Vibration isolation with high thermal conductance for a cryogen-free dilution refrigerator

We present the design and implementation of a mechanical low-pass filter vibration isolation used to reduce the vibrational noise in a cryogen-free dilution refrigerator operated at 10 mK, intended for scanning probe techniques. We discuss the design guidelines necessary to meet the competing requirements of having a low mechanical stiffness in combination with a high thermal conductance. We demonstrate the effectiveness of our approach by measuring the vibrational noise levels of an ultrasoft mechanical resonator positioned above a SQUID. Starting from a cryostat base temperature of 8 mK, the vibration isolation can be cooled to 10.5 mK, with a cooling power of 113 $\mu$W at 100 mK. We use the low vibrations and low temperature to demonstrate an effective cantilever temperature of less than 20 mK. This results in a force sensitivity of less than 500 zN/$\sqrt{\mathrm{Hz}}$, and an integrated frequency noise as low as 0.4 mHz in a 1 Hz measurement bandwidth

Present and future cost of alkaline and PEM electrolyser stacks

We use complementary bottom-up and top-down approaches to assess the current cost of AE and PEM stacks and how the costs are expected to come down by 2030. The total AE and PEM stack cost reduce from a range of 242–388 €/kW and 384–1071 €/kW in 2020 to 52–79 €/kW and 63–234 €/kW in 2030 respectively. The main drivers of these cost reductions are an increased current density and a reduction and/or replacement of expensive materials with cheaper alternatives. To a lesser extent, manufacturing and labor costs reduction is expected due to mass manufacturing at a GW scale. The total cost decrease is less prominent for AE than PEM due to AE's maturity. The uncertainty range for PEM stacks is due to the low TRL associated with the advanced design PEM stack.</p

Present and future cost of alkaline and PEM electrolyser stacks

We use complementary bottom-up and top-down approaches to assess the current cost of AE and PEM stacks and how the costs are expected to come down by 2030. The total AE and PEM stack cost reduce from a range of 242–388 €/kW and 384–1071 €/kW in 2020 to 52–79 €/kW and 63–234 €/kW in 2030 respectively. The main drivers of these cost reductions are an increased current density and a reduction and/or replacement of expensive materials with cheaper alternatives. To a lesser extent, manufacturing and labor costs reduction is expected due to mass manufacturing at a GW scale. The total cost decrease is less prominent for AE than PEM due to AE's maturity. The uncertainty range for PEM stacks is due to the low TRL associated with the advanced design PEM stack.</p

Comparison between three different LCIA methods for aquatic ecotoxicity and a product environmental risk assessment: Insights from a Detergent Case Study within OMNIITOX

