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1
Kaplunov, J., L. I. Manevitch et V. V. Smirnov. « Vibrations of an elastic cylindrical shell near the lowest cut-off frequency ». Proceedings of the Royal Society A : Mathematical, Physical and Engineering Sciences 472, no 2189 (mai 2016) : 20150753. http://dx.doi.org/10.1098/rspa.2015.0753.
Texte intégralRésumé :
A new asymptotic approximation of the dynamic equations in the two-dimensional classical theory of thin-elastic shells is established for a circular cylindrical shell. It governs long wave vibrations in the vicinity of the lowest cut-off frequency. At a fixed circumferential wavenumber, the latter corresponds to the eigenfrequency of in-plane vibrations of a thin almost inextensible ring. It is stressed that the well-known semi-membrane theory of cylindrical shells is not suitable for tackling a near-cut-off behaviour. The dispersion relation within the framework of the developed formulation coincides with the asymptotic expansion of the dispersion relation originating from full two-dimensional shell equations. Asymptotic analysis also enables refining the geometric hypotheses underlying various ad hoc set-ups, including the assumption on vanishing of shear and circumferential mid-surface deformations used in the semi-membrane theory. The obtained results may be of interest for dynamic modelling of elongated cylindrical thin-walled structures, such as carbon nanotubes.
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Akbari, Ahmad, Vahid Reza Abbaspour et Seyed Majid Mojallali Rostami. « Tabas coal preparation plant wastewater treatment with membrane technology ». Water Science and Technology 74, no 2 (22 avril 2016) : 333–42. http://dx.doi.org/10.2166/wst.2016.192.
Texte intégralRésumé :
The goal of the present work is the Tabas coal preparation plant wastewater treatment using membrane technology. Polyacrylonitrile membrane was prepared through phase inversion method and then developed by annealing process. Also, high fouling resistance membranes were prepared by the embedding of TiO2 nanoparticles using self-assembling and blending methods. The effect of immersion time and TiO2 nanoparticles concentration was investigated using two techniques. The chemical structure, morphology, hydrophilicity, molecular weight cut-off and antifouling properties of membranes were characterized using energy-dispersive X-ray spectroscopy, scanning electron microscopy, contact angle, polyethylene glycol tracers, and cationic polyacrylamide (C-PAM) filtration, respectively. The optimized self-assembled membrane was shown to have more than 31.2% higher water flux with the best antifouling properties. Improving hydrophilicity leads to excellent antifouling properties for composite membranes and illustrates a promising method for fabrication of high performance membrane for C-PAM separation.
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Kertész, Szabolcs, T. B. De Freitas et Cecília Hodúr. « Characterization of polymer membranes by contact angle goniometer ». Analecta Technica Szegedinensia 8, no 2 (12 mai 2014) : 18–22. http://dx.doi.org/10.14232/analecta.2014.2.18-22.
Texte intégralRésumé :
The wider applications of all membrane separation processes have a main obstacle, namely the fouling phenomena, which have to be understood in more details. Surface properties, hydrophilic and hydrophobic characteristics of a polymer membrane can be determined by measuring the contact angle. The hydrophilicity of a membrane has an important influence on its performances, like permeate flux, membrane rejection or membrane fouling characteristics. In our work the contact angles of three kinds of typically commercial ultrafiltration (UF-PES-4), nanofiltration (NE-90) and reverse osmosis (LFC-30) membranes were firstly investigated and compared by contact angle goniometer measurements. The relationships between the contact angles were researched by well considering the effects of membrane sample pretreatments by distilled water prewetting and water droplet volume. Furthermore, the effects of prewetting, water droplet contact time on different molecular weight cut-off ultrafiltration membranes’ surface and droplet pH on the contact angle values were also investigated. Moreover, fresh, clean and dry, as well as pretreated, and fouled UF membranes were also measured and compared.
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Naseer, Danyal, Jang-Hoon Ha, Jongman Lee, Chanhyuk Park et In-Hyuck Song. « Effect of the Peptization Process and Thermal Treatment on the Sol-Gel Preparation of Mesoporous α-Alumina Membranes ». Membranes 12, no 3 (10 mars 2022) : 313. http://dx.doi.org/10.3390/membranes12030313.
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Compared to traditional membrane materials, alumina membranes are particularly beneficial for industrial wastewater treatment. However, the development of mesoporous α-alumina membranes for ultrafiltration applications is still a challenge due to uncontrolled pore size. In this study, we optimized the sol-gel method for the fabrication of a high-performance mesoporous α-alumina membrane. The peptization conditions (pH and peptization time) and phase transformation of boehmite were investigated to achieve better properties of the α-alumina membrane. The surface properties of the membrane were observed to be improved by reducing the system pH to 3.5 and increasing the peptization time to 24 h. The effect of sintering temperature on the phase transformation behavior, microstructures and performance of the membranes was also elucidated. An α-alumina ultrafiltration membrane with an average thickness of 2 μm was obtained after sintering at 1100 °C. The molecular weight cut-off of the α-alumina membrane, as obtained by the filtration of aqueous PEG solution, was approximately 163 kDa (12.5 nm). This is the smallest pore size ever reported for pure α-alumina membranes.
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Akbari, Ahmad, Zahra Fakharshakeri et Sayed Majid Mojallali Rostami. « A novel positively charged membrane based on polyamide thin-film composite made by cross-linking for nanofiltration ». Water Science and Technology 73, no 4 (26 octobre 2015) : 776–89. http://dx.doi.org/10.2166/wst.2015.538.
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In this paper, a novel positively charged membrane was prepared through interfacial polymerization technique between polyethyleneimine in aqueous phase and trimesoyl chloride in organic phase. Next, cross-linking of polyamide (PA) layer using ρ-xylylene dichloride (XDC) and glutaraldehyde (GA) was studied. The influences of cross-linking concentrations on the separation and permeation performance of membrane were also investigated. Membranes were characterized in terms of their chemical structure, the cross-sectional and surface morphologies, contact angles, molecular weight cut-off (MWCO) and effect of pH feed solution. The salt rejection sequence of CaCl2 >NaCl > Na2SO4 showed a positive charge at the membrane surface after cross-linking reaction. The MWCO of primary PA membrane decreased from 1,135 to 775 and 885 Da for XDC and GA, respectively. XDC membrane shows highest CaCl2 divalent cationic rejection (95.5%) and lowest water flux (21.1 L/m2.h). This study illustrates a promising method for fabrication of positively charged membrane in cation separation.
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Gomes, Elson Dinis, P. C. R. Pinto et Alírio E. Rodrigues. « Lignin Valorization : Concentration of Model Phenolic Compounds by Nanofiltration ». U.Porto Journal of Engineering 3, no 1 (26 mars 2018) : 72–78. http://dx.doi.org/10.24840/2183-6493_003.001_0007.
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Lignin is a biopolymer found in plants which can be valorized as a source of value added compounds by breaking its structure in the constituting monomers. A model solution was prepared with seven phenolic compounds, including vanillin and syringaldehyde, usually found after alkaline lignin oxidation. The model solution was concentrated by nanofiltration membranes with low molecular weight cut-off (MWCO). Two membranes (DOW NF270 and KOCH MPS-34) were tested for permeate fluxes and phenolic compound rejection. Significant reduction of the volume mixture was achieved with high permeate fluxes as well as high rejections (above 90%) for the phenolic compounds studied. The membrane with the best performance was the DOW NF270 with maintained high rejections while having higher permeate fluxes resulting in higher productivity when compared with the other membrane KOCH MPS-34 also tested.
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et al., Alsayer. « Effect of membrane mean pore diameter on water and solute flux in forward osmosis processes ». International Journal of ADVANCED AND APPLIED SCIENCES 9, no 11 (novembre 2022) : 99–105. http://dx.doi.org/10.21833/ijaas.2022.11.012.
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Several forward osmosis (FO) experiments were carried out using aqueous solutions of sodium chloride (NaCl) in different concentrations, as draw solution (DS), and freshwater, as feed water (FW). The experiments were conducted at a constant temperature of ~20°C and using a symmetric cellulosic membrane in two grades different in their values of the molecular weight cut-off (MWCO), which is related to the mean pore diameter. This study investigates the effect of the membrane mean pore diameter on water flux and DS solute diffusional flux across the membrane. The value of water flux indicates the performance of the FO process, while solute flux is an important factor that determines its practicality. A proportionality factor is used to specify the relationship between water flux and solute flux for each membrane type and operational conditions. The results of this study show that water flux and solute flux increase as the solute concentration difference across the membrane increases. It is also found that, in the range of the tested membranes, membranes with larger mean pore diameters have lower water flux and higher solute flux.
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Chen, Yee-An, Shuo-Ming Ou et Chih-Ching Lin. « Influence of Dialysis Membranes on Clinical Outcomes : From History to Innovation ». Membranes 12, no 2 (26 janvier 2022) : 152. http://dx.doi.org/10.3390/membranes12020152.
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Dialysis membranes were traditionally classified according to their material compositions (i.e., as cellulosic or synthetic) and on the basis of the new concept of the sieving coefficient (determined by the molecular weight retention onset and molecular weight cut-off). The advantages of synthetic polymer membranes over cellulose membranes are also described on the basis of their physical, chemical, and structural properties. Innovations of dialysis membrane in recent years include the development of medium cutoff membranes; graphene oxide membranes; mixed-matrix membranes; bioartificial kidneys; and membranes modified with vitamin E, lipoic acid, and neutrophil elastase inhibitors. The current state of research on these membranes, their effects on clinical outcomes, the advantages and disadvantages of their use, and their potential for clinical use are outlined and described.
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Kovpak, A. A., Yu Yu Ivin, A. N. Piniaeva, Yu Kh Khapchaev, S. V. Ozherelkov, A. V. Belyakova et A. A. Ishmukhametov. « Application of ultrafiltration membranes for purification and concentration of Sabin poliovirus type 1 ». Journal of microbiology, epidemiology and immunobiology 98, no 2 (5 mai 2021) : 135–43. http://dx.doi.org/10.36233/0372-9311-94.
