Login In
2004 Volume 20 Issue 10
2004, 20(10): 1175-1178
doi: 10.3866/PKU.WHXB20041001
Abstract:
The membership function(μZ) in fuzzy mathematics has been introduced into molecular point group, and fuzzy point group may be constructed to describe the kind of molecular imperfect symmetry. Furthermore, several concepts such as fuzzy irreducible representation and fuzzy generalized parity for molecular orbital with fuzzy symmetry have been put forward. Exploring the fuzzy symmetry of prototype linear, planar and non-planar molecules, there is a new land of theoretical chemistry before us. Based on this, we have investigated the fuzzy symmetry of simple chemical reactions, revealing the quasi-quantitative characteristics of Woodward-Hoffmann rule.
The membership function(μZ) in fuzzy mathematics has been introduced into molecular point group, and fuzzy point group may be constructed to describe the kind of molecular imperfect symmetry. Furthermore, several concepts such as fuzzy irreducible representation and fuzzy generalized parity for molecular orbital with fuzzy symmetry have been put forward. Exploring the fuzzy symmetry of prototype linear, planar and non-planar molecules, there is a new land of theoretical chemistry before us. Based on this, we have investigated the fuzzy symmetry of simple chemical reactions, revealing the quasi-quantitative characteristics of Woodward-Hoffmann rule.
2004, 20(10): 1179-1181
doi: 10.3866/PKU.WHXB20041002
Abstract:
Carbon-covered alumina (CCA) has been reported to be a promising catalyst support or adsorbent. In the literatures, most of CCAs were prepared by pyrolysis of gaseous hydrocarbon on alumina surface, which was usually not uniformly covered by carbon. In this paper, a simple and novel process has been developed for the preparation of uniform carbon-covered alumina via pyrolysis of sucrose highly dispersed on the surface of alumina. In addition, the coverage and number of carbon layers in CCA can be easily controlled by changing the sucrose content in the precursors and the impregnation times.
Carbon-covered alumina (CCA) has been reported to be a promising catalyst support or adsorbent. In the literatures, most of CCAs were prepared by pyrolysis of gaseous hydrocarbon on alumina surface, which was usually not uniformly covered by carbon. In this paper, a simple and novel process has been developed for the preparation of uniform carbon-covered alumina via pyrolysis of sucrose highly dispersed on the surface of alumina. In addition, the coverage and number of carbon layers in CCA can be easily controlled by changing the sucrose content in the precursors and the impregnation times.
2004, 20(10): 1182-1185
doi: 10.3866/PKU.WHXB20041003
Abstract:
A model analytical chip was prepared by coupling 4 phage antibody clones from mouse and 1 clone from human to the surface of carboxyl-terminated silicon. The lymphocytes from healthy donors were selected as normal cells, while HeLa cells were selected as tumor cell. The whole proteins were labeled by fluorescent dye Cy3 after isolation from lymphocytes and HeLa cells, and then reacted with the analytical chip. A different binding pattern was obtained. Our results showed that the protein chip made of phage antibodies was able to recognize the proteome from different cells.
A model analytical chip was prepared by coupling 4 phage antibody clones from mouse and 1 clone from human to the surface of carboxyl-terminated silicon. The lymphocytes from healthy donors were selected as normal cells, while HeLa cells were selected as tumor cell. The whole proteins were labeled by fluorescent dye Cy3 after isolation from lymphocytes and HeLa cells, and then reacted with the analytical chip. A different binding pattern was obtained. Our results showed that the protein chip made of phage antibodies was able to recognize the proteome from different cells.
2004, 20(10): 1186-1190
doi: 10.3866/PKU.WHXB20041004
Abstract:
The interactions between phosphatidylcholine (PC) and bovine serum albumin (BSA) were studied by FT-IR and FT-Raman spectroscopies, then the influence of lanthanide ion Eu3＋ on the PC/BSA mixture system was discussed. In the region of 900～1300 cm－1, FT-IR spectra showed that the bands of P=O, P-O-C and C－O of the PC/BSA mixture were shifted compared with the corresponding bands of pure PC and BSA, and the more content of BSA (relative to the content of PC) the greater shift was observed. The curve-fitting result of amide I band indicated that an increase of α-helix fragments in the PC/BSA mixture. FT-Raman spectra showed that the CH stretching bands in the PC/BSA mixture were varied, which indicated a disturbance of PC′s long chains in the mixture system. After Eu ion was added into the PC/BSA system, the P=O stretching vibration bands in FT-IR spectra shifted from 1241 to 1208 cm－1. This helped us to conclude that the Eu ions bind to the P=O group in the PC/BSA mixture.
