Zur Rolle von EDA-Komplexen bei kationischen Polymerisationen. VIII. Zur Charge-Transfer-Wechselwirkung von bπ-Donatoren mit organischen Kationen in Lösung

On the Role of EDA-complexes in Cationic Polymerization. VIII. The Charge-Transfer-Interaction of bπ-Donors with Organic Cations in Solution The interaction of 25 aromatic bπ-donors with organic cations of the type (RC₆H₄)₃ C^⊕X^⊖ (R =  CH₃,  C(CH₃)₃,  OCH₃,  H,  Cl,  I,  NO₂; X = BF₄^⊖, AsF₆^⊖, SbCl₆^⊖, FeCl₄^⊖) is investigated by means of u.v.-spectroscopy. The influence of the dissociation on the charge transfer energy will be discussed. With the decreasing concentration of the salt the charge transfer band is hardly shifted at longer wave length. The charge transfer energy can be described as a linear function of structural parameters (i.e. σ_p of R; I_p of the donor and reciprocal radius of the anions, respectively). The influence of the solvent is dependent on both the donicity and dielectric factors.     

Flow behavior of concentrated solutions of an SBS block copolymer

The non-Newtonian viscosity of concentrated solutions of a styrene-butadiene-styrene, SBS, block copolymer was measured with a novel capillary viscometer. Polymer concentrations ranged from 0.165 to 0.306 g/cc. Apparent shear rates ranged from 1 to 10⁵ sec^?1. Five different solvents were employed. All of the flow curves can be reduced to a single master curve with the same shape exhibited by monodisperse polystyrenes and the Graessley theory. The shift factor for the shear rate axis, τ₀, approximately parallels the Rouse relaxation time, τ_R, but shows a residual concentration and solvent dependence not predicted by the Rouse form. For different solvents at the same concentration, better solvents show a minimum relative zero shear viscosity, η₀/η_s, and a maximum ratio τ_R/τ₀. It is concluded that all solvent effects are not adequately incorporated into the zero shear viscosity for the purposes of constructing master plots; however, the shape of the master plot is not affected by the solvent or the polymer block structure.     

The role of user requirements in data repository design

International Journal on Software Tools for Technology Transfer - Requirements engineering plays a crucial role in the development process of an information system as it aims at providing a...     

Overview of R&D at TLK for process and analytical issues on tritium management in breeder blankets of ITER and DEMO

Safe, reliable, and efficient tritium management in the breeder blanket will have to face unprecedented technological challenges. Beside the efficiency for tritium recovery from the breeder blanket (Tritium Extraction (TES) and Coolant Purification Systems (CPS)), the accuracy for tritium tracking between the inner and the outer fuel cycle must also be demonstrated. This paper focuses on the recent R&D carried out at the Tritium Laboratory Karlsruhe to tackle these issues. For ITER, the recently consolidated TES and CPS designs comprise adsorption columns and getter beds operated in semi-continuous mode. Different approaches for the tritium accountancy stage (TAS) have been evaluated. Balancing static (batch-wise gas collection at the TBM outlets and the tritium plant) or dynamic (in/on-line) approaches with respect to the expected analytical performances and integration issues, the first conceptual design of the TAS for EU TBMs is presented. For DEMO, the overall strategy for tritium recovery and tracking has been revisited. The necessity for on-line real-time tritium accountancy and improved process efficiency suggest the use of continuous processes such as permeator and catalytic membrane reactor. The main benefits combining the PERMCAT process with advanced membranes is discussed with respect to process improvements and facilitated accountancy using spectroscopic methods.     

Zur Prüfung und Bewertung der Umweltverträglichkeit von Holzschutzmitteln

Wood preservation can be made more environmentally compatible (1) by confining the use of wood preservative chemicals to the necessary minimum, and (2) by the use of effective and at the same time environmentally compatible wood preservatives. The aims and main points of testing and evaluating the environmental compatibility of wood preservatives are described. Crucial in this concern is the emission rate of the active ingredients of the wood preservatives (which leave the impregnated wood by leaching or evaporation), and this rate should be as low as possible for reasons of both long-term efficacy and low environmental load. The main pathways of possible environmental input of the active ingredients are leaching and evaporation during storage, transport and use of the impregnated wood and the input of their components or decomposition products during waste management. Looking at the leaching of non-fixing, not yet fixed as well as fixed wood preservative salts and organic active substances some problems arising in the practice of wood preservation and in the evaluation of the environmental compatibility of wood preservatives are dealt with and possible solutions are demonstrated.     

Energy expenditure of a noncontact boxing training session compared with submaximal treadmill running

The aim of this study was to determine the energy expenditure of a 1-h noncontact boxing training session and to compare these results with the energy expenditure of a more conventional recreational activity such as running. Eight healthy males, accustomed to noncontact boxing training, were recruited for the study. Subjects underwent three tests: (i) a boxing training session in the laboratory during which energy expenditure was measured continuously using indirect calorimetry (BOXL), (ii) a boxing training session in a boxing studio during which heart rate was measured continuously (BOXS), and (iii) an incremental running test on the treadmill during which energy expenditure was measured continuously. The energy expenditure during 60 min of BOXL ranged between 2519 and 3079 kJ (2821 +/- 190 kJ). Seven of the 8 subjects had higher heart rates during BOXL compared with those during BOXS, suggesting that the subjects exercised at a slightly higher intensity during BOXL, possibly because of the "one on one" supervision. A typical boxing training session lasting 60 min causes a person to expend 2821 +/- 190 kJ x h(-1), the same amount of energy as someone running about 9 km in 60 min on the treadmill.     

Spiral Tunneling Cracks Induced by Environmental Stress Cracking in LaRC™-TPI Adhesives

Some currently-available formulations of LaRC?-TPI, a thermoplastic polyimide originally developed at NASA-Langley, were found to be highly susceptible to environmental stress cracking when exposed to solvents such as acetone, toluene, diglyme and methyl ethyl ketone. The combination of stress and solvent led to rapid cracking in films and adhesive layers of this material system. Residual cool-down stresses induced when the LaRC-TPI is used as an adhesive or coating led, in the presence of a solvent, to dense “mud crack” patterns which relieve a portion of the stored energy. Because these through-the-thickness cracks are not able to relieve the stored energy in the vicinity of the adherends, additional fractures in the form of curious spiral tunnel cracks initiated and grew inward within each adhesive fragment. Micrographs of the spiral fractures are given, along with a qualitative explanation for the failure process as observed in adhesives and coatings.