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Experimental tests of cross-laminated timber (CLT)-concrete composite floor panels were conducted. The tests consisted of linear-elastic tests of square CLT-concrete composite panels with a novel shear connector to determine elastic orthotropic plate properties. After the linear-elastic tests, the panels were subjected to a patch load at the center of the panel and tested to failure. To investigate load transfer across longitudinal joints between adjacent panels, nonuniform bending tests were conducted. Results from the experimentally measured orthotropic plate properties showed that the shear connector increased the bending stiffness in the weak direction of the panel compared to prior test results using conventional shear connectors. The tests to failure exhibited larger differences in behavior between the strong and weak orientations of the specimens, with both showing substantial inelastic behavior prior to failure. Numerical finite element models of the patch-load test showed good agreement with experimental results. Analytical formulas using the obtained orthotropic plate properties did not agree with experimental results for the patch-load at linear scales, suggesting the simplified method is currently not suited for CLT-concrete two-way bending. Load-transfer tests found that the reinforced concrete topping is capable of transferring load across the longitudinal joint of two parallel panels to enable two-way bending of composite timber–concrete floors and that the addition of a plywood spline with closely spaced screws enables a higher degree of force transfer. [ABSTRACT FROM AUTHOR]

Per‐ and polyfluoroalkyl substances (PFAS) are a broad group of persistent organic compounds with vastly differing physicochemical and toxicological properties. Some jurisdictions have proposed to regulate PFAS as a single class to overcome the limitations of regulating such a diverse group on a chemical‐by‐chemical basis. Implications of regulating PFAS as a single class have been discussed for PFAS production and use, but equivalent discussion of implications for managing contaminated sites is largely lacking. This opinion piece summarizes the views of a group of environmental consultants, environmental regulators, land managers, and academics with significant experience in researching or managing PFAS. The group considered that neither a single PFAS class approach nor a chemical‐by‐chemical approach is well suited to managing risks from PFAS in a contaminated site setting, and defining PFAS subgroups would have value. Second, some but not all in the group, hypothesize that PFAS properties that drive fate and transport are those that influence toxicity and bioaccumulation in animals. This may be a valuable observation for future discussions on dividing PFAS into subclasses for contaminated site regulation based on physicochemical properties rather than purely structural definitions. [ABSTRACT FROM AUTHOR]

Due to a change in capital funding formula, many school boards across the Province of Ontario engaged in Accommodation Reviews to rationalize the supply of school capacity. This process led to numerous school closures and raised important policy questions regarding the economic value of a school in terms of its capitalization into property values and, by extension, how the closure of a school might affect local neighborhoods. To explore these questions, this research uses spatial hedonic methods to estimate the implicit value of accessibility to schools in the City of Hamilton, Ontario. Spatial Durbin model results provide evidence of a significant negative correlation between distance to schools and housing prices in the Canadian context. This suggests that accessibility to schools is capitalized into property values and that the closure of a neighborhood school may result in potentially significant losses of economic value in communities. [ABSTRACT FROM AUTHOR]

While the use of cross-laminated timber (CLT) panels for building construction has increased over the last several decades, current standards and existing literature provide limited information regarding the design of CLT diaphragms or the prediction of their deflections when subjected to wind and strong earthquake motions. This paper presents the design and assessment of a CLT diaphragm that was part of a full-scale two-story structure subjected to shake-table testing. An analytical model is proposed for diaphragm deflection accounting for in-plane shear and bending stiffness, as well as the stiffness of various connections. Moreover, a refined numerical modeling strategy is proposed in order to consider phenomena such as panel-to-panel gap closure. Results indicate that the analytical model yields conservative results both in terms of deflections and forces when compared to the numerical model that simulates similar sources of strength and stiffness. The analytical model is suitable for the design of symmetric diaphragms with regular shapes, whereas the numerical model can also be used to model asymmetric diaphragms with irregular shapes. [ABSTRACT FROM AUTHOR]

Mass timber construction has seen a growing interest in North America and worldwide. In the US, code provisions allow mass timber buildings to be up to 82 m tall, but with floor slabs requiring a noncombustible, usually cementitious, topping over mass timber panels (MTPs). Designing the MTP and concrete topping to act compositely can increase the strength and stiffness compared to noncomposite MTP floors. Several connections are available to create composite action between an MTP and a concrete topping, with self-tapping screws being the most widely considered practice. A new test fixture and testing method were developed to characterize connection properties and facilitate the selection of fasteners most suitable for developing composite action. Three conventional self-tapping screws were experimentally investigated at the single-fastener scale. The screws were subjected to withdrawal at 90° and 45° orientations to the interface plane between the MTP and concrete. Withdrawal from both the MTP substrate and concrete topping was investigated. Three MTP materials were tested: cross-laminated timber (CLT) consisting of two different wood species and a mass ply panel (MPP). Results demonstrated that the pullout failure of the screwhead from the concrete was the limiting failure mode. Comparisons were made between the experimental results and analytical models for screw withdrawal to assess the applicability of available models to the different MTPs. These models underestimated the capacity of the tested fasteners for all samples except for the fully threaded screws. [ABSTRACT FROM AUTHOR]

