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1990 Volume 6 Issue 4
1990, 6(04): 385-388
doi: 10.3866/PKU.WHXB19900401
Abstract:
Tight-binding band calculations were performed on Cu_2Bi_2O_8~(6-) and Cu_4O_(12)~(16-) complexes modelling the Bi_2Sr_2CuO_6 sublattice and CuO_2 sheet respectively. We investigate the effect of the oxidation and the planar-oxygen breathing-mode vibration on the d_(x~2-y~2) valence bands and Mulliken charge of Cu and O. The results show that the breathing mode causes the splitting of d_(x~2-y~2) bands at E_f and charge fluctuation between Cu-O complexes, the oxidation strengthenes the charge fluctuation, thereby favoring the formation of pairing.
Tight-binding band calculations were performed on Cu_2Bi_2O_8~(6-) and Cu_4O_(12)~(16-) complexes modelling the Bi_2Sr_2CuO_6 sublattice and CuO_2 sheet respectively. We investigate the effect of the oxidation and the planar-oxygen breathing-mode vibration on the d_(x~2-y~2) valence bands and Mulliken charge of Cu and O. The results show that the breathing mode causes the splitting of d_(x~2-y~2) bands at E_f and charge fluctuation between Cu-O complexes, the oxidation strengthenes the charge fluctuation, thereby favoring the formation of pairing.
1990, 6(04): 389-391
doi: 10.3866/PKU.WHXB19900402
Abstract:
The Ms 80 standard calvet microcalorimeter was used for measuring the thermo-grams of Hela, human breast carcinoma(Bcap-37) and diploid fibroblasts from human fetal lung (2BS) at 37 ℃ under the conditions of normal cell culture and culture in the presence of bioactive materials in Spirulina. There is a difference in the shapes of thermograms beteween tumor cells (Hela, Bcap-37) and normal coll (2BS) under the same condition. The former tended to ascent and the latter was almost parallel to abscissa during the measurements. The cell number was counted and the inhibit rate of growth and the death rate were obtained. The Sp. P was growth inhibitor and lethal to tumo cells, but had no influence on the growth of 2BS at the concentration of 100 μg·ml~(-1).
The Ms 80 standard calvet microcalorimeter was used for measuring the thermo-grams of Hela, human breast carcinoma(Bcap-37) and diploid fibroblasts from human fetal lung (2BS) at 37 ℃ under the conditions of normal cell culture and culture in the presence of bioactive materials in Spirulina. There is a difference in the shapes of thermograms beteween tumor cells (Hela, Bcap-37) and normal coll (2BS) under the same condition. The former tended to ascent and the latter was almost parallel to abscissa during the measurements. The cell number was counted and the inhibit rate of growth and the death rate were obtained. The Sp. P was growth inhibitor and lethal to tumo cells, but had no influence on the growth of 2BS at the concentration of 100 μg·ml~(-1).
1990, 6(04): 392-398
doi: 10.3866/PKU.WHXB19900403
Abstract:
In this paper, surface state and properties of MoO_3 supported onto the surface of TiO_2/γ-Al_2O_3 carrier (i. e. TiO_2 supported onto the γ-Al_2O_3) are reported. Carrier we selected is S-20 of which TiO_2 loading is 0.20 g/g γ-Al_2O_3. The physico-chemical properties of the carrier was described in reference[6]. MoO_3 supported on carrier was prepared in two ways: one is general impregnation method and another is that the MoO_3 and S-20 powders were mixed throughly and then the mixture was calcined at 450 ℃ for 24 hrs. The surface state of MoO_3/TiO_2/γ-Al_2O_3 was characterized by using of it are quite different from MoO_3 supported on TiO_2 or γ-Al_2O_3. This results are of benefit to developing new catalysts.
The experimental results of XRD quantitative analysis and XPS intensity ratio and LRS quantitative analysis show that the utmost monolayer dispersion capacity of MoO_3 supported on TiO_2 or γ-Al_2O_3 meets the calculated value very well. It illustrates that the new carrier we made has an ability to increasing the MoO_3 dispersion capacity to 23% more.
The results of LRS and ammonia leaching and XRD..
In this paper, surface state and properties of MoO_3 supported onto the surface of TiO_2/γ-Al_2O_3 carrier (i. e. TiO_2 supported onto the γ-Al_2O_3) are reported. Carrier we selected is S-20 of which TiO_2 loading is 0.20 g/g γ-Al_2O_3. The physico-chemical properties of the carrier was described in reference[6]. MoO_3 supported on carrier was prepared in two ways: one is general impregnation method and another is that the MoO_3 and S-20 powders were mixed throughly and then the mixture was calcined at 450 ℃ for 24 hrs. The surface state of MoO_3/TiO_2/γ-Al_2O_3 was characterized by using of it are quite different from MoO_3 supported on TiO_2 or γ-Al_2O_3. This results are of benefit to developing new catalysts.
