Letteratura scientifica selezionata sul tema "Membrane treatments"
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Articoli di riviste sul tema "Membrane treatments"
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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. 22 (20 novembre 2020): 5254. http://dx.doi.org/10.3390/ma13225254.
Testo completoAbstract (sommario):
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.
2
Malczewska, Beata, Paweł Lochyński, Sylwia Charazińska, Andrzej Sikora e Ramin Farnood. "Electrospun Silica-Polyacrylonitrile Nanohybrids for Water Treatments". Membranes 13, n. 1 (6 gennaio 2023): 72. http://dx.doi.org/10.3390/membranes13010072.
Testo completoAbstract (sommario):
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. 22 (15 novembre 2022): 3644. http://dx.doi.org/10.3390/foods11223644.
Testo completoAbstract (sommario):
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. 2 (23 gennaio 2023): 147. http://dx.doi.org/10.3390/membranes13020147.
Testo completoAbstract (sommario):
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. 8 (22 agosto 2022): 816. http://dx.doi.org/10.3390/membranes12080816.
Testo completoAbstract (sommario):
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. 1 (2012): 2–9. http://dx.doi.org/10.5360/membrane.37.2.
Testo completo
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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. 12 (9 dicembre 2021): 969. http://dx.doi.org/10.3390/membranes11120969.
Testo completoAbstract (sommario):
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. 1 (15 gennaio 2018): 104–9. http://dx.doi.org/10.1017/s0967199417000727.
Testo completoAbstract (sommario):
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. 13 (20 maggio 2011): 4657–68. http://dx.doi.org/10.1128/aem.00323-11.
Testo completoAbstract (sommario):
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. 3 (marzo 1997): 533–45. http://dx.doi.org/10.1091/mbc.8.3.533.
Testo completoAbstract (sommario):
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.
Tesi sul tema "Membrane treatments"
1
Pinos, Vélez Verónica Patricia. "Development and optimization of catalytic membrane reactors for wastewater treatments". Doctoral thesis, Universitat Rovira i Virgili, 2016. http://hdl.handle.net/10803/365578.
Testo completoAbstract (sommario):
Es van obtenir diferents reactors catalítics de membrana (RCM) de membrana de fibra buida de Corindó i nanopartícules de Pd obtingudes per diferents metodologies: humitat incipients impregnació, polvorització catòdica, microemulsió i aliatge amb coure pel mètode de Poliol. RCMs es van provar en medi aquós, pressió ambiental i temperatura o 60 c en generació in situ de peròxid d'hidrogen, l'oxidació i hidrogenació de fenol i ibuprofè i reducció de Cr (VI). La RCM ha actuat com interfície catalítica per tal d'activar l'hidrogen i que reaccione amb oxigen o compost orgànic o inorgànic. La RCM impregnada amb Pd és l'única que van mostrar activitat i tests d'estabilitat. Aquest comportament es va deure a la presència d'àtoms i grups de Pd. La manca activitat de la resta de catalitzadors amb Pd es va deure a la formació d'hidrur de Pd en les condicions de reacció.Se obtuvieron diferentes reactores catalíticos de membrana (RCM) desde membranas de fibra hueca de corindón y nanopartículas de paladio obtenidas por diferentes métodos: Impregnación a humedad incipiente, sputtering, microemulsion y aleación con cobre por el método del poliol. Los RCM fueron probados en medio acuoso, presión ambiental y temperatura ambiente o 60C en la generación in situ de peróxido de hidrógeno, oxidación e hidrogenación de fenol e ibuprofeno y reducción de Cr(VI). Los RCM actuaron como interfaz catalítica para que el hidrógeno se active y reaccione con el oxígeno o el compuesto orgánico o inorgánico. Los RCM con paladio por impregnación fueron los únicos que presentaron actividad y estabilidad en las pruebas. Este comportamiento se dio gracias a la presencia de átomos y clusters de paladio. La falta de actividad de los otros catalizadores de paladio se debió a la formación de hidruro de paladio en las condiciones de reacción.
Different catalytic membrane reactors (CMRs) were obtained from hollow fiber membranes corundum and palladium nanoparticles obtained by different methods: Incipient wetness impregnation , sputtering , microemulsion and copper alloy by the method of the polyol. The CMRs were tested in aqueous medium, ambient pressure and ambient temperature or 60C for the in situ generation of hydrogen peroxide, oxidation and hydrogenation of phenol and ibuprofen and reduction of Cr(VI). The catalytic CMR acted as interface for the reactions between hydrogen with oxygen or organic or inorganic compound. Only the CMRs with palladium by impregnation were actives and stabilites during the tests. This behavior occurred thanks to the presence of clusters and single atoms of palladium. The lack of activity of the other kind of palladium catalysts were due to the formation of palladium hydride in the reaction conditions.
2
Wu, Hong. "Sulfate radical based ceramic catalytic membranes for water treatments". Thesis, Edith Cowan University, Research Online, Perth, Western Australia, 2020. https://ro.ecu.edu.au/theses/2382.
Testo completoAbstract (sommario):
The discharge of antibiotics into natural aquatic environment without proper treatments results in the propagation of antibiotics-resistant strains. Effective remediation technologies are therefore urged to remove those emerging contaminants from water. However, antibiotics are difficult to be degraded through a traditional biological treatment because they would deactivate the effective bacteria used in the process. Advanced oxidation processes (AOPs) using highly reactive oxygen species (ROS) such as hydroxyl radicals ( OH) and sulfate radicals (SO4 •− • ) have been widely employed as an efficient way for antibiotics degradation owing to the high oxidation ability, non-selectivity and low cost. However, the recovery of the suspended catalysts after use is the biggest obstacle for the wide application. Meantime, membrane separation has also been extensively applied as a promising wastewater treatment technology with the advantages of long-term operation, low energy consumption and high yield of production. The membrane fouling is, however, a critical issue restricting the widespread application of membrane. For addressing above-mentioned issues, with extensive technological and scientific endeavours, this PhD study focused on the development of novel integration technology of AOPs and membrane separation for antibiotics degradation. In this research, heterogeneous AOPs processes coupled with independent membrane separation unit for suspended catalysts recovery were studied. Moreover, metal oxide based-catalytic membrane for concurrent AOPs and membrane separation were investigated. Firstly, boron, nitrogen co-doped carbon nanotubes supported FeOOH (FeOOH@BNC) was synthesized for the degradation of sulfamethoxazole (SMX) by Fenton-like reaction. The as-synthesized FeOOH@BNC showed an excellent performance in SMX removal (Chapter 3). Secondly, boron, nitrogen co-doped nanotubes (BNC) were developed. The BNC nanotubes with a high specific area, abundant active sites, and controllable N–B–C structures demonstrated prominent peroxymonosulfate (PMS) activation ability towards 4-hydroxylbenzoic acid (HBA) degradation (Chapter 4). It was also found that both FeOOH@BNC and BNC suspended catalysts in the treated solution can be well recovered via membrane filtration (Chapter 3 and 4). Finally, two metal oxide-based catalytic ceramic membranes (Co3O4@CM and MnO2@CM) were prepared via a simple one-step ball-milling method with a high temperature sintering. The as-prepared Co3O4@CM and MnO2@CM composite catalytic membranes were characterized and tested for the degradation of aqueous HBA solution by SR-AOPs procedure. It was found that the composite membranes showed excellent HBA removal efficiencies, good reusability and high anti-fouling performances (Chapter 5 and 6). Mechanistic studies, e.g. materials chemistry, generation of reactive radicals, and degradation pathways, were also carried out. The developed catalysts, catalyst membranes, and the combined processes as well as the mechanistic studies are expected to provide significant contributions in terms of both technology and scientific knowledge to remediation of emerging contaminants.
