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2001 Volume 17 Issue 11
2001, 17(11): 961-965
doi: 10.3866/PKU.WHXB20011101
Abstract:
Quasiordered, stripelike, nanometerscale structures were spontaneously created on surfaces of highpurity(99.999％) aluminum by electropolishing. Observed under atomic force microscopy(AFM), the average width of single stripe and the distance between two neighboring stripes are about 40～50 nm,respectively, and the average height of the stripes is 1.5～5.0 nm. The highly ordered stripelike nanostructures can be obtained only within a narrow range of processing parameters. The stripe deficiencies, such as stripecross and stripeconvergence, within parallel stripes, can be seen on surface defects, which do not fundamentally affect the orientation of the stripes. The stripe structures are stable in atmosphere at room temperature. When samples with stripe structures were anodized to form porous alumina, the stripe structures vanished. A physical scenario was proposed to explain the growth mechanisms of the quasiordered stripelike structures.
Quasiordered, stripelike, nanometerscale structures were spontaneously created on surfaces of highpurity(99.999％) aluminum by electropolishing. Observed under atomic force microscopy(AFM), the average width of single stripe and the distance between two neighboring stripes are about 40～50 nm,respectively, and the average height of the stripes is 1.5～5.0 nm. The highly ordered stripelike nanostructures can be obtained only within a narrow range of processing parameters. The stripe deficiencies, such as stripecross and stripeconvergence, within parallel stripes, can be seen on surface defects, which do not fundamentally affect the orientation of the stripes. The stripe structures are stable in atmosphere at room temperature. When samples with stripe structures were anodized to form porous alumina, the stripe structures vanished. A physical scenario was proposed to explain the growth mechanisms of the quasiordered stripelike structures.
2001, 17(11): 966-971
doi: 10.3866/PKU.WHXB20011102
Abstract:
Two series of M /HZSM-5 catalysts were prepared by impregnating HZSM-5 with solution of Mg(NO3)2 and Mg(CH3COO)2.The structures of the samples were characterized by XRD and XPS,and the acidity was determined by NH3-TPD.The catalytic behavior of M /HZSM-5 in the reaction of toluene methylation was investigated on a continuous flow micro-apparatus under atmospheric pressure.It was found that the dispersion of M was related to the precursor of M and had an important effect on the behavior of M /HZSM-5 catalyst.M disperses both on the internal surface and on the external surface of HZSM-5 in the catalysts prepared with Mg(NO3)2 as the precursor of M ,therefore the para-selectivity of the catalyst is higher and the activity is lower.However M mainly deposits on the external surface of HZSM-5 in the catalysts prepared with Mg(CH3COO)2,and the activity of catalysts is higher and the para-selectivity is lower.By secondary impregnation and hydrothermal treatment M /HZSM-5 catalyst with relatively high activity and high para-selectivity was obtained.
Two series of M /HZSM-5 catalysts were prepared by impregnating HZSM-5 with solution of Mg(NO3)2 and Mg(CH3COO)2.The structures of the samples were characterized by XRD and XPS,and the acidity was determined by NH3-TPD.The catalytic behavior of M /HZSM-5 in the reaction of toluene methylation was investigated on a continuous flow micro-apparatus under atmospheric pressure.It was found that the dispersion of M was related to the precursor of M and had an important effect on the behavior of M /HZSM-5 catalyst.M disperses both on the internal surface and on the external surface of HZSM-5 in the catalysts prepared with Mg(NO3)2 as the precursor of M ,therefore the para-selectivity of the catalyst is higher and the activity is lower.However M mainly deposits on the external surface of HZSM-5 in the catalysts prepared with Mg(CH3COO)2,and the activity of catalysts is higher and the para-selectivity is lower.By secondary impregnation and hydrothermal treatment M /HZSM-5 catalyst with relatively high activity and high para-selectivity was obtained.
