Failure mechanisms of thermal barrier coatings exposed to elevated temperatures

The failure of a ZrO2-8%Y2O3/Ni-14% Al-0.1% Zr coating system on Rene 41 in Mach 0.3 burner rig tests was characterized. High flame and metal temperatures were employed in order to accelerate coating failure. Failure by delamination was shown to precede surface cracking or spalling. This type of failure could be duplicated by cooling down the specimen after a single long duration isothermal high temperature cycle in a burner rig or a furnace, but only if the atmosphere was oxidizing. Stresses due to thermal expansion mismatch on cooling coupled with the effects of plastic deformation of the bond coat and oxidation of the irregular bond coat are the probable life limiting factors. Heat up stresses alone could not fail the coating in the burner rig tests. Spalling eventually occurs on heat up but only after the coating has already failed through delamination

IMMUNOCONTRACEPTION AND POSSIBLE APPLICATION IN WILDLIFE DAMAGE MANAGEMENT

lmmunocontraception technology appears to have viable application in wildlife damage management. However, administration of these vaccines is presently performed by syringe injection or remote delivery by darts or bio-bullets. In order for immunocontraception to be successful for broad scale application to free-roaming animals, the vaccine must be delivered in an oral form. Recent advances in molecular biology, immunology, and pathology of mucosal infection gives us tools to develop effective oral vaccines. Oral immunocontraceptive vaccine encapsulated in adhesive liposomes or non-virulent live vectors holds promise as a practical approach for immunocontraception of free-roaming wildlife. Issues of safety, species specificity, regulatory constraints, and field application of the vaccine will need to be addressed

Delivery of lmmunocontraceptive Vaccines for Wildlife Management

Immunocontraceptive technology appears to be a viable approach for population control of nuisance species of wildlife. The administration of immunocontraceptive vaccines is presently performed by syringe injection or by remote delivery via darts or biobullets. In order for immunocontraception to be successful in free-roaming animals, the vaccine must be delivered in an oral form. Recent advances in molecular biology, immunology, and pathology of mucosal infections give us tools to develop effective oral vaccines. Oral vaccines encapsulated in either biodegradable microspheres, synthetic adhesive liposomes, or nonvirulent live vectors hold promise as a practical approach for immunocontraception of free-roaming wildlife. Issues of safety, species specificity, and field application of the vaccine will need to be addressed

IMMUNOCONTRACEPTION AND POSSIBLE APPLICATION IN WILDLIFE DAMAGE MANAGEMENT

lmmunocontraception technology appears to have viable application in wildlife damage management. However, administration of these vaccines is presently performed by syringe injection or remote delivery by darts or bio-bullets. In order for immunocontraception to be successful for broad scale application to free-roaming animals, the vaccine must be delivered in an oral form. Recent advances in molecular biology, immunology, and pathology of mucosal infection gives us tools to develop effective oral vaccines. Oral immunocontraceptive vaccine encapsulated in adhesive liposomes or non-virulent live vectors holds promise as a practical approach for immunocontraception of free-roaming wildlife. Issues of safety, species specificity, regulatory constraints, and field application of the vaccine will need to be addressed

WILDLIFE CONTRACEPTION: TARGETING THE OOCYTE

The USDA’s National Wildlife Research Center (NWRC) has successfully researched and developed a number of chemical and immunologically-based wildlife contraceptives. Diazacon™ interferes with cholesterol metabolism and disrupts steroidogenesis, while nicarbazin (registered as OvoControl-P® and OvoControl-G®) disrupts the structure of the vitelline membrane of bird eggs. Immunologically-based agents act to stimulate targeted antibody production. GonaCon™ causes the host’s immune system to bind gonadotropin releasing hormone, preventing ovulation, while SpayVac™ prevents fertilization of the postovulatory oocyte. This kind of target specificity can be highly advantageous. A number of oocyte-only control contraceptive strategies are currently being researched at the NWRC. 4-Vinylcyclohexene diepoxide (VCD) is an industrial chemical which is specifically ovotoxic, depleting the ovarian oocyte pool with repeated exposure. Research into VCD efficacy as well as the comparability of a similar diepoxide, ERL 4221, in rats and pigs is in progress. Immunological inhibition of recently discovered oocyte-secreted proteins which regulate follicular development in mammals is also of interest. Two such proteins, growth differentiation factor 9 (GDF9) and bone morphogenic protein 15 (BMP15), are highly specific targets for the suppression or elimination of folliculogenesis. These oocyte-specific strategies may offer new, effective alternatives for wildlife contraception

