Ultrasound coupled with activated persulfate can synergistically degrade aqueous organic contaminants. Here, in situ electron paramagnetic resonance spin trapping was used to compare radicals ...produced by ultrasonically activated persulfate (US-PS) and its individual technologies, ultrasound alone (US) and heat-activated persulfate (PS), with respect to temperature. Radicals were trapped using 5,5-dimethyl-1-pyrroline-N-oxide, DMPO, to form detectable nitroxide adducts. Using initial rates of radical adduct formation, and compared to US and PS, US-PS at 40 and 50 °C resulted in the largest synergistic production of radicals. Radicals generated from US were reasonably consistent from 40 to 70 °C, indicating that temperature had little effect on cavitational bubble collapse over this range. However, synergy indexes calculated from initial rates showed that ultrasonic activation of persulfate at the bubble interface changes with temperature. From these results, we speculate that higher temperatures enhance persulfate uptake into cavitation bubbles via nanodroplet injection. DMPO-OH was the predominant adduct detected for all conditions. However, competition modeling and spin trapping in the presence of nitrobenzene and atrazine probes showed that SO4 •– predominated. Therefore, the DMPO-OH signal is derived from SO4 •– trapping with subsequent DMPO-SO4 – hydrolysis to DMPO-OH. Spin trapping is effective in quantifying total radical adduct formation but limited in measuring primary radical speciation in this case.
We develop a class of models for inference about abundance or density using spatial capture-recapture data from studies based on camera trapping and related methods. The model is a hierarchical model ...composed of two components: a point process model describing the distribution of individuals in space (or their home range centers) and a model describing the observation of individuals in traps. We suppose that trap- and individual-specific capture probabilities are a function of distance between individual home range centers and trap locations. We show that the models can be regarded as generalized linear mixed models, where the individual home range centers are random effects. We adopt a Bayesian framework for inference under these models using a formulation based on data augmentation. We apply the models to camera trapping data on tigers from the Nagarahole Reserve, India, collected over 48 nights in 2006. For this study, 120 camera locations were used, but cameras were only operational at 30 locations during any given sample occasion. Movement of traps is common in many camera-trapping studies and represents an important feature of the observation model that we address explicitly in our application.
Ferroelectric ceramics exhibiting photochromic behavior and reversible luminescence modulation are highly desirable for optoelectronic applications ranging from information storage, displays, ...anti-counterfeiting to photo-switching devices. Herein, Sm3+-doped lead-free 0.85(K0.5Na0.5)NbO3-0.15SrZrO3 (KNN-SZ: Sm3+) transparent ferroelectric ceramic featuring a typical photochromic phenomenon is designed and demonstrated. Upon alternate illumination and thermal stimulus (220 ℃ for 1 min), the ceramic exhibits reversible yellow-gray coloration. Furthermore, a maximum relative reflectivity variation of 29 % and a large luminescence quenching of 65.4 % with superior fatigue resistance were achieved in KNN-SZ: Sm3+. Various in-situ illuminations and thermal treatments in different ambient conditions were carried out to bring insight into the trapping and de-trapping processes involved in photochromic behavior. The KNN-SZ: Sm3+ photochromic ceramics have great prospect in optoelectronic devices expanding the applications of KNN-SZ ceramics into advanced multifunctional materials for devices integration beyond electrical energy storage, electrocaloric and piezoelectric effects.
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•The assumptions of Shannon diversity are violated in many ecological datasets.•Our index handles species differences in detectability and maximum density.•Our index is sensitive to ...population declines.
Camera trapping networks have the potential to monitor wildlife diversity at large scales. However, their efficacy in detecting different species varies, leading to considerable disparities in population density estimates. Furthermore, species of different trophic levels and body sizes naturally occur at different densities, challenging the evenness assumptions inherent in conventional diversity indices. Here we present a novel index: Fractional Richness, which is specifically designed for application in extensive camera trap networks. The index addresses situations where evenness is uninformative, for example in communities characterized by multiple trophic levels, diverse body sizes, variable population densities, or other complications. To determine the effectiveness of our Fractional Richness index, we modeled spatial patterns of Shannon diversity, species richness, and Fractional Richness for two wildlife communities in Wisconsin USA to quantitatively measure which index best reflected ecologically relevant landscape patterns. One community was much more uneven than the other, with detection rates ranging across three orders of magnitude. The more even community could be modeled accurately with both Shannon diversity and Fractional Richness, but the highly uneven community could only be modeled accurately with Fractional Richness. Maximum population density varies by species, and most wildlife survey methods are not equally capable of detecting all species. In communities with both high and low-density species, or when detectability varies, evenness may not be the most informative measure. In these situations, Fractional Richness may be a more suitable index.
Low‐dimensional copper halides having nontoxic elements are attracting increasing attention for their peculiar emission properties. Self‐trapped excitons (STEs) account for their high ...photoluminescence quantum yields (PLQYs) with emission that can stretch across the entire visible spectrum. However, intrinsic factors that influence the formation or loss of the emissive species in low‐dimensional copper halides remain elusive. Here, a comprehensive study on the STE formation dynamics of one‐dimensional CsCu2I3 and zero‐dimensional Cs3Cu2I5 is presented. It is found from STE kinetic analysis that a slower STE formation demonstrated by the 1D structure is not hindered by a potential barrier, but instead related to the number of phonons released in the self‐trapping process. It is further revealed that in 1D CsCu2I3, the non‐radiative recombination of STEs mainly occurs via the intersection between the STE state and the ground state in the configuration coordinate diagram, placing an intrinsic limit on the PLQY at room temperature. These findings show that the STE formation is affected by both the self‐trapping depth and the phonon energy as opposed to a potential barrier in low‐dimensional copper halides. The better understanding of STE formation and recombination processes provide basis for improving design and performance for broadband light emitting devices.
