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2007 Volume 23 Issue 8
2007, 23(08):
Abstract:
2007, 23(08): 1141-1144
doi: 10.1016/S1872-1508(07)60058-8
Abstract:
Some molecules can formaggregates in solution that may inhibit several enzymes, known as promiscuous inhibitors. This phenomenon has been found in traditional Chinese medicinal recipes. To study the aggregation, classification model was constructed by the support vector machine (SVM) classifier. The results indicated that this classification model had od stability and od prediction performance. The experimental results had showed that this predicted model had od generalization. The model was also used to predict the molecules in the Chinese herbal drugs database (CHDD) for further research.
Some molecules can formaggregates in solution that may inhibit several enzymes, known as promiscuous inhibitors. This phenomenon has been found in traditional Chinese medicinal recipes. To study the aggregation, classification model was constructed by the support vector machine (SVM) classifier. The results indicated that this classification model had od stability and od prediction performance. The experimental results had showed that this predicted model had od generalization. The model was also used to predict the molecules in the Chinese herbal drugs database (CHDD) for further research.
2007, 23(08): 1145-1150
doi: 10.3866/PKU.WHXB20070802
Abstract:
Applying the atomic characteristic boundary model, the boundary contours of inert atoms were evaluated in uniform strength electric field, whose strength was 5.292×10-5 - 5.292×10-3 a.u.. The calculated results by an ab initio method showed that the boundary of an atom in a uniform electric field was close to elliptical, and the variation of atomic boundary contour was increased with the increase of the electric field strength. In the same electric field, the larger the atomic number was, the bigger the variation of atomic boundary contour was. Further, it was shown that the mean variation rates of the atomic radial sizes of these atoms in the electric field of unit strength had a od linear relationship with the experimental values of atomic polarizability.
Applying the atomic characteristic boundary model, the boundary contours of inert atoms were evaluated in uniform strength electric field, whose strength was 5.292×10-5 - 5.292×10-3 a.u.. The calculated results by an ab initio method showed that the boundary of an atom in a uniform electric field was close to elliptical, and the variation of atomic boundary contour was increased with the increase of the electric field strength. In the same electric field, the larger the atomic number was, the bigger the variation of atomic boundary contour was. Further, it was shown that the mean variation rates of the atomic radial sizes of these atoms in the electric field of unit strength had a od linear relationship with the experimental values of atomic polarizability.
2007, 23(08): 1151-1156
doi: 10.1016/S1872-1508(07)60059-X
Abstract:
An Fe/Cu/K/Al2O3 catalyst for Fischer-Tropsch synthesis (FTS) was prepared by using a combination of co-precipitation and spray-drying method. Thermal gravity (TG), N2 physisorption, X-ray diffraction (XRD), H2 temperature programmed reduction (H2-TPR), CO temperature programmed reduction (CO-TPR), and Mossbauer effect spectroscopy (MES), were used to investigate the effects of different calcination temperatures on the structural properties, reduction, and carburization behaviors of the iron-based catalyst. The results indicated that an increase in calcination temperature facilitated the carbonate decomposition and H2O removal and promoted the reduction of the catalyst. With further increasing the calcination temperature, the BET surface area of the catalyst decreased, and the size of the catalyst crystallite and the average pore diameter increased. Furthermore, high calcination temperature enhanced the metal-support interaction, which weakened the promotional effect of CuO and K2O, and therefore, severely suppresseed the reduction and carburization behaviors of the catalyst.
An Fe/Cu/K/Al2O3 catalyst for Fischer-Tropsch synthesis (FTS) was prepared by using a combination of co-precipitation and spray-drying method. Thermal gravity (TG), N2 physisorption, X-ray diffraction (XRD), H2 temperature programmed reduction (H2-TPR), CO temperature programmed reduction (CO-TPR), and Mossbauer effect spectroscopy (MES), were used to investigate the effects of different calcination temperatures on the structural properties, reduction, and carburization behaviors of the iron-based catalyst. The results indicated that an increase in calcination temperature facilitated the carbonate decomposition and H2O removal and promoted the reduction of the catalyst. With further increasing the calcination temperature, the BET surface area of the catalyst decreased, and the size of the catalyst crystallite and the average pore diameter increased. Furthermore, high calcination temperature enhanced the metal-support interaction, which weakened the promotional effect of CuO and K2O, and therefore, severely suppresseed the reduction and carburization behaviors of the catalyst.
2007, 23(08): 1157-1162
doi: 10.1016/S1872-1508(07)60060-6
Abstract:
To improve the production efficiency of hydrogen peroxide in Electron-Fenton system, multi-walled carbon nanotube (MWNT) electrode was prepared. Compared with graphite/gas diffusion cathode (GDC) electrode, the MWNT electrode showed higher hydrogen peroxide production efficiency. The Fe-modified MWNT (Fe-MWNT) electrode was prepared using the electro chemical deposition method. The as prepared Fe-MWNT electrode showed higher hydrogen peroxide production efficiency, and the average current efficiency increased by 8%after Fe modification in comparison with the unmodified MWNT. The average current efficiency of the Fe-MWNT electrode was close to that of the GDCelectrode. The Fe-MWNT electrode is a novel promising cathode material for application in the Electron-Fenton system.
To improve the production efficiency of hydrogen peroxide in Electron-Fenton system, multi-walled carbon nanotube (MWNT) electrode was prepared. Compared with graphite/gas diffusion cathode (GDC) electrode, the MWNT electrode showed higher hydrogen peroxide production efficiency. The Fe-modified MWNT (Fe-MWNT) electrode was prepared using the electro chemical deposition method. The as prepared Fe-MWNT electrode showed higher hydrogen peroxide production efficiency, and the average current efficiency increased by 8%after Fe modification in comparison with the unmodified MWNT. The average current efficiency of the Fe-MWNT electrode was close to that of the GDCelectrode. The Fe-MWNT electrode is a novel promising cathode material for application in the Electron-Fenton system.
2007, 23(08): 1163-1167
doi: 10.1016/S1872-1508(07)60061-8
Abstract:
Using the electrochemical cyclic voltammetry, Co-Ni alloy filmwas deposited on single crystal GaAs(001) substrate. With the scanning electron microscopy (SEM) and X-ray fluorescence (XRF), the thickness of the film was about 180 nm and the surface of the alloy was composed of 40 nm-sized Co66Ni34 nanograins. The faced center cubic structure of the alloy was confirmed using X-ray diffraction (XRD). The X-ray magnetic circular dichroism (XMCD) spectra of Co and Niwere obtained from the X-ray absorption spectra (XAS) results using synchrotron radiation circularly polarized soft X-ray. According to the sum rules, the orbital and the spin magnetic moments of Co and Ni were separately obtained. Compared with the pure Co and Ni samples, the orbital and the spin magnetic moments of Co and Ni in the epitaxial Co-Ni alloy showed an increase to some extent.
