四元轻稀土硝酸盐水溶液体系{H2O+La(NO3)3+Pr(NO3)3+Nd(NO3)3}的热力学研究

在298.15 K条件下, 利用等压法研究了四元轻稀土硝酸盐水溶液{H2O La(NO3)3 Pr(NO3)3 Nd(NO3)3}及其3个二元亚系{H2O La(NO3)3}, {H2O Pr(NO3)3}和{H2O Nd(NO3)3}的热力学性质. 以NaCl或CaCl2水溶液为参考溶液, 测定了不同水活度条件下该四元溶液的渗透系数及各溶质组元的活度系数. 实验结果表明, 上述四元系与其3个二元亚系之间存在简单共性, 在实验误差允许范围之内(|Δ|≤0.0010), 该四元系符合偏理想溶液模型.     

Partial Oxidation of Methane to Synthesis Gas over Hexaaluminates LaMAl11O19-δ catalysts

A series of M-substituted hexaaluminates LaMAl11O19-δ (M=Fe, Co, Ni, Mn, and Cu)were prepared and characterized by XRD, XPS, TPR and TGA techniques, respectively. They exhibited different reducibility and catalytic activity for partial oxidation of methane (POM) to synthesis gas. Among the LaMAl11O19-δ samples, LaNiAl11O19-δ showed the best catalytic activity for the topic reaction and selectivity for synthesis gas at 780 ℃ for 2 h. The conversion of CH4 was over 99.2%, and the product selectivity for both CO and H2 was above 90.3%.     

氧载体的氧物种直接氧化甲烷制合成气

甲烷部分氧化制合成气由于合成气中n(H2)/n(CO)接近2,可直接用于甲醇合成或烃类F-T合成等后续工业过程而在国内外受到了广泛的关注。利用氧载体的氧物种在无气相氧下直接选择氧化甲烷制合成气是天然气化工利用的新方法,本文介绍了该方法的基本原理、概念工艺和对氧载体的性能要求,对应用于该方法的铈基复合氧化物的掺杂和助剂对选择氧化甲烷性能的影响、钙钛矿氧化物氧载体的氧缺陷、氧物种迁移、结构稳定性及其氧物种氧化甲烷的性能进行了阐述和分析,提出了控制氧载体表面状态是获得高合成气选择性的关键,并对该技术今后的研究重点进行了展望。     

近红外光谱快速测定红花逆流提取过程中羟基红花黄色素A的含量

采用近红外光谱(NIRS)透射法对红花罐组式逆流提取过程中羟基红花黄色素A(Hydroxysafflor yellow A,HSYA)的含量进行快速无损的测定.在红花逆流提取过程中,以高效液相色谱法(HPLC)为对照分析方法,测定提取液中羟基红花黄色素A的含量,运用偏最小二乘(PLS)法建立NIR光谱与羟基红花黄色素A的HPLC分析值之间多元校正模型,并对逆流提取过程的未知样本进行含量预测.校正模型相关系数达到0.982,预测相关系数达到0.965,RMSEC和RMSEP分别为0.053和0.075,RSEC和RSEP分别为3.96%和5.25%.结果表明,NIRS可以作为一种准确、快速、无损的检测方法用于检测中药逆流提取过程有效成分含量变化规律.     

Short-wave near-infrared spectroscopy analysis of major compounds in milk powder and wavelength assignment

In this study, short-wave near-infrared (NIR) spectroscopy at 800–1050 nm region was investigated for the analysis of main compounds in milk powder. Through quantitative analysis, the feasibility is further demonstrated for the simultaneous measurement of fat, proteins and carbohydrate in milk powder. Two models, partial least-squares and least-squares support vector machine, were compared and utilized for regression coefficients and loading weights. The affect of standard normal variate spectral pretreatment to model performance was evaluated. Based on the resulted coefficients and loading weights, interesting wavelength regions of nutrition in milk powder are screened and the assignment of all specific wavelengths is firstly proposed in the details associated with chemical base. Instead of the whole short-wave NIR spectral data, these assigned wavelengths which can be reliably exploited were used for the content determination. Compared with other spectroscopy technique, assigned short-wave NIR spectral wavelengths did a good work. Determination coefficients for prediction are 0.981, 0.984, and 0.982, respectively for three components. The proposed wavelength assignment in the short-wave NIR region could be used for the component contents determination of milk powder, and could be as a guidance to interpret the spectra of milk powder.     

