Fertilizer-Insecticide Mixtures on Corn

Soil fertility and insects are major factors that affect corn yields. The proper kinds and amounts of fertilizers and insecticides when used properly will make corn production more economical on fields where either or both are needed

Ballistic Thermal Rectification in Asymmetric Three-Terminal Mesoscopic Dielectric Systems

By coupling the asymmetric three-terminal mesoscopic dielectric system with a temperature probe, at low temperature, the ballistic heat flux flow through the other two asymmetric terminals in the nonlinear response regime is studied based on the Landauer formulation of transport theory. The thermal rectification is attained at the quantum regime. It is a purely quantum effect and is determined by the dependence of the ratio $\tau_{RC}(\omega)/\tau_{RL}(\omega)$ on $\omega$, the phonon's frequency. Where $\tau_{RC}(\omega)$ and $\tau_{RL}(\omega)$ are respectively the transmission coefficients from two asymmetric terminals to the temperature probe, which are determined by the inelastic scattering of ballistic phonons in the temperature probe. Our results are confirmed by extensive numerical simulations.Comment: 10 pages, 4 figure

Thermopower of a Kondo-correlated quantum dot

The thermopower of a Kondo-correlated gate-defined quantum dot is studied using a current heating technique. In the presence of spin correlations the thermopower shows a clear deviation from the semiclassical Mott relation between thermopower and conductivity. The strong thermopower signal indicates a significant asymmetry in the spectral density of states of the Kondo resonance with respect to the Fermi energies of the reservoirs. The observed behavior can be explained within the framework of an Anderson-impurity model. Keywords: Thermoelectric and thermomagnetic effects, Coulomb blockade, single electron tunneling, Kondo-effect PACS Numbers: 72.20.Pa, 73.23.HkComment: 4 pages, 4 figures, revised version, changed figure

Sequential and co-tunneling behavior in the temperature-dependent thermopower of few-electron quantum dots

We have studied the temperature dependent thermopower of gate-defined, lateral quantum dots in the Coulomb blockade regime using an electron heating technique. The line shape of the thermopower oscillations depends strongly on the contributing tunneling processes. Between 1.5 K and 40 mK a crossover from a pure sawtooth- to an intermitted sawtooth-like line shape is observed. The latter is attributed to the increasing dominance of cotunneling processes in the Coulomb blockade regime at low temperatures.Comment: 4 pages, 4 figures, submitted to Phys. Rev.

Thermopower of Kondo Effect in Single Quantum Dot Systems with Orbital at Finite Temperatures

We investigate the thermopower due to the orbital Kondo effect in a single quantum dot system by means of the noncrossing approximation. It is elucidated how the asymmetry of tunneling resonance due to the orbital Kondo effect affects the thermopower under gate-voltage and magnetic-field control.Comment: 4 pages, 4 figures, proceeding of Second International Symposium on Nanometer-Scale Quantum Physic

Measuring Temperature Gradients over Nanometer Length Scales

When a quantum dot is subjected to a thermal gradient, the temperature of electrons entering the dot can be determined from the dot's thermocurrent if the conductance spectrum and background temperature are known. We demonstrate this technique by measuring the temperature difference across a 15 nm quantum dot embedded in a nanowire. This technique can be used when the dot's energy states are separated by many kT and will enable future quantitative investigations of electron-phonon interaction, nonlinear thermoelectric effects, and the effciency of thermoelectric energy conversion in quantum dots.Comment: 6 pages, 5 figure

The ancient iron mines of Meroe

Ongoing archaeometallurgical research at the Royal City of Meroe and the nearby Meroitic town of Hamadab in Sudan has established the presence of a Kushite iron production tradition spanning over one thousand years. Potentially from as early as the seventh century BC to as late as the sixth century AD, a significant quantity of iron was produced at Meroe, while Hamadab appears to have started producing iron during the latter stages of this time-frame. Previous investigations assumed that the iron ore exploited for use was widely available and easily accessible, close to the ancient city itself. This paper presents the results of archaeological and geological research that has, for the first time, identified ancient iron mining activity in the area. Insights gained into certain aspects of the ore procurement stage of the chaîne opératoire of Meroitic iron production, including the nature of the mined ores and the manner in which this activity was conducted, are presented. Indications as to the organisation of mining activities are also provided. The significant potential of this avenue of research is highlighted and potential future research questions are posed.Qatar-Sudan Archaeology Project grant 037 UCL Qatar core grant British Institute in Eastern Afric

Spin-dependent thermoelectric transport through double quantum dots

We study thermoelectric transport through double quantum dots system with spin-dependent interdot coupling and ferromagnetic electrodes by means of the non-equilibrium Green function in the linear response regime. It is found that the thermoelectric coefficients are strongly dependent on the splitting of interdot coupling, the relative magnetic configurations and the spin polarization of leads. In particular, the thermoelectric efficiency can achieve considerable value in parallel configuration when the effective interdot coupling and tunnel coupling between QDs and the leads for spin-down electrons are small. Moreover, the thermoelectric efficiency increases with the intradot Coulomb interactions increasing and can reach very high value at an appropriate temperature. In the presence of the magnetic field, the spin accumulation in leads strongly suppresses the thermoelectric efficiency and a pure spin thermopower can be obtained.Comment: 5 figure

Anti-oxidant inhibition of hyaluronan fragment-induced inflammatory gene expression

<p>Abstract</p> <p>Background</p> <p>The balance between reactive oxygen species (ROS) and endogenous anti-oxidants is important in maintaining healthy tissues. Excessive ROS states occur in diseases such as ARDS and Idiopathic Pulmonary Fibrosis. Redox imbalance breaks down the extracellular matrix component hyaluronan (HA) into fragments that activate innate immune responses and perpetuate tissue injury. HA fragments, via a TLR and NF-κB pathway, induce inflammatory gene expression in macrophages and epithelial cells. NAC and DMSO are potent anti-oxidants which may help balance excess ROS states.</p> <p>Methods</p> <p>We evaluated the effect of H₂O₂, NAC and DMSO on HA fragment induced inflammatory gene expression in alveolar macrophages and epithelial cells.</p> <p>Results</p> <p>NAC and DMSO inhibit HA fragment-induced expression of TNF-α and KC protein in alveolar and peritoneal macrophages. NAC and DMSO also show a dose dependent inhibition of IP-10 protein expression, but not IL-8 protein, in alveolar epithelial cells. In addition, H₂O₂synergizes with HA fragments to induce inflammatory genes, which are inhibited by NAC. Mechanistically, NAC and DMSO inhibit HA induced gene expression by inhibiting NF-κB activation, but NAC had no influence on HA-fragment-AP-1 mediated gene expression.</p> <p>Conclusion</p> <p>ROS play a central role in a pathophysiologic "vicious cycle" of inflammation: tissue injury generates ROS, which fragment the extracellular matrix HA, which in turn synergize with ROS to activate the innate immune system and further promote ROS, HA fragment generation, inflammation, tissue injury and ultimately fibrosis. The anti-oxidants NAC and DMSO, by inhibiting the HA induced inflammatory gene expression, may help re-balance excessive ROS induced inflammation.</p