Only a fraction of the total number of per‐ and polyfluoroalkyl substances (PFAS) are monitored on a routine basis using targeted chemical analyses. We report on an approach toward identifying bioactive substances in environmental samples using effect‐directed analysis by combining toxicity testing, targeted chemical analyses, and suspect screening. PFAS compete with the thyroid hormone thyroxin (T4) for binding to its distributor protein transthyretin (TTR). Therefore, a TTR‐binding bioassay was used to prioritize unknown features for chemical identification in a PFAS‐contaminated sediment sample collected downstream of a factory producing PFAS‐coated paper. First, the TTR‐binding potencies of 31 analytical PFAS standards were determined. Potencies varied between PFAS depending on carbon chain length, functional group, and, for precursors to perfluoroalkyl sulfonic acids (PFSA), the size or number of atoms in the group(s) attached to the nitrogen. The most potent PFAS were the seven‐ and eight‐carbon PFSA, perfluoroheptane sulfonic acid (PFHpS) and perfluorooctane sulfonic acid (PFOS), and the eight‐carbon perfluoroalkyl carboxylic acid (PFCA), perfluorooctanoic acid (PFOA), which showed approximately four‐ and five‐times weaker potencies, respectively, compared with the native ligand T4. For some of the other PFAS tested, TTR‐binding potencies were weak or not observed at all. For the environmental sediment sample, not all of the bioactivity observed in the TTR‐binding assay could be assigned to the PFAS quantified using targeted chemical analyses. Therefore, suspect screening was applied to the retention times corresponding to observed TTR binding, and five candidates were identified. Targeted analyses showed that the sediment was dominated by the di‐substituted phosphate ester of N‐ethyl perfluorooctane sulfonamido ethanol (SAmPAP diester), whereas it was not bioactive in the assay. SAmPAP diester has the potential for (bio)transformation into smaller PFAS, including PFOS. Therefore, when it comes to TTR binding, the hazard associated with this substance is likely through (bio)transformation into more potent transformation products. Environ Toxicol Chem 2024;43:245–258. © 2023 The Authors. Environmental Toxicology and Chemistry published by Wiley Periodicals LLC on behalf of SETAC. [ABSTRACT FROM AUTHOR]

The structural performance of four reinforced concrete pile cap specimens anchored by widely used proprietary high-strength threaded bars (HSTBs) and subjected to column uplift loads is investigated. The specimens were full-scale replicas of in-service foundations in terms of geometry, material properties, reinforcement details, and loading conditions. The study also included isolated pullout tests of HSTB anchorages. Two of the specimens were modified by increasing the embedment depth of the column anchor plate to assess effectiveness as a possible retrofit approach. Failure of all specimens was brittle without yielding of embedded reinforcing steel. Moreover, the ultimate pullout capacity of the anchors was not achieved in any of the specimens. ACI 318-19 provisions underestimated the concrete breakout capacity of all specimens and were unable to incorporate the beneficial effects of the column anchor plate modification as it only considered the anchor embedment length and edge distance as critical parameters for calculating strength. [ABSTRACT FROM AUTHOR]

New building code changes enable mass timber panels (MTP), including cross-laminated timber (CLT), to be used in moderate and tall buildings as a floor system, usually with a concrete topping. A floor system of CLT composite with a reinforced concrete topping slab can provide increased stiffness and strength, making the system more advantageous. Present connection methods used to produce composite action within timber-concrete composites (TCC) have limitations when considering constructability or performance. This study presents experimental results from four (4) shear connectors for CLT-concrete composite floor systems, including three developed for this study. The connectors included self-tapping screws (STS) at 45-degrees, a modified lag screw with an integral plate washer that bears on the CLT surface at installation, a steel angle anchored only at the end of the span, and an inverted-T steel section with stem perforations. Different tests were performed on the different connectors including individual fastener tests, push-off group tests, and full-scale one-way bending tests. The push-off group tests showed that the proposed washer-screw exhibited higher stiffness and strength than a conventional STS. The full-scale one-way bending testing showed that the STS specimen exhibited the lowest strength of the alternatives. The inverted-T section exhibited the highest stiffness, while the other three connections had similar stiffness to the STS. [ABSTRACT FROM AUTHOR]

Drinking water can be a major source of poly- and perfluoroalkyl substance (PFAS) exposure for humans. The lack of historic data on PFAS drinking-water concentrations and consumption patterns are a limiting factor for developing estimates of past exposure. Here, in contribution to a community-scale PFAS health effects study near fire training facilities that contaminated a local aquifer with PFASs, we present a novel water-infrastructure, mass-balance mixing model coupled to a non-steady state, single-compartment toxicokinetic model that used Monte Carlo simulations to estimate the start of PFAS exposure in drinking water for individuals within three PFAS-impacted communities in El Paso County, Colorado. Our modeling focused on perfluorohexane sulfonic acid (PFHxS) because median serum PFHxS concentrations in a sample of local residents (n = 213) were twelve times the median observed in the U.S. National Health and Nutrition Examination Survey (2015–2016). Modeling results for study participants were grouped according to their community of residence, revealing a median start of exposure for the town of Fountain of 1998 (25–75% interquartile range [IQR], 1992 to 2010), 2006 (IQR 1995 to 2012) for Security, and 2009 (IQR 1996–2012) for Widefield. Based on the towns' locations relative to an identified hydraulically upgradient PFAS source, the modeled exposure sequencing does not completely align with this conceptual flow model, implying the presence of an additional PFAS source for the groundwater between Widefield and Fountain. [ABSTRACT FROM AUTHOR]

