Iron and Spinel Precipitation in Iron-Doped Sapphire

Single crystals of Al₂O₃ containing 0.5 wt% Fe were exposed to low p o₂ atmospheres at 1500°C to produce precipitate phases. Analytical TEM identified the precipitate phases as spinel (hercynite) and iron, with the following orientation relationships: 〈001〉_Fe‖〈2 2 01〉_s with {1 1 0}_Fe‖{11 2 0}_s, 〈111〉_Fe‖〈10 1 0〉_s with {0 1 1}_Fe‖ (0001)_s, and 〈1 1 0〉_H‖〈01 1 0〉_s with {111}_H‖ (0001)_s. The three phase fields observed — (Fe, Al)₂O₃, spinel +α-Al₂O₃, and iron +αAl₂O₃— are in accordance with phase stability diagrams. Precipitation kinetics indicate that oxygen is mobile in the reduced region of the crystal.     

Defining Sources of Coffee Plant Odor Attractive toCeratitis Capitata Flies

We evaluated attraction of released mature laboratory-cultured Mediterranean fruit flies to different sources of coffee plant odor placed in potted nonfruiting guava trees in outdoor field cages. Volatiles from crushed medium or dark red fruit ofCoffea arabica cv. arabica plants were significantly more attractive than volatiles from cut leaves or stems of such plants, volatiles from less-ripe crushedC. arabica fruit, and volatiles from crushed red fruit ofC. racemosa,C. canephora, orC. dewevari. Volatiles fromC. arabica cv. arabica crushed red fruit were equally attractive as volatiles from crushed red fruit ofC. congensis orC. arabica cv. mundo, cv. bourbon, cv. kents or cv. catura. Volatiles from as little as 2 g of crushed redC. arabica fruit (= 1 fruit) were as attractive as volatiles from 32 g of such fruit, demonstrating sensitivity of the bioassay approach used to a small amount of source material. Odor ofC. arabica red fruit refrigerated for 1–10 days after picking was significantly more attractive than odor of fresh-picked fruit, while odor of a 24-hr water extract of intact redC. arabica fruit was significantly more attractive than odor of 24-hr extracts of such fruit with methanol, methylene chloride, or hexane or 1- or 6-hr extracts with water. Extraction studies suggested that at least some of the volatiles of red coffee fruit attractive to medflies may be polar water-soluble molecules. In our final test, volatiles from crushed redC. arabica fruit trapped on Super Q and eluted with methylene chloride proved just as attractive as volatiles emanating directly from crushed fruit of the same type. Together, our findings define optimal source material and effective handling procedures of source material for future identification of volatile components of coffee fruit attractive to medflies.     

The effects of chemical structure on the shear rheology of aliphatic polycarbonates

Aliphatic polycarbonates are a relatively new class of polymer, which are characterized by an instability at the functional group, which makes them easily degraded and capable of biodegradation; as such, they constitute a potentially powerful group of polymers for exploitation in green technology. Rheological properties in shear flow are presented for the seven following different aliphatic polycarbonate samples: polyethylene carbonate, polypropylene carbonate, linear pentene polycarbonate, linear hexene polycarbonate, linear octene polycarbonate, cyclohexene polycarbonate, copolymer of propylene oxide (20%), and cyclohexene oxide (80%), using parallel plate rheometry. No studies of the rheological properties of aliphatic polycarbonates have been reported in the literature to date. The steady‐state and the dynamic properties of these new polymers are investigated, and the resulting flow curves and the dynamic relaxation spectra of the aliphatic polycarbonate melts are presented. One of the major problems encountered in trying to characterize the melt rheology and relate behavior to the underlying molecular structure is the instability of the polymers. Because of this, a narrow processing window is present for each polymer, and it makes it impossible to compare all polymers at a constant temperature or range of temperatures in the melt. Nevertheless, some progress can be made. In all cases, the rheological response is discussed in terms of molecular characteristics, in particular, the length of the side chain and the molecular weight distribution. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 93: 534–544, 2004     

One-bath dyeing of polyester/cotton with disperse and bis-3-carboxypyridinium-s-triazine reactive dyes. Part 1: Factors limiting production of heavy shades

Over the last 20 years, selected disperse dyes and bis-3-carboxypyridinium- s -triazine reactive dyes have been widely promoted for the exhaust dyeing of polyester/cotton blends in a one-bath-one-stage ('all-in') process under neutral conditions. However, despite the time and energy savings afforded by this elegant dyeing process, there is a belief in the dyeing industry that economical production is limited to pale and medium depths of shade. In this paper, the two dye classes (disperse dyes on polyester and bis-3-carboxypyridinium- s -triazine reactive dyes on cotton) have been investigated to understand why heavy depths of shade cannot readily be obtained economically using this process.     

