The hepatitis B surface antigen manufactured by recombinant DNA technology is extracted from the culture media by density gradient centrifugation using cesium salts. Cesium is considered to be toxic, because it affects active ion transport by blocking potassium channels. The residual trace levels of cesium in hepatitis B vaccine samples are determined by suppressed ion chromatography. Hepatitis B vaccines contain various buffer salts, aluminum-containing adjuvants, proteins and traces of iron. The polyvalent cations (Al3+, Fe3+) and proteins degrade the chromatographic performance in terms of decreased retention time and poor reproducibility. Different sample preparation approaches were evaluated with the aim of eliminating these foulants: (1) filtration, (2) digestion and (3) digestion-protein precipitation. Quantitative elimination of these foulants was achieved in the digestion-protein precipitation sample clean-up approach. Cesium was separated on the IonPac CS17 column with suppressed conductivity detection. The results of the ion chromatography (IC) method were compared with ICP-MS analysis. The precision of determination was better than 6.5% (relative standard deviation) with a method detection limit of 45 ng mL−1. The expanded uncertainty in the measurement at 95% confidence level (coverage factor 2) is better than 16.3%.
The behaviour of attenuation losses in Coplanar waveguides (CPW) is studied for quasi-planar transmission lines with constant characteristic impedance (Z0) and resistivity, having different geometry's. This behavior helps in making a suitable choice of the type of structure and its dimensional parameters depending upon the application. Minimization of loss for a chosen substrate thickness, conductivity and impedance is analyzed. Dispersion characteristics of CPW have been plotted for various metallization thicknesses. A sensitivity analysis for effective dielectric constant with respect to various dimensional parameters of CPW is presented. 相似文献
Dispersion characteristics and wave impedance of trapped coupled image guides are computed by using mode matching techniques. Dispersion curves for trapped coupled image guide are plotted for various dielectric materials and dimensional parameters. The hybrid directional couplers in the above configuration have been theoretically designed by computing the normalization propagation constant. 相似文献
Avalanching of solids is an important multivariable dependent phenomenon that can be a valuable tool for characterization of solids flowability. Although avalanching by itself is primarily chaotic it appears that the fractal analysis of its avalanching mass data can yield very interesting and significant information that is of importance in determining suitability of a material in solids handling and pneumatic transport. 相似文献
The FT-IR and Raman spectra of 3,5-dinitrobenzoic acid (DNBA) have been recorded and analyzed. The equilibrium geometry, various bonding and harmonic vibrational wavenumbers have been calculated with the help of density functional theory (DFT) method. Most of the vibrational modes are observed in the expected range. Mulliken population analysis shows the interactions C-N-O?H-C and C-O?H-C. The most possible interaction is explained using natural bond orbital (NBO) analysis. The strengthening and polarization of the CO bond increases due to the degree of conjugation. HOMO-LUMO energy and the thermodynamic properties are also evaluated. 相似文献
A novel natural product, microphyllone, has been isolated from Ehretia microphylla2 together with baurenol and ursolic acid. Spectroscopic techniques, derivative formation and finally X-ray diffraction have been utilized in the structure elucidation of microphyllone. The structure appears to be 4a, 5, 8,8a - tetrahydro -11,14- dihydroxy-7-methyl-4a-(3-methyl-2-butenyl)-5, 8a-o-benzeno-1, 4-naphthoquinone. 相似文献
The paper presents a radiokinetic study on the appearance and growth of*Fe2S3,*Fe(OH)3,*Fe2(C2O4)3,*Fe(IO3)3 crystals in a colloidal medium of agar and gelatine. The values of the diffusion constants through gels of55+59Fe3+ radioactive cations and of the rate of global growth process of these crystals in agar or gelatine were calculated using
the experimental data. A new method for the determination of the starting time for the complex nucleation process was proposed.
The formation rate of crystals under study decreases in the order:*Fe(OH)3>*Fe(IO3)3>*Fe2S3>*Fe2(C2O4)3, in agar medium and*Fe(OH)3>*Fe(IO3)3>*FeC2O4)3>*FeS3, in gelatine medium. 相似文献