Using the electrochemical cyclic voltammetry, Co-Ni alloy filmwas deposited on single crystal GaAs(001) substrate. With the scanning electron microscopy (SEM) and X-ray fluorescence (XRF), the thickness of the film was about 180 nm and the surface of the alloy was composed of 40 nm-sized Co66Ni34 nanograins. The faced center cubic structure of the alloy was confirmed using X-ray diffraction (XRD). The X-ray magnetic circular dichroism (XMCD) spectra of Co and Niwere obtained from the X-ray absorption spectra (XAS) results using synchrotron radiation circularly polarized soft X-ray. According to the sum rules, the orbital and the spin magnetic moments of Co and Ni were separately obtained. Compared with the pure Co and Ni samples, the orbital and the spin magnetic moments of Co and Ni in the epitaxial Co-Ni alloy showed an increase to some extent.
2007, 23(08): 1168-1172
doi: 10.1016/S1872-1508(07)60062-X
Abstract:
The wetting behaviors of ethanol/water solutions with different surface tensions were studied on the rough superhydrophobic polytetrafluoroethylene (PTFE) coating. Air fraction was calculated using Cassie equation and the forces were compared. The result indicated that the ethanol/water solutions gradually filled in the multilevel structures of the PTFE coating with the decrease in the surface tension. Only the stripe structure was filled when the surface tension was greater than 28 mN·m-1. When the surface tension was less than 28 mN·m-1, the papillary structure was also filled. Because it has little contribution to the air fraction, the surface could not be wetted when the stripe structure was filled. However, the surface could be wetted by the solutions when the papillary structure, which had a considerable contribution to the air fraction, was filled.
The wetting behaviors of ethanol/water solutions with different surface tensions were studied on the rough superhydrophobic polytetrafluoroethylene (PTFE) coating. Air fraction was calculated using Cassie equation and the forces were compared. The result indicated that the ethanol/water solutions gradually filled in the multilevel structures of the PTFE coating with the decrease in the surface tension. Only the stripe structure was filled when the surface tension was greater than 28 mN·m-1. When the surface tension was less than 28 mN·m-1, the papillary structure was also filled. Because it has little contribution to the air fraction, the surface could not be wetted when the stripe structure was filled. However, the surface could be wetted by the solutions when the papillary structure, which had a considerable contribution to the air fraction, was filled.
2007, 23(08): 1173-1177
doi: 10.3866/PKU.WHXB20070807
Abstract:
A one-step procedure to fabricate anatase crystalline titania hollow spheres was reported. Anatase-crystalline titania hollow spheres were directly fabricated in aqueous solution with peroxo-titanium complex (PTC) as precursor and polystyrene (PS) spheres as template. Compared with the traditionally template method, the surface coating, the template removal and the crystallization of the titania shell were simultaneously finished in a one-step process. Transmission electron microscope (TEM), scanning electron microscopy (SEM), X-ray diffraction (XRD) and thermogravimetric analysis (TGA) were used to characterize the as-prepared titania hollowspheres. A possible formation mechanism was also discussed.
A one-step procedure to fabricate anatase crystalline titania hollow spheres was reported. Anatase-crystalline titania hollow spheres were directly fabricated in aqueous solution with peroxo-titanium complex (PTC) as precursor and polystyrene (PS) spheres as template. Compared with the traditionally template method, the surface coating, the template removal and the crystallization of the titania shell were simultaneously finished in a one-step process. Transmission electron microscope (TEM), scanning electron microscopy (SEM), X-ray diffraction (XRD) and thermogravimetric analysis (TGA) were used to characterize the as-prepared titania hollowspheres. A possible formation mechanism was also discussed.
2007, 23(08): 1178-1182
doi: 10.3866/PKU.WHXB20070808
Abstract:
A modified electrode was prepared by sequential dropping didodecyldimethylammonium bromide (DDAB) with different concentrations and hemoglobin (Hb) solution on pyrolytic graphite (PG) electrode. The electrochemical property of the modified electrode was studied by cyclic voltammetry and UV spectrum. The data analyzed with Laviron model showed that with increasing the DDAB concentration, the thickness of films increased and the heme was released from hemoglobin, so the electrochemical reaction changed from a double-electron process to a single-electron process.
A modified electrode was prepared by sequential dropping didodecyldimethylammonium bromide (DDAB) with different concentrations and hemoglobin (Hb) solution on pyrolytic graphite (PG) electrode. The electrochemical property of the modified electrode was studied by cyclic voltammetry and UV spectrum. The data analyzed with Laviron model showed that with increasing the DDAB concentration, the thickness of films increased and the heme was released from hemoglobin, so the electrochemical reaction changed from a double-electron process to a single-electron process.
2007, 23(08): 1183-1188
doi: 10.1016/S1872-1508(07)60063-1
Abstract:
The structure of 2-(toluene-4-sulfonylamino)-benzoic acid (I) derived from X-ray diffraction of a single crystal was presented and verified by using FT-IR, NMR, and elemental analyses. The compound was crystallized in the monoclinic space group C2/c. The lattice parameters are, a=2.7320(3) nm, b=0.85441(8) nm, c=1.17607(11) nm, α=90°, β=98.728(3)°, γ=90°, V=2.7135(5) nm3, and Z=8. The unimolecules in compound I are engaged in N—H…O and O—H…O hydrogen bonds leading to centrosymmetric dimers, which are interlocked through two distinctly different types of C—H…Ohydrogen bonds and face-to-face π…π interactions resulting in an intriguing supramolecular structure. The compound I exhibited solvatochromism as evidenced from UV-Vis study in different solvent media. Moreover, fluorescence spectra and thermal analysis (DSC-TGA) indicated that the compound I was a photochromic and heatproof material.
The structure of 2-(toluene-4-sulfonylamino)-benzoic acid (I) derived from X-ray diffraction of a single crystal was presented and verified by using FT-IR, NMR, and elemental analyses. The compound was crystallized in the monoclinic space group C2/c. The lattice parameters are, a=2.7320(3) nm, b=0.85441(8) nm, c=1.17607(11) nm, α=90°, β=98.728(3)°, γ=90°, V=2.7135(5) nm3, and Z=8. The unimolecules in compound I are engaged in N—H…O and O—H…O hydrogen bonds leading to centrosymmetric dimers, which are interlocked through two distinctly different types of C—H…Ohydrogen bonds and face-to-face π…π interactions resulting in an intriguing supramolecular structure. The compound I exhibited solvatochromism as evidenced from UV-Vis study in different solvent media. Moreover, fluorescence spectra and thermal analysis (DSC-TGA) indicated that the compound I was a photochromic and heatproof material.
2007, 23(08): 1189-1194
doi: 10.3866/PKU.WHXB20070810
Abstract:
A series of WO3/SBA-16 samples with different W contents were synthesized under hydrothermal conditions using tetraethyl orthosilicate (TEOS) as silica source, ammonium paratungstate as tungsten source, and the mixture of F127 (EO106PO70EP106) and P123 (EO20PO70EP20) as template in strong acidic medium. The corresponding WxC/SBA-16 (x=1, 2) catalysts were prepared by the temperature-programmed carburization (TPC) method using CH4/H2 mixture gases (V(CH4)/V(H2)=1/4) from their oxide precursors. The structures of the samples were characterized by XRD, N2 adsorption/desorption isotherms, TEM, and FTIR. The catalytic performance of the WxC/SBA-16 (x=1, 2) catalysts for the hydrodesulfurization (HDS) of thiophene was evaluated in a continuous-flow fixed-bed quartz reactor. The results indicated that all samples maintained well cage-like structure of SBA-16 mesoporous molecular sieve with a cubic symmetry. In the tungsten carbide catalysts, the tungsten carbide was theW2Cphase when n(Si)/n(W)was from 30 to 10. However, the tungsten carbides were a mixture of W2C and WC phases when n(Si)/n(W) was 7.5. The tungsten carbide catalysts exhibited od catalytic activity for HDS of thiophene.
