Punching shear behavior of recycled aggregate concrete slabs with and without steel fibres

A study on the punching shear behavior of 8 slabs with recycled aggregate concrete (RAC) was carried out. The two main factors considered were the recycled coarse aggregate (RCA) replacement percentage and the steel fibre volumetric ratio. The failure pattern, load-displacement curves, energy consumption, and the punching shear capacity of the slabs were intensively investigated. It was concluded that the punching shear capacity, ductility and energy consumption decreased with the increase of RCA replacement percentage. Research findings indicated that the incorporation of steel fibres could not only improve the energy dissipation capacity and the punching shear capacity of the slab, but also effectively improve the integrity of the slab tension surface and thereby changing the trend from typical punching failure pattern to bending-punching failure pattern. On the basis of the test, the punching shear capacity formula of RAC slabs with and without steel fibres was proposed and discussed.     

粗粒含量对排土场堆石体剪切变形和强度的影响研究

为探讨粗粒含量对堆石体剪切特性的影响, 采用室内中型直剪仪, 对不同组构试样开展了剪切试验。研究表明, 粗粒料剪切过程中没有明显的峰值强度, 且应力应变关系表征为应变硬化型。相同正应力条件下, 试样剪切应变达到1/100时的剪切模量随粗粒含量增加而增大, 试样在破坏时的剪切模量随着粗粒含量增加呈先增大后减小的趋势, 且粗粒含量为70%时试样剪切破坏模量达到最大值。粗粒料内摩擦角与粗粒含量之间存在指数关系, 相关系数为0.912 6, 摩擦角随粗粒含量增加而增大; 粘聚力与粗粒含量间的规律性尚不明显。     

我国混凝土骨料的现状与问题

针对目前我国天然矿石资源短缺、乱采滥挖砂石的现象屡禁不止、砂石质量严重失控的现状,应提高对砂石重要性的认识,引导砂石行业成为保护环境、开发建设用地、充分利用废弃资源的主力军。发展以工业废渣及淤泥、岩石为原料的人造轻骨料,积极开展再生骨料的应用研究工作。     

混杂纤维增强再生砖骨料混凝土增强机制与抗压性能计算方法

通过钢-聚烯烃混杂纤维增强再生砖骨料混凝土（HF/RBAC）的抗压与弹性模量试验,研究了再生砖骨料（RBA）取代率、混杂纤维掺量、纤维种类对混凝土抗压强度和弹性模量的影响。根据RBA的XRD图谱、X-CT图像、RBA火山灰活性成分与水泥水化产物反应原理及能量平衡原理,分析了HF/RBAC的破坏机制和纤维增强机制。研究表明,当RBA全取代天然骨料（NA）时,HF/RBAC立方体抗压强度、轴心抗压强度和弹性模量分别降低了36.72%、24.95%和43.53%。当钢-聚烯烃混杂纤维体积掺量为1.5%时,HF/RBAC立方体抗压强度、轴心抗压强度和弹性模量分别增加了20.51%、30.33%和35.84%。最后,提出了考虑RBA压碎指标和取代率、纤维种类和掺量等因素影响的HF/RBAC抗压强度和弹性模量的计算方法。     

Rigid Schiff Base Complex Supermolecular Aggregates as a High-Performance pH Probe: Study on the Enhancement of the Aggregation-Caused Quenching (ACQ) Effect via the Substitution of Halogen Atoms

Optical signals of pH probes mainly driven from the formation or rupture of covalent bonds, whereas the changes in covalent bonds usually require higher chemical driving forces, resulting in limited sensitivity and reversibility of the probes. The exploration of high-performance pH probes has been a subject of intense investigation. Herein, a new pH probe has been developed, with optical property investigation suggesting the probe has excellent signal-to-noise ratio, and fluorescence intensity shows exponential growth, combined with a visible color change, as pH increased from 5.1 to 6.0; Moreover, the probe has outstanding stability and reversibility, with more than 90% of the initial signal intensity remaining after 30 cycles. In order to better understand the special fluorescence behavior of the reported probe, the non-halogenated isomer is introduced for comparison, combined with the results of structural analysis, quantitative calculation and optical experiments, and the possible mechanism of the special supramolecular aggregation-caused quenching effect induced by the halogen atom is discussed.     

