Photo-vulcanization using thiol-ene chemistry: Film formation,morphology and network characteristics of UV crosslinked rubber latices

The photo-vulcanization with versatile thiol-ene chemistry represents an innovative approach to crosslink diene-rubber materials both in latex and in solid film state. In this work, the structure of elastomer-based thiol-ene networks and the morphology after film formation are studied in detail using electron microscopic techniques, atomic force microscopy and multiple-quantum solid-state NMR spectroscopy. Additionally, film formation properties and corresponding macroscopic properties of photo-vulcanized natural rubber (NR) latex and its synthetic counterpart, isoprene rubber (IR) latex, are determined in dependence on the curing procedure (pre- and post-vulcanization). The results reveal that thiol-ene cured elastomers comprise homogenously distributed crosslinks with a low amount of short chain defects. Whilst photochemically pre-cured NR latex particles provide coherent films, the film formation and mechanical properties of IR are strongly governed by the crosslink density of the latex particles. In film state, photo-vulcanization promotes narrow crosslink distributions and excellent tensile properties of both NR and IR.     

Care of stroke patients by relatives--social support and coping strategies

OBJECTIVE: To assess the coping ability and the social support of relatives looking after patients who have had a stroke. Of special interest was to ascertain how coping behaviour and social support differed between short-term (caring period of 3-6 months) and long-term (caring period longer than 2 years) carers. Differences in social networking between relatives and a control group (no caring tasks) were also assessed. SUBJECTS AND METHODS: A questionnaire based on the well-established "Berne coping forms" and another on social support were filled in by 20 relatives (18 women, two men; mean age 50.6 years) after a short-term caring period of up to 6 months and 20 relatives after a caring period longer than 2 years (14 women, six men; mean age 64.9 years) and a control group (27 women, 10 men; mean age 57.8 years). RESULTS: Among the total group of relatives the coping strategies (listed by order of importance) were: "passive cooperation", "acceptance", and "lending a hand". The short- and long-term carers showed no significant differences in these strategies. However, there were significant deficits in social support between the relatives and the controls as to practical support (P < 0.05), social integration (P < 0.01), social support received (P < 0.01), social burden (P < 0.01) and the caring persons (P < 0.05). There was no difference regarding social support between the short- and long-term carers. CONCLUSIONS: The results confirm the importance of social support for relatives who look after stroke patients. Every form of psychosocial help should be given at the time the patient is discharged to home care. This would require day clinics and short-term places in nursing homes.     

Field stitching in thermal probe lithography by means of surface roughness correlation

A novel stitching method is presented which does not require special purpose alignment markers and which is particularly adapted to probe lithographic methods, enabling the writing of large patterns exceeding the size limitations imposed by high precision scan stages. The technique exploits the natural roughness of polymeric resist surfaces as a fingerprint marker for the sample position. Theoretical and experimental evidence is provided that sub-nanometer metrological accuracy can be achieved by inspecting the surface roughness in areas with 1?μm linear dimensions. The method has been put to the test in a thermal probe lithography experiment by writing a composite pattern consisting of five 10?μm ×?10?μm fields which are seamlessly joined together. The observed stitching error of 10?nm between fields is dominated by inaccuracies of the scanning hardware used in the experiment and is not fundamentally limited by the method per?se.     

Health surveillance using an occupational medical database

This pilot study sought associations between liver function tests (LFTs) and membership in homogeneous exposure groups (HEGs) at a target plant as pre-clinical indications of possible future occupational health problems. A large company database yielded linear models for each of six LFTs (total bilirubin, alkaline phosphatase, gammaglutamyl transferase, lactate dehydrogenase, aspartate transaminase, and alanine transaminase) in terms of sex, body mass index, age, race (white/non-white), alcohol and cigarette consumption, and production/non-production (P/NP) job, permitting control for these in analyses of LFTs vs HEGs at the plant. These analyses, with HEG substituted for P/NP in the large group model, resulted in loosely "suspect" associations significant at P < 0.10. Collapsed HEG variable (containing "suspects" separately and all other non-significant HEG levels pooled) yielded "confirmed suspects" at P < 0.05 in the analysis of an independent LFT set taken at the plant approximately one year later.     

