Search

ABSTRACT Reduction of carboxamides is an efficient approach to obtain the corresponding amines, albeit it is one of the most problematic. In this work, by use of pinacolborane (HBpin) as a reductant, the rare‐earth metal tris (arylamido) complex supported by a ferrocenyl‐modified arylamido ligand La[NH‐2,6‐iPr2‐4‐FcC6H2]3 was employed as a precatalyst for primary and secondary amide reductions. This catalyst system exhibited high activity toward hydroborative reduction of amides to amines under mild conditions, as well good tolerance for heteroatoms and functional groups in the reduction. A lanthanide hydride was experimentally verified as the active species and the reduction mechanism was proposed. [ABSTRACT FROM AUTHOR]

Interface engineering is widely used to enhance the efficiency and stability of photodetectors (PDs). Although fluorine-containing materials are ideal for interface modification, they are seldom used at the NiOx/perovskite interface. This paper reports on the use of Tris(pentafluorophenyl)borane (BCF) and 2,3,5,6-tetrafluoro-7,7,8,8- tetracyanoquinodimethane (F4-TCNQ)-modified NiOx HTL to achieve high-efficiency and high-stability PDs. This study shows that BCF and F4-TCNQ interact to provide better doping ability, form Lewis adducts with Pb2+, and enhance the crystallinity of their perovskites. Interaction with nickel oxide optimizes the Ni3+/Ni2+ ratio, thus improving conductivity and charge transport capability. The F4-TCNQ:BCF modification effectively reduces interface defects, improves carrier mobility, and enhances both the performance and stability of PDs in ambient air. The detector achieves a maximum EQE value of 89.4%, a dark current density of 1.51 × 10−10A cm−2, a detectivity of 6.33 × 1013 Jones, and a LDR of 133.4 dB. Additionally, the interfacially modified device maintains over 90% of its initial performance after one month of storage in ambient air. Our results highlight the importance of F4-TCNQ:BCF interface modification and provide a reference for the further research and development of perovskite devices. [ABSTRACT FROM AUTHOR]

Amomum villosum Lour. (A. villosum) is the original plant of the medicinal and culinary spice Amomi Fructus (Sharen) and is an important economic crop in the Lingnan region of China. During the cultivation and production of A. villosum, prolonged reliance on single asexual reproduction has exacerbated the degradation of its varieties, leading to inconsistent yields and quality. Building upon earlier cultivar selection efforts, this study provides a comprehensive evaluation of two newly bred A. villosum varieties (A11 and A12) from perspectives including plant traits, product characteristics, active ingredients, and multi-omics analysis. It was found that A12 plants display enhanced robustness, more aromatic fruits, higher yields, and elevated levels of bornyl acetate, A11 shows the advantage of a high camphor content, and the different metabolites and differentially expressed genes of the two varieties were significantly enriched in multiple metabolic pathways. Additionally, A12 contained more terpenoids and substances with aromatic odors such as sweet, fruity, floral, and green. Furthermore, a key gene (Wv_032842) regulating the acetylation of bornyl was discovered, and its significantly higher expression, in A12. In conclusion, this study has a guiding significance for the evaluation of germplasm resources and the breeding of excellent varieties of A. villosum. [ABSTRACT FROM AUTHOR]

Axle-box bearings are directly affected by wheel–rail impacts as fixedly connected to wheelset. As an inevitable wheel-failure, wheel flat can cause severe wheel-rail impact, which may deteriorate the performance of axle-box bearings, even threatening train running safety. To investigate the dynamic response of axle-box bearings excited by wheel flat, two rigid-flexible coupled vehicle dynamics models of motor and trailer cars are developed. The axle-box bearing, flexible axle-box and wheelset are thoroughly established in trailer car model. The gear transmission system and flexible gearbox are further integrated into motor car model relative to trailer model. The accuracies of models are verified by the field-test results. The dynamic responses of axle-box bearings excited by wheel flat are analyzed. Results indicate that the vibration and dynamic forces acting on axle-box bearing augment with the increasing of flat length. The vibrations intensify gradually from wheelset, inner ring, and outer ring to axle-box, particularly increasing significantly with long flat lengths. Moreover, the dynamic forces within axle-box bearing first increase before decreasing with the growing operating speed. Being structurally difference, wheel flat exerts more significant effects on the axial and radial forces within the bearings of motor car than those of trailer car. [ABSTRACT FROM AUTHOR]

