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996.
锌-锰合金镀层磷化工艺研究 总被引:1,自引:0,他引:1
为进一步提高Zn-M n合金镀层的抗蚀性,采用锌锰系磷化处理Zn-M n合金镀层,研究表明在相同镀层厚度下,Zn-M n合金镀层抗蚀能力是镀锌层的5倍,经磷化后的Zn-M n合金镀层的抗蚀能力是镀锌层的7~8倍。实验结果表明,Zn-M n合金镀层经锌锰系磷化后抗蚀性明显提高。 相似文献
997.
The electrochemical behavior of the Fe(III)/Fe(II)-triethanolamine(TEA) complex redox couple in alkaline medium and influence of the concentration of TEA were investigated. A change of the concentration of TEA mainly produces the following two results. (1) With an increase of the concentration of TEA, the solubility of the Fe(III)-TEA can be increased to 0.6 M, and the solubility of the Fe(II)-TEA is up to 0.4 M. (2) In high concentration of TEA with the ratio of TEA to NaOH ranging from 1 to 6, side reaction peaks on the cathodic main reaction of the Fe(III)-TEA complex at low scan rate can be minimized. The electrode process of Fe(III)-TEA/Fe(II)-TEA is electrochemically reversible with higher reaction rate constant than the uncomplexed species. Constant current charge-discharge shows that applying anodic active materials of relatively high concentrations facilitates the improvement of cell performance. The open-circuit voltage of the Fe-TEA/Br2 cell with the Fe(III)-TEA of 0.4 M, after full charging, is nearly 2.0 V and is about 32% higher than that of the all-vanadium batteries, together with the energy efficiency of approximately 70%. The preliminary exploration shows that the Fe(III)-TEA/Fe(II)-TEA couple is electrochemically promising as negative redox couple for redox flow battery (RFB) application. 相似文献
998.
利用自行搭建的CO2膜吸收实验台,采用聚丙烯(PP)膜组件,以质量分数10%的N-甲基二乙醇胺(MDEA)作为主体胺溶液,添加不同配比的哌嗪(PZ)、乙醇胺(MEA)、甘氨酸钾(PG),考察CO2脱除效率和传质速率的变化,比较不同复配比的复合溶液表面张力以及对PP膜的浸润性,并以10%MDEA+10%PG混合溶液作为吸收液进行长时间实验。结果表明:添加少量的添加剂对MDEA溶液膜吸收CO2均有显著的促进作用,当配比小于0.2时,促进作用大小为PZ>MEA>PG;当配比大于0.2时,促进作用大小为PZ>PG>MEA;PZ和MEA均随着添加配比的增加,溶液表面张力减小,而PG相反;表面张力小的溶液对膜浸润性较强,容易造成膜润湿;添加剂质量分数均为10%时,对膜溶胀性和疏水性以及膜孔结构影响大小为PZ>MEA>PG;在20天内,PG/MDEA混合溶液作用下的CO2脱除效率从89.56%下降为83.09%,对PP的疏水性影响较小,膜组件可以稳定运行。吸收液表面张力对膜吸收法脱除CO2性能的影响显著。所得结果可为膜吸收CO2吸收剂复配提供依据,并可为揭示膜吸收CO2过程中膜润湿导致膜失效的机理以及抑制膜润湿提供实验数据。 相似文献
999.
A method to obtain mechanical properties using a bonded (double) cantilever beam (or three point bend) specimen loaded in a manner to produce pure shear in the adhesive layer is reviewed. A revised mathematical solution which allows for easier interpretation of optimum beam dimensions to the one originally developed by Moussiaux, Cardon and Brinson for the static case is presented. An extension of this solution for a fixed/fixed viscoelastic beam under steady state oscillations developed by Li, Dickie and Morman is also discussed. Previous results using a vibrating beam to determine the complex viscoelastic properties of a bonded beam are reviewed. These results demonstrate conclusively that dynamic mechanical thermal analysis (DMTA) measurements discriminate differences in surface treatments and various environmental conditions. New measurements are presented that indicate the DMTA procedure can be used to quantify damage simulated by imbedded flaws in beams. The procedure is also shown to assess the effects of both humidity and corrosive environments on lap specimens. It is suggested that this technique may ultimately provide a method to quantify the amount of hidden damage in an adhesive joint subjected to fatigue, moisture or corrosive environments. 相似文献
1000.
Activation of plant foliar oxidases by insect feeding reduces nutritive quality of foliage for noctuid herbivores 总被引:12,自引:0,他引:12
G. W. Felton K. Donato R. J. Del Vecchio S. S. Duffey 《Journal of chemical ecology》1989,15(12):2667-2694
The foliage and fruit of the tomato plantLycopersicon esculentum contains polyphenol oxidases (PPO) and peroxidases (POD) that are compartmentally separated from orthodihydroxyphenolic substrates in situ. However, when leaf tissue is damaged by insect feeding, the enzyme and phenolic substrates come in contact, resulting in the rapid oxidation of phenolics to orthoquinones. When the tomato fruitwormHeliothis zea or the beet army-wormSpodoptera exigua feed on tomato foliage, a substantial amount of the ingested chlorogenic acid is oxidized to chlorogenoquinone by PPO in the insect gut. Additionally, the digestive enzymes of the fruitworm have the potential to further activate foliar oxidase activity in the gut. Chlorogenoquinone is a highly reactive electrophilic molecule that readily binds cova-lently to nucleophilic groups of amino acids and proteins. In particular, the —SH and —NH2 groups of amino acids are susceptible to binding or alkylation. In experiments with tomato foliage, the relative growth rate of the fruitworm was negatively correlated with PPO activity. As the tomato plant matures, foliar PPO activity may increase nearly 10-fold while the growth rate of the fruitworm is severely depressed. In tomato fruit, the levels of PPO are highest in small immature fruit but are essentially negligible in mature fruit. The growth rate of larvae on fruit was also negatively correlated with PPO activity, with the fastest larval growth rate occurring when larvae fed on mature fruit. The reduction in larval growth is proposed to result from the alkylation of amino acids/protein byo-quinones, and the subsequent reduction in the nutritive quality of foliage. This alkylation reduces the digestibility of dietary protein and the bioavailability of amino acids. We believe that this mechanism of digestibility reduction may be extrapolatable to other plant-insect systems because of the ubiquitous cooccurrence of PPO and phenolic substrates among vascular plant species. 相似文献