3
Gandi, Ravikishor. "Treatments of hemi caustic and extractives streams". Thesis, Georgia Institute of Technology, 2012. http://hdl.handle.net/1853/44781.
Testo completoAbstract (sommario):
Disposal of effluent from pulp and paper industry is one of the major problems faced by entrepreneur in view of increasing environmental standards day by day. In addition to this, industry loses economic value by disposing the effluent or selling it for a low price to other industries. Therefore, to address this problem, in the present study, 2 pulp mill effluents were selected to recover the economic value namely Hemi caustic stream and brown stock filtrate.
As far as the recovery of value of hemi caustic stream is concerned, freeze concentration technique was used to recover water in its pure form and membrane separation was used to separate hemi cellulose from effluent so that permeate can be used as a pure source of caustic elsewhere. In addition to this, hemi caustic stream was subjected to acid hydrolysis to convert hemi cellulose into sugars. These sugars can be used to produce bioethanol.
As far as the recovery of values of brown stock filtrate is concerned, it was proposed to recycle brown stock filtrate as a source of washing water for brown stock washers in the mill. However, continuous recycling of brown stock filtrate into the process causes building up of extractives in the recycle stream which in turn might deposit on the pulp and affects the quality of the pulp. Therefore, it was decided to separate extractives from the brown stock filtrate before recycle it into the mill. Dissolved Air flotation technique was used to achieve the above mentioned objective. An attempt was made to develop an improved and most reliable version of existing extractives measurement method to quantify the performance of Dissolved air flotation technique.
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Yu, Feiran. "Physicochemical Modifications of Milk Fat Globule Membrane Proteins During Temperature Processing of Milk". The Ohio State University, 2018. http://rave.ohiolink.edu/etdc/view?acc_num=osu1534770720065921.
Testo completo
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Francis, A. "The effects of ageing and low temperature pre-sowing treatments on the membrane status and germination performance of tomato seeds". Thesis, University of Bedfordshire, 1985. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.304311.
Testo completo
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Maxwell, Deborah. "REMEDIATION OF HEAVY METAL CONTAMINATION IN SEDIMENTS: APPLICATION OF IN SITU TREATMENT UTILIZING EMULSIFIED LIQUID MEMBRANE AN". Master's thesis, University of Central Florida, 2007. http://digital.library.ucf.edu/cdm/ref/collection/ETD/id/4329.
Testo completoAbstract (sommario):
Heavy metal contamination of soils, sediments and groundwater presents an ongoing source of hazardous and persistent environmental pollution. How best to remediate these contaminants is the impetus of continuing research efforts. Methods include containment, ex situ and in situ techniques. A successful in situ method utilizing a combination of emulsified liquid membranes, ELM, and zero-valent metal, ZVM, and bimetals has demonstrated impressive heavy metal reduction in 100 ppm solutions of Cd, Cu, Ni, Pb, Cr and U. This promising in situ method has been employed by the Industrial Chemistry Laboratory at the University of Central Florida and it has demonstrated considerable success in treating several environmental threats. Contaminated soils, surfaces, sediments and groundwater with offending agents such as trichloroethene, polychorobiphenyls and heavy metals have been treated utilizing emulsified liquid membrane systems containing zero-valent iron or bimetal particles. In vial studies, lead spiked sediments have shown repeatable 60% removal of lead after seven days of treatment. A persistent pattern emerged at ten days whereupon remediation levels began to drop. The current study was established to determine the reason for the decline at ten days and beyond. Questions addressed: Does the formation of an impeding oxide layer diminish the remediation capacity of the iron/magnesium system? Does the emulsion reach a maximum capacity to withdraw the contaminant? Do the soil components or the soil structure interfere with the access to the contaminant? This study has yielded insight into the reasons emulsified liquid membrane systems containing zero-valent metals achieved maximum lead removal at day seven, and thereafter begin to lose their effectiveness. A three part study was implemented to address and to answer the three questions pertaining to the consistent pattern of diminishing remediation levels exhibited at day ten and beyond. Initially, from Study I results it appeared that the formation of an impeding oxide layer on the bi-metal which was inside the emulsion droplet and which plated or precipitated with the lead was not occurring at day ten. Results indicated that the iron/magnesium was still capable of removing lead. Furthermore, from Study II results the emulsion dose injected appeared adequate to remove the lead, meaning that the emulsion had not reached its maximum capacity for remediation. The emulsion dose was not a limiting factor. Lastly, Study III results seemed to indicate that the drop in remediation after day seven pertained to the soil structure. There appeared to be some merit to the idea that with aging of the sediment, the lead was diffusing and migrating to some inaccessible interior sites within the sediment particles. Additionally, indications from day ten and day fourteen delineated that a second emulsion dose injection might restore lead removal levels to approach those first observed at day seven and consequently be a useful field application. In order to explore the effectiveness of injecting a second dose of emulsion, another vial study was implemented. The typical pattern of observing sixty percent maximum lead removal at day seven was observed. In separate groups, a second injection of emulsion was added at day five, and then for another vial series, a second dose was added at day seven. The second emulsion dose treatment for either day five or day seven did not yield any increases in percent lead removal. Another theory emerged after viewing micrographs of recovered iron/magnesium compared with fresh ball-milled bimetal. In addition, scanning electron microscopy appeared to confirm the explanation that the emulsified zero-valent metal system might be compromised after day seven. This would lead to exposure of the iron/magnesium to the air and the elements. Corrosion of the bimetal might be occurring. With time, release of the plated or precipitated lead back into the sediment mixture could follow. The results of Study I had led to the conclusion that an impeding oxide layer had not formed; however, this conclusion may have been premature because the recovered iron/magnesium was exposed to lead solution in the vial study. Perhaps if the recovered iron/magnesium was inserted back into an emulsion and injected into lead spiked sediments the percent lead removed might give a more accurate picture of the iron/magnesium's capability to continue performing remediation. Remediation of sediments contaminated with lead is a complicated task because of the complex nature of sediment components. Emulsified liquid membranes utilizing zero-valent bimetals has repeatedly demonstrated impressive results at day seven; however, this treatment method is not without its limitations. Optimal results appear to be gained at day seven after emulsion injection. The bimetal and plated or precipitated lead must be removed at that point; otherwise the effective remediation of the contaminant is progressively reversed.M.S.
Department of Chemistry
Sciences
Industrial Chemistry MS
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Osborn, Shawn James. "Morphological and Mechanical Properties of Dispersion-Cast and Extruded Nafion Membranes Subjected to Thermal and Chemical Treatments". Diss., Virginia Tech, 2009. http://hdl.handle.net/10919/37517.
Testo completoAbstract (sommario):
The focus of this research project was to investigate morphological and mechanical properties of both extruded and dispersion-cast Nafion® membranes. The project can be divided into three primary objectives; obtaining a fundamental understanding of the glass transition temperature of Nafion®, determining the effect of thermal annealing treatments on the morphology and mechanical properties of dispersion-cast Nafion®, and examination of dispersion-cast Nafion® subjected to an ex-situ, Fentonâ s chemical degradation test. Nafion®, a perfluorosulfonate ionomer, is considered a commercially successful semi-crystalline ionomer with primary applications in chlor-alkali cells and proton exchange membrane fuel cells.
