Preparation and luminescent properties of CaF2:Ln3+ (Ln:Er,Er/Yb)/Nafion composite films

In this work, CaF_2:Ln~(3+)(Ln:Er,Er/Yb)/Nafion composite films were prepared using Nafion as modifications and matrices by dripping method. The composite films were characterized by Fourier transform infrared spectroscopy(FT-IR), X-ray diffraction(XRD) and scanning electron microscopy(SEM). Composite films are transparent and CaF_2:Ln~(3+)(Ln:Er,Er/Yb) nanoparticles are well dispersed in Nafion films.The thicknesses of CaF_2:Er~(3+)/Nafion and CaF_2:Er~(3+),Yb~(3+)/Nafion composite film are about 77 and 73 μm,respectively. The nanoparticles in composite film possess cubic phase. CaF_2:Er~(3+),Yb~(3+)/Nafion composite film has stronger characteristic emission of Er~(3+) around 1530 nm with full width at half-maximum(FWHM) of 73 nm and longer luminescence lifetimes of 22.04 μs(25.03%) and 100.77 μs(74.97%).     

含齿形裂隙类岩石材料单轴压缩试验研究

为研究含齿形裂隙岩石在单轴压缩下的破坏特征及强度特性，制作了含不同裂隙倾角和起伏角的齿形裂隙类岩石材料试件，并采用岩石力学伺服试验机进行单轴压缩试验。试验结果表明：（1）试件主要产生拉伸、剪切和拉剪复合裂纹，且根据裂纹的扩展路径可划分为A型（拉伸破坏）、B型（剪切破坏）、C型（复合破坏）3种破坏模式，裂隙倾角对试件最终破坏模式影响显著；（2）当裂隙倾角较小时，试件应力—应变曲线为多峰曲线，随着裂隙倾角的增大，曲线呈单峰形式，表现为延性减弱，脆性增强，而裂隙倾角相同但起伏角不同的试件应力—应变曲线大致相同；（3）当裂隙起伏角相同时，试件当量峰值强度随裂隙倾角的增大呈先减小后增大的规律，且裂隙起伏角对试件当量峰值强度的影响小于裂隙倾角。     

Template-assisted spray-drying method for the fabrication of porous particles with tunable structures

Developing strategies for the production of porous particles with controllable structures using a spray-drying method has attracted attention of researchers for decades. Although many papers have reported their successful production of porous particles using this method, information on how to create and control the porous structures as well as what parameters involving and what formation mechanism occurring during the synthesis process are still not clear. To meet these demands, the present review covers strategies in the spray-drying developments for the fabrication of porous particles with controllable structure. This information is important for optimizing the production of porous particles with desirable properties. Regulation of process conditions and precursor formulations are also explained, including composition, type, and physicochemical properties of droplet and raw components used (i.e., host component, template, and solvent). The electrostatic interactions between the individual components and the droplets are also presented, while this information tends to be neglected in the conventional spray-drying process. To clarify how the porous particles are designed, current experimental results completed with illustrations for the proposal particle formation mechanism are presented. The review also completed with the opportunities and potential roles of the changing porous structures in practical uses. This review would provide information on how to produce porous particles that can be used for advanced functional materials, such as catalysts, adsorbents, and sensors.     

Torsional statics of two-dimensionally functionally graded microtubes

A size-dependent governing equation is derived to investigate the torsional static behaviors of two-dimensionally functionally graded microtubes based on the modified couple stress theory. The shear modulus is assumed to vary along the tube’s length direction according to an exponential distribute function, and varies along the tube’s radius direction according to a power-law function. A generalized differential quadrature method is developed to determine the rotational angle and shear stresses. Some illustrative examples are given to investigate the effects of applied torques, the length scale parameter and various material compositions on the torsional angle and shear stresses.     

竹材液化墙体泡沫材料的阻燃改性

为提高竹材液化产物所制备的高轻发泡墙体材料的防火性能，分别采用材料内部添加和表面浸泡的方法进行阻燃改性，并评价不同阻燃剂及其添加量对发泡材料阻燃性能的影响。实验结果表明：在材料内部或表面添加选择的阻燃剂不会对材料自身形貌或组分产生明显影响，对材料的力学性能亦不会造成破坏，在材料内部添加3 g膨胀型凝胶-二氧化硅/聚磷酸铵核壳阻燃剂（MCAPP）后压缩强度达到了0.37 MPa，在材料表面浸泡聚硅氧烷后压缩强度达到了0.58 MPa，同时能提高材料的阻燃性能，在材料内部添加聚磷酸铵（M-APP）后极限氧指数提高到33.2%，比改性前提高3%。在材料表面浸泡膨胀型壳聚糖-蒙脱土-聚磷酸铵（CMAp）后点燃时间明显延长，极限氧指数最高达到了31.5%。     