The experimental results of XRD quantitative analysis and XPS intensity ratio and LRS quantitative analysis show that the utmost monolayer dispersion capacity of MoO_3 supported on TiO_2 or γ-Al_2O_3 meets the calculated value very well. It illustrates that the new carrier we made has an ability to increasing the MoO_3 dispersion capacity to 23% more.
The results of LRS and ammonia leaching and XRD..
An an initio Study on the Molecular Structures and Stabilities of CF3NO,CF2ClNO3,CFCl2NO3 and CCl3NO
1990, 6(04): 399-402
doi: 10.3866/PKU.WHXB19900404
Abstract:
The molecular structures and stabilities of CF_3NO(1), CF_2ClNO(2) CFCl_2NO(3) and CCl_3NO(4) have been studied by ab initio method at STO-3G level. The results indicated that eclipsed geometry is stabler in the molecules, in 2 or 3, the geometry which Cl is in same side with O is stabler than the geometry which F is in same side with O and the stabilities of the molecules decrease from 1 to 4, Ab initio results are in agreement with experimental results.
The molecular structures and stabilities of CF_3NO(1), CF_2ClNO(2) CFCl_2NO(3) and CCl_3NO(4) have been studied by ab initio method at STO-3G level. The results indicated that eclipsed geometry is stabler in the molecules, in 2 or 3, the geometry which Cl is in same side with O is stabler than the geometry which F is in same side with O and the stabilities of the molecules decrease from 1 to 4, Ab initio results are in agreement with experimental results.
1990, 6(04): 403-409
doi: 10.3866/PKU.WHXB19900405
Abstract:
In this paper, the structure of ZnO-TiO_2 has been studied by XRD quantitative analysis and low energy ion scattering spectroscopy. The experimental results have shown that ZnO is dispersed on the surface of TiO_2 as a monolayer, the combination between ZnO and TiO_2 is quite weak and can not lead to the production of new surface acid sites.
In addition, the three kinds of binary metal oxides containing. ZnO (ZnO-Al_2O_3, ZnO-SiO_2 and ZnO-TiO_2) have been compared. The distinct differences among them in the structure and properties, and their origins have been discussed.
In this paper, the structure of ZnO-TiO_2 has been studied by XRD quantitative analysis and low energy ion scattering spectroscopy. The experimental results have shown that ZnO is dispersed on the surface of TiO_2 as a monolayer, the combination between ZnO and TiO_2 is quite weak and can not lead to the production of new surface acid sites.
In addition, the three kinds of binary metal oxides containing. ZnO (ZnO-Al_2O_3, ZnO-SiO_2 and ZnO-TiO_2) have been compared. The distinct differences among them in the structure and properties, and their origins have been discussed.
1990, 6(04): 410-417
doi: 10.3866/PKU.WHXB19900406
Abstract:
The complex dynamic behaviors, especially the behavior of transition between different states, of a closed reaction system which involves only bimolecular reactionsteps (A+B→C+D, B+C→2C) and unimolecular ones (B→P, E→A, G→B, A→D,C→P), is studied. By using the quasi-steady state analysis, a quasi-steady state bifurcation diagram, which predicts the existence of bistability between two different steady states or between a steady state and an oscillatory one, is obtained and confirmed by numerioal simulation. The numerical simuiations show that various transition transitions are trigged by external perturbations, and some may occur spontaneously. The numerical simulations also show that the system may exhibit the phenomena of excitation. All these phenomena are similar to those observed exprimentally in realistic closed reaction systems.
The complex dynamic behaviors, especially the behavior of transition between different states, of a closed reaction system which involves only bimolecular reactionsteps (A+B→C+D, B+C→2C) and unimolecular ones (B→P, E→A, G→B, A→D,C→P), is studied. By using the quasi-steady state analysis, a quasi-steady state bifurcation diagram, which predicts the existence of bistability between two different steady states or between a steady state and an oscillatory one, is obtained and confirmed by numerioal simulation. The numerical simuiations show that various transition transitions are trigged by external perturbations, and some may occur spontaneously. The numerical simulations also show that the system may exhibit the phenomena of excitation. All these phenomena are similar to those observed exprimentally in realistic closed reaction systems.
