平面应变断裂韧度测试的有效性研究

针对平面应变断裂韧度测试厚度存在的问题,研究了几种材料测断裂韧度所需的实际厚度,拟合了平面应力到平面应变过渡状态下σz应力的分布,分析了过渡状态下的裂端应力场.通过分析不同材料特性和应力状态对断裂韧度KIC的影响,结合金属材料断裂的细观机理,认为平面应变断裂韧度KIC反映的是材料正断的性能,仅代表材料发生正断的指标.结果表明:对于某些高韧性材料,即使满足平面应变条件厚度要求,断裂以剪断为主,很难测出KIC;而对于偏脆性材料,即使不满足厚度要求,只要发生正断,也可测出KIC.结合已有试验结果,为平面应变断裂韧度KIC测定的厚度选择,提出一种合理的预测方法.借助三片模型的研究,给出平面应变断裂韧度的正断指标.     

五嗪含氮取代基衍生物结构和性质的理论研究

采用密度泛函理论(DFT)方法在B3LYP/aug-cc-pvDZ理论水平上研究了CN, NO₂, NH₂, N₃, N₂H, NHNH₂, N₄H和N₄H₃等含氮取代基取代五嗪环上的氢原子生成的衍生物, 预测了它们的分子构型、分解能及含能性质. 对衍生物分解能的研究结果表明, CN和NH₂取代的衍生物的分解能比未取代时更高, 而其余基团的取代使分解能降低; 取代基化合物的生成热越大, 取代五嗪中的氢原子后生成衍生物的生成热也越大. N₄H₃, NO₂, H, N₂H, N₄H, N₃和CN取代的五嗪衍生物的单位原子生成热为72.6～108.9 kJ, 比文献报道的三叠氮基-均三嗪的(70.2 kJ)更高. 对于CN, N₂H, N₄H₃, N₃和N₄H取代的衍生物, 其生成热为871.4～1159.3 kJ•mol^－1, 但N₄H和N₄H₃的分解能较小, 稳定性较差. 因此, N₃, N₂H和CN取代的衍生物可能成为高能量、低感度的含能材料.     

Sudden Change of Quantum Discord in Qutrit-Qutrit System Under Depolarising Noise

The effects of decoherence on quantum discord of two-qutrit system under the influence of multilocal, collective and global depolarising noises are investigated. Sudden change of quantum discord with the decoherence parameter and the initial state parameter occurs for the qutrits being coupled to multilocal or global depolarising noises. On the other hand, decoherence cannot induce sudden change of quantum discord when the system is collectively coupled to the depolarising noise. In addition, the local unitary transformation can alter the region in which the phenomenon of sudden change exists.     

Rapid Identification for the Pterocarpus Bracelet by Three-Step Infrared Spectrum Method

In order to explore a rapid identification method for the anti-counterfeit of commercial high value collections, a three-step infrared spectrum method was used for the pterocarpus collection identification to confirm whether a commercial pterocarpus bracelet (PB) was made from the precious species of Pterocarpus santalinus (P. santalinus). In the first step, undertaken by Fourier transform infrared spectroscopy (FTIR) spectrum, the absorption peaks intensity of PB was slightly higher than that of P. santalinus only at 1594 cm⁻¹, 1205 cm⁻¹, 1155 cm⁻¹ and 836 cm⁻¹. In the next step of second derivative IR spectra (SDIR), the FTIR features of the tested samples were further amplified, and the peaks at 1600 cm⁻¹, 1171 cm⁻¹ and 1152 cm⁻¹ become clearly defined in PB. Finally, by means of two-dimensional correlation infrared (2DIR) spectrum, it revealed that the response of holocellulose to thermal perturbation was stronger in P. santalinus than that in PB mainly at 977 cm⁻¹, 1008 cm⁻¹, 1100 cm⁻¹, 1057 cm⁻¹, 1190 cm⁻¹ and 1214 cm⁻¹, while the aromatic functional groups of PB were much more sensitive to the thermal perturbation than those of P. santalinus mainly at 1456 cm⁻¹, 1467 cm⁻¹, 1518 cm⁻¹, 1558 cm⁻¹, 1576 cm⁻¹ and 1605 cm⁻¹. In addition, fluorescence microscopy was used to verify the effectiveness of the above method for wood identification and the results showed good consistency. This study demonstrated that the three-step IR method could provide a rapid and effective way for the anti-counterfeit of pterocarpus collections.     

