Hydrogen adsorption and diffusion, and subcritical-crack growth in high-strength steels and nickel base alloys

Coordinated studies of the kinetics of crack growth and of hydrogen adsorption and diffusion were initiated to develop information that is needed for a clearer determination of the rate controlling process and possible mechanism for hydrogen enhanced crack growth, and for estimating behavior over a range of temperatures and pressures. Inconel 718 alloy and 18Ni(200) maraging steel were selected for these studies. 18Ni(250) maraging steel, 316 stainless steel, and iron single crystal of (111) orientation were also included in the chemistry studies. Crack growth data on 18Ni(250) maraging steel from another program are included for comparison. No sustained-load crack growth was observed for the Inconel 718 alloy in gaseous hydrogen. Gaseous hydrogen assisted crack growth in the 18Ni maraging steels were characterized by K-independent (Stage 2) extension over a wide range of hydrogen pressures (86 to 2000 torr or 12 kN/m2 to 266 kN/m2) and test temperatures (-60 C to +100 C). The higher strength 18Ni(250) maraging steel was more susceptible than the lower strength 200 grade. A transition temperature was observed, above which crack growth rates became diminishingly small

Verde que te quiero verde: una mirada feminista para la conservación de la biodiversidad

In this article we provide a brief introduction of ecofeminism in order to highlight its encounters and differences with proposals of conservation biology. We propose that ecofeminism has numerous epistemological and ethical-political contributions that can enrich the practices of conservation biology and generate a critical view on the role of science in environmental issues. We will examine two elements of analysis, particularly relevant to ecofeminism. The first refers to the modern notion of nature and the dualist perspective that separates nature from culture. The second refers to the traditional epistemology of natural sciences, linked to the idea of objectivity and neutrality, as well as the role assigned to the latter in environmental problems. Subsequently, we will contrast these criticisms with the discourses of conservation biology. We will try to examine to what extent the assumption, criticized by ecofeminismo, are reproduced as well as to what extent common inquiries appear Our analysis indicates that to a certain extent some elements of ecofeminism seem to be achieving some impact on conservation biology, though not broadly. We believe that the integration of feminist currents to the environmental care proposed by conservation biology can result in valuable contributions and in disruptive approaches with respect to the hegemonic view of natural sciences. These "new insights" may allow for a better social appropriation in conservation projects, by overcoming problematic assumptions -linked to the current environmental crisis- such as the nature-culture dualism, and considering different socio-environmental aspects regarding biodiversity loss.Este artículo de reflexión pretende realizar una breve introducción al llamado ecofeminismo, con el objetivo de visibilizar sus encuentros y diferencias con las propuestas de la biología de la conservación. Propondremos que el ecofeminismo tiene numerosos aportes epistemológicos y ético-políticos que pueden enriquecer a las prácticas de la biología de la conservación y generar una mirada crítica sobre el rol de las ciencias en las problemáticas ambientales. Para ello examinaremos dos elementos de análisis, particularmente relevantes para el ecofeminismo. El primero refiere a la noción de naturaleza en la modernidad y la perspectiva dualista que separa naturaleza de cultura. El segundo refiere a la epistemología tradicional de las ciencias naturales, vinculado a la idea de objetividad y neutralidad, así como en relación con el rol asignado a las ciencias naturales frente a las problemáticas ambientales. Posteriormente, contrastaremos dichas críticas con los discursos de la biología de la conservación, tratando de examinar en qué medida se reproducen los presupuestos criticados por el ecofeminismo y en qué medida aparecen búsquedas comunes. Nuestro análisis indica que en cierta medida algunos elementos del ecofeminismo parecen encontrar resonancias y perspectivas comunes en la biología de la conservación, más no de modo amplio. Creemos que las alianzas entre las corrientes feministas y las de cuidado ambiental, propuestas por la biología de la conservación, pueden resultar aproximaciones disruptivas respecto de la mirada hegemónica de las ciencias naturales. Estas “nuevas miradas” tal vez posibiliten una mayor apropiación social en los proyectos de conservación, que no reproduzcan supuestos problemáticos –vinculados a la actual crisis ambiental- como el dualismo naturaleza-cultura y que consideren diferentes aristas socioambientales respecto de la pérdida de biodiversidad

Selective methane oxidation over promoted oxide catalysts. Topical report, September 8, 1992--September 7, 1996

The objective of this research was to selectively oxidize methane to C{sub 2} hydrocarbons and to oxygenates, in particular formaldehyde and methanol, in high space time yields using air at the oxidant under milder reaction conditions that heretofore employed over industrially practical oxide catalysts. The research carried out under this US DOE-METC contract was divided into the following three tasks: Task 1, maximizing selective methane oxidation to C{sub 2}{sup +} products over promoted SrO/La{sub 2}O{sub 3} catalysts; Task 2, selective methane oxidation to oxygenates; and Task 3, catalyst characterization and optimization. Principal accomplishments include the following: the 1 wt% SO{sub 4}{sup 2{minus}}/SrO/La{sub 2}O{sub 3} promoted catalyst developed here produced over 2 kg of C{sub 2} hydrocarbons/kg catalyst/hr at 550 C; V{sub 2}O{sub 5}/SiO{sub 2} catalysts have been prepared that produce up to 1.5 kg formaldehyde/kg catalyst/hr at 630 C with low CO{sub 2} selectivities; and a novel dual bed catalyst system has been designed and utilized to produce over 100 g methanol/kg catalyst/hr at 600 C with the presence of steam in the reactant mixture

