Variation in carbon and nitrogen concentrations among peatland categories at the global scale

Publisher Copyright: © 2022 This is an open access article, free of all copyright, and may be freely reproduced, distributed, transmitted, modified, built upon, or otherwise used by anyone for any lawful purpose. The work is made available under the Creative Commons CC0 public domain dedication.Peatlands account for 15 to 30% of the world's soil carbon (C) stock and are important controls over global nitrogen (N) cycles. However, C and N concentrations are known to vary among peatlands contributing to the uncertainty of global C inventories, but there are few global studies that relate peatland classification to peat chemistry. We analyzed 436 peat cores sampled in 24 countries across six continents and measured C, N, and organic matter (OM) content at three depths down to 70 cm. Sites were distinguished between northern (387) and tropical (49) peatlands and assigned to one of six distinct broadly recognized peatland categories that vary primarily along a pH gradient. Peat C and N concentrations, OM content, and C:N ratios differed significantly among peatland categories, but few differences in chemistry with depth were found within each category. Across all peatlands C and N concentrations in the 10-20 cm layer, were 440 ± 85.1 g kg-1 and 13.9 ± 7.4 g kg-1, with an average C:N ratio of 30.1 ± 20.8. Among peatland categories, median C concentrations were highest in bogs, poor fens and tropical swamps (446-532 g kg-1) and lowest in intermediate and extremely rich fens (375-414 g kg-1). The C:OM ratio in peat was similar across most peatland categories, except in deeper samples from ombrotrophic tropical peat swamps that were higher than other peatlands categories. Peat N concentrations and C:N ratios varied approximately two-fold among peatland categories and N concentrations tended to be higher (and C:N lower) in intermediate fens compared with other peatland types. This study reports on a unique data set and demonstrates that differences in peat C and OM concentrations among broadly classified peatland categories are predictable, which can aid future studies that use land cover assessments to refine global peatland C and N stocks.Peer reviewe

Genetic association analysis identifies variants associated with disease progression in primary sclerosing cholangitis

Objective Primary sclerosing cholangitis (PSC) is a genetically complex, inflammatory bile duct disease of largely unknown aetiology often leading to liver transplantation or death. Little is known about the genetic contribution to the severity and progression of PSC. The aim of this study is to identify genetic variants associated with PSC disease progression and development of complications. Design We collected standardised PSC subphenotypes in a large cohort of 3402 patients with PSC. After quality control, we combined 130 422 single nucleotide polymorphisms of all patients-obtained using the Illumina immunochip-with their disease subphenotypes. Using logistic regression and Cox proportional hazards models, we identified genetic variants associated with binary and time-to-event PSC subphenotypes. Results We identified genetic variant rs853974 to be associated with liver transplant-free survival (p=6.07x10(-9)). Kaplan-Meier survival analysis showed a 50.9% (95% CI 41.5% to 59.5%) transplant-free survival for homozygous AA allele carriers of rs853974 compared with 72.8% (95% CI 69.6% to 75.7%) for GG carriers at 10 years after PSC diagnosis. For the candidate gene in the region, RSPO3, we demonstrated expression in key liver-resident effector cells, such as human and murine cholangiocytes and human hepatic stellate cells. Conclusion We present a large international PSC cohort, and report genetic loci associated with PSC disease progression. For liver transplant-free survival, we identified a genome-wide significant signal and demonstrated expression of the candidate gene RSPO3 in key liver-resident effector cells. This warrants further assessments of the role of this potential key PSC modifier gene.Peer reviewe

Modelling human choices: MADeM and decision‑making

Research supported by FAPESP 2015/50122-0 and DFG-GRTK 1740/2. RP and AR are also part of the Research, Innovation and Dissemination Center for Neuromathematics FAPESP grant (2013/07699-0). RP is supported by a FAPESP scholarship (2013/25667-8). ACR is partially supported by a CNPq fellowship (grant 306251/2014-0)