A series of WO3/SBA-16 samples with different W contents were synthesized under hydrothermal conditions using tetraethyl orthosilicate (TEOS) as silica source, ammonium paratungstate as tungsten source, and the mixture of F127 (EO106PO70EP106) and P123 (EO20PO70EP20) as template in strong acidic medium. The corresponding WxC/SBA-16 (x=1, 2) catalysts were prepared by the temperature-programmed carburization (TPC) method using CH4/H2 mixture gases (V(CH4)/V(H2)=1/4) from their oxide precursors. The structures of the samples were characterized by XRD, N2 adsorption/desorption isotherms, TEM, and FTIR. The catalytic performance of the WxC/SBA-16 (x=1, 2) catalysts for the hydrodesulfurization (HDS) of thiophene was evaluated in a continuous-flow fixed-bed quartz reactor. The results indicated that all samples maintained well cage-like structure of SBA-16 mesoporous molecular sieve with a cubic symmetry. In the tungsten carbide catalysts, the tungsten carbide was theW2Cphase when n(Si)/n(W)was from 30 to 10. However, the tungsten carbides were a mixture of W2C and WC phases when n(Si)/n(W) was 7.5. The tungsten carbide catalysts exhibited od catalytic activity for HDS of thiophene.
2007, 23(08): 1195-1200
doi: 10.3866/PKU.WHXB20070811
Abstract:
A two-sheets model of layered double hydroxides (LDHs) was proposed. The structure parameters and energy of LDHs were calculated using density functional theory at the B3LYP/6-31G(d)// B3LYP/3-21Glevel . Distribution of guest anion and water in the interlayer and the supra-molecular interaction between the host layer and guest had been investigated. The results showed that the optimized guest anion and water paralleled to the host layer. The frontier orbital of the host layer interacted with that of the guest anion, and the electron was transferred from HOMO of CO2-3 to LUMO of the host layer. Moreover, LDHs-CO3 was more stable than LDHs-F and LDHs-Cl, calculating results remained consistent with the ion exchange ability reported. In the process of hydration of LDHs-CO3, hydrogen-bonding was superior to electrostatic interaction, and layer-water type hydrogen-bonding was stronger than anion-water type hydrogen-bonding between H2O and the rest of the structure. Moreover, the calculated hydration energy indicated that the hydration of LDHs-CO3 could achieve a definite saturation state.
A two-sheets model of layered double hydroxides (LDHs) was proposed. The structure parameters and energy of LDHs were calculated using density functional theory at the B3LYP/6-31G(d)// B3LYP/3-21Glevel . Distribution of guest anion and water in the interlayer and the supra-molecular interaction between the host layer and guest had been investigated. The results showed that the optimized guest anion and water paralleled to the host layer. The frontier orbital of the host layer interacted with that of the guest anion, and the electron was transferred from HOMO of CO2-3 to LUMO of the host layer. Moreover, LDHs-CO3 was more stable than LDHs-F and LDHs-Cl, calculating results remained consistent with the ion exchange ability reported. In the process of hydration of LDHs-CO3, hydrogen-bonding was superior to electrostatic interaction, and layer-water type hydrogen-bonding was stronger than anion-water type hydrogen-bonding between H2O and the rest of the structure. Moreover, the calculated hydration energy indicated that the hydration of LDHs-CO3 could achieve a definite saturation state.
2007, 23(08): 1201-1206
doi: 10.3866/PKU.WHXB20070812
Abstract:
The electrochemical quartz crystal microbalance (EQCM) technique was employed to monitor in situ the adsorption of glucose oxidase ( D) onto bare Au, Au-electroplated, and carbon nanotubes(CNTs)-modified Au electrodes. The enzymatic specific activities (ESAi) for D adsorbed on various surfaces were measured from the mass of adsorbed D obtained via EQCM characterization and the charge for oxidation of enzymatically generated H2O2. The results showed that D could adsorb on the investigated surfaces with different adsorption amounts, and the adsorbed D was enzymatically active to some degree; the modification of CNTs increased the adsorption amount of D and the response current to glucose, but the ESAi decreased with the increase of the amount of modified CNTs; the Au electroplating on Au electrode also increased the response current to glucose, but the ESAi changed little after the electroplating.
The electrochemical quartz crystal microbalance (EQCM) technique was employed to monitor in situ the adsorption of glucose oxidase ( D) onto bare Au, Au-electroplated, and carbon nanotubes(CNTs)-modified Au electrodes. The enzymatic specific activities (ESAi) for D adsorbed on various surfaces were measured from the mass of adsorbed D obtained via EQCM characterization and the charge for oxidation of enzymatically generated H2O2. The results showed that D could adsorb on the investigated surfaces with different adsorption amounts, and the adsorbed D was enzymatically active to some degree; the modification of CNTs increased the adsorption amount of D and the response current to glucose, but the ESAi decreased with the increase of the amount of modified CNTs; the Au electroplating on Au electrode also increased the response current to glucose, but the ESAi changed little after the electroplating.
2007, 23(08): 1207-1212
doi: 10.3866/PKU.WHXB20070813
Abstract:
The nanoparticles of ld cores adsorbing asymmetric thioether chains on their surfaces were studied by molecular dynamics simulations. By analyzing correlations of the chains and phenyl rings in the nanoparticles under different order and distance parameters, the most reasonable correlation criterion was finally put forward. The changes of some structural properties such as radial distribution functions of the ld atoms, the sizes of the ld cores as well as the correlations between the chains and/or phenyl rings with the temperatures were investigated for four systems. Melting points of the ld cores were obtained according to the obvious changes or jumps of these properties, and the results were in od accord with each other. Higher melting points indicate that the passirated Au-containing nanoparticles have higher thermal stabilities than unpacked ld clusters. However, the correlations would reduce to a low degree when the temperature is too high, and this would decrease the practicability of using these nanoparticles as nano-electronic devices.
The nanoparticles of ld cores adsorbing asymmetric thioether chains on their surfaces were studied by molecular dynamics simulations. By analyzing correlations of the chains and phenyl rings in the nanoparticles under different order and distance parameters, the most reasonable correlation criterion was finally put forward. The changes of some structural properties such as radial distribution functions of the ld atoms, the sizes of the ld cores as well as the correlations between the chains and/or phenyl rings with the temperatures were investigated for four systems. Melting points of the ld cores were obtained according to the obvious changes or jumps of these properties, and the results were in od accord with each other. Higher melting points indicate that the passirated Au-containing nanoparticles have higher thermal stabilities than unpacked ld clusters. However, the correlations would reduce to a low degree when the temperature is too high, and this would decrease the practicability of using these nanoparticles as nano-electronic devices.
