Laser-induced breakdown in crystalline and amorphous SiO2

The 1.06 μm breakdown thresholds of crystalline and amorphous SiO2were compared. These materials showed dependences of the breakdown threshold on the focal volume which are consistent with a multiphoton-assisted electron avalanche damage mechanism.     

Three-dimensional computer model for simulating realistic solid-state lasers

We developed an accurate and fast three-dimensional computer model for simulating realistic solid-state laser systems. An iteration of the beam propagation calculation was developed to account for the counterpropagation of the laser beams in the saturated gain medium and eventually obtain the converged solution for the output beam. An analytic method was devised to account for the curved cavity mirror and the surface deformation of the gain medium induced by the temperature gradient due to pump absorption. The temperature gradient induced thermal lensing and stress birefringence is also properly included in the model calculation. This model has been validated and shown to be very accurate and efficient for modeling three-dimensional laser systems in a personal computer.     

Results and conclusions from the first pressurized-thermal-shock experiment

The first pressurized-thermal-shock test of a 148 mm thick steel pressure vessel with a 1 m long flaw was performed to investigate fracture behavior of a vessel under conditions relevant to a flawed nuclear reactor pressure vessel during an overcooling accident. The objectives were to observe crack arrest and stability on the ductile upper shelf and the effects of warm prestressing on crack initiation. Three coordinated pressure and thermal transients were imposed on the vessel, which was preheated to 290°C. Two episodes of crack propagation and arrest occurred. The thermal transients were induced by coolant at −29 to 15°C. Pressure transients were as high as 94.4 MPa. The experimental objectives were attained. The inhibiting effects of warm prestressing were definitely demonstrated. Crack propagation was nearly pure cleavage, and arrest at 30 K above the onset of the Charpy upper-shelf was experienced in a positive K₁ gradient and with K₁ = 300 MPa√m. Fracture-mechanics analysis of brittle fracture based on small-specimen toughness measurements was reasonably accurate. Flaw evaluation by procedures of the ASME Boiler and Pressure Vessel Code conservatively predicted vessel failure, which did not occur. No ductile tearing occurred after each crack arrest, although some stable tearing had been predicted on the basis of tearing resistance data.     

Commercial Scale Cucumber Fermentations Brined with Calcium Chloride Instead of Sodium Chloride

Development of low salt cucumber fermentation processes present opportunities to reduce the amount of sodium chloride (NaCl) that reaches fresh water streams from industrial activities. The objective of this research was to translate cucumber fermentation brined with calcium chloride (CaCl₂) instead of NaCl to commercial scale production. Although CaCl₂ brined cucumber fermentations were stable in laboratory experiments, commercial scale trials using 6440 L open‐top tanks rapidly underwent secondary cucumber fermentation. It was understood that a limited air purging routine, use of a starter culture and addition of preservatives to the cover brine aids in achieving the desired complete cucumber fermentation. The modified process was used for subsequent commercial trials using 12490 and 28400 L open‐top tanks packed with variable size cucumbers and from multiple lots, and cover brines containing CaCl₂ and potassium sorbate to equilibrated concentrations of 100 and 6 mM, respectively. Lactobacillus plantarum LA0045 was inoculated to 10⁶ CFU/mL, and air purging was applied for two 2–3 h periods per day for the first 10 d of fermentation and one 2–3 h period per day between days 11 and 14. All fermentations were completed, as evidenced by the full conversion of sugars to lactic acid, decrease in pH to 3.0, and presented microbiological stability for a minimum of 21 d. This CaCl₂ process may be used to produce fermented cucumbers intended to be stored short term in a manner that reduces pollution and waste removal costs.     

The effect of sublethal concentrations of copper and zinc on ventilatory activity. Blood oxygen and pH in rainbow trout (Salmo gairdneri)

Changes in buccal and opercular pressure amplitude, as well as ventilation and coughing frequency were monitored in rainbow trout using catheterization of respiratory cavities and pressure transducers. One or more of the ventilatory parameters measured were found to change under toxicant stress at concentrations of copper or zinc at or below the LC 50. Possible synergistic effects were indicated when the two metal ions were tested together.Serial analyses of arterial P_O2 and pH in fish exposed to copper and zinc individually at concentrations approximating the LC 50 showed that environmental zinc produced a sharp decrease in both P_O2 and pH. Copper, however, caused little effect other than a transient increase in pH. The toxic action of the two metals in low concentrations thus may not be the same.     

High-field magnetoresistance of AuGa

Measurements of the high-field magnetoresistance in AuGa indicate the existence of open orbits in [001]. The nearly free-electron model predicts open orbits in [001] and [100], but evidence for the existence of the latter only begins to appear at the highest fields used in this work.Work supported by the National Science Foundation.     

Effects of verbal and nonverbal reinforcement on the WAIS performance of normal adults.

Explored the effects of verbal reinforcement, nonverbal reinforcement, and no reinforcement by the examiner on the performance of 24 male and 24 female Ss receiving the Wechsler Adult Intelligence Scale. Scores were consistently, though nonsignificantly, higher in the 2 reinforcement conditions than in the no-reinforcement condition. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Flexible infrared waveguides for high-power transmission

This paper gives a comparison of theory with experimental results for the transmission of flexible infrared waveguides fabricated from commercially available aluminum sheet. From this analysis, design equations are generated, which may be used to predict the losses of FIT waveguides in useful geometries.