91 |
The advantage of juvenile coloration in reef fishesMahon, Jeffrey L 12 1900 (has links)
Juvenile reef fishes often have a color pattern different from that of adults. It
has been theorized that this reduces the aggression received by juveniles from adult
conspecifics. This was tested using two species of Labroides cleaning wrasses in which
certain-sized individuals can quickly shift back and forth between the adult and juvenile
color patterns. Adult Labroides phthirophagus has the same single-male grouping
social structure as previously described for L. dimidiatus. Small L. phthirophagus and
L. dimidiatus in juvenile coloration shifted to adult coloration when isolated and then
quickly shifted back to juvenile coloration when chased by an adult conspecific female.
In L. phthirophagus the adult females attacked small cleaners more frequently when
they displayed the adult color pattern, indicating that juvenile coloration gives some
protection from conspecific aggression. Two other species oflabrids, Thalassoma
duperrey and Coris gaimard, showed the ability to shift back to juvenile coloration
when aggression was received from con specific adults, although the shift was not nearly
as rapid as seen in Labroides species.
Dascyllus albisella and Zebrasomajlavescens, common reef fishes, preferred to
solicit cleaning (by posing) from the adult-colored L. phthirophagus, indicating that
some hosts prefer the adult color pattern. Small L. phthirophagus shifted to adult
coloration more quickly when starved than when provided with host fish on which to
feed, indicating that the coloration shift is motivated by hunger. Even though juvenile coloration in some fishes may reduce the aggression
received from adults, in cleaner wrasses it also reduces food availability, making it
advantageous for them to shift to adult-coloration as soon as possible. Cleaner wrasses
have developed a quick, reversible coloration shift that allows changing to adult
coloration at a small size but allows reversing coloration if too much aggression is
received. / x, 59 leaves, bound : ill., maps ; 29 cm.
|
92 |
Towards the synthesis of new barrier coatings for cork /Ma, Rosalind. Unknown Date (has links)
Cork has traditionally been the preferred closure for wines. This is attributed to its unique physical properties, which include long lasting flexibility, hydrophobicity, and depending on the quality of the cork, low permeability. However, after bottling, taint compounds originating from the cork, migrate into the wine and cause an “off-musty” odour or taste, which is undesirable. The known taint compounds are geosmin; isoborneol; 1-octen-3-one; 1-octen-3-ol; tetrachloroanisole and finally trichloroanisole, which has been found to be the major cause. Only 7% of all cork-stoppered wines are affected by cork taint. Worldwide, it is estimated that $1 billion per year is lost due to contamination by taint compounds; this does not include other types of food and beverages. Current methods of processing and treating corks have failed to eliminate cork taint entirely. / Thesis (PhDAppliedScience)--University of South Australia, 2002.
|
93 |
Mechanisms of protective FeCO₃ film removal in single-phase flow-accelerated CO₂ corrosion of mild steel.Ruzic, Vukan Unknown Date (has links)
Carbon dioxide (CO2) corrosion is a major problem in the oil and gas production industry. The survival of mild steel equipment is to a large extent conditional on the formation and stamina of protective iron carbonate (FeCO3) films. Damage to protective films allegedly leads to accelerated corrosion attacks and increases the risk of failures. In single-phase flows, film removal phenomena are broadly ascribed to two intrinsic mechanisms: mechanical removal by hydrodynamic forces and/or chemical removal by dissolution. The fact that both mechanisms usually act simultaneously in practice puts their combined action in the forefront regarding its significance and relevance for the industry. Yet, virtually no information is available on the exact conjoint mechanism of protective FeCO3 film removal in single-phase environments. The obscurity is largely due to the uncertainty regarding the roles of hydrodynamic forces and mass transfer, where both are closely related to turbulence intensity levels. The aim of this dissertation was to clarify the roles of the two basic FeCO3 film removal mechanisms during the conjoint removal in undisturbed, single-phase flow in terms of their relative contribution and possible synergistic interaction. The proposed aim was accomplished by applying an innovative analytical approach, in which inherently coupled processes of film formation and removal were decoupled. Also, the two intrinsic removal mechanisms were studied separately in the initial stages, before they were combined to provide a complete picture of the conjoint mechanism. An integrated approach to studying film formation/removal mechanisms involved advanced electrochemical techniques for following film growth/removal, complemented by detailedScanning Electron Microscopy/Energy Dispersive Spectroscopy/X-Ray Mapping