Bidirectional, Multilayer MXene/Polyimide Aerogels for Ultra-Broadband Microwave Absorption.

To obtain high-performance electromagnetic microwave (EM) absorption materials with broad effective absorption bandwidth (EAB) and reduced thickness, designing structures has proved to be a promising way. Herein, ultra-broadband multilayer bidirectional MXene/polyimide EM absorption aerogels containing multi-structures on scales ranging from the micro- to the macroscale are produced with the aid of electric and temperature fields. On the microscale, under the action of electric force and temperature gradient, the ordered structures made of aligned TiCT MXene nanosheets and the microscale layered aerogel walls enable the bidirectional aerogel to achieve a wide EAB of 8.

Multi-F-Structured MOF Materials Enhance Nanogenerator Output Performance for Corrosion Protection of Metallic Materials.

MOF (metal organic framework) materials have been used as functional materials in a number of fields due to their diverse spatial tunability, which produces rich porous structures with stable and continuous pores and a high specific surface area. A triboelectric nanogenerator can convert trace mechanical energy into electrical energy, and the application of MOF materials to triboelectric nanogenerators has been intensively studied. In this work, we report on two MOFs with similar spatial structures, and the modulation of the end microstructures was achieved using the difference in F content.

Determination of the Handedness of Urea Inclusion Compounds.

Invited for the cover of this issue is the group of Bo Wang at Biogen. The image depicts the sectored chiral domains of urea inclusion compounds. Read the full text of the article at 10.

Determination of the Handedness of Urea Inclusion Compounds.

Since the discovery of urea inclusion compounds (UICs) in 1940, the handedness of this chiral helical system has not been established experimentally. Here three UIC systems containing only light atoms were studied. The optical rotations were first measured, and the absolute structures of the enantiomorphic domains of three UICs were determined by single crystal X-ray diffraction (SCXRD).

Effects of High-flux Hemodialysis With Narrative Care on Clinical Efficacy and Prognostic Quality of Life of Patients With Chronic Renal Failure.

Context: Chronic renal failure (CRF) is the outcome of the continuous progression of various chronic kidney diseases. Effective treatment of a wide range of diseases may require decreasing patients' negative emotions and enhancing their disease resilience. Narrative care focuses on patients' inner awareness, feelings, and experience of a disease, stimulating positive energy in the face of it.

The risk assessment of relapse among newly enrolled participants in methadone maintenance treatment: A group-LASSO based Bayesian network study.

Background: Relapse is a great barrier to improving the effectiveness of methadone maintenance treatment (MMT). Participants with different treatment durations could vary in their compliance with MMT, which may lead to different levels of relapse risk. This study aims to identify the risk factors for relapse and assess the relapse risk of MMT participants of different treatment durations.

Exploring factors jointly associated with recurrent relapse and dropout of methadone maintenance treatment clients in Guangdong, China: A retrospective cohort study.

Background: Clients receiving methadone maintenance treatment (MMT) may experience multiple relapses, which may lead to dropout. However, previous studies mostly only explored the influencing factors of relapse or dropout separately. In this study, we investigated the influencing factors jointly associated with both recurrent relapse and dropout.

Exploration of dose tapering strategies for methadone maintenance treatment based on relapse risks: A subpopulation treatment effect pattern plot (STEPP) analysis.

Background: Half of methadone maintenance treatment (MMT) participants experience a tapering phase, however, the guidelines vary from country to country and lack individualized strategies based on relapse risk. A detailed and individualized tapering strategy is needed in China. This study aims to explore dose tapering strategies for Chinese individuals with different relapse risks.

Stereoselective Synthesis of Allenyl Alcohols by Cobalt(III)-Catalyzed Sequential C-H Bond Addition to 1,3-Enynes and Aldehydes.

An efficient and stereoselective Co -catalyzed sequential C-H bond addition to 1,3-enynes and aldehydes is disclosed. This transformation represents the first example of sequential C-H bond additions to 1,3-enynes and a second coupling partner and provides the first example of preparing allenes by C-H bond addition to 1,3-enynes. A wide range of aldehydes, C-H bond substrates and 1,3-enynes with large substituents on the alkynes are effective substrates.

