Semi-automatic proximal humeral trabecular bone density assessment tool: technique application and clinical validation.

PURPOSE: This study aimed to apply a newly developed semi-automatic phantom-less QCT (PL-QCT) to measure proximal humerus trabecular bone density based on chest CT and verify its accuracy and precision. METHODS: Subcutaneous fat of the shoulder joint and trapezius muscle were used as calibration references for PL-QCT BMD measurement. A self-developed algorithm based on a convolution map was utilized in PL-QCT for semi-automatic BMD measurements. CT values of ROIs used in PL-QCT measurements were directly used for phantom-based quantitative computed tomography (PB-QCT) BMD assessment. The study included 376 proximal humerus for comparison between PB-QCT and PL-QCT. Two sports medicine doctors measured the proximal humerus with PB-QCT and PL-QCT without knowing each other's results. Among them, 100 proximal humerus were included in the inter-operative and intra-operative BMD measurements for evaluating the repeatability and reproducibility of PL-QCT and PB-QCT. RESULTS: A total of 188 patients with 376 shoulders were involved in this study. The consistency analysis indicated that the average bias between proximal humerus BMDs measured by PB-QCT and PL-QCT was 1.0 mg/cc (agreement range - 9.4 to 11.4; P > 0.05, no significant difference). Regression analysis between PB-QCT and PL-QCT indicated a good correlation (R-square is 0.9723). Short-term repeatability and reproducibility of proximal humerus BMDs measured by PB-QCT (CV: 5.10% and 3.41%) were slightly better than those of PL-QCT (CV: 6.17% and 5.64%). CONCLUSIONS: We evaluated the bone quality of the proximal humeral using chest CT through the semi-automatic PL-QCT system for the first time. Comparison between it and PB-QCT indicated that it could be a reliable shoulder BMD assessment tool with acceptable accuracy and precision. This study developed and verify a semi-automatic PL-QCT for assessment of proximal humeral bone density based on CT to assist in the assessment of proximal humeral osteoporosis and development of individualized treatment plans for shoulders.

Neighboring Molecular Engineering in Diels-Alder Chemistry Enabling Easily Recyclable Carbon Fiber Reinforced Composites.

Although a variety of dynamic covalent bonds have been successfully used in the development of diverse sustainable thermosetting polymers and their composites, solving the trade-off between recovery efficiency and comprehensive properties is still a major challenge. Herein, a "one-stone-two-birds" strategy of lower rotational energy barrier (Er ) phosphate-derived Diels-Alder (DA) cycloadditions was proposed for easily recyclable carbon fiber (CF)-reinforced epoxy resins (EPs) composites. In such a strategy, the phosphate spacer with lower Er accelerated the segmental mobility and dynamic DA exchange reaction for network rearrangement to achieve high-efficiency repairing, reprocessing of the EPs matrix and its composites and rapid nondestructive recycling of CF; meanwhile, incorporating phosphorus-based units especially reduced their fire hazards. The resulting materials simultaneously showed excellent thermal/mechanical properties, superb fire safety and facile recyclability, realizing the concept of recycling for high-performance thermosetting polymers and composites. This strategy is of great significance for understanding and enriching the molecular connotation of DA chemistry, making it potentially applicable to the design and development of a wide range of dynamic covalent adaptable materials toward practical cutting-edge-tech applications.

Highly Flame-Retardant and Low Heat/Smoke-Release Wood Materials: Fabrication and Properties.

Wood is an important renewable material exhibiting excellent physical and mechanical properties, environmental friendliness, and sustainability, and has been widely applied in daily life. However, its inherent flammability and susceptibility to fungal attack greatly limit its application in many areas. Use of fire-retardant coatings and preservatives has endowed wood with improved safety performance; importantly, the cooperative effect of dual treatments on the burning behavior and flame retardancy of wood needs to be better understood. Here, a two-step treatment for wood is proposed, with a copper-boron preservative (CBP) and a fire-retardant coating. The thermal degradation and burning behavior of treated wood were investigated. The CBP formed a physical barrier on the wood surface, facilitating a charring process at high temperatures and thus suppressing the release of heat and smoke. Notably, the dual-treated wood exhibited lower heat release and reduced smoke emission compared with the mono-treated wood, indicating a cooperative effect between CBP and fire-retardant coatings, beneficial to the improvement of fire safety. This experimental work improved fire retardance and suppressed smoke release in flammable materials, and offers a new design for developing fire-retardant coatings.

