High-speed AFM with a light touch

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HEAVY METALS – VANADIUM IN POULTRY

Os minerais essenciais devem ser fornecidos na dieta em concentrações suficientes para promover uma resposta adequada, e a ingestão de outros minerais e deve ser baixa o suficiente para garantir a total segurança tanto para os animais quanto para a população humana que consumirá a carne e os ovos. Os níveis dietéticos máximos tolerados têm sido gerados, o que pode servir como orientação para garantir a segurança tanto para animais domésticos quanto para humanos. Embora existam várias fontes dietéticas de elementos tóxicos em potencial para aves, programas de controle de qualidade adequados na fábrica de ração, associados com boas práticas de produção e um nutricionista capacitado, devem diminuir consideravelmente a ocorrência de uma contaminação significativa. Lençóis freáticos contaminados por dejetos e outras formas de poluição industrial assim como sistemas uubanos de esgoto representam provavelmente as fontes mais comuns de contaminação nos EUA atualmente. PALAVRAS-CHAVE: minerais, desempenho, toxidcez, nutriçã

INTERACTIONS AMONG THE TRACE MINERALS

Embora existam pelo menos 50 interações conhecidas entre 27 elementos, muitas delas são de pouca importância prática para os criadores. Os animais que consomem dietas completas em sistemas de confinamento não deveriam apresentar problemas metabólicos resultantes de interação entre minerais, exceto em casos de acidentes de suplementação, ou por contaminação ou por erros na mistura dos ingredientes. Os ruminantes sob pastejo estão mais sujeitos aos sinais de intoxicação ou de deficiência, causados por interações entre minerais. Os problemas comuns como a interação do molibdênio, cobre e enxofre são bem conhecidos e apresentam uma extensa documentação em termos de pesquisa. No entanto, o conhecimento de um problema e sua aplicação prática nem sempre são recíprocos. O consumo de quantidades necessárias de um determinado suplemento mineral não pode ser assegurado a todos os indivíduos de um rebanho em pastejo e, conseqüentemente, os problemas advindos de interações são ainda observados em condições de campo. A ênfase corrente na literatura científica sobre produção animal nos Estados Unidos no tocante a interações minerais-traço tem levado em conta o efeito da enzima fitase e o fósforo orgânico na utilização do ferro, zinco e cobre. Experimentos que investigam a interação entre cobre e molibdênio têm sido também relatados nos últimos anos. É provável que, futuramente, a maior parte das pesquisas com minerais esteja direcionada para as funções metabólicas de elementos, com auxílio de técnicas da biologia molecular, em detrimento de ensaios de alimentação com animais. Presume-se que os ensaios simples de alimentação que unicamente avaliam crescimento e conversão alimentar vão se tornar atividades superadas. PALAVRAS-CHAVE: Minerais-traço, alimentação, rebanho

InAs/Ga(1-x)In(x)Sb superlattices for infrared detector applications

The successful growth of InAs/Ga(1-x)In(x)Sb superlattices and their optical and structural characterization is discussed. Samples were grown by molecular beam epitaxy at fairly low substrate temperatures (less than 400 C). Structural quality was assessed by reflection high energy electron difrraction, transmission electron microscopy, and x ray diffraction. Excellent structures were achieved for growth on thick, strain relaxed GaSb buffer layers on GaAs substrates, despite a residual threading dislocation density of 10(exp 9)cm(exp -2) originating at the GaSb/GaAs interface. Despite a lattice mismatch of 1.7 percent, InAs/Ga(0.75)In(0.25)Sb superlattices are observed to be free of misfit dislocations at the thicknesses examined here, owing to the close lattice match between the superlattice and GaSb, which evenly distributes compressive and tensile stresses between the InAs and Ga(0.75)In(0.25)Sb layers. Photoluminescence and photoconductivity measurements indicate that the energy gaps of the strain-layer superlattices are smaller than those of InAs/GaSb superlattices with the same layer thicknesses, and are in agreement with the theoretical predictions of Smith and Mailhiot. Energy gaps of 80 to 250 meV (15 to 5 microns) have been measured for InAs/Ga(0.75)In(0.25)Sb superlattices with 45 to 25 A/25 A layer thickness. Results demonstrate that far-infrared cutoff wavelengths are compatible with the thin superlattice layers required for strong optical absorption in type-II superlattices

Control of experimental uncertainties in filtered Rayleigh scattering measurements

Filtered Rayleigh Scattering is a technique which allows for measurement of velocity, temperature, and pressure in unseeded flows, spatially resolved in 2-dimensions. We present an overview of the major components of a Filtered Rayleigh Scattering system. In particular, we develop and discuss a detailed theoretical model along with associated model parameters and related uncertainties. Based on this model, we then present experimental results for ambient room air and for a Mach 2 free jet, including spatially resolved measurements of velocity, temperature, and pressure

