Search

Land surface evapotranspiration (ET) is a major source of moisture for the global hydrologic cycle. Though the influence of the land surface is well documented, moisture tracking analyses aimed at quantifying the contribution of the land surface to precipitation have often relied on offline tracking approaches that require simplifying assumptions and can bias results. Additionally, the contribution of the ET components (transpiration (T), canopy evaporation (C), and ground evaporation (E)) individually to precipitation is not well understood, inhibiting our understanding of moisture teleconnections in both the current and future climate. Here, we use the Community Earth System Model version 1.2 with online numerical water tracers to examine the contribution of local and remote land surface ET, including the contribution from each individual ET component, to precipitation across North America. Much of northern and northeastern North America receives up to 80% of summertime precipitation from land surface ET, and over 50% of that moisture originates from transpiration alone. Local moisture recycling constitutes an essential source of precipitation across much of the southern and western regions of North America, suggesting precipitation across the region is sensitive to local land surface conditions, including soil moisture and vegetation state. The reliance on locally recycled moisture is far less pronounced across northern and eastern North America, where remotely sourced moisture, particularly from transpiration, dominates precipitation contributions. The results highlight regions that are especially sensitive to land cover and hydrologic changes in local and upwind areas, providing key insights for drought prediction and water resource management. Plain Language Summary: Evaporation from the land surface is a major source of moisture for the global water cycle. However, the contribution of evaporation components (evaporation from plants, plant surfaces, and soil) individually to precipitation is not well understood, inhibiting our understanding of the water cycle in both current and future climates. Here, we use the Community Earth System Model version 1.2 with water tracers to examine the contribution of local and distant land surface evaporation, including the contribution from each individual evaporation component, to precipitation across North America. Much of northern and northeastern North America receives up to 80% of summertime precipitation from land surface evaporation, and over 50% of that moisture originates from plants alone. Moisture from the local environment constitutes an essential source of precipitation across much of the southern and western regions of North America, suggesting precipitation across the region is sensitive to local land surface conditions, including soil moisture and vegetation. These results identify regions whose precipitation could be particularly sensitive to land cover changes, which is necessary for improved drought prediction and water resource management. Key Points: The land surface is a key source of moisture for precipitation across North America contributing up to 80% of summertime precipitationTranspiration‐sourced precipitation dominates in the north and east while canopy and ground evaporation dominates in the south and westSouthwestern North America relies heavily on locally recycled moisture while the northeast relies primarily on remotely sourced moisture [ABSTRACT FROM AUTHOR]

Land surface evapotranspiration (ET) is a major source of moisture for the global hydrologic cycle. Though the influence of the land surface is well documented, moisture tracking analysis has often relied on offline tracking approaches that require simplifying assumptions and can bias results. Additionally, the contribution of the ET components (transpiration (T), canopy evaporation (C), and ground evaporation (E)) individually to precipitation is not well understood, inhibiting our understanding of moisture teleconnections in both the current and future climate. Here we use the Community Earth System Model version 1.2 with online numerical water tracers to examine the contribution of local and remote land surface ET, including the contribution from each individual ET component, to precipitation across North America. We find the role of the land surface and the individual ET components varies considerably across the continent and across seasons. Much of northern and northeastern North America receives up to 80% of summertime precipitation from land surface ET, and over 50 % of that moisture originates from transpiration alone. Local moisture recycling constitutes an essential source of precipitation across much of the southern and western regions of North America, while remote land surface moisture supplies most of the land-based precipitation across northern and eastern North America. Though the greatest contribution of remotely sourced land ET occurs in the north and east, we find the primary sources of North American land surface moisture shifts seasonally. The results highlight regions that are especially sensitive to land cover and hydrologic changes in local and upwind areas, providing key insights for drought prediction and water resource management. [ABSTRACT FROM AUTHOR]

A new class of non‐equiatomic FeNiCoAlTaB (NCATB) high entropy alloy (HEA) is introduced, which exhibits tunable properties from cryogenic/ambient superelasticity to ultra‐high strength through controlling the nature or type of martensite. In the current NCATB‐HEA alloy system, depending on the size of γ'‐Ni3Al (L12) precipitates, thin‐plate, lenticular, butterfly, and lath‐like martensite can form. When thin‐plate thermoelastic martensite is favored, a superelastic strain of about 0.025 (ambient) and ≈0.01 (cryogenic) is achieved with a high yield stress of ≈800 MPa and a high‐damping effect (10 times higher than Cu–Al–Ni superelastic alloy). While for butterfly and lath‐like martensite dominated NCATB‐HEA, an ultra‐high yield stress of around 1.1 GPa is achieved while no superelasticity is demonstrated. This current alloy system helps to expand the application domain of HEAs, for example, into high‐damping applications, robust actuators, space exploration, and other structural material applications. Multifunctionality in a non‐equiatomic FeNiCoAl‐based high entropy alloy (HEA), NCATB is enabled by γ' size control. The development of γ' size and martensite start (Ms) temperature with aging time for NCATB‐HEA aged at 700 °C shows that the morphology of martensites is closely related to γ' precipitate size resulting from different aging conditions. [ABSTRACT FROM AUTHOR]