2001, 17(11): 972-977
doi: 10.3866/PKU.WHXB20011103
Abstract:
The surface properties of hydrolytic surfactants,sodium alkycarboxylate and alkylammonium chlorides,were investigated systematically.lt is found that the variation of pH,salt and temperature have obvious influence on the surface properties and micellization of the system.Due to hydrolysis of the surfactants,the systems have high surface activity.It is interesting to note that the variation of pH still has an obvious influence on the surface properties of sodium alkycarboxylate at pH ≥ 9.2.In contrast,the surface properties and micellization of alkylammonium chlorides are mainly affected by adding salt rather than pH at pH ≤ 6.06,indicating the different hydrolysate effect in these two kinds of surfactant systems.The standard thermodynamic parameters of micellzation have been calculated according to the model of charged pseudophased separation,and the effect of temperature on hydrolytic surfactants has also been studied.
The surface properties of hydrolytic surfactants,sodium alkycarboxylate and alkylammonium chlorides,were investigated systematically.lt is found that the variation of pH,salt and temperature have obvious influence on the surface properties and micellization of the system.Due to hydrolysis of the surfactants,the systems have high surface activity.It is interesting to note that the variation of pH still has an obvious influence on the surface properties of sodium alkycarboxylate at pH ≥ 9.2.In contrast,the surface properties and micellization of alkylammonium chlorides are mainly affected by adding salt rather than pH at pH ≤ 6.06,indicating the different hydrolysate effect in these two kinds of surfactant systems.The standard thermodynamic parameters of micellzation have been calculated according to the model of charged pseudophased separation,and the effect of temperature on hydrolytic surfactants has also been studied.
2001, 17(11): 978-981
doi: 10.3866/PKU.WHXB20011104
Abstract:
We report in this paper the formation of new fullereneterminated selfassembled monolayers(SAMs) from the adsorption of unsymmetrical dialkylmonosulfide compound onto the Au(111) substrate via ldsulfur bonding. The highresolution STM images verified that C60 moieties are located at the outer surface and the XPS results provided clear evidence for S－C cleavage and Au－S bonding during the selfassembling process of this specific C60organosulfide on ld.
We report in this paper the formation of new fullereneterminated selfassembled monolayers(SAMs) from the adsorption of unsymmetrical dialkylmonosulfide compound onto the Au(111) substrate via ldsulfur bonding. The highresolution STM images verified that C60 moieties are located at the outer surface and the XPS results provided clear evidence for S－C cleavage and Au－S bonding during the selfassembling process of this specific C60organosulfide on ld.
2001, 17(11): 982-985
doi: 10.3866/PKU.WHXB20011105
Abstract:
The location of phenothiazine in SDS/BA/H2O microemulsion was investigated by cyclic voltammetric and fluorescence quenching method.In O/W microemulsion,phenothiazine has two oxidation peaks.Because the peak potentials are independent of the sweep rate ( Fig.1 ) and all the peak currents are proportional to the square root of the potential sweep rate ( Fig.2 ),the electrochemical process for phenothiazine is reversible.According to the peak separation between the peak potentials in the positive and negative scans and the Nernstian equation,the above cyclic voltammetric characteristics for all peaks are of one - electron process.Since the process of the radical cation PTZ＋•losing an electron to form PTZ2＋ needs much more energy (≈0.4 V ) and there is only about 0.13 V between the two peaks ( table 1,Fig.1 ),the two peaks are both produced by the process of PTZ molecule losing an electron.In PTZ molecules,there are two polar groups with the S and N atoms as center,respectively.Thus,the phenothiazine molecules exist in the membrane phase with its N atom or S atom extended toward the polar head in the O/W microemulsion.Further experiments found that the fluorescence quenching of anthracene by PTZ in the W/O microemulsion is rather more similar to that in the O/W microemulsion than in pure benzyl alcohol.So,the location of PTZ in the W/O microemulsion is the same as in the O/W microemulsion,i.e.,in the inner side of the membrane phase of the W/O microemulsion.
