The European Joint Aviation Authorities: Meeting the Challenges of International Cooperation

Even before the Treaty of Maastricht was signed in 1992, European leaders were looking toward a union of nation-states held together not by force but by a common goal to promote European trade, culture, economics, and technology. It is unlikely, however, that history will recount the unification of Europe as a grand and romantic revolutionary development. It has been, and continues to be, a gradual and evolutionary integration full of criticism and ethnic-based conflicts. Many questions still must be answered. The need to strike a balance between centralization and decentralization is pressing and difficult to meet

Training Pilots or Educating Captains? A Framework for Collegiate Ab Initio Programs

During the past five years, several studies have been conducted to assess the future availability of airline pilots and other aviation professionals (McDonnell Douglas Aircraft Co., 1989; Sypher-Mueller International, 1992; U.S. Department of Defense, 1988; U.S. Department of Transportation, Federal Aviation Administration [FAA], 1993). These studies conclude, not surprisingly, that the traditional sources of airline pilots-the military and general aviation-are in a period of decline. This situation, coupled with the predicted flood of airline pilot retirements, will lead to a shortage of pilots before the end of the decade. Although estimates vary, most suggest that the current excess of pilots will be absorbed by 1996

Association of Type 1 Diabetes vs Type 2 Diabetes Diagnosed During Childhood and Adolescence With Complications During Teenage Years and Young Adulthood

The burden and determinants of complications and comorbidities in contemporary youth-onset diabetes are unknown

Digital In-Line Holography as a Three-Dimensional Tool to Study Motile Marine Organisms During Their Exploration of Surfaces

The swimming patterns of zoospores of the green alga Ulva linza in the vicinity of a surface were investigated by digital in-line holography. Full 3D motion patterns were retrieved from measurements and the traces obtained were compared with known swimming patterns of spores of the brown alga Hincksia irregularis and the green alga Ulva linza as seen in a conventional optical microscope. Quantitative information such as swimming velocity was calculated from the 3D traces. The results demonstrate the potential of digital in-line holography to image and quantify exploratory patterns of behavior of motile spores close to surfaces. This technique can give detailed insight into mechanisms of surface colonization by spores and larvae of fouling organisms in response to changes in surface properties

Marine Fouling Release Silicone/Carbon Nanotube Nanocomposite Coatings: On the Importance of the Nanotube Dispersion State

The present work reports on the influence of the dispersion quality of multiwall carbon nanotubes (MWCNTs) in a silicone matrix on the marine fouling-release performance of the resulting nanocomposite coatings. A first set of coatings filled with different nanofiller contents was prepared by the dilution of a silicone/MWCNTs masterbatch within a hydrosilylation-curing polydimethylsiloxane resin. The fouling-release properties of the nanocomposite coatings were studied through laboratory assays with the marine alga (seaweed) Ova, a common fouling species. As reported previously (see Ref. [19]), the addition of a small (0.05%) amount of carbon nanotubes substantially improves the fouling-release properties of the silicone matrix. This paper shows that this improvement is dependent on the amount of filler, with a maximum obtained with 0.1 wt% of multiwall carbon nanotubes (MWCNTs). The method of dispersion of carbon nanotubes in the silicone matrix is also shown to significantly (p = 0.05) influence the fouling-release properties of the coatings. Dispersing 0.1% MWCNTs using the masterbatch approach yielded coatings with circa 40% improved fouling-release properties over those where MWCNTs were dispersed directly in the polymeric matrix. This improvement is directly related to the state of nanofiller dispersion within the cross-linked silicone coating

Physicochemical Properties of (Ethylene Glycol)-Containing Self-Assembled Monolayers Relevant for Protein and Algal Cell Resistance

The influence of the number of repeating units in self-assembled monolayers (SAMs) of ethylene glycol and of their end-group termination on the settlement and adhesion of two types of algal cells, viz., zoospores of the macroalga Ulva and cells of the diatom Navicula, was studied. The findings are related to the resistance of these surfaces against fibrinogen adsorption. Results showed that settlement and adhesion of algal cells to oligo(ethylene glycol) (OEG; 2−6 EG units) and poly(ethylene glycol) (PEG; MW = 2000, 5000) SAMs was low, while resistance was less effective for mono(ethylene glycol) (EG1OH)-terminated surfaces. These findings concur with former protein adsorption studies.(1, 2) In situ microscopy showed that PEG surfaces inhibited the settlement of zoospores, i.e., zoospores did not attach to the surfaces and remained motile. In contrast, on EG2−6OH surfaces, although zoospores settled, i.e., they secreted adhesive and lost motility, adhesion between secreted adhesive and the surface was extremely weak, and the settled spores were unable to bond to the surfaces. The influence of surface properties such as hydration, conformational degrees of freedom, and interfacial characteristics of the SAMs is discussed to understand the underlying repulsive mechanisms occurring in (ethylene glycol)-based coatings

Nanostructured Films of Amphiphilic Fluorinated Block Copolymers for Fouling Release Application

New amphiphilic block copolymers SnSzm consisting of blocks with varied degrees of polymerization, n and m, of polystyrene, S, and polystyrene carrying an amphiphilic polyoxyethylene–polytetrafluoroethylene chain side-group, Sz, were prepared by controlled atom transfer radical polymerization (ATRP). The block copolymers, either alone or in a blend with commercial SEBS (10 wt% SEBS), were spin-coated in thinner films (200–400 nm) on glass and spray-coated in thicker films (~ 500 nm) on a SEBS underlayer (150–200 μm). Angle-resolved X-ray photoelectron spectroscopy (XPS) measurements proved that at any photoemission angle, φ, the atomic ratio F/C was larger than that expected from the known stoichiometry. Consistent with the enrichment of the outer film surface (3–10 nm) in F content, the measured contact angles, θ, with water (θw ≥ 107°) and n-hexadecane (θh ≥ 64°) pointed to the simultaneous hydrophobic and lipophobic character of the films. The film surface tension γS calculated from the θ values was in the range of 13–15 mN/m. However, the XPS measurements on the ‘wet’ films after immersion in water demonstrated that the film surface underwent reconstruction owing to its amphiphilic nature, thereby giving rise to a more chemically heterogeneous structure. The atomic force microscopy (AFM) images (tapping mode/AC mode) revealed well defined morphological features of the nanostructured films. Depending on the chemical composition of the block copolymers, spherical (ca. 20 nm diameter) and lying cylindrical (24–29 nm periodicity) nanodomains of the S discrete phase were segregated from the Sz continuous matrix (root mean square, RMS, roughness ≈ 1 nm). After immersion in water, the underwater AFM patterns evidenced a transformation to a mixed surface structure, in which the nanoscale heterogeneity and topography (RMS = 1–6 nm) were increased. The coatings were subjected to laboratory bioassays to explore their intrinsic ability to resist the settlement and reduce the adhesion strength of two marine algae viz. the macroalga (seaweed) Ulva linza, and the unicellular diatom Navicula perminuta. The amphiphilic nature of the copolymer coatings resulted in distinctly different performances against these two organisms. Ulva adhered less strongly to the coatings richer in the amphiphilic polystyrene component, percentage removal being maximal at intermediate weight contents. In contrast, Navicula cells adhered less strongly to coatings with a lower weight percentage of the amphiphilic side chains. The results are discussed in terms of the changes in surface structure caused by immersion and the effects such changes may have on the adhesion of the test organisms