Effect of salinity stress on antioxidant activity and grain yield of different wheat genotypes

In order to evaluate the antioxidant activity of wheat in salinity stress conditions, an experiment with 27 wheat genotypes grown on two types of soil was conducted: solonetz (increased salinity) and chernozem (control), during two vegetation seasons (2015/2016 and 2016/2017). Analysis of DPPH radical scavenging activity and phenolic content (PC) were performed in different phenophases of wheat (tillering, stem elongation and heading). Genotypes showed significantly higher DPPH radical scavenging activity (9.82 mg trolox equivalents (TE) per mg of dry matter (d.m.)) and PC (8.15 mg gallic acid equivalents (GAE) per mg d.m.) under salinity stress conditions compared to values obtained on control (8.52 mg TE mg-1 d.m. and 7.13 mg GAE mg-1 d.m., respectively). All analyzed factors (genotype, soil type and year) had the highly significant influence on phenotypic variation of grain yield. Salinity stress reduced grain yield by 30%, whereas drought stress in 2016/2017 vegetation season reduced grain yield by 20%. Highly significant and positive correlations are present between grain yield and parameters of antioxidant activity in all growth stages of wheat and both soil conditions. Therefore, it could be possible to select salinity tolerant genotypes in early growth stages. DPPH scavenging activity and total phenolic content are in highly significant and positive correlation in all growth stages, which indicates that antioxidant activity is highly derived by phenolics

Multiscale Mechanistic Insights of Shaped Catalyst Body Formulations and Their Impact on Catalytic Properties

International audienceZeolite-based catalysts are globally employed in many industrial processes, such as in crude-oil refining and in the production of bulk chemicals. However, to be implemented in industrial reactors efficiently, zeolite powders are required to be shaped in catalyst bodies. Scale-up of zeolite catalysts into such forms comes with side effects to its overall physicochem-ical properties and to those of its constituting components. Although fundamental research into "technical" solid catalysts is scarce, binder effects have been reported to significantly impact their catalytic properties and lifetime. Given the large number of additional (in)organic components added in the formulation, it is somehow surprising to see that there is a distinct lack of research into the unintentional impact organic additives can have on the properties of the zeolite and the catalyst bodies in general. Here, we systematically prepared a series of alumina-bound zeolite ZSM-5-based catalyst bodies, with organic additives such as peptizing, plasticizing, and lubricating agents, to rationalize their impacts on the physicochemical properties of the shaped catalyst bodies. By utilizing a carefully selected arsenal of bulk and high-spatial resolution multiscale characterization techniques, as well as specifically sized bioinspired fluorescent nanoprobes to study pore accessibility, we clearly show that, although the organic additives achieve their primary function of a mechanically robust material, uncontrolled processes are taking place in parallel. We reveal that the extrusion process can lead to zeolite dealumination (from acid peptizing treatment, and localized steaming upon calcination); meso-and macropore structural rearrangement (via burning-out of organic plasticizing and lubricating agents upon calcination); and abating of known alumina binder effects (via scavenging of Al species via chelating lubricating agents), which significantly impact catalytic performance. Understanding the mechanisms behind such effects in industrial-grade catalyst formulations can lead to enhanced design of these important materials, which can improve process efficiency in a vast range of industrial catalytic reactions

Effect of salinity stress on antioxidant activity and grain yield of different wheat genotypes

In order to evaluate the antioxidant activity of wheat in salinity stress conditions, an experiment with 27 wheat genotypes grown on two types of soil was conducted: solonetz (increased salinity) and chernozem (control), during two vegetation seasons (2015/2016 and 2016/2017). Analysis of DPPH radical scavenging activity and phenolic content (PC) were performed in different phenophases of wheat (tillering, stem elongation and heading). Genotypes showed significantly higher DPPH radical scavenging activity (9.82 mg trolox equivalents (TE) per mg of dry matter (d.m.)) and PC (8.15 mg gallic acid equivalents (GAE) per mg d.m.) under salinity stress conditions compared to values obtained on control (8.52 mg TE mg-1 d.m. and 7.13 mg GAE mg-1 d.m., respectively). All analyzed factors (genotype, soil type and year) had the highly significant influence on phenotypic variation of grain yield. Salinity stress reduced grain yield by 30%, whereas drought stress in 2016/2017 vegetation season reduced grain yield by 20%. Highly significant and positive correlations are present between grain yield and parameters of antioxidant activity in all growth stages of wheat and both soil conditions. Therefore, it could be possible to select salinity tolerant genotypes in early growth stages. DPPH scavenging activity and total phenolic content are in highly significant and positive correlation in all growth stages, which indicates that antioxidant activity is highly derived by phenolics

