Secretion and secretory tissues of the anal sac of the mink,Mustela vison

The sulfur-rich anal sac secretion of the mink,Mustela vison, consisted of immiscible lipid (1.7% sulfur) and aqueous (0.7% sulfur) phases. Light and electron microscopy revealed secretory tissue of two types, sebaceous (holocrine) and apocrine. A major input of sulfur into the sac appeared to be associated with glycoprotein granules present in the apical portions of the apocrine cells as X-ray energy probe microanalysis showed these to contain relatively high levels of sulfur. The lipid of the secretion, presumed to be largely of sebaceous origin, consisted mainly of wax monoesters, while the aqueous phase contained volatile fatty acids, ammonia, and amines, including putrescine (1,4-diaminobutane). The identity of the major headspace volatiles was confirmed by NMR, MS, and Raney nickel desulfuration as being 2,2-dimethylthiacyclobutane and 3,3-dimethyl-1, 2-dithiacyclopentane. These compounds were not detected by GC-MS in the headspace volatiles of the anal sac secretions of eight other mustelid species examined. Other sulfur compounds detected included isomeric dimethylthiacyclobutanes, a number of disulfides and 3-methyl-but-3-enyl methyl sulfide (isopentenyl methyl sulfide). The significance of these findings is discussed.     

Investigations of Electrical Properties in Silica/Indium Tin Oxide Two-Layer Film for Effective Electromagnetic Shielding

The effect of zinc ions added to silica film on the electrical and structural properties of a silica/indium tin oxide two-layer film which had been prepared by solution coating for electromagnetic shielding of displays was studied. The volume resistivity of the undoped silica/indium tin oxide film was more than 3 times as high as that of the zinc-doped silica/indium tin oxide film. The addition of divalent cations, zinc ions, to the overcoated layer led volume resistivity of the two-layer film to decrease significantly and also caused a long-term increase in stability. The decrease in volume resistivity was due to the addition of zinc ions that changed the interface ionization and helped to enhance the electrical conductivity in the two-layer film.     

Preliminary evaluation of the anticorrosive properties of aircraft coatings by electrochemical methods

Strict regulations concerning the content of volatile organic compounds (VOCs) and heavy metals (Cr⁶⁺) in aircraft coating systems have increased the economic burden of the United States Air Force (USAF) in the area of coating maintenance. To this end, it is critical to have methods to characterize new coating systems in such a manner that the data can be used to predict accurately and reliably the expected lifetime of the coatings in service. Electrochemical noise method (ENM) and electrochemical impedance spectroscopy (EIS) are two techniques used to monitor extent and rate of corrosion. The USAF is currently employing these methods in order to supplement data acquired from traditional salt-spray methods. ENM and EIS are used to evaluate each component of the coating system and its contribution to corrosion prevention. Preliminary evaluations of an aircraft coating system on aluminum substrate (Al 2024-T3) produces resistance noise values of 10⁶ to 10⁷ Ω/cm². It is hoped that these results will form the basis of coatings that give increased USAF fleet service life and reduction in maintenance manpower and materials costs.     

Complete Oxidation of Methane at Low Temperature over Pt Catalysts Supported on High Surface Area SnO2

The catalytic activity of Pt catalysts supported on high surface area tin(IV) oxide in the complete oxidation of CH₄ traces under lean conditions at low temperature was studied in the absence and in the presence of water (10 vol.%) or H₂S (100 vol.ppm). Their catalytic properties were compared to those of Pd/Al₂O₃ and Pt/Al₂O₃. In the absence of H₂S in the feed, Pt/SnO₂appears as a very promising catalyst for CH₄ oxidation, being even significantly more active under wet conditions than the best reference catalyst, Pd/Al₂O₃. Catalysts steamed-aged at 873 K were also studied in order to simulate long term ageing in real lean-burn NGV exhaust conditions. To this respect, Pt/SnO₂ is slightly less resistant than Pd/Al₂O₃. In the presence of H₂S, Pt/SnO₂catalysts are rapidly and almost completely poisoned, comparably to Pd/Al₂O₃and the catalytic activity is hardly restored upon oxidising treatment below 773 K. A synergetic effect between Pt and specific surface SnO₂sites active in CH₄oxidation is proposed to explain the superior catalytic behaviour of Pt/SnO₂.     

