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 Ti3C2Tx MXene nanosheets and the microscale layered aerogel walls enable the bidirectional aerogel to achieve a wide EAB of 8.58 GHz at a thickness of 2.1 mm. This is ascribed to the numerous aligned nanosheets and layered aerogel walls perpendicular to the incident EMs, facilitating the conversion of electromagnetic energy into electrical energy. Furthermore, on the macroscale, the multilayer bidirectional aerogel with non-gradient structures effectively resolves the conflict between impedance matching and energy loss, resulting in an ultrawide EAB of 9.41 GHz at a thickness of 3 mm. This innovative design of electric-field-assisted multilayer bidirectional aerogels with multiscale structural coupling may provide feasible and effective pathways for the development of advanced EM absorption materials.

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. The output performance of friction power generation increases with the increase in F content, and the obtained polyacidic ligand materials can be used to construct self-powered corrosion protection systems, which can effectively protect metallic materials from corrosion.

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 10.1002/chem.202302217.

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). The correlation between the optical rotation and the absolute configuration of the UICs was finally established, showcasing the power of absolute structure determination by SCXRD, which is essential in structural chemistry and pharmaceutical research.

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. Objective: The study intended to investigate the effects of using narrative care during high flux hemodialysis (HFHD) on clinical outcomes and prognosis of quality of life (QoL) for patients with chronic renal failure (CRF), to provide a reliable theoretical reference for future clinical treatment. Design: The research team performed a randomized controlled trial. Setting: The study took place at the Blood Purification Center at the Affiliated Hospital of Medical School at Ningbo University in Ningbo, Zhejiang, China. Participants: Participants were 78 patients with CRF who received treat with HFHD at the hospital between January 2021 and August 2022. Intervention: The research team divided participants into two groups using the random number table method, with 39 participants in each group: (1) and intervention group who received narrative nursing care and (2) a control group who receive the usual care. Outcome Measures: The research team: (1) evaluated the clinical efficacy for both groups; (2) at baseline and postintervention, measured participants' blood creatinine (SCr) and blood urea nitrogen (BUN) using blood sampling; (3) counted adverse effects; (4) investigated participants' nursing satisfaction postintervention; (5) at baseline and postintervention, assessed psychology and QoL using the Self-Assessment Scale for Anxiety (SAS), the Self-Assessment Scale for Depression (SDS), and the General Quality of Life Inventory (GQOLI-74) scale. Results: No statistically significant differences existed between the groups in terms of efficacy or renal function postintervention (P > .05). The incidence of adverse reactions was significantly lower in the intervention group than in the control group postintervention (P = .033), and the group's nursing satisfaction was significantly higher (P = .042). In addition, participants' SAS and SDS scores decreased significantly in the intervention group postintervention (P < .05), while no change occurred for the control group (P > .05). Finally, the GQOLI-74 scores were all significantly higher in the intervention group than in the control group. Conclusions: Narrative care can effectively enhance the safety of HFHD treatment in CRF patients and reduce patients' negative emotions postintervention, which is important for improving their QoL.

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. METHODS: This study was conducted in 16 MMT clinics in Guangdong, China. Data on the clients' demographic characteristics; drug-related behavior; HIV, HCV, and urine morphine test results; and daily methadone doses were collected. The outcomes were time to recurrent relapse and time to dropout. A joint frailty model was used to explore factors jointly associated with recurrent relapse and dropout. The hazard ratios (HRs) of the covariates in the multivariable model were adjusted, with HR > 1 indicating a faster time to recurrent relapse and dropout. RESULTS: Among 1539 clients, 39.5% had ≥ 2 relapse events, and 90.8% of the clients dropped out. A high attendance rate was protective for recurrent relapse (HR50-80%=0.63, 95% CI: 0.51, 0.79; HR>80%=0.35, 95% CI: 0.28, 0.44) and dropout (HR50-80%=0.56, 95% CI: 0.47, 0.68; HR>80%=0.27, 95% CI: 0.23, 0.33). Being married (HR=0.80, 95% CI: 0.67, 0.96), having a fair relationship with family (HR=0.79, 95% CI: 0.67, 0.93) and drug injection (HR=0.80, 95% CI: 0.67, 0.96) were also protective for recurrent relapse. Female (HR=0.64, 95% CI: 0.50, 0.82) and a high methadone dose (≥60 ml/day; HR=0.79, 95% CI: 0.65, 0.96) were protective for dropout, and a longer traveling time to the clinic (>60 min; HR=1.59, 95% CI: 1.20, 2.10) was associated with an increased risk of dropout. CONCLUSIONS: It is common for clients to experience recurrent relapse and dropout. The findings suggest that MMT clinics should provide holistic interventions and appropriate methadone doses for clients to improve treatment compliance.

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. METHODS: A retrospective study was conducted from 2006 to 2017 at nine MMT clinics in Guangdong, China, involving 549 participants. The end point was the first relapse within 12 months of the start of tapering. Relapse risks before tapering for each participant were determined from a Cox model. RESULTS: Out of 549 participants, 173 (31.5 %) relapsed within 12 months after tapering. Findings indicated that a taper dose of less than 5 mg/week is better than other taper doses. Subpopulation treatment effect pattern plot (STEPP) methodology revealed different tapering strategies benefit participants according to relapse risk before tapering. Overall, findings indicated that a less than 5 mg/week reduction in MMT dose is better than reductions of other amounts. For participants with a low relapse risk before tapering, a reduction of less than 2.5 mg/week in MMT dose is better than a 2.5-5 mg/week reduction. CONCLUSIONS: A taper dose of less than 5 mg/week appears to be the best dose tapering strategy for Chinese participants. Furthermore, for participants with a low relapse risk, a more gradual taper dose (less than 2.5 mg/week) works better than 2.5-5 mg/week. This benefit was not seen in participants with a high relapse risk before tapering.