1990, 6(04): 418-424
doi: 10.3866/PKU.WHXB19900407
Abstract:
CO or/and NO co-adsorption on reduced Co/Al_2O_3, Mo/Al_2O_3 and Co-Mo/Al_2O_3 was studied by TPD-MS, IR and XPS. It was found that there exist two kinds of Mo-sites and three kinds of Co-sites on reduced Co-Mo/Al_2O_3. For Mo--sites, One is a weaker adsorption NO (T_(max): 100 ℃) which can be replaced by adsorption CO another is a stronger adsorption NO (T_(max): 300 ℃) which is not replaced by CO. Three kinds of Co--sites for NO adsorption emerged desorption peaks of NO at 80 ℃, 180 ℃ and 330 ℃ respectively. Former two can adsorb CO however, the latter only adsrb NO and all CO adsorbed on Co—sites can be replaced by co-adsorptoin NO.
Results of IR provided further evidence about existence of various Mo—sites and Co—sites. Results of XPS indicate that ratio of total Mo/Al is constant, but relative density of Mo~(4+) increase with reduction temperature. While ratio of Co/Al decrease due to Co on surface introduced in bulk phase of Al_2O_3 when reduction temperature raised. In this work it was not observed the existence of direct interaction between Co—sites and Mo—sites, which results in change of property relative to adsorption of CO and/or NO on Co—sites and/or Mo—sitews in the range of reduction temperature from 400 to 600 ℃.
CO or/and NO co-adsorption on reduced Co/Al_2O_3, Mo/Al_2O_3 and Co-Mo/Al_2O_3 was studied by TPD-MS, IR and XPS. It was found that there exist two kinds of Mo-sites and three kinds of Co-sites on reduced Co-Mo/Al_2O_3. For Mo--sites, One is a weaker adsorption NO (T_(max): 100 ℃) which can be replaced by adsorption CO another is a stronger adsorption NO (T_(max): 300 ℃) which is not replaced by CO. Three kinds of Co--sites for NO adsorption emerged desorption peaks of NO at 80 ℃, 180 ℃ and 330 ℃ respectively. Former two can adsorb CO however, the latter only adsrb NO and all CO adsorbed on Co—sites can be replaced by co-adsorptoin NO.
Results of IR provided further evidence about existence of various Mo—sites and Co—sites. Results of XPS indicate that ratio of total Mo/Al is constant, but relative density of Mo~(4+) increase with reduction temperature. While ratio of Co/Al decrease due to Co on surface introduced in bulk phase of Al_2O_3 when reduction temperature raised. In this work it was not observed the existence of direct interaction between Co—sites and Mo—sites, which results in change of property relative to adsorption of CO and/or NO on Co—sites and/or Mo—sitews in the range of reduction temperature from 400 to 600 ℃.
1990, 6(04): 425-429
doi: 10.3866/PKU.WHXB19900408
Abstract:
In this paper the complex plane figure of n-InP in Fe~(3+)/Fe~(2+) solution is analyzed by computer according to a equivalent circuit. The influences of electrode potential and light intensities are investigated and the result is discussed.
In this paper the complex plane figure of n-InP in Fe~(3+)/Fe~(2+) solution is analyzed by computer according to a equivalent circuit. The influences of electrode potential and light intensities are investigated and the result is discussed.
1990, 6(04): 430-436
doi: 10.3866/PKU.WHXB19900409
Abstract:
The distribution data for U(Ⅵ) from 0.25-5 mol·L~(-1) nitric acid media with 1--40 V% DHDECMP (dihexyl N,N-diethyl carbamoylmethyl phosphonate) in DEB (diethyl benzene) were determined in the temperature range 288--343 K. From the variation of the distribution ratios with temperature the enthalpy changes associated with the extraction were evaluated. Using extrapolation technique the thermodynamic value of the enthalpy (ΔH°_t) for zero ionic strength was obtained to be -27.5 kJ·mol~(-1). The thermodynamic equilibrium constant (K_t), free energy (ΔG°) and entropy changes (ΔS°) were calculated at 25 ℃ to be 1.15×10~3, -17.5 kJ·mol~(-1) and -33.5 J·mol~(-1)·K~(-1), respectively.
The distribution data for U(Ⅵ) from 0.25-5 mol·L~(-1) nitric acid media with 1--40 V% DHDECMP (dihexyl N,N-diethyl carbamoylmethyl phosphonate) in DEB (diethyl benzene) were determined in the temperature range 288--343 K. From the variation of the distribution ratios with temperature the enthalpy changes associated with the extraction were evaluated. Using extrapolation technique the thermodynamic value of the enthalpy (ΔH°_t) for zero ionic strength was obtained to be -27.5 kJ·mol~(-1). The thermodynamic equilibrium constant (K_t), free energy (ΔG°) and entropy changes (ΔS°) were calculated at 25 ℃ to be 1.15×10~3, -17.5 kJ·mol~(-1) and -33.5 J·mol~(-1)·K~(-1), respectively.
