacer. The use of the patterned membrane decreased the MRC stack resistance by ∼22 Ω, resulting in a 38% increase in power density from 2.50 ± 0.04 W m-2 (non-patterned membrane with a non-conductive spacer) to 3.44 ± 0.02 W m-2 (patterned membrane). The COD removal rate, coulombic efficiency, and energy efficiency of the MRC also increased using the patterned membranes compared to the non-patterned membranes. These results demonstrate that these patterned ion exchange membranes can be used to improve performance of an MRC. © 2014 Elsevier B.V. All rights reserved.

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

    KAUST Repository

    Yip, Ngai Yin

    2011-12-01

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

  1. Silver nanoparticles interact with the cell membrane and increase endothelial permeability by promoting VE-cadherin internalization

    Energy Technology Data Exchange (ETDEWEB)

    Sun, Xia; Shi, Junpeng; Zou, Xiaoyan; Wang, Chengcheng; Yang, Yi; Zhang, Hongwu, E-mail: hwzhang@iue.ac.cn

    2016-11-05

    Highlights: • Short-term exposure to AgNPs at low doses induces increase HUVECs monolayer permeability. • AgNPs interact with the cell membrane and increase endothelial permeability by promoting VE-Cadherin internalization. • Particle effect is a major factor leading to endothelial dysfunction. - Abstract: The toxicological risks of silver nanoparticles (AgNPs) have attracted widespread attention, and many studies have been published that have contributed to understanding AgNPs-induced toxicity. However, little attention has been paid to the low-dose effects of AgNPs and the related toxicological mechanism is still unclear. Here, we show that short-term exposure to AgNPs at low doses induces a substantial increase in human umbilical vein endothelial cells (HUVECs) monolayer permeability, whereas Ag ions at low doses do not induce an observable increase in monolayer permeability. This effect is independent of oxidative stress and apoptosis. Scanning electron microscopy confirms that AgNPs adhere to the cell membrane after 1 h exposure. Furthermore, adhesion of AgNPs to the cell membrane can trigger vascular endothelial (VE)-cadherin phosphorylation at Y658 followed by VE-cadherin internalization, which lead to the increase in endothelial monolayer permeability. Our data show that surface interactions of AgNPs with the cell membrane, in other words, the particle effect, is a major factor leading to endothelial dysfunction following low-dose and short-term exposure. Our findings will contribute to understanding the health effects and the toxicological mechanisms of AgNPs.

  2. Cost-effectiveness of internal limiting membrane peeling versus no peeling for patients with an idiopathic full-thickness macular hole: results from a randomised controlled trial.

    Science.gov (United States)

    Ternent, Laura; Vale, Luke; Boachie, Charles; Burr, Jennifer M; Lois, Noemi

    2012-03-01

    To determine whether internal limiting membrane (ILM) peeling is cost-effective compared with no peeling for patients with an idiopathic stage 2 or 3 full-thickness macular hole. A cost-effectiveness analysis was performed alongside a randomised controlled trial. 141 participants were randomly allocated to receive macular-hole surgery, with either ILM peeling or no peeling. Health-service resource use, costs and quality of life were calculated for each participant. The incremental cost per quality-adjusted life year (QALY) gained was calculated at 6 months. At 6 months, the total costs were on average higher (£424, 95% CI -182 to 1045) in the No Peel arm, primarily owing to the higher reoperation rate in the No Peel arm. The mean additional QALYs from ILM peel at 6 months were 0.002 (95% CI 0.01 to 0.013), adjusting for baseline EQ-5D and other minimisation factors. A mean incremental cost per QALY was not computed, as Peeling was on average less costly and slightly more effective. A stochastic analysis suggested that there was more than a 90% probability that Peeling would be cost-effective at a willingness-to-pay threshold of £20,000 per QALY. Although there is no evidence of a statistically significant difference in either costs or QALYs between macular hole surgery with or without ILM peeling, the balance of probabilities is that ILM Peeling is likely to be a cost-effective option for the treatment of macular holes. Further long-term follow-up data are needed to confirm these findings.

  3. Contaminant Permeation in the Ionomer-Membrane Water Processor (IWP) System

    Science.gov (United States)

    Kelsey, Laura K.; Finger, Barry W.; Pasadilla, Patrick; Perry, Jay

    2016-01-01

    The Ionomer-membrane Water Processor (IWP) is a patented membrane-distillation based urine brine water recovery system. The unique properties of the IWP membrane pair limit contaminant permeation from the brine to the recovered water and purge gas. A paper study was conducted to predict volatile trace contaminant permeation in the IWP system. Testing of a large-scale IWP Engineering Development Unit (EDU) with urine brine pretreated with the International Space Station (ISS) pretreatment formulation was then conducted to collect air and water samples for quality analysis. Distillate water quality and purge air GC-MS results are presented and compared to predictions, along with implications for the IWP brine processing system.

  4. Resultado funcional e índice macular em portadores de buraco macular submetidos à cirurgia com remoção da membrana limitante interna Functional outcome and macular index in macular hole patients who underwent surgery with internal limiting membrane removal

    Directory of Open Access Journals (Sweden)

    José Ricardo Diniz

    2008-04-01

    Full Text Available OBJETIVOS: Avaliar o resultado funcional e o índice macular dos portadores de buraco macular submetidos à cirurgia com remoção da membrana limitante interna. MÉTODOS: Quinze olhos de 15 pacientes com buraco macular estágios 2, 3 e 4 foram incluídos no estudo. Todos foram submetidos à cirurgia de buraco macular convencional com remoção da membrana limitante interna corada pelo azul de tripan. Melhor acuidade visual com correção e cortes transversais medidos por tomografia de coerência óptica (OCT foram avaliados no pré- e pós-operatório. O índice macular (razão entre a altura e base do buraco macular foi calculado e correlacionado com o diâmetro mínimo do buraco macular e o ganho de acuidade visual pós-operatória. RESULTADOS: Obteve-se fechamento do buraco macular em todos pacientes operados. Em 86,7%, houve ganho de pelo menos três linhas de visão. O índice macular demonstrou correlação negativa significante com o diâmetro mínimo (r=0,811. Não foi observada correlação significante entre o índice macular e o ganho de acuidade visual pós-operatória (r=0,351. CONCLUSÃO: Os resultados funcionais na cirurgia do buraco macular com remoção da membrana limitante interna foram bons neste grupo de pacientes. O índice macular demonstrou ser compatível com a configuração espacial do buraco macular, porém não foi preditor de resultados visuais.PURPOSE: To evaluate the functional outcome and macular index in patients with macular hole who underwent surgery with internal limiting membrane removal. METHODS: Fifteen eyes of 15 patients with idiopathic macular hole stages 2, 3 or 4 were enrolled in this study. All patients underwent conventional macular hole surgery with trypan blue staining to remove the internal limiting membrane. The best-corrected visual acuity and cross-sectional images of macular hole measured by optical coherence tomography (OCT were evaluated pre- and postoperatively. The macular hole index

  5. Chelating polymeric membranes

    KAUST Repository

    Peinemann, Klaus-Viktor; Villalobos Vazquez de la Parra, Luis Francisco; Hilke, Roland

    2015-01-01

    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.

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

    Directory of Open Access Journals (Sweden)

    A. Haddad

    2003-02-01

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

  7. Anchored but not internalized: shape dependent endocytosis of nanodiamond

    Science.gov (United States)

    Zhang, Bokai; Feng, Xi; Yin, Hang; Ge, Zhenpeng; Wang, Yanhuan; Chu, Zhiqin; Raabova, Helena; Vavra, Jan; Cigler, Petr; Liu, Renbao; Wang, Yi; Li, Quan

    2017-04-01

    Nanoparticle-cell interactions begin with the cellular uptake of the nanoparticles, a process that eventually determines their cellular fate. In the present work, we show that the morphological features of nanodiamonds (NDs) affect both the anchoring and internalization stages of their endocytosis. While a prickly ND (with sharp edges/corners) has no trouble of anchoring onto the plasma membrane, it suffers from difficult internalization afterwards. In comparison, the internalization of a round ND (obtained by selective etching of the prickly ND) is not limited by its lower anchoring amount and presents a much higher endocytosis amount. Molecular dynamics simulation and continuum modelling results suggest that the observed difference in the anchoring of round and prickly NDs likely results from the reduced contact surface area with the cell membrane of the former, while the energy penalty associated with membrane curvature generation, which is lower for a round ND, may explain its higher probability of the subsequent internalization.

  8. Miniaturization limitations of rotary internal combustion engines

    International Nuclear Information System (INIS)

    Wang, Wei; Zuo, Zhengxing; Liu, Jinxiang

    2016-01-01

    Highlights: • Developed a phenomenological model for rotary internal combustion engines. • Presented scaling laws for the performance of micro rotary engines. • Adiabatic walls can improve the cycle efficiency but result in higher charge leakage. • A lower compression ratio can increase the efficiency due to lower mass losses. • Presented possible minimum engine size of rotary internal combustion engines. - Abstract: With the rapid development of micro electro-mechanical devices, the demands for micro power generation systems have significantly increased in recent years. Traditional chemical batteries have energy densities much lower than hydrocarbon fuels, which makes internal-combustion-engine an attractive technological alternative to batteries. Micro rotary internal combustion engine has drawn great attractions due to its planar design, which is well-suited for fabrication in MEMS. In this paper, a phenomenological model considering heat transfer and mass leakage has been developed to investigate effects of engine speed, compression ratio, blow-by and heat transfer on the performance of micro rotary engine, which provide the guidelines for preliminary design of rotary engine. The lower possible miniaturization limits of rotary combustion engines are proposed.

  9. [Glaucoma and optic nerve drusen: Limitations of optic nerve head OCT].

    Science.gov (United States)

    Poli, M; Colange, J; Goutagny, B; Sellem, E

    2017-09-01

    Optic nerve head drusen are congenital calcium deposits located in the prelaminar section of the optic nerve head. Their association with visual field defects has been classically described, but the diagnosis of glaucoma is not easy in these cases of altered optic nerve head anatomy. We describe the case of a 67-year-old man with optic nerve head drusen complicated by glaucoma, which was confirmed by visual field and OCT examination of the peripapillary retinal nerve fiber layer (RNFL), but the measurement of the minimum distance between the Bruch membrane opening and the internal limiting membrane (minimum rim width, BMO-MRW) by OCT was normal. OCT of the BMO-MRW is a new diagnostic tool for glaucoma. Superficial optic nerve head drusen, which are found between the internal limiting membrane and the Bruch's membrane opening, overestimate the value of this parameter. BMO-MRW measurement is not adapted to cases of optic nerve head drusen and can cause false-negative results for this parameter, and the diagnosis of glaucoma in this case should be based on other parameters such as the presence of a fascicular defect in the retinal nerve fibers, RNFL or macular ganglion cell complex thinning, as well as visual field data. Copyright © 2017 Elsevier Masson SAS. All rights reserved.

  10. [Functional and Anatomic Outcomes of Primary and Secondary Internal Limiting Membrane Transplantation in Large and Persistent Macular Holes].

    Science.gov (United States)

    Hess, Jelka A; Michels, Stephan; Becker, Matthias D

    2017-11-20

    Background The gold standard therapy for full-thickness macular holes (FTMH) is vitrectomy (PPV) with peeling of the internal limiting membrane (ILM), gas tamponade of the vitreous cavity and postoperative face-down positioning. Nevertheless, eyes with large macular holes (> 400 µm) and surgical failures remain difficult to manage. Recently, ILM transplantation (ILM-TX) techniques were developed with acceptable results, advocating different mechanisms of hole closure: in such a setting, the ILM could serve as a scaffold for neuronal tissue in the pedicle ILM flap technique or the ILM could induce a contraction of the FTMH rims through shrinking of a folded ILM plug. Patients/Material and Methods This retrospective study evaluates the functional and anatomic outcomes following ILM-TX for large FTMH and failed FMTH surgery. Large holes (group 1) were treated by the pedicle flap and the plug technique. Persistent holes following vitrectomy and ILM peeling (group 2) were treated with the plug technique. All ILM-TX were performed under perfluorocarbon liquid (PFCL) with a subsequent silicone oil tamponade. Results In group 1 (6 eyes), three eyes had a free ILM graft and three eyes underwent a pedunculated ILM-TX. The mean best corrected visual acuity (BCVA, LogMar) before primary ILM-TX was 1.18 ± 0.54 with a mean initial hole size of 681 ± 106 µm and a photoreceptor defect (PRD) of 1829 ± 474 µm. Five of six eyes showed a postoperative anatomical macular hole closure (83%). The mean BCVA after a mean follow-up of 9.3 ± 5.1 months was 0.83 ± 0.31 after a free ILM graft and 0.95 ± 0.79 after a pedunculated ILM flap. The PRD reduced to 1781 ± 713 µm after a free ILM graft and 1148 ± 378 µm after a pedunculated ILM flap. In group 2 (7 eyes), all patients had failed initial macular hole surgery closure. Prior to free ILM-TX BCVA was 1.05 ± 0.41, the hole size was 433 ± 183 µm and PRD was 2012 ± 718

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

    Science.gov (United States)

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

    2017-05-01

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

  12. Drinking water treatment using a submerged internal-circulation membrane coagulation reactor coupled with permanganate oxidation.

    Science.gov (United States)

    Zhang, Zhongguo; Liu, Dan; Qian, Yu; Wu, Yue; He, Peiran; Liang, Shuang; Fu, Xiaozheng; Li, Jiding; Ye, Changqing

    2017-06-01

    A submerged internal circulating membrane coagulation reactor (MCR) was used to treat surface water to produce drinking water. Polyaluminum chloride (PACl) was used as coagulant, and a hydrophilic polyvinylidene fluoride (PVDF) submerged hollow fiber microfiltration membrane was employed. The influences of trans-membrane pressure (TMP), zeta potential (ZP) of the suspended particles in raw water, and KMnO 4 dosing on water flux and the removal of turbidity and organic matter were systematically investigated. Continuous bench-scale experiments showed that the permeate quality of the MCR satisfied the requirement for a centralized water supply, according to the Standards for Drinking Water Quality of China (GB 5749-2006), as evaluated by turbidity (<1 NTU) and total organic carbon (TOC) (<5mg/L) measurements. Besides water flux, the removal of turbidity, TOC and dissolved organic carbon (DOC) in the raw water also increased with increasing TMP in the range of 0.01-0.05MPa. High ZP induced by PACl, such as 5-9mV, led to an increase in the number of fine and total particles in the MCR, and consequently caused serious membrane fouling and high permeate turbidity. However, the removal of TOC and DOC increased with increasing ZP. A slightly positive ZP, such as 1-2mV, corresponding to charge neutralization coagulation, was favorable for membrane fouling control. Moreover, dosing with KMnO 4 could further improve the removal of turbidity and DOC, thereby mitigating membrane fouling. The results are helpful for the application of the MCR in producing drinking water and also beneficial to the research and application of other coagulation and membrane separation hybrid processes. Copyright © 2016. Published by Elsevier B.V.

  13. Spontaneous Absorption of Extensive Subinternal Limiting Membrane Hemorrhage in Shaken Baby Syndrome

    Directory of Open Access Journals (Sweden)

    Tatiana Tarules Azzi

    2014-01-01

    Full Text Available The Shaken Baby Syndrome (SBS is characterized by subdural hematomas (SH, retinal hemorrhages (RH, and multiple fractures of long bones without external evidence of head trauma. Subinternal limiting membrane (ILM hemorrhage, also known as macular schisis, is a characteristic finding of this entity. There is no guideline on the right time to indicate surgical treatment. This report describes an abused child with massive sub-ILM hemorrhage, which showed spontaneous absorption after less than two months of follow-up. Due to the possible spontaneous resolution, we suggest an initial conservative treatment in cases of sub-ILM hemorrhage related to SBS.

  14. Dynamics of Receptor-Mediated Nanoparticle Internalization into Endothelial Cells

    Science.gov (United States)

    Gonzalez-Rodriguez, David; Barakat, Abdul I.

    2015-01-01

    Nanoparticles offer a promising medical tool for targeted drug delivery, for example to treat inflamed endothelial cells during the development of atherosclerosis. To inform the design of such therapeutic strategies, we develop a computational model of nanoparticle internalization into endothelial cells, where internalization is driven by receptor-ligand binding and limited by the deformation of the cell membrane and cytoplasm. We specifically consider the case of nanoparticles targeted against ICAM-1 receptors, of relevance for treating atherosclerosis. The model computes the kinetics of the internalization process, the dynamics of binding, and the distribution of stresses exerted between the nanoparticle and the cell membrane. The model predicts the existence of an optimal nanoparticle size for fastest internalization, consistent with experimental observations, as well as the role of bond characteristics, local cell mechanical properties, and external forces in the nanoparticle internalization process. PMID:25901833

  15. Membrane order in the plasma membrane and endocytic recycling compartment.

    Science.gov (United States)

    Iaea, David B; Maxfield, Frederick R

    2017-01-01

    The cholesterol content of membranes plays an important role in organizing membranes for signal transduction and protein trafficking as well as in modulating the biophysical properties of membranes. While the properties of model or isolated membranes have been extensively studied, there has been little evaluation of internal membranes in living cells. Here, we use a Nile Red based probe, NR12S, and ratiometric live cell imaging, to analyze the membrane order of the plasma membrane and endocytic recycling compartment. We find that after a brief incubation to allow endocytosis, NR12S is distributed between the plasma membrane and the endocytic recycling compartment. The NR12S reports that the endocytic recycling compartment is more highly ordered than the plasma membrane. We also find that the plasma membrane and the endocytic recycling compartment are differentially affected by altering cellular cholesterol levels. The membrane order of the plasma membrane, but not the endocytic recycling compartment, is altered significantly when cellular cholesterol content is increased or decreased by 20%. These results demonstrate that changes in cellular cholesterol differentially alter membrane order within different organelles.

  16. G-protein signaling leverages subunit-dependent membrane affinity to differentially control βγ translocation to intracellular membranes.

    Science.gov (United States)

    O'Neill, Patrick R; Karunarathne, W K Ajith; Kalyanaraman, Vani; Silvius, John R; Gautam, N

    2012-12-18

    Activation of G-protein heterotrimers by receptors at the plasma membrane stimulates βγ-complex dissociation from the α-subunit and translocation to internal membranes. This intermembrane movement of lipid-modified proteins is a fundamental but poorly understood feature of cell signaling. The differential translocation of G-protein βγ-subunit types provides a valuable experimental model to examine the movement of signaling proteins between membranes in a living cell. We used live cell imaging, mathematical modeling, and in vitro measurements of lipidated fluorescent peptide dissociation from vesicles to determine the mechanistic basis of the intermembrane movement and identify the interactions responsible for differential translocation kinetics in this family of evolutionarily conserved proteins. We found that the reversible translocation is mediated by the limited affinity of the βγ-subunits for membranes. The differential kinetics of the βγ-subunit types are determined by variations among a set of basic and hydrophobic residues in the γ-subunit types. G-protein signaling thus leverages the wide variation in membrane dissociation rates among different γ-subunit types to differentially control βγ-translocation kinetics in response to receptor activation. The conservation of primary structures of γ-subunits across mammalian species suggests that there can be evolutionary selection for primary structures that confer specific membrane-binding affinities and consequent rates of intermembrane movement.

  17. Mechanical ventilation management during extracorporeal membrane oxygenation for acute respiratory distress syndrome: a retrospective international multicenter study.

    Science.gov (United States)

    Schmidt, Matthieu; Stewart, Claire; Bailey, Michael; Nieszkowska, Ania; Kelly, Joshua; Murphy, Lorna; Pilcher, David; Cooper, D James; Scheinkestel, Carlos; Pellegrino, Vincent; Forrest, Paul; Combes, Alain; Hodgson, Carol

    2015-03-01

    To describe mechanical ventilation settings in adult patients treated for an acute respiratory distress syndrome with extracorporeal membrane oxygenation and assess the potential impact of mechanical ventilation settings on ICU mortality. Retrospective observational study. Three international high-volume extracorporeal membrane oxygenation centers. A total of 168 patients treated with extracorporeal membrane oxygenation for severe acute respiratory distress syndrome from January 2007 to January 2013. We analyzed the association between mechanical ventilation settings (i.e. plateau pressure, tidal volume, and positive end-expiratory pressure) on ICU mortality using multivariable logistic regression model and Cox-proportional hazards model. We obtained detailed demographic, clinical, daily mechanical ventilation settings and ICU outcome data. One hundred sixty-eight patients (41 ± 14 years old; PaO2/FIO2 67 ± 19 mm Hg) fulfilled our inclusion criteria. Median duration of extracorporeal membrane oxygenation and ICU stay were 10 days (6-18 d) and 28 days (16-42 d), respectively. Lower positive end-expiratory pressure levels and significantly lower plateau pressures during extracorporeal membrane oxygenation were used in the French center than in both Australian centers (23.9 ± 1.4 vs 27.6 ± 3.7 and 27.8 ± 3.6; p Protective mechanical ventilation strategies were routinely used in high-volume extracorporeal membrane oxygenation centers. However, higher positive end-expiratory pressure levels during the first 3 days on extracorporeal membrane oxygenation support were independently associated with improved survival. Further prospective trials on the optimal mechanical ventilation strategy during extracorporeal membrane oxygenation support are warranted.

  18. Contribution of NADPH Oxidase to Membrane CD38 Internalization and Activation in Coronary Arterial Myocytes

    Science.gov (United States)

    Xu, Ming; Li, Xiao-Xue; Ritter, Joseph K.; Abais, Justine M.; Zhang, Yang; Li, Pin-Lan

    2013-01-01

    The CD38-ADP-ribosylcyclase-mediated Ca2+ signaling pathway importantly contributes to the vasomotor response in different arteries. Although there is evidence indicating that the activation of CD38-ADP-ribosylcyclase is associated with CD38 internalization, the molecular mechanism mediating CD38 internalization and consequent activation in response to a variety of physiological and pathological stimuli remains poorly understood. Recent studies have shown that CD38 may sense redox signals and is thereby activated to produce cellular response and that the NADPH oxidase isoform, NOX1, is a major resource to produce superoxide (O2 ·−) in coronary arterial myocytes (CAMs) in response to muscarinic receptor agonist, which uses CD38-ADP-ribosylcyclase signaling pathway to exert its action in these CAMs. These findings led us hypothesize that NOX1-derived O2 ·− serves in an autocrine fashion to enhance CD38 internalization, leading to redox activation of CD38-ADP-ribosylcyclase activity in mouse CAMs. To test this hypothesis, confocal microscopy, flow cytometry and a membrane protein biotinylation assay were used in the present study. We first demonstrated that CD38 internalization induced by endothelin-1 (ET-1) was inhibited by silencing of NOX1 gene, but not NOX4 gene. Correspondingly, NOX1 gene silencing abolished ET-1-induced O2 ·− production and increased CD38-ADP-ribosylcyclase activity in CAMs, while activation of NOX1 by overexpression of Rac1 or Vav2 or administration of exogenous O2 ·− significantly increased CD38 internalization in CAMs. Lastly, ET-1 was found to markedly increase membrane raft clustering as shown by increased colocalization of cholera toxin-B with CD38 and NOX1. Taken together, these results provide direct evidence that Rac1-NOX1-dependent O2 ·− production mediates CD38 internalization in CAMs, which may represent an important mechanism linking receptor activation with CD38 activity in these cells. PMID:23940720

  19. 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...... flux increased with rotation speed and distance from membrane center as an effect of shear. Further, the limiting flux decreased with increasing sludge concentration. A model was developed to link the sludge concentration and shear stress to the limiting flux. The model was able to simulate the effect...... of shear stress and sludge concentration on the limiting flux. The model was developed by calculating the shear rate at laminar flow regime at different rotation speeds and radii on the membrane. Furthermore, through the shear rate and shear stress, the non-Newtonian behavior of MBR sludge was addressed...

  20. Well-constructed cellulose acetate membranes for forward osmosis: Minimized internal concentration polarization with an ultra-thin selective layer

    KAUST Repository

    Zhang, Sui

    2010-09-01

    The design and engineering of membrane structure that produces low salt leakage and minimized internal concentration polarization (ICP) in forward osmosis (FO) processes have been explored in this work. The fundamentals of phase inversion of cellulose acetate (CA) regarding the formation of an ultra-thin selective layer at the bottom interface of polymer and casting substrate were investigated by using substrates with different hydrophilicity. An in-depth understanding of membrane structure and pore size distribution has been elucidated with field emission scanning electronic microscopy (FESEM) and positron annihilation spectroscopy (PAS). A double dense-layer structure is formed when glass plate is used as the casting substrate and water as the coagulant. The thickness of the ultra-thin bottom layer resulted from hydrophilic-hydrophilic interaction is identified to be around 95nm, while a fully porous, open-cell structure is formed in the middle support layer due to spinodal decomposition. Consequently, the membrane shows low salt leakage with mitigated ICP in the FO process for seawater desalination. The structural parameter (St) of the membrane is analyzed by modeling water flux using the theory that considers both external concentration polarization (ECP) and ICP, and the St value of the double dense-layer membrane is much smaller than those reported in literatures. Furthermore, the effects of an intermediate immersion into a solvent/water mixed bath prior to complete immersion in water on membrane formation have been studied. The resultant membranes may have a single dense layer with an even lower St value. A comparison of fouling behavior in a simple FO-membrane bioreactor (MBR) system is evaluated for these two types of membranes. The double dense-layer membrane shows a less fouling propensity. This study may help pave the way to improve the membrane design for new-generation FO membranes. © 2010 Elsevier B.V.

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2017-03-18

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

  2. Degradation of Polypropylene Membranes Applied in Membrane Distillation Crystallizer

    Directory of Open Access Journals (Sweden)

    Marek Gryta

    2016-03-01

    Full Text Available The studies on the resistance to degradation of capillary polypropylene membranes assembled in a membrane crystallizer were performed. The supersaturation state of salt was achieved by evaporation of water from the NaCl saturated solutions using membrane distillation process. A high feed temperature (363 K was used in order to enhance the degradation effects and to shorten the test times. Salt crystallization was carried out by the application of batch or fluidized bed crystallizer. A significant membrane scaling was observed regardless of the method of realized crystallization. The SEM-EDS, DSC, and FTIR methods were used for investigations of polypropylene degradation. The salt crystallization onto the membrane surface accelerated polypropylene degradation. Due to a polymer degradation, the presence of carbonyl groups on the membranes’ surface was identified. Besides the changes in the chemical structure a significant mechanical damage of the membranes, mainly caused by the internal scaling, was also found. As a result, the membranes were severely damaged after 150 h of process operation. A high level of salt rejection was maintained despite damage to the external membrane surface.

  3. Mechanical ventilation during extracorporeal membrane oxygenation. An international survey.

    Science.gov (United States)

    Marhong, Jonathan D; Telesnicki, Teagan; Munshi, Laveena; Del Sorbo, Lorenzo; Detsky, Michael; Fan, Eddy

    2014-07-01

    In patients with severe, acute respiratory failure undergoing venovenous extracorporeal membrane oxygenation (VV-ECMO), the optimal strategy for mechanical ventilation is unclear. Our objective was to describe ventilation practices used in centers registered with the Extracorporeal Life Support Organization (ELSO). We conducted an international cross-sectional survey of medical directors and ECMO program coordinators from all ELSO-registered centers. The survey was distributed using a commercial website that collected information on center characteristics, the presence of a mechanical ventilator protocol, ventilator settings, and weaning practices. E-mails were sent out to medical directors or coordinators at each ELSO center and their responses were pooled for analysis. We analyzed 141 (50%) individual responses from the 283 centers contacted across 28 countries. Only 27% of centers reported having an explicit mechanical ventilation protocol for ECMO patients. The majority of these centers (77%) reported "lung rest" to be the primary goal of mechanical ventilation, whereas 9% reported "lung recruitment" to be their ventilation strategy. A tidal volume of 6 ml/kg or less was targeted by 76% of respondents, and 58% targeted a positive end-expiratory pressure of 6-10 cm H2O while ventilating patients on VV-ECMO. Centers prioritized weaning VV-ECMO before mechanical ventilation. Although ventilation practices in patients supported by VV-ECMO vary across ELSO centers internationally, the majority of centers used a strategy that targeted lung-protective thresholds and prioritized weaning VV-ECMO over mechanical ventilation.

  4. Induced membrane technique combined with two-stage internal fixation for the treatment of tibial osteomyelitis defects.

    Science.gov (United States)

    Luo, Fei; Wang, Xiaohua; Wang, Shulin; Fu, Jingshu; Xie, Zhao

    2017-07-01

    The purpose of this study was to observe the effects of induced membrane technique combined with two-stage internal fixation in the treatment of tibial osteomyelitis defects. A retrospective analyses for 67 cases of tibialosteomyelitis defects were admitted to our department between September 2012 to February 2015, which were treated with induced membrane technique. At the first stage, implanted with a PMMA cement spacer in the defects after radical debridement and fixed with reconstructive locked plate. Bone grafting and exchanged the plate with intramedullary nail at the second stage. In current study, all patients were followed up for 18-35 months. Sixty-six patients achieved bone union with the average radiographic and clinical healing times of 5.55±2.19 and 7.45±1.69months, respectively. Seven patients required a second debridement before grafting, while four patients experienced a recurrence of infection or a relapse following second stage treatment. Twelve patients experienced either knee or ankle dysfunctions and 2 patients faced delayed wound healing. Donor site complications includes pain and infection were found in 7 and 3 patients, respectively with delayed stress fracture in 1 patient only. Induced membrane technique for the treatment of tibial osteomyelitis defects, seems a reliable method. The use of reconstructive locked plate as a temporary internal fixation at the first stage and exchanged with intramedullary nail at the second stage, potentially achieves good clinical efficacy. Care should be taken to restore the joint function especially in distal tibia. Copyright © 2017 Elsevier Ltd. All rights reserved.

  5. The Plasma Membrane Sialidase NEU3 Regulates the Malignancy of Renal Carcinoma Cells by Controlling β1 Integrin Internalization and Recycling*

    Science.gov (United States)

    Tringali, Cristina; Lupo, Barbara; Silvestri, Ilaria; Papini, Nadia; Anastasia, Luigi; Tettamanti, Guido; Venerando, Bruno

    2012-01-01

    The human plasma membrane sialidase NEU3 is a key enzyme in the catabolism of membrane gangliosides, is crucial in the regulation of cell surface processes, and has been demonstrated to be significantly up-regulated in renal cell carcinomas (RCCs). In this report, we show that NEU3 regulates β1 integrin trafficking in RCC cells by controlling β1 integrin recycling to the plasma membrane and controlling activation of the epidermal growth factor receptor (EGFR) and focal adhesion kinase (FAK)/protein kinase B (AKT) signaling. NEU3 silencing in RCC cells increased the membrane ganglioside content, in particular the GD1a content, and changed the expression of key regulators of the integrin recycling pathway. In addition, NEU3 silencing up-regulated the Ras-related protein RAB25, which directs internalized integrins to lysosomes, and down-regulated the chloride intracellular channel protein 3 (CLIC3), which induces the recycling of internalized integrins to the plasma membrane. In this manner, NEU3 silencing enhanced the caveolar endocytosis of β1 integrin, blocked its recycling and reduced its levels at the plasma membrane, and, consequently, inhibited EGFR and FAK/AKT. These events had the following effects on the behavior of RCC cells: they (a) decreased drug resistance mediated by the block of autophagy and the induction of apoptosis; (b) decreased metastatic potential mediated by down-regulation of the metalloproteinases MMP1 and MMP7; and (c) decreased adhesion to collagen and fibronectin. Therefore, our data identify NEU3 as a key regulator of the β1 integrin-recycling pathway and FAK/AKT signaling and demonstrate its crucial role in RCC malignancy. PMID:23139422

  6. Live Imaging of Cellular Internalization of Single Colloidal Particle by Combined Label-Free and Fluorescence Total Internal Reflection Microscopy.

    Science.gov (United States)

    Byrne, Gerard D; Vllasaliu, Driton; Falcone, Franco H; Somekh, Michael G; Stolnik, Snjezana

    2015-11-02

    In this work we utilize the combination of label-free total internal reflection microscopy and total internal reflectance fluorescence (TIRM/TIRF) microscopy to achieve a simultaneous, live imaging of single, label-free colloidal particle endocytosis by individual cells. The TIRM arm of the microscope enables label free imaging of the colloid and cell membrane features, while the TIRF arm images the dynamics of fluorescent-labeled clathrin (protein involved in endocytosis via clathrin pathway), expressed in transfected 3T3 fibroblasts cells. Using a model polymeric colloid and cells with a fluorescently tagged clathrin endocytosis pathway, we demonstrate that wide field TIRM/TIRF coimaging enables live visualization of the process of colloidal particle interaction with the labeled cell structure, which is valuable for discerning the membrane events and route of colloid internalization by the cell. We further show that 500 nm in diameter model polystyrene colloid associates with clathrin, prior to and during its cellular internalization. This association is not apparent with larger, 1 μm in diameter colloids, indicating an upper particle size limit for clathrin-mediated endocytosis.

  7. Subinternal limiting membrane hemorrhage post-Ahmed glaucoma valve in vitrectomized eye

    Directory of Open Access Journals (Sweden)

    Bhuvan Chanana

    2018-01-01

    Full Text Available Glaucoma drainage devices are mostly used for refractory glaucoma. Early postoperative complications include flat anterior chamber, choroidal effusion, and suprachoroidal hemorrhage. An 8-year-old male patient with a prior history of vitreous surgery for traumatic vitreous hemorrhage, presented to us with angle recession glaucoma in his right eye. His intraocular pressure (IOP was 44 mmHg despite maximum antiglaucoma medication. Ahmed glaucoma valve (AGV surgery was performed to control his IOP. In the early postoperative period, the patient developed premacular subinternal limiting membrane (ILM hemorrhage, which did not resolve even after 4 weeks. Vitreoretinal intervention involving removal of the thickened ILM and sub-ILM bleed had to be performed. To the best of our knowledge, no case has been reported with sub-ILM bleed post aqueous humor shunts. Here, we report a case of premacular sub-ILM bleed following AGV in vitrectomized eye.

  8. Water permeation through anion exchange membranes

    Science.gov (United States)

    Luo, Xiaoyan; Wright, Andrew; Weissbach, Thomas; Holdcroft, Steven

    2018-01-01

    An understanding of water permeation through solid polymer electrolyte (SPE) membranes is crucial to offset the unbalanced water activity within SPE fuel cells. We examine water permeation through an emerging class of anion exchange membranes, hexamethyl-p-terphenyl poly (dimethylbenzimidazolium) (HMT-PMBI), and compare it against series of membrane thickness for a commercial anion exchange membrane (AEM), Fumapem® FAA-3, and a series of proton exchange membranes, Nafion®. The HMT-PMBI membrane is found to possess higher water permeabilities than Fumapem® FAA-3 and comparable permeability than Nafion (H+). By measuring water permeation through membranes of different thicknesses, we are able to decouple, for the first time, internal and interfacial water permeation resistances through anion exchange membranes. Permeation resistances on liquid/membrane interface is found to be negligible compared to that for vapor/membrane for both series of AEMs. Correspondingly, the resistance of liquid water permeation is found to be one order of magnitude smaller compared to that of vapor water permeation. HMT-PMBI possesses larger effective internal water permeation coefficient than both Fumapem® FAA-3 and Nafion® membranes (60 and 18% larger, respectively). In contrast, the effective interfacial permeation coefficient of HMT-PMBI is found to be similar to Fumapem® (±5%) but smaller than Nafion®(H+) (by 14%).

  9. 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.

  10. Design of membrane pressure indicators with strain gages

    International Nuclear Information System (INIS)

    Haberzettl, G.

    1979-01-01

    A special type of pressure indicators, more or less well known under the name of 'membrane pressure indicators' is dealt with. In principle, they consist of a pipe socket which is open at one end and sealed by the 'membrane' at the other end. In case of internal pressure from the open side, the membrane will begin to arch. This arch, which is proportional to the internal pressure, is measured by suitable methods. A special form of strain ganges, so-called 'membrane pressure roses' have turned out to be particularly suitable here. The article gives general guidelines for the construction of membrane pressure indicators. (orig./HT) [de

  11. Tympanic membrane temperature decreases during head up tilt

    DEFF Research Database (Denmark)

    Lorr, David; Lund, Anton; Fredrikson, Mats

    2017-01-01

    INTRODUCTION: Changes in blood flow influence temperature of surrounding tissues. Since the internal carotid artery (ICA) and internal jugular vein (IJV) neighbor the tympanic membrane, changes in their blood flow most likely determine changes in tympanic membrane temperature (TMT). We sought to ...

  12. Registration factors that limit international mobility of people holding physiotherapy qualifications: A systematic review.

    Science.gov (United States)

    Foo, Jonathan S; Storr, Michael; Maloney, Stephen

    2016-06-01

    There is no enforced international standardisation of the physiotherapy profession. Thus, registration is used in many countries to maintain standards of care and to protect the public. However, registration may also limit international workforce mobility. What is known about the professional registration factors that may limit the international mobility of people holding physiotherapy qualifications? Systematic review using an electronic database search and hand searching of the World Confederation for Physical Therapy and International Network of Physiotherapy Regulatory Authorities websites. Analysis was conducted using thematic analysis. 10 articles and eight websites were included from the search strategy. Data is representative of high-income English speaking countries. Four themes emerged regarding limitations to professional mobility: practice context, qualification recognition, verification of fitness to practice, and incidental limitations arising from the registration process. Professional mobility is limited by differences in physiotherapy education programmes, resulting in varying standards of competency. Thus, it is often necessary to verify clinical competencies through assessments, as well as determining professional attributes and ability to apply competencies in a different practice context, as part of the registration process. There has been little evaluation of registration practices, and at present, there is a need to re-evaluate current registration processes to ensure they are efficient and effective, thereby enhancing workforce mobility. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

  13. Solidarity and its limits for economic integration in the EU’s internal market

    DEFF Research Database (Denmark)

    Butler, Graham

    2018-01-01

    Solidarity is applicable to multiple strands of Union law, including in the fostering of an internal market. Whereas the internal market has always held constitutional status, the objects that underlie it came about much later. The question of how solidarity, as a principle, value, and concept...... of the internal market, but also for the purposes of economic integration. The article demonstrates that solidarity in law can be a reason or justification for measures to promote the treaty-based aim of the internal market. Yet simultaneously, it finds that solidarity is not an all-encompassing principle, value......, or concept in absolute terms, and has limits for utilisation in the spirit of European integration. Conclusively, by demonstrating the limits of solidarity as a ‘legal’ principle, value, or concept, the article asks whether it is time to reassess the role that solidarity should play in Union law...

  14. Analysis of proton exchange membrane fuel cell performance with alternate membranes

    Energy Technology Data Exchange (ETDEWEB)

    Wakizoe, Masanobu; Velev, O A; Srinivasan, S [Texas A and M Univ., College Station, TX (United States). Texas Engineering Experiment Station

    1995-02-01

    Renewed interest in proton exchange membrane fuel cell technology for space and terrestrial (particularly electric vehicles) was stimulated by the demonstration, in the mid 1980s, of high energy efficiencies and high power densities. One of the most vital components of the PEMFC is the proton conducting membrane. In this paper, an analysis is made of the performances of PEMFCs with Dupont`s Nafion, Dow`s experimental, and Asahi Chemical`s Aciplex-S membranes. Attempts were also made to draw correlations between the PEMFC performances with the three types of membranes and their physico-chemical characteristics. Practically identical levels of performances (energy efficiency, power density, and lifetime) were achieved in PEMFCs with the Dow and the Aciplex-S membranes and these performances were better than in the PEMFCs with the Nafion-115 membrane. The electrode kinetic parameters for oxygen reduction are better for the PEMFCs with the Aciplex-S and Nafion membranes than with the Dow membranes. The PEMFCs with the Aciplex-S and Dow membranes have nearly the same internal resistances which are considerably lower than for the PEMFC with the Nafion membrane. The desired membrane characteristics to obtain high levels of performance are low equivalent weight and high water content. (Author)

  15. Mesoporous and microporous titania membranes

    NARCIS (Netherlands)

    Sekulic, J.

    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

  16. 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

  17. Glycolipid-Dependent, Protease Sensitive Internalization of Pseudomonas aeruginosa Into Cultured Human Respiratory Epithelial Cells

    Science.gov (United States)

    Emam, Aufaugh; Carter, William G; Lingwood, Clifford

    2010-01-01

    Internalization of PAK strain Pseudomonas aeruginosa into human respiratory epithelial cell lines and HeLa cervical cancer cells in vitro was readily demonstrable via a gentamycin protection assay. Depletion of target cell glycosphingolipids (GSLs) using a glucosyl ceramide synthase inhibitor, P4, completely prevented P. aeruginosa internalization. In contrast, P4 treatment had no effect on the internalization of Salmonella typhimurium into HeLa cells. Internalized P. aeruginosa were within membrane vacuoles, often containing microvesicles, between the bacterium and the limiting membrane. P. aeruginosa internalization was markedly enhanced by target cell pretreatment with the exogenous GSL, deacetyl gangliotetraosyl ceramide (Gg4). Gg4 binds the lipid raft marker, GM1 ganglioside. Target cell pretreatment with TLCK, but not other (serine) protease inhibitors, prevented both P. aeruginosa host cell binding and internalization. NFkB inhibition also prevented internalization. A GSL-containing lipid-raft model of P. aeruginosa host cell binding/internalization is proposed PMID:21270937

  18. Opening the Internal Hematoma Membrane Does Not Alter the Recurrence Rate of Chronic Subdural Hematomas: A Prospective Randomized Trial.

    Science.gov (United States)

    Unterhofer, Claudia; Freyschlag, Christian F; Thomé, Claudius; Ortler, Martin

    2016-08-01

    Factors determining the recurrence of chronic subdural hematomas (CSDHs) are not clear. Whether opening the so-called internal hematoma membrane is useful has not been investigated. To investigate whether splitting the inner hematoma membrane influences the recurrence rate in patients undergoing burr-hole craniotomy for CSDH. Fifty-two awake patients undergoing surgery for 57 CSDHs were prospectively randomized to either partial opening of the inner hematoma membrane (group A) or not (group B) after enlarged burr-hole craniotomy and hematoma evacuation. Drainage was left in situ for several days postoperatively. Groups were comparable with regard to demographic, clinical, and imaging variables. Outcome was assessed after 3-6 weeks for the combined outcome variable of reoperation or residual hematoma of one third or more of the original hematoma thickness. Fourteen patients underwent reoperation for clinical deterioration or residual hematoma during follow-up (n = 6 in group A, 21%; n = 8 in group B, 28 %) (P = 0.537). Residual hematoma of ≥ one third not requiring surgery was present in 7 patients in group A (25%) and 10 patients in group B (36%) (P = 0.383). The overall cumulative failure rate (reoperation or hematoma thickness ≥ one third) was 13/28 (46%) in group A and 18/28 in group B (P = 0.178; relative risk, 0.722 [95% confidence interval, 0.445-1.172]; absolute risk reduction -16% [95% confidence interval, -38% to 8%]). Opening the internal hematoma membrane does not alter the rate of patients requiring revision surgery and the number of patients showing a marked residual hematoma 6 weeks after evacuation of a CSDH. Copyright © 2016 Elsevier Inc. All rights reserved.

  19. Structure and physical properties of bio membranes and model membranes

    International Nuclear Information System (INIS)

    Tibor Hianik

    2006-01-01

    Bio membranes belong to the most important structures of the cell and the cell organelles. They play not only structural role of the barrier separating the external and internal part of the membrane but contain also various functional molecules, like receptors, ionic channels, carriers and enzymes. The cell membrane also preserves non-equilibrium state in a cell which is crucial for maintaining its excitability and other signaling functions. The growing interest to the bio membranes is also due to their unique physical properties. From physical point of view the bio membranes, that are composed of lipid bilayer into which are incorporated integral proteins and on their surface are anchored peripheral proteins and polysaccharides, represent liquid s crystal of smectic type. The bio membranes are characterized by anisotropy of structural and physical properties. The complex structure of bio membranes makes the study of their physical properties rather difficult. Therefore several model systems that mimic the structure of bio membranes were developed. Among them the lipid monolayers at an air-water interphase, bilayer lipid membranes, supported bilayer lipid membranes and liposomes are most known. This work is focused on the introduction into the physical word of the bio membranes and their models. After introduction to the membrane structure and the history of its establishment, the physical properties of the bio membranes and their models are stepwise presented. The most focus is on the properties of lipid monolayers, bilayer lipid membranes, supported bilayer lipid membranes and liposomes that were most detailed studied. This lecture has tutorial character that may be useful for undergraduate and graduate students in the area of biophysics, biochemistry, molecular biology and bioengineering, however it contains also original work of the author and his co-worker and PhD students, that may be useful also for specialists working in the field of bio membranes and model

  20. Cell Membrane Transport Mechanisms: Ion Channels and Electrical Properties of Cell Membranes.

    Science.gov (United States)

    Kulbacka, Julita; Choromańska, Anna; Rossowska, Joanna; Weżgowiec, Joanna; Saczko, Jolanta; Rols, Marie-Pierre

    2017-01-01

    Cellular life strongly depends on the membrane ability to precisely control exchange of solutes between the internal and external (environmental) compartments. This barrier regulates which types of solutes can enter and leave the cell. Transmembrane transport involves complex mechanisms responsible for passive and active carriage of ions and small- and medium-size molecules. Transport mechanisms existing in the biological membranes highly determine proper cellular functions and contribute to drug transport. The present chapter deals with features and electrical properties of the cell membrane and addresses the questions how the cell membrane accomplishes transport functions and how transmembrane transport can be affected. Since dysfunctions of plasma membrane transporters very often are the cause of human diseases, we also report how specific transport mechanisms can be modulated or inhibited in order to enhance the therapeutic effect.

  1. Development of an international BRC [Below Regulatory Concern] limit

    International Nuclear Information System (INIS)

    Kennedy, W.E. Jr.

    1987-07-01

    The International Atomic Energy Agency (IAEA) has recently investigated the exemption from regulatory control of radiation sources containing limited quantities of radioactive materials. Early efforts were entitled de minimis and were aimed at establishing a philosophical basis and radiation dose limits. The main objectives of more recent work on exemption are to illustrate a method for developing practical radiological criteria, to establish generic criteria, and to determine the practicability of the preliminary exemption principles. The method used to develop the criteria relies on models to evaluate the potential radiation exposure pathways and scenarios for individuals and population groups potentially present following the unrestricted release of materials. This paper describes the assessment methods, presents the generic results expressed in terms of the limiting concentrations of selected radionuclides in municipal waste, and provides a comparison with recent regulatory efforts in the United States for considering selected wastes being Below Regulatory Concern (BRC). 17 refs., 4 tabs

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

    Science.gov (United States)

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

    2015-11-01

    Our objectives were to determine the effects of a ceramic microfiltration (MF) membrane's retentate flow channel geometry (round or diamond-shaped) and uniform transmembrane pressure (UTP) on limiting flux (LF) and serum protein (SP) removal during skim milk MF at a temperature of 50°C, a retentate protein concentration of 8.5%, and an average cross-flow velocity of 7 m·s(-1). Performance of membranes with round and diamond flow channels was compared in UTP mode. Performance of the membrane with round flow channels was compared with and without UTP. Using UTP with round flow channel MF membranes increased the LF by 5% when compared with not using UTP, but SP removal was not affected by the use of UTP. Using membranes with round channels instead of diamond-shaped channels in UTP mode increased the LF by 24%. This increase was associated with a 25% increase in Reynolds number and can be explained by lower shear at the vertices of the diamond-shaped channel's surface. The SP removal factor of the diamond channel system was higher than the SP removal factor of the round channel system below the LF. However, the diamond channel system passed more casein into the MF permeate than the round channel system. Because only one batch of each membrane was tested in our study, it was not possible to determine if the differences in protein rejection between channel geometries were due to the membrane design or random manufacturing variation. Despite the lower LF of the diamond channel system, the 47% increase in membrane module surface area of the diamond channel system produced a modular permeate removal rate that was at least 19% higher than the round channel system. Consequently, using diamond channel membranes instead of round channel membranes could reduce some of the costs associated with ceramic MF of skim milk if fewer membrane modules could be used to attain the required membrane area. Copyright © 2015 American Dairy Science Association. Published by Elsevier Inc. All

  3. Membrane Assisted Enzyme Fractionation

    DEFF Research Database (Denmark)

    Yuan, Linfeng

    to the variation in size of the proteins and a reasonable separation factor can be observed only when the size difference is in the order of 10 or more. This is partly caused by concentration polarization and membrane fouling which hinders an effective separation of the proteins. Application of an electric field...... across the porous membrane has been demonstrated to be an effective way to reduce concentration polarization and membrane fouling. In addition, this technique can also be used to separate the proteins based on difference in charge, which to some extent overcome the limitations of size difference...... of proteins on the basis of their charge, degree of hydrophobicity, affinity or size. Adequate purity is often not achieved unless several purification steps are combined thereby increasing cost and reducing product yield. Conventional fractionation of proteins using ultrafiltration membranes is limited...

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

    DEFF Research Database (Denmark)

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

    2013-01-01

    Thin dense membrane layers, mechanically supported by porous substrates, are considered as the most efficient designs for oxygen supply units used in Oxy-fuel processes and membrane reactors. Based on the favorable permeation properties and chemical stability, several materials were suggested...

  5. limit loads for wall-thinning feeder pipes under combined bending and internal pressure

    International Nuclear Information System (INIS)

    Je, Jin Ho; Lee, Kuk Hee; Chung, Ha Joo; Kim, Ju Hee; Han, Jae Jun; Kim, Yun Jae

    2009-01-01

    Flow Accelerated Corrosion (FAC) during inservice conditions produces local wall-thinning in the feeder pipes of CANDU. The Wall-thinning in the feeder pipes is main degradation mechanisms affecting the integrity of piping systems. This paper discusses the integrity assessment of wall-thinned feeder pipes using limit load analysis. Based on finite element limit analyses, this paper compare limit loads for wall-thinning feeder pipes under combined bending and internal pressure with proposed limit loads. The limit loads are determined from limit analyses based on rectangular wall-thinning and elastic-perfectly-plastic materials using the large geometry change.

  6. Proton exchange membrane fuel cell operation and degradation in short-circuit.

    OpenAIRE

    Silva , R.E.; Harel , F.; Jemei , S.; Gouriveau , Rafael; Hissel , Daniel; Boulon , L.; Agbossou , K.

    2013-01-01

    International audience; Hybridization of proton exchange membrane fuel cells (PEMFC) and ultra capacitors (UC) are considered as an alternative way to implement high autonomy, high dynamic, and reversible energy sources. PEMFC allow high efficiency and high autonomy, however their dynamic response is limited and this source does not allow recovering energy. UC appears to be a complementary source to fuel cell systems (FCS) due to their high power density, fast dynamics, and reversibility. A d...

  7. Lipids as organizers of cell membranes.

    Science.gov (United States)

    Kornmann, Benoît; Roux, Aurélien

    2012-08-01

    The 105th Boehringer Ingelheim Fonds International Titisee Conference 'Lipids as Organizers of Cell Membranes' took place in March 2012, in Germany. Kai Simons and Gisou Van der Goot gathered cell biologists and biophysicists to discuss the interplay between lipids and proteins in biological membranes, with an emphasis on how technological advances could help fill the gap in our understanding of the lipid part of the membrane.

  8. Averaging, not internal noise, limits the development of coherent motion processing

    Directory of Open Access Journals (Sweden)

    Catherine Manning

    2014-10-01

    Full Text Available The development of motion processing is a critical part of visual development, allowing children to interact with moving objects and navigate within a dynamic environment. However, global motion processing, which requires pooling motion information across space, develops late, reaching adult-like levels only by mid-to-late childhood. The reasons underlying this protracted development are not yet fully understood. In this study, we sought to determine whether the development of motion coherence sensitivity is limited by internal noise (i.e., imprecision in estimating the directions of individual elements and/or global pooling across local estimates. To this end, we presented equivalent noise direction discrimination tasks and motion coherence tasks at both slow (1.5°/s and fast (6°/s speeds to children aged 5, 7, 9 and 11 years, and adults. We show that, as children get older, their levels of internal noise reduce, and they are able to average across more local motion estimates. Regression analyses indicated, however, that age-related improvements in coherent motion perception are driven solely by improvements in averaging and not by reductions in internal noise. Our results suggest that the development of coherent motion sensitivity is primarily limited by developmental changes within brain regions involved in integrating motion signals (e.g., MT/V5.

