BTATz-Pb复合物对双基和RDX-改性双基推进剂的热行为、非等温动力学及燃烧性能的影响

制备了含3,6-双(1-氢-1,2,3,4-四唑-5-氨基)-1,2,4,5-四嗪(BTATz)铅复合物(LCBTATZ)的双基推进剂和改性双基推进剂. 采用热重-微商热重法(TG-DTG)及差示扫描量热法(DSC)研究了其热分解行为和非等温分解动力学并在此基础上评价了其热安全性. 结果表明, LCBTATz-DB复合物中在350-540 K之间只存在一个放热分解峰, LCBTATz-CMDB复合物中存在两个连续的放热分解峰在390-540 K温度范围内, 其机理方程分别为: f(α)=α^-1/2和f(α)=2(1-α)^3/2. 计算了热加速分解温度(T_SADT)、热爆炸临界温度(T_b)、热点火温度(T_TIT)和绝热至爆时间(t_Tlad),其值分别为: DB001复合物T_SADT=444.50 K, T_TITT=453.96 K, T_b=471.84 K; t_Tlad=39.36 s; CMDB100复合物, T_SADT=442.38 K, T_TITT=452.89 K,T_b=464.13 K,t_Tlad=21.3 s,并以此来评价化合物的热安全性. 考察了LCBTATz-DB以及LCBTATz-CMDB的燃烧性能, 结果表明LCBTATZ 是一种高效的双基燃烧催化剂, 在较大的压力范围内可以显著的提高燃速并且大幅度的降低压力指数. 对于双基推进剂在2-8 MPa压力范围内出现了明显的超燃速现象, 8-12 MPa出现了“麦撒”效应, 对于改性双基推进剂的压力指数降到0.18.     

Large magnetic entropy change near room temperature in the LaFe11.5Si1.5H1.3 interstitial compound

The LaFe_11.5Si_1.5H_1.3 interstitial compound has been prepared. Its Curie temperature T_C (288 K) has been adjusted to around room temperature, and the maximal magnetic entropy change (|ΔS|～17.0 J·kg^-1·K^-1 at T_C) is larger than that of Gd (|ΔS|～9.8 J·kg^-1·K^-1 at T_C=293 K) by ～73.5% under a magnetic change from 0 to 5 T. The origin of the large magnetic entropy change is attributed to the first-order field-induced itinerant-electron metamagnetic transition. Moreover, the magnetic hysteresis of LaFe_11.5Si_1.5H_1.3 under the increase and decrease of the field is very small, which is favourable to magnetic refrigeration application. The present study suggests that the LaFe_11.5Si_1.5H_1.3 compound is a promising candidate as a room-temperature magnetic refrigerant.     

LaFe11.2Co0.7Si1.1合金在室温区的巨大磁熵变

在具有立方NaZn13型结构的稀土铁基化合物LaFe11.2Co0.7Si1.1中发现室温的巨大磁熵变，磁熵变的峰值位于居里温度Tc=274K处，5T外磁场下达到－20.3J/kg K约为相同的温区下金属Gd的2倍，LaFe11.2Co0.7Si1.1合金中强烈的磁弹性耦合，导致晶格在居里温度处出现巨大负膨胀，这是其巨大磁熵变的来源。     

Synthesis and Crystal Structure of a Copper(II) Compound Constructed by N-(4,6- Dimethoxylpyrimidin)-N'-(ethoxycarbonyl)thiourea

A copper(Ⅱ) complex Cu(L)2(NO3)2 constructed by the L (L = N-(4,6-dime- thoxylpyrimidin)-N'-(ethoxycarbonyl)thiourea) ligand crystallizes in monoclinic, space group C2/c with a = 16.2416(16), b = 9.1385(7), c = 22.0008(18) (A),β = 108.077(2)°, V ＝ 3104.3(5)(A)3, Dc = 1.627 g/cm3, Z = 4, C20H28CuN10O14S2, Mr = 760.18, μ(MoKα) = 0.920 mm-1, F(000) = 1564, R = 0.0471 and wR = 0.1284 for 2239 observed reflections (I > 2σ(I)). X-ray diffraction shows the existence of weak complementary intramolecular N-H…O (DA) hydrogen bonds which further strengthen the coordination from the two L ligands with the Cu(II) ion, intermolecular C-H…O hydrogen bonds and weak π…π stacking interactions, leading to the formation of a multi-dimen- sional supramolecular network.     

