Design, Fabrication and Test of Composite Curved Frames for Helicopter Fuselage Structure

Aspects of curved beam effects and their importance in designing composite frame structures are discussed. The curved beam effect induces radial flange loadings which in turn causes flange curling. This curling increases the axial flange stresses and induces transverse bending. These effects are more important in composite structures due to their general inability to redistribute stresses by general yielding, such as in metal structures. A detailed finite element analysis was conducted and used in the design of composite curved frame specimens. Five specimens were statically tested and compared with predicted and test strains. The curved frame effects must be accurately accounted for to avoid premature fracture; finite element methods can accurately predict most of the stresses and no elastic relief from curved beam effects occurred in the composite frames tested. Finite element studies are presented for comparative curved beam effects on composite and metal frames

Vegetative Nuclear Division In Neurospora

Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/141698/1/ajb210695.pd

Where is the Theoretical Basis for Understanding and Measuring the Environment for Physical Activity?

Researchers are beginning to explore environmental correlates to further the field of physical activity research. Before interventions and experimental investigations can be undertaken, it is necessary to identify specific environmental features that are consistent correlates of physical activity. There has been a plethora of research measuring such cross-sectional associations since this field came to the fore in 2003. This paper posits that it is time for researchers to evaluate the state of knowledge, and suggests that future developments in this field focus on the theoretical bases for (i) measurement of the environment and (ii) understanding the links between perceptions of the environment and behaviour through psychological theories of cognition. Key theories considered include social ecology and the theory of planned behaviour. It is suggested that with a continued absence of a common conceptual framework, vocabulary and measurement tools the majority of studies may remain at a correlates stage. In highlighting issues with current methodologies, this commentary encourages more grounded theoretical approaches to the study of the environment and physical activity

Interactions of asbestos-activated macrophages with an experimental fibrosarcoma

Supernatants from in vivo asbestos-activated macrophages failed to show any cytostatic activity against a syngeneic fibrosarcoma cell line in vitro. UICC chrysotile-induced peritoneal exudate cells also failed to demonstrate any growth inhibitory effect on the same cells in Winn assays of tumor growth. Mixing UICC crocidolite with inoculated tumor cells resulted in a dose-dependent inhibition of tumor growth; this could, however, be explained by a direct cytostatic effect on the tumor cells of high doses of crocidolite, which was observed in vitro

POLYCHLORINATED BIPHENYL COMPLIANCE ISSUES IN THE 21ST CENTURY: POORLY RECOGNIZED AND POTENTIALLY DEVASTATING-8162

Thirty-one years have passed since the United States Congress passed the Toxic Substances Control Act (TSCA) [1]. The 1976 law essentially eliminated future production of polychlorinated biphenyls (PCBs) within the United States and greatly limited the use of previously manufactured PCBs and PCB products. The ultimate objective of the law was the complete elimination of these chemicals due to concerns about their potentially toxic effects on health and the environment. PCBs were manufactured in the United States between 1929 and 1977. They were highly valued for their fire and heat-resistance properties and for their chemical stability. As a result, PCBs were used in a variety of thermally and/or chemically stressful applications. They did not conduct electricity and therefore were particularly well-suited for use as insulating fluids in high-voltage electric equipment. PCBs were also used in various other applications, such as in hydraulic and heat transfer fluids. Strict controls on the use and disposal of PCBs were imposed by the TSCA implementing regulations at 40 CFR 761 [2]. As a result, most heavy users of PCB products worked hard to curtail their PCB use. Many organizations that once used substantial amounts of PCBs, subsequently declared themselves ''PCB free''. Unfortunately, in many cases, these ''PCB-free'' declarations were premature, as PCBs were used in many more applications than insulating fluids. From the 1990s and to the present day, PCBs increasingly have been discovered in non-liquid forms. These materials were used or installed in facilities constructed before the 1979 ''PCB ban''. Examples include applied paints and coatings, caulking, pre-formed joint filler, and plastic or rubber wire and cable insulation. Proper identification of these materials is necessary for appropriate and compliant waste management during decommissioning and deactivation (D&D) activities. PCBs can pose other significant waste management issues for D&D projects, particularly for nuclear facilities. Depending upon the waste form and the intended disposal path, PCBs can be regulated at thresholds in the low parts-per-billion (ppb). These low regulatory thresholds often are overlooked due to the erroneous belief by many waste management professionals that materials containing PCBs are regulated by TSCA only if their PCB concentration is at least 50 parts-per-million (ppm). Failure to recognize when and how the lower thresholds apply can lead to rejection of the waste materials by treatment, storage and disposal (TSD) facilities as well as potential regulatory non-compliance. Furthermore, re-use of ''excess'' materials with PCBs is also regulated by TSCA. In the event of a characterization error, the costs required to make necessary corrections can be very high. This paper will focus on PCB characterization and waste management issues associated with D&D of DOE nuclear facilities. It will identify PCB materials that are likely to be present in such facilities, with emphasis on the nonliquid PCB forms. The paper will discuss characterization pitfalls associated with Non-Liquid PCBs (NLPCBs), including circumstances in which NLPCBs can migrate into other materials. The paper also will identify TSCA requirements for materials with very low concentrations of PCBs; certain materials are regulated at concentrations as low as 0.5 {micro}g/L PCBs (approximately 0.5 ppb). The paper will then examine the potentially extensive impacts to a facility if the materials are not managed in a TSCA-compliant manner. Examples from a recent D&D project at the DOE Savannah River Site will be used to illustrate key points and lessons learned. It is expected that this information would be useful to other DOE sites, DoD installations and commercial nuclear facilities constructed prior to 1979