RESUMO
This paper describes a geostatistical approach to model and visualize the space-time distribution of groundwater contaminants. It is illustrated using data from one of the world's largest plume of trichloroethylene (TCE) contamination, extending over 23 km2, which has polluted drinking water wells in northern Michigan. A total of 613 TCE concentrations were recorded at 36 wells between May 2003 and October 2018. To account for the non-stationarity of the spatial covariance, the data were first projected in a new space using multidimensional scaling. During this spatial deformation the domain is stretched in regions of relatively lower spatial correlation (i.e., higher spatial dispersion), while being contracted in regions of higher spatial correlation. The range of temporal autocorrelation is 43 months, while the spatial range is 11 km. The sample semivariogram was fitted using three different types of non-separable space-time models, and their prediction performance was compared using cross-validation. The sum-metric and product-sum semivariogram models performed equally well, with a mean absolute error of prediction corresponding to 23% of the mean TCE concentration. The observations were then interpolated every 6 months to the nodes of a 150 m spacing grid covering the study area and results were visualized using a three-dimensional space-time cube. This display highlights how TCE concentrations increased over time in the northern part of the study area, as the plume is flowing to the so-called Chain of Lakes.
RESUMO
The conducting polymer poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) offers superior advantages in electronics due to its remarkable combination of high electrical conductivity, excellent biocompatibility, and mechanical flexibility, making it an ideal material among electronic skin, health monitoring, and energy harvesting and storage. Nevertheless, pristine PEDOT:PSS films exhibit limitations in terms of both low conductivity and stretchability; while, conventional processing techniques cannot enhance these properties simultaneously, facing the dilemma that highly conductive interconnected PEDOT:PSS domains are susceptible to tensile strain. Via modifying PEDOT:PSS with ionic liquids (ILs), not only a synergistic enhancement of the electrical and mechanical properties can be achieved but also the requirements for the printable bioelectronic are satisfied. In this comprehensive review, the task of providing a thorough examination of the mechanisms and applications of ILs as modifiers for PEDOT:PSS is undertaken. First, the theoretical mechanisms governing the interactions between ILs and PEDOT:PSS are discussed in detail. Then, the enhanced properties and the elucidation of the underlying mechanisms achieved through the incorporation of ILs are reviewed. Next, specific applications of ILs-modified PEDOT:PSS relevant to bioelectronic devices are presented. Last, there is a concise summary and a discussion regarding the opportunities and challenges in this exciting field.
RESUMO
The practical application of the Li metal anode (LMA) is hindered by its low coulombic efficiency and dendrite formation. Although solid-state electrolytes hold promise as ideal partners for LMA, their effectiveness is limited by the poor workability and ionic conductivity. Herein, a modified separator combining the rapid Li+ transport of a liquid electrolyte and the interfacial stability of a solid-state electrolyte is explored to realize stable cycling of the LMA. A conformal nanolayer of LiPON is coated on a polypropylene separator by a scalable magnetron sputtering method, which is compatible with current Li-ion battery production lines and promising for the practical applications. The resulting LMA-electrolyte/separator interface is Li+ -conductive, electron-insulating, mechanically and chemically stable. Consequently, Li|Li cells maintain stable dendrite-free cycling with overpotentials of 10 and 40 mV over 2000 h at 1 and 5 mA cm-2 , respectively. Additionally, the Li|LiFePO4 full cells achieve a capacity retention of 92% after 550 cycles, confirming its application potential.