Background and Objective: In the OMNIITOX project 11 partners have the common objective to improve environmental management tools for the assessment of (eco)toxicological impacts. The detergent case study aims at: i) comparing three Procter &c Gamble laundry detergent forms (Regular Powder-RP, Compact Powder-CP and Compact Liquid-CL) regarding their potential impacts on aquatic ecotoxicity, ii) providing insights into the differences between various Life Cycle Impact Assessment (LCIA) methods with respect to data needs and results and iii) comparing the results from Life Cycle Assessment (LCA) with results from an Environmental Risk Assessment (ERA). Material and Methods: The LCIA has been conducted with EDIP97 (chronic aquatic ecotoxicity) [1], USES-LCA (freshwater and marine water aquatic ecotoxicity, sometimes referred to as CML2001) [2, 3] and IMPACT 2002 (covering freshwater aquatic ecotoxicity) [4]. The comparative product ERA is based on the EU Ecolabel approach for detergents [5] and EUSES [6], which is based on the Technical Guidance Document (TGD) of the EU on Environmental Risk Assessment (ERA) of chemicals [7]. Apart from the Eco-label approach, all calculations are based on the same set of physico-chemical and toxicological effect data to enable a better comparison of the methodological differences. For the same reason, the system boundaries were kept the same in all cases, focusing on emissions into water at the disposal stage. Results and Discussion: Significant differences between the LCIA methods with respect to data needs and results were identified. Most LCIA methods for freshwater ecotoxicity and the ERA see the compact and regular powders as similar, followed by compact liquid. IMPACT 2002 (for freshwater) suggests the liquid is equally as good as the compact powder, while the regular powder comes out worse by a factor of 2. USES-LCA for marine water shows a very different picture seeing the compact liquid as the clear winner over the powders, with the regular powder the least favourable option. Even the LCIA methods which result in die same product ranking, e.g. EDIP97 chronic aquatic ecotoxicity and USES-LCA freshwater ecotoxicity, significantly differ in terms of most contributing substances. Whereas, according to IMPACT 2002 and USES-LCA marine water, results are entirely dominated by inorganic substances, the other LCIA methods and the ERA assign a key role to surfactants. Deviating results are mainly due to differences in the fate and exposure modelling and, to a lesser extent, to differences in the toxicological effect calculations. Only IMPACT 2002 calculates the effects based on a mean value approach, whereas all other LCIA methods and the ERA tend to prefer a PNEC-based approach. In a comparative context like LCA the OMNIITOX project has taken the decision for a combined mean and PNEC-based approach, as it better represents the ‘average' toxicity while still taking into account more sensitive species. However, the main reason for deviating results remains in the calculation of the residence time of emissions in the water compartments. Conclusion and Outlook: The situation that different LCIA methods result in different answers to the question concerning which detergent type is to be preferred regarding the impact category aquatic ecotoxicity is not satisfactory, unless explicit reasons for the differences are identifiable. This can hamper practical decision support, as LCA practitioners usually will not be in a position to choose the 'right' LCIA method for their specific case. This puts a challenge to the entire OMNIITOX project to develop a method, which finds common ground regarding fate, exposure and effect modelling to overcome the current situa-tion of diverging results and to reflect most realistic condition

Enhancing discharge decision-making through continuous monitoring in an acute admission ward:a randomized controlled trial

In Acute Admission Wards, vital signs are commonly measured only intermittently. This may result in failure to detect early signs of patient deterioration and impede timely identification of patient stability, ultimately leading to prolonged stays and avoidable hospital admissions. Therefore, continuous vital sign monitoring may improve hospital efficacy. The objective of this randomized controlled trial was to evaluate the effect of continuous monitoring on the proportion of patients safely discharged home directly from an Acute Admission Ward. Patients were randomized to either the control group, which received usual care, or the sensor group, which additionally received continuous monitoring using a wearable sensor. The continuous measurements could be considered in discharge decision-making by physicians during the daily bedside rounds. Safe discharge was defined as no unplanned readmissions, emergency department revisits or deaths, within 30 days after discharge. Additionally, length of stay, the number of Intensive Care Unit admissions and Rapid Response Team calls were assessed. In total, 400 patients were randomized, of which 394 completed follow-up, with 196 assigned to the sensor group and 198 to the control group. The proportion of patients safely discharged home was 33.2% in the sensor group and 30.8% in the control group (p = 0.62). No significant differences were observed in secondary outcomes. The trial was terminated prematurely due to futility. In conclusion, continuous monitoring did not have an effect on the proportion of patients safely discharged from an Acute Admission Ward. Implementation challenges of continuous monitoring may have contributed to the lack of effect observed. Trial registration: https://clinicaltrials.gov/ct2/show/NCT05181111. Registered: January 6, 2022.</p

Prospective LCA of alkaline and PEM electrolyser systems

This prospective life cycle assessment (LCA) compares the environmental impacts of alkaline electrolyser (AE) and proton exchange membrane (PEM) electrolyser systems for green hydrogen production with a special focus on the stack components. The study evaluates both baseline and near-future advanced designs, considering cradle-to-gate life cycle from material production to operation. The electricity source followed by the stacks are identified as major contributors to environmental impacts. No clear winner emerges between AE and PEM in relation to environmental impacts. The advanced designs show a reduced impact in most categories compared to baseline designs which can mainly be attributed to the increased current density. Advanced green hydrogen production technologies outperform grey and blue hydrogen production technologies in all impact categories, except for minerals and metals resource use due to rare earth metals in the stacks. Next to increasing current density, decreasing minimal load requirements. improving sustainable mining practices (including waste treatment) and low carbon intensity steel production routes can enhance the environmental performance of electrolyser systems, aiding the transition to sustainable hydrogen production

