LongikaurinB的晶体结构分析

长管香茶菜B（LongikaurinB）分子的化学计量式为C22H30O7，Mr=406．47，用X射线衍射法确定其晶体结构，该结晶是无色透明柱状，属单斜晶系，空间和群为P21，晶胞参数：a=11．893（2），b=6.380（2），c=13．205（2）A，β=99．39（2）°，Z=2，V=988．5（4）A3，Dc＝1．366g／cm3，F（000）＝436，u＝0．9cm-1。应用直接法解析分子结构，以最小二乘法修正结构参数。最终可靠因子R=0.042，Ra=0.043。结果表明，该化合物为长管香茶菜B，属7，20-氧桥-对映-贝壳杉烯型工花化合物。结构与功能关系研究表明LongikaurinB化合物可能具有抗肿瘤生物活性。     

碳微线圈的气-液-固-固生长机理

碳微线圈具有类似DNA的双螺旋结构, 通常以镍为催化剂, 噻吩为助剂采用CVD法制备, 但是对于它的生长机理人们仍不十分清楚. 本文发现构成碳微线圈的碳纤维由三条亚纤维组成, 提出了碳微线圈的气-液-固-固生长机理, 并以此对实验事实做出合理解释.     

Vibration Characteristics of Acoustically Levitated Object with Rigid and Elastic Reflectors

Levitation stability is a crucial factor that influences acoustic levitation capability. We present two sample-including models for a single-axis acoustic levitator with either a rigid or elastic reflector. Numerical analysis shows that, with the rigid reflector, both the decay time from initial disturbance and the vibration amplitude increase with sample density, which is unfavorable for levitation stability. However, with the elastic reflector, the decay time and the vibration amplitude are greatly reduced by choosing appropriate parameters of the reflector. Experimental results agree well with theoretical predictions, indicating that levitation stability can be remarkably enhanced by replacing the rigid reflector with an elastic reflector.     

Reactivity of tetracyanoquinodimethane with cobalt(II) chloride and bis(diphylphospino)methane in air

The reactions of CoCl₂·6H₂O, dppm (bis(diphenylphosphino)methane) and TCNQ (7,7,8,8-tetracyanoquinodimethane), with different ratios of the components, provided three new compounds, [Co(dppmdo)₃][TCNQ]₂1 (dppmdo = P,P′-dioxo-bis(diphenylphosphinyl)methane), [Co(dppmdo)₃][(μ-TCNQ)-CoCl₃] 2, and [Co(dppmdo)₃][(μ-DCBE)-CoCl₃] 3 (DCBE = p-dicyanomethyl-benzoic ethyl ester). These products were characterized by IR, UV–Vis and UV–Vis-NIR spectra, X-ray crystallography, magnetic susceptibility measurements and cyclic voltammograms. 1 and 2 reveal low-energy transitions in the near-infrared region, which can be attributed to intra-ligand transitions involving radical anions (TCNQ/TCNQ⁻). It is interesting to note that, except for the redox potentials which are anodically shifted, indicating that it is easier to reduce TCNQ in 1 and 2 than the free TCNQ molecule, the electrochemistry of compounds 1 and 2 resemble that of the independent organic acceptor TCNQ. The magnetic properties suggest that an amount of electron transfer has occurred from the Co^II complex, [Co(dppmdo)₃]²⁺, to the TCNQ⁻ anions in 1; an amount of electron transfer also has occurred from the Co^II cation to the TCNQ⁻ anion via a cyanide-bridge in 2; there is a mixture of spin transition of Co^II ions and antiferromagnetic coupling between Co^II ions in 3.     

羧酸气体热容的测定与研究

The vapor heat capacities of acetic acid, propionic acid, n-butyric acid at various temperatures under atmospheric pressure were measured with a multicomponent vapor flow calorimeter. The results show that the vapor heat capacities of carboxylic acids are much larger than those of the ideal gases at the same temperature and that the vapor heat capacities decrease with increasing temperature. The effect of association in the vapor phase on the vapor heat capacity was studied.     

[（PbCl2）0.55（PbO）0.45]1—x（KCl）x系离子导电性研究

对POGI_2-PbO体系进行KGl掺杂改性研究.实验表明少量KGl掺杂试样可直接在空气中烧结制备.对[(PbCl_2)_(0.55)(PbO)_(0.45)]_(1-x)(KCl)_x(x=0～0.30)的试样进行了电学测试.并做了X射线物相鉴定以确定高电导体系的主相.对0.05≤x≤0.22之间的体系电导率低谷现象进行了解释.     