  9. Spatiotemporal mapping of diffusion dynamics and organization in plasma membranes

    Science.gov (United States)

    Bag, Nirmalya; Ng, Xue Wen; Sankaran, Jagadish; Wohland, Thorsten

    2016-09-01

    Imaging fluorescence correlation spectroscopy (FCS) and the related FCS diffusion law have been applied in recent years to investigate the diffusion modes of lipids and proteins in membranes. These efforts have provided new insights into the membrane structure below the optical diffraction limit, new information on the existence of lipid domains, and on the influence of the cytoskeleton on membrane dynamics. However, there has been no systematic study to evaluate how domain size, domain density, and the probe partition coefficient affect the resulting imaging FCS diffusion law parameters. Here, we characterize the effects of these factors on the FCS diffusion law through simulations and experiments on lipid bilayers and live cells. By segmenting images into smaller 7  ×  7 pixel areas, we can evaluate the FCS diffusion law on areas smaller than 2 µm and thus provide detailed maps of information on the membrane structure and heterogeneity at this length scale. We support and extend this analysis by deriving a mathematical expression to calculate the mean squared displacement (MSDACF) from the autocorrelation function of imaging FCS, and demonstrate that the MSDACF plots depend on the existence of nanoscopic domains. Based on the results, we derive limits for the detection of domains depending on their size, density, and relative viscosity in comparison to the surroundings. Finally, we apply these measurements to bilayers and live cells using imaging total internal reflection FCS and single plane illumination microscopy FCS.

  10. [Comparison of external fixation with or without limited internal fixation for open knee fractures].

    Science.gov (United States)

    Li, K N; Lan, H; He, Z Y; Wang, X J; Yuan, J; Zhao, P; Mu, J S

    2018-03-01

    Objective: To explore the characteristics and methods of different fixation methods and prevention of open knee joint fracture. Methods: The data of 86 cases of open knee joint fracture admitted from January 2002 to December 2015 in Department of Orthopaedics, Affiliated Hospital of Chengdu University were analyzed retrospectively.There were 65 males and 21 females aged of 38.6 years. There were 38 cases treated with trans articular external fixation alone, 48 cases were in the trans articular external fixation plus auxiliary limited internal fixation group. All the patients were treated according to the same three stages except for different fixation methods. Observation of external fixation and fracture fixation, fracture healing, wound healing and treatment, treatment and related factors of infection control and knee function recovery. χ(2) test was used to analyze data. Results: Eleven patients had primary wound healing, accounting for 12.8%. Seventy-five patients had two wounds healed, accounting for 87.2%. Only 38 cases of trans articular external fixator group had 31 cases of articular surface reduction, accounting for 81.6%; Five cases of trans articular external fixator assisted limited internal fixation group had 5 cases of poor reduction, accounting for 10.4%; There was significant difference between the two groups (χ(2)=44.132, P external fixation group, a total of 23 cases of patients with infection, accounted for 60.5% of external fixation group; trans articular external fixation assisted limited internal fixation group there were 30 cases of patients with infection, accounting for the assistance of external fixator and limited internal fixation group 62.5%; There was significant difference between the two groups(χ(2)=0.035, P >0.05). Five cases of fracture nonunion cases of serious infection, patients voluntarily underwent amputation. The Lysholm Knee Scale: In the external fixation group, 23 cases were less than 50 points, accounting for 60

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

    Science.gov (United States)

    Spiteri Cornish, Kurt; Lois, Noemi; Scott, Neil; Burr, Jennifer; Cook, Jonathan; Boachie, Charles; Tadayoni, Ramin; la Cour, Morten; Christensen, Ulrik; Kwok, Alvin

    2013-06-05

    Several observational studies have suggested the potential benefit of internal limiting membrane (ILM) peeling to treat idiopathic full-thickness macular hole (FTMH). However, no strong evidence is available on the potential benefit(s) of this surgical manoeuvre and uncertainty remains among vitreoretinal surgeons about the indication for peeling the ILM, whether to use it in all cases or in long-standing and/or larger holes.  To determine whether ILM peeling improves anatomical and functional outcomes of macular hole surgery compared with the no-peeling technique and to investigate the impact of different parameters such as presenting vision, stage/size of the hole and duration of symptoms in the success of the surgery. We searched the Cochrane Central Register of Controlled Trials (CENTRAL) which contains the Cochrane Eyes and Vision Group Trials Register (The Cochrane Library 2013, Issue 2), Ovid MEDLINE, Ovid MEDLINE In-Process and Other Non-Indexed Citations, Ovid MEDLINE Daily, Ovid OLDMEDLINE, (January 1950 to February 2013), EMBASE (January 1980 to February 2013), Latin American and Caribbean Literature on Health Sciences (LILACS) (January 1982 to February 2013), the metaRegister of Controlled Trials (mRCT) (www.controlled-trials.com), ClinicalTrials.gov (www.clinicaltrials.gov) and the WHO International Clinical Trials Registry Platform (ICTRP) (www.who.int/ictrp/search/en). We searched the reference lists of included studies for any additional studies not identified by the electronic searches. We did not use any date or language restrictions in the electronic searches for trials. We last searched the electronic databases on 28 February 2013.We searched reference lists of the studies included in the review for information about other studies on ILM peeling in macular hole surgery. We searched Proceedings for the following conferences up to February 2013: American Academy of Ophthalmology (AAO), Annual Meeting of the American Society of Retina Specialists

  12. Variable-angle total internal reflection fluorescence microscopy of intact cells of Arabidopsis thaliana

    Directory of Open Access Journals (Sweden)

    Kim Myung K

    2011-09-01

    Full Text Available Abstract Background Total internal reflection fluorescence microscopy (TIRFM is a powerful tool for observing fluorescently labeled molecules on the plasma membrane surface of animal cells. However, the utility of TIRFM in plant cell studies has been limited by the fact that plants have cell walls, thick peripheral layers surrounding the plasma membrane. Recently, a new technique known as variable-angle epifluorescence microscopy (VAEM was developed to circumvent this problem. However, the lack of a detailed analysis of the optical principles underlying VAEM has limited its applications in plant-cell biology. Results Here, we present theoretical and experimental evidence supporting the use of variable-angle TIRFM in observations of intact plant cells. We show that when total internal reflection occurs at the cell wall/cytosol interface with an appropriate angle of incidence, an evanescent wave field of constant depth is produced inside the cytosol. Results of experimental TIRFM observations of the dynamic behaviors of phototropin 1 (a membrane receptor protein and clathrin light chain (a vesicle coat protein support our theoretical analysis. Conclusions These findings demonstrate that variable-angle TIRFM is appropriate for quantitative live imaging of cells in intact tissues of Arabidopsis thaliana.

  13. Internal hydration H{sub 2}/O{sub 2} 100 cm{sup 2} polymer electrolyte membrane fuel cell

    Energy Technology Data Exchange (ETDEWEB)

    Miachon, S [CEA, Dept. de Recherche Fondamentale sur la Matiere Condensee, SESAM/PCM, 38 - Grenoble (France); Aldebert, P [CEA, Dept. de Recherche Fondamentale sur la Matiere Condensee, SESAM/PCM, 38 - Grenoble (France)

    1995-07-01

    This work deals with a new arrangement of a polymer electrolyte membrane fuel cell (PEMFC) support which allows the operation of a 100 cm{sup 2} surface area fuel cell with cold and unhumidified gases. Hydrogen is not recycled. Both gases (pure hydrogen and oxygen) are heated and humidified internally, each one crossing a porous carbon block. This allows a simplified water management. Classical low platinum loading E-Tek{sup R} electrodes, hot-pressed on Nafion{sup R} 117 and 112 membranes, are used. Performances are then a little higher than those of comparable PEMFCs in the literature: 0.7 V at 0.7 A/cm{sup 2} for Nafion{sup R} 117, and 0.724 V at 1 A/cm{sup 2} for Nafion{sup R} 112, under 4/6 bar (absolute) of H{sub 2}/O{sub 2} at 100 C. The values of PEMFC resistance obtained in fitting the data were found to be R=0.254 (with Nafion{sup R} 117) and 0.108 {Omega} cm{sup 2} (with Nafion{sup R} 112). The membrane contribution to the cell resistance was then estimated to be R{sub m}=0.204 and 0.058 {Omega} cm{sup 2}, respectively (with Nafion{sup R} conductivity estimated at 0.103 S/cm at 100 C in working fuel cell conditions). This membrane is therefore the major contributor to the total cell resistance. (orig.)

  14. Endocytosis of GPI-linked membrane folate receptor-alpha.

    Science.gov (United States)

    Rijnboutt, S; Jansen, G; Posthuma, G; Hynes, J B; Schornagel, J H; Strous, G J

    1996-01-01

    GPI-linked membrane folate receptors (MFRs) have been implicated in the receptor-mediated uptake of reduced folate cofactors and folate-based chemotherapeutic drugs. We have studied the biosynthetic transport to and internalization of MFR isoform alpha in KB-cells. MFR-alpha was synthesized as a 32-kD protein and converted in a maturely glycosylated 36-38-kD protein 1 h after synthesis. 32-kD MFR-alpha was completely soluble in Triton X-100 at 0 degree C. In contrast, only 33% of the 36-38-kD species could be solubilized at these conditions whereas complete solubilization was obtained in Triton X-100 at 37 degrees C or in the presence of saponin at 0 degree C. Similar solubilization characteristics were found when MFR-alpha at the plasma membrane was labeled with a crosslinkable 125I-labeled photoaffinity-analog of folic acid as a ligand. Triton X-100-insoluble membrane domains containing MFR-alpha could be separated from soluble MFR-alpha on sucrose flotation gradients. Only Triton X-100 soluble MFR-alpha was internalized from the plasma membrane. The reduced-folate-carrier, an integral membrane protein capable of translocating (anti-)folates across membranes, was completely excluded from the Triton X-100-resistant membrane domains. Internalized MFR-alpha recycled slowly to the cell surface during which it remained soluble in Triton X-100 at 0 degree C. Using immunoelectron microscopy, we found MFR-alpha along the entire endocytic pathway: in clathrin-coated buds and vesicles, and in small and large endosomal vacuoles. In conclusion, our data indicate that a large fraction, if not all, of internalizing MFR-alpha bypasses caveolae.

  15. Analysis of protein interactions at native chloroplast membranes by ellipsometry.

    Directory of Open Access Journals (Sweden)

    Verena Kriechbaumer

    Full Text Available Membrane bound receptors play vital roles in cell signaling, and are the target for many drugs, yet their interactions with ligands are difficult to study by conventional techniques due to the technical difficulty of monitoring these interactions in lipid environments. In particular, the ability to analyse the behaviour of membrane proteins in their native membrane environment is limited. Here, we have developed a quantitative approach to detect specific interactions between low-abundance chaperone receptors within native chloroplast membranes and their soluble chaperone partners. Langmuir-Schaefer film deposition was used to deposit native chloroplasts onto gold-coated glass slides, and interactions between the molecular chaperones Hsp70 and Hsp90 and their receptors in the chloroplast membranes were detected and quantified by total internal reflection ellipsometry (TIRE. We show that native chloroplast membranes deposited on gold-coated glass slides using Langmuir-Schaefer films retain functional receptors capable of binding chaperones with high specificity and affinity. Taking into account the low chaperone receptor abundance in native membranes, these binding properties are consistent with data generated using soluble forms of the chloroplast chaperone receptors, OEP61 and Toc64. Therefore, we conclude that chloroplasts have the capacity to selectively bind chaperones, consistent with the notion that chaperones play an important role in protein targeting to chloroplasts. Importantly, this method of monitoring by TIRE does not require any protein labelling. This novel combination of techniques should be applicable to a wide variety of membranes and membrane protein receptors, thus presenting the opportunity to quantify protein interactions involved in fundamental cellular processes, and to screen for drugs that target membrane proteins.

  16. INTERNAL LIMITING MEMBRANE PEELING VERSUS INVERTED FLAP TECHNIQUE FOR TREATMENT OF FULL-THICKNESS MACULAR HOLES: A COMPARATIVE STUDY IN A LARGE SERIES OF PATIENTS.

    Science.gov (United States)

    Rizzo, Stanislao; Tartaro, Ruggero; Barca, Francesco; Caporossi, Tomaso; Bacherini, Daniela; Giansanti, Fabrizio

    2017-12-08

    The inverted flap (IF) technique has recently been introduced in macular hole (MH) surgery. The IF technique has shown an increase of the success rate in the case of large MHs and in MHs associated with high myopia. This study reports the anatomical and functional results in a large series of patients affected by MH treated using pars plana vitrectomy and gas tamponade combined with internal limiting membrane (ILM) peeling or IF. This is a retrospective, consecutive, nonrandomized comparative study of patients affected by idiopathic or myopic MH treated using small-gauge pars plana vitrectomy (25- or 23-gauge) between January 2011 and May 2016. The patients were divided into two groups according to the ILM removal technique (complete removal vs. IF). A subgroup analysis was performed according to the MH diameter (MH peeling and 320 patients underwent pars plana vitrectomy and IF. Overall, 84.94% of the patients had complete anatomical success characterized by MH closure after the operation. In particular, among the patients who underwent only ILM peeling the closure rate was 78.75%; among the patients who underwent the IF technique, it was 91.93% (P = 0.001); and among the patients affected by full-thickness MH ≥400 µm, success was achieved in 95.6% of the cases in the IF group and in 78.6% in the ILM peeling group (P = 0.001); among the patients with an axial length ≥26 mm, success was achieved in 88.4% of the cases in the IF group and in 38.9% in the ILM peeling group (P = 0.001). Average preoperative best-corrected visual acuity was 0.77 (SD = 0.32) logarithm of the minimum angle of resolution (20/118 Snellen) in the peeling group and 0.74 (SD = 0.33) logarithm of the minimum angle of resolution (20/110 Snellen) in the IF group (P = 0.31). Mean postoperative best-corrected visual acuity was 0.52 (SD = 0.42) logarithm of the minimum angle of resolution (20/66 Snellen) in the peeling group and 0.43 (SD = 0.31) logarithm of the minimum angle of resolution (20

  17. Mechanics of Lipid Bilayer Membranes

    Science.gov (United States)

    Powers, Thomas R.

    All cells have membranes. The plasma membrane encapsulates the cell's interior, acting as a barrier against the outside world. In cells with nuclei (eukaryotic cells), membranes also form internal compartments (organelles) which carry out specialized tasks, such as protein modification and sorting in the case of the Golgi apparatus, and ATP production in the case of mitochondria. The main components of membranes are lipids and proteins. The proteins can be channels, carriers, receptors, catalysts, signaling molecules, or structural elements, and typically contribute a substantial fraction of the total membrane dry weight. The equilibrium properties of pure lipid membranes are relatively well-understood, and will be the main focus of this article. The framework of elasticity theory and statistical mechanics that we will develop will serve as the foundation for understanding biological phenomena such as the nonequilibrium behavior of membranes laden with ion pumps, the role of membrane elasticity in ion channel gating, and the dynamics of vesicle fission and fusion. Understanding the mechanics of lipid membranes is also important for drug encapsulation and delivery.

  18. Functional role of the extracellular N-terminal domain of neuropeptide Y subfamily receptors in membrane integration and agonist-stimulated internalization.

    Science.gov (United States)

    Lindner, Diana; Walther, Cornelia; Tennemann, Anja; Beck-Sickinger, Annette G

    2009-01-01

    The N terminus is the most variable element in G protein-coupled receptors (GPCRs), ranging from seven residues up to approximately 5900 residues. For family B and C GPCRs it is described that at least part of the ligand binding site is located within the N terminus. Here we investigated the role of the N terminus in the neuropeptide Y receptor family, which belongs to the class A of GPCRs. We cloned differentially truncated Y receptor mutants, in which the N terminus was partially or completely deleted. We found, that eight amino acids are sufficient for full ligand binding and signal transduction activity. Interestingly, we could show that no specific amino acids but rather the extension of the first transmembrane helix by any residues is sufficient for receptor activity but also for membrane integration in case of the hY(1) and the hY(4) receptors. In contrast, the complete deletion of the N terminus in the hY(2) receptors resulted in a mutant that is fully integrated in the membrane but does not bind the ligand very well and internalizes much slower compared to the wild type receptor. Interestingly, also these effects could be reverted by any N-terminal extension. Accordingly, the most important function of the N termini seems to be the stabilization of the first transmembrane helix to ensure the correct receptor structure, which obviously is essential for ligand binding, integration into the cell membrane and receptor internalization.

  19. Rapid evaporation at the superheat limit of methanol, ethanol, butanol and n-heptane on platinum films supported by low-stress SiN membranes.

    Science.gov (United States)

    Ching, Eric J; Avedisian, C Thomas; Cavicchi, Richard C; Chung, Do Hyun; Rah, Jeff; Carrier, Michael J

    2016-10-01

    The bubble nucleation temperatures of several organic liquids (methanol, ethanol, butanol, n-heptane) on stress-minimized platinum (Pt) films supported by SiN membranes is examined by pulse-heating the membranes for times ranging from 1 µs to 10 µs. The results show that the nucleation temperatures increase as the heating rates of the Pt films increase. Measured nucleation temperatures approach predicted superheat limits for the smallest pulse times which correspond to heating rates over 10 8 K/s, while nucleation temperatures are significantly lower for the longest pulse times. The microheater membranes were found to be robust for millions of pulse cycles, which suggests their potential in applications for moving fluids on the microscale and for more fundamental studies of phase transitions of metastable liquids.

  20. A study of the internal humidification of an integrated PEMFC stack

    Energy Technology Data Exchange (ETDEWEB)

    Choi, K H; Lee, T H [Yonsei Univ., Seoul (Korea, Republic of). Dept. of Chemical Engineering; Park, D J; Rho, Y W; Kho, Y T [KOGAS R and D Center, Kyunggi (Korea, Republic of)

    1998-07-15

    An integrated proton exchange membrane fuel-cell (PFMFC) system has been developed with an internal humidifier within the stack. Research is concentrated on selecting a membrane with low cost and good water permeability because, to date, high-cost membranes (e.g., as Nafion) have been used. The gas and water permeability of several membranes were measured. A low-cost ultra filtration (UF) membrane shows better characteristics for the internal humidifier and cell performance than the others. Also, saturated water vapour permeating through the UF membrane can be supplied at the stack from the internal humidifier. The internal humidifier using UF membrane is thought to be a satisfactory humidifier for a PEMPC. (orig.)

  1. Membrane modules for building ventilation

    Energy Technology Data Exchange (ETDEWEB)

    Kistler, K.R.; Cussler, E.L.

    2002-01-01

    Hollow fibre and flat sheet membranes with an interfacially polymerized coating of polyamide have a permeance for water vapour of about 0.16 m sec{sup -1}. These membranes can serve as a basis for building ventilation which provides fresh air while recovering about 70% of the specific heat and 60% of the latent heat. Because these membranes are selective for water vapour, the air is exhausted with internal pollutants like carbon monoxide, formaldehyde, and radon. The expense of the ventilator should be recovered in reduced heating costs in about three years. (Author)

  2. 14 CFR 399.41 - Zones of limited suspension for international cargo rates.

    Science.gov (United States)

    2010-01-01

    ... TRANSPORTATION (AVIATION PROCEEDINGS) POLICY STATEMENTS STATEMENTS OF GENERAL POLICY Policies Relating to Rates and Tariffs § 399.41 Zones of limited suspension for international cargo rates. (a) Applicability. This section states the Board's policy for suspending rate changes for the transportation of property...

  3. The Method of Economic Analysis of International Law: What are its Limits?

    DEFF Research Database (Denmark)

    Tang, Yi Shin

    2016-01-01

    in specific contemporary issues such as international security, trade and environment. The article also points out the most important limitations of this approach, which mainly derive from a misunderstanding of the assumptions behind the use of rational choice theories, particularly through a recurrent...

  4. 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...

  5. Ion Transport through Diffusion Layer Controlled by Charge Mosaic Membrane

    Directory of Open Access Journals (Sweden)

    Akira Yamauchi

    2012-01-01

    Full Text Available The kinetic transport behaviors in near interface of the membranes were studied using commercial anion and cation exchange membrane and charge mosaic membrane. Current-voltage curve gave the limiting current density that indicates the ceiling of conventional flux. From chronopotentiometry above the limiting current density, the transition time was estimated. The thickness of boundary layer was derived with conjunction with the conventional limiting current density and the transition time from steady state flux. On the other hand, the charge mosaic membrane was introduced in order to examine the ion transport on the membrane surface in detail. The concentration profile was discussed by the kinetic transport number with regard to the water dissociation (splitting on the membrane surface.

  6. Proteomics and the dynamic plasma membrane

    DEFF Research Database (Denmark)

    Sprenger, Richard R; Jensen, Ole Nørregaard

    2010-01-01

    plasma membrane is of particular interest, by not only serving as a barrier between the "cell interior" and the external environment, but moreover by organizing and clustering essential components to enable dynamic responses to internal and external stimuli. Defining and characterizing the dynamic plasma...... the challenges in functional proteomic studies of the plasma membrane. We review the recent progress in MS-based plasma membrane proteomics by presenting key examples from eukaryotic systems, including mammals, yeast and plants. We highlight the importance of enrichment and quantification technologies required...... for detailed functional and comparative analysis of the dynamic plasma membrane proteome....

  7. Durability of PEM Fuel Cell Membranes

    Science.gov (United States)

    Huang, Xinyu; Reifsnider, Ken

    Durability is still a critical limiting factor for the commercialization of polymer electrolyte membrane (PEM) fuel cells, a leading energy conversion technology for powering future hydrogen fueled automobiles, backup power systems (e.g., for base transceiver station of cellular networks), portable electronic devices, etc. Ionic conducting polymer (ionomer) electrolyte membranes are the critical enabling materials for the PEM fuel cells. They are also widely used as the central functional elements in hydrogen generation (e.g., electrolyzers), membrane cell for chlor-alkali production, etc. A perfluorosulfonic acid (PFSA) polymer with the trade name Nafion® developed by DuPont™ is the most widely used PEM in chlor-alkali cells and PEM fuel cells. Similar PFSA membranes have been developed by Dow Chemical, Asahi Glass, and lately Solvay Solexis. Frequently, such membranes serve the dual function of reactant separation and selective ionic conduction between two otherwise separate compartments. For some applications, the compromise of the "separation" function via the degradation and mechanical failure of the electrolyte membrane can be the life-limiting factor; this is particularly the case for PEM in hydrogen/oxygen fuel cells.

  8. Mapping the Local Organization of Cell Membranes Using Excitation-Polarization-Resolved Confocal Fluorescence Microscopy

    OpenAIRE

    Kress, Alla; Wang, Xiao; Ranchon, Hubert; Savatier, Julien; Rigneault, Hervé; Ferrand, Patrick; Brasselet, Sophie

    2013-01-01

    International audience; Fluorescence anisotropy and linear dichroism imaging have been widely used for imaging biomolecular orientational distributions in protein aggregates, fibrillar structures of cells, and cell membranes. However, these techniques do not give access to complete orientational order information in a whole image, because their use is limited to parts of the sample where the average orientation of molecules is known a priori. Fluorescence anisotropy is also highly sensitive t...

  9. Anatomical influences on internally coupled ears in reptiles.

    Science.gov (United States)

    Young, Bruce A

    2016-10-01

    Many reptiles, and other vertebrates, have internally coupled ears in which a patent anatomical connection allows pressure waves generated by the displacement of one tympanic membrane to propagate (internally) through the head and, ultimately, influence the displacement of the contralateral tympanic membrane. The pattern of tympanic displacement caused by this internal coupling can give rise to novel sensory cues. The auditory mechanics of reptiles exhibit more anatomical variation than in any other vertebrate group. This variation includes structural features such as diverticula and septa, as well as coverings of the tympanic membrane. Many of these anatomical features would likely influence the functional significance of the internal coupling between the tympanic membranes. Several of the anatomical components of the reptilian internally coupled ear are under active motor control, suggesting that in some reptiles the auditory system may be more dynamic than previously recognized.

  10. Quantitative measurement of cell membrane receptor internalization by the nanoluciferase reporter: Using the G protein-coupled receptor RXFP3 as a model.

    Science.gov (United States)

    Liu, Yu; Song, Ge; Shao, Xiao-Xia; Liu, Ya-Li; Guo, Zhan-Yun

    2015-02-01

    Nanoluciferase (NanoLuc) is a newly developed small luciferase reporter with the brightest bioluminescence to date. In the present work, we developed NanoLuc as a sensitive bioluminescent reporter to measure quantitatively the internalization of cell membrane receptors, based on the pH dependence of the reporter activity. The G protein-coupled receptor RXFP3, the cognate receptor of relaxin-3/INSL7, was used as a model receptor. We first generated stable HEK293T cells that inducibly coexpressed a C-terminally NanoLuc-tagged human RXFP3 and a C-terminally enhanced green fluorescent protein (EGFP)-tagged human RXFP3. The C-terminal EGFP-tag and NanoLuc-tag had no detrimental effects on the ligand-binding potency and intracellular trafficking of RXFP3. Based on the fluorescence of the tagged EGFP reporter, the ligand-induced RXFP3 internalization was visualized directly under a fluorescence microscope. Based on the bioluminescence of the tagged NanoLuc reporter, the ligand-induced RXFP3 internalization was measured quantitatively by a convenient bioluminescent assay. Coexpression of an EGFP-tagged inactive [E141R]RXFP3 had no detrimental effect on the ligand-binding potency and ligand-induced internalization of the NanoLuc-tagged wild-type RXFP3, suggesting that the mutant RXFP3 and wild-type RXFP3 worked independently. The present bioluminescent internalization assay could be extended to other G protein-coupled receptors and other cell membrane receptors to study ligand-receptor and receptor-receptor interactions. Copyright © 2014 Elsevier B.V. All rights reserved.

  11. Protein kinase A-induced internalization of Slack channels from the neuronal membrane occurs by adaptor protein-2/clathrin-mediated endocytosis.

    Science.gov (United States)

    Gururaj, Sushmitha; Evely, Katherine M; Pryce, Kerri D; Li, Jun; Qu, Jun; Bhattacharjee, Arin

    2017-11-24

    The sodium-activated potassium (K Na ) channel Kcnt1 (Slack) is abundantly expressed in nociceptor (pain-sensing) neurons of the dorsal root ganglion (DRG), where they transmit the large outward conductance I KNa and arbitrate membrane excitability. Slack channel expression at the DRG membrane is necessary for their characteristic firing accommodation during maintained stimulation, and reduced membrane channel density causes hyperexcitability. We have previously shown that in a pro-inflammatory state, a decrease in membrane channel expression leading to reduced Slack-mediated I KNa expression underlies DRG neuronal sensitization. An important component of the inflammatory milieu, PKA internalizes Slack channels from the DRG membrane, reduces I KNa , and produces DRG neuronal hyperexcitability when activated in cultured primary DRG neurons. Here, we show that this PKA-induced retrograde trafficking of Slack channels also occurs in intact spinal cord slices and that it is carried out by adaptor protein-2 (AP-2) via clathrin-mediated endocytosis. We provide mass spectrometric and biochemical evidence of an association of native neuronal AP-2 adaptor proteins with Slack channels, facilitated by a dileucine motif housed in the cytoplasmic Slack C terminus that binds AP-2. By creating a competitive peptide blocker of AP-2-Slack binding, we demonstrated that this interaction is essential for clathrin recruitment to the DRG membrane, Slack channel endocytosis, and DRG neuronal hyperexcitability after PKA activation. Together, these findings uncover AP-2 and clathrin as players in Slack channel regulation. Given the significant role of Slack in nociceptive neuronal excitability, the AP-2 clathrin-mediated endocytosis trafficking mechanism may enable targeting of peripheral and possibly, central neuronal sensitization. © 2017 by The American Society for Biochemistry and Molecular Biology, Inc.

  12. Fouling in a MBR system with rotating membrane discs

    DEFF Research Database (Denmark)

    Jørgensen, Mads Koustrup; Bentzen, Thomas Ruby; Christensen, Morten Lykkegaard

    concentrations and a clear effluent with no bacteria present in the permeate [1]. However, the process performance is limited by membrane fouling, which results in a lower productivity and higher energy demand and hence places demands for limitation of fouling and/or cleaning of the membranes. One way to do...... uses rotating ceramic membrane discs for creation of shear, which can be changed by controlling the membrane rotation speed of the membrane. Furthermore, the influence of shear on fouling is studied at different radii from the center of rotation, by dividing membranes into different concentric rings......Membrane bioreactors (MBR) are an attractive alternative solution for municipal and industrial wastewater treatment. The MBR, which is a combination of a bioreactor for sludge degradation and a membrane for separation, has the advantages of a low footprint, ability to handle high sludge...

  13. Glucose oxidase as a biocatalytic enzyme-based bio-fuel cell using Nafion membrane limiting crossover

    International Nuclear Information System (INIS)

    Naidoo, S; Blottnitz, H; Naidoo, Q; Vaivars, G

    2013-01-01

    A novel combination for an Enzyme-based Biofuel cell included a Nafion membrane as an ion transporter that maintained a working cell charge and inhibited membrane degradation. The prototype cell chamber used oxygen (O 2 ) in the cathode cell and glucose in the anode. The Nafion membrane stability studied here was evidently in the region of 0% loss of conductivity as the charge was constant and increased after the addition of glucose. The prototype cell chamber used NaCl in the cathode cell and glucose oxidase (GOx) in the anodic chamber was successfully studied for membrane stability showed in this study no evidence of poisoning from membrane leakage in a controlled pH environment. There was no crossover at the anaerobic operating ambient temperatures and under physiological pH 5 – 7 conditions. In this research we have successfully used a Nafion membrane together with GOx and under controlled conditions produced respectable power densities

  14. Mechanism of membranous tunnelling nanotube formation in viral genome delivery.

    Directory of Open Access Journals (Sweden)

    Bibiana Peralta

    2013-09-01

    Full Text Available In internal membrane-containing viruses, a lipid vesicle enclosed by the icosahedral capsid protects the genome. It has been postulated that this internal membrane is the genome delivery device of the virus. Viruses built with this architectural principle infect hosts in all three domains of cellular life. Here, using a combination of electron microscopy techniques, we investigate bacteriophage PRD1, the best understood model for such viruses, to unveil the mechanism behind the genome translocation across the cell envelope. To deliver its double-stranded DNA, the icosahedral protein-rich virus membrane transforms into a tubular structure protruding from one of the 12 vertices of the capsid. We suggest that this viral nanotube exits from the same vertex used for DNA packaging, which is biochemically distinct from the other 11. The tube crosses the capsid through an aperture corresponding to the loss of the peripentonal P3 major capsid protein trimers, penton protein P31 and membrane protein P16. The remodeling of the internal viral membrane is nucleated by changes in osmolarity and loss of capsid-membrane interactions as consequence of the de-capping of the vertices. This engages the polymerization of the tail tube, which is structured by membrane-associated proteins. We have observed that the proteo-lipidic tube in vivo can pierce the gram-negative bacterial cell envelope allowing the viral genome to be shuttled to the host cell. The internal diameter of the tube allows one double-stranded DNA chain to be translocated. We conclude that the assembly principles of the viral tunneling nanotube take advantage of proteo-lipid interactions that confer to the tail tube elastic, mechanical and functional properties employed also in other protein-membrane systems.

  15. Pilot demonstration of energy-efficient membrane bioreactor (MBR) using reciprocating submerged membrane.

    Science.gov (United States)

    Ho, Jaeho; Smith, Shaleena; Patamasank, Jaren; Tontcheva, Petia; Kim, Gyu Dong; Roh, Hyung Keun

    2015-03-01

    Membrane bioreactor (MBR) is becoming popular for advanced wastewater treatment and water reuse. Air scouring to "shake" the membrane fibers is most suitable and applicable to maintain filtration without severe and rapidfouling. However, membrane fouling mitigating technologies are energy intensive. The goal of this research is to develop an alternative energy-saving MBR system to reduce energy consumption; a revolutionary system that will directly compete with air scouring technologies currently in the membrane water reuse market. The innovative MBR system, called reciprocation MBR (rMBR), prevents membrane fouling without the use of air scouring blowers. The mechanism featured is a mechanical reciprocating membrane frame that uses inertia to prevent fouling. Direct strong agitation of the fiber is also beneficial for the constant removal of solids built up on the membrane surface. The rMBR pilot consumes less energy than conventional coarse air scouring MBR systems. Specific energy consumption for membrane reciprocation for the pilot rMBR system was 0.072 kWh/m3 permeate produced at 40 LMH, which is 75% less than the conventional air scouring in an MBR system (0.29 kWh/m3). Reciprocation of the hollow-fiber membrane can overcome the hydrodynamic limitations of air scouring or cross-flow membrane systems with less energy consumption and/or higher energy efficiency.

  16. β-arrestin regulates estradiol membrane-initiated signaling in hypothalamic neurons.

    Directory of Open Access Journals (Sweden)

    Angela M Wong

    Full Text Available Estradiol (E2 action in the nervous system is the result of both direct nuclear and membrane-initiated signaling (EMS. E2 regulates membrane estrogen receptor-α (ERα levels through opposing mechanisms of EMS-mediated trafficking and internalization. While ß-arrestin-mediated mERα internalization has been described in the cortex, a role of ß-arrestin in EMS, which underlies multiple physiological processes, remains undefined. In the arcuate nucleus of the hypothalamus (ARH, membrane-initiated E2 signaling modulates lordosis behavior, a measure of female sexually receptivity. To better understand EMS and regulation of ERα membrane levels, we examined the role of ß-arrestin, a molecule associated with internalization following agonist stimulation. In the present study, we used an immortalized neuronal cell line derived from embryonic hypothalamic neurons, the N-38 line, to examine whether ß-arrestins mediate internalization of mERα. β-arrestin-1 (Arrb1 was found in the ARH and in N-38 neurons. In vitro, E2 increased trafficking and internalization of full-length ERα and ERαΔ4, an alternatively spliced isoform of ERα, which predominates in the membrane. Treatment with E2 also increased phosphorylation of extracellular-signal regulated kinases 1/2 (ERK1/2 in N-38 neurons. Arrb1 siRNA knockdown prevented E2-induced ERαΔ4 internalization and ERK1/2 phosphorylation. In vivo, microinfusions of Arrb1 antisense oligodeoxynucleotides (ODN into female rat ARH knocked down Arrb1 and prevented estradiol benzoate-induced lordosis behavior compared with nonsense scrambled ODN (lordosis quotient: 3 ± 2.1 vs. 85.0 ± 6.0; p < 0.0001. These results indicate a role for Arrb1 in both EMS and internalization of mERα, which are required for the E2-induction of female sexual receptivity.

  17. Scaling and particulate fouling in membrane filtration systems

    NARCIS (Netherlands)

    Boerlage, S.F.E.

    2001-01-01

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

  18. Integrable structure in discrete shell membrane theory.

    Science.gov (United States)

    Schief, W K

    2014-05-08

    We present natural discrete analogues of two integrable classes of shell membranes. By construction, these discrete shell membranes are in equilibrium with respect to suitably chosen internal stresses and external forces. The integrability of the underlying equilibrium equations is proved by relating the geometry of the discrete shell membranes to discrete O surface theory. We establish connections with generalized barycentric coordinates and nine-point centres and identify a discrete version of the classical Gauss equation of surface theory.

  19. Integrin-based diffusion barrier separates membrane domains enabling the formation of microbiostatic frustrated phagosomes

    Science.gov (United States)

    Maxson, Michelle E; Naj, Xenia; O'Meara, Teresa R; Plumb, Jonathan D; Cowen, Leah E

    2018-01-01

    Candida albicans hyphae can reach enormous lengths, precluding their internalization by phagocytes. Nevertheless, macrophages engulf a portion of the hypha, generating incompletely sealed tubular phagosomes. These frustrated phagosomes are stabilized by a thick cuff of F-actin that polymerizes in response to non-canonical activation of integrins by fungal glycan. Despite their continuity, the surface and invaginating phagosomal membranes retain a strikingly distinct lipid composition. PtdIns(4,5)P2 is present at the plasmalemma but is not detectable in the phagosomal membrane, while PtdIns(3)P and PtdIns(3,4,5)P3 co-exist in the phagosomes yet are absent from the surface membrane. Moreover, endo-lysosomal proteins are present only in the phagosomal membrane. Fluorescence recovery after photobleaching revealed the presence of a diffusion barrier that maintains the identity of the open tubular phagosome separate from the plasmalemma. Formation of this barrier depends on Syk, Pyk2/Fak and formin-dependent actin assembly. Antimicrobial mechanisms can thereby be deployed, limiting the growth of the hyphae. PMID:29553370

  20. Potentiometric measurement of polymer-membrane electrodes based on lanthanum

    Energy Technology Data Exchange (ETDEWEB)

    Saefurohman, Asep, E-mail: saefurohman.asep78@Gmail.com; Buchari,, E-mail: saefurohman.asep78@Gmail.com; Noviandri, Indra, E-mail: saefurohman.asep78@Gmail.com [Department of Chemistry, Bandung Institute of Technology (Indonesia); Syoni [Department of Metallurgy Engineering, Bandung Institute of Technology (Indonesia)

    2014-03-24

    Quantitative analysis of rare earth elements which are considered as the standard method that has a high accuracy, and detection limits achieved by the order of ppm is inductively coupled plasma atomic emission spectroscopy (ICPAES). But these tools are expensive and valuable analysis of the high cost of implementation. In this study be made and characterized selective electrode for the determination of rare earth ions is potentiometric. Membrane manufacturing techniques studied is based on immersion (liquid impregnated membrane) in PTFE 0.5 pore size. As ionophores to be used tri butyl phosphate (TBP) and bis(2-etylhexyl) hydrogen phosphate. There is no report previously that TBP used as ionophore in polymeric membrane based lanthanum. Some parameters that affect the performance of membrane electrode such as membrane composition, membrane thickness, and types of membrane materials studied in this research. Manufacturing of Ion Selective Electrodes (ISE) Lanthanum (La) by means of impregnation La membrane in TBP in kerosene solution has been done and showed performance for ISE-La. FTIR spectrum results for PTFE 0.5 pore size which impregnated in TBP and PTFE blank showed difference of spectra in the top 1257 cm{sup −1}, 1031 cm{sup −1} and 794.7 cm{sup −1} for P=O stretching and stretching POC from group −OP =O. The result showed shift wave number for P =O stretching of the cluster (−OP=O) in PTFE-TBP mixture that is at the peak of 1230 cm{sup −1} indicated that no interaction bond between hydroxyl group of molecules with molecular clusters fosforil of TBP or R{sub 3}P = O. The membrane had stable responses in pH range between 1 and 9. Good responses were obtained using 10{sup −3} M La(III) internal solution, which produced relatively high potential. ISE-La showed relatively good performances. The electrode had a response time of 29±4.5 second and could be use for 50 days. The linear range was between 10{sup −5} and 10{sup −1} M.

  1. [Treatment of pediatric distal femur fractures by external fixator combined with limited internal fixation].

    Science.gov (United States)

    Wei, Sheng-wang; Shi, Zhan-ying; Hu, Ju-zheng; Wu, Hao

    2016-03-01

    To discuss the clinical effects of external fixator combined with limited internal fixation in the treatment of pediatric distal femur fractures. From January 2008 to June 2014, 17 children of distal femur fractures were treated by external fixator combined with limited internal fixation. There were 12 males and 5 females, aged from 6 to 13 years old with an average of 10.2 years, ranged in the course of disease from 1 h to 2 d. Preoperative diagnoses were confirmed by X-ray films in all children. There were 11 patients with supracondylar fracture , and 6 patients with intercondylar comminuted fracture. According to AO/ASIF classification, 9 fractures were type A1, 5 cases were type A2,and 3 cases were type C1. The intraoperative and postoperative complications, postoperative radiological examination, lower limbs length and motion of knee joints were observed. Knee joint function was assessed by KSS score. All the patients were followed up from 6 to 38 months with an average of 24.4 months. No nerve or blood vessel injury was found. One case complicated with the external fixation loosening, 2 cases with the infection of pin hole and 3 cases with the leg length discrepancy. Knee joint mobility and length measurement (compared with the contralateral), the average limited inflexion was 10 degrees (0 degrees to 20 degrees), the average limited straight was 4 degrees (0 degrees to 10), the average varus or valgus angle was 3 degrees (0 degrees to 5 degrees). KSS of the injured side was (96.4 +/- 5.0) points at final follow-up, 16 cases got excellent results and 1 good. All fractures obtained healing and no epiphyseal closed early was found. External fixator combined with limited internal fixation has advantages of simple operation, reliable fixation, early functional exercise in treating pediatric distal femurs fractures.

  2. Novel tilt-curvature coupling in lipid membranes

    Science.gov (United States)

    Terzi, M. Mert; Deserno, Markus

    2017-08-01

    On mesoscopic scales, lipid membranes are well described by continuum theories whose main ingredients are the curvature of a membrane's reference surface and the tilt of its lipid constituents. In particular, Hamm and Kozlov [Eur. Phys. J. E 3, 323 (2000)] have shown how to systematically derive such a tilt-curvature Hamiltonian based on the elementary assumption of a thin fluid elastic sheet experiencing internal lateral pre-stress. Performing a dimensional reduction, they not only derive the basic form of the effective surface Hamiltonian but also express its emergent elastic couplings as trans-membrane moments of lower-level material parameters. In the present paper, we argue, though, that their derivation unfortunately missed a coupling term between curvature and tilt. This term arises because, as one moves along the membrane, the curvature-induced change of transverse distances contributes to the area strain—an effect that was believed to be small but nevertheless ends up contributing at the same (quadratic) order as all other terms in their Hamiltonian. We illustrate the consequences of this amendment by deriving the monolayer and bilayer Euler-Lagrange equations for the tilt, as well as the power spectra of shape, tilt, and director fluctuations. A particularly curious aspect of our new term is that its associated coupling constant is the second moment of the lipid monolayer's lateral stress profile—which within this framework is equal to the monolayer Gaussian curvature modulus, κ¯ m. On the one hand, this implies that many theoretical predictions now contain a parameter that is poorly known (because the Gauss-Bonnet theorem limits access to the integrated Gaussian curvature); on the other hand, the appearance of κ¯ m outside of its Gaussian curvature provenance opens opportunities for measuring it by more conventional means, for instance by monitoring a membrane's undulation spectrum at short scales.

  3. Antibiotic susceptibility pattern of genital tract bacteria in pregnant women with preterm premature rupture of membranes in a resource-limited setting.

    Science.gov (United States)

    Eleje, George U; Adinma, Joseph I; Ghasi, Samuel; Ikechebelu, Joseph I; Igwegbe, Anthony O; Okonkwo, John E; Okafor, Charles I; Ezeama, Chukwuemeka O; Ezebialu, Ifeanyichukwu U; Ogbuagu, Chukwuanugo N

    2014-10-01

    To identify microbes prevalent in the genital tract of pregnant women with preterm premature rupture of membranes (PPROM) and to assess the susceptibility of the microbial isolates to a range of antibiotics to determine appropriate antibiotics for treating cases of PPROM in resource-limited settings. A prospective cross-sectional study was undertaken involving women with (n=105) and without (n=105) a confirmed diagnosis of PPROM admitted to Nnamdi Azikiwe University Teaching Hospital, southeast Nigeria, between January 1, 2011, and April 30, 2013. Endocervical swabs were collected from all participants and examined microbiologically. Antibiotic sensitivity testing was performed using Kirby-Bauer disk diffusion. Streptococcus spp., Staphylococcus aureus, and Escherichia coli were significantly more prevalent among women with PPROM than among those without PPROM (P<0.01). Among the antibiotics considered safe to use during pregnancy, the bacteria were most sensitive to ampicillin-sulbactam, cefixime, cefuroxime, and erythromycin. For the first 48hours, women with PPROM should receive an intravenous dose combining ampicillin-sulbactam, cefixime, cefuroxime, or erythromycin with metronidazole followed by oral administration of the chosen antibiotic combination to complete a 7-day course. Copyright © 2014 International Federation of Gynecology and Obstetrics. Published by Elsevier Ireland Ltd. All rights reserved.

  4. 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...

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

    KAUST Repository

    Hunt, Anton

    2015-09-01

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

  6. The effect of channel flow pattern on internal properties distribution of a proton exchange membrane fuel cell for cathode starvation conditions

    International Nuclear Information System (INIS)

    Ko, Dong Soo; Kang, Young Min; Yang, Jang Sik; Jeong, Ji Hwan; Choi, Gyung Min; Kim, Duck Jool

    2010-01-01

    The effect of channel flow pattern on the internal properties distribution of a proton exchange membrane fuel cell (PEMFC) for cathode starvation conditions in a unit cell was investigated through numerical studies and experiments. The polarization curves of a lab-scale mixed serpentine PEMFC were measured with increasing current loads for different cell temperatures (40, 50, and 60 .deg. C) at a relative humidity of 100%. To study the local temperature on the membrane, the water content in the MEA, and the gas velocity in terms of the channel type of the PEMFC with operating characteristics, numerical studies using the es-pemfc module of STAR-CD, which have been matched to the experimental data, were conducted in detail. The water content and velocity at the cathode channel bend of the mixed serpentine channel were relatively higher than those at the single and double channels. Conversely, the local temperature and mean temperature on the membrane of a single serpentine channel were the highest among all channels. These results can be used to design the PEMFC system, the channel flow field, and the cooling device

  7. Carbon membranes - current progress and future prospects

    International Nuclear Information System (INIS)

    Tennison, St.; Arnott, K.; Richter, H.

    2007-01-01

    The future use of nano-porous gas separation membranes will be dependent on significant reductions in the membrane and module costs, improvements in production methods to allow better reproducibility, ability to scale up production and improved performance and understanding of the mode of operation of the membrane systems. New approaches to ceramic supported carbon membranes could offer solutions to these problems. Whilst the performance characteristics underline the limitations of these membranes they also show where specific process opportunities might be accessible particularly in environmental and high temperature separations. (authors)

  8. Increasing selectivity of a heterogeneous ion-exchange membrane

    Czech Academy of Sciences Publication Activity Database

    Křivčík, J.; Neděla, D.; Hadrava, J.; Brožová, Libuše

    2015-01-01

    Roč. 56, č. 12 (2015), s. 3160-3166 ISSN 1944-3994. [International Conference on Membrane and Electromembrane Processes - MELPRO 2014. Prague, 18.05.2014-21.05.2014] Institutional support: RVO:61389013 Keywords : ion-exchange membrane * selectivity * permselectivity Subject RIV: JP - Industrial Processing Impact factor: 1.272, year: 2015

  9. Integral membrane protein structure determination using pseudocontact shifts

    Energy Technology Data Exchange (ETDEWEB)

    Crick, Duncan J.; Wang, Jue X. [University of Cambridge, Department of Biochemistry (United Kingdom); Graham, Bim; Swarbrick, James D. [Monash University, Monash Institute of Pharmaceutical Sciences (Australia); Mott, Helen R.; Nietlispach, Daniel, E-mail: dn206@cam.ac.uk [University of Cambridge, Department of Biochemistry (United Kingdom)

    2015-04-15

    Obtaining enough experimental restraints can be a limiting factor in the NMR structure determination of larger proteins. This is particularly the case for large assemblies such as membrane proteins that have been solubilized in a membrane-mimicking environment. Whilst in such cases extensive deuteration strategies are regularly utilised with the aim to improve the spectral quality, these schemes often limit the number of NOEs obtainable, making complementary strategies highly beneficial for successful structure elucidation. Recently, lanthanide-induced pseudocontact shifts (PCSs) have been established as a structural tool for globular proteins. Here, we demonstrate that a PCS-based approach can be successfully applied for the structure determination of integral membrane proteins. Using the 7TM α-helical microbial receptor pSRII, we show that PCS-derived restraints from lanthanide binding tags attached to four different positions of the protein facilitate the backbone structure determination when combined with a limited set of NOEs. In contrast, the same set of NOEs fails to determine the correct 3D fold. The latter situation is frequently encountered in polytopical α-helical membrane proteins and a PCS approach is thus suitable even for this particularly challenging class of membrane proteins. The ease of measuring PCSs makes this an attractive route for structure determination of large membrane proteins in general.

  10. Nonperturbative Renormalization Group Approach to Polymerized Membranes

    Science.gov (United States)

    Essafi, Karim; Kownacki, Jean-Philippe; Mouhanna, Dominique

    2014-03-01

    Membranes or membrane-like materials play an important role in many fields ranging from biology to physics. These systems form a very rich domain in statistical physics. The interplay between geometry and thermal fluctuations lead to exciting phases such flat, tubular and disordered flat phases. Roughly speaking, membranes can be divided into two group: fluid membranes in which the molecules are free to diffuse and thus no shear modulus. On the other hand, in polymerized membranes the connectivity is fixed which leads to elastic forces. This difference between fluid and polymerized membranes leads to a difference in their critical behaviour. For instance, fluid membranes are always crumpled, whereas polymerized membranes exhibit a phase transition between a crumpled phase and a flat phase. In this talk, I will focus only on polymerized phantom, i.e. non-self-avoiding, membranes. The critical behaviour of both isotropic and anisotropic polymerized membranes are studied using a nonperturbative renormalization group approach (NPRG). This allows for the investigation of the phase transitions and the low temperature flat phase in any internal dimension D and embedding d. Interestingly, graphene behaves just as a polymerized membrane in its flat phase.

  11. [Global public health: international health is tested to its limits by the human influenza A epidemic].

    Science.gov (United States)

    Franco-Giraldo, Alvaro; Alvarez-Dardet, Carlos

    2009-06-01

    This article comes from the intense international pressure that follows a near-catastrophy, such as the human influenza A H1N1 epidemic, and the limited resources for confronting such events. The analysis covers prevailing 20th century trends in the international public health arena and the change-induced challenges brought on by globalization, the transition set in motion by what has been deemed the "new" international public health and an ever-increasing focus on global health, in the context of an international scenario of shifting risks and opportunities and a growing number of multinational players. Global public health is defined as a public right, based on a new appreciation of the public, a new paradigm centered on human rights, and altruistic philosophy, politics, and ethics that undergird the changes in international public health on at least three fronts: redefining its theoretical foundation, improving world health, and renewing the international public health system, all of which is the byproduct of a new form of governance. A new world health system, directed by new global public institutions, would aim to make public health a global public right and face a variety of staggering challenges, such as working on public policy management on a global scale, renewing and democratizing the current global governing structure, and conquering the limits and weaknesses witnessed by international health.

  12. Employee Attitude to Management Style : case: International equitable association Nigeria Limited.

    OpenAIRE

    Osondu, Marshall

    2012-01-01

    The aim of the study is to reveal employees’ attitudes to management style in International equitable association Limited, Aba, Nigeria (IEA). IEA is a soap and detergent manufacturing company. The company uses modern management styles to drive employee performance. This study set out to investigate employee attitudes to the various management styles in use at IEA. The study used a framework which shows that employee attitude is driven by the employee’s awareness, the employee’s application o...

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

    Science.gov (United States)

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

    2010-02-09

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

  14. Determination of external and internal mass transfer limitation in nitrifying microbial aggregates.

    Science.gov (United States)

    Wilén, Britt-Marie; Gapes, Daniel; Keller, Jürg

    2004-05-20

    In this article we present a study of the effects of external and internal mass transfer limitation of oxygen in a nitrifying system. The oxygen uptake rates (OUR) were measured on both a macro-scale with a respirometric reactor using off-gas analysis (Titrimetric and Off-Gas Analysis (TOGA) sensor) and on a micro-scale with microsensors. These two methods provide independent, accurate measurements of the reaction rates and concentration profiles around and in the granules. The TOGA sensor and microsensor measurements showed a significant external mass transfer effect at low dissolved oxygen (DO) concentrations in the bulk liquid while it was insignificant at higher DO concentrations. The oxygen distribution with anaerobic or anoxic conditions in the center clearly shows major mass transfer limitation in the aggregate interior. The large drop in DO concentration of 22-80% between the bulk liquid and aggregate surface demonstrates that the external mass transfer resistance is also highly important. The maximum OUR even for floccular biomass was only attained at much higher DO concentrations (approximately 8 mg/L) than typically used in such systems. For granules, the DO required for maximal activity was estimated to be >20 mg/L, clearly indicating the effects of the major external and internal mass transfer limitations on the overall biomass activity. Smaller aggregates had a larger volumetric OUR indicating that the granules may have a lower activity in the interior part of the aggregate. Copyright 2004 Wiley Periodicals, Inc.

