The capacity of soil as a carbon (C) sink is mediated by interactions between organic matter and mineral phases. However, previously proposed layered accumulation of organic matter within aggregate ...organo-mineral microstructures has not yet been confirmed by direct visualization at the necessary nanometer-scale spatial resolution. Here, we identify disordered micrometer-size organic phases rather than previously reported ordered gradients in C functional groups. Using cryo-electron microscopy with electron energy loss spectroscopy (EELS), we show organo-organic interfaces in contrast to exclusively organo-mineral interfaces. Single-digit nanometer-size layers of C forms were detected at the organo-organic interface, showing alkyl C and nitrogen (N) enrichment (by 4 and 7%, respectively). At the organo-mineral interface, 88% (72-92%) and 33% (16-53%) enrichment of N and oxidized C, respectively, indicate different stabilization processes than at organo-organic interfaces. However, N enrichment at both interface types points towards the importance of N-rich residues for greater C sequestration.
Surface functional groups constitute major electroactive components in pyrogenic carbon. However, the electrochemical properties of pyrogenic carbon matrices and the kinetic preference of functional ...groups or carbon matrices for electron transfer remain unknown. Here we show that environmentally relevant pyrogenic carbon with average H/C and O/C ratios of less than 0.35 and 0.09 can directly transfer electrons more than three times faster than the charging and discharging cycles of surface functional groups and have a 1.5 V potential range for biogeochemical reactions that invoke electron transfer processes. Surface functional groups contribute to the overall electron flux of pyrogenic carbon to a lesser extent with greater pyrolysis temperature due to lower charging and discharging capacities, although the charging and discharging kinetics remain unchanged. This study could spur the development of a new generation of biogeochemical electron flux models that focus on the bacteria-carbon-mineral conductive network.
Pyrogenic carbon contains redox-active functional groups and polyaromatic carbon matrices that are both capable of transferring electrons. Several techniques have been explored to characterize the ...individual electron transfer process of either functional groups or carbon matrices individually. However, simultaneous analysis of both processes remains challenging. Using an approach that employs a four-electrode configuration and dual-interface electron transfer detection, we distinguished the electron transfer by functional groups from the electron transfer by carbon matrices and simultaneously quantified their relative contribution to the total electron transfer to and from pyrogenic carbon. Results show that at low to intermediate pyrolysis temperatures (400–500 °C), redox cycling of functional groups is the major mechanism with a contribution of 100–78% to the total electron transfer; whereas at high temperatures (650–800 °C), direct electron transfer of carbon matrices dominates electron transfer with a contribution of 87–100%. Spectroscopic and diffraction analyses of pyrogenic carbon support the electrochemical measurements by showing a molecular-level structural transition from an enrichment in functional groups to an enrichment in nanosized graphene domains with increasing pyrolysis temperatures. The method described in this study provides a new analytical approach to separately quantify the relative importance of different electron transfer pathways in natural pyrogenic carbon and has potential applications for engineered carbon materials such as graphene oxides.
Interoception refers to a collection of processes by which the state of the body is transmitted back to the brain, giving rise to awareness of the internal milieu, and motivating behavioural ...responses to homeostatically regulate internal state. Recent work has begun to explore the relevance of this construct to drug addiction: drugs of abuse and drug-related stimuli induce pronounced peripheral changes, and damage to a brain region known to support interoception (the insula) disrupts nicotine dependence. This article critically reviews existing accounts of addiction that suggest impaired interoception contributes to drug abuse. Conceptually, we argue that existing addiction interoception models could be usefully extended by considering (i) the multiple components of the bodily feedback system (signal, perception, and appraisal) and (ii) how individual differences in these three components impact on cognitive-affective processing in addiction. Empirically, whilst no studies have examined direct behavioural measures of interoception in addicted populations, several indirect lines of experimental work that pertain to this altered interoception hypothesis are presented. Clinical implications are discussed.
Atomic vibrations control all thermally activated processes in materials, including diffusion, heat transport, phase transformations and surface chemistry. Recent developments in scanning ...transmission electron microscopy (STEM) have enabled nanoscale probing of vibrational modes using electron energy-loss spectroscopy (EELS)1,2. Although atomically resolved analysis is routine in STEM, vibrational spectroscopy employing oscillating dipoles yields signals originating from regions tens of nanometres in size, because the scattering angles are only a few microradians3. Recently, it has been shown that energy-filtered images recorded at high scattering angles display atomic resolution4. Here we show, using conventional on-axis EELS, that non-dipole, impact scattering vibrational signals are present, and exhibit atomic resolution. This on-axis signal shows variations in the spectral peak shape and intensity as the electron probe is scanned across an individual atomic column in a Si sample. Although atomic spatial resolution in coherent elastic scattering will complicate the quantitative interpretation of spectra from crystals, the change in peak shape provides compelling evidence that the vibrational EELS excitation process is highly localized. High spatial resolution is also demonstrated in SiO2, an amorphous polar material. Our approach represents an important technical advance that will provide new insights into the local thermal, elastic and kinetic properties of materials.