With the aid of dynamic mechanical analysis (DMA) and dielectric spectroscopy (DS), we were able to provide definitive evidence for a genuine glass transition in Nafion®. DMA of Nafion® samples that were partially neutralized with tetrabutylammonium counterions showed a strong compositional dependence suggesting that the β-relaxations of H+-form Nafion® and the neutralized ionomers have the same molecular origin with respect to backbone segmental motions. Building upon our previous studies of the molecular and morphological origins of the dynamic mechanical relaxations of Nafion® neutralized with a series of organic ions, the glass transition temperature of H+-form Nafion® is now confirmed to be the weak β-relaxation centered at -20 °C. Dielectric spectra also showed this transition from the perspective of dipole relaxation. The signature of cooperative long range segmental motions in dielectric spectra was seen here, as with other polymers, mainly through the excellent agreement of the β-relaxation time-temperature dependence with the Vogel-Fulcher-Tammann equation.
We have also discovered that new dispersion-cast H+ form Nafion® membranes are susceptible to disintegration/dissolution when subjected to boiling methanol. In this work, we have achieved significant decreases in the percent solubility of H+-form Nafion® by either thermally annealing above 175 °C or solution-processing at 180 °C using a high boiling point solvent. Small Angle X ray Scattering (SAXS) displayed a change in the morphology of H+ form membranes with increasing annealing temperature by a shift in the crystalline scattering peak (q â 0.05 à 1) to lower q values. Counterion exchange of Nafion® from H+ to Na+ form had no influence on the membraneâ s susceptibility to disintegration in boiling methanol. In order to achieve mechanical stability in boiling methanol, Na+ form membranes had to be annealed at 275 °C for at least fifteen minutes. The SAXS data of annealed Na+ form membranes showed a dramatic decrease in crystalline order with annealing temperature, ultimately leading to the disappearance of the crystalline scattering peak after fifteen minutes at 275 °C. The onset of methanol stability with the melting of Nafion® crystallites suggests that chain entanglement is an important parameter in obtaining solvent stability.
With respect to chemical stability, we performed studies aimed at examining the effects of Fentonâ s Reagent on the resistance to radical attack of new generation, dispersion-cast Nafion®. Changes in the 19F solid-state NMR spectra of dispersion-cast Nafion® before and after chemical degradation via Fentonâ s Reagent predicts a rather random attack by â ¢OH and â ¢OOH radicals. Several membranes were also thermally annealed between 100-250 °C in an attempt to correlate crystallinity with chemical degradation kinetics of Nafion® via Fentonâ s Reagent. The results indicate that the effect of counterion exchange into the Na+ form was minimal, but the degree of thermal degradation had a tremendous effect on the fluoride release rate and chemical degradation kinetics. By exchanging the membranes into the Na+ form, thermal degradation was avoided, allowing us to study the role of crystallinity as a function of fluoride release. Ultimately, Nafion® crystallinity was deemed an important factor in deterring peroxide radical attack. As the percent crystallinity decreased with annealing temperature, the fluoride concentration in the resulting Fentonâ s media increased accordingly, indicating that the amorphous regions of the polymer are more susceptible to chemical degradation via peroxide radical attack.Ph. D.
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MANIGAS, LUISA. "Use of membrane bioreactors for the bioremediation of groundwater polluted by chlorinated compounds". Doctoral thesis, Università degli Studi di Cagliari, 2008. http://hdl.handle.net/11584/265895.
Testo completoAbstract (sommario):
The aim of this experimental work has been the application of a new polluted waters treatment technology for the selection of a bacterial population capable of bioremediating a synthetic groundwater polluted by four different chlorinated compounds. The innovative technology applied in this study was the biological treatment system known as MSBR (Membrane Sequencing Bioreactor), which consists of a Sequencing Batch Reactor (SBR) coupled to a membrane module for the filtration of the biological sludge that degrades the chlorinated compounds present in the polluted water fed to the system. The synthetic groundwater used in this experimentation contained four chlorinated compounds: 1,2-dichloroethane, 1,2-dichlorobenzene, 2-chlorophenol and trichloroethylene. During the development of the research, the chlorinated compounds were fed either alone on in different mixtures in order to identify possible effects of each substrate on the degradability of the others. Some operational parameters were varied in order to check the possibility of implementing the system at a larger scale. The MSBR system equipped in this study was effective in the acclimation of a sludge to hardly biodegradable xenobiotic compounds, and the degradation rates achieved were comparable to other similar studies performed, even if in this experimentation, differing from all the others found in literature, good removal rates were achieved for the degradation of the substrates when they were fed in mixtures.
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Wagh, Priyesh Ashokrao. "SYNTHESIS OF BIOLOGICALLY-INSPIRED NANOFILTRATION MEMBRANES USING PROTECTED, MUTATED, AND SIMULATED AQUAPORINS". UKnowledge, 2018. https://uknowledge.uky.edu/cme_etds/92.
Testo completoAbstract (sommario):
Gram-negative bacterial cells are surrounded by a cell membrane which protects the cell and controls the transport of nutrients and waste products in and out of the cells at a fast rate. This rapid transport of nutrients and wastes through the cell membrane is made possible by channel proteins called porins. Various types of porins present in the cell membrane have specific functions depending on their selectivity towards different nutrients, and channel proteins selective towards water are called aquaporins. These proteins restrict the passage of all entities except water molecules and they provide a fast transport rate of water molecules at 109 molecules/second per channel.
The high selectivity of porins has led to their incorporation into synthetic systems, and one example is the addition of porins to separations membranes in order to enhance their performance in terms of selectivity and permeability, in a field called biomimetics. The concept of incorporating aquaporins into synthetic membranes has been studied for the last 10 years in order to enhance the water permeability and selectivity of membranes for water purification; however, there are still limitations such as high costs, difficulties in fabrication of aquaporins, their alignment into synthetic membrane assembly, low stability, and limitations on number of aquaporin molecules that can be introduced into synthetic membranes limit their applicability.
In recent years, concurrent with the work on aquaporin-based biomimetic membranes, there has been an increase in the study of synthesizing molecules with similar structure-function relationships of aquaporins. These artificial channels attempt to mimic the high-water permeability and selectivity of aquaporins, while being synthesized using simple chemistry, being solvent compatible, and requiring less space on the membrane surface which helps to incorporate more channels into the membrane assembly.
The objectives of this study were to first incorporate aquaporins into synthetic nanofiltration membranes without chemical alteration them to prevent flattening or denaturing of aquaporins; then, the second objective was to install functional groups on aquaporins and align them in the direction of water flow; lastly, the third objective was to synthesize artificial channels in order to overcome the issues with aquaporin stability, alignment, and efficient packing of water channels onto the membrane surface.
For the first objective, aquaporins were treated with a polysaccharide, gum Arabic, and incorporated into an amphiphilic polymer, polyvinyl alcohol with alkyl side chains (PVA-alkyl), in order to simulate the natural housing of lipid bilayer for aquaporins and to protect them from denaturing. Long alkyl chains provided the hydrophobic component, while PVA provided the hydrophilic component of the amphiphilic polymer. Membranes modified with aquaporins displayed lower flux declines and higher flux recoveries after reverse flow filtration, along with improved rejection values for both protein and salt solutions as compared to PBI and PBI-PVA-alkyl membranes. However, there was leakage of ions between channels.
