Effects of interaction with sulphur compounds and free volume in imidazolium-based ionic liquid on desulphurisation: a molecular dynamics study

Interaction energy with sulphur compounds and free volume in imidazolium-based ionic liquid were calculated by molecular dynamics (MD) simulations to examine their effects on desulphurisation. From microstructure analysis and energy contribution calculation, it is found that an increasing fractional free volume in ionic liquid and an enhancement of interaction with solute by tuning the structure of ionic liquid or oxidising sulphur compounds are favourable for desulphurisation, which allows more efficient packing of sulphur compounds in ionic liquids and more easily extraction of sulphur compounds from fuel. The MD results are in good agreement with experimental desulphurisation performance.     

Lipase‐catalyzed enantioselective transesterification of prochiral 1‐((1,3‐dihydroxypropan‐2‐yloxy)methyl)‐5,6,7,8‐tetrahydroquinazoline‐2,4(1H,3H)‐dione in ionic liquids

The application of ionic liquids as solvents for transesterification of prochiral pirymidine acyclonucleoside using lipase (EC 3.1.1.3) Amano PS from Burkholderia cepacia (BCL) is reported. The effect of using medium reaction, acyl group donor, and temperature on the activity and enantioselectivity of BCL was studied. From the investigated ionic solvents, the hydrophobic ionic liquid [BMIM]PF₆] was the preferred medium for enzymatic reactions. However, the best result was obtained in the mixture [BMIM][PF₆]:TBME (1:1 v/v) at 50°C. Enzyme activity and selectivity in [BMIM][PF₆]:TBME (1:1 v/v) was slightly higher in than in conventional organic solvents (for example, TBME), and in this condition, good activity and enantioselectivity were associated with unique properties of ionic liquid such as hydrophobicity and high polarity. Independently of solvents, monester of (R)‐configuration was obtained in excess. Under optimal conditions, desymmetrization of the prochiral compound using different acyl donors was performed. If vinyl butyrate was used as the acylating agent, BCL completely selectively acylated enantiotopic hydroxyl groups.     

Recombination Losses Above and Below the Transport Percolation Threshold in Bulk Heterojunction Organic Solar Cells

Achieving the highest power conversion efficiencies in bulk heterojunction organic solar cells requires a morphology that delivers electron and hole percolation pathways for optimized transport, plus sufficient donor:acceptor contact area for near unity charge transfer state formation. This is a significant structural challenge, particularly in semiconducting polymer:fullerene systems. This balancing act in the model high efficiency PTB7:PC70BM blend is studied by tuning the donor:acceptor ratio, with a view to understanding the recombination loss mechanisms above and below the fullerene transport percolation threshold. The internal quantum efficiency is found to be strongly correlated to the slower carrier mobility in agreement with other recent studies. Furthermore, second‐order recombination losses dominate the shape of the current density–voltage curve in efficient blend combinations, where the fullerene phase is percolated. However, below the charge transport percolation threshold, there is an electric‐field dependence of first‐order losses, which includes electric‐field‐dependent photogeneration. In the intermediate regime, the fill factor appears to be limited by both first‐ and second‐order losses. These findings provide additional basic understanding of the interplay between the bulk heterojunction morphology and the order of recombination in organic solar cells. They also shed light on the limitations of widely used transport models below the percolation threshold.     

Scalable Water‐Based Production of Highly Conductive 2D Nanosheets with Ultrahigh Volumetric Capacitance and Rate Capability

Highly conductive and ultrathin 2D nanosheets are of importance for the development of portable electronics and electric vehicles. However, scalable production and rational design for highly electronic and ionic conductive 2D nanosheets still remain a challenge. Herein, an industrially adoptable fluid dynamic exfoliation process is reported to produce large quantities of ionic liquid (IL)‐functionalized metallic phase MoS₂ (m‐MoS₂) and defect‐free graphene (Gr) sheets. Hybrid 2D–2D layered films are also fabricated by incorporating Gr sheets into compact m‐MoS₂ films. The incorporated IL functionalities and Gr sheets prevent aggregation and restacking of the m‐MoS₂ sheets, thereby creating efficient and rapid ion and electron pathways in the hybrid films. The hybrid film with a high packing density of 2.02 g cm^?3 has an outstanding volumetric capacitance of 1430.5 F cm^?3 at 1 A g^?1 and an extremely high rate capability of 80% retention at 1000 A g^?1. The flexible supercapacitor assembled using a polymer‐gel electrolyte exhibits excellent resilience to harsh electrochemical and mechanical conditions while maintaining an impressive rate performance and long cycle life. Successful achievement of an ultrahigh volumetric energy density (1.14 W h cm^?3) using an organic electrolyte with a wide cell voltage of ≈3.5 V is demonstrated.     

Extrinsic Movable Ions in MAPbI3 Modulate Energy Band Alignment in Perovskite Solar Cells

Ionic movement is considered awful in perovskite solar cells (PSCs) for relating with the hysteresis and long‐term instability. However, the positive role of ions to enhance the energy band bending for high performance PSC is always overlooked, let alone reducing the hysteresis. In this work, LiI is doped in CH₃NH₃PbI₃. It is observed that the aggregation of Li⁺/I^? tunes the energy level of the perovskite and induces n/p doping in CH₃NH₃PbI₃, which makes charge extraction quite efficient from perovskite to both NiO and [6,6]‐phenyl‐C61‐butyric acid methyl ester (PCBM) layer. Therefore, in NiO/LiI doped perovskite/PCBM solar cells, Li⁺ and I^? modulate the interface energy band alignment to facilitate the electron/hole transport and reduce the interface energy loss. On the other hand, n/p doping enlarges Fermi energy level splitting of the PSCs to improve the photovoltage. The performance of LiI doped PSCs is much higher with reduced hysteresis compared to the undoped solar cells. This work highlights the positive effect of selective ionic doping, which is promisingly important to design the stable and efficient PSCs.     

