Ionic Liquids and their Polymers in Lithium‐Sulfur Batteries

Future optimized lithium‐sulfur batteries may promise higher energy densities than the current standard. However, there are many barriers which hinder their commercialization. In this review we describe how ionic liquids (ILs) and their polymers are utilized in different components of the battery to address some of these issues. For example, IL‐based electrolytes have the potential to reduce the solubility of polysulfides compared to conventional organic electrolytes. Polymerizing ILs directly on the surface of the Li‐metal anode is suggested as an approach to protect the surface of this electrode. Finally, using poly(ionic liquids) (PILs) as binders for the cathode active material may increase the performance of the cathode as compared to polyvinylidene difluoride (PVdF) and could inhibit swelling‐induced degradation. These results demonstrate the advantages of ILs and their polymers for improving the performance of Li?S batteries.     

Experimental proof of a chromatographic paradox: are the injected molecules in the peak?

Forty years ago Helfferich and Peterson published an article in Science regarding a "paradoxical" behavior in nonlinear chromatography (Helfferich, F.; Peterson, D. L. Science 1963, 142, 661-662). They theoretically predicted that when an excess of sample molecules is injected into a chromatographic column that is equilibrated with a constant stream of identical molecules, the observed peak will not contain the injected molecules. Instead the observed peak will only contain molecules from the stream whereas the injected molecules will exit the column in a slower moving, "invisible" peak. They considered it paradoxical that a single injection in a single-component system could cause the successive elution of two peaks (Helfferich, F. J. Chem. Educ. 1964, 41, 410-413). In this study, the paradox is experimentally proven for the first time. Two different strategies were employed: (i) a radiochemical approach and (ii) a method based on the use of two enantiomers in a nonchiral separation system. The experiments were compared with computer simulations.     

Validation of the accuracy of the perturbation peak method for determination of single and binary adsorption isotherm parameters in LC

An analytical validation of the precision and accuracy of the perturbation peak (PP) method for determination of single and competitive thermodynamic isotherm parameters was performed using frontal analysis as a reference. The isotherm parameters of 11alpha-hydroxyprogesterone were determined in an achiral system and the isotherm parameters of (+)-methyl L-mandelate and (-)-methyl D-mandelate were determined in a chiral system, both for the single components and for the competitive binary mixture. The experimental errors in the PP method using different injection techniques were investigated, and we devised a new injection technique for the determination of competitive isotherm parameters that considerably reduced the experimental errors and also made both perturbation peaks detectable. We showed that the PP method with the new injection technique can be used to determine isotherm parameters directly from a racemic mixture. These parameters agreed well with those determined using several enantiomer ratios. Elution-band profiles simulated using the isotherm parameters showed excellent agreement with experimental profiles.     

Estimation of the Transient Surface Temperature,Heat Flux and Effective Heat Transfer Coefficient of a Slab in an Industrial Reheating Furnace by using an Inverse Method

In the steel industry it is of great importance to be able to control the surface temperature and heating or cooling rates during heat treatment processes. In this paper, a steel slab is heated up to 1300°C in an industrial reheating furnace and the temperature data are recorded during the reheating process. The transient local surface temperature, heat flux and effective heat transfer coefficient of the steel slab ares calculated using a model for inverse heat conduction. The calculated surface temperatures are compared with the temperatures achieved by using a model of the heating process with the help of the software STEELTEMP® 2D. The results obtained show very good agreement and suggest that the inverse method can be applied to similar high temperature applications with very good accuracy.     

Experimental prediction of sheet metal formability of AW-5754 for non-linear strain paths by using a cruciform specimen and a blank holder with adjustable draw beads on a sheet metal testing machine

The main objective to guarantee a high efficiency in the press shop is to produce sheet metal parts without failure. The feasibility of sheet metal parts is nowadays ensured during the development process by a comparison of the occurring strains in the simulation with the Forming Limit Diagram (FLD). The principle of the experimental procedure to determine the FLD is standardized in ISO 12004–2 [1]. This procedure is only valid with high accuracy for proportional unbroken strain paths. However, in most industrial forming operations non-linear strain paths occur. To resolve this problem, a phenomenological approach was introduced by Volk [2], the so-called Generalized Forming Limit Concept (GFLC). Localized necking and the remaining formability for any arbitrary non-linear strain path can be predicted with the GFLC. Furthermore, experimental investigation of multi-linear strain paths appears highly complex in practice and involves a range of testing equipment, e.g. different specimens, testing machines and tools. In this paper an alternative method is introduced by using a cruciform specimen and a draw bead tool on a sheet metal testing machine. The different draw bead heights allow the creation of arbitrary strain states, which can be changed at different height of the punch. Conventionally cruciform specimens are used to determine the yield loci in the first quadrant of the stress space at low strain values. To enable a cruciform specimen for the evaluation of strain limits comparable to the conventional Nakajima test, an optimization of the geometry regarding the maximum achievable strains in the specimen center takes place. The developed specimen and tool allow testing of materials under multi-axial strain states with a reduced testing effort.     