The interactions between phosphatidylcholine (PC) and bovine serum albumin (BSA) were studied by FT-IR and FT-Raman spectroscopies, then the influence of lanthanide ion Eu3＋ on the PC/BSA mixture system was discussed. In the region of 900～1300 cm－1, FT-IR spectra showed that the bands of P=O, P-O-C and C－O of the PC/BSA mixture were shifted compared with the corresponding bands of pure PC and BSA, and the more content of BSA (relative to the content of PC) the greater shift was observed. The curve-fitting result of amide I band indicated that an increase of α-helix fragments in the PC/BSA mixture. FT-Raman spectra showed that the CH stretching bands in the PC/BSA mixture were varied, which indicated a disturbance of PC′s long chains in the mixture system. After Eu ion was added into the PC/BSA system, the P=O stretching vibration bands in FT-IR spectra shifted from 1241 to 1208 cm－1. This helped us to conclude that the Eu ions bind to the P=O group in the PC/BSA mixture.
2004, 20(10): 1191-1195
doi: 10.3866/PKU.WHXB20041005
Abstract:
Nanoscale titanium dioxide thin films were prepared at room temperature by RF magnetron sputtering process and annealed at different temperatures. Electrochemical characteristic of ITO/TiO2 electrode under UV irradiation was investigated using the method of cyclic voltammetry, and photo-induced hydrophilicity and photocatalytic activity of TiO2 thin films have been studied. It shows that the as deposited TiO2 thin films are in amorphous state and the anatase phase forms when anneal temperature is over 400 ℃. New oxidative peaks were observed when the TiO2 electrode was irradiated by 254 nm UV light for a certain time. The peak current increased with the increase of UV irradiation time. The oxidative peaks at 0.1 V and 0.05 V were observed for TiO2 electrode annealed at 300 and 500 ℃,respectively, and both were observed for TiO2 electrode annealed at 400 ℃. It is assumed that the new oxidative peak belongs to the oxidation of Ti3＋, which was formed during the UV illumination, and the changes of hydrophilicity of the films may be related with the formation of Ti3＋ on the surface when the films were irradiated by UV light. The TiO2 thin films annealed at 400 ℃ exhibit a od hydrophilicity and photocatalytic activity.
Nanoscale titanium dioxide thin films were prepared at room temperature by RF magnetron sputtering process and annealed at different temperatures. Electrochemical characteristic of ITO/TiO2 electrode under UV irradiation was investigated using the method of cyclic voltammetry, and photo-induced hydrophilicity and photocatalytic activity of TiO2 thin films have been studied. It shows that the as deposited TiO2 thin films are in amorphous state and the anatase phase forms when anneal temperature is over 400 ℃. New oxidative peaks were observed when the TiO2 electrode was irradiated by 254 nm UV light for a certain time. The peak current increased with the increase of UV irradiation time. The oxidative peaks at 0.1 V and 0.05 V were observed for TiO2 electrode annealed at 300 and 500 ℃,respectively, and both were observed for TiO2 electrode annealed at 400 ℃. It is assumed that the new oxidative peak belongs to the oxidation of Ti3＋, which was formed during the UV illumination, and the changes of hydrophilicity of the films may be related with the formation of Ti3＋ on the surface when the films were irradiated by UV light. The TiO2 thin films annealed at 400 ℃ exhibit a od hydrophilicity and photocatalytic activity.
2004, 20(10): 1196-1199
doi: 10.3866/PKU.WHXB20041006
Abstract:
The pH of bile is 6～8 in human gallbladder. The changes in pH will probably effect bile composition, which is important for gallstone formation. But little attention has been given to the influence of H＋ on bile salts aggregates in aqueous solution. Our work focused on the changes of NaDC aggregates with adding H＋ by using pH titration, FT-IR, UV-Vis and QELS (quasi-elastic light-scattering spectrometer) spectroscopies. The following conclusions are given: (1) With addition of H＋ into NaDC aqueous solution above the cmc, The aggregation of NaDC micellar changes gradually into protonated micellar aggregates, secondary or mixed aggregates, and eventually gel-like precipitates.(2) The strong H-bond with the acid salt mode induces protonated micellar aggregation to connect with primary micelles of NaDC. (3) Therefore, aqueous micellar NaDC has a buffering capacity and can increase the solubility of HDC.
The pH of bile is 6～8 in human gallbladder. The changes in pH will probably effect bile composition, which is important for gallstone formation. But little attention has been given to the influence of H＋ on bile salts aggregates in aqueous solution. Our work focused on the changes of NaDC aggregates with adding H＋ by using pH titration, FT-IR, UV-Vis and QELS (quasi-elastic light-scattering spectrometer) spectroscopies. The following conclusions are given: (1) With addition of H＋ into NaDC aqueous solution above the cmc, The aggregation of NaDC micellar changes gradually into protonated micellar aggregates, secondary or mixed aggregates, and eventually gel-like precipitates.(2) The strong H-bond with the acid salt mode induces protonated micellar aggregation to connect with primary micelles of NaDC. (3) Therefore, aqueous micellar NaDC has a buffering capacity and can increase the solubility of HDC.
