Using polyacrilamide with sprinkler irrigation to improve infiltration

ABSTRACT: Center-pivot irrigation systems often apply water at rates greater than the soil infiltration rate. Applying high molecular weight, water-soluble, anionic polyacrylamide (PAM) to the soil can improve infiltration and reduce soil erosion The objective of this study was to determine whether single and multiple PAM applications with sprinkler irrigation improved infiltration under field conditions. A two-year study conducted near Kimberly, Idaho, used a solid-set sprinkler system, and a one-year study conducted in Monte dos Alhos near Alvalade do Sado, Portugal, used a center pivot. At Kimberly, applying PAM with four irrigations (total applied PAM was 2.1 kg ha−1 in 2000 and 3.0 kg ha−1 in 2001) significantly reduced total measured runoff, from 5.9 mm (2000) and 9.2 mm (2001) for the control to 2.0 and 2.1 mm. Total measured soil erosion was also reduced from 52 and 34 kg ha−1 for the control to 21 and 5 kg ha−1 for the multiple PAM treatment. Applying similar or greater amounts of PAM with a single irrigation reduced erosion, but not runoff, compared with the control. In the Monte dos Alhos study, runoff was reduced by applying a total of 0.3 kg PAM ha−1 with a single irrigation (43 mm runoff) or three irrigations (65 mm runoff) compared with the control (111 mm runoff). Measured soil erosion was not significantly different among treatments. Applying PAM with multiple irrigations extended its effectiveness as long as the application rate was great enough to adequately stabilize the soil surface during the first irrigation

Using polyacrylamide with sprinkler irrigation to improve infiltration

Center-pivot irrigation systems often apply water at rates greater than the soil infiltration rate. Applying high molecular weight, water-soluble, anionic polyacrylamide (PAM) to the soil can improve infiltration and reduce soil erosion The objective of this study was to determine whether single and multiple PAM applications with sprinkler irrigation improved infiltration under field conditions. A two-year study conducted near Kimberly, Idaho, used a solid-set sprinkler system, and a one-year study conducted in Monte dos Alhos near Alvalade do Sado, Portugal, used a center pivot. At Kimberly, applying PAM with four irrigations (total applied PAM was 2.1 kg ha-1 in 2000 and 3.0 kg ha-1 in 2001) significantly reduced total measured runoff, from 5.9 mm (2000) and 9.2 mm (2001) for the control to 2.0 and 2.1 mm. Total measured soil erosion was also reduced from 52 and 34 kg ha 1 for the control to 21 and 5 kg ha 1 for the multiple PAM treatment. Applying similar or greater amounts of PAM with a single irrigation reduced erosion, but not runoff, compared with the control. In the Monte dos Alhos study, runoff was reduced by applying a total of 0.3 kg PAM ha 1 with a single irrigation (43 mm runoff) or three irrigations (65 mm runoff) compared with the control (111 mm runoff). Measured soil erosion was not significantly different among treatments. Applying PAM with multiple irrigations extended its effectiveness as long as the application rate was great enough to adequately stabilize the soil surface during the first irrigation

A novel enzymatically-mediated drug delivery carrier for bone tissue engineering applications: combining biodegradable starch-based microparticles and differentiation agents

In many biomedical applications, the performance of biomaterials depends largely on their degradation behavior. For instance, in drug delivery applications, the polymeric carrier should degrade under physiological conditions slowly releasing the encapsulated drug. The aim of this work was, therefore, to develop an enzymaticmediated degradation carrier system for the delivery of differentiation agents to be used in bone tissue engineering applications. For that, a polymeric blend of starch with polycaprolactone (SPCL) was used to produce a microparticle carrier for the controlled release of dexamethasone (DEX). In order to investigate the effect of enzymes on the degradation behavior of the developed system and release profile of the encapsulated osteogenic agent (DEX), the microparticles were incubated in phosphate buffer solution in the presence of a-amylase and/or lipase enzymes (at physiological concentrations), at 37 C for different periods of time. The degradation was followed by gravimetric measurements, scanning electron microscopy (SEM) and Fourier transformed infrared (FTIR) spectroscopy and the release of DEX was monitored by high performance liquid chromatography (HPLC). The developed microparticles were shown to be susceptible to enzymatic degradation, as observed by an increase in weight loss and porosity with degradation time when compared with control samples (incubation in buffer only). For longer degradation times, the diameter of the microparticles decreased significantly and a highly porous matrix was obtained. The in vitro release studies showed a sustained release pattern with 48% of the encapsulated drug being released for a period of 30 days. As the degradation proceeds, it is expected that the remaining encapsulated drug will be completely released as a consequence of an increasingly permeable matrix and faster diffusion of the drug. Cytocompatibility results indicated the possibility of the developed microparticles to be used as biomaterial due to their reduced cytotoxic effects