Increases in resistance to commonly used antibiotics have been reported globally in isolates from humans, wildlife, and the environment. To date, few studies have examined long-term trends in antibiotic resistance in organisms isolated from marine mammal populations. The objective of this study was to examine temporal trends in resistance to antibiotics among pathogens isolated from common bottlenose dolphins (Tursiops truncatus) between 2003 and 2015. Dolphins were captured and released in the Indian River Lagoon, Florida, an ecosystem with a large coastal human population and significant environmental impacts. Swab samples for microbiology were taken from the blowhole, gastric fluid, and feces and cultured on standard media under aerobic conditions. Isolates were identified using gram stain morphology and growth on selective media. Antibiotic resistance was measured using disc diffusion on Mueller Hinton agar and the Multiple Antibiotic Resistance (MAR) index calculated for each pathogen. A total of 733 isolates was obtained from 171 individual dolphins. The most commonly cultured pathogens included Aeromonas hydrophila, Escherichia coli, Edwardsiella tarda, and Vibrio alginolyticus. The overall prevalence of resistance to at least one antibiotic for the 733 isolates was 88.2%. The MAR index increased significantly between 2003 and 2007 and 2010 and 2015 for Pseudomonas aeruginosa and V. alginolyticus. For all bacterial isolates, resistance to cefotaxime, ceftazidime, and gentamicin increased significantly between sampling periods. This is one of few studies to use the MAR index for bacterial isolates from a marine mammal. The significant increases in resistance for some bacterial species likely reflect shared environmental exposures to antibiotics and transfer of resistance to dolphins from terrestrial sources or from animal or human populations. [ABSTRACT FROM AUTHOR]

Seven equimolar, five-component, metal diborides were fabricated via high-energy ball milling and spark plasma sintering. Six of them, including (Hf0.2Zr0.2Ta0.2Nb0.2Ti0.2)B2, (Hf0.2Zr0.2Ta0.2Mo0.2Ti0.2)B2, (Hf0.2Zr0.2Mo0.2Nb0.2Ti0.2)B2, (Hf0.2Mo0.2Ta0.2Nb0.2Ti0.2)B2, (Mo0.2Zr0.2Ta0.2Nb0.2Ti0.2)B2, and (Hf0.2Zr0.2Ta0.2Cr0.2Ti0.2)B2, possess virtually one solid-solution boride phase of the hexagonal AlB2 structure. Revised Hume-Rothery size-difference factors are used to rationalize the formation of high-entropy solid solutions in these metal diborides. Greater than 92% of the theoretical densities have been generally achieved with largely uniform compositions from nanoscale to microscale. Aberration-corrected scanning transmission electron microscopy (AC STEM), with high-angle annular dark-field and annular bright-field (HAADF and ABF) imaging and nanoscale compositional mapping, has been conducted to confirm the formation of 2-D high-entropy metal layers, separated by rigid 2-D boron nets, without any detectable layered segregation along the c-axis. These materials represent a new type of ultra-high temperature ceramics (UHTCs) as well as a new class of high-entropy materials, which not only exemplify the first high-entropy non-oxide ceramics (borides) fabricated but also possess a unique non-cubic (hexagonal) and layered (quasi-2D) high-entropy crystal structure that markedly differs from all those reported in prior studies. Initial property assessments show that both the hardness and the oxidation resistance of these high-entropy metal diborides are generally higher/better than the average performances of five individual metal diborides made by identical fabrication processing. [ABSTRACT FROM AUTHOR]

We have developed a flow cell that allows culturing adherent cells as well as suspended cells in a stable, homogeneous, and low-shear force environment. The device features continuous medium supply and waste exchange. In this paper, a simple and fast protocol for device design, fabrication, and assembly (sealing) based on a poly(dimethylsiloxane) (PMDS)/glass slide hybrid structure is described. The cell culture system performance was monitored, and the effective shear force inside the culture well was also determined. By manipulating the device dimensions and volumetric flow rate, shear stress was controlled during experiments. Cell adhesion, growth, proliferation, and death over long-term culture periods were observed by microscopy. The growth of both endothelial and suspension cells in this device exhibited comparable characteristics to those of traditional approaches. The low-shear culture device significantly reduced shear stress encountered in microfluidic systems, allowing both adherent and suspended cells to be grown in a simple device.