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  1. Abstract

    As the pressures on water resources are ever increasing, the organization of complex disparate data and scientific information to inform the actions to protect and enhance the resilience of freshwater resources is key for sustainable development and implementation of integrated water resource management (IWRM). Methodologies supporting IWRM implementation have largely focused on water management and governance, with less attention to evaluation methods of ecologic, economic, and social conditions. To assist in assessing water resource sustainability, the Integrated Hydro‐Environment Assessment Tool (IHEAT) has been developed to create a framework for different disciplines and interests to engage in structured dialogue. The IHEAT builds on the considerable body of knowledge developed around IWRM and seeks to place this information into a single framework that facilitates the cogeneration of knowledge between managers, stakeholders, and the communities affected by management decisions with the understanding that there is a need to merge expert analysis with traditional knowledge and the lived experience of communities. IHEAT merges the driver‐pressure‐state‐impact‐response (DPSIR) framework, the Millennium Ecosystem Assessment's ecosystem services and human well‐being (HWB) framework, sustainability criteria for water resource systems, and water resources indexes and sets of indicators to better understand spatiotemporal interactions between hydrologic, socioeconomic, and ecologic systems and evaluate impacts of disturbances on ecological goods and services and HWB. IHEAT consists of a Conceptual Template (IHEAT‐CT) which provides a systematic framework for assessing basin conditions and guiding indicator selection as well as an Assessment Interface (IHEAT‐AI) for organizing, processing, and assessing analytical results. The IHEAT‐CT, presented herein, is a rapid screening tool that connects water use directly, or through ecosystem goods and services (EGS), to constituents of HWB. Disturbance Templates for eight pressure types, such as land‐use change, climate change, and population growth, are provided to guide practitioners regarding potential changes to landscape elements in the hydrological cycle, impacts on EGS, and societal implications on HWB. The basin screening results in a summary report card illuminating key freshwater ecosystems, the EGS they provide, and potential responses to drivers and pressures acting on the hydrologic system. This screening provides a common understanding by technical and nontechnical parties and provides the foundation for more complex conceptual models should they be required. An indicator list guides the selection of hydrologic, ecologic, economic, and social analytical methods to support IWRM technical input.

     
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  2. null (Ed.)
  3. DNA strands are polymeric ligands that both protect and tune molecular-sized silver cluster chromophores. We studied single-stranded DNA C4AC4TC3XT4 with X = guanosine and inosine that form a green fluorescent Ag106+ cluster, but these two hosts are distinguished by their binding sites and the brightness of their Ag106+ adducts. The nucleobase subunits in these oligomers collectively coordinate this cluster, and fs time-resolved infrared spectra previously identified one point of contact between the C2–NH2 of the X = guanosine, an interaction that is precluded for inosine. Furthermore, this single nucleobase controls the cluster fluorescence as the X = guanosine complex is ∼2.5× dimmer. We discuss the electronic relaxation in these two complexes using transient absorption spectroscopy in the time window 200 fs–400 µs. Three prominent features emerged: a ground state bleach, an excited state absorption, and a stimulated emission. Stimulated emission at the earliest delay time (200 fs) suggests that the emissive state is populated promptly following photoexcitation. Concurrently, the excited state decays and the ground state recovers, and these changes are ∼2× faster for the X = guanosine compared to the X = inosine cluster, paralleling their brightness difference. In contrast to similar radiative decay rates, the nonradiative decay rate is 7× higher with the X = guanosine vs inosine strand. A minor decay channel via a dark state is discussed. The possible correlation between the nonradiative decay and selective coordination with the X = guanosine/inosine suggests that specific nucleobase subunits within a DNA strand can modulate cluster–ligand interactions and, in turn, cluster brightness. 
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  4. Abstract

    The transport of particles and fluids through multichannel microfluidic networks is influenced by details of the channels. Because channels have micro-scale textures and macro-scale geometries, this transport can differ from the case of ideally smooth channels. Surfaces of real channels have irregular boundary conditions to which streamlines adapt and with which particle interact. In low-Reynolds number flows, particles may experience inertial forces that result in trans-streamline movement and the reorganization of particle distributions. Such transport is intrinsically 3D and an accurate measurement must capture movement in all directions. To measure the effects of non-ideal surface textures on particle transport through complex networks, we developed an extended field-of-view 3D macroscope for high-resolution tracking across large volumes ($$25\,\hbox {mm} \times 25\,\hbox {mm} \times 2\,\hbox {mm}$$25mm×25mm×2mm) and investigated a model multichannel microfluidic network. A topographical profile of the microfluidic surfaces provided lattice Boltzmann simulations with a detailed feature map to precisely reconstruct the experimental environment. Particle distributions from simulations closely reproduced those observed experimentally and both measurements were sensitive to the effects of surface roughness. Under the conditions studied, inertial focusing organized large particles into an annular distribution that limited their transport throughout the network while small particles were transported uniformly to all regions.

     
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