Stress-strain behavior and geometrical properties of packings of elongated particles

We present a numerical analysis of the effect of particle elongation on the quasistatic behavior of sheared granular media by means of the Contact Dynamics method. The particle shapes are rounded-cap rectangles characterized by their elongation. The macroscopic and microstructural properties of several packings subjected to biaxial compression are analyzed as a function of particle elongation. We find that the shear strength is an increasing linear function of elongation. Performing an additive decomposition of the stress tensor based on a harmonic approximation of the angular dependence of branch vectors, contact normals and forces, we show that the increasing mobilization of friction force and the associated anisotropy are key effects of particle elongation. These effects are correlated with partial nematic ordering of the particles which tend to be oriented perpendicular to the major principal stress direction and form side-to-side contacts. However, the force transmission is found to be mainly guided by cap-to-side contacts, which represent the largest fraction of contacts for the most elongated particles. Another interesting finding is that, in contrast to shear strength, the solid fraction first increases with particle elongation, but declines as the particles become more elongated. It is also remarkable that the coordination number does not follow this trend so that the packings of more elongated particles are looser but more strongly connected.Comment: Submited to Physical Review

The use of hydroxychloroquine as a systemic treatment in erosive lichen planus of the vulva and vagina

Erosive lichen planus affecting the vulva and vagina (ELPV) is a rare inflammatory skin disease, presenting with painful erosions and severe scarring.1 The disease course is persistent and often refractory to treatment: up to 45% patients do not experience remission with topical treatments, while evidence for systemic treatments remains scarce.2 Hydroxychloroquine (HCQ) is frequently used in daily practice as a first choice systemic therapy.3 However, little evidence is available on HCQ for ELPV.2 The aim of this study was to analyse the effectiveness and safety of HCQ in ELPV.</p

Development of a switchless sorption compressor for the cryogenic refrigeration within the METIS instrument:Part II. Experimental demonstration

Due to its vibration-free feature, sorption-based refrigeration technology has been proposed for the cryogenic cooling of the Mid-infrared E-ELT Imager and Spectrograph (METIS) instrument in the European Extremely Large Telescope. Sorption compressor is the most critical component in the METIS sorption refrigerator. A switchless sorption compressor has been designed for replacing the conventional gas-gap heat switch design. In this paper, the METIS switchless sorption compressor is validated in an experimental setup with a down-scaled version. The detailed design of the sorption compressor is introduced and the experimental setup is described. Then, the experimental procedures and results are discussed, including single-cell operation, multi-cell operation, and verification of the effects of the aluminum-foil inserts, the cycle time and the heat-sink temperature on the compressor performance. Finally, the experimental result showed good agreement with the simulations, and the deviation from the simulation to the measurement is caused by the model input inaccuracy

Development of a switchless sorption compressor for the cryogenic refrigeration within the METIS instrument:Part I. Theoretical design

Vibration-free cryogenic sorption refrigerator was proposed for the Mid-infrared E-ELT Imager and Spectrograph (METIS) instrument in the European Extremely Large Telescope. Sorption compressor is the most important part in the refrigerator due to its dominate size, cost and complexity. Generally, gas-gap heat switches are applied for efficiency consideration which is particularly essential for space applications. In METIS refrigerator as a terrestrial application, low input powers, however, should not be the major concern, whereas complexity and costs become more important as high refrigeration powers and thus large numbers of sorption cells are required. To reduce these, we developed an alternative switchless sorption-compressor design. This paper presents the theoretical design of the switchless METIS sorption compressors, including the comparison between the designs with and without heat switches. Based on the switchless design, critical parameters for the METIS sorption compressors are determined to enable further development such as mechanical design, fabrication and experimental demonstration

Baseline design of a sorption-based Joule-Thomson cooler chain for the METIS instrument in the E-ELT

