Search

Zeolite nanosheets can be used for the fabrication of low-defect-density, thin, and oriented zeolite separation membranes. However, methods for manipulating their morphology are limited, hindering progress toward improved performance. We report the direct synthesis (i.e., without using exfoliation, etching, or other top-down processing) of thin, flat MFI nanosheets and demonstrate their use as high-performance membranes for xylene isomer separations. Our MFI nanosheets were synthesized using nanosheet fragments as seeds instead of the previously used MFI nanoparticles. The obtained MFI nanosheets exhibit improved thickness uniformity and are free of rotational and MEL intergrowths as shown by transmission electron microscopy (TEM) imaging. The nanosheets can form well-packed nanosheet coatings. Upon gel-free secondary growth, the obtained zeolite MFI membranes show high separation performance for xylene isomers at elevated temperature (e.g., p -xylene flux up to 1.5 × 10 −3 mol m −2 s −1 and p -/ o -xylene separation factor of ~600 at 250°C).

Pretende-se neste artigo, um ensaio teórico, revisitar a obra de Vilém Flusser, em especial ao que tange ao advento das imagens técnicas, elementos produzidos por recursos proporcionados pelas tecnologias computacionais e da informação. Embora metaforicamente Flusser se refira principalmente à imagem fotográfica, sua abordagem pode muito bem ser aplicada para qualquer tipo de imagem produzida pela mediação técnica, inclusive as imagens digitais feitas por computador. Essas imagens técnicas materializam determinados conceitos a respeito do mundo, exatamente os conceitos que nortearam a construção dos aparelhos que lhes deram forma o que pode servir para uma espécie de “mascaramento da realidade”. Em tempos de pós-verdades, das manipulações textuais e imagéticas amplamente divulgadas pela Internet e até por meios convencionais como a televisão, revisitar o arcabouço teórico que Flusser deixou como herança é de suma importância.

A presente pesquisa tem como objetivo a elaboração de material instrucional para auxiliar os professores do curso de Administração e demais interessados no planejamento, organização e avaliação de visita técnica a empresas. A metodologia da pesquisa caracteriza-se como aplicada, exploratória e descritiva com abordagem predominantemente qualitativa. Quanto aos meios, caracteriza-se como pesquisa bibliográfica e de campo. Inicialmente foram realizadas pesquisas nas bases de dados eletrônicas científicas para o levantamento de publicações de trabalhos de pós-graduação stricto sensu sobre o tema de visita técnica a empresas, especialmente no contexto da educação superior na área de Administração. Foi realizada pesquisa de campo juntos aos professores de uma Instituição de Educação Superior do Sul do Brasil, por meio de um questionário semiestruturado aplicado via online, por meio do recurso Google Forms, devido ao cenário de pandemia provocada pelo Coronavírus SARS-COV-2 (COVID-19). A análise metodológica contou com o aporte teórico da Análise de Conteúdo de Bardin (2016). Os resultados apontam para poucos escritos no âmbito da pós-graduação stricto sensu sobre o tema planejamento, organização e avaliação de visita técnica a empresas. Os achados ainda evidenciaram que a atividade de visita técnica a empresas é realizada por 89% dos professores com a frequência de uma a duas vezes ao ano. Entretanto, 84% dos professores não conhecem material instrucional para o planejamento, organização e avaliação de visita técnica a empresas. Desse modo, ao concluir a pesquisa, apresenta-se como produto final, um guia com orientações sobre o tema. The present research aims to formulate instructional material to assist teachers in the Administration course as well as others interested in planning, organizing, and evaluating technical visits to companies. The research methodology is characterized as applied, exploratory, and descriptive with a predominantly qualitative approach. As for the means, it is characterized as bibliographic and field research. Initially, research was carried out in the electronic scientific databases for the gathering of publications of stricto sensu post-graduate work on the subject of technical visits to companies, especially in the context of higher education in the area of Administration. Field research was carried out with the teachers of a Higher Education Institution in the South of Brazil, by means of a semi-structured questionnaire applied online, through the Google Forms resource, due to the pandemic scenario caused by the Coronavirus SARS-COV-2 (COVID-19). The methodological analysis was supported by the theoretical contributions of Bardin‟s Content Analysis (2016). The results point to few texts written in the stricto sensu post-graduation course on the subject of planning, organization and evaluation of technical visits to companies. The findings also showed that the activity of technical visit to companies is conducted by 89% of the professors once or twice a year. However, 84% of them do not have knowledge of instructional material for planning, organizing and evaluating technical visits to companies. Thus, at the end of the research, a guidebook with directions on the subject is presented as the final product.

Selenium is an essential trace element but is increasingly becoming a contaminant of concern in the electric power industry due to the challenges of removing solubilized selenate anions, particularly in the presence of sulfate. In this work, we evaluate granulated layered double hydroxide (LDH) materials as sorbents for selenium removal from wastewaters obtained from a natural gas power plant with the aim to elucidate the effect of competing ions on the sorption capacities for selenium removal. We first present jar test data, followed by small-scale column testing in 0.43 inch (1.1 cm) and 2 inch (5.08 cm) diameter testbed columns for the treatment of as-obtained cooling tower blowdown waters and plant wastewaters. Finally, we present field results from a pilot-scale study evaluating the LDH media for treatment of cooling tower blowdown water. We find that despite the high levels of total dissolved solids and competing sulfate ions, the selenium oxoanions and other regulated metals such as chromium and arsenic are successfully removed using LDH media without needing any pre-treatment or pH adjustment of the wastewater.

