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.     

Results of irradiation treatment in patients with non-resectable oesophageal cancer

Forty-eight patients with non-resectable cancer of the oesophagus and oesophagogastric junction (Group A: Stage I/II, 32; Group B: Stage III/IV, 16) underwent intraluminal Iridium-192 high dose-rate afterloading therapy (5-7 Gy/session, total dose: 5-21 Gy, mean: 12.4 Gy) and external beam irradiation (Karnofsky > or = 80% 50-60 Gy/2 Gy per day; Karnofsky 60-79%: 30 Gy/3 Gy per day). Durable satisfactory palliation (intake of at least semi-solid food) was demonstrated in 96% of patients. The mean survival for group A was 19.1 months and that for group B, 6.9 months, with a 12-month survival rate of 66% (group A) and 0% (group B) (P < 0.001). Local tumour response and complication rate were significantly dose-related with a predicted response rate of 70.5%, and a complication rate of 50% at ERD 129.3 Gy.     

Surfactant nebulization versus instillation during high frequency ventilation in surfactant-deficient rabbits

Glutamate-mediated excitotoxicity plays an important role in the degeneration of nigrostriatal dopamine (DA) neurons induced by 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP), although the role of the N-methyl D-aspartate (NMDA) receptor subtype in this process is still uncertain. We studied glutamate receptor subtype agonist-induced ionic currents in acutely dissociated DAergic neurons from the rat substantia nigra zona compacta (SNc) using the nystatin-perforated patch-clamp whole-cell recording technique. The results fall into four main categories. First, single neurons, freshly isolated from SNc, exhibited a large soma and multipolar morphology, responded to DA, and stained positively for tyrosine hydroxylase (TH). Second, rapid application of L-glutamate (> 10(-5) M) induced an inward current with minimal desensitization at a clamp voltage of -60 mV. Third, kainic acid (KA) or alpha-amino-3-hydroxy-5-methyl-isoxazole (AMPA) induced an inward current that was similar to the glutamate-induced current while, in the same neuron, NMDA (10(-4) M) failed to induce any current response in Mg2+-free solution that contained 10(-5) M glycine at a clamp voltage of -60 mV. Under the same experimental conditions, NMDA induced a clear current response in isolated substantia nigra reticulata (SNr) neurons. Fourth, the specific NMDA receptor antagonist DL-2-amino-5-phosphonovaleric acid (APV, 10(-4) M) failed to block 10(-4) M glutamate-induced inward current, while the specific KA/AMPA receptor antagonist 6-cyano-7-nitroguinoxaline-2, 3-dione (CNQX, 10(-5) M) completely blocked the glutamate-induced current. These results indicate that in single SNc DAergic neurons of 2-week-old rats, L-glutamate-induced inward current is mediated by non-NMDA receptors rather than by NMDA receptors.