Fluid Mechanics of Biological Surfaces and their Technological Application

 A survey is given on fluid-dynamic effects caused by the structure and properties of biological surfaces. It is demonstrated that the results of investigations aiming at technological applications can also provide insights into biophysical phenomena. Techniques are described both for reducing wall shear stresses and for controlling boundary-layer separation. (a) Wall shear stress reduction was investigated experimentally for various riblet surfaces including a shark skin replica. The latter consists of 800 plastic model scales with compliant anchoring. Hairy surfaces are also considered, and surfaces in which the no-slip condition is modified. Self-cleaning surfaces such as that of lotus leaves represent an interesting option to avoid fluid-dynamic deterioration by the agglomeration of dirt. An example of technological implementation is discussed for riblets in long-range commercial aircraft. (b) Separation control is also an important issue in biology. After a few brief comments on vortex generators, the mechanism of separation control by bird feathers is described in detail. Self-activated movable flaps (=artificial bird feathers) represent a high-lift system enhancing the maximum lift of airfoils by about 20%. This is achieved without perceivable deleterious effects under cruise conditions. Finally, flight experiments on an aircraft with laminar wing and movable flaps are presented.     

Sulfate as tridentate ligand

Dedicated to Professor H. J. Berthold, Hannover, on the occasion of his 65th birthday.     

Emerging technologies for in-situ groundwater remediation

There are numerous technologies currently being tested by EPA, universities throughout the world, and private research organizations. A few of the more promising innovative technologies as well as fully tested and proven remedies for treating contaminated groundwater are presented in this article. Although several of those technologies have been in existence for only four to five years, the results of full-scale testing are being produced. The method for each of these promising technologies is described, results from recent field-scale studies are summarized, and a discussion of cost is presented.     

Lessons after Bhopal: CSB a catalyst for change

The Bhopal tragedy was a defining moment in the history of the chemical industry. On December 3, 1984, a runaway reaction within a methyl isocyanate storage tank at the Union Carbide India Limited pesticide plant released a toxic gas cloud that killed thousands and injured hundreds of thousands. After Bhopal, industrial chemical plants became a major public concern. Both the public and the chemical industry realized the necessity of improving chemical process safety.

Bhopal served as a wake-up call. To prevent the same event from occurring in the United States, many legislative and industrial changes were invoked—one of which was formation of the U.S. Chemical Safety and Hazard Investigation Board (CSB). The ultimate goal of CSB is to use the lessons learned and recommendations from its investigations to achieve positive change within the chemical industry—preventing incidents and saving lives.

Although it seems clear that the lessons learned at Bhopal have improved chemical plant safety, CSB investigations indicate that the systemic problems identified at Bhopal remain the underlying causes of many incidents. These include:

• Lack of awareness of reactive hazards.

• Lack of management of change.

• Inadequate plant design and maintenance.

• Ineffective employee training.

• Ineffective emergency preparedness and community notification.

• Lack of root cause incident investigations and communication of lessons learned.

The aim of this paper is to present common themes from recent cases investigated by CSB and to discuss how these issues might be best addressed in the future.

This paper has not been independently approved by the Board and is published for general informational purposes only. Any material in the paper that did not originate in a Board-approved report is solely the responsibility of the authors and does not represent an official finding, conclusion, or position of the Board.     

Power matters in closing the phenotyping gap

Much of our understanding of physiology and metabolism is derived from investigating mouse mutants and transgenic mice, and open-access platforms for standardized mouse phenotyping such as the German Mouse Clinic (GMC) are currently viewed as one powerful tool for identifying novel gene-function relationships. Phenotyping or phenotypic screening involves the comparison of wild-type control mice with their mutant or transgenic littermates. In our study, we explored the extent to which standardized phenotyping will succeed in detecting biologically relevant phenotypic differences in mice generated and provided by different collaborators. We analyzed quantitative metabolic data (body mass, energy intake, and energy metabolized) collected at the GMC under the current workflow, and used them for statistical power considerations. Our results demonstrate that there is substantial variability in these parameters among lines of wild-type C57BL/6 (B6) mice from different sources. Given this variable background noise in mice that serve as controls, subtle phenotypes in mutant or transgenic littermates may be overlooked. Furthermore, a phenotype observed in one cohort of a mutant line may not be reproducible (to the same extent) in mice coming from a different environment or supplier. In the light of these constraints, we encourage researchers to incorporate information on intrastrain variability into future study planning, or to perform advanced hierarchical analyses. Both will ultimately improve the detectability of novel phenotypes by phenotypic screening. Carola W. Meyer and Ralf Elvert contributed equally to this work.     

Secondary analysis of time of day on simulated driving performance

PROBLEM: Age and gender are frequently controlled for in studies of driving performance, but the effects of time of day or circadian cycles on performance are often not considered. Previous research on time of day effects of simulated driving is contradictory and provides little guidance for understanding the impact of these variables on results. METHODS: Using driving simulator data from 79 subjects ages 18 to 65, this paper focuses on the impact of age, gender, and time of day on the simulated driving performance of subjects who self-selected the time of participation. RESULTS: Time of day effects were consistently evident for drivers' speed overall and across different simulated environments. Drivers in the late afternoon period consistently drove significantly slower than drivers in other time periods. Age and gender affected speed such that women and those participants 50 and older tended to drive more slowly. Time of day also had an effect on reaction time and on speed variability measures. Gender did not have significant effects on reaction time or variability measures, but age effects were present. SUMMARY: Taken together, the results suggest that time of day effects should be considered as part of simulated driving performance, and that interactions between time of day and other variables, notably age, should be controlled for as part of future research. IMPACT ON INDUSTRY: Implications of these findings on current efforts for older driver testing are discussed.