Interfacial chemical oxidative synthesis of multifunctional polyfluoranthene.

A novel polyfluoranthene (PFA) exhibiting strong visual fluorescence emission, a highly amplified quenching effect, and widely controllable electrical conductivity is synthesized by the direct cationic oxidative polymerization of fluoranthene in a dynamic interface between n-hexane and nitromethane containing fluoranthene and FeCl3, respectively. A full characterization of the molecular structure signifies that the PFAs have a degree of polymerization from 22-50 depending on the polymerization conditions. A polymerization mechanism at the interface of the hexane/nitromethane biphasic system is proposed. The conductivity of the PFA is tunable from 6.4 × 10-6 to 0.074 S cm-1 by doping with HCl or iodine. The conductivity can be significantly enhanced to 150 S cm-1 by heat treatment at 1100 °C in argon. A PFA-based chemosensor shows a highly selective sensitivity for Fe3+ detection which is unaffected by other common metal ions. The detection of Fe3+ likely involves the synergistic effect of well-distributed π-conjugated electrons throughout the PFA helical chains that function as both the fluorophore and the receptor units

Facile Synthesis and Versatilities of Polyanthraquinoylamine Nanofibril Bundles with Self Stability and High Carbon Yield

A facile synthesis for nanosized conducting polymers with inherent self-stability and multi-functionalities is a main challenge. Here we simply synthesize intrinsically self-stabilized nanofibril bundles of poly(1-anthraquinoylamine) (PAQ) by a template-free method. The critical polymerization parameters were studied to significantly optimize the synthesis, size, properties, and functionalities of the resulted fine nanofibrils with a diameter of ca. 30 nm and length of ~6 μm. The PAQ obtained with ammonium persulfate possesses higher polymerization yield, purer composition, higher conductivity, better melting behaviour, higher thermostability, lower burning enthalpy, and slower degradation than that with other oxidants. Furthermore, the polymer nanofibrils exhibit high self-stability, powerful redispersibility, high purity, and clean surface because of a complete avoidance of the contamination from external stabilizer. The PAQ exhibits widely controllable conductivity moving across ten orders of magnitudes from 10^-9^ to 50 S/cm, photoluminescence, lead-ion adsorbability, very high thermostability in air and extremely high char yield in nitrogen at 1000˚C. These materials would be useful as advanced materials including photoluminescent materials, highly cost-effective carbon precursors, sorbents of toxic metal ions, and cost-efficient conductive nanocomposite with low percolation threshold

Structure and high-resolution thermogravimetry of liquid-crystalline copoly(p-oxybenzoate- ethylene terephthalate-p-benzamide)

Abstract: Thermotropic liquid-crystalline copoly(ester-amide)s consisting of three units of poxybenzoate (B), ethylene terephthalate (E) and p-benzamide (A) were studied by proton nuclear magnetic resonance at 200 and 400 MHz, wide-angle X-ray diffraction, and high-resolution thermogravimetry to ascertain their molecular and supermolecular structures, thermostability and kinetics parameters of thermal decomposition in both nitrogen and air. The assignments of all resonance peaks of [ 1 H]NMR spectra for the copoly(ester-amide)s are given and the characteristics of X-ray equatorial and meridional scans are discussed. Overall activation energy data of the ®rst major decomposition have been evaluated through three calculating techniques. The thermal degradation occurs in three steps in nitrogen and air. The degradation temperatures are higher than 447°C in nitrogen and 440°C in air and increase with increasing B-unit content at a ®xed A-unit content of 5 mol%. The temperatures at the ®rst maximum weight-loss rate are higher than 455°C in nitrogen and 445°C in air and also increase with an increase in B-unit content. The ®rst maximum weight-loss rates range between 11.1 and 14.5%min À1 in nitrogen and between 11.9 and 13.5%min À1 in air. The char yields at 500°C in both nitrogen and air range from 45.8 to 54.3 wt% and increase with increasing B-unit content. But the char yields at 800°C in nitrogen and air are quite irregular with the variation of copolymer composition and testing atmosphere. The activation energy and Ln (pre-exponential factor) for the ®rst major decomposition are usually higher in nitrogen than in air and increase slightly with an increase in B-unit content at a given A-unit content of 5 mol%. The activation energy, decomposition order, and Ln (pre-exponential factor) of the thermal degradation for the copoly(esteramide)s in two testing atmospheres, are situated in the ranges of 210±292 kJmol À1 , 2.0±2.8, 33±46 min À1 , respectively. The three kinetic parameters of the thermal degradation for the aromatic copoly(esteramide)s obtained by high-resolution thermogravimetry at a variable heating rate are almost the same as those by traditional thermogravimetry at constant heating rate, suggesting good applicability of kinetic methods developed for constant heating rate to the variable heating-rate method. These results indicate that the copoly(ester-amide)s exhibit high thermostability. The isothermal decomposition kinetics of the copoly(ester-amide)s at 450 and 420°C are also discussed and compared with the results obtained based on non-isothermal high-resolution thermogravimetry

