Mirror Constant for Tyranno® Silicon-Titanium-Carbon-Oxygen Fibers Measured in Situ in a Three-Dimensional Woven Silicon Carbide/Silicon Carbide Composite

The strength, S , of ceramic and glass fibers often can be estimated from fractographic investigation using the fracture mirror radius, r _m, and the relationship S = A _m/( r _m)^1/2, where A _mis the "mirror constant." The present work estimates the value of A _mfor Tyranno^® Si-Ti-C-O fibers in situ in a three-dimensional woven SiC/SiC-based composite to be 2.50 ± 0.09 MPa·m^1/2. This value is within the range of 2–2.51 MPa·m^1/2 previously obtained for nominally similar Nicalon^® Si-C-O fibers.     

Role of semiochemicals in mate location by parasitic sea louse,Lepeophtheirus salmonis

The role of olfaction and diffusible pheromones in mate location behavior of sea lice, Lepeophtheirus salmonis, was assessed with Y-tube behavioral bioassays. The pheromone emitting animals were located in a chamber in one arm of a Y-tube arena, with artificial seawater flowing through both arms. Adult male sea lice displayed both activation and directional responses to seawater conditioned with preadult II virgin females, but were only activated by mated adult female conditioned water. Further, when males were given the choice of preadult II virgin females or mated adult females, a significant number of males chose the arm with the preadult II virgin females. Adult males showed activation responses when presented with water conditioned with adult males but were not attracted to them. When presented with adult males, preadult II virgin females showed only directional responses, but not activation responses. Preadult II virgin female conditioned water was extracted using solid-phase extraction (SPE) protocols pioneered for semiochemical isolation. Adult male sea lice showed significant directional responses to the preadult II virgin female SPE extract. Distillation under vacuum was performed on the extract to give a distillate comprising components with a molecular weight range and physical properties comparable to those of compounds utilized as volatile semiochemicals by terrestrial organisms and a residue comprising components with higher molecular weight range comparable to those utilized as involatile semiochemicals. Adult males were found to be both significantly activated and attracted to the distillate, but not to the residue. This research provides evidence that small, lipophilic organic molecules are used by sea lice as sex pheromone signals to locate a member of the opposite sex.     

Bioremediation of polycyclic aromatic hydrocarbons: current knowledge and future directions

Polycyclic aromatic hydrocarbons (PAHs) are a class of organic compounds that have accumulated in the natural environment mainly as a result of anthropogenic activities such as the combustion of fossil fuels. Interest has surrounded the occurrence and distribution of PAHs for many decades due to their potentially harmful effects to human health. This concern has prompted researchers to address ways to detoxify/remove these organic compounds from the natural environment. Bioremediation is one approach that has been used to remediate contaminated land and waters, and promotes the natural attenuation of the contaminants using the in situ microbial community of the site. This review discusses the variety of fungi and bacteria that are capable of these transformations, describes the major aerobic and anaerobic breakdown pathways, and highlights some of the bioremediation technologies that are currently available. Copyright © 2005 Society of Chemical Industry     

<Emphasis Type="Italic">In situ</Emphasis> monitoring of solid fat content by means of pulsed nuclear magnetic resonance spectrometry and ultrasonics

An ultrasonic technique was developed to study the crystallization process of edible fats on-line. A chirp wave was used instead of the conventional pulser signal, thus achieving a higher signal-to-noise ratio. This enabled measurements to be made in concentrated systems [≈20% solid fat content (SFC)] through a 8.11-cm thick sample without significant signal loss. Fat samples were crystallized at 20, 25, and 30°C at a constant agitation rate of 400 rpm for 90 min. The crystallization process was followed by ultrasonic spectroscopy and a low-resolution pulsed nuclear magnetic resonance spectrometer. Specific relationships were found between ultrasonic parameters [integrated response, time of flight (TF), and full width half maximum] and SFC. TF, which is an indirect measurement of the ultrasonic velocity (v), was highly correlated to SFC (r ²>0.9) in a linear fashion (v=2.601 SFC+1433.0).     

The Instabilisation of Dye-Fibre Bonds by Peroxide Treatments

The results are presented of an investigation into the instability induced in dye-fibre bonds by peroxide treatments. The nature of the reactions involved are discussed.     

The mechanism of photoprotection of wool by UV absorbers of the 2-hydroxybenzophenone class

The mechanism by which sulfonated 2-hydroxybenzophenone ultraviolet (UV) absorbers protect wool fabric against photoyellowing has been studied. The absorption and luminescence properties of two 2-hydroxybenzophenone-5-sulfonates and four 2-hydroxybenzophenone-2′hyphen;sulfonates are compared. The 2-hydroxy-benzophenones are nonfluorescent in wool, but they all show phosphorescence at room temperature. The phosphorescence is attributed to the phenolate anion produced by ionization of the hydroxyl group. The nature of substituents in the 3-position and 4-position of the phenolic ring is important in controlling the formation of luminescent species which may initiate unwanted photochemical reactions in wool. The protective screening effect of each absorber in wool fabric has been determined theoretically, using a method of analysis based on diffuse reflectance spectroscopy; the results are compared with the values determined experimentally by measuring the changes in yellowness that result when treated and untreated fabrics are exposed to fluorescent sunlamps (maximum energy at 310 nm). In all cases, UV screening was shown to be the important mode of photostabilization. The levels of photoprotection were much higher than those reported previously for treated fabrics that were exposed for long periods to simulated sunlight, behind glass. Possible reasons for the poor long-term performance of the 2-hydroxybenzophenones in wool are discussed.     

Relative roles of chemical and mass transfer rate control in fluidized-bed combustion of coal chars

The relative roles of mass transfer and chemical reaction in controlling combustion rates in fluidized beds are examined in the light of measurements of char-particle combustion kinetics and correlated data on gas—particle mass transfer in fluidized beds. It is concluded that at 1200 K mass transfer is the main rate-control influence for materials having reactivities the same as, or higher than, a char from a swelling bituminous coal. Mass transfer has little effect on the combustion rate of materials whose reactivity to oxygen is one-tenth that of the bituminous coal char. At 800 K, chemical reaction control is dominant for all reactivities considered. The main uncertainty in the present calculations arises from the lack of a suitable analysis of mass-transfer rates in conditions appropriate to fluidized-bed combustion.     

Comments on the use of buckminsterfullerene encapsulated in zeolite Y as a potential catalyst

Buckminsterfullerene encapsulated within zeolite Y is found not to be a reactive radical initiator for the formation of dimethoxyethane from dimethyl ether below 200° C. Above this temperature the expected acid catalysed conversion of dimethyl ether to hydrocarbons is observed. Dimethoxyethane formation is observed when bibenzoyl peroxide is used as a radical initiator. These studies indicate that any radical formed by the encapsulated buckminsterfullerene is relatively unreactive.     

Azide Reactive Dyes

Reactive dyes containing a sulphonylazide group can undergo fixation on nylon substrates by two different mechanisms. Under aqueous dyeing conditions, at or below 120d? C, the free amino end-groups of the polymer attack the sulphonylazide group with displacement of azide ion, and results in attachment of the dye to the substrate by a sulphonamide linkage. In contrast, if the dyed substrate is subjected to dry heat fixation at 170d? C, the azide group decomposes to a sulphonylnitrene species which undergoes insertion into C-H bonds of the polymer. The dye is again attached by a sulphonamide bridge, but in this case the amount of dye that can be fixed is independent of the amino end-group content of the polymer.