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Passalacqua, Enza, Rolando Pedicini, Alessandra Carbone, Irene Gatto, Fabio Matera, Assunta Patti e Ada Saccà. "Effects of the Chemical Treatment on the Physical-Chemical and Electrochemical Properties of the Commercial Nafion™ NR212 Membrane". Materials 13, n.º 22 (20 de novembro de 2020): 5254. http://dx.doi.org/10.3390/ma13225254.
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Polymer Electrolyte Fuel Cells (PEFCs) are one of the most promising power generation systems. The main component of a PEFC is the proton exchange membrane (PEM), object of intense research to improve the efficiency of the cell. The most commonly and commercially successful used PEMs are Nafion™ perfluorosulfonic acid (PFSA) membranes, taken as a reference for the development of innovative and alternative membranes. Usually, these membranes undergo different pre-treatments to enhance their characteristics. With the aim of understanding the utility and the effects of such pre-treatments, in this study, a commercial Nafion™ NR212 membrane was subjected to two different chemical pre-treatments, before usage. HNO3 or H2O2 were selected as chemical agents because the most widely used ones in the procedure protocols in order to prepare the membrane in a well-defined reference state. The pre-treated membranes properties were compared to an untreated membrane, used as-received. The investigation has showed that the pre-treatments enhance the hydrophilicity and increase the water molecules coordinated to the sulphonic groups in the membrane structure, on the other hand the swelling of the membranes also increases. As a consequence, the untreated membrane shows a better mechanical resistance, a good electrochemical performance and durability in fuel cell operations, orienting toward the use of the NR212 membrane without any chemical pre-treatment.
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Malczewska, Beata, Paweł Lochyński, Sylwia Charazińska, Andrzej Sikora e Ramin Farnood. "Electrospun Silica-Polyacrylonitrile Nanohybrids for Water Treatments". Membranes 13, n.º 1 (6 de janeiro de 2023): 72. http://dx.doi.org/10.3390/membranes13010072.
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In this work, the removal of NOM (natural organic matter) as represented by humic acid by means of electrospun nanofiber adsorptive membranes (ENAMs) is described. Polyacrylonitrile (PAN) was used for the preparation of ENAMs incorporating silica nanoparticles as adsorbents. The addition of silica to the polymer left visible changes on the structural morphology and fibers’ properties of the membrane. The membrane samples were characterized by pure water permeability, contact angle measurement, SEM, XPS, and XRD. This study assesses the preliminary performance of PAN-Si membranes for the removal of natural organic matter (NOM). The membrane rejected the humic acid, a surrogate of NOM, from 69.57% to 87.5%.
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Cao, Danyu, Lili Gai, Debao Niu, Yarong Li, Jianbin Li, Run Tian e Kai Li. "Purification of Camellia Oil by Inorganic Ceramic Membrane". Foods 11, n.º 22 (15 de novembro de 2022): 3644. http://dx.doi.org/10.3390/foods11223644.
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Camellia oil is an edible health oil with high medicinal value. While phospholipids, peroxides, and free fatty acids are present in unrefined camellia virgin oil (CVO), which has a negative impact on the quality characteristics and storage stability. This paper is to investigate the testing effects of transmembrane pressure and temperature on the membrane flux and degumming (the removal of colloidal substances from crude oil and which is mainly phospholipids) to determine the optimum process parameters for the purification of CVO. On this basis, the effects of purification treatments applied by using a membrane system with membranes of different pore sizes (200, 140, 20, 15, and 10 nm) on CVO were tested. The results indicate that the purification treatments of ceramic membrane on CVO reduced the contents of phospholipids (87.0% reduction), peroxides (29.2% reduction), and free fatty acids (16.2% reduction) at a transmembrane pressure of 0.4 MPa and temperature of 60 °C. At the same time, these treatments did not significantly alter the fatty acid composition. Thus, ceramic membranes have the potential for the purification of camellia oil, which could be an effective way to achieve the purification of camellia oil.
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Joshi, Ritika, Nilay Sebat, Kai Chi, Madani Khan, Ken I. Johnson, Abdulrahman G. Alhamzani, M. A. Habib, Tom Lindstrom e Benjamin S. Hsiao. "Low Fouling Nanostructured Cellulose Membranes for Ultrafiltration in Wastewater Treatment". Membranes 13, n.º 2 (23 de janeiro de 2023): 147. http://dx.doi.org/10.3390/membranes13020147.
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Ultrafiltration (UF) is a common technique used in wastewater treatments. However, the issue of membrane fouling in UF can greatly hinder the effectiveness of the treatments. This study demonstrated a low-fouling composite cellulose membrane system based on microfibrillated cellulose (MFC) and silica nanoparticle additives. The incorporation of ‘non-spherical’ silica nanoparticles was found to exhibit better structural integration in the membrane (i.e., minimal aggregation of silica nanoparticles in the membrane scaffold) as compared to spherical silica. The resulting composite membranes were tested for UF using local wastewater, where the best-performing membrane exhibited higher permeation flux than commercial polyvinylidene difluoride (PVDF) and polyether sulfone (PES) membranes while maintaining a high separation efficiency (~99.6%) and good flux recovery ratio (>90%). The analysis of the fouling behavior using different models suggested that the processes of cake layer formation and pore-constriction were probably two dominant fouling mechanisms, likely due to the presence of humic substances in wastewater. The demonstrated cellulose composite membrane system showed low-fouling and high restoration capability by a simple hydraulic cleaning method due to the super hydrophilic nature of the cellulose scaffold containing silica nanoparticles.
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Zhao, Yang, e Liang Duan. "Research on Measuring Pure Membrane Electrical Resistance under the Effects of Salinity Gradients and Diffusion Boundary Layer and Double Layer Resistances". Membranes 12, n.º 8 (22 de agosto de 2022): 816. http://dx.doi.org/10.3390/membranes12080816.
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Forward osmosis membranes are an emerging technology with great potential applicability in energy-efficient wastewater treatments and the differentiation between two solutions. Such solutions often differ in their concentrations or compositions. In this study, the membrane electrical resistances of three different membranes, including cation or anion-exchange membranes and forward osmosis membranes, were analyzed by Luggin capillary coupled with AC impedance spectroscopy (EIS) so as to obtain the real membrane and ion transfer impedance values near the membrane interface. The results reveal that the membrane impedance obtained by both the DC and AC approaches decreased as the lowest external solution concentration increased. Furthermore, the relationship between the membrane conductivity and the internal salt solution concentration was also investigated. It can be seen that the external ion concentration is directly proportional to the free ion concentration in the membrane, and the free ion concentration in the membrane is closely related to the membrane electrical resistance.
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Sakai, Kiyotaka. "History of Hemodialysis Treatments - From DeviceEngineering Points of View -". MEMBRANE 37, n.º 1 (2012): 2–9. http://dx.doi.org/10.5360/membrane.37.2.
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Sallakhniknezhad, Reza, Manijeh Khorsi, Ali Sallakh Niknejad, Saeed Bazgir, Ali Kargari, Mohsen Sazegar, Mohsen Rasouli e Soryong Chae. "Enhancement of Physical Characteristics of Styrene–Acrylonitrile Nanofiber Membranes Using Various Post-Treatments for Membrane Distillation". Membranes 11, n.º 12 (9 de dezembro de 2021): 969. http://dx.doi.org/10.3390/membranes11120969.
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Insufficient mechanical strength and wide pore size distribution of nanofibrous membranes are the key hindrances for their concrete applications in membrane distillation. In this work, various post-treatment methods such as dilute solvent welding, vapor welding, and cold-/hot-pressing processes were used to enhance the physical properties of styrene–acrylonitrile (SAN) nanofiber membranes fabricated by the modified electrospinning process. The effects of injection rate of welding solution and a working distance during the welding process with air-assisted spraying on characteristics of SAN nanofiber membranes were investigated. The welding process was made less time-consuming by optimizing system parameters of the electroblowing process to simultaneously exploit residual solvents of fibers and hot solvent vapor to reduce exposure time. As a result, the welded SAN membranes showed considerable enhancement in mechanical robustness and membrane integrity with a negligible reduction in surface hydrophobicity. The hot-pressed SAN membranes obtained the highest mechanical strength and smallest mean pore size. The modified SAN membranes were used for the desalination of synthetic seawater in a direct contact membrane distillation (DCMD). As a result, it was found that the modified SAN membranes performed well (>99.9% removal of salts) for desalination of synthetic seawater (35 g/L NaCl) during 30 h operation without membrane wetting. The cold-/hot-pressing processes were able to improve mechanical strength and boost liquid entry pressure (LEP) of water. In contrast, the welding processes were preferred to increase membrane flexibility and permeation.
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Sánchez-Villalba, Esther, María Elena Arias, Fabiola Zambrano, Pía Loren e Ricardo Felmer. "Improved exogenous DNA uptake in bovine spermatozoa and gene expression in embryos using membrane destabilizing agents in ICSI-SMGT". Zygote 26, n.º 1 (15 de janeiro de 2018): 104–9. http://dx.doi.org/10.1017/s0967199417000727.
