Ionic liquids are increasingly employed as dielectrics to generate high charge densities and enable low‐voltage operation with organic semiconductors. However, effects on structure and morphology of ...the active material are not fully known, particularly for permeable semiconductors such as conjugated polymers, in which ions from the ionic liquid can enter and electrochemically dope the semicrystalline film. To understand when ions enter, where they go, and how they affect the film, thin films of the archetypal semiconducting polymer, poly(3‐hexylthiophene), are electrochemically doped with 1‐ethyl‐3‐methylimidazolium bis(trifluoromethylsulfonyl)imide, the archetypal ionic liquid. High‐resolution, ex situ X‐ray diffraction measurements and complete pole figures reveal changes with applied voltage, cycling, and frequency in lattice spacing, crystallite orientation, and crystallinity in the bulk and at the buried interface. Dopant ions penetrate the film and enter the crystallites at sufficiently high voltages and low frequencies. Upon infiltrating crystallites, ions permanently expand lamellar stacking and contract pi‐stacking. Cycling amplifies these effects, but higher frequencies mitigate the expansion of bulk crystallites as ions are hindered from entering crystallites. This mechanistic understanding of the structural effects of ion penetration will help develop models of the frequency and voltage impedance response of electrochemically doped conjugated polymers and advance electronic applications.
X‐ray characterization reveals two regimes of structural change in thin films of polymer poly(3‐hexylthiophene) gated through 1‐ethyl‐3‐methylimidazolium bis(trifluoromethylsulfonyl)imide. Tracking how ion penetration affects lattice spacing, crystalline orientation, and crystallinity elucidates mechanisms of the structural changes induced. Ions penetrate the film and enter crystallites at sufficiently high voltages and low frequencies. Cycling amplifies changes, though some effects are mitigated at higher frequencies.
Mechanochemistry, a resurging synthetic approach, has been developed into an effective and controllable method to access a family of crystalline porous catechol-derived metal–organic frameworks ...(MOFs) for the first time. We have identified that the obtained crystalline phase is readily tunable by precursors and the addition of solvents or drying agents. The described mechanochemistry allows us to synthesize these materials in a highly sustainable manner. Thus, mechanochemistry is expected to pave a promising avenue to access a broader class of MOF materials, in addition to those based on the motifs of carboxylic acid or imidazole.
This paper focuses on the development of error estimators for evaluating the accuracy of finite element computations of the electromagnetic phenomena for electromagnetic material processing ...modelling. The ultimate goal of this work is to enable adaptive anisotropic remeshing in order to reach a prescribed accuracy. We first introduce a numerical model based on the quasi-steady state approximation of the Maxwell's equations in a time-domain formalism. We then introduce an estimator based on a recovery method; its results will be compared with other estimators based on investigating how accurately some of the electromagnetic equations are checked. The estimators are then validated on analytical cases; an additional application to a complex case shows the robustness of our approach. Scientific advances of this work include the development of a robust field recovery strategy for error computation, as well as the introduction of a general purpose error normalization scheme which overcomes field scale bias enabling seamless comparison of errors from different physical fields.
•We proposed three constructive heuristics for the open shop scheduling problem with setup times.•We propose a hybrid genetic algorithm for the open shop scheduling problem with setup times.•We ...compare the proposals with existing approximate algorithms.•We suggest that our meta-heuristic is is the best-so-far algorithm for the problem under study.
In the open shop scheduling problem with sequence-dependent setup times, there is no established order for the processing of the jobs, which leads to a large number of possible solutions for the scheduling problem. Furthermore, there is a setup time between two consecutive operations, which depends on the job previously processed. In this work we propose a hybrid genetic algorithm for the OSSP with sequence-dependent setup times and total completion time minimization as objective function. Our proposal uses two novel constructive heuristics which are combined for the generation of the initial population. We carry out an extensive computational experience using problem instances taken from the related literature to evaluate the performance of the proposed algorithms as compared to existing heuristics for the problem. The quality of the solutions and the CPU time required are used as performance criteria. Among them, the genetic algorithm with direct decoding presents a smaller value for the average relative percentage deviation in comparison with the electromagnetic algorithm proposed by Naderi et al. (2011). The computational results prove the excellent performance of the proposed metaheuristic for the tested instances, resulting in the most efficient algorithm so-far for the problem under consideration.