Desulphurization of Athabasca petroleum coke by (a) chemical oxidation and (b) solvent extraction

This study concerns the desulphurization of petroleum coke produced by delayed coking of Athabasca bitumen. The coke contains 7.5 wt % sulphur, 99.6% of the sulphur in coke being organic and the remainder pyritic. The coke was treated both with nitric acid and by solvent extraction. During nitric acid treatment, sulphur removal was found to increase with reaction time and the concentration of nitric acid, and to decrease slightly with increase in particle size. About 30% of organic sulphur was removed from ?250 Tyler mesh coke particles by 6 N nitric acid for 4 h at 102 °C. The basic mechanism for this treatment is oxidation and solution of organic sulphur compounds by nitric acid. About 50% ash was also removed from the coke. For solvent extraction, o-chlorophenol was used. Sulphur removal was found to increase with extracting temperature and time, and to decrease with increase in particle size of coke. About 19% of the sulphur was removed from ?250 mesh coke particles by o-chlorophenol at 160 °C in 2 h. When treated consecutively with nitric acid and o-chlorophenol, about 40% of sulphur was removed from the ?250 mesh coke particles.     

Kinetics of the thermo-oxidative and thermal cracking reactions of Athabasca bitumen

The thermo-oxidative and thermal cracking reactions of Athabasca bitumen were examined qualitatively and quantitatively using differential thermal analysis (DTA). Reaction kinetics of low temperature oxidation (LTO) and high temperature cracking (HTC) were determined. The rate of the LTO reaction was found to be first order with respect to oxygen concentration. The activation energy and the Arrhenius pre-exponential factor were 64 MJ kg^?1 mol^?1 and 10^5.4 s^?1, respectively. The effects of atmosphere, pressure, heating rate and support material on the thermal reactions of bitumen were studied. In general, it was found that partial pressures of oxygen > 10% O₂ favoured exothermic oxidation reactions. High pressure increased the rates of LTO and HTC as well as the exothermicity of these reactions. A major contribution of this study to thermal in-situ processes is that heating rate can be used effectively to control the extent of low temperature oxidation and hence fuel availability during in-situ combustion. Low linear heating rates (2.8 °C min^?1) favoured low temperature oxidative addition and fission reactions. The reaction products readily formed coke and combusted upon heating. High linear heating rates (24.5 °C min ^?1) led to rapid oxidation reactions in the high temperature zone; the high temperature and the energy released during oxidation appeared to promote combustion. Finally, when sand was used as the support material there appeared to be a catalytic effect in both LTO and HTC reactions.     

Functionalisation of lyocell. Part 1: Amination of lyocell with m-phenylenediaminesulphonic acid derivatives

A series of four colourless, water-soluble agents, based on m -phenylenediaminesulphonic acid, and designed to aminate lyocell, have been synthesised. Each agent carried one or two aromatic amino groups ortho to a water solubilising sulphonic acid group, together with one or two electrophilic groups. The electrophilic groups studied were dichlorotriazinyl, monochlorotriazinyl, vinylsulphonyl and triazinyl betaine. The agents were applied to lyocell by padding techniques, and neutral-exhaustion dyeing of the aminated fibres, with low, medium and high reactivity reactive dyes, in the presence of salt, were performed. Only the high reactivity dichlorotriazinyl dye gave encouraging results. The aminated fabrics, containing aromatic amino groups with an o -sulphonic acid, were insufficiently nucleophilic to allow significant covalent bonding with the low/medium reactivity dyes at both 60 and 80 °C.     

Underpaint corrosion of zinc-coated steel sheet studied by in situ raman spectroscopy

The corrosion of zinc-coated steel sheets was studied by Raman spectroscopy. In aerated 0.03 M NaCl solutions, a large variety of corrosion products were identified in situ on unpainted sheets after 7 days of immersion. Zinc oxide, zinc hydroxychloride and zinc hydroxide were observed. For painted specimens, two main products, zinc oxide and zinc hydroxychloride, have been identified under paint blisters. It appeared that a different type of corrosion process is occurring under a paint film. It is hypothesized that the barrier properties of the paint are capable of modifying the mechanisms and thus the nature of the corrosion products. However, for both unpainted and painted specimens the nature of the corrosion products seems to depend on the local pH values in relation to chloride concentrations.