富磷灰石复杂稀土矿石工艺矿物学研究

通过化学分析、显微镜和国际先进的MLA矿物自动检测技术等手段,对某富磷灰石的复杂稀土矿石进行工艺矿物学研究.研究结果表明,本矿石稀土矿物主要为氟碳铈矿和褐帘石,其次为独居石和氟碳钙铈矿.此外,磷灰石中富含稀土,磷灰石中稀土占原矿总稀土量26％以上.本稀土矿石性质决定仅采用物理选矿方法不能得到商品稀土精矿,可采取浮选流程和浮磁联合流程分别获取磷灰石精矿和稀土精矿,然后再通过焙烧浸出工艺提取稀土.     

基于优势的双边匹配决策方法

传统的双边匹配方法根据主体双方给出的偏好序信息排序, 忽略匹配双方个体间存在的差异, 匹配结果不能很好的满足主体需求, 稳定性较差, 造成资源的错配甚至浪费。本文以人为出发点, 基于对匹配主体特征属性的优势结构识别, 提出新的序值依据, 将定性的不确定匹配标准依重视程度量化, 从而实现对人的多维度测量, 最大化个体差异, 以实现“按需匹配”的高稳定性、高满意度匹配结果。构建基于主体客观评价的优势属性量表; 引入个体综合情况的计算公式; 依托隶属度加权法把多目标优化转变成单目标优化; 运用Hungarain方法获得满意度最高且稳定匹配的指派方案; 最后通过算例证明本方法的科学性和可行性。     

简约SUR模型参数的协方差改进估计

考虑了SUR模型及其两个简约模型,给出简约模型下未知回归系数及其可估函数的协方差改进估计,并证明了在一定条件下该估计仍然是相应参数在原模型下的协方差改进估计.     

MgF2表面结构稳定性及电子特性的密度泛函理论研究

用密度泛函理论(DFT)研究了MgF₂(010)、MgF₂(001)、MgF₂(011)及MgF₂(110)四种表面10种构型的稳定性和电子特性. 结果表明: 四种表面的邻近表面几层原子均出现了明显的驰豫现象, 终止于单层F原子的表面相对稳定; 进一步对比分析四种表面(终止于单层F原子的稳定构型)的表面能发现, 稳定性依次减弱排列为MgF₂(110)、MgF₂(011)、MgF₂(010)、MgF₂(001); 最稳定的MgF₂(110)表面的态密度显示在费米能级以下较多的成键电子处于低能级区, 同时由于表面的影响, 导致表面F原子电荷聚集显负电性, 促使表面活性增加.     

Optical properties and CO_2 laser SHG with HgGa_2S_4

Optical properties and nonlinearity on phase-matching (PM) of two (yellow and orange) phase crystals were investigated in details. Damage threshold was determined in comparison with middle infrared (IR) crystal at identical experimental conditions. Second harmonic generation (SHG) of 30 ns TEA CO2 laser pulses was realized with 5% efficiency in energy and 6.9% in peak power.     

钙钛矿型层状化合物K2Sm2Ti3O10的合成及XRD表征

在K2CO3-镧系元素氧化物(Sm2O3)-TiO2三元体系中,用固相反应法合成了K2Sm2Ti3O10,利用X射线粉晶衍射仪对K2Sm2Ti3O10进行扫描测定,获得X射线衍射数据,并进行指标化.XRD分析结果表明,K2Sm2Ti3O10为四方晶系,空间群(S.G.)I4/mmm,晶胞参数:a=0.384 28 nm;c=2.971 8 nm;V=0.438 85 nm3;D0=5.165 6 g·mL-1;晶胞分子数Z=2.     

陶瓷贴花及纺织印花的主要成膜物质中聚甲基丙烯酸酯类的组成分析

所分析的样品是从陶瓷贴花及纺织印花的主要成膜物质经溶剂分离后得到的主要成分,用红外光谱分析,确定酯类的组成,用化学降解方法和居里点裂解色谱法验证,其结果为甲基丙烯酸丁酯与甲基丙烯酸甲酯的共聚物,其中甲基丙烯酸丁酯与甲基丙烯酸甲酯的比例为72.4:27.6。该方法具有在剖析实践中应用的价值。     

FAAS测定锂离子电池正极材料LiMn2O4中的杂质钠

采用火焰原子吸收光谱法测定锂离予电池正极材料LiMn2O4中杂质Na的含量.综合考虑了消电离剂氯化铯、盐酸浓度、基体对测Na产生的影响,通过控制酸的浓度和在标准溶液中加入定量基体和消电离剂氯化铯来消除测定误差.由实验结果可知本方法简便易行,灵敏度和准确度高,精密度好,回收率在96.2%-103.8%之间,相对标准偏差(RSD)小于2%(n=10),能够满足锂离子电池正极材料分析的要求.     

Dynamical Transition of Myoglobin and Cu／Zn Superoxide Dismutase Revealed by Molecular Dynamics Simulation

We have carried out parallel moecular dynamics simulations of solvated and non-solvated myoglobin and solvated Cu/Zn superoxide dismutase at different temperatures.By analysis of several methods,the simulati8ons reproduce the quasielastic neutron scattering experimental reults.Below 200K these two proteins behave as harmonic solids with essentially only vibrational motion,while above this temperature,there is a striking dynamic transition into anharmonic motion.Moreover,the simulations further show that water molecules play an important role for this dynamical transition.There is no such sharp dynamical transition in non-solvated proteins and the higher the solvate density is ,the steeper at transition point the curve of mean square displacement versus temperature will be.The simulations also display that the dynamical transition is a general propoerty for globular protein and this transition temperature is a demarcation of enzyme activity.     

超细层状材料A2La2Ti3O10(A=Na,K) 的低温合成及表征

Ultrafine A₂La₂Ti₃O₁₀ (A=K, Na) powders with laminar structure were successfully synthesized by citric acid sol-gel method using ANO₃(A=K, Na)、La(NO₃)₃、Ti(OBu)₄ and citric acid as starting precursors. The crystalline phase of A₂La₂Ti₃O₁₀ can be obtained by thermal decomposition of citrate complex precursors at a relatively low temperature of 800 ℃ (600 ℃ for A=Na), about 300 ℃(500 ℃ for A=Na) lower than that of conventional solid state reaction process. The properties of the citrate precursors and the calcined powders were characterized by Infrared spectroscopy (IR), X-ray diffraction (XRD), transmission electron microscopy (TEM), thermal-gravimetric-differential thermal analysis (TG-DTA), inductively coupled plasma (ICP) and Brunauer-Emmett-Teller (BET) techniques. Results show that the average size of A₂La₂Ti₃O₁₀ powders obtained by citric acid sol-gel route was reduced to 200 nm×250 nm and the specific surface area was up to 19 m²·g^-1. At the same time, the product was with more regular morphological characteristics. The synthesis process and the formation of A₂La₂Ti₃O₁₀ were also discussed. The obtained A₂La₂Ti₃O₁₀ was found to be transformed from A₂La₂Ti₃O_9.5 during the formation process.