CircRNA_014511 affects the radiosensitivity of bone marrow mesenchymal stem cells by binding to miR-29b-2-5p

Hematopoietic stem cell transplantation is commonly used in patients with certain hematological or bone marrow tumors. Total body irradiation combined with chemotherapy is part of the preconditioning protocol that was the most commonly used before hematopoietic stem cell transplantation. However, total body irradiation preconditioning damages other normal cells in bone marrow. Therefore, exploring the mechanism of radiation resistance in bone marrow mesenchymal stem cells is of great significance for recovering the hematopoietic function after cell transplantation. This study aimed to demonstrate the miR-29b adsorption of circRNA_014511 and explore the effect of circRNA_014511 on radiosensitivity of bone marrow mesenchymal stem cells. In this study, circRNA_014511 overexpression vector was constructed and transfected into bone marrow mesenchymal stem cells, miR-29b-2-5p and P53 were found to be decreased, which could be reversed by miR29b-mimics. Dual luciferase reporter assay confirmed the binding of circRNA_014511 and mmu-miR-29b-2-5p. Flow cytometry analysis showed the apoptosis rate of bone marrow mesenchymal stem cells overexpressing circRNA_014511 was significantly decreased. In the circRNA_014511 transfection group, after cells were subjected to 6Gy irradiation, G2 phase arrest appeared, the expression of P21 and GADD45A was significantly decreased, and cyclin B1 was significantly increased. Colony formation assay showed the survival fraction of circRNA_014511 overexpression cells after irradiation was significantly higher than control group, and the radiosensitivity was decreased. In conclusion，our findings demonstrated that circRNA_014511 could inhibit the expression of P53 by binding miR-29b-2-5p, and decrease the radiosensitivity of bone marrow mesenchymal stem cells by affecting cell cycle and cell apoptosis

Orthogonal Subspace Learning for Language Model Continual Learning

Benefiting from massive corpora and advanced hardware, large language models (LLMs) exhibit remarkable capabilities in language understanding and generation. However, their performance degrades in scenarios where multiple tasks are encountered sequentially, also known as catastrophic forgetting. In this paper, we propose orthogonal low-rank adaptation (O-LoRA), a simple and efficient approach for continual learning in language models, effectively mitigating catastrophic forgetting while learning new tasks. Specifically, O-LoRA learns tasks in different (low-rank) vector subspaces that are kept orthogonal to each other in order to minimize interference. Our method induces only marginal additional parameter costs and requires no user data storage for replay. Experimental results on continual learning benchmarks show that our method outperforms state-of-the-art methods. Furthermore, compared to previous approaches, our method excels in preserving the generalization ability of LLMs on unseen tasks.Comment: EMNLP 2023 finding

2-Fluoro-N′-(2-hy­droxy­benzyl­idene)benzohydrazide

In the title compound, C14H11FN2O2, an intra­molecular O—H⋯N hydrogen bond influences the mol­ecular conformation; the two benzene rings form a dihedral angle of 18.4 (3)°. The F atom is disordered over two positions in a 0.717 (5):0.283 (5) ratio. In the crystal, inter­molecular N—H⋯O hydrogen bonds link the mol­ecules into chains extending along the c axis

2-Fluoro-N′-(2-meth­oxy­benzyl­idene)benzohydrazide

The mol­ecule of the title compound, C15H13FN2O2, exists in a trans configuration with respect to the methyl­idene unit. The two benzene rings form a dihedral angle of of 64.7 (2)°. In the crystal, mol­ecules are linked through N—H⋯O hydrogen bonds into chains propagating along the c axis