Area and Entropy Spectrum of Gauss-Bonnet Gravity in de Sitter Space-Times for Black Hole Event Horizon

In this paper, we use the modified Hod's treatment and the Kunstatter's method to study the horizon area spectrum and entropy spectrum in Gauss-Bonnet de-Sitter space-time, which is regarded as the natural generalization of Einstein gravity by including higher derivative correction terms to the original Einstein-Hilbert action. The horizon areas have some properties that are very different from the vacuum solutions obtained from the frame of Einstein gravity. With the new physical interpretation of quasinormal modes, the area/entropy spectrum for the event horizon for nearextremal Gauss-Bonnet de Sitter black holes are obtained. Meanwhile, we also extend the discussion of area/entropy quantization to the non-extremal black holes solutions.     

Magnetocaloric properties of the La0.7Pr0.3Fe13−xSix compounds

Magnetic entropy change ΔS_m, hysteresis loss and refrigerant capacity of NaZn₁₃-type La_0.7Pr_0.3Fe_13−xSi_x (1.5?x?2.0) compounds have been investigated. The Curie temperature T_C increases linearly with the increase of silicon concentration. Although the maximum value of ΔS_m under a field change of 0−5 T decreases from 30.5 to 11.4 J/kg K as x increases from 1.5 to 2.0, the hysteresis loss at T_C reduces remarkably from 89.2 J/kg for x=1.5 to zero for x=2.0 because the increase of Si content can weaken the itinerant electron metamagnetic transition. The effective refrigerant capacity RC_eff is maintained at high values of 362−439 J/kg for a field change of 0−5 T. This implies that a large ΔS_m and a high RC_eff can be achieved simultaneously in the La_0.7Pr_0.3Fe_13−xSi_x compounds.     

Knotted Solitons in an Interacting Mixture of a Charged and a Neutral Superfluid for Neutron Stars

By making use of the decomposition of U（1） gauge potential theory and the C-mapping method we discuss a mixture of interacting neutral and charged Bose condensates, which is supposed being realized in the interior of neutron stars in the form of a coexistent neutron superfluid and protonic superconductor. We propose that this system possesses vortex lines and two classes of knotted solitons. The topological charge of the vortex lines are characterized by the Hopf indices and the Brower degrees of φ-mapping, and the knotted solitons are described by nontrivial Hopf invariant and the BF action respectively.     

葡萄酒中7种酚酸的色谱电化学分析

建立了同时测定葡萄酒中没食子酸、原儿茶酸、丁香酸、p-香豆酸、咖啡酸、绿原酸和阿魏酸等7种生物活性酚酸的反相高效液相色谱电化学分析新方法,并测定了5种国产不同品牌的葡萄酒.采用HypersilODS色谱柱(250mm×4.0mm,5.0μm),流动相为甲醇-4%醋酸,梯度洗脱,流速为0.8mL/min,工作电压为0.7V,柱温为30℃.实验结果表明,电化学法的检出限比紫外法的检出限低4～600倍.     

TDNAZ·HNO3和DNAZ·HCl的结构及性能

钝感高能炸药1,3,3-三硝基氮杂环丁烷(TNAZ)可由3,3-二硝基氮杂环丁烷(DNAZ)进行合成. 在合成DNAZ的过程中, 得到了中间产物N-叔丁基-3,3-二硝基氮杂环丁烷硝酸盐(TDNAZ·HNO3)和3,3-二硝基氮杂环丁烷盐酸盐(DNAZ·HCl). 培养了二者的单晶, 并通过X射线单晶结构分析法测定了它们的晶体结构. TDNAZ·HNO3属于正交晶系, Pnma空间群, 晶胞参数a=1.2697(3) nm, b=0.8179(2) nm, c=1.1621(3) nm, V=1.2067 nm3, Z=4. DNAZ·HCl属于正交晶系, Cmc21空间群, 晶胞参数a=0.6681(2) nm, b=1.0441(2) nm, c=0.9971(2) nm, V=0.6955 nm3, Z=4. 用密度泛函理论方法对该二种化合物进行了几何优化和频率计算, 获得分子结构、原子上Hirshfeld电荷、原子间Mayer键级和前沿轨道能量及组成. 基于分子和电子结构信息从理论上解释了相关反应机理, 并对两种化合物的热稳定性进行了比较.