Rapsölbasische Druckübertragungsmedien – Aufgaben,Anforderungen, Stand der Technik

Rapeseed Oil in Hydraulic Systems – Tasks, Requirements and Stand of the Art Rapeseed oil based hydraulic fluids have a lower level of ecotoxidity in comparison to the conventional petroleum-based lubricants and can be considered environmentally acceptable. Amongst the ecological point of view the acceptance of these fluids depends on several other aspects like economics and technology. In response to the growing interest in environmentally acceptable lubricants a hydraulic oil development program was initiated. Lubricant performance data, including laboratory evaluation and test experience, for a vegetable-based hydraulic fluid will be presented, identifying performance strengths and weaknesses.     

Zur Problematik des Blondierens menschlicher Haare

Problems Concerning Bleaching of Human Hair The bleaching of human hair using alkaline hydrogen peroxide involves a chemical change of the coloring pigments eumelanin and pheomelanin – the bleaching proper – as well as a chemical effect on the keratinous material – i. e. hair damage. The oxidation by alkaline hydrogen peroxide may proceed by different mechanisms and via different intermediates. It is discussed whether the reactions leading to bleaching or hair damage, respectively, show preferences for particular mechanisms of hydrogen peroxide decomposition.     

Influence of reading level difficulty on the disfluencies of normal children

This study assessed the effect of increasing the difficulty of reading material on the frequency and type of disfluency in the oral reading of normally fluent elementary school children. Eighty children participated in the study. Ten boys and 10 girls each, from Grades 3, 4, 5, and 6, read five 200-word passages, corresponding to one grade below their school placement, the grade of their school placement, and one, two, and three grades above their school placement. Results indicated a significant increase in total moments of disfluency and four specific types of disfluency as the difficulty of reading material increased. The data revealed a tendency for "stuttering" disfluencies to increase more in frequency than "normal" nonfluencies. Results are discussed with respect to theoretical and experimental implications.     

Schutz der Haare vor Witterungseinflüssen durch Vitamin E

The Protection of Hair against Weathering with Vitamin E The long-term damage to hair from weathering was simulated by irradiation with artificial sunlight. Irradiation causes bleaching of brown hair strands and affects the mechanical stability of the hair fibers. By prophylactic treatment with a hair rinse containing vitamin E, the light-induced damage to the keratin is markedly reduced. In contrast to this, a hair rinse without vitamin E does not provide any protection against light. The inhibitory effect of vitamin E on light-induced hair damage is discussed on the basis of its antioxidant effect.     

The SENTINEL project

Health-care expenditure on radiological equipment in Europe is a growing fraction of the gross domestic product for all member states. This increase in expenditure has been driven by technical developments in equipment design, matched by the introduction of novel clinical practices, examinations and procedures. The radiation protection implications of these developments have to be assessed. The SENTINEL co-ordination action covered radiation protection, safety and related issues that arise from these technical and clinical developments. SENTINEL covered 90% of patient examinations in European Radiology, 60% of the collective dose from medical sources and approximately 50% of the collective dose to European citizens from man-made sources. The SENTINEL co-ordination actions 'main' objective was to address the safety and efficacy issues which are common to all digital diagnostic imaging systems, including nuclear medicine. High-dose procedures and sensitive groups (such as children) were covered by the project. Specifically, the co-ordination action aimed: (1) to establish both physical and clinical image quality criteria and link the two, (2) to undertake a series of dosimetry studies to establish the reference levels for new procedures and (3) to develop good practice guidelines for radiation protection in digital imaging and produce training material.     

Assessment of patient organ dose in CT virtual colonoscopy for bowel cancer screening

Justification and optimisation form the basic elements for the radiological protection of individuals for medical exposures. Justification includes the assessment of patient organ doses from which radiation risks are deduced. Medical radiation exposures are justified only in the case of a sufficient net benefit. For screening examinations, such as CT virtual colonoscopy, this implies that patient organ doses should be relatively low to minimise the radiation detriment. Image quality should be sufficient to maximise the potential diagnostic benefits. The Medical Exposures Directive places special attention on medical exposures as part of health screening programmes and examinations involving high individual doses to the patient, both of which apply to CT virtual colonoscopy. Technical factors were recorded for a series of patients having virtual colonoscopy on a CT scanner. In addition, the dose-length product was assessed. Patient organ doses were deduced using a CT dose calculation program. The typical effective dose was 7.5 mSv for male patients and 10.2 mSv for female patients. The effective dose is higher for female patients, as some gender-specific organs are irradiated during virtual colonoscopy. Each patient has two series of scans resulting in doses of 15 mSv for male patients and 20 mSv for female patients.     

Value of preoperative chest X-ray examinations in children

To assess the value of routine preoperative chest x-ray films in pediatric patients, a prospective study of 1,500 patients, ages newborn to 19 years, was undertaken. Of all the patients, 7.5% demonstrated at least one roentgenographic abnormality, with 4.7% of the patients demonstrating a totally unsuspected significant roentgenographic anomaly. In 3.8% of the patients, surgery was eihter postponed or cancelled or the anesthetic technique was altered as a result of the roentgenographic finding. It is believed that the routine preoperative chest film is justified if the film is evaluated before surgery and the results clinically followed up.     

Theoretische Untersuchung des Einschmelzverhaltens einer Einzelkugel

Erstellung eines mathematischen Modells zur Berechnung des Abschmelzverhaltens von Einzelkugeln. Dimensionslose Formulierung der Differentialgleichung und ihrer Randbedingungen. Herleitung analytischer Gleichungen für zwei Grenzfälle, zwischen denen das reale Abschmelzverhalten liegt. Numerische Lösung. Diskussion einer einfachen Näherungsgleichung.