Eighty years of macromolecular science: from birth to nano-, bio- and self-assembling polymers—with slight emphasis on European contributions

A definition of macromolecular science (as opposed to polymer science and engineering) is given, from which the year 1930 is derived as the year of its birth. The scope of treatment of this paper will be limited to solid technical polymers. Some important discoveries of polymer technology in the nineteenth century are reviewed together with the reason why the concept of macromolecules and the theory of rubber elasticity did not emerge earlier. The role of chain backbones in structure formation and mechanical loading of technical polymers has been heavily discussed ever since and has attracted this author for most of his scientific work. He offers a personal perspective of the most important achievements in three domains of macromolecular science: the synthesis of well-designed chain molecules, structural characterization and the understanding of the micro-mechanics of (nano-structured) polymer materials. Progress is generally documented by citing individual references from the discussed periods—well knowing that the development of science is due to the contributions of many more people. In conclusion, a critical outlook will be attempted on future trends in the design and application of well-adapted—and frequently complex—polymer systems towards growing human need

Theoretical Consideration of the Influence of Reforming Processes on the Fracture Strength of Solids Technical Report No. 105

Reformation processes effect on stress time-to- fracture behavior of solid

Kinetic considerations of the strength of oriented solids

Kinetics of mechanical strength of oriented and stressed solids based on statistical absolute reaction rate theor

Eighty years of macromolecular science: from birth to nano-, bio- and self-assembling polymers-with slight emphasis on European contributions

A definition of macromolecular science (as opposed to polymer science and engineering) is given, from which the year 1930 is derived as the year of its birth. The scope of treatment of this paper will be limited to solid technical polymers. Some important discoveries of polymer technology in the nineteenth century are reviewed together with the reason why the concept of macromolecules and the theory of rubber elasticity did not emerge earlier. The role of chain backbones in structure formation and mechanical loading of technical polymers has been heavily discussed ever since and has attracted this author for most of his scientific work. He offers a personal perspective of the most important achievements in three domains of macromolecular science: the synthesis of well-designed chain molecules, structural characterization and the understanding of the micro-mechanics of (nano-structured) polymer materials. Progress is generally documented by citing individual references from the discussed periods-well knowing that the development of science is due to the contributions of many more people. In conclusion, a critical outlook will be attempted on future trends in the design and application of well-adapted-and frequently complex-polymer systems towards growing human needs

GESTIÓN DE INTERNACIONALIZACIÓN EN UNIVERSIDADES PRIVADAS DE ASUNCIÓN Y DEPARTAMENTO CENTRAL ENTRE LOS AÑOS 2017 – 2020

A internacionalização do ensino superior ganhou impulso nas últimas décadas, dado o papel preponderante que as universidades desempenham numa sociedade onde o conhecimento se tornou global. O objetivo do estudo foi descrever os esforços de internacionalização em universidades privadas de Assunção e Central, executados entre os anos de 2017 - 2020. Foi de design não experimental, abordagem mista e paradigma interpretativo usando a pesquisa e análise de conteúdo, por meio do questionário e matriz de conteúdo. A amostragem foi não probabilística de especialistas, por conveniência e voluntários; A amostra foi composta por 10 gestores com ligação às relações internacionais. Foram escolhidos documentos gerados pelas universidades encontrados em páginas da web. Os resultados revelaram que nenhuma das instituições possuía um modelo específico de internacionalização, suas ações eram baseadas em um modelo educacional próprio referente à missão e visão; Declararam ter alcançado maior visibilidade e prestígio internacional em relação a outras instituições, embora a maioria tenha considerado a demanda de tempo envolvida na gestão da internacionalização como um ponto fraco. A mobilidade acadêmica foi a escolha majoritária como ação que durante a pandemia de Covid-19 foi representada pela participação em congressos, seminários ou workshops com projetos de pesquisa conjuntos. Os esforços de internacionalização eram incipientes, pois não havia um marco regulatório específico que o contemplasse. Sugere-se assumir a internacionalização como um compromisso inerente à gestão institucional, desenvolvendo estratégias inovadoras que potencializem as funções substantivas do ensino superior

Planning, Optimisation and Evaluation of Small Power-to-Gas-to-Power Systems: Case Study of a German Dairy

