Amorphous Nickel Hydroxide Nanosheets with Ultrahigh Activity and Super-Long-Term Cycle Stability as Advanced Water Oxidation Catalysts

Good conductivity is conventionally considered as a typical reference standard in terms of selecting water electrolysis catalysts. Electrocatalyst research so far has focused on crystal rather than amorphous due to poor conductivity. Here, we demonstrate that the amorphous electrocatalyst made of 3D honeycomb-like amorphous nickel hydroxide (Ni­(OH)₂) nanosheets synthesized by a simple, facile, green, and low-cost electrochemistry technique possesses ultrahigh activity and super-long-term cycle stability in the oxygen evolution reaction (OER). The amorphous Ni­(OH)₂ affords a current density of 10 mA cm^–2 at an overpotential of a mere 0.344 V and a small Tafel slope of 46 mV/dec, while no deactivation is detected in the CV cycles even up to 5000 times. We also establish that the short-range order, i.e., nanophase, of amorphous creates a lot of active sites for OER, which can greatly promote the electrochemical performance of amorphous catalysts. These findings show that the conventional understanding of selecting electrocatalysts with conductivity as a typical reference standard seems out of date for developing new catalysts at the nanometer, which opens a door ever closed to applications of amorphous nanomaterials as advanced catalysts for water oxidation

Heck Alkynylation (Copper-Free Sonogashira Coupling) of Aryl and Heteroaryl Chlorides, Using Pd Complexes of <i>t</i>‑Bu₂(<i>p</i>‑NMe₂C₆H₄)P: Understanding the Structure–Activity Relationships and Copper Effects

L₂Pd­(0) and L₂Pd­(II) complexes, where L= <i>t</i>-Bu₂(<i>p</i>-NMe₂C₆H₄)­P, have been identified as efficient catalyst systems for the Heck alkynylation of a variety of aryl bromides (17 examples) and aryl/heteroaryl chlorides (31 examples) with a range of aryl- and alkyl-acetylenes in excellent yields, under relatively low Pd loadings. The single-crystal X-ray structure determination of the presumably active catalytic species, L₂Pd­(0), was carried out in this study to better understand the superior activity of the current catalyst system from a structure–activity relationship point of view. The P–Pd–P bond angle indicates that the complex is bent (174.7°) in comparison to the perfectly linear (180.0°) structure of the analogous Pd­(<i>t</i>-Bu₃P)₂. Preliminary mechanistic studies on the negative copper effect and substrate effect of aryl acetylenes were conducted to better understand the cross-coupling pathway of Heck alkynylation

Enantioselective Rh-Catalyzed Carboacylation of CN Bonds via C–C Activation of Benzocyclobutenones

Herein we describe the first enantioselective Rh-catalyzed carboacylation of oximes (imines) via C–C activation. In this transformation, the benzocyclobutenone C1–C2 bond is selectively activated by a low valent rhodium catalyst and subsequently the resulting two Rh–C bonds add across a CN bond, which provides a unique approach to access chiral lactams. A range of polycyclic nitrogen-containing scaffolds were obtained in good yields with excellent enantioselectivity. Further derivatization of the lactam products led to a rapid entry to various novel fused heterocycles

Enantioselective Rh-Catalyzed Carboacylation of CN Bonds via C–C Activation of Benzocyclobutenones

Herein we describe the first enantioselective Rh-catalyzed carboacylation of oximes (imines) via C–C activation. In this transformation, the benzocyclobutenone C1–C2 bond is selectively activated by a low valent rhodium catalyst and subsequently the resulting two Rh–C bonds add across a CN bond, which provides a unique approach to access chiral lactams. A range of polycyclic nitrogen-containing scaffolds were obtained in good yields with excellent enantioselectivity. Further derivatization of the lactam products led to a rapid entry to various novel fused heterocycles

Quantitative analysis of six lignans in fruits with different colours of <i>Schisandra chinensis</i> by HPLC

<div><p>A simple and rapid high-performance liquid chromatography method was utilised for the simultaneous determination of six major lignans in <i>Schisandra chinensis</i> with different colours continuously for the next 2 years. Six lignans were successfully separated on a C₁₈ column at 254 nm using a gradient of acetonitrile and water. The assay was applied for analysing six lignans in the different colours of fruits of <i>S. chinensis</i> such as red, pink or white, and the component stability for the next 2 years was also detected. The result indicated that the total content of lignans in fruits with different colours varied remarkably, which was relatively high in red fruits, followed by white fruits and the lowest in pink fruits. Moreover, the contents of lignans in the samples of <i>S. chinensis</i> examined for the next 2 years changed irregularly and marginally.</p></div

Enantioselective Rh-Catalyzed Carboacylation of CN Bonds via C–C Activation of Benzocyclobutenones

Herein we describe the first enantioselective Rh-catalyzed carboacylation of oximes (imines) via C–C activation. In this transformation, the benzocyclobutenone C1–C2 bond is selectively activated by a low valent rhodium catalyst and subsequently the resulting two Rh–C bonds add across a CN bond, which provides a unique approach to access chiral lactams. A range of polycyclic nitrogen-containing scaffolds were obtained in good yields with excellent enantioselectivity. Further derivatization of the lactam products led to a rapid entry to various novel fused heterocycles

The loss as the training of the neural network.

Higher vocational education is the core component of China’s national education system and shoulders the mission of cultivating high-skilled and applied talents. The wide application of Massive Open Online Courses (MOOCs) has effectively improved the curriculum system of China’s higher vocational education. In the meantime, some MOOCs suffer from poor course quality. Therefore, from the perspective of sustainable course quality improvement, we propose a data-driven framework for mining and analyzing student reviews in China’s higher vocational education MOOCs. In our framework, we first mine multi-level student demands hidden in MOOC reviews by combining web crawlers and text mining. Then we use an artificial neural network and the KANO model to classify the extracted student demands, thereby designing effective and sustainable MOOC quality improvement strategies. Based on the real data from China’s higher vocational education MOOCs, we validate the effectiveness of the proposed data-driven framework.</div

The KANO model for MOOCs in higher vocational education.

The KANO model for MOOCs in higher vocational education.</p

Relationship map of student demands.

Higher vocational education is the core component of China’s national education system and shoulders the mission of cultivating high-skilled and applied talents. The wide application of Massive Open Online Courses (MOOCs) has effectively improved the curriculum system of China’s higher vocational education. In the meantime, some MOOCs suffer from poor course quality. Therefore, from the perspective of sustainable course quality improvement, we propose a data-driven framework for mining and analyzing student reviews in China’s higher vocational education MOOCs. In our framework, we first mine multi-level student demands hidden in MOOC reviews by combining web crawlers and text mining. Then we use an artificial neural network and the KANO model to classify the extracted student demands, thereby designing effective and sustainable MOOC quality improvement strategies. Based on the real data from China’s higher vocational education MOOCs, we validate the effectiveness of the proposed data-driven framework.</div

The accuracy as the training of the neural network.

The accuracy as the training of the neural network.</p