Solubility of carbon dioxide in aqueous solutions of sodium chloride: Experimental results and correlation

The solubility of carbon dioxide in aqueous solutions of sodium chloride was measured in the temperature range from 40 to 160°C, up to 6 mol-kg salt solutions and total pressures up to 10 MPa. Pitzer's⁽¹⁾ equations as well as the Chen and Evans⁽²⁾ model were used to correlate the new data. Results are reported and compared to literature data and correlations.     

Effect of post-metallization annealing on the ferroelectric properties of sol-gel derived PZT thin films

A series of monolithic Pt-PZT-Pt capacitors was prepared based on sol-gel derived PZT 53/47 films fired to 700 C. After deposition of top Pt electrodes, the capacitors were subjected to post-metallization annealing (PMA) temperatures of 100 C to 700 C. Dielectric and ferroelectric (FE) characterizations were performed. Increasing the PMA temperature produced lower values of spontaneous and remanent polarizations, dielectric constant and leakage currents. The observations are correlated with a proposed FE capacitor model.     

Interaction of carbon dioxide with ditoluenetitanium

The interaction of ditoluenetitanium with CO{in2} has been studied. Based on hydrolysis, thermolysis, and IR spectral data, the conclusion is drawn that a low-valent titanium oxalate is formed.This study was financially supported by the Russian Foundation for Basic Research (Project No. 93-03-5538).Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 12, pp. 2241–2242, December, 1994.     

Nanocrystalline ceramic films for efficient conversion of light into electricity

Transparent nanocrystalline films of oxide semiconductors such as TiO₂ and Fe₂O₃ have been prepared on a conducting glass support employing a sol-gel procedure. The films are composed of nanometer-sized particles sintered together to allow for percolative charge carrier transport. The internal surface of these films is very high, roughness factors of the order of 1000 being readily obtained. Electric polarization was applied for forward and reverse biasing of the films and the resulting optical changes have been analyzed to derive their flat band potential. Band gap excitation of such nanocrystalline semiconductors produces electron-hole pairs which migrate through the film to be collected as electric current. Steady state photolysis and time resolved laser techniques have been applied to scrutinize the mechanism of light induced charge separation within the nanostructure. When derivatized with a suitable chromophore, TiO₂ films give extraordinary efficiencies for the conversion of incident photons into electric current, exceeding 90% for certain transition metal complexes within the wavelength range of their absorption band. The underlying physical principles of these astonishing findings will be discussed. Exploiting this discovery, we have developed a new type of photovoltaic device whose overall light to electric energy conversion yield is 10% under simulated AM 1.5 solar radiation.     

High temperature superconducting thin films for microwave filters

YBa₂Cu₃O_7-δ and Tl₂Ba₂CaCu₂O₈ thin films for microwave filters were synthesized by pulsed laser deposition and the two-step thalliation process. Substrate quality requirements and the relation of thin film morphology, microstructure with microwave surface resistance were discussed.     

Evolution of stress and strain relaxation of Ge and SiGe alloy films on Si(0 0 1)

The growth of Ge and SiGe alloy films on Si substrates has attracted considerable interest in the last years because of their importance for optoelectronic devices as well as Si-based high speed transistors. Here we give a short overview on our recent real time stress measurements of Ge and SiGe alloy films on Si(0 0 1) performed with a sensitive cantilever beam technique and accompanied by structural investigations with atomic force microscopy. Characteristic features in the stress curves provide detailed insight into the development and relief of the misfit strain. For the Stranski–Krastanow system Ge/Si(0 0 1) as well as for SiGe films with Si contents below 20%, the strain relaxation proceeds mainly into two steps: (i) by the formation of 3D islands on top of the Ge wetting layer; (ii) via misfit dislocations in larger 3D islands and upon their percolation.     

Titanium carbonitride films on cemented carbide cutting tool prepared by pulsed high energy density plasma

Hard films prepared by pulsed high energy density plasma (PHEDP) are characterized by high film/substrate adhesive strength, and high wear resistance. Titanium carbonitride (TiCN) films were deposited onto YG11C (ISO G20) cemented carbide cutting tool substrates by PHEDP at room temperature. XRD, XPS, SEM, AES, etc. were adopted to analyze the phases (elements) composition, microstructure and the interface of the films, respectively. The results show that, the uniform dense films are composed of grains ranging from 70 to 90 nm. According to the AES result, there is a broad transition layer between the film and the substrate, due to the ion implantation effect of the PHEDP. The transition layer is favorable for the film/substrate adhesion.     

X-ray photoelectron spectroscopy characterization of composite TiO2–poly(vinylidenefluoride) films synthesised for applications in pesticide photocatalytic degradation

X-ray photoelectron spectroscopy (XPS) was adopted for the analytical characterization of composite titanium dioxide–poly(vinylidenefluoride) (TiO₂–PVDF) films developed for applications in the photocatalytic degradation of pollutants.

The composites were deposited on glass substrates by casting or spin coating from TiO₂–PVDF suspensions in dimethylformamide (DMF). XPS data on the TiO₂–PVDF surface composition were used to optimize preparation conditions (composition of the TiO₂/PVDF suspension, deposition technique) in terms of titanium dioxide surface amount and film stability.

The use of spin-coating deposition and the increase of TiO₂ amount in the DMF suspensions were found to improve the titanium surface content, although high TiO₂/PVDF ratios led to film instability. PVDF–TiO₂ films were also used in preliminary photocatalytic degradation tests on isoproturon, a phenylurea herbicide, under solar UV irradiation; the results were compared to direct photolysis to evaluate the catalytic efficiency of immobilized TiO₂ and the role played by the PVDF film during the degradation process.     

Dialdehyde starch‐crosslinked chitosan films and their antimicrobial effects

For improved mechanical and water‐swelling properties of chitosan films, a series of transparent films were prepared with dialdehyde starch as a crosslinking agent. Fourier transform infrared and X‐ray analysis results demonstrated that the formation of Schiff's base disturbed the crystallization of chitosan. The mechanical properties and water‐swelling properties of the films were significantly improved. The best values of the tensile strength and breaking elongation were 113.1 MPa and 27.0%, respectively, when the dialdehyde starch content was 5%. All the crosslinked films still retained obvious antimicrobial effects toward S. aureus and E. coli, and they showed potential for biomedical applications. © 2003 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 41: 993–997, 2003     

Coupled lubrication and Stokes flow finite elements

A method is developed for performing a local reduction of the governing physics for fluid problems with domains that contain a combination of narrow and non‐narrow regions, and the computational accuracy and performance of the method are measured. In the narrow regions of the domain, where the fluid is assumed to have no inertia and the domain height and curvature are assumed small, lubrication, or Reynolds, theory is used locally to reduce the two‐dimensional Navier–Stokes equations to the one‐dimensional Reynolds equation while retaining a high degree of accuracy in the overall solution. The Reynolds equation is coupled to the governing momentum and mass equations of the non‐narrow region with boundary conditions on the mass and momentum flux. The localized reduction technique, termed ‘stitching,’ is demonstrated on Stokes flow for various geometries of the hydrodynamic journal bearing—a non‐trivial test problem for which a known analytical solution is available. The computational advantage of the coupled Stokes–Reynolds method is illustrated on an industrially applicable fully‐flooded deformable‐roll coating example. The examples in this paper are limited to two‐dimensional Stokes flow, but extension to three‐dimensional and Navier–Stokes flow is possible. Copyright © 2003 John Wiley & Sons, Ltd.