Oil pricing policy options from the producers' point of view a theoretical approach

Much of what is written about OPEC is from the consumers' point of view. Drs Fixler and Ferrar feel that objectivity requires some analysis from the producers' standpoint. Here they conclude that OPEC's economic self interest will be enhanced by a united pricing and output policy coupled with price discrimination. They reach this conclusion after examining eight possible policy options involving the questions of limited versus unlimited reserves, short-term versus long-term considerations and static versus dynamic analysis.     

Fatigue-resistant silicone elastomer formulations

Fatigue-resistant elastomers have been prepared using various metal oxides as fillers in poly(dimethylsiloxane) (PDMS)-based elastomers. The judicious choice of inorganic fillers produced elastomers that were stable under cyclic testing at elevated temperatures. These experiments were carried out using the Mechanical Energy Resolver, an instrument modified to reduce testing time from approximately 6 weeks to 60 h. Four elastomers showed stable storage moduli, were creep resistant, and showed less than 1% weight loss after 60 h. By comparison, a formulation prepared with alumina as the filler showed high rates of creep and greater than 10% weight loss. © 1998 John Wiley & Sons, Inc. J Appl Polym Sci 70: 1633–1641, 1998     

Wavelength variations of a flashlamp-pumped sodium fluorescein dye laser

The wavelength of a flashlamp-pumped sodium fluorescein dye laser is found to sweep toward decreasing values during each pulse but shifts gradually toward increasing values for successive pulses. Overlap of singlet-state fluorescence and absorption bands, along with chemical changes in the dye, can account for the observed effects.     

Mode-locked flashlamp-pumped coumarin dye laser at 4600 Å

A flashlamp-pumped coumarin dye laser mode-locked by means of intracavity loss modulation has produced subnanosecond, millijoule pulses suitable for pumping other dye lasers or for application to fast photochemical reaction studies.     

Two‐step continuous production of monodisperse colloidal ellipsoids at rates of one gram per day

We report a two‐step process for the continuous production of monodisperse polystyrene colloidal ellipsoids of aspect ratios up to 6.8 at rates that exceed 1.0 g per day, an improvement on previously reported synthetic batch processing rates of nearly a factor of 20. This scale up is accomplished by continuous evaporative processing of a polymer solution into an elastomeric film embedded with colloidal spheres. Subsequently, the film is continuously elongated at a temperature that stretches the embedded spheres into ellipsoids. The method is used to deform initially 1.0 μm diameter spheres into ellipsoids of aspect ratio 1.27 ± 0.15, 3.31 ± 0.44, 3.91 ± 0.72, 4.14 ± 0.47, and 6.77 ± 1.01. The particle production rate reported here opens new possibilities for applications of monodisperse ellipsoids, such as self‐assembly and optical characterization of complex crystalline unit cells, as well as rheological characterization of dilute gels and dense suspensions. © 2017 American Institute of Chemical Engineers AIChE J, 64: 697–707, 2018     

Gas flow effects on selective laser melting (SLM) manufacturing performance

This study has been designed to investigate the effect of inert gas flow within the selective laser melting (SLM) process and the effects induced by this gas flow on the reproducibility of the key attributes (porosity and compression strength) created in the construction of porous titanium components. The work quantifies the characteristics of the manufactured parts and relates results of these characteristics to a predicted gas flow in the build chamber. The results were used to produce design iterations of the gas management system to improve the gas flow distribution in the chamber of a MTT ReaLizer SLM250 machine. Further experiments were then carried out to generate statistical data sets to correlate the flow field quantifying the affect of the redesign on the key measured attributes. Results showed that both the value and the standard deviation of the measured attributes were significantly affected by the improved gas flow, with porosity reducing by 1.7% and the standard deviation of compression strength improving from 12 MPa to 5 MPa. The design modifications have been incorporated into a new machine design to enable the production of porous components of closer control and greater reproducibility.     

Controllable phase-locked frequency splitting in two-frequency lasers

Lasers can be made to oscillate simultaneously at two frequencies by means of anisotropic or nonreciprocal resonator elements. A technique is described for stabilizing the resulting frequency separation by locking it to an external frequency source. The stabilized separation should be useful in optical heterodyne applications.     

Hole-Transporting Silsesquioxanes

The fluorene diol (I) has been chemically incorporated into a sol-gel formulation that was coated to produce a thin overcoat on an organic photoreceptor and cured into a silsesquioxane matrix that efficiently transports holes. The residual potential of the photoreceptor decreased as the amount of hole transport material (I) incorporated into the silsesquioxane matrix was increased. The charge transport was independent of humidity. At 30 wt.% the residual potential is identical to that of a photoreceptor without an overcoat. This methodology produces an organic photoreceptor with a protective overcoat without compromising the electrophotographic characteristics.