Liquid organic hydrogen carriers (LOHCs) based on α,ω-alkanediol/lactone systems offer significantly lower dehydrogenation enthalpies than conventional aromatic carriers. This study investigates how the chain length and branching of alkyl substituents on the lactone ring influence the thermodynamic equilibrium of reversible hydrogen storage. Using a hybrid approach combining experimental thermochemistry and high-level quantum-chemical calculations (G3MP2), the reaction enthalpies, entropies, and Gibbs energies for both liquid and gas phases have been determined. Results reveal that extending the chain and increasing the branching of the alkyl group substantially reduce the Gibbs reaction energy. For instance, 2-tert-butyl-γ-butyrolactone exhibits a negative Gibbs reaction energy (−5.3 kJ·mol−1 at 298.15 K), indicating that thermodynamically spontaneous hydrogen release is possible at room temperature, provided suitable catalysts are available. However, while highly branched substituents greatly facilitate hydrogen release, they reduce volumetric hydrogen storage density and make the reverse hydrogenation step more challenging. Ultimately, a structure-property analysis demonstrates that tuning the size and branching of alkyl substituents provides a versatile strategy to balance the competing thermodynamic demands of hydrogen storage and release, enabling the rational design of tailored diol/lactone LOHCs.
To make a hydrogen economy feasible, it is crucial to identify efficient hydrogen storage technologies. While storing hydrogen by hydrogenation of aromatic and dehydrogenation of alicyclic hydrocarbons is technically feasible, it is associated with a high energy demand for hydrogen release that limits the energetic efficiency of the storage cycle if no suitable source of waste heat is available. This study investigates whether the release of hydrogen through the cyclization of diols forming lactones is energetically more favorable. To this end, equilibrium constants for the dehydrogenation reactions at 298.15 K, 400 K, and 500 K were determined using a combination of combustion calorimetry, vapor pressure measurements, and quantum chemical calculations. The results reveal that, compared to aromatic hydrocarbons, the equilibrium position for the dehydrogenation of diols is significantly more favorable for hydrogen release, and the reaction enthalpies are markedly lower. The most advantageous properties were observed for the 1,4-butanediol/gamma-butyrolactone system. The reaction enthalpy per mole of hydrogen for the dehydrogenation at 298.15 K is exceptionally low, at 42.5 kJ & sdot;mol-1. High hydrogen yields can already be expected at temperatures below 400 K at ambient pressure. Under such conditions, hydrogen release from 1,4-butanediol can be carried out with low energy input for heating the hydrogen carrier and for providing the enthalpy of reaction. This reduced thermal demand contributes to a higher prospective energy efficiency of the respective hydrogen storage cycle, which may represent in some application scenarios a significant economic advantage. Thermodynamics of reversible hydrogen storage with LOHC systems: 1,4-butanediol/gamma-butyrolactone, 1,5-pentanediol/delta-valerolactone and 1,6-hexanediol/s-caprolactone was studied in this work.
Recruitment in marine invertebrates with planktonic larvae, such as mussels Mytilus spp., is influenced by a complex interplay of environmental, ecological, and genetic factors. In the subarctic White Sea, recent climate-driven shifts in temperature and seasonality may affect spawning phenology, larval duration, and settlement patterns, ultimately impacting larval survival, post-settlement mortality, and genetic composition of populations. This study investigates the temporal patterns of Mytilus larval abundance and settlement on suspended substrates, with a focus on genetic variation among cohorts. We tested two hypotheses: (1) settlement occurs in multiple waves driven by genetically distinct larval cohorts, and (2) post-settlement selection shapes genetic structure of spat over time. Planktonic sampling revealed a single pronounced peak of veliger and pediveliger larvae, followed by a major spatfall in July. Contrary to expectations, no secondary peaks were observed, indicating a synchronized spawning event. Genetic analysis confirmed the presence of M. edulis, M. trossulus, and their hybrids among settlers. Post-settlement selection significantly altered species composition, with M. trossulus dominating at 0.5 m depth, while M. edulis prevailed at 2.5 m, likely due to selective predation by seastars Asterias rubens. These findings reveal the central role of post-settlement ecological filtering in shaping genetic diversity and species composition in mixed Mytilus populations in a subarctic White Sea. The study provides new insights into recruitment processes and population resilience of Mytilus spp. in rapidly changing high-latitude environments.
Abstract Land subsidence induced by underground coal mining consistently leads to persistent ponding in coal-grain overlapping areas (COAs), substantially impairing agricultural productivity. However, amid stringent farmland protection policies, mining operations face significant sustainability challenges. In this study, Guqiao Coal Mine in Anhui of China, is taken as a case, and four mining-reclamation schemes were conducted to compare patterns, and applicable conditions for each scheme are proposed based on concurrent mining and reclamation (CMR). Results show that: (1) Historically, traditional mining-reclamation (TMR) dominated due to low immediate reclamation costs despite extensive farmland loss; (2) Currently, earthwork-conserving CMR (ECMR) offers practical advantages by balancing economic investment and farmland reclamation. ECMR enhances land reclamation and reduces indirect costs, but leads to premature farmland degradation and prolonged compensation burdens; (3) Henceforth, reducing-degradation CMR (RCMR) can eliminate farmland degradation but is constrained by low coal-extraction rates, making it less feasible under current coal economic constraints; (4) In the prospective future, coupling CMR (CCMR) delays land degradation while improving reclamation efficiency, shortening the restoration cycle by 42% for ECMR, and raising coal-extraction rate to over 92% for RCMR. It restores 70% of degraded farmland and reduces seedling compensation costs by over 63 million yuan for ECMR in 30 years. CCMR also has strong performance in reducing surface ponding, maintaining grain security, and minimizing social displacement. Our findings underscore CCMR's superiority in aligning economic, ecological, and social objectives. It offers a replicable model for sustainable resource management in C1OAs globally, particularly under tightening environmental and agricultural policies.
The long-time, large-distance behaviour of a randomly walking particle on a random rough surface in a uniform gravitational field is studied by means of the field-theoretic renormalization group (RG). The random walk is governed by the Fokker–Planck equation for the particle’s probability distribution function, while the surface is described by the conserved Kardar–Parisi–Zhang (CKPZ) model due to Sun, Guo and Grant [Phys. Rev. A 40 6763 (1989)]. The corresponding field-theoretic model is logarithmic at d = 2 and is shown to be multiplicatively renormalizable. The standard RG analysis based on the minimal subtraction scheme (where the ultraviolet divergences have the form of the poles in ε =2-d ) reveals no infrared (IR) attractive fixed points. However, it shows that a certain IR irrelevant (in the sense of Wilson) term (composite operator) in the corresponding De Dominicis–Janssen action functional, necessarily omitted in that scheme, is in fact inevitably needed to exhaustively describe the IR behaviour of the relevant Green’s functions. Thus, we use a non-conventional formulation of the renormalization scheme in fixed d dimensions, in which that operator is included from the very beginning into the action functional and is treated on the equal footing with the other terms. That scheme reveals at least one nontrivial IR attractive fixed point, elusive in the standard RG approach. The resulting asymptotic scaling expressions appear rather cumbersome, as they simultaneously involve two different critical dimensions of time/frequency (so-called weak scaling) and describe several different asymptotic sub-domains of the whole IR asymptotic region.
