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Breaking the PFAS Chain: Piezocatalytic Decomposition of Forever Chemicals Using BaTiO3 Nanoparticles
No full textPer- and polyfluoroalkyl substances (PFAS) pose significant environmental and health risks due to their ubiquitous presence and persistence in water systems. In this study, we investigate the efficacy of piezocatalysis using barium titanate (BTO) nanoparticles under ultrasound irradiation for the degradation and defluorination of perfluorooctane sulfonate (PFOS) in water. The research demonstrates a substantial 90.5% degradation and 29% defluorination of PFOS after six hours of treatment, highlighting the potential of piezocatalysis as a promising approach for PFAS degradation. Additionally, the quantification of degradation products elucidates the transformation pathways of PFOS, suggesting a stepwise chain-shortening mechanism. Our findings underscore the importance of continued research in optimizing piezocatalytic processes and exploring synergistic approaches with other advanced oxidation methods to effectively address PFAS contamination challenges. These efforts are essential for advancing sustainable water treatment strategies and mitigating the environmental and health hazards associated with PFAS contamination
SPCal - An open source, easy-to-use processing platform for ICP-TOFMS based single event data
No full textSingle particle inductively coupled plasma – mass spectrometry (SP ICP-MS) has evolved into one of the most powerful techniques for the bottom-up characterisation of nanoparticle suspensions. The latest generations of time-of-flight mass analysers offer new perspectives on single particles by rapidly collecting full mass spectra and providing information on particle composition and abundances even in unknown samples. However, SP ICP-TOFMS is associated with vast data sizes with complex structure, which can hamper its applicability and the interrogation of specific particle features. Unlocking the full potential of SP ICP-TOFMS requires dedicated, easy-to-use software solutions to navigate through data sets and promote transparent, efficient and precise processing. SPCal is an open-source SP data processing platform, which we have previously released for quadrupole-based data. In this work, we expand its reach by enabling the analysis of TOF-based SP data sets additionally. We have incorporated various tools to facilitate the handling, manipulation and calibration of large data sets and provide the required statistical fundament and models to promote accurate thresholding. Non-target screening tools are integrated to pinpoint particulate elements in unknown samples without the requirement for a-priori investigations or modelling. Next to basic functions like the calibration of size and mass distributions, methods to carry out cluster analysis (PCA, HAC) provide the means to study groups of particles based on their composition and conditional data filtering allows the interrogation of particle populations by selectecting specific features
Asymmetric Syntheses of Aziridine-2-carboxylates via Reductive Kinetic Resolution of 2H-Azirines
No full textEnantioenriched aziridine-2-carboxylates are valuable organic compounds thanks to their versatility as chiral building blocks. Several syntheses of bioactive molecules employ aziridine-2-carboxylates as a crucial synthetic intermediate, e.g. the total synthesis of dynobacin A. However, traditional strategies only access N-protected aziridines, which are poorly stable and can undergo unwanted side reactions as ring-opening. Herein, we present the first copper hydride kinetic resolution of racemic 2H-azirines for the asymmetric preparation of N-H aziridine-2-carboxylates and the corresponding enantioenriched 2H-azirines. This is relevant as N-H aziridine-2-carboxylates are a generally bench stable and easily diversifiable building block. After an extensive catalyst screening and reaction optimization, the N-H aziridines were obtained with excellent diastereoselectivity (>20:1) and high enantioselectivity (up to 94%). Additionally, we conducted a Hammett study and we observed a linear free energy relationship between the ΔΔG⧧ of the diastereomeric transition states and the σp- values
Probabilistic Deconvolution of the Distribution of Relaxation Times from Multiple Electrochemical Impedance Spectra