沥青质分子聚集体中π-π相互作用的研究

采用量子力学与分子动力学相结合的方法对形成沥青质分子聚集体的分子间π-π相互作用进行了研究。结果表明：沥青质分子间的π-π相互作用能随着分子芳香环数的增加而增大;分子中含有的杂原子显著增加了沥青质分子间的π-π相互作用能;沥青质分子的支链长度及类型能够影响π-π相互作用能的大小;当沥青质分子聚集体中含有多个π-π相互作用时,其分子间的聚集作用力会大大增加;沥青质分子间形成π-π相互作用的过程中,分子间有少量的电子转移;色散作用是π-π相互作用中的主要作用。     

非设计集合的高速立式数控加工中心立柱的拓扑优化

基于连续体ICM拓扑优化方法,笔者提出了不在体积约束下的多阶频率加权和为目标函数,考虑非设计集合的拓扑优化方法。在CAD/CAE设计系统中,针对高速立式加工中心的动态特点,确定加工中心的关键结构件立柱为优化对象,并考虑其它重要零件影响。根据此方法设计的高速立式加工中心立柱,使得整机动态特性有很大提高。     

水淬铜渣作为混凝土组分的研究

本文从理论和应用两方面就水淬铜渣作为混凝土组分的问题进行了系统的研究。试验发现:水淬铜渣具有微火山灰效应;铜渣混凝土的工作性较差,但掺加适量微集料后会显著改善其工作性;铜渣混凝土在物理力学性能和耐久性能方面与普通混凝土差别不大;铜渣颗粒与水泥石之间粘结良好,铜渣的微火山灰效应能改善界面过渡层。研究表明:水淬铜渣作为混土的组分,不仅具有与普通混凝土相同的物理力学性能和耐久性能,还能取得可观的经济和环境效益。     

基于骨架密实理论的矿料级配设计方法研究

现行的《沥青路面施工技术规范（JTGF40-2004）》中给出的矿料级配范围过宽,给实际工程的配合比设计带来较大困难。以杭州湾大桥南接线路面工程为背景,通过对国内设计方法的研究和室内的对比试验,提出了简便易行的矿料级配设计方法。     

Production of combi-CLEAs of glycosidases utilized for aroma enhancement in wine

Glycosidases are frequently used in winemaking to liberate glycosidically bound aroma compounds. Since most of the glycosidases used for diglycoside hydrolysis act sequentially, their co-immobilization is an attractive alternative from a technical and economical perspective. The enzymes α-l-arabinosidase (ARA) and β-d-glucosidase (βG) from the preparation Rapidase^®AR2000 were co-immobilized in CLEAs (combi-CLEAs), evaluating the effect of bovine serum albumin (BSA) addition and the concentration of glutaraldehyde (Glu) on enzyme immobilization yield and expressed activity. Combi-CLEAs prepared with a Glu to Rapidase protein mass ratio of 0.053 and BSA to Rapidase protein mass ratios of 1, 0.33, and 0.2 were selected, evaluating their stability at simulated winemaking conditions: 25 °C, pH 3.5, and 10% (v/v) of ethanol. All combi-CLEAs were more stable than the soluble enzymes, the best result being obtained at a BSA to Rapidase protein mass ratio of 0.33. Half-lives of βG and ARA in combi-CLEAs were 43.9 and 54.9 days, respectively, whereas in the case of the soluble enzymes were only 1.3 and 6.2 days, respectively. Immobilization yields were 79.1 and 47.1% in terms of βG and ARA activity, respectively. Combi-CLEAs of glycosidases are technologically relevant robust biocatalysts for their application as aroma enhancers in winemaking.