Effects of rotation in the laser-pulse photoassociation in a thermal gas of atoms

Photoassociation is a possible route for the formation of chemical bonds. In this process, the binding of colliding atoms can be induced by means of a laser field. Photoassociation has been studied in the ultracold regime and also with temperatures well above millikelvins in the thermal energy domain, which is a situation commonly encountered in the laboratory. A photoassociation mechanism can be envisioned based on the use of infrared pulses to drive a transition from free colliding atoms on the electronic ground state to form a molecule directly on that state. This work takes a step in this direction, investigating the laser-pulse-driven formation of heteronuclear diatomic molecules in a thermal gas of atoms including rotational effects. Based on the assumption of full system controllability, the maximum possible photoassociation yield is deduced. The photoassociation probability is calculated as a function of the laser parameters for different temperatures. Additionally, the photoassociation yield induced by subpicosecond pulses of a priori fixed shape is compared to the maximum possible yield.

TENSILE AND CREEP BEHAVIOR OF GEOSYNTHETICS USING CONFINED-ACCELERATED TESTS

A major aspect in geosynthetics creep analysis is the load level applied to the specimen, usually referred as a percentage of the geosynthetic ultimate tensile strength (UTS). Since both tensile and creep standard tests are performed with in-isolation specimens, they may not reproduce the possibly significant effect of soil-geosynthetic interaction. A new creep testing machine was recently developed and successfully addressed this concern. However, further developments allowed tensile tests to be performed in the same conditions used in nonconventional creep ones. This paper presents the results of nonconventional tensile tests performed with a woven biaxial polyester geogrid. They were used to define its UTS in the same conditions employed in creep tests performed with the new equipment. Despite changes in tensile curves shapes were found, the UTS from confined, accelerated and confined-accelerated tensile tests were quite similar to those obtained with standard tensile test procedure.

Lysine in the diet of Rhamdia voulezi male broodstocks confined in net cages

The focus of this study was to evaluate the effect of lysine on the productive (weight and length gain, apparent feed conversion, specific growth rate and condition factor) and reproductive performance of Rhamdia voulezi males confined in net cages during the first reproductive cycle. The following parameters were assessed: seminal parameters (motility rate and duration, survival, sperm concentration, morphology, pH and osmolarity), hormonal parameters (cortisol and testosterone), testicular tissue (histomorphology), organosomatic indices (gonadosomatic, hepatosomatic and viscerosomatic indices) and composition of essential amino acids, crude protein and moisture of whole carcass. Four hundred fish were used, distributed in a random experimental design with four treatments and four replications in 16 net cages with 25 fish each. The treatments consisted of four different diets prepared so as to contain the following levels of lysine: 1.20, 1.40, 1.60 and 1.80%, with 30% crude protein and 3500 kcal kg(-1) digestible energy for 185 days (Jul./12-Jan./13). Eighteen males were selected per treatment, and they all released semen after slight abdominal pressure. The males were weighed, measured, submitted to hypophysation (2.5 mg kg(-1) carp pituitary extract), and then had their semen and blood collected. The fish were sacrificed by cervical dislocation, dissected, and the testes, liver, fat and guts were removed and weighed. The effects (p < 0.05) for the means of final weight, weight gain, apparent feed conversion and condition factor were observed for the analysis of productive performance. With regard to the reproductive parameters, only the seminal volume was affected (p < 0.05). Thus, the levels of testosterone showed quadratic effect (p < 0.05). The anatomy and the histomorphology of the testes were similar between the treatments during the spermiation period. With regard to the organosomatic indices, there was no influence (p > 0.05) between the treatments. The amino acids in the carcass were not affected (p > 0.05). The increment of lysine in the diet provided linear increase for weight gain and seminal volume and linear decrease for feed conversion in R. voulezi broodstocks confined in net cages. (C) 2014 Elsevier B.V. All rights reserved.

Lipid sources with different fatty acid profile alters the fatty acid profile and quality of beef from confined nellore steers

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)