1990, 6(04): 437-444
doi: 10.3866/PKU.WHXB19900410
Abstract:
The chemiluminescent reactions of ClO_2 with Ca, Ba atoms have been studied under single collision condition in a beam-gas apparatus. The metastable states of the metal atoms are generated by the use of low valtage DC discharge. The Chemilu-minescence spectra have been observed and the spatial distributions of the intensities of the chemiluminescent emissions have been also measured by OMA-Ⅱ. The total reaction cross sections of metal atoms measured are 0.97 nm, 1.38 nm for Ca(~1S), Ca(~3P) and 1.36 nm, 2.39 nm for Ba(~1S), Ba(~3D) respectively. The intensities of the chemilu-minescence spectra are increased significantly when the metal atoms are excited to their metastable states. In particular, the increase of BaO(A′) is much more than that of BaCl(C) in the reaction of Ba(~3D)+ClO_2. In addition, non-Boltzmann vibrational distributions were found in the electronic excited state A′~1П of the products MO in both reactions by computer simulation. The chemiluminescent cross sections of the transition C~2П→X~2∑~+ of the products MCl are 0.51 nm for Ba(~3D)+ClO_2, 0.31 nm for Ca(~3P)+ClO_2 respectively. The branching ratios of the products MO and MCl were calculated based on the chemiluminescent spectra. A discussion about the mechanisms of these reactions is presented.
The chemiluminescent reactions of ClO_2 with Ca, Ba atoms have been studied under single collision condition in a beam-gas apparatus. The metastable states of the metal atoms are generated by the use of low valtage DC discharge. The Chemilu-minescence spectra have been observed and the spatial distributions of the intensities of the chemiluminescent emissions have been also measured by OMA-Ⅱ. The total reaction cross sections of metal atoms measured are 0.97 nm, 1.38 nm for Ca(~1S), Ca(~3P) and 1.36 nm, 2.39 nm for Ba(~1S), Ba(~3D) respectively. The intensities of the chemilu-minescence spectra are increased significantly when the metal atoms are excited to their metastable states. In particular, the increase of BaO(A′) is much more than that of BaCl(C) in the reaction of Ba(~3D)+ClO_2. In addition, non-Boltzmann vibrational distributions were found in the electronic excited state A′~1П of the products MO in both reactions by computer simulation. The chemiluminescent cross sections of the transition C~2П→X~2∑~+ of the products MCl are 0.51 nm for Ba(~3D)+ClO_2, 0.31 nm for Ca(~3P)+ClO_2 respectively. The branching ratios of the products MO and MCl were calculated based on the chemiluminescent spectra. A discussion about the mechanisms of these reactions is presented.
1990, 6(04): 445-448
doi: 10.3866/PKU.WHXB19900411
Abstract:
The reaction mechanism for dehydrogenation of silathione H_2SiS was studied by means of intrinsic reaction coordinate (IRC) method. The reaction er dography was analyzed by ab initio MO calculations using RHF/4-31G basis set. The equilibrium structure of H_2SiS which has C_(2υ). symmetry was optimized.The bond lengths of Si-S and Si-H are 0.2018 nm and 0.1484 nm, respectively. The bond angle of HSiS is 125.3°. The transition state was also located which has C_3 symmetry. The bondlengths of Si-S, Si-H_1 and Si-H_2 are 0.2045 nm, 0.1860 nm and 0.1522 nm, respectively. The bond angles of H_1SiS and H_2SiS are 105.0° and 147.4°, respectively. The activation energy was calculated to be 396.4 kJ·mol~(-1) and the reaction heat is 210.0 kJ·mol~(-1). The change of some physical properties along IRC were presented. At the same time, the vibrational analyses of the reactant and the transition state have also been done. At last, the frequency factor A of the reacton and the entropy of activation at 500 K were calculated with the application of RRKM theory. The results of H_2SiS were compared with its carbon analogy; thioformaldehyde CH_2S.
The reaction mechanism for dehydrogenation of silathione H_2SiS was studied by means of intrinsic reaction coordinate (IRC) method. The reaction er dography was analyzed by ab initio MO calculations using RHF/4-31G basis set. The equilibrium structure of H_2SiS which has C_(2υ). symmetry was optimized.The bond lengths of Si-S and Si-H are 0.2018 nm and 0.1484 nm, respectively. The bond angle of HSiS is 125.3°. The transition state was also located which has C_3 symmetry. The bondlengths of Si-S, Si-H_1 and Si-H_2 are 0.2045 nm, 0.1860 nm and 0.1522 nm, respectively. The bond angles of H_1SiS and H_2SiS are 105.0° and 147.4°, respectively. The activation energy was calculated to be 396.4 kJ·mol~(-1) and the reaction heat is 210.0 kJ·mol~(-1). The change of some physical properties along IRC were presented. At the same time, the vibrational analyses of the reactant and the transition state have also been done. At last, the frequency factor A of the reacton and the entropy of activation at 500 K were calculated with the application of RRKM theory. The results of H_2SiS were compared with its carbon analogy; thioformaldehyde CH_2S.