  15. Simulating the effect of SFCL on limiting the internal fault of synchronous machine

    International Nuclear Information System (INIS)

    Kheirizad, I; Varahram, M H; Jahed-Motlagh, M R; Rahnema, M; Mohammadi, A

    2008-01-01

    In this paper, we have modelled a synchronous generator with internal one phase to ground fault and then the performance of this machine with internal one phase to ground fault have been analyzed. The results show that if the faults occur in vicinity of machine's terminal, then we would have serious damages. To protect the machine from this kind of faults we have suggested integrating a SFCL (superconducting fault current limiter) into the machine's model. The results show that the fault currents in this case will reduce considerably without influencing the normal operation of the machine

  16. LONG-TERM RETROSPECTIVE ANALYSIS OF VISUAL ACUITY AND OPTICAL COHERENCE TOPOGRAPHIC CHANGES AFTER SINGLE VERSUS DOUBLE PEELING DURING VITRECTOMY FOR MACULAR EPIRETINAL MEMBRANES.

    Science.gov (United States)

    Jung, Jesse J; Hoang, Quan V; Ridley-Lane, Megan L; Sebrow, Dov B; Dhrami-Gavazi, Elona; Chang, Stanley

    2016-11-01

    To determine the long-term effect of internal limiting membrane with associated epiretinal membrane (ERM) peeling versus single peeling alone in terms of best-corrected visual acuity and anatomical outcomes on spectral-domain optical coherence tomography. This retrospective comparative cohort study of patients who had follow-up of >1 year and underwent surgery for ERM by a single surgeon (S.C.) from January 1, 2008 to December 31, 2012 compared cases in which the internal limiting membrane was stained with brilliant blue G to facilitate double peeling (n = 42) and single peeling (n = 43) of the ERM alone for up to 3 years of follow-up. For continuous variables, an independent two-tailed t-test was performed. For binary variables, the Fisher's exact test was performed. Statistical significance was defined as P peeling group were more likely to have ERM remaining in the central fovea postoperatively (P = 0.0020, becoming significant by postoperative Year 1, P = 0.022) and less likely to develop inner retinal dimpling (P = 0.000, becoming significant by postoperative Month 3, P = 0.015). At 3 years, central foveal thickness had decreased in the single-peeling group by -136.9 µm and by -84.1 μm in the double-peeling group, which was not significantly different (P = 0.08). Mean best-corrected visual acuity improved in both the groups at all time points. There was no statistically significant difference between the 2 groups at 3 years (P = 0.44; single-peeling group, 0.32 ± 0.42, Snellen 20/42; double-peeling group, 0.23 ± 0.27, Snellen 20/34). Brilliant blue G-assisted internal limiting membrane peeling for ERM results in a more thorough removal of residual ERM around the paracentral fovea. However, there is no difference in long-term best-corrected visual acuity at 3 years and a greater likelihood of inner retinal dimpling.

  17. Nanoengineered membranes for controlled transport

    Science.gov (United States)

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

    2010-01-05

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

  18. Limit loads for piping branch junctions under internal pressure and in-plane bending-Extended solutions

    International Nuclear Information System (INIS)

    Kim, Yun-Jae; Lee, Kuk-Hee; Park, Chi-Yong

    2008-01-01

    The authors have previously proposed plastic limit load solutions for thin-walled branch junctions under internal pressure and in-plane bending, based on finite element (FE) limit loads resulting from three-dimensional (3-D) FE limit analyses using elastic-perfectly plastic materials [Kim YJ, Lee KH, Park CY. Limit loads for thin-walled piping branch junctions under internal pressure and in-plane bending. Int J Press Vessels Piping 2006;83:645-53]. The solutions are valid for ratios of the branch-to-run pipe radius and thickness from 0.4 to 1.0, and for the mean radius-to-thickness ratio of the run pipe from 10.0 to 20.0. Moreover, the solutions considered the case of in-plane bending only on the branch pipe. This paper extends the previous solutions in two aspects. Firstly, plastic limit load solutions are given also for in-plane bending on the run pipe. Secondly, the validity of the proposed solutions is extended to ratios of the branch-to-run pipe radius and thickness from 0.0 to 1.0, and the mean radius-to-thickness ratio of the run pipe from 5.0 to 20.0. Comparisons with FE results show good agreement

  19. Detection of proteins on blot transfer membranes.

    Science.gov (United States)

    Sasse, Joachim; Gallagher, Sean R

    2003-11-01

    In the basic and alternate protocols of this unit, proteins are stained after electroblotting from polyacrylamide gels to blot transfer membranes. If the samples of interest are electrophoresed in duplicate and transferred to a blot transfer membrane, half of the membrane can be stained to determine the efficiency of transfer to the membrane and the other half can be used for immunoblotting (i.e., western blotting). Detection limits of each staining method are given along with a list of compatible blot transfer membranes and gels. A support protocol describes a method for alkali treatment that enhances subsequent staining of bound proteins.

  20. Two-dimensional stochastic modeling of membrane fouling

    NARCIS (Netherlands)

    Wessling, Matthias

    2001-01-01

    The phenomenon of fouling of microfiltration membranes by much smaller particles such as proteins is described by a new developed simulation algorithm based on diffusion limited aggregation simulation techniques. The model specifies the membrane morphology explicitly and allows to (a) characterize

  1. Ballistic impact response of lipid membranes.

    Science.gov (United States)

    Zhang, Yao; Meng, Zhaoxu; Qin, Xin; Keten, Sinan

    2018-03-08

    Therapeutic agent loaded micro and nanoscale particles as high-velocity projectiles can penetrate cells and tissues, thereby serving as gene and drug delivery vehicles for direct and rapid internalization. Despite recent progress in developing micro/nanoscale ballistic tools, the underlying biophysics of how fast projectiles deform and penetrate cell membranes is still poorly understood. To understand the rate and size-dependent penetration processes, we present coarse-grained molecular dynamics simulations of the ballistic impact of spherical projectiles on lipid membranes. Our simulations reveal that upon impact, the projectile can pursue one of three distinct pathways. At low velocities below the critical penetration velocity, projectiles rebound off the surface. At intermediate velocities, penetration occurs after the projectile deforms the membrane into a tubular thread. At very high velocities, rapid penetration occurs through localized membrane deformation without tubulation. Membrane tension, projectile velocity and size govern which phenomenon occurs, owing to their positive correlation with the reaction force generated between the projectile and the membrane during impact. Two critical membrane tension values dictate the boundaries among the three pathways for a given system, due to the rate dependence of the stress generated in the membrane. Our findings provide broad physical insights into the ballistic impact response of soft viscous membranes and guide design strategies for drug delivery through lipid membranes using micro/nanoscale ballistic tools.

  2. Preliminary studies of using preheated carrier gas for on-line membrane extraction of semivolatile organic compounds.

    Science.gov (United States)

    Liu, Xinyu; Pawliszyn, Janusz

    2007-04-01

    In this paper, we present results for the on-line determination of semivolatile organic compounds (SVOCs) in air using membrane extraction with a sorbent interface-ion mobility spectrometry (MESI-IMS) system with a preheated carrier (stripping) gas. The mechanism of the mass transfer of SVOCs across a membrane was initially studied. In comparison with the extraction of volatile analytes, the mass transfer resistance that originated from the slow desorption from the internal membrane surface during the SVOC extraction processes should be taken into account. A preheated carrier gas system was therefore built to facilitate desorption of analytes from the internal membrane surface. With the benefit of a temperature gradient existing between the internal and external membrane surfaces, an increase in the desorption rate of a specific analyte at the internal surface and the diffusion coefficient within the membrane could be achieved while avoiding a decrease of the distribution constant on the external membrane interface. This technique improved both the extraction rate and response times of the MESI-IMS system for the analysis of SVOCs. Finally, the MESI-IMS system was shown to be capable of on-site measurement by monitoring selected polynuclear aromatic hydrocarbons emitted from cigarette smoke.

  3. Evaluation of thin film ceria membranes for syngas membrane reactors—Preparation, characterization and testing

    DEFF Research Database (Denmark)

    Kaiser, Andreas; Foghmoes, Søren Preben Vagn; Chatzichristodoulou, Christodoulos

    2011-01-01

    Gadolinium doped ceria (Ce0.1Gd0.9O1.95−δ, CGO10) was investigated as oxygen separation membrane material for application in syngas production. Planar, thin film CGO10 membranes were fabricated by tape casting and lamination on porous NiO-YSZ supports and subsequent co-sintering. High oxygen fluxes......-stoichiometry profile in the 30μm thin CGO membrane under operation reveal that due to oxygen permeation in the membrane the largest non-stoichiometry at the permeate (fuel) side is more than a factor of 6 times smaller at 850°C than that expected for CGO10 at equilibrium. The related relative expansion of the thin...... film CGO membrane should therefore lie below the expansion limit of 0.1% expected to be critical for mechanical stability and thereby allows for operation at high temperatures and low oxygen partial pressures....

  4. HAMLET interacts with lipid membranes and perturbs their structure and integrity.

    Science.gov (United States)

    Mossberg, Ann-Kristin; Puchades, Maja; Halskau, Øyvind; Baumann, Anne; Lanekoff, Ingela; Chao, Yinxia; Martinez, Aurora; Svanborg, Catharina; Karlsson, Roger

    2010-02-23

    Cell membrane interactions rely on lipid bilayer constituents and molecules inserted within the membrane, including specific receptors. HAMLET (human alpha-lactalbumin made lethal to tumor cells) is a tumoricidal complex of partially unfolded alpha-lactalbumin (HLA) and oleic acid that is internalized by tumor cells, suggesting that interactions with the phospholipid bilayer and/or specific receptors may be essential for the tumoricidal effect. This study examined whether HAMLET interacts with artificial membranes and alters membrane structure. We show by surface plasmon resonance that HAMLET binds with high affinity to surface adherent, unilamellar vesicles of lipids with varying acyl chain composition and net charge. Fluorescence imaging revealed that HAMLET accumulates in membranes of vesicles and perturbs their structure, resulting in increased membrane fluidity. Furthermore, HAMLET disrupted membrane integrity at neutral pH and physiological conditions, as shown by fluorophore leakage experiments. These effects did not occur with either native HLA or a constitutively unfolded Cys-Ala HLA mutant (rHLA(all-Ala)). HAMLET also bound to plasma membrane vesicles formed from intact tumor cells, with accumulation in certain membrane areas, but the complex was not internalized by these vesicles or by the synthetic membrane vesicles. The results illustrate the difference in membrane affinity between the fatty acid bound and fatty acid free forms of partially unfolded HLA and suggest that HAMLET engages membranes by a mechanism requiring both the protein and the fatty acid. Furthermore, HAMLET binding alters the morphology of the membrane and compromises its integrity, suggesting that membrane perturbation could be an initial step in inducing cell death.

  5. Psychometrics and the neuroscience of individual differences: Internal consistency limits between-subjects effects.

    Science.gov (United States)

    Hajcak, Greg; Meyer, Alexandria; Kotov, Roman

    2017-08-01

    In the clinical neuroscience literature, between-subjects differences in neural activity are presumed to reflect reliable measures-even though the psychometric properties of neural measures are almost never reported. The current article focuses on the critical importance of assessing and reporting internal consistency reliability-the homogeneity of "items" that comprise a neural "score." We demonstrate how variability in the internal consistency of neural measures limits between-subjects (i.e., individual differences) effects. To this end, we utilize error-related brain activity (i.e., the error-related negativity or ERN) in both healthy and generalized anxiety disorder (GAD) participants to demonstrate options for psychometric analyses of neural measures; we examine between-groups differences in internal consistency, between-groups effect sizes, and between-groups discriminability (i.e., ROC analyses)-all as a function of increasing items (i.e., number of trials). Overall, internal consistency should be used to inform experimental design and the choice of neural measures in individual differences research. The internal consistency of neural measures is necessary for interpreting results and guiding progress in clinical neuroscience-and should be routinely reported in all individual differences studies. (PsycINFO Database Record (c) 2017 APA, all rights reserved).

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

    DEFF Research Database (Denmark)

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

    2017-01-01

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

  7. The liquid membrane for extraction of Yttrium and Dysprosium from Acid Nitric

    International Nuclear Information System (INIS)

    Johny, W.S.; Raldi-Artono-Koestoer; Kris-Tri-Basuki; Sudibyo

    1996-01-01

    The determination of surfactant in liquid membrane has been done. The surfactant is span-80 (sorbitol-monooleate), the liquid membrane phase was the organic phase (O), the internal liquid phase (W) with ratio O/W = 1, and surfactant. The organic phase using D 2 EHPA in the kerosene and the internal liquid phase using aqua des or acid nitric. The determination of surfactant with variation of span-80 (0,25 - 2%) in the liquid membrane volume. The speed of stirrer was 3500 rpm in 20 minute. The ratio of liquid membrane phase form and external phase (aqua des or acid nitric) was 1, the speed of stirrer was 350 rpm in 10 minute (permeation process). The liquid phase and the liquid membrane phase was separated and then determinated the volume of liquid membrane, the result of percentage of span-80 was 0,25 % volume. The extraction of yttrium and dysprosium in 2 M HNO 3 was Kd y = 2.945 and Kd D y = 0.019

  8. Role for chlamydial inclusion membrane proteins in inclusion membrane structure and biogenesis.

    Directory of Open Access Journals (Sweden)

    Jeffrey Mital

    Full Text Available The chlamydial inclusion membrane is extensively modified by the insertion of type III secreted effector proteins. These inclusion membrane proteins (Incs are exposed to the cytosol and share a common structural feature of a long, bi-lobed hydrophobic domain but little or no primary amino acid sequence similarity. Based upon secondary structural predictions, over 50 putative inclusion membrane proteins have been identified in Chlamydia trachomatis. Only a limited number of biological functions have been defined and these are not shared between chlamydial species. Here we have ectopically expressed several C. trachomatis Incs in HeLa cells and find that they induce the formation of morphologically distinct membranous vesicular compartments. Formation of these vesicles requires the bi-lobed hydrophobic domain as a minimum. No markers for various cellular organelles were observed in association with these vesicles. Lipid probes were incorporated by the Inc-induced vesicles although the lipids incorporated were dependent upon the specific Inc expressed. Co-expression of Inc pairs indicated that some colocalized in the same vesicle, others partially overlapped, and others did not associate at all. Overall, it appears that Incs may have an intrinsic ability to induce membrane formation and that individual Incs can induce membranous structures with unique properties.

  9. Use of nonwettable membranes for water transfer

    Science.gov (United States)

    Hausch, H. G.

    1970-01-01

    Transfer of water through nonwettable vinyl fluoride membranes has two unique features - /1/ very low water transfer rates can be held constant by holding temperature and solute concentrations constant, /2/ the pressure gradient against which water is transported is limited only by solution breakthrough or membrane strength.

  10. Modeling of interactions between nanoparticles and cell membranes

    Science.gov (United States)

    Ban, Young-Min

    containing the nanoparticles exhibit localized perturbation around the nanoparticle. The nanoparticles are not likely to affect membrane protein function by the weak perturbation of the internal stress in the membrane. Due to the short-ranged interactions between the nanoparticles, the nanoparticles would not form aggregates inside membranes. The effect of lipid peroxidation on cell membrane deformation is assessed. The peroxidized lipids introduce a perturbation to the internal structure of the membrane leading to higher amplitude of the membrane fluctuations. Higher concentration of the peroxidized lipids induces more significant perturbation. Cumulative effects of lipid peroxidation caused by nanoparticles are examined for the first time. The considered amphiphilic particle appears to reduce the perturbation of the membrane structure at its equilibrium position inside the peroxidized membrane. This suggests a possibility of antioxidant effect of the nanoparticle.

  11. Visual and anatomical outcomes following idiopathic macular epiretinal membrane surgery

    International Nuclear Information System (INIS)

    Shahzadi, B.; Rizvi, S.F.; Latif, K.; Naz, S.

    2016-01-01

    To assess the visual and anatomical outcomes following idiopathic macular epiretinal membrane (IERM) surgery. Study Design: Case series. Place and Duration of Study: Layton Rehmatulla Benevolent Trust (L.R.B.T), Free Base Eye Hospital, Karachi, from January 2015 to June 2016. Methodology: Thirty eyes of thirty patients affected with idiopathic macular epiretinal membrane stage 2 were enrolled in this study. They subsequently underwent 23-gauge pars plana vitrectomy (PPV) with epiretinal membrane removal without internal limiting membrane peeling. The visual outcome was measured as improvement in best corrected visual acuity (BCVA) of at least two or more lines on ETDRS chart as compared to preoperative BCVA. The anatomical outcome was measured as decrease in foveal thickness on Spectral Domain-Optical Coherence Tomography (SD-OCT). Patients were followed for a period of 06 months. Results: At the end of follow-ups, 23 (76%) eyes out of 30 gained 2 or more lines of vision. In 05 (16%) eyes, BCVA remained same and only 02 (6.6%) eyes showed worsening of vision. Mean preoperative foveal thickness was 392 ± 20 micro m, whereas mean postoperative thickness was 305 ± 16 micro m with an average decrease of 87 micro m, in foveal thickness. Recurrence of ERM was found to be the most frequent complication. Conclusion: IERM surgery is a safe procedure and beneficial in achieving significant visual acuity improvement and anatomical recovery in the majority of cases. (author)

  12. Metal ion separations using reactive membranes

    International Nuclear Information System (INIS)

    Way, J.D.

    1993-01-01

    A membrane is a barrier between two phases. If one component of a mixture moves through the membrane faster than another mixture component, a separation can be accomplished. Membranes are used commercially for many applications including gas separations, water purification, particle filtration, and macromolecule separations (Abelson). There are two points to note concerning this definition. First, a membrane is defined based on its function, not the material used to make the membrane. Secondly, a membrane separation is a rate process. The separation is accomplished by a driving force, not by equilibrium between phases. Liquids that are immiscible with the feed and product streams can also be used as membrane materials. Different solutes will have different solubilities and diffusion coefficients in a liquid. The product of the diffusivity and the solubility is known as the permeability coefficient, which is proportional to the solute flux. Differences in permeability coefficient will produce a separation between solutes at constant driving force. Because the diffusion coefficients in liquids are typically orders of magnitude higher than in polymers, a larger flux can be obtained. Further enhancements can be accomplished by adding a nonvolatile complexation agent to the liquid membrane. One can then have either coupled or facilitated transport of metal ions through a liquid membrane. The author describes two implementations of this concept, one involving a liquid membrane supported on a microporous membrane, and the other an emulsion liquid membrane, where separation occurs to internal receiving phases. Applications and costing studies for this technology are reviewed, and a brief summary of some of the problems with liquid membranes is presented

  13. Membrane Affinity of Platensimycin and Its Dialkylamine Analogs

    Directory of Open Access Journals (Sweden)

    Ian Rowe

    2015-08-01

    Full Text Available Membrane permeability is a desired property in drug design, but there have been difficulties in quantifying the direct drug partitioning into native membranes. Platensimycin (PL is a new promising antibiotic whose biosynthetic production is costly. Six dialkylamine analogs of PL were synthesized with identical pharmacophores but different side chains; five of them were found inactive. To address the possibility that their activity is limited by the permeation step, we calculated polarity, measured surface activity and the ability to insert into the phospholipid monolayers. The partitioning of PL and the analogs into the cytoplasmic membrane of E. coli was assessed by activation curve shifts of a re-engineered mechanosensitive channel, MscS, in patch-clamp experiments. Despite predicted differences in polarity, the affinities to lipid monolayers and native membranes were comparable for most of the analogs. For PL and the di-myrtenyl analog QD-11, both carrying bulky sidechains, the affinity for the native membrane was lower than for monolayers (half-membranes, signifying that intercalation must overcome the lateral pressure of the bilayer. We conclude that the biological activity among the studied PL analogs is unlikely to be limited by their membrane permeability. We also discuss the capacity of endogenous tension-activated channels to detect asymmetric partitioning of exogenous substances into the native bacterial membrane and the different contributions to the thermodynamic force which drives permeation.

  14. Tissue Banking in Malaysia-amniotic membrane

    International Nuclear Information System (INIS)

    Hashim bin Mohamad; Norimah binti Yusof

    1991-01-01

    Burn treatment using amniotic membranes in some of our patients initiate our own tissue bank starting with a pilot project on procurement, processing and clinical application of irradiated amniotic membrane. The irradiation of amniotic membrane was made possible by the availability of cobalt source at the Nuclear Energy Agency (UTN). With the technical help from the Inter-national Atomic Energy Agency (IAEA) we soon should be able to embark on bone bank to supply local surgeons. Thus the establishment of tissue bank at our institution will further enhance our programme which will include keratinocytes culture for burn, osteocytes culture for bone replacement as well as the use of animal skin for temporary coverage of open wounds

  15. Effective protection of biological membranes against photo-oxidative damage: Polymeric antioxidant forming a protecting shield over the membrane.

    Science.gov (United States)

    Mertins, Omar; Mathews, Patrick D; Gomide, Andreza B; Baptista, Mauricio S; Itri, Rosangela

    2015-10-01

    We have prepared a chitosan polymer modified with gallic acid in order to develop an efficient protection strategy biological membranes against photodamage. Lipid bilayers were challenged with photoinduced damage by photosensitization with methylene blue, which usually causes formation of hydroperoxides, increasing area per lipid, and afterwards allowing leakage of internal materials. The damage was delayed by a solution of gallic acid in a concentration dependent manner, but further suppressed by the polymer at very low concentrations. The membrane of giant unilamellar vesicles was covered with this modified macromolecule leading to a powerful shield against singlet oxygen and thus effectively protecting the lipid membrane from oxidative stress. The results have proven the discovery of a promising strategy for photo protection of biological membranes. Copyright © 2015 Elsevier B.V. All rights reserved.

  16. Cyanex based uranyl sensitive polymeric membrane electrodes.

    Science.gov (United States)

    Badr, Ibrahim H A; Zidan, W I; Akl, Z F

    2014-01-01

    Novel uranyl selective polymeric membrane electrodes were prepared using three different low-cost and commercially available Cyanex extractants namely, bis(2,4,4-trimethylpentyl) phosphinic acid [L1], bis(2,4,4-trimethylpentyl) monothiophosphinic acid [L2] and bis(2,4,4-trimethylpentyl) dithiophosphinic acid [L3]. Optimization and performance characteristics of the developed Cyanex based polymer membrane electrodes were determined. The influence of membrane composition (e.g., amount and type of ionic sites, as well as type of plasticizer) on potentiometric responses of the prepared membrane electrodes was studied. Optimized Cyanex-based membrane electrodes exhibited Nernstian responses for UO₂(2+) ion over wide concentration ranges with fast response times. The optimized membrane electrodes based on L1, L2 and L3 exhibited Nernstian responses towards uranyl ion with slopes of 29.4, 28.0 and 29.3 mV decade(-1), respectively. The optimized membrane electrodes based on L1-L3 showed detection limits of 8.3 × 10(-5), 3.0 × 10(-5) and 3.3 × 10(-6) mol L(-1), respectively. The selectivity studies showed that the optimized membrane electrodes exhibited high selectivity towards UO₂(2+) ion over large number of other cations. Membrane electrodes based on L3 exhibited superior potentiometric response characteristics compared to those based on L1 and L2 (e.g., widest linear range and lowest detection limit). The analytical utility of uranyl membrane electrodes formulated with Cyanex extractant L3 was demonstrated by the analysis of uranyl ion in different real samples for nuclear safeguards verification purposes. The results obtained using direct potentiometry and flow-injection methods were compared with those measured using the standard UV-visible and inductively coupled plasma spectroscopic methods. © 2013 Published by Elsevier B.V.

  17. Sweeping Gas Membrane Desalination Using Commercial Hydrophobic Hollow Fiber Membranes; TOPICAL

    International Nuclear Information System (INIS)

    EVANS, LINDSEY; MILLER, JAMES E.

    2002-01-01

    overcome this barrier, at least two improvements are required. First, new and different contactor geometries are necessary to achieve efficient contact with an extremely low pressure drop. Second, the temperature limits of the membranes must be increased. In the absence of these improvements, sweeping gas MD will not be economically competitive. However, the membranes may still find use in hybrid desalination systems

  18. Limitations of the colloidal silica method in mapping the endothelial plasma membrane proteome of the mouse heart.

    Science.gov (United States)

    Arjunan, Selvam; Reinartz, Michael; Emde, Barbara; Zanger, Klaus; Schrader, Jürgen

    2009-01-01

    The endothelial cell (EC) membrane is an important interface, which plays a crucial role in signal transduction. Our aim was to selectively purify luminal EC membrane proteins from the coronary vasculature of the isolated perfused mouse heart and analyze its composition with mass spectrometry (MS). To specifically label coronary ECs in the intact heart, the colloidal silica method was applied, which is based on the binding of positively charged colloidal silica to the surface of EC membranes. Transmission electron microscopy revealed the specific labeling of ECs of macro and microvessels. Two different methods of tissue homogenization (Teflon pestle and ultra blade) together with density centrifugation were used for membrane protein enrichment. Enrichment and purity was controlled by Western blot analysis using the EC-specific protein caveolin 1 and various intracellular marker proteins. The ultra blade method resulted in a tenfold enrichment of caveolin 1, while there was negligible contamination as judged by Western blot. However, protein yield was low and required pooling of ten hearts for MS. When enriched endothelial membrane proteins were digested with trypsin and analyzed by LC-MS, a total of 56 proteins could be identified, of which only 12 were membrane proteins. We conclude that coronary endothelial membranes can be conveniently labeled with colloidal silica. However, due to the ionic nature of interaction of colloidal silica with the EC membrane the shear rate required for cardiac homogenization resulted in a substantial loss of specificity.

  19. Ion beam heating of thin silicon membranes

    International Nuclear Information System (INIS)

    Tissot, P.E.; Hart, R.R.

    1993-01-01

    For silicon membranes irradiated by an ion beam in a vacuum environment, such as the masks used for ion beam lithography and the membranes used for thin film self-annealing, the heat transfer modes are radiation and limited conduction through the thin membrane. The radiation component depends on the total hemispherical emissivity which varies with the thickness and temperature of the membrane. A semiempirical correlation for the absorption coefficient of high resistivity silicon was derived and the variation of the total emissivity with temperature was computed for membranes with thicknesses between 0.1 and 10 μm. Based on this result, the temperatures reached during exposure to ion beams of varying intensities were computed. A proper modeling of the emissivity is shown to be important for beam heating of thin silicon membranes. (orig.)

  20. Multi-layer membrane model for mass transport in a direct ethanol fuel cell using an alkaline anion exchange membrane

    Science.gov (United States)

    Bahrami, Hafez; Faghri, Amir

    2012-11-01

    A one-dimensional, isothermal, single-phase model is presented to investigate the mass transport in a direct ethanol fuel cell incorporating an alkaline anion exchange membrane. The electrochemistry is analytically solved and the closed-form solution is provided for two limiting cases assuming Tafel expressions for both oxygen reduction and ethanol oxidation. A multi-layer membrane model is proposed to properly account for the diffusive and electroosmotic transport of ethanol through the membrane. The fundamental differences in fuel crossover for positive and negative electroosmotic drag coefficients are discussed. It is found that ethanol crossover is significantly reduced upon using an alkaline anion exchange membrane instead of a proton exchange membrane, especially at current densities higher than 500 A m

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

    Science.gov (United States)

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

    2015-01-01

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

  2. Overcoming bottlenecks in the membrane protein structural biology pipeline.

    Science.gov (United States)

    Hardy, David; Bill, Roslyn M; Jawhari, Anass; Rothnie, Alice J

    2016-06-15

    Membrane proteins account for a third of the eukaryotic proteome, but are greatly under-represented in the Protein Data Bank. Unfortunately, recent technological advances in X-ray crystallography and EM cannot account for the poor solubility and stability of membrane protein samples. A limitation of conventional detergent-based methods is that detergent molecules destabilize membrane proteins, leading to their aggregation. The use of orthologues, mutants and fusion tags has helped improve protein stability, but at the expense of not working with the sequence of interest. Novel detergents such as glucose neopentyl glycol (GNG), maltose neopentyl glycol (MNG) and calixarene-based detergents can improve protein stability without compromising their solubilizing properties. Styrene maleic acid lipid particles (SMALPs) focus on retaining the native lipid bilayer of a membrane protein during purification and biophysical analysis. Overcoming bottlenecks in the membrane protein structural biology pipeline, primarily by maintaining protein stability, will facilitate the elucidation of many more membrane protein structures in the near future. © 2016 The Author(s). published by Portland Press Limited on behalf of the Biochemical Society.

  3. A surgical simulator for peeling the inner limiting membrane during wet conditions.

    Science.gov (United States)

    Omata, Seiji; Someya, Yusei; Adachi, Shyn'ya; Masuda, Taisuke; Hayakawa, Takeshi; Harada, Kanako; Mitsuishi, Mamoru; Totsuka, Kiyohito; Araki, Fumiyuki; Takao, Muneyuki; Aihara, Makoto; Arai, Fumihito

    2018-01-01

    The present study was performed to establish a novel ocular surgery simulator for training in peeling of the inner limited membrane (ILM). This simulator included a next-generation artificial ILM with mechanical properties similar to the natural ILM that could be peeled underwater in the same manner as in actual surgery. An artificial eye consisting of a fundus and eyeball parts was fabricated. The artificial eye was installed in the eye surgery simulator. The fundus part was mounted in the eyeball, which consisted of an artificial sclera, retina, and ILM. To measure the thickness of the fabricated ILM on the artificial retina, we calculated the distance of the step height as the thickness of the artificial ILM. Two experienced ophthalmologists then assessed the fabricated ILM by sensory evaluation. The minimum thickness of the artificial ILM was 1.9 ± 0.3 μm (n = 3). We were able to perform the peeling task with the ILM in water. Based on the sensory evaluation, an ILM with a minimum thickness and 1000 degrees of polymerization was suitable for training. We installed the eye model on an ocular surgery simulator, which allowed for the performance of a sequence of operations similar to ILM peeling. In conclusion, we developed a novel ocular surgery simulator for ILM peeling. The artificial ILM was peeled underwater in the same manner as in an actual operation.

  4. Application of membrane technologies for liquid radioactive waste processing

    International Nuclear Information System (INIS)

    2004-01-01

    Membrane separation processes have made impressive progress since the first synthesis of membranes almost 40 years ago. This progress was driven by strong technological needs and commercial expectations. As a result the range of successful applications of membranes and membrane processes is continuously broadening. In addition, increasing application of membrane processes and technologies lies in the increasing variations of the nature and characteristics of commercial membranes and membrane apparatus. The objective of the report is to review the information on application of membrane technologies in the processing of liquid radioactive waste. The report covers the various types of membranes, equipment design, range of applications, operational experience and the performance characteristics of different membrane processes. The report aims to provide Member States with basic information on the applicability and limitations of membrane separation technologies for processing liquid radioactive waste streams

  5. Sphingolipid topology and the dynamic organization and function of membrane proteins

    NARCIS (Netherlands)

    van Meer, G.|info:eu-repo/dai/nl/068570368; Hoetzl, S.

    2010-01-01

    When acquiring internal membranes and vesicular transport, eukaryotic cells started to synthesize sphingolipids and sterols. The physical differences between these and the glycerophospholipids must have enabled the cells to segregate lipids in the membrane plane. Localizing this event to the Golgi

  6. Cytoskeletal Components Define Protein Location to Membrane Microdomains*

    Science.gov (United States)

    Szymanski, Witold G.; Zauber, Henrik; Erban, Alexander; Gorka, Michal; Wu, Xu Na; Schulze, Waltraud X.

    2015-01-01

    The plasma membrane is an important compartment that undergoes dynamic changes in composition upon external or internal stimuli. The dynamic subcompartmentation of proteins in ordered low-density (DRM) and disordered high-density (DSM) membrane phases is hypothesized to require interactions with cytoskeletal components. Here, we systematically analyzed the effects of actin or tubulin disruption on the distribution of proteins between membrane density phases. We used a proteomic screen to identify candidate proteins with altered submembrane location, followed by biochemical or cell biological characterization in Arabidopsis thaliana. We found that several proteins, such as plasma membrane ATPases, receptor kinases, or remorins resulted in a differential distribution between membrane density phases upon cytoskeletal disruption. Moreover, in most cases, contrasting effects were observed: Disruption of actin filaments largely led to a redistribution of proteins from DRM to DSM membrane fractions while disruption of tubulins resulted in general depletion of proteins from the membranes. We conclude that actin filaments are necessary for dynamic movement of proteins between different membrane phases and that microtubules are not necessarily important for formation of microdomains as such, but rather they may control the protein amount present in the membrane phases. PMID:26091700

  7. Discriminatory Role of Detergent-Resistant Membranes in the Dimerization and Endocytosis of Prostate-Specific Membrane Antigen

    Science.gov (United States)

    Schmidt, Sonja; Gericke, Birthe; Fracasso, Giulio; Ramarli, Dunia; Colombatti, Marco; Naim, Hassan Y.

    2013-01-01

    Prostate-specific membrane antigen (PSMA) is a type-II membrane glycoprotein that was initially identified in LNCaP cells. It is expressed at elevated levels in prostate cancer. In view of the correlation between the expression levels of PSMA and disease grade and stage, PSMA is considered to be one of the most promising biomarkers in the diagnosis and treatment of prostate cancer. In LNCaP cells PSMA undergoes internalization via clathrin-coated pits followed by accumulation in the endosomes. PSMA associates with different types of detergent-resistant membranes (DRMs) along the secretory pathway. Its mature form is mainly insoluble in Lubrol WX, but does not associate with Triton X-100-DRMs. To understand the mechanism of PSMA internalization we investigated its association during internalization with DRMs. For this purpose, internalization was induced by antibody cross-linking. We demonstrate at the biochemical and cell biological levels that: [i] exclusively homodimers of PSMA are associated with Lubrol WX-DRMs, [ii] antibody-induced cross-linking of PSMA molecules results in a time-dependent partitioning into another DRMs type, namely Triton X-100-DRMs, and [iii] concomitant with its association with Triton-X-100-DRMs internalization of PSMA occurs along tubulin filaments. In a previous work (Colombatti et al. (2009) PLoS One 4: e4608) we demonstrated that the small GTPases RAS and RAC1 and the MAPKs p38 and ERK1/2 are activated during antibody cross-linking. As downstream effects of this activation we observed a strong induction of NF-kB associated with an increased expression of IL-6 and CCL5 genes and that IL-6 and CCL5 enhanced the proliferative potential of LNCaP cells synergistically. These observations together with findings reported here hypothesize a fundamental role of DRMs during activation of PSMA as platforms for trafficking, endocytosis and signalling. Understanding these mechanisms constitutes an essential prerequisite for utilization of PSMA as

  8. Discriminatory Role of Detergent-Resistant Membranes in the Dimerization and Endocytosis of Prostate-Specific Membrane Antigen.

    Directory of Open Access Journals (Sweden)

    Sonja Schmidt

    Full Text Available Prostate-specific membrane antigen (PSMA is a type-II membrane glycoprotein that was initially identified in LNCaP cells. It is expressed at elevated levels in prostate cancer. In view of the correlation between the expression levels of PSMA and disease grade and stage, PSMA is considered to be one of the most promising biomarkers in the diagnosis and treatment of prostate cancer. In LNCaP cells PSMA undergoes internalization via clathrin-coated pits followed by accumulation in the endosomes. PSMA associates with different types of detergent-resistant membranes (DRMs along the secretory pathway. Its mature form is mainly insoluble in Lubrol WX, but does not associate with Triton X-100-DRMs. To understand the mechanism of PSMA internalization we investigated its association during internalization with DRMs. For this purpose, internalization was induced by antibody cross-linking. We demonstrate at the biochemical and cell biological levels that: [i] exclusively homodimers of PSMA are associated with Lubrol WX-DRMs, [ii] antibody-induced cross-linking of PSMA molecules results in a time-dependent partitioning into another DRMs type, namely Triton X-100-DRMs, and [iii] concomitant with its association with Triton-X-100-DRMs internalization of PSMA occurs along tubulin filaments. In a previous work (Colombatti et al. (2009 PLoS One 4: e4608 we demonstrated that the small GTPases RAS and RAC1 and the MAPKs p38 and ERK1/2 are activated during antibody cross-linking. As downstream effects of this activation we observed a strong induction of NF-kB associated with an increased expression of IL-6 and CCL5 genes and that IL-6 and CCL5 enhanced the proliferative potential of LNCaP cells synergistically. These observations together with findings reported here hypothesize a fundamental role of DRMs during activation of PSMA as platforms for trafficking, endocytosis and signalling. Understanding these mechanisms constitutes an essential prerequisite for

  9. A Review on Catalytic Membranes Production and Applications

    Directory of Open Access Journals (Sweden)

    Heba Abdallah

    2017-05-01

    Full Text Available The development of the chemical industry regarding reducing the production cost and obtaining a high-quality product with low environmental impact became the essential requirements of the world in these days. The catalytic membrane is considered as one of the new alternative solutions of catalysts problems in the industries, where the reaction and separation can be amalgamated in one unit. The catalytic membrane has numerous advantages such as breaking the thermodynamic equilibrium limitation, increasing conversion rate, reducing the recycle and separation costs. But the limitation or most disadvantages of catalytic membranes related to the high capital costs for fabrication or the fact that manufacturing process is still under development. This review article summarizes the most recent advances and research activities related to preparation, characterization, and applications of catalytic membranes. In this article, various types of catalytic membranes are displayed with different applications and explained the positive impacts of using catalytic membranes in various reactions. Copyright © 2017 BCREC Group. All rights reserved. Received: 1st April 2016; Revised: 14th February 2017; Accepted: 22nd February 2017 How to Cite: Abdallah, H. (2017. A Review on Catalytic Membranes Production and Applications. Bulletin of Chemical Reaction Engineering & Catalysis, 12 (2: 136-156 (doi:10.9767/bcrec.12.2.462.136-156 Permalink/DOI: http://dx.doi.org/10.9767/bcrec.12.2.462.136-156

  10. Concerted diffusion of lipids in raft-like membranes

    NARCIS (Netherlands)

    Apajalahti, Touko; Niemela, Perttu; Govindan, Praveen Nedumpully; Miettinen, Markus S.; Salonen, Emppu; Marrink, Siewert-Jan; Vattulainen, Ilpo

    2010-01-01

    Currently, there is no comprehensive model for the dynamics of cellular membranes. The understanding of even the basic dynamic processes, such as lateral diffusion of lipids, is still quite limited. Recent studies of one-component membrane systems have shown that instead of single-particle motions,

  11. Counter-current membrane reactor for WGS process: Membrane design

    Energy Technology Data Exchange (ETDEWEB)

    Piemonte, Vincenzo; Favetta, Barbara [Department of Chemical Engineering Materials and Environment, University of Rome ' ' La Sapienza' ' , via Eudossiana 18, 00184 Rome (Italy); De Falco, Marcello [Faculty of Engineering, University Campus Bio-Medico of Rome, via Alvaro del Portillo 21, 00128 Rome (Italy); Basile, Angelo [CNR-ITM, c/o University of Calabria, Via Pietro Bucci, Cubo 17/C, 87030 Rende (CS) (Italy)

    2010-11-15

    Water gas shift (WGS) is a thermodynamically limited reaction which has to operate at low temperatures, reducing kinetics rate and increasing the amount of catalyst required to reach valuable CO conversions. It has been widely demonstrated that the integration of hydrogen selective membranes is a promising way to enhance WGS reactors performance: a Pd-based MR operated successfully overcoming the thermodynamic constraints of a traditional reactor thanks to the removal of hydrogen from reaction environment. In the first part of a MR, the H{sub 2} partial pressure starts from a minimum value since the reaction has not started. As a consequence, if the carrier gas in the permeation zone is sent in counter-current, which is the most efficient configuration, in the first reactor section the H{sub 2} partial pressure in reaction zone is low while in the permeation zone is high, potentially implying back permeation. This means a bad utilization of the first part of the membrane area and thus, a worsening of the MR performance with lower H{sub 2} recovery and lower CO conversion with respect to the case in which the whole selective surface is properly used. To avoid this problem different MR configurations were evaluated by a 1-D pseudo-homogeneous model, validated with WGS industrial data reported in scientific literature. It was demonstrated that the permeated H{sub 2} flow rate per membrane surface, i.e. the membrane flux, strongly improves if selective membrane is placed only in the second part of the reactor: in fact, if the membrane is placed at L{sub m}/L{sub tot} = 0.5, the membrane flux is 0.2 kmol/(m{sup 2}h) about, if it is placed along all reactor tube (L{sub m}/L{sub tot} = 1), flux is 0.05 kmol/(m{sup 2}h). The effect of the L/D reactor ratio and of the reactor wall temperature on the CO conversion were also assessed. (author)

  12. Membrane cholesterol regulates lysosome-plasma membrane fusion events and modulates Trypanosoma cruzi invasion of host cells.

    Directory of Open Access Journals (Sweden)

    Bárbara Hissa

    Full Text Available BACKGROUND: Trypomastigotes of Trypanosoma cruzi are able to invade several types of non-phagocytic cells through a lysosomal dependent mechanism. It has been shown that, during invasion, parasites trigger host cell lysosome exocytosis, which initially occurs at the parasite-host contact site. Acid sphingomyelinase released from lysosomes then induces endocytosis and parasite internalization. Lysosomes continue to fuse with the newly formed parasitophorous vacuole until the parasite is completely enclosed by lysosomal membrane, a process indispensable for a stable infection. Previous work has shown that host membrane cholesterol is also important for the T. cruzi invasion process in both professional (macrophages and non-professional (epithelial phagocytic cells. However, the mechanism by which cholesterol-enriched microdomains participate in this process has remained unclear. METHODOLOGY/PRINCIPAL FINDING: In the present work we show that cardiomyocytes treated with MβCD, a drug able to sequester cholesterol from cell membranes, leads to a 50% reduction in invasion by T. cruzi trypomastigotes, as well as a decrease in the number of recently internalized parasites co-localizing with lysosomal markers. Cholesterol depletion from host membranes was accompanied by a decrease in the labeling of host membrane lipid rafts, as well as excessive lysosome exocytic events during the earlier stages of treatment. Precocious lysosomal exocytosis in MβCD treated cells led to a change in lysosomal distribution, with a reduction in the number of these organelles at the cell periphery, and probably compromises the intracellular pool of lysosomes necessary for T. cruzi invasion. CONCLUSION/SIGNIFICANCE: Based on these results, we propose that cholesterol depletion leads to unregulated exocytic events, reducing lysosome availability at the cell cortex and consequently compromise T. cruzi entry into host cells. The results also suggest that two different pools of

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

    KAUST Repository

    Hilke, Roland

    2014-12-01

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

  14. Measuring shape fluctuations in biological membranes

    International Nuclear Information System (INIS)

    Monzel, C; Sengupta, K

    2016-01-01

    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. (topical review)

  15. Analytical model of internally coupled ears

    DEFF Research Database (Denmark)

    Vossen, Christine; Christensen-Dalsgaard, Jakob; Leo van Hemmen, J

    2010-01-01

    Lizards and many birds possess a specialized hearing mechanism: internally coupled ears where the tympanic membranes connect through a large mouth cavity so that the vibrations of the tympanic membranes influence each other. This coupling enhances the phase differences and creates amplitude...... additionally provides the opportunity to incorporate the effect of the asymmetrically attached columella, which leads to the activation of higher membrane vibration modes. Incorporating this effect, the analytical model can explain measurements taken from the tympanic membrane of a living lizard, for example...

  16. ALTERNATIVE MATERIALS TO PD MEMBRANES FOR HYDROGEN PURIFICATION

    Energy Technology Data Exchange (ETDEWEB)

    Korinko, P; T. Adams

    2008-09-12

    Development of advanced hydrogen separation membranes in support of hydrogen production processes such as coal gasification and as front end gas purifiers for fuel cell based system is paramount to the successful implementation of a national hydrogen economy. Current generation metallic hydrogen separation membranes are based on Pd-alloys. Although the technology has proven successful, at issue is the high cost of palladium. Evaluation of non-noble metal based dense metallic separation membranes is currently receiving national and international attention. The focal point of the reported work was to evaluate two different classes of materials for potential replacement of conventional Pd-alloy purification/diffuser membranes. Crystalline V-Ni-Ti and Amorphous Fe- and Co-based metallic glass alloys have been evaluated using gaseous hydrogen permeation testing techniques.

  17. Analytical Investigation of the Limits for the In-Plane Thermal Conductivity Measurement Using a Suspended Membrane Setup

    Science.gov (United States)

    Linseis, V.; Völklein, F.; Reith, H.; Woias, P.; Nielsch, K.

    2018-06-01

    An analytical study has been performed on the measurement capabilities of a 100-nm thin suspended membrane setup for the in-plane thermal conductivity measurements of thin film samples using the 3 ω measurement technique, utilizing a COSMOL Multiphysics simulation. The maximum measurement range under observance of given boundary conditions has been studied. Three different exemplary sample materials, with a thickness from the nanometer to the micrometer range and a thermal conductivity from 0.4 W/mK up to 100 W/mK have been investigated as showcase studies. The results of the simulations have been compared to a previously published evaluation model, in order to determine the deviation between both and thereby the measurement limit. As thermal transport properties are temperature dependent, all calculations refer to constant room temperature conditions.

  18. Spectral imaging toolbox: segmentation, hyperstack reconstruction, and batch processing of spectral images for the determination of cell and model membrane lipid order.

    Science.gov (United States)

    Aron, Miles; Browning, Richard; Carugo, Dario; Sezgin, Erdinc; Bernardino de la Serna, Jorge; Eggeling, Christian; Stride, Eleanor

    2017-05-12

    Spectral imaging with polarity-sensitive fluorescent probes enables the quantification of cell and model membrane physical properties, including local hydration, fluidity, and lateral lipid packing, usually characterized by the generalized polarization (GP) parameter. With the development of commercial microscopes equipped with spectral detectors, spectral imaging has become a convenient and powerful technique for measuring GP and other membrane properties. The existing tools for spectral image processing, however, are insufficient for processing the large data sets afforded by this technological advancement, and are unsuitable for processing images acquired with rapidly internalized fluorescent probes. Here we present a MATLAB spectral imaging toolbox with the aim of overcoming these limitations. In addition to common operations, such as the calculation of distributions of GP values, generation of pseudo-colored GP maps, and spectral analysis, a key highlight of this tool is reliable membrane segmentation for probes that are rapidly internalized. Furthermore, handling for hyperstacks, 3D reconstruction and batch processing facilitates analysis of data sets generated by time series, z-stack, and area scan microscope operations. Finally, the object size distribution is determined, which can provide insight into the mechanisms underlying changes in membrane properties and is desirable for e.g. studies involving model membranes and surfactant coated particles. Analysis is demonstrated for cell membranes, cell-derived vesicles, model membranes, and microbubbles with environmentally-sensitive probes Laurdan, carboxyl-modified Laurdan (C-Laurdan), Di-4-ANEPPDHQ, and Di-4-AN(F)EPPTEA (FE), for quantification of the local lateral density of lipids or lipid packing. The Spectral Imaging Toolbox is a powerful tool for the segmentation and processing of large spectral imaging datasets with a reliable method for membrane segmentation and no ability in programming required. The

  19. Membrane trafficking pathways and their roles in plant-microbe interactions.

    Science.gov (United States)

    Inada, Noriko; Ueda, Takashi

    2014-04-01

    Membrane trafficking functions in the delivery of proteins that are newly synthesized in the endoplasmic reticulum (ER) to their final destinations, such as the plasma membrane (PM) and the vacuole, and in the internalization of extracellular components or PM-associated proteins for recycling or degradative regulation. These trafficking pathways play pivotal roles in the rapid responses to environmental stimuli such as challenges by microorganisms. In this review, we provide an overview of the current knowledge of plant membrane trafficking and its roles in plant-microbe interactions. Although there is little information regarding the mechanism of pathogenic modulation of plant membrane trafficking thus far, recent research has identified many membrane trafficking factors as possible targets of microbial modulation.

  20. Cholesterol asymmetry in synaptic plasma membranes.

    Science.gov (United States)

    Wood, W Gibson; Igbavboa, Urule; Müller, Walter E; Eckert, Gunter P

    2011-03-01

    Lipids are essential for the structural and functional integrity of membranes. Membrane lipids are not randomly distributed but are localized in different domains. A common characteristic of these membrane domains is their association with cholesterol. Lipid rafts and caveolae are examples of cholesterol enriched domains, which have attracted keen interest. However, two other important cholesterol domains are the exofacial and cytofacial leaflets of the plasma membrane. The two leaflets that make up the bilayer differ in their fluidity, electrical charge, lipid distribution, and active sites of certain proteins. The synaptic plasma membrane (SPM) cytofacial leaflet contains over 85% of the total SPM cholesterol as compared with the exofacial leaflet. This asymmetric distribution of cholesterol is not fixed or immobile but can be modified by different conditions in vivo: (i) chronic ethanol consumption; (ii) statins; (iii) aging; and (iv) apoE isoform. Several potential candidates have been proposed as mechanisms involved in regulation of SPM cholesterol asymmetry: apoE, low-density lipoprotein receptor, sterol carrier protein-2, fatty acid binding proteins, polyunsaturated fatty acids, P-glycoprotein and caveolin-1. This review examines cholesterol asymmetry in SPM, potential mechanisms of regulation and impact on membrane structure and function. © 2011 The Authors. Journal of Neurochemistry © 2011 International Society for Neurochemistry.

  1. Comparing the short and long term stability of biodegradable, ceramic and cation exchange membranes in microbial fuel cells.

    Science.gov (United States)

    Winfield, Jonathan; Chambers, Lily D; Rossiter, Jonathan; Ieropoulos, Ioannis

    2013-11-01

    The long and short-term stability of two porous dependent ion exchange materials; starch-based compostable bags (BioBag) and ceramic, were compared to commercially available cation exchange membrane (CEM) in microbial fuel cells. Using bi-directional polarisation methods, CEM exhibited power overshoot during the forward sweep followed by significant power decline over the reverse sweep (38%). The porous membranes displayed no power overshoot with comparably smaller drops in power during the reverse sweep (ceramic 8%, BioBag 5.5%). The total internal resistance at maximum power increased by 64% for CEM compared to 4% (ceramic) and 6% (BioBag). Under fixed external resistive loads, CEM exhibited steeper pH reductions than the porous membranes. Despite its limited lifetime, the BioBag proved an efficient material for a stable microbial environment until failing after 8 months, due to natural degradation. These findings highlight porous separators as ideal candidates for advancing MFC technology in terms of cost and operation stability. Copyright © 2013 Elsevier Ltd. All rights reserved.

