Phase transitions,structures, and rheological properties of hydroxypropyl cellulose–ethylene glycol and ethyl cellulose–dimethylformamide systems in the presence and in the absence of a magnetic field

Phase transitions, structures, and rheological properties of hydroxypropyl cellulose–ethylene glycol and ethyl cellulose–dimethylformamide systems in the presence and in the absence of a magnetic field have been studied. The application of the magnetic-field results in increases in viscosity and supramolecular particle size in solutions of cellulose ethers. Concentration dependences of viscosity and particle size are described by curves with maxima.     

Preconcentration of radioiodine as AgI and purification from radiotellurium waste

A radiochemical method was investigated for separation and preconcentration of radioiodine from alkaline radiotellurium waste solution as Ag¹²⁵I followed by recovery of ¹²⁵I into aqueous NH₃ solution and final purification by wet distillation. ¹²⁵I–^123mTe radiotracer solution (5 M NaOH) was equilibrated with prepared silver granules for different times and it was found that ¹²⁵I was quantitatively removed from the aqueous phase after 7.0 h. The ¹²⁵I-loaded silver was then equilibrated with ammonia solution in the presence of one of different reducing agents (namely, sodium borohydride, dextrose and zinc dust). Different concentrations of NH₃ solution and reducing agents were studied. Quantitative recovery of ¹²⁵I in the aqueous phase was achieved after 1.0 h of equilibration of ¹²⁵I-loaded silver granules with 2.7M NH₃ solution in the presence of Zn dust with a Zn:Ag molar ratio of 0.5. Purification of the recovered ¹²⁵I was carried out by wet distillation from 20 % H₂SO₄ in the presence of H₂O₂. The distilled off ¹²⁵I was received in a mixture solution of 0.1M NaOH and 0.01M Na₂S₂O₃ with a radionuclidic purity of ≥99.99 %, radiochemical purity of ~98.8 % (as I^? anions) and pH-value of ~13.     

Chemistry of Phosphorus Ylides. Part 37. The Reaction of Phosphonium Ylides with Indoles and Naphthofurans. Synthesis of Phosphanylidenes,Pyrans, Cyclobutenes,and Pyridazine as Antitumor Agents

The reaction of the stabilized phosphonium ylides 2a , 2b with indolinones 1a , 1b and naphthofuranone 13 afforded the corresponding propylidene and ethylidene derivatives 4a , 4b , 4c , 4d and 14a , 14b . On the other hand, the active phosphacumulenes 5a , 5b react with compounds 4a , 4b , 4c , 4d by [4 + 2]‐cycloaddition to give the stable phosphanylidene indole pyranones 6a , 6b , 6c , 6d , 6e , 6f , 6g , 6h . Although compounds 14a , 14b afforded the naphthofuropyrans 16a , 16b , 16c , 16d and triphenylphosphane. Moreover, the phosphallene ylide 7 react with compounds 4a , 4b , 4c , 4d and 14a , 14b to give phosphanylidenecyclobuteneindoline 9a , 9b , 9c , 9d and naphthalenones 18a , 18b , respectively. In addition, the naphthofuropyridazine 21 was obtained from the reaction of the hydrazone 19 and the phosphacumulene 5a . The antitumor activity of some of the new compounds was evaluated, in vitro, against colon and hepatocellular carcinoma cell lines. They showed values closed to that recorded by the reference drug Doxorubicin.     

A two-phase model for laminar film condensation from steam-air mixtures in vertical parallel-plate channels

Detailed results are presented for laminar film condensation from steam-air mixtures flowing downward in vertical flat-plate channels. The mixture flow is laminar and saturation conditions prevail at the inlet. A fully coupled implicit numerical approach is used that achieves excellent convergence behavior, even for high inlet gas mass fractions. The detailed results include velocity, temperature, and gas mass fraction profiles, as well as axial variations of film thickness, pressure gradient and Nusselt number. The effects of a wide range of changes in the four independent variables (the inlet-to-wall temperature difference and the inlet values of gas concentration, Reynolds number, and pressure) on the film thickness, axial pressure gradient, and the local and average Nusselt numbers are carefully examined. It was found that increases in inlet concentration of noncondensable gas caused significant decreases in the film thickness, local Nusselt number, and axial pressure gradient. An analytical solution for the film thickness and velocity field at the end of condensation path was developed and shown to be the asymptotic value of the numerical results for large distances along the channel.     

A two-phase boundary-layer model for laminar mixed-convection condensation with a noncondensable gas on inclined plates

A finite-volume-based numerical model for mixed-convection laminar film condensation from a flowing mixture of a vapor and a heavier noncondensable gas on inclined isothermal flat plates is presented. The full boundary layer equations for the liquid film and the vapor-gas mixtures (including liquid inertia and energy convection terms) are solved implicitly with appropriate liquid-mixture interface conditions. Results were obtained for three mixtures, covering wide ranges of liquid Prandtl number and free-stream gas concentration in the forced-convection, mixed-convection and free-convection flow regimes. The effects of liquid inertia were found to be significant only for low-Prandtl-number fluids and lower gas concentrations. The effects of liquid energy convection were found to be significant only for high-Prandtl-number fluids and to be most significant for mixed-convection condensation. Received on 3 March 1998     

Functionalization of 2-Amino-3-benzyl-6-(benzylthio)pyrimidin-4(3H)-one: An Efficient Access to the Synthesis of Polycyclic Pyrimidine Scaffolds

Russian Journal of General Chemistry - 2-Aminouracil is used in the synthesis of a new series of tri- and tetracyclic pyrimidine scaffolds as the precursor. Thiazolo[5,4-d]triazolo[4,3-a]pyrimidine...     

Dosimetric investigations on radiation-induced Ag nanoparticles in a gel dosimeter

Journal of Radioanalytical and Nuclear Chemistry - Radiation-induced Ag° nanoparticles (NPs) in silver nitrate gel dosimeter incorporating various components was investigated in the dose range...