2007, 23(08): 1213-1218
doi: 10.3866/PKU.WHXB20070814
Abstract:
The effect of fluoride ion on the photocatalytic degradation of sulforhodamine B (SRB) on P25 and TiO2/bentonite under UV light irradiation was studied. The results of UV-Vis spectra detection showed that lower pH value lead to higher photodegradation rate in the absense of fluoride ion. And if pH value is fixed, the more the fluoride ion concentration, the faster the reaction rate will be. On TiO2/bentonite catalyst, when fluoride ion concentration reaches a definite value, its reaction rate will not change. The effect of fluoride ion on the production of H2O2 on P25 is different fromthat on TiO2/bentonite. Superoxide radical and hydroxyl radical were detected by electron paramagnetic resonance (EPR) technique. The effects of fluoride ion on these two systems are different. These phenomena may be caused by the special structures of TiO2/bentonite, which is a pillared structure with a large BET surface area and a particle size of about 57.9 nm by XRD and TEM. TiO2/bentonite catalyst was used for 11 cycles continuously, and its photocatalytic reactivity was stable. This phenomenon shows that TiO2/bentonite catalysts are easier to be separated from a dispersion systemand their stability is od. It is a promising catalyst.
The effect of fluoride ion on the photocatalytic degradation of sulforhodamine B (SRB) on P25 and TiO2/bentonite under UV light irradiation was studied. The results of UV-Vis spectra detection showed that lower pH value lead to higher photodegradation rate in the absense of fluoride ion. And if pH value is fixed, the more the fluoride ion concentration, the faster the reaction rate will be. On TiO2/bentonite catalyst, when fluoride ion concentration reaches a definite value, its reaction rate will not change. The effect of fluoride ion on the production of H2O2 on P25 is different fromthat on TiO2/bentonite. Superoxide radical and hydroxyl radical were detected by electron paramagnetic resonance (EPR) technique. The effects of fluoride ion on these two systems are different. These phenomena may be caused by the special structures of TiO2/bentonite, which is a pillared structure with a large BET surface area and a particle size of about 57.9 nm by XRD and TEM. TiO2/bentonite catalyst was used for 11 cycles continuously, and its photocatalytic reactivity was stable. This phenomenon shows that TiO2/bentonite catalysts are easier to be separated from a dispersion systemand their stability is od. It is a promising catalyst.
2007, 23(08): 1219-1223
doi: 10.3866/PKU.WHXB20070815
Abstract:
Transparent pure-silica zeolite (PSZ) films were synthesized on silicon wafers through hydrothermal reaction, in which tetraethyl orthosilicate (TEOS) was used as silica source, tetrapropyl ammonium hydroxide (TPAOH) as template and alkaline source. An ultraviolet treatment was subsequently applied to remove the organic templates within the pores/channels of zeolite films. The thin films were characterized by using FTIR, XRD, and SEM techniques before and after the ultraviolet treatment. FTIR results showed that the organic templates were effectively removed via ultraviolet treatment, which was the same as the results from the calcinations treatment. In comparison with the calcined films, XRD and SEMresults indicated that the crystallinity and the surface as well as the thickness of the films had no significant changes after ultraviolet treatment. Dielectric constant (ε) values of the thin films were measured by means of impedance analyzer. Elastic modulus and hardness of the thin films were measured by the nano-indentation technique. All results showed that the films after ultraviolet treatment had a lower ε value and higher mechanical strength. Therefore, it could be concluded that ultraviolet treatment was a faster, more energy-conservative method to remove template fromzeolite films, in comparison with conventional calcination.
Transparent pure-silica zeolite (PSZ) films were synthesized on silicon wafers through hydrothermal reaction, in which tetraethyl orthosilicate (TEOS) was used as silica source, tetrapropyl ammonium hydroxide (TPAOH) as template and alkaline source. An ultraviolet treatment was subsequently applied to remove the organic templates within the pores/channels of zeolite films. The thin films were characterized by using FTIR, XRD, and SEM techniques before and after the ultraviolet treatment. FTIR results showed that the organic templates were effectively removed via ultraviolet treatment, which was the same as the results from the calcinations treatment. In comparison with the calcined films, XRD and SEMresults indicated that the crystallinity and the surface as well as the thickness of the films had no significant changes after ultraviolet treatment. Dielectric constant (ε) values of the thin films were measured by means of impedance analyzer. Elastic modulus and hardness of the thin films were measured by the nano-indentation technique. All results showed that the films after ultraviolet treatment had a lower ε value and higher mechanical strength. Therefore, it could be concluded that ultraviolet treatment was a faster, more energy-conservative method to remove template fromzeolite films, in comparison with conventional calcination.
2007, 23(08): 1224-1228
doi: 10.3866/PKU.WHXB20070816
Abstract:
The MWCNT (multi-walled carbon nanotube) electrocatalysts with different Pd/Ni atomic ratios were prepared by microwave reduction method. XRD, TEM, and EDS measurements were used to characterize the composition, particle size, and crystallinity of the catalysts. It showed that the Pd-Ni nanoparticles supported on MWCNTs were small and well dispersed on the surface of MWCNTs. The electrocatalytic oxidation of ethylene glycol (EG) was studied by cyclic voltammetry (CV), linear sweep voltammetry (LSV), chronoamperometry (CA) and electrochemical impendance spectroscopy (EIS). It was found that the performance of ethylene glycol electro-oxidation on Pd-Ni/MWCNT electrocatalysts with a Pd/Ni atomic ratio of 3:1 was the best.
The MWCNT (multi-walled carbon nanotube) electrocatalysts with different Pd/Ni atomic ratios were prepared by microwave reduction method. XRD, TEM, and EDS measurements were used to characterize the composition, particle size, and crystallinity of the catalysts. It showed that the Pd-Ni nanoparticles supported on MWCNTs were small and well dispersed on the surface of MWCNTs. The electrocatalytic oxidation of ethylene glycol (EG) was studied by cyclic voltammetry (CV), linear sweep voltammetry (LSV), chronoamperometry (CA) and electrochemical impendance spectroscopy (EIS). It was found that the performance of ethylene glycol electro-oxidation on Pd-Ni/MWCNT electrocatalysts with a Pd/Ni atomic ratio of 3:1 was the best.
2007, 23(08): 1229-1234
doi: 10.3866/PKU.WHXB20070817
Abstract:
The isomerization reactions of IClO2 were studied by density functional theory. Seven isomers were optimized and two newisomers (OIClOand IClOO) were gained, IRC calculations were also been processed to validate the connection relationship of the isomers. From the view of topological analysis of the electronic density, the topological characters of the major critical points along the reaction pathway were analyzed, the changing rules of the chemical bonds were discussed, and the energy transition states (ETS) and structure transition states (STS) were found.
The isomerization reactions of IClO2 were studied by density functional theory. Seven isomers were optimized and two newisomers (OIClOand IClOO) were gained, IRC calculations were also been processed to validate the connection relationship of the isomers. From the view of topological analysis of the electronic density, the topological characters of the major critical points along the reaction pathway were analyzed, the changing rules of the chemical bonds were discussed, and the energy transition states (ETS) and structure transition states (STS) were found.
