Hydrogen adsorption and dynamics in clay minerals

A new class of hydrogen storage material (HSM), the swelling clay minerals, is introduced by the investigation of laponite, a representative smectite. Simple ion exchange allows for a diverse range of charged species to be studied as possible adsorption sites for H2 within the laponite interlayer, while a sub-monolayer of water pillars the interlayers apart by 2.85 Å, close to the kinetic diameter of H2. Neutron diffraction shows that the 001 peak, representing the clay d-spacing, is directly affected by the introduction of H2 or D2, confirming intercalation into the interlayers. Volumetric adsorption isotherms and neutron scattering show that laponites with 3 wt% H2O rapidly physisorb 0.5-1 wt% H2 at 77 K and 80 bar, with low binding enthalpies (3.40-8.74 kJ mol-1) and consequently low room temperature uptake (0.1 wt% at 100 bar). The higher structural density of clays results in lower H2 densities than MOFs and activated carbons, however some cation-exchanged forms, such as Mg and Cs, show promise for improvement having capacities of 22.8 g H2 per litre at 77K, 80 bar, intermediate between AX-21 and IRMOF-20. At low coverage, INS spectra reveal up to five adsorption sites with low rotational energy barriers (0.7-4.8 kJ mol-1), persisting up to at least 50 K. Analysis of quasielastic neutron scattering (QENS) spectra for Ca-laponite expanded with 3 wt% H2O reveals two populations of interlayer H2: one immobile up to 100 K and localised to the Ca2+ cations, while the other diffuses by jump diffusion at a rate of 1.93 0.23 Å2 ps-1 at 80 K, 60% slower than in the bulk (Dbulk = 4.90 0.84 Å2 ps-1). Arrhenius analysis gives activation energies of 188 28 K for the calcium and 120 32 K for the sodium form, comparable to the range for activated carbons. The adsorbate phase density of H2 in laponite interlayers at 40 K is 67.08 kg m-3, close to the bulk liquid density of 70.6 kg m-3. Jump lengths of 3.2 0.4 Å for Ca-laponite measured by QENS at 40 K are similar to the H2-H2 nearest neighbour distance in condensed H2 (3.79 Å). Thus data from a variety of techniques provides a coherent model for the structure and behaviour of H2 in laponite. The experimental achievement of a two-dimensional film of liquidlike H2 confined within the interlayers up to 40 K is of great interest for the field of superfluidics, since it may be possible to supercool liquid hydrogen confined in laponite interlayers below the predicted Bose-Einstein condensation temperature at 1 K

Lithium-ion battery degradation: how to model it

Predicting lithium-ion battery degradation is worth billions to the global automotive, aviation and energy storage industries, to improve performance and safety and reduce warranty liabilities. However, very few published models of battery degradation explicitly consider the interactions between more than two degradation mechanisms, and none do so within a single electrode. In this paper, the first published attempt to directly couple more than two degradation mechanisms in the negative electrode is reported. The results are used to map different pathways through the complicated path dependent and non-linear degradation space. Four degradation mechanisms are coupled in PyBaMM, an open source modelling environment uniquely developed to allow new physics to be implemented and explored quickly and easily. Crucially it is possible to see 'inside' the model and observe the consequences of the different patterns of degradation, such as loss of lithium inventory and loss of active material. For the same cell, five different pathways that can result in end-of-life have already been found, depending on how the cell is used. Such information would enable a product designer to either extend life or predict life based upon the usage pattern. However, parameterization of the degradation models remains as a major challenge, and requires the attention of the international battery community

Breaking it down: A techno-economic assessment of the impact of battery pack design on disassembly costs

The electrification of the transport sector is a critical part of the net-zero transition. The mass adoption of electric vehicles (EVs) powered by lithium-ion batteries in the coming decade will inevitably lead to a large amount of battery waste, which needs handling in a safe and environmentally friendly manner. Battery recycling is a sustainable treatment option at the battery end-of-life that supports a circular economy. However, heterogeneity in pack designs across battery manufacturers are hampering the establishment of an efficient disassembly process, hence making recycling less viable. A comprehensive techno-economic assessment of the disassembly process was conducted, which identified cost hotspots in battery pack designs and to guide design optimisation strategies that help save time and cost for end-of-life treatment. The analyses include six commercially available EV battery packs: Renault Zoe, Nissan Leaf, Tesla Model 3, Peugeot 208, BAIC and BYD Han. The BAIC and BYD battery packs exhibit lower disassembly costs (US$50.45 and US$47.41 per pack, respectively), compared to the Peugeot 208 and Nissan Leaf (US$186.35 and US$194.11 per pack, respectively). This variation in disassembly cost is due mostly to the substantial differences in number of modules and fasteners. The economic assessment suggests that full automation is required to make disassembly viable by 2040, as it could boost disassembly capacity by up to 600 %, while substantially achieving cost savings of up to US$190 M per year

Extragalactic Radio Continuum Surveys and the Transformation of Radio Astronomy

Next-generation radio surveys are about to transform radio astronomy by discovering and studying tens of millions of previously unknown radio sources. These surveys will provide new insights to understand the evolution of galaxies, measuring the evolution of the cosmic star formation rate, and rivalling traditional techniques in the measurement of fundamental cosmological parameters. By observing a new volume of observational parameter space, they are also likely to discover unexpected new phenomena. This review traces the evolution of extragalactic radio continuum surveys from the earliest days of radio astronomy to the present, and identifies the challenges that must be overcome to achieve this transformational change.Comment: To be published in Nature Astronomy 18 Sept 201

The Hot and Energetic Universe: AGN feedback in galaxy clusters and groups

Mechanical feedback via Active Galactic Nuclei (AGN) jets in the centres of galaxy groups and clusters is a crucial ingredient in current models of galaxy formation and cluster evolution. Jet feedback is believed to regulate gas cooling and thus star formation in the most massive galaxies, but a robust physical understanding of this feedback mode is currently lacking. The large collecting area, excellent spectral resolution and high spatial resolution of Athena+ will provide the breakthrough diagnostic ability necessary to develop this understanding, via: (1) the first kinematic measurements on relevant spatial scales of the hot gas in galaxy, group and cluster haloes as it absorbs the impact of AGN jets, and (2) vastly improved ability to map thermodynamic conditions on scales well-matched to the jets, lobes and gas disturbances produced by them. Athena+ will therefore determine for the first time how jet energy is dissipated and distributed in group and cluster gas, and how a feedback loop operates in group/cluster cores to regulate gas cooling and AGN fuelling. Athena+ will also establish firmly the cumulative impact of powerful radio galaxies on the evolution of baryons from the epoch of group/cluster formation to the present day

HIV seroprevalence and its effect on outcome of moderate to severe burn injuries: A Ugandan experience

\ud \ud HIV infection in a patient with burn injuries complicates the care of both the patient and the treating burn team. This study was conducted to establish the prevalence of HIV among burn patients in our setting and to compare the outcome of these patients who are HIV positive with those who are HIV negative. This was a prospective cohort study involving burn injury patients admitted to Mulago Hospital between November 2005 and February 2006. Patients were stratified into HIV positive (exposed) group and HIV-negative (unexposed) group. Data was collected using a pre-tested coded questionnaire and analyzed using SPSS statistical computer software version 11.5. Of the 130 patients included in the study, 17 (13.1%) patients tested HIV positive and this formed the study (exposed) group. The remaining 113 patients (86.9%) formed the control (unexposed) group. In the HIV positive group, females outnumbered males by a ratio of 1.4:1 and the mean age was 28.4 ± 21.5 years (range 3 months-34 years). 64.7% of HIV positive patients reported to have risk factors for HIV infection. Of these, multiple sexual partners [Odds Ratio 8.44, 95% C.I. (3.87-143.23), P = 0.011] and alcoholism [Odds Ratio 8.34, 95% C.I. (5.76-17.82), P = 0.002] were found to be independently and significantly associated with increased risk to HIV infection. The mean CD4 count for HIV positive and HIV negative patients were 394 ± 328 cells/μL and 912 ± 234 cells/μL respectively which is statistically significant (P = 0.001). There was no difference in the bacteria cultured from the wounds of HIV positive and negative patients (P = 0.322). Patients with clinical signs of sepsis had lower CD4+ counts compared to patients without sepsis (P < 0.001). ). Skin grafting was carried out in 35.3% of HIV negative patients and 29.4% of HIV positive patients with no significant difference in skin graft take and the degree of healed burn on discharge was the same (P = 0.324). There was no significant difference in hospital stay between HIV positive and negative patients (P = 0.674). The overall mortality rate was 11.5%. Using multivariate logistic regression analysis, mortality rate was found to be independently and significantly related to the age of the patient, HIV positive with stigmata of AIDS, CD4 count, inhalation injury, %TBSA and severity of burn (p-value < 0.001). HIV infection is prevalent among burn injury patients in our setting and thus presents an occupational hazard to health care workers who care for these patients. All burn health care workers in this region need to practice universal precautions in order to reduce the risk of exposure to HIV infection and post-exposure prophylaxis should be emphasized. The outcome of burn injury in HIV infected patients is dependent upon multiple variables such as age of the patient, inhalation injury and %TBSA and not the HIV status alone

The Hot and Energetic Universe: AGN feedback in galaxy clusters and groups

Mechanical feedback via Active Galactic Nuclei (AGN) jets in the centres of galaxy groups and clusters is a crucial ingredient in current models of galaxy formation and cluster evolution. Jet feedback is believed to regulate gas cooling and thus star formation in the most massive galaxies, but a robust physical understanding of this feedback mode is currently lacking. The large collecting area, excellent spectral resolution and high spatial resolution of Athena+ will provide the breakthrough diagnostic ability necessary to develop this understanding, via: (1) the first kinematic measurements on relevant spatial scales of the hot gas in galaxy, group and cluster haloes as it absorbs the impact of AGN jets, and (2) vastly improved ability to map thermodynamic conditions on scales well-matched to the jets, lobes and gas disturbances produced by them. Athena+ will therefore determine for the first time how jet energy is dissipated and distributed in group and cluster gas, and how a feedback loop operates in group/cluster cores to regulate gas cooling and AGN fuelling. Athena+ will also establish firmly the cumulative impact of powerful radio galaxies on the evolution of baryons from the epoch of group/cluster formation to the present day