Fractography of the high temperature hydrogen attack of a medium carbon steel

Microscopic fracture processes were studied which are associated with hydrogen attack of a medium carbon steel in a well-controlled, high-temperature, high-purity hydrogen environment. Exposure to a hydrogen pressure and temperature of 3.5 MN/m2 and 575 C was found to degrade room temperature tensile properties with increasing exposure time. After 408 hr, yield and ultimate strengths were reduced by more than 40 percent and elongation was reduced to less than 2 percent. Initial fissure formation was found to be associated with manganese rich particles, most probably manganese oxide, aligned in the microstructure during the rolling operation. Fissure growth was found to be associated with a reduction in carbide content of the microstructure and was inhibited by the depletion of carbon. The interior surfaces of sectioned fissures or bubbles exhibit both primary and secondary cracking by intergranular separation. The grain surfaces were rough and rounded, suggesting a diffusion-associated separation process. Specimens that failed at room temperature after exposure to hydrogen were found to exhibit mixed mode fracture having varying amounts of intergranular separation, dimple formation, and cleavage, depending on exposure time

Wind Tunnel Aerodynamic Characteristics of a Transport-type Airfoil in a Simulated Heavy Rain Environment

The effects of simulated heavy rain on the aerodynamic characteristics of an NACA 64-210 airfoil section equipped with leading-and trailing-edge high-lift devices were investigated in the Langley 14- by 22-Foot Subsonic Tunnel. The model had a chord of 2.5 ft, a span of 8 ft, and was mounted on the tunnel centerline between two large endplates. Aerodynamic measurements in and out of the simulated rain environment were obtained for dynamic pressures of 30 and 50 psf and an angle-of-attack range of 0 to 20 degrees for the cruise configuration. The rain intensity was varied to produce liquid water contents ranging from 16 to 46 gm/cu m. The results obtained for various rain intensity levels and tunnel speeds showed significant losses in maximum lift capability and increases in drag for a given lift as the liquid water content was increased. The results obtained on the landing configuration also indicate a progressive decrease in the angle of attack at which maximum lift occurred and an increase in the slope of the pitching-moment curve as the liquid water content was increased. The sensitivity of test results to the effects of the water surface tension was also investigated. A chemical was introduced into the rain environment that reduced the surface tension of water by a factor of 2. The reduction in the surface tension of water did not significantly alter the level of performance losses for the landing configuration

Oat Grain Variety Trial at Overton for 2000-2001 and Three Year Means

Last updated: 6/12/200

Bioterrorism, Biodefense, and Biotechnology in the Military: A Comparative Analysis of Legal and Ethical Issues in the Research, Development, and Use of Biotechnological Products on American and British Soldiers.

Despite the legal and ethical concerns raised, biotechnology continues to offer countless opportunities for enhancing military capabilities. As such, the research, development and utilization of biotechnological products are present realities in the U.S. and abroad, both within and outside of the defense context. However, testing and usage, as well as effective collaboration between Allies, calls for the resolution of complex and pressing issues presented by this intersection of science, technology, and human lives. Resolutions must take into account the history of abuses in military research, existing domestic and international legal and ethical safeguards, and a special respect for those serving to protect their country

Heavy rain effects on airplane performance

The objective is to determine if the aerodynamic characteristics of an airplane are altered while flying in the rain. Wind-tunnel tests conducted at the NASA Langley Research Center (LaRC) have shown losses in maximum lift, reduction in stall angle, and increases in drag when a wing is placed in a simulated rain spray. For these tests the water spray concentration used represented a very heavy rainfall. A lack of definition of the scaling laws for aerodynamic testing in a two-phase, two-component flow makes interpolation of the wind-tunnel test uncertain. Tests of a large-scale wing are to be conducted at the LaRC. The large-scale wing is mounted on top of the Aircraft Landing Dynamics Facility (ALDF) carriage. This carriage (which is 70-foot long, 30-foot wide, and 30-foot high) is propelled with the wing model attached down a 3000-foot long test track by a water jet at speeds of up to 170 knots. A simulated rain spray system has been installed along 500 feet of the test track and can simulate rain falls from 2 to 40 inches/hour. Operational checks are underway and the initial tests should be completed by the Fall of 1989

