Multidimensional Engineering Induced Interfacial Polarization by in-Situ Confined Growth of MoS2 Nanosheets for Enhanced Microwave Absorption.

Interface design has enormous potential for the enhancement of interfacial polarization and microwave absorption properties. However, the construction of interfaces is always limited in components of a single dimension. Developing systematic strategies to customize multidimensional interfaces and fully utilize advantages of low-dimensional materials remains challenging. Two-dimensional transition metal dichalcogenides (TMDCs) have garnered significant attention owing to their distinctive electrical conductivity and exceptional interfacial effects. In this study, a series of hollow TMDCs@C fibers are synthesized via sacrificial template of CdS and confined growth of TMDCs embedded in the fibers. The complex permittivity of the hollow TMDCs@C fibers can be adjusted by tuning the content of CdS templates. Importantly, the multidimensional interfaces of the fibers contribute to elevating the microwave absorption performance. Among the hollow TMDCs@C fibers, the minimum reflection loss (RLmin) of the hollow MoS2@C fibers can reach -52.0 dB at the thickness of 2.5 mm, with a broad effective absorption bandwidth of 4.56 GHz at 2.0 mm. This work establishes an alternative approach for constructing multidimensional coupling interfaces and optimizing TMDCs as microwave absorption materials.

Bioactive Compounds from the Stems of Clausena lansium.

In view of the significant neuroprotective effect of Clausena lansium, we continued to separate the n-butanol and the water extracts from the stems of C. lansium in order to find the leading compounds with significant activity. Two new phenolic glycosides, Clausenolside A-B (1-2), one new pair of phenolic enantiomers (3a, 3b), and two new monoterpenoids, clausenapene A-B (4-5), together with twelve known analogues (6-17) were isolated from the stems of C. lansium. Compounds 1-17 were obtained from C. lansium for the first time. Compounds 3a, 3b, 4, 16, and 17 showed strong or moderate potential neuroprotective effects on inhibited PC12 cell injury induced by okadaic acid, and compound 9 exhibited strong potential hepatoprotective activities. Their structures were elucidated on the basis of spectroscopic analyses, including UV, IR, NMR experiments, and electronic circular dichroism (ECD) spectra.

Carbazole and amide alkaloids from the stems of Clausena lansium.

Two new carbazole alkaloids, claulansine S (1) and claulansine T (2), and one new amide alkaloid, clauamide A (3), together with four known analogues (4-7) were isolated from the stems of Clausena lansium. Their structures were elucidated on the basis of spectroscopic analyses, including UV, IR, and NMR experiments (HSQC, HMBC, and NOE experiments). Compounds 4 and 6 showed moderate hepatoprotective activities.

Career choice motivation and professionalism in medical students in China: a gender-stratified analysis.

OBJECTIVE: To examine the associations between career choice motivation and professionalism among medical students based on gender in the context of COVID-19. DESIGN: Cross-sectional study. SETTING: The study was conducted at a medical school in China. METHODS: A total of 1421 second-year to fourth-year medical students participated in the survey using cluster sampling. They were asked to complete questionnaires on demographic information, career choice motivation and professionalism. Linear regression models were used to analyse the relationship between career choice motivations and professionalism based on gender differences. RESULTS: Female medical students outperformed males in professionalism (p<0.001). Third-year medical students have the lowest level of professionalism irrespective of gender. In addition, females have more intrinsic career choice motivation than males. Students motivated by personal interest had the highest level of professionalism, while those who go with the flow had the lowest. According to the linear regression analysis, the motivation advice from parents was the factor of professionalism in male medical students (p<0.05). However, the motivation go with the flow negatively influenced the professionalism of female medical students (p<0.05). CONCLUSION: The level of professionalism differed between genders based on different career choice motivations. Career choice motivation can be used as an entry point for professionalism education among medical students. Targeted interventions should be implemented to improve professionalism, especially for male medical students and unmotivated students.

Customized Pore Creation Strategies for Hyperelastic, Robust, Insulating Multifunctional MXene Aerogels for Microwave Absorption.