The location of phenothiazine in SDS/BA/H2O microemulsion was investigated by cyclic voltammetric and fluorescence quenching method.In O/W microemulsion,phenothiazine has two oxidation peaks.Because the peak potentials are independent of the sweep rate ( Fig.1 ) and all the peak currents are proportional to the square root of the potential sweep rate ( Fig.2 ),the electrochemical process for phenothiazine is reversible.According to the peak separation between the peak potentials in the positive and negative scans and the Nernstian equation,the above cyclic voltammetric characteristics for all peaks are of one - electron process.Since the process of the radical cation PTZ＋•losing an electron to form PTZ2＋ needs much more energy (≈0.4 V ) and there is only about 0.13 V between the two peaks ( table 1,Fig.1 ),the two peaks are both produced by the process of PTZ molecule losing an electron.In PTZ molecules,there are two polar groups with the S and N atoms as center,respectively.Thus,the phenothiazine molecules exist in the membrane phase with its N atom or S atom extended toward the polar head in the O/W microemulsion.Further experiments found that the fluorescence quenching of anthracene by PTZ in the W/O microemulsion is rather more similar to that in the O/W microemulsion than in pure benzyl alcohol.So,the location of PTZ in the W/O microemulsion is the same as in the O/W microemulsion,i.e.,in the inner side of the membrane phase of the W/O microemulsion.
2001, 17(11): 986-990
doi: 10.3866/PKU.WHXB20011106
Abstract:
Low energy ions were produced by N2 glowdischarge. The positive ones were accelerated into acetone solution with D2O as solvent to induce chemical reactions. GCMS analysis showed that CH3COCH2D, CH3COCH2OD were produced by such kind of implantation.Thus, it was proved that the reaction was mainly caused by radicals generated by decomposition of water molecules, and played an important role in the process. Meanwhile, CH3COOD and CH3COCH2ND2 were also found in the products, so it was concluded that the reaction was carried out under an oxidative atmosphere. The capture of D from D2O by N＋ to form radicals was not only an initial step to produce CH3COCH2ND2 but also served as a probable pattern for “nitrogen deposition”. All these were helpful to reveal the mechanism of the reaction induced by low energy N＋ implanting into solution samples.
Low energy ions were produced by N2 glowdischarge. The positive ones were accelerated into acetone solution with D2O as solvent to induce chemical reactions. GCMS analysis showed that CH3COCH2D, CH3COCH2OD were produced by such kind of implantation.Thus, it was proved that the reaction was mainly caused by radicals generated by decomposition of water molecules, and played an important role in the process. Meanwhile, CH3COOD and CH3COCH2ND2 were also found in the products, so it was concluded that the reaction was carried out under an oxidative atmosphere. The capture of D from D2O by N＋ to form radicals was not only an initial step to produce CH3COCH2ND2 but also served as a probable pattern for “nitrogen deposition”. All these were helpful to reveal the mechanism of the reaction induced by low energy N＋ implanting into solution samples.
2001, 17(11): 991-994
doi: 10.3866/PKU.WHXB20011107
Abstract:
Highly ordered nanoporous nickel membranes were fabricated by a two-step replication of porous anodic alumina with honeycomb structure. SEM analysis shows that the nanoholes of nickel membranes are hexa nally arranged in high regularity. The mean diameter and the interval of the holes measured from the SEM micrograph are about 40 nm and 80 nm,respectively. The mean diameter of the hole array was dependent on the corresponding parameter of the porous anodic alumina. Compared with alumina membranes,the nanoporous metal ones have many advantages in more sufficient thermal,chemical stability and higher mechanical strength. Serving as a magnetic and conductive material,the nickel membrane template will be used for many technological and scientific applications. The presented process could be utilized to fabricate nanostrctures of other nanochannel materials.
Highly ordered nanoporous nickel membranes were fabricated by a two-step replication of porous anodic alumina with honeycomb structure. SEM analysis shows that the nanoholes of nickel membranes are hexa nally arranged in high regularity. The mean diameter and the interval of the holes measured from the SEM micrograph are about 40 nm and 80 nm,respectively. The mean diameter of the hole array was dependent on the corresponding parameter of the porous anodic alumina. Compared with alumina membranes,the nanoporous metal ones have many advantages in more sufficient thermal,chemical stability and higher mechanical strength. Serving as a magnetic and conductive material,the nickel membrane template will be used for many technological and scientific applications. The presented process could be utilized to fabricate nanostrctures of other nanochannel materials.