The purpose of this study was to compare the diagnostic accuracy of MRI, MR arthrography, and ultrasound for the diagnosis of rotator cuff tears through a meta-analysis of the studies in the ...literature.
Articles reporting the sensitivities and specificities of MRI, MR arthrography, or ultrasound for the diagnosis of rotator cuff tears were identified. Surgical (open and arthroscopic) reference standard was an inclusion criterion. Summary statistics were generated using pooled data. Scatterplots of the data sets were plotted on a graph of sensitivity versus (1 - specificity). Receiver operating characteristic (ROC) curves were generated.
Sixty-five articles met the inclusion criteria for this meta-analysis. In diagnosing a full-thickness tear or a partial-thickness rotator cuff tear, MR arthrography is more sensitive and specific than either MRI or ultrasound (p < 0.05). There are no significant differences in either sensitivity or specificity between MRI and ultrasound in the diagnosis of partial- or full-thickness rotator cuff tears (p > 0.05). Summary ROC curves for MR arthrography, MRI, and ultrasound for all tears show the area under the ROC curve is greatest for MR arthrography (0.935), followed by ultrasound (0.889) and then MRI (0.878); however, pairwise comparisons of these curves show no significant differences between MRI and ultrasound (p > 0.05).
MR arthrography is the most sensitive and specific technique for diagnosing both full- and partial-thickness rotator cuff tears. Ultrasound and MRI are comparable in both sensitivity and specificity.
•New valid inequalities are described.•An approach to reduce the size of a multi-commodity formulation is proposed.•Multi-start randomized bottom-up dynamic programming-based heuristic is ...presented.•Approaches could obtain solutions with low gaps in short computational times.
We consider the uncapacitated three-level lot-sizing and replenishment problem with a distribution structure. In this problem, a single production plant sends the produced items to replenish warehouses from where they are dispatched to the retailers in order to satisfy their demands over a finite planning horizon. Transfers between warehouses or retailers are not permitted, each retailer has a single predefined warehouse from which it receives its items, and there is no restriction on the amount that can be produced or transported in a given period. The goal of the problem is to determine an integrated production and distribution plan minimizing the total costs, which comprehends fixed production and transportation setup as well as variable inventory holding costs. We describe new valid inequalities both in the space of a standard mixed integer programming (MIP) formulation and in that of a new alternative extended MIP formulation. We show that using such extended formulation, valid inequalities having similar structures to those in the standard one allow achieving tighter linear relaxation bounds. Furthermore, we propose a preprocessing approach to reduce the size of an extended multi-commodity MIP formulation available in the literature. Such preprocessing relies on the removal of variables based on the problem’s cost structure while preserving optimality guarantees. We also propose a multi-start randomized bottom-up dynamic programming-based heuristic. The heuristic employs greedy randomization via changes in certain costs and solves subproblems related to each level using dynamic programming. Computational experiments indicate that the use of the valid inequalities in a branch-and-cut approach significantly increase the ability of a MIP solver to solve instances to optimality. Additionally, the valid inequalities for the new alternative extended formulation outperform those for the standard one in terms of number of solved instances, running time and number of enumerated nodes. Moreover, the proposed heuristic is able to generate solutions with considerably low optimality gaps within very short computational times even for large instances. Combining the preprocessing approach with the heuristic, one can achieve an increase in the number of solutions solved to optimality within the time limit together with significant reductions on the average times for solving them.
•We propose a column generation (CG) rounding heuristic with an LP/MIP repair method;•We also present relax-and-fix (RF) and fix-and-optimize (FO) heuristics;•Combining the CG rounding heuristic with ...FO outperforms state-of-the-art approaches;•Best known solutions are found in 86.85% of the cases, 69.72% are new best solutions;•Optimality gaps are always below 5.54% for the tested set of instances.