稀土修饰铁碳材料对糖蜜酒精废水处理效果的研究

采用还原铁粉、碳粉、稀土铈及黏结剂等为原料混合制成的Ce-Fe/C复合材料深度处理糖蜜酒精废水,研究了铁碳质量比、稀土铈添加量以及废水处理时间等因素对处理效果的影响。结果表明:以铁碳质量比为5∶1,稀土铈添加质量分数为7%制备的Ce-Fe/C复合材料处理糖蜜酒精废水,当反应时间为150 min时,色度去除率达98%以上,COD去除率达70%以上。对制备的复合材料的表征结果表明,稀土元素Ce有效地掺杂到Fe/C材料的晶格中,提高了Fe/C材料的性能。     

仿生雾水收集材料：从基础研究到性能提升策略

由于水资源污染、淡水资源日益匮乏，水危机已经严重影响到人们的日常生活。从晨雾中捕获水气则可以缓解干旱地区的缺水问题。受纳米布沙漠甲虫、仙人掌、蜘蛛丝等动植物自发捕集雾水的启发，构建特殊润湿性的仿生雾水收集材料备受关注。详细总结了仿生雾水收集材料的最新研究进展，讨论了仿生集水材料的设计和制备方法，并从雾水收集的四大仿生策略出发，介绍了提升雾水收集效率的设计方案。在此基础上，分析了当前仿生雾水收集过程存在的问题，展望了此类材料未来的发展趋势和方向。     

高性能三水醋酸钠-尿素-膨胀石墨混合相变材料的制备及其在电地暖中的应用性能

采用尿素调节三水醋酸钠的相变温度到合适范围再添加膨胀石墨来降低过冷度，研制了高性能的三水醋酸钠-尿素-膨胀石墨混合相变材料，并对其在电地暖中的应用性能进行了研究。结果表明，当尿素质量分数为36.5%、膨胀石墨添加量为4%(质量)时，所得混合相变材料的熔化焓高达209.1 J/g，熔点在31.98℃，过冷度仅为2.04℃，热导率为2.349 W/(m·K)，热可靠性良好；将用该混合相变材料制成的相变板安装在实验房的电地暖中时，实验房的热舒适度随着相变材料层厚度的增加而增加，但也带来加热时间和用电量的增加；当相变材料层厚度为10 mm时，电加热温度适宜设置在45℃；在热舒适度相当的条件下，有相变板的实验房与无相变板的参比房相比具有用电量小及电费低的优势。     

Formation mechanism of Ti(C,N) solid solution in Al-brown fused alumina refractory at 1973 K in flowing N2

Brown fused alumina is a cost-effective alumina material, and the state of Ti in alumina has a great influence on its high-temperature performance. In this paper, the Ti-containing phases in brown fused alumina particles and Al-brown fused alumina refractory were successfully transformed into Ti(C,N) at 1973 K in flowing N₂. The evolution of the Ti-containing phases in brown fused alumina under high temperature and nitrogen conditions was investigated by XRD, SEM and EDS. The results show that the Ti-containing phases in brown fused alumina include Ti₂O₃, Ti(C,N,O), TiFeSi₂, Ca_0·95Mg_0·9Al_10·1(Ti)O₁₇ and a low-melting point Ca₃Al₂Si₃(Mg,Ti)O₁₂ phase. Under high temperature and nitrogen conditions, the TiO_2[liquid], MgO_[liquid] and SiO_2[liquid] in the low-melting point phase are transformed into Ti(C,N), Mg(g) and SiO(g), while they are supplemented from Ti₂O₃, Ti(C,N,O) and Ca_0·95Mg_0·9Al_10·1(Ti)O₁₇. After heat treatment at 1973 K for 3 h, Ti₂O₃ and Ti(C,N,O) disappear, Ca_0·95Mg_0·9Al_10·1(Ti)O₁₇ is transformed into plate-like Ca_0·55Al₁₁O_17.05, and Ti(C,N) is formed on the surface of the corundum particles. The formation of Ti(C,N) reduces the porosity of the brown fused alumina particles and increases their strength.     

基于临界钙矾石膨胀破坏的磷石膏基复合胶凝材料的配料计算研究

为制备大掺量磷石膏基复合胶凝材料,在确定主要水化产物类型的基础上,通过计算临界钙矾石膨胀破坏的边界条件,确定各组分最佳掺量范围,研究其对复合胶凝材料力学性能、干缩性能的影响,并通过X射线衍射（XRD）、扫描电镜（SEM）等测试方法研究水化产物的组成及发展规律。研究结果表明：通过理论配料计算,矿粉掺量为50%（质量分数）时,最大磷石膏掺量为26.3%（质量分数）,最小熟料掺量为23.6%（质量分数）。最佳配比组28 d胶砂抗压强度为45.2 MPa,线膨胀率小于0.04%;对比组28 d抗压强度仅有36.4 MPa,线膨胀率远大于0.04%。XRD、SEM表征结果表明,磷石膏基复合胶凝材料的水化产物主要是钙矾石（AFt）和水化硅酸钙（C-S-H）凝胶,氢氧化钙几乎反应完全;对比组钙矾石生成量远大于最佳配料组,微观结构存在大量裂缝。这说明理论配料计算可以有效用于磷石膏基复合胶凝材料的配比优化。