Therefore, in order to improve the rejection of protons, ions and other impurities, the channels were aligned with the direction of water flow. Functional groups were installed on Aquaporins using site-directed mutagenesis for covalent attachment to the polymer matrix so that the proteins could be immobilized to the membranes and aligned in the direction of the flow. Aquaporin constructs were modified to bear affinity tags or unique amino acids at the N-terminus of the aquaporin molecule, which was used to facilitate directional immobilization. Each aquaporin monomer was modified with a unique amino acid Cys group at the N-terminus right after the first Met, and due to the aquaporin tetrameric nature, these Cys groups became four anchors for attachment. The presence of these four Cys anchors per aquaporin tetramer was used to attach on the membrane surface in alignment with the feed water flow direction. Membranes modified with mutated aquaporins showed consistently higher salt rejection values of ~70% irrespective of feed concentration, along with higher flux recoveries and lower flux declines. Commercial NF-270 membranes provide a monovalent salt (NaCl) rejection of ~50% and divalent salt (MgCl2) rejection of 97%. Also, approximate coverage of membrane surface with attached aquaporins was calculated using simulation studies. Simulation studies showed that immobilized aquaporins with PVA-alkyl provided a diffusion rate equivalent to 64% coverage on the membrane surface. This showed that aquaporins didn’t cover the entire surface area of the membrane. However, immobilized aquaporins were responsible for the rejection of a portion of ions passing through the membrane.
In order to overcome the limitations of aquaporin incorporation into polymer membranes, artificial organic frameworks were added as surface modification on PBI membranes. Organic frameworks were synthesized as derivatives of hybrid bisamides. The series of bisamides 1-4 consist of 6-amino-pyridine-2-dicarboxylic acid, 6-hydroxymethyl-pyridine-2-carboxylic acid and ethylenediamine, trimethylenediamine, putrescine, and cadaverine depending on the length of carbon chain. These frameworks are amphiphilic in nature and have strong chemical attachment due to the presence of amines and carboxylic acids into each building block. These molecules were introduced into the membrane matrix using carbodiimide chemistry. FTIR results showed the attachment of these bisamide molecules onto the surface of a modified PBI membrane. Also, modified membranes showed a reduced molecular weight cut off (MWCO) for neutral organic molecules.
Overall, membranes modified with aquaporins have shown a potential to provide consistently high salt rejections with increasing feed solutions. Also, preliminary results have shown that bisamide molecules can be attached onto the membrane surface as organic frameworks and have a potential to be an alternative for aquaporins based biomimetic membranes.
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Timoteo, J?nior Jos? Fl?vio. "Membrana de alumina an?dica: comportamento da microestrutura e estudo das propriedades ?pticas ap?s tratamento t?rmico". Universidade Federal do Rio Grande do Norte, 2012. http://repositorio.ufrn.br:8080/jspui/handle/123456789/12798.
Testo completoAbstract (sommario):
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Thin commercial aluminum electrolytic and passed through reactions was obtained with anodic alumina membranes nanopores. These materials have applications in areas recognized electronic, biomedical, chemical and biological weapons, especially in obtaining nanostructures using these membranes as a substrate or template for processing nanowires, nanodots and nanofibers for applications noble. Previous studies showed that the membranes that have undergone heat treatment temperature to 1300? C underwent changes in morphology, crystal structure and optical properties. This aim, this thesis, a study of the heat treatment of porous anodic alumina membranes, in order to obtain and to characterize the behavior changes structures during the crystallization process of the membranes, at temperatures ranging between 300 and 1700? C. It was therefore necessary to mount a system formed by a tubular furnace resistive alumina tube and controlled environment, applying flux with special blend of Ag-87% and 13% N2, in which argon had the role of carrying out the oxygen nitrogen system and induce the closing of the pores during the densification of the membrane. The duration of heat treatment ranged from 60 to 15 minutes, at temperatures from 300 to 1700? C respectively. With the heat treatment occurred: a drastic reduction of porosity, grain growth and increased translucency of the membrane. For the characterization of the membranes were analyzed properties: Physical - thermogravimetric, X-ray diffraction, BET surface area; morphological - SEM, EDS through compositional and, optical absorbance, and transmittance in the UV-VIS, and FTIR. The results using the SEM showed that crystallization has occurred, densification and significant changes in membrane structure, as well as obtaining microtube, the BET analysis showed a decrease in specific surface area of the membranes has to 44.381 m2.g-1 to less than 1.8 m2.g-1 and in the analysis of transmittance and absorbance was found a value of 16.5% in the range of 800 nm, characteristic of the near infrared and FTIR have confirmed the molecular groups of the material. Thus, one can say that the membranes were mixed characteristics and properties which qualify for use in gas filtration system, as well as applications in the range of optical wavelength of the infra-red, and as a substrate of nanomaterials. This requires the continuation and deepening of additional study
L?minas delgadas de alum?nio comercial passaram por rea??es eletrol?ticas e obtiveram-se membranas de alumina an?dica com nanoporos. Estes materiais t?m reconhecidas aplica??es nas ?reas eletr?nicas, biom?dicas, qu?micas e biol?gicas, principalmente, na obten??o de nanoestruturas utilizando estas membranas como substrato ou molde para processamento de nanofios, nanopontos e nanofibras para aplica??es nobres. Estudos anteriores apontaram que as membranas que passaram por tratamentos t?rmicos at? a temperatura de 1300? C, sofreram altera??es na morfologia, na estrutura cristalina e nas propriedades ?pticas. O objetivo deste trabalho foi o estudo do tratamento t?rmico de membranas de alumina an?dica porosas, com o intuito de obter e caracterizar as altera??es de comportamento das estruturas, durante o processo de cristaliza??o das membranas, em temperaturas que variaram entre 300 e 1700? C. Assim, foi necess?rio montar um sistema formado por um forno resistivo tubular e tubo de alumina com ambiente controlado, aplicando fluxo com mistura especial de Ar-87% e N2-13%, no qual o arg?nio teve o papel de carrear o oxig?nio para fora do sistema e o nitrog?nio de induzir o fechamento dos poros, durante a densifica??o das membranas. A dura??o dos tratamentos t?rmicos variou de 60 a 15 minutos, para as temperaturas de 300 at? 1700? C respectivamente. Com o tratamento t?rmico ocorreu redu??o dr?stica da porosidade, crescimento do gr?o e aumento da translucidez da membrana. Para a caracteriza??o das membranas, foram feitas an?lises das propriedades: f?sica - termogravim?trica; difra??o de raios-X, ?rea superficial BET; morfol?gica - MEV, composicional atrav?s do EDS; e, ?ptica - transmit?ncia e absorb?ncia no UV-VIS e FTIR. Os resultados por meio do MEV mostraram que ocorreu cristaliza??o, densifica??o e mudan?as significativas na estrutura das membranas, bem como, a obten??o de microtubo; a an?lise de BET constatou uma diminui??o na ?rea superficial espec?fica das membranas que passou de 44,381m2.g-1, para menos de 1,8m2.g-1; na an?lise de transmit?ncia e absorb?ncia foi encontrado um valor de 16,5 % na faixa de 800nm, caracter?stico do infravermelho pr?ximo e no FTIR foram confirmadas os grupos moleculares do material. Assim, pode-se afirmar que as membranas apresentaram caracter?sticas mistas e propriedades que as qualificam para o uso em sistema de filtra??o de gases, bem como, de aplica??es ?ticas na faixa do comprimento de onda do Infravermelho, e como substrato de nanomateriais. Isto requer a continuidade e aprofundamento em estudos complementares
Libri sul tema "Membrane treatments"
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Michelle, Chapman-Wilbert, e Environmental Resources Team (U.S.). Water Treatment Engineering and Research Group., a cura di. Desalting and water treatment membrane manual: A guide to membranes for municipal water treatment. 2a ed. Denver, Colo: U.S. Dept. of Interior, Bureau of Reclamation, Technical Service Center, Water Treatment Engineering and Research, 1998.
