Bimetal-Organic Frameworks Incorporating Both Hard and Soft Base Active Sites for Heavy Metal Ion Capture.

The design and synthesis of stable porous materials capable of removing both hard and soft metal ions pose a significant challenge. In this study, a novel metal-organic framework (MOF) adsorbent named CdK-m-COTTTB was developed. This MOF material was constructed using sulfur-rich m-cyclooctatetrathiophene-tetrabenzoate (m-H4COTTTB) as the organic ligand and oxygen-rich bimetallic clusters as the inorganic nodes. The incorporation of both soft and hard base units within the MOF structure enables effective removal of various heavy metal ions, including both soft and hard acid species. In single-component experiments, the adsorption capacity of CdK-m-COTTTB for Pb2+, Tb3+, and Zr4+ ions reached levels of 636.94, 432.90, and 357.14 mg·g-1, respectively, which is comparable to specific MOF absorbents. The rapid adsorption process was found to be chemisorption. Furthermore, CdK-m-COTTTB exhibited the capability to remove at least 12 different metal ions in both separate and multicomponent solutions. The material demonstrated excellent acid-base stability and renewability, which are advantageous for practical applications. CdK-m-COTTTB represents the first reported pristine MOF material for the removal of both hard and soft acid metal ions. This work serves as inspiration for the design and synthesis of porous crystalline materials that can efficiently remove diverse heavy metal pollutants.

Factors related to suicidal ideation of schizophrenia patients in China: a study based on decision tree and logistic regression model.

This study aimed to investigate the factors associated with suicidal ideation in schizophrenia patients in China using decision tree and logistic regression models. From October 2020 to March 2022, patients with schizophrenia were chosen from Chifeng Anding Hospital and Daqing Third Hospital in Heilongjiang Province. A total of 300 patients with schizophrenia who met the inclusion criteria were investigated by questionnaire. The questionnaire covered general data, suicidal ideation, childhood trauma, social support, depressive symptoms and psychological resilience. Logistic regression analysis revealed that childhood trauma and depressive symptoms were risk factors for suicidal ideation in schizophrenia (OR = 2.330, 95%CI: 1.177 ~ 4.614; OR = 10.619, 95%CI: 5.199 ~ 21.688), while psychological resilience was a protective factor for suicidal ideation in schizophrenia (OR = 0.173, 95%CI: 0.073 ~ 0.409). The results of the decision tree model analysis demonstrated that depressive symptoms, psychological resilience and childhood trauma were influential factors for suicidal ideation in patients with schizophrenia (p < 0.05). The area under the ROC for the logistic regression model and the decision tree model were 0.868 (95% CI: 0.821 ~ 0.916) and 0.863 (95% CI: 0.814 ~ 0.912) respectively, indicating excellent accuracy of the models. Meanwhile, the logistic regression model had a sensitivity of 0.834 and a specificity of 0.743 when the Youden index was at its maximum. The decision tree model had a sensitivity of 0.768 and a specificity of 0.8. Decision trees in combination with logistic regression models are of high value in the study of factors influencing suicidal ideation in schizophrenia patients.

Hydrophobic and porous carbon nanofiber membrane for high performance solar-driven interfacial evaporation with excellent salt resistance.

Interfacial evaporation has recently received great interest from both academia and industry to harvest fresh water from seawater, due to its low cost, sustainability and high efficiency. However, state-of-the-art solar absorbers usually face several issues such as weak corrosion resistance, salt accumulation and hence poor long-term evaporation stability. Herein, a hydrophobic and porous carbon nanofiber (HPCNF) is prepared by combination of the porogen sublimation and fluorination. The HPCNF possessing a macro/meso porous structure exhibits large contact angles (as high as 145°), strong light absorption and outstanding photo-thermal conversion performance. When the HPCNF is used as the solar absorber, the evaporation rate and efficiency can reach up to 1.43 kg m-2h-1 and 87.5% under one sunlight irradiation, respectively. More importantly, the outstanding water proof endows the absorber with superior corrosion resistance and salt rejection performance, and hence the interfacial evaporation can maintain a long-term stability and proceed in a variety of complex conditions. The HPCNFs based interfacial evaporation provides a new avenue to the high efficiency solar steam generation.

