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Background: The increased interest in why and how trees die from fire has led to several syntheses of the potential mechanisms of fire-induced tree mortality. However, these generally neglect to consider experimental methods used to simulate fire behaviour conditions. Aims: To describe, evaluate the appropriateness of and provide a historical timeline of the different approaches that have been used to simulate fire behaviour in fire-induced tree mortality studies. Methods: We conducted a historical review of the different actual and fire proxy methods that have been used to further our understanding of fire-induced tree mortality. Key results: Most studies that assess the mechanisms of fire-induced tree mortality in laboratory settings make use of fire proxies instead of real fires and use cut branches instead of live plants. Implications: Further research should assess mechanisms of fire-induced tree mortality using live plants in paired combustion laboratory and landscape fire experiments. We conduct a review of different fire behaviour proxies and real fire methods that have been used to assess the mechanisms of fire-induced mortality. We conclude that further research should assess mechanisms of fire-induced tree mortality using live plants in paired combustion laboratory and landscape fire experiments. [ABSTRACT FROM AUTHOR]

Additions to the popular evaporation rate determination laboratory of alcohol-based hand-rub sanitizers are described here. Significantly, inquiry-driven protocols for formulating hand-rub sanitizers, falling-ball viscometry, and sanitizer efficacy are included. Incorporation of familiar substances ("molecular relevance") enables students to assimilate knowledge and connect to and recognize interrelated disciplines. To stimulate engagement and project ownership, students were given the opportunity to alter sanitizer formulations by varying the amount and molecular weight of the gelling agent. Viscosities were determined using a falling-ball viscometer to integrate physics and fluid dynamics concepts into these experiments. Lastly, to stress microbiological applications and determine the efficacy of their hand sanitizers, students tested the formulated hand sanitizers for qualitative efficacy using agar plating of skin secretions and comparing colonies formed from sanitized versus nonsanitized hands. Chemistry students with diverse interests recognized links across disciplinary boundaries (e.g., increased their awareness of physical properties of hand sanitizers and the relationship of molecular-scale phenomena to these properties). This three-hour laboratory provides an interdisciplinary supplement directly designed for freshman chemistry and engineering chemistry undergraduates and increases integration among biology, chemistry, engineering, and physics.

The benthic sediments in Lake Coeur d Alene, northern Idaho, have been contaminated by metals (primarily Zn, Pb, and Cu) from decades of upstream mining activities. As part of ongoing research on the biogeo-chemical cycling of metals in this area, a diffusive reactive-transport model has been developed to simulate metal transport in the lake sediments. The model includes 1-D inorganic diffusive transport coupled to a biotic reaction network with multiple terminal electron acceptors under redox disequilibrium conditions. Here, the model is applied to evaluate the competing effects of heavy-metal mobilization through biotic reductive dissolution of Fe(III) (hydr)oxides, and immobilization as biogenic sulfide minerals. Results indicate that the relative rates of Fe and sulfate reduction could play an important role in metal transport through the envi-ronment, and that the formation of (bi)sulfide complexes could significantly enhance metal solubility, as well as desorption from Fe hydroxides.

The heterogeneity of the fractured-basalt and interbedded-sediment aquifer along the eastern margin of the Columbia Plateau Regional Aquifer System has presented challenges to resource managers in quantifying recharge and estimating sustainable withdrawals. Previous studies indicated recharge pathways in alluvial sediments atop a mountain–front interface upgradient of the basalt flows. In this sedimentary zone, six seismic stations were deployed for one year to detect velocity changes in low-frequency seismic waves that could be correlated to changes in groundwater recorded by a well transducer near the center of the seismic station network. Waveforms in the 1−5 Hz range were recorded at each station to determine changes in wave velocities between station pairs and correlate these velocity changes to changes in groundwater levels. The velocity–groundwater relation allowed for estimation of daily groundwater levels beneath the seismic station network. Existing hydrogeologic information was used to estimate hydraulic gradients and hydraulic conductivities, which allowed for the calculation of the daily volume of recharge passing beneath the seismic stations and into the confined aquifer system. The daily recharge volumes across the seismic station network were summed for comparison of the total annual recharge calculated from the change in seismic wave velocities (154,660 m3) to a flow model calculation of recharge based on areal precipitation and infiltration (26,250 m3). The 6× greater recharge estimated from the seismic wave velocity changes for this portion of the recharge zone is attributed to preferential pathways of high hydraulic conductivity and greater depth associated with paleochannels beneath the seismic station network. [ABSTRACT FROM AUTHOR]

The mobility of a metal in mining-impacted sediments is determined by the environmental conditions that influence the metal's oxidation state and bonding environment. Coeur d'Alene Lake, USA, has been impacted by legacy mining practices that allowed the hydrologic transport of mining waste to the lakebed, resulting in substantial amounts of redox-sensitive Fe and Mn along with Ag, As, Cd, Cu, Hg, Pb, Sb, and Zn. Future lake conditions may include algal blooms and additional algal detritus at the sediment–water interface, which may alter Fe and Mn forms that can influence their, and other metal(loid)s, mobility during seasonal anoxia. Cores of the lakebed sediments were exposed to anoxic and anoxic + algal detritus conditions for 8 weeks. Sediment samples were collected biweekly for analysis of Fe and Mn oxidation states and bonding environments by synchrotron-based X-ray absorption spectroscopy. Over the 8-week period and at a location 12.5 cm deep in the sediments, anoxic and anoxic + algae conditions produced limited changes in Fe and Mn oxidation states and bonding environments. At a location 2.5 cm below the sediment–water interface, the anoxic condition promoted a relatively stable environment in which Fe and Mn oxidation states and bonding environments did not vary greatly during the experiment. At the 2.5 cm depth, the anoxic + algae condition substantially altered the Mn oxidation state distribution and bonding environment, but this condition did not strongly influence the Fe oxidation state distribution or bonding environment. The anoxic + algae condition increased the presence of Mn3+, produced Mn4+ at select times, altered the Mn bonding environment, and temporarily increased the release of Mn into porewater. The algae influence on sediment and porewater Mn likely occurred because of the increased formation of organo-Mn complexes produced during algae-enhanced enzymatic processes. The lack of influence of algal detritus on sediment and porewater Fe and the formation of soluble organo-Mn complexes may limit the potential increase in the mobility of other metal(loid)s with future lake conditions. [ABSTRACT FROM AUTHOR]

AST-120 is an orally administered adsorbent used to slow the progression of chronic kidney disease (CKD). This was a randomized, open-label, 5-way crossover study to assess the effect of AST-120 [...]

Transport of cholytaurine (C-tau) across single layers of differentiated colonic adenocarcinoma (Caco-2) cells produced on diffusible filter inserts, is saturably and time linearly dependent on Na+. This transport in the apical to the basolateral direction is demonstrated to be 17 times more efficient than that in the reverse direction, and is inhibited by low incubation temperature, metabolic deactivators and unidentified bile acids. The mechanism of transport of bile acids is equivalent to that of ileal brush-border membrane vessicles and isolated ileal enterocytes, thus serving as a tool for the ascertaining of the molecular basis of ileal bile acid transport.