Natural Polysaccharides as Multifunctional Components for One-Step 3D Printing Tough Hydrogels

Natural polysaccharides (NPS) are regarded as biomolecular and structural components for preparing high-performance tough hydrogels. But the one-step fabrication of NPS-containing hydrogels in seconds and the template-free design of complicated high-resolution structures are still significant challenges in this field. To meet these requirements, various NPS-containing tough hydrogels are fabricated and processed into 2D/3D structures via the combination of Ru(bpy)₃²⁺-mediated photochemistry and extrusion 3D printing technique. The whole fabrication process is one-step, completed in tens of seconds under visible light irradiation. It is found that the used NPS plays a key role in achieving the fabrication of high-performance structured tough hydrogels. The high reactivity of functional groups in the used NPS can shorten their gelation times. Long rigid chains of the used NPS, their hierarchical assemblies, and contrasting multinetworks benefit from the efficient dissipation of mechanical energy and enhancement of its operational stability. Strong supramolecular interactions enable hydrogel precursors to have high viscosities, therefore providing good controllability to design high-resolution and complicated tough hydrogel structures via extrusion 3D printing. It is anticipated that this straightforward fabrication strategy and findings will open new horizons for NPS-containing materials.     

Tough Transient Ionic Junctions Printed with Ionic Microgels

Emerging soft ionotronics better match the human body mechanically and electrically compared to conventional rigid electronics. They hold great potential for human-machine interfaces, wearable and implantable devices, and soft machines. Among various ionotronic devices, ionic junctions play critical roles in rectifying currents as electrical p–n junctions. Existing ionic junctions, however, are limited in electrical and mechanical performance, and are difficult to fabricate and degrade. Herein, the design, fabrication, and characterization of tough transient ionic junctions fabricated via 3D ionic microgel printing is reported. The 3D printing method demonstrates excellent printability and allows one to fabricate ionic junctions of various configurations with high fidelity. By combining ionic microgels, degradable networks, and highly charged biopolymers, the ionic junctions feature high stretchability (stretch limit 27), high fracture energy (>1000 Jm⁻²), excellent electrical performance (current rectification ratio >100), and transient stability (degrade in 1 week). A variety of ionotronic devices, including ionic diodes, ionic bipolar junction transistors, ionic full-wave rectifiers, and ionic touchpads are further demonstrated. This study merges ionotronics, 3D printing, and degradable hydrogels, and will motivate the future development of high-performance transient ionotronics.     

急倾斜煤层群坚硬顶板导爆索爆破放顶试验

淮南孔集煤矿在有煤尘爆炸危险及项板坚硬的采空区内进行中深孔挤压爆破时，在国内率先应用煤矿安全导爆索代替多雷管起爆，成功地进行了22次爆破，解决了生产急需，获得了较好的技术经济效果．并在导爆索起爆性能测定、操作工艺及在有煤尘爆炸危险的采空区内如何安全爆破等方面取得了经验．     

环氧丙烯酸/聚氨酯丙烯酸酯共混体系的紫外光固化及力学性能的研究

采用紫外光固化的不同类型聚氨酯丙烯酸酯对环氧丙烯酸酯进行了增韧改性。利用索氏提取法研究了共混体系的紫外光固化行为。DSC和TGA对共混体系的热学性能研究表明：共混体系的相容性良好，且热分解温度比纯环氧丙烯酸酯提高了19℃。测试了共混体系的力学性能并利用SEM对冲击断面形貌进行了观察。找出并初步探讨了聚氨酯丙烯酸酯增韧环氧丙烯酸酯的微观机理。试验表明：当聚氨酯丙烯酸酯用量为3．6％时，体系的冲击性能可提高300％以上。     

半圆形深槽带式输送机的研究

研究半圆形深槽带式输送机可以实现大倾角输送的工作原理 ,并得出了半圆形深槽带式输送机的基本设计原则 ;在理论分析的基础上 ,给出了合理的托辊组布置方案 ;通过半圆形深槽带式输送机与其他形式带式输送机的比较 ,总结了半圆形深槽带式输送机的特点。     

环氧丙烯酸酯增韧间苯二甲酸二烯丙酯树脂体系的聚合反应及断面形态

采用环氧丙烯酸酯 (VE)为间苯二甲酸二烯丙酯 (DAIP)树脂的增韧剂 ,体系的韧性得到改善。利用 DSC、FTIR等方法进一步研究了 DAIP/ VE体系的聚合反应 ,证明改性体系中存在两个反应阶段 ;前一阶段即低温固化阶段 ,主要为 VE与 DAIP的共聚反应以及少量 VE的自聚反应 ;后一阶段即高温固化阶段 ,主要为 DAIP的自聚反应。改性体系与未改性体系相比 ,断面形态结构更为多样。     

超韧尼龙11合金的力学性能和相态研究

研究了尼龙11和POE的共混物，制备了不同的马来酸酐接枝率的尼龙11／POE－g－MAH和尼龙11／POE／POE－g-MAH共混物，研究了共混物的力学性能和相态。结果表明，引入POE－g-MAH能够提高相容性和共混物的韧性，并且马来酸酐接枝率越高效果越为明显，与此同时，拉伸强度却降低得很少。     

热致型液晶增韧热固性树脂的研究进展

由于现有的热固性树脂增韧方法存在种种缺陷，热致型液晶正取代橡胶弹性体、热塑性塑料等成为新一类热固性树脂增韧剂，与其它方法相比，该法增韧效果好，改性体系耐热性、模量高。从液晶聚合物增韧、液晶单体／低聚物增韧、液晶固化剂增韧三个方面综述了现阶段热致型液晶增韧热固性树脂的研究进展。     

The psychology of politics: a reply.

Eysenck's tough-mindedness-tender-mindedness hypothesis is arbitrarily and invalidly criticized by Rokeach and Hanley (see 31: 2846). (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

VE增韧DAIP体系的性能研究

用乙烯基酯树脂(VE)对间苯二甲酸二烯丙酯(DAIP)进行增韧改性,研究了VE种类及用量对改性体系力学性能、耐热性能、电气绝缘性能的影响。改性后体系粘度为0.5Pa.s,成型工艺性好;固化树脂的冲击强度提高了4.2倍,弯曲强度提高了1.2倍,耐热性基本不变,电气绝缘性能随温度变化较小,证明改性体系在韧性提高的同时其它性能没有下降,有的甚至还有提高。