Do Membranes Dream of Electric Tubes? Advanced Membranes Using Carbon Nanotube-Polymer Nanocomposites

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Demandes de congés de MM. Lannoy et Pernel, lors de la séance du 2 aout 1790

Lannoy Charles-François, comte de, Pernel Antoine-François. Demandes de congés de MM. Lannoy et Pernel, lors de la séance du 2 aout 1790. In: Archives Parlementaires de 1787 à 1860 - Première série (1787-1799) Tome XVII - Du 9 juillet au 12 aout 1790. Paris : Librairie Administrative P. Dupont, 1884. p. 497

Production of Stable Electrically Conductive PVDF Membranes Based on Polydopamine-Polyethyleneimine—Assisted Deposition of Carbon Nanotubes

Electrically conductive membranes (ECMs) have emerged as a multifunctional separation technology that integrates membrane filtration with electrochemical reactions. Physical stability remains a critical challenge for ECMs synthesized by coating polymer membranes with conductive materials. In this article, polydopamine (PDA) and polyethyleneimine (PEI) were used to facilitate the synthesis of significantly more stable ECMs using poly(vinylidene fluoride) (PVDF) ultrafiltration membranes and carbon nanotubes (CNTs). Four different synthesis methods were compared in terms of the final surface stability and separation properties: (1) CNTs deposited on PEI-crosslinked PDA-coated PVDF membranes, (2) PEI-crosslinked CNTs deposited on PDA-coated PVDF, (3) PDA, PEI and CNTs sequentially deposited layer-by-layer on PVDF, and (4) PEI-crosslinked PDA deposited on CNT-coated PVDF. The results revealed that method 1 generated ECMs with the greatest physical stability, highest electrical conductivity (18,518 S/m), and sufficient permeability (395.2 L/(m2·h·bar). In comparison, method 2 resulted in membranes with the highest permeability (2128.5 L/(m2·h·bar), but with low surface conductivity (502 S/m) and poor physical stability (i.e., 53–75% lower peel-off forces compared to other methods). Overall, methods 1, 3, and 4 can be used to make highly conductive membranes with a 97–99% removal of methyl orange by electrochemical degradation at −3 V

Demandes de congés de MM. Lannoy et Pernel, lors de la séance du 2 aout 1790

Lannoy Charles François, comte de, Pernel Antoine François. Demandes de congés de MM. Lannoy et Pernel, lors de la séance du 2 aout 1790. In: Archives Parlementaires de 1787 à 1860 - Première série (1787-1799) Tome XVII - Du 9 juillet au 12 aout 1790. Paris : Librairie Administrative P. Dupont, 1884. p. 497

Low-cost automated flat-sheet membrane casting: An open-source, advanced manufacturing approach

Novel membrane materials developed in research labs struggle to gain widespread industrial adoption due in part to insufficient reproducibility and unreliable performance data. Open-source hardware approaches, especially 3D printing, enable the democratization of automation within a laboratory setting, and in the context of membranes, can minimize the inherent variability associated with manual methods of membrane casting. In this study, the native hardware and firmware of an inexpensive, conventional 3D printer was extensively modified for the purpose of flat-sheet membrane casting. Replicate poly (ether-ether ketone) (PEEK) membranes were cast with a thickness coefficient of variation of ∼10 % using the modified device. Cast membranes were used to assess the importance of controlling shear rate by characterizing both intra- and inter-film variability. Statistical differences in pure water permeability were observed across tested shear rates, with distinct morphological changes occurring to the membrane substructure. Overall, the technology developed in this study is shown to be an extremely useful approach for improving the process of developing membranes at the bench-scale

