EFFECT OF BASE SEQUENCE ON THE ULTRAVIOLET IRRADIATION PRODUCTS OF DOUBLE-STRANDED POLYNUCLEOTIDES CONTAINING BROMOURACIL AND ADENINE

Abstract —The effects of ultraviolet irradiation of double-stranded synthetic polynucleotides containing BrU and A have been investigated. Homopolymer pairs and alternating copolymers composed of either ribo- or deoxyribo-nucleotides were prepared and were irradiated with either 313 nm or ˜ 285 nm light. Strand separation and a modest amount of strand breakage followed irradiation of the homopolymer pairs. Changes in the ultraviolet absorption spectra of the polymers during irradiation reflected the sum of hyperchromic increases caused by progressive strand separation and loss of absorbance caused by photoproduct formation. Extensive debromination occurred. An RNase digest of irradiated poly(rA)–poly¹⁴C(rBrU), analysed by column chromatography, showed components similar to those found previously upon irradiation of single-stranded poly(rBrU). Little photoproduct was released by RNase digestion as mononucleotides. The major photoproduct was in the dinucleotide fraction, and may be 5,5'-diuracil. Base sequence had a profound effect on the sensitivity of the polynucleotides. Irradiation of alternating copolymers with doses of light comparable to those that produced major photochemical changes in the homopolymer pairs brought about little if any change in the copolymers of alternating base sequence.     

Synthesis of195mPt radiolabelled cis-diamminedichloroplatinum/II/ of high chemical and radiochemical purity using high performance liquid chromatography

An improved method is described for the synthesis of^195mPt-radiolabelled cis-diamminedichloroplatinum/II. An amount of 10 mg of 95% enriched¹⁹⁴Pt was irradiated for 75 h in the hydraulic conveyer of the KUR at a thermal neutron flux of approximately 8.15×10¹³ n.cm^–2.sec^–1 and the^195mPt-radiolabelled CDDP was purified using HPLC. The chemical yield is 61% its chemical purity is greater than 99.74% the radiochemical purity is nearly 100%, and the specific activity is 7.4×10⁶ Bq mg^–1 CDDP/200 Ci mg^–1 CDDP/.     

Multivariate comparison of concentration profiles in materials analysis

Hierarchical cluster analysis (HCA) and principal components analysis (PCA) were applied to find groups between similar depth-profiles in thin-layers investigated by Rutherford backscattering spectrometry (RBS).HCA yields in one run an objective hierarchy of similarity for several profiles. Among the similarity coefficients examined the linear measure, the Euclidean distance and the exponential measure respond with different sensitivity to overall shifts in direction of the concentration axis, whereas the correlation measure relates to parallelism of the profiles.For agglomerative HCA with Euclidean distance, a lowest significant linkage level has been defined by use of Fisher'sF-test. For divisive HCA based also on Euclidean distance, the maximum of a separating function marks the most separating cluster step. The outcomes of both proposals agree for the data set investigated.PCA is useful for verifying the results of HCA and yields additional information about the data structure. In the actual example quite different positions of features (concentrations at definite depths) in the space of the two first principal components hint at peculiarities during the metallurgical coating process.     

Numerical simulation of DNA sample preconcentration in microdevice electrophoresis

A numerical model is presented for the accurate and efficient prediction of preconcentration and transport of DNA during sample introduction and injection in microcapillary electrophoresis. The model incorporates conservation laws for the different buffer ions, salt ions, and DNA sample, coupled through a Gaussian electric field to account for the field modifications that cause electromigration. The accuracy and efficiency required to capture the physics associated with such a complex transient problem are realized by the use of the finite element-flux corrected transport (FE-FCT) algorithm in two dimensions. The model has been employed for the prediction of DNA sample preconcentration and transport during electrophoresis in a double-T injector microdevice. To test its validity, the numerical results have been compared with the corresponding experimental data under similar conditions, and excellent agreement has been found. Finally, detailed results from a simulation of DNA sample preconcentration in electrophoretic microdevices are presented using as parameters the electric field strength and the other species concentrations. The effect of the Tris concentration on sample stacking is also investigated. These results demonstrate the great potential offered by the model for future optimization of such microchip devices with respect to significantly enhanced speed and resolution of sample separation.     

Kiesels?urebestimmung durch Destillation von H2SiF6 in einer Silberapparatur

Znsammenfassung Die Arbeit behandelt die Abtrennung der Kieselsäure von TiO₂, Al₂O₃, V₂O₅ und ZrO₂ durch Verflüchtigung von H₂SiF₆ in einer Silberapparatur. Die anschließende photometrische SiO₂-Bestimmung erfolgt nach der Silicomolybdänblaumethode. Es ergibt sich außerdem die Möglichkeit, Kieselsäure von Metallsalzen und von weiteren Oxyden zu trennen, die Fluß- und Schwefelsäure nicht in stärkerem Maße binden.II. Teil der Dissertation von Th. Keil, Gießen 1958. — I. Teil: diese Z. 165, 188, (1959).Wir danken der Titangesellschaft m.b.H., Leverkusen, für das Überlassen der Silberapparatur und überhaupt für das große Interesse, das sie dieser Arbeit entgegengebracht hat.     

A Fortran II Computer Program for Calculation of Concentration-Dependent Sedimentation Coefficients

A computer program for calculation of concentration-dependent sedimentation coefficients is presented. Provision is made for rejection of outlying experimental points. The method yields extremely rapid and precise results from original data without any intermediate steps.