Connections give diversified firms an advantage. This study investigates whether firms will be less diversified when the connections to the government are abruptly interrupted, using a dataset on the firm's subsidiaries and the political connectedness of all listed private firms in China. In 2013, an unanticipated reform intended to combat corruption forced all politically connected independent directors of listed firms to resign. We find that those affected firms become less diversified after the reform. The estimation results are not driven by changes in the number of subsidiaries, government development goals, CEO's political incentives, or other commercial system reforms. Placebo events for SOEs and firms' academic background yield no effects. The effects are larger for local connections and stronger institutions. We also find that depoliticized firms are less likely to enter regulated and profitable industries and acquire less government economic support. Our results suggest that diversified firms could be 'parasites' of the economic-political institutions in emerging markets. [ABSTRACT FROM AUTHOR]

Redox‐switchable catalysis is an efficient process to modulate the activity and/or selectivity in the polymerization with greater polymerization control and precision. In this work, the ferrocenyl‐functionalized diarylamines 4‐Fc‐C6H4NHC6H5 (HL1), 4‐Fc‐C6H4NH(2,6‐Me2C6H3) (HL2), and 2,6‐iPr2–4‐Fc‐C6H2NHC6H5 (HL3) were prepared and used as pro‐ligands to obtain the arylamido‐ligated rare‐earth metal complexes. Treatment of RE (CH2C6H4NMe2‐o)3 with 1 equiv. of HL1–3 in toluene afforded the ferrocenyl‐functionalized‐arylamido rare‐earth metal bis(o‐dimethylaminobenzyl) complexes L1Sc(CH2C6H4NMe2‐o)2 (1), L2RE(CH2C6H4NMe2‐o)2 (RE = Sc (2), Y (3)), and L3Y(CH2C6H4NMe2‐o)2 (4) in good yields. The compositions of these complexes were verified by NMR spectroscopy and elemental analysis. HL1 and HL3 were subjected to single‐crystal X‐ray diffraction. Electrochemical and NMR studies indicated that 4 could be oxidized with AgBF4 to generate the corresponding oxidized species 4ox, which could be facilely reduced back to 4 by use of CoCp2 as the reductant. The redox‐reversible ability between 4 and 4ox gave the chance to modulate the reactivity by switching the oxidized and reduced forms of one complex. For a controlled polymerization of ε‐caprolactone, 4 was active, and the polymerization process could be easily "on/off" switched by the redox reaction occurred on the ferrocenyl moiety. [ABSTRACT FROM AUTHOR]

Background: Gynostemma pentaphyllum (Thunb.) Makino, a well-known edible and medicinal plant, has anti-aging properties and is used to treataging-associated conditions such as diabetes, metabolic syndrome, and cardiovascular diseases. Gypenosides (GYPs) are the primary constituents of G. pentaphyllum. Increasing evidence indicates that GYPs are effective at preserving mitochondrial homeostasis and preventing heart failure (HF). This study aimed to uncover the cardioprotective mechanisms of GYPs related to mitochondrial regulation. Methods: The bioactive components in GYPs and the potential targets in treating HF were obtained and screened using the network pharmacology approach, followed by drug-disease target prediction and enrichment analyses. The pharmacological effects of GYPs in cardioprotection, mitochondrial function, mitochondrial quality control, and underlying mechanisms were further investigated in Doxorubicin (Dox)-stimulated H9c2 cardiomyocytes. Results: A total of 88 bioactive compounds of GYPs and their respective 71 drug-disease targets were identified. The hub targets covered MAPK, EGFR, PI3KCA, and Mcl-1. Enrichment analysis revealed that the pathways primarily contained PI3K/Akt, MAPK, and FoxO signalings, as well as calcium regulation, protein phosphorylation, apoptosis, and mitophagy process. In Dox-stimulated H9c2 rat cardiomyocytes, pretreatment with GYPs increased cell viability, enhanced cellular ATP content, restored basal oxygen consumption rate (OCR), and improved mitochondrial membrane potential (MMP). Furthermore, GYPs improved PINK1/parkin-mediated mitophagy without influencing mitochondrial fission/fusion proteins and the autophagic LC3 levels. Mechanistically, the phosphorylation of PI3K, Akt, GSK-3β, and the protein level of Mcl-1 was upregulated by GYP treatment. Conclusion: Our findings reveal that GYPs exert cardioprotective effects by rescuing the defective mitophagy, and PI3K/Akt/GSK-3β/Mcl-1 signaling is potentially involved in this process. [ABSTRACT FROM AUTHOR]

