The Reaction Mechanism between MgO and Microsilica at Room Temperature

It was proved that MgO and MicroSilica can react at room temperature, giving a hardened product primarily comprised of Mg （ OH ）2 and Magnesium Silicate Hydrate （ M- S- H ）. The reaction ratio and process and the chemical composion of M- S- H were studied and analyzed by QXRD and DTA- TG. The experimental results indicate that much Mg（ OH）2 and less M-S-H were formed at early period. After 7 days there is no change in the quantity of Mg（ OH）2, while M-S-H was increased slowly. The chemical composion of M-S-H would vary with the mix proportion in the hydrution process , but M1.32 SH2.37 is finally the approximute form.     

Preparation of MgO films as buffer layers by laser-ablation at various substrate temperatures

MgO thin films were deposited on Si(100) substrates by laser ablation under various substrate temperatures (Tsub),expecting to provide a candidate buffer layer for the textured growth of functional perovskite oxide films on Si substrates.The effect of Tsub on the preferred orientation,crystallinity and surface morphology of the films was investigated.MgO films in single-phase were obtained at 473-973 K.With increasing Tsub,the preferred orientation of the films changed from (200) to (111).The crystallinity and surface morphology was different too,depending on Tsub.At Tsub=673 K,the MgO film became uniform and smooth,exhibiting high crystallinity and a dense texture.     

常温下MgO-SiO2-H2O体系胶凝性的研究

利用XRD、DTA、SEM／EDS、IR和MIP以及化学分析等方法研究常温下MgO-SiO2-H2O体系的胶凝性能。结果表明。添加合适的外加组分，常温下MgO-SiO2-H2O体系具有比较优异的胶凝性能，其水化产物主要是非晶态的水化硅酸镁和Mg（OH）2；3d前生成大量的Mg（OH）2和少量的水化硅酸镁，其后水化硅酸镁的量逐渐增多，为硬化浆体提供主要的强度来源。     

热历史对CaO(MgO)-Al_2O_3-SiO_2系统晶化性能和硬度的影响

研究了热历史对一种CaO（MgO）－Al2O3－SiO2系统微晶玻璃的晶化性能和压痕硬度的影响。利用X射线衍射分析了微晶玻璃的晶相种类;结合光学显微镜观察,探讨了热处理温度对晶相体积百分数的影响;确定了硬度与测试荷载之间的关系。实验结果表明,随着热处理的提高,微晶玻璃的晶相含量增加,微晶玻璃的硬度增大     

Synthesis,characterization of monodispersed MgO microspheres and thermal decomposition kinetics of its precusor

Monodispersed MgO microspheres were successfully synthesized by a simple solvothermal method using PEG-400 as solvent. The samples were characterized by X-ray diffraction（XRD） and scanning electron microscopy（SEM）. The results reveal that the precusor was monoclinic Mg5（CO3）4（OH）2·4H2O and composed of nanosheets with the thickness of about 250 nm. By calcining the precusor at 500 °C for 5 min, cubic MgO with similar morphology was obtained. According to the SEM images, it is found that the volume ratio of PEG-400 to deionized water is considered as a crucial factor in the evolution of the morphology. Based on the SEM images obtained under different experimental conditions, a possible growth mechanism which involves self-assembly process was proposed. The thermal decomposition process of MgO precusor was studied by thermogravimetry-differential thermogravimetry（TG-DTG） at different heating rates in air. Thermal analysis kinetics results show that the most probale mechanism models of MgO precusor are An and D3, respectively. In addition, isothermal prediction was studied to quantitatively characterize the thermal decomposition process.     

Tensile and compression properties of Zr-based bulk amorphous alloy at different temperatures

Since the discovery of the Au-Si metallic amorphous alloy ribbon in 1960 by Duwez and co-workers[1] by rapid quenching, rapid developments have been obtained on the preparation of the amorphous alloy with the rapid quenching technique. However, from 1960 to 1989, the amorphous alloy could be only produced into forms of ribbon, flake, wire and powder due to the limitation of the cooling rate (>105 K/s). In the late 1980s, the Inoue group at Tohoku University in Sendai, Japan, investigated th…     

Square concrete columns strengthened with carbon fiber reinforced plastics sheets at low temperatures

