Highly Durable Silicone-Based Elastomers Achieved Through the Synergy of Bi-Incompatible Soft Segments and Multi-Scale Hydrogen Bonds.

Developing a silicone elastomer with high strength, exceptional toughness, good crack tolerance, healability, and recyclability, poses significant challenges due to the inherent trade-offs between these properties. Herein, the design of silicone-based elastomers with a nanoscopic microphase separation structure and comprehensive mechanical properties is achieved by combining bi-incompatible soft segments and multi-scale hydrogen bonds. The formation of multi-scale hydrogen bonds involving urethane, urea, and 2-ureido-4[1H]-pyrimidinone (UPy) facilitates efficient reversible crosslinking of the synthesized polymer containing thermodynamically incompatible poly(dimethylsiloxane) (PDMS) and poly(propylene glycol) (PPG). The dynamic dissociation and recombination of hydrogen bonds, coupled with the forced compatibility and spontaneous separation of bi-incompatible soft segments, can effectively dissipate energy, particularly in the crack region during the stretching process. The obtained silicone-based elastomer exhibits a high break strength of 8.0 MPa, good elongation at break of 1910%, ultrahigh toughness of 67.8 MJ m-3, and unprecedented fracture energy of 31.8 kJ m-2 while maintaining their thermal stability, hydrophobicity, healability, and recyclability. This resilient and long-lasting silicone-based elastomer exhibits significant potential for use in flexible electronic devices.

Three-Dimensional Polar Perovskites for Highly Sensitive Self-Driven X-Ray Detection.

Three-dimensional (3D) organic-inorganic hybrid perovskites (OIHPs) have achieved tremendous success in direct X-ray detection due to their high absorption coefficient and excellent carrier transport. However, owing to the centrosymmetry of classic 3D structures, these reported X-ray detectors mostly require external electrical fields to run, resulting in bulky overall circuitry, high energy consumption, and operational instability. Herein, we first report the unprecedented radiation photovoltage in 3D OIHP for efficient self-driven X-ray detection. Specifically, the 3D polar OIHP MhyPbBr3 (1, Mhy=methylhydrazine) shows an intrinsic radiation photovoltage (0.47 V) and large mobility-lifetime product (1.1×10-3  cm2 V-1 ) under X-ray irradiation. Strikingly, these excellent physical characteristics endow 1 with sensitive self-driven X-ray detection performance, showing a considerable sensitivity of 220 µC Gy-1 cm-2 , which surpasses those of most self-driven X-ray detectors. This work first explores highly sensitive self-driven X-ray detection in 3D polar OIHPs, shedding light on future practical applications.

Unprecedented Chiral Three-dimensional Hybrid Organic-Inorganic Perovskitoids.

Chiral three-dimensional hybrid organic-inorganic perovskites (3D HOIPs) would show unique chiroptoelectronic performance due to the combination of chirality and 3D structure. However, the synthesis of 3D chiral HOIPs remains a significant challenge. Herein, we constructed a pair of unprecedented 3D chiral halide perovskitoids (R/S-BPEA)EA6 Pb4 Cl15 (1-R/S) (R/S-BPEA=(R/S)-1-4-Bromophenylethylammonium, EA=ethylammonium), in which the large chiral cations can be contained in the big "hollow" inorganic frameworks induced by mixing cations. Notably, 3D 1-R/S shows natural chiroptical activity, as evidenced by its significant mirror circular dichroism spectra and the ability to distinguish circularly polarized light. Moreover, based on the unique 3D structure, 1-S presents sensitive X-ray detection performance with a low detection limit of 398 nGyair s-1 , which is 14 times lower than the regular medical diagnosis of 5.5 µGyair s-1 . In this work, 3D chiral halide perovskitoids provide a new route to develop chiral material in spintronics and optoelectronics.

[Effectiveness of medial ankle branches propeller "Tennis racket-like" flap in repair of heel-ankle tissue defects].

Objective: To investigate effectiveness of the medial ankle branches propeller "Tennis racket-like" flap in repair of heel-ankle tissue defect. Methods: Between June 2011 and June 2016, 50 patients with heel-ankle tissue defects were treated. There were 40 males and 10 females, with a median age of 35.6 years (range, 6-58 years). The defects were caused by trauma in 44 cases, scar deformity after trauma in 2 cases, chronic ulcer in 2 cases, and squamous cell carcinoma in 2 cases. The defects located at heel in 20 cases, ankle in 15 cases, and heel-ankle in 15 cases. The size of heel-ankle tissue defect ranged from 3.5 cm×2.0 cm to 13.0×10.0 cm. The course of disease ranged from 3 hours to 2 months (mean, 28 days). All wounds were repaired by the medial ankle branches propeller "Tennis racket-like" flap in a size of 3.8 cm×2.2 cm-13.4 cm×10.3 cm. The donor site was directly sutured in 5 cases or repaired by skin grafting in 45 cases. Results: All flaps survived and wounds healed by first intention. Partial necrosis of skin grafting occurred in 1 case, and the wound recovered by change dressing. The other skin grafting survived and wounds healed by first intention. Forty-eight patients were followed up 12 months after operation. The appearance, sensory, and function of repaired heel-ankle flaps were satisfactory. Conclusion: For heel-ankle tissue defect repair, the medial ankle branches propeller "Tennis racket-like" flap has advantages of the high survival rate, reliable blood supply, and sensory recovery.

[Sonographically guided intralesional sclerotherapy for venous malformation].

OBJECTIVE: To investigate the safety and efficacy of sonographically guided percutaneous intralesional sclerotherapy for peripheral venous malformations. METHODS: From March 2004 to October 2007, 32 patients with venous malformations of soft tissues were treated with sonographically guided intralesional sclerotherapy. The malformed venous space was identified intraoperatively by duplex scanning, the gauge 7 needle was inserted into this venous space under real-time ultrasound visualization, and sclerosants were infused in the space gently. Absolute alcohol and bleomycin acted as sclerosants here, combined the two (for type I malformation) or bleomycin only (for type II malformation). The treatment could be repeated if the lesion was not cured in 3 weeks. All patients were followed up for 6 months to 2 years. RESULTS: Of the group, each patient received 1 - 6 times of the therapy (mean, 3 times). Twenty-seven patients achieved a complete response, and 5 achieved partial response. No major complications occurred. CONCLUSIONS: Sonographically guided percutaneous intralesional sclerotherapy for peripheral venous malformation is a simple, effective, safe therapy with minimal invasion, lower morbidity rate, and can be repeated.