Ilona: An advanced CAI Tutorial System for the Fundamentals of Logic

An advanced tutorial system for teaching the fundamentals of logic has been developed to run on UNIX work stations and commonly available micro-computers. An important part of this tutorial is the intelligent problem solving environment which allows students to practise wiriting logical sentences in mathematical notation. A natural language system for intelligent logic narrative analysis (ILONA) allows students to type in their own logical sentences in plain English and then have the computer check their working when they write these in mathematical form. ILONA is an intelligent tutoring system which allows students a great deal of initiative in problem solving and provides a degree of flexibility in answer evaluation not found in traditional CAI systems. The concepts and structures used in the development of ILONA are easily transferable to other domains

A Research-Based Curriculum for Teaching the Photoelectric Effect

Physics faculty consider the photoelectric effect important, but many erroneously believe it is easy for students to understand. We have developed curriculum on this topic including an interactive computer simulation, interactive lectures with peer instruction, and conceptual and mathematical homework problems. Our curriculum addresses established student difficulties and is designed to achieve two learning goals, for students to be able to (1) correctly predict the results of photoelectric effect experiments, and (2) describe how these results lead to the photon model of light. We designed two exam questions to test these learning goals. Our instruction leads to better student mastery of the first goal than either traditional instruction or previous reformed instruction, with approximately 85% of students correctly predicting the results of changes to the experimental conditions. On the question designed to test the second goal, most students are able to correctly state both the observations made in the photoelectric effect experiment and the inferences that can be made from these observations, but are less successful in drawing a clear logical connection between the observations and inferences. This is likely a symptom of a more general lack of the reasoning skills to logically draw inferences from observations.Comment: submitted to American Journal of Physic

Selective Earth-Abundant System for CO2 Reduction: Comparing Photo- and Electrocatalytic Processes

The valorization of CO2 via photo- or electrocatalytic reduction constitutes a promising approach toward the sustainable production of fuels or value-added chemicals using intermittent renewable energy sources. For this purpose, molecular catalysts are generally studied independently with respect to the photo- or the electrochemical application, although a unifying approach would be much more effective with respect to the mechanistic understanding and the catalyst optimization. In this context, we present a combined photo- and electrocatalytic study of three Mn diimine catalysts, which demonstrates the synergistic interplay between the two methods. The photochemical part of our study involves the development of a catalytic system containing a heteroleptic Cu photosensitizer and the sacrificial BIH reagent. The system shows exclusive selectivity for CO generation and renders turnover numbers which are among the highest reported thus far within the group of fully earth-abundant photocatalytic systems. The electrochemical part of our investigations complements the mechanistic understanding of the photochemical process and demonstrates that in the present case the sacrificial reagent, the photosensitizer, and the irradiation source can be replaced by the electrode and a weak Brønsted acid. © 2019 American Chemical Society

Heartwater : past, present and future : proceedings of a workshop held at Berg en Dal, Kruger National Park, on 8-16 September 1986

Antibodies in the sera of domestic ruminants that have been infected with Ehrlichia bovis and other ehrlichial agents cross-react with the Kümm strain of Cowdria ruminantium used in the indirect fluorescent antibody test as antigen. These cross-reactions are also shown by the Elisa test in which the Ball 3 strain of the heartwater agent is used as antigen.The articles have been scanned in colour with a HP Scanjet 5590; 600dpi. Adobe Acrobat XI Pro was used to OCR the text and also for the merging and conversion to the final presentation PDF-format.lmchunu2014mn201

Heartwater : past, present and future : proceedings of a workshop held at Berg en Dal, Kruger National Park, on 8-16 September 1986

Techniques for the rearing of Amblyomma species to be used in heartwater (Cowdria ruminantium) transmission experiments are discussed. These involve the breeding and maintenance of infected and noninfected strains of ticks. They include the feeding of ticks on sheep, rabbits, mice, tortoises and guinea fowl.The articles have been scanned in colour with a HP Scanjet 5590; 600dpi. Adobe Acrobat XI Pro was used to OCR the text and also for the merging and conversion to the final presentation PDF-format.lmchunu2014mn201

Mechanistic Insights into the Electrochemical Reduction of CO₂ Catalyzed by Iron Cyclopentadienone Complexes

In a previous paper we have demonstrated that the easily-synthesized class of iron(0) cyclopentadienone complexes constitutes a promising catalyst platform for the electrochemical conversion of CO2 to CO and H2O. One of the unusual features of these catalysts is that catalysis proceeds efficiently in aprotic electrolytes in the absence of acidic additives. Herein we present a detailed study of the underlying catalytic mechanisms. Using a combination of FTIR spectroelectrochemistry, DFT calculations, and nonelectrochemical control experiments, we have identified a number of catalytic intermediates including the active species and the product of catalyst deactivation. On the basis of these insights, we have carried out digital simulations in order to decipher the voltammetric profiles of the iron(0) cyclopentadienones. Further control experiments revealed that the anodic oxidation of the electrolyte constitutes the terminal proton source for the formation of CO and H2O. Taken together, our results suggest a competition between two coexisting catalytic pathways, one of which proceeds via a hitherto unknown Fe–Fe dimer as an active species