A method for phase reconstruction from measurements obtained using a configured detector with a scanning transmission X-ray microscope

We developed a technique for performing quantitative phase reconstructions from differential phase contrast images obtained using a configured detector in a scanning transmission X-ray microscope geometry. The technique uses geometric optics to describe the interaction of the X-ray beam with the specimen, which allows interpretation of the measured intensities in terms of the derivative of the phase thickness. Integration of the resulting directional derivatives is performed using a Fourier integration technique. We demonstrate the approach by reconstructing simulated measurements of a 0.5-μm-diameter gold sphere at 7-keV photon energy.     

Thanatophoric dwarfism. Pathogenesis of the respiratory insufficiency in this abnormality

Report on a thanatophoric dwarfism, which is a variety of achondroplasia. New born children with this failure are not able to survive the first few days after birth. This early death is due to a cardiorespiratory deficiency as a consequence of the extremely short ribs but also of the abnormal cartilaginous growth in the wall of bronchi and bronchioles. In this present case of the thanatophoric dwarfism the question is discussed in how far the disorder of the bronchial cartilage is the basis of the respiratory distress.     

Turbulence triggers vigorous swimming but hinders motion strategy in planktonic copepods

Calanoid copepods represent a major component of the plankton community. These small animals reside in constantly flowing environments. Given the fundamental role of behaviour in their ecology, it is especially relevant to know how copepods perform in turbulent flows. By means of three-dimensional particle tracking velocimetry, we reconstructed the trajectories of hundreds of adult Eurytemora affinis swimming freely under realistic intensities of homogeneous turbulence. We demonstrate that swimming contributes substantially to the dynamics of copepods even when turbulence is significant. We show that the contribution of behaviour to the overall dynamics gradually reduces with turbulence intensity but regains significance at moderate intensity, allowing copepods to maintain a certain velocity relative to the flow. These results suggest that E. affinis has evolved an adaptive behavioural mechanism to retain swimming efficiency in turbulent flows. They suggest the ability of some copepods to respond to the hydrodynamic features of the surrounding flow. Such ability may improve survival and mating performance in complex and dynamic environments. However, moderate levels of turbulence cancelled gender-specific differences in the degree of space occupation and innate movement strategies. Our results suggest that the broadly accepted mate-searching strategies based on trajectory complexity and movement patterns are inefficient in energetic environments.     

Effect of Air Flow and Acceleration on Particle Size of Dry Powder Aerosols determined by Time-of-Flight Aerosol Beam Spectrometry

The effect of air flow and acceleration on the particle size distributions of two Turbuhalers containing drug loads of 0.5 and 1.3 mg per dose was determined with a time-of-flight aerosol beam spectrometer (Aerosizer®). While the particle size of both inhalers decreased with increasing flow and acceleration, the distributions became narrower and variability was reduced. Simultaneously, a decrease in the number and mass of particles measured was observed which was more pronounced for the 1.3 mg dose. Additionally the count rate for the 1.3 mg dose was lower than for 0.5 mg. These observations were accompanied by a remarkably fine particle size distribution for the high dose Turbuhaler®. It was concluded that the quantity of particles in the DPI aerosols exceeded the resolution of the Aerosizer, erroneously shifting the size distributions towards smaller diameters.

In addition, the DPI aerosols were analyzed with a Four Stage Impinger to evaluate the results. The particle size estimates obtained using the impinger were in the same range as those obtained at an acceleration of 5 L/s2 using the Aerosizer to study the 0.5 mg Turbuhaler. The Aerosizer produced significantly smaller particle sizes than the impinger in all cases evaluating the 1.3 mg Turbuhaler, supporting the theory of distorted particle size distributions due to particle overload.