Flowering of emerald sweetclover in Texas

Last updated: 6/1/200

Biliary and pancreatic lithotripsy devices

© 2018 Background and Aims: Lithotripsy is a procedure for fragmentation or destruction of stones to facilitate their removal or passage from the biliary or pancreatic ducts. Although most stones may be removed endoscopically using conventional techniques such as endoscopic sphincterotomy in combination with balloon or basket extraction, lithotripsy may be required for clearance of large, impacted, or irregularly shaped stones. Several modalities have been described, including intracorporeal techniques such as mechanical lithotripsy (ML), electrohydraulic lithotripsy (EHL), and laser lithotripsy, as well as extracorporeal shock-wave lithotripsy (ESWL). Methods: In this document, we review devices and methods for biliary and pancreatic lithotripsy and the evidence regarding efficacy, safety, and financial considerations. Results: Although many difficult stones can be safely removed using ML, endoscopic papillary balloon dilation (EPBD) has emerged as an alternative that may lessen the need for ML and also reduce the rate of adverse events. EHL and laser lithotripsy are effective at ductal clearance when conventional techniques are unsuccessful, although they usually require direct visualization of the stone by the use of cholangiopancreatoscopy and are often limited to referral centers. ESWL is effective but often requires coordination with urologists and the placement of stents or drains with subsequent procedures for extracting stone fragments and, thus, may be associated with increased costs. Conclusions: Several lithotripsy techniques have been described that vary with respect to ease of use, generalizability, and cost. Overall, lithotripsy is a safe and effective treatment for difficult biliary and pancreatic duct stones

Children\u27s experiences of companion animal maltreatment in households characterized by intimate partner violence

Cruelty toward companion animals is a well-documented, coercive tactic used by abusive partners to intimidate and control their intimate partners. Experiences of co-occurring violence are common for children living in families with intimate partner violence (IPV) and surveys show that more than half are also exposed to abuse of their pets. Given children\u27s relationships with their pets, witnessing such abuse may be traumatic for them. Yet little is known about the prevalence and significance of this issue for children. The present study examines the experiences of children in families with co-occurring pet abuse and IPV. Using qualitative methods, 58 children ages 7–12 who were exposed to IPV were asked to describe their experiences of threats to and harm of their companion animals. Following the interviews, template analysis was employed to systematically develop codes and themes. Coding reliability was assessed using Randolph\u27s free-marginal multirater kappa (kfree = .90). Five themes emerged from the qualitative data, the most common being children\u27s exposure to pet abuse as a power and control tactic against their mother in the context of IPV. Other themes were animal maltreatment to discipline or punish the pet, animal cruelty by a sibling, children intervening to prevent pet abuse, and children intervening to protect the pet during a violent episode. Results indicate that children\u27s experiences of pet abuse are multifaceted, potentially traumatic, and may involve multiple family members with diverse motives

Changes in behavioural synchrony during dog-assisted therapy for children with autism spectrum disorder and children with Down syndrome

BACKGROUND: Dog-assisted therapy (DAT) is hypothesized to help children with autism spectrum disorder (ASD) and Down syndrome (DS). METHODS: The present authors compared synchronous movement patterns of these children (n = 10) and their therapy dogs during the first and last session of a DAT programme, and their post-therapy changes in emotional and behavioural problems. RESULTS: The present authors found a significant increase in synchrony between child and therapy dog over time. Exploratory analyses suggest more synchrony between children with ASD and their therapy dogs, compared to the children with DS. CONCLUSIONS: This study is the first to test the synchrony hypothesis, shedding light upon a mechanism that may underlie the effect of DAT and how this may be different for children with ASD and DS