  2. Porphyrin-functionalized porous polysulfone membrane towards an optical sensor membrane for sorption and detection of cadmium(II)

    Energy Technology Data Exchange (ETDEWEB)

    Zhao, Lizhi, E-mail: zhaolizhi_phd@163.com [State Key Laboratory of Separation Membranes and Membrane Processes, School of Materials Science and Engineering, Tianjin Polytechnic University, Tianjin 300387 (China); Li, Min; Liu, Manman; Zhang, Yuecong [State Key Laboratory of Separation Membranes and Membrane Processes, School of Materials Science and Engineering, Tianjin Polytechnic University, Tianjin 300387 (China); Wu, Chenglin [School of Pharmaceutical and Chemical Engineering, Taizhou University, Taizhou 317000, Zhejiang Province (China); Zhang, Yuzhong, E-mail: zhangyz2004cn@163.com [State Key Laboratory of Separation Membranes and Membrane Processes, School of Materials Science and Engineering, Tianjin Polytechnic University, Tianjin 300387 (China)

    2016-01-15

    Highlights: • An optical sensor membrane is prepared by TMPyP and PNaSS-grafted PSF membrane. • The optical sensor membrane shows enhanced sorption for cadmium(II). • Visual and spectrophotometric detection can be achieved. • The functional membrane exhibits good stability and reusability. - Abstract: In this study, an optical sensor membrane was prepared for sorption and detection of cadmium(II) (Cd(II)) in aqueous solution. A polyanion, poly(sodium 4-styrenesulfonate) (PNaSS), was grafted onto the chloromethylated polysulfone (CMPSF) microporous membrane via surface-initiated ATRP. 5,10,15,20-tetrakis(4-N-methylpyridyl) porphyrin p-toluenesulfonate (TMPyP) was immobilized onto the PNaSS-grafted polysulfone (PSF-PNaSS) membrane through electrostatic interaction. The TMPyP-functionalized membrane exhibited an enhanced sorption for, and distinct color and spectral response to cadmium(II) (Cd(II)) in aqueous solution. Larger immobilization capacity of TMPyP on the membrane led to stronger sorption for Cd(II), and smaller one made the optical sensor have a faster (in minutes) and more sensitive response to the ion. The detection limit study indicated that the functional membrane with proper amount of TMPyP (<0.5 mg/g) could still have color and spectral response to Cd(II) solutions at an extreme low concentration (10{sup −4} mg/L). The optical sensor membrane exhibited good stability and reusability which made it efficient for various sorptive removal and detection applications.

  3. USE OF MEMBRANE EMULSION SPAN 80 AND TOPO IN URANIUM EXTRACTION AND STRIPPING

    Directory of Open Access Journals (Sweden)

    Kris Tri Basuki

    2017-01-01

    Full Text Available ABSTRACT USE OF MEMBRANE EMULSION SPAN 80 AND TOPO IN URANIUM EXTRACTION AND STRIPPING. Membrane emulsion span 80 and TOPO used in uranium extraction and stripping has been done. The extraction was carried outby emulsion membrane H3PO4 in TOPO-Kerosene. The feed or external aqueous phase was uranium in  HNO3. The emulgator span-80 was used to obtain a stable emulsion membrane system. The influence factors were percentage of TOPO-Kerosene, time extraction,  molarity of external aqueous phase and  molarity of internal aqueous. After the emulsion membrane was formed, the extractionand stripping process was performed. The ratio volume feed : volume membrane phase equal to 1 : 1 and volume of 5 % TOPO-Kerosene : Volume 3 M H3PO4 equal 1 : 1 were used. The relative good yield were obtained at concentration of TOPO in Kerosene and 3 M H3PO4 was 5 %, molarity of internal aqueous phase equal to 1 M, molarity of external aqueous phase 3 M H3PO4 and time extraction equalto 10 minutes with the speed of emulsification was 8000 rpm. At this condition the extraction efficiency of uranium obtained was 97.8 %, the stripping efficiency 52.56 %, and the total efficiency was 53.80 %. Keywords: membrane emulsion, extraction, stripping, span 80, kerosene, uranium. ABSTRAK PENGGUNAAN MEMBRAN EMULSI SPAN 80 DAN TOPO UNTUK EKSTRASI DAN STRIPPING URANIUM. Telah dilakukan penelitian membran emulsi span 80 dan TOPO yang digunakan untuk ekstraksi uranium. Extraksi dengan membran emulsi H3PO4 dalam TOPO-Kerosen. Larutan umpan untuk fasa air eksternal adalah uranium dalam asam nitrat. Untuk memperoleh sistem emulsi yang stabil dipakai emulgator Span 80. Parameter yang berpengaruh adalah persen TOPO-Kerosene, molaritas fasa air internal H3PO4, molaritas fasa air eksternal HNO3 dan waktu ekstraksi. Setelah diperoleh membran emulsi, kemudian dilakukan proses ekstraksi dan stripping, dengan rasio volume umpan : volume membran sebesar 1 : 1; volume 5% TOPO-Kerose : volume 3M

  4. Combination of Electrochemical Processes with Membrane Bioreactors for Wastewater Treatment and Fouling Control: A Review

    OpenAIRE

    Ensano, Benny M. B.; Borea, Laura; Naddeo, Vincenzo; Belgiorno, Vincenzo; de Luna, Mark D. G.; Ballesteros, Florencio C.

    2016-01-01

    This paper provides a critical review about the integration of electrochemical processes into membrane bioreactors (MBR) in order to understand the influence of these processes on wastewater treatment performance and membrane fouling control. The integration can be realized either in an internal or an external configuration. Electrically enhanced membrane bioreactors or electro membrane bioreactors (eMBRs) combine biodegradation, electrochemical and membrane filtration processes into one syst...

  5. Combination of electrochemical processes with membrane bioreactors for wastewater treatment and fouling control: A review

    OpenAIRE

    Benny Marie B. Ensano; Laura Borea; Vincenzo Naddeo; Vincenzo Belgiorno; Mark Daniel G. de Luna; Mark Daniel G. de Luna; Florencio C. Ballesteros, Jr.; Florencio C. Ballesteros, Jr.

    2016-01-01

    This paper provides a critical review about the integration of electrochemical processes into membrane bioreactors (MBR) in order to understand the influence of these processes on wastewater treatment performance and membrane fouling control. The integration can be realized either in an internal or an external configuration. Electrically enhanced membrane bioreactors or electro membrane bioreactors (eMBRs) combine biodegradation, electrochemical and membrane filtration processes into one syst...

  6. Membrane tension regulates clathrin-coated pit dynamics

    Science.gov (United States)

    Liu, Allen

    2014-03-01

    Intracellular organization depends on close communication between the extracellular environment and a network of cytoskeleton filaments. The interactions between cytoskeletal filaments and the plasma membrane lead to changes in membrane tension that in turns help regulate biological processes. Endocytosis is thought to be stimulated by low membrane tension and the removal of membrane increases membrane tension. While it is appreciated that the opposing effects of exocytosis and endocytosis have on keeping plasma membrane tension to a set point, it is not clear how membrane tension affects the dynamics of clathrin-coated pits (CCPs), the individual functional units of clathrin-mediated endocytosis. Furthermore, although it was recently shown that actin dynamics counteracts membrane tension during CCP formation, it is not clear what roles plasma membrane tension plays during CCP initiation. Based on the notion that plasma membrane tension is increased when the membrane area increases during cell spreading, we designed micro-patterned surfaces of different sizes to control the cell spreading sizes. Total internal reflection fluorescence microscopy of living cells and high content image analysis were used to quantify the dynamics of CCPs. We found that there is an increased proportion of CCPs with short (<20s) lifetime for cells on larger patterns. Interestingly, cells on larger patterns have higher CCP initiation density, an effect unexpected based on the conventional view of decreasing endocytosis with increasing membrane tension. Furthermore, by analyzing the intensity profiles of CCPs that were longer-lived, we found CCP intensity decreases with increasing cell size, indicating that the CCPs are smaller with increasing membrane tension. Finally, disruption of actin dynamics significantly increased the number of short-lived CCPs, but also decreased CCP initiation rate. Together, our study reveals new mechanistic insights into how plasma membrane tension regulates

  7. Nanofiltration and nanostructured membranes--should they be considered nanotechnology or not?

    Science.gov (United States)

    Mueller, Nicole C; van der Bruggen, Bart; Keuter, Volkmar; Luis, Patricia; Melin, Thomas; Pronk, Wouter; Reisewitz, Robert; Rickerby, David; Rios, Gilbert M; Wennekes, Wilco; Nowack, Bernd

    2012-04-15

    Nanofiltration is frequently associated with nanotechnology - obviously because of its name. However, the term "nano" in nanofiltration refers - according to the definition of the International Union of Pure and Applied Chemistry (IUPAC) - to the size of the particles rejected and not to a nanostructure as defined by the International Organisation of Standardisation (ISO) in the membrane. Evidently, the approach to standardisation of materials differs significantly between membrane technology and nanotechnology which leads to considerable confusion and inconsistent use of the terminology. There are membranes that can be unambiguously attributed to both membrane technology and nanotechnology such as those that are functionalized with nanoparticles, while the classification of hitherto considered to be conventional membranes as nanostructured material is questionable. A driving force behind the efforts to define nanomaterials is not least the urgent need for the regulation of the use of nanomaterials. Since risk estimation is the basis for nanotechnology legislation, the risk associated with nanomaterials should also be reflected in the underlying standards and definitions. This paper discusses the impacts of the recent attempts to define nanomaterials on membrane terminology in the light of risk estimations and the need for regulation. Copyright © 2011 Elsevier B.V. All rights reserved.

  8. Membrane raft association is a determinant of plasma membrane localization.

    Science.gov (United States)

    Diaz-Rohrer, Blanca B; Levental, Kandice R; Simons, Kai; Levental, Ilya

    2014-06-10

    The lipid raft hypothesis proposes lateral domains driven by preferential interactions between sterols, sphingolipids, and specific proteins as a central mechanism for the regulation of membrane structure and function; however, experimental limitations in defining raft composition and properties have prevented unequivocal demonstration of their functional relevance. Here, we establish a quantitative, functional relationship between raft association and subcellular protein sorting. By systematic mutation of the transmembrane and juxtamembrane domains of a model transmembrane protein, linker for activation of T-cells (LAT), we generated a panel of variants possessing a range of raft affinities. These mutations revealed palmitoylation, transmembrane domain length, and transmembrane sequence to be critical determinants of membrane raft association. Moreover, plasma membrane (PM) localization was strictly dependent on raft partitioning across the entire panel of unrelated mutants, suggesting that raft association is necessary and sufficient for PM sorting of LAT. Abrogation of raft partitioning led to mistargeting to late endosomes/lysosomes because of a failure to recycle from early endosomes. These findings identify structural determinants of raft association and validate lipid-driven domain formation as a mechanism for endosomal protein sorting.

  9. Control of membrane fouling during hyperhaline municipal wastewater treatment using a pilot-scale anoxic/aerobic-membrane bioreactor system

    Institute of Scientific and Technical Information of China (English)

    Jingmei Sun; Jiangxiu Rong; Lifeng Dai; Baoshan Liu; Wenting Zhu

    2011-01-01

    Membrane fouling limits the effects of long-term stable operation of membrane bioreactor (MBR).Control of membrane foulin can extend the membrane life and reduce water treatment cost effectively.A pilot scale anoxic/aerobic-membrane bioreactor (A/O MBR,40 L/hr) was used to treat the hyperhaline municipal sewage from a processing zone of Tianjin,China.Impact factors including mixed liquid sludge suspension (MLSS),sludge viscosity (μ),microorganisms,extracellular polymeric substances (EPS),aeration intensity and suction/suspended time on membrane fouling and pollution control were studied.The relationships among various factors associated with membrane fouling were analyzed.Results showed that there was a positive correlation among MLSS,sludge viscosity and trans-membrane pressure (TMP).Considering water treatment efficiency and stable operation of the membrane module,MLSS of 5 g/L was suggested for the process.There was a same trend among EPS,sludge viscosity and TMP.Numbers and species of microorganisms affected membrane fouling.Either too high or too low aeration intensity was not conducive to membrane fouling control.Aeration intensity of 1.0 m3/hr (gas/water ratio of 25:1) is suggested for the process.A long suction time caused a rapid increase in membrane resistance.However,long suspended time cannot prevent the increase of membrane resistance effectively even though a suspended time was necessary for scale off particles from the membrane surface.The suction/suspended time of 12 min/3 min was selected for the process.The interaction of various environmental factors and operation conditions must be considered synthetically.

  10. Synthetic membrane-targeted antibiotics.

    Science.gov (United States)

    Vooturi, S K; Firestine, S M

    2010-01-01

    Antimicrobial resistance continues to evolve and presents serious challenges in the therapy of both nosocomial and community-acquired infections. The rise of resistant strains like methicillin-resistant Staphylococcus aureus (MRSA), vancomycin-resistant Staphylococcus aureus (VRSA) and vancomycin-resistant enterococci (VRE) suggests that antimicrobial resistance is an inevitable evolutionary response to antimicrobial use. This highlights the tremendous need for antibiotics against new bacterial targets. Agents that target the integrity of bacterial membrane are relatively novel in the clinical armamentarium. Daptomycin, a lipopeptide is a classical example of membrane-bound antibiotic. Nature has also utilized this tactic. Antimicrobial peptides (AMPs), which are found in all kingdoms, function primarily by permeabilizing the bacterial membrane. AMPs have several advantages over existing antibiotics including a broad spectrum of activity, rapid bactericidal activity, no cross-resistance with the existing antibiotics and a low probability for developing resistance. Currently, a small number of peptides have been developed for clinical use but therapeutic applications are limited because of poor bioavailability and high manufacturing cost. However, their broad specificity, potent activity and lower probability for resistance have spurred the search for synthetic mimetics of antimicrobial peptides as membrane-active antibiotics. In this review, we will discuss the different classes of synthetic membrane-bound antibiotics published since 2004.

  11. Tunable-Porosity Membranes From Discrete Nanoparticles

    Science.gov (United States)

    Marchetti, Patrizia; Mechelhoff, Martin; Livingston, Andrew G.

    2015-01-01

    Thin film composite membranes were prepared through a facile single-step wire-wound rod coating procedure in which internally crosslinked poly(styrene-co-butadiene) polymer nanoparticles self-assembled to form a thin film on a hydrophilic ultrafiltration support. This nanoparticle film provided a defect-free separation layer 130–150 nm thick, which was highly permeable and able to withstand aggressive pH conditions beyond the range of available commercial membranes. The nanoparticles were found to coalesce to form a rubbery film when heated above their glass transition temperature (Tg). The retention properties of the novel membrane were strongly affected by charge repulsion, due to the negative charge of the hydroxyl functionalized nanoparticles. Porosity was tuned by annealing the membranes at different temperatures, below and above the nanoparticle Tg. This enabled fabrication of membranes with varying performance. Nanofiltration properties were achieved with a molecular weight cut-off below 500 g mol−1 and a low fouling tendency. Interestingly, after annealing above Tg, memory of the interstitial spaces between the nanoparticles persisted. This memory led to significant water permeance, in marked contrast to the almost impermeable films cast from a solution of the same polymer. PMID:26626565

  12. High yield cell-free production of integral membrane proteins without refolding or detergents.

    Science.gov (United States)

    Wuu, Jessica J; Swartz, James R

    2008-05-01

    Integral membrane proteins act as critical cellular components and are important drug targets. However, difficulties in producing membrane proteins have hampered investigations of structure and function. In vivo production systems are often limited by cell toxicity, and previous in vitro approaches have required unnatural folding pathways using detergents or lipid solutions. To overcome these limitations, we present an improved cell-free expression system which produces high yields of integral membrane proteins without the use of detergents or refolding steps. Our cell-free reaction activates an Escherichia coli-derived cell extract for transcription and translation. Purified E. coli inner membrane vesicles supply membrane-bound components and the lipid environment required for insertion and folding. Using this system, we demonstrated successful synthesis of two complex integral membrane transporters, the tetracycline pump (TetA) and mannitol permease (MtlA), in yields of 570+/-50 microg/mL and 130+/-30 microg/mL of vesicle-associated protein, respectively. These yields are up to 400 times typical in vivo concentrations. Insertion and folding of these proteins are verified by sucrose flotation, protease digestion, and activity assays. Whereas TetA incorporates efficiently into vesicle membranes with over two-thirds of the synthesized protein being inserted, MtlA yields appear to be limited by insufficient concentrations of a membrane-associated chaperone.

  13. Identification of membrane proteins by tandem mass spectrometry of protein ions

    Science.gov (United States)

    Carroll, Joe; Altman, Matthew C.; Fearnley, Ian M.; Walker, John E.

    2007-01-01

    The most common way of identifying proteins in proteomic analyses is to use short segments of sequence (“tags”) determined by mass spectrometric analysis of proteolytic fragments. The approach is effective with globular proteins and with membrane proteins with significant polar segments between membrane-spanning α-helices, but it is ineffective with other hydrophobic proteins where protease cleavage sites are either infrequent or absent. By developing methods to purify hydrophobic proteins in organic solvents and by fragmenting ions of these proteins by collision induced dissociation with argon, we have shown that partial sequences of many membrane proteins can be deduced easily by manual inspection. The spectra from small proteolipids (1–4 transmembrane α-helices) are dominated usually by fragment ions arising from internal amide cleavages, from which internal sequences can be obtained, whereas the spectra from larger membrane proteins (5–18 transmembrane α-helices) often contain fragment ions from N- and/or C-terminal parts yielding sequences in those regions. With these techniques, we have, for example, identified an abundant protein of unknown function from inner membranes of mitochondria that to our knowledge has escaped detection in proteomic studies, and we have produced sequences from 10 of 13 proteins encoded in mitochondrial DNA. They include the ND6 subunit of complex I, the last of its 45 subunits to be analyzed. The procedures have the potential to be developed further, for example by using newly introduced methods for protein ion dissociation to induce fragmentation of internal regions of large membrane proteins, which may remain partially folded in the gas phase. PMID:17720804

  14. Long-Time Plasma Membrane Imaging Based on a Two-Step Synergistic Cell Surface Modification Strategy.

    Science.gov (United States)

    Jia, Hao-Ran; Wang, Hong-Yin; Yu, Zhi-Wu; Chen, Zhan; Wu, Fu-Gen

    2016-03-16

    Long-time stable plasma membrane imaging is difficult due to the fast cellular internalization of fluorescent dyes and the quick detachment of the dyes from the membrane. In this study, we developed a two-step synergistic cell surface modification and labeling strategy to realize long-time plasma membrane imaging. Initially, a multisite plasma membrane anchoring reagent, glycol chitosan-10% PEG2000 cholesterol-10% biotin (abbreviated as "GC-Chol-Biotin"), was incubated with cells to modify the plasma membranes with biotin groups with the assistance of the membrane anchoring ability of cholesterol moieties. Fluorescein isothiocyanate (FITC)-conjugated avidin was then introduced to achieve the fluorescence-labeled plasma membranes based on the supramolecular recognition between biotin and avidin. This strategy achieved stable plasma membrane imaging for up to 8 h without substantial internalization of the dyes, and avoided the quick fluorescence loss caused by the detachment of dyes from plasma membranes. We have also demonstrated that the imaging performance of our staining strategy far surpassed that of current commercial plasma membrane imaging reagents such as DiD and CellMask. Furthermore, the photodynamic damage of plasma membranes caused by a photosensitizer, Chlorin e6 (Ce6), was tracked in real time for 5 h during continuous laser irradiation. Plasma membrane behaviors including cell shrinkage, membrane blebbing, and plasma membrane vesiculation could be dynamically recorded. Therefore, the imaging strategy developed in this work may provide a novel platform to investigate plasma membrane behaviors over a relatively long time period.

  15. Membrane-based technologies for biogas separations.

    Science.gov (United States)

    Basu, Subhankar; Khan, Asim L; Cano-Odena, Angels; Liu, Chunqing; Vankelecom, Ivo F J

    2010-02-01

    Over the past two decades, membrane processes have gained a lot of attention for the separation of gases. They have been found to be very suitable for wide scale applications owing to their reasonable cost, good selectivity and easily engineered modules. This critical review primarily focuses on the various aspects of membrane processes related to the separation of biogas, more in specific CO(2) and H(2)S removal from CH(4) and H(2) streams. Considering the limitations of inorganic materials for membranes, the present review will only focus on work done with polymeric materials. An overview on the performance of commercial membranes and lab-made membranes highlighting the problems associated with their applications will be given first. The development studies carried out to enhance the performance of membranes for gas separation will be discussed in the subsequent section. This review has been broadly divided into three sections (i) performance of commercial polymeric membranes (ii) performance of lab-made polymeric membranes and (iii) performance of mixed matrix membranes (MMMs) for gas separations. It will include structural modifications at polymer level, polymer blending, as well as synthesis of mixed matrix membranes, for which addition of silane-coupling agents and selection of suitable fillers will receive special attention. Apart from an overview of the different membrane materials, the study will also highlight the effects of different operating conditions that eventually decide the performance and longevity of membrane applications in gas separations. The discussion will be largely restricted to the studies carried out on polyimide (PI), cellulose acetate (CA), polysulfone (PSf) and polydimethyl siloxane (PDMS) membranes, as these membrane materials have been most widely used for commercial applications. Finally, the most important strategies that would ensure new commercial applications will be discussed (156 references).

  16. Membrane reactor technology for ultrapure hydrogen production

    NARCIS (Netherlands)

    Patil, Charudatta Subhash

    2005-01-01

    The suitability of polymer electrolyte membrane fuel cells (PEMFC) for stationary and vehicular applications because of its low operating temperatures, compactness, higher power density, cleaner exhausts and higher efficiencies compared to conventional internal combustion engines and gas turbines

  17. Modified polyether-sulfone membrane: a mini review.

    Science.gov (United States)

    Alenazi, Noof A; Hussein, Mahmoud A; Alamry, Khalid A; Asiri, Abdullah M

    2017-01-01

    Polyethersulfone has been widely used as a promising material in medical applications and waste-treatment membranes since it provides excellent mechanical and thermal properties. Hydrophobicity of polyethersulfone is considered one main disadvantage of using this material because hydrophobic surface causes biofouling effects to the membrane which is always thought to be a serious limitation to the use of polyethersulfone in membrane technology. Chemical modification to the material is a promising solution to this problem. More specifically surface modification is an excellent technique to introduce hydrophilic properties and functional groups to the polyethersulfone membrane surface. This review covers chemical modifications of the polyethersulfone and covers different methods used to enhance the hydrophilicity of polyethersulfone membrane. In particular, the addition of amino functional groups to polyethersulfone is used as a fundamental method either to introduce hydrophilic properties or introduce nanomaterials to the surface of polyethersulfone membrane. This work reviews also previous research reports explored the use of amino functionalized polyethersulfone with different nanomaterials to induce biological activity and reduce fouling effects of the fabricated membrane.

  18. Evaluation of the international limitations and conditions of the Argentinian nuclear politics

    International Nuclear Information System (INIS)

    Martin, Hugo R.

    2003-01-01

    It is a broadly accepted fact that the Argentine Republic is one of the few development countries that has reached an advance status in the world in pacific applications of nuclear science and technology. A retrospective vision of the main technical and political aspects that characterized the process to global scale allows to confirm, starting from the theory of the International Relations, that the position reached by the country was the consequence of a coherent effort sustained under the almost exclusive conduction of the National Atomic Energy Commission (CNEA). The Nuclear politics of Argentine in the international concert during the last fifty years, sample a behavior of non adhesion to the juridical treaties commitments that were considered limitative for the initial objectives proposed when President General J. D. Peron created the CNEA in 1950: self-sufficiency and national autonomy. This continuity shows an unusual coherence in the foreign policy of the country maintained by all the governments that exercised the power during five decades. The result of this investigation task has allowed to elaborate a complex, reasonably coherent vision of the consequences that the limitations and conditions on the Argentine nuclear politics had in the three temporary dimensions and in different levels. From the theoretical point of view, the scenario starts from the crisis of the Utopism that revaluate the Classic Realism (H. Morgenthau) after the Second World War. In the next stage K. Waltz's Structural Realism starts when the internationalization process of the nuclear technology begins in the 50. Other theoretical models: Complex Interdependence (R. Keohane and J. Nye) and Peripheric Realism (C. Escude) at local level seem to be the representative models to describe the Argentine political behavior in the nuclear politic and to prove that the main variable in this field was the genuine domain of the scientific and technological knowledge developed in the national

  19. Internal cycling, not external loading, decides the nutrient limitation in eutrophic lake: A dynamic model with temporal Bayesian hierarchical inference.

    Science.gov (United States)

    Wu, Zhen; Liu, Yong; Liang, Zhongyao; Wu, Sifeng; Guo, Huaicheng

    2017-06-01

    Lake eutrophication is associated with excessive anthropogenic nutrients (mainly nitrogen (N) and phosphorus (P)) and unobserved internal nutrient cycling. Despite the advances in understanding the role of external loadings, the contribution of internal nutrient cycling is still an open question. A dynamic mass-balance model was developed to simulate and measure the contributions of internal cycling and external loading. It was based on the temporal Bayesian Hierarchical Framework (BHM), where we explored the seasonal patterns in the dynamics of nutrient cycling processes and the limitation of N and P on phytoplankton growth in hyper-eutrophic Lake Dianchi, China. The dynamic patterns of the five state variables (Chla, TP, ammonia, nitrate and organic N) were simulated based on the model. Five parameters (algae growth rate, sediment exchange rate of N and P, nitrification rate and denitrification rate) were estimated based on BHM. The model provided a good fit to observations. Our model results highlighted the role of internal cycling of N and P in Lake Dianchi. The internal cycling processes contributed more than external loading to the N and P changes in the water column. Further insights into the nutrient limitation analysis indicated that the sediment exchange of P determined the P limitation. Allowing for the contribution of denitrification to N removal, N was the more limiting nutrient in most of the time, however, P was the more important nutrient for eutrophication management. For Lake Dianchi, it would not be possible to recover solely by reducing the external watershed nutrient load; the mechanisms of internal cycling should also be considered as an approach to inhibit the release of sediments and to enhance denitrification. Copyright © 2017 Elsevier Ltd. All rights reserved.

  20. 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.

  1. Polymer-metal organic frameworks (MOFs) mixed matrix membranes for gas separation applications

    NARCIS (Netherlands)

    Shahid, S.

    2015-01-01

    The performance of polymeric membranes is often limited by a trade-off between membrane permeability and selectivity, the so-called Robeson upper bound. Additionally, in high pressure CO2 capture applications, excessive swelling of the polymer membrane often leads to plasticization resulting in

  2. Carbon nanotube embedded PVDF membranes: Effect of solvent composition on the structural morphology for membrane distillation

    Science.gov (United States)

    Mapunda, Edgar C.; Mamba, Bhekie B.; Msagati, Titus A. M.

    2017-08-01

    Rapid population increase, growth in industrial and agricultural sectors and global climate change have added significant pressure on conventional freshwater resources. Tapping freshwater from non-conventional water sources such as desalination and wastewater recycling is considered as sustainable alternative to the fundamental challenges of water scarcity. However, affordable and sustainable technologies need to be applied for the communities to benefit from the treatment of non-conventional water source. Membrane distillation is a potential desalination technology which can be used sustainably for this purpose. In this work multi-walled carbon nanotube embedded polyvinylidene fluoride membranes for application in membrane distillation desalination were prepared via non-solvent induced phase separation method. The casting solution was prepared using mixed solvents (N, N-dimethylacetamide and triethyl phosphate) at varying ratios to study the effect of solvent composition on membrane morphological structures. Membrane morphological features were studied using a number of techniques including scanning electron microscope, atomic force microscope, SAXSpace tensile strength analysis, membrane thickness, porosity and contact angle measurements. It was revealed that membrane hydrophobicity, thickness, tensile strength and surface roughness were increasing as the composition of N, N-dimethylacetamide in the solvent was increasing with maximum values obtained between 40 and 60% N, N-dimethylacetamide. Internal morphological structures were changing from cellular structures to short finger-like and sponge-like pores and finally to large macro void type of pores when the amount of N, N-dimethylacetamide in the solvent was changed from low to high respectively. Multi-walled carbon nanotube embedded polyvinylidene fluoride membranes of desired morphological structures and physical properties can be synthesized by regulating the composition of solvents used to prepare the

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

    KAUST Repository

    Hunt, Anton; Dimitrakopoulos, Georgios; Ghoniem, Ahmed F.

    2015-01-01

    © 2015 Elsevier B.V. The mechanisms and quantitative models for how oxygen is separated from air using ion transport membranes (ITMs) are not well understood, largely due to the experimental complexity for determining surface exchange reactions

  4. A membrane paradigm at large D

    Energy Technology Data Exchange (ETDEWEB)

    Bhattacharyya, Sayantani [Department of Physics, Indian Institute of Technology Kanpur,Kanpur 208016 (India); De, Anandita [Department of Physics, Indian Institute of Science Education and Research,Dr. Homi Bhabha Road, Pune 411008 (India); Minwalla, Shiraz; Mohan, Ravi; Saha, Arunabha [Department of Theoretical Physics, Tata Institute of Fundamental Research,Homi Bhabha Road, Mumbai 400005 (India)

    2016-04-13

    We study SO(d+1) invariant solutions of the classical vacuum Einstein equations in p+d+3 dimensions. In the limit d→∞ with p held fixed we construct a class of solutions labelled by the shape of a membrane (the event horizon), together with a ‘velocity’ field that lives on this membrane. We demonstrate that our metrics can be corrected to nonsingular solutions at first sub-leading order in (1/d) if and only if the membrane shape and ‘velocity’ field obey equations of motion which we determine. These equations define a well posed initial value problem for the membrane shape and this ‘velocity’ and so completely determine the dynamics of the black hole. They may be viewed as governing the non-linear dynamics of the light quasi normal modes of Emparan, Suzuki and Tanabe.

  5. Processing of membranes for oxygenation using the Bellhouse-effect

    Directory of Open Access Journals (Sweden)

    Neußer C.

    2015-09-01

    Full Text Available State-of-the-art lung support systems are limited to short time application because of a lack of long term hemocompatibility and protein absorption on the membrane surfaces. In a highly interdisciplinary project at RWTH Aachen University a biohybrid lung assist system with endothelialised gas exchange flat membranes is developed to improve long term compatibility of oxygenators. To increase the gas exchange performance of flat membranes hollows are imprinted in the membrane surfaces. This approach is based on the research of B. J. Bell-house et al. [1], who discovered this effect, now known as Bellhouse-effect, around 1960. In this paper a processes to manufacture membrane assemblies for oxygenation with imprinted hollows on the flat membrane surfaces is reviewed.

  6. The internal disruption as hard Magnetohydrodynamic limit of 1/2 sawtooth like activity in large helical device

    Energy Technology Data Exchange (ETDEWEB)

    Varela, J. [Department of Physics, Universidad Carlos III, 28911 Leganes, Madrid (Spain); Watanabe, K. Y.; Ohdachi, S. [National Institute for Fusion Science, Oroshi-cho 322-6, Toki 509-5292 (Japan)

    2012-08-15

    Large helical device (LHD) inward-shifted configurations are unstable to resistive MHD pressure-gradient-driven modes. Sawtooth like activity was observed during LHD operation. The main drivers are the unstable modes 1/2 and 1/3 in the middle and inner plasma region which limit the plasma confinement efficiency of LHD advanced operation scenarios. The aim of the present research is to study the hard MHD limit of 1/2 sawtooth like activity, not observed yet in LHD operation, and to predict its effects on the device performance. Previous investigations pointed out this system relaxation can be an internal disruption [J. Varela et al., 'Internal disruptions and sawtooth like activity in LHD,' 38th EPS Conference on Plasma Physics (2011), P5.077]. In the present work, we simulate an internal disruption; we study the equilibria properties before and after the disruptive process, its effects on the plasma confinement efficiency during each disruptive phase, the relation between the n/m = 1/2 hard MHD events and the soft MHD events, and how to avoid or reduce their adverse effects. The simulation conclusions point out that the large stochastic region in the middle plasma strongly deforms and tears the flux surfaces when the pressure gradient increases above the hard MHD limit. If the instability reaches the inner plasma, the iota profiles will be perturbed near the plasma core and three magnetic islands can appear near the magnetic axis. If the instability is strong enough to link the stochastic regions in the middle plasma (around the half minor radius {rho}) and the plasma core ({rho}<0.25), an internal disruption is driven.

  7. Housekeeping genes as internal standards: use and limits.

    Science.gov (United States)

    Thellin, O; Zorzi, W; Lakaye, B; De Borman, B; Coumans, B; Hennen, G; Grisar, T; Igout, A; Heinen, E

    1999-10-08

    Quantitative studies are commonly realised in the biomedical research to compare RNA expression in different experimental or clinical conditions. These quantifications are performed through their comparison to the expression of the housekeeping gene transcripts like glyceraldehyde-3-phosphate dehydrogenase (G3PDH), albumin, actins, tubulins, cyclophilin, hypoxantine phsophoribosyltransferase (HRPT), L32. 28S, and 18S rRNAs are also used as internal standards. In this paper, it is recalled that the commonly used internal standards can quantitatively vary in response to various factors. Possible variations are illustrated using three experimental examples. Preferred types of internal standards are then proposed for each of these samples and thereafter the general procedure concerning the choice of an internal standard and the way to manage its uses are discussed.

  8. Gyroid Membranes made from Nanoporous Blck Copolymers

    DEFF Research Database (Denmark)

    Szewczykowski, Piotr Plzemystaw; Vigild, Martin Etchells; Ndoni, Sokol

    2007-01-01

    are used to characterize the morphology, find the pore diameter, pore size distribution and internal surface area (Small Angle X-Scattering, Scanning Electron Microscopy, Transmission Electron Microscopy and Nitrogen Adsorption). The performance of these gyroid membranes is evaluated by investigating gas...

  9. A membrane stirrer for product recovery and substrate feeding.

    Science.gov (United States)

    Femmer, T; Carstensen, F; Wessling, M

    2015-02-01

    During fermentation processes, in situ product recovery (ISPR) using submerged membranes allows a continuous operation mode with effective product removal. Continuous recovery reduces product inhibition and organisms in the reactor are not exposed to changing reaction conditions. For an effective in situ product removal, submerged membrane systems should have a sufficient large membrane area and an anti-fouling concept integrated in a compact device for the limited space in a lab-scale bioreactor. We present a new membrane stirrer with integrated filtration membranes on the impeller blades as well as an integrated gassing concept in an all-in-one device. The stirrer is fabricated by rapid prototyping and is equipped with a commercial micromesh membrane. Filtration performance is tested using a yeast cell suspension with different stirring speeds and aeration fluxes. We reduce membrane fouling by backflushing through the membrane with the product stream. © 2014 Wiley Periodicals, Inc.

  10. 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.

  11. Catalytic membrane in reduction of aqueous nitrates: operational principles and catalytic performance

    NARCIS (Netherlands)

    Ilinitch, O.M.; Cuperus, F.P.; Nosova, L.V.; Gribov, E.N.

    2000-01-01

    The catalytic membrane with palladium-copper active component supported over the macroporous ceramic membrane, and a series of γ-Al 2O 3 supported Pd-Cu catalysts were prepared and investigated. In reduction of nitrate ions by hydrogen in water at ambient temperature, pronounced internal diffusion

  12. Spin chain from membrane and the Neumann-Rosochatius integrable system

    International Nuclear Information System (INIS)

    Bozhilov, P.

    2007-01-01

    We find membrane configurations in AdS 4 xS 7 , which correspond to the continuous limit of the SU(2) integrable spin chain, considered as a limit of the SU(3) spin chain, arising in N=4 SYM in four dimensions, dual to strings in AdS 5 xS 5 . We also discuss the relationship with the Neumann-Rosochatius integrable system at the level of Lagrangians, comparing the string and membrane cases

  13. Global Proteomic Analysis Reveals an Exclusive Role of Thylakoid Membranes in Bioenergetics of a Model Cyanobacterium

    Energy Technology Data Exchange (ETDEWEB)

    Liberton, Michelle; Saha, Rajib; Jacobs, Jon M.; Nguyen, Amelia Y.; Gritsenko, Marina A.; Smith, Richard D.; Koppenaal, David W.; Pakrasi, Himadri B.

    2016-04-07

    Cyanobacteria are photosynthetic microbes with highly differentiated membrane systems. These organisms contain an outer membrane, plasma membrane, and an internal system of thylakoid membranes where the photosynthetic and respiratory machinery are found. This existence of compartmentalization and differentiation of membrane systems poses a number of challenges for cyanobacterial cells in terms of organization and distribution of proteins to the correct membrane system. Proteomics studies have long sought to identify the components of the different membrane systems, and to date about 450 different proteins have been attributed to either the plasma membrane or thylakoid membrane. Given the complexity of these membranes, many more proteins remain to be identified in these membrane systems, and a comprehensive catalog of plasma membrane and thylakoid membrane proteins is needed. Here we describe the identification of 635 proteins in Synechocystis sp. PCC 6803 by quantitative iTRAQ isobaric labeling; of these, 459 proteins were localized to the plasma membrane and 176 were localized to the thylakoid membrane. Surprisingly, we found over 2.5 times the number of unique proteins identified in the plasma membrane compared to the thylakoid membrane. This suggests that the protein composition of the thylakoid membrane is more homogeneous than the plasma membrane, consistent with the role of the plasma membrane in diverse cellular processes including protein trafficking and nutrient import, compared to a more specialized role for the thylakoid membrane in cellular energetics. Overall, the protein composition of the Synechocystis 6803 plasma membrane and thylakoid membrane is quite similar to the E.coli plasma membrane and Arabidopsis thylakoid membrane, respectively. Synechocystis 6803 can therefore be described as a gram-negative bacterium that has an additional internal membrane system that fulfils the energetic requirements of the cell.

  14. Global Proteomic Analysis Reveals an Exclusive Role of Thylakoid Membranes in Bioenergetics of a Model Cyanobacterium

    Energy Technology Data Exchange (ETDEWEB)

    Liberton, Michelle; Saha, Rajib; Jacobs, Jon M.; Nguyen, Amelia Y.; Gritsenko, Marina A.; Smith, Richard D.; Koppenaal, David W.; Pakrasi, Himadri B.

    2016-04-07

    Cyanobacteria are photosynthetic microbes with highlydifferentiated membrane systems. These organisms contain an outer membrane, plasma membrane, and an internal system of thylakoid membranes where the photosynthetic and respiratory machinery are found. This existence of compartmentalization and differentiation of membrane systems poses a number of challenges for cyanobacterial cells in terms of organization and distribution of proteins to the correct membrane system. Proteomics studies have long sought to identify the components of the different membrane systems in cyanobacteria, and to date about 450 different proteins have been attributed to either the plasma membrane or thylakoid membrane. Given the complexity of these membranes, many more proteins remain to be identified, and a comprehensive catalogue of plasma membrane and thylakoid membrane proteins is needed. Here we describe the identification of 635 differentially localized proteins in Synechocystis sp. PCC 6803 by quantitative iTRAQ isobaric labeling; of these, 459 proteins were localized to the plasma membrane and 176 were localized to the thylakoid membrane. Surprisingly, we found over 2.5 times the number of unique proteins identified in the plasma membrane compared with the thylakoid membrane. This suggests that the protein composition of the thylakoid membrane is more homogeneous than the plasma membrane, consistent with the role of the plasma membrane in diverse cellular processes including protein trafficking and nutrient import, compared with a more specialized role for the thylakoid membrane in cellular energetics. Thus, our data clearly define the two membrane systems with distinct functions. Overall, the protein compositions of the Synechocystis 6803 plasma membrane and thylakoid membrane are quite similar to that of the plasma membrane of Escherichia coli and thylakoid membrane of Arabidopsis chloroplasts, respectively. Synechocystis 6803 can therefore be described as a Gram

  15. Assessing the removal of organic micro-pollutants from anaerobic membrane bioreactor effluent by fertilizer-drawn forward osmosis

    KAUST Repository

    Kim, Youngjin

    2017-03-23

    In this study, the behavior of organic micro-pollutants (OMPs) transport including membrane fouling was assessed in fertilizer-drawn forward osmosis (FDFO) during treatment of the anaerobic membrane bioreactor (AnMBR) effluent. The flux decline was negligible when the FO membrane was oriented with active layer facing feed solution (AL-FS) while severe flux decline was observed with active layer facing draw solution (AL-DS) with di-ammonium phosphate (DAP) fertilizer as DS due to struvite scaling inside the membrane support layer. DAP DS however exhibited the lowest OMPs forward flux or higher OMPs rejection rate compared to other two fertilizers (i.e., mono-ammonium phosphate (MAP) and KCl). MAP and KCl fertilizer DS had higher water fluxes that induced higher external concentration polarization (ECP) and enhanced OMPs flux through the FO membrane. Under the AL-DS mode of membrane orientation, OMPs transport was further increased with MAP and KCl as DS due to enhanced concentrative internal concentration polarization while with DAP the internal scaling enhanced mass transfer resistance thereby lowering OMPs flux. Physical or hydraulic cleaning could successfully recover water flux for FO membranes operated under the AL-FS mode but only partial flux recovery was observed for membranes operated under AL-DS mode because of internal scaling and fouling in the support layer. Osmotic backwashing could however significantly improve the cleaning efficiency.

  16. Progress of Nanocomposite Membranes for Water Treatment

    Directory of Open Access Journals (Sweden)

    Claudia Ursino

    2018-04-01

    Full Text Available The use of membrane-based technologies has been applied for water treatment applications; however, the limitations of conventional polymeric membranes have led to the addition of inorganic fillers to enhance their performance. In recent years, nanocomposite membranes have greatly attracted the attention of scientists for water treatment applications such as wastewater treatment, water purification, removal of microorganisms, chemical compounds, heavy metals, etc. The incorporation of different nanofillers, such as carbon nanotubes, zinc oxide, graphene oxide, silver and copper nanoparticles, titanium dioxide, 2D materials, and some other novel nano-scale materials into polymeric membranes have provided great advances, e.g., enhancing on hydrophilicity, suppressing the accumulation of pollutants and foulants, enhancing rejection efficiencies and improving mechanical properties and thermal stabilities. Thereby, the aim of this work is to provide up-to-date information related to those novel nanocomposite membranes and their contribution for water treatment applications.

  17. Progress of Nanocomposite Membranes for Water Treatment.

    Science.gov (United States)

    Ursino, Claudia; Castro-Muñoz, Roberto; Drioli, Enrico; Gzara, Lassaad; Albeirutty, Mohammad H; Figoli, Alberto

    2018-04-03

    The use of membrane-based technologies has been applied for water treatment applications; however, the limitations of conventional polymeric membranes have led to the addition of inorganic fillers to enhance their performance. In recent years, nanocomposite membranes have greatly attracted the attention of scientists for water treatment applications such as wastewater treatment, water purification, removal of microorganisms, chemical compounds, heavy metals, etc. The incorporation of different nanofillers, such as carbon nanotubes, zinc oxide, graphene oxide, silver and copper nanoparticles, titanium dioxide, 2D materials, and some other novel nano-scale materials into polymeric membranes have provided great advances, e.g., enhancing on hydrophilicity, suppressing the accumulation of pollutants and foulants, enhancing rejection efficiencies and improving mechanical properties and thermal stabilities. Thereby, the aim of this work is to provide up-to-date information related to those novel nanocomposite membranes and their contribution for water treatment applications.

  18. Neonatal and pediatric extracorporeal membrane oxygenation in developing Latin American countries

    OpenAIRE

    Kattan, Javier; González, Álvaro; Castillo, Andrés; Caneo, Luiz Fernando

    2017-01-01

    Objective: To review the principles of neonatal‐pediatric extracorporeal membrane oxygenation therapy, prognosis, and its establishment in limited resource‐limited countries in Latino America. Sources: The PubMed database was explored from 1985 up to the present, selecting from highly‐indexed and leading Latin American journals, and Extracorporeal Life Support Organization reports. Summary of the findings: Extracorporeal membrane oxygenation provides “time” for pulmonary and cardiac res...

  19. Characterization of Bifunctional Spin Labels for Investigating the Structural and Dynamic Properties of Membrane Proteins Using EPR Spectroscopy.

    Science.gov (United States)

    Sahu, Indra D; Craig, Andrew F; Dunagum, Megan M; McCarrick, Robert M; Lorigan, Gary A

    2017-10-05

    Site-directed spin labeling (SDSL) coupled with electron paramagnetic resonance (EPR) spectroscopy is a very powerful technique to study structural and dynamic properties of membrane proteins. The most widely used spin label is methanthiosulfonate (MTSL). However, the flexibility of this spin label introduces greater uncertainties in EPR measurements obtained for determining structures, side-chain dynamics, and backbone motion of membrane protein systems. Recently, a newer bifunctional spin label (BSL), 3,4-bis(methanethiosulfonylmethyl)-2,2,5,5-tetramethyl-2,5-dihydro-1H-pyrrol-1-yloxy, has been introduced to overcome the dynamic limitations associated with the MTSL spin label and has been invaluable in determining protein backbone dynamics and inter-residue distances due to its restricted internal motion and fewer size restrictions. While BSL has been successful in providing more accurate information about the structure and dynamics of several proteins, a detailed characterization of the spin label is still lacking. In this study, we characterized BSLs by performing CW-EPR spectral line shape analysis as a function of temperature on spin-labeled sites inside and outside of the membrane for the integral membrane protein KCNE1 in POPC/POPG lipid bilayers and POPC/POPG lipodisq nanoparticles. The experimental data revealed a powder pattern spectral line shape for all of the KCNE1-BSL samples at 296 K, suggesting the motion of BSLs approaches the rigid limit regime for these series of samples. BSLs were further utilized to report for the first time the distance measurement between two BSLs attached on an integral membrane protein KCNE1 in POPC/POPG lipid bilayers at room temperature using dipolar line broadening CW-EPR spectroscopy. The CW dipolar line broadening EPR data revealed a 15 ± 2 Å distance between doubly attached BSLs on KCNE1 (53/57-63/67) which is consistent with molecular dynamics modeling and the solution NMR structure of KCNE1 which yielded a

  20. Microfluidic platform for efficient Nanodisc assembly, membrane protein incorporation, and purification.

    Science.gov (United States)

    Wade, James H; Jones, Joshua D; Lenov, Ivan L; Riordan, Colleen M; Sligar, Stephen G; Bailey, Ryan C

    2017-08-22

    The characterization of integral membrane proteins presents numerous analytical challenges on account of their poor activity under non-native conditions, limited solubility in aqueous solutions, and low expression in most cell culture systems. Nanodiscs are synthetic model membrane constructs that offer many advantages for studying membrane protein function by offering a native-like phospholipid bilayer environment. The successful incorporation of membrane proteins within Nanodiscs requires experimental optimization of conditions. Standard protocols for Nanodisc formation can require large amounts of time and input material, limiting the facile screening of formation conditions. Capitalizing on the miniaturization and efficient mass transport inherent to microfluidics, we have developed a microfluidic platform for efficient Nanodisc assembly and purification, and demonstrated the ability to incorporate functional membrane proteins into the resulting Nanodiscs. In addition to working with reduced sample volumes, this platform simplifies membrane protein incorporation from a multi-stage protocol requiring several hours or days into a single platform that outputs purified Nanodiscs in less than one hour. To demonstrate the utility of this platform, we incorporated Cytochrome P450 into Nanodiscs of variable size and lipid composition, and present spectroscopic evidence for the functional active site of the membrane protein. This platform is a promising new tool for membrane protein biology and biochemistry that enables tremendous versatility for optimizing the incorporation of membrane proteins using microfluidic gradients to screen across diverse formation conditions.

  1. Wetting Resistance of Commercial Membrane Distillation Membranes in Waste Streams Containing Surfactants and Oil

    Directory of Open Access Journals (Sweden)

    Lies Eykens

    2017-01-01

    Full Text Available Water management is becoming increasingly challenging and several technologies, including membrane distillation (MD are emerging. This technology is less affected by salinity compared to reverse osmosis and is able to treat brines up to saturation. The focus of MD research recently shifted from seawater desalination to industrial applications out of the scope of reverse osmosis. In many of these applications, surfactants or oil traces are present in the feed stream, lowering the surface tension and increasing the risk for membrane wetting. In this study, the technological boundaries of MD in the presence of surfactants are investigated using surface tension, contact angle and liquid entry pressure measurements together with lab-scale MD experiments to predict the wetting resistance of different membranes. Synthetic NaCl solutions mixed with sodium dodecyl sulfate (SDS were used as feed solution. The limiting surfactant concentration was found to be dependent on the surface chemistry of the membrane, and increased with increasing hydrophobicity and oleophobicity. Additionally, a hexadecane/SDS emulsion was prepared with a composition simulating produced water, a waste stream in the oil and gas sector. When hexadecane is present in the emulsion, oleophobic membranes are able to resist wetting, whereas polytetrafluoretheen (PTFE is gradually wetted by the feed liquid.

  2. The plasma membrane proteome of germinating barley embryos

    DEFF Research Database (Denmark)

    Hynek, Radovan; Svensson, Birte; Jensen, O.N.

    2009-01-01

    Cereal seed germination involves a complex coordination between different seed tissues. Plasma membranes must play crucial roles in coordination and execution of germination; however, very little is known about seed plasma membrane proteomes due to limited tissue amounts combined...... with amphiphilicity and low abundance of membrane proteins. A fraction enriched in plasma membranes was prepared from embryos dissected from 18 h germinated barley seeds using aqueous two-phase partitioning. Reversed-phase chromatography on C-4 resin performed in micro-spin columns with stepwise elution by 2-propanol...... was used to reduce soluble protein contamination and enrich for hydrophobic proteins. Sixty-one proteins in 14 SDS-PAGE bands were identified by LC-MS/MS and database searches. The identifications provide new insight into the plasma membrane functions in seed germination....

  3. Importance of balancing membrane and electrode water in anion exchange membrane fuel cells

    Science.gov (United States)

    Omasta, T. J.; Wang, L.; Peng, X.; Lewis, C. A.; Varcoe, J. R.; Mustain, W. E.

    2018-01-01

    Anion exchange membrane fuel cells (AEMFCs) offer several potential advantages over proton exchange membrane fuel cells (PEMFCs), most notably to overcome the cost barrier that has slowed the growth and large scale implementation of fuel cells for transportation. However, limitations in performance have held back AEMFCs, specifically in the areas of stability, carbonation, and maximum achievable current and power densities. In order for AEMFCs to contend with PEMFCs for market viability, it is necessary to realize a competitive cell performance. This work demonstrates a new benchmark for a H2/O2 AEMFC with a peak power density of 1.4 W cm-2 at 60 °C. This was accomplished by taking a more precise look at balancing necessary membrane hydration while preventing electrode flooding, which somewhat surprisingly can occur both at the anode and the cathode. Specifically, radiation-grafted ETFE-based anion exchange membranes and anion exchange ionomer powder, functionalized with benchmark benzyltrimethylammonium groups, were utilized to examine the effects of the following parameters on AEMFC performance: feed gas flow rate, the use of hydrophobic vs. hydrophilic gas diffusion layers, and gas feed dew points.

  4. NMR structural studies of peptides and proteins in membranes

    Energy Technology Data Exchange (ETDEWEB)

    Opella, S J [Pennsylvania Univ., Philadelphia, PA (United States). Dept. of Chemistry

    1994-12-31

    The use of NMR methodology in structural studies is described as applicable to larger proteins, considering that the majority of membrane proteins is constructed from a limited repertoire of structural and dynamic elements. The membrane associated domains of these proteins are made up of long hydrophobic membrane spanning helices, shorter amphipathic bridging helices in the plane of the bilayer, connecting loops with varying degrees of mobility, and mobile N- and C- terminal sections. NMR studies have been successful in identifying all of these elements and their orientations relative to each other and the membrane bilayer 19 refs., 9 figs.

  5. Mercury Concentration Reduction In Waste Water By Using Liquid Surfactant Membrane Technique

    International Nuclear Information System (INIS)

    Prayitno; Sardjono, Joko

    2000-01-01

    The objective of this research is ti know effectiveness of liquid surfactant membrane in diminishing mercury found in waste water. This process can be regarded as transferring process of solved mercury from the external phase functioning as a moving phase to continue to the membrane internal one. The existence of the convection rotation results in the change of the surface pressure on the whole interface parts, so the solved mercury disperses on every interface part. Because of this rotation, the solved mercury will fulfil every space with particles from dispersion phase in accordance with its volume. Therefore, the change of the surface pressure on the whole interface parts can be kept stable to adsorb mercury. The mercury adsorbed in the internal phase moves to dispersed particles through molecule diffusion process. The liquid surfactant membrane technique in which the membrane phase is realized into emulsion contains os kerosene as solvent, sorbitan monoleat (span-80) 5 % (v/v) as surfactant, threbuthyl phosphate (TBP) 10 % (v/v) as extractant, and solved mercury as the internal phase. All of those things are mixed and stirred with 8000 rpm speed for 20 minutes. After the stability of emulsion is formed, the solved mercury is extracted by applying extraction process. The effective condition required to achieve mercury ion recovery utilizing this technique is obtained through extraction and re-extraction process. This process was conducted in 30 minutes with membrane and mercury in scale 1 : 1 on 100 ppm concentration. The results of the processes was 99,6 % efficiency. This high efficiency shows that the liquid surfactant membrane technique is very effective to reduce waste water contamined by mercury

  6. Modeling the ion transfer and polarization of ion exchange membranes in bioelectrochemical systems.

    Science.gov (United States)

    Harnisch, Falk; Warmbier, Robert; Schneider, Ralf; Schröder, Uwe

    2009-06-01

    An explicit numerical model for the charge balancing ion transfer across monopolar ion exchange membranes under conditions of bioelectrochemical systems is presented. Diffusion and migration equations have been solved according to the Nernst-Planck Equation and the resulting ion concentrations, pH values and the resistance values of the membrane for different conditions were computed. The modeling results underline the principle limitations of the application of ion exchange membranes in biological fuel cells and electrolyzers, caused by the inherent occurrence of a pH-gradient between anode and cathode compartment, and an increased ohmic membrane resistance at decreasing electrolyte concentrations. Finally, the physical and numerical limitations of the model are discussed.

