知母多糖复合酶提取工艺优化及其免疫活性

本文对知母多糖的提取工艺及体外免疫活性进行研究,为知母多糖的开发利用提供理论依据。试验以复合酶提取知母粗多糖,在正交试验确定复合酶比例的基础上,通过单因素实验和响应面优化试验,确定知母多糖的最佳提取工艺;采用DEAE-52纤维素层析柱进行分离得到4种多糖组分APSE-0、APSE-1、APSE-2和APSE-3。以RAW264.7巨噬细胞为研究模型,采用MTT法、Griess法测定知母多糖各组分对细胞增殖能力和一氧化氮（NO）释放量的影响。结果表明,最佳复合酶比例为:木瓜蛋白酶16000 U/g,纤维素酶1200 U/g,果胶酶1600 U/g。最优提取工艺为酶解时间2 h,液料比15:1（mL/g）,酶解温度52 ℃,在此条件下得率为（10.58%±0.03%）。体外免疫活性实验结果证明,四种知母多糖组分均能明显促进RAW246.7巨噬细胞的增殖,APSE-0、APSE-2和APSE-3均可极显著诱导NO的释放,其中,APSE-2的免疫活性最强,可作为潜在的功能性食品或作为免疫力低下人群的膳食补充剂。剂。     

Photocatalytic Reduction of Graphene Oxide–TiO2 Nanocomposites for Improving Resistive‐Switching Memory Behaviors

Graphene oxide (GO)‐based resistive‐switching (RS) memories offer the promise of low‐temperature solution‐processability and high mechanical flexibility, making them ideally suited for future flexible electronic devices. The RS of GO can be recognized as electric‐field‐induced connection/disconnection of nanoscale reduced graphene oxide (RGO) conducting filaments (CFs). Instead of operating an electrical FORMING process, which generally results in high randomness of RGO CFs due to current overshoot, a TiO₂‐assisted photocatalytic reduction method is used to generate RGO‐domains locally through controlling the UV irradiation time and TiO₂ concentration. The elimination of the FORMING process successfully suppresses the RGO overgrowth and improved RS memory characteristics are achieved in graphene oxide–TiO₂ (Go‐TiO₂) nanocomposites, including reduced SET voltage, improved switching variability, and increased switching speed. Furthermore, the room‐temperature process of this method is compatible with flexible plastic substrates and the memory cells exhibit excellent flexibility. Experimental results evidence that the combined advantages of reducing the oxygen‐migration barrier and enhancing the local‐electric‐field with RGO‐manipulation are responsible for the improved RS behaviors. These results offer valuable insight into the role of RGO‐domains in GO memory devices, and also, this mild photoreduction method can be extended to the development of carbon‐based flexible electronics.     

油气生产企业重大安全突发事件社会影响扩散模型

油气生产企业发生安全突发事件的频率较高,一般性安全突发事件极易借助一定的条件和动力扩散成为重大安全突发事件,进而造成巨大的经济损失甚至带来更为严重的社会负面影响。为了有效控制突发事件的发生、扩散和衍变,通过分析重大安全突发事件属性及强度、承灾对象脆弱性、应对体系脆弱性这3个扩散影响因素,借助系统分析思想和系统动力学方法构建了社会影响扩散模型来有效控制事件扩散升级;结合油气生产常见突发事件对3个扩散因素进行控制管理分析,建立了影响因素脆弱性指标评价体系,并提出借助层次分析法进行对象脆弱性的定量分析。最后指出:油气生产企业应加强日常管理和监督,降低重大安全突发事件发生的可能性;寻找控制承灾对象和社会应对体系脆弱性的关键因素并进行有效管理,降低事件扩散的速度和可能性。该成果可为安全突发事件的控制、预警机制的构建提供参考。     

不同粒径橡胶集料混凝土工程特性试验

用橡胶颗粒取代砂子,对橡胶集料混凝土进行工作性测定及单轴抗压试验、抗水渗试验、抗氯离子渗透试验、冻融循环试验。结果表明:存在最不利橡胶颗粒粒径0.63～1.25 mm,使混凝土流动性最差;混凝土抗压强度随橡胶颗粒粒径减小而下降,但掺入小粒径橡胶颗粒有助于保证混凝土完整性;存在最优取代粒径0.165～0.315 mm,使混凝土电通量、渗水高度、质量损失率、相对动弹性模量损失率分别为普通混凝土的53.15%、52.35%、16.35%、51.79%;利用耐久性最优配合比制备的橡胶集料钢筋混凝土简支梁起裂荷载高于普通钢筋混凝土简支梁,但极限荷载有所降低,降幅约为6.10%。     

Deep neural networks for rank-consistent ordinal regression based on conditional probabilities

Pattern Analysis and Applications - In recent times, deep neural networks achieved outstanding predictive performance on various classification and pattern recognition tasks. However, many...     