Hematite Photoanodes: Synergetic Enhancement of Light Harvesting and Charge Management by Sandwiched with Fe2TiO5/Fe2O3/Pt Structures

Efficient charge separation and transport as well as high light absorption are key factors that determine the efficiency of photoelectrochemical (PEC) water splitting devices. Here, a PEC device consisting of a hematite nanoporous film deposited on Pt nanopillars, followed by the decoration with an Fe₂TiO₅ passivation layer, is designed and fabricated. This structure can largely improve the light absorption in the composite materials, and significantly enhance the water oxidation performance of hematite photoanodes. The Fe₂TiO₅ thin shell and Pt underlayer significantly improve the interfacial charge transfer while minimizing the hole‐migration length in Fe₂O₃ photoanodes, leading to a drastically increased photocurrent density. Specially, the Fe₂TiO₅/Fe₂O₃/Pt photoanode yields an excellent photoresponse for PEC water splitting reactions with 1.0 and 2.4 mA cm^?2 obtained at 1.23 and 1.6 V_RHE under AM 1.5G illumination in 1 m KOH. The resulting photocurrents are 2.5 times enhanced compared to a pristine Fe₂O₃ photoanode of the same geometry. These results demonstrate a synergistic charge transfer effect of Fe₂TiO₅ and Pt layers on hematite for the improvement of PEC water oxidation.     

Bayesian state estimation of a flexible industrial robot

A sensor fusion method for state estimation of a flexible industrial robot is developed. By measuring the acceleration at the end-effector, the accuracy of the arm angular position, as well as the estimated position of the end-effector are improved. The problem is formulated in a Bayesian estimation framework and two solutions are proposed; the extended Kalman filter and the particle filter. In a simulation study on a realistic flexible industrial robot, the angular position performance is shown to be close to the fundamental Cramér-Rao lower bound. The technique is also verified in experiments on an ABB robot, where the dynamic performance of the position for the end-effector is significantly improved.     

Local Approximability of Max-Min and Min-Max Linear Programs

In a max-min LP, the objective is to maximise ω subject to A x≤1, C x≥ω 1, and x≥0. In a min-max LP, the objective is to minimise ρ subject to A x≤ρ 1, C x≥1, and x≥0. The matrices A and C are nonnegative and sparse: each row a _i of A has at most Δ _I positive elements, and each row c _k of C has at most Δ _K positive elements.     

Engineering of the Electron Transport Layer/Perovskite Interface in Solar Cells Designed on TiO2 Rutile Nanorods

The engineering of the electron transport layer (ETL)/light absorber interface is explored in perovskite solar cells. Single‐crystalline TiO₂ nanorod (NR) arrays are used as ETL and methylammonium lead iodide (MAPI) as light absorber. A dual ETL surface modification is investigated, namely by a TiCl₄ treatment combined with a subsequent PC₆₁BM monolayer deposition, and the effects on the device photovoltaic performance were evaluated with respect to single modifications. Under optimized conditions, for the combined treatment synergistic effects are observed that lead to remarkable enhancements in cell efficiency, from 14.2% to 19.5%, and to suppression of hysteresis. The devices show J_SC, V_OC, and fill factor as high as 23.2 mA cm^?2, 1.1 V, and 77%, respectively. These results are ascribed to a more efficient charge transfer across the ETL/perovskite interface, which originates from the passivation of defects and trap states at the ETL surface. To the best of our knowledge, this is the highest cell performance ever reported for TiO₂ NR‐based solar cells fabricated with conventional MAPI light absorber. Perspective wise, this ETL surface functionalization approach combined with more recently developed and better performing light absorbers, such as mixed cation/anion hybrid perovskite materials, is expected to provide further performance enhancements.