No full textElectrochemical impedance spectroscopy (EIS) is widely used to study the properties of electrochemical materials and systems. However, analyzing EIS data remains challenging. Among various analysis methods, the distribution of relaxation times (DRT) has emerged as a novel non-parametric approach capable of providing timescale information. Among the various DRT inversion methods, those based on Gaussian processes (GP) are particularly promising because they provide uncertainty estimates for both EIS and DRT. However, current GP-based DRT implementations can only handle one spectrum at a time. This work extends these models to allow concurrent analysis of multiple impedance spectra as a function of experimental conditions. The new method, called the quasi-Gaussian process distribution of relaxation times, treats the DRT as a GP with respect to the experimental state and as a finite approximation of a positively constrained GP with respect to timescales. This new DRT inversion approach is validated against noise-corrupted artificial EIS data and applied to experimental data, allowing us to expedite EIS data analysis of multiple EIS data from a probabilistic perspective
Visible-Light-Driven Synthesis of Alkenyl Thiocyanates: Novel Building Blocks for Diverse Sulfur-Containing Molecular Assembly
No full textThe first visible-light-induced protocol for the general preparation of alkenyl thiocyanates from alkenyl bromides is presented. The reaction is simple, proceeds under very mild conditions and demonstrates broad functional group tolerance. Additionally, a flow protocol was developed to enable efficient scale-up of alkenyl thiocyanate synthesis, further enhancing the practicality and value of the method. Importantly, these alkenyl thiocyanates serve as valuable building blocks for the construction of diverse families of sulfur-containing molecules through trifluoromethylation, cycloaddition, oxidations, and C–S or C–P bond forming reactions
pKa Prediction in Non-Aqueous Solvents
No full textAcid dissociation constants (pKa) are widely measured and studied, most typically in water. Comparatively few datasets and models for non-aqueous pKa values exist. In this work, we demonstrate how the pKa in one solvent can be accurately determined using reference data in another solvent, corrected by solvation energy calculations from the COSMO-RS method. We benchmark this approach in ten different solvents, and find that pKa values calculated in six solvents deviate from experimental data on average by less than 1 pH unit. We observe comparable performance on a more diverse test set including amino acids and drug molecules, with higher error for large molecules. The model performance in four other solvents is worse, with some MAEs exceeding 3 pH units; we discuss how such errors arise due to both model error and inconsistency in data calibration. Finally, we demonstrate how this technique can be used to estimate the proton transfer energy between different solvents, and use this to report a value of the proton’s solvation energy in formamide, a quantity that has does not have a consensus value in literature
Organic Ionic Plastic Crystal/PVDF Composites Prepared by Solution Casting
No full textSolid-state electrolytes have been considered as a promising candidate to address the safety issues for next-generation lithium batteries. Organic ionic plastic crystals (OIPCs) are attracting increasing interest as solid electrolyte materials due to their unique advantages. In this study, an OIPC-based composite electrolyte consisting of the OIPC 1-ethyl-1-methylpyrrolidinium bis(trifluoromethylsulfonyl)imide (Pyr12TFSI), lithium bis(trifluoromethylsulfonyl)imide (LiTFSI) and the polymer polyvinylidene fluoride (PVDF) has been developed by a facile solution casting strategy. Free-standing and flexible OIPC/polymer composite membranes were fabricated by the solution casting method, which not only provides flexibility and better electrode/electrolyte contact, but also is more compatible with current battery processing methods. The thermal behavior and ionic conductivity of the OIPC-based composites with different molar proportions (10 mol% to 67 mol%) of LiTFSI in LiTFSI/Pyr12TFSI as well as different weight fractions (20 wt% to 50 wt%) of PVDF were studied to understand the effect on transport properties. Among all the compositions studied, the Li0.33Pyr0.67TFSI/30wt%PVDF composite exhibited high ionic conductivity (e.g. 1.2 × 10−4 S cm-1 at 30 °C). The Li0.33Pyr0.67TFSI/30wt%PVDF composite membrane was evaluated in Li/Li symmetric cell and was cycled stably over 900 h at a current density of 0.1 mA cm−2 at 50 °C, demonstrating that this OIPC/polymer composite electrolyte enabled the reversible and stable lithium plating and stripping behaviors. Further tests of the Li0.33Pyr0.67TFSI/30wt%PVDF composite membrane as solid electrolyte in LiFePO4/Li cell presented a high specific capacity of 149 mAh g−1 at 0.1 C and a long cycle life of over 440 cycles with capacity retention of 89% at 0.5 C at 50 °C, which showed improved rate capability and cycling stability in comparison with the composites with similar compositions but obtained by powder pressing method. This study demonstrated the potential of the OIPC/polymer composite solid electrolyte prepared by solution casting method and will promote the development of high-performance OIPC-based composite electrolytes for solid-state batteries
Outmost Cationic Surface Charge of Layer-by-Layer Films Prevent Endothelial Cells Migration in Three-dimensional Tissues
No full textTissues and organs possess an organized cellular arrangement that enables their unique functions. However, conventional three-dimensional (3D) encapsulation techniques fail to recapitulate this complexity due to the cell migration during cell culture. In biological tissues, basement membranes (BMs) are essential to mechanically support cellular organization. In this study, we found that positively-charged outmost surface of multilayered nanofilms, fabricated through LbL assembly of poly-L-lysine (PLL) and dextran (Dex) via hydrogen bonds, stimulated the barrier functions of BMs. This type of artificial BMs (A-BMs) demonstrate enhanced barrier properties in comparison to other type ofA-BMs composed of BM component such as collagen type IV and laminin. Such an enhancement is potentially associated with the outmost positive layer, which inhibits the sprouting of endothelial cells (ECs) and effectively prevents EC migration over a 14-day period, aligning with the regeneration timeline of natural BMs in 3D tissues. In the end, 3D organized vascular channels are successfully engineered through the sequential processes of spreading smooth muscle cells (SMCs), in-situ assembly of PLL/Dex nanofilms and endothelialization of ECs, which would provide a reliable platform for evaluating the efficacy of drugs, investigating nanotoxicology, and advancing the development of regenerative medicine
Unraveling the structure and composition of Li4Mn2O4.5 (Li2O•Li0.667Mn1.333O2) electrodes for lithium batteries
No full textThis communication addresses the debate about the composition and structure of a lithium-rich manganese oxide electrode with a fully disordered Li-Mn-O rock salt component that was first reported as Li4Mn2O5 (Li2O•2LiMnO2), by Freire et al. in 2015. When prepared at 800 C, it has been determined that the formula of this compound can be designated more accurately as Li4Mn2O4.5, alternatively Li2O•Li0.667Mn1.333O2, or close thereto. The cubic, disordered Li0.667Mn1.333O2 (or Li0.333Mn0.667O) rock salt component, in which the manganese ions adopt an average oxidation state of 2.5+, transforms to a clearly-defined spinel configuration during electrochemical cycling. The electrochemical activation process during the initial charge reaction appears to include the oxidation of the manganese ions by oxygen released by the Li2O component between 4.5 and 4.6 V. In complete contrast, nickel-substituted electrodes, such as Li2O•2LiMn0.5Ni0.5O2 and Li2O•2LiMn0.475Ni0.475Co0.050O2, in which the manganese ions adopt a tetravalent state, have disordered rock salt components that are electrochemically inactive
Particle-particle interface corrosion of cold sprayed copper in dilute nitric acid solution: Geometry-controlled corrosion mechanism
No full textThe mechanism of particle-particle interface (PPI) corrosion observed in cold sprayed (CS) Cu immersed in dilute HNO3 has been elucidated. PPI corrosion is initiated by the oxide inclusions present along the PPIs. The accelerated corrosion rate at PPIs results from the combined effects of confined geometry and catalytic reactions, which involve the electrochemical dissolution of Cu and reduction of NO3−. Annealing the CS Cu at 600°C coalesces the oxide inclusions, thereby breaking the interconnected oxide inclusion network. As a result, the propagation of PPI corrosion is impeded