1,093 research outputs found
Decomposition products of s-Triazine herbicides by electron-transfer in acidic aqueous media.
No full textThe reduction of atrazine and terbutylazine was preceded by protonation equilibrium. Three protonation sites of the s-triazine molecule determined the structure of the final reduction product. Protonation was investigated by the change of UV-Vis spectra. Two slightly different pKs corresponding to protonation on N5 and N1 heteroatoms were evaluated. The principal reduction pathway involved the cleavage of a chlorine atom. A small quantity of desethylatrazine was detected in the most acidic media
ELECTROCHEMISTRY OF S-TRIAZINE HERBICIDES - REDUCTION OF ATRAZINE AND TERBUTYLAZINE IN AQUEOUS-SOLUTIONS
No full textThe electrochemical behavior of both herbicides is qualitatively similar. The two-electron reduction of atrazine (2-chloro-4-ethylamino 6-isopropylamino-1,3,5-triazine) proceeds only in acidic media where the preceding protonation takes place (pK = 1.44). In solutions of higher pH (2-4) the observed reduction current is kinetically controlled by protonation and the estimated value of the protonation rate constant is k(r) = 2400 +/- 400 mol(-1) 1 s(-1). The products of reduction were identified by large-scale electrolysis followed by GC-MS analysis. The electron transfer reaction causes cleavage of the Cl atom and loss of the ethyl group yielding the respective products in the ratio approximately 4:1. The electrochemical properties of terbutylazine are characterized by the protonation constant pK = 2.37 and rate constant k(r) = 1900 +/- 200 mol(-1) 1 s(-1)
Meeting needs: A staff development resource for redesigning sociology courses according to an Outcomes-based model
No full textThis paper describes the development of “Changing Outcomes - Exploring Needs Based Course Design in Universities” a Web/CD hybrid application incorporating an expert system for analysis and redesigning of courses. This interactive staff development tool will assist academics in reconceptualising courses according to an outcomes-based model. The development of this application through educational design, interface design and expert system design is described, together with the results of formative evaluation of the product and an analysis of project management data gathered throughout the project
Energy studies and the art of going online
No full textOffering interactive, multimedia courses via the Internet or CDROM is seen as one of the most promising ways of achieving the goals of cost effective, flexible, global education in a more competitive local and international student market. One of the major questions that still has to be answered, however, is whether interactive, online instructional methods can only be used to supplement traditional teaching practises, or whether they can effectively replace or even improve on them. This paper describes our experience in the design and development, so far, of the core units of a Postgraduate Diploma in Energy Studies to be offered by Murdoch University in the on-line delivery mode. This includes a discussion of some of the pedagogical and teaching/learning issues that needed to be addressed in developing such things as a common Web Browser interface and the way material is presented in an online, interactive mode. Some ideas of "What Works and Why", are given based on an evaluation of student attitudes to one of these units that has already been offered in dual mode
Energy sensitive Timepix silicon detector for electron imaging
No full textWe present the first measurements with the energy sensitive Timepix pixel detector for electron imaging. The hybrid pixel detector consists of a silicon detector, 300 μm thick, bump-bonded to the Timepix readout chip developed by the Medipix2 collaboration (256×256 pixels, 55 μm pitch, 14.08×14.08 mm2 sensitive area). Each Timepix pixel can be independently operated in one of three modes: 1. counting of the detected particles; 2. measurement of the particle energy; 3. measurement of the time of particle interaction. The energy measurement in the second mode is performed via the determination of the ???Time-Over-Threshold??? (TOT). The ionization charge generated by the particle along its track is often registered by several adjacent pixels forming a cluster. The shape of the cluster is affected also by lateral charge spread. It is often possible to determine a particle type, its energy, entrance point and direction by on-line or off-line analysis of shapes of recorded clusters. This way an influence of background or noise can be significantly reduced in measured data.
The energy spectrum for 90Sr/90Y electrons was measured by Timepix detector and compared with the ??- decay spectrum and the Monte Carlo simulated spectrum. In order to improve spatial resolution, we analyze the tracks of all electrons and substitute each cluster with the position of its centroid. We measured the spatial resolution with a 90Sr/90Y source irradiating, at 10 cm distance, a 100 μm thick steel edge slightly tilted with respect to the detector lines. The oversampled Line Spread Function shows a FWHM of 27.5±1.1 ??m. The Timepix Si detector will be used for digital autoradiography with ??- and ??+ tracers, and it could be used for electron microscopy. First tests were performed with a 14C autoradiography sample
The use of a QTVR image database for teaching veterinary radiology and diagnostic ultrasound to distance education students
No full textThe result of the project described in this paper is an innovative use of Quicktime Virtual Reality (QTVR) for display and manipulation of veterinary radiographs and ultrasound images, within a database developed for use in the Veterinary Diagnostic Imaging unit of the Master of Veterinary Studies at Murdoch University. One of the aims of this project was to find an alternative for the bulky sets of radiographs used by external students for their case based coursework and assessment activities. The QTVR solution provides a means by which students can move and zoom within images, resize images and compare images side by side. QTVR also allows important areas of images to be highlighted by hotspots, allowing annotation of images, which is helpful for assisting external students. Some of the priorities of this project were to maintain the detail and the depth of the hard copy radiographs in the QTVR images, to simulate the problem solving process used in reading radiographs, and to improve the learning outcomes by highlighting and annotating important areas of images. It was hoped that this solution would provide a more cost effective and convenient method of delivery of large numbers of images to external students. In the subsequent cost benefit analysis, it was found that the innovation described here offers many economic advantages to the School of Veterinary Clinical Science
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