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

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

Gebruikservaringen met het Biofix-systeem op het Proefstation

In dit artikel worden de gebruikservaringen met het Biofix-systeem gedurende de aanloopperiode beschreven. Het aantal wisselingen bij de voertrog en/of agressieve interacties tussen zeugen tijdens het voeren is te hoog. Controle tijdens het voeren is nodig, vooral bij de nieuw ingezette groepe

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

Small portion sizes in worksite cafeterias: do they help consumers to reduce their food intake?

Background:Environmental interventions directed at portion size might help consumers to reduce their food intake.Objective:To assess whether offering a smaller hot meal, in addition to the existing size, stimulates people to replace their large meal with a smaller meal.Design:Longitudinal randomized controlled trial assessing the impact of introducing small portion sizes and pricing strategies on consumer choices.Setting/participants:In all, 25 worksite cafeterias and a panel consisting of 308 consumers (mean age39.18 years, 50% women).Intervention:A small portion size of hot meals was offered in addition to the existing size. The meals were either proportionally priced (that is, the price per gram was comparable regardless of the size) or value size pricing was employed.Main outcome measures:Daily sales of small and the total number of meals, consumers self-reported compensation behavior and frequency of purchasing small meals.Results:The ratio of small meals sales in relation to large meals sales was 10.2%. No effect of proportional pricing was found B0.11 (0.33), P0.74, confidence interval (CI): 0.76 to 0.54). The consumer data indicated that 19.5% of the participants who had selected a small meal often-to-always purchased more products than usual in the worksite cafeteria. Small meal purchases were negatively related to being male (B0.85 (0.20), P0.00, CI: 1.24 to 0.46, n178).Conclusion:When offering a small meal in addition to the existing size, a percentage of consumers that is considered reasonable were inclined to replace the large meal with the small meal. Proportional prices did not have an additional effect. The possible occurrence of compensation behavior is an issue that merits further attention. © 2011 Macmillan Publishers Limited All rights reserved

Predictable and robust performance of a Bi-2223 superconducting coil for compact isochronous cyclotrons

The development of ever smaller medical particle accelerators is motivated by a desire to make proton therapy accessible to more patients. Reducing the footprint of particle accelerators and subsequently proton therapy facilities allows for cheaper and broader usage of proton therapy. By employing superconducting technologies for field shaping, the size of particle accelerators can be reduced further below what is possible with saturated iron. This article discusses experiments on a first-of-its-kind double pancake (DP), and an assembly of six DP coils, designed to be used as a so-called ‘flutter coil’ for a compact isochronous cyclotron for proton therapy, fabricated from high-temperature superconducting (HTS) Bi 2 − x Pbx Sr2Ca2Cu3Oy (Bi-2223) tape. The coils were mounted under pre-stress within a stainless-steel structure to maintain mechanical stability during the experiments. The critical current as a function of the temperature of both coils was measured in a conduction-cooled setup. A model describing the coils, based on tape data, was created and revealed that the measurements were in excellent agreement with the predictions. Additional experiments were performed to study the quench and thermal runaway behaviour of the HTS coils, determining whether such coils can be protected against fault scenarios, using realistic quench-detection levels and discharge extraction-rates. These experiments demonstrate that the coils are very robust and can be well protected against quenches and thermal-runaway events using common quench-protection measures with realistic parameters.</p