Texte intégralRésumé :
Introduction. Since the development of inactivated polio vaccines, different stages of the production process have been changed and improved. Current production of inactivated polio vaccines based on both wild and attenuated strains includes several technological stages, one of which is the concentration of the virus-containing liquid, which ensures poliovirus concentration, and purification of the virus-containing liquid from a significant part of the ballast components.Research objective is to compare the characteristics of ultrafiltration membranes and select the membranes that provide optimal value of purification and concentration of poliovirus type 1 (Sabin strain).Materials and methods. Laboratory ultrafiltration systems from two manufacturers with 50, 100, and 300 kDa membranes were used for the concentration. Results were evaluated by the content of total protein, which is the main stress for the subsequent purification stages, the value of infectious virus titer in the concentrate, and the content of D-antigen as the target product.Results and discussion. Obtained results demonstrated that the content of the target product (the highest D-antigen content) and purification from impurity proteins (the total protein content in the concentrate) were most optimal when a membrane with a cut-off of 300 kDa was used for concentration. The study also evaluated the real cut-off components by various membranes to determine the composition of the protein load on the target product.Conclusion. In terms of quality of the resulting target product and the manufacturability of the production process, the use of a 300 kDa membrane is the most appropriate when working out the technology for manufacturing inactivated polio vaccine based on Sabin strains of poliovirus and the Vero line as a producing culture.
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Gardiner, James D., Jonathan R. Codd et Robert L. Nudds. « An association between ear and tail morphologies of bats and their foraging style ». Canadian Journal of Zoology 89, no 2 (février 2011) : 90–99. http://dx.doi.org/10.1139/z10-096.
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Most studies relating bat morphology to flight ecology have concentrated on the wing membrane. Here, canonical variance analysis showed that the ear and tail morphologies of bats also strongly relate to foraging strategy, which in turn is correlated with flight style. Variations in tail membrane morphology are likely to be a trade-off between increases in the mechanical cost of flight and improvements in foraging and flight performance. Flying with large ears is also potentially energetically expensive, particularly at high flight speeds. Large ears, therefore, are only likely to be affordable for slow foraging gleaning bat species. Bats with faster foraging flight styles tend to have smaller ears, possibly to cut the overall drag produced and reduce the power required for flight. Variations in the size of ears and tail membranes appear to be driven primarily by foraging strategy and not by body size, because the scaling relationships found are either weak or not significant. Ear size in bats may be a result of a trade-off between acoustic and aerodynamic performance.
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Urbanowska, Agnieszka, et Małgorzata Kabsch-Korbutowicz. « The Use of Flat Ceramic Membranes for Purification of the Liquid Fraction of the Digestate from Municipal Waste Biogas Plants ». Energies 14, no 13 (1 juillet 2021) : 3947. http://dx.doi.org/10.3390/en14133947.
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Due to the rising water deficit in agriculture, digestate is increasingly being considered not only as an alternative fertiliser but also as a potential source of water. The use of recycled water for crop irrigation requires that it be treated in such a way that contaminants from the fermented biomass are not returned to the environment. Membrane processes can provide promising results in this regard. This study seeks to achieve membrane filtration using flat ceramic membranes for effective digestate liquid fraction treatment from a municipal waste biogas plant. Membranes of 1, 5, 15, and 50 kDa, and 0.14 and 0.45 µm are examined. The results obtained show that the application of a sedimentation process, as a preliminary step in the purification of the digestate, allows for a significant reduction in the content of contaminants in the solution. By analysing the effectiveness of the liquid fraction of the digestate purification in the sedimentation-membrane filtration process using flat ceramic membranes, it can be stated that all the membranes tested can be applied in the digestate purification. With an increase in the cut-off value, a deterioration in the quality of the digestate can be observed. The use of the sedimentation process before the membrane process not only improves the final quality of the digestate but also reduces the intensity of membrane fouling.
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Nastouli, Alexandra, Asimina Tsirigka, Michael Harasek, Anastasios J. Karabelas et Sotiris I. Patsios. « The Effect of Heat Sterilization on Key Filtration Performance Parameters of a Commercial Polymeric (PVDF) Hollow-Fiber Ultrafiltration Membrane ». Membranes 12, no 8 (22 juillet 2022) : 725. http://dx.doi.org/10.3390/membranes12080725.
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Membrane processes can be integrated with fermentation for the selective separation of the products from the fermentation broth. Sterilization with saturated steam under pressure is the most widely used method; however, data concerning heat sterilization applicability to polymeric ultrafiltration (UF) membranes are scarcely available. In this study, the effect of the sterilization process on the filtration performance of a commercial polyvinylidene difluoride (PVDF) hollow fiber UF membrane was evaluated. Membrane modules were constructed and sterilized several times in an autoclave. Pure water flux tests were performed, to assess the effect of heat sterilization on the membrane’s pure water permeance. Dextran rejection tests were performed for the characterization of membrane typical pore size and its fouling propensity. Filtration performance was also assessed by conducting filtration tests with real fermentation broth. After repeated sterilization cycles, pure water permeance remained quite constant, varying between approx. 830 and 990 L·m−2·h−1·bar−1, while the molecular weight cut-off (MWCO) was estimated to be in the range of 31.5–98.0 kDa. Regarding fouling behavior, the trans-membrane pressure increase rate was stable and quite low (between 0.5 and 7.0 mbar/min). The results suggest that commercial PVDF UF membranes are a viable alternative to high-cost ceramic UF membranes for fermentation processes that require heat sterilization.
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Hidalgo, A. M., M. Gómez, M. D. Murcia, M. Serrano, R. Rodríguez-Schmidt et P. A. Escudero. « Behaviour of polysulfone ultrafiltration membrane for dyes removal ». Water Science and Technology 77, no 8 (17 mars 2018) : 2093–100. http://dx.doi.org/10.2166/wst.2018.124.
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Abstract Although ultrafiltration membranes have been used for the separation of macromolecules and colloids from solutions, this process has a limited application in the removal of dyes present in coloured discharges of textile industry, as these typically have much lower molecular weight than the molecular cut-off of the membranes (MWCO). In the present work, we have evaluated the behaviour of a polysulfone ultrafiltration membrane in the removal of different dyes from aqueous solutions (Congo red, methyl green and amaranth). Different variables (tangential flow rate, concentration of dye and pH of the feed) were studied to determine their influence on the separation processes (permeate flux and rejection coefficient). The results show that Congo red is easily removed with a GR60PP membrane (MWCO = 25 kDa), whereas methyl green and amaranth show rejection coefficient values of approximately 25.78% and 13.85%, respectively, at neutral pH. Also, an interesting effect is observed for the rejection coefficient for methyl green at different pH values. In addition, several treatments were performed to the membrane so as to modify its surface, trying to improve the values obtained for permeate flux and rejection rate.
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Suhalim, Nur Syahirah, Norherdawati Kasim, Ebrahim Mahmoudi, Intan Juliana Shamsudin, Abdul Wahab Mohammad, Fathiah Mohamed Zuki et Nor Laili-Azua Jamari. « Rejection Mechanism of Ionic Solute Removal by Nanofiltration Membranes : An Overview ». Nanomaterials 12, no 3 (27 janvier 2022) : 437. http://dx.doi.org/10.3390/nano12030437.
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The toxicity of heavy metals can cause water pollution and has harmful effects on human health and the environment. Various methods are used to overcome this pressing issue and each method has its own advantages and disadvantages. Membrane filtration technology such as nanofiltration (NF) produces high quality water and has a very small footprint, which results in lower energy usage. Nanofiltration is a membrane-based separation technique based on the reverse osmosis separation process developed in the 1980s. NF membranes have a pore size of 1 nm and molecular weight cut off (MWCO) of 300 to 500 Da. The properties of NF membranes are unique since the surface charge of the membranes is dependent on the functional groups of the membrane. The rejection mechanism of NF membrane is unique as it is a combination of various rejection mechanisms such as steric hindrance, electric exclusion, dielectric effect, and hydration mechanism. However, these mechanisms have not been studied in-depth due to their complexity. There are also many factors contributing to the rejection of NF membrane. Many junior researchers would face difficulty in studying NF membrane. Therefore, this paper is designed for researchers new to the field, and will briefly review the rejection mechanisms of NF membrane by both sieving and non-sieving separation processes. This mini-review aims to provide new researchers with a general understanding of the concept of the separation process of charged membranes.
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Rajewska, Paulina, Jolanta Janiszewska et Jakub Rajewski. « Integration of Ultra- and Nanofiltration for Potato Processing Water (PPW) Treatment in a Circular Water Recovery System ». Membranes 13, no 1 (3 janvier 2023) : 59. http://dx.doi.org/10.3390/membranes13010059.
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The article analyzes integrated ultrafiltration (UF) and nanofiltration (NF) processes for potato processing wastewater treatment for the purpose of which a laboratory filtration system for flat sheet membranes with the effective surface area of 1.4 × 10−2 m2 (UF: polysulfone, cut-off: 10,000 Da; NF: polypiperazine amide, cut-off: 150–300 Da) was used. As part of the study, the effect of the transmembrane pressure of UF (0.2 MPa and 0.4 MPa) and NF (1.0 MPa and 1.8 MPa) on the permeate flux and rejection coefficient was investigated and the impact of sewage preparation methods on the degree of pollution reduction was determined. Moreover, a method for a fouling layer removal from the UF membranes is also proposed. The results of the analyses conducted by the authors show that the pretreatment stage offers additional advantages to TSS and turbidity removal. In both cases (0.2 and 0.4 MPa), UF used after the pretreatment process resulted in a 97–99% reduction in these impurities. The analysis of the determined rejection coefficients shows that the use of NaOH and H2O2 for the regeneration of the UF membrane has a positive effect on filtration efficiency. Regarding NF, the rejection coefficients for most tested parameters were higher for the 1.8 MPa process compared to 1.0 MPa, and approximately 80% of water was recovered.