Precision of FLEET Velocimetry Using High-Speed CMOS Camera Systems

Femtosecond laser electronic excitation tagging (FLEET) is an optical measurement technique that permits quantitative velocimetry of unseeded air or nitrogen using a single laser and a single camera. In this paper, we seek to determine the fundamental precision of the FLEET technique using high-speed complementary metal-oxide semiconductor (CMOS) cameras. Also, we compare the performance of several different high-speed CMOS camera systems for acquiring FLEET velocimetry data in air and nitrogen free-jet flows. The precision was defined as the standard deviation of a set of several hundred single-shot velocity measurements. Methods of enhancing the precision of the measurement were explored such as digital binning (similar in concept to on-sensor binning, but done in post-processing), row-wise digital binning of the signal in adjacent pixels and increasing the time delay between successive exposures. These techniques generally improved precision; however, binning provided the greatest improvement to the un-intensified camera systems which had low signal-to-noise ratio. When binning row-wise by 8 pixels (about the thickness of the tagged region) and using an inter-frame delay of 65 microseconds, precisions of 0.5 meters per second in air and 0.2 meters per second in nitrogen were achieved. The camera comparison included a pco.dimax HD, a LaVision Imager scientific CMOS (sCMOS) and a Photron FASTCAM SA-X2, along with a two-stage LaVision HighSpeed IRO intensifier. Excluding the LaVision Imager sCMOS, the cameras were tested with and without intensification and with both short and long inter-frame delays. Use of intensification and longer inter-frame delay generally improved precision. Overall, the Photron FASTCAM SA-X2 exhibited the best performance in terms of greatest precision and highest signal-to-noise ratio primarily because it had the largest pixels

Advances in the Diagnosis of Urothelial Neoplasia

Urothelial neoplasia is a unique cancer in that it consists of a spectrum of tumors with different biologic behaviors. The most common urothelial neoplasm is the low grade superficial papillary carcinoma or papilloma which may recur numerous times but does not result in significant morbidity or mortality. A variant of the superficial papillary carcinoma, which represents approximately 10% of the tumors, is the noninvasive papillary neoplasm which progresses to a less differentiated invasive transitional cell carcinoma (TCC). Considerable effort has been directed at identifying which of the superficial well differentiated papillary tumors will persist, recur and progress to invasive cancer Current approaches to identifying such tumors include cytogenetics, molecular biology, and flow cytometric DNA analysis. In the final group of bladder carcinomas, the high grade invasive neoplasms, evidence suggests that these life-threatening tumors arise de novo without identifiable precursors. Unfortunately, 75% to 90% of invasive TCCs are classified in this group, with the remaining minority progressing from preexisting recurrent superficial papillary carcinomas. Obviously the biologic behavior of these aggressive poorly differentiated tumors is life-threatening, and application of traditional diagnostic procedures and new technologies need to be directed at early diagnosis

Precision of FLEET Velocimetry Using High-speed CMOS Camera Systems

Femtosecond laser electronic excitation tagging (FLEET) is an optical measurement technique that permits quantitative velocimetry of unseeded air or nitrogen using a single laser and a single camera. In this paper, we seek to determine the fundamental precision of the FLEET technique using high-speed complementary metal-oxide semiconductor (CMOS) cameras. Also, we compare the performance of several different high-speed CMOS camera systems for acquiring FLEET velocimetry data in air and nitrogen free-jet flows. The precision was defined as the standard deviation of a set of several hundred single-shot velocity measurements. Methods of enhancing the precision of the measurement were explored such as digital binning (similar in concept to on-sensor binning, but done in post-processing), row-wise digital binning of the signal in adjacent pixels and increasing the time delay between successive exposures. These techniques generally improved precision; however, binning provided the greatest improvement to the un-intensified camera systems which had low signal-to-noise ratio. When binning row-wise by 8 pixels (about the thickness of the tagged region) and using an inter-frame delay of 65 micro sec, precisions of 0.5 m/s in air and 0.2 m/s in nitrogen were achieved. The camera comparison included a pco.dimax HD, a LaVision Imager scientific CMOS (sCMOS) and a Photron FASTCAM SA-X2, along with a two-stage LaVision High Speed IRO intensifier. Excluding the LaVision Imager sCMOS, the cameras were tested with and without intensification and with both short and long inter-frame delays. Use of intensification and longer inter-frame delay generally improved precision. Overall, the Photron FASTCAM SA-X2 exhibited the best performance in terms of greatest precision and highest signal-to-noise ratio primarily because it had the largest pixels