Nonlinear Maxwell behavior of sodium silicate glass in the surroundings of glass transition temperature

Presented are results from uniaxial cylinder upsetting tests of sodium silicate glass at different constant deformation rates each combined with relaxation experiments in the temperature range 480 to 580°C. Due to the complete stress relaxation to final load zero (vanished carrying capacity) also below glass transition temperature Tg, it follows Maxwell behavior in principle. But the rheological analyses of loading and unloading experiments together show that only nonlinear Maxwell model approaches can adequately describe the deformation behavior of the glass in the surroundings of Tg

Mechanical properties of sheet glass at high pressure during indentation experiments

Viscous flow is responsible for permanent deformation of glasses above the transformation temperature (Tg). The results of macroscopic indentation experiments (maximum loading forces Fmax ≥ 2 N) with sharp indenters (Vickers or Berkovich pyramids) demonstrate this property by crack-free indents at T ≥ Tg. But it is also possible to make crack-free indents at room temperature (RT), well below Tg, if the load, the contact area and the deformation rate, respectively, are small enough, which is consistent with glass as a supercooled liquid but inconsistent with glass as a well-known ideally brittle material at RT The mechanisms of this permanent deformation of glasses by indentation near RT have not been understood completely up to now. For the analysis of the macroscopic indentation experiments with Vickers pyramids and spherical indenters, respectively, a viscoelastic deformation behaviour is assumed for the complete temperature range from RT to Tg. Therefore the rheological analysis of all experiments were performed with the help of a simple Maxwell model. The results of Vickers indentation experiments were compared with cylinder compression experiments and ball indentation experiments which were analysed by the same rheological principles

Viscosity of glass below the transformation temperature

Glass is an ideally brittle material at room temperature. The results of hardness indentation tests demonstrate this property by crack formation at the corners of the indent. But it is possible to avoid the crack formation if the load, the contact area and the deformation rate, respectively, are small enough. The mechanisms of this permanent deformation of brittle glasses by indentation close to room temperature have not been understood completely up to now. Viscous flow is responsible for permanent deformation of glasses above the transformation temperature (Tg). The same mechanism of deformation during indentation experiments is assumed in this work hypothetically, taking into account the very high stresses (GPa range) in the local volume around the indenter tip. This hypothesis of deformation at room temperature will be verified by independent experiments that work like viscometers in principle (e.g. cylinder compression experiments, ball indentation experiments). All experiments were analysed with the help of simple rheological models. Additionally some ball indents were analysed by topographical investigations to get first hints of viscoelastic deformation behaviour below Tg of glass

TG-FTIR measurement of CO2-H2O co-adsorption for CO2 air capture sorbent screening

Capturing atmospheric CO2 using solid sorbents is gaining interest. As ambient air normally contains much more (up to 100 times) water than CO2, a selective sorbent is desirable as co-adsorption will most likely occur. In this study, a convenient method based on an TG-FTIR analysis system is developed and used to characterize sorbents for their water and CO2 adsorption capacity when exposed to ambient air. The method allows to determine quantitatively the co-adsorbed amounts of CO2 and water from small sample sizes (10 mg range) and is expected to be a useful instrument in sorbent screening and evaluatio

Editorial: diet, inflammation and colorectal cancer

This Research Topic was designed to provide the reader with an overview of the impact of body weight and adiposity, as well as of specific food compounds on the inflammatory status in health and disease states, such as CRC. We collected original and review articles featuring the role of specific food compounds in the regulation of immune response and their potential therapeutic implications, the effect of polyunsaturated fatty acids (PUFA), oligosaccharides, polyphenols and body weight in the modulation of inflammation and long-term disease outcomes, highlighting the link between diet, inflammation, and CRC

High-throughput Soxhlet extraction method applied for analysis of leaf lignocellulose and non-structural substances

