An Analysis and Evaluation of Chemical Education Selected South Dakota Secondary Schools

In the past fifty years, numerous achievements have been made in the science of chemistry. Such achievements have required changes, both in industrial chemistry and in the teaching of chemistry. Traditionally, beginning chemistry has been taught as a descriptive science. Even presently, many secondary schools, colleges, and universities, offer a factual course emphasizing the factual data rather than the basic principles. Although teaching chemistry descriptively has appeared adequate in the past, because of the extensive volume of knowledge available today, such a method of instruction seem questionable. More than ever before there seems to be a need for a logical and effective means of teaching secondary school chemistry. There also seems to be a need for a course which will present the modern nature and the methods of preset day science. Within the last decade, two introductory high school chemistry courses have been introduced. They are the Chemical Education Material Study and the Chemical Bond Approach Project. It is one of their objectives of this study to examine the role of the chemistry laboratory, with special reference to the Chemical Bond Approach Project and the Chemical Education Material Study

A sintering model for SiC(sub)w/Si3N4 composites

Presented is a model which suggests that it should be possible to pressureless sinter a SiC(sub w)/ Si3N4 composite to theoretical density. Prior failure to achieve complete densification by sintering is attributed to the use of compositions which result in a glass deficit. There is one basic premise for this model. The ratio of glass amount to surface area of nonglass constituents must be the same for both composite and sinterable monolithic Si3N4. This model suggests that whisker and grain sizes and whisker loading influence the glass amount necessary for successful sintering of composites. According to the model, a large glass amount will be necessary for successful sintering of these composites. However, grain boundary thicknesses in the composite will be less than those in the analogous monolithic materials. This suggests that good high temperature strength may still be attained. A recent report supports the predictions of the model

Slurry-pressing consolidation of silicon nitride

A baseline slurry-pressing method for a silicon nitride material is developed. The Si3N4 composition contained 5.8 wt percent SiO2 and 6.4 wt percent Y2O3. Slurry-pressing variables included volume percent solids, application of ultrasonic energy, and pH. Twenty vol percent slurry-pressed material was approximately 11 percent stronger than both 30 vol percent slurry-pressed and dry-pressed materials. The Student's t-test showed the difference to be significant at the 99 percent confidence level. Twenty volume percent (300 h) slurry-pressed test bars exhibited strengths as high as 980 MPa. Large, columnar beta-Si3N4 grains caused failure in the highest strength specimens. The improved strength correlated with better structural uniformity as determined by radiography, optical microscopy, and image analysis

Ceramics for engines

The NASA Lewis Research Center's Ceramic Technology Program is focused on aerospace propulsion and power needs. Thus, emphasis is on high-temperature ceramics and their structural and environmental durability and reliability. The program is interdisciplinary in nature with major emphasis on materials and processing, but with significant efforts in design methodology and life prediction

Ceramics for engines

Structural ceramics were under nearly continuous development for various heat engine applications since the early 1970s. These efforts were sustained by the properties that ceramics offer in the areas of high-temperature strength, environmental resistance, and low density and the large benefits in system efficiency and performance that can result. The promise of ceramics was not realized because their brittle nature results in high sensitivity to microscopic flaws and catastrophic fracture behavior. This translated into low reliability for ceramic components and thus limited their application in engines. For structural ceramics to successfully make inroads into the terrestrial heat engine market requires further advances in low cost, net shape fabrication of high reliability components, and improvements in properties such as toughness, and strength. These advances will lead to very limited use of ceramics in noncritical applications in aerospace engines. For critical aerospace applications, an additional requirement is that the components display markedly improved toughness and noncatastrophic or graceful fracture. Thus the major emphasis is on fiber-reinforced ceramics

A determination of the variation of soil moisture in three plots of soil during one month's growing period

Citation: Kiser, Orville M. and Praeger, Herman A. A determination of the variation of soil moisture in three plots of soil during one month's growing period. Senior thesis, Kansas State Agricultural College, 1908.Introduction: In choosing this work for our thesis we have intended to show the variation of soil moisture to a depth of four feet in three different plots; wheat, corn, and alfalfa, respectively, during the spring season from April 22 to May 21, ’08. The wheat and alfalfa made a good growth during this time while the corn was planted toward the end of the month and was coming up at the close of the experiment

Lean on ME(dia): Helping Pre-Service Teachers to Recognize the Value of Media Integration Partnerships in the K-6 Classroom

Seasoned educators know that media specialists regularly support classroom teachers, though far too few new teachers are aware of this partnership opportunity. This presentation will consist of an interactive session in which the performance responsibilities and overlap of the classroom teacher and library media specialist are discussed, with specific attention paid to implementation in the pre-service environment. Presenters will showcase various examples of pre-service teacher work and insights, using media to complement and supplement existing curriculum, which foster an emphasis on student voice and student choice through the use of various media technologies. Session participants will engage in hands-on activities, dialogue surrounding the use of media integration partnerships for K-6 classroom educators, and modeling best practices of media usage in a variety of formats to meet the needs of diverse learners in the teacher preparation program setting