2007, 23(08): 1235-1240
doi: 10.3866/PKU.WHXB20070818
Abstract:
A novel inorganic-organic composite membrane based on sulfonated poly(phthalazinone ether keton) (SPPEK) with embedded phosphotungstic acid (PWA) was prepared. IR spectra results indicated that both the bridging oxygen and the terminal oxygen of PWA interacted with SPPEK. PWAwas well dispersed in the membranes with 20% and 40% PWA in SPPEK of 58% sulfonation degree as shown in SEM pictures. But conglomeration was found in the SEM picture of composite membrane with 60% PWA. After treated in water for four days, less than 10% PWA was extracted from the composite membranes. With the increment of PWA content, the conductivity, water content, and methanol permeability of the PWA/SPPEK composite membranes were all increased. The composite membranes with PWA content higher than 40% and SPPEK of 58% sulfonation degree have conductivity similar or superior to that of Nafion115 membrane at temperature higher than 100 ℃. Methanol permeability of the PWA/SPPEK composite membranes was lower than that of Nafion115 membrane except the composite membrane with 60%PWA in SPPEK of 58%sulfonation degree.
A novel inorganic-organic composite membrane based on sulfonated poly(phthalazinone ether keton) (SPPEK) with embedded phosphotungstic acid (PWA) was prepared. IR spectra results indicated that both the bridging oxygen and the terminal oxygen of PWA interacted with SPPEK. PWAwas well dispersed in the membranes with 20% and 40% PWA in SPPEK of 58% sulfonation degree as shown in SEM pictures. But conglomeration was found in the SEM picture of composite membrane with 60% PWA. After treated in water for four days, less than 10% PWA was extracted from the composite membranes. With the increment of PWA content, the conductivity, water content, and methanol permeability of the PWA/SPPEK composite membranes were all increased. The composite membranes with PWA content higher than 40% and SPPEK of 58% sulfonation degree have conductivity similar or superior to that of Nafion115 membrane at temperature higher than 100 ℃. Methanol permeability of the PWA/SPPEK composite membranes was lower than that of Nafion115 membrane except the composite membrane with 60%PWA in SPPEK of 58%sulfonation degree.
2007, 23(08): 1241-1246
doi: 10.3866/PKU.WHXB20070819
Abstract:
Colloidal aggregation within the context of long range van der Waals forces was studied by computer simulations. The motion of colloidal particles or clusters was guided by the long range van der Waals forces. Compared to the diffusion limited cluster aggregation (DLCA), which takes no account of the guiding effect, the directionalism of van der Waals forces not only accelerates the aggregation velocity but also results in morphologies of clusters with higher density and higher fractal dimensions. The directionalism arising from long range van der Waals forces was very sensitive to the initial concentration of particles. Whether on the morphology or on the aggregating velocity, the directionalism was distinct only at low initial concentration of particles. The possible reason was that, at a high particle concentration condition, both a short average random range and the steric effect of particles may screen the guiding effect.
Colloidal aggregation within the context of long range van der Waals forces was studied by computer simulations. The motion of colloidal particles or clusters was guided by the long range van der Waals forces. Compared to the diffusion limited cluster aggregation (DLCA), which takes no account of the guiding effect, the directionalism of van der Waals forces not only accelerates the aggregation velocity but also results in morphologies of clusters with higher density and higher fractal dimensions. The directionalism arising from long range van der Waals forces was very sensitive to the initial concentration of particles. Whether on the morphology or on the aggregating velocity, the directionalism was distinct only at low initial concentration of particles. The possible reason was that, at a high particle concentration condition, both a short average random range and the steric effect of particles may screen the guiding effect.
2007, 23(08): 1247-1251
doi: 10.3866/PKU.WHXB20070820
Abstract:
Direct electrochemistry of hemoglobin (Hb) was investigated on a roomtemperature ionic liquid 1-butyl-3-methylimidazolium hexafluorophosphate ([BMIM]PF6) modified carbon paste electrode (CILE). The CILE was characterized by scanning electron microscopy (SEM) and electrochemical impedance spectroscopy (EIS). Hb was immobilized on the CILE with a chitosan-bentonite composite film and a pair of well-defined, quasi-reversible cyclic voltammetric redox peaks was obtained, which was characteristics of Hb Fe(III)/Fe(II) redox couples. The formal potential (E0’), the electron transfer number (n), and transfer coefficient (α) were calculated as -0.352 V (vs SCE), 0.885, and 0.578, respectively, which indicated that one electron was transferred between heme group of Hb and the electrode. The average apparent heterogeneous electron transfer rate constant (ks) obtained for Hb was 0.149 s-1.
Direct electrochemistry of hemoglobin (Hb) was investigated on a roomtemperature ionic liquid 1-butyl-3-methylimidazolium hexafluorophosphate ([BMIM]PF6) modified carbon paste electrode (CILE). The CILE was characterized by scanning electron microscopy (SEM) and electrochemical impedance spectroscopy (EIS). Hb was immobilized on the CILE with a chitosan-bentonite composite film and a pair of well-defined, quasi-reversible cyclic voltammetric redox peaks was obtained, which was characteristics of Hb Fe(III)/Fe(II) redox couples. The formal potential (E0’), the electron transfer number (n), and transfer coefficient (α) were calculated as -0.352 V (vs SCE), 0.885, and 0.578, respectively, which indicated that one electron was transferred between heme group of Hb and the electrode. The average apparent heterogeneous electron transfer rate constant (ks) obtained for Hb was 0.149 s-1.
2007, 23(08): 1252-1256
doi: 10.3866/PKU.WHXB20070821
Abstract:
Hydrogenated amorphous silicon films were grown by radio frequency plasma enhanced chemical vapor deposition (RF-PECVD) and the substrate temperature of samples changed in the range of 175-275 ℃. Fourier-transform infrared spectrometer (FTIR) was used to characterize the infrared spectral feature of films deposited on KBr substrate. The hydrogen content of films was influenced by substrate temperature according to the FTIR spectra and theoretic analysis. The refractive index (n), extinction coefficient (k), thickness of films and optical band gap (Eg(FB)) were obtained through Forouhi Bloomer (FB) model in spectrum ellipsomet (SE). Appearance of fracture was analyzed by scanning electron microscopy (SEM) to make sure the result of filmthickness. The optical band gap (Eg(Tauc)) and cutoff wavelength were also deduced by Tauc formula, and the difference between Eg(FB) and Eg(Tauc) was within 0.015 eV.
Hydrogenated amorphous silicon films were grown by radio frequency plasma enhanced chemical vapor deposition (RF-PECVD) and the substrate temperature of samples changed in the range of 175-275 ℃. Fourier-transform infrared spectrometer (FTIR) was used to characterize the infrared spectral feature of films deposited on KBr substrate. The hydrogen content of films was influenced by substrate temperature according to the FTIR spectra and theoretic analysis. The refractive index (n), extinction coefficient (k), thickness of films and optical band gap (Eg(FB)) were obtained through Forouhi Bloomer (FB) model in spectrum ellipsomet (SE). Appearance of fracture was analyzed by scanning electron microscopy (SEM) to make sure the result of filmthickness. The optical band gap (Eg(Tauc)) and cutoff wavelength were also deduced by Tauc formula, and the difference between Eg(FB) and Eg(Tauc) was within 0.015 eV.
