Explore the vast range of titles available.

Episodes of chronic stress can result in psychic disorders like post-traumatic stress disorder, but also promote the development of metabolic syndrome and type 2 diabetes. We hypothesize that muscle, as main regulator of whole-body energy expenditure, is a central target of acute and adaptive molecular effects of stress in this context. Here, we investigate the immediate effect of a stress period on energy metabolism in Musculus gastrocnemius in our established C57BL/6 chronic variable stress (Cvs) mouse model. Cvs decreased lean body mass despite increased energy intake, reduced circadian energy expenditure (EE), and substrate utilization. Cvs altered the proteome of metabolic components but not of the oxidative phosphorylation system (OXPHOS), or other mitochondrial structural components. Functionally, Cvs impaired the electron transport chain (ETC) capacity of complex I and complex II, and reduces respiratory capacity of the ETC from complex I to ATP synthase. Complex I-OXPHOS correlated to diurnal EE and complex II-maximal uncoupled respiration correlated to diurnal and reduced nocturnal EE. Bioenergetics assessment revealed higher optimal thermodynamic efficiencies (ƞ-opt) of mitochondria via complex II after Cvs. Interestingly, transcriptome and methylome were unaffected by Cvs, thus excluding major contributions to supposed metabolic adaptation processes. In summary, the preclinical Cvs model shows that metabolic pressure by Cvs is initially compensated by adaptation of mitochondria function associated with high thermodynamic efficiency and decreased EE to manage the energy balance. This counter-regulation of mitochondrial complex II may be the driving force to longitudinal metabolic changes of muscle physiological adaptation as the basis of stress memory.

Water scarcity is a particularly severe challenge in arid and desert climates. While a substantial amount of water is present in the form of vapour in the atmosphere, harvesting this water by state-of-the-art dewing technology can be extremely energy intensive and impractical, particularly when the relative humidity (RH) is low (i.e., below ~40% RH). In contrast, atmospheric water generators that utilise sorbents enable capture of vapour at low RH conditions and can be driven by the abundant source of solar-thermal energy with higher efficiency. Here, we demonstrate an air-cooled sorbent-based atmospheric water harvesting device using the metal−organic framework (MOF)-801 [Zr 6 O 4 (OH) 4 (fumarate) 6 ] operating in an exceptionally arid climate (10–40% RH) and sub-zero dew points (Tempe, Arizona, USA) with a  thermal efficiency (solar input to water conversion) of ~14%. We predict that this device delivered over 0.25 L of water per kg of MOF for a single daily cycle. Harvesting water from the atmosphere is an important solution to water scarcity, but doing so in arid climates is highly challenging. Here, the authors develop a metal-organic framework-based water harvesting device that can deliver over 0.25 L of water per kg of adsorbent over a single cycle at relative humidities of 10–40% and at subzero dew points.

Cyclical heat engines are a paradigm of classical thermodynamics, but are impractical for miniaturization because they rely on moving parts. A more recent concept is particle-exchange (PE) heat engines, which uses energy filtering to control a thermally driven particle flow between two heat reservoirs1,2. As they do not require moving parts and can be realized in solid-state materials, they are suitable for low-power applications and miniaturization. It was predicted that PE engines could reach the same thermodynamically ideal efficiency limits as those accessible to cyclical engines3–6, but this prediction has not been verified experimentally. Here, we demonstrate a PE heat engine based on a quantum dot (QD) embedded into a semiconductor nanowire. We directly measure the engine’s steady-state electric power output and combine it with the calculated electronic heat flow to determine the electronic efficiency η. We find that at the maximum power conditions, η is in agreement with the Curzon–Ahlborn efficiency6–9 and that the overall maximum η is in excess of 70% of the Carnot efficiency while maintaining a finite power output. Our results demonstrate that thermoelectric power conversion can, in principle, be achieved close to the thermodynamic limits, with direct relevance for future hot-carrier photovoltaics10, on-chip coolers or energy harvesters for quantum technologies.

By electronically wiring-up living cells with abiotic conductive surfaces, bioelectrochemical systems (BES) harvest energy and synthesize electric-/solar-chemicals with unmatched thermodynamic efficiency. However, the establishment of an efficient electronic interface between living cells and abiotic surfaces is hindered due to the requirement of extremely close contact and high interfacial area, which is quite challenging for cell and material engineering. Herein, we propose a new concept of a single cell electron collector, which is in-situ built with an interconnected intact conductive layer on and cross the individual cell membrane. The single cell electron collector forms intimate contact with the cellular electron transfer machinery and maximizes the interfacial area, achieving record-high interfacial electron transfer efficiency and BES performance. Thus, this single cell electron collector provides a superior tool to wire living cells with abiotic surfaces at the single-cell level and adds new dimensions for abiotic/biotic interface engineering. Efficient management of electron transfer between living cells and solid abiotic surfaces is quite challenging. Here, the authors report the assembling of single cell electron collector for individual cell to promote the biotic/abiotic interfacial electron transfer at the single-cell level.

We calculate analytically the stochastic thermodynamic properties of an isothermal Brownian engine driven by a duo of time-periodic forces, including its Onsager coefficients, the stochastic work of each force, and the corresponding stochastic entropy production. We verify the relations between different operational regimes, maximum power, maximum efficiency, and minimum dissipation, and reproduce the signature features of the stochastic efficiency. All of these results are experimentally tested without adjustable parameters on a colloidal system.