2004, 20(10): 1200-1203
doi: 10.3866/PKU.WHXB20041007
Abstract:
Silver nanoparticles were synthesized by the method of γ-irradiation in the water-in-oil (w/o) microemulsion composed of SDS (sodium dodecyl sulfate), n-hexanol, cyclohexane and aqueous solution. Light emission in different formation stages was observed, and we found that in our case it was mainly the clusters but not nanoparticles that caused the photoluminescence, with the proof from the absorption spectra and transmission electron microscope (TEM). And it was also suggested that electron and/or hole states can be perturbed by surface states, as indicated by the dependence of the emission spectrum on the nature of the surface. Silver nanoparticles can self-assemble to form the superlattics due to the very narrow size distribution.
Silver nanoparticles were synthesized by the method of γ-irradiation in the water-in-oil (w/o) microemulsion composed of SDS (sodium dodecyl sulfate), n-hexanol, cyclohexane and aqueous solution. Light emission in different formation stages was observed, and we found that in our case it was mainly the clusters but not nanoparticles that caused the photoluminescence, with the proof from the absorption spectra and transmission electron microscope (TEM). And it was also suggested that electron and/or hole states can be perturbed by surface states, as indicated by the dependence of the emission spectrum on the nature of the surface. Silver nanoparticles can self-assemble to form the superlattics due to the very narrow size distribution.
2004, 20(10): 1204-1210
doi: 10.3866/PKU.WHXB20041008
Abstract:
A series of 50 5-arylhydantoins were subjected to a quantitative structure-activity relationship(QSAR) study. Two different QSAR methods, comparative molecular field analysis (CoMFA) and hologram QSAR (HQSAR), were compared in terms of their potential for predictability. Both models had od predictability and yielded q2 values 0.815 (CoMFA) and 0.893(HQSAR), respectively. HQSAR does not require the generation of a 3D structure of molecule; therefore it is faster than CoMFA in data processing. The models will be useful to speculate the combining mode between the CSP and the analogues as well as to quantitatively prognosticate the separation of other 5-arylhydanoin analogues on Pirkle type chiral stationary phases.
A series of 50 5-arylhydantoins were subjected to a quantitative structure-activity relationship(QSAR) study. Two different QSAR methods, comparative molecular field analysis (CoMFA) and hologram QSAR (HQSAR), were compared in terms of their potential for predictability. Both models had od predictability and yielded q2 values 0.815 (CoMFA) and 0.893(HQSAR), respectively. HQSAR does not require the generation of a 3D structure of molecule; therefore it is faster than CoMFA in data processing. The models will be useful to speculate the combining mode between the CSP and the analogues as well as to quantitatively prognosticate the separation of other 5-arylhydanoin analogues on Pirkle type chiral stationary phases.
2004, 20(10): 1211-1215
doi: 10.3866/PKU.WHXB20041009
Abstract:
The use of methyl-tert-butyl ether (MTBE),which is a gasoline additive to enhance the octane rating of gasoline, has resulted in increasing pollution of groundwater. Most of the conventional treatment technologies are inefficient or expensive due to its high solubility in water and low Henry's law constant. To find an ecology friendly and inexpensive method for MTBE remediation, homemade titanium dioxide (TiO2) was used as a photocatalyst, and the photocatalytic degradation of MTBE in a batch TiO2 slurry reactor was studied by using Purge ＆ Trap GC-MS-SIM and IC. It was showed that MTBE could be photocatalytically transformed to innocuous products and mineralized ultimately in oxygenated TiO2 slurries. The major by-products of this reaction have been identified as t-butyl formate, t-butyl alcohol and acetone, all of which are also readily degraded photocatalytically, albeit at different rates. Based on identification of intermediates and products, the first step in the destruction of MTBE is thought to be abstraction of an α-hydrogen by •OH and a reaction scheme is proposed.
The use of methyl-tert-butyl ether (MTBE),which is a gasoline additive to enhance the octane rating of gasoline, has resulted in increasing pollution of groundwater. Most of the conventional treatment technologies are inefficient or expensive due to its high solubility in water and low Henry's law constant. To find an ecology friendly and inexpensive method for MTBE remediation, homemade titanium dioxide (TiO2) was used as a photocatalyst, and the photocatalytic degradation of MTBE in a batch TiO2 slurry reactor was studied by using Purge ＆ Trap GC-MS-SIM and IC. It was showed that MTBE could be photocatalytically transformed to innocuous products and mineralized ultimately in oxygenated TiO2 slurries. The major by-products of this reaction have been identified as t-butyl formate, t-butyl alcohol and acetone, all of which are also readily degraded photocatalytically, albeit at different rates. Based on identification of intermediates and products, the first step in the destruction of MTBE is thought to be abstraction of an α-hydrogen by •OH and a reaction scheme is proposed.
2004, 20(10): 1216-1220
doi: 10.3866/PKU.WHXB20041010
Abstract:
Copper(II) paratolylsulfonate [Cu(p-OTs)]2 has been synthesized and characterized by X-ray crystal structure analysis. The electrochemical parameters of Cu(p-OTs)2 in H2O, CH3OH and DMF have been studied on platinum electrode, respectively. Different reaction mechanisms in different solvents are found. The electrochemical reduction of Cu(II) to Cu proceeds by two one-electron steps in H2O. However, it is a one two-electron process in CH3OH and DMF.
