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101.
子午线轮胎出现不久,就采用钢丝带束层代替了纤维带束层,这对于实现子午线轮胎提高使用寿命和改善操纵性能的潜能是必要的。 相似文献
102.
Robert P. Kusy James M. Stuart John Q. Whitley Carl R. Saunders 《Journal of the American Ceramic Society》1993,76(2):299-304
Using laser specular reflectance, the optical rms roughnesses (σ0 'S) of 42 polycrystalline aluminas (PCA's) were determined. From these conventional experimental results, a nomogram was constructed so that single grazing angle (α) measurements could be used to predict σ0 . Subsequently, the nomogram was reassessed using five commercially important PCA's and one single-crystal sapphire (SC). The outcomes were twofold: that this nomogram was valid for PCA's over the range of 0.28 σ0 0.10 μm, but that the nomogram was invalid for SC sapphire. When the conventional experimental method was compared with the nomogram method at three different single-angle values, a 1:1 correspondence was observed for α= 78°, 80°, and 82°. The present noncontact method is advocated for speed and cleanliness, particularly when a quality assurance method is desired. 相似文献
103.
The objective of this research was to study the morphology and properties of PVC–polyurethane blends. Studies on blends of a segmented polyether polyurethane with PVC were carried out utilizing differential scanning calorimetry, Rheovibron, stress–strain, infrared peak position studies, and infrared dichroism experiments. This thermodynamically incompatible system was made kinetically compatible by precipitation from tetrahydrofuran (THF) solutions. THF–dioxane solution casting and melt processing produced an incompatible system. The compatible polyurethane–PVC system contains a well-mixed PVC–polyether matrix phase as evidenced by Tg shifts, orientation characteristics, and infrared peak position changes. The aromatic urethane segments which exhibit microphase separation in the pure polyurethane are not solubilized by blending with PVC by any of sample preparation methods used in this study. 相似文献
104.
Dan I. Enache Dean Barker Jennifer K. Edwards Stuart H. Taylor David W. Knight Albert F. Carley Graham J. Hutchings 《Catalysis Today》2007,122(3-4):407-411
The oxidation of benzyl alcohol with molecular oxygen under solvent-free conditions has been investigated using a range of titania-supported Au–Pd alloy catalysts to examine the effect of the Au–Pd ratio on the conversion and selectivity. The catalysts have been compared at high reaction temperature (160 °C) as well as at 100 °C, to determine the effect on selectivity since at lower reaction temperature the range of by-products that are formed are limited. Under these conditions the 2.5 wt.% Au–2.5 wt.% Pd/TiO2 was found to be the most active catalyst, whereas the Au/TiO2 catalyst demonstrated the highest selectivity to benzaldehyde. Toluene, formed via either a hydrogen transfer process or an oxygen transfer process, was observed as a major by-product under these forcing conditions. 相似文献
105.
Geraniums (Pelargonium xhortorum Bailey) possess a pest-resistance mechanism, based on glandular trichomes and the exudate they produce, that has been shown to be effective against the two-spotted spider mite (Tetranychus urticae Koch). Using an intact plant bioassay, the effectiveness of the resistance mechanism was determined for another potential pest, the foxglove aphid (Acyrthosiphon solani Kaltenbach). Comparisons were made between plant lines previously analyzed for their degree of resistance to mites, as well as their glandular trichome density and trichome exudate production. Over 100 aphid adults were bioassayed on each of the five plant lines used in the experiment. In addition to adult aphid survival, the production and survival of nymphs was determined in this bioassay. The results indicate that plant lines that are resistant to the two-spotted spider mite are also resistant to the foxglove aphid, while lines susceptible to mites are susceptible to the aphids. To evaluate the physical impediment features of the trichome exudate, the behavior of foxglove aphid nymphs was compared on two geranium lines, one a resistant line with high trichome densities and large quantities of exudate and the second a susceptible line with few trichomes and reduced exudate. A third leaf surface type was produced by washing the exudate from resistant leaves using a mildly basic buffer solution prior to the bioassay. Aphid behavior was divided into five categories: feeding or probing, resting, wandering, struggling, and immobilized. On both susceptible leaves and resistant leaves from which the exudate had been removed by washing, the aphids settled quickly and were observed with inserted stylets during most of the observation intervals. In contrast, aphids on the unwashed resistant leaf surfaces often became ensnared in the sticky trichome exudate and had difficulty in settling to probe the leaf. Physical entrapment by glandular trichome exudate appears to be an important aspect of aphid resistance in geraniums. 相似文献
106.