  7. Sustainability of thermoplastic vinyl roofing membrane systems

    Energy Technology Data Exchange (ETDEWEB)

    Graveline, S. P. [Sika Sanarfil, Canton, (United States)

    2010-07-01

    The International Council for Research and Innovation in Building and Construction (CIB-RILEM) has developed a framework for sustainable roofing based on a series of tenets divided into three key areas: preservation of the environment, conservation of energy, and extended roof life. This paper investigated the sustainability of thermoplastic vinyl roof membranes using these guidelines and the relevant tenets for roof system selection. Several tenets provided alternatives for minimizing the burden on the environment using non-renewable raw materials, conserving energy with thermal insulation, and extending the lifespan of all roof components by using long lasting membranes. A life cycle assessment was carried out to provide a quantitative framework for assessing the sustainability of roofing materials. It was found that the PVC membrane systems had a lesser impact on the environment than other competing systems.

  8. Major Intrinsic Proteins in Biomimetic Membranes

    DEFF Research Database (Denmark)

    Helix Nielsen, Claus

    2010-01-01

    or as sensor devices based on e.g., the selective permeation of metalloids. In principle a MIP based membrane sensor/separation device requires the supporting biomimetic matrix to be virtually impermeable to anything but water or the solute in question. In practice, however, a biomimetic support matrix....../separation technology, a unique class of membrane transport proteins is especially interesting the major intrinsic proteins (MIPs). Generally, MIPs conduct water molecules and selected solutes in and out of the cell while preventing the passage of other solutes, a property critical for the conservation of the cells...... internal pH and salt concentration. Also known as water channels or aquaporins they are highly efficient membrane pore proteins some of which are capable of transporting water at very high rates up to 109 molecules per second. Some MIPs transport other small, uncharged solutes, such as glycerol and other...

  9. Outer membrane vesicles from Brucella abortus promote bacterial internalization by human monocytes and modulate their innate immune response.

    Directory of Open Access Journals (Sweden)

    Cora N Pollak

    Full Text Available Outer membrane vesicles (OMVs released by some gram-negative bacteria have been shown to exert immunomodulatory effects that favor the establishment of the infection. The aim of the present study was to assess the interaction of OMVs from Brucella abortus with human epithelial cells (HeLa and monocytes (THP-1, and the potential immunomodulatory effects they may exert. Using confocal microscopy and flow cytometry, FITC-labeled OMVs were shown to be internalized by both cell types. Internalization was shown to be partially mediated by clathrin-mediated endocytosis. Pretreatment of THP-1 cells with Brucella OMVs inhibited some cytokine responses (TNF-α and IL-8 to E. coli LPS, Pam3Cys or flagellin (TLR4, TLR2 and TLR5 agonists, respectively. Similarly, pretreatment with Brucella OMVs inhibited the cytokine response of THP-1 cells to B. abortus infection. Treatment of THP-1 cells with OMVs during IFN-γ stimulation reduced significantly the inducing effect of this cytokine on MHC-II expression. OMVs induced a dose-dependent increase of ICAM-1 expression on THP-1 cells and an increased adhesion of these cells to human endothelial cells. The addition of OMVs to THP-1 cultures before the incubation with live B. abortus resulted in increased numbers of adhered and internalized bacteria as compared to cells not treated with OMVs. Overall, these results suggest that OMVs from B. abortus exert cellular effects that promote the internalization of these bacteria by human monocytes, but also downregulate the innate immune response of these cells to Brucella infection. These effects may favor the persistence of Brucella within host cells.

  10. Development of an Internal Real-Time Wireless Diagnostic Tool for a Proton Exchange Membrane Fuel Cell.

    Science.gov (United States)

    Lee, Chi-Yuan; Chen, Chia-Hung; Tsai, Chao-Hsuan; Wang, Yu-Syuan

    2018-01-13

    To prolong the operating time of unmanned aerial vehicles which use proton exchange membrane fuel cells (PEMFC), the performance of PEMFC is the key. However, a long-term operation can make the Pt particles of the catalyst layer and the pollutants in the feedstock gas bond together (e.g., CO), so that the catalyst loses reaction activity. The performance decay and aging of PEMFC will be influenced by operating conditions, temperature, flow and CO concentration. Therefore, this study proposes the development of an internal real-time wireless diagnostic tool for PEMFC, and uses micro-electro-mechanical systems (MEMS) technology to develop a wireless and thin (PEMFC; (5) customized design and development. The flexible integrated microsensor is embedded in the PEMFC, three important physical quantities in the PEMFC, which are the temperature, flow and CO, can be measured simultaneously and instantly, so as to obtain the authentic and complete reaction in the PEMFC to enhance the performance of PEMFC and to prolong the service life.

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

    Directory of Open Access Journals (Sweden)

    Liane Brescovici Nunes

    2014-03-01

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

  12. Wastewater treatment with ion-exchange chitin membrane

    International Nuclear Information System (INIS)

    Paulenova, A.; Fjeld, R. A.; Visacky, V.

    2001-01-01

    Chitin, poly(N-acetyl-D glucosamine) and chitosan, its deacetylated derivates have recently obtained attention as bio-sorbents, because they shown a great ability to accumulate heavy metals and other pollutants. It was found that recovery of metals is strongly affected by pH. At low acidic pH range 4-5 chitin membrane exhibits better selectivity for lead than for cadmium or zinc. Sorption preference for metals decreases in the order: Pb > Cd > Zn. For uranium, as well for strontium was observed significant increase of recovery at decrease of pH to slightly acidic, close to neutral value. It was shown that chemical behavior of chitin membrane is excellent; ion-exchange nature of chitin was not changed during chitin membrane manufacturing process. Using of chitin membrane instead of chitin flake column brings significant increasing of driving force of the separation process, limited in the case of column experimental design by diffusion coefficient, while in the case of membrane process only by mass transfer coefficient. (authors)

  13. Water flow prediction for Membranes using 3D simulations with detailed morphology

    KAUST Repository

    Shi, Meixia

    2015-04-01

    The membrane morphology significantly influences membrane performance. For osmotically driven membrane processes, the morphology strongly affects the internal concentration polarization. Different membrane morphologies were generated by simulation and their influence on membrane performance was studied, using a 3D model. The simulation results were experimentally validated for two classical phase-inversion membrane morphologies: sponge- and finger-like structures. Membrane porosity and scanning electron microscopy image information were used as model input. The permeance results from the simulation fit well the experimentally measured permeances. Water permeances were predicted for different kinds of finger-like cavity membranes with different finger-like cavity lengths and various finger-like cavity sets, as well as for membranes with cylindrical cavities. The results provide realistic information on how to increase water permeance, and also illustrate that membrane’s complete morphology is important for the accurate water permeance evaluation. Evaluations only based on porosity might be misleading, and the new 3D simulation approach gives a more realistic representation.

  14. Water flow prediction for Membranes using 3D simulations with detailed morphology

    KAUST Repository

    Shi, Meixia; Printsypar, Galina; Iliev, Oleg; Calo, Victor M.; Amy, Gary L.; Nunes, Suzana Pereira

    2015-01-01

    The membrane morphology significantly influences membrane performance. For osmotically driven membrane processes, the morphology strongly affects the internal concentration polarization. Different membrane morphologies were generated by simulation and their influence on membrane performance was studied, using a 3D model. The simulation results were experimentally validated for two classical phase-inversion membrane morphologies: sponge- and finger-like structures. Membrane porosity and scanning electron microscopy image information were used as model input. The permeance results from the simulation fit well the experimentally measured permeances. Water permeances were predicted for different kinds of finger-like cavity membranes with different finger-like cavity lengths and various finger-like cavity sets, as well as for membranes with cylindrical cavities. The results provide realistic information on how to increase water permeance, and also illustrate that membrane’s complete morphology is important for the accurate water permeance evaluation. Evaluations only based on porosity might be misleading, and the new 3D simulation approach gives a more realistic representation.

  15. A membrane wave equation for Q.C.D. (SU(infinity))

    International Nuclear Information System (INIS)

    Botelho, L.C.L.

    1988-01-01

    It is proposed a quantum membrane wave functional describing the interaction between a colored SU(N c ) membrane and a quantized Yang-Mills field. Additionally, its associated wave equation in the t'Hooft N c ->infinity limit is deduced. (A.C.A.S.) [pt

  16. Membranes, methods of making membranes, and methods of separating gases using membranes

    Science.gov (United States)

    Ho, W. S. Winston

    2012-10-02

    Membranes, methods of making membranes, and methods of separating gases using membranes are provided. The membranes can include at least one hydrophilic polymer, at least one cross-linking agent, at least one base, and at least one amino compound. The methods of separating gases using membranes can include contacting a gas stream containing at least one of CO.sub.2, H.sub.2S, and HCl with one side of a nonporous and at least one of CO.sub.2, H.sub.2S, and HCl selectively permeable membrane such that at least one of CO.sub.2, H.sub.2S, and HCl is selectively transported through the membrane.

  17. Ultramicroelectrode studies of oxygen reduction in polyelectrolyte membranes

    Energy Technology Data Exchange (ETDEWEB)

    Holdcroft, S.; Abdou, M.S.; Beattie, P.; Basura, V. [Simon Fraser Univ., Burnaby, BC (Canada). Dept. of Chemistry

    1997-12-31

    A study on the oxygen reduction reaction in a solid state electrochemical cell was presented. The oxygen reduction reaction is a rate limiting reaction in the operation of solid polymer electrolyte fuel cells which use H{sub 2} and O{sub 2}. Interest in the oxygen reduction reaction of platinum electrodes in contact with Nafion electrolytes stems from its role in fuel cell technology. The kinetics of the oxygen reduction reaction in different polyelectrolyte membranes, such as Nafion and non-Nafion membranes, were compared. The electrode kinetics and mass transport parameters of the oxygen reduction reaction in polyelectrolyte membranes were measured by ultramicroelectrode techniques. The major difference found between these two classes of membrane was the percentage of water, which is suggestive of superior electrochemical mass transport properties of the non-Nafion membranes. 2 refs. 1 fig.

  18. Dense ceramic membranes based on ion conducting oxides

    International Nuclear Information System (INIS)

    Fontaine, M.L.; Larring, Y.; Bredesen, R.; Norby, T.; Grande, T.

    2007-01-01

    This chapter reviews the recent progress made in the fields of high temperature oxygen and hydrogen separation membranes. Studies of membranes for oxygen separation are mainly focusing on materials design to improve flux, and to lesser extent, related to stability issues. High oxygen fluxes satisfying industrial requirements can be obtained but, for many materials, the surface exchange rate is limiting the performance. The current status on electrolyte-type and mixed proton and electron conducting membranes is outlined, highlighting materials with improved stability in typical applications as solid oxide fuel cell technology and gas separation. In our presentation more fundamental aspects related to transport properties, chemical and mechanical stability of membrane materials are also treated. It is concluded that a significantly better understanding of the long term effects of operation in chemical gradients is needed for these types of membrane materials. (authors)

  19. Nanocomposites for Improved Physical Durability of Porous PVDF Membranes

    Science.gov (United States)

    Lai, Chi Yan; Groth, Andrew; Gray, Stephen; Duke, Mikel

    2014-01-01

    Current commercial polymer membranes have shown high performance and durability in water treatment, converting poor quality waters to higher quality suitable for drinking, agriculture and recycling. However, to extend the treatment into more challenging water sources containing abrasive particles, micro and ultrafiltration membranes with enhanced physical durability are highly desirable. This review summarises the current limits of the existing polymeric membranes to treat harsh water sources, followed by the development of nanocomposite poly(vinylidene fluoride) (PVDF) membranes for improved physical durability. Various types of nanofillers including nanoparticles, carbon nanotubes (CNT) and nanoclays were evaluated for their effect on flux, fouling resistance, mechanical strength and abrasion resistance on PVDF membranes. The mechanisms of abrasive wear and how the more durable materials provide resistance was also explored. PMID:24957121

  20. Super-resolution optical microscopy for studying membrane structure and dynamics.

    Science.gov (United States)

    Sezgin, Erdinc

    2017-07-12

    Investigation of cell membrane structure and dynamics requires high spatial and temporal resolution. The spatial resolution of conventional light microscopy is limited due to the diffraction of light. However, recent developments in microscopy enabled us to access the nano-scale regime spatially, thus to elucidate the nanoscopic structures in the cellular membranes. In this review, we will explain the resolution limit, address the working principles of the most commonly used super-resolution microscopy techniques and summarise their recent applications in the biomembrane field.

  1. Characterization of membrane foulants at ambient temperature anaerobic membrane bioreactor treating low-strength industrial wastewater

    DEFF Research Database (Denmark)

    Zarebska, Agata; Kjerstadius, Hamse; Petrinic, Irena

    2016-01-01

    The large volume of industrial low-strength wastewaters has a potential for biogas production through conventional anaerobic digestion (AD), limited though by the need of heating and concentrating of the wastewaters. The use of anaerobic membrane bioreactor (AnMBR) combining membrane filtration...... with anaerobic biological treatment at low temperature could not only reduce the operational cost of AD, but also alleviate environmental problems. However, at low temperature the AnMBR may suffer more fouling due to the increased extracellular polymeric substances production excreted by bacteria hampering...... the application of the process for the industrial wastewater treatment. In order to solve or reduce the fouling problem it is necessary to have a good insight into the processes that take place both on and in the membrane pores during filtration. Therefore, the objective of this study is to contribute to a better...

  2. Forward osmosis biomimetic membranes in industrial and environmental applications

    DEFF Research Database (Denmark)

    Madsen, Henrik Tækker; Søgaard, Erik Gydesen; Bajraktari, Niada

    Membrane processes have in recent years found increasing uses in several sectors where separation of one or more components from a solvent, typically water, is required. The most widespread types of membranes are polymeric and pressure driven, but the high pressures that are required results...... consumption and lead to much more stable operations, but is currently limited by the availability of suitable membranes. However, by introducing aquaporin protein channels into a polymeric membrane to make a biomimetic membrane, the vision of both high flux and separation efficiency may be achieved......) a single use filtration module containing a sample reservoir and a biomimetic aquaporin based forward osmosis membrane. 2) a multi-use desktop forward osmosis system containing draw solution mixing, and monitoring devices. The sample is placed in the single use module and the module is then mounted...

  3. Silver and gold nanoparticle coated membranes applied to protein dot blots

    International Nuclear Information System (INIS)

    Xie, F.; Drozdowicz-Tomsia, K.; Shtoyko, T.; Goldys, E. M.

    2011-01-01

    Detection and identification of low abundance biomarker proteins is frequently based on various types of membrane-based devices. Lowering of the protein detection limits is vital in commercial applications such as lateral flow assays and in Western blots widely used in proteomics. These currently suffer from insufficient detection sensitivity and low retention for small 2–5 kDa proteins. In this study, we report the deposition of two types of metal nanoparticles: gold colloids (50–95 nm diameter) and silver fractals onto a range of commonly used types of membranes including polyvinylidene fluoride (PVDF). Due to strong affinity of proteins to noble metals, such modified membranes have the potential to effectively capture trace proteins preventing their loss. The membranes modified by metal particles were characterized optically and by SEM. The membrane performance in protein dot blots was evaluated using the protein—fluorophore conjugates Deep Purple-bovine serum albumin and fluorescein—human serum albumin. We found that the metal nanoparticles increase light extinction by metals, which is balanced by increased fluorescence, so that the effective fluorescence signal is unchanged. This feature combined with the capture of proteins by the nanoparticles embedded in the membrane increases the detection limit of membrane assays.

  4. Osmotically-driven membrane processes for water reuse and energy recovery

    Science.gov (United States)

    Achilli, Andrea

    Osmotically-driven membrane processes are an emerging class of membrane separation processes that utilize concentrated brines to separate liquid streams. Their versatility of application make them an attractive alternative for water reuse and energy production/recovery. This work focused on innovative applications of osmotically-driven membrane processes. The novel osmotic membrane bioreactor (OMBR) system for water reuse was presented. Experimental results demonstrated high sustainable flux and relatively low reverse diffusion of solutes from the draw solution into the mixed liquor. Membrane fouling was minimal and controlled with osmotic backwashing. The OMBR system was found to remove greater than 99% of organic carbon and ammonium-nitrogen. Forward osmosis (FO) can employ different draw solution in its process. More than 500 inorganic compounds were screened as draw solution candidates, the desktop screening process resulted in 14 draw solutions suitable for FO applications. The 14 draw solutions were then tested in the laboratory to evaluate water flux and reverse salt diffusion through the membrane. Results indicated a wide range of water flux and reverse salt diffusion depending on the draw solution utilized. Internal concentration polarization was found to lower both water flux and reverse salt diffusion by reducing the draw solution concentration at the interface between the support and dense layer of the membrane. A small group of draw solutions was found to be most suitable for FO processes with currently available FO membranes. Another application of osmotically-driven membrane processes is pressure retarded osmosis (PRO). PRO was investigated as a viable source of renewable energy. A PRO model was developed to predict water flux and power density under specific experimental conditions. The predictive model was tested using experimental results from a bench-scale PRO system. Previous investigations of PRO were unable to verify model predictions due to

  5. Management and follow up of tibial plateau fractures by ′T′ clamp external fixator and limited internal fixation

    Directory of Open Access Journals (Sweden)

    Thimmegowda M

    2005-01-01

    Full Text Available Background: Tibial plateau fractures are difficult to treat especially when soft tissue is compromised by open reduction and internal fixation. Many methods have be1en tried in the past to manage these cases of which external fixation were shown to be effective as they limit the soft tissue and wound complications. Methods: Complex tibial plateau fractures of sixteen patients were treated by closed reduction, fixation of articular fragments by screws and application of unilateral external fixator. The external fixator was kept in place till fracture united clinically and radiologically. The patients were followed up for at least one year to assess the function of the knee joint Results: The average duration of external fixation was 13 weeks. All the fractures healed. Pin track infection (five patients and instability (six patients of the knee were encountered with this procedure. The average duration of follow up was 62 weeks. The mean range of motion was 1250 arc. The IOWA knee score averaged 90.3 points. Conclusions: External fixation with limited internal fixation may be effective in the management of complex tibial plateau fractures which requires further support from studies with large sample size. ′T′ clamp external fixation with limited Internal fixation is the procedure of choice when alignment, stability, early mobilisation is required in a soft tissue compromised tibial plateau fractures.

  6. Sphingolipid topology and the dynamic organization and function of membrane proteins.

    Science.gov (United States)

    van Meer, Gerrit; Hoetzl, Sandra

    2010-05-03

    When acquiring internal membranes and vesicular transport, eukaryotic cells started to synthesize sphingolipids and sterols. The physical differences between these and the glycerophospholipids must have enabled the cells to segregate lipids in the membrane plane. Localizing this event to the Golgi then allowed them to create membranes of different lipid composition, notably a thin, flexible ER membrane, consisting of glycerolipids, and a sturdy plasma membrane containing at least 50% sphingolipids and sterols. Besides sorting membrane proteins, in the course of evolution the simple sphingolipids obtained key positions in cellular physiology by developing specific interactions with (membrane) proteins involved in the execution and control of signaling. The few signaling sphingolipids in mammals must provide basic transmission principles that evolution has built upon for organizing the specific regulatory pathways tuned to the needs of the different cell types in the body. Copyright 2009 Federation of European Biochemical Societies. Published by Elsevier B.V. All rights reserved.

  7. Performance evaluation of an air-breathing high-temperature proton exchange membrane fuel cell

    International Nuclear Information System (INIS)

    Wu, Qixing; Li, Haiyang; Yuan, Wenxiang; Luo, Zhongkuan; Wang, Fang; Sun, Hongyuan; Zhao, Xuxin; Fu, Huide

    2015-01-01

    Highlights: • An air-breathing HT-PEMFC was designed and evaluated experimentally. • The peak power density of the air-breathing HT-PEMFC was 220.5 mW cm"−"2 at 200 °C. • Break-in behavior and effects of temperature and anodic stoichiometry were studied. • The effect of cell orientations on the performance was investigated. • The degradation rate of the air-breathing HT-PEMFC was around 58.32 μV h"−"1. - Abstract: The air-breathing proton exchange membrane fuel cell (PEMFC) is of great interest in mobile power sources because of its simple system design and low parasitic power consumption. Different from previous low-temperature air-breathing PEMFCs, a high-temperature PEMFC with a phosphoric acid doped polybenzimidazole (PBI) membrane as the polymer electrolyte is designed and investigated under air-breathing conditions. The preliminary results show that a peak power density of 220.5 mW cm"−"2 at 200 °C can be achieved without employing any water managements, which is comparable to those with conventional Nafion® membranes operated at low temperatures. In addition, it is found that with the present cell design, the limiting current density arising from the oxygen transfer limitation is around 700 mA cm"−"2 even at 200 °C. The short-term durability test at 200 mA cm"−"2 and 180 °C reveals that all the cells exhibit a gradual decrease in the voltage along with a rise in the internal resistance. The degradation rate of continuous operation is around 58.32 μV h"−"1, which is much smaller than those of start/stop cycling operations.

  8. Thin-Film Composite Pressure Retarded Osmosis Membranes for Sustainable Power Generation from Salinity Gradients

    KAUST Repository

    Yip, Ngai Yin

    2011-05-15

    Pressure retarded osmosis has the potential to produce renewable energy from natural salinity gradients. This work presents the fabrication of thin-film composite membranes customized for high performance in pressure retarded osmosis. We also present the development of a theoretical model to predict the water flux in pressure retarded osmosis, from which we can predict the power density that can be achieved by a membrane. The model is the first to incorporate external concentration polarization, a performance limiting phenomenon that becomes significant for high-performance membranes. The fabricated membranes consist of a selective polyamide layer formed by interfacial polymerization on top of a polysulfone support layer made by phase separation. The highly porous support layer (structural parameter S = 349 μm), which minimizes internal concentration polarization, allows the transport properties of the active layer to be customized to enhance PRO performance. It is shown that a hand-cast membrane that balances permeability and selectivity (A = 5.81 L m-2 h-1 bar-1, B = 0.88 L m-2 h-1) is projected to achieve the highest potential peak power density of 10.0 W/m2 for a river water feed solution and seawater draw solution. The outstanding performance of this membrane is attributed to the high water permeability of the active layer, coupled with a moderate salt permeability and the ability of the support layer to suppress the undesirable accumulation of leaked salt in the porous support. Membranes with greater selectivity (i.e., lower salt permeability, B = 0.16 L m-2 h-1) suffered from a lower water permeability (A = 1.74 L m-2 h-1 bar-1) and would yield a lower peak power density of 6.1 W/m2, while membranes with a higher permeability and lower selectivity (A = 7.55 L m-2 h-1 bar-1, B = 5.45 L m-2 h-1) performed poorly due to severe reverse salt permeation, resulting in a similar projected peak power density of 6.1 W/m2. © 2011 American Chemical Society.

  9. Molecular assemblies and membrane domains in multivesicular endosome dynamics

    International Nuclear Information System (INIS)

    Falguieres, Thomas; Luyet, Pierre-Philippe; Gruenberg, Jean

    2009-01-01

    Along the degradation pathway, endosomes exhibit a characteristic multivesicular organization, resulting from the budding of vesicles into the endosomal lumen. After endocytosis and transport to early endosomes, activated signaling receptors are incorporated into these intralumenal vesicles through the action of the ESCRT machinery, a process that contributes to terminate signaling. Then, the vesicles and their protein cargo are further transported towards lysosomes for degradation. Evidence also shows that intralumenal vesicles can undergo 'back-fusion' with the late endosome limiting membrane, a route exploited by some pathogens and presumably followed by proteins and lipids that need to be recycled from within the endosomal lumen. This process depends on the late endosomal lipid lysobisphosphatidic acid and its putative effector Alix/AIP1, and is presumably coupled to the invagination of the endosomal limiting membrane at the molecular level via ESCRT proteins. In this review, we discuss the intra-endosomal transport routes in mammalian cells, and in particular the different mechanisms involved in membrane invagination, vesicle formation and fusion in a space inaccessible to proteins known to control intracellular membrane traffic.

  10. 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

  11. Internal microdosimetry of inhaled radon progeny in bronchial airways: advantages and limitations

    International Nuclear Information System (INIS)

    Hofmann, Werner; Fakir, Hatim; Pihet, Pascal

    2007-01-01

    The objective of the present study was to identify advantages and limitations of the application of microdosimetric concepts for inhaled radon progeny activities in the lungs. The methods employed for this analysis were a recently developed Monte- Carlo microdosimetry code for the calculation of energy deposition in bronchial target cells and the Probability Per Unit Track Length (PPUTL) model, which relates these microdosimetric parameters to cellular radiation effects. The major advantages of internal microdosimetry of radon progeny in bronchial airways are: (i) quantitative characterisation of non-uniform dose distributions and identification of target sites with enhanced carcinogenic potential, (ii) quantification of low doses of alpha particles by the number of cells hit and the dose received by those cells, (iii) illustration of the random variations of cellular doses by specific energy distributions and (iv) establishment of a direct link to cellular radiobiological effects. At present, a major limitation of microdosimetry is the extrapolation of the response of individual cells to the resulting tissue response, which is still not fully explored. (authors)

  12. Principles of the International Commission on Radiological Protection system of dose limitation

    International Nuclear Information System (INIS)

    Thorne, M.C.

    1987-01-01

    The formulation of a quantitative system of dose limitation based on ICRP principles of 'stochastic' and 'non-stochastic' effects requires that judgements be made on several factors including: relationships between radiation dose and the induction of deleterious effects for a variety of endpoints and radiation types; acceptable levels of risk for radiation workers and members of the public; and methods of assessing whether the cost of introducing protective measures is justified by the reduction in radiation detriment which they will provide. In the case of patients deliberately exposed to ionising radiations, the objectives of radiation protection differ somewhat from those applying to radiation workers and members of the public. For patients, risks and benefits relate to the same person and upper limits on acceptable risks may differ grossly from those appropriate to normal individuals. For these reasons, and because of its historical relationship with the International Congress of Radiology, the ICRP has given special consideration to radiation protection in medicine and has published reports on protection of the patient in diagnostic radiology and in radiation therapy. (author)

  13. Novel determinants of H-Ras plasma membrane localization and transformation

    DEFF Research Database (Denmark)

    Willumsen, B M; Cox, A D; Solski, P A

    1996-01-01

    cysteine did not abolish palmitoylation. However, despite continued lipid modification the mutant proteins failed to bind to plasma membranes and instead accumulated on internal membranes and, importantly, were not transforming. Addition of an N-terminal myristoylation signal to these defective mutants......, or to proteins entirely lacking the C-terminal 25 residues restored both plasma membrane association and transforming activity. Thus, H-Ras does not absolutely require prenylation or palmitoylation nor indeed its hypervariable domain in order to interact with effectors that ultimately cause transformation....... However, in this native state, the C-terminus appears to provide a combination of lipids and a previously unrecognized signal for specific plasma membrane targeting that are essential for the correct localization and biological function of H-Ras....

  14. Bee venom phospholipase A2 as a membrane-binding vector for cell surface display or internalization of soluble proteins.

    Science.gov (United States)

    Babon, Aurélie; Wurceldorf, Thibault; Almunia, Christine; Pichard, Sylvain; Chenal, Alexandre; Buhot, Cécile; Beaumelle, Bruno; Gillet, Daniel

    2016-06-15

    We showed that bee venom phospholipase A2 can be used as a membrane-binding vector to anchor to the surface of cells a soluble protein fused to its C-terminus. ZZ, a two-domain derivative of staphylococcal protein A capable of binding constant regions of antibodies was fused to the C-terminus of the phospholipase or to a mutant devoid of enzymatic activity. The fusion proteins bound to the surface of cells and could themselves bind IgGs. Their fate depended on the cell type to which they bound. On the A431 carcinoma cell line the proteins remained exposed on the cell surface. In contrast, on human dendritic cells the proteins were internalized into early endosomes. Copyright © 2015 Elsevier Ltd. All rights reserved.

  15. Study on removal of cadmium from wastewater by emulsion liquid membrane

    International Nuclear Information System (INIS)

    Mortaheb, Hamid R.; Kosuge, Hitoshi; Mokhtarani, Babak; Amini, Mohammad H.; Banihashemi, Hamid R.

    2009-01-01

    Removal of cadmium from wastewater using emulsion liquid membrane (ELM) is studied in the present study. A polyamine-type surfactant was used for stabilizing the emulsion phase. Tri-iso-octyl amine (TIOA) has been used as a carrier for transferring of cadmium through the membrane. The results show good performance in the separation process. To determine the optimum operation conditions, the effect of several parameters such as surfactant concentration, carrier concentration, pH of external and internal phases, oil to internal phase volume ratio, emulsion to external phase volume ratio, solvent type, solute concentration, presence of iodide and chloride in external phase, and mixing conditions have been investigated.

  16. Optimization of a membrane reactor for hydrogen production with genetic algorithms

    International Nuclear Information System (INIS)

    Raceanu, Mircea; Iordache, Ioan; Curuia, Marian; Rasoi, Gabriel; Patularu, Laurentiu; Enache, Adrian

    2009-01-01

    Full text: Hydrogen is produced via steam reforming of hydrocarbons such as natural gas or methane by using conventional systems. Unfortunately, these systems need at least four different stages, consisting of three reactors and a purification system. Moreover, the steam reforming reaction is an endothermic thermodynamically limited system, meaning that high temperature energy supply is needed for complete conversion. Among different technologies related to production, separation and purification of H 2 , membrane technologies seem to really play a fundamental role. The specific thermodynamic limits are overcome using the so-called membrane reactors, systems in which both reaction and separation occur simultaneously. The hydrogen is driven across the membrane by the pressure difference, depending on the temperature, pressure and reactor length the methane can be completely converted and consequently very pure hydrogen is produced. A membrane reactor has two components which can be optimized namely, the membrane and the reactor dimensions. This paper presents a study on optimization of membrane reactor for enhancing the overall production. A mathematical heterogeneous model of the reactor was used for optimization of reactor performance. Genetic algorithms were used as powerful methods for optimization of complex problems. (authors)

  17. Giant Plasma Membrane Vesicles: An Experimental Tool for Probing the Effects of Drugs and Other Conditions on Membrane Domain Stability.

    Science.gov (United States)

    Gerstle, Zoe; Desai, Rohan; Veatch, Sarah L

    2018-01-01

    Giant plasma membrane vesicles (GPMVs) are isolated directly from living cells and provide an alternative to vesicles constructed of synthetic or purified lipids as an experimental model system for use in a wide range of assays. GPMVs capture much of the compositional protein and lipid complexity of intact cell plasma membranes, are filled with cytoplasm, and are free from contamination with membranes from internal organelles. GPMVs often exhibit a miscibility transition below the growth temperature of their parent cells. GPMVs labeled with a fluorescent protein or lipid analog appear uniform on the micron-scale when imaged above the miscibility transition temperature, and separate into coexisting liquid domains with differing membrane compositions and physical properties below this temperature. The presence of this miscibility transition in isolated GPMVs suggests that a similar phase-like heterogeneity occurs in intact plasma membranes under growth conditions, albeit on smaller length scales. In this context, GPMVs provide a simple and controlled experimental system to explore how drugs and other environmental conditions alter the composition and stability of phase-like domains in intact cell membranes. This chapter describes methods to generate and isolate GPMVs from adherent mammalian cells and to interrogate their miscibility transition temperatures using fluorescence microscopy. © 2018 Elsevier Inc. All rights reserved.

  18. Recycling Cellulase from Enzymatic Hydrolyzate of Laser-Pretreated Corn Stover by UF Membrane

    Directory of Open Access Journals (Sweden)

    Shuang-Qi Tian

    2015-09-01

    Full Text Available The ultrafiltration membrane reactor, utilizing a membrane module with a suitable molecular weight alleyway, retains the larger cellulase components. Smaller molecules, such as the fermentable reducing sugars and water, pass through the membrane. The purpose of this work was to investigate the capability of recycling cellulase in the UF membrane. PS30 hollow fiber membrane, an ultrafiltration method using internal pressure, was found to be an ideal membrane separation device, allowing re-use of the enzyme. A Box-Behnken experimental design (BBD established the following optimum pretreatment parameters: operation pressure at 1.73 bar, temperature at 36.38 °C, and a pH of 5.92. Under these conditions, the model predicted a membrane flux yield of 2.3174 L/(m2•h. The rejection rate of the UF membrane was over 95%.

  19. PAN-Immobilized PVC-NPOE Membrane for Environmentally Friendly Sensing of Cd(II Ions

    Directory of Open Access Journals (Sweden)

    Moersilah Moersilah

    2017-04-01

    Full Text Available A simple, cheap and environmentally friendly analytical method of Cd(II in the aqueous system has been developed by immobilization of 1-(2-pyridilazo-2-naphtol (PAN in poly vinyl chloride (PVC matrix and nitrophenyl octyl ether (NPOE as a plasticizer. Upon contact with Cd(II in solution, the color of sensor membrane changes from dark yellow to dark red, which is due to the formation of Cd(II–PAN complex. The best sensing results were obtained at pH 8.0 and λmax 558 nm. The dimension of the proposed sensor membrane was 0.8 cm x 2 cm with a thickness of 0.05 mm, the volume of sample was 2 mL with the Cd(II concentration range of  0 – 1.2 ppm. The limit of detection of the method was found to be 0.432 + 0.104 ppm, which was reversible. The proposed methods have been applied in the determination of Cd(II in water samples after addition of internal standard.

  20. 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

  1. Holographic QCD with topologically charged domain-wall/membranes

    International Nuclear Information System (INIS)

    Lin Fengli; Wu Shangyu

    2008-01-01

    We study the thermodynamical phase structures of holographic QCD with nontrivial topologically charged domain-wall/membranes which are originally related to the multiple θ-vacua in the large N c limit. We realize the topologically charged membranes as the holographic D6-brane fluxes in the Sakai-Sugimoto model. The D6-brane fluxes couple to the probe D8-D8-bar via Chern-Simon term, and act as the source for the baryonic current density of QCD. We find rich phase structures of the dual meson system by varying asymptotic separation of D8 and D8-bar. Especially, there can be a thermodynamically favored and stable phase of finite baryonic current density. This provides the supporting evidence for the discovery of the topologically charged membranes found in the lattice QCD calculations. We also find a crossover phase with the limiting baryonic current density and temperature which suggest a Hagedorn-like phase transition of meson dissociation.

  2. High-performance membrane-electrode assembly with an optimal polytetrafluoroethylene content for high-temperature polymer electrolyte membrane fuel cells

    DEFF Research Database (Denmark)

    Jeong, Gisu; Kim, MinJoong; Han, Junyoung

    2016-01-01

    Although high-temperature polymer electrolyte membrane fuel cells (HT-PEMFCs) have a high carbon monoxide tolerance and allow for efficient water management, their practical applications are limited due to their lower performance than conventional low-temperature PEMFCs. Herein, we present a high......-performance membrane-electrode assembly (MEA) with an optimal polytetrafluoroethylene (PTFE) content for HT-PEMFCs. Low or excess PTFE content in the electrode leads to an inefficient electrolyte distribution or severe catalyst agglomeration, respectively, which hinder the formation of triple phase boundaries...

  3. Prospects and problems of dense oxygen permeable membranes

    DEFF Research Database (Denmark)

    Hendriksen, P.V.; Larsen, P.H.; Mogensen, Mogens Bjerg

    2000-01-01

    The prospects of using mixed ionic/electronic conducting ceramics for syngas production in a catalytic membrane reactor are analysed. Problems relating to limited thermodynamic stability and poor dimensional stability of candidate materials are addressed, The consequences for these problems......, of flux improving measures like minimization of membrane thickness and minimization of the losses due to oxygen exchange over the membrane surfaces, are discussed. The analysis is conducted on two candidate materials: La0.6Sr0.4Co0.2Fe0.8O3-delta and SrFeCo0.5Ox. Finally. experimental investigations...

  4. Permeation of hydrogen through metal membranes

    International Nuclear Information System (INIS)

    Wienhold, P.; Rota, E.; Waelbroeck, F.; Winter, J.; Banno, Tatsuya.

    1986-08-01

    Experiments show that the permeant flux of hydrogen through a metal membrane at low driving pressures ( r is introduced into the model as a new material constant and the rate equations are given. After the description of the wall pump effect, a variety of different limiting cases are discussed for a symmetrical permeation membrane. This is modified to the asymmetric case and to the influence of particle implantation. The permeation number W turns out to be a dimensionless quantity which characterizes the permeation range and predicts the permeant flux in steady state. (orig.)

  5. pMD-Membrane: A Method for Ligand Binding Site Identification in Membrane-Bound Proteins.

    Directory of Open Access Journals (Sweden)

    Priyanka Prakash

    2015-10-01

    Full Text Available Probe-based or mixed solvent molecular dynamics simulation is a useful approach for the identification and characterization of druggable sites in drug targets. However, thus far the method has been applied only to soluble proteins. A major reason for this is the potential effect of the probe molecules on membrane structure. We have developed a technique to overcome this limitation that entails modification of force field parameters to reduce a few pairwise non-bonded interactions between selected atoms of the probe molecules and bilayer lipids. We used the resulting technique, termed pMD-membrane, to identify allosteric ligand binding sites on the G12D and G13D oncogenic mutants of the K-Ras protein bound to a negatively charged lipid bilayer. In addition, we show that differences in probe occupancy can be used to quantify changes in the accessibility of druggable sites due to conformational changes induced by membrane binding or mutation.

  6. Trace element analysis of water using radioisotope induced X-ray fluorescence (Cd-109) and a preconcentration-internal standard method

    International Nuclear Information System (INIS)

    Alvarez, M.; Cano, W.

    1986-10-01

    Radioisotope induced X-ray fluorescence using Cd-109 was used for the determination of iron, nickel, copper, zinc, lead and mercury in water. These metals were concentrated by precipitation with the chelating agent APDC. The precipitated formed was filtered using a membrane filter. Cobalt was added as an internal standard. Minimum detection limit, sensitivities and calibration curves linearities have been obtained to find the limits of the method. The usefulness of the method is illustrated analysing synthetic standard solutions. As an application analytical results are given for water of a highly polluted river area. (Author)

  7. Diffusive Silicon Nanopore Membranes for Hemodialysis Applications.

    Directory of Open Access Journals (Sweden)

    Steven Kim

    Full Text Available Hemodialysis using hollow-fiber membranes provides life-sustaining treatment for nearly 2 million patients worldwide with end stage renal disease (ESRD. However, patients on hemodialysis have worse long-term outcomes compared to kidney transplant or other chronic illnesses. Additionally, the underlying membrane technology of polymer hollow-fiber membranes has not fundamentally changed in over four decades. Therefore, we have proposed a fundamentally different approach using microelectromechanical systems (MEMS fabrication techniques to create thin-flat sheets of silicon-based membranes for implantable or portable hemodialysis applications. The silicon nanopore membranes (SNM have biomimetic slit-pore geometry and uniform pores size distribution that allow for exceptional permeability and selectivity. A quantitative diffusion model identified structural limits to diffusive solute transport and motivated a new microfabrication technique to create SNM with enhanced diffusive transport. We performed in vitro testing and extracorporeal testing in pigs on prototype membranes with an effective surface area of 2.52 cm2 and 2.02 cm2, respectively. The diffusive clearance was a two-fold improvement in with the new microfabrication technique and was consistent with our mathematical model. These results establish the feasibility of using SNM for hemodialysis applications with additional scale-up.

  8. Diffusive Silicon Nanopore Membranes for Hemodialysis Applications

    Science.gov (United States)

    Kim, Steven; Feinberg, Benjamin; Kant, Rishi; Chui, Benjamin; Goldman, Ken; Park, Jaehyun; Moses, Willieford; Blaha, Charles; Iqbal, Zohora; Chow, Clarence; Wright, Nathan; Fissell, William H.; Zydney, Andrew; Roy, Shuvo

    2016-01-01

    Hemodialysis using hollow-fiber membranes provides life-sustaining treatment for nearly 2 million patients worldwide with end stage renal disease (ESRD). However, patients on hemodialysis have worse long-term outcomes compared to kidney transplant or other chronic illnesses. Additionally, the underlying membrane technology of polymer hollow-fiber membranes has not fundamentally changed in over four decades. Therefore, we have proposed a fundamentally different approach using microelectromechanical systems (MEMS) fabrication techniques to create thin-flat sheets of silicon-based membranes for implantable or portable hemodialysis applications. The silicon nanopore membranes (SNM) have biomimetic slit-pore geometry and uniform pores size distribution that allow for exceptional permeability and selectivity. A quantitative diffusion model identified structural limits to diffusive solute transport and motivated a new microfabrication technique to create SNM with enhanced diffusive transport. We performed in vitro testing and extracorporeal testing in pigs on prototype membranes with an effective surface area of 2.52 cm2 and 2.02 cm2, respectively. The diffusive clearance was a two-fold improvement in with the new microfabrication technique and was consistent with our mathematical model. These results establish the feasibility of using SNM for hemodialysis applications with additional scale-up. PMID:27438878

  9. Studies of radiation induced membrane damage in lymphocytes using fluorescent probes

    International Nuclear Information System (INIS)

    Nikesch, W.

    1974-01-01

    The fluorescent probes perylene (PER), 1-anilino-8-naphthalene sulfonic acid (ANS), and fluorescein diacetate (FDA) were used to investigate membrane changes caused by ionizing radiation. Probe response to various other perturbations (variation of pH, temperature, and salt concentration, and treatment with phythohemagglutinin (PHA) and saponins) was also investigated to better understand membrane-probe interactions. ANS was used to probe the membrane surface, PER to probe the membrane interior, and FDA to investigate membrane integrity. Polarization of fluorescent light from ANS and PER was used to investigate the microviscosity and order of the membrane surface and interior respectively. Irradiated cells (600 R) were shown to have a decreased rate of hydrolysis of FDA probably due to cytoplasmic changes effecting the enzymatic reaction. Also evident was an increase in loss of intracellular fluorescein and a decrease in PER polarization indicating that the cells have a decreased membrane integrity, possibly the result of an increased disorganization of the phospholipid hydrocarbon chains in the membrane interior. Experiments with PHA link the decreased membrane integrity with the eventual interphase death of the cells. In general it is shown that the fluorescent probes ANS, PER, and FDA provide useful ways to investigate order and microviscosity in the cell membrane surface and interior, membrane surface charges, internal membrane polarity changes, and membrane integrity. (U.S.)

  10. Extraction of lithium ion from alkaline aqueous media by a liquid surfactant membrane

    International Nuclear Information System (INIS)

    Kinugasa, Takumi; Ono, Yuri; Kawamura, Yuko; Watanabe, Kunio; Takeuchi, Hiroshi.

    1995-01-01

    Extraction of lithium ion from aqueous alkaline media by a liquid surfactant membrane was performed using a mixture of LIX54 and TOPO as the extractant. Stripping of lithium from the kerosene solution to the acid solution was suppressed with increasing content of polyamine (ECA) surfactant. The extraction rate of lithium by the liquid membrane could be interpreted taking account of an interfacial resistance due to ECA. It was confirmed that swelling of the (W/O) emulsion drops by water permeation through the liquid membrane is evaluated in terms of a change in osmotic pressure gradient between the external and internal aqueous phases during the lithium extraction. In the present operation, the extraction ratio of Li + from the external feed and the uptake into the internal phase reached as high as 95%. (author)

  11. Proton exchange membrane water electrolysers

    International Nuclear Information System (INIS)

    Millet, P.

    2007-01-01

    This work deals with the PEM water electrolysis process. Are successively described: the thermodynamical, kinetic and energetic aspects, the different possible used electrolysis cells, the preparation of the membrane-electrode assembling, the used electrolysers, the annex production equipment, the uses fields and the limits of the process. (O.M.)

  12. Insertion of Neurotransmitters into a Lipid Bilayer Membrane and Its Implication on Membrane Stability: A Molecular Dynamics Study.

    Science.gov (United States)

    Shen, Chun; Xue, Minmin; Qiu, Hu; Guo, Wanlin

    2017-03-17

    The signaling molecules in neurons, called neurotransmitters, play an essential role in the transportation of neural signals, during which the neurotransmitters interact with not only specific receptors, but also cytomembranes, such as synaptic vesicle membranes and postsynaptic membranes. Through extensive molecular dynamics simulations, the atomic-scale insertion dynamics of typical neurotransmitters, including methionine enkephalin (ME), leucine enkephalin (LE), dopamine (DA), acetylcholine (ACh), and aspartic acid (ASP), into lipid bilayers is investigated. The results show that the first three neurotransmitters (ME, LE, and DA) are able to diffuse freely into both 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine (POPC) and 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphoethanolamine (POPE) membranes, and are guided by the aromatic residues Tyr and Phe. Only a limited number of these neurotransmitters are allowed to penetrate into the membrane, which suggests an intrinsic mechanism by which the membrane is protected from being destroyed by excessive inserted neurotransmitters. After spontaneous insertion, the neurotransmitters disturb the surrounding phospholipids in the membrane, as indicated by the altered distribution of components in lipid leaflets and the disordered lipid tails. In contrast, the last two neurotransmitters (ACh and ASP) cannot enter the membrane, but instead always diffuse freely in solution. These findings provide an understanding at the atomic level of how neurotransmitters interact with the surrounding cytomembrane, as well as their impact on membrane behavior. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  13. The influence of activation of heterogeneous ion-exchange membranes on their electrochemical properties

    Czech Academy of Sciences Publication Activity Database

    Brožová, Libuše; Křivčík, J.; Neděla, D.; Kysela, V.; Žitka, Jan

    2015-01-01

    Roč. 56, č. 12 (2015), s. 3228-3232 ISSN 1944-3994. [International Conference on Membrane and Electromembrane Processes - MELPRO 2014. Prague, 18.05.2014-21.05.2014] Institutional support: RVO:61389013 Keywords : heterogeneous ion-exchange membranes * electrochemical properties * activation Subject RIV: JP - Industrial Processing Impact factor: 1.272, year: 2015

  14. Partnerships – Limited partnerships and limited liability limited partnerships

    OpenAIRE

    Henning, Johan J.

    2000-01-01

    Consideration of the Limited Liability Partnership Act 2000 which introduced a new corporate entity, carrying the designations “partnership” and “limited” which allow members to limit their liability whilst organising themselves internally as a partnership. Article by Professor Johan Henning (Director of the Centre for Corporate Law and Practice, IALS and Dean of the Faculty of Law, University of the Free State, South Africa). Published in Amicus Curiae - Journal of the Institute of Advanced ...

  15. ENHANCEMENT OF EQUILIBRIUMSHIFT IN DEHYDROGENATION REACTIONS USING A NOVEL MEMBRANE REACTOR; FINAL

    International Nuclear Information System (INIS)

    Shamsuddin Ilias, Ph.d., P.E.; Franklin G. King, D.Sc.

    2001-01-01

    With the advances in new inorganic materials and processing techniques, there has been renewed interest in exploiting the benefits of membranes in many industrial applications. Inorganic and composite membranes are being considered as potential candidates for use in membrane-reactor configuration for effectively increasing reaction rate, selectivity and yield of equilibrium limited reactions. To investigate the usefulness of a palladium-ceramic composite membrane in a membrane reactor-separator configuration, we investigated the dehydrogenation of cyclohexane by equilibrium shift. A two-dimensional pseudo-homogeneous reactor model was developed to study the dehydrogenation of cyclohexane by equilibrium shift in a tubular membrane reactor. Radial diffusion was considered to account for the concentration gradient in the radial direction due to permeation through the membrane. For a dehydrogenation reaction, the feed stream to the reaction side contained cyclohexane and argon, while the separation side used argon as the sweep gas. Equilibrium conversion for dehydrogenation of cyclohexane is 18.7%. The present study showed that 100% conversion could be achieved by equilibrium shift using Pd-ceramic membrane reactor. For a feed containing cyclohexane and argon of 1.64 x 10(sup -6) and 1.0 x 10(sup -3) mol/s, over 98% conversion could be readily achieved. The dehydrogenation of cyclohexane was also experimentally investigated in a palladium-ceramic membrane reactor. The Pd-ceramic membrane was fabricated by electroless deposition of palladium on ceramic substrate. The performance of Pd-ceramic membrane was compared with a commercially available hydrogen-selective ceramic membrane. From limited experimental data it was observed that by appropriate choice of feed flow rate and sweep gas rate, the conversion of cyclohexane to benzene and hydrogen can increased to 56% at atmospheric pressure and 200 C in a Pd-ceramic membrane reactor. In the commercial ceramic membrane

  16. Speed Limits for Nonvesicular Intracellular Sterol Transport.

    Science.gov (United States)

    Dittman, Jeremy S; Menon, Anant K

    2017-02-01

    Sterol transport between the endoplasmic reticulum (ER) and plasma membrane (PM) occurs by nonvesicular mechanisms requiring sterol transport proteins (STPs). Here we examine the idea that transport is enhanced at membrane contact sites where the ER is closely apposed to the PM. We conclude that sterol desorption from the membrane, rather than STP-mediated diffusion, is rate limiting in the cellular context, so there is no apparent kinetic benefit to having STP-mediated sterol transfer occur at contact sites. Contact sites may instead compartmentalize lipid synthesis or transport machinery, providing opportunities for regulation. Copyright © 2016 Elsevier Ltd. All rights reserved.

  17. Silicon Micropore-Based Parallel Plate Membrane Oxygenator.

    Science.gov (United States)

    Dharia, Ajay; Abada, Emily; Feinberg, Benjamin; Yeager, Torin; Moses, Willieford; Park, Jaehyun; Blaha, Charles; Wright, Nathan; Padilla, Benjamin; Roy, Shuvo

    2018-02-01

    Extracorporeal membrane oxygenation (ECMO) is a life support system that circulates the blood through an oxygenating system to temporarily (days to months) support heart or lung function during cardiopulmonary failure until organ recovery or replacement. Currently, the need for high levels of systemic anticoagulation and the risk for bleeding are main drawbacks of ECMO that can be addressed with a redesigned ECMO system. Our lab has developed an approach using microelectromechanical systems (MEMS) fabrication techniques to create novel gas exchange membranes consisting of a rigid silicon micropore membrane (SμM) support structure bonded to a thin film of gas-permeable polydimethylsiloxane (PDMS). This study details the fabrication process to create silicon membranes with highly uniform micropores that have a high level of pattern fidelity. The oxygen transport across these membranes was tested in a simple water-based bench-top set-up as well in a porcine in vivo model. It was determined that the mass transfer coefficient for the system using SµM-PDMS membranes was 3.03 ± 0.42 mL O 2 min -1 m -2 cm Hg -1 with pure water and 1.71 ± 1.03 mL O 2 min -1 m -2 cm Hg -1 with blood. An analytic model to predict gas transport was developed using data from the bench-top experiments and validated with in vivo testing. This was a proof of concept study showing adequate oxygen transport across a parallel plate SµM-PDMS membrane when used as a membrane oxygenator. This work establishes the tools and the equipoise to develop future generations of silicon micropore membrane oxygenators. © 2017 International Center for Artificial Organs and Transplantation and Wiley Periodicals, Inc.

  18. [Case-control study on effects of external fixation combined with limited internal fixation for the treatment of Pilon fractures of Rüedi-Allgower type III].