Copper(II) paratolylsulfonate [Cu(p-OTs)]2 has been synthesized and characterized by X-ray crystal structure analysis. The electrochemical parameters of Cu(p-OTs)2 in H2O, CH3OH and DMF have been studied on platinum electrode, respectively. Different reaction mechanisms in different solvents are found. The electrochemical reduction of Cu(II) to Cu proceeds by two one-electron steps in H2O. However, it is a one two-electron process in CH3OH and DMF.
2004, 20(10): 1221-1225
doi: 10.3866/PKU.WHXB20041011
Abstract:
Amorphous, monoclinic and tetra nal zirconia with pure crystal phase were prepared from the same zirconium precursor, and then characterized by XRD,SEM,NH3-TPD,CO2-TPD and FT-IR techniques to determine and compare the different surface chemical properties of the three zirconia polymorphs. The results showed that different surface hydroxyl groups presented on the three-zirconia polymorphs. Bibridged hydroxyl only existed on tetra nal zirconia and amorphous showed obvious H-bond hydroxyl while two type of tribridged hydroxyl existed on monoclinic zirconia surface. Meanwhile the acidity-basicity properties were different on the three-zirconia polymorphs.
Amorphous, monoclinic and tetra nal zirconia with pure crystal phase were prepared from the same zirconium precursor, and then characterized by XRD,SEM,NH3-TPD,CO2-TPD and FT-IR techniques to determine and compare the different surface chemical properties of the three zirconia polymorphs. The results showed that different surface hydroxyl groups presented on the three-zirconia polymorphs. Bibridged hydroxyl only existed on tetra nal zirconia and amorphous showed obvious H-bond hydroxyl while two type of tribridged hydroxyl existed on monoclinic zirconia surface. Meanwhile the acidity-basicity properties were different on the three-zirconia polymorphs.
2004, 20(10): 1226-1232
doi: 10.3866/PKU.WHXB20041012
Abstract:
The interactions between α-Al2O3 nanoparticles and metal ions or electrode surface during composite electrodeposition process were investigated by Zeta potential and electrochemical methods.Zeta potential measurements reveal that Al2O3 nanoparticles have a stronger tendency to adsorb Co2＋ on their surface than Ni2＋ in sulfamate electrolytes. Steady-state polarization and electrochemical impedance spectroscopy (EIS) indicate that the effect of Al2O3 nanoparticles on the Co-Ni electrochemical codeposition in different electrolytes ([Co2＋]/[Ni2＋]=1/5 and 5/1) is quite contrary. In nickel-rich electrolytes ([Co2＋]/[Ni2＋]=1/5),the Al2O3 particles have an inhibitory action on the reduction of Ni2＋, while in cobalt-rich electrolytes ([Co2＋]/[Ni2＋]=5/1), Al2O3 particles activate the reduction of Co2＋. That nanoparticles exhibit different influence on the reduction of Co2＋ and Ni2＋ were explained by considering the adsorption of metal ions on nanoparticle surface. Moreover, it can be seen from EIS that besides one capacitive loop at high frequency and one inductive loop at low frequency, the introduction of Al2O3 particles leads to exhibit a further inductive loop at low frequency. According to the simulated results, the electrochemical codeposition mechanism and simulated impedance parameters were analyzed and in od agreement with the experimental results.
The interactions between α-Al2O3 nanoparticles and metal ions or electrode surface during composite electrodeposition process were investigated by Zeta potential and electrochemical methods.Zeta potential measurements reveal that Al2O3 nanoparticles have a stronger tendency to adsorb Co2＋ on their surface than Ni2＋ in sulfamate electrolytes. Steady-state polarization and electrochemical impedance spectroscopy (EIS) indicate that the effect of Al2O3 nanoparticles on the Co-Ni electrochemical codeposition in different electrolytes ([Co2＋]/[Ni2＋]=1/5 and 5/1) is quite contrary. In nickel-rich electrolytes ([Co2＋]/[Ni2＋]=1/5),the Al2O3 particles have an inhibitory action on the reduction of Ni2＋, while in cobalt-rich electrolytes ([Co2＋]/[Ni2＋]=5/1), Al2O3 particles activate the reduction of Co2＋. That nanoparticles exhibit different influence on the reduction of Co2＋ and Ni2＋ were explained by considering the adsorption of metal ions on nanoparticle surface. Moreover, it can be seen from EIS that besides one capacitive loop at high frequency and one inductive loop at low frequency, the introduction of Al2O3 particles leads to exhibit a further inductive loop at low frequency. According to the simulated results, the electrochemical codeposition mechanism and simulated impedance parameters were analyzed and in od agreement with the experimental results.
