Shapes and paths of an air bubble rising in quiescent liquids

Shapes and paths of an air bubble rising inside a liquid are investigatedexperimentally. About three hundred experiments are conducted in order togenerate a phase plot in the Galilei and Eotvos numbers plane, which separatesdistinct regimes in terms of bubble behaviour. A wide range of the Galilei andEotvos numbers are obtained by using aqueous glycerol solutions of differentconcentrations as the surrounding fluid, and by varying the bubble size. Thedynamics is investigated in terms of shapes, topological changes andtrajectories of the bubbles. Direct numerical simulations are conducted tostudy the bubble dynamics, which show excellent agreement with the experiments.To the best of our knowledge, this is the first time an experimentally obtainedphase plot showing the distinct behaviour of an air bubble rising in aquiescent medium is reported for such a large range of Galilei and Eotvosnumbers.

Temperature and field dependent magnetization studies on nano-crystalline ZnFe2O4 thin films

Altering thermal transport by strained-layer epitaxy

Since strain changes the interatomic spacing of matter and alters electron and phonon dispersion, an applied strain can modify the thermal conductivity k of a material. We show how the strain induced by heteroepitaxy is a passive mechanism to change k in a thin film. Molecular dynamics simulations of the deposition and epitaxial growth of ZnTe thin films provide insights into the role of interfacial strain in the conductivity of a deposited film. ZnTe films grow strain-free on lattice-matched ZnTe substrates, but similar thin films grown on a lattice-mismatched CdTe substrate exhibit ∼6% biaxial in-plane tensile strain and ∼7% uniaxial out-of-plane compressive strain. In the T = 700 K–1100 K temperature range, the conductivities of strained ZnTe layers decrease to ∼60% of their unstrained values. The resulting understanding of dk/dT shows that strain engineering can be used to alter the performance of a thermal rectifier and also provides a framework for enhancing thermoelectric devices.

Factors affecting the properties of highly conductive flexible ultrathin ITO films in confined large area magnetron sputtering in three dimensions

Large unidirectional spin Hall and Rashba-Edelstein magnetoresistance in topological insulator/magnetic insulator heterostructures

Thanks to its unique symmetry, the unidirectional spin Hall andRashba-Edelstein magnetoresistance (USRMR) is of great fundamental andpractical interest, particularly in the context of reading magnetization statesin two-terminal spin-orbit torque switching memory and logic devices. Recentstudies show that topological insulators could improve USRMR amplitude.However, the topological insulator device configurations studied so far in thiscontext, namely ferromagnetic metal/topological insulator bilayers andmagnetically doped topological insulators, suffer from current shunting by themetallic layer and low Curie temperature, respectively. Here, we report largeUSRMR in a new material category - magnetic insulator/topological insulatorbi-layered heterostructures. Such structures exhibit USRMR that is about anorder of magnitude larger than the highest values reported so far in all-metalTa/Co bilayers. We also demonstrate current-induced magnetization switchingaided by an Oersted field, and electrical read out by the USRMR, as a prototypememory device.

ATP compartmentation in plastids and cytosol of Arabidopsis thaliana revealed by fluorescent protein sensing

Matching ATP:NADPH provision and consumption in the chloroplast is a prerequisite for efficient photosynthesis. In terms of ATP:NADPH ratio, the amount of ATP generated from the linear electron flow does not meet the demand of the Calvin-Benson-Bassham (CBB) cycle. Several different mechanisms to increase ATP availability have evolved, including cyclic electron flow in higher plants and the direct import of mitochondrial-derived ATP in diatoms. By imaging a fluorescent ATP sensor protein expressed in living Arabidopsis thaliana seedlings, we found that MgATP 2- concentrations were lower in the stroma of mature chloroplasts than in the cytosol, and exogenous ATP was able to enter chloroplasts isolated from 4- and 5-day-old seedlings, but not chloroplasts isolated from 10- or 20-day-old photosynthetic tissues. This observation is in line with the previous finding that the expression of chloroplast nucleotide transporters (NTTs) in Arabidopsis mesophyll is limited to very young seedlings. Employing a combination of photosynthetic and respiratory inhibitors with compartment-specific imaging of ATP, we corroborate the dependency of stromal ATP production on mitochondrial dissipation of photosynthetic reductant. Our data suggest that, during illumination, the provision and consumption of ATP:NADPH in chloroplasts can be balanced by exporting excess reductants rather than importing ATP from the cytosol.

Fungal melanin stimulates surfactant protein D–mediated opsonization of and host immune response to Aspergillus fumigatus spores

Surfactant protein D (SP-D), a C-type lectin and pattern-recognition soluble factor, plays an important role in immune surveillance to detect and eliminate human pulmonary pathogens. SP-D has been shown to protect against infections with the most ubiquitous airborne fungal pathogen, Aspergillus fumigatus , but the fungal surface component(s) interacting with SP-D is unknown. Here, we show that SP-D binds to melanin pigment on the surface of A. fumigatus dormant spores (conidia). SP-D also exhibited an affinity to two cell-wall polysaccharides of A. fumigatus , galactomannan (GM) and galactosaminogalactan (GAG). The immunolabeling pattern of SP-D was punctate on the conidial surface and was uniform on germinating conidia, in accordance with the localization of melanin, GM, and GAG. We also found that the collagen-like domain of SP-D is involved in its interaction with melanin, whereas its carbohydrate-recognition domain recognized GM and GAG. Unlike un-opsonized conidia, SP-D-opsonized conidia were phagocytosed more efficiently and stimulated the secretion of proinflammatory cytokines by human monocyte-derived macrophages. Furthermore, SP-D -/- mice challenged intranasally with wildtype conidia or melanin ghosts ( i.e. hollow melanin spheres) displayed significantly reduced proinflammatory cytokines in the lung compared with wildtype mice. In summary, SP-D binds to melanin present on the dormant A. fumigatus conidial surface, facilitates conidial phagocytosis, and stimulates the host immune response.

Aspergillus fumigatus conidial metalloprotease Mep1p cleaves host complement proteins

Innate immunity in animals including humans encompasses the complement system, which is considered an important host defense mechanism against Aspergillus fumigatus , one of the most ubiquitous opportunistic human fungal pathogens. Previously, it has been shown that the alkaline protease Alp1p secreted from A. fumigatus mycelia degrades the complement components C3, C4, and C5. However, it remains unclear how the fungal spores ( i.e. conidia) defend themselves against the activities of the complement system immediately after inhalation into the lung. Here, we show that A. fumigatus conidia contain a metalloprotease Mep1p, which is released upon conidial contact with collagen and inactivates all three complement pathways. In particular, Mep1p efficiently inactivated the major complement components C3, C4, and C5 and their activation products (C3a, C4a, and C5a) as well as the pattern-recognition molecules MBL and ficolin-1, either by directly cleaving them or by cleaving them to a form that is further broken down by other proteases of the complement system. Moreover, incubation of Mep1p with human serum significantly inhibited the complement hemolytic activity and conidial opsonization by C3b and their subsequent phagocytosis by macrophages. Together, these results indicate that Mep1p associated with and released from A. fumigatus conidia likely facilitates early immune evasion by disarming the complement defense in the human host.

Effects of Bt-cotton on biological properties of Vertisols in central India

New national and regional bryophyte records, 54