1990, 6(04): 449-455
doi: 10.3866/PKU.WHXB19900412
Abstract:
Mono-PPh_3- or mono-AsPh_3-substituted derivatives (μ-ArCO) (μ-RS) Fe_2(CO)_5PPh_3(Ar=Ph, R=Et or B_u~t; Ar=p-ClC_6H_4, R=B_u~t) and (μ-ArCO) (μ-RS)Fe_2(CO)_5AsPh_3 (Ar=Ph, R=Et or B_u~t) have been synthesized through reaction of the corresponding μ-acyl complexes (μ-ArCO) (μ-RS)Fe_2(CO)_6 with PPh_3 in boiling benzene for 2 h or with AsPh_3 in the same solvent refluxing for 12 h. For these new substituted derivatives the structures were characterized by combustion analysis, IR and ~1H NMR spectros. Furthermore, the crystal structure of one representative of these new complexes (μ-p-ClC_6H_4CO)(μ-B~t_uS)Fe_2(CO)_5PPh_3 has been determined by an X-ray diffraction technique. The crystals belong to triclinic system with space group P1. The cell parameters are a=1.0536(2), b=1.1714(4), c=1.4841(8) nm; α=98.47(4), β=102.70(4), γ=105.78(3)°; V=1.6771 nm; Z=2; D_C=1.468 g·cm~(-3). Final deviation factor R=0.065.
Mono-PPh_3- or mono-AsPh_3-substituted derivatives (μ-ArCO) (μ-RS) Fe_2(CO)_5PPh_3(Ar=Ph, R=Et or B_u~t; Ar=p-ClC_6H_4, R=B_u~t) and (μ-ArCO) (μ-RS)Fe_2(CO)_5AsPh_3 (Ar=Ph, R=Et or B_u~t) have been synthesized through reaction of the corresponding μ-acyl complexes (μ-ArCO) (μ-RS)Fe_2(CO)_6 with PPh_3 in boiling benzene for 2 h or with AsPh_3 in the same solvent refluxing for 12 h. For these new substituted derivatives the structures were characterized by combustion analysis, IR and ~1H NMR spectros. Furthermore, the crystal structure of one representative of these new complexes (μ-p-ClC_6H_4CO)(μ-B~t_uS)Fe_2(CO)_5PPh_3 has been determined by an X-ray diffraction technique. The crystals belong to triclinic system with space group P1. The cell parameters are a=1.0536(2), b=1.1714(4), c=1.4841(8) nm; α=98.47(4), β=102.70(4), γ=105.78(3)°; V=1.6771 nm; Z=2; D_C=1.468 g·cm~(-3). Final deviation factor R=0.065.
1990, 6(04): 456-464
doi: 10.3866/PKU.WHXB19900413
Abstract:
The properties of the n-electron wavefunctions Ψ_(n, s_1, s_2)=NQ_+~s1(ξ) multiply from t=1 to 2 a_t~+_(a_t)G~+(ξ, r, v_(r+1)|0> with symplectic symmetries have been discussed. This kind of wavefunctions is ageneralization of n-electron wavefunctions with two kinds of geminals, and they are suitable for both closed-shell and open-shell systems . As illustrations, the ground states of Li_2, LiH_2~-, CH_3~+ and OH~- are calculated. The calculated results show that this kind of wavefunctions is capable of describing the electron correlations.
The properties of the n-electron wavefunctions Ψ_(n, s_1, s_2)=NQ_+~s1(ξ) multiply from t=1 to 2 a_t~+_(a_t)G~+(ξ, r, v_(r+1)|0> with symplectic symmetries have been discussed. This kind of wavefunctions is ageneralization of n-electron wavefunctions with two kinds of geminals, and they are suitable for both closed-shell and open-shell systems . As illustrations, the ground states of Li_2, LiH_2~-, CH_3~+ and OH~- are calculated. The calculated results show that this kind of wavefunctions is capable of describing the electron correlations.
1990, 6(04): 465-469
doi: 10.3866/PKU.WHXB19900414
Abstract:
In this work we have studied the phase diagrams of SDS-Water-Butanol and SDS-Water-Butanol-Heptane system. The structure of lamellar liquid crystal in both systems have studied by low angle X-ray diffraction. The result showed that the thickness of amphiphile bilayer of lamellar liquid crystal in SDS-Water-Butanol system was 2.42 nm, it did not vary with SDS/Butanol ratio. When heptane was solubilized in the lamellar liquid crystal, the solubilization caused the thickness of amphiphile bilayer to increase. While the water penetrated into the amphiphile bilayer, the thickness decreased accordingly.
