Mg–Ti nanoparticles with superior kinetics for hydrogen storage

open5siAcknowledgements The assistance of F. Corticelli and V. Morandi (IMM-CNR, Bologna) during FE-SEM observations is gratefully acknowledged. Part of this work was supported by the COST Action MP1103 “Nanostructured materials for solid-state hydrogen storage”. We are grateful to the beamline I711 at MAXlab, Lund, Sweden for the provision of beamtime.Mg nanoparticles (NPs) with addition of Ti catalysts were synthesised by inert gas condensation and in situ hydrogenation at 150 °C. The NPs size and composition were systematically investigated by scanning electron microscopy, energy dispersive X-ray spectroscopy and powder X-ray diffraction (PXD), while time resolved in situ synchrotron radiation-PXD was used to monitor the mechanism for hydrogen uptake and release at 280 °C. The Mg–Ti NPs reveal activation energies of 68 kJ mol−1 for absorption and 78 kJ mol−1 for desorption by isothermal kinetics analysis, similar to the lowest values reported in the literature for MgH2 using Nb2O5 as a catalyst. Hence, hydrogen desorption (pdes = 8 mbar) and absorption (pabs = 260 mbar) is achieved at 200 °C in ∼2000 s, while keeping 5.3 wt% storage capacity. Thermodynamic data extracted from van ’t Hoff plots reveal unchanged values compared to bulk MgH2. Therefore, the improved hydrogen storage performances are assigned to the enhanced kinetics only.openCalizzi, Marco; Chericoni, Domizia; Jepsen, Lars H.; Jensen, Torben R.; Pasquini, LucaCalizzi, Marco; Chericoni, Domizia; Jepsen, Lars H.; Jensen, Torben R.; Pasquini, Luc

Boron-nitrogen based hydrides and reactive composites for hydrogen storage

Hydrogen forms chemical compounds with most other elements and forms a variety of different chemical bonds. This fascinating chemistry of hydrogen has continuously provided new materials and composites with new prospects for rational design and the tailoring of properties. This review highlights a range of new boron and nitrogen based hydrides and illustrates how hydrogen release and uptake properties can be improved. © 2014 Elsevier Ltd

Complex hydrides for hydrogen storage - New perspectives

Since the 1970s, hydrogen has been considered as a possible energy carrier for the storage of renewable energy. The main focus has been on addressing the ultimate challenge: eveloping an environmentally friendly successor for gasoline. This very ambitious goal has not yet been fully reached, as discussed in this review, but a range of new lightweight hydrogen-ontaining materials has been discovered with fascinating properties. State-of-the-art and future perspectives for hydrogen-containing solids will be discussed, with a focus on metal borohydrides, which reveal significant structural flexibility and may have a range of new interesting properties combined with very high hydrogen densities

Mortality among Patients with Cleared Hepatitis C Virus Infection Compared to the General Population: A Danish Nationwide Cohort Study

BACKGROUND: The increased mortality in HCV-infected individuals partly stems from viral damage to the liver and partly from risk-taking behaviours. We examined mortality in patients who cleared their HCV-infection, comparing it to that of the general population. We also addressed the question whether prognosis differed according to age, substance abuse (alcohol abuse and injection drug use) and comorbidity. METHODOLOGY/PRINCIPAL FINDINGS: Patients with cleared HCV-infection were categorized into one of 8 groups according to age (20-39 years or 40-69 years) and patient characteristics (no substance abuse/no comorbidity; substance abuse/no comorbidity; no substance abuse/comorbidity; and substance abuse/comorbidity). For each patient, 4 age- and gender-matched individuals without substance abuse or comorbidity were selected from the general population, comprising a total of 8 comparison cohorts. We analyzed 10-year survival and used stratified Cox Regression analysis to compute mortality rate ratios (MRRs), comparing mortality between the 8 patient groups and the comparison cohorts, adjusting for personal income. Among patients without substance abuse or comorbidity, those aged 40-69 years had the same mortality as the comparison cohort (10-year survival: 95% (95% confidence interval [CI]: 93%-97%), MRR: 1.3 (95% CI: 0.8-2.3)), whereas those aged 20-39 years had higher mortality than the comparison cohort (10-year survival: 93% versus 99%, MRR: 5.7 (95% CI: 2.3-14.0). For both age categories, substance abuse and comorbidity decreased survival and increased MRRs. Patients aged 40-69 years with substance abuse and comorbidity suffered from substantial mortality (MRR: 12.5 (95% CI: 5.1-30.6)). CONCLUSIONS: Mortality in patients aged 40-69 years with cleared HCV-infection is comparable to individuals without HCV, provided they have no substance abuse or comorbidity. Any substance abuse and/or comorbidity not captured in the registries used for our study could explain the increased mortality in patients aged 20-39 years without documented substance abuse or comorbidity

Optimal Swimming Speed in Head Currents and Effects on Distance Movement of Winter-Migrating Fish

Migration is a commonly described phenomenon in nature that is often caused by spatial and temporal differences in habitat quality. However, as migration requires energy, the timing of migration may depend not only on differences in habitat quality, but also on temporal variation in migration costs. Such variation can, for instance, arise from changes in wind or current velocity for migrating birds and fish, respectively. Whereas behavioural responses of birds to such changing environmental conditions have been relatively well described, this is not the case for fish, although fish migrations are both ecologically and economically important. We here use passive and active telemetry to study how winter migrating roach regulate swimming speed and distance travelled per day in response to variations in head current velocity. Furthermore, we provide theoretical predictions on optimal swimming speeds in head currents and relate these to our empirical results. We show that fish migrate farther on days with low current velocity, but travel at a greater ground speed on days with high current velocity. The latter result agrees with our predictions on optimal swimming speed in head currents, but disagrees with previously reported predictions suggesting that fish ground speed should not change with head current velocity. We suggest that this difference is due to different assumptions on fish swimming energetics. We conclude that fish are able to adjust both swimming speed and timing of swimming activity during migration to changes in head current velocity in order to minimize energy use

A lake as a microcosm: reflections on developments in aquatic ecology

In the present study, we aim at relating Forbes' remarkable paper on "The lake as a microcosm", published 125 years ago, to the present status of knowledge in our own research group. Hence, we relate the observations Forbes made to our own microcosm, Lake Krankesjon in southern Sweden, that has been intensively studied by several research groups for more than three decades. Specifically, we focus on the question: Have we made any significant progress or did Forbes and colleagues blaze the trail through the unknown wilderness and we are mainly paving that intellectual road? We conclude that lakes are more isolated than many other biomes, but have, indeed, many extensions, for example, input from the catchment, fishing and fish migration. We also conclude that irrespective of whether lakes should be viewed as microcosms or not, the paper by Forbes has been exceptionally influential and still is, especially since it touches upon almost all aspects of the lake ecosystem, from individual behaviour to food web interactions and environmental issues. Therefore, there is no doubt that even if 125 years have passed, Forbes' paper still is a source of inspiration and deserves to be read. Hence, although aquatic ecology has made considerable progress over the latest century, Forbes might be viewed as one of the major pioneers and visionary scientists of limnology