    Science.gov (United States)

    Duan, Da-Peng; You, Wu-Lin; Ji, Le; Zhang, Yong-Tao; Dang, Xiao-Qian; Wang, Kun-Zheng

    2014-01-01

    To analyze the effects of three surgical operations in the treatment of Pilon fracture of Rüedi-Allgower type III, and put forward the best therapeutic method. The clinical data of 33 patients with Pilon fracture who received surgical operations (plaster immobilization group, 10 cases; distal tibia anatomical plate group, 11 cases; external fixation with limited internal fixation group, 12 cases) from October 2009 to January 2012 were analyzed. There were 5 males and 5 females, ranging in age from 24 to 61 years in the plaster immobilization group. There were 7 males and 4 females, ranging in age from 21 to 64 years in the distal tibia anatomical plate group. There were 7 males and 5 females, ranging in age from 23 to 67 years in the external fixation with limited internal fixation group. The Ankle X-ray of Pilon fracture after operation, ankle score, early and late complications were collected. Bourne system was used to evaluate ankle joint function. After 8 months to 3 years follow-up, it was found that three kinds of treatment had significant differences in the outcomes and complications (P external fixation with limited internal fixation group got the best results. The number of anatomic reduction cases in the external fixation with limited internal fixation group (7 cases) and the distal tibia anatomical plate group (8 cases) was more than the plaster immobilization group (2 cases). According to the ankle score, 8 patients got an excellent result, 3 good and 1 poor in the limited internal fixation group ,which was better than those of distal tibia anatomical plate group (5 excellent, 4 good and 2 poor) and the plaster immobilization group (3 excellent, 4 good and 3 poor). The number of early and late complications in the external fixation with limited internal fixation group was more than those in the plaster immobilization group and the distal tibia anatomical plate group (Pexternal fixation with limited internal fixation in the treatment of Pilon fracture

  19. Smart membranes for monitoring membrane based desalination processes

    KAUST Repository

    Laleg-Kirati, Taous-Meriem

    2017-10-12

    Various examples are related to smart membranes for monitoring membrane based process such as, e.g., membrane distillation processes. In one example, a membrane, includes a porous surface and a plurality of sensors (e.g., temperature, flow and/or impedance sensors) mounted on the porous surface. In another example, a membrane distillation (MD) process includes the membrane. Processing circuitry can be configured to monitor outputs of the plurality of sensors. The monitored outputs can be used to determine membrane degradation, membrane fouling, or to provide an indication of membrane replacement or cleaning. The sensors can also provide temperatures or temperature differentials across the porous surface, which can be used to improve modeling or control the MD process.

  20. Evaluation of functional outcome of pilon fractures managed with limited internal fixation and external fixation: A prospective clinical study.

    Science.gov (United States)

    Meena, Umesh Kumar; Bansal, Mahesh Chand; Behera, Prateek; Upadhyay, Rahul; Gothwal, Gyan Chand

    2017-11-01

    The management of pilon fractures is controversial primarily due to the high rate of complications irrespective of the mode of treatment. Limited internal fixation with external fixation is associated with minimal soft tissue handling. This may reduce the chances of wound dehiscence and infection. This study was designed to evaluate the functional and clinical outcomes in patients treated with limited internal fixation combined with external fixation in pilon fractures. This study was conducted as a prospective clinical study on 56 skeletally mature patients with closed fractures with poor skin condition, and with open grade 1 and grade 2 distal tibial intra-articular fractures. All patients were treated with combined limited internal fixation and ankle spanning external fixation. All fractures in this series united with an average time period of union of 18.3weeks (ranging from 13 weeks to 30 weeks). There was no non-union in any case. There was malunion in 4 cases, varus malunion (>5 degree) in 2 cases and recurvatum in another 2 cases). Excellent to good functional results were observed in 88% cases based on the modified Ovadia and Beals score. The mean ankle dorsiflexion and planter flexion movements were 10.2±5.3 degrees and 27.4±7.2 degrees respectively. infections occurred in 6 patients which included 4 pin tract infections and 2 superficial wound infection, all 6 healed after removal of pin tract and with oral antibiotics. The technique of combined external fixation with internal fixation is safe and effective management option for intra-articular distal tibial fractures.

  1. Heat stress causes spatially-distinct membrane re-modelling in K562 leukemia cells.

    Directory of Open Access Journals (Sweden)

    Gábor Balogh

    Full Text Available Cellular membranes respond rapidly to various environmental perturbations. Previously we showed that modulations in membrane fluidity achieved by heat stress (HS resulted in pronounced membrane organization alterations which could be intimately linked to the expression and cellular distribution of heat shock proteins. Here we examine heat-induced membrane changes using several visualisation methods. With Laurdan two-photon microscopy we demonstrate that, in contrast to the enhanced formation of ordered domains in surface membranes, the molecular disorder is significantly elevated within the internal membranes of cells preexposed to mild HS. These results were compared with those obtained by anisotropy, fluorescence lifetime and electron paramagnetic resonance measurements. All probes detected membrane changes upon HS. However, the structurally different probes revealed substantially distinct alterations in membrane heterogeneity. These data call attention to the careful interpretation of results obtained with only a single label. Subtle changes in membrane microstructure in the decision-making of thermal cell killing could have potential application in cancer therapy.

  2. Recent advances on polymeric membranes for membrane reactors

    KAUST Repository

    Buonomenna, M. G.; Choi, Seung Hak

    2012-01-01

    . 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

  3. Engineering a self-driven PVDF/PDA hybrid membranes based on membrane micro-reactor effect to achieve super-hydrophilicity, excellent antifouling properties and hemocompatibility

    Science.gov (United States)

    Li, Jian-Hua; Ni, Xing-Xing; Zhang, De-Bin; Zheng, Hui; Wang, Jia-Bin; Zhang, Qi-Qing

    2018-06-01

    A facile and versatile approach for the preparation of super-hydrophilic, excellent antifouling and hemocompatibility membranes had been developed through the generation in situ of bio-inspired polydopamine (PDA) microspheres on PVDF membranes. SEM images showed that the PDA microspheres were uniformly dispersed on the upper surface and the lower surface of the modified membranes. And there were a great number of PDA microspheres immobilized on the cross-section, but the interconnected pores structure was not destroyed. These facts indicated the existence of membrane micro-reactor effect for the whole membrane structure. Considering the remarkable improvement of hydrophilicity, antifouling properties, and permeation fluxes, we also proposed the cluster phenolic hydroxyl effect for the PVDF/PDA hybrid membranes. And the cluster phenolic hydroxyl effect can be ascribed to the all directions distributed phenolic hydroxyl groups on the whole membrane structure. Besides, the self-driven filtration experiments showed the great wetting ability and permeability of the PVDF/PDA hybrid membranes in filtration process without any external pressure. This implied the existence of accelerating self-driven force after the water flow flowed into the internal of membranes, which contributed to the increase of water flow velocity. All the three aspects were in favor of the enhancement of hydrophilicity, antifouling properties and permeability of the modified membranes. Moreover, the conventional filtration tests, oil/water emulsion filtration tests and protein adsorption tests were also carried out to discuss the practical applications of PVDF/PDA hybrid membranes. And the hemocompatibility of the modified membranes was also proved to enhance greatly through the hemolysis tests and platelet adhesion tests, indicating that the membranes were greatly promising in biomedical applications. The strategy of material modification reported here is substrate-independent and can be extended

  4. Novel, Ceramic Membrane System For Hydrogen Separation

    Energy Technology Data Exchange (ETDEWEB)

    Elangovan, S.

    2012-12-31

    Separation of hydrogen from coal gas represents one of the most promising ways to produce alternative sources of fuel. Ceramatec, teamed with CoorsTek and Sandia National Laboratories has developed materials technology for a pressure driven, high temperature proton-electron mixed conducting membrane system to remove hydrogen from the syngas. This system separates high purity hydrogen and isolates high pressure CO{sub 2} as the retentate, which is amenable to low cost capture and transport to storage sites. The team demonstrated a highly efficient, pressure-driven hydrogen separation membrane to generate high purity hydrogen from syngas using a novel ceramic-ceramic composite membrane. Recognizing the benefits and limitations of present membrane systems, the all-ceramic system has been developed to address the key technical challenges related to materials performance under actual operating conditions, while retaining the advantages of thermal and process compatibility offered by the ceramic membranes. The feasibility of the concept has already been demonstrated at Ceramatec. This project developed advanced materials composition for potential integration with water gas shift rectors to maximize the hydrogenproduction.

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

    Directory of Open Access Journals (Sweden)

    Katerina V. Matorina

    2015-10-01

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

  6. Choroidal neovascular membrane

    OpenAIRE

    Bhatt Nitul; Diamond James; Jalali Subhadra; Das Taraprasad

    1998-01-01

    Choroidal neovascular membrane in the macular area is one of the leading causes of severe visual loss. Usually a manifestation in elderly population, it is often associated with age-related macular degeneration. The current mainstay of management is early diagnosis, usually by fundus examination, aided by angiography and photocoagulation in selected cases. Various other modalities of treatment including surgery are being considered as alternate options, but with limited success. The purpose o...

  7. Membrane computing: brief introduction, recent results and applications.

    Science.gov (United States)

    Păun, Gheorghe; Pérez-Jiménez, Mario J

    2006-07-01

    The internal organization and functioning of living cells, as well as their cooperation in tissues and higher order structures, can be a rich source of inspiration for computer science, not fully exploited at the present date. Membrane computing is an answer to this challenge, well developed at the theoretical (mathematical and computability theory) level, already having several applications (via usual computers), but without having yet a bio-lab implementation. After briefly discussing some general issues related to natural computing, this paper provides an informal introduction to membrane computing, focused on the main ideas, the main classes of results and of applications. Then, three recent achievements, of three different types, are briefly presented, with emphasis on the usefulness of membrane computing as a framework for devising models of interest for biological and medical research.

  8. 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.

  9. [Changes in polarization of myometrial cells plasma and internal mitochondrial membranes under calixarenes action as inhibitors of plasma membrane Na+, K+-ATPase].

    Science.gov (United States)

    Danylovych, H V; Danylovych, Iu V; Kolomiiets', O V; Kosterin, S O; Rodik, R V; Cherenok, S O; Kal'chenko, V I; Chunikhin, O Iu; Horchev, V F; Karakhim, S O

    2012-01-01

    The influence of supramolecular macrocyclic compounds--calix[4]arenes C-97, C-99, C-107, which are ouabainomymetic high affinity inhibitors of Na+, K(+)-ATPase, on the polarization level of plasmic and mitochondrial membranes of rat uterine smooth muscle cells was investigated. The influence of these compounds on the myocytes characteristic size was studied. By using a confocal microscopy and specific for mitochondrial MitoTracker Orange CM-H2TMRos dye it was proved that the potential-sensitive fluorescent probe DiOC6(3) interacts with mitochondria. Artificial potential collapse of plasmic membrane in this case was modeled by myocytes preincubation with ouabain (1 mM). Further experiments performed using the method of flow cytometry with DiOC6(3) have shown that the compounds C-97, C-99 and C-107 at concentration 50-100 nM caused depolarization of the plasma membrane (at the level of 30% relative to control values) in conditions of artificial collapse of mitochondrial potential by myocytes preincubation in the presence of 5 mM of sodium azide. Under artificial sarcolemma depolarization by ouabain, calixarenes C-97, C-99 and C-107 at 100 nM concentrations caused a transient increase of mitochondrial membrane potential, that is 40% of the control level and lasted about 5 minutes. Calixarenes C-99 and C-107 caused a significant increase in fluorescence of myocytes in these conditions, which was confirmed by confocal microscopy too. It was proved by photon correlation spectroscopy method that the C-99 and C-107 caused an increase of characteristic size of myocytes.

  10. Electrochemically Deposited Nickel Membranes; Process-Microstructure-Property Relationships

    DEFF Research Database (Denmark)

    Jensen, Jens Dahl; Pantleon, Karen; Somers, Marcel A.J.

    2003-01-01

    This paper reports on the manufacturing, surface morphology, internal structure and mechanical properties of Ni-foils used as membranes in reference-microphones. Two types of foils, referred to as S-type and 0-type foils, were electrochemically deposited from a Watts-type electrolyte, with (S...

  11. A Membrane Model from Implicit Elasticity Theory

    Science.gov (United States)

    Freed, A. D.; Liao, J.; Einstein, D. R.

    2014-01-01

    A Fungean solid is derived for membranous materials as a body defined by isotropic response functions whose mathematical structure is that of a Hookean solid where the elastic constants are replaced by functions of state derived from an implicit, thermodynamic, internal-energy function. The theory utilizes Biot’s (1939) definitions for stress and strain that, in 1-dimension, are the stress/strain measures adopted by Fung (1967) when he postulated what is now known as Fung’s law. Our Fungean membrane model is parameterized against a biaxial data set acquired from a porcine pleural membrane subjected to three, sequential, proportional, planar extensions. These data support an isotropic/deviatoric split in the stress and strain-rate hypothesized by our theory. These data also demonstrate that the material response is highly non-linear but, otherwise, mechanically isotropic. These data are described reasonably well by our otherwise simple, four-parameter, material model. PMID:24282079

  12. Internal transport barrier and β limit in ohmically heated plasma in TUMAN-3M

    International Nuclear Information System (INIS)

    Andreiko, M.V.; Askinazi, L.G.; Golant, V.E.

    2001-01-01

    An Internal Transport Barrier (ITB) was found in ohmically heated plasma in TUMAN-3M (R 0 =53 cm, a l =22 cm - circular limiter configuration, B t ≤0.7T, I p ≤175 kA, ≤6.0·10 19 m -3 ). The barrier reveals itself as a formation of a steep gradient on electron temperature and density radial profiles. The regions with reduced diffusion and electron thermal diffusivity are in between r=0.5a and r=0.7a. The ITB appears more frequently in the shots with higher plasma current. At lower currents (I p N limit in the ohmically heated plasma are presented. Stored energy was measured using diamagnetic loops and compared with W calculated from kinetic data obtained by Thomson scattering and microwave interferometry. Measurements of the stored energy and of the β were performed in the ohmic H-mode before and after boronization and in the scenario with the fast Current Ramp-Down in the ohmic H-mode. Maximum value of β T of 2.0 % and β N of 2 were achieved. The β N limit achieved is 'soft' (nondisruptive) limit. The stored energy slowly decays after the Current Ramp-Down. No correlation was found between beta restriction and MHD phenomena. (author)

  13. Internal transport barrier and β limit in ohmically heated plasma in TUMAN-3M

    International Nuclear Information System (INIS)

    Andreiko, M.V.; Askinazi, L.G.; Golant, V.E.

    1999-01-01

    An Internal Transport Barrier (ITB) was found in ohmically heated plasma in TUMAN-3M (R 0 = 53 cm, a l = 22 cm - circular limiter configuration, B t ≤ 0.7 T, I p ≤ 175 kA, ≤ 6.0·10 19 m -3 ). The barrier reveals itself as a formation of a steep gradient on electron temperature and density radial profiles. The regions with reduced diffusion and electron thermal diffusivity are in between r = 0.5a and r = 0.7a. The ITB appears more frequently in the shots with higher plasma current. At lower currents (I p N limit in the ohmically heated plasma are presented. Stored energy was measured using diamagnetic loops and compared with W calculated from kinetic data obtained by Thomson scattering and microwave interferometry. Measurements of the stored energy and of the β were performed in the ohmic H-mode before and after boronization and in the scenario with the fast Current Ramp-Down in the ohmic H-mode. Maximum value of β T of 2.0% and β N of 2 were achieved. The β N limit achieved is 'soft' (non-disruptive) limit. The stored energy slowly decays after the Current Ramp-Down. No correlation was found between beta restriction and MHD phenomena. (author)

  14. Chemical Imaging of the Cell Membrane by NanoSIMS

    International Nuclear Information System (INIS)

    Weber, P.K.; Kraft, M.L.; Frisz, J.F.; Carpenter, K.J.; Hutcheon, I.D.

    2010-01-01

    The existence of lipid microdomains and their role in cell membrane organization are currently topics of great interest and controversy. The cell membrane is composed of a lipid bilayer with embedded proteins that can flow along the two-dimensional surface defined by the membrane. Microdomains, known as lipid rafts, are believed to play a central role in organizing this fluid system, enabling the cell membrane to carry out essential cellular processes, including protein recruitment and signal transduction. Lipid rafts are also implicated in cell invasion by pathogens, as in the case of the HIV. Therefore, understanding the role of lipid rafts in cell membrane organization not only has broad scientific implications, but also has practical implications for medical therapies. One of the major limitations on lipid organization research has been the inability to directly analyze lipid composition without introducing artifacts and at the relevant length-scales of tens to hundreds of nanometers. Fluorescence microscopy is widely used due to its sensitivity and specificity to the labeled species, but only the labeled components can be observed, fluorophores can alter the behavior of the lipids they label, and the length scales relevant to imaging cell membrane domains are between that probed by fluorescence resonance energy transfer (FRET) imaging (<10 nm) and the diffraction limit of light. Topographical features can be imaged on this length scale by atomic force microscopy (AFM), but the chemical composition of the observed structures cannot be determined. Immuno-labeling can be used to study the distribution of membrane proteins at high resolution, but not lipid composition. We are using imaging mass spectrometry by secondary ion mass spectrometry (SIMS) in concert with other high resolution imaging methods to overcome these limitations. The experimental approach of this project is to combine molecule-specific stable isotope labeling with high-resolution SIMS using a

  15. Separation of hydrogen from dilute streams (e.g. using membranes)

    Energy Technology Data Exchange (ETDEWEB)

    Brueschke, H.E.A. [Sulzer Chemtech GmbH Membrantechnik, Neunkirchen (Germany)

    2003-07-01

    As a conclusion it can be stated that the use of membranes in the separation and purification of hydrogen is still limited. In areas where hydrogen at not too high purity can be recovered from otherwise low value gas mixtures, like in the examples given above, the application of membranes has developed into a proven state-of-art technology. Where high purity hydrogen at high pressure is demanded, still fairly large work is ahead for membrane and process developers. (orig.)

  16. Membranous Dysmenorrhea: A Case Series

    Science.gov (United States)

    Omar, Hatim A.; Smith, Shawn J.

    2007-01-01

    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. PMID:18060329

  17. Conformationally Preorganized Diastereomeric Norbornane-Based Maltosides for Membrane Protein Study

    DEFF Research Database (Denmark)

    Das, Manabendra; Du, Yang; Ribeiro, Orquidea

    2017-01-01

    were generally better at stabilizing membrane proteins than short alkyl chain agents. Furthermore, use of one well-behaving NBM enabled us to attain a marked stabilization and clear visualization of a challenging membrane protein complex using electron microscopy. Thus, this study not only describes......Detergents are essential tools for functional and structural studies of membrane proteins. However, conventional detergents are limited in their scope and utility, particularly for eukaryotic membrane proteins. Thus, there are major efforts to develop new amphipathic agents with enhanced properties....... Here, a novel class of diastereomeric agents with a preorganized conformation, designated norbornane-based maltosides (NBMs), were prepared and evaluated for their ability to solubilize and stabilize membrane proteins. Representative NBMs displayed enhanced behaviors compared to n...

  18. Purification of crude biodiesel using dry washing and membrane technologies

    Directory of Open Access Journals (Sweden)

    I.M. Atadashi

    2015-12-01

    Full Text Available Purification of crude biodiesel is mandatory for the fuel to meet the strict international standard specifications for biodiesel. Therefore, this paper carefully analyzed recently published literatures which deal with the purification of biodiesel. As such, dry washing technologies and the most recent membrane biodiesel purification process have been thoroughly examined. Although purification of biodiesel using dry washing process involving magnesol and ion exchange resins provides high-quality biodiesel fuel, considerable amount of spent absorbents is recorded, besides the skeletal knowledge on its operating process. Further, recent findings have shown that biodiesel purification using membrane technique could offer high-quality biodiesel fuel with less wastewater discharges. Thus, both researchers and industries are expected to benefit from the development of membrane technique in purifying crude biodiesel. As well biodiesel purification via membranes has been shown to be environmentally friendly. For these reasons, it is important to explore and exploit membrane technology to purify crude biodiesel.

  19. Limits to Party Autonomy in International Commercial Arbitration

    OpenAIRE

    Giuditta Cordero-Moss

    2014-01-01

    International contracts are often written in a standardised manner and without taking into consideration the applicable law. This may create the illusion that the contract is the only basis for the parties' rights and obligations, especially when the contract contains an arbitration clause. Using two typical contract clauses as an illustration (force majeure clause and entire agreement clause), this article analyses the extent to which an international contract, eventhough it contains an arbi...

  20. Use of biomimetic forward osmosis membrane for trace organics removal

    DEFF Research Database (Denmark)

    Madsen, Henrik T.; Bajraktari, Niada; Helix Nielsen, Claus

    2015-01-01

    The use of forward osmosis for the removal of trace organics from water has recently attracted considerable attention as an alternative to traditional pressure driven membrane filtration. However, the existing forward osmosis membranes have been found to be ineffective at rejecting small neutral...... organic pollutants, which limits the applicability of the forward osmosis process. In this study a newly developed biomimetic membrane was tested for the removal of three selected trace organics that can be considered as a bench marking test for a membrane[U+05F3]s ability to reject small neutral organic....... This difference is caused by differences in the transport mechanisms. For the cellulose acetate membrane rejection is controlled by steric hindrance, which results in a size dependent rejection of the trace organics, whereas rejection by the aquaporin membrane is controlled by diffusion of the trace organics...

  1. Exclusive photorelease of signalling lipids at the plasma membrane.

    Science.gov (United States)

    Nadler, André; Yushchenko, Dmytro A; Müller, Rainer; Stein, Frank; Feng, Suihan; Mulle, Christophe; Carta, Mario; Schultz, Carsten

    2015-12-21

    Photoactivation of caged biomolecules has become a powerful approach to study cellular signalling events. Here we report a method for anchoring and uncaging biomolecules exclusively at the outer leaflet of the plasma membrane by employing a photocleavable, sulfonated coumarin derivative. The novel caging group allows quantifying the reaction progress and efficiency of uncaging reactions in a live-cell microscopy setup, thereby greatly improving the control of uncaging experiments. We synthesized arachidonic acid derivatives bearing the new negatively charged or a neutral, membrane-permeant coumarin caging group to locally induce signalling either at the plasma membrane or on internal membranes in β-cells and brain slices derived from C57B1/6 mice. Uncaging at the plasma membrane triggers a strong enhancement of calcium oscillations in β-cells and a pronounced potentiation of synaptic transmission while uncaging inside cells blocks calcium oscillations in β-cells and causes a more transient effect on neuronal transmission, respectively. The precise subcellular site of arachidonic acid release is therefore crucial for signalling outcome in two independent systems.

  2. Regulation of VEGF signaling by membrane traffic.

    Science.gov (United States)

    Horowitz, Arie; Seerapu, Himabindu Reddy

    2012-09-01

    Recent findings have drawn attention to the role of membrane traffic in the signaling of vascular endothelial growth factor (VEGF). The significance of this development stems from the pivotal function of VEGF in vasculogenesis and angiogenesis. The outline of the regulation of VEGF receptor (VEGFR) signaling by membrane traffic is similar to that of the epidermal growth factor receptor (EGFR), a prototype of the intertwining between membrane traffic and signaling. There are, however, unique features in VEGFR signaling that are conferred in part by the involvement of the co-receptor neuropilin (Nrp). Nrp1 and VEGFR2 are integrated into membrane traffic through the adaptor protein synectin, which recruits myosin VI, a molecular motor that drives inward trafficking [17,21,64]. The recent detection of only mild vascular defects in a knockin mouse model that expresses Nrp1 lacking a cytoplasmic domain [104], questions the co-receptor's role in VEGF signaling and membrane traffic. The regulation of endocytosis by ephrin-B2 is another feature unique to VEGR2/3 [18,19], but it awaits a mechanistic explanation. Current models do not fully explain how membrane traffic bridges between VEGFR and the downstream effectors that produce its functional outcome, such as cell migration. VEGF-A appears to accomplish this task in part by recruiting endocytic vesicles carrying RhoA to internalized active VEGFR2 [58]. Copyright © 2012 Elsevier Inc. All rights reserved.

  3. HIGH PERFORMANCE CERIA BASED OXYGEN MEMBRANE

    DEFF Research Database (Denmark)

    2014-01-01

    The invention describes a new class of highly stable mixed conducting materials based on acceptor doped cerium oxide (CeO2-8 ) in which the limiting electronic conductivity is significantly enhanced by co-doping with a second element or co- dopant, such as Nb, W and Zn, so that cerium and the co......-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...

  4. Control of recoil losses in nanomechanical SiN membrane resonators

    Science.gov (United States)

    Borrielli, A.; Marconi, L.; Marin, F.; Marino, F.; Morana, B.; Pandraud, G.; Pontin, A.; Prodi, G. A.; Sarro, P. M.; Serra, E.; Bonaldi, M.

    2016-09-01

    In the context of a recoil damping analysis, we have designed and produced a membrane resonator equipped with a specific on-chip structure working as a "loss shield" for a circular membrane. In this device the vibrations of the membrane, with a quality factor of 107, reach the limit set by the intrinsic dissipation in silicon nitride, for all the modes and regardless of the modal shape, also at low frequency. Guided by our theoretical model of the loss shield, we describe the design rationale of the device, which can be used as effective replacement of commercial membrane resonators in advanced optomechanical setups, also at cryogenic temperatures.

  5. Dual phase oxygen transport membrane for efficient oxyfuel combustion

    International Nuclear Information System (INIS)

    Ramasamy, Madhumidha

    2016-01-01

    Oxygen transport membranes (OTMs) are attracting great interest for the separation of oxygen from air in an energy efficient way. A variety of solid oxide ceramic materials that possess mixed ionic and electronic conductivity (MIEC) are being investigated for efficient oxygen separation (Betz '10, Skinner '03). Unfortunately these materials do not exhibit high degradation stability under harsh ambient conditions such as flue gas containing CO_2, SO_x, H_2O and dust, pressure gradients and high temperatures that are typical in fossil fuel power plants. For this reason, dual phase composite membranes are developed to combine the best characteristics of different compounds to achieve high oxygen permeability and sufficient chemical and mechanical stability at elevated temperatures. In this thesis, the dual phase membrane Ce_0_._8Gd_0_._2O_2_-_δ - FeCo_2O_4 (CGO-FCO) was developed after systematic investigation of various combinations of ionic and electronic conductors. The phase distribution of the composite was investigated in detail using electron microscopes and this analysis revealed the phase interaction leading to grain boundary rock salt phase and formation of perovskite secondary phase. A systematic study explored the onset of phase interactions to form perovskite phase and the role of this unintended phase as pure electronic conductor was identified. Additionally optimization of conventional sintering process to eliminate spinel phase decomposition into rock salt was identified. An elaborate study on the absolute minimum electronic conductor requirement for efficient percolation network was carried out and its influence on oxygen flux value was measured. Oxygen permeation measurements in the temperature range of 600 C - 1000 C under partial pressure gradient provided by air and argon as feed and sweep gases are used to identify limiting transport processes. The dual phase membranes are much more prone to surface exchange limitations because of the limited

  6. Identification of frog photoreceptor plasma and disk membrane proteins by radioiodination

    International Nuclear Information System (INIS)

    Witt, P.L.; Bownds, M.D.

    1987-01-01

    Several functions have been identified for the plasma membrane of the rod outer segment, including control of light-dependent changes in sodium conductance and a sodium-calcium exchange mechanism. However, little is known about its constituent proteins. Intact rod outer segments substantially free of contaminants were prepared in the dark and purified on a density gradient of Percoll. Surface proteins were then labeled by lactoperoxidase-catalyzed radioiodination, and intact rod outer segments were reisolated. Membrane proteins were identified by polyacrylamide gel electrophoresis and autoradiography. The surface proteins labeled included rhodopsin, the major membrane protein, and 12 other proteins. To compare the protein composition of plasma membrane with that of the internal disk membrane, purified rod outer segments were lysed by hypotonic disruption or freeze-thawing, and plasma plus disk membranes were radioiodinated. In these membrane preparations, rhodopsin was the major iodinated constituent, with 12 other proteins also labeled. Autoradiographic evidence indicated some differences in protein composition between disk and plasma membranes. A quantitative comparison of the two samples showed that labeling of two proteins, 24 kilodaltons (kDa) and 13 kDa, was enriched in the plasma membrane, while labeling of a 220-kDa protein was enriched in the disk membrane. These plasma membrane proteins may be associated with important functions such as the light-sensitive conductance and the sodium-calcium exchanger

  7. Reflectivity and thickness analysis of epiretinal membranes using spectral-domain optical coherence tomography

    Directory of Open Access Journals (Sweden)

    Ajay E. Kuriyan

    2016-01-01

    Full Text Available AIM: To compare thickness and reflectivity spectral domain optical coherence tomography (SD-OCT findings in patients with idiopathic epiretinal membranes (ERMs, before and after ERM peeling surgery, with normal controls. METHODS: A retrospective study analyzed SD-OCTs of eyes with ERMs undergoing ERM peeling surgery by one surgeon from 2008 to 2010 and normal control eyes. SD-OCTs were analyzed using a customized algorithm to measure reflectivity and thickness. The relationship between the SD-OCT findings and best corrected visual acuity (BCVA outcomes was also studied. RESULTS: Thirty-four ERM eyes and 12 normal eyes were identified. Preoperative eyes had high reflectivity and thickness of the group of layers from the internal limiting membrane (ILM to the retinal pigment epithelium (RPE and the group of layers from the ILM to the external limiting membrane (ELM. The values of reflectivity of these two groups of layers decreased postoperatively, but were still higher than normal eyes. In contrast, preoperative eyes had lower reflectivity of two 10×15 pixel regions of interest (ROIs incorporating: 1 ELM + outer nuclear layer (ONL and 2 photoreceptor layer (PRL + RPE, compared to controls. The values of reflectivity of these ROIs increased postoperatively, but were still lower than normal controls. A larger improvement in BCVA postoperatively was correlated with a greater degree of abnormal preoperative reflectivity and thickness findings. CONCLUSION: Quantitative differences in reflectivity and thickness between preoperative, postoperative, and normal SD-OCTs allow assessment of changes in the retina secondary to ERM. Our study identified hyperreflective inner retina changes and hyporeflective outer retina changes in patients with ERMs. SD-OCT quantitative measures of reflectivity and/or thickness of specific groups of retinal layers and/or ROIs correlate with improvement in BCVA.

  8. Effect of the preparation conditions on the properties of polyetherimide hollow fibre membranes for gas separation

    Czech Academy of Sciences Publication Activity Database

    Válek, R.; Malý, D.; Peter, Jakub; Gruart, M.

    2017-01-01

    Roč. 75, May (2017), s. 300-304 ISSN 1944-3994. [Membrane Conference of Visegrad Countries - PERMEA and International Conference on Membrane and Electromembrane Processes - MELPRO. Prague, 15.05.2016-19.05.2016] Institutional support: RVO:61389013 Keywords : hollow fiber membrane * asymetric membrane * design of experiments Subject RIV: CG - Electrochemistry OBOR OECD: Electrochemistry (dry cells, batteries, fuel cells, corrosion metals, electrolysis) Impact factor: 1.631, year: 2016 http://www.deswater.com/DWT_abstracts/vol_75/75_2017_300.pdf

  9. Membrane fouling mechanism of biofilm-membrane bioreactor (BF-MBR): Pore blocking model and membrane cleaning.

    Science.gov (United States)

    Zheng, Yi; Zhang, Wenxiang; Tang, Bing; Ding, Jie; Zheng, Yi; Zhang, Zhien

    2018-02-01

    Biofilm membrane bioreactor (BF-MBR) is considered as an important wastewater treatment technology that incorporates advantages of both biofilm and MBR process, as well as can alleviate membrane fouling, with respect to the conventional activated sludge MBR. But, to be efficient, it necessitates the establishment of proper methods for the assessment of membrane fouling. Four Hermia membrane blocking models were adopted to quantify and evaluate the membrane fouling of BF-MBR. The experiments were conducted with various operational conditions, including membrane types, agitation speeds and transmembrane pressure (TMP). Good agreement between cake formation model and experimental data was found, confirming the validity of the Hermia models for assessing the membrane fouling of BF-MBR and that cake layer deposits on membrane. Moreover, the influences of membrane types, agitation speeds and transmembrane pressure on the Hermia pore blocking coefficient of cake layer were investigated. In addition, the permeability recovery after membrane cleaning at various operational conditions was studied. This work confirms that, unlike conventional activated sludge MBR, BF-MBR possesses a low degree of membrane fouling and a higher membrane permeability recovery after cleaning. Copyright © 2017 Elsevier Ltd. All rights reserved.

  10. Unstable ‘black branes’ from scaled membranes at large D

    Energy Technology Data Exchange (ETDEWEB)

    Dandekar, Yogesh; Mazumdar, Subhajit; Minwalla, Shiraz; Saha, Arunabha [Department of Theoretical Physics, Tata Institute of Fundamental Research,Homi Bhabha Road, Mumbai, 400005 (India)

    2016-12-28

    It has recently been demonstrated that the dynamics of black holes at large D can be recast as a set of non gravitational membrane equations. These membrane equations admit a simple static solution with shape S{sup D−p−2}×R{sup p,1}. In this note we study the equations for small fluctuations about this solution in a limit in which amplitude and length scale of the fluctuations are simultaneously scaled to zero as D is taken to infinity. We demonstrate that the resultant nonlinear equations, which capture the Gregory-Laflamme instability and its end point, exactly agree with the effective dynamical ‘black brane’ equations of Emparan Suzuki and Tanabe. Our results thus identify the ‘black brane’ equations as a special limit of the membrane equations and so unify these approaches to large D black hole dynamics.

  11. Non-abelian gauge bosons in the compactified bosonic membrane theory

    International Nuclear Information System (INIS)

    Kubo, J.

    1988-01-01

    We consider the bosonic membrane compactified on a torus. The membrane motion is stabilized by a topologically non-trivial background. We find that, in the narrow membrane limit, the mass formula to O(ℎ) reduces to exactly the same form as that of the compactified closed bosonic string theory, and we obtain (almost) massless vector bosons in the adjoint representation of a simply laced Lie group in D=27. This is only dimension at which the graviton and gauge bosons may coexist in that background. (orig.)

  12. Pervaporation separation of ethanol-water mixtures using polyethylenimine composite membranes

    Science.gov (United States)

    Neidlinger, H.H.; Schissel, P.O.; Orth, R.A.

    1985-06-19

    Synthetic, organic, polymeric membranes were prepared from polyethylenimine for use with pervaporation apparatus in the separation of ethanol-water mixtures. The polymeric material was prepared in dilute aqueous solution and coated onto a polysulfone support film, from which excess polymeric material was subsequently removed. Cross-links were then generated by limited exposure to toluene-2,4-diisocyanate solution, after which the prepared membrane was heat-cured. The resulting membrane structures showed high selectivity in permeating ethanol or water over a wide range of feed concentrations. 2 tabs.

  13. Potentialities of a Membrane Reactor with Laccase Grafted Membranes for the Enzymatic Degradation of Phenolic Compounds in Water

    Directory of Open Access Journals (Sweden)

    Vorleak Chea

    2014-10-01

    Full Text Available This paper describes the degradation of phenolic compounds by laccases from Trametes versicolor in an enzymatic membrane reactor (EMR. The enzymatic membranes were prepared by grafting laccase on a gelatine layer previously deposited onto α-alumina tubular membranes. The 2,6-dimethoxyphenol (DMP was selected  from among the three different phenolic compounds tested (guaiacol, 4-chlorophenol and DMP to study the performance of the EMR in dead end configuration. At the lowest feed substrate concentration tested (100 mg·L−1, consumption increased with flux (up to 7.9 × 103 mg·h−1·m−2 at 128 L·h−1·m−2, whereas at the highest substrate concentration (500 mg·L−1, it was shown that the reaction was limited by the oxygen content.

  14. A rare case of large isolated internal iliac artery aneurysm with ureteral obstruction and hydronephrosis: Compression symptoms are limitation for endovascular procedures.

    Science.gov (United States)

    Nenezic, Dragoslav; Tanaskovic, Slobodan; Gajin, Predrag; Ilijevski, Nenad; Novakovic, Aleksandra; Radak, Djordje

    2015-04-01

    In this report, we aim to present a rare case of isolated internal iliac artery aneurysm with associated left ureteric obstruction and consequent hydronephrosis. A 66-year-old male patient was admitted for occasional pain in the lower back that appeared one month earlier. CT arteriography revealed isolated internal iliac artery (diameter 99 mm) with ureteral obstruction, hydroureter and left kidney hydronephrosis occurrence. Aneurysm was resected, after six months the patient was doing well. Bearing in mind that 77% of the patients with isolated internal iliac artery have symptoms caused by aneurysmal compression on adjacent organs, we wanted to highlight that despite the amazing expansion of endovascular procedures in the last decades, its therapeutic effect in isolated internal iliac artery's treatment is to a great extent limited since compression symptoms cannot be solved. Open surgery remains the gold standard for isolated internal iliac artery's treatment considering significant limitations of endovascular procedures due to the inability to eliminate problems caused by compression. © The Author(s) 2014 Reprints and permissions: sagepub.co.uk/journalsPermissions.nav.

  15. Lateral mobility of plasma membrane lipids in dividing Xenopus eggs.

    Science.gov (United States)

    Tetteroo, P A; Bluemink, J G; Dictus, W J; van Zoelen, E J; de Laat, S W

    1984-07-01

    The lateral mobility of plasma membrane lipids was analyzed during first cleavage of Xenopus laevis eggs by fluorescence photobleaching recovery (FPR) measurements, using the lipid analogs 5-(N-hexadecanoyl)aminofluorescein ("HEDAF") and 5-(N-tetradecanoyl)aminofluorescein ("TEDAF") as probes. The preexisting plasma membrane of the animal side showed an inhomogeneous, dotted fluorescence pattern after labeling and the lateral mobility of both probes used was below the detection limits of the FPR method (D much less than 10(-10) cm2/sec). In contrast, the preexisting plasma membrane of the vegetal side exhibited homogeneous fluorescence and the lateral diffusion coefficient of both probes used was relatively high (HEDAF, D = 2.8 X 10(-8) cm2/sec; TEDAF, D = 2.4 X 10(-8) cm2/sec). In the cleaving egg visible transfer of HEDAF or TEDAF from prelabeled plasma membrane to the new membrane in the furrow did not occur, even on the vegetal side. Upon labeling during cleavage, however, the new membrane was uniformly labeled and both probes were mobile, as in the vegetal preexisting plasma membrane. These data show that the membrane of the dividing Xenopus egg comprises three macrodomains: (i) the animal preexisting plasma membrane; (ii) the vegetal preexisting plasma membrane; (iii) the new furrow membrane.

  16. Efficiency Limits of Solar Energy Harvesting via Internal Photoemission in Carbon Materials

    Directory of Open Access Journals (Sweden)

    Svetlana V. Boriskina

    2018-02-01

    Full Text Available We describe strategies to estimate the upper limits of the efficiency of photon energy harvesting via hot electron extraction from gapless absorbers. Gapless materials such as noble metals can be used for harvesting the whole solar spectrum, including visible and near-infrared light. The energy of photo-generated non-equilibrium or ‘hot’ charge carriers can be harvested before they thermalize with the crystal lattice via the process of their internal photo-emission (IPE through the rectifying Schottky junction with a semiconductor. However, the low efficiency and the high cost of noble metals necessitates the search for cheaper abundant alternative materials, and we show here that carbon can serve as a promising IPE material candidate. We compare the upper limits of performance of IPE photon energy-harvesting platforms, which incorporate either gold or carbon as the photoactive material where hot electrons are generated. Through a combination of density functional theory, joint electron density of states calculations, and Schottky diode efficiency modeling, we show that the material electron band structure imposes a strict upper limit on the achievable efficiency of the IPE devices. Our calculations reveal that graphite is a good material candidate for the IPE absorber for harvesting visible and near-infrared photons. Graphite electron density of states yields a sizeable population of hot electrons with energies high enough to be collected across the potential barrier. We also discuss the mechanisms that prevent the IPE device efficiency from reaching the upper limits imposed by their material electron band structures. The proposed approach is general and allows for efficient pre-screening of materials for their potential use in IPE energy converters and photodetectors within application-specific spectral windows.

  17. Plasma membrane isolation using immobilized concanavalin A magnetic beads.

    Science.gov (United States)

    Lee, Yu-Chen; Srajer Gajdosik, Martina; Josic, Djuro; Lin, Sue-Hwa

    2012-01-01

    Isolation of highly purified plasma membranes is the key step in constructing the plasma membrane proteome. Traditional plasma membrane isolation method takes advantage of the differential density of organelles. While differential centrifugation methods are sufficient to enrich for plasma membranes, the procedure is lengthy and results in low recovery of the membrane fraction. Importantly, there is significant contamination of the plasma membranes with other organelles. The traditional agarose affinity matrix is suitable for isolating proteins but has limitation in separating organelles due to the density of agarose. Immobilization of affinity ligands to magnetic beads allows separation of affinity matrix from organelles through magnets and could be developed for the isolation of organelles. We have developed a simple method for isolating plasma membranes using lectin concanavalin A (ConA) magnetic beads. ConA is immobilized onto magnetic beads by binding biotinylated ConA to streptavidin magnetic beads. The ConA magnetic beads are used to bind glycosylated proteins present in the membranes. The bound membranes are solubilized from the magnetic beads with a detergent containing the competing sugar alpha methyl mannoside. In this study, we describe the procedure of isolating rat liver plasma membranes using sucrose density gradient centrifugation as described by Neville. We then further purify the membrane fraction by using ConA magnetic beads. After this purification step, main liver plasma membrane proteins, especially the highly glycosylated ones and proteins containing transmembrane domains could be identified by LC-ESI-MS/MS. While not described here, the magnetic bead method can also be used to isolate plasma membranes from cell lysates. This membrane purification method should expedite the cataloging of plasma membrane proteome.

  18. Pitfalls in Using Limitation Clauses in the International General Conditions ECE 188 and Orgalime S 2000

    DEFF Research Database (Denmark)

    Henschel, Rene Franz

    2008-01-01

    various individual provisions contained in the general conditions - for example limitation of the right to require repair and further limitation of liability. If this is not motivated by the circumstances surrounding the particular contract, the parties risk creating imbalances in the otherwise well-balanced......The article centers on the rules on the limitation of liability in the general conditions ECE 188 and Orgalime S 2000. ECE 188 differ considerably from S 2000, as the provisions in ECE 188 do not give the necessary consideration to the development in industry practices and legal rules, including...... the approximation and harmonization of legal systems that have taken place during the last 50 years. S 2000 reflects an international trend that increasingly recognizes the importance of striking a balance between the interests of the parties. However, in practice the parties often derogate considerably from...

  19. Continuous esterification to produce biodiesel by SPES/PES/NWF composite catalytic membrane in flow-through membrane reactor: experimental and kinetic studies.

    Science.gov (United States)

    Shi, Wenying; He, Benqiao; Cao, Yuping; Li, Jianxin; Yan, Feng; Cui, Zhenyu; Zou, Zhiqun; Guo, Shiwei; Qian, Xiaomin

    2013-02-01

    A novel composite catalytic membrane (CCM) was prepared from sulfonated polyethersulfone (SPES) and polyethersulfone (PES) blend supported by non-woven fabrics, as a heterogeneous catalyst to produce biodiesel from continuous esterification of oleic acid with methanol in a flow-through mode. A kinetic model of esterification was established based on a plug-flow assumption. The effects of the CCM structure (thickness, area, porosity, etc.), reaction temperature and the external and internal mass transfer resistances on esterification were investigated. The results showed that the CCM structure had a significant effect on the acid conversion. The external mass transfer resistance could be neglected when the flow rate was over 1.2 ml min(-1). The internal mass transfer resistance impacted on the conversion when membrane thickness was over 1.779 mm. An oleic acid conversion kept over 98.0% for 500 h of continuous running. The conversions obtained from the model are in good agreement with the experimental data. Copyright © 2012 Elsevier Ltd. All rights reserved.

  20. Internal phase transition induced by external forces in Finsler geometric model for membranes

    Science.gov (United States)

    Koibuchi, Hiroshi; Shobukhov, Andrey

    2016-10-01

    In this paper, we numerically study an anisotropic shape transformation of membranes under external forces for two-dimensional triangulated surfaces on the basis of Finsler geometry. The Finsler metric is defined by using a vector field, which is the tangential component of a three-dimensional unit vector σ corresponding to the tilt or some external macromolecules on the surface of disk topology. The sigma model Hamiltonian is assumed for the tangential component of σ with the interaction coefficient λ. For large (small) λ, the surface becomes oblong (collapsed) at relatively small bending rigidity. For the intermediate λ, the surface becomes planar. Conversely, fixing the surface with the boundary of area A or with the two-point boundaries of distance L, we find that the variable σ changes from random to aligned state with increasing of A or L for the intermediate region of λ. This implies that an internal phase transition for σ is triggered not only by the thermal fluctuations, but also by external mechanical forces. We also find that the frame (string) tension shows the expected scaling behavior with respect to A/N (L/N) at the intermediate region of A (L) where the σ configuration changes between the disordered and ordered phases. Moreover, we find that the string tension γ at sufficiently large λ is considerably smaller than that at small λ. This phenomenon resembles the so-called soft-elasticity in the liquid crystal elastomer, which is deformed by small external tensile forces.

  1. Membrane dynamics

    DEFF Research Database (Denmark)

    Bendix, Pól Martin

    2015-01-01

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

  2. Inverse colloidal crystal membranes for hydrophobic interaction membrane chromatography.

    Science.gov (United States)

    Vu, Anh T; Wang, Xinying; Wickramasinghe, S Ranil; Yu, Bing; Yuan, Hua; Cong, Hailin; Luo, Yongli; Tang, Jianguo

    2015-08-01

    Hydrophobic interaction membrane chromatography has gained interest due to its excellent performance in the purification of humanized monoclonal antibodies. The membrane material used in hydrophobic interaction membrane chromatography has typically been commercially available polyvinylidene fluoride. In this contribution, newly developed inverse colloidal crystal membranes that have uniform pores, high porosity and, therefore, high surface area for protein binding are used as hydrophobic interaction membrane chromatography membranes for humanized monoclonal antibody immunoglobulin G purification. The capacity of the inverse colloidal crystal membranes developed here is up to ten times greater than commercially available polyvinylidene fluoride membranes with a similar pore size. This work highlights the importance of developing uniform pore size high porosity membranes in order to maximize the capacity of hydrophobic interaction membrane chromatography. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  3. Electrically driven ion separations and nanofiltration through membranes coated with polyelectrolyte multilayers

    Science.gov (United States)

    White, Nicholas

    Polyelectrolyte multilayer (PEM) films deposited using the layer-by-layer (LBL) method are attractive for their simple deposition, tailorable nature, scalability, and charge or size-based selectivity for solutes. This dissertation explores ion separations in electrodialysis (ED) and solute removal through nanofiltration with PEMs deposited on polymer membranes. ED membranes typically exhibit modest selectivities between monovalent and divalent ions. In contrast, this work shows that K+/Mg 2+ ED selectivities reach values >1000 when using Nafion 115 cation-exchange membranes coated with multilayer poly(4-styrenesulfonate) (PSS)/protonated poly(allylamine) (PAH) films. For comparison, the corresponding K+ /Mg2+ selectivity of bare Nafion 115 is salt concentrations, the K+ transference number approaches unity and the K+/Mg2+ selectivity is >20,000, presumably because the applied current is below the limiting value for K+ and H+ transport is negligible at this high K+ concentration. The high selectivities of these membranes may enable electrodialysis applications such as purification of salts that contain divalent or trivalent ions. The high ED selectivities of (PAH/PSS)5PAH-coated Nafion membranes translate to separations with Li+/Co2+ and K +/La3+. Even with adsorption of only 3 polyelectrolyte layers, Nafion membranes exhibit a Li+/Co2+ selectivity >23. However, the resistance to monovalent-ion passage does not decrease significantly with fewer polyelectrolyte layers. At overlimiting currents, hydroxides from water splitting form insoluble metal hydroxides to foul the membrane. With 0.1 M source-phase salt concentrations, transference numbers for monovalent cations approach unity and selectivities are >5000 because the diffusion-limited K+ or Li+ currents exceed the applied current. However, ED selectivities gradually decline with time. Thus, future research should aim to increase membrane stability and limiting currents to fully exploit the remarkable selectivity

  4. Force-dependent breaching of the basement membrane.

    Science.gov (United States)

    Chang, Tammy T; Thakar, Dhruv; Weaver, Valerie M

    2017-01-01

    Clinically, non-invasive carcinomas are confined to the epithelial side of the basement membrane and are classified as benign, whereas invasive cancers invade through the basement membrane and thereby acquire the potential to metastasize. Recent findings suggest that, in addition to protease-mediated degradation and chemotaxis-stimulated migration, basement membrane invasion by malignant cells is significantly influenced by the stiffness of the associated interstitial extracellular matrix and the contractility of the tumor cells that is dictated in part by their oncogenic genotype. In this review, we highlight recent findings that illustrate unifying molecular mechanisms whereby these physical cues contribute to tissue fibrosis and malignancy in three epithelial organs: breast, pancreas, and liver. We also discuss the clinical implications of these findings and the biological properties and clinical challenges linked to the unique biology of each of these organs. Copyright © 2017 International Society of Matrix Biology. Published by Elsevier B.V. All rights reserved.

  5. Ceramic membranes for high temperature hydrogen separation

    Energy Technology Data Exchange (ETDEWEB)

    Fain, D.E.; Roettger, G.E. [Oak Ridge K-25 Site, TN (United States)

    1996-08-01

    Ceramic gas separation membranes can provide very high separation factors if the pore size is sufficiently small to separate gas molecules by molecular sieving and if oversized pores are adequately limited. Ceramic membranes typically have some pores that are substantially larger than the mean pore size and that should be regarded as defects. To assess the effects of such defects on the performance of ceramic membranes, a simple mathematical model has been developed to describe flow through a gas separation membrane that has a primary mode of flow through very small pores but that has a secondary mode of flow through undesirably large pores. This model permits separation factors to be calculated for a specified gas pair as a function of the molecular weights and molecular diameters of the gases, the membrane pore diameter, and the diameter and number of defects. This model will be described, and key results from the model will be presented. The separation factors of the authors membranes continue to be determined using a permeance test system that measures flows of pure gases through a membrane at temperatures up to 275{degrees}C. A primary goal of this project for FY 1996 is to develop a mixed gas separation system for measuring the separation efficiency of membranes at higher temperatures. Performance criteria have been established for the planned mixed gas separation system and design of the system has been completed. The test system is designed to measure the separation efficiency of membranes at temperatures up to 600{degrees}C and pressures up to 100 psi by separating the constituents of a gas mixture containing hydrogen. The system will accommodate the authors typical experimental membrane that is tubular and has a diameter of about 9 mm and a length of about 23 cm. The design of the new test system and its expected performance will be discussed.

  6. The enduring legacy of the “constant-field equation” in membrane ion transport

    Science.gov (United States)

    2017-01-01

    In 1943, David Goldman published a seminal paper in The Journal of General Physiology that reported a concise expression for the membrane current as a function of ion concentrations and voltage. This body of work was, and still is, the theoretical pillar used to interpret the relationship between a cell’s membrane potential and its external and/or internal ionic composition. Here, we describe from an historical perspective the theory underlying the constant-field equation and its application to membrane ion transport. PMID:28931632

  7. Membrane separation systems---A research and development needs assessment

    Energy Technology Data Exchange (ETDEWEB)

    Baker, R.W. (Membrane Technology and Research, Inc., Menlo Park, CA (USA)); Cussler, E.L. (Minnesota Univ., Minneapolis, MN (USA). Dept. of Chemical Engineering and Materials Science); Eykamp, W. (California Univ., Berkeley, CA (USA)); Koros, W.J. (Texas Univ., Austin, TX (USA)); Riley, R.L. (Separation Systems Technology, San Diego, CA (USA)); Strathmann, H. (Fraunhofer-Institut fuer Grenzflaech

    1990-03-01

    Membrane based separation technology, a relative newcomer on the separations scene, has demonstrated the potential of saving enormous amounts of energy in the processing industries if substituted for conventional separation systems. Over 1 quad annually, out of 2.6, can possibly be saved in liquid-to-gas separations, alone, if membrane separation systems gain wider acceptance, according to a recent DOE/OIP (DOE/NBM-80027730 (1986)) study. In recent years great strides have been made in the field and offer even greater energy savings in the future when substituted for other conventional separation techniques such as distillation, evaporation, filtration, sedimentation, and absorption. An assessment was conducted by a group of six internationally known membrane separations experts who examined the worldwide status of research in the seven major membrane areas. This encompassed four mature technology areas: reverse osmosis, micorfiltration, ultrafiltration, and electrodialysis; two developing areas: gas separation and and pervaporation; and one emerging technology: facilitated transport. Particular attention was paid to identifying the innovative processes currently emerging, and even further improvements which could gain wider acceptance for the more mature membrane technology. The topics that were pointed out as having the greatest research emphasis are pervaporation for organic-organic separations; gas separation; micorfiltration; an oxidant-resistant reverse osmosis membrane; and a fouling-resistant ultrafiltration membrane. 35 refs., 6 figs., 22 tabs.

