Search

This study reports a wet spinning method to spin composite micro-fibres of 2D liquid crystalline graphene oxide (GO) and exfoliated MoS2 nanosheets with very high MoS2 loading. The MoS2 dispersion was found to be isotropic irrespective of solvent type or solute concentration in the dispersion and thus found to be non-spinnable via wet spinning process. The liquid crystallinity of GO induces birefringence in the composite dispersion and enables the spinning of the composite dispersion containing high loading of MoS2 with great flexibility. We were able to spin composite microfibers with 69 wt% MoS2 loading for the first time. The resulting fibres were annealed at high temperature to produce flexible conductive rGO#MoS2 fibres. Scanning electron microscopy (SEM) and Raman analysis strongly suggest homogeneous distribution of MoS2 throughout the fibres. Mechanical properties of the fibres were studied and maximum tensile strength (76.5 MPa) and Young's modulus (13.3 GPa) obtained with 10 wt% MoS2 loading. All solid-state flexible symmetric supercapacitor from these composite fibres was fabricated and the electrochemical performance was studied. The electrochemical study shows high areal capacitance of the produced composite fibres (as high as 282.6 mF cm−2) with good cycling stability (82.5% capacitance retention after 5000 cycles) that indicates high potential of these composite fibres as energy storage system for smart textile of the future.

International audience

Due to this high number of produced units and the very thin sheet metals used for beverage cans, precise production processes with high production volumes are necessary. To save expenses, while optimising these processes, numerical simulation methods are exploited. Considering this, it is indispensable to identify the material behaviour as exactly as possible. In practise, often results of quasi static tensile tests are used, although these are insufficient for the precise modelling of the material behaviour during can production, since strain rates of up to 10³ s-1 can occur, here. Therefore, quasi static and high speed tensile test have been done on specimens featuring the typical materials and thicknesses of semi-finished parts used for beverage can production. The results were compared with similar materials at higher sheet metal thicknesses and authenticated by numerical simulation. It was shown that there is an influence of the strain rate on the material behaviour and it is necessary to determine material characteristics at strain rates, which are close to the process speed. Furthermore, the results were classified in their signification for beverage can production and forming technologies in general.

Twenty-five scientists met at Aschauhof, Altenhof, Germany, to discuss various aspects of the complex network of modern health screening, focusing on current scientific topics including medical sciences, human biology, and mathematics; on problems in implementing these results at the practical level of physicians, nurses, technicians, and engineers; and the level of administrative and political decisions. Whereas major scientific advancements have been published in the understanding and the bio-statistical evaluation of anthropometric screening parameters such as serial measurements of height and weight for preventive medical check-ups, BMI screening and surveillance in schools, etc., the implementation of these advancements into current health screening concepts, strategies and decision-making is poor. Fear of discrimination, misperception of body image, behavioural responses and political concerns, meanwhile dominate and negatively interfere with the implementation of recent scientific results into public health screening concepts and practices.

The association between poverty, malnutrition, illness and poor socioeconomic conditions on the one side, and poor growth and short adult stature on the other side, is well recognized. Yet, the simple assumption by implication that poor growth and short stature result from poor living conditions, should be questioned. Recent evidence on the impact of the social network on adolescent growth and adult height further challenges the traditional concept of growth being a mirror of health. Twenty-nine scientists met at Glücksburg castle, Northern Germany, November 15th - 17th 2013, to discuss genetic, endocrine, mathematical and psychological aspects and related issues, of child and adolescent growth and final height.

Auxology has developed from mere describing child and adolescent growth into a vivid and interdisciplinary research area encompassing human biologists, physicians, social scientists, economists and biostatisticians. The meeting illustrated the diversity in auxology, with the various social, medical, biological and biostatistical aspects in studies on child growth and development.

Bei der Auslegung von Werkzeugmaschinen ist die statische und dynamische Steifigkeit ein entscheidendes Bewertungskriterium, welches schon während des Konstruktionsprozesses Berücksichtigung finden muss. Die dynamische Steifigkeit wird dabei wesentlich von der Regelung bestimmt, da sich der 'mechatronische Steifigkeitspfad' über die Messsysteme und Antriebe mit Regelung schließt. Die statische Genauigkeit einer Maschinenachse wird dagegen hauptsächlich von der Auflösung der Messsysteme und der mechanischen Steifigkeit beeinflusst. Im Beitrag wird gezeigt, wie FEM (Finite-Elemente-Methode)-Modelle für die Berechnung der statischen Steifigkeit geregelter Vorschubachsen genutzt werden können und wie mechatronische Modelle für die verbesserte Ermittlung der statischen und dynamischen Steifigkeit eingesetzt werden. Ziel ist es, aufzuzeigen, wie der Einsatz beider Varianten zur Ermittlung der statischen Steifigkeit an Werkzeugmaschinen unter Beachtung der speziellen Eigenschaften geregelter Vorschubachsen dienen kann. Dem Anwender soll bewusst werden, dass eine ausschließliche Untersuchung der Mechanik nicht ausreicht.

In the context of virtual development processes of mechatronic systems like machine tools, the preventive assessment of the effects of light-weight structural components on the characteristics of controlled feed systems and therefore on the power- and energy requirement of machine tools is of great importance. The modelling of the damping is often limited in practical computation of real machine tools, because they are mostly limited to proportional damping characteristics. Yet the presence of discrete dampers, as for instance, in damping units in guides, or known diverse material damping in construction (components made of glass- or carbon fibre reinforced plastic), demands that the possibility of observance of non-proportional damping, in regard to later model-updating, has to be given. The article demonstrates the theoretical state-space modelling of non-proportional damped mechanics using the example of a biaxial vertical lathe.