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Melin, E., T. Leiknes, H. Helness, V. Rasmussen et H. Ødegaard. « Effect of organic loading rate on a wastewater treatment process combining moving bed biofilm and membrane reactors ». Water Science and Technology 51, no 6-7 (1 mars 2005) : 421–30. http://dx.doi.org/10.2166/wst.2005.0664.
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The effect of moving bed biofilm reactor (MBBR) loading rate on membrane fouling rate was studied in two parallel units combining MBBR and membrane reactor. Hollow fiber membranes with molecular weight cut-off of 30 kD were used. The HRTs of the MBBRs varied from 45 min to 4 h and the COD loading rates ranged from 4.1 to 26.6 g COD m−2 d−1. The trans-membrane pressure (TMP) was very sensitive to fluxes for the used membranes and the experiments were carried out at relatively low fluxes (3.3–5.6 l m−2 h−1). Beside the test with the highest flux, there were no consistent differences in fouling rate between the low- and high-rate reactors. Also, the removal efficiencies were quite similar in both systems. The average COD removal efficiencies in the total process were 87% at 3–4 h HRT and 83% at 0.75–1 h HRT. At high loading rates, there was a shift in particle size distribution towards smaller particles in the MBBR effluents. However, 79–81% of the COD was in particles that were separated by membranes, explaining the relatively small differences in the removal efficiencies at different loading rates. The COD fractionation also indicated that the choice of membrane pore size within the range of 30 kD to 0.1 μm has very small effect on the COD removal in the MBBR/membrane process, especially with low-rate MBBRs.
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D. Fazullin, Dinar, Elena A. Kharitonova, Aisilu M. Gimadieva et Gennady V. Mavrin. « Improvement of Effectiveness of Separation of Emulsion by Processing Ptfe Membrane with Microwave Radiation ». International Journal of Engineering & ; Technology 7, no 4.7 (27 septembre 2018) : 193. http://dx.doi.org/10.14419/ijet.v7i4.7.20542.
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In this work, in order to increase the productivity and degree of separation of petroleum emulsions, a modification of thin-film microfiltration membranes from polytetrafluoroethylene (PTFE) by ultrahigh-frequency (microwave) radiation in the decimeter wave band in air, nitrogen and argon was carried out. Treatment of membranes with microwave radiation leads to a reduction in the mass of PTFE membranes depending on the treatment time and the gaseous media. The membrane weight decreases most strongly to 0.17% when treated in atmospheric air, which is apparently due to the aggressive action of oxygen. The least mass of the membrane decreases when treated in argon, only 0.06%. The increase in the specific productivity of membranes during processing in the atmosphere of atmospheric air is explained by the hydrophilization of the surface, due to the formation of polar oxygen-containing groups. A decrease in specific productivity when treated in an argon inert gas environment occurs apparently due to crosslinking of the surface layer. Treatment of the membrane in a nitrogen medium increases the degree of emulsion separation by 6.9%, in air media by 15.3%, in argon media by 21%. An increase in the efficiency of separation of emulsions is also confirmed by a decrease in the size of oil particles in filtrates of emulsions. So the limiting size of the particles of the disperse phase cut off by the initial membrane was 118 nm, and the membrane treated with microwave radiation in the air medium was 39 nm, in the nitrogen medium 68 nm and in argon medium 10 nm.
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Niestroj-Pahl, Robert, Lara Stelmaszyk, Ibrahim M. A. ElSherbiny, Hussein Abuelgasim, Michaela Krug, Christian Staaks, Greta Birkholz et al. « Performance of Layer-by-Layer-Modified Multibore® Ultrafiltration Capillary Membranes for Salt Retention and Removal of Antibiotic Resistance Genes ». Membranes 10, no 12 (6 décembre 2020) : 398. http://dx.doi.org/10.3390/membranes10120398.
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Polyether sulfone Multibore® ultrafiltration membranes were modified using polyelectrolyte multilayers via the layer-by-layer (LbL) technique in order to increase their rejection capabilities towards salts and antibiotic resistance genes. The modified capillary membranes were characterized to exhibit a molecular weight cut-off (at 90% rejection) of 384 Da. The zeta-potential at pH 7 was −40 mV. Laboratory tests using single-fiber modified membrane modules were performed to evaluate the removal of antibiotic resistance genes; the LbL-coated membranes were able to completely retain DNA fragments from 90 to 1500 nt in length. Furthermore, the pure water permeability and the retention of single inorganic salts, MgSO4, CaCl2 and NaCl, were measured using a mini-plant testing unit. The modified membranes had a retention of 80% toward MgSO4 and CaCl2 salts, and 23% in case of NaCl. The modified membranes were also found to be stable against mechanical backwashing (up to 80 LMH) and chemical regeneration (in acidic conditions and basic/oxidizing conditions).
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Yammine, Sami, Robin Rabagliato, Xavier Vitrac, Martine Mietton Peuchot et Rémy Ghidossi. « The use of nanofiltration membranes for the fractionation of polyphenols from grape pomace extracts ». OENO One 53, no 1 (13 février 2019) : 11–26. http://dx.doi.org/10.20870/oeno-one.2019.53.1.2342.
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Filtration experiments in batch concentration mode (with recycling of the retentate stream) of grape pomace extract were performed in laboratory filtration membrane equipment by using nine commercial nanofiltration (NF) membranes with an approximate molecular weight cut-off (MWCO) of 1000‒150 Da. The filtration experiments of the selected pomace extract were performed by modifying the most important operating variables: transmembrane pressure, tangential velocity, temperature, and the nature and MWCO of the membranes. The evolution of the cumulative permeate volumes and permeate fluxes with processing time was analyzed till a volume reduction factor (VRF) of 10 was reached. The effect of the mentioned operating conditions was discussed. The effectiveness of the filtration treatments was determined by the evaluation of the rejection coefficients for several families of polyphenols. Membranes possessing MWCO between 1000 and 500 Da were able to quantitatively recover polymeric proanthocyanidins in the concentrate stream and separate them from phenols that passed through the membrane into the permeate stream. On the other hand, the 600 to 300 Da membranes could also be used for the fractionation of monomeric phenolic families. The membranes were able to partially remove the anthocyanin fragments of phenolic acid derivatives and flavonols in the concentrate stream and at the same time.
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Zheng, Jun, et Wei Zhou. « Membrane Separation Assisted One-Pot Synthesis of Hydroxyapatite Nanorods ». Advanced Materials Research 779-780 (septembre 2013) : 251–54. http://dx.doi.org/10.4028/www.scientific.net/amr.779-780.251.
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In the current paper, hydroxyapatite (HAP) nanorods have been synthesized via a precipitation method with membrane separation technique assisted. The reactants were Ca(NO3)2 ·4H2O, NH4H2PO4 and ammonia water. The synthesized HAP nanocrystals were characterized by X-ray diffraction (XRD) and transmission electron microscopy (TEM) measurements. Patterns of XRD exhibit that the products are indexed high-quality hexagonal crystal system nanocrystals. Though the TEM pictures, large quantities of HAP nanorods could be observed with a length of about 50-80nm and a diameter of about 10-20 nm. Preliminary study on the membrane based purifing process is also discussed by comparion the membrane of molecular weight cut-off 6000 to 10000. The resulting HAP nanorods have extensive use in biomedical area such as the bone graft substitute, drug delivery system, carrier for gene transfection, and etc.
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Abidin, Nur Sofuwani Zainul, Siti Aslina Hussain et Siti Mazlina Mustapa Kamal. « Removal of Lactose from Highly Goat’s Milk Concentration through Ultrafiltration Membrane ». Applied Mechanics and Materials 625 (septembre 2014) : 596–99. http://dx.doi.org/10.4028/www.scientific.net/amm.625.596.
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Concentration of goat milk using cross-flow filtration unit with 10KDa molecular weight cut off (MCWO)-sized ultrafiltration membrane was examined under various operating conditions. The parameters to be optimized are trans-membrane pressure (TMP) and cross-flow velocity. Permeate flux is decreased with time due to fouling of the membrane. The localized membrane fouling may be reduced by increasing the feed flow rate and TMP to mitigate overall membrane fouling. By doing so, the transmission of lactose will also increase. The aim is to produce concentrated goat milk with minimal lactose content and thus high concentration of protein. Spray-drying method is used to convert the concentrated non-lactose milk obtained into milk powder. The milk powder then was characterized in terms of its surface particle, solubility, and nutritional content with the well-commercialized non-lactose milk. This project tackles understanding to minimize the deposition rates of particles on membrane by optimizing the involved parameters and be proved by comparing the yield obtained with well-commercialized non-lactose milk. Keywords:Goat’s milk, lactose intolerance, ultrafiltration, spray dry,membrane, concentration
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Gaglianò, Martina, Carmela Conidi, Giuseppina De Luca et Alfredo Cassano. « Partial Removal of Sugar from Apple Juice by Nanofiltration and Discontinuous Diafiltration ». Membranes 12, no 7 (15 juillet 2022) : 712. http://dx.doi.org/10.3390/membranes12070712.
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Partial removal of sugars in fruit juices without compromising their biofunctional properties represents a significant technological challenge. The current study was aimed at evaluating the separation of sugars from phenolic compounds in apple juice by using three different spiral-wound nanofiltration (NF) membranes with a molecular weight cut-off (MWCO) in the range of 200–500 Da. A combination of diafiltration and batch concentration processes was investigated to produce apple juice with reduced sugar content and improved health properties thanks to the preservation and concentration of phenolic compounds. For all selected membranes, permeate flux and recovery rate of glucose, fructose, and phenolic compounds, in both diafiltration and concentration processes, were evaluated. The concentration factor of target compounds as a function of the volume reduction factor (VRF) as well as the amount of adsorbed compound on the membrane surface from mass balance analysis were also evaluated. Among the investigated membranes a thin-film composite membrane with an MWCO of 200–300 Da provided the best results in terms of the preservation of phenolic compounds in the selected operating conditions. More than 70% of phenolic compounds were recovered in the retentate stream while the content of sugars was reduced by about 60%.
