Photocatalytic Properties of Thermally Annealed Films of Titanium Butoxide

Optics and Spectroscopy - We show that titanium dioxide particles capable of reactive oxygen species generation can be produced in titanium butoxide films by annealing them at 500°C. Optimal...     

Effect of the hardened layer thickness of the formation of mesostructures during extension of surface hardened samples

We have made a systematic experimental study of the effect of the thickness of the surface hardened layer in planar samples of 65X13 steel on the geometric parameters of the quasiperiodic mesobustructures which are formed in the surface layer and the bulk of the sample during its plastic extension. The observed dependence of the dimensions of the fragments of mesosubstructure on the thickness of the surface hardened layer correlates well with theoretical calculations [1, 2] of the mechanical or thermal stress at the interface of two media in an external field. Institute of the Physics of Strength and Materials Science, Siberian Section, Russian Academy of Sciences. Tomsk Polytechnic University. Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 6, pp. 63–69, June, 1998.     

The preparation and reactivity of metal-containing monomers. 54. Thermolysis of the acrylamide monomer [Co(CH2=CHCONH2)4(H2O)2](NO3)2

The kinetics and pathways of thermolysis of the Co(II) complex with acrylamide, [Co(CH₂=CHCONH₂)₄(H₂O)₂](NO₃)₂ (1) were studied. The rate of gas evolution is satisfactorily approximated by a first-order equation of autocatalysis. The composition of gaseous and solid products of thermolysis of 1 was studied by IR spectroscopy, mass spectrometry, and electronic microscopy. Thermal transformations of acrylamide complex 1 include three macro stages: dehydration, polymerization of the dehydrated monomer, and thermooxidative destruction of the resulting polymer.     

On the mechanism of soot particle formation

The results of experiments on the isothermic pyrolysis of acetylene, benzene, and diacetylene in a flow reactor near a low-temperature threshold of soot formation are presented. Diacetylene showed a much higher ability to form soot, coke, and tar than the other hydrocarbons. The threshold temperature of soot formation from diacetylene (800 K) was found to be lower than the threshold temperatures for benzene (1230 K) and acetylene (1200 K) for the same pyrolysis time (0.17 s) and equal hydrocarbon concentrations (on the basis of C atoms). The induction periods of soot formation for acetylene and benzene at 1100–1200 K, which were estimated from experiments, correlated well with literature data extrapolated from the high-temperature region. Invisible soot particles (0.3-0.5 Μm) and particles at different steps of carbonization were found among the products of low-temperature pyrolysis. Experimental data were analyzed and compared within the framework of two soot formation theories presented in the literature (the “acetylene” and “aromatic” theories). The contribution of the process of polyyne polymerization in a gas phase to the formation of a soot aerosol is discussed.     

Growth of unusual carbon nanofilaments in methane pyrolysis

Two types of carbon nanofilaments (nanotubes) differing markedly in morphology and growth rate grow on substrate plates containing a supported catalyst in a methane atmosphere at ～1050°C. According to provisional estimates, nanofilaments of one of these types grow at a rate of 5–10 μm/s, which is 50–100 times as high as the growth rate observed for ordinary catalytic filaments (tubes). These filaments are as long as several millimeters, being 50 to 100 nm in diameter. A preliminary examination of their structure has demonstrated that there is no catalyst particle at the filament end and that the filament is likely a carbon-rich polymer. A possible mechanism of the growth of these carbon filaments is discussed.     

A Method for Estimating the Functionality of TiO2/Quantum Dot Multilayer Hybrid Structures Based on the Generation of Reactive Oxygen Species

Optics and Spectroscopy - A new technique for estimating the efficiency of electron transfer from a CdSe/ZnS quantum dot (QD) to TiO2 nanoparticles based on the generation of reactive oxygen...