Variability in oxidative degradation of charcoal: influence of production variables and environmental exposure

<p>Charcoal is a key component of the Black Carbon (BC) continuum, where BC is characterized as a recalcitrant, fire-derived, polyaromatic material. Charcoal is an important source of palaeoenvironmental data, and of great interest as a potential carbon sink, due to its high apparent environmental stability. However, at least some forms of charcoal are clearly susceptible to environmental alteration and degradation over relatively short timescales. Although these processes have importance for the role of charcoal in global biogeochemistry, they remain poorly understood.</p> <p>Here we present results of an investigation into the susceptibility of a range of charcoal samples to oxidative degradation in acidified potassium dichromate. The study examines both freshly-produced charcoal, and charcoal exposed to environmental conditions for up to 50,000 years. We compare the proportion of carbon present in different forms between the samples, specifically with respect to the relative chemical resistance of these forms. This was undertaken in order to improve understanding of the post-depositional diagenetic changes affecting charcoal within environmental deposits.</p> <p>A wide range in chemical compositions are apparent both within and between the sample groups. In freshly-produced charcoal, material produced at 300 °C contains carbon with more labile forms than charcoal produced at ≥400 °C, signifying a key chemical change over the 300–400 °C temperature range. Charcoal exposed to environmental depositional conditions is frequently composed of a highly carboxylated aromatic structure and contains a range of carbon fractions of varying oxidative resistance. These findings suggest that a significant number of the environmental charcoals have undergone post-depositional diagenetic alteration. Further, the data highlight the potential for the use of controlled progressive oxidative degradation as a method to characterize chemical differences between individual charcoal samples.</p&gt

Polyphosphates as a source of enhanced P fluxes in marine sediments overlain by anoxic waters: Evidence from (31)P NMR

Sedimentary phosphorus (P) composition was investigated in Effingham Inlet, a fjord located on the west coast of Vancouver Island in Barkley Sound. Solid-state (31)P nuclear magnetic resonance (NMR) spectroscopy was applied to demineralized sediment samples from sites overlain by oxic and anoxic bottom waters. The two sites were similar in terms of key diagenetic parameters, including the mass accumulation rate, integrated sulfate reduction rate, and bulk sediment organic carbon content. In contrast, P benthic fluxes were much higher at the anoxic site. (31)P NMR results show that P esters and phosphonates are the major organic P species present at the surface and at depth in sediments at both sites. Polyphosphates were only found in the surface sediment of the site overlain by oxic waters. The varying stability of polyphosphates in microorganisms under different redox conditions may, in part, explain their distribution as well as differences in P flux between the two sites

Optimization of Non-Coding Regions for a Non-Modified mRNA COVID-19 Vaccine

The CVnCoV (CureVac) mRNA vaccine for SARS-CoV-2 has recently been evaluated in a phase 2b/3 efficacy trial in humans1. CV2CoV is a second-generation mRNA vaccine with non-modified nucleosides but optimized non-coding regions and enhanced antigen expression. Here we report a head-to-head study of the immunogenicity and protective efficacy of CVnCoV and CV2CoV in nonhuman primates. We immunized 18 cynomolgus macaques with two doses of 12 ug of lipid nanoparticle formulated CVnCoV, CV2CoV, or sham (N=6/group). CV2CoV induced substantially higher binding and neutralizing antibodies, memory B cell responses, and T cell responses as compared with CVnCoV. CV2CoV also induced more potent neutralizing antibody responses against SARS-CoV-2 variants, including the delta variant. Moreover, CV2CoV proved comparably immunogenic to the BNT162b2 (Pfizer) vaccine in macaques. While CVnCoV provided partial protection against SARS-CoV-2 challenge, CV2CoV afforded more robust protection with markedly lower viral loads in the upper and lower respiratory tract. Binding and neutralizing antibody titers correlated with protective efficacy. These data demonstrate that optimization of non-coding regions can greatly improve the immunogenicity and protective efficacy of a non-modified mRNA SARS-CoV-2 vaccine in nonhuman primates