One of the most common cell shape changes driving morphogenesis in diverse animals is the constriction of the apical cell surface. Apical constriction depends on contraction of an actomyosin network in the apical cell cortex, but such actomyosin networks have been shown to undergo continual, conveyor belt-like contractions before the shrinking of an apical surface begins. This finding suggests that apical constriction is not necessarily triggered by the contraction of actomyosin networks, but rather can be triggered by unidentified, temporally-regulated mechanical links between actomyosin and junctions. Here, we used C. elegans gastrulation as a model to seek genes that contribute to such dynamic linkage. We found that α-catenin and β-catenin initially failed to move centripetally with contracting cortical actomyosin networks, suggesting that linkage is regulated between intact cadherin-catenin complexes and actomyosin. We used proteomic and transcriptomic approaches to identify new players, including the candidate linkers AFD-1/afadin and ZYX-1/zyxin, as contributing to C. elegans gastrulation. We found that ZYX-1/zyxin is among a family of LIM domain proteins that have transcripts that become enriched in multiple cells just before they undergo apical constriction. We developed a semi-automated image analysis tool and used it to find that ZYX-1/zyxin contributes to cell-cell junctions' centripetal movement in concert with contracting actomyosin networks. These results identify several new genes that contribute to C. elegans gastrulation, and they identify zyxin as a key protein important for actomyosin networks to effectively pull cell-cell junctions inward during apical constriction. The transcriptional upregulation of ZYX-1/zyxin in specific cells in C. elegans points to one way that developmental patterning spatiotemporally regulates cell biological mechanisms in vivo. Because zyxin and related proteins contribute to membrane-cytoskeleton linkage in other systems, we anticipate that its roles in regulating apical constriction in this manner may be conserved. Author summary: Animals take shape during development in large part by the bending of tissues. Failures in this process are common causes of human birth defects. Such tissue bending is driven primarily by individual cells changing shape: in many examples, one side of a cell shrinks, pulling on junctions that connect the cell to neighboring cells. But the networks that drive one side of a cell to shrink are not always connected to junctions. As a result, focus has turned to understanding how connections between such networks and junctions are dynamically regulated to trigger cell shape change. We sought to identify genes that contribute to these dynamic connections. Here, we describe proteomic and transcriptomic methods that we used to identify proteins that contribute to cell shape change. We developed a new image analysis tool and used it to reveal that loss of one of these genes results in networks moving without efficiently pulling in junctions. Our results identify new molecular players, and they pinpoint a key gene whose products might contribute to dynamically connecting networks to junctions to trigger tissue shape changes in C. elegans and other organisms. [ABSTRACT FROM AUTHOR]

Per- and polyfluoroalkyl substances (PFASs) are frequently found at high concentrations in the subsurface of aqueous film forming foam (AFFF)-impacted sites. Geochemical parameters affect the release of PFASs from source area soils into groundwater but have not been extensively studied for soils that have been historically impacted with AFFF. This study investigated the effects of pH and salt concentrations on release of anionic and zwitterionic PFASs from AFFF-impacted soils in flow-through saturated columns. High pH (10) columns with elevated sodium concentrations had higher cumulative masses eluted of several PFASs compared to pH 3 and pH 7 columns with lower sodium concentrations, likely caused by changes to soil organic matter surface charge. Four PFASs (e.g. 4:2 fluorotelomer sulfonate, perfluorobutane sulfonamido acetic acid) eluted significantly earlier in both pH 3 and pH 10/high NaCl columns compared to pH 7 columns. The results of this study suggest that shifts in pH for soils located at AFFF-impacted sites – particularly raising the pH – may mobilize sorbed PFASs, specifically longer-chain and zwitterionic compounds that are typically strongly sorbed to soil. [ABSTRACT FROM AUTHOR]

The cyclic performance of substandard reinforced concrete (RC) bridge substructures seismically retrofitted using titanium alloy bars (TiABs) is assessed using full-scale experiments and nonlinear numerical models. The retrofit technique uses TiAB ligaments to simply and effectively strengthen columns with inadequate flexural lap splices and provides confinement through hoop action when combined with continuous TiAB spirals. The failure characteristics, flexural ductility, and hysteretic behavior of unretrofitted substandard (i.e., vintage) and TiAB retrofitted columns were evaluated using quasi-static, reversed cyclic tests of full-scale bridge column–footing specimens modeled after the characteristics of highway bridges in Oregon constructed prior to the introduction of seismic design provisions. Foundation rocking was examined and quantified through implementation of a soil subgrade simulant. Experimental results demonstrate improved flexural response and ductility with reduced concrete damage and residual drifts of RC columns when retrofitted with TiAB. The measured responses of the test specimens were used to calibrate three-dimensional (3D), nonlinear, finite-difference models used to investigate the effect of soil–structure interaction (SSI) on the rocking moment capacity for as-built and retrofitted column–footing specimens. The model was then used to perform a parametric study to evaluate retrofit details (flexural strength and stiffness) and soil characteristics (strength and stiffness) and their relationships to engineering demand parameters such as displacement and strength, which indicated that incorporation of SSI will permit the design of more efficient and economical seismic retrofits. [ABSTRACT FROM AUTHOR]

Accessibility indicators are widely used in transportation, urban and healthcare planning, among many other applications. These measures are weighted sums of reachable opportunities from a given origin, conditional on the cost of movement, and are estimates of the potential for spatial interaction. Over time, various proposals have been forwarded to improve their interpretability: one of those methodological additions have been the introduction of competition. In this paper we focus on competition, but first demonstrate how a widely used measure of accessibility with congestion fails to properly match the opportunity-seeking population. We then propose an alternative formulation of accessibility with competition, a measure we call spatial availability. This measure relies on proportional allocation balancing factors (friction of distance and population competition) that are equivalent to imposing a single constraint on conventional gravity-based accessibility. In other words, the proportional allocation of opportunities results in a spatially available opportunities value which is assigned to each origin that, when all origin values are summed, equals the total number of opportunities in the region. We also demonstrate how Two-Stage Floating Catchment Area (2SFCA) methods are equivalent to spatial availability and can be reconceptualized as singly-constrained accessibility. To illustrate the application of spatial availability and compare it to other relevant measures, we use data from the 2016 Transportation Tomorrow Survey of the Greater Golden Horseshoe area in southern Ontario, Canada. Spatial availability is an important contribution since it clarifies the interpretation of accessibility with competition and paves the way for future applications in equity analysis (e.g., spatial mismatch, opportunity benchmarking, policy intervention scenario analysis). [ABSTRACT FROM AUTHOR]