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Bubela, H. S., V. V. Konovalova, I. S. Kolesnyk et A. F. Burban. « Modification of the surface of polyvinylidene fluoride membranes with polyethyleneimine ». Himia, Fizika ta Tehnologia Poverhni 13, no 1 (30 mars 2022) : 94–104. http://dx.doi.org/10.15407/hftp13.01.094.
Texte intégralRésumé :
PVDF membranes are extensively applied in ultrafiltration processes of aqueous solutions of different chemical substances owing to its outstanding properties, such as high mechanical strength, thermal stability, and chemical resistance. However, hydrophobicity of this polymer largely limits the practical application of PVDF. Therefore, it is very important to develop methods of modifying the surface of PVDF membranes with the aim to improve their properties. Polyethyleneimine, as a modifying agent, has already been investigated for hydrophilization of the surface. However, the modification process leads to reduction of the volumetric flow and changes of the membrane selectivity because polymer is grafted not only to the surface, but also into the pores of the membranes, reducing their effective radius. Taking everything into account, this investigation is devoted to the development of a technique for surface modification of PVDF membranes with PEI (with pre-filling of pores) to improve their transport properties, at the same time preserving the morphology of the membrane and its characteristics. Nonionic surfactant Tetronic® 701 is used as a pore-filling agent. Commercial ultrafiltration PVDF membranes (with cut-off of 150 kDa) were firstly activated with a carbonate buffer, then the pores were filled with Tetronic® 701, further surface modification of membranes with PEI was performed. The modification process was confirmed by IR spectroscopy. The surface properties of the membranes were studied by scanning electron microscopy. The changes in the hydrophilicity of the modified membranes were studied by measuring the wetting angles of the membrane surface with water, glycerol, and diiodomethane. The transport properties of the membrane were experimentally studied in the process of ultrafiltration of aqueous protein solution (in particular, lysozyme, lipase, BSA); water permeability coefficients and protein rejection coefficients were determined. It was found that the usage of Tetronic® 701 during the membrane modification process allowed improving the water permeability coefficient compared to the membrane modified without pre-filling the pores; hydrophilization of the surface reduced the effect of concentration polarization.
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Dencheva-Zarkova, M., J. Genova et I. Tsibranska. « Effect of pressure and cross-flow velocity on membrane behaviour in red wine nanofiltration ». Journal of Physics : Conference Series 2436, no 1 (1 janvier 2023) : 012013. http://dx.doi.org/10.1088/1742-6596/2436/1/012013.
Texte intégralRésumé :
Abstract Nanofiltration has found numerous applications in winemaking industry as an effective separation technology, allowing for the recovery and concentration of valuable bioactive compounds from wine/grape by-products, as well as for wine dealcoholization. However, the assessment of membrane fouling remains essential for a stable and sustainable membrane operation. Because of its complex nature, wine components (colloids and solutes such as polysaccharides, polyphenols, proteins) contribute to different mechanisms of fouling. The increase of fouling propensity as well as the conditions that contribute to it - transmembrane pressure and cross-flow velocity – are studied in the present study. Quantitative characteristics as fouling indices are discussed. Results with red wine (Mavrud) nanofiltration are obtained using two NF membranes - Nadir® NP030 P (asymmetric polyethersulfone (PES), MWCO 500 Da) and Alfa Laval NF99HF (thin film composite polyester, MWCO 200 Da). Nanofiltration runs were carried out by a constant-pressure cross-flow filtration system MaxiMem, Prozesstechnik GmbH with a rectangular flat-sheet membrane of 215 cm2 active area. Effect of transmembrane pressure (TMP) (10 to 50 bar) and cross-flow rate (1-3 l/min) on the permeate flux are discussed in view of membrane fouling. Higher operating pressures enhance the permeate flux but may also lead to increased fouling. The two membranes show very different permeate fluxes, the ones measured with NF99HF being 10-20 times higher. Increase in cross-flow velocity improves the hydrodynamic conditions such as shear stress field close to the membrane. The expected positive effect on permeate flux is the more noticeable the more pronounced the fouling. This was shown by two polymer membranes of different molecular weight cut-off exhibiting different susceptibility to fouling.
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Kerr, Keith, Erik Thunnissen, Urania Dafni, Alex Soltermann, Stephen P. Finn, Lukas Bubendorf, Eric Verbeken et al. « Prevalence and clinical correlation of programmed cell death 1 ligand (PD-L1) expression in patients with resected non-small cell lung cancer (NSCLC) : Results from the European Thoracic Oncology Platform (ETOP) Lungscape cohort. » Journal of Clinical Oncology 35, no 15_suppl (20 mai 2017) : 8516. http://dx.doi.org/10.1200/jco.2017.35.15_suppl.8516.
Texte intégralRésumé :
8516 Background: Conflicting data exists on the potential prognostic impact of PD-L1 expression in NSCLC. The Lungscape project, a fully annotated large biobank of resected stage I-III NSCLC, allows detailed analysis of this issue. Methods: Prevalence of PD-L1 positivity and its association with clinicopathological characteristics and patient outcome - Relapse-free Survival (RFS), Time-to-Relapse (TTR) and Overall Survival (OS) - was explored in the ETOP Lungscape cohort. PD-L1 expression was assessed on tissue microarrays (TMAs) using the DAKO 28-8 immunohistochemistry assay. Positivity cut-off points of ≥1%, 5% and 50% for neoplastic cell membrane staining were considered. Results: PD-L1 data were available for 2182 patients, from 15 ETOP centers, with median follow-up 4.8 years; 1191 patients still alive; median age 66 years; 64% male, 32/54/11% for current/former/never smokers; 49/29/22% for stages I/II/III; 51/42/4/3% adenocarcinomas (AC)/squamous cell (SCC) /large cell and sarcomatoid (LCS)/other. Median RFS/TTR/OS were 53/99/69 months (AC: 52/84/72, SCC: 54/not reached/64; and LSC 52/103/74). PD-L1 prevalence with 1% cut-off was, overall: 43%, 95% confidence interval (95%CI): 41-46; (AC: 42%, 95%CI: 39-46; SCC: 44%, 95%CI: 40-47; and LCS: 53%, 95%CI: 42-65), while for 5% threshold, prevalence was 34%, 95%CI: 32-36. PD-L1 1% positivity was a significant predictor only for AC: HRRFS: + vs - = 0.82; 95%CI: 0.69-0.97, HRTTR: + vs - = 0.83; 95%CI: 0.68-1.01, HROS: + vs -= 0.83; 95%CI: 0.69-1.01 (adjusted p = 0.024, 0.064, 0.063 respectively). This effect is found also for the 5% cut-off, and preserved in the overall model including all histologies. Using the 50% cut-off, PD-L1 positivity was detected in 17% of patients; 95%CI: 15-18, but was no longer a significant predictor of outcome, overall and by histology type. Conclusions: PD-L1 positivity (1% and 5% cut-offs) was present in more than one third of resected NSCLC and was associated with a better prognosis for AC patients.
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Tian, Huali, Xing Wu et Kaisong Zhang. « Polydopamine-Assisted Two-Dimensional Molybdenum Disulfide (MoS2)-Modified PES Tight Ultrafiltration Mixed-Matrix Membranes : Enhanced Dye Separation Performance ». Membranes 11, no 2 (30 janvier 2021) : 96. http://dx.doi.org/10.3390/membranes11020096.
Texte intégralRésumé :
Tight ultrafiltration (TUF) membranes with high performance have attracted more and more attention in the separation of organic molecules. To improve membrane performance, some methods such as interface polymerization have been applied. However, these approaches have complex operation procedures. In this study, a polydopamine (PDA) modified MoS2 (MoS2@PDA) blending polyethersulfone (PES) membrane with smaller pore size and excellent selectivity was fabricated by a simple phase inversion method. The molecular weight cut-off (MWCO) of as-prepared MoS2@PDA mixed matrix membranes (MMMs) changes, and the effective separation of dye molecules in MoS2@PDA MMMs with different concentrations were obtained. The addition amount of MoS2@PDA increased from 0 to 4.5 wt %, resulting in a series of membranes with the MWCO values of 7402.29, 7007.89, 5803.58, 5589.50, 6632.77, and 6664.55 Da. The MWCO of the membrane M3 (3.0 wt %) was the lowest, the pore size was defined as 2.62 nm, and the pure water flux was 42.0 L m−2 h−1 bar−1. The rejection of Chromotrope 2B (C2B), Reactive Blue 4 (RB4), and Janus Green B (JGB) in aqueous solution with different concentrations of dyes was better than that of unmodified membrane. The separation effect of M3 and M0 on JGB at different pH values was also investigated. The rejection rate of M3 to JGB was higher than M0 at different pH ranges from 3 to 11. The rejection of M3 was 98.17–99.88%. When pH was 11, the rejection of membranes decreased with the extension of separation time. Specifically, at 180 min, the rejection of M0 and M3 dropped to 77.59% and 88.61%, respectively. In addition, the membrane had a very low retention of salt ions, Nacl 1.58%, Na2SO4 10.52%, MgSO4 4.64%, and MgCl2 1.55%, reflecting the potential for separating salts and dyes of MoS2@PDA/PES MMMs.
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Shaikhiev, I. G., V. O. Dryakhlov, M. F. Galikhanov, D. D. Fazullin et G. V. Mavrin. « Separation of oil emulsion using polyacrylonitrile membranes, modified by corona discharge ». Perspektivnye Materialy, no 11 (2020) : 30–37. http://dx.doi.org/10.30791/1028-978x-2020-6-30-37.