2004, 20(10): 1233-1238
doi: 10.3866/PKU.WHXB20041013
Abstract:
Ni-Mo bi-metallic oxide catalyst prepared by a sol-gel method has been used to synthesize high quality multi-walled carbon nanotube bundles with high purity by catalytic decomposition of CH4. The experiment reveals that the prepared catalysts have high activity and high efficiency. After reaction for 2 h, the quantity of synthesized MWNTs is over 80 times of the pristine catalysts. Scanning electron microscopy (SEM), transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HRTEM), thermal gravimetric analysis (TGA), powder X-ray diffraction (XRD) and laser Raman spectroscopy have been performed to characterize the synthesized MWNT bundles. The results show that the synthesized MWNT bundles have a diameter distribution about 10～20 nm. The longer the reaction time is, the graphitization degree of the synthesized MWNT bundles is. After reaction for 1 h, the MWNT bundles with a high purity of more than 97％can be obtained. With a simple enlarged process, a single furnace can produce over 40 g MWNTs for 1 g of catalyst in 30 min.
Ni-Mo bi-metallic oxide catalyst prepared by a sol-gel method has been used to synthesize high quality multi-walled carbon nanotube bundles with high purity by catalytic decomposition of CH4. The experiment reveals that the prepared catalysts have high activity and high efficiency. After reaction for 2 h, the quantity of synthesized MWNTs is over 80 times of the pristine catalysts. Scanning electron microscopy (SEM), transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HRTEM), thermal gravimetric analysis (TGA), powder X-ray diffraction (XRD) and laser Raman spectroscopy have been performed to characterize the synthesized MWNT bundles. The results show that the synthesized MWNT bundles have a diameter distribution about 10～20 nm. The longer the reaction time is, the graphitization degree of the synthesized MWNT bundles is. After reaction for 1 h, the MWNT bundles with a high purity of more than 97％can be obtained. With a simple enlarged process, a single furnace can produce over 40 g MWNTs for 1 g of catalyst in 30 min.
2004, 20(10): 1253-1257
doi: 10.3866/PKU.WHXB20041018
Abstract:
Typical ferroelectricity in Langmuir-Blodgett multilayers prepared from hemicyanine dyes has been demonstrated by observed ferroelectric hysteresis loop. Their ferroelectric properties are found to be thickness dependent. The coercive field decreased with increasing film thickness monotonously and may be approximated by a power law Ec∝N－4/3 in the range from 30 to 200 nm, which is coincident with other conventional ferroelectric materials. The optimum thickness of hemicyanine LB multiplayer is about 60 nm and their optimum value as ferroelectric storage-devices has the same order of magnitude as P(VdF-TrEE)(n :n=70 :30).
Typical ferroelectricity in Langmuir-Blodgett multilayers prepared from hemicyanine dyes has been demonstrated by observed ferroelectric hysteresis loop. Their ferroelectric properties are found to be thickness dependent. The coercive field decreased with increasing film thickness monotonously and may be approximated by a power law Ec∝N－4/3 in the range from 30 to 200 nm, which is coincident with other conventional ferroelectric materials. The optimum thickness of hemicyanine LB multiplayer is about 60 nm and their optimum value as ferroelectric storage-devices has the same order of magnitude as P(VdF-TrEE)(n :n=70 :30).
2004, 20(10): 1258-1261
doi: 10.3866/PKU.WHXB20041019
Abstract:
The functional polymers of 4-dodecylbenzenesulfonic acid-doped polyaniline (PANI-DBSA) and poly(2-methoxy-5-(2’-ethyl-hexloxy)-p-phenylene-vinylene) (MEH-PPV) are adopted as film formation materials, and two kinds of ordered honeycomb nano/micro structures are successfully fabricated by water assisted self-assembly method using water droplet as template. The film morphology, electric and luminescent properties are studied in detail by atomic force microscopy and confocal fluorescent microscopy.
The functional polymers of 4-dodecylbenzenesulfonic acid-doped polyaniline (PANI-DBSA) and poly(2-methoxy-5-(2’-ethyl-hexloxy)-p-phenylene-vinylene) (MEH-PPV) are adopted as film formation materials, and two kinds of ordered honeycomb nano/micro structures are successfully fabricated by water assisted self-assembly method using water droplet as template. The film morphology, electric and luminescent properties are studied in detail by atomic force microscopy and confocal fluorescent microscopy.
2004, 20(10): 1262-1266
doi: 10.3866/PKU.WHXB20041020
Abstract:
The direct electron transfer of different heme proteins immobilized on mesoporous molecular sieves was studied. The direct electrochemistry of horseradish peroxidase (HRP), hemoglobin (Hb) and myoglobin (Mb) immobilized on hexa nal mesoporous silica (HMS) was described, respectively. The immobilized heme proteins at modified glassy carbon electrodes (GCE) showed od direct electrochemical behaviors, which depended on the specific properties of the HMS. Two couples of redox peaks corresponding to the Fe(III) to Fe(II) conversion of the proteins intercalated in the mesopores and adsorbed on the surface of the HMS in 0.1 mol•L－1, pH 7.0 PBS (phosphate-buffered saline), respectively, were observed. The amount of proteins intercalated in the mesopores of HMS was proved to be related to the porous size. The result showed the electrode processes to be surface-controlled electrode processes with a single proton transfer. The interactions between proteins and HMS were investigated by using FT-IR, N2 adsorption isotherms and electrochemical methods, and the new biosensors of hydrogen peroxide (H2O2) and nitrite (NO2－) were constructed. These works extended the application of HMS in immobilizing protein, the direct electron transfer of protein and the construction of reagentless biosensors.