New electrochemical ammonia (NH 3 ) synthesis technologies are of interest as a complementary route to the Haber–Bosch process for distributed fertilizer generation, and towards exploiting ammonia as a zero-carbon fuel produced via renewably sourced electricity 1 . Apropos of these goals is a surge of fundamental research targeting heterogeneous materials as electrocatalysts for the nitrogen reduction reaction (N 2 RR) 2 . These systems generally suffer from poor stability and NH 3 selectivity; the hydrogen evolution reaction (HER) outcompetes N 2 RR 3 . Molecular catalyst systems can be exquisitely tuned and offer an alternative strategy 4 , but progress has been thwarted by the same selectivity issue; HER dominates. Here we describe a tandem catalysis strategy that offers a solution to this puzzle. A molecular complex that can mediate an N 2 reduction cycle is partnered with a co-catalyst that interfaces the electrode and an acid to mediate proton-coupled electron transfer steps, facilitating N−H bond formation at a favourable applied potential (−1.2 V versus Fc +/0 ) and overall thermodynamic efficiency. Certain intermediates of the N 2 RR cycle would be otherwise unreactive via uncoupled electron transfer or proton transfer steps. Structurally diverse complexes of several metals (W, Mo, Os, Fe) also mediate N 2 RR electrocatalysis at the same potential in the presence of the mediator, pointing to the generality of this tandem approach. Using a molecular catalyst and a proton–electron transfer mediator in tandem delivers efficient electroreduction of nitrogen to ammonia at modest potentials, an approach that could be used to improve other important reactions.

Solid-state refrigeration offers potential advantages over traditional cooling systems, but few devices offer high specific cooling power with a high coefficient of performance (COP) and the ability to be applied directly to surfaces. We developed a cooling device with a high intrinsic thermodynamic efficiency using a flexible electrocaloric (EC) polymer film and an electrostatic actuation mechanism. Reversible electrostatic forces reduce parasitic power consumption and allow efficient heat transfer through good thermal contacts with the heat source or heat sink. The EC device produced a specific cooling power of 2.8 watts per gram and a COP of 13. The new cooling device is more efficient and compact than existing surface-conformable solid-state cooling technologies, opening a path to using the technology for a variety of practical applications.

Pilot-diesel-ignition ammonia combustion engines have attracted widespread attentions from the maritime sector, but there are still bottleneck problems such as high unburned NH 3 and N 2 O emissions as well as low thermal efficiency that need to be solved before further applications. In this study, a concept termed as in-cylinder reforming gas recirculation is initiated to simultaneously improve the thermal efficiency and reduce the unburned NH 3 , NO x , N 2 O and greenhouse gas emissions of pilot-diesel-ignition ammonia combustion engine. For this concept, one cylinder of the multi-cylinder engine operates rich of stoichiometric and the excess ammonia in the cylinder is partially decomposed into hydrogen, then the exhaust of this dedicated reforming cylinder is recirculated into the other cylinders and therefore the advantages of hydrogen-enriched combustion and exhaust gas recirculation can be combined. The results show that at 3% diesel energetic ratio and 1000 rpm, the engine can increase the indicated thermal efficiency by 15.8% and reduce the unburned NH 3 by 89.3%, N 2 O by 91.2% compared to the base/traditional ammonia engine without the proposed method. At the same time, it is able to reduce carbon footprint by 97.0% and greenhouse gases by 94.0% compared to the traditional pure diesel mode. Pilot-diesel-ignition ammonia combustion engines effective adoption is still limited by high unburned emissions and low thermal efficiency. Here, authors propose an in-cylinder reforming gas recirculation concept to improve engine thermal efficiency while reducing unburned NH3, NOx, N2O and GHG emissions.

In many real-world situations, there are constraints on the ways in which a physical system can be manipulated. We investigate the entropy production (EP) and extractable work involved in bringing a system from some initial distributionpto some final distributionp′, given that the set of master equations available to the driving protocol obeys some constraints. We first derive general bounds on EP and extractable work, as well as a decomposition of the nonequilibrium free energy into an “accessible free energy” (which can be extracted as work, given a set of constraints) and an “inaccessible free energy” (which must be dissipated as EP). In a similar vein, we consider the thermodynamics of information in the presence of constraints and decompose the information acquired in a measurement into “accessible” and “inaccessible” components. This decomposition allows us to consider the thermodynamic efficiency of different measurements of the same system, given a set of constraints. We use our framework to analyze protocols subject to symmetry, modularity, and coarse-grained constraints and consider various examples including the Szilard box, the 2D Ising model, and a multiparticle flashing ratchet.

In the overall life cycle energy consumption of China’s construction sector, building energy usage constitutes a significant portion, and the process of China’s dual carbon goals can be greatly accelerated by reducing building operation energy consumption. Solar energy, as a kind of renewable energy, is increasingly mature in construction applications. PV/T comprehensive utilization technology has attracted much attention in using solar energy. The flexible PV/T system can fit on the facade of various bending angles. This paper conducts indoor variable working conditions (irradiance and volume flow) and flexible PV/T and flexible PV contrast experiments on the existing flexible PV/T system. Observations reveal a direct correlation between irradiance, volume flow rate, electric power enhancement, and thermal efficiency in the flexible PV/T system. Flexible PV/T systems can produce more electricity than flexible PV systems at the same irradiance.