Analysis Of Service Failures.

LecturePg. 75-86When a component fails prematurely, it is most important that an engineering evaluation be made of the loss. If one is alert enough to learn from past problems then "Experience gained is directly proportional to equipment ruined, "provided the true cause is determined. A comprehensive failure analysis will enable the engineer to predict future problems, establish inspection criteria and intervals, improve safety, refine operating procedures and correct equipment specifications. The ultimate goal of all of this effort should be a reduction in maintenance expense and improvement in equipment on-stream time. In most cases, only the materials oriented engineer is involved in the analysis of service failures, since it is always presumed that the material of construction is "guilty until proven innocent." Unfortunately, this approach can lead to a somewhat biased and incomplete result, and in many cases, does not find either the true cause or an acceptable long term fix. The necessary requirements of a comprehensive failure analysis using "real world" examples are presented

Nondestructive Testing of Turbomachinery Components

SealsPg. 161-166Nondestructive evaluation is becoming increasingly important in determining the quality of materials and fabrications used in the manufacture and maintenance of rotating machinery. NDE has long been used as a tool for failure analysis. However, more and more techniques are being incorporated as required steps in manufacturing to ensure defect-free parts. NDE can be defined as a science that incorporates methods of detecting and measuring the major properties and performance capabilities of materials, parts, assemblies, equipment and structures using techniques that do not impair serviceability. NDE uses a variety of probing techniques to assist in the discovery of hidden faults and properties of materials and products. Since most of the techniques used in nondestructive evaluation are based on well-established principles, the proper choice and application of the correct method or methods will determine the final usefulness of the examination. Each of these common classical "Big Five" NDE techniques are reviewed along with their capabilities and shortcomings. In addition, some of the more recent developments in evaluation methods are presented

Some Thoughts On Avoiding Metallurgical Failures.

Tutorialpg. 203-208Predicting potential problems that will ultimately lead to premature material related failures and implementing the necessary corrections during design, fabrication, and commissioning has long been recognized by some as the most cost effective means of improving equipment performance. Unfortunately, the technology and experience that are needed to recognize problems and provide solutions can only be gained by being exposed to and analyzing prior deficiencies and failures. In short, "Information gained is directly proportional to equipment ruined." Examples of environment-material interaction, improper material selection, incorrect processing, design considerations, and improper installation/maintenance will all be examined as they relate to avoiding failures

Practical Approach To Understanding Steels, Their Alloying, Heat Treatment And Surface Hardening

Tutorialpg. 103-112The greatest tonnage of engineering materials used in the world are steels. Therefore, it is most helpful, and in many cases mandatory, that those who either design, fabricate or maintain components constructed of steel have a practical understanding of how this family of materials functions. Steel is a very versatile material which can exhibit a wide range of both physical and mechanical characteristics. The diversity of steel is never more strikingly illustrated than the use of a file to round off a rough edge or a steel cutting tool to shape another piece of steel in some form of metal working equipment. These are two pieces of the same metal so different in properties that one, without damage to itself, will actually cut the other. The addition of various alloying elements to steel and how they affect the efficiency of thermal heat treatment, mechanical properties, dimensional stability, fatigue properties, wear and machinability will be discussed. In addition, all of the commonly used through section heat treating processes are described as they apply to steel and its alloys. The two major classes of surface hardening techniques, namely alterations to and no alternations of the surface chemistry, will be discussed as they apply to increasing hardness, improving wear and fatigue resistance and controlling dimensional stability of mechanical components

Passive microfluidic chamber for long-term imaging of axon guidance in response to soluble gradients

A user-friendly microfluidic chamber produces a passive, stable gradient of soluble cues for imaging and quantification of axon turning

Trim9 Deletion Alters the Morphogenesis of Developing and Adult-Born Hippocampal Neurons and Impairs Spatial Learning and Memory

During hippocampal development, newly born neurons migrate to appropriate destinations, extend axons, and ramify dendritic arbors to establish functional circuitry. These developmental stages are recapitulated in the dentate gyrus of the adult hippocampus, where neurons are continuously generated and subsequently incorporate into existing, local circuitry. Here we demonstrate that the E3 ubiquitin ligase TRIM9 regulates these developmental stages in embryonic and adult-born mouse hippocampal neurons in vitro and in vivo. Embryonic hippocampal and adult-born dentate granule neurons lacking Trim9 exhibit several morphological defects, including excessive dendritic arborization. Although gross anatomy of the hippocampus was not detectably altered by Trim9 deletion, a significant number of Trim9−/− adult-born dentate neurons localized inappropriately. These morphological and localization defects of hippocampal neurons in Trim9−/− mice were associated with extreme deficits in spatial learning and memory, suggesting that TRIM9-directed neuronal morphogenesis may be involved in hippocampal-dependent behaviors

Multi-monoubiquitylation controls VASP-mediated actin dynamics Icon for The Forest of Biologists