Frying quality and stability of low-and ultra-low-linolenic acid soybean oils

To determine effects of very low levels of linolenic acid on frying stabilities of soybean oils, tests were conducted with 2% (low) linolenic acid soybean oil (LLSBO) and 0.8% (ultra-low) linolenic acid soybean oil (ULLSBO) in comparison with cottonseed oil (CSO). Potato chips were fried in the oils for a total of 25 h of oil use. No significant differences were found for either total polar compounds or FFA between samples of LLSBO and ULLSBO; however, CSO had significantly higher percentage of polar compounds and FFA than the soybean oils at all sampling times. Flavor evaluations of fresh and aged (1, 3, 5, and 7 wk at 25°C) potato chips showed some differences between potato chips fried in different oil types. Sensory panel judges reported that potato chips fried in ULLSBO and aged for 3 or 7 wk at 25°C had significantly lower intensities of fishy flavor than did potato chips fried in LLSBO with the same conditions. Potato chips fried in ULLSBO that had been used for 5 h and then aged 7 wk at 25°C had significantly better quality than did potato chips fried 5 h in LLSBO and aged under the same conditions. Hexanal was significantly higher in the 5-h LLSBO sample than in potato chips fried 5 h in ULLSBO. The decrease in linolenic acid from 2 to 0.8% in the oils improved flavor quality and oxidative stability of some of the potato chip samples.     

Sodium Coordination Environments in Silica Films

The local structure centered on sodium after diffusion in silica (Na-SiO₂ samples) has been determined by means of extended X-ray absorption fine structure (EXAFS) studies. The Na-SiO₂ samples are of particular interest because (i) their sodium content can be varied over a wide range of concentration and (ii) their local structure is representative of that of soda–silica glass. EXAFS analyses reveal the existence of a well-defined local structure involving oxygen, sodium, and silicon neighbors. The Na-O, Na-Na, and Na-Si bonds lengths, which amount to 0.23, 0.30, and 0.38 nm, respectively, do not depend on sodium concentration. This environment closely resembles that found in soda–silica glass. Moreover, it is compatible with the "target site" and "the site memory effect" suggested by recent theories of the ionic conductivity in oxide glasses.     

Effect of thiophosphoryl compounds as accelerators and coupling agents on the vulcanization of NR‐XNBR blend

The effect of a number of thiophosphoryl compounds [viz., bis(isobutyl) thiophosphoryl di‐, tri‐, and tetrasulfides and bis(dicyclohexyl) thiophopsphoryl di‐, tri‐, and tetrasulfides] on natural rubber (NR)‐carboxylated nitrile rubber (XNBR) blend was studied. All these thiophosphoryl compounds are capable of forming interrubber links leading to covulcanized blends which exhibit a fair degree of synergism with respect to physical properties, the maximum being obtained at the 25% NR and 75% XNBR blend composition. This is an obvious claim that the blend under investigation is technologically compatible, having some degree of interrubber interaction which is enhanced in case of two‐stage vulcanization. The existence of interrubber interaction is judged by the swelling experiment. The blend morphology assessed by SEM micrographs corroborates the foregoing observations and accounts for the significant improvement in physical properties of the blend vulcanizates, particularly in two‐stage vulcanization. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 86: 3286‐3299, 2002     

不饱和聚酯片状模塑料力学性能的研究

研究了玻纤布、短切玻纤及碳酸钙对不饱和聚酯片状模塑料力学性能的影响,实验发现:玻纤布增强不饱和聚酯片状模塑料的力学性能比短切玻纤好,随着玻纤含量的增加,不饱和聚酯片状模塑料的拉伸强度先增加,达到一极大值之后减少。碳酸钙填充不饱和聚酯片状模塑料,随着碳酸钙含量的增加,不饱和聚酯片状模塑料的拉伸强度明显降低,弯曲强度增加。     

Enantiomer-based specificity in pheromone communication by two sympatricGnathoirichus species (Coleoptera: Scolytidae)

The aggregation pheromone ofGnathotrichus retusus was isolated and identified as (S)-(+)-sulcatol (6-methyl-5-hepten-2-ol). In laboratory and field experiments,G. retusus responded to (S)-(+)-sulcatol, but not to (±)-sulcatol, which was attractive to the sympatric species,G. sulcatus. G. sulcatus did not respond to optically pure (S)-(+)-sulcatol, but began to respond when 1% (R)-(–)-sulcatol was present in an enantiomeric mixture.Research supported by the National Science Foundation, U.S.A. (Grant BMS-74-13643), and the Natural Sciences and Engineering Research Council of Canada (Co-op grant A0243 and Operating Grant A3881 and A3785).     

Biodesulfurization of dibenzothiophene sulfone by Arthrobacter sp. and studies with oxidized Illinois No. 6 coal

A bacterium identified as Arthrobacter sp. was grown on dibenzothiophene (DBT) sulfone as a sole source of sulfur, producing sulfite and sulfate. Sulfur in DBT sulfone (1.0 mM) was nearly quantitatively converted to sulfate by the organism. The organism could also use DBT sulfone as a sole source of carbon and energy. There was evidence for transient accumulation of benzoic acid in the culture medium after growth of the cells slowed. The DBT sulfoxide analogue 9-fluorenone was converted by resting cells to a product identified as 1,10-dihydroxy-1,10-dihydrofluoren-9-one, suggesting that DBT sulfone may be metabolized via an angular hydroxylation resulting in carbon- sulfur bond cleavage. This strain of Arthrobacter showed no ability to desulfurize oxidized Illinois No. 6 coal.