25th annual computational neuroscience meeting: CNS-2016

The same neuron may play different functional roles in the neural circuits to which it belongs. For example, neurons in the Tritonia pedal ganglia may participate in variable phases of the swim motor rhythms [1]. While such neuronal functional variability is likely to play a major role the delivery of the functionality of neural systems, it is difficult to study it in most nervous systems. We work on the pyloric rhythm network of the crustacean stomatogastric ganglion (STG) [2]. Typically network models of the STG treat neurons of the same functional type as a single model neuron (e.g. PD neurons), assuming the same conductance parameters for these neurons and implying their synchronous firing [3, 4]. However, simultaneous recording of PD neurons shows differences between the timings of spikes of these neurons. This may indicate functional variability of these neurons. Here we modelled separately the two PD neurons of the STG in a multi-neuron model of the pyloric network. Our neuron models comply with known correlations between conductance parameters of ionic currents. Our results reproduce the experimental finding of increasing spike time distance between spikes originating from the two model PD neurons during their synchronised burst phase. The PD neuron with the larger calcium conductance generates its spikes before the other PD neuron. Larger potassium conductance values in the follower neuron imply longer delays between spikes, see Fig. 17.Neuromodulators change the conductance parameters of neurons and maintain the ratios of these parameters [5]. Our results show that such changes may shift the individual contribution of two PD neurons to the PD-phase of the pyloric rhythm altering their functionality within this rhythm. Our work paves the way towards an accessible experimental and computational framework for the analysis of the mechanisms and impact of functional variability of neurons within the neural circuits to which they belong

Catalytic Dechlorination of Volatile Organic Carbons under Redox Conditions

Chlorinated hydrocarbons, such as perchloroethylene (PCE) and trichloroethylene (TCE), are persistent environmental hazards, due to improper disposal, affecting groundwater sources located near a variety of industrial processes. As many chlorinated hydrocarbons are suspected carcinogens, there is great interest in developing inexpensive and environmentally sound technologies for the remediation of contaminated sites. Current efforts focus on the use of soil-vapor extraction (SVE) to pass gas phase contaminants through a granular activated carbon bed (GAC), which creates solid toxic waste, and possibly more harmful by-products during GAC regeneration. This research focuses on the use of hydrogen and short-chain alkanes, in combination with oxygen, to promote the conversion of PCE over a Pt/Rh three-way catalyst. The use of both of a hydrocarbon and oxygen creates mixed reducing-oxidizing (redox) conditions. Results indicate that redox conditions result in the complete removal of the target compound and produces primarily CO₂, H₂O and HCl. The process has proven to be most effective near stoichiometric conditions with respect to the reducing and oxidizing agents (2:1 for H₂:O₂ and 1:5 for propane:O₂). Residence times in the reactor are typically on the order of 0.1 to 0.5 seconds and catalyst surface temperatures range from 200 °C to 550 °C, with PCE conversion greater than 99% starting at 450 °C under slightly reducing (H₂:O₂ > 2) conditions. Laboratory results suggest that the catalytic mechanism is a multiple step surface reaction involving the three reactants (H₂/C₃H₈, O₂ and PCE). A mechanism based on Langmuir- Hinshelwood kinetics has been developed in an attempt to model the process. The role of the cerium oxide present in a three-way catalyst on the direct oxidation of perchloroethylene (PCE) has also been explored. Experiments have shown that in the absence of an external oxidizing agent, PCE can be converted over an alumina supported Pt/Rh catalyst. This work hypothesizes that the chlorine atoms in the adsorbed PCE interact with oxygen in oxidized cerium, CeO₂, reducing the cerium and replacing the oxygen atoms to create CeCl₃. This process begins at a catalyst surface temperature of 300 °C and reaches 100% conversion at 400 °C