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Peinemann, K. V. Membranes for water treatment. Weinheim: Wiley-VCH, 2010.
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Kislik, Vladimir S. Liquid membranes: Principles and applications in chemical separations and wastewater treatment. Amsterdam: Elsevier Science, 2009.
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Foundation, AWWA Research, Lyonnaise des eaux-Dumez (Firm) e South Africa. Water Research Commission., a cura di. Water treatment membrane processes. New York: McGraw-Hill, 1996.
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Shah, Maulin P. Membrane and Membrane-Based Processes for Wastewater Treatment. Boca Raton: CRC Press, 2023. http://dx.doi.org/10.1201/9781003165019.
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Professor, Stephenson Tom, a cura di. Membrane bioreactors for wastewater treatment. London: IWA, 2000.
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Pierre, Aimar, Aptel Philippe, European Society of Membrane Science and Technology. e Euromembrane 92 (1992 : Paris), a cura di. Membrane processes: Water treatment-pervaporation. Nancy: Groupe françaisede génie des procédés, 1992.
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J, Duranceau Steven, e American Water Works Association, a cura di. Membrane practices for water treatment. Denver, CO: American Water Works Association, 2001.
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Han, Xiaoyun. Di wen sheng wu mo ji qi wei sheng wu te xing de yan jiu. 8a ed. Ha'erbin Shi: Heilongjiang da xue chu ban she, 2009.
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Hillis, Peter, a cura di. Membrane Technology in Water and Wastewater Treatment. Cambridge: Royal Society of Chemistry, 2007. http://dx.doi.org/10.1039/9781847551351.
Testo completoCapitoli di libri sul tema "Membrane treatments"
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Fernández-Delgado, M., M. Coca, M. T. García-Cubero e S. Lucas. "Comparative study of membrane technology for recovery of humic substances". In WASTES: Solutions, Treatments and Opportunities IV, 83–88. London: CRC Press, 2023. http://dx.doi.org/10.1201/9781003345084-14.
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Krishna, V. M. V. Sai, e K. Prasanna. "A Review of the Pre-treatments that Are Used in Membrane Distillation". In Lecture Notes in Civil Engineering, 273–83. Singapore: Springer Nature Singapore, 2024. http://dx.doi.org/10.1007/978-981-99-6229-7_23.
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Fontana, José D., Cassandra G. Joerke, Madalena Baron, Marcelo Maraschin, Antonio G. Ferreira, Iris Torriani, A. M. Souza, Marisa B. Soares, Milene A. Fontana e Manoel F. Guimaraes. "Acetobacter Cellulosic Biofilms Search for New Modulators of Cellulogenesis and Native Membrane Treatments". In Biotechnology for Fuels and Chemicals, 327–38. Totowa, NJ: Humana Press, 1997. http://dx.doi.org/10.1007/978-1-4612-2312-2_28.
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Cui, Jiaxin, Mariluz Rojo Domingo, Ryan Konno, Claudia A. Manetti, George Kagugube, Oscar Odeigah e Joakim Sundnes. "Impact of Pathological Vascular Remodelling on Right Ventricular Mechanics". In Computational Physiology, 91–109. Cham: Springer Nature Switzerland, 2023. http://dx.doi.org/10.1007/978-3-031-25374-4_7.
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AbstractPulmonary arterial hypertension (PAH) is a rare disorder characterized by elevated blood pressure and pulmonary vascular resistance, often followed by right ventricular hypertrophy and heart failure. The effect of PAH and its treatments on the mechanics, function, and remodelling of the right ventricle (RV) is currently not well understood. To study cardiac biomechanics and functionality as PAH progresses, we implemented a computational model of the heart simulating right ventricular maladaptive remodelling. Our Windkessel-based model, which accounts for direct ventricular interaction and the presence of the pericardium, is utilized to simulate various disease stages of PAH. We find that the pericardium has a larger effect on heart performance than ventricular interaction through the septum.We also examined the effectiveness of two treatments, ventricular assist device (RVAD) and atrial septostomy, on diseased hearts. We show that while both pulsatile and continuous RVADs restore cardiac function, pulsatile RVAD improves cardiac output 29.4% more than continuous RVAD. We also demonstrate that atrial septostomy improves cardiac output by 19.5%. Our model can be further extended by simulating the heart’s response to other treatments such as extracorporeal membrane oxygenation (ECMO), and by incorporating ventricular remodelling growth simulations and finite-element ventricular modelling.
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Rajagopalan, Kishore. "Membrane Desalination". In Drinking Water Treatment, 55–91. Dordrecht: Springer Netherlands, 2011. http://dx.doi.org/10.1007/978-94-007-1104-4_4.
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Lehmann, Coline. "Working at Isotopentherapiestation D3: A Daily Challenge or Adventure Never Stops". In Beyond Becquerel and Biology to Precision Radiomolecular Oncology: Festschrift in Honor of Richard P. Baum, 197–200. Cham: Springer International Publishing, 2024. http://dx.doi.org/10.1007/978-3-031-33533-4_20.
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AbstractWorking at one of the largest Radio-Isotopentherapiestation in Germany is a real daily challenge. In addition to the standard therapies in nuclear medicine like treating benign and malignant thyroid diseases, there have been more than 7000 treatments in total performed with a very high number of peptide receptor radionuclide therapies (PRRT) in patients with neuroendocrine tumor as well as Lutetium-177 (Lu)-labeled prostate-specific membrane antigen radioligand therapies (Lu-PRLT) in metastatic castration-resistant prostate cancer (mCRPC) since 1997.On the one hand, the high number of patients is challenging; on the other hand, both the internationality and increasing multimorbidity of the patients coming to Bad Berka.This unique achievement of such a high number of treated patients is only possible when you are part of such a highly skilled and motivated team.
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Wang, Lawrence K., e Ravinder Menon. "Membrane Bioreactors". In Advanced Biological Treatment Processes, 129–56. Totowa, NJ: Humana Press, 2009. http://dx.doi.org/10.1007/978-1-60327-170-7_4.
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Chen, J. Paul, Honghui Mou, Lawrence K. Wang e Takeshi Matsuura. "Membrane Filtration". In Advanced Physicochemical Treatment Processes, 203–59. Totowa, NJ: Humana Press, 2006. http://dx.doi.org/10.1007/978-1-59745-029-4_7.
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Higuchi, A. "Blood Treatment Membrane". In Encyclopedia of Membranes, 1–3. Berlin, Heidelberg: Springer Berlin Heidelberg, 2014. http://dx.doi.org/10.1007/978-3-642-40872-4_73-3.
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Halim, Ahmad Sukari, Ehfa Bujang-Safawi e Arman Zaharil Mat Saad. "Amniotic Membrane in the Treatment of Burns". In Amniotic Membrane, 123–37. Dordrecht: Springer Netherlands, 2015. http://dx.doi.org/10.1007/978-94-017-9975-1_7.
Testo completoAtti di convegni sul tema "Membrane treatments"
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Boyles, J. K., JE B. Fox e M. C. Berndt. "THE DISTRIBUTION OF GP lb AND THE STABILITY OF THE PLASMA MEMBRANE ARE DEPENDENT UPON AN INTACT MEMBRANE SKELETON". In XIth International Congress on Thrombosis and Haemostasis. Schattauer GmbH, 1987. http://dx.doi.org/10.1055/s-0038-1643626.