Texte intégralRésumé :
It is investigated the influence of the parameters of the unipolar corona discharge (the treatment time, voltage) on the performance and selectivity of separation of model emulsions “oil in water” based on the oil in the Devonian deposits Tomatocage field (Republic of Tatarstan) using polyacrylonitrile membranes with a molecular weight cut-off of 60 kDa particles. Determined COD values of the original emulsions and filtrates. The values of the processing time (30 seconds) and voltage of the corona (5 kV) membranes, which achieved the best performance and selectivity of the separation process of oil-water emulsion. Sitting drop methods, x-ray diffraction and atomic force microscopy showed changes of the surface structure and internal structure of treated membrane. In particular, there was decrease in the wetting angle from 45.1 to 43.3 and an increase in the degree of crystallinity from 0.15 to 0.18, which is due to the flow on the surface of PES membrane processes of etching and oxidation resulting from exposure to a unipolar corona discharge ozone, which is also confirmed by images of the surface of the filter elements and the histograms of the topography, based on which it showed a decrease in height and number of protrusions from 42 nm and 7500 to 10 nm and 2500.
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Nelli, Erin M., Thomas P. Loughran, Kim Leitzel, Suhail M. Ali, Lawrence Demers, Walter P. Carney, Peter J. Hamer et Allan Lipton. « Elevated Serum Ras Levels in Patients with LGL Leukemia. » Blood 108, no 11 (16 novembre 2006) : 4457. http://dx.doi.org/10.1182/blood.v108.11.4457.4457.
Texte intégralRésumé :
Abstract Background: Ras is a GDP/GTP binding G protein that acts as a molecular switch converting signals from the cell membrane to the nucleus to regulate cell proliferation, differentiation, and protein synthesis. Activation of ras oncogenes has been identified in a variety of cancers, including 30% of patients with acute myelogenous leukemia (AML). Large granular lymphocyte (LGL) leukemia is a clonal T-cell lymphoproliferative disorder associated with chronic neutropenia, anemia, or autoimmune diseases, particularly rheumatoid arthritis. The purpose of this study was to evaluate serum ras levels in patients with LGL leukemia. Methods: A novel ras p21 ELISA (Oncogene Science/Bayer HealthCare) employing two monoclonal antibodies was utilized to quantify ras levels in baseline serum obtained from 32 patients with LGL leukemia. A control group of 48 healthy subjects was also used to establish a cutoff for the upper limit of normal for serum ras levels. A 95% non-parametric cut-off was used to determine significant differences in the frequency of elevated serum ras levels in control vs. LGL leukemia patients. Results: The median serum ras level in the 48 healthy control subjects was 125 pg/mL, with a 5% to 95% range of 50–422 pg/mL. The upper limit of normal for serum ras was defined as 422 pg/mL, as determined using the 95 % non-parametric cut-off. In the LGL leukemia patient group, 19 of 32 patients (59 %) had elevated baseline serum ras levels (median 484 pg/mL) (p=0.0001) when utilizing the healthy control upper limit of normal cut-off value. Conclusions: The results of this study indicate that the majority of LGL leukemia patients have significantly elevated serum ras levels when compared to healthy controls. Serum ras should be evaluated as a potential biomarker in larger leukemia trials, especially for response to treatment with inhibitors of the ras signaling pathway.
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Raskin, Jean-Pierre. « SOI Technologies from Microelectronics to Microsystems — Meeting the More than Moore Roadmap Requirements ». International Journal of High Speed Electronics and Systems 25, no 01n02 (mars 2016) : 1640004. http://dx.doi.org/10.1142/s0129156416400048.
Texte intégralRésumé :
This last decade Silicon-on-Insulator (SOI) MOSFET technology has demonstrated its potentialities for high frequency, reaching cut-off frequencies close to 500 GHz for nMOSFETs, and for harsh environments (high temperature, radiation) commercial applications. SOI also presents high resistivity substrate capabilities, leading to substantially reduced substrate losses and non-linearities. More recently, SOI technology has been emerging as a major contender for heterogeneous microsystems applications. In this work, we demonstrate the advantages of SOI technology for Radio Frequency CMOS integration as well as for building thin film sensors on thin dielectric membrane and three-dimensional micro-electro-mechanical (MEMS) sensors and actuators cointegrated with their associated SOI CMOS circuitry.
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Bilginaylar, Kani. « Uncommon Odontogenic Orocutaneous Fistula of the Jaw Treated with Platelet-Rich Fibrin ». Case Reports in Dentistry 2017 (2017) : 1–5. http://dx.doi.org/10.1155/2017/7174217.
Texte intégralRésumé :
Orocutaneous fistula (OCF) of dental origin is a relatively rare condition and continues to be a challenging diagnosis. Misdiagnosis of OCF usually leads to unnecessary and noneffective treatment. A 21-year-old male referred with a complaint of a lesion on the chin which was misdiagnosed as a carbuncle (lesion of nonodontogenic origin) by a physician. After radiological examination, there was a lesion around the apical region of right central incisor. These findings indicated a sinus tract associated with dental origin. After root canal treatment, apical surgery was performed and platelet-rich fibrin (PRF) was administered to the cavity of the lesion as a gel form to improve healing and also used as a membrane form to cut off the relation between infected area and the skin. All procedures were performed intraorally; no extraoral intervention was performed. Three months later, clinical and radiological examination showed total healing without scar formation. The key to successful treatment of OCF is accurate diagnosis. Additionally, the use of PRF after surgical interventions is an effective and innovative therapy to improve healing.
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Tran, Mai Lien, Ying-Shr Chen et Ruey-Shin Juang. « Fouling Analysis in One-Stage Ultrafiltration of Precipitation-Treated Bacillus subtilis Fermentation Liquors for Biosurfactant Recovery ». Membranes 12, no 11 (28 octobre 2022) : 1057. http://dx.doi.org/10.3390/membranes12111057.
Texte intégralRésumé :
Primary recovery of surfactin from precipitation-pretreated fermentation broths of Bacillus subtilis ATCC 21332 culture by one-stage dead-end and cross-flow ultrafiltration (UF) was studied. Dead-end experiments were first performed to select suitable conditions, including the amount of added ethanol—a micelle-destabilizing solvent (0–70 vol%), type (polyethersulfone, polyacrylonitrile, poly(vinylidene fluoride)) and molecular-weight cut-off (MWCO, 30–100 kDa) of the membrane in the surfactin concentration range of 0.25–1.23 g/L. Then, the cross-flow UF experiments were conducted to check the recovery performance in the ranges of feed surfactin concentration of 1.13–2.67 g/L, flow velocity of 0.025–0.05 m/s, and transmembrane pressure of 40–100 kPa. The Hermia model was also used to clarify membrane fouling mechanisms. Finally, three cleaning agents and two in situ cleaning ways (flush and back-flush) were selected to regain the permeate flux. As for the primary recovery of surfactin from the permeate in cross-flow UF, a polyethersulfone membrane with 100-kDa MWCO was suggested, and the NaOH solution at pH 11 was used for membrane flushing.
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Seo, G. T., T. S. Lee, B. H. Moon, K. S. Choi et H. D. Lee. « Membrane separation activated sludge for residual organic removal in oil wastewater ». Water Science and Technology 36, no 12 (1 décembre 1997) : 275–82. http://dx.doi.org/10.2166/wst.1997.0457.
Texte intégralRésumé :
A hybrid membrane separation activated sludge process was investigated for treatment of residual organic matter in oily wastewater from an automobile engine manufacturing plant. A bench scale experiment was conducted to identify the biodegradability of the residual organic matter in activated sludge reactors at various HRT (equal to SRT), such as 5, 10, 20, 30 days. Removal efficiency of higher than 90% was obtained in terms of SCOD at more than 10 day HRT showing the possibility of biological treatment. Ultrafiltration test was also carried out for the residual organics using cross-flow membrane filtration system at transmembrane pressure (TMP) of 2.0 kg/cm2. The membrane used for this experiment was polysulfone hollow fiber membrane with 30,000 molecular weight cut off. The rejection rate was around 10% in terms of TCOD. This low rejection rate explains that the residual organics in the oil wastewater are soluble and their MWCO size distribution might be less than 30,000. However the combined membrane activated sludge process could maintain significantly high removal efficiency more than 95% for the residual organics in the oily wastewater. The enhancement in organic removal was estimated to be contributed to the increased biomass in the system resulting in the reduction of the organic loading.
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Goslan, Emma H., Derek Wilson, Jenny Banks, Peter Hillis, Andrew Campbell et Simon A. Parsons. « Natural organic matter fractionation : XAD resins versus UF membranes. An investigation into THM formation ». Water Supply 4, no 5-6 (1 décembre 2004) : 113–19. http://dx.doi.org/10.2166/ws.2004.0099.
Texte intégralRésumé :
An increase in reservoir water colour over the last 10 years has been impacting on the ability of water treatment works (WTWs) in the UK to meet THM regulations. The problem is exacerbated in autumn particularly after heavy rainfall. It appears that residual organics are labile precursors to disinfection by-products (DBPs). One WTW was investigated to determine a link between raw water characteristics and reactivity with chlorine. Bulk water parameters were measured but the information obtained was limited. To further characterise the water, samples of reservoir water were fractionated using XAD resins and UF membranes. The resulting fractions were subjected to analysis of dissolved organic carbon (DOC), UV absorbance at 254 nm (UV254), specific UV absorbance (SUVA) defined as the ratio of UV254 to DOC and trihalomethane formation potential (THM-FP). The samples were also characterised using high performance size exclusion chromatography (HPSEC). Both methods of fractionation described here have limitations in explaining the bulk water behaviour. The relationship between SUVA and THM-FP was discussed. HPSEC showed that the size distribution of the resin separated and membrane separated fractions was similar indicating that the molecular weight cut-off (MWCO) of the membranes is not sharp.
