High density hydrogen films adsorbed in engineered carbon nanospaces

International audienceThe search for sustainable automotive fuels has driven numerous studies of sorption-based hydrogen storage for hydrogen fuel cell vehicles. Storage by adsorption is fully reversible, achieves fast fill/discharge demands by simple pressurization/depressurization, and operates at much lower pressure than compressed hydrogen and at much less demanding temperatures than liquid hydrogen. In support of the DOE 2020 storage capacity target of 40 g hydrogen/L system, we have investigated the density of the adsorbed hydrogen films in a variety of porous carbons synthesized at the University of Missouri. The investigation decomposes storage into a high-density adsorbed film and low-density non-adsorbed gas and determines the fraction of pore volume occupied by the two phases.We find exceptionally dense H2 films at liquid nitrogen temperature, 77 K. Saturated film densities are 100-120 g/L across all samples at pressures as low as 35-70 bar. This is 1.4-1.7 times the density of liquid hydrogen at its normal boiling point, 71 g/L (20 K). Experimental film thicknesses are 0.30-0.32 nm, and fractions of total pore volume filled with high-density film are 0.25-0.53. Thus high storage capacities, well in excess of the DOE target and even in excess of liquid hydrogen, can be achieved at 77 K in appropriately engineered nanoporous carbons.The dense films occur at a temperature more than twice the liquid-gas critical temperature of hydrogen, 33 K, above which no bulk liquid exists at any pressure. The high-density film above 33 K does not contradict the non-existence of bulk liquid: the film is not a bulk, 3D phase, but a monomolecular 2D phase. Monte Carlo simulations confirm the observed high density and small film thickness. The film density and volume remain constant up to gas densities ~80% of the film density. A discussion in terms of competing forces acting on adsorbed molecules will be given

Supercritical condensation of hydrogen at 77 K in engineered carbon nanospaces

International audienceIn response to the DOE’s quest for sorption-based hydrogen storage materials that meet the 2017 volumetric storage capacity target of 40 g hydrogen/L systemfor light-duty fuel cell vehicles, we have undertaken a large-scale experimental investigation of intrapore hydrogen densities—total mass of hydrogen stored pervolume of pore space—in high-surface-area carbons with variable nanopore structure. Intrapore density includes the adsorbed film and non-adsorbed gas, andconsequently lies between the density of bulk hydrogen gas and the density of the adsorbed film at the respective pressure and temperature. Intrapore densitiesup to 85 g/L were observed at 77 K and 200 bar, well in excess of 71 g/L, the density of liquid hydrogen at 20 K and 1 bar, and well above the liquid-gas criticalpoint of hydrogen, 33 K (“supercritical condensation”). Densities of the adsorbed film at saturation were found to vary between 100 and 120 g/L, which is over50% higher than in liquid hydrogen. These are exceptionally high film densities. They are consistent with the finding that, even in carbons with pore widthsexclusively centered at 7 Å (“ultramicroporous carbon”), the ratio of the saturated film volume to total pore volume is only between 0.5 and 0.6, i.e., that the filmdoes not fill the pores. We established that the saturated film is a liquid by demonstrating that the film has a constant volume as a function of gas pressure over awide pressure range (incompressible fluid). From the experimental film volume and surface area, we infer that the saturated film has a thickness of 3.0-3.5 Å at 77K and thus amounts to a monolayer, consistent with that supercritical adsorption does not allow for multilayer films. Implications for experimental determination ofenthalpies of adsorption (isosteric heats) will be presented.Samples have exceptionally low void fractions (0.49-0.70), maxima of gravimetric excess adsorption at exceptionally low pressures (~25 bar), and exceptionallyhigh binding energies (8-10 kJ/mol) consistent with deep potential wells in narrow, 7-Å pores. The resulting saturated film densities outperform previous saturatedhydrogen film densities, 51-69 g/L, in metal-organic frameworks at 50-55 K, by as much as 20% at a 40-50% higher temperature. The exceptionally high filmdensities in our investigation are attributed to the strong hydrogen-carbon adsorption potential in narrow pores. Grand canonical Monte Carlo simulations ofadsorption in slit-shaped pores of variable width (variable binding energy) will be presented to examine the dependence of the film density as a function of bindingenergy and compare computed and experimental film densities, and likewise intrapore densities. In slit-shaped pores, the adsorbed film may be viewed astwo-dimensional liquid with a critical temperature way above 33 K, while in the direction perpendicular to the graphitic planes the film remains a supercriticalmonolayer with critical temperature of 33 K.This material is based on work supported by the U.S. Department of Energy under contracts DE-FG36-08GO18142 and DE-FG02-07ER46411

Integration of gender-specific contents into the medical education at the Charité - Universitätsmedizin Berlin

Introduction: Knowledge derived from gender specific research is more and more integrated into the medical education. In Germany this process is developing with a certain delay compared to other Anglo-Saxon or Scandinavian countries. Our survey examines for the first time to what extend gender specific aspects have been integrated into the medical education at the Charite Universitaetsmedizin Berlin. Material and Methods: Topics like gender specific learning objectives and their implementation in the own field were evaluated by means of a standardized questionnaire, differentiated for professors, medical teachers and course coordinators as well as for sex in qualitative and quantitative categories. Results: 30 different fields of medicine took part in this study and revealed a number of important topics with gender specific differences. These contents are integrated into the medical education with relatively simple methods by 70% of the participating professors and medical teachers. In general there is only little interest in spending time for further qualification or the development of a curriculum for the field of gender medicine. Female participants of this study were significantly more interested in gender medicine aspects (p=0,017 development of the medical curriculum). Conclusion: This study underlines the need for official learning objectives containing gender differences during the medical education at the Charite Berlin. A great number of the teaching staff reveals a positive attitude towards these contents and integrates a lot of them. These efforts should be supported by more gender specific teaching material and personal investment into the curricular development.Zielsetzung: Die Erkenntnisse der Geschlechterforschung finden zunehmend Eingang in die medizinische Ausbildung von ÄrztInnen. Dabei steht Deutschland verglichen mit vielen englischsprachigen und nordeuropäischen Ländern noch am Anfang einer Entwicklung. Die vorgelegte Bestandsaufnahme untersucht, welchen Stellenwert geschlechterspezifische Fragestellungen in der Lehre an der Charité Universitätsmedizin Berlin haben. Methodik: Mit Hilfe eines standardisierten Fragebogens wurden verschiedene Themenbereiche wie geschlechtsspezifische Lernziele und die Umsetzung im eigenen Fach quantitativ und qualitativ für ProfessorInnen, DozentInnen und LehrkoordinatorInnen sowie nach Geschlecht erfasst. Ergebnisse: 30 verschiedene Fächer haben an der Bestandsaufnahme teilgenommen und dabei eine Reihe von Themenkomplexen mit geschlechterspezifischen Unterschieden zusammengetragen. Bisher werden solche Themen nur mit relativ einfachen Mitteln in der Lehre durch etwa 70% der angeschriebenen ProfessorInnen und DozentInnen umgesetzt. Insgesamt besteht aber wenig Interesse der Lehrenden an zusätzlichem Zeitaufwand für Qualifizierung oder Curriculumsentwicklung in diesem Bereich. Die weiblichen Teilnehmenden standen dem Thema 'Geschlechterunterschiede in der Medizin' signifikant offener gegenüber (p=0,017 Interesse an Curriculumsentwicklung). Schlussfolgerung: Es gibt einen Bedarf an formulierten Lernzielen für Themenkomplexe mit Geschlechteraspekt im Curriculum des Medizinstudiums an der Charité Berlin. Eine Vielzahl von Lehrenden steht diesen Themenkomplexen offen gegenüber, unterrichtet solche Inhalte bereits und sollte in der Curriculumsentwicklung sowie mit Material bei der Umsetzung im Rahmen ihrer Lehrtätigkeiten unterstützt werden

An integrated patient-centric approach for situated research on total hip replacement: ESTHER

Homecare is believed to alleviate the care responsibilities that professionals and health institutions are facing due to increasing need for care that our current society demands. Relying on the emergence of technological innovations homecare could empower patients to undertake a more active role in the care practice. Understanding the value of technologies to support patients’ awareness and reflection of their own progress is argued as an important step to design appropriate mechanisms that fit patients’ needs. This chapter discusses an integrated patient-centric approach to design homecare technologies considering patients’ personal experiences and social context as crucial aspects when providing care support. This approach proposes the development of in-situ methods and tools to provide a holistic view of patients care experience through the design of interventions in the context of use. The development of ESTHER (Experience Sampling for Total Hip Replacement) is presented to illustrate the benefits and challenges of conducting in-situ research by supporting the collection of physical activity and emotional states in order for patients to self-monitor and self-reflect on the progress of their recovery. The transition from open and simple interventions to more complex and specific ones opens the discussion of the role of technology to introduce new practices that uncover richer experiences by influencing patient’s care activities via self-reporting and self-reflecting mechanisms. The gradual introduction of technologies to uncover from general to more specific experiences it does not only address research needs, more important it brings an understanding on the acceptance of technologies in patients’ care practices. The consequence is a new generation of research to application tools that bring a closer understanding of patients’ experiences and context to inform the design of supportive homecare technologies that embrace a more active role of patients