  8. OXIDATIVE COUPLING OF METHANE USING INORGANIC MEMBRANE REACTORS

    Energy Technology Data Exchange (ETDEWEB)

    Dr. Y.H. Ma; Dr. W.R. Moser; Dr. A.G. Dixon; Dr. A.M. Ramachandra; Dr. Y. Lu; C. Binkerd

    1998-04-01

    The objective of this research is to study the oxidative coupling of methane in catalytic inorganic membrane reactors. A specific target is to achieve conversion of methane to C{sub 2} hydrocarbons at very high selectivity and higher yields than in conventional non-porous, co-feed, fixed bed reactors by controlling the oxygen supply through the membrane. A membrane reactor has the advantage of precisely controlling the rate of delivery of oxygen to the catalyst. This facility permits balancing the rate of oxidation and reduction of the catalyst. In addition, membrane reactors minimize the concentration of gas phase oxygen thus reducing non selective gas phase reactions, which are believed to be a main route for the formation of CO{sub x} products. Such gas phase reactions are a cause of decreased selectivity in the oxidative coupling of methane in conventional flow reactors. Membrane reactors could also produce higher product yields by providing better distribution of the reactant gases over the catalyst than the conventional plug flow reactors. Membrane reactor technology also offers the potential for modifying the membranes both to improve catalytic properties as well as to regulate the rate of the permeation/diffusion of reactants through the membrane to minimize by-product generation. Other benefits also exist with membrane reactors, such as the mitigation of thermal hot-spots for highly exothermic reactions such as the oxidative coupling of methane. The application of catalytically active inorganic membranes has potential for drastically increasing the yield of reactions which are currently limited by either thermodynamic equilibria, product inhibition, or kinetic selectivity.

  9. Removal of Radioactive Pollutants by Liquid Emulsion Membrane From Liquid Waste

    International Nuclear Information System (INIS)

    Yossef, Y.A.A.

    2013-01-01

    Radioactive liquid waste should be safely managed because it is potentially hazardous to human health and the environment. Several methods were used for treatment of liquid waste, such as liquid emulsion membrane (LEM). In this work, liquid emulsion membrane using Tri-butyl phosphate (TBP) plus Bis (2-ethylhexyl) phosphate (HDEHP) as mobile carriers, hydrochloric acid (HCl) as stripping agents and an emulsifying agent (span 80) was used for the extraction of uranium ions from radioactive liquid waste. Various parameters influencing the permeation of uranium ions through the membrane have been optimized to separate uranium ions from radioactive liquid waste such as: the effects of membrane material, carrier concentration, operating conditions, etc. were examined; moreover, the transport mechanism of this uranium was also studied. The internal mass transfer in the water/oil (W/O) emulsion drop, the external mass transfer around the drop, the rates of formation, and the decomposition of the complex at the external aqueous-organic interface were considered. The results show that, the liquid emulsion membrane which consists of (25% by volume HDEHP, 0.005 M + 75% by volume TBP, 0.01 M) as extractant (carrier), span 80, 4% (v/v) (sorbitan monooleate) as surfactant agent, hydrochloric acid (HCl), (1.0 M) as stripping agent. From the results, the maximum extraction percent of uranium ions (nearly about of 100%) occurred at the operating conditions: stirring speed =500 rpm, the ratio between LEM and feed phase (liquid waste) = 20 ml: 100 ml, the ratio between organic phase (membrane phase) to internal aqueous phase (stripping phase) = 1.0 and the ph value of the external aqueous phase equal to 5.0.

  10. Smart membranes for monitoring membrane based desalination processes

    KAUST Repository

    Laleg-Kirati, Taous-Meriem; Karam, Ayman M.

    2017-01-01

    Various examples are related to smart membranes for monitoring membrane based process such as, e.g., membrane distillation processes. In one example, a membrane, includes a porous surface and a plurality of sensors (e.g., temperature, flow and

  11. Membrane fusion-competent virus-like proteoliposomes and proteinaceous supported bilayers made directly from cell plasma membranes.

    Science.gov (United States)

    Costello, Deirdre A; Hsia, Chih-Yun; Millet, Jean K; Porri, Teresa; Daniel, Susan

    2013-05-28

    Virus-like particles are useful materials for studying virus-host interactions in a safe manner. However, the standard production of pseudovirus based on the vesicular stomatitis virus (VSV) backbone is an intricate procedure that requires trained laboratory personnel. In this work, a new strategy for creating virus-like proteoliposomes (VLPLs) and virus-like supported bilayers (VLSBs) is presented. This strategy uses a cell blebbing technique to induce the formation of nanoscale vesicles from the plasma membrane of BHK cells expressing the hemagglutinin (HA) fusion protein of influenza X-31. These vesicles and supported bilayers contain HA and are used to carry out single particle membrane fusion events, monitored using total internal reflection fluorescence microscopy. The results of these studies show that the VLPLs and VLSBs contain HA proteins that are fully competent to carry out membrane fusion, including the formation of a fusion pore and the release of fluorophores loaded into vesicles. This new strategy for creating spherical and planar geometry virus-like membranes has many potential applications. VLPLs could be used to study fusion proteins of virulent viruses in a safe manner, or they could be used as therapeutic delivery particles to transport beneficial proteins coexpressed in the cells to a target cell. VLSBs could facilitate high throughput screening of antiviral drugs or pathogen-host cell interactions.

  12. In-plane resolved in-situ measurements of the membrane resistance in PEFCs

    Energy Technology Data Exchange (ETDEWEB)

    Buechi, F N; Scherer, G G [Paul Scherrer Inst. (PSI), Villigen (Switzerland)

    1999-08-01

    The conductivity of the membrane is a limiting factor for the efficiency and power density of PEFCs. Because this conductivity is strongly dependent on the membrane hydration, water management is an important aspect of PEFC optimisation. Single cell model experiments were made in order to determine the in-plane hydration of a Nafion{sup R} membrane under fuel cell conditions as function of the gas humidities. (author) 4 fig., 3 refs.

  13. Biomimetic membranes and methods of making biomimetic membranes

    Science.gov (United States)

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

    2016-11-08

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

  14. Mesoporous Silica Gel-Based Mixed Matrix Membranes for Improving Mass Transfer in Forward Osmosis: Effect of Pore Size of Filler.

    Science.gov (United States)

    Lee, Jian-Yuan; Wang, Yining; Tang, Chuyang Y; Huo, Fengwei

    2015-11-23

    The efficiency of forward osmosis (FO) process is generally limited by the internal concentration polarization (ICP) of solutes inside its porous substrate. In this study, mesoporous silica gel (SG) with nominal pore size ranging from 4-30 nm was used as fillers to prepare SG-based mixed matrix substrates. The resulting mixed matrix membranes had significantly reduced structural parameter and enhanced membrane water permeability as a result of the improved surface porosity of the substrates. An optimal filler pore size of ~9 nm was observed. This is in direct contrast to the case of thin film nanocomposite membranes, where microporous nanoparticle fillers are loaded to the membrane rejection layer and are designed in such a way that these fillers are able to retain solutes while allowing water to permeate through them. In the current study, the mesoporous fillers are designed as channels to both water and solute molecules. FO performance was enhanced at increasing filler pore size up to 9 nm due to the lower hydraulic resistance of the fillers. Nevertheless, further increasing filler pore size to 30 nm was accompanied with reduced FO efficiency, which can be attributed to the intrusion of polymer dope into the filler pores.

  15. Mesoporous Silica Gel–Based Mixed Matrix Membranes for Improving Mass Transfer in Forward Osmosis: Effect of Pore Size of Filler

    Science.gov (United States)

    Lee, Jian-Yuan; Wang, Yining; Tang, Chuyang Y.; Huo, Fengwei

    2015-01-01

    The efficiency of forward osmosis (FO) process is generally limited by the internal concentration polarization (ICP) of solutes inside its porous substrate. In this study, mesoporous silica gel (SG) with nominal pore size ranging from 4–30 nm was used as fillers to prepare SG-based mixed matrix substrates. The resulting mixed matrix membranes had significantly reduced structural parameter and enhanced membrane water permeability as a result of the improved surface porosity of the substrates. An optimal filler pore size of ~9 nm was observed. This is in direct contrast to the case of thin film nanocomposite membranes, where microporous nanoparticle fillers are loaded to the membrane rejection layer and are designed in such a way that these fillers are able to retain solutes while allowing water to permeate through them. In the current study, the mesoporous fillers are designed as channels to both water and solute molecules. FO performance was enhanced at increasing filler pore size up to 9 nm due to the lower hydraulic resistance of the fillers. Nevertheless, further increasing filler pore size to 30 nm was accompanied with reduced FO efficiency, which can be attributed to the intrusion of polymer dope into the filler pores. PMID:26592565

  16. Internal structure of magnetic endosomes

    Science.gov (United States)

    Rivière, C.; Wilhelm, C.; Cousin, F.; Dupuis, V.; Gazeau, F.; Perzynski, R.

    2007-01-01

    The internal structure of biological vesicles filled with magnetic nanoparticles is investigated using the following complementary analyses: electronic transmission microscopy, dynamic probing by magneto-optical birefringence and structural probing by Small Angle Neutron Scattering (SANS). These magnetic vesicles are magnetic endosomes obtained via a non-specific interaction between cells and anionic magnetic iron oxide nanoparticles. Thanks to a magnetic purification process, they are probed at two different stages of their formation within HeLa cells: (i) adsorption of nanoparticles onto the cellular membrane and (ii) their subsequent internalisation within endosomes. Differences in the microenvironment of the magnetic nanoparticles at those two different stages are highlighted here. The dynamics of magnetic nanoparticles adsorbed onto cellular membranes and confined within endosomes is respectively 3 and 5 orders of magnitude slower than for isolated magnetic nanoparticles in aqueous media. Interestingly, SANS experiments show that magnetic endosomes have an internal structure close to decorated vesicles, with magnetic nanoparticles locally decorating the endosome membrane, inside their inner-sphere. These results, important for future biomedical applications, suggest that multiple fusions of decorated vesicles are the biological processes underlying the endocytosis of that kind of nanometric materials.

  17. Neutrons and model membranes

    Science.gov (United States)

    Fragneto, G.

    2012-11-01

    Current research in membrane protein biophysics highlights the emerging role of lipids in shaping membrane protein function. Cells and organisms have developed sophisticated mechanisms for controlling the lipid composition and many diseases are related to the failure of these mechanisms. One of the recent advances in the field is the discovery of the existence of coexisting micro-domains within a single membrane, important for regulating some signaling pathways. Many important properties of these domains remain poorly characterized. The characterization and analysis of bio-interfaces represent a challenge. Performing measurements on these few nanometer thick, soft, visco-elastic and dynamic systems is close to the limits of the available tools and methods. Neutron scattering techniques including small angle scattering, diffraction, reflectometry as well as inelastic methods are rapidly developing for these studies and are attracting an increasing number of biologists and biophysicists at large facilities. This manuscript will review some recent progress in the field and provide perspectives for future developments. It aims at highlighting neutron reflectometry as a versatile method to tackle questions dealing with the understanding and function of biomembranes and their components. The other important scattering methods are only briefly introduced.

  18. 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

  19. Single Molecule Kinetics of ENTH Binding to Lipid Membranes

    Energy Technology Data Exchange (ETDEWEB)

    Rozovsky, Sharon [Univ. of Delaware, Newark, DE (United States); Forstner, Martin B. [Syracuse Univ., NY (United States); Sondermann, Holger [Cornell Univ., Ithaca, NY (United States); Groves, Jay T. [Univ. of California, Berkeley, CA (United States); Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)

    2012-04-03

    Transient recruitment of proteins to membranes is a fundamental mechanism by which the cell exerts spatial and temporal control over proteins’ localization and interactions. Thus, the specificity and the kinetics of peripheral proteins’ membrane residence are an attribute of their function. In this article, we describe the membrane interactions of the interfacial epsin N-terminal homology (ENTH) domain with its target lipid phosphatidylinositol (4,5)-bisphosphate (PtdIns(4,5)P2). The direct visualization and quantification of interactions of single ENTH molecules with supported lipid bilayers is achieved using total internal reflection fluorescence microscopy (TIRFM) with a time resolution of 13 ms. This enables the recording of the kinetic behavior of ENTH interacting with membranes with physiologically relevant concentrations of PtdIns(4,5)P2 despite the low effective binding affinity. Subsequent single fluorophore tracking permits us to build up distributions of residence times and to measure ENTH dissociation rates as a function of membrane composition. In addition, due to the high time resolution, we are able to resolve details of the motion of ENTH associated with a simple, homogeneous membrane. In this case ENTH’s diffusive transport appears to be the result of at least three different diffusion processes.

  20. Cooperative tumour cell membrane targeted phototherapy

    Science.gov (United States)

    Kim, Heegon; Lee, Junsung; Oh, Chanhee; Park, Ji-Ho

    2017-06-01

    The targeted delivery of therapeutics using antibodies or nanomaterials has improved the precision and safety of cancer therapy. However, the paucity and heterogeneity of identified molecular targets within tumours have resulted in poor and uneven distribution of targeted agents, thus compromising treatment outcomes. Here, we construct a cooperative targeting system in which synthetic and biological nanocomponents participate together in the tumour cell membrane-selective localization of synthetic receptor-lipid conjugates (SR-lipids) to amplify the subsequent targeting of therapeutics. The SR-lipids are first delivered selectively to tumour cell membranes in the perivascular region using fusogenic liposomes. By hitchhiking with extracellular vesicles secreted by the cells, the SR-lipids are transferred to neighbouring cells and further spread throughout the tumour tissues where the molecular targets are limited. We show that this tumour cell membrane-targeted delivery of SR-lipids leads to uniform distribution and enhanced phototherapeutic efficacy of the targeted photosensitizer.

  1. Nanodisc-solubilized membrane protein library reflects the membrane proteome.

    Science.gov (United States)

    Marty, Michael T; Wilcox, Kyle C; Klein, William L; Sligar, Stephen G

    2013-05-01

    The isolation and identification of unknown membrane proteins offers the prospect of discovering new pharmaceutical targets and identifying key biochemical receptors. However, interactions between membrane protein targets and soluble ligands are difficult to study in vitro due to the insolubility of membrane proteins in non-detergent systems. Nanodiscs, nanoscale discoidal lipid bilayers encircled by a membrane scaffold protein belt, have proven to be an effective platform to solubilize membrane proteins and have been used to study a wide variety of purified membrane proteins. This report details the incorporation of an unbiased population of membrane proteins from Escherichia coli membranes into Nanodiscs. This solubilized membrane protein library (SMPL) forms a soluble in vitro model of the membrane proteome. Since Nanodiscs contain isolated proteins or small complexes, the SMPL is an ideal platform for interactomics studies and pull-down assays of membrane proteins. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis analysis of the protein population before and after formation of the Nanodisc library indicates that a large percentage of the proteins are incorporated into the library. Proteomic identification of several prominent bands demonstrates the successful incorporation of outer and inner membrane proteins into the Nanodisc library.

  2. Generation of membrane potential beyond the conceptual range of Donnan theory and Goldman-Hodgkin-Katz equation.

    Science.gov (United States)

    Tamagawa, Hirohisa; Ikeda, Kota

    2017-09-01

    Donnan theory and Goldman-Hodgkin-Katz equation (GHK eq.) state that the nonzero membrane potential is generated by the asymmetric ion distribution between two solutions separated by a semipermeable membrane and/or by the continuous ion transport across the semipermeable membrane. However, there have been a number of reports of the membrane potential generation behaviors in conflict with those theories. The authors of this paper performed the experimental and theoretical investigation of membrane potential and found that (1) Donnan theory is valid only when the macroscopic electroneutrality is sufficed and (2) Potential behavior across a certain type of membrane appears to be inexplicable on the concept of GHK eq. Consequently, the authors derived a conclusion that the existing theories have some limitations for predicting the membrane potential behavior and we need to find a theory to overcome those limitations. The authors suggest that the ion adsorption theory named Ling's adsorption theory, which attributes the membrane potential generation to the mobile ion adsorption onto the adsorption sites, could overcome those problems.

  3. Isolation and characterization of the plasma membrane from the yeast Pichia pastoris.

    Science.gov (United States)

    Grillitsch, Karlheinz; Tarazona, Pablo; Klug, Lisa; Wriessnegger, Tamara; Zellnig, Günther; Leitner, Erich; Feussner, Ivo; Daum, Günther

    2014-07-01

    Despite similarities of cellular membranes in all eukaryotes, every compartment displays characteristic and often unique features which are important for the functions of the specific organelles. In the present study, we biochemically characterized the plasma membrane of the methylotrophic yeast Pichia pastoris with emphasis on the lipids which form the matrix of this compartment. Prerequisite for this effort was the design of a standardized and reliable isolation protocol of the plasma membrane at high purity. Analysis of isolated plasma membrane samples from P. pastoris revealed an increase of phosphatidylserine and a decrease of phosphatidylcholine compared to bulk membranes. The amount of saturated fatty acids in the plasma membrane was higher than in total cell extracts. Ergosterol, the final product of the yeast sterol biosynthetic pathway, was found to be enriched in plasma membrane fractions, although markedly lower than in Saccharomyces cerevisiae. A further characteristic feature of the plasma membrane from P. pastoris was the enrichment of inositol phosphorylceramides over neutral sphingolipids, which accumulated in internal membranes. The detailed analysis of the P. pastoris plasma membrane is discussed in the light of cell biological features of this microorganism especially as a microbial cell factory for heterologous protein production. Copyright © 2014 Elsevier B.V. All rights reserved.

  4. Engineering plant membranes using droplet interface bilayers.

    Science.gov (United States)

    Barlow, N E; Smpokou, E; Friddin, M S; Macey, R; Gould, I R; Turnbull, C; Flemming, A J; Brooks, N J; Ces, O; Barter, L M C

    2017-03-01

    Droplet interface bilayers (DIBs) have become widely recognised as a robust platform for constructing model membranes and are emerging as a key technology for the bottom-up assembly of synthetic cell-like and tissue-like structures. DIBs are formed when lipid-monolayer coated water droplets are brought together inside a well of oil, which is excluded from the interface as the DIB forms. The unique features of the system, compared to traditional approaches (e.g., supported lipid bilayers, black lipid membranes, and liposomes), is the ability to engineer multi-layered bilayer networks by connecting multiple droplets together in 3D, and the capability to impart bilayer asymmetry freely within these droplet architectures by supplying droplets with different lipids. Yet despite these achievements, one potential limitation of the technology is that DIBs formed from biologically relevant components have not been well studied. This could limit the reach of the platform to biological systems where bilayer composition and asymmetry are understood to play a key role. Herein, we address this issue by reporting the assembly of asymmetric DIBs designed to replicate the plasma membrane compositions of three different plant species; Arabidopsis thaliana , tobacco, and oats, by engineering vesicles with different amounts of plant phospholipids, sterols and cerebrosides for the first time. We show that vesicles made from our plant lipid formulations are stable and can be used to assemble asymmetric plant DIBs. We verify this using a bilayer permeation assay, from which we extract values for absolute effective bilayer permeation and bilayer stability. Our results confirm that stable DIBs can be assembled from our plant membrane mimics and could lead to new approaches for assembling model systems to study membrane translocation and to screen new agrochemicals in plants.

  5. Transferable, conductive TiO{sub 2} nanotube membranes for optoelectronics

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Guohua [School of Energy and Environment, Anhui University of Technology, Maanshan 243002 (China); Department of Micro and Nano Systems Technology, Vestfold University College, Horten 3184 (Norway); Chen, Ting [School of Chemistry and Chemical Engineering, Sun Yat-Sen University, Guangzhou 510275 (China); Sun, Yunlan; Chen, Guang [School of Energy and Environment, Anhui University of Technology, Maanshan 243002 (China); Wang, Kaiying, E-mail: Kaiying.Wang@hbv.no [Department of Micro and Nano Systems Technology, Vestfold University College, Horten 3184 (Norway)

    2014-08-30

    Graphical abstract: An optoelectronic device with vertical architecture offers straight conducting filaments for electron transportation. - Highlights: • Highly porous TiO{sub 2} nanotube membranes are prepared by two-step anodization. • An optoelectronic device is integrated with photocurrent transportation along the nanotube axial. • Straight conducting nano-filaments are beneficial for electron transportation. • Photoconductive performances are demonstrated under front/back-illumination. - Abstract: We report a facile approach for preparing free-standing and crystalline TiO{sub 2} nanotube membranes (TNMs) by taking advantage of differential mechanical stress between two anodic layers. The membrane exhibits visible light transmittance (∼40%) and UV absorption (∼99%) with good flexibility, which is favorable to integrate with substrates in optoelectronics. A sandwich-type device is assembled through stacking the membrane and substrates. The dependence of current-perpendicular-to-membrane vs applied voltage shows a remarkable photoconductive performance for both front and back illumination. The photocurrent value increases ∼2 or 3 orders magnitude under UV light radiation as compared to that in darkness. The photoresponse is arisen from high internal gain caused by hole trapping along the nanotube walls. This work is crucial for understanding intrinsic optical properties of nanostructured membranes.

  6. Assessments of lysosomal membrane responses to stresses with ...

    African Journals Online (AJOL)

    In marine bivalves, it has been demonstrated that their lysosomal membrane stability are very susceptible to many internal and external environmental changes and this physiological response can be quantified by the neutral red retention (NRR) assay. This assay has been applied in many recent studies in the areas of ...

  7. Pressure retarded osmosis for energy production: membrane materials and operating conditions.

    Science.gov (United States)

    Kim, H; Choi, J-S; Lee, S

    2012-01-01

    Pressure retarded osmosis (PRO) is a novel membrane process to produce energy. PRO has the potential to convert the osmotic pressure difference between fresh water (i.e. river water) and seawater to electricity. Moreover, it can recover energy from highly concentrated brine in seawater desalination. Nevertheless, relatively little research has been undertaken for fundamental understanding of the PRO process. In this study, the characteristics of the PRO process were examined using a proof-of-concept device. Forward osmosis (FO), reverse osmosis (RO), and nanofiltration (NF) membranes were compared in terms of flux rate and concentration polarization ratio. The results indicated that the theoretical energy production by PRO depends on the membrane type as well as operating conditions (i.e. back pressure). The FO membrane had the highest energy efficiency while the NF membrane had the lowest efficiency. However, the energy production rate was low due to high internal concentration polarization (ICP) in the PRO membrane. This finding suggests that the control of the ICP is essential for practical application of PRO for energy production.

  8. Enhanced sensitivity of a microfabricated resonator using a graphene-polystyrene bilayer membrane

    Energy Technology Data Exchange (ETDEWEB)

    Yun, Minhyuk; Lee, Eunho; Cho, Kilwon; Jeon, Sangmin, E-mail: jeons@postech.ac.kr [Department of Chemical Engineering, Pohang University of Science and Technology (POSTECH), Pohang (Korea, Republic of)

    2014-08-18

    A graphene layer was synthesized using chemical vapor deposition methods and a polystyrene solution was spin-cast onto the graphene film. The graphene-polystyrene bilayer membrane was attached between the two tines of a microfabricated quartz tuning fork (QTF). The modulus of the graphene-polystyrene bilayer was measured to be twice that of a pristine polystyrene membrane. Exposure of the membrane-coated QTF to ethanol vapor decreased the resonance frequency of the microresonator. The bilayer membrane-coated QTF produced a frequency change that was three times the change obtained using a polystyrene membrane-coated QTF, with a lower degree of degradation in the Q factor. The limit of detection of the bilayer membrane-coated QTF to ethanol vapor was determined to be 20 ppm.

  9. 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.

  10. Evidence that membrane transduction of oligoarginine does not require vesicle formation

    International Nuclear Information System (INIS)

    Zaro, Jennica L.; Shen Weichiang

    2005-01-01

    The involvement of vesicular formation processes in the membrane transduction and nuclear transport of oligoarginine is currently a subject of controversy. In this report, a novel quantitative method which allows for the selective measurement of membrane transduction excluding concurrent endocytosis was used to determine the effects of temperature, endosomal acidification, endosomolysis, and several known inhibitors of endocytic pathways on the internalization of oligoarginine. The results show that, unlike endocytosis, transduction of oligoarginine was not affected by incubation at 16 deg. C as compared to the 37 deg. C control, and was only partially inhibited at 4 deg. C incubation. Additionally, membrane transduction was not inhibited to the same extent as endocytosis following treatment with ammonium chloride, hypertonic medium, amiloride, or filipin. The endosomolytic activity of oligoarginine was investigated by examining the leakage of FITC-dextran into the cytosolic compartment, which was not higher in the presence of oligoarginine. Furthermore, ammonium chloride showed no effect on the nuclear transport of oligoarginine. The data presented in this report indicate that membrane transduction is likely to occur at the plasma membrane without the formation of membrane vesicles, and the nuclear localization involves membrane transduction, rather than endocytosis of oligoarginine

  11. Hydraulically irreversible fouling on ceramic MF/UF membranes: comparison of fouling indices, foulant composition and irreversible pore narrowing

    KAUST Repository

    Shang, Ran; Vuong, Francois; Hu, Jingyi; Li, Sheng; Kemperman, Antoine J.B.; Nijmeijer, Kitty; Cornelissen, Emile R.; Heijman, Sebastiaan G.J.; Rietveld, Luuk C.

    2015-01-01

    The application of ceramic membranes in water treatment is becoming increasing attractive because of their long life time and excellent chemical, mechanical and thermal stability. However, fouling of ceramic membranes, especially hydraulically irreversible fouling, is still a critical aspect affecting the operational cost and energy consumption in water treatment plants. In this study, four ceramic membranes with pore sizes or molecular weight cut-off (MWCO) of 0.20 μm, 0.14 μm, 300 kDa and 50 kDa were compared during natural surface water filtration with respect to hydraulically irreversible fouling index (HIFI), foulant composition and narrowing of pore size due to the irreversible fouling. Our results showed that the hydraulically irreversible fouling index (HIFI) was proportional to the membrane pore size (r2=0.89) when the same feed water was filtrated. The UF membranes showed lower HIFI values than the MF membranes. Pore narrowing (internal fouling) was found to be a main fouling pattern of the hydraulically irreversible fouling. The internal fouling was caused by monolayer adsorption of foulants with different sizes that is dependent on the size of the membrane pore.

  12. Hydraulically irreversible fouling on ceramic MF/UF membranes: comparison of fouling indices, foulant composition and irreversible pore narrowing

    KAUST Repository

    Shang, Ran

    2015-05-06

    The application of ceramic membranes in water treatment is becoming increasing attractive because of their long life time and excellent chemical, mechanical and thermal stability. However, fouling of ceramic membranes, especially hydraulically irreversible fouling, is still a critical aspect affecting the operational cost and energy consumption in water treatment plants. In this study, four ceramic membranes with pore sizes or molecular weight cut-off (MWCO) of 0.20 μm, 0.14 μm, 300 kDa and 50 kDa were compared during natural surface water filtration with respect to hydraulically irreversible fouling index (HIFI), foulant composition and narrowing of pore size due to the irreversible fouling. Our results showed that the hydraulically irreversible fouling index (HIFI) was proportional to the membrane pore size (r2=0.89) when the same feed water was filtrated. The UF membranes showed lower HIFI values than the MF membranes. Pore narrowing (internal fouling) was found to be a main fouling pattern of the hydraulically irreversible fouling. The internal fouling was caused by monolayer adsorption of foulants with different sizes that is dependent on the size of the membrane pore.

  13. Surface modification of titanium membrane by chemical vapor deposition and its electrochemical self-cleaning

    Energy Technology Data Exchange (ETDEWEB)

    Li, X.W., E-mail: lynnww@sohu.com [School of Electronic and Information Engieering, Tianjin university, Tianjin, 300072 (China); School of Electronics Information Engieering, Tianjin University of Technology, Tianjin, 300384 (China); Li, J.X. [Tianjin Polytechnic University, Tianjin 300160 (China); Gao, C.Y. [Chinese Peoples Armed Police Forces Academy, Langfang 065000 (China); Chang, M. [School of Electronic and Information Engieering, Tianjin university, Tianjin, 300072 (China); School of Electronics Information Engieering, Tianjin University of Technology, Tianjin, 300384 (China)

    2011-10-15

    Membrane separation is applied widely in many fields, while concentration polarization and membrane fouling, limiting its promotion and application greatly, are the bottlenecks in membrane application. Among which, membrane fouling is irreversible, membrane must be periodically cleaned or even replaced to restore permeability. Membrane cleaning has become one of Key issues in membrane separation areas. Considering incomparable electrochemical advantages of boron-doped diamond (BDD) film electrode over conventional electrode, a new composite membrane Ti/BDD, made by depositing CVD (chemical vapor deposition) boron-doped diamond film on titanium(Ti) membrane to modify porous titanium surface, that can be cleaned electrochemically is proposed. Feasibility of its preparation and application is discussed in this paper. Results shows that based on the unique electrochemical properties of diamond, cleaning level of this composite Ti/BDD membrane is significantly increased, making membrane life and efficiency improved prominently.

  14. Surface modification of titanium membrane by chemical vapor deposition and its electrochemical self-cleaning

    International Nuclear Information System (INIS)

    Li, X.W.; Li, J.X.; Gao, C.Y.; Chang, M.

    2011-01-01

    Membrane separation is applied widely in many fields, while concentration polarization and membrane fouling, limiting its promotion and application greatly, are the bottlenecks in membrane application. Among which, membrane fouling is irreversible, membrane must be periodically cleaned or even replaced to restore permeability. Membrane cleaning has become one of Key issues in membrane separation areas. Considering incomparable electrochemical advantages of boron-doped diamond (BDD) film electrode over conventional electrode, a new composite membrane Ti/BDD, made by depositing CVD (chemical vapor deposition) boron-doped diamond film on titanium(Ti) membrane to modify porous titanium surface, that can be cleaned electrochemically is proposed. Feasibility of its preparation and application is discussed in this paper. Results shows that based on the unique electrochemical properties of diamond, cleaning level of this composite Ti/BDD membrane is significantly increased, making membrane life and efficiency improved prominently.

  15. 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.

  16. An Integrated Framework Advancing Membrane Protein Modeling and Design.

    Directory of Open Access Journals (Sweden)

    Rebecca F Alford

    2015-09-01

    Full Text Available Membrane proteins are critical functional molecules in the human body, constituting more than 30% of open reading frames in the human genome. Unfortunately, a myriad of difficulties in overexpression and reconstitution into membrane mimetics severely limit our ability to determine their structures. Computational tools are therefore instrumental to membrane protein structure prediction, consequently increasing our understanding of membrane protein function and their role in disease. Here, we describe a general framework facilitating membrane protein modeling and design that combines the scientific principles for membrane protein modeling with the flexible software architecture of Rosetta3. This new framework, called RosettaMP, provides a general membrane representation that interfaces with scoring, conformational sampling, and mutation routines that can be easily combined to create new protocols. To demonstrate the capabilities of this implementation, we developed four proof-of-concept applications for (1 prediction of free energy changes upon mutation; (2 high-resolution structural refinement; (3 protein-protein docking; and (4 assembly of symmetric protein complexes, all in the membrane environment. Preliminary data show that these algorithms can produce meaningful scores and structures. The data also suggest needed improvements to both sampling routines and score functions. Importantly, the applications collectively demonstrate the potential of combining the flexible nature of RosettaMP with the power of Rosetta algorithms to facilitate membrane protein modeling and design.

  17. Fluorescent probes for detecting cholesterol-rich ordered membrane microdomains: entangled relationships between structural analogies in the membrane and functional homologies in the cell

    Directory of Open Access Journals (Sweden)

    Gérald Gaibelet

    2017-02-01

    Full Text Available This review addresses the question of fluorescent detection of ordered membrane (micro domains in living (cultured cells, with a “practical” point of view since the situation is much more complicated than for studying model membranes. We first briefly recall the bases of model membrane structural organization involving liquid-ordered and -disordered phases, and the main features of their counterparts in cell membranes that are the various microdomains. We then emphasize the utility of the fluorescent probes derived from cholesterol, and delineate the respective advantages, limitations and drawbacks of the existing ones. In particular, besides their intra-membrane behavior, their relevant characteristics should integrate their different cellular fates for membrane turn-over, trafficking and metabolism, in order to evaluate and improve their efficiency for in-situ probing membrane microdomains in the cell physiology context. Finally, at the present stage, it appears that Bdp-Chol and Pyr-met-Chol display well complementary properties, allowing to use them in combination to improve the reliability of the current experimental approaches. But the field is still open, and there remains much work to perform in this research area.

  18. Higher boron rejection with a new TFC forward osmosis membrane

    KAUST Repository

    Valladares Linares, Rodrigo; Li, Zhenyu; Sarp, Sarper; Park, Y. G.; Amy, Gary L.; Vrouwenvelder, Johannes S.

    2014-01-01

    Due to the stringent limits for boron in drinking and irrigation water, water treatment facilities have to incur additional treatment to remove boron down to a safe concentration. Forward osmosis (FO) is a membrane technology that may reduce the energy required to remove boron present in seawater. In direct FO desalination hybrid systems, fresh water is recovered from seawater using a recoverable draw solution, FO membranes are expected to show high boron rejection. This study focuses on determining the boron rejection capabilities of a new generation thin-film composite (TFC) FO membrane compared to a first generation cellulose triacetate (CTA) FO membrane. The effects of water permeate flux, membrane structure, draw solute charge, and reverse solute flux on boron rejection were determined. For TFC and CTA FO membranes, experiments showed that when similar operating conditions are applied (e.g. membrane type and draw solute type) boron rejection decreases with increase in permeate flux. Reverse draw solute flux and membrane fouling have no significant impact on boron rejection. Compared to the first generation CTA FO membrane operated at the same conditions, the TFC FO membrane showed a 40% higher boron rejection capability and a 20% higher water flux. This demonstrates the potential for boron removal for new generation TFC FO membranes. © 2014 © 2014 Balaban Desalination Publications. All rights reserved.

  19. Higher boron rejection with a new TFC forward osmosis membrane

    KAUST Repository

    Valladares Linares, Rodrigo

    2014-07-17

    Due to the stringent limits for boron in drinking and irrigation water, water treatment facilities have to incur additional treatment to remove boron down to a safe concentration. Forward osmosis (FO) is a membrane technology that may reduce the energy required to remove boron present in seawater. In direct FO desalination hybrid systems, fresh water is recovered from seawater using a recoverable draw solution, FO membranes are expected to show high boron rejection. This study focuses on determining the boron rejection capabilities of a new generation thin-film composite (TFC) FO membrane compared to a first generation cellulose triacetate (CTA) FO membrane. The effects of water permeate flux, membrane structure, draw solute charge, and reverse solute flux on boron rejection were determined. For TFC and CTA FO membranes, experiments showed that when similar operating conditions are applied (e.g. membrane type and draw solute type) boron rejection decreases with increase in permeate flux. Reverse draw solute flux and membrane fouling have no significant impact on boron rejection. Compared to the first generation CTA FO membrane operated at the same conditions, the TFC FO membrane showed a 40% higher boron rejection capability and a 20% higher water flux. This demonstrates the potential for boron removal for new generation TFC FO membranes. © 2014 © 2014 Balaban Desalination Publications. All rights reserved.

  20. Alternative energy efficient membrane bioreactor using reciprocating submerged membrane.

    Science.gov (United States)

    Ho, J; Smith, S; Roh, H K

    2014-01-01

    A novel membrane bioreactor (MBR) pilot system, using membrane reciprocation instead of air scouring, was operated at constant high flux and daily fluctuating flux to demonstrate its application under peak and diurnal flow conditions. Low and stable transmembrane pressure was achieved at 40 l/m(2)/h (LMH) by use of repetitive membrane reciprocation. The results reveal that the inertial forces acting on the membrane fibers effectively propel foulants from the membrane surface. Reciprocation of the hollow fiber membrane is beneficial for the constant removal of solids that may build up on the membrane surface and inside the membrane bundle. The membrane reciprocation in the reciprocating MBR pilot consumed less energy than coarse air scouring used in conventional MBR systems. Specific energy consumption for the membrane reciprocation was 0.072 kWh/m(3) permeate produced at 40 LMH flux, which is 75% less than for a conventional air scouring system as reported in literature without consideration of energy consumption for biological aeration (0.29 kWh/m(3)). The daily fluctuating flux test confirmed that the membrane reciprocation is effective to handle fluctuating flux up to 50 LMH. The pilot-scale reciprocating MBR system successfully demonstrated that fouling can be controlled via 0.43 Hz membrane reciprocation with 44 mm or higher amplitude.

  1. 26 CFR 1.851-2 - Limitations.

    Science.gov (United States)

    2010-04-01

    ... 26 Internal Revenue 9 2010-04-01 2010-04-01 false Limitations. 1.851-2 Section 1.851-2 Internal Revenue INTERNAL REVENUE SERVICE, DEPARTMENT OF THE TREASURY (CONTINUED) INCOME TAX (CONTINUED) INCOME TAXES Regulated Investment Companies and Real Estate Investment Trusts § 1.851-2 Limitations. (a...

  2. The dynamics of plant plasma membrane proteins: PINs and beyond.

    Science.gov (United States)

    Luschnig, Christian; Vert, Grégory

    2014-08-01

    Plants are permanently situated in a fixed location and thus are well adapted to sense and respond to environmental stimuli and developmental cues. At the cellular level, several of these responses require delicate adjustments that affect the activity and steady-state levels of plasma membrane proteins. These adjustments involve both vesicular transport to the plasma membrane and protein internalization via endocytic sorting. A substantial part of our current knowledge of plant plasma membrane protein sorting is based on studies of PIN-FORMED (PIN) auxin transport proteins, which are found at distinct plasma membrane domains and have been implicated in directional efflux of the plant hormone auxin. Here, we discuss the mechanisms involved in establishing such polar protein distributions, focusing on PINs and other key plant plasma membrane proteins, and we highlight the pathways that allow for dynamic adjustments in protein distribution and turnover, which together constitute a versatile framework that underlies the remarkable capabilities of plants to adjust growth and development in their ever-changing environment. © 2014. Published by The Company of Biologists Ltd.

  3. Dual phase oxygen transport membrane for efficient oxyfuel combustion

    Energy Technology Data Exchange (ETDEWEB)

    Ramasamy, Madhumidha

    2016-07-01

    Oxygen transport membranes (OTMs) are attracting great interest for the separation of oxygen from air in an energy efficient way. A variety of solid oxide ceramic materials that possess mixed ionic and electronic conductivity (MIEC) are being investigated for efficient oxygen separation (Betz '10, Skinner '03). Unfortunately these materials do not exhibit high degradation stability under harsh ambient conditions such as flue gas containing CO{sub 2}, SO{sub x}, H{sub 2}O and dust, pressure gradients and high temperatures that are typical in fossil fuel power plants. For this reason, dual phase composite membranes are developed to combine the best characteristics of different compounds to achieve high oxygen permeability and sufficient chemical and mechanical stability at elevated temperatures. In this thesis, the dual phase membrane Ce{sub 0.8}Gd{sub 0.2}O{sub 2-δ} - FeCo{sub 2}O{sub 4} (CGO-FCO) was developed after systematic investigation of various combinations of ionic and electronic conductors. The phase distribution of the composite was investigated in detail using electron microscopes and this analysis revealed the phase interaction leading to grain boundary rock salt phase and formation of perovskite secondary phase. A systematic study explored the onset of phase interactions to form perovskite phase and the role of this unintended phase as pure electronic conductor was identified. Additionally optimization of conventional sintering process to eliminate spinel phase decomposition into rock salt was identified. An elaborate study on the absolute minimum electronic conductor requirement for efficient percolation network was carried out and its influence on oxygen flux value was measured. Oxygen permeation measurements in the temperature range of 600 C - 1000 C under partial pressure gradient provided by air and argon as feed and sweep gases are used to identify limiting transport processes. The dual phase membranes are much more prone to surface

  4. Advanced Wastewater Treatment Engineering—Investigating Membrane Fouling in both Rotational and Static Membrane Bioreactor Systems Using Empirical Modelling

    Directory of Open Access Journals (Sweden)

    Parneet Paul

    2016-01-01

    Full Text Available Advanced wastewater treatment using membranes are popular environmental system processes since they allow reuse and recycling. However, fouling is a key limiting factor and so proprietary systems such as Avanti’s RPU-185 Flexidisks membrane bioreactor (MBR use novel rotating membranes to assist in ameliorating it. In earlier research, this rotating process was studied by creating a simulation model based on first principles and traditional fouling mechanisms. In order to directly compare the potential benefits of this rotational system, this follow-up study was carried out using Avanti’s newly developed static (non-rotating Flexidisks MBR system. The results from operating the static pilot unit were simulated and modelled using the rotational fouling model developed earlier however with rotational switching functions turned off and rotational parameters set to a static mode. The study concluded that a rotating MBR system could increase flux throughput when compared against a similar static system. It is thought that although the slowly rotating spindle induces a weak crossflow shear, it is still able to even out cake build up across the membrane surface, thus reducing the likelihood of localised critical flux being exceeded at the micro level and lessening the potential of rapid trans-membrane pressure increases at the macro level.

  5. Development of PVDF Membrane Nanocomposites via Various Functionalization Approaches for Environmental Applications

    Directory of Open Access Journals (Sweden)

    Douglas M. Davenport

    2016-01-01

    Full Text Available Membranes are finding wide applications in various fields spanning biological, water, and energy areas. Synthesis of membranes to provide tunable flux, metal sorption, and catalysis has been done through pore functionalization of microfiltration (MF type membranes with responsive behavior. This methodology provides an opportunity to improve synthetic membrane performance via polymer fabrication and surface modification. By optimizing the polymer coagulation conditions in phase inversion fabrication, spongy polyvinylidene fluoride (PVDF membranes with high porosity and large internal pore volume were created in lab and full scale. This robust membrane shows a promising mechanical strength as well as high capacity for loading of adsorptive and catalytic materials. By applying surface modification techniques, synthetic membranes with different functionality (carboxyl, amine, and nanoparticle-based were obtained. These functionalities provide an opportunity to fine-tune the membrane surface properties such as charge and reactivity. The incorporation of stimuli-responsive acrylic polymers (polyacrylic acid or sodium polyacrylate in membrane pores also results in tunable pore size and ion-exchange capacity. This provides the added benefits of adjustable membrane permeability and metal capture efficiency. The equilibrium and dynamic binding capacity of these functionalized spongy membranes were studied via calcium ion-exchange. Iron/palladium catalytic nanoparticles were immobilized in the polymer matrix in order to perform the challenging degradation of the environmental pollutant trichloroethylene (TCE.

  6. CROSS-FLOW ULTRAFILTRATION OF SECONDARY EFFLUENTS. MEMBRANE FOULING ANALYSIS

    Directory of Open Access Journals (Sweden)

    Luisa Vera

    2014-12-01

    Full Text Available The application of cross-flow ultrafiltration to regenerate secondary effluents is limited by membrane fouling. This work analyzes the influence of the main operational parameters (transmembrane pressure and cross-flow velocity about the selectivity and fouling observed in an ultrafiltration tubular ceramic membrane. The experimental results have shown a significant retention of the microcolloidal and soluble organic matter (52 – 54% in the membrane. The fouling analysis has defined the critical operational conditions where the fouling resistance is minimized. Such conditions can be described in terms of a dimensionless number known as shear stress number and its relationship with other dimensionless parameter, the fouling number.

  7. Tight ceramic UF membrane as RO pre-treatment: the role of electrostatic interactions on phosphate rejection.

    Science.gov (United States)

    Shang, Ran; Verliefde, Arne R D; Hu, Jingyi; Zeng, Zheyi; Lu, Jie; Kemperman, Antoine J B; Deng, Huiping; Nijmeijer, Kitty; Heijman, Sebastiaan G J; Rietveld, Luuk C

    2014-01-01

    Phosphate limitation has been reported as an effective approach to inhibit biofouling in reverse osmosis (RO) systems for water purification. The rejection of dissolved phosphate by negatively charged TiO2 tight ultrafiltration (UF) membranes (1 kDa and 3 kDa) was observed. These membranes can potentially be adopted as an effective process for RO pre-treatment in order to constrain biofouling by phosphate limitation. This paper focuses on electrostatic interactions during tight UF filtration. Despite the larger pore size, the 3 kDa ceramic membrane exhibited greater phosphate rejection than the 1 kDa membrane, because the 3 kDa membrane has a greater negative surface charge and thus greater electrostatic repulsion against phosphate. The increase of pH from 6 to 8.5 led to a substantial increase in phosphate rejection by both membranes due to increased electrostatic repulsion. At pH 8.5, the maximum phosphate rejections achieved by the 1 kDa and 3 kDa membrane were 75% and 86%, respectively. A Debye ratio (ratio of the Debye length to the pore radius) is introduced in order to evaluate double layer overlapping in tight UF membranes. Threshold Debye ratios were determined as 2 and 1 for the 1 kDa and 3 kDa membranes, respectively. A Debye ratio below the threshold Debye ratio leads to dramatically decreased phosphate rejection by tight UF membranes. The phosphate rejection by the tight UF, in combination with chemical phosphate removal by coagulation, might accomplish phosphate-limited conditions for biological growth and thus prevent biofouling in the RO systems. Copyright © 2013 Elsevier Ltd. All rights reserved.

  8. Quantifying pulsed electric field-induced membrane nanoporation in single cells.

    Science.gov (United States)

    Moen, Erick K; Ibey, Bennett L; Beier, Hope T; Armani, Andrea M

    2016-11-01

    Plasma membrane disruption can trigger a host of cellular activities. One commonly observed type of disruption is pore formation. Molecular dynamic (MD) simulations of simplified lipid membrane structures predict that controllably disrupting the membrane via nano-scale poration may be possible with nanosecond pulsed electric fields (nsPEF). Until recently, researchers hoping to verify this hypothesis experimentally have been limited to measuring the relatively slow process of fluorescent markers diffusing across the membrane, which is indirect evidence of nanoporation that could be channel-mediated. Leveraging recent advances in nonlinear optical microscopy, we elucidate the role of pulse parameters in nsPEF-induced membrane permeabilization in live cells. Unlike previous techniques, it is able to directly observe loss of membrane order at the onset of the pulse. We also develop a complementary theoretical model that relates increasing membrane permeabilization to membrane pore density. Due to the significantly improved spatial and temporal resolution possible with our imaging method, we are able to directly compare our experimental and theoretical results. Their agreement provides substantial evidence that nanoporation does occur and that its development is dictated by the electric field distribution. Copyright © 2016 Elsevier B.V. All rights reserved.

  9. Heavy trypan blue staining of epiretinal membranes: an alternative to infracyanine green

    NARCIS (Netherlands)

    Oberstein, Sarit Y. Lesnik; Mura, Marco; Tan, Stevie H.; de Smet, Marc D.

    2007-01-01

    BACKGROUND: By using dyes, it is easier to identify the extent of an epiretinal membrane (ERM) or the inner limiting membrane (ILM) during surgery. Trypan blue (TB) stains ERM and ILM weakly, but with less apparent toxicity than other intraocular dyes. Its main drawback in vitreoretinal surgery is

  10. Effect of Graphene and Fullerene Nanofillers on Controlling the Pore Size and Physicochemical Properties of Chitosan Nanocomposite Mesoporous Membranes

    Directory of Open Access Journals (Sweden)

    Irene S. Fahim

    2015-01-01

    Full Text Available Chitosan (CS nanocomposite mesoporous membranes were fabricated by mixing CS with graphene (G and fullerene (F nanofillers, and the diffusion properties through CS membranes were studied. In addition, in order to enhance the binding between the internal CS chains, physical cross-linking of CS by sodium tripolyphosphate (TPP was carried out. F and G with different weight percentages (0.1, 0.5, and 1 wt.% were added on physically cross-linked chitosan (CLCS and non-cross-linked chitosan (NCLCS membranes by wet mixing. Permeability and diffusion time of CLCS and NCLCS membranes at different temperatures were investigated. The results revealed that the pore size of all fabricated CS membranes is in the mesoporous range (i.e., 2–50 nm. Moreover, the addition of G and F nanofillers to CLCS and NCLCS solutions aided in controlling the CS membranes’ pore size and was found to enhance the barrier effect of the CS membranes either by blocking the internal pores or decreasing the pore size. These results illustrate the significant possibility of controlling the pore size of CS membranes by cross-linking and more importantly the careful selection of nanofillers and their percentage within the CS membranes. Controlling the pore size of CS membranes is a fundamental factor in packaging applications and membrane technology.

  11. Limitation of liability for maritime claims: Chronological critical review (international instruments and Croatian solutions

    Directory of Open Access Journals (Sweden)

    Vasilj Aleksandra V.

    2016-01-01

    Full Text Available Limitation of liability of shipowner can based on property or can be personal - shipowner responds to certain part of the property (for example ship or his entire assets to a certain amount. In the first case it is a real, and in the other the personal limitation of liability. On these principles all international instruments in this legal field have been developed. One of the well-known 'universal' principle of civil law says that the injurer must pay for a damage in full, in full extent and amount. However, when we are applying provisions of maritime law (as well as transport law in general on the liability for damages and its compensation, the situation is quite opposite. Though, that the amount of suffered damages is coming closer to said universal principle of civil law has been confirmed by Amendments to the Protocol to the Convention on Limitation of Liability for Maritime Claims 1996 (LLMC 1996. These Amendments increased amount of general (global limitation of liability for maritime claims by 51% compared to the amounts in LLMC. Increased amounts are applicable from 8th June 2015. Regarding these amendments, a number of issues can be placed: justification for introducing the institute of limitation of liability in general; reasons why the injurer is privileged in maritime (and broader in transport, in the context of the amount of the obligation of compensation for damage; and whether the application of the institute undermine the principle that is enshrined in the legal system of every modern country, according to which the injured party has the right to just compensation. On the other hand, justice can be taken as well as an argument just to implement the limitation of liability system.

  12. Microscopic hydrodynamics study with nuclear track membrane

    International Nuclear Information System (INIS)

    Shilun Guo; Yuhua Zhao; Yulan Wang; Hiuhong Hao; Brandt, R.; Vater, P.

    1988-01-01

    Microscopic hydrodynamics has been studied using different liquids and nuclear track membranes with pores perpendicularly piercing through them. The flow rate of water and alcohol has been studied with polycarbonate track membranes with pore diameters 1.48 micrometres and 1.08 micrometres. It has been shown that the flow rate both for water and alcohol on a microscopic scale can be determined by the Poiseuille law which characterizes macroscopic laminar flow. The Reynolds number used in macroscopic fluid flow has been calculated from the flow rate and parameters of the liquids and the geometry of the pores. It has been shown that this Reynolds number can also be used to characterize microscopic flow. Based on the above results, the filtration capacity (or limit) of polycarbonate track microfilters for water had been calculated. Some possible limits on the application of the calculation are pointed out and discussed. (author)

  13. 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.

