An evaluation of ozone dry deposition in global scale chemistry climate models

Dry deposition to the Earth's surface is an important process from both an atmospheric and biospheric perspective. Dry deposition controls the atmospheric abundance of many compounds as well as their input to vegetative surfaces, thus linking the atmosphere and biosphere. In many atmospheric and Earth system models it is represented using "resistance in series" schemes developed in the 1980s. These methods have remained relatively unchanged since their development and do not take into account more recent understanding of the underlying processes that have been gained through field and laboratory based studies. In this study we compare dry deposition of ozone across 15 models which contributed to the TF HTAP model intercomparison to identify where differences occur. We compare modelled dry deposition of ozone to measurements made at a variety of locations in Europe and North America, noting differences of up to a factor of two but no clear systematic bias over the sites examined. We identify a number of measures that are needed to provide a more critical evaluation of dry deposition fluxes and advance model development

H2 production by the photocatalytic reforming of cellulose and raw biomass using Ni, Pd, Pt and Au on titania

Here, we report a method for sustainable hydrogen production using sunlight and biomass. It is shown that cellulose can be photoreformed to produce hydrogen, even in solid form, by use of metal-loaded titania photocatalysts. The experiments performed verified that the process is enabled by initial hydrolysis via glucose, which itself is shown to be efficiently converted to produce hydrogen by photocatalysis. Importantly, it is shown that not only precious metals such as Pt, Pd and Au can be used as the metal component, but also much more economic and less environmentally damaging Ni is effective. Even more importantly, we show for the first time, to the best our knowledge, that fescue grass as raw biomass can be effective for hydrogen production without significant pretreatment. This provides additional benefits for the efficiency of biomass hydrogen production, because fewer processing steps for the raw material are required than in the production of purer forms of cellulose, for example

Low-field 2D NMR relaxation and DRIFTS studies of glucose isomerization in zeolite Y: New insights into adsorption effects on catalytic performance

Sn and Ga doped zeolite Y catalysts were tested for the isomerization of glucose to fructose carried out in different solvents (water, methanol and ethanol). Therein, ethanol favoured a Lewis acid site catalyzed pathway that promotes glucose isomerization to fructose, whereas methanol resulted in an equal distribution of products (mannose, fructose and alkyl fructoside). In contrast, the catalysts were totally inactive in water solvent. NMR relaxation measurements, including solvent displacement experiments, suggested that the lack of catalytic activity in water is due to the strong adsorption of this solvent within the zeolite pores blocking reactants from the Lewis acid sites active for the sugar isomerization. In comparison, ethanol adsorbs relatively more strongly than methanol, hence is retained in the pores where solvated fructose is preferentially prevented from the further reaction on Bronsted acid sites situated outside of the pore space. NMR relaxation measurements using pyridine and tetrahydrofuran (THF) and pyridine-DRIFTS measurements suggest metal doping had little effect on the overall relative acid strength of the zeolites but resulted in zeolites with increased Lewis acid strength relative to the non-doped zeolites. The results reported provide direct experimental evidence on the importance of adsorption properties of solvents within zeolites used for glucose to fructose isomerization and may serve as a starting point for a new approach towards designing and optimizing such catalytic systems. & COPY; 2023 The Author(s). Published by Elsevier Inc. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/)

Contrasting the EXAFS obtained under air and H-2 environments to reveal details of the surface structure of Pt-Sn nanoparticles

Understanding the surface structure of bimetallic nanoparticles is crucial for heterogeneous catalysis. Although surface contraction has been established in monometallic systems, less is known for bimetallic systems, especially of nanoparticles. In this work, the bond length contraction on the surface of bimetallic nanoparticles is revealed by XAS in H2 at room temperature on dealloyed Pt–Sn nanoparticles, where most Sn atoms were oxidized and segregated to the surface when measured in air. The average Sn–Pt bond length is found to be ∼0.09 Å shorter than observed in the bulk. To ascertain the effect of the Sn location on the decrease of the average bond length, Pt–Sn samples with lower surface-to-bulk Sn ratios than the dealloyed Pt–Sn were studied. The structural information specifically from the surface was extracted from the averaged XAS results using an improved fitting model combining the data measured in H2 and in air. Two samples prepared so as to ensure the absence of Sn in the bulk were also studied in the same fashion. The bond length of surface Sn–Pt and the corresponding coordination number obtained in this study show a nearly linear correlation, the origin of which is discussed and attributed to the poor overlap between the Sn 5p orbitals and the available orbitals of the Pt surface atoms

