In absence of catalysts, Oscillations in the oxidation of KSCN、Na2S2O3 and SC(NH2)2 by H2O2 are observed in CSTR experiments, single-peak and other phenomena are observed in batch experiments. Oscillations in pH and Pt potential are antiphase in H2O2-Na2S2O3-H+ system and H2O2-KSCN-OH- system, but oscillations in pH and Pt potential are synchronous in H2O2-SC(NH2)2-H+ system.
The solubilities of C60 and C70 in toluene, o-xylene and CS2 between melting point and boiling point have been measured. The temperature-dependent solubillty of C60 displays the anomalous behavior. A solubility maximum of C60 around O℃ for toluene and CS2, and around 30℃ for o-xylene was observed. The temperature-dependent solubility of C70 displays the normal behavior in the same solvents.
△G CS (5) >△G CS (3) >△G CS (4) >△G CS (2)
kCS (2) >kCS (3) >kCS (4) >kCS (5)
其△G CS (4) 与△G CS (3)倒置可按Marcus理论中重排能啬使活化能增加得以解释。
The limiting solubilization amount of aqueous solution of electrolytes, including NaCl, KCl, NaBr, NaI, CaCl2 and Na2SO4 in carbon tetrachloride solution of dodecylammonium propoinate was determined as the added amount of aqueous solution at which turbidity began to be visible. All of the results showed that with increasing concentration of electrolytes, the limiting solubilization amount of aqueous electrolyte solution increased first followed by decreased. This phenomenon could be explained as follows. When electrolyte was present in water pool of reverse micelle, it makes easier for surfactant molecules that surrounding the water pool to migrate to organic phase because of salting-out effect, thus the reverse micelle was expanded. This effect increased with increase of electrolyte concentration. On the other hand, surfactant molecules migrating easier to organic phase implies that the force making surfactant molecules to stick on the surface of water pool became weaker. When electrolyte concentration increased to a certain extent, this force became too weak to keep the reverse micelle, thus the limiting solubilization amount of aqueous solution decreased. According to simplified spherical reverse micelle model, the aggregation number as well as the radii of water pool of reverse micelle have been calculated for aqueous sodium chloride solution of different concentrations. The results support the above explanation.
The photochemical and photophysical behaviors of tri(4-tert-butoxycarbonyl oxyphenyl) sulphonium salts have been investigated. In argon-satureted acetonitrile, the quantum yields of Bronsted acid formed during photolysis of these compounds was abount 0.5. In the transient absorption spectrum excited by 266nm in mathanol and dioxane an evident absorption peak at 360 nm decayed in accordance with pseudo-first-order reaction was observed. In the presence of poly-p-hydroxystyrene or diphenyl sulphide, the apparent second-order reaction decay rate constsnts were 107 and 108 L﹒mo-1﹒s-1, respectively. Results indicated that the transient absorption peak at 360nm was attributed to the diphenyl sulphide radical cations formed in photolysis of sulphonium salts, which were proposed by abstraction of hydrogen from solvent or polymer to yield the photonic acid and diphenyl sulphide as listed in eqns. (1) and (2). The influence of non-nuncleophilic anions of title compounds on their photochemical behavior was just less important.
Relativistic density-functional calculations on free Hg2, Hg4, Hg8, Pb2 and Pb4 clusters, and those clusters embedded in an alkali (A) atom surrounding are reported. Heavy metal-metal (M-M) distances, binding energies and effective charges have been calculated. The Hg-Hg distance in the weakly bound free clusters is over 330 pm. Upon embedding in an alkali surrounding, the bonding is strengthened; the bond lengths are reduced for square planar Hg4 to below 300 pm. The bonding in the hypothetical tetrahedral alkali-mercury cluster appear to be quite different, where Hg4 will undergo a transition to four Hg1. This explains the strict preference of square over the tetrahedral geometry of Hg4 clusters in amalgams. Pb4 is predicted to be stable in a pure cluster and does not show significantly different bonding feature in the lead-alkali crystal. The effective charges on Hg and Pb are calculated to be -0.4 and -0.6, respectively. The bonding characteristics are also examined by calculation of the M4-An interaction energies. The amalgamation energies lie in the range of 50 to 70 kJ/molHg. The formation energy of alkali-Pb is up to 150 kJ/molPb, much stronger than that of alkali-Hg.
Highly oriented Bi4Ti3O12 thin films were prepared by Sol-Gel technique on SrTiO3(100) single crystal, using Bi(NO3)3.5H2O, Ti(OC4H9)4 and CH3COOH as raw materials. The c-axis orientation was about 96%. The effect of pH value of solution on quality of the thin films was studied.