[Application of percutaneous pie-crusting deep medial collateral ligament release for posterior horn surgery of medial meniscus].

OBJECTIVE: To explore clinical and radiographic effects of percutaneous pie-crusting deep medial collateral ligament release in patients with posterior horn tear of medial meniscus combined with tight medial compartment. METHODS: From January 2012 to December 2016, 35 patients with medial meniscus posterior horn injury were treated with percutaneous pie crusting deep medial collateral ligament release technique, including 21 males and 14 females, aged from 21 to 55 years old with an average of (39.1±6.5) years old. Degree of meniscus extrusion were recorded before and 24 months after operation. The knee valgus stress test was performed to evaluate stability of medial collateral ligament, and compared difference between healthy and affected side. Lysholm and IKDC functional scores were compared before and 24 months after operation. RESULTS: All patients were followed up from 27 to 60 months with an average of (36.7±6.8) months. All patients were underwent operation, the wound healed well without complications. Operative time ranged from 0.5 to 1.2 h with an average of (0.8±0.4) h. Nineteen patients were performed partial meniscectomy, 16 patients were performed repair suture. Convex of meniscus before operation was (1.5±0.7) mm, and (1.7±0.4) mm after operation;had no statistical difference(P>0.05). Lysholm score was improved from 53.4±8.8 before operation to 91.5±4.6 at 24 months after operation;IKDC score was increased from 50.7±9.2 before operation to 90.6±3.9 at 24 months after operation;there was statistically significant (P<0.05). Valgus stress test was performed on 0 ° and 30 ° position of knee flexion in affected side and compared with ipsilateral side, all patients showed negative. CONCLUSION: For patients with medial meniscus tear of posterior horn combined with tight medial compartment, percutaneous pie-crusting deep medial collateralligament release could improve medial compartment space, and Knee valgus instability and meniscus extrusion are not affected.

In situ phthalocyanine synthesis chemistry in flames towards molecular fireproof engineering.

The boundaries between phthalocyanine synthesis and combustion chemistry were broken through to achieve molecular fireproofing via in situ phthalocyanine (Pcs) synthesis during combustion. Furthermore in situ Pcs chemistry achieves a flame-retarding organic thermoplastic polymer, showing state-of-the-art fire-safety performance and an ultra-low fire hazard.

Fire hazards management for polymeric materials via synergy effects of pyrolysates-fixation and aromatized-charring.

Previous approaches to suppressing fire hazards are concentrated on brominated flame retardants (BFRs) or phosphorus flame retardants (PFRs). However, their chemical hazards to health and environment have not been able to be ignored currently. It is quite urgent to propose a durable and environmentally-friendly fire-safe strategy, which can eliminate migration, release, and environmental hazards of traditional flame retardants during their use, disposal, and recycling. Herein, we design a fire-responsive molecule (FRM) only containing C, H, and O elements based on full-life-cycle consideration and achieve fire safety via the synergy of specifically binding aliphatic fragments and aromatized charring in combustion. The resulting polymer shows low fire hazard with excellent self-extinguish, low organic volatiles/heat/smoke release, and good comprehensive performance. This polymer can be fabricated to fibres with potential applications for textiles, and electronics, etc. Therefore, we achieve a durable fire-safe strategy without flame-retardant chemicals hazard. This approach can fundamentally eliminate the potential chemical hazards associated with the introduction of halogen or phosphorus flame retardants and give a new vision about solving the "flame retardant chemical hazard issues" that are debated, tracked, and evaluated for several decades.

Fire-Safe Polyesters Enabled by End-Group Capturing Chemistry.

Upon heating, polyesters decompose to small molecules and release flammable volatiles and toxic gases, primarily through chain scission of their ester linkages, and therefore exhibit poor fire-safety properties, thus restricting their applications. Reported herein is an end-group-capturing effect of (bis)oxazoline groups, generated from the thermal rearrangement of the N-(2-hydroxyphenyl)phthalimide (HPI) moiety which was incorporated into the polyester chain by copolymerization. These copolyesters, as a result, exhibit high efficiency in retarding decomposition by capturing the decomposed products, particularly for the carbonyl-terminated fragments, thus increasing the fire-safety properties, such as self-extinguishing, anti-dripping, and inhibiting heat release and smoke production. The successful application of this method in both semi-aromatic and aliphatic polyesters provide promising perspectives to designing versatile fire-safe polymers.