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Background and Aims Dialytic clearance of protein-bound toxins and large middle molecules is poor by diffusive treatment and limited by high-flux hemodialysis (HD) and on-line hemodiafiltration (OL-HDF), and only a few studies have examined how to improve their removal by other extracorporeal strategies. Since 2017, there is a new generation of polymethyl methacrylate (PMMA) membranes that suppress platelet adhesion on the membrane surface improving hemocompatibility and permeability, while also maintaining adsorption properties related to conventional PMMA membranes. Expanded HD (HDx) with medium cut-off (MCO) membranes has also recently been incorporated into clinical practice and may improve the removal of uremic toxins in HD treatments. The aim of this pilot study was to compare the efficacy of a new high-flux PMMA dialyzer (Filtryzer® NF-2.1H) in a post-dilution OL-HDF session with a new MCO membrane (Theranova® 400) in a HDx session. Method In an open, cross-over, single-center, controlled, prospective clinical study, 40 adult stable HD patients were assigned to be treated by post-dilution OL-HDF with the NF-2.1H dialyzer or by HDx with the Theranova 400 dialyzer. All other dialysis parameters, including blood and dialysate flow rates, length of dialysis session, and ultrafiltration rate remained unchanged during both sessions. P-cresyl sulfate (PCS), indoxyl sulfate (IS), and kappa (κ) and lambda( λ) free light chains (FLC) reduction rates were intraindividually compared for the two dialyzer types (primary outcomes). Secondary outcomes included the kt and the reduction ratio of blood urea nitrogen, phosphate and β2 -microglobulin (β 2-m). Results The reduction ratio of protein-bound toxins ranges from 60% to 67%, with no differences between membranes (Figure). PMMA membrane achieved greater FLC reduction ratios than MCO membrane, reaching significance for λFLC (56.6% vs. 77.4%; p < 0.001). Conversely, β2M reduction ratio was slightly but significantly higher with MCO membrane (68.5 vs. 72.1%; p = 0.002). Small molecules removal including urea and phosphate were similar in both groups, achieving an optimal Kt with no differences between groups (61.3±9.2 Vs. 59.7±9.3; p=0.16). Albumin reduction ratio tended to be higher with PMMA membrane without reaching significance (10.1±5.9% Vs. 7.8±12.3%; p=0.17). The mean convective volume achieved with PMMA was 23.5±4.4 L. Conclusion This study suggested that new high-flux PMMA dialyzer in post-dilution OL-HDF mode might achieve better FLC reduction ratios than MCO dyalizer in HDx mode, whereas both techniques may equally remove protein-bound toxins. OL-HDF with new PMMA membranes could be a good dialysis strategy for adding convective transport to the well-known mechanisms of diffusion and absorption previously described with conventional PMMA membranes, enabling an adequate substitution volume.

El presente trabajo reflexiona acerca de los retos que el sector editorial en España debe afrontar para adecuar su oferta a las nuevas necesidades y expectativas generadas por los lectores-usuarios en la actual era digital. Partiendo de un cambio en el concepto de textualidad propiciado por los nuevos soportes de lectura, se hace hincapié en las novedades que las ediciones críticas en formato digital deberán aportar para acercar los nuevos contenidos a un público especializado que demanda cada vez más una mayor interacción con el texto y los soportes de lectura. Asimismo, se destaca la importancia de aunar esfuerzos entre los profesionales en el ámbito de la edición textual, la filología y la informática para llegar a un consenso que ponga fin al “caos” reinante en el mundo de la edición crítica digital. El presente trabajo reflexiona acerca de los retos que el sector editorial en España debe afrontar para adecuar su oferta a las nuevas necesidades y expectativas generadas por los lectores-usuarios en la actual era digital. Partiendo de un cambio en el concepto de textualidad propiciado por los nuevos soportes de lectura, se hace hincapié en las novedades que las ediciones críticas en formato digital deberán aportar para acercar los nuevos contenidos a un público especializado que demanda cada vez más una mayor interacción con el texto y los soportes de lectura. Asimismo, se destaca la importancia de aunar esfuerzos entre los profesionales en el ámbito de la edición textual, la filología y la informática para llegar a un consenso que ponga fin al “caos” reinante en el mundo de la edición crítica digital.

The title reaction has been theoretically studied by using MP2, QCISD, QCISD(T), CCSD(T), CASSCF, and CASPT2 methods with various basis sets. At single-reference MP2 and QCISD levels of theory, the potential energy hypersurface (HPES) shows a two-step reaction mechanism through two transition states (TS1 and TS2) and an intermediate (Int). However, the multiconfigurational CASSCF HPES shows a one-step reaction mechanism, as was previously found for the NH2 + O3 and OH + O3 reactions. The results show that the reactivity of the isoelectronic series of NH2, OH, and F radicals increases from the amino radical to the fluorine atom.