Flexible, superhydrophobic and multifunctional carbon nanofiber hybrid membranes for high performance light driven actuators.

Recently, a series of super-hydrophobic materials have been prepared and efforts have been made to further expand their applications, especially in electronics and smart actuators. However, it remains challenging to develop light weight, flexible and super-hydrophobic materials integrating multifunctionalities such as superior photothermal conversion, corrosion resistance, and controllable actuation. Herein, a superhydrophobic and multi-responsive carbon nanofiber (CNF) hybrid membrane with an outstanding photo-thermal effect is fabricated by electrospinning the mixture of polyacrylonitrile and nickel acetylacetonate, followed by two step heat treatment and subsequent fluorination. The superhydrophobic CNF hybrid membrane with outstanding anti-corrosion and self-cleaning performance can float on the water surface spontaneously, thus effectively reducing the motion resistance. The light driven actuation with controllable movement can be achieved by adjusting the laser irradiated location, in which the localized absorption of light is transformed into thermal energy, and hence an imbalanced surface tension is created. The multifunctional hybrid membrane also opens up an arena of applications such as freestanding flexible electronics, drug delivery, and environmental protection.

Microporous Carbon Nanofibers Derived from Poly(acrylonitrile-co-acrylic acid) for High-Performance Supercapacitors.

Carbon nanofiber (CNF)-based supercapacitors have promising applications in the field of energy storage. It is desirable, but remains challenging, to develop CNF electrode materials with large specific surface area (SSA), high specific capacitance (SC), and high power density, as well as excellent cycling stability and high reliability. Herein, acrylonitrile-acrylic acid copolymer P(AN-co-AA) was synthesized for the preparation of nitrogen-doped microporous CNFs. Thermal degradation of the AA segment leads to the formation of micropores that are distributed not only on the CNF surface, but also inside the material. The microporous structure and nitrogen content can be manipulated at the molecular level by adjusting the weight ratio between AN and AA, and the SSA and SC could reach as high as 1099 m2 g-1 and 156 F g-1 , respectively. After KOH activation, the activated CNFs have an extremely high SSA of 2117 m2 g-1 and SC of 320 F g-1 , which are among the highest values ever reported for electric double-layer supercapacitors with an alkaline electrolyte. Furthermore, the capacitance retention, which can be maintained at 99 % even after 16 000 cyclic tests, reveals outstanding durability and repeatability.

Surface engineering of a Pantoea agglomerans-derived phenylalanine aminomutase for the improvement of (S)-ß-phenylalanine biosynthesis.

A Pantoea agglomerans-derived phenylalanine aminomutase (PaPAM) was engineered to improve the biocatalytic synthesis of (S)-ß-phenylalanine, which is an important precursor of pharmaceuticals and peptidomimetics. A semi-rational design strategy based on a combination of surface-amino-acid engineering and the amino acid preference of the thermozyme was applied to counteract the enzyme trade-off between improving its activity and stability. The surface glycine, lysine and serine of PaPAM were mutated to alanine, arginine and alanine, respectively. A K340R mutant was screened with a 2.23-fold increased activity and 2.12-fold improved half-life at 50 °C over those of the wild-type PaPAM. These improvements resulted from the more stable enzymatic conformation as well as the more rigid inner loop in K340R. When tested in a whole-cell biocatalytic reaction, the (S)-ß-phenylalanine volumetric productivity of K340R reached 0.47 g/L·h (1.4-fold greater than that of the wild-type PaPAM), and the conversion rate was improved by 17% compared to that of the wild-type PaPAM. The enzymatic properties of K340R and the resulting (S)-ß-phenylalanine production are among the highest reported, and the results indicate that the described strategy is potent for engineering enzymatic stability and activity of PAM.