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.

Clay swelling, an important phenomenon in natural systems, can dramatically affect the properties of soils and sediments. Of particular interest in low-salinity, saturated systems are osmotic hydrates, forms of smectite in which the layer separation greatly exceeds the thickness of a single smectite layer due to the intercalation of water. In situ X-ray diffraction (XRD) studies have shown a strong link between ionic strength and average interlayer spacing in osmotic hydrates but also indicate the presence of structural disorder that has not been fully described. In the present study the structural state of expanded smectite in sodium chloride solutions was investigated by combining very low electron dose, high-resolution cryogenic-transmission electron microscopy observations with XRD experiments. Wyoming smectite (SWy-2) was embedded in vitreous ice to evaluate clay structure in aqua. Lattice-fringe images showed that smectite equilibrated in aqueous, low-ionic-strength solutions, exists as individual smectite layers, osmotic hydrates composed of parallel layers, as well as disordered layer conformations. No evidence was found here for edge-to-sheet attractions, but significant variability in interlayer spacing was observed. Whether this variation could be explained by a dependence of the magnitude of long-range cohesive (van der Waals) forces on the number of layers in a smectite particle was investigated here. Calculations of the Hamaker constant for layer-layer interactions showed that van der Waals forces may span at least five layers plus the intervening water and confirmed that forces vary with layer number. Drying of the disordered osmotic hydrates induced re-aggregation of the smectite to form particles that exhibited coherent scattering domains. Clay disaggregation and restacking may be considered as an example of oriented attachment, with the unusual distinction that it may be cycled repeatedly by changing solution conditions.

In resource-limited countries, the lack of widespread screening masks the true situation of COVID-19. We conducted this study to assess SARS-CoV-2 spread by detection of specific antibodies and to determine associated factors. A population-based cross-sectional study was conducted. Subjects were tested for the presence of two antibodies (IgM and IgG) specific to SARS-CoV-2. Data collection was done using a smartphone with the KoboCollect application. Prevalence of antibodies was estimated with 95% confidence intervals. Logistic regression was used to determine factors associated with positive serological test. A total of 9,094 persons were tested in 4,340 households. The mean age was 30.18 ± 18.65 years, 46.5% male. The overall seroprevalence (prevalence, 95% CI) of SARS-CoV-2 antibodies was (48.2% [47.2%–49.2%]). Being vaccinated, having been in contact with a COVID-19 patient, being older than 50 years, living in a union, having secondary education and having tertiary education were factors independently associated with the likelihood of having anti-sars-CoV-2. We estimate in February 2022 that 48% persons had antibodies against the COVID-19 virus, more among those vaccinated. Vaccination intensification in low prevalence departments will reduce the risk of new outbreaks.

The site of L’anse de la République, Talmont-Saint-Hilaire, Vendée, France, belonging to the Beaker culture, was discovered by Roger Joussaume in the 1960s. It was subsequently investigated during the late 1980s and more recently in 2014. Several items excavated during these operations are clearly linked to metallurgy. This article assesses the results of new analyses (XRF, petrographic analysis, metallographic microscope observation, SEM and EDS microprobe analysis) undertaken on the different artefacts (copper residue, slags, smelting-crucible sherds), which allow the authors to assert that copper ore was smelted on the site. Radiocarbon dating of organic residue preserved on a ceramic sherd confirms the dating of the site to the earliest phase of the Beaker culture (2500 bc). The metallic copper produced here is characterised by two main impurities: arsenic and nickel. This provides an opportunity to review the extremely rare vestiges of Beaker metallurgy in France, which contrast with the numerous metal objects recovered. This article also considers the use of domestic smelting vessels for smelting ore; this technique may have been more widespread than previously thought in the Beaker culture on the Atlantic coast of Europe.

When a metal oxide surface is immersed in aqueous solution, it has the ability to bind, orient, and order interfacial water, affecting both chemical and physical interactions with the surface. Structured interfacial water thus possesses time-averaged, spatially varying polarization charge and potential that are comparable to those arising due to ion accumulation. It is well established that interfacial water structure propagates from the surface into bulk solution. Here, we show that interfacial water structure also propagates laterally, with important consequences. The constant pH molecular dynamics was used to impose a pH difference between opposite faces of a model goethite (α-FeOOH) nanoparticle and quantify water polarization charge on intervening faces. We find that the structure of water on one face is strongly affected by the structure on nearby surfaces, revealing the importance of long-range lateral hydrogen bonding networks with implications for particle aggregation, oriented attachment, and processes such as dissolution and growth.

The Ebola Virus Disease (EVD) outbreak in West Africa has been declared a public health emergency of international concern by the World Health Organization. The Ebola outbreak has led to the disruption of already fragile but essential health services and drug distribution systems; HIV clinical services in Liberia, Sierra Leone, and Guinea were particularly affected. Targeted approaches are necessary to protect the continuity of HIV treatment for people living with HIV and should be integrated within the broader Ebola response; this will save lives, prevent drug resistance, and decrease the likelihood of HIV transmission. (Disaster Med Public Health Preparedness. 2015;9:522–526)

Chromium-doped (0.5-10 % Cr:Ti molar ratio) nanocrystalline titania (5–6 nm) prepared via sol-gel method was examined by synchrotron-based wide angle x-ray scattering (WAXS) for crystal structure determination. Atomic pair-distribution functions (PDF) for both raw and heat-treated samples were obtained by Fourier transforms of the WAXS data. The PDF data were fitted using structural models of nanocrystalline titania that considered phase compositions, lattice parameters, atomic positions and thermal factors. The unit cell of Cr-doped nanocrystalline titania expanded 1-2 % with respect to bulk titania as a consequence of the substitution of Ti by Cr and the generation of oxygen vacancies. We observed a lattice contraction after heat-treatment that may be caused by the redistribution of Cr atoms to nanoparticle surfaces during phase transformation and particle coarsening.

The American people, especially in the eastern portion of the United States, are averse to political and social change particularly in institutions that have existed for a long period of time. A recent critic of American life has the following to say as a reason for this attitude of the American people:

“Among the many characteristics which foreign observers have ascribed to Americans are two about which there has been little difference of opinion. We are good-natured and we are individualists. Sermons have been preached against our good nature, so we need not dwell upon it. Much more important is our individualism—our absorption in individual interests and our reluctance to undertake things in combination with our neighbors or through the government. That individualism is an American characteristic is proved by a number of familiar facts. Thus the phrase ‘social reform,’ which in other countries suggests comprehensive plans of state action, is still usually associated in the United States with the welfare work of private corporations, private endowed schools of philanthropy…. Again, the coöperative movement which has made such signal progress in Europe, is in its infancy here.