Disparities between experimental and environmental conditions: Research steps toward making electrochemical water treatment a reality

Electrochemical water treatment is one of the key topics of environmental electrochemistry. Identifying electrocatalytic materials capable of electrogenerating high oxidant species in situ seems to have catalyzed researchers’ interest in these processes. While most studies have focused on ideal lab-made solutions, translation to higher technology readiness levels and commercialization requires reframing research questions in context of real water matrices. In this current opinion, we discuss disconnects that may occur when focusing on synthetic solution treatment rather than on real waters. Future research can fill the gaps identified herein, thus facilitating application of electrochemical water treatment technologies.     

An incompressible smoothed particle hydrodynamics scheme for Newtonian/non-Newtonian multiphase flows including semi-analytical solutions for two-phase inelastic Poiseuille flows

An incompressible smoothed particle hydrodynamics (ISPH) method is developed for the modeling of multiphase Newtonian and inelastic non-Newtonian flows at low density ratios. This new method is the multiphase extension of Xenakis et al, J. Non-Newtonian Fluid Mech., 218, 1-15, which has been shown to be stable and accurate, with a virtually noise-free pressure field for single-phase non-Newtonian flows. For the validation of the method a semi-analytical solution of a two-phase Newtonian/non-Newtonian (inelastic) Poiseuille flow is derived. The developed method is also compared with the benchmark multiphase case of the Rayleigh Taylor instability and a submarine landslide, thereby demonstrating capability in both Newtonian/Newtonian and Newtonian/non-Newtonian two-phase applications. Comparisons with analytical solutions, experimental and previously published results are conducted and show that the proposed methodology can accurately predict the free-surface and interface profiles of complex incompressible multi-phase flows at low-density ratios relevant, for example, to geophysical environmental applications.     

Ready Access to Anhydrous Anionic Lanthanide Acetates by Using Imidazolium Acetate Ionic Liquids as the Reaction Medium

Access to lanthanide acetate coordination compounds is challenged by the tendency of lanthanides to coordinate water and the plethora of acetate coordination modes. A straightforward, reproducible synthetic procedure by treating lanthanide chloride hydrates with defined ratios of the ionic liquid (IL) 1-ethyl-3-methylimidazolium acetate ([C₂mim][OAc]) has been developed. This reaction pathway leads to two isostructural crystalline anhydrous coordination complexes, the polymeric [C₂mim]_n[{Ln₂(OAc)₇}_n] and the dimeric [C₂mim]₂[Ln₂(OAc)₈], based on the ion size and the ratio of IL used. A reaction with an IL : Ln-salt ratio of 5 : 1, where Ln=Nd, Sm, and Gd, led exclusively to the polymer, whilst for the heaviest lanthanides (Dy−Lu) the dimer was observed. Reaction with Eu and Tb resulted in a mixture of both polymeric and dimeric forms. When the amount of IL and/or the size of the cation was increased, the reaction led to only the dimeric compound for all the lanthanide series. Crystallographic analyses of the resulting salts revealed three different types of metal-acetate coordination modes where η²μκ² is the most represented in both structure types.     

The value of foresight

Suppose you have one unit of stock, currently worth 1, which you must sell before time $T$. The Optional Sampling Theorem tells us that whatever stopping time we choose to sell, the expected discounted value we get when we sell will be 1. Suppose however that we are able to see $a$ units of time into the future, and base our stopping rule on that; we should be able to do better than expected value 1. But how much better can we do? And how would we exploit the additional information? The optimal solution to this problem will never be found, but in this paper we establish remarkably close bounds on the value of the problem, and we derive a fairly simple exercise rule that manages to extract most of the value of foresight.     

