Polyborosilazane with Broadly Tunable Boron Content for SiBCN Ceramics.

The high-temperature durability of SiBCN ceramics is significantly influenced by the boron concentration and synthesis methods. Although single-source synthetic routes allow one to obtain homogeneous ceramics at the atomic level, the content of the boron element therein is limited by borane (BH3). In this study, the synthesis of carborane-substituted polyborosilazanes was performed via a simple one-pot reaction of polysilazanes with alkyne bonds on the main chain and decaborododecahydrodiacetonitrile complexes with different molar ratios. This enabled one to vary the boron content from ∼0 to 40.00 wt %. The ceramic yields were in the range of 50.92-90.81 wt %. Independently of the borane concentration, SiBCN ceramics started to crystallize at 1200 °C, and B4C appeared as a new crystalline phase with increasing boron content. The introduction of boron inhibited the crystallization of Si3N4 and increased the crystallization temperature of SiC. The presence of the B4C phase improved both thermal stability and functional properties such as neutron-shielding characteristics of the ceramics. Therefore, this research opens up new prospects for the design of novel polyborosilanzes with great application potential.

2D, 3D-QSAR study and docking of vascular endothelial growth factor receptor 3 (VEGFR3) inhibitors for potential treatment of retinoblastoma.

Background: Retinoblastoma is currently the most common malignant tumor seen in newborns and children's eyes worldwide, posing a life-threatening hazard. Chemotherapy is an integral part of retinoblastoma treatment. However, the chemotherapeutic agents used in clinics often lead to drug resistance. Thus there is a need to investigate new chemotherapy-targeted agents. VEGFR3 inhibitors are anti-tumour-growth and could be used to develop novel retinoblastoma-targeted agents. Objective: To predict drug activity, discover influencing factors and design new drugs by building 2D, 3D-QSAR models. Method: First, linear and non-linear QSAR models were built using heuristic methods and gene expression programming (GEP). The comparative molecular similarity indices analysis (COMISA) was then used to construct 3D-QSAR models through the SYBYL software. New drugs were designed by changing drug activity factors in both models, and molecular docking experiments were performed. Result: The best linear model created using HM had an R2, S2, and R2cv of 0.82, 0.02, and 0.77, respectively. For the training and test sets, the best non-linear model created using GEP had correlation coefficients of 0.83 and 0.72 with mean errors of 0.02 and 0.04. The 3D model designed using SYBYL passed external validation due to its high Q2 (0.503), R2 (0.805), and F-value (76.52), as well as its low standard error of SEE value (0.172). This demonstrates the model's reliability and excellent predictive ability. Based on the molecular descriptors of the 2D model and the contour plots of the 3D model, we designed 100 new compounds using the best active compound 14 as a template. We performed activity prediction and molecular docking experiments on them, in which compound 14.d performed best regarding combined drug activity and docking ability. Conclusion: The non-linear model created using GEP was more stable and had a more substantial predictive power than the linear model built using the heuristic technique (HM). The compound 14.d designed in this experiment has the potential for anti-retinoblastoma treatment, which provides new design ideas and directions for retinoblastoma-targeted drugs.

Polyborosilazanes with Controllable B/N Ratio for Si-B-C-N Ceramics.

Polyborosilazanes with controllable B/N ratio were synthesized using high-boron-content m-carborane, dichloromethylsilane, and hexamethydisilazane. After high-temperature pyrolysis, Si-B-C-N quaternary ceramics with SiC and B4C as the main phases were obtained. The B/N ratio in the precursors corresponded to the change in the feeding ratio of carborane and dichloromethylsilane. The effects of boron content and B/N ratio on the ceramic precursors and microphase structure in Si-B-C-N quaternary ceramics were explored in detail through a series of analytical characterization methods. A high boron content results in a significant increase in the ceramic yield (up to 71 wt%) of polyborosilazanes, and at the same time, the B/N molar ratio was regulated from 28.4:1 to 1.62:1. The appearance of the B4C structure in the Si-B-C-N quaternary ceramics through the regulation of the B/N ratio, has rarely been reported.