A low power photoemission source for electrons on liquid helium

Electrons on the surface of liquid helium are a widely studied system that may also provide a promising method to implement a quantum computer. One experimental challenge in these studies is to generate electrons on the helium surface in a reliable manner without heating the cryo-system. An electron source relying on photoemission from a zinc film has been previously described using a high power continuous light source that heated the low temperature system. This work has been reproduced more compactly by using a low power pulsed lamp that avoids any heating. About 5e3 electrons are collected on 1 cm^2 of helium surface for every pulse of light. A time-resolved experiment suggests that electrons are either emitted over or tunnel through the 1eV barrier formed by the thin superfluid helium film on the zinc surface. No evidence of trapping or bubble formation is seen.Comment: 9 pages, 3 figures, submitted to J. Low Temp. Phy

Nanoparticulate CpG Immunotherapy in RAO- Affected Horses: Phase I and IIa Study

Background: Recurrent airway obstruction (RAO), an asthma-like disease, is 1 of the most common allergic diseases in horses in the northern hemisphere. Hypersensitivity reactions to environmental antigens cause an allergic inflammatory response in the equine airways. Cytosine-phosphate-guanosine-oligodeoxynucleotides (CpG-ODN) are known to direct the immune system toward a Th1-pathway, and away from the pro-allergic Th2-line (Th2/Th1-shift). Gelatin nanoparticles (GNPs) are biocompatible and biodegradable immunological inert drug delivery systems that protect CpG-ODN against nuclease degeneration. Preliminary studies on the inhalation of GNP-bound CpG-ODN in RAO-affected horses have shown promising results. Objectives: The aim of this study was to evaluate the clinical and immunological effects of GNP-bound CpG-ODN in a double-blinded, placebo-controlled, prospective, randomized clinical trial and to verify a sustained effect post-treatment. Animals and Methods: Twenty-four RAO-affected horses received 1 inhalation every 2 days for 5 consecutive administrations. Horses were examined for clinical, endoscopic, cytological, and blood biochemical variables before the inhalation regimen (I), immediately afterwards (II), and 4 weeks post-treatment (III). Results: At time points I and II, administration of treatment rather than placebo corresponded to a statistically significant decrease in respiratory effort, nasal discharge, tracheal secretion, and viscosity, AaDO2 and neutrophil percentage, and an increase in arterial oxygen pressure. Conclusion and Clinical Importance: Administration of a GNP-bound CpG-ODN formulation caused a potent and persistent effect on allergic and inflammatory-induced clinical variables in RAO-affected horses. This treatment, therefore, provides an innovative, promising, and well-tolerated strategy beyond conventional symptomatic long-term therapy and could serve as a model for asthma treatment in humans

Selective Methane Oxidation Over Promoted Oxide Catalysts. Quarterly Report, September 1 - November 30, 1995

The objective of this research is the selective oxidation of methane to C{sub 2}H{sub 4} hydrocarbons and to oxygenates, in particular formaldehyde and methanol. Air, oxygen, or carbon dioxide rather than nitrous oxide, are utilized as the oxidizing gas at high gas hourly space velocity but mild reaction conditions (500-700{degrees}C, 1 atm total pressure). All the investigated processes are catalytic, aiming at minimizing gas phase reactions that are difficult to control. During this quarter, solid state {sup 51}V NMR and double catalyst bed experiments were conducted to demonstrate the unfavorable effect of the presence of bulk crystalline V{sub 2}O{sub 5} in V{sub 2}O{sub 5}-SiO{sub 2} xerogel catalysts on selective oxidation of methane to methanol and formaldehyde. Results are discussed

Selective methane oxidation over promoted oxide catalysts. Quarterly report, June 1 - August 31, 1996

Further data analysis for the conversion of methane to oxygenates over high surface are V{sub 2}O{sub 5}/SiO{sub 2} xerogel catalysts that were synthesized by a sol-gel process have been carried out. As previously described the vanadia loading of the catalysts was varied between 0-25 wt%. Turnover numbers (T.O.N.) have been calculated for methane conversion to products and for the synthesis of methanol and formaldehyde, where T.O.N. is defined as molecules converted or formed per dispersed tetrahedrally coordinated vanadium atom ad determined by {sup 51}V NMR analyses. It is found that highly dispersed tetrahedrally coordinated V{sup 5+} is the active site for the selective conversion of methane to methanol and formaldehyde

The RFOFO Ionization Cooling Ring for Muons

Practical ionization cooling rings could lead to lower cost or improved performance in neutrino factory or muon collider designs. The ring modeled here uses realistic three-dimensional fields. The performance of the ring compares favorably with the linear cooling channel used in the second US Neutrino Factory Study. The normalized 6D emittance of an ideal ring is decreased by a factor of approximately 240, compared with a factor of only 15 for the linear channel. We also examine such \textit{real-world} effects as windows on the absorbers and rf cavities and leaving empty lattice cells for injection and extraction. For realistic conditions the ring decreases the normalized 6D emittance by a factor of 49.Comment: 27 pages, 18 figures and 5 tables. Submitted to Phys. Rev. ST-A