Biological activity and phosphorylation of 2'-azido-2'-deoxyuridine and 2'-azido-2'-deoxycytidine

2'-Azido-2'-deoxyuridine and 2'-azido-2'-deoxycytidine were evaluated for their inhibitory activity against ribonucleotide reductase and for subsequent cell growth inhibition. Their mono- and di-phosphates were synthesized and their inhibitory activities against the reductase were also determined in a permeabilized cell system, along with the two nucleosides. The results of the present study identify the first phosphorylation step involved in the conversion of the two azidonucleosides to the corresponding diphosphates to be rate-limiting in the overall activation.     

Thermodynamic study of BaCuO2 and BaCu2O2

The Gibbs energy changes for the syntheses of the interceramic compounds of BaCuO₂ and BaCu₂O₂ were investigated as a basic study in the Y-Ba-Cu-O system that includes a superconductor, YBa₂Cu₃O_6.5+x . For the compound BaCuO₂, thermogravimetry with CO₂-O₂-N₂ gas mixtures was employed, and equilibrium temperatures were determined at which CO₂ partial pressures in the gas mixtures were equilibrated with mixed powder of BaCuO₂, CuO, and BaCO₃. The Gibbs energy change for the reaction of BaCO₃ + CuO = BaCuO₂ + CO₂ was determined from the relation between CO₂ partial pressure and equilibrium temperature, taking into consideration the effect of CO₂ dissolution in BaCuO₂. For the study on BaCu₂O₂, electromotive force (emf) measurement using yttria-stabilized zirconia solid electrolyte was conducted. A technique using two cells was applied to the emf measurement for minimizing the effect of dispersion of oxygen from samples, and the Gibbs energy change for the reaction of BaCuO₂ + CuO = BaCu₂O₂ + 1/2O₂ was decided from the measured O₂ partial pressure.     

Critical evaluation and optimization of the thermodynamic properties and phase diagrams of the MnO-TiO2, MgO-TiO2, FeO-TiO2, Ti2O3-TiO2, Na2O-TiO2, and K2O-TiO2 systems

All available thermodynamic and phase diagram data have been critically assessed for all phases in the MnO-TiO₂, MgO-TiO₂, FeO-TiO₂, Ti₂O₃-TiO₂, Na₂O-TiO₂, and K₂O-TiO₂ systems at 1 bar pressure from 298 K to above the liquidus temperatures. All reliable thermodynamic and phase diagram data have been simultaneously optimized to obtain, for each system, one set of model equations for the Gibbs energy of the liquid slag as a function of composition and temperature and equations for the Gibbs energies of all compounds as functions of temperature. The modified quasichemical model was used for the molten slag phases.     

Raman spectroscopy of the structures of Li2O-SiO2 and Li2O-GeO2 melts

An analysis of the Li₂O-SiO₂ and Li₂O-GeO₂ systems in the temperature range from 298 to 1373 K has been performed by Raman spectroscopy. A comparison of the spectroscopic data for the crystalline phases, glasses, and melts allowed us to determine the main anion groups existing in these systems and to establish the structural changes induced by changes in the temperature and composition.     

Thermodynamic behavior of phosphorus in CaO-CaF2-SiO2 and CaO-Na2O-SiO2 systems

In order to understand the thermodynamic behavior of phosphorus, such as the polymerization of phosphate ions in slag melts, the influence of phosphorus content of slag melts on the partition of phosphorus between slags and carbon-saturated iron or silver was investigated for the CaO-CaF₂-SiO₂ and CaO-Na₂O-SiO₂ systems at 1573 and 1473 K, respectively. The predominant species changes from PO ₄ ³ to P₂O₇ ^4-approximately at 2 mass pct of phosphorus in slag melts, which is defined as the critical phosphorus content, for the CaO-CaF₂-SiO₂ system which is doubly saturated with CaO and 3CaO · SiO₂. The critical phosphorus content was found to be about 1 mass pct for the CaO-CaF₂-SiO₂ melts saturated with 2CaO · SiO₂. On the other hand, in the case of the 20CaO-35Na₂O-45SiO₂ system, PO₄/^3- is the predominant species until the slag becomes saturated with Ca₃(PO₄)₂. No effect of sulfur on the phosphorus partition ratio was observed for the CaO-CaF₂-SiO₂ system. Formerly Undergraduate Student, Department of Metallurgy, The University of Tokyo.     

CaO-SiO_2-Na_2O-CaF_2-Al_2O_3-MgO保护渣系的Al_2O_3吸收速率和粘度

采用CaO -SiO2 -Na2 O -CaF2 -Al2 O3-MgO渣系 ,通过测定熔渣的粘度和Al2 O3吸收速率 ,研究连铸保护渣的Al2 O3吸收速率与粘度及化学成分之间的关系。在一定条件下 ,当CaO SiO2 为1 .2左右时 ,粘度达到最小值 ,Al2 O3吸收速率达到最大值 ,分别为 0 .1 0Pa·s、8.4 0 3× 1 0 - 4 kg·m- 2 ·s- 1 。随着渣中Na2 CO3含量、CaF2 含量和MgO含量的增加 ,粘度减小 ,Al2 O3吸收速率增大。随着渣中Al2 O3含量的增加 ,粘度增大 ,Al2 O3吸收速率减小。粘度为Al2 O3吸收速率的主要控制因素。随着熔渣粘度的增加 ,连铸保护渣的Al2 O3吸收速率逐渐减小。     

IR spectroscopic characterization of 2-thiohydantoins and 2-thiobarbiturates

A characterization of 2-thiohydantoins and 2-thiobarbiturates by IR spectra is proposed, using three characteristic group frequencies: the "thioureide band" around 1500 cm-1 and the antisymmetric-symmetric stretching modes of NCS bonds around 1400 and 1200 cm-1. The general characteristic absorption areas are found by comparison with N-phenylthioureas and thioanilides.