60 research outputs found
PROSET â A Language for Prototyping with Sets
We discuss the prototyping language PROSET(Prototyping with Sets) as a language for experimental and evolutionary prototyping, focusing its attention on algorithm design. Some of PROSETâs features include generative communication, flexible exception handling and the integration of persistence. A discussion of some issues pertaining to the compiler and the programming environment conclude the pape
Surface Hardening Vs. Surface Embrittlement in Carburizing of Porous Steels
Abstract
Carburizing increases the contact fatigue resistance of sintered steels, but the surface hardening may result the formation of surface brittle cracks due to the combined effect of high hardness and porosity. The effect of carburizing on the embrittlement of the case of a 7.3 g/cm3 1.5%Mo - 0.25%C sintered steel was studied. The phenomenon was analyzed theoretically and verified by experiments. The resistance of the carburized steel to surface brittle cracking increases with the load bearing surface and the decrease of the maximum pore size, of the surface microhardness and the friction coefficient. The theoretical analysis was implemented in a design procedure for parts subject to contact stresses
Cytokine profiles of cord and adult blood leukocytes: differences in expression are due to differences in expression and activation of transcription factors
<p>Abstract</p> <p>Background</p> <p>Stem cell transplantation as therapy for hematological disorders is often hampered by severe graft-versus-host-disease. This may be reduced by umbilical cord blood transplantation, an effect that has been attributed to qualitative differences between neonatal and adult T cells. We compared levels of secreted proteins and cytokine mRNA induced in cord blood leukocytes (CBL) and adult blood leukocytes (ABL) by various stimuli.</p> <p>Results</p> <p>While interleukin-2 (IL-2) levels were similar in CBL and ABL, there was less induction of the Th1 cytokine interferon-Îł in CBL. Production of the Th2 cytokines IL-4, IL-5, and IL-13 and the hematopoietic cytokine IL-3 was much lower in CBL versus ABL after T-cell receptor-mediated stimulation, whereas production of GM-CSF was comparable in the 2 cell types. The lower levels of Th1 and Th2 cytokines were maintained in CBL during a 4-day time-course study, while after 12 hours IL-3 and GM-CSF reached in CBL levels similar to those in ABL. For all cytokines except IFNÎł, the IC<sub>50 </sub>values for inhibition by cyclosporin A were similar in ABL and CBL. In contrast, there was less expression and activation of transcription factors in CBL. Activation of NF-ÎșB by TPA/ionomycin was detected in ABL but not CBL. Furthermore, there was less expression of the Th subset-specific transcription factors T-bet and c-maf in CBL versus ABL, whereas GATA-3 expression was similar. Expression of T-bet and c-maf correlated with expression of the Th1 and Th2 cytokines, respectively. Time course experiments revealed that T-bet expression was stimulated in both cell types, whereas c-maf and GATA-3 were induced only in ABL.</p> <p>Conclusion</p> <p>The diminished capability of CBL to synthesize cytokines is probably due to decreased activation of NF-ÎșB, whereas differences in Th subsets are due to differences in regulation of Th lineage-specific transcriptions factors. We propose that the reduced incidence and severity of GvHD after allogeneic transplantation of umbilical CB cells is due to lesser activation of specific transcription factors and a subsequent reduction in production of certain cytokines.</p
Synthesis and study of new nitrogen-containing ligands
Thirty new nitrogen-containing ligands have been synthesised and the coordination chemistry of the majority of these has been investigated. The coordination chemistry of previously reported ligands related to these has also been investigated. The ligands contain a central benzene ring to which nitrogen-containing heterocycles have been appended via one or two linking atoms. In this manner, between two and six such groups have been attached to a benzene ring to give ligands which display a great variety of modes of coordination to transition metals.
These complexes have been characterised by combinations of N.M.R. spectroscopy, mass spectrometry, elemental analysis and X-ray crystallography - the X-ray crystal structures of thirty one complexes have been determined. Among these thirty one structures are chelated and macrocyclic complexes containing monochiral ligands, a supramolecular ten-component cage containing a guest molecule, a new Nâ(arene) mode of coordination, as well as a number of complexes in which arene-arene and metal-arene interactions are observed. Cyclometallated complexes of some of these ligands have also been prepared, the dynamic N.M.R. processes of which have been investigated by variable temperature ÂčH N.M.R. methods
The chemistry of sulfur and nitrogen species in a fog system A multiphase approach
Concentration and phase distribution of sulfur and nitrogen species during a particular fog episode in the Po Valley are experimentally described in this paper. Chemical measurements were carried out simultaneously at different heights within the fog layer, up to 50 m. Microphysical and meteorological parameters necessary for the description of the fog multiphase system were also concurrently measured as a function of height. The fog cycle (formation, evolution, dissipation) is described in terms of the total acidity of a unit volume of air containing gas species, interstitial aerosol particles and fog droplets. The fog system was not closed and input of acidic and basic components was observed during fog evolution. The driving force which determines the acidity of the fog multiphase atmospheric system was found to be the presence of NH 3 and its partitioning among the different phases. A strong decrease of fog water pH (from 5.6 down to 2.8) was observed during fog evolution and was attributed to a HNO 3 input to the system. These acidic and basic inputs are described in terms of a titration/back-titration process of the fog system. The SO 2 oxidation process in fog water was found to be of minor importance in determining the SO 4 = concentration within the fog system, due to both low SO 2 concentration and limited oxidant availability during the experiment. DOI: 10.1034/j.1600-0889.1992.t01-4-00005.
Terrestrial Very-Long-Baseline Atom Interferometry:Workshop Summary
This document presents a summary of the 2023 Terrestrial Very-Long-Baseline Atom Interferometry Workshop hosted by CERN. The workshop brought together experts from around the world to discuss the exciting developments in large-scale atom interferometer (AI) prototypes and their potential for detecting ultralight dark matter and gravitational waves. The primary objective of the workshop was to lay the groundwork for an international TVLBAI proto-collaboration. This collaboration aims to unite researchers from different institutions to strategize and secure funding for terrestrial large-scale AI projects. The ultimate goal is to create a roadmap detailing the design and technology choices for one or more km-scale detectors, which will be operational in the mid-2030s. The key sections of this report present the physics case and technical challenges, together with a comprehensive overview of the discussions at the workshop together with the main conclusions
Konstruktionslehre : Grundlagen erfolgreicher Produktentwicklung ; Methoden und Anwendung
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