Gudrún V. Skúladóttir Du Shi-Hua Ann E. Brodie Donald J. Reed Rosemary C. Wander 《Lipids》1994,29(5):351-357
Weanling male Sprague-Dawley rats were fed diets for four weeks which differed in their content of n−6 (corn oil; CO) and
n−3 fatty acids (fish oil; FO), but were similar in their content of saturated and monounsaturated fatty acids and vitamin
E. At the end of the four-week feeding period, each dietary group was subdivided into two groups. One group received a single
placebo injection of α-tocopherol-stripped corn oil (TSCO); the other group received a single injection of the free radical
generator, methyl ethyl ketone peroxide (MEKP), in TSCO. Twenty-four hours after injection, the effect of dietary oil and
MEKP treatment on endogenous lipid peroxide (LPO) production (measured as methylene blue formed by the “Determiner LPO” assay),
glutathione (GSH) and vitamin E content, and fatty acid composition of phosphatidylcholine and phosphatidylethanolamine in
heart and liver from unfasted animals were measured. FO-fed rats had significantly heavier hearts and livers, increased levels
of n−3 fatty acids in membrane phospholipids, and higher liver LPO levels than CO-fed rats. MEKP treatment resulted in significantly
lower body weights and liver GSH levels. The data indicate that dietary n−3 fatty acids increase lipid peroxidation in liver
somewhat more than in heart. The study also demonstrates that the effect of induced oxidative stress due to a single dose
of MEKP on lipid peroxide formation and antioxidant status in tissues from unfasted animals was independent of the dietary
oils. 相似文献
107.
Nathan S. Jacobson rew J. Eckel Ajay K. Misra Donald L. Humphrey 《Journal of the American Ceramic Society》1990,73(8):2330-2332
The reactions of a sintered α-SiC with 5% H2 /H2 O/Ar at 1300°C were studied. Thermomchemical modeling indicates that three reaction regions are expected, depending on the initial water vapor or equivalently oxygen content of the gas stream. A high oxygen content ( P (O2 ) > 10−22 atm) leads to a SiO2 formation. This generally forms as a protective film and limits consumption of the SiC (passive oxidation). An intermediate oxygen content (10−22 atm > P (O2 ) > 10−26 atm) leads to SiO and CO formation. These gaseous products can lead to rapid consumption of the SiC (active oxidation). Thermogravimetric studies in this intermediate region gave reaction rates which appear to be controlled by H2 O gas-phase transport to the sample and reacted microstructures showed extensive grain-boundary attack in this region. Finally, a very low oxygen content ( P (O2 ) < 10−26 atm) is thermochemically predicted to lead to selective removal of carbon and formation of free silicon. Experimentally low weight losses and iron silicides are observed in this region. The iron silicides are attributed to reaction of free silicon and iron impurities in the system. 相似文献
108.
Garrett BC Dixon DA Camaioni DM Chipman DM Johnson MA Jonah CD Kimmel GA Miller JH Rescigno TN Rossky PJ Xantheas SS Colson SD Laufer AH Ray D Barbara PF Bartels DM Becker KH Bowen KH Bradforth SE Carmichael I Coe JV Corrales LR Cowin JP Dupuis M Eisenthal KB Franz JA Gutowski MS Jordan KD Kay BD Laverne JA Lymar SV Madey TE McCurdy CW Meisel D Mukamel S Nilsson AR Orlando TM Petrik NG Pimblott SM Rustad JR Schenter GK Singer SJ Tokmakoff A Wang LS Wettig C Zwier TS 《Chemical reviews》2005,105(1):355-390
109.
Metallo-Supramolecular Polymerization: A Route to Easy-To-Process Organic/Inorganic Hybrid Materials
Mark Burnworth Daniel Knapton Stuart J. Rowan Christoph Weder 《Journal of Inorganic and Organometallic Polymers and Materials》2007,17(1):91-103
The self-assembly polymerization of ditopic macromolecules via metal–ligand binding is a facile route for the preparation
of metallo-supramolecular polymers (MSPs). We herein review our recent work focused on the synthesis and investigation of
metallo-supramolecular polymers based on 2,6-bis(1′-methylbenzimidazolyl)pyridine endcapped poly(p-phenylene ethynylene) and poly(p-xylene) macromonomers. These materials are readily solution-processable and display appreciable mechanical properties as
well as other attractive properties such as specific opto/electrical functions or high thermal stability. Our work illustrates
that metallosupramolecular polymerization offers an attractive approach to assemble high-molecular-weight macromolecules from
well-defined, easy to process precursors. Variation of the ditopic ligands and metal ions allows one to easily tailor the
desired properties.
This paper is dedicated to Professor Ian Manners and his scientific accomplishments. 相似文献
110.
Richard H. Harris Vicki J. Boyd Graham J. Hutchings Stuart H. Taylor 《Catalysis Letters》2002,78(1-4):369-372
The effect of water addition on the complete oxidation of benzene and propane VOCs by uranium oxide catalysts has been investigated. Benzene oxidation was studied using a silica supported U3O8 catalyst. Complete oxidation is promoted by the addition of 2.6% water compared with the reactivity when no water is added to the reactant feed. Increasing the water concentration to 12.1% resulted in a suppression of oxidation activity. Investigation of propane oxidation using U3O8 shows a dramatic promotion of activity. Propane conversion was ca. 50% at 600 °C without added water, whilst it increased to 100% at 400 °C with the addition of 2.6% water. A comparison of oxidation activity has been made with Mn2O3, an oxide recognised for complete oxidation. In contrast to the U3O8 catalysts the addition of 2.6% water suppresses the activity of Mn2O3. In situ powder X-ray diffraction studies showed that the bulk U3O8 structure was stable under all the reaction conditions. The origin of the increased activity is not clear but may be due to modification of the catalyst surface and the contribution from new reaction pathways such as steam reforming. 相似文献