Testo completoAbstract (sommario):
Platelets are know to have a cytoskeleton of actin filaments. We have presented evidence that they also have a membrane skeleton linked to the cytoskeletal filaments and that the membrane skeleton is linked to GP Ib-IX on the plasma membrane via actin-binding protein. In the current study, electron microscopy of thick (0.2 ym) epoxy sections was used to identify the distribution of GP lb. After various treatments, platelets were fixed and incubated with affinity-purified GP lb antibody and colloidal gold-labeled Protein-A. The entire cell surface was covered with a network of short intersecting chains of relatively evenly spaced gold particles. This was true of platelets in blood dripped directly from a vein into fixative, of washed discoid platelets, and of platelets activated by thrombin, ionophore, or cold under conditions in which aggregation did not occur. This pattern was not affected by the size of the gold label, the immunocytochemical protocol, or the fixative. The number of gold particles per cell was between 10,000 and 20,000, indicating a 1:1 ratio of label to GP lb. The distribution of GP lb was not affected by a level of cyto-chalasin B sufficient to disrupt the actin filaments of the platelet cytoskeleton. Proteolysis of actin-binding protein is known to be induced by treatment of platelets with dibucaine and by platelet activation (with either ionophore or thrombin) under conditions in which cell aggregation occurs. These same treatments caused GP lb to cluster. They also produced platelets with unstable membranes that vesiculated when the cells were subjected to shear force during centrifugation or osmotic-ally stressed during fixation. These studies show that both the distribution of GP lb and membrane stability are dependent upon the integrity of actin-binding protein and the membrane skeleton. In the high-shear environment of the blood vessel, the membrane skeleton and its linkage to GP Ib-IX and the cytoskeleton may be essential for proper platelet function.
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Mirbabayev, Miryusif, e Gulnar Bahramova. "Modern Methods of Purification of Heavy Metal Ions from Wastewater". In 2nd International Scientific-Practical Conference "Machine Building and Energy: New Concepts and Technologies". Switzerland: Trans Tech Publications Ltd, 2024. http://dx.doi.org/10.4028/p-5lxybv.
Testo completoAbstract (sommario):
Purification of heavy metal ions from wastewater is of prime importance for a clean environment and human health. Different reported methods were devoted to heavy metal ions removal from various wastewater sources. These methods could be classified into adsorption-, membrane-, chemical-, electric-, and photocatalytic-based treatments. This article reviews and discusses these methods in terms of used agents/adsorbents, removal efficiency, operating conditions, and the pros and cons of each method. Generally, it was noticed that most of the recent studies have focused on adsorption techniques. Even though the chemical and membrane methods are practical, the large-volume sludge formation and post-treatment requirements are vital issues that need to be solved for chemical techniques. Fouling and scaling inhibition could lead to further improvement in membrane separation.
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Tantawi, Khalid H., e Hope Hunnicutt. "Electrophysiology of Phosphatidylserine Bilayer Membranes Using Electrochemical Impedance Spectroscopy". In ASME 2021 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 2021. http://dx.doi.org/10.1115/imece2021-70808.
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Abstract In this work the electrical properties (resistance and capacitance) of the phospholipid phosphatidylserine, which was recently found to be the major constituent of plasma membranes of cancer cells that undergo chemotherapy, were measured using electrochemical impedance spectroscopy (EIS) in the frequency range 0.01 Hz to 100 kHz. The measurements show that the resistance of phosphatidylserine is 800 kω and the capacitance is approximately 90 pF. These numbers are significantly less than the reported resistance and capacitance of a lipid bilayer membrane that is composed primarily of phosphatidylethanolamine, which is the major constituent in plasma membranes in normal cells. Consequently, the results show that the electrical conductivity of the membranes of cancer cells increase significantly following chemotherapy treatments.
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Jiang, Yanfei, Guy M. Genin, Srikanth Singamaneni e Elliot L. Elson. "Interfacial Phases on Giant Unilamellar Vesicles". In ASME 2012 Summer Bioengineering Conference. American Society of Mechanical Engineers, 2012. http://dx.doi.org/10.1115/sbc2012-80942.
Testo completoAbstract (sommario):
Lipid nanodomains in cell membranes are believed to play a significant role in a number of critical cellular processes (Elson, et al., 2010). These include, for example, replication processes in enveloped viruses such as bird flu and HIV and signaling mechanisms underlying pathological conditions such as cancer. Due to the potential for developing new disease treatments through the control of these membrane rafts, the biophysics underlying their formation has been the subject of intense study, much of this focused on domain formation in giant unilamellar lipid vesicles (GUVs), a simplified model system.
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Ademiloye, A. S., L. W. Zhang e K. M. Liew. "Multiscale Meshfree Analysis of the Effects of Thermal Treatments on Deformability of Red Blood Cell Membrane". In 2016 IEEE 16th International Conference on Bioinformatics and Bioengineering (BIBE). IEEE, 2016. http://dx.doi.org/10.1109/bibe.2016.43.
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Paul, Brian K., e Dustin K. Ward. "Predicting the Hermeticity of Compression Seals in Microchannel Hemodialysers". In ASME 2014 International Manufacturing Science and Engineering Conference collocated with the JSME 2014 International Conference on Materials and Processing and the 42nd North American Manufacturing Research Conference. American Society of Mechanical Engineers, 2014. http://dx.doi.org/10.1115/msec2014-3941.
Testo completoAbstract (sommario):
Most end stage renal disease patients receive kidney hemodialysis three to four times per week at central medical facilities. At-home kidney dialysis increases the convenience and frequency of hemodialysis treatments which has been shown to produce better patient outcomes. One limiting factor in realizing home hemodialysis treatments is the cost of the hemodialyser. Microchannel hemodialysers produced using compression sealing techniques show promise for reducing the size and cost of hemodialysers. Challenges include the use of a 25 μm thick elastoviscoplastic mass transfer membrane for gasketing. This paper provides a framework for predicting the hermeticity of these compression seals. The mechanical properties of a Gambro AN69ST membrane are determined and used to establish limits on the dimensional tolerances of the polycarbonate laminae containing sealing boss used to seal the hemodialyser. The resulting methods are applied to the fabrication of a hemodialysis device showing constraints on the scaling of this method to larger device sizes. The resulting hemodialysis device is used to perform urea mass transfer experiments without leakage.
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Nguyen, Don. "Emerging Technologies for Treating Contaminants in Marine Wastewater". In ASME/USCG 2010 2nd Workshop on Marine Technology and Standards. American Society of Mechanical Engineers, 2010. http://dx.doi.org/10.1115/mts2010-0207.
Testo completoAbstract (sommario):
Contaminants in marine wastewater facing current or near-future regulations can be broadly categorized to free oil & suspended solids, emulsified oil and dissolved solids, and biological organisms. The first category of contaminants has been treated by commercially available OWS systems. The second class of contaminants, emulsified oils and dissolved solids, has been effectively treated by UF membrane filtration and to a less extent by biological oxidation and surface modified filters. A survey of recent advances in physical and chemical demulsification technologies to enhance emulsified oil removal with reduced loads on membrane was conducted. The study also identified new applications for treatments of biological organisms in ballast water. Paper published with permission.
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Guzmán, Amador M., e Cristina H. Amon. "Mass Transfer Enhancement in an Intravenous Membrane Oxygenator Induced by a Pulsating Balloon". In ASME 1999 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 1999. http://dx.doi.org/10.1115/imece1999-0572.
