Using photo elicitation to understand first-year student experiences: Student metaphors of life, university and learning

Publishe

Large tunable image-charge effects in single-molecule junctions

The characteristics of molecular electronic devices are critically determined by metal-organic interfaces, which influence the arrangement of the orbital levels that participate in charge transport. Studies on self-assembled monolayers (SAMs) show (molecule-dependent) level shifts as well as transport-gap renormalization, suggesting that polarization effects in the metal substrate play a key role in the level alignment with respect to the metal's Fermi energy. Here, we provide direct evidence for an electrode-induced gap renormalization in single-molecule junctions. We study charge transport in single porphyrin-type molecules using electrically gateable break junctions. In this set-up, the position of the occupied and unoccupied levels can be followed in situ and with simultaneous mechanical control. When increasing the electrode separation, we observe a substantial increase in the transport gap with level shifts as high as several hundreds of meV for displacements of a few \aa ngstroms. Analysis of this large and tunable gap renormalization with image-charge calculations based on atomic charges obtained from density functional theory confirms and clarifies the dominant role of image-charge effects in single-molecule junctions

Rates of sustainable forest harvest depend on rotation length and weathering of soil minerals

Abstract Removals of forest biomass in the northeastern US may intensify over the coming decades due to increased demand for renewable energy. For forests to regenerate successfully following intensified harvests, the nutrients removed from the ecosystem in the harvested biomass (including N, P, Ca, Mg, and K) must be replenished through a combination of plant-available nutrients in the soil rooting zone, atmospheric inputs, weathering of primary minerals, biological N fixation, and fertilizer additions. Few previous studies (especially in North America) have measured soil nutrient pools beyond exchangeable cations, but over the long rotations common in this region, other pools which turn over more slowly are important. We constructed nutrient budgets at the rotation time scale for three harvest intensities and compared these with detailed soil data of exchangeable, organic, and primary mineral stocks of in soils sampled in 15 northern hardwood stands developed on granitic till soils in the White Mountain region of New Hampshire, USA. This comparison can be used to estimate how many times each stand might be harvested without diminishing productivity or requiring fertilization. Under 1990s rates of N deposition, N inputs exceeded removals except in the most intensive management scenario considered. Net losses of Ca, K, Mg, and P per rotation were potentially quite severe, depending on the assumptions used.Biologically accelerated soil weathering may explain the lack of observed deficiencies in regenerating forests of the region. Sites differed widely in the long-term nutrient capital available to support additional removals before encountering limitations (e.g., a fourfold difference in available Ca, and a tenfold difference in weatherable Ca). Intensive short-rotation biomass removal could rapidly deplete soil nutrient capital, but traditional long rotations, even under intensive harvesting, are unlikely to induce nutrient depletion in the 21st century. Weatherable P may ultimately limit biomass production on granitic bedrock (in as few as 6 rotations). Understanding whether and how soil weathering rates respond to nutrient demand will be critical to determining long-term sustainability of repeated intensive harvesting over centuries

Geoscience after IT: Part L. Adjusting the emerging information system to new technology

Coherent development depends on following widely used standards that respect our vast legacy of existing entries in the geoscience record. Middleware ensures that we see a coherent view from our desktops of diverse sources of information. Developments specific to managing the written word, map content, and structured data come together in shared metadata linking topics and information types

Simulation-based model course to demonstrate seafarers' competence for deck officers' discipline

Postprint (published version

Stretchable electronics for artificial skin

Postprint (published version

First-order and multi-order diffractive lens using a device with 8P phase modulation range

Postprint (published version