Stress corrosion resistant fasteners

A family of high performance aerospace fasteners made from corrosion resistant alloys for use in applications where corrosion and stress-corrosion cracking are of major concern are discussed. The materials discussed are mainly A-286, Inconel 718, MP35N and MP159. Most of the fasteners utilize cold worked and aged materials to achieve the desired properties. The fasteners are unique in that they provide a combination of high strength and immunity to stress corrosion cracking not previously attainable. A discussion of fastener stress corrosion failures is presented including a review of the history and a description of the mechanism. Case histories are presented to illustrate the problems which can arise when material selection is made without proper regard for the environmental conditions. Mechanical properties and chemical compositions are included for the fasteners discussed. Several aspects of the application of high performance corrosion resistant fasteners are discussed including galvanic compatibility and torque-tension relationships

Extracellular production of reactive oxygen species in response to abiotic stress in seeds

Reactive oxygen species (ROS), such as superoxide (O2 •‾), hydrogen peroxide (H2O2), singlet oxygen (1O2) and the hydroxyl radical (•OH) can damage essential biomolecules including nucleic acids, proteins and lipids, causing damage to various cellular components. However, ROS also participate in signalling networks that are essential in plant stress responses, and also in the regulation of growth and development. Given the apparent importance of ROS, it is surprising that very little of their beneficial aspects have been researched in seeds and seedlings. Using desiccation sensitive ("recalcitrant") seeds of sweet chestnut (Castanea sativa Mill.) and desiccation tolerant ("orthodox") seeds of garden pea (Pisum sativum L.), the production of ROS was investigated during germination and seedling development, and in response to abiotic stress. Putative extracellular ROS-producing enzymes in both species were characterised to elucidate mechanisms of ROS production. Desiccating C. sativa seeds led to viability loss while the intracellular antioxidant glutathione became increasingly oxidised. Wounding and desiccation induced extracellular ROS production in C. sativa embryonic axes and P. sativum seedling axes. A pivotal role for extracellular peroxidases in producing O2 •‾ as a stress response became evident in both species as well as for the development of P. sativum seedlings. Wounding also induced amine oxidases in P. sativum embryonic axes to produce a burst of H2O2 that was essential for O2 •‾ production. Lipoxygenases were identified as putative O2 •‾- producing enzymes that may contribute to stress signalling in response to wounding. Treating desiccation-stressed material with H2O2 improved seed germination, seedling vigour and the establishment of secondary root growth. In conclusion, cell wall peroxidases, amine oxidases and lipoxygenases may work in synergy to produce O2 •‾required for stress signalling. Such extracellular ROS produced by seeds appear to be important signalling components involved in wound and desiccation response, regeneration and growth

Contracts—Agreements Not to Compete—Powers of Equity to Scale Down Unreasonable Terms

Thomas v. Paker, __ Mass __, 98 N. E. 640 (1951)

Admiralty—Contribution Denied in Non-Collision Case

Baccile v. Halcyon Lines, (187 F. 2d 403 3rd Cir. 1951)

A study of ASRS reports involving general aviation and weather encounters

Consideration is given to the nature and characteristics of problems involving dissemination of weather information, use of this information by pilots, its adequacy for the purpose intended, the ability of the air traffic control system to cope with weather related incidents, and the various aspects of pilot behavior, aircraft equipment, and NAVAIDS affecting flights in which weather figures. It is concluded from the study that skill and training deficiencies of general aviation pilots are not major factors in weather related occurrences, nor is lack of aircraft equipment. Major problem causes are identified with timely and easily interpreted weather information, judgement and attitude factors of pilots, and the functioning of the air traffic control system

Relaxation Design of Separable Tube Connectors

Design procedure to predict relaxation or time to leakage for separable tube connector

A resilience-based methodology for improved water resources adaptation planning under deep uncertainty with real world application

This is the author accepted manuscript. The final version is available from Springer Verlag via the DOI on this record.Resilience of a water resource system in terms of water supply meeting future demand under climate change and other uncertainties is a prominent issue worldwide. This paper presents an alternative methodology to the conventional engineering practice in the UK for identifying long term adaptation planning strategies in the context of resilience. More specifically, a resilience based multi-objective optimization method is proposed that identifies Pareto optimal future adaptation strategies by maximizing a water supply system’s resilience (calculated as the maximum recorded duration of a water deficit period over a given planning horizon) and minimizing total associated costs, subject to meeting target system robustness to uncertain projections (scenarios) of future supply and demand. The method is applied to a real-world case study for Bristol Water’s water resource zone and the results are compared with those derived using a more conventional engineering practice in the UK, utilizing a least-cost optimization analysis constrained to a target reliability level. The results obtained reveal that the strategy solution derived using the current practice methodology produce a less resilient system than the similar costing solutions identified using the proposed resilience driven methodology. At the same time, resilience driven strategies are only slightly less reliable suggesting that trade-off exists between the two. Further examination of intervention strategies selected shows that the conventional methodology encourages implementation of more lower cost intervention options early in the planning horizon (to achieve higher system reliability) whereas the resilience-based methodology encourages more uniform intervention options sequenced over the planning horizon (to achieve higher system resilience).This work was financially supported by the UK Engineering and Physical Sciences Research Council, HR Wallingford and The University of Exeter through the STREAM Industrial Doctorate Centre. We thank Bristol Water for allowing the use of their data and information, which is available from their publicly available water resources management plan