VOx/SBA-15催化剂上甲苯气相部分氧化

采用等体积浸渍法制备了不同负载量的VOx/SBA-15催化剂。UV-Vis和H2-TPR等表征结果表明,在较低钒负载量下,钒物种的分散程度较高,主要以孤立的VO4 3－以及少量聚合体V－O－V形式存在;钒负载量较高时会有大量的聚合体V－O－V甚至晶相V2O5出现,而且,催化剂的酸性随着钒物种的高度分散而降低。甲苯气相部分氧化反应结果表明,随着钒负载量的提高,苯甲醛的选择性先升后降,CO、CO2等选择性逐渐提高。这是由于催化剂存在大量的聚合体V－O－V和晶相V2O5时,聚集态钒物种表面较多的酸量促使苯甲醛深度氧化。在相同钒负载量下,催化剂VOx/SBA-15的钒物种分散状态优于VOx/MCM-41和VOx/SiO2,从而使得催化剂VOx/SBA-15呈现较高的苯甲醛选择性。     

近红外光谱法测定5-羟基色氨酸的含量

本文利用近红外光谱法建立了5-羟基色氨酸的偏最小二乘(PLS)定量模型。采用相关数法选择波段以及二阶导数、Norris derivative平滑滤波进行数据预处理,所建校正模型的R为0.99907,RMSEC为0.0638,RMSEP为0.0675。经验证模型的预测性能良好,为5-HTP的快速测定提供了一种方法。     

Characterization of a Stable Adaptive Calibration Model Using Near-Infrared Spectroscopy and Partial Least Squares with a Kalman Filter

The calibration model of near-infrared (NIR) spectra established using the Kalman filter-partial least square (partial least squares combined with a Kalman filter) method can be adapted to outdated equipment, environmental changes, external samples, and other applications. However, the variance of the measurement noise estimation for NIR spectrum measurements cannot be easily obtained using Kalman filter-partial least squares; therefore, the variance in the measurement noise is often assumed to be zero for the Kalman filter-partial least square calibration model, which affects the stability of the model. In this study, the measured input and output data were used effectively, and the gamma test method for estimating the measurement noise variance was used to improve the stability of the Kalman filter-partial least square calibration model. First, an accurate estimation of the measurement noise variance was obtained, and accurate modeling was then performed using Kalman filter-partial least squares. Finally, 600 abandoned drilling fluid samples were used to confirm the validity of the proposed method. The Kalman filter-partial least square and gamma test-Kalman filter-partial least square methods are compared. Testing of external samples 401–600 demonstrated that the stability of the Kalman filter-partial least square model decreased. The root mean square error of the prediction of the Kalman filter-partial least square model was 27.135, which was worse than that of the gamma test-Kalman filter-partial least square model (20.307). The validation results show that the proposed method has better stability in tracking the evolution of the NIR spectrometer’s measurement state.     

A Characterization of Maximally Entangled Two-Qubit States

As already known by Rana’s result, all eigenvalues of any partial-transposed bipartite state fall within the closed interval [−12,1]. In this note, we study a family of bipartite quantum states where the minimal eigenvalues of partial-transposed states are −12. For a two-qubit system, we find that the minimal eigenvalue of its partial-transposed state is −12 if and only if such a two-qubit state is maximally entangled. However this result does not hold in general for a two-qudit system when the dimensions of the underlying space are larger than two.     

一类混合单调算子的不动点定理

运用锥理论与迭代方法,讨论了在较弱条件下一类混合单调算子的不动点的存在唯一性,所得结果是某些已有结果的本质改进和推广.