The Synergistic Effect of Cation and Anion of an Ionic Liquid Additive for Lithium Metal Anodes

Lithium metal anodes are steadily gaining more attention, as their superior specific capacities and low redox voltage can significantly increase the energy density of rechargeable batteries far beyond those of current Li‐ion batteries. Nonetheless, the relevant technology is still in a premature research stage mainly due to the uncontrolled growth of Li dendrites that ceaselessly cause unwanted side reactions with electrolyte. In order to circumvent this shortcoming, herein, an ionic liquid additive, namely, 1‐dodecyl‐1‐methylpyrrolidinium (Pyr1(12)⁺) bis(fluorosulfonyl)imide (FSI^?), for conventional electrolyte solutions is reported. The Pyr1(12)⁺ cation with a long aliphatic chain mitigates dendrite growth via the combined effects of electrostatic shielding and lithiophobicity, whereas the FSI^? anion can induce the formation of rigid solid–electrolyte interphase layers. The synergy between the cation and anion significantly improves cycling performance in asymmetric and symmetric control cells and a full cell paired with an LiFePO₄ cathode. The present study provides a useful insight into the molecular engineering of electrolyte components by manipulating the charge and structures of the involved molecules.     

Ionic regulation and Na+,K+-ATPase activity in gills and kidney of the Antarctic aglomerular cod icefish exposed to dilute sea water

When Notothenia neglecta was exposed to diluted, half strength, sea water for 6 h or 10 days, serum concentrations of Cl^-, Na⁺, K⁺ and Mg²⁺ did not differ from those of sea water controls. This indicates that the fish were capable of both short- and long-term regulation. Renal Na⁺,K⁺-ATPase activity decreased after a 6 h exposure to diluted sea water, but there were no differences between diluted sea water and controls after 10 days of exposure.     

Quantifying effects of soil heterogeneity on groundwater pollution at four sites in USA

Four sites located in the north-eastern region of the United States of America have been chosen to investigate the impacts of soil heterogeneity in the transport of solutes (bromide and chloride) through the vadose zone (the zone in the soil that lies below the root zone and above the permanent saturated groundwater). A recently proposed mathematical model based on the cumulative beta distribution has been deployed to compare and contrast the regions' heterogeneity from multiple sample percolation experiments. Significant differences in patterns of solute leaching were observed even over a small spatial scale, indicating that traditional sampling methods for solute transport, for example the gravity pan or suction lysimeters, or more recent inventions such as the multiple sample percolation systems may not be effective in estimating solute fluxes in soils when a significant degree of soil heterogeneity is present. Consequently, ignoring soil heterogeneity in solute transport studies will likely result in under- or overprediction of leached fluxes and potentially lead to serious pollution of soils and/or groundwater.The cumulative beta distribution technique is found to be a versatile and simple technique of gaining valuable information regarding soil heterogeneity effects on solute transport. It is also an excellent tool for guiding future decisions of experimental designs particularly in regard to the number of samples within one site and the number of sampling locations between sites required to obtain a representative estimate of field solute or drainage flux.     

Location and density labelling of acid invertase in aging discs of Daucus carota storage tissue

Cell walls prepared from aged discs by extraction in 0·1 M acetate buffer, pH 4·8, possess ionically bound acid invertase which can be removed from the wall by incubation in 1 M sodium chloride in 0·1 M acetate buffer, pH 4·8, and more firmly attached enzyme which is not removed. Cell walls prepared in 0·195 M phosphate-0·003 M citrate-buffer, pH 8·0, do not possess ionically bound enzyme. Ionically bound invertase is density labelled when discs are aged in 90% deuterium oxide suggesting that at least part of the increase in activity observed during aging is due to de novo protein synthesis.     

Tuning the voltage dependence of tetraethylammonium block with permeant ions in an inward-rectifier K+ channel.

To understand the role of permeating ions in determining blocking ion-induced rectification, we examined block of the ROMK1 inward-rectifier K+ channel by intracellular tetraethylammonium in the presence of various alkali metal ions in both the extra- and intracellular solutions. We found that the channel exhibits different degrees of rectification when different alkali metal ions (all at 100 mM) are present in the extra- and intracellular solution. A quantitative analysis shows that an external ion site in the ROMK1 pore binds various alkali metal ions (Na+, K+, Rb+, and Cs+) with different affinities, which can in turn be altered by the binding of different permeating ions at an internal site through a nonelectrostatic mechanism. Consequently, the external site is saturated to a different level under the various ionic conditions. Since rectification is determined by the movement of all energetically coupled ions in the transmembrane electrical field along the pore, different degrees of rectification are observed in various combinations of extra- and intracellular permeant ions. Furthermore, the external and internal ion-binding sites in the ROMK1 pore appear to have different ion selectivity: the external site selects strongly against the smaller Na+, but only modestly among the three larger ions, whereas the internal site interacts quite differently with the larger K+ and Rb+ ions.