Degradation kinetics of biochar from pyrolysis and hydrothermal carbonization in temperate soils

Background and Aims

Estimates of biochar residence times in soils range over three orders of magnitude. We present the first direct comparison between the biodegradation of a char from hydrothermal carbonization (htcBC) and pyrolysis (pyrBC) with high temporal resolution.

Methods

Mineralization of the biochars and their shared Miscanthus feedstock in three soils was determined directly by the ¹³CO₂ efflux using a novel method incorporating wavelength scanned cavity ring-down spectroscopy. Biochar half-life (t_1/2) was estimated with three empirical models.

Results

(1) The htcBC was readily biodegradable, whereas pyrBC was more recalcitrant. (2) Cumulative degradation of both biochars increased with soil organic carbon and nitrogen content. (3) The corrected Akaike information criterion (AIC_C) showed an overall preference for the double exponential model (DEM) reflecting a labile and a recalcitrant C-pool, over the first-order degradation model (FODM) and a logarithmic model. (4) The DEM resulted in t_1/2 ranging from 19.7–44.5, 0.7–2.1 and 0.8–1.3 years for pyrBC, htcBC and feedstock, respectively.

Conclusion

The degradation was rather similar between feedstock and htcBC but one order of magnitude slower for pyrBC. The AIC_C preferred FODM in two cases, where the DEM parameters indicated no distinction between a labile and recalcitrant carbon pool.     

Biaxial mechanical properties of the inferior vena cava in C57BL/6 and CB-17 SCID/bg mice

Multiple murine models have proven useful in studying the natural history of neovessel development in the tissue engineering of vascular grafts. Nevertheless, to better understand longitudinal changes in the biomechanics of such neovessels, we must first quantify native tissue structure and properties. In this paper, we present the first biaxial mechanical data for, and nonlinear constitutive modeling of, &QJ;the inferior vena cava from two models used in tissue engineering: wild-type C57BL/6 and immunodeficient CB-17 SCID/bg mice. Results show that inferior vena cava from the latter are significantly stiffer in the circumferential direction, both materially (as assessed by a stored energy function) and structurally (as assessed by the compliance), despite a lower intramural content of fibrillar collagen and similar wall thickness. Quantifying the natural history of neovessel development in different hosts could lead to increased insight into the mechanisms by which cells fashion and maintain extracellular matrix in order to match best the host stiffness while ensuring sufficient vascular integrity.     

Gastrointestinal absorption and metabolism of apple polyphenols ex vivo by the pig intestinal mucosa in the Ussing chamber

Polyphenols contained in food have various positive effects on human health. The absorption and metabolism of polyphenols in the intestinal tract needs to be studied to estimate these effects. The Ussing chamber technique was used to investigate the transport behavior of apple polyphenols through pig small intestinal mucosa, which served as a model for human gastrointestinal mucosa. The identities and concentrations of polyphenols and their metabolites in the half-chambers (luminal and basolateral) within an incubation period of 4 h were determined by HPLC–MS/MS and HPLC–DAD (DAD = diode-array detection). Flux values were also measured. It was found that 5-caffeoylquinic acid and caffeic acid were absorbed and translocated to the basolateral side (1.9 and 3.7%, respectively), but other compounds, including glycosides of phloretin and quercetin, were observed without translocation. A Ussing chamber utilizing pig small intestinal mucosa is a suitable model for assessing the effect of apple polyphenols on mucosal integrity and nutrition absorption across porcine mucosa.     

Fluorinated Cannabidiol Derivatives: Enhancement of Activity in Mice Models Predictive of Anxiolytic,Antidepressant and Antipsychotic Effects

Cannabidiol (CBD) is a major Cannabis sativa constituent, which does not cause the typical marijuana psychoactivity. However, it has been shown to be active in a numerous pharmacological assays, including mice tests for anxiety, obsessive-compulsive disorder, depression and schizophrenia. In human trials the doses of CBD needed to achieve effects in anxiety and schizophrenia are high. We report now the synthesis of 3 fluorinated CBD derivatives, one of which, 4''-F-CBD (HUF-101) (1), is considerably more potent than CBD in behavioral assays in mice predictive of anxiolytic, antidepressant, antipsychotic and anti-compulsive activity. Similar to CBD, the anti-compulsive effects of HUF-101 depend on cannabinoid receptors.     

Good‐bye to tropical alpine plant giants under warmer climates? Loss of range and genetic diversity in Lobelia rhynchopetalum

The main aim of this paper is to address consequences of climate warming on loss of habitat and genetic diversity in the enigmatic tropical alpine giant rosette plants using the Ethiopian endemic Lobelia rhynchopetalum as a model. We modeled the habitat suitability of L. rhynchopetalum and assessed how its range is affected under two climate models and four emission scenarios. We used three statistical algorithms calibrated to represent two different complexity levels of the response. We analyzed genetic diversity using amplified fragment length polymorphisms and assessed the impact of the projected range loss. Under all model and scenario combinations and consistent across algorithms and complexity levels, this afro‐alpine flagship species faces massive range reduction. Only 3.4% of its habitat seems to remain suitable on average by 2,080, resulting in loss of 82% (CI 75%–87%) of its genetic diversity. The remaining suitable habitat is projected to be fragmented among and reduced to four mountain peaks, further deteriorating the probability of long‐term sustainability of viable populations. Because of the similar morphological and physiological traits developed through convergent evolution by tropical alpine giant rosette plants in response to diurnal freeze‐thaw cycles, they most likely respond to climate change in a similar way as our study species. We conclude that specialized high‐alpine giant rosette plants, such as L. rhynchopetalum, are likely to face very high risk of extinction following climate warming.