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991.
Li-Piin Sung Joan Jasmin Xiaohong Gu Tinh Nguyen Jonathan W. Martin 《Journal of Coatings Technology and Research》2004,1(4):267-276
Laser scanning confocal microscopy (LSCM) has been used to characterize the changes in film thickness and local surface morphology
of polymer coatings during the UV degradation process. With the noninvasive feature of LSCM, one can obtain thickness information
directly and nondestructively at various exposure times without destroying the specimens or deriving the thickness values
from IR measurement by assuming uniform film ablation. Two acrylic polymer coatings were chosen for the study, and the physical
and chemical changes of the two systems at various exposure times were measured and analyzed. Those measurable physical changes
caused by UV exposure include film ablation, formation of pits and other surface defects, and increases in surface roughness.
It was found in both coatings that changes in measured film thickness by LSCM were not correlated linearly to the predicted
thickness loss using the changes in the CH band obtained by the Fourier Transform Infrared (FTIR) spectroscopy measurements
in the later degradation stages. This result suggested it was not a uniform film ablation process during the UV degradation.
At later stages, where surface deformation became severe, surface roughness and profile information using LSCM were also proven
to be useful for analyzing the surface degradation process
Presented at the 81st Annual Meeting of the Federation of Societies for Coatings Technology, November 13–14, 2004 in Philadelphia,
PA. 相似文献
992.
Rare earth exchanged Na–Y zeolites, H-mordenite, K-10 montmorillonite clay and amorphous silica-alumina were effectively employed
for the continuous synthesis of nitriles. Dehydration of benzaldoxime and 4-methoxybenzaldoxime were carried out on these
catalysts at 473 K. Benzonitrile (dehydration product) was obtained in near quantitative yield with benzaldoxime whereas;
4-methoxybenzaldoxime produces both Beckmann rearrangement (4-methoxyphenylformamide) as well as dehydration products (4-methoxy
benzonitrile) in quantitative yields. The production of benzonitrile was near quantitative under heterogeneous reaction conditions.
The optimal protocol allows nitriles to be synthesized in good yields through the dehydration of aldoximes. Time on stream
(TOS) studies show decline in the activity of the catalysts due to neutralization of acid sites by the basic reactant and
product molecules and water formed during the dehydration of aldoximes. 相似文献
993.
994.
介绍CAE技术在模具设计并行工程中应用的基本思路、设计流程和主要特点,并应用Moldflow软件对空气取水机门盖进行CAE分析,以说明CAE技术的并行应用过程。实践证明,CAE技术的并行应用可以提高模具设计质量、缩短模具设计时间,为设计人员提供有效的技术支持,最大限度地发挥CAE的技术优势。 相似文献
995.
Ziqi Sun Yanchun Zhou Jingyang Wang Meishuan Li 《Journal of the American Ceramic Society》2007,90(8):2535-2541
In this paper, the mechanical properties of bulk single-phase γ-Y2 Si2 O7 ceramic are reported. γ-Y2 Si2 O7 exhibits low shear modulus, excellent damage tolerance, and thus has a good machinability ready for metal working tools. To understand the underlying mechanism of machinability, drilling test, Hertzian contact test, and density functional theory (DFT) calculation are employed. Hertzian contact test demonstrates that γ-Y2 Si2 O7 is a "quasi-plastic" ceramic and the intrinsically weak interfaces contribute to its machinability. Crystal structure characteristics and DFT calculations of γ-Y2 Si2 O7 suggest that some weakly bonded planes, which involve Y–O bonds that can be easily broken, are the sources of the low shear deformation resistance and good machinability. 相似文献
996.
周维彪 《化学工业与工程技术》2006,27(5):55-57
对化工槽车自动化洗涤装置失效及其原因进行了分析,指出洗槽机的冲洗和抽水不匹配、洗涤工艺不满足设计要求、硬件出现故障及化学品性质的影响是导致洗涤失效的主要原因,提出了完善现场流程、优化工艺操作、使用自动化控制技术、加强设备维护和保养等解决失效的措施。 相似文献
997.
Summary Polysilanes with an optically active alkoxy group, i.e., (S)-(+)-2-butoxy, (R)-(-)-2-butoxy, (S)-(-)-2-methyl-1-butoxy, and (S)-(+)-3,7-dimethyl-1-octoxy, at the terminal positions, the chiral carbon centers of which were located at the α, β, and γ
positions relative to the oxygen, respectively, were prepared, and the effect of the position of chiral center of the terminal
optically active group on the induction of optical activity in polysilanes was investigated. The circular dichroism (CD) spectra
of these polymers showed positive Cotton signals around 340 nm at temperatures below -20 °C, but the intensities were small,
indicating that the optically active groups at the terminal positions have some ability, albeit small, to induce optical activity
to the polysilanes. Further, the optically active (S)-(+)-2-butoxy and (R)-(-)-2-butoxy groups did not control the helical sense direction of the polymers, despite the different chiral stimuli from
the 2-butoxy groups introduced to the terminal positions. To control the helical structure of polysilanes by the use of optically
active terminal groups, appropriate optically active groups are required. 相似文献
998.
以氮气和水为实验体系,采用均质混合模型,研究微混合器的微通道中两相流通过微通道的压降,并测定了两相流的传质系数.结果表明,微通道当量直径为95.2 μm,气体速率为1.089~4.355 m/s,液体速率为0.006 41~0.170 90 m/s的条件下,均质混合模型计算压降值与实测值吻合良好.气速为1.633~3.484 m/s,液速为0.025 6 m/s时,随着气速增加,传质系数呈递增的趋势.气速为1.633~3.484 m/s,液速为0.019 2 m/s时,随着气速增加,传质系数先增加后降低然后再增加.传质系数对液速变化更为敏感. 相似文献
999.
以酸性白土为催化剂 ,进行异龙脑与愈创木酚的选择性烷基化反应 ,烷基化反应产物异龙脑基愈创木酚在雷尼镍存在下催化加氢 ,得到合成檀香异莰基环己醇混合物。该工艺所得合成檀香中主要成分含量较高 ,香气纯正 ,粘度较大 ,留香时间长 ,有一定的实用价值。 相似文献
1000.
Behavioral cues to deception are instrumental in detecting deception. As one of the primary sources of deception behavior, text has been analyzed at the level of sub-sentence or message but not the discourse of interaction. Additionally, empirical studies on cues to deception in the case of multiple receivers remain nonexistent. To fill these voids, we propose a discourse framework and six hypotheses about deception behaviors in a multi-receiver environment. The deception behaviors are operationalized by discourse features based on an analysis of real-world data. The results of statistical analysis validate the efficacy of discourse features in discriminating deceivers from truth-tellers. 相似文献