使用四乙基氢氧化铵作为有机模板剂和常规硅铝源直接合成SSZ-13沸石分子筛

使用四乙基氢氧化铵作为有机模板剂,利用常规铝源和硅源而不需要高硅Y沸石作为起始原料,同时加入适量的沸石晶种直接合成了SSZ-13沸石分子筛.所合成的沸石产物结晶度好,具有良好的水热稳定性,并在氨选择性催化还原(NH₃-SCR)反应中显示出优异的催化性能,为其在工业上广泛应用提供了可能.     

Bayesian Variable Selection and Estimation in Semiparametric Simplex Mixed-Effects Models with Longitudinal Proportional Data

In the development of simplex mixed-effects models, random effects in these mixed-effects models are generally distributed in normal distribution. The normality assumption may be violated in an analysis of skewed and multimodal longitudinal data. In this paper, we adopt the centered Dirichlet process mixture model (CDPMM) to specify the random effects in the simplex mixed-effects models. Combining the block Gibbs sampler and the Metropolis–Hastings algorithm, we extend a Bayesian Lasso (BLasso) to simultaneously estimate unknown parameters of interest and select important covariates with nonzero effects in semiparametric simplex mixed-effects models. Several simulation studies and a real example are employed to illustrate the proposed methodologies.     

Separation and Purification of Two Saponins from Paris polyphylla var. yunnanensis by a Macroporous Resin

An effective method for separating and purifying critical saponins (polyphyllin II and polyphyllin VII) from a Paris polyphylla var. yunnanensis extract was developed in this study which was environmentally friendly and economical. Static adsorption kinetics, thermodynamics, and the dynamic adsorption-desorption of macroporous resins were investigated, and then the conditions of purification and separation were optimized by fitting with an adsorption thermodynamics equation and a kinetic equation. Effective NKA-9 resin from seven macroporous resins was screened out to separate and purify the two saponins. The static adsorption and dynamic adsorption were chemical and physical adsorption dual-processes on the NKA-9 resin. Under the optimum parameters, the contents of polyphyllin II and polyphyllin VII in the product were 17.3-fold and 28.6-fold those in plant extracts, respectively. The total yields of the two saponins were 93.16%. This research thus provides a theoretical foundation for the large-scale industrial production of the natural drugs polyphyllin II and polyphyllin VII.     

1，1－二氯双硅烷热分解的理论研究

用ＭＮＤＯ方法研究了１，１－二氯双硅烷的热分解反应，得到了两条反应途径及其过渡态，证明了１，１－二氯双硅烷的热分解是通过１，２－氢迁移和２，１－氢迁移实现的。     

Explicit representations of minimal immersions of 2-spheres intoS 2m

For all minimal immersions of the 2-sphereS ² into the unit 2m-sphereS ^2m with area 2π[m(m+1)+2], we are able to give an explicit representation by some real parameters. This representation is rather important in the study of minimal 2-spheres inS ^2m because the parameters concerned are independent of each other. Particular examples are given and a classification theorem is also obtained. Supported by NNSF of China and NSF of Henan     

CO和H2与Ni基催化剂的相互作用研究

用活性测试和程序升温动态红外光谱方法研究了ＣＯ和Ｈ２在Ｎｉ／Ａｌ２Ｏ３催化剂上的行为，并用量子化学从头算方法进行了模拟表征。结果表明，在较低温度下，ＣＯ在Ｎｉ／Ａｌ２Ｏ３上的线式吸附态和桥式吸附态相比，桥式对ＣＯ压力更敏感，而线式则对温度更敏感。