The direct electron transfer of different heme proteins immobilized on mesoporous molecular sieves was studied. The direct electrochemistry of horseradish peroxidase (HRP), hemoglobin (Hb) and myoglobin (Mb) immobilized on hexa nal mesoporous silica (HMS) was described, respectively. The immobilized heme proteins at modified glassy carbon electrodes (GCE) showed od direct electrochemical behaviors, which depended on the specific properties of the HMS. Two couples of redox peaks corresponding to the Fe(III) to Fe(II) conversion of the proteins intercalated in the mesopores and adsorbed on the surface of the HMS in 0.1 mol•L－1, pH 7.0 PBS (phosphate-buffered saline), respectively, were observed. The amount of proteins intercalated in the mesopores of HMS was proved to be related to the porous size. The result showed the electrode processes to be surface-controlled electrode processes with a single proton transfer. The interactions between proteins and HMS were investigated by using FT-IR, N2 adsorption isotherms and electrochemical methods, and the new biosensors of hydrogen peroxide (H2O2) and nitrite (NO2－) were constructed. These works extended the application of HMS in immobilizing protein, the direct electron transfer of protein and the construction of reagentless biosensors.
2004, 20(10): 1239-1241
doi: 10.3866/PKU.WHXB20041014
Abstract:
A cost effective and convenient method for preparing nanopowders of Fe-Co alloy has been developed. The finely divided powders of Fe-Co alloy in the form of solid-solution were obtained in the FeSO4•(NH4)2SO4 and CoSO4•(NH4)2SO4 mixed solution by the reduction of aluminum powders at 40 ℃ and pH～3.The product of Fe-Co alloy was identified by XRD method and the calculated size of these nanoparticles was about 15 nm. Meanwhile, the compositions of obtained samples were analyzed by ICP-AES method. Experiment indicated that the composition of the alloy could be easily controlled by changing the mass ratio of Fe2＋:Co2＋ in the solution.
A cost effective and convenient method for preparing nanopowders of Fe-Co alloy has been developed. The finely divided powders of Fe-Co alloy in the form of solid-solution were obtained in the FeSO4•(NH4)2SO4 and CoSO4•(NH4)2SO4 mixed solution by the reduction of aluminum powders at 40 ℃ and pH～3.The product of Fe-Co alloy was identified by XRD method and the calculated size of these nanoparticles was about 15 nm. Meanwhile, the compositions of obtained samples were analyzed by ICP-AES method. Experiment indicated that the composition of the alloy could be easily controlled by changing the mass ratio of Fe2＋:Co2＋ in the solution.
2004, 20(10): 1242-1244
doi: 10.3866/PKU.WHXB20041015
Abstract:
At low temperature(about 250 ℃), the mixture of polyvinyl alcohol(PVA)and purified carbon nanotubes (CNTs) was heated in the air to study the effect of PVA on the morphologies of the carbon nanotubes. The TEM pictures show that the top of the carbon nanotubes is opened, and the intertwisting carbon nanotubes are cut into short carbon nanotubes. The quantity of the short nanotubes increases with the time consuming. The oxidation and decoration of carbon nanotubes by polyvinyl alcohol have been demonstrated in these experiments. Based on these results, the mechanism of the oxidation and decoration is proposed, which indicates that one or more products generated from the decomposition of polyvinyl alcohol play an important role in the process of the reaction.
At low temperature(about 250 ℃), the mixture of polyvinyl alcohol(PVA)and purified carbon nanotubes (CNTs) was heated in the air to study the effect of PVA on the morphologies of the carbon nanotubes. The TEM pictures show that the top of the carbon nanotubes is opened, and the intertwisting carbon nanotubes are cut into short carbon nanotubes. The quantity of the short nanotubes increases with the time consuming. The oxidation and decoration of carbon nanotubes by polyvinyl alcohol have been demonstrated in these experiments. Based on these results, the mechanism of the oxidation and decoration is proposed, which indicates that one or more products generated from the decomposition of polyvinyl alcohol play an important role in the process of the reaction.
2004, 20(10): 1245-1248
doi: 10.3866/PKU.WHXB20041016
Abstract:
A new anionic Gemini surfactant has been synthesized by the following method: firstly a “dimer" was prepared by the reaction of nonylphenol（NP）and 1,4-dibromobutane in the presence of a catalyst. The “dimer” was sulfonated with chlorosulfonic acid and then neutralized with sodium hydroxide to obtain the title-compound. Micellization of the Gemini surfactant was investigated by using drop volume method. Result showed that the critical micelle concentration (cmc) of the Gemini surfactant has a much lower value compared with those conventional monomeric surfactants. The aggregation number (N) of the micelle was determined with intrinsic fluorescence quenching method as a function of concentration. N es through a maximum upon increasing the concentration of the Gemini surfactant, meanwhile the formation of liquid crystal is observed.
A new anionic Gemini surfactant has been synthesized by the following method: firstly a “dimer" was prepared by the reaction of nonylphenol（NP）and 1,4-dibromobutane in the presence of a catalyst. The “dimer” was sulfonated with chlorosulfonic acid and then neutralized with sodium hydroxide to obtain the title-compound. Micellization of the Gemini surfactant was investigated by using drop volume method. Result showed that the critical micelle concentration (cmc) of the Gemini surfactant has a much lower value compared with those conventional monomeric surfactants. The aggregation number (N) of the micelle was determined with intrinsic fluorescence quenching method as a function of concentration. N es through a maximum upon increasing the concentration of the Gemini surfactant, meanwhile the formation of liquid crystal is observed.
2004, 20(10): 1249-1252
doi: 10.3866/PKU.WHXB20041017
Abstract:
Olivine LiMnPO4 was synthesized at 600 ℃ and 800 ℃ by the method of solid-state reaction combining with the addition of carbon black and ball-milling of reagents and precursors. Structure, surface morphology and charge/discharge performance of LiMnPO4 were characterized by X-ray diffraction (XRD), scanning electron microscope (SEM), and electrochemical measurement, respectively. Sample synthesized at 600 ℃ by ball-milling of reagents for 24 h and precursors for 12 h contains impurities and large, densely sintered blocks .Pure olivine LiMnPO4 with large particle size is obtained at 800 ℃ by the same ball-milling process. It is shown that these materials can′t charge or discharge effectively in the electrochemical tests. On the contrary, sample prepared at 600 ℃ by ball-milling of reagents for 36 h and precursors for 24 h presents pure phase with small and almost identical particles size (about 100～200 nm). The initial discharge capacity of this sample is approximately 100 mAh•g－1. Mixing of the agents and the precursors and the choice of sintering temperature are two important factors to obtain pure olivine LiMnPO4 with reversible charge-discharge capacity.
Olivine LiMnPO4 was synthesized at 600 ℃ and 800 ℃ by the method of solid-state reaction combining with the addition of carbon black and ball-milling of reagents and precursors. Structure, surface morphology and charge/discharge performance of LiMnPO4 were characterized by X-ray diffraction (XRD), scanning electron microscope (SEM), and electrochemical measurement, respectively. Sample synthesized at 600 ℃ by ball-milling of reagents for 24 h and precursors for 12 h contains impurities and large, densely sintered blocks .Pure olivine LiMnPO4 with large particle size is obtained at 800 ℃ by the same ball-milling process. It is shown that these materials can′t charge or discharge effectively in the electrochemical tests. On the contrary, sample prepared at 600 ℃ by ball-milling of reagents for 36 h and precursors for 24 h presents pure phase with small and almost identical particles size (about 100～200 nm). The initial discharge capacity of this sample is approximately 100 mAh•g－1. Mixing of the agents and the precursors and the choice of sintering temperature are two important factors to obtain pure olivine LiMnPO4 with reversible charge-discharge capacity.
2004, 20(10): 1267-1270
doi: 10.3866/PKU.WHXB20041021
Abstract:
In this paper,glucose oxidase( D) electrodes were fabricated by alternative adsorption of oppositely charged polycations (poly(dimethydiallyammonium)hydrochloride, PDDA) and enzymes on Au modified by 3-mercapto-1-propanesulfonic acid, sodium salt (MPS). The concentration of glucose was detected by cyclic voltammetry via ferrocene monocarboxylic acid as mediator. A linear relationship existed between peak current and concentration of glucose in the range 0.55～6.63 mmol•L－1. The effect of pH on the response current of electroroxidation of glucose by D had been studied and the optimum pH was 7.0.In addition, the biosensor showed od reproducibility for the determination of glucose and the relative standard deviation was 2.4％.
In this paper,glucose oxidase( D) electrodes were fabricated by alternative adsorption of oppositely charged polycations (poly(dimethydiallyammonium)hydrochloride, PDDA) and enzymes on Au modified by 3-mercapto-1-propanesulfonic acid, sodium salt (MPS). The concentration of glucose was detected by cyclic voltammetry via ferrocene monocarboxylic acid as mediator. A linear relationship existed between peak current and concentration of glucose in the range 0.55～6.63 mmol•L－1. The effect of pH on the response current of electroroxidation of glucose by D had been studied and the optimum pH was 7.0.In addition, the biosensor showed od reproducibility for the determination of glucose and the relative standard deviation was 2.4％.
2004, 20(10): 1271-1274
doi: 10.3866/PKU.WHXB20041022
Abstract:
A new coupled transport system, using calixarene derivatives as the cationic carriers and nickel complex of multi-sulfur 1,2-dithiolene[Ni(dmit)2] as the electron carrier, was reported in this paper. The reducting phase (source phase) contains sodium dithionite as reducing agent; the oxidation phase (receiving phase) contains potassium ferricyanide as oxidizing agent. Driven by the redox gradient, the coupled transports of electrons and metal cations were thus realized. The impacts of the cationic carriers and the electronic carrier on the coupled transport were studied. In addition, the mechanism of transport of electron-cation symport was discussed.
A new coupled transport system, using calixarene derivatives as the cationic carriers and nickel complex of multi-sulfur 1,2-dithiolene[Ni(dmit)2] as the electron carrier, was reported in this paper. The reducting phase (source phase) contains sodium dithionite as reducing agent; the oxidation phase (receiving phase) contains potassium ferricyanide as oxidizing agent. Driven by the redox gradient, the coupled transports of electrons and metal cations were thus realized. The impacts of the cationic carriers and the electronic carrier on the coupled transport were studied. In addition, the mechanism of transport of electron-cation symport was discussed.
2004, 20(10): 1275-1280
doi: 10.3866/PKU.WHXB20041023
Abstract:
In this paper, we discussed the concept of “surface ions” and the differences between “surface ions”method and traditional “subphase ions” method. The “surface ions” method is a newly developed technology on functional Langmuir-Blodgett(LB) film fabrication and allows water-insoluble, non-amphiphilic functional molecules to be applied in fabricating LB films. Also we discussed the monolayer-formation mechanism of two different types of “surface ions”: Ru chelates and metal β-diketone complex. In the end, we introduced“surface ions” method’s application in the supramolecular systems. The components in Langmuir monolayer and LB films can be controlled and adjusted easily. “Surface ions” method can also be applied in multi-component functional molecular systems.
In this paper, we discussed the concept of “surface ions” and the differences between “surface ions”method and traditional “subphase ions” method. The “surface ions” method is a newly developed technology on functional Langmuir-Blodgett(LB) film fabrication and allows water-insoluble, non-amphiphilic functional molecules to be applied in fabricating LB films. Also we discussed the monolayer-formation mechanism of two different types of “surface ions”: Ru chelates and metal β-diketone complex. In the end, we introduced“surface ions” method’s application in the supramolecular systems. The components in Langmuir monolayer and LB films can be controlled and adjusted easily. “Surface ions” method can also be applied in multi-component functional molecular systems.
2004, 20(10): 1281-1286
doi: 10.3866/PKU.WHXB20041024
Abstract:
Four methods to prepare thin films of charge-transfer complexes have been reviewed and the structural characterization of the related CT films was studied. In the LB films of the complex of N,N,N’,N’-tetramethylbenzidine (N-TMB) and 2-octadecyl-7,7,8,8- tetracyanoquinodimethane (C18H37TCNQ), the chromophore planes for both C18H37TCNQ and N-TMB are nearly parallel to the substrate surface while the hydrocarbon chain is considerably tilted with respect to the substrate normal. By dipping the mixed LB films of stearic acid and C18H37TCNQ into a petroleum ether solution of 3,3’,5,5’-tetramethylbenzidine(TMB), the thin films of charge-transfer complex can also be formed. In that case, the chromophore plane of TMB is nearly perpendicular to the substrate surface with its long axis lying on the substrate. If dipping LB films of pure C18H37TCNQ into a petroleum ether solution of TMB, we can also obtain the thin films of TMB•C18H37TCNQ and the orientation of the chromophore plane of TMB keeps nearly unchanged compared with the CT complexe thin films prepared from mixed LB films. The orientation of the hydrocarbon chain of the CT complexes, however, depends on the preparation methods undoubtedly.
Four methods to prepare thin films of charge-transfer complexes have been reviewed and the structural characterization of the related CT films was studied. In the LB films of the complex of N,N,N’,N’-tetramethylbenzidine (N-TMB) and 2-octadecyl-7,7,8,8- tetracyanoquinodimethane (C18H37TCNQ), the chromophore planes for both C18H37TCNQ and N-TMB are nearly parallel to the substrate surface while the hydrocarbon chain is considerably tilted with respect to the substrate normal. By dipping the mixed LB films of stearic acid and C18H37TCNQ into a petroleum ether solution of 3,3’,5,5’-tetramethylbenzidine(TMB), the thin films of charge-transfer complex can also be formed. In that case, the chromophore plane of TMB is nearly perpendicular to the substrate surface with its long axis lying on the substrate. If dipping LB films of pure C18H37TCNQ into a petroleum ether solution of TMB, we can also obtain the thin films of TMB•C18H37TCNQ and the orientation of the chromophore plane of TMB keeps nearly unchanged compared with the CT complexe thin films prepared from mixed LB films. The orientation of the hydrocarbon chain of the CT complexes, however, depends on the preparation methods undoubtedly.
