Gel drying is a critical step in the sol-gel synthesis of Al2O3 and Al2O3-SiC composites. Problems exist during the drying stage that affect the monolithic properties of the sintered products. Classical drying theory was applied to the drying behavior of Al2O3 and Al2O3-SiC composites in an effort to optimize the drying process and understand the controlling mechanisms.

Methods of glass repair were explored. Sol-gel coating and heat treatment by either conventional resistance heating or microwave hybrid heating (MHH) were combined to provide a promising repair method. Repair resulted from filling intentionally induced cracks with sol-gel material via dip coating and then developing strong bonding between the densified gel and the crack sides. Heating the coated samples to the annealing point of the glass resulted in higher fracture strength. Glasses with large crack sizes appeared to need more than one coating while a single coating layer was sufficient with small cracks. Over the range of temperatures studied, microwave hybrid heating produced the same results as conventional heating for all material parameters under consideration. Microwave heating of the glass without the assistance of a microwave susceptor (stand-alone microwave heating or two-step heating using conventional then microwave heating) resulted in large data scattering.

Chapter 16 Effect of Heat Treatment on the Oxidation of Hot-Pressed Si3N4 as Determined by Infrared Reflection Analysis J. M. Barrett, J. M. Barrett Materials Science and Engineering Dept. University of Florida, Gainesville, Fla. 32611Search for more papers by this authorL. L. Hench, L. L. Hench Materials Science and Engineering Dept. University of Florida, Gainesville, Fla. 32611Search for more papers by this authorS. Bernstein, S. Bernstein Materials Science and Engineering Dept. University of Florida, Gainesville, Fla. 32611Search for more papers by this authorD. E. Clark, D. E. Clark Materials Science and Engineering Dept. University of Florida, Gainesville, Fla. 32611Search for more papers by this authorS. W. Freiman, S. W. Freiman Fracture & Deformation Div. National Bureau of Standards Washington, D.C. 20234Search for more papers by this author J. M. Barrett, J. M. Barrett Materials Science and Engineering Dept. University of Florida, Gainesville, Fla. 32611Search for more papers by this authorL. L. Hench, L. L. Hench Materials Science and Engineering Dept. University of Florida, Gainesville, Fla. 32611Search for more papers by this authorS. Bernstein, S. Bernstein Materials Science and Engineering Dept. University of Florida, Gainesville, Fla. 32611Search for more papers by this authorD. E. Clark, D. E. Clark Materials Science and Engineering Dept. University of Florida, Gainesville, Fla. 32611Search for more papers by this authorS. W. Freiman, S. W. Freiman Fracture & Deformation Div. National Bureau of Standards Washington, D.C. 20234Search for more papers by this author Book Editor(s):William J. Smothers, William J. SmothersSearch for more papers by this author First published: 01 January 1980 https://doi.org/10.1002/9780470291030.ch16Citations: 1Book Series:Ceramic Engineering and Science Proceedings AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinked InRedditWechat Citing Literature Proceedings of the 2nd and 3rd Annual Conference on Composites and Advanced Materials: Ceramic Engineering and Science Proceedings, Volume 1 RelatedInformation

Preparation and characterization of ceramic materials in the Ti-Si-C system are presented. Mixtures of titanium, silicon and carbon powders were ignited by microwave energy. Powders prepared by conventional SHS and microwave-initiated SHS were compared. Compositional characteristics of these powders were determined using X-ray diffraction. Conventionally-ignited SHS compacts, with no sustainable heating after ignition, resulted in a product with a large fraction of TiC. Conventionally-ignited SHS samples that were sustainably heated for up to 30 minutes at 1400° −1450° C resulted in a product composed of TiC with traces of Ti3SiC2. Samples ignited and sustainably heated with microwave energy for up to 30 minutes at 1400°-1450° C resulted in a product that maintained a high fraction of the Ti3SiC2 phase. Microwave energy seemed to inhibit the decomposition and actually favor the formation of the Ti3SiC2 phase starting from Ti-Si-C powder mixtures.