Assessment of oxide nanoparticle stability in liquid phase transmission electron microscopy

Studying liquid phase nanoscale dynamic processes of oxide nanoparticles is of considerable interest to a wide variety of fields. Recently developed liquid phase transmission electron microscopy (LP-TEM) is a promising technique, but destabilization of oxides by solid-liquid-electron interactions remains an important challenge. In this work we present a methodology to assess LP-TEM oxide stability in an aqueous phase, by subjecting several oxides of technological importance to a controlled electron dose in water. We show a correlation based on the Gibbs free energy of oxide hydration that can be used to assess the stability of oxides and demonstrate the existence of several remarkably stable oxides, with no observable structural changes after one hour of electron beam irradiation in LP-TEM. Rationalizing such destabilization phenomena combined with the identification of stable oxides allows for designing LP-TEM experiments free from adverse beam effects and thus investigations of numerous relevant nanoscale processes in water

Erratum to: Assessment of oxide nanoparticle stability in liquid phase transmission electron microscopy

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Assessment of oxide nanoparticle stability in liquid phase transmission electron microscopy

Studying liquid phase nanoscale dynamic processes of oxide nanoparticles is of considerable interest to a wide variety of fields. Recently developed liquid phase transmission electron microscopy (LP-TEM) is a promising technique, but destabilization of oxides by solid-liquid-electron interactions remains an important challenge. In this work we present a methodology to assess LP-TEM oxide stability in an aqueous phase, by subjecting several oxides of technological importance to a controlled electron dose in water. We show a correlation based on the Gibbs free energy of oxide hydration that can be used to assess the stability of oxides and demonstrate the existence of several remarkably stable oxides, with no observable structural changes after one hour of electron beam irradiation in LP-TEM. Rationalizing such destabilization phenomena combined with the identification of stable oxides allows for designing LP-TEM experiments free from adverse beam effects and thus investigations of numerous relevant nanoscale processes in water

Nanoscale intimacy in bifunctional catalysts for selective conversion of hydrocarbons

The ability to control nanoscale features precisely is increasingly being exploited to develop and improve monofunctional catalysts(1-4). Striking effects might also be expected in the case of bifunctional catalysts, which are important in the hydrocracking of fossil and renewable hydrocarbon sources to provide high-quality diesel fuel(5-7). Such bifunctional hydrocracking catalysts contain metal sites and acid sites, and for more than 50 years the so-called intimacy criterion(8) has dictated the maximum distance between the two types of site, beyond which catalytic activity decreases. A lack of synthesis and material-characterization methods with nanometre precision has long prevented in-depth exploration of the intimacy criterion, which has often been interpreted simply as 'the closer the better' for positioning metal and acid sites(8-11). Here we show for a bifunctional catalyst-comprising an intimate mixture of zeolite Y and alumina binder, and with platinum metal controllably deposited on either the zeolite or the binder-that closest proximity between metal and zeolite acid sites can be detrimental. Specifically, the selectivity when cracking large hydrocarbon feedstock molecules for high-quality diesel production is optimized with the catalyst that contains platinum on the binder, that is, with a nanoscale rather than closest intimacy of the metal and acid sites. Thus, cracking of the large and complex hydrocarbon molecules that are typically derived from alternative sources, such as gas-to-liquid technology, vegetable oil or algal oil(6,7), should benefit especially from bifunctional catalysts that avoid locating platinum on the zeolite (the traditionally assumed optimal location). More generally, we anticipate that the ability demonstrated here to spatially organize different active sites at the nanoscale will benefit the further development and optimization of the emerging generation of multifunctional catalysts(12-15)