In the course of the energy transition, distributed, hybrid energy systems, such as the combination of photovoltaic (PV) and battery storages, is increasingly being used for economic and ecological reasons. However, renewable electricity generation is highly volatile, and storage capacity is usually limited. Nowadays, a new storage component is emerging: the power-to-gas-to-power (PtGtP) technology, which is able to store electricity in the form of hydrogen even over longer periods of time. Although this technology is technically well understood and developed, there are hardly any evaluations and feasibility studies of its widespread integration into current distributed energy systems under realistic legal and economic market conditions. In order to be able to give such an assessment, we develop a methodology and model that optimises the sizing and operation of a PtGtP system as part of a hybrid energy system under current German market conditions. The evaluation is based on a multi-criteria approach optimising for both costs and CO2 emissions. For this purpose, a brute-force-based optimal design approach is used to determine optimal system sizes, combined with the energy system simulation tool oemof.solph. In order to gain further insights into this technology and its future prospects, a sensitivity analysis is carried out. The methodology is used to examine the case study of a German dairy and shows that PtGtP is not yet profitable but promising. View Full-Tex

A Multiscale Model of Partial Melts 2: Numerical Results

In a companion paper, equations for partially molten media were derived using two-scale homogenization theory. One advantage of homogenization is that material properties, such as permeability and viscosity, readily emerge. A caveat is that the dependence of these parameters upon the microstructure is not self-evident. In particular, one seeks to relate them to the porosity. In this paper, we numerically solve ensembles of the cell problems from which these quantities emerge. Using this data, we estimate relationships between the parameters and the porosity. In particular, the bulk viscosity appears to be inversely proportional to the porosity. Finally, we synthesize these numerical estimates with the models. Our hybrid numerical--analytical model predicts that the compaction length vanishes with porosity.Comment: 50 pages, submitted to JGR Solid Eart

Back-arc strain in subduction zones: Statistical observations versus numerical modeling

International audience1] Recent statistical analysis by Lallemand et al. (2008) of subduction zone parameters revealed that the back-arc deformation mode depends on the combination between the subducting (nu(sub)) and upper (nu(up)) plate velocities. No significant strain is recorded in the arc area if plate kinematics verifies nu(up) = 0.5 vsub - 2.3 (cm/a) in the HS3 reference frame. Arc spreading ( shortening) occurs if nu(up) is greater ( lower) than the preceding relationship. We test this statistical law with numerical models of subduction, by applying constant plate velocities far away from the subduction zone. The subducting lithosphere is free to deform at all depths. We quantify the force applied on the two converging plates to sustain constant surface velocities. The simulated rheology combined viscous (non-Newtonian) and brittle behaviors, and depends on water content. The influence of subduction rate vs is first studied for a fixed upper plate. After 950 km of convergence ( steady state slab pull), the transition from extensional to compressive stresses in the upper plate occurs for vs similar to 1.4 cm/a. The effect of upper plate velocity is then tested at constant subduction rate. Upper plate retreat ( advance) with respect to the trench increases extension ( compression) in the arc lithosphere and increases ( decreases) the subducting plate dip. Our modeling confirms the statistical kinematic relationship between vsub and nu(up) that describes the transition from extensional to compressive stresses in the arc lithosphere, even if the modeled law is shifted toward higher rates of upper plate retreat, using our set of physical parameters ( e. g., 100 km thick subducting oceanic plate) and short- term simulations. Our results make valid the choice of the HS3 reference frame for assessing plate velocity influence on arc tectonic regime. The subduction model suggests that friction along the interplate contact and the mantle Stokes reaction could be the two main forces competing against slab pull for upper mantle subductions. Besides, our simulations show that the arc deformation mode is strongly time dependent

Deep crustal earthquakes in North Tanzania, East Africa: Interplay between tectonic and magmatic processes in an incipient rift

International audienceIn this study, we explore the origin of lower crustal seismicity and the factors controlling rift propagation using seismological data recorded within the youngest part of the East African Rift System, the North Tanzanian Divergence (NTD). Most earthquakes below Lake Manyara occur at depth ranging between 20 and 40 km and have a swarm-like distribution. Focal mechanisms of 26 events indicate a combination of strike-slip and normal faulting involving Archaean basement structures and forming a relay zone. The derived local stress regime is transtensive and the minimum principal stress is oriented N110°E. Crustal seismic tomography reveals low-velocity anomalies below the rifted basins in the NTD, interpreted as localized thermomechanical perturbations promoting fluid release and subsequent seismicity in the lower crust. SKS splitting analysis in the NTD indicates seismic anisotropy beneath 17 stations most likely due to aligned magma lenses and/or dikes beneath the rift and to the lithospheric fabrics. Our results favor a strain pattern intermediate between purely mechanical and purely magmatic. We suggest that melt products arising from a large asthenospheric thermal anomaly enhance lithospheric weakening and facilitate faulting and creeping on critically oriented inherited structures of the Precambrian lower crust. Although the crust is unlikely weakened at a point comparable to other parts of the East African Rift System, this deep-seated thermomechanical process is efficient enough to allow slow rift propagation within the eastern Tanzanian cratonic edge