Nanocomposites Al2O3/SiC powders have been synthesized by a microwave-induced combustion process using aluminium nitrate, beta -SiC (powders) and urea, The effect of preheating the solution before the combustion reaction and the effect of the characteristic of the SiC powders, in the crystallization of the alumina, by combustion reaction were evaluated. The preheating of the liquid solution at about 150 degreesC before heating in the microwave oven guaranteed the homogeneity of the solution and modified the characteristics of the products. The mechanism of heating in the microwave oven was favorable to the uniform emission of gases and fast dissipation of heat, promoting formation of different foam and nanocomposites Al2O3/SiC powders with characteristics that were different from those produced conventionally. The direct conversion of liquid solution to the final solid product was assured, and the segregation commonly found in conventional mixing of powders (alumina-SiC) was avoided. The different characteristics of the SiC powders have strong influence in the flame time of the combustion reaction and consequently in the crystallization of the alumina and characteristics of the Al2O3/SiC nanocomposites powders. The SiC particles were not oxidized during the reaction and partial reaction with alumina did not occur; SiC particles remained as a distinct and separate phase.

Microwave processing was utilized to decompose oxides to their constituent metal. Samples were processed in a microwave transparent, porous silica refractory in a self-sustaining non-oxidizing atmosphere. Processing parameters were carefully controlled and resulted in metal discs. The Richardson-Ellingham chart of the oxidation of metals was used to determine the temperatures and atmosphere required to induce decomposition. This technique offers a unique method to produce a wide range of ceramic-metal composites.

A Logistic-Normal random variable (Y) is obtained from a Normal random variable (X) by the relation Y = (ex)/(1 + ex). In Monte-Carlo analysis of decision trees, Logistic-Normal random variates may be used to model the branching probabilities. In some cases, the probabilities to be modeled may not be independent, and a method for generating correlated Logistic-Normal random variates would be useful. A technique for generating correlated Normal random variates has been previously described. Using Taylor Series approximations and the algebraic definitions of variance and covariance, we describe methods for estimating the means, variances, and covariances of Normal random variates which, after translation using the above formula, will result in Logistic-Normal random variates having approximately the desired means, variances, and covariances. Multiple simulations of the method using the Mathematica computer algebra system show satisfactory agreement with the theoretical results.

Suspect feed was collected from two broiler houses in which random necropsies revealed proventricular enlargement (proventriculitis). Feed also was collected from two unaffected houses on the same farm. Broiler chicks received the suspect feed, feed from unaffected houses, and a control feed for 2 wk. Thereafter, all groups were fed control feed until 4 wk of age. The suspect feed caused a 70 to 100% incidence of obvious proventricular enlargement, which was significantly higher than the basal 10 to 30% incidence observed in broilers fed control feed or feed from unaffected houses. The incidence of proventricular enlargement reverted to control levels when birds previously fed suspect feed were switched to control feed during the last 2 wk of the experiment. The suspect feed contained Cu, added as copper sulfate, in excess of 200 ppm. In a second experiment, feeds formulated to contain 0, 250, 500, and 750 ppm Cu were fed to broilers for 4 wk. Dietary Cu at and above 250 ppm significantly increased the incidence of proventriculitis. Dietary Cu in excess of 200ppm can trigger the classic symptoms of proventricular enlargement and proventriculitis in broilers.

