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With the development of salt cavern gas storage technology, the construction of large-scale salt cavern gas storage using sediment voids is expected to solve the problems of low effective volume formation rate and poor construction economy of high-impurity salt mines. At present, there are few studies on the long-term operational mechanical behavior of salt cavern gas storage under the influence of sediment accumulation. The present paper studies the influence of sediment height, particle gradation, and operating pressure on the stability of salt caverns by constructing a coupling model of sediment particle discontinuous medium and surrounding rock continuous medium. The continuous–discontinuous coupling algorithm is suitable for analyzing the influence of sediment height and particle gradation on the creep shrinkage of salt caverns. The increase in sediment height slows down the creep shrinkage of the cavern bottom, which strengthens the restraining effect on the surrounding rock of the cavern. As a result, the position of the maximum displacement of the surrounding rock moves to the upper part of the cavern. The sediment particle gradation has little effect on the cavern volume shrinkage rate. The greater the coarse particle content, the smaller the cavern volume shrinkage rate. The greater the operating pressure, the more conducive to maintaining the stability of the cavern. This situation slows down the upward movement of the sediment accumulation and increases the gas storage space in the upper part of the cavern. The obtained results can provide a reference for evaluating the long-term operational stability of sediment-type high-impurity salt cavern gas storage. [ABSTRACT FROM AUTHOR]

The rapid increase of aging population poses a great challenge on the public medical resources. Home health care (HHC), which provides the care services for the elderly and patients with mild disease, is an emerging approach to cope with such difficulty. This work formulates a stochastic HHC scheduling and routing problem with skill requirements to minimize total operation time. A stochastic programming model is given to mathematically define it. Then, a hybrid approach combining the genetic algorithm (GA) and simulation optimization with an approximated allocation (AA) rule is designed. The GA aims to search candidate solutions, while the simulation optimization method focuses on improving the efficiency of evaluating them. Numerical results show that the AA rule is more effective than equal allocation and proportional to variance rules in guiding the GA to find promising solutions. As a consequence, the designed approach acquires the better solutions for the problem under consideration. [ABSTRACT FROM AUTHOR]

Ene reductases (ERs) are attractive biocatalysts in terms of their high enantioselectivity and expanded substrate scope. Recent works have proved that synthetic nicotinamide coenzyme biomimetics (NCBs) can be used as easily accessible alternatives to natural cofactors in ER‐catalyzed reactions. However, the structure‐reactivity relationships between NCBs and ERs and influence factors are still poorly understood. In this study, a series of C‐5 methyl modified NCBs were synthesized and tested in the PETNR‐catalyzed asymmetric reductions. The physicochemical properties of these NCBs including electrochemical properties, stability, and kinetic behavior were studied in detail. The results showed that hydrophobic interaction caused by the introduced methyl group contributed to the stabilization of binding conformation in enzyme active site, resulting in comparable catalytic activity with that of NADPH. Molecular dynamics and steered molecular dynamics simulations were further performed to explain the binding mechanism between PETNR and NCBs, which revealed that stable catalytic conformation, appropriate donor‐acceptor distance and angle, as well as free dissociation energy are important factors affecting the activity of NCBs. [ABSTRACT FROM AUTHOR]

Transition metal-free electrochemical approaches for the N-cyanation of secondary amines and the α C-cyanation of tertiary amines have been well established, with products being obtained in moderate to good yields and with good functional group tolerance under ambient conditions. The synthetic application of the protocols has been highlighted through scale-up experiments in a galvanostatic mode. Preliminary mechanistic investigation has confirmed that TBAB played a critical role in N-cyanation transformation and has indicated that the transformation might proceed via a free radical process. [ABSTRACT FROM AUTHOR]