  14. Empirical membrane lifetime model for heavy duty fuel cell systems

    Science.gov (United States)

    Macauley, Natalia; Watson, Mark; Lauritzen, Michael; Knights, Shanna; Wang, G. Gary; Kjeang, Erik

    2016-12-01

    Heavy duty fuel cells used in transportation system applications such as transit buses expose the fuel cell membranes to conditions that can lead to lifetime-limiting membrane failure via combined chemical and mechanical degradation. Highly durable membranes and reliable predictive models are therefore needed in order to achieve the ultimate heavy duty fuel cell lifetime target of 25,000 h. In the present work, an empirical membrane lifetime model was developed based on laboratory data from a suite of accelerated membrane durability tests. The model considers the effects of cell voltage, temperature, oxygen concentration, humidity cycling, humidity level, and platinum in the membrane using inverse power law and exponential relationships within the framework of a general log-linear Weibull life-stress statistical distribution. The obtained model is capable of extrapolating the membrane lifetime from accelerated test conditions to use level conditions during field operation. Based on typical conditions for the Whistler, British Columbia fuel cell transit bus fleet, the model predicts a stack lifetime of 17,500 h and a membrane leak initiation time of 9200 h. Validation performed with the aid of a field operated stack confirmed the initial goal of the model to predict membrane lifetime within 20% of the actual operating time.

  15. The homeodomain derived peptide Penetratin induces curvature of fluid membrane domains.

    Directory of Open Access Journals (Sweden)

    Antonin Lamazière

    Full Text Available BACKGROUND: Protein membrane transduction domains that are able to cross the plasma membrane are present in several transcription factors, such as the homeodomain proteins and the viral proteins such as Tat of HIV-1. Their discovery resulted in both new concepts on the cell communication during development, and the conception of cell penetrating peptide vectors for internalisation of active molecules into cells. A promising cell penetrating peptide is Penetratin, which crosses the cell membranes by a receptor and metabolic energy-independent mechanism. Recent works have claimed that Penetratin and similar peptides are internalized by endocytosis, but other endocytosis-independent mechanisms have been proposed. Endosomes or plasma membranes crossing mechanisms are not well understood. Previously, we have shown that basic peptides induce membrane invaginations suggesting a new mechanism for uptake, "physical endocytosis". METHODOLOGY/PRINCIPAL FINDINGS: Herein, we investigate the role of membrane lipid phases on Penetratin induced membrane deformations (liquid ordered such as in "raft" microdomains versus disordered fluid "non-raft" domains in membrane models. Experimental data show that zwitterionic lipid headgroups take part in the interaction with Penetratin suggesting that the external leaflet lipids of cells plasma membrane are competent for peptide interaction in the absence of net negative charges. NMR and X-ray diffraction data show that the membrane perturbations (tubulation and vesiculation are associated with an increase in membrane negative curvature. These effects on curvature were observed in the liquid disordered but not in the liquid ordered (raft-like membrane domains. CONCLUSIONS/SIGNIFICANCE: The better understanding of the internalisation mechanisms of protein transduction domains will help both the understanding of the mechanisms of cell communication and the development of potential therapeutic molecular vectors. Here we

  16. High resolution neutron imaging of water in the polymer electrolyte fuel cell membrane

    Energy Technology Data Exchange (ETDEWEB)

    Mukherjee, Partha P [Los Alamos National Laboratory; Makundan, Rangachary [Los Alamos National Laboratory; Spendelow, Jacob S [Los Alamos National Laboratory; Borup, Rodney L [Los Alamos National Laboratory; Hussey, D S [NIST; Jacobson, D L [NIST; Arif, M [NIST

    2009-01-01

    Water transport in the ionomeric membrane, typically Nafion{reg_sign}, has profound influence on the performance of the polymer electrolyte fuel cell, in terms of internal resistance and overall water balance. In this work, high resolution neutron imaging of the Nafion{reg_sign} membrane is presented in order to measure water content and through-plane gradients in situ under disparate temperature and humidification conditions.

  17. Institutional limits to the internalization of work systems : A comparative study of three Japanese multinational companies in the UK

    NARCIS (Netherlands)

    Saka, A

    2002-01-01

    This study adopts a multilevel comparative approach to investigating the degree to which Japanese work systems are implemented and internalized in the UK business system. The focus is on the limits to accepting the continuous improvement schemes of Japanese multinational corporations. The article

  18. A large-sized bubbling appearance of the glomerular basement membrane in a patient with pulmonary limited AL amyloidosis and a past history of lupus nephritis.

    Science.gov (United States)

    Suga, Norihiro; Miura, Naoto; Uemura, Yuko; Nakamura, Toshinobu; Morita, Hiroyuki; Banno, Shogo; Imai, Hirokazu

    2011-12-01

    We report an unusual pathological finding, a large-sized bubbling appearance of the glomerular basement membrane (GBM), in a patient with pulmonary limited AL amyloidosis and a past history of lupus nephritis. The first renal biopsy specimen from 10 years ago, when systemic lupus erythematosus was diagnosed, demonstrated mild mesangial proliferation and subepithelial deposits (WHO classification: III + V). Light microscopy of the current biopsy using periodic acid methenamine silver (PAMS) stain demonstrated a large-sized bubbling appearance of the GBM; however, very weak immunoglobulin and complement deposition was observed in immunofluorescence studies. Routine electron microscopy demonstrated partial subendothelial expansion with electron-lucent materials, but no electron-dense deposits or amyloid fibrils. Electron microscopy with PAMS stain revealed electron-lucent endothelial scalloping, including some cellular components and microspheres in the GBM; however, it is not clear if these materials are derived from endothelial cells. One possibility is that these unique findings represent a recovery phase of lupus membranous nephritis; another is that these findings correspond to a new disease entity.

  19. Internalization of G-protein-coupled receptors: Implication in receptor function, physiology and diseases.

    Science.gov (United States)

    Calebiro, Davide; Godbole, Amod

    2018-04-01

    G protein-coupled receptors (GPCRs) are the largest family of membrane receptors and mediate the effects of numerous hormones and neurotransmitters. The nearly 1000 GPCRs encoded by the human genome regulate virtually all physiological functions and are implicated in the pathogenesis of prevalent human diseases such as thyroid disorders, hypertension or Parkinson's disease. As a result, 30-50% of all currently prescribed drugs are targeting these receptors. Once activated, GPCRs induce signals at the cell surface. This is often followed by internalization, a process that results in the transfer of receptors from the plasma membrane to membranes of the endosomal compartment. Internalization was initially thought to be mainly implicated in signal desensitization, a mechanism of adaptation to prolonged receptor stimulation. However, several unexpected functions have subsequently emerged. Most notably, accumulating evidence indicates that internalization can induce prolonged receptor signaling on intracellular membranes, which is apparently required for at least some biological effects of hormones like TSH, LH and adrenaline. These findings reveal an even stronger connection between receptor internalization and signaling than previously thought. Whereas new studies are just beginning to reveal an important physiological role for GPCR signaling after internalization and ways to exploit it for therapeutic purposes, future investigations will be required to explore its involvement in human disease. Copyright © 2018 Elsevier Ltd. All rights reserved.

  20. Membrane-based seawater desalination: Present and future prospects

    KAUST Repository

    Amy, Gary L.

    2016-10-20

    Given increasing regional water scarcity and that almost half of the world\\'s population lives within 100 km of an ocean, seawater represents a virtually infinite water resource. However, its exploitation is presently limited by the significant specific energy consumption (kWh/m) required by conventional desalination technologies, further exasperated by high unit costs ($/m) and environmental impacts including GHG emissions (g CO-eq/m), organism impingement/entrainment through intakes, and brine disposal through outfalls. This paper explores the state-of-the-art in present seawater desalination practice, emphasizing membrane-based technologies, while identifying future opportunities in step improvements to conventional technologies and development of emerging, potentially disruptive, technologies through advances in material science, process engineering, and system integration. In this paper, seawater reverse osmosis (RO) serves as the baseline conventional technology. The discussion extends beyond desalting processes into membrane-based salinity gradient energy production processes, which can provide an energy offset to desalination process energy requirements. The future membrane landscape in membrane-based desalination and salinity gradient energy is projected to include ultrahigh permeability RO membranes, renewable-energy driven desalination, and emerging processes including closed-circuit RO, membrane distillation, forward osmosis, pressure retarded osmosis, and reverse electrodialysis according various niche applications and/or hybrids, operating separately or in conjunction with RO.

  1. Forward osmosis biomimetic membranes in industrial and environmental applications

    DEFF Research Database (Denmark)

    Bajraktari, Niada; Madsen, Henrik Tækker; Nielsen, K. H.

    consumption and lead to much more stable operations, but is currently limited by the availability of suitable membranes. However, by introducing aquaporin protein channels into a polymeric membrane to make a biomimetic membrane, the vision of both high flux and separation efficiency may be achieved......) a single use filtration module containing a sample reservoir and a biomimetic aquaporin based forward osmosis membrane. 2) a multi-use desktop forward osmosis system containing draw solution mixing, and monitoring devices. The sample is placed in the single use module and the module is then mounted...... a simple unit operation based on osmotic extraction of water from dilute peptide samples with no – or very little loss of sample material. A big challenge in modern water treatment is the handling of micropollutants. One example of these is the pollution of ground-/drinking water with pesticides, which...

  2. S-layer and cytoplasmic membrane – exceptions from the typical archaeal cell wall with a focus on double membranes

    Directory of Open Access Journals (Sweden)

    Andreas eKlingl

    2014-11-01

    Full Text Available The common idea of typical cell wall architecture in archaea consists of a pseudo-crystalline proteinaceous surface layer (S-layer, situated upon the cytoplasmic membrane. This is true for the majority of described archaea, hitherto. Within the crenarchaea, the S-layer often represents the only cell wall component, but there are various exceptions from this wall architecture. Beside (glycosylated S-layers in (hyperthermophilic cren- and euryarchaea as well as halophilic archaea, one can find a great variety of other cell wall structures like proteoglycan-like S-layers (Halobacteria, glutaminylglycan (Natronococci, methanochondroitin (Methanosarcina or double layered cell walls with pseudomurein (Methanothermus and Methanopyrus. The presence of an outermost cellular membrane in the crenarchaeal species Ignicoccus hospitalis already gave indications for an outer membrane similar to Gram-negative bacteria. Although there is just limited data concerning their biochemistry and ultrastructure, recent studies on the euryarchaeal methanogen Methanomassiliicoccus luminyensis, cells of the ARMAN group, and the SM1 euryarchaeon delivered further examples for this exceptional cell envelope type consisting of two membranes.

  3. Monovalent-ion-selective membranes for reserve electrodialysis

    NARCIS (Netherlands)

    Güler, E.; van Baak, Willem; Saakes, Michel; Nijmeijer, Dorothea C.

    2014-01-01

    Reverse electrodialysis (RED) is a process that can be used to generate energy from salinity gradients. Since its application in practice requires the use of natural seawater and river water, the presence of multivalent ions is inevitable, but this currently limits RED performance. Membranes with

  4. Method for calculation of upper limit internal alpha dose rates to aquatic organisms with application of plutonium-239 in plankton

    International Nuclear Information System (INIS)

    Paschoa, A.S.; Baptista, G.B.

    1977-01-01

    A method for the calculation of upper limit internal alpha dose rates to aquatic organisms is presented. The mean alpha energies per disintegration of radionuclides of interest are listed to be used in standard methodologies to calculate dose to aquatic biota. As an application, the upper limits for the alpha dose rates from 239 Pu to the total body of plankton are estimated based on data available in open literature [pt

  5. Giant plasma membrane vesicles: models for understanding membrane organization.

    Science.gov (United States)

    Levental, Kandice R; Levental, Ilya

    2015-01-01

    The organization of eukaryotic membranes into functional domains continues to fascinate and puzzle cell biologists and biophysicists. The lipid raft hypothesis proposes that collective lipid interactions compartmentalize the membrane into coexisting liquid domains that are central to membrane physiology. This hypothesis has proven controversial because such structures cannot be directly visualized in live cells by light microscopy. The recent observations of liquid-liquid phase separation in biological membranes are an important validation of the raft hypothesis and enable application of the experimental toolbox of membrane physics to a biologically complex phase-separated membrane. This review addresses the role of giant plasma membrane vesicles (GPMVs) in refining the raft hypothesis and expands on the application of GPMVs as an experimental model to answer some of key outstanding problems in membrane biology. Copyright © 2015 Elsevier Inc. All rights reserved.

  6. Imaging lipid domains in cell membranes: the advent of super-resolution fluorescence microscopy

    Directory of Open Access Journals (Sweden)

    Dylan Myers Owen

    2013-12-01

    Full Text Available The lipid bilayer of model membranes, liposomes reconstituted from cell lipids, and plasma membrane vesicles and spheres can separate into two distinct liquid phases to yield lipid domains with liquid-ordered and liquid-disordered properties. These observations are the basis of the lipid raft hypothesis that postulates the existence of cholesterol-enriched ordered-phase lipid domains in cell membranes that could regulate protein mobility, localization and interaction. Here we review the evidence that nano-scaled lipid complexes and meso-scaled lipid domains exist in cell membranes and how new fluorescence microscopy techniques that overcome the diffraction limit provide new insights into lipid organization in cell membranes.

  7. Determination and Interpretation of Characteristic Limits for Radioactivity Measurements: Decision Threshhold, Detection Limit and Limits of the Confidence Interval

    International Nuclear Information System (INIS)

    2017-01-01

    Since 2004, the environment programme of the IAEA has included activities aimed at developing a set of procedures for analytical measurements of radionuclides in food and the environment. Reliable, comparable and fit for purpose results are essential for any analytical measurement. Guidelines and national and international standards for laboratory practices to fulfil quality assurance requirements are extremely important when performing such measurements. The guidelines and standards should be comprehensive, clearly formulated and readily available to both the analyst and the customer. ISO 11929:2010 is the international standard on the determination of the characteristic limits (decision threshold, detection limit and limits of the confidence interval) for measuring ionizing radiation. For nuclear analytical laboratories involved in the measurement of radioactivity in food and the environment, robust determination of the characteristic limits of radioanalytical techniques is essential with regard to national and international regulations on permitted levels of radioactivity. However, characteristic limits defined in ISO 11929:2010 are complex, and the correct application of the standard in laboratories requires a full understanding of various concepts. This publication provides additional information to Member States in the understanding of the terminology, definitions and concepts in ISO 11929:2010, thus facilitating its implementation in Member State laboratories.

  8. Modeling kinetics and equilibrium of membranes with fields: Milestoning analysis and implication to permeation

    Energy Technology Data Exchange (ETDEWEB)

    Cardenas, Alfredo E. [Institute for Computational Engineering and Sciences, University of Texas at Austin, Austin, Texas 78712 (United States); Elber, Ron [Institute for Computational Engineering and Sciences, University of Texas at Austin, Austin, Texas 78712 (United States); Department of Chemistry, University of Texas at Austin, Austin, Texas 78712 (United States)

    2014-08-07

    Coarse graining of membrane simulations by translating atomistic dynamics to densities and fields with Milestoning is discussed. The space of the membrane system is divided into cells and the different cells are characterized by order parameters presenting the number densities. The dynamics of the order parameters are probed with Milestoning. The methodology is illustrated here for a phospholipid membrane system (a hydrated bilayer of DOPC (1,2-dioleoyl-sn-glycero-3-phosphocholine) lipid molecules). Significant inhomogeneity in membrane internal number density leads to complex free energy landscape and local maps of transition times. Dynamics and distributions of cavities within the membrane assist the permeation of nonpolar solutes such as xenon atoms. It is illustrated that quantitative and detailed dynamics of water transport through DOPC membrane can be analyzed using Milestoning with fields. The reaction space for water transport includes at least two slow variables: the normal to the membrane plane, and the water density.

  9. Modeling kinetics and equilibrium of membranes with fields: Milestoning analysis and implication to permeation

    International Nuclear Information System (INIS)

    Cardenas, Alfredo E.; Elber, Ron

    2014-01-01

    Coarse graining of membrane simulations by translating atomistic dynamics to densities and fields with Milestoning is discussed. The space of the membrane system is divided into cells and the different cells are characterized by order parameters presenting the number densities. The dynamics of the order parameters are probed with Milestoning. The methodology is illustrated here for a phospholipid membrane system (a hydrated bilayer of DOPC (1,2-dioleoyl-sn-glycero-3-phosphocholine) lipid molecules). Significant inhomogeneity in membrane internal number density leads to complex free energy landscape and local maps of transition times. Dynamics and distributions of cavities within the membrane assist the permeation of nonpolar solutes such as xenon atoms. It is illustrated that quantitative and detailed dynamics of water transport through DOPC membrane can be analyzed using Milestoning with fields. The reaction space for water transport includes at least two slow variables: the normal to the membrane plane, and the water density

  10. Influence of membrane composition on its flexibility

    International Nuclear Information System (INIS)

    Gerbelli, B.B.; Teixeira da Silva, E.R.; Oliveira, C.L.P.; Oliveira, E.A.

    2012-01-01

    Full text: Lamellar phases and vesicles composed of lipids have been used as model systems to investigate biological process related to cell membrane as well as promising carriers for drugs and gene therapy. The composition of the membrane determines its three dimensional shape and its properties such as rigidity and compressibility which play an important role on membrane fusion, protein adhesion, interactions between proteins, etc. We present systematic study of a lamellar system composed mainly of lecithin which is a biocompatible phospholipid and simusol, which is a mixture of fatty acids that acts as a cosurfactant introducing flexibility to the membrane. Using X ray scattering we determine the lamellar periodicity as a function of the hydration for different formulations of the membrane; ranging from 100 % to 50 % mass fraction of lecithin. The X-ray spectra are fitted using a 4 Gaussian model [1]that allows us to determine the lamellar periodicity and the Caille parameter [2]. The ideal swelling law relating the membrane volume fraction (φ m ) to the lamellar periodicity (D) is given by φ m =δ m /D, where δ m is the thickness membrane, however, when steric interactions are dominant with respect to electrostatic and van der Waals interactions, deviations from this behavior are expected [3]. We present experimental data illustrating the swelling behavior for the membrane compositions and the respective behavior of the hydration limit, membrane Luzzati [4], of the Caille parameter and qualitative interpretation of the interaction forces the systems studying the parameter membrane square amplitude fluctuation[5]. [1] Private communication with Prof. Dr. Cristiano Luis Pinto de Oliveira. [2] Caille A. et all, Acad. Sci. Paris B274 (1972) 891. [3] E. Kurtisovski et all, PRL 98, 258103 (2007). [4] Nagle et all, Curr Opin Struct Biol. 2000 Aug;10(4):474-80. [5] H. I. Petrache. Structure and interactions of fluid phospholipids bilayers measured by high resolution

  11. Influence of membrane composition on its flexibility

    Energy Technology Data Exchange (ETDEWEB)

    Gerbelli, B.B.; Teixeira da Silva, E.R.; Oliveira, C.L.P.; Oliveira, E.A. [Universidade de Sao Paulo (USP), SP (Brazil)

    2012-07-01

    Full text: Lamellar phases and vesicles composed of lipids have been used as model systems to investigate biological process related to cell membrane as well as promising carriers for drugs and gene therapy. The composition of the membrane determines its three dimensional shape and its properties such as rigidity and compressibility which play an important role on membrane fusion, protein adhesion, interactions between proteins, etc. We present systematic study of a lamellar system composed mainly of lecithin which is a biocompatible phospholipid and simusol, which is a mixture of fatty acids that acts as a cosurfactant introducing flexibility to the membrane. Using X ray scattering we determine the lamellar periodicity as a function of the hydration for different formulations of the membrane; ranging from 100 % to 50 % mass fraction of lecithin. The X-ray spectra are fitted using a 4 Gaussian model [1]that allows us to determine the lamellar periodicity and the Caille parameter [2]. The ideal swelling law relating the membrane volume fraction ({phi}{sub m}) to the lamellar periodicity (D) is given by {phi}{sub m} ={delta}{sub m}/D, where {delta}{sub m} is the thickness membrane, however, when steric interactions are dominant with respect to electrostatic and van der Waals interactions, deviations from this behavior are expected [3]. We present experimental data illustrating the swelling behavior for the membrane compositions and the respective behavior of the hydration limit, membrane Luzzati [4], of the Caille parameter and qualitative interpretation of the interaction forces the systems studying the parameter membrane square amplitude fluctuation[5]. [1] Private communication with Prof. Dr. Cristiano Luis Pinto de Oliveira. [2] Caille A. et all, Acad. Sci. Paris B274 (1972) 891. [3] E. Kurtisovski et all, PRL 98, 258103 (2007). [4] Nagle et all, Curr Opin Struct Biol. 2000 Aug;10(4):474-80. [5] H. I. Petrache. Structure and interactions of fluid phospholipids

  12. Barodiffusion phenomena at active transport of na+ and K+ ions through the cell membrane

    International Nuclear Information System (INIS)

    Khrapijchuk, G.V.; Chalyi, A.V.; Nurishchenko, N.Je.

    2010-01-01

    The influence of ultrasound as the significant motive force of barodiffusion phenomena at the processes of active transport of Na + and K + ions through the cell membrane is considered. The dependence of membrane potential is theoretically estimated at active transport of natrium and potassium ions on the ultrasound intensity and pressure overfall between external and internal medium of the cell.

  13. Damage of Escherichia coli membrane by bactericidal agent polyhexamethylene guanidine hydrochloride: micrographic evidences.

    Science.gov (United States)

    Zhou, Z X; Wei, D F; Guan, Y; Zheng, A N; Zhong, J J

    2010-03-01

    The purpose of this study was to provide micrographic evidences for the damaged membrane structure and intracellular structure change of Escherichia coli strain 8099, induced by polyhexamethylene guanidine hydrochloride (PHMG). The bactericidal effect of PHMG on E. coli was investigated based on beta-galactosidase activity assay, fluorescein-5-isothiocyanate confocal laser scanning microscopy, field emission scanning electron microscopy and transmission electron microscopy. The results revealed that a low dose (13 microg ml(-1)) of PHMG slightly damaged the outer membrane structure of the treated bacteria and increased the permeability of the cytoplasmic membrane, while no significant damage was observed to the morphological structure of the cells. A high dose (23 microg ml(-1)) of PHMG collapsed the outer membrane structure, led to the formation of a local membrane pore across the membrane and badly damaged the internal structure of the cells. Subsequently, intracellular components were leaked followed by cell inactivation. Dose-dependent membrane disruption was the main bactericidal mechanism of PHMG. The formation of the local membrane pores was probable after exposure to a high dose (23 microg ml(-1)) of PHMG. Micrographic evidences were provided about the damaged membrane structure and intracellular structure change of E. coli. The presented information helps understand the bactericidal mechanism of PHMG by membrane damage.

  14. Interaction Free Energies of Eight Sodium Salts and a Phosphatidylcholine Membrane

    DEFF Research Database (Denmark)

    Wang, C. H.; Ge, Y.; Mortensen, J.

    2011-01-01

    Many recent reports have discussed specific effects of anions on the properties of lipid membranes and possible roles of such effects within biochemistry. One key parameter in both theoretical and experimental treatments of membrane-salt interactions is the net affinity, that is, the free energy...... salts by dialysis equilibrium measurements. This method provides model free thermodynamic data and allows investigations in the dilute concentration range where solution nonideality and perturbation of membrane structure is limited. The transfer free energy of DMPC from water to salt solutions, Delta mu...

  15. Elaboration by tape-casting and co-sintering of multilayer catalytic membrane reactor- performances

    International Nuclear Information System (INIS)

    Julian, A.

    2008-12-01

    This research deals with the increasing interest of the conversion of natural gas into liquid fuels (diesel, kerosene) using the Gas To Liquid (GTL) process. Within this context, Catalytic Membrane-based Reactors (CMR) would allow an improvement of the process efficiency and a reduction of investment and production costs with respect to the present technologies. They allow performing the separation of oxygen from air, and the conversion of natural gas into synthesis gas within a single step. After having highlighted the economical and technological advantages of using a ceramic membrane for the production of syngas (H 2 + CO 2 ), the author describes the protocols of synthesis of powders selected for the dense membrane and the porous support, and their physical characteristics. The obtained powders are then adapted to the tape-casting forming process. Graded-composition multilayer structures and microstructure are then elaborated by co-sintering. Performances in terms of membrane oxygen flows are presented. Mechanisms limiting the oxygen flow are discussed in order to propose ways of improving membrane performances. The limits of the studied system are defined in terms of elastic properties, and optimization ways are proposed for the dense membrane material composition in terms of mechanical properties and performance in oxygen semi-permeation

  16. Choroidal neovascular membrane

    Directory of Open Access Journals (Sweden)

    Bhatt Nitul

    1998-01-01

    Full Text Available Choroidal neovascular membrane in the macular area is one of the leading causes of severe visual loss. Usually a manifestation in elderly population, it is often associated with age-related macular degeneration. The current mainstay of management is early diagnosis, usually by fundus examination, aided by angiography and photocoagulation in selected cases. Various other modalities of treatment including surgery are being considered as alternate options, but with limited success. The purpose of this review is to briefly outline the current concepts and the management strategy from a clinician′s viewpoint.

  17. Choroidal neovascular membrane.

    Science.gov (United States)

    Bhatt, N S; Diamond, J G; Jalali, S; Das, T

    1998-06-01

    Choroidal neovascular membrane in the macular area is one of the leading causes of severe visual loss. Usually a manifestation in elderly population, it is often associated with age-related macular degeneration. The current mainstay of management is early diagnosis, usually by fundus examination, aided by angiography and photocoagulation in selected cases. Various other modalities of treatment including surgery are being considered as alternate options, but with limited success. The purpose of this review is to briefly outline the current concepts and the management strategy from a clinician's viewpoint.

  18. Polyurethane Nanofiber Membranes for Waste Water Treatment by Membrane Distillation

    Directory of Open Access Journals (Sweden)

    T. Jiříček

    2017-01-01

    Full Text Available Self-sustained electrospun polyurethane nanofiber membranes were manufactured and tested on a direct-contact membrane distillation unit in an effort to find the optimum membrane thickness to maximize flux rate and minimize heat losses across the membrane. Also salt retention and flux at high salinities up to 100 g kg−1 were evaluated. Even though the complex structure of nanofiber layers has extreme specific surface and porosity, membrane performance was surprisingly predictable; the highest flux was achieved with the thinnest membranes and the best energy efficiency was achieved with the thickest membranes. All membranes had salt retention above 99%. Nanotechnology offers the potential to find modern solutions for desalination of waste waters, by introducing new materials with revolutionary properties, but new membranes must be developed according to the target application.

  19. Temperature-programmed desorption for membrane inlet mass spectrometry

    DEFF Research Database (Denmark)

    Ketola, R.A.; Grøn, C.; Lauritsen, F.R.

    1998-01-01

    We present a novel technique for analyzing volatile organic compounds in air samples using a solid adsorbent together with temperature-programmed desorption and subsequent detection by membrane inlet mass spectrometry (TPD-MIMS). The new system has the advantage of a fast separation of compounds...... to diffuse through the membrane into the mass spectrometer in a few seconds. In this fashion we could completely separate many similar volatile compounds, for example toluene from xylene and trichloroethene from tetrachloroethene. Typical detection limits were at low or sub-nanogram levels, the dynamic range...

  20. Use of Novel Reinforced Cation Exchange Membranes for Microbial Fuel Cells

    International Nuclear Information System (INIS)

    Kamaraj, Sathish-Kumar; Romano, Sergio Mollá; Moreno, Vicente Compañ; Poggi-Varaldo, H.M.; Solorza-Feria, O.

    2015-01-01

    This work has been focused on the synthesis and characterization of different blended membranes SPEEK-35PVA (Water), SPEEK-35PVA (DMAc) prepared by casting and nanofiber-reinforced proton exchange membranes Nafion-PVA-15, Nafion-PVA-23 and SPEEK/PVA-PVB. The two first reinforced membranes were made up of Nafion® polymer deposited between polyvinyl alcohol (PVA) nanofibers. The last composite membrane is considered because the PVA is a hydrophilic polymer which forms homogeneous blends with SPEEK suitable to obtain high proton conductivity, while the hydrophobic PVB can produce blends in a phase separation morphology in which very low water uptake can be found. The synthesized membranes showed an outstanding stability, high proton conductivity, and enhanced mechanical and barrier properties. The membranes were characterized in single chamber microbial fuel cells (SCMFCs) using electrochemically enriched high sodic saline hybrid H-inocula (Geobacter metallireducen, Desulfurivibrio alkaliphilus, and Marinobacter adhaerens) as biocatalyst. The best performance was obtained with Nafion-PVA-15 membrane, which achieved a maximum power density of 1053 mW/m 3 at a cell voltage of 340 mV and displayed the lowest total internal resistance (Rint ≈ 522 Ω). This result is in agreement with the low oxygen permeability and the moderate conductivity found in this kind of membranes. These results are encouraging towards obtaining high concentrated sodic saline model wastewater exploiting MFCs

  1. Membrane crystallization for recovery of salts from produced water

    DEFF Research Database (Denmark)

    Quist-Jensen, Cejna Anna; Jensen, Henriette Casper; Ali, Aamer

    Membrane Crystallization (MCr) is a novel technology able to recover freshwater and high-purity salts from complex solutions and therefore, is suggested for a better exploitation of wastewater streams. Unlike other membrane processes, MCr is not limited by high concentrations and, therefore, the ......, the membrane maintained its hydrophobic nature despite that produced water contained oil residues. Conductivity and HPLC was utilized to analyze the quality of the permeate stream......., the solutions can be treated to achieve saturation level. Hereby different salts can be precipitated and directly recovered from various streams. In this study, it is shown that MCr is able to treat produced water by producing clean water and simultaneously NaCl crystals. The recovered crystals exhibited high...

  2. Electrodialysis of boron-containing solutions using homogeneuos ionite membranes

    International Nuclear Information System (INIS)

    Pilipenko, A.T.; Grebenyuk, V.D.; Mel'nik, L.A.

    1989-01-01

    Electrodialysis of boron-containing solutions is studied when preparing potable water from the sea one with the limiting admissible concentration (LAC) of boron 0.5 mg/dm 3 . It is ascertained that at pH>7 diffusion permeability of anion- and cation-exchange membranes as regards boron reduces both in the absence of external field and at current density 0.3 A/dm 3 . It is shown that when MK-100 homogeneous cationic membranes and MA-100 homogeneous anionic membranes are used, boron concentration in dialyzate decreases to LAC, if the process is realized in acid and low-acid media and if the depth of freshening increases to 0.2g/l

  3. Polybenzimidazole membranes for zero gap alkaline electrolysis cells

    DEFF Research Database (Denmark)

    Kraglund, Mikkel Rykær; Aili, David; Christensen, Erik

    Membranes of m-PBI doped in KOH (aq), 15-35 wt%, show high ionic conductivity in the temperature range 20-80 ºC. In electrolysis cells with nickel foam electrodes m-PBI membranesprovide low internal resistance. With a 60 µm membraneat 80ºC in 20 wt% KOH,1000 mA/cm2 is achieved at 2.25....

  4. The Effect of Platinum Electrocatalyst on Membrane Degradation in Polymer Electrolyte Fuel Cells.

    Science.gov (United States)

    Bodner, Merit; Cermenek, Bernd; Rami, Mija; Hacker, Viktor

    2015-12-08

    Membrane degradation is a severe factor limiting the lifetime of polymer electrolyte fuel cells. Therefore, obtaining a deeper knowledge is fundamental in order to establish fuel cells as competitive product. A segmented single cell was operated under open circuit voltage with alternating relative humidity. The influence of the catalyst layer on membrane degradation was evaluated by measuring a membrane without electrodes and a membrane-electrode-assembly under identical conditions. After 100 h of accelerated stress testing the proton conductivity of membrane samples near the anode and cathode was investigated by means of ex situ electrochemical impedance spectroscopy. The membrane sample near the cathode inlet exhibited twofold lower membrane resistance and a resulting twofold higher proton conductivity than the membrane sample near the anode inlet. The results from the fluoride ion analysis have shown that the presence of platinum reduces the fluoride emission rate; which supports conclusions drawn from the literature.

  5. Desipramine induces disorder in cholesterol-rich membranes: implications for viral trafficking

    Science.gov (United States)

    Pakkanen, Kirsi; Salonen, Emppu; Mäkelä, Anna R.; Oker-Blom, Christian; Vattulainen, Ilpo; Vuento, Matti

    2009-12-01

    In this study, the effect of desipramine (DMI) on phospholipid bilayers and parvoviral entry was elucidated. In atomistic molecular dynamics simulations, DMI was found to introduce disorder in cholesterol-rich phospholipid bilayers. This was manifested by a decrease in the deuterium order parameter SCD as well as an increase in the membrane area. Disordering of the membrane suggested DMI to destabilize cholesterol-rich membrane domains (rafts) in cellular conditions. To relate the raft disrupting ability of DMI with novel biological relevance, we studied the intracellular effect of DMI using canine parvovirus (CPV), a virus known to interact with endosomal membranes and sphingomyelin, as an intracellular probe. DMI was found to cause retention of the virus in intracellular vesicular structures leading to the inhibition of viral proliferation. This implies that DMI has a deleterious effect on the viral traffic. As recycling endosomes and the internal vesicles of multivesicular bodies are known to contain raft components, the effect of desipramine beyond the plasma membrane step could be caused by raft disruption leading to impaired endosomal function and possibly have direct influence on the penetration of the virus through an endosomal membrane.

  6. Desipramine induces disorder in cholesterol-rich membranes: implications for viral trafficking

    International Nuclear Information System (INIS)

    Pakkanen, Kirsi; Mäkelä, Anna R; Oker-Blom, Christian; Vuento, Matti; Salonen, Emppu; Vattulainen, Ilpo

    2009-01-01

    In this study, the effect of desipramine (DMI) on phospholipid bilayers and parvoviral entry was elucidated. In atomistic molecular dynamics simulations, DMI was found to introduce disorder in cholesterol-rich phospholipid bilayers. This was manifested by a decrease in the deuterium order parameter S CD as well as an increase in the membrane area. Disordering of the membrane suggested DMI to destabilize cholesterol-rich membrane domains (rafts) in cellular conditions. To relate the raft disrupting ability of DMI with novel biological relevance, we studied the intracellular effect of DMI using canine parvovirus (CPV), a virus known to interact with endosomal membranes and sphingomyelin, as an intracellular probe. DMI was found to cause retention of the virus in intracellular vesicular structures leading to the inhibition of viral proliferation. This implies that DMI has a deleterious effect on the viral traffic. As recycling endosomes and the internal vesicles of multivesicular bodies are known to contain raft components, the effect of desipramine beyond the plasma membrane step could be caused by raft disruption leading to impaired endosomal function and possibly have direct influence on the penetration of the virus through an endosomal membrane

  7. Fouling in Membrane Distillation, Osmotic Distillation and Osmotic Membrane Distillation

    Directory of Open Access Journals (Sweden)

    Mourad Laqbaqbi

    2017-03-01

    Full Text Available Various membrane separation processes are being used for seawater desalination and treatment of wastewaters in order to deal with the worldwide water shortage problem. Different types of membranes of distinct morphologies, structures and physico-chemical characteristics are employed. Among the considered membrane technologies, membrane distillation (MD, osmotic distillation (OD and osmotic membrane distillation (OMD use porous and hydrophobic membranes for production of distilled water and/or concentration of wastewaters for recovery and recycling of valuable compounds. However, the efficiency of these technologies is hampered by fouling phenomena. This refers to the accumulation of organic/inorganic deposits including biological matter on the membrane surface and/or in the membrane pores. Fouling in MD, OD and OMD differs from that observed in electric and pressure-driven membrane processes such electrodialysis (ED, membrane capacitive deionization (MCD, reverse osmosis (RO, nanofiltration (NF, ultrafiltration (UF, microfiltration (MF, etc. Other than pore blockage, fouling in MD, OD and OMD increases the risk of membrane pores wetting and reduces therefore the quantity and quality of the produced water or the concentration efficiency of the process. This review deals with the observed fouling phenomena in MD, OD and OMD. It highlights different detected fouling types (organic fouling, inorganic fouling and biofouling, fouling characterization techniques as well as various methods of fouling reduction including pretreatment, membrane modification, membrane cleaning and antiscalants application.

  8. Deashing of coal liquids with ceramic membrane microfiltration and diafiltration

    Energy Technology Data Exchange (ETDEWEB)

    Bishop, B.; Goldsmith, R. [CeraMem Corp., Waltham, MA (United States)

    1995-12-31

    Removal of mineral matter from liquid hydrocarbons derived from the direct liquefaction of coal is required for product acceptability. Current methods include critical solvent deashing (Rose{sup {reg_sign}} process from Kerr-McGee) and filtration (U.S. Filter leaf filter as used by British Coal). These methods produce ash reject streams containing up to 15% of the liquid hydrocarbon product. Consequently, CeraMem proposed the use of low cost, ceramic crossflow membranes for the filtration of coal liquids bottoms to remove mineral matter and subsequent diafiltration (analogous to cake washing in dead-ended filtration) for the removal of coal liquid from the solids stream. The use of these ceramic crossflow membranes overcomes the limitations of traditional polymeric crossflow membranes by having the ability to operate at elevated temperature and to withstand prolonged exposure to hydrocarbon and solvent media. In addition, CeraMem`s membrane filters are significantly less expensive than competitive ceramic membranes due to their unique construction. With these ceramic membrane filters, it may be possible to reduce the product losses associated with traditional deashing processes at an economically attractive cost. The performance of these ceramic membrane microfilters is discussed.

  9. Interaction of ADP, atractyloside, and gummiferin on the ADP translocase of the inner mitochondrial membrane

    Energy Technology Data Exchange (ETDEWEB)

    Vignais, P V; Vignais, P M; Defaye, G; Lauquin, G; Doussiere, J; Chabert, J; Brandolin, G

    1972-05-01

    From international conference on mechanism in bioenergetica; Bari, Italy (1 May 1972). Two specific inhibitors of the adenine nucleotide translocation, gummiferin (GUM), identified to 4-carboxyatractyloside and atractyloside (ATR), were labeled with /sup 35/S and their binding properties to whole mitochondria and inner mitochondrial membrane vesicles used to monitor changes of membrane conformation induced by ADP. (auth)

  10. Ion permeability of the cytoplasmic membrane limits the maximum growth temperature of bacteria and archaea

    NARCIS (Netherlands)

    van de Vossenberg, J.L C M; Ubbink-Kok, T.; Elferink, M.G.L.; Driessen, A.J.M.; Konings, W.N

    1995-01-01

    Protons and sodium ions are the most commonly used coupling ions in energy transduction in bacteria and archaea. At their growth temperature, the permeability of the cytoplasmic membrane of thermophilic bacteria to protons is high compared with that of sodium ions. In some thermophiles, sodium is

  11. The relevance of polymeric synthetic membranes in topical formulation assessment and drug diffusion study.

    Science.gov (United States)

    Ng, Shiow-Fern; Rouse, Jennifer J; Sanderson, Francis D; Eccleston, Gillian M

    2012-03-01

    Synthetic membranes are composed of thin sheets of polymeric macromolecules that can control the passage of components through them. Generally, synthetic membranes used in drug diffusion studies have one of two functions: skin simulation or quality control. Synthetic membranes for skin simulation, such as the silicone-based membranes polydimethylsiloxane and Carbosil, are generally hydrophobic and rate limiting, imitating the stratum corneum. In contrast, synthetic membranes for quality control, such as cellulose esters and polysulfone, are required to act as a support rather than a barrier. These synthetic membranes also often contain pores; hence, they are called porous membranes. The significance of Franz diffusion studies and synthetic membranes in quality control studies involves an understanding of the fundamentals of synthetic membranes. This article provides a general overview of synthetic membranes, including a brief background of the history and the common applications of synthetic membranes. This review then explores the types of synthetic membranes, the transport mechanisms across them, and their relevance in choosing a synthetic membrane in Franz diffusion cell studies for formulation assessment purposes.

  12. Tokamak pump limiters

    International Nuclear Information System (INIS)

    Conn, R.W.

    1984-05-01

    Recent experiments with a scoop limiter without active internal pumping have been carried out in the PDX tokamak with up to 6MW of auxiliary neutral beam heating. Experiments have also been done with a rotating head pump limiter in the PLT tokamak in conjunction with RF plasma heating. Extensive experiments have been done in the ISX-B tokamak and first experiments have been completed with the ALT-I limiter in TEXTOR. The pump limiter modules in these latter two machines have internal getter pumping. Experiments in ISX-B are with ohmic and auxiliary neutral beam heating. The results in ISX-B and TEXTOR show that active density control and particle removal is achieved with pump limiters. In ISX-B, the boundary layer (or scape-off layer) plasma partially screens the core plasma from gas injection. In both ISX-B and TEXTOR, the pressure internal to the module scales linearly with plasma density but in ISX-B, with neutral beam injection, a nonlinear increase is observed at the highest densities studied. Plasma plugging is the suspected cause. Results from PDX suggest that a region may exist in which core plasma energy confinement improves using a pump limiter during neutral beam injection. Asymmetric radial profiles and an increased edge electron temperature are observed in discharges with improved confinement. The injection of small amounts of neon into ISX-B has more clearly shown an improved electron core energy confinement during neutral beam injection. While carried out with a regular limiter, this Z-mode of operation is ideal for use with pump limiters and should be a way to achieve energy confinement times similar to values for H-mode tokamak plasmas. The implication of all these results for the design of a reactor pump limiter is described

  13. Tokamak pump limiters

    International Nuclear Information System (INIS)

    Conn, R.W.; California Univ., Los Angeles

    1984-01-01

    Recent experiments with a scoop limiter without active internal pumping have been carried out in the PDX tokamak with up to 6 MW of auxiliary neutral beam heating. Experiments have also been performed with a rotating head pump limiter in the PLT tokamak in conjunction with RF plasma heating. Extensive experiments have been done in the ISX-B tokamak and first experiments have been completed with the ALT-I limiter in TEXTOR. The pump limiter modules in these latter two machines have internal getter pumping. Experiments in ISX-B are with ohmic and auxiliary neutral beam heating. The results in ISX-B and TEXTOR show that active density control and particle removal is achieved with pump limiters. In ISX-B, the boundary layer (or scrape-off layer) plasma partially screens the core plasma from gas injection. In both ISX-B and TEXTOR, the pressure internal to the module scales linearly with plasma density but in ISX-B, with neutral beam injection, a nonlinear increase is observed at the highest densities studied. Plasma plugging is the suspected cause. Results from PDX suggest that a regime may exist in which core plasma energy confinement improves using a pump limiter during neutral beam injection. Asymmetric radial profiles and an increased edge electron temperature are observed in discharges with improved confinement. The injection of small amounts of neon into ISX-B has more clearly shown an improved electron core energy confinement during neutral beam injection. While carried out with a regular limiter, this 'Z-mode' of operation is ideal for use with pump limiters and should be a way to achieve energy confinement times similar to values for H-mode tokamak plasmas. The implication of all these results for the design of a reactor pump limiter is described. (orig.)

  14. Approach for Self-Calibrating CO₂ Measurements with Linear Membrane-Based Gas Sensors.

    Science.gov (United States)

    Lazik, Detlef; Sood, Pramit

    2016-11-17

    Linear membrane-based gas sensors that can be advantageously applied for the measurement of a single gas component in large heterogeneous systems, e.g., for representative determination of CO₂ in the subsurface, can be designed depending on the properties of the observation object. A resulting disadvantage is that the permeation-based sensor response depends on operating conditions, the individual site-adapted sensor geometry, the membrane material, and the target gas component. Therefore, calibration is needed, especially of the slope, which could change over several orders of magnitude. A calibration-free approach based on an internal gas standard is developed to overcome the multi-criterial slope dependency. This results in a normalization of sensor response and enables the sensor to assess the significance of measurement. The approach was proofed on the example of CO₂ analysis in dry air with tubular PDMS membranes for various CO₂ concentrations of an internal standard. Negligible temperature dependency was found within an 18 K range. The transformation behavior of the measurement signal and the influence of concentration variations of the internal standard on the measurement signal were shown. Offsets that were adjusted based on the stated theory for the given measurement conditions and material data from the literature were in agreement with the experimentally determined offsets. A measurement comparison with an NDIR reference sensor shows an unexpectedly low bias (sensor response, and comparable statistical uncertainty.

  15. Carbon dioxide (hydrogen sulfide) membrane separations and WGS membrane reactor modeling for fuel cells

    Science.gov (United States)

    Huang, Jin

    Acid-gas removal is of great importance in many environmental or energy-related processes. Compared to current commercial technologies, membrane-based CO2 and H2S capture has the advantages of low energy consumption, low weight and space requirement, simplicity of installation/operation, and high process flexibility. However, the large-scale application of the membrane separation technology is limited by the relatively low transport properties. In this study, CO2 (H2S)-selective polymeric membranes with high permeability and high selectivity have been studied based on the facilitated transport mechanism. The membrane showed facilitated effect for both CO2 and H2S. A CO2 permeability of above 2000 Barrers, a CO2/H2 selectivity of greater than 40, and a CO2/N2 selectivity of greater than 200 at 100--150°C were observed. As a result of higher reaction rate and smaller diffusing compound, the H2S permeability and H2S/H2 selectivity were about three times higher than those properties for CO2. The novel CO2-selective membrane has been applied to capture CO 2 from flue gas and natural gas. In the CO2 capture experiments from a gas mixture with N2 and H2, a permeate CO 2 dry concentration of greater than 98% was obtained by using steam as the sweep gas. In CO2/CH4 separation, decent CO 2 transport properties were obtained with a feed pressure up to 500 psia. With the thin-film composite membrane structure, significant increase on the CO2 flux was achieved with the decrease of the selective layer thickness. With the continuous removal of CO2, CO2-selective water-gas-shift (WGS) membrane reactor is a promising approach to enhance CO conversion and increase the purity of H2 at process pressure under relatively low temperature. The simultaneous reaction and transport process in the countercurrent WGS membrane reactor was simulated by using a one-dimensional non-isothermal model. The modeling results show that a CO concentration of less than 10 ppm and a H2 recovery of greater

  16. 26 CFR 1.904(i)-1 - Limitation on use of deconsolidation to avoid foreign tax credit limitations.

    Science.gov (United States)

    2010-04-01

    ... foreign tax credit limitations. 1.904(i)-1 Section 1.904(i)-1 Internal Revenue INTERNAL REVENUE SERVICE... United States § 1.904(i)-1 Limitation on use of deconsolidation to avoid foreign tax credit limitations... applying the foreign tax credit provisions of section 59(a), sections 901 through 908, and section 960, the...

  17. Human endothelial progenitor cells internalize high-density lipoprotein.

    Directory of Open Access Journals (Sweden)

    Kaemisa Srisen

    Full Text Available Endothelial progenitor cells (EPCs originate either directly from hematopoietic stem cells or from a subpopulation of monocytes. Controversial views about intracellular lipid traffic prompted us to analyze the uptake of human high density lipoprotein (HDL, and HDL-cholesterol in human monocytic EPCs. Fluorescence and electron microscopy were used to investigate distribution and intracellular trafficking of HDL and its associated cholesterol using fluorescent surrogates (bodipy-cholesterol and bodipy-cholesteryl oleate, cytochemical labels and fluorochromes including horseradish peroxidase and Alexa Fluor® 568. Uptake and intracellular transport of HDL were demonstrated after internalization periods from 0.5 to 4 hours. In case of HDL-Alexa Fluor® 568, bodipy-cholesterol and bodipy-cholesteryl oleate, a photooxidation method was carried out. HDL-specific reaction products were present in invaginations of the plasma membrane at each time of treatment within endocytic vesicles, in multivesicular bodies and at longer periods of uptake, also in lysosomes. Some HDL-positive endosomes were arranged in form of "strings of pearl"- like structures. HDL-positive multivesicular bodies exhibited intensive staining of limiting and vesicular membranes. Multivesicular bodies of HDL-Alexa Fluor® 568-treated EPCs showed multilamellar intra-vacuolar membranes. At all periods of treatment, labeled endocytic vesicles and organelles were apparent close to the cell surface and in perinuclear areas around the Golgi apparatus. No HDL-related particles could be demonstrated close to its cisterns. Electron tomographic reconstructions showed an accumulation of HDL-containing endosomes close to the trans-Golgi-network. HDL-derived bodipy-cholesterol was localized in endosomal vesicles, multivesicular bodies, lysosomes and in many of the stacked Golgi cisternae and the trans-Golgi-network Internalized HDL-derived bodipy-cholesteryl oleate was channeled into the lysosomal

  18. Differential natural organic matter fouling of ceramic versus polymeric ultrafiltration membranes.

    Science.gov (United States)

    Lee, Seung-Jin; Kim, Jae-Hong

    2014-01-01

    Ceramic ultrafiltration membranes has drawn increasing attention in drinking water treatment sectors as an alternative to traditional polymeric counterparts, yet only limited information has been made available about the characteristics of ceramic membrane fouling by natural organic matter. The effects of solution chemistry including ionic strength, divalent ion concentration and pH on the flux behavior were comparatively evaluated for ceramic and polymeric ultrafiltration of synthetic water containing model natural organic matter. Filtration characteristics were further probed via resistance-in-series model analysis, fouling visualization using quantum dots, batch adsorption test, contact angle measurement, solute-membrane surface adhesion force measurement, and quantitative comparison of fouling characteristics between ceramic and polymeric membranes. The results collectively suggested that the effects of solution chemistry on fouling behavior of ceramic membranes were generally similar to polymeric counterparts in terms of trends, while the extent varied significantly depending on water quality parameters. Lower fouling tendency and enhanced cleaning efficiency were observed with the ceramic membrane, further promoting the potential for ceramic membrane application to surface water treatment. Copyright © 2013 Elsevier Ltd. All rights reserved.

  19. The establishment of polarized membrane traffic in Xenopus laevis embryos.

    Science.gov (United States)

    Roberts, S J; Leaf, D S; Moore, H P; Gerhart, J C

    1992-09-01

    Delineation of apical and basolateral membrane domains is a critical step in the epithelialization of the outer layer of cells in the embryo. We have examined the initiation of polarized membrane traffic in Xenopus and show that membrane traffic is not polarized in oocytes but polarized membrane domains appear at first cleavage. The following proteins encoded by injected RNA transcripts were used as markers to monitor membrane traffic: (a) VSV G, a transmembrane glycoprotein preferentially inserted into the basolateral surface of polarized epithelial cells; (b) GThy-1, a fusion protein of VSV G and Thy-1 that is localized to the apical domains of polarized epithelial cells; and (c) prolactin, a peptide hormone that is not polarly secreted. In immature oocytes, there is no polarity in the expression of VSV G or GThy-1, as shown by the constitutive expression of both proteins at the surface in the animal and vegetal hemispheres. At meiotic maturation, membrane traffic to the surface is blocked; the plasma membrane no longer accepts the vesicles synthesized by the oocyte (Leaf, D. L., S. J. Roberts, J. C. Gerhart, and H.-P. Moore. 1990. Dev. Biol. 141:1-12). When RNA transcripts are injected after fertilization, VSV G is expressed only in the internal cleavage membranes (basolateral orientation) and is excluded from the outer surface (apical orientation, original oocyte membrane). In contrast, GThy-1 and prolactin, when expressed in embryos, are inserted or released at both the outer membrane derived from the oocyte and the inner cleavage membranes. Furthermore, not all of the cleavage membrane comes from an embryonic pool of vesicles--some of the cleavage membrane comes from vesicles synthesized during oogenesis. Using prolactin as a marker, we found that a subset of vesicles synthesized during oogenesis was only released after fertilization. However, while embryonic prolactin was secreted from both apical and basolateral surfaces, the secretion of oogenic prolactin

  20. 3-D Printed Biocompatible Micro-Bellows Membranes

    KAUST Repository

    Moussi, Khalil

    2018-04-11

    Bellows membranes are essential elements in many actuator devices. Currently, the size, shape, and dimensions of bellows membranes are limited by the fabrication process constraints. Miniaturizing the bellows membranes is a prerequisite for the development of integrated systems with novel capabilities as needed, for example, in advanced biomedical devices. Using a two-photon polymerization, 3-D printing technique, we present a high-resolution, high-yield, and customizable manufacturing process to produce Parylene C micro-bellows. An optimization of the crucial design parameters is performed using finite element modeling from which designs with high deflection and low stress were obtained. Different micro-bellows designs are fabricated and characterized. The total volume of the fabricated models ranges from 3 to 0.3 mm³ and the minimum feature size is 60 μm. The achieved cumulative deflection ranges from 300 to 570 μm. [2017-0307