Ideas and Perspectives: A Strategic Assessment of Methane and Nitrous Oxide Measurements In the Marine Environment

In the current era of rapid climate change, accurate characterization of climate-relevant gas dynamics-namely production, consumption, and net emissions-is required for all biomes, especially those ecosystems most susceptible to the impact of change. Marine environments include regions that act as net sources or sinks for numerous climateactive trace gases including methane (CH4) and nitrous oxide (N2O). The temporal and spatial distributions of CH4 and N2O are controlled by the interaction of complex biogeochemical and physical processes. To evaluate and quantify how these mechanisms affect marine CH4 and N2O cycling requires a combination of traditional scientific disciplines including oceanography, microbiology, and numerical modeling. Fundamental to these efforts is ensuring that the datasets produced by independent scientists are comparable and interoperable. Equally critical is transparent communication within the research community about the technical improvements required to increase our collective understanding of marine CH4 and N2O. A workshop sponsored by Ocean Carbon and Biogeochemistry (OCB) was organized to enhance dialogue and collaborations pertaining to marine CH4 and N2O. Here, we summarize the outcomes from the workshop to describe the challenges and opportunities for near-future CH4 and N2O research in the marine environment

Sequence building block for magnetic resonance spectroscopy on Siemens VE‐series scanners

Publication status: PublishedAbstractWe present a sequence building block (SBB) that embeds magnetic resonance spectroscopy (MRS) into another sequence on the Siemens VE platform without any custom hardware. This enables dynamic studies such as functional MRS (fMRS), dynamic shimming and frequency correction, and acquisition of navigator images for motion correction. The SBB supports nonlocalised spectroscopy (free induction decay), STimulated Echo Acquisition Mode single voxel spectroscopy, and 1D, 2D and 3D phase‐encoded chemical shift imaging. It can embed 1H or X‐nuclear MRS into a 1H sequence; and 1H‐MRS into an X‐nuclear sequence. We demonstrate integration into the vendor's gradient‐recalled echo sequence. We acquire test data in phantoms with three coils (31P/1H, 13C/1H and 2H/1H) and in two volunteers on a 7‐T Terra MRI scanner. Fifteen lines of code are required to insert the SBB into a sequence. Spectra and images are acquired successfully in all cases in phantoms, and in human abdomen and calf muscle. Phantom comparison of signal‐to‐noise ratio and linewidth showed that the SBB has negligible effects on image and spectral quality, except that it sometimes produces a nuclear Overhauser effect (NOE) signal enhancement for multinuclear applications in line with conventional 1H NOE pulses. Our new SBB embeds MRS into a host imaging or spectroscopy sequence in 15 lines of code. It allows homonuclear and heteronuclear interleaving. The package is available through the standard C2P procedure. We hope this will lower the barrier for entry to studies applying dynamic fMRS and for online motion correction and B0‐shim updating.</jats:p

Strategies for surface immobilization of whole bacteriophages: A review

International audienceBacteriophage immobilization is a key unit operation in emerging biotechnologies, enabling new possibilities for biodetection of pathogenic microbes at low concentration, production of materials with novel antimicrobial properties, and fundamental research on bacteriophages themselves. Wild type bacteriophages exhibit extreme binding specificity for a single species, and often for a particular subspecies, of bacteria. Since their specificity originates in epitope recognition by capsid proteins, which can be altered by chemical or genetic modification, their binding specificity may also be redirected toward arbitrary substrates and/or a variety of analytes in addition to bacteria. The immobilization of bacteriophages on planar and particulate substrates is thus an area of active and increasing scientific interest. This review assembles the knowledge gained so far in the immobilization of whole phage particles, summarizing the main chemistries, and presenting the current state-of-the-art both for an audience well-versed in bioconjugation methods as well as for those who are new to the field

The efficacy in vitro and in vivo of bacteriocin against Erwinia amylovora : comparison of biological and chemical control of fire blight

peer reviewe

Recycling of nitrogen and light noble gases in the Central American subduction zone: constraints from 15 N 15 N

International audienceHow much nitrogen and light noble gases are recycled in modern subduction zones is unclear. Fumaroles act as a means for passive degassing in arcs. They receive variable contributions of volatiles from arc magmas, themselves sourced from the mantle wedge. The gas compositions reflect the extent of volatile enrichment in sub-arc mantle sources and constrain slab dehydration. However, contributions from atmospheric components in fumaroles are unavoidable. For N2, neon and argon, the atmospheric components are challenging to discern from slab-derived components. Here, we report 15N15N measurements from eight fumaroles and seven bubbling springs, along the Central American arc. Our new 15N15N data are coupled with noble gases measurements and show that air-derived components in volcanic gas discharges can easily be underestimated, in both fumaroles and springs, using conventional stable isotope or noble gases methods. We show that, in the absence of 15N15N data, previously used tracers for air (e.g., δ26 15N N, N2/Ar, N2/He, among others) may lead to erroneous conclusions regarding the origin of volatiles in mixed gases. In contrast, 15N15N data provide quantitative constraints on the nature and contributions of both atmospheric and magmatic components. Most springs are heavily dominated by air-derived N2, while fumaroles show substantial contributions of volcanic endmembers. Based on the fumarole data, we show that magma sources beneath the central American arc are enriched in all volatiles relative to 3He, by two to three orders of magnitude compared to the MORB source. We use new 15N15N data to obtain source N2/3He, 3He/36Ar and 3He/22Ne ratios which we then use to compute volcanic N2, Ar and Ne degassing fluxes. Using this approach, we show that outgassing fluxes appear to match subduction fluxes in the Central America subduction zone. We determine an N2 outgassing flux of between 4.0 x 10^8 and 1.0 x10^9 mol N2/y, comparable to the subduction flux of 5.7 x 108 mol N2/yr determined previously. We obtain a similar conclusion for 22Ne and 38 36Ar. 39 Overall, the volatile fluxes in the central American subduction zone no longer seem to 40 require net transfer of N2, Ar, and Ne, to the deep mantl

3,4,6-Trimethyl-1-phenyl-5-(thiophen-3-yl)-1H-pyrazolo[3,4-b]pyridine

In the title compound, C19H17N3S, the pyrazolo[3,4-b]pyridine unit is slightly bowed across the C—C bond common to the two rings. In the crystal, ribbons extending along the a-axis direction are formed by C—H...π(ring) interactions. The ribbons are packed into corrugated layers inclined to the ac plane by approximately 22°. The thiophenyl group is rotationally disordered over two sites 180° apart in a 0.606 (2)/0.394 (2) ratio

Ethyl 4-(3,4,6-trimethyl-1-phenyl-1H-pyrazolo[3,4-b]pyridin-5-yl)benzoate

In the title compound, C24H23N3O2, the dihedral angles between the pyrazolopyridine ring system (r.m.s. deviation = 0.001 Å) and the N-bound and C-bound benzene rings are 15.95 (2) and 83.71 (4)°, respectively. The conformation of the former is influenced by an intramolecular C—H...N hydrogen bond, which generates an S(6) ring. In the crystal, stepped layers are generated by three sets of C—H...π interactions