The construction of heterogeneous microstructure and the selection of multicomponents have turned into a research hotspot in developing ultralight, multifunctional, high-efficiency electromagnetic wave absorbing (EMA) materials. Although aerogels are promising materials to fulfill the above requirements, the increase in functional fillers inevitably leads to the deterioration of intrinsic properties. Tuning the electromagnetic properties from the structural design point of view remains a difficult challenge. Herein, we design customized pore creation strategies via introducing sacrificial templates to optimize the conductive path and construct the discontinuous dielectric medium, increasing dielectric loss and achieving efficient microwave absorption properties. A 3D porous composite (MEM) was crafted, which encapsulated an EVA/FeCoNi (EVA/MNPs) framework with Ti3C2Tx MXene coating by employing a direct heated cross-linking and immersion method. Controllable adjustment of the conductive network inside the porous structure and regulation of the dielectric character are achieved by porosity variation. Eventually, the MEM-5 with a porosity of 66.67% realizes RLmin of -39.2 dB (2.2 mm) and can cover the entire X band. Moreover, through off-axis electronic holography and the calculation of conduction loss and polarization loss, the dielectric property is deeply investigated, and the inner mechanism of optimization is pointed out. Thanks to the inherent characteristic of EVA and the porous structure, MEM-5 showed excellent thermal insulating and superior compressibility, which can maintain 60 °C on a 90-100 °C continuous heating stage and reached a maximum compressive strength of 60.12 kPa at 50% strain. Conceivably, this work provides a facile method for the fabrication of highly efficient microwave absorbers applied under complex conditions.

Physical function, ADL, and depressive symptoms in Chinese elderly: Evidence from the CHARLS.

Background: Depressive symptoms are a serious public health problem that affects the mental health of older adults. However, current knowledge of the association between ADL disability and physical dysfunction and depressive symptoms in Chinese adults is insufficient. We intend to analyze the association between physical function, ADL, and depressive symptoms in older Chinese adults. Methods: The data obtained from the China Health and Retirement Longitudinal Survey (2015 and 2018) (CHARLS). This includes 3,431 in 2015 and 3,258 in 2018 over the age of 60. Comparing 2015 and 2018 data, multivariate logistic regression models were used to explore the relationship between physical function, ADL, and depressive symptoms in urban and rural older adults, adjusting for sociodemographic factors associated with depression in older adults. Results: The prevalence of depressive symptoms among older adults in China was 33.8 percent in 2015 and 50.6 percent in 2018. In baseline data from 2015 and 2018, residence, gender, marital status, drinking, physical function, ADL, and self-rated health were all found to be significantly associated with depressive symptoms in older adults. The differences in physical function, ADL and depressive symptoms among older adults in 2015 and 2018 were further analyzed based on urban and rural stratification. Both physical dysfunction and ADL disability were significantly associated with depressive symptoms in rural older adults in 2015 and 2018. And in urban areas, ADL was found to be significantly associated with depressive symptoms in urban older adults. Multivariate logistic regression analysis demonstrated that ADL disability was significantly associated with depressive symptoms among older adults in both urban and rural areas. Physical dysfunction was only significant in rural areas with depressive symptoms. The alpha level was instead set to 0.05 for all statistical tests. Conclusion: Rural, female, 60-70 years of age, primary school or below, married, non-smoking, non-drinking, physical dysfunction, ADL disability and self-rated poor health make-up a higher proportion of depressed older adults. ADL disability and physical dysfunction were more likely to be associated with depressive symptoms in rural Chinese older adults. Therefore, the physical and mental health of rural elderly should be of concern. The rural older adults should receive additional support from the government and society.

High-Entropy Enhanced Microwave Attenuation in Titanate Perovskites.

High-entropy oxides (HEOs), which incorporate multiple-principal cations into single-phase crystals and interact with diverse metal ions, extend the border for available compositions and unprecedented properties. Herein, a high-entropy-stabilized (Ca0.2 Sr0.2 Ba0.2 La0.2 Pb0.2 )TiO3  perovskite is reported, and the effective absorption bandwidth (90% absorption) improves almost two times than that of BaTiO3 . The results demonstrate that the regulation of entropy configuration can yield significant grain boundaries, oxygen defects, and an ultradense distorted lattice. These characteristics give rise to strong interfacial and defect-induced polarizations, thus synergistically contributing to the dielectric attenuation performance. Moreover, the large strains derived from the strong lattice distortions in the high-entropy perovskite offer varied transport for electron carriers. The high-entropy-enhanced positive/negative charges accumulation around grain boundaries and strain-concentrated location, quantitatively validated by electron holography, results in unusual dielectric polarization loss. This study opens up an effective avenue for designing strong microwave absorption materials to satisfy the increasingly demanding requirements of advanced and integrated electronics. This work also offers a paradigm for improving other interesting properties for HEOs through entropy engineering.