2001, 17(11): 995-999
doi: 10.3866/PKU.WHXB20011108
Abstract:
Noncentrosymmetric Ytype alternating NMOB/CdA multilayers were prepared for applications of LB films in waveguidetype second harmonic generation (SHG) devices. Two kinds of methods were put forward to improve the quality of NMOB/CdA alternating multilayers, which possess nearquadratic dependence of SHG intensities on layer number. 115 bilayers of NMOB/CdA multilayers film was fabricated which met Cerenkov phasematching condition, and SHG at 1064 nm wavelength from this waveguide was measured. The preliminary results show that the improved multilayer LB films are suitable for fabricating waveguide.
Noncentrosymmetric Ytype alternating NMOB/CdA multilayers were prepared for applications of LB films in waveguidetype second harmonic generation (SHG) devices. Two kinds of methods were put forward to improve the quality of NMOB/CdA alternating multilayers, which possess nearquadratic dependence of SHG intensities on layer number. 115 bilayers of NMOB/CdA multilayers film was fabricated which met Cerenkov phasematching condition, and SHG at 1064 nm wavelength from this waveguide was measured. The preliminary results show that the improved multilayer LB films are suitable for fabricating waveguide.
2001, 17(11): 1000-1005
doi: 10.3866/PKU.WHXB20011109
Abstract:
The kinetic process in a tubular continuous-flow photo-reactor equiped with titanium dioxide immobilized on glass fiber-net has been studied by using methyl orange as a model reactant.The process has been described carefully,and modeled by using dynamic partial differential equation.Since the solution of the equation was complicated,the numerical solution has been undertaken by using a fourth-order Runge-Kutta scheme.The results show that the mathematical simulated values are consistent with the experimental data.Under the condition of different treated reactant amount the actual reaction rate constant k is approximately identical,but the apparent reaction rate constant kapp decreases with increasing treatment of reactant amount.The initial concentration has a great influence upon the rate constant.Below 15 μmol•L－1 of the initial concentration the rate constant tends to be a constant.In the range of 15～150 μmol•L－1,the influence of the initial concentration on the reaction rate constant can be expressed as:lnk=－0.48lnc0＋1.42.The dependence of reaction rate constant on UV irradiation intensity is k∝I 0.5.The pH of initial solution is an important factor in the photocatalysis reaction.
The kinetic process in a tubular continuous-flow photo-reactor equiped with titanium dioxide immobilized on glass fiber-net has been studied by using methyl orange as a model reactant.The process has been described carefully,and modeled by using dynamic partial differential equation.Since the solution of the equation was complicated,the numerical solution has been undertaken by using a fourth-order Runge-Kutta scheme.The results show that the mathematical simulated values are consistent with the experimental data.Under the condition of different treated reactant amount the actual reaction rate constant k is approximately identical,but the apparent reaction rate constant kapp decreases with increasing treatment of reactant amount.The initial concentration has a great influence upon the rate constant.Below 15 μmol•L－1 of the initial concentration the rate constant tends to be a constant.In the range of 15～150 μmol•L－1,the influence of the initial concentration on the reaction rate constant can be expressed as:lnk=－0.48lnc0＋1.42.The dependence of reaction rate constant on UV irradiation intensity is k∝I 0.5.The pH of initial solution is an important factor in the photocatalysis reaction.