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Hofmann, Katrin, et Christof Hamel. « Screening and Scale-up of Nanofiltration Membranes for Concentration of Lactose and Real Whey Permeate ». Membranes 13, no 2 (31 janvier 2023) : 173. http://dx.doi.org/10.3390/membranes13020173.
Texte intégralRésumé :
In dairy industry huge quantities of whey accumulate as a by-product. In particular the containing lactose was not produced profitably in the past. Thus, the trend goes towards modification and sustainable use of lactose for which a concentration step is required. Nanofiltration (NF) has shown to be a good choice since partial demineralization can be realized in parallel. Therefore, in this study, 10 commercial polymer NF membranes were studied in detail and systematically for their suitability to concentrate lactose, with the proviso of high flux and high to complete rejection. Preliminary trials were conducted with flat-sheet membranes and a lactose model solution and the influence of transmembrane pressure (TMP), temperature and lactose concentration was studied. Finally, results were evaluated by using spiral wound modules and real industrial whey permeate. The results offered that a membrane screening is essentially since no correlation between molecular weight cut-off (MWCO) and permeate flow could be found. The conclusions found for the lactose model solution were in good agreement with the whey permeate, but as the ions contribute to the osmotic pressure of the feed the deviations increase in the course of concentration since ions are also partly retained.
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C. C., Amruta, et Hema A. Patil. « Correlation between amniotic fluid lamellar body concentrations at different gestational ages and respiratory distress syndrome ». International Journal of Reproduction, Contraception, Obstetrics and Gynecology 8, no 1 (26 décembre 2018) : 188. http://dx.doi.org/10.18203/2320-1770.ijrcog20185421.
Texte intégralRésumé :
Background: Respiratory distress syndrome (RDS) also known as hyaline membrane disease is the most common cause of respiratory failure in neonates. The risk of RDS rises in prematurity due to decreased production of surfactant. Lamellar bodies (LB) are storage form of surfactant and are actively secreted into the alveolar space and hence into the amniotic fluid. The objective of the present study was to find out correlation between amniotic fluid lamellar body concentrations (LBC) at different gestational ages and respiratory distress syndromeMethods: The study was a prospective observational study conducted over a period of 1 year at department of OBG, SDM college of medical sciences, Dharwad. All women undergoing caesarean section were included in the study. 5 ml of amniotic fluid was collected at the time of Caesarean section and sent to laboratory, Lamellar body concentrations (LBC) was counted in auto analyzer by platelet impedance counting. Incidence of RDS at different gestational age with an LBC cut off 40,500 was calculated.Results: Among 300 patients studied, Respiratory distress was seen in 116 (41.3%) of patients. LBC cut off of 40,500 was chosen. Out of 140 preterm babies, 121 (86.8%) had lamellar body count less than 40,500 and 19 (13.5%) had more than 40,500. There is significant correlation between decreasing lamellar body count in preterms and increasing incidence of RDS.Conclusions: LBC count increases with increasing gestational ages and is inversely proportional to the incidence of RDS in preterm newborns.
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Pizzo, P., P. Zanovello, V. Bronte et F. Di Virgilio. « Extracellular ATP causes lysis of mouse thymocytes and activates a plasma membrane ion channel ». Biochemical Journal 274, no 1 (15 février 1991) : 139–44. http://dx.doi.org/10.1042/bj2740139.
Texte intégralRésumé :
Extracellular ATP (ATPo) caused a concentration-dependent lysis of mouse thymocytes. Lysis, as judged by release of the cytosolic enzyme lactate dehydrogenase, was preceded by depolarization of the plasma membrane and by Ca2+ influx. Both Na+ uptake (which sustained plasma membrane depolarization) and Ca2+ influx showed (1) the same dependence on the ATPo concentration; (2) the same nucleotide specificity; and (3) the same Hill coefficient. However, whereas the rise in the cytosolic free Ca2+ concentration ([Ca2+]i) was fully inhibited by the known Ca2+ blocker verapamil, plasma membrane depolarization was enhanced under these conditions. Plasma membrane depolarization was greater and was shifted to lower ATPo concentrations in the absence of extracellular Ca2+ (Ca2+o), whereas the rise in [Ca2+]i was greater in Na(+)-free media. Plasma membrane depolarization also occurred in Na(+)-free choline- or methylglucamine-containing media, and was potentiated by chelation of free divalent ions with EDTA, supporting previous reports pointing to ATP4-as the active species. Among a number of purine and pyrimidine nucleotides, only adenosine 5′-[gamma-thio]triphosphate and ADP were partially effective. Furthermore, ethidium bromide (Mr 380), Lucifer Yellow (Mr 463) and Eosin Yellowish (Mr 692) did not permeate through the ATPo-activated channel. These findings suggest that lytic effects of ATPo in mouse thymocytes depend on the activation of a membrane channel with low selectivity for cations and an Mr cut-off of 200.
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Poplin, Elizabeth, Harpreet Wasan, Lindsey Rolfe, Mitch Raponi, Tone Ikdahl, Ihor Bondarenko, Irina Davidenko et al. « Randomized multicenter, phase II study of CO-101 versus gemcitabine in patients with metastatic pancreatic ductal adenocarcinoma (mPDAC) and a prospective evaluation of the of the association between tumor hENT1 expression and clinical outcome with gemcitabine treatment. » Journal of Clinical Oncology 31, no 15_suppl (20 mai 2013) : 4007. http://dx.doi.org/10.1200/jco.2013.31.15_suppl.4007.
Texte intégralRésumé :
4007 Background: Gemcitabine requires membrane transporter proteins to cross the cell membrane. Low expression of the human equilibrative nucleoside transporter-1 (hENT1) may play a role in gemcitabine resistance in PDAC. CO-101 (also known as CP-4126), a lipid-drug conjugate of gemcitabine, was rationally designed to enter cells independently of hENT1 and to circumvent transporter-mediated resistance. We conducted a randomized, controlled trial (LEAP) in patients with mPDAC to determine whether CO-101 improved survival vs gemcitabine in patients with low hENT1 tumors. The study also prospectively tested the hypothesis that gemcitabine is more active in patients with hENT1 high than hENT1 low tumors in metastatic disease. Methods: Patients were randomized to CO-101 or gemcitabine. An immunohistochemistry test measuring tumor hENT1 expression was developed in parallel with the recruitment phase of LEAP. To dichotomize the population, a hENT1 cut-off was defined using primary PDAC tumor samples from an adjuvant trial. LEAP participants provided a metastasis sample during screening for blinded hENT1 assessment, and the cut-off was applied to these samples. The primary endpoint of the study was overall survival in the low hENT1 subgroup. Results: 367 patients were enrolled, with metastasis hENT1 status available for 358/367 (97.5%). 232/357 (65%) were hENT1 low. There was no difference in overall survival between CO-101 and gemcitabine in the hENT1 low subgroup, or overall, with hazard ratios of 0.994 [95% CI 0.746, 1.326] and 1.072 [95% CI 0.856, 1.344] respectively. Within the gemcitabine arm, there was no difference in survival between the hENT1 high and low subgroups (HR 1.147 95% CI 0.809, 1.626). The observed side effect profile was typical of gemcitabine and was similar in both treatment arms, in the hENT1 low subgroups and overall. Conclusions: CO-101 is not superior to gemcitabine in patients with mPDAC and low tumor hENT1 expression. Metastasis hENT1 expression did not predict gemcitabine treatment outcome in patients with mPDAC. Clinical trial information: NCT01124786.
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Balgobin, Sanjeet, Marion Morena, Vincent Brunot, Noemie Besnard, Delphine Daubin, Laura Platon, Romaric Larcher et al. « Continuous Veno-Venous High Cut-Off Hemodialysis Compared to Continuous Veno-Venous Hemodiafiltration in Intensive Care Unit Acute Kidney Injury Patients ». Blood Purification 46, no 3 (2018) : 248–56. http://dx.doi.org/10.1159/000489082.
Texte intégralRésumé :
Aims: High cut-off (HCO) continuous veno-venous hemodialysis (CVVHD) was compared to high-flux membrane (HFM) continuous veno-venous hemodiafiltration (CVVHDF) in intensive care unit (ICU) acute kidney injury (AKI) in terms of efficiency, hemodynamic tolerance, medium-sized molecules removal, albumin loss, and inflammatory system activation. Methods: In a prospective cross-over randomized study, 10 AKI patients underwent successively HCO (Ultraflux EmiC2: β2-microglobulin [β2M] sieving coefficient [SC]: 0.9) CVVHD and HFM (Ultraflux AV1000S: β2M SC: 0.65) CVVHDF. Results: Over the 20 sessions, hypotensive and febrile episodes, reduction rates of urea, creatinine, and β2M were similar in both modalities. Though dialysis dose was higher with CVVHDF (36 ± 4 vs. 21 ± 6 mL/Kg/h), urea, creatinine, and β2M instantaneous and plasmatic clearances did not differ except for urea at 12 h. Protein loss, superoxide anion production, cytokines, and growth factors variations were also comparable. Conclusion: HCO CVVHD is well tolerated and is as effective as HFM CVVHDF in clearance of solutes and removal of β2M. It induces neither protein loss nor overproduction of superoxide anion. Video Journal Club “Cappuccino with Claudio Ronco” at http://www.karger.com/?doi=489082.
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Proudfoot, D., D. P. Parrott et D. E. Bowyer. « A dialysis culture system for the study of the production and modulation of growth-regulatory molecules : studies using the P388D1 macrophage cell line ». Journal of Cell Science 108, no 1 (1 janvier 1995) : 379–86. http://dx.doi.org/10.1242/jcs.108.1.379.
