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A density functional theory method was employed to investigate the mechanism of C-O bond activation of butanoic acid substrates bearing the 8-aminoquinoline (AQ) group catalyzed by Pd(OAc)2. The whole reaction consists of five fundamental steps: the chelation of substrate A1, the C-H activation step, the C-N coupling step, the protodepalladation step, and the release of the final product. The calculated results indicated that the protodepalladation step is the rate-determining step with a free energy barrier of 24.3 kcal/mol. This theoretical study pointed out that the energy barriers of C-H activation in the presence and absence of AQ are 11.3 and 26.6 kcal/mol, respectively. This is to say that the installation of the AQ directing group is critical to the regioselectivity of C-H activation and the β-O elimination steps, and this reason enables selective activation of the γ C-O bond. Furthermore, this chelating functionality facilitated the protodepalladation step because the energy barrier of the protodepalladation step was decreased with the coordination of the AQ directing group with a Pd center, and that was 39.3 kcal/mol in the absence of AQ. This also explains why no product formation was observed in the experiment upon changing the directing AQ group to a phenylamino group. Finally, other substrates bearing the phenol leaving group at the β- and δ-positions of carbonyl were investigated in order to expand the applicability of the AQ directing strategy. This work could provide new theoretical insights into the activation of strong alkyl C(sp3) covalent bonds via the AQ directing strategy.

A density functional theory (DFT) study has been performed to investigate the mechanism of ruthenium-catalyzed deoxygenative hydroboration of carboxylic acid. The reduction of the carbonyl motif is suggested to proceed via an intramolecular 1,3-hydride shift mechanism. The second HBpin coordination intermediate with the Ru center could facilitate the pinBOBpin reductive elimination and the PhCH2OBpin reductive elimination step. The energy span for the reaction is 25.2 kcal mol−1.

The particular work environment of transmission lines makes it liable to malfunction because of the foreign bodies attached to the power equipment. However, traditional detection methods are difficult to identify the exact category of foreign bodies and ignore the relationship between a foreign body and power equipment, which is correlated to determining whether there is a fault or not. In order to detect and distinguish the foreign bodies and give fault warnings automatically in transmission line patrol with high accuracy and efficiency, we improve the original YOLOv5 object detection model and propose a novel fusion detection model using multi-scale appearance and relationship features. The proposed model is capable of transmission line foreign body category detection and fault determination. By comparing with the original YOLOv5, the proposed model shows better accuracy and achieves the strong ability to give the fault determination simultaneously, which makes it convenient for power system operators and protects the safe and stable operation of the power system.

The palladium-catalyzed oxidative borylation reaction of

In order to ensure the driving safety of high-altitude highway tunnel and effectively reduce the lighting cost, this paper adopts the method considering the influence of automobile headlights luminance which combines reaction time incremental theory at different altitudes and lighting design simulation calculation. The paper has studied the design pattern of high-altitude highway tunnel, which are dominated by fixed lighting and supplemented by automotive lighting. The results show that: to ensure driving safety, the luminance of the lighting design for interior zone of highway tunnel increases with the increasing altitude. Based on the supplementary lighting of automobile headlights, the lighting design standards for the interior zone of high-altitude highway tunnel(the altitude is 2000m, 3000m, 4000m, 5000m respectively) are 0.73cd/m2, 0.82cd/m2, 0.91cd/m2, 1.0cd/m2.

The reaction mechanisms of the hydrogenation of [(η5-C5H2-1,2,4-Me3)2Hf]2(NCO) (μ2-N) (1) were studied using density functional theory (DFT) method. The calculated results indicate that the first step is the addition of H2 to the Hf N double bond, the second step is the insertion of isocyanate into the bridging metal hydride. The metal centers with a low electronegativity benefits the hydrogenation of 1. Then the reaction mechanisms of allenes with 1 were also investigated. The calculated results imply that the allenes with larger hindrance tend to undergo 1,2 addition with 1, the allenes with smaller hindrance tend to undergo 2+2 cycloaddition with 1, which is in good agreement with experimental results.

The palladium-catalyzed oxidative borylation reaction of N-tosylhydrazones has been developed. The reaction features mild conditions, broad substrate scope, and good functional group tolerance. It thus represents a highly efficient and practical method for the synthesis of di-, tri-, and tetrasubstituted alkenylboronates from readily available N-tosylhydrazones. One-pot Suzuki coupling and other transformations highlight the synthetic utility of the approach. DFT calculations have revealed that palladium-carbene formation and subsequent boryl migratory insertion are the key steps in the catalytic cycle. The high stereoselectivity observed in the formation of trisubstituted alkenylboronates has been explained by distortion-interaction analysis and NBO analysis.

According to the lighting energy-saving standards of plateau tunnels, the optimal lighting parameters in the middle segment of the highway tunnel is investigated under the conditions of plateau environment. With the minimum total power consumption as the target and the tunnel driving safety as the basic conditions, this article sets up parameter models of centerline layout, centerline sideways, symmetrical sides, and staggered sides in total 4 styles of distribution lights in tunnel interior zone. It is divided into different groups, each of which simulates 15 sets of parameters with different lamp spacing and compares the average luminance of different lamp forms and spacing conditions. The results show that: under the same spacing, the luminance of staggered sides arrangement is the highest, and the effect of centerline sideways is the worst. With the increase of the altitude, the safe lamp spacing decreases. The spacing of distribution lights in the middle section of the tunnel with the altitude of 2000m, 3000m, 4000m and 5000m is 47.5m, 42.5m, 37.5m and 35m respectively.

Lighting accounts for a large proportion of energy consumption in highway tunnels. In the context of the “low-carbon economy” and “energy conservation and emission reduction” strategies, this article starts from designing energy conservation, and discusses energy saving of light sources, lamp arrangement, control system, and auxiliary lighting. It summarizes the related research results, and puts forward some insights on the future energy saving design of highway tunnel lighting in China, and provides a reference for highway tunnel lighting design.

Shade avoidance syndrome enables shaded plants to grow and compete effectively against their neighbors. In Arabidopsis, the shade-induced de-phosphorylation of the transcription factor PIF7 (PHYTOCHROME-INTERACTING FACTOR 7) is the key event linking light perception to stem elongation. However, the mechanism through which phosphorylation regulates the activity of PIF7 is unclear. Here, we show that shade light induces the de-phosphorylation and nuclear accumulation of PIF7. Phosphorylation-resistant site mutations in PIF7 result in increased nuclear localization and shade-induced gene expression, and consequently augment hypocotyl elongation. PIF7 interacts with 14-3-3 proteins. Blocking the interaction between PIF7 and 14-3-3 proteins or reducing the expression of 14-3-3 proteins accelerates shade-induced nuclear localization and de-phosphorylation of PIF7, and enhances the shade phenotype. By contrast, the 14-3-3 overexpressing line displays an attenuated shade phenotype. These studies demonstrate a phosphorylation-dependent translocation of PIF7 when plants are in shade and a novel mechanism involving 14-3-3 proteins, mediated by the retention of PIF7 in the cytoplasm that suppresses the shade response.