Seven Years of White-Tailed Deer Immunocontraceptive Research at Penn State University: A Comparison of Two Vaccines

PZP and GnRH immunocontraceptive vaccines were each tested in white-tailed deer (Odocoileus virginianus) . Vaccination with PZP produced reversible infertility lasting 1 to 4 years. The first two years of active immunization resulted in an 89% reduction in fawning. Reduction in fawning for the 7-year study containing 4 years of no boosting was 72%. PZP immunization resulted in multi-estrus behavior, with contracepted deer returning to estrus up to 7 times. A five year study of GnRH immunization was conducted in both male and female deer. Treatment of does led to reduced fawning rates, reduced estrus behavior and reduced concentrations of progesterone. During active immunization GnRH does bred to untreated bucks had an 88% reduction in fawning caused by either immunocontraception or immunocontragestion. Reduction in fawning for the 5 year study containing 2 years of no boosting was 74%. The vaccine effect was reversible and directly related to the antibody titer. Infertility lasted up to two years without boosting. GnRH immunized bucks had no interest in sexual activity when paired with control females. Depending on the immunization schedule, antlers either dropped early or remained in velvet

Identification of Knock in NACA High-Speed Photographs of Combustion in a Spark-Ignition Engine

Report presents the results of a study of combustion in a spark-ignition engine given in NACA Technical Reports 704 and 727. The present investigation was made with the NACA high-speed motion-picture camera, operating at 40,000 photographs a second, and with a cathode-ray oscillograph operating on a piezoelectric pick-up in the combustion chamber. Photographs are presented showing that the origin of knock is not necessarily in the end gas. The data obtained indicates that knock takes place only in a part of the cylinder charge which has been previously ignited either by autoignition or by the passage of the flame fronts but which has not burned to completion. Mottled regions in the high-speed Schlieren photographs are demonstrated to represent combustion regions

The Interdependence of Various Types of Autoignition and Knock

A study of the relations existing among pin-point autoignition, homogeneous autoignition, and knock has been made by means of the NACA high-speed camera and the full-view combustion apparatus. High-speed photographic records of combustion, together with corresponding pressure-time traces, of benzene, 2,2,3-trimethylbutane, S-4, and M-4 fuels at various engine conditions have shown the engine conditions under which each of these phenomena occur and the relation of these phenomena to one another

A Study of Industrial Arts Graduates of North Texas State University from 1956 through 1965

"This study was conducted to collect and analyze data relative to the employment status of industrial arts graduates."--1

The Present Status of Systematic Mammalogy in Iowa with Some Notes on Recent Mammal Collecting Within the State

In this short discussion the author will try to explore the present status of systematic mammalogy in this state and will show by his own trapping results that there is a great deal of work yet to be done. Thomas G. Scott (1937) published a paper entitled Mammals of Iowa in the Iowa State College Journal of Science. In the introduction he implies that the purpose of the paper is to stimulate interest in the systematics of mammals in Iowa. In searching through the recent literature on the subject the author has come to the conclusion that it did not stimulate interest and there has consequently been a dearth of information published since. There have been only 4 or possibly 5 additions to the faunal list since 1937. There have been a few name changes and some sub-specific splitting of inclusive species, mostly by workers in other states. This splitting has resulted, in some cases in the fact that Iowa has within its borders the intergradation zone for two subspecies named in the states east and west or north and south. There is at the present time at least 16 species of mammals which have two or more subspecies coming together in Iowa. Most of these divide the state east and west i.e., Cinereous, Shrew, Mole, Mink, Muskrat, Pocket Gopher, and Striped Skunk, but a few divide the state north and south, i.e., Red Squirrel, Gray Squirrel, Long Tail Weasel, and Lemming Mouse. The approximate geographic distributions of these animals can only be determined by actual specimen gathering from the area covered by their distribution