The incorporation of metal atoms into silicon nanowires during metal-particle-assisted growth is a critical issue for various nanowire-based applications. Here we have been able to access directly ...the incorporation and redistribution of metal atoms into silicon nanowires produced by two different processes at growth rates ranging from 3 to 40 nm s(-1), by using laser-assisted atom probe tomography and scanning transmission electron microscopy. We find that the concentration of metal impurities in crystalline silicon nanowires increases with the growth rate and can reach a level of two orders of magnitude higher than that in their equilibrium solubility. Moreover, we demonstrate that the impurities are first incorporated into nanowire volume and then segregate at defects such as the twin planes. A dimer-atom-insertion kinetic model is proposed to account for the impurity incorporation into nanowires.
The two-dimensional frequency-based omega-K method is known to be a suitable algorithm for Fully-Focused SAR (FF-SAR) radar altimeter processors, as its computational efficiency is much higher than ...equivalent time-based alternatives without much performance degradation. In this paper we provide a closed-form description of a two-dimensional frequency domain omega-K algorithm specific for instruments such as Poseidon-4 onboard Sentinel-6. The processor is validated with real data from point targets and over open ocean. Applications such as ocean swell retrieval and lead detection are demonstrated, showing the potentiality of the processor for future operational global-scale products.
A trihedral corner reflector has been used to evaluate the capability of passive reflectors to calibrate radar altimeters such as the Poseidon-4 altimeter on board Sentinel-6A. The reflector ...location, placed on the top of a mountain ridge and about 4-km off-nadir of the Sentinel-6A subsatellite track, allows capturing echoed signals with a Signal-to-Clutter Ratio around 40 dB when processing the received data with a Fully-Focussed SAR algorithm. Results obtained show a range bias of 33.9 mm with 8.5 mm of standard deviation and datation bias of -2.3 μs with standard deviation of 1.8 μs for the measurement campaign between September 2021 and April 2022. Such values are comparable to what is currently achieved by means of active transponders and therefore it is demonstrated that passive reflectors may be of interest to support radar altimeter regular calibration.
This work reports for the first time a highly efficient single‐crystal cesium tin triiodide (CsSnI3) perovskite nanowire solar cell. With a perfect lattice structure, low carrier trap density ...(≈5 × 1010 cm−3), long carrier lifetime (46.7 ns), and excellent carrier mobility (>600 cm2 V−1 s−1), single‐crystal CsSnI3 perovskite nanowires enable a very attractive feature for flexible perovskite photovoltaics to power active micro‐scale electronic devices. Using CsSnI3 single‐crystal nanowire in conjunction with highly conductive wide bandgap semiconductors as front‐surface‐field layers, an unprecedented efficiency of 11.7% under AM 1.5G illumination is achieved. This work demonstrates the feasibility of all‐inorganic tin‐based perovskite solar cells via crystallinity and device‐structure improvement for the high‐performance, and thus paves the way for the energy supply to flexible wearable devices in the future.
Efficient solar cell is achieved based on single‐crystal cesium tin triiodide nanowires with a long carrier lifetime and a large carrier mobility. The unique front‐surface‐field device structure of single‐crystal nanowire solar cells is proven to be an effective means of enhancing the carrier extraction and effectively boosting efficiency.
There is a growth of social concern regarding the deterioration of the environment. This has boosted the promotion of more efficient and sustainable mechanisms to deal with waste management. In ...Spain, waste management authorities and related organisations have engaged in a debate about the desirability to implement a packaging Deposit and Refund System (DRS). Under a DRS, consumers have to pay a “packaging deposit” as an added price to products purchased. This deposit is refunded when consumers return the used packaging to the point of sale in perfect conditions for identification. The implementation of such a system implies an important expense of resources. Its effectiveness in increasing the recycling rates crucially depends on public involvement and participation. This paper is grounded in previous studies on attitudes towards recycling. It presents the results of qualitative research performed to capture those factors that are determinant of the expected behaviour of citizens under the proposed DRS. The results indicate that the public perception of the DRS is very sensitive to the information provided. The description of some of the distinctive features of the new system, such as the mechanism associated with the economic deposit or the procedure to return packages, ultimately result in a rather negative evaluation and a reduced predisposition to participate in the waste collection. This study contributes to the analysis of what factors determine the adoption of the DRS, which is key to its success. It indicates that, beyond first impressions, the provision of information describing its features hinders the public's perception and has the potential to modify waste recycling behaviour.
•Information availability on waste management systems determines recycling behaviour.•Public engagement determines the effectiveness of waste collection systems.•Implementing a packaging Deposit and Refund System is under consideration in Spain.•Citizens have imperfect information on the implications of Deposit and Refund systems.•Informing about the traits of a Deposit and Refund System reduces expected adoption.
Abstract In the last decade we have witnessed a dramatic increase in the proportion and absolute number of bacterial pathogens resistant to multiple antibacterial agents. Multidrug-resistant bacteria ...are currently considered as an emergent global disease and a major public health problem. The B-Debate meeting brought together renowned experts representing the main stakeholders (i.e. policy makers, public health authorities, regulatory agencies, pharmaceutical companies and the scientific community at large) to review the global threat of antibiotic resistance and come up with a coordinated set of strategies to fight antimicrobial resistance in a multifaceted approach. We summarize the views of the B-Debate participants regarding the current situation of antimicrobial resistance in animals and the food chain, within the community and the healthcare setting as well as the role of the environment and the development of novel diagnostic and therapeutic strategies, providing expert recommendations to tackle the global threat of antimicrobial resistance.
•Silicon nanowires (NWs) grown on various substrates via Vapor–Liquid–Solid method.•Best crystallized SiNWs obtained using tin catalyst on silicon germanium substrate.•Morphology and crystalline ...nature strongly depend on the junction substrate-catalyst.•Substrate surface energy affects growth by regulating catalyst repartition.
The plasma-assisted Vapor-Liquid-Solid technique has been used to grow Silicon nanowires (SiNWs) on different substrates coated with 1 nm of tin and indium, to study the impact of the surface energy of the substrates on the morphology and structure of the NWs. The characteristics of the prepared Si NWs were analyzed by field emission scanning electron microscopy, X-ray diffraction (XRD) and Raman spectroscopy. The morphological characteristics differ in the density, diameter and length of the synthesized SiNWs. The mean diameters of these SiNWs range from 36 to 51 nm at the bottom and from 15 nm to 34 nm at the tip, while their average length varies from 0.2 μm up to 0.54 μm depending on the substrate and catalyst. The presence of strong peaks in all XRD patterns indicates that the as-grown SiNWs are highly crystalline. The XRD and Raman characteristics of the Sn and In catalyzed SiNWs formed on different substrates show that the crystalline grain size is influenced by the substrate nature and catalyst material, which can be related to the substrate surface energy. In particular shorter NWs with improved crystallinity (larger grain size) are obtained when using Sn as a catalyst on an amorphous silicon-germanium (a-SiGe) substrates, while the small grains were obtained on the same substrate when indium was used as a catalyst.
Both experimental and theoretical studies of fast and microscale physical phenomena occurring during the growth of vapour bubbles in nucleate pool boiling are reported. The focus is on the liquid ...film of micrometric thickness (a ‘microlayer’) that can form between the heater and the liquid–vapour interface of a bubble. The microlayer strongly affects the macroscale heat transfer and is thus important to be understood. The microlayer appears as a result of the inertial forces that cause the hemispherical bubble shape. It is shown that the microlayer can be seen as the Landau–Levich film deposited by the bubble foot edge during its receding. Paradoxically, the deposition is controlled by viscosity and surface tension. The microlayer profile measured with white-light interferometry, the temperature distribution over the heater, and the bubble shape are observed with synchronised high-speed cameras. According to the numerical simulations, the microlayer consists of two regions: a dewetting ridge near the contact line, and a longer and flatter bumped part. It is shown that the ridge cannot be measured by interferometry because of its intrinsic limitation on the interface slope. The ridge growth is linked to the contact line receding. The simulated dynamics of both the bumped part and the contact line agrees with the experiment. The physical origin of the bump in the flatter part of microlayer is explained.
To investigate the molecular epidemiology, antimicrobial susceptibility and carbapenem resistance determinants of Acinetobacter baumannii isolates from respiratory tract samples of patients diagnosed ...with ventilator-associated pneumonia (VAP) who were enrolled in the MagicBullet clinical trial.
A. baumannii isolates were prospectively cultured from respiratory tract samples from 65 patients from 15 hospitals in Greece, Italy and Spain. Susceptibility testing was performed by broth microdilution. Carbapenem resistance determinants were identified by PCR and sequencing. Molecular epidemiology was investigated using rep-PCR (DiversiLab) and international clones (IC) were identified using our in-house database.
Of 65 isolates, all but two isolates (97%) were resistant to imipenem and these were always associated with an acquired carbapenemase, OXA-23 (80%), OXA-40 (4.6%), OXA-58 (1.5%) or OXA-23/58 (1.5%). Resistance to colistin was 47.7%. Twenty-two isolates were XDR, and 20 isolates were pandrug-resistant (PDR). The majority of isolates clustered with IC2 (n = 54) with one major subtype comprising isolates from 12 hospitals in the three countries, which included 19 XDR and 16 PDR isolates.
Carbapenem resistance rates were very high in A. baumannii recovered from patients with VAP. Almost half of the isolates were colistin resistant, and 42 (64.6%) isolates were XDR or PDR. Rep-PCR confirmed IC2 is the predominant clonal lineage in Europe and suggests the presence of an epidemic XDR/PDR A. baumannii clone that has spread in Greece, Italy and Spain. These data highlight the difficulty in empirical treatment of patients with A. baumannii VAP in centres with a high prevalence of carbapenem-resistant A. baumannii.
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