Office task effects on comfort and body dynamics in five dynamic office chairs

In the present study, we investigated the effect of office tasks on posture and movements in field settings, and the comfort rating for chair characteristics and correlation with type of task. The tasks studied were: computer work, telephoning, desk work and conversation. Postures, movements, chair part inclinations and comfort rating data were collected from 12 subjects. Computer work showed the lowest physical activity, together with upright trunk and head position and low backrest inclination. Conversation shows the highest activity of head legs and low back together with the highest cervical spine extension. In contrast, desk work provoked the most cervical spine flexion and showed the second lowest activity. The telephoning tasks showed medium activity and the highest kyphosis. Conversation showed the highest backrest inclination. Positive comfort relations were found for computer work and a "swing system" chair, for telephoning and an active longitudinal seat rotation, and for desk work and a chair with a three-dimensionally moveable seat.     

Geometric design of motions constrained by a contacting surface pair

We discuss the following problem which arises in robot motion planning, NC machining and computer animation: Given are a fixed surface Ψ and N positions Φ_i of a moving surface Φ such that the Φ_i are in point contact with Ψ. Compute a smooth and fair Euclidean gliding motion Φ(t) of the surface Φ on the surface Ψ which interpolates (or approximates) the given positions Φ_i at time instances t_i. First we generalize interpolatory variational subdivision algorithms for curves to curves on surfaces. Second we study an unconstraint motion design algorithm which we then extend to the main contribution of this paper, an algorithm for the design of a motion constraint by a contacting surface pair. Both motion design algorithms use a feature point representation of the moving surface, subdivision algorithms for curves, instantaneous kinematics, and ideas from line geometry. Geometric methods are used for the numerical solution of the arising optimization problems.     

Catalytic performance of methacrylate‐based poly‐4‐(dialkylamino)‐pyridines: activity prediction via NMR shifts

The synthesis of the 4‐(dialkylamino)pyridine derivative 3‐(4‐(pyridin‐4‐yl)piperazin‐1‐yl)propyl methacrylate and its copolymerization with n‐butyl methacrylate are presented. The catalytic activity was evaluated in the acylation of tert‐butanol with acetic anhydride yielding tert‐butyl acetate. It is observed that the activity of polymer‐attached 4‐(dimethylamino)pyridine analogues correlates remarkably well with the chemical shift of the β‐pyridyl protons. Differences in catalytic efficiency result from distinct electronic densities of the pyridine ring, while embedding the catalytically active moiety into a polymeric structure has nearly no deleterious effect on the performance. © 2015 Society of Chemical Industry     

Oxidation resistant ceramic foam from a silicone preceramic polymer/polyurethane blend

Silicon oxycarbide (SiOC) ceramic foams, produced by the pyrolysis of a foamed blend of a methylsilicone preceramic polymer and polyurethane (PU) in a 1/1 wt.% ratio, exhibit excellent physical and mechanical properties. The proposed process allows to easily modify the density and morphology of the foams, making them suitable for several engineering applications. However, it has been shown that, due to residual carbon present in the oxycarbide phase after pyrolysis, the foams are subjected to an oxidation process that reduces their strength after high temperature exposure to air (12 h 1200°C). A modified process, employing the same silicone resin preceramic polymer but a much lower PU content (silicone resin/PU=5.25/1 wt.% ratio), has been developed and is reported in this paper. Microstructural investigations showed that carbon rich regions deriving from the decomposition of the polyurethane template are still present in the SiOC foam, but have a much smaller dimension than those found in foams with a higher PU content. Thermal gravimetric studies performed in air or oxygen showed that the low-PU containing ceramic foams display an excellent oxidation resistance, because the carbon-rich areas are embedded inside the struts or cell walls and are thus protected by the dense silicon oxycarbide matrix surrounding them. SiOC foams obtained with the novel process are capable to maintain their mechanical strength after oxidation treatments at 800 and 1200°C (12 h), while SiOC foams obtained with a higher amount of PU show about a 30% strength decrease after oxidation at 1200°C (12 h).     

Newly Isolated Animal Pathogen Corynebacterium silvaticum Is Cytotoxic to Human Epithelial Cells

Corynebacterium silvaticum is a newly identified animal pathogen of forest animals such as roe deer and wild boars. The species is closely related to the emerging human pathogen Corynebacterium ulcerans and the widely distributed animal pathogen Corynebacterium pseudotuberculosis. In this study, Corynebacterium silvaticum strain W25 was characterized with respect to its interaction with human cell lines. Microscopy, measurement of transepithelial electric resistance and cytotoxicity assays revealed detrimental effects of C. silvaticum to different human epithelial cell lines and to an invertebrate animal model, Galleria mellonella larvae, comparable to diphtheria toxin-secreting C. ulcerans. Furthermore, the results obtained may indicate a considerable zoonotic potential of this newly identified species.     

Sechster Nationaler IT-Gipfel 2011 in München

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