Three‐dimensional Printing for Catalytic Applications: Current Status and Perspectives

Three‐dimensional (3D) printing, also known as additive manufacturing, is a fabrication method that has recently received worldwide attention. It provides a convenient and economical way to prepare 3D structures in designable ways. As the technology has developed and the operational costs have decreased, the applications of 3D printing have greatly expanded. Catalyst fabrication is a promising area for 3D printing. Printing processes result in better control of catalyst structures and catalyst distribution. In this perspective, a general overview of the commonly available 3D printing methods that are feasible for the preparation of heterogeneous catalysts is given. Additionally, recent works on printing strategies and new materials for catalysts are discussed. Future development is also addressed.     

中国2019年黄金物质流分析

党的“十九大”提出中国经济正由高速增长阶段转向高质量发展阶段,这标志着我国黄金行业也必须从过去只重视规模速度的粗放型发展方式向注重质量效益的集约型发展方式转变。为了更好地了解中国黄金行业的发展现状,探究黄金在社会经济系统中的代谢过程,本文运用物质流分析方法,依据文献调研和统计数据,通过搭建黄金物质流框架,以2019年为例探讨我国黄金物质流的实现路径,对物质流中生产、加工制造、使用、废弃物管理4个阶段展开具体分析。研究结果表明：1）生产阶段向加工制造阶段流入精炼金1 015 t,金矿尾渣排放损耗黄金900 t。在此阶段,金矿资源的严重消耗与环境污染加剧问题对我国黄金产业的可持续发展产生了不利影响。2）加工制造阶段的进口纯金量为781 t,向使用阶段流入精炼金1 706 t,黄金损耗为90 t。2019年我国黄金供给对外依存度达到52.5%,显示出整体偏高的态势。3）在使用阶段,2019年我国黄金需求总量为1 641 t,其中黄金消费量为1 003 t,黄金消费以金饰为主,占该年黄金消费量的67.4%。4）在废弃物管理阶段,2019年我国回收黄金量为465 t,占该年黄金供应量的27%。研究结论：1）我国黄金生产以矿产金为主、有色冶炼副产金为辅,其中有色副产金占黄金总产量的比例从2000年的9%增长到2019年的16%,表明我国黄金产业的集约化程度正在逐步提高。2）我国对黄金资源需求量巨大,黄金资源对外依存度较高。近些年我国工业领域的黄金消费量增长很快,未来随着电子产业的快速发展还会不断扩大对黄金资源的需求。3）回收黄金是我国黄金资源供应的重要组成部分,其中黄金饰品的回收收益比工业回收高出很多,工业黄金回收工艺还有待进一步提高,产业链还有待进一步完善。     

Scale-Spanning Strong Adhesion Using Cellulose-Based Microgels

Adhesive gels derived from biobased sustainable materials have extremely broad application prospects, such as in flexible smart materials and biomedicine fields. Combining high toughness and strong, persisting repeatable adhesion has always been a daunting challenge for adhesive gels. However, bulk gels based on polysaccharides as the most abundant bio-based compounds usually possess a high toughness but weak interfacial adhesion due to the strong hydration potential. Herein, a novel kind of highly tough microgel membranes with rough surfaces is fabricated using loosely chemically cross-linked dihydroxypropyl cellulose (cDHPC) microgels (average size = 1.25 ± 0.03 µm). Such microgel membranes exhibit strong, instant, and persisting adhesion to various substrates with different surface roughness. Slight chemical cross-linking and multiple physical interactions within microgels and resulting microgel membranes lead to high tensile strength and toughness of 0.23 ± 0.03 MPa and 73.8 ± 9.3 KJ m⁻³, respectively. The maximum adhesive strength and debonding work exceed 320 ± 0.50 KPa and 160.97 ± 0.20 J m⁻², respectively. After five cycles (re-lap after detaching), the adhesive strength still remains above 200 KPa. Their adhesive properties outperform most bio-based adhesive gels and even petroleum-based gels, which are based on synergistic molecular and microscaled topological interactions.     

基于多目标的小流域污染控制方案及效果——以苏州胥江小流域为例

在太湖流域大网模型基础上,根据设计水文条件、边界水质以及控制断面水质与其上游概化排污口污染源的响应关系,建立胥江小流域污染物限排总量3级串级模型。计算基于多个控制断面在不同水质目标下的流域污染物限排总量。根据流域污染现状及污染物限排总量,提出包括总量控制措施及末端河道微污染水治理措施在内的污染综合控制方案,对综合控制方案水质改善效果进行评估。结果表明：①现状 COD 排放量超出限排总量153％、NH3－N 超出73％、TP 超出236％;②胥江小流域污染综合控制方案实施后,各控制断面水质均能达到目标要求。