Texte intégralRésumé :
P388D1 macrophage-like cells have previously been shown to produce both mitogenic and inhibitory regulators of porcine smooth muscle cell (pSMC) growth. The mitogenic activity was shown to have a molecular mass of > 10 kDa while the inhibitory activity was in the range of 2–6 kDa. In the present study, we present a novel dialysis culture system where P388D1 cells were grown in dialysis membranes with a 12 kDa cut-off which allowed continuous production of fractions of the culture medium. Using pSMC as target cells, mitogenic activity was found to be retained by the dialysis membrane while the low molecular mass inhibitory activity passed freely through the membrane. The effect of the macrophage-activators phorbol myristate acetate (PMA), concanavalin A (ConA) and interferon-gamma in combination with lipopolysaccharide (IFN gamma/LPS) were investigated in the dialysis culture system. PMA, ConA and IFN gamma/LPS were found to enhance the production of mitogenic activity by P388D1 cells. PMA also increased the production of growth-inhibitory activity, while ConA abolished inhibitor production and IFN gamma/LPS had no effect on the amount of inhibitory activity produced by P388D1 cells. The experiments show that the balance of production of mitogenic and inhibitory activities by macrophages can be modulated by agents that alter the state of activation of the cells. This could be of profound significance in the influence of macrophages on smooth muscle cell growth during the development of atherosclerosis.
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Trouve, E., V. Urbain et J. Manem. « TREATMENT OF MUNICIPAL WASTEWATER BY A MEMBRANE BIOREACTOR : RESULTS OF A SEMI-INDUSTRIAL PILOT-SCALE STUDY ». Water Science and Technology 30, no 4 (1 août 1994) : 151–57. http://dx.doi.org/10.2166/wst.1994.0180.
Texte intégralRésumé :
Membrane bioreactors (MBR) represent a new generation of processes that can be applied to the treatment of municipal and industrial wastewater. Their main advantage is their ability to keep all biomass in the bioreactor, thus removing all suspended solids from the treated water and disinfecting it according to the membrane cut-off threshold. Perfect control as well as separation of hydraulic (HRT) and biomass retention times (SRT) also means better control of biological activity. Treatment of municipal wastewater on a semi-industrial aerobic pilot-scale MBR (HRT: 24 hr; SRT: 25 days) resulted in complete nitrification and from 93 to 99.9% removal of COD, N-NH3 and suspended solids. The COD removed loading rate was equal to 0.2 kg/kg VSS.day and the average sludge production was around 0.2 kgSS/kgCOD. Filtration through 0.1 µm ceramic hollow fibres (Surface = 1.1 m2) under moderate conditions (1.5 to 3.5 m/s; TMP < 2 bars) maintained good flow rates of 60 to 80 1/hr at 20°C for over 15 days without chemical washing. The performances shown here over a total period of 100 days emphasize perfect stability of the MBR process in treating municipal wastewater.
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Wang, Zhe, Jing Wen Xue, Ji Shi Zhang et Wen Xia Liu. « Ultrafiltration Treatment and Physical Properties of Ammonia Sulfite Pulping Liquor of Wheat Straw ». Advanced Materials Research 560-561 (août 2012) : 909–13. http://dx.doi.org/10.4028/www.scientific.net/amr.560-561.909.
Texte intégralRésumé :
Ammonia sulfite pulping liquor of wheat straw was treated by ultrafiltration. Experimental results indicated that the membrane with a cut-off of 10kDa was suitable for concentrating wheat straw liquor and had good anti-fouling property against pulping liquor. Permeability of ash turn higher with the increasing of volume reduction at the operating condition of 200 kPa and 25°C, and retentate was concentrated when volume reduced. Influences of ultrafiltration on physical properties of ammonia sulfite pulping liquor and its retentate after ultrafiltration were studied. Results showed that retentate had better performances as surfactant, concrete additive and dispersant. Surface tension of 1% lignin solution of retentate was 54.7 mN/m, which was lower than that of the untreated original lignosulfonate by 2.2 mN/m. Dispersing effect of retentate on cement was also investigated, it was found that flowability of neat cement paste improved from 70mm to 102mm.
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Ratnadewi, Anak Agung Istri, Kamelia Rizqi Fauziyah et Dwi Indarti. « Purification of Xylooligosaccharide From Casavva Pulp by Ultrafiltration Method ». BERKALA SAINSTEK 9, no 2 (21 juillet 2021) : 51. http://dx.doi.org/10.19184/bst.v9i2.23388.
Texte intégralRésumé :
Xylan is the main component of hemicellulose. Xylan can be extracted from agricultural waste, such as cassava pulp. Xylan is used as an endo-β-1,4-D-xylanase substrate to produce impure xylooligosaccharides (XOS)This study aims to purify XOS from cassava pulp using the ultrafiltration method. The components of XOS obtained from the enzymatic hydrolysis were analyzed using thin layer chromatography (TLC) and densitometry methods. In addition, the XOS was purified by the ultrafiltration method using a cellulose membrane with a Molecular Weight Cut Off (MWCO) of 12 kDa. The permeate obtained from the purification results was also analyzed using TLC and densitometry. The results of this study indicated that the components in XOS cassava pulp before and after purification by the TLC method were X5 and X6, while the XOS components before and after purification by the densitometric method were X3, X4 and X5.
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Loizzo, Monica, Vincenzo Sicari, Rosa Tundis, Mariarosaria Leporini, Tiziana Falco et Vincenza Calabrò. « The Influence of Ultrafiltration of Citrus limon L. Burm. cv Femminello Comune Juice on Its Chemical Composition and Antioxidant and Hypoglycemic Properties ». Antioxidants 8, no 1 (16 janvier 2019) : 23. http://dx.doi.org/10.3390/antiox8010023.
Texte intégralRésumé :
Membrane separation has brought about a significant change in the food processing industry because it could operate separation at low temperature without a reduction of nutrients and bioactive compounds. Citrus limon L. Burm. cv Femminello comune juice, an Italian IGP (Protected Geographical Indication) product, was subjected to the ultrafiltation (UF) process using a cellulose acetate membrane, with a cut-off of 100 kDa, subjected to different transmembrane pressures (TMP, 05–1.5 bar). Untreated and ultra-filtrated (UF) juices were investigated for physicochemical parameters including pH, titratable acidity (TA), total soluble solids (TSS) and ascorbic acid content. Total phenols (TPC) and flavonoids (TFC) contents were also determined. Rutin, hesperidin, eriocitrin, and neohesperidin were selected as markers and quantified by HPLC. Antioxidant potential was investigated by using DPPH, ABTS, and FRAP tests. RACI was used to identify the sample with highest antioxidant potential. The hypoglycemic activity was examined using carbohydrates hydrolyzing enzymes assay. The application of increasing pressures across the membrane led to a reduction in TSS without causing a loss of bioactive compounds in terms of TPC and TFC. UF juice obtained with TMP of 1.5 bar (J3) showed a significant amount of eriocitrin and hesperidin with concentrations of 15.8 and 10.5 mg/100 mL, respectively. This sample showed the highest antioxidant potential and exhibited a promising α-amylase and α-glucosidase inhibitory activity with IC50 values of 31.1 and 35.3 mg/mL, respectively. Collectively our results support the use of cellulose acetate membrane to obtain an ultra-filtered juice with significant health potential.
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Boman, B., M. Ek, W. Heyman et B. Frostell. « Membrane Filtration Combined with Biological Treatment for Purification of Bleach Plant Effluents ». Water Science and Technology 24, no 3-4 (1 août 1991) : 219–28. http://dx.doi.org/10.2166/wst.1991.0478.
Texte intégralRésumé :
A bleach plant effluent from softwood kraft pulping was treated in the laboratory with a combination of ultrafiltration and different biological methods. The E-stage effluent was firstly membrane filtered using membranes with a nominal cut-off of 8,000 Dalton. In the filtration, a concentration factor of 15 was used at 55°C. The treatment resulted in 89% AOX removal and 87% COD removal. Calculated in relation to the actual flows of E-stage and (C+D)-stage effluent at the mill, this corresponded to AOX and COD removals of 20% and 41% respectively. Before the biological treatment, the permeate was mixed with (C+D)-stage effluent and treated in three parallel biological systems, an aerated lagoon with and without solids recycle, an airlift system with a mixed fungal flora and an anaerobic filter. For the lagoon treatment, a hydraulic retention time of 7 days was used at biomass concentrations of 70, 350 and 480 mg TSS/l and 20-22°C. The fungal system was evaluated at retention times of 5.5 11 and 22 h, 770 mg TSS/l and 37°C. For the anaerobic filter, retention times of 1, 5 and 25 h at a temperature of 35°C were used. Very promising results were obtained with the combination of physical and biological treatment. The aerated lagoon with solids recycle gave the best results with 66% of AOX, 72% of COD and 95% of the BOD being removed in the combined process. The anaerobic filter also gave good results, but in practice a small aerobic post-treatment would probably be necessary. The three systems were also evaluated for the removal of chlorinated phenolic compounds and acute toxicity according to the Microtox test. The results suggest that a combination of membrane filtration and anaerobic/aerobic or just aerobic treatment would be an attractive way to handle kraft mill bleach plant effluents.
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Worku, Limenew Abate, Archana Bachheti, Rakesh Kumar Bachheti, Cristiano E. Rodrigues Reis et Anuj Kumar Chandel. « Agricultural Residues as Raw Materials for Pulp and Paper Production : Overview and Applications on Membrane Fabrication ». Membranes 13, no 2 (14 février 2023) : 228. http://dx.doi.org/10.3390/membranes13020228.
