基于功能性橡胶颗粒集成的宽温域橡胶阻尼材料

通过在橡胶基体中集成多种功能性橡胶颗粒(FRGs),构筑具有多相网络结构的阻尼橡胶材料.首先通过扫描电子显微镜(scanning electron microscopy,SEM)和原子力显微镜(atomic force microscopy,AFM)观察所制备集成材料的微观形貌,然后探究了FRGs多种组合对橡胶样品的动态性能的影响.结果表明,基于FRGs集成的多组分样品呈典型的“海-岛”多相结构,在保持每种FRGs组分相对独立的黏弹特性的同时,通过有效的界面反应实现黏弹特性的集成.进一步地,通过调控FRGs的网络结构参数和相对含量实现了各组分损耗峰的有序组合,获得一种多相结构的宽温域阻尼橡胶材料,其在吸音降噪方面展现出较好的应用潜力.此外,该多相阻尼材料还兼具优异的力学性能和吸能减震能力.本文工作基于传统橡胶工业原料和共混工艺,提出了一种简单易行、可规模化生产的橡胶阻尼材料制备新策略,不涉及复杂合成与改性,为发展高性能橡胶阻尼材料提供了新思路.

Clinical efficacy of the modified Helicobacter pylori eradication therapy for Helicobacter pylori-negative gastric mucosa-associated lymphoid tissue lymphoma:a meta analysis

Background::Helicobacter pylori(HP)has been considered to be one of the primary causes of gastric mucosa-associated lymphoid tissue(MALT)lymphoma since 1993.Low-grade gastric MALT lymphoma with HP is widely treated with HP eradication therapy,according to each specific clinical situation.However,several studies and guidelines indicate that the modified HP eradication therapy is also valid for HP-negative gastric MALT lymphoma.The aim of this study was to perform a meta-analysis of the clinical efficacy of the modified HP eradication therapy for gastric MALT lymphoma without HP.Methods::We searched studies that reported the response rate of the modified HP eradication therapy regimen for gastric MALT lymphoma without HP by using PubMed,Medline,and Ebsco from January 1971 until February 2019.All statistical analyses were carried out using R 3.5.3(Mathsoft Company,Cambridge,MA,USA).The pooled response rate was expressed as a decimal.The heterogeneity test was performed using the I-squared(I2)statistic.Results::A total of 14 studies were selected with a total of 148 patients with HP-negative gastric MALT lymphoma.The overall pooled response rate was 0.38(95%confidence interval[CI]:0.29-0.47).The combined estimate is I2=57%(P<0.01).The study subjects were categorized by factors(area of patients).The pooled response rate of the sub-groups(Korea,Japan,China,and Western countries)was 0.63(95%CI:0.50-0.76),0.16(95%CI:0.05-0.30),0.38(95%CI:0.20-0.55),and 0.57(95%CI:0.08-1.00).The response rate showed that the modified HP eradication therapy was effective for patients with HP-negative gastric MALT lymphoma,especially in Korea and Western countries.Conclusion::Therefore,the modified HP eradication therapy can be considered an optional therapy for patients with low-grade HP-negative gastric MALT lymphoma.However,several limitations were revealed in the meta-analysis.Further systematic reviews and research are required.

Structural Manipulation of Aminal-crosslinked Polybutadiene for Recyclable and Healable Elastomers

Recently,increasingly growing efforts have been devoted to incorporating dynamic covalent bonds into covalently crosslinked networks to address the persistent trade-offs between chemical crosslinking and malleability.Herein,a series of dynamic aminal bond crosslinked polybutadiene rubbers(PAPB)are prepared by crosslinking aldehyde group-terminated polybutadiene rubber(APB)with piperazine.By varying the molecular weight of APB,the crosslinking density of PAPB is changed,which offers the platform to regulate the mechanical characteristics and dynamic properties.Specially,with the decrease of APB molecular weight,i.e.with the increase of crosslinking density,the modulus of PAPB gradually increases while the elongation at break conversely decreases,and the activation energy for network rearrangement initially decreases and then increases.The resultant PAPB exhibit vitrimer-like behaviors that can alter the network topologies at elevated temperatures without the loss of structural integrity through dissociative aminal exchange reactions,while the protic source can accelerate aminal dissociation and result in network dissolution even at room temperature.Due to the aminal exchange,PAPB are thermally malleable and can almost restore the original mechanical characteristics after recycling;besides,they are capable of healing at a relatively low crosslinking density.