2007, 23(08): 1257-1259
doi: 10.3866/PKU.WHXB20070822
Abstract:
Cold crystallization process of N-(1-naphthyl) succinimide below glass transition temperature was monitored by differential scanning calorimetry (DSC) and X-ray diffraction (XRD). The results showed that the kinetic curve of cold crystallization was completely different from that of melt crystallization, exhibiting "fast-slow-fast" three increasing stages. This result could be explained in terms of low-density-interface nucleation and volume-contraction effect.
Cold crystallization process of N-(1-naphthyl) succinimide below glass transition temperature was monitored by differential scanning calorimetry (DSC) and X-ray diffraction (XRD). The results showed that the kinetic curve of cold crystallization was completely different from that of melt crystallization, exhibiting "fast-slow-fast" three increasing stages. This result could be explained in terms of low-density-interface nucleation and volume-contraction effect.
2007, 23(08): 1260-1264
doi: 10.3866/PKU.WHXB20070823
Abstract:
Sodiumbenzenesulfonate (SNzS) and sodiumnaphthalenesulfonate (SNphS) added in the solution strongly associated with quaternary ammonium gemini surfactants (C12-s-C12·2Br), which increased the hydrophobicity of C12-s-C12·2Br molecule and obviously enhanced their adsorption at the air/water interface and aggregation in the solution. This resulted in great increase in the efficiency and the effectiveness in surface tension reduction, and the formation of small aggregates in the solution at very low concentration of surfactant. Thus, the cmc obtained by surface tension method was only of apparent significance and it reflected the critical concentration when the surfactant reaching saturated adsorption at the air/water interface. Compared with SNzS, SNphS promoted more effectively both adsorption and aggregation of C12-s-C12·2Br due to its higher hydrophobicity.
Sodiumbenzenesulfonate (SNzS) and sodiumnaphthalenesulfonate (SNphS) added in the solution strongly associated with quaternary ammonium gemini surfactants (C12-s-C12·2Br), which increased the hydrophobicity of C12-s-C12·2Br molecule and obviously enhanced their adsorption at the air/water interface and aggregation in the solution. This resulted in great increase in the efficiency and the effectiveness in surface tension reduction, and the formation of small aggregates in the solution at very low concentration of surfactant. Thus, the cmc obtained by surface tension method was only of apparent significance and it reflected the critical concentration when the surfactant reaching saturated adsorption at the air/water interface. Compared with SNzS, SNphS promoted more effectively both adsorption and aggregation of C12-s-C12·2Br due to its higher hydrophobicity.
2007, 23(08): 1265-1268
doi: 10.3866/PKU.WHXB20070824
Abstract:
Eutectic mixed lithium salts were studied with thermal analysis method. The cooling curves and T-x phase diagrams of lithium salts were plotted in this article. The result showed that these binary systems were simple eutectic systems and had the lowest melt points. The lowest melt points of the eutectic mixed LiOH-LiNO3, LiOH-LiCl, LiOH-Li2CO3, and LiNO3-LiCl were 175.7, 294.5, 418.2, and 221.6 ℃, respectively. Eutectic mixture of LiNO3-LiOH was used as lithium salt with different precursors to prepare cathode materials LiNiO2, LiNi0.8Co0.2O2, and LiNi1/3Co1/3Mn1/3O2 for lithium ion battery. XRD results showed that the prepared cathode materials possessed an ordered NaFeO2 layer structure. The intensity ratios of XRD lines I(003)/I(104) of the prepared cathode materials were all greater than 2.0, which means the samples had a better-developed layer structure. Electrochemical property tests testified that for charge-discharge current density of 0.1C and voltage of 2.7-4.3 V(vs Li/Li+), the initial charge specific capacities of prepared LiNiO2, LiNi0.8Co0.2O2, and LiNi1/3Co1/3Mn1/3O2 were 168.0, 225.4, and 194.0 mAh·g-1, and the discharge specific capacities were 138.4, 165.8, and 157.7 mAh·g-1, respectively. Therefore it was a novel and efficient approach that eutectic mixed salts were used to prepare the cathode materials for lithiumion battery.
Eutectic mixed lithium salts were studied with thermal analysis method. The cooling curves and T-x phase diagrams of lithium salts were plotted in this article. The result showed that these binary systems were simple eutectic systems and had the lowest melt points. The lowest melt points of the eutectic mixed LiOH-LiNO3, LiOH-LiCl, LiOH-Li2CO3, and LiNO3-LiCl were 175.7, 294.5, 418.2, and 221.6 ℃, respectively. Eutectic mixture of LiNO3-LiOH was used as lithium salt with different precursors to prepare cathode materials LiNiO2, LiNi0.8Co0.2O2, and LiNi1/3Co1/3Mn1/3O2 for lithium ion battery. XRD results showed that the prepared cathode materials possessed an ordered NaFeO2 layer structure. The intensity ratios of XRD lines I(003)/I(104) of the prepared cathode materials were all greater than 2.0, which means the samples had a better-developed layer structure. Electrochemical property tests testified that for charge-discharge current density of 0.1C and voltage of 2.7-4.3 V(vs Li/Li+), the initial charge specific capacities of prepared LiNiO2, LiNi0.8Co0.2O2, and LiNi1/3Co1/3Mn1/3O2 were 168.0, 225.4, and 194.0 mAh·g-1, and the discharge specific capacities were 138.4, 165.8, and 157.7 mAh·g-1, respectively. Therefore it was a novel and efficient approach that eutectic mixed salts were used to prepare the cathode materials for lithiumion battery.
2007, 23(08): 1269-1274
doi: 10.3866/PKU.WHXB20070825
Abstract:
4,4’-isopropylidenediphenol (BPA) was used as a template to control the surface morphology of TiO2 films. A solution was produced by evenly stirring the mixture of the BPA ethanol solution and the TiO2 sol containing anatase grains. The films was prepared from resultant solution by a dip-coating technique, and then the BPA was preferentially extracted by anhydrous ethanol. So the anatase TiO2 films were obtained at low temperature, and the control of the surface morphology of the films was also achieved. Scanning electron microscopy (SEM) was adopted to analyze the influence of the dosage of TiO2 sol, BPA, and the anhydrous ethanol on the morphology of the films, and the control mechanism was also discussed. The results showed that the composition of the solution could affect the move and the aggregation of particles in the drying process of wet films, and thus change the distribution of TiO2 and BPA on the surface of the films, and ultimately influence the surface structure of TiO2 films. With the decrease of BPA concentration, the effect region of BPA was changed from the inside region of the film to the surface region of the film. Low concentration of TiO2 colloidal particle and high content of ethanol were propitious to form rough morphology or porous structure.