A series of experiments is presented that establishes for the first time the role of some of the key design parameters of porous carbons including surface area, pore volume, and pore size on battery ...performance. A series of hierarchical porous carbons is used as a model system with an open, 3D, interconnected porous framework and highly controlled porosity. Specifically, carbons with surface areas ranging from ≈500–2800 m2 g−1, pore volume from ≈0.6–5 cm3 g−1, and pore size from micropores (≈1 nm) to large mesopores (≈30 nm) are synthesized and tested. At high sulfur loadings (≈80 wt% S), pore volume is more important than surface area with respect to sulfur utilization. Mesopore size, in the range tested, does not affect the sulfur utilization. No relationship between porosity and long‐term cycle life is observed. All systems fail after 200–300 cycles, which is likely due to the consumption of the LiNO3 additive over cycling. Moreover, cryo‐scanning transmission electron microscopy imaging of these carbon–sulfur composites combined with X‐ray diffraction (XRD) provides further insights into the effect of initial sulfur distribution on sulfur utilization while also revealing the inadequacy of the indirect characterization techniques alone in reliably predicting distribution of sulfur within porous carbon matrices.
Porosity characteristics of porous carbons toward their performance as sulfur hosts in Li–S battery cathodes are systematically investigated at a high sulfur loading of ≈80 wt%. A series of hierarchical porous carbons with highly controlled porosity is employed as a model system. Additionally, cryo‐TEM is used for the first time to directly observe the sulfur distribution in the composite particles.
Two core features of depression are elevations in negative valence system (NVS) functioning and reductions in positive valence system (PVS) functioning. Existing psychological treatments have focused ...on the NVS and neglected the PVS, which may contribute to sub-optimal outcomes. The present mixed methods multiple randomised baseline case series preliminarily evaluates Augmented Depression Therapy (ADepT), a novel depression treatment targeting PVS and NVS disturbance, that aims both to reduce depression and enhance wellbeing. Eleven clinically depressed participants were recruited. Intensive time series analyses showed that 7/11 participants improved on both wellbeing and depression. Reliable and clinically significant improvement was observed for 9/11 participants on at least one of these outcomes (and also across a range of other PVS and NVS outcomes). Group level analyses showed significant pre to post change on all outcomes. Benchmarking analyses indicated these effect sizes were at least comparable (and for some PVS outcomes superior) to existing treatments. Gains were largely sustained over one-year follow-up. Qualitative interviews indicated ADepT was feasible and acceptable. These findings provide preliminary support for ADepT as a novel depression treatment. Further evaluation, directly comparing ADepT to existing treatments using randomised controlled trial designs, is now required.
•A case series evaluated Augmented Depression Therapy (ADepT).•ADepT targets disturbances in negative and positive valence systems.•ADepT was acceptable to treatment resistant depressed clients.•ADepT was effective at reducing depression and building wellbeing.•ADepT may be superior to existing treatments at reducing anhedonia.
Interoception can be broadly defined as the sense of signals originating within the body. As such, interoception is critical for our sense of embodiment, motivation, and well-being. And yet, despite ...its importance, interoception remains poorly understood within modern science. This paper reviews interdisciplinary perspectives on interoception, with the goal of presenting a unified perspective from diverse fields such as neuroscience, clinical practice, and contemplative studies. It is hoped that this integrative effort will advance our understanding of how interoception determines well-being, and identify the central challenges to such understanding. To this end, we introduce an expanded taxonomy of interoceptive processes, arguing that many of these processes can be understood through an emerging predictive coding model for mind-body integration. The model, which describes the tension between expected and felt body sensation, parallels contemplative theories, and implicates interoception in a variety of affective and psychosomatic disorders. We conclude that maladaptive construal of bodily sensations may lie at the heart of many contemporary maladies, and that contemplative practices may attenuate these interpretative biases, restoring a person's sense of presence and agency in the world.
The importance of developing a better understanding of positive emotion regulation in both healthy and clinical populations is now recognised. This special edition brings together leading figures in ...the positive emotion regulation field and has contributions characterizing positive phenomena, differentiating them from negative phenomena, and evaluating underlying psychological mechanisms that drive these phenomena. This commentary reviews these articles to highlight challenges and opportunities for this emerging field, including the need to better characterize positive phenomena, to be more explicit about how the links between negative and positive phenomena are conceptualised, to evaluate more robustly underlying mechanisms, to standardize measurement of positive constructs, and to ensure that these scientific findings lead to meaningful changes in real-world policy and practice.
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