A series of sisal based activated carbon fibers were prepared with steam activation at temperature from 750℃ to 900℃. Their pore structures were characterized through their nitrogen adsorption isotherms at 77K using...A series of sisal based activated carbon fibers were prepared with steam activation at temperature from 750℃ to 900℃. Their pore structures were characterized through their nitrogen adsorption isotherms at 77K using different theories. The results showed that t-plot method and DR-plot method could suitably be used to characterize the mesopore structure and the multi-stage distribution of pore size of activated carbon fibers. It also showed that the pore size widens with the increase of activation temperature.展开更多
In order to reveal the reactivity of a functional group in an aromatic compound having two substituents inthe aromatic ring, the hydrogen-isotope exchange reaction (T-H exchange reaction) between tritiated water vapor...In order to reveal the reactivity of a functional group in an aromatic compound having two substituents inthe aromatic ring, the hydrogen-isotope exchange reaction (T-H exchange reaction) between tritiated water vapor(HTO vapor) and 4-amino-2-methylbenzenesulfonic acid (and 5-amino-2-methylphenol) were dynamically observedat 50 (and 70 ) in a gas ℃ ℃ -solid system. Consequently, the fact that the specific activity of the acid increased withtime was obtained, and the T-for-H exchange reaction occurred. By applying the A"-McKay plot method to the dataobserved, the rate constant of each functional group for the reaction was obtained. After the additive property of theHammett’s rule was applied to this work, the new substituent constants were obtained. From the above-mentioned,the following four items have been confirmed: (1) the reactivity of the functional groups can be dynamically analyzed,and the A"-McKay plot method is useful to analyze the reactivity; (2) the additive property of the Hammett’s rule isapplicable to quantitative comparison of the reactivity of the functional groups; (3) the reactivity of the functionalgroups can be simultaneously analyzed by using the A"-McKay plot method in the T-H exchange reaction; and (4) themethod used in this work is also useful for analyzing the reactivity of a certain material having some kinds of functional groups.展开更多
The Varzaghan district at the northwestern margin of the Urumieh–Dokhtar magmatic arc, is considered a promising area for the exploration of porphyry Cu deposits in Iran. In this study we identified mono-and multi-el...The Varzaghan district at the northwestern margin of the Urumieh–Dokhtar magmatic arc, is considered a promising area for the exploration of porphyry Cu deposits in Iran. In this study we identified mono-and multi-element geochemical anomalies associated with Cu–Au–Mo–Bi mineralization in the central parts of the Varzaghan district by applying the concentration–area fractal method. After mono-element geochemical investigations, principal component analysis was applied to ten selected elements in order to acquire a multi-element geochemical signature based on the mineralization-related component. Quantitative comparisons of the obtained fractal-based populations were carried out in accordance with known Cu occurrences using Student's t-values. Then,significant mono-and multi-element geochemical layers were separately combined with related geologic and structural layers to generate prospectivity models, using the fuzzy GAMMA approach. For quantitative evaluation of the effectiveness of different geochemical signatures in final prospectivity models, a prediction-area plot was adapted. The results show that the multi-element geochemical signature of principal component one(PC1) is more effective than mono-element layers in delimiting exploration targets related to porphyry Cu deposits.展开更多
The work described in this paper is a study of gold adsorption on the whole tip surface of iridium field emitter. The study has been carried out using field emission microscope. Changes in electron work function of th...The work described in this paper is a study of gold adsorption on the whole tip surface of iridium field emitter. The study has been carried out using field emission microscope. Changes in electron work function of the iridium substrate which are produced by vapor of deposition of submonolayers of gold in ultra high vacuum have been measured by noting the changes in the slope of Fowler-Nordheim plots. The same procedure for studying the adsorption of copper on iridium?[1] was followed to study the adsorption of gold on iridium. Adsorption of gold was examined on the iridium surface containing the (100) ring which could not be removed thermally.展开更多
The perfluorosulfonic acid （PFSA）/SiO2 composite catalysts were prepared by sol-gel method. Differences concerning pore structure analysis of PFSA/SiO2 catalysts were discussed on the basis of nitrogen adsorption. T...The perfluorosulfonic acid （PFSA）/SiO2 composite catalysts were prepared by sol-gel method. Differences concerning pore structure analysis of PFSA/SiO2 catalysts were discussed on the basis of nitrogen adsorption. Their surface area and pore size distributions were evaluated by Brunauer-Emmett-Teller （BET） and Barrett-Joyner-Halenda （BJH） methods, respectively. The nitrogen adsorption-desorption isotherms associated with adsorption hysteresis of PFSA/SiO2 catalysts were analyzed in detail. The adsorption isotherms of PFSA/SiOe catalysts belonged to Type IV isotherms accompanied by hysteresis loops of Type H1 for PFSA/SiO2 catalysts with content of 5%, 13% and 20% PFSA （PFSA-5, PFSA-13 and PFSA-20）, and the hysteresis loop of Type H2 for PFSA/SiO2 catalyst with 40% PFSA content （PFSA-40）. It indicated that PFSA-5, PFSA-13 and PFSA-20 catalysts had narrow pore size distributions and the well-defined cylindrical pores, while PFSA-40 catalyst had wide pore size distribution and inkbottle-like pores. The pore structure of PFSA-40 catalyst from the analysis of the hysteresis loop was not in agreement with that from BJH method. As an emendation for evaluation of pore size distributions of PFSA/SiOz catalysts, the comparison plots method was introduced, which was helpful to evaluate the pore structure of PFSA/SiO2 catalysts more factually.展开更多
基金Natural Science Foundation Committee of Chinese government (grant No. 50073029) and by Guangdong Provincial Natural Science Foundation (001276)
文摘A series of sisal based activated carbon fibers were prepared with steam activation at temperature from 750℃ to 900℃. Their pore structures were characterized through their nitrogen adsorption isotherms at 77K using different theories. The results showed that t-plot method and DR-plot method could suitably be used to characterize the mesopore structure and the multi-stage distribution of pore size of activated carbon fibers. It also showed that the pore size widens with the increase of activation temperature.