Catalytic dechlorination of volatile organic carbons under redox conditions

Chlorinated hydrocarbons, such as perchloroethylene (PCE) and trichloroethylene (TCE), are persistent environmental hazards, due to improper disposal, affecting groundwater sources located near a variety of industrial processes. As many chlorinated hydrocarbons are suspected carcinogens, there is great interest in developing inexpensive and environmentally sound technologies for the remediation of contaminated sites. Current efforts focus on the use of soil-vapor extraction (SVE) to pass gas phase contaminants through a granular activated carbon bed (GAC), which creates solid toxic waste, and possibly more harmful by-products during GAC regeneration. This research focuses on the use of hydrogen and short-chain alkanes, in combination with oxygen, to promote the conversion of PCE over a Pt/Rh three-way catalyst. The use of both of a hydrocarbon and oxygen creates mixed reducing-oxidizing (redox) conditions. Results indicate that redox conditions result in the complete removal of the target compound and produces primarily CO2, H2O and HCl. The process has proven to be most effective near stoichiometric conditions with respect to the reducing and oxidizing agents (2:1 for H2:O2 and 1:5 for propane:O2). Residence times in the reactor are typically on the order of 0.1 to 0.5 seconds and catalyst surface temperatures range from 200 °C to 550 °C, with PCE conversion greater than 99% starting at 450 °C under slightly reducing (H2:O2 > 2) conditions. Laboratory results suggest that the catalytic mechanism is a multiple step surface reaction involving the three reactants (H2/C3H 8, O2 and PCE). A mechanism based on Langmuir-Hinshelwood kinetics has been developed in an attempt to model the process. The role of the cerium oxide present in a three-way catalyst on the direct oxidation of perchloroethylene (PCE) has also been explored. Experiments have shown that in the absence of an external oxidizing agent, PCE can be converted over an alumina supported Pt/Rh catalyst. This work hypothesizes that the chlorine atoms in the adsorbed PCE interact with oxygen in oxidized cerium, CeO2, reducing the cerium and replacing the oxygen atoms to create CeCl3. This process begins at a catalyst surface temperature of 300 °C and reaches 100% conversion at 400 °C

Selection of Shale Preparation Protocol and Outgas Procedures for Applications in Low-Pressure Analysis

The low-pressure gas adsorption (LPGA) method for estimation of pore capacities, pore size distributions, and total surface area using adsorption–desorption isotherms is selected as an effective technique in pore characterization. A recent application of this method is to understand the complex and heterogeneous nature of shales across the globe. The LPGA experiments were conducted on shale samples from Barnett and Eagle Ford formations in the United States using CO₂ for micropores of 0.3–1.5 nm in diameter and N₂ and Ar as the adsorbates to focus on micropores from 1.5 to 2.0 nm and the lower range of mesopores above 2.0–27 nm in diameter. It was hypothesized that a significant error in estimations could occur due to inconsistencies in the shale outgas temperatures. It was observed that lower pore capacities result from lower outgas temperatures, and higher pore capacities result from increasing outgas temperatures. It is hypothesized that lower outgas temperatures fail to completely eliminate adsorbed moisture and adsorbed low-molecular weight hydrocarbon species from shale pores, which leaves the pores partially filled and as such result in lower values of pore capacity. By increasing the outgassing temperature, the adsorbed species in the pores are completely removed, yielding higher pore capacities. The cutoff temperature of 250 °C during outgassing for regeneration of “clean” shale pores was arrived at by analyzing the LPGA results of samples without any outgassing and samples outgassed at 60, 110, and 250 °C. The 250 °C maximum outgas temperature is intended to maximize the results of LPGA while minimizing structural changes to shales. Mass stabilization as shown by thermogravimetric analysis and magnetic suspension balance measurements support the assertion that the shale is not fundamentally altered by processes such as kerogen cracking until a temperature higher than 250 °C is reached. The kerogen had approximately 3.0% weight loss at 110 °C, with an additional 1.3% loss between 110 and 250 °C. Likewise, the desorption experiments carried out on clay at 110 °C were approximately 1.3%, with an additional 0.5% loss between 110 and 250 °C. On the basis of the interpretation of pore size distributions using the LPGA method, it was concluded that accurate shale characterization is achieved when the analysis is limited to results from relative pressures (<i>P</i>/<i>P</i>_o) less than or equal to 0.90. At higher relative pressures, the sizes of the adsorbate-occupied pores cannot be distinguished

Lhx1 Controls Terminal Differentiation and Circadian Function of the Suprachiasmatic Nucleus

Vertebrate circadian rhythms are organized by the hypothalamic suprachiasmatic nucleus (SCN). Despite its physiological importance, SCN development is poorly understood. Here, we show that Lim homeodomain transcription factor 1 (Lhx1) is essential for terminal differentiation and function of the SCN. Deletion of Lhx1 in the developing SCN results in loss of SCN-enriched neuropeptides involved in synchronization and coupling to downstream oscillators, among other aspects of circadian function. Intact, albeit damped, clock gene expression rhythms persist in Lhx1-deficient SCN; however, circadian activity rhythms are highly disorganized and susceptible to surprising changes in period, phase, and consolidation following neuropeptide infusion. Our results identify a factor required for SCN terminal differentiation. In addition, our in vivo study of combinatorial SCN neuropeptide disruption uncovered synergies among SCN-enriched neuropeptides in regulating normal circadian function. These animals provide a platform for studying the central oscillator’s role in physiology and cognition