Spray pyrolysis and heat treatment of CuInSe2 for photovoltaic applications

Thin films (about 1 μm) of CuInSe₂ were prepared by spray pyrolysis. The component ratios in the spray solutions and the glass substrate temperature were varied in order to produce films of the desired stoichiometry and the importance of this starting ratio is demonstrated. The optimum spray conditions were suggested by thermodynamical calculations using a free energy minimization computer program applied to the Cu-In-Se system. Optical absorption studies of the films verified the existence of the proper compound.Heat treatments of the films were performed in order to produce conductivities and crystal structures for photovoltaic applications and are discussed in detail. In particular for CuInSe₂ which gives the sphalerite structure under most spray conditions, a short heat treatment of a film with a starting Cu:In:Se ratio of 1.1:1:4 for 10 min at temperatures of 600, 500 and 400°C is described, which produces the chalcopyrite structure.     

The analysis of dental acrylic polymers by pyrolysis-gas chromatography

The vast majority of polymers used in modern prosthetic dentistry are acrylic. They may be homopolymers or copolymers. A technique is described which involves the pyrolysis (thermal degradation) and subsequent analysis by gas chromatography of these polymers. Sample introduction is by means of a ferromagnetic wire which supports a film of the polymer obtained from a solution of the polymer in chloroform. Quantitative determinations can be achieved with the use of relevant standard copolymer compositions.     

SwarmDock and the Use of Normal Modes in Protein-Protein Docking

Here is presented an investigation of the use of normal modes in protein-protein docking, both in theory and in practice. Upper limits of the ability of normal modes to capture the unbound to bound conformational change are calculated on a large test set, with particular focus on the binding interface, the subset of residues from which the binding energy is calculated. Further, the SwarmDock algorithm is presented, to demonstrate that the modelling of conformational change as a linear combination of normal modes is an effective method of modelling flexibility in protein-protein docking.     

Analysis of an altered simple silicate glass using different mineral and glass standards

Quantitative analyses of alteration products formed during the aqueous corrosion of glass were performed using four different sets of standards: relevant mineral standards, an NBS glass standard, unreacted simple silicate glass, and the unreacted center of the reacted glass. A simple silicate glass (containing Na, Mg, Al, Si, and Ca) was reacted in water vapor at 200° C for 14 days. Up to eight alteration phases, including a Mg-rich smectite clay and a zeolite intermediate in composition between Ca-harmotome and phillipsite, formed on the glass surface. A set of energy-dispersed spectra (EDS) of the bulk glass, the clay, and the zeolite were collected from a polished cross-section of the reacted sample. The sum of the elemental weight percents varied by as much as 48% using the different standards. These differences are due to poor electrical conductivity through the clay layer. When the analyses were normalized to 100%, the differences between analyses using the standards were small (less than 10 wt% for individual cations and <5 total wt%). Normalization is inappropriate in the analysis of hydrated alteration phases, which contain a significant amount of water. The inability of the EDS system to detect water requires that absolute analyses be used to estimate the water content of the alteration phases. The bulk glass standard analyses were best suited for this purpose. In addition, use of the bulk glass standard is preferable in our application because spectra of the altered layer and bulk glass can be acquired from the same specimen. Analytical errors that may occur due to poor conductivity through the reacted layer, drifting probe currents, or varying thickness of the carbon coating are also reduce.     

High data rate measurements of droplet dynamics in a vertical gas-liquid annular flow

Two-dimensional phase Doppler anemometry techniques have been used to achieve simultaneous measurement of the velocity and size of individual droplets entrained into the gas core during upward annular gas-liquid flow. Data rates greatly exceeding those of other experimental techniques have been achieved. Information is presented on the centreline variation of droplet velocity and droplet size, together with size and velocity correlations, for a range of flowrates and hydrodynamic development lengths from 135 to 228.