4,4’-isopropylidenediphenol (BPA) was used as a template to control the surface morphology of TiO2 films. A solution was produced by evenly stirring the mixture of the BPA ethanol solution and the TiO2 sol containing anatase grains. The films was prepared from resultant solution by a dip-coating technique, and then the BPA was preferentially extracted by anhydrous ethanol. So the anatase TiO2 films were obtained at low temperature, and the control of the surface morphology of the films was also achieved. Scanning electron microscopy (SEM) was adopted to analyze the influence of the dosage of TiO2 sol, BPA, and the anhydrous ethanol on the morphology of the films, and the control mechanism was also discussed. The results showed that the composition of the solution could affect the move and the aggregation of particles in the drying process of wet films, and thus change the distribution of TiO2 and BPA on the surface of the films, and ultimately influence the surface structure of TiO2 films. With the decrease of BPA concentration, the effect region of BPA was changed from the inside region of the film to the surface region of the film. Low concentration of TiO2 colloidal particle and high content of ethanol were propitious to form rough morphology or porous structure.
2007, 23(08): 1275-1280
doi: 10.3866/PKU.WHXB20070826
Abstract:
CeO2-based solid solutions (Ce0.7Zr0.3O2-δ, Ce0.7Pr0.3O2-δ, and Ce0.7Gd0.3O2-δ) were prepared using a sol-gel method. Catalytic behaviors for diesel soot combustion over the CeO2-based solid solutions and three typical supports (TiO2, SiO2, and Al2O3) and their KNO3 doped catalysts have been studied. It was found that the CeO2-based solid solution catalysts had nearly the same od catalytic activity as the 30% KNO3 doped TiO2, SiO2, and Al2O3 had. As the formation of the CeO2-based solid solutions can slow down the sintering process and form more active oxygen, which enhanced the reducibility and hence improved the catalytic combustion activity. As the intrinsic high activity of the CeO2-based solid solutions, the addition of the KNO3 did not have obvious effect on them, especially for Ce0.7Zr0.3O2-δ and Ce0.7Pr0.3O2-δ, while for TiO2, SiO2, and Al2O3, the addition of KNO3 could remarkably enhance the combustion activity.
CeO2-based solid solutions (Ce0.7Zr0.3O2-δ, Ce0.7Pr0.3O2-δ, and Ce0.7Gd0.3O2-δ) were prepared using a sol-gel method. Catalytic behaviors for diesel soot combustion over the CeO2-based solid solutions and three typical supports (TiO2, SiO2, and Al2O3) and their KNO3 doped catalysts have been studied. It was found that the CeO2-based solid solution catalysts had nearly the same od catalytic activity as the 30% KNO3 doped TiO2, SiO2, and Al2O3 had. As the formation of the CeO2-based solid solutions can slow down the sintering process and form more active oxygen, which enhanced the reducibility and hence improved the catalytic combustion activity. As the intrinsic high activity of the CeO2-based solid solutions, the addition of the KNO3 did not have obvious effect on them, especially for Ce0.7Zr0.3O2-δ and Ce0.7Pr0.3O2-δ, while for TiO2, SiO2, and Al2O3, the addition of KNO3 could remarkably enhance the combustion activity.
2007, 23(08): 1281-1284
doi: 10.3866/PKU.WHXB20070827
Abstract:
Well-defined CaCO3 hollow spheres were prepared easily in a triblock copolymer P123, poly methacrylic acid (PMAA) and sodiumdodecylsulfate (SDS) ternary-additive system combined by the in situ polymerization of MAA monomers through addition of a certain amount of initiator. The as-prepared products were characterized with scanning electron microscopy and X-ray diffraction. The results suggested that the sizes of the calcite hollow spheres ranged from 0.5 to 2 μm. The wall of the sphere was constituted of many small round particles with the diameter from 25 to 35 nm and the wall thickness from 100 to 300 nm. Moreover, the formation of the hollow spherical structure was interpreted in terms of the core-shell mechanism.
Well-defined CaCO3 hollow spheres were prepared easily in a triblock copolymer P123, poly methacrylic acid (PMAA) and sodiumdodecylsulfate (SDS) ternary-additive system combined by the in situ polymerization of MAA monomers through addition of a certain amount of initiator. The as-prepared products were characterized with scanning electron microscopy and X-ray diffraction. The results suggested that the sizes of the calcite hollow spheres ranged from 0.5 to 2 μm. The wall of the sphere was constituted of many small round particles with the diameter from 25 to 35 nm and the wall thickness from 100 to 300 nm. Moreover, the formation of the hollow spherical structure was interpreted in terms of the core-shell mechanism.
2007, 23(08): 1285-1287
doi: 10.3866/PKU.WHXB20070828
Abstract:
Metastable equilibrium solubilities and densities of the quaternary system of K2B4O7-Na2B4O7-Li2B4O7-H2O at 273 K were studied by isothermal evaporation method. Based on the solubility data, the metastable equilibrium phase diagramof the systemwas plotted, which consists of one invariant point E; three univariant curves E1E, E2E, and E3E, three crystallization fields Na2B4O7·10H2O , K2B4O7·4H2O, and LiBO2·8H2O. Potassium borate (K2B4O7) had the largest solubility in the system.
Metastable equilibrium solubilities and densities of the quaternary system of K2B4O7-Na2B4O7-Li2B4O7-H2O at 273 K were studied by isothermal evaporation method. Based on the solubility data, the metastable equilibrium phase diagramof the systemwas plotted, which consists of one invariant point E; three univariant curves E1E, E2E, and E3E, three crystallization fields Na2B4O7·10H2O , K2B4O7·4H2O, and LiBO2·8H2O. Potassium borate (K2B4O7) had the largest solubility in the system.
2007, 23(08): 1288-1290
doi: 10.3866/PKU.WHXB20070829
Abstract:
Erbiumdoped Y2O3 (Y2O3:Er3+) particles were prepared by microwave method and sol-gel method. Using microwave method the calcining temperature was decreased to 600 ℃. Two upconverting emission bands centered at 550 and 660 nm were presented under 980 nm laser excitation. Samples prepared by microwave method showed a strong red emission and a week green emission, while samples prepared by sol-gel method showed a strong green emission and a week red emission. The results showed that microwave promoted the formation of S6 symmetric structures and the S6 symmetric structures promoted the red emission.
Erbiumdoped Y2O3 (Y2O3:Er3+) particles were prepared by microwave method and sol-gel method. Using microwave method the calcining temperature was decreased to 600 ℃. Two upconverting emission bands centered at 550 and 660 nm were presented under 980 nm laser excitation. Samples prepared by microwave method showed a strong red emission and a week green emission, while samples prepared by sol-gel method showed a strong green emission and a week red emission. The results showed that microwave promoted the formation of S6 symmetric structures and the S6 symmetric structures promoted the red emission.
2007, 23(08): 1291-1295
doi: 10.3866/PKU.WHXB20070830
Abstract:
Influences of cholesterol on N,N-dilauryl chitosan (DLCS) monolayer and corresponding vesicle property were studied. Experimental results indicated that the properties of N,N-dilauryl chitosan monolayer and corresponding vesicle were evidently changed by introducing cholesterol in matrix. Mixed monolayers with lower fraction of cholesterol were less rigid and compressible than pure DLCS monolayer. As the content of cholesterol increasing, however, the rigidity and compressibility of mixed monolayer were increased. In parallel, both the rate of drug-release and the equilibrium drug-release ratio of the vesicles were increased with lower cholesterol content, and they could be decreased with increasing the cholesterol content. The equilibrium drug-release ratio of the vesicle was decreased with increasing the compressibility of corresponding material monolayer, showing a linear relationship. Experimental results provide a possible way for preparing DLCS vesicle with controlled drug-release behavior by adjusting content of cholesterol in vesicle matrix.
