Effect of Solvent-Induced Coil to Helix Conformational Change on the Two-Photon Absorption Spectrum of Poly(3,6-phenanthrene)

This paper investigates the effect of solvent-induced conformational changes of poly(3,6-phenanthrene) on their two-photon absorption (2PA). Such effect was studied employing the wavelength-tunable femtosecond Z-scan technique and modeled using the sum-over-essential states approach. We observed a strong reduction of the 2PA cross-section when the sample was prepared in hexane (poor solvent) in comparison to chloroform (good solvent), which is related to the conformation adopted by the polymer in each case. In chloroform it adopts a random coil conformation, as opposed to the one-handed helix conformation in hexane. Our results pointed out that the coil to helix conformation change decreases the degree of molecular planarity of the polymer pi-conjugated backbone, which is primarily responsible for their optical nonlinearity, contributing to diminishing the effective transition dipole moments and, consequently, the 2PA cross-section. Moreover, by studying the nonlinear response with different light polarization, we showed that, although the solvent-induced conformational change does not alter the molecular symmetry of the polymer, it modifies considerably the direction of the transition dipole moments between the excited states.

Sequential Methyl-Fluorine Exchange Reactions of Siloxide Ions in the Gas Phase

Air Force Office of Scientific Research (AFOSR)

Design of laminated piezocomposite shell transducers with arbitrary fiber orientation using topology optimization approach

Sensor and actuator based on laminated piezocomposite shells have shown increasing demand in the field of smart structures. The distribution of piezoelectric material within material layers affects the performance of these structures; therefore, its amount, shape, size, placement, and polarization should be simultaneously considered in an optimization problem. In addition, previous works suggest the concept of laminated piezocomposite structure that includes fiber-reinforced composite layer can increase the performance of these piezoelectric transducers; however, the design optimization of these devices has not been fully explored yet. Thus, this work aims the development of a methodology using topology optimization techniques for static design of laminated piezocomposite shell structures by considering the optimization of piezoelectric material and polarization distributions together with the optimization of the fiber angle of the composite orthotropic layers, which is free to assume different values along the same composite layer. The finite element model is based on the laminated piezoelectric shell theory, using the degenerate three-dimensional solid approach and first-order shell theory kinematics that accounts for the transverse shear deformation and rotary inertia effects. The topology optimization formulation is implemented by combining the piezoelectric material with penalization and polarization model and the discrete material optimization, where the design variables describe the amount of piezoelectric material and polarization sign at each finite element, with the fiber angles, respectively. Three different objective functions are formulated for the design of actuators, sensors, and energy harvesters. Results of laminated piezocomposite shell transducers are presented to illustrate the method. Copyright (C) 2012 John Wiley & Sons, Ltd.

Fotogrametria na identificação de assimetrias posturais em cadetes e pilotos da academia da força aérea brasileira

OBJETIVO: Identificar se a atividade de treino de voo pode desencadear alterações posturais em cadetes e pilotos da Academia da Força Aérea Brasileira (AFA). MÉTODOS: Os sujeitos foram avaliados por meio de registro fotográfico em vista anterior e lateral direita, tendo como casuística 80 cadetes da AFA, divididos em quatro grupos, 20 em cada, e 15 pilotos do Esquadrão de Demonstração Aérea (EDA), formando o quinto grupo. As fotos foram transferidas para o Software de Avaliação Postural (SAPO), sendo traçados ângulos relacionados ao alinhamento vertical da cabeça (AVC), alinhamento horizontal da cabeça (AHC), alinhamento horizontal dos acrômios (AHA) e alinhamento horizontal das espinhas ilíacas ântero-superiores (AHE). RESULTADOS: Os resultados mostraram que, após comparação das médias das assimetrias posturais entre os grupos, não houve diferença estatisticamente significante em relação aos ângulos AVC, AHC e AHA. No entanto, na variável AHE, observou-se que o grupo de pilotos apresentou valores significativamente menores que os dos cadetes, sugerindo maior estabilidade postural em relação a essa variável. CONCLUSÃO: O AHE foi a única medida que apresentou diferença estatisticamente significate na comparação entre os pilotos e cadetes dos diferentes anos. Quanto aos demais alinhamentos, não houve diferença, podendo atribuir esse fato aos critérios exigentes de ingresso dos cadetes na AFA e a eficiência do treinamento físico realizado periodicamente.

The aplication of land use and nighttime lights on the development of high-resolution emission inventories for South America

In this paper, nighttime light data are suggested as a proxy for spatial distribution of vehicles running in urban and nearby areas. Nighttime lights focus on human activities, in contrast to traditional Earth observing systems that focus on natural systems. It is the human activity being visible in the form of brightness of nocturnal lights. Two available nighttime lights dataset were used in this work. The first one was provided by the U.S. Air Force Defense Meteorological Satellite Program (DMSP) Operational Linescan System (OLS), henceforth, DMSO-OLS. The second one is the NASA-NOAA Suomi National Polar-orbiting Polar-orbiting Partnership (NPP) satellite, henceforth, Suomi-NPP. To validate the new proposed methodology, hundreds of urban areas of South America were analyzed in a high degree of resolution. The results of this study showed that night-time lights are very well correlated with vehicle fleet, population, and impervious surfaces but with strong spatial variability. The results of this study suggest a better understanding of the human activities in the context of a vehicular-based city conception.

The Amplifier - v. 1, no. 6

In this issue...Lydias, Jack Hunter, U. S. Navy, Student Council, Drama class, Petroleum Engineering, G. I. Bill, Air Force ROTC, General Guthrie, Coach Olsen

The Amplifier - v. 2, no. 1

In this issue...Marcus Daly, Student Council, City Reservoir, Butte, Montana, Leonard Mine, Stanolind Oil Company, Air Force, Margaret Rosencrans

The Amplifier - v. 2, no. 6

In this issue...Butte Civic Center, ROTC program, It Club, Miner's Union Building, Butte, Montana, George Huber, Viola Vestal Coulter Award, Pan American Games

The Amplifier - v. 2, no. 7

In this issue...YMCA, Gardner Denver Scholarship, Civic Center, Butte, Montana, Air Force, Russell Dugdale, Debate team, Anderson Carlisle Society, Student Wives

The Amplifier - v. 2, no. 10

In this issue...American Legion, Spring Sport Carnival, Butte, Montana, Coach Olsen, Butte Civic Center, Arnold Air Society, St. James Hospital, Travonia Mine

The Amplifier - v. 3, no. 4

In this issue...Dr. Van Pelt, Anderson-Carlisle Society, Rose Garden Party, Main Hall, Gordon Parker, Magma Yearbook, Berkley Open Pit, Malmstrom Air Force Base

The Amplifier - v. 3, no. 7

In this issue...M-Day, Library Museum Hall, Junior Prom, Copper Guard, Mineral Club, Ski Club, Bob Wylie, Student Wives Club, Mr. Grover J. Holt, World War I

The Amplifier - v. 4, no. 7

In this issue...Ski Club, Moshe Sheinkin, Dale E. Pickney, Coach Forest 'Frosty' Cox, Air Force, Masquerade Ball, Silver Bow Creek, Butte, Montana

The Amplifier - v. 4, no. 13

In this issue...Wesley Salonen, M-Club, the Anaconda Company, Coach Ed Simonich, Mining Association of Montana, Copper Guards, Engineering Day

The Amplifier - v. 4, no. 14

In this issue...Theta Tau, mining symposium, Mill Buiding, Washoe Theatre, Mineral Club, U.S. Air Force, American Cancer Society, Mt. Con Mine, The Anaconda Company