Twenty-one square concrete columns were constructed and tested. The testing results indicate that bonded carbon fiber reinforced plastics (CFRP) sheets can be used to increase the strength and improve the serviceability of damaged concrete columns at low temperatures. The failure of the specimens, in most cases, takes place within the middle half of the columns. And the failure of strengthened columns is sudden and explosive. The CFRP sheets increase both the axial load capacity and the ultimate concrete compressive strain of the columns. The ultimate loads of strengthened columns at −10, 0 and 10 °C increase averagely by 9.09%, 6.63% and 17.83%, respectively, as compared with those of the control specimens. The axial compressive strength of strengthened columns is related to the curing temperatures. The improvement of axial compressive strength decreases with reducing temperature, and when the temperature drops to a certain value, the improvement increases with falling temperature.     

Fracture toughness and fracture behavior of SA508-III steel at different temperatures

The fracture toughness of SA508-III steel was studied in the temperature range from room temperature to 320°C using the J-integral method. The fracture behavior of the steel was also investigated. It w...     

亚硫酸氢镁漂白苇浆中高浓打浆试验研究

试验比较亚硫酸氢镁漂白苇浆中浓（12%）和高浓（20%）打浆对浆料纤维形态、光学性能和物理性能的影响.结果表明：在纤维形态方面,高浓打浆较中浓打浆在纤维重均长度、纤维宽度、粗度和细小纤维的含量等方面都要大;在光学性能方面,随着打浆的进行,纸张白度、不透明度及光散射系数等光学性能都有一定程度的下降,高浓和中浓打浆并无明显区别;在物理性能方面,高浓打浆的抗张指数和撕裂指数比中浓打浆要大.     

"C+RE"双重变质对AZ31变形镁合金显微组织和性能的影响

研究了“C＋RE”双重变质处理对AZ31变形镁合金显微组织和力学性能的影响。当对合金进行Ce（“C＋RE”）变质后,合金中出现Al4Ce相,不但细化了基体晶粒,合金中的Mg17Al12也同时细化,从而合金的屈服强度、塑性、冲击韧性得到提高。随着合金中Ce含量的增加合金中的Al4Ce含量也增加,合金的屈服强度、冲击韧性提高但塑性有所下降。     

Simulation and verification of machining deformation for composite materials

Prepreg properties including cure kinetics, cure shrinkage, and coefficient of thermal expansion were analyzed. A simulation method based on ＂element birth and death＂ method of Finite element analysis （FEA） was presented to simulate the cutting process and predict the machining deformation for composite laminates and stiffened panels. The comparisons between the simulation results and experimental data showed good agreement. It is found that residual stresses are the main source of machining deformation for composites and machining deformation is expected to happen only if there are stress gradients along the machining direction. There is no machining deformation for composite laminates due to its uniform stresses distribution in plane, while machining deformation can be observed obviously for T-shape stiffened composite panels. Attention should be paid to machining deformation to avoid the mismatch during assembly.     

铜的高灵敏显色反应及其在生物样品中的应用

研究了Cu(Ⅱ)-4-(2-吡啶偶氮)-间苯二酚-OP高灵敏显色反应,结果表明,在pH=5.6的HAc-NaAc缓冲溶液中,有非离子表面活性剂OP存在时,Cu(Ⅱ)与4-(2-吡啶偶氮)-间苯二酚形成的有色络合物最大吸收波长位于512 nm处,表观摩尔吸光系数达7.27×104L/(mol.cm),铜含量在0~30μg/25mL范围内服从比尔定律,络合物组成比为c(Cu(Ⅱ))∶c(PAR)=1∶2.加入抗坏血酸和柠檬酸盐等可消除Fe3 、Co2 、Ni2 等离子的影响.该方法应用于食品、茶叶中微量铜的测定,相对标准偏差小于7%,回收率在96.8%~106%.     