Testo completoAbstract (sommario):
Abstract The Intravenous Membrane Oxygentor (IMO) is a device that consists of hundreds of hollow fibers and an elastic, non-permeable, balloon that is positioned within the vena cava. The balloon inflates and deflates rhythmically to a given amplitude and frequency to generate cross flow, promote blood mixing, and enhance the gas exchange. The IMO has been designed to provide temporarily up to 50% of the O2 and CO2 exchange requirements to patients who suffer Acute Respiratory Distress Syndrome (ARDS) [1–4]. This illness affects approximately 150,000 people per year in the U.S. and is characterized by non-cardiogenic pulmonary edemas and a rapid and progressive malfunctioning of the lung [4]. The IMO device is an alternative therapy to conventional treatments such as mechanical ventilation and extracorporeal membrane oxygenation [5–7]. This paper reports the investigation of the flow and oxygen transfer characteristics of the IMO device shown in Fig. 1(a) and describes the numerically obtained flow patterns and the oxygen transfer characteristics for stationary and pulsating balloon regimes.
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Levin, G. E., e L. Santel. "ASSOCIATION OF PLASMINOGEN ACTIVATOR INHIBITOR(PAI-1) WITH THE MEMBRANE AND EXTRACELLULAR MATRIX OF HUMAN ENDOTHELIAL CELLS". In XIth International Congress on Thrombosis and Haemostasis. Schattauer GmbH, 1987. http://dx.doi.org/10.1055/s-0038-1644435.
Testo completoAbstract (sommario):
The cytosol, membrane-containing, and extracellular matrix(ECM) fractions of cultured human endothelial cells were isolated and analyzed for the presence and levels of PAI-1. Cells(4×106) released intact from the substratum had 70% (2.85±0.16 units)of their total inhibitor activity in the soluble portion of cell homogenate with the remaining activity(1.26±0.30 units) in the 100,000xg pellet.The ECM contained over twice as much activity as the total cellular inhibitor(9.82±0.35 units).Similar results were obtained with ECM after cell removal by 0.5% Na deoxycholate and hypotonic buffer treatment. Analysis of all three samples by SDS-PAGE and reverse fibrin autography showed inhibitor activity at an identical position on the gel corresponding to Mr=46000.Immunoblot analysis demonstrated that this inhibitor activity represented PAI-1. Inhibitor was not removed from the membrane by treatment with high salt, EDTA,divalent cations, low ionic strength buffer or sonication but was dissociated in the presence of detergents, guanidine HC1, or high pH. In contrast, ECM-associated PAI-1 was not affected by any of these treatments. Pulse-chase experiments indicated that the inhibitor was associated only transiently with the ECM in the presence of cells. None of the PAI-1 deposited during the labeling period was observed after 24 hrs. Incubation of the isolated ECM with protolytically active tPA resulted in a decline in the intensity of the Mr=46000 inhibitor band and the appearance of a Mr=44000 band and a Mr=110000 tPA-inhibitor complex band. Both of these bands were also found in the supernatent. The Mr=44000 band represented PAI-1 as shown by immunoprecipitation studies, although it did not contain anti-tPA activity.Thus, ECM-bound PAI-1 is susceptible to cleavage and release by tPA but does not in all cases form a stable complex with the protease. Elastase had a similar effect: following incubation, all of the PAI-1 was released from the ECM into the supernatent and was converted to the Mr=44000 inhibitor form. Collagenase, heparinase, and chondroitinase ABC had no effect. Therefore, PAI-1 is susceptible to inactivation and release from ECM by several proteases.
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Taskin, M. Ertan, Tao Zhang, Berry Gellman, Kurt A. Dasse, Bartley P. Griffith e Zhongjun J. Wu. "3D Flow Modeling and Blood Damage Characterization of the UltraMag™ Blood Pump". In ASME 2008 Summer Bioengineering Conference. American Society of Mechanical Engineers, 2008. http://dx.doi.org/10.1115/sbc2008-192105.
Testo completoAbstract (sommario):
Cardiovascular and lung diseases are the leading causes of death and disability worldwide. There are many therapies available for their treatment such as simple lifestyle changes, medicines, and surgical intervention or corrections. For the cases where the above treatments do not alleviate the patients’ conditions, the use of artificial devices may be the only option to treat or replace the diseased organ(s). However, the consideration of blood containing biomedical devices may introduce a prolonged contact between the blood and inorganic surfaces which induces variety of blood damages including hemolysis due to the creation of non-physiological mechanical shear stress field. Hemolysis is the release of hemoglobin from the red blood cells (RBC) as a result of the rupture of RBC membrane due to these unavoidable mechanical effects. For that reason, characterization of fluid dynamics and hemolytic performance is the key step to evaluate the design of biomedical devices.
Rapporti di organizzazioni sul tema "Membrane treatments"
1
Husson, Scott M., Viatcheslav Freger e Moshe Herzberg. Antimicrobial and fouling-resistant membranes for treatment of agricultural and municipal wastewater. United States Department of Agriculture, gennaio 2013. http://dx.doi.org/10.32747/2013.7598151.bard.
Testo completoAbstract (sommario):
This research project introduced a novel membrane coating strategy to combat biofouling, which is a major problem for the membrane-based treatment of agricultural and municipal wastewaters. The novelty of the strategy is that the membrane coatings have the unique ability to switch reversibly between passive (antifouling) and active (antimicrobial) fouling control mechanisms. This dual-mode approach differs fundamentally from other coating strategies that rely solely on one mode of fouling control. The research project had two complementary objectives: (1) preparation, characterization, and testing of dual-mode polymer nanolayers on planar surfaces and (2) evaluation of these nanolayers as membrane modifiers. The first objective was designed to provide a fundamental understanding of how polymer nanolayer chemistry and structure affect bacterial deposition and to demonstrate the reversibility of chemical switching. The second objective, which focused on membrane development, characterization, and testing, was designed to demonstrate methods for the production of water treatment membranes that couple passive and active biofouling control mechanisms. Both objectives were attained through synergistic collaboration among the three research groups. Using planar silicon and glass surfaces, we demonstrated using infrared spectroscopy that this new polymer coating can switch reversibly between the anti-fouling, zwitterion mode and an anti-microbial, quaternary amine mode. We showed that switching could be done more than 50 times without loss of activity and that the kinetics for switching from a low fouling zwitterion surface to an antimicrobial quaternary amine surface is practical for use. While a low pH was required for switching in the original polymer, we illustrated that by slightly altering the chemistry, it is possible to adjust the pH at which the switching occurs. A method was developed for applying the new zwitterionic surface chemistry onto polyethersulfone (PES) ultrafiltration membranes. Bacteria deposition studies showed that the new chemistry performed better than other common anti-fouling chemistries. Biofilm studies showed that PESultrafiltration membranes coated with the new chemistry accumulated half the biomass volume as unmodified membranes. Biofilm studies also showed that PES membranes coated with the new chemistry in the anti-microbial mode attained higher biofilm mortality than PES membranes coated with a common, non-switchablezwitterionic polymer. Results from our research are expected to improve membrane performance for the purification of wastewaters prior to use in irrigation. Since reduction in flux due to biofouling is one of the largest costs associated with membrane processes in water treatment, using dual-mode nanolayer coatings that switch between passive and active control of biofouling and enable detachment of attached biofoulants would have significant economic and societal impacts. Specifically, this research program developed and tested advanced ultrafiltration membranes for the treatment of wastewaters. Such membranes could find use in membrane bioreactors treating municipal wastewater, a slightly upgraded version of what presently is used in Israel for irrigation. They also may find use for pretreatment of agricultural wastewaters, e.g., rendering facility wastewater, prior to reverse osmosis for desalination. The need to desalinate such impaired waters water for unlimited agricultural use is likely in the near future.
2
Lurie, Susan, David R. Dilley, Joshua D. Klein e Ian D. Wilson. Prestorage Heat Treatment to Inhibit Chilling Injury and Delay Ripening in Tomato Fruits. United States Department of Agriculture, giugno 1993. http://dx.doi.org/10.32747/1993.7568108.bard.