Effective Mixed Integer Programming (MIP) based matheuristics for the multi-item capacitated lot-sizing problem with remanufacturing (CLSP-RM) are proposed in this paper. This NP-hard problem consists of determining an optimal plan for the capacitated production and remanufacture of multiple items in order to satisfy their deterministic dynamic demands over a discrete time horizon. Two constructive approaches are proposed: a column generation rounding heuristic followed by a Linear Programming (LP)/MIP repairing mechanism, and a relax-and-fix method. A fix-and-optimize local search procedure is also applied to improve the quality of the solutions obtained by the constructive techniques. Computational results show that the new approach combining a column generation rounding heuristic with a fix-and-optimize local search procedure is very competitive with the state-of-the-art heuristic. Specifically, the obtained solutions are at least as good as the best known in the literature for 86.85% of the instances, with new best solutions encountered for 69.72% of them. Moreover, all obtained solutions are within 5.54% of optimality, showing the robustness of the newly proposed approach.
The cyanotoxin cylindrospermopsin (CYN) is the second biggest cause of poisoning worldwide, both in humans and animals. Although CYN primarily affects the aquatic environments and can be absorbed in ...fishes by multiple routes, data reporting its toxicity and mechanism of action are still scarce in this group. Using P. reticulata as model species, it was evaluated whether CYN promotes mutagenic and genotoxic effects in different fish target tissues. Adult females were exposed in a static way to 0 (control), 0.5, 1.0, and 1.5 μg L−1 of pure CYN for 24 and 96 hours. For the first time, DNA damage was detected in fish brain after CYN exposition. In brain cells, a concentration‐response DNA damage was observed for both exposure times, suggesting a direct or indirect action of CYN in neurotoxicity. For the liver cells, 96 hours caused an increase in DNA damage, as well the highest percentage of DNA in the tail was reached when used 1.5 μg L−1 of CYN. In peripheral blood cells, an increase in DNA damage was observed for all tested concentrations after 96 hours. In erythrocytes, micronuclei frequency was higher at 1.5 μg L−1 treatment while the erythrocyte nuclear abnormalities (ENA) frequency was significantly higher even at the lowest CYN concentration. Such data demonstrated that acute exposition to CYN promotes genotoxicity in the brain, liver, and blood cells of P. reticulata, as well mutagenicity in erythrocytes. It rises an alert regarding to the toxic effects of CYN for aquatic organisms as well as for human health.
The detonation failure process, specifically where a transient reaction occurs in an overdriven explosive due to a sub-critical charge diameter, has remained relatively unexplored, particularly ...regarding its relationship to shock initiation mechanisms. Detonation failure, here defined as a weakly supported shock wave traveling with a decaying velocity, of aluminized ammonium nitrate (AN/Al) was considered to investigate the relationship between the detonation failure process and shock sensitivity. Previous work has shown that the Al additive particle size alters the failure diameter, a measure of shock sensitivity, of AN/Al. Microwave interferometry was used to measure the transient shock wave velocity in the explosive system, which was lightly confined at a diameter below its critical diameter, in response to an overdriven shock insult in a small-scale experiment. An array of mixture ratios and particle size distributions of the explosive system was used to vary the sensitivity of the explosive and to facilitate exploration of the relationship between the shock velocity decay rate, initiation mechanisms, and large-scale shock sensitivity. Resulting shock velocity profiles in AN/Al indicate that micron-sized and larger Al particles can contribute to the detonation process. It is concluded that the rate at which the transient shock velocity approaches that of a compressive wave with no supporting reaction corresponds to the relative shock sensitivity of the system; it is therefore proposed that the measured shock velocity decay rate of an overdriven sub-critical diameter charge of AN/Al reveals quantifiable information about the relative shock sensitivity of a large-scale charge.
This work aims to develop an adaptive remeshing procedure for the finite-element method (FEM) on electromagnetic computations. A thorough comparison of metric computation strategies is carried out as ...it constitutes a cornerstone of this development. This procedure will focus on the mesh size adaptation to distribute the error uniformly over a computational domain, to achieve a user-prescribed solution accuracy. Also, it shall enable dealing with complex geometries for electromagnetic-coupled material processing applications. For this purpose, a quasi-steady-state approximation of Maxwell’s equations in a time-domain formalism is considered. The automatic remeshing procedure is based on the following key steps: An a posteriori error estimator to pinpoint the critical areas needing refinement or allowing coarsening. An anisotropic metric approximation. Both steps use a global field recovery algorithm to enable robust gradient computation. Finally, several 3-D test cases are presented.
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