In this work we have studied the phase diagrams of SDS-Water-Butanol and SDS-Water-Butanol-Heptane system. The structure of lamellar liquid crystal in both systems have studied by low angle X-ray diffraction. The result showed that the thickness of amphiphile bilayer of lamellar liquid crystal in SDS-Water-Butanol system was 2.42 nm, it did not vary with SDS/Butanol ratio. When heptane was solubilized in the lamellar liquid crystal, the solubilization caused the thickness of amphiphile bilayer to increase. While the water penetrated into the amphiphile bilayer, the thickness decreased accordingly.
1990, 6(04): 470-473
doi: 10.3866/PKU.WHXB19900415
Abstract:
This paper reported application of In Situ LPSIRS (linear potential sweep infrared reflectance spectroscopy) technique to get precise spectroscopy information about electropolymerization of 2,6-dimethylphenol on ld electrode in base methanol solution and propose the electropolymerization mechanism under the conditions. From the spectra it has been found that the DMP~- ion was cosumed and PPO polymer was produced during cyclic voltammetry. At the same time, it has been deduced that the methanol in the case probably takes part in the electropolymerization partly. The electropolymerization mechanism of 2,6-dimethylphenol in base methanol is a sequence of alternating ionic and radical steps; the propagation occurs by coupling of two phenate radicals.
This paper reported application of In Situ LPSIRS (linear potential sweep infrared reflectance spectroscopy) technique to get precise spectroscopy information about electropolymerization of 2,6-dimethylphenol on ld electrode in base methanol solution and propose the electropolymerization mechanism under the conditions. From the spectra it has been found that the DMP~- ion was cosumed and PPO polymer was produced during cyclic voltammetry. At the same time, it has been deduced that the methanol in the case probably takes part in the electropolymerization partly. The electropolymerization mechanism of 2,6-dimethylphenol in base methanol is a sequence of alternating ionic and radical steps; the propagation occurs by coupling of two phenate radicals.
1990, 6(04): 474-479
doi: 10.3866/PKU.WHXB19900416
Abstract:
TiO_2-Al_2O_3 binary oxides were prepared by precipitation from TiCl_4 solution with aqueous ammonia; impregnation, using evaporation from titanium isoproxide in iso-propanol; and grafting, using reaction of TiCl_4 vapour with OH~- group on Al_2O_3 surface.
AEM was used to examine the morphology of TiO_2 on Al_2O_3. The results show that relative homogeneous distribution of TiO_2 on Al_2O_3 could be formed for im-pregnated samples when TiO_2 loading was not beyond one monolayer. A quite homo-geneous coverage of TiO_2 was obtained for grafting samples through anchoring of TiCl_4 molecule on OH~- group of Al_2O_3 surface. As for precipitated samples the distribution of TiO_2 was rather poor. TiO_2 covered only a part of Al_2O_3 surface.
TiO_2-Al_2O_3 binary oxides were prepared by precipitation from TiCl_4 solution with aqueous ammonia; impregnation, using evaporation from titanium isoproxide in iso-propanol; and grafting, using reaction of TiCl_4 vapour with OH~- group on Al_2O_3 surface.
AEM was used to examine the morphology of TiO_2 on Al_2O_3. The results show that relative homogeneous distribution of TiO_2 on Al_2O_3 could be formed for im-pregnated samples when TiO_2 loading was not beyond one monolayer. A quite homo-geneous coverage of TiO_2 was obtained for grafting samples through anchoring of TiCl_4 molecule on OH~- group of Al_2O_3 surface. As for precipitated samples the distribution of TiO_2 was rather poor. TiO_2 covered only a part of Al_2O_3 surface.
1990, 6(04): 480-484
doi: 10.3866/PKU.WHXB19900417
Abstract:
The cathodic deposition mechanism of CdSe films on Ti substrates was investigated using cyclic voltammetry and in-situ photocurrent mesurements. XPS analysis showed that CdSe film composition depends on deposition potentials, deposition time and concentration of H_2SeO_3 in the bath. It was found that in 0.1 mol·L~(-1) CdSO_4+4 mmol·L~(-1) H_2SeO_3+0.2 mol·L~(-1) H_2SO_4, the deposits formed at potentials more positive than -0.50 V are rich in Se, alternatively films rich in Cd are obtained at potentials more negative than -0.70 V. The Se/Cd ratio of CdSe layers deposited at -0.69 V approach to 1.1, but the content of Se in the deposits increases with increasing H_2SeO_3 concentration. The results showed that the electrodeposition of CdSe follows two different mechanisms corresponding to different deposition conditions. Modification of stoichiometry in CdSe films was also discussed.