METIS, the Mid-Infrared E-ELT Imager and Spectrograph, is one of the proposed instruments in E-ELT (European Extremely Large Telescope). Its infrared detectors require multiple operating temperatures below 77 K. Therefore, active coolers have to be deployed to provide sub-liquid-nitrogen (sub-LN2) temperature cooling. However, the sensitive imaging optical detecting system also demands very low levels of vibration. Thus, the University of Twente proposed a vibration-free cooling technique based on physical sorption. In this paper, we describe the baseline design of such a sorption-based Joule-Thomson cooler chain for the METIS instrument, that is able to deliver cooling powers of 0.4 W at 8 K, 1.1 W at 25 K and 1.4 W at 40 K from a 70-K heat sinking. This design is based on working fluid selection, cascading cooler stages and operating parameter optimization. Also, the performance of the resulting cooler design is analyzed

Towards a framework to evaluate the ‘total’ performance of buildings

Internationally, buildings are a major contributor to carbon emissions. Despite significant advances in the technology and construction of energy-efficient buildings, in many cases a performance gap between designed and actual performance exists. While much research has investigated the drivers of the building energy performance gap – both static and transient– there has been considerably less research into the total performance gap, defined here as performance gaps in building energy use, occupant satisfaction and Indoor Environmental Quality parameters such as thermal comfort and air quality which may impact on occupant health and wellbeing. This paper presents a meta-analysis of building performance data from buildings in the UK and China – selected due to their contrasting development environments – which illustrate the presence of and complexities of evaluating total performance gaps in both countries. The data demonstrate the need for (1) high end-use, spatial granularity and temporal resolution data for both energy and Indoor Environmental Quality, and (2) developing methodologies that allow meaningful comparisons between buildings internationally to facilitate learning from successful building design, construction methodologies and policy environments internationally. Using performance data from a UK building, a potential forward path is illustrated with the objective of developing a framework to evaluate total building performance. Practical application: While much research has examined building energy performance gaps, Indoor Environmental Quality and occupant satisfaction gaps are rarely included despite their relationship to energy. We use a meta-analysis of energy, indoor environmental quality, and occupant satisfaction data from buildings in the UK and China to illustrating the presence of and complexities of evaluating total performance gaps for buildings in the two countries, and the need for high resolution dynamic buildings data and novel methodologies for comparison between buildings across different contexts. Illustrative case studies are used to demonstrate potential future directions for evaluating ‘total’ building performance

Gla-rich protein is involved in the cross-talk between calcification and inflammation in osteoarthritis

Osteoarthritis (OA) is a whole-joint disease characterized by articular cartilage loss, tissue inflammation, abnormal bone formation and extracellular matrix (ECM) mineralization. Disease-modifying treatments are not yet available and a better understanding of osteoarthritis pathophysiology should lead to the discovery of more effective treatments. Gla-rich protein (GRP) has been proposed to act as a mineralization inhibitor and was recently shown to be associated with OA in vivo. Here, we further investigated the association of GRP with OA mineralization-inflammation processes. Using a synoviocyte and chondrocyte OA cell system, we showed that GRP expression was up-regulated following cell differentiation throughout ECM calcification, and that inflammatory stimulation with IL-1 beta results in an increased expression of COX2 and MMP13 and up-regulation of GRP. Importantly, while treatment of articular cells with gamma-carboxylated GRP inhibited ECM calcification, treatment with either GRP or GRP-coated basic calcium phosphate (BCP) crystals resulted in the down-regulation of inflammatory cytokines and mediators of inflammation, independently of its gamma-carboxylation status. Our results strengthen the calcification inhibitory function of GRP and strongly suggest GRP as a novel anti-inflammatory agent, with potential beneficial effects on the main processes responsible for osteoarthritis progression. In conclusion, GRP is a strong candidate target to develop new therapeutic approaches

Gla Rich Protein (GRP) is associated to osteoarthritis being highly accumulated in the joint tissues and synovial fluid

info:eu-repo/semantics/publishedVersio