铝掺杂针铁矿的制备、表征及吸附氟的特性

水热条件下制备了针铁矿(Goe)和几种铝掺杂针铁矿(Goe-Al_(0.1),Goe-Al_(0.2)和Goe-Al_(0.4)),用X射线衍射(XRD)、扫描电镜(SEM)、氮气物理性吸附、酸碱滴定等手段对样品进行了表征,并研究了它们对氟离子的吸附特性。结果表明,随着铝掺杂量的增加,铝掺杂针铁矿的结晶度不断减弱、颗粒的长度不断减小。4种样品的微孔表面积、孔体积和表面分形度都表现为GoeGoeAl0.1Goe-Al_(0.2)Goe-Al_(0.4),而孔径分布表现为相反的顺序。Goe、Goe-Al_(0.1)、Goe-Al_(0.2)和Goe-Al_(0.4)的电荷零点(PZC)分别为8.2、8.3、8.5和8.7,pH=5.0时它们的表面电荷量分别为0.66、0.83、1.03和1.19 mmol·g~(-1)。准二级动力学模型适合描述4种样品对氟的吸附动力学过程,表明化学吸附是主要作用机制。一位Langmuir模型可较好的拟合等温吸附数据(R2为0.967~0.981),二位Langmuir模型对等温吸附数据的拟合度更高(R2为0.982~0.995),而Freundlich模型的拟合度较低(R2为0.877~0.912)。初始pH=5.0时,Goe、Goe-Al_(0.1)、Goe-Al_(0.2)和Goe-Al_(0.4)对氟的最大吸附容量分别为8.83、10.24、11.72和12.86 mg·g~(-1)。可见,铝掺杂针铁矿对土-水环境中氟的吸附容量高于纯针铁矿。     

Engineering hollow covalent organic framework particle through self-templated crystallization

Nano/microparticles with hollow structures have many applications in various fields. However, engineering hollow covalent organic framework (COF) particles in a simple and efficient manner remains a significant challenge. In this study, we propose a self-template crystallization method to prepare imine-based COF microparticles with tailored shell thickness and high crystallinity. This method involves the post-transformation of amorphous microparticles in a highly reversible reaction system containing monofunctional competitors. The amorphous precursors with high-Gibbs free energy decompose and reconstruct to form highly crystalline COFs in situ on the particle surface. This process allows for the preparation of various Schiff-base COF particles with good crystallinity and tailored hollow structures, with diameters ranging from 120 to 680 nm and shell thicknesses of 27–96 nm. These COF particles have well-defined micropore sizes centered between 1.0 and 4.0 nm and a high-specific surface area of up to 543 m² g⁻¹. The resulted COF particles could be used to support ethylene oligomerization catalysts for improving their activity and selectivity, that is, the mass fraction of α-olefins above C₁₀ increased from almost zero to 52.7% after COF supporting. Our method thus provides an efficient way to precisely tailor the microstructure and morphology of COF materials for advanced applications.     

Bright soliton interactions in a $$\mathbf (2 +\mathbf 1) $$ ( 2 + 1 ) -dimensional fourth-order variable-coefficient nonlinear Schrödinger equation for the Heisenberg ferromagnetic spin chain

Nonlinear Dynamics - Interactions of bright solitons in the Heisenberg ferromagnetic spin chain, governed by a $$(2+1)$$ -dimensional nonlinear Schrödinger equation with variable coefficients,...     

Variat ional-Cumulant Expansion on the Five-State Clock Model

The phase transition of the 5-state dock model has been studied by standard variationalcumulant expansion (VCE) method. We calculated the fiee energy (F) and the internal energy (E) to the fourth order approximation and the specific heat (C) to the third order approximation with the trial action of one variational parameter. The position of the phase transition point given above is in agreement with the results of the Monte Carlo (MC). We also calculated the model to the third order approximation with the trial action of two variational parameters. The comparison of the results for one variational parameter with that for two is given. From this, we can see how the choice of the trial action affects the result and the trial action must be equivalent to the action of the system. All above has shown that the VCE is convergent in the calculation of the 5-state clock model.