In order to solve the problem of underwater in-situ measurement of fuel assembly bending and twisting deformation, an underwater in-situ deformation measurement method of fuel assembly based on line laser 3D vision is proposed. The calibration of single-layer refraction-based underwater camera and plane-constrained optical plane calibration algorithms are used to solve the calibration problem of single measurement unit; ten groups of measurement units based on three-dimensional calibration tooling are quickly calibrated in situ to solve the problem of global coordinate unification of the measurement system and the bending and torsion accuracy of the calibration tooling is measured by laser tracking instrument or the comparative experimental verification of the measurement accuracy. The study shows that the developed underwater n-situ deformation measurement system for fuel assemblies based on line laser 3D vision has an error limit of 0.15° for twist measurement and 0.3 mm for bending measurement, and the whole measurement time is about 1 s, which is better than that of the existing measurement system in terms of the measurement efficiency and measurement error limit. [ABSTRACT FROM AUTHOR]

Resources–environment–economy coordinated development (REECD) is important for global sustainable development goals (SDGs). Integrated assessment model (IAM) is widely applied to investigate REECD‐related issues and design policy or technology development pathways. Accordingly, this study reviews existing literatures on the REECD related IAMs in terms of nexus mechanism, classification, theoretical basis and applicability, and puts forward possible expansion dimensions for improving the models. IAMs could be categorized into top‐down ones mainly based on computable general equilibrium and optimization theories, and bottom‐up ones generally based on engineering‐technological and ecology‐environmental analysis. Top‐down and bottom‐up combined IAMs are increasingly employed to evaluate the impacts of policy implementation, technological penetration and behavior modification, in order to improve the accuracy for decision‐making. Meanwhile, IAMs for REECD are need to be further developed to increase its applicability for analyzing high‐resolution and high‐frequency inventories of resource development and pollutant emissions. Existing IAMs should also embrace key resources consumption such as heavy and strategic metals. Due to tighter carbon emission space under 1.5‐degree and carbon‐neutral climate targets, the nexus mechanism of REECD would change significantly in future, which we need to characterize these variations in the models. Furthermore, researchers and developers should pay more attention to model improvement towards the developing and emerging economies. This article is categorized under:Sustainable Development > Emerging EconomiesSustainable Development > GoalsHuman and Social Dimensions > Energy and Climate Justice [ABSTRACT FROM AUTHOR]

In order to solve the problem of detecting and finding microcracks on concrete structures, a method on aerial detection of concrete microcracks based on fluorescence selective excitation was proposed in this study. Concentration brightness relationship curves for fluorescent solutions were plotted based on experimental analysis results. Specialised fluorescent aqueous solutions for concrete microcrack detection were identified as excitation reagents by integrating with the fluorescence development patterns of each solution. Concrete specimens containing authentic microcracks were prepared, and fluorescence selective excitation detection tests for concrete microcracks were conducted. The morphology of microcrack development under fluorescent labelling was scrutinised, and the intervals of opening widths for the examined cracks were quantified. The findings demonstrate that concrete microcracks draw surrounding fluorescent solutions into the cracks through capillary adsorption. Under UV radiation, microcracks manifest dark bands in relation to the fluorescence attachment area due to the loss of fluorescent solution around them. This band elucidates the location and morphology of the marked crack, amplifying its visual representation. Furthermore, the fluorescence selective excitation UV detection method proves effective in identifying concrete microcracks with a width as small as 0.02 mm. The improved UAV equipment was used to carry out the aerial detection experiment on the actual concrete structure. [ABSTRACT FROM AUTHOR]

Federated learning (FL) is a machine learning setting which allows multiple participants collaboratively to train a model under the orchestration of a server without disclosing their local data. Vertical federated learning (VFL) is a special structure in FL. It handles the situation where participants have the same ID space but different feature spaces. In order to guarantee the security and privacy of the local data of each participant, homomorphic encryption (HE) is often used to transmit intermediate parameters or data during the training process. In most VFL frameworks, a trusted third-party server is necessary because the plaintexts of the parameters need to be revealed for the computation. However, it is hard to find such a credible entity in the real world. Existing methods for solving this problem are either communication-intensive or unsuitable for multi-party scenarios. By combining secret sharing (SS) and HE, we propose a novel VFL framework without any trusted third parties called EFMVFL. It allows intermediate parameters to be transmitted among multiple parties without revealing the plaintexts. EFMVFL is applicable to generalized linear models (GLMs) and supports flexible expansion to multiple participants. Extensive experiments under Logistic Regression and Poisson Regression show that our framework is outstanding in communication (reduced by 3.2×– 6.8×) and efficiency (accelerated by 1.6×– 3.1×). [ABSTRACT FROM AUTHOR]