2001, 17(11): 1006-1012
doi: 10.3866/PKU.WHXB20011110
Abstract:
The interactional potential of O－Ni surface system was simulated by means of the 5-parameter.Morse potential,the adsorptive characteristics of an oxygen atom on low index nickel surface.An extended LEPS potential for the OH－Ni surface system was constructed.Data of adsorption sites,adsorption geometry,binding energy and eigenvibration etc.were obtained.These results show that high-symmetry sites are the most stable sites for OH perpendicular adsorption.Adsorption energies for OH perpendicular adsorption are 109.45 kJ•mol－1 at 4-fold hollow site on Ni (100),96.00 kJ•mol－1 at 3-fold hollow site on Ni (111).However,there are two adsorptive sites on Ni(110):one is the perpendicular adsorption at long-bridge site with adsorptive energy 99.38 kJ•mol－1 ;the other is a 14° inclined from the surface normal at phoney 3-fold site on Ni (110) with adsorptive energy 96.98 kJ•mol－1,the calculated results are in od agreement with the experimental ones.
The interactional potential of O－Ni surface system was simulated by means of the 5-parameter.Morse potential,the adsorptive characteristics of an oxygen atom on low index nickel surface.An extended LEPS potential for the OH－Ni surface system was constructed.Data of adsorption sites,adsorption geometry,binding energy and eigenvibration etc.were obtained.These results show that high-symmetry sites are the most stable sites for OH perpendicular adsorption.Adsorption energies for OH perpendicular adsorption are 109.45 kJ•mol－1 at 4-fold hollow site on Ni (100),96.00 kJ•mol－1 at 3-fold hollow site on Ni (111).However,there are two adsorptive sites on Ni(110):one is the perpendicular adsorption at long-bridge site with adsorptive energy 99.38 kJ•mol－1 ;the other is a 14° inclined from the surface normal at phoney 3-fold site on Ni (110) with adsorptive energy 96.98 kJ•mol－1,the calculated results are in od agreement with the experimental ones.
2001, 17(11): 1013-1020
doi: 10.3866/PKU.WHXB20011111
Abstract:
The potential energy surfaces of the ground state of the HeHF complex have been calculated at several levels of theory, including the single and double excitation coupledcluster method with noniterative perturbation treatment of triple excitation CCSD(T). Calculations have been performed using the augmented correlationconsistent polarized quadruple zeta basis set(augccpVQZ). Using the complete basis set (CBS), the global minimum with a well depth of approximately 46.614 cm－1 has been found for the linear HeHF geometry (θ=0°) with the distance Rm between the He atom and the center of mass of the HF molecule equal to 0.3149 nm. In addition to the global minimum, there is a second minimum at R=0.3012 nm and θ=180° (a well depth of 25.026 cm－1). The effects of the basis sets, H－F bond length and theoretical methods on the intermolecular potential were discussed and a simple analytic form employing 17 adjustable parameters for fitting to the calculated PES was given.
The potential energy surfaces of the ground state of the HeHF complex have been calculated at several levels of theory, including the single and double excitation coupledcluster method with noniterative perturbation treatment of triple excitation CCSD(T). Calculations have been performed using the augmented correlationconsistent polarized quadruple zeta basis set(augccpVQZ). Using the complete basis set (CBS), the global minimum with a well depth of approximately 46.614 cm－1 has been found for the linear HeHF geometry (θ=0°) with the distance Rm between the He atom and the center of mass of the HF molecule equal to 0.3149 nm. In addition to the global minimum, there is a second minimum at R=0.3012 nm and θ=180° (a well depth of 25.026 cm－1). The effects of the basis sets, H－F bond length and theoretical methods on the intermolecular potential were discussed and a simple analytic form employing 17 adjustable parameters for fitting to the calculated PES was given.
2001, 17(11): 1021-1026
doi: 10.3866/PKU.WHXB20011112
Abstract:
The supersaturated solution of M •3B2O3-18％MgSO4-H2O was prepared and kept in a thermostat of (20±0.1) ℃.The crystallization processes of Mg-borates from the solution have been studied by the kinetic method .With the aid of simplex optinum method and digital integration as well as runge-kutta digital solution of differential equation system,the experimental data have been fitted and the kinetic parameters have been evaluated by computer.The crystallization kinetic equation has been given.There are two solid phases ,Macallisterite (M •3B2O3•7.5H2O) was firstly crystallized out from the solution and then hungchaoite (M •2B2O3•9H2O).The solid phases were identified by IR-spectra,X-ray powder diffraction and TG-DSC thermal analysis.
