Effect Of Saturable Absorption On The Behavior Of Spontaneous Emission In Semiconductor Lasers

A substantial reduction of the spontaneous emission intensity is observed at the onset of stimulated emission in some injection lasers. It is shown that this effect is caused by the saturation of optically absorbing traps present in the active region. It is suggested that saturable optical absorption is also responsible for previously unexplained similar reduction observed by Nicoll in bulk semiconductor lasers. © 1973 American Institute of Physics.232949

Effect Of Uniaxial Pressure On The Threshold Current Of Double-heterostructure Gaas Lasers

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)On application of uniaxial pressure perpendicular to the junction, the threshold current of GaAs double-heterostructure injection lasers at room temperature is observed to increase to a certain critical pressure P 0, and then decrease with further increase in pressure. A flip of the polarization of laser light occurs at P 0. This behavior can be explained using a model previously proposed to explain the reduction in threshold of homostructure GaAs lasers upon application of uniaxial pressure. © 1972 The American Institute of Physics.2141241252013/06322-0; FAPESP; São Paulo Research Foundation; FAPESP; São Paulo Research Foundation; 2013/11769-3; FAPESP; São Paulo Research Foundation; 2013/14185-2; FAPESP; São Paulo Research FoundationFundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP

EFFECT OF SATURABLE ABSORPTION ON BEHAVIOR OF SPONTANEOUS EMISSION IN SEMICONDUCTOR LASERS

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Australian consumer attitudes to health claim - food product compatibility for functional foods

This study with Australian consumers investigated how appealing different health claims combined with particular food carriers were to Australian consumers, and compared the results of a similar study with Dutch consumers. 149 shoppers considered up to 30 different food concepts, rating how ‘attractive’, ‘believable’, and ‘new and different’ they found each concept and their ‘intention to try’. Each variable was significantly related to intention to try (p\u3c0.001) and together explained 56% of the intention score. Claims and carriers independently had a significant effect on ratings of attractiveness and intention to try but, unlike the Dutch study, the carrier was a more important predictor of intention to purchase than the claim. Implications for regulation of health claims for food are discussed

SPECTRAL HOLE BURNING IN GAAS JUNCTION LASERS

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Corrosion inhibitors' effect on design service life of RC structures

The implementation of new data regarding the performance of corrosion inhibitors is applied through a performance-based method approved by recent European standards for the probabilistic calculus of service life of reinforced concrete structures. A set of concrete compositions was mixed in order to experimentally obtain strength – compressive – and durability properties – carbonation and chloride diffusion and together with the available results concerning the performance of two types of corrosion inhibitors three scenarios were defined for each concrete composition: (i) plain concrete; (ii) concrete with added admixture inhibitor and (iii) concrete with surface applied migration inhibitor. The probabilistic calculus of service life for each scenario was carried out using modeling equations in which the concrete properties were changed in view of the inhibitors’ performance characteristics. The results show that there is a significant improvement in the design service life when this is modeled considering the effect of corrosion inhibitors

Improved precision on the experimental E0 decay branching ratio of the Hoyle state

Stellar carbon synthesis occurs exclusively via the $3\alpha$ process, in which three $\alpha$ particles fuse to form $^{12}$C in the excited Hoyle state, followed by electromagnetic decay to the ground state. The Hoyle state is above the $\alpha$ threshold, and the rate of stellar carbon production depends on the radiative width of this state. The radiative width cannot be measured directly, and must instead be deduced by combining three separately measured quantities. One of these quantities is the $E0$ decay branching ratio of the Hoyle state, and the current $10$\% uncertainty on the radiative width stems mainly from the uncertainty on this ratio. The $E0$ branching ratio was deduced from a series of pair conversion measurements of the $E0$ and $E2$ transitions depopulating the $0^+_2$ Hoyle state and $2^+_1$ state in $^{12}$C, respectively. The excited states were populated by the $^{12}$C$(p,p^\prime)$ reaction at 10.5 MeV beam energy, and the pairs were detected with the electron-positron pair spectrometer, Super-e, at the Australian National University. The deduced branching ratio required knowledge of the proton population of the two states, as well as the alignment of the $2^+_1$ state in the reaction. For this purpose, proton scattering and $\gamma$-ray angular distribution experiments were also performed. An $E0$ branching ratio of $\Gamma^{E0}_{\pi}/\Gamma=8.2(5)\times10^{-6}$ was deduced in the current work, and an adopted value of $\Gamma^{E0}_{\pi}/\Gamma=7.6(4)\times10^{-6}$ is recommended based on a weighted average of previous literature values and the new result. The new recommended value for the $E0$ branching ratio is about 14% larger than the previous adopted value of $\Gamma^{E0}_{\pi}/\Gamma=6.7(6)\times10^{-6}$, while the uncertainty has been reduced from 9% to 5%.Comment: Accepted for publication as a Regular Article in Phys. Rev. C on July 29 202