Rules of molten salt phase diagrams of binary system MeX-Me’X4 (Me is monovalent metal, Me’ quadrivalent metal, X halides) were investigated using chemical bond parameter and pattern recognition-artificial neural networks method. Formability of intermediate compounds, chemical stiochiometry, melting type (congruent or incongruent) of intermediate compounds Me2Me’X6 and MeMe’X5 were summarized and predicted, the results were of good reliability.
The rhodium-phosphine complex catalyst Rh(CO)(acac)(PPh3)(Ⅰ) for 1-hexene hydroformylation was studied under the following reaction conditions: CO/H2=1(mole rate), pressure 1.0 MPa, temperature 25-120℃, by using the pressurized in-situ 1H NMR technique. Experimental results indicated that the formation of a rhodium hydride complex from (Ⅰ) began at room temperature and its amount increased with increasing of reaction temperature. This intermediate complex began to decompose at 100℃ and disapeared completely at 120℃. The intensity change of the proton signal was parallel to catalytical activity in hydroformylation of olefins. Under pure CO pressure the proton signal of Ph-H bond was not observed. There was a 0.2 ppm difference in proton chemical shifts of Rh-H bond under pure H2 pressure and under H2+CO pressure. The results showed that the rhodium-hydride carbonyl complex is the active intermediate in the industrial hydroformylation process.
Molar conductances of NaCl and KCl in 0~100%(ω/ω) CH3OH-H2O have been measured by using the alternating conductance bridge method resembling that of Shedlovsky. The results show that the limiting molar conductances (Λ0) of both NaCl and KCl have the lowest curve points around 55%(ω/ω) CH3OH and the limiting molar conductances (Λ0) of KCl are larger than that of NaCl in 0~100%(ω/ω) CH3OH-H2O mixtures, which can be accounted for in terms of the micro-structure and ionic solvated situation of NaCl and KCl aqueous methanol solution. Furthermore, experimental limiting molar conductances (Λ0) for KCl-CH3OH-H2O system in this work are critically compared with that of Amis, which shows that measured results in this work are more reliable.
A new permeability coefficient equation was theoretically derived. It contains both the acid concentration of feed solution and the carrier concentration as well as the acid concentration of stripping solution. The relationship of permeability coefficient and acid concentration of stripping solution was further confirmed by the experimental results of Co2+、Ni2+、 Er3+ ions transporting through the supported liquid membranes.
γ-alumine membranes supported by porous titanium plate were prepared by sol-gel techniqe with alumina isopropoxide. The factors, which influenced membrane per formance, in the membrane preparing process were investigated. A dynamic flow-weighted active pore size distribution apparatus for inorganic membrane were set-up on the basis of Kelvine equation. The results showed that for composite porous membrane the active pore size distribution is about 6-8nm, the most probable pore size is about 7nm and nitrogen permeability is 7.1×10-6mol﹒m-2﹒Pa-1﹒s-2.
We used CD spectroscopy to study the conformations of three cyclic peptides (CP10E: cyclo[Glu(OBz1)-Pro-Gly-Glu(OBzl)-Gly]2, CP10K: cyclo[Lys(Z)-Pro-Gly-Lys(Z)-Gly]2, CP12K: cyclo[Phe-Lys(Z)-Pro-Gly-Lys(Z)-Gly]2 and their correspondent linear peptides (LP10E: Boc-[Glu(OBzl)-Pro-Gly-Glu(OBzl)-Gly]2-OPac, LP10K: Boc-[Lys(Z)-Pro-Lys(Z)-Pro]2-OMe, LP 12K: Bao- [-Lys(Z)-Pro-Gly-Lys(Z)-Gly]2- OMe) in three solvents of different polarity (chloroform, acetonitrile, 2,2,2-triliuroethanol), and it was found that all of linear and cyclicpeptides exists asγ-turn conformation in chloroform, however, in TFE＆ CH3CN solutions, the three linear peptides are inβ Ⅱ-turn conformations. CP10E isβI-turn conformation, CP10K ＆CP12K exists in more than one types of turn conformations. On the basis of our experiments, it was concluded: 1) In the presence of conformational constrained amino acids short linear peptides form obvious secondary structure; 2)The solvent polarity has influence on the peptide conformation and this influence on linear peptides is greater than that on cyclic peptides; 3)The backbone of cyclic peptide has constraint effect on its conformation and makes the secondary structure of cyclic peptide different from that of its relative linear peptide. This information might give some cules in the design of bioactive peptides with different receptor selectivity.