Texte intégralRésumé :
The need for pulp and paper has risen significantly due to exponential population growth, industrialization, and urbanization. Most paper manufacturing industries use wood fibers to meet pulp and paper requirements. The shortage of fibrous wood resources and increased deforestation are linked to the excessive dependence on wood for pulp and paper production. Therefore, non-wood substitutes, including corn stalks, sugarcane bagasse, wheat, and rice straw, cotton stalks, and others, may greatly alleviate the shortage of raw materials used to make pulp and paper. Non-woody raw materials can be pulped easily using soda/soda-AQ (anthraquinone), organosolv, and bio-pulping. The use of agricultural residues can also play a pivotal role in the development of polymeric membranes separating different molecular weight cut-off molecules from a variety of feedstocks in industries. These membranes range in applications from water purification to medicinal uses. Considering that some farmers still burn agricultural residues on the fields, resulting in significant air pollution and health issues, the use of agricultural residues in paper manufacturing can eventually help these producers to get better financial outcomes from the grown crop. This paper reviews the current trends in the technological pitch of pulp and paper production from agricultural residues using different pulping methods, with an insight into the application of membranes developed from lignocellulosic materials.
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Zhang, Yijun, Yuang Li, Xiaofeng Luan, Xin Li, Jiahong Jiang, Yuanyuan Fan, Mingxiao Li, Chengjun Huang, Lingqian Zhang et Yang Zhao. « A 3D Capillary-Driven Multi-Micropore Membrane-Based Trigger Valve for Multi-Step Biochemical Reaction ». Biosensors 13, no 1 (26 décembre 2022) : 26. http://dx.doi.org/10.3390/bios13010026.
Texte intégralRésumé :
Point-of-care testing (POCT) techniques based on microfluidic devices enabled rapid and accurate tests on-site, playing an increasingly important role in public health. As the critical component of capillary-driven microfluidic devices for POCT use, the capillary microfluidic valve could schedule multi-step biochemical operations, potentially being used for broader complex POCT tasks. However, owing to the reciprocal relationship between the capillary force and aperture in single-pore microchannels, it was challenging to achieve a high gating threshold and high operable liquid volume simultaneously with existing 2D capillary trigger valves. This paper proposed a 3D capillary-driven multi-microporous membrane-based trigger valve to address the issue. Taking advantage of the high gating threshold determined by micropores and the self-driven capillary channel, a 3D trigger valve composed of a microporous membrane for valving and a wedge-shaped capillary channel for flow pumping was implemented. Utilizing the capillary pinning effect of the multi-micropore membrane, the liquid above the membrane could be triggered by putting the drainage agent into the wedge-shaped capillary channel to wet the underside of the membrane, and it could also be cut off by taking away the agent. After theoretical analysis and performance characterizations, the 3D trigger valve performed a high gating threshold (above 1000 Pa) and high trigger efficiency with an operable liquid volume above 150 μL and a trigger-to-drain time below 6 s. Furthermore, the retention and trigger states of the valve could be switched for repeatable triggering for three cycles within 5 min. Finally, the microbead-based immunoreaction and live cell staining applications verified the valve’s ability to perform multi-step operations. The above results showed that the proposed 3D trigger valve could be expected to play a part in wide-ranging POCT application scenarios.
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D’Arena, Giovanni, Candida Vitale, Marta Coscia, Daniela Lamorte, Giuseppe Pietrantuono, Francesca Perutelli, Fiorella D’Auria et al. « CD200 Baseline Serum Levels Predict Prognosis of Chronic Lymphocytic Leukemia ». Cancers 13, no 16 (23 août 2021) : 4239. http://dx.doi.org/10.3390/cancers13164239.
Texte intégralRésumé :
Membrane-bound CD200 is overexpressed in chronic lymphocytic leukemia (CLL), and there is some evidence that its soluble ectodomain (sCD200) could also be involved in the pathophysiology and the disease. However, very little is known about sCD200’s prognostic significance. sCD200 was tested at diagnosis in 272 patients with CLL and in 78 age- and sex-matched healthy subjects using a specific human CD200 (OX-2 membrane glycoprotein) ELISA kit. A significantly higher concentration of sCD200 was found in CLL patients compared to controls. In our cohort, sCD200 was significantly higher in patients who were older than 66 years, with Binet stage C, unmutated IgVH and unfavorable (del11q or del17p) FISH. Time-to-first treatment and overall survival were significantly shorter in patients with higher sCD200 concentration, using as a cut-off 1281 pg/mL, the median value for sCD200 concentration in the whole CLL cohort. However, the prognostic impact of sCD200 was not confirmed in multivariate analysis. Baseline sCD200 values appeared to have an impact on the response to chemotherapy or chemo-immunotherapy, but not to targeted agents. Collectively, our data show that sCD200 serum levels correlate with more aggressive clinical and biological features and are able to predict a worse prognosis. This work supports the relevant role of CD200 not only as a diagnostic tool but also as a prognostic indicator and a potential therapeutic target in CLL.
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Loewe, Daniel, Hauke Dieken, Tanja A. Grein, Denise Salzig et Peter Czermak. « A Combined Ultrafiltration/Diafiltration Process for the Purification of Oncolytic Measles Virus ». Membranes 12, no 2 (18 janvier 2022) : 105. http://dx.doi.org/10.3390/membranes12020105.
Texte intégralRésumé :
Measles virus (MV) is an important representative of a new class of cancer therapeutics known as oncolytic viruses. However, process intensification for the downstream purification of this fragile product is challenging. We previously found that a mid-range molecular weight cut-off (300 kDa) is optimal for the concentration of MV. Here, we tested continuous and discontinuous diafiltration for the purification of MV prepared in two different media to determine the influence of high and low protein loads. We found that a concentration step before diafiltration improved process economy and MV yield when using either serum-containing or serum-free medium. We also found that discontinuous diafiltration conferred a slight benefit in terms of the permeate flow, reflecting the repetitive dilution steps and the ability to break down parts of the fouling layer on the membrane. In summary, the combined ultrafiltration/diafiltration process is suitable for the purification of MV, resulting in the recovery of ~50% infectious virus particles with a total concentration factor of 8 when using 5 diavolumes of buffer.
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Taiwo Ayodele, Aderinola, Alashi Adeola Monisola, Nwachukwu Ifeanyi Daniel, Fagbemi Tayo Nathaniel, Enujiugha Victor Ndigwe et Aluko Rotimi Emmanuel. « Antihypertensive and Antioxidant Properties of Moringa Oleifera Seed Enzymatic Protein Hydrolysate and Ultrafiltration Fractions ». Current Topics in Nutraceutical Research 17, no 4 (16 février 2019) : 437–44. http://dx.doi.org/10.37290/ctnr2641-452x.17:437-444.
Texte intégralRésumé :
The aim of this study was to evaluate the in vitro antioxidant and antihypertensive as well as potential cardioprotective properties of peptides generated from enzymatic hydrolysis of Moringa oleifera seed. Moringa protein isolate was digested with alcalase and the hydrolysate fractionated by ultrafiltration using 1, 3, 5, and 10 kDa molecular weight cut-off membranes. Results showed that membrane separation led to decreased free radical (DPPH, hydroxyl) scavenging but enhanced ferric reducing antioxidant power and metal ion chelation properties. The 1–3 kDa peptide fraction was the most active against angiotensin converting enzyme and renin with 6.70% and 24.62% increases, respectively when compared to the hydrolysate. Oral administration (200 mg/kg body weight) to spontaneously hypertensive rats (SHR) resulted in significant decreases in systolic (SBP), diastolic and mean arterial (MAP) blood pressure for the hydrolysates and peptide fractions when compared to the negative control. The 1–3 kDa peptide fraction also showed the greatest (–35 mm Hg) in SBP along with fastest (2 h) reduction of SBP and MAP in the SHR. The hydrolysate produced the most persistent SBP reduction with up to –34 mm Hg after 24 h. However, the longer peptides (>10 kDa) were the most effective (–78 beats per min) in reducing SHR heart rate. The results suggest that the alcalase-hydrolyzed M. oleifera seed peptides could function as potential ingredients for the formulations of functional foods and nutraceuticals with antihypertensive benefits.
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Baptista, Sílvia, Cristiana A. V. Torres, Chantal Sevrin, Christian Grandfils, Maria A. M. Reis et Filomena Freitas. « Extraction of the Bacterial Extracellular Polysaccharide FucoPol by Membrane-Based Methods : Efficiency and Impact on Biopolymer Properties ». Polymers 14, no 3 (19 janvier 2022) : 390. http://dx.doi.org/10.3390/polym14030390.
Texte intégralRésumé :
In this study, membrane-based methods were evaluated for the recovery of FucoPol, the fucose-rich exopolysaccharide (EPS) secreted by the bacterium Enterobacter A47, aiming at reducing the total water consumption and extraction time, while keeping a high product recovery, thus making the downstream procedure more sustainable and cost-effective. The optimized method involved ultrafiltration of the cell-free supernatant using a 30 kDa molecular weight cut-off (MWCO) membrane that allowed for a 37% reduction of the total water consumption and a 55% reduction of the extraction time, compared to the previously used method (diafiltration-ultrafiltration with a 100 kDa MWCO membrane). This change in the downstream procedure improved the product’s recovery (around 10% increase) and its purity, evidenced by the lower protein (8.2 wt%) and inorganic salts (4.0 wt%) contents of the samples (compared to 9.3 and 8.6 wt%, respectively, for the previously used method), without impacting FucoPol’s sugar and acyl groups composition, molecular mass distribution or thermal degradation profile. The biopolymer’s emulsion-forming and stabilizing capacity was also not affected (emulsification activity (EA) with olive oil, at a 2:3 ratio, of 98 ± 0% for all samples), while the rheological properties were improved (the zero-shear viscosity increased from 8.89 ± 0.62 Pa·s to 17.40 ± 0.04 Pa·s), which can be assigned to the higher purity degree of the extracted samples. These findings demonstrate a significant improvement in the downstream procedure raising FucoPol’s recovery, while reducing water consumption and operation time, key criteria in terms of process economic and environmental sustainability. Moreover, those changes improved the biopolymer’s rheological properties, known to significantly impact FucoPol’s utilization in cosmetic, pharmaceutical or food products.