The supersaturated solution of M •3B2O3-18％MgSO4-H2O was prepared and kept in a thermostat of (20±0.1) ℃.The crystallization processes of Mg-borates from the solution have been studied by the kinetic method .With the aid of simplex optinum method and digital integration as well as runge-kutta digital solution of differential equation system,the experimental data have been fitted and the kinetic parameters have been evaluated by computer.The crystallization kinetic equation has been given.There are two solid phases ,Macallisterite (M •3B2O3•7.5H2O) was firstly crystallized out from the solution and then hungchaoite (M •2B2O3•9H2O).The solid phases were identified by IR-spectra,X-ray powder diffraction and TG-DSC thermal analysis.
2001, 17(11): 1027-1030
doi: 10.3866/PKU.WHXB20011113
Abstract:
The phase behavior diagram has been drawn and analysed in DTAB－SL mixed system and the influences of temperature and inorganic salt upon “aqueous surfactant twophase(ASTP)” have been studied systematically. The results show that ASTP region when cationics is in excess(ASTPC) is larger and stabler than that when anionics is in excess (ASTPA)(to see Fig.1). The higher the temperature and the inorganic salt concentration(NaBr), the less ratio of upper to lower volume( Vup/Vlow) in ASTP system(to see Table 1～2). Vesicles generally existed in upper and lower phases of ASTP.
The phase behavior diagram has been drawn and analysed in DTAB－SL mixed system and the influences of temperature and inorganic salt upon “aqueous surfactant twophase(ASTP)” have been studied systematically. The results show that ASTP region when cationics is in excess(ASTPC) is larger and stabler than that when anionics is in excess (ASTPA)(to see Fig.1). The higher the temperature and the inorganic salt concentration(NaBr), the less ratio of upper to lower volume( Vup/Vlow) in ASTP system(to see Table 1～2). Vesicles generally existed in upper and lower phases of ASTP.
2001, 17(11): 1031-1035
doi: 10.3866/PKU.WHXB20011114
Abstract:
Ultrasound of frequencey 1.8 MHz,sound intensity 1～5 W•cm－2 were used to induce sonochemical reaction in near field acoustical sonochemical reactor.It was found that the sonochemical yield (expressed by the electro-conductance,the pH value,I2 releasing from KI solution and generation in cavitation water) have linear relation with sound intensity and irradiation time.These results were compared with the sonochemical yield in pulsed ultrasonic field.The cavitational bubble′s amount in cavitational sound field is also presented.
Ultrasound of frequencey 1.8 MHz,sound intensity 1～5 W•cm－2 were used to induce sonochemical reaction in near field acoustical sonochemical reactor.It was found that the sonochemical yield (expressed by the electro-conductance,the pH value,I2 releasing from KI solution and generation in cavitation water) have linear relation with sound intensity and irradiation time.These results were compared with the sonochemical yield in pulsed ultrasonic field.The cavitational bubble′s amount in cavitational sound field is also presented.
2001, 17(11): 1036-1039
doi: 10.3866/PKU.WHXB20011115
Abstract:
The thermal stabilization mechanism of Al2O3 modified by alkaline earths using impregnation method with various contents and calculation time was studied by BET surface area and powder X-ray diffraction.It was found that the addition of alkaline earths increased the surface area of Al2O3 and retarded the transforming into α phase.The stabilization effect was enhanced with the increase of the alkaline earths contents,whereas,the overabundance weakened the stabilization effect.Among the alkaline earths,strontium and calcium are the most effective promoters for inhibiting the reduction of surface area of Al2O3 sintered in air at 1 373K for 10 h.The study of the kinetics behavior of Al2O3 at 1 373K indicated that the stabilization of Al2O3 due to strontium and calcium was mainly attributed to that the alkaline earths played the retarding role of the sintering and α phase transformation within initial 1h during the calcination process.It was the dispersed oxide of alkaline earths but not aluminate that resulted in the stabilization of Al2O3 at high temperature.
