Density functional theoretical study of A series of pentazolide compounds \hbox{A}_{\it n}(\hbox{N}_5)_{\rm 6-{\it n}}^{\it q} (A = B, Al, Si, P, and S; n = 1–3; q = +1, 0, −1, −2, and −3)

The structure and the stability of pentazolide compounds $\hbox{A}_{\it n}(\hbox{N}_5)_{\rm 6-{\it n}}^{\it q}$ (A = B, Al, Si, P, and S; n= 1–3; q = +1, 0, ?1, ?2, and ?3), as high energy-density materials (HEDMs), have been investigated at the B3LYP/6-311+G* level of theory. The natural bond orbital analysis shows that the charge transfer plays an important role when the $\hbox{A}_{\it n}(\hbox{N}_5)_{\rm 6-{\it n}}^{\it q}$ species are decomposed to $\hbox{A}_{\it n}(\hbox{N}_5)_{\rm 5-{\it n}}\hbox{N}_3^{\it q}$ and N₂. The more negative charges are transferred from the N₂ molecule after breaking the N₅ ring, the more stable the systems are with respect to the decomposition. Moreover, the conclusion can be drawn that ${\hbox{Al}(\hbox{N}_5)_5^{2-}}$ and ${\hbox{Al}_2(\hbox{N}_5)_4^{2-}}$ are predicted to be suitable as potential HEDMs.     

A ratiometric near-infrared naphthalimide-based fluorescent probe with high sensitivity for detecting Fe2+ in vivo

Iron is one of the essential trace elements in the human body. It plays an important role in human biology and pathology. Deregulation of iron levels in cells is associated with disease development. In this work, we synthesized a novel near-infrared intramolecular charge transfer (ICT) based ratiometric fluorescent probe to detect Fe²⁺, by using naphthalimide and indole moieties as building blocks. Our work showed that the radiometric probe has excellent selectivity, sensitivity and rapid response. Moreover, we could successfully perform real-time monitoring of Fe²⁺ in HeLa cells and C. elegans.     

随机梯度下降法的一些性质(英文)

本文研究了一般核空间下的随机梯度下降法.通过迭代方法,给出了该算法的一些重要性质,这些性质对于研究收敛速度起到至关重要的作用.     

原子吸收光谱法测定女贞属苦丁茶中金属含量

用火焰原子吸收光谱法测定贵州不同产地的女贞属苦丁茶中Cu、Zn、Ca,Mg 4种金属的含量,并比较含量差异.测定结果表明,女贞属苦丁茶中4种金属元素的含量较高,Cu元素含量为11.28-18.15μg·g-1、Zn元素含量为25.92-43.21μg·g-1、Ca元素含量为2371-12091μg·g-1、Mg元素含量...     

The wake potential in the viscous quark–gluon plasma

Based on the dielectric function derived from the viscous chromohydrodynamic approach, we investigate the wake potential induced by a fast parton traveling through the viscous quark–gluon plasma. An oscillatory wake potential and a Lennard-Jones potential are found in the backward direction for the fast parton speeds v=0.99c$v=0.99c$ and v=0.55c$v=0.55c$, respectively. In the forward direction, there is a modified Coulomb screening potential for both two speeds. When v=0.99c$v=0.99c$, shear viscosity makes the oscillation of potential more remarkable with the increase of η/s$\eta /s$. While v=0.55c$v=0.55c$, the viscous effects on the wake potential are very trivial in both the forward and backward directions. Finally, we give some explanations for the speed-dependent viscous effects on the wake properties.     

Qualitative analysis and traveling wave solutions for the perturbed nonlinear Schrödinger's equation with Kerr law nonlinearity

In this Letter, we investigate the perturbed nonlinear Schrödinger's equation (NLSE) with Kerr law nonlinearity. All explicit expressions of the bounded traveling wave solutions for the equation are obtained by using the bifurcation method and qualitative theory of dynamical systems. These solutions contain bell-shaped solitary wave solutions, kink-shaped solitary wave solutions and Jacobi elliptic function periodic solutions. Moreover, we point out the region which these periodic wave solutions lie in. We present the relation between the bounded traveling wave solution and the energy level h. We find that these periodic wave solutions tend to the corresponding solitary wave solutions as h increases or decreases. Finally, for some special selections of the energy level h, it is shown that the exact periodic solutions evolute into solitary wave solution.     

Three New Sesquiterpene Pyridine Alkaloids from Euonymus fortunei

Three new macrocyclic β‐dihydroagarofuran‐type sesquiterpene pyridine alkaloids, fortuneines A ( 1 ), B ( 2 ), and C ( 3 ), together with the four known alkaloids wilfornine E ( 4 ), aquifoliunine E‐I ( 5 ), euoverrine B ( 6 ), and euojaponine I ( 7 ), were isolated from the aerial parts of Euonymus fortunei. Their structures were elucidated by spectroscopic methods, including HR‐ESI‐MS, ¹H‐ and ¹³C‐NMR, DEPT, ¹H,¹H‐COSY, HSQC, HMBC, and ROESY. This is the first isolation of the above sesquiterpene pyridine alkaloids from this plant, except for compound 6 .     

Synthesis of dimethyl adipate from cyclopentanone and dimethyl carbonate over solid base catalysts

A facile route for the synthesis of dimethyl adipate (DAP) from cyclopentanone and dimethyl carbonate (DMC) in the presence of solid base catalysts has been developed.It was found that the intermediate carbomethoxycyclopentanone (CMCP) was produced from cyclopentanone with DMC in the first step,and then CMCP was further converted to DAP by reacting with a methoxide group.The role of the basic catalysts can be mainly ascribed to the activation of cyclopentanone via the abstraction of a proton in the α-position by base sites,and solid bases with moderate strength,such as MgO,favor the formation of DAP.     

Morgenstern族次序统计量的协变量的分布

本文研究了Morgenstern族次序统计量的协变量的分布及其在筛选测验中的应用.利用排序集抽样的方法,获得了分组测验情形下每组协变量的极值的分布.最后,将上述结果应用至总体为Gumbel二维指数分布和二维均匀分布的情形,给出了不同的样本量下选择问题的筛选效率.     

Influence of Non-uniform Temperature Field on Spectra of Fibre Bragg Grating

We simulate the spectrum characteristics of fibre Bragg grating （FBG） with non-uniform temperature using the transmission matrix method, and the results are analysed. It is found that firstly the modulated coefficient of average refractive index is a very important parameter that influences the spectrum characteristic of the fibre Bragg grating, and secondly the spectrum curves are different in different temperature fields at the same parameter. Hence, we can determine the metrical temperature by analysing the spectrum of fibre Bragg grating.