An experimental program consisting of four full-scale specimens was conducted to assess the structural behavior of very large reinforced concrete (RC) pile caps supported on steel pipe piles. The tested specimens replicated the geometry, reinforcement details and placement, material properties, as well as support and loading conditions typical of in-service 1980s vintage pile caps. Prior to testing, three-dimensional (3-D) strut-and-tie models were developed to predict the strength of the specimens and expected failure modes. During tests, widespread reinforcement yielding was observed in all specimens. One specimen failed in one-way shear, two specimens failed in two-way shear, and one specimen did not reach failure before reaching the load capacity of the test setup. Based on the experimental results, the strut-and-tie capacity predictions were highly conservative for all specimens and would have required retrofit of the pile caps to carry the expected column axial loads associated with a potential vertical expansion of the building. The high degree of conservatism is attributed to neglecting the beneficial effects of active confinement in the 3-D structure, especially at the pile locations, that underestimates the available bond strength, thereby minimizing the available tension ties. [ABSTRACT FROM AUTHOR]

Bicycling is an increasingly popular mode of travel in Canadian urban areas, like the Greater Toronto and Hamilton Area (GTHA). While trip origins and destinations can be inferred from travel surveys, data on route choice is often not collected which makes it challenging to capture the attributes of routes travelled by people who cycle. With new algorithms for cycle routing it is now possible to infer routes. Using bicycle trip records from the most recent regional travel survey, a spatial interaction model is developed to investigate the built environment correlates of bicycling flows in Hamilton, Ontario, a mid-sized city part of the GTHA. A feature of the analysis is the use of CycleStreets to compare the distance and time according to different routes inferred between trip zones of origin and destination. In addition, network autocorrelation is accounted for in the estimated models. The most parsimonious model suggests that shortest-path quietest routes that minimize traffic best explain the pattern of bicycle trip flows in Hamilton. Commercial and office locations and points of interest at the zone of origin negatively correlate with the production of trips, while different land uses and the availability of jobs at the zone of destination are trip attractors. The use of a route planner offers a novel approach to modelling and understanding bicycling flows within a city. This may be useful for transportation planners to infer different types of routes that bicyclists may seek out and consider these in travel demand models. [ABSTRACT FROM AUTHOR]

Aqueous film-forming foams (AFFFs) are important sources of per- and polyfluoroalkyl substances (PFASs) in soil, groundwater, and surface water. Soil microorganisms can convert polyfluorinated substances into persistent perfluoroalkyl acids, but the understanding of co-contaminant stimulation or inhibition of PFASs biotransformation is limited. In this study, we investigate how aerobic biotransformation of polyfluorinated substances was affected by common AFFF co-contaminants, such as gasoline aromatics: benzene, toluene, ethylbenzene, and o-xylene (BTEX). We performed aerobic microcosm studies by inoculating AFFF-impacted soil with medium containing 6:2 fluorotelomer thioether amido sulfonate (FtTAoS) and either diethyl glycol monobutyl ether (DGBE), a common AFFF ingredient, or BTEX compounds as the main carbon and energy source. BTEX-amended microcosms produced 4.3–5.3 fold more perfluoroalkyl carboxylates (PFCAs) than DGBE-amended ones, even though both organic carbon sources induced similar 6:2 FtTAoS biotransformation rates. In enrichments of AFFF-impacted solids selecting for BTEX biodegradation, we detected the presence of genes encoding toluene dioxygenase as well as larger abundances of transformation products from thioether oxidation that complement larger quantities of terminal transformation products. Our findings indicate that enrichment of BTEX-degrading microorganisms in the AFFF-impacted soil enhanced the conversion of 6:2 FtTAoS to PFCAs. These results provide insights into the high ratio of PFAAs to precursors at AFFF-impacted sites with history of BTEX bioremediation. [ABSTRACT FROM AUTHOR]

Bench-scale experiments were performed to evaluate poly- and perfluoroalkyl substance (PFAS) desorption from vadose zone soils collected at a site historically impacted with aqueous film-forming foam (AFFF). A sequential dilution batch method was employed to obtain PFAS desorption isotherms from a shallow surface soil [0.03 to 0.9 m below ground surface (bgs)] and from a deep soil (0.9–2.4 m bgs). Results showed that the desorption isotherms were reasonably described by a linear model, and that a fraction of the soil-bound PFAS mass was not readily desorbed (or, non-labile); the recalcitrance of this non-labile fraction was evaluated on a subset of samples and shown to persist for up to 9 months. The non-labile fraction of PFAS mass sorbed to the soil (non-labile PFAS sorbed mass divided by the total PFAS sorbed mass) ranged from 0.17 g g−1 for perfluorohexane sulfonamide in the deep soil to 0.87 g g−1 for 8∶2 fluorotelomer sulfonate in the shallow soil, and generally increased with the PFAS organic carbon:water partitioning coefficient (Koc). The fraction of the PFAS within the non-labile fraction was generally greater in the shallow soil than in the deep soil, likely due to the elevated organic carbon content of the shallow soil. The slopes of the desorption isotherms associated with the readily-desorbable (labile) PFAS fraction for the shallow soil were within the ranges predicted by Koc -based models derived from adsorption data. Overall, results for the soils studied herein suggest that much of the PFAS mass present in the soil likely is not readily available for leaching into infiltrating waters. Such information could provide useful insight for developing PFAS soil cleanup standards. [ABSTRACT FROM AUTHOR]