The cathodic deposition mechanism of CdSe films on Ti substrates was investigated using cyclic voltammetry and in-situ photocurrent mesurements. XPS analysis showed that CdSe film composition depends on deposition potentials, deposition time and concentration of H_2SeO_3 in the bath. It was found that in 0.1 mol·L~(-1) CdSO_4+4 mmol·L~(-1) H_2SeO_3+0.2 mol·L~(-1) H_2SO_4, the deposits formed at potentials more positive than -0.50 V are rich in Se, alternatively films rich in Cd are obtained at potentials more negative than -0.70 V. The Se/Cd ratio of CdSe layers deposited at -0.69 V approach to 1.1, but the content of Se in the deposits increases with increasing H_2SeO_3 concentration. The results showed that the electrodeposition of CdSe follows two different mechanisms corresponding to different deposition conditions. Modification of stoichiometry in CdSe films was also discussed.
1990, 6(04): 485-490
doi: 10.3866/PKU.WHXB19900418
Abstract:
Partial molal volumes of ethanol, cyclohaxane, trichloromethane, toluene, acetone, carbon tetrachloride, acetonitrile, DMF, and DMSO in methanol, benzene, and their mixtures at infinite dilution at 298.15 K were determined with density measurement. The concentration of solutes for density measurement is in the range from 0.2 to 1.5 mol·kg~(-1) solvent. The compositions of methanol-benzene mixture lay between mole fraction 0 and 1. Variation of solute partial molal volumes with composition of methanol-benzene mixture was attributed to several aspects of molecular interaction, i.e. physical type interaction among three kinds of molecules; hydrogen bond asociation between solute and methanol molecules; and weak complex between solute and methanol or benzene.
Partial molal volumes of ethanol, cyclohaxane, trichloromethane, toluene, acetone, carbon tetrachloride, acetonitrile, DMF, and DMSO in methanol, benzene, and their mixtures at infinite dilution at 298.15 K were determined with density measurement. The concentration of solutes for density measurement is in the range from 0.2 to 1.5 mol·kg~(-1) solvent. The compositions of methanol-benzene mixture lay between mole fraction 0 and 1. Variation of solute partial molal volumes with composition of methanol-benzene mixture was attributed to several aspects of molecular interaction, i.e. physical type interaction among three kinds of molecules; hydrogen bond asociation between solute and methanol molecules; and weak complex between solute and methanol or benzene.
1990, 6(04): 491-494
doi: 10.3866/PKU.WHXB19900419
Abstract:
The heterogeneous decomposition of 2-propanol in the presence of CuO powder had been induced by TEA CO_2 laser radiation. Two different reaction channels were observed. Yields and branching ratios are quite sensitive to experimental variables, such as the frequency and energy fluence of laser, the distance between the laser beam and CuO surface and the nature of buffer gas.
The heterogeneous decomposition of 2-propanol in the presence of CuO powder had been induced by TEA CO_2 laser radiation. Two different reaction channels were observed. Yields and branching ratios are quite sensitive to experimental variables, such as the frequency and energy fluence of laser, the distance between the laser beam and CuO surface and the nature of buffer gas.
1990, 6(04): 495-498
doi: 10.3866/PKU.WHXB19900420
Abstract:
The formation constants of ternary mixed ligand complex compounds (logK_(MAB~(MA)) formed from 1,10-phenanthroline or 2,2'-bipyridyl (A), N-(meta-substituted phenyl) glycines, (B, m-RphG, R=CH_3, H, CH_3O, Cl) with Nickel(Ⅱ), Cobalt(Ⅱ) and Zinc(Ⅱ) were determined by pH method at 25 ℃ in 30% (Volume) ethanol solution in presence of 0.1 mol·dm~(-3) NaClO_4 or 0.1 mol·dm~(-3) KNO_3. It was found that linear free energy relationships exist between the stability of ternary complex compounds and the base strengths of ligands in all six ternary systems investigated. The stability of the ternary complex compounds was discused in terms of ΔlogK_M values and HSAB theory. It was found that linear relationships also exist between ΔlogK_M and pK_2 in the Ni(II)-phen-m-RPhG ternary system.