Ni-Cu bimetallic catalytic membranes for continuous nitrophenol conversion

International audienceBimetallic nanocatalysts are of great interest due to their greater activity, selectivity, and chemical and electrochemical stability, compared to their monometallic counterparts. Bimetallic nanocatalysts formed from abundant and inexpensive elements provide greater opportunities for applications over noble metal catalysts. In this study, inexpensive Ni-Cu bimetallic catalytic membrane microreactors (CMMRs) were synthesized in a simple two-step process to catalytically degrade the environmental pollutant, 4-nitrophenol (4-NP), and produce the valuable feedstock, 4-aminophenol (4-AP). Ni-Cu nanoparticles were either produced by a replacement reduction reaction or a co-reduction reaction, producing either bimodal or integrated nanostructures, respectively, as demonstrated by transmission electron microscopy (TEM), while the electronic reconfiguration between bimetallic systems was verified by X-ray photoelectron spectroscopy (XPS). Compared to 4-NP batch conversion, flow-through reactions demonstrated enhanced mass transfer contributing to 2-fold higher conversion (>99%), 30-fold higher processing capacity (0.95 mol∙m−2∙h−1) and co-reduced Ni-Cu CMMRs boasted a reaction rate constant of 725.03 min−1.4-NP conversion on the Ni-Cu catalysts in the presence of NaBH4 followed the Langmuir-Hinshelwood (L-H) mechanism, and the conversion efficiency was highly dependent on flow rate, representing an optimization trade-off critical for CMMR applications. The polydopamine-assisted fabrication and the tortuous membrane pore structure contributed to the CMMRs’ stability with <5% metal loss during operation. The enhanced activity was attributed to the synergistic electronic effects of the Ni-Cu bimetallic structure, the metal-polydopamine interactions, and the catalysts’ unique structure and high surface area

Comprehensive examination of mesophases formed by DMPC and DHPC mixtures

Mixtures of long- and short-chain phospholipids, specifically 14:0 and 6:0 phosphatidylcholines (DMPC and DHPC), have been used successfully in NMR studies as magnetically alignable substrates for membrane-associated proteins. However, recent publications have shown that the phase behavior of these mixtures is much more complex than originally thought. Using polarized light microscopy and small-angle neutron scattering, phase diagrams of DMPC/DHPC mixtures at molar ratios of 2, 3.2, and 5 have been determined. Generally, at temperatures below the main-chain melting transition of DMPC (T<SUB>M</SUB> = 23&#176;C), an isotropic phase of disklike micelles is found. At high temperatures (T &gt; 50&#176;C), a lamellar phase consisting of either multilamellar vesicles (MLV) or extended lamellae is formed, which at low lipid concentrations (e.g., MLV) coexists with an excess of water. At intermediate temperatures and lipid concentrations, a chiral nematic phase made up of wormlike micelles was observed

Influencia de la relaciones familiares en el rendimiento Escolar

El presente trabajo está dirigido a brindar pautas con la única finalidad de mejorar la comunicación e interrelación entre padres de familia, estudiantes y docentes para de esta manera fortalecer el respeto, el amor, la solidaridad y cooperación entre todos los que integran la comunidad educativa. Al estar estructurada la familia en una continua comunicación es la mejor manera para mantener unida a la familia y así poder vencer las dificultades que en el diario vivir deben afrontar con madurez tanto los padres como los hijos para no hacer daño a ninguna de las partes, que son fundamentales para el desarrollo de la sociedad, de la familia y de sí mismo, en la cual las instituciones educativas son las fortalecedoras de los valores inculcados por los padres de familia en el seno del hogar. El ser humano necesita cultivar más la parte afectiva y emocional para poder estar en condiciones de desenvolverse mejor en la vida diaria, solamente así podrán los jóvenes sentirse seguros y protegidos aunque su padre o madre no se encuentre a su lado cuando lo necesite, sabiendo que pueden contar con profesionales dentro de la institución que le brinde su apoyo y su confianza cuando sus estudiantes más lo necesiten, siendo la comunidad educativa una sola familia y sus miembros estén en continua interacción e interrelación. Cabe recalcar que la propuesta mencionada en eta tesis no tiene ningún inconveniente en ser realizada ya que participaran activamente padres de familia, profesores y estudiantes ya que toda la tesis se realizó a un análisis de los problemas que afectan directa e indirectamente a los alumnos en su normal desenvolvimiento dentro de la institución y rendimiento escolar