Titana

Today, with the advancement of nanotechnology, nanomaterials with high atomic number such as gold and titania nanoparticles can be specifically concentrated in tumor cells in various way and benefited from the advantage of increasing the dose due to the proximity of these element next to cancer cells as a radiation sensitizer. In this research, parameters such as radiation energy (in the range of kilo voltage), nanoparticles concentration and tumor depth were investigated in the compressed breast phantom by using the MCNPX code to investigate the effect of radio sensitivity...

Transition-metal alkylidenes have exhibited wide applications in organometallic chemistry and synthetic organic chemistry, however, cyclic Schrock-carbene-like bis-alkylidenes of group 4 metals with a four-electron donor from an alkylidene have not been reported. Herein, the synthesis and characterization of five-membered cyclic bis-alkylidenes of titanium (4 a,b) and zirconium (5 a,b) are reported, as the first well-defined group 4 metallacyclopentatrienes, by two-electron reduction of their corresponding titana- and zirconacyclopentadienes...

The reactions of the Group 4 metallocene alkyne complexes rac-(ebthi)M(η(2) -Me3 SiC2 SiMe3 ) (1 a: M=Ti, 1 b: M=Zr; rac-(ebthi)=rac-1,2-ethylene-1,1'-bis(η(5) -tetrahydroindenyl)) with PhCN were investigated. For 1 a, an unusual nitrile-nitrile coupling to 1-titana-2,5-diazacyclopenta-2,4-diene (2) at ambient temperature was observed. At higher temperature, the CC coupling of two nitriles resulted in the formation of a dinuclear complex with a four-membered diimine bridge (3). The reaction of 1 b with PhCN afforded dinuclear compound 4 and 2,4,6-triphenyltriazine...

Intermolecular hydroamination of heteroatom-substituted allenes with a bulky arylamine was carried out using a bis(amidate) bis(amido) titanium(IV) complex (1) as a precatalyst. The reaction of 2,6-dimethylaniline with oxygen-substituted allene 2c or 2d in the presence of complex 1 gives the ketimine regioisomer as the exclusive product. Reduction of such ketimine products resulted in the formation of amino ethers that were further employed as proligands for the formation of N,O-chelating five-membered titana- and zirconacycles...

Beta particle surface fluxes for tritium, Ni-63, Pm-147, and Sr-90 sources were calculated in this work. High current density was experimentally achieved from Pm-147 oxide in silica-titana glass. A 96 GBq (2.6 Ci) Pm-147 4pi-source with flux efficiency greater than 50% was used for constructing a direct charge capacitor with a polyimide coated collector and vacuum as electrical insulation. The capacitor connected to high resistance (TOmega) loads produced up to 35 kV. Overall conversion efficiency was over 10% (on optimal load)...

In these days a renaissance of metallacycles as an increasingly important class of organometallic compounds for synthetic and catalytic applications is evident, making such very attractive for a plethora of investigations. Titanocene and zirconocene bis(trimethylsilyl)acetylene complexes, regarded as three-membered metallacycles (1-metallacyclopropenes), present a rich chemistry towards unsaturated molecules. By elimination of the alkyne these complexes form by reaction with unsaturated compounds five-membered titana- and zirconacycles, all of which are relevant to stoichiometric and catalytic C-C coupling and cleavage reactions of unsaturated molecules...