A 10-watt CW photodissociation laser with IODO perfluoro-tert-butane

NASA has been investigating the feasibility of direct solar-pumped laser systems for power beaming in space. Among the various gas, liquid, and solid laser systems being proposed as candidates for solar-pumped lasers, the iodine photodissociation gas laser has demonstrated its potential for space application. Of immediate attention is the determination of system requirements and the choice of lasants to improve the system efficiency. The development of an efficient iodine laser depends on the availability of a suitable iodide which has favorable laser kinetics, chemically reversibility, and solar energy utilization. Among the various alkyliodide lasants comparatively tested in a long-pulse system, perfluoro- tert-butyl iodide, T-C4F9I, was found to be the best. However, the operating conditions for the laser medium in a continuously pumped and continuous-flow iodine laser differ considerably from those in the pulsed regime. The results of the continuous wave (CW)) laser performance from t-C4F9I are reported. Perfluoro- n-propyl iodide, n-C3F7I is used for comparison because of its universal use in photodissociation iodine lasers

Laser Doppler velocimetry for continuous flow solar-pumped iodine laser system

A laser Doppler velocimetry (LDV) system was employed to measure the flow velocity profile of iodide vapor inside laser tubes of 36 mm ID and 20 mm ID. The LDV, which was operated in the forward scatter mode used a low power (15 mW) He-Ne laser beam. Velocity ranges from 1 m/s was measured to within one percent accuracy. The flow velocity profile across the laser tube was measured and the intensity of turbulence was determined. The flow of iodide inside the laser tube demonstrated a mixture of both turbulence and laminar flow. The flowmeter used for the laser system previously was calibrated with the LDV and found to be in good agreement

The effect of distractors on starting-delay, missed opportunities and unsafe crossings of children and adults in a simulated pedestrian crossing task

The aims of the research were to investigate the effect of distractors on the pedestrian skills of children and adults. The pedestrian skill of deciding when it is safe to cross a road (decision-making skill) was assessed by a computer-presented simulated pedestrian task. It was predicted that distractors would reduce the performance of all age groups, with the reduction being greater for younger children. The pedestrian skills of Grade 2, Grade 4 and Grade 6 children and adults were assessed in three conditions, without distractors, with on-screen distractors and with off-screen distractors. The results showed that off-road distractors, whether visual or auditory, increased the starting-delay of all age groups. There was no significant difference between off-road-visual and off-road-auditory distractors for any age group except for Grade 6 children. Off-road-auditory distractors increased starting-delay more than off-road-visual distractors for Grade 6 children. Furthermore, off-road and on-road distractors increased the number of missed opportunities for Grade 2 children. On-road distractors increased the number of missed opportunities of Grade 4 and Grade 6 children. The increase was greater for Grade 6 children. The number of unsafe crossings was higher in the condition without distractors. Overall, decision-making skills were vulnerable to distractors. The degree of vulnerability differed depending on age and the specific measures of pedestrian skill

Designing a model of drug quality assurance for Iran

Objective: To take up the project for designing a Drug Quality Assurance Model (GMP) for Iran. Methodology: It is a descriptive and comparative study. GMP models from USA, EU, Australia and Iran, and WHO, ICH and PIC/S were selected for the comparative study. Internet sites and scientific journals were used for data collection. The comparative study determined the primary proposed model. Then, based on Delphi technique, the primary model was evaluated by experts and eventually the final model was designed, for application in Iran. Results: The comparative study and feedbacks of experts determined the final proposed model for pharmaceutical quality assurance (GMP) for Iran, which consisted of two parts. The first part included thirteen chapters consisting sixty-two major titles. The second part consisted of sixteen annexes. Conclusion: Establishment of standards of the final model of GMP in the drug industry could lead to the improvement of quality of national manufactured drugs, hence, promoting the population health levels

Studies of new media radiation induced laser

Various lasants were investigated especially, 2-iodohepafluoropropane (i-C3F7I) for the direct solar pumped lasers. Optical pumping of iodine laser was achieved using a small flashlamp. Using i-C3F7I as a laser gain medium, threshold inversion density, small signal gain, and laser performance at the elevated temperature were measured. The experimental results and analysis are presented. The iodine laser kinetics of the C3F7I and IBr system were numerically simulated. The concept of a direct solar-pumped laser amplifier using (i-C3F7I) as the laser material was evaluated and several kinetic coefficients for i-C3F7I laser system were reexamined. The results are discussed

Dispersant Effects on Zinc Dialkyldithiophosphate (ZDDP) Tribofilm Structure and Composition

For decades, global regulations and government mandates have driven technological developments to improve vehicle fuel economy. Tribological components found in all automotive engines contain metal-on-metal contact zones that may result in increased friction and wear, reducing overall engine efficiency. Lubricant additives such as antiwear and friction modifying components are added to motor oils to prevent some of the damages that may occur at contact zones and improve friction. The effects of other additive components, such as dispersants, that are prevalent in a lubricant additive package on the anti-wear layer remain relatively unknown. Polyisobutenyl Succinimide (PIBSI) dispersants were evaluated for their interactions with the ZDDP antiwear component. The physical and chemical properties and friction of the tribofilms formed in presence of dispersants were defined revealing a previously unknown structure-activity relationship. Further analysis of ZDDP and dispersants revealed surface and bulk fluid interactions