Around the globe, on‐site wastewater‐treatment systems (OWTSs) are critical for rural communities without access to a municipal sewer system. However, their treatment efficiency does not match that of modern wastewater‐treatment plants. The impact of OWTS discharge on nearby aquatic ecosystems and their resident fish species is poorly understood. In the present study, larval and adult fathead minnows (Pimephales promelas) and adult sunfish (Lepomis macrochirus) were exposed for 21 days to two trace organic contaminant (TOrC) mixtures replicating water chemistry derived from a previous environmental study. Larval fathead minnows were assessed for survival, growth, predator avoidance, and feeding efficiency. Adult fathead minnows and sunfish were assessed for a suite of physiological endpoints (condition indices, vitellogenin, glucose), histological changes, and fecundity. The only observed effect of TOrC mixture exposure on larval fathead minnows was a decrease in feeding efficiency. Effects were mixed in exposed adult fishes, except for male sunfish which realized a significant induction of vitellogenin (p < 0.05). The consequences of TOrC mixture exposure in the present controlled laboratory study match effects observed in wild‐caught sunfish in a corresponding field study. The present study begins to bridge the gap by connecting nonpoint OWTS pollution with biological effects observed in resident lake fish species. Given the effects observed despite the brevity of the laboratory mixture exposure, longer‐term studies are warranted to understand the full impacts of OWTS discharge to nearby aquatic ecosystems. Environ Toxicol Chem 2021;40:3193–3204. © 2021 SETAC. This article has been contributed to by US Government employees and their work is in the public domain in the USA. [ABSTRACT FROM AUTHOR]

The ability of shallow bridge foundations to dissipate earthquake energy via rocking has gained significant attention by bridge engineers owing to recent efforts to quantify the performance of rocking footings. This paper presents a new formulation for estimating the moment capacity of rocking bridge foundations resting on all types of soils under varying saturation and surface flux boundary conditions. The proposed formulation uses the moment capacity equation originally employed for saturated soils, classical effective shear strength parameters, and a representation of the soil–water retention curve (SWRC) to accommodate partially saturated conditions that may commonly exist below the shallow foundations of bridge substructures. A closed-form equation is incorporated in this formulation for the matric suction and effective saturation profiles to directly implement surface flux boundary conditions when analyzing the moment capacity of rocking foundations supported on partially saturated soils. The formulation implements a new method to predict the air entry suction for partially saturated soils, representing a key step towards improving the accuracy of moment capacity. A parametric study is performed to investigate the sensitivity of the moment capacity to primary design variables and various surface flux boundary conditions. The analyses demonstrate that flow conditions have a negligible and strong influence on the moment capacity of coarse- and fine-grained soils, respectively. Predictions from the proposed formulation were compared against two sets of experimental data obtained from large-scale shaking table (on sand) and snap-back (on plastic silt) tests and indicated good agreement with experiments. [ABSTRACT FROM AUTHOR]

Per‐ and polyfluoroalkyl substances (PFAS) are compounds manufactured for use in paints, cleaning agents, fire suppressants, nonstick cookware, food containers, and water‐resistant products. Concerns about PFAS stem from their ubiquitous presence in the environment, persistence, and variable/uncertain bioaccumulation and toxicity. In the present study, 5 perfluoroalkyl acids and one polyfluoroalkyl substance were administered to white‐footed mice (Peromyscus leucopus) to elucidate the kinetics of each chemical over 28 d of exposure. Perfluorooctanoate, perfluorohexane sulfonate (PFHxS), and perfluorobutane sulfonate were administered to male and female mice via drinking water. Perfluorooctane sulfonate, perfluorononanoate, 6:2 fluorotelomer sulfonate, and PFHxS were administered to male and female mice via oral gavage. Blood samples collected after 14 or 21 and 28 d of exposure were analyzed for individual PFAS concentrations via liquid chromatography‐tandem mass spectrometry. In general, a plateau in serum concentration in this toxicity test–relevant timeline depended on interactions between 1) the type of PFAS (i.e., perfluoroalkyl sulfonic acids [PFSAs] vs perfluoroalkyl carboxylic acids [PFCAs] vs polyfluorinated), 2) continuous versus bolus dosing, and 3) to a lesser extent, sex. Specifically, PFCAs were detected at higher concentration in females than males, whereas PFSAs were generally detected at similar levels across sex. An exception occurred when PFHxS yielded higher serum levels in males than females through bolus, but not continuous, dosing. Type of PFAS had the largest impact on serum concentrations, whereas sex had the lowest. As such, future work on the toxicokinetics of PFAS in common ecological receptors would be valuable to further explore these patterns. Environ Toxicol Chem 2021;40:2886–2898. © 2021 SETAC. This article has been contributed to by US Government employees and their work is in the public domain in the USA. [ABSTRACT FROM AUTHOR]