The (3+1)-dimensional Monge-Ampère equation in discontinuity wave theory: Application of a reciprocal transformation

It is shown that the complete exceptionality condition for discontinuity waves associated with a second-order non-linear hyperbolic equation of the form

Dual emission laser induced fluorescence for direct planar scalar behavior measurements

 In this paper, a new method of measuring scalar behavior in bulk aqueous fluid flows is presented. Using a simple ratiometric scheme, laser induced fluorescence from organic dyes can be normalized so that direct measurements of a scalar in the flow are possible. The technique dual emission laser induced fluorescence (DELIF) relies on normalizing the fluorescence emission intensity of one dye with the fluorescence emission intensity of a second dye. Since each dye fluoresces at a different wavelength, one can optically separate the emission of each dye. This paper contains an overview of the basic ratiometric technique for pH and temperature measurements as well as the spectral properties of nine water soluble dyes. It also covers the three most significant sources of error in DELIF applications. To demonstrate the technique, steady state turbulent jet mixing and temperature fields in a thermal plume were quantified. The accuracy was camera limited at under 3% of the fluorescence ratio which corresponds to 0.1 pH units or 1.8 °C. Received 7 June 1996/Accepted 17 June 1997     

Benzene Solubility in Ionic Liquids: Working Toward an Understanding of Liquid Clathrate Formation

The solubility of benzene in 15 imidazolium, pyrrolidinium, pyridinium, and piperidinium ionic liquids has been determined; the resulting, benzene‐saturated ionic liquid solutions, also known as liquid clathrates, were examined with ¹H and ¹⁹F nuclear magnetic resonance spectroscopy to try and understand the molecular interactions that control liquid clathrate formation. The results suggest that benzene interacts primarily with the cation of the ionic liquid, and that liquid clathrate formation (and benzene solubility) is controlled by the strength of the cation–anion interactions, that is, the stronger the cation–anion interaction, the lower the benzene solubility. Other factors that were determined to be important in the final amount of benzene in any given liquid clathrate phase included attractive interactions between the anion and benzene (when significant), and larger steric or free volume demands of the ions, both of which lead to greater benzene solubility.     

Profiling of the secretome of human cancer cells: Preparation of supernatant for proteomic analysis

Secretomic analysis requires removal of serum proteins from cell‐culture media. We evaluate the proteins washed from cells prepared in bovine serum‐supplemented medium. PBS and serum‐free‐medium (SFM) were the washing solutions. A Bradford assay was used for total protein concentration and a 1D gel and LC‐MS/MS, to assign the protein to human or bovine origin. For both wash solutions, all bovine protein had been removed by the third wash, without compromising the number of living cells. Further washes reduced the number of living cells, especially when using PBS. Proteomic analysis of wash supernatant showed that SFM induced greater lysis of dead cells. Three washes were sufficient to minimize the effects on cell viability, while still removing serum proteins. Washing in SFM resulted in contamination of the wash supernatant with lysed dead cell proteins. Washed cells were incubated in SFM and exposed to ionizing radiation. Analysis of the supernatant showed an increase in human cytoplasmic, plasma membrane, and nuclear protein following irradiation. Secreted proteins were also detected, but in smaller quantities. The significance of these findings extend to in vitro studies of bystander phenomena, since the proteins of lysed dead cells may participate in driving bystander responses.     

Ionic Fluids Containing Both Strongly and Weakly Interacting Ions of the Same Charge Have Unique Ionic and Chemical Environments as a Function of Ion Concentration

Liquid multi‐ion systems made by combining two or more salts can exhibit charge ordering and interactions not found in the parent salts, leading to new sets of properties. This is investigated herein by examining a liquid comprised of a single cation, 1‐ethyl‐3‐methylimidazolium ([C₂mim]⁺), and two anions with different properties, acetate ([OAc]^?) and bis(trifluoromethylsulfonyl)imide ([NTf₂]^?). NMR and IR spectroscopy indicate that the electrostatic interactions are quite different from those in either [C₂mim][OAc] or [C₂mim][NTf₂]. This is attributed to the ability of [OAc]^? to form complexes with the [C₂mim]⁺ ions at greater than 1:1 stoichiometries by drawing [C₂mim]⁺ ions away from the less basic [NTf₂]^? ions. Solubility studies with molecular solvents (ethyl acetate, water) and pharmaceuticals (ibuprofen, diphenhydramine) show nonlinear trends as a function of ion content, which suggests that solubility can be tuned through changes in the ionic compositions.