Association between Olympic Games and children's growth: evidence from China.

Objectives: To estimate the association between the 2008 Beijing Olympic Games (BOG) and growth of children in China.

Methods: A total sample of 6 951 children aged 3-10 years were included, among which 3 201 were interviewed in 2014 and 3 750 were interviewed in 2018. The BOG was used as a natural experiment.

Ru-Based Catechothiolate Complexes Bearing an Unsaturated NHC Ligand: Effective Cross-Metathesis Catalysts for Synthesis of ( Z)-α,β-Unsaturated Esters, Carboxylic Acids, and Primary, Secondary, and Weinreb Amides.

Despite notable progress, olefin metathesis methods for preparation of ( Z)-α,β-unsaturated carbonyl compounds, applicable to the synthesis of a large variety of bioactive molecules, remain scarce. Especially desirable are transformations that can be promoted by ruthenium-based catalysts, as such entities would allow direct access to carboxylic esters and amides, or acids (in contrast to molybdenum- or tungsten-based alkylidenes). Here, we detail how, based on the mechanistic insight obtained through computational and experimental studies, a readily accessible ruthenium catechothiolate complex was found that may be used to generate many α,β-unsaturated carbonyl compounds in up to 81% yield and ≥98:2 Z/ E ratio.

Synthesis of Z- or E-Trisubstituted Allylic Alcohols and Ethers by Kinetically Controlled Cross-Metathesis with a Ru Catechothiolate Complex.

The first examples of kinetically controlled cross-metathesis reactions that generate Z- or E-trisubstituted alkenes are disclosed. Transformations are catalyzed by ≤6.0 mol % of a Ru catechothiolate complex and afford trisubstituted allylic alcohols and ethers in up to 81% yield and >98% stereoisomeric purity.

In Situ Methylene Capping: A General Strategy for Efficient Stereoretentive Catalytic Olefin Metathesis. The Concept, Methodological Implications, and Applications to Synthesis of Biologically Active Compounds.

In situ methylene capping is introduced as a practical and broadly applicable strategy that can expand the scope of catalyst-controlled stereoselective olefin metathesis considerably. By incorporation of commercially available Z-butene together with robust and readily accessible Ru-based dithiolate catalysts developed in these laboratories, a large variety of transformations can be made to proceed with terminal alkenes, without the need for a priori synthesis of a stereochemically defined disubstituted olefin. Reactions thus proceed with significantly higher efficiency and Z selectivity as compared to when other Ru-, Mo-, or W-based complexes are utilized.

Highly diastereo- and enantioselective palladium-catalyzed [3+2] cycloaddition of vinyl aziridines and α,β-unsaturated ketones.

A palladium-catalyzed asymmetric [3+2] cycloaddition reaction of vinylaziridines with α,β-unsaturated ketones, wherein the alkenes have a single activator, is realized in high diastereo- and enantioselectivity, thus affording 3,4-disubstituted pyrrolidines in high yields with excellent ee values. The introduction of a methyl group at C1 of the vinyl group the vinylaziridines greatly improves the stereochemistry of the reaction. A plausible transition state is proposed.

Pd-catalyzed allylic alkylation of dienyl carbonates with nitromethane with high C-5 regioselectivity.

A highly regioselective palladium-catalyzed allylic alkylation of dienyl esters with nitromethane has been developed, providing selective access to the C-5 attacked products. The structures of the ligands as well as the steric effect of the substrates are important factors in determining the regiochemical outcome of the reaction.

Desymmetrization of bicyclo[3.n.1]-3-one derivatives by palladium-catalyzed asymmetric allylic alkylation.

Desymmetrization of carbon nucleophiles by palladium-catalyzed asymmetric allylic alkylation has been realized for the first time. Products with three chiral centers were obtained in good yield and with high diastereo- and enantioselectivity. The method offers an efficient access to optically active tropane derivatives.