Testo completoAbstract (sommario):
The research had two specific goals; (1) to develop and optimize a postharvest heat treatment and characterize the response of tomato to the heat and subsequent cold storage, and (2) to investigate the involvement of heat shock proteins (HSP) in resistance to chilling injury. For the first goal we have investigated many time-temperature treatments using dry heat and found that 48 h at 38oC is optimum for Israeli cultivars, while 48 h at 42oC worked better for American cultivars in preventing chilling injury. We have also compared hot water to hot air and found hot water to be effective, but less so than hot air. Membrane lipid composition in relation to chilling injury was investigated after hot water and hot air treatments. Investigation of fruit ripening found that mRNAs of ripening-related genes were inhibited by high temperature, but recovered during the subsequent storage period and allowed normal ripening to proceed. Sensory studies showed no difference in the taste of heated or nonheated fruit. Following the production of HSP in heated and stored fruit allowed us to determine that during low temperature storage the HSP remained present in the fruit tissue, and their presence was correlated with resistance to chilling injury. HSP clones have been isolated by both differential screening of a cDNA library of heated and chilled tomatoes (Israel) and by mRNA differential display (United States). These clones are being characterized.
3
Yahav, Shlomo, John Brake e Noam Meiri. Development of Strategic Pre-Natal Cycling Thermal Treatments to Improve Livability and Productivity of Heavy Broilers. United States Department of Agriculture, dicembre 2013. http://dx.doi.org/10.32747/2013.7593395.bard.
Testo completoAbstract (sommario):
The necessity to improve broiler thermotolerance and live performance led to the following hypothesis: Appropriate comprehensive incubation treatments that include significant temperature management changes will promote angiogenesis and will improve acquisition of thermotolerance and carcass quality of heavy broilers through epigenetic adaptation. It was based on the following questions: 1. Can TM during embryogenesis of broilers induce a longer-lasting thermoregulatory memory (up to marketing age of 10 wk) that will improve acquisition of thermotolerance as well as increased breast meat yield in heavy broilers? 2. The improved sensible heat loss (SHL) suggests an improved peripheral vasodilation process. Does elevated temperature during incubation affect vasculogenesis and angiogenesis processes in the chick embryo? Will such create subsequent advantages for heavy broilers coping with adverse hot conditions? 3. What are the changes that occur in the PO/AH that induce the changes in the threshold response for heat production/heat loss based on the concept of epigenetic temperature adaptation? The original objectives of this study were as follow: a. to assess the improvement of thermotolerance efficiency and carcass quality of heavy broilers (~4 kg); b. toimproveperipheral vascularization and angiogenesis that improve sensible heat loss (SHL); c. to study the changes in the PO/AH thermoregulatory response for heat production/losscaused by modulating incubation temperature. To reach the goals: a. the effect of TM on performance and thermotolerance of broilers reared to 10 wk of age was studied. b. the effect of preincubation heating with an elevated temperature during the 1ˢᵗ 3 to 5 d of incubation in the presence of modified fresh air flow coupled with changes in turning frequency was elucidated; c.the effect of elevated temperature on vasculogenesis and angiogenesis was determined using in ovo and whole embryo chick culture as well as HIF-1α VEGF-α2 VEGF-R, FGF-2, and Gelatinase A (MMP2) gene expression. The effects on peripheral blood system of post-hatch chicks was determined with an infrared thermal imaging technique; c. the expression of BDNF was determined during the development of the thermal control set-point in the preoptic anterior hypothalamus (PO/AH). Background to the topic: Rapid growth rate has presented broiler chickens with seriousdifficulties when called upon to efficiently thermoregulate in hot environmental conditions. Being homeotherms, birds are able to maintain their body temperature (Tb) within a narrow range. An increase in Tb above the regulated range, as a result of exposure to environmental conditions and/or excessive metabolic heat production that often characterize broiler chickens, may lead to a potentially lethal cascade of irreversible thermoregulatory events. Exposure to temperature fluctuations during the perinatal period has been shown to lead to epigenetic temperature adaptation. The mechanism for this adaptation was based on the assumption that environmental factors, especially ambient temperature, have a strong influence on the determination of the “set-point” for physiological control systems during “critical developmental phases.” Recently, Piestunet al. (2008) demonstrated for the first time that TM (an elevated incubation temperature of 39.5°C for 12 h/d from E7 to E16) during the development/maturation of the hypothalamic-hypophyseal-thyroid axis (thermoregulation) and the hypothalamic-hypophyseal-adrenal axis (stress) significantly improved the thermotolerance and performance of broilers at 35 d of age. These phenomena raised two questions that were addressed in this project: 1. was it possible to detect changes leading to the determination of the “set point”; 2. Did TM have a similar long lasting effect (up to 70 d of age)? 3. Did other TM combinations (pre-heating and heating during the 1ˢᵗ 3 to 5 d of incubation) coupled with changes in turning frequency have any performance effect? The improved thermotolerance resulted mainly from an efficient capacity to reduce heat production and the level of stress that coincided with an increase in SHL (Piestunet al., 2008; 2009). The increase in SHL (Piestunet al., 2009) suggested an additional positive effect of TM on vasculogenesis and angiogensis. 4. In order to sustain or even improve broiler performance, TM during the period of the chorioallantoic membrane development was thought to increase vasculogenesis and angiogenesis providing better vasodilatation and by that SHL post-hatch.
4
Mayes, Anne M., e Christopher E. Scott. Regenerative Polymer Membranes for Water Treatment Applications. Fort Belvoir, VA: Defense Technical Information Center, dicembre 2002. http://dx.doi.org/10.21236/ada404402.
Testo completo
5
Maribo, David W. Novel Membrane Separation System for Shipboard Oily Wastewater Treatment. Fort Belvoir, VA: Defense Technical Information Center, dicembre 2010. http://dx.doi.org/10.21236/ada544878.
Testo completo
6
Mar, Brenton G. Novel Membrane-Associated Targets for Diagnosis and Treatment of Breast Cancer. Fort Belvoir, VA: Defense Technical Information Center, maggio 2004. http://dx.doi.org/10.21236/ada427373.
Testo completo
7
Mar, Brenton G., e Carol A. Westbrook. Novel Membrane-Associated Targets for Diagnosis and Treatment of Breast Cancer. Fort Belvoir, VA: Defense Technical Information Center, maggio 2003. http://dx.doi.org/10.21236/ada417511.
Testo completo
8
Hibbs, Michael R., Susan Jeanne Altman, Yanshu Feng, Paul B. Savage, Jacob Pollard, Steven S. Branda, Darla Goeres et al. Linking ceragenins to water-treatment membranes to minimize biofouling. Office of Scientific and Technical Information (OSTI), gennaio 2012. http://dx.doi.org/10.2172/1034896.
Testo completo
9
Freeman, Benny D. Novel Nonporous Fouling-Resistant Enzymatic Composite Membranes for Waste Water Treatment. Fort Belvoir, VA: Defense Technical Information Center, agosto 2005. http://dx.doi.org/10.21236/ada436579.
Testo completo
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Hibbs, Michael R., Susan Jeanne Altman, Yanshu Feng, Paul B. Savage, Jacob Pollard, Andres L. Sanchez, Benjamin D. Fellows, Howland D. T. Jones e Lucas K. McGrath. Use of ceragenins to create novel biofouling resistant water-treatment membranes. Office of Scientific and Technical Information (OSTI), dicembre 2008. http://dx.doi.org/10.2172/946575.
Testo completo