Tensin1 expression and function in chronic obstructive pulmonary disease

open access articleChronic obstructive pulmonary disease (COPD) constitutes a major cause of morbidity and mortality. Genome wide association studies have shown significant associations between airflow obstruction or COPD with a non-synonymous SNP in the TNS1 gene, which encodes tensin1. However, the expression, cellular distribution and function of tensin1 in human airway tissue and cells are unknown. We therefore examined these characteristics in tissue and cells from controls and people with COPD or asthma. Airway tissue was immunostained for tensin1. Tensin1 expression in cultured human airway smooth muscle cells (HASMCs) was evaluated using qRT-PCR, western blotting and immunofluorescent staining. siRNAs were used to downregulate tensin1 expression. Tensin1 expression was increased in the airway smooth muscle and lamina propria in COPD tissue, but not asthma, when compared to controls. Tensin1 was expressed in HASMCs and upregulated by TGFβ1. TGFβ1 and fibronectin increased the localisation of tensin1 to fibrillar adhesions. Tensin1 and α-smooth muscle actin (αSMA) were strongly co-localised, and tensin1 depletion in HASMCs attenuated both αSMA expression and contraction of collagen gels. In summary, tensin1 expression is increased in COPD airways, and may promote airway obstruction by enhancing the expression of contractile proteins and their localisation to stress fibres in HASMCs

Comparison of robust optimization and info-gap methods for water resource management under deep uncertainty

This is the author accepted manuscript. The final version is available from the publisher via the DOI in this record.This paper evaluates two established decision-making methods and analyzes their performance and suitability within a water resources management (WRM) problem. The methods under assessment are info-gap (IG) decision theory and robust optimization (RO). The methods have been selected primarily to investigate a contrasting local versus global method of assessing water system robustness to deep uncertainty, but also to compare a robustness model approach (IG) with a robustness algorithm approach (RO), whereby the former selects and analyzes a set of prespecified strategies and the latter uses optimization algorithms to automatically generate and evaluate solutions. The study presents a novel area-based method for IG robustness modeling and assesses the applicability of utilizing the future flows climate change projections in scenario generation for water resource adaptation planning. The methods were applied to a case study resembling the Sussex North Water Resource Zone in England, assessing their applicability at improving a risk-based WRM problem and highlighting the strengths and weaknesses of each method at selecting suitable adaptation strategies under climate change and future demand uncertainties. Pareto sets of robustness to cost are produced for both methods and highlight RO as producing the lower cost strategies for the full range of varying target robustness levels. IG produced the more expensive Pareto strategies due to its more selective and stringent robustness analysis, resulting from the more complex scenario ordering process.This work was financially supported by the UK Engineering and Physical Sciences Research Council, HR Wallingford and The University of Exeter through the STREAM Industrial Doctorate Centre. The authors are grateful to Dr Steven Wade, now at the Met Office, and Chris Counsell of HR Wallingford for providing data for the Sussex North case study

Low-cycle fatigue of Type 347 stainless steel and Hastelloy alloy X in hydrogen gas and in air at elevated temperatures

An investigation was conducted to assess the low-cycle fatigue resistance of two alloys, Type 347 stainless steel and Hastelloy Alloy X, that were under consideration for use in nuclear-powered rocket vehicles. Constant-amplitude, strain-controlled fatigue tests were conducted under compressive strain cycling at a constant strain rate of 0.001/sec and at total axial strain ranges of 1.5, 3.0, and 5.0 %, in both laboratory-air and low-pressure hydrogen-gas environments at temperatures from 538 to 871 C. Specimens were obtained from three heats of Type 347 stainless steel bar and two heats of Hastelloy Alloy X. The tensile properties of each heat were determined at 21, 538, 649, and 760 C. The continuous cycling fatigue resistance was determined for each heat at temperatures of 538, 760, and 871 C. The Type 347 stainless steel exhibited equal or superior fatigue resistance to the Hastelloy Alloy X at all conditions of this study