4,906 research outputs found
Novel ionization reagent for the measurement of gas-phase ammonia and amines using a stand-alone atmospheric pressure gas chromatography (APGC) source.
RationaleContaminants present in ambient air or in sampling lines can interfere with the target analysis through overlapping peaks or causing a high background. This study presents a positive outcome from the unexpected presence of N-methyl-2-pyrrolidone, released from a PALL HEPA filter, in the analysis of atmospherically relevant gas-phase amines using chemical ionization mass spectrometry.MethodsGas-phase measurements were performed using a triple quadrupole mass spectrometer equipped with a modified atmospheric pressure gas chromatography (APGC) source which allows sampling of the headspace above pure amine standards. Gas-phase N-methyl-2-pyrrolidone (NMP) emitted from a PALL HEPA filter located in the inlet stream served as the ionizing agent.ResultsThis study demonstrates that some alkylamines efficiently form a [NMP + amine+H]+ cluster with NMP upon chemical ionization at atmospheric pressure. The extent of cluster formation depends largely on the proton affinity of the amine compared with that of NMP. Aromatic amines (aniline, pyridine) and diamines (putrescine) were shown not to form cluster ions with NMP.ConclusionsThe use of NMP as an ionizing agent with stand-alone APGC provided high sensitivity for ammonia and the smaller amines. The main advantages, in addition to sensitivity, are direct sampling into the APGC source and avoiding uptake on sampling lines which can be a significant problem with ammonia and amines
Study of Chromium-Frit-Type Coatings for High-Temperature Protection of Molybdenum
The achievement of more compact and efficient power plants for aircraft is dependent, among other factors, on the perfection of heat-resisting materials that are superior to those in current use. Molybdenum is one of the high-melting metals (melting point, 4750 F). It is fairly abundant and also can be worked into many of the shapes required in modern power plants. To permit its widespread use at elevated temperatures, however, some means must first be found to prevent its rapid oxidation. The application of a protective coating is one method that might be used to achieve this goal. In the present work, a number of chromium-frit-type coatings were studied. These were bonded to molybdenum specimens by firing in controlled atmospheres to temperatures in the range of 2400 to 2700 F
Universally Coupled Massive Gravity
We derive Einstein's equations from a linear theory in flat space-time using
free-field gauge invariance and universal coupling. The gravitational potential
can be either covariant or contravariant and of almost any density weight. We
adapt these results to yield universally coupled massive variants of Einstein's
equations, yielding two one-parameter families of distinct theories with spin 2
and spin 0. The Freund-Maheshwari-Schonberg theory is therefore not the unique
universally coupled massive generalization of Einstein's theory, although it is
privileged in some respects. The theories we derive are a subset of those found
by Ogievetsky and Polubarinov by other means. The question of positive energy,
which continues to be discussed, might be addressed numerically in spherical
symmetry. We briefly comment on the issue of causality with two observable
metrics and the need for gauge freedom and address some criticisms by
Padmanabhan of field derivations of Einstein-like equations along the way.Comment: Introduction notes resemblance between Einstein's discovery process
and later field/spin 2 project; matches journal versio
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"Now all I care about is my future" - supporting the shift: framework for the effective resettlement of young people leaving custody: a summary
This document has been produced as part of the Beyond Youth Custody (BYC) programme, funded under the Big Lottery Fund’s Youth in Focus initiative. BYC has been designed to challenge, advance and promote better thinking in policy and practice for the effective and sustainable resettlement of young people after custody. The programme has published research reports, policy briefings and practitioner guidance on a number of key issues in resettlement including diversity, young people with background trauma, girls and young women, and engaging young people; all resources are available for download at www.beyondyouthcustody.net.
The new framework presented here – which draws on findings from across the programme – proposes, for the first time internationally, a ‘theory of change’ for the sustainable re-entry of young people. This reconceptualisation of resettlement enables a better understanding of why practices previously shown by research to improve recidivism rates are effective. Consequently, the framework provides a new focus for resettlement services’ aims and objectives, and may be particularly useful as a common language for the inter-agency working that we know is essential when supporting young people.
The framework has been designed as a resource for policy makers, decision makers, academics studying youth justice and anyone working with young people leaving custody. A visual representation of the framework outlined in this document can be found on the centre pages. A full version of this report, which includes references and suggestions for further reading, can be found at: www.beyondyouthcustody.net/publications
Building a Web-Features Taxonomy for Structuring Web Design Guidelines
This paper proposes a framework for structuring web design guidelines that incorporates the hierarchies of web features and their semantic relationships with HTML and CSS. It is argued that this approach will be synchronous with the mental model of web designers, thus making the guidelines more usable. In addition, this approach embraces both external and internal aspects of web design, so there is little compromise on the coverage of web design issues. An experiment was conducted to compare the relative effectiveness of the proposed framework with other guideline structures (e.g., principle-oriented and a mixture of principle and feature-oriented). There was evidence that the principle-oriented guidelines performed worse than the other structures, but the analyses failed to establish that the proposed framework as the most effective. The experiment showed promising results but it suffered from small sample size. In spite of this, it is believed that the proposed taxonomy and framework has laid the groundwork for future research.Yeshttps://us.sagepub.com/en-us/nam/manuscript-submission-guideline
Experimental estimation of the luminosity of the Sun
We determine the solar constant experimentally using two independent techniques that allow us to study the dependence of the solar irradiation on the zenith angle and the characteristics of the light extinction in the atmosphere. Our result for the solar luminosity agrees within 7% of the accepted value. This value can be used to estimate the luminosity or power radiated by the Sun. The experiment is inexpensive and conceptually easy to perform and understand.Fil: Gil, Salvador. Universidad Nacional de San MartÃn; Argentina. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de FÃsica; ArgentinaFil: Mayochi, Mariano. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de FÃsica; ArgentinaFil: Pellizza González, Leonardo Javier. Consejo Nacional de Investigaciónes CientÃficas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de AstronomÃa y FÃsica del Espacio. - Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de AstronomÃa y FÃsica del Espacio; Argentin
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