Performance of MODIS aerosol products at various timescales and in different pollution conditions over eastern Asia

High-quality aerosol optical depth(AOD) data derived from MODIS is widely used in studying spatiotemporal trends of fine particulate matter(PM_(2.5)) concentrations in eastern Asia. However, the differences of MODIS-AOD(3/10 km DT; 10 km DB)under four pollution situations(No-Po; Sl-Po; Mo-Po; Se-Po) are rarely considered. In this study, the MODIS-AOD and AODDifference spatial distributions from 2008 to 2017 are analyzed through annual/seasonal mean AOD maps generated at 0.1°×0.1° resolution. The MODIS-AOD performances are validated using AERONET AOD data for various pollution situations and aerosol types. Annual validations indicate that the 10-km DB algorithm provides the best performance, followed by 3-km DTand 10 km DT. The DB algorithm can provide spatially continuous AOD data for all seasons, whereas the DT algorithm often fails to yield valid data during winter. The validations under different pollution conditions illustrate that severe pollution significantly affects the validity of data obtained by the DB algorithm. However, the accuracy of DT-derived AOD data is robust against interference. Under the same pollution conditions, the correlation coefficient of the DB algorithm is smaller than that of the DT algorithm. The quantity of valid data in the DB product is higher than those in DT products for all pollution conditions, especially under Se-Po.     

在埋地状态下硬聚氯乙烯(UPVC)管变形及土体反作用模数实验研究

UPVC给水管道的承载能力取决于管材的径向变形程度,这种变形又受到周围被动土压力的限制,而与土体种类、密实性等因素有关.本实验研究了埋地状态下UPVC管道空管时的变形情况及其反映多因素参数—土体反作用模数E",得到了合理的设计取值.     

单质合成碘化亚铜及其催化性能研究

在40℃条件下,以铜粉为还原剂、碘单质为氧化剂、乙二醇为溶剂,进行单质之间的反应,制备了碘化亚铜。利用XRD和SEM对产物进行了表征,并对合成的碘化亚铜进行了催化分解高氯酸铵反应的研究,探讨了其催化性能。实验结果表明,碘化亚铜为片状结构,反应温度为40℃的产物粒径为99nm;反应温度为60℃的产物粒径为87nm。碘化亚铜的加入降低了高氯酸铵的低温、高温的分解温度,使得这两部分的分解温度合二为一,高温分解温度提前了111℃。     

低温低浓度下城市污水活性污泥自然培养和驯化

介绍了交互式物化／生化反应器处理城市污水的工艺流程和特点。研究了交互式物化／生化反应器中试系统在低温低进水浓度(水温13-17℃，平均CODcr为144mg／L)自然不接种的情况下，利用生态絮凝剂聚硅硫酸铁和助凝剂聚丙烯酸进行活性污泥培养和成长的过程规律，并在自然状态下(水温17～23℃，平均CODcr为117mg／L)对生成的活性污泥进行驯化。     

结构模型修正中不同残差及权重系数研究

研究了基于改进遗传算法对结构模型修正中用于构建目标函数的不同残差的优缺点和单目标函数中的权重系数。目前工程实践中进行有限元模型修正较多地采用三种残差,包括频率、振型和柔度,本文分析了这三种残差用于模型修正的优缺点,采用改进的遗传算法、利用一个模拟刚度减少的简支梁的仿真模型,对基于不同残差的模型修正进行了比较研究。频率是系统的主要特征参数且识别精度高,修正应优先采用。当修正参数较多,需要补充信息且振型识别误差较小时,可考虑补充振型信息。最后通过对用于构建单目标函数的不同残差采用不同权重系数的比较分析,可以看出当频率残差采用较大权重时的模型修正效果较好。     

不对称变色酸双偶氮试剂-铂系元素-氧化剂三元体系光度分析的研究及应用

报告了３组（胂类、膦类和羧酸类）共８种不对称变色酸双偶氮试剂与某些氧化剂（ＫＩＯ４、ＫＢｒＯ３）之间的褪色反应对于痕量铂系元素的依赖关系。考察了１８个褪色反应的最佳条件、检出限及线性关系范围。提出了一系列光度法测定痕量钌、铑、锇、铱、铂的新方法。此类方法可直接在水溶液中进行、简便快捷，且灵敏度极高。已用于贵金属精矿、催化剂等样品中铂系元素含量的测定。     

水溶液中Fe_2(SO_4)_3与KI反应的研究

研究了不同温度下水溶液中Fe2（SO4）3与KI（Na2S2O3,淀粉）的反应速率．在15－29℃范围内,Fe2（SO4）3与KI（Na2S2O3,淀粉）的反应速率比相同条件下的Fe（NO3）3反应体系慢3-4倍．使用721-分光光度计测定了水溶液中Fe（Ⅲ）与SO42-离子形成配合物的配位比．结果表明,在PH=1．5及21℃时,存在Fe2（SO4）3的二聚体Fe4（SO4）6。