赖氨酸-Ag反应机理的研究

The interaction of silver(Ⅰ) ion with lysine has been investigated by UV-Vis, fluorescent spectra and electrophoresis method. The effect of pH medium and multicomponent concentration on interaction of lysine-silver has also been studied. Lysine-silver system showed maximum absorbance at 239 nm and 448 nm. Lysine showed fluorescence. The fluorescence excitation wavelength was about 356.6 nm (fluorescence emission wavelength was about 438.6 nm). When the reaction of silver(Ⅰ) ion with lysine happened, fluorescence was quenching. Lysine-silver system carried negative charge, and the electrokinetic potential of double electrode layer was -2.35×10^-4 V.     

Comparison of the Structural Information on Sol-Gel Systems Provided by Pyrene Labeled Fluorescent Probes

The influence of the acid catalyst concentration on the structural evolution of a sol-gel system was studied by doping TEOS based starting solutions with two fluorescent probes: a polystyrene chain (M _n =1700) and a much shorter alkane chain (M=172), both of them labeled at both ends with 1-pyrenyl. For this purpose, each probe was incorporated in two TEOS∶H₂O∶C₂H₅OH mixtures (molar ratios 1∶4∶1), one at pH 1.2 and the other at pH 2.5 (respectively below and above the isoelectric point of silica). Very low concentrations of the probes were used (≤10⁻⁶ M), so the pyrene dimmers and excimers were formed only intramolecularly. The ratios of excimer to monomer fluorescence intensities at excitation wavelength of 360 nm (where mainly the ground state pyrene dimmers are excited) were studied as a function of time. Different evolutions of these ratios were observed, which allowed us to predict that the silica structure developsvia the formation of primary particles, even at pH values below the isoelectric point of silica, where it is not possible to directly detect their formation.     

Dissolution of copper foil in aqueous solution ofpH=2

The specific dissolution rate, expressed in mol cm^–2s^–1, and time-variation of the rest potential of copper foil in an aerated aqueous solution ofpH = 2.0 were measured.

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Die Auflösbarkeit von Kupfer-Folie in wäriger Lösung von pH 2 (Kurze Mitteilung)

Zusammenfassung Es wurde die spezifische Auflösungsgeschwindigkeit (in mol cm^–2s^–1) und die zeitliche Veränderung des Restpotentials von Kupfer-Folie in einer belüfteten wäßrigen Lösung von pH 2,0 gemessen.

     

A multireference configuration interaction method based on the separated electron pair wave functions

A multireference configurational interaction method based on the separated electron pair (SEP) wave functions, SEP‐CI approach, has been developed as an approximation to the traditional CASSCF method. It differs from the CASSCF method in that active orbitals are obtained from the SEP wave function without further optimization in the subsequent CI calculations, and the active space is automatically constructed according to the occupation coefficients of SEP natural orbitals. These features make the present SEP‐CI method computationally much less demanding than the CASSCF method. The applicability of the SEP‐CI method is illustrated with sample calculations on the insertion reaction of BeH₂ and dissociation energies of LiH, BH, FH, H₂O, and N₂. © 2005 Wiley Periodicals, Inc. J Comput Chem 27: 39–47, 2006     

In situ determination of adsorption kinetics of proteins in a finite bath

A method for fast in situ measurement of adsorption kinetics based on a finite bath was developed. We modified the conventional finite bath by replacing the external loop by a dip probe which enables in situ measurement of the concentration change in the contactor. Deposition of adsorbent particles on the reflection surface of the dip probe compromised measurements. Different membranes, a polyamide, a polypropylene and a nylon membrane were tested to protect the internal reflection surface of the dip probe from fouling with adsorbent particles. The nylon membrane provided efficient protection and high mass transfer evaluated by response time experiments. Unspecific adsorption of the model protein on the membrane could also be excluded. To corroborate the measurements of the dip probe the results were compared to a conventional finite bath and to a shallow-bed. The uptake curves for human polyclonal IgG at different concentrationes (0.1-3 g/l) on rProtein A Sepharose FF and MabSelect were used as model system. The effective diffusion coefficients were determined using a pore diffusion model. These values were in good agreement for all methods.     

Study of Structures and Electronic Properties of Pdn–1Pb and Pdn （n≤8） Clusters

Geometric and electronic properties of Pdn–1Pb and Pdn (n≤8) clusters have been studied by using density functional theory with effective core potentials, focusing on the differences between mono- and bimetallic clusters. The average bond length of Pdn–1Pb (n≤8) bimetallic clusters is longer than that of pure palladium clusters except for n = 2 and 3. The most stable structure of Pdn–1Pb (n≤7) is the singlet where there is at least a Pd or Pb atom on its excited state. The energy gaps of Pd–Pb binary clusters are narrower than those of Pdn clusters, and then the chemical activity is strengthened when Pdn clusters are doped with Pb.     

Scaling Function Between the Exponential-6 and the Generalized Lennard-Jones Potential Functions

The van der Waals forces for non-bonded interaction can be expressed either by the Exponential-6 or by the Lennard-Jones(m-n) potential functions, whereby m > n. Hitherto a relationship exists between the Exponential-6 and the Lennard-Jones(12-6) potential functions, with a scaling factor = 13.772 at or near the equilibrium and = 12.0 for long range interaction. This paper attempts to develop relationships between Exponential-6 and a more generalized Lennard-Jones(m-n). Analysis reveals that the relationship exists only when n = 6 and that two sets of scaling factors (as functions of index m) applies for the relationship between Exponential-6 and the Lennard-Jones(m-6), whereby m > 6.     

CO吸附在过渡金属铂表面的微观动力学研究

建立了处理双原子分子-表面相互作用的推广的LEPS势.借助推广的LEPS势,系统研究了一氧化碳分子在铂低指数表面吸附的动力学特性,重现了低指数表面的分子吸附热、吸附几何及本征振动等实验数据；鉴定了某些不合理的文献信息,预测了实验尚未探测到的重要信息:预测到Pt(100)表面四重洞位的C－O伸缩振动频率为1 962.60 cm－1;预测到Pt(110)表面吸附态的C－O及C－Pt键长分别为115.1、147 pm.     

Surface mixed adsorption films of 2,4,6- trimethylphenol–2,4,6-trichlorophenol at aqueous solution/air interface

 The results of experimental studies of the adsorption at the solution/air interface from an aqueous mixture: 2,4,6-trimethylphenol–2,4,6-trichlorophenol are presented. The surface properties of the above-mentioned mixture were studied by surface potential and surface tension measurements. These measurements were carried out as a function of the concentration of 2,4,6-trimethylphenol aqueous solution at a constant concentration of 2,4,6-trichlorophenol. Using the results obtained and based on the Gibbs equation, Helmholtz formula and Motomura’s method the relative surface excesses of adsorbed substances, effective dipole moments, surface molar fractions of solutes and miscibility of adsorbed films were determined. Received: 7 November 1997 Accepted: 26 February 1998     

An algorithm for the calculation of the electrostatic repulsion between surface coated with a charge membrane

We propose a numerical procedure for the calculation of the electrostatic repulsion force between two identical, parallel surfaces immersed in anab electrolyte solution. These surfaces are coated with an ion-penetrable membrane carrying fixed charges. The amount of fixed charges is governed by the dissociation of the functional groups in the membrane phase. The effect of pH on the degree of dissociation of these functional groups is taken into account. The difficulty of extensive use of Jacobi elliptic function in the numerical treatment of Poisson-Boltzmann equation can be circumvented by resorting to the present algorithm.