The thermal stabilization mechanism of Al2O3 modified by alkaline earths using impregnation method with various contents and calculation time was studied by BET surface area and powder X-ray diffraction.It was found that the addition of alkaline earths increased the surface area of Al2O3 and retarded the transforming into α phase.The stabilization effect was enhanced with the increase of the alkaline earths contents,whereas,the overabundance weakened the stabilization effect.Among the alkaline earths,strontium and calcium are the most effective promoters for inhibiting the reduction of surface area of Al2O3 sintered in air at 1 373K for 10 h.The study of the kinetics behavior of Al2O3 at 1 373K indicated that the stabilization of Al2O3 due to strontium and calcium was mainly attributed to that the alkaline earths played the retarding role of the sintering and α phase transformation within initial 1h during the calcination process.It was the dispersed oxide of alkaline earths but not aluminate that resulted in the stabilization of Al2O3 at high temperature.
2001, 17(11): 1040-1044
doi: 10.3866/PKU.WHXB20011116
Abstract:
The compound that had been crystallographically identified as Na[NiQ2(HQ)](ClO4)(HQ=8-hydroxyqu- inoline) contains no sodium,and instead is [H3O][NiQ2(HQ)](ClO4).The lanthanum-nickel complex [YQ(HQ)2][NiQ3](ClO4) that had been similarly identified contains no yttrium,and its formula is [H3O][Ni2Q3(HQ)3](ClO4)2.The revision of the description of the crystal structures was effected by an examination of the bond dimensions that were derived by calculating the structure factors from the published atomic coordinates.
The compound that had been crystallographically identified as Na[NiQ2(HQ)](ClO4)(HQ=8-hydroxyqu- inoline) contains no sodium,and instead is [H3O][NiQ2(HQ)](ClO4).The lanthanum-nickel complex [YQ(HQ)2][NiQ3](ClO4) that had been similarly identified contains no yttrium,and its formula is [H3O][Ni2Q3(HQ)3](ClO4)2.The revision of the description of the crystal structures was effected by an examination of the bond dimensions that were derived by calculating the structure factors from the published atomic coordinates.
2001, 17(11): 1045-1048
doi: 10.3866/PKU.WHXB20011117
Abstract:
Solubilities and refractive indices of saturated solutions of the system Na2B4O7Na2CO3 NaHCO3NaBO2H2O have been investigated by isothermal method at 25, 35 and 45 ℃. The complex trona (Na2CO3•NaHCO3•2H2O) was found in the system, therefore,there are 5 monosaturated fields,7 disaturated lines and 3 invariant points ：E1t（Na2B4O7•10H2O＋NaBO2•4H2O＋Na2CO3•nH2O）， E2t（Na2B4O7•10H2O＋ Na2CO3•NaHCO3•2H2O＋Na2CO3•nH2O）， E3t（Na2B4O7•10H2O＋Na2CO3•NaHCO3•2H2O＋NaHCO3）， at 25 ℃， n=10； 35 ℃， n=7； 45 ℃， n=1.
Solubilities and refractive indices of saturated solutions of the system Na2B4O7Na2CO3 NaHCO3NaBO2H2O have been investigated by isothermal method at 25, 35 and 45 ℃. The complex trona (Na2CO3•NaHCO3•2H2O) was found in the system, therefore,there are 5 monosaturated fields,7 disaturated lines and 3 invariant points ：E1t（Na2B4O7•10H2O＋NaBO2•4H2O＋Na2CO3•nH2O）， E2t（Na2B4O7•10H2O＋ Na2CO3•NaHCO3•2H2O＋Na2CO3•nH2O）， E3t（Na2B4O7•10H2O＋Na2CO3•NaHCO3•2H2O＋NaHCO3）， at 25 ℃， n=10； 35 ℃， n=7； 45 ℃， n=1.