Self-Healing Liquid Metal Magnetic Hydrogels for Smart Feedback Sensors and High-Performance Electromagnetic Shielding.

Hydrogels exhibit potential applications in smart wearable devices because of their exceptional sensitivity to various external stimuli. However, their applications are limited by challenges in terms of issues in biocompatibility, custom shape, and self-healing. Herein, a conductive, stretchable, adaptable, self-healing, and biocompatible liquid metal GaInSn/Ni-based composite hydrogel is developed by incorporating a magnetic liquid metal into the hydrogel framework through crosslinking polyvinyl alcohol (PVA) with sodium tetraborate. The excellent stretchability and fast self-healing capability of the PVA/liquid metal hydrogel are derived from its abundant hydrogen binding sites and liquid metal fusion. Significantly, owing to the magnetic constituent, the PVA/liquid metal hydrogel can be guided remotely using an external magnetic field to a specific position to repair the broken wires with no need for manual operation. The composite hydrogel also exhibits sensitive deformation responses and can be used as a strain sensor to monitor various body motions. Additionally, the multifunctional hydrogel displays absorption-dominated electromagnetic interference (EMI) shielding properties. The total shielding performance of the composite hydrogel increases to ~ 62.5 dB from ~ 31.8 dB of the pure PVA hydrogel at the thickness of 3.0 mm. The proposed bioinspired multifunctional magnetic hydrogel demonstrates substantial application potential in the field of intelligent wearable devices.

Hierarchical Flower-like Sulfides with Increased Entropy for Electromagnetic Wave Absorption.

The concept of high entropy is considered promising to enhance electromagnetic wave absorption properties. However, preparing high-entropy sulfides with unique structures for high-performance electromagnetic absorption remains a challenge. In this study, hierarchical porous flower-like dual-phase sulfides were designed with increased entropy and fabricated using a versatile approach. The porous flower configuration enhanced the scattering of electromagnetic waves and the impedance-matching characteristics. Additionally, the effect of high entropy induced diverse defects that were favorable for electromagnetic wave dissipation in dual-phase sulfides. The design of the dual-phase structure generated strong interface polarization, and the composition and content of the phases exhibited clear changes with the increase in the number of metal elements. Interestingly, apparent lattice distortions, defects, and shear strains were directly observed near the dual-phase interface of millerite (102) and pyrite (220) planes, facilitating the occurrence of dipole polarization. Consequently, the developed dual-phase high-entropy sulfide exhibited outstanding microwave absorption properties. The minimum reflection loss value of (FeCoNiCuZn)S was -45.8 dB at a thickness of 1.5 mm, and the optimal effective absorption bandwidth was 3.8 GHz at a thickness of 1.4 mm thickness. Thus, the design of high-entropy sulfides brings meaningful guidance for tuning the wave absorption properties in sulfides.

Neuroprotective triterpene saponins from the leaves of Panax notoginseng.

Two new triterpene saponins, namely notoginsenoside Ng5 (1) and notoginsenoside Ng6 (2) were isolated from the leaves of Panax notoginseng, along with five known ones. Their structures were determined by chemical methods, NMR and X-ray experiments. The absolute configuration of compound 3 with four sugar units was confirmed by single crystal X-ray analysis. Compounds 2-4 and 6 inhibited PC12 cell damage induced by serum deprivation, and increased cell viability from 58.7 ± 6.7% to 66.7 ± 4.5%, 76.1 ± 6.1%, 64.7 ± 5.2% and 67.2 ± 5.0% at 10 µM, respectively.

Bioactive carbazole alkaloids from the stems of Clausena lansium.

Seven new carbazole alkaloids, claulansines L-R (1-7), and six known analogues (8-13) were isolated from the stems of Clausena lansium. Their structures were elucidated on the basis of spectroscopic analyses, including UV, IR, and NMR experiments (HSQC, HMBC, and NOE experiment). Compound 7 showed moderate anti-inflammatory activities. Compounds 3, 5, 6, 8, and 12 exhibited moderate hepatoprotective activities.