Controlled release strategies for bone, cartilage, and osteochondral engineering: part I: recapitulation of native tissue healing and variables for the design of delivery systems

The potential of growth factors to stimulate tissue healing through the enhancement of cell proliferation, migration, and differentiation is undeniable. However, critical parameters on the design of adequate carriers, such as uncontrolled spatiotemporal presence of bioactive factors, inadequate release profiles, and supraphysiological dosages of growth factors, have impaired the translation of these systems onto clinical practice. This review describes the healing cascades for bone, cartilage, and osteochondral interface, highlighting the role of specific growth factors for triggering the reactions leading to tissue regeneration. Critical criteria on the design of carriersfor controlled release of bioactive factors are also reported, focusing on the need to provide a spatiotemporal control over the delivery and presentation of these molecules.The authors thank Fundacao para a Ciencia e Tecnologia for V.E.Santo's PhD grant (SFRH/BD/39486/2007). This work was carried out under the scope of the European FP7 Project Find and Bind (NMP4-SL-2009-229292) and Project MIT/ECE/0047/2009

Update on the correlation of the highest energy cosmic rays with nearby extragalactic matter

Data collected by the Pierre Auger Observatory through 31 August 2007 showed evidence for anisotropy in the arrival directions of cosmic rays above the Greisen-Zatsepin-Kuz'min energy threshold, \nobreak{$6\times 10^{19}$eV}. The anisotropy was measured by the fraction of arrival directions that are less than $3.1^\circ$ from the position of an active galactic nucleus within 75 Mpc (using the V\'eron-Cetty and V\'eron $12^{\rm th}$ catalog). An updated measurement of this fraction is reported here using the arrival directions of cosmic rays recorded above the same energy threshold through 31 December 2009. The number of arrival directions has increased from 27 to 69, allowing a more precise measurement. The correlating fraction is $(38^{+7}_{-6})$, compared with $21$ expected for isotropic cosmic rays. This is down from the early estimate of $(69^{+11}_{-13})$. The enlarged set of arrival directions is examined also in relation to other populations of nearby extragalactic objects: galaxies in the 2 Microns All Sky Survey and active galactic nuclei detected in hard X-rays by the Swift Burst Alert Telescope. A celestial region around the position of the radiogalaxy Cen A has the largest excess of arrival directions relative to isotropic expectations. The 2-point autocorrelation function is shown for the enlarged set of arrival directions and compared to the isotropic expectation.Comment: Accepted for publication in Astroparticle Physics on 31 August 201

The Fluorescence Detector of the Pierre Auger Observatory

The Pierre Auger Observatory is a hybrid detector for ultra-high energy cosmic rays. It combines a surface array to measure secondary particles at ground level together with a fluorescence detector to measure the development of air showers in the atmosphere above the array. The fluorescence detector comprises 24 large telescopes specialized for measuring the nitrogen fluorescence caused by charged particles of cosmic ray air showers. In this paper we describe the components of the fluorescence detector including its optical system, the design of the camera, the electronics, and the systems for relative and absolute calibration. We also discuss the operation and the monitoring of the detector. Finally, we evaluate the detector performance and precision of shower reconstructions.Comment: 53 pages. Submitted to Nuclear Instruments and Methods in Physics Research Section

Advanced functionality for radio analysis in the Offline software framework of the Pierre Auger Observatory

The advent of the Auger Engineering Radio Array (AERA) necessitates the development of a powerful framework for the analysis of radio measurements of cosmic ray air showers. As AERA performs "radio-hybrid" measurements of air shower radio emission in coincidence with the surface particle detectors and fluorescence telescopes of the Pierre Auger Observatory, the radio analysis functionality had to be incorporated in the existing hybrid analysis solutions for fluoresence and surface detector data. This goal has been achieved in a natural way by extending the existing Auger Offline software framework with radio functionality. In this article, we lay out the design, highlights and features of the radio extension implemented in the Auger Offline framework. Its functionality has achieved a high degree of sophistication and offers advanced features such as vectorial reconstruction of the electric field, advanced signal processing algorithms, a transparent and efficient handling of FFTs, a very detailed simulation of detector effects, and the read-in of multiple data formats including data from various radio simulation codes. The source code of this radio functionality can be made available to interested parties on request.Comment: accepted for publication in NIM A, 13 pages, minor corrections to author list and references in v