Hydrogen storage using physisorption - materials demands

A survey is presented of the storage capacities of a large number of different adsorbents for hydrogen at 77 K and 1 bar. Results are evaluated to examine the feasibility and perspectives of transportable and reversible storage systems based on physisorption of hydrogen on adsorbents. It is concluded that microporous adsorbents, e.g. zeolites and activated carbons, display appreciable sorption capacities. Based on their micropore volume ( ~ 1 ml/g) carbon-based sorbents display the largest adsorption, viz. 238 ml (STP)/g, at the prevailing conditions. Optimization of sor-bent and adsorption conditions is expected to lead to adsorption of ~ 560 ml (STP)/g, close to targets set for mobile applications

Implementation and outcome of robotic liver surgery in the Netherlands: a nationwide analysis

Objective:To determine the nationwide implementation and surgical outcome of minor and major robotic liver surgery (RLS) and assess the first phase of implementation of RLS during the learning curve. Background:RLS may be a valuable alternative to laparoscopic liver surgery. Nationwide population-based studies with data on implementation and outcome of RLS are lacking. Methods:Multicenter retrospective cohort study including consecutive patients who underwent RLS for all indications in 9 Dutch centers (August 2014-March 2021). Data on all liver resections were obtained from the mandatory nationwide Dutch Hepato Biliary Audit (DHBA) including data from all 27 centers for liver surgery in the Netherlands. Outcomes were stratified for minor, technically major, and anatomically major RLS. Learning curve effect was assessed using cumulative sum analysis for blood loss. Results:Of 9437 liver resections, 400 were RLS (4.2%) procedures including 207 minor (52.2%), 141 technically major (35.3%), and 52 anatomically major (13%). The nationwide use of RLS increased from 0.2% in 2014 to 11.9% in 2020. The proportion of RLS among all minimally invasive liver resections increased from 2% to 28%. Median blood loss was 150 mL (interquartile range 50-350 mL] and the conversion rate 6.3% (n=25). The rate of Clavien-Dindo grade >= III complications was 7.0% (n=27), median length of hospital stay 4 days (interquartile range 2-5) and 30-day/in-hospital mortality 0.8% (n=3). The R0 resection rate was 83.2% (n=263). Cumulative sum analysis for blood loss found a learning curve of at least 33 major RLS procedures. Conclusions:The nationwide use of RLS in the Netherlands has increased rapidly with currently one-tenth of all liver resections and one-fourth of all minimally invasive liver resections being performed robotically. Although surgical outcomes of RLS in selected patient seem favorable, future prospective studies should determine its added value.Surgical oncolog

Spotlight on the region analytical contributions on regional development

Regional science has, in its great history since the 1950s, made a decisive contribution to a better scientific understanding of spatial development issues and dynamics and to a more effective implementation of knowledge-based regional policy in many countries of the world, in both developed and developing nations on our planet. This special issue of the annals of regional science, titled "Spotlight on the Region", celebrates the scholarly importance and impact of the late Roger Stough on regional science. The issue is comprised of fourteen self-standing on regional and urban development and highlights the critical importance of regional and urban dimensions in sustainable development. They confirm once more the seminal significance of the contributions of one of the great giants in regional science, Roger Stough

Hub premiums in European civil aviation

We investigate the practice of carriers that charge higher fares for flights leaving from their hub. We analyze this phenomenon by relating fares to distance, using the main leg of intercontinental flights for scaling purposes. Our results indicate that the practice of a mark up on flights originating from or going to hubs is not typical for the US situation. At least some European carriers charge significant premiums for direct flights from their hubs. We find that at least part of these premiums can be attributed to market power. Policy measures should be aimed at reduction of market power and consumer protection. Furthermore, the existence of hub premiums should be taken into account in regional hub policies. © 2001 Elsevier Science Ltd. All rights reserved

Infrastructure and the international export performance of Turkish regions

We estimate the Anderson and van Wincoop model of trade by using the data on the bilateral export flows from 26 Turkish regions to 180 countries for the years 2002 through to 2010. Regional transportation and communication infrastructure capacity, the positioning of point infrastructure in a region, and geography are explicitly accounted for. Our results highlight that land infrastructure, air transport capacity, and private maritime infrastructure presence, together with the distance of regional economies to exit nodes such as ports and airports, are important determinants of export performance. Based on our preferred regression where multilateral resistance terms are accounted for, we estimate that increases in the current land infrastructure, air transport capacity, and number of private ports of 1 per cent increases exports approximately by 0.38 per cent, 0.14 per cent, and 0.045 per cent respectively. Keywords: Infrastructure; trade; regions; transportation cost

Measuring competition in civil aviation

Markets in civil aviation are characterized by large differences in the level of competition, both between time periods as between regions. To measure competition, several indicators are available, such as the number of competitors, the C4-index and the Herfindahl index. We use these measures in simulations of events that influence the level of competition, such as growing market shares, entry and merger. We find that there are events where different measures lead to different outcomes, not only in magnitude but also in sign. Competition indicators should be used with caution and attention should be devoted to the definition of the market and the importance of imperfect substitutes. The simultaneous use of several indicators, along with economic intuition and common sense reduces the risks involved. © 2002 Elsevier Science Ltd. All rights reserved