Position-sensitive Si pad detectors for electron emission channeling experiments

Position-sensitive detector systems, initially developed for the detection of X-rays, have been adapted for their use in electron emission channeling experiments. Each detection system consists of a 30.8x30.8 mm$^{2}$ 22x22 -pad Si detector, either of 0.3 mm, 0.5 mm or 1 mm thickness, four 128$-$channel preamplifier chips, a backplane trigger circuit, a sampling analog to digital converter, a digital signal processor, and a personal computer for data display and storage. The operational principle of these detection systems is described, and characteristic features such as energy and position resolution and maximum count rate, which have been determined from tests with conversion electrons and $\beta^-\!$ -particles in the energy range 40--600 keV, are presented

Galacto-Oligosaccharides : production, properties, applications, and significance as prebiotics

Galacto-oligosaccharides (GOS) have now been definitely established as prebiotic ingredients after in vitro and animal and human in vivo studies. Currently, GOS are produced by glycoside hydrolases (GH) using lactose as substrate. Converting lactose into GOS by GH results in mixtures containing GOS of different degrees of polymerization (DP), unreacted lactose, and monomeric sugars (glucose and galactose). Recent and future developments in the production of GOS aim at delivering purer and more efficient mixtures. To produce high-GOS-content mixtures, GH should not only have good ability to catalyze the transgalactosylation reaction relative to hydrolysis, but also have low affinity for the GOS formed relative to the affinity for lactose. In this article, several microbial GH, proposed for the synthesis of GOS, are hierarchized according to the referred performance indicators. In addition, strategies for process improvement are discussed. Besides the differences in purity of GOS mixtures, differences in the position of the glycosidic linkages occur, because different enzymes have different regiochemical selectivity. Depending on oligosaccharide composition, GOS products will vary in terms of prebiotic activity, as well as other physiological effects. This review focuses on GOS production from synthesis to purification processes. Physicochemical characteristics, physiological effects, and applications of these prebiotic ingredients are summarized. Regulatory aspects of GOS-containing food products are also highlighted with emphasis on the current process of health claims evaluation in Europe.Agência da Inovação-Progama IDEIA (Portugal)Fundação para a Ciência e a Tecnologia (FCT

The study of methane adsorbed on porous silicon by NMR

Due to the character of the original source materials and the nature of batch digitization, quality control issues may be present in this document. Please report any quality issues you encounter to [email protected], referencing the URI of the item.Bibliography: leaf 44.Not availabl

The study of methane adsorbed on porous silicon by NMR

Due to the character of the original source materials and the nature of batch digitization, quality control issues may be present in this document. Please report any quality issues you encounter to [email protected], referencing the URI of the item.Bibliography: leaf 44.Not availabl

Algumas reflexões para estabelecer a cronologia do "fenômeno transexual" (1910-1995)

O "fenômeno transexual" (Benjamin) é um indicador muito seguro das modificações históricas da percepção científica, mas também cultural e política da identidade sexual no século XX. Para apresentar uma cronologia e uma bibliografia escolhida desse fenômeno, este artigo propõe um fio condutor: a recusa sistemática das interpretações psicanalíticas do transexualismo pelos sexólogos, endocrinologistas e sociólogos que estudaram o problema.<br>The "Transsexual Phenomenon" (Benjamin) is a reliable index of the historical modifications of scientific, cultural and political perception of sexual identity in the 20th century. As an introduction to a chronology and selected bibliography of this phenomenon, I suggest a clue: the systematic denial of the relevance of psychoanalytic explanations of transsexualism by all the biologists, endocrinologists and sociologists who dealt with the problem