Purpose: We present a novel perfusion phantom for validation of arterial spin labeled (ASL) perfusion MRI methods and protocols. Methods: Impinging jets, driven by a peristaltic pump, were used to achieve perfusion‐like mixing of magnetically labeled inflowing fluid within a perfusion compartment. The phantom was validated by varying pump rates and obtaining ASL‐MRI data at multiple postlabeling delays using a pseudo‐continuous ASL sequence with a 3D stack‐of‐spirals readout. An additional data set was acquired using a pseudo‐continuous ASL sequence with a 2D EPI readout. Phantom sensitivity to pseudo‐continuous ASL labeling efficiency was also tested. Results: Fluid dynamics simulations predicted that maximum mixing would occur near the central axis of the perfusion compartment. Experimentally observed signal changes within this region were reproducible and well fit by the standard Buxton general kinetic model. Simulations and experimental data showed no label outflow from the perfusion chamber and calculated perfusion rates, averaged over the entire phantom volume, agreed with the expected volumetric flow rates provided by the flow pump. Phantom sensitivity to pseudo‐continuous ASL labeling parameters was also demonstrated. Conclusion: Perfusion‐like signal can be simulated using impinging jets to create a well‐mixed compartment. Observed perfusion and transit time values were reproducible and within the physiological range for brain perfusion. This phantom design has a broad range of potential applications in both basic and clinical research involving ASL MRI. [ABSTRACT FROM AUTHOR]

A full-scale 2-story mass timber building was tested on the University of California San Diego Natural Hazards Engineering Research Infrastructure (UCSD-NHERI) uniaxial shake table during the period from June 2017 to September 2017. The main objective of the experimental program was to test the performance of mass timber building designs with different seismic lateral force–resisting systems. The focus of this study is on a building configuration designed using self-centering post-tensioned cross-laminated timber (CLT) rocking walls with U-shaped steel flexural plate energy dissipators. The shake-table tests were designed to subject the building to a series of earthquake ground motions of increasing intensity, ranging from a service-level earthquake to 1.20 times the maximum considered earthquake intensity. Between each ground motion, low-amplitude white-noise excitations were applied to the building, which responded as a quasilinear system. In this paper, two output-only operational modal analysis methods are used to estimate the modal parameters (frequency, damping, and mode shapes) based on acceleration data collected during the white-noise shake-table tests. The correlations of observed damage and repairs performed during the experimental program with changes in estimated modal features are reported. The modal parameters estimated from the testing program are also compared with a linear finite-element model that is used to validate the modal identification results and study the performance of the two system identification methods for CLT rocking structures. [ABSTRACT FROM AUTHOR]

This paper presents the behavior of floor diaphragms of a shake-table experiment of a full-scale 2-story mass-timber building structure. The structure consists of glued-laminated timber beams and columns, and floors and walls were designed and built making use of cross-laminated timber panels. Two different floor systems were designed, where the roof consists of a topped cross-laminated timber (CLT)-concrete composite system, and the floor level consists of untopped CLT panels connected with plywood single-surface splines. The CLT floor systems were designed to remain essentially elastic over the whole series of shake-table tests, which included testing of three lateral force–resisting systems tested at three different seismic intensity levels (service level, design basis, and maximum considered earthquake) for a total of 34 shake-table earthquake tests. Results from the testing indicate that CLT diaphragms designed to remain essentially elastic based on basic principles of structural mechanics and existing test data can achieve desired seismic performance objectives. In addition, sources of overstrength in certain elements of the diaphragm need to be explicitly considered for a holistic diaphragm design. [ABSTRACT FROM AUTHOR]

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Bench-scale experiments were performed to measure and evaluate the desorption kinetics of poly- and perfluoroalkyl substances (PFAS) from a vadose zone soil exposed decades ago to aqueous film-forming foams (AFFFs). Desorption kinetics in the shallow zone (0.03–0.9 m below ground surface) that contained an elevated organic carbon (OC) content, and in an underlying deep zone (0.9–2.4 m below ground surface) that contained a relatively low OC content, were evaluated for a wide range of anionic and zwitterionic compounds. Results showed that, for a given perfluorinated chain length, the head group impacted desorption. For the low-OC deep soil, desorption equilibrium generally occurred rapidly (within 48 h), indicating that mass transfer limitations were minimal. However, for the high-OC shallow soil, less-hydrophobic and short-chained compounds (including C<8 for the perfluorinated carboxylates, and C<7 for the perfluorinated sulfonates) generally did not reach equilibrium within 400 h , whereas longer-chained and more-hydrophobic PFAS appeared to reach equilibrium within 48 h. Kinetic desorption modeling revealed that these observations likely were due to the depletion of shorter-chained PFAS in the rapid equilibrium sorption domain, coupled with their persistence in the kinetically controlled sorption domain. Kinetic modeling also showed that the rate of desorption was proportional to the PFAS aqueous diffusivity, confirming that diffusion limited the rate of release from the soils. Overall, the extent of desorption generally was substantially less than that predicted by published Kocfoc relationships, suggesting that PFAS desorption from field-aged soils may have a less pronounced impact on underlying groundwater than anticipated, particularly for shorter-chained PFAS. [ABSTRACT FROM AUTHOR]

Per- and polyfluoroalkyl substances (PFASs) are today considered important constituents of the continuously growing substance group of persistent contaminants of emerging environmental concern (PCEC). Here, we report for the first time the concentrations of 12 relevant PFASs in 28 marine water samples from the Saudi Arabian coastal waters of the Red Sea. The sum levels of 12 PFASs (Σ12 PFAS) in surface seawater ranged from −1. For the reference background site of this study, Σ12 PFAS levels ranged from

Designing structures resistant to tsunami-like flood flow impacts is contingent on the ability to accurately predict dynamic loading effects on building components. To characterize these effects, two metal building cladding subassembly test specimens, designed for Risk Category II and Category IV wind loading, were experimentally subjected to surges and bores with various wave height and initial water levels. The results reveal that maximum structural responses, quantified by curvatures and displacements, occur after initial wave impact, as splash up on the structure subsides. Furthermore, consistent pressure–time histories between specimens in equivalent flow conditions, despite significantly different strains and displacements, suggest structural flexibility does not influence which wave forcing produces the maximum structural response. Lastly, structural analysis of the specimens, based on measured pressures at maximum strain conditions, reveals that loading conditions ranged between hydrostatic and hydrodynamic depending on the initial flooding conditions. With these findings, a method to predict pressure magnitude and distribution on the cladding at the time of maximum structural response for tsunami-like flood flow impacts is proposed. [ABSTRACT FROM AUTHOR]