The initial step of the mechanism of the OH + β-pinene gas-phase reaction was investigated by means of ab initio calculations. Four different possibilities for the OH addition to the double bond are discussed, corresponding to the addition on each C atom of the double bond, and for each one, either the syn or anti OH attack to the two methyl groups on the (bi)cyclic molecule. Energy barriers calculated at the QCISD(T)/6-31G(d) level of theory on UMP2/6-31G(d) optimised structures, show that there are preferred orientations for the OH addition under atmospheric conditions of temperature and pressure.

The deviation of the NH2 pseudo-first-order decay Arrhenius plots of the NH2 + O3 reaction at high ozone pressures measured by experimentalists, has been attributed to the regeneration of NH2 radicals due to the subsequent reactions of the products of this reaction with ozone. Although these products have not yet been characterized experimentally, the radical H2NO has been postulated, because it can regenerate NH2 radicals through the reactions: H2NO + O3 NH2 + O2 and H2NO + O3 HNO + OH + O2. With the purpose of providing a reasonable explanation from a theoretical point of view to the kinetic observed behaviour of the NH2 + O3 system, we have carried ab initio electronic structure calculations on both H2NO + O3 possible reactions. The results obtained in this article, however, predict that of both reactions proposed, only the H2NO + O3 NH2 + O2 reaction would regenerate indeed NH2 radicals, explaining thus the deviation of the NH2 pseudo-first-order decay observed experimentally. © 2003 Wiley Periodicals, Inc. J Comput Chem 24: 1321–1328, 2003

The atmospheric reaction NH 2 +0 3 →H 2 NO+O 2 has been investigated theoretically by using MP2, QCISD, QCISD(T), CCSD(T), CASSCF, and CASPT2 methods with various basis sets. At the MP2 level or theory, the hypersurface of the potential energy (HPES) shows a two step reaction mechanism. Therefore, the mechanism proceeds along two transition states (TS1 and TS2), seperated by an intermediate disignated as Int. However, when the single-reference higler correlated QCISD and the multiconfigurational CASSCF methodologies have been employed, the minimum structure Int and TS2 are not found on the HPES, which thus confirms a direct reaction mechanism. Single-reference high correlated and multiconfigurational methods consistently predict the barrier height of the reaction to be within the range of 3.9 to 6.6 kcal mol -1 , wich is somewhat higher than the experiemntal value. The calculated reaction enthalpy is - 67.7 kcal mol -1 .

The gas-phase reaction HCO+O 2 →CO+HO 2 has been investigated by means of ab initio calculations. The mechanism can proceed through either a direct hydrogen abstraction or addition of O 2 to the formyl radical. The energy barriers calculated at the QCISD(T)/6-311G(2df,2p) level of theory upon QCISD/6-311G(d,p) optimized structures are, respectively, of 2.98 kcal mol −1 for the direct abstraction and of 2.26 kcal mol −1 for the addition. Thus, the results obtained show that there is not a dominant pathway in the HCO+O 2 reaction under atmospheric conditions of temperature and pressure.

The atmospheric reaction between NO and ozone has been investigated using ab initio methods. The structures of all reactants, products, intermediates, and transition states of reaction 1 have been optimized and characterized at the UMP2(full) level of theory. The 6-31G(d), 6-311G(d), and 6-311G(df) basis sets have also been used to calibrate the effect of the basis set functions on the optimized structures and energies of all stationary points. Finally, we have reoptimized at the UMP4(SDQ, full)/6-31G(d) and 6-311G(d) levels. The energetics of the reaction has been studied more accurately within the G2 and G2(MP2) schemes. Also, QCISD(T)/6-311G(d) single-point calculations have been performed by using UMP2(full)/6-31G(d), 6-311G(d), and 6-311G(df) geometries. The mechanism study of the NO + O3 → NO2 + O2 reaction has shown that the transition between reactants and products is not direct, but it proceeds along two transition states (TS1 and TS2) separated by the intermediate (A). There is also the possibil...

The atmospheric reaction (1) OH + O 3 → + O 2 was investigated theoretically by using MP2, QCISD, QCISD(T), and CCSD(T) methods with various basis sets. At the highest level of theory, namely, QCISD, the reaction is direct, with only one transition state between reactants and products. However, at the MP2 level, the reaction proceeds through a two-step mechanism and shows two transition states, TS1 and TS2, separated by an intermediate, Int. The different methodologies employed in this paper consistently predict the barrier height of reaction (1) to be within the range 2.16 - 5.11 kcal mol -1 , somewhat higher than the experimental value of 2.0 kcal mol -1 .