The formation rate of self‐trapped excitons (STEs) is influenced by the trapping depth (Etrap) of the excitons and the phonon energy (Ephonon). The non‐radiative loss of STEs from detrapping back to free‐exciton state is negligible due to the large Etrap. The intersection of STE band and ground state can serve as an non‐radiative loss pathway.
Estimating density is a fundamental objective of many animal population studies. Application of methods for estimating population size from ostensibly closed populations is widespread, but ...ineffective for estimating absolute density because most populations are subject to short-term movements or so-called temporary emigration. This phenomenon invalidates the resulting estimates because the effective sample area is unknown. A number of methods involving the adjustment of estimates based on heuristic considerations are in widespread use. In this paper, a hierarchical model of spatially indexed capture—recapture data is proposed for sampling based on area searches of spatial sample units subject to uniform sampling intensity. The hierarchical model contains explicit models for the distribution of individuals and their movements, in addition to an observation model that is conditional on the location of individuals during sampling. Bayesian analysis of the hierarchical model is achieved by the use of data augmentation, which allows for a straightforward implementation in the freely available software WinBUGS. We present results of a simulation study that was carried out to evaluate the operating characteristics of the Bayesian estimator under variable densities and movement patterns of individuals. An application of the model is presented for survey data on the flat-tailed horned lizard (Phrynosoma mcallii) in Arizona, USA.
A combination of photoemission, atomic force, and scanning tunneling microscopy/spectroscopy measurements shows that excess electrons in the TiO2 anatase (101) surface are trapped at step edges. ...Consequently, steps act as preferred adsorption sites for O2. In density functional theory calculations electrons localize at clean step edges, this tendency is enhanced by O vacancies and hydroxylation. The results show the importance of defects for the wide‐ranging applications of titania.
In step: Step edges on the TiO2 anatase (101) surface act as exclusive charge trapping centers. While the electron trapping is not favorable at (101) terraces, it is possible at the steps. It results in a higher reactivity of the steps towards some adsorbates, as illustrated for the example of O2 adsorption.
We review the literature data published on the topic of CO2 wettability of storage and seal rocks. We first introduce the concept of wettability and explain why it is important in the context of ...carbon geo‐sequestration (CGS) projects, and review how it is measured. This is done to raise awareness of this parameter in the CGS community, which, as we show later on in this text, may have a dramatic impact on structural and residual trapping of CO2. These two trapping mechanisms would be severely and negatively affected in case of CO2‐wet storage and/or seal rock. Overall, at the current state of the art, a substantial amount of work has been completed, and we find that:
Sandstone and limestone, plus pure minerals such as quartz, calcite, feldspar, and mica are strongly water wet in a CO2‐water system.
Oil‐wet limestone, oil‐wet quartz, or coal is intermediate wet or CO2 wet in a CO2‐water system.
The contact angle alone is insufficient for predicting capillary pressures in reservoir or seal rocks.
The current contact angle data have a large uncertainty.
Solid theoretical understanding on a molecular level of rock‐CO2‐brine interactions is currently limited.
In an ideal scenario, all seal and storage rocks in CGS formations are tested for their CO2 wettability.
Achieving representative subsurface conditions (especially in terms of the rock surface) in the laboratory is of key importance but also very challenging.
Key Points:
CO2 wettability of seal and storage rock: summary of state‐of‐the‐art
CO2 wettability of rocks
Impact on residual and structural trapping capacity
Geologic sequestration in sedimentary formations has been identified as a potential technology to prevent climate‐change inducing carbon dioxide (CO2) from being emitted to the atmosphere. To achieve ...safe and effective storage underground, accurate understanding, and predictions of supercritical CO2 (scCO2) behavior in subsurface rock formations is required; including quantifying how much scCO2 is trapped within pore spaces by capillarity (vs. how much remains mobile), and constraining the occurrence of physio‐chemical reactions between scCO2 and the mineral matrix. Experiments where multiple cycles of scCO2 and brine are injected into rock samples have produced conflicting results regarding the consistency of trapping as cycles progress; likely due to differences in mineral content, pressure‐temperature conditions, aqueous chemistry parameters, and experimental setups. We present a new set of experiments, replicating the conditions of a previous study, but with a new experimental design, apparatus, and timeline. We confirm previous results that demonstrated shifts in injection pressure and scCO2 trapping behavior over multiple injection cycles, and we conduct additional analyses to discern the fluid‐fluid macroscopic contact angle, interface mean and Gaussian curvatures, scCO2 interfacial area, and topology of trapped scCO2 ganglia. We also performed lattice‐Boltzmann simulations approximating experimental conditions where solid wettability was systematically altered over multiple injections cycles; trends in scCO2 ganglia characteristics compare well between experiment and simulation. The results indicate that this system undergoes a transition to a “patchy” mixed‐wet state, and we observe that this wettability alteration renders scCO2 more stable in the rock pore space, increasing capillary trapping over four injection cycles.
Key Points
Experimental results from four cycles of CO2 and brine injections into Bentheimer sandstone
X‐ray tomography imaged data exhibit evolution of fluid configuration and wettability state
Transition to “patchy” mixed‐wet state increases residual trapping of CO2
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