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

An efficient and stereoselective CoIII -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. The allenyl alcohol products can be further converted to dihydrofurans with high stereoselectivity either in situ or under Ag-mediated cyclization conditions. The allenyl silyl group can also be transferred to the adjacent alcohol by a Brook rearrangement. Moreover, a mechanism for the transformation is proposed supported by X-ray structural characterization of a cobaltacycle intermediate.

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. Exposure to the BOG was established by triple differences measured by age group, survey period and whether child participants were living in BOG areas or not, respectively. Children's growth was assessed by binary variables of stunting, underweight, overweight and obesity. The difference-in-difference-in-differences (DDD) method was used to estimate the association between the BOG and children's growth. RESULTS: DDD estimates showed that the BOG was significantly associated with decreased risks of children's underweight (OR 0.12; 95% CI 0.02 to 0.69) and overweight (OR 0.43; 95% CI 0.19 to 0.98) after controlling for multiple covariates in fractional polynomial models. There was significant sex heterogeneity with regard to the association between BOG and obesity, that is, lower odds of obesity (OR 0.24; 95% CI 0.06 to 0.94) were found in female children but not in male children. CONCLUSION: The BOG was positively associated with healthier growth of children including decreased risks of both undernutrition and overnutrition. More attention should be given to the improvement of health surveillance and services before and after sporting events so that the active role of such mega-events in the lasting well-being of the public can be determined in more detail.

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. Method: This retrospective study used data collected from seven MMT clinics in Guangdong Province, China, from January 2010 to April 2017. Newly enrolled participants who received 6 (n = 903) and 12 (n = 710) months of consecutive treatment with complete data were included. We selected significant risk factors for relapse through the group lasso regression and then incorporated them into Bayesian networks to reveal relationships between factors and predict the relapse risk. Results: The results showed that participants who received 6-month treatment had a lower relapse rate (32.0%) than those of 12-month treatment (39.0%, P < 0.05). Factors including personal living status and daily methadone dose were only influential to those who received the 6-month treatment. However, age, age at the initial drug use, HIV infection status, sexual behaviors, and continuous treatment days were common factors of both durations. The highest relapse risk for those after the 6-month treatment was inferred as 66.7% while that of the 12-month treatment was 83.3%. Farmers and those who have high accessibility to MMT services may require additional attention. Conclusion: It is necessary to implement targeted interventions and education based on the treatment durations of participants to decrease the relapse rate. Meanwhile, those about HIV/sexually transmitted infection prevention and anti-narcotics should be held in the whole process.

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

Despite notable progress, olefin metathesis methods for preparation of ( Z)-α,ß-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,ß-unsaturated carbonyl compounds in up to 81% yield and ≥98:2 Z/ E ratio. We show that through the use of a complex bearing an unsaturated N-heterocyclic carbene (NHC) ligand, for the first time, products derived from the more electron-deficient esters, acids, and Weinreb amides (vs primary or secondary amides) can be synthesized efficiently and with high stereochemical control. The importance of the new advance to synthesis of bioactive compounds is illustrated through two representative applications: an eight-step, 15% overall yield, and completely Z-selective route leading to an intermediate that may be used in synthesis of stagonolide E (vs 11 steps, 4% overall yield and 91% Z, previously), and a five-step, 25% overall yield sequence to access a precursor to dihydrocompactin (vs 13 steps and 5% overall yield, formerly).

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. The method has considerable scope, as olefins containing an alcohol, an aldehyde, an epoxide, a carboxylic acid, or an alkenyl group may be used. Mechanistic models that account for the observed levels and trends in efficiency and stereochemical control are provided, based on DFT studies.

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. Cross-metathesis with olefins that contain a carboxylic acid, an aldehyde, an allylic alcohol, an aryl olefin, an α substituent, or amino acid residues was carried out to generate the desired products in 47-88% yield and 90:10 to >98:2 Z:E selectivity. Transformations were equally efficient and stereoselective with a ∼70:30 Z-:E-butene mixture, which is a byproduct of crude oil cracking. The in situ methylene capping strategy was used with the same Ru catechothiolate complex (no catalyst modification necessary) to perform ring-closing metathesis reactions, generating 14- to 21-membered ring macrocyclic alkenes in 40-70% yield and 96:4-98:2 Z:E selectivity; here too, reactions were more efficient and Z-selective than when the other catalyst classes are employed. The utility of the approach is highlighted by applications to efficient and stereoselective syntheses of several biologically active molecules. This includes a platelet aggregate inhibitor and two members of the prostaglandin family of compounds by catalytic cross-metathesis reactions, and a strained 14-membered ring stapled peptide by means of macrocyclic ring-closing metathesis. The approach presented herein is likely to have a notable effect on broadening the scope of olefin metathesis, as the stability of methylidene complexes is a generally debilitating issue with all types of catalyst systems. Illustrative examples of kinetically controlled E-selective cross-metathesis and macrocyclic ring-closing reactions, where E-butene serves as the methylene capping agent, are provided.

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

A palladium-catalyzed asymmetric [3+2] cycloaddition reaction of vinylaziridines with α,ß-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.