Laser destruction of photosensitized superficial malignant tumours

After intraperitoneal administration the photosensitizing dye acridine orange localized to malignant mouse tumours. Subsequent irradiation with a cw argon laser, at energy levels that did not cause heat damage, produced destruction of these tumours. In nine out of ten mice there was no evidence of regrowth after four months.     

Adsorption of cadmium on anatase nanoparticles-effect of crystal size and pH

The adsorption and desorption of Cd(2+) to large and nanometer-scale anatase crystals have been studied to determine the relationship between heavy metal adsorption properties and anatase particle size. A solvothermal method was used to synthesize very fine anatase nanocrystals with average grain sizes ranging from 8 to 20 nm. On a surface area basis, it was found that large and nanometer-scale anatase particles had similar maximum Cd(2+) adsorption capacities, while their adsorption slopes differed by more than 1 order of magnitude. The particle-size effect on adsorption is constant over a pH range of 4-7.5. The desorption of Cd(2+) from both particle sizes is completely reversible. The adsorption data have been modeled by the Basic Stern model using three monodentate surface complexes. It is proposed that intraparticle electrostatic repulsion may reduce the adsorption free energy significantly for nanometer-sized particles.     

Adsorption and precipitation of an aminoalkylphosphonate onto calcite

The mechanism of nitrilotris(methylenephosphonic acid) (H6NTMP)/calcite reaction was studied with a large number of batch experiments where phosphonic acid was neutralized with 0 to 5 equivalents of NaOH per phosphonic acid and the concentration ranged from about 10 nmol/L to 1 mol/L. It is proposed that the phosphonate/calcite reactions are characterized in three steps. At low phosphonate concentration (<1 micromol/L NTMP concentration), the phosphonate/calcite reaction can be characterized as a Langmuir isotherm. At saturation, only approximately 7% of the calcite surface is covered with phosphonate; presumably these are the kinks, step edges, or other imperfect sites. At higher phosphonate concentrations, the attachment is characterized by calcium phosphonate crystal growth to a maximum of four to five surface layer thick, with solid phase stoichiometry of Ca(2.5)HNTMP and a constant solubility product of 10(-24.11). After multiple layers of phosphonate are formed on the calcite surface, the solution is no longer at equilibrium with calcite. Further phosphonate retention is probably due to mixed calcium phosphonate solid phase formation at lower pH and depleted solution phase Ca conditions. The proposed mechanism is consistent with phosphate/calcite reaction and can be used to explain the fate of phosphonate in brines from oil producing wells and the results are compared with two oil wells.     

Synthesis of Novel Saccharide Hydrazones

Synthesis of important heterocyclic hydrazine derivatives N-aminopyrrolidine, N-aminopiperidine, and N-aminoazepane from hydrazine hydrate and dihalogenides were examined and optimized. These heterocyclic hydrazine derivatives were used in condensation reactions with six different monosaccharides to form corresponding hydrazones. Biological evaluations of these novel compounds, which are simple acyclic nucleoside analogs, were done. L-Arabinose N-aminoazepane hydrazone showed minor anti-HIV activity, giving a starting point for further structural modifications.     

[(TMEDA)Co(NO)2][BPh4]: A versatile synthetic entry point to four and five coordinate {Co(NO)2} complexes

[(TMEDA)Co(NO)₂][BPh₄] reacts with Group 1 salts of various monoanionic ligands to yield four and five coordinate {Co(NO)₂}¹⁰ complexes. The synthesis of the four coordinate complex of the form [{LX}Co(NO)₂] via salt-metathesis reactions of [(TMEDA)Co(NO)₂][BPh₄] with [{ArNC(Me)CHC(Me)NAr}Li(OEt₂)] (Ar = 2,6-di-iso-propylphenyl) is reported. In addition [(TMEDA)Co(NO)₂][BPh₄] reacts with either KTp^∗ or a suite of cyclopentadienyllithium and cyclopentadienylsodium reagents, to generate the corresponding five coordinate [{L₂X}Co(NO)₂] complexes ({L₂X = C₅H₅, MeC₅H₄, Cp^∗, ^tBuC₅H₄, Ph₂CHC₅H₄, Me₃SiC₅H₄, ^tBuMe₂SiC₅H₄, ⁱPr₃SiC₅H₄, 1,3-(ⁱPr₃Si)₂C₅H₃ and Tp^∗). In support of existing precedent, the four coordinate complex is a thermally robust and readily isolable species while five coordinate complexes are thermally unstable transient intermediates that may either undergo dissociation of an NO ligand or be trapped by alkenes to form the corresponding metal dinitrosoalkane complexes. These reactions demonstrate that [(TMEDA)Co(NO)₂][BPh₄] provides a versatile synthetic entry point to cobalt dinitrosyl complexes and obviates the need for the repeated use of nitric oxide in the preparation of dinitrosoalkane complexes of cobalt.     

Investigation of the aerodynamic properties and flow field around hypervelocity objects in a ballistic test range

The equipment of a ballistic test range for research on hypersonic motion and flow around typical models of explosion-propelled projectiles. A method for obtaining instantaneous interferograms of the flow around an object and a procedure for calculating the radial density distributions from measurements made on them are briefly set forth. The values of the aerodynamic drag at zero angle of attack are obtained for three models in trajectory experiments, and a comparative assessment of their stability is made. The principles for performing numerical aerodynamic calculations of hypervelocity flow around objects typically having a compound shape are formulated. Zh. Tekh. Fiz. 69, 6–11 (December 1999)