基金Supported by National Basic Research Program of China （973 Program） （2009CB320602）, National Natural Science Foundation of China （60721003, 60736026）, and Changjiang Professorship by Ministry of Education of P. R. China
文摘In order to reveal the reactivity of a functional group in an aromatic compound having two substituents inthe aromatic ring, the hydrogen-isotope exchange reaction (T-H exchange reaction) between tritiated water vapor(HTO vapor) and 4-amino-2-methylbenzenesulfonic acid (and 5-amino-2-methylphenol) were dynamically observedat 50 (and 70 ) in a gas ℃ ℃ -solid system. Consequently, the fact that the specific activity of the acid increased withtime was obtained, and the T-for-H exchange reaction occurred. By applying the A"-McKay plot method to the dataobserved, the rate constant of each functional group for the reaction was obtained. After the additive property of theHammett’s rule was applied to this work, the new substituent constants were obtained. From the above-mentioned,the following four items have been confirmed: (1) the reactivity of the functional groups can be dynamically analyzed,and the A"-McKay plot method is useful to analyze the reactivity; (2) the additive property of the Hammett’s rule isapplicable to quantitative comparison of the reactivity of the functional groups; (3) the reactivity of the functionalgroups can be simultaneously analyzed by using the A"-McKay plot method in the T-H exchange reaction; and (4) themethod used in this work is also useful for analyzing the reactivity of a certain material having some kinds of functional groups.
文摘The Varzaghan district at the northwestern margin of the Urumieh–Dokhtar magmatic arc, is considered a promising area for the exploration of porphyry Cu deposits in Iran. In this study we identified mono-and multi-element geochemical anomalies associated with Cu–Au–Mo–Bi mineralization in the central parts of the Varzaghan district by applying the concentration–area fractal method. After mono-element geochemical investigations, principal component analysis was applied to ten selected elements in order to acquire a multi-element geochemical signature based on the mineralization-related component. Quantitative comparisons of the obtained fractal-based populations were carried out in accordance with known Cu occurrences using Student's t-values. Then,significant mono-and multi-element geochemical layers were separately combined with related geologic and structural layers to generate prospectivity models, using the fuzzy GAMMA approach. For quantitative evaluation of the effectiveness of different geochemical signatures in final prospectivity models, a prediction-area plot was adapted. The results show that the multi-element geochemical signature of principal component one(PC1) is more effective than mono-element layers in delimiting exploration targets related to porphyry Cu deposits.
文摘The work described in this paper is a study of gold adsorption on the whole tip surface of iridium field emitter. The study has been carried out using field emission microscope. Changes in electron work function of the iridium substrate which are produced by vapor of deposition of submonolayers of gold in ultra high vacuum have been measured by noting the changes in the slope of Fowler-Nordheim plots. The same procedure for studying the adsorption of copper on iridium?[1] was followed to study the adsorption of gold on iridium. Adsorption of gold was examined on the iridium surface containing the (100) ring which could not be removed thermally.
基金supported by the National Basic Research Program of China (2003CB615705)Chemistry & Chemical Technology Research Center Plan of Shanghai Huayi Group Company (A200-8608 and A200-80726)
文摘The perfluorosulfonic acid （PFSA）/SiO2 composite catalysts were prepared by sol-gel method. Differences concerning pore structure analysis of PFSA/SiO2 catalysts were discussed on the basis of nitrogen adsorption. Their surface area and pore size distributions were evaluated by Brunauer-Emmett-Teller （BET） and Barrett-Joyner-Halenda （BJH） methods, respectively. The nitrogen adsorption-desorption isotherms associated with adsorption hysteresis of PFSA/SiO2 catalysts were analyzed in detail. The adsorption isotherms of PFSA/SiOe catalysts belonged to Type IV isotherms accompanied by hysteresis loops of Type H1 for PFSA/SiO2 catalysts with content of 5%, 13% and 20% PFSA （PFSA-5, PFSA-13 and PFSA-20）, and the hysteresis loop of Type H2 for PFSA/SiO2 catalyst with 40% PFSA content （PFSA-40）. It indicated that PFSA-5, PFSA-13 and PFSA-20 catalysts had narrow pore size distributions and the well-defined cylindrical pores, while PFSA-40 catalyst had wide pore size distribution and inkbottle-like pores. The pore structure of PFSA-40 catalyst from the analysis of the hysteresis loop was not in agreement with that from BJH method. As an emendation for evaluation of pore size distributions of PFSA/SiOz catalysts, the comparison plots method was introduced, which was helpful to evaluate the pore structure of PFSA/SiO2 catalysts more factually.