The c-kit protein is a transmembrane tyrosine kinase receptor that binds the growth factor stem cell factor. Mutant alleles of the genes coding for both the receptor (c-kit) and its ligand (stem cell factor) affect gametogenesis, development of melanoblasts and some aspects of haematopoiesis. The aim of this study was to examine expression of the c-kit gene during folliculogenesis in fetal sheep ovaries using in situ hybridization. A 422 bp cDNA encoding the extracellular domain of the c-kit protein was amplified from sheep ovarian RNA using reverse-transcription-polymerase chain reaction (RT-PCR), cloned and sequenced. Riboprobes transcribed from the ovine cDNA encoding c-kit were used to detect the presence of mRNA encoding c-kit within the ovaries of fetal sheep on days 90, 100, 120 and 135 of gestation (term = 147 days). In day 90 and 100 fetal ovaries, mRNA encoding c-kit was not detected in association with oogonia during the period of meiosis (to prophase I) but was present in some of the isolated oocytes. In ovaries from day 90 to day 135, mRNA encoding c-kit was detected in the oocytes at every stage of follicular growth - primordial through to antral follicles. This pattern of localization is consistent with that demonstrated in mice.

Journal Article The effects of intention on recall following brain injury Get access D.E. Clark, D.E. Clark Search for other works by this author on: Oxford Academic PubMed Google Scholar M.L. Yaguda M.L. Yaguda Search for other works by this author on: Oxford Academic PubMed Google Scholar Archives of Clinical Neuropsychology, Volume 10, Issue 4, 1995, Page 307, https://doi.org/10.1093/arclin/10.4.307 Published: 01 July 1995

Journal Article The effects of shallow versus deep processing on recall in head-injured subjects Get access D.E. Clark, D.E. Clark New Medico Rehabilitation and Skilled Nursing Center of Cortland Search for other works by this author on: Oxford Academic PubMed Google Scholar M.L. Yaguda M.L. Yaguda New Medico Rehabilitation and Skilled Nursing Center of Cortland Search for other works by this author on: Oxford Academic PubMed Google Scholar Archives of Clinical Neuropsychology, Volume 7, Issue 4, 1992, Pages 322–323, https://doi.org/10.1093/arclin/7.4.322a Published: 01 July 1992

Journal Article Effects of dilantin toxicity on measures of cognitive function: A case study Get access D. E. Clark D. E. Clark New Medico Rehabilitation and Skilled Nursing Center of Cortland Search for other works by this author on: Oxford Academic PubMed Google Scholar Archives of Clinical Neuropsychology, Volume 5, Issue 2, 1990, Page 161, https://doi.org/10.1093/arclin/5.2.161a Published: 01 April 1990

Sol-gel processing may provide an alternative to the current tape cast powder method for manufacturing alumina substrates. The two methods are compared and advantages/disadvantages are discussed. One potential disadvantage of the sol-gel derived alumina substrates has been their brittleness after drying. The use of glycerol improves the flexibility of the prefired dried gels, making it possible to fabricate a variety of shapes through punching, cutting and laminating.

Significant advances have been made during the last 15 years in our understanding of glass surfaces and their environmental reactivity. The major reason for this advancement is the large array of surface analytical techniques that has been developed and applied to many industrial problems. One specific area of research where surface analysis has been proven valuable is glass corrosion. Until recently, the principal methods for studying degradation of glasses were weight loss measurements and solution analytical techniques. Neither of these provide information on surface alterations resulting from corrosion. Consequently, very little was known about the variety of mechanisms by which glass corrosion occurs. Currently, a multi-technique approach is being used in many laboratories around the world in order to achieve a better understanding of corrosion on glasses designed for immobilizing nuclear wastes. Similar approaches are being taken to solve problems related to conventional glass fabrication, glass preservation, and to new glass manufacturing processes based on sol-gel technology. In the present paper several techniques which are being routinely used to characterize glass surfaces are discussed. These include Fourier transform infrared reflection spectroscopy (FT-IRRS), secondary ion mass spectroscopy (SIMS), Auger electron spectroscopy coupled with ion milling (AES-IM) and scanning electron microscopy coupled with energy dispersive spectroscopy (SEM-EDS). Each of these techniques provide unique information about glass surfaces, and when used in combination can yield solutions to complex industrial and scientific problems.