ElectrochemicalN-demethylation of tropane alkaloids

A practical, efficient, and selective electrochemicalN-demethylation method of tropane alkaloids to their nortropane derivatives is described. Nortropanes, such as noratropine and norscopolamine, are important intermediates for the semi-synthesis of the medicines ipratropium or oxitropium bromide, respectively. Synthesis was performed in a simple home-made electrochemical batch cell using a porous glassy carbon electrode. The reaction proceeds at room temperature in one step in a mixture of ethanol or methanol and water. The method avoids hazardous oxidizing agents such as H(2)O(2)orm-chloroperbenzoic acid (m-CPBA), toxic solvents such as chloroform, as well as metal-based catalysts. Various key parameters were investigated in electrochemical batch or flow cells, and the optimized conditions were used in batch and flow-cells at gram scale to synthesize noratropine in high yield and purity using a convenient liquid-liquid extraction method without any need for chromatographic purification. Mechanistic studies showed that the electrochemicalN-demethylation proceeds by the formation of an iminium intermediate which is converted by water as the nucleophile. The optimized method was further applied to scopolamine, cocaine, benzatropine, homatropine and tropacocaine, showing that this is a generic way ofN-demethylating tropane alkaloids to synthesize valuable precursors for pharmaceutical products

The transformation of Saperda calcarata (Coleoptera: Cerambycidae) into a cellulose digester through the inclusion of fungal enzymes in its diet

The larvae of the aspen borer, Saperda calcarata , which feed on the inner bark and sapwood of living aspen stems, are unable to digest cellulose. However, they can be transformed into cellulose digesters by adding the active cellulase complex of the fungus, Penicillium funiculosum to their diet. S. calcarata larvae are preadapted to exploit the digestive potential of ingested microbial enzymes. We argue that ingested fungal enzymes may be responsible for cellulose digestion in many, perhaps most or even all, cellulose digesting cerambycid beetles.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/47768/1/442_2004_Article_BF00377333.pd

Long-term follow-up and treatment of congenital alveolar proteinosis

<p>Abstract</p> <p>Background</p> <p>Clinical presentation, diagnosis, management and outcome of molecularly defined congenital pulmonary alveolar proteinosis (PAP) due to mutations in the GM-CSF receptor are not well known.</p> <p>Case presentation</p> <p>A 2 1/2 years old girl was diagnosed as having alveolar proteinosis. Whole lung lavages were performed with a new catheter balloon technique, feasible in small sized airways. Because of some interstitial inflammation in the lung biopsy and to further improve the condition, empirical therapy with systemic steroids and azathioprin, and inhaled and subcutaneous GMCSF, were used. Based on clinical measures, total protein and lipid recovered by whole lung lavages, all these treatments were without benefit. Conversely, severe respiratory viral infections and an invasive aspergillosis with aspergilloma formation occurred. Recently the novel homozygous stop mutation p.Ser25X of the GMCSF receptor alpha chain was identified in the patient. This mutation leads to a lack of functional GMCSF receptor and a reduced response to GMCSF stimulation of CD11b expression of mononuclear cells of the patient. Subsequently a very intense treatment with monthly lavages was initiated, resulting for the first time in complete resolution of partial respiratory insufficiency and a significant improvement of the overall somato-psychosocial condition of the child.</p> <p>Conclusions</p> <p>The long term management from early childhood into young adolescence of severe alveolar proteinosis due to GMCSF receptor deficiency requires a dedicated specialized team to perform technically demanding whole lung lavages and cope with complications.</p