Aqueous film-forming foams (AFFFs) are complex per- and polyfluoroalkyl substance (PFAS)-containing mixtures used extensively as fire suppressants. AFFF-impacted groundwater and surface water have contaminated drinking water with PFASs in many communities, raising concerns about health effects from drinking water exposures. As individual PFASs have been identified as immune hazards, the immunotoxicity of complex PFAS mixtures is also a concern. Adult female and male C57BL/6 mice were given a commercial AFFF formulation for 10 days via gavage; administered dose was based on combined content of perfluorooctanoate (PFOA) and perfluorooctane sulfonate (PFOS) measured in the formulation (0, 1.88, 3.75, 7.5, or 10 mg PFOS+PFOA/kg body weight). A PFOA positive control of 7.5 mg/kg body weight was also given. Compared with the 0 mg/kg group, the following changes were noted: Body weights of males exposed to 7.5 and 10 mg PFOS+PFOA/kg were reduced by 15%, on average; female body weights did not differ. Average relative liver weights were increased 50%–200% in males and 37.5%–193% in females and liver peroxisome proliferation was increased 2- to 12-fold in all doses of both sexes. Antigen-specific antibody production was suppressed, on average, by 13% in males and by 12.4% in females across all doses. Spleen cellularity and lymphocyte subpopulations did not differ by dose for either sex. Our data indicate that though this complex PFAS mixture contained fairly low PFOA content, it induced changes in C57BL/6 mice similar to changes induced by PFOA alone, likely due to the presence of PFOS and many other PFASs. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Polytechnic is the property of Journal of Polytechnic and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The Atlantic Forest is the second most diverse forest system in South America, and only a fraction of its original distribution remains. In this study, we aim to use robust datasets of small mammals along the entire forest system to disentangle the main drivers for diversity along this gradient. More specifically, we aim to disentangle whether deforestation (recent), biogeographical variables, including 19 bioclimatic variables (historic), or historical trapping bias best describe patterns of taxonomic, functional, and phylogenetic diversities using small mammal assembles, from northeastern Brazil to eastern Paraguay. For that, we applied regression tree analyses to determine what environmental variables best describe each of the dimensions of diversity. Additionally, we implemented polynomial regression to test nonlinear relationships between biodiversity metrics and patch size. We found that patterns of overall taxonomic, functional, and phylogenetic diversities; rodent taxonomic diversity; and marsupial functional diversity were better explained by temperature variables. Meanwhile, marsupial taxonomic and phylogenetic diversities, and rodent functional and phylogenetic diversities were best explained by precipitation variables. Furthermore, patch area, trapping, and latitude were never the best descriptors for any of the diversity dimensions. Although all dimensions of biodiversity are correlated, they have unique information and should be considered individually to better understand biodiversity and inform conservation strategies. We found that fragmentation is impactful at a local scale and becomes less important at a biogeographical scale. Therefore, climatic variables drove biogeographical faunal patterns for all clades, probably reflecting important historical assembly process at large spatial scales. [ABSTRACT FROM AUTHOR]

This article cites a study on women employees who are in part-time employment. The characterization of work-family balance implies that, although part-time work by definition reduces time spent in the work role, the level of demands at home and at work ultimately will shape the psychological experience of balance and the meanings individuals attach to their participation in the work-family system. Individuals who have difficulty balancing work and family may experience problems in two major areas. First, they may experience time management difficulties and find it hard to work out the logistics of both work and family demands. Second, they may perceive high levels of work-family conflict as a form of interrole conflict in which pressures from the work and family domains are in some respects mutually incompatible. This research suggests that although part-time work may facilitate the logistics of time management for women in career and earner positions, the overall perception of work-family conflict may be a function of the specific job context. Women in earner positions appeared to derive far greater benefit through part-time schedules than did women in careers.

Produced water (PW) from oil and gas operations is considered a potential resource for food crop irrigation because of increasing water scarcity in dryland agriculture. However, efforts to employ PW for agriculture have been met with limited success. A greenhouse study was performed to evaluate the effects of PW on physiological and morphological traits of spring wheat (Triticum aestivum). Plants were irrigated with water treatments containing 10 and 50% PW (PW10 and PW50, respectively) and compared to a matching 50% salinity (NaCl50) and 100% tap water controls. Compared to controls, plants watered with PW10 and PW50 exhibited developmental arrest and reductions in aboveground and belowground biomass, photosynthetic efficiency, and reproductive growth. Decreases in grain yield ranged from 70 to 100% in plants irrigated with PW compared to the tap water control. Importantly, the PW10 and NaCl50 treatments were comparable for morphophysiological effects, even though NaCl50 contained 5 times the total dissolved solids, suggesting that constituents other than NaCl in PW contributed to plant stress. These findings indicate that despite discharge and reuse requirements focused on total dissolved solids, salinity stress may not be the primary factor affecting crop health. The results of the present study are informative for developing guidelines for the use of PW in agriculture to ensure minimal effects on crop morphology and physiology. Environ Toxicol Chem 2019;38:1756–1769. © 2019 SETAC [ABSTRACT FROM AUTHOR]

