A fossil assigned to the extant ixodid genus Haemaphysalis was previously described from the Late Cretaceous (ca. 99 Ma) Burmese amber. Haemaphysalis (Alloceraea) cretacea was considered the oldest, and only, fossil representative of this genus. Significant criticism was raised regarding possible misidentification of this amber fossil. Microtomography of the original holotype and new material allows new perspectives on this controversy. A new fossil nymph is described and both fossils are considered Alloceraea cretacea comb. nov. nymphs based on a series of morphological characters: no genital aperture, eyeless, 11 festoons, coxa I simple with a short, wide triangular spur. Specific morphological features for the ‘structurally primitive’ Alloceraea are discussed and include palpi elongate, with long setae on palps, the hypostome dorsally longer than the chelicera and the corona visible distally and with a specific distribution of the denticles. Alloceraea and its sister genus Archaeocroton (that includes amber fossil taxa), share a common ancestor with Haemaphysalis sensu stricto, indicating a minimum divergence time of at least 100 MYA for these lineages. In addition, a fossil of Bothriocroton has also been described from Burmese amber. This genus with Cryptocroton groups basal to the Alloceraea/Archaecroton-Haemaphysalis assemblage forming a monophyletic clade named Haematobothrion. A synthesis of the fossil information and the current systematic understanding of the Haematobothrion allows new hypotheses about the origins of this group and the various lineages it comprises. Notably that the major Haematobothrion lineages originated and diverged during the time period when the Burma terrane was migrating from Australia to Asia.

Chirped coherent Rayleigh–Brillouin scattering (CRBS) is a flow diagnostic technique that offers high signal-to-noise ratios and nanosecond temporal resolution. To extract information of dilute gas flow, experimental spectra must be compared with theoretical predictions derived from the Boltzmann equation. In this work, we develop a MATLAB code that deterministically solves the Boltzmann equation (with a modelled collision kernel for the inverse power-law potential) to compute CRBS spectra, enabling each line shape to be obtained in approximately one minute. We find that the CRBS spectrum is highly sensitive to the intermolecular potential and that rapid chirping generates fine ripples around the Rayleigh peak along with spectral asymmetries.

A computational fluid dynamics simulation of subcooled flow boiling of water at 10.5 ${\rm bar}$, with an applied heat flux of $1\,{\rm MW}\,{\rm m}^{-2}$ and subcooling of 10 ${\rm K}$, was performed using an interface tracking method. The simulation replicated the conditions of an experiment conducted at MIT. The objectives are to elucidate heat-transfer mechanisms in moderate-pressure subcooled boiling and to validate the simulation method, with a focus on quantities that are difficult to measure experimentally, such as the distributions of velocity, temperature, bubble number density and heat-flux partitioning. Due to the small bubble size under high pressure, fine grids are required. Simulated bubble shapes, wall temperatures and vapour area fractions show good agreement with the experimental results. The simulations reveal that a very thin liquid layer (${\lt}4\,\unicode{x03BC}{\rm m}$) surrounding the bubbles is highly effective at removing heat from the surface. The local wall heat fluxes beneath medium and large bubbles, excluding the heat flux associated with seed-bubble generation, are approximately 0.9 and 0.4 ${\rm MW}\,{\rm m}^{-2}$, respectively; the latter is smaller because of the presence of thicker liquid films (14–70 $\unicode{x03BC}{\rm m}$) that thermally insulate the wall. In the single-phase liquid region, the heat transfer coefficient reaches $42\,{\rm kW}\,{\rm m}^{-2}\,{\rm K}^{-1}$ as a result of strong turbulent heat flux in the wall-normal direction; this turbulent heat flux is approximately eight times larger than in the equivalent single-phase liquid flow.

Thin liquid films play an instrumental role in the coating industry. In many cases, these films consist of multiple components and are applied in multiple layers. However, multilayer multicomponent coatings can readily develop thickness non-uniformities due to Marangoni flows driven by solute concentration gradients. Previous flow visualisation experiments have demonstrated that the addition of surfactant can suppress such non-uniformities, but the physical mechanisms underlying this suppression have not yet been definitively established. We investigate the growth of film-height non-uniformities in a two-layer multicomponent coating consisting of a solute-rich bottom layer, a solute-depleted top layer and surfactant. A lubrication-theory-based model that accounts for vertical and lateral gradients in solute and surfactant concentrations is developed. The resulting coupled nonlinear partial differential equations describing the film height, solute concentration and surfactant concentration are solved with a pseudospectral method. Our findings reveal that surfactant-induced Marangoni flows can significantly decrease film-height non-uniformities by competing with Marangoni flows due to solute concentration gradients. Several simplifications of the governing equations are explored to determine how well predictions from these simplified models compare with the full lubrication-theory-based model, thereby providing insight into dominant physical mechanisms in different parameter regimes. The role of surfactant solubility and sorption kinetics in controlling perturbation growth is also examined.

The Liolopidae Dollfus, 1934 is a small family of digenetic trematodes with sexual adults parasitic in aquatic reptiles and amphibians. Liolopids exploiting snakes are constrained to Harmotrema Nicoll, 1914, but the genus includes species with presumably freshwater life cycles parasitic in terrestrial snakes as well as species with presumably marine life cycles parasitic in viviparous sea snakes and amphibious kraits. We hypothesize that this ecological distinction implies substantial separation in evolutionary history and propose Sagaratrema De Silva, Pathirana & Martin n. g. to accommodate the liolopids in marine snakes. Three species are delineated through an integrated approach, from novel collections of viviparous sea snakes in Sri Lanka, Sagaratrema rajapaksei De Silva, Pathirana & Martin n. sp., Sagaratrema rajakarunae De Silva, Pathirana & Martin n. sp. and Sagaratrema indicum (Chattapadhyaya, 1970) n. comb. (= H. indica) originally reported from India. Three other species known from marine snakes are transferred from Harmotrema to the new genus: S. laticaudae (Yamaguti, 1933) n. comb. (designated as the type-species), S. eugari (Tubangui & Masilungan, 1936) n. comb. and S. linguiforme (Wang, 1987) n. comb. (= H. linguiforme). The 3 species from Sri Lanka are similarly genetically distinct in sympatry as each is relative to S. laticaudae from Japan. Following these proposals, Harmotrema is revised and rendered monotypic for the type-species H. infecundum. Morphologically, Sagaratrema is distinguished from Harmotrema and other liolopid genera by the arrangement of the excretory vesicles, distribution of the vitellarium and size and shape of the body.