characterisations of protective/residual films. A single-phase, highly turbulent flow field was attained by employing a rotating cylinder configuration. A standard corrosion experimental setup was extended to accommodate more complex film studies. A comprehensive flow characterisation around the rotating cylinder was carried out by means of flow visualisation and mass transfer measurements under turbulent flow conditions. While the former facilitated proper design of film formation experiments, the latter led to an empirical mass transfer correlation that enabled quantification of film dissolution rates. Furthermore, although some information on film growth kinetics is available, customised experimentation was necessary to identify the key parameters needed to obtain films with desired characteristics. Sound procedures for FeCO3 film growth were established, which led to the reproducible formation of realistic, protective films after a few days. The results of the pure mechanical removal of protective FeCO3 films have shown that its kinetics are rather slow even at high velocities and have caused a delayed, partial macroscopic type of damage. Yet, the findings demonstrate that the currently widely accepted view, that film removal by hydrodynamic forces in the absence of film dissolution in undisturbed, single-phase flows does not occur, is wrong. The strong correlation found between velocity and pure chemical film removal kinetics implicitly followed via corrosion rates suggests that the dissolution of protective FeCO3 films is under mass transfer control. Pure dissolution has faster removal kinetics and is far more detrimental to film integrity even at relatively high pH (just below saturation) than pure mechanical removal at the same Reynolds number. It has been found that the controlled pure dissolution mechanism led to only partial and selective film removal, where the more dissolution-resistant crystalline top film layer and the dissolution-prone inner layer were differently affected both in terms of the type of damage and its severity. A strong synergistic effect between mechanical and chemical film removal mechanisms has been identified during their simultaneous action. The quantified synergistic share in fully established conjoint film removal (during the steady, linear corrosion rate increase) expressed via corrosion rate gradients increased from 19.4% to 29.7% for the corresponding increase in the rotational speed from 7,000 rpm to 10,000 rpm. The synergism comprised two modes of mutual interactions: enhanced mechanical removal due to dissolution (M/D) and enhanced dissolution due to mechanical removal (D/M). In contrast to the independent action of integral removal mechanisms, where dissolution appears to be more destructive, the interaction between the two was primarily dominated by drastically accelerated mechanical film removal kinetics, that is, M/D rather than D/M mode, the latter of which was inferior. A fundamentally improved understanding of film removal mechanisms in single-phase flows has been reached as a result of the present project, thereby creating a solid foundation for future modelling and a more effective prevention and control of flow accelerated corrosion, not only in CO2 corrosive environments, but also in a wide range of industrial settings.
|
94 |
Short-circuit current calculations and protective relay coordination for industrial and commercial power systemsMohammadi, Houshang C. January 1986 (has links)
Thesis (M.S.)--Ohio University, August, 1986. / Title from PDF t.p.
|
95 |
Footwear for cold environments : thermal properties, performance and testing /Kuklane, Kalev. January 1900 (has links)
Diss. (sammanfattning) Luleå : Univ., 2000. / Härtill 10 uppsatser.
|
96 |
Microwave enhanced chemical vapor deposition of silicon compound thin films and their characterizationGopal, Madan. January 1991 (has links)
Thesis (M.S.)--Ohio University, November, 1991. / Title from PDF t.p.
|
97 |
Remote microwave-enhanced chemical vapor deposition of silicon-nitrogen (SixNy) thin filmsGladysz, Gary M. January 1991 (has links)
Thesis (M.S.)--Ohio University, August, 1991. / Title from PDF t.p.
|
98 |
A study of impact using 80-derometer rubberHoward, Steven H. January 1998 (has links)
Thesis (M.S.)--West Virginia University, 1998. / Title from document title page. Document formatted into pages; contains ix, 127 p. : ill. (some col.). Includes abstract. Includes bibliographical references (p. 91-92).
|
99 |
Corrosion performance of epoxy-coated reinforcement in aggressive environments /Vaca-Cortés, Enrique, January 1998 (has links)
Thesis (Ph. D.)--University of Texas at Austin, 1998. / Vita. Includes bibliographical references (leaves 797-811). Available also in a digital version from Dissertation Abstracts.
|
100 |
Synthesis of maleated poly(vinylidene fluoride) in supercritical carbon dioxide mediumClark, Kelly L., January 2004 (has links)
Thesis (Ph. D.)--University of Missouri-Columbia, 2004. / Typescript. Vita. Includes bibliographical references (leaves 75-82). Also available on the Internet.
|
Page generated in 0.0424 seconds