Floating Catchment Area (FCA) methods are a popular tool to investigate accessibility to public facilities, in particular health care services. FCA approaches are attractive because, unlike other accessibility measures, they take into account the potential for congestion of facilities. This is done by 1) considering the population within the catchment area of a facility to calculate a variable that measures level of service, and then 2) aggregating the level of service by population centers subject to catchment area constraints. In this paper we discuss an effect of FCA approaches, an artifact that we term demand and level of service inflation. These artifacts are present in previous implementations of FCA methods. We argue that inflation makes interpretation of estimates of accessibility difficult, which has possible deleterious consequences for decision making. Next, we propose a simple and intuitive approach to proportionally allocate demandand and level of service in FCA calculations. The approach is based on a standardization of the impedance matrix, similar to approaches popular in the spatial statistics and econometrics literature. The result is a more intiuitive measure of accessibility that 1) provides a local version of the provider-to-population ratio; and 2) preserves the level of demand and the level of supply in a system. We illustrate the relevant issues with some examples, and then empirically by means of a case study of accessibility to family physicians in the Hamilton Census Metropolitan Area (CMA), in Ontario, Canada. Results indicate that demand and supply inflation/deflation affect the interpretation of accessibility analysis using existing FCA methods, and that the proposed adjustment can lead to more intuitive results. [ABSTRACT FROM AUTHOR]

Copyright of SDU Journal of Engineering Sciences & Design / Mühendislik Bilimleri ve Tasarım Dergisi is the property of Journal of Engineering Sciences & Design and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

A model of the relationships among executive support systems (ESS), learning, and performance is developed. This model describes the impact of ESS on perceptions of competitive performance when viewed from a learning perspective. The model proposes two types of learning: mental-model maintenance, in which new information fits into existing mental models and confirms them; and mental-model building, in which mental models are changed to accommodate new information. The results of a survey of seventy-three executives support the view that the success of ESS may be contingent upon the type of executive learning they engender. The research found that perceptions of competitive performance resulting from ESS use are strongly related to mental-model building, but found no link between competitive performance and mental-model maintenance. Hence, it seems that ESS can and do foster executive learning. Nevertheless, organizations that embark on ESS development on the basis of promised gains in competitive performance should proceed cautiously. The presence of analysis capability seems to be the best differentiation between mental-model maintenance and mental-model building, leading to a consideration of behaviour vis-à-vis the ESS as a predictor of learning. Without mental-model building, competitive performance gains seem unlikely. In addition, companies should be leery of systems that are justified on the basis of improved technical quality. [ABSTRACT FROM AUTHOR]

The influence of prior experience on personal computer utilization was examined through an extension of a conceptual model developed and tested previously. Respondents were classified on the basis of their self-reported skill level and length of time having used personal computers. Three competing ways of modeling the influence of experience were tested: (1) a direct influence, (2) an indirect influence through six distinct attitude and belief components, and (3) a moderating influence on the relations between the attitude/belief components and utilization. The results suggested that experience influenced utilization directly, that indirect influences were present but less pronounced, and that the moderating influence of experience on the relations between five of six antecedent constructs and utilization was generally quite strong. For researchers, the implications are that prior experience with an information technology (IT) is an important factor to include when developing, testing, or applying models of IT adoption and use. For practitioners, the results highlight the importance of emphasizing applicability of the information technology to the current job and professional development early in the adoption process, with more emphasis on future benefits as experience is gained. [ABSTRACT FROM AUTHOR]

This study investigated the personality characteristics, leadership behaviors, and influence tactics of champions of technological innovations. Analyses of questionnaires and interview transcripts of twenty-five matched pairs of champions and nonchampions revealed that champions reported using transformational leader behaviors to a significantly greater extent than did nonchampions. Champions exhibited higher risk taking and innovativeness, initiated more influence attempts, and used a greater variety of influence tactics than nonchampions. Regression analysis of a model of champion emergence, relating personality characteristics, transformational leader behaviors, and influence tactics, showed that champions were significantly higher than nonchampions on all paths in the model. [ABSTRACT FROM AUTHOR]

Despite decades of research, it is unclear under which circumstances travel is most onerous. While studies have found that some individuals derive positive utility from aspects of commuting, others have shown that traffic congestion can entail important time, monetary, and mental stress costs. Moreover, responses to traffic congestion-related stressors differs by individual characteristics. In response, this research captures how exposure to traffic congestion events, the duration of this exposure, and individual trait susceptibility to congestion affect the utility of commuting. Working through the lens of individual satisfaction with the duration of their commute, we show that not every minute of travel is valued the same by car commuters in Canadian cities. Results suggest a complex relationship between travel time, congestion, and individual predisposition to congestion-related stress. While improvements in travel time matter for increasing commute satisfaction, it is reductions in travel in congested conditions that matter most, particularly among those susceptible to congestion-related stressors. [ABSTRACT FROM AUTHOR]

Rapid transit projects that increase accessibility should result in a localised land value uplift (LVU) benefit for locations near stations. A rich history of research has tested this hypothesis, generally operationalising transit accessibility by proxy through distance from a transit station. However, a growing body of research has also demonstrated LVU effects from transit-oriented development (TOD) as individuals sort themselves into locations that best match their preferences and willingness to pay. Considering the interdependence of transportation and land use in the urban system, we argue that these benefits create a spatial bundle of TOD goods around transit stations and hypothesise that households are willing to pay a premium for locations in more transit-oriented station catchment areas. Utilising latent class analysis, we quantify station area TOD submarkets. Next, interactions between these submarkets and station proximity in spatial hedonic regressions reveal that TOD is capitalised into land values in Toronto, though the maximum amount and spatial impact area of this capitalisation differs by TOD context. [ABSTRACT FROM AUTHOR]