2001, 17(11): 1049-1052
doi: 10.3866/PKU.WHXB20011118
Abstract:
A series of new derivatives of chitosan——Nalkyl(methyl, ethyl, propyl and butyl) chitosans were synthesized. The degree of substitutions of one of the derivatives Nethyl chitosan were obtained by controlled the molar ratio of the reactants. All of the products show lyotropic liquid crystalline properties regardless of the length of the carbon chains and the degree of substitution. Critical concentration (c) of the samples were measured by polar optical microscopy(POM). The results showed that the value c didn′t varied evidently with the increase of degree of substitution(DS from 0.16～0.82) in the case of a fixed carbon chain, but rise constantly as the length of substituent group varied from methyl to butyl. The result was explained as follow:the introduction of alkyl chain not only broke down some of intermolecular and intramolecular hydrogen bond, but also changed the molecular diameter (d) of chitosan. The former makes the rigidity of molecules weakened, so c of all the derivatives were bigger than chitosan itself. As to the later, d didn′t change with the increase of DS, thus,c didn′t vary with the increase of DS; while,d became bigger as the substituent group varied from methyl to butyl, so c rise accordingly. This rule is in accordance with Onsager and Flory′s theory of the rigid club and was further confirmed by Xray diffraction experiments.
A series of new derivatives of chitosan——Nalkyl(methyl, ethyl, propyl and butyl) chitosans were synthesized. The degree of substitutions of one of the derivatives Nethyl chitosan were obtained by controlled the molar ratio of the reactants. All of the products show lyotropic liquid crystalline properties regardless of the length of the carbon chains and the degree of substitution. Critical concentration (c) of the samples were measured by polar optical microscopy(POM). The results showed that the value c didn′t varied evidently with the increase of degree of substitution(DS from 0.16～0.82) in the case of a fixed carbon chain, but rise constantly as the length of substituent group varied from methyl to butyl. The result was explained as follow:the introduction of alkyl chain not only broke down some of intermolecular and intramolecular hydrogen bond, but also changed the molecular diameter (d) of chitosan. The former makes the rigidity of molecules weakened, so c of all the derivatives were bigger than chitosan itself. As to the later, d didn′t change with the increase of DS, thus,c didn′t vary with the increase of DS; while,d became bigger as the substituent group varied from methyl to butyl, so c rise accordingly. This rule is in accordance with Onsager and Flory′s theory of the rigid club and was further confirmed by Xray diffraction experiments.
2001, 17(11): 1053-1056
doi: 10.3866/PKU.WHXB20011119
Abstract:
Rare-earth elements (La,Ce) have lower standard equilibrium potentials than that of hydrogen and are very difficult to electrodeposite from aqueous solution. Ni-La,Ni-La-P,Ni-Ce,Ni-Ce-P and Ni-P alloys deposits were obtained from aqueous solutions by using optimized electroplaing solutions and process conditions. The experimental results show that these alloys (except Ni-Ce) have amorphous structure. The crystallization kinetics of these amorphous alloy coatings were investigated. The crystallization activation energy and kinetic equation of four kinds of amorphous coatings have been determined by DSC method.The results indicate that the crystallization activation energy of Ni-P,Ni-La,Ni-La-P,Ni-Ce-P amorphous coatings are 200.3,360.8,517.7,420.5 kJ•mol－1 respectively.The crystallization kinetics of the four kinds of amorphous coatings may be expressed by the following equation:
Rare-earth elements (La,Ce) have lower standard equilibrium potentials than that of hydrogen and are very difficult to electrodeposite from aqueous solution. Ni-La,Ni-La-P,Ni-Ce,Ni-Ce-P and Ni-P alloys deposits were obtained from aqueous solutions by using optimized electroplaing solutions and process conditions. The experimental results show that these alloys (except Ni-Ce) have amorphous structure. The crystallization kinetics of these amorphous alloy coatings were investigated. The crystallization activation energy and kinetic equation of four kinds of amorphous coatings have been determined by DSC method.The results indicate that the crystallization activation energy of Ni-P,Ni-La,Ni-La-P,Ni-Ce-P amorphous coatings are 200.3,360.8,517.7,420.5 kJ•mol－1 respectively.The crystallization kinetics of the four kinds of amorphous coatings may be expressed by the following equation:
