236 research outputs found
Two day disturbances in the tropical western Pacific
Fall 1995.Bibliography: pages 63-65.Sponsored by the National Oceanic and Atmospheric Administration NA37RJ0202
Differential influence of components resulting from atmospheric-pressure plasma on integrin expression of human HaCaT keratinocytes
Adequate chronic wound healing is a major problem in medicine. A new solution might be non-thermal atmospheric-pressure plasma effectively inactivating microorganisms and influencing cells in wound healing. Plasma components as, for example, radicals can affect cells differently. HaCaT keratinocytes were treated with Dielectric Barrier Discharge plasma (DBD/air, DBD/argon), ozone or hydrogen peroxide to find the components responsible for changes in integrin expression, intracellular ROS formation or apoptosis induction. Dependent on plasma treatment time reduction of recovered cells was observed with no increase of apoptotic cells, but breakdown of mitochondrial membrane potential. DBD/air plasma increased integrins and intracellular ROS. DBD/argon caused minor changes. About 100 ppm ozone did not influence integrins. Hydrogen peroxide caused similar effects compared to DBD/air plasma. In conclusion, effects depended on working gas and exposure time to plasma. Short treatment cycles did neither change integrins nor induce apoptosis or ROS. Longer treatments changed integrins as important for influencing wound healing. Plasma effects on integrins are rather attributed to induction of other ROS than to generation of ozone. Changes of integrins by plasma may provide new solutions of improving wound healing, however, conditions are needed which allow initiating the relevant influence on integrins without being cytotoxic to cells
Using geospatial tools to optimize cassava agronomy trials in Nigeria and Tanzania
Cassava (Manihot esculenta) is an important staple crop for over half a billion people in Africa yet current yield at farmers’ field is only 20% of the potential yield. The African Cassava Agronomy Initiative (ACAI) project is initiated to mitigate the yield gap through developing site-specific recommendations based on a demand-driven approach. The project responds to specific agronomy-related needs of partners already engaged in cassava dissemination and value chain activities in Nigeria and Tanzania. ACAI is developing site-specific recommendation, where processing geospatial information related to climate, soil and remote sensing data is crucial. We are using spatial multivariate analysis to delineate our partners’ operational area into homogeneous clusters to ensure the representativeness of trial sites and optimize the number of trial sites for maximum operational efficiency
Building the ACS Exams Anchoring Concept Content Map for Undergraduate Chemistry
The ability to coherently assess content knowledge throughout an entire undergraduate career represents a significant advantage for programmatic assessment strategies. Chemistry, as a discipline, has an unusual tool in this regard because of the nationally standardized exams from the ACS Exams Institute. These exams are norm-referenced and allow chemistry departments to make comparisons between the performance of their own students relative to national samples; however, currently there appears to be no systematic means for noting students’ content knowledge growth over a four-year degree. The Exams Institute is undertaking the task of organizing content along an anchoring concept or “big ideas” framework to facilitate this type of analysis
Large Scale Synthesis of Nanostructured Carbon Ti4O7 Hollow Particles as Efficient Sulfur Host Materials for Multilayer Lithium Sulfur Pouch Cells
Applications of advanced cathode materials with well designed chemical components and or optimized nanostructures promoting the sulfur redox kinetics and suppressing the shuttle effect of polysulfides are highly valued. However, in the case of actual lithium sulfur Li amp; 8722;S batteries under practical working conditions, one long term obstacle still exists, which is mainly due to the difficulties in massive synthesis of such nanomaterials with low cost and ease of control on the nanostructure. Herein, we develop a facile synthesis of carbon coated Ti4O7 hollow nanoparticles C amp; 8722;Ti4O7 using spherical polymer electrolyte brush as soft template, which is scalable via utilizing a minipilot reactor. The C amp; 8722;Ti4O7 hollow nanoparticles provide strong chemical adsorption to polysulfides through the large polar surface and additional physical confinement by rich micro amp; mesopores and have successfully been employed as an efficient sulfur host for multilayer pouch cells. Besides, the sluggish kinetics of the sulfur and lithium sulfide redox mechanism can be improved by the highly conductive Ti4O7 via catalyzation of the conversion of polysulfides. Consequently, the C amp; 8722;Ti4O7 based pouch cell endows a high discharge capacity of 1003 amp; 8197;mAh amp; 8201;g amp; 8722;1 at 0.05 amp; 8197;C, a high capacity retention of 83.7 amp; 8201; after 100 amp; 8197;cycles at 0.1 amp; 8197;C, and a high Coulombic efficiency of 97.5 amp; 8201; at the 100th cycle. This work proposes an effective approach to transfer the synthesis of hollow Ti4O7 nanoparticles from lab to large scale production, paving the way to explore a wide range of advanced nanomaterials for multilayer Li amp; 8722;S pouch cell
Monolithic Perovskite Silicon Tandem Solar Cells Fabricated Using Industrial p Type Polycrystalline Silicon on Oxide Passivated Emitter and Rear Cell Silicon Bottom Cell Technology
Combining a perovskite top cell with a conventional passivated emitter and rear cell PERC silicon bottom cell in a monolithically integrated tandem device is an economically attractive solution to boost the power conversion efficiency PCE of silicon single junction technology. Proof of concept perovskite silicon tandem solar cells using high temperature stable bottom cells featuring a polycrystalline silicon on oxide POLO front junction and a PERC type passivated rear side with local aluminum p contacts are reported. For this PERC POLO cell, a process flow that is compatible with industrial, mainstream PERC technology is implemented. Top and bottom cells are connected via a tin doped indium oxide recombination layer. The recombination layer formation on the POLO front junction of the bottom cell is optimized by postdeposition annealing and mitigation of sputter damage. The perovskite top cell is monolithically integrated in a p amp; 8722;i amp; 8722;n junction device architecture. Proof of concept tandem cells demonstrate a PCE of up to 21.3 . Based on the experimental findings and supporting optical simulations, major performance enhancements by process and layer optimization are identified and a PCE potential of 29.5 for these perovskite silicon tandem solar cells with PERC like bottom cell technology is estimate
Coastal Upwelling Supplies Oxygen-Depleted Water to the Columbia River Estuary
Low dissolved oxygen (DO) is a common feature of many estuarine and shallow-water
environments, and is often attributed to anthropogenic nutrient enrichment from
terrestrial-fluvial pathways. However, recent events in the U.S. Pacific
Northwest have highlighted that wind-forced upwelling can cause naturally
occurring low DO water to move onto the continental shelf, leading to
mortalities of benthic fish and invertebrates. Coastal estuaries in the Pacific
Northwest are strongly linked to ocean forcings, and here we report observations
on the spatial and temporal patterns of oxygen concentration in the Columbia
River estuary. Hydrographic measurements were made from transect (spatial
survey) or anchor station (temporal survey) deployments over a variety of wind
stresses and tidal states during the upwelling seasons of 2006 through 2008.
During this period, biologically stressful levels of dissolved oxygen were
observed to enter the Columbia River estuary from oceanic sources, with minimum
values close to the hypoxic threshold of 2.0 mg L−1. Riverine
water was consistently normoxic. Upwelling wind stress controlled the timing and
magnitude of low DO events, while tidal-modulated estuarine circulation patterns
influenced the spatial extent and duration of exposure to low DO water. Strong
upwelling during neap tides produced the largest impact on the estuary. The
observed oxygen concentrations likely had deleterious behavioral and
physiological consequences for migrating juvenile salmon and benthic crabs.
Based on a wind-forced supply mechanism, low DO events are probably common to
the Columbia River and other regional estuaries and if conditions on the shelf
deteriorate further, as observations and models predict, Pacific Northwest
estuarine habitats could experience a decrease in environmental quality
Ten Years of Pathway Analysis: Current Approaches and Outstanding Challenges
Pathway analysis has become the first choice for gaining insight into the underlying biology of differentially expressed genes and proteins, as it reduces complexity and has increased explanatory power. We discuss the evolution of knowledge base–driven pathway analysis over its first decade, distinctly divided into three generations. We also discuss the limitations that are specific to each generation, and how they are addressed by successive generations of methods. We identify a number of annotation challenges that must be addressed to enable development of the next generation of pathway analysis methods. Furthermore, we identify a number of methodological challenges that the next generation of methods must tackle to take advantage of the technological advances in genomics and proteomics in order to improve specificity, sensitivity, and relevance of pathway analysis
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