The traditional Soxhlet extraction method is commonly employed to extract soluble components from non-soluble components in a solid matrix, for example, non-structural substances in biomass samples that can be separated from structural lignocellulosic compounds in biomass samples. Conventional laboratory procedures for such extractions typically involve a low sample throughput, with each run being performed individually, resulting in time-consuming and labour-intensive processes, making them impractical for analysing large sample sets. In research fields such as Earth Observation in Forest Ecosystems, extensive fieldwork sampling is required across large study areas, resulting in a substantial number of leaf samples, each with limited mass. In this study, an innovative adaptation of the conventional National Renewable Energy Laboratory (NREL) Soxhlet method is developed to create a high-throughput mini-Soxhlet apparatus that enables the simultaneous extraction of up to nineteen samples, each with a mass of 0.3 g per sample. With this adaptation, we measured the lignocellulose and extractive in 343 leaf samples collected from four temperate forest tree species. This modified approach enhances versatility and can be applied to all solid-liquid extractions and various types of vegetation tissues, such as tree leaves, shrubs, crops, feedstock, and other non-woody samples.• The solid-liquid extraction method has been implemented in a heating block facilitating 19 small flasks to measure multiple samples simultaneously while requiring only a small sample mass.• The apparatus set-up was constructed using an alumina heating block mounted on a standard laboratory heating plate. Boiling flask tubes were placed in the heating block and equipped with condenser caps and filters on glass rods on which the solid samples were placed.• The adjustments made the method suitable for application to diverse vegetation tissues and non-woody sample types. It holds particular appeal for research areas that necessitate a high sample number

Range estimation system for powered wheelchairs

In this paper, we present a method to estimate a wheelchair’s power consumption and therefore its battery autonomy. The wheelchair powertrain is modeled to enable a virtual driving simulation. The use of a white box model enables an adaption to other systems and configurations. This model outputs the actual battery and motor currents within a simulation for a given route and speed profile. These currents affect the battery’s SoC, whose total charge depends on its temperature. To account changes of the available charge, a simplistic model of the battery’s temperature dependence is introduced, that has been acquired via discharge cycles within a climate chamber. Furthermore, an a priori simulation uses the model to estimate the SoC after the virtual completion of a route with a corresponding height and velocity profile. Finally, the paper compares the results of the simulation with real measurements using the recorded tracks and the generated virtual routes. Since the input for the a priori estimation relies on virtual routes, their quality is assessed as well

Disruption of the murine major vault protein (MVP/LRP) gene does not induce hypersensitivity to cytostatics

Vaults are ribonucleoprotein particles with a distinct structure and a high degree of conservation between species. Although no function has been assigned to the complex yet, there is some evidence for a role of vaults in multidrug resistance. To confirm a direct relation between vaults and multidrug resistance, and to investigate other possible functions of vaults, we have generated a major vault protein (MVP/lung resistance-related protein) knockout mouse model. The MVP(-/-) mice are viable, healthy, and show no obvious abnormalities. We investigated the sensitivity of MVP(-/-) embryonic stem cells and bone marrow cells derived from the MVP-deficient mice to various cytostatic agents with different mechanisms of action. Neither the MVP(-/-) embryonic stem cells nor the MVP(-/-) bone marrow cells showed an increased sensitivity to any of the drugs examined, as compared with wild-type cells. Furthermore, the activities of the ABC-transporters P-glycoprotein, multidrug resistance-associated protein and breast cancer resistance protein were unaltered on MVP deletion in these cells. In addition, MVP wild-type and deficient mice were treated with the anthracycline doxorubicin. Both groups of mice responded similarly to the doxorubicin treatment. Our results suggest that MVP/vaults are not directly involved in the resistance to cytostatic agents

Silver-Mobility - near field mobility concepts for the age group 50+

The research group “Silver-Mobility - near-field mobility concepts for the age group 50plus” develops concepts to support elder people with beginning or advanced loss of their personal key mobility. Also the improvements of existing systems to substitute loosen abilities like wheel-chairs are in focus of the research group. The paper gives an overview about the approaches and some resulting concepts, mainly for overcoming of obstacles with wheel-based mobility aids, for energy storing solutions and for different assistance systems for mobility aids. The main principle for all these concepts was to get know and analyze the future users, their requirements and needs and then derive solutions from these analyses. The results show the necessity to develop adaptable, individualisable and re-configurable systems