Physical and Electrochemical Investigations into Blended Electrolytes Containing a Glyme Solvent and Two Bis{(trifluoromethyl)sulfonyl}imide-Based Ionic Liquids

International audienceIn this paper, we report on thermophysical and electrochemical investigations of a series of molecular solvent/ionic liquid (IL) binary mixture electrolytes. Tetraethylene glycol dimethyl ether (TEGDME) is utilized as the molecular solvent component in separate mixtures with two bis{(trifluoromethyl)sulfonyl}imide anion based ILs paired with similarly sized cyclic and acyclic alkylammonium cations; 1-butyl-1-methylpyrrolidinium bis{(trifluoromethyl)sulfonyl}imide, [Pyrr14][TFSI], or N-butyl-N,N-dimethyl-N-ethylammonium bis{(trifluoromethyl)sulfonyl}imide, [N1124][TFSI]. The blending of ILs with select molecular solvents is an important strategy for the improvement of the typically sluggish transport capabilities of these interesting electrolytic solvents. Bulk volumetric and transport properties are reported as a function of temperature and binary mixture formulation; demonstrating the capacity for enhancing desired properties of the IL. Micro-disk electrode voltammetry and chronoamperometry in O2-saturated binary mixture electrolytes was used to assess the effect of formulation on the solubility and diffusivity of the dissolved gas. In addition, further investigations of the behavior of the O2 redox couple at a GC macro-disk electrode are discussed

The addition of CO2 to four superbase ionic liquids: a DFT study

The addition of carbon dioxide to four superbase ionic liquids, [P3333][Benzim], [P3333][124Triz], [P3333][123Triz] and [P3333][Bentriz] was studied using a molecular DFT approach involving anions alone and individual ion pairs. Intermolecular bonding within the individual ion pairs is characterised by a number of weak hydrogen bonds, with the superbase anion geometrically arranged so as to maximize interactions between the heterocyclic N atoms and the cation. The pairing energies show no correlation to the observed CO2 adsorption capacity. Addition of CO2 to the anion alone clearly resulted in the formation of a covalently-bound carbamate function with the strength of binding correlated to experimental capacity. In the ion pair however the cation significantly alters the nature of the bonding such that the overall cohesive energy is reduced. Formation of a strong carbamate function occurs at the expense of weakening the interaction between anion and cation. In the more weakly absorbing ion pairs which contain [123Triz](-) and [Bentriz](-), the carbamate-functionalised systems are very close in energy to adducts in which CO2 is more weakly bound, suggesting an equilibrium between the chemi- and physisorbed CO2

Probing the dynamics and structure of confined benzene in MCM-41 based catalysts

A combination of Molecular Dynamics (MD) simulations and Quasielastic Neutron Scattering (QENS) experiments has been used to investigate the dynamics and structure of benzene in MCM-41 based catalysts. QENS experiments of benzene as both an unconfined liquid and confined in the catalyst Pt/MCM-41 find that the mobility of benzene decreases upon confinement as shown by the decreased diffusion coefficients. Complementary MD simulations on benzene in MCM-41 show agreement with the QENS experiments when using a novel fully flexible model of MCM-41. Structural information from the MD simulations show that benzene in MCM-41 has a significantly different structure from that of the bulk liquid; with benzene molecules closer together and no prefered orientation

Advancing Pressure Ulcer Prevention: Evaluating the Impact of Patient and Lay Carer Education

Decubitus ulcers, also known as bedsores or pressure ulcers, result from prolonged pressure on the skin, with contributing factors such as shear forces, friction, and excessive moisture. Pressure ulcers have significant physical, social, and psychological consequences for patients and impose a substantial financial burden on healthcare providers. Patient and caregiver education has been suggested as a potential approach for preventing pressure sores. In order to investigate the potential preventive impact, O'Connor et al. conducted a Cochrane systematic review. Their study aimed to assess the effectiveness of educational interventions for patients and caregivers in preventing pressure ulcers. This commentary aims to critically appraise the methods used within the Cochrane systematic review by O'Connor et al 2022 and expand upon the findings in the context of clinical practice