Stakeholder perspectives on the scale-up of green hydrogen and electrolyzers

Green hydrogen is a promising alternative to fossil fuels. However, current production capacities for electrolyzers and green hydrogen are not in line with national political goals and projected demand. Considering these issues, we conducted semi-structured interviews to determine the narratives of different stakeholders during this transformation as well as challenges and opportunities for the green hydrogen value chain. We interviewed eight experts with different roles along the green hydrogen value chain, ranging from producers and consumers of green hydrogen to electrolyzer manufacturers and consultants as well as experts from the political sphere. Most experts see the government as necessary for scale-up, by setting national capacity targets, policy support and providing subsidies. However, the experts also accuse the governments of delaying development through overregulation and long implementation times for regulations. The main challenges that were identified are the current lack of renewable electricity and demand for green hydrogen. Demand for green hydrogen is influenced by supply costs, which partly depend on prices for electrolyzers. However, one key takeaway of the interviews is the skeptical assessments by the experts on the currently discussed estimates for price reduction potential of electrolyzers. While demand, supply, and prices are all factors that influence each other, they result in feedback loops in investment decisions for the energy and manufacturing industries. A second key takeaway is, that according to the experts, current investment decisions in new production capacities are not solely dependent on short-term financial gains, but also based on expected first mover advantages. These include experience and market share which are seen as factors for opportunities for future financial gains. Summarized, the results present several challenges and opportunities for green hydrogen and electrolyzers, and how to address them effectively. These insights contribute to a deeper understanding of the dynamics of the emerging green hydrogen value chain

Detailed modelling of basic industry and material flows in a national energy system optimization model

National energy system models are often ill-equipped to examine the interconnections between material and energy systems, and the tradeoffs between energy or material use of limited resources are left unaddressed. An adapted energy system model (IESA-Opt) combined with a revised dataset, including 22 new material flows, 33 new processes, and revisions to existing processes, broadens the range of solutions. We show that including additional detail in the major energy-intensive material production sectors has a significant impact on the results of a net-zero emissions scenario for the Netherlands. The result is different optimal technology investment pathways compared to the previous scenario, and total system costs that are 0.8 % lower over the time horizon. The results highlight the value of explicitly including detail on energy-intensive material and industry in analyzing interactions between sectors – particularly waste, chemicals and fuel production – and points to improvements in energy system modelling for industry

The effect of klapskate hinge position on push-off performance: a simulation study

klapskate in speed skating confronts skaters with the question of how to adjust the position of the hinge in order to maximize performance. The purpose of this study was to reveal the constraint that klapskate hinge position imposes on push-off performance in speed skating. Method: For this purpose, a model of the musculoskeletal system was designed to simulate a simplified, two-dimensional skating push off. To capture the essence of a skating push off, this model performed a one-leg vertical jump, from a frictionless surface, while keeping its trunk horizontally. In this model, klapskate hinge position was varied by varying the length of the foot segment between 115 and 300 mm. With each foot length, an optimal control solution was found that resulted in the maximal amount of vertical kinetic and potential energy of the body’s center of mass at take off (Weff). Results: Foot length was shown to considerably affect push-off performance. Maximal Weff was obtained with a foot length of 185 mm and decreased by approximately 25 % at either foot length of 115 mm and 300 mm. The reason for this decrease was that foot length affected the onset and control of foot rotation. This resulted in a distortion of the pattern of leg segment rotations and affected muscle work (Wmus) and the efficacy ratio (Weff/Wmus) of the entire leg system. Conclusion: Despite its simplicity, the model very well described and explained the effects of klapskate hinge position on push off performance that have been observed in speed-skating experiments. The simplicity of the model, however, does not allow quantitative analyses of optimal klapskate hinge position for speed-skating practice. Key Words: SPEED SKATING, SPORTS EQUIPMENT, LOCOMOTION, MUSCULO-SKELETAL MODEL, BIOMECHANICS Klapskates have become the custom equipment inspeed skating. In contrast to the conventionalskates, in which the shoe is rigidly fixed to th