The formation constants of ternary mixed ligand complex compounds (logK_(MAB~(MA)) formed from 1,10-phenanthroline or 2,2'-bipyridyl (A), N-(meta-substituted phenyl) glycines, (B, m-RphG, R=CH_3, H, CH_3O, Cl) with Nickel(Ⅱ), Cobalt(Ⅱ) and Zinc(Ⅱ) were determined by pH method at 25 ℃ in 30% (Volume) ethanol solution in presence of 0.1 mol·dm~(-3) NaClO_4 or 0.1 mol·dm~(-3) KNO_3. It was found that linear free energy relationships exist between the stability of ternary complex compounds and the base strengths of ligands in all six ternary systems investigated. The stability of the ternary complex compounds was discused in terms of ΔlogK_M values and HSAB theory. It was found that linear relationships also exist between ΔlogK_M and pK_2 in the Ni(II)-phen-m-RPhG ternary system.
1990, 6(04): 499-503
doi: 10.3866/PKU.WHXB19900421
Abstract:
The eleven title compounds are classified into three series according to their molecular structure having mono-, bi- and tri-condensed ring system, respectively. For each series the hydrolytic stabilities decrease with the increase of the calculated CNDO/2 net positive charge on C atom of carbonyl group. This relation supports the kinetic hydrolysis mechanism, in which the hydrolysis reaction is initiated by the nucleophylic attack on the C atom of the carbonyl group. It can be applied to predict the relative stsbility of some cyclourea nitroamines by means of similar theoretically calculated parameters. For bi- and tri-condensed ring compounds, which have V- and U-type optimized configurations respecively, the steric hindrance due to the C=O group covering large —CH_2C(NO_2)_3 group plays an important role also, especially for the V-type bi-condensed ring compounds.
The eleven title compounds are classified into three series according to their molecular structure having mono-, bi- and tri-condensed ring system, respectively. For each series the hydrolytic stabilities decrease with the increase of the calculated CNDO/2 net positive charge on C atom of carbonyl group. This relation supports the kinetic hydrolysis mechanism, in which the hydrolysis reaction is initiated by the nucleophylic attack on the C atom of the carbonyl group. It can be applied to predict the relative stsbility of some cyclourea nitroamines by means of similar theoretically calculated parameters. For bi- and tri-condensed ring compounds, which have V- and U-type optimized configurations respecively, the steric hindrance due to the C=O group covering large —CH_2C(NO_2)_3 group plays an important role also, especially for the V-type bi-condensed ring compounds.
1990, 6(04): 504-508
doi: 10.3866/PKU.WHXB19900422
Abstract:
A method is proposed to calculate vibrational frequencies and intensities of an adsorbed molecule system with P2mm or P4 symmetry. The method can be used if the system can be considered as a group of coupled oscillators with one freedom per oscillator. The stretch vibrations and lateral interactions of CO molecules adsorbed on Cu(100) face are studied by means of this method. The calculated results show that the lateral force constants have a strong dependence on interaction range assumed. The size effects on vibrational frequencies of adsorbed system are also examined. The results given here are to be expected.
A method is proposed to calculate vibrational frequencies and intensities of an adsorbed molecule system with P2mm or P4 symmetry. The method can be used if the system can be considered as a group of coupled oscillators with one freedom per oscillator. The stretch vibrations and lateral interactions of CO molecules adsorbed on Cu(100) face are studied by means of this method. The calculated results show that the lateral force constants have a strong dependence on interaction range assumed. The size effects on vibrational frequencies of adsorbed system are also examined. The results given here are to be expected.
1990, 6(04): 509-512
doi: 10.3866/PKU.WHXB19900423
Abstract:
The diffusion of ethanol, urea, glucose and sucrose into gel beads which are prepared from the equeous solutions of poly(vinyl alcohol) (PVA) has been investi gated. The diffusion coefficients of those small molecule matters in gel beads have much to do with temperature and the free-water content and the pore size of the gels. The structure of gel beads, which determines the pore size of the gels, depends on the concentration of PVA gels, freezing time and preparation method of gel beads. The diffusion coefficients of the above mentioned matters in the gels increase with the rise of temperature, and do with their concentrations at given freezing time. The diffusion coefficient of sucrose in the gels decreases, but the diffusion coefficients of ethanol, urea and glucose increase, with the increase of freezing time at a given concentration.
The diffusion of ethanol, urea, glucose and sucrose into gel beads which are prepared from the equeous solutions of poly(vinyl alcohol) (PVA) has been investi gated. The diffusion coefficients of those small molecule matters in gel beads have much to do with temperature and the free-water content and the pore size of the gels. The structure of gel beads, which determines the pore size of the gels, depends on the concentration of PVA gels, freezing time and preparation method of gel beads. The diffusion coefficients of the above mentioned matters in the gels increase with the rise of temperature, and do with their concentrations at given freezing time. The diffusion coefficient of sucrose in the gels decreases, but the diffusion coefficients of ethanol, urea and glucose increase, with the increase of freezing time at a given concentration.
