熟化过程中结构与组分的变化对天然橡胶性能的影响

熟化是天然橡胶加工过程中的重要工序之一,过程中往往伴随着天然橡胶的结构与组分变化,从而引起天然橡胶性能的改变。但是,天然橡胶的结构和组分随着熟化的进行而同步发生改变,因此二者各自对天然橡胶性能的影响大小尚不明确。文中采用TSR 10,TSR 10CV和TSR 3CV不同样品来对比分析天然网络和非胶组分各自对NR性能的影响。结果表明,熟化过程中天然网络结构的增加对门尼黏度值和塑性初值的升高有较大的贡献,而非胶组分含量的减少则对其影响较小。对于未填充天然橡胶硫化胶而言,非胶组分的分解是力学性能提高的重要来源;而天然网络结构对有效交联密度和力学性能的贡献具有一定协同效应,但贡献幅度相对有限。对于填充炭黑天然橡胶硫化胶而言,3个样品的常规力学性能无明显差异,但TSR 10的整体动态疲劳性能最优,TSR 10CV其次,TSR 3CV最差。说明非胶组分的降解和天然网络结构的存在均有利于填充炭黑天然橡胶硫化胶动态力学性能的提高。

Reconstructing avascular necrotic femoral head through a bioactiveβ-TCP system:From design to application

A variety of techniques have been used for treating avascular necrosis of the femoral head(ANFH),but have frequently failed.In this study,we proposed aβ-TCP system for the treatment of ANFH by boosting revascularization and bone regeneration.The angio-conductive properties and concurrent osteogenesis of the highly interconnected porousβ-TCP scaffold were revealed and quantified through an in vivo model that simulated the ischemic environment of ANFH.Mechanical test and finite element analysis showed that the mechanical loss caused by tissue necrosis and surgery was immediately partially compensated after implantation,and the strength of the operated femoral head was adaptively increased and eventually returned to normal bone,along with continuous material degradation and bone regeneration.For translational application,we further conducted a multi-center open-label clinical trial to assess the efficacy of theβ-TCP system in treating ANFH.Two hundred fourteen patients with 246 hips were enrolled for evaluation,and 82.1%of the operated hips survived at a 42.79-month median follow-up.The imaging results,hip function,and pain scores were dramatically improved compared to preoperative levels.ARCO stage II disease outperformed stage III in terms of clinical effectiveness.Thus,bio-adaptive reconstruction using theβ-TCP system is a promising hip-preserving strategy for the treatment of ANFH.

Acceptor Engineering Produces Ultrafast Nonradiative Decay in NIR-Ⅱ Aza-BODIPY Nanoparticles for Efficient Osteosarcoma Photothermal Therapy via Concurrent Apoptosis and Pyroptosis

Small-molecule photothermal agents(PTAs)with intense second near-infrared(NIR-Ⅱ,1,000 to 1,700 nm)absorption and high photothermal conversion efficiencies(PCEs)are promising candidates for treating deep-seated tumors such as osteosarcoma.To date,the development of small-molecule NIR-Ⅱ PTAs has largely relied on fabricating donor–acceptor–donor(D–A–D/D′)structures and limited success has been achieved.Herein,through acceptor engineering,a donor–acceptor–acceptor(D–A–A′)-structured NIR-Ⅱ aza-boron-dipyrromethene(aza-BODIPY)PTA(SW8)was readily developed for the 1,064-nm laser-mediated phototheranostic treatment of osteosarcoma.Changing the donor groups to acceptor groups produced remarkable red-shifts of absorption maximums from first near-infrared(NIR-Ⅰ)regions(~808 nm)to NIR-Ⅱ ones(~1,064 nm)for aza-BODIPYs(SW1 to SW8).Furthermore,SW8 self-assembled into nanoparticles(SW8@NPs)with intense NIR-Ⅱ absorption and an ultrahigh PCE(75%,1,064 nm).This ultrahigh PCE primarily originated from an additional nonradiative decay pathway,which showed a 100-fold enhanced decay rate compared to that shown by conventional pathways such as internal conversion and vibrational relaxation.Eventually,SW8@NPs performed highly efficient 1,064-nm laser-mediated NIR-Ⅱ photothermal therapy of osteosarcoma via concurrent apoptosis and pyroptosis.This work not only illustrates a remote approach for treating deep-seated tumors with high spatiotemporal control but also provides a new strategy for building high-performance small-molecule NIR-Ⅱ PTAs.