In this Letter we investigate the subleading twist corrections to the photon energy spectrum in the decay Λ b → X s γ and to the lepton energy spectrum in Λ b →X u l ν l . As a first step we rederive the matching coefficients of the subleading twist using a much simpler method. Parametrizing the matrix elements for Λ b and using reparametrization invariance, we show that the energy spectra close to the endpoints are given in terms of only a single universal function.

Das Spektrum der hadronisch invarianten Masse in semileptonischen Zerfällen B → Xclν In der vorliegenden Arbeit wird das Spektrum der hadronisch invarianten Masse des inklusiven semileptonischen Zerfalls B → Xclν präsentiert. Durch die Verwendung der Lichtkegelentwicklung ergibt die Berechnung ein glattes Spektrum, in dem zuverlässig physikalische Schnitte platziert werden können. Diese Entwicklung stellt eine Operatorproduktentwicklung dar, welche der kinematischen Situation, in der die Zerfallsprodukte die maximale Energie erhalten, angepasst ist. Dabei wird berücksichtigt, dass der numerische Wert der invarianten Masse des c-Quarks von der gleichen Größenordnung ist wie der Entwicklungparameter. Der Verlauf des Spektrums wird durch Shapefunktionen beschrieben. Die Resultate stimmen mit publizierten Ergebnissen überein, wenn die Shapefunktionen entwickelt bzw. die Masse des c-Quarks vernachlässigt wird. Durch die genaue Kenntnis des Verlaufs des Spektrums können Momente in Abhängigkeit von einem Cutoff berechnet werden. Ein Vergleich der ersten Momente des gesamten Spektrums mit experimentellen Daten zeigt eine gute Übereinstimmung. Die Ergebnisse dieser Arbeit werden die Ungenauigkeit von hadronischen Parametern verringern, die bei der Bestimmung von CKM-Matrixelementen benötigt werden. Dadurch wird eine präzise Analyse des Unitaritätsdreiecks möglich, die klärt, ob Diskrepanzen zwischen den theoretischen Vorhersagen und den experimentellen Daten existieren und wie die Theorie erweitert werden muss, damit die Effekte der neuen Physik exakt beschrieben werden. Das Spektrum der hadronisch invarianten Masse in semileptonischen Zerfällen B → Xclν The dissertation at hand provides the spectrum of the hadronic invariant mass in the inclusive semileptonic decay B → Xclν. The calculation leading to this result was carried out using the lightcone expansion, which is an operator product expansion that is adjusted to properly describe the kinematics if all decay products reach their maximum energy. This method guaranties a smooth shape for the complete spectrum, which can then be used to introduce physical cuts. Furthermore it was taken into account that the invariant mass of the c quark is of the same order as the expansion parameter. The spectrum is described by shape functions. By expanding these shape functions or by examining the limit mc → 0, known results are reproduced. The knowledge of the exact shape of the spectrum can be used to calculate moments with a cutoff. The first moments in terms of the whole spectrum are in good agreement with experimental data. The results of this work will enhance the precision of hadronic parameters that describe inclusive decays of B mesons. These parameters are used to extract CKM matrix elements from experimental data. A smaller uncertainty concerning these matrix elements will allow for a more accurate analysis of the unitarity triangle which can clarify if there are discrepancies between experimental data and theoretical predictions and how the theory has to be enlarged to incorporate the effects of new physics beyond the standard model.

Arginine-vasopressin (AVP), the antidiuretic hormone, not only regulates water balance but may also exert direct and indirect effects on blood pressure by influencing systemic vascular resistance and body fluid volumes. Recently, specific competitive antagonists of AVP at its vascular and tubular receptors have been described. We used d(CH2)5Tyr(Me) AVP, a vascular (V1) antagonist, and d(CH2)5-D-Tyr(Et) VAVP, a vascular and tubular (V1V2) antagonist, for studies on the role of AVP in deoxycorticosterone acetate (DOCA)-salt hypertension. The antagonists were infused intravenously via osmotic minipumps in unilaterally nephrectomized rats for 6 weeks after the beginning of the DOCA-salt treatment. At the end of the experiment, blood pressure was 15 mm Hg lower in the rats receiving the V1 antagonist than in those in which the vehicle was infused. In the rats receiving the V1V2 antagonist, blood pressure was reduced by 38 mm Hg. However, these rats were in poor general condition and gained no body weight. Their plasma sodium concentration was markedly increased throughout the duration of the experiment. These results suggest that AVP contributes to the development of DOCA-salt hypertension not only through its vascular but also through its renal tubular effects. Thus AVP may act as an impormediator of volume changes associated with alterations in sodium intake or excretion and thereby affect blood pressure.