Nitrogen Management Related to Groundwater Quality in Minnesota

ABSTRACT-Minnesota ranks fifth in overall fertilizer nitrogen (FN) use. Nitrogen is essential for crop production; however, there are concerns about this use relative to profitability and potential impacts on groundwater. There are many sources and sinks of nitrogen in ecosystems. The impact of agricultural management practices on groundwater requires that all sources and fates be considered before FN rates are determined. Research is underway to evaluate relationships between FN application for continuous com and movement of nitrate through soil profiles. Growers making N management decisions have to be able to evaluate the complex nature of N in the environment when they determine their crop needs. Computer software is under development to provide this information on a site specific basis

Setup of an 8 keV laboratory transmission x-ray microscope

This article presents a concept and the first results for the setup of an 8keV laboratory transmission x-ray microscope with a polycapillary optic as condenser at the BliX in Berlin. The incentive of building such a microscope is that the penetration depth for hard x-rays is much higher than in the soft x-ray range, e.g. The water window. Therefore, it is possible to investigate even dense materials such as metal compounds, bones or geological samples. The future aim is to achieve a spatial resolution better than 200 nm

Using the soil nitrate test for corn in Minnesota

1 online resource (PDF, 4 pages)This archival publication may not reflect current scientific knowledge or recommendations. Current information available from the University of Minnesota Extension: https://www.extension.umn.edu

Excitonic photoluminescence in symmetric coupled double quantum wells subject to an external electric field

The effect of an external electric field F on the excitonic photoluminescence (PL) spectra of a symmetric coupled double quantum well (DQW) is investigated both theoretically and experimentally. We show that the variational method in a two-particle electron-hole wave function approximation gives a good agreement with measurements of PL on a narrow DQW in a wide interval of F including flat-band regime. The experimental data are presented for an MBE-grown DQW consisting of two 5 nm wide GaAs wells, separated by a 4 monolayers (MLs) wide pure AlAs central barrier, and sandwiched between Ga_{0.7}Al_{0.3}As layers. The bias voltage is applied along the growth direction. Spatially direct and indirect excitonic transitions are identified, and the radius of the exciton and squeezing of the exciton in the growth direction are evaluated variationally. The excitonic binding energies, recombination energies, oscillator strengths, and relative intensities of the transitions as functions of the applied field are calculated. Our analysis demonstrates that this simple model is applicable in case of narrow DQWs not just for a qualitative description of the PL peak positions but also for the estimation of their individual shapes and intensities.Comment: 5 pages, 4 figures (accepted in Phys. Rev. B

Setup of an 8 keV laboratory transmission x-ray microscope

This article presents a concept and the first results for the setup of an 8keV laboratory transmission x-ray microscope with a polycapillary optic as condenser at the BliX in Berlin. The incentive of building such a microscope is that the penetration depth for hard x-rays is much higher than in the soft x-ray range, e.g. the water window. Therefore, it is possible to investigate even dense materials such as metal compounds, bones or geological samples. The future aim is to achieve a spatial resolution better than 200 nm

A multipurpose experimental facility for advanced X-ray Spectrometry applications

Ponencia presentada en la European Conference on X-Ray Spectrometry (EXRS). 2014Motivation, Ultra High Vacuum Chamber (UHVC) project: To support/enhance the training of scientists/engineers from developing countries in the operation of synchrotron radiation instrumentation; To provide beam time access for R&D projects and hands-on training in SR-XRS based techniques; To promote networking and knowledge sharing; To increase the quality and the competitiveness of the developing countries to apply beam time proposals at SR facilities; To contribute in the further development of XRS techniques in applications with socioeconomicalrelevance (characterization of energy storage/conversion materials, environmental, biological and biomedical applications)Fil: Leani, Juan José. Universidad Nacional de Córdoba. Facultad de Matemática, Astronomía y Física; Argentina.Fil: Leani, Juan José. Nuclear Science and Instrumentation Laboratory, IAEA Laboratories; Austria.Física Atómica, Molecular y Química (física de átomos y moléculas incluyendo colisión, interacción con radiación, resonancia magnética, Moessbauer Efecto.

A monolithically integrated intensity-independent polarization-sensitive switch operating at 1.3 mu m based on ordering in InGaAsP

Recently we have shown that the quaternary semiconductor InGaAsP spontaneously forms a mono-atomic superlattice oriented in [111](B)-direction if grown under suitable conditions by MOVPE. The superlattice-induced reduction of the crystal-symmetry leads to a much larger polarisation anisotropy as in ternary III/V-semiconductors, as the ordering affects both the group-III- and the group-V-sublattice. In this contribution we report on an optoelectronic switch, based on the absorption anisotropy for [110]- and [1 (1) over bar0]-polarised light. Switching between "on" and "off" depends on the polarisation angle only, but hardly on the intensity. (c) 2006 Elsevier B.V. All rights reserved

Agrichemical Placement Impacts on Alachlor and Nitrate Movement Through Boil in a Ridge Tillage System

Surface microrelief may influence the fate of agrichemicals in the soil by influencing surface water flow. The objective of this experiment was to determine the impact of agrichemical placement on agrichemical movement in a ridge tillage system. Alachlor, bromide, and calcium nitrate (15N labeled) were applied above fifteen grid lysimeters to either the ridge top or valley area of a ridge tillage system. The grid lysimeters allowed temporal and spatial fractionation of leachate. Sixteen hours after agrichemical application, 15 cm of water was applied with a rainfall simulator. During the simulated rainfall, water flowed from the ridge top to the valley and then into the soil profile. Surface water flow increased the amount of water collected in lysimeters placed under valley areas when compared with ridge areas, which in turn increased the movement of N fertilizer, bromide, and alachlor through the soil profile