The optimized geometries, energies and harmonic vibrational frequencies of the doublet and quadruplet electronic states of O3- are theoretically predicted at the UHF/631+G*, MCSCF and CISD/MCSCF level. The geometry of the ground has Cs syrnmetry, and bond lengths of 1. 369 and 1.350Å, and a bond angle of 115.7° at the MCSCF level. The excitation energies for transitions 2A2←X2A", 2A’←X 2A" and 2B2← X 2A"I are 2.648, 1.372 and 1 .463 eV, respectively. For the quadruplet states of the ozonide anion the van der Waals complexes only are found. The intra-ionic charge transfers for the X2A", 2A’ and 4∑- states are investigated. The reactions 2A"→2B2→2A",2A’→ 2A1→2A’ and 4∑-→4∑g→4∑- have activation barriers of 1.281, 13.344 and 81.484 kcal﹒mol-1, and rate constants of 3.254×1011 ,4.688×102 and 2.653×10-49 s-1, respectively.
In situ optical emission spectra for an electron assisted hot filament diamond growth process were successfully measured with spatial resolution of better than 1 mm. The emission lines from atomic hydrogen, molecular hydrogen, CH and CH+ radicals were observed in the visible region. Effects of the substrate bias on emission spectra and diamond nucleation were also investigated. It is found that substrate bias can enhance the nucleation density, which may due to the changes of atomic hydrogen concentration and the increase of electron mean temperature.
Polyaniline and its derivatives is one kind of important conductive polymer. In this paper, the active mechanism of substitution and doping on conductivity of polyanilines was studied by means of EHMO-CO method. The result showed that doping and substitution had different active mechanism on conductivity of polyanilines, doping lowered markedly the exciting energy of carrier, while substitution altered chiefly the band width.
The thermograms of Brucalles Br﹒10 and Br﹒981 have been determined. From the thermograms, a thermokinetic equation ln|[(P/Pmax)1-m-1]| =lnb - kt could be established for the limited growth of bacteria. From this equation, the growth constant k, the intial growth rate b, the mean specific growth rate k/m, and the mean thermal power increasing rate Pmaxk/(2m + 2) were calculated. This equation is very significant for the study of bacteria growth and their characteristics.
Formation and structure of liquid crystal in lecithin-water-oleic acid system were studied. It was found that different from the lecithin-water system, there are two types of liquid crystal present. The lamellar liquid crystal was formed at lower content of oleic acid, the values of interlayer spacing are larger than the values in the corresponding liquid crystal without oleic acid. The inverse hexangonal liquid crysta1 was formed at higher content of oleic acid. In lecithin-water-oleic acid(containing 15℅ cholesterol) system the phase behavior of liquid crystal is similar to that in the lecithin-water-oleic acid system. The solubilization rate of solid cholesterol in lamellar liquid crystal of lecithin-water-oleic acid system is more faster than that of lecithin-water system.
The vapor heat capacities of acetic acid, propionic acid, n-butyric acid at various temperatures under atmospheric pressure were measured with a multicomponent vapor flow calorimeter. The results show that the vapor heat capacities of carboxylic acids are much larger than those of the ideal gases at the same temperature and that the vapor heat capacities decrease with increasing temperature. The effect of association in the vapor phase on the vapor heat capacity was studied.
The effect of pH on the adsorption of anionic dye Titan yellow on the activated carbon from aqueous solution has been studied. It has been found that the Zeta potential of the activated carbon has a great effect on adsorption capacity of Titan yellow. The kinetic and the thermodynamic parameters of adsorption as a function of pH has been evaluated. The mechanism for adsorption of anionic dye Titan yellow on the activated carbon has also been discussed.
The photovoltaic features and photo-induced interfacial charge transfer of CuPc-modified Q-CdS films were investigated by surface photovoltage spectra and optical absorption spectra. The results show that the interfacial charge transfer and photosensitization between CuPc and Q-CdS occur under illumination. Based on the observations, the generation and processes of the charge transfer are proposed and discussed.
The activation energies and the reaction orders of the thermal decomposition of three arnmonium molybdates in air were calculated for the first time according to Kissinger method from the DSC curves of their mixture at different heating rates.
Copper oxide cluster ions CunOm n=1-22, m=1-12 are generated by 523 nm laser ablation of CuCO3 solid sample with Time of Flight Mass Spectrometer detection. By changing precursor, we get similar TOF MS from Cu(NO3)2 sample, but narrower mass distribution from CuO sample. We suggest that this is caused by collisionally stabilization. Small gas molecules CO2 and NO2, generated by laser ablation of CuCO3 and Cu(NO3)2, act as buffer gas in supersonic molecular beams, and they are helpful for the production of high mass clusters.