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SummarySperm-mediated gene transfer (SMGT) is a simple, fast, and economical biotechnological tool for producing transgenic animals. However, transgene expression with this technique in bovine embryos is still inefficient due to low uptake and binding of exogenous DNA in spermatozoa. The present study evaluated the effects of sperm membrane destabilization on the binding capacity, location and quantity of bound exogenous DNA in cryopreserved bovine spermatozoa using Triton X-100 (TX-100), lysolecithin (LL) and sodium hydroxide (NaOH). Effects of these treatments were also evaluated by intracytoplasmic sperm injection (ICSI)-SMGT. Results showed that all treatments bound exogenous DNA to spermatozoa including the control. Spermatozoa treated with different membrane destabilizing agents bound the exogenous DNA throughout the head and tail of spermatozoa, compared with the control, in which binding occurred mainly in the post-acrosomal region and tail. The amount of exogenous DNA bound to spermatozoa was much higher for the different sperm treatments than the control (P < 0.05), most likely due to the damage induced by these treatments to the plasma and acrosomal membranes. Exogenous gene expression in embryos was also improved by these treatments. These results demonstrated that sperm membrane destabilization could be a novel strategy in bovine SMGT protocols for the generation of transgenic embryos by ICSI.
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Kennedy, Deirdre, Ultan P. Cronin e Martin G. Wilkinson. "Responses of Escherichia coli, Listeria monocytogenes, and Staphylococcus aureus to Simulated Food Processing Treatments, Determined Using Fluorescence-Activated Cell Sorting and Plate Counting". Applied and Environmental Microbiology 77, n.º 13 (20 de maio de 2011): 4657–68. http://dx.doi.org/10.1128/aem.00323-11.
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ABSTRACTThree common food pathogenic microorganisms were exposed to treatments simulating those used in food processing. Treated cell suspensions were then analyzed for reduction in growth by plate counting. Flow cytometry (FCM) and fluorescence-activated cell sorting (FACS) were carried out on treated cells stained for membrane integrity (Syto 9/propidium iodide) or the presence of membrane potential [DiOC2(3)]. For each microbial species, representative cells from various subpopulations detected by FCM were sorted onto selective and nonselective agar and evaluated for growth and recovery rates. In general, treatments giving rise to the highest reductions in counts also had the greatest effects on cell membrane integrity and membrane potential. Overall, treatments that impacted cell membrane permeability did not necessarily have a comparable effect on membrane potential. In addition, some bacterial species with extensively damaged membranes, as detected by FCM, appeared to be able to replicate and grow after sorting. Growth of sorted cells from various subpopulations was not always reflected in plate counts, and in some cases the staining protocol may have rendered cells unculturable. Optimized FCM protocols generated a greater insight into the extent of the heterogeneous bacterial population responses to food control measures than did plate counts. This study underlined the requirement to use FACS to relate various cytometric profiles generated by various staining protocols with the ability of cells to grow on microbial agar plates. Such information is a prerequisite for more-widespread adoption of FCM as a routine microbiological analytical technique.
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Harder, T., R. Kellner, R. G. Parton e J. Gruenberg. "Specific release of membrane-bound annexin II and cortical cytoskeletal elements by sequestration of membrane cholesterol." Molecular Biology of the Cell 8, n.º 3 (março de 1997): 533–45. http://dx.doi.org/10.1091/mbc.8.3.533.
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Annexin II is an abundant protein which is present in the cytosol and on the cytoplasmic face of plasma membrane and early endosomes. It is generally believed that this association occurs via Ca(2+)-dependent binding to lipids, a mechanism typical for the annexin protein family. Although previous studies have shown that annexin II is involved in early endosome dynamics and organization, the precise biological role of the protein is unknown. In this study, we found that approximately 50% of the total cellular annexin was associated with membranes in a Ca(2+)-independent manner. This binding was extremely tight, since it resisted high salt and, to some extent, high pH treatments. We found, however, that membrane-associated annexin II could be quantitatively released by low concentrations of the cholesterol-sequestering agents filipin and digitonin. Both treatments released an identical and limited set of proteins but had no effects on other membrane-associated proteins. Among the released proteins, we identified, in addition to annexin II itself, the cortical cytoskeletal proteins alpha-actinin, ezrin and moesin, and membrane-associated actin. Our biochemical and immunological observations indicate that these proteins are part of a complex containing annexin II and that stability of the complex is sensitive to cholesterol sequestering agents. Since annexin II is tightly membrane-associated in a cholesterol-dependent manner, and since it seems to interact physically with elements of the cortical actin cytoskeleton, we propose that the protein serves as interface between membranes containing high amounts of cholesterol and the actin cytoskeleton.
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Chen, Kai, Xue Li, Hongyan Zhu, Qiyong Gong e Kui Luo. "Endocytosis of Nanoscale Systems for Cancer Treatments". Current Medicinal Chemistry 25, n.º 25 (30 de agosto de 2018): 3017–35. http://dx.doi.org/10.2174/0929867324666170428153056.
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Advances in nanoscale systems for cancer treatment have been involved in enabling highly regulated site-specific localization to sub cellular organelles hidden beneath cell membranes. So far, the cellular entry of these nanoscale systems has not been fully understood. Endocytosis is an energy-dependent process of active transport in which elected extracellular molecules (such as proteins, viruses, micro-organisms and nanoscale systems) are engulfed into the cell. This process appears at the plasma membrane surface and contains internalization of the cell membrane as well as the membrane proteins and lipids of cell. There are multiform pathways of endocytosis for nanoscale systems. Further comprehension of the mechanisms of endocytosis is achieved with a combination of efficient genetic manipulations, cell dynamic imaging and chemical endocytosis inhibitors. This review provides an account of various endocytic pathways, itemizes current methods to study endocytosis of nanoscale systems, discusses some factors associated with cellular uptake for nanoscale systems and introduces the trafficking behavior for nanoscale systems with active targeting. An insight into the endocytosis mechanism is urgent and significant for developing safe and efficient nanoscale systems for cancer diagnosis and therapy.
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Nagappan, Subbiah, David Phinney e Dennis Heldman. "Management of Waste Streams from Dairy Manufacturing Operations Using Membrane Filtration and Dissolved Air Flotation". Applied Sciences 8, n.º 12 (19 de dezembro de 2018): 2694. http://dx.doi.org/10.3390/app8122694.
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Membrane filtration can provide a significant role in the management of waste streams from food manufacturing operations. The objective of this research was to evaluate the reductions in the organic content of waste streams accomplished when using membrane filtration. Reductions in Chemical Oxygen Demand (COD) by membrane filtration were compared to a Dissolved Air Floatation (DAF) system. Membranes with six different pore sizes (200, 20, 8, 4, 0.083, and 0.058 kDa) were evaluated. In addition, the various membrane treatments were applied after the DAF as an additional level of comparison. The DAF treatment provided 75.15 ± 3.95% reduction in COD, and the reduction in COD improved from 85% to 99% as the membrane pore size decreased. When all membranes were used after a DAF pre-treatment, a reduction in COD to less than 1200 ppm in the permeate stream was achieved. These reductions were independent of the COD in the feed stream. The membrane fouling rates were evaluated for the membranes with the four largest pore-sizes membranes. The membranes with 20 kDa pore-size had the lowest fouling rates during extended fouling-rate studies.
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Selim, Asmaa, Gábor Pál Szijjártó e András Tompos. "Insights into the Influence of Different Pre-Treatments on Physicochemical Properties of Nafion XL Membrane and Fuel Cell Performance". Polymers 14, n.º 16 (18 de agosto de 2022): 3385. http://dx.doi.org/10.3390/polym14163385.
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Perfluorosulfonic acid (PFSA) polymers such as Nafion are the most frequently used Proton Exchange Membrane (PEM) in PEM fuel cells. Nafion XL is one of the most recently developed membranes designed to enhance performance by employing a mechanically reinforced layer in the architecture and a chemical stabilizer. The influence of the water and acid pre-treatment process on the physicochemical properties of Nafion XL membrane and Membrane Electrode Assembly (MEA) was investigated. The obtained results indicate that the pre-treated membranes have higher water uptake and dimensional swelling ratios, i.e., higher hydrophilicity, while the untreated membrane demonstrated a higher ionic exchange capacity. Furthermore, the conductivity of the acid pre-treated Nafion XL membrane was ~ 9.7% higher compared to the untreated membrane. Additionally, the maximum power densities obtained at 80 °C using acid pre-treatment were ~ 0.8 and 0.93 W/cm2 for re-cast Nafion and Nafion XL, respectively. However, the maximum generated powers for untreated membranes at the same condition were 0.36 and 0.66 W/cm2 for re-cast Nafion and Nafion XL, respectively. The overall results indicated that the PEM’s pre-treatment process is essential to enhance performance.
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Charcosset, Catherine. "A Review on Membranes for Clinical Treatment and Drug Delivery in Medical Applications". International Journal of Membrane Science and Technology 3, n.º 1 (31 de maio de 2016): 22–38. http://dx.doi.org/10.15379/ijmst.v3i1.579.
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Membrane processes are used extensively in biomedical applications. This state of the art review presents the main applications including renal kidney, blood filtration, blood oxygenator, artificial liver, artificial pancreas, and drug delivery devices. For well-established treatments like dialysis, plasmapheresis, and blood oxygenator, the techniques are summarized by presenting membranes used, devices, configurations and treatments. The artificial liver and the artificial pancreas are not clinically used and some main aspects related to the development of these devices are given, including configurations and liver or pancreatic cells. Finally, drug delivery devices based on membranes, which are an important area in pharmaceutics, are summarized by focusing on diffusion and transdermal delivery systems, as well as colloids like liposomes and nanocapsules. These colloids with nanometric size are surrounded by a lipidic or polymeric thin membrane which controls drug transfer to the surrounding medium.
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Liu, Yu-Jing, Yan-Nan Lu, Dong-Qing Liang, Yin-Shuang Hu e Yu-Xi Huang. "Multi-Layered Branched Surface Fluorination on PVDF Membrane for Anti-Scaling Membrane Distillation". Membranes 12, n.º 8 (29 de julho de 2022): 743. http://dx.doi.org/10.3390/membranes12080743.
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Membrane distillation (MD) has emerged as a promising technology for hypersaline wastewater treatment. However, membrane scaling is still a critical issue for common hydrophobic MD membranes. Herein, we report a multi-layered surface modification strategy on the commercial polyvinylidene fluoride (PVDF) membrane via plasma treatment and surface fluorination cycles. The repeated plasma treatment process generates more reaction sites for the fluorination reaction, leading to higher fluorination density and more branched structures. MD tests with CaSO4 as the scaling agent show that the modification strategy mentioned above improves the membrane scaling resistance. Notably, the PVDF membrane treated with three cycles of plasma and fluorination treatments exhibits the best anti-scaling performance while maintaining almost the same membrane flux as the unmodified PVDF membrane. This study suggests that a highly branched surface molecular structure with low surface energy benefits the MD process in both membrane flux and scaling resistance. Besides, our research demonstrates a universal and facile approach for membrane treatment to improve membrane scaling resistance.
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Okoro, Emmanuel E., Rachael Josephs, Samuel E. Sanni e Yuven Nchila. "Advances in the Use of Nanocomposite Membranes for Carbon Capture Operations". International Journal of Chemical Engineering 2021 (18 de junho de 2021): 1–22. http://dx.doi.org/10.1155/2021/6666242.
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The adoption of nanodoped membranes in the areas of gas stream separation, water, and wastewater treatments due to the physical and operational advantages of such membranes has significantly increased. The literature has shown that the surface structure and physicochemical properties of nanodoped membranes contribute significantly to the interaction and rejection characteristics when compared to bare membranes. This study reviews the recent developments on nanodoped membranes, and their hybrids for carbon capture and gas separation operations. Features such as the nanoparticles/materials and hybrids used for membrane doping and the effect of physicochemical properties and water vapour in nanodoped membrane performance for carbon capture are discussed. The highlights of this review show that nanodoped membrane is a facile modification technique which improves the membrane performance in most cases and holds a great potential for carbon capture. Membrane module design and material, thickness, structure, and configuration were identified as key factors that contribute directly, to nanodoped membrane performance. This study also affirms that the three core parameters satisfied before turning a microporous material into a membrane are as follows: high permeability and selectivity, ease of fabrication, and robust structure. From the findings, it is also observed that the application of smart models and knowledge-based systems have not been extensively studied in nanoparticle-/material-doped membranes. More studies are encouraged because technical improvements are needed in order to achieve high performance of carbon capture using nanodoped membranes, as well as improving their durability, permeability, and selectivity of the membrane.
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Reig, Mònica, Xanel Vecino e José Luis Cortina. "Use of Membrane Technologies in Dairy Industry: An Overview". Foods 10, n.º 11 (11 de novembro de 2021): 2768. http://dx.doi.org/10.3390/foods10112768.
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The use of treatments of segregated process streams as a water source, as well as technical fluid reuse as a source of value-added recovery products, is an emerging direction of resource recovery in several applications. Apart from the desired final product obtained in agro-food industries, one of the challenges is the recovery or separation of intermediate and/or secondary metabolites with high-added-value compounds (e.g., whey protein). In this way, processes based on membranes, such as microfiltration (MF), ultrafiltration (UF), nanofiltration (NF) and reverse osmosis (RO), could be integrated to treat these agro-industrial streams, such as milk and cheese whey. Therefore, the industrial application of membrane technologies in some processing stages could be a solution, replacing traditional processes or adding them into existing treatments. Therefore, greater efficiency, yield enhancement, energy or capital expenditure reduction or even an increase in sustainability by producing less waste, as well as by-product recovery and valorization opportunities, could be possible, in line with industrial symbiosis and circular economy principles. The maturity of membrane technologies in the dairy industry was analyzed for the possible integration options of membrane processes in their filtration treatment. The reported studies and developments showed a wide window of possible applications for membrane technologies in dairy industry treatments. Therefore, the integration of membrane processes into traditional processing schemes is presented in this work. Overall, it could be highlighted that membrane providers and agro-industries will continue with a gradual implementation of membrane technology integration in the production processes, referring to the progress reported on both the scientific literature and industrial solutions commercialized.
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Hamada, Toyozo, Yasumitsu Miyazaki e Yoshiki Kinoshita. "Reuse System for Car Wash Water by Flocculation, Ultrafiltration and Activated Carbon Treatments". membrane 29, n.º 1 (2004): 73–76. http://dx.doi.org/10.5360/membrane.29.73.
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Lee, Sungsu, Han Yen Tan, Ivayla I. Geneva, Aleksandr Kruglov e Peter D. Calvert. "Actin filaments partition primary cilia membranes into distinct fluid corrals". Journal of Cell Biology 217, n.º 8 (26 de junho de 2018): 2831–49. http://dx.doi.org/10.1083/jcb.201711104.
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Physical properties of primary cilia membranes in living cells were examined using two independent, high-spatiotemporal-resolution approaches: fast tracking of single quantum dot–labeled G protein–coupled receptors and a novel two-photon super-resolution fluorescence recovery after photobleaching of protein ensemble. Both approaches demonstrated the cilium membrane to be partitioned into corralled domains spanning 274 ± 20 nm, within which the receptors are transiently confined for 0.71 ± 0.09 s. The mean membrane diffusion coefficient within the corrals, Dm1 = 2.9 ± 0.41 µm2/s, showed that the ciliary membranes were among the most fluid encountered. At longer times, the apparent membrane diffusion coefficient, Dm2 = 0.23 ± 0.05 µm2/s, showed that corral boundaries impeded receptor diffusion 13-fold. Mathematical simulations predict the probability of G protein–coupled receptors crossing corral boundaries to be 1 in 472. Remarkably, latrunculin A, cytochalasin D, and jasplakinolide treatments altered the corral permeability. Ciliary membranes are thus partitioned into highly fluid membrane nanodomains that are delimited by filamentous actin.
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Touze-Soulet, J. M., J. D. Weete, M. Sancholle, J. Rami e R. Dargent. "Influence of biotin on the lipid composition of plasma membranes from Hypomyces chlorinus". Biochemistry and Cell Biology 68, n.º 1 (1 de janeiro de 1990): 138–44. http://dx.doi.org/10.1139/o90-018.
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Subfractions of microsomal membranes from the biotin heteroauxotroph Hypomyces chlorinus Tul., cultured in media containing optimal or suboptimal levels of the vitamin, were isolated using a two-phase polymer system and characterized as plasma membrane-enriched on the basis of absence of Zn2+-induced aggregation, enrichment of appropriate enzyme markers, and phosphotungstic acid – chromic acid staining. The protein/lipid ratio of membranes from the biotin-sufficient and -deficient cultures was 2; the phospholipid content was 126 and 181 μg/mg protein; and the sterol/phospholipid molar ratios were 0.38 and 0.16, respectively, with ergosterol as the predominant sterol. The lipids were qualitatively similar in the plasma membrane fractions from the two treatments. Ergosterol content of the membrane fractions from mycelium cultured in low biotin medium was 40–100% less than that from the corresponding biotin-sufficient cultures. A nonphosphorus glycolipid was the predominant lipid of the plasma membranes from both treatments.Key words: Hypomyces, plasma membrane, sterols, biotin deficiency, ergosterol.
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Ji, Zuohui, Yue Zhao, Min Zhang, Xiaopeng Li e Heguo Li. "Surface Modification of ETFE Membrane and PTFE Membrane by Atmospheric DBD Plasma". Membranes 12, n.º 5 (10 de maio de 2022): 510. http://dx.doi.org/10.3390/membranes12050510.
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Fluorine resin membranes with excellent chemical resistance have great potential for the application of high-performance chemical protective clothing. However, it is difficult to integrate fluorine resins into other materials such as fabrics due to their lower surface energy and poor bondability, making the fabrication of composite fabrics and the further seal splicing challenging. In this study, atmospheric pressure dielectric barrier discharge (DBD) plasma in helium (He) and helium/acrylic acid (He/AA) mixture atmospheres were used to modify two kinds of fluorine resins, ethylene tetrafluoroethylene (ETFE) and polytetrafluoroethylene (PTFE) membrane. The surface chemical properties, physical morphology, hydrophilicity and adhesion strength of the fluororesin membranes before and after plasma treatments were systematically analyzed. The results showed that the plasma treatment can modify the membrane surface at the nanoscale level without damaging the main body of the membrane. The hydrophilicity of the plasma-treated membrane was improved with the water contact angle decreasing from 95.83° to 49.9° for the ETFE membrane and from 109.9° to 67.8° for the PTFE membrane, respectively. The He plasma creates active sites on the membrane surface as well as etching the membrane surface, increasing the surface roughness. The He/AA plasma treatment introduces two types of polyacrylic acid (PAA)—deposited polyacrylic acid (d-PAA) and grafted polyacrylic acid (g-PAA)—on the membrane surface. Even after ultrasonic washing with acetone, g-PAA still existed stably and, as a result, improved the polarity and adhesion strength of fluororesin membranes. This work provides useful insights into the modification mechanism of DBD plasma on fluorine resins, with implications for developing effective strategies of integrating fluorine resin membrane to chemical protective clothing fabrics.
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Li, Shufeng, Xuelin Li, Pengfei Fu e Yao Zhang. "Alkali-Grafting Proton Exchange Membranes Based on Co-Grafting of α-Methylstyrene and Acrylonitrile into PVDF". Polymers 14, n.º 12 (15 de junho de 2022): 2424. http://dx.doi.org/10.3390/polym14122424.
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A novel alkali-induced grafting polymerization was designed to synthesize a PFGPA proton exchange membrane based on the co-grafting of α-methyl styrene (AMS) and acrylonitrile (AN) into the poly(vinylidenedifluoride) (PVDF) membrane. Three kinds of alkali treatments were used: by immersing the PVDF membranes into a 1 M NaOH solution and mixing the PVDF powders with 16% or 20% Na4SiO4. Then, AMS with AN could be co-grafted into the PVDF backbones in two grafting solvents, THF or IPA/water. Finally, the grafted membranes were sulfonated to provide the PFGPA membranes. In the experiments, the Na4SiO4 treatments showed a greater grafting degree than the NaOH treatment. The grafting degree increased with the increasing amount of Na4SiO4. The grafting solvent also influenced the grafting degree. A 40–50 percent grafting degree was obtained in either the THF or IPA/water solvent after the Na4SiO4 treatment and the THF resulted in a greater grafting degree. FTIR and XPS testified that the PFGPA membranes had been prepared and a partial hydrolysis of the cyano group from AN occurred. The PFGPA membranes with the grafting degree of about 40–50 percent showed a better dimensional stability in methanol, greater water uptake capabilities, and lower ion exchange capacities and conductivities than the Nafion 117 membranes. The PFGPA membrane with the 16% Na4SiO4 treatment and THF as the grafting solvent exhibited a better chemical stability. The obtained experimental results will provide a guide for the synthesis of alkali-grafted PFGPA membranes in practical use.
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Kertész, Szabolcs, Aws N. Al-Tayawi, Gréta Gergely, Bence Ott, Nikolett Sz Gulyás, Zoltán Jákói, Sándor Beszédes, Cecilia Hodúr, Tamás Szabó e Zsuzsanna László. "Investigation of Different Pre-Treatment Techniques and 3D Printed Turbulence Promoter to Mitigate Membrane Fouling in Dairy Wastewater Module". Materials 16, n.º 8 (15 de abril de 2023): 3117. http://dx.doi.org/10.3390/ma16083117.
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This study investigates the enhancement of dairy wastewater treatment using chemical and physical pre-treatments coupled with membrane separation techniques to reduce membrane fouling. Two mathematical models, namely the Hermia and resistance-in-series module, were utilized to comprehend the mechanisms of ultrafiltration (UF) membrane fouling. The predominant fouling mechanism was identified by fitting experimental data into four models. The study calculated and compared permeate flux, membrane rejection, and membrane reversible and irreversible resistance values. The gas formation was also evaluated as a post-treatment. The results showed that the pre-treatments improved UF efficiency for flux, retention, and resistance values compared to the control. Chemical pre-treatment was identified as the most effective approach to improve filtration efficiency. Physical treatments after microfiltration (MF) and UF showed better fluxes, retention, and resistance results than ultrasonic pre-treatment followed by UF. The efficacy of a three-dimensionally printed (3DP) turbulence promoter was also examined to mitigate membrane fouling. The integration of the 3DP turbulence promoter enhanced hydrodynamic conditions and increased the shear rate on the membrane surface, shortening filtration time and increasing permeate flux values. This study provides valuable insights into optimizing dairy wastewater treatment and membrane separation techniques, which can have significant implications for sustainable water resource management. The present outcomes clearly recommend the application of hybrid pre-, main- and post-treatments coupled with module-integrated turbulence promoters in dairy wastewater ultrafiltration membrane modules to increase membrane separation efficiencies.
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Sampathkumar, Balamurugan, George G. Khachatourians e Darren R. Korber. "High pH during Trisodium Phosphate Treatment Causes Membrane Damage and Destruction of Salmonella enterica Serovar Enteritidis". Applied and Environmental Microbiology 69, n.º 1 (janeiro de 2003): 122–29. http://dx.doi.org/10.1128/aem.69.1.122-129.2003.
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ABSTRACT Trisodium phosphate (TSP) is now widely used during the processing of poultry and red meats, but the mechanism whereby it inactivates gram-negative bacteria such Salmonella spp. remains unclear. Thus, Salmonella enterica serovar Enteritidis (ATCC 4931) cells were treated with different concentrations of TSP (1.5, 2.0, and 2.5% [wt/vol]) and compared with (i) cells treated with the same pH as the TSP treatments (pH 10.0, 10.5, and 11.0, respectively) and (ii) cells treated with different concentrations of TSP (1.5, 2.0, and 2.5% [wt/vol]) adjusted to a pH of 7.0 ± 0.2 (mean ± standard deviation). Cell viability, loss of membrane integrity, cellular leakage, release of lipopolysaccharides, and cell morphology were accordingly examined and quantified under the above treatment conditions. Exposure of serovar Enteritidis cells to TSP or equivalent alkaline pH resulted in the loss of cell viability and membrane integrity in a TSP concentration- or alkaline pH-dependent manner. In contrast, cells treated with different concentrations of TSP whose pH was adjusted to 7.0 did not show any loss of cell viability or membrane integrity. A 30-min pretreatment with 1.0 mM EDTA significantly enhanced the loss of membrane integrity only when followed by TSP or alkaline pH treatments. Measuring the absorbance at 260 nm, agarose gel electrophoresis, Bradford assay, and Tricine-sodium dodecyl sulfate gel electrophoresis of filtrates of treated cell suspensions revealed considerable release of DNA, proteins, and lipopolysaccharides compared to controls and pH 7.0 TSP treatments. Electron microscopic examination of TSP- or alkaline pH-treated cells showed disfigured cell surface topology and wrinkled appearance and showed evidence of a TSP concentration- and pH-dependent disruption of the cytoplasmic and outer membranes. These results demonstrate that TSP treatment permeabilizes and disrupts the cytoplasmic and outer membranes of serovar Enteritidis cells because of the alkaline pH, which in turn leads to release of intracellular contents and eventual cell death.
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Dwi Jayanti, Denik, Asnawati Asnawati, Dwi Indarti, Donatus S. Purwo Handoko e Bambang Piluharto. "Effect of pH in Coagulation Bath on Polysulfone-based Membrane Formation and Its Performance Characteristics". Indonesian Chimica Letters 1, n.º 1 (17 de junho de 2022): 13–16. http://dx.doi.org/10.19184/icl.v1i1.6.
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One of the factors that determine the formation of the membrane is the solution in the coagulation bath (non-solvent). In this study, the effect of pH treatment on the coagulation bath solution on membrane formation and its effect on membrane performance will be studied. The pH of the coagulation bath used was pH 1, 6.8 and 12. As the results, physically the three pH treatments produced the same white (opaque) membrane. Through morphological analysis, it appears that the three pH treatments produced an asymmetric membrane consisting of a top layer and a sublayer. The surface of the membrane with pH 1 treatment showed a denser surface than the pH 6.8 and pH 12 treatments. The results of the membrane performance characterization showed that the membrane permeability coefficient of the membrane with pH treatment was in the following order pH 1 < pH 12 < pH 6.8. While the value of the rejection coefficient showed that the membrane treated at pH 1 did not detect rejection because there was no permeate coming out, while at the treatment at pH 6.8 and 12, the rejection coefficient values were 74% and 76%, respectively.
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Diena, Nurin Nisa Farah, Mahmud Mahmud, Rony Riduan e Ahmad Kurnain. "Performance of Activated Carbon Adsorption and Ultrafiltration Membrane Hybrid Process for Leachate Treatment". TROPICAL WETLAND JOURNAL 4, n.º 1 (17 de julho de 2018): 17–20. http://dx.doi.org/10.20527/twj.v4i1.58.
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Leachate is wastewater that contains pollutants dominated by organic matter. Conventional leachate treatments have some disadvantages therefore alternative treatments are needed. One of that alternative treatments is ultrafiltration membrane and adsorption as pretreatment. The aims of this study are to analyze adsorption isotherm and kinetic model for UV254 (UV adsorbance at 254 nm wavelength) adsorption, the performance of powdered activated carbon (PAC) adsorption and ultrafiltration membrane hybrid process for UV254 of leachate removal, and the effect of pretreatment towards membrane fouling. The result of this study are Freundlich isotherm and pseudo second order kinetic model best fitted model for ultrafiltration membrane hybrid process condition for UV254 removal level are at pH 6; 120 minutes contact time; and 4 g/L PAC doses. Adsorption as pretreatment can reduce membrane ultrafiltration fouling.
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Alshahrani, Ahmed A., Abeer A. El-Habeeb, Arwa A. Almutairi, Dimah A. Almuaither, Sara A. Abudajeen, Hassan M. A. Hassan e Ibrahim Hotan Alsohaimi. "Preparation, Characterization and Evaluation of Polyamide-Reduced Graphene Oxide as Selective Membranes for Water Purification". Journal of Composites Science 8, n.º 1 (10 de janeiro de 2024): 24. http://dx.doi.org/10.3390/jcs8010024.
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Amidst the ongoing advancements in membrane technology, a leading method has come to the forefront. Recent research has emphasized the substantial influence of surface attributes in augmenting the effectiveness of thin-film membranes in water treatments. These studies reveal how surface properties play a crucial role in optimizing the performance of these membranes, further establishing their prominence in the field of membrane technology. This recognition stems from the precise engineering of surfaces, ensuring they meet the demanding requirements of advanced separation processes. This study utilizes polyamide as a discerning layer, applied atop a polysulfone support sheet through interfacial polymerization (IP) for membrane fabrication. The amounts in the various membranes were created to vary. The membrane’s permeability to water with significant salt rejection was enhanced, which improved its effectiveness. The polyamide (PA) membrane comprising graphene oxide (rGO, 0.015%) had a water permeability of 48.90 L/m2 h at 22 bar, which was much higher than the mean permeability of polyamide membranes (25.0 L/m2 h at 22 bar). On the other hand, the PA–rGO/CHIT membranes exhibited the lowest water permeability due to their decreased surface roughness. However, the membranes’ effectiveness in rejecting salts ranged from 80% to 95% for PA–rGO and PA–rGO/CHIT membranes.
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Nauman, Saad, Gilles Lubineau e Hamad F. Alharbi. "Post Processing Strategies for the Enhancement of Mechanical Properties of ENMs (Electrospun Nanofibrous Membranes): A Review". Membranes 11, n.º 1 (5 de janeiro de 2021): 39. http://dx.doi.org/10.3390/membranes11010039.
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Electrospinning is a versatile technique which results in the formation of a fine web of fibers. The mechanical properties of electrospun fibers depend on the choice of solution constituents, processing parameters, environmental conditions, and collector design. Once electrospun, the fibrous web has little mechanical integrity and needs post fabrication treatments for enhancing its mechanical properties. The treatment strategies include both the chemical and physical techniques. The effect of these post fabrication treatments on the properties of electrospun membranes can be assessed through either conducting tests on extracted single fiber specimens or macro scale testing on membrane specimens. The latter scenario is more common in the literature due to its simplicity and low cost. In this review, a detailed literature survey of post fabrication strength enhancement strategies adopted for electrospun membranes has been presented. For optimum effect, enhancement strategies have to be implemented without significant loss to fiber morphology even though fiber diameters, porosity, and pore tortuosity are usually affected. A discussion of these treatments on fiber crystallinity, diameters, and mechanical properties has also been produced. The choice of a particular post fabrication strength enhancement strategy is dictated by the application area intended for the membrane system and permissible changes to the initial fibrous morphology.
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Hajaratul Najwa Mohamed, Norazlina Hashim, Mohamad Shahairy Fahmi Affandi e Meor Najmuddin Meor Suzurudin. "Development and In-vitro Evaluation of Konjac Glucomannan/Virgin Coconut Oil Based Asymmetric Membrane for Wound Dressing". Journal of Advanced Research in Applied Sciences and Engineering Technology 47, n.º 2 (28 de junho de 2024): 138–47. http://dx.doi.org/10.37934/araset.47.2.138147.
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Asymmetric membranes have promising features for use in wound dressings. A permeable bottom layer absorbs the wound exudate, whereas the occlusive top layer restricts microbiological penetration and avoids an excessive loss of water. Recently, asymmetric membranes made of konjac glucomannan (KGM), a natural polysaccharide, have been explored as potential wound treatments. However, there are no studies reported regarding the incorporation of other materials into KGM asymmetric membrane. Due to its biocompatibility and antimicrobial properties, virgin coconut oil (VCO) is a good choice for promoting the healing process. In this study, we examine the potential of using KGM asymmetric membrane with different concentration of VCO as wound dressing material. The membrane sample's asymmetric morphology and good thermal stability were both revealed by scanning electron microscopy and thermogravimetric studies, respectively. In addition, biological and fluid handling capacity analysis indicated that the KGM-VCO membrane is biocompatible and able to maintain the ideal moist environment for wound healing.
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Yan, Zhongsen, Yuling Jiang, Lingshan Liu, Zhongsheng Li, Xiaolei Chen, Mingqian Xia, Gongduan Fan e An Ding. "Membrane Distillation for Wastewater Treatment: A Mini Review". Water 13, n.º 24 (7 de dezembro de 2021): 3480. http://dx.doi.org/10.3390/w13243480.
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Water serves as an indispensable part of human life and production. On account of the overexploitation of traditional water sources, the demand for wastewater recycling is expanding rapidly. As a promising water treatment process, membrane distillation (MD) has been utilized in various wastewater treatments, such as desalination brine, textile wastewater, radioactive wastewater, and oily wastewater. This review summarized the investigation work applying MD in wastewater treatment, and the performance was comprehensively introduced. Moreover, the obstructions of industrialization, such as membrane fouling, membrane wetting, and high energy consumption, were discussed with the practical investigation. To cope with these problems, various strategies have been adopted to enhance MD performance, including coupling membrane processes and developing membranes with specific surface characteristics. In addition, the significance of nutrient recovery and waste heat utilization was indicated.
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Ahmed, Sadiq, e Andre Kaplan. "Therapeutic Plasma Exchange Using Membrane Plasma Separation". Clinical Journal of the American Society of Nephrology 15, n.º 9 (20 de abril de 2020): 1364–70. http://dx.doi.org/10.2215/cjn.12501019.
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Therapeutic plasma exchange is a blood purification technique designed for the removal of large molecular weight toxins such as pathogenic antibodies and lipoproteins. Plasma exchange can be performed either by membrane separation or centrifugation. Centrifugal plasma exchange is more common in the United States, while membrane separation is more popular in Germany and Japan. The membrane separation technique is similar to the ultrafiltration procedures performed with a standard dialysis machine but in which the membrane’s pores are large enough to allow removal of all circulating molecules while retaining the cellular components. The current availability of plasma separation membranes compatible with CRRT systems has dramatically increased the potential for almost all nephrologists to perform these treatments. This review describes the membrane separation techniques available in the United States, the practical aspects of ordering and operating a membrane separation plasma exchange procedure, and its possible complications.
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Nazari, Shayan S., Andrew D. Doyle e Kenneth M. Yamada. "Mechanisms of Basement Membrane Micro-Perforation during Cancer Cell Invasion into a 3D Collagen Gel". Gels 8, n.º 9 (7 de setembro de 2022): 567. http://dx.doi.org/10.3390/gels8090567.
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Cancer invasion through basement membranes represents the initial step of tumor dissemination and metastasis. However, little is known about how human cancer cells breach basement membranes. Here, we used a three-dimensional in vitro invasion model consisting of cancer spheroids encapsulated by a basement membrane and embedded in 3D collagen gels to visualize the early events of cancer invasion by confocal microscopy and live-cell imaging. Human breast cancer cells generated large numbers of basement membrane perforations, or holes, of varying sizes that expanded over time during cell invasion. We used a wide variety of small molecule inhibitors to probe the mechanisms of basement membrane perforation and hole expansion. Protease inhibitor treatment (BB94), led to a 63% decrease in perforation size. After myosin II inhibition (blebbistatin), the basement membrane perforation area decreased by only 15%. These treatments produced correspondingly decreased cellular breaching events. Interestingly, inhibition of actin polymerization dramatically decreased basement membrane perforation by 80% and blocked invasion. Our findings suggest that human cancer cells can primarily use proteolysis and actin polymerization to perforate the BM and to expand perforations for basement membrane breaching with a relatively small contribution from myosin II contractility.
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Darbandi, Fatemeh, Azadeh Mousavi, Tayebe Bagheri Lotfabad, Amir Heydarinasab e Soheila Yaghmaei. "Azo dye removal via surfactant-assisted polyvinylidene fluoride membrane". Environmental Health Engineering and Management 8, n.º 1 (15 de fevereiro de 2021): 25–32. http://dx.doi.org/10.34172/ehem.2021.04.
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Background: Recently, concerns have been raised regarding the environmental and public health safety of azo dyes, the most widely used synthetic dyes. The membrane technique has been introduced as one of the efficient methods for dye removal treatments. Polyvinylidene fluoride (PVDF) membrane manipulated by surfactants was studied for removal of the azo dye, carmoisine. Methods: PVDF membrane was prepared via non-solvent-induced phase separation (NIPS) and used to remove the azo dye, carmoisine. Three nonionic surfactants including Tween 20, Tween 60, and Tween 80 were used individually as additives in casting solutions to improve PVDF membrane properties. Results: Fourier-transform infrared spectroscopy (FTIR) demonstrated the presence of functional groups of carbonyl (C=O) and hydroxyl (OH), assigned to Tween molecules, in the membrane chemical structure. All Tween species caused a decrease in the surface hydrophobicity of PVDF membranes illustrated by the reduced contact angles. Each Tween at a 2% concentration in the dope solution led to an increase in the pore-size of PVDF membranes, which was estimated by scanning electron microscopy (SEM). However, this impact was reversed at Tween concentrations of 4%. Membranes were assessed for dye removal efficiency and permeate flux in a cross-flow system. Permeability of PVDF membranes improved (~78%) with adding Tween 80 at a concentration of 2%. Tween 60 at a 2% concentration resulted in a ~45% increase in dye removal efficiency of PVDF membranes. And, atomic force microscopy (AFM) showed that Tween 60 increased membrane surface roughness. Conclusion: Surfactant-mediated changes in the surface properties of PVDF membrane improved dye removal efficacy.
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Nakanishi, Yoichiro, Shuichi Asakura e Akio Fuwa. "Hydrophilic Treatments of Polysulfone Microfiltration Membrane Based on Plasma Graft Polymerization for Inhibition of Protein Adsorption". MEMBRANE 30, n.º 3 (2005): 165–70. http://dx.doi.org/10.5360/membrane.30.165.
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Cameron, R. S., P. L. Cameron e J. D. Castle. "A common spectrum of polypeptides occurs in secretion granule membranes of different exocrine glands." Journal of Cell Biology 103, n.º 4 (1 de outubro de 1986): 1299–313. http://dx.doi.org/10.1083/jcb.103.4.1299.
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A highly purified membrane preparation from rat parotid secretion granules has been used as a comparative probe to examine the extent of compositional overlap in granule membranes of three other exocrine secretory tissues--pancreatic, lacrimal, and submandibular--from several standpoints. First, indirect immunofluorescent studies using a polyclonal polyspecific anti-parotid granule membrane antiserum has indicated a selective staining of granule membrane profiles in all acinar cells of all tissues. Second, highly purified granule membrane subfractions have been isolated from each exocrine tissue; comparative two-dimensional (isoelectric focusing; SDS) PAGE of radioiodinated granule membranes has identified 10-15 polypeptides of identical pI and apparent molecular mass. These species are likely to be integral membrane components since they are not extracted by either saponin-sodium sulfate or sodium carbonate (pH 11.5) treatments, and they do not have counterparts in the granule content. Finally, the identity among selected parotid and pancreatic radioiodinated granule membrane polypeptides has been documented using two-dimensional peptide mapping of chymotryptic and tryptic digests. These findings clearly indicate that exocrine secretory granules, irrespective of the nature of stored secretion, comprise a type of vesicular carrier with a common (and probably refined) membrane composition. Conceivably, the polypeptides identified carry out general functions related to exocrine secretion.
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Leuschner, Carola, e William Hansel. "Membrane Disrupting Lytic Peptides for Cancer Treatments". Current Pharmaceutical Design 10, n.º 19 (1 de julho de 2004): 2299–310. http://dx.doi.org/10.2174/1381612043383971.
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Fukuda, Makoto, Ryo Tanaka, Kazunori Sadano, Asako Tokumine, Tomohiro Mori, Hitoshi Saomoto e Kiyotaka Sakai. "Insights into Gradient and Anisotropic Pore Structures of Capiox® Gas Exchange Membranes for ECMO: Theoretically Verifying SARS-CoV-2 Permeability". Membranes 12, n.º 3 (10 de março de 2022): 314. http://dx.doi.org/10.3390/membranes12030314.
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When using the extracorporeal capillary membrane oxygenator (sample A) for ECMO treatments of COVID-19 severely ill patients, which is dominantly used in Japan and worldwide, there is a concern about the risk of SARS-CoV-2 scattering from the gas outlet port of the membrane oxygenator. Terumo has launched two types of membranes (sample A and sample B), both of which are produced by the microphase separation processes using polymethylpentene (PMP) and polypropylene (PP), respectively. However, the pore structures of these membranes and the SARS-CoV-2 permeability through the membrane wall have not been clarified. In this study, we analyzed the pore structures of these gas exchange membranes using our previous approach and verified the SARS-CoV-2 permeation through the membrane wall. Both have the unique gradient and anisotropic pore structure which gradually become denser from the inside to the outside of the membrane wall, and the inner and outer surfaces of the membrane have completely different pore structures. The pore structure of sample A is also completely different from the other membrane made by the melt-extruded stretch process. From this, the pore structure of the ECMO membrane is controlled by designing various membrane-forming processes using the appropriate materials. In sample A, water vapor permeates through the coating layer on the outer surface, but no pores that allow SARS-CoV-2 to penetrate are observed. Therefore, it is unlikely that SARS-CoV-2 permeates through the membrane wall and scatter from sample A, raising the possibility of secondary ECMO infection. These results provide new insights into the evolution of a next-generation ECMO membrane.
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Bloch, Daria, Meirav Lavy, Yael Efrat, Idan Efroni, Keren Bracha-Drori, Mohamad Abu-Abied, Einat Sadot e Shaul Yalovsky. "Ectopic Expression of an Activated RAC inArabidopsisDisrupts Membrane Cycling". Molecular Biology of the Cell 16, n.º 4 (abril de 2005): 1913–27. http://dx.doi.org/10.1091/mbc.e04-07-0562.
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Rho GTPases regulate the actin cytoskeleton, exocytosis, endocytosis, and other signaling cascades. Rhos are subdivided into four subfamilies designated Rho, Racs, Cdc42, and a plant-specific group designated RACs/Rops. This research demonstrates that ectopic expression of a constitutive active Arabidopsis RAC, AtRAC10, disrupts actin cytoskeleton organization and membrane cycling. We created transgenic plants expressing either wild-type or constitutive active AtRAC10 fused to the green fluorescent protein. The activated AtRAC10 induced deformation of root hairs and leaf epidermal cells and was primarily localized in Triton X-100–insoluble fractions of the plasma membrane. Actin cytoskeleton reorganization was revealed by creating double transgenic plants expressing activated AtRAC10 and the actin marker YFP-Talin. Plants were further analyzed by membrane staining with N-[3-triethylammoniumpropyl]-4-[p-diethylaminophenylhexatrienyl] pyridinium dibromide (FM4-64) under different treatments, including the protein trafficking inhibitor brefeldin A or the actin-depolymeryzing agents latrunculin-B (Lat-B) and cytochalasin-D (CD). After drug treatments, activated AtRAC10 did not accumulate in brefeldin A compartments, but rather reduced their number and colocalized with FM4-64–labeled membranes in large intracellular vesicles. Furthermore, endocytosis was compromised in root hairs of activated AtRAC10 transgenic plants. FM4-64 was endocytosed in nontransgenic root hairs treated with the actin-stabilizing drug jasplakinolide. These findings suggest complex regulation of membrane cycling by plant RACs.
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Cerio, RJ, F. Xing, RJ Fatula, DE Keith, X. Yang, F. Talamantes, JN Southard e JN Southard. "Structurally distinct membrane-associated and soluble forms of GH-binding protein in the mouse". Journal of Endocrinology 172, n.º 2 (1 de fevereiro de 2002): 321–31. http://dx.doi.org/10.1677/joe.0.1720321.
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It has previously been shown that the large increase in GH-binding capacity of mouse liver microsomes during pregnancy is due largely to an increase in the amount of GH-binding protein (GHBP), with a more modest increase in GH receptor (GHR). Here we show that mouse liver GHBP is predominantly present as a membrane-associated protein structurally distinct from the soluble form of GHBP present in serum. Liver GHBP is associated with both intracellular membranes and the plasma membrane. Membrane-associated GHBP and soluble GHBP appear to be identical polypeptides distinguished by the addition of different N-glycans to asparagine residues. The pattern of release of GHBP from membranes by various treatments indicates that GHBP associates with membranes through noncovalent interactions with one or more membrane protein, but not with GHR. Covalent crosslinking provides evidence for several GHBP-associated membrane polypeptides, with molecular masses ranging from 58 kDa to over 200 kDa. These studies in the mouse and similar studies in the rat suggest that GHBP is an important cell-surface receptor for GH in the liver of these species. We postulate that an arginine-glycine-aspartic acid sequence found on rat and mouse GHBP but absent in other species is responsible for the association of GHBP with the plasma membrane by binding to one or more integrins on the surface of liver cells.
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Susanto, H., e M. Ulbricht. "Highly fouling resistant ultrafiltration membranes for water and wastewater treatments". Water Supply 8, n.º 1 (1 de abril de 2008): 19–24. http://dx.doi.org/10.2166/ws.2008.002.
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Control of fouling is a critical issue to increase the competitiveness of ultrafiltration (UF) membranes for drinking water and wastewater treatments. Highly fouling resistant UF membranes synthesized by photo-graft copolymerization of a water soluble monomer, poly(ethylene glycol) methacrylate (PEGMA), onto a polyethersulfone UF membrane have been evaluated with respect to the adsorptive as well as the ultrafiltration fouling. Protein, humic substance and polysaccharide solutions were used as the model for foulants occurring in the water sources for drinking water as well as in wastewater effluents. The results show that the modified membranes exhibited a much higher fouling resistance for all foulants than the unmodified membranes. Their combined high fouling resistance and high rejection suggests that the obtained modified membranes are very promising as a new generation of thin-layer composite low fouling UF membranes for drinking water and wastewater treatment applications.
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Lyu, Chengqi, Zhengwei Shao, Derong Zou e Jiayu Lu. "Ridge Alterations following Socket Preservation Using a Collagen Membrane in Dogs". BioMed Research International 2020 (4 de março de 2020): 1–9. http://dx.doi.org/10.1155/2020/1487681.
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Background. The healing process following tooth extraction results in alveolar ridge resorption. The dimensional changes may complicate the subsequent implant procedure. Socket preservation using absorbable collagen membranes or a combination of membranes with calcium phosphate cement (CPC) particles might ensure that the alveolar ridge retains a suitable morphology for implant placement. Objective. To evaluate the quality and quantity of new bone regenerated after application of either collagen membranes alone covering the sockets or a combination of membranes with CPC particles added into the sockets in dogs. Materials and Methods. Six dogs were included in this study. The mandibular premolars were extracted. For each hemimandible, three premolar extraction sites were randomly assigned to one of the following treatments: a covering collagen membrane, CPC with a covering collagen membrane, and a socket left empty. Cone-beam computed tomography (CBCT) measurements, polyfluorochrome sequential labeling, and histological assessments were performed to investigate the healing ability and repair processes within a 6-month observation period. Results. Buccal bone height in the membrane group was significantly higher than that in the membrane+CPC and blank groups at 4 and 6 months after extraction. The mineral apposition rate over 2-4 months and the alizarin red-stained area in the membrane group were significantly higher than those in the other two groups. Histological analysis after 6 months of healing showed significantly higher amounts of newly formed bone in the membrane group than in the other groups. Conclusion. Extraction sites treated with collagen barrier membranes showed better protection than sites not covered with membranes. And the buccal bone wall of the socket was well preserved by collagen membrane without extra CPC materials. Socket preservation using absorbable membranes alone yielded better quality and quantity of regenerated bone inside the socket site.
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Willison, J. H. M., M. I. N. Zhang e L. V. Gusta. "A freeze-fracture study of the influence of frost hardening treatments on the plasma membranes of Medicago sativa and Bromus inermis cell suspension cultures". Canadian Journal of Botany 68, n.º 5 (1 de maio de 1990): 949–54. http://dx.doi.org/10.1139/b90-121.
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Freeze-fractured suspension cultured cells of alfalfa (Medicago sativa L.) and bromegrass (Bromus inermis Leyss) were examined before and after frost hardening treatments for evidence of plasma membrane adaptation to frost. No chemical fixatives or cryoprotective agents were used and care was taken to ensure that there was no subjective bias in making counts of intramembrane particles. There were no patches of membrane free of intramembrane particles in any of the treatments, and only small differences in intramembrane particles frequencies were found. Cold hardening and abscisic acid hardening may have had different effects on intramembrane particles frequency, but because of the low level of statistical significance this was uncertain. Two arrays of membrane particles (strings and rosettes) were present in all treatments. It is concluded that the technique may be insufficiently sensitive to detect the subtle changes in membrane protein composition that probably accompany adaptation to frost. Key words: Medicago sativa, Bromus inermis, frost hardiness, membrane structure, freeze-fracture.
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Charcosset, Catherine. "Classical and Recent Developments of Membrane Processes for Desalination and Natural Water Treatment". Membranes 12, n.º 3 (25 de fevereiro de 2022): 267. http://dx.doi.org/10.3390/membranes12030267.
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Water supply and water treatment are of major concern all around the world. In this respect, membrane processes are increasingly used and reported for a large range of applications. Desalination processes by membranes are well-established technologies with many desalination plants implemented in coastal areas. Natural water treatment is also well implemented to provide purified water for growing population. This review covers various aspects of desalination: membranes and modules, plants, fouling (scaling, biofouling, algal blooms), cleaning, pretreatment (conventional and membrane treatments), energy and environmental issues, renewable energies, boron removal and brine disposal. Treatment of natural water focuses on removal of natural organic matter, arsenic, iron, nitrate, fluoride, pesticides and herbicides, pharmaceutical and personal care products. This review underlines that desalination and natural water treatment require identical knowledge of membrane fouling, construction of large plants, cleaning procedures, energy and environmental issues, and that these two different fields can learn from each other.
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Gross, Andreas, Arthur Morvezen, Pedro Castillo Gomez, Xuesong Xu e Pei Xu. "Numerical Investigation of the Effect of Two-Dimensional Surface Waviness on the Current Density of Ion-Selective Membranes for Electrodialysis". Water 11, n.º 7 (7 de julho de 2019): 1397. http://dx.doi.org/10.3390/w11071397.
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Ion-selective membranes are an important component of electrodialysis stacks for desalination. Manufacturing imperfections or slight inhomogeneity of the material can lead to minute membrane surface imperfections. Two-dimensional solutions of the coupled Poisson–Nernst–Planck and Navier–Stokes equations were sought for a perfectly smooth membrane and for membranes with well-defined small-amplitude harmonic surface roughness. The simulations were carried out with the validated rheoEFoam solver by Pimenta and Alves. In the overlimiting regime, the electric field is strong enough for an electrokinetic instability to occur. The instability leads to disturbance growth and the formation of electro-convection cells, which strongly increase the current density. The present simulations show that with an increasing ion concentration and applied voltage, the instability becomes stronger and the overlimiting regime is reached earlier. The limiting current density shows a noticeable dependence on the wavelength of the surface roughness. When the wavelength of the surface roughness is incommensurate with the wavelength of the naturally occurring instability, the limiting current density is increased. Since production membranes will always have some degree of surface roughness, this suggests that membrane surface treatments which favor certain wavelengths may have an effect on the overall membrane performance.
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Mehanathan, Shaymala, Juhana Jaafar, Atikah Mohd Nasir, Roshanida A. Rahman, Ahmad Fauzi Ismail, Rosli Md Illias, Mohd Hafiz Dzarfan Othman, Mukhlis A Rahman, Muhammad Roil Bilad e Muhammad Nihal Naseer. "Adsorptive Membrane for Boron Removal: Challenges and Future Prospects". Membranes 12, n.º 8 (18 de agosto de 2022): 798. http://dx.doi.org/10.3390/membranes12080798.
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The complexity of removing boron compounds from aqueous systems has received serious attention among researchers and inventors in the water treating industry. This is due to the higher level of boron in the aquatic ecosystem, which is caused by the geochemical background and anthropogenic factors. The gradual increase in the distribution of boron for years can become extremely toxic to humans, terrestrial organisms and aquatic organisms. Numerous methods of removing boron that have been executed so far can be classified under batch adsorption, membrane-based processes and hybrid techniques. Conventional water treatments such as coagulation, sedimentation and filtration do not significantly remove boron, and special methods would have to be installed in order to remove boron from water resources. The blockage of membrane pores by pollutants in the available membrane technologies not only decreases their performance but can make the membranes prone to fouling. Therefore, the surface-modifying flexibility in adsorptive membranes can serve as an advantage to remove boron from water resources efficiently. These membranes are attractive because of the dual advantage of adsorption/filtration mechanisms. Hence, this review is devoted to discussing the capabilities of an adsorptive membrane in removing boron. This study will mainly highlight the issues of commercially available adsorptive membranes and the drawbacks of adsorbents incorporated in single-layered adsorptive membranes. The idea of layering adsorbents to form a highly adsorptive dual-layered membrane for boron removal will be proposed. The future prospects of boron removal in terms of the progress and utilization of adsorptive membranes along with recommendations for improving the techniques will also be discussed further.
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Djoko Kusworo, Tutuk, Annizah Rahmatya Gerhana e Noor Hanifah Angga Putra. "Enhancement Performance of Hybrid Membrane Zeolite/PES for Produced Water Treatment With Membrane Modification Using Combination of Ulta Violet Irradiation, Composition of Zeolite and Thermal Annealing". MATEC Web of Conferences 156 (2018): 08002. http://dx.doi.org/10.1051/matecconf/201815608002.
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Produced water is a wastewater from oil production that must be treated well. Membrane is one alternative of water treatments technology based on filtration method. However, in the use of membrane, there’s no exact optimal variable that influences membrane performance.This underlying research to assess factors that influences membrane performance to obtain optimal condition. Therefore, the objectives of this study are determining the effect of variable process in membrane fabrication and several modification techniques on membrane performance. The membranes were fabricated via dry-wet phase inversion method. The process variables of this experiment are varying the Zeolite concentration by low level 1% weight and 3% weight, UV irradiation time low level 2 minutes and high level 6 minutes, thermal annealing temperature low level 160°C and high level 180°C. The experiment runs were designed using central composite design. From the research that has been perfromed, PES/Zeolit membrane has a higher permeability after being irradiated by UV light and denser pore after heating and the longer of annealing time.
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Sebokova, E., M. L. Garg e M. T. Clandinin. "Modulation of receptor-mediated gonadotropin action in rat testes by dietary fat". American Journal of Physiology-Endocrinology and Metabolism 254, n.º 6 (1 de junho de 1988): E708—E712. http://dx.doi.org/10.1152/ajpendo.1988.254.6.e708.
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The effect of feeding diets enriched with 18:2 omega 6, 18:3 omega 3, or saturated fatty acids on lipid composition and receptor-mediated action of luteinizing hormone/human chorionic gonadotropin (LH/hCG) in rat testicular plasma membranes was investigated. Linoleic and alpha-linolenic acid treatments reduced total phospholipid and cholesterol content of the testicular plasma membrane and altered membrane phospholipid composition. Change in phospholipid and cholesterol content after feeding the polyunsaturated fats decreased cholesterol to phospholipid ratios and binding capacity of the LH/hCG receptor in the testicular plasma membrane. LH-stimulated adenylate cyclase activity was decreased in animals fed the linolenic acid-rich diet. NaF-stimulated adenylate cyclase activity was decreased in animals fed diets high in either polyunsaturated fatty acid. Decreased plasma membrane LH/hCG receptor content was associated with decreased testosterone production in Leydig cells in response to LH in the linolenic acid-fed group. It is suggested that change in cholesterol-to-phospholipid ratios alters the physical properties of testicular plasma membranes in a manner that influences accessibility of LH/hCG receptors in testicular tissue.
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Sackstein, Robert, e Charles J. Dimitroff. "A hematopoietic cell L-selectin ligand that is distinct from PSGL-1 and displays N-glycan–dependent binding activity". Blood 96, n.º 8 (15 de outubro de 2000): 2765–74. http://dx.doi.org/10.1182/blood.v96.8.2765.
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Abstract Human hematopoietic progenitor cells express L-selectin and also express PSGL-1, a ligand for all selectins. Using a shear-based adhesion assay, a hematopoietic cell L-selectin ligand (HCLL) that is expressed on the hematopoietic cell line KG1a and on normal human hematopoietic progenitors was previously identified. To characterize the structural biology of HCLL and to define its relationship to PSGL-1, the effects of chemical and enzymatic treatments on HCLL activity of KG1a cells and membrane preparations were analyzed. Protease digestions and chemical treatments of KG1a cells and membranes indicated that HCLL is an integral membrane glycoprotein. Glycosidase digestions of membrane protein preparations and metabolic treatments of KG1a cells with glycosylation processing modifiers revealed that L-selectin binding determinants on HCLL are sialofucosylated structures presented on complex-type N-glycans. Adhesion assays and biochemical studies showed that this glycoprotein is also expressed on circulating blasts in native acute leukemias. HCLL is distinguishable from PSGL-1: (1) KG1a cells sorted for PSGL-1 expression had equivalent HCLL activity; (2) anti–PSGL-1 blocking antibodies and proteases known to eliminate L-selectin binding to PSGL-1 had no effect on HCLL binding activity of KG1a cells; (3) blasts from native leukemias with low expression of PSGL-1 and CD34 display high HCLL activity; and (4) despite high level expression of PSGL-1, HCLL activity was absent on HL60 cells. These data provide first evidence of a naturally expressed membrane L-selectin ligand expressing binding determinant(s) on an N-linked glycoconjugate. This novel ligand may help mediate L-selectin–dependent cell-cell adhesive interactions within the cytoarchitecture of the bone marrow microenvironment.
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Sackstein, Robert, e Charles J. Dimitroff. "A hematopoietic cell L-selectin ligand that is distinct from PSGL-1 and displays N-glycan–dependent binding activity". Blood 96, n.º 8 (15 de outubro de 2000): 2765–74. http://dx.doi.org/10.1182/blood.v96.8.2765.h8002765_2765_2774.
Texto completo da fonteResumo:
Human hematopoietic progenitor cells express L-selectin and also express PSGL-1, a ligand for all selectins. Using a shear-based adhesion assay, a hematopoietic cell L-selectin ligand (HCLL) that is expressed on the hematopoietic cell line KG1a and on normal human hematopoietic progenitors was previously identified. To characterize the structural biology of HCLL and to define its relationship to PSGL-1, the effects of chemical and enzymatic treatments on HCLL activity of KG1a cells and membrane preparations were analyzed. Protease digestions and chemical treatments of KG1a cells and membranes indicated that HCLL is an integral membrane glycoprotein. Glycosidase digestions of membrane protein preparations and metabolic treatments of KG1a cells with glycosylation processing modifiers revealed that L-selectin binding determinants on HCLL are sialofucosylated structures presented on complex-type N-glycans. Adhesion assays and biochemical studies showed that this glycoprotein is also expressed on circulating blasts in native acute leukemias. HCLL is distinguishable from PSGL-1: (1) KG1a cells sorted for PSGL-1 expression had equivalent HCLL activity; (2) anti–PSGL-1 blocking antibodies and proteases known to eliminate L-selectin binding to PSGL-1 had no effect on HCLL binding activity of KG1a cells; (3) blasts from native leukemias with low expression of PSGL-1 and CD34 display high HCLL activity; and (4) despite high level expression of PSGL-1, HCLL activity was absent on HL60 cells. These data provide first evidence of a naturally expressed membrane L-selectin ligand expressing binding determinant(s) on an N-linked glycoconjugate. This novel ligand may help mediate L-selectin–dependent cell-cell adhesive interactions within the cytoarchitecture of the bone marrow microenvironment.
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Kavafaki, Sofia, George Bomis, Kyriaki Drakaki, Athanasios Varoutoglou, Konstantinos Kiourtzidis, George Z. Kyzas e Athanasios C. Mitropoulos. "Investigation of Duplex Brass Membranes with Metallography, Permeability and Treatments: Work-Hardening, Annealing and Quenching". ChemEngineering 5, n.º 4 (3 de novembro de 2021): 76. http://dx.doi.org/10.3390/chemengineering5040076.
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This paper consists of the fabrication and investigation of metal membranes and the study of their behaviour and applications in gas separation processes. The scope is to produce and characterize the porous crystal structure of brass alloy (standardization: DIN 17660) membranes and measure their permeability with helium as a penetrant medium. Another part of this study is to alter the brass alloy’s structure throughout metallurgical treatments and investigate how the permeability is allied to the structure’s alteration. This work merges the knowledge and technology of inorganic porous materials science in metallurgy. The novelty of the current research resides in the process to alternate the brass alloy structure throughout metallurgical treatments and how it is allied to the permeability of the membrane, which is of interest to be investigated. The results of the research are analysed and compared conducting the final inferences. All metallurgical treatments resulted in low permeability values when compared to a non-treated specimen. Specifically, the drop in permeance ranged from 76 up to 99.56%. It is noted that consecutive treatments contributed to even further decreases.