Reading tea leaves worldwide: decoupled drivers of initial litter decomposition mass-loss rate and stabilisation

The breakdown of plant material fuels soil functioning and biodiversity. Currently, process understanding of global decomposition patterns and the drivers of such patterns are hampered by the lack of coherent large-scale datasets. We buried 36,000 individual litterbags (tea bags) worldwide and found an overall negative correlation between initial mass-loss rates and stabilization factors of plant-derived carbon, using the Tea Bag Index (TBI). The stabilization factor quantifies the degree to which easy-to-degrade components accumulate during early-stage decomposition (e.g. by environmental limitations). However, agriculture and an interaction between moisture and temperature led to a decoupling between initial mass-loss rates and stabilization, notably in colder locations. Using TBI improved mass-loss estimates of natural litter compared to models that ignored stabilization. Ignoring the transformation of dead plant material to more recalcitrant substances during early-stage decomposition, and the environmental control of this transformation, could overestimate carbon losses during early decomposition in carbon cycle models

GW190814: gravitational waves from the coalescence of a 23 solar mass black hole with a 2.6 solar mass compact object

We report the observation of a compact binary coalescence involving a 22.2–24.3 Me black hole and a compact object with a mass of 2.50–2.67 Me (all measurements quoted at the 90% credible level). The gravitational-wave signal, GW190814, was observed during LIGO’s and Virgo’s third observing run on 2019 August 14 at 21:10:39 UTC and has a signal-to-noise ratio of 25 in the three-detector network. The source was localized to 18.5 deg2 at a distance of - + 241 45 41 Mpc; no electromagnetic counterpart has been confirmed to date. The source has the most unequal mass ratio yet measured with gravitational waves, - + 0.112 0.009 0.008, and its secondary component is either the lightest black hole or the heaviest neutron star ever discovered in a double compact-object system. The dimensionless spin of the primary black hole is tightly constrained to �0.07. Tests of general relativity reveal no measurable deviations from the theory, and its prediction of higher-multipole emission is confirmed at high confidence. We estimate a merger rate density of 1–23 Gpc−3 yr−1 for the new class of binary coalescence sources that GW190814 represents. Astrophysical models predict that binaries with mass ratios similar to this event can form through several channels, but are unlikely to have formed in globular clusters. However, the combination of mass ratio, component masses, and the inferred merger rate for this event challenges all current models of the formation and mass distribution of compact-object binaries

Chemical vapor deposition of tin oxide: fundamentals and applications

Tin oxide thin layers have very beneficial properties such as a high transparency for visible light and electrical conductivity making these coatings suitable for a wide variety of applications, such as solar cells, and low-emissivity coatings for architectural glass windows. Each application requires different properties of the tin oxide layer. These properties can be tuned by adjusting the parameters of the chemical vapor deposition (CVD) process, the main technique used for applying the tin oxide layer to the substrate. This paper discusses the state of the art of the kinetic models for tin oxide CVD. In the case of organometallic precursors the gas-phase chemistry may be initiated by cleavage of the tin-carbon bond, followed by radical-driven chain reactions that enhance the overall decomposition rate. However, in commercial tin oxide CVD reactors the gas-phase temperature may be too low or the residence time too short for these reactions to occur, thereby favoring surface chemistry. Preliminary investigations of the MBTC-H2O-O 2 chemistry indicate that a mechanism comprising the reaction between gaseous oxygen and an adsorbed MBTC-H2O complex is a plausible model

Systematic study of p-shell nuclei via single-nucleon knockout reactions

Expérience au NSCLA systematic investigation of the inclusive cross sections for single-nucleon knockout reactions from p-shell nuclei has been performed. A total of seven reactions were studied for projectiles with masses between A = 7 and 10, having a wide range of nucleon separation energies. Results were obtained for a range of incident beam energies and targets. These differences were found to have a minimal impact on the deduced cross sections. Experimental results were compared to theoretical predictions based on variational Monte Carlo (VMC) nuclear structure calculations, whose radial overlap functions and neutron and proton densities were included in the reaction description. These results are compared with the conventional model, developed for heavier nuclei, that uses shell-model and Hartree-Fock structure inputs. The VMC-based calculations agreed with the experimental data for several reactions where deeply bound nucleons are removed but does not describe some of the more weakly bound nucleon removal cases with comparable accuracy