The actin cytoskeleton performs multiple cellular functions, and as such, actin polymerization must be tightly regulated. We previously demonstrated that reversible, non-degradative ubiquitylation regulates the function of the actin polymerase VASP in developing neurons. However, the underlying mechanism of how ubiquitylation impacts VASP activity was unknown. Here, we show that mimicking multi-monoubiquitylation of VASP at K240 and K286 negatively regulates VASP interactions with actin. Using in vitro biochemical assays, we demonstrate the reduced ability of multi-monoubiquitylated VASP to bind, bundle, and elongate actin filaments. However, multi-monoubiquitylated VASP maintained the ability to bind and protect barbed ends from capping protein. Finally, we demonstrate the electroporation of recombinant multi-monoubiquitylated VASP protein altered cell spreading morphology. Collectively, these results suggest a mechanism in which ubiquitylation controls VASP-mediated actin dynamics

The Cytotoxicity and Mode of Action of 2,3,4-Trisubstituted Pyrroles and Related Derivatives in Human Tmolt4 Leukemia Cells

4-Carbechoxy-l-methyl-2-phenacyl-3-phenylpyrrole (9), 4-carbethoxy-2-(4-methoxybcnzoyl)-3-(4-methoxyphcnyl)pyrrole (10) and 2-(4-methoxybenzoyl)-3,4-bis-(4-methoxyphenyl)pyrrole (11) proved to be potent cytotoxic agents against the growth of murine and human leukemias and lymphomas. Selective toxicity was demonstrated against the growth of solid tumors, e.g. human adenocarcinoma of the colon SW480 and ileum HCT-8, glioma U-87-MG, and rat UMR-106 osteosarcoma. A mode of action study in Tmolt4 leukemia cells demonstrated that the agents inhibited de novo purine synthesis at the regulatory sites PRPP-amido transferase, IMP dehydrogenase as well as dihydrofolate reductase resulting in significant inhibition of DNA synthesis in 60 min. Other biochemical sites which were affected significantly were thymidylate synthetase, DNA polymerase a, RNA polymerases, nucleoside kinase and ribonucleoside reductase

A novel Netrin-1-sensitive mechanism promotes local SNARE-mediated exocytosis during axon branching

Developmental axon branching dramatically increases synaptic capacity and neuronal surface area. Netrin-1 promotes branching and synaptogenesis, but the mechanism by which Netrin-1 stimulates plasma membrane expansion is unknown. We demonstrate that SNARE-mediated exocytosis is a prerequisite for axon branching and identify the E3 ubiquitin ligase TRIM9 as a critical catalytic link between Netrin-1 and exocytic SNARE machinery in murine cortical neurons. TRIM9 ligase activity promotes SNARE-mediated vesicle fusion and axon branching in a Netrin-dependent manner. We identified a direct interaction between TRIM9 and the Netrin-1 receptor DCC as well as a Netrin-1–sensitive interaction between TRIM9 and the SNARE component SNAP25. The interaction with SNAP25 negatively regulates SNARE-mediated exocytosis and axon branching in the absence of Netrin-1. Deletion of TRIM9 elevated exocytosis in vitro and increased axon branching in vitro and in vivo. Our data provide a novel model for the spatial regulation of axon branching by Netrin-1, in which localized plasma membrane expansion occurs via TRIM9-dependent regulation of SNARE-mediated vesicle fusion.American Heart Association (Fellowship 0615692T)National Institutes of Health (U.S.) (Grant GM68678

A Cross-Sectional Study of People with Epilepsy and Neurocysticercosis in Tanzania: Clinical Characteristics and Diagnostic Approaches.

Neurocysticercosis (NCC) is a major cause of epilepsy in regions where pigs are free-ranging and hygiene is poor. Pork production is expected to increase in the next decade in sub-Saharan Africa, hence NCC will likely become more prevalent. In this study, people with epilepsy (PWE, n=212) were followed up 28.6 months after diagnosis of epilepsy. CT scans were performed, and serum and cerebrospinal fluid (CSF) of selected PWE were analysed. We compared the demographic data, clinical characteristics, and associated risk factors of PWE with and without NCC. PWE with NCC (n=35) were more likely to be older at first seizure (24.3 vs. 16.3 years, p=0.097), consumed more pork (97.1% vs. 73.6%, p=0.001), and were more often a member of the Iraqw tribe (94.3% vs. 67.8%, p=0.005) than PWE without NCC (n=177). PWE and NCC who were compliant with anti-epileptic medications had a significantly higher reduction of seizures (98.6% vs. 89.2%, p=0.046). Other characteristics such as gender, seizure frequency, compliance, past medical history, close contact with pigs, use of latrines and family history of seizures did not differ significantly between the two groups. The number of NCC lesions and active NCC lesions were significantly associated with a positive antibody result. The electroimmunotransfer blot, developed by the Centers for Disease Control and Prevention, was more sensitive than a commercial western blot, especially in PWE and cerebral calcifications. This is the first study to systematically compare the clinical characteristics of PWE due to NCC or other causes and to explore the utility of two different antibody tests for diagnosis of NCC in sub-Saharan Africa