Influences of cholesterol on N,N-dilauryl chitosan (DLCS) monolayer and corresponding vesicle property were studied. Experimental results indicated that the properties of N,N-dilauryl chitosan monolayer and corresponding vesicle were evidently changed by introducing cholesterol in matrix. Mixed monolayers with lower fraction of cholesterol were less rigid and compressible than pure DLCS monolayer. As the content of cholesterol increasing, however, the rigidity and compressibility of mixed monolayer were increased. In parallel, both the rate of drug-release and the equilibrium drug-release ratio of the vesicles were increased with lower cholesterol content, and they could be decreased with increasing the cholesterol content. The equilibrium drug-release ratio of the vesicle was decreased with increasing the compressibility of corresponding material monolayer, showing a linear relationship. Experimental results provide a possible way for preparing DLCS vesicle with controlled drug-release behavior by adjusting content of cholesterol in vesicle matrix.
2007, 23(08): 1296-1300
doi: 10.3866/PKU.WHXB20070831
Abstract:
Two kinds of poly(dimethylsiloxane) (PDMS) rough surfaces with different geometries which were square pillars and parallel grating were designed and fabricated by replica molding (REM). Scanning electron microscope (SEM) images showed that the fabricated samples had high fidelity. The contact angles of water droplet on the PDMS square pillars surface and parallel grating surface were (154.6依0.7)° and (160.2依1.9)°, respectively, and the sliding angles were not larger than 6° and 3°, respectively, which attained to the standard of superhydrophobicity. The experimental result of blood platelets adhesion demonstrated that these two superhydrophobic PDMS rough surfaces had better blood compatibility than PDMS planar surface. The crazing and shedding of microstructures in the replica molding were also analyzed and discussed. All results showed that these superhydrophobic materials may be used in industrial and agricultural fields and bioengineering field.
Two kinds of poly(dimethylsiloxane) (PDMS) rough surfaces with different geometries which were square pillars and parallel grating were designed and fabricated by replica molding (REM). Scanning electron microscope (SEM) images showed that the fabricated samples had high fidelity. The contact angles of water droplet on the PDMS square pillars surface and parallel grating surface were (154.6依0.7)° and (160.2依1.9)°, respectively, and the sliding angles were not larger than 6° and 3°, respectively, which attained to the standard of superhydrophobicity. The experimental result of blood platelets adhesion demonstrated that these two superhydrophobic PDMS rough surfaces had better blood compatibility than PDMS planar surface. The crazing and shedding of microstructures in the replica molding were also analyzed and discussed. All results showed that these superhydrophobic materials may be used in industrial and agricultural fields and bioengineering field.
2007, 23(08): 1301-1305
doi: 10.3866/PKU.WHXB20070832
Abstract:
Electrodeposited Sm-Co alloy films, obtained on copper substrate in urea-acetamide-NaBr-KBr melt at 353 K, were prepared. The cyclic voltammetry was used to study the electrochemical processes. Electroreduction of Co (II) to metallic Co was irreversible in one step. On Pt electrode the diffusion coefficient D0 and electron transfer coefficient α of Co(II) in CoCl2 (0.040 mol·L-1)-urea-acetamide-NaBr-KBr were determined. Their values were obtained as follows: α=0.31 and D0=4.78×10-5 cm2·s-1. Sm(III) was not reduced to Sm alone, but it could be inductively codeposited with Co (II). The cathode potential had evident effect on the content of Sm in the Sm-Co alloy films. The content of Sm was analyzed by inductive coupled plasma emission spectrometer (ICPES). The structures phase of the deposits before and after annealing at 923K for 30 s were investigated by XRD, magnetic properties were measured by vibrating sample measurement (VSM), and the microstructure was observed by scanning electron micrographs (SEM). The experimental results revealed that, (1) the prepared samples were amorphous while the annealed those were polycrystalline, and there existed a main hcp phase in annealed polycrystalline samples; (2) the annealing and the samariumcontent had important influence on magnetic properties of SmxCo5 alloy films.
Electrodeposited Sm-Co alloy films, obtained on copper substrate in urea-acetamide-NaBr-KBr melt at 353 K, were prepared. The cyclic voltammetry was used to study the electrochemical processes. Electroreduction of Co (II) to metallic Co was irreversible in one step. On Pt electrode the diffusion coefficient D0 and electron transfer coefficient α of Co(II) in CoCl2 (0.040 mol·L-1)-urea-acetamide-NaBr-KBr were determined. Their values were obtained as follows: α=0.31 and D0=4.78×10-5 cm2·s-1. Sm(III) was not reduced to Sm alone, but it could be inductively codeposited with Co (II). The cathode potential had evident effect on the content of Sm in the Sm-Co alloy films. The content of Sm was analyzed by inductive coupled plasma emission spectrometer (ICPES). The structures phase of the deposits before and after annealing at 923K for 30 s were investigated by XRD, magnetic properties were measured by vibrating sample measurement (VSM), and the microstructure was observed by scanning electron micrographs (SEM). The experimental results revealed that, (1) the prepared samples were amorphous while the annealed those were polycrystalline, and there existed a main hcp phase in annealed polycrystalline samples; (2) the annealing and the samariumcontent had important influence on magnetic properties of SmxCo5 alloy films.
2007, 23(08): 1306-1310
doi: 10.3866/PKU.WHXB20070833
Abstract:
Co/Cumultilayer nanowire arrays embedded in anodic alumina (AAO) template were successfully prepared by dual-bath electrodeposition technique. SEM and TEM indicated that the Co/Cu nanowires were regularly spaced and uniform in shape with lengths of about 20 μm and diameters of 80 nm. The bilayer thicknesses of the two samples were 50 nm and 200 nm respectively. XRD test indicated that the Co and Cu grew in their (hcp) and (fcc) polycrystal structures, respectively. VSM test indicated that nanowire arrays had apparent magnetic anisotropy. The giant magnetoresistance (GMR) ratio of the nanowire arrays with the bilayer thickness of 50 nm was about -75%, whereas the bilayer thickness increased to 200 nm, the nanowire arrays had not GMR effect.
Co/Cumultilayer nanowire arrays embedded in anodic alumina (AAO) template were successfully prepared by dual-bath electrodeposition technique. SEM and TEM indicated that the Co/Cu nanowires were regularly spaced and uniform in shape with lengths of about 20 μm and diameters of 80 nm. The bilayer thicknesses of the two samples were 50 nm and 200 nm respectively. XRD test indicated that the Co and Cu grew in their (hcp) and (fcc) polycrystal structures, respectively. VSM test indicated that nanowire arrays had apparent magnetic anisotropy. The giant magnetoresistance (GMR) ratio of the nanowire arrays with the bilayer thickness of 50 nm was about -75%, whereas the bilayer thickness increased to 200 nm, the nanowire arrays had not GMR effect.
