The fingerprint of the summer 2018 drought in Europe on ground-based atmospheric CO2 measurements

During the summer of 2018, a widespread drought developed over Northern and Central Europe. The increase in temperature and the reduction of soil moisture have influenced carbon dioxide (CO₂) exchange between the atmosphere and terrestrial ecosystems in various ways, such as a reduction of photosynthesis, changes in ecosystem respiration, or allowing more frequent fires. In this study, we characterize the resulting perturbation of the atmospheric CO₂ seasonal cycles. 2018 has a good coverage of European regions affected by drought, allowing the investigation of how ecosystem flux anomalies impacted spatial CO₂ gradients between stations. This density of stations is unprecedented compared to previous drought events in 2003 and 2015, particularly thanks to the deployment of the Integrated Carbon Observation System (ICOS) network of atmospheric greenhouse gas monitoring stations in recent years. Seasonal CO₂ cycles from 48 European stations were available for 2017 and 2018. Earlier data were retrieved for comparison from international databases or national networks. Here, we show that the usual summer minimum in CO₂ due to the surface carbon uptake was reduced by 1.4 ppm in 2018 for the 10 stations located in the area most affected by the temperature anomaly, mostly in Northern Europe. Notwithstanding, the CO₂ transition phases before and after July were slower in 2018 compared to 2017, suggesting an extension of the growing season, with either continued CO₂ uptake by photosynthesis and/or a reduction in respiration driven by the depletion of substrate for respiration inherited from the previous months due to the drought. For stations with sufficiently long time series, the CO₂ anomaly observed in 2018 was compared to previous European droughts in 2003 and 2015. Considering the areas most affected by the temperature anomalies, we found a higher CO₂ anomaly in 2003 (+3 ppm averaged over 4 sites), and a smaller anomaly in 2015 (+1 ppm averaged over 11 sites) compared to 2018. This article is part of the theme issue 'Impacts of the 2018 severe drought and heatwave in Europe: from site to continental scale'.

Impact of the Mechanical Properties of a Functionalized Cross-Linked Binder on the Longevity of Li-S Batteries

One of the very challenging aspects of Li-S battery development is the fabrication of a sulfur electrode with high areal loading using conventional Li-ion binders. Herein, we report a new multifunctional polymeric binder, synthesized by the free-radical cross-linking polymerization of [2-(acryloyloxy)ethyl]trimethylammonium chloride (AETMAC) and ethylene glycol diacrylate (EGDA) to form poly(AETMAC- co-EGDA), that not only helps to confine the soluble polysulfide species but also has the desired mechanical properties to allow stable cycling of high-sulfur loading cathodes. Through a combination of spectroscopic and electrochemical studies, we elucidate the chemical interactions that inhibit polysulfide shuttling. We also show that extensive cross-linkage enables this polymeric binder to exhibit a low degree of swelling as well as high tensile modulus and toughness. These attributes are essential to maintain the architectural integrity of the sulfur cathode during extended cycling. Using this material, Li-S cells with a high-sulfur loading (6.0 mg cm^-2) and a low-intermediate electrolyte/sulfur ratio (7 μL:1 mg) achieve an areal capacity of 5.4 mA h cm^-2 and can be (dis)charged for 300 cycles with stable reversible redox behavior after the initial cycles.

High aspect ratio sharp nanotip for nanocantilever integration at CMOS compatible temperature

In this paper, we demonstrate a novel low temperature nanofabrication approach that enables the formation of ultra-sharp high aspect ratio (HAR) and high density nanotip structures and their integration onto nanoscale cantilever beams. The nanotip structure consists of a nanoscale thermally evaporated Cr Spindt tip on top of an amorphous silicon rod. An apex radius of the tip, as small as 2.5 nm, has been achieved, and is significantly smaller than any other Spindt tips reported so far. 100 nm wide tips with aspect ratio of more than 50 and tip density of more than 5 × 10⁹ tips cm^-2 have been fabricated. The HAR tips have been integrated onto an array of 460 nm wide cantilever beams with high precision and yield. In comparison with other approaches, this approach allows the integration of HAR sharp nanotips with nano-mechanical structures in a parallel and CMOS compatible fashion for the first time to our knowledge. Potential applications include on-chip high-speed atomic force microscopy and field emission devices.

Micromechanical Origin of Particle Size Segregation

We computationally study the micromechanics of shear-induced size segregation and propose distinct migration mechanisms for individual large and small particles. While small particles percolate through voids without enduring contacts, large particles climb under shear through their crowded neighborhoods with anisotropic contact network. Particle rotation associated with shear is necessary for the upward migration of large particles. Segregation of large particles can be suppressed with inadequate friction, or with no rotation; increasing interparticle friction promotes the migration of large particles, but has little effect on the percolation of small particles.

Characterization of base roughness for granular chute flows

Base roughness plays an important role in the dynamics of granular flows but is still poorly understood due to the difficulty of its quantification. For a bumpy base made of spheres, at least two factors should be considered in order to characterize its geometric roughness, namely, the size ratio of flow to base particles and the packing arrangement of base particles. In this paper, we propose an alternative definition of base roughness, R_{a}, as a function of both the size ratio and the distribution of base particles. This definition is generalized for random and regular packings of multilayered spheres. The range of possible values of R_{a} is presented, and optimal arrangements for maximizing base roughness are studied. Our definition is applied to granular chute flows in both two- and three-dimensional configurations, and is shown to successfully predict whether slip occurs at the base. A transition is observed from slip to nonslip conditions as R_{a} increases. Critical values of R_{a} are identified for the construction of a nonslip base at various angles of inclination.

Clinical experience of trainee anaesthesiologists: logbook analysis

OBJECTIVE

To study the clinical experience acquired by trainee anaesthesiologists after 6 years of training in Hong Kong.

DESIGN

Retrospective observational study.

SETTING

Recognised anaesthesiology training posts in the Hong Kong Hospital Authority.

PARTICIPANTS

All anaesthesiology trainees who sat the Exit Assessment between January 2001 and June 2002 after completing more than 48 months of anaesthetic training.

MAIN OUTCOME MEASURES

Anaesthetic experience of trainees.

RESULTS

All data provided by 25 trainees were computed for analysis. Each trainee administered a mean of 2668 anaesthetics over a 6-year period, including 57 anaesthetics for thoracic surgery, 15 for cardiac surgery, 213 for caesarian section (34% under general anaesthesia), and 100 for neurosurgical operations. The paediatric anaesthesia exposure involved a mean of 12 neonates and 180 children who were younger than 4 years. Apart from cardiac and thoracic anaesthesia, there was no statistical difference in subspecialty anaesthetic experience among trainees from different parent hospitals.

CONCLUSION

The current training system provides sufficient anaesthetic experience in terms of case variety and subspecialty case numbers. There was uneven exposure to cardiac, thoracic, and paediatric anaesthesia. An accurate logbook that is reviewed regularly by a supervisor will help ensure adequate subspecialty exposure. An electronic logbook will facilitate a more comprehensive reviewing process.

Statistics of local temperature dissipation in high rayleigh number convection

We study the statistics of the local temperature dissipation in high Rayleigh number convection. We find that its probability distribution deviates from a lognormal, although very low order moments can be approximated by a lognormal distribution. Instead, the moments satisfy a hierarchy similar to that proposed by She and Leveque [Phys. Rev. Lett. 72, 336 (1994)] for the local energy dissipation. Moreover, the moments scale with the separation time. No change in the scaling behavior is observed when the Bolgiano scale is crossed, indicating that the statistics have the same nature in the buoyancy-driven and the inertia-driven regimes.

Securinine induced apoptosis in human leukemia HL-60 cells

AIM

To study whether securinine might induce apoptosis in human leukemia HL-60 cells.

METHODS

Inhibition of proliferation was measured using MTT assay. The amount of apoptotic cells was measured by flow cytometry. DNA fragmentation was visualized by DNA agarose gel electrophoresis and the cellular changes were observed by electron microscope.

RESULTS

Securinine 5-80 mg.L-1 elicited typical apoptosis morphological changes and DNA fragmentation in a concentration-dependent manner in HL-60 cells. Securinine inhibited HL-60 cell proliferation in a time- and concentration-dependent manner. The IC50 and 95% confidence limits were 27 (15-47) mg.L-1 after 12-h treatment with securinine.

CONCLUSION

Securinine induced apoptosis in HL-60 cells.

Elemene induces apoptosis and regulates expression of bcl-2 protein in human leukemia K562 cells

AIM

To study the antitumor action of elemene (Ele) and its mechanism.

METHODS

Inhibition of proliferation was measured with a colorimetric 3-[4,5-dimethyl thiazol-2-yl]-2,5-diphenyltetrazolium bromide (MTT) assay. Morphological assessment of apoptosis was performed with fluorescence microscope. DNA fragmentation was assessed by agarose gel electrophoresis and flow cytometry. The levels of bcl-2 protein was measured with flow cytometry.

RESULTS

Exposure of exponentially growing K562 cells to Ele 65-520 mumol. L-1 for 48 h resulted in growth arrest. The values of IC50 and 95% confidence limits were 220 (152-319) mumol.L-1. After treatment of K562 cells with Ele 130 mumol.L-1, marked morphological changes including "Apo bodies" reduction in volume were observed with fluorescence microscope. Agarose gel electrophoresis of DNA from cells treated with Ele for 48 h revealed "ladder" pattern. The levels of bcl-2 protein in K562 cells treated with Ele for 48 h were obviously decreased.

CONCLUSION

Ele induces apoptosis of K562 cells, which is related with the down-regulation of bcl-2 protein in K562 cells.

Atrophie blanche--a special form of vasculopathy

Although atrophie blanche is classified as a vasculitis, its presentation and management differ from the classical vasculitis. We present a patient with idiopathic atrophie blanche and discuss its management.

Retrospective study of the epidemiology of nodular vasculitis followed up in the National Skin Centre, Singapore

A seven-year retrospective study was done on histologically proven nodular vasculitis presenting at the National Skin Centre, Singapore. We collected 25 patients and found that they differed from the classical European model. They most commonly involved the shins and did not ulcerate. A tuberculous aetiology accounted for 28% of cases. Useful indicators of tuberculosis were a past history of tuberculosis, an abnormal chest X-ray and a strongly positive Mantoux test.