EUREC⁴A

The science guiding the EUREC⁴A campaign and its measurements is presented. EUREC⁴A comprised roughly 5 weeks of measurements in the downstream winter trades of the North Atlantic – eastward and southeastward of Barbados. Through its ability to characterize processes operating across a wide range of scales, EUREC⁴A marked a turning point in our ability to observationally study factors influencing clouds in the trades, how they will respond to warming, and their link to other components of the earth system, such as upper-ocean processes or the life cycle of particulate matter. This characterization was made possible by thousands (2500) of sondes distributed to measure circulations on meso- (200 km) and larger (500 km) scales, roughly 400 h of flight time by four heavily instrumented research aircraft; four global-class research vessels; an advanced ground-based cloud observatory; scores of autonomous observing platforms operating in the upper ocean (nearly 10 000 profiles), lower atmosphere (continuous profiling), and along the air–sea interface; a network of water stable isotopologue measurements; targeted tasking of satellite remote sensing; and modeling with a new generation of weather and climate models. In addition to providing an outline of the novel measurements and their composition into a unified and coordinated campaign, the six distinct scientific facets that EUREC⁴A explored – from North Brazil Current rings to turbulence-induced clustering of cloud droplets and its influence on warm-rain formation – are presented along with an overview of EUREC⁴A's outreach activities, environmental impact, and guidelines for scientific practice. Track data for all platforms are standardized and accessible at https://doi.org/10.25326/165 (Stevens, 2021), and a film documenting the campaign is provided as a video supplement

EUREC⁴A

The science guiding the EUREC⁴A campaign and its measurements is presented. EUREC⁴A comprised roughly 5 weeks of measurements in the downstream winter trades of the North Atlantic – eastward and southeastward of Barbados. Through its ability to characterize processes operating across a wide range of scales, EUREC⁴A marked a turning point in our ability to observationally study factors influencing clouds in the trades, how they will respond to warming, and their link to other components of the earth system, such as upper-ocean processes or the life cycle of particulate matter. This characterization was made possible by thousands (2500) of sondes distributed to measure circulations on meso- (200 km) and larger (500 km) scales, roughly 400 h of flight time by four heavily instrumented research aircraft; four global-class research vessels; an advanced ground-based cloud observatory; scores of autonomous observing platforms operating in the upper ocean (nearly 10 000 profiles), lower atmosphere (continuous profiling), and along the air–sea interface; a network of water stable isotopologue measurements; targeted tasking of satellite remote sensing; and modeling with a new generation of weather and climate models. In addition to providing an outline of the novel measurements and their composition into a unified and coordinated campaign, the six distinct scientific facets that EUREC⁴A explored – from North Brazil Current rings to turbulence-induced clustering of cloud droplets and its influence on warm-rain formation – are presented along with an overview of EUREC⁴A's outreach activities, environmental impact, and guidelines for scientific practice. Track data for all platforms are standardized and accessible at https://doi.org/10.25326/165 (Stevens, 2021), and a film documenting the campaign is provided as a video supplement

Physiochemical cell surface and adhesive properties of Coryneform bacteria related to the presence and chain length of mycolic acids.

The presence and chain length of mycolic acids of bacteria of the genera Corynebacterium, Rhodococcus, Gordona, Mycobacterium, and Arthrobacter and of coryneform bacteria containing a type B peptidoglycan were related to the cell surface hydrophobicity of the bacteria, which in turn was related to adhesion of the cells to defined surfaces such as Teflon and glass. The origin of the overall negative charge of these bacteria is discussed

Chemical analysis of isolated cell walls of Gram-positive bacteria and the determination of the cell wall to cell mass ratio.

Cell walls of five Gram-positive bacterial strains, including four coryneforms and a Bacillus brevis strain were isolated and subsequently chemically analysed. The wall contribution to the total cell mass is calculated from a comparison of D-Lactate concentrations in hydrolysates of whole cells and isolated walls. D-Lactate concentrations are measured enzymatically after purification of the samples with active carbon. The optimum condition for the quantitative elimination of D-lactate from the peptidoglycan appears to be at 120°C and 4 M HCl. The wall fraction for the cells of the coryneform bacteria are in the range of 26-32% and is about 75% for the B. brevis cells. The peptidoglycan fraction in the walls of the coryneform bacteria was found to be rather high and constitutes about 23 to 31% of the cell wall dry weight. The protein content of the cell wall dry weight is somewhat lower and in the range of 7 to 14%. The peptidoglycan in the wall of the B. brevis strain forms a thin layer and contributes only about 5% to the cell wall dry weight. The high amount of proteins in the B. brevis cell wall (> 56%) can be attributed to a so called S(urface)layer

Chemical analysis of isolated cell walls of Gram-positive bacteria and the determination of the cell wall to cell mass ratio.

Cell walls of five Gram-positive bacterial strains, including four coryneforms and a Bacillus brevis strain were isolated and subsequently chemically analysed. The wall contribution to the total cell mass is calculated from a comparison of D-Lactate concentrations in hydrolysates of whole cells and isolated walls. D-Lactate concentrations are measured enzymatically after purification of the samples with active carbon. The optimum condition for the quantitative elimination of D-lactate from the peptidoglycan appears to be at 120°C and 4 M HCl. The wall fraction for the cells of the coryneform bacteria are in the range of 26-32% and is about 75% for the B. brevis cells. The peptidoglycan fraction in the walls of the coryneform bacteria was found to be rather high and constitutes about 23 to 31% of the cell wall dry weight. The protein content of the cell wall dry weight is somewhat lower and in the range of 7 to 14%. The peptidoglycan in the wall of the B. brevis strain